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Thermal Management Introduction: Keeping Devices Cool

As everything becomes more electrified, higher powered, and digitally connected, devices produce more heat that can limit lifetime and reliability of products. Here we introduce the idea of maintaining optimized temperatures for heat sources.

I don't know what thermal management is and at this point I'm too afraid to ask...

So, you've been tasked with the development of a new product. It's your first big project and you remember your thermodynamics from college, but your electrical engineers are telling you that your product needs thermal management and that isn't ringing any bells. Or you're the electrical engineer and have no idea where to start. You know conduction, convection and radiation but your professor didn't go into much detail about heat sinks and the practical application of cooling electronic devices. You need a thermal management introduction.

Don't worry, we've got your back. We'll explain the basics of what it is, why it's important, and some of the common ways electronics (and other items) are cooled.

What is thermal management?

Thermal management is how engineers and designers utilize different modes of heat transfer to remove heat from one place to another. In electronics, this is always away from the device.

Convection Types

Most solutions rely heavily on convection, since it is really effective for most applications. This is why we classify solutions by either natural convection (passive solutions) or forced convection (active solutions). Active solutions refer to any sort of system that forces the working fluid through the thermal management component. Most times you see this either as a pump, a fan, or a blower. Passive solutions rely on natural forces such as buoyancy to remove heat up and away from a solution. Each of these convection types have their own pros and cons when it comes to the actual application specifics.

Working Fluid

We also classify a thermal management solution based off what working fluid is used in the system. Solutions can be air, liquid or two-phase cooling solutions. Air cooling is fairly common since it is the most straightforward of the fluid types, but the cooling demands are rising past the capability of air systems where liquid systems have become more popular. Liquid has it's own complications since liquid and electronics typically do not play well together. Two-phase systems use a combination of both liquid and vapor forms of a working fluid. Some systems employ one type, some may use a combination of cooling types. All of this is relies on how the end product will be used and what works best for that application.

Ok I get it, so why is it so important?

There's a few different reasons why thermal management shouldn't be an afterthought in the design process.

For starters, we don't want any of our devices to catch on fire.

The operating temperature of the electronic device is directly related to its lifespan, reliability, and performance. Devices that run closer to their maximum operating temperature have a shorter operation time frame before they degrade. Hot silicon devices also don't perform as well. Anyone who's played some intense computer or console games know that if the computer gets too hot, you're going to experience lag. For gamers, lag can mean a life or death situation (in the game, of course). But devices that support life and safety in medical, aerospace, automotive, and defense applications, it really can be a matter of life and death. Systems that support patients, that protect us from harm, that keep us traveling safely do not have the luxury of downtime. Reliability is not optional.

Touch temperature is another key point in the user experience with your product. Devices that are too hot to handle can pose risks to the end user as well. You've probably fried yourself a bit when you were turning off a hot lamp. Or you've picked up a laptop or smartphone that's been operating too long and noticed it's super hot. Hot products run the risk of harming your end user, which does not bode well for company reputation or product sales.

I know I need some sort of thermal management solution, where do I start?

You've already taken a step in the right direction! You're looking for answers! First you need to determine what sort of fluid and convection type is available to you and your end product.

Then consider what environment your end user will subject your carefully designed product. Unfortunately, they will abuse the poor thing. You need to out-design those users.

Consider maximum and minimum operating temperatures:

  • Is your product in an enclosure? Will you have access to any flow or air ventilation?
  • What orientation will your user use your device, is it a set direction or can it be used in different directions?
  • What are your reliability requirements?
  • Can you use a pump or fan, or does that hurt the reliability of your device too much? What other project conditions has your design team or users defined?

These questions should help you get started towards thinking thermally. Genie can help on your heat sink design, but you'll need to consider the big picture as well.

As always, feel free to contact Boyd Design Engineers. We've seen a thing or two, or however many you'd see over 50 years, when it comes to thermal management.

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