JP6862601B1 - Thermal conductive sheet and its manufacturing method, mounting method of thermal conductive sheet - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat conductive sheet having excellent adhesion to electronic components, handleability and reworkability, a method for manufacturing the same, and a method for mounting the heat conductive sheet. SOLUTION: The sheet body 2 is formed by curing a binder resin containing at least a polymer matrix component and a heat conductive filler, and the volume ratio of the heat conductive filler to the polymer matrix component is 1.00. ~ 1.70, the thermally conductive filler contains the fibrous thermally conductive filler 10, and the fibrous thermally conductive filler 10 protrudes from the surface of the sheet body 2. [Selection diagram] Fig. 1

Description

The present technology relates to a heat conductive sheet that is attached to an electronic component or the like to improve its heat dissipation.

Conventionally, in semiconductor elements mounted on various electric devices such as personal computers and other devices, heat is generated by driving, and when the generated heat is accumulated, the driving of semiconductor elements and peripheral devices are adversely affected. Therefore, various cooling means are used. Examples of cooling methods for electronic components such as semiconductor elements include a method of attaching a fan to the device to cool the air inside the device housing, and a method of attaching a heat sink such as a heat radiating fin or a heat sink to the semiconductor element to be cooled. Are known.

When a heat sink is attached to a semiconductor element for cooling, a heat conductive sheet is provided between the semiconductor element and the heat sink in order to efficiently release the heat of the semiconductor element. As the heat conductive sheet, a sheet in which a heat conductive filler such as carbon fiber is dispersed and contained in a silicone resin is widely used (see Patent Document 1). The fibrous heat conductive filler has anisotropy of heat conduction. For example, when carbon fiber is used as the fibrous heat conductive filler, about 600 W / m · K ~ in the fiber direction. It has a thermal conductivity of 1200 W / m · K, and when boron nitride is used, it has a thermal conductivity of about 110 W / m · K in the plane direction and about 2 W / m · K in the direction perpendicular to the plane direction. It is known to have and have anisotropy.

Japanese Unexamined Patent Publication No. 2012-0233335 Japanese Unexamined Patent Publication No. 2015-029076 Japanese Unexamined Patent Publication No. 2015-029075

Here, the amount of heat radiation of electronic components such as CPUs of personal computers tends to increase year by year as the speed and performance of electronic components increase. However, on the contrary, the chip size of the processor and the like has become the same size as or smaller than the conventional size due to the progress of the fine silicon circuit technology, and the heat flow velocity per unit area has become high. Therefore, in order to avoid problems due to the temperature rise, it is required to dissipate heat and cool electronic components such as a CPU more efficiently.

In order to improve the heat dissipation characteristics of the heat conductive sheet, it is required to reduce the thermal resistance, which is an index indicating the difficulty of heat transfer. In order to reduce the thermal resistance, it is effective to improve the adhesion to electronic parts that are heating elements and heat-dissipating parts such as heat sinks, and to reduce the thermal resistance by thinning the heat conductive sheet.

When the heat conductive molded body is sliced thinly to form a heat conductive sheet, the surface of the sliced sheet is uneven and the adhesion to electronic parts is poor. If the adhesion is poor, problems such as dropping from the component due to non-adhesion to the component occur in the mounting process, and air is contained due to poor adhesion to the heat radiator such as an electronic component or a heat sink. Therefore, there is a problem that the thermal resistance cannot be sufficiently lowered.

To solve this problem, the surface of the heat conductive sheet made by slicing the heat conductive molded product is pressed or left to stand for a long time to exude the uncured component of the binder resin to the surface. The adhesion between the heat conductive sheet and the electronic component is improved (see Patent Documents 2 and 3). Further, in such a technique, as in the heat conductive sheet 100 shown in FIG. 5, the protrusion of the fibrous heat conductive filler 110 from the sheet surface 200a of the sheet body 200 is reduced, and the sheet surface 200a is not yet formed. It has tackiness by increasing the amount of curing component.

On the other hand, if the uncured component of the binder resin exudes onto the surface of the sheet, adhesiveness is imparted, which causes a problem of poor handleability. Therefore, a thermally conductive sheet having tack property (adhesiveness) at the time of mounting the electronic component but having reduced tack property before mounting is preferable.

In addition, the heat conductive sheet is required to have reworkability such as correcting the positional deviation when assembling the electronic component and the heat radiating member, or disassembling the heat conductive sheet for some reason and then reassembling it. .. That is, the heat conductive sheet exhibits tackiness as before the load is applied even after the load is applied by being sandwiched between the electronic component and the heat radiating member and the load is removed. It is preferable that the product can be mounted on an electronic component and has the same handleability and adhesion as before the load is applied.

Therefore, an object of the present technology is to provide a heat conductive sheet having excellent adhesion to electronic components, handleability, and reworkability, a method for manufacturing the same, and a method for mounting the heat conductive sheet.

In order to solve the above-mentioned problems, the heat conductive sheet according to the present technology has a sheet body obtained by curing a heat conductive resin composition containing at least a polymer matrix component and a heat conductive filler. The volume ratio of the heat conductive filler to the polymer matrix component is 1.00 to 1.70, the heat conductive filler contains the fibrous heat conductive filler, and the fibrous heat conductive. The sex filler protrudes from the surface of the sheet body.

Further, in the method for producing a heat conductive sheet according to the present technology, a heat conductive resin composition containing a fibrous heat conductive filler in a polymer matrix component is molded into a predetermined shape, cured, and heated. It has a step of forming a conductive molded body and a step of slicing the heat conductive molded body into a sheet to form a heat conductive sheet, and the volume of the heat conductive filler with respect to the polymer matrix component. The ratio is 1.00 to 1.70, the heat conductive filler contains a fibrous heat conductive filler, and the fibrous heat conductive filler protrudes from the surface of the sheet body. It is a thing.

Further, the method for mounting the heat conductive sheet according to the present technology is the method for mounting the heat conductive sheet which is placed on the electronic component and sandwiched between the heat conductive member and the heat conductive member. By applying a load to the heat conductive sheet, tackiness is exhibited and attached to the electronic component, and when the heat conductive sheet is reattached, the load is released, the electronic component is peeled off, and the above again. The heat conductive sheet has a step of sticking on electronic parts, and the above heat conductive sheet has a sheet body obtained by curing a heat conductive resin composition containing at least a polymer matrix component and a fibrous heat conductive filler. The volume ratio of the heat conductive filler to the polymer matrix component is 1.00 to 1.70, and the heat conductive filler contains a fibrous heat conductive filler and is fibrous. The heat conductive filler is one that protrudes from the surface of the sheet body.

In order to solve the above-mentioned problems, the heat conductive sheet according to the present technology has a sheet body obtained by curing a heat conductive resin composition containing at least a polymer matrix component and a heat conductive filler. The content of the heat conductive filler is 50 to 63% by volume, the heat conductive filler contains the fibrous heat conductive filler, and the fibrous heat conductivity in the heat conductive filler. The volume ratio of the filler is 0.20 to 0.42, and the fibrous thermally conductive filler protrudes from the surface of the sheet body.

Further, in the method for producing a heat conductive sheet according to the present technology, a heat conductive resin composition containing a fibrous heat conductive filler in a polymer matrix component is molded into a predetermined shape, cured, and heated. It has a step of forming a conductive molded body and a step of slicing the heat conductive molded body into a sheet to form a heat conductive sheet, and the content of the heat conductive filler is 50 to 63. By volume%, the heat conductive filler contains a fibrous heat conductive filler, and the volume ratio of the fibrous heat conductive filler in the heat conductive filler is 0.20 to 0.42. The fibrous thermally conductive filler protrudes from the surface of the sheet body.

