Patent ID: 7321098

Claim:
A circuit board assembly comprising: a co-fired substrate comprising at least first and second regions superimposed and bonded to each other, the first region being formed of a plurality of superimposed first ceramic layers, each first ceramic layer consisting essentially of low thermal conductivity, electrically-nonconductive materials, at least some of the first ceramic layers being bonded to each other, and the second region being formed of at least one second ceramic layer containing thermally-conductive particles dispersed in a matrix comprising electrically-nonconductive materials, the thermally-conductive particles having a higher coefficient of thermal conductivity than the electrically-nonconductive materials of the first and second ceramic layers; conductor lines on at least some of the first ceramic layers so as to be between adjacent pairs of the first ceramic layers; electrically-conductive vias that extend through at least some of the first ceramic layers and electrically interconnect the conductor lines on the first ceramic layers; and a surface-mount IC device mounted to a first surface of the substrate defined by one of the low thermal conductivity first ceramic layers, wherein said first and second regions are arranged for serial thermal interconnection between said IC device and an opposed heat sink, and wherein each first ceramic layer and said at least one second ceramic layer have substantially similar width and length characteristic dimensions.