Development of novel immersion gold for electroless nickel immersion gold process (ENIG) in PCB applications

摘要

Electroless nickel and immersion gold (ENIG) is one of the most common final finishes used in PCBs. ENIG surfaces exhibit excellent planarity, solderability and wire bondability and tolerate multiple lead free solder reflows during assembly processing. However, the price of gold has increased rapidly from around $400 US per troy ounce in 2004 to over $1200 US in 2010. This change has increased ENIG operating costs for PCB manufacturers. While many customers have considered operating their immersion gold baths at levels well below the normal product operating ranges, making this change without proper qualification may have a negative impact on ENIG coating performance. In order to avoid such risks, we have developed a new immersion gold product, designed to operate at lower gold concentration, while ensuring that performance characteristics, including deposition rate, the impact on the electroless nickel layer during the displacement reaction and the coverage of the final deposit, are maintained at the required levels.