Some bacteria produce intracellular nutrient storage granules for later use, such as glycogen, polyphosphate, sulfur or polyhydroxyalkanoates. Certain bacterial species, such as the photosynthetic Cyanobacteria, produce internal gas vesicles, which they use to regulate their buoyancy – allowing them to move up or down into water layers with different light intensities and nutrient levels. Intracellular membranes called chromatophores are also found in membranes of phototrophic bacteria. Used primarily for photosynthesis, they contain bacteriochlorophyll pigments and carotenoids. An early idea was that bacteria might contain membrane folds termed mesosomes, but these were later shown to be artifacts produced by the chemicals used to prepare the cells for electron microscopy. Inclusions are considered to be nonliving components of the cell that do not possess metabolic activity and are not bounded by membranes. The most common inclusions are glycogen, lipid droplets, crystals, and pigments. Volutin granules are cytoplasmic inclusions of complexed inorganic polyphosphate. These granules are called metachromatic granules due to their displaying the metachromatic effect; they appear red or blue when stained with the blue dyes methylene blue or toluidine blue. Gas vacuoles, which are freely permeable to gas, are membrane-bound vesicles present in some species of Cyanobacteria. They allow the bacteria to control their buoyancy. Microcompartments are widespread, membrane-bound organelles that are made of a protein shell that surrounds and encloses various enzymes. Carboxysomes are bacterial microcompartments that contain enzymes involved in carbon fixation. Magnetosomes are bacterial microcompartments, present in magnetotactic bacteria, that contain magnetic crystals.

What types of intracellar nutrient can bacteria produce?

glycogen, polyphosphate, sulfur or polyhydroxyalkanoates

How does gas vesicles produced by Cyanobacteria help her to move in water?

move up or down into water layers with different light intensities

What are chromatophores used for?

photosynthesis

What are the most common nonliving compositions in bacteria?

glycogen, lipid droplets, crystals, and pigments

What gas vacuoles are respoonsible for in bacteria?

to control their buoyancy


In most bacteria, a cell wall is present on the outside of the cell membrane. The cell membrane and cell wall comprise the cell envelope. A common bacterial cell wall material is peptidoglycan (called "murein" in older sources), which is made from polysaccharide chains cross-linked by peptides containing D-amino acids. Bacterial cell walls are different from the cell walls of plants and fungi, which are made of cellulose and chitin, respectively. The cell wall of bacteria is also distinct from that of Archaea, which do not contain peptidoglycan. The cell wall is essential to the survival of many bacteria, and the antibiotic penicillin is able to kill bacteria by inhibiting a step in the synthesis of peptidoglycan.

What composes the cell envelope?

cell membrane and cell wall

What is most common cell wall material?

peptidoglycan

Are cell walls of bacteria similar to cell walls of plants and fungi?

Bacterial cell walls are different

What are the main materials of cell walls of plants and fungi?

cellulose and chitin

How can antibiotic penicillin destroy bacteria?

by inhibiting a step in the synthesis of peptidoglycan


Gram-positive bacteria possess a thick cell wall containing many layers of peptidoglycan and teichoic acids. In contrast, gram-negative bacteria have a relatively thin cell wall consisting of a few layers of peptidoglycan surrounded by a second lipid membrane containing lipopolysaccharides and lipoproteins. Lipopolysaccharides, also called endotoxins, are composed of polysaccharides and lipid A that is responsible for much of the toxicity of gram-negative bacteria. Most bacteria have the gram-negative cell wall, and only the Firmicutes and Actinobacteria have the alternative gram-positive arrangement. These two groups were previously known as the low G+C and high G+C Gram-positive bacteria, respectively. These differences in structure can produce differences in antibiotic susceptibility; for instance, vancomycin can kill only gram-positive bacteria and is ineffective against gram-negative pathogens, such as Haemophilus influenzae or Pseudomonas aeruginosa. If the bacterial cell wall is entirely removed, it is called a protoplast, whereas if it is partially removed, it is called a spheroplast. β-Lactam antibiotics, such as penicillin, inhibit the formation of peptidoglycan cross-links in the bacterial cell wall. The enzyme lysozyme, found in human tears, also digests the cell wall of bacteria and is the body's main defense against eye infections.

What does gram-positive bacteria have?

thick cell wall containing many layers of peptidoglycan and teichoic acids

What can be endotoxins called?

Lipopolysaccharides

Why gram-negative cell bacteria is more toxic than gram-positive bacteria?

polysaccharides and lipid A

What can different structure of the cell walls of bacteria effect?

differences in antibiotic susceptibility

What is the main defense of human body against eye infections?

enzyme lysozyme, found in human tears


Acid-fast bacteria, such as Mycobacteria, are resistant to decolorization by acids during staining procedures. The high mycolic acid content of Mycobacteria, is responsible for the staining pattern of poor absorption followed by high retention. The most common staining technique used to identify acid-fast bacteria is the Ziehl-Neelsen stain or acid-fast stain, in which the acid-fast bacilli are stained bright-red and stand out clearly against a blue background. L-form bacteria are strains of bacteria that lack cell walls. The main pathogenic bacteria in this class is Mycoplasma (not to be confused with Mycobacteria).

What helps Mycobacteria be resistant to decolorization?

high mycolic acid content

What is mycolic acid is responsible for in Mycobacteria?

staining pattern of poor absorption followed by high retention.

What is the most typical staining technique used to identify acid-fast bacteria?

Ziehl-Neelsen stain

What is the main pathogenic bacteria in L-form class ?

Mycoplasma


Fimbriae (sometimes called "attachment pili") are fine filaments of protein, usually 2–10 nanometres in diameter and up to several micrometers in length. They are distributed over the surface of the cell, and resemble fine hairs when seen under the electron microscope. Fimbriae are believed to be involved in attachment to solid surfaces or to other cells, and are essential for the virulence of some bacterial pathogens. Pili (sing. pilus) are cellular appendages, slightly larger than fimbriae, that can transfer genetic material between bacterial cells in a process called conjugation where they are called conjugation pili or "sex pili" (see bacterial genetics, below). They can also generate movement where they are called type IV pili (see movement, below).

What are fimbriae?

fine filaments of protein

What is the diameter of fimbriae?

2–10 nanometres

What are fimbriae liable for?

involved in attachment to solid surfaces or to other cells

What are pili?

cellular appendages


Certain genera of Gram-positive bacteria, such as Bacillus, Clostridium, Sporohalobacter, Anaerobacter, and Heliobacterium, can form highly resistant, dormant structures called endospores. In almost all cases, one endospore is formed and this is not a reproductive process, although Anaerobacter can make up to seven endospores in a single cell. Endospores have a central core of cytoplasm containing DNA and ribosomes surrounded by a cortex layer and protected by an impermeable and rigid coat. Dipicolinic acid is a chemical compound that composes 5% to 15% of the dry weight of bacterial spores. It is implicated as responsible for the heat resistance of the endospore.

What are highly resistant dormant structures of certain gram-positive bacteria called?

endospores

Is creating endospore a reproductive process?

is not a reproductive process

What are ribosomes in endospores are enclosed in?

cortex layer

What chemical compound comprises 5% to 15% of the dry weight of bacterial spores?

Dipicolinic acid


Endospores show no detectable metabolism and can survive extreme physical and chemical stresses, such as high levels of UV light, gamma radiation, detergents, disinfectants, heat, freezing, pressure, and desiccation. In this dormant state, these organisms may remain viable for millions of years, and endospores even allow bacteria to survive exposure to the vacuum and radiation in space. According to scientist Dr. Steinn Sigurdsson, "There are viable bacterial spores that have been found that are 40 million years old on Earth — and we know they're very hardened to radiation." Endospore-forming bacteria can also cause disease: for example, anthrax can be contracted by the inhalation of Bacillus anthracis endospores, and contamination of deep puncture wounds with Clostridium tetani endospores causes tetanus.

Is there a metabolism in endospores?

show no detectable metabolism

What extreme physical and chemical stresses can endospores endure?

UV light, gamma radiation, detergents, disinfectants, heat, freezing, pressure

How long can endospores of bacteria stay alive in dormant state?

for millions of years

What endospore-forming bacteria can cause tetanus disease?

Clostridium tetani


Bacteria exhibit an extremely wide variety of metabolic types. The distribution of metabolic traits within a group of bacteria has traditionally been used to define their taxonomy, but these traits often do not correspond with modern genetic classifications. Bacterial metabolism is classified into nutritional groups on the basis of three major criteria: the kind of energy used for growth, the source of carbon, and the electron donors used for growth. An additional criterion of respiratory microorganisms are the electron acceptors used for aerobic or anaerobic respiration.

What is commonly used to determine taxonomy of bacteria?

The distribution of metabolic traits

How is bacterial metabolism determined?

nutritional groups

What are three main criterias of bacterial metabolism?

the kind of energy used for growth, the source of carbon, and the electron donors

What are electron acceptors accountable for?

aerobic or anaerobic respiration


Carbon metabolism in bacteria is either heterotrophic, where organic carbon compounds are used as carbon sources, or autotrophic, meaning that cellular carbon is obtained by fixing carbon dioxide. Heterotrophic bacteria include parasitic types. Typical autotrophic bacteria are phototrophic cyanobacteria, green sulfur-bacteria and some purple bacteria, but also many chemolithotrophic species, such as nitrifying or sulfur-oxidising bacteria. Energy metabolism of bacteria is either based on phototrophy, the use of light through photosynthesis, or based on chemotrophy, the use of chemical substances for energy, which are mostly oxidised at the expense of oxygen or alternative electron acceptors (aerobic/anaerobic respiration).

How does heterotrophic carbon metabolism occur?

organic carbon compounds are used as carbon sources

When carbon metabolism is called autotrophic?

cellular carbon is obtained by fixing carbon dioxide

What category do parasitic bacteria fall into?

