Partial Carbonization of Aromatic Polyimide Films
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K,
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INTRODUCTION Development of silicon in electronic industries has been tremendously growing in the 20th century. It is natural to consider carbon, which is also in the same column in the periodic table as silicon, to be a candidate of an electronic material. In general industrial carbon is made from pitch. Such carbon normally contains a lot of impurities. We have chosen aromatic polyimide as a raw material and partially carbonized and studied electrical properties. EXPERIMENT Kapton films (trade mark of the Du Pont Co.) of 20 Mm were cut into 60mm X 25mm. The films were sandwiched between high purity graphite blocks and bound by a wire. The assembly was put in a fused quartz tube and hydrogen gas or nitrogen gas was flown. After a few minutes, a voltage of I 00V was applied to the heating elements of a split furnace. The temperature was measured by an alumel-chromel thermocouple with a digital-multimeter. After the temperature was reached to a carbonization temperature, the temperature was kept constant for 30 minutes. The heating current was cut and the gas was continuously flown until the furnace temperature became 200 0 C. Silver paste was painted on the film for the electrodes. Copper foils were used for the electrodes contact with silver paste and connected to lead wires. The foil and the electrodes were sandwiched with acrylic resin boards. The assembly was fastened with screws and nuts. The whole assembly was put in a plastic bag and put in a 389 Mat. Res. Soc. Symp. Proc. Vol. 593 ©2000 Materials Research Society
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Fig. 1. Logarithum of electrical conductivity against the inverse of absolute measuring temperature. (a) is for the specimen cabonized in hydrogen atmosphere and (b) is for the specimens carbonized in nitrogen atmosphere. 0.12
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Fig. 2. Activation energies E against the carbonized temperature.
Fig. 3. o-0 vs. carbonized temperature. 390
silicone bath whose temperature was controlled. An alumel-chromel thermocouple was set in the assembly. The four point method was used to avoid the contact voltage and the leak for the voltmeter. All the readi
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