| 摘要 |
PURPOSE:To prevent the curling of a polyimide film after a metal foil is removed by providing a polyimide layer easy to relieve stress between the metal foil and polyimide having a low coefficient of thermal expansion. CONSTITUTION:A solution of polyamide acid forming polyimide having a glass transition point of 320 deg.C or lower after the completion of imidating reaction is applied to a metal foil as the first layer and a solvent is removed to provide a polyamide acid layer. Subsequently, a solution of polyamide acid wherein the difference between the coefficient of thermal expansion of polyimide after the completion of imidating reaction and that of the metal foil becomes 1.5X10<-5>K<-1> or less is applied to the metal foil as the second layer and a solvent is removed to provide a polyamide acid layer. Thereafter, the imidating reactions of polyamide acids of the first and second layers are completed. That is, a solution containing 3-40wt.% of polyamide acid is emitted to the surface of the metal foil from a slit to be uniformly applied thereto. At this time, the width of the slit is adjusted so that the thickness of polyimide after the removal of a solvent and the completion of imidating reaction becomes 3-15mum to prepare the first layer. Next, the gap between a coater and the metal foil is adjusted so that the thickness of polyimide after the removal of a solvent and the completion of imidating reaction becomes 20-75mum to prepare the second layer. |
