JP2006093526A - Conductive thermally conductive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To solve the problem that the high-frequency characteristics of equipment can not be satisfied in the case of using a thermally conductive graphite sheet used as a heat radiation material for the heat radiation of a semiconductor device such as high-speed communication equipment since it has the resistance value of several Ω though the main component of the constituting material is carbon and it is conductive. <P>SOLUTION: By disposing slits passing through the thermally conductive graphite sheet to the thermally conductive graphite sheet of high thermal conductivity and a high orientation property and attaining the conductive thermally conductive sheet for which a conductor is disposed on the entire surface of the thermally conductive graphite sheet including the inner surfaces of the slits passing through, high thermal conductivity characteristics and low electric resistance value characteristics are provided and there are the effects of taking measures against heat and satisfying the high-frequency characteristics of electronic appliances and the high-speed communication equipment. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to a heat conductive graphite sheet used for heat dissipation of electronic devices and high-speed communication devices, and also relates to a conductive heat conductive sheet having low electric resistance characteristics.

  Conventionally, this type of heat conductive sheet has a structure as shown in FIG.

  FIG. 5 is a plan view of a conventional heat conductive sheet, and FIG. 6 is a front view of a usage example of the heat conductive sheet.

  In FIG. 5, the heat conductive sheet 6 has a fixing screw notch 7 and generally has a thickness of about 0.05 mm to 0.2 mm.

  In addition, as shown in FIG. 6, the thermally conductive sheet 6 is sandwiched between the semiconductor device 12 having the connection terminals 11 and the metal substrate 10 and the heat dissipating metal substrate 8 and fixed with a fixing screw 9. Is used as a heat dissipation member.

  With the above-described configuration, the semiconductor device 12 and the heat dissipating metal substrate 8 are thermally connected and at the same time are electrically connected.

As prior art document information related to the invention of this application, for example, Patent Document 1, Patent Document 2, and Patent Document 3 are known.
Japanese Patent Laid-Open No. 10-229149 JP-A-10-070350 JP-A-5-235215

  As electronic devices have been downsized and improved in performance in recent years, heat generated from high-density integrated semiconductor devices and the like can be efficiently dissipated, and at the same time, the frequency can be increased like FETs in high-speed wireless communication. In order to use the space between the semiconductor device 12 and the heat-dissipating metal substrate 8 as a ground, it has been required to have a low resistance value as the electric resistance value between the semiconductor device 12 and the heat-dissipating metal substrate 8.

  However, in the above-described conventional configuration, the main component of the heat conductive graphite sheet 6 is carbon, which is conductive, but has a resistance value of several Ω. There was a problem that defects occurred.

  There is also a need for a thermally conductive graphite sheet with better thermal conductivity.

  The present invention solves the above-mentioned conventional problems, sandwiched between a semiconductor device and a heat-dissipating metal substrate in an electronic device / high-speed wireless communication device, through a heat conductive graphite sheet excellent in heat of the semiconductor device, When dissipating heat to a heat-dissipating metal substrate or metal housing, it has a low electrical resistance value without impairing the heat transfer and heat dissipation characteristics of the heat-conductive graphite sheet with high thermal conductivity, and electronic equipment and high-speed wireless communication It is an object of the present invention to provide a conductive heat conductive sheet that satisfies the high frequency characteristics of the apparatus.

  In order to achieve the above object, the present invention provides, for example, a slit having a high thermal conductivity of about 700 W / mK and a crystal structure having a highly oriented crystal structure and a thermal conductive graphite sheet penetrating the thermal conductive graphite sheet. And a heat conductive sheet having a structure in which a conductor is disposed on the entire surface of the heat conductive graphite sheet including the inner surface of the slit that penetrates the semiconductor device in the electronic device / high-speed wireless communication device and dissipates heat. When sandwiched between conductive metal substrates, the heat of a semiconductor device that generates high heat is transferred to the entire conductive heat conductive sheet with high thermal conductivity, and the heat radiating substrate or housing is passed through the conductive heat conductive sheet. While radiating heat to the body, the resistance value between the semiconductor device having a metal substrate such as an electrical ground on the contact surface with the conductive heat conductive sheet and the heat radiating metal substrate or metal casing was penetrated. The conductor placed on the entire surface of the thermally conductive graphite sheet including the inner surface of the lit can be lowered, and has a low electrical resistance value without impairing the heat transfer and heat dissipation characteristics of the conductive heat conductive sheet. The effect of satisfying the high frequency characteristics of the device / high-speed communication device can be obtained.

