Glossary of Terms

This glossary is designed to provide some quick definitions of terms commonly used in the design, fabrication, and assembly of printed circuit boards. It’s a growing list that we contribute to frequently so we hope you will find it useful.

Activating A treatment that renders nonconductive material receptive to electroless deposition.

Additive Process A process for obtaining conductive patterns by the selective deposition of conductive material on the clad or unclad base material.

Aluminum PCB Aluminum PCB is also referred as metal core printed circuit board (PCB), IMS (insulated metal substrate) PCB, and MCPCB.

Annular Ring That portion of conductive material completely surrounds a hole.

AOI AOI stands for Automated Optical Inspection, which is an inspection tool in Printed Circuit Board Assembly to efficiently and accurately detect SMT assembly production errors before PCB assemblies leave the facility.

Aperture file, also known as D-code lists, is a text file describing the size and shape of each element on the PCB board. D-code lists are not necessary if your files are saved as Extended Gerber with embedded Apertures (274X).

Array A group of elements or circuits (or circuit boards) arranged in rows and columns on a base material.

Artwork An accurately scaled configuration used to produce the artwork master or production master.

Artwork Master The photographic film or glass plate that embodies the image of the PCB pattern, usually on a 1:1 scale.

ASCII American Standard Code for Information Interchange. Â Pronounced “ass-key.” is the character sets used in almost all present-day computers. US-ASCII uses only the lower seven bits (character points 0 to 127) to convey some control codes, space, numbers, most basic punctuation, and unaccented letters a-z and A-Z. Newer codes use more bits in a RS 274x format for more object definition.

Aspect Ratio A ratio of the PCB thickness to the diameter of the smallest hole.

Assembly A number of active and passive electronic components (parts), subassemblies, or any combination thereof joined together. We provide turnkey PCB and assembly services.

Assembly Drawing A drawing showing the locations of components, with their reference designators, on a printed circuit board. Also called component locator drawing.

ATE ATE stands for Automatic Test Equipment that automatically analyzes functional or static parameters in order to evaluate performance.

AutoCAD A drawing software standard which is used by RF and silicon chip packaging designers, saved in a DXF format to convert to Gerber for PCB manufacturing.

AXI AXI stands for Automated X-ray Inspection, has grown as a new type of technology in PCB Assemblies inspection. Similar to non-contact optical inspection, X-ray Inspection produces images of the PCBA object.

B-Stage Material Sheet material impregnated with a resin cured to an intermediate stage (B-stage resin). Prepreg is a popular term.

B-Stage Resin A thermosetting resin that is in an intermediate state of cure.

Backup Material A layer composed of phenolic, paper composite, or aluminum foil-clad fiber composite is used during fabrication to prevent Burrs and to protect the drill table.

Barrel The cylinder is formed by plating through a drilled hole.

Base Copper The thin copper foil portion of a copper-clad laminate for PCBs. It can be present on one or both sides of the board.

Base Material The insulating material upon which a conductive pattern may be formed. It may be rigid or flexible or both. It may be a dielectric or insulated metal sheet.

Base Material Thickness The thickness of the base material excluding metal foil or material deposited on the surface.

Bed-Of-Nails Fixture A test fixture consisting of a frame and a holder containing a field of spring-loaded pins that make electrical contact with a planar test object (i.e., a PCB).

Bevelling An angled edge of a printed circuit board usually for gold fingers. The standard bevelling angles are 30, 45°and 60°.

BGA BGA is the abbreviation of Ball Grid Array. A ball grid array is a type of surface-mount packaging used for integrated circuits. BGA packages are used to permanently mount devices such as microprocessors. A BGA can provide more interconnection pins than can be put on a dual in-line or flat package. The whole bottom surface of the device can be used, instead of just the perimeter.

BGA Assembly BGA is the abbreviation of Ball Grid Array. We have been providing BGA assembly services including BGA Soldering service, BGA Re-balling Service, and BGA Rework Service in the Printed Circuit Board Assembly industry for many years.

Bleeding A condition in which a plated-through hole discharges process materials of solutions from voids and crevices.

Blind Via Blind Via is a conductive surface hole that connects an outer layer with an inner layer of a multi-layer printed circuit board (PCB) without penetrating the entire board.

Blister A localized swelling and separation between any of the layers of a laminated base material, or between base material or conductive foil. It is a form of Delamination.

Blow Hole A solder joint void caused by out-gassing of process solutions during thermal cycling in SMT assembly.

Board In the PCB industry, the board stands for printed circuit board, which is built and comprised of laminate and copper traces with interconnecting holes.

Board House A manufacturer of printed circuit boards.

Board Thickness The finished PCB Board Thickness

Board Vendor Board Vendor can be printed circuit board manufacturer, supplier, and provider.

BOM Bill of Materials pronounced “bomb”. A list of components of a printed circuit board assembly. For a PCB the BOM must include reference designators for the components used and descriptions that uniquely identify each component. A BOM is used for ordering parts and, along with an assembly drawing. For more about required BOM information, please refer to Sample BOM.

Bond Strength The force per unit area required to separate two adjacent layers of a board by a force perpendicular to the board surface.

Book A specified number of stacks of Prepreg plies which are assembled for Curing in a lamination press.

Bow The deviation from flatness of a board, characterized by a roughly cylindrical or spherical curvature such that if the board is rectangular. Its four corners are in the same plane.

Breakdown Voltage The voltage at which an insulator or dielectric ruptures,or at which ionization and conduction take place in a gas or vapor.

Bridging The formation of a conductive path between two insulated conductors such as adjacent traces on a printed circuit board.

Build-up Buildup -PCB or Board Build-up: A PCB is defined by the PCB designer with a number of copper layers in a well-defined sequence. The pattern in each copper layer combined with the drill patterns and the copper plating of these drilled holes, form an electrical net that is responsible for connecting the pins of components to other pins of other components. The sequence in which these copper layers are defined is called the PCB Buildup, PCB Build-up, Board Buildup, or Board Build-up. The printed circuit board manufacturer will fabricate the PCB board as per the Buildup. See Stack-up, or Extra…

Buildability Team meeting to review customer PCB designs against manufacturing process capabilities. Used to identify possible failure modes prior to PCB fabrication.

Buried Via Buried Via is a via hole that does not extend to the surface of a printed circuit board but only spreads in inner layers.

Burr A ridge left on the outside copper surface after drilling.

C-Stage The condition of a resin polymer when it is in a solid-state with high molecular weight.

CAM Files CAM stands for Computer-Aided Manufacturing. CAM files are the data files used directly in the manufacture of printed circuits. The types of CAM files Gerber file, which controls a photoplotter or LDI exposure unit.

Capacitance The property of a system of conductors and dielectrics that permits the storage of electricity when a potential difference exists between conductors.

Capture Land (Via Top Land) Land where the microtia originates; varies in shape and size based on use(i.e., component mounting, via entrance and conductor).

Carbon Ink Carbon Ink can be used for keyboard contacts, LCD contacts, and jumpers. The printing is performed with conductive carbon ink. Carbon elements must resist soldering or HAL. Insulation or Carbon widths may not reduce below 75% of the nominal value. Sometimes a peelable mask is necessary to protect against used fluxes. Registration measuring will be performed using a selected reference mark in the copper pattern. These targets are automatically integrated into our production panel frames. Refer to Carbon Ink PCB in our PCB blog.

CCL CCL is the abbreviation of Copper Clad Laminate, which is a base PCB material. With glass fiber or wood pulp paper as reinforcing material, a CCL is a type of product through lamination with copper-clad on either one side or both sides of reinforcing material after being soaked in resin.

CEM-1 A older NEMA grade printed circuit laminate having a substrate of woven glass surfaces over a cellulose paper core and a resin binder of epoxy. It has good electrical and mechanical properties, It is inexpensive and can be punched. CEM-1 PCB can only be manufactured single-sided, but not double-sided or multilayered.

Chamfer A broken corner to eliminate an otherwise sharp edge.

Characteristic Impedance A compound measurement of the resistance, inductance, conductance, and capacitance of a transmission line expressed in ohms. In a printed circuit board, its value depends on the width and thickness of the trace, the spacing from the conductor to the ground plane(s), and the dielectric constant (Dk or Er) of the insulating dielectric.

