OREANDA-NEWS. Thanks to a new packaging and interconnection technology (PIT), it is now possible to manufacture electronic power modules that operate reliably even at temperatures as high as 300 degrees Celsius. The new PIT is the outcome of the recently concluded three-year Hot Power Connection (HotPowCon) research project, which received funding from the German Federal Ministry of Education and Research. Since control electronics have to cope with very high operating temperatures, especially in hybrid and electric vehicles, the new PIT will serve as an important foundation for the further development of electromobility in Germany.

Saving energy and cutting costs

Electronic power modules such as inverters, DC/DC converters, and battery chargers are key components in electric vehicles. To push electromobility into the mainstream, the automotive industry needs power modules that are as inexpensive, energy efficient, and compact as possible. It also has to be possible to integrate logical entities such as microprocessors into the modules in order to enhance their functionality. Until now, there was no lead-free, reliable, and inexpensive PIT that was suitable for these combined logical power modules and could withstand their high operating temperatures. Existing joining techniques were either extremely expensive or used lead-based solders that harm the environment. What is more, power modules required complex cooling processes to manage the heat they generate as a result of working with high electrical output. The choice of joining technique determined the upper limit to their operating temperature.

Prepared for large-scale series production

The HotPowCon consortium has now developed a system of workable tin-based pastes that permits joining by way of isothermal solidification. This means all the module's components can be soldered in a single joining process. The new PIT is lead-free and based on inexpensive materials. Because it can withstand very high temperatures, it greatly reduces cooling requirements. That in turn reduces power consumption and helps to cut costs. In their work on this PIT - choosing what materials to use and developing the necessary process and plant technology - the researchers paved the way for it to be used in industrial series production. They used demonstrators to show that the PIT is reliable at high temperatures.

Multidisciplinary research team

HotPowCon brought together large companies, medium-sized enterprises, universities, and research institutions. Robert Bosch GmbH led the project, and partners included Siemens AG, Heraeus Materials Technology GmbH & Co. KG, Chemnitzer Werkstoffmechanik GmbH, Seho Systems GmbH, the Institute of Applied Systems and Circuits at the University of Rostock, the Center for Microtechnical Production at the Dresden University of Technology, and the Fraunhofer Institutes for Reliability and Microintegration IZM and for Electronic Nano Systems ENAS. Daimler AG and Volkswagen AG were associate partners. The German Federal Ministry of Education and Research provided around half of the project's budget of 5.5 million euros, funding the HotPowCon project as part of its “IKT 2020” research program. The newly developed PIT is also suitable for use in manufacturing inverters for photovoltaic systems, and will find application in other sectors in the future.