부산대학교 도서관

The consideration of package-induced effects during the design process of MEMS sensors is still insufficient. A method for predicting the influence of the packaging and assembly process on the performance of a Hall sensor is described. The geometry of the device, the behaviour of the packaging materials as well as the packaging process are regarded using this method. The complex material behaviour of adhesives and moulding compounds was investigated. The results show, that for modelling the influence of the packaging on the sensor performance correctly, the nonlinear temperature- and time-dependent material behaviour has to be taken into account. Differences of the coefficients of thermal expansion of the packaging materials lead to thermo-mechanical stress in the package. Due to the time-dependent material properties, this results in a change of the offset and the sensitivity of the sensor over time and may lead to a sensor working outside its specification. The piezoresistive and piezo-Hall coefficients of semiconductor Hall plates were measured, thereby the stress- and temperature-dependency of the Hall plates were determined. According to the results, package-induced stresses lead to a change of the offset voltage up to 60 % full-scale while the sensitivity changes by ±4 %.