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.
We will continue to increase this list, so I hope to help you!
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.
Zip file is a compressed file that contains the needed design files for the manufacturing of a printed circuit board. As an example for a two layer board the files included would be Gerber files for the Top Copper, Bottom Copper, Top Soldermask, Bottom Soldermask and Top Silkscreen. It would also include the NC Drill file and a Fabrication Drawing.
Stencil Fiducials are alignment marks. If your screen printer is equipped with a vision system, fiducials half cut in the stencil to allow for the printer to automatically align the board with the stencil. If you are manually aligning the stencil with the board, you could either full cut the fiducials or just use the surface mount pads.
Soft gold is commonly referred to as “wire bondable gold”. It is softer than other gold finishes which allows it to be bonded to more easily for stronger and more conductive connections. The gold does not disappear at the point of soldering or wire bond which produces a stronger welded joint.
Used to apply solder paste to a printed circuit board to aid in the soldering of surface mount components. The stencil is usually stainless steel and can be used many times in the electronics assembly process.
Refers to a short circuit in the circuit board. A short could have been accidentally created in the design of the board or is a result of an error in the manufacturing process. An electrical test can be used to identify the short to prevent it from passing final inspection.
OSP is an organic chemical finish that is applied to the copper. The shelf life is very short with OSP and the boards should be used very soon after applying the finish.
A NRE is any type of onetime costs related to the manufacturing of a printed circuit board. These costs will vary but could include Tooling or Engineering costs, electrical test etc.
Similar in appearance and use as Leaded Solder with Hot Air Solder Level. Contains a mix of 99.3% Tin and 0.6% Copper. It may be referred to as SN100CL. The temp at which it flows is around 515 degrees as compared to around 485 for Leaded Solder.
Commonly referred to as White Tin, Immersion Tin is a chemical process which applies a very thin layer of tin to the copper. The appearance is mostly white, has a shorter shelf life and is good for tight pitched components.
The purpose of this silver plating is to protect the copper from corroding as well maintaining its solderability. It does have a shorter shelf life than some other finishes and must be shipped with separator sheets to prevent tarnishing.
HASL, Hot Air Solder Level is a common finish type for PCBs. The PCB panel with exposed copper is lowered into a liquid bath of solder then quickly raised out of the bath and moved passed jets of hot air that clear off the excess solder leaving only the solder on the exposed copper areas.
Hard Gold is an electrolytic process and has hardeners in it for durability. It is plated over a nickel finish and may also be referred to as Deep Gold. (The term Deep Gold is used to indicate that full panels are placed in the plating tank prior to the application of soldermask.)
A laser cut stencil that will be placed inside a universal frame. A frameless stencil will have holes cutout along the each edge of the stencil so that it can be attached to a universal frame.
This is an electrical test method of bare circuit boards. The flying probe machine uses several arms with probes on the end that work together to touch the test points on the circuit board to determine if there are any opens or shorts on the board.
Small adjustments are made to normalized Gerber data it compensate for the amount of copper that will be etched from the production panel. This can vary depending on the copper weight and is determined by the CAM operator based on quality controls.
The electro-deposition of metal coating on a conductive object. The metal may be conductive or non-conductive. The object is placed in an electrolyte and connected to one terminal of a DC voltage source. The metal to be deposited is similarly immersed and connected to the other terminal. This creates a current flow from the metal to the conductive material thus depositing the material. In PCB manufacturing it is used to apply copper to the hole walls and copper conductor pattern.
ENIG is a very thin amount of Gold applied over Nickel. The nickel is plated onto the copper prior to the application of Gold and acts as a barrier to prevent the Gold and the Copper from migrating into one another. The gold will disappear when soldered, as it is absorbed in the process. Excellent for very fine pitched components.
Similar to ENIG but applies palladium over the nickel prior to the application of the gold. This prevents any problems of corrosion between the nickel and gold and makes it a very “universal” surface finish. Can be used for fine pitched components as well as gold wire bonding.
The process of depositing a conductive material from an autocatalytic plating solution without the application of an electrical current. Used to apply a thin amount of copper prior to copper plating to improve the possible connecting in the hole walls. Is also used when applying various finishes to the board such as ENIG (Electroless Nickel Immersion Gold).