  In addition, by placing the slit that penetrates the heat conductive graphite sheet in the longitudinal direction of the surface of the heat conductive graphite sheet, when sandwiched between the semiconductor device in the electronic equipment / high-speed communication device and the heat dissipating metal substrate, The heat of semiconductor devices that generate high heat is not easily blocked by slits that penetrate the heat conductive graphite sheet, and heat is efficiently transferred to the entire conductive heat conductive sheet with high thermal conductivity. Thus, the effect of radiating heat to the heat dissipating metal substrate or the housing through the conductive heat conductive sheet can be obtained.

  In addition, when slits that penetrate the heat conductive graphite sheet are arranged radially from the central part to the peripheral part, they are sandwiched between the semiconductor device in the electronic device / high-speed wireless communication device and the heat-dissipating metal substrate In addition, it is possible to efficiently transfer the heat of a semiconductor device having a heat spot locally and generating high heat to the entire conductive heat conductive sheet with high thermal conductivity. The effect of radiating heat to the heat dissipating metal substrate or the housing is obtained.

  Furthermore, as a conductor, any one of Au, Ag, Cu, Ni, or a composite of these metals is a conductive heat conductive graphite sheet formed by sputtering, vapor deposition, or plating. When conductive graphite sheet is sandwiched between semiconductor device and heat radiator in electronic equipment / high-speed communication device, metal conductivity with low electrical resistance value placed on the entire surface of the thermally conductive graphite sheet including the inner surface of the slit. The body makes it possible to further reduce the electrical resistance value between the semiconductor device having a terminal electrode such as an electrical ground on the contact surface with the conductive heat conductive sheet and the heat dissipating metal substrate or metal housing. The effect of satisfying the high frequency characteristics of the electronic device / high-speed communication device can be obtained without impairing the heat transfer and heat dissipation characteristics of the conductive graphite sheet.

  The present invention includes, for example, a slit that penetrates the thermally conductive graphite sheet on a highly oriented thermally conductive graphite sheet having a high thermal conductivity of about 700 W / mK, and includes an inner surface of the slit that penetrates. A conductive heat conductive sheet with a conductor placed on the entire surface of a heat conductive graphite sheet, which generates high heat when sandwiched between a semiconductor device in an electronic device / high-speed wireless communication device and a heat-dissipating metal substrate. Heat can be transferred to the entire conductive heat conductive sheet with high thermal conductivity, and heat can be dissipated through the conductive heat conductive sheet to the heat-dissipating metal substrate and housing. By having a low electrical resistance value without damaging the characteristics, the distortion characteristics of high-frequency FET semiconductor devices in high-speed wireless communication devices and the like are improved, the amplification gain is increased, and the vias are increased. Voltage - due improved drain current characteristics, the oscillation phenomenon without an effect that can satisfy the low-frequency to high-frequency characteristics of the electronic devices and high-speed wireless communications device.

  Embodiments of the present invention will be described below with reference to the drawings.

  FIG. 1 is a plan view of a conductive heat conductive sheet 2 provided with a through slit 1 according to Embodiment 1 of the present invention.

  FIG. 2 is a partially enlarged view of the through slit 1 of the thermally conductive graphite sheet 3 provided with the through slit 1 in the first and second embodiments of the present invention.

  FIG. 3 is a partially enlarged view of the slit 1 showing a state in which the conductor 4 is arranged on the entire surface of the thermally conductive graphite sheet 3 including the inner surface of the through slit 1 in the first and second embodiments of the present invention.

  FIG. 4 is a plan view of the conductive heat conductive sheet 2 provided with slits penetrating the heat conductive graphite sheet 3 as radial slits 5 from the vicinity of the central portion toward the peripheral portion.

(Embodiment 1)
First, an organic polymer film such as a polyimide film is pyrolyzed in a reducing or neutral atmosphere to produce a graphite sheet having excellent crystal orientation and high thermal conductivity. The graphite sheet had a thermal conductivity of 700 W / mK and a resistance value of about 1.5Ω.

  Next, as shown in FIGS. 1 to 3, the thermally conductive graphite sheet 3 having a high crystal orientation and a high thermal conductivity is punched into the outer shape by die punching, and at the same time, the thermally conductive graphite sheet 3 is formed. The penetrating slit 1 is formed in the longitudinal direction of the sheet. Furthermore, Cu is vacuum-deposited on the entire surface of the thermally conductive graphite sheet 3 including the inner surface of the slit 1 penetrating the front and back surfaces of the thermally conductive graphite sheet 3 one by one using, for example, a normal vacuum deposition apparatus. Thus, the conductor 4 is deposited on the entire surface of the heat conductive graphite sheet 3.

