With the development of science and technology, the scope of application of the polyimide film has been greatly expanded. In addition to functioning as a thickness of the insulating material is 25 ~ 150μm self-supporting film, there are bound to the substrate film. The thickness of these films can reach several angstroms to several microns, i.e., a so-called monolayer film. In addition to being the first to enter the industrialization of the polyimide insulating film as a magnet wire insulation coating outside. A variety of flexible printed circuit board copper clad polyimide has become a huge industry, growing at 10 percent annual growth rate. As a matter of film dielectric material should be concerned about in addition to thermal stability, mechanical properties, and thermal expansion coefficient, and the base material of adhesive and dielectric constant.