| 摘要 |
<p>PROBLEM TO BE SOLVED: To provide a flexible printed board which has a polyimide layer, having high adhesive strength with respect to metal foil and will not curl before and after etching the metal foil. SOLUTION: In this flexible printed board provided with the polyimide layer formed by imidizing a polyamic acid varnish film formed on the metal foil, the polyimide layer has a range of coefficient of linear expansion of 10×10-6 (1/K) to 30×10-6 (1/K) and shows a softening point, at least the imidizing temperature.</p> |
