The pcb coating material--is it necessary, and are there high temp options? - Page 1
Forum section: electronics / general

author: MarkKn
author_rank: Contributor
timestamp: September 03, 2022, 04:45:44 pm
content: Very pleased to report that I received my first self-designed PCBs from oshpark, and am very pleased with how it all turned out. There are so many things I have yet to learn about all this, but building my own boards opens up a world of opportunities for electronics as a hobby.One thing I noticed, though, is that while hand-soldering the through hole parts in, the paint or plastic coating near the soldering would melt and get wrinkly. Is this coating optional, and does it serve any purpose? I know that the value-priced oshpark prototype option is a fixed configuration, but going forward I will be interested in more customized aspects. The various layers to these boards is something I look forward to learning more about. The wrinkly does not hurt anything, but I want to explore the options here.I am thinking of going without the coating on the bottom, and maybe not on the top either. To me, the gold standard of PCBs are the ones I saw on Audio Research amps, and they had no coatings on the traces, and not on the top either--as best I recall from decades ago.I note that one thing about desiging PCBs is the convenience of traces on both sides of the board. Nothing I do will be complex enough for more layers, and with the high voltage stuff, I don't think that would be workable anyway.What the heck, I will show what I did, for better or worse....Capacitor Multiplier

author: fourfathom
author_rank: Super Contributor
timestamp: September 03, 2022, 05:16:50 pm
content: That coating is probably "solder mask", and it keeps the solder from wicking down the trace, away from the junction being soldered, and also reduces the chance of adjacent-pin solder bridges. It's not as important with through-hole parts, but critical when you have a surface-mount design. But might you be using too much heat or time when you are soldering? Solder mask is pretty tough and normal soldering technique shouldn't cause it to melt or crinkle. You can specify "no solder mask", but the general default is to fabricate the boards with the mask.

author: MarkKn
author_rank: Contributor
timestamp: September 03, 2022, 05:42:00 pm
content: I suspect my soldering skills took too long and got things over-heated. Your explanation of the role of solder mask is helpful, and I imagine its key to the automated soldering of running the board over a bath of molten solder. When I build the second one of these, I will use a smaller tip on my soldering iron and eventually I will get the trick of a quick solder.

author: jpanhalt
author_rank: Super Contributor
timestamp: September 03, 2022, 07:58:03 pm
content: I usually get my boards from Oshpark. Have never had that problem with SMD or TH. Check you soldering temperature and tip size. Are you heating way too much? You will learn to like solder mask as you get into SMD and finer pitch devices.

author: rooppoorali
author_rank: Regular Contributor
timestamp: September 28, 2022, 04:16:14 am
content: Masking makes the PCB long-lasting. It works as an insulating layer for the traces. Following are some contents that you may find informative:https://www.twistedtraces.com/blog/pcb-solder-maskshttps://pcb.iconnect007.com/index.php/article/112308/thermal-capabilities-of-solder-masks-how-high-can-we-go/112311/?skin=pcbhttps://pcbtracks.com/printed-circuit-boards-quality-control/

author: aduinstat
author_rank: Contributor
timestamp: October 15, 2022, 12:00:21 am
content: Quote from: MarkKn on September 03, 2022, 04:45:44 pmNo solder mask is pretty old school, though it is also done for sensitive RF traces. You could send empty soldermask layers (and tell them that there is no soldermask), but I'm not sure that they would cost less.Quote from: MarkKn on September 03, 2022, 05:42:00 pmNah, you just get tinned traces. Might require wider trace spacing though.