Tools & Tips

In order to get an insight into the fabrication process, it is first needed to understand the PCB Manufacturing Tools and Tips. Following are the enlisted details of PCB tools that are optimum for particular type of assembly process and the required PCB Tips to understand the quality testing procedures.

Printed Circuit Manufacturing Glossary


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Active Components : Semiconductor devices, such as transistors and diodes, that can change its basic characteristics in an powered electrical circuit, such as amplifiers and rectifiers.

Analog Circuit : an electrical circuit that provides a continuous quantitative output as a response from its input.

Annular Ring : That portion of conductive material completely surrounding a hole.

AOI (Automated Optical Inspection) : Automatic laser/video inspection of traces and pads on the surface of inner-layer cores or outer-layer panels. The machine uses cam data to verify copper feature positioning, size and shape. Instrumental in locating “open” traces, missing features or “shorts”.

AQL (Acceptance Quality Level) : The maximum number of defectives likely to exist within a population (lot) that can be considered to be contractually tolerable; normally associated with statistically derived sampling plans.

Array : A group of elements or circuits arranged in rows and columns on a base material.

Artwork : Printed circuit design.

Aspect Ratio : The ratio of the board thickness to the smallest-hole diameter of the Printed Circuit Board.

Assembly File : A drawing describing the locations of components on a PCB.

Automated Test Equipment (ATE) : equipment that automatically tests and analyzes functional parameters to evaluate performance of the tested electronic devices.

Ball Grid Array (BGA) : A SMD package in which solder ball interconnects cover the bottom surface of the package.

Bare Board : An unpopulated PCB.

Base Copper Weight : see Copper Foil

Base Material : The insulating material used to form the conductive pattern. It may be rigid or flexible or both. It may be a dielectric or insulated metal sheet.

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

BBT : Bare Board Test.

Bill of materials (BOM) : A comprehensive listing of all subassemblies, components, and raw materials that go into a parent assembly, showing the quantity of each required to make the assembly.

Board Thickness : The overall thickness of the base material and all conductive material deposited thereon.

Built-In Self Test : An electrical testing method that allows the tested devices to test itself with specific added-on hardware.

CAD : Computer Aided Design.

CAM : Computer Aided Manufacturing.

CAM Files : The files used for manufacturing PCB including Gerber file, NC Drill file and Assembly Drawings.

Card : Another name for a Printed Circuit Board.

Catalyst : A chemical that is used to initiate the reaction or increase the speed of the reaction between a resin and a curing agent.

Center to Center Spacing : The nominal distance between the centers of adjacent features on any single layer of a Printed Board, e.g.; gold fingers and surface mounts.

Ceramic Ball Grid Array (CBGA) : A ball grid array package with a ceramic substrate.

Chip-on-Board (COB) : A configuration in which a chip is directly attached to a Printed Circuit Board or substrate by solder or conductive adhesives.

Chip : The individual circuit or component of a silicon wafer, the leadless form of an electronic component.

Component : Any of the basic parts used in building electronic equipment, such as a resister, capacitor, DIp or connector, etc.

Component Hole : A hole that is used for the attachment and/or electrical connection of component terminations, including pins and wires, to a printed board.

Component Side : The Side of a PCB on which most of components are mounted.

Curing : The irreversible process of polymerizing a thermosetting epoxy in a temperature-time profile.

Curing Time : The time needed to complete curing of an epoxy at a certain temperature.

Delamination : A separation between plies within a base material, between a base material and a conductive foil, or any other planner separation with a printed board.

Design Rule Checking : The use of a computer-aided program to perform continuity verification of all conductors routing in accordance with appropriate design rules.

Desmear : The removal of friction-melted resin and drilling debris from a hole wall.

Dewetting : A condition that results when molten solder has coated a surface and then receded. It leaves irregularly shaped mounds separated by areas of thin solder. The base material is not exposed.

Die : Integrated circuit chip as diced or cut from a finished wafer.

Die Bonder : The placement machine bonding IC chips onto achip-on-board substrate.

Die Bonding : The attachment of an IC chip to a substrate.

Dielectric : An insulating medium between conductors.

DIP : Dual in-line package with two rows of leads from the base in standard spacing between the leads and row. DIP is a through-hole mounting package.

Double-Sided Assembly : PCB assembly with components on both sides of the substrate.

