Choosing Best Methods for Benchtop Thermal Testing
Chambers Vs. Thermal Platforms – “Best of Both”
If you’re constructing a new plan to test electronic or RF products, you’ll want to consider different trade-off options before narrowing in on one. For example, if you’re selecting a temperature chamber, the larger size may be a more fitting choice. This is especially true if you’re making financial commitments on testing equipment in preparation for the future.
Always try to aim for the right, most appropriately sized equipment.
Reasons to do that are as follows:
Cost – If the equipment is smaller, it will be cheaper. If the equipment is larger, it will cost more.
Operation Costs – Again, if the equipment is smaller, operating costs will be lower. If the equipment is larger, operating costs and energy costs will rise.
Hidden Costs – Large chambers typically result in heavier HVAC costs. They also use up more valuable lab space and take longer to achieve ideal temperatures. You see, with smaller chambers and items, you can conduct the work right at your workbench as opposed to taking numerous trips back and forth across the lab with larger chambers. Larger batches of parts in a larger chamber initially seem more efficient, however, in real-world testing there is often a lot of time wasted waiting for the full load to be ready.
Think through the Costs – Saving money right now always sounds like a good idea, especially if you find a sale on chambers or platforms that are currently on the market. You have to remember that going cheap doesn’t always mean you’ll get the best quality and performance in a chamber, though over the life of the system.
For example, a temperature chamber with low airflow may initially appear capable of achieving the desired temperature quickly. Appearances may fool you, and the products inside the chamber may not have actually reached that desired temperature.
Typically, that example is common in very large products.
Many chambers on the market have generic sizes, with no custom options. Generically sized chambers may also lack good user interfaces, and may offer poor or no customer support when something doesn’t work. A well-designed and supported system is critical.
Always choose equipment that uses the best heat transfer methods.
To adequately transfer heat, one or more of three methods must be properly utilized: Conduction, Convection, and Radiation.
Conduction is the most effective heat transfer method. However, conduction may not work due to the tall geometry or lack of significant flat surfaces to make direct contact with.
Convection is a great, go-to solution; it works in almost all cases. With convection, a chamber will require less prior planning and are available from many viable sources. There is less concern about managing gradients across tall packages, but like any heat forcing system, there will be some gradients. Indeed it is not possible to change the temperature without some temperature gradient.
Radiation is an effective heat transfer method, but it is more difficult to control. It’s typically only used when both conduction and convection are not viable.
The best option to choose when operating advanced temperature controllers and systems is conduction and convection combined. This will make the process fast with well-controlled temperature changes while managing gradients.
Always try to make the right cooling choice.
There are many options to consider. Ask questions or look into some of the following for your equipment.
Single-stage refrigeration is great for self-contained functionality.
Single-stage will help you remove heat, going as low as -40 degrees Celsius.
Go one step further with Cascade refrigeration, which will be more expensive, but allows lower temperatures to be achieved, typically, to approximately -75 degrees Celsius.
Liquid nitrogen cooling is great for speed and very low temperatures, going below -40 degrees Celsius. This cooling method will be an even better choice if liquid nitrogen is already in the house.
Liquid nitrogen has seemingly unlimited heat removing capabilities and fast cooling rates. It is more favorable if your parts are massive or have active heat loads. Liquid Nitrogen systems are reliable and particularly attractive due to their simple reliable nature that has fewer failure modes.
Liquid carbon dioxide cooling is less favorable, but still a somewhat good option for some. It does offer capabilities at the lowest cost per BTU, but there are a few caveats
Two of the common issues related to liquid carbon dioxide cooling correlate back to the plumbing and valves, as they tend to get plugged up with dry ice blockage or water ice during the processes.
The third common issue correlates back to the perceived environmental hazard of carbon dioxide itself. Generally speaking, carbon dioxide for industrial use will not increase greenhouse gasses because it is specifically captured from the air for the purpose, the release of the exhaust CO2 results in zero net increase of carbon dioxide.
TotalTemp Technologies offers technology and support to you directly, so that you get the best gear for your specific temperature testing needs.