New Process And Cost Reduction Developments In Tin Silver Electroplating Of Wafers
Author: Robert S. Forman Company: The Dow Chemical Company Date Published: 1/18/2011
Pan Pacific Symposium
Abstract: The use of wafer level packaged ICs with Lead (Pb) free Tin Silver (SnAg) solder bumps is prevalent in consumer electronics. One method of making these bumps is by electroplating. The current process requires the use of a complex and expensive, single use chemistry. These chemistries do provide smooth, void free bumps, but with a very high Cost of Ownership (COO). Up to now these chemistries were expensive to operate, mainly because they are used for a short time and then disposed. This paper will discuss a new process using chemistry that provides improved COO by incorporating higher plating rates with recycling of used chemistry. With this process it is possible to recover nearly 100% of the metals, acids and organic agents previously discharged as waste. The recovered chemistry is then processed and certified to be reused in the originating fab, resulting in virtually zero waste. In addition to closed loop recycling, the process also forms bumps at a higher rate, by plating at higher current densities, with no trade-off in bump performance.
Key words: Tin Silver electroplating, SnAg, metals recycling