STATS picks pure-tin solder as best lead-free packaging solution

SINGAPORE -- ST Assembly Test Services Ltd. (STATS) today announced it plans to offer pure-tin (Sn) solder as a lead-free solution in chip packaging and interconnect assemblies for customers needing to comply with environmental regulations.

Requirements for lead-free assemblies and chip products are spreading around the world. Initiatives are being driven by the Japanese Electronic Industry Association (JEIDA) and by European legislation, known as Waste in Electrical and Electronic Equipment (WEEE). Consequently, electronics manufacturers and chip suppliers are now being pressured to find reliable alternatives for lead-based solder.

"The goal of STATS' green initiative was to achieve environmentally friendly packaging while maintaining the performance, reliability, and quality standards our customers require," said Tan Bock Seng, chairman and CEO of the Singapore contract assembly and test company.

STATS said it began researching lead-free alternatives in early 1999. The research has also focused on alternative finishes for components as well as reliability of molding compounds that do not contain bromine (Br) and antimony (Sb), which are flame retardants that can impact the environment.

The company noted that pure tin finishes have been widely used in some semiconductor devices. Its research has evaluated Sn solder against other lead-free finishes for a variety of package sizes, lead pitches, and materials. Recent breakthroughs by electroplating chemical companies have made pure-tin a strong candidate for replacing tin-lead (SnPb) finishes, according to STATS.

A lead-free solder ball alternative--consisting of tin-silver (SnAg) and tin-silver-copper (SnAgCu)--is also under evaluation by STATS for array product assemblies. Lead-free solder ball qualification and the collection of board-reliability data will be completed by the end of this year, said the Singapore company. This lead-free solution is expected to be available by the middle of 2001.

STATS also reported it is evaluating alternative molding compounds to enhance the "environmental friendliness" of its package offering while improving moisture sensitivity levels. Qualification of these new molding compounds is also slated to be completed by the end of 2000.