Abstract: Provided are an expandable or bendable circuit board having good body-contact feel, strong against bending and folding, and an electronic device made therefrom. The bendable circuit board includes: a film comprising a polyurethane synthesized by reacting a long-chain polyol with polyisocyanate and having a storage modulus at 25° C. of 20 to 200 MPa, a tensile strength of 20 to 80 MPa, and an elongation at break of 500 to 900%, and the temperature of which the storage elastic modulus reaches to 1 MPa is at 155° C. or higher; and circuit wiring formed in contact with a surface of the film. Alternatively, an expandable circuit board having the ratio ?/?0 of the specific electrical resistance ? of the circuit wiring when the circuit wiring is expanded to the specific electrical resistance (?·cm) ?0 of the circuit wiring before the circuit wiring is expanded is within a range of 1.05 to 10.0.

Abstract: Provided are an expandable or bendable circuit board having good body-contact feel, strong against bending and folding, and an electronic device made therefrom. The bendable circuit board includes: a film comprising a polyurethane synthesized by reacting a long-chain polyol with polyisocyanate and having a storage modulus at 25° C. of 20 to 200 MPa, a tensile strength of 20 to 80 MPa, and an elongation at break of 500 to 900%, and the temperature of which the storage elastic modulus reaches to 1 MPa is at 155° C. or higher; and circuit wiring formed in contact with a surface of the film. Alternatively, an expandable circuit board having the ratio ?/?0 of the specific electrical resistance ? of the circuit wiring when the circuit wiring is expanded to the specific electrical resistance (?·cm) ?0 of the circuit wiring before the circuit wiring is expanded is within a range of 1.05 to 10.0.