What common chemicals can remove soldermask? - Page 1
Forum section: electronics / beginners

author: rgawron
author_rank: Contributor
timestamp: February 15, 2015, 08:34:58 pm
content: Hi all,I have a couple of PCBs that were used as electromagnetic shields (or at least I think they were), they don't have any paths nor elements, just a PCB full of copper + one hole drilled for a cable to connect it to the ground. I would like to reuse them in my projects, but they have soldermask so I can't etch them.My question is, how to remove soldermask in non-mechanical way. Is there some chemical way/substance to dissolve it? I tried isopropyl alcohol and solvent used in regular painting (purified gasoline). The soldermask stayed intact.

author: Unknown
author_rank: Unknown
timestamp: February 15, 2015, 08:36:44 pm
content: There are some info on this talk:

author: nanofrog
author_rank: Super Contributor
timestamp: February 16, 2015, 04:17:28 am
content: There are chemical strippers out there if you search, as well as service companies that will strip your boards for you. Generally speaking, the stuff is caustic. On a quick search, I foundLC8C Soldermask Stripperoffered in Europe (LC8C is the room temperature formulation; LC8H and most others require heat, usually ~50 - 60C). No idea on cost, but to give you an idea, I found a 5 gal bucket of SUREclean MS-1950 for $160USD (here).Primary ingredient of room temp versions is usually dichloromethane/methylene chloride (primary ingredient of most paint strippers). So if you're after a more DIY solution, this might be an option, along with any common paint strippers available to you locally if you've some scrap boards to experiment with.Methylene chloride isn't the most hazardous stuff to work with, but it's best to wear gloves and work in a well ventilated area (injuries usually come from inhalation, though it can also be absorbed through the skin).Also, work quickly and carefully as it ^ can damage the PCB material beneath it (i.e. apply to area with cotton swab w/ wood stick only to where you want it <won't dissolve cotton or wood>). Particularly useful for getting access to a trace, especially if you don't have the room for mechanical removal (sanding, grinding, ...) to solder a bodge wire for example.All this said, I suspect you'd end up less expensive and get better results by getting bare copper clad PCB material if you're dead set on etching your own boards. Or get a board house to make it for you (iTead Studios and so on will do it inexpensively).

author: pickle9000
author_rank: Super Contributor
timestamp: February 16, 2015, 05:03:14 am
content: Any paint stripper that contains petroleum distillates as an ingredient. In Canada one called Circa 1850 works excellent.

author: nanofrog
author_rank: Super Contributor
timestamp: February 16, 2015, 05:09:24 am
content: Quote from: cleaningOut on February 16, 2015, 04:24:56 amFWIW, the stuff I'm familiar with being used in board houses are epoxy products (cheapest method for mass production =silkscreened liquid epoxy,liquid photoimageable solder mask, ordry film photoimageable solder mask).And epoxy would explain why it's such a PITA to remove.

author: vikasbly44
author_rank: Contributor
timestamp: February 17, 2015, 08:55:33 am
content: Dear friend....I search the LC8C Soldermask Stripper offered in Europe , is the room temperature formulation. work carefully ..it can be harmful......THANKX

author: mzzj
author_rank: Super Contributor
timestamp: February 17, 2015, 10:07:16 am
content: Quote from: nanofrog on February 16, 2015, 04:17:28 amI am not sure how the European version of the paint strippers would work. Dichloromethane was banned some time ago in household diy paint strippers and many people say that for example Nitromors paint stripper is not nearly as good as earlier.Worth a try anyways since paint strippers are easy to find and cheap. You could also try to accelerate the process with hot air gun.

author: nanofrog
author_rank: Super Contributor
timestamp: February 17, 2015, 04:33:57 pm
content: Quote from: mzzj on February 17, 2015, 10:07:16 amWasn't aware of this.So what the hell does the EU expect people to use? Mud? Or is that banned as well?

author: jlmoon
author_rank: Unknown
timestamp: February 17, 2015, 05:25:11 pm
content: Acetone or Methyl Ethyl Ketone does a great job as long as boards are unpopulated.

