MIL-PRF-49465 Resistor, Fixed, Metal Element, Power Type, Very Low Resistance Values, General Specification ForThis specification covers the general requirements for power type, low value \(1 ohm and below\), fixed resistors \(2 terminal and 4 terminal\) for use in electrical, electronic, communications, and associated equipment. Included are precision resistors of ??1 percent, ??3 percent, and ??5 percent initial resistance tolerances with power ratings ranging from 3 watts to 5 watts at +25 degrees C derated to 0 power at +275 degrees C.

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MIL-PRF-49465C

3.6 Voltage rating. Each resistor element shall have a rated dc continuous working voltage or an approximate

sine-wave root mean square (rms) continuous working voltage corresponding to the wattage (power) rating, as

determined from the following formula:

E = PR

Where: E = Continuous rated dc or rms working voltage in volts.

P = Rated wattage in watts.

R = Nominal resistance in ohms.

In no case shall the rated voltage be greater than the applicable maximum voltage (see 3.1).

3.7 Current rating. Resistors that have a maximum current rating shall be as specified (see 3.1).

3.8 DC resistance. When resistors are tested as specified in 4.8.2, the dc resistance shall be within the specified

tolerance of the nominal resistance (see 3.1).

3.8.1 Resistance value deviations. All maximum deviations as specified in this section are to be considered

absolute limits with the exception of the contact resistance adjustments.

3.9 Solderability. When resistors are tested as specified in 4.8.3, they shall meet the criteria for wire lead terminal

evaluation in the test method.

3.10 Resistance to solvents. When resistors are tested as specified in 4.8.4, there shall be no evidence of

mechanical damage and the markings shall remain legible.

3.11 Thermal shock. When tested as specified in 4.8.5, resistors shall not change in resistance in excess of �(0.2

percent +.0005 ohm), nor show any evidence of mechanical damage. There shall be no change in resistor enclosure

or other part that will result in degradation in performance.

3.12 Resistance temperature characteristic. When resistors are tested as specified in 4.8.6, the resistance

temperature characteristic between -55OC and +275OC shall not exceed the value as specified (see 3.1).

3.13 Low temperature storage. When resistors are tested as specified in 4.8.7, there shall be no evidence of

mechanical damage. The change in resistance between initial and final resistance measurements at +25OC �5OC

shall not exceed �(0.2 percent + .0005 ohm).

3.14 Short time overload. When resistors are tested as specified in 4.8.8, there shall be no evidence of arcing,

burning, or charring; and the change in resistance shall not exceed �(0.5 percent + .0005 ohm).

3.15 Dielectric withstanding voltage. When resistors are tested as specified in 4.8.9, the leakage rate shall not

exceed 500 microamperes; there shall be no evidence of flashover, mechanical damage, arcing, or insulation

breakdown, and the change in resistance shall not exceed �(0.1 percent + .0005 ohm).

3.16 Insulation resistance. When resistors are tested as specified in 4.8.10, the insulation resistance shall not be

less than 1,000 megohms.

3.17 Moisture resistance. When resistors are tested as specified in 4.8.11, there shall be no evidence of

mechanical damage, and the change in resistance shall not exceed �(0.2 percent + .0005 ohm). In addition, the

dielectric withstanding voltage shall be as specified in 3.15, and the insulation resistance shall be 100 megohms

minimum.

3.18 Terminal strength. When resistors are tested as specified in 4.8.12, there shall be no evidence of breaking or

loosening of terminals from the resistor form, chipping of enclosure, or other evidence of mechanical damage. The

change in resistance shall not exceed �(0.1 percent + .0005 ohm).