JP2011056618A - Manufacturing method for thermally conductive sheet, and thermally conductive sheet - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a technology, for a thermally conductive sheet to be interposed between a heating element and a heat dissipator, which makes its side surfaces hard to stick to each other, thereby improving its shape preservation and handling. <P>SOLUTION: When each prescribed size of thermally conductive sheet 11 is cut from a large-sized sheetlike body 18, a film forming agent 16 is attached to a cutting blade 4 for cutting and curing, thereby forming the thermally conductive sheet 11 having a nonviscous elastic film 14a on a side surface as a cutting surface. The thermally conductive sheet 11 is hardly deformed and excellent in handling as it has the side surface made of the nonviscous elastic film 14a. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a heat conductive sheet and a heat conductive sheet which are fixed to a heat generating electronic component and used as a heat countermeasure member for heat dissipation and cooling of the electronic component.

  ICs and CPUs mounted on electronic devices are electronic components that generate heat during use (during execution). In order to cool electronic components of such heating elements, heat sinks, heat pipes, etc. are provided inside the electronic devices. It is equipped with a radiator. And in order to accelerate | stimulate the heat conduction from a heat generating body to a heat radiator, the heat conductive sheet is interposed between the heat generating body and the heat radiator. By using this heat conductive sheet, the heat transfer area between the heat generating body and the heat radiating body is increased, and heat can be efficiently released from the heat generating body to the heat radiating body.

  The heat conductive sheet increases the heat conductivity by improving the followability and adhesion to an adherend such as a heating element and a heat radiating body. For this reason, the thermal conductive sheet is required to have flexibility, but as the flexibility increases, the adhesiveness also increases. When the adhesiveness increases, the thermal conductive sheets stick to each other, and the attachment work to the adherend becomes difficult. Sometimes it becomes. Further, if the wall thickness is reduced, the thermal conductivity can be improved, but if it is made thinner, there is a disadvantage that it is easily broken and the handleability is deteriorated.

As a countermeasure against the above problems, for example, Japanese Patent Laid-Open No. 02-196453 (Patent Document 1) discloses a first silicone resin layer that is soft and easily deformed, and a second silicone resin having a strength necessary for handling. A thermally conductive sheet composite in which layers are laminated is disclosed. Japanese Patent Application Laid-Open No. 10-183110 (Patent Document 2) discloses a thermally conductive silicone gel molded sheet in which a silicone gel layer containing a thermally conductive filler and a thin film reinforcing layer cured in a rubber shape are laminated. Has been. Furthermore, Japanese Patent Application Laid-Open No. 11-307697 (Patent Document 3) discloses a silicone rubber layer A containing a thermally conductive filler, having a Shore A hardness of 20 or more and excellent in tensile strength, non-adhesiveness, and reinforcing properties, A thermally conductive composite sheet containing a conductive filler and laminated with a silicone rubber layer B having an Asker C hardness of 30 or less is disclosed.
Such a heat conductive sheet is formed according to the size of an adherend after a large sheet body, which is a heat conductive sheet formed in a large size compared to a full-size heat conductive sheet, is formed on a resin film. A manufacturing method of cutting into a desired size is adopted, and the cut large-sized sheet is placed on a resin film and shipped to a mounting factory.

Japanese Patent Laid-Open No. 02-196453 JP-A-10-183110 Japanese Patent Laid-Open No. 11-307697

  However, although the large sheet body is divided into individual heat conductive sheets, it is easy to re-adhere the cut surfaces of adjacent heat conductive sheets by being pressurized during packing and transportation, and resin film during mounting There is a problem that it is difficult to remove the thermal conductive sheets one by one. Furthermore, since the heat conductive sheet is thin, there is a problem that if it is peeled off from the resin film while the cut surfaces are adhered to each other, the sheet is stretched and deformed or broken.

  The present invention has been made against the background of the prior art as described above. That is, an object of the present invention is to obtain a heat conductive sheet excellent in handleability that is easy to be peeled off from a base film and mounted easily.

