주쇄 구조에 따른 내열성 폴리이미드 박막내에서 사슬의 강직성 정도가 열적 안정성과 잔류 응력에 미치는 영향을 살펴보았다. Poly(p-phenylene pyromellitimide); PMDA-PDA (p-phenylene biphenyltetracarboximide); BPDA-PDA, poly (4,4’-oxydiphenylene pyromellitimide); PMDA-ODA, poly(4-4’-oxydiphenylene biphenyltetracarboximide); BPDA-ODA, poly (4’4-oxydiphenylene benzophenonetetracarboximide); BTDA-ODA를 각각 합성하여 폴리이미드 박막의 열적 성질과 잔류 응력(residual stress)을 온도 25-350℃에서 in-situ로 분석이 이루어졌다. 잔류 응력의 거동은 Wafer Bending Method를 이용한 Thin Film Stress Measurement System(TFSMS)을 제작하여 온도에 따른 연속적인 거동을 측정하였다. 그 결과 사슬의 강직성이 상대적으로 강한 PMDA-PDA의 경우 열적 안정성이 매우 높고, 유리 전이 온도가 400℃ 이상 높게 나왔으며, 잔류 응력은 5 MPa(compression mode)로 가장 낮게 나타났다. 사슬내 가장 유연한 연결고리를 가지는 BTDA-ODA의 잔류 응력은 상온에서 약 41 MPa을 보였으며, 유리 전이 온도는 약 280℃로 나타났다. 또한, 본 연구에서 잔류 응력의 거동으로 유리 전이 온도를 예측할 수 있음을 보였다.

The object is to demonstrate that residual stress behavior in polyimide thin films depends on the degree of chain rigidity of the polyimide backbone structure. The comparison of the residual stress and thermal properties indicates that the residual stress of a polyimide thin film is primarily dependent on the polymer chain rigidity, fully rodlike poly(p-phenylene pyromellitimide);PMDA-PDA semi-rigid poly(p-phenylene biphenyltetracarboximide);BPDA-PDA semi-flexible poly(4,4’-oxy diphenylene pyromellitimide);PMDA-ODA, poly(4-4’-oxydiphenylene biphenyltetracarboximide); BPDA-ODA and flexible poly (4’4-oxydiphenylene benzophenonetetracarboximide); BTDA-ODA were prepared. Residual stress was measured by Thin Film Stress Measurement System(TFSMS) using wafer bending method. As a result, the higher polymer chain rigidity of polyimide thin films shows the lower residual stress in tension on the Si wafer substrate. among the polyimide thin films studied here, rodlike PMDA-PDA shows excellent thermal stability, the highest glass transition temperature, and the lowest residual stress, 5MPa(compression mode), but flexible BTDA-ODA exhibited the highest overall residual stress, 41 MPa with low glass transition temperature, 280℃. In addition, the T_g’s of the polyimides are estimated from the overall residual stress-temperature profile.

Chain Rigidity Backbone Structure Thermal Stability Residual Stress Imidization

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