JP7024377B2 - Heat dissipation sheet and its manufacturing method and how to use the heat dissipation sheet - Google Patents

Description

The present invention is interposed between a high heat generating component such as a CPU (Central Processing Unit), a transistor, a light emitting diode (LED) or a power control element, and a heat dissipation cooling member such as a heat sink, a housing or a wiring board. The present invention relates to a heat-dissipating sheet for forming a good thermal bond between the two, a method for manufacturing the heat-dissipating sheet, and a method for using the heat-dissipating sheet.

Thermal Interface Materials (hereinafter referred to as "TIM") such as heat-dissipating grease and heat-dissipating sheets that are interposed between high-heat-generating parts such as power control elements and heat-dissipating cooling members (radiators) to assist heat conduction between the two. There is), for example, a sheet-like or liquid organic compound or the like in which a powder filler (thermally conductive particles) having a high thermal conductivity is dispersed. For example, thermal grease includes oils such as polyα-olefin oil and silicone oil, and as heat conductive particles, metals such as silver or aluminum, metal oxides such as zinc oxide or aluminum oxide, or inorganic substances such as boron nitride or aluminum nitride. Those in which nitrides and the like are dispersed are known. The heat dissipation sheet includes, for example, an organic resin compound such as silicone resin, a metal such as silver or aluminum as heat conductive particles, a metal oxide such as zinc oxide or aluminum oxide, or an inorganic nitride such as boron nitride or aluminum nitride. It is known that objects and the like are dispersed and formed into a sheet.

In recent years, as a result of high-power operation of electric power control equipment and high-speed operation of electronic equipment, the amount of heat generated from the equipment tends to increase. On the other hand, with the miniaturization of equipment and the high-density mounting of heat-generating devices, the heat-generating density also tends to increase. In response to such an increase in the amount of heat generation and the increase in density, in order to maintain the performance of the equipment stably for a long period of time, it is necessary to efficiently remove the heat generation in the equipment, so it is a highly heat-generating component. It is required to form a TIM layer with a radiator having a lower thermal resistance than before.

Liquid TIM represented by thermal paste can be automatically applied to highly heat-generating parts and heat-dissipating cooling members by dripping or printing. However, the thermal paste may gradually deteriorate due to the sedimentation and deposition of the heat conductive particles and the chemical change of the oil agent due to the surface activity of the heat conductive particles. Regarding the storage of goods, it is necessary to manage the deadline for a relatively short period of time. Further, if the content of the heat conductive particles in the heat radiation grease is increased in order to increase the heat conductivity, the fluidity of the heat radiation grease may be lost, and automatic coating may be difficult. Furthermore, if the fluidity of the heat-dissipating grease is lost, it becomes difficult to discharge excess liquid TIM from between the high heat-generating components and the radiator when they are pressed against each other through the applied liquid TIM. Therefore, a thick TIM layer may be formed and the thermal resistance between the high heat generating component and the radiator may increase. In addition, if the fluidity of the thermal paste is lost, the thermal paste may enter the microscopic irregularities on the surface of the heat-generating component or the surface of the radiator, making it difficult to adhere to the heat-dissipating grease. There is a risk that the thermal resistance at the interface with the surface of the sex component or the surface of the radiator will increase.

On the other hand, the sheet-shaped TIM represented by the heat-dissipating sheet can be stored for a relatively long period of time by having a large-sized shape. In addition, if a small piece of sheet-shaped TIM cut to an appropriate size is placed, a certain amount of sheet-shaped TIM can be supplied between the high heat-generating component and the radiator, so it is easy to handle manually. Highly adaptable to small-lot, high-mix production. However, in the sheet-shaped TIM, air bubbles are likely to intervene between the surface of the sheet and the surface of the high heat generating component or the surface of the radiator, and the air bubbles at the interface between the TIM and the surface of the high heat generating component or the surface of the radiator. As the contact area decreases, the thermal resistance at these interfaces may increase. In particular, when the gap between the high heat generating component and the radiator fluctuates greatly depending on the location, it may be difficult for the sheet-shaped TIM to follow the change in the size of the gap, and it may be liquid. Since it may be difficult to fill the gap with the liquid TIM due to the movement of the liquid TIM from the portion having a small gap to the portion having a large gap as in the case of TIM, bubbles are particularly likely to remain.

Unlike liquid TIM, which requires ensuring fluidity, sheet-shaped TIM can contain a relatively large amount of thermally conductive particles, so it is possible to obtain higher thermal conductivity than liquid TIM. be. However, if the sheet-shaped TIM contains a larger amount of thermally conductive particles for the purpose of obtaining higher thermal conductivity, the flexibility of the sheet is lost, and the surface of the high heat generating component or the surface of the radiator is macroscopic. Since it may be difficult to make close contact due to deformation following unevenness or curvature, thermal resistance may increase at the interface with the surface of these members. Further, since the sheet-shaped TIM does not have the fluidity of the liquid TIM, it may be more difficult to follow and adhere to the microscopic irregularities on the surface of these members.

A phase change sheet is known as a technique that combines the ease of handling of a sheet-shaped TIM with the ability of a liquid TIM to follow a non-smooth surface or a non-flat surface. Examples of the phase change sheet include a material such as paraffin that softens and flows at a high temperature and contains thermally conductive particles. Since it is a sheet-like solid substance near room temperature, it can be easily attached in small pieces and has excellent storage stability. Then, after interposing between the high heat generating component and the radiator, the phase change sheet is heated and softened to promote the flow, thereby filling the space between the high heat generating component and the radiator. It is possible.

However, since the phase change sheet is a sheet-like TIM near room temperature, it is said that air bubbles are likely to intervene when the phase change sheet is mounted between a heat-generating component and a radiator at room temperature, for example. The problem has not been resolved. In addition, once the bubbles are formed, they are not easily discharged only by fluidizing the phase change sheet at high temperature, so the contact area between the TIM and the surface of the high heat generating component or the surface of the radiator is reduced by the bubbles. Therefore, it is difficult to solve the problem that the thermal resistance at the interface with the surface of these members increases.

Further, if the content of the heat conductive particles is increased in order to increase the heat conductivity of the phase change sheet, it may be difficult to secure the fluidity at the time of melting. For this reason, the problem that the adhesion to the surface of the high heat generating component and the surface of the radiator is lowered and the heat transfer is rather hindered is caused by increasing the content of the heat conductive particles in the thermal paste. It is exactly the same as the harmful effect, and it is difficult to solve it.

