How to erase WHITE TEXT from a PCB

I have some PCBs from which I would like to remove the WHITE TEXT on the component side as well as the copper layer side.. As it is hiding some tracks.. I do not want to scratch it as the mask will come off..

What chemical will remove the texts.??

You probably won't be able to - not without damaging the PCB or the solder mask.

Its some kind of paint. You could try paint thinner, mineral spirits, turpentine. Are you trying to modify the traces underneath?

It is unlikely any of those will work. The "paint" is resistant to neat isopropanol (isopropyl alcohol) which is used to clean PCBs.

It might be worth trying white spirit or acetone - they will dissolve many things that isopropanol won't.

Might dissolve the solder mask too though... Soldermask is tough, so fine emery paper might remove the paint before the solder mask is too badly scratched? For small areas a sharp knife / scalpel could be used to carefully scrape the paint away.

MarkT: Might dissolve the solder mask too though...

Maybe do a small test before dunking the board...?

The white legend or silk screen layer is not soluble in any solvent you'd want in your house and in a special locker if at all. The paint is usually a 2 part epoxy and in 40 years of doing PC boards I've never managed to remove it as a process with any solvent including various concoctions containing chlorinated hydrocarbons... It is most tough, It has to be to look pretty after the shake and bake of PCB assembly and testing...

Aqua Regia (nitro-hydrochloric acid) will get it off. It'll also get off the solder mask, the copper tracks, the skin from you hands, the muscles from your bones, the bones from what's left of your hands... Nasty stuff...

That or for small "corrections" a Dremel or motorized hobby grinder works but it is sure a lot of work and short of "Water of Kings" about the only thing I've ever found that did

Docedison: The white legend or silk screen layer is not soluble in any solvent you'd want in your house and in a special locker if at all. The paint is usually a 2 part epoxy and in 40 years of doing PC boards I've never managed to remove it as a process with any solvent including various concoctions containing chlorinated hydrocarbons... It is most tough, It has to be to look pretty after the shake and bake of PCB assembly and testing...

sonnyyu: Dissolve epoxy resin might be day to day job for people do reverse engineering.

There are off-the-shelf epoxy resin dissolver solvent available;-

"Attack" Epoxy Resin and Adhesive Dissolver Solvent Remover & Cleaner

www.esslinger.com, $12.95

Safe for use on metal, stones, glass, and wood

The plastic is missing here, since solvent might be very aggressive to most types of plastic.

I guess either holohil.com replace new case or use customer solvent which safe for case.

Your university has chemical department? It should be a piece of cake jobs to make customer solvent.

Don't forget that the solder mask and the PCB itself are probably built from the same plastic (epoxy) as the silkscreen ink.

The reason I say that you don't want them in anything but an isolated fire buffer is that those chemicals are toxic... to most of the body, liver spleen and kidneys. Really strictly bad news for certain types of black Epoxy used to pot some TI TMS 7K processors and the roms were potted most carefully... But that was 30 years ago. Perhaps things are different now. Bad News chemicals. Then.

Doc

Docedison: The reason I say that you don't want them in anything but an isolated fire buffer is that those chemicals are toxic... to most of the body, liver spleen and kidneys. Really strictly bad news for certain types of black Epoxy used to pot some TI TMS 7K processors and the roms were potted most carefully... But that was 30 years ago. Perhaps things are different now.

Do you know what "ROHS" stands for?

fungus: Do you know what "ROHS" stands for?

Really Obtuse High-cost Standard.

A system imposed by bureaucrats who don't have a clue about the real world - they just sit there in their ivory towers having their egos massaged by a dozen spotless virgins passing down idiotic dictates that make no sense at all to us proles.

And anyway it's RoHS.

Still haven't seen a reason from OP as to why stenciling needs to be removed.

Re-branding?... Or fixing a Boo-Boo... The easiest method is to color match or get from the MFR a small amount of the soldermask or a similar coating and mask out the unwanted "artwork"

Doc

mechanical method;-

sonnyyu: ... for anti-reverse engineering, We could do much better than erased label by sandblasting or sand paper. I could offer some type of help advice, since my previous life has some thing to do with ic bonding/package/labeling ( I know-who ). ...

Erasing a label? the poster was talking about PCB silk or legend layer(s) which was the reason I suggested the solder-mask color, to "mask" the unwanted text. If the boards aren't assembled yet the layer could be re-screened.. Kinda pricey though.

Doc