Circuit The interconnection of a number of devices in one or more closed paths to perform a desired electrical or electronic function.

Circuitry Layer A layer of a printed board containing conductors, including ground and voltage planes.

Clad or Cladding A relatively thin layer or sheet of metal foil that is bonded to a laminate core to form the base material for printed circuits.

Cleanroom A room in which the concentration of airborne particles is controlled to specified limits.

Clearance A clearance (or isolation) is a term used to describe the space from power/ground layer copper to through-hole.

Clearance Hole A hole in the conductive pattern larger than, but concentric with, a hole in the PCB board base material.

Coated Copper Coated Copper Materials are comprised of copper foil, coated with a dielectric material that can be directly bonded to the sub-composite. They differ by whether they are wet processable or not. In wet processable coated copper, the vias are formed by acidic or alkaline etching or the dielectric may be made etchable by photographic definition. In non-wet processable-coated copper materials, vias are formed utilizing methods such as plasma, laser drilling, or mechanical drilling. The materials coated are typically epoxy, polyimide, or acrylic.

COB COB is the abbreviation of Chip On Board, a bare silicon chip, that is usually an integrated circuit, is supplied without a package. It can often be identified by having a blob of black Epoxy instead of a square package. Also used for LEDs. In LEDs, the epoxy is poured into a mold which forms part of the package.

Component An electronic device, typically a resistor, capacitor, inductor, or integrated circuit (IC), that is mounted to the circuit board and performs a specific electrical function.

Component Side The side of the circuit board on which most of the components will be located. Also called the “top side.”

Components Sourcing Component Sourcing Service is a key part of our Turnkey PCB Assembly Services. We take care of comprehensive components sourcing to improve our PCB assembly production efficiency and enable you, designers and engineers, to have more time on research and development, engineering, and design.

Computer-Aided Design (CAD) A software program with algorithms for drafting and modeling, providing a graphical representation of a printed board’s conductor layout and signal routes.

Computer-Aided Manufacturing (CAM) The use of computers to analyze and transfer an electronic design (CAD) to the manufacturing floor.

Computer-Integrated Manufacturing (CIM) Software that takes assembly data from a CAD or CAM package and, using a pre-defined factory modeling system, outputs routing of components to machine programming points and assembly and inspection documentation.

Conductive Pattern The configuration or design of the conductive material on the base laminate through which electrical energy passes. Includes conductors, lands, and through connections.

Conductor A thin conductive area on a PCB surface or internal layer usually composed of lands (to which component leads are connected) and paths (traces).

Conductor Base Width The conductor width at the plane of the surface of the base material. See Conductor Width.

Conductor Spacing The distance between adjacent edges (not centerline to centerline) of isolated conductive patterns in a conductor layer.

Conductor Thickness The thickness of the conductor includes all metallic coatings.

Conductor Width The observable width of the pertinent conductor on the PCB printed circuit board.

Conformal Coating An insulating protective coating that conforms to the configuration of the object coated and is applied on the completed board assembly.

Connector Area The portion of the circuit board that is used for providing electrical connections.

Contaminant An impurity or foreign substance whose presence on printed circuit assemblies could electrically, chemically, or galvanically corrode the system.

Controlled Impedance Controlled Impedance, or Impedance Control, is the matching of substrate material properties with trace dimensions and locations to create specific electric impedance as seen by a signal on the trace.

Coordinate Tolerance A method of tolerancing hole locations in which the tolerance is applied directly to linear and angular dimensions, usually forming a rectangular area of allowable variation.

Copper Clad A thin layer or sheet of copper foil, which is bonded to a laminate core to form the base material for printed circuits.

Copper Foil Copper Foil is the base copper thickness applied on the outer and inner layers of the multilayer PCBs.The copper foil can be pre-bonded by the CCL or FCCL manufacturer to a base material core, or it can be pressed in a multilayer board, then to make a copper conductor. The thicknesses of copper foil include 1/3oz, 1/2oz, 1oz, 1.5oz, 2oz and etc.

Copper Thieving Thieving, also known as Thieving Pad, Copper Thieving, or Copper Fill, is an outer layer only process, which means “copper squares” or “copper dots” are added to outer layers of a PCB board to create a uniform distribution of copper across the surface. Thieving is to make sure the copper plating in the holes is uniform. If the copper distribution in the artwork is not uniform, areas with little exposed copper will plate very heavy while areas with large amounts of copper, such as BGAs or connector pin fields will not plate properly. In the copper plating process, “thieving” steals some…

Core Thickness The thickness of the laminate base without copper.

Coupon See Test Coupon. Crazing is a condition existing in the base material in the form of connected white spots or “crosses” on or below the surface of the base material, reflecting the separation of fibers in the glass cloth and resin material.

Cover Layer Same as Coverlay. The outer layer(s) of insulating material is applied over the conductive pattern on the surface of a flexible and rigid-flex printed circuit board.

Coverlay A flexible circuit coverlay serves the exact same function as a solder mask that is used on a rigid printed circuit board. The difference with a flex coverlay is the needed element of flexibility and durability it provides to the flex PCB design. Coverlay consists of PI base material, adhesive, and release paper. When adding the coverlay to flex circuits, flexible PCB manufacturer will tear off the release paper, and align the remaining materials onto the FPC.

Crosshatching, also known as Crosshatched, Cross Hatch, Cross-Hatched Copper, Copper Cross Hatch, means an artwork design that relieves much of the copper shield areas by the use of a pattern. Crosshatch shielding can also cover selective conductors. Using Crosshatched Copper Pattern on flexible and rigid-flex printed circuit boards (PCBs) is a practical and realistic method for PCB manufacturers to (1) keep impedance-controlled traces at manufacturable dimensions,(2) retain the desired flexibility of the circuit board and assembly,(3) increase the combination among FCCL, PP, adhesive, copper and coverlay,(4) decrease the delamination risk, and (5) prevent the flex circuit…

CSP A Chip Scale Package or Chip-Scale Package (CSP) is a type of integrated circuit package. Originally, CSP was the acronym for chip-size packaging. Since only a few packages are chip size, the meaning of the acronym was adapted to chip-scale packaging.

CTE Coefficient of Thermal Expansion (CTE), expressed in ppm/ºC, which should be roughly matched to the expansion requirements of claddings, devices to be mounted on the surface and thermal planes buried in the interior.

Curing is The act of applying heat to a material in order to produce a bond.

Cut lines The cut line is going to be used to program the router path and it represents the board outside edge.

