Also visit our FAQ
Semiconductor devices, such as transistors and diodes, that can change its basic characteristics in a powered electrical circuit, such as an amplifier and rectifier.
Air Gap (Line space)
The nonconductive air space between traces, pads, conductive matter, or any combination thereof.
An electrical circuit that provides a continuous quantitative output as a response from its input.
The width of the conductor pad surrounding a drilled hole. EXAMPLE: If the pad size is say, 35 mils, and the drilled hole is 25 mils then the annular ring WIDTH is 5 mils (35 = 25 + 5*2)
(For PCBFABEXPRESS online special promotions, we expect your design to have annular rings which are at least 5 mils wide. If your design has annular rings less than 5 mils, we can provide you a custom quotation for your order)
Used in photo plotting. Defines the shapes and sizes of Gerber file entities.
Artwork - CAD
Computer generated accuracy in layout used to produce a Master Pattern. Generally prepared at 1:1 scale using various software packages with special libraries of shapes to represent conductors and components and various Surface Mount Arrays.
The ratio of the board thickness to the smallest-hole diameter of the printed circuit board.
A drawing that shows all parts identified by their reference designator (C1, R1, U1, etc. like the silk-screened artwork), panel outline with datum and tooling hole positions. If auto-insertion is required, a list of X, Y coordinates of the parts may be helpful.
A drawing describing the locations of components on a PCB.
Automated Test Equipment (ATE)
Equipment that automatically tests and analyzes functional parameters to evaluate performance of the tested electronic devices.
American Wire Gage. A method of specifying wire diameter. The higher the number, the smaller the diameter.
Leads coming out of the ends and along the axis of a resistor, capacitor, or other axial part, rather than out the side.
"Bare Bones" PCBs
A special internet promotion that we offer for PCBs without any solder mask or legend on it.
An unpopulated PCB; i.e., a PCB with no components assembled on it yet. (Not to be confused with "Bare Bones", which is sometimes used to designate a PCB with no Soldermask or Legend).
Base Copper Weight
see Copper Foil.
Refers to the 45-degree angle that makes finger contact edges smooth, thus enabling easier insertion by the consumer.
Ball Grid Array is a leadless SMD developed in recent years. Unlike traditional SMDs, this type of device does not have pin leads. Instead it contains solder balls at the bottom of the device. These solder balls melt and make contact to the pattern on boards during assembly.
A via hole that does not pass completely through the printed circuit board Blind via starts from one side or another side and ends in any one of the inner layers.
Bill of Material. A component list with reference designators, part numbers, values, tolerance, description, and other information.
A common PCB panel format with board units connected to a panel by number of tabs around the units. Units break-away from panel after assembly. Panel profiling of this format may be routed or punched.
Poor registration between the hole and the pad on a printed circuit board to the degree that the hole is not within the area of the pad.
A condition that generally happens during the wave soldering operation where excess solder builds up and shorts out the adjacent conductors.
Built-In Self Test
An electrical testing method that allows the tested devices to test itself with specific added-on hardware.
A buried via connects two or more inner layers but no outer layer, and cannot be seen from either side of the board.
A Heavy trace or conductive metal strip on the Printed Circuit Board used to distribute voltage, grounds, etc., to smaller branch traces.
A capacitor used for providing a comparatively low impedance AC path around a circuit element.
Computer Aided Design.
Computer Aided Manufacturing.
The files used for manufacturing PCB including Gerber file, NC Drill file and Assembly Drawings.
A shaped corner to eliminate an otherwise sharp edge.
Pen plots, or plotted film, that are suitable for checking and for design approval by customers.
CEM1 or CEM3
PCB material, both CEM-1 and CEM-3 are epoxy/fiberglass over a paper core, differing only in the type of paper used. These materials are less expensive and more punchable substitutes for FR-4. Not a military grade material.
Ceramic Ball Grid Array (CBGA)
A ball grid array package with a ceramic substrate.
Separation between circuit entities. Generally refer to pad-pad, pad-trace, trace-trace, solder mask-pad, pad-drill, circuit-board edge, etc. These clearances are critical for board manufacturability and they should be set at a maximum when design allows.
