GLOSSARY of Printed Circuit Design and Manufacturing
This glossary has key terminology in use in PCB design and manufacturing, with a smattering of electronics. The definitions were chosen so that their context would likely apply to reading material encountered by a PCB designer. Therefore, many of these terms will have other meanings not given here. It is recommended by scholars that you also clear up the non-technical definitions in regular dictionaries. There are such dictionaries recommended below.
This collection of terms came about as I, a PCB designer, ran across words and acronyms in my field for which meanings were hard to find. As I tracked them down, I made them part of this glossary. If you are a PCB designer, then this glossary could be a good place to start when you find a need to look up the meanings of words related to printed circuits or electronics.
Alphabetizing
Method
Terms that begin with a symbol or a digit are placed in the SYMBOLS page. Terms that contain digits within them are alphabetized as if the numeric
characters were spelled in English.
Terms with two or more words are alphabetized "dictionary style." They are alphabetized as though the spaces between the terms have been removed. If there are other characters in the term, such as a slash (/), dash (-) or plus sign (+), these are treated the same as spaces and ignored for the purpose of alphabetizing.
Modern Dictionary of Electronics
by Rudolf F. Graf
This is the best, most usable dictionary for electronics, because its
definitions help you grasp the terms and therefore the subject. Lesser
dictionaries define electronics terms with even more difficult technical
jargon, leading one into endless"word chains." Not this one.
You can
buy the Modern Dictionary of Electronics new or used
via the Internet.
Citation:
Graf, Rudolf F. Modern Dictionary of Electronics. Newnes, 1999.
The Random House Dictionary of the English Language, Unabridged, 2nd Edition
You need a big, comprehensive dictionary. Get this one. Despite being a big
dictionary,
The Random House
has great definitions, quick to grasp.
Although out of print, as of 2022 you could still buy a great used copy online for $40 including shipping or possibly for much less. Two versions are available of the 2nd Edition, Unabridged:
I have no idea what the difference is for the deluxe edition, but there seem to be fewer copies of it available in 2020 than the regular edition. I'm sure they both have the same set of definitions. My copy has both ISBNs listed in the front matter, and it is the regular edition.
Citation:
Flexner, Stuart Berg, and Leonore Crary Hauck, editors. The Random House Dictionary of the English Language. Unabridged, 2nd Edition, Random House, 1987.
tab terminal — (aka "quick disconnect" or "blade connector." or "AMP FASTON terminal.") These are widely used in electronic and electrical equipment, and compatible terminals are manufactured by many different vendors.
tactile switch — A push-button switch with a very low actuation force that is momentary (terminals are normally open and are closed only while the button is being pushed). The actuation force is low enough that merely touching the button (actuator) with ones finger will close the terminals.
tape automated bonding — (TAYP aw-tuh-MAY-tid BAHN-ding) Pronunciation Keynoun [Assembly]
Tape automated bonding (TAB) is a microelectronics packaging technique that uses a thin, flexible tape with pre-etched copper traces to connect integrated circuits (ICs) to a substrate or printed circuit board (PCB). This method enables high-density interconnections, reducing the space required for component mounting.
TAB is used to facilitate efficient and reliable attachment of semiconductor chips to circuit substrates, especially in applications requiring fine-pitch connections. It was developed as an alternative to traditional wire bonding to improve manufacturing automation, yield, and electrical performance.
The effect of TAB is an increase in production efficiency and electrical performance in high-density electronics. It enables miniaturization, enhances thermal dissipation, and reduces inductive parasitics compared to wire bonding. However, it requires specialized processing equipment and precise alignment techniques.
Tape automated bonding can be influenced or modified by adjusting the tape material, refining the bonding process (e.g., using thermocompression or thermosonic bonding), or incorporating advanced encapsulation techniques to enhance reliability and durability.
The origin of TAB dates back to the 1960s and 1970s when microelectronics packaging evolved to accommodate increasing circuit complexity. It gained prominence in industries such as aerospace, telecommunications, and consumer electronics, where miniaturization and high-performance interconnections are critical. The name "tape automated bonding" reflects its use of reel-to-reel tape in automated assembly processes.
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.
