From Electric Cars to AI Servers: Packaging Concepts for Power Modules

Starting in 2027, the first IT racks in server farms will be equipped with a power output of up to 1 megawatt. For this to become possible, an important step is to convert the supply bus in the racks to 800 volts. The rapidly growing energy requirements of AI applications are bringing power electronics increasingly into focus.

In the run-up to PCIM 2026, RealIZM met Professor Eckart Hoene to speak about technological requirements, packaging concepts, and the challenges when developing power electronics for AI data centers.

Efficiency matters: Why 99 percent efficiency counts for power modules

The decarbonization and electrification of nearly all sectors of industry are powering the evolution of power electronics and creating new applications for them at the same time. Other forces at work here include the growing demand for high volumes and the pursuit of maximum efficiency, by keeping costs down and being easy on our resources.

The central question is: How can 99 percent efficiency be achieved as economically as possible? Improving efficiency by 1 percentage point saves up to €10,000 in electricity costs per device over its lifetime. With a million devices, that quickly adds up to savings in the billions. This prospect explains why industry is investing heavily in optimizing the efficiency of future mass-produced devices and why researchers like Eckart Hoene have plenty yet to discover in their development work.

Compact power modules: From car engines to AI servers

The »Power Electronics« Working Group at Fraunhofer IZM has been developing highly efficient power modules for solar and automotive drive converters for over twenty years. According to Professor Hoene, there are two main goals in their work: »Our contribution is to get the most out of semiconductors in terms of switching power. That’s why we align our designs with the current state of development of inductors and capacitors. Thanks to this approach, we can create significantly smaller power modules than was previously thought possible.«

There is growing demand for power electronics for modern server farms. Fraunhofer IZM has already completed several orders for DC-DC converters for processors, in which magnetic and thermal improvements, as well as adjustments in manufacturing, can minimize losses and maximize heat dissipation. »The technological requirements for power modules for AI data centers are more demanding than in the automotive sector. The modules must be smaller and installed in very confined spaces in server racks« Professor Hoene explains.

High-performance voltage conversion from 380 kilowatts to 0.9 volts

AI applications are causing a dramatic increase in the demand for computing power in data centers. Eckart Hoene has an example to show how: »A modern processor today requires around 1,000 amps at low voltage (0.9 volts). In a 19″ rack with 44 mm slots – each with 20 processors per slot – this results in a total power consumption of around 500 kilowatts. These 500 kilowatts on a floor space of 50 x 60 centimeters and a height of 2 meters correspond to an energy density comparable to 50 saunas. The power supply and cooling requirements are enormous. In the future, we will see 2,000 to 4,000 amps per processor. Our work focuses on the reliable, highly efficient supply of this enormous power.«

Hyperscalers today require power outputs in the range of several hundred megawatts to gigawatts – and the trend is rising. This means that they have to be connected to the extra-high voltage grid. To ensure a reliable power supply to the processor, a multi-stage voltage conversion process is used.

First, the voltage is converted to 380 volts in three-phase current – high-voltage current – using large transformers. Then, the 3-phase alternating voltage is converted to 800 volts direct current (DC). In order to efficiently transmit the high power – 500 kilowatts – the previous 48-volt supply in the server racks is no longer sufficient. The trend is moving towards 800-volt systems. Professor Hoene and his team have been commissioned to develop the necessary 500-kilowatt PFC modules (chokes) and innovative power electronics.

A simplified overview of multi-stage voltage conversion for power supply from the extra-high voltage grid to the processor in the data center

Power and cooling at a distance of 2 millimeters: Point-of-Load Converters

In another project, the researchers are building a thermally conductive point-of-load converter. It is designed to integrate five thermally conductive DC-DC converters, each with a current density of 200 amperes per square centimeter, placed directly underneath the motherboard at a distance of only 2 to 4 millimeters from the processor.

Together, they are designed to deliver the required 1,000 amperes with minimal transmission losses. »The converter combines power supply and cooling in a single component – a new design challenge, as high current density requires very high thermal conductivity« Professor Hoene explains.

Customized and agile: Knowledge cluster »Power Electronics« at Fraunhofer IZM

Fraunhofer IZM combines technological openness with development and manufacturing closely integrated. All electronic packaging technologies – including embedding, flip chip, molding, and 3D integration – are available at the Institute. Rapid iterations from initial ideas to prototypes and small-batch production are possible thanks to direct access to the machinery. Materials, component sizes, and manufacturing processes can be selected precisely according to each customer’s specifications. An interdisciplinary team of packaging specialists and manufacturing experts makes sure that know-how flows continuously in  the »power electronics« knowledge cluster, helping what is technically feasible come to life.

»Our advantage is that we are not tied to any one technology, but can find and implement the optimal solution for every requirement« Professor Hoene says about the range of services offered by his working group.

Anyone who would like to learn more about the current development projects around power modules for data centers and drive converters for the automotive industry and would like to meet the power electronics experts at Fraunhofer IZM in person will have an opportunity to do so in June 2026 at PCIM in Nuremberg.

Hall 6, Booth 260