Taiyo Holdings Co., Ltd.

Nippon Shokubai Co., Ltd.

Shouji Minegishi

Masao Arima

Takahiro Yoshida

Nobuaki Otsuki

Manabu Akiyama

In a layered structure having at least a substrate and a photosensitive resin layer or cured film layer formed on the substrate and containing an inorganic filler, the content of the inorganic filler in the photosensitive resin layer or cured film layer is low on the side contacting the substrate and high on the surface side away from the substrate, so that a linear thermal expansion coefficient of the photosensitive resin layer or cured film layer as a whole is maintained as low as possible. Preferably, the inorganic filler content in the layer gradually increases continuously obliquely or stepwise from the side contacting the substrate to the surface side away from the substrate. A photosensitive dry film containing the above-mentioned photosensitive resin layer is suitable for use as a solder resist or an interlayer resin insulation layer of a printed wiring board.

Layered structure and photosensitive dry film to be used therefor

A solder resist having both adequate sensitivity at photo-irradiation and alkali developability, and the solder resist forming a cured product which is excellent in dimensional stability against temperature change, does not exhibit brittleness, and further, is excellent in water resistance, electrical insulation, thermal cycle test resistance (TCT resistance) and the like is provided, and further, a dry film having a solder resist layer, a cured product and a printed wiring board are provided. The solder resist comprising an acid-modified vinyl ester synthesized from an epoxy compound, a phenol compound, an unsaturated monobasic acid and a polybasic acid anhydride, wherein the epoxy compound contains a crystalline epoxy resin having a melting point of 90&#xb0; C. or more, and the phenol compound contains a compound having a bisphenol S structure.

Growing community of inventors

Hiki-gun, Japan

Shouji Minegishi