阅读说明：本技术 导热性片的制造方法 (Method for manufacturing thermally conductive sheet ) 是由 荒卷庆辅 户端真理奈 于 2019-07-11 设计创作，主要内容包括：本申请涉及导热性片的制造方法。本发明的课题是提供使粘合剂树脂的未固化成分高效地渗出至成型体片的表面,提高了密合性的导热性片的制造方法。作为解决本发明课题的方法,提供一种导热性片的制造方法,其包括下述工序：使在粘合剂树脂中含有导热性填料的导热性树脂组合物成型成预定的形状并固化,形成导热性成型体的工序,将上述导热性成型体切削成片状,形成成型体片的工序,以及在减压环境下将上述成型体片进行压制,从而利用从上述成型体片的片主体渗出的上述粘合剂树脂的未固化成分来被覆上述成型体片的表面的工序。(The present invention relates to a method for manufacturing a thermally conductive sheet, wherein uncured components of a binder resin are efficiently diffused to the surface of a molded body sheet to improve adhesion, and a method for manufacturing thermally conductive sheets is provided as a method for solving the problems of the present invention, the method comprising a step of forming a thermally conductive molded body by molding a thermally conductive resin composition containing a thermally conductive filler in a binder resin into a predetermined shape and curing the composition, a step of forming a molded body sheet by cutting the thermally conductive molded body into a sheet shape, and a step of covering the surface of the molded body sheet with the uncured components of the binder resin diffused from the sheet main body of the molded body sheet by pressing the molded body sheet in a reduced pressure environment.)

1, A method for producing a thermally conductive sheet, comprising the steps of:

a step of forming a thermally conductive resin composition containing a thermally conductive filler in a binder resin into a predetermined shape and curing the composition to form a thermally conductive formed body,

a step of cutting the thermally conductive molded body into a sheet shape to form a molded body sheet, and

and a step of pressing the molded body sheet in a reduced pressure environment to coat the surface of the molded body sheet with uncured components of the binder resin that have oozed out of the sheet main body of the molded body sheet.

2. The method for producing a thermally conductive sheet according to claim 1, wherein a vacuum pressure x in a reduced-pressure environment is in a range of-5.0 kPa. ltoreq.x.ltoreq.0.1 kPa when the atmospheric pressure is zero.

3. The method for producing a thermally conductive sheet according to claim 1 or 2, wherein the pressing is performed in a state in which a release film is attached to at least surfaces of the molded body sheet.

4. The method for producing the thermally conductive sheet according to any of claims 1 to 3, wherein the molded body sheet has a thickness of 0.2mm to 1.0 mm.

5. The method for producing a thermally conductive sheet according to any of claims 1 to 4, wherein the binder resin is a liquid silicone component, and the thermally conductive filler is carbon fiber.

6. The method for producing a thermally conductive sheet according to claim 5, wherein the liquid silicone component comprises a silicone liquid A component as a main component and a silicone liquid B component containing a curing agent, and the amount of the silicone liquid A component contained is equal to or greater than the amount of the silicone liquid B component.

Technical Field

The present invention relates to a method for manufacturing a heat conductive sheet that is attached to an electronic component or the like and improves heat dissipation properties thereof.

Background

Conventionally, various cooling methods have been used for semiconductor devices mounted in various electrical devices such as personal computers and other devices, because heat is generated by operation and if the generated heat is accumulated, the operation of the semiconductor devices and peripheral devices are adversely affected. As a method for cooling an electronic component such as a semiconductor element, there are known: a method of installing a fan in the equipment to cool air in the equipment case; and a method of mounting a heat sink such as a heat sink or a heat radiation plate on the semiconductor element to be cooled.

A thermal conductive sheet comprising a silicone resin and a filler such as a thermal conductive filler such as carbon fiber dispersed therein is widely used as the thermal conductive sheet (see patent document 1). these thermal conductive fillers have thermal conductivity anisotropy, and it is known that, for example, carbon fiber has thermal conductivity of about 600W/m.k to 1200W/m.k in the fiber direction when carbon fiber is used as the thermal conductive filler, about 110W/m.k in the plane direction when boron nitride is used, about 2W/m.k in the direction perpendicular to the plane direction, and anisotropy.