In the sheet-shaped TIM, an attempt to prevent the mixing of air bubbles by setting the viscosity of the pressure-sensitive adhesive layer to be small to obtain a large adhesive area and adhesive strength is disclosed in, for example, Patent Document 1. According to Patent Document 1, the loss elastic modulus G "at 50 ° C. of the pressure-sensitive adhesive layer heated by the heat of the adherend is 5 × 105 Pa or less, so that the pressure-sensitive adhesive layer on the surface of the heating element or the heat radiator As a result, the contact area between the heat conductive pressure-sensitive adhesive sheet and the adherend can be sufficiently secured, so that the contact heat resistance can be reduced.

Further, for example, in Patent Document 2, since the pressure-sensitive adhesive layer has a center line average surface roughness of 0.1 to 1.0 μm, it is possible to prevent bubbles from remaining at the interface with the adherend, and also , A thin adhesive sheet having excellent adhesive strength is disclosed.

Thermally conductive sheets using a porous body are proposed, for example, in Patent Documents 3 to 5. Patent Document 3 discloses a heat-dissipating material characterized by containing a heat-dissipating material made of silicon carbide in a bubble film of a foam made of a polyolefin-based resin having open cells. This heat-dissipating material can be produced by heating and kneading a resin, a heat-dissipating material, and a foaming agent, forming a sheet by press molding, and heating the sheet at a higher temperature.

Further, Patent Document 4 discloses a heat conductive material, which comprises at least a foamable high heat conductive layer formed of a resin composition containing a foaming agent that foams at 40 ° C. or higher and a high heat conductive filler. Has been done. This heat conductive material is prepared by mixing an acrylic polymer, a heat conductive filler, a foaming agent, etc. in a solvent to prepare a coating solution, then applying the coating solution on a substrate and heating and drying. Can be manufactured.

Further, Patent Document 5 discloses a heat-dissipating sheet characterized in that a heat-dissipating material made of a heat-dissipating gel or heat-dissipating grease is impregnated into a heat-dissipating base material having open cells to form a spongy heat-dissipating body. This heat dissipation sheet can be produced by impregnating a urethane foam with a silicone compounding agent (for example, a thermosetting silicone resin and a thermosetting filler) and then heat-curing the silicone compounding agent.

The heat radiating sheet having surface adhesiveness is not limited to a single structure, and a heat conductive sheet in which a plurality of materials are laminated and composited is known. For example, in Patent Document 6, a laminated structure of a metal foil and a heat-dissipating silicone sheet having a specific hardness is used, in Patent Document 7, a heat-dissipating sheet having a specific hardness compounded with a metal mesh or the like is used, and in Patent Document 8, a heat-dissipating sheet having a high thermal conductivity is used. A cooling structure for a semiconductor device using a heat transferable sheet provided with a metal wire net is disclosed. These configurations are intended for high thermal conductivity, and a metal foil or a metal mesh having high rigidity is compounded with a thermal conductive sheet. Further, Patent Document 9 discloses a high thermal conductive electromagnetic wave shielding sheet having a structure in which a silicone rubber layer and a graphite film are laminated. Further, Patent Document 10 discloses a high thermal conductive electromagnetic wave shielding sheet having a structure in which a silicone rubber layer and a conductive fiber such as carbon fiber or metal-coated fiber are laminated. Further, in Patent Document 11, a metal foil having a predetermined thickness is used as a heat radiating body, and a heat conductive adhesive layer is formed on one side of the metal foil to form a heat radiating body and a heat conductive pressure-sensitive adhesive sheet. A heat conductive pressure-sensitive adhesive sheet with a metal foil integrally formed is disclosed.

With the heat radiating sheet alone, it may be difficult to follow the macroscopic unevenness or curvature of the surface of the member and to adhere to it. In this case, it has been conventionally practiced to improve the adhesion while maintaining the thermal conductivity by interposing a thermal grease layer in which the thermal conductive particles are blended between the heat radiating sheet and the member. However, if a high-viscosity heat-dissipating grease containing heat-conducting particles is applied to the surface of the heat-dissipating sheet, a thick TIM layer is formed as a whole and the thermal resistance increases. A typical example of an application in which a thickening of the TIM layer can be tolerated is an application whose main purpose is to secure a certain level of electrical dielectric strength by maintaining a certain level of gap with a heat dissipation sheet, and to have a high degree of heat. The purpose is not to obtain conductivity.

As mentioned above, when trying to introduce a TIM with high thermal conductivity between a high heat generating component and a radiator, a large amount of thermally conductive particles are contained in both liquid TIM and sheet-shaped TIM. As a result, there is a problem that heat transfer is hindered due to a decrease in adhesion or a mixture of air bubbles.

International Publication No. 2011/145523 Japanese Unexamined Patent Publication No. 2016-155950 Japanese Unexamined Patent Publication No. 10-72534 JP-A-2002-317046 Japanese Patent Application Laid-Open No. 2003-31980 Japanese Unexamined Patent Publication No. 6-291226 Japanese Unexamined Patent Publication No. 7-14950 Japanese Unexamined Patent Publication No. 9-5456 Japanese Unexamined Patent Publication No. 11-340673 Japanese Unexamined Patent Publication No. 11-317592 Japanese Unexamined Patent Publication No. 11-186473

In view of the above problems, it is an object of the present invention to provide a heat radiating sheet capable of ensuring good thermal conductivity between a high heat generating component and a heat radiating cooling member, a method for manufacturing the heat radiating sheet, and a method for using the heat radiating sheet. And.

In order to solve the above problems, the heat radiating sheet of the present invention contains, in order, a resin composition containing heat conductive particles and swelling with an organic solvent, and has a first elastic body layer having adhesiveness and heat conductivity. The first elastic body is provided with a laminate in which a support layer having a support layer and a second elastic body layer containing a heat conductive particle and swelling with an organic solvent and having adhesiveness are laminated. The organic solvent is contained in at least one of the layer and the second elastic body layer, and the ratios of the organic solvent and the resin composition in the first elastic body layer and the second elastic body layer are independently mass ratios. It is 0: 1 to 1: 8.

The thickness of the first elastic body layer and the second elastic body layer may be independently 10 μm to 20 μm, respectively.

Further, in order to solve the above-mentioned problems, the method for producing a heat-dissipating sheet of the present invention is a method for manufacturing the heat-dissipating sheet, in which a resin composition containing heat-conducting particles and swelling with an organic solvent is prepared in order. A second elastic body containing a first elastic body layer having adhesiveness, a support layer having thermal conductivity, and a resin composition containing thermally conductive particles and swelling with an organic solvent, and having adhesiveness. The swelling step of swelling the first elastic body layer and / or the second elastic body layer of the laminated body in which the layer and the layer are laminated with the organic solvent is included, and in the swelling step, the organic solvent and the first. The ratio of the resin composition of the elastic layer and the ratio of the organic solvent to the resin composition of the second elastic layer are independently 0: 1 to 1: 1 in terms of mass ratio.

