MIL-PRF-27G
4.6.1.5.1.1 Failed samples(s). If a sample fails to pass group B inspection, the cognizant inspection activity and
the qualifying activity shall be notified immediately. The manufacturer shall take corrective action on the materials or
processes, or both, as warranted, and on all units of product which can be corrected and which were manufactured
under essentially the same conditions, with essentially the same materials, process, etc., and which are considered
subject to the same failure. Delivery of product level M transformers/inductors prior to completion of group B testing
shall be discontinued until corrective action, acceptable to the government, has been taken. As an alternative, if the
inspection lots have not been shipped, the inspection lots shall be subjected to 100 percent inspection and defectives
removed.
4.6.1.5.2 Product level T transformers/inductors. A sample of parts shall be randomly selected from the inspection
lot that have passed group A inspection in accordance with table VIII. If one or more defects are found, the sample
has failed.
4.6.1.5.2.1 Failed samples(s). If a sample fails to pass group B inspection, the cognizant inspection activity and the
qualifying activity shall be notified immediately. The manufacturer shall take corrective action on the materials or
processes, or both, as warranted, and on all units of product which can be corrected and which were manufactured
under essentially the same conditions, with essentially the same materials, process, etc., and which are considered
subject to the same failure. As an alternative, if the inspection lots have not been shipped, the inspection lots shall be
subjected to 100 percent inspection and defectives removed.
4.6.1.5.3 Disposition of sample units. Sample units, which have passed group B inspection, may be delivered on
contracts or purchase order if the lot is accepted.
4.7 Methods of inspection.
4.7.1 Visual and mechanical examination.
4.7.1.1 External. Transformers and inductors shall be examined to verify that the materials, external design and
construction, physical dimensions, weight, marking, and workmanship are in accordance with the applicable
requirements (see 3.1, 3.3 to 3.3.3.3 inclusive, 3.4.1, 3.4.3 to 3.4.3.3 inclusive, 3.4.5, 3.4.6, 3.4.8, 3.27 and 3.30).
4.7.1.1.1 Post test. Transformers and inductors shall be examined to verify that the protective coating, filling
material, marking, and case construction are in accordance with the applicable requirements (see 3.24).
4.7.1.2 Internal. Transformers and inductors shall be disassemble and/or dissected and examined to verify that
the materials, internal lead wires, internal mounting, impregnating, potting, and workmanship are in accordance with
4.7.2 Solderability (see 3.5). Transformers and inductors shall be tested in accordance with 4.7.2.1 or 4.7.2.2, as
applicable.
4.7.2.1 Solder bath method (for Surface Mount Devices and printed circuit terminals). Transformers and inductors
shall be tested in accordance with method 208 of MIL-STD-202. The following details shall apply:
a.
Special preparation of specimen - Sample units shall not have been soldered during any of the previous
tests.
b.
Number of terminations of each part to be tested - A minimum of two of each type of terminal.
4.7.2.2 Soldering iron method (for all other terminal types). The test shall be performed on all solder terminals
attached to the transformer or inductor. The solder shall conform to J-STD-004, composition Sn60Pb40A or
Sn63Pb37A. The flux shall conform to J-STD-006, form W and flux symbol A, flux percentage symbol 6 or 7. The iron
and solder shall be applied to the termination. Tinning for free flowing of the solder with proper wetting shall be evident.
The transformer or inductor under test shall remain under standard atmospheric conditions for recovery for fifteen
minutes, before final measurements are made.
a.
Special preparation of specimen - The surface shall be smooth and properly tinned and the solder
terminations shall not have been soldered during any previous test.
b.
Number of terminations - In accordance with 4.7.2.1.
c.
Examinations of terminations - In accordance with method 208 of MIL-STD-202.
d.
Point of application of soldering iron - 1/4 inch from the nearest insulating material or to one-half the
exposed length of the terminal, whichever point is closer to the insulating material.
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