A configuration in which a chip is directly attached to a printed circuit board or substrate by solder or conductive adhesives.
The individual circuit or component of a silicon wafer, the leadless form of an electronic component.
The process that gives a circuit the correct impedance value. The design engineer will specify the track impedance required. From this, a suitable manufacturing build will be chosen to the suit track widths and layer spacing on the design to meet the required impedance.
A thin layer of material, conductive, magnetic or dielectric, deposited on a substance surface.
Coefficient of Thermal Expansion (CTE)
The ratio of dimensional change of an object to the original dimension when temperature changes, expressed in %/ºC or ppm/ºC.
The Side of a PCB on which most of components are mounted.
Contact Angle (Wetting Angle)
The angle between the contact surfaces of two objects when bonding. The contact angle is determined by the physical and chemical properties of these two materials.
A coating that is generally sprayed, dipped, or brushed on to provide the completed Printed Circuit Board protection from fungus, moisture and debris.
Copper Foil (Base Copper Weight)
Coated copper layer on the board. It can either be characterized by weight or thickness of the coated copper layer. For instance, 0.5, 1 and 2 ounces per square foot are equivalent to 18, 35 and 70 um-thick copper layers.
A flux that contains corrosive chemicals such as halides, amines, inorganic or organic acids that can cause oxidation of copper or tin conductors.
The irreversible process of polymerizing a thermo-setting epoxy in a temperature-time profile.
Copper pouring or copper hatch
CAD/CAM terms. Refers to filling of an enclosed area (generally defined by 0-width polygon lines) with a solid or hatch pattern to create a copper plane or a section of copper plane.
Copper thickness and copper plating
Cooper thickness usually specified in terms of number ofoz/sq.ft (1/2 oz: 17.5um or 0.0007"/sq. ft; 1 oz: 35 um or 0.0014"/sq. ft, and etc.). The thickness of copper specified will be the final thickness of base material plus copper plating thickness. Generally base material comes with 1/4, 1/2, 1, and 2 oz, but finish copper thickness range from 1/2 to 4 or 5 oz.
A protrusion of the Printed Circuit Board edge that is manufactured to a configuration to mate with a receptacle that provides electrical and/or mechanical junction between the Printed Circuit Board and other circuitry.
Clinch is an operation where leads are bent at an angle after auto insertion to avoid component pop-up during wave-soldering.
Removal of an internal area of the board.
Dry Film Solder Mask
Integrated circuit chip as diced or cut from a finished wafer.
The placement machine bonding IC chips onto a chip-on-board substrate.
The attachment of an IC chip to a substrate.
An insulating medium between conductors.
Dual in-line package with two rows of leads from the base in standard spacing between the leads and row. DIP is a through-hole mounting package.
A circuit comprised of mostly integrated circuits, which operates like a switch (i.e., it is either "ON" or "OFF").
A component that has been fabricated prior to its installation (i.e., resistors, capacitors, diodes and transistors).
Used in photoplotting. D-Code assignment or aperture lists are used in defining shapes and sizes of Gerber file entities.
An NC file containing tool and coordinate information for drilling. Common format accepted are: EIA or Excellon in either binary or ASCII text file.
Dry - Film Resists
Coated photosensitive film on the copper foil of PCB using photographic methods. They are resistant to electroplating and etching processes in the manufacturing process of PCB.
Dry film solder mask
solder mask film applied to a printed board with photographic methods. This method can manage the higher resolution required for fine line design and surface mount. It is more expensive than liquid photoimageable solder mask.
Data exchange Format, commonly use in mechanical CAD systems.
A connector on the circuit-board edge in the form of gold plated pads or lines of coated holes used to connect other circuit board or electronic device.
The smallest distance from any conductors or components to the edge of the PCB.
Electrical test or bare board test refer to PCB short/open test.
The electrochemical deposition of reduced metal ions from an electrolytic solution onto the cathode by applying a DC current through the electrolytic solution between two electrodes, cathode and anode, respectively.
Electro-less gold plating
A gold plating process as a substitution of regular Tin/Lead plating. This type of plating applies a layer of thin gold (a fraction of micro-inches) to the entire circuit.
