"Tiny Cooling Fan" and the bottom of the heat generating element by thermal vias soldered directly to the plate surface, the heat generated by the heat generating device is directly transmitted to the metal core board, a metal core sheet to pass through the installed enclosure of the contact holes to dissipate heat conduction; heat larger core can be milled to both sides of the insulation layer, through the edge of the exposed "Tiny Cooling Fan" base contact with the metal core cooling, so it has good heat dissipation. On the chassis in a closed cooling circuit is a good choice of metal core PCB usually have a core material of aluminum, copper, steel, etc., and later developed a copper-clad Invar composites (CIC), which not only has good thermal conductivity sex, and "Tiny Cooling Fan" coefficient of thermal expansion of the semiconductor device matching, CIC made of metal core can be applied to the requirements of high reliability, high packing density, high-power, high-performance military electronic equipment.