PCB Glossary


FR4 is a sign for rating flame resistant material. It specifies that resin material is capable of automatically extinguishing when it is in a flame state.


Substrate, laminate is the base material for PCB fabrication.

Copper Foil

Copper foil is base copper provided in sheet form or clad.

Gerber File

Data file used to control a photoplotter.

Line width

Line width means the width the conductors / trace on the board.

Line space

Line space means the distance between two adjacent conductors/ traces on a board.

External layer

External layer of PCB, also called outer layer, is an outer copper layer where components are attached to.

Internal layer

Internal layer refers to inner layers in multi-layer PCBs, mostly signal layers.

Silk screen

Silk screen (legend or overlay) is designed for placing component names and positions to ease the assembly.

Solder Mask

Solder Mask (Solder resist) is a coating applied to a circuit board to prevent solder to deposit on.

Carbon mask

Carbon mask is a type of liquid heat curing conductive carbon paste that is added to pad surface.

Solder bridge

Solder bridge is solder connect two or more adjacent pads to form a conductive path.

Peelable solder mask

Peelable solder mask is a layer of solder mask that can be peeled from the board.

Annular ring

Annular ring is a copper ring that connects to thru-hole wall and flat attached to the board.


PTH (plated-through hole) is a plated hole used as a conducting interconnection.


NPTH is non-plated through-hole.

Annular Ring

The width of the conductor pad surrounding a drilled hole.


Cutout refers to a groove that is dug on a PCB.


Microvias are holes or vias with size vary small and need laser-created .

Tented via

Tented via is a via with dry film solder mask completely covering both its pad and plated-thru hole.

Blind via

Blind via is a conductive surface hole that connects an outer layer with an inner layer of a multi-layer PCB board.

Buried via

Buried via is a via hole that does not extend to the surface of circuit boards.

Press fit holes

Press fit holes are holes through which a contact terminal can be pressed into a circuit board.

Castellated holes

Castellated holes half cut holes refer to holes that are drilled but was cut half at the edge with copper on hole wall.

Via in pad

Via in pad is thru hole on the pad which is a significant composition in multi-layer PCB.


HDI, a short form for high density interconnector, is a type of technology for PCB fabrication. It depends on micro blind via technology to manufacture PCBs with traces organized with high density.


BGA is ball grid array, a type of component package form applied in integrated circuit for surface mounting.

Via filled with resin

Via filled with resin or via filled with resin is a through hole with no dent on the surface so that soldering won’t be influenced.

Hole breakout

Hole breakout means a hole is partially surrounded by the land.


Fiducial is an etched feature or drilled hole used for optical alignment during assembly operations.

Fine pitch

Fine pitch is commonly referred to surface-mount components with micro spacing between leads.


SMOBC (Solder Mask Over Bare Copper) is a method of fabricating circuit board that results in final metallization being copper with no protective metal.

Surface finish

Surface finish is a protection layer to be attached to copper foil to avoid PCB board oxidized.

Gold fingers

Gold fingers are connectors on the edge of a PCB after gold plating. They have to be hard, smooth, and flat, behave excellently as a conductor


Chamfer is a corner that has been rounded to eliminate an otherwise sharp edge.


Bevel is an angled edge of a printed circuit board usually for gold fingers .

Edge connector

Edge connector is a connector on the PCB substrate edge as either plated pads or lines of coated holes used to connect other circuit boards or electronic device.

Test Coupon

Test Coupon is a sample normally made outside the actual board pattern that is used for testing to verify certain quality parameters without destroying the actual board.


Pressing means the process by which a combination of heat and pressure are applied to a book, thereby producing fully cured laminated sheets.

Back drilling

Back drilling mainly applied in multilayer PCB manufacturing to ensure signal integrity through drilling off stub between layers with no via from the back.

Pattern plating

Pattern plating means the selective plating of a conductive pattern.


Etching is chemical removal of copper to get a desired circuit pattern.


V-scoring, V-cut is incomplete cut off in a PCB usually for ease to separate PCB panel.


Panelize or penalization is a method of PCB manufacturing through combining different boards into one panel to increase the manufacturing efficiency.


RF means radio frequency, identifies electromagnetic frequency that can be radiated to the space with a frequency ranging from 300 KHz to 300GHz.


Woven glass materials exceptionally well controlled electrical and mechanical properties. The dielectric constant range is 2.45 to 2.65 used for RF applications.

Chip-on-board (COB)

Chip on board is a type of bare chip SMT technology by directly mounting chip on a PCB.


Backplane refers to the supporting plane in circuit board, which plays a role of insulation.

Metal core PCB

Metal core PCB, metal base PCB or MC PCB refers to the board whose core material is metal, such as aluminum or copper.

Flex circuit

Flex circuit also FPC is circuit board made of thin and flexible material.

Rigidflex PCB

Rigidflex PCB or rigid-flex PCB is a kind of construction combining flexible PCB and rigid PCB.

PCB house

PCB house is the factory fabricates PCB.


Schematic is created as the first step of a PCB design. It includes graphic symbols of the electrical connections and functions of the circuit board.

CAM Files

CAM files are the files provide the information for printed circuit board manufacturing.


CAD, Computer Aided Design, refers to the software used by a PCB designer to create the data for manufacture and assemble circuit board and components.


CAM, Computer Aided Manufacturing, refers to the software used by PCB manufacturers’ engineer to prepare engineering files for PCB manufacturing process.

PCB Assembly

PCB Assembly refers to a series of procedures after are placed and fixed on PCB in order to implement electrical functions.

Active components

Active components refer to components acquired or depending on current flow direction including transistor, silicon controlled rectifier, valve etc.

PCB Assembly drawing

PCB Assembly drawing is a reference describing assembly requirements based on which assembly technologies, method, parameters etc. are defined.

PCB Assembly house

PCB Assembly house is a place that assembly PCBs and components.