| 摘要 |
PURPOSE:To form a high-accuracy resist pattern and to obtain a printed wiring board whose reliability is excellent by a method wherein a photosensitive etching resist material with which a copper foil on an insulating substrate is coated is irradiated with ultraviolet rays via a diffusion mask film formed on the surface of a mask film and the material is exposed to light. CONSTITUTION:A diffusion film 3 through which light having a wave-length suitable for hardening a photosenstive etching resist material can be transmitted is pasted, via an adhesive layer 4, on the face on the incident light side of a mask film 2 where a mask pattern 1 has been formed on the rear surface; a diffusion mask film 5 is formed. The diffusion mask film 5 is placed on a photosenstive etching resist material 8 which has been applied to the surface of a copper foil 7 on an insulating substrate 6. An acrylic sheet 9 is placed on this assembly. When a foreign body 10 exists between the diffusion mask film 5 and the acrylic sheet 9, ultraviolet rays 11 are diffused inside the diffusion film 3 and reach also the part directly under the foreign body 10. As a result, they are not shielded by the foreign body 10 and are incident on the photosensitive etching resist material 8; the material is exposed to them and a pattern can be formed. |
