How and where is vapor chamber cooling used?

A vapor chamber, sometimes called a planar heat pipe or heat spreader, is a phase-change thermal management tool used in high-performance electronic devices and systems with high heat-flux components, where even heat distribution is needed.

It is especially applicable where space is limited or conventional cooling is insufficient. It can be viewed as a four-step process like a heat pipe (Figure 1):

Figure 1. The structure and four operating steps of a vapor chamber. (Image: Celsia)

Vaporization: A working fluid inside the sealed chamber vaporizes when it absorbs heat.
Movement: The vapor moves rapidly to cooler parts of the chamber, spreading the heat evenly over a wider area.
Condensation: As it reaches the cooler areas, the vapor condenses back into a liquid, releasing the absorbed heat.
Capillary Action: The liquid then returns to the hot spot through a wick structure, completing the cycle without any moving parts.

What materials are used, and what are the applications?

The vacuum enclosures of vapor chambers are typically made from metals like copper, aluminum, and stainless steel. Copper provides superior thermal conductivity, and aluminum provides a lighter, more cost-effective option. Various polymers are used in new ultra-thin flexible vacuum enclosure designs for portable electronics. Inside the vacuum chamber, a porous wick structure is used to distribute the working fluid, such as water, methanol, or ammonia, that performs the function of heat spreading.

In high-performance avionics and spacecraft systems, vacuum chambers provide the needed combination of rugged compact structures and low weight. They are also being used in data centers and 5G communications to ensure uniform and stable operating temperatures.

Figure 2. Vapor chambers create a much more uniform thermal environment compared with using a copper plate to remove excess heat. (Image: DNP)

Other applications include thermal management for high-power LED lighting fixtures, GPUs, FPGAs, and other high-performance devices. More recently, vapor chambers have been developed for smartphones.

The proximity of heat-generating processors and radios to sensitive devices like Li-ion batteries in high-end smartphones is an ideal environment for using vapor chambers. Examples include the Samsung Galaxy S25, OnePlus 13, and the iPhone 17 Pro. Vapor chambers can have geometries and dimensions like a copper plate, but are much more efficient at spreading heat and creating a uniform thermal profile (Figure 2).

Fitting in

Rectangular and square shapes are most common for vaper chamber coolers. Complex or irregular custom shapes and circular designs are also used. Typical sizes are 30 x 300 mm and 75 x 150 mm.

Most applications for vaper chamber coolers focus on spot cooling and heat spreading. But some designs are 500 mm or larger to accommodate larger heat sources.

Thickness can vary significantly. Standard and high-performance devices can be up to 5 mm thick for applications like servers, GPUs, and ASICs. Designs for portable devices like smartphones and VR glasses can range from 2 mm to 0.2 mm thick.

Aspect ratio, the ratio of width to height, is an important consideration when specifying vaper chamber coolers. For standard and high-performance devices, they can range up to 60:1. Devices used in portable electronics can have much higher aspect ratios due to their extremely thin profiles.

How do vaper chambers and heat pipes compare?

Heat pipes have much smaller aspect ratios. For a simple circular design, the aspect ratio is 1:1. An 8 mm cylindrical heat pipe flattened to 11 mm wide will have a height of 2.5 mm, and an aspect ratio of about 4:1. Vaper chambers are much flatter with higher aspect ratios.

Heat pipes and vaper chambers both use phase change cooling, but the heat in a heat pipe moves linearly in one dimension, while a vaper chamber spreads heat in two dimensions. Heat pipes can be used to move heat over longer distances and to remove it from the immediate heat source to a heat sink or other thermal dissipation device (Figure 3). Vaper chambers spread heat locally to create a more uniform thermal profile.

Figure 3. Instead of spreading heat like a vapor chamber, a heat pipe uses phase change to remove excess heat along a linear axis. (Image: Radian Thermal Products)

Summary

Vapor chambers use phase change cooling to move heat in two dimensions away from hot spots, creating a more uniform thermal environment. They can be fabricated with several types of metals and even polymers for ultrathin designs used in portable devices. They are rugged and lightweight, and their thin structures result in very high aspect ratios that support compact solutions.

References

3D Vapor Chamber Assemblies, Boyd
Heat Pipes vs. Vapor Chambers, DNP Group
Phase Change, Wakefield Thermal Products
The Thermal Benefits of Vapor Chambers, Siemens
Vapor Chamber, Celsia
Vapor Chambers, High-Performance Heat Spreaders for Advanced Electronics, Cofan Thermal
Water Vapor Could Cool Your Next iPhone, IEEE Spectrum
What are Vapor Chambers?, T-Global Technology
What is Vapor Chamber Cooling?, Radian Thermal Products
What Is Vapor Chamber Cooling and What Does It Mean for the iPhone 17 Pro?, iDrop News

How and where is vapor chamber cooling used?