A Survey Of Long-Term Waterproofing Options

March 27, 2023 by Matthew Carlson 27 Comments

When it comes to placing a project underwater, the easy way out is to just stick it in some sort of waterproof container, cover it with hot glue, and call it a day. But when you need to keep water out for several years, things get significantly harder. Luckily, [Patricia Beddows] and [Edward Mallon] from the Cave Pearl Project have written up their years of experience waterproofing data loggers for long-term deployment, making the process easier for the rest of us.

It starts with the actual board itself. Many SMD boards have at least some flux left over from the assembly process, which the duo notes has a tendency to pull water in under components. So the first step is to clean them thoroughly with an ultrasonic cleaner or toothbrush, though some parts such as RTCs, MEMs, or pressure sensors need to be handled with significant care.

Actual waterproofing starts with a coating like 422-B or nail polish which each have pros and cons. [Patricia] and [Edward] often apply coatings to PCBs even if they plan to otherwise seal it as it offers a final line of defense. The cut edges of PCBs need to be protected so that water can’t seep between layers, though care needs to be made for connectors like SD cards.

Encapsulation with a variety of materials such as hot glue, heat shrink tubing, superglue and baking soda, silicone rubber, liquid epoxy, paste epoxy (like J-B Weld), or even wax are all commented on. The biggest problem is that a material can be waterproof but not water vapor proof. This means that condensation can build up inside a housing. Temperature swings also can play havoc with sealings, causing gaps to appear as it expands or contracts.

Overall, it’s an incredible guide with helpful tips and tricks for anyone logging data underwater for science or even just trying to waterproof their favorite watch.

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Exploring Options For DIY Waterproofing

December 26, 2017 by Dan Maloney 49 Comments

TL;DR — Don’t use silicone to pot electronics.

That’s the conclusion [GreatScott!] comes to after trying out several methods for waterproofing electronics. His efforts stem from a recent video in which he discovered that water and electricity sometimes actually do mix, as long as the water is distilled and the electronics in the drink are relatively simple. He found that the main problem was, unsurprisingly, electrolytic corrosion, so he set out to experiment with various waterproofing coatings. In a series of careful experiments he goes through the pros and cons of both conformal coatings and potting compounds. The conformal tests used simple clear nail polish on an ESC board; that worked pretty well, but it was a little hard to reach all the nooks and crannies. He also tried potting with a thick black silicone compound, but that ended up never really curing in the middle. A final attempt with legitimate two-part epoxy potting compound sealed up the ESC tight, although we doubt the resulting brick would perform well on a quadcopter.

If you want to explore potting a bit further, check out this introduction to the basics.

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A Short Introduction To Staking And Potting

October 27, 2016 by Gerrit Coetzee 41 Comments

Staking and potting are not often used in the hobby electronics world, not really entering to the common vernacular. However, everyone who’s ever busted out a glue-gun to convince that dang wire that keeps coming loose to stay has done it.

However, as [Sean Thomas] touches on, staking is not necessarily as easy as a dob of hot glue. There is a method to the madness. [Sean] gives some examples in pictures, but also directs people to the excellent NASA standard methods for staking. It’s surprising how many unintuitive caveats there are to the proper technique.

Potting, or covering everything in epoxy forever, is a great way to get a waterproof, unserviceable, and practically mechanically invincible circuit. The big challenge in potting is picking the right material. A soft silicone, for example, might transfer an unexpected force to an unexpected section of the circuit and cause a mechanical failure. A nice hard epoxy may be too insulating and cause a thermal failure. The standard RTV from the big box store has acetic acid that will eat your components.

These two techniques that come in handy when you need them and worth the bit of reading it takes to get familiar. Have you used either in your own workshop? Let us know the application and the material/techniques you have tried in the comments below.