D code datum in  Gerber files which acts as a command to a photoplotter. A D code in a Gerber file takes the form of a number prefixed by the letter. “D20”.
Date Code Date Code is the week time of PCB manufacturing. The format can be WWYY or YYWW. Y means Year and W means Week.
De-wetting A condition that results when molten solder has coated a surface and then receded, leaving irregularly shaped mounds separated by areas covered with a thin solder film and with the base material not exposed.
Deburring Process of removing burrs after drilling.
Defect Any nonconformance to specified requirements by a unit or product.
The fidelity of reproduction of pattern edges, especially in a printed circuit relative to the original master pattern.
Delamination A separation between any of the layers of the base of the laminate or between the laminate and the metal cladding originating from or extending to the edges of a hole or edge of the board.
Delivery Format Delivery Format is the method in which you ask the PCB manufacturer to fabricate and deliver your PCB design. The PCB delivery formats we offer are Unit Delivery (single pieces PCB) Panel Delivery (panels by the customer or by Fuchuangke Technology) When asking panel delivery, please contact us whether your panelization meets our manufacturing capabilities, including Rigid PCB, HDI board, MCPCB, Flexible & Rigid-flex Circuit.
Design Rule Guidelines that determine automatic conductor routing behavior with respect to specified design parameters.
Design Rule Checking The use of a computer program to perform continuity verification of all conductor routing in accordance with appropriate design rules.
Desmear The removal of friction-melted resin and drilling debris from a hole wall.
Develop An imaging operation in which an unpolymerized (unexposed) photo-resist is dissolved or washed away to produce a copper PCB board with a photo-resist pattern for etching or plating.
Dewetting A condition that occurs when molten solder paste has coated a surface and then recedes, leaving irregularly shaped globules of solder separated by areas covered with a thin solder film, the base metal is not exposed.
DFA Design for assembly (DFA) is a process by which products are designed with the ease of PCB assembly and box assembly in mind. If a product contains fewer parts it will take less time to assemble, thereby reducing assembly costs. In addition, if the parts are provided with features that make it easier to grasp, move, orient, and insert them, this will also reduce assembly time and assembly costs. The reduction of the number of parts in an assembly has the added benefit of generally reducing the total cost of parts in the assembly. This is usually where the major cost…
Dielectric An insulating medium that occupies the region between two conductors.
Dielectric Constant The relative permittivity of a dielectric material, shorten to Dk, or Er. DK (/Er) constant determines the speed at which an electrical signal will travel in a dielectric material. Signal propagation speed is expressed relative to the speed of light in a vacuum, which is roughly 3.0x1010cm/c. The dielectric constant of a hard vacuum (space) is defined as 1.00. Higher dielectric constants will result in a slower signal propagation speed. The dielectric constant decreases slightly when frequency increases. Take ITEQ IT-180A as an example. DK=4.4@1GHZ, 4.3@2GHZ, 4.1@5GHZ, 4.1@10GHZ.
Differential Signal A method of signal transmission through two traces that always have opposite states. The signal data is the polarity difference between the traces in the printed circuit board.
Digitizing The converting of feature locations on a flat plane to a digital representation in X-Y coordinates.
Dimensional Stability
A measure of the dimensional change of a material that is caused by factors such as temperature changes, humidity changes, chemical treatment, and stress exposure.
In microelectronics, a Dual In-line Package (DIP or DIL), or Dual In-line Pin Package (DIPP) is an electronic component package with a rectangular housing and two parallel rows of electrical connecting pins. The package may be through-hole mounted to a printed circuit board (PCB) or inserted in a socket.

Double-Sided Board
A printed circuit board with conductive patterns on both sides.
Drill File (Excellon Drill File) It will have X & Y coordinates with tool sizes viewable in any text editor. It is this file that governs your finished hole sizes.
Drill Tool Description This is a text file describing drill tool number, corresponding size, quantity, and if the holes are to be plated or non-plated.
Drilling The act of forming holes (vias) in a substrate by mechanical or laser means.
Drills Printed Circuit Board Solid carbide cutting tools with four facet points and two helical flutes designed specifically for the fast removal of chips in extremely abrasive materials.
Dry Film A photo imagable material which is laminated onto a bare copper panel, it is exposed with 365 nm UV light through a negative photo tool, the exposed dry film is hardened by the UV light, the unexposed film is washed away in a developer solution of .8 percent sodium carbonate.
Dry-Film Resists Coating material specifically designed for use in the manufacture of printed circuit boards and chemically machined parts. They are suitable for all photomechanical operations and are resistant to various electroplating and etching processes.
Dry-Film Soldermask Coating material (dry-film resist) applied to the printed circuit board via a lamination process to protect the board from solder or plating.
DUT A device under test (DUT), also known as equipment under test (EUT) and unit under test (UUT), is a manufactured product undergoing testing, either at first manufacture or later during its life cycle as part of ongoing functional testing and calibration checks. This can include a test after repair to establish that the product is performing in accordance with the original product specification.

Edge Bevel A bevel operation performed on edge connectors of rigid PCB board to improve their wear and ease of installation.

Electrical Strength Electrical Strength measures a PCB material’s ability to resist electrical breakdown in the PCB’s Z direction (perpendicular to the PCB’s plane). It is expressed in volts/mil. Typical electrical strength values for PCB dielectrics are in the range of 800 V/mil to 1500 V/mil. Electrical strength is determined by subjecting the PCB material to short high voltage pulses at standard AC power frequencies.

Electrical Test The PCB manufacturing process includes a final electrical test (E-test) to verify net continuity and the absence of shorts on the bare printed circuit boards. We have two different types of testing equipment available to test the fabricated circuit boards, including Flying Probe and Fixture.

Electro Deposited (ED) Copper Electro Deposited (ED) Copper. With ED copper, there is a huge diversity of foils regarding surface roughness, treatments, grain structure, etc. As a general statement, ED copper has a vertical grain structure. The standard ED copper typically has a relatively high profile or rough surface as compared to Rolled Annealed (RA) Copper. ED copper tends to lack flexibility and does not promote good signal integrity.

Electroplating The electrodeposition of an adherent metal coating on a conductive object. The object to be plated is placed in an electrolyte and connected to one terminal of a direct current (DC) voltage source. The metal to be deposited is similarly immersed and connected to the other terminal.

Embedded Resistors, capacitors, and small chip die are embedded inside the PCB to increase density. Always called Resistor Embedded PCB, Capacitor Embedded PCB, and Chip Embedded PCB.

EMI Shielding EMI is the abbreviation of Electro Magnetic Immunity, which is the opposite of EMC (Electromagnetic Magnetic Compatibility). Radio Frequency Interface (RFI) shielding flexible circuits are designed to either keep out or keep in electromagnetic interference. EMI shielding reflects and absorbs incident radiation. The higher the attenuation of the shielding, the more effective it is at keeping in or out the undesired electromagnetic interference. EMI Shielding Film is always matt black. EMI Shielding Film For Flexible Printed Circuit FPC

ENIG Electroless Nickel under Immersion Gold finish.

Entry Material A thin layer of material composed of phenolic, aluminum foil, or paper that is placed on top of the panel prior to drilling to improve drill accuracy and prevent burrs and dents.

Epoxy A family of thermosetting resins. Epoxies form a chemical bond to many metal surfaces.

Epoxy Smear Epoxy resin that has been deposited on edges of copper in holes during drilling either as uniform coating or in scattered patches. It is undesirable because it can electrically isolate the conductive layers from the plated-through-hole interconnections.

Etch Factor The ratio of the depth of etching (PCB trace thickness) to the amount of lateral etch (undercut).

Etchback The controlled removal of all components of the base material by a chemical process acting on the sidewalls of plated-through holes to expose additional internal conductor areas.

Etching The chemical, or chemical and electrolytic, removal of unwanted portions of conductive materials.

Excellon Drill File This is a type of drill file that will be accepted.

Extra Press Cycles Extra Press Cycles always applied for multi-layer boards with blind vias and/or buried vias. A standard multi-layer PCB passes one time through the pressing cycle. When producing a multilayer circuit board with blind and/or buried vias, it can be required to pass a number of extra times through the pressing cycle. This is also called Sequential Buildup. These extra press cycles require an extra cost and lead time.

Fab Short from fabrication, the same as manufacturing and production when it comes to the printed circuit board.

Fab Notes Fab Notes, also known as Fabrication Notes, are a collection of notes that accompany PCB data files (Gerber files or some other data file) as a text file or are provided as in a drawing of the PCB itself that conveys the requirements and details.

Fabrication Drawing A drawing used to aid the construction of a printed circuit board. It shows all of the locations of the holes to be drilled, their sizes and tolerances, dimensions of the board edges, and notes on the materials and methods to be used. Called “fab drawing” for short.

FAI FAI is the abbreviation of First Article Inspection, which is a complete, independent, and documented physical and functional inspection process. The SMT first article assembly process in whole circuit board assembly is a very important step.

FCCL is the abbreviation of Flexible Copper Clad Laminate (CCL), which is an important PCB material to manufacture printed flexible circuit (FPC) and rigid-flex PCB. Flexible CCL refers to single-sided or double-sided flexible copper clad laminate made of polyimide (PI) film or polyester (PE) film as a substrate material that is insulating and thin copper foil conductor with flexibility on the surface. There are adhesive and no adhesive in-between the PI and copper. They are so-called adhesive FCCL and adhesiveness FCCL. Refer to below PCB blog to know more about adhesive FCCL and adhesiveness FCCL. Adhesives or Adhesive FCCL To Building…

FCT FCT is the abbreviation of Functional Testing, which is a crucial and final PCB Assembly Manufacturing step prior to integration of the PCB assemblies into complete systems.

Feed-Thru (Via) A plated through hole in a Printed Circuit Board that is used to provide an electrical connection between a trace on one side of the PCB 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.

