MIL-PRF-28750F
4.4.3 Failures. No failures shall be allowed for group Q1, and only one failure shall be allowed for group Q2, group
Q3, and group Q4 combined. Failures in excess of those allowed shall be cause for refusal to grant qualification
approval.
4.5 Retention of qualification. To retain qualification, every 24 months, the contractor shall provide verification of
the following requirements:
MIL-STD-790 program.
a.
b.
Design of the SSR has not bee modified.
c.
Screening tests, conformance tests, and periodic tests have been performed as specified herein.
d.
The contractor retains the capability to manufacture and test SSR's to this specification.
e.
Continued qualification to screening level W shall be based on continued maintenance of qualification for
screening level Y.
In the event that no production occurred during this period, the contractor shall still verify to the qualifying activity the
capability to manufacture and test the QPL SSR still exists and the contractor wants to remain on the QPL.
4.6 Conformance inspection.
4.6.1 Inspection of product for delivery. Inspection shall consist of group A inspection.
4.6.1.1 Production and inspection lot.
4.6.1.1.1 Production lot. A production lot shall consist of all SSR's covered by a single specification sheet and
single PIN. All SSR's in the lot shall have been started, processed, assembled, and tested as a group. Lot identity
shall be maintained throughout the manufacturing cycle.
4.6.1.1.2 Inspection lot. An inspection lot shall consist of all SSR's covered by a single specification sheet,
produced and sealed under essentially the same conditions, and offered for inspection at one time within a period not
to exceed 1 month.
4.6.1.2 Group A inspection.
Screening level Y: Group A inspection shall consist of the inspections specified in table II, in the order
a.
shown.
b.
Screening level W: The manufacturer shall establish and maintain an inspection system to verify that these
SSR's meet the electrical, visual, mechanical, and solderability requirements. In-line or process control
may be part of such a system. The inspection system shall also include criteria for lot rejection and
corrective actions. The inspection system shall be verified under the overall QPL system (see 3.3). NOTE:
Since screening level W is the same design as screening level Y without the mandatory conformance
inspection, screening level W product shall meet the environmental qualification type requirements (such as
moisture resistance, shock, and vibration).
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