Prior to the swelling step, a radiation irradiation step of irradiating the first elastic body layer and / or the second elastic body layer with radiation may be included.

The radiation may be an electron beam or a gamma ray.

Further, in order to solve the above problems, the method of using the heat radiating sheet of the present invention, in order, contains a resin composition containing thermally conductive particles and swelling with an organic solvent, and has an adhesive first elastic body layer. The above-mentioned laminated body in which a support layer having thermal conductivity and a second elastic body layer containing a resin composition containing thermally conductive particles and swelling with an organic solvent and having adhesiveness are laminated. The swelling includes a swelling step of swelling the first elastic body layer and / or the second elastic body layer with the organic solvent, and a crimping step of crimping the heat radiating sheet to the adherend after the swelling step. In the step, the ratio of the organic solvent to the resin composition of the first elastic body layer and the ratio of the organic solvent to the resin composition of the second elastic body layer are independently 0: It is 1 to 1: 1.

INDUSTRIAL APPLICABILITY According to the present invention, it is possible to provide a heat radiating sheet capable of ensuring good thermal conductivity between a high heat generating component and a heat radiating cooling member, a method for manufacturing the heat radiating sheet, and a method for using the heat radiating sheet.

It is a schematic diagram which shows the cross section of the heat dissipation sheet which concerns on one Embodiment of this invention. It is a flow figure which shows an example of the manufacturing method of the heat dissipation sheet which concerns on one Embodiment of this invention. It is a flow figure which shows an example of the usage method of the heat dissipation sheet which concerns on one Embodiment of this invention. It is sectional drawing which shows the use example of the heat dissipation sheet which concerns on one Embodiment of this invention.

Hereinafter, a heat radiating sheet, a method for manufacturing the heat radiating sheet, and a method for using the heat radiating sheet according to the present invention will be described. The present invention is not limited to the following examples, and can be arbitrarily modified without departing from the gist of the present invention.

<Heat dissipation sheet>
The heat radiating sheet according to the embodiment of the present invention includes, in order, a laminated body in which a first elastic body layer, a support layer, and a second elastic body layer are laminated. That is, the support layer is between the first elastic body layer and the second elastic body layer.

(First elastic body layer)
The first elastic layer contains thermally conductive particles and contains a resin composition that swells with an organic solvent. That is, this resin composition contains thermally conductive particles. Examples of the thermally conductive particles include metal particles as having thermal conductivity, and particles such as gold, silver, and copper can be used. In particular, copper particles are preferably used because they have a high specific density that does not easily flow out from the first elastic layer, have excellent thermal conductivity, and are relatively inexpensive.

The shape of the heat conductive particles can be needle-shaped, spherical, scaly, or the like. In particular, when it is spherical, it is more preferable because a large amount of thermally conductive particles can be contained in the first elastic body layer and high thermal conductivity can be imparted.

Next, regarding the size of the thermally conductive particles, since the particles are uniformly dispersed in the first elastic body layer when the maximum particle diameter is 20 μm or less, excellent heat is maintained while maintaining the elastic performance. Conductivity can be imparted. In particular, when the maximum particle size of the heat conductive particles is 10 μm or less, the heat conductive particles having a higher concentration can be uniformly dispersed.

Further, the content of the heat conductive particles in the first elastic body layer is preferably 30% by mass to 70% by mass. With a content in this range, it becomes easy to satisfy both elastic performance and thermal conductivity. If the content is less than 30% by mass, the thermal conductivity may not be satisfied. Further, if the content is 70% by mass or more, the elasticity may not be satisfied and the adhesion may be poor. In particular, since the content is 50% by mass to 70% by mass, bubbles are mixed at the close contact interface with the highly heat-generating component to be an adherend and the heat-dissipating cooling member while containing a large amount of thermally conductive particles. The first elastic body layer can be obtained by preventing the above-mentioned problems and satisfying the adhesion with the adherend.

Next, the first elastic body layer has adhesiveness. As a result, it is possible to make good adhesion to the adherend. Adhesiveness can be imparted by including a resin composition in which the first elastic body layer has adhesiveness (hereinafter, may be referred to as "adhesive resin composition"). The adhesive resin composition is not particularly limited as long as it has a surface tack in the state of a dry coating film, and examples thereof include compositions containing ethyl cellulose, methyl cellulose, polyvinyl alcohol, rosin and the like as resin components. Can be done. Other adhesive resin compositions include acrylic adhesive resins, silicone adhesive resins, urethane adhesive resins, vinyl alkyl ether adhesive resins, vinylpyrrolidone adhesive resins, acrylamide adhesive resins, and cellulose. Examples thereof include a composition containing a based adhesive resin, a rubber based adhesive resin and the like as a resin component. These adhesive resin compositions may be used alone or in combination of two or more as long as the object of the present invention is not impaired. Further, the adhesive resin composition may contain a solvent, an additive or the like in addition to the resin component. Further, the adhesive resin composition may be a "resin composition containing thermally conductive particles and swelling with an organic solvent". For example, a composition in which thermally conductive particles are dispersed in the resin component exemplified above can be mentioned as an adhesive resin composition.

The content of the adhesive resin composition in the first elastic body layer is preferably 20% by mass to 50% by mass. When the content is in this range, it becomes easy to obtain a first elastic body layer which is excellent in thermal conductivity and further satisfies both elastic performance and adhesiveness. If the content is less than 20% by mass, the elastic performance may not be satisfied. Further, when the content is 50% by mass or more, the elastic performance and the adhesiveness are satisfied, but the content of the heat conductive particles is small, so that the heat conductivity may not be satisfied. In particular, when the content is 30% by mass to 40% by mass, the content of the heat conductive particles and the adhesive resin composition can be balanced, so that the heat conductive particles are contained in a large amount and the cover is covered. It is possible to prevent the mixing of air bubbles at the contact interface with the highly heat-generating component and the heat-dissipating cooling member to be the body, and to obtain the first elastic body layer that satisfies the adhesion with the adherend.

(Support layer)
Next, the support layer has thermal conductivity. Due to the presence of the support layer, for example, a large-sized heat-dissipating sheet can be obtained, and long-term storage is possible as compared with the heat-dissipating grease. Furthermore, if it is a heat dissipation sheet, it can be cut to an appropriate size and small pieces can be placed, and a certain amount of heat dissipation sheet can be supplied between the high heat generation component and the heat dissipation cooling member, so it can be handled manually. It is also easy, and it is possible to increase the adaptability to the production of a wide variety of small quantities. Further, since the heat conductive support layer is provided, heat from the high heat generating component is easily dissipated through the support layer in the direction parallel to the contact surface where the heat radiating sheet is in close contact with the high heat generating component. The effect can be expected.

