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An introduction to acoustic-emission (AE)-based tests applied to quality control in the electronics industry is given. Bond integrity tests for tape automated bonding (TAB) devices using AE monitoring are described. These include a pull tester and a microfatigue tester for off-line evaluation of bond quality and metallurgical system reliability as well as a prototype of an automatic on-line production bond quality tester. The microfatigue tester for TAB leads can apply a small oscillatory (up to 80 Hz) force on top of a constant force bias of a few grams. A major result was that the most common metallurgical system (tin-plated copper leads bonded to gold bumps) results in the formation of brittle intermetailic compounds which crack relatively easily. The cracks propagate under cyclic stress and result in a very low fatigue life, compared to another TAB metallurgical system. The inner lead bond integrity tester and lead-forming system is designed to be used on-line. Precision tools apply a predetermined force to the leads, which nondestructively tests the bonds and forms the leads. The AE monitor can indicate any failures and the device can be rejected.
Components, Hybrids, and Manufacturing Technology, IEEE Transactions on (Volume:5 , Issue: 4 )
Date of Publication: Dec 1982