Platinum-Group Metals Plating,Platinum-Group Metals Plating,Platinum-Group Metals Plating,Platinum-Group Metals Plating
THE SIX PLATINUM-GROUP METALS (PGMs), listed in order of their atomic numbers, are ruthenium, rhodium,
palladium, osmium, iridium, and platinum. The PGMs are among the scarcest of metallic elements, and thus their cost is
high. Their most exceptional trait in the metallic form is their excellent corrosion resistance. The electroplating of PGMs
from aqueous electrolytes for engineering applications is limited principally to palladium and, to a much lesser extent, to
platinum, rhodium, and thin layers of ruthenium. There are practically no electrolytes on the market for the deposition of
osmium or iridium. While solution formulations have been published for these last two metals, they have not proven
themselves in practical use for any significant applications, and thus will be discussed only briefly in this article.

Ruthenium Plating
Ruthenium in the solid form is hard and brittle; furthermore, it oxidizes rather easily. These factors limit its use, even as
its low price relative to the other PGMs provides impetus for its application. Despite extensive research work on
electroplating of ruthenium, it has obtained a small market share in only two areas: for decorative applications such as
eyeglass frames and for layers on electrical contacts used in sealed atmospheres.
All ruthenium plating electrolytes are based on solutions of simple ruthenium salts or ruthenium nitrosyl derivatives.
Typical examples are ruthenium sulfate, ruthenium phosphate, ruthenium sulfamate, or ruthenium chloride (Ref 4). These
electrolytes are all essentially based on those described in Ref 5 and 6. They work in a wide range of current densities
from 1 to 10 A/dm2 (9 to 93 A/ft2) at temperatures between 50 and 90 °C (120 and 195 °F), and at current efficiencies of
50 to 90%.

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