A coating applied during printed circuit board manufacture to protect copper features from oxidation and provide a very flat surface for soldering components.
Electrical Rule Check verifies design violation against pre-set parameters such as In/Out matching in schematic capture, or spacing rules in CAD/CAM systems.
Electro-statically applied Solder Resist.
The ratios of etch depth to the amount the resist is undercut during etching.
The process of selectively removing any material not protected by a resist using an appropriate solvent or acid.
The controlled removal by a chemical process, to a specific depth, of nonmetallic materials from the sidewalls of holes in order to remove resin smear and to expose additional internal conductor surfaces.
A drawing required for manufacturing. For circuit board fabrication, also referred to as drill drawing. A fabrication drawing should include: board outline and cut-outs with datum and proper dimensions; sizes and locations of all tooling holes, mounting holes and slots; drill pattern and symbols; a drill table with tool assignment and hole specs such as size/qty/tolerance/plating; material and finish specifications; part number and drawing number (if applicable) with revision; for multi-layer the layer stack; for finger contact the beveling specs.; finally, any notes needed to clarify requirements.
A plated through hole in a Printed Circuit Board that is used to provide electrical connection between a trace on one side of the Printed Circuit Board to a trace on the other side. Since it is not used to mount component leads, it is generally a small hole and pad diameter.
Fine pitch is more commonly referred to surface-mount components with a lead pitch of 25 mils or less.
A gold-plated terminal of a card-edge connector. Also see Gold Finger.
Fiducial marks are dots etched on board panel usually required by SMD assembly (provide viewing targets for camera to locate correct position).
Also called wave soldering. A method of soldering Printed Circuit Boards by moving them over a flowing wave of molten solder in a solder bath.
The material used to remove oxides from metal surfaces and enable wetting of the metal with solder.
Flame Retardent laminate made from woven glass fiber material impregnated with epoxy resin.
The electrical testing of an assembled electronic device with simulated function generated by the test hardware and software.
General-purpose epoxy/fiberglass woven fabric PCB material. Most vendors do not stock this material; instead, they use high-grade material like FR-4 as a substitution if you specify G-10.
A CAD/CAM data exchange format developed byIPC.
A widely accepted file format for photo plotting and is input to generate many formats of testing program and component placement program. There are two variants in Gerber file format: 274-D and 274-X (also called the extended Gerber or Gerber-X, with embedded aperture shape and sizes). PCB FAB EXPRESS accepts Gerber 274-X format only.
The woven glass fiber laminate impregnated with polyimide resin.
The gold-plated terminal of a card-edge connector. Also see Finger.
A material used to fabricate Printed Circuit Boards. The base material (fiberglass) is impregnated with epoxy filler which then must have copper laminated to its outer surface to form the material required to manufacture Printed Circuit Boards.
Generally required for contact fingers. Common specifications for this plating are: 0.00002" gold over 0.00015" nickel.
A two-dimensional network consisting of a set of equally spaced parallel lines superimposed upon another set of equally spaced parallel lines so that the lines of one set are perpendicular to the lines of the other.
A conductive plane as a common ground reference in a multilayer PCB for current returns of the circuit elements and shielding.
A condition where all unused areas (areas not consumed by traces or pads) of the Printed Circuit Board are left unetched and tied to the ground circuit throughout the board.
Hot Air Leveling, uses in conjunction with SMOBC (solder mask over bare copper), plates solder on component pads only (instead of Tin-plated traces and pad surface). Boards made toH.A.L have two advantages. First is the elimination of wrinkle effect on board surface after wave soldering (specially large copper presents). The second advantage is its ability to handle SMD assembly.
High Density Interconnect.
Airtight sealing of an object.
The number of holes per unit area on a PCB.
HPGL is a pen-plot format file generated from almost all CAD systems.
Impedance control refers to a dual process of designing and manufacturing of high speed circuit boards. As the frequency of a circuit goes up to a certain point (a few hundred Mega Hz), circuit traces will act as transmission lines and require impedance matching. With circuit of this type, trace characteristics are the function of its geometry and have to be calculated with other parameters such as material dielectric constant, board thickness and type of transmission lines; then proper trace width can be determined. Manufacturing of this circuit type requires tight control of circuit trace width.
