A conceivably stable non-cyanide electroless gold plating for electronic packaging application

At present, the cyanide gold plating solution is widely used in industrial production due to the stability and excellent coating performance, but the cyanide is a highly toxic chemical, therefore non-cyanide gold plating has become a development tendency in industrial production. In this research, a very stable non-cyanide electroless gold plating bath composed by Sodium Gold Sulfide (Na₃Au(SO₃)₂), complexing agents and additives was developed for electronics assembly applications. Then the additives were investigated for their concentration and action mechanism, meanwhile the operating parameters were optimized by a series of single factor's and orthogonal experiments. Finally, we assessed the bath stability and comprehensively verified the reliability of coating. The result indicates the non-cyanide bath has sufficient stability and can provides the excellent Au coating to satisfy the industrial demand.