Specification for Electroless Nickel/Immersion Gold (ENIG) Plating for Printed Circuit Boards Amendment 1 to IPC-4552 replaces the Table 3-1 Requirements of Electroless Nickel Immersion Gold Plating plus also replaces all of sections 3.2.1 Immersion Nickel Thickness and 3.2.2 Immersion Gold Thickness in the original release of the IPC-4552. The Amendment 1 permits the use of thinner gold (≥4 µm thickness minimum) for special applications. Effective June 2012.