| 摘要 |
PROBLEM TO BE SOLVED: To provide a polyimide film suffering from small dimensional changes both at ordinary temperature and at a higher temperature and suitable for a fine pitch circuit board. SOLUTION: The polyimide film has a Young's modulus of at least 4 GPa, a heat shrinkage ratio at 350°C of at most 0.15% and a heat shrinkage ratio at 400°C of at most 0.20%, and preferably has a water absorption of at most 2.5% and a thermal expansion coefficient between 350-400°C of 20-30 ppm/°C. The film is excellent in processability, has high dimensional stability and can reduce dimensional changes in a step at a higher temperature, and therefore is suitably employed for the fine pitch circuit board. COPYRIGHT: (C)2004,JPO |
