Abstract
Wire bonding is used as a method of the electrical connections between an electrode terminal on a chip of a semiconductor and an outer lead terminal. Cu wire has a good corrosion resistance and high electrical and thermal conductivity. Furthermore, Cu wire can be bonded directly to Cu alloy lead frame as a 2nd stitch bonding. For these reasons, a practical application of the Cu wire bonding process is anticipated. But, for application of Cu wire stitch bonding onto Cu alloy lead frame, there are a lot of difficult problems to be solved.In this report, the influence of the bonding conditions and surface states on the bondability of Cu wire stitch bonding is investigated. It is pointed out that the control of the wire deformation behavior is necessary for obtaining the good bondability in thermosonic Cu wire bonding. Furthermore, it is clarified that the surface state on Cu alloy lead affects on the bondability. If the maximum surface roughness on Cu alloy lead is more than 0.4 μm, or if the thickness of the oxide film on Cu alloy lead is more than 10 nm, the bondability of Cu wire stitch bonding is inferior.
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