Analysis by Oxygen Atom Number Density Measurement of High-speed Hydrophilic Treatment of Polyimide using Atmospheric Pressure Microwave Plasma

摘要

This paper describes the fundamental experimental data of the plasma surface modification of the polyimide using atmospheric pressure microwave plasma source. The experimental results were discussed from the point of view of the radical's behavior, which significantly affects the modification mechanism. The purpose of the study is to examine how the value of the oxygen atom density will affect the hydrophilic treatment in the upstream region of the plasma where gas temperature is very high. The surface modification experiments were performed by setting the polyimide film sample in the downstream region of the plasma. The degree of the modification was measured by a water contact angle measurement. The water contact angle decreased less than 30 degrees within 1 second treatment time in the upstream region. Very high speed modification was observed. The reason of this high speed modification seems that the high density radical which contributes the surface modification exist in the upstream region of the plasma. This tendency is supposed to the measured relatively high electron density (～10~(15)cm~(-3)) at the center of the plasma. We used the electric heating catalytic probe method for oxygen radical measurement. An absolute value of oxygen radical density was determined by catalytic probe measurement and the results show that ～10~(15)cm~(-3) of the oxygen radical density in the upstream region and decreases toward downstream region. The experimental results of the relation of the oxygen radical density and hydrophilic modification of polyimide was discussed.