ISSN:
0032-3888
Keywords:
Chemistry
;
Chemical Engineering
Source:
Wiley InterScience Backfile Collection 1832-2000
Topics:
Chemistry and Pharmacology
,
Mechanical Engineering, Materials Science, Production Engineering, Mining and Metallurgy, Traffic Engineering, Precision Mechanics
,
Physics
Notes:
The effect of solvent evaporation on spun-on polymer thickness is investigated. Film thickness is shown to be proportional to spin speed raised to the negative of a constant, b. This constant is specifically considered. Of particular interest is the short initial period during spin coating signified by a rapid increase in solution viscosity, but where solvent diffusion in solution is not yet significant. Many previous theories have suggested the existence of a single value for b dependent only upon environment and spin coating system. Here, a single polymer dissolved in five pure solvents is examined. The polymer is Thermid IP-600 (National Starch and Chemical Co.), an isoimide precursor. The solvents considered are n-methyl-2-pyrrolidinone, dimethyl sulfoxide, dimethyl formamide, ethylene glycol dimethyl ether, and 2-methoxyethyl ether. Spin Speed ranges from 0.6 to 7.0 kRPM and spin time is held at 15 s. It is shown that b varies from 0.97 for n-methyl-2-pyrrolidinone to 0.57 for 2-tncthoxycthyl ether. An empirical relation describing the behavior of b for this particular polymer and spin conditions used is b = [(MW)s(Pvap)s]/[(MW)n(Pvap)n]-0.1, where (MW)s and (MW)n are the molecular weights of the solvent and of n-butyl acetate, respectively and where (PVaP)s and (Pvap)n are the vapor pressure of the pure solvent and the vapor pressure of n-butyl acetate, respectively.
Additional Material:
2 Ill.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1002/pen.760300309
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