| 摘要 |
PROBLEM TO BE SOLVED: To surely stick conductor foil, such as the copper foil, etc., and a film-like insulating layer to each other in one body by thermal fusion in a flexible printed wiring board using a thermoplastic insulating layer so that the foil may have a soldering heat resistance. SOLUTION: A flexible printed wiring board is provided with a film-like insulator which contains a styrene-based resin composition having a syndiotactic structure and a thermoplastic resin which is compatible with the resin composition as main ingredients. The content of the styrenebased resin composition is adjusted to >=35 wt.% and the thermoplastic resin has a peak crystal melting point of >=260 deg.C when the melting point is measured after the temperature of the resin is raised for differential scanning colorimetry and meets an inequality, [(ΔHm-ΔHc)/ΔHm]<=0.6, expressing the relation between the quantity of crystal melting heatΔHm and the quantity of crystallizing heatΔHc which occurs due to the crystallization during a temperature rise. In addition, conductor foil is melt-stuck to one or both surfaces of the film-like insulator and a conductive circuit is formed of the conductor foil.
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