Waterproffing PCBs - avaliable options - Page 1
Forum section: electronics / projects

author: hgg
author_rank: Frequent Contributor
timestamp: December 22, 2016, 04:57:54 pm
content: Hi,I am looking for a way to waterproof some of my circuit boards. I don't want to spend a lotof money on very specialized conformal coatings. What do you think about the followingsolutions :A) Plasti DipB) Urethan 71Any experience with either of the above?Other suggestions like some kind of epoxy?Thank you.

author: TheAmmoniacal
author_rank: Unknown
timestamp: December 22, 2016, 05:00:29 pm
content: Clear nail varnish / polish, easy option for small-scale water-proofing.

author: hgg
author_rank: Frequent Contributor
timestamp: December 22, 2016, 05:13:11 pm
content: Have you tried it? Does it last?I don't want something that might cause oxidation by itself.

author: TheAmmoniacal
author_rank: Unknown
timestamp: December 22, 2016, 05:18:38 pm
content: Quote from: hgg on December 22, 2016, 05:13:11 pmWorks fine for me, seems to last. Only tried one type of nail varnish though, so your results might be different. Worth trying anyway?

author: ataradov
author_rank: Super Contributor
timestamp: December 22, 2016, 07:07:24 pm
content: I've used UR71 for electronics with dew forming on it, it worked fine. But I did not do any control test, so I have no idea how helpful it actually is. It forms a nice layer, so it won't hurt, I guess.

author: hgg
author_rank: Frequent Contributor
timestamp: December 22, 2016, 07:44:24 pm
content: Good to know.I will leave the PCB in a very high humidity environment for years, so I have to make sure it will do the job.

author: ataradov
author_rank: Super Contributor
timestamp: December 22, 2016, 07:45:51 pm
content: Quote from: hgg on December 22, 2016, 07:44:24 pmIn that case I'd probably spend a bit more money and get something other than spray on coating. Or at least put as many layers as you can.

author: TheAmmoniacal
author_rank: Unknown
timestamp: December 22, 2016, 07:47:25 pm
content: Quote from: hgg on December 22, 2016, 07:44:24 pmIt's always best getting a professional product of conformal coating.Example:http://www.tme.eu/en/details/dca-200ml/protection-screen-coatings/electrolube/

author: hgg
author_rank: Frequent Contributor
timestamp: December 22, 2016, 07:51:28 pm
content: Bookmarked.Anybody that used Plasti Dip?

author: SeanB
author_rank: Super Contributor
timestamp: December 22, 2016, 07:54:32 pm
content: clear lacquer in a can ( the cheap stuff from the hardware store) applied in 4 or so coats with a drying period of 2 hours between coats, followed by a bake in a warm ( 80C oven over night), is a pretty good seal. Tectyl makes a transparent version that is the same, just in a fancy can with a slight premium, and i have used it for years on brass ornaments ( otherwise a pain to polish, and they tarnish very fast and are fingerprint magnets if you just use Brasso) to at least keep them nice on the shelf. Yes it dulls slightly with time, but it is easy to soften it with thinners and redo the polishing and recoat every few years.If your application is a humid location I would also recommend a proper 2 part polyurethane conformal coating, even though it is a lot more expensive, just for the reliability aspect. You need to make the board, clean it with solvent and test it, then bake for a few hours at 80C to dry thoroughly and then coat with the conformal coat, at least 2 coats according to instructions for multiple layers, and then baked at the recommended temperature and time to cure fully.

author: mtdoc
author_rank: Super Contributor
timestamp: December 22, 2016, 08:10:00 pm
content: I've used Plasti Dip for other things like on a car's front grill. I would not recommend it for waterproofing PCBs It does not adhere well to the underlying substrate. It will encase the material in a plastic, waterproof coating but because it does not adhere to the underlying material well it is subject to chipping or peeling away over time - especially at areas of protrusions or high curvature - thus loosing any waterproofing it may have had.

author: hgg
author_rank: Frequent Contributor
timestamp: December 22, 2016, 08:13:58 pm
content: SeanBthanks for the instructions.I think I will first try the clear lacquer with a test PCB.mtdocgood to know. Some were using it for RC stuff but I was a little skeptical.