Disclosure of Invention

Problems to be solved by the invention

Here, as electronic components such as CPUs of personal computers are increased in speed and performance, heat dissipation tends to increase year by year. On the contrary, the chip size of a processor or the like is equivalent to or smaller than the conventional size due to the progress of the fine silicon circuit technology, and the heat flow rate per unit area is increased. Therefore, in order to avoid a trouble due to the temperature rise, it is required to efficiently dissipate and cool the heat of the electronic components such as the CPU.

In order to improve the heat dissipation characteristics of the heat conductive sheet, it is required to reduce the thermal impedance, which is an index indicating the difficulty of heat conduction. In order to reduce the thermal impedance, it is effective to improve the adhesion to a heat sink such as an electronic component or a heat sink which is a heat generating element, and to reduce the thermal impedance by thinning the heat conductive sheet.

When the thermally conductive molded body is cut into a sheet to form a thermally conductive sheet, the cut sheet surface has irregularities and lacks adhesiveness. If the adhesion is poor, the adhesion with the part is not good and the trouble such as dropping off the part occurs in the mounting process, and the adhesion with the electronic part as a heating element and a heat sink or other heat radiator is poor, and air is included, and the thermal resistance cannot be sufficiently reduced.

In order to solve such a problem, there has been proposed a technique of improving adhesion between a heat conductive sheet and an electronic component by pressing the surface of the heat conductive sheet produced by cutting a heat conductive molded body or leaving the heat conductive sheet for a long time to allow uncured components of a binder resin to bleed out to the surface (see patent documents 2 and 3).

However, a thin heat conductive sheet has a problem that the uncured component of the binder resin is less in comparison with a thick heat conductive sheet, and the binder does not sufficiently ooze out to the sheet surface even when pressed, and the binder does not uniformly ooze out to the sheet surface, and variation in adhesion occurs depending on the position of the surface of the heat conductive sheet, and thermal resistance increases.

Further, if the heat conductive sheet cut into a sheet is a soft sheet containing a large amount of uncured components, there is a problem that the shape cannot be maintained due to elongation when pressure is applied between the electronic component and the heat dissipating member for a long time, and is another aspect that if the heat conductive sheet is a hard heat conductive sheet, the uncured components of the binder resin are small, and the adhesive does not easily bleed out even when pressed, and the surface of the cover sheet is not reached, and the adhesion is improved.

Accordingly, an object of the present invention is to provide a method for producing a thermally conductive sheet, in which uncured components of a binder resin are efficiently bled out to the surface of a molded sheet, and adhesion is improved.

Means for solving the problems

In order to solve the above problems, a method for manufacturing a thermally conductive sheet according to the present invention includes the steps of: the method for manufacturing the molded article includes a step of molding a thermally conductive resin composition containing a thermally conductive filler in a binder resin into a predetermined shape and curing the molded article to form a thermally conductive molded body, a step of cutting the thermally conductive molded body into a sheet shape to form a molded article sheet, and a step of pressing the molded article sheet in a reduced pressure environment to coat the surface of the molded article sheet with uncured components of the binder resin that have oozed out of the sheet main body of the molded article sheet.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, the heat conductive sheet can efficiently bleed out uncured components of the binder resin carried by the sheet main body and coat the sheet surface by pressing the molded body sheet in a reduced pressure environment.

Drawings

Fig. 1 is a sectional view showing a thermal conductive sheet to which the present invention is applied.

Fig. 2 is a perspective view of an example showing a step of cutting the thermally conductive molded body.

Fig. 3 is a sectional view showing a step of pressing the molded body sheet to which the release film is attached in a reduced pressure atmosphere.

Fig. 4 is a cross-sectional view of examples showing a semiconductor device.

Description of the symbols

1 heat conductive sheet 1, 2 sheet main bodies, 3 release film, 5 resin coating layer, 6 heat conductive molded body, 7 molded body sheet.

Detailed Description

Hereinafter, a method for manufacturing a thermal conductive sheet to which the present invention is applied will be described in detail with reference to the drawings. The present invention is not limited to the following embodiments, and various modifications can be made without departing from the scope of the present invention. The drawings are schematic, and the ratio of the dimensions and the like may be different from the actual ratio. Specific dimensions and the like should be judged with reference to the following description. It is to be noted that the drawings naturally include portions having different dimensional relationships and ratios from each other.

