On the thickness and spatial distribution of a fluoropolymer film deposited by solution dipping

✍ Scribed by H. G. Tompkins; S. P. Sharma

• Publisher: John Wiley and Sons
• Year: 1980
• Tongue: English
• Weight: 568 KB
• Volume: 25
• Category: Article
• ISSN: 0021-8995
• DOI: 10.1002/app.1980.070250207

✦ Synopsis

Abstract

Poly‐1H,1H‐pentadecafuorooctyl methacrylate is a barrier compound used to prevent silicone oil from creeping to relay contacts. It is essentially a methyl methacrylate polymer with a fluorocarbon side chain substituted for one of the methyl hydrogens. It is applied by dipping the part into a solution, with Freon TF as the solvent and the fluorocarbon polymer as the solute. This work considers the spatial distribution of the resulting film of barrier compound when it is deposited in this manner. The specific variables considered are concentration and withdrawal velocity. The samples were withdrawn from the solution with velocity perpendicular to the surface, and we show that the macrosopic uniformity and thickness of the film is dependent on this velocity. There exists a critical velocity (dependent on concentration) above which the film is nonuniform and below which the film is macroscopically uniform. Below the critical velocity, the thickness varies with velocity with approximately a v^2/3^ dependence. The critical velocity is about 13 mm/sec for a concentration of 0.2%. For macroscopically uniform films, a microscopic nonunitormity exists with a coverage of about 1/4 for an average film thickness of 90 Å.