Influence of Ambient Temperature on Radiative and Convective Heat Dissipation Ratio in Polymer Heat Sinks

Thermally Conductive and Electrically Insulating Polymer-Based Composites Heat Sinks Fabricated by Fusion Deposition Modeling

This study explores the potential of novel boron nitride (BN) microplatelet composites with combined thermal conduction and electrical insulation properties. These composites are manufactured through Fusion Deposition Modeling (FDM), and their application for thermal management in electronic devices is demonstrated. The primary focus of this work is, therefore, the investigation of the thermoplastic composite properties to show the 3D printing of lightweight polymeric heat sinks with remarkable thermal performance. By comparing various microfillers, including BN and MgO particles, their effects on material properties and alignment within the polymer matrix during filament fabrication and FDM processing are analyzed. The characterization includes the evaluation of morphology, thermal conductivity, and mechanical and electrical properties. Particularly, a composite with 32 wt% of BN microplatelets shows an in-plane thermal conductivity of 1.97 W m-1 K-1, offering electrical insulation and excellent printability. To assess practical applications, lightweight pin fin heat sinks using these composites are designed and 3D printed. Their thermal performance is evaluated via thermography under different heating conditions. The findings are very promising for an efficient and cost-effective fabrication of thermal devices, which can be obtained through extrusion-based Additive Manufacturing (AM), such as FDM, and exploited as enhanced thermal management solutions in electronic devices.

Numerical Computation of Anisotropic Thermal Conductivity in Injection Molded Polymer Heat Sink Filled with Graphite Flakes

The use of polymer composites as a replacement for commonly applied materials in industry has been on the rise in recent decades. Along with the development of computer software, the desire to predict the behavior of new products is thus increasing. Traditional additives in the form of fibers cause anisotropic properties of the whole product. The subject of the presented study is a polymer heat sink prototype with a thermally conductive filler in the form of graphite flakes, which differs from the commonly used fibers. Three simplified approaches are introduced to model the thermal conductivity anisotropy of an entire heat sink. Each model is subjected to an inverse heat conduction problem, the output of which are thermal conductivity values. These are optimized to minimize the difference between simulated and experimental temperatures at selected locations in the model. The approaches are compared with each other with respect to their error against the experimentally obtained results. The goal is to find a sufficiently simplified approach that can be applied to products of various geometries. This would remove the costly and time-consuming need for mold production and experimental testing.