Thick Film Sensor Manufacturing Techniques for Realization of Smart Components via Low Pressure Die Casting

Abstract

Recent developments like autonomous driving have increased the interest of the automotive industry in structural health and condition monitoring of safety-relevant components often manufactured via High or Low Pressure Die Casting (HPDC, LPDC). Specifically the latter process is important in this field as the improved quality of castings produced facilitates T6 heat treatments aimed at optimizing mechanical performance of such components. The specific challenge associated with this approach is that it produces critical thermal loads which may compromise the characteristics of the integrated sensor. The present study shows the results obtained by LPDC on thick film sensor systems prepared by means of screen printing on aluminum substrates. The response of the sensor systems to the thermal loads associated with the casting process is evaluated in casting experiments, with temperatures reached during casting checked by means of thermocouples attached to the inserts. The focus is on the influence on general properties of the piezoresistive sensors as well as on their response to thermal and mechanical stimuli. The results show that in contrast to HPDC, in the case of LPDC, the former provides stimuli for thermally induced processes which can compromise sensor layers. The respective trends have been studied via resistance measurements on samples subjected to repeated firing cycles and actual casting experiments.