  In order to achieve the above object, a method for producing a heat conductive sheet in which a heat conductive filler is dispersed in a polymer base material, a heat conductive composition in which the heat conductive filler is blended with the polymer base material is desired. Cut the large sheet body by cutting the large sheet body into the direction of crossing the surface of the large sheet body. A step of attaching a film forming agent to the cut surface and a step of curing the film forming agent adhering to the cut surface to form a non-adhesive elastic film on the cut surface in the thickness direction. Provided is a method for producing a heat conductive sheet, wherein a heat conductive sheet having a non-adhesive elastic film is formed on a side surface along the side surface.

About the manufacturing method of the heat conductive sheet which a heat conductive filler disperse | distributes in a polymer base material, the heat conductive composition which mix | blended the heat conductive filler with the polymer base material is larger than desired size sheet form Since the step of forming the large sheet body formed in the above is provided, a plurality of thermally conductive sheets can be manufactured simultaneously.
In addition, the cutting blade coated with the film forming agent is inserted in the cross direction with respect to the surface of the large sheet body, and the cutting process is performed by cutting the large sheet body and attaching the film forming agent to the cut surface. A film forming agent can be easily adhered to the cut surface obtained by inserting the blade, and a non-adhesive elastic film can be easily formed on the cut surface. Then, by cutting with a cutting blade, the cutting of the large sheet body and the attachment of the film forming agent can be carried out simultaneously, and the cutting and the attachment of the film forming agent can be carried out separately. Furthermore, since the film forming agent is attached with the cutting blade, the film forming agent can be attached to the entire surface of the cut surface of the large sheet body without leakage, and the film forming agent can be uniformly attached to the cut surface. .
Furthermore, since a step of forming a non-adhesive elastic film on the cut surface by reacting the film forming agent adhering to the cut surface is provided, a non-adhesive elastic film is formed on the side surface of the heat conductive sheet having a desired size. Can be provided. The heat conductive sheet having the non-adhesive elastic film on the side surface hardly adheres to the side surfaces of adjacent heat conductive sheets, and the workability in mounting the heat conductive sheet is improved.

In the process of attaching the film-forming agent, the first cutting process in which a cutting blade not coated with the film-forming agent is inserted into a large sheet body, and the cutting blade coated with the film-forming agent is inserted in the same place and cut. A second cutting step of attaching a film forming agent to the substrate.
A first cutting process in which a cutting blade not coated with a film forming agent is inserted into a large sheet body, and a second cutting blade coated with a film forming agent is inserted in the same place to attach the film forming agent to the cut surface. Since the next cutting step is provided, the cutting of the large sheet body and the application of the film forming agent can be performed as separate steps in the first cutting step and the second cutting step. Thereby, adhesion of the film forming agent to the cut surface can be performed more precisely. In addition, the primary cutting process is a temporary cutting process in which a cut is made without completely cutting, and the second cutting process is a main cutting that completely cuts a large sheet, and the adhesion of a film forming agent to the cut surface It can also be set as the process of performing. Furthermore, the cutting blades used in the first cutting step and the second cutting step can be the same cutting blade or different cutting blades. If the same cutting blade is used, the types of cutting blades to be prepared are reduced, which is efficient, and the cutting and coating of the film forming agent can be performed with the same cutting blade. On the other hand, if another cutting blade is used, a cutting blade having a shape more suitable for each step of cutting and coating of the film forming agent can be appropriately selected.

Also provided is a thermally conductive sheet in which a thermally conductive filler is dispersed in a polymer substrate, and having a non-adhesive elastic film on a side surface along the thickness direction.
Since the heat conductive sheet has a non-adhesive elastic film on the side surface along the thickness direction, even if a plurality of heat conductive sheets are in contact with each other, it is difficult to stick to each other. The handleability of the conductive sheet can be facilitated.
In addition, even if the inside of the heat conductive sheet is easily compressed such as a gel, clay, or paste, the sheet shape can be held by the side surface on which the elastic film is formed. It is an excellent thermal conductive sheet.