Heterotrophic bacteria

Green sulfur-bacteria is typical representative of what type of bacteria?

autotrophic bacteria

What is chemotrophy ?

the use of chemical substances for energy


Bacteria are further divided into lithotrophs that use inorganic electron donors and organotrophs that use organic compounds as electron donors. Chemotrophic organisms use the respective electron donors for energy conservation (by aerobic/anaerobic respiration or fermentation) and biosynthetic reactions (e.g., carbon dioxide fixation), whereas phototrophic organisms use them only for biosynthetic purposes. Respiratory organisms use chemical compounds as a source of energy by taking electrons from the reduced substrate and transferring them to a terminal electron acceptor in a redox reaction. This reaction releases energy that can be used to synthesise ATP and drive metabolism. In aerobic organisms, oxygen is used as the electron acceptor. In anaerobic organisms other inorganic compounds, such as nitrate, sulfate or carbon dioxide are used as electron acceptors. This leads to the ecologically important processes of denitrification, sulfate reduction, and acetogenesis, respectively.

What do lithotrophs use ?

inorganic electron donors

What type of electron donors organotrophs use?

organic compounds

What do respiratory organisms use as electron donors?

chemical compounds

In what organisms is oxygen used as eelectron acceptor?

anaerobic organisms


These processes are also important in biological responses to pollution; for example, sulfate-reducing bacteria are largely responsible for the production of the highly toxic forms of mercury (methyl- and dimethylmercury) in the environment. Non-respiratory anaerobes use fermentation to generate energy and reducing power, secreting metabolic by-products (such as ethanol in brewing) as waste. Facultative anaerobes can switch between fermentation and different terminal electron acceptors depending on the environmental conditions in which they find themselves.

What is sulfate-reducing bacteria accountable for?

the production of the highly toxic forms of mercury

What is the by-product of non-repiratory anaerobes?

ethanol

How can anaerobes adjust to the surrounding environment?

can switch between fermentation and different terminal electron acceptors


Lithotrophic bacteria can use inorganic compounds as a source of energy. Common inorganic electron donors are hydrogen, carbon monoxide, ammonia (leading to nitrification), ferrous iron and other reduced metal ions, and several reduced sulfur compounds. In unusual circumstances, the gas methane can be used by methanotrophic bacteria as both a source of electrons and a substrate for carbon anabolism. In both aerobic phototrophy and chemolithotrophy, oxygen is used as a terminal electron acceptor, whereas under anaerobic conditions inorganic compounds are used instead. Most lithotrophic organisms are autotrophic, whereas organotrophic organisms are heterotrophic.

What are hydrogen and carbon monoxide for Lithotrophic bacteria?

Common inorganic electron donors

How can gas methane be used in exceptional set of conditions by methanotrophic bacteria?

both a source of electrons and a substrate for carbon anabolism

What is the main element for aerobic photorophy?

oxygen


Regardless of the type of metabolic process they employ, the majority of bacteria are able to take in raw materials only in the form of relatively small molecules, which enter the cell by diffusion or through molecular channels in cell membranes. The Planctomycetes are the exception (as they are in possessing membranes around their nuclear material). It has recently been shown that Gemmata obscuriglobus is able to take in large molecules via a process that in some ways resembles endocytosis, the process used by eukaryotic cells to engulf external items.

How can bacteria obtain raw materials from the environment?

in the form of relatively small molecules

What chemical process  helps bacteria to absorb raw materials?

diffusion

What process is used by eukaryotic cells to absorb external items?

endocytosis

What part of bacteria cell is used during diffusion?

molecular channels in cell membranes


Unlike in multicellular organisms, increases in cell size (cell growth) and reproduction by cell division are tightly linked in unicellular organisms. Bacteria grow to a fixed size and then reproduce through binary fission, a form of asexual reproduction. Under optimal conditions, bacteria can grow and divide extremely rapidly, and bacterial populations can double as quickly as every 9.8 minutes. In cell division, two identical clone daughter cells are produced. Some bacteria, while still reproducing asexually, form more complex reproductive structures that help disperse the newly formed daughter cells. Examples include fruiting body formation by Myxobacteria and aerial hyphae formation by Streptomyces, or budding. Budding involves a cell forming a protrusion that breaks away and produces a daughter cell.

How size and reproduction are linked in bacteria?

Bacteria grow to a fixed size and then reproduce

How does bacteria reproduce?

through binary fission

If the conditions are right how long does it take for bacteria to reproduce?

divide extremely rapidly

What are produced in cell division?

two identical clone daughter cells


In the laboratory, bacteria are usually grown using solid or liquid media. Solid growth media, such as agar plates, are used to isolate pure cultures of a bacterial strain. However, liquid growth media are used when measurement of growth or large volumes of cells are required. Growth in stirred liquid media occurs as an even cell suspension, making the cultures easy to divide and transfer, although isolating single bacteria from liquid media is difficult. The use of selective media (media with specific nutrients added or deficient, or with antibiotics added) can help identify specific organisms.

In what environment are bacteria being cultivated in labs?

solid or liquid media

What is typical solid setting?

agar plates

Which media is preffered to grow larger volumes of bacteria?

liquid growth media

Which environment is better to isolate a single example of bacteria strain?

agar plates

What can help to indentify specific bacteria?

The use of selective media


Most laboratory techniques for growing bacteria use high levels of nutrients to produce large amounts of cells cheaply and quickly. However, in natural environments, nutrients are limited, meaning that bacteria cannot continue to reproduce indefinitely. This nutrient limitation has led the evolution of different growth strategies (see r/K selection theory). Some organisms can grow extremely rapidly when nutrients become available, such as the formation of algal (and cyanobacterial) blooms that often occur in lakes during the summer. Other organisms have adaptations to harsh environments, such as the production of multiple antibiotics by Streptomyces that inhibit the growth of competing microorganisms. In nature, many organisms live in communities (e.g., biofilms) that may allow for increased supply of nutrients and protection from environmental stresses. These relationships can be essential for growth of a particular organism or group of organisms (syntrophy).

What is the simple way of producing large volume of bacteria cells?

high levels of nutrients

What caused the evolution of different growth strategies in bacteria?

nutrients are limited

What do algal bacteria if nutrients are available?

grow extremely rapidly

What can create a subsequent increase of nutrients in natural environment?

biofilms


Bacterial growth follows four phases. When a population of bacteria first enter a high-nutrient environment that allows growth, the cells need to adapt to their new environment. The first phase of growth is the lag phase, a period of slow growth when the cells are adapting to the high-nutrient environment and preparing for fast growth. The lag phase has high biosynthesis rates, as proteins necessary for rapid growth are produced. The second phase of growth is the log phase, also known as the logarithmic or exponential phase. The log phase is marked by rapid exponential growth. The rate at which cells grow during this phase is known as the growth rate (k), and the time it takes the cells to double is known as the generation time (g). During log phase, nutrients are metabolised at maximum speed until one of the nutrients is depleted and starts limiting growth. The third phase of growth is the stationary phase and is caused by depleted nutrients. The cells reduce their metabolic activity and consume non-essential cellular proteins. The stationary phase is a transition from rapid growth to a stress response state and there is increased expression of genes involved in DNA repair, antioxidant metabolism and nutrient transport. The final phase is the death phase where the bacteria run out of nutrients and die.

How many phase are in the growth of bacteria?

four phases

What is the first stage of bacteria adaptation?

lag phase

What is the second phase of bacteria growth known for?

rapid exponential growth

What is called the third statge of growth of bacteria?

stationary phase

The absence of what causes the last stage of bacteria growth?

nutrients


Most bacteria have a single circular chromosome that can range in size from only 160,000 base pairs in the endosymbiotic bacteria Candidatus Carsonella ruddii, to 12,200,000 base pairs in the soil-dwelling bacteria Sorangium cellulosum. Spirochaetes of the genus Borrelia are a notable exception to this arrangement, with bacteria such as Borrelia burgdorferi, the cause of Lyme disease, containing a single linear chromosome. The genes in bacterial genomes are usually a single continuous stretch of DNA and although several different types of introns do exist in bacteria, these are much rarer than in eukaryotes.

What shape is chromosome of bacteria?

circular chromosome

What bacteria is an exception to single circular chromosome rule?

Spirochaetes of the genus Borrelia

What bacteria is responsible for Lyme disease?

Borrelia burgdorferi

How does chromosome of Borrelia burgdoferi look like?

single linear chromosome


Bacteria, as asexual organisms, inherit identical copies of their parent's genes (i.e., they are clonal). However, all bacteria can evolve by selection on changes to their genetic material DNA caused by genetic recombination or mutations. Mutations come from errors made during the replication of DNA or from exposure to mutagens. Mutation rates vary widely among different species of bacteria and even among different clones of a single species of bacteria. Genetic changes in bacterial genomes come from either random mutation during replication or "stress-directed mutation", where genes involved in a particular growth-limiting process have an increased mutation rate.

What makes bacteria an asexual organism?

inherit identical copies of their parent's genes

What can cause mutation in bacteria?

changes to their genetic material DNA

What are two ways changes to DNA of bacteria can occur?

random mutation during replication or "stress-directed mutation"


Transduction of bacterial genes by bacteriophage appears to be a consequence of infrequent errors during intracellular assembly of virus particles, rather than a bacterial adaptation. Conjugation, in the much-studied E. coli system is determined by plasmid genes, and is an adaptation for transferring copies of the plasmid from one bacterial host to another. It is seldom that a conjugative plasmid integrates into the host bacterial chromosome, and subsequently transfers part of the host bacterial DNA to another bacterium. Plasmid-mediated transfer of host bacterial DNA also appears to be an accidental process rather than a bacterial adaptation.

What is the aftermath of infrequent errors during intracellular assembly of virus particles?

Transduction of bacterial genes

What is the result of bacterial adaptation of E.coli bacteria host and plasmid of another bacteria?

Conjugation

How does conjugation take place?

conjugative plasmid integrates into the host bacterial chromosome

Is conjugation a common bacterial adaptation?

It is seldom


Transformation, unlike transduction or conjugation, depends on numerous bacterial gene products that specifically interact to perform this complex process, and thus transformation is clearly a bacterial adaptation for DNA transfer. In order for a bacterium to bind, take up and recombine donor DNA into its own chromosome, it must first enter a special physiological state termed competence (see Natural competence). In Bacillus subtilis, about 40 genes are required for the development of competence. The length of DNA transferred during B. subtilis transformation can be between a third of a chromosome up to the whole chromosome. Transformation appears to be common among bacterial species, and thus far at least 60 species are known to have the natural ability to become competent for transformation. The development of competence in nature is usually associated with stressful environmental conditions, and seems to be an adaptation for facilitating repair of DNA damage in recipient cells.

