Printed Circuit Boards (PCB) Glossary
A
Active Component:A part that relies on an external source of power for activation of its inputs. Examples of active components include rectifiers controlled by silicon and transistors, as well as valves for instance. Additionally, active components may be described as ones that aren’t comprised of resistor, capacitor, or inductor.
activating The Activating chemical treatment process used to increase the receptivity to non-conductive materials. Conductive material is placed on the base material, either clad or unclad. This process is also referred to as catalyzing, seeding and making.
Additive Method: The title suggests, this method is used in multi-layer boards to plating through (non-conductive) holes in order to form vias.
Ain:AIN is the name of aluminum nitride that is a mixture made up of nitrogen and aluminum.
Substrate AIN:This is an aluminum Nitride substrate.
Alumina:Alumina is an example of a ceramic used as a material in a thin film circuits, or an as an insulator for electron tubes. Alumina can stand up to the low loss of dielectric across a broad range of frequencies, as in high temperatures.
Ambient: It describes a ambient environment which comes into contact with the device or the system being considered.
Analog Circuit:In this circuit output signals change in accordance with the constant result of input.
Annular Ring: Annular ring an annular pad constructed out of conductor material that is surrounded by the hole.
Anode: It is a positive component within the tank for plating. It’s connected to the potential positive. Anodes can be used to accelerate the motion of metal ions toward the the circuit board which is being coated.
Anti-Solder ball:It is an important technique used in Surface Mount Technology (SMT) to control how much tin which goes across the stencil.
Anti-Tarnish:This is a process chemically performed post dip to decrease the copper circuit’s oxidation.
Every layer that is inside a via hole: abbreviated as ALIVH This technology is utilized to create multilayer PCBs with no core. When PCBs are constructed that use ALIVH an connections are made between layers via soldering instead of vias or a core boards. This process is utilized to create BUM PCBs that have interconnecting layers inside with extremely dense density.
Aperture The Aperture is an index shape that has specific size and dimensions of length. The index of an aperture is generally the D code. This can be used as an element of base when drawing geometric components in a film.
Aperture Wheel:A Metal disk element with screw holes and cutouts, with brackets located near rims of the disk for aperture fixing.
information on aperture:The text file featuring the size and shape of every board component. Also known as D Code List.
Aperture list/Aperture tables: It is an ASCII text file that contains details about the apertures utilized by a photographer for single photoplot. This list contains the dimensions and the shape of D codes.
Acceptance Quality Level (AQL): AQL is the highest permissible and acceptable level of defect within a batch. The most common reason for this is the use of statistically-derived samples for parts.
array: The word “array” is used to describe the collection of circuits which are organized in a particular arrangement.
Array Up:These are PCBs that can be used individually within the array configuration.
The X Dimension of an Array: The largest dimension of the array along the X axis including border or rails, is referred to as an array with X dimensions. It’s determined in inch.
array Y dimension: The most extreme measurements along the Y-axis is referred to as array Dimension Y. This is inclusive of borders and rails that are expressed in inches.
Artwork: It is the name given to the image plotted on film with a 1:1 pattern and used for the creation of Diazo production master. Diazo Production Master.
artwork master: This photo is an representation of the PCB’s design printed on film. It can be used to create the printed circuit board.
AS9100:It is a quality-management system that integrates requirements from industry and ISO-9001:2008 standards. The system was developed specifically to serve the aviation, defense, as well as aerospace industry.
ASCII: The ASCII refers to American Standard Code for Information Interchange. It is also known in the form of “asskey”. The character sets can be found on the majority of contemporary computer systems. US ASCII utilizes the lower 7 bits to communicate the space code, control codes punctuation marks, space numbers and also unaccented numbers such as a-z and A-Z. But, newer codes include more bits and are in RS 274x format that allows for the definition of objects.
ASCII Text: The ASCII Text is a subset of the US-ASCII. The subset is not officially recognized and includes characters, numbers punctuation, alphabets that are not accented, such as a-z and A-Z. The subset does not contain any controls codes.
Aspect Ratio: The Aspect Ratio represents the ratio between the diameter of the smallest hole diameter to the thickness of the circuit board.
AssemblyL A process for connecting and arranging components on a PCBs, or the procedure of placing components on PCBs to form one unit is referred to as assembly.
Assembly Drawing: The Assembly Drawing is a diagram that shows the location of component components and their designations on the printed circuit board.
Assembly House: It is a place for the production of PCBs. In general, assemblers and contract makers use the word to highlight their abilities.
ASTM: The ASTM is the acronym for American Society of Testing and Materials.
The ATE: This is a reference to the Automatic Test Equipment (Same as DUT). The ATE automates testing and analyzing the functional parameters in order to assess the performance in electronic gadgets.
Automatic Component Placing:Automated equipment is employed to position components over PCB. A machine for component placement with high-speed known as a chip shooter is employed to place smaller and smaller pin count. Complex components with high pin counts are positioned using high-quality machines.
Auto Router: is an automated router, or a program on a computer that can be used to create or track the trace lines within a design.
AutoCAD: Computer-aided commercial program that assists PCB designers create accurate 3D or 2D designs. It is typically utilized to design silicon chips packaging and also by RF design.
Automatic optical inspection (AOI): This is the most basic form of laser/video inspection on pads as well as traces of the inner layers of the copper cores. It uses a camera to check the position of copper in shape, size, and form. This technique is employed to identify traces that are not closed as well as missing features, shorts or features.
Automatic X-Ray Component/Pin Examination: The inspection tools employs X-ray images for checking beneath components and inside joints to check the integrity of soldering.
AWG: This is the acronym for American Wire Gauge. An PCB designer must know the diameters of wire gauges in order to create E-pads. The AWG was before known in The Brown and Sharpe (B+S) Gauge and was utilized to design wires. It is always constructed so that the following larger diameter is an area of 26% larger cross-sectional.
B
BareBoard: It is an unfinished printed circuitboard without attached components. Also known as BBT.
Back Drilling: The method of eliminating the non-useful via stubs drilling a hole either on both sides of a PCB, after plating. Back drilling is typically done for high speed PCBs, to minimize the parasitic effect of the stubs that are part of via.
Ball Grid Ball Grid (BGA): A chip package made up of internal die terminals which form an array grid-like. The terminals in the array are connected with solder bumps which form the electrical connections outside of the box. There are numerous advantages of the BGA package, for example its small size, the lead that is not damaged, as well as a longer shelf life.
Base: The electron electrode of the transistor which is responsible for controlling the holes or electron motions through an electric field. The base will always be in alignment with the grid of control in the electron tube.
Basis Copper: It comprises a small piece of copper foil that is lining the copper-clad PCB. It can be found on one side of the PCB, or inside layers.
Base Laminate: This is the substrate that is the basis on which the pattern for conductive is created. The material used for the base layer can be either rigid or flexible.
Beam Lead: A metal beam is put on the surface of the die in the process of processing wafers during the assembly of PCBs. In the event that a single die is removed from the PCB, the cantilevered beam extends out from the side of the chip. The protrusion serves to join the interconnecting pads onto the substrate of the circuit and eliminates the requirement for separate interconnections.
Barrel: It can be described as a cylindrical created by plating a hole. The the walls of a hole drilled are then plated in order to create an elongated barrel.
Base Material: The kind of material that is insulating upon which the conductive pattern forms is termed as the “base material. The material could be rigid, flexible or even a combination of both. The base material could include an insulated metal sheet or dielectric.
Thickness of the Base Material: The base material thickness determines the amount of base material, excluding any material that is on the surface, or a metal foil.
Bed of Nails: The pattern is composed of an holder as well as a frame. The holder is comprised of a row of spring-loaded pins that create electrical contact with the test object.
Bevel: The bevel is an inclined edge on the PCB.
The Bill of Materials (BOM): It is an inventory of the components that must be added to the printing circuit board assembly. The PCB’s BOM will include reference labels that will be used to identify the components as well as descriptions that identify each component. A BOM may be utilized in conjunction along with an assembly drawing as well as for placing orders on components.
Blister: A small and painful swelling which occurs between layers of a laminated base materials is known as a the blister. It can also happen between conductive foils or a base materials. The term “blowout” refers to a kind of delamination.
Blind Via: A blind via is a type of surface hole that conducts electrical energy in addition to connecting two layers of an external and an internal layer on a board. The term “blind via” is commonly used to describe PCBs with multiple layers.
Board: The term HTML0 is a synonym for printed circuit boards. Additionally, it can be utilized to refer to an CAD database that shows the layout of printed circuit boards.
Board House: It’s the name of a printed circuit boards from a vendor. Same as Assembly House.
Thickness of the Board: The thickness of the board is the total thickness of the base material, as well as the conductive material that is deposited on the substrate. PCBs are made with any thickness. But, 0.8mm, 1.6mm, 2.4 and 3.2mm are typical ones.
Body It is the part of a component electronic which is not comprised of pins or leads.
Book: The Prepegflies come in particular numbers. These are put together on the inner layer’s cores as they prepare for curing in the lamination process.
Bond Strength: It is described as the force per unit area required for the separation of two layers which are adjacent on the printed circuit board. The force used is perpendicular for the separation.
Boundary Scan Test:These are edge connector testing systems that utilize IEEE 1149 standards for describing testing capabilities that can be integrated into certain parts.
Bow: Bow is the term used to describe a deviation from the flatness of a surface that’s characterized by a spherical, or cylindrical curvature.
Border Zone Border Area:The outer region in the basis material which extends beyond the finished product which it is included within is known as a border.
The bottom SMD pads: A quantity SMD Pads located at the lower end.
B Stage: A middle stage of the PCB assembly when a thermosetting material liquefies upon heating, and then expands. But, it doesn’t completely dissolve or melt because of the presence of liquids in the vicinity.
B Stage Material: It’s an impregnated resin sheet which is then cured to form the intermediate stage. The term is often used as Prepeg.
B Stage Resin: The stage resin is a thermosetting resin which is utilized during the intermediate curing stage.
