Monday, March 16, 2009

PCB Glossary : S to Z

A technique in which grooves are machined on opposite sides of a panel to a depth that permits individual boards to be separated from the panel after component assembly.

Screen Printing:
A process for transferring an image to a surface by forcing suitable media through a stencil screen with a squeegee.

Single-Sided Board:
A printed board with conductive pattern on one side only.

Soldermask Over Bare Copper (SMOBC):
A method of fabricating a printed circuit board that results in final metallization being copper with no protective metal. The non-coated areas are coated by solder resist, exposing only the component terminal areas. This eliminates tin lead under the pads.

Surface Mount Technology (SMT):
Defines the entire body of processes and components that create printed circuit board assemblies with leadless components.

An alloy that melts at relatively low temperatures and is used to join or seal metals with higher melting points. A metal alloy with a melting temperature below 427°C (800°F).

Coating material used to mask or to protect selected areas of a pattern from the action of an etchant, solder, or plating. Also called resist or mask.

A method by which successive exposures to a single image are made to produce a multiple image production master.

The process by which imaging material (resist) is chemically removed from a panel during fabrication.

A material on whose surface adhesive substance is spread for bonding or coating. Also, any material that provides a supporting surface for other materials used to support printed circuit patterns.

Test Coupon:
A portion of a printed board or of a panel containing printed coupons used to determine the acceptability of such a board.

Glass transition temperature. The point at which rising temperatures cause the solid base laminate to start to exhibit soft, plastic-like symptoms. This is expressed in degrees Celsius (°C).

Tooling Holes:
The general term for holes placed on a PCB or a panel of PCBs for registration and hold-down purposes during the manufacturing process.

Top Side:
See Component Side.

A common term for conductor.

The list of instructions describing the board, including any specific processing requirements. Also called a shop traveler, routing sheet, job order, or production order.

A laminate defect in which deviation from planarity results in a twisted arc.

Underwriters Laboratories, Inc., an independent product safety testing and certification organization.

Underwriters Symbol:
A logotype denoting that a product has been recognized (accepted) by Underwriters Laboratories Inc. (UL).

A plated through-hole that is used as an interlayer connection but does not have component lead or other reinforcing material inserted in it.

The absence of any substances in a localized area.

Wave Soldering:
A process wherein assembled printed boards are brought in contact with a continuously flowing and circulating mass of solder, typically in a bath.

X Axis:
The horizontal or left-to-right direction in a two dimensional system or coordinates.

Y Axis:
The verticle or bottom-to-top direction in a two dimensional system of coordinates.

Z Axis:
Perpendicular to the plane formed by the X and the Y datum reference.

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