| abstract |
The present invention provides a printed circuit board that suppresses the softening phenomenon of circuit wiring due to heat and aging, enhances durability, improves brittleness, and suppresses generation of cracks. A printed circuit board having a circuit wiring 2 made of a metal film on an insulating layer 1 of the substrate, wherein the circuit wiring 2 is made of a laminate of three or more layers of a copper-based metal film, The copper-based metal film constituting the lowermost layer 2a and the uppermost layer 2c has a tensile strength at room temperature of 100 to 400 MPa, and a copper-based layer constituting the layer (intermediate layer 2b) interposed between the lowermost layer 2a and the uppermost layer 2c The tensile strength at normal temperature in the metal film is 700 to 1500 MPa. [Selection] Figure 1 |