About this heat conductive sheet, the heat conductive sheet which is a reaction film of the hardening agent contained in the film forming agent adhering to the side surface along the thickness direction and the base material forming the polymer substrate. It can be.
Non-adhesive formed on the side surface of the heat conductive sheet because the elastic film is a reaction film between the curing agent contained in the film forming agent attached to the side surface along the thickness direction and the base material forming the polymer substrate. It is possible to obtain a heat conductive sheet whose properties gradually change from the side surface to the inside without forming a clear interface between the adhesive elastic film and the sticky part inside the heat conductive sheet. Therefore, the elastic film is hardly peeled off. In addition, rapid changes in flexibility, thermal conductivity, and other properties between the side surface and the inside can be suppressed.

And about this heat conductive sheet, an elastic film can be made into the heat conductive sheet which has the repulsive force with respect to the compression to thickness direction.
Since the elastic film is a heat conductive sheet that has a repulsive force (elasticity) against compression in the thickness direction, the inside of the heat conductive sheet is in the form of gel, clay, paste, etc. Even if it does not have a typical restoring force, it has a fixed shape and is excellent in dimensional stability. It can also be reused once it has been compressed.

Furthermore, the present invention provides a heat conductive sheet having a non-adhesive elastic film on at least one of the front surface and the back surface intersecting in the thickness direction.
Since the non-adhesive elastic film is provided on at least one of the front surface and the back surface that intersects the thickness direction, the front surface or the back surface that intersects the thickness direction can also be made non-adhesive, and handleability is improved. In other words, it is possible to combine a soft interior such as an amorphous clayey or paste and a hard surface or back such as a fixed gel or rubber, the surface side is a fixed layer and the inner surface is amorphous By using a layer, it is possible to realize a heat conductive sheet that has a small compressive load and is excellent in shape retention and easy to handle.

The heat conductive sheet according to claim 6, wherein any one of the elastic films has a hardness different from that of the other elastic films.
Since any one of the elastic films is an elastic film having a hardness different from that of the other elastic films,
A flexible design can be made according to the application site of the heat conductive sheet. That is, for example, the front side is soft in order to increase the contact area with the heating element, and the back side is not so soft, and if the hardness is required from the viewpoint of handling, the front side is soft and the back side is soft. It can be formed hard.

  The non-adhesive elastic film provided on the side surface of the heat conductive sheet can be intermittently formed on a part of the side surface in addition to the case where it is provided on the entire side surface. Since the side surface portion on which the elastic film is not formed easily bulges outward when subjected to a compressive force, the compression load can be reduced as compared with the case where the entire side surface is made of an elastic film.

According to the method for producing a heat conductive sheet of the present invention, the film forming agent can be efficiently applied without slipping to the side surface along the thickness direction of the heat conductive sheet. And the high quality heat conductive sheet with a good yield can be obtained.
In addition, according to the heat conductive sheet of the present invention, the non-adhesive elastic film is provided on the side surface along the thickness direction, and the side surfaces of the heat conductive sheet are difficult to stick to each other. can do. Further, since the side surface is hard and has a fixed formability, it is excellent in handling in mounting on an electronic device. Furthermore, the inside is soft and the contact area can be increased, and the thermal resistance is low. In addition, it has a repulsive force despite its soft interior and low load value, and has excellent formability (shape retention) and handling.

The top view which shows the heat conductive sheet of 1st Embodiment. FIG. 3 is a sectional view taken along line SA-SA in FIG. 1. Explanatory drawing when it is a manufacturing method in the heat conductive sheet of 1st Embodiment, and forms a large format sheet body with a heat conductive composition. Explanatory drawing when it is a manufacturing method in the heat conductive sheet of 1st Embodiment, and cuts a large format sheet body first. Explanatory drawing when it is a manufacturing method in the heat conductive sheet of 1st Embodiment, and cuts a large-sized sheet body secondarily. Explanatory drawing after cut | disconnecting the large format sheet | seat body, which is a manufacturing method in the heat conductive sheet of 1st Embodiment. The perspective view which shows the manufacturing method in the heat conductive sheet of 1st Embodiment, and shows the sheet | seat arranged on the resin film. Sectional drawing equivalent to FIG. 2 which shows the heat conductive sheet of 2nd Embodiment. Explanatory drawing when it is a manufacturing method in the heat conductive sheet of 2nd Embodiment, and heat-conductive composition with high hardness is made into a sheet. Explanatory drawing when it is a manufacturing method in the heat conductive sheet of 2nd Embodiment, and forms a large sheet body by making the heat conductive composition with low hardness into a sheet. Sectional drawing equivalent to FIG. 2 which shows the heat conductive sheet of 3rd Embodiment. Explanatory drawing when it is a manufacturing method in the heat conductive sheet of 3rd Embodiment, and laminates what formed the heat conductive composition with high hardness into a sheet, and forms a large sheet body. The top view which shows the modification common to the heat conductive sheet of each embodiment.

