Portable Electronics and the Wicked Witch of the West

31 Aug Portable Electronics and the Wicked Witch of the West

Neither does great with water. I dropped my iPhone in a lake this summer and while the phone was recovered, functionality was not.  After shaking out a bit of water I pursued the traditional remedy of stashing my phone in a bag of rice and letting it sit for a day. No luck. Fortunately, I was due for an upgrade so it was off to my carrier to buy a replacement.

I could not help but wonder if Apple products are so great why they wouldn’t figure out a way to make their devices waterproof.  Furthermore, if we are trending toward digital lives centered on more compact, portable devices shouldn’t they be able to survive a dip in the pool? Not to mention marginal events such as a spilled drink or getting caught in a rainstorm.  I have a few thoughts on why we aren’t there yet.

This summer I also oversaw IPx7 testing of a new product developed at Key Tech. If you are new to ingress testing, the ‘7’ indicates that the device must survive immersion 1m underwater for 30 minutes. There is one higher class, IPx8, which consists of continuous immersion underwater for a depth and duration defined by the manufacturer. At this point we are basically talking about hermetically sealing the device. (For those curious, the wicked witch failed IPx4, splashing water from any direction).

Key Tech has developed a handful of products with strict water ingress requirements and the challenge always comes back to one rule; compromise.  The device aesthetics, features, usability, and manufacturability all run up against creating a watertight enclosure.  Every port, switch, button, screw, vent, and seam are battles waiting to be fought.  Sure there are waterproofing components and techniques that get the job done, but they aren’t always pretty.  Ever look for a waterproof USB connector? How would Jony Ive feel about adding a rubber plug to the iPhone audio jack?

My recommendation for designing a waterproof device is to start with an enclosure having a perfectly continuous surface and no ports, seams, or access points. Then resist all attempts to add any of these.  This generally will not work, so the next approach is to limit these features and spend a lot of time contemplating and testing their waterproof characteristics early in the design process.  Often you will end up relying on gaskets, doors, flaps, and plugs.  And if this is not enough then manufacturing may lean on grease, caulking and a prayer to get the job done.  Finally, the finished product may exude a characteristically “rugged” design language whether desired or not. No wonder that the favored device of 2012 (iPhone) has not greatly surpassed the popular device of 1982 (Sony Walkman) in the area of water ingress.  Good waterproof design is not easy.

The positive news is that mainstream waterproof portable electronics may not be far away.  In fact, over 90% of cellphones sold in Japan are already waterproof.  Most modern phones have embedded batteries, which eliminates an access port.  Touch screens plated with glass are inherently waterproof so long as the perimeter is well sealed.  Inductive charging is finally gaining traction and data is increasingly pushed to the “cloud” via wireless transmission, eliminating power and data ports.  Gore and others have developed acoustic vents for getting sound out of enclosures while maintaining a watertight seal.  It’s often much easier for the end user to replace a device than open it up for debugging, so manufactures have no problem  gluing or cementing joints to eliminate a major ingress concern.  A few trailblazing companies are even advertising invisible nano-coatings that are capable of waterproofing all surfaces (inside and out) on the molecular level.

Something to think about. And when you purchase your next cellphone you might consider the choice between a phone that talks to you versus one that stands up to the water hazards of daily life.


Jake Cowperthwaite

Jake Cowperthwaite

Jake is a project manager and electrical engineer who specializes in mixed signal and power electronics design. He is experienced in numerous electro-mechanical sensor technologies including acoustic, optic, thermal, and chemical. Jake has a thorough understanding of the product development process and has been involved with the design of several devices that were launched into successful products. He received a BSEE from the University of Maine and an MSEE from the University of Maryland with a concentration in microelectronics. He is a registered professional engineer.
Jake Cowperthwaite

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