Electrical test of individual component or part of the circuit in a PCB assembly instead of testing the whole circuit.
The Institute for Interconnecting and Packaging Electronic Circuits, the final American authority on how to design and manufacture printed wiring. In 1999, IPC changed its name from Institute of Interconnecting and Packaging Electronic Circuits to IPC. The new name is accompanied with an identity statement, Association Connecting Electronics Industries.
Interstitial Via Hole
An embedded through-hole with connection of two or more conductor layers in a multilayer PCB.
An industrial grade quality standard for acceptance of PCBs.
A CAD/CAM data exchange format developed byIPC. Accepted by some CAM systems for use of photoplotting, electrical testing and other CAM functions.
A composite material made by bonding together several layers of same or different materials.
The process of manufacturing a laminate using pressure and heat.
Land (same as pad), often referred as SMD Lands. SMD lands in most cases are suggested by component manufacturers and generally have standard codes such as 1206, SOT-23, SOIC14, etc. Consult component manufacturers or refer to IPC docs: ANSI/IPC-SM-782 for more information.
A small amount of current that flows across a dielectric area between two adjacent conductors.
A format of printed letters or symbols on the PCB, such as part numbers and product number or logos.
A collection of part information including symbol, foot-print, pad-stack and other cross reference information. Used in CAD/CAM EDA tools.
Liquid Photo-Imageable solder mask that uses photographic imaging to control a thinner mask deposition than the dry film solder mask.
A term defining the ability of a board design to meet manufacturing requirements.
An accurately scaled pattern, which is used to produce the Printed Circuit within the accuracy specified in the Master Drawing.
MCM-L is a high density interconnect device. Generally consisting of glass reinforced laminates up to 22 layers with blind and buried via technology, this product allows interconnect and attachment of bare integrated circuit die. Using a refined subtractive process, fine line width and spacing technology along with small hole drilling can be achieved. Intermediate conformal packages (e.g. DIPs, Quad Flat Packs, PGAs, SMT) are eliminated which results in size, weight, and power savings. Multiple methods of attachment of the bare die promote flexibility and reduced cycle times. Military certification is available.
MCM-L can be used where size, weight, and speed are of concern. When high density, low cost interconnections are required MCM-L packaging should be used. Space, military, commercial, automotive, and flight hardware are prime candidates for MCM-L. While limited to approximately 350 Mhz clock speed, most products can be designed into this lightweight subminiature package. Multiple methods of attaching the bare die are available, e.g. wire bond, TAB, flipchip.
Minimum Conductor Width
The smallest width of any conductors, such as traces, on a PCB.
Minimum Conductor Space
The smallest distance between any two adjacent conductors, such as traces, in a PCB.
A military grade quality standard for acceptance of PCBs.
A military grade quality standard for design layout of PCBs
A unit used commonly in the PCB industry to measure traces, spaces, hole diameters etc.
1 mil = 1/1000 inch = 0.001 inch
1 inch = 1000 mils
A destructive test normally showing a cross section of a hole so that the plating thickness can be measured.
Minimum line space
Smallest air gap between copper features.
Circuit boards consisting of three or more layers of printed circuits separated by laminate layers and bonded together with internal and external interconnections.
Also called the Back Plane, or Matrix Board. A relatively large Printed Circuit Board on which modules, connectors, subassemblies or other Printed Circuit Boards are mounted and interconnections made by means of traces on the board.
Numeric Control drill machine used to drill holes at exact locations of a PCB specified in NC Drill File.
An ASCII list describes logical connections between component pins. Generated from schematic capture systems for transferring logical connections to layout systems. Other net-lists are generated from CAD/CAM systems for board test and in-circuit test purposes.
A pin or lead to which at least two components are connected through condcutors.
A type of hole on a circuit board generally used as mounting holes for the board. The wall of these holes/slots are not plated thus no connection between layers.
The portion of a conductive pattern for connection and attachment of electronic components on the PCB. Also called Land.
