IDTechEx Research Asks Are Power Electronic Modules a New Growth Opportunity for Conductive Pastes

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Power electronics is a growing market thanks to the electrification of many industries including the automotive industry, as outlined in the IDTechEx Research report Conductive Ink Markets 2019-2029: Forecasts, Technologies, Players. The power electronic modulus are also growing in performance. In particular, they are becoming smaller, lighter weight, more tightly integrated and better able to handle higher power levels. In some cases, the semiconductor technology is also shifting from Si IGBT to SiC MOSFET. The dies are shrinking in area and the number of push-pull pairs in the circuit are being reduced. All these translate into higher power densities and higher operating temperatures.

In many cases, the bottleneck today is the material used in the power module package. The aluminum wire bond and the die and substrate attach are common modes of failure. The high operating temperatures push performance requirements beyond the capabilities of SAC solders. This opens the door to alternatives.

In particular, metal sintering has emerged as a promising high-performance and high-cost alternative. The most common version is based on micron-sized Ag particles and requires pressured sintering. The trend now is to improve pressure-less sintering, which is traditionally constrained to small die areas and suffers from long sintering times. To this end, nano Ag or hybrid (nano and micro) sinter particles are developed. Furthermore, there is today's innovation in form factor, going beyond pastes to offer dry films and dips to make it easier for the user to adopt. The metal sintering technology is now qualified in the automotive sector after 5-7 years of development.

Cu versions are also in competition. As usual, the promise is the same: offer the same or higher performance than Ag whilst cutting costs. The early results are promising but, as usual, Cu solutions are not a drop-in replacement since their sintering conditions are different. This year and next year will probably be make-or-break years for Cu alternatives, as serious testing is well underway.

In general, metal sintering is high-performance. The thermal conductivity is high and the melting temperature of a sintered die attach line is comparable to a solid metal, thus offering very high homologous temperatures. The cost, however, is still a significant barrier. This is both direct material costs and also the associated costs, in terms of new equipment, new required surface finishes/metallizations and so on. 

This technology is, however, now on the move. The number of suppliers has multiplied. Almost all module makers have worked with and prototyped using metal sintering solutions. As such, IDTechEx Research has assessed that the future of this market as highly promising.