Seiki Hiramatsu

Polysilane-based 3D waveguides for optical interconnects

We have been developing the optical waveguide for the multimode using the photo-bleaching property of polysilane. The refractive index of polysilane can be easily changed by exposing to UV light as photobleaching. Using this property, we can make waveguide with simple processes as spin coating, exposing and annealing. We found that this waveguide has thermal adhesive property with glass substrate. And we applied this feature to fabricate multilayered optical waveguides that have three-dimensional structure and can change the optical light at right angle.

Development of heat sink integrated transfer molded power modules with Thermal Conductive Insulating Sheet

The heat sink integrated transfer molded power module has been developed in order to improve power density for the industrial inverter power module. In the conventional case type structure, heat from semiconductor chips has dissipated to the heat sink through the grease. However, with the introduction of Thermal Conductive Insulating Sheet (TCIS) and the caulking fin base/plate fins it is possible to fabricate a grease-free structure with the new structure. Compared with the conventional structure, thermal resistance of the developed new module can be reduced 60% by utilizing the latest 12 W/(m · K) TCIS. Furthermore, power density (output power [W]/ volume [mm3]) was increased about 1.6 times due to the improvement of heat dissipation performance.

Novel IGBT modules with epoxy resin encapsulation and insulating metal baseplate

A newly IGBT module combined with liquid epoxy resin encapsulation and insulating metal baseplate (IMB) has been developed. IMB is insulating sheet with thick baseplate, and has large mounting area compared to ceramic substrate. The properties of liquid epoxy resin such as glass transition temperature, coefficient of thermal expansion, long-term thermostability are optimized for employed metal baseplate. Developed structure reduces solder cracks under semiconductor chip, and enhances lifetime of heat cycle test.

Development of compact power control unit for HEVs

This paper presents a compact power control unit (PCU) for hybrid electric vehicles. The authors use silicon carbide (SiC) MOSFET power modules with insulated ceramic substrates, resulting in high thermal conductivity. In addition, direct connection of aluminum-made chassis of a reactor and a capacitor to the heat sink makes it possible to highly release heat generation of them. These two measures enable a size reduction of the PCU, and a power density of 86 kVA/L was achieved that is the most compact in the similar PCU class.