Thermal Management for tight spaces
Last week we examined a thermal interface material known as thermal grease, which is used in conjunction with heat sinks. This week we will examine a material that works in restricted places where a conventional heat sink would not work for any reason. These materials are known as a heat spreader. There are two main types of heat spreaders, T-Wing Spreaders and C-Wing spreaders. T-wing spreaders are made of flexible copper foil, weighing about 5oz. and are placed between two electrically insulating films. A high strength, pressure sensitive adhesive, made of silicone provides a strong bond with whatever component the spreader is to be cooling and, because it is flexible, is able to have nearly 100% contact with non-flat surfaces, thus optimizing thermal and mechanical performance. A C-wing spreader is similar in design but instead made with ceramics for applications where electromagnetic interference may exist. A C-wing type consists of aluminum oxide substrates, as compared to the copper of T-wing, along with the same silicone adhesive. Simply put, a heat spreader is similar to a sticker that you would place on some device in a small space that produces heat. The spreader then lets you move the heat from within the small space to areas with a larger surface area and/or volume where the heat flux is lower and thus can dissipate the heat more easily. The heat spreader can dissipate the heat to air, liquid or to the ambient space depending on the type of the design, allowing for greater flexibility with the engineering of new and more powerful parts.
Engineering Benefits of Each Wing
Seeing as the wings are designed to achieve the same goal they share a few benefits over other thermal interface materials. For one, they can achieve up to a 20o C reduction in temperature when applied to microprocessors, high density portable electronics and high speed disk drives. Also, they can be easily added to preexisting components if the thermal management technology they currently possess is not sufficient. Probably most importantly is that heat spreaders can be made in custom and complex designs, so they can be tailor made to fit any thermal management need without taking up space as a heat sink would. Both the C and T-wing are about 0.33mm thick so are very easily added to any design, and due to their peel and stick application can be used, reused and replaced as needed. The main difference between C and T-wings is that C-wings are used where Electromagnetic interference may occur. Electromagnetic interference is “the disturbance that affects an electrical circuit due to either electromagnetic induction of electromagnetic radiation emitted from an external source” 1. T-wings however are much cheaper and can be used in a larger variety of assemblies and packaging types.
Electronnics Cooling technology
As we talked about in previous blogs, the need for more effiecient components in electronics cooling will always be in demand as devices have become smaller and more powerful. Engineers are always looking for new technology or perfecting current types to achieve better results. On such company, known as Novel Concepts(TM) is developing a heat spreader known as IsoSkinTM, a stronger and more commercially available superconducting spreader that they claim can have a thermal conductivity as high as 10,000 W/m*K. Their main target is to solve the common engineering challenge of thermal management within a wick type structure that is commonly used in vapor chambers and heat pipes. Using an IsoSkin with liquid transport they are able to separate processes, such as fluid transport and heat transfer into different structures and optimize each of them individually instead of having them be dependent on each other. This is one example showing that as the demand for greater thermal management grows, the technology behind heat spreaders must also grow and adapt to create more efficient and powerful systems.
1 Based on the “interference” entry of The Concise Oxford English Dictionary, 11th edition, online