Investigation of Two-Stage Ag-Sintering Processes for the Die Attach of Power Devices

In this paper, a Two-Stage sintering process is investigated to optimize sintering production lines for the die attach of power semiconductor devices. In the Two-Stage sintering approach, the conventional pressure-assisted sintering process is divided into a short pressure sintering stage and a subsequent longer heat treatment stage. By varying the process parameters in both sintering stages, a total of 99 parameter combinations were tested, using commercially available diodes and substrates. The resulting sintered joints were examined by mandrel bending test and cross-section analysis with scanning electron microscopy (SEM). The results show that by implementing the Two-Stage concept, the process parameters in the pressure sintering step can be significantly reduced, enabling both significantly lower pressure and a shorter process time of only 15 s. Thereby the throughput of the costly pressure sintering process could be significantly increased, resulting in a more cost-efficient overall production of sintered power modules.