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

APPENDIX A

A.5.2 Qualifying activity approval. Approval of the solder dip process will be based on one of

the following options:

a. When the original lead finish qualified was hot solder dip lead finish 52 of MIL-STD-1276

(NOTE: The 200 microinch maximum thickness is not applicable). The manufacturer shall

use the same solder dip process for retinning as is used in the original manufacture of the

product.

b. When the lead originally qualified was not hot solder dip lead finish 52 of MIL-STD-1276 as

prescribed in A.5.2a, approval for the process to be used for solder dip shall be based on

the following test procedure:

(1) Thirty samples of any resistance value for each style and lead finish are subjected to

the manufacturing solder dip process. Following the solder dip process, the resistors

are subjected to the dc resistance test (and other group A electricals). No defects are

allowed.

(2) Ten of the 30 samples are then subjected to the solderability test. No defects are allowed.

(3) The remaining 20 samples are subjected to the resistance to solder heat test followed

by the moisture resistance test.

(NOTE: Solder dip of gold plated leads is not allowed.)

A.5.3 Solder dip/retinning options. The manufacturer (or authorized category B or C distributor)

may solder dip/retin as follows:

a. After the 100 percent group A screening tests. Following the solder dip/retinning process,

the electrical measurements required in group A, subgroup 1, 100 percent screening tests

shall be repeated on 100 percent of the lot. (NOTE: The manufacturer may solder dip/retin

prior to the 100 percent electrical measurements of the group A, subgroup 1 tests.) The

percentage defective allowable (PDA) for the electrical measurements, shall be as for the

subgroup 1 tests.

b. As a corrective action, if the lot fails the group A solderability test. The lot may be retinned

no more than two times. The lot after retinning shall be 100 percent screened for group A

electrical requirements (dc resistance) and parts failing (lot not exceeding PDA for group A,

subgroup 1 (see 4.6.3.2.1)) these screens shall not be supplied to this specification, if

electrical failures are detected after the second retinning operation exceeding 1 percent of

the lot, the lot shall not be supplied to this specification..

c. After the group A inspection has been completed. Following the solder dip/retinning

process, the electrical measurements required in group A, subgroup 1, 100 percent

screening test shall be repeated on 100 percent of the lot. The PDA for the electrical

measurements shall be as for the subgroup 1 tests. Following these tests, the

manufacturer shall submit the lot to the group A solderability test as specified in 4.8.6.