Further, the method for mounting the heat conductive sheet according to the present technology is the method for mounting the heat conductive sheet which is placed on the electronic component and sandwiched between the heat conductive member and the heat conductive member. By applying a load to the heat conductive sheet, tackiness is exhibited and attached to the electronic component, and when the heat conductive sheet is reattached, the load is released, the electronic component is peeled off, and the above again. The heat conductive sheet has a step of sticking on electronic parts, and the above heat conductive sheet has a sheet body obtained by curing a heat conductive resin composition containing at least a polymer matrix component and a fibrous heat conductive filler. The content of the heat conductive filler is 50 to 63% by volume, the heat conductive filler contains the fibrous heat conductive filler, and the fibrous heat in the heat conductive filler. The volume ratio of the conductive filler is 0.20 to 0.42, and the fibrous thermally conductive filler protrudes from the surface of the sheet body.

According to the present technology, the tackiness is reduced or eliminated by projecting the fibrous heat conductive filler on the surface of the sheet. Further, in actual use, when a load is applied to the seat body, tackiness is exhibited. Therefore, the heat conductive sheet has good handleability and workability because the tackiness is reduced or eliminated before mounting, and the tackiness is exhibited at the time of mounting, so that the sheet surface has irregularities. In addition, the adhesion to electronic parts and heat radiating members is improved, and the thermal resistance is reduced.

Further, in the heat conductive sheet according to the present technology, when the applied load is released, the sheet body is restored to a thickness of 90% or more. At this time, the tackiness is reduced or eliminated. Therefore, even when the heat conductive sheet is subjected to remounting, the handleability and adhesion are the same as those at the beginning, and the reworkability is excellent.

FIG. 1 is a cross-sectional view showing a heat conductive sheet to which the present technology is applied. FIG. 2 is a perspective view showing an example of a step of slicing a thermally conductive molded product. FIG. 3 is a cross-sectional view showing a process of pressing a heat conductive sheet to which a release film is attached. FIG. 4 is a cross-sectional view showing an example of a semiconductor device. FIG. 5 is a cross-sectional view showing a conventional heat conductive sheet.

Hereinafter, the heat conductive sheet to which the present technology is applied, its manufacturing method, and the mounting method of the heat conductive sheet will be described in detail with reference to the drawings. It should be noted that the present technology is not limited to the following embodiments, and it goes without saying that various changes can be made without departing from the gist of the present technology. In addition, the drawings are schematic, and the ratio of each dimension may differ from the actual one. Specific dimensions, etc. should be determined in consideration of the following explanation. In addition, it goes without saying that the drawings include parts having different dimensional relationships and ratios from each other.

The thermally conductive sheet to which the present technology is applied has a sheet body obtained by curing a thermally conductive resin composition containing at least a polymer matrix component (binder resin) and a fibrous thermally conductive filler. Further, in the heat conductive sheet, the volume ratio of the heat conductive filler to the polymer matrix component is 1.00 to 1.70, and the heat conductive filler contains a fibrous heat conductive filler. Further, the fibrous thermally conductive filler protrudes from the surface of the sheet body and is coated with an uncured component of the binder resin.

In such a heat conductive sheet, the tack property is reduced or eliminated by projecting the fibrous heat conductive filler on the sheet surface. Further, in actual use, when a load is applied to the sheet body by pressing in advance or by being sandwiched between an electronic component and a heat radiating member, the fibrous heat conduction protruding on the sheet surface. The sex filler is buried in the sheet body, and the uncured component of the binder resin supported in the sheet body exudes, whereby tackiness is exhibited. Therefore, the heat conductive sheet has good handleability and workability because the tackiness is reduced or eliminated before mounting, and the tackiness is exhibited at the time of mounting, so that the sheet surface has irregularities. In addition, the adhesion to electronic parts and heat radiating members is improved, and the thermal resistance is reduced.

Further, in the heat conductive sheet, the volume ratio of the heat conductive filler to the polymer matrix component is set to 1.00 to 1.70, so that the load is applied at the time of mounting on an electronic component or the like, and then Even when the load is released due to factors such as correcting the misalignment, the seat body is restored to a thickness of 90% or more. At this time, the fibrous heat conductive filler buried in the sheet body also protrudes onto the sheet surface again, and the tackiness is reduced or disappears. Therefore, even when the heat conductive sheet is subjected to remounting, the handleability and adhesion are the same as those at the beginning, and the reworkability is excellent.

When the volume ratio of the heat conductive filler to the polymer matrix component is more than 1.70, the recovery rate of the sheet thickness is less than 90%, and the protruding length of the carbon fiber from the sheet surface is shortened. Tack remains and it is inferior in reworkability. Further, if the volume ratio of the heat conductive filler to the polymer matrix component is less than 1.00, the thermal resistance may increase.

Further, the heat conductive sheet to which the present technology is applied has a sheet body obtained by curing a heat conductive resin composition containing at least a polymer matrix component and a heat conductive filler. Further, the heat conductive sheet has a heat conductive filler content of 50 to 63% by volume, the heat conductive filler contains a fibrous heat conductive filler, and the fibrous heat in the heat conductive filler. The volume ratio of the conductive filler is 0.22 to 0.42. Further, the fibrous thermally conductive filler protrudes from the surface of the sheet body and is coated with the uncured component of the binder resin.

Even with such a heat conductive sheet, the tackiness is reduced or eliminated by projecting the fibrous heat conductive filler on the sheet surface. Further, in actual use, when a load is applied to the sheet body by pressing in advance or by being sandwiched between an electronic component and a heat radiating member, the fibrous heat conduction protruding on the sheet surface. The sex filler is buried in the sheet body, and the uncured component of the binder resin supported in the sheet body exudes, whereby tackiness is exhibited. Therefore, the heat conductive sheet has good handleability and workability because the tackiness is reduced or eliminated before mounting, and the tackiness is exhibited at the time of mounting, so that the sheet surface has irregularities. In addition, the adhesion to electronic parts and heat radiating members is improved, and the thermal resistance is reduced.

Further, the heat conductive sheet has a content of the heat conductive filler of 50 to 63% by volume and a volume ratio of the fibrous heat conductive filler in the heat conductive filler of 0.22 to 0.42. By doing so, the seat body recovers to a thickness of 90% or more even when the load is released due to factors such as correcting the positional deviation after the load is applied at the time of mounting on electronic parts, etc. Will be done. At this time, the fibrous heat conductive filler buried in the sheet body also protrudes onto the sheet surface again, and the tackiness is reduced or disappears. Therefore, even when the heat conductive sheet is subjected to remounting, the handleability and adhesion are the same as those at the beginning, and the reworkability is excellent.

When the content of the heat conductive filler is more than 63% by volume, the recovery rate of the sheet thickness is less than 90%, the protrusion length of the carbon fiber from the sheet surface is shortened, and therefore the tack remains. , Inferior in reworkability. Further, if the volume ratio of the fibrous heat conductive filler in the heat conductive filler is less than 0.22, tack remains, the reworkability is inferior, and the thermal resistance may increase.

[Thermal conductive sheet]
FIG. 1 shows a heat conductive sheet 1 to which the present technology is applied. The heat conductive sheet 1 has a sheet body 2 obtained by curing a heat conductive resin composition containing at least a polymer matrix component (binder resin) and a fibrous heat conductive filler.

