High Out-of-Plane Thermally Conductive Polyimide Film for Electronic Thermal Management by the Incorporation of Core-Shell Ag/Polyimide Microparticles

Polyimide (PI) films with high out-of-planethermal conductivityarehighly desirable for effectively alleviating thermal failure in advancedflexible electronics. However, it is still a great challenge to achievehigh out-of-plane thermal conductivity with a low filler content bya simple method. Herein, an Ag-coated PI microsphere (PIM@Ag) as athermally conductive filler with a considerable heat-transfer pathin the out-of-plane direction is prepared to improve the out-of-planethermal conductivity of the PI film. Because of the introduction ofthermal welding between Ag nanoparticles during thermal imidizationfurther eliminating the interface thermal resistance, the resultantPI/PIM@Ag composite film exhibits a high out-of-plane thermal conductivityof 1.2 Wm(-1)K(-1) with an ultralowAg content of 6.08 wt % and a superior tensile strength of 124.0 MPacompared to 78.9 MPa of a pure PI film. Practical application andcomsol simulation results verify that the PI/PIM@Ag composite filmhas excellent heat dissipation ability for a chip. This work providesan idea for improving the out-of-plane thermal conductivity of polymerswith low filler contents.