-Q-

Quantum ~ The smallest amount of a physical quantity that can exist independently, especially a discrete quantity of electromagnetic radiation.

Quiescent ~ At rest, not changing.  For an amplifier the term is used to describe a condition with no active input signal.

-R-

Rail ~ Either pole of a power source used to supply current to an electronic device; one is positive and one is negative. (i.e. VCC, VSS, +5V, -5V, +3.3V, GND)

Rat-bite ~ A method of implementing a breakaway tab to the printed circuit board.

Reactance ~ A form of opposition that electronic components exhibit to the passage of alternating current (AC) due to of capacitance or inductance.

Rectifier ~ Circuitry transforming AC into DC, usually consisting of 4 diodes (aka bridge rectifier).

Regulator ~ An electronic device which maintains a constant voltage or current output.

Reluctance ~ Resistance to the flow of magnetic lines of force.

Resistance (R) ~ The measurement of how much a resistor impedes the flow of electrons in an electrical or electronic circuit. Resistance is measured in ohms.

Resonance ~ Circuit condition that occurs at the frequency where inductive reactance (XL) equals capacitive reactance (XC).

Reverse Bias ~ A condition where an electrical device needing DC electricity is intentionally or by accident, reversing the inbound power, usually causing the component to be inactive.

Root Mean Square (RMS) ~ Root Mean Square. The real peak value of an AC voltage, which is U * square root of 2, abbreviation Vrm.

-S-

Saturation ~ Condition in which a further increase in one variable produces no further increase in the resultant effect. In a bipolar junction transistor, the condition when the emitter to collector voltage is less than the emitter to base voltage.

Schematic ~ A drawing that shows the electronic functionality and connectivity as well as the values of all the components in an electronic device or circuit.

Scoring ~ The panels are precision cut through both sides of the panel to a preset depth. The panels remain rigid for assembly but are ready for breaking into individual circuits.

Secondary Side (SS) ~ The opposite side to the primary side, usually the least populated or less complex side of a printed circuit board.

Semiconductor ~ A material that is neither a good conductor of electricity (like copper) nor a good insulator (like rubber). The most common semiconductor materials are doped silicon and germanium.

Signal ~ A generated electrical impulse that is a change in voltage to trigger or monitor an event.

Silicon ~ (Si) Non metallic element (atomic number 14) used in pure form as a semiconductor.

Silkscreen ~ The legend or markings screened on to a printed circuit board.  The silkscreen usually includes component outlines, reference designators, polarity indicators, pin one markings, part numbers, company name, copyright info.

Sine-wave ~ Wave whose amplitude is the sine of a linear function of time.  It is plotted on a graph that plots amplitude against time or radial degrees relative to the angular rotation of an alternator.

Single Inline Package (SIP) ~ Package containing several electronic components (generally resistors) with a single row of connecting pins.

Skew ~ The time difference between the arrival of the signal at one gate and the arrival of the same signal at another gate.

Slew Rate ~ The maximum rate at which the output voltage of an op-amp can change.

Solder ~ Solder is used to make a conductive contact between wires or between component and printed circuit board. It is made of tin (Sn) and lead (Pb) and contains a rosin core, which makes the solder flow more easily.

Soldermask, Dry Film ~  A photo-imageable dry film protective soldermask allowing a minimum 0.003 to 0.005 inch clearance on each side of the pad.

Soldermask, Liquid Photo Imageable (LPI) ~ The standard protective soldermask for SMT applications. It requires a clearance of 0.001 to 0.0015 inch on each side of the pad. This is very attractive for fine pitch applications, because it is a thin coating. 

Solder Mask, Wet Film ~ A screenable protective solder mask. Wet film works well on through hole and sparsely populated SMT printed circuit boards.

Soldermask Over Bare Copper (SMOBC) ~ Process of applying a protective soldermask coating to the printed circuit board.

Solderpaste ~ A liquid paste which is screened onto the surface mount printed circuit board lands prior to the components being installed.  The assembly is then heated with infrared or vapor phase methods to solidify the paste to a solder joint.

Square-wave ~ Wave that alternates between two fixed values for an equal amount of time.

Standard Cell ~ Predefined circuit elements used to create a custom or semi-custom integrated circuit.

Stencil ~ A thin sheet of brass or stainless steel with openings that match the land pattern of the printed circuit board.  During printing, adhesive or solder paste is forced through these openings onto the printed circuit board.

Substrate ~ Electrically active material on which a micro-electronic device is built (silicon or passive alumina ceramic).

Surface Mount Technology (SMT) ~ A manufacturing process that attaches components on the surface of the printed circuit board, rather than inserting components into plated through hole.

System In Package (SIP) ~ A hybrid or custom electronic package containing an entire electronic system, microprocessor, memory, logic, and interface circuitry.  It rivals the SOC or system On Chip, which is much more expensive and has a longer design time.

-T-   

Tantalum Capacitor ~ Electrolytic capacitor having a tantalum foil anode. Able to have a large capacity in a small package.

Teardrop ~ A process for strengthening the connections between a printed circuit board pads and track/trace.  A funnel shape polygon is added to the pad inline with the track to prevent drilling breakout on pads with small annular rings (< .005").

Terabyte (TB) ~ A number equivalent to 2 to the 40th power (1,099,511,627,776) bytes. This is approximately 1 trillion bytes, or 1024 gigabytes.

Tenting ~ The process of covering the vias with soldermask.

Thermal Relief ~ A wagon wheel-shaped relief pad etched in the copper of a printed circuit board power or ground plane.  It restricts heat flow to the land or pad for sufficient soldering conditions.

Time constant  (t) ~ Time required for a capacitor in an RC circuit to charge to 63% of the remaining potential across the circuit. Also time required for current to reach 63% of maximum value in an RL circuit. Time constant of an RC circuit is the product of R and C. Time constant of an RL circuit is equal to inductance divided by resistance.

Thermistor ~ This is a special type of resistor. The resistance of all resistors changes slightly as they get hotter. Thermistors are usually made so that their resistance falls noticeably as the temperature around them rises.

Thru-Hole ~ A chip packaging technology requiring holes in the PCB through which component pins were inserted and soldered on the reverse side.

Toe ~ The end of a formed electronic package pin.

Trace ~ A line or "wire" of conductive material such as copper, silver, or gold on the surface of or sandwiched inside a printed circuit board.

Transistor ~ An electrically controllable semiconductor resistor.  It has three terminals Collector, Emitter, and Base.  When the appropriate bias is applied to the Base, current flows between Collector and Emitter.

Transformer ~ The purpose of a transformer is to convert one AC voltage to another AC voltage.

Transmission Line ~ Conducting line used to transmit signal energy between two points.

Triac ~ An electronic device, similar to an SCR, which conducts current in both directions.

 

These definitions were compiled from the internet and CADKraft Engineering assumes no liability in their accuracy nor their completeness.