Buried via: This phrase refers to via that connects layers. The buried via is not visible on either side of the board. Additionally, it does not connect layers on the outside.
Buildtime: Each company has a specific build times. It usually begins the next day of business after getting the order, unless an hold is triggered.
Burr: A groove that forms a border within the surface of copper. In general, a burr gets made after drilling.
C
Cable:
A conductive wire designed to transmit electrical currents or thermal energy across electronic components and power distribution systems.
Self-Test Circuitry:
A diagnostic protocol using external hardware interfaces to validate device functionality and electrical performance.
CAD (Computer-Aided Design):
A digital platform enabling PCB engineers to visualize circuit prototypes on interactive displays and generate schematic blueprints.
CAD/CAM Integration:
A unified workflow combining design software with automated manufacturing protocols to streamline PCB production pipelines.
CAE (Computer-Aided Engineering):
A suite of simulation tools for PCB development, including thermal analysis modules and signal integrity validators.
CAF (Conductive Anodic Filament):
A failure mechanism where metallic ions migrate between conductors under humidity and DC voltage, forming conductive pathways that induce short circuits.
CAM (Computer-Aided Manufacturing):
An automated production system driven by programmed instructions, though critical parameters like toolpath optimization require manual oversight.
CAM Files:
Manufacturing datasets including:
Gerber Files: Direct photoplotters for circuit layer imaging
NC Drill Files: Guide precision drilling machines
Assembly Drawings: Specify component placements in standardized formats.
Capacitance:
The ability of a conductor-dielectric system to store electrical charge under voltage differentials, quantified in farads (F).
Carbon Mask:
A heat-cured conductive ink containing carbon particles and epoxy resin, applied to PCB contact points for enhanced durability in high-use interfaces (e.g., keypad circuits).
Card-Edge Connector:
A gold-plated contact array integrated along PCB edges, enabling secure board-to-board interconnects in industrial control systems.
Catalyst:
A chemical additive that accelerates polymerization reactions between resins and hardeners during PCB material curing.
Ceramic Substrate PCB:
Circuit boards fabricated from Al₂O₃ or AlN ceramics, offering exceptional thermal dissipation, electrical insulation, and solder joint reliability.
Characteristic Impedance:
The combined effect of trace geometry and dielectric properties on signal propagation, measured in ohms (Ω).
Chip-on-Board (COB):
A direct-attach method where bare semiconductor dies are bonded to PCBs using conductive adhesives, bypassing traditional packaging stages.
Chip Scale Package
A semiconductor packaging technology where the total enclosure size remains ≤20% of the silicon die dimensions (e.g., Micro-BGA configurations common in wearable devices).
Circuit:
A network of interconnected electronic components designed to execute specific electrical operations like signal processing or power distribution.
Circuit Board:
Abbreviated term for Printed Circuit Board (PCB) – the foundational platform for mounting and connecting electronic components.
Circuitry Layer:
Conductive pathways within multilayer PCBs containing power planes, ground planes, and signal traces.
Clad Copper:
Copper elements on PCBs where text identifiers like serial numbers are etched directly into the copper layer rather than silkscreen.
Clearances:
Safety margins between through-holes and internal planes (typically 0.025″ larger than drilled holes) preventing electrical shorts during thermal expansion.
Clearance Hole:
A concentric opening in conductive layers exceeding base material hole diameter to ensure isolation from surrounding copper.
CNC (Computer Numerical Control):
Automated manufacturing systems converting digital designs into precise mechanical actions via programmed code.
Coating:
Thin-film deposits (conductive/metallic or insulating/polymer) applied to substrates for enhanced functionality or protection.
Coefficient of Thermal Expansion (CTE):
Material deformation rate per temperature change, measured in ppm/°C (e.g., FR-4 substrates show 14-17 ppm/°C CTE).
Component:
Any physical device soldered to PCBs – resistors, ICs, connectors, etc. – enabling circuit functionality.
Component Hole:
Plated through-holes facilitating electrical connections between component leads and PCB traces.
Component Side:
Primary surface (typically Layer 1) where most active components mount, with orientation markers for assembly alignment.
Conductive Pattern:
Copper tracings defining electrical pathways – includes pads for component attachment and thermal relief structures.
Conductor Spacing:
Minimum visible gap between isolated copper features (edge-to-edge measurement, excluding centerline calculations).
Continuity:
Uninterrupted current flow through conductive paths verified via continuity testing during quality control.
Conformal Coating:
Dielectric protective layer (acrylic/silicone/urethane) applied post-assembly to prevent environmental damage.
Connectivity:
CAD software functionality ensuring schematic-defined component relationships translate accurately to PCB layouts.
Connector:
Modular interface components (D-subminiature, USB headers, etc.) enabling board-to-cable or board-to-board linkages.
Connector Area:
Dedicated PCB zones with specific pad arrangements and mechanical reinforcements for reliable connector mounting.
Contact Angle:
Wettability metric (measured in degrees) indicating bonding effectiveness between solder and metal surfaces.
Copper Foil Weight:
Base copper thickness specification (e.g., 1 oz/ft² = 35µm) determining current-carrying capacity and impedance.
Control Code:
Non-printable ASCII characters (e.g., carriage returns) regulating equipment behavior in manufacturing protocols.
Core Thickness:
Dielectric layer measurement excluding copper cladding – critical for impedance control in high-speed designs.
Corrosive Flux:
Aggressive cleaning agents containing halides/acids requiring post-soldering removal to prevent copper oxidation.
Cosmetic Defect:
Surface irregularities (minor discolorations/scratches) not impacting electrical performance but requiring visual inspection.
Countersink Holes:
Conical recesses accommodating screw heads for secure PCB mounting in chassis/enclosure applications.
Coverlay:
Insulating outer layers (often polyimide) protecting flexible circuits while maintaining bend durability.
Crosshatching:
A thermal management technique where conductive planes are strategically divided by grid-like voids to prevent board warping during high-temperature operations.
C-Stage:
The final cured state of epoxy resins, achieving complete cross-linking for optimal chemical resistance and dimensional stability in high-frequency circuits.
Curing:
A polymerization process converting liquid thermoset epoxy resins into solid polymers through controlled heat exposure (typically 120-180°C),
resulting in permanent molecular restructuring.
Curing Time:
Duration required for epoxy hardening, inversely proportional to temperature – e.g., 60 minutes at 150°C vs 30 minutes at 180°C in industrial curing ovens.
Cutlines:
Laser-etched reference markers guiding CNC routers to achieve ±0.1mm precision when trimming PCB panels to final dimensions.
Current Carrying Capacity:
A conductor’s maximum sustainable current (measured in amps) before exceeding safe temperature thresholds, determined by:
Copper weight (1oz vs 2oz)
Ambient airflow conditions
Trace width/spacing ratios.
Cutouts
Machined recesses serving multiple functions:
Thermal zones for heatsink mounting
High-voltage isolation between circuits
Mechanical anchors for board-to-chassis fastening.
D
D Code: In Gerber files, a D code represents a command for a photo plotter. It is formatted as a number preceded by the letter “D20.”
Database: A structured collection of interconnected data items stored in one place. Databases can support multiple applications simultaneously.
Datum or Datum Reference: A predefined point, line, or plane used as a reference to position layers or patterns during manufacturing or inspection.
Deburring: The process of removing excess copper material left around holes after drilling.
Defect: Any deviation from the standard characteristics of a component or product. Defects can be classified as major or minor.
Definition: The precision of pattern edges on a printed circuit board, measured against the master pattern.
Delamination: A separation between layers of the base material, conductive foil, or laminate. It generally refers to any planar separation on a PCB.
Design Rule Checking (DRC): A computer-aided process that verifies the continuity of conductor routings based on predefined design rules.
Desmear: The removal of melted resin and debris from hole walls, often caused during drilling.
Destructive Testing: A testing method where a portion of a circuit panel is sectioned and examined under a microscope. Typically performed on test coupons rather than functional PCB parts.
Develop: An imaging process where photo-resist is dissolved to create a copper board with a pattern for plating or etching.
Dewetting: A condition where molten solder recedes from a coated surface, leaving irregular solder globules. It is characterized by a thin solder film covering the surface without exposing the base material.
DFSM: Abbreviation for Dry Film Solder Mask.
DICY: Dicyandiamide, a widely used cross-linking agent in FR-4 materials.
Die: An integrated circuit chip cut from a finished wafer.
Die Bonder: A machine used to attach IC chips to a substrate.
Die Bonding: The process of mounting an IC chip onto a substrate.
Dielectric Constant: The ratio of a material’s permittivity to that of a vacuum, also known as relative permittivity.
Differential Signal: A signal transmitted through two wires with opposite polarities, where the data is defined by the difference between the two.
Digitizing: The conversion of flat plane feature locations into digital coordinates, such as x-y values.
Dimensional Stability: A measure of how much a material’s dimensions change due to factors like humidity, temperature, stress, or aging, typically expressed in units per unit.
Dimensioned Hole: A hole on a PCB where the X-Y coordinates do not align with the stated grid.
Double-sided Board: A PCB with conductive patterns on both sides.
Double-sided Laminate: A PCB laminate with tracks on both sides, usually connected through plated through-holes (PTH).
Double-sided Component Assembly: The mounting of components on both sides of a PCB, commonly used in SMD technology.
Drills: Solid carbide cutting tools with helical flutes and faucet points, designed for chip removal in abrasive materials.
Drill Tool Inspection: A text file listing drill tool numbers, sizes, and sometimes quantities. Sizes are interpreted as plated through-hole finished sizes.
Drill File: A file containing X-Y coordinates, viewable in any text editor.
Dry Film: A photo-imagable material laminated onto a copper panel, exposed to 365nm UV light through a negative photo tool. Exposed areas harden, while non-exposed areas are washed away in a developer solution.
Dry Film Resists: Photosensitive films applied to copper foil, resistant to etching and electroplating during PCB manufacturing.
Dry Film Solder Mask: A solder mask film applied using photographic methods, offering high resolution for surface mount and fine-line designs.
