The Mechanism of Nickel Corrosion in ENEPIG Deposits And How to Mitigate it
Authors: George Milad, Jon Bengston, Don Gudeczauskas Company: Uyemura International Corporation Date Published: 9/17/2017
Abstract: Nickel corrosion in ENEPIG (Electroless Nickel/Electroless Palladium/Immersion Gold) deposits has been reported in multiple occasions. This was originally observed in cases where the desired gold thickness was in excess of 2.0 µins (0.05 µm). The boards were left in the gold bath for an extended dwell time until the desired gold thickness was achieved. In those cases, the gold ion reaches through micro-pores, that are common in thinner palladium deposits, below the palladium substrate to the underlying nickel and continues to deposit, corroding the nickel. This paper is an attempt to reproduce the defect, and to determine the necessary mitigation action to avoid nickel corrosion in the ENEPIG finish.