The method for manufacturing a thermally conductive sheet to which the present invention is applied includes the steps of: the method for manufacturing the molded article includes a step (step A) of molding a thermally conductive resin composition containing a thermally conductive filler in a binder resin into a predetermined shape and curing the molded article to form a thermally conductive molded body, a step (step B) of cutting the thermally conductive molded body into a sheet shape to form a molded article sheet, and a step (step C) of pressing the molded article sheet in a reduced pressure environment to coat the surface of the molded article sheet with uncured components of the binder resin that have oozed out from the sheet main body of the molded article sheet.

The thermally conductive sheet produced through the above steps can carry uncured components of the binder resin that do not contribute to the reaction in the sheet main body of the molded sheet, and by pressing the molded sheet in a reduced pressure environment, the uncured components of the binder resin carried by the sheet main body can be efficiently exuded to coat the sheet surface.

Thus, according to the present invention, even from a sheet main body which is cut thinly and does not contain a large amount of uncured component containing a binder resin, the uncured component can be oozed out over the entire surface of the sheet surface to be coated. Further, even from the sheet main body which is hard and excellent in shape retention property by being cured with the binder resin and does not contain a large amount of uncured components containing the binder resin, the uncured components can be exuded over the entire surface of the sheet surface to be coated.

Therefore, the thermally conductive sheet produced by the present invention can improve the adhesion to electronic components and heat dissipating members and reduce the thermal resistance regardless of the irregularities on the sheet surface, and the thermally conductive sheet produced by the present invention does not require an adhesive agent for adhering the thermally conductive sheet to electronic components and heat dissipating members to be applied to the sheet surface, and the thermal resistance of the sheet does not increase, and is a step of improving the mountability and thermal characteristics while reducing the thermal resistance from a low load region and having excellent adhesive force (adhesive force) for a thermally conductive sheet containing a thermally conductive filler in a binder resin.

[ constitution of thermally conductive sheet ]

Fig. 1 shows a thermal conductive sheet 1 to which the present invention is applied. The thermally conductive sheet 1 has a sheet main body 2, and the sheet main body 2 is formed by curing a binder resin containing at least a polymer matrix component and a thermally conductive filler. Both surfaces of the sheet main body 2 are coated with uncured components of the binder resin oozing from the sheet main body 2, thereby forming a resin coating layer 5. The heat conductive sheet 1 has release films 3 adhered to both surfaces of the sheet main body 2, and uncured components of the binder resin constituting the resin coating layer 5 are held between the release films 3 and the sheet main body 2.

The both surfaces of the sheet main body 2 of the thermal conductive sheet 1 have adhesiveness due to the formation of the resin coating layer 5, and can be adhered to a predetermined position by peeling the release film 3 at the time of use, and even when the surface of the sheet main body 2 has irregularities, the adhesion to an electronic component or a heat dissipating member can be improved by the resin coating layer 5.

[ Polymer base component ]

The polymer matrix component constituting the sheet main body 2 is a polymer component which is a base material of the thermal conductive sheet 1, the kind thereof is not particularly limited, and a known polymer matrix component can be appropriately selected, and for example, which is a polymer matrix component, a thermosetting polymer can be cited.

Examples of the thermosetting polymer include crosslinked rubbers, epoxy resins, polyimide resins, bismaleimide resins, benzocyclobutene resins, phenol resins, unsaturated polyesters, diallyl phthalate resins, silicone resins, polyurethanes, polyimide silicones, thermosetting polyphenylene ethers, thermosetting modified polyphenylene ethers, and the like. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

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, fluororubber, urethane rubber, acrylic rubber, polyisobutylene rubber, and silicone rubber. These may be used alone in 1 kind, or may be used in combination of 2 or more kinds.

