"Tiny Cooling Fan" metal-based multilayer PCB refers to a plywood backing on one side of the metal plate, heat or directly connected to an external heat sink to play fast cooling effect through the metal plate out. At present, the market has been a standard single-sided copper clad aluminum plates for sale, and the extensive use of the "Tiny Cooling Fan" switching power supply, automotive, aircraft engines drive circuit. When the high circuit density, there are double-sided SMT or THT requires many components must be used with high thermal conductivity metal core plywood to achieve. It is a good thermal conductivity metal plate embedded in the middle of a multi-layer printed circuit board, "Tiny Cooling Fan" typical structure of a metal core board itself can be use as a formation, which can be on the lower (with core insulation) of the hole through the metal interconnected, and the heat transfer in the inner layer and the surface of the metal core board through thermal vias to achieve.