Fatigue design method of aluminum bonding wires subjected to thermal cycles

Fatigue design method of aluminum bonding wires where fatigue failures originated at the highest part of the loop or the bond in thermal cycles, was studied. A mechanical fatigue testing system which can obtain displacement/loads induced to the specimen, was developed to simulate the displacement of the bonding wire by thermal deformation of the devices. By the mechanical fatigue tests applied to the specimens with several profiles, it was proved that the wire showed typical load/displacemen? hysteresis loops indicating low cycle fatigue. And it was found that the different profile specimens with the same fatigue life had almost the same stabilized bending stress range applied to the failure points. In regard to the fatigue behavior of the bond, a stress singularity analysis using three-dimensional finite element method was performed and the effects of the cross-sectional dimensions of the bonded wire on the fatigue strength were made clear by parametric analyses.