Integrated SiC power module on ceramic heat sink launched

Cooling the power electronics in powertrains is key when it comes to reliably regulating the electrical power in e-drives on an ongoing basis and over longer periods of time in the smallest possible space. Together with the Fraunhofer Institute for Integrated Systems and Device Technology (IISB) in Erlangen, CeramTec has developed an innovative cooling solution for power electronics in e-mobility.

The joint project, called FuCera, focused on the development of a module design using ceramic coolers that efficiently deheats the SiC semiconductor chips and makes the best possible use of the chip surface.

High-performance ceramics are extremely suitable for the use in e-mobility due to their properties, namely the resistance to temperature changes, chemical resistance, electrical insulation, corrosion and wear resistance combined with their thermal conductivity.

Ceramic heat sink with chip-on-heatsink technology

For efficient heat dissipation and thus better thermal management, CeramTec uses ceramic heat sinks with metallisation on both sides, which makes it possible to apply the semiconductor chips directly to the ceramic cooler (chip-on-heatsink). This design makes it possible to use both sides as circuit carriers and to cool them at the same time. The internal cooling structure can be individually adapted to the requirements and designed, for example, as a pin-fin structure. In a direct performance comparison between conventionally constructed cooling systems and heat sinks with CeramTecs chip-on-heatsink technology, the thermal resistance of the latter is only half the value.

The chip-on-heatsink design was also applied to the new SiC power module with integrated ceramic cooler. The cooler consists of a liquid-flow aluminium nitride cooler with copper metallisation on both sides and an optimised pin-fin structure. The very compact heat sink has a size of only 48x36mm with a thickness of 3.6mm (incl. metallisation) and a weight of ten grams.

Test measurements confirm thermal performance

The thermal performance of the module was impressively confirmed by thermal characterisation at the PowerCycling test station. At the design point, the thermal resistance of the power module with pin-fin ceramic cooler is 0.15 K*cm²/W from the chip to the cooling water. The small and lightweight design of the cooler and its internal pin-fin structures are well suited for mounting semiconductors using pressure sintering. This was proven in practice both by calculation and by means of the assembled power modules. Good sintering properties of the cooler metallisation were demonstrated by shear strengths of approximately 40 MPa.

"The test measurements have proven that the SiC power module with high-performance aluminium nitride ceramic cooler can withstand high loads. With low thermal resistance and high packing density, the power module for drive inverters becomes a high-performance cooler for e-mobility that can additionally be modified for specific customer requirements," said Richard Boulter, President Industrial of the CeramTec Group.