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Maintaining and Monitoring Acid Copper brighteners

(-----) January 31, 2008

The hardness of the copper plated layer is key to subsequent processes and it has been suggested that the levels of "copper brighteners" modifies the hardness.

Researching it is apparent that the monitoring and maintaining the concentration of the brighteners is difficult as the consumption and concentration cannot be monitored directly.

Is there a method of controlling the brighteners more accurately and through direct measurement to remove the guess work?

Many thanks

Ant Lervel

Anthony Lervel
Production Engineer - UK
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January 30, 2008

The plating world, like the rest of the world, moves technologically upscale over time, Anthony, so you may find procedures like CVS entirely practical, which a couple of decades ago were considered advanced.

But at the more down to earth level, the first tool is a Hull cell. While it doesn't directly measure brightener concentration it does directly measure its effect, and it shows you when things are trending in the wrong direction so you have time to react. The second tool is a "brightener feeder"; this is a simple small pump connected to an ampere-hour meter, allowing you to inject brightener in direct proportion to its consumption. Good luck.

Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey
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February 4, 2008

Ant

Unfortunately, your simple question does not have a simple answer. 'Brighteners' and other additives are usually complex organic chemicals and are not amenable to simple analysis. To make matters worse, they can break down in the solution and the resulting chemicals themselves may or may not be active in the plating process.
Analysis is possible using techniques like polarography or HPLC but you would need a chemist to operate them and to interpret the results.
Two suggestions;
Go with Ted's suggestion of a dosing pump and determine the optimum rate by applying a little statistical process control SPC.
Ask the supplier. They know what the brightener chemicals are and may have an analytical method. My bet is that they will advise that you use a Hull cell. At least they will tell you where to get one and the correct way to use it.

Geoff Smith
Hampshire, England
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