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 久保佑介 于 2019-07-11 设计创作，主要内容包括：本发明涉及导热性片的制造方法。本发明的课题是提供通过对导热性片的一面赋予粘着性,对另一面赋予非粘着性,从而提高作业性和再加工性的导热性片的制造方法。本发明的导热性片的制造方法包括下述工序：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,将导热性成型体切削成片状,形成成型体片的工序,在成型体片的两面粘贴剥离膜,将成型体片进行压制,从而利用从成型体片的片主体渗出的粘合剂树脂的未固化成分来被覆成型体片的两面,赋予粘着性的工序,从成型体片的一面剥离剥离膜,从一面除去粘合剂树脂的未固化成分,赋予非粘着性的工序,以及在一面粘贴新的剥离膜的工序。(A method for manufacturing a thermally conductive sheet, which improves workability and reworkability by imparting tackiness to the side of the thermally conductive sheet and imparting non-tackiness to the side of the thermally conductive sheet, includes 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 molded body, a step of cutting the thermally conductive molded body into a sheet shape to form a molded body sheet, a step of attaching release films to both sides of the molded body sheet, a step of coating both sides of the molded body sheet with uncured components of the binder resin that have oozed out from the sheet body of the molded body sheet by pressing the molded body sheet, a step of imparting tackiness to the molded body sheet, a step of peeling the release films from the side of the molded body sheet, a step of removing the uncured components of the binder resin from the side to impart non-tackiness to the molded body sheet, and a step of attaching a new release film to the side.)

A method for producing a thermally conductive sheet of the types 1 and , wherein the surface of the sheet main body has non-tackiness and the surface has tackiness, the method comprising the steps 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;

cutting the thermally conductive molded body into a sheet shape to form a molded body sheet;

a step of attaching release films to both surfaces of the molded body sheet, and pressing the molded body sheet so as to coat the both surfaces of the molded body sheet with uncured components of the binder resin that have oozed out from a sheet main body of the molded body sheet, thereby imparting tackiness to the both surfaces of the molded body sheet;

a step of peeling the release film from the surface of the molded body sheet, removing the uncured component of the binder resin from the surface, and imparting non-tackiness to the surface of the molded body sheet, and a step of

And a step of attaching a new release film to the surface from which the uncured component of the binder resin has been removed.

2. The method for producing a thermal conductive sheet according to claim 1, wherein after the release film is peeled from the side of the molded body sheet, the molded body sheet is left for a predetermined time under an atmospheric pressure atmosphere, thereby removing uncured components of the binder resin from the side of the molded body sheet.

3. The method for producing a thermally conductive sheet according to claim 1, wherein after the release film is peeled from the surface of the molded body sheet, the molded body sheet is left to stand in a heat-drying or reduced-pressure atmosphere, whereby uncured components of the binder resin are removed from the surface of the molded body sheet.

4. The method for producing a thermal conductive sheet according to any of claims 1 to 3, wherein a peel strength of the peel film attached to the surface is higher than a peel strength of the peel film attached to the surface.

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.

7. The method for producing the thermally conductive sheet according to any of claims 1 to 6, wherein the molded body sheet has a thickness of 0.2mm to 0.5 mm.

8. The method for producing a thermal conductive sheet according to of any one of claims 1 to 7, wherein the thermal conductive sheet having a circular shape with a diameter of 19mm and a thickness of 0.3mm is sandwiched by a cylindrical metal having a diameter of 20mm and a height of 12mm, and the thickness is adjusted so as to be 4.0kgf/cm²And then left standing at a temperature of 80 ℃ for 72 hours, wherein the distance of protrusion of the thermally conductive sheet from end faces of the cylindrical metal is 1.3mm or less.

Technical Field

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

Background

Along with the increase in performance of electronic devices, electronic components such as semiconductor elements have been increasingly densified and mounted in higher numbers, and heat conductive sheets used by being sandwiched between various heat sources (for example, various devices such as LSIs, CPUs, transistors, and LEDs) and heat dissipating members such as heat sinks (for example, heat dissipating fans and heat dissipating plates) have been used to efficiently dissipate heat generated from electronic components constituting electronic devices .

