Soluble solder mask - Page 1
Forum section: electronics / projects

author: perdrix
author_rank: Frequent Contributor
timestamp: March 28, 2021, 01:18:25 pm
content: Why oh why do PCB makers use solder mask that gets all nasty and sticky when being cleaned with isopropyl alcohol? Given this is the most likely cleaner we amateurs will use for removing flux etc. it seems a stupid thing to do.Any manufacturers out there whose solder mask doesn't do this?David

author: Bud
author_rank: Super Contributor
timestamp: March 28, 2021, 01:21:49 pm
content: I use 99.9% isopropyl and i have never had that problem

author: wraper
author_rank: Unknown
timestamp: March 28, 2021, 01:27:35 pm
content: Quote from: perdrix on March 28, 2021, 01:18:25 pmThere are none which do this to begin with as far as I'm aware. I'm 99.9% sure that you spread dissolved flux over the board and then wonder why it becomes sticky when IPA evaporates. IPA does not make flux miraculously disappear, it simply dissolves it. If you do not remove it, say with paper wipes, it will still remain on the board.

author: Siwastaja
author_rank: Super Contributor
timestamp: March 28, 2021, 01:28:20 pm
content: Never seen this problem.Maybe your IPA is contaminated, or you are spreading some crap like the solder flux residue without properly removing it and make the wrong assumption it has anything to do with solder mask.Flux residue can be a PITA to remove, depending on flux. Most flux types do not affect the board; I don't even try to remove them because it's waste of time and chemicals.

author: perdrix
author_rank: Frequent Contributor
timestamp: March 28, 2021, 04:04:34 pm
content: OK - My bad! I thought I'd washed it all off - but clearly not ...D.

author: tooki
author_rank: Super Contributor
timestamp: March 29, 2021, 12:49:28 pm
content: And it’s easy to verify: clean a board with IPAbeforesoldering it (which is actually a good practice anyway).

author: perdrix
author_rank: Frequent Contributor
timestamp: March 29, 2021, 03:27:52 pm
content: I tried that on some bare boards I have here and a few of them did get a bit stickySo not a consistent issue.D.

author: Doctorandus_P
author_rank: Super Contributor
timestamp: April 01, 2021, 01:49:25 pm
content: Are you sure you're using isopropyl alcohol?And what else is mixed through it?

author: perdrix
author_rank: Frequent Contributor
timestamp: April 01, 2021, 04:49:55 pm
content: 99% isopropyl alcohol in a spray can (butane pressurised I think).D.

author: crossroad
author_rank: Contributor
timestamp: April 01, 2021, 05:29:02 pm
content: Does it get sticky if you spray it on something other than PCB? Like your kitchen counter? I too have never came across soldermask that dissolves in IPA.IPA is an industrially recognized method to clean flux off. Soldermask are usually some sort of epoxy like material which do not dissolve in common solvents. There should be no issues unless you're using some shady board house

author: Mecanix
author_rank: Frequent Contributor
timestamp: April 01, 2021, 05:42:05 pm
content: Interesting. Most common is a chemical resistant polymer/liquid epoxy so the issue might be the type of solder mask your fab house utilized (ask them). There are a few types to my limited knowledge... for whatever reason one would want some options.

author: M4trix
author_rank: Frequent Contributor
timestamp: April 01, 2021, 06:21:32 pm
content: Here comes Captain Obvious, just use a cloth dunk in IPA and rub the board. If the cloth has colored stains (whatever the soldermask color is) then your IPA is dissolving the soldermask which means, the soldermask is low quality.

author: amyk
author_rank: Super Contributor
timestamp: April 02, 2021, 06:09:56 am
content: ...or the IPA is not really IPA/has something else in it...https://www.eevblog.com/forum/manufacture/which-plastic-is-used-for-pcb-connectors-and-plastic-parts/

author: perdrix
author_rank: Frequent Contributor
timestamp: April 02, 2021, 09:31:49 am
content: I'm pretty certain it is kosher IPA - bought under the "Pro-Power" brand name from Farnell.D.

author: opa627bm
author_rank: Regular Contributor
timestamp: April 03, 2021, 05:05:38 am
content: 1. spray alcohol2. buy esd brush or Qtiphttps://www.amazon.com/Lantee-Conductive-Bristles-Cleaning-Soldering/dp/B073WYTRDB/ref=sr_1_1_sspa?dchild=1&keywords=esd+brush&qid=1617426288&sr=8-1-spons&psc=1&spLa=ZW5jcnlwdGVkUXVhbGlmaWVyPUEyVVNDV0VZS0JKQUQ5JmVuY3J5cHRlZElkPUEwODE5NzEyMVFCTlhVOEszWVJFJmVuY3J5cHRlZEFkSWQ9QTA2NjI1ODNaOFJUM1FPVDVGNk4md2lkZ2V0TmFtZT1zcF9hdGYmYWN0aW9uPWNsaWNrUmVkaXJlY3QmZG9Ob3RMb2dDbGljaz10cnVl3. brush/ wipe it off.

author: james_s
author_rank: Super Contributor
timestamp: April 03, 2021, 05:11:05 am
content: I have never seen solder mask get sticky. I have had some flux that gets everywhere and leaves a sticky coating all over even when using proper flux remover. A few times I have resorted to submerging in acetone and scrubbing with a toothbrush to get it all off.

author: tooki
author_rank: Super Contributor
timestamp: April 04, 2021, 01:37:08 pm
content: Quote from: perdrix on March 29, 2021, 03:27:52 pmAre they HASL finished? Perhaps the PCB house leaves on flux from the HASL process.As M4trix said, if you’ve got color rubbing off with the IPA, then it really is the solder mask. But if not, then it’s definitely something else, and that something else is likely flux.Can you perform that test and report back?

author: perdrix
author_rank: Frequent Contributor
timestamp: April 04, 2021, 03:08:34 pm
content: Yes they were HASL, and no colour came off, so flux does seem to be the culprit.David

author: HwAoRrDk
author_rank: Super Contributor
timestamp: April 04, 2021, 04:43:41 pm
content: Quote from: perdrix on April 02, 2021, 09:31:49 amThis stuff?http://www.farnell.com/datasheets/1661904.pdfMaybe they put the wrong label on the can?...