Taiyo Holdings Co., Ltd.

Takahiro Yoshida

Masao Arima

Shouji Minegishi

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.

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Hiki-gun, Japan

Takahiro Yoshida