Next-gen thermal management Thermal Interface Material for Batteries in the field of electric cars

The switch to electric drive systems and the increasing variety of sensors and electronics imply completely new challenges for the automotive sector. Besides the field of electric powertrain, the battery is one of the most critical parts of the EV or PHEV. A perfect temperature control is crucial and therefore, the selection and integration of thermal interface materials is mandatory. Of course, there are many different types of

battery cells, modules, manufacturers and requirements on the market, which vary widely. That in turn leads to a lot of different thermal management solutions that can be applicated. A common solution can be, to transfer the heat of the cells to the bottom of the module and to connect these cells with a Gap Pad, which is compensating any kind of mechanical tolerances. The heat transfer from the cells to the bottom can be realized by a thermal tape, that combines a good thermal conductive with high electrical isolation. Furthermore, a thermal connection to the side of the module by a Gap Pad can be useful, to ensure a perfect cooling of the whole module. In view of these requirements, Kerafol offers a wide range of different Thermal Interface Materials. For the Gap Pads, the focus is on thermal performance, softness and mechanical stability. It is important to know, that the thermal performance of the whole application is not only depending on the thermal conductivity of the pads, it is about the total thermal resistance of the construction. Besides the thermal resistance of the pad, there is always a thermal resistance between pad and heat source and heat sink. So it depends on the ability of the material, to get a smooth levelling and perfect contact to the surface. Of course the selection of the right pad depends on the application, but a very common solution can be the 86/225 or the 86/325, both based on silicone for the highest level of flexibility.

For the thermal tape between the cells, the 86/60 can be a very good match, as this material combines a high thermal conductivity of 4,5 W/ mK with an electrical isolation of 5 kV by a thickness of 0,25 mm.

The long-term behaviour of all components in that kind of application, that applies also for of the thermal interface materials, is crucial. Tests like maximum temperature, temperature cycles, humidity in combination with temperature or of course vibration tests can give a first indication to the behaviour and quality of the material. Therefore, Kerafol can look back on more than 20 years experience of R&D, testing and producing of thermal interface materials. Whether battery, or electric powertrain - The German technology TIMs of KERAFOL are already an approved solution for a wide range of automotive applications. This is enhanced with rapid turnaround and development support from UK based Thermal Issues, supplying TIM’s, electrical isolation, RFI and IP rated gasket options.

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Components in Electronics

July/August 2020 49

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