MIL-STD-690-SUP Failure Rate Sampling Plans and ProceduresThis standard provides procedures for failure rate FR qualification, sampling plans for establishing and maintaining FR levels at selected confidence levels, and lot conformance inspection procedures associated with FR testing for the purpose of direct reference in appropriate military electronic parts established reliability ER specifications. Figures and tables throughout this standard are based on exponential distribution. Weibull distribution will be acceptable in certain components such as capacitors. Use of Weibull distribution for any component must be approved by the qualifying activity. This standard also provides guidance to specification writers in the use of this standard see appendix A and references material for users of ER parts.

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MIL-STD-690D

Lot number 1 . Lot size 1,000 . Record no. . Dates of production . Sample size 110 . Test temperature .

Type designation in lot Quantity in lot Quantity in sample

CLR25BD600UGM 500 55

CLR25BE400UGM 500 55

Sample

No.

Rating

(µf-V dc)

Designated

test time 1/

Date of

measurement .

Hours since last measurement .

Date of

measurement .

Hours since last measurement .

Date of

measurement .

Hours since last measurement .

Capacitance

DCL

Capacitance

DCL

Capacitance

DCL

µF

% change

µF

% change

µF

% change

Total failed

units 2/ .

Total unit hours since

last measurement .

Total failed

units 2/ .

Total unit hours since

last measurement .

Total failed

units 2/ .

Total unit hours since

last measurement .

1/ Designated test time shall be entered before life test is initiated.

2/ Only one failure shall be charged per unit regardless of number of parameters failed. NOTE: All measurements which exceed requirements shall be significantly marked as failures by underlining or circling the measurement.

FIGURE 1. Examples of FR test records.

4.6 Lot conformance FR inspection procedure (when specified). A lot conformance FR inspection (procedure IV, see 5.4) may be specified when reliability assurance beyond that guaranteed by procedure III (see 5.3) is required. The lot conformance FR inspection provides the manufacturer with a high assurance of acceptance of product at the specified FR level, and at the same time provides the consumer with reasonable protection against acceptance of products worse than the specified FR level.

4.7 Disposition of sample units. Sample units subjected to extended FR tests shall not be shipped. When the ER specification requires compliance with procedure IV (see 5.4) and allows the shipment of the lot conformance FR inspection samples, these units may be delivered on the contract or order provided:

a. The lot has passed the FR tests.

b. The part terminals were not soldered.

c. The part meets initial tolerance requirements.