Thermal Paste Application

Over the past several months, I have read an unreasonable number of discussion forum posts which offer inaccurate and often times incorrect information. It's not really all that surprising to read poorly conceived information on the Internet, which seems to be an anonymous means of passing off opinion for fact. As a general rule we don't let too many things go untested, and the advice of wanna-be experts is not doing the hardware enthusiast and overclocker community any good. In this article, Benchmark Reviews dispels myth and establishes fact on the topic of proper application of Thermal Interface Material.

These days, Intel and AMD are producing very efficient central processing units that put out far less heat than prior generations. The CPU powering my primary workstation uses the Intel E8200 processor, which is rated for 65 watts using the 45 nm fabrication process. The constant production refinement has allowed the new 2.66 GHz E8200 to operate at the roughly the same Thermal Design Power (TDP) of an old P4 HT 2.66 GHz, but at the same time offer multiples more performance power. The trend of power efficient central processors is slowly making its way into graphics processors, too. The lesson we are learning in 2008 is that size matters, except that instead of skyscraper sized CPU coolers we are trying to reduce the footprint and shrink the area consumed by our systems.

After discussing this topic with real industry experts who are much more informed of the process, they offered some specific advice that didn't appear to be a "one size fits all" answer:

1. CPU Cooling products which operate below the ambient room temperature (some Peltier and Thermo-electric coolers for example) should not use silicon-based materials because condensation may occur and accelerate compound separation.
2. All "white" style TIM's exhibit compound breakdown over time due to their thin viscosity and ceramic base (usually beryllium oxide, aluminium nitride and oxide, zinc oxide, and silicon dioxide). These interface materials should not be used from older "stale" stock without first mixing the material very well.
3. Thicker carbon and metal-based TIM's may benefit from several thermal cycles to establish a "cure" period which allows expanding and contracting surfaces to smooth out any inconsistencies and further level the material.

The more we researched this subject, the more we discovered that because there are so many different cooling solutions on the market it becomes impossible to give generalized advice to specific situations. Despite this, there is one single principal that holds true in every condition: Under perfect conditions the contact surfaces between the processor and cooler would be perfectly flat and not contain any microscopic pits, which would allow direct contact without the need for Thermal Interface Material. But since we don't have perfectly flat surfaces, Thermal Material must fill the tiny imperfections. This is where our testing comes into play.

In the next few pages, which we plan to adjust and refine as necessary to meet with industry product changes, Benchmark Reviews will test several different methods of applying Thermal Interface Material to cooling equipment. The object here is simple: define the best methods to apply thermal paste, primary to central processing units. This guide will also be the first of its kind to test the proper application of material on a Heat-pipe Direct Touch (HDT) cooler, which requires a little more attention.

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