TEC — noun ThermoElectric Cooler, a type of active heat sink used on CSP's. Also called Peltier thermoelectric cooler, it depends for its function on the
Peltier effect
.
tented via — a via with dry film solder mask completely covering both its pad and its plated-through hole. This completely insulates the via from foreign objects, thus protecting against accidental shorts, but it also renders the via unusable as a test point. Sometimes vias are tented on the top side of the board and left uncovered on the bottom side to permit probing from that side only with a test fixture.
terminal — A point of connection for two or more conductors in an electrical circuit; one of the conductors is usually an electrical contact, lead or electrode of a component.
terminal block — A type of
header to which wires are attached directly instead of by means of a connector plug. Each wire is inserted in a hole in the terminal block , and then anchored by means of a screw.
test coupon — An area of patterns and holes located on the same fabrication panel as the actual PCB, but separate from the electrical circuits and outside the board outline(s). It is designed to reflect the technology used on the PCB, such as smallest plated-through hole size, any blind or buried vias, etc. It is cut away from the panel and can be embedded in a clear plastic to prepare it for
destructive testing.
thermal pad — A heat-transfering plane of metal within a packaged integrated circuit to which a
die is attached. Although a thermal pad is internal to the IC package, it is exposed on the bottom of the package in order to carry heat into the PCB. Therefore, a land should be provided for soldering it to the PCB. It typically carries no digital or analog signal but would usually be connected to ground so that heat could be efficiently transferred to the built-in heat sinks of ground planes in the PCB.
For information on PCB design of footprints with thermal pads, see in this glossary
exposed paddle.
through-hole — (Of a component, also spelled "thru-hole"). Having pins designed to be inserted into holes and soldered to pads on a printed board. Contrast with
surface mount.
Through-Hole Technology. Electronic components mounted on a circuit board by passing their leads through holes in the board and usually soldering them in place.
tin-silver-copper — Aka
SAC (SnAgCu). A lead-free (Pb-free) alloy commonly used for electronic solder. The tin-silver-copper alloy has been the prevailing alloy system used to replace tin-lead because it is near eutectic, with adequate thermal fatigue properties, strength, and wettability.[1] Lead-free solder is gaining much attention as the environmental effects of lead in industrial products is recognized, and as a result of Europe's RoHS legislation to remove lead and other hazardous materials from electronics. Japanese electronics companies have also looked at Pb-free solder for its industrial advantages.
tombstoning — [PCB assembly] "A surface mount passive component, like a resistor or a capacitor, that partially lifts from a pad on one end. As your component stands on end like it’s rising from the dead, it ends up looking like a tombstone in the graveyard of what is now a defunct PCB design with an open circuit."
Citation:
Sattel, Sam.: Autodesk, 26 June 2017, What Is PCB Tombstoning?.
top view — [PCB assembly and PCB design] Of a component: This is the viewpoint of looking down on the part from the side of the board from which it is inserted or placed.
[Electrical Circuits] The topology of an electronic circuit is the form taken by the network of interconnections of the circuit components. Different specific values or ratings of the components are regarded as being the same topology. Topology is not concerned with the physical layout of components in a circuit, nor with their positions on a circuit diagram. It is only concerned with what connections exist between the components. There may be numerous physical layouts and circuit diagrams that all amount to the same topology. Wikipedia Topology (electrical circuits)
[Networking] Physical topology is the placement of the various components of a network, including device location and cable installation, while logical topology illustrates how data flows within a network, regardless of its physical design. Distances between nodes, physical interconnections, transmission rates, or signal types may differ between two networks, yet their topologies may be identical.
TQFP — Thin Quad Flat Pack. Essentially the same as a QFP except low-profile, that is, thinner.
A thin quad flat pack (TQFP) provides the same benefits as the metric QFP, but is thinner. Regular QFPs are 2.0 to 3.8 mm thick depending on size. TQFP packages range from 32 pins with a 0.8 mm lead pitch, in a package 5 mm by 5 mm by 1 mm thick, to 256 pins, 28 mm square, 1.4 mm thick and a lead pitch of 0.4 mm.
