Improving the Thermal Conductivity by Varying the Filler Geometry of Copper in Thermosets

Thermal management is rising in importance due to the evolving requirements of electronic devices, namely, compactness and performance. Polymers, particularly thermosets, exhibit low thermal conductivity, so that fillers are required to enhance the performance of thermosets and make them suitable for such applications. So far, various factors have been investigated in order to improve the thermal conductivity of thermosets, mainly based on single-filler systems. Given the variation in the geometry of different filler types, suggestions about the influence of geometry have also been made. However, the impact of the geometry of the filler type is rather unknown. Therefore, this paper investigates the use of copper (Cu) as a filler with high thermal conductivity and examines four different geometry types (three sphere types with different sizes, as well as platelets) in terms of their reaching a higher thermal conductivity in an epoxy matrix. Cu platelets showed the highest thermal conductivity values, even though they also exhibited high anisotropy. To understand their material behavior in more detail, a new method of inline viscosity measurement is further evaluated. This method allows consideration of local flow conditions and is therefore more precise than methods based on complex viscosity.