Among these thermosetting polymers, silicone resins are preferably used in terms of excellent molding processability and weather resistance, and adhesion to electronic parts and conformability. The silicone resin is not particularly limited, and the type of the silicone resin may be appropriately selected according to the 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 heat vulcanization type kneading type silicone resin in which a peroxide is used for vulcanization, and the like. Among these, as a heat dissipating member of an electronic device, an addition reaction type liquid silicone resin is particularly preferable because adhesiveness between a heat generating surface of an electronic component and a heat sink surface is required.

As the addition reaction type liquid silicone resin, a two-pack type addition reaction type silicone resin or the like is preferably used, in which a polyorganosiloxane having a vinyl group is used as a main agent and a polyorganosiloxane having an Si — H group is used as a curing agent.

Here, the liquid silicone component has a silicone liquid a component as a main component and a silicone liquid B component containing a curing agent, and the amount of the silicone liquid a component is preferably not less than the amount of the silicone liquid B component as a blending ratio of the silicone liquid a component and the silicone liquid B component. Thus, the thermally conductive sheet 1 can impart flexibility to the sheet main body 2, and the uncured component of the binder resin (polymer matrix component) can be oozed out to the surfaces 2a and 2b of the sheet main body 2 by the pressing step to form the resin coating layer 5.

The content of the polymer matrix component in the thermally conductive sheet of the present invention is not particularly limited, and may be appropriately selected depending on the purpose, and is preferably about 15 to 50 vol%, more preferably 20 to 45 vol%, from the viewpoint of ensuring moldability of the sheet, adhesion of the sheet, and the like.

[ thermally conductive filler ]

The thermally conductive filler contained in the thermally conductive sheet 1 is a component for improving the thermal conductivity of the sheet. The kind of the thermally conductive filler is not particularly limited as long as it is a material having high thermal conductivity, and examples thereof include fibrous thermally conductive fillers such as carbon fibers, metals such as silver, copper, and aluminum, and ceramics such as alumina, aluminum nitride, silicon carbide, and graphite. Among these fibrous heat conductive fillers, carbon fibers are preferably used in order to obtain higher heat conductivity.

The thermally conductive fillers may be used singly in the form of kinds, or may be used in combination of two or more kinds.

The type of the carbon fiber is not particularly limited, and may be appropriately selected according to the purpose. For example, pitch-based carbon fibers, PAN-based carbon fibers, carbon fibers obtained by graphitizing PBO fibers, carbon fibers synthesized by arc discharge, laser evaporation, CVD (chemical vapor deposition), CCVD (catalytic chemical vapor deposition), or the like can be used. Among these, carbon fibers obtained by graphitizing PBO fibers and pitch-based carbon fibers are more preferable in terms of obtaining high thermal conductivity.

The carbon fibers may be partially or entirely surface-treated with as needed, and examples of the surface treatment include oxidation treatment, nitriding treatment, nitration treatment, sulfonation, and treatment in which a functional group introduced to the surface by the treatment or a carbon fiber surface is attached or bonded with a metal, a metal compound, an organic compound, or the like.

The average fiber length (average major axis length) of the carbon fibers is not particularly limited and may be appropriately selected at step , but is preferably in the range of 50 to 300 μm, more preferably in the range of 75 to 275 μm, and particularly preferably in the range of 90 to 250 μm, in order to reliably obtain high thermal conductivity.

The average fiber diameter (average minor axis length) of the carbon fibers may be appropriately selected without any particular limitation, and is preferably in the range of 4 to 20 μm, and more preferably in the range of 5 to 14 μm, from the viewpoint of reliably obtaining high thermal conductivity, further .

The aspect ratio (average major axis length/average minor axis length) of the carbon fiber is preferably 8 or more, and more preferably 9 to 30, from the viewpoint of reliably obtaining high thermal conductivity, and if the aspect ratio is less than 8, the fiber length (major axis length) of the carbon fiber is short, and therefore, there is a possibility that thermal conductivity is lowered, and if the aspect ratio exceeds 30, dispersibility in the thermally conductive sheet is lowered, and therefore, sufficient thermal conductivity may not be obtained, .

Here, the average major axis length and the average minor axis length of the carbon fiber may be measured by, for example, a microscope, a Scanning Electron Microscope (SEM), or the like, and an average value is calculated from a plurality of samples.

