Modeling of the vacuum drying process for color resistor thin film
Date Issued
2006
Date
2006
Author(s)
Lin, Da-Wei
DOI
zh-TW
Abstract
The film coating processing is the common technology in modern precision industry，and the controlling of the film thickness is an important issue. This thesis focuses on the simulation of the vacuum drying process in the color resistor coating applied in the color filter manufacturing. The driving force of this process is the vacuum pumping. By decreasing the concentration of solvent in gaseous phase，the solvent evaporation rate will increase. We built the mathematical model of the mass transfer at the interface of the thin film and in the vacuum chamber. By the mathematical simulation， we can analyze the film thickness changing with pumping time.
In the first part，we study the working principle of the vacuum pump and the pressure dropping curve. We try to link it to the output term in the mass balance equation. In the second part，we built up the mass transfer model based on the mass balance concept. For the evaporation flux at the interface，we introduce two kind of expressions，one is the two film theory，the other is the model of gaseous diffusion governing mode. We also consider the evaporation cooling effect. In the third part, we simulated this process based on the model above，and the mathematical model is a system of ODES. Compare with the actual process data from the factory，we find the model of gaseous diffusion governing mode is closer to the actual process，and the evaporation cooling effect is not so evident. But from the simulation result，the pumping speed play an important role in this process，if we increase the pumping speed to 1.5 times，we can reduce the process time from 46s to 20s，and that can improve the throughput of the color filter factory.
Subjects
真空乾燥
彩色濾光片
數值模擬
vacuum drying
color filter
numerical modeling
Type
thesis
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