What does transformation of bacteria depends on?

numerous bacterial gene products

How simple is the process of transformation?

this complex process

What is the first requirement in order for bacteria to bind and recombine with other bacteria's DNA

enter a special physiological state termed competence

How big can be the transformation level?

between a third of a chromosome up to the whole chromosome

How rare is the transformation among bacteria organisms?

common


In ordinary circumstances, transduction, conjugation, and transformation involve transfer of DNA between individual bacteria of the same species, but occasionally transfer may occur between individuals of different bacterial species and this may have significant consequences, such as the transfer of antibiotic resistance. In such cases, gene acquisition from other bacteria or the environment is called horizontal gene transfer and may be common under natural conditions. Gene transfer is particularly important in antibiotic resistance as it allows the rapid transfer of resistance genes between different pathogens.

Between what species do usually transduction, conjugation and transformation take place?

the same species

What are the consequences of transfer between different species of bacteria?

transfer of antibiotic resistance

What is horizontal gene transfer?

gene acquisition from other bacteria or the environment


Bacteriophages are viruses that infect bacteria. Many types of bacteriophage exist, some simply infect and lyse their host bacteria, while others insert into the bacterial chromosome. A bacteriophage can contain genes that contribute to its host's phenotype: for example, in the evolution of Escherichia coli O157:H7 and Clostridium botulinum, the toxin genes in an integrated phage converted a harmless ancestral bacterium into a lethal pathogen. Bacteria resist phage infection through restriction modification systems that degrade foreign DNA, and a system that uses CRISPR sequences to retain fragments of the genomes of phage that the bacteria have come into contact with in the past, which allows them to block virus replication through a form of RNA interference. This CRISPR system provides bacteria with acquired immunity to infection.

What are Bacteriophages?

viruses that infect bacteria

What can viruses do to bacteria?

infect and lyse their host bacteria

What can happen if Bacteriophage contain genes of host's phenotype?

lethal pathogen

How can bacteria resist virus DNA?

CRISPR system provides bacteria with acquired immunity


Bacterial species differ in the number and arrangement of flagella on their surface; some have a single flagellum (monotrichous), a flagellum at each end (amphitrichous), clusters of flagella at the poles of the cell (lophotrichous), while others have flagella distributed over the entire surface of the cell (peritrichous). The bacterial flagella is the best-understood motility structure in any organism and is made of about 20 proteins, with approximately another 30 proteins required for its regulation and assembly. The flagellum is a rotating structure driven by a reversible motor at the base that uses the electrochemical gradient across the membrane for power. This motor drives the motion of the filament, which acts as a propeller.

What is monotrichous?

single flagellum

If bacteria has flagellum at each end what is the name of the species?

amphitrichous

When flagellum is distributed throughout the surface of the cell?

peritrichous

How many proteins is typical flagellum consist os?

20 proteins

How does flagellum function within the cell?

uses the electrochemical gradient across the membrane


Classification seeks to describe the diversity of bacterial species by naming and grouping organisms based on similarities. Bacteria can be classified on the basis of cell structure, cellular metabolism or on differences in cell components, such as DNA, fatty acids, pigments, antigens and quinones. While these schemes allowed the identification and classification of bacterial strains, it was unclear whether these differences represented variation between distinct species or between strains of the same species. This uncertainty was due to the lack of distinctive structures in most bacteria, as well as lateral gene transfer between unrelated species. Due to lateral gene transfer, some closely related bacteria can have very different morphologies and metabolisms. To overcome this uncertainty, modern bacterial classification emphasizes molecular systematics, using genetic techniques such as guanine cytosine ratio determination, genome-genome hybridization, as well as sequencing genes that have not undergone extensive lateral gene transfer, such as the rRNA gene. Classification of bacteria is determined by publication in the International Journal of Systematic Bacteriology, and Bergey's Manual of Systematic Bacteriology. The International Committee on Systematic Bacteriology (ICSB) maintains international rules for the naming of bacteria and taxonomic categories and for the ranking of them in the International Code of Nomenclature of Bacteria.

How can we classify the vast variety of bacterial species?

grouping organisms based on similarities

Can classification be helpful in determining differences between distinct species?

unclear

What supports the uncertainty in classification between the same kind of bacteria?

lack of distinctive structures in most bacteria,

What can lateral gene transfer create in bacteria?

different morphologies and metabolisms

What is the way modern classification tries to determine species?

emphasizes molecular systematics


The term "bacteria" was traditionally applied to all microscopic, single-cell prokaryotes. However, molecular systematics showed prokaryotic life to consist of two separate domains, originally called Eubacteria and Archaebacteria, but now called Bacteria and Archaea that evolved independently from an ancient common ancestor. The archaea and eukaryotes are more closely related to each other than either is to the bacteria. These two domains, along with Eukarya, are the basis of the three-domain system, which is currently the most widely used classification system in microbiolology. However, due to the relatively recent introduction of molecular systematics and a rapid increase in the number of genome sequences that are available, bacterial classification remains a changing and expanding field. For example, a few biologists argue that the Archaea and Eukaryotes evolved from Gram-positive bacteria.

What would original term "bacteria" determine?

all microscopic, single-cell prokaryotes

What are two main groups of prokaryotic organisms are divided into?

Eubacteria and Archaebacteria

What groups of organisms are closely related to each other?

archaea and eukaryotes

What domain system is commonly used nowdays to classify microorganisms?

three-domain system


The Gram stain, developed in 1884 by Hans Christian Gram, characterises bacteria based on the structural characteristics of their cell walls. The thick layers of peptidoglycan in the "Gram-positive" cell wall stain purple, while the thin "Gram-negative" cell wall appears pink. By combining morphology and Gram-staining, most bacteria can be classified as belonging to one of four groups (Gram-positive cocci, Gram-positive bacilli, Gram-negative cocci and Gram-negative bacilli). Some organisms are best identified by stains other than the Gram stain, particularly mycobacteria or Nocardia, which show acid-fastness on Ziehl–Neelsen or similar stains. Other organisms may need to be identified by their growth in special media, or by other techniques, such as serology.

What was developed by Hans Christian  Gram?

The Gram stain

What year was the Grahm stain was developed?

What color do Gram positive bacteria cell walls turn to after being stained?

purple

What color is typical for Gram-negative bacteria after staining?

pink

What stain shows better test results on Norcadia bacteria?

Ziehl–Neelsen


As with bacterial classification, identification of bacteria is increasingly using molecular methods. Diagnostics using DNA-based tools, such as polymerase chain reaction, are increasingly popular due to their specificity and speed, compared to culture-based methods. These methods also allow the detection and identification of "viable but nonculturable" cells that are metabolically active but non-dividing. However, even using these improved methods, the total number of bacterial species is not known and cannot even be estimated with any certainty. Following present classification, there are a little less than 9,300 known species of prokaryotes, which includes bacteria and archaea; but attempts to estimate the true number of bacterial diversity have ranged from 107 to 109 total species – and even these diverse estimates may be off by many orders of magnitude.

What technique has becoming more popular in classification of bacteria?

molecular methods

What tool does DNA based diagnostics use?

polymerase chain reaction

What else can molecular methods of classification reveal?

identification of "viable but nonculturable" cells

Can new methods determine a total number of bacteria species?

cannot even be estimated with any certainty


Some species of bacteria kill and then consume other microorganisms, these species are called predatory bacteria. These include organisms such as Myxococcus xanthus, which forms swarms of cells that kill and digest any bacteria they encounter. Other bacterial predators either attach to their prey in order to digest them and absorb nutrients, such as Vampirovibrio chlorellavorus, or invade another cell and multiply inside the cytosol, such as Daptobacter. These predatory bacteria are thought to have evolved from saprophages that consumed dead microorganisms, through adaptations that allowed them to entrap and kill other organisms.

Why are certain bacteria called predatory?

bacteria kill and then consume other microorganisms

Which way do Vampirovibrio absorb nutrients of other microorganisms?

attach to their prey in order to digest them

What technique do Daptobacter use in order to kill other microorganism?

invade another cell and multiply inside the cytosol

Where do Daptobacter bacteria come from?

saprophages


Certain bacteria form close spatial associations that are essential for their survival. One such mutualistic association, called interspecies hydrogen transfer, occurs between clusters of anaerobic bacteria that consume organic acids, such as butyric acid or propionic acid, and produce hydrogen, and methanogenic Archaea that consume hydrogen. The bacteria in this association are unable to consume the organic acids as this reaction produces hydrogen that accumulates in their surroundings. Only the intimate association with the hydrogen-consuming Archaea keeps the hydrogen concentration low enough to allow the bacteria to grow.

What helps bacteria to survive?

close spatial associations

What kind of bacteria can form interspecies hydrogen transfer?

anaerobic bacteria

What do anaerobic bacteria consume?

butyric acid or propionic acid


In soil, microorganisms that reside in the rhizosphere (a zone that includes the root surface and the soil that adheres to the root after gentle shaking) carry out nitrogen fixation, converting nitrogen gas to nitrogenous compounds. This serves to provide an easily absorbable form of nitrogen for many plants, which cannot fix nitrogen themselves. Many other bacteria are found as symbionts in humans and other organisms. For example, the presence of over 1,000 bacterial species in the normal human gut flora of the intestines can contribute to gut immunity, synthesise vitamins, such as folic acid, vitamin K and biotin, convert sugars to lactic acid (see Lactobacillus), as well as fermenting complex undigestible carbohydrates. The presence of this gut flora also inhibits the growth of potentially pathogenic bacteria (usually through competitive exclusion) and these beneficial bacteria are consequently sold as probiotic dietary supplements.