In addition, there is a limit to increase the filling ratio of the inorganic filler to be incorporated into the polymer matrix, however, if the filling ratio of the inorganic filler is increased, flexibility is impaired, or powder falling occurs due to the high filling ratio of the inorganic filler, and thus there is a limit to increase the filling ratio of the inorganic filler.

Examples of the inorganic filler include alumina, aluminum nitride, and aluminum hydroxide. For the purpose of high thermal conductivity, scaly particles such as boron nitride and graphite, and carbon fibers may be filled in the polymer matrix. This is because of anisotropy of thermal conductivity possessed by the scaly particles and the like. For example, in the case of carbon fibers, it is known that they have a thermal conductivity of about 600 to 1200W/mK in the fiber direction; in the case of boron nitride, the thermal conductivity is about 110W/mK in the plane direction, about 2W/mK in the direction perpendicular to the plane direction, and the anisotropy is exhibited. In this way, the surface direction of the carbon fibers and the flaky particles is the same as the thickness direction of the sheet as the heat transfer direction. That is, the carbon fibers and the flaky particles are oriented in the thickness direction of the sheet, whereby the heat conduction can be dramatically improved.

However, there are the following problems: when the resulting cured product is cut into a sheet, if the sheet cannot be cut to a uniform thickness, large uneven portions are formed on the surface of the heat conductive sheet, and when the sheet is sandwiched between an electronic component and a heat dissipation member, the uneven portions wind air, and excellent heat conduction cannot be performed.

Further, in the method of manufacturing a heat conductive sheet by cutting the heat conductive composition, there is a problem that the surface of the heat conductive sheet formed by cutting is not sticky (sticky).

Therefore, for example, in patent documents 1 and 2, high flexibility is provided by changing the ratio of the agent a and the agent B of the silicone, and a component not contributing to the reaction is exuded by pressing or sandwiching and standing in a PET film to provide tackiness, improve the follow-up property and adhesion to an adherend, and reduce thermal resistance. Further, since the heat conductive sheet has viscosity, the heat conductive sheet has workability and workability in assembling the electronic component and the heat sink.

Disclosure of Invention

Problems to be solved by the invention

Here, the heat conductive sheet is preferably a heat conductive sheet having a high adhesiveness on the side and a low adhesiveness on the other side, from the viewpoint of workability and workability, or from the viewpoint of reworkability such as correcting positional deviation when the electronic component and the heat dissipating member are assembled, or being disassembled for some reason after being temporarily assembled and then being able to be assembled again.

Therefore, it has been proposed to perform a non-sticking treatment on the surface of a thermally conductive sheet formed of a silicone rubber and a thermally conductive filler by ultraviolet irradiation (patent document 3).

Further, it has been proposed that in an adhesive heat conductive sheet in which an acrylic urethane resin is made to contain a nonfunctional acrylic polymer and a heat conductive filler, the adhesiveness of the front and back surfaces of the adhesive heat conductive sheet is made different by applying two layers of the acrylic urethane resin and the nonfunctional acrylic polymer in a superimposed manner at different mixing ratios of the acrylic urethane resin and the nonfunctional acrylic polymer in the front and back surfaces (patent document 4).

However, as described in patent document 3, if ultraviolet irradiation is performed to reduce the tackiness of the surface of the thermal conductive sheet, the layer that is responsible for thermal conductivity deteriorates.

Further, as described in patent document 4, when the acrylic urethane resin and the non-functional acrylic polymer are mixed at different blending ratios in the front surface layer and the back surface layer and are applied in a superposed manner, the front surface layer and the back surface layer are likely to be mixed, and it is difficult to change the adhesiveness between the front surface layer and the back surface layer as desired.

In addition, as a method of making the adhesiveness of the front surface and the back surface of the thermal conductive sheet different, in the case of forming an adhesive thermal conductive layer by using an acrylic resin and a thermal conductive filler, a method of laminating a non-adhesive film on the surface thereof is also considered, but in this case, the adhesiveness of the film surface to an article is extremely lowered, and thus the workability as a thermal conductive sheet is poor.

