A conductor is at least partially exposed on the surface of a body. A wiring is formed for connection to the conductor. The conductor is made of a Zn—Al alloy. Heat is then applied to the conductor and the wiring. A chemical reaction is accelerated between the conductor and the wiring based on the heat treatment. This allows oxygen to get released out of the conductor and the wiring. Deoxidation is thus realized on the joint surfaces of the conductor and the wiring. Electric resistance is decreased. Electric conduction can thus be established between the conductor and the wiring.