E
ECL: Emitter Coupled Logic (ECL) is a high-speed digital logic technology that utilizes a differential transmitter (transistor-based) to combine and amplify signals. While it is faster than Transistor-Transistor Logic (TTL), it is more complex to implement and comes at a higher cost.
Edge Bevel: Edge beveling is a chamfering process applied to edge connectors to create a beveled edge. This enhances the ease of installation and improves the connectors’ resistance to wear.
Edge Clearance: Edge clearance is the minimum distance measured between any components or conductors and the edge of a printed circuit board.
Edge Connector: An edge connector is located on the edge of a PCB and features holes for connecting to another device or circuit board.
Edge Dip Solderability Test: This test evaluates the solderability of a PCB by dipping a specimen into molten solder and withdrawing it at a controlled rate. It is applicable to electronic components and substrates with metalized tracks.
Edge-Board Connector: Edge-board connectors facilitate reliable connections between external wiring and the edge contacts on a PCB.
Electro-deposition: Electro-deposition occurs when an electrical current is passed through a plating solution, resulting in the deposition of conductive material onto a surface.
Electronic Component: An electronic component is a fundamental part of an electronic circuit, such as an op-amp, diode, capacitor, resistor, or logic gate.
Electroless Copper: Electroless copper refers to a copper layer deposited on a PCB surface using an autocatalytic plating solution, without the need for electrical current.
Electrode Deposition: This process involves depositing conductive material from a plating solution when an electrical current is applied.
Electroless Deposition: Electroless deposition is the process of depositing metal or conductive material without using electrical current.
Electroplating: Electroplating is the process of depositing a metal coating onto a conductive object by immersing it in an electrolytic solution and applying a direct current (DC) voltage.
Electrical Object: An electrical object is a graphical element in a PCB or schematic file, such as a wire or component pin, to which electrical connections can be made.
Electrical Test: Electrical testing is performed to detect shorts or open circuits on PCBs. It is recommended for surface-mount and multilayer boards to ensure functionality.
E-pad: An E-pad, or Engineering-pad, is a surface mount pad on a PCB used for soldering wires. It is typically labeled with a silkscreen.
EMC: Electromagnetic Compatibility (EMC) refers to the ability of electronic equipment to operate effectively in its intended electromagnetic environment without causing or experiencing interference.
Emitter: The emitter is one of the terminals of a transistor, responsible for the flow of electrons and holes between the transistor’s electrodes.
EMP: Electromagnetic Pulse (EMP) is a transient electromagnetic disturbance, often caused by nuclear detonations.
End-to-End Design: End-to-end design integrates inputs and outputs with CAD/CAM/CAE software, enabling seamless transitions between design steps without manual intervention, except for menu selections or keystrokes.
ENIG: Electroless Nickel Immersion Gold (ENIG) is a PCB finishing method that uses autocatalytic nickel to ensure uniform gold attachment.
Entrapment: Entrapment refers to the trapping of flux, air, or fumes, often caused by contamination or plating issues.
Entry Material: Entry material is a thin layer of aluminum foil or composite material placed on a PCB surface to enhance drill accuracy and prevent dents or burrs.
Epoxy: Epoxy is a family of thermosetting resins that form strong chemical bonds with various metal surfaces.
Epoxy Smear: Epoxy smear, or resin smear, is a deposition of epoxy resin on the edges or surfaces of conductive inner layers, typically caused during drilling.
ESR: ESR stands for Electro-statically applied Solder resist.
Etch: Etching is the chemical process of removing copper to create a desired circuit pattern.
Etch Factor: The etch factor is the ratio of the depth of etch (conductor thickness) to the amount of undercut (lateral etch).
Etchback: Etchback is a chemical process that removes resin smear from hole sidewalls and exposes additional internal conductor surfaces.
Etching: Etching involves removing unwanted portions of resistive or conductive materials using chemicals and electrolytes.
Excellon: Excellon format is an ASCII-based format used in NC drill files, widely adopted for driving NC drill machines.
F
Fab: Fab is the abbreviated term for fabrication.
Fabrication Drawing: A fabrication drawing is a detailed blueprint essential for constructing printed circuit boards (PCBs). It includes specifics such as hole locations, sizes, tolerances, material types, methods, and board edge dimensions. Often called a fab drawing, it serves as a comprehensive guide for PCB manufacturing.
Fast Turnaround: Fast turnaround refers to the rapid production and delivery of circuit boards, often completed within days rather than weeks.
FC: FC is the shorthand for flex circuit, flexible circuitry, or flexible circuit.
Fiducial Mark: A fiducial mark is a reference point on a PCB used for precise component placement. It is created during the same process as the conductive pattern.
Files Eagle: Eagle is a viewer that allows previewing production files as interpreted by plotting software. It supports exporting Excellon and Gerber files from Eagle.brd files.
Files Gerber: Gerber is the standard file format used to generate artwork for circuit board imaging.
Files Ivex: Ivex is a viewer that enables previewing production files as interpreted by plotting software. It facilitates exporting Excellon and Gerber files from Ivex.brd files.
Files Protel: Protel is a viewer that previews production files as interpreted by plotting software. It allows exporting Excellon and Gerber files from Protel files.
File Submission: Missing or extra files can delay PCB fabrication. Manufacturers typically request file layers and a drill file. For example, a 4-layer board with silkscreen and soldermask requires 7 layers and a drill file. Missing files or conflicting information in extra files (e.g., readme or old tool files) can cause delays.
Film Artwork: Film artwork is a positive or negative film section containing circuit patterns, nomenclature, or solder masks.
Fine Line Design: Fine line design allows two to three traces between adjacent pins of a Dual In-line Package (DIP).
Fine Pitch: Fine pitch refers to chip packages with lead pitches less than 0.050″, ranging from 0.020″ (0.5 mm) to 0.031″ (0.8 mm).
Finger: A finger is a gold-plated terminal on a card-edge connector, also known as a gold finger.
Finished Copper: Finished copper refers to the combined weight of base and electroplated copper per square foot of material.
First Article: A first article is a sample part or assembly produced to verify that the manufacturer meets all design requirements before full-scale production begins.
Fixture: A fixture is a device that interfaces a PCB with a spring-contact probe test pattern.
Flash: Flash is a small image on film created based on Gerber file commands. The most common size is ¼ inch, though maximum sizes vary by photo plotting shop.
Flat: A flat, or panel, is a standard-sized laminate sheet processed into one or more circuit boards.
Flex Circuit: A flex circuit, or flexible circuit, is a printed circuit made from thin, flexible material.
Flexible Circuitry: Flexible circuitry consists of conductors bonded to a thin, flexible dielectric. Its benefits include circuit simplification, enhanced reliability, reduced size and weight, and a wider operating temperature range.
Flexible Printed Circuit (FPC): FPC, also known as FC, is a type of flex circuit.
Flux: Flux is a material used to remove oxides from surfaces to be joined by welding or soldering, promoting surface fusion.
Flip-Chip: Flip-chip is a mounting technique where a chip (die) is inverted and directly connected to a substrate, bypassing traditional wire bonding. Examples include solder bump and beam lead methods.
Flying Probe: A flying probe is an electrical test machine that uses mechanical arms with probes to touch and locate pads on a board, verifying net continuity and resistance to adjacent nets.
Footprint: A footprint is the space or pattern on a board occupied by a component.
FPC: See Flexible Printed Circuit or flex circuit.
FPPY: FPPY stands for First Pass Panel Yield, representing the number of good panels after defective ones are deducted.
FR-1: FR-1 is a flame-retardant industrial laminate, a lower-grade version of FR-2.
FR-2: FR-2 is a NEMA-grade industrial laminate with a paper substrate and phenolic resin binder. It is cost-effective and suitable for PCBs.
FR-3: FR-3 is similar to FR-2 but uses epoxy resin as a binder.
FR-4: FR-4 is a widely used NEMA-grade flame-retardant laminate with a woven-glass fabric substrate and epoxy resin binder. Its dielectric constant ranges from 4.4 to 5.2 at below-microwave frequencies, decreasing above 1GHz.
FR-6: FR-6 is a cost-effective, flame-retardant laminate with a glass-and-polyester substrate, commonly used in automotive electronics.
Functional Test: Functional testing simulates the operations of an electronic device to confirm its proper functionality.
G
G10: G10 is a laminate, which consists of a woven epoxy-glass cloth infused in epoxy resin under heat and pressure. This laminate finds its use in thin circuits, for example watches. G10 does not have the anti-flammability properties like FR-4.
GC-Prevue: GC-Prevue is a Gerber viewer made by GraphiCode. It is also referred to as a CAM file viewer and printer. It helps store NC drill and Gerber files in a .GWK extension file. This makes GC-Prevue very valuable, when it comes to sharing electronic data. It is a freeware, and anyone can download it. This viewer can be used to import Gerber files in logical sequence, and display them in perfect register. Labels can also be added to the filenames. This helps describe the use and position of Gerber files in the stackup. This process of adding labels is also termed as annotating. After annotating, these files are viewed with the help of GC-Prevue, and the necessary data is saved. The resulting .GWK file is then passed on for further examination. GC-Prevue not only views and prints the files, but also helps measure size of the objects, as well as their relative distance from each other. Unlike other Gerber viewers, GC-Prevue helps set-up and save Gerber data in one single file. Other Gerber viewers require one file to set-up the Gerber files, and then requires an upgrade for saving these files.
Gerber File: Gerber file is named after Gerber Scientific Co., who invented the vector photoplotter. Gerber file is a data file, which is used to control a photoplotter.
GI: GI refers to the woven glass fiber laminate, which is impregnated with polyamide resin.
GIL Grade MC3D: GIL Grade MC3D is a composite laminate, which consists of woven-glass surface sheets on either sides of glass paper core. This laminate has low and stable dissipation and dielectric factor. It shows exceptional electrical properties.
