Heat dissipation sheet, manufacturing method of heat dissipation sheet, and electronic apparatus
A heat dissipation sheet includes a first sheet composed of a plurality of first carbon nanotubes, and a second sheet composed of a plurality of second carbon nanotubes, wherein the first sheet and the second sheet are coupled in a stacked state, and the first carbon nanotubes and the second carbon nanotubes are different in an amount of deformation when pressure is applied.
1. A heat dissipation sheet comprising:
a first sheet composed of a plurality of first carbon nanotubes, the first sheet being configured as a heat dissipation layer; and
a second sheet composed of a plurality of second carbon nanotubes, the second sheet being configured as a tight contact layer, deformation of the tight contact layer being for following deformation of a heat generation source,
the first sheet and the second sheet are coupled in a stacked state,
the first carbon nanotubes and the second carbon nanotubes are different in an amount of deformation when first pressure to the first carbon nanotubes is applied and second pressure to the second nanotubes is applied, the first pressure being equal to the second pressure,
a first amount of deformation that is an amount of deformation when the first pressure to the first carbon nanotubes is applied is an amount of deformation of several percentages with respect to a length before pressure is applied, and
a second amount of deformation that is an amount of deformation when the second pressure to the second carbon nanotubes is applied is an amount of deformation of several tens of percentages with respect to a length before pressure is applied.
2. The heat dissipation sheet according to claim 1 , wherein the first sheet and the second sheet are coupled by a resin.
3. The heat dissipation sheet according to claim 1 , wherein thermal conductivity of the first carbon nanotubes is higher than thermal conductivity of the second carbon nanotubes.
4. The heat dissipation sheet according to claim 1 , wherein a G/D ratio of the first carbon nanotubes is higher than a G/D ratio of the second carbon nanotubes.
5. The heat dissipation sheet according to claim 1 , wherein the G/D ratio of the first carbon nanotubes is equal to or higher than 2, and the G/D ratio of the second carbon nanotubes is lower than 2.
6. The heat dissipation sheet according to claim 1 , wherein the second carbon nanotubes forming the second sheet are larger than the first carbon nanotubes forming the first sheet in the number of carbon nanotubes per unit area.
7. The heat dissipation sheet according to claim 1 , wherein
an area occupancy rate of the first carbon nanotubes forming the first sheet in a sheet surface is 1% to 5%, and
an area occupancy rate of the second carbon nanotubes forming the second sheet in a sheet surface is 2% to 15%.
8. The heat dissipation sheet according to claim 1 , wherein length of the first carbon nanotubes forming the first sheet is longer than length of the second carbon nanotubes forming the second sheet.
9. The heat dissipation sheet according to claim 1 , wherein
the length of the first carbon nanotubes forming the first sheet is 100 to 500 μm, and
the length of the second carbon nanotubes forming the second sheet is 20 to 200 μm.
10. The heat dissipation sheet according to claim 1 , further comprising:
a third sheet composed of a plurality of third carbon nanotubes, wherein
the third sheet is coupled in a state of being stacked on an opposite side to the second sheet across the first sheet, and
the second carbon nanotubes and the third carbon nanotubes are larger than the first carbon nanotubes in the amount of deformation when pressure is applied.
11. The heat dissipation sheet according to claim 1 , further comprising:
a third sheet composed of a plurality of fourth carbon nanotubes, wherein
the third sheet is coupled in a state of being stacked on an opposite side to the second sheet across the first sheet, and
the fourth carbon nanotubes are identical to the first carbon nanotubes in the amount of deformation when pressure is applied.
12. The heat dissipation sheet according to claim 1 , wherein
the first sheet is generated by performing a high-temperature treatment, and
the second sheet is generated by densifying the a plurality of second carbon nanotubes that is not performed the high-temperature treatment.
13. An electronic apparatus comprising:
a semiconductor chip;
a heat dissipation sheet thermally connected to the semiconductor chip; and
a heat spreader thermally connected to the heat dissipation sheet,
the heat dissipation sheet includes
a first sheet composed of a plurality of first carbon nanotubes, the first sheet being configured as a heat dissipation layer, and
a second sheet composed of a plurality of second carbon nanotubes, the second sheet being configured as a tight contact layer, deformation of the tight contact layer being for following deformation of the semiconductor chip,
the first sheet and the second sheet are coupled in a stacked state, and
the first carbon nanotubes and the second carbon nanotubes are different in an amount of deformation when first pressure to the first carbon nanotubes is applied, the first pressure being equal to the second pressure,
a first amount of deformation that is an amount of deformation when the first pressure to the first carbon nanotubes is applied is an amount of deformation of several percentages with respect to a length before pressure is applied, and
a second amount of deformation that is an amount of deformation when the second pressure to the second carbon nanotubes is applied is an amount of deformation of several tens of percentages with respect to a length before pressure is applied.
14. The electronic apparatus according to claim 13 , wherein
the second carbon nanotubes are larger than the first carbon nanotubes in the amount of deformation when pressure is applied, and
the second sheet is set to exist on a side of the semiconductor chip.
15. The electronic apparatus according to claim 14 , wherein
the heat dissipation sheet includes a third sheet composed of a plurality of third carbon nanotubes,
the third sheet is coupled in a state of being stacked on an opposite side to the second sheet across the first sheet,
the third carbon nanotubes are larger than the first carbon nanotubes in the amount of deformation when pressure is applied, and
the third sheet is set to exist on a side of the heat spreader.