Fiducial Mark Fiducial marks are drilled holes, or etched dots on a single piece PCB or PCB set (/panel) for which SMT assembly is required (provide viewing targets for the camera to locate correct position). These marks should be in diameter of approx. 1.6mm and free from solder mask. There should be 2 sets of fiducials if fine-pitch components are used.

Film Artwork A positive or negative piece of film containing a circuit, solder mask, or nomenclature pattern.

Fine Pitch Fine Pitch is used when referring to surface-mount components with a lead pitch of 25 mils or less. Also, refer to Pitch.

Finished Copper This is the weight or thickness of copper your PCB will have on its surface. We support HDI PCB and heavy copper PCB. The thinnest finished copper we can reach is 1/3oz, and the thickest copper we can reach is 10oz.

First Article A sample part or PCB assembly manufactured prior to the start of production for the purpose of ensuring that the manufacturer is capable of producing a printed circuit board,or PCB assembly that will meet specified requirements. The SMT first article can be inspected by the FAI machine in our SMT house.

Fixture A tooling device that enables interfacing a printed circuit board with a spring-contact probe test pattern. In the PCB assembly industry, fixtures can be used for programming, functional testing, and calibration.

Flux A substance used to promote or facilitate fusion such as a material used to remove oxides from surfaces to be joined by soldering or welding.

Flying Probe A testing device that uses multiple moving pins to make contact with two spots on the electrical circuit and send a signal between them, a procedure that determines whether faults exist.

FPC FPC is the abbreviation of Flexible Printed Circuit, can also be written as a flexible circuit, flexible PCB, flexible board, flex PCB, flex circuit, flex board, which is a printed circuit board made of thin, flexible material, like polyimide (PI)   a printed circuit made of thin, flexible material.

FR-1 A low-grade version of FR-2. Tg 130c.

FR-2 A grade of Flame-Retardant industrial laminate having a substrate of paper and a resin binder of phenolic.It is suitable for printed circuit board laminate and cheaper than woven glass fabrics such as FR-4.Tg 105 c.

FR-404 A multifunctional epoxy system that is a standard multilayer material.

FR-406 A Multifunctional Epoxy Laminate and Prepreg that has a Tg of 170 C (DSC used in applications where a higher temperature material is needed).

FR-408 A high-performance FR-4 epoxy laminate and prepreg that has a Tg of 180? (DSC). the low dielectric constant is ideal for faster signal speed and improved signal integrity. Used when layer counts begin to exceed 8 layers because its higher thermal properties minimize Z-axis expansion and the potential for barrel cracking and pad lifting in complex designs.

FR4 The UL-designated rating for a laminate composed of glass and epoxy that meets a specific standard for fire-retardance.FR-4 is the most common dielectric material used in the construction of PCBs.

Gerber A software format used by the photoplotter to describe the printed circuit board design.

Gerber Files The most common and widely accepted for PCB fabrication is Gerber files. The Gerber format is an open ASCII vector format for 2D binary images. There are 2 major generations of Gerber format: Extended Gerber, or RS-274X. This is the current Gerber format. In 2014, the graphics format was extended with the option to add meta-information to the graphics objects. Files with attributes are called X2 files; those without attributes are X1 files. Standard Gerber, or RS-274-D. This obsolete was revoked. The standard file extension is.GBR though other extensions are also used.

Glass Epoxy 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.

Glass Transition Temperature Glass Transition Temperature – Tg. The temperature at which an amorphous polymer (or the amorphous regions in a partially crystalline polymer) changes from a hard and relatively brittle condition to a viscous or rubbery condition. When this transition occurs, many physical properties undergo significant changes. Some of those properties are hardness, brittleness, coefficient of thermal expansion, and specific heat. Please also refer to High Tg PCB.

Gold Finger A gold-plated terminal of a card-edge connector PCB. The gold on fingers can be immersion gold or hard gold upon the actual requirements of customers.

Gold Fingers (Linear Inches) We can plate your edge connectors with Gold. (Approx. Ni / Min. 30 Au). The input here needs to be the distance between the outside edges of the outermost tabs.

Golden Board Golden Board is the success PCB assembly passed first article inspection (FAI) and other testing, and the mass production afterwards should use the same components & materials, assembly setup, work situation, and the quality also should be the same as this Golden Board.

Ground Plane A conductor layer, or portion of a conductor layer, used as a common reference point for circuit returns, shielding, or heat sinking.

HAL Also known as HASL, which is the process of putting solder on exposed copper of the circuit board. Approx. 60/40 Tin/Lead mix is used.

Half-Hoes PCB The higher level of plated edge is called half-hole technology for printed circuit boards, also named as Castellations PCB or Castellated-Hole PCB, which rows of holes are routed alongside the boundaries of a PCB

Halogen-Free According to JPCA-ES-01-2003 standards, Halogen-Free PCB material must be with Cl and Br not more than 0.09% (weight percentage) in the materials.

HASL HASL is the abbreviation of Hot Air Solder Leveling. A method of coating exposed copper with solder by inserting a panel into a bath of molten solder then passing the panel rapidly past jets of hot air.

HDI HDI is the abbreviation of High Density Interconnect. Ultra fine-geometry multi-layer PCB constructed with conductive micro-via connections. These boards also usually include buried and/or blind vias and are made by sequential lamination.

HDI PCB HDI PCBs represent one of the fastest growing segments of the printed circuit board market, which contributes to the high demand in the latest technologies available to increase the functionality of PCBs using the same or less amount of area.

Heavy Copper When the internal or external layers of copper weight of a PCB are 2oz, 2.5oz, 3oz or more, we treat them as heavy copper PCBs. With heavy copper traces, the PCB board can pass through high power, voltage and current.

Hold-Down Tabs Hold-Down Tabs, or Hold-Down Copper Pads, are extensions of the copper pad and are used to help keep the pad during soldering processes both in flexible circuit assembly and rework. Stress from bending/flexing can cause issues with the copper pads maintaining adhesion to the base material. The addition of copper extending under the coverlay will help maintain the adhesion of the pads. Whenever possible, design pads larger than the access holes. If space is critical, add hold-down tabs. Hold-down tabs are especially important for single-layer circuits, because a single-layer circuit does not have the added strength of plated through- holes….

Hole Breakout A condition in which a hole is partially surrounded by the land.

Hole Density The hole density stands for the number of holes per dm² board surface. This number is usually around 600 holes/dm² for a standard double-sided PCB. However smaller component size and denser circuits on ever smaller board surfaces have driven upon the hole density. This density is linked to the costing factor for the drilling of the PCB. The more holes that need to be drilled the longer the board stays on the drilling machine and more tools (drill bits) need to be used. As long as the hole density does not exceed 1,000 holes/dm², this factor will not affect the…

Hole Pattern The arrangement of all holes in a printed board with respect to a reference point.

Hole Void A void in the metallic deposit of a plated-through hole exposing the PCB base material.

ICT ICT is the abbreviation of In-Circuit Testing, is an example of white box testing where an electrical probe tests a populated printed circuit board (PCB), checking for shorts, opens, resistance, capacitance, and other basic quantities which will show whether the assembly was correctly fabricated.

IEEE The Institute of Electrical and Electronics Engineers (IEEE) is a professional association for electronic engineering and electrical engineering (and associated disciplines) in United States. It was formed in 1963 from the amalgamation of the American Institute of Electrical Engineers and the Institute of Radio Engineers. Due to its expansion of scope into so many related fields, it is simply referred to by the letters I-E-E-E (pronounced Eye-triple-E), except on legal business documents. As of 2018, it is the world’s largest association of technical professionals with more than 423,000 members in over 160 countries around the world. Its objectives are the…

Imaging The process by which panelization data are transferred to the photo plotter, which in turn uses light to transfer a negative image circuitry pattern onto the panel.

Impedance The total passive opposition offered to the flow of electric current. This term is generally used to describe high-frequency circuit boards.

Inner-layers The internal layers of laminate and metal foil within a multi-layer board. Also known as Internal Signal Layers.

Insulation Resistance The electrical resistance of an insulating material that is determined under specific conditions between any pair of contacts, conductors, or grounding devices in various combinations.