Glass Transition Temperature: Glass transition temperature, is the temperature at which the amorphous polymer changes its form from a brittle and hard condition to a soft, rubbery or viscous one. During this transition of temperature, a number of physical properties, such as brittleness, coefficient of thermal expansion, hardness, and specific heat experience noteworthy changes. This temperature is denoted by Tg.
Glob Top: Glob top is used for protecting the chip and wire bonds on a chip-on-board, and packaged IC. It is a blob made from plastic material, which is non-conductive, and is generally black in color. The material used in the glob top has a low coefficient of thermal expansion, which protects the wire bonds from ripping loose in case of changes in ambient temperatures.
Glue Deposit: This occurs when glue is placed automatically at the center of a component. Glue deposit acts as a bonding agent between the circuit board and the component, thus providing an additional structural integrity.
Gold Finger: Refer to finger.
Gold Plated: It is the process in which a thin layer of gold is deposited on the surface of other metal, such as silver, or copper. This is done by electrochemical plating process.
Golden Board: Golden board is an assembly, or a board, which is free from any defects. It is also referred to as Known Good Board.
Grid: A grid is a network of two sets of parallel lines, which are equidistant. These lines form an orthogonal network. A grid is mainly used to locate points on a Printed Circuit Board (PCB).
Ground: Ground, which is also referred to as earth, is a common reference point for heat sink, shielding, and electric current return.
Ground Plane: Ground plane is a conductor layer that provides a common reference for heat sinking, shielding, as well as electrical circuit returns.
H
Haloing: Haloing refers to a fracturing delimitation that is induced mechanically on or below the surface of base material. Haloing is either shown by a light area around the holes, or other machine areas. It can also be exhibited by both light, as well as machine areas.
Hard Board: A hard board refers to a rigid circuit board.
Hard Copy: Hard copy is the plotted or printed form of a computer data file or an electronic document.
HASL: HASL, which stands for Hot Air Solder Leveling, is a type of finish used on PCBs. In this process, the PCB is inserted into the molten solder bath. This covers all the exposed copper surfaces with solder.
HDI: HDI refers to High Density Interconnect. It is an extremely fine-geometry multi-layer PCB, which is built using conductive microvia connections. Generally, these boards are made by sequential lamination technique. HDI consists of buried and/or blind vias.
Header: The part of a connector assemble, which is mounted on a PCB is termed as a header.
Heavy copper PCB: Heavy copper PCBs are those circuit boards having more than 4 oz of copper.
Hermetic: Hermetic refers to the process of sealing an object airtight.
Hole: In a semiconductor, hole is the term, which is used to define the absence of an electron. Other than the positive charge that it carries, a hole has all the electrical properties as that of an electron.
Hole Breakout: The condition in which a hole is not surrounded by land completely, is termed as hole breakout.
Hole Density: Hole density refers to the number of holes present in a unit area of a PCB.
Hole Pattern: Holes on a printed circuit board are arranged in a pattern with respect to a reference point. This arrangement of holes is referred to as hole pattern.
Hole Void: It is the void present in the metallic deposit of a plated-through hole, which exposes the base material.
HPGL: HPGL stands for Hewlett-Packard Graphics Language. It is a text-based data structure of pen-plot files. These pen-plot files are very essential is driving the Hewlett-Packard pen plotters.
Hybrid: Any circuit, which is made from the combination of discrete component, monolithic IC, thick film, and thin film, is termed as a hybrid circuit.
I
Imaging: When electronic data is transferred to the photo-plotter, it uses a light to transfer negative image circuitry pattern onto the panel. This process is called Imaging.
Immersion Plating: It is a type of surface coating in which a thin metal coating is applied on the surface of another base metal, by partial displacement of the base metal.
Impedance: The resistance offered by an electrical network consisting of inductance reaction, resistance, and capacitance, to the flow of current is referred to as impedance. The impedance of a circuit is measured in Ohms.
Immersion Coating:
- This is an electroless copper coating performed during the through-hole plating.
- The electroless deposition of nickel, tin, or silver and gold to holes and pads for creating a solderable finish. Immersion coating might also be applied on tracks for specific reasons.
Inclusions: The entrapment of foreign particles, metallic or non-metallic, inside any insulating material or conductive layer of a printed circuit board is called as inclusions.
In-Circuit Test: In-circuit test refers to the electrical test performed on individual components in the printed circuit board (PCB) assembly, rather than testing the whole circuit.
Integrated Circuit: Integrated circuit, which is also referred to as an IC, is a miniaturized electronic circuit, which consists of both active, as well as passive components.
Inner Layers: Inner layers refer to the layers of metal foil or laminate that are pressed on the inside of a multilayer circuit board.
Inkjetting: Inkjetting is the process in which well-defined ink dots are dispersed on a printed circuit board. This is done with the help of an equipment, which uses heat for liquefying the solid ink pellet. After the ink has turned into liquid form, it is dropped on the printed surface, with the help of a nozzle. The ink dries quickly.
Insulation Resistance: Insulation resistance refers to the electrical resistance that is offered by an insulating material under specific conditions. This resistance is determined between a pair of grounding devices, contacts, or conductors in different combinations.
Inspection Overlay: Inspection overlay is a negative or positive transparency. It is generally used as an inspection aid, and is made from the production master.
Inspection Guidelines: Inspection guidelines are a set of procedures or rules set by IPC, which is the final American authority on how to design and manufacture PCBs. All circuit boards should meet the IPC Class 2 guidelines.
Internal Power and Ground Layers: Internal power or ground layers refer to the solid copper plains of a multi-layer board, which either carry power or are ground.
Interconnect Stress Test: Interconnect stress test is a system, which is specially designed to measure the ability of the total interconnect to survive both mechanical, as well as thermal strains. This test is carried out from the as manufactured state to that state, in which the product reaches the point of interconnect failure.
Interstitial Via Hole: An interstitial via hole refers to an embedded through-hole, which has a connection of two or more than two layer of conductor in a multilayer printed circuit board.
IPC: IPC is the Institute for Interconnecting and Packaging Electronic Circuits. It is the final American authority, which defines how to design and manufacture printed circuit board.
J
Jump Scoring: Jump scoring in printed circuit boards allows the score line to jump over the panel border, resulting in a stronger assembly panel.
Jumper Wire: A jumper wire refers to an electrical connection, which is formed between two points on a printed circuit board. This connection is formed by a wire after the proposed conductive pattern is created.
K
Kerf: It allows extra space for any hardware to be attached to the board. This happens due to the widening of the rout path on the blueprint.
Keying Slot: Keying slot refers to a slot present in a PCB. This slot is responsible for polarizing the printed circuit board. Thus, it only allows the PCB to be plugged into its mating receptacle. The pins can be properly aligned. This polarization prevents incorrect plugging, which can happen due to reversing or if the pin is plugged in other receptacle.
Known Good Board: The type of circuit board or assembly, which is confirmed to be defect-free. This type of board is also known as golden board.
L
Laminate: Laminate is a basically a composite material, which is formed by attaching and bonding two or more layers of either same or different materials.
Lamination: Lamination is the process of creating a laminate. This process is carried out under heat and pressure condition.
Laminate Thickness: Laminate thickness means the thickness of metal-clad base, which can either be single-sided or double-sided. This thickness is measured before any subsequent processing.
Laminate Void: The cross-sectional area should normally contain epoxy resin. If it is not present in the cross-sectional area, then it is referred to as laminate void.
Laminating Presses: Laminating presses are multilayer equipment used for manufacturing multilayer boards. These equipment apply heat and pressure to laminate and pre-preg to get the desired output.
Leakage Current: Leakage current is caused due to a non-perfect capacitor. Current leaks generally occur when an insulator present between the conductors of a dielectric is not a perfect non-conducting material. This leads to the energy discharge or loss of energy of a capacitor.
Land: Land, which is also referred to as a pad, is the portion on a printed circuit board, with conductive pattern. This portion is specially designated for attaching or mounting electronic components.
Landless Hole: Landless hole, which is also referred to as padless plated hole, is a plated through hole, which does not have land(s).
Laser Photo Plotter: It is a photo plotter equipment, which uses laser. It uses a software to stimulate a vector photo-plotter, and produces a raster image of individual objects in the CAD database. An image is then plotted as a series of lines of dots by the photo-plotter. It has a very fine resolution. A laser photo-plotter is better than a vector plotter in terms of consistent plotting and accuracy.
Lay Up: Lay up is the process of assembling the already treated copper foils and pre-pregs for the purpose of pressing.
Layers: The indication of the different sides of a printed circuit board is given by the layers. On-board text, which consists of part number, company name, and logo is oriented right-reading on the top layer. This helps users determine in no time whether the files have been correctly imported or not. Thus, by taking this simple step, it can save a considerable amount of potential hold up and time-consuming hold notice.
Layer Sequence: As the name suggests, layer sequence is used to determine the sequence in which layers are required to be arranged to get a desired stack-up. It is very much helpful to CAD, and helps determine the type of the layer.
Layer-to-Layer Spacing: In a multilayer printed circuit board, the thickness of a dielectric material between conductive circuitry or adjacent layers is termed as layer-to-layer spacing.
Liquid Resist: The fabrication of circuits makes use of liquid form of photoresist, which is referred to as liquid resist.
Legend: Legend refers to a format of symbols or printed letters on a printed circuit board, for example, logos, part numbers, or product numbers.
LGA: LGA stands for land grid array. It is the surface mount packaging technology, which is used for Integrated Circuits (ICs) that have the pins on socket (if a socket is used) rather than the IC. One can electrically connect the land grid array to a printed circuit board either by soldering to the board directly or by the use of a socket.
Lot: Lot refers to the quantity of several printed circuit boards that have similar or common design.
Lot Code: Lot code is useful for some customers. Therefore, the lot code of a manufacturer is placed on the circuit boards. This helps for the purpose of future tracking. The location, or details such as whether the layer is to be in copper, mask opening, or silkscreen is represented and specified in a drawing.
