| abstract |
The flexible printed substrate comprises an insulating resin layer comprising a low-linear expansion polyimide resin layer (2) and a thermoplastic polyimide resin layer (3), and a metal layer (1) or a wiring circuit formed on the low-linear expansion polyimide resin layer (2) of the insulating resin layer, wherein a mixed region of the polyimide resin components is formed in the interface between the low-linear expansion polyimide resin layer (2) and the thermoplastic polyimide resin layer (3). A flexible printed substrate imparted with an adhesive property for loading on an external substrate, a double printed substrate having formed on both surfaces thereof a metal layer or a wiring circuit, and a multilayer substrate having a multilayer structure are disclosed. |