MIL-PRF-28750F
APPENDIX B
B.3.3.4.4.2.2 Conductor resistivity. Measure conductor resistivity in accordance with the applicable substrate detail
specification. Conductor resistivity shall meet the requirements specified in the applicable substrate detail
specification.
B.3.3.4.4.2.3 Film adhesion. The manufacturer is responsible for establishing the appropriate test method for
compliance with film adhesion specifications herein. The substrate tape shall show no evidence of peeling or flaking
of metallization.
B.3.3.4.4.2.4 Solderability. For solderable substrates only, perform solderability testing, if specified in the
applicable substrate detail specification, in accordance with the applicable substrate detail specification.
B.3.3.4.4.3 Subgroup 3. A minimum of two samples that have been subjected to, and passed, subgroup 1 testing
shall be submitted to subgroup 3 testing.
B.3.3.4.4.3.1 Temperature coefficient of resistance (TCR): When specified in the applicable detail specification,
perform TCR testing for resistors in accordance with MIL-STD-202, method 304. TCR shall meet the requirements
specified in the applicable substrate detail specification.
a.
Thick film type: Test as a minimum, two resistors from each resistor paste sheet resistance value. One
from the smallest and one from the largest area resistors at -55C, and +125C using a reference reading at
+25C, or temperatures as specified in the substrate detail specification.
Thin film type: Test as a minimum, the highest value resistor at +125C using a reference reading at +25C
b.
or temperatures as specified in the substrate detail specification.
c.
If specified in the applicable detail specification, TCR tracking testing shall be performed. TCR tracking
shall meet the requirements specified in the applicable substrate detail specification.
B.3.3.4.4.3.2 Wire bond strength testing. For wire bondable substrates, perform wire bond strength testing in
accordance with MIL-STD-883, method 2011. The sample shall include at least 2 substrates and 10 bond wires
minimum.
a.
At least 10 wires, consisting of substrate to substrate bonds, shall be destructively pull tested. An equal
number of bonds shall be tested on each sample substrate.
b.
The substrate metallization shall be acceptable if no failure occurs. If only one wire bond fails, a second
sample of a minimum of 20 wires shall be prepared using the same wire type/size and the same type
equipment as the failed bond. If the second sample contains one or more failures, or if more than one
failure occurs in the first sample, then the substrate inspection lot shall be rejected.
b.
The substrate inspection lot may be resubmitted to evaluation if the failure(s) was not due to defective
substrate metallization.
B.3.3.4.4.3.3 Die shear strength testing. Perform shear strength testing in accordance with MIL-STD-883, method
2019. At least two die per substrate shall be attached and tested for each die attachment method, as specified in the
applicable substrate detail specification. If a failure occurs at less than the specified force and is not due to defective
substrate materials, the lot shall be resubmitted to die shear evaluation and the failure mode documented.
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