LPI: LPI refers to the ink, which is used to control deposition. This ink is developed with the help of photographic imaging techniques. LPI is considered to be one of the most precise techniques for applying mask. This technique delivers mask that is thinner compared to that of a dry film solder. Therefore, LPI is mostly a preferred choice for dense surface mount technology. It can be used for applications like spray or curtain coat.
M
Major Defect: A defect that may result in failure of the circuit or significantly reduce its usability is referred to as major defect.
Mask: This is a material applied on the printed circuit board to enable plating, etching or application of the solder.
Master Aperture List: An aperture list that can be used for two or more PCBs is called the master aperture list for that set of PCB.
Measling: A condition found in the base laminate in the form of crosses or white spots. Generally, it is found below the base laminate, and shows the fiber separation in the glass cloth.
Metal Electrical Face (MELF): A surface mounted discrete part, that is cylindrical, or barrel shaped anode. The barrel ends are metal capped. The barrel is laid on its side, the metal pads are laid on landing pads, and the part is soldered. The most common sizes are MLL41 and MLL34, which are MELF versions of DO – 35 and DO – 41 respectively.
Met Lab: Metallurgy laboratory. 1) It refers to processes of inspecting the board quality characteristics through micro sections. 2) The term is used as an alternative to micro sections.
Metal Foil: These are thin rolls or sheets of conductors, which are used to build a printed circuit board. Generally, copper is used as a metal foil.
Micro Ball Grid Array: Also, known as micro BGA. This is a fine pitch ball grid array. Generally, the fine pitch for BGA is less than or equal to 0.5mm. The MGA is very dense, and it is manufactured using controlled-depth laser-drilled blind microvia-in-pad technology.
Micro Circuits: These are very fine lines 2 mil or less, and small micro vias 3 mil or less.
Micro Sectioning: It a process of preparing a specimen for examination under the microscope. A specimen is cut into a cross section, followed by polishing, encapsulation, staining, etching, etc.
Microvia: It is used to connect two adjacent layers that are less than 6 Mil in diameter. Microvia may be formed through plasma etching, laser ablation, or photo processing.
Mil: One thousand of an inch 0.001″ (0.0254mm). This is an abbreviation of milli inch.
Minimum Annular Ring: This is the minimum width of the metal at the narrowest point, between the outer circumference of the land and the circumference of the hole. This measurement is created on the drilled hole on internal layers of the circuit board with multiple layers. Also, it is made on the edge of the plating found on the outer layers of double-sided printed circuit boards, and multilayer circuit boards.
Minimum Electrical Spacing/Minimum Conductor Spacing: It is the minimum distance between conductors that are lying adjacent to each other. This distance helps prevent corona, dielectric breakdown, or both, between the semiconductors of any given altitude and voltage.
Minimum Traces and Spacing: Traces or Tracks are the wires on a printed circuit board. Spaces are the distance between the pads or the distance between the traces, and distance between a trace and a pad. The order form selection is made on the basis of width of the smallest trace (wire, line, and track) or space between pads or traces.
Minimum Conductor Width: It is the smallest width of any conductor including traces on a printed circuit board.
Minor Defect: This defect is not likely to affect the usability of the component or unit for the purpose intended. It may be kind of departure from the established standards with no significant effect on the bearing or the effective operation of the circuit.
Misregistration: A term symbolizing lack of conformity between successively produced patterns or features.
Molded Carrier Ring (MCR): It is a fine-pitch chip package, which is known for protecting and supporting the leads. The leads are left straight; the lead ends are embedded in a plastic strip, which is termed as Molded Carrier Ring. The MCR is cut off before an assembly, and leads are formed. In this way, delicate leads are protected from damage, just before the assembly.
Monolithic Integrated Circuit: The term is abbreviated as MIC. This is a variant of printed circuit board, which is created within a substrate of semiconductor, with one of the circuit elements formed within a substrate. The term is also used for a complete circuit board that is fabricated as an assembly of circuit elements in a small structure. This circuit cannot be divided without destroying its electronic function.
Mounting Hole: A hole used for mechanically supporting a printed circuit board or attaching components to the printed circuit board is termed as mounting hole.
Multilayer Circuit Board: A term for printed circuit board comprising of several layers of insulating materials or conductive patterns that are bonded together in multiple layers.
Multimeter: It is a test instrument that is used to measure current, voltage, and resistance. This instrument is portable in nature.
N
Nail Heading: This is a flared connection of copper formed on an interconnect layer of the multilayered circuit board. Nail heading is brought by poor drilling.
NC Drill: A Numerical Control (NC) drill machine, which is used to drill holes at identified locations on a PCB following an NC drill file.
NC Drill File: This is a text file that guides an NC drill machine to drill holes.
Negative:
- A reverse image copy of a positive checking revision of a PCB. This copy represents planes on the inner layer. A negative image used for an inner-layer will have thermals (segmented donuts) and clearances (solid circles) that make connections. These connections are thermally relieved. Also, there are chances that thermals and clearances may isolate holes from the plane.When the negative image of the current version is superimposed over a positive image copy of an earlier version, all areas will appear solid black. The areas where changes have been made will appear clear.
- It is a PCB image that represents copper as clear areas, and void areas (where material is absent) as black areas. This is typical of solder mask and ground planes.
Net: It is a collection of terminals, which must be electrically connected. The synonym of this term is signal.
Netlist: It is a list of names of parts, or symbols, as well as their connection points that are connected logically in a net of a circuit. The Netlist can be captured from schematic drawing files of electrical CAE application.
Node: A lead or pin to which at least two or more components are connected is referred to as a node. These components are connected using conductors.
Nomenclature: The identification symbols that are applied to the circuit board by inkjetting, screen printing, or laser processes.
Nonfunctional Land: It is the land featuring internal or external layers, which are not connected to the conductive pattern on layer.
Non-plated Through Hole (NPTH): A drill drawing is used to identify NPTH in a PCB design. Most design packages calculate the amount of clearance around a NPTH and plated hole differently. This is because the non-plated holes may end up with less allowance, while passing through power planes and solid copper ground.
Notation: Notation is a PCB diagram that indicates location and orientation of components.
Notch: Also known as a slot, this is seen on the external layers of a circuit board. Generally, notches are seen in mechanical layers that are used for routing.
Number of Holes: As the name suggests, it refers to the total number of holes in a circuit board. There is no limit on the quantity of holes on the circuit board, and it doesn’t influence pricing.
O
One Ounce Foil: It is the weight of 1 square foot of copper foil. (1 Oz= 0.00134 inches, ? Oz = 0.0007 inches, etc.).
Open Circuit: It is an unwanted break in an electric circuit’s continuity that hampers the continuous current flow through the circuit.
OSP: OSP refers to Organic Solder Preservative, and is also known as Organic Surface Protection. It is a lead-free procedure that helps PCB manufacturers meet the requirements of RoHS compliance.
Outer Layer: The top and bottom layer of any circuit board.
Outgassing: Emission or deaeration of gas from a printed circuit board, when it is exposed to vacuum or soldering operation.
Overhang: This is an increase of the conductor width. Overhang is generally brought by plating build-up or undercutting during the etching process.
Oxide: A chemical treatment that is performed to the inner layers of the PCB prior to lamination. This treatment is performed to increase clad copper roughness, and to improve its laminated bond strength.
P
Package:
- A printed circuit board component or a decal.
- A PCB component that contains a chip, and acts to create a convenient mechanism to protect the chip on the shelf, or after attachment to a PCB. With leads soldered to a circuit board, a package may serve as an electrical conduction interface between the board, and the chip.
Pad: The conductive pattern portions on circuit boards that are designated for attaching or mounting components.
Pad Annulus: This refers to the width of the metal ring around a hole in the pad.
Panel: A rectangular sheet of metal-clad material or base material of a particular size, which is used for processing printed circuit boards. Also, a panel for printing one or more test coupons. This is mostly an epoxy-copper laminate known as FR-4. The most common panel size is 12? by 18?, of which 11? by 17? is used for printed circuitry.
Panelize:
- An act of laying one or more identical printed circuits on a panel. All individual printed circuits placed on a panel should maintain a 0.3? margin. However, some board houses permit or create less separation.
- An act of laying multiple printed circuits or modules into a sub-panel, which can be easily assembled as a unit. The modules can be separated post-assembly into separate printed circuits.
Part: It is used in various contexts:
- A component
- A decal in a PWB database or drawing
- A schematic symbol
Part Number: The number or name associated with your circuit board for your convenience.
Pattern: This refers to the configuration of conductors and non-conductive materials on a panel of a circuit board. It is also the circuit configuration on drawing, related tools, and masters.
Pattern Plating: The selective plating performed on conductor pattern.
PCB Array: These are the boards that are supplied in a pallet form. These are sometimes referred to as “stepped out”, “panelized”, “palletized”, “rout and retain”.
PCB Database: It comprises of all essential PCB design data. It is generally stored on a one or more files on a computer.
PCB –Design Software Tools: As the name suggests, these are various software driven tools that enable a PCB designer to conduct a schematic, design a layout, routing, and perform optimizations. There are various PCB design software and tools available for purchase. Here is a very short list of those: ExpressPCB, EAGLE, PROTEL, CADSTAR, ORCAD, CIRCUIT MAKER, P-CAD 2000, PCB ELEGANCE, EDWIN, VISUALPC, BPECS32, AUTOENGINEER, EXPERT PCB, CIRCAD, LAYOUT, CIRCUIT LAYOUT, MCCAD, DREAM CAD, E-CAD, POWERPCB, PCB ASSISTANT, PCB DESIGNER,QCAD, QUICK ROUTE, TARGET 3001, WIN CIRCUIT 98, BOARD EDITOR, PCB, VUTRAX, CIRCUIT CREATOR, PADSPCB, DESIGN WORKS, OSMOND PPC, LAY01, SCORE, GElectronic, PRO-Board, PRO-Net , CSIEDA, VISUALPCB, WINBOARD, ULTIBOARD, EASY PC, RANGER, PROTEUS, EPD -Electronics Packaging Designer , AutoTrax Eda, Sprint Layout, CADINT, KICAD, Merlin PCB Designer, FREE-PCB, TinyCAD, WINQCAD, Pulsonix, DIPTRACE.
