PCB Glossary : S to Z

Scoring:
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.

Solder:
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).

Soldermask:
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.

Step-and-Repeat:
A method by which successive exposures to a single image are made to produce a multiple image production master.

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

Substrate:
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.

TG:
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.

Trace:
A common term for conductor.

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

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

UL:
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).

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

Void:
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.