Intermetallic Compounds (IMC) When the molten solder paste (alloy) makes contact with the PCB finish or components lead finish, a small amount of Sn in the solder combines with the finish metal or the base copper to form a metallurgical compound.

IPC IPC, stands for Association Connecting Electronics Industries, and it is the abbreviation of its initial name “Institute of Printed Circuits” in the fall of 1957. IPC is the only trade association that brings together all of the players in this industry: designer, PCB manufacturers, PCB assembly companies, suppliers, and original equipment manufacturers.

JTAG JTAG (named after the Joint Test Action Group which codified it) is an industry standard for verifying designs and testing printed circuit boards after manufacturing and assembly. In 1990, the Institute of Electrical and Electronics Engineers (IEEE) codified the results of the effort in IEEE Standard 1149.1-1990, entitled Standard Test Access Port and Boundary-Scan Architecture.

Kapton Kapton, is a polyimide (PI) film developed by Dupont in the late 1960s that remains stable across a wide range of temperature, from -269 to +400 celsius degrees. In flexible circuit manufacturing industry, people always treat Kapton as polyimide. Polyimide is always used as the dielectrict material in flexible copper clad laminate (FCCL), coverlay and stiffener for FPC and rigid-flex PCB. Check to know more Adhesiveless or Adhesive FCCL To Building Your Flexible Circuit?

Known Good Board (KGB) A board or assembly that is verified to be free of defects. Also known as a Golden Board.

Laminate The plastic material usually reinforced by glass or paper that supports the copper cladding from which circuit traces are created.

Laminate Thickness Thickness of the metal-clad base material, single- or double-sided, prior to any subsequent processing.

Laminate Void An absence of epoxy resin in any cross-sectional area that should normally contain epoxy resin.

Laminating Press Laminating Press is the process by which the CCL core(s) of a printed circuit board (PCB) are melted together through heat and pressure with copper layers and prepreg layers to manufacture multilayer printed circuit boards.

Land The portion of the conductive pattern on printed circuits designated for the mounting or attachment of components. Also known as a pad.

Landless Hole A plated-through hole without land(s). Also referred to as padless plated holes.

Laser Photo Plotter A photo plotter which uses a laser to expose film to create the image.

Lay-Up (1) The technique of registering and stacking layers of materials (laminate and pre-preg) for a multilayer PCB in preparation for the laminating cycle. (2) The laying out of repeat images on film to create multiple groups of printed circuit boards. (3) The laying out of multiple layers in preparation for multilayer lamination.

Layer Sequence Please include a layer sequence or pass through marks so that we are able to build your order with the correct stack up.

Layer-to-Layer Spacing The thickness of dielectric material between adjacent layers or conductive circuitry in a multilayer printed circuit board.

Layers The plains of copper connected by the plated through holes. On board text such as company name, logo, or part number that is correct reading on the top layer will insure the layer are placed correctly.

Legend A format of lettering or symbols on the printed circuit board: e.g. part number, serial number, footprint, and patterns. See Nomenclature or Silk Screen.

LGA The Land Grid Array (LGA) is a packaging technology with a rectangular grid of contacts on the underside of a package. The contacts are to be connected to a grid of contacts on the PCB. Not all rows and columns of the grid need to be used. The contacts can either be made by using an LGA socket, or by using solder paste. LGA Land Grid Array

See Conductor.

Loss Tangent
Tangent is a measure of how much of the power of a signal is lost as it passes along a transmission line on a dielectric material.

Lot A quantity of circuit boards that share a common design.

Lot Code Some Customers require a manufacturer’s lot code to be placed on the board for future tracking purposes. Your order form is how you select it. A drawing can specify the location, what layer and if it is to be in copper, mask opening, or silkscreen.

LPI LPI is the abbreviation of Liquid Photo-imageable Solder-mask, a mask sprayed on using photographic imaging techniques to control deposition.

Major Defect A defect that is likely to result in failure of a unit or product by materially reducing its usability for its intended purpose.

Mask A material applied to enable selective etching, plating, or the application of solder to a PCB. Also called soldermask or resist.

Measling Discrete white spots or crosses below the surface of the base laminate that reflect a separation of fibers in the glass cloth at the weave intersection.

Metal Foil The plane of conductive material of a printed board from which circuits are formed. Metal foil is generally copper and is provided in sheets or rolls.

Metallurgical Laboratory (1) Refers to the process(es) of inspecting internal board quality characteristics through the use of microsections. (2) Used interchangeably with microsection.

Micro BGA µBGA, or Micro BGA, is the abbreviation of micro ball grid array.

Micro Circuits Very fine lines 2mil and less and small micro vias 3 mil and less.

Micro-section The preparation of a specimen of a material, or materials, that is to be used in metallographic examination. This usually consists of cutting out a cross-section followed by encapsulation, polishing, etching, and staining.

Micro-Via Micro-Via, also called Microvia, usually defined as a conductive via used to connect adjent layers of a multilayer PCB, typically less than 6mil in diameter, including 3mil, 4mil and 5mil. May be formed by laser ablation, plasma etching, or photo processing.

Microvia (Build-Up Via)
A blind or subsequently buried hole that is ?0.15 mm [0.00591 in] in diameter having a pad diameter that is ?0.35 mm [0.0138 in] and formed either through laser or mechanical drilling, wet/dry etching, photo imaging or conductive ink-formation followed by a plating operation.

Mil One-thousandth of an inch 0.001:” (0.0254 mm). [From abbreviation of milli-inch].

Minimum Annular Ring The minimum metal width, at the narrowest point, between the circumference of the hole and the outer circumference of the land. This measurement is made to the drilled hole on internal layers of multilayer printed circuit boards and to the edge of the plating on outside layers of multilayer boards and double-sided boards.

Minimum Traces & Spacing Traces are the “Wires” of the Printed Circuit Board (also known as tracks). Spaces are the distances between traces, the distances between pads, or the distances between a pad and a trace. How wide is the smallest trace (line, track, wire), or space between traces or pads, Whichever is less of the two governs the order form selection.

Minor Defect A defect that is not likely to result in the failure of a unit of product or that does not reduce the usability for its intended purpose.

Multi-Layer Board Multi-layer Printed Circuit Boards (PCBs) consists of a number (four or more) of separate conducting circuit planes separated by insulating materials and bonded together into relatively thin homogeneous constructions with internal and external connections to each level of the circuitry as needed.

Multilayer Circuit Board The general term for completely processed printed circuit configurations consisting of alternate layers of conductive patterns and insulating materials bonded together in more than two layers.

Negative An artwork master or production master in which the intended conductive pattern is transparent to light,and the areas to be free from conductive material are opaque.

Net-List 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 system for board test and in-circuit test purposes.

Netlist List of names of symbols or parts and their connection points which are logically connected in each net of a circuit. A netlist can be “captured” (extracted electronically on a computer) from a properly prepared CAE schematic.

Nomenclature Identification symbols applied to the board by means of screen printing, inkjetting, or laser processes. See Legend or Silk Screen.

Nonfunctional Land A land on internal or external layers, not connected to the conductive pattern on its layer.

NPTH NPTH is the abbreviation of Non-Plated through holes, which haven’t copper in the hole barrels.

Number of Holes This is the total number of holes in the board.

Outer-layer The top and bottom sides of any type of circuit board.

Outgassing Deaeration or other gaseous emission from a printed circuit board when exposed to the soldering operation or to vacuum.

Overhang Increase in printed circuit conductor width caused by plating build-up or by undercutting during etching.

Oxide A chemical treatment to inner layers prior to lamination, for the purpose of increasing the roughness of clad copper to improve laminate bond strength.

Pad See Land.

Pad Fillets Pad Fillets improve etched yield and material strength. Fillets are appropriate when the pad diameter is greater than the connecting strand width. Acute angles at the interface between conductors and pads are to be avoided by using fillets to minimize the concentration of stress at the interface. Pad Fillets in PCB Design

Pad Size The Pad Size is the actual size of a pad, which is what the pins of an SMD component rest on to be soldered. The area where artwork designs fail most to allow enough processing tolerance to meet the minimum annular ring is “pad size” calculation. The following is the mininum pad size calculation formula from MIL-STD-2118: Min Pad Size = A + 2B + 2C(when required) + D A = Max diameter of the drilled hole for internal land(s) and finished hole for external land(s). B = Min annular ring C = Max allowance for etchback (when required) D…

Panel (1) The square or rectangular base material containing one or more circuit patterns that passes successively through the production sequence and from which printed circuit boards are extracted. (2) Most people don’t understand the difference between PCB Panel and PCB Set. Set size is smaller than Panel size. A Panel can include one or a few PCB Set.

