Q. I need some basic information on filtration in the plating shop. My major concern is sulfate copper and Watts nickel. Where can I find additional information on filtration? J.S.
A. Filtration of plating baths is a critical part of plating bath maintenance. Unfortunately, many plating operations only review filtration processes when they find dead fish and debris floating in the plating bath. There is much to be said about filtration but this column does not allow for extensive discussion. You can start by looking at pfonline.com. There you will find a number of good basic articles on filtration and filtration practices. You can also find vendors who sell filtration equipment.
Keep in mind there is more to filtration than just the proper filtration media, micron size and turnover rates. Carbon treatment is also part of the equation and here we get into the issue of classical batch treatment versus continuous treatment. Again, space limitation does not allow for a discussion of this topic, but let it suffice to say that batch treatment is messy, wastes part of your plating solution and if not performed properly can lead to rough deposits.
This approach has been used when the plating solution has become overloaded with what I call trash organic materials. This trash material is a by-product from the decomposition of the various additives that are added to modern plating baths. Continuation carbon filtration is a better method for doing this but comes with a price. Continuation carbon filtration will remove the “trash” but also removes some of the good additives. The problem can be partially alleviated by setting up a filtration system that filters out particles at a rapid turnover rate and filters out organics at a much lower turnover rate.