Selective high-speed deposition of precious metals for technical applications - Some new developments

This paper gives an overview of a number of different new high-speed electrolytes for the electrodeposition of hard gold for connectors, of fine gold for bonding applications, as well as of silver for semiconductor devices. A hard gold electrolyte permits high plating speeds at relatively low, gold concentrations in the bath, which results in significant economic advantages. Due to its chemical composition, a fine gold electrolyte is characterised by an extremely long lifetime since dragged-in metallic contaminants can be selectively removed by means of ion exchangers. Even after a gold metal turnover of more than 100 MTOs, the bondability of the layers is still good. Silver layers deposited from a high-performance silver electrolyte are so bright that due to their high reflectivity the surfaces permit higher luminous efficiencies and better emissive power in optoelectronic components (e.g. light-emitting diodes). Furthermore, a ruthenium electrolyte is presented which seems to be suitable for applications under high-speed conditions.