Next-Generation PPS Grades for Power Module Applications

Conference: PCIM Europe 2018 - International Exhibition and Conference for Power Electronics, Intelligent Motion, Renewable Energy and Energy Management
06/05/2018 - 06/07/2018 at Nürnberg, Deutschland

Proceedings: PCIM Europe 2018

Pages: 4Language: englishTyp: PDF

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Schirmer, Christian; Ota, Yuki (Toray Resins Europe GmbH, Germany)

Polyphenylene sulfide ("PPS") is a high performance thermoplastic material widely used for injection molded housings for transportation and industrial power modules and inverters. It has well established heat and electrical resistance characteristics, important for these applications. In particular, power module housings have exposure to cycles in temperatures during loading and discharge of electric power and required materials with superior durability to the high voltages and toughness to withstand the expansion and contraction from the temperature swings. Future generations of power modules are evolving with the trends toward miniaturization and higher voltage & power requirements for example in electric vehicles with 48volt systems, longer life battery capabilities and less weight. As power modules are becoming smaller and the distance between exposed metal conductors imbedded in the housing is shortened, the requirements for high voltage tracking resistance of the housing are raised. Current generation modules require CTI rank 3-4. Increasingly, future modules are requiring CTI rank 0 (600V). PPS inherently has an excellent dielectric breakdown voltage. However, its chemical structure can carbonize at extremely high temperatures. High tracking resistance is achieved by reducing or delaying the carbonization process. Based on analyzing the carbonization fracture mechanisms in PPS, Toray has developed the following method to increase the tracking resistance in PPS and has already developed and launched PPS grades with the highest tracking resistance ranking (CTI rank = 0, 600V), A second trend in future power modules is the increasing peak temperature in the thermal cycle and the requirements for the housing material to be durable to resulting increased thermal expansion and contraction. Furthermore, these housings are typically over-molded over the metal conductors and bolts where thermal expansion compatibility of the housing material and the metal is essential to avoid cracking or delamination. In this presentation, we would like to report about new PPS materials developed to increase toughness and durability to this higher heat cycle while maintain the leading CTI = (600V) tracking performance.