Dry - Film Resists : Coated photosensitive film on the copper foil of PCB using photographic methods. They are resistant to electroplating and etching processes in the manufacturing process of PCB.

Edge Connector : A connector on the circuit-board edge in the form of gold plated pads or lines of coated holes used to connect other circuit board or electronic device.

Edge Clearance : The smallest distance from any conductors or components to the edge of the PCB.

Electrod Eposition : The deposition of a conductive material from a plating solution by the application of electrical current.

Electroless Deposition : The chemical coating of a conductive material onto a base material surface by reduction of metal ions in a chemical solution without using electrodes compared to electroplating.

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

Etchback : The controlled removal by a chemical process, to a specific depth, of nonmetallic materials from the sidewalls of holes in order to remove resin smear and to expose additional internal conductor surfaces.

Etching : The chemical, or chemical and electrolytic, removal of unwanted portions of conductive or resistive material.

ESR : Electro-statically applied Solder Resist.

Fine pitch : Fine pitch is more commonly referred to surface-mount components with a lead pitch of 25 mils or less.

Finger : A gold-plated terminal of a card-edge connector. Also see Gold Finger.

Flux : The material used to remove oxides from metal surfaces and enable wetting of the metal with solder.

FR4 : Flame Retardant laminate made from woven glass fiber material impregnated with epoxy resin.

Functional Test : The electrical testing of an assembled electronic device with simulated function generated by the test hardware and software.

Gerber File : Data file used to control a photo plotter.

Ground Plane : A conductive plane as a common ground reference in a multilayer PCB for current returns of the circuit elements and shielding.

GI : The woven glass fiber laminate impregnated with polyimide resin.

Gold Finger : The gold-plated terminal of a card-edge connector. Also see Finger.

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

HDI (High Density Interconnect) : Ultra fine-geometry multi-layer PCB constructed with conductive microvia connections. These boards also usually include buried and/or blind vias and are made by sequential lamination.

Hole Breakout : A condition in which a hole is not completely surrounded by the land.

Hole Density : The number of holes per unit area on a PCB.

Immersion plating : The chemical deposition of a thin metallic coating over certain basis metals that is achieved by a partial displacement of the basis metal.

Impedance : The resistance to the flow of current, represented by an electrical network of combined resistance, capacitance and inductance reaction, in a conductor as seen by an AC source of varying time voltage. The unit of measure is ohms.

Inclusions : Foreign particles, metallic or nonmetallic, that may be entrapped in an insulating material, conductive layer, plating, base material, or solder connection.

Inkjetting : The dispersal of well-defined ink "dots" onto a PCB. Inkjet equipment uses heat to liquefy a solid ink pellet and change the ink into a liquid, which is then dropped via a nozzle onto the printed surface, where it quickly dries.

Interstitial Via Hole : An embedded through-hole with connection of two or more conductor layers in a multilayer PCB

IpC (The Institute for Interconnecting and packaging Electronic Circuits) : - The final American authority on how to design and manufacture printed wiring.

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

Laminate : A product made by bonding together two or more layers of materials.

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

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

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

Laser Photo-Plotter : A plotter that uses a laser, which simulates a vector photo-plotter by using software to create a raster image of the individual objects in a CAD database, then plots the image as a series of lines of dots at a very fine resolution. A laser photo-plotter is capable of more accurate and consistent plots than a vector plotter.

Lead : A terminal on a component.

Legend : A format of lettering or symbols on the Printed Circuit Board: e.g. part number, serial number, component locations, and patterns.

LPI (Liquid Photo-Imageable Solder Mask) : - An ink that is developed off using photographic imaging techniques to control deposition. It is the most accurate method of mask application and results in a thinner mask than dry film solder mask. It is often preferred for dense SMT. Application can be spray, curtain coat or squeegee.

Mil : One thousandth of an inch.

Mounting Hole : A hole that is used for the mechanical support of a printed board or for the mechanical attachment of components to a printed board.

Minimum Conductor Width : The smallest width of any conductors, such as traces, on a PCB.

Minimum Conductor Space : The smallest distance between any two adjacent conductors, such as traces, in a PCB.

Multilayer PCB : Circuit boards consisting three or more layers of printed circuits separated by laminate layers and bonded together with internal and external interconnections.

