Accelerated life time measurement with in-situ force and displacement monitoring during thermal cycling on solder joints

This paper is focused on the thermally-induced thermo-mechanical load in interconnections of electronic products, which are necessary to connect an electronic component on substrate material (such as Printed Circuit Board). In order to improve of the material selection, the Fraunhofer IKTS has developed a measurement setup enabling a cost-efficient material characterization in terms of mechanical and fatigue values. The developed setup is able to measure mechanical quantities on a realistic specimen which is stressed under thermo-mechanical load of predefined magnitude. The setup consists of a construction (load frame) with integrated force and contactless displacement sensors to monitor the changes in strength of a specimen in-situ. The first measurement results present a comparison of the influence of two temperature cycling profiles relevant for automotive electronics industry. The realistic specimen comprising four BGA-like solder joints is subjected to temperature cycles until a substantial structure-mechanical failure is observed. Further, the paper presents the calibration steps necessary to understand the unique force-deformation behaviour of the system as function of temperature.