Solder behavior and defect formation in joining process by Al/Ni self-propagating reaction

Joining methods based on self-propagating reaction have been presented in the field of electronic packaging to solve the mismatch of CTEs (Coefficient of thermal expansion) among materials. As a key factor for joining reliability, the defects should be minimized to obtain the sound and reliable solder joints. However, due to the very fast heating and cooling speeds, the solder behavior and the formation mechanism of defects in self-propagating joining are different from that in traditional joining methods. In this study, the interfacial IMC morphology, defects in joints and the fracture behavior had been characterized to enable an analysis and evaluation of the solder behavior and formation of defects in self-propagating joints. In addition, the influence of material properties, applied pressure and ambient temperature had been investigated which can assist further optimization of process and the joining quality.