Nanoanalysis of Interreactions
Growth morphology of Cu/SnPb solder reaction
Soldering is one of the oldest joining techniques for metals. Down-scaling of packaging in microelectronics
requires a more detailed understanding of the reaction between the solid metal and the liquid solder. The
mechanical stability of the joints depends on the formation of an intermetallic compound inside the reaction
zone. In our
experiments we studied the reaction of Cu with liquid Sn as well as with liquid SnPb. In both cases no planar
reaction product is formed, but a scallop like structure. This is distinguished by liquid channels allowing the fast
transport across the intermetallic, so that rather high reaction rates result that hinder the down scaling of solder
joints in the range below one micrometer. However for modern technology the reduction of the size of solder
joints is desired. By the right choice of materials and suitable thermal treatment the reaction rate should be
influenced to reach this goal.
