April 1, 2014
A New Way To Cool Off Electronics
Back before I got my new cell phone, my old phone would occasionally get so hot that I could not keep it in my pants pocket. I would suddenly feel a sense of burning on my leg, reach into my pocket, and find my cell phone burning up. Likewise, my ex-roommate’s laptop would regularly get so hot that you could not use it. He would have to set it on something like a thick clipboard or TV tray in order to sit with it. No big surprise, but electronics can get hot. This has long been a problem with such devices, and it has only gotten worse has our tech has gotten both smaller and more powerful. Fortunately, though, there may be an answer to this overheating problem.
A team from the Georgia Institute of Technology, University of Texas at Austin, and the Raytheon Company have developed a new thermal interface material by harnessing an electropolymerization process to produce an aligned array of polymer nanofibers. Normally, amorphous polymer materials are not well regarded as thermal conductors because their makeup limits the transfer of heat-conducting phonons. There are ways of improving this, but that often leaves the material brittle and not all that useful overall. This new material is made from a conjugated polymer called polythiophene, in which aligned polymer chains in nanofibers enhance the transfer of phonons without causing the brittleness of amorphous polymer materials. Thus far, this new material has been tested up to 200 degrees Celsius (approximately 392 degrees Fahrenheit). This new material could prove very useful in terms of its potential applications in vehicles and other devices that have a tendency to run hot.
This new material is developed using a multi-step process in which an alumina template with many tiny pores covered by an electrolyte containing monomer precursors has an electrical potential applied to it. Electrodes at the base of each of the pores attract the monomers and start to form hollowed out nanofibers. The level of the current and time are what control the length of the fibers and the thickness of their walls and the size of the pores controls the fiber’s diameter. They have been currently using templates that create fiber diameters of 18 to 300 nanometers. Once the fibers have been made, they are cross-linked using an electropolymerization process and the template is removed. The final product can then be attached to an electronic device using a liquid such as water or a solvent that will spread the fibers out and created adhesion between them. As it stands the technique still requires further study to fully understanding, though it is believed that it could already be scaled up for manufacture and commercialization, and a patent has already been filed for. This new material could allow for reliable thermal interfaces as thin as three microns, which is incredibly thin as the more conventional materials we use today are as much as 50 to 75 microns thick.
We will just have to wait and see where this new technology takes us, but as long as it keeps my phones from burning my leg and laptops from frying my lap, I will see it as an improvement.
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