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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Supercap Drink Coasters Are The Life Of The Party

August 5, 2019 by Tom Nardi 28 Comments

You’ve probably seen multicolored flashing LEDs embedded into clear plastic cups or coasters before, they’re quite commonly used in fancy restaurants that also feature animatronic characters and a gift shop on the way out. But have you ever wondered about the logistics of maintaining such devices? When the anthropomorphic rodent shuts down for the night, you’re going to want to clean all those blinking doodads; but any opening to connect a charger or insert a battery is just a leak waiting to happen.

[Scott Clandinin] has come up with a solution to this problem that’s equal parts brilliant simplicity and unabashed overengineering. Using wireless charging and supercapacitors, he’s developing an LED coaster that can be hermetically sealed in clear resin.

With no plugs to connect or batteries to change, these coasters can be permanently encapsulated with no ill effects. Granted the supercapacitors will degrade with time and eventually won’t hold a charge for as long, but even the most conservative estimates would have these coasters still partying in a decade.

For his prototype version [Scott] has put together a simple charging base, but we imagine in a full deployment such devices could be charged with induction coils built into a bar or table. While the energy consumption could potentially be a showstopper, we’d love to see a future version that integrates a radio receiver. Then the coasters could double as pagers to let diners know their table is ready.

While this device is obviously much thicker than a traditional coaster, it looks fairly reasonable even at this early stage. We like the concentric design that puts the coil inside the PCB, and wonder if similar cutouts couldn’t be used to get the twin 15F supercapacitors and charging module hunkered down just a few millimeters more. The 2019 Hackaday Prize is all about evolving an idea into a design suitable for production, and those are the sort of incremental improvements that the judges will certainly be keeping an eye out for.

The Dual In-Line Package And How It Got That Way

November 8, 2018 by Dan Maloney 68 Comments

For most of human history, our inventions and innovations have been at a scale that’s literally easy to grasp. From the largest cathedral to the finest pocket watch, everything that went into our constructions has been something we could see with our own eyes and manipulate with our hands. But in the middle of the 20th century, we started making really, really small stuff: semiconductors. For the first time, we were able to create mechanisms too small to be seen with the naked eye, and too fine to handle with our comparatively huge hands. We needed a way to scale these devices up somewhat to make them useful parts. In short, they needed to be packaged.

We know that the first commercially important integrated circuits were packaged in the now-familiar dual in-line package (DIP), the little black plastic millipedes that would crawl across circuit boards for the next 50 years. As useful and versatile as the DIP was, and for as successful as the package became, its design was anything but obvious. Let’s take a look at the dual in-line package and how it got that way.

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