Under the "220V Cooling Fan" given conditions, when the circuit board components temperature rises above the temperature of reliability assurance, we have to take appropriate countermeasures cooling to reduce the temperature to within the working range reliability, this is what we make the ultimate purpose of thermal design. "220V Cooling Fan" heat is the main content of PCB thermal design. For the PCB, its nothing less than the three basic types of each heat conduction, convection and radiation. Is the use of electromagnetic radiation by the movement of the heat out of space, the smaller its cooling capacity, usually as a means of auxiliary heat. "220V Cooling Fan" heat conduction and convection are the main means of cooling methods we used each radiator heat conduction from the heat source, the use of air convection dissipate.