Where do bacteria stay in soil?

rhizosphere

What do bacteria do in soil?

converting nitrogen gas to nitrogenous compounds

How does the conversion help the vegetation?

provide an easily absorbable form of nitrogen

What is the amount of bacteria in human intestines?

over 1,000 bacterial species

How does gut flora prevent growth of pathogenic bacteria?

through competitive exclusion


If bacteria form a parasitic association with other organisms, they are classed as pathogens. Pathogenic bacteria are a major cause of human death and disease and cause infections such as tetanus, typhoid fever, diphtheria, syphilis, cholera, foodborne illness, leprosy and tuberculosis. A pathogenic cause for a known medical disease may only be discovered many years after, as was the case with Helicobacter pylori and peptic ulcer disease. Bacterial diseases are also important in agriculture, with bacteria causing leaf spot, fire blight and wilts in plants, as well as Johne's disease, mastitis, salmonella and anthrax in farm animals.

What are the pathogenes?

bacteria form a parasitic association with other organisms

What can pathogenes cause?

human death and disease

Can cause for most pathogenic diseases be found soon?

may only be discovered many years after


Each species of pathogen has a characteristic spectrum of interactions with its human hosts. Some organisms, such as Staphylococcus or Streptococcus, can cause skin infections, pneumonia, meningitis and even overwhelming sepsis, a systemic inflammatory response producing shock, massive vasodilation and death. Yet these organisms are also part of the normal human flora and usually exist on the skin or in the nose without causing any disease at all. Other organisms invariably cause disease in humans, such as the Rickettsia, which are obligate intracellular parasites able to grow and reproduce only within the cells of other organisms. One species of Rickettsia causes typhus, while another causes Rocky Mountain spotted fever. Chlamydia, another phylum of obligate intracellular parasites, contains species that can cause pneumonia, or urinary tract infection and may be involved in coronary heart disease. Finally, some species, such as Pseudomonas aeruginosa, Burkholderia cenocepacia, and Mycobacterium avium, are opportunistic pathogens and cause disease mainly in people suffering from immunosuppression or cystic fibrosis.

How pathogenes interact with it's human host?

pathogen has a characteristic spectrum of interactions

Can all bacteria in human body  be harmful?

exist on the skin or in the nose without causing any disease

Which bacteria cause Rocky Mountain spotted fever disiease?

species of Rickettsia


Bacterial infections may be treated with antibiotics, which are classified as bacteriocidal if they kill bacteria, or bacteriostatic if they just prevent bacterial growth. There are many types of antibiotics and each class inhibits a process that is different in the pathogen from that found in the host. An example of how antibiotics produce selective toxicity are chloramphenicol and puromycin, which inhibit the bacterial ribosome, but not the structurally different eukaryotic ribosome. Antibiotics are used both in treating human disease and in intensive farming to promote animal growth, where they may be contributing to the rapid development of antibiotic resistance in bacterial populations. Infections can be prevented by antiseptic measures such as sterilizing the skin prior to piercing it with the needle of a syringe, and by proper care of indwelling catheters. Surgical and dental instruments are also sterilized to prevent contamination by bacteria. Disinfectants such as bleach are used to kill bacteria or other pathogens on surfaces to prevent contamination and further reduce the risk of infection.

What type of antibiotics called bacterocidal?

if they kill bacteria

What kind of antibiotics are used for prevention of bacterial growth

bacteriostatic

Besides in treating human disease where else are antibiotics used?

in intensive farming to promote animal growth

What is the drawback of using antibiotics if agriculture?

rapid development of antibiotic resistance in bacterial populations

What is common prevention method of infections in medicine?

sterilizing


The ability of bacteria to degrade a variety of organic compounds is remarkable and has been used in waste processing and bioremediation. Bacteria capable of digesting the hydrocarbons in petroleum are often used to clean up oil spills. Fertilizer was added to some of the beaches in Prince William Sound in an attempt to promote the growth of these naturally occurring bacteria after the 1989 Exxon Valdez oil spill. These efforts were effective on beaches that were not too thickly covered in oil. Bacteria are also used for the bioremediation of industrial toxic wastes. In the chemical industry, bacteria are most important in the production of enantiomerically pure chemicals for use as pharmaceuticals or agrichemicals.

What quality of bacteria is being widely used re-cyling?

ability of bacteria to degrade a variety of organic compounds

What is being used in cleaning up oil spills?

Bacteria

What other way is bacteria aiding to nature?

used for the bioremediation


Because of their ability to quickly grow and the relative ease with which they can be manipulated, bacteria are the workhorses for the fields of molecular biology, genetics and biochemistry. By making mutations in bacterial DNA and examining the resulting phenotypes, scientists can determine the function of genes, enzymes and metabolic pathways in bacteria, then apply this knowledge to more complex organisms. This aim of understanding the biochemistry of a cell reaches its most complex expression in the synthesis of huge amounts of enzyme kinetic and gene expression data into mathematical models of entire organisms. This is achievable in some well-studied bacteria, with models of Escherichia coli metabolism now being produced and tested. This understanding of bacterial metabolism and genetics allows the use of biotechnology to bioengineer bacteria for the production of therapeutic proteins, such as insulin, growth factors, or antibodies.

What sciences use bacteria?

molecular biology, genetics and biochemistry


Bacteria were first observed by the Dutch microscopist Antonie van Leeuwenhoek in 1676, using a single-lens microscope of his own design. He then published his observations in a series of letters to the Royal Society of London. Bacteria were Leeuwenhoek's most remarkable microscopic discovery. They were just at the limit of what his simple lenses could make out and, in one of the most striking hiatuses in the history of science, no one else would see them again for over a century. Only then were his by-then-largely-forgotten observations of bacteria — as opposed to his famous "animalcules" (spermatozoa) — taken seriously.

When was the first time bacteria were observed?

Who discovered bacteria?

Dutch microscopist Antonie van Leeuwenhoek

How was he able to see bacteria?

using a single-lens microscope of his own design

How long did it take for his discovery to be taken seriously?

over a century


Though it was known in the nineteenth century that bacteria are the cause of many diseases, no effective antibacterial treatments were available. In 1910, Paul Ehrlich developed the first antibiotic, by changing dyes that selectively stained Treponema pallidum — the spirochaete that causes syphilis — into compounds that selectively killed the pathogen. Ehrlich had been awarded a 1908 Nobel Prize for his work on immunology, and pioneered the use of stains to detect and identify bacteria, with his work being the basis of the Gram stain and the Ziehl–Neelsen stain.

When was the first antibiotic discovered?

In 1910

Who was the creator of antibiotic?

Paul Ehrlich

What bacteria did he treat first?

Treponema pallidum

How was his discovery aknowledged?

had been awarded a 1908 Nobel Prize

Who based their research on Enrlich's stains works?

Gram stain and the Ziehl–Neelsen


When the board has no embedded components it is more correctly called a printed wiring board (PWB) or etched wiring board. However, the term printed wiring board has fallen into disuse. A PCB populated with electronic components is called a printed circuit assembly (PCA), printed circuit board assembly or PCB assembly (PCBA). The IPC preferred term for assembled boards is circuit card assembly (CCA), and for assembled backplanes it is backplane assemblies. The term PCB is used informally both for bare and assembled boards.

What's the more appropriate, but mostly unused, name for a printed circuit board when it doesn't have embedded components?

printed wiring board

What's the abbreviation for a printed wiring board?

PWB

What would we call a printed circuit board with embedded electronics, abbreviated PCA?

printed circuit assembly

What organization likes the term "circuit card assembly" for boards that have already been assembled?

IPC

What abbreviation would the IPC use for an assembled circuit board?

CCA

When the board has embedded components it is called what?

I'm not sure.

A painted wiring board can also be called what?

I'm not sure.

The term painted wiring board has fallen into what?

I'm not sure.

The IPC preferred term for assembled bags is what?

I'm not sure.

The IPC preferred term for assembled backplates is what?

I'm not sure.


Initially PCBs were designed manually by creating a photomask on a clear mylar sheet, usually at two or four times the true size. Starting from the schematic diagram the component pin pads were laid out on the mylar and then traces were routed to connect the pads. Rub-on dry transfers of common component footprints increased efficiency. Traces were made with self-adhesive tape. Pre-printed non-reproducing grids on the mylar assisted in layout. To fabricate the board, the finished photomask was photolithographically reproduced onto a photoresist coating on the blank copper-clad boards.

What did PCB designers used to employ on a mylar sheet?

photomask

In the old PCB design method, what was used to connect component pin pads?

traces

What were traces originally made out of?

self-adhesive tape

Designers would rub on a dry transfer of what to make the process of laying out components simpler?

common component footprints

What kind of metal coated the blank boards used to make PCBs?

copper

Initially PCBs were designed mechanically how?

I'm not sure.

Pin pads were laid out on the nylon and then what?

I'm not sure.

Self-adhesive mylar was used to make what?

I'm not sure.

Pre-printed reproducing grids on the mylar assisted in what?

I'm not sure.

Printed copper-clad boards were used to make what?

I'm not sure.


Panelization is a procedure whereby a number of PCBs are grouped for manufacturing onto a larger board - the panel. Usually a panel consists of a single design but sometimes multiple designs are mixed on a single panel. There are two types of panels: assembly panels - often called arrays - and bare board manufacturing panels. The assemblers often mount components on panels rather than single PCBs because this is efficient. The bare board manufactures always uses panels, not only for efficiency, but because of the requirements the plating process. Thus a manufacturing panel can consist of a grouping of individual PCBs or of arrays, depending on what must be delivered.

What process groups PCBs before transfer to a panel?

Panelization

Is it more common for panels to have a single design or many designs?

a single design

What type of panels can also be referred to as an "array?'

assembly panels

Besides assembly panels, what's the other type of panel?

bare board manufacturing panels

What step of the bare board manufacture would be impossible if panels weren't always used?

the plating process

Usually a panel consists of multiple designs, but sometimes what?

I'm not sure.

The two types of portals are what?

I'm not sure.

Depending on what must be discussed, a manufacturing panel can consist of what?

I'm not sure.

Assemblers often mount components on portals rather than single PCBs why?

I'm not sure.


