Glossary of Terms

Active components

Active components refer to a type of components accquired or depending on current flow direction including transistor, silicon controlled rectifier, valve etc. Virtually, it can be regarded as components that are not resistor, capactior or inductor.

Annular ring

An annular ring refers to a copper ring that is connected to thru-hole wall and flat attached to the board. It is an important consideration in PCB design.

Anti solder ball

Anti solder ball is a technology applied in SMT production line, aiming to limit the amount of tin through stencil by making stencil from opening window at places where solder ball tends to be produced so that tin paste will flow to places where there's no tin paste.

Any layer inner via hole

Any layer inner via hole, short for ALIVH, is a type of technology belonging to the category of build up multilayer (BUM) PCB without core. For PCBs with application of ALIVH, electrical connection between layers is achieved in a soldering method instead of core board or vias. Put in another way, it is applied to produce BUM PCBs in a way of inner-layer interconnection with extremely high density.


AOI, short for automated optical inspection, refers to a type of inspection method based on an AOI equipment capturing images of PCB surface through numerous light source in order to inspect defects of PCB or PCB assembly.

Aspect ratio

Aspect ratio refers to ratio between PCB thickness and diameter of minimum via.


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

Assembly drawing

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

Assembly house

Assembly house refers to the place where PCBs and components are assembled together, containing assembly equipment inside such as printer, mounter, reflow oven etc.

Back drilling

Back drilling is mainly applied in multi-layer PCB fabrication. It aims to ensure signal integrity through drilling off stub between layers with no vias from the back.


PCB backplane refes to the supporting plane in circuit board, it plays a role of insulation.

Ball grid array (BGA)

Ball grid array, short for BGA, is a type of component package form applied in IC (integrated circuit) for surface mounting. It is usually used to forever fix devices like microprocessors on PCBs, capable of ensuring high-speed efficiency owing to its columns of balls playing roles of pins.

Bare board

A bare board refers to a PCB with no components mounted on it.

Base material

PCB base material is composed of resin, strengthening material and conductive material. Base material can be classified into different categories based on different perspectives, implementig different electrical functions in electrical products.

Blind via

Blind via refers to via connecting inner layers and can not be seen from the appearance of a PCB.


Board is the short form for printed circuit board. As an important electronic part, board is a carrier for electronic connection between electronic components.

Board house

Board house is the place where PCBs are fabricated.

Board type (single unit&panel)

Board type is the manufacturing method of PCBs in terms of volume. Usually, it is classified into two types: single unit and panel. For the former, PCBs are fabricated one by one. For the latter, panels are fabricated containing multiple single units.

Buried resistance board

Buried resistance board refers to a PCB with resistors buried inside in order to improve integrity of resistant components so that functions, reliability and electric performance of PCBs can be improved.

Buried via

Buried via refers to via connecting top layer to inner layers and it only can be seen from one side of board.


Cable refers to wire that is capable of transmitting electricity or heat.


CAD, a short form of computer aided design, refers to the situation in which designers implement design work with the help of computer and pattern equipment.

Carbon mask

Carbon mask is a type of liquid heat curing conductive carbon paste that is added to pad surface. Carbon mask is composed of synthetic resin, hardener and carbon toner. It is applied for jumper, key etc.

Ceramic substrate printed board

Bonded on the surface of ceramic substrate with alumina or aluminum nitride. This type of board features excellent insulating performance, high thermal conductivity, tremendous soft solderability and high adhesive strength.

Check plots

Check plots are a list of check items based on which inspection or test is implemented.

Chip-on-board (COB)

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


Circuit refers to a conducting loop composed by metal leads and electric and electronic components. Generally speaking, circuits can be classified into two categories: DC circuit and AC circuit.


Coating refers to solid continuous film that plays a role of protection, insulation or decoration.


Components, also called electronic components or parts, are compositions in electric equipment and devices including resistor, capacitor, potentiometer, valve, radiator etc.

Component hole

Component hole is responsible for component fixation of component on the board or electric connection between conductive patterns.

Component side

After components have been stably attached to PCB, PCB features two completely different sides. On one side, there are components. On the other side, it's flooded with soldering points for fixing components. Therefore, the side which contains components is called component side.


Connector refers to a component connecting two active components, transmitting current and signals.

Copper weight

Copper weight is used to indicate the thickness of copper on each layer of PCB, equivalent to the number of ounce copper for each area of 1square foot.

Countersinks/counterbores holes

Countersink/counterbore holes refer to holes that are cone-shaped and drilled in PCB.


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

Daughter board

As its name indicates, a daughter board is "daughter" of a "mother" board. Containing plugs, pins, scokents and connectors on it, daughter board plays a key role in internal connection within an electroic devices or computers.

Edge plating

Edge plating is copper plating stretching from top to bottom surfaces and to edges of board, applicable for edge soldering, connections etc.

