circuit card definition of circuit card in the Free Online Encyclopedia.

printed circuit board

A rigid, flat board that holds chips and other electronic components. The board is made of layers, typically two to 10, that interconnect components via copper pathways. The main printed circuit board (PCB) in a system is called a "system board" or "motherboard," while smaller ones that plug into the slots in the main board are called "boards" or "cards." See flexible circuit.

Etched Circuits
The "printed" circuit is an etched circuit. A copper foil is placed over a fiberglass or plastic base of each layer and covered with a photoresist. Light is beamed through a negative image of the circuit paths onto the photoresist, hardening the areas that will remain after etching. When passed through an acid bath, the unhardened areas are washed away. The finished layers are then glued together. A similar process creates the microminiaturized circuits on a chip (see chip).

Starting in the 1940s
Printed circuits were first used in the 1940s to connect discrete components together. By the 1960s, PCBs were widely used in all electronic systems, but still mostly connecting discrete components. Integrated circuits (chip) were emerging and added to the boards, and by the 1980s, PCBs were holding large quantities of chips. Today, printed circuit boards typically connect mostly chips with only a few discrete components, each chip containing from a few thousand up to hundreds of millions of transistors. See surface mount, via, discrete component, chip, card and motherboard.

Printed Circuit Boards

The motherboard is the primary printed circuit board in a computer. The drawing at the top shows a Baby AT style motherboard in a PC. The adapter cards plug into the expansion slots on the motherboard.

printed circuit board [′print·əd ′sər·kət ‚bȯrd]

(electronics)

A flat board whose front contains slots for integrated circuit chips and connections for a variety of electronic components, and whose back is printed with electrically conductive pathways between the components. Also known as circuit board.

(hardware)

printed circuit board - (PCB) A thin board to which electronic components are fixed by solder. Component leads and integrated circuit pins may pass through holes ("vias") in the board or they may be surface mounted, in which case no holes are required (though they may still be used to connect different layers).

The simplest kind of PCB has components and wires on one side and interconnections (the printed circuit) on the other. PCBs may have components mounted on both sides and may have many internal layers, allowing more connections to fit in the same board area. Boards with internal conductor layers usually have "plated-through holes" to improve the electrical connection to the internal layers.

The connections are metal strips (usually copper). The pattern of connections is often produced using photo-resist and acid etching. Boards, especially those for high frequency circuits such as modern microprocessors, usually have one or more "ground planes" and "power planes" which are large areas of copper for greater current carrying ability.

A computer or other electronic system might be built from several PCBs, e.g. processor, memory, graphics controller, disk controller etc. These boards might all plug into a motherboard or backplane or be connected by a ribbon cable.

Printed Circuit Board

a board whose surfaces have printed current conductors with contact areas, which are used to connect components mounted on the boards according to the circuit diagram of a functional subassembly for electric or radio apparatus, and also have plated circuit holes and nonplated mounting holes. There are about 200 methods for making printed circuit boards; among the most important are the photochemical, photoelectrochemical, and offset-electrochemical methods. The methods differ in the means of producing the conductive coating or the form in which the pattern of the printed conductors is realized.

The dimensions of printed circuit boards, the position of the hole centers, and the hole diameters are standardized. The boards are 10–360 mm long, 10–240 mm wide, and 0.05–3.0 mm thick (depending on the rigidity required). The spacing of the coordinate grid for marking the holes is 2.5 mm or, less frequently, 1.25 mm, and the hole diameters range from 0.2 to 3 mm. A distinction is made among one-sided, two-sided, and multilayer boards (up to 15 layers). Multilayer boards are made by using extended leads, by metallizing the walls of through holes, by molding two-sided boards in pairs, or by layer-by-layer buildup. The material most often used for printed circuit boards are metal-clad and plain Micarta and fiberglass laminates, reinforced fluorine plastic, polystyrene, polyethylene terephthalate, polyamide, polycarbonate, and radioceramics.

REFERENCE

Konstruirovanie i tekhnologiia pechatnykh plat. Moscow, 1973.

B. P. LIKHOVETSKII

Mentioned in	?		References in periodicals archive	?		Encyclopedia browser	?		Full browser	?
No references found			For the standard, China Unionpay issued its own chip card standards in 2005, namely, Chinese Financial Integrated Circuit Card Regulations (PBOC2. Research Report of Chinese Bank IC Card Industry, 2009 by Kate Chen / Banking, finance and accounting community If it becomes clogged with dirt, its circuit cards can overheat. It's the simple things! by PS, the Preventive Maintenance Monthly The trouble is solved, and the circuit card is returned to the manufacturer who built the final system, but typically not the manufacturer of the card. Does electronics really have a surface contamination problem? As ... by Munson, Terry / Circuits Assembly			circle of longitude circle of perpetual apparition circle of perpetual occultation Circle of Pious Zealots circle of position circle of probable error circle of right ascension circle of uncertainty circle of Willis circle shear circle sheet circle trowel circle-dot mode circle-on-circle face circle-on-circle sunk face Circleville circline lamp circling approach area circuit circuit analyzer circuit bending circuit board circuit breaker CIRcuit CALculus circuit capacity circuit card circuit cellular circuit conditioning circuit controller circuit design Circuit Diagram circuit efficiency circuit element circuit grade circuit interrupter circuit loading circuit main circuit noise circuit noise level circuit protection circuit reliability circuit rider circuit riding Circuit Session of a Court circuit shift circuit switch circuit switched Circuit Switching circuit testing circuit theory circuit trace			Circuit Board Design System Circuit Board Drill Circuit Board Extractor Circuit Board Functional Specification Circuit Board Jack Circuit Board Technology Circuit boards Circuit boards Circuit braker Circuit braker Circuit braker circuit breaker circuit breaker circuit breaker circuit breaker Circuit Breaker 1 Circuit Breaker A-C Only Circuit Breaker Box Circuit Breaker DC Only Circuit Breaker Manufacturer Circuit breaker panel Circuit breakers Circuit breakers Circuit breakers Circuit Bridging Location Termination Circuit Bundling Initiative Circuit busy CIRcuit CALculus CIRcuit CALculus circuit capacity circuit card Circuit Card Assembly Circuit Card Assembly and Materials Task Force Circuit Card Module Circuit Català de Cinema Digital circuit cellular Circuit City, Inc. Circuit Client Circuit Components Inc. Circuit Concentration Bay circuit conditioning Circuit Configuration Table Circuit Connection Table Circuit Consultants Ltd Circuit Control Office Circuit Control Officer circuit controller circuit court circuit court Circuit Court Case Reporter circuit court of appeals Circuit Court of Cook County Circuit Court of Customs and Patent Appeals Circuit Court Probation Department Circuit courts Circuit courts Circuit Creation on Demand

Printed Circuit Board (redirected from circuit card)

REFERENCE

Printed Circuit Board
(redirected from circuit card)