Printed Wiring Board Terms

Illustrated dictionary of electronics
"A" "B" "C", "D", "E", "F", "G", "H", "I", "J", "K", "L", "M",
"N", "O", "P", "Q", "R", "S", "T", "U", "V", "W", "X", "Y", "Z"

Editor note; All the PWB terms are listed below. The alphabetic links above will switch to the main general engineering dictionary, so scroll down the page for definitions related to Printed Wiring Boards.

'A' to 'Ge', 'Gr' to 'O', 'P' to 'R', 'S', 'T' to 'Z'

Packages: IC Package Acronyms. IC Packaging Dictionary

Pad: A portion of a conductive pattern used as a soldering area. Also called a land. The metallized area on a substrate or on the face of an integrated circuit used for making electrical connections. Pads are used to make the electrical connection between the via and the trace or plane shape on a given layer. For a via to make a solid connection to a trace on a PCB layer, a pad must be present for mechanical stability.

Panel: The size of the raw material used to fabricate one or more printed wiring boards [depending on the PWB size]. A Panel may hold one or more printed circuit boards [graphic in right side-bar].

PCB: Printed Circuit Board. A board designed to hold components via soldering. A PCB is the same as a Printed Wiring Board. The terms Printed Circuit Board and Printed Wiring Board are synonyms and are used interchangeable. A PCB or PWB become an Printed Circuit Card Assemble once parts are installed.

PCB Example
Printed Circuit Board

PCTF: Plated Copper on Thick films.

Permittivity: See Dielectric Constant.

Photo-Etching: Chemical process of removing unwanted material in producing printed circuit boards.

Photoimageable: Text in review --

Photoresist: A light sensitive material. A positive resist becomes soluble to the photoresist developer when exposed to light. While a negative resist becomes insoluble.

Pin Escape: A procedure in Printed Wiring Board routing [PWB] that allows the trace of an IC pin to be routed through or escape the pin field of the IC. Pin Escaping is a routing technique that routes the trace from the origination pin of an IC over to its destination or via. Also called Pin Break-Out. Small pitch BGAs represent the most difficult IC to pin escape.

Pitch: The nominal distance from center to center of adjacent conductors or leads.

Planes: An uninterrupted area of metal covering the entire PCB layer. A planelet, a variation of a plane, is an uninterrupted area of metal covering only a portion of a PCB layer. Typically, a number of planelets exist in one PCB layer. Planes and planelets distribute power to a number of points on a PCB, or used as a return path [ground].

Plated-Through-Hole: [PTH] A plated-through hole is one formed by a deposition of metal on the inside surface of a through-hole. Also known as a supported hole. The configuration is used to provide additional mechanical strength

Plated Through-hole, Via

to the soldered termination or to provide an electrical interconnection on a multilayer PWB. Also refer to Via.

Plating: metallic deposit on a surface, formed either chemically or electro-chemically.
MIL-T-10727C - Tin Plating: Electro-Deposited or Hot-Dipped, for Ferrous and Non-ferrous metals
MIL-C-14550B - Copper Plating, (Electro-Deposited)

Prepreg: Short for Pre-impregnated. A formulated resin matrix system, that is reinforced with man-made fibers such as carbon, glass and aramid. Normally a epoxy coated fiber-glass that is used to laminate two different core material layers together.

Printed Wiring Board: A pattern of conductors printed (screened) onto the surface of an insulating base to provide interconnection for parts.

Printed board part number: The term printed board part number refers to a printed circuit or wiring board of a single specific part number and classification for a printed board configuration. All samples of a printed board part number are to be electrically and functionally interchangeable with each other, have the same electrical and environmental test limits and use the same basic raw materials, and fabrication processes.

Propagation velocity: The time in which signals propagate over the board. As a rule of thumb this site uses 150ps/inch for FR4 [Board Material], and 130pS/inch for Polimide [Board Material]. The Propagation velocity varies with board material and layer the signal trace resides on. Also refer to data relating to PCB Material and Signal Velocity

PWB: Printed Wiring Board. See also PCB.

Reference Plane. Refers to one or more layers on a multi-layer printed wiring board which contains only one voltage, normally ground. A layer of copper that occupies an entire board layer, with the exception of any board keep-outs and unconnected vias which pass through the layer. Ground [zero voltage] is most often used as the reference plane, but any voltage used in the circuit may be used as the reference.

Rework: The act of repeating one or more manufacturing operations, or performing alternative techniques in order to bring a product into compliance with applicable drawings and specifications.

Rigid Flex PCB: A Printed Circuit Board [PCB] that is both rigid and flexible, see Rigid Flexible Laminate below.

Rigid Flexible Laminate: A flexible printed wiring board. A flexible printed wiring board in combination with a rigid printed wiring board. In the example to the right the center of the board uses flexible laminate while both ends of the PWB use rigid laminate construction.

Reference; MIL-STD-2118 - Flexible and Rigid-Flex Printed Wiring for Electronic Equipment Design Requirements.

RoHS: The Restriction of Hazardous Substances standard limits the amount of certain elements used in the manufacture of electronic components. There are six chemicals that are controlled under the standard. Detailed RoHS Description.

PC motherboard

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