MIL-STD-1276 Leads For Electronic Component PartsThis standard establishes the method of identifying, specifying, and limiting to a minimum the combinations of basic materials, the thickness and composition of the plating used therewith, and the sizes of wire and flat wire ribbon leads on electronic and electrical parts when they are to be soldered or welded during assembly in equipment.

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MIL-STD-1276H

72   -       Silver plating, electrodeposited, matte, nonbrightened, in accordance with ASTM B700, grade A, class

N.  Thickness shall be 150 (3.81 μm) to 350 microinches (8.89 μm).

5.2.1  Underplating.  The underplating (see 1.2.1.5) shall conform to the following requirements: A        -       Nickel electrolytic.

1   -   60 (1.52 μm) to 150 microinches (3.81 μm) thick.

2   -   100 (2.54 μm) to 300 microinches (7.62 μm) thick.

3   -    20 (0.50 μm) to 60 microinches (1.52 μm) thick.

B     -       Nickel, electroless (not to be used on flexible or semirigid leads).

1   -   100 (2.54 μm) to 200 microinches (5.08 μm) thick.

2   -    50 (1.27 μm) to 120 microinches (3.04 μm) thick. C    -       Copper, electrodeposited.

1   -   60 (1.52 μm) to 150 microinches (3.81 μm) thick.

2   -   150 (3.81 μm) to 300 microinches (7.62 μm) thick.

3   -    20 (0.50 μm) to 60 microinches (1.52 μm) thick. P     -       Palladium-nickel alloy

1   -     50 (1.27 μm) to 100 microinches (2.54 μm) thick. N    -       No underplating.

5.2.1.1  Gold plating.  A copper plus electrodeposited nickel or electrodeposited nickel underplating is required on all leads with gold plating as the final finish in accordance with SAE-AMS2418.

5.2.1.2  Compositions F, G, and K.  All leads with composition F, G, or K (see 5.1) shall have an underplating prior to final finish.

5.2.1.3  Hot solder dip.  When specified for use under hot solder dip lead finish (see 5.2), the electroless nickel underplating shall be in accordance with SAE-AMS2404.  The thickness shall be as designated in 5.2.1.B.

5.2.1.4  Compositions A, B, J, and X.  All leads with compositions A, B, J. or X (see 5.1) shall have a copper or nickel underplate of 100 microinches (2.54 μm) minimum.

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