  When the heat conductivity and resistance value of the conductive heat conductive sheet 2 having the structure in which the conductor 4 is arranged are measured, the heat conductivity is 650 W / mK, which is almost the same as the heat conductivity before Cu deposition, and the resistance value. Also, an extremely low electric resistance value of about 0.1Ω was obtained.

  When this conductive heat conductive sheet 2 is used for heat dissipation of the semiconductor device of the high-speed wireless communication apparatus, the distortion characteristic in the transmission signal is better than when a conventional heat conductive graphite sheet not forming a conductor is used. In addition, the increase in amplification gain and the improvement in the bias voltage-drain current characteristics have prevented the oscillation phenomenon and satisfied the low frequency to high frequency characteristics of the electronic equipment / high-speed wireless communication device.

(Embodiment 2)
A conductive heat conductive sheet 2 as shown in FIG. 4 is produced in the same manner as in the first embodiment except that the through slits are arranged radially from the central part to the peripheral part of the heat conductive graphite sheet 3.

  This conductive heat conductive sheet 2 had a thermal conductivity of about 680 W / mK and an electric resistance value of about 0.2Ω.

  When this conductive heat conductive sheet 2 is used for heat dissipation of the semiconductor device of the high-speed wireless communication apparatus as in the first embodiment, there is no oscillation phenomenon as in the first embodiment, and there is no oscillation phenomenon in the electronic equipment / high-speed wireless communication apparatus. Low frequency to high frequency characteristics could be satisfied.

  In the first and second embodiments, Cu is used to form the conductor 4 by vapor deposition, but the conductor 4 is not only Cu but also a single metal such as Au, Ag, Ni, or a composite of these metals. The same effect can be obtained by forming by vapor deposition.

  Furthermore, as a method of forming the conductor 4, even when sputtering or plating processing is used in addition to vapor deposition, it is possible to obtain a low electric resistance value characteristic while ensuring the high heat conduction characteristic of the heat conductive graphite sheet. .

  In the first and second embodiments, a high thermal conductivity graphite sheet with high crystal orientation is used. However, the present invention is not limited to this. For example, even when a graphite sheet made of expanded graphite made from natural graphite is used, heat conduction is performed. Although the rate is inferior, the resistance can be reduced as well.

  The conductive heat conductive sheet according to the present invention has a configuration in which a slit penetrating the heat conductive graphite sheet is disposed and a conductor is disposed on the entire surface of the heat conductive graphite sheet including the inner surface of the slit. Thus, it is a conductive heat conductive sheet having a low resistance value without impairing high thermal conductivity, and is useful for applications such as heat dissipation of semiconductor devices of electronic devices and high-speed wireless communication devices.

The top view of the electroconductive heat conductive sheet in Embodiment 1 of this invention Partial enlarged view of the through slit Partial enlarged view of the through slit in which a conductor is arranged on the entire surface of the thermally conductive graphite sheet including the inner surface of the through slit. The top view of the electroconductive heat conductive sheet in Embodiment 2 of this invention Plan view of conventional thermal conductive sheet The front view which shows the use condition of the conventional heat conductive sheet

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Through slit 2 Conductive heat conductive sheet 3 Thermal conductive graphite sheet 4 Conductor 5 Radial slit 6 Thermal conductive sheet 7 Notch for fixing screw 8 Heat radiation metal substrate 9 Fixing screw 10 Metal substrate 11 Terminal 12 Semiconductor device

Claims (4)

The conductive heat conductive sheet which arranged the slit which penetrated the said heat conductive graphite sheet in the heat conductive graphite sheet, and arranged the conductor on the whole surface of the said heat conductive graphite sheet containing the said slit internal surface penetrated. The conductive heat conductive sheet according to claim 1, wherein the slits penetrating the heat conductive graphite sheet are arranged in a longitudinal direction of the surface of the heat conductive graphite sheet. The conductive heat conductive sheet according to claim 1, wherein the slits penetrating the heat conductive graphite sheet are arranged radially from the vicinity of the central portion of the heat conductive graphite sheet toward the peripheral portion. The conductive heat conductive sheet according to claim 1, wherein the conductor is one of Au, Ag, Cu, and Ni, or a composite thereof formed by sputtering, vapor deposition, or plating.

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