Heat-conductive noise suppression sheet

Abstract

A heat-conductive noise suppression sheet according to an embodiment includes first ferrite particles, second ferrite particles, a heat-conducting material, and a matrix material. The first ferrite particles are spherical particles having an average particle diameter in the range of 50 μm to 150 μm, the content of the first ferrite particles with respect to the total amount of solid components being in the range of 5 vol % to 25 vol %. The second ferrite particles are irregularly shaped particles having an average particle diameter in the range of 50 μm or less, the content of the second ferrite particles with respect the total amount of solid components being in the range of 5 vol % to 45 vol %.

Description

CLAIM OF PRIORITY[0001]This application is a Continuation of International Application No. PCT / JP2009 / 062377 filed on Jul. 7, 2009, which claims benefit of Japanese Patent Application No. 2008-179664 filed on Jul. 10, 2008. The entire contents of each application noted above are hereby incorporated by reference.BACKGROUND OF THE INVENTION[0002]1. Field of the Invention[0003]The present invention relates to a heat-conductive noise suppression sheet having a high noise suppression effect over a wide frequency range from the hundred megahertz range to the gigahertz range and high thermal conductivity.[0004]2. Description of the Related Art[0005]As described in Japanese Unexamined Patent Application Publication No. 2001-68312 and Japanese Unexamined Patent Application Publication (Translation of PCT Application) No. 2006-504272, structures in which a heat-conductive noise suppression sheet is interposed between a semiconductor component, such as an IC, and a heat sink are known.[0006]A ...

AI Technical Summary

Benefits of technology

[0029]According to the heat-conductive noise suppression sheet of the present invention, a high noise suppression effect can be obtained over a wide frequency range from the hundred megahertz range to the gigahertz range. In addition, high thermal conductivity can be obtained.

Problems solved by technology

However, it has been found that it is difficult to effectively increase the noise suppression effect in both the hundred megahertz range and the gigahertz range simply by adjusting the imaginary part μ″ of the complex relative permeability.

However, it has been found that even when the coefficient of thermal conductivity is increased by increasing the content of filler, the thermal conductivity cannot be effectively increased, owing to a reduction in compressibility.

If the compressibility of the sheet is low, the adhesion between the sheet and the heat sink and the adhesion between the sheet and the substrate decrease, which causes a reduction in thermal conductivity.

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