  The present invention will be described in more detail based on the following embodiments. In addition, about the structure which is common in each embodiment, the same code | symbol is attached | subjected and duplication description is abbreviate | omitted. In addition, duplicate descriptions of common materials, functions, effects, and the like are omitted.

First Embodiment (FIGS. 1 to 7) :
The heat conductive sheet 11 of this embodiment and its manufacturing method are shown in FIGS. 1 is a plan view of the heat conductive sheet 11, FIG. 2 is a sectional view taken along the line SA-SA of the heat conductive sheet 11, and FIGS. 3 to 7 are explanatory views showing a method for manufacturing the heat conductive sheet 11. FIG. .

The heat conductive sheet 11 is a component for an electronic device having good adhesion to a heat generator such as an IC or a CPU, or a heat sink such as a heat sink or a heat pipe. As shown in FIGS. The adhesive body 13 formed in a rectangular sheet shape is composed of a heat conductor 12 having a non-adhesive elastic film 14a formed on the side surface.
The adhesive body 13 is formed of a polymer base material in which a heat conductive filler is dispersed so that the adhesive body 13 has good adhesion to a heat generator and a heat radiator and can easily conduct heat. The elastic film (side elastic film) 14 a formed on the side surface is more elastic and harder than the adhesive body 13 and is non-adhesive.
“Non-adhesive” refers to a property in which the side elastic coatings 14a are not easily adhered when they are brought into contact with each other without being pressurized, and is difficult to adhere even when touched by an operator's hand. In addition, it refers to the property of being easily peeled off even if it is applied under pressure. The adhesive body 13 in which the side elastic film 14a is not formed has adhesiveness that adheres to each other when the heat conductive sheets 11 are brought into contact with each other without being pressurized, but there is no such adhesiveness. It is the concept which shows.

  The heat conductor 12 is preferably softer so that the contact area between the heat conductor 12 and the heating element becomes larger because the heat radiation area becomes wider as the contact area with the heating element becomes larger. The lower the load value at the time of contact, the wider the contact area and the less the pressing force against other electronic components, so the smaller the repulsive force against the press, the better. From this point of view, the polymer base material forming the adhesive body 13 is made of a material having a type E hardness (hereinafter simply referred to as “E hardness”) defined by JIS K 6253 at the time of receiving a load of 60 or less. It is preferable to use it. When the E hardness exceeds 60, the heat conductor 12 loses its flexibility and becomes hard, and the adhesion to the heating element and the like deteriorates. This is because the contact area between the heat conductive sheet 11 and the heating element becomes narrow, and sufficient heat conductivity may not be obtained. On the other hand, a low-hardness gel-like, clay-like, or paste-like material having an E hardness of 0 or less is preferable because adhesion to a heating element and the like can be improved and heat conduction performance can be improved. For the polymer base material whose E hardness can be 0 or less, a material having an immiscibility penetration of 1 to 100 measured using a ¼ cone based on JIS K 2220 can be used.

  For such a polymer substrate, a polymer material such as a thermoplastic elastomer or a thermosetting elastomer can be used. The thermoplastic elastomer includes styrene-butadiene block copolymer and hydrogenated polymer thereof, styrene-isoprene block copolymer and hydrogenated polymer thereof, styrene thermoplastic elastomer, olefin thermoplastic elastomer, vinyl chloride thermoplastic elastomer. Polyester thermoplastic elastomer, polyurethane thermoplastic elastomer, polyamide thermoplastic elastomer, and the like. Thermosetting elastomers include natural rubber, silicone rubber, acrylic rubber, butadiene rubber, isoprene rubber, styrene-butadiene copolymer rubber, nitrile rubber, hydrogenated nitrile rubber, chloroprene rubber, ethylene-propylene copolymer rubber, chlorinated polyethylene. Examples thereof include rubber, chlorosulfonated polyethylene rubber, butyl rubber, fluorine rubber, and urethane rubber.