Accordingly, an object of the present invention is to provide a method for producing a thermally conductive sheet, in which workability and reworkability are improved by providing adhesiveness to side and non-adhesiveness to side of the thermally conductive sheet.

Means for solving the problems

In order to solve the above problems, a method for manufacturing a thermal conductive sheet according to the present invention is a method for manufacturing a thermal conductive sheet having a non-adhesive property on the side and an adhesive property on the side of a sheet main body, and includes a step of forming a thermal conductive molded body by molding a thermal conductive resin composition containing a thermal conductive filler in a binder resin into a predetermined shape and curing the molded body, a step of cutting the thermal conductive molded body into a sheet shape to form a molded body sheet, a step of attaching release films to both sides of the molded body sheet and pressing the molded body sheet so that both sides of the molded body sheet are covered with uncured components of the binder resin that have oozed out of a sheet main body of the molded body sheet and adhesion is provided to both sides of the molded body sheet, a step of peeling the release films from the side of the molded body sheet and removing uncured components of the binder resin from the side and providing a non-adhesive property to the side of the molded body sheet, and a step of attaching a new release film to the side from which the uncured components of the binder resin have been removed.

ADVANTAGEOUS EFFECTS OF INVENTION

According to the present invention, a thermally conductive sheet having a non-adhesive side and an adhesive side of a sheet main body can be produced, which is improved in workability and reworkability and has excellent handleability.

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.

Fig. 4 is a sectional view showing a step of forming a resin coating layer between the surface of the bonded molded body sheet and the release film.

Fig. 5 is a sectional view showing a step of removing the 3 rd release film from surfaces of the molded body sheet.

Fig. 6 is a cross-sectional view showing a state where uncured components are removed from surfaces of a molded body sheet.

Fig. 7 is a cross-sectional view of examples showing a semiconductor device.

Description of the symbols

1 thermally conductive sheet, 2 main bodies, 3 st release film, 1 st release film, 4 nd release film, 5 resin coating layer, 6 thermally conductive molded body, 7 molded body sheet, 8 rd release film.

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.

A method for manufacturing a thermal conductive sheet to which the present invention is applied is a method for manufacturing a thermal conductive sheet having a sheet main body with an surface having non-tackiness and an surface having tackiness, and includes a step (step A) of forming a thermal conductive molded body by molding a thermal conductive resin composition containing a thermal conductive filler in a binder resin into a predetermined shape and curing the molded body, a step (step B) of cutting the thermal conductive molded body into a sheet shape to form a molded body sheet, a step (step C) of attaching a release film to both surfaces of the molded body sheet and pressing the molded body sheet so that both surfaces of the molded body sheet are covered with uncured components of the binder resin that have oozed out of the sheet main body of the molded body sheet and tackiness is given to both surfaces of the molded body sheet, a step (step D) of releasing the release film from the surface of the molded body sheet, removing uncured components of the binder resin from the surface and giving non-tackiness to the surface of the molded body sheet, and a step (E) of releasing a new release film from which uncured components of the binder resin have been removed (step E ).

The heat conductive sheet produced through the above steps carries an uncured component that does not contribute to the reaction of the binder resin on the sheet main body of the molded sheet, and the portion of the uncured component is forcedly oozed out to the sheet surface through the pressing step.

It is presumed that, if the release films are removed from surfaces of the sheet main body from this state, uncured components covering surfaces disappear and non-tackiness is exhibited, because the uncured components which have been forcibly oozed out by the pressing step and held between the release films are returned into the sheet main body by removing the release films.

The thermal conductive sheet manufactured through the above process has non-tackiness on the side and tackiness on the side of the sheet main body, and thus workability, handling properties, and reworkability are improved.

