COVERLAY FILM, PRINTED WIRING BOARD TO BE EQUIPPED WITH LIGHT-EMITTING ELEMENT, AND LIGHT SOURCE DEVICE

摘要

Provided are: a coverlay film which is particularly applicable to a printed wiring board on which an LED is to be mounted; and so on. This coverlay film exhibits a high reflectivity in a visible light region, suffers from little lowering in reflectivity even under an environment with high-temperature heat load and under an environment for testing light resistance, and can accommodate large-area printed wiring boards. A coverlay film which is to be used for the protection of a conductor circuit of a printed wiring board and which is provided with a resin layer that contains both a polyorganosiloxane and an inorganic filler, wherein the average reflectivity of the coverlay film in a wavelength region of 400 to 800nm is 85% or higher and the lowering thereof in the reflectivity at a wavelength of 450nm is 5% or less as determined after the heat treatment at 260°C for 10 minutes.