Today we are kicking off a series of articles on how to select a heat sink for an OEM project. The principles are the same for overclockers building their own systems with one difference. In OEM projects, mechanical engineers usually (but not always) have a chance to simulate the design before hand and suggest changes to chassis and layout to help with airflow.
So, let’s get started with some basics. First, why is thermal management a challenge? There’s a few reasons and many of these are only getting worse if you consider them from the world of thermal engineering.
First on our list is higher frequency circuits. The International Technology Roadmap for Semiconductors notes that, “projected power density and junction-to-ambient thermal resistance for high-performance chips at the 14 nm generation are >100 W/cm2 and <0.2°C/W, respectively.” In other words, semiconductors are simply getting hotter as their clock speeds are increased.
Second, generally, semiconductors are being assembled into smaller packages. The packages are smaller, the circuits are denser and this combination means that they are warmer.
Third on our list of why thermal management is a (growing) challenge is low acoustic noise requirements. End users don’t want to be deaf just for using electronics. The result is many specifications that set a reasonable acoustic range for their equipment, often in the 100LFM to 400LFM range. This relatively low airflow is great for end users but creates a real challenge for mechanical engineers and systems integrators trying to create a solid system that meets end users needs and still operates at its optimal levels.
Fourth, circuit designers determine component placement. On the surface of this, this is how it should be. Electrical engineers have alot of pressure on them to reduce board latency and design for performance. While they often consider the thermal needs of the systems and circuits, it’s not their primary design point. For mechanical engineers that is what we do and so our challenge is the balancing act of working with EE’s to insure great placement, but also great airflow.
Fifth and finally, thermal management is a challenge because EMI shielding. Higher frequency components require better shielding and that shielding can restrict airflow.
When we pick this topic up next, we’ll cover why temperature is so important to manage. If you have any questions in the mean time about heat sinks or thermal management, contact us and lets see how can make your next project a success! Email us at ATS thermal [email protected] , call us at 781-769-2800 or visit our heat sink catalog at qats.com
