RELEASE FILM AND FLEXIBLE PRINTED CIRCUIT BOARD

摘要

PROBLEM TO BE SOLVED: To provide a release film having such a property that peeling strength of a used release film subjected to a high temperature during a lamination process is decreased to a level substantially equal to the peeling strength of a new release film.SOLUTION: A release film is made reusable by annealing a used polybutylene terephthalate resin release film used for hot-press adhesion between a film substrate of a flexible printed circuit board and a coverlay film in such a manner that in an observation of crystallization by differential scanning calorimetry while elevating temperature, the film shows an endothermic temperature of 185°C or higher and lower than the melting point of the resin.