June/July 2021

www.pcim.mesago.com PCIM EUROPE 2021 13 www.power-mag.com Issue 3 2021 Power Electronics Europe Another presentation “Challenges of New Packaging Solutions for Power Modules” was given by Ronald Eisele from Kiel University of Applied Sciences in Germany (www.fh-kiel.de ). “As many new materials solutions are developed for power electronics packaging, the material mix will continue to grow. Given the wide choice of materials, new packaging concepts can be realized to keep up with new requirements in power module packaging. Accordingly, standard applications as well as those having specific requirements can now be served by cost or performance driven demands. It is particularly important to consider the full stack of materials in the power modules to reach better thermal resistance, higher current-carrying capability, high operating temperature and improved reliability. Just a single weak material in the complete stack can deteriorate the performance of the whole module significantly. Both Si3N4- based substrates and sintering technology allow for high performance regarding reliability and heat dissipation. Thick copper-based die top connections and new inorganic encapsulation materials will complete the material stack to enable for even higher junction temperatures and power densities,” Eisele summarized. One of the three keynotes entitled “Next Generation of Power Electronics Module Packaging” by Hannes Stahr from Austrian AT&S (www.ats.net ) covered embedded packaging on the example of a SiC half-brigde. Also drive inverters can take advantage of WBG devices, as the keynote “Next-Generation SiC/GaN Three-Phase Variable-Speed Drive Inverter Concepts” by Johann W. Kolar from Power Electronic Systems Laboratory, ETH Zurich in Switzerland (www.ethz.ch) confirmed. We have summarized the major conclusions of these keynotes as well as the Best Paper – which has been traditionally supported by Power Electronics Europe – as well the Young Engineer Awards on the following pages. AS history of our Union, € 1.1 trillion. At least 30 % of this will be dedicated to climate mainstreaming. On top of that, as part of our Recovery Plan post- COVID, we have a total of € 672.5 billion to inject into the economy over the next four years. And at least 37 % must be dedicated to the green recovery. That brings the total available financial firepower to € 1.8 trillion,” added Simson. “The Green Deal has of course also a geopolitical dimension. When we presented the Green Deal Strategy, Europe was alone. The group of countries that have taken net zero commitments is now growing by the day. There is a growing momentum. And we are particularly happy that climate and energy are again a theme uniting both sides of the Atlantic. Now it is the time for a renewed EU-US ambition in energy. An energy system based on renewables will contribute to a greener, more prosperous but also more secure European and global order.” “And here comes the PCIM 2021 in play”, Leo Lorenz underlined. “The slowdown in the economy over the last years shows a diverse picture. Transportation and automation suffered from a significant dropdown, whereas the IT and consumer markets are booming due to Covid regulations such as home office and digitalization. On the other hand stimulus is coming from programs to reduce the global warming such as the European Green Deal. Power Electronics are the driving forces to meet these goals. The main technology drivers in power electronics are material science to elevate temperature behavior in all systems along with increased power density and longer lifetime. Thus PCIM focuses on pioneering work and product innovations to meet the power electronic market trends and cover the main future directions.” Material developments for power electronics A presentation, entitled “The Long Journey from Crystal Growth to Power Devices, the Role of Material Development for III-Nitride Semiconductors”, was given by Elke Meissner from Fraunhofer Institute for Integrated Systems and Device Technology (IISB) in Germany (www.iisb.fraunhofer.de ). It discussed gallium nitride (GaN) as a semiconductor material for power electronics in terms of its current applicability, it’s potential and recent shortcomings. A review of the way from crystal growth to the wafer, ready for device fabrication, was given and the bow was spanned from materials properties to device performance. “The technology of native GaN-on-GaN devices may be costly but physically right and at the end the target to go for. Defect densities and overall complexity would be drastically reduced in this case. The alternative way of heteroepitaxial growth of GaN-on-Si and the realization of AlGaN/GaN HEMTs has its own issues and limitations. The high number of defects present in the material put fundamental constraints on the reliability and final performance borders. The technology however is paving the way for the implementation of GaN devices on the market due to the much better cost efficiency and compatibility of existing fabrication equipment. A fundamental understanding of material production is essential in order to better understand and define device sensitivity related to defects and to find ways to analyze and monitor such defects in early stages of fabrication. The only way to achieve that is through a stringent correlation of material defects and device performance to be able to optimize technological processes such that production yields can be improved,” Meissner concluded. “The main technology drivers in power electronics are material science to elevate temperature behavior in all systems along with increased power density and longer lifetime. Power electronics are the driving forces to meet the goals of the European Green Deal,” stated Leo Lorenz, PCIM General Conference Director Next Generation of Power Electronics Module Packaging To improve future power modules in terms of loss reduction wide bandgap (WBG) semiconductors are well configured, especially SiC devices. The existing packaging technology limits the potential performance of WBG semiconductors. One of the best performing technologies is Chip-Embedding in order to open the path to improved performance, lifetime, power efficiency, excellent reliability and longer lifetime. Hannes Stahr, AT&S, Austria (h.stahr@ats.net ) To improve the efficiency in modern cars on the way to electromobility the power density has to increase without limitations on performance and reliability. To realize these requirements many ingredients are necessary taken into account. New module concepts with WBG semiconductors are the best candidates to face these challenges. First priority is on thermal management and handling of high currents. This requests reduction of inductance, switching losses, on-state losses of the power switches to drive the efficiency of the power modules in the upper 95 % range. The implementation of power semiconductors directly into the printed circuit board (PCB) is a very promising approach to fulfill these requirements. AT&S successfully used the expertise with its ECP (Embedded Components Packaging) technology for the implementation of efficient power packages and modules. This made it possible to reduce the space required for power packages by up to 50 % with correspondingly higher power density. In addition, it showed that very good results are achievable in terms of switching behavior, heat removal and power cycling robustness. The maturity of the