Bonding wire for semiconductor devices

A bonding wire for semiconductor devices, the bonding wire comprising:

• a core material of Cu or Cu alloy;
• and
• a coating layer containing a conductive metal other than Cu formed on a surface of the core material, wherein
• in a concentration profile in a depth direction of the wire obtained by performing measurement using Auger electron spectroscopy (AES), an average value of sum of a Pd concentration CPd (atomic %) and an Ni concentration CNi (atomic %), CPd+CNi, for measurement points in the coating layer is 50 atomic % or more, an average value of a ratio of CPd to CNi, CPd/CNi, for measurement points in the coating layer is 0.2 or more and 20 or less and a thickness dt of the coating layer is 20 nm or more and 180 nm or less,
• an Au concentration CAu at a surface of the wire is 10 atomic % or more and 85 atomic % or less, and
• an average size of crystal grains in a circumferential direction of the wire is 35 nm or more and 200 nm or less when the surface of the wire is analyzed by using an Electron Backscattered Diffraction (EBSD) method.