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Assuming that your question relates to the specific use of fans
in conjunction with heat sinks (as opposed to system cooling fans) to cool microprocessors (about 20% of our business), the practice of using fan heat sinks, (a common industry term) is wide spread. Their use came into vogue several years ago as PC manufacturers tried to retrofit the first Pentium processors into 486 boxes. Many of these systems had sufficient airflow to cool the 486 generation, but not the first Pentium processors; and computer manufacturers resorted to using
fan (active) heat sinks to provide localized cooling/air flow. This is one of the things that fan heat sinks do well - provide large amounts of airflow (cooling) in a very small volume.
The limitation on fan heat sink technology is more economic than technical. For example, computer manufacturers want high reliability (90,000 hours or greater) to enable low overall system cost. Fan reliability can range from 20,000 hours for sleeve bearing fans to 100,000 hours or greater for ball bearing fans. However, high reliability fans are expensive. Fan reliability can also be elastic to environment. Open up your box sometime and look at the dust and other potentially abrasive particles that cover everything. Thus, systems designers prefer to find passive ways to cool the microprocessor utilizing airflow provided by the system fan (which historically was associated with cooling the power electronics).
The microprocessor cooling limits of fan heat sinks is a
function of heat density, or how hot the chips get within a particular surface area and volume constraint. For instance, today's CPUs run about 3Watts/cm2 of chip surface (about 12 watts for the average chip in desktop applications). When the heat density gets up to about 12-18Watts/cm2 (about 75 watts for a comparable chip today),another technology may be required to remove the heat safely away from the chip.
Today, Aavid provides fan heat sinks in large volumes and has very active development programs in both North America and the Far East. Fan heat sinks are actually part of a larger technology focus of Aavid which is the convective (how heat moves from a surface to a fluid like air)heat transfer constraint. The key to which is simply better designs, for which we and our customers need advanced thermal design analysis software tools; and that's where Fluent's vertical market focus on electronics cooling is a major competitive advantage. Once designs are optimized on a system wide basis, and the true needs for passive or active cooling solutions are identified, Aavid's mission is to provide the required product solutions-- whatever the technology. Aavid has a well defined technology roadmap anticipating the needs of its leading customers to deliver on that mission.
Sincerely,
Alan F. Beane, CEO
Aavid Thermal Technologies, Inc. |
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