Power SO-8: An Interconnect Case Study

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With the rising cost of Au base material, many power semiconductor device manufacturers are evaluating alternative interconnect technologies to reduce manufacturing costs. In addition, shrinking package sizes, increasing electrical performance requirements and environment-friendly packaging objectives are additional considerations when choosing an alternative interconnect technology. Presently, three primary technologies compete to become the dominant Au wire replacement in the small outline, discrete power semiconductor market. Each alternative, Cu Wire, Cu Clip, and Al Ribbon, attempts to strike the best balance of electrical performance, manufacturing cost, and production yield. The small outline, discrete power semiconductor market can be broadly described as the sub-category of discrete semiconductors presently utilizing multiple 2-mil (or larger) diameter Au ball bonds as the interconnect between the die and the package leads. This paper explores observed benefits of these competing technologies in two example Power SO-8 packages that are presently ball-bonded with 2-mil Au Wire. In this comparison, we will examine the electrical performance (Rds(on) reduction), reported productivity (UPH), production yields, manufacturing cost-per-part, product-line flexibility and lead-free compliancy for each interconnect method. From this case study, similar extrapolations can be made for applying these interconnect technologies to similar packages, such as Small Outline Non-leaded (SON or PDFN), Power QFNs (PQFN), Driver MOSFETs (DrMOS), and Bi-Polar Transistor packages.