Electroconductive paste printed board

Electroconductive paste printed boards are PCBs that are manufactured through silkscreen printing method. Electroconductive printing paste is applied to set traces and bridging and implement through-hole connection between metalized holes so that electroconductive patterns can be formed on the substrate or inside through holes.


EMC, short for electromagnetic compatibility, refers to the capability that equipment or systems are capable of running conforming to concerning requirements without producing unbearable electromagnetic interference to other equipment within the same electromagnetic environment.

External layer

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

Fabrication drawing

Fabrication drawing tells engineers and workers how a PCB should be manufactured. It primarily contains the following elements: board illustration, drill chart, section A-A, notes and title block.

Fine pitch

Fine pitch is a technological term belonging to assembly technology family. It deals with different IC packages in terms of micro spacing between leads.

First article

First article refers to the first or first few manufactured boards prior to volume production so that first article inspection can be undertaken to make some hidden problems exposed for expected performance of PCBs.


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.

Functional test

Functional test, also called behavioral test, aims to see whether the features and operational behaviors of a product can meet design requirements according to product attributes, operation descriptions and users' scheme.

Gold fingers

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


A grid, also called an electrical grid, is a network of interconnection, responsible for transmitting power.

Half-cut/castellated holes

Half-cut/castellated holes refer to holes that are drilled but remain half at the edge with copper on hole wall.

Half-cutted/castellated hole

Half-cut/castellated holes refer to holes that are drilled but remain half at the edge with copper on hole wall.


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.


IC, a short form for integrated circuit, also called microcircuit, microchip or chip, is actually a method to miniaturizing circuits including semiconductor devices and passive components that are constructed on semiconductor wafer surface.

Internal layer

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


IPC, an abbreviation of Institute of Printed Circuits, is a world-wide non-profitable industry association, contributing to helping enterprises to gain more competitive advantages and to achieve success in their business through achieving rigorous and scientific manufacturing standards.

Kapton tape

Kapton tape, also called polyimide tape, is an electrically insulating tape with features of heat resistance, inextensibility and thinness.


A laminate is the combination of different materials into a material with multiple layers so that the new material features higher strength, stability etc. A laminate is achieved through methods including heating, pressure, welding or adhesive.

Layer-to-layer spacing

Layer-to-layer spacing refers to the distance between layers, determining the difficulty degree of PCB manufacturing.


Legend is applied to mark component names and positions in order to ease assembly and maitenance.


In order to correct the errors generated in the process of PCB fabrication, Mark refers to a set of patterns used for optical localization. Mark can be classified into PCB Mark and local Mark.

Membrane switch

A membrane switch is an operating system integrating with key functions, indicator elements and instrumental panel, composed by panel, on-board circuitm, isolating layer and off-board circuit. A membrane switch has a precise structure and pretty appearance with excellent leakproofness and humid resistance.

Metal base printed board

Metal base PCB, also called metal core PCB, refers to the board whose base or core material is metal instead of normal FR4 etc.

Metal core printed board

Metal core PCB, also called metal base PCB, refers to the board whose base or core material is metal instead of normal FR4 etc.

Mother board

Mother board refers to a main board in a computer or electric device, carrying the key interconnections and components in order to implement functions of those devices.

Mounting hole

A mounting hole is applied to position or to get screws driven through it.

Multi-wiring printed board

Multi-wiring printed board is, in actual fact, equivalent to multi-layer printed circuit board, referring to PCBs with multiple layers of tracing and dielectric layer is between each pair of inner layers.

Multilayer pcb

Multi-layer PCBs refer to PCBs with multiple layers of tracing and dielectric layer is between each pair of inner layers. A multi-layer PCB contains at least three conductive layers and its electric connection is obtained through thru-holes across boards.


NPTH, short for non-plated through hole, refers to a hole with no plated copper on the hole wall, leading to no electric connections through this hole.


As a basic composition unit in SMT assembly, pad is a contact point responsible for connecting components with via.


A panel refers to a combination of boards composed by the same or different boards, by which PCBs are fabricated so that manufacturing efficiency will be improved.


Panelize, or panelization, refers to a method of PCB manufacturing through combining different boards into one panel so that manufacturing efficiency can be greatly increased.


Part, also called component, is compositions in electric equipment and devices including resistor, capacitor, potentiometer, valve, radiator etc.

Part number

Part number is the identification of parts for certain industries. It is applied to identify the specific part so that applications of wrong parts will be avoided.


Pattern is the drawing in which interconnection between traces is displayed.


PCB, short for Printed Circuit Board, is a provider of electric interconnection between components. Advantages of PCBs lie in great reduction of mistakes in terms of routing and assembly, increasing automatic level and manufacturing rate.

Peelable solder mask

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


A pick-and-place machine is for SMT assembly and it is responsible for picking SMDs and placing them on the correct positions on the board automatically.


Pins are leads stretching from internal circuits and connecting with peripheral circuits and all pins on an IC can be regarded as interfaces. The end of pin can be soldered on the board. With pad, a soldering point is formed.


Pitch is the distance between pin centers of SMDs.