PCB Design Service Bureau: A company that offers PCB design service. The word bureau is French term for desk, or office. Also, this service is performed from an office at a desk. Many times, such bureaus are also referred to as PCB design shops.
PCB Prototype: A printed circuit board that is manufactured for testing purposes. In many cases, prototypes are manufactured for a specific application. The prototyping also includes all various aspects of a production. Hence, it helps streamline the product development, and production process, while helping reduce costs.
PCB Fabrication Process: The process of PCB fabrication can be simplified as: Copper laminate>>Drill board > Cu deposition>> Photolithography >> Tin lead plate or finishing >> Etch >>Hot air level >> Solder mask >> E-testing >> Routing/scouring>> Product inspection >> Final cleaning >> Packaging. Most manufacturers follow the same process, but there may be slight variations across various organizations.
PCMICA: This stands for Personal Computer Memory Card International Association
PEC: Printed Electronic Component.
Phenolic PCB: This laminate material is comparatively cheaper than fiber glass material.
Photographic Image: This is an image in an emulsion or in a photo mask that is on the plate or film.
Photo Print: A process of creating a circuit pattern image by hardening a polymeric, photosensitive material. A ray of light is made to pass through photographic film, which helps harden a photosensitive material.
Photo Plotting: In this process, an image is generated by directing a light beam over a light-sensitive material.
Photo-Resist: A material that is sensitive to portions of the spectrum of light. A light sensitive material is applied to the PCB panel under production, and is exposed to develop the pattern from the photoplot. The remaining copper, which remains uncovered by the resist is etched away, and the copper pattern needed for the board remains behind.
Phototool: This is printed by the photo plotter to be used for creating a copper pattern. This is also used for making patterns for silkscreen and soldermask.
Plasma Etching: This process is performed for removal of copper from the PCB panel, whenever special RF materials are used. These RF materials cannot be processed through standard etching procedures.
Plated Hole: This refers to a hole that is drilled on a circuit board, and has completed a plating process. The plated holes conduct electricity, as opposed to non-plated holes. The plated holes are used to connect traces over different layers of a PCB.
Printed Circuit Board: Abbreviated as PCB. Alternatively, known as Printed Wiring Board (PWB). It is a base of insulating material with a pattern of conducting material lying over them. This circuit board starts conducting electricity, when components are soldered to it.
Pre-Peg: Check B-stage.
Probe Test: A metal load with spring loading, which is used for making an electrical contact between test equipment, and the unit under test.
Push-back: A PCB panel whose board units are punched out, and then reset to their original positions through a second operation.
Pulse Plating: This is a method of plating using pulses.
Q
QFP: QFP refers to Quad Flat Pack, which is rectangular, or square in shape. It is a fine-pitch SMT (Surface Mount Technology) package having gull-wing shaped leads on its four sides. Generally, the lead pitch of a QFP is either 0.65 mm or 0.8 mm, in spite of the variations in this theme with small lead pitches. The pitches of these variants are as follows:
- Thin QFP (TQFP): 0.8mm
- Plastic QFP (PQFP): 0.65mm (0.026″)
- Small QFP (SQFP): 0.5mm (0.020″)
These packages can have their lead counts varying from 44 leads to 240 leads, or sometimes even more. Though these are descriptive terms, they do not have any industry-wide standards for sizes. To have a detailed understanding of a particular manufacturer’s part, a printed circuit designer requires a specification sheet of the part. For example, a short description such as PQFP-160, is not sufficient for describing the lead pitch and mechanical size of the part.
Quantity: Quantity is basically used to produce the data in the Price Matrix price table.
Quick Turn: Quick turn refers to fast turnaround provided by a PCB manufacturer. It is defined as fulfilling a request in a less amount of time.
R
Rats Nest: A rats nest or ratsnest is a bunch of straight lines between pins, forming a crisscross pattern on the board. As the name suggests, it forms a confusing mess, which is similar to a rat’s nest. It helps suggest potential paths for routing between a set of connected connectors. Rats nest graphically represents the connectivity of a Printed Circuit Board (PCB) Computer Aided Design (CAD) database.
Readme File: Readme file is a text file, which provides information required for manufacturing an order. It is typically included in a zip file. It is always advisable to include the email addresses and phones numbers of engineers or designers. This helps accelerate the problem solving process at the manufacturing stage.
Reference Designator: A reference designator, which is abbreviated as Ref Des, is the name given to a component. It helps identify the component on a printed circuit board. Reference designator typically starts with a letter, and is followed by a numeric value. It consists of one or two letters, which designate the class of the component. These designators are generally placed close to the respective component. It is made sure that a reference designator does not go under the component. It should be visible, after the component is mounted on the PCB. Most of the times, reference designators appear as yellow or white epoxy ink (also called as silkscreen) on a PCB.
Reference Dimension: These are the dimensions that are only provided for informational purpose. Mostly reference dimensions are provided without tolerances, and are not responsible for governing the manufacturing operations.
Reflow: Reflow is the process in which an electrodeposited tin/lead is melted, and then solidified. The resultant surface has its physical characteristics and appearance similar to that of a hot-dipped one.
Reflow Oven: Reflow oven is a device through which boards are passed. These ovens have solder paste deposits.
Reflow Soldering: Reflow soldering is the process in which two coated metal layers are melted, joined, and solidified by applying heat to pre-deposited solder paste and the surface.
Registration: Registration is a standard term, which is used to ensure whether the plotted circuit board is following the design, as well as layout position of components.
Residue: Residue is an unwanted substance that remains on a substrate, even after the completion of a process step.
Resin Smear: Refer to epoxy smear.
Resin-Starved Area: Resin-starved area refers to a localized area on a PCB, which lacks a sufficient amount of resin. This area is mostly identified by exposed fibers, dry spots, low gloss, etc.
Resist: During the manufacturing or testing process, some areas of a pattern might get affected by the action of solder, plating, or etchant. To protect these areas from getting affected, a coating material, which is referred to as a resist, is used.
Resistivity: Resistivity refers to the capability or property of a material to resist the flow of electrical current through it.
Reverse Image: Reverse image is the resist pattern that is present on a printed circuit board, which allows the exposure of conductive areas. This helps in plating.
Revision: Revision refers to updating the data, when the same drawing has an updated version.When the data is updated, it avoids any possible confusion at the time of manufacturing a board to required specifications. Revision number should be always included along with the drawing.
Rework: Rework, which is also termed as reprocessing, is the process of making articles adhere to the specifications.
RF: RF is the short-form used for Radio Frequency.
RF and Wireless Design: Radio frequency or wireless design refers to the circuit design operating in a range of electromagnetic frequencies, which is above the radio range, and below visible light. This operating range varies between 30 KHz and 300 GHz, and all the broadcast transmissions taking place between AM radio and satellites fall into this range.
Rigid-Flex: Rigid-flex is the construction of a built-in connection on multi-layer flex circuits. Rigid-flex PCBs are a combination of rigid and flexible board technology in an application.
Rise Time: After the change has started, a certain amount of time is required for an output voltage of a digital circuit to go from a low voltage level (0) to a high voltage level (1). The technology used in a circuit determines the rise time. The rise time of gallium arsenide components is approximately 100 picoseconds, which is almost 30 to 50 times faster than some CMOS components.
Robber: Robber refers to an exposed area, which is joined to a rack that is used in the electroplating process. A robber is mainly used to get more uniform current density on the parts that are plated.
RoHS: RoHS stands for Restriction of Hazardous Substances. It is a directive laid down in different parts of the world, which puts a restriction on the use of hazardous substances in electronic and electrical equipment.
RoHS Compliant PCB: The circuit boards that adhere to the RoHS directives are referred to as RoHS compliant PCBs.
Route or Track: Route, which is also sometimes referred to as a track, is wiring or a layout of electrical connections on a PCB.
Router: Router is a machine, which is used to cut the unwanted portions of a board to get it into a desired shape and size.
S
Saturation:
- Saturation is the state of a transistor at which increase in the base current has no effect on, or does not increase the collector current any further.
- The operating condition of a circuit, where any change or increase in the input signal has no effect on the output is termed as saturation.
- Saturation is the operating condition or state reached, when a transistor is driven hard enough to make it biased in the forward direction. When a transistor under the saturation condition is used in a switching application, the charge stored in the base region stops the transistor from turning off quickly.
- It is the condition or state at which, for a given applied voltage, a semiconductor device conducts most heavily. Saturation, in most of the devices also refers to the state at which the normal amplification mechanisms become inoperative or “swamped”.
Schematic: Schematic or a schematic diagram is a representation of the elements of a system, with the help of graphic symbols, functions, and electrical connections of a particular circuit arrangement.
Scoring: Scoring refers to a technique in which grooves are made on the opposite sides of a panel. These grooves are machined to a depth that allows separation of each individual board from the panel one the component assembly is done.
Screen: A screen refers to a cloth material, which is coated with a design that decides the location and flow of coatings forced through its openings. The cloth material is either polyester or stainless steel, which makes it suitable for circuit boards.
Screen Printing: Screen printing is a process in which an image is transferred to a surface. This is done by forcing proper media through a stencil screen with the help of a squeegee.
Selective Plate: Selective plate is a process of plating a specific area on a PCB with a different metal. The process of creating a selective plate consists of imaging, exposing, and plating the selected area.
Shadowing: Shadowing is the condition reached during etchback. In this condition, the dielectric material, which is in contact with the foil is not removed completely, though satisfactory etchback is achieved elsewhere.
Short: Short is also referred to as a short circuit. It is an abnormal connection in which the resistance between the two points of a circuit is extremely low. This results in an excess current between these two points, which is capable of damaging the circuit. This abnormal connection can occur in a printed wiring CAD database, when conductors from different nets come closer than the minimum space, which is allowed. This minimum space is decided by the design rules that are being used.
