Authors: T. Ebina, K. Kawasaki, T. Nakamura, M. Yoshida, H. Hayashi, T. Yamashita, T. Yamamoto, D. Misyou, S. Bando, N. Hayashizaka, Y. Umeda
Affilation: National Institute of Advanced Industrial Science and Technology, Japan
Pages: 706 - 709
Keywords: clay, polyimide
A new clay polymer composite film was prepared by mixing specially processed non-swelling clay and polyimide at an optimal ratio. The newly developed film (80 µm thick) was heat-resistant at 450°C and showed very little shrinkage (0.04%) after heating from room temperature to 350°C. These characteristics enable production of very fine electronic circuits on the film with such methods as printing. Additionally, the newly developed film has a low linear thermal expansion coefficient (the ratio of change in length to increase in temperature) of approximately 10 ppm/°C, the VTM-0 flammability on UL-94 rating, about the same electrical insulation as polyimide, even lower moisture absorbency than polyimide, and other characteristics. This film material has a water vapor barrier property sufficient for use as the back sheet of crystal silicon solar cells, we also succeeded in aligning the clay crystals parallel to the film surface and further improving the water vapor barrier property. This film was produced by casting a raw material paste, then drying the solvent and subsequently heating the material. Trials carry on repeatedly establishing production methods and conditions for rolls of the film up to 50 cm wide with thicknesses from 30–120 µm.