A fibrous heat conductive filler 10 described later is projected on the surface 2a of the sheet body 2. As a result, the tack property of the heat conductive sheet 1 is reduced or eliminated. Here, the reduction or disappearance of tackiness means that the tackiness is reduced to the extent that a person does not feel stickiness when touched, whereby the heat conductive sheet 1 can be handled and worked. The sex is improved. The heat conductive sheet 1 is covered with the heat conductive filler 10 in which a small amount of the uncured component 11 of the binder resin exudes from the sheet body 2 and protrudes to the surface. The tackiness is reduced or eliminated by projecting the thermally conductive filler 10 from the sheet surface to a predetermined length or longer.

(Polymer matrix component)
The polymer matrix component constituting the sheet body 2 is a polymer component that serves as a base material for the heat conductive sheet 1. The type is not particularly limited, and a known polymer matrix component can be appropriately selected. For example, one of the polymer matrix components is a thermosetting polymer.

Examples of the thermosetting polymer include crosslinked rubber, epoxy resin, polyimide resin, bismaleimide resin, benzocyclobutene resin, phenol resin, unsaturated polyester, diallyl phthalate resin, silicone resin, polyurethane, polyimide silicone, and thermosetting type. Examples thereof include polyimideene ether and thermosetting modified polyphenylene ether. These may be used alone or in combination of two or more.

Examples of the crosslinked rubber include natural rubber, butadiene rubber, isoprene rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene propylene rubber, chlorinated polyethylene, chlorosulfonated polyethylene, butyl rubber, halogenated butyl rubber, and fluorine. Examples thereof include rubber, urethane rubber, acrylic rubber, polyisobutylene rubber, and silicone rubber. These may be used alone or in combination of two or more.

Further, among these thermosetting polymers, it is preferable to use a silicone resin from the viewpoints of excellent molding processability and weather resistance, as well as adhesion and followability to electronic components. The silicone resin is not particularly limited, and the type of silicone resin can be appropriately selected depending on the intended purpose.

From the viewpoint of obtaining the above-mentioned molding processability, weather resistance, adhesion and the like, the silicone resin is preferably a silicone resin composed of a main agent of a liquid silicone gel and a curing agent. Examples of such a silicone resin include an addition reaction type liquid silicone resin, a hot vulcanization type mirable type silicone resin using a peroxide for vulcanization, and the like. Among these, the addition reaction type liquid silicone resin is particularly preferable as the heat radiating member of the electronic device because the adhesion between the heat generating surface and the heat sink surface of the electronic component is required.

As the addition reaction type liquid silicone resin, it is preferable to use a two-component addition reaction type silicone resin or the like using a polyorganosiloxane having a vinyl group as a main agent and a polyorganosiloxane having a Si—H group as a curing agent. ..

Here, the liquid silicone component has a silicone A liquid component as a main agent and a silicone B liquid component containing a curing agent, and the blending ratio of the silicone A liquid component and the silicone B liquid component is the amount of the silicone A liquid component. Is preferably contained in an amount equal to or greater than the amount of the silicone B liquid component. As a result, the thermally conductive sheet 1 imparts flexibility to the sheet body 2, and also exudes the uncured component of the polymer matrix component in the binder resin onto the surfaces 2a and 2b of the sheet body 2 by the pressing process to tack. Sex can be expressed.

Further, in the heat conductive sheet of the present invention, the volume ratio of the heat conductive filler to the polymer matrix component is 1.00 to 1.70, or the content of the heat conductive filler is 50 to 63. By setting the volume%, the recovery rate after removing the applied load can be set to 90% or more, and reworkability can be provided.

[Fibrous thermally conductive filler]
The fibrous heat conductive filler contained in the heat conductive sheet 1 is a component for improving the heat conductivity of the sheet. The type of the heat conductive filler is not particularly limited as long as it is a fibrous material having high heat conductivity, but it is preferable to use carbon fiber from the viewpoint of obtaining higher heat conductivity.

The heat conductive filler may be used alone or in combination of two or more. When two or more kinds of thermally conductive fillers are used, all of them may be fibrous thermally conductive fillers, or have a different shape from the fibrous thermally conductive fillers. It may be used in combination with a filler.

The type of the carbon fiber is not particularly limited and may be appropriately selected depending on the intended purpose. For example, pitch type, PAN type, graphitized PBO fiber, arc discharge method, laser evaporation method, CVD method (chemical vapor deposition method), CCVD method (catalytic chemical vapor deposition method), etc. Can be used. Among these, carbon fibers obtained by graphitizing PBO fibers and pitch-based carbon fibers are more preferable from the viewpoint of obtaining high thermal conductivity.

Further, the carbon fiber can be used by surface-treating a part or all of the carbon fiber, if necessary. The surface treatment includes, for example, oxidation treatment, nitriding treatment, nitration, sulfonate treatment, or attachment of a metal, a metal compound, an organic compound, or the like to the surface of a functional group or carbon fiber introduced into the surface by these treatments. Examples include the process of combining. Examples of the functional group include a hydroxyl group, a carboxyl group, a carbonyl group, a nitro group, an amino group and the like.

Further, the average fiber length (average major axis length) of the carbon fibers is not particularly limited and can be appropriately selected, but it should be in the range of 50 μm to 300 μm from the viewpoint of surely obtaining high thermal conductivity. , More preferably in the range of 75 μm to 275 μm, and particularly preferably in the range of 90 μm to 250 μm.

Furthermore, the average fiber diameter (average minor axis length) of the carbon fibers is not particularly limited and can be appropriately selected, but is in the range of 4 μm to 20 μm from the viewpoint of surely obtaining high thermal conductivity. It is preferably in the range of 5 μm to 14 μm, and more preferably in the range of 5 μm to 14 μm.

The aspect ratio (average major axis length / average minor axis length) of the carbon fibers is preferably 8 or more, and more preferably 9 to 30 from the viewpoint of surely obtaining high thermal conductivity. .. If the aspect ratio is less than 8, the fiber length (major axis length) of the carbon fibers is short, so that the thermal conductivity may decrease. On the other hand, if it exceeds 30, in the thermally conductive sheet. There is a risk that sufficient thermal conductivity cannot be obtained because the dispersibility of the material is reduced.

Here, the average major axis length and the average minor axis length of the carbon fibers can be measured by, for example, a microscope, a scanning electron microscope (SEM), or the like, and the average can be calculated from a plurality of samples.

The content of the fibrous heat conductive filler in the heat conductive sheet 1 is not particularly limited as long as the volume ratio to the polymer matrix component is 1.00 to 1.70, depending on the purpose. However, it is preferably 4% by volume to 40% by volume, more preferably 5% by volume to 35% by volume. If the content is less than 4% by volume, it may be difficult to obtain a sufficiently low thermal resistance, and if it exceeds 40% by volume, the moldability of the heat conductive sheet 1 and the fibrous heat It may affect the orientation of the conductive filler. Further, the content of the heat conductive filler containing the fibrous heat conductive filler in the heat conductive sheet 1 is preferably 15% by volume to 75% by volume, and particularly the content of the heat conductive filler. It is preferable that the volume ratio is 50 to 63% by volume and the volume ratio of the fibrous thermally conductive filler in the thermally conductive filler is 0.22 to 0.42.

