RESISTOR GLOSSARY

Derating －
At ambient temperatures higher than the maximum specified for full rated power, a reduced amount of power is allowable in the resistor. The allowable amount is shown in derating curves which normally end at zero power at the maximum surface temperature applicable to the resistor type.

Derating Curve －
The curve that expresses the relation between the ambient temperature and the maximum value of continuously loadable power at its temperature, which is generally expressed in percentage.

Dielectric Strength －
The maximum voltage of the dielectric or insulation of a resistor or potentiometer applied between the case and all terminals connected to each other, without exceeding a specified leakage current.

Dielectric Withstanding Voltage －
A.C. voltage (commercial frequency effective value) that can be applied to a designated spot between the electrode and the outer coating for a minute in the dielectric withstanding voltage test. (JIS C 5201-1 4.7)

Discrete Resistors －
Resistors that have a single resistive element per component.

Film Resistor －
A fixed resistor relying on film properties of resistance material rather than bulk properties.

Fixed Resistors －
Resistors that have a specified resistance value that does not change.

Flip Chip Resistor －
An unencapsulated resistor chip on which bead-type leads terminate on one face to permit “flip” (face down) mounting of the resistor chip by contact of the leads with interconnective circuitry.

Frequency －
The number of cycles per unit of time of a reoccurring event, wave or oscillation. Usually measured in cycles per second, known as Hertz.

Hot-Spot Temperature －
The maximum temperature measured on the resistor due to both internal heating and the ambient operating temperature.

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 measured in ohms (Ω).

Inductance －
The property of a wirewound resistor that causes voltage to be set up because of a change in current through the device.

Insulation Resistance －
The DC resistance measured between all terminals connected together and the case, exterior insulation, or external hardware.

Insulator －
A material along which an electrical charge (current flow) cannot readily pass. Used to keep conductors apart or to prevent the escape of electricity.

Linearity －
The relationship of actual electrical output to the theoretical output when the theoretical output is a straight-line function.

Low Profile －
Components designed with “lower than standard heights,” to save space and allow clearance when mounted on PCBs.

Maximum Overload Voltage －
Specifications given herein may be changed at any time without prior notice. Please confirm technical specifications before you order and/or use. The maximum value of voltage capable of being applied to resistors for five seconds in the overload test (JIS C 5201-1 4.13). Typically the applied voltage in the short time overload test shall be 2.5 times larger than the rated voltage. However, it shall not exceed the maximum overload voltage.

Maximum Working Voltage －
The maximum value of D.C. voltage or A.C. voltage (commercial frequency effective value) capable of being applied continuously to resistors or element. However, the maximum value of the applicable voltage is the rated voltage at the critical resistance value or lower.

Megohm (MΩ) －
One million ohms.

Metallization －
A film pattern (single or multilayer) of conductive material deposited on a substrate to interconnect electronic components, or the metal film on the bonding area of a substrate which becomes a part of the bond and performs both an electrical and a mechanical function.

Ohm’s Law －
The formula used to determine the three basic building blocks of a circuit:
volts (V), current in amps (I), resistance in ohms (R); V = I x R.

Output －
The voltage, current, or power developed by a circuit in response to an input.

PPM －
Parts per million. The terminology used when describing the temperature coefficient.

Passive Components －
Components such as capacitors and resistors, which have no gain characteristics.

Paste/Ink －
Screenable, thick film material composed of metals, oxides, and glasses in an organic vehicle which when fired, produces a circuit element such as a resistor or conductor.

Rated Ambient Temperature －
The maximum ambient temperature at which resistors are capable of being used continuously with the prescribed rated load (power). The rated ambient temperature refers to the temperature around the resistors inside the equipment, not to the air- temperature outside the equipment.

Rated Power －
The maximum value of power, which can be continuously loaded to a resistor at a rated ambient temperature. Please confirm beforehand that there is such a case in a network that rated power per package as well as per element is specified.

Rated Voltage －
The maximum value of D.C. voltage or A.C. voltage (commercial frequency effective value) capable of being applied continuously to resistors at the rated ambient temperature. Rated voltage shall be calculated from the following formula. However, it shall not exceed the maximum working voltage.
Rated Voltage (V) = √Rated Power (W) × Nominal Resistance Value(Ω)

Reactance －
Opposition to the flow of alternating current offered by capacitance, inductance or both. Both reactances are measured in ohms, and symbolized by the variable x.

Resistance (unit Ohm, Ω) －
A specific property of a material depends on its molecular structure, size and temperature and in a circuit, acts to oppose an applied voltage and limit the current flowing into the circuit. Resistance is measured in ohms.

Resistive Products －
A broader term that describes components whose primary function is to introduce resistance into the circuit.

Resistor Element －
A continuous, unbroken length of resistive material without joints, bonds or welds except at the junction of the element and the electrical terminals connected to each end of the element, or at an intermediate point.

Resistor －
A basic component that introduces resistance in electrical and electronic circuits.

Resistor Tolerance －
The permissible deviation of the manufactured resistance value (expressed in percent) from the specified nominal resistance value at standard (or stated) environmental conditions.

Screen Print －
The process of printing a network pattern of thick-film ink or paste onto a substrate by means of a squeegee applied to a photo-etched wire-mesh “silk screen” or metal mask.

SMT/SMD －
Surface-mount technology/surface-mount device.

Stability －
The overall ability of a resistor to maintain its initial resistance value over extended periods of time, when subjected to any combination of environmental conditions and electrical stresses.

Standard Resistance Value －
The resistance value tabulated by a decade chart is specified in the applicable military specification. Resistance values not listed in the chart for the appropriate tolerances are considered as non-standard for that specification.

Surface Mount －
See SMT/SMD.

Temperature Coefficient of Resistance (TCR) －
The rate of change in resistance value per 1°C in the prescribed temperature within the range of resistors operating temperature shall be expressed in the following formula:
T.C.R. (ppm/°C) =(R-Ro)/Ro × 1/(T-To) × 10⁶
R: Measured resistance(Ω) at T °C
Ro: Measured resistance(Ω) at To °C
T: Measured test temperature(°C)
To: Measured base temperature(°C)

Tolerance －
Usually applies to the extent from which the actual resistance reading may vary from the rated resistance value when it is actually tested.

Tracking －
The inherent capability of resistors from the same formulation and screened onto the same substrate to exhibit similar performance characteristics (e.g., drift, TCR).

Voltage (unit Volt, V) －
The electromotive force trying to move electrons from negative to positive; the “pressure” in the circuit.

Watt (W) －
Practical unit of electrical power. One watt is the power delivered when a current of one ampere is driven by one volt.

Wirewound Resistor －
A resistor in which the resistance element is a length of high-resistivity wire or ribbon, wound onto an insulating core, then encapsulated in a vitreous enamel, silicone or cement compound.

Zero Ohm Resistors －
Products that look like resistors, but actually have no resistance and instead perform as jumpers.