The panel is eventually broken apart into individual PCBs; this is called depaneling. Separating the individual PCBs is frequently aided by drilling or routing perforations along the boundaries of the individual circuits, much like a sheet of postage stamps. Another method, which takes less space, is to cut V-shaped grooves across the full dimension of the panel. The individual PCBs can then be broken apart along this line of weakness. Today depaneling is often done by lasers which cut the board with no contact. Laser panelization reduces stress on the fragile circuits.

What is the process called whereby the individual PCBs are separated?

depaneling

What boundaries would you follow to separate PCBs on a panel?

individual circuits

What technology has made depaneling possible without needing to physically interact with the board?

lasers

What does the V-shaped groove method save?

space

What delicate component is less likely to be damaged if laser depanelization is used?

circuits

The panel is eventually merged into what?

I'm not sure.

The process of deadpanning is what?

I'm not sure.

Individual PCBs can be merged along what line?

I'm not sure.

In the old days, depaneling was often done how?

I'm not sure.


Subtractive methods remove copper from an entirely copper-coated board to leave only the desired copper pattern. In additive methods the pattern is electroplated onto a bare substrate using a complex process. The advantage of the additive method is that less material is needed and less waste is produced. In the full additive process the bare laminate is covered with a photosensitive film which is imaged (exposed to light through a mask and then developed which removes the unexposed film). The exposed areas are sensitized in a chemical bath, usually containing palladium and similar to that used for through hole plating which makes the exposed area capable of bonding metal ions. The laminate is then plated with copper in the sensitized areas. When the mask is stripped, the PCB is finished.

Do additive or subtractive methods use less raw materials?

additive

What chemical element is often present in the bath used to sensitive exposed film after it's been imaged?

palladium

What object is used to expose selected parts of the photosensitive film to light?

mask

In subtractive methods, what metal covers the board and is then partially removed?

copper

In the additive method, which parts of the laminate are plated with copper?

sensitized areas

The advantage of the subtractive method is that less what?

I'm not sure.

Bare laminate is placed on top of photosensitive film in what process?

I'm not sure.

The exposed areas are sensitized using plutonium in what process?

I'm not sure.

The laminate is plated with silver during what process?

I'm not sure.

When the PCB is stripped, what is finished?

I'm not sure.


Semi-additive is the most common process: The unpatterned board has a thin layer of copper already on it. A reverse mask is then applied. (Unlike a subtractive process mask, this mask exposes those parts of the substrate that will eventually become the traces.) Additional copper is then plated onto the board in the unmasked areas; copper may be plated to any desired weight. Tin-lead or other surface platings are then applied. The mask is stripped away and a brief etching step removes the now-exposed bare original copper laminate from the board, isolating the individual traces. Some single-sided boards which have plated-through holes are made in this way. General Electric made consumer radio sets in the late 1960s using additive boards.

In the semi-additive process, what do the areas exposed by the mask become at the end?

traces

What metal is used to plate the unmasked parts of the board in the semi-additive method?

copper

After the mask comes off of the board, what step takes off the original plating?

etching

What company used to make radios with additive boards in the mid-20th century?

General Electric

What weight of plating is possible with copper?

any

Fully additive is the most common what?

I'm not sure.

Additional silver is plated onto what?

I'm not sure.

Who made consumer radio sets in the late 1940s using additive boards?

I'm not sure.

The patterned board has a thin layer of what already on it?

I'm not sure.


The simplest method, used for small-scale production and often by hobbyists, is immersion etching, in which the board is submerged in etching solution such as ferric chloride. Compared with methods used for mass production, the etching time is long. Heat and agitation can be applied to the bath to speed the etching rate. In bubble etching, air is passed through the etchant bath to agitate the solution and speed up etching. Splash etching uses a motor-driven paddle to splash boards with etchant; the process has become commercially obsolete since it is not as fast as spray etching. In spray etching, the etchant solution is distributed over the boards by nozzles, and recirculated by pumps. Adjustment of the nozzle pattern, flow rate, temperature, and etchant composition gives predictable control of etching rates and high production rates.

What non-professionals might use immersion etching, since it's the easiest way to make a PCB?

hobbyists

Is the immersion etching process long or short compared to other production methods?

long

If you wanted to speed up the etching process, you could agitate the bath up or add what to it?

Heat

What funny name is used for the etching process where air is blown through the etching solution to get it moving around?

bubble etching

What's the fastest and most easily controlled process for etching?

spray etching

Immaculate etching is the process where what?

I'm not sure.

Etching time is short compared to what?

I'm not sure.

What gives unpredictable control of etching rates and high production rates?

I'm not sure.

Air is passed through the etchant bath to slow the etching in what process?

I'm not sure.


Multi-layer printed circuit boards have trace layers inside the board. This is achieved by laminating a stack of materials in a press by applying pressure and heat for a period of time. This results in an inseparable one piece product. For example, a four-layer PCB can be fabricated by starting from a two-sided copper-clad laminate, etch the circuitry on both sides, then laminate to the top and bottom pre-preg and copper foil. It is then drilled, plated, and etched again to get traces on top and bottom layers.

If you started with a two-sided laminate etched on either side, laminated to the top and bottom, and processed it again to get traces on the outside layers, how many layers would your final PCB have?

four

What makes up the inside of a multi-layer PCB?

trace layers

Pressure is one thing you need to apply to make a multi-layer PCB; what's the other thing?

heat

What tool is used to push the trace layers in a multi-layer PCB together?

press

Single-layer printed circuit boards have trace layers where?

I'm not sure.

A five-layer PCB can be fabricated how?

I'm not sure.

What kind of circuit boards result from applying pressure and cold air for a period of time?

I'm not sure.

A silver-clad laminate can be found in what kind of circuit board?

I'm not sure.

A five-layer PCB uses what kind of foil?

I'm not sure.


Holes through a PCB are typically drilled with small-diameter drill bits made of solid coated tungsten carbide. Coated tungsten carbide is recommended since many board materials are very abrasive and drilling must be high RPM and high feed to be cost effective. Drill bits must also remain sharp so as not to mar or tear the traces. Drilling with high-speed-steel is simply not feasible since the drill bits will dull quickly and thus tear the copper and ruin the boards. The drilling is performed by automated drilling machines with placement controlled by a drill tape or drill file. These computer-generated files are also called numerically controlled drill (NCD) files or "Excellon files". The drill file describes the location and size of each drilled hole.

What kind of drill bit do you need to drill holes in a PCB?

coated tungsten carbide

What kind of material sometimes used for drilling will lose sharpness quickly if used for PCBs?

high-speed-steel

What property do PCBs have that makes them tough to drill through?

abrasive

What does the "NCD" in "NCD files" mean?

numerically controlled drill

What's another name for NCD files that has an "x" in it?

Excellon files

Holes through a PBC are drilled how?

I'm not sure.

Drill bits must remain dull why?

I'm not sure.

Drilling with high-speed-steel is feasible why?

I'm not sure.

The dull file describes what?

I'm not sure.

Drilling must be low RPM and high feed to be what?

I'm not sure.


The hole walls for boards with two or more layers can be made conductive and then electroplated with copper to form plated-through holes.  These holes electrically connect the conducting layers of the PCB. For multi-layer boards, those with three layers or more, drilling typically produces a smear of the high temperature decomposition products of bonding agent in the laminate system. Before the holes can be plated through, this smear must be removed by a chemical de-smear process, or by plasma-etch. The de-smear process ensures that a good connection is made to the copper layers when the hole is plated through. On high reliability boards a process called etch-back is performed chemically with a potassium permanganate based etchant or plasma. The etch-back removes resin and the glass fibers so that the copper layers extend into the hole and as the hole is plated become integral with the deposited copper.

What do the hole walls in two-layer PCBs have to be before they can be electroplated?

conductive

What's the minimum number of layers a PCB can have to be considered "multi-layer"?

three

What process does a multi-layer PCB usually undergo before plating to make sure the layers have good connectivity with each other?

de-smear

What type of boards undergo the etch-back process?

high reliability

Etch-back removes glass fibers and what other material?

resin

What connects the conducting layers of the PAB?

I'm not sure.

Smears are removed with a chemical smear what?

I'm not sure.

The process used on low-reliability boards is called what?

I'm not sure.

The back-etch removes what?

I'm not sure.

What becomes integral with the deposited silver?

I'm not sure.


Matte solder is usually fused to provide a better bonding surface or stripped to bare copper. Treatments, such as benzimidazolethiol, prevent surface oxidation of bare copper. The places to which components will be mounted are typically plated, because untreated bare copper oxidizes quickly, and therefore is not readily solderable. Traditionally, any exposed copper was coated with solder by hot air solder levelling (HASL). The HASL finish prevents oxidation from the underlying copper, thereby guaranteeing a solderable surface. This solder was a tin-lead alloy, however new solder compounds are now used to achieve compliance with the RoHS directive in the EU and US, which restricts the use of lead. One of these lead-free compounds is SN100CL, made up of 99.3% tin, 0.7% copper, 0.05% nickel, and a nominal of 60ppm germanium.

What happens to untreated copper that makes it difficult to solder?

oxidizes

What chemical treatment will prevent bare copper from oxidizing?

benzimidazolethiol

What's the process by which bare copper gets covered in solder?

hot air solder levelling

What does hot air solder leveling ensure the coated copper will have?

solderable surface

What alloy can no longer be used in HASL because of restrictions on the use of one of its metal components?

tin-lead

Shiny solder is usually fused to do what?

I'm not sure.

What encourages surface oxidation of bare copper?

I'm not sure.

Traditionally, any exposed silver was coated with what?

I'm not sure.

The HASL finish encourages oxidation from what?

I'm not sure.

What is now used in compliance with the RoHS directive in the EU and China?

I'm not sure.


Other platings used are OSP (organic surface protectant), immersion silver (IAg), immersion tin, electroless nickel with immersion gold coating (ENIG), electroless nickel electroless palladium immersion gold (ENEPIG) and direct gold plating (over nickel). Edge connectors, placed along one edge of some boards, are often nickel plated then gold plated. Another coating consideration is rapid diffusion of coating metal into Tin solder. Tin forms intermetallics such as Cu5Sn6 and Ag3Cu that dissolve into the Tin liquidus or solidus(@50C), stripping surface coating or leaving voids.