[ constitution of thermally conductive sheet ]

Fig. 1 shows a thermal conductive sheet 1 to which the present invention is applied, the thermal conductive sheet 1 having a sheet main body 2 obtained by curing a binder resin containing at least a polymer matrix component and a thermal conductive filler, a 1 st release film 3 adhered to an -side 2a of the sheet main body 2, a 2 nd release film 4 adhered to another -side 2b of the sheet main body 2, and a resin coating layer 5 formed by coating uncured components of the binder resin oozing from the sheet main body 2.

The side 2a of the thermal conductive sheet 1 has non-adhesiveness and maintains non-adhesiveness even after the 1 st release film 3 is peeled off, and the other side 2b of the thermal conductive sheet 1 has adhesiveness by forming the resin coating layer 5, and can be adhered to a predetermined position by peeling off the 2 nd release film when in use.

This makes it possible to provide the thermal conductive sheet 1 having excellent reworkability such as correction of positional deviation when the electronic component and the heat dissipating member are assembled, or disassembly for some reason after temporary assembly, and re-assembly, and having the face 2a provided with non-tackiness, thereby providing excellent workability and workability.

[ 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 silicone liquid a component is preferably contained in an amount equal to or greater 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, whereby the thermal conductive sheet 1 can impart flexibility to the sheet main body 2, and cause uncured components of the binder resin (polymer matrix component) to bleed out to the surfaces 2a, 2B of the sheet main body 2 through the pressing step, and the resin coating layer 5 is formed between the other surfaces 2B and the 2 nd release film 4.

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 concern that the thermal conductivity is lowered, and if it exceeds 30, the dispersibility in the thermal conductive sheet is lowered, and therefore there is a concern that sufficient thermal conductivity cannot 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 thermal conductive filler containing the fibrous thermal conductive filler in the thermal 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, the fibrous thermal conductive filler can be relatively easily oriented in directions by extruding or pressing the thermal conductive resin composition into a hollow mold under a high shear force, and the orientation of the fibrous thermal conductive filler can be made 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 the pressing step of the molded body sheet described later, and forms a resin coating layer having adhesiveness.

[ 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 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 2 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 0.5 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 ]

As shown in fig. 3, the manufacturing process of the thermal conductive sheet 1 to which the present invention is applied includes a process C of attaching the 3 rd release film 8 to the side of the molded body sheet 7, attaching the 2 nd release film 4 to the side of the molded body sheet 7, and pressing the molded body sheet 7 to coat both sides of the molded body sheet 7 with uncured components of the binder resin that have oozed out from the sheet main body of the molded body sheet 7, thereby imparting adhesiveness to both sides of the molded body sheet 7.

For example, PET films are used as the 2 nd and 3 rd release films 4 and 8. The 2 nd and 3 rd release films 4 and 8 may be subjected to a peeling treatment on the adhesion surface facing the surface of the molded body sheet 7.

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 thermal resistance tends to be unchanged 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 body 6, not all of the amount of the polymer matrix component is cured, but the uncured component of the binder resin (polymer matrix component) is carried by the sheet main body of the molded body sheet 7, and as shown in fig. 4, part of the uncured component is forcedly oozed out to the sheet surface by the pressing step, the uncured component oozed out to the sheet surface is held on the sheet surface by the tension acting between the 2 nd release film 4 and the 3 rd release film 8, and the resin coating layer 5 is formed to coat the entire surface of the sheet with a uniform thickness, thereby imparting adhesiveness to the sheet surface.

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

[ Process D ]

As shown in fig. 5 and 6, the manufacturing process of the thermal conductive sheet 1 to which the present invention is applied includes a process D of peeling the 3 rd release film 8 from the surface of the molded body sheet 7, removing uncured components of the binder resin from the surface, and imparting non-tackiness to the surface of the molded body sheet.

In the molded body sheet 7, if the 3 rd release film 8 is removed from the side of the sheet main body, the uncured component covering the surfaces disappears and non-tackiness is exhibited, and this is presumably because the removal of the 3 rd release film 8 causes the uncured component which has been forcibly oozed out by the pressing step and held between the 3 rd release film 8 and the sheet main body to return to the sheet main body.

