Circuit board and assembly thereof

The circuit board is provided with an insulating film including thin films and insulating functions in the interface between the need to secure the conductor insulation is disclosed. Insulating thin film may be formed respectively from a material containing the material, the functional film is a titanium nitride containing ferrule Lin. Then, the insulating film may be provided in the core portion and the surface of the metal material, the core portion, are provided on the other surface side of the recess portion in the incoming direction can be inserted into the electronic device, such as an integrated circuit.