Engineers developing products with embedded tech must continually explore how to achieve adequate temperature management. As today’s products get progressively smaller and more capable, those characteristics raise the probability of a device overheating if it does not have internal features that help it stay cool.
Vapor chamber cooling is one possibility that’s gotten progressively more attention. Vapor chambers have flat structures that aid in transferring heat evenly throughout a small space. Plus, they contain a fluid that evaporates into a gas once it gets hot enough. The chambers also have small posts that keep the structure from collapsing due to exterior atmospheric pressure and guide the fluid to the correct places.
One thermodynamic difference between a vapor chamber and a conventional heat pipe is that the vapor chamber transfers heat in two dimensions instead of one. Engineers typically use them to spread heat from its source to a heat sink’s fins.
Moreover, effective thermal conductivity relates to thermodynamic properties and the vapor space’s thickness. As the vapor space gets thicker, the flow pressure drop becomes less prominent, which increases the effective thermal conductivity.
Many desktop computers have heat pipes welded on top of vapor chambers, which further aids in efficient heat transfer. However, some designs place heat pipes into the vapor chamber, streamlining the whole process. Since some vapor chambers are as small as 1 inch by 1 inch, they suit projects that demand small package sizes. Also, their standard thickness is 3-9 millimeters, facilitating inserting them into an existing base.
Weighing the Pros and Cons
Transfer efficiency is one of the primary benefits of choosing vapor chamber cooling over other methods. It can dissipate up to 2,000 watts of heat within an area of approximately 4 square centimeters. Engineers also select it to help with reducing hot spots or dealing with high power densities in small packages.
Additionally, vapor chambers tolerate direct contact with heat-producing components, such as central processing units (CPUs).
However, disadvantages exist, too. For starters, vapor chamber cooling may be more expensive than heat pipe methods. If used for high-volume consumer products, the overall manufacturing costs might be prohibitive. However, implementing vapor chamber cooling technology could pay off for particular applications such as embedded systems with critical thermal management concerns. Weighing cost considerations with performance necessities helps engineers decide if the extra cost is worthwhile for a particular project.
The traditional two-piece vapor chamber design includes two stamped copper plates. That type is costlier than most heat pipes, although there are now single-piece designs. As demand for those has climbed, costs have dropped to approximately the same costs as some traditional heat pipes.
From manufacturing costs and availability perspectives, vapor chambers have some downsides. Most designs are customized and produced at relatively low volumes. The lack of standard designs increases project flexibility, but it can also increase cost. However, researchers have investigated using additive manufacturing for some vapor chamber components. That could increase availability and lower costs.
Smartphones represent a product category whereby people progressively want the latest models and expect those options to do more for them with each release. Some company leaders hope vapor chamber cooling could enhance the capabilities of their new models.
Apple is reportedly testing the cooling method for its upcoming models.
An analyst familiar with the matter believes the brand would need it to keep up with the more demanding characteristics of 5G phones. They noted that previous reliability tests fell short of Apple’s expectations but believe the tech brand may aim to incorporate the option in a future model. If so, the cooling method could improve processing power while extending battery life.
Microsoft also recently patented a system involving flexible vapor chambers attached to the hinges of foldable phones. The patent filings suggest the tech brand would use that approach to keep folding dual-screen devices cool.
Some smartphones already contain vapor chamber cooling. One of them is the Sony Xperia Pro.
A tech teardown of the device confirmed that it has a metal piece acting as the interface with graphite sheets that wick heat away from the phone’s components, including its 5G antennas. The metal sends the heat to a vapor chamber that’s almost as tall and wide as the device itself. Finally, the chamber passes heat out through the device’s screen.
Engineers are also interested in applying vapor cooling to laptop designs, particularly with more consumers using them for intensive gaming. The primary advantage of vapor chambers in these use cases is that they allow for thinner designs. When engineers choose heat pipes for cooling, the computer’s design often features three to four of them to move the heat.
However, choosing a vapor chamber cooling design instead allows doing away with multiple closed-loop heat pipes. Then, a single chamber performs the same function as several heat pipes, thereby allowing thinner laptop designs.
A vapor chamber lets hardware designers sync lower-level thermal loads to the main heat sink by making them have direct contact with the vapor chamber. That option gives storage and memory components a straight path to any fanned or finned heat sinks used for a design.
Laptop designers have selected vapor chambers to cool those gadgets over the last several years. Evidence connected to a recent gaming laptop model shows the temperature-related changes that can happen.
For example, the Dell Alienware m15 R3 features vapor chamber cooling. An extensive review of the model compared the temperatures associated with it versus the previous R2 model. Testers confirmed that the R2 model temperature stabilized at 99° Celsius (C) and 70° C for the CPU and GPU respectively, even when using the laptop’s Turbo fan feature. However, with the R3, the CPU and GPU temperatures stabilized at 73° C and 65° C respectively. The reviewers cited the vapor chamber cooling as the most likely reason for that change between models.
Combining Cooling Methods
Engineers who are interested in exploring vapor chamber cooling methods for their projects should bear in mind that such solutions can support other temperature control options rather than replacing them.
For example, a recently released Acer gaming laptop features a sliding keyboard that reveals a glass panel. That design feature lets users check out the cooling technology without disassembling the computer.
Besides a vapor chamber, the cooling technology includes three copper heat pipes, fans, and vents near the screen. The model also has Acer’s PowerGem technology, which takes a different approach than the common practice of placing CPUs under a layer of thermal paste that pulls heat away from the chip. PowerGem uses a pad that Acer claims works several times better than copper.
Cooler Smart Lighting
Research also suggests that vapor cooling could address some of the challenges associated with Internet of Things (IoT) lighting systems that use LED bulbs. A team that investigated the matter indicated that the additional electronics required for the communication, control, sensing and power aspects of the IoT features could add up to 70% to the total heat generated during operation compared to if the products did not have those connectivity features.
Moreover, if the heat increases by 70%, the maximum temperature of electronics increases by about 25%, the researchers found. Thus, it becomes even more crucial to deal with hot spots brought about by the overall higher temperature found in IoT bulbs.
However, one of the recommendations from the research was to develop a heat spreader substrate based on vapor chamber technology. Tests showed that such options provided nearly 25% better thermal performance than non-vapor-chamber solutions when placed at the front of a printed circuit board rather than the side. Moreover, investigations indicated that using vapor chamber systems could address LED temperature elevations due to local heat generation and limited heat transfer paths.
This example shows that choosing vapor chamber cooling is only the start of project planning. Engineers must also explore other factors that cause temperature rise or associated cooling effects.
|Emily Newton is a technology and industrial journalist who enjoys discovering how the IoT is impacting different industries. Emily is editor in chief of Revolutionized – an online magazine exploring trends in science, technology and industry. Subscribe to her newsletter to keep up with the latest.|
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