Microstructure evolution of melt-extracted copper alloy wires.

A new casting method for processing copper alloy bonding wires was proposed. The microstructure evolution process of melt-extracted copper alloy wires was analyzed. The causes of the formation of non-uniform microstructures were analyzed. [Display omitted] Copper alloy wires are regarded as essential for bonding in semiconductor packaging. However, the existing single-crystal copper wires are susceptible to oxidize, resulting in connection failure. And the current production process of multi-pass cold-drawing is complicated. In this study, nickel-aluminum-bronze (NAB) alloy wires by the melt-extracted method were investigated to avoid the problems mentioned above. The results showed that the microstructure of the copper alloy wire differs depending on the region. The nano-Ni 3 Al phase precipitates on the lath martensitic β' phase in the concave area, while the interior of the copper alloy wires contains a large number of reflection-twin of the β' phase. As the melt-extracted process continues, the cooling speed increases until the formation of the stable lamellar α w + β' structure. These results will shed new light on the formation mechanism of copper alloy bonding wires. [ABSTRACT FROM AUTHOR]