[Sheet surface protrusion / silicone coating]
The fibrous thermally conductive filler protrudes from the surface of the sheet body 2 and is coated with an uncured component of the binder resin. The protruding length of the fibrous thermally conductive filler from the surface of the sheet body 2 is preferably longer than 50 μm. As a result, before mounting the heat conductive sheet 1, the tackiness is reduced or eliminated, and workability and handleability can be improved.

Since the fibrous heat conductive filler is coated with the uncured component in the heat conductive sheet 1, the contact thermal resistance can be reduced when it is mounted on an electronic component or the like. Further, in the heat conductive sheet 1, the uncured component of the binder resin is present on the surface 2a of the sheet body 2, but the fibrous heat conductive filler protrudes, so that it is tacky with the feeling of a finger during work. However, when it is mounted on an electronic component or the like, it adheres to it and enables work such as alignment.

The length of the fibrous heat conductive filler protruding from the surface of the sheet body 2 refers to the length from the base to the tip of the fibrous heat conductive filler protruding from the surface of the sheet body 2. Further, in the heat conductive sheet 1, the tackiness can be reduced or eliminated by projecting the fibrous heat conductive filler from the surface of the sheet body 2 for more than 50 μm, but the fibers protruding from the surface 2a of the sheet body 2. The length may be appropriately adjusted by the step of slicing into a sheet, which will be described later, according to the amount of the heat conductive filler. The protruding length of the carbon fibers from the surface of the sheet body 2 can be measured using a high-magnification actual state microscope.

[Inorganic filler]
The heat conductive sheet 1 may further contain an inorganic filler as a heat conductive filler. By containing the inorganic filler, the thermal conductivity of the thermally conductive sheet 1 can be further enhanced, and the strength of the sheet can be improved. The shape, material, average particle size, and the like of the inorganic filler are not particularly limited and may be appropriately selected depending on the intended purpose. Examples of the shape include a spherical shape, an elliptical spherical shape, a lump shape, a granular shape, a flat shape, a needle shape, and the like. Among these, a spherical shape and an elliptical shape are preferable from the viewpoint of filling property, and a spherical shape is particularly preferable.

Examples of the material of the inorganic filler include aluminum nitride (aluminum nitride: AlN), silica, alumina (aluminum oxide), boron nitride, titania, glass, zinc oxide, silicon carbide, silicon (silicon), silicon oxide, and metal particles. And so on. These may be used alone or in combination of two or more. Among these, alumina, boron nitride, aluminum nitride, zinc oxide, and silica are preferable, and alumina and aluminum nitride are particularly preferable from the viewpoint of thermal conductivity.

Further, as the inorganic filler, a surface-treated one can be used. When the inorganic filler is treated with a coupling agent as the surface treatment, the dispersibility of the inorganic filler is improved and the flexibility of the heat conductive sheet is improved.

The average particle size of the inorganic filler can be appropriately selected depending on the type of the inorganic substance and the like. When the inorganic filler is alumina, the average particle size thereof is preferably 1 μm to 10 μm, more preferably 1 μm to 5 μm, and particularly preferably 4 μm to 5 μm. If the average particle size is less than 1 μm, the viscosity may increase and it may be difficult to mix. On the other hand, if the average particle size exceeds 10 μm, the thermal resistance of the heat conductive sheet 1 may increase.

Further, when the inorganic filler is aluminum nitride, the average particle size thereof is preferably 0.3 μm to 6.0 μm, more preferably 0.3 μm to 2.0 μm, and 0.5 μm to 1. It is particularly preferably 5 μm. If the average particle size is less than 0.3 μm, the viscosity may increase and it may be difficult to mix, and if it exceeds 6.0 μm, the thermal resistance of the heat conductive sheet 1 may increase.

The average particle size of the inorganic filler can be measured by, for example, a particle size distribution meter or a scanning electron microscope (SEM).

[Other ingredients]
The thermally conductive sheet 1 may appropriately contain other components depending on the purpose, in addition to the above-mentioned polymer matrix component, fibrous thermally conductive filler, and appropriately contained inorganic filler. Examples of other components include magnetic metal powders, thixotropy-imparting agents, dispersants, curing accelerators, retarders, slight tackifiers, plasticizers, flame retardants, antioxidants, stabilizers, colorants and the like. Be done. Further, the electromagnetic wave absorption performance may be imparted to the heat conductive sheet 1 by adjusting the content of the magnetic metal powder.

[Manufacturing method of thermally conductive sheet]
Next, the manufacturing process of the heat conductive sheet 1 will be described. In the manufacturing process of the heat conductive sheet 1 to which this technique is applied, a heat conductive resin composition containing a fibrous heat conductive filler and other heat conductive fillers in a binder resin is molded into a predetermined shape. And harden to form a heat conductive molded body (step A), and a step of slicing the heat conductive molded body into a sheet to form a heat conductive sheet (step B), if necessary. The present invention includes a step (step C) of exuding the uncured component of the binder resin by pressing the heat conductive sheet.

[Step A]
In this step A, the above-mentioned polymer matrix component (binder resin), fibrous heat conductive filler, appropriately contained inorganic filler, and other components are blended to prepare a heat conductive resin composition. As described above, in the method for producing a heat conductive sheet to which this technique is applied, the volume ratio of the heat conductive filler to the polymer matrix component is adjusted to be 1.00 to 1.70. Alternatively, the content of the heat conductive filler is adjusted to 50 to 63% by volume, and the volume ratio of the fibrous heat conductive filler in the heat conductive filler is adjusted to 0.22 to 0.42. The procedure for blending and preparing each component is not particularly limited. For example, a fibrous thermally conductive filler, an inorganic filler, a magnetic metal powder, and other components are added to the polymer matrix component and mixed. By doing so, the heat conductive resin composition is prepared.

Next, a fibrous heat conductive filler such as carbon fiber is oriented in one direction. The method of aligning the filler is not particularly limited as long as it can be oriented in one direction. For example, by extruding or press-fitting the thermally conductive resin composition into a hollow mold under a high shearing force, the fibrous thermally conductive filler can be oriented in one direction relatively easily. , The orientation of the fibrous thermally conductive filler is the same (within ± 10 °).

Specific examples of the above-mentioned method of extruding or press-fitting the thermally conductive resin composition into the hollow mold under a high shearing force include an extrusion molding method and a mold molding method. In the extrusion molding method, when the heat conductive resin composition is extruded from a die, or in the mold molding method, when the heat conductive resin composition is press-fitted into a mold, the heat conductive resin composition is formed. It flows and the fibrous thermally conductive filler is oriented along the flow direction. At this time, if a slit is attached to the tip of the die, the fibrous thermally conductive filler can be more easily oriented.

The heat conductive resin composition extruded or press-fitted into a hollow mold was molded into a block shape according to the shape and size of the mold, and maintained the orientation state of the fibrous heat conductive filler. By curing the polymer matrix component as it is, a thermally conductive molded product is formed. The heat conductive molded body refers to a base material (molded body) for cutting out a sheet that is the source of the heat conductive sheet 1 obtained by cutting into a predetermined size.

The size and shape of the hollow mold and the heat conductive molded body can be determined according to the required size and shape of the heat conductive sheet 1. For example, the vertical size of the cross section is 0.5 cm or more. A rectangular parallelepiped having a width of 15 cm and a lateral size of 0.5 cm to 15 cm can be mentioned. The length of the rectangular parallelepiped may be determined as needed.

