Abstract: Disclosed is a blend capable of forming a semi-interpenetrating network when cured of (A) a solution of about 30 to about 50 wt % solids in an organic solvent of a fully imidized polyimidesiloxane and (B) about 5 to about 30 pbw per 100 pbw of the polyimidesiloxane of an epoxy resin which comprises a cycloaliphatic epoxy and an epoxy curing agent. The polyimidesiloxane is the reaction product of an aromatic dianhydride and diamine. The diamine is about 5 to about 80 mole % non-siloxane containing aromatic diamine and the remainder a siloxane diamine, where the siloxane diamine is about 40 to about 80 wt % of the weight of the polyimidesiloxane. The blend is used to bond metal parts to ceramic packages.

Abstract: Disclosed is method of making a polyimidesiloxane extended block copolymer containing at least one polyimide block made by reacting a dianhydride with a diamine that does not contain a siloxane group, and at least one polyimidesiloxane block made by reacting a dianhydride with a diamine that contains at least one siloxane group, where each polyimidesiloxane block is prepared using more than one mole of the dianhydride for each mole of the siloxane-containing diamine. That is, any siloxane-imide blocks in the polyimidesiloxane are formed from amic acid blocks terminated in anhydride groups and any imide blocks in the polyimidesiloxane are formed from amic acid blocks terminated in amine groups. The polyimidesiloxane block copolymers have higher glass transition temperatures than the corresponding non-extended block copolymers while retaining the same solubility.