Thursday, January 18, 2024

How Phase-change Termal Pad is Working?

Thermal pads and paste play crucial roles in the cooling systems of our computers, with their formulations evolving over the years. A recent advancement in this field introduces an intriguing element by harnessing a physical phenomenon known as "phase change."


A Phase-Change Material (PCM) is a substance capable of absorbing and releasing heat during its transition from one physical state to another. In the realm of computers, Phase-Change Thermal Pads present an innovative alternative to traditional Thermal Interface Materials (TIMs) such as thermal paste. These pads undergo a transformation from a solid to a liquid state at a temperature slightly above room temperature, rendering them suitable for application in consumer electronics.

In the scope of this discussion, emphasis will primarily be placed on the Honeywell PTM7000 Series, a non-conductive material initially designed for industrial purposes, including power control units, inverters, and automotive applications. Interestingly, some enthusiasts have adopted this material to effectively cool their electronic devices.

One noteworthy example is gallium, a metal characterized by a melting point of 85.58°F (29.76°C). Alienware, a renowned brand, has incorporated gallium (Element 31) in select high-end laptops like the Alienware X15 and X17. The application of gallium in these laptops showcases its potential as an efficient Phase-Change Material, contributing to enhanced thermal management.

This shift towards utilizing phase-change properties in thermal solutions represents a noteworthy development in the ongoing evolution of computer cooling technologies. As industry leaders and enthusiasts alike explore and adopt these innovations, the landscape of thermal management in electronics continues to advance, promising more effective and efficient cooling solutions for the future.

The comparison between Phase-Change Thermal Pads and traditional Thermal Paste reveals intriguing insights into their respective advantages and applications. The PTM thermal pads, exemplified by the Honeywell PTM7000 Series, present a compelling alternative to conventional thermal paste. According to Honeywell's claims, the PTM7000 Series boasts a thermal conductivity ranging from 6 to 8.5W/mK (Watts per meter Kelvin), placing it in the realm of high-end thermal paste. Although this falls short of the remarkable thermal conductivity of liquid metal, which can reach up to 73W/mK, it still stands as a noteworthy competitor, particularly for enthusiasts cautious about the risks associated with liquid metal.


In a comparison conducted by Linus Tech Tips, the Honeywell PTM7950 pad faced off against the well-regarded Noctua NT-H2 thermal paste and Thermal Grizzly Conductonaut Liquid Metal. Remarkably, once the PTM7950 underwent its phase-change process (melting), its performance was on par with the Noctua NT-H2. The differences between the three were negligible.


Despite its commendable performance, potential users should be aware of the challenges associated with acquiring genuine Honeywell thermal pads. Moreover, the cost of a single application of PTM7950 can surpass that of high-end thermal paste. The primary advantage of PTM7950 lies in its long-term stability. Unlike even the best thermal paste, which tends to dry out and experience reduced performance after a couple of years, Honeywell has subjected the PTM7000 to rigorous testing. Through 1,000 cycles alternating between -55°C and 125°C, the PTM's thermal impedance actually decreased, indicating improved performance.


While PTMs prove to be an excellent thermal solution, especially when pre-installed by manufacturers or for enthusiasts seeking a more permanent solution without the risks associated with liquid metal, thermal paste remains a more convenient, cost-effective, and user-friendly option for the majority of users.

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