Feasibility Studies of Cyanide-Free Gold Plating Solutions For Electronic Connector Plating Applications

摘要

Increasingly stringent regulatory restrictions on the chemical industry continue on a global basis. Governmental regulations may in some cases force manufacturers to abandon well-established, proven solutions and force the adoption of inferior, non-feasible and/or higher cost solutions in order to be in compliance. A recent example is a policy statement issued by China's "National Development and Reform Commission" (NDRC) in March 2013, of which a summary translation states: "Any plating process containing toxic and hazardous cyanide (i.e., gold plating of potassium gold(III) cyanide (KAu(CN)4) and potassium aurocyanide (KAu(CN)2)) will be banned by the end of 2014". This regulation was met with widespread industry resistance and in September 2013 the government decided to postpone the legislation. However, most users of potassium gold cyanide (PGC) consider this to be a warning and it is expected that the legislation will ultimately be enacted. The electronic plating industry is the largest user of PGC in China and globally. While it is technically feasible to replace PGC in some applications - particularly those involving pure gold in rack or barrel plating applications - so far no process has been developed that is free of PGC in high speed 'hard' alloyed gold applications which are most commonly used in the electronic connector plating industry. This paper will describe the challenges involved in formulating a plating process chemistry which is free of all cyanide-compounds (including PGC) for electronic connector plating applications. Studies of several different electrolytes will be presented, and a novel solution will be introduced which satisfies the basic properties required as a contact finish for the connector plating industry.