A drawback of converting to a low stress molding compound

This paper presents a failure mechanism resulting in interfacial cracks and broken wedge bonds that was occasionally encountered on some plastic DIPs with large leadframe paddle upon conversion to a lower stress molding compound. The root cause of the problem was a pull force during leads forming in excess of the strength of the center lead/wedge bond/molding compound structure. The paper-shows how acoustic microscopy and finite element analysis enabled the elimination of the problem via optimization of the packaging processes and redesign of some leadframes