30-04-2015 | | By Lynnette Reese
Lynnette Reese from Mouser Electronics discusses the basics of thermal management and some commonly used solutions, such as fans and heat sinks.
Buyers are working closer with engineers more than ever before as engineers, procurement, and suppliers collaborate to find the best possible options. As a result, buyers need a basic understanding of components' functions to achieve a common understanding on how a particular class of devices fits into the picture. Here, we discuss the basics of thermal management, some solutions that engineers commonly use, and why.
Thermal management is the practice of managing heat buildup in electronics, and is critical to maintaining the proper operation of electronics. Electronics components can generate more heat than appears possible in those tiny black packages; enough to literally burn your finger. Not only can they burn you, but they can burn themselves up, damage other components around them, and even generate smoke. Too much heat can lead to total failure, just plain poor performance, or erratic and unpredictable performance.
It's difficult to imagine exactly how much heat electronics can produce. To get a feel for how hot it can get, we used a Fluke TI-400 from Mouser Electronics to take images of several items for comparison. The included Fluke software package allows you to mouse over areas in the image and see the variation in temperatures from when they were recorded or captured by the Fluke. Figures 1 shows the heat image of a server computer's power case as recorded by the Fluke.
Figure 1. Heat image of a power case as recorded by the Fluke TI-400.
If operating above maximum specified temperatures, electronics can perform poorly or fail altogether. It is also possible for a device to get somewhat damaged by excess heat, yet continue to operate, although it will no longer operate in the same way. It might become slower or performance is somehow compromised. However, there are several ways to keep hot electronics from getting too hot. One solution is to buy products that are rated for high temperatures, but these come at a premium. Another option is to cool the devices by external means. Two main components commonly used in thermal management are fans and heat sinks.
Let's cover fans first. Active devices with moving parts like fans and blowers can be used to maintain safe operating temperatures. Moving parts consume energy, so a temperature sensor can be used to determine when to turn on the fan and when to turn it off. Ebm-papst, Inc. is a well-known fan manufacturer with many options for low noise, power-efficient fans in stock at Mouser.
Besides using a fan to remove excess heat, there are additional devices that can remove heat build-up, such as heat sinks. A heat sink has no moving parts. It is a conducting element, usually a base (like a trivet under a hot plate) that absorbs heat and disperses it over the whole area of the heat sink so it is not concentrated in one area. Typical heat sinks are fairly inexpensive, easy to use and very common, but they also add weight and bulk. It is important to note that too much heat on an integrated chip (IC), even in a small area of the chip (called a “hot spot”) can cause permanent damage. Heat sinks are excellent at dispersing hot spots and do not consume energy. Many ICs are designed to run hot, and designers may integrate a heat sink into the IC package or specify an external cooling requirement, especially for processors. Many components require heat sinks, such as LEDs. Wakefield offers heat sinks in many shapes and sizes to suit a broad range of requirements. One example is Wakefield 882 series radial fin heat sink specifically designed to work with LED packages, also available at Mouser.
Heat sinks come in many different materials, some of which might not physically appear to be heat-conductive because of the thin-ness of the material. Trimmable graphite sheets, which insulate electronics from heat sources and disperse heat
Figure 3 The Wakefield 882 series radial fin heat sink for star type LED packages.
much like heat sinks, are light-weight and are not bulky. Panasonic Electronic Components' PGS thermal graphite sheets are ideal for space-limited areas or to provide supplemental heat-sinking to existing areas.
In a way, thermal management is an insurance policy for maintaining quality because it prevents damage, which can cause poor performance. Poor performance then would be blamed on the device, not the fact that the device got too hot. Luckily, there's a plethora of products to help ensure good thermal protection. A top-level category in the Products section at mouser.com called “Thermal Management” contains thousands of products to choose from. Within all of these products lies a combination of price and value at a sweet spot that can significantly increase the overall quality of a product, reduce failures, and save labor costs without breaking the budget.