Michael Dube, VP of Manufacturing and Engineering, Rochester Electronics, LLC

It is critical protect functional areas of PCBs by applying surface finishes prior to assembly operations. There are several surface finishing options available in the market. One of the prevalent technologies is Electroless Nickel Immersion Gold (ENIG) which is suitable as solderable finish, aluminum wire-bondable finish, etc. It offers long shelf life (corrosion resistance) due to the presence of thin (2 micro inches: 50 nanometers) of gold layer.

Typically, cyanide containing gold salt (i.e. potassium gold cyanide) is used in the immersion gold bath. It offers stable bath and better control and repeatability. However, there are significant environment and safety concerns due to the cyanide presence in the bath.

The cyanide containing salt is known to be highly toxic substance and may be fatal if inhaled, swallowed or contacted. It is toxic to environment especially aquatic life if mishandled. It may release cyanide gas that can lead to environmental issues [1]. Moreover, electroless Nickel bath contains substances like ammonia, Pb, etc. which also pose risk to environmental and health safety.

The green (environmentally friendly) surface finish solutions are the future trend of the industry. One of the most important challenges to achieve green solution is to switch towards cyanide-free chemistry, since the cyanide containing solutions affect the operators in the manufacturing facilities and any failure of correct disposal after usage ravages the environmental balance. Currently, there is only limited options available in terms of cyanide-free immersion gold bath due to its lack of bath stability and control-repeatability performance.

LiloTree offers cyanide-free immersion gold solution with excellent bath stability and bath control-repeatability performance. Moreover, the electroless Nickel bath offered by LiloTree is also eco-friendly and doesn’t contain any ammonia (NH3) or lead (Pb) in the solution.

References
1. Willetta Lai, et. al., “High performance Cyanide-free Immersion Gold” IMPACT Conference Proceedings, October 2016.