What does OSP stand for?

organic surface protectant

What metal is often under the gold plating on edge connectors?

nickel

What's the abbreviation for immersion silver plating?

IAg

Ag3Cu is one intermetallic that tin forms; what's the other one?

What might the rapid diffusion of coating metal into tin solder leave in the surface coating?

voids

Main connectors, placed along one edge of some boards, are often what?

I'm not sure.

The only coating consideration is what?

I'm not sure.

What forms intermetallics such a Cu66n6?

I'm not sure.

Electroless silver with immersion gold coating (ENIG) is an example of what?

I'm not sure.

Electroless silver electroless palladium immersion gold (ENEPIG) is an example of what?

I'm not sure.


Electrochemical migration (ECM) is the growth of conductive metal filaments on or in a printed circuit board (PCB) under the influence of a DC voltage bias. Silver, zinc, and aluminum are known to grow whiskers under the influence of an electric field. Silver also grows conducting surface paths in the presence of halide and other ions, making it a poor choice for electronics use. Tin will grow "whiskers" due to tension in the plated surface. Tin-Lead or solder plating also grows whiskers, only reduced by the percentage Tin replaced. Reflow to melt solder or tin plate to relieve surface stress lowers whisker incidence. Another coating issue is tin pest, the transformation of tin to a powdery allotrope at low temperature.

What's the process whereby metal filaments are grown on or in a PCB via DC voltage?

Electrochemical migration

Along with silver and aluminum, what metal grows metal filaments when exposed to an electric field?

zinc

In addition to "whiskers," what does silver sprout around ions like halide?

conducting surface paths

What do scientist call the function whereby tin changes when it's very cold?

tin pest

What's present in plated surfaces that causes tin to grow metal filaments?

tension

What material is a good choice for electronics use?

I'm not sure.

Tin plast is what type of issue?

I'm not sure.

The transformation of silver to a powdery allotrope at low temperature is know as what?

I'm not sure.

AC voltage bias helps promote the growth of what?

I'm not sure.


Areas that should not be soldered may be covered with solder resist (solder mask). One of the most common solder resists used today is called "LPI" (liquid photoimageable solder mask).  A photo-sensitive coating is applied to the surface of the PWB, then exposed to light through the solder mask image film, and finally developed where the unexposed areas are washed away. Dry film solder mask is similar to the dry film used to image the PWB for plating or etching. After being laminated to the PWB surface it is imaged and develop as LPI. Once common but no longer commonly used because of its low accuracy and resolution is to screen print epoxy ink. Solder resist also provides protection from the environment.

If part of a PCB isn't solderable, what can be used instead?

solder resist

What's another term used for "solder resist"?

solder mask

What solder resist with a four-word name is a popular choice in the industry?

liquid photoimageable solder mask

What kind of coating gets applied to the PWB before light exposure?

photo-sensitive

What solder resist is so inaccurate that few choose it anymore?

screen print epoxy ink

Areas that should be soldered may be covered with what?

I'm not sure.

A photo-sensitive coating is applied beneath the surface of what?

I'm not sure.

Wet film solder mask is similar to what?

I'm not sure.

Screen print epoxy ink is commonly used why?

I'm not sure.

What doesn't provide protection from the environment?

I'm not sure.


Unpopulated boards are usually bare-board tested for "shorts" and "opens". A short is a connection between two points that should not be connected. An open is a missing connection between points that should be connected. For high-volume production a fixture or a rigid needle adapter is used to make contact with copper lands on the board. Building the adapter is a significant fixed cost and is only economical for high-volume or high-value production. For small or medium volume production flying probe testers are used where test probes are moved over the board by an XY drive to make contact with the copper lands. The CAM system instructs the electrical tester to apply a voltage to each contact point as required and to check that this voltage appears on the appropriate contact points and only on these.

What are bare-board tests looking for besides "opens"?

"shorts"

What's an absent connection that needs to be linked up on an unpopulated board called?

An open

What conductive metal are the lands on a circuit board made out of?

copper

What does a flying probe tester deliver to the contact points during testing?

voltage

What system tells the flying probe where to go and what to do?

CAM system

Populated boards are usually what?

I'm not sure.

A long is a connection between what?

I'm not sure.

A closed is a missing connection between what?

I'm not sure.

Building the adapter is low cost and economical for?

I'm not sure.


Often, through-hole and surface-mount construction must be combined in a single assembly because some required components are available only in surface-mount packages, while others are available only in through-hole packages. Another reason to use both methods is that through-hole mounting can provide needed strength for components likely to endure physical stress, while components that are expected to go untouched will take up less space using surface-mount techniques. For further comparison, see the SMT page.

Surface-mount is one type of construction used in PCB assembly; what's the other one?

through-hole

Which type of construction makes components that use more space?

through-hole

Which of the two kinds of construction is weaker under strain?

surface-mount

If you're building a circuit board that has a lot of components that won't be used, which construction would be better?

surface-mount

What must be combined in a multiple assembly?

I'm not sure.

Surface mount mounting can provide needed strength for what?

I'm not sure.

Components that are expected to be touched will take up what?

I'm not sure.

All required components are available only in what?

I'm not sure.


In boundary scan testing, test circuits integrated into various ICs on the board form temporary connections between the PCB traces to test that the ICs are mounted correctly. Boundary scan testing requires that all the ICs to be tested use a standard test configuration procedure, the most common one being the Joint Test Action Group (JTAG) standard. The JTAG test architecture provides a means to test interconnects between integrated circuits on a board without using physical test probes. JTAG tool vendors provide various types of stimulus and sophisticated algorithms, not only to detect the failing nets, but also to isolate the faults to specific nets, devices, and pins.

Do test circuits create permanent or temporary connections between traces?

temporary

What's the most frequently used test configuration procedure for ICs?

Joint Test Action Group

What would you avoid by using the Joint Test Action Group standard?

physical test probes

What component of the printed circuit board is appraised with boundary scan testing?

ICs

To whom would you go to acquire the algorithms you'd use for the Joint Test Action Group procedures?

JTAG tool vendors

Bouncing scan testing requires what?

I'm not sure.

The least common standard test configuration procedure is what?

I'm not sure.

JAG tool vendors provide various types of what?

I'm not sure.

The JAG test architecture provides a means to what?

I'm not sure.


PCBs intended for extreme environments often have a conformal coating, which is applied by dipping or spraying after the components have been soldered. The coat prevents corrosion and leakage currents or shorting due to condensation. The earliest conformal coats were wax; modern conformal coats are usually dips of dilute solutions of silicone rubber, polyurethane, acrylic, or epoxy. Another technique for applying a conformal coating is for plastic to be sputtered onto the PCB in a vacuum chamber. The chief disadvantage of conformal coatings is that servicing of the board is rendered extremely difficult.

If a PCB is intended for use in an setting with extreme conditions, what would probably be applied?

conformal coating

A conformal coating can be applied by spraying the PCB or by doing what else to it?

dipping

The conformal coating can prevent leaking, shorts, and what other type of moisture damage?

corrosion

What material was first used for conformal coating?

wax

What action is made much more difficult for boards that have a conformal coating?

servicing

PABs are intended for what type of environment?

I'm not sure.

What type of coat encourages corrosion?

I'm not sure.

The chief advantage to conformal coatings is what?

I'm not sure.

Which coatings are usually dips of dilute solutions of wax rubber?

I'm not sure.


Many assembled PCBs are static sensitive, and therefore must be placed in antistatic bags during transport. When handling these boards, the user must be grounded (earthed). Improper handling techniques might transmit an accumulated static charge through the board, damaging or destroying components. Even bare boards are sometimes static sensitive. Traces have become so fine that it's quite possible to blow an etch off the board (or change its characteristics) with a static charge. This is especially true on non-traditional PCBs such as MCMs and microwave PCBs.

What special protection are most PCBs shipped in?

antistatic bags

What's another term for "grounded" in the context of PCBs?

earthed

What force can easily change or even completely destroy an etch on a PCB?

static charge

What class of PCBs are even more susceptible to static than standard ones?

non-traditional

Non-traditional PCBs include microwave PCBs and what other type of board?

MCMs

Many assembled PABs are sensitive to what?

I'm not sure.

Proper handling techniques might transmit what?

I'm not sure.

What must be placed in static bags during transport?

I'm not sure.

An accumulated static charge though the user happens when what is done?

I'm not sure.


The first PCBs used through-hole technology, mounting electronic components by leads inserted through holes on one side of the board and soldered onto copper traces on the other side. Boards may be single-sided, with an unplated component side, or more compact double-sided boards, with components soldered on both sides. Horizontal installation of through-hole parts with two axial leads (such as resistors, capacitors, and diodes) is done by bending the leads 90 degrees in the same direction, inserting the part in the board (often bending leads located on the back of the board in opposite directions to improve the part's mechanical strength), soldering the leads, and trimming off the ends. Leads may be soldered either manually or by a wave soldering machine.

If a lead wasn't soldered manually, what device was used?

wave soldering machine

Which type of PCB construction technique was used first?

through-hole

In through-hole construction, what are the leads on the front attached to on the back?

copper traces

For boards with two sides, to what angle are leads bent to in order to install them horizontally?

90 degrees

What is improved by bending leads in opposite directions on the back of double-sided PCBs?

mechanical strength

Vertical installation of through-hole parts with two axial leads in done how?

I'm not sure.

Vertical installation is done by bending the leads what degrees?

I'm not sure.

Leads have to be soldered in what way?

I'm not sure.

A wave sewing machine can solder the what?

I'm not sure.


Through-hole manufacture adds to board cost by requiring many holes to be drilled accurately, and limits the available routing area for signal traces on layers immediately below the top layer on multi-layer boards since the holes must pass through all layers to the opposite side. Once surface-mounting came into use, small-sized SMD components were used where possible, with through-hole mounting only of components unsuitably large for surface-mounting due to power requirements or mechanical limitations, or subject to mechanical stress which might damage the PCB.

Which type of construction is more expensive?

