AVS 45th International Symposium
    Vacuum Technology Division Wednesday Sessions
       Session VT-WeA

Paper VT-WeA5
Thermal Stability and Sealing Performance of Perfluoroelastomer Seals as a Function of Crosslinking Chemistry

Wednesday, November 4, 1998, 3:20 pm, Room 329

Session: Vacuum Systems and Components
Presenter: M.J. Heller, DuPont Dow Elastomers
Authors: M.J. Heller, DuPont Dow Elastomers
J.M. Legare, DuPont Dow Elastomers
S. Wang, DuPont Dow Elastomers
S. Fukuhara, DuPont Dow Elastomers
Correspondent: email address not available
Perfluoroelastomer (e.g. Kalrez, Chemraz, etc.), fluoroelastomer (e.g. Viton, etc.) and silicone parts are widely used in sealing applications for semiconductor wafer processing equipment. More specifically, they are often used as O-ring seals in dry chemical process equipment (e.g., Plasma Etchers, Ashers, Diffusion Furnaces, CVD, LPCVD, RTP and Lamp Anneal, etc.). Many of these seals are required to function at process temperatures ranging from 200 - 300°C and in some cases higher. The ability of an elastomer to resist thermal degradation has a significant impact on its ability to function effectively as a seal over time. This paper evaluates and compares the relative long term sealing performance of perfluoroelastomers having different crosslinking chemistries and other typically specified high performance elastomers. Long term compression set and seal force retention data is presented, including a discussion of the different test methods and their relative value in predicting seal performance at elevated temperatures. In addition, air heat aging data for other typically measured physical properties (i.e., Shore A Hardness, 100% Modulus, Tensile Strength at Break, Elongation at Break, % Weight Loss) is also presented and discussed. Results indicate perfluoroelastomers seals have the best long-term compression set characteristics and retain the highest percentage of their original sealing force over time. In addition, data shows perfluoroelastomers having an organo-metallic cross-linking system are the most thermally stable and exhibit the best long term seal performance at elevated temperatures versus those having an organic-peroxide cross-linking system. Finally, because the test conditions best reflect static o-ring seal service conditions, analysis of seal force retention test results provide a more realistic comparison of thermal stability and its relative impact on sealing performance.