Research progress of force-induced oriented highly thermally conductive polymer composites

With the rapid development of semiconductor manufacturing technology, the miniaturization and integration of electronic equipment make the heat dissipation becoming a key factor restricting the development of electronic components, and higher requirements have been placed on the thermal conductivity of thermal interface and packaging materials. Simple blending between thermally conductive filler and polymer matrix is difficult to achieve high thermal conductivity at low filling levels. Orientation of thermally conductive fillers in polymer matrix is favorable for achieving anisotropic thermal conductivity and reducing the thermally conductive permeation threshold, therefore, how to construct an oriented structure of thermally conductive filler in the polymer matrix to form an efficient thermally conductive network at low filling levels is becoming a research hotspot. In the process of promoting the orientation of thermally conductive fillers, especially fillers with nonspherical characteristics (flaky, rod-shaped or fibrous, etc.), external force plays a vital role. This article is classified according to the main driving forces that induce the orientation of thermally conductive fillers, and summarizes the latest technology and research progress in the preparation of anisotropic polymer matrix composites with high thermal conductivity, using magnetic field induction, electric field induction and mechanical force induction in the past 5 years. The conditions, mechanism of forming oriented structure of conducting filler under the action of external forces, and the structure-property relationship are mainly introduced. The characteristics, advantages and disadvantages of each method are analyzed. The bottlenecks in constructing an oriented structure of thermally conductive filler in the polymer matrix are analyzed simultaneously so far. Finally, the future development direction of thermally conductive polymer composites is forecasted. This review provides a reference for the development and application of highly thermally conductive, anisotropic polymer composites at a low filler loading level.