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.

This term refers to a type of component that is dependent on the flow direction of an electrical current. For example, a transistor, rectifier or valve would be considered active.

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.

It refers to circuits processing analog signals (continuous and variable signal). The output is non-binary within this type of circuit.

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.

This is a supporting plane on a circuit board that plays an insulating role.

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 term refers to a circuit board with no components mounted on it.

A blind via is a through-hole that connects inner layers, but it can’t be seen from the exterior of the PCB.

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 is another name for the facility where PCB boards are fabricated.

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.

A word used to describe the central section of an electronic component. It does not include the component’s pins, leads or accessory parts.

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.

Another word for a wire that is capable of transmitting electricity or heat.

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.

An acronym for computer-assisted engineering that refers to schematic software packages used to develop and visualize PCB designs.

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.

This is a list of check items that are based on which quality control inspection or test is implemented.

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.

It refers to a conductive loop composed of metal leads and electronic components. It falls into one of two categories: DC circuits and AC circuits.

A coating is a solid continuous film that either protects, insulates or decorates the PCB.

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 is a plated hole in a PCB that is made for a component. These holes are intended to facilitate either a component pin, termination or wire with an electric connection.

It’s a collection of components as represented in a CAD software system. It’s stored in a computer data file for later use.

This refers to the side of a PCB that contains components. The opposite side contains soldering points for components.

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.

This term is used to indicate the thickness of copper foil on each layer of a PCB. It’s typically expressed in ounces of copper per square foot.

These are cone-shaped holes that are drilled into a PCB. To allow a countersunk screw to sit flush with the PCB surface.

These cylindrical holes are meant to be used with a fastener so that the fastener sits flush with the PCB surface.

This is a groove that is dug on a PCB.

The “daughter” of a “mother” board, a daughter board contains plugs, pins, sockets, and connectors and plays a big role in internal connections for electronic devices and computers.

Another word for a graphic representation of an electronic component, which can also be called a footprint.

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.

A type of PCB that features traces and pads on both sides, rather than a single side.

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 another way to refer to where holes will be drilled in a PCB design.

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 type of connector is designed for the edge of a PCB, and it is most often used to facilitate an add-on card.

This is a term used for copper plating that stretches from the top to the bottom of a surface and along the edges of a board, allowing for edge soldering and connections.

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.

A shorthand for electrostatic discharge, which is caused by static electricity.

Also called an outer layer, an external layer is a layer on the outside of copper to which components attach.

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 term refers to a class of chip packages with micro-spacing between leads, typically below 0.050 inches.

These are metal pads found along the edge of a board. These are typically used when trying to connect two circuit boards together to expand the capacity of a computer, for example.

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.

Alternatively called behavioral test, functional test is designed to determine how well a product’s attributes meet design demands.

A type of CAM file used to control a photoplotter. It’s a standard way of communicating board specifications with manufacturers.

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.

“Grid” is another term for an electrical grid, an interconnected electrical network that transmits power.

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 acronym for high-density interconnector, an HDI is a type of PCB fabrication technology. It uses micro blind via technology to manufacture PCBs with high trace density.

The portion of a connector assembly that mounts directly to the printed circuit.

Short for integrated circuit, an IC is also called microcircuit, microchip or chip. Essentially, IC describes a method for miniaturizing circuits, especially for semiconductor devices.

This term refers to the inner layers in multi-layer PCBs. These inner layers are mostly signal layers.

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.

Alternatively called polyimide tape, this electrically insulating tape has numerous useful features, including heat resistance, inextensibility and thinness.

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.

Alternatively called a laser plotter, this type of photoplotter creates a finely-lined raster image of the end product. The result is a high-quality, highly accurate plot.

This is the distance between PCB layers. The lower the spacing, the more difficult the manufacturing process will be.

Another word for a terminal on a component.

This is a shorthand guide for marking component names and positions. Legends help ease the assembly and maintenance processes.