author: wraper
author_rank: Unknown
timestamp: July 08, 2021, 07:29:32 am
content: Quote from: jlmoon on February 17, 2015, 05:25:11 pmDunno about MEK but acetone is completely useless for this.

author: exe
author_rank: Unknown
timestamp: July 08, 2021, 10:57:11 am
content: It might be easier/cheaper/safer to buy bare copper clad laminates.

author: Zero999
author_rank: Super Contributor
timestamp: July 08, 2021, 01:24:02 pm
content: Quote from: exe on July 08, 2021, 10:57:11 amI agree. Don't waste your time stripping the soldermask. Buy new bare one.

author: mazurov
author_rank: Frequent Contributor
timestamp: July 08, 2021, 06:52:48 pm
content: Hot sodium or potassium hydroxide solution might work. You must work outside, be very careful with the hydroxide, and be ready to discard the glass container after use. Below is one (not very safe) demonstration, if you decide to attempt this procedure, I suggest wearing gloves, goggles, a lab coat, closed toe shoes as well as having a bucket or two filled with water nearby, large enough to immerse your whole head into it should the need arise.https://youtu.be/gZEe9kKgncc

author: Gregg
author_rank: Super Contributor
timestamp: July 08, 2021, 07:40:47 pm
content: Oven cleaner in a spray can containing sodium hydroxide makes a fast and cheap paint and grease remover. Use rubber gloves and eye protection; probably a respirator too. The spray allows a light even coverage. try first on a scrap board if possible. Be vigilant as it may start to attack the metal under the solder mask. Rinse well.

author: magic
author_rank: Super Contributor
timestamp: July 08, 2021, 08:09:51 pm
content: No one is going to attempt anything because it's a necrobumbOn topic, I have had some luck destroying a PCB sample in formic acid and the soldermask probably was the first to go.

author: Zero999
author_rank: Super Contributor
timestamp: July 09, 2021, 08:16:10 am
content: Quote from: magic on July 08, 2021, 08:09:51 pmIt was bumped by a spammer, whos post has been removed and the account banned.Why did you destroy a PCB in formic acid?

author: magic
author_rank: Super Contributor
timestamp: July 09, 2021, 08:27:01 am
content: Just a small piece to see what happensI was trying to make sense of all the conflicting information about what chemicals "epoxy" is or is not resistant to.Then I became enlightened and realized that there are numerous so-called "epoxy resins" out there which have little in common with each other.But it stands that simple carboxylic acids (even vinegar) are surprisingly destructive to some of them (it takes a few days).DCM also weakens some epoxy resins. Indeed, the spammer recommended some magic mixture of formic acid, DCM, phenol and other stuff I forgot.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: July 10, 2021, 02:22:16 pm
content: I agree withe EXE and Zero999.Buying PCB's with bare copper is probably cheaper then a can of paint stripper.

author: Terry Bites
author_rank: Super Contributor
timestamp: July 10, 2021, 03:28:26 pm
content: Dichloromethane (AKA methylene chloride) is cheap and fast but needs to be used with care. What ever you use, dont try DMSO. The whole thing will delaminate into separate layers.A small discovery. I always had issues scraping small areas of resist off for a mod or repair to a PCB. Then I found a great tool. A diamond rod sharpener:https://www.ebay.co.uk/itm/384215684831?chn=ps&var=652435116073&norover=1&mkevt=1&mkrid=710-134428-41853-0&mkcid=2&itemid=652435116073_384215684831&targetid=1280824611018&device=c&mktype=pla&googleloc=9045880&poi=&campaignid=12128858833&mkgroupid=122141196425&rlsatarget=pla-1280824611018&abcId=9300480&merchantid=9453424&gclid=Cj0KCQjwiqWHBhD2ARIsAPCDzanWjckUQoOrkj0VOdWOmlvVUwWJtcL5UvlDQ1yUfLfX6HNIOv9WToAaAlhjEALw_wcBGets where the sand paper cant!

author: TimFox
author_rank: Super Contributor
timestamp: July 10, 2021, 04:05:16 pm
content: I've used methylene chloride to remove gunk from a tile floor, with what I thought was good ventilation (open window and floor fan), and got a horrible headache. Definitely be careful. It did work well.