Embedding SiC in the PCB changes the inverter's current path
Illustrative image: Unsplash contributor on Unsplash
Infineon's ENDOPACK Cell embeds 1,200 V silicon carbide MOSFETs in the PCB, shortening the connections through the power stage and allowing the devices to be arranged around the inverter's layout rather than the dimensions of a module housing.
With SiC, the space occupied by those connections has a direct effect on switching behaviour. Parasitic inductance produces a voltage proportional to the rate of current change, so a mechanically convenient connection can introduce enough overshoot to force a slower switching edge. The circuit then gives up some of the performance for which the SiC device was selected. Infineon reports inductance below 2 nH for its embedded architecture, compared with 20 nH in its reference comparison. At an illustrative current slew rate of 1 A/ns, those inductances would contribute 2 V and 20 V respectively. The calculation describes the inductive contribution at that assumed slew rate; actual switching waveforms depend on the rest of the circuit.
The gate return still needs its own attention because current transients can disturb the drive voltage even when the main power connections are short. Infineon's separate SiC layout guidance discusses Kelvin source connections for precisely this reason: separating the gate reference from the load-current path helps prevent the load's changing current from interfering with the gate drive.
Building the power package into the board
Embedding the semiconductor also makes the PCB part of the power package, bringing board fabrication and inspection into the design of the switching assembly. The route out for heat, access for fault diagnosis and the handling of a defective board become part of the comparison with packaged devices. A layout change can therefore reach beyond the electrical drawing into how the assembly is made and serviced.
On the production side, several ENDOPACK cells can be incorporated in one board, with their number and position adapted to the required power. That could allow parts of an inverter architecture to be reused across vehicle platforms while the board geometry changes to suit the available space. Infineon says ENDOPACK Cell is ready for mass production, with vehicles using it planned for 2027.
The company's wider performance claims need to be read against their individual conditions: some efficiency figures refer to a driving cycle, while power-density estimates include prototype and simulation data. The reported reduction in inductance gives a more direct account of what the packaging changes electrically, since it reduces the unwanted voltage generated by a given change in current. Turning that advantage into a production inverter still involves the gate circuit and the board's thermal design.
Sources
Image: Copper winding and components on a printed circuit board. Illustrative stock photograph; ENDOPACK Cell is not shown. Photo: Ludovico Ceroseis / Unsplash. Image source. Unsplash Licence.
