PURPOSE: To form a second opening part whose side face is of a gentle forward taper shape and to make disconnection of a second conductive-layer pattern hard to occur by a method wherein, after a first photosensitive polyimide layer has been half cured, a second photosensitive polyimide layer is exposed, developed and fully cured and the second opening part 6 is formed.

CONSTITUTION: A photosensitive polyimide is coated in such a way that a first photosensitive polyimide layer 3 and a first opening part 4 are covered; it is prebaked (e.g. at 60 to 70°C for 10 minutes); a second photosensitive polyimide layer 5 whose film thickness is, e.g. at 10 to 20 μm is formed; after that, in a region on a first conductive-layer pattern 2a, the second photosensitive polyimide layer 5 is exposed (to h-rays + g-rays at 100mj/cm2), developed (e.g. by using an NMP solvent) and fully cured (e.g. at 400°C for 30 minutes). Thereby, a second opening part 6 whose width is larger than the width of the first opening part 4 revealing the first conductive-layer pattern 2a and whose side face is of a forward taper shape at about 45° is formed via the first opening part 4.