Further, such a polymer base material can be produced from a mixed system such as a main agent and a curing agent which are cured after being mixed and become the polymer material. For example, it can be an uncrosslinked rubber and a crosslinking agent, or it can be an uncrosslinked rubber containing a crosslinking agent and a crosslinking accelerator, and the curing reaction can be room temperature curing or heat curing. . Examples of the silicone rubber include silicone rubber main ingredients and curing agents, such as vinyl group-containing silicone raw rubber and peroxide. In addition, a diol and a dicarboxylic acid can be used for a polyester-based thermoplastic elastomer or a polyamide-based thermoplastic elastomer, and a diisocyanate and a diol can be used for a polyurethane-based thermoplastic elastomer. Here, one of at least two components before mixing is referred to as a main agent and the other is referred to as a curing agent, and either of them may be defined as a main agent or a curing agent. Therefore, for example, the smaller mixing ratio and the lower viscosity may be used as the main agent.
Furthermore, the polymer base material may be only the main agent that does not contain a curing agent among such a main agent and a curing agent.

  As these polymer base materials, or the main agent and the curing agent, those containing various additives for the purpose of enhancing various properties such as productivity, weather resistance, and heat resistance of the heat conductive sheet 11 can be used. . Examples of such additives include various functional improvers such as plasticizers, reinforcing materials, colorants, heat resistance improvers, coupling agents, flame retardants, adhesives, catalysts, cure retarders, and deterioration inhibitors. It is done.

  Examples of the thermally conductive filler dispersed in the polymer base material to impart thermal conductivity to the thermal conductor 12 include metal oxide, metal nitride, metal carbide, metal hydroxide, and carbon fiber. Fine powder consisting of Examples of the metal oxide include aluminum oxide, magnesium oxide, zinc oxide, and quartz, and examples of the metal nitride include boron nitride and aluminum nitride. Examples of the metal carbide include silicon carbide, and examples of the metal hydroxide include aluminum hydroxide. Further, examples of carbon fibers include pitch-based carbon fibers, PAN-based carbon fibers, fibers obtained by carbonizing resin fibers, fibers obtained by graphitizing resin fibers, and the like. Such a heat conductive filler can be oriented in a certain direction with respect to the heat conductor 12, and the orientation is preferable in terms of increasing the heat conductivity.

The side elastic film 14a is a part of the heat conductor 12, but has a repulsive force (elasticity) and is a hard part as compared with the adhesive body 13 in which the side elastic film 14a is not formed. In this embodiment, it is formed on the four side surfaces of the heat conductive sheet 11, suppresses the adhesiveness inside the heat conductive sheet 11, and improves the hardness, thereby improving the formability and handling of the heat conductive sheet 11. Increases sex.
The side elastic film 14 a is obtained by curing the film forming agent attached to the side surface of the adhesive body 13. Therefore, it is possible to use a material that has high adhesion to the adhesive body 13 and has higher hardness than the adhesive body 13. The following materials can be used for such a film forming agent.

(1) Adhesive As the film forming agent, first, an adhesive having adhesiveness to the polymer substrate can be used.
As the adhesive, an adhesive that has adhesiveness to the adhesive body 13 and can be cured can be used. For example, one of silicone, urethane, epoxy, phenol, polyimide, thermoplastic, and the like can be used. Various adhesives such as a liquid curing type, a two-component curing type, a UV curing type, and a thermosetting type can be used.

