Abstract
An insulated metal substrate (IMS) is a circuit board comprising an insulating layer on a metal base plate. The insulating layer is made from epoxy resin incorporating dense ceramic fillers. The thermal conductivity of the insulating layer is calculated from measurements of the thermal resistance of the substrate. The influence of percolation on the thermal conductivity of an insulating layer is considered. The thermal conductivity as a function of the volume fraction of filler is estimated. Based on these experimental and numerical results, the equivalent thermal conductivity of the filler is evaluated. It is thought that the control of filler size and shape is important for the achievement of high thermal conductivity of an insulating layer. In addition, an improved equation for assessing the thermal conductivity of an IMS is proposed. The predictive values agree with experimental results.
