Since the beginning of 2015, the halogen free flame retardant (HFFR) polybutylene terephthalate (PBT) Ultradur B4450 G5 from BASF has been used in the mass production of the MiniSKiiP Dual power semiconductor modules from the company Semikron.
Application examples of power semiconductor modules (or DC/AC converters) are in industrial drive technology, solar inverters, or in the powertrain of electric vehicles.
Developing heat is dissipated from the modules by metallic heat sinks. This prevents any rise in temperature and helps to ensure an optimum operating temperature.
The power semiconductors are protected from external influences such as moisture, dirt, and fluctuations in temperature by a housing made from the thermoplastic Ultradur.
The material is classified as V-0 under UL 94 from a wall thickness of 1.5mm. With high temperature performance (RTI=140°C), it is particularly suited to applications in electric power modules which are subject to a high amount of heat generation. The thermoplastic also has good mechanical properties and can be light-colored.
With a CTI value of 600, Ultradur offers good electrical insulation capacity and therefore offers greater freedom of design for small and detailed components such as the MiniSKiiP Dual, noted BASF.
Moreover, Ultradur B4450 G5 is reinforced with 25% glass fibers, which gives the components additional stability.
“Thanks to the positive cooperation and the professional support we have received from BASF in respect of application development and simulation, we have managed to manufacture components which are not just extremely stable, but also display a very low level of wear for a material that is reinforced with glass fibers,” said Dr.-Ing. Jörn Grossmann, New Technologies Material Expert at Semikron.
Ultradur B4450 G5 is hailed for its effective prevention of electrolytic corrosion. Metal contacts which are installed are only affected to a small extent even under highly humid and warm conditions. This means that short-circuits and the damage resulting from this can be avoided.
Semikron and BASF have previously developed a new kind of test method which can be used to test BASF’s thermoplastics for their resistance to electrolytic corrosion.