MIL-PRF-50884 Printed Wiring Board, Flexible Or Rigid-Flex, General Specification ForThis specification establishes the performance and qualification requirements for flexible and rigid-flex printed wiring boards with or without plated through holes \(see 6.1\). Verification is accomplished through the use of one of two methods of product assurance \(appendix A or appendix B\). Detail requirements, specific characteristics, and other provisions which are sensitive to the particular intended use are specified in the applicable master drawing.

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MIL�PRF�50884F

APPENDIX A

A.3.5.1.3.2 Foreign inclusions between printed board surface and stiffener (types 1, 2, and 3 only). Translucent

foreign inclusions located between the printed board surface and stiffener shall be acceptable provided they comply

with the following:

Any bulge caused by the inclusion is no larger than .004 inch (0.1 mm).

Any inclusions shall not be larger than 5 percent of the bonding area of the stiffener.

There shall be no contact of the inclusion with a component hole or the printed board periphery. Any thread-

like inclusion shall not protrude more than .04 inch (1.0 mm) from the printed board periphery

There shall be no inclusions that reduce the spacing between adjacent access openings below the minimum

spacing specified in A.3.5.2.4.

A.3.5.1.3.3 Subsurface spots. Subsurface spots shall be acceptable provided they meet any of the following:

The spots are translucent.

The spots are known to be weave texture other than delamination or disbonding.

The spots are isolated white spots that do not propagate as a result of any soldering operation (gelation

particles are acceptable regardless of location).

A.3.5.1.3.4 Adhesive voids (for metal clad flexible base materials only). Adhesive voids that are no greater than

.020 inch (0.51 mm) or 25 percent of spacing shall be acceptable.

A.3.5.1.3.5 Measling and crazing. Measling and crazing shall not exceed the class 3 acceptable requirements

specified in IPC�A�600, for bare printed wiring boards.

A.3.5.1.3.6 Exposed or disrupted reinforcement fibers. Exposed or disrupted reinforcement fibers shall be

acceptable provided they do not bridge conductors and do not reduce the conductor spacing below the specified

minimum.

A.3.5.2 Conductor pattern.

A.3.5.2.1 Bonding of conductor to base material and lifted lands. There shall be no peeling or lifting of any

conductor pattern or land from the base material. The completed printed board shall not exhibit any lifted land.

(NOTE: See A.3.6.2.5 for allowances for the acceptable lifting of lands, i.e. lifted lands, following rework simulation,

resistance to soldering heat, and thermal shock testing.)

A.3.5.2.2 Conductor finish. The conductor finish shall be as specified. Unless otherwise specified, the following

requirements shall apply.