Die attach by temperature gradient lead free soft solder metal sheet or film

摘要

A die attach process employs a temperature gradient lead free soft solder metal sheet or thin film as the die attach material. The sheet or thin film is formed to a uniform thickness and has a heat vaporizable polymer adhesive layer on one surface, by which the thin film is laminated onto the back metal of the silicon wafer. The thin film is lead-free and composed of acceptably non-toxic materials. The thin film remains semi-molten (that is, not flowable) in reflow temperatures in the range about 260° C. to 280° C. The polymer adhesive layer is effectively vaporized at the high reflow temperatures during the die mount.