Abstract: A photosensitive resin composition suitable for forming a thick film and an ultra-thick film used for forming a thick resist pattern used in the process of forming a magnetic pole on a magnetic head and a bump, which comprises (A) an alkali soluble novolak resin, (B) an alkali soluble acrylic resin, (C) an acetal compound, and (D) an acid generator.

Abstract: [Object] To provide a chemically amplified photosensitive resin composition suitable for forming a thick film and a super thick film, which has high sensitivity, high film residual properties, good coating properties, high resolution and a good pattern shape, and which gives a pattern excellent in heat resistance, in a photosensitive resin composition requiring the formation of a thick resist pattern film such as in the formation of a magnetic pole of a magnetic head or of a bump. [Solving means] A chemically amplified photosensitive resin composition including an alkali soluble novolak resin (A), a resin or compound (B) which in itself is insoluble or slightly soluble in alkali, but becomes soluble in alkali by the action of an acid, that is acid generating agent (C), and a photosensitizing agent (D) containing a quinonediazide group, as well as, if necessary, an alkali soluble acrylic resin (E) and a crosslinking agent (F) for improving film quality.

Abstract: A photosensitive resin composition suitable for forming a thick film and an ultra-thick film used for forming a thick resist pattern used in the process of forming a magnetic pole on a magnetic head and a bump, which comprises (A) an alkali soluble novolak resin, (B) an alkali soluble acrylic resin, (C) an acetal compound, and (D) an acid generator. A polycondensate comprising a structural unit represented by the following general formula (I) (wherein R represents a saturated alkyl group having 1 to 20 carbon atoms, n is an integer of 1 to 10) as an acetal compound.