As the support layer having thermal conductivity, a metal sheet-shaped one can be used, for example, a copper-containing alloy having excellent thermal conductivity such as gold, silver, copper, brass, copper containing silver, and light weight. It is possible to use a sheet of excellent aluminum and an aluminum-containing alloy or the like. In particular, a copper sheet is preferable to be used because it has excellent thermal conductivity and is relatively inexpensive.

The thickness of the support layer is not particularly limited as long as it satisfies the flexibility as a heat dissipation sheet, but generally, a support layer having a thickness of 10 μm to 50 μm is used.

(Second elastic body layer)
The second elastic layer contains thermally conductive particles, contains a resin composition that swells with an organic solvent, and has adhesiveness. The details of the second elastic body layer are the same as those of the first elastic body layer, and the description thereof will be omitted. However, the second elastic body layer can contain a material such as a heat conductive particle different from the first elastic body layer or a resin composition swelling with an organic solvent in a different content. For example, copper particles can be used for the first elastic body layer, and more silver particles than the copper particles on the left can be used for the second elastic body layer. Further, the first elastic body layer and the second elastic body layer can be the same elastic body layer.

The organic solvent is contained in at least one of the first elastic body layer and the second elastic body layer, and the ratios of the organic solvent and the resin composition in the first elastic body layer and the second elastic body layer are respectively. Independently, the mass ratio is 0: 1 to 1: 8. For example, the ratio of the organic solvent in the first elastic body layer can be set higher or lower than that of the organic solvent in the second elastic body layer, or can be set to the same ratio. That is, in consideration of the mixing of air bubbles at the adhesion interface with the adherend and the adhesion with the adherend, any organic solvent and resin are used for each of the first elastic body layer and the second elastic body layer. It can be the ratio of the composition and can be prepared in a suitable swelling state.

The resin composition may be swelled by an organic solvent, and if the surface of the first elastic body layer and / or the second elastic body layer is porous, the organic solvent easily permeates. This is preferable because the resin composition can be easily swollen. The first elastic body layer and the second elastic body layer may be a resin composition in which at least one of them is swollen with an organic solvent, and both the first and second elastic body layers are swollen with an organic solvent . The resin composition may be the same. Further, the first elastic body layer and / or the second elastic body layer may have a single layer structure having both adhesiveness and swelling property, and an adhesive layer is arranged on the surface and an organic solvent is used inside. It may have a multilayer structure in which a swelling resin composition layer is arranged.

The organic solvent that can be used is not particularly limited as long as it can swell the resin composition. Although it depends on the combination with the resin composition to be swelled, for example, ethyl acetate, butyl acetate, ethanol, ether, benzene, hexane, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol, n-butyl alcohol and the like shall be exemplified. Can be done. Further, if it is an oil agent such as silicone or α-olefin, it can be used for a long time and can maintain an elastic state for a long time because it satisfies the permeability to the porous material and is not volatile.

As described above, the elasticity of the first elastic body layer and the second elastic body layer can be adjusted by appropriately adding an organic solvent. By adjusting the elasticity to a predetermined level, it follows the unevenness of the surface to be adhered to the adherend, prevents air bubbles from entering at the adhesion interface with the adherend, and exhibits good adhesion to the adherend. be able to. As a result, good thermal conductivity can be ensured between the high heat generation component and the heat dissipation cooling member. If it is adjusted to have more appropriate elasticity, it will be easier to handle when arranging the heat dissipation sheet between the high heat generation component and the heat dissipation cooling member while satisfying the good thermal conductivity shown on the left. Relocation etc. becomes easy.

If the elasticity of the first elastic body layer and the second elastic body layer is insufficient, the adherence of the adherend to the unevenness of the contact target surface may be insufficient, and bubbles may be mixed. In addition, there is a risk that the adhesion to the adherend will not be satisfied. Further, if the elasticity is excessive, when crimping is performed between the high heat generating component and the heat dissipation cooling member, the elasticity may protrude from the space and adhere to a nearby circuit to short-circuit the circuit. be.

The thickness of the first elastic body layer and the thickness of the second elastic body layer are independently the maximum heights (R _max ) of the contact target surface in consideration of the surface roughness of the contact target surface of the adherend. ) Is set to 10 to 20 times, good adhesion can be satisfied. Specifically, when R _max is 1 μm and the thickness of the elastic body layer is 10 μm to 20 μm, the elastic body layer follows the fine irregularities on the surface of the adherend and is good with the adherend. It is possible to demonstrate good adhesion. Further, in consideration of the adhesion to the adherend, each of the first elastic body layer and the second elastic body layer can be independently set to a suitable thickness. That is, the thickness of the first elastic body layer can be made larger or smaller than the thickness of the second elastic body layer, or can be set to the same thickness.

FIG. 1 is a schematic view showing a cross section of a heat radiating sheet according to an embodiment of the present invention. The heat radiating sheet 10 has a laminated body 4 structure in which the first elastic body layer 1, the support layer 2, and the second elastic body layer 3 are laminated in this order. Although not shown in FIG. 1, the heat radiating sheet 10 facilitates cutting of the laminated body 4, the protective sheet that protects the surfaces of the first elastic body layer 1 and the second elastic body layer 3, and the heat radiating sheet 10. Perforations and the like can be provided.

The heat radiating sheet according to the embodiment of the present invention not only makes it difficult for bubbles to remain at the interface with the adherend, but also suppresses the thickness of the TIM layer and secures low thermal resistance. Further, by rearranging the surface of the heat radiating sheet and the heat conductive particles contained in the surface, it is possible to follow the unevenness of the surface to be adhered to the adherend and to secure the adhesion.

<Manufacturing method of heat dissipation sheet>
The method for manufacturing a heat dissipation sheet according to an embodiment of the present invention is, in order, the first elastic body layer and / or the first elastic body layer and / or the laminated body in which the first elastic body layer, the support layer, and the second elastic body layer are laminated. The second elastic body layer includes a swelling step of swelling with an organic solvent.

The first elastic body layer and the second elastic body layer contain heat conductive particles and contain a resin composition that swells with an organic solvent. The details of the resin composition that swells with the heat conductive particles and the organic solvent are the same as those described in the heat dissipation sheet, and the description thereof will be omitted. However, the second elastic body layer may contain a material different from that of the first elastic body layer in a different content. For example, copper particles can be used for the first elastic body layer, and more silver particles than the copper particles on the left can be used for the second elastic body layer. Further, the first elastic body layer and the second elastic body layer can be the same elastic body layer. Since the surface of the first elastic body layer and / or the second elastic body layer is porous, the organic solvent easily permeates, and the swelling of the resin composition becomes easy. Further, the first elastic body layer and / or the second elastic body layer may have a single layer structure having both adhesiveness and swelling property, and an adhesive layer is arranged on the surface and an organic solvent is used inside. It may have a multilayer structure in which a swollen body layer containing a swollen resin composition is arranged.

