| 摘要 |
PROBLEM TO BE SOLVED: To provide a flexible printed board which can be used for a minute circuit, excellent in dimensional stability suppressing curl as much as possible, by obtaining polyimide with an appropriate coefficient of linear thermal expansion. SOLUTION: In the flexible substratE, polyimide resin layers more tHan one layer are formed on a conductor. A polyamic acid component shown in formula 1, where A is a structure of the figure, X is a tetravalent organic group, and n is an integer, and a polyimide precursor, in which an acid anhydride component and an isocyanate component are reacted, shown in formula 2, where W is a tetravalent organic group, Y is a diatomic organic groups, and m is an integer, are changed into imide so that the polyimide resin layer is formed.
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