Problems electroplating ABS-PC, polycarbonate, PBT, & other plastics

A. Hi Kapil. Unfortunately, many things can go wrong and lead to peeling. But I would suggest starting by reading about etching of PC+ABS on this thread and getting back to us with follow-up questions.

Luck & Regards,

A. I assume you are following the standard procedure for POP including EN/EC etc.
ABS PC needs a more concentrated and more etching time than ABS.

A. Hi Miguel. First, you want to check with GE to make certain that they consider Velox 420 a "plateable" grade of fiberglass. Second, you need to align yourself with a supplier of the process chemistry who would have the required knowledge base, or a plating shop who is good at this application.

Plating on plastics, especially on hard-to-plate plastics is something that is learned from years of experience after acquiring a good deal of book knowledge. I don't want to make it sound like black magic, but you need to recognize that there are many critical steps, any one of which can lead to poor adhesion or appearance. A starting point in troubleshooting, though, is to look at the back of the peeled foil and the part of the workpiece which has peeled, and determine what layer separated from what layer.

A. Dear KUMAR,

Chromic/sulfuric acids etchant will work for ABS/poly carbonate but to increase the adhesion it is better to use pre-etch solution. For polycarbonate it has the following composition:
tri ethanol amine 100 gm/l
ethylene glycol di ethyl ether 80 gm/l
sodium hydroxide 150 gm/l.

Best regards

A. That mixture should do the job. I suggest you run it at about 50 °C and etch for between 15-20 minutes. Make sure you destroy all the hexavalent chromium before going into the plating tanks or it will blister, peel, skip plate and generally fail. I suggest you reduce the chromium to trivalent chromium by washing in sodium metabisulphite for about 10-15 minutes, followed by thorough washing in counterflowed clean water.

A. Virtually anything can be plated, Ken, but the usual problem is that excellent adhesion is required, and that can be difficult to achieve. ABS is rather special because it can be etched in a way that leaves a sponge-like surface for great adhesion. I would suggest looking at "Standards & Guidelines for Electroplated Plastics", which will give you a full understanding of the issues and help you make a decision on how to proceed.

There are ways to electroplate polycarbonate, but as far as I know, none offer durability and adhesion comparable to plating on ABS. Then again, Ekem specializes in processes for plating on polycarbonate and knows a lot more about it than me.

A. Hi, Lajos. There are many competing technologies for applying a shiny metallic-looking coating. The choice depends on how shiny and how much wear resistance and adhesion is required. The majority of brightwork on the exterior of automobiles is chrome plated plastic, but for top adhesion you need a plastic designed for that, like ABS (I don't know if Valox is selectively etchable like ABS to bring out "tooth"). Other possibilities include vacuum metallizing and chrome-look paint. Single-sided plating should not be a problem with any of the technologies.

You can read about electroplating of plastics in "Standards and Guidelines for Electroplated Plastics". Good luck.

Regards,

A. Valox 420 SEO is a PET-PBT blend of polymers with 30% glass filler. It is possible to etch PET/PBT, but it takes some very aggressive processes. I would suggest that 420SEO is not the best material for metallising, but it will be pretty strong!
I seem to recall that GE, who originally marketed Valox, would supply it with a range of fillers, including calcium carbonate.
I would suggest that you contact the current suppliers of Valox (I believe GE recently sold off its plastics division to SABIC) and see if they still do the filled version of Valox and if so, what fillers are used. Depending on the fillers, you can pre-select your etching process to meet your needs.
Your other questions are very open ended and need to be addressed with some technical knowledge and understanding of end-uses. I would therefore recommend you take Ted's advice and get some background information on plating plastics before wanting a long series of information on a complex topic. I am sure you will be able to achieve your highly reflective surface, but you need to know what your budget is and what the product's end use will be

A. It could be temperature, what with the warm summer weather. Maybe try running the parts in the morning. You can also use less bath time but I suppose you've tried that. What you might be seeing is varying base material. That's pretty common for the type of material you are working with. You may need to write an ECO or allow a temporary deviation and try a less concentrated solution (below approved range) but that would need to be tested. Good luck, you can do it. We're all behind you.

A. Dear Ana,

If the plater says it must be the moulding and the moulder says it must be the plating, you don't have a root cause, you have an argument.

So some questions for you:

What are "spotty speckles", exactly? From your description it's hard to tell if they're little pits, blisters, discolouration...

Do these problems always appear at the same stage in the plating process or the same region of the parts? Are they genuinely all the same type of defect or have people gotten into the habit of labelling all small defects under the one category?

Has anything in the moulding process changed? Can you document this?

Has anything in the plating process changed? Can your supplier document this?

How are parts packaged and handled as they're moved between you and your supplier?