11 Myths About Ruggedization and Testing to Enable IoT (.PDF Download)
A solid IoT solution encompasses a lot of working parts, and at the front end of that is developing the hardware. Marketing needs to have a firm understanding of functional and environmental requirements, and engineering must be inventive and thorough enough to incorporate all of these into the product. But the real fun begins once the first prototypes have been created and the product-development test labs start taking them through their paces.
Successful products in this space aren’t invented through an “armchair quarterback” approach, but rather ground into existence through the “elbow grease” iterations of create, test, break, fix, and repeat. Some interesting myths have developed over the years around these ruggedization and testing processes, and it’s high time that they be debunked.
1. All thermal chambers are created equal.
Visit almost any electronic hardware testing laboratory and chances are you will encounter several large thermal chambers noisily humming along. They work much like your air conditioning at home—a large compressor and furnace in the bottom and several fans that swirl the heated or cooled air around in the chamber area on top, where units to be tested are placed.
The purpose of the fans is to swirl the air around inside the chamber to ensure a uniform temperature gradient. These work great for testing hardware that’s actively cooled (i.e., have fans or blowers that move air through a heat exchanger), but they don’t work well for passively cooled items (no fan, just large-finned heat sinks that rely on natural convection to move heat away from the hardware).
Why don’t they work well for passively cooled hardware? The answer lies in all of that swirling air from those fans. For actively cooled hardware, the effect of the swirling air on thermal transfer is negligible compared to the internal fan/blower ramming air through a heat exchanger. For passively cooled hardware, the effect is too large to ignore. And worse, the data that you get is not conservative, meaning you could have the hardware pass the test in your thermal chamber but fail in the real world. Not a good situation!