MILPRF50884F
APPENDIX A
A.3.7.5 Electrical requirements.
A.3.7.5.1 Circuit continuity and shorts. When specified (see A.3.1.1) that it is acceptable, verification of circuit
continuity and shorts by indirect testing by signature comparison may be used for production screening.
A.3.7.5.1.1 Circuit continuity. When tested as specified in A.4.8.5.1, the resistance between the endpoints of
conductor patterns within a network of conductors shall be as specified (see A.3.1.1). For qualification inspection
there shall be no circuits whose resistance exceeds 20 ohms. Unless otherwise specified (see A.3.1.1), for
production printed wiring boards, there shall be no circuit whose resistance exceeds 10 ohms. For referee purposes,
0.5 ohm maximum for each inch of circuit length shall apply. Conductor patterns that consist of long runs of narrow
conductors or short runs of very wide conductors may increase or decrease the resistance. The acceptability of
these type of circuits, of controlled impedance nets, or of embedded resistive patterns shall be specified.
A.3.7.5.1.2 Circuit shorts (isolation resistance). When tested as specified in A.4.8.5.1, the insulation resistance
between mutually isolated conductors shall be as specified (see A.3.1.1) Unless otherwise specified (see A.3.1.1),
for production printed wiring boards, the insulation resistance shall be greater than 10 megohms.
A.3.7.5.2 Circuit or plated-through hole short to metal core substrate. When printed wiring board designs with
metal cores are tested in accordance with A.4.8.5.2, the dielectric material used to insulate the heat-sinking plane
from circuitry and plated through holes shall provide an insulation resistance greater than 2 megohms. Electrical
access to the metal core substrate shall be provided in the design when this test is to be performed.
A.3.7.5.3 Dielectric withstanding voltage (DWV). When inspected as specified in A.4.8.5.3, there shall be no
flashover, sparkover, or breakdown between isolated conductors.
A.3.7.5.4 Impedance testing (when specified). When impedance resistance values are specified, all printed wiring
boards shall be electrically testing tested as specified in A.4.8.5.4.
A.3.7.6 Environmental requirements.
A.3.7.6.1 Moisture and insulation resistance (MIR). When tested as specified in A.4.8.6.1, the printed wiring board
test specimen shall have a minimum of 500 megohms of resistance between conductors. After the test, the printed
wiring board test specimen shall be inspected in accordance with A.4.8.1 and the specimen shall not exhibit
blistering, measling, or delamination in excess of that allowed in A.3.5.1.3.
A.3.7.6.2 Resistance to soldering heat.
A.3.7.6.2.1 Solder float thermal stress (single side, single cycle, component holes).
A.3.7.6.2.1.1 Types 1 and 5. After undergoing the test specified in A.4.8.6.2, the printed wiring board test
specimen shall be inspected in accordance with A.4.8.1 and shall not exhibit any cracking or separation of plating and
conductors, blistering or delamination of base materials shall not exceed the limits allowed in A.3.5.1.3, and lands
shall not lift in excess of that allowed in A.3.5.2.1.
A.3.7.6.2.1.2 Types 2, 3, and 4. After undergoing the test specified in A.4.8.6.2, the printed wiring board test
specimen shall be examined in accordance with A.4.8.1 and shall exhibit no blistering or delamination in excess of
that allowed in A.3.5.1.3. After meeting the visual and dimensional requirements of A.3.5, the printed wiring board
test specimen shall be microsectioned and inspected in accordance with A.4.8.2 and the requirements of A.3.6 shall
be met.
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