The United States developed a new type of thermal interface materials to help high brightness LED he
time：2017-07-29 12:40:00 browse：3922次
Polymer materials are usually heat insulator, but researchers in the United States through the electrochemical polymerization of the polymer fibers arranged in neat array, forming a new type of thermal interface material, the thermal conductivity was increased 20 times on the basis of the original. The new material can operate reliably at temperatures up to 200 degrees Celsius, and can be used in heat sinks to aid the cooling of electronic devices in servers, automobiles, and high brightness LED (light-emitting diodes). The research is published in advance in the online edition of the journal Nature nanotechnology.
As the electronic equipment becomes more and more powerful and smaller, the problem of heat dissipation becomes more and more complicated. Engineers have been looking for better thermal interface materials to help electronic devices cool down effectively. Amorphous polymer material is a poor conductor of heat because their disordered state limits the transfer of heat conduction phonons. Although the thermal conductivity can be improved by creating neat crystalline structures in polymers, these structures are formed by fiber stretching, which can lead to brittle material.
George Woodruff School of mechanical engineering Georgia Institute of Technology assistant professor Baratunde Cola said, the new thermal interface material is made by using the polythiophene conjugated polymer, its neat nanofiber arrays conducive phonon transfer, but also to avoid the brittleness of the material. The new material thermal conductivity at room temperature rate of 4.4 w / Mi Kevin, and has been at a temperature of 200 DEG C for 80 thermal cycles, is still stable performance; in contrast, solder material between the chip and the heat sink thermal interface commonly used, working in high temperature reflow process in may become unreliable.
Nanofiber array structure is made of multiple steps: first study the electrolyte containing monomer onto a block with micro pores of the alumina, and then applied to each electrode potential template, pores will attract the monomer, the formation of the hollow nano fiber. Fiber length and wall thickness are controlled by the amount of current applied and time, and the diameter of the fiber is determined by the size of the pores, ranging from 18 nm to 300 nm. The thickness of the conventional thermal interface material is about 50 microns to 75 microns, and the thickness of the new material obtained can be as thin as 3 microns.
Mr Clarke said the technology still needs further improvement, but he believes it will expand production and commercialization in the future. "Reliable materials like this are attractive for solving heat problems. This material may eventually change the way we design electronic systems."