The method and conditions for curing the polymer matrix component can be changed according to the type of the polymer matrix component. For example, when the polymer matrix component is a thermosetting resin, the curing temperature in the thermosetting can be adjusted. Further, when the thermosetting resin contains a main agent of a liquid silicone gel and a curing agent, it is preferable to perform curing at a curing temperature of 80 ° C. to 120 ° C. The curing time in heat curing is not particularly limited, but may be 1 hour to 10 hours.

Here, in step A, not all of the polymer matrix components are cured, but uncured components are supported. This uncured component exudes to the sheet surface by pressing the heat conductive sheet, and can impart tackiness to the sheet surface.

[Step B]
As shown in FIG. 2, in step B in which the heat conductive molded body 6 is sliced into a sheet to form the heat conductive sheet 1, the oriented fibrous heat conductive filler is subjected to the longitudinal direction. The heat conductive molded body 6 is cut into a sheet so as to have an angle of 0 ° to 90 °. As a result, the thermally conductive filler 10 is oriented in the thickness direction of the sheet body.

Further, the heat conductive molded body 6 is cut by using a slicing device. The slicing device is not particularly limited as long as it is a means capable of cutting the thermally conductive molded body 6, and a known slicing device can be appropriately used. For example, an ultrasonic cutter, a plane (plane), or the like can be used.

The slice thickness of the heat conductive molded body 6 is the thickness of the sheet body 2 of the heat conductive sheet 1, and can be appropriately set according to the use of the heat conductive sheet 1, for example, 0.5 to 3.0 mm. is there.

In step B, the heat conductive sheet 1 cut out from the heat conductive molded body 6 may be cut into small pieces into a plurality of heat conductive sheets 1.

In the heat conductive sheet 1 manufactured through the above steps, the fibrous heat conductive filler is projected on the surface of the sheet body 2 which is the slice surface, and the tackiness is reduced or eliminated. As a result, the heat conductive sheet 1 is improved in handleability and workability.

[Step C]
In the manufacturing process of the heat conductive sheet 1, if necessary, there may be a step C in which the uncured component of the binder resin is exuded by pressing the heat conductive sheet 1. As a result, the heat conductive sheet 1 can be coated on both sides with the uncured component of the binder resin exuded from the sheet body 2 to exhibit tackiness.

The press can be performed using, for example, a pair of press devices including a flat plate and a press head having a flat surface. Alternatively, a pinch roll may be used for pressing.

The pressure at the time of pressing is not particularly limited and can be appropriately selected depending on the purpose. However, if it is too low, the thermal resistance tends to be the same as that without pressing, and if it is too high, the sheet stretches. Since there is a tendency, the pressure range is preferably 0.1 MPa to 100 MPa, and more preferably 0.5 MPa to 95 MPa.

Here, as described above, in the heat conductive molded product, the entire amount of the polymer matrix component is not cured, and in the molded product sheet, the uncured component of the binder resin (polymer matrix component) is formed on the sheet body. Is supported, and a part of the uncured component is efficiently exuded to the sheet surface by the pressing process. As a result, the heat conductive sheet 1 has a tack property on the sheet surface.

In addition, by undergoing the pressing process, the uncured component of the binder resin is supported on the surface 2a of the heat conductive sheet 1, which also increases the adhesion of the heat conductive sheet 1 and makes interfacial contact under a light load. Resistance can be reduced.

As described above, according to the present technology, the uncured component can be exuded and covered over the entire surface of the sheet even from the sheet body which is thinly cut and does not contain a large amount of the uncured component of the binder resin. Further, while the binder resin is cured and is relatively hard and has excellent shape retention, the uncured component is exuded and covered over the entire surface of the sheet even from the sheet body which does not contain a large amount of the uncured component of the binder resin. Can be done.

Therefore, according to the heat conductive sheet manufactured by the present technology, the adhesion to the electronic component and the heat radiating member can be improved and the thermal resistance can be reduced regardless of the unevenness of the sheet surface. Further, according to the heat conductive sheet manufactured by the present technology, it is not necessary to apply an adhesive for adhering to the electronic parts and the heat radiating member on the sheet surface, and the thermal resistance of the sheet does not increase. Furthermore, the heat conductive sheet containing the heat conductive filler in the binder resin not only can reduce the thermal resistance from the low load region, but also has excellent tacking force (adhesive force), and has excellent mountability and thermal characteristics. Can be improved.

[Release film]
In the above-mentioned step C, as shown in FIG. 3, it is preferable to press the heat conductive sheet 1 with the plastic film 11 attached to at least one surface, preferably both sides. As the plastic film, for example, a PET film is used. Further, the plastic film may be peeled off from the surface to be attached to the surface of the molded product sheet.

By attaching the plastic film 11 to the surface of the sheet body 2 of the heat conductive sheet 1, the uncured components exuded on the sheet surface in the pressing process are held on the sheet surface by the tension acting with the plastic film 11. It is possible to form a resin coating layer that covers the entire surface of the sheet.

When the plastic film of the heat conductive sheet 1 is peeled off during actual use, the surface of the sheet having adhesiveness is exposed, and the heat conductive sheet 1 is used for mounting on electronic parts or the like.

[Example of usage pattern]
In actual use, the heat conductive sheet 1 is appropriately peeled off from the plastic film 11 and mounted inside, for example, an electronic component such as a semiconductor device or various electronic devices. At this time, the heat conductive sheet 1 has reduced or disappeared tackiness on the surface of the sheet body 2, or has a plastic film 11 attached to it, so that it is excellent in handleability and is pressed against an electronic component or the like to carry a load. When is applied, tack develops and workability is excellent.

As shown in FIG. 4, for example, the heat conductive sheet 1 is mounted on a semiconductor device 50 built in various electronic devices and sandwiched between a heat source and a heat radiating member. The semiconductor device 50 shown in FIG. 4 has at least an electronic component 51, a heat spreader 52, and a heat conductive sheet 1, and the heat conductive sheet 1 is sandwiched between the heat spreader 52 and the electronic component 51. By using the thermally conductive sheet 1, the semiconductor device 50 has high heat dissipation and is also excellent in the electromagnetic wave suppression effect depending on the content of the magnetic metal powder in the binder resin.

The electronic component 51 is not particularly limited and may be appropriately selected depending on the intended purpose. Examples thereof include various semiconductor elements such as a CPU, MPU, graphic calculation element, and image sensor, an antenna element, and a battery. The heat spreader 52 is not particularly limited as long as it is a member that dissipates heat generated by the electronic component 51, and can be appropriately selected depending on the intended purpose. The heat conductive sheet 1 is sandwiched between the heat spreader 52 and the electronic component 51. Further, the heat conductive sheet 1 is sandwiched between the heat spreader 52 and the heat sink 53 to form a heat radiating member that dissipates heat of the electronic component 51 together with the heat spreader 52.

Of course, the mounting location of the heat conductive sheet 1 is not limited to between the heat spreader 52 and the electronic component 51 or between the heat spreader 52 and the heat sink 53, and can be appropriately selected according to the configuration of the electronic device or semiconductor device. is there. In addition to the heat spreader 52 and the heat sink 53, the heat radiating member may be any one that conducts heat generated from the heat source and dissipates it to the outside. For example, a radiator, a cooler, a die pad, a printed circuit board, and a cooling fan. , Peltier element, heat pipe, metal cover, housing and the like.

