PCB Glossary

The ring of copper around a drilled hole that connects it to a trace or pad.

Automated Optical Inspection — a vision system that checks component placement on a PCBA after the reflow oven.

Quality management standard for the aerospace industry. Required for most aerospace and defense work.

Approved Vendor List — the list of pre-qualified suppliers a company is allowed to buy from.

Bill of Materials — the list of every component needed to assemble a board, with part numbers, manufacturers, and quantities.

Full system integration: putting a PCBA into an enclosure with cables, displays, fans, and other parts to create a finished product.

A protective spray applied to a finished PCBA to shield it from moisture, dust, and chemicals.

A trace designed to a specific impedance value (often 50Ω) to maintain signal integrity at high speeds.

Component Placement List (or Pick-and-Place file) — tells the assembly robot the X-Y coordinates and rotation of every component.

Design for Manufacturability — checking a design against fabrication capabilities to avoid yield issues.

Electronic Manufacturing Services — companies that assemble PCBAs (and often full products) for OEMs. Also called contract manufacturers (CMs).

Electroless Nickel Immersion Gold — a flat, gold-colored surface finish ideal for fine-pitch components.

First Article Inspection — a documented inspection of the first unit produced, used to qualify a new supplier or revision.

Flame Retardant 4 — the standard glass-reinforced epoxy laminate used as a PCB substrate. The default for ~90% of rigid boards.

The standard 2D file format used to describe each layer of a PCB to the fabricator.

Gold-plated stripes along the edge of a PCB used for plugging into a slot connector (e.g. RAM modules).

Hot Air Solder Leveling — an inexpensive surface finish that coats copper pads with solder. Available in tin-lead and lead-free.

High Density Interconnect — boards with very fine traces, microvias, and stacked vias. Found in smartphones and advanced wearables.

Quality management standard for the automotive industry.

In-Circuit Test — an electrical test of a populated board using a bed-of-nails fixture to verify each component.

The trade association whose standards define PCB acceptability (IPC-A-600 for bare boards, IPC-A-610 for assemblies) and reliability classes 1–3.

Dedicated service electronics — most industrial and consumer products. The most common quality class.

High-reliability electronics — medical, aerospace, military. Strictest IPC requirements.

Quality management standard for medical device manufacturing.

General quality management system certification. Table-stakes for most B2B suppliers.

International Traffic in Arms Regulations — U.S. export controls on defense-related items. Required for many DoD programs.

Metal-Core PCB — uses an aluminum or copper base instead of FR-4 to pull heat away from components. Dominant in LED lighting.

A B2B sales qualification framework: Metrics, Economic buyer, Decision criteria, Decision process, Paper process, Identify pain, Champion, Competition.

A very small laser-drilled via, typically used in HDI boards to connect adjacent layers.

Non-Conformance Report — documentation of a defect or deviation, used to track supplier quality issues.

New Product Introduction — the phase between prototype and full production where a design is being ramped up.

Non-Recurring Engineering — one-time setup costs for a new program (tooling, stencils, test fixtures, FAI).

Original Equipment Manufacturer — the brand that designs and sells the end product (Apple, Tesla, Medtronic, etc.).

Organic Solderability Preservative — a cheap, environmentally friendly surface finish with a shorter shelf life.

The larger sheet of material that multiple individual PCBs are fabricated on simultaneously.

Printed Circuit Board Assembly — a PCB with all components soldered on. Sometimes called a 'loaded,' 'stuffed,' or 'populated' board.

The robot in an SMT line that places thousands of components per hour onto solder paste on a board.

Pre-impregnated glass fabric used to bond layers together in a multilayer PCB. It melts and cures during lamination.

Plated Through-Hole — a hole drilled through a board and plated with copper to connect layers or accept a component lead.

An oven that heats a populated board through a controlled temperature profile, melting solder paste to bond components.

Request for Quote — a customer's formal request for pricing on a specific board and quantity.

A brand of low-loss laminate materials commonly used for high-frequency and RF PCBs.

Restriction of Hazardous Substances — a European directive requiring lead-free electronics. Widely adopted globally.

The printed (usually white) layer that labels components, polarities, and reference designators on a PCB.

Surface-Mount Technology — assembly method where components sit flat on the board surface instead of through holes.

The protective coating (usually green) applied over copper to prevent shorts and oxidation.

The arrangement of copper and dielectric layers that make up a multilayer PCB.

The insulating base material of a PCB (typically FR-4) that copper traces sit on.

A copper line on a PCB that carries electrical current between two points.

Underwriters Laboratories — a safety certification often required for PCBs sold in North America.

A plated hole that connects copper on different layers of a PCB. Types include through-hole, blind, and buried.