Solder Selections for Stacked Die and Low Temp Applications

Terence Collier, CV Inc.

A number of packaging limitations exist due to the availability of both solder alloys and application techniques. A good example is demonstrated in stacked die applications. The two principle alloys used in most flip chip applications are SnPb and SAC. A limitation occurs due to the fact that the first solder joint moves when subsequent reflows occur. Having multiple solders available as options provides an ability to run additional layers without compromising the position of the initial solder joints.

CVI has a proprietary technique for applying solder balls to die that expands the alloy options. For example SnPbBi, InPb, InSn, SnAu, AuSn, traditional SnPb and SAC have all been applied. The melt range is from 100C to 290C. This choice allows our customers great flexibility not only in stacked die assembly but expands to die to die assembly applications, MEMS applications and flex circuit assembly.

Terence is on his 20 year anniversay in the in both the defense and consumber electronics industry. He has a background in materials engineering and physics from the University of Illinois (Urbana). Terence has worked for a number of large public corporations as well as defense contractors. His roles have included product, process and reliability engineering in the areas of packaging, test and development. The job he enjoys most of all is teaching his 3 sons (ages 7, 5 and 3) how to play baseball and garden.