The process of depositing a conductive material from a plating source using the application of an electrical current. This is used for plating in the hole walls as well as adding plating the copper pattern.
Electrical Test is the process of testing the board for continuity and isolation. (opens and shorts). Typically the end points of all nets are checked for opens and shorts. It does not include functionality testing of the PCB.
Dielectric refers to the fiberglass material in a PCB. The material is non-conductive and acts as an insulator for the electrical circuit in the PCB. The properties of the dielectric material can have an effect on the electrical circuit.
A counterbore is cylindrical flat-bottom hole that enlarges another drilled hole. It is typically used when a fastener, such as a socket head cap screw, is required to sit flush with the surface of the PCB.
A multi-layer circuit board is made up of a core, prepreg and copper foil. The core is fiberglass material that has copper clad to it and will vary in thickness depending on the number of layers and the final PCB thickness required.
The Copper Weight (also called Finished Copper Weight) is the total thickness of copper on the surface of a PCB. There are several processes that effect the final copper thickness. It is measured in oz/sq ft. For example 1 oz = a thickness of 0.0012″.
Electrical impedance is the measure of the opposition (resistance) that a circuit presents to the passage of a current when a voltage is applied in an alternating current circuit. Controlled Impedance is the process of manufacturing a PCB to meet a specific impedance requirement.
Adjusting the thickness of the circuit boards materials (fiberglass) in order to create a specific electrical effect. Most often used in multi-layer boards in order to obtain the desired impedance.
Refers to the computer control that is used with modern day machinery. It is most often used in the PCB manufacturing process with CNC Drill Machines as well as Rout machines that cut the individual boards away from the production panels.
Is used to measure the electrical breakdown properties of the insulating material used in PCBs. It is primarily used to assess electrical safety especially for human users of electrical devices. Material manufacturers will provide these details in their material specifications sheet.
A measurement of the amount the PCB material will change per degree of temperature. This is a key factor in when determining which material is the best one to use for a given circuit design. Material manufacturers will provide these details in their material specifications sheet.
A clearance (also called isolation) is space used to create a separation from a power or ground layer near a plated hole on an inner layer. A clearance will prevent a short from the plated hole to either the power or ground plane.
Usually referring to the final thickness of the printed circuit board. This would include the fiberglass, soldermask and silkscreen and the board finish. The most commonly used thickness is 0.062″ but many options are available.
A beveled edge is typically used to make the leading edge of a circuit board more pointed so that it can be inserted into a connecting device. The standard is a 30 degree bevel. An example would be a PCI card that is inserted into a PCI slot in a PC.
SMT processing factory commonly used terms and their abbreviations
|Terms||abbreviation||SMT/AI equipment commonly used terms|
|Surface Mounting Technology||SMT||Terms||abbreviation|
|In Circuit Tester||ICT||Origin||ORG|
|Printed Circuit Board||PCB||Head|
|Industrial Production Alcohol||IPA||Automatic||AUTO|
|Infra-Red Ray Reflow||IR||Enter|
|Surface Mount Component||SMC||Semi-Automatic||SEMI|
|Surface Mount Device||SMD||End Of Program||EOP|
|Quality Improve Team||QIT||Continuous||CONT|
|Surface Mount Line||SML||Switch|
|Quality Cost Delivery||Q.C.D||Mark|
|Statistical Quality Control||SQC||Nozzle|
|Industrial Engineering||IE||Execution Start Block|
|Automatic Insent Line||AIL||Transfer Check|
|Missing Components||MC||Width Control|
|Dry Soint/Short Solder||Library|
|Dip or Dip In Put||DIP||Format|
|Fault Output Rate||F.O.R||Insert|
|Finally Circuit Testing||FCT||Next Page|
|Bill Of Materiel||BOM||Copy|
|Part Per Million||PPM||Clear|
|Machine Initialize Value|
|Nozzle Basic Data|
|Recognition Base Data|
|Main pressure gauge|
|Half way continue|
|PCB TBL on/off|
|Recognition command error|