Degradation behavior of polyimide in perfluorocarbon liquid
Minamitani Rintaro; Hatsuda Toshio; Takahashi Kenji; Kasai Ken'-ichi
Abstract:Perfluorocarbon liquid coolant Fluorinert FC-72 for electronic devices has a high thermal stability and a low chemical reactivity. However, FC-72 has been shown to liquate some organic materials. Polyimide has been used extensively in electronic devices as an insulator and as a protective coating. In the present study, the degradation behavior of polyimide in FC-72 was investigated by measuring chemical and mechanical properties. It was found that polyimide had no change of chemical properties, such as dissolution of the constituent and swelling degree, and mechanical properties, such as tensile strength and peel strength in dry FC-72. At temperatures below 150 degree C, the tensile strength of the polyimide did not degrade by thermal oxidation. The swelling ratio and peel strength degraded as the saturation ratio of dissolved water increased. At temperatures above room temperature, the saturation ratio of dissolved water in FC-72 decreased because of the increasing solubility of water. The absorbed water in polyimide decreased because of the decreasing saturation ratio of dissolved water in FC-72. In this case, the water didn't have much influence on the polyimide degradation. Key Words:Perfluorocarbon, Inert coolant, Polyimide, Degradation, Electronic device