Source: Charles Cohn, Charles A. Harper (ed) Failure-free integrated circuit packages, McGraw-Hill, 2005 ISBN 0-07-143484-4 at Amazon.com pages 22-28.
trace pitch — the distance between the center lines of two or more equal-width traces. This is an important quantity to a PCB designer who is routing a board on a specific grid and especially differential pairs. The trace pitch equals the trace width plus the air gap or spacing between the traces. If routing differential pairs with edge-coupled impedance control, the PCB designer can prevent downstream problems by using a trace pitch that fits on a convenient grid and gives leeway for the board house to re-calculate the edge-coupled impedance based on their material qualtities. The board house should be able to globally change the trace width (and thus spacing) without any re-routing and without introducing any spacing errors. The grid that works best for a 1mm-ball-pitch BGA is 0.1mm, with the trace pitch set at 0.2mm. The trace width can be anything less than or equal to 0.1mm that adds to the spacing to make 0.2mm. In calculating controlled edge-coupled impedance, keep the trace pitch constant, trying various trace widths and spacings that add up to this.
[PCB Layout] A segment of a line, whether copper trace (printed wire) or silkscreen line.
[Altium Designer] Any line or trace in a PCB CAD file that does not curve is called in Altium Designer a track. Parameters can be width and layer and net (or No Net if not connected). In Altium Designer's PCB menus, to draw a track in silkscreen, make the "Top Overlay" layer active and use Place -> Line. For copper, make one of the copper layers active and use Place -> Track.
transducer (tranz-DOO-ser) — noun. [Sensors & Actuators]. An electronic device that converts
energy from one form to another, enabling a signal to be processed or transmitted. Common examples include
microphones, loudspeakers, thermometers, and antennae. In PCB design, examples familiar to designers include
opto-isolators, LEDs, and components that utilize the piezoelectric effect, such as pressure sensors. A transducer is
a physical interface that bridges different energy domains, converting energy (such as electrical, mechanical, or
light energy) into a usable form for further processing or measurement. Its purpose is to enable communication between
a system's electrical circuitry and the external environment, often in the form of sensing or actuation.
The existence of a transducer is driven by the need to measure, sense, or influence physical parameters such as sound,
light, pressure, or temperature, and convert these into electrical signals (or vice versa) to allow them to be
monitored or manipulated in electronic systems.
When a transducer is employed, it allows a system to perform tasks such as data acquisition, control, or signal
processing by providing accurate measurements or actuation capabilities, which are essential for proper operation in
systems like audio equipment, medical devices, or automated controls.
A transducer's efficiency or accuracy can be affected by factors such as interference, temperature, aging, or
mechanical wear. These devices can be adjusted or improved through calibration, shielding, or upgrading their
material components to increase precision and longevity.
From Latin transducere/traducere "lead across, transfer, carry over," from trans "across, beyond" + ducere "to lead"
transmission line — A signal-carrying circuit with controlled electrical and magnetic characteristics used to transmit high-frequency signals. "High frequency" can refer to electronic signals operating at or above 100MHz.
transponder — A wireless communications, monitoring, or control device that picks up and automatically responds to an incoming signal. The term is a contraction of the words transmitter and responder. Transponders can be either passive or active.
tranzorb — (slang) A circuit protection device, protecting the circuit from high voltage spikes, such as could be received by a lightning hit. A tranzorb consists of a varistor (variable resistor or voltage dependent resistor (VDR)) used as a transient voltage suppressor (TVS). A varistor has very high resistance at low voltage and very low resistance at high voltage, thus a tranzorb will allow a large current to flow through it when voltage is high and only very small leakage current to flow when voltage is low. To protect a circuit, the tranzorb can be placed electrically between the power supply and the ground, or across an input line and ground if the input is from a wire exposed to possible lightning hits. If lightning strikes the line, the voltage spike will be transmitted harmlessly to ground (one hopes).
Tranzorbs can be either polar (unidirectional) or bipolar (bidirectional.)
The unipolar version is actually an "avalanche diode." But this is probably more than you wanted to know about tranzorbs. (If not see
"varistor" at Wikipedia.)
TSSOP — Thin Shrink Small Outline Package, a dual in-line small outline package. Thin is a relative term and for the small outline packages commonly implies a package height of 1.2 mm or less. TSSOP's commonly have a lead pitch of 0.5 to 0.65mm. Example of IPC name: SOP65P640X120-8N Example of John Walt Childers' name: TSSOP8_SOP65p640x120-8n
TTL — Transistor-Transistor Logic. Also called multiple-emitter transistor logic. A widely used form of semiconductor logic. Its basic logic element is a multiple-emitter transistor. TTL is characterized by fairly high speed and medium power dissipation.
[Graf, Rudolf F. Modern Dictionary of Electronics. Newnes, 1999]
