Application of Silver Nano Particle to Pressureless Bonding onto a Copper Surface - Consideration of Substitute Material for Lead Solder

Abstract:
In semi-conductor device bonding which supports today’s electronics, lead solder is still used. However, recent concerns about the environment have led to the consideration of limiting lead solder in RoHS, etc. In response to this trend, research and development of substitute material for lead solder have been actively carried out. One possible substitute for lead solder is the use of sinter silver as the bonding material. However, there are still issues remaining regarding its use as a lead solder substitute, sinter silver generally needs oxygen and a pressure process during bonding, and the bonding part must be a silver surface. This study shows the possibility of bonding to a copper surface using sinter silver, by analyzing the bonded interface of copper surface and silver. Our bonding material could bond to a copper surface in pressureless process under nitrogen, by applying silver nano particle which have a low-temperature sintering performance. Moreover, the bonding process of discrete parts was assumed, and dispenser printing was possible. This material is considered to be a positive candidate for substitute material for lead solder.