The organic solvent that can be used in the swelling step is not particularly limited as long as it can swell the resin composition. Although it depends on the combination with the resin composition to be swollen, for example, ethyl acetate, butyl acetate, ethanol, ether, benzene, hexane, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol, n-butyl alcohol and the like can be exemplified. I can. Further, oil agents such as silicone and α-olefin can be used.

In the swelling step, the ratio of the organic solvent to the resin composition of the first elastic body layer and the ratio of the organic solvent to the resin composition of the second elastic body layer are independently measured by mass ratio. It is 0: 1 to 1: 1. For example, the ratio of the organic solvent in the first elastic body layer can be set higher or lower than that of the organic solvent in the second elastic body layer, or can be set to the same ratio. That is, in consideration of the mixing of air bubbles at the adhesion interface with the adherend and the adhesion with the adherend, any organic solvent and resin are used for each of the first elastic body layer and the second elastic body layer. It can be the ratio of the composition and can be prepared in a suitable swelling state.

In addition, the support layer has thermal conductivity. The details of the support layer are the same as those described in the heat dissipation sheet, and the description thereof will be omitted.

Hereinafter, a method for manufacturing a heat radiating sheet according to an embodiment of the present invention will be described with reference to the flow chart shown in FIG.

(Preparation process of resin solution)
This is a step of adjusting the resin composition contained in the first elastic body layer and the second elastic body layer into a state of a resin solution in advance (FIG. 2S1). Here, the resin component is dissolved in a solvent that dissolves the resin component to obtain a resin solution. As the resin component, those described in the heat dissipation sheet may be used alone or in combination. Further, in this step, various monomers which are raw materials for the resin and a solvent can be mixed and polymerized under predetermined temperature conditions to prepare a resin component.

In the case of polymerizing the monomer, as the usable monomer, for example, methyl acrylate, ethyl acrylate, n-propyl acrylate, isopropyl acrylate, n-butyl acrylate and the like can be used.

The solvent is not particularly limited as long as it can dissolve the resin component, and is, for example, ethyl acetate, butyl acetate, ethanol, ether, benzene, hexane, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol, n-. Butyl alcohol or the like can be used.

(Preparation process of swellable resin composition)
This is a step of preparing a swellable resin composition by mixing the resin solution prepared above with at least the thermally conductive particles (FIG. 2S2). It is not always necessary if the resin component in the resin solution has adhesiveness due to having a surface tack after drying, but if the resin component does not have adhesiveness, an adhesive-imparting agent is separately added. Can be mixed. The adhesive is not particularly limited as long as it imparts adhesiveness to the elastic layer by imparting adhesiveness. For example, a rosin-based tackifier having a surface tack in a dry state, a polymerized rosin-based tackifier, a polymerized rosin ester-based tackifier, a rosinphenol-based tackifier, a terpene-based tackifier, a terpenphenol-based tackifier, and a styrene-based adhesive. A tackifier and the like can be mentioned as a tackifier. Further, in order to prepare the solid content of the swellable resin composition, a solvent such as ethyl acetate, butyl acetate, ethanol, ether, benzene, hexane, methyl ethyl ketone, methyl isobutyl ketone, isopropyl alcohol and n-butyl alcohol may be mixed. can.

Further, in the step of preparing the swellable resin composition, a foaming agent can be further mixed in order to make the elastic layer more flexible and impart cushioning property. The foaming agent is not particularly limited as long as it can impart cushioning properties to the elastic layer.

(Laminated body forming process)
This is a step of forming a first elastic body layer and / or a second elastic body layer on a support using the swellable resin composition prepared above to obtain a laminated body (FIG. 2S3). These elastic layers can be formed, for example, by applying the swellable resin composition to one side or both sides of the support and drying it. By this step, it is possible to obtain a heat radiating sheet (first heat radiating sheet) in which the elastic layer is not swelled before the swelling step.

The coating amount of the swellable resin composition can be appropriately set in consideration of the set value of the dry film thickness of the elastic body layer and the solid content of the resin composition. For example, a swellable resin composition is applied to one surface of a conductive support having a thickness of 10 μm to 50 μm so that the dry film thickness is 10 μm to 20 μm, and the temperature is 50 ° C. to 150 ° C. for 10 minutes to 90 minutes. The first elastic body layer can be formed by drying for a minute. Then, the swellable resin composition is applied to the surface opposite to the surface on which the first elastic body layer is formed so that the dry film thickness is 10 μm to 20 μm, and the temperature is 50 ° C. to 150 ° C. for 10 minutes to 90 minutes. By drying, the second elastic body layer can be formed.

(Irradiation process)
In the method for manufacturing a heat radiating sheet, the swelling step can be performed using the first heat radiating sheet, but before that, a radiation irradiation step of irradiating the first elastic body layer and / or the second elastic body layer with radiation is performed. It may be included (FIG. 2 S4). For example, in this step, the elasticity of the elastic body layer is infiltrated by infiltrating an organic solvent from the surface of the elastic body layer to the inside by reducing the average molecular weight by cutting the cross-linking of the resin component in the elastic body layer. It is possible to obtain a second heat radiating sheet having a height higher than that of the first heat radiating sheet. In the case of the second heat radiating sheet, the elastic layer after swelling can be deformed more fluidly than in the case of the first heat radiating sheet, so that the heat conductive particles contained in the elastic layer are rearranged. It is possible to follow the fine unevenness of the surface to be adhered to the adherend. As a result, it is possible to prevent air bubbles from being mixed at the adhesion interface with the adherend while containing a larger amount of thermally conductive particles, and to satisfy higher adhesion with the adherend.

The radiation used in this step is not particularly limited as long as it can cut the crosslinks of the resin component, and for example, an electron beam, a gamma ray, or an ultraviolet ray can be used.

Further, the irradiation amount of radiation can be arbitrarily set so that the cross-linking of the resin component can be cut to further increase the elasticity. For example, the absorbed dose can be 50 kGy to 500 kGy.