author: tautech
author_rank: Super Contributor
timestamp: December 22, 2016, 08:33:10 pm
content: We have this PCB lacquer that's pretty useful.https://www.jaycar.co.nz/circuit-board-lacquer-spray-can/p/NA1002I use it on freshly etched bare copper to protect from tarnishing and to protect PCB's after rework.It's very liquid but flashes off to a sticky film and finally dries to a soft solder though layer.I haven't used it on "sensitive" circuits but happily apply it on most populated PCB's.Wouldn't be without it or a similar product.

author: tautech
author_rank: Super Contributor
timestamp: December 22, 2016, 08:47:30 pm
content: Really you want to use a product tailored for PCB use.Search your suppliers for "PCB lacquer".An RS search:http://nz.rs-online.com/web/c/facilities-cleaning-maintenance/electronics-cleaners-protective-coatings/electronics-varnishes-lacquers/?searchTerm=PCB+lacquer&h=s&sra=oss&redirect-relevancy-data=636F3D3126696E3D4931384E4C446573635461786F6E6F6D794272616E645365617263685465726D325F74656D70266C753D656E266D6D3D6D617463687061727469616C6D617826706D3D5E5B5C707B4C7D5C707B4E647D3F5C707B5A737D2D2C2F255C2E5D2B2426706F3D393326736E3D592673743D4B4559574F52445F4D554C54495F414C5048415F414E445F4D554C54495F414C5048415F4E554D455249432673633D592677633D4E4F4E45267573743D504342206C616371756572267374613D504342206C61637175657226Sorry for the monster URL.

author: Gyro
author_rank: Super Contributor
timestamp: December 22, 2016, 08:49:00 pm
content: Having seen many threads showing the damage to PCBs caused by leaking batteries it's hard to imagine any solid coating being reliable. Solder resist appears extremely well bonded to the board and tracks (scratch test), yet the electrolyte seems to lift it and corrode tracks with no trouble at all. What about a non hardening actively hydrophobic coating, something like Waxoyl???Actually, maybe not exactly like Waxoyl - it apparently includes Phosphoric acid rust inhibitors.

author: hgg
author_rank: Frequent Contributor
timestamp: December 22, 2016, 08:58:23 pm
content: tautechthanks for the links.

author: cjdubea
author_rank: Newbie
timestamp: December 22, 2016, 09:16:25 pm
content: I've been in the Remotely Operated Vehicle (ROV) business for more years than I care to admit.This is the stuff commonly used to "pot" parts/splices/etc for underwater usage:http://solutions.3m.com/wps/portal/3M/en_US/EMDCI/Home/Products/ProductCatalog/~/3M-Scotchcast-Electrical-Insulating-Resin-4?N=5433506+3294176988&rt=rudI've used is as deep as 5000m.chris

author: KL27x
author_rank: Super Contributor
timestamp: December 22, 2016, 09:18:29 pm
content: I started out using aerosol acrylic spray lacquer. I think brush on products are easier to use, though. Even two coats was thin. It would wear away from handing, over time. Going on thin and long dry time between coats, and having to do that outdoors, was all very inconvenient.I'm sure nail lacquer works great. But I been using MG silicone conformal coating, lately, and I love it. It goes on thick and dries fast. Compared to little bottles of nail polish, it might even be considered cheap.I have never tried using treated pcb underwater, but it works great for exposed pcb which is frequently contacted by finger oil/sweat.Epoxy coating or maybe real silicone is a must if you need solvent resistance, though. MG silicone conformal coat is removeable with alcohol/acetone and a brush, just like nail/aerosol acrylic lacquers.I have also dabbled in other "stuff," like painting the black "liquid tape" stuff on a pcb or using epoxy. But if you want to retain ability to easily rework/repair the pcb, they fall short.

author: Heszu
author_rank: Contributor
timestamp: December 22, 2016, 10:32:55 pm
content: Hi, there.I can recommend Sylgard527 Gel .. Specially the clear one.Easy to use, see trough, repairable, easy to remove.If needed to modify or repair the electronics, just pull away or even solder trough.I have used in many underwater projects, Scuba gears cameras, ROVs, Sidescan sonars, magnetometers etc.http://www.dowcorning.com/DataFiles/090276fe80190be9.pdfCheersHz