Key Research Areas

The energy transition is one of the greatest challenges of our time. A key factor for its success is the efficient use of electrical energy, whether in household appliances, industrial plants or electric vehicles. A promising approach to increasing efficiency lies in the further development of power semiconductors, particularly through the use of low-inductance power modules with silicon carbide (SiC) technology.

Power modules as the key to efficiency

Power modules are crucial components in power electronics, as they are responsible for controlling and converting electrical energy. Compared to conventional silicon-based components, wide band gap (WBG) semiconductors such as SiC enable significantly higher efficiency, lower losses and higher switching frequencies. These advantages lead to more compact and powerful systems, which are used in particular in electric cars and renewable energy systems.

An innovative, low-inductance B6 bridge was developed as part of a study by Fraunhofer IZM and Rogers Germany. This new type of module relies on a microchannel cooler integrated into the ceramic substrate with direct water cooling to provide significant thermal advantages over existing power module solutions.

Technological innovations of the SiC-B6 bridge power module

The power module presented here fulfills key requirements for high-performance applications:

1. Optimized heat dissipation

• The module is based on a microchannel cooler (MCC) with direct water cooling.
• Size of the mold body: 43.6 mm x 89.5 mm x 5.0 mm
• The thermal resistance is minimized by a combination of silicon nitride (Si₃N₄) and the copper layers.
• The thermal resistance is exceptionally low at R_th = 0.475 K/W per chip, so that high power densities can be realized.

2. Minimization of parasitic inductances

• The design dispenses with classic wire bond connections and relies on copper clips.
• Optimized internal wiring achieves a switching cell inductance of 3.4 nH
• The low-inductance design reduces switching losses and enables higher switching frequencies.

3. Integrated silicone cap technology from muRata

• Currently approx. 4 nF per phase - damping of oscillations during the switch-off process possible
• With higher available capacitance, it could also significantly reduce the switch-off overvoltage

Advantages for electric cars and renewable energies

The properties of this low-inductance SiC-B6 bridge power module make it particularly attractive for applications in electromobility and renewable energies.

• Electric vehicles benefit from the higher efficiency, as lower losses and more compact designs, which increase the range and reduce the load on the cooling system.
• Inverters for photovoltaic systems can operate at higher switching frequencies, which reduces the size and cost of filter components.
• Grid-connected battery storage systems are more cost-effective overall thanks to their low power loss.

Conclusion and future prospects

The further development of low-inductance power semiconductor modules based on SiC represents an important step towards increasing efficiency in the energy transition. The technology presented here impressively demonstrates how innovative packaging concepts and optimized circuit designs can lead to significant increases in performance. Future developments should focus on increasing the capacity of the silicon capacitors so that the switch-off behavior can be optimized as well as a cost-efficient series production.

The consistent further development of these technologies will be crucial to successfully mastering the challenges of the energy transition.