Review of silver nanoparticle based die attach materials for high power/temperature applications

There has been a significant rise in the number of research papers on silver nanoparticle based solutions for harsh environment die attach. However, sintering nanoparticles is a complex process, affected by many different factors, such as the sintering temperature profile, particle size, sintering pressure, sintering environment, and organic compounds inside the nanoparticle paste used for stabilisation of the particles and easier processing. Therefore, numerous routes exist for establishment of sintered structures, and each lab has selected their own techniques and criteria for sintering silver nanoparticles. This has resulted in formation of a significant amount of knowledge and data in this field, but without appropriate correlation between utilised parameters. In this review data has been collected from a wide range of researchers in the field and an attempt made to correlate the results. By finding connections between the datasets, we present a broad and general understanding of the sintering processes to help researchers produce desired sintered structures. The collected data and investigated parameters include sintering pressure, metallisation, effect of thermal aging and cycling, highest sintering temperature, and particle size distributions. Some particularly interesting innovations in the field to address the shortcomings of sintering silver joints are investigated and some insights on sintering process are also provided, such as the understanding that higher sintering pressure causing improved strength might potentially reduce the long term thermal resistance of the die attach.