| abstract |
To improve adhesion between a copper core material 1 and a coating layer 2. A bonding wire W having a wire diameter L of 12 μm or more and 50.8 μm or less for connecting an electrode a of an integrated circuit element and a conductor wiring c of a circuit wiring board by a ball bonding method. The outer peripheral surface of the core material 1 made of copper having a purity of 99.99% by mass or more is roughened to Ra: 0.1 to 0.4 μm by bead blouting, shot blasting, acid treatment, strike plating or the like. An oxidation resistant coating layer 2 made of Pd and Pt is formed on the roughened outer surface of the core material. By this roughening, the adhesion area between the outer peripheral surface of the core material and the coating layer 2 is increased, and the adhesion force is improved. For this reason, it is hard to produce the crack of a coating layer by the bending of a wire, and Cu surface is hard to be exposed to the coating layer surface. Such non-exposure means that the thickness of the coating layer can be reduced, and it is difficult to cause the FAB to be cured and is economical. [Selection] Figure 2 |