JP6236631B2 - Manufacturing method of heat conductive sheet - Google Patents

Description

  The present invention relates to a heat conductive sheet capable of smoothly transmitting generated heat in a thickness direction while filling a relatively large gap of about 0.2 mm to 20 mm, and a method for manufacturing the same.

  In recent years, the operation speed of various electronic devices has been remarkably improved, and accordingly, heat generation from electronic components such as semiconductor elements has increased. On the other hand, in order to stably operate the electronic apparatus, heat is diffused or dissipated using a heat conductive sheet such as a graphite sheet for these heating elements. However, the graphite sheet is generally as thin as about 0.05 mm, and it has been difficult to function sufficiently when there is a relatively large gap between the heating element and the heat sink.

  As shown in FIG. 5, the graphite sheet has a scale-like crystal structure that spreads in a plane, has a large thermal conductivity in the plane direction (a-b axis direction in which carbon 6-membered rings are connected), The thermal conductivity in the c-axis direction, which is the vertical direction, is relatively small. Therefore, as shown in FIG. 4, a sheet in which a plurality of graphite sheets 1 are bonded and cut to improve heat conduction in the thickness direction has been proposed.

  As prior art document information related to the invention of this application, for example, Patent Document 1 is known.

JP 2006-303240 A

  However, although a conventional heat conductive sheet having a high thermal conductivity in the thickness direction can be obtained, pressurization may be required when attaching heat-generating components and heat-dissipating components such as a heat sink and a heat spreader. In this case, when a thin sheet is bonded and cut perpendicularly to the bonding surface, the pressing force also acts in the direction in which the bonding surface falls. As a result, it may peel off between the bonding surface and the graphite sheet. Moreover, since the process of cutting after laminating increases, it has become a factor of cost increase. Further, in the above heat conductive sheet, heat is hardly conducted only in one direction where the graphite sheet is facing, so that the thermal conductivity in the surface direction is inferior.

The present invention solves such problems, and provides a method for producing a heat conductive sheet that has a desired thickness, a high thermal conductivity in the thickness direction and in the surface direction, and excellent mechanical strength. Objective.

In order to solve the above problems, the present invention provides a plurality of B-stage resin sheets that are parallel to each other.
Forming the slit, passing the graphite sheet through the slit so as to sew the resin sheet, and integrating the resin sheet and the graphite sheet by heat-treating and curing the resin sheet; It is equipped with.

  By comprising as mentioned above, desired thickness is obtained, the heat conductivity of thickness direction and a surface direction is high, and the heat conductive sheet excellent in mechanical strength can be obtained.

Sectional drawing of the heat conductive sheet in one embodiment of this invention The figure explaining the manufacturing method of the heat conductive sheet in one embodiment of this invention The figure explaining the manufacturing method of another heat conductive sheet in one embodiment of this invention A perspective view of a conventional heat conductive sheet Diagram showing the general graphite crystal structure

  Hereinafter, the heat conductive sheet in one embodiment of the present invention is explained, referring to drawings.

  FIG. 1 is a cross-sectional view of a heat conductive sheet 11 according to an embodiment of the present invention, in which a graphite sheet 12 is deformed to form a plurality of recesses 13, and silicone is formed in the recesses 13 on the first surface 12a side. The resin layer 14 is provided by pouring, the resin layer 14 is also provided in the concave portion 13 on the second surface 12b side opposite to the first surface 12a, and the graphite sheet 12 and the resin layer 14 are adhered to each other to form a heat. A conductive sheet 11 is configured.

  The graphite sheet 12 is a pyrolytic graphite sheet having a thickness of about 0.05 mm, and the thermal conductivity in the thickness direction is about 1300 W / m · K. This is deformed into a waveform so as to have a height of about 0.5 mm, and the recess 13 is formed. Silicone is injected into the concave portion 13 on the first surface 12 a side and the concave portion 13 on the second surface 12 b side of the graphite sheet 12 to cure, thereby forming a resin layer 14. Thus, the thickness of the heat conductive sheet 11 is about 0.5 mm.

  Here, when the second surface 12 b of the graphite sheet 12 is turned down, the maximum height H <b> 1 on the first surface 12 a side of the graphite sheet 12 is set higher than the height H <b> 2 of the resin layer 14. With this configuration, when the first surface 12a side of the graphite sheet is brought into contact with the heat generating component, the heat from the heat generating component is closest to the peak on the first surface 12a side of the graphite sheet. It becomes easy to be transmitted to the sheet 12. Since the graphite sheet 12 has a very high thermal conductivity in the surface direction, the heat from the heat-generating component spreads quickly throughout. Therefore, even if the thickness of the heat conductive sheet 11 is increased to about 0.5 mm, the heat conductivity from one surface side to the other surface side can be increased.

  In addition, it is desirable to provide the protective layer 15 on at least one surface of the sheet constituted by the graphite sheet 12 and the resin layer 14 and more desirably on both surfaces. By doing in this way, while protecting the graphite sheet 12 from external force, it becomes easy to maintain the shape of the heat conductive sheet 11. As the protective layer 15, for example, a sheet having a thickness of about 10 μm in which an acrylic adhesive layer is provided on a sheet made of polyethylene terephthalate can be used. By sticking the protective layer 15 in this manner, the thermal conductivity is somewhat deteriorated, but the height of the resin layer 14 is lower than the maximum height on the first surface 12a side of the graphite sheet, so the protective layer 15 Heat is rapidly transferred to the graphite sheet 12 to minimize the deterioration of the thermal conductivity.

