Epoxy Removal from Gold Fingers

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 ⇦this on eBay or Amazon [affil links] 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!

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!

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.

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 [affil links] (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?

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.

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

Good Luck