PCB design glossary

Autorouter

An EDA tool that lays down copper traces on a PCB automatically, based on the schematic netlist and a set of design rules.

BOM

Bill of Materials — the parts list for a PCB, ready for ordering and assembly.

Copper Layer

A conductive layer of a PCB — where traces, pads, planes, and vias live.

Courtyard

The keepout area around a component footprint — reserves space for the body and adjacent components.

CPL

Component Placement List — the X/Y positions and rotations of every part on a PCB, used by pick-and-place machines.

Design Rules

The set of physical constraints a PCB layout must respect — trace width, clearance, via size, drill diameter, courtyard.

Differential Pair

Two traces routed together that carry equal-and-opposite signals — used for high-speed differential signaling.

DRC

Design Rule Check — automated verification that a PCB layout respects manufacturing tolerances.

Drill File

A file (usually Excellon format) that tells the fab where to drill holes — for vias and through-hole pads.

ERC

Electrical Rule Check — automated verification of a schematic for connectivity and pin-usage errors.

Fab Profile

A named set of design rules matched to a specific PCB fabricator's tolerances (e.g. JLCPCB Standard).

Footprint

The land pattern (pads, courtyard, silkscreen) on a PCB that physically holds a component.

Gerber

The de-facto file format used to send PCB layer artwork to a fab house.

Ground Plane

A large copper area on a PCB layer dedicated to the ground net — improves return paths and EMI.

Net

A single electrical connection in a schematic — every pin on the same net is electrically tied together.

Netlist

The list of every electrical connection (net) in a circuit, derived from the schematic.

Pad

An exposed copper area on a PCB that a component lead solders to.

PCB

Printed Circuit Board — the physical board that holds components and routes signals between them.

Schematic

The symbolic drawing of a circuit, showing components and how they connect electrically.

Silkscreen

The white (or other-color) ink layer on a PCB used for labels, reference designators, and component outlines.

Soldermask

The (usually green) polymer coating on a PCB that protects copper and exposes only the pads.

Stack-up

The arrangement of copper, prepreg, and core layers in a PCB, from top to bottom.

Test Point

An exposed pad placed on a PCB specifically so a probe can attach to it during bring-up or production test.

Trace

A copper line on a PCB that carries a signal between two or more pads.

Via

A plated hole that electrically connects a net between two or more layers of a PCB.