Manufacturing method of hardened film, printed wiring board and electronic device

Abstract

This invention provides a method for manufacturing a hardened film, which involves light irradiation and heat curing to produce a hardened film with a relatively thick film and a high glass transition temperature (Tg), while simultaneously suppressing surface cracking. This invention is a method for manufacturing a hardened film with a glass transition temperature (Tg) of 120°C or higher and a film thickness of 50 μm or higher, comprising the following steps: repeatedly applying a curing composition comprising a compound having a (meth)acrylic group and a compound having an epoxy group, and irradiating the aforementioned applied curing composition with light to form a pre-cured film with an elongation at break of 7% or higher and 200% or lower; and then heat curing the aforementioned pre-cured film.

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