The content of the fibrous heat conductive filler in the heat conductive sheet 1 is not particularly limited and may be appropriately selected according to the purpose, and is preferably 4 to 40 vol%, more preferably 5 to 35 vol%. If the content is less than 4 vol%, it may be difficult to obtain a sufficiently low thermal resistance, and if it exceeds 40 vol%, the moldability of the thermal conductive sheet 1 and the orientation of the fibrous thermal conductive filler may be affected. The content of the thermally conductive filler containing the fibrous thermally conductive filler in the thermally conductive sheet 1 is preferably 15 to 75 vol%.

[ inorganic Filler ]

The thermally conductive sheet 1 may further contain an inorganic filler in the order of , and by containing an inorganic filler, the thermal conductivity of the thermally conductive sheet 1 can be further improved in the order of , and the strength of the sheet can be improved.

Examples of the material of the inorganic filler include aluminum nitride (AlN), silica, alumina (aluminum oxide), boron nitride, titanium dioxide, glass, zinc oxide, silicon carbide, silicon (silicon), silicon oxide, and metal particles, and kinds of these materials may be used alone or two or more kinds may be used in combination.

The inorganic filler may be surface-treated inorganic filler. 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 thermally conductive sheet is improved.

When the inorganic filler is alumina, the average particle diameter thereof is preferably 1 to 10 μm, more preferably 1 to 5 μm, and particularly preferably 4 to 5 μm, and if the average particle diameter is less than 1 μm, the viscosity may increase and the mixing may become difficult, and on the other hand, , if the average particle diameter exceeds 10 μm, the thermal resistance of the thermal conductive sheet 1 may increase.

Further , when the inorganic filler is aluminum nitride, the average particle diameter is preferably 0.3 to 6.0. mu.m, more preferably 0.3 to 2.0. mu.m, and particularly preferably 0.5 to 1.5. mu.m, and when the average particle diameter is less than 0.3. mu.m, the viscosity may become high and the mixing may become difficult, and when it exceeds 6.0. mu.m, the thermal resistance of the thermal conductive sheet 1 may become high.

The average particle diameter of the inorganic filler can be measured, for example, by a particle size distribution meter or a Scanning Electron Microscope (SEM).

[ other ingredients ]

The thermally conductive sheet 1 may contain other components as appropriate depending on the purpose, in addition to the polymer base component and the thermally conductive filler. Examples of the other components include magnetic metal powder, thixotropy imparting agent, dispersant, curing accelerator, retarder, micro-thickener, plasticizer, flame retardant, antioxidant, stabilizer, colorant, and the like. In addition, the electromagnetic wave absorption performance may be imparted to the thermal conductive sheet 1 by adjusting the content of the magnetic metal powder.

[ Process for producing thermally conductive sheet ]

[ Process A ]

Next, a process for producing the thermally conductive sheet 1 will be described. As described above, the process for producing the thermally conductive sheet 1 to which the present invention is applied includes the step a of forming a thermally conductive resin composition containing a thermally conductive filler in a binder resin into a predetermined shape and curing the composition to form a thermally conductive molded body.

In step a, the polymer matrix component, the thermally conductive filler, and other components contained as appropriate are blended to prepare a thermally conductive resin composition. The step of blending and preparing the respective components is not particularly limited, and for example, a thermally conductive filler, an appropriate inorganic filler, a magnetic metal powder, and other components are added to and mixed with a polymer matrix component to prepare a thermally conductive resin composition.

For example, by extruding or pressing the thermally conductive resin composition into a hollow mold under a high shear force, it is possible to relatively easily orient the fibrous thermally conductive filler in directions and to make the orientation of the fibrous thermally conductive filler the same (within ± 10 °).

As a method for extruding or pressing the thermally conductive resin composition into a hollow mold under high shear force, specifically, an extrusion molding method or a mold molding method can be mentioned. When the thermally conductive resin composition is extruded from a die in the extrusion molding method or when the thermally conductive resin composition is press-fitted into a mold in the mold molding method, the thermally conductive resin composition flows and the fibrous thermally conductive filler is oriented in the flow direction. At this time, if a slit is provided at the tip of the die, the fibrous heat-conductive filler is more easily oriented.

