Characterization of adhesives and interface strength for automotive applications

Epoxy-based adhesives are used as thermal and electrical interfaces. These interfaces require excellent adhesion, heat transfer, and electrical properties. Due to the difference in material properties, adhesive failure and delamination remain an integral part of the reliability issue since adhesive rupture or delamination may induce other electrical or mechanical failure mechanisms. Aim of this work is to characterize material properties which will be used for prediction of interface toughness with the help of finite element analysis. Focus will be given to the interfaces between the adhesives and brittle materials (silicon and alumina). In-depth material characterization is conducted by differential scanning calorimetry (DSC), pressure-volume-temperature (PVT) measurements and dynamic mechanical analysis (DMA) in order to calculate the residual stresses at the interface due to curing and cooling. The heat of reaction for adhesives, kinetic investigation results, relation between cure shrinkage and conversion level, bulk moduli as a function of temperature and elastic moduli as a function of temperature and time will be presented.