Shorthand for Liquid Photoimageable, an LPI is a liquid solder mask that is sprayed on a PCB. This method is more accurate, thinner than a dry film solder mask and more affordable.

A term used to refer to a set of patterns for optical localization. Marks can be classified into PCB Marks and local Marks.

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.

Metal core PCB refers to a type of PCB with a core material made of metal instead of plastic, resin or FR4 material.

A “mil” is another way to say a thousandth of an inch. It’s also the equivalent of a “thou. “

“mm” is another way to express a millimeter or a thousandth of a meter.

This is the main board in a computer or electric device. The motherboard carries key interconnections and components that support the primary functions of the device.

This hole is intended to secure the PCB to its final location in a device. To ensure there is no interference, all mounting holes are non-conductive and unplated.

This is a type of PCB with at least three conductive layers of trace and components.

A testing tool used to measure electrical values like current, resistance and voltage.

An equivalent to a multi-layer printed circuit board, this term refers to PCBs with multiple layers of trace, with dielectric layers between each.

This is a more common name for a Numeric Control drill machine. This type of machine is what assemblers use to drill holes in PCBs.

This is a pin or lead that is connected to at least one wire.

An acronym for non-plated through hole, NPTH refers to a hole with no plated copper on the hole wall. This means no electric connections can be made using the walls of this hole.

This is a short way of saying “open circuit, ” which is a break in an electrical circuit’s continuity. This prevents current from flowing and can disrupt the proper function of a PCB.

This is one of the most basic composition units of a PCB assembly. A pad is a contact point used to connect components with a via and is the point to which the components are soldered.

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 the act of grouping multiple PCBs into a panel to improve manufacturing efficiency. An alternative term is panelization.

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.

This is another word for a component, or a basic piece of electric equipment, such as a resistor, capacitor, potentiometer, valve, radiator, etc.

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.

All the data that is or could be used for a PCB design. This data is usually stored in a computer file.

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.

This is an acronym for Printed Circuit Board Assembly, where a company solders components to boards.

A solder mask or layer of solder mask that can be peeled from the board.

A device used in manufacturing to produce artwork onto the film by plotting objects instead of images.

A method of SMT assembly where a machine automatically picks up SMDs and places them in the correct positions on the board.

A terminal on a component. It is also called a lead.

The distance between pin centers of SMDs.

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.

This is a hole through which a contact terminal can be pressed into a PCB.

A process where a design is etched into conductive metal on board, producing a wire design for the PCB.

Part of the PCB manufacturing process where a circuit pattern is printed on the board.

An acronym for Printed Wiring Board, which is another name for a PCB.

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.

This is the process of melting solder to create a joint between a pad and a component or lead.

Short for radio frequency, RF is an electromagnetic frequency ranging between 300KHz and 300GHz. RF can also be a type of high-frequency electromagnetic signal.

Alternatively known as the Restriction of Hazardous Substances, RoHS is a European environmental protection law. Many global companies must follow RoHS standards to sell products in the EU.

This is the layout of a PCB’s wiring structure, which is important for the proper function of the PCB. As a verb, the act of routing means designing such wiring structures.

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.

A PCB design with traces and pads included on only one side of the board.

Non-round holes on a PCB that may or may not be plated. These are often required for specific components but are costly due to the labor needed to cut them.

Short for surface mount devices, it refers to components designed to be soldered on the surface of PCBs, rather than through a thru-hole.

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 the opposite of the component side and is usually regarded as the bottom side.

This term refers to the distance between wires on a PCB.

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.

This is a via with pads on both sides of the PCB. It’s also plated inside the via. This means the entire hole can support functions relating to thermal or electrical conductivity.

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 is shorthand for a thousandth of an inch. It’s another way to say “mil. “

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.

This term refers to the width of a PCB’s wires.

UL stands for Underwriter’s Laboratories, Inc., a renowned company specializing in establishing safety standards and independently assessing products according to these standards.