The thermally conductive resin composition extruded or press-fitted into a hollow mold is molded into a block shape corresponding to the shape and size of the mold, and the polymer matrix component is cured while maintaining the orientation state of the fibrous thermally conductive filler, thereby forming a thermally conductive molded body. The thermally conductive molded body is a sheet cutting base material (molded body) that is a raw material of the thermally conductive sheet 1 obtained by cutting into a predetermined size.

The size and shape of the hollow mold and the thermally conductive molded body can be determined according to the size and shape of the desired thermally conductive sheet 1, and examples thereof include a rectangular parallelepiped having a cross section with a longitudinal size of 0.5cm to 15cm and a lateral size of 0.5cm to 15 cm. The length of the rectangular parallelepiped can be determined as necessary.

For example, in the case where the polymer matrix component is a thermosetting resin, the curing temperature at the time of heat curing may be adjusted , and in the case where the thermosetting resin contains a main agent of a liquid silicone gel and a curing agent, the curing temperature is preferably 80 to 120 ℃.

In step a, the entire amount of the polymer matrix component is not cured, but an uncured component is carried. The uncured component penetrates the sheet surface in a pressing step of the molded body sheet under a reduced pressure environment described later, and forms an adhesive resin coating layer.

[ Process B ]

The manufacturing process of the thermally conductive sheet 1 to which the present invention is applied includes, as shown in fig. 2, a process B of cutting the thermally conductive molded body 6 into a sheet shape to form a molded body sheet 7. In step B, the thermally conductive resin molded body 6 is cut into a sheet shape so as to form an angle of 0 ° to 90 ° with respect to the longitudinal direction of the oriented fibrous thermally conductive filler.

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

The thickness of the molded sheet 7 is the thickness of the sheet main body of the thermal conductive sheet 1, and may be set as appropriate depending on the application of the thermal conductive sheet 1, and is, for example, 0.2mm to 1.0 mm.

In step B, the plurality of molded body sheets 7 may be formed into small pieces by applying cuts to the molded body sheets 7 cut out from the thermally conductive molded body 6.

[ Process C ]

The manufacturing process of the thermally conductive sheet 1 to which the present invention is applied includes a process C of coating the surface of the molded body sheet 7 with the uncured component of the binder resin that has oozed out from the sheet main body of the molded body sheet 7 by pressing the molded body sheet 7 in a reduced pressure environment.

The reduced pressure environment means a vacuum pressure that is lower than that in an atmosphere of normal pressure (atmospheric pressure) without any reduced pressure treatment and that is set to a pressure capable of allowing the uncured component of the binder resin to bleed out over the entire surface of the sheet surface, and the vacuum pressure can be appropriately set according to the thickness of the molded body sheet, the blending ratio of the silicone liquid a component that is the main agent of the liquid silicone component constituting the binder resin, and the silicone liquid B component that contains the curing agent, and the like. For example, the gauge pressure may be set to-0.2 kPa in a reduced pressure atmosphere, where the atmospheric pressure is set to zero. If the vacuum pressure x (kPa) in the pressing step is too low, uncured components in the binder resin volatilize to impair the tackiness of the sheet surface, and if too high, bleeding of the uncured components cannot be promoted, and for example, it is suitably set in the range of-5.0 kPa. ltoreq. x.ltoreq.0.1 kPa.

The pressing may be performed, for example, by using pairs of pressing devices each formed of a flat disk and a flat-surfaced press head.

The pressure at the time of pressing is not particularly limited and may be appropriately selected according to the purpose, and if too low, the resistance tends to be constant as compared with the case where pressing is not performed, and if too high, the sheet tends to be stretched, and therefore, the pressure is preferably in the range of 0.1MPa to 100MPa, and more preferably in the range of 0.5MPa to 95 MPa.

Here, as described above, in the thermally conductive molded article, not all of the polymer matrix component is cured, but the molded article sheet carries the uncured component of the binder resin (polymer matrix component) on the sheet main body, and portion of the uncured component is efficiently oozed out to the sheet surface through the pressing step in the reduced pressure environment, whereby the thermally conductive sheet 1 having the resin coating layer formed on the sheet surface can be formed, and the thermally conductive sheet 1 has adhesiveness due to the resin coating layer 5 formed on the sheet surface.

