Cleaning photo resist off a PCB

Some years ago, I made some PCBs using the photo resist method. 2 were imperfect so I did not etch them.

I now want to remove the exposed photo resist so I can use the boards to make new PCBs using the press n peel film method. I want to use these since I have not done the P n P method before so I want to practice on these.

Does anyone know how I can remove the photo resist? It is a purple colour.

I tried metho but it did not work.

ljcox said: Some years ago, I made some PCBs using the photo resist method. 2 were imperfect so I did not etch them.

I now want to remove the exposed photo resist so I can use the boards to make new PCBs using the press n peel film method. I want to use these since I have not done the P n P method before so I want to practice on these.

Does anyone know how I can remove the photo resist? It is a purple colour.

I tried metho but it did not work.

G'day Len,
I have used a caustic soda/water mix in the past to do this job.
A heaped tablespoon of caustic soda [ or drain cleaner with a caustic base] mixed with a half litre of warm water. Use all PLASTIC spoons/bowls.

Soak the pcb for 10 to 15 minutes and then rinse off the resist.
EDIT:: Wash thoroughly with cold water.

Take care, goggles and rubber gloves.

Regards
Eric

ericgibbs said: G'day Len,
I have used a caustic soda/water mix in the past to do this job.
A heaped tablespoon of caustic soda [ or drain cleaner with a caustic base] mixed with a half litre of warm water. Use all PLASTIC spoons/bowls.

Soak the pcb for 10 to 15 minutes and then rinse off the resist.

Take care, goggles and rubber gloves.

Regards
Eric

Thanks Eric,
I'll try that. I have some caustic soda some where.

cheers I'm not sure if it's called the same outside the states, but steel wool and acetone works great. if this is for your press 'n peel work, the wool will give the pcb a bit of tooth as well, to better adhere the iron-on resist layer.

https://en.wikipedia.org/wiki/Steel_wool

oh, something I forgot to mention in my reply to your PM - a great tip I picked up off someone's website was to file a bevel on all the edges of the pcb, before cleaning and ironing. it doesn't have to be extreme, just enough to nock down the edges so the iron doesn't hang up on them. for a double sided board, remember to do both sides. acetone works great. I wouldn't use steel wool though. It tends to leave bits of steel in the softer copper which then rust. I just use a paper towel and wet it with acetone. A few wipes and the board is clean. A quick burnish with 600 grit paper prior to using the board will "activate" the copper(ie remove any surface oxide and increase surface area). Thanks for the advice. My wife's nail polish remover is non acetone, but I tried it anyway without success. It smells like metho.

So I'll go out and buy some acetone npr.

Thanks philba for the tip re steel wool. I've seen several references to its use for cleaning PCBs and so I may have used it.

ljcox said: Thanks for the advice. My wife's nail polish remover is non acetone, but I tried it anyway without success. It smells like metho.

So I'll go out and buy some acetone npr.

Thanks philba for the tip re steel wool. I've seen several references to its use for cleaning PCBs and so I may have used it.

Other things you might try; paint remover, paint brush cleaner, oven cleaner. Thanks for the suggestions.

I tried acetone yesterday and it took quite a lot of rubbing but most of the resist came off.

I then tried paint brush cleaner on the other PCB but it only had a thinning effect on the resist. I'll use acetone on it today.

ljcox said: Thanks for the suggestions.

I tried acetone yesterday and it took quite a lot of rubbing but most of the resist came off.

I then tried paint brush cleaner on the other PCB but it only had a thinning effect on the resist. I'll use acetone on it today.

hi Len,
Have you had the chance to try the caustic liquid

Eric

ericgibbs said: hi Len,
Have you had the chance to try the caustic liquid

Eric

No I have not tried that yet Eric. I assumed that the paint brush cleaner would contain caustic soda.

However, I discovered that if I coat the PCB with acetone and then turn it over and lay it on the glass top table for a few minutes, it rubs off very easily - not all of it comes off though. So I repeated this process a few times and have taken most of it off.

My wife was alarmed when she found me doing it on the table, I've been threatened with a painful death if I damage the table. But no evidence of damage so far. I did not use the table while using the paint brush cleaner!

So I'll try the caustic today and see if it removes the rest.

cheers,