The adhesion mechanism between polyimides and aromatic thermosetting copolyester (ATSP) involved in the solid-state bonding technique using submicrometer ATSP coatings was evaluated. The adhesion strength at the interface between ATSP and polyimide is strongly related to the diffusion of ATSP into the polyimide base layer. We used dynamic secondary ion mass spectrometry to study the interface width between deuterated ATSP and polyimides and found that the interface between ATSP and poly(4,4'-diphenylether pyromellitimide) (PMDA-ODA) is wider than the interface between ATSP and poly(p-phenylene biphenyltetracarboximide) (BPDA-PPD) because of the less rigid chain in the PMDA-ODA. By partially curing both polyimides, the interface width was greatly increased, which could lead to an improved adhesion at the interface between polyimide BPDA-PPD and ATSP. (C) 2004 Wiley Periodicals, Inc.