Reliability Analysis of a New Soldering Process For Automotive Power Modules Application

This paper presents a reliability study of power assemblies based on the correlation of finite element simulations and experimental results. For these power modules, a new process was used to solder bare dice on a copper lead frame with a local heating source. The reliability methodology we are using is based on the evaluation of the strain energy density accumulated in the solder joint during the lifetime of the assembly. The study was also carried out on various types of solder. Two series of simulations have been carried out in parallel. The first series was the simulation of a classical reflow process with a uniform temperature of 300°C in the whole assembly. The second one was the simulation of the new process with localized heating. The comparison of the results of the simulations allowed to conclude that this new process does not introduce more strain than a normal process. In order to evaluate the lifetime of the assembly, ageing tests have been carried out on representative test vehicles. By correlation between simulations and ageing tests, we have evaluated the lifetime of the assembly under operation conditions.