[Workability, reworkability]
In addition, the heat conductive sheet 1 is reworked by correcting the misalignment, disassembling it for some reason after assembling it once, peeling it off from the electronic parts, etc., and reattaching it again due to factors such as reassembling. be able to. At this time, the heat conductive sheet 1 is attached to the electronic component by exhibiting tackiness by applying a load when it is placed on the electronic component or the like, and then when the heat conductive sheet is reattached. Releases the load, is peeled off from the electronic component, etc., and is reattached to the electronic component, etc.

Here, as described above, in the heat conductive sheet 1 to which the present technology is applied, the volume ratio of the heat conductive filler to the polymer matrix component (binder resin) is 1.00 to 1.70. .. Alternatively, the heat conductive sheet 1 to which the present technology is applied has a heat conductive filler content of 50 to 63% by volume, and the volume ratio of the fibrous heat conductive filler in the heat conductive filler is 0. It is said to be .22 to 0.42. Further, the fibrous thermally conductive filler protrudes from the surface of the sheet body 2 and is coated with an uncured component of the binder resin.

In such a heat conductive sheet 1, the sheet body 2 is restored to a thickness of 90% or more even when the load is released after the load is applied at the time of mounting on an electronic component or the like.

Further, the heat conductive sheet 1 in which the volume ratio of the heat conductive filler to the polymer matrix component (binder resin) is 1.00 to 1.70 has appropriate flexibility and is a heat conductive molded body. The surface roughness on the sliced surface is low when sliced into a sheet, for example, the maximum Rz value also contains a fibrous heat conductive filler as a heat conductive filler, and the volume ratio is larger than 1.70. Lower than the sex sheet. Further, the Rz value further decreases after the load is applied, but the difference in the Rz value before and after the load is applied includes the fibrous heat conductive filler as the heat conductive filler and the volume ratio is 0.6. Smaller than a larger thermal conductive sheet.

Further, the heat conductive sheet has a content of the heat conductive filler of 50 to 63% by volume and a volume ratio of the fibrous heat conductive filler in the heat conductive filler of 0.22 to 0.42. No. 1 has appropriate flexibility and has a low surface roughness on the sliced surface when the heat conductive molded body is sliced into a sheet. For example, the maximum Rz value is also fibrous heat conductive filling as a heat conductive filler. The content of the heat conductive filler containing the agent is lower than that of the heat conductive sheet having a content of more than 63% by volume. Further, the Rz value further decreases after the load is applied, but the difference in the Rz value before and after the load is applied includes the fibrous thermally conductive filler as the thermally conductive filler and contains the thermally conductive filler. The amount is smaller than the thermally conductive sheet, which is larger than 63% by volume.

The thermally conductive sheet 1 having such a low Rz value after the release of the applied load and a recovery rate of 90% or more in thickness after the release of the applied load described above is fibrous heat after the release of the applied load. The protrusion length of the conductive filler from the sheet surface is the same as the initial length.

That is, the heat conductive sheet 1 is once peeled off from the electronic component or the like, and the fibrous heat conductive filler protrudes again on the sheet surface, so that the tack property is reduced or eliminated. Then, when a load is applied to the sheet body 2 by pressing in advance or being sandwiched between the electronic component and the heat radiating member at the time of reattachment, the fibrous heat protruding on the sheet surface is generated. The conductive filler is buried in the sheet body 2, and the uncured component of the binder resin supported in the sheet body 2 exudes, whereby tackiness is exhibited again.

Therefore, the heat conductive sheet has good handleability and workability by reducing or eliminating the tackiness before mounting even during the rework work, and the tackiness is exhibited at the time of mounting, so that the sheet is exhibited. Even when the surface has irregularities, the adhesion to the electronic parts and the heat radiating member is improved, and the thermal resistance can be reduced.

It should be noted that such a heat conductive sheet 1 has the same effect and has good workability not only during the rework work but also when the press step is provided in advance before the first mounting work.

Next, examples of the present technology will be described. In this embodiment, a silicone composition (thermally conductive resin composition) containing carbon fibers as a fibrous thermally conductive filler and alumina is prepared to form a cured silicone product (thermally conductive molded body). , A heat conductive sheet was obtained by slicing into a sheet. The obtained heat conductive sheet is pressed, and the sheet thickness before and after the press, ^{the thermal resistance of the sample before and after the press applied with a load of 0.8 kgf / cm 2} by a method conforming to ASTM-D5470, and the durometer hardness standard before and after the press. The type OO hardness in ASTM-D2240, the distance of carbon fibers from the surface of the heat conductive sheet before and after pressing, and the surface roughness (Rz value) of the heat conductive sheet before and after pressing were evaluated.

[Example 1]
In Example 1, as shown in Table 1, 46.2% by volume of mixed alumina particles having an average particle size of 1 μm and 5 μm obtained by coupling a two-component addition reaction type liquid silicone with a silane coupling agent, an average fiber. A silicone composition was prepared by mixing 14% by volume of pitch-based carbon fibers having a length of 200 μm. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 53:47. The total amount of the binder resin in Example 1 is 39.8% by volume, the blending amount of the carbon fibers is 14% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.35. The content of the heat conductive filler is 60.2% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.51, and the volume ratio of carbon fibers in the heat conductive filler is 0. It is .23.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 1.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Example 2]
In Example 2, the cured silicone product prepared in Example 1 was cut with a slicer so as to have a thickness of 2.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes. The total amount of the binder resin in Example 2 is 39.8% by volume, the blending amount of the carbon fibers is 14% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.35. The content of the heat conductive filler is 60.2% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.51, and the volume ratio of carbon fibers in the heat conductive filler is 0. It is .23.

[Example 3]
In Example 3, the cured silicone product prepared in Example 1 was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes. The total amount of the binder resin in Example 3 is 39.8% by volume, the blending amount of the carbon fibers is 14% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.35. The content of the heat conductive filler is 60.2% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.51, and the volume ratio of carbon fibers in the heat conductive filler is 0. It is .23.

