Removal of Sn4 from acidic tin and tin alloy plating solutions can be a difficult task; it is all about optimizing filter parameters!
Sn plating is well known in electronics, as it is a popular plating process for connectors. Sn alloy plating has a wider field of application. The acidic plating processes are mainly based on sulphuric acid, MSA and fluoborate and they all have the same enemy, Sn4 sludge particles.
Managing Sn4 sludge has long been about decanting the process tank, losing both valuable production time and plating solution. And still today, people are using this method. The Sn4 sludge particle is known to block the filter quickly leading to short filter lifetime. The particle is soft and slimy and will block the filter medium, sometimes instantly.
The solution is a special Sn4 filter medium in a slightly adapted filter. Filtering Sn4 is about maximizing filtration surface and contact time without having to build a huge filter.
As always there is a big variety within plating and that is not different with Sn plating. Chemistry and parameters may vary, additional filtration might be needed as for instance anodes dissolve irregular and cause lots of metal particles that need different filtration.
It takes an expert to advise end-users what works best, including what will give them the best filtration result combined with low energy loss and a long lifetime of both filter and filter media. It’s best to consult with not only an expert in filtration, but also an expert in surface treatment! Knowing the process from top to bottom will help you to use filtration in a sustainable way!