Specifications:

Mil-G-45204, MIL-DTL-45204, ASTM B488, AMS 2422, AMS 2425
Specification: MIL-G-45204 Gold Plating, Electrodeposited

• Type I 99.7 % gold minimum; hardness grades A, B, or C. Gold plating used for general-purpose, high-reliability electrical contacts, solderability, and wire wrap connections
• Type II 99.0 % gold minimum; hardness grade B, C, or D. A general-purpose, wear-resistant gold. It will not withstand high-temperature applications because the hardening agents in the gold plating will oxidize.
• Type III 99.9 % gold minimum; hardness grade A only. Gold plating for semiconductor components, nuclear engineering, thermo compression bonding, and high-temperature application.

Purity & Coating Thickness :

Co-deposited impurities can make soldering more difficult, and for this reason high purity gold plating is preferred. Soldering requirements are best achieved when gold electroplating coatings range between 0.00005 and 0.0001 inch (50 and 100 micro inches) thickness.

Underplate Recommendations :

when gold is applied to a copper rich surface such as brass, bronze, or beryllium copper, metal ions from these base metals will diffuse into the gold layer and degrade its hardness and non-oxidizing properties. An anti-diffusion underplate such as nickel (electroless or sulfamate) should be applied to prevent this.

We recommend electroless nickel under gold where part flexure or deformation is not expected and a bright finish is desirable. Where part flexure or deformation is expected, we recommend sulfamate nickel as the underplate because of its higher ductility.