PCB glossary T-Z

PCB Glossary starting with T

TAB: Tape Automated Bonding.

Tape Automated Bonding: Tape Automated Bonding is a specialized assembly-process technology, which involves the application of components onto a circuit board using temperature and pressure.

TDR: Time Domain Reflectometer, a device which a board house can use for measuring characteristic impedance of a conductor on a printed board, thus insuring an accurate build for controlled impedance.

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.

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

Tenting: The covering of holes in a printed board and the surrounding conductive pattern with a dry film resist.

Terminal: A point of connection for two or more conductors in an electrical circuit; one of the conductors is usually an electrical contact or lead of a component.

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

Test Fixture: A device that interfaces between test equipment and the unit under test.

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.

TG - (Glass transition temperature): The point at which rising temperatures cause resin inside the solid base laminate to start to exhibit soft, plastic-like symptoms. This is expressed in degrees Celsius (°C).

Thermal pad: Pad of a special form used when it is connected to copper pours. Thermal pads improve solderability of the joint, reducing the chance of a so called "cold solder joint"

Thief: An extra cathode placed as to divert to itself some of the current from portions of the board which otherwise would receive too high a current density.

Thin film: A film of conductive or insulating material, usually deposited by sputtering or evaporation, that may be made in a pattern to form electronic components and conductors on a substrate or used as insulation between successive layers of components.

Three-Dimensional Laser Paste: Three-Dimensional Laser Paste is a volumetric inspection method that utilizes a microscope with lasers.

Through-hole: A drilled hole in the board, usually for mounting purposes.

Tooling Holes: The general term for holes placed on a PCB or a panel of PCBs for registration and hold-down purposes during the manufacturing process.

Trace (or Route,track): A layout or wiring of an electrical connection.

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.

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

PCB Glossary starting with U

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

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

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

PCB Glossary starting with V

Via: A plated through hole that is used as an inter-layer connection, but doesn’t have component lead or other reinforcing material inserted in it.

Void: The absence of any substances in a localized area.

PCB Glossary starting with W

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

Wet solder mask: Applied by means of distributing wet epoxy ink through a silk screen, a wet solder mask has a resolution suitable for single-track design, but is not accruate enough for fine-line design.

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

WIP—Work In Progress: [Usage at Golden Gate Graphics: wip is used as the extension of the name of a folder or sub-directory which groups data in temporary storage locations for current "work in progress." Any folders beneath the .WIP folder in the directory structure would be named for the software, company and job in that order. Eg: pclayout.wip/Cadstar/AcmeInc/A2Dboard ]

Wire: Besides its usual definition of a strand of conductor, wire on a printed board also means a route or track .

Wire bonding: The method used to attach very fine wire to semiconductor components (dice) to interconnect these components with each other or with package leads. The wires might be 1 to 2 mils in diameter and made of aluminum containing 1% silicon.

Wire wrap area: A portion of a board riddled with plated-through holes on a 100-mil grid. Its purpose is for accepting circuits which may be found necessary after a PWB has been manufactured, stuffed, tested and debugged.

PCB Glossary starting with X

X-Ray Laminography: X-Ray Laminography is an inspection method, which utilizes x-rays to view thin layers of a circuit board.