Barrel plating on plastics/ABS

A. Hi cousin Anil. You get an A for ambition if I am understanding that you are trying to learn the art & science of electroplating by starting with production barrel plating on plastics :-)

My guess is that you have essentially no adhesion of the electroless nickel onto the plastic. You can determine if adhesion is the problem by letting parts dry after electroless nickel plating, and putting any sort of adhesive tape on the surface and seeing if the nickel pulls off. If it does you cannot proceed further until you obtain real adhesion. You can buy tape designed for this particular purpose, but I'll bet it fails with duct tape or adhesive tape.

What type of plastic is it, and what is your cleaning, etching, and sensitizing regimen? Are you working with a reputable supplier on your pretreatment cycle, or just dipping the parts into Pd activator, or somewhere in between?

Luck & Regards,

A. Hi again, Anil. I am not an expert on pretreatment for plating on plastics, and in truth have never personally seen barrel plating of plastics, so we'll have to await input from others.

I suspect that the ABS floats, but with it etched and a layer of EN on it, I'm not sure. It should be easy enough to just put a light string/thread on a part, dip it in the copper plating tank and see whether it floats, sinks, or is unstable to get a general feel for the issue. There do exist "floating danglers" and other plating barrel styles more suited to plating on plastic than the dangler knob style. But it should be possible to experiment by lowering the solution level in the acid copper tank until the parts are just barely covered with solution so they cannot float.

It should not be necessary to do other plating layers between electroless nickel and acid copper.

Luck & Regards,

A. Hi Anil
After Etching with Chromic and Sulfuric Acid, First, make sure that the surface was etched properly by observing it in good light; it should not be shiny as it was before etching. The second important thing is that you should neutralize the possible leftover chromic acid from the part by dipping it in Sodium metabisulfite (20 gr/lit) and 5 to 10 cc per liter of Sulfuric acid. This will remove corrosive Chromium 6 from your surface; then rinse thoroughly with water, and then continue with the palladium process.

Moreover bear in mind that these days the combination of Tin & Palladium in one chloride base for better results. Add more rinsing between your steps and use deionized water for the whole process.
Good luck with your new process.

"Standards and Guidelines for Electroplated Plastics"
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A. If you are barrel plating metallised ABS, the workpiece will be the cathode. Other than that, there is no real answer because there is no detail of your problem. Barrel plating ABS requires specially designed barrels as the components are not very dense and may float.

"Electroless Plating"
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A. Dear Mr Kakkar,

When you say electroless, there is no anode. The Copper will plate by reducing on the part, which may be called the cathode as Mr. Trevor has said.

Mr. Roychowdhary, yes, I prefer the EN as it is more consistent since proprietary products are available and the copper is unstable if you are not the expert handling the bath.

A. You can barrel plate ABS once it has been metallised with an electroless metallizing system. Electroless means it does not use an electric current, so it does not need an anode or cathode. However, when an anode and cathode are used (i.e., an electrolytic system), the part being plated is the cathode and the electric circuit is completed with an anode. The anode can be either active or inert. If it is inert, it does not dissolve and can be stainless steel, carbon graphite, platinised titanium, lead etc, depending on what you are plating. If it is active, the anode will dissolve and must be made of at least one of the metals being electroplated. I agree totally with the comments above, namely that nickel is better than copper as an electroless metallizing system. Since "electroless" means it doesn't use electricity, in simple terms it doesn't need an anode or cathode; hence your original question was misunderstood. So, in answer to your second submission, firstly, yes ABS can be barrel plated and secondly, nickel is preferred to copper. I trust that answers all your problems.

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Ed. note: We have merged together several previously independent threads onto this page, Sunil and Hemant. So if you continue reading you will see responses from Asif Nurie and Bob Lynch, who sound to offer in-depth experience on your questions. Please check it out.

A. Mr. Javed Sheikh,
Here is some data that may help.

1) Plastic parts tend to float in nickel solution.
2) It is possible to process up to the final electroless stage in baskets, or any bulk system.
3) The only way barrel plating could be successful is to have parts that do not float.
4) Platers in Delhi have tried filling a barrel completely hoping for continuous contact with this packed barrel. Unsuccessful.
5) The electroless coating is so thin barrel rotation damages most of the layer.
6) The best answer to bulk plating of small parts is to design good quality, easy to handle racks (hangers) and follow the Taiwanese example of fast plating.

Use good quality solutions, well maintained, high Current densities, and you can complete acid copper in 8-10 minutes, nickel in 5-10 minutes.

A good jigging team is required to back up the speed of plating.

Regards,

A. Plating of buttons can be done using specially designed barrels with contacts all round the barrel. Has been done in Australia and I assume the barrels would be available from Europe or US. Contact barrel mfg's and tell them what you want. You do need to completely submerge the barrel in the plating solution and if you plate enough copper over the initial electroless nickel coat the buttons will sink for subsequent nickel plating.

Hope this helps.

A. Hi Ronjey; hi Sunil. As you see, we added your inquiries to a thread which answers them. But feel free to add follow up questions as needed. Good luck!

Regards,

A. Hi Sheikh. May we assume you are already proficient in rack plating of ABS, and you're just asking for what is special about barrel plating of ABS compared to rack plating of ABS? If so, the biggest issue is that ABS floats or almost floats, so special danglers are suggested. Thanks.

Regards,