After the 3 rd release film 8 is peeled off, the molded body sheet 7 is left standing at room temperature under an atmospheric pressure atmosphere until the uncured component disappears from the surface, and further, after the 3 rd release film 8 is peeled off, a predetermined time, for example, several minutes to several tens of minutes is required until the uncured component disappears from the surface, and this varies depending on the amount of the polymer matrix component constituting the uncured component, the uncured component exuded to the surface, and the like.

In the step D, the uncured component of the binder resin may be removed from the surface of the molded body sheet 7 by leaving the molded body sheet 7 in a state heated and dried in an oven, an industrial dryer, or the like, or by leaving the molded body sheet 7 in a reduced pressure atmosphere, or by leaving the molded body sheet 7 in an environment using both of them.

The peel strength of the 3 rd release film 8 attached to the side may be made higher than the peel strength of the 2 nd release film 4 attached to the side the uncured component oozing out to the side is a component that disappears or is removed, the necessity of the 3 rd release film 8 for the peeling treatment is low, and the peel strength may be made higher than the 2 nd release film 4 attached to the side.

[ Process E ]

The process for producing the thermal conductive sheet 1 to which the present invention is applied includes a step E of attaching a 1 st release film 3 different from the 3 rd release film 8 to the side of the molded sheet from which uncured components of the binder resin have been removed, whereby the thermal conductive sheet 1 is formed such that the side 2a of the sheet main body 2 has non-tackiness and the side 2b has tackiness, as shown in fig. 1.

Since the thermal conductive sheet 1 does not bleed uncured components of the binder resin on surfaces 2a even after peeling the 1 st release film 3, and maintains non-tackiness, the thermal conductive sheet 1 manufactured through the above-described steps has non-tackiness on the surface 2a and tackiness on the surface 2b of the sheet main body 2, and workability, and reworkability can be improved.

[ example of use form ]

In actual use, the thermal conductive sheet 1 is peeled off the 1 st and 2 nd release films and mounted in electronic components such as semiconductor devices and various electronic devices, for example, in this case, the face 2a of the sheet main body 2 of the thermal conductive sheet 1 is given non-adhesiveness and the face 2b is given adhesiveness, so that the workability is excellent, and the reworkability is also excellent, such as correction of positional deviation at the time of assembly of the electronic component and the heat dissipating member, or disassembly and reassembly for some reason after temporary assembly is excellent.

The heat conductive sheet 1 is mounted on a semiconductor device 50 built in various electronic devices, for example, as shown in fig. 7, and is sandwiched between a heat source and a heat dissipating member. The semiconductor device 50 shown in fig. 7 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 thermal 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.

[ shape Retention and reliability ]

In addition, it is required that the thermal conductive sheet 1 maintains its shape when the 1 st and 2 nd release films 3 and 4 are peeled off and is held between an electronic component and a heat dissipation member in actual use, so that creep behavior is suppressed even in a high-temperature environment where constant load is applied, and long-term reliability is obtained.

Therefore, the flexibility of the sheet main body 2 in a high-temperature environment to which a constant load of is applied can be set by appropriately adjusting the blending ratio of the silicone liquid a component and the silicone liquid B component of the binder resin for the thermally conductive sheet 1.

For example, a circular thermal conductive sheet 1 having a diameter of 20mm and a thickness of 0.3mm is held by a cylindrical jig having a diameter of 20mm and a height of 12mm, and adjusted so as to be applied at 4.0kgf/cm²After the load, the thermal conductive sheet 1 was left standing at a temperature of 80 ℃ for 72 hours, and the distance by which it protruded from end faces of the jig was 1.3mm or less, which is 5% or less of the diameter (20mm) of the cylindrical jig.

Thus, the thermal conductive sheet 1 can maintain its shape without being stretched, deformed, or even broken by the release films 3 and 4 when the 1 st release film 3 and the 2 nd release film 4 are peeled off in actual use, and the thermal conductive sheet 1 can suppress creep behavior in a high-temperature environment in which constant load is applied, and maintain long-term reliability.