Copper alloy bonding wire for semiconductor devices

A copper alloy bonding wire for semiconductor devices, consisting of:

• one or more kinds of first elements selected from Ga, In, and Ir, wherein the total content of the first elements is 0.05% by mass or more and 3% by mass or less;
• and
• 0.0005% by mass or more and 0.5% by mass or less of at least one or more kinds of third elements selected from Ag and Au, with respect to the entire wire, with the balance consisting of Cu and inevitable impurities,
• wherein a total content of the first elements and the third elements is more than 0.1% by mass,
• wherein the copper alloy bonding wire does not have a coating layer based on a metal other than copper, and
• wherein an average crystal grain size (μm) in core cross section in a direction perpendicular to a wire axis of the copper alloy bonding wire is
• 0.02×R+0.4 or more (1a)
• 0.1×R+0.5 or less (1b)
• where R (μm) is a diameter of the wire.