Short Run: Short run in manufacturing of PCBs refers to the requirement in which only one to tens of printed circuit board panels are required to fulfill the order instead of hundreds of them. The short run can be determined on the basis of the size of printed circuit board to be made, and the size of manufacturing facility.
Silkscreen: Silkscreen, which is also sometimes referred to as silkscreen legend, can be defined in two ways as follows:
- Silkscreen is generally used on the component side. It is basically used to identify manufacturer marks, company logos, test points, warning symbols, components, and the part number of PCB and PCBA. It gets its name from the method or type of printing i.e. screen printing. The silkscreen layer is just ink, which is non-conductive. This layer is placed on the traces of a PCB, without any interference.
- Silkscreen is a Gerber file, which helps control the photo plotting of this legend.
Signal Layer: The layers where the conductive traces can be laid out, are referred to as signal layers.
Single-Sided Board: Single-sided boards are circuit boards, which have conductors only on one side. These circuit boards do not have plated-through holes.
Single Track: Single track refers to a PCB design, which has only one route between adjacent DIP pins.
Size X & Y: The dimensions of a printed circuit board are in inches or metric. Maximum X & Y configuration is 108″. This means that if the width (X) of a PCB is 14″, then it can have a maximum length (Y) of 7.71″.
Skip Plate: Skip plate is the area in plating, where metal is not present.
SMOBC: SMOBC stands for Solder Mask Over Bare Copper. It is a method, which is used to fabricate a printed circuit board. SMOBC results in final metallization being copper with no protective metal beneath. In this process, the non-coated areas, are coated using solder resist. Also, the component terminal areas are exposed in this process. This helps eliminate the tin lead that is present under the mask.
SMD: SMD stands for Surface Mount Device. An electronic device, which is made using the Surface Mount Technology (SMT), is termed as SMD.
SMT: Surface Mount Technology (SMT) is a method used for making electronic circuits. In this method, the components are directly mounted on Printed Circuit boards (PCBs). This method is also sometimes referred to as surface mount. In this technology, the components are soldered on the board without making use of holes. This technology is mainly used for creating printed wiring. The result of this technology is higher component density. Besides this, SMT allows smaller printed wiring boards.
Small Outline Integrated Circuit (SOIC): SOIC is a type of surface mounted integrated circuit, which has its pin-out layout similar to that of DIP (Dual-Inline-Package) circuits.
Silicon Wafer: Silicon wafer is a thin disk of silicon consisting of a set of integrated circuits before they are being cut free and packaged. The wafer resembles a music CD, and diffracts the reflected light into rainbow patterns. On observing closely, individual ICs can be seen, which form a uniform patchwork. These ICs are generally square- or rectangular-shaped.
Soft Copy: Soft copy is an electronic form of a document. It can either be stored on a storage media, or can be a data file that is saved in computer memory.
Solder: Solder is an alloy, which is melted to seal or join metals having high melting points. Solder itself as a low melting point.
Solder Balls: Solder balls, which are also referred to as solder bumps are round balls that are bonded to the contact area of a transistor. These balls or bumps are used for connecting conductors with the help of face-down bonding techniques.
Solder Bridging: Solder bridge is an unwanted connection of two conductors. This occurs when a solder blob of solder connects the conductors, and forms a conductive path.
Solder Bumps: Solder bumps refer to round-shaped solder balls that are bonded to component pads. These are mainly used in face-down bonding method.
Solder Coat: Solder coat refers to a layer of solder directly applied to a conductive pattern from a molten solder bath.
Solder Leveling: Solder leveling is a process of removing extra and unwanted solder from holes and lands of a circuit board. This is done by exposing the board to hot air or hot oil.
Solderability Testing: It is the testing method, which determines the ability of a metal to be wetted by solder.
Solder Mask: It is a technique in which everything present on a circuit board is plastic coated except for fiducial marks, the contacts to be soldered, and the gold-platted terminals of any card-edge connectors.
Solder Mask Color: Solder mask can be of different colors, which include blue, red, white, etc.
Solder Paste: It is a paste, which is applied on a PCB or its panel. Solder paste provides a stable placement and soldering of surface mount components.
Solder Paste Stencils: Solder paste stencils are mainly used to make sure that only the right amount of solder paste is applied. This helps realize the finest electrical connections.
Solder Plate: It is a tin/lead alloy, which is plate in a pattern that defines finished features or circuits.
Solder Resists: Solder resists are coatings, which are used to insulate those portions of a circuit patterns that do not require solder.
Solder Wick: Solder wick is a band, which is typically used to remove molten solder from a solder joint or just desoldering. It can also be used to removing the molten solder from solder bridge.
Space Transformer (ST): A space transformer is one of the major components of high-density probe cards, which provides high routing density, pitch reduction, and localized mid-frequency decoupling.
SPC: SPC refers to Statistical Process Control. It is a process of data collection, which monitors the stability and functions of a circuit.
Sputtering: Sputtering is a deposition process, in which a surface (generally referred to as a target) is immersed in an inert gas plasma. Ionized molecules are then bombarded on this target to release surface atoms. Sputtering is based on the target material’s disintegration by ion bombardment.
Squeegee: Squeegee is a tool used to force the ink or resist through the mesh. It is mainly used in silk screening.
SQFP: SQFP, which stands for Shrink Quad Flat Package or Small Quad Flat Package is one of the variants of a QFP. See QFP.
Stacked Vias: As the name suggests, stacked vias are micro vias in High-Density Interconnect (HDI) PCB. These vias are stacked upon each other
Starvation Resin: As the name implies, starvation resin is the deficiency of resin in base material. This deficiency occurs after lamination, as a result of dry spots, low gloss, or weave texture.
Step–and–Repeat: Step-and-repeat is a process of exposing a single image successively for producing a multiple-image production master. This process is used in CNC programs.
Streamlined PCB Design: Streamlined PCB design, which is also referred to as streamlined design or SLPD, is basically a set of policies that help guide the designing of PCBs. The main purpose of deriving these policies is to simplify PCB design and eliminate errors systematically.
Strip: It is the process of removing plated metal or developed photo resist.
Stuff: Stuff refers to the process of attaching and soldering different components to a printed wiring board.
Sub-Panel: Sub-panel is a group of printed circuits, which are also referred to as modules that are arrayed in a panel. A sub-panel is handled by both the assembly house, as well as the board house as if it were a single printed wiring board. Typically, a sub-panel is prepared at the board house. Most of the material separating individual modules are routed, and thus leaving small tabs. These tabs are strong enough to allow the assembly of a sub-panel as a unit. On the other hand, these tabs are also weak enough to enable easy final separation of assembled modules.
Substrate: A substrate is either an active material, which is monolithic compatible, or a passive material, which is thin film and hybrid. It is used as a supporting material for attaching parts of an integrated circuit.
Subtractive Process: Subtractive process is exactly opposite to the additive process. A subtractive process is a process in manufacturing of a printed circuit, wherein an already existing metallic coating is subtracted for building a product.
Surface Finish: Surface finish refers to the type of finish that is required by a customer for a printed circuit board. Regular boards can have surface finishes, such as gold plating, immersion silver, OSP (Organic Solderability Preservative), immersion gold, and HASL (Hot Air Solder Leveling).
Surface ft.: Surface feet refers to the total surface area of a given work piece in feet.
Surface Mount Pitch: The pitch of the surface mount refers to the dimensions from the center to the center of surface mount pads. These dimensions are measured in inches. There are three pitch values as follows:
- Standard pitch: >0.025″
- Fine pitch: 0.011″-0.025″
- Ultra-fine pitch: <0.011″
As the pitch of a board gets fine, the costs of test fixture and processing increase.
Symbol: A symbol is a simplified design, which is used to represent certain part in a schematic circuit diagram.
T
TAB: TAB stands for Tape Automated Bonding. It is a process in which bare Integrated Circuits (ICs) are placed on PCBs by attaching them to fine conductors in a polyimide or polyamide film.
Tab Plate: Tab plate refers to selective plating on edge connectors, typically nickel/gold.
Tab Routing (with & without perforation holes): Tab routing is one of the most widely used approach for PCB panelizing, which is done with or without perforation holes. Non-rectangular boards can be produced with the help of tab routing. It is the optimal way of setting up parts that are relative to the tooling process.
Temperature Coefficient (TC): When temperature changes, electrical parameters, such as capacitance or resistance undergo change. The ratio of the quantity change of these parameters is termed as temperature coefficient (TC). It is expressed in ppm/°C or %/°C.
T/d: The temperature at which a circuit loses 5% of its volume because of outgassing, is termed as temperature of destruction.
Tented Via: It refers to a via having a dry film solder mask, which covers both the plated-thru holes, as well as the pads, is termed as tented via. This helps insulate via from foreign objects, which in turn protects it from accidental shocks.
Tenting: Tenting refers to covering holes of a printed circuit board, along with the surrounding conductive pattern with the help of dry film resist.
Terminal: A terminal is a point of connection, where two or more conductors in a circuit are connected. Generally, one among the two conductors is lead of a component or an electrical contact.
Terminal Block: Terminal block is a type of header. Wires are directly attached to this header without using a connector plug. Terminal blocks have holes through which each wire is inserted and anchored with the help of a screw.
Testing: Testing refers to a method, which makes sure whether assemblies, sub-assemblies, and/or a finished product adhere to a set of parameters and functional specifications. There are different types of testing, such as environmental, reliability, in-circuit, and functional testing.
Test Board: As the name suggests, a test board is a printed board used to determine the acceptability of a group of boards that are or will be produced by the similar fabrication process.
Test Coupon: A test coupon refers to a PCB, which is used to ensure the good quality of a Printed Wiring Board (PWB). These coupons are fabricated on the same panel as that of PWBs. Generally, these coupons are fabricated at the edges.
Test Fixture: Test fixture refers to the device that acts as an interface between the unit under test and the test equipment.
Test Point: As the name implies, test point is a point in a circuit at which different functional parameters are tested.
