There is provided a Cu bonding wire having a Pd coating layer on a surface thereof, that improves bonding reliability of a ball bonded part in a high-temperature and high-humidity environment and is suitable for on-vehicle devices.

The bonding wire for a semiconductor device includes a Cu alloy core material and a Pd coating layer formed on a surface of the Cu alloy core material, and the bonding wire contains In of 0.011 to 1.2% by mass and has the Pd coating layer of a thickness of 0.015 to 0.150 μm. With this configuration, it is able to increase the bonding longevity of a ball bonded part in a high-temperature and high-humidity environment, and thus to improve the bonding reliability. When the Cu alloy core material contains one or more elements of Pt, Pd, Rh and Ni in an amount, for each element, of 0.05 to 1.2% by mass, it is able to increase the reliability of a ball bonded part in a high-temperature environment of 175° C. or more. When an Au skin layer is further formed on a surface of the Pd coating layer, wedge bondability improves.

The present invention provides a ball forming method for forming a ball portion at a tip of a bonding wire which includes a core material mainly composed of Cu, and a coating layer mainly composed of Pd and formed over a surface of the core material, wherein the ball portion is formed in non-oxidizing atmosphere gas including hydrocarbon which is gas at room temperature and atmospheric pressure, the method being capable of improving Pd coverage on a ball surface in forming a ball at a tip of the Pd-coated Cu bonding wire.

There is provided a Cu bonding wire having a Pd coating layer on a surface thereof, that improves bonding reliability of a ball bonded part in a high-temperature and high-humidity environment and is suitable for on-vehicle devices. The bonding wire for a semiconductor device includes a Cu alloy core material and a Pd coating layer formed on a surface of the Cu alloy core material, and the bonding wire contains In of 0.011 to 1.2% by mass and has the Pd coating layer of a thickness of 0.015 to 0.150 m. With this configuration, it is able to increase the bonding longevity of a ball bonded part in a high-temperature and high-humidity environment, and thus to improve the bonding reliability. When the Cu alloy core material contains one or more elements of Pt, Pd, Rh and Ni in an amount, for each element, of 0.05 to 1.2% by mass, it is able to increase the reliability of a ball bonded part in a high-temperature environment of 175 C. or more. When an Au skin layer is further formed on a surface of the Pd coating layer, wedge bondability improves.

To provide a wire bonding method and a wire bonding device capable of stably forming a free air ball having a large ball diameter while suppressing oxidation of the free air ball, in addition to supply of an oxidation prevention gas from gas supply means (10) into an insertion portion (32), an oxidation prevention gas is supplied from a gas supply nozzle (40), which is arranged outside the insertion portion (32), so as to cover an inlet of the insertion portion (32). Under a state in which a leading end of a wire (74) is positioned inside the insertion portion (32), and in which a leading end of a capillary (3) is positioned outside the insertion portion (32), spark discharge is generated. With this, a free air ball (75) having a large ball diameter can be formed while suppressing oxidation of the free air ball (75) and stabilizing the free air ball (75).

The present invention provides a ball forming method for forming a ball portion at a tip of a bonding wire which includes a core material mainly composed of Cu, and a coating layer mainly composed of Pd and formed over a surface of the core material, wherein the ball portion is formed in non-oxidizing atmosphere gas including hydrocarbon which is gas at room temperature and atmospheric pressure, the method being capable of improving Pd coverage on a ball surface in forming a ball at a tip of the Pd-coated Cu bonding wire.

To provide a wire bonding method and a wire bonding device capable of stably forming a free air ball having a large ball diameter while suppressing oxidation of the free air ball, in addition to supply of an oxidation prevention gas from gas supply means (10) into an insertion portion (32), an oxidation prevention gas is supplied from a gas supply nozzle (40), which is arranged outside the insertion portion (32), so as to cover an inlet of the insertion portion (32). Under a state in which a leading end of a wire (74) is positioned inside the insertion portion (32), and in which a leading end of a capillary (3) is positioned outside the insertion portion (32), spark discharge is generated. With this, a free air ball (75) having a large ball diameter can be formed while suppressing oxidation of the free air ball (75) and stabilizing the free air ball (75).