Scrib-grid test on plating on plastic

[Josh2910]

Hello!

I have some questions based on the ASTM B571 in the scrib-grid test (paragraph 13) for metal coatings (electrolityc nickel) and plastic as the substrate.

Info to put you in context
- Some of the parts are too small to conduct the test since there are no proper area to perform it.
- Test performed once a month on one piece.
- Found some detached nickel on the tape on last month test.
- Some parts pass the test and others failed, even with minutes of diference in production line.

Questions:
1.- It is possible and appropiate to conduct the test?
2.- If the parts are too small to conduct the test, it is posible to do it in a coupon?
3.- It is necessary to perform the test since the substrate its plastic and not a metal?
4.- Any other test may be applied on plastic?
5.- Detached parts on the tape might have something to do with how the test is perform (strenght, scribs, angle of application,etc.)
6.- Any ideas of what might be changing since the test passed and failed from one WO (work order) to another?


Any other comments are welcome!

Thank you!

 

[IRstuff]

The fact that you have failures that cannot be explained should suggest that you do have processing issues that have to be monitored.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[WKTaylor]

Josh2910..

The way I read ASTM B571 It does NOT specifically address plated plastics. This testing appears dedicated to metal platings on metal.

Is this a decorative or engineering finish?

WHAT plastic material(s) and what metal-plating process(es) are You working with?

NOTE.
Type of plastic and the plastic surface preparation [for plating]are exceptionally important for good results.

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[WKTaylor]

Josh2910...

Might want to review following...

MIL-HDBK-700 PLASTICS
MIL-HDBK-797 POLYAMIDE (NYLON) PLASTICS: PROPERTIES, PROCESSING, PERFORMANCE, AND MILITARY APPLICATIONS

NOTE. There are many companies dedicated to plating plastics... perhaps they would have insight. I goggled "metal plating on plastics" and a number of websites popped-up for various purposes [decorative, electrical, electrical Isolation, etc].

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[WKTaylor]

Sharretts Plating Co. Company

Blog>> What Do You Know About Plating on Plastics?

http://www.sharrettsplating.com/blog/what-do-you-know-about-plating-on-plastics

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[Josh2910]

Thanks WKTaylor

Taking respond on your questions

Is this a decorative or engineering finish?
A: the finishing of the plated parts are aerospace engineering and not military (about your comments about the MIL's)

WHAT plastic material(s) and what metal-plating process(es) are You working with?

A: Mostly PPS, the metal plating proceses and layers are electroless nickel and electrolytic nickels and copper.

The detached layer seen on the microscope it is electrolytic nickel.

 

[IRstuff]

Nickel is finicky about what it sticks to. We used to have to deposit gold under the nickel.

Also, electroless nickel can get EXTREMELY stressed, to the point where a very thin layer of nickel can actually deform the substrate it's deposited on.

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[WKTaylor]

Josh2910

"...the finishing of the plated parts are aerospace engineering..." ???????? AMS? Corporate? ASTM?

Decorative ['pretty'] or engineering [EMI/RFI shielding, electrical bonding/grounding, etc?]

Plastic surface treatment [etch]?

nickel/copper alloy platings... or layered platings?

Plating failures 'adhesive' or 'cohesive'?

Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[Josh2910]

WKTaylor

we are doing the scrib test according the ASTM,
we have a 4 layer deposit being the four of them

electroless nickel
electrolityc nickel
electroless nickel
and finally electrolytic nickel

The thing is that the last layer (electrolityc nickel) is the one that comes off the substrate (PPS) by performing this test. Is actually a sign of poor adhesion or just need to change the test?

 

[IRstuff]

It comes off the electroless nickel layer underneath? You mentioned a copper layer earlier, but not now; did something change?

What happens in between the depositions?

"Is actually a sign of poor adhesion or just need to change the test?"

What is the requirement for the coating?

TTFN (ta ta for now)
I can do absolutely anything. I'm an expert!

https://www.youtube.com/watch?v=BKorP55Aqvg

faq731-376 forum1529 Entire Forum list

http://www.eng-tips.com/forumlist.cfm

 

[WKTaylor]

Josh2910... OK...

Based on Your last statement, I can reasonably assume that You are NOT plating to any referable standard: hence the platings must be per a company internal standard. NOT sure anyone can really help without knowing Your fundamental plating standard.

The fact that You refer to a standard plating ADHESION TEST protocol, ASTM B571 [which seems more appropriate for metal substrates, not plastics]... and that IRStuff has asked some very important functional questions that haven't yet been addressed... raises the issue that You might not be prepared-to [or are unable-to] provide additional specific info.

Devil is always in the details.

I think that the following forums in Eng-Tips might also widen the discussion.

Paints and Coating forum>>

http://www.eng-tips.com/threadminder.cfm?pid=332

Plastics engineering forum>>

http://www.eng-tips.com/threadminder.cfm?pid=712

NOTE: There are plating industry Q/A forums that may be better equipped to address Your unique issues.


Regards, Wil Taylor

o Trust - But Verify!
o We believe to be true what we prefer to be true. [Unknown]
o For those who believe, no proof is required; for those who cannot believe, no proof is possible. [variation,Stuart Chase]
o Unfortunately, in science what You 'believe' is irrelevant. ["Orion", Homebuiltairplanes.com forum]

 

[Josh2910]

Hi, sorry for the late response.

IRstuff
It comes off the electroless nickel layer underneath?
A: No, only the electrolityc nickel layer comes off.

You mentioned a copper layer earlier, but not now; did something change?
A: Sorry about that, my bad, the actual layers:
1.-Electroless Nickel
2.-Electrolytic Copper
3.-Electroless Nickel
4.-Electrolityc Nickel

What happens in between the depositions?
A: Depends, between electroless nickel and electrolytic copper there are only water rinses
between electrolytic copper and the second electroless nickel; water rinses, heat treatment (150°C for 1hour) and preteatment (degreasing and dexodidation).
Between the second electroless nickel and electrolytic nickel (sulfate) only wáter rinses.
and finally after electrolytic nickel wáter rinses and heat treatment (150°C for 1 hour)


"Is actually a sign of poor adhesion or just need to change the test?"
A: As i mentioned before for some instances some parts does passes the tests and some dont, even if the pieces are produced minutes away from each other.

What is the requirement for the coating?
A: Corrosion resistant and decorative finishing

I expect to answer all of your questions. Regarding all of this we are suspecting about the stress of the deposit (electrolytic nickel), but i dont know if the stress in electrolytic baths can vary that much, any comments?