Missing ball improvement for different lead free solders

Government regulations for handling electronic waste materials are becoming more stringent. The European Union (EU) and China implemented regulations on the restriction of use of hazardous substances (RoHS) for electrical and electronic equipment on 1 July 2006 and 1 March 2007 respectively. One of the many intentions of these regulations is to ban the use of lead (Pb), which is commonly used for BGA solder ball. BGA solder ball composition need be changed from eutectic solder (Sn63Pb37) to SnAgCu or SnAg lead free solders, because of above environmental and regulation reasons. Since the introduction of Pb-Free initiatives, both academic and industry have extensively investigated solder ball composition and proposed to use SAC305/405 solder alloys because of its higher strength and reasonable melting point. However, on volume production, the industry realized these alloys are more fragile, and susceptible to high ppm level of IMC fracture under high-strain rate, e.g. handling, shipping, socketing etc.