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.3.5.2.5.2 Rectangular surface mount lands (see figure F�6). Rectangular surface mount lands shall not contain

defects such as nicks, dents, and pin holes along the external edge of the land that exceed 20 percent of either the

length or width of the land and shall not encroach the pristine area, which is defined by the central 80 percent of the

land width by 80 percent of the land length as shown on figure F�6. Defects internal to the land shall not exceed 10

percent of the length or width of the land and shall remain outside of the pristine area of the surface mount land.

Electrical test probe 'witness' marks shall be acceptyable when within the pristine area.

A.3.5.2.5.3 Round surface mount lands and Ball Grid Array pads (see figure F�7). Round surface mount lands

and Ball Grid Array (BGA) pads shall not contain defects such as nick, dents and pin holes along the edge of the land

that radially extend towards the center of the land by more than 10 percent of the diameter of the land. In addition,

defects shall not extend more than 20 percent of the circumference of the land as shown on figure F�7. There shall

be no defects within the pristine area which is defined by the central 80 percent of the land diameter. Electrical test

probe 'witness' marks shall be acceptable when within the pristine area.

A.3.5.2.5.4 Wire bond pads. The maximum conductor finish roughness (surface roughness) for pads or areas

designated for wire bonding shall be no greater than 32 micro inches (0.8 micrometers). Unless otherwise specified,

the wire bond pad bonding area shall be defined as the pristine area as shown on figure F�6 for rectangular pads or

figure F�7 for round pads. There shall be no pits, nodules, scratches, electrical test probe 'witness' marks, or other

defects in the pristine area that exceed the surface roughness limits.

A.3.5.2.6 Holes for interlayer connections. The external annular ring of holes used for interlayer connections shall

be as specified. Unless otherwise specified, the external annular ring may have in isolated areas a 20 percent

reduction of the specified minimum external annular ring due to defects such as dents, pinholes, pits, or nicks.

A.3.5.2.7 Registration, external (method I).

A.3.5.2.7.1 Component hole lands Misregistration of component hole lands shall not reduce the minimum external

annular ring below the limits specified (see A.3.1.1).

A.3.5.2.7.2 Rectangular surface mount lands. The registration of rectangular surface mount lands shall be as

specified (see A.3.1.1).

A.3.5.2.7.3 Round surface mount lands. Round surface mount lands, such as Ball Grid Array (BGA) lands, using

copper�defined lands, solder mask-defined lands, or solder dam designs shall comply with IPC�7095.