American Machinist

Safer fine-gold electrolytes. (Degussa Electroplating)

Safer fine-gold electrolytes To refine grain size and improve appearance of fine-gold (99.9% minimum) electrodeposits used for bonding purposes in the semiconductor industry, the electrolytes, or gold baths, include additives such as thallium, lead, arsenic and hydrazine.

Besides being particularly toxic, thallium, arsenic and lead pose problems in bath stability and in ensuring bond quality. Hydrazine, which is on the list of carcinogenic chemicals, is widely used in conjunction with arsenic to increase current yield of low-density-current baths.

Free of all these additives is a new family of gold electrolytes developed by Degussa Electroplating, West Germany. Although further tests are required to fully assess their performance, preliminary results are encouraging. …

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