MIL-PRF-39035 Resistor, Variable, Nonwirewound \(Adjustment Type\), Nonestablished Reliability, And Established Reliability, General Specification ForThis specification covers the general requirements for nonestablished reliability \(non-ER\) and established reliability \(ER\), multiturn lead-screw actuated, and single-turn, nonwirewound, variable resistors with a contact bearing uniformly over the surface of the entire resistive element, when positioned by an actuator. These resistors are capable of full-load operation \(when the maximum resistance is engaged\), at a maximum temperature of 150 Degrees C, with a resistance tolerance of ??10 percent. The ER resistors will have life failure rate levels ranging from 1.0 to 0.001 percent per 1,000 hours \(see 1.2.1.5\). These failure rate levels are established at a 60 percent confidence level maintained at 10 percent producer\'s risk on the basis of the life tests.

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MIL-PRF-39035E

APPENDIX A

TABLE A-II. Extension of qualification between product levels.

Product level

Product

designator

level

C, M

C, M, P

C, M, P, R

A.5. SOLDER DIP (RETINNING) LEADS

A.5.1 Solder dip (retinning) leads (not applicable to terminal L). The manufacturer (or his authorized category B or

C distributor) may solder dip/retin the leads of product supplied to this specification provided the solder dip process

(A.5.2) or an equivalent process has been approved by the qualifying activity.

A.5.2 Qualifying Activity Approval. Approval of the solder dip process will be based on one of the following options:

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.

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

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

manufacturer's 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 (or hermetic seal test if the device is hermetically sealed). No defects are

allowed.

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