Aromatic polyamide porous film, method for producing aromatic polyamide porous film, and secondary battery

摘要

An object of the present invention is to provide an aromatic polyamide porous film that is excellent in thinning and can easily exhibit a stable porous property even when used at a high temperature for a long period of time. A porous film having a cross-sectional area S (10) μm2 cut at a depth of 10 nm from the surface layer and a depth of 20 nm from the surface layer when measuring the range of Sμm2 using an atomic force microscope on at least one surface The cross-sectional area S (20) μm2 cut by the step can be achieved by forming an aromatic polyamide porous film characterized by satisfying the following formula at the same time. 0.01 ≦ S (10) /S≦0.35≦S (20) / S (10) ≦ 20