Papers by Keyword: Insulated Metal Substrate

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 substrates are used in applications where electric parts generate intense heat. It is expected that the insulating layer has higher thermal conductivity as the use of an IMS is expanded. Therefore, the influence of percolation on the equivalent thermal conductivity (ETC) of an insulating layer is considered. The Effect of the volume fraction of ceramic filler on the ETC of insulating layer in IMS is investigated. The ETC as a function of volume fraction of filler is estimated. Based on these experimental and numerical results, an ETC of a filler is evaluated. The ETC of an irregular filler is presumed smaller than that of a spherical filler. It is thought that the control of filler size and shape is important for the formation of high thermal conductivity of an insulating layer. In addition, an improved equation for the ETC of IMS is proposed. The predictive values from the equation for an improved IMS agree with experimental results.

Abstract: Anodizing technique was applied to prepare insulated metal substrates (IMS) for BGA packaging. “Ideal” IMS used anodic film of aluminum as the insulating layer instead of epoxy, which led to higher thermal conductivity. But the thermal shock resistance of IMS is poor because of the great difference of thermal expansion coefficient between aluminum and its anodic film. In this study, different anodizing processes of aluminum were analyzed. The parameters, which can affect the thermal shock resistance of IMS, especially the surface temperature of Al substrate, were studied. The anodic film obtained with the optimized parameters of anodizing process had excellent performance, such as the resistivity was over 1013Ω·cm, the breakdown voltage was higher than 600V, and the most important thing was that it could resist thermal shocks between room temperature and 300°C. Then BGA packaging was successfully performed based on this IMS.