MIL-PRF-39005 Resistors, Fixed, Wirewound \(Accurate\), Nonestablished Reliability, Established Reliability, General Specification ForThis specification covers the general requirements for nonestablished reliability \(non-ER\), established reliability \(ER\), accurate, wire-wound, fixed resistors that have a maximum resistance tolerance of 1 percent and a high degree of stability with respect to time under specified environmental conditions. The resistors are capable for continuous full-load \(or voltage\) operation at any ambient temperature up to 125??C, and when derated, up to 145??C \(see 6.5\). They are not capable for application where the alternating current \(ac\) characteristics are of critical importance. ER resistors have life failure rates \(FR\) ranging from 1.0 percent to 0.001 percent per 1,000 hours \(see 1.2.1.5\). These FR are established at 60-percent confidence level on the basis of the life tests. The FR, identified by the appropriate symbol, is referred to operation at full rated voltage and temperature.

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MIL-PRF-39005G

3.17 Vibration, high frequency. When resistors are tested as specified in 4.8.13, there shall be no

evidence of mechanical or electrical damage. The change in resistance shall not exceed �0.01 percent

for resistance values of 10 ohms and above, and �(0.01 percent +0.01 ohm) for values less than 10

ohms.

3.18 Resistance temperature characteristic. When resistors are tested as specified in 4.8.14, the

resistance temperature characteristic, referred to an ambient temperature of 25�C, shall not exceed the

value specified in table VI.

TABLE VI. Maximum RTC.

Resistance

Percent/�C

Parts/million/�C

Less than 1 ohm

�0.009

�90

1 ohm to less than 10 ohms

�0.003

�30

10 ohms to less than 100 ohms

�0.0015

�15

100 ohms and above

�0.0010

�10

3.19 Low temperature storage. When resistors are tested as specified in 4.8.15, there shall be no

evidence of mechanical damage. The change in resistance between initial and final measurements at

25�C �5�C shall not exceed �0.01 percent for resistance values of 10 ohms and above, and �(0.01

percent +0.01 ohm) for values less than 10 ohms.

3.20 Low temperature operation. When resistors are tested as specified in 4.8.16, there shall be no

evidence of mechanical damage. The change in resistance between initial and final measurements at

25�C �5�C shall not exceed �0.01 percent for resistance values of 10 ohms and above, and �(0.01

percent +0.01 ohm) for values less than 10 ohms.

3.21 Life.

3.21.1 Qualification. When resistors are tested as specified in 4.8.17, there shall be no evidence of

mechanical damage to the resistance element, coating, or enclosure. The change in resistance between

the initial and any succeeding measurement shall not exceed �(0.1 percent +0.01 ohm).

3.21.2 FRL determination (extended FR test) (ER only). When resistors are tested as specified in

4.8.17, there shall be no evidence of mechanical damage to the resistance element, coating, or

enclosure. The change in resistance between initial and any succeeding measurement shall not exceed

�(0.2 percent +0.01 ohm). This single failure criterion shall be applicable as a parallel requirement to all

measurements during the life test for purposes of determining FRL qualification.

3.22 Fungus. All external materials shall be nonnutrient to fungus growth or shall be treated to retard

fungus growth. The manufacturer shall certify that all external materials are fungus resistant, or shall

perform the test specified in 4.8.18. There shall be no evidence of fungus growth on the external

surfaces.

3.23 Resistance to solvents. When resistors are tested as specified in 4.8.19, there shall be no

evidence of mechanical damage and the markings shall remain legible.