| 摘要 |
PURPOSE:To protect an insulating layer against bulging caused by coating failure so as to form a thick insulating layer excellent in coating properties by a method wherein photosensitive polyimide of low viscosity and photosensitive polyimide of high viscosity are applied in succession lapping over. CONSTITUTION:A photosensitive polyimide 4 of low viscosity is applied onto the surface of a board 1 through a spin coating method, immediately a photosensitive polyimide 5 of high viscosity is applied thereon through a spin coating method, and the laminate concerned is dried up at a low temperature. Through this lap coating, a fine wiring pattern 2 is improved in coating properties by the photosensitive polyimide 4 of low viscosity, an insulating film can be formed thick by the photosensitive polyimide 5, and the surface of the insulating film can be made flat. Then, the surface of the photosensitive polyimide film is irradiated with ultraviolet rays S through a glass mask 6 provided with a shielded part 6a so as to enable the required part of the surface of the photosensitive polyimide film to be irradiated with light energy, and the substrate 1 is dried up at a low temperature. The dried substrate is developed to remove the non-irradiated part of the polyimide film 5 for the formation of viaholes 7. |
