| 摘要 |
PROBLEM TO BE SOLVED: To provide a porous film which exhibits homogeneous moisture- permeability and waferproofness because of its small variation in micropore size and which is low in cost. SOLUTION: A photosensitive permanent resist is applied in a thickness of about 10μm to a substrate (e.g. an aluminum foil) 10 with a bar coater and is baked under specified conditions to form a resist film 20. The resist film is closely covered with a photomask 30 having microporous pattern formed through it, is exposed to light, and is developed with a developing soln. exclusively used therefor. After the developed resist film is baked, it is peeled from the substrate or the substrate is dissolved and removed, giving a porous film 21 having many micropores 21a formed through it. Thus obtd. porous film has uniform-sized micropores, has homogeneous moisture permeability and waterproofness, and can be produced at a low cost since the production process is simple and the cost of production equipment is low.
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