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Problems electroplating polycarbonate, PBT, other plastics & blends



A discussion started in 1999 but continuing through 2020

TUTORIAL FOR NEWBIES:
ABS is the plastic of choice for electroplating because of its generally useful properties plus, because it is a mixture of 3 different resins, it's possible to etch away one of the three, leaving a sponginess to the surface which allows good "seed" sites for initiating the plating while offering great "tooth" for outstanding adhesion.
We have numerous threads about plating ABS (search the site). But sometimes other plastics offer the needed properties for an application; this thread is about plating those other plastics.

1999

RFQ: I am currently looking for a plater for nickel plating on polycarbonate, Lexan 143R, would prefer someone in the Southeast if possible. Please contact me if someone is available.

Tommy C [last name redacted due to age of posting]
- plastics - Dublin, Georgia

^- Sorry, this RFQ is outdated
     View Current RFQs




Etching and pre-etching

2001

Q. I am an amateur researcher in the field of electroplating. Would be grateful if you could give me information on the following: What chemicals/other methods can I use for pre etch and etch of --

1. Lexan 143/123 (polycarbonate)
2. Cycoloy C1200 HF (PC-ABS ALLOY)
3. Xenoy1731 (PC-PBT ALLOY)
4. Xenoy1102
5. Lexan 943

Please give me information on the chemicals involved and process chemistry of the electroless plating of metals on the above mentioned engineering thermoplastics

Thanks,

Shobhit Mehrotra
- New Delhi, Delhi, India


2001 2nd Request

Q. Hi,

What is the chemical action of chemicals like NMP or CAS in the pre-etch of PC-ABS? Any chemical equations at hand? What are the other economical methods of plating PC-ABS (CYCOLOY 1200HF)?

Shobhit Mehrotra [returning]
plastics - Gurgaon, Haryana, India



2002

Q. We are looking for advise on achieving good gold/silver EMI coating adhesion on GE plastics-Velox 420, 30% glass reinforced PBT resin (polyester). Our customer has experienced coating flaking off when submitting the coated unit to temperature cycles-not sure what temperatures, though. I am trying to qualify a new source for the EMI coating, but lack the base knowledge of the process. Any help is much appreciated. What could be causing the flaking of the coating? What are the recommendations for good adhesion?

Miguel Vallejo
- Camarillo, California, USA


2002

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.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey



2002

Q. I would like to plate on a plastic containing ABS + polycarbonate (40:60). Please suggest a suitable etchant. Will chromic acid + sulphuric acid work?

Vijaykumar S. Ijeri
- India


2002

A. Dear KUMAR,

Chromic/sulphuric 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

RAAFAT ALBENDARY
PLASTICS ELECTROPLATING - CAIRO, EGYPT


2002

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.

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK


2002

Q. Can I use some organic based Chrome reducer like Hydroxylamine HCl, Hydrazine Sulphate, Oxalic acid instead of sodium metabisulphite? In your opinion, which is better?

Vijaykumar S. Ijeri [returning]
- India



To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)



Can we find plateable Lexan grade PC?

2006

Q. We would like to know what plateable grade of Lexan or polycarbonate or other industrial grade of plastic resin such as PBT,etc. ... if ABS is not considered.

KEN WONG
lighting plastics - Hong Kong


2006

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.

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey



To minimize search efforts and to offer multiple viewpoints, we combined previously separate threads onto this page. Please forgive any resultant repetition, failures of chronological order, or what may look like readers disrespecting previous responses -- those other responses may not have been on the page at the time :-)



Chrome Plating on Valox

April 30, 2008

Q. I would like to apply a mirror like surface in mass production on an injection molded plastic part (say 10 cm2 surface area) that is planned to be made from Valox 420 SEO. Would chrome plating work? Is it possible to plate only one side of the part? Where can I read about the process in detail? What is the cost I should expect per unit? Would there be any alternative technology? I appreciate your answers in advance.

Lajos Reich
buyer - Hungary


April 30, 2008

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,

Ted Mooney, finishing.com Teds signature
Ted Mooney, P.E.
Striving to live Aloha
finishing.com - Pine Beach, New Jersey


May 2, 2008

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

trevor crichton
Trevor Crichton
R&D practical scientist
Chesham, Bucks, UK



Swellers for PC

March 8, 2009

Q. We tried several commercial swellers for PC, and adhesion is bad. Can anyone suggest any solvent or mixture of solvents suitable to swell PC ?

We are doing plating on plastics, commonly ABS. We have a new project plating with 100% Polycarbonate. With modified chromosulfuric etch (CrO3 450 g/L + H2SO4 450 g/L), it does not etch/attack the PC. Subsequently, no electroless nickel adhesion. We tried to increase the palladium concentration in the activator, but in vain. We learned that there is some kind of sweller (water soluble solvent) that might dissolve the PC and then makes the PC to be etched by this modified chromosulfuric etch. That's why we need the sweller for pre-treatment on polycarbonate. Thank you for your attention. Thanks.

Simon Lam
plating engineer - Hong Kong, China



Over-etching of PC material

July 17, 2013 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. We have tried cutting the etch bath after the concentration went to high and we are still seeing over-etching in our plastic. The bath is in range on everything. Is there something else I could try to fix over-etching?

Josh Dorris
Plating Process Engineer - Farmington, Missouri, USA


July 26, 2013

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.

blake kneedler
Blake Kneedler
Feather Hollow Eng. - Stockton, California



Brittleness after plating of PC/ABS

April 23, 2015

Q. I have an application of a chrome plated latch handle for a console. They have designed snap fit features on this part that snap into the pawl. The issue is the parts are cracking and breaking in the field at the snap fits. There is also a painted version of this that has no issues. I do notice a difference in the brittleness/stiffness of the snap fit areas on the chromed parts. Under a microscope I can see cracking occurring when the snap fit features are flexed that looks to be deeper than the just the chrome thickness. I understand that the etchant attacks the Butadiene, but does it also attack the PC? If so, is that the reason for the brittleness?

Kris Cabanilla
Automotive engineer - Troy, Michigan - USA



Spotty speckles on PC+ABS chromed parts

February 4, 2020

Q. Hello everyone!
We have a PC+ABS moulded part which is electroplated at one of our suppliers. They have the standard electroplating process including copper, nickel and chrome layers.
Recently, we had a very poor yield due to spotty speckles. It might not be the technical term, but this is the the fault name used between ourselves and the supplier. The supplier is saying that the root cause is down to the moulding process and we are saying that the root cause is the plating process.
The speckles are less than 0.1-0.2 mm in size and they are usually in a cluster formation.

Ana Matyas
- Buckingham, UK


February 11, 2020

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?

Jenna Tong
- Gloucestershire, UK

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