NC Drill : Numeric Control drill machine used to drill holes at exact locations of a PCB specified in NC Drill File.

Netlist : List of parts and their connection points which are connected in each net of a circuit.

Node : A pin or lead to which at least two components are connected through conductors.

NPTH : Non-plated trough-hole.

Open : Open circuit. An unwanted break in the continuity of an electrical circuit which prevents current from flowing.

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

Pad : The portion of a conductive pattern for connection and attachment of electronic components on the PCB. Also called Land.

PCB : Printed Circuit Board. Also called Printed Wiring Board (PWB)

Panel : Material (most commonly an epoxy- copper laminate know as FR-4) sized for fabrication of Printed Circuit Boards. The standard size at PCB Assembly is 18” x 24”.

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

Pattern Plating : The selective plating of a conductive pattern.

Photo Resist : A material that is sensitive to portions of the light spectrum and that, when properly exposed can mask portions of a base metal with a high degree of integrity.

Plating : The chemical or electrochemical deposited metal on a surface.

Plated-Through Hole : A hole in a PWB with metal plating added after it is drilled. Its purpose is to serve either as a contact point for a through-hole component or as a via.

Positive : A developed image of photo-plotted file, where the areas selectively exposed by the photo plotter appear black and unexposed areas are clear. For outer-layers, color will indicate copper. Positive inner-layers will have clear areas to indicate copper.

Prepreg : A sheet of material that has been impregnated with a resin cured to an intermediate stage. I.e. B-stage resin.

Printed Circuit Board : A flat plate or base of insulating material containing a pattern of conducting material. It becomes an electrical circuit when components are attached and soldered to it. The conducting material is commonly copper which has been coated with solder or plated with tin-lead alloy. The usual insulating material is epoxy laminate but there are many other kinds of materials used in more exotic technologies. Single sided boards have all conductors on one side of the board. With two-sided boards, the conductors, or copper traces, can travel from one side of the board to the other through plated-thru holes called vias, or feed through. In multilayer boards, the vias can connect to internal layers as well as either side.

Reflow Soldering : Melting, joining and solidification of two coated metal layers by application of heat to the surface and pre-deposited solder paste.

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

Route (or Track) : A layout or wiring of an electrical connection.

Schematic : A diagram which shows, by means of graphic symbols, the electrical connections and functions of a specific circuit arrangement.

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

SMOBC : Solder mask over bare copper.

SMD : Surface Mount Device.

SMT : Surface Mount Technology.

Solder Bridging : Solder connecting, in most cases, misconnecting, two or more adjacent pads that come into contact to form a conductive path.

Solder Wick : A band of wire removes molten solder away from a solder joining or a solder bridge or just for desoldering.

Step-and-Repeat : The successive exposure of a single image on order to produce a multiple-image production master. Also used in CNC programs.

Stuff : Components are attached and soldered to a printed wiring board. Often done by an assembly house.

Sub-Panel : A group of printed circuits arrayed in a panel and handled by both the board house and the assembly house as though it were a single printed wiring board. The sub-panel is usually prepared at the board house by routing most of the material separating individual modules leaving small tabs.

Surface Mount : Surface mount technology. Components are soldered to the board without using holes. The result is higher component density, allowing smaller PWBs. Abbreviated SMT.

Temperature Coefficient (TC) : The ratio of a quantity change of an electrical parameter, such as resistance or capacitance, of an electronic component to the original value when temperature changes, expressed in %/ºC or ppm/ºC.

Test Point : A specific point in a circuit board used for specific testing for functional adjustment or quality test in the circuit-based device.

Testing :A method for determining whether sub-assemblies, assemblies and/or a finished product conform to a set of parameter and functional specifications. Test types include: in-circuit, functional, system-level, reliability, environmental.

Turnkey : A type of outsourcing method that turns over to the subcontractor all aspects of manufacturing including material acquisition, assembly and testing. Its opposite is consignment, where the outsourcing company provides all materials required for the products and the subcontractor provides only assembly equipment and labor.

Trace : Segment of a conductor route or net.

Track : Trace.

UL : Underwriter's Laboratories. A popular safety standard for electrical devices supported by many underwriters.

Via : A plated-through hole used for interconnection of conductors on different sides or layers of a PCB.

Wave Soldering : A manufacturing operation in which solder joints are soldered simultaneously using a wave of molten solder.