Japan's Kaneka Corporation has succeeded in developing a graphite sheet based on the high-temperature sintering technology and polymer design technology using polyimides as raw materials that have the highest thermal conductivity in the world. With the growing trend of infusing more functionality into smaller sizes, the company will actively develop this as a thermal diffusion material for mobile devices, focusing on cellular phones and will sell it in the form of a product that is a composite of adhesive materials and insulation film on the graphite sheet. The company is targeting for sales of 10 bln Yen in five years and expects that through preventing irregularity of temperature in camera modules and liquid crystal displays, it will be developed to meet needs for a variety of small consumer devices and precision devices such as digital cameras and video cameras besides cellular phones.
As per the company, graphite sheet developed is composed entirely of carbon atoms and has a high level of crystallization having a thermal conductivity* about three times that of copper and about five times that of aluminium. The company claims that the graphite sheet that we have developed has the following characteristics: -
--Thinness of less than 50?m, and the relative weight of about 2g/cm3 is less than a quarter that of copper, so it is able to provide a high level of thermal diffusion effectiveness even in small spaces such as inside cellular phones or precision devices.
--Great deal of flexibility, and is superior in its punching-out ability and bendability.
--Displays stable function at temperatures even above 400°C, and its moisture absorption ratio, which is often an issue in electronic devices, is almost 0%.
--Does not contain any impurities such as degassing compounds and thus, is different from other graphite sheets.
--Displays a greater than 50dB reflectivity effect in the 1GHz or greater waveband that is important for cellular phones and other devices, and has a high level of electromagnetic shielding that shuts out electromagnetic waves over a range of wavelengths.