Photosensitive element, resist pattern formation method and printed wiring board production method

A photosensitive element at least comprising:

• a support;
• and
• a photosensitive resin composition layer provided on said support and composed of a photosensitive resin composition containing (A) a binder polymer which contains 3 to 30% by weight, relative to all copolymerizable components, of styrene or a styrene derivative as a copolymerizable component, (B) a photopolymerizable compound having one or more polymerizable ethylenic unsaturated bonds in a molecule thereof, and (C) a photopolymerization initiator;
• wherein,
• the photosensitive resin composition contains a thioxanthone-based compound represented by the following chemical formula (I) as the component (C):
• [Chemical Formula I]
• (in formula (I), R1, R2, R3, R4, R5, R6, R7 and R8 respectively and independently represent a hydrogen atom, halogen atom or hydrocarbon group), and also contains as the (C) photopolymerization initiator an acylphosphine oxide compound represented by the following chemical formula (II):
• [Chemical Formula II]
• (in formula (II), X, R11 and R12 respectively and independently represent a monovalent organic group, and h and i respectively and independently represent an integer of 0 to 5 and
• when the parts by weight of the thioxanthone-based compound relative to 100 parts by weight for the total weight of the component (A) and the component (B) is taken to be P, and the film thickness of the photosensitive resin composition layer is taken to be Q (μm), then R, which is the product of P and Q, satisfies the condition of the following formula (1)
• 25.5≦R≦79.0 (1),
• the photosensitive element having a property of photosensitivity to light at a wavelength in a range of 400 to 415 nm.