Comprehensive guide to PCB design and manufacturing terminology.
The area of copper pad remaining after a hole is drilled. Minimum annular ring affects manufacturing yield.
Automated Optical Inspection. Camera-based quality check for solder joints and components.
The ratio of board thickness to drilled hole diameter. Higher ratios are more challenging to manufacture.
Ball Grid Array. A surface mount package with solder balls arranged in a grid pattern on the bottom.
A via that connects an outer layer to one or more inner layers but doesn't go through the entire board.
Bill of Materials. A list of all components required for PCB assembly.
A via that connects inner layers only and is not visible from either surface of the board.
Computer Aided Manufacturing. Software used to prepare design files for PCB fabrication.
Half-holes at board edges used for edge-mounting modules or as test points.
The minimum distance between conductive elements (traces, pads, copper pours).
Protective coating applied to assembled PCB for moisture and contamination protection.
Traces designed to have a specific impedance value, critical for high-speed signals.
Large area of copper fill, typically connected to ground or power, also called copper plane.
Thickness of copper foil, measured in oz/ft². 1 oz = 35 μm = 1.378 mil.
A rigid laminate with copper on one or both sides, forming the base of a multilayer PCB.
The shortest distance along a surface between two conductors. Important for high voltage designs.
Unwanted coupling of signals between adjacent traces.
Design for Assembly. Design practices that optimize PCB assembly process.
Design for Manufacturing. Design practices that ensure the PCB can be reliably manufactured.
Non-conductive material between copper layers, typically FR4 or high-frequency laminates.
Two traces carrying opposite polarity signals, used for high-speed data transmission.
Design Rule Check. Automated verification that design meets manufacturing constraints.
A single drilling operation on the PCB. Total drill hits affect manufacturing time and cost.
Electroless Nickel Immersion Gold. A surface finish with nickel barrier and thin gold layer.
Reference marks on PCB for automated pick-and-place machine alignment.
Test method using moving probes to check electrical connectivity without fixed fixtures.
Flame Retardant 4. The most common PCB substrate material, glass-reinforced epoxy.
Standard file format for PCB fabrication data, defining copper layers, soldermask, etc.
Hot Air Solder Leveling. Surface finish process using molten solder and hot air.
In-Circuit Test. Electrical test using bed-of-nails fixture to verify component values.
Total opposition to current flow in AC circuits, measured in ohms. Critical for signal integrity.
Copper layers inside a multilayer PCB, not visible from the outside.
The base material of PCB consisting of resin and reinforcement (typically glass fiber).
A trace on outer layer with reference plane below, common for controlled impedance.
Non-Plated Through Hole. A hole without copper plating, used for mounting.
Organic Solderability Preservative. Water-based organic surface finish.
A copper area designed for component lead attachment, either for SMD or through-hole.
Automated machine that places SMD components on PCB before reflow soldering.
Pre-impregnated fiberglass with uncured resin, used to bond core layers in multilayer PCBs.
Plated Through Hole. A hole with copper plating connecting layers.
Soldering process where solder paste is melted in an oven to attach SMD components.
The path current takes to return to source, ideally directly beneath the signal trace.
The quality of an electrical signal, affected by impedance, crosstalk, and reflections.
Layer of ink on PCB showing component designators, logos, and other markings.
Time difference between signals that should arrive simultaneously, critical in differential pairs.
Mixture of tiny solder particles and flux, applied to pads before component placement.
Protective layer covering copper except where soldering is needed, typically green.
The arrangement of copper and dielectric layers in a multilayer PCB.
Thin metal sheet with apertures used to apply solder paste to PCB pads.
A trace on inner layer between two reference planes, providing better shielding.
Coating applied to exposed copper to prevent oxidation and ensure solderability.
Gradual widening where trace meets pad, improving reliability at connection point.
A pattern connecting a pad to a copper pour that aids soldering by limiting heat dissipation.
A pathway of copper connecting components, also called track or conductor.
A plated hole connecting copper on different layers of a PCB.
A via placed within a component pad, often filled and plated over for BGAs.
Process where PCB passes over a wave of molten solder for through-hole components.
Non-destructive testing to inspect solder joints under BGA and other hidden areas.