Fine pitch wire bonding has traditionally been the domain of gold wires. The significant increase in gold commodity prices has driven a continuous reduction in wire diameters to minimize the impact of the raw materials cost of the wire. This has reached a point now where copper wires are beginning to displace gold wires despite the technical challenges associated with copper wires. The basic challenges like propensity for oxidation, hardness and propensity for corrosion can be managed with the appropriate investment in tooling and infrastructure. Doubts are persisting about yield and reliability. With a very methodical approach to developing the process controls, it can be demonstrated that yields are as good as those for gold despite the fact that copper bonds are not reworkable. Likewise, the typical JEDEC reliability tests can be full filled. Here, an extensive effort has been placed on extended JEDEC testing to demonstrate that with good process control and proper materials choices, test durations of more than 2x can be passed. This excellent performance demonstrates that copper wire bonding can be as good as or better than gold wire bonding.

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