(2) Mixed composition of main agent and curing agent Next, a composition containing the main agent that becomes the polymer substrate of the pressure-sensitive adhesive body 13 and a curing agent that reacts and cures with the main agent can be used as a film forming agent. . For example, the adhesive body 13 is formed of a main agent and a curing agent that are thermally cured to become a polymer base material, and a film forming agent that is a mixed composition of the main agent and the curing agent is applied to the side surface of the adhesive body 13. By heating, the adhesive body 13 in which the main agent and the curing agent are crosslinked and cured can be formed, and the side elastic film 14a in which the same main agent and the curing agent are crosslinked and cured can be formed. In this case, since the adhesive body 13 and the side elastic film 14a are made of the same material, the adhesive force at the interface between the adhesive body 13 and the side elastic film 14a is strong. When the content ratio of the main agent and the curing agent is compared between the adhesive body 13 and the side elastic film 14a, the side elastic film 14a has a higher content of the curing agent.

(3) Curing Agent Further, the side elastic film 14a can be a curing agent itself that reacts with the main agent that becomes the polymer base material of the adhesive body 13 and cures.
When the side elastic film 14a is formed using only the curing agent not containing the main agent as a film forming agent, there is no clear boundary between the adhesive body 13 and the side elastic film 14a, and the heat gradually hardens from the inside toward the side. The conductor 12 can be obtained. Therefore, the boundary part between the adhesive body 13 and the side elastic film 14a uses a boundary surface based on a different material when the adhesive of the above (1) is used, and a mixed composition of the main agent and the curing agent of the above (2). In the case of the same kind of material, it is different from the fact that a boundary surface based on the difference in hardness is generated.
That is, when a curing agent is used as the film forming agent, the curing agent penetrates into the adhesive body 13 to form the side elastic film 14a, so there is no boundary between the adhesive body 13 and the side elastic film 14a. Since it is integrated, the side surface is difficult to peel off. In other words, since the gradient material gradually develops adhesiveness from the outer edge to the inner side, the side elastic film 14 a also becomes a part of the adhesive body 13. In this respect, it is preferable to use the curing agent as a film forming agent.

  Therefore, if the description of the drawings is supplemented, in FIG. 1 and FIG. 2, the solid line is displayed so that there is an interface between the elastic film 14 a and the adhesive body 13, but it reacts with the base of the adhesive body 13. In the case of the above (3) in which the elastic film 14a is formed with a film forming agent made of a curing agent, such a clear interface does not actually exist.

  In the case of the above (2) and (3), the amount of the curing agent added to the adhesive body 13 and the amount of the curing agent attached to the side surface of the adhesive body 13, or the type of these curing agents, and in some cases, included in the film forming agent. By adjusting the amount of the main agent, the hardness and repulsive force of the adhesive body 13 and the side elastic film 14a can be adjusted.

The adhesion amount of the film forming agent is preferably 5 μm to 20 μm in thickness. This is because when the thickness is in the range of 5 μm to 20 μm, the side elastic film 14 a having a relatively uniform thickness can be provided on the side surface of the adhesive body 13, and the side elastic film 14 a can be set to an appropriate hardness.
It is a preferable embodiment that the immiscible penetration of the adhesive body 13 is about 35 and the hardness of the side elastic film 14a is about 50 in E hardness.

Next, the manufacturing method of the heat conductive sheet 11 is illustrated.
First, a heat conductive composition 17 is prepared by mixing a polymer base material (which may be a main agent and a curing agent that become a polymer base material after mixing) and a heat conductive filler with a stirrer. During mixing, it is preferable to stir and knead under vacuum in order to prevent mixing of air. And as shown in FIG. 3, the film sheet 2 is spread | laid on the conveyor 1 surface, the heat conductive composition 17 is apply | coated using this bar coater 3 on this film sheet 2, and the heat conductive composition 17 is made into a sheet form. To form a large sheet 18 that is larger than the size of the thermal conductive sheet 11 desired as a product. The large sheet 18 having a uniform thickness moves on the conveyor 1 in the direction indicated by the arrow, and is conveyed to the cutting process.
Next, as shown in FIG. 4, a cutting blade is inserted in the crossing direction (arrow direction) with respect to the surface of the large sheet 18 (first cutting step). Then, as shown in FIG. 5, the cutting blade 4 coated with the film forming agent 16 is re-entered into the recess 12 e formed by the primary cutting of the large sheet body 18 to attach the film forming agent 16 to the cut surface. (Second cutting process).

