Insulating Property Estimation Using Q(t) Method of tpPI/hBN Composite Materials Produced by Electrostatic Adsorption Method

A composite material with higher thermal conductivity and acceptable breakdown strength has been developed. An electrostatic adsorption method produced a thermoplastic polyimide (tpPI)/ hexagonal boron nitride (hBN) composite to create a thermally conductive composite insulating material. The flaky surface of the hBN particles was oriented vertically to the sample thickness direction (CMV sample) or parallel to the sample thickness direction (CMP sample). The transferred/accumulated charge amount was measured using the Q(t) method to understand the insulating property. As a result, the charge amount ratio (Q(300)/Q0(2)) of the CMP sample at 30°C is higher than that of the CMV sample. In addition, the temperature-dependent transferred/ accumulated charge amount of the CMP sample was also comparatively higher than that of the CMV sample. This is probably attributed to the tpPI/hBN interface, a potential electrical weak point, and is parallel to the CMP sample's thickness (electric field) direction.