In CAD layout EDA systems, padstack is a collection of pad shape and size information
Printed Circuit Board. Also called Printed Wiring Board (PWB).
Personal Computer Memory Card International Association.
Printed Electronic Component.
A manufacturing operation of assembly process in which components are selected and placed onto specific locations according to the assembly file of the circuit.
The center-to-center spacing between conductors, such as pads and pins, on a PCB.
Plastic Leaded Chip Carrier (PLCC)
A component package with J-leads.
A uniform coating of conductive material upon the base metal of the Printed Circuit Board.
PTH (plated-through Hole)
A plated hole used as a conducting interconnection between different layers or sides of a PCB either used as connection for through-hole component or as a via.
Material deposited as a covering film on an area to prevent plating on this area.
Plated Holes (Plated Through Holes)
Holes with plating in them to conduct electricity, as opposed to Non-Plated through holes which do not have plating in them. Plated holes are used to connect traces across the different layers in the PCB.
A general term in CAM editing used to prepare data in panel format.PC-103 or PC-104: A common type of solder mask, which has a shiny lighter finish than SR-1000. Generally available colors are green, blue, red, white and black.
Photoplotting or photoplot
Photoplotting is an electronic optical process to scan rasterized image data on films. Sometimes referred to as laser plotting. A photoplot is a film generated by aphotoplotter, or referred to as artwork required for PCB fabrication.
A type of hole on a circuit board generally used to mount components and to createvias. The wall of these holes/slots is plated forming a circuit between layers.
Is an element of new product introduction, which involves building initial quantities, in short production runs, of an electronic product for testing, as well as for design validation and manufacturability refinement. The prototyping process involves nearly all aspects of a product prior to volume production and can significantly streamline the design and product development process, while substantially reducing costs.
A PCB panel format with board units punched out from the panel then reset back into the same location by second operation.
A lead extending out the side of a component, rather than from the end. Reference designator: Component ID used in schematic and PCB design, such as C1, C2, R1, R2, etc.
The alignment of a pad on one side of the Printed Circuit Board (or layers of a multilayer board) to its mating pad on the opposite side.
Melting, joining and solidification of two coated metal layers by application of heat to the surface and predeposited solder paste.
Coating material used to mask or to protect selected areas of a pattern from the action of an etchant, solder, or plating.
A variant of Gerber data, which contains aperture shape information in addition to the usual tool selection and movement commands.
Restriction of Hazardous Substances, is one of a handful of European legislation intended to eliminate or severely curtail the use of cadmium, hexavalent chromium, and lead in all products from automobiles to consumer electronics.
Route (or Track)
A layout or wiring of an electrical connection.
RF (radio frequency) and wireless design
A circuit design that operates in a range of electromagnetic frequencies above the audio range and below visible light. All broadcast transmission, from AM radio to satellites, falls into this range, which is between 30KHz and 300GHz.
Route and Retain
Internal routing such that PCBs remain intact on the panel for easy assembly. Later these boards are "snapped apart".
In a PCB CAD layout application, routing refers to making manual/automatic-wiring connections to logical nodes in a net. In PCB fabrication, routing refers to board edges profiling by running an NC program.
A process for transferring an image from a patterned screen to a substrate through a paste forced by a squeegee of a screen printer.
An assembly term referring to arrangement of axial/radial components in their order of insertion sequence, and to prepare a new tape/reel by a sequencer.
Short circuit. 1. An abnormal connection of relatively low resistance between two points of a circuit. The result is excess (often damaging) current between these points. Such a connection is considered to have occurred in a printed wiring CAD database or artwork anytime conductors from different nets either touch or come closer than the minimum spacing allowed for the design rules being use.
Silk Screen (Silk Legend)
Epoxy-ink Legend printed on PCB. The most common colors used are white and yellow. Also known as Legend or Nomenclature.
Solder mask (soldermask)
A non-conductive surface screened or laminated on the PCB to protect the circuit from oxidation, and shorts during wave-soldering. Common solder mask types are: SR-1000, PC-103/4,LPI.
Solder connecting, in most cases, misconnecting, two or more adjacent pads that come into contact to form a conductive path.
