EVALUATION OF LOW-TEMPERATURE SNAP-CURE DIE ATTACH MATERIALS

Polymeric adhesive materials have been extensively used for die attach ment in plastic IC package assembly for over two decades. They offer m any advantages over gold-eutectic solder, soft solders, or silver-glas s attach materials, due to lower temperature processing, lower stress on the chip, and lower cost. Recently, improved polymeric adhesive mat erials are entering the market. Snap-cure adhesives can reduce process ing time and steps, which translates into cycle time reduction and cos t savings. In addition, a lower temperature-cure material also provide s compatibility with tin-lead solder pre-plated lead frames for assemb ly flow simplification, as well as for temperature-sensitive devices. However, since these materials are relatively new, their effect on rel iability on the encapsulated IC device is not well known, especially w ith respect to the volatile species evolved during cure and post-cure processing. The snap-cure adhesive chemistry differs from that of stan dard polymeric die attach materials. How that affects stress, thermal, and reliability behavior of the package requires study. This paper ex amines the differences in the material design of the snap-cure versus oven cure adhesives, and how that relates to assembly processability a nd package reliability. From the results, snap-cure die attach materia ls show comparable or superior performance to conventional polymeric d ie attach materials in these areas, which should aid their acceptance into the simplification of the plastic IC assembly flow.