EFFECT OF GRINDING-INDUCED SCRATCH GEOMETRY ON FRACTURE STRENGTH OF PLASTIC-ENCAPSULATED SEMICONDUCTOR DEVICES

The fracture strength of LOC (lead-on-chip) packages was measured through three-point bending tests. Metallurgical examination shows that failure in an LOC package begins at a pre-existing flaw in the form of a scratch on the bottom surface of the plastic-encapsulated silicon chip. The flexural strength of LOC packages was estimated as a function of the geometry of the grinding-induced scratches on the back surface of the chips. The major conclusion is that the fracture strength of the plastic package, including the silicon chip, can be enhanced up to 80% by changing its scratch marks from 0°, running parallel to its lateral direction, to 90°, running parallel to its longitudinal direction.