Through-hole

What type of boards end up with limited routing space in through-hole manufacture?

multi-layer

What force might damage a PCB if large components are surface mounted?

mechanical stress

What components can be surface mounted to save space?

small-sized SMD components

A component might not be able to be made any smaller because of its mechanical limitations or what other need?

power requirements

What will not damage the PCB?

I'm not sure.

Mechanical signs will damage the what?

I'm not sure.

What increases the available routing area?

I'm not sure.

Large-sized SMD components were used when?

I'm not sure.


Surface-mount technology emerged in the 1960s, gained momentum in the early 1980s and became widely used by the mid-1990s. Components were mechanically redesigned to have small metal tabs or end caps that could be soldered directly onto the PCB surface, instead of wire leads to pass through holes. Components became much smaller and component placement on both sides of the board became more common than with through-hole mounting, allowing much smaller PCB assemblies with much higher circuit densities. Surface mounting lends itself well to a high degree of automation, reducing labor costs and greatly increasing production rates. Components can be supplied mounted on carrier tapes. Surface mount components can be about one-quarter to one-tenth of the size and weight of through-hole components, and passive components much cheaper; prices of semiconductor surface mount devices (SMDs) are determined more by the chip itself than the package, with little price advantage over larger packages. Some wire-ended components, such as 1N4148 small-signal switch diodes, are actually significantly cheaper than SMD equivalents.

When did surface-mount become a commonly used manufacturing process?

What did the new components with end tabs replace?

wire leads

What improvement is possible with surface-mounting that enables higher production and lower labor costs?

automation

What are SMDs?

surface mount devices

Is it the chip or the package that influences the price of an SMD more?

chip

What kind of technology emerged in the 1950s?

I'm not sure.

What became widely used in the 2090s?

I'm not sure.

What was redesigned to have small plastic tabs?

I'm not sure.

What lends itself well to a low degree of automation?

I'm not sure.

What are more expensive than SMD equivalents?

I'm not sure.


Each trace consists of a flat, narrow part of the copper foil that remains after etching. The resistance, determined by width and thickness, of the traces must be sufficiently low for the current the conductor will carry. Power and ground traces may need to be wider than signal traces. In a multi-layer board one entire layer may be mostly solid copper to act as a ground plane for shielding and power return. For microwave circuits, transmission lines can be laid out in the form of stripline and microstrip with carefully controlled dimensions to assure a consistent impedance. In radio-frequency and fast switching circuits the inductance and capacitance of the printed circuit board conductors become significant circuit elements, usually undesired; but they can be used as a deliberate part of the circuit design, obviating the need for additional discrete components.

What process is a trace left over from?

etching

Along with thickness, what determines the resistance of a trace?

width

What type of trace is often narrower than a ground trace?

signal

In a multi-layer board, what metal would a ground plane be mostly made out of?

copper

What type of circuits use a stripline and microstrip format?

microwave circuits

What consists of a wide, curved part of copper foil?

I'm not sure.

What needs to be narrower than signal traces?

I'm not sure.

For microwave boards, transmission can be laid out how?

I'm not sure.

What does not remain after etching?

I'm not sure.


The cloth or fiber material used, resin material, and the cloth to resin ratio determine the laminate's type designation (FR-4, CEM-1, G-10, etc.) and therefore the characteristics of the laminate produced. Important characteristics are the level to which the laminate is fire retardant, the dielectric constant (er), the loss factor (tδ), the tensile strength, the shear strength, the glass transition temperature (Tg), and the Z-axis expansion coefficient (how much the thickness changes with temperature).

What element of a laminate is designated by the cloth to resin ratio, among other things?

type designation

What's the name for the measurement of a laminate's change in thickness as its temperature changes?

Z-axis expansion coefficient

What's the abbreviation for the glass transition temperature of a laminate?

Tg

What determine's the silver's type designation?

I'm not sure.

What is not considered an important characteristic?

I'm not sure.

The Z-axis expansion coagulant is what?

I'm not sure.

The gain factor is one of the important what?

I'm not sure.

The shear sector is one of the important what?

I'm not sure.


There are quite a few different dielectrics that can be chosen to provide different insulating values depending on the requirements of the circuit. Some of these dielectrics are polytetrafluoroethylene (Teflon), FR-4, FR-1, CEM-1 or CEM-3. Well known pre-preg materials used in the PCB industry are FR-2 (phenolic cotton paper), FR-3 (cotton paper and epoxy), FR-4 (woven glass and epoxy), FR-5 (woven glass and epoxy), FR-6 (matte glass and polyester), G-10 (woven glass and epoxy), CEM-1 (cotton paper and epoxy), CEM-2 (cotton paper and epoxy), CEM-3 (non-woven glass and epoxy), CEM-4 (woven glass and epoxy), CEM-5 (woven glass and polyester). Thermal expansion is an important consideration especially with ball grid array (BGA) and naked die technologies, and glass fiber offers the best dimensional stability.

What's the common name of polytetrafluoroethylene?

Teflon

What pre-preg material is designated by "FR-2"?

phenolic cotton paper

To what type of packaging is thermal expansion particularly critical?

ball grid array

What material delivers optimum dimensional stability?

glass fiber

What dielectric is matte glass and polyester?

Thermal closure is an important what?

I'm not sure.

There is only one dielectric that can be chosen to do what?

I'm not sure.

FR-A is one of the what?

I'm not sure.

The ball gasket array (BGA) is an important what?

I'm not sure.


The reinforcement type defines two major classes of materials - woven and non-woven. Woven reinforcements are cheaper, but the high dielectric constant of glass may not be favorable for many higher-frequency applications. The spatially nonhomogeneous structure also introduces local variations in electrical parameters, due to different resin/glass ratio at different areas of the weave pattern. Nonwoven reinforcements, or materials with low or no reinforcement, are more expensive but more suitable for some RF/analog applications.

Along with the non-woven class, what makes up the reinforcement type materials?

woven

Which is the more expensive reinforcement type?

non-woven

What type of structure do woven reinforcements have that cause them to have variation in their electrical parameters?

spatially nonhomogeneous

Which ratio varies because of the structure of woven reinforcements?

resin/glass

For what kind of applications are non-woven reinforcement materials better than woven ones?

RF/analog

The reinforcement type defines which two minor classes of materials?

I'm not sure.

What is less expensive but more suitable for some RF/analog application?

I'm not sure.

Materials with low or no refinement are called what?

I'm not sure.

The high diode constant of glass may not be favorable for what?

I'm not sure.


At the glass transition temperature the resin in the composite softens and significantly increases thermal expansion; exceeding Tg then exerts mechanical overload on the board components - e.g. the joints and the vias. Below Tg the thermal expansion of the resin roughly matches copper and glass, above it gets significantly higher. As the reinforcement and copper confine the board along the plane, virtually all volume expansion projects to the thickness and stresses the plated-through holes. Repeated soldering or other exposition to higher temperatures can cause failure of the plating, especially with thicker boards; thick boards therefore require high Tg matrix.

What's the temperature at which resin softens and expands called?

glass transition temperature

Along with vias, what makes up the components of a board?

joints

What will happen to the components when the temperature of resin goes above that of glass transition?

mechanical overload

When resin stays below Tg, its thermal expansion is similar to that of copper and what other material?

glass

What do thick boards require to resist plating failure?

high Tg matrix

The resin in the composite hardens when?

I'm not sure.

Virtually no volume expansion projects to where?

I'm not sure.

Thin boards require high what?

I'm not sure.

Exposition to lower temperatures can cause failure of what?

I'm not sure.


Moisture absorption occurs when the material is exposed to high humidity or water. Both the resin and the reinforcement may absorb water; water may be also soaked by capillary forces through voids in the materials and along the reinforcement. Epoxies of the FR-4 materials aren't too susceptible, with absorption of only 0.15%. Teflon has very low absorption of 0.01%. Polyimides and cyanate esters, on the other side, suffer from high water absorption. Absorbed water can lead to significant degradation of key parameters; it impairs tracking resistance, breakdown voltage, and dielectric parameters. Relative dielectric constant of water is about 73, compared to about 4 for common circuitboard materials. Absorbed moisture can also vaporize on heating and cause cracking and delamination, the same effect responsible for "popcorning" damage on wet packaging of electronic parts. Careful baking of the substrates may be required.

What will happen to the materials when a board gets wet or is in a humid area?

Moisture absorption

If materials absorb moisture and then are heated enough to vaporize the water, the board might show delamination or what other type of damage?

cracking

What percentage absorption do F-4 epoxies have?

What's the approximate relative dielectric constant of most materials in circuit boards?

What material has an absorption rate of only 0.01%?

Teflon

What may also repel water?

I'm not sure.

Teflon has a high absorption rate of what?

I'm not sure.

What suffers from low water absorption?

I'm not sure.

Repelled water can lead to what?

I'm not sure.

Careful barking of the substrates may be what?

I'm not sure.


The printed circuit board industry defines heavy copper as layers exceeding three ounces of copper, or approximately 0.0042 inches (4.2 mils, 105 μm) thick. PCB designers and fabricators often use heavy copper when design and manufacturing circuit boards in order to increase current-carrying capacity as well as resistance to thermal strains. Heavy copper plated vias transfer heat to external heat sinks. IPC 2152 is a standard for determining current-carrying capacity of printed circuit board traces.

What's the minimum amount of copper a layer in a PCB can have to be considered "heavy copper"?

three ounces

About how thick would a PCB layer be if it contained three oz. of copper?

0.0042 inches

What will a circuit board with heavy copper carry very well?

current

What would a PCB designer use heavy copper to make their circuit board resist?

thermal strains

Where does the heat go when it leaves heavy copper-plated vias?

external heat sinks

The printed circuit board industry defines light copper as what?

I'm not sure.

PCB designers and fabricators often use light copper when?

I'm not sure.

What is the standard for determining current-carrying capacity of printed circuit board trees?

I'm not sure.

IAC 2152 is the standard for what?

I'm not sure.


Since it was quite easy to stack interconnections (wires) inside the embedding matrix, the approach allowed designers to forget completely about the routing of wires (usually a time-consuming operation of PCB design): Anywhere the designer needs a connection, the machine will draw a wire in straight line from one location/pin to another. This led to very short design times (no complex algorithms to use even for high density designs) as well as reduced crosstalk (which is worse when wires run parallel to each other—which almost never happens in Multiwire), though the cost is too high to compete with cheaper PCB technologies when large quantities are needed.