(Swelling process)
This is a step of swelling the first elastic body layer and / or the second elastic body layer of the first heat radiating sheet or the second heat radiating sheet with an organic solvent (FIG. 2S5). As the swelling step, for example, as shown in FIG. 3, a step of swelling by dropping an organic solvent onto the elastic layer of the first heat radiating sheet or the second heat radiating sheet (FIG. 3 (a) S5a), or an adherend. An organic solvent is dropped onto the surface to be adhered to (FIG. 3 (b) S6), and then the adherend is crimped to the first heat radiating sheet or the second heat radiating sheet (FIG. 3 (b) S7b). A step of swelling by infiltrating the surface organic solvent into the elastic layer (FIG. 3 (b) S5b) can be mentioned.

In the step of swelling the elastic layer of the first heat radiating sheet or the second heat radiating sheet by dropping the organic solvent (FIG. 3 (a) S5a), for example, the organic solvent is dropped and left for about 30 seconds to 5 minutes. Therefore, the elastic body layer can be inflated. If it is left for a short time, it may not swell sufficiently, and if it is left for a long time, the solvent may volatilize from the elastic layer and its elasticity may decrease.

<How to use the heat dissipation sheet>
The method of using the heat radiating sheet according to the embodiment of the present invention is, in order, the first elastic body layer and / or the first elastic body layer of the laminated body in which the first elastic body layer, the support layer, and the second elastic body layer are laminated. The second elastic body layer includes a swelling step of swelling with an organic solvent and a crimping step of crimping the heat radiating sheet after the swelling step to the adherend.

(Swelling process)
The first elastic body layer, the support layer, the second elastic body layer, the laminated body, the organic solvent, and the swelling step are the same as those described in the method for manufacturing the heat dissipation sheet, and the description thereof will be omitted.

(Crimping process)
Hereinafter, the crimping process will be described with reference to the flow chart shown in FIG. For example, as shown in FIG. 3A, after the step of inflating the elastic layer of the first heat dissipation sheet or the second heat dissipation sheet by dropping an organic solvent (FIG. 3A S5a), the heat dissipation sheet is used. It can be crimped to the adherend. By this step, the heat radiating sheet can be supplied between the high heat generation component and the heat radiating cooling member, and the air bubbles are mixed in the contact interface with the adherend following the unevenness of the contact surface of the adherend. Can be prevented and good adhesion to the adherend can be exhibited.

The crimping conditions are not particularly limited as long as good adhesion to the adherend can be exhibited. For example, under a temperature condition of 20 ° C to 30 ° C, after the heat radiating sheet is brought into close contact with the high heat generating component and the heat radiating cooling member, 1 kg / cm ² to 5 kg / cm ² on the contact surface for 5 to 30 seconds. It can be crimped by applying the pressure of.

Further, as shown in FIG. 3 (b), an organic solvent is dropped onto the surface to be adhered to the adherend (FIG. 3 (b) S6), and then the adherend and the first heat dissipation sheet or the second heat dissipation sheet are dropped. Can be crimped (FIG. 3 (b) S7b). The crimping conditions can be the same as described above. The crimping step of S7b can also serve as a step (FIG. 3 (b) S5b) in which the organic solvent on the surface to be adhered permeates into the elastic body layer and swells the elastic body layer.

In the method of using the heat dissipation sheet of the present invention, the elasticity of the first elastic body layer and the second elastic body layer can be adjusted by appropriately adding an organic solvent as described above. By adjusting the elasticity to a predetermined level, it follows the unevenness of the surface to be adhered to the adherend, prevents air bubbles from entering at the adhesion interface with the adherend, and exhibits good adhesion to the adherend. be able to. As a result, good thermal conductivity can be ensured between the high heat generation component and the heat dissipation cooling member. If it is adjusted to have more appropriate elasticity, it will be easier to handle when arranging the heat dissipation sheet between the high heat generation component and the heat dissipation cooling member while satisfying the good thermal conductivity shown on the left. Relocation etc. becomes easy. The elasticity is the elasticity of the elastic body layer after the first elastic body layer and / or the second elastic body layer is swollen by the organic solvent.

If the elasticity of the first elastic body layer and the second elastic body layer is insufficient, the adherence of the adherend to the unevenness of the contact target surface may be insufficient, and bubbles may be mixed. In addition, there is a risk that the adhesion to the adherend will not be satisfied. Further, if the elasticity is excessive, when crimping is performed between the high heat generating component and the heat dissipation cooling member, the elasticity may protrude from the space and adhere to a nearby circuit to short-circuit the circuit. be.

The elasticity of the first elastic body layer and the second elastic body layer can be set independently. For example, the elasticity of the first elastic body layer can be set higher or lower than the elasticity of the second elastic body layer, or can be set to the same elasticity. That is, in consideration of the mixing of air bubbles at the adhesion interface with the adherend and the adhesion with the adherend, the elasticity of each of the first elastic body layer and the second elastic body layer is set to be suitable. be able to.

When the heat-dissipating sheet is crimped between the heat-dissipating component and the heat-dissipating cooling member by the above-mentioned crimping process, the excess organic solvent that has not penetrated into the elastic layer flows, and the outer edge of the heat-generating component or the heat-dissipating cooling member flows. Is discharged from. Due to the discharge of this solvent, the ratio of the organic solvent and the resin composition in the first elastic body layer and the second elastic body layer changes, and each independently has a mass ratio of 0: 1 to 1: 1 to 0: 1 to 1. : It becomes 8. At the same time, the heat-dissipating component and the heat-dissipating cooling member are brought into close contact with the heat-dissipating sheet due to the presence of the softened elastic layer. By deforming the softened elastic body layer, it is possible to follow the fine irregularities on the surface of the adherend. Inside the softened elastic body layer, good heat transfer is possible due to the intervention of heat conductive particles, so that between the heat dissipation sheet and the adherend such as the heat-generating component and the heat-dissipating cooling member, more than before. Efficient heat exchange is possible. Due to the discharge of excess organic solvent and the maximum particle size of the heat conductive particles being 20 μm or less, which is smaller than the typical thickness of the heat dissipation sheet of 50 μm to 100 μm, the ultrathin elastic body layer is formed. The intervening form also enables efficient heat exchange between the heat dissipation sheet and the adherend.

(Example of using heat dissipation sheet)
Hereinafter, an example of using the heat radiating sheet according to the embodiment of the present invention described above will be described with reference to the schematic cross-sectional view of FIG.

In the laminate 100 shown in FIG. 4A, between a high heat generating component 50 in which a solder 30 and a power semiconductor 40 are sequentially laminated on a metal plate 20 made of copper or aluminum, and a heat sink 60 serving as a heat dissipation cooling member. The heat radiating sheet 10 is arranged on the floor. Examples of the high heat generation component 50 include a CPU (central processing unit), a transistor, a light emitting diode (LED), a power control element, and the like, and the heat generation is less remarkable than a memory element, a capacitance element (condenser), and the like. Is also a highly heat-generating component.

