April 13, 2015
There is a difference between saying an electronic device works for a given temperature range and actually proving it. Without testing it, there can be unexpected failures on a cold day when you are out in the field trying to optimize your well. This can be incredibly frustrating and there is likely little you can do by the time you find this out. Make sure to ask up front how the manufacturer has tested the product to ensure it will work at extreme temperatures.
When designing a product, components are selected to perform each function required. All of the components together make up the design. In theory, as long as each component meets the temperature requirements, so should the entire design.
The problem is that a designer may select a component that doesn’t quite meet the requirement, they may select a component with the wrong temperature range, or they may not account for a degradation in performance at extreme temperatures. Regardless of the reason, when the product has been built, there is a good chance that there are going to be problems at either the extreme cold or hot temperatures. So how do we at ETC ensure that a device actually works across a wide range of temperatures before installing it at a well site?
There are often many different manufacturers of a given component. Selecting components with better performance at a wide range of temperatures will ensure that the final design performs the same, regardless of temperature. You may need to pick components that use a different technology or materials to get the range you need. In addition, each manufacturer may make the same part available with different temperature ranges. This is typically broken into commercial, industrial and military. Select the component that has a range that covers your requirement with a large margin for error. This will ensure that you meet or exceed the requirement under the worst conditions.
Never assume that the design is right, that you actually received the components you ordered, or that the manufacturer delivers the performance that they promised. The only true way to ensure that the final product performs within the range you have specified is to test it.
Owning or renting an environmental chamber will allow you to drop the temperature to the minimum or raise it to the maximum. You will want to ensure that you go well beyond these limits to truly make sure your specifications can be trusted. Make sure that you soak the product at a given temperature long enough to ensure that each and every component on the design has stabilized at the desired temperature. If the test is too short, you may be surprised in the field when you get a cold snap for several days and your product fails.
Another thing that is often overlooked is the effect of temperature cycling. As the temperature increases and decreases during different hours of the day or from season to season, stresses are put on the components on the circuit board. This is especially important when using any kind of potting that can expand and contract. Solder joints can be weakened or broken, leading to product failure. Once again, the only way to catch these problems during product development is to cycle the temperature over the course of days or weeks.