What arduous aspect of the process can designers skip in Multiwire?

routing of wires

What does the machine create by drawing a straight line between two points on the board?

a connection

Along with quick design times, what problem does Multiwire cut down on?

crosstalk

What makes Multiwire impractical to use when large quantities of a board are needed?

cost

In simple language, what are the interconnections in an embedding matrix?

wires

It was difficult to stack interconnections inside of what?

I'm not sure.

The machine will draw a wire in a curved line from one location/ to where?

I'm not sure.

What led to long design times?

I'm not sure.

What led to increased crosstalk?

I'm not sure.


Cordwood construction can save significant space and was often used with wire-ended components in applications where space was at a premium (such as missile guidance and telemetry systems) and in high-speed computers, where short traces were important. In cordwood construction, axial-leaded components were mounted between two parallel planes. The components were either soldered together with jumper wire, or they were connected to other components by thin nickel ribbon welded at right angles onto the component leads. To avoid shorting together different interconnection layers, thin insulating cards were placed between them. Perforations or holes in the cards allowed component leads to project through to the next interconnection layer. One disadvantage of this system was that special nickel-leaded components had to be used to allow the interconnecting welds to be made. Differential thermal expansion of the component could put pressure on the leads of the components and the PCB traces and cause physical damage (as was seen in several modules on the Apollo program). Additionally, components located in the interior are difficult to replace. Some versions of cordwood construction used soldered single-sided PCBs as the interconnection method (as pictured), allowing the use of normal-leaded components.

What type of construction is best for applications that need to portion space carefully?

Cordwood

What gets mounted in the middle of two parallel planes in a cordwood construction?

axial-leaded components

What do insulating cards prevent between interconnection layers?

shorting

What type of component has to be used in cordwood construction to its detriment?

nickel-leaded

What force caused the physical damage to components that affected the Apollo program?

Differential thermal expansion

What does not save significant space?

I'm not sure.

What was not soldered together?

I'm not sure.

What was one advantage of this system?

I'm not sure.

Components located on the exterior are what?

I'm not sure.


Development of the methods used in modern printed circuit boards started early in the 20th century. In 1903, a German inventor, Albert Hanson, described flat foil conductors laminated to an insulating board, in multiple layers. Thomas Edison experimented with chemical methods of plating conductors onto linen paper in 1904. Arthur Berry in 1913 patented a print-and-etch method in Britain, and in the United States Max Schoop obtained a patent to flame-spray metal onto a board through a patterned mask. Charles Ducas in 1927 patented a method of electroplating circuit patterns.

Who was the German inventor who wrote in 1903 about conductors being laminated in layers to a board?

Albert Hanson

What material did Thomas Edison experiment with by trying to chemically attach conductors to it?

linen paper

What year did Arthur Berry patent his print-and-etch method?

In Max Schoop's method, what was used to create the flame-sprayed pattern on the board?

a patterned mask

Who obtained a patent in 1927 for his method of electroplating circuit patterns?

Charles Ducas

development of the methods used in ancient printed circuit boards started when?

I'm not sure.

Albert Hanson described what in 1913?

I'm not sure.

Arthur Berry patented what in 1923?

I'm not sure.

Thomas Edison patented a print-and-etch method in what year?

I'm not sure.

In Germany Max Schoop obtained a patent to do what?

I'm not sure.


The Austrian engineer Paul Eisler invented the printed circuit as part of a radio set while working in England around 1936. Around 1943 the USA began to use the technology on a large scale to make proximity fuses for use in World War II. After the war, in 1948, the USA released the invention for commercial use. Printed circuits did not become commonplace in consumer electronics until the mid-1950s, after the Auto-Sembly process was developed by the United States Army. At around the same time in Britain work along similar lines was carried out by Geoffrey Dummer, then at the RRDE.

What was Paul Eisler making when he came up with the printed circuit?

a radio set

What event prompted the United States to adopt the printed circuit to make proximity fuses?

World War II

When was the printed circuit released for commercial use in the U.S.?

Who was working on the same type of large-scale application of printed circuits as the U.S. in Britain in the mid-1950s?

Geoffrey Dummer

What process was created by the U.S. Army that led to innovation in consumer electronics?

Auto-Sembly

The German engineer Paul Eisler invented what?

I'm not sure.

Paul Eisler invented the printed circuit in Germany in what year?

I'm not sure.

England began using the technology on a large scale in what year?

I'm not sure.

In 1958, the USA released the invention for what?

I'm not sure.

The Auto-Sembly process was developed by England in what year?

I'm not sure.


During World War II, the development of the anti-aircraft proximity fuse required an electronic circuit that could withstand being fired from a gun, and could be produced in quantity. The Centralab Division of Globe Union submitted a proposal which met the requirements: a ceramic plate would be screenprinted with metallic paint for conductors and carbon material for resistors, with ceramic disc capacitors and subminiature vacuum tubes soldered in place. The technique proved viable, and the resulting patent on the process, which was classified by the U.S. Army, was assigned to Globe Union. It was not until 1984 that the Institute of Electrical and Electronics Engineers (IEEE) awarded Mr. Harry W. Rubinstein, the former head of Globe Union's Centralab Division, its coveted Cledo Brunetti Award for early key contributions to the development of printed components and conductors on a common insulating substrate. As well, Mr. Rubinstein was honored in 1984 by his alma mater, the University of Wisconsin-Madison, for his innovations in the technology of printed electronic circuits and the fabrication of capacitors.

What company developed the first electronic circuit that could be mass produced and was durable enough to be fired from a gun?

Globe Union

What was the plate used for anti-aircraft proximity fuses in World War II made out of?

ceramic

Who was in charge of the Centralab Division of Globe Union when the PCB used in anti-aircraft fuses was invented?

Harry W. Rubinstein

What award did Rubinstein win in 1984 for his contributions?

Cledo Brunetti Award

Where did Harry Rubinstein attend college?

University of Wisconsin-Madison

During World War I, the development of the anti-aircraft proximity fuse required what?

I'm not sure.

In 1994, the IEEE awarded whom the Cledo Brunetti Award?

I'm not sure.

Ms. Harriet W. Rubenstein was the former head of which division?

I'm not sure.

Mr. Rubenstein was honored in 1994 by which university?

I'm not sure.


Originally, every electronic component had wire leads, and the PCB had holes drilled for each wire of each component. The components' leads were then passed through the holes and soldered to the PCB trace. This method of assembly is called through-hole construction. In 1949, Moe Abramson and Stanislaus F. Danko of the United States Army Signal Corps developed the Auto-Sembly process in which component leads were inserted into a copper foil interconnection pattern and dip soldered. The patent they obtained in 1956 was assigned to the U.S. Army. With the development of board lamination and etching techniques, this concept evolved into the standard printed circuit board fabrication process in use today. Soldering could be done automatically by passing the board over a ripple, or wave, of molten solder in a wave-soldering machine. However, the wires and holes are wasteful since drilling holes is expensive and the protruding wires are merely cut off.

What type of construction was originally used for all electronic components?

through-hole

In what year was the Auto-Sembly process created?

Although two men developed the Auto-Sembly process, to whom was the patent officially granted?

U.S. Army

What year was the patent for the Auto-Sembly process granted?

Which part of the Auto-Sembly manufacturing process is the most costly?

drilling holes

Originally, no electronic component had what?

I'm not sure.

Who developed the Auto-State process in which component leads were inserted into a copper foil?

I'm not sure.

Soldering could be done manually by passing the board over a ripple, or wave, of molten silver in what?

I'm not sure.

What is considered not wasteful?

I'm not sure.


Greek colonies and communities have been historically established on the shores of the Mediterranean Sea and Black Sea, but the Greek people have always been centered around the Aegean and Ionian seas, where the Greek language has been spoken since the Bronze Age. Until the early 20th century, Greeks were distributed between the Greek peninsula, the western coast of Asia Minor, the Black Sea coast, Cappadocia in central Anatolia, Egypt, the Balkans, Cyprus, and Constantinople. Many of these regions coincided to a large extent with the borders of the Byzantine Empire of the late 11th century and the Eastern Mediterranean areas of ancient Greek colonization. The cultural centers of the Greeks have included Athens, Thessalonica, Alexandria, Smyrna, and Constantinople at various periods.

Where are Greek States believed to have been settled ?

Greek colonies and communities have been historically established on the shores of the Mediterranean Sea and Black Sea

Which two bodies of water are believed to be central to the establishment of the Greek society ?

Greek people have always been centered around the Aegean and Ionian seas

When was the emergence of the Greek spoken dialect believed to have started ?

the Greek language has been spoken since the Bronze Age.

Where have the centers of culture been located for the Grecian world historically ?

The cultural centers of the Greeks have included Athens, Thessalonica, Alexandria, Smyrna, and Constantinople at various periods.

What other culture did the Greek states share boarders with ?

these regions coincided to a large extent with the borders of the Byzantine Empire of the late 11th century

Where have Egyptian colonies been historically established?

I'm not sure.

What two seas have the Egyptian people always lived close to?

I'm not sure.

How long has the Egyptian language been spoken?

I'm not sure.

In what century was the Egyptian empire prominent?

I'm not sure.

What are two cities associated with the formation of Egyptian culture?

I'm not sure.

Which two seas have been least central to Greek history?

I'm not sure.

During which prehistoric age was the Latin language invented?

I'm not sure.

Which city in modern Turkey was once a minor center of Greek culture?

I'm not sure.

What tenth century empire had roughly the same extent as ancient Greece's?

I'm not sure.

Which area of South Africa has hosted Greek communities in the past?

I'm not sure.

Which two seas have been least central to Greek history?

I'm not sure.

During which prehistoric age was the Greek language rejected?

I'm not sure.

Which city in modern Iran was once a major center of Greek culture?

I'm not sure.

Which area of North Africa has hosted Irish communities in the past?

I'm not sure.

What twelfth century empire had roughly the same extent as ancient Greece's?

I'm not sure.