Plated-through hole (pth)

Plated through hole applies to multi-layer PCBs, refers to a procedure in which plated through hole goes through plating, leading non-conductive part on the hole wall to metalization so that the hole wall can be fully conductive.


Prepreg, also called PP, is the key material for multi-layer PCB manufacturing. it is primarily composed of resin and strengthening material that is then classified into glass-fiber cloth, paper base, compound material etc.

Press fit holes

A press fit hole is a hole through which a contact terminal can be pressed into a PCB.

Printed wiring

Printed wiring applies photographic board manufacturing technology, that is, a process in which an image is etched on the copper or zinc board on which printing will then be conducted.


Printing is a link in PCB manufacturing process and it aims to make circuit pattern printed on the board.

Reference designator

A reference designator is used to indicate and specify each component that is described in a schematic or a PCB. A typical reference designator consists of an alphabet plus a number.


RF, short for radio frequency, identifies electromagnetic frequency that can be radiated to the space with a freuqency ranging from 300KHz to 300GHz. Moreover, RF can be also a type of high-frequency AC electromagnetic wave.

Route (track)

Route or track is an important link in PCB design procedure. It goes after placement during which each component or IC has been correctly placed on PCB. Then wires have to be reasonably arranged to connect components or ICs according to design rules.


A schematic is a drawing illustrating connecting principles between components on PCB. It is displayed with abstract and graphic signs instead of real pictures and a reference based on which PCB layout and routing can be implemented.


Silkscreen is applied to mark component names and positions in order to ease the difficulty of assembly and maitenance.

Slot hole

Slot holes are holes that are not round on a PCB and can or cannot be plated.


SMD, a short form for surface mounted device, is a type of components applicable for SMT. SMDs can go through pick and place machine for assembly.


SMT, short for Surface Mount Technology, is a type of circuit connection technology through getting SMDs with no pins or with short pins attached to PCB or other substrates and then implementing soldering by reflow soldering or wave soldering.

Solder bridging

Once electric soldering iron starts to be heated, tin wire is applied to be attached to the head of iron with flux melted so that soldering iron head becomes wet. Then soldering tin will become melting and a layer of soldering tin will be evenly soldered at the soldering iron head, which is called solder bridging. It is extremely important to soldering because it plays a key role in transmitting heat in the process of soldering and protecting soldering iron head from being oxidized.

Solder side

Solder side refers to the opposite side to component side when components have been attached to PCB. In a PCB, its solder side is always defined as its bottom side.

Solder mask

Since tin paste isn't needed to be attached with components assembled, a layer of material, usually epoxy resin, will be printed on the copper surface in order to avoid short circuits. This layer of material is calld solder mask with different colors such as green, red, black etc.


Substrate is the fundamental material for PCB fabrication. Generally speaking, substrate is copper clad laminate with functions of conductivity, insulation and support. Performance, quality, manufacturability, manufacturing cost and level largely depend on substrate material. Substrate material can be primarily classified into two categories: rigid substrate material and flexible substrate material.

Supported hole

A supported hole refers to the via that has pads on both sides of a PCB and inside via. Wall of a supported hole has a plating layer that plays a supporting role in components through soldering.

Surface finish

Since copper foil tends to be oxidized in natural environment so that tin paste fails to be attached, a protection layer is requried to be attached to copper foil. The main types of surface finishes include HASL, ENIG, ImAg, OSP etc.

Surface mount

Surface mount is a type of assembly technology through directly mounting or soldering SMDs on the surface of PCBs without the need to drill plug holes on PCBs.

Through-hole (thru-hole)

Thru hole refers to a hole passing through at least two layers in a multi-layer PCB.


Trace is the copper path printed on a PCB.


Tracing refers to the width of wires while spacing refers to the distance between wires.


UL is a renowned company specializing in independently contributing to safe scientific careers. It is capable of providing professional security solutions through three special business units: commercial and industrial business, consuming business and UL evironment health and creavitiy development business.

Unsupported hole

Unsupported hole is a hole that has a pad on the solder side while has no pad on component side. Moreover, there's no a metal layer inside the hole.


Via refers to holes connecting signals between layers in a PCB.

Via filled with resin

Via filled with resin is obtained through filling epoxy resin inside via after soldering through-hole wall. Then copper is soldered onto the surface of resin. Via filled with resin is a through hole with no dent on its surface so that soldering won't be influenced.

Via in pad

Thru hole on the pad is called via in pad that is a significant composition in multi-layer PCB. Its main functions primarily come as electric connection between layers and fixing or position of components.

Via plugged/filled with resin

Via plugged/filled with resin is obtained through filling epoxy resin inside via after soldering through-hole wall. Then copper is soldered onto the surface of resin. Via filled with resin is a through hole with no dent on its surface so that soldering won't be influenced.


V-scoring is incomplete cut off through a hole in a PCB, usually a panel, so that PCBs can be departed with a little effort.


Wire refers to cable that is capable of transmitting electricity or heat.