Today epoxy glass cloth sheet "Micro Cooling Fan" heavy use, the thermal conductivity of a surge of 0.2W / m ℃. General electronic circuits due to the small amount of heat, usually epoxy glass cloth substrates produced a small amount of heat generated by traces the general thermal design and components dissipate itself. With the "Micro Cooling Fan" component miniaturization, high integration, high frequency, thermal density was significantly increased, especially in the use of power devices, in order to meet this high cooling requirements and later developed some new thermal conductivity sheet. As US-developed T-Lam plate, which is filled in the resin of the boron nitride powder of high thermal conductivity, so that "Micro Cooling Fan" thermal conductivity improved to 4W / m ℃, ordinary epoxy glass cloth substrate 20 times.