Round solder balls bonded to the pads of components used in face-down bonding techniques.
A band of wire removes molten solder away from a solder joining or a solder bridge or just for desoldering.
Form of solder to be printed on SMD pads by using a stencil in assembly.
Small Outline Integrated Circuit (SOIC)
An integrated circuit with two parallel rows of pins in surface mount package.
Solder mask over bare copper.
Surface Mount Device.
Surface Mount Technology.
Distance between same points on adjacent SMD pads.
Refers to the center-to-center lead spacing of axial and radial components.
A common type of solder mask, with a darker matte finish than PC-103/4. Generally available colors are green, blue, red, white and black.
Stencil is a cooper foil screen with SMD pads etched openings used for solder paste printing in assembly.
A general term in phototooling referring to an image unit, which is stepped and repeated into multiple image units.
Time Domain Reflectometer, a device that a board house can use for measuring characteristic impedance of a conductor on a printed board, thus insuring an accurate build for controlled impedance.
A process for strengthening the connections between pads and tracks. Typically used when the annular ring is 0.005" or less.
A via with dry film solder mask completely covering both its pad and its plated-thru hole. This completely insulates the via from foreign objects thus protecting against the accidental shorts, but it also renders the via unusable as a test point.Sometimes vias are tented on the topside of the board and left uncovered on the bottom side to permit probing from that side only with a test fixture.
Temperature Coefficient (TC)
The ratio of a quantity change of an electrical parameter, such as resistance or capacitance, of an electronic component to the original value when temperature changes, expressed in %/ºC or ppm/ºC.
A specific point in a circuit board used for specific testing for functional adjustment or quality test in the circuit-based device.
A method for determining whether sub-assemblies, assemblies and/or a finished product conform to a set of parameter and functional specifications. Test types include: in-circuit, functional, system-level, reliability, environmental.
This term defines the ability of meeting electrical requirements.
Thermal relief or heat relief
A thermal relief or heat relief is a type of circuit pad used at a location where there is a component pin or fan-out via that connects to a copper plane. The purpose of using a thermal relief pad is to provide a connection while dissipating heat through the big copper plane.
A type of hole on a circuit board generally used for component pins andvias. The wall of these holes/slots are plated creating a circuit between layers where required.
The most commonly used solder plating process in the PCB industry. The process applies 0.0004"(min.) to 0.0008"(max.) ofSn/Pb on all conductive areas. However, Tin-lead plating may not be a suitable a process if you have SMD on the board.
Also called Fabrication Hole, Pilot Hole, or Manufacturing Hole.
A type of outsourcing method that turns over to the subcontractor all aspects of manufacturing including material acquisition, assembly and testing. Its opposite is consignment, where the outsourcing company provides all materials required for the products and the subcontractor provides only assembly equipment and labor.
Underwriter's Laboratories. A popular safety standard for electrical devices supported by many underwriters.
A plated-through hole used for interconnection of conductors on different sides or layers of a PCB.
A board profiling process that involves cutting straight lines from both sides of board. This profiling method is more time efficient than a traditional routing process, suitable for medium to large volume production with panels requiring only straight line cuts. With this process, no space is needed between units.
Interconnection between circuit layers. Common type of via connects traces on all layers, blind via or buried via are connected to defined layers only.
A manufacturing operation in which solder joints are soldered simultaneously using a wave of molten solder.
Warping generally refers to finished board warp and twist. All boards may have a certain degree of warp as a result of manufacturing, especially if materials contain a high volume of moisture. Therefore you should specify your warping tolerance.
A machine soldering process involving pre-heat, fluxing, soldering, and cleaning. Most commonly used solder composition is 63%Sn/ 37%Pb.
General type of solder mask applied by screen. Usually refers to types of solder mask like SR-1000 and PC-103/4. LPI is NOT a type of wet mask.
The method used to attach very fine wire to semiconductor components (dice) to interconnect these components with each other or with package leads. The wires might be 1 to 2 mils in diameter and made of aluminum containing 1% silicon.
Zero width represents an outline shape drawn by "0" thickness line width. The most commonly used definition is the polygon to draw copper fill, or shapes defining the drawing limit of an entity.