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In‐plane solvent diffusion in a photosensitive polyimide
Author(s) -
Shih DaYuan,
Nunes Sharon,
Paraszczak Jurij,
Galligan Eileen,
Cataldo John,
Serino Russell
Publication year - 1992
Publication title -
journal of applied polymer science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.575
H-Index - 166
eISSN - 1097-4628
pISSN - 0021-8995
DOI - 10.1002/app.1992.070460717
Subject(s) - polyimide , activation energy , arrhenius equation , diffusion , solvent , polymer chemistry , materials science , analytical chemistry (journal) , benzophenone , chemistry , thermodynamics , composite material , physics , organic chemistry , layer (electronics)
The diffusion of an organic solvent, N ‐methylpyrollidinone (NMP), in a fully imidized photosensitive polyimide, 4,4′‐benzophenone tetracarboxylic dianhydride (BTDA– t MDA), was investigated. The polyimide (PI) films were prepared by spin‐coating, soft‐bake, deep UV exposure, and final‐baked to a peak temperature ranging from 230 to 375°C. The thickness of the final films is approximately 5.0 μm. Patterned metal was then electronbeam‐evaporated through a molybdenum shadow mask over the PI surface. The rate of lateral (in‐plane) diffusion of NMP in the PI covered with metal follows Fick's \documentclass{article}\pagestyle{empty}\begin{document}$ \sqrt t $\end{document} relationship over a temperature range of 40–85°C. The rate of diffusion was shown to increase with increasing NMP temperatures, typical of a thermal‐activated process. The diffusion coefficients, as measured by the solvent penetration distance as a function of the square root of time, were found to obey the Arrhenius equation: D = D 0 × exp(− Q / RT ) cm 2 /s, where the frequency factor, D 0 , ranges from 0.0015 to 0.0045 cm 2 /s, and the activation energy, Q , ranges from 5.52–6.34 kcal/mol. Both D 0 and Q decrease with increasing PI baking temperatures. © 1992 John Wiley & Sons, Inc.