MIL-PRF-38535K
APPENDIX D
STATISTICAL SAMPLING, TEST, AND INSPECTION PROCEDURES
D.1 SCOPE
D.1.1 Scope. This appendix contains statistical sampling, life test, and qualification procedures used with
microcircuits. This appendix is a mandatory part of the specification. The information contained herein is intended
for compliance.
D.2 APPLICABLE DOCUMENTS
(This section is not applicable to this appendix.)
D.3 REQUIREMENTS
D.3.1 Definitions. The following definitions shall apply for all statistical sampling procedures:
a. Sample size series: The sample size series is defined as the following decreasing series of values: 50, 30,
20, 15, 10, 7, 5, 3, 2, 1.5, 1, 0.7, 0.5, 0.3, 0.2, 0.15, and 0.1.
b. Tightened inspection: Tightened inspection is defined as inspection performed using the next sample size
value in the sample size series lower than that specified.
c. Acceptance number (c): The acceptance number is defined as an integral number associated with the
selected sample size which determines the maximum number of defectives permitted for that sample size.
d. Rejection number (r): Rejection number is defined as one plus the acceptance number.
D.3.2 Symbols. The following symbols shall apply for all statistical sampling procedures:
a. Acceptance number (c).
b. Rejection number (r).
D.4 STATISTICAL SAMPLING PROCEDURES AND TABLE
D.4.1 General. Statistical sampling shall be conducted using the sample size method. The sample size method
as specified herein is a sampling plan which provides a high degree of assurance that a lot having a percent defective
greater than or equal to the specified sample size value shall not be accepted. The procedures specified herein are
suitable for all quality conformance requirements.
D.4.1.1 Selection of samples. Samples shall be randomly selected from the inspection lot or inspection sublots.
For continuous production, the manufacturer, at their option, may select the sample in a regular periodic manner
during manufacture provided the lot meets the formation of lots requirement.
D.4.1.2 Failures. Failure of a unit for one or more tests of a subgroup shall be charged as a single failure.
D.4.2 Single-lot sampling method. Quality conformance inspection information (sample sizes and number of
observed defectives) shall be accumulated from a single inspection lot to demonstrate conformance to the individual
subgroup criteria.
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ACTEL [ Actel Corporation ]
