A polyimide resin comprising a phenolic hydroxyl group and/or a carboxyl group has good reactivity, so that has been attracts much interest. For example, Japanese Patent Application Laid-Open No. 6-200216 and Japanese Patent No. 3329677 describe a polyimide silicone comprising a phenolic hydroxyl group.
It is described that the polyimide silicone has good heat resistance, chemical resistance, and electrical insulating property to be used for applications such as protective or electrical insulating layer and cover-lay film for semiconductor devices, multilayer printed wiring board and soldered parts.
The aforesaid properties such as heat resistance can be improved by increasing an amount of the phenolic hydroxyl group and/or carboxyl group. However, such a polyimide silicone resin will shrink more when cured and lose flexibility, causing warpage of a substrate encapsulated with the polyimide silicone resin.