Palladium plating (electroplating) - Palladium per Mil-P-45209
Palladium, like gold, does not react with oxygen at room temperatures to form an oxide. Like gold, Palladium is well suited to plating applications where the prevention of oxide formation is required.
Palladium is one of 6 metals that belong to the Platinum Group of Metals (PGMs). The PGM's are all silver-white in color. The other 4 PGM's are platinum, rhodium, osmium, ruthenium, and iridium.
Palladium has a melting point of 2830F (1554C). We have used Pd in connector applications where post-plating ceramic insulator firing is involved.
The cost of palladium is usually lower, per ounce troy, than gold. See our current metal price charts for a cost comparison. In most general electronics applications, palladium is an excellent substitute for gold. Keep in mind though, that palladium is a white metal and very visually different from yellow gold.
Palladium has a Knoop hardness of up to 400. Compare this with cobalt hardened Type 2 gold which has a maximum Knoop hardness of 200. Palladium is an excellent choice in electrical contact applications where sliding contact wear or point contact wear are a concern. If extremely high wear conditions are present, we suggest that rhodium be considered.
Palladium has very good solderability characterstics. Standard soldering procedures used for gold are applicable to soldering palladium.
Anti-diffusion and multi-layer plating: Metallic copper diffuses very rapidly through metallic gold. However, copper will not diffuse through nickel or palladium. For this reason, a layer of nickel or palladium should always be considered between copper and gold. Copper which has diffused through gold will appear on the outer surface of the gold electrodeposit and will quickly begin to form a partial oxide layer on the surface of the electrodeposited part.Nickel is generally suggested as the anti-diffusion layer owing to its lower material cost. However, nickel is a magnetic metal whereas palladium is not. So in applications where non-magnetic performance is required, palladium would be the antiduffusion layer of choice. It could also be considered in a non-magnetic, non-oxidizing application as a replacement to gold.