[Example 4]
In Example 4, as shown in Table 1, 46.2% by volume of mixed alumina particles having an average particle size of 1 μm and 5 μm obtained by coupling a two-component addition reaction type liquid silicone with a silane coupling agent, an average fiber. A silicone composition was prepared by mixing 14% by volume of pitch-based carbon fibers having a length of 200 μm. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 58:42. The total amount of the binder resin in Example 4 is 39.8% by volume, the blending amount of the carbon fibers is 14% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.35. The content of the heat conductive filler is 60.2% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.51, and the volume ratio of carbon fibers in the heat conductive filler is 0. It is .23.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Example 5]
In Example 5, as shown in Table 1, 46.2% by volume of mixed alumina particles having an average particle size of 1 μm and 5 μm and an average fiber obtained by coupling a two-component addition reaction type liquid silicone with a silane coupling agent. A silicone composition was prepared by mixing 14% by volume of pitch-based carbon fibers having a length of 200 μm. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 50:50. The total amount of the binder resin in Example 5 is 39.8% by volume, the blending amount of the carbon fibers is 14% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.35. The content of the heat conductive filler is 60.2% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.51, and the volume ratio of carbon fibers in the heat conductive filler is 0. It is .23.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Example 6]
In Example 6, as shown in Table 1, 36% by volume of mixed alumina particles having an average particle size of 1 μm and 5 μm and an average fiber length of 200 μm obtained by coupling a two-component addition reaction type liquid silicone with a silane coupling agent. 14% by volume of pitch-based carbon fibers were mixed to prepare a silicone composition. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 53:47. The total amount of the binder resin in Example 6 is 50% by volume, the blending amount of the carbon fibers is 14% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.28. The content of the heat conductive filler is 50% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.00, and the volume ratio of carbon fibers in the heat conductive filler is 0.28. Is.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Example 7]
In Example 7, as shown in Table 1, 49% by volume of mixed alumina particles having an average particle size of 1 μm and 5 μm and an average fiber length of 200 μm obtained by coupling a two-component addition reaction type liquid silicone with a silane coupling agent. 14% by volume of pitch-based carbon fibers were mixed to prepare a silicone composition. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 53:47. The total amount of the binder resin in Example 7 is 37% by volume, the blending amount of the carbon fibers is 14% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.38. The content of the heat conductive filler is 63% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.70, and the volume ratio of carbon fibers in the heat conductive filler is 0.22. Is.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Example 8]
In Example 8, as shown in Table 1, 35.2% by volume of mixed alumina particles having an average particle size of 1 μm and 5 μm and an average fiber obtained by coupling a two-component addition reaction type liquid silicone with a silane coupling agent. A silicone composition was prepared by mixing 25% by volume of pitch-based carbon fibers having a length of 200 μm. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 53:47. The total amount of the binder resin in Example 8 is 39.8% by volume, the blending amount of the carbon fibers is 25% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.63. The content of the heat conductive filler is 60.2% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.51, and the volume ratio of carbon fibers in the heat conductive filler is 0. It is .42.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Example 9]
In Example 9, as shown in Table 1, 48.2% by volume of mixed alumina particles having an average particle size of 1 μm and 5 μm obtained by coupling a two-component addition reaction type liquid silicone with a silane coupling agent, an average fiber. A silicone composition was prepared by mixing 12% by volume of pitch-based carbon fibers having a length of 200 μm. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 53:47. The total amount of the binder resin in Example 9 is 39.8% by volume, the blending amount of the carbon fibers is 12% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.30. The content of the heat conductive filler is 60.2% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.51, and the volume ratio of carbon fibers in the heat conductive filler is 0. .20.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Example 10]
In Example 10, as shown in Table 1, a pitch of 45% by volume of mixed alumina particles having an average particle size of 4 μm and an average fiber length of 150 μm obtained by coupling a two-component addition reaction type liquid silicone with a silane coupling agent. 14% by volume of the based carbon fiber was mixed to prepare a silicone composition. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 47:53. The total amount of the binder resin in Example 10 is 39.8% by volume, the blending amount of the carbon fibers is 14% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.35. The content of the heat conductive filler is 59% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.48, and the volume ratio of carbon fibers in the heat conductive filler is 0.24. Is.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Comparative Example 1]
In Comparative Example 1, as shown in Table 2, 42.5% by volume of mixed alumina particles having an average particle size of 4 μm and an average fiber length of 150 μm obtained by coupling a two-component addition reaction type liquid silicone with a silane coupling agent. 23% by volume of pitch-based carbon fibers were mixed to prepare a silicone composition. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 58:42. The total amount of the binder resin in Comparative Example 1 is 34.1% by volume, the blending amount of the carbon fibers is 23% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.67. The content of the heat conductive filler is 65.5% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.92, and the volume ratio of carbon fibers in the heat conductive filler is 0. It is .35.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 1.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Comparative Example 2]
In Comparative Example 2, the cured silicone product prepared in Comparative Example 1 was cut with a slicer so as to have a thickness of 2.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes. The total amount of the binder resin in Comparative Example 2 is 34.1% by volume, the blending amount of the carbon fibers is 23% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.67. The content of the heat conductive filler is 65.5% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.92, and the volume ratio of carbon fibers in the heat conductive filler is 0. It is .35.

[Comparative Example 3]
In Comparative Example 3, the cured silicone product prepared in Comparative Example 1 was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes. The total amount of the binder resin in Comparative Example 3 is 34.1% by volume, the blending amount of the carbon fibers is 23% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.67. The content of the heat conductive filler is 65.5% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.92, and the volume ratio of carbon fibers in the heat conductive filler is 0. It is .35.

[Comparative Example 4]
In Comparative Example 4, as shown in Table 2, 51% by volume of aluminum hydroxide particles having an average particle size of 5 μm and 12% by volume of pitch-based carbon fibers having an average fiber length of 150 μm were mixed with a two-component addition reaction type liquid silicone. Then, a silicone composition was prepared. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 50:50. The total amount of the binder resin in Comparative Example 4 is 36.4% by volume, the blending amount of the carbon fibers is 12% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.33. The content of the heat conductive filler is 63% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.73, and the volume ratio of carbon fibers in the heat conductive filler is 0.19. Is.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Comparative Example 5]
In Comparative Example 5, as shown in Table 2, 51% by volume of aluminum hydroxide particles having an average particle size of 5 μm and 12% by volume of pitch-based carbon fibers having an average fiber length of 150 μm were mixed with a two-component addition reaction type liquid silicone. Then, a silicone composition was prepared. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 58:42. The total amount of the binder resin in Comparative Example 5 is 36.4% by volume, the blending amount of the carbon fibers is 12% by volume, and the volume ratio of the carbon fibers to the binder resin is 0.33. The content of the heat conductive filler is 63% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 1.73, and the volume ratio of carbon fibers in the heat conductive filler is 0.19. Is.

The obtained silicone composition was extruded into a hollow square columnar mold (50 mm × 50 mm) to mold a 50 mm □ silicone molded product. The silicone molded product was heated in an oven at 100 ° C. for 6 hours to obtain a cured silicone product. The cured silicone product was cut with a slicer so as to have a thickness of 3.0 mm to obtain a heat conductive sheet. Next, the heat conductive sheet was sandwiched between the peeled PET films, and the heat conductive sheet was pressed under the conditions of 87 ° C., 0.5 MPa, and 3 minutes.

[Comparative Example 6]
In Comparative Example 6, as shown in Table 2, 70.6% by volume of aluminum hydroxide particles having an average particle size of 1 μm and an average particle size of 5 μm obtained by coupling a two-component addition reaction type liquid silicone with a silane coupling agent. A silicone composition was prepared by mixing 5.2% by volume of aluminum hydroxide particles and 3.3% by volume of alumina particles having an average particle size of 4 μm. The two-component addition reaction type liquid silicone resin used was mainly composed of organopolysiloxane, and was blended so that the blending ratio of the silicone A agent and the B agent was 58:42. The total amount of the binder resin in Comparative Example 6 is 18.8% by volume, the blending amount of the carbon fibers is 0% by volume, and the volume ratio of the carbon fibers to the binder resin is 0. The content of the heat conductive filler is 79.1% by volume, the volume ratio of the heat conductive filler to the total amount of binder resin is 4.21, and the volume ratio of carbon fibers in the heat conductive filler is 0. Is.

The obtained silicone composition was sandwiched between stripped PET and coated with a bar coater so as to have a thickness of 1 mm, and heated at 100 ° C. for 6 hours in an open state to obtain a heat conductive sheet.

[Comparative Example 7]
In Comparative Example 7, as shown in Table 2, the conditions were the same as those in Comparative Example 6 except that the obtained silicone composition was sandwiched between stripped PET and coated with a bar coater so as to have a thickness of 2 mm.

[Comparative Example 8]
In Comparative Example 8, as shown in Table 2, the conditions were the same as those in Comparative Example 6 except that the obtained silicone composition was sandwiched between stripped PET and coated with a bar coater so as to have a thickness of 3 mm.