These cutting processes are performed both in the vertical direction and in the horizontal direction, and by reacting and curing the film forming agent, the cutting process is divided into desired sizes by a cutting line CL as shown in FIG. The heat conductor 12 having the non-adhesive side elastic film 14a formed on the side surface is obtained.
Finally, unnecessary portions are removed to obtain a plurality of heat conductors 12 arranged and placed on the film sheet 2 as shown in FIG. 7, and the individual heat conductors 12 having a desired size are heated. It can be used as the conductive sheet 11.

In the first cutting process and the second cutting process, the primary process is a main cutting process in which the large sheet 18 is completely cut. In the second cutting process, a film is formed on the cut surface without cutting. It can be set as the process of attaching an agent. Since substantial cutting is not performed in the second cutting step, it can be replaced with a cutting blade having a shape suitable for application of the film forming agent. Therefore, it is easy to apply the film forming agent to a desired application thickness in the second cutting step.
In addition, the primary cutting process is a temporary cutting process in which the large sheet body 18 is cut without being completely cut, and the second cutting process is a main cutting to completely cut the large sheet body and a film on the cut surface. It can be set as the process of attaching a forming agent. Since the main cutting process is performed after the provisional cutting process, the heat conductor 12 having a cut surface can be obtained, whereby the heat conductor 12 having a well-formed shape can be obtained. And since these processes have a two-step insertion process, it is preferable because the film forming agent is less likely to adhere to the front surface or the back surface intersecting the side surface.

If the cutting blades used in the first cutting process and the second cutting process are the same cutting blade, the shape of the cutting blade in the second cutting process matches the cutting surface cut in the first cutting process. For this reason, the film forming agent can be adhered to the cut surface. On the other hand, if another cutting blade is used, a cutting blade suitable for cutting the large sheet 18 is adopted in the first cutting step, and a cutting blade suitable for coating the film forming agent is used in the second cutting step. The cutting blade can be divided for each function. For example, the cutting blade used in the first cutting step can be made of a V-shaped metal, and the cutting blade used in the second cutting step can be made of flat plastic. Therefore, a plastic plate or the like can be appropriately used as the cutting blade, regardless of its name, in addition to a cutting tool such as a press cutting blade or a shearing blade.
Further, since the adhesive body 13 that enters the blade in the first cutting process has adhesiveness, the cutting blade and the large sheet body 18 are cooled to perform the first cutting process so that the adhesive body 13 does not easily stick to the cutting blade. It is preferable.

  If the primary cutting process and the secondary cutting process are sequentially performed from the end of the large sheet body 18 while the large sheet body 18 is moved, the primary cutting process and the second cutting process are performed in a flow operation. Since both cutting processes can be performed, it is preferable from the viewpoint of shortening the working time. When the primary cutting process is performed by cooling the cutting blade or the large sheet body 18, the first cutting process for the entire large sheet body 18 is completed and then the process proceeds to the second cutting process. You may make it do.

In this embodiment, although the cutting process is made into two processes, a 1st cutting process and a 2nd cutting process, both processes can also be performed in one process. In this case, a film forming agent is applied to the cutting blade, and the cutting of the large sheet body 18 and the application of the film forming agent to the cut surface are performed simultaneously. By reducing the number of times of cutting, the lead time can be shortened and the manufacturing cost can be reduced.
In addition, the large sheet 18 can be formed by a doctor blade method, a calendar molding method, an extrusion method using a T die, or the like instead of the method using a bar coater.

  Even when the film forming agent that becomes the side elastic film 14a includes a curing agent that reacts with the main agent contained in the adhesive body 13 and cures, a heating process that accelerates the curing reaction of the curing agent is appropriately performed. It is preferable to cure the film forming agent together with the pressure-sensitive adhesive body 13 after forming the film 18 and applying the film forming agent. This is because if only the adhesive body 13 is heated before application of the film forming agent, the base and the curing agent in the adhesive body 13 cause a curing reaction, and the curing reaction with the curing agent in the film forming agent hardly occurs.

According to the heat conductive sheet 11, even if the side surfaces of the plurality of heat conductors 12 arranged on the film sheet 2 come into contact with each other during the packing or transport process, they are difficult to stick and easy to remove. Therefore, the handleability when the thermally conductive sheