Glossary of Terms
This glossary is intended to provide some quick definitions of terms commonly used in the design and manufacture of printed circuit boards.
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PCB Terminology Glossary
Over 150 PCB Terminology Glossary You Have to Know (Updated Continuously)
Having a basic understanding of printed circuit board terminology can make working with a PCB manufacturing company much faster and easier. This glossary of circuit board terms will help you understand some of the most common words in the industry. While this isn’t an all-inclusive list, it is an excellent resource for your reference.
Short for any layer inner via hole, this is a type of technology used to build multi-layer BUM PCBs. This method uses solder to create an electrical connection between PCB layers. ALIVH often replaces traditional vias and is a useful production method for creating high-density BUM PCBs.
This term refers to the copper pad area that is left after a hole is drilled through it. This ring is measured from the edge of the pad to the edge of the hole and is an important consideration in PCB design, as it allows an electrical connection to be made from one side of the hole to the other.
This type of technology is commonly applied in SMT production lines with the goal of limiting the amount of tin involved in the stencil process. This is done by making a stencil on the board and creating openings at places where the solder ball tends to be produced so that the tin paste will flow to the openings.
Short for automated optical inspection, AOI refers to a type of inspection method used to find potential problems concerning soldering performance in multi-layer PCBs with components mounted on. The AOI equipment finds these issues by capturing images of the inner PCB surfaces, looking for any possible issues in terms of displacement, polarity etc.
Short for acceptance quality limit, AQL refers to the acceptable number of defective boards produced within a production run. These are identified, counted and removed during inspection. AQL is an important figure for monitoring the quality of an assembler’s production practices.
This word refers to the combination of multiple copies of the same PCB into a connected matrix of boards. An array may also be referred to as a panelized, stepped out or palletized PCBs. By assembling boards this way, the assembly process can be completed much more quickly. The Array # Up, in turn, refers to how many PCBs are included in the array.
Aspect ratio refers to the ratio between a PCB’s thickness and diameter of its minimum via. It’s best to keep aspect ratios low to improve plating quality and minimize potential via failures.
An assembly drawing is a reference depicting the assembly requirements of a PCB. These drawings will usually include the placements of components as well as the construction technologies, methods and parameters needed to make it happen.
A name used to refer to a manufacturing facility where PCBs and components are assembled. These houses will usually contain PCBA equipment such as a printer, mounter, reflow oven, and more.
Primarily applied in multi-layer PCB fabrication, back-drilling helps improve signal integrity by removing stubs from plated through-holes. These stubs are unnecessary portions of via that extend into the hole, potentially causing reflections and other disturbances that damage signals.
Short for ball grid array, this is a type of component packaging used in integrated circuits (ICs) for surface mounting. They can ensure high-speed efficiency since they use columns of balls instead of pins. BGAs are usually used to mount devices like microprocessors on PCBs permanently.
This is a shortened term for printed circuit board. This word also indicates the substrate upon which the PCB is printed. The board is an important electronic part, acting as a carrier for an electric connection between electronic components.
This indicates the manufacturing method of a PCB in terms of volume. Usually, a board is classified into one of two types: single unit or panel. In single unit manufacturing, PCBs are fabricated one by one. In panel manufacturing, on the other hand, multiple units of PCBs are manufactured in a single panel.
The term refers to a printed circuit board with resistors buried inside. This design improves the integrity of resistant components to improve the overall function and reliability of the PCB.
This term is used to refer to a via connecting a top layer to one or more inner layers. In other words, a buried via can only be seen from one side of the board when looking at it from the outside.
An acronym for computer-aided design, CAD refers to a designer’s use of computer and pattern equipment to develop and implement a PCB layout. The result is a three-dimensional graphic of the design, which, in this case, is the layout of a PCB.
CAM is an acronym for computer-aided manufacturing, and the files produced by this software are used for PCB manufacturing. There are multiple types of CAM files, including Gerber files for photoplotters and NC Drill files for NC Drill machines. These files are usually sent off to board and assembly houses for refinement and eventual manufacturing.
This is a type of conductive carbon paste that is added to the surface of a pad. Made with a combination of resin and carbon toner, carbon masks are heat-cured and are typically applied to jumpers, keys, etc.
This type of board is made with a ceramic substrate, to which other materials are bonded with alumina or aluminum nitride. The primary selling points for ceramic substrate boards are their excellent insulation capabilities, thermal conductivity, soft solderability and adhesive strength.
Shorthand for chip-on-board, this term is a type of bare chip SMT technology. COB involves directly mounting integrated circuits to a PCB instead of packaging them first. Common in mass-produced gadgets and toys, COB can be identified by a black glob of plastic on a PCB, called a glob top. Underneath the glob, the chip connects to the board with fine wires.
Alternatively called electronic components or parts, components are basic pieces that can be used to build electronic equipment and devices. Examples include resistors, capacitors, potentiometers, valves, radiators, etc.
This term refers to a transmitting component that connects two or more active components in an assembly. Usually, connectors consist of a plug and receptacle, which can be easily joined and separated.
The alternative to an analog circuit. Digital circuits operate in a binary fashion like a switch, exhibiting one of two results as a consequence of an input. This is a typical circuit for computers and similar equipment.
An abbreviation for a dual in-line package, a DIP is a kind of housing for integrated circuits. This housing will typically come in the form of a molded plastic container with two rows of attachment pins.
An acronym for design rule check, this is a software verification of a PCB layout. These are often used on PCB designs before production to ensure the design doesn’t contain any potential sources of error like small drill holes or traces placed too close together.