Panel Plating The electrolytic plating of the entire surface of a panel. Plating on a PCB refers to the electrochemical process by which copper is deposited onto the surface of the circuit board, and inside the plated through-holes. Copper plating in PCB fabrication serves two purposes, it increases the copper thickness of the surface pads and conductors as well as providing a robust copper connection from layer to layer through the plated through-holes.

Panelize 1. To lay up more than one (usually identical) printed circuits on a pans. Individual printed circuits on a panel need a margin between them of 0.3″. Some PCB manufacturers permit less separation. 2. Lay up multiple printed circuits (called modules) into a sub-panel so that the sub-panel can be assembled as a unit. The modules can then be separated after assembly into discrete printed circuits.

Part Number The name or number associated with your printed circuit board. We use your part number throughout the entire order process for your convenience.

Pattern The configuration of conductive and nonconductive materials on a panel or printed board. Also, the circuit configuration on related tools, drawing, and masters.

Pattern Plating The selective plating of a conductive pattern.

PC Board PC is the abbreviation of Printed Circuit, and PC Board is also Printed Circuit Board.

PCB Assembly PCB Assembly, also called Printed Circuit Board Assembly, which is an entire process of SMT assembly and PTH assembly.

PCB Boarder The Panel Border of a customer panel is not part of your PCB circuit design, but is added as extra material around your PCB or multiple of your PCBs to form a customer panel. The panel border is usually applied to enforce the mechanical stability of the panel and to allow non functional material outside the PCB that can be used for clamping the panel during SMT assembly. See PCB Panelization, SMT Panel, Waste-tabs.

PCB Card An older name for a printed circuit board.

PCB Design PCB Design also called PCB Layout. 1. The creation of artwork for the manufacturing of bare PCBs. 2. The artwork so created. 3. A computer database used to generate such artwork as data files ( CAM files ).

PCB Loader In SMT assembly process, PCB loader is usded to transport bare PCBs to rails before solder paste printing, and this machine can save labor.

Peel Strength The force required to peel the conductor or foil from the base material. Permittivity Measure of the ability of a material to store electrical energy when exposed to an electrical field.

Photo Plotter A high-accuracy (1mil) flatbed or rotary plotter with a programmable, photo image projector assembly. It is most often used to produce actual-size master patterns for printed circuit artwork directly on dimensionally stable, high-contrast photographic film.

Photo Print The process of forming a circuit pattern image by hardening a photosensitive polymeric material by passing light through a photographic film.

Photo-Resist A light-sensitive material that is used to establish an image by exposure to light and chemical development.

Photographic Image An image in a photo mask or in an emulsion that is on a film or plate.

Photoplotting Photoplotting is an electronic optical process to scan rasterized image data on films. Sometimes refer to as laser plotting. A photoplot is a film generated by photoplotter, or referred to as artwork required for PCB fabrication.

Phototool A transparent film that contains the circuit pattern, which is represented by a series of lines of dots at a high resolution.

PI PI is the abbreviation of Polyimide, which is the insulating and mechanical support film material of FCCL (flexible copper clad laminate), and main material of flexible printed circuits (FPC). Polyimide PI base material of flexible printed circuit FPC

Pitch (1) In PCB manufacturing, Pitch is the center-to-center spacing, means the distance between the centers of adjacent features or traces on any layer of a printed circuit board. (2) In SMT assembly, Pitch of the surface mount is defined as the dimension from center to center of surface mount pads.

Plasma A highly-ionized gas containing an approximately equal number of positive ions and negative electrons. Thus, as a whole it is electrically neutral, though conductive and affected by magnetic fields.

Plated-Through Hole A hole in a circuit board that that been plated with metal (usually copper) on its sides to provide electrical connections between conductive patterns layers of a printed circuit board. Also refer to PTH.

Platen A flat plate of metal within the lamination press in between which stacks are placed during pressing.

Plating Resists Material that, when deposited on conductive areas, prevents the plating of the covered areas. Resists are available both as screened-on materials and as dry-film photopolymer resists.

Plating Void The area of absence of a specific metal from a specific cross-sectional area.

PLC A Programmable Logic Controller (PLC) or programmable controller is an industrial digital computer which has been ruggedized and adapted for the control of manufacturing processes, such as assembly lines, or robotic devices, or any activity that requires high reliability control and ease of programming and process fault diagnosis.

Plotting The mechanical converting of X-Y positional information into a visual pattern such as artwork.

Polyimide Polyimide (PI) is a polymer of imide monomers. Polyimides have been in mass production since 1955. With their high heat-resistance, polyimides enjoy diverse applications in roles demanding rugged organic materials, e.g. high temperature fuel cells, displays, and various military roles. In flexible PCB and rigid-flex PCB, polyimide plays the roles of FCCL, coverlay and stiffener. Check to know more Adhesiveless or Adhesive FCCL To Building Your Flexible Circuit?

Pregreg Sheet material (e.g. glass fabric) impregnated with a resin cured to an intermediate stage (B-stage resin), also read as PP in the stack-up.

Prepreg Prepreg (PP), or Pre-preg, a shorthand expression for Pre-Impregnated, also called B-Stage, Bonding Sheet, or simply Preg, which is composited of fiberglass fabric impregnated with resin. The resin has been partially cured but not hardened during the Prepreg coating operation. When heating the PCB stack-up in pressing process, the resin in Prepreg will flow, stick and bond the core with copper foil or other materials, like cover-lay and stiffeners. Check to know All About PCB Prepreg (PP) PCB Type Prepreg Application PCB Layer Rigid PCB Bonding CCL with copper foil Multilayer Flex Circuit with Stiffener Bonding FPC with stiffener single-sided to…

Press-Fit Contact An electrical contact that can be pressed into a hole in an insulator, printed board (with or without plated-through holes), or a metal plate. Press-fit component is another type of PTH assembly

Pressing The process by which a combination of heat and pressure are applied to a book, thereby producing fully cured laminated sheets.

Printed Board The general term for completely processed printed circuit or printed wiring configurations. It includes single, double-sided, and multi-layer boards, both rigid and flexible.

Printed Circuit A conductive pattern that comprises printed components, printed wiring, or a combination thereof, all formed in a predetermined design and intended to be attached to a common base. (In addition, this is a generic term used to describe a printed board produced by any of a number of techniques.)

Printed Circuit Board (PCB) The general term for a printed or etched circuit board. It includes single-sided, double-sided, or multilayer boards, both in rigid, rigid-flex and flexible. A printed circuit board mechanically supports and electrically connects electronic components or electrical components using conductive tracks, pads and other features etched from one or more sheet layers of copper laminated onto and/or between sheet layers of a non-conductive substrate.

Printed Wiring Board A part manufactured from rigid base material upon which completely processed printed wiring has been formed.

PSA PSA is the abbreviation of Pressure Sensitive Adhesive, which is an adhesive used to bond stiffeners to specific regions of the flex circuit. The common used PSA material to bond stiffeners onto the FPCs are 3M467 and 3M9077 transparent double-sided tape.

PSA Stiffener Bonding In Flex & Rigid-Flex PCB manufacturing, there are two stiffener attachment methods to bond stiffener to the printed circuit board. (1) Thermally Bonding with Heat and Pressure. The preferred one is to thermally bond the stiffener to the circuit with the same flexible adhesive (AD) as used to attach the coverlays under high heat and pressure, and this will result in a very strong permanent stiffener bonding. (2) Bonding only with Pressure. This is an alternative attachment method available, which is done with PSA (Pressure Sensitive Adhesive) material (e.g.: 3M /Tesa Tape, 3M467 or 3M9077) if the design prevents the use…

PTFE Woven glass materials exceptionally well controlled electrical and mechanical properties. The dielectric constant range is 2.45 to 2.65 used for RF applications working at high frequency.