  Further, the protective layer 15 may be a double-sided tape. By doing in this way, the heat conductive sheet 11 can be stably thermally connected to a heat-emitting component or a heat radiating member.

  Next, the manufacturing method of the heat conductive sheet in one embodiment of this invention is demonstrated.

  First, the graphite sheet 12 is deformed into a waveform by overlapping the graphite sheet on the forming table 20 formed in a waveform as shown in FIG. The upper surface of the graphite sheet 12 at this time is defined as a first surface 12a. Since the graphite sheet 12 has a waveform, the recesses 13 are periodically formed. Here, as the graphite sheet 12, a pyrolytic graphite sheet having a thickness of about 0.05 mm is used. The waveform height of the forming table 20 is about 0.5 mm.

  Next, as shown in FIG. 2B, the first resin 16 is injected into the concave portion 13 of the first surface 12 a of the graphite sheet using the squeegee 21. As the first resin 16, for example, thermosetting silicone is used. The first resin 16 is injected to such an extent that the recess 13 is almost filled. Thereafter, the first resin 16 is cured by being put in a dryer at about 150 ° C., and adhered to the graphite sheet 12.

  Next, as shown in FIG. 2C, the second resin 17 is placed in the concave portion 13 of the second surface 12 b opposite to the first surface 12 a using the squeegee 21 with the first surface 12 a side of the graphite sheet facing down. Inject. The second resin 17 may be the same resin as the first resin 16. Thereafter, the second resin 17 is cured by being put in a dryer at about 150 ° C., and adhered to the graphite sheet 12.

  In this way, a heat conductive sheet 11 having a thickness of about 0.5 mm as shown in FIG. By using a thermosetting resin for the first resin 16 and the second resin 17, shrinkage occurs at the time of curing, and the height H2 of the first resin 16 with the second surface 12b facing down is set to the first of the graphite sheet. The heat conductive sheet 11 made lower than the maximum height H1 on the first surface 12a side can be obtained.

  Further, as shown in FIG. 2E, it is desirable to provide a protective layer 15 on at least one surface, more preferably on both surfaces. By doing in this way, while protecting the graphite sheet 12 from external force, it becomes easy to maintain the shape of the heat conductive sheet 11. As the protective layer 15, for example, a sheet having a thickness of about 10 μm in which an acrylic adhesive layer is provided on a sheet made of polyethylene terephthalate can be used. By sticking the protective layer 15 in this way, the thermal conductivity is slightly deteriorated, but the height of the first resin 16 is made lower than the maximum height on the first surface 12a side of the graphite sheet. Heat is quickly transferred from the layer 15 to the graphite sheet 12, and deterioration of thermal conductivity can be minimized.

  Next, the manufacturing method of another heat conductive sheet in one embodiment of the present invention is explained.

  First, as shown in FIG. 3A, a plurality of slits 19 parallel to each other are formed in a B-stage-shaped resin sheet 18 having a thickness of about 0.5 mm. The resin sheet 18 is made of thermosetting silicone, and the width of the slits 19 is about 0.1 mm, and the interval between the slits 19 is about 0.5 mm.

  Next, as shown in FIG. 3B, the graphite sheets 12 are passed through the slits 19 so as to sew the resin sheets 18 so that the graphite sheets 12 are alternately above and below the resin sheets 18. Here, as the graphite sheet 12, a pyrolytic graphite sheet having a thickness of about 0.05 mm is used. Thereafter, the resin sheet 18 is cured by being put in a drier at about 150 ° C. and bonded to the graphite sheet 12. Since the graphite sheet 12 is alternately placed above and below the resin sheet 18, the height of the resin sheet 18 can be made lower than the maximum height of the graphite sheet 12 even after curing, and the thermal resistance with the heat-generating component or the like is reduced. Can do.

  Further, as shown in FIG. 3C, it is desirable to provide a protective layer 15 on at least one surface, more preferably on both surfaces. By doing in this way, while protecting the graphite sheet 12 from external force, it becomes easy to maintain the shape of the heat conductive sheet 11. As the protective layer 15, for example, a sheet having a thickness of about 10 μm in which an acrylic adhesive layer is provided on a sheet made of polyethylene terephthalate can be used. By sticking the protective layer 15 in this manner, the thermal conductivity is slightly deteriorated, but the height H2 of the resin sheet 18 is lower than the maximum height H1 on the first surface 12a side of the graphite sheet. Heat is quickly transferred from the protective layer 15 to the graphite sheet 12, and deterioration of thermal conductivity can be minimized.

  The heat conductive sheet of the present invention has a desired thickness and has a high thermal conductivity in the thickness direction, which is industrially useful.

11 Thermal Conductive Sheet 12 Graphite Sheet 12a First Surface 12b Second Surface 13 Recess 14 Resin Layer 15 Protective Layer 16 First Resin 17 Second Resin 18 Resin Sheet 19 Slit 20 Molding Base 21 Squeegee

Claims (2)

Forming a plurality of parallel slits in a B-stage-shaped resin sheet; passing a graphite sheet through the slit so as to sew the resin sheet; and curing the resin sheet by heat treatment The manufacturing method of the heat conductive sheet provided with the process of integrating a sheet | seat and the said graphite sheet. The manufacturing method of the heat conductive sheet of Claim 1 which has the process of providing a protective layer in the at least one surface of the said heat conductive sheet.

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