This is a type of solder mask film that is applied to a printed board that results in a higher resolution mask with finer line designs. This method tends to be more expensive than liquid solder masks.
This term is used to describe PCBs that are manufactured using a silkscreen printing method. The process involves applying an electroconductive printing paste to set traces and to implement stable through-hole connections.
An acronym for electromagnetic compatibility, EMC refers to the capability of a piece of equipment or system to run without producing excessive electromagnetic interference. Too much electromagnetic interference can interfere with or damage other pieces of equipment within the same electromagnetic environment.
This drawing is a way for designers to communicate a PCB design to engineers and workers. It will typically include an illustration of the board, locations and information about holes to be drilled, notes about the materials and methods involved, etc.
This is what the first manufactured board is called. First articles are usually produced in small groups before volume production begins so that designers and engineers can inspect the product for potential errors or performance problems.
This is a material rating for a flame-resistant material. It also refers to the most commonly used PCB substrate material. The name specifies that the resin material is capable of automatically extinguishing when it is aflame.
This refers to a “glob, ” a small ball of non-conductive plastic used to protect the chip and wire bonds on a COB. The glob is usually black in color and is resistant to thermal expansion, which prevents temperature changes from damaging the connection between the glob and the board.
These are connectors found on the edge of a PCB after the board has been plated with gold. Hard, smooth and flat, these fingers are excellent conductors, supporting edge-to-edge connections.
This refers to holes that are drilled on the edge of a board and plated, resulting in a half-circle hole on the edge of the PCB. This is common for PCBs designed for microchip testing.
An abbreviation of Institute of Printed Circuits, a worldwide non-profit association dedicated to the design of PCB wiring. The group helps enterprises achieve greater business success by helping them meet rigorous manufacturing standards, which, in turn, improve overall quality standards.
This term refers to the combination of different materials through heating, adhesive and welding methods to create a new material with multiple layers. The resulting material has greater strength and stability than the individual materials combined to create the laminate.
A membrane switch is applied to the front of a finished PCB. It indicates functions of the PCB and components, such as key functions, indicators and other parts. The membrane also provides protection for the PCB in the form of waterproofing and humidity protection.
A panel is a combination of boards produced simultaneously to improve efficiency during the manufacturing process. Once the process is finished, these panels are typically broken apart into their singular units before being used.
This is an identification method used in industry to differentiate parts from one another. It’s also used to identify specific parts, which is helpful in identifying problematic assembly batches and preventing incorrect product applications.
The material upon which the PCB is built. The PCB base material is typically composed of resin, metal, ceramic or another material with thermal and electric properties that support the PCB’s final function.
An abbreviation of Printed Circuit Board, a PCB is a board that contains a conductive material and components, which act in synchrony to produce a designed response. PCBs rely on electrical circuits, which are either printed or soldered onto the board to elicit the desired result. Printed circuit boards are available in a wide variety of shapes, sizes, and purposes to suit any industry or application.
Alternatively called a PTH, this is a procedure in which a through-hole is plated so that the whole wall can be conductive. This is often used as a contact point for through-hole components and can be used as a via.
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.
Alternatively called “Ref Des, ” this is the name of a component on a PCB. Typically, the component name begins with a letter or two, indicating the component class, followed by a number. These designators are usually printed on the silkscreen to help identify each component.
A technical drawing that illustrates the connections between PCB components. Schematics will often include abstract representations of components instead of pictures and is an important first step in PCB design.
This is an alternative way to say “short circuit, ” which is a connection with low resistance, resulting in excess current at the connecting point. This can cause serious problems in the PCB, including failure.
This is a layer of epoxy ink applied to a PCB that contains component names and positions. The labels included on silkscreens help to direct workers through the assembly process. Typically, silkscreens are white, which helps the labels stand out against the PCB’s solder mask.
Short for surface mount technology, this type of assembly technology directly solders SMDs to the surface of a PCB, rather than running components through thru-holes. This allows the board to function without drilling holes through it and also helps improve component density on the surface of the PCB.
This is a layer of material, usually consisting of an epoxy resin, which isn’t compatible with solder. This material is applied to the entire PCB, except those areas where content needs to be soldered. This process helps to physically and electrically insulate traces, preventing shorts. Solder masks are often green in color, though red and black are also common.
This is another word for “PCB base material”, the primary material for PCB fabrication. Generally, this material can be flexible or rigid and can be made of epoxy, metal, ceramic or other materials. The function of the end PCB will usually determine which substrate will be used for the project.
Since copper tends to oxidize in natural environments, a surface finish protects the layer from doing so. Oxidation can cause the tin paste to fail or solder incorrectly. The primary types of surface finishes include HASL, ENIG, IMAG, OSP, and others.
This is a type of via that has a dry film solder mask covering both its pad and its plated-thru hole. This solder mask insulates the via completely, protecting the PCB against shorts. Some vias are tented only on one side to allow for testing on the other.
This refers to a hole passing through at least two layers of a multi-layer PCB. It’s also used as a descriptor for components with parts or pins that run through a board to be soldered to another side.
This refers to the copper path printed on a PCB. It functions similarly to an electrical wire, connecting components on a PCB board. The word “trace” is also used to refer to a segment of the path.
Alternatively called a vector plotter or Gerber Photoplotter, this type of photoplotter draws a plot line by line using light manipulation technology. This method can produce larger plots, but it is also much slower than the more modern laser photoplotter method.