Abstract
The plated gold being used by the electronics industry can be broadly classified into two categories: soft gold and hard gold. Soft gold is used for circuit metallization and for bonding semiconductor chips, while hard gold is indispensable as the contact material on electrical connectors, electromechanical relays, and printed circuit boards. The traditional baths from which to plate soft gold as well as hard gold contain the cyanide complex, [Au(CN)2]-, as the source of gold, which liberates free cyanide ions during the plating. The free cyanide is not only highly toxic but also attacks photoresists used to delineate circuit patterns and bonding pads. For these reasons, noncyanide baths are in use to plate soft gold, whereas hard gold can be plated only from cyanide baths at present. In this presentation, the current status of both electrolytic and electroless non-cyanide processes for plating soft gold will be reviewed.
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Dr. Masaru Kato is employed by Kanto Chemical Co., Inc., Japan, a major producer of reagent chemicals and high purity chemicals for the electronics industry. He received his Bachelor of Engineering degree in applied chemistry from Tohoku University, Sendai, and a Doctor of Engineering degree from Waseda University, Tokyo, Japan. He is a Group manager at the company's central research Laboratory. He has been actively involved in the development of gold plating, especially electroless gold plating for the past fifteen years. His research interests include the electrochemistry of deposition and etching of metals. Dr. Okinaka has been involved in the R & D of the electrolytic and electroless plating of metals, primarily gold and copper, for electronics applications for more than 35 years. After retirement from AT&T Bell Laboratories, USA in 1990, he was a Visiting Professor at Waseda University, Tokyo, Japan until 1996, where he continues to participate actively in research as a Visiting Research Scientist. He also serves as a Technical Consultant for Kanto Chemical Co.
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Kato, M., Okinaka, Y. Some recent developments in non-cyanide gold plating for electronics applications. Gold Bull 37, 37–44 (2004). https://doi.org/10.1007/BF03215515
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DOI: https://doi.org/10.1007/BF03215515