To solve the problem with a conventional heat dissipation substrate, wherein an increase in the content of an inorganic filler to improve thermal conductivity easily causes coarse surface of a heat transfer layer, resulting in deterioration in bondability between the heat dissipation substrate and a leadframe embedded therein or a wiring board, thereby causing influence on electric insulation.
The heat dissipation substrate 101 includes a metal plate 108, a sheet-like heat transfer layer 102 which is formed on the metal plate 108 and contains a crystalline epoxy resin, and a wiring board 104 and a leadframe 103 which are fixed to the heat transfer layer 102. In the substrate 101, the content of the inorganic filler 126 in the heat transfer layer 102 is ≥66 vol.% and ≤90 vol.% and a recess 110 is formed adjacently to the wiring board 104 or the leadframe 103. Thus, even if the content of the inorganic filler 126 is increased, the surface 123 of the heat transfer layer 102 is prevented from being coarse and the highly correct positioning and excellent electric insulation can be obtained.
TSUMURA TETSUYA
NISHIYAMA KIMIHARU
Daisuke Nagano
Kentaro Fujii
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