Further, by undergoing the pressing step, the surface of the molded body sheet is smoothed, whereby the adhesion of the heat conductive sheet 1 is enhanced, and the interface contact resistance under light load can be reduced.

As described above, according to the present invention, even from a sheet main body which is cut thinly and does not contain a large amount of uncured component containing a binder resin, the uncured component can be oozed out over the entire surface of the sheet surface to be coated. Further, even from the sheet main body which is hard and excellent in shape retention property by being cured with the binder resin and does not contain a large amount of uncured components containing the binder resin, the uncured components can be exuded over the entire surface of the sheet surface to be coated.

Therefore, the thermally conductive sheet produced by the present invention can improve the adhesion to electronic components and heat dissipating members and reduce the thermal resistance regardless of the irregularities on the sheet surface, and the thermally conductive sheet produced by the present invention does not require an adhesive agent for adhering the thermally conductive sheet to electronic components and heat dissipating members to be applied to the sheet surface, and the thermal resistance of the sheet does not increase, and is a step of providing a thermally conductive sheet containing a thermally conductive filler in a binder resin, which not only can reduce the thermal resistance from a low load region, but also has excellent adhesive force (adhesive force), and can improve the mountability and thermal characteristics.

[ Release film ]

In the step C, as shown in fig. 3, the release film 3 is preferably pressed in a state where the release film 3 is attached to at least surfaces, preferably both surfaces of the molded body sheet 7, and for example, a PET film is used as the release film 3, and the release film 3 may be subjected to a release treatment on the surface attached to the surface of the molded body sheet 7.

By attaching the release film 3 to the surface of the sheet main body of the molded body sheet 7, the uncured component that has oozed out to the sheet surface in the pressing step in the reduced pressure environment is held on the sheet surface by the tension acting between the release film 3 and the uncured component, and the resin coating layer 5 can be formed so as to be uniformly coated over the entire surface of the sheet surface with a uniform thickness. This eliminates variations in adhesion of the heat conductive sheet 1, and reduces thermal resistance.

Through the above steps, the thermal conductive sheet 1 is formed. In addition, the thermal conductive sheet 1 is provided with an adhesive resin coating layer 5 exposed by peeling the release film 3 during actual use, and is used for mounting to electronic components and the like.

[ example of use form ]

In actual use, the release film 3 of the thermal conductive sheet 1 is peeled off and mounted in an electronic component such as a semiconductor device or various electronic devices.

The heat conductive sheet 1 is mounted on a semiconductor device 50 built in various electronic devices, for example, as shown in fig. 4, and is sandwiched between a heat source and a heat dissipating member. The semiconductor device 50 shown in fig. 4 includes at least an electronic component 51, a heat spreader 52, and a thermal conductive sheet 1, and the thermal conductive sheet 1 is sandwiched between the heat spreader 52 and the electronic component 51. By using the heat conductive sheet 1, the semiconductor device 50 has high heat dissipation properties, and the electromagnetic wave suppression effect is also excellent 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 according to the purpose, and examples thereof include various semiconductor elements such as a CPU, an MPU, a graphic processing element, an image sensor, an antenna element, a battery, and the like, the heat equalizing sheet 52 is not particularly limited as long as it is a member that dissipates heat generated by the electronic component 51, and may be appropriately selected according to the purpose, the heat conductive sheet 1 is sandwiched between the heat equalizing sheet 52 and the electronic component 51, and the heat conductive sheet 1, by being sandwiched between the heat equalizing sheet 52 and the heat sink 53, constitutes a heat dissipating member that dissipates heat of the electronic component 51 together with the heat equalizing sheet 52 .

The mounting position of the heat conductive sheet 1 is not limited to between the heat equalizing sheet 52 and the electronic component 51 and between the heat equalizing sheet 52 and the heat sink 53, and may be appropriately selected depending on the configuration of the electronic device or the semiconductor device. The heat dissipating member may be any heat dissipating member other than the heat equalizing sheet 52 and the heat sink 53, which conducts and dissipates heat generated from a heat source to the outside, and examples thereof include a heat sink, a cooler, a chip holder, a printed circuit board, a cooling fan, a peltier element, a heat pipe, a metal cover (metalcover), and a case.