FIG. 4B is an enlarged cross-sectional schematic view of a portion (a portion surrounded by a dotted square in FIG. 4A) in which the metal plate 20, the heat radiating sheet 10, and the heat sink 60 of the high heat generating component 50 are laminated. .. Surface irregularities are observed on the contact target surfaces 20a and 60a of the metal plate 20 and the heat sink 60. In the heat radiating sheet of the present invention, since the first elastic body layer and the second elastic body layer have sufficient thickness and elasticity, air bubbles are mixed in the contact interface with respect to both the contact target surfaces 20a and 60a. Good adhesion can be exhibited without doing so.

The effect of the present invention is as described above, but as a further effect, even in the case of a heat dissipation sheet in which the organic solvent volatilizes after swelling and the elastic layer is once solidified, the organic solvent is supplied to the elastic layer. Viscosity and elasticity can be restored by permeating the organic solvent and softening it again.

Hereinafter, the present invention will be described in more detail with reference to examples, but the present invention is not limited to the following examples.

[Example 1]
(Preparation process of resin solution)
After putting 100 parts of ethyl acetate (mass part, the same applies hereinafter), 25 parts of ethyl cellulose, 25 parts of n-butyl acrylate, and 5.0 parts of vinyl acetate in the reaction vessel, knead at 100 ° C. for 10 minutes and vinyl acetate. Polymerized to obtain a gelled resin solution (nonvolatile content: 50% by mass).

(Preparation process of swellable resin composition)
For 100 parts of the non-volatile content of the obtained resin solution, 200 parts of spherical copper particles (maximum particle diameter: 8 μm) were used as heat conductive particles, and polymerized rosin ester was used as a tackifier [manufactured by Arakawa Chemical Industry Co., Ltd., trade name. : Pencel D-135] is mixed with a resin solution, spherical copper particles and a tackifier so that the content is 25 parts, and then ethyl acetate is added so that the content of the non-volatile content is 50% by mass. The mixture was stirred to obtain a swellable resin composition.

(Laminated body forming process)
The swellable resin composition obtained above is applied on both sides of a copper foil having a thickness of 35 μm to be a support layer, and dried in an atmosphere of 100 ° C. for 1 hour to increase the thickness after drying. A first heat dissipation sheet having a 10 μm first elastic body layer (nonvolatile content: 93% by mass) and a second elastic layer (nonvolatile content: 93% by mass) was prepared. When the inside of the first elastic body layer and the second elastic body layer after drying were observed with an SEM (scanning electron microscope), copper particles were partially bound by the remaining adhesive resin, and many pores were formed. It was confirmed that the structure had a porous structure.

(Evaluation of thermal conductivity)
As a test piece for measuring thermal conductivity, a laminate was prepared in which a copper plate (10 mm × 10 mm, thickness 500 μm), a first heat dissipation sheet (10 mm × 10 mm), and a copper plate similar to the above were laminated in order. .. Specifically, the first heat dissipation is such that the ratio of ethyl acetate contained in the first elastic body layer to the first elastic body layer (nonvolatile content: 93% by mass) is 1: 1 in mass ratio. Ethyl acetate was added dropwise to the first elastic layer of the sheet as an organic solvent, and the mixture was allowed to stand for 1 minute for swelling (swelling step). Then, while extruding the droplets of ethyl acetate, one copper plate was pressure-bonded to the first elastic body layer of the heat-dissipating sheet while avoiding the mixing of air bubbles (crimping step). The crimping conditions were 2 kg / cm ² , the crimping temperature was 25 ° C., and the crimping time was 10 seconds. Next, by performing the same swelling step and crimping step on the second elastic body layer (nonvolatile content: 93% by mass) of the first heat dissipation sheet, another copper plate is crimped to the second elastic body layer. A test piece for measuring thermal conductivity was obtained, which had a structure in which two copper plates were bonded with a first heat dissipation sheet interposed therebetween. The ratio of ethyl acetate contained in the first elastic body layer after the crimping step to the first elastic body layer (nonvolatile content: 93% by mass) was 1: 6 by mass ratio. Similarly, the ratio of ethyl acetate contained in the second elastic body layer after the crimping step to the second elastic body layer (nonvolatile content: 93% by mass) was 1: 6 by mass ratio.

The thermal conductivity of this test piece was measured using a DynaTIM tester manufactured by Mentor Graphics, and found to be 5.6 W / m · K.

[Example 2]
(Irradiation process)
The first elastic body layer and the second elastic body layer of the first heat dissipation sheet prepared in the same manner as in Example 1 were irradiated with an electron beam at an absorption dose of 500 kGy at 500 keV to cut the crosslinks of the adhesive resin composition. A second heat dissipation sheet was obtained.

(Evaluation of thermal conductivity)
Using the second heat dissipation sheet, a swelling step and a crimping step were performed in the same manner as in Example 1 to obtain a test piece for measuring thermal conductivity. The ratio of ethyl acetate contained in the first elastic body layer after the crimping step to the first elastic body layer (nonvolatile content: 93% by mass) was 1: 8 by mass ratio. Similarly, the ratio of ethyl acetate contained in the second elastic body layer after the crimping step to the second elastic body layer (nonvolatile content: 93% by mass) was 1: 8 by mass ratio. The thermal conductivity of the test piece for measuring thermal conductivity was 6.8 W / m · K.

[Example 3]
(Evaluation of thermal conductivity)
Ethyl acetate is dropped on the surface of the copper plate, and the first elastic body layer and the second elastic body layer are pressure-bonded to the copper plate using the same first heat dissipation sheet as in Example 1 to inflate each elastic body layer. (Swelling, crimping process). Other than this, a test piece for measuring thermal conductivity was obtained in the same manner as in Example 1. The ratio of ethyl acetate contained in the first elastic body layer after the crimping step to the first elastic body layer (nonvolatile content: 93% by mass) was 1: 5 by mass ratio. Similarly, the ratio of ethyl acetate contained in the second elastic body layer after the crimping step to the second elastic body layer (nonvolatile content: 93% by mass) was 1: 5 by mass ratio. The thermal conductivity of the test piece for measuring thermal conductivity was 5.6 W / m · K.

[Example 4]
Other than using 25 parts of n-butyl acrylate instead of 25 parts of ethyl acrylate, the resin solution preparation step, the swellable resin composition preparation step, the laminate forming step, and the thermal conductivity are the same as in Example 1. Evaluation was performed. The ratio of ethyl acetate contained in the first elastic body layer after the crimping step to the first elastic body layer (nonvolatile content: 96% by mass) was 1: 6 by mass ratio. Similarly, the ratio of ethyl acetate contained in the second elastic body layer after the crimping step to the second elastic body layer (nonvolatile content: 96% by mass) was 1: 6 by mass ratio. The thermal conductivity of the test piece for measuring thermal conductivity was 5.7 W / m · K.

