At the same time, these MOSFETs must realize the higher power densities and better thermal performance that help designers save board space and reduce component count.
Improvements in semiconductor package technology increase reliability and support higher currents for high-power automotive applications. However, the wire bonds within traditional power MOSFET packages limit current-carrying capability and also represent a common point of failure.
While other automotive MOSFET suppliers typically employ conventional aluminium wire bonding, Toshiba is using copper connectors (copper clips) for internal bonding in large power packages such as DPAK and D2PAK.
As a result of using these copper connectors the contact area between source pad and source copper connecter is much larger than between a pad and aluminium wire bonds. This larger contact area leads to less planar current on the source pad metal layer, thereby reducing total resistance.
From both a thermal and electrical conductivity perspective copper is much better than aluminium. Higher thermal conductivity helps release heat from the connector element of the package and the lower resistivity contributes to the reduction of package resistance.
This new technique will be key to delivering the advanced MOSFETs that future automotive designs require. Toshiba has written a white paper that discusses the process of selecting advanced MOSFETs for automotive design. To download your free copy, please click here: