MIL-STD-1250A
TABLE I. Selection of metallic coatings for minimum corrosion.
Purpose |
Recommended |
Not Recommended |
Contact with aluminum Prepaint coating Tarnish prevention Marine exposure Solderability Storage Wear |
Cadmium or tin Cadmium or tin Rhodium over silver Gold over silver, copper or nickel Nickel between copper and silver (See 4.2.r) Heavy gold 0.00030 inch minimum Tin, gold or tin-lead Gold, rhodium, or reflowed heavy tin Chromium, nickel, rhodium or hard gold |
Chromium, copper, silver, gold, nickel Chromium, copper, nickel, gold, silver Nickel, chromium, rhodium Cadmium, silver, copper Cadmium, tin |
5.3.6.4 Gold plating. Gold plating shall be in accordance with MIL-G-45204. Special care shall be taken to prevent or retard diffusion of substrate metals, especially copper into the gold electro-deposits. A suitable barrier to prevent diffusion is a thin nickel or palladium coating under the gold. Thickness of gold shall be sufficient to minimize porosity and provide corrosion protection. The recommended minimum thickness of gold plating is 0.000050
inches over 0.000100 inches minimum of the barrier coating. Attention is directed to problems of brittle gold solder compound formation (see 5.7.5) and of Purple Plague when bonding gold to aluminum (see 5.7.7).
5.3.6.5 Nickel coating. Nickel coatings shall be electrodeposited in accordance with QQ-N-290, or electrolessly deposited in accordance with MIL-C-26074 or AMS 2404. Corrosion resistance shall meet the requirement of AMS 2404. Where desired for electrical bonding, nickel-cadmium coating shall be in accordance with AMS 2416. Nickel shall be
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