PTH Plated Through-Hole is that has copper plating in the hole barrel that make an electrical connection between layers.

Pulse Plating A method of plating that uses pulses instead of a direct current.

QFN QFN is the abbreviation of Quad Flat No-Leads Package, physically and electrically connect integrated circuits to printed circuit boards. Flat no-leads, also known as micro leadframe (MLF) and SON (small-outline no leads), is a surface-mount technology, one of several package technologies that connect ICs to the surfaces of PCBs without through-holes.

Quantity Enter in the number of boards you need. If you do not know your desired quantity, enter in an approximate amount for pricing.

Readme File A text file included in the zip file, which provides necessary information needed to manufacture your order. Phone numbers or email addresses of designer or engineer contacts for this project should be included to expedite resolution of any potential manufacturing problems that could delay your order.

Reflow The melting of electrodeposited tin/lead followed by solidification. The surface has the appearance and physical characteristics of being hot-dipped.

Resin (Epoxy) Smear Resin transferred from the base material onto the surface of the conductive pattern in the wall of a drilled hole.

Resin-Starved Area A region in a printed circuit board that has an insufficient amount of resin to wet out the reinforcement completely evidenced by low gloss, dry spots, or exposed fibers.

Resist Coating material used to mask or to protect selected areas of a pattern from the action of an etchant, solder, or plating. Also called soldermask or mask.

Resistivity The ability of a material to resist the passage of electrical current through it.

Reverse Image The resist pattern on a printed circuit board enabling the exposure of conductive areas for subsequent plating.

Revision If you have the same drawing number but updated revisions, please enter it here. This will avoid any confusion for manufacturing your desired boards. Please make sure that your revision number is included with your drawings in your Readme file.

Rework Reprocessing that makes articles conform to specifications.

RF Radio frequency (RF) is the oscillation rate of an alternating electric current or voltage or of a magnetic, electric or electromagnetic field or mechanical system in the frequency range from around 20 kHz to around 300 GHz. This is roughly between the upper limit of audio frequencies and the lower limit of infrared frequencies; these are the frequencies at which energy from an oscillating current can radiate off a conductor into space as radio waves. Different sources specify different upper and lower bounds for the frequency range.

Rigid-flex Rigid-flex PCB construction combining flexible circuits and rigid multi-layers usually to provide a built-in connection or to make a three-dimension form that includes components.

Robber An exposed area generally attached to a rack used in electroplating, usually to provide a more uniform current density on plated parts. Thieves are intended to absorb the unevenly distributed current on parts, thereby assuring that the parts will receive a uniform electroplated coating. Please refer to Robber or Copper Thieving for details.

Rolled Annealed (RA) Copper Rolled Annealed (RA) Copper. RA copper has been used extensively in the flex circuits manufacturing and rigid-flex PCB fabrication industry for decades. The grain structure and smooth surface is ideal for dynamic, flexible circuitry applications. Another area of interest with rolled copper types exists in the high-frequency signals and applications. It has been proven that copper surface roughness can impact high-frequency insertion loss and a smoother copper surface is advantageous. Please check another type Electro Deposited (ED) Copper.

Rough Holes Holes with a copper burr around either the entry or exit hole and that lack a smooth barrel.

Router A machine that cuts away portions of the panel to release the board with the desired shape and size required.

Routing In PCB design, wire routing, commonly called simply routing, is a step in the design of printed circuit boards (PCBs) and integrated circuits (ICs). It builds on a preceding step, called placement, which determines the location of each active element of an IC or component on a PCB. After placement, the routing step adds wires needed to properly connect the placed components while obeying all design rules for the IC. Together, the placement and routing steps of IC design are known as place and route. In PCB Depanelizing, routing is a common PCB panel seperation method like V-grooving (V-cut), but…

Scoring A technique in which grooves are machined on opposite sides of a panel to a depth that permits individual boards to be separated from the panel after component assembly.

Screen Printing A process for transferring an image to a surface by forcing suitable media through a stencil screen with a squeegee.

Selective Plating A process for plating unique features with a different metal than the remaining features will have.Created by imaging,exposing,and plating selected area and then repeating the process for the remainder of the board.

Shadowing A condition occurring during etchback in which the dielectric material,in contact with the foil,is incompletely removed although acceptable etchback may have been achieved elsewhere.

Short Circuit An abnormal connection of relatively low resistance between two points of a circuit. The result is excess (often damaging) current between these points.

Silk Screen Marking ink is used to identify components during later assembly and troubleshooting processes. This can be placed on one or two sides (in yellow or white),depending on the board design and application.We can include your company logo if it is provided on the drawing specs.

Single-Sided Board A printed board with conductive pattern on one side only.

Size X & Y All dimensions are in inches. If your board is in metric, please convert to inches.

Slots / Cutouts Slots are internal cutouts usually long and thin. By selecting Slots we will add up to 5 slots per board.If your design has more than 5 slots,additional costs may be needed.

Smallest Hole This is the final size of the hole.We will select a drill larger than the specified hole size to allow for plating thickness.

SMOBC Solder Mask Over Bare Copper (SMOBC) is a method of a printed circuit board fabrication which results in final metallization under the solder mask being copper with no protective metal, The non coated areas are coated by solder resist, exposing only the component terminal areas, this eliminates tin lead under the components .

SMT SMT is the abbreviation of Surface Mounting Technology, is a method for producing electronic PCB assembly in which the components are mounted or placed directly onto the surface of printed circuit boards. An electronic device so made is called a surface-mount device. In industry, it has largely replaced the through-hole technology construction method of fitting components with wire leads into holes in the circuit board.

SOC A System On a Chip (SOC) is an integrated circuit that integrates all components of a computer or other electronic system. These components typically include a central processing unit, memory, input/output ports and secondary storage – all on a single substrate or microchip, the size of a coin.It may contain digital,analog,mixed-signal,and often radio frequency signal processing functions,depending on the application. SOC System On a Chip (Raspberry Pi)

Solder An alloy that melts at relatively low temperatures and is used to join or seal metals with higher melting points.A metal alloy with a melting temperature below 427°C (800°F).

Solder Leveling The process by which the board is exposed to hot oil or hot air to remove any excess solder from holes and lands.

Solder Mask Coating material used to mask or to protect selected areas of a pattern from the action of an etchant, solder, or plating. Also called resist or mask.

Solder Mask Dam The solder mask bridge between solder pads on surface PCB.

Solder Paste Solder paste is the mixture of solder powders and flux deposited onto pads of a printed circuit board with a controlled volume. After reflow soldering,it provides electrical,mechnical and thermal connection between soldered components and PCB board.

Solder Paste Printer Solder paste printer is usded to deposit solder paste onto the pads of bare printed circuit boards.

Solder Resists Coatings that mask and insulate portions of a circuit pattern where solder is not desired.

Solderability Testing The evaluation of a metal to determine its ability to be wetted by solder according to 202,Method 208;MIL-STD 883,Method 2003.10; IPC-TM-650, Method 2.4.12 The Solderability test method provides optional conditions for preconditioning and soldering for the purpose of assessing the solderability of device package terminations. It provides procedures for dip & look solderability testing of through hole,axial and surface mount devices and a surface mount process simulation test for surface mount packages.Solderability testing provides a means of determining the solderability of device package terminations that are intended to be joined to another surface using SnPb or…

Soldermask Over Bare Copper The same as SMOBC.

SOP SOP is the abbreviation of Small Outline Package. A Small Outline Integrated Circuit is a surface-mounted integrated circuit package which occupies an area about 30–50% less than an equivalent dual in-line package (DIP),with a typical thickness being 70% less. They are generally available in the same pin-outs as their counterpart DIP ICs. The convention for naming the package is SOIC or SO followed by the number of pins. For example, a 14-pin 4011 would be housed in an SOIC-14 or SO-14 package.SOP Small Outline Package

Squeeze Squeeze is the critical tool used to “push” solder paste through the designated windows of the stencil.

Stack-up PCB or Board buildup A PCB is defined by the PCB designer as a number of copper layers in a well define sequence. The pattern in each copper layer combined with the drill patterns and the copper plating of these drilled holes,form an electrical net that is responsible for connecting the pins of components to other pins of other components.