[Example 5]
As in Example 1, the procedure for preparing the resin solution and the swelling resin composition were the same as in Example 1, except that 100 parts of amorphous zinc oxide particles (maximum particle diameter: 10 μm) were used instead of 200 parts of spherical copper particles as the heat conductive particles. The preparation process, the laminate formation process, and the thermal conductivity were evaluated. The ratio of ethyl acetate contained in the first elastic body layer after the crimping step to the first elastic body layer (nonvolatile content: 93% by mass) was 1: 6 by mass ratio. Similarly, the ratio of ethyl acetate contained in the second elastic body layer after the crimping step to the second elastic body layer (nonvolatile content: 93% by mass) was 1: 6 by mass ratio. The thermal conductivity of the test piece for measuring thermal conductivity was 3.1 W / m · K.

[Example 6]
The first elastic body layer and the second elastic body layer of the first heat dissipation sheet prepared in the same manner as in Example 1 were irradiated with gamma rays at an absorbed dose of 500 kGy using Co60 as a radiation source to cut the crosslinks of the adhesive resin composition. Then, a second heat dissipation sheet was obtained. The evaluation of thermal conductivity was performed under the same conditions as in Example 2. The ratio of ethyl acetate contained in the first elastic body layer after the crimping step to the first elastic body layer (nonvolatile content: 96% by mass) was 1: 8 by mass ratio. Similarly, the ratio of ethyl acetate contained in the second elastic body layer after the crimping step to the second elastic body layer (nonvolatile content: 96% by mass) was 1: 8 by mass ratio. The thermal conductivity of the test piece for measuring thermal conductivity was 6.6 W / m · K.

[Comparative Example 1]
Similar to Example 1, the resin solution preparation step, the swellable resin composition preparation step, the laminate forming step, and the evaluation of thermal conductivity were carried out, except that the swelling step was not carried out because ethyl acetate was not used. Was done. The thermal conductivity of the test piece for measuring thermal conductivity was 4.8 W / m · K.

[summary]
The thermal conductivity of the heat dissipation sheets of Examples 1 to 6 was higher than that of Comparative Example 1. In Examples 1 to 6, the first elastic layer and the second elastic layer were swollen by the use of an organic solvent, and the elasticity was improved by appropriately cutting the crosslinks of the adhesive resin composition. It is considered that the efficiency of heat conduction is improved by preventing the mixing of air bubbles with the elastic layer and by sufficiently following the unevenness of the copper plate surface with the elastic layer.

On the other hand, in Comparative Example 1, by not using the organic solvent, the first elastic layer and the second elastic layer did not swell, and as a result, the effect of preventing air bubbles from being mixed between the copper plate and the elastic layer and the surface of the copper plate. It is probable that the thermal conductivity was inferior to that of Examples 1 to 6 because the effect of the elastic layer following the unevenness of the above was sufficient.

From the above, according to the present invention, it is possible to provide a heat radiating sheet capable of ensuring good thermal conductivity between a high heat generating component and a heat radiating cooling member, a method for manufacturing the heat radiating sheet, and a method for using the heat radiating sheet. It's clear.

Although the preferred embodiments of the present invention have been described in detail above, the present invention is not limited to such examples. It is clear that a person having ordinary knowledge in the field of technology to which the present invention belongs can come up with various modifications or modifications within the scope of the technical ideas described in the claims. , These are also naturally understood to belong to the technical scope of the present invention.

1 1st elastic body layer 2 Support layer 3 2nd elastic body layer 4 Laminated body 10 Heat dissipation sheet 20 Metal plate 20a Adhesion target surface 30 Solder 40 Power semiconductor 50 High heat generation parts 60 Heat sink 60a Adhesion target surface 100 Laminated body

Claims (6)

In order,
A first elastic layer containing thermally conductive particles, containing a resin composition that swells with an organic solvent, and having adhesiveness,
A support layer with thermal conductivity and
A second elastic layer containing thermally conductive particles, containing a resin composition that swells with an organic solvent, and having adhesiveness,
Equipped with a laminated body in which
The organic solvent is contained in at least one of the first elastic body layer and the second elastic body layer.
The ratio of the organic solvent to the resin composition in the first elastic body layer and the second elastic body layer is 0: 1 to 1: 8 in terms of mass ratio, respectively.
The first elastic body layer and / or the second elastic body layer is an elastic body layer irradiated with radiation.
Heat dissipation sheet. The heat dissipation sheet according to claim 1, wherein the thickness of the first elastic body layer and the thickness of the second elastic body layer are independently 10 μm to 20 μm, respectively. In order,
A first elastic layer containing thermally conductive particles, containing a resin composition that swells with an organic solvent, and having adhesiveness, and
A support layer with thermal conductivity and
A second elastic layer containing thermally conductive particles, containing a resin composition that swells with an organic solvent, and having adhesiveness, and
Including a swelling step of swelling the first elastic body layer and / or the second elastic body layer of the laminated body to be laminated with the organic solvent.
In the swelling step, the ratio of the organic solvent to the resin composition of the first elastic body layer and the ratio of the organic solvent to the resin composition of the second elastic body layer are independently measured by mass ratio. It is 0: 1 to 1: 1 and
The swelling step comprises an irradiation step of irradiating the first elastic body layer and / or the second elastic body layer with radiation.
The method for manufacturing a heat dissipation sheet according to claim 1 or 2. The method for manufacturing a heat dissipation sheet according to claim 3, wherein the radiation is an electron beam or a gamma ray. In order,
A first elastic layer containing thermally conductive particles, containing a resin composition that swells with an organic solvent, and having adhesiveness,
A support layer with thermal conductivity and
A second elastic layer containing thermally conductive particles, containing a resin composition that swells with an organic solvent, and having adhesiveness,
A swelling step of swelling the first elastic body layer and / or the second elastic body layer with the organic solvent of the heat radiating sheet provided with the laminated body to be laminated.
Including a crimping step of crimping the heat radiating sheet to the adherend after the swelling step.
In the swelling step, the ratio of the organic solvent to the resin composition of the first elastic body layer and the ratio of the organic solvent to the resin composition of the second elastic body layer are independently measured by mass ratio. It is 0: 1 to 1: 1 and
Prior to the swelling step, the irradiation step of irradiating the first elastic body layer and / or the second elastic body layer with radiation is included.
How to use the heat dissipation sheet. The method of using the heat dissipation sheet according to claim 5, wherein the radiation is an electron beam or a gamma ray.

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