MIL-PRF-19500P
APPENDIX C
C.8.2.1 Test optimization. The manufacturer may use statistical techniques and historical data to reduce, modify,
move, or eliminate tests. Manufacturer specific optimization requires the approval of the qualifying activity and
preparing activity. The manufacturer shall have a test optimization program in place that meets JEP121 or an
equivalent system, which justifies the proposed changes. Process monitoring and controls, statistical techniques
(i.e., process capability (Cpk), failure in time (FIT)), and accumulated data may be used to prove the validity of test
optimization. All optimizations shall be monitored for compliance to initial qualification baseline requirements.
C.8.2.2 Methods of test optimization. Test optimization includes the alternative methods listed below.
a.
Reduction of testing/sampling. This includes reduction in the number of samples or test frequency,
whether it is within a lot or periodic sampling.
b.
Modification of tests. This includes using alternative test procedures, or equipment.
c.
Moved tests. This pertains to performing tests in process instead of after all processing is complete.
d.
Elimination of tests. The tests are no longer performed.
e.
Any combination of the above.
C.8.3 Process validation: On-going reliability or conformance inspection. The process needs to be validated on a
regular basis to confirm continuing conformance to the originally qualified design parameters. The two methods of
validation are either conformance inspection (appendix E) or on-going reliability. Conformance inspection may only
be used as a validation for this appendix if a continuous improvement feedback loop is documented that ensures
conformance failures are analyzed for root cause and corrective actions are taken to modify both the FMEA and the
control plan, thereby eliminating the failure mechanism.
C.8.3.1 On-going reliability guidance criteria. With the approval of the qualifying activity and preparing activity, this
program, or an equivalent program, may be used as an alternative to the conformance inspection.
C.8.3.1.1 General elements of an on-going reliability program. An on-going reliability program is designed to create
a closed loop feedback system, which will generate continuous improvement. Existing production lines are constantly
sampled and tested. This proves the critical interfaces and manufacturing process are stable and repeatable, as well
as providing a mechanism for failures to be evaluated and the process improved. The on-going reliability program
shall include, as a minimum, the following:
a.
Program will formalize the routine reliability testing and tie failures to a specific manufacturing process.
b.
Program will integrate FMEA with reliability surveillance.
c.
Restructure surveillance program by "root technologies", rather than by individual part numbers.
d.
All on-going reliability testing will continue routinely.
e.
Samples will be tested as specified in a specified frequency in key environmental test, e.g., High
temperature reverse bias (HTRB), solder dip, and thermal shock.
f.
Failures will be reviewed and tracked to a specific manufacturing process.
g.
The on-going reliability program will record type of failure, manufacturing process, and root
cause/corrective action.
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