TG: TG stands for the glass transition temperature. It is the point at which the resin contained in the solid base laminate starts exhibiting soft, plastic-like symptoms. This phenomenon occurs at rising temperatures, and is expressed in degrees Celsius (°C).
Thermal Pad: A thermal pad is a special type of pad, which allows easy conduction of heat towards the heat sink. Typically, a thermal pad is made from paraffin, and helps conduct the heat away from electronic components, thus preventing any damage.
Thief: Thief is a common term used for cathode, which is placed on a board. Thief regulates the current density, which goes through the circuit.
Thin Core: Thin core is basically a thin laminate, which has its thickness less than 0.005 inches.
Thin Film: Thin film refers to film of insulating or conductive material, which is deposited by evaporation or sputtering, which may be made in a pattern. It can either be used to form an insulation layer between successive layers of components, or to form electronic components and conductors on a substrate.
Through-Hole: Through-hole, which is also spelled as thru-hole, is a mounting technique. In this technique, pins are designed to be inserted into holes. These pins are then soldered to pads on a printed circuit board.
Tooling: Tooling is defined as processes and/or costs involved in setting up to manufacture a printed circuit boards’ run for the first time.
Tooling Holes: Tooling holes refer to the holes that are drilled in a printed circuit board, which is used for manufacturing hold-down.
Top side: Top side is that side of a PCB, where components are mounted.
TQFP: TQFP stands for Thin Quad Flat Pack. It is similar to a QFP, excluding low-profile, that is, thinner.
Trace: The segment of a route is termed as trace.
Trace width Calculator: Trace width calculator is a JavaScript web calculator, which is used to determine the trace width of PCB connectors for a given circuit. It is done with the help of the formulas from IPC-2221 (formerly IPC-D-275).
Track: Please see the definition for Trace.
Traveler: A traveler is a formula for manufacturing a circuit board. A traveler identifies each order, and travels from start to finish with each order. Instructions for each step in a process are given by a traveler. Information regarding the history and traceability is also provided by the traveler.
Trillium: The name of a company, which makes ATE and DUT systems.
TTL: TTL stands for Transistor-Transistor Logic. It is the most largely used semiconductor logic, which is also referred to as multiple-emitter transistor logic. The basic logic element of this logic is multiple-emitter transistor. This logic has medium power dissipation and high speed.
Turnkey: Turnkey refers to a type of outsourcing method. This method turns over to the subcontractor for all aspects of manufacturing, which include testing, material acquisition, and assembly. The opposite of turnkey method is consignment, in which all the required materials are provided by the outsourcing company, while the assembly equipment and labor is provided by the subcontractor.
Twist: Twist refers to a defect in the lamination process. This defect causes twisted or uneven arc on the plane printed circuit board.
Two-Sided Board: A two-sided board is the same as double-sided board. Please see the definition for double-sided board.
U
UL: UL is the short form for Underwriter’s Laboratories, Inc. The corporation works for establishing safety standards on different components and equipment. It is supported by some underwriters, and provides inspection, testing, validation, certification, auditing, and advising related to safety.
Unclad: Unclad is a cured epoxy glass, which does not have any copper layer or layers.
Underwriters Symbol: The underwriter’s symbol is basically a logo or symbol, which indicates that a product has been recognized by the Underwriters Laboratory (UL).
Unsaturated Logic: Unsaturated logic is the condition in which transistors operate outside their saturation region. This helps make switching faster. Emitter-coupled logic is one such example of an unsaturated logic.
Unstuffed: Unstuffed is a slang term used in PCB manufacturing, which is not much populated.
US-ASCII: US-ASCII is the 7-bit version of the American Standard Code for Information Interchange (ASCII). It uses character codes 0-127. This version is the basis for the 8-bit versions, such as MacASCII, Latin-1, as well as larger coded character set like Unicode.
UV Cure/UV Curing: UV curing is the process of exposing a material to ultra violet light for the purpose of cross inking, or polymerizing and hardening it.
V
Valuable Final Artwork: Valuable Final Artwork is a term referred in context of “Streamlined PCB design”. The artwork is perfectly suited for activities like numeric control tooling for printed circuit manufacture and photo imaging in the circuit boards. These boards are thoroughly checked for errors and flaws before being dispatched for manufacture. It can be exchanged with any customer for money or any other support, hence it is termed as Valuable.
Vapor Phase: It is a process, where a vaporized solvent is used for heating the solder. The solder is generally heated beyond its melting point to create a durable component-to-board solder joint.
VCC/Vin: The input voltage coming from any external source. The input voltage may come from wall transformers, mains, power outlets, dedicated power supplies, batteries, and solar panels. VCC is related to GND.
VDD or Vdd or vdd: A term used for voltage drain. VDD usually implies a positive voltage.
VEE or Vee or vee: It is also known as Emitter supply of the VEE is usually -5V for ECL circuits. The VEE is associated with the collector and emitter sides of any bipolar transistor like NPN.
Vector Photoplotter: Also known as Gerber photoplotter, this equipment plots a CAD database on a film in a darkroom by drawing a line through a lamp light that is shined through a ring aperture (more precisely an annual ring aperture). The apertures are pieces of thin plastic that are trapezoidal shaped, but featuring a thin transparent portion that controls the shape and size of the light pattern. These apertures are mounted on an aperture wheel. At a time, an aperture wheel can hold 24 apertures. Gerber photoplotters are ideal for printed circuit board artwork creation. Today, large sized vector photoplotters are used for producing large photoplots.
Via or VIA: VIA, also known as vertical interconnect access, are the plated-through holes in the printed circuit boards. These holes are used to make electrical connections between different layers on any printed circuit board.
Via Filling: A process of filling vias to close them. Generally, non-conductive paste is used for the purpose. Via filling is performed on PCBs where large amount of drills are made by vacuum lifter during the fixation. Also, this process helps prevent the runoff of solder. Via filling is basically used on inner layers, where buried vias are found.
VLSI: VLSI stands for Very Large Scale Integration. It is the process of creating integrated circuits where thousands of transistors are combined to form a single chip. It is the successor to large-scale integration (LSI), medium-scale integration (MSI) and small-scale integration (SSI) technologies.
Void: These are the empty spaces on the circuit board, where there are no electronic components or substances present.
VQFP: VQFP stands for Very Thin Quad Flat Pack.
VQTFP: Very Thin Quad Flat Package.
vss or VSS or Vss: It stands for Collector supply voltage. VSS usually implies negative voltage and it is equivalent to GND (ground).
V-Scoring: The edges of the circuit board is “scored” in order to break it apart after the assembly. V-scoring allows the creation of two beveled scoring lines along the perimeter of the board. This allows easy breaking of board afterwards. This method is well-suited for medium to large volume production of panels that require straight cutting. V-scoring requires no space between the units.
W
Warping: This refers to the finished board warp and a twist. All printed circuit boards have warps due to manufacturing. The warp ratio increases, if materials used contain a high level of moisture. Hence, mentioning warping tolerance is very important.
Wave-soldering: A soldering process which involves soldering, pre-heating, and cleaning.
Weave Exposure: This is a surface condition, where unbroken fibers of a woven glass cloth are not completely covered by a resin. Weave exposure is used in reference to a base material.
Weave Texture: A surface condition in which a weave pattern of a glass cloth becomes clearly visible. However, unbroken fibers of the woven cloth are covered with resin.
Wedge Voids: These are basically layer separation defects in a drilled hole. Wedge voids are also sites that retain chemicals.
Wet Solder Mask: A wet epoxy ink is applied on copper traces of a circuit board through a silk screen. A wet solder mask generally has a resolution of a single track design. This means it is not suited for fine-line designs.
WEEE Directive: WEEE Directive is the EU directive 2002/96/EC, which aims to curb increasing amount of electronic waste. WEEE is an abbreviation of Waste of Electrical and Electronic Equipment.
Whisker: A needle-shaped and slender metallic growth on a circuit board.
Wicking: In this process, copper salts are migrated into the glass fibers of an insulating material of a plated hole
WIP: WIP stands for Work in Progress. It is generally used as folder name’s extension or directory where data is stored temporarily denoting the current work in progress.
Wire: Wire is a strand of metallic conductor in the form of a thin flexible thread or rod. When referring to a printed circuit board, a wire can be a route or track.
Wire Bonding: A method of attaching a very fine wire to semiconductor components, to interconnect them. These wires are made from aluminum, which contains 1% silicon. The wires measure 1-2 mm in diameter.
Wire Bondable Gold: This is a soft gold. This coating is softer than most other gold finishes, which means it can be bonded easily for stronger connections. The finish comprises 99% pure gold (24 carat) with typical thickness ranging from 30-50 micro inches of gold.
X
X: X axis refers to the principal horizontal or left-to-right direction axis in a two-dimensional system of co-ordinates.
X-Ray: During the PCB manufacturing, X-ray is used for analyzing BGA components, as well as multilayer circuit boards.
X-Outs: This term is used when an array of PCBs found on a single board fails final inspection or electrical test. The PCBs are “X’ed” out using a marker to indicate that they should not be used. Many times, customers specify percentage of X-outs allowed in an array, whereas others may not tolerate X-outs in an array. This point should be specified while quoting the PCBs because additional costs may be incurred.
Y
Y Axis: Y axis refers to any principal vertical or bottom-to-top direction axis in a two-dimensional system of co-ordinates.
Young’s Modulus: This is amount of force applied by an object, when it expands or contracts as a result of change in temperature.
Yield: In PCB manufacturing, the yield rate refers to the usable PCBs from a production panel.
Z
Z Axis: It refers to an axis, which lies perpendicular to the plane formed by X and Y reference. Z axis usually represents the board’s thickness.
Zero Defects Sampling: A statistical sampling method, where a given sample is inspected for defects. If any defects are found, the entire sample is rejected. It is a statistics based attribute sampling plan (C = O).
Zero Width: This is an outline shape with “O” thickness line width. The most common example is using a polygon to draw shapes or copper fill to define the drawing limit of an entity.