This type of hole has a pad on the solder side, but no pad on the component side. There is also no metal layer inside the hole. This means the hole has no conductive reinforcement.

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.

This term refers to plated through-holes that connect signals between traces on different layers of a PCB. These holes have conductive copper interiors to maintain an electrical connection.

This is a via that is filled with an epoxy resin. Once filled, copper can be soldered to the surface of the resin without influencing the final product.

Also called a thru-hole on the pad, a via in pad functions as an electric connection between layers. It is useful for multi-layer components or for fixing the positions of components.

This is an incomplete cut through a panel, which is often used to help break apart panels of PCBs into single units.

This refers to a conductive cable that can transmit electricity or heat. It also refers to a route or track on a printed circuit board.

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.

 A universal frame provides a solid frame to connect a frameless stencil.

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.

Also called Solder Cream, is used to solder a surface mount component lead to a corresponding land (pad) on a printed circuit board.

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.

Selective Gold indicates that a specific area in the interior of the board would be plated. This does not include gold fingers.

A laser cut stencil used when a single component needs to be re-worked when the rest of the components are already soldered to the printed circuit board.

Plasma Etching is a process used to remove copper from a PCB panel for special RF materials that cannot be processed with standard etching procedures.

The process to electroplate only select portions of a production PCB panel.

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.

A Non-Plated hole is a hole that is drilled after the copper plating process so that there is no plating in the hole. Often used for mounting holes.

The copper foil that is used for the conductive layers of the PCB.

A form of delamination just below the surface of the laminate material that is visible and shows as several small circular areas.

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.

The thickness of the fiberglass material before the soldermask, silkscreen or finishes have been applied to the PCB.

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.

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.

A plating process that does not use electroplating to transfer various metals to the copper base of a PCB. Most commonly used to apply Gold or Silver in an immersion process.

The process of taking the electronic data of the circuit patterns and transferring that data to the photo plotter or image device to apply the image to the film.

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.)

In PCBs this is a conductive area of the board, often an entire layer, that is usually connected to the power supply ground of the circuit.

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.

A fixed frame stencil is a laser cut stencil that is permanently attached to an aluminum 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.

Flash gold is hard gold with a maximum thickness of 3 micro inches. It is very thin and requires special handling.

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.

A DRC is performed with CAM software to verify the continuity of all conductors and routing within the manufacturers design rules.

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.

The chemical process of removing drilling debris that is left in the holes of a production PCB panel after being drilled.

A desktop stencil is a laser cut stencil that is used to apply solder past to surface mount component pads on a printed circuit board by hand.

When any copper or laminate materials in a PCB begin to separate after the boards have been manufactured.

The Date Code is added to the copper or silkscreen of the PCB during the manufacturing process. The date code shows the week and year that PCB was made.

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.

The thickness of the copper traces on a PCB. The most common thickness would be 1oz or 0.014″. 1oz refers to the amount of copper that would cover one square foot area.

The space between the copper traces on a PCB. Spacing may vary greatly on any individual board. Typical minimum spacing would be 0.007″ but could go down to extremes of 0.003″.

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.

This is the pattern of the copper on the final circuit board. This would include the traces, pads, etc. that make up the circuit on the board.

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.

For commercial PCBs this is the highest standard for manufacturing for high reliability circuits that would be used in flight controls or for some type of life support function.

Clad references the material used in manufacturing PCBs. Fiberglass material is “clad” with copper and is used as the starting place for manufacturing of the PCB.

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
Automatic   Insertion AI Manual MANU
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
Wrong Components WC Complete
Missing Components MC Width Control
Dry Soint/Short Solder Library
Defective Material Machine
Electrostatic discharge ESD Functions
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
Drawing DRG Print
Nozzle Information
Component   Feeder
Machine Initialize Value
Nozzle Basic Data
Recognition Base Data
Main pressure gauge
Half way continue
Locate pin
Running condition
Entrance stopper
PCB TBL on/off
Recognition command error
Positioner Miss
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