Thermo-mechanical reliability of microcomponents and microsystems in automotive applications

The talk presents the results of a series of experiments and combined numerical calculations for various kinds of automotive sensors and different microcomponents and microsystems for "high tech" applications in automotives. With the growing miniaturization, the "local" properties of interconnected materials exert a greater influence on the reliability of microcomponents and microsystems, than in any macroscopic component. The research team of the authors has applied such experimental techniques as acoustic microscopy, laser scanning microscopy, thermography, various kinds of laser field measuring techniques, x-ray stress analysis and microDAC method, combined with FEA field simulation and reliability concepts. Special attention is given to the analysis of thermal fatigue and creep behaviour of solder regions (e.g. solder bumps and microsolder interconnects) in the near chip regions of microsystem packages and housings. Advanced packaging strategies in automotive applications (e.g. micromechatronic packaging approach, area array packaging, CSP etc.) are in the focus of the research. The authors deal with microMoire and microDAC techniques using a laser and electron beams for the detection of local microdeformation fields as well. Different automotive sensors, HF devices and other microcomponents and microsystems have been investigated and evaluated with respect to reliability and lifetime estimation. Crack avoidance strategies have been developed and successfully aplied to various applications. Besides the classic concepts of FEA also stochastic FEM tools are applied and combined with probabilistic fracture concepts to study in detail the influence of the scatter of material parameters and of the geometric configuration on the reliability estimations as well. The authors' aim is to show that an adequate combination of advanced experimental and simulation approaches leads to reliable results for the failure assessment and lifetime predictions of "high tech" microsystems, e.g. MEMS, in automotive applications.