Stacked Vias Micro vias in HDI PCB that are stacked one upon each other. Stacked Vias in HDI PCB

Starvation Resin A deficiency of resin in base material that is apparent after lamination by the presence of weave texture,low gloss,or dry spots.

Stencil SMT stencil,also called solder paste stencil,is the tool by which the volume and placement locations of solder paste deposition is controlled.

Step-and-Repeat A method by which successive exposures to a single image are made to produce a multiple image production master.

Stiffener Stifferners are added rigidize areas of a flexible printed circuit (FPC) to strain relieve component attachment locations, provide a firm surface for mounting, or increase thickness of the circuit to correspond to the mechanical specifications (e.g. ZIF connector). Stifferner materials can be Polyimide (PI), FR4 and Stainless Steel.

Strain Relief Fillet A Strain Relief Fillet is defined as a Flexible Bead,typically epoxy based, applied to the transition line from a rigid area to a flex area. This forces the flex to bend gradually and prevents it from being bent tightly against the rigid area which could damage the part.Strain Relief Fillet in Rigid-Flex PCB IPC calls out for a min 10mil (0.254mm) height difference between the rigid area and the flex layers to allow enough space for the bead without it extending above the surface level of the rigid areas. Strain reliefs requirements are defined…

Stripping The process by which imaging material (resist) is chemically removed from a panel during PCB fabrication. The steps to image-develop-etching-stripping (ES) are: 1.Apply dry film that is photo imageable to the copper panels. 2.Image the panels using laser direct imaging. 3.Develop the dry film. All areas exposed by the laser will remain while the unexpected areas will develop off. The remaining film will act as etch barrier to prevent the conductive pattern from being etched, while exposing any unwanted copper (this is for inner layers.) 4.Etching off the exposed copper from the panel. 5.Stripping the remaining dry film so the…

Substrate A material on whose surface adhesive substance is spread for bonding or coating. Also,any material that provides a supporting surface for other materials used to support printed circuit patterns.

Subtractive Processing The method of selectively removing copper from a board to form a circuit. In this case,“subtractive” refers to the method of image transfer from a phototool or image file to the copper circuit.

Tab Routing Rather than completing the route path around the board edge, “Tabs” are left so as to leave boards attached in pallets for ease in PCB assembly.

Tab Routing with Perforation Holes Same as tab routing above with the exception that we add perforation holes along the tabs to make it easier to break apart your boards at a later date. We recommend tab routing if you plan to have your boards assembled.

Target Land (Via Bottom Land) Target Land (Via Bottom Land) Land on which a microvia ends.

Td Thermal Decomposition Temperature (Td): This property varies greatly with the chemical composition of materials, from the mid 300ºC range for many epoxy systems to over 400ºC for some polyimides. Td is the temperature at which a material begins to degrade thermally. Some data sheets will list a Td as the temperature at which a material has lost 5% of its original weight due to decomposition. A better indicator of performance would be the onset temperature, at which significant weight loss begins to occur.By the time a material, has lost 5% of its weight to decomposition it may well be…

Tented Via A via with solder mask completely covering both its pad and its plated-thru hole. This completely insulates the via from foreign objects,thus protecting against accidental shorts,but it also renders the via unusable as a test point.Sometimes vias are tented on the top side of the board and left uncovered on the bottom side to permit probing from that side only with a test fixture,unbroken and broken Tented Via with solder mask

Test Coupon A portion of a printed board or of a panel containing printed coupons used to determine the acceptability of such a PCB board.

Tg Glass Transition Temperature (Tg). The point at which rising temperatures cause the solid base laminate to start to exhibit soft, plastic-like symptoms. This is expressed in degrees Celsius (°C). Check to know more High Tg PCB.

Thief An extra cathode placed as to divert to itself some of the current from portions of the board which otherwise would receive too high a current density. Please refer to Robber or Copper Thieving for details.

Tooling Holes The general term for holes placed on a PCB or a panel of PCBs for registration and hold-down purposes during the manufacturing process. Also known as Fabrication Hole, Pilot Hole, or Manufacturing Hole. The recommended tooling holes’ diameter is 2mm (78.74mil). If want to set the PCB direction, need to add 3 fiducial marks with diameter 1.5mm (59mil). Of course, need to add fiducial openings with diameter 3mm (118mil) out of the fiducial marks. PCB Tooling Holes

Top Side The side of the circuit board on which most of the components will be located. Also called the “top side.”

Trace A common term for conductor. Also known as track.

Turnkey Service Turnkey Service includes PCB fabrication, components sourcing and PCB assembly. If require value-added service, we also can provide SPI, AOI, X-ray, ICT, and FCT service.

Twist A laminate defect in which deviation from planarity results in a twisted arc.

Typical Relow Profile The reflow of solder is achieved in a furnace with predetermined thermal profiles.The different stages are:Pre-heat Zone Soak (dry out) Zone Reflow Zone Cooling The temperature of the reflow oven can be measured by profile equipment. It is usually used to measure the temperature between the PCB pads and SMD chip component pads.

UL Underwriters Laboratories, Inc., an independent product safety testing and certification organization.

Underwriters Symbol A logotype denoting that a product has been recognized (accepted) by Underwriters Laboratories Inc. (UL).

UV Curing Polymerizing, hardening, or cross linking a low molecular weight resinous material in a wet coating ink using ultra violet light as an energy source.

V-Cut V-cut,or V-cutting also named as V-grooving, please refer to V-Scoring for details.

V-Grooving V-grooving also named as V-cut (or V-cutting), please refer to V-Scoring for details.

V-Scoring V-Scoring also named as V-grooving or V-cut (or V-cutting). V-Scoring is to cut a “V” groove on the top and bottom of a bare PCB while leaving a minimum amount of material in place to hold the boards together.Rather than completing a route path around the board edge,V-scoring is a process to allow breaking boards apart after PCB assembly.This is another way to panelize the boards (see Tab Routing).

Via A plated through-hole that is used as an interlayer connection but does not have component lead or other reinforcing material inserted in it.

Via-in-Pad Via-in-Pad means via is placed entirely within the pad of a surface mount component.Via-in-pad technique requires both additional process steps and extra materials. Added costs are found in both the extra materials used,including epoxy or metal based via fill materials and copper cap plating processes,as well as added process steps like vacuum via fill,curing,planarization and secondary plating operations.

Void The absence of any substances in a localized area.

Waste-Tabs  Waste-tabs,also called Technique Tabs,should be added to the PCB Panel.The waste-tabs with 5-14mm will increase the PCB cost of the Panel, but sometimes reduce the SMT assembly cost.See PCB Boarder.

Wave Soldering  A process wherein assembled printed boards are brought in contact with a continuously flowing and circulating mass of solder,typically in a bath.

Wetting  Wetting means the ability of the molten solder paste (alloy) to adhere to PCB pad surfaces being soldered.

Wicking  Migration of copper salts into the glass fibers of the insulating material.

WIP  An acronym for work in progress.

Z-Direction Expansion  Ideally the Z-direction expansion should match that of the copper in the plated through holes (about 17 ppm/ºC) to avoid damaging the plated copper during thermal excursions resulting from process steps such as solder reflow. Most standard materials have CTE’s of 50-60 ppm/ºC below the Tg, and roughly 4x higher above the Tg.High Tg materials such as polyimide have less overall Z-direction expansion (about 1.1% from 50ºC to 250ºC) than typical epoxy systems (with about 3 to 4% from 50ºC to 250ºC) due to their higher Tg.

Zero Defects Sampling A statistical-based attribute sampling plan (C = O) where a given sample of parts is inspected and any defects found are cause for rejection of the entire lot.

ZIF Zero Insertion Force (ZIF) is a type of IC socket or electrical connector that requires very little force for insertion. With a ZIF socket, before the IC is inserted, a lever or slider on the side of the socket is moved, pushing all the sprung contacts apart so that the IC can be inserted with very little force.

Zip File All files needed for the processing of your order must be compressed in a zip file. Due to a large number of orders received, we are not able to accept individual layer files sent to us.

Circuit Board Fabrication and PCB Assembly Turnkey Services

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