Optimization of Forming Process Involving Connecting Reliability with Solder-Free Electronic Parts.

In this study we discussed on the connecting reliability of the solder-free electronic parts with an attention to the optimization of forming process, which is decision of cross section shape and manufacturing method. The optimization was carried out with the popular FEM analysis code MSC-MARC. Residual stress on microscopic area of electronic parts was analyzed with the special X-ray stress measurement system which could search stress on microscopic area(150μm×150μm). The results were as follows. (1)The cross section shape having high holding force was determined by the theory of curved beam model. This theory showed that the important design factors were the redius and the thickness of cross section shape. (2)There was a remarkable difference of cyclic bending endurance between two parts manufactured by different method, although the two electronic parts were formed in the same shape. The residual stress induced by the plastic working process was mainly the dominant factor of the bending strength. (3)The high connecting reliability of solderfree electronic parts was obtained by the optimization of forming process that was the design concepts of the cross section shape and the manufacturing process relating to the induced residual stress.