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topic 10780

Epoxy Removal from Gold Fingers


 

Q. Hello,

I also would like to remove a cured epoxy off some gold contact fingers for a circuit module w/o damaging the fingers. I have tried acetone, citric acid based solvent, and a few industrial cleaners with no luck. If you have any thoughts, please do reply.

Mahesh N [last name deleted for privacy by Editor]
medical systems - Waukesha, Wisconsin


 

A. Mahesh,

I was hoping that by now someone would have given you an Einstein-ian response to your question ... which is why I didn't reply earlier on.

Removing epoxy by solvents is a pig. Have you tried to get some advice from a) the local fibreglass resin suppliers or b) from Esso? ... who make the Epon epoxies.

You said that you used acetone but that's a polar solvent and not nearly as vicious/effective as are chlorinated hydrocarbons. Try Toluene (or is it toluol, I get mixed up), Xylene or Chloroform.

As these solvents evaporate rather quickly you might try to reduce the evaporation speed by adding a mini drop of oil. I've never, ever seen epoxies, vinyl esters or polyesters removed except by 'sanding off' and am truly ignorant about solvent removal because, especially epoxies, there's little to quickly attack them except for strong acids.

Lots of luck!

freeman newton portrait
Freeman Newton
White Rock, British Columbia, Canada

(It is our sad duty to
advise that Freeman passed away
April 21, 2012. R.I.P. old friend).



----
Ed. note, Feb. 24, 2012: Per www.cbc.ca/news/health/story/2012/02/24/bathtub-refinishing-deaths.html
"Methylene chloride ... has been linked to the deaths of 13 workers refinishing bathtubs in the United States...
To use products containing methylene chloride safely, work areas must be well-ventilated, and when levels of methylene chloride exceed recommended exposure limits, workers must use protective equipment ...
The finding has prompted the CDC to warn ... public health agencies, manufacturers and trade groups to 'communicate the extreme hazards' of the use of the chemical -- also known as dichloromethane -- to employers, workers and the public."


Dad's Easy Spray Paint Remover

 

A. Try Methylene Chloride. That is what I have used to strip epoxy. You must soak the part with epoxy in the solution. It is a volatile solution, so you will have to cover the container while waiting for it to work. If the amount is small, it might take just an hour or so. If you really have a large glob of epoxy on the gold fingers, you might have to soak it over night. I assume you have removed as much mechanically as you dare and are just trying to get rid of the residue so you have good electrical conductivity again?

I should add a caveat. If your circuit board is made of G-10 fiberglass reinforced epoxy resin, you should try the methylene chloride on a sample FIRST! If you soak an epoxy-based circuit board in this solution, it may damage the matrix. Try epoxy removal on a sample circuit board before treating the board you are trying to save.

Good luck!

Ronna Erickson
- Amherst, Massachusetts


 

A. I know it is an expensive solution, but a YAG laser will remove the epoxy and not hurt the gold. Lasertronics has a small system that could be used to do so.

Douglas D [last name deleted for privacy by Editor]
Air Force, WR_ALC/MANPT - Robins AFB, Georgia, USA


(2007)

A. Hi - a pic of the part you are trying to clean would be helpful but I am assuming it is flat like a sound card for a PC, for example? if it is, you can try covering the epoxy coated contacts with a commercial paint/varnish remover - one that contains dichloromethane, DCM (methylene chloride) and methanol (methyl alcohol) in a polymer/wax thickener works best. these are pretty viscous and the evaporation rate of DCM is reduced, making it more effective/aggressive in attacking the epoxy.

costs about £5/$10 and tin and I use this almost every working day to clean thermo-set epoxy from PCBs - the normal everyday kind of PCB you would find in any pc or appliance. apply it fairly liberally, wait a minute or two and scrub off carefully with a sharpened bamboo stick or small horsehair brush (with bristles cut to about 5-10 mm). may need to repeat application for complete clean depending on how thick the layer of epoxy is.

wipe away residues and clean contacts with (lint-free) cloth(s) soaked with IPA (isopropyl alcohol/2-propanol). this process will not affect the pcb, solder, most components or metal parts but avoid contact with plastics. avoid skin contact, too - nips a bit!

if your part is not flat then I don't know how successful or applicable this would be?

kenny d
- glasgow, Scotland, UK


February 12, 2008

Q. Kenny, I'm very interested in removing epoxy from a fibreglass housing without damaging the housing. What kind of epoxy in particular did you remove using the methylene chloride solvent mix? I believe circuit boards are made with epoxy, no? So you must have found a variety of epoxy that dissolves more readily, which I could use. Or am I wrong about circuit boards?

Matt C

Matthew C. Cook
- San Leandro, California, USA


"Attack" solvent

January 22, 2009

A. Dimethylformamide will remove epoxy (or any type of synthetic plastic for that matter) but is a very toxic chemical which requires special safety precautions. Don't even think about using this chemical until you have read the MSDS and clearly understand the hazards and precautions associated with this organic solvent.

A less potent version is available from many lapidary suppliers, sold under the name of "ATTACK" which is a dilute solution of DMF and acetone. Again, be careful as DMF is a known carcinogen and WILL fry your liver and kidneys--Hope this was helpful--Les M. Barnes, L.A.C.

Les M. Barnes
- Carolina Beach, North Carolina


May 1, 2009

A. I believe a product that will work for is called ATTACK and can be purchased at most jeweler supply houses

Good Luck

Richard Shaw
- Old Saybrook, Connecticut, USA



October 29, 2009 -- this entry appended to this thread by editor in lieu of spawning a duplicative thread

Q. How to remove a cured epoxy from a ceramic tile surface?

Raghavan sridharan
seller - chennai, tamil nadu, India


February 23, 2013

Q. We have an assembled printed circuit board with peeling varnish. Please suggest some varnish remover which removes only varnish not letters/symbols on electro radio elements.

SAK B
- Hyderabad, INDIA



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