As shown in Table 1, the heat conductive sheet according to Example 1-10 has a volume ratio of the heat conductive filler to the polymer matrix component (binder resin) of 1.00 to 1.70, or Since the content of the heat conductive filler is 50 to 63% by volume and the volume ratio of the fibrous heat conductive filler in the heat conductive filler is 0.22 to 0.42, the durometer hardness standard ASTM- The value of type OO in D2240 is 15 to 40, which is lower than that of Comparative Example 1-5. In addition, the Rz value was improved after pressing, and the recovery rate of the sheet thickness was 90% or more. Therefore, in the heat conductive sheet according to Example 1-10, the protrusion length of the carbon fibers from the sheet surface before and after pressing was 60 μm, which was almost the same before and after pressing and was 50 μm or more. In each of the heat conductive sheets according to Examples 1-10, the thermal resistance when a load of ^{0.3 kgf / cm 2 was applied before and after pressing was 1.9 ° C. cm 2} / W or less. there were.

The heat conductive sheet itself according to Examples 1-10 has no tack property and can be freely moved on the glass plate, but when pressed against the glass plate with a finger, tack develops and adheres to the glass. I was able to confirm that. Therefore, according to Example 1-10, the tackiness of the sheet surface is reduced or eliminated before mounting, the handleability and workability are excellent, the tackiness is exhibited by pressing, and the adhesion to electronic parts and the like is exhibited. It was found that a thermally conductive sheet capable of excellent reworkability as well as excellent thermal resistance can be obtained.

On the other hand, in the heat conductive sheet according to Comparative Example 1-5, the volume ratio of the heat conductive filler to the polymer matrix component (binder resin) is larger than 1.70, or the content of the heat conductive filler is large. Since the volume ratio of the fibrous thermally conductive filler is more than 63% by volume or less than 0.22 in the thermally conductive filler, the value of type OO in the durometer hardness standard ASTM-D2240 is also as high as 55 or more. Further, although the Rz value was relatively improved after pressing, the recovery rate of the sheet thickness was less than 90%, and the protruding length of the carbon fiber from the sheet surface was as short as 10 μm. Therefore, the heat conductive sheet cannot be freely moved on the glass plate, and it is difficult to align the heat conductive sheet. In addition, the heat conductive sheet after peeling had a residual tack and was inferior in reworkability. The heat conductive sheet according to Comparative Example 6-8 does not contain a fibrous heat conductive filler and has a tack property on the sheet surface. Therefore, as in Comparative Example 1-5, the handleability and rework are similar to those of Comparative Example 1-5. It was inferior in sex.

1 Thermally conductive sheet, 2 Sheet body, 10 Fibrous thermally conductive filler

Claims (12)

It has a sheet body obtained by curing a heat conductive resin composition containing at least a polymer matrix component and a heat conductive filler.
The volume ratio of the heat conductive filler to the polymer matrix component is 1.00 to 1.70.
The heat conductive filler contains a fibrous heat conductive filler, and the heat conductive filler contains a fibrous heat conductive filler.
A heat conductive sheet in which the fibrous heat conductive filler protrudes from the surface of the sheet body. The heat conductive sheet according to claim 1, wherein the heat conductive filler has a protruding length from the surface of the sheet body of more than 50 μm. The heat conductive sheet according to claim 1, wherein the heat conductive filler is oriented in the thickness direction of the sheet body. The heat conductive sheet according to any one of claims 1 to 3, wherein the value of type OO in the durometer hardness standard ASTM-D2240 is 15 to 40. The invention according to any one of claims 1 to 3, wherein the sheet body is compressed with a load of 0.8 kgf / cm ² and the thickness of the sheet body is restored to 90% or more of that before compression after the load is released. Thermal conductivity sheet. According to any one of claims 1 to 4, the difference in surface roughness Rz before and after the application of the load of the sheet body is 8 or less after the load is applied to the sheet body to compress and the load is released. The heat conductive sheet described. The heat conductive sheet according to any one of claims 1 to 5, wherein the thermal resistance when a load of 0.3 kgf / cm ² is applied is 1.9 ° C. cm ^{2 / W or less.} A step of molding a thermally conductive resin composition containing a fibrous thermally conductive filler in a polymer matrix component into a predetermined shape and curing the composition to form a thermally conductive molded body.
It has a step of slicing the heat conductive molded product into a sheet to form a heat conductive sheet.
The volume ratio of the heat conductive filler to the polymer matrix component is 1.00 to 1.70.
The heat conductive filler contains a fibrous heat conductive filler.
The fibrous heat conductive filler is a method for producing a heat conductive sheet that protrudes from the surface of the sheet body. It has a sheet body obtained by curing a heat conductive resin composition containing at least a polymer matrix component and a heat conductive filler.
The content of the heat conductive filler is 50 to 63% by volume.
The heat conductive filler contains a fibrous heat conductive filler.
The volume ratio of the fibrous heat conductive filler in the heat conductive filler is 0.20 to 0.42.
A heat conductive sheet in which the fibrous heat conductive filler protrudes from the surface of the sheet body. A step of molding a thermally conductive resin composition containing a fibrous thermally conductive filler in a polymer matrix component into a predetermined shape and curing the composition to form a thermally conductive molded body.
It has a step of slicing the heat conductive molded product into a sheet to form a heat conductive sheet.
The content of the heat conductive filler is 50 to 63% by volume.
The heat conductive filler contains a fibrous heat conductive filler, and the heat conductive filler contains a fibrous heat conductive filler.
The volume ratio of the fibrous heat conductive filler in the heat conductive filler is 0.20 to 0.42.
The fibrous heat conductive filler is a method for producing a heat conductive sheet that protrudes from the surface of the sheet body. In the method of mounting a heat conductive sheet that is placed on an electronic component and sandwiched between it and a heat radiating member,
When it is placed on the electronic component, a load is applied to the heat conductive sheet to develop tackiness and attach it to the electronic component.
When the heat conductive sheet is reattached, it has a step of releasing the load, peeling from the electronic component, and reattaching the heat conductive sheet on the electronic component.
The heat conductive sheet is
It has a sheet body obtained by curing a heat conductive resin composition containing at least a polymer matrix component and a fibrous heat conductive filler.
The volume ratio of the heat conductive filler to the polymer matrix component is 1.00 to 1.70.
The heat conductive filler contains a fibrous heat conductive filler, and the heat conductive filler contains a fibrous heat conductive filler.
The fibrous heat conductive filler is a method for mounting a heat conductive sheet protruding from the surface of the sheet body. In the method of mounting a heat conductive sheet that is placed on an electronic component and sandwiched between it and a heat radiating member,
When it is placed on the electronic component, a load is applied to the heat conductive sheet to develop tackiness and attach it to the electronic component.
When the heat conductive sheet is reattached, it has a step of releasing the load, peeling from the electronic component, and reattaching the heat conductive sheet on the electronic component.
The heat conductive sheet is
It has a sheet body obtained by curing a heat conductive resin composition containing at least a polymer matrix component and a fibrous heat conductive filler.
The content of the heat conductive filler is 50 to 63% by volume.
The heat conductive filler contains a fibrous heat conductive filler, and the heat conductive filler contains a fibrous heat conductive filler.
The volume ratio of the fibrous heat conductive filler in the heat conductive filler is 0.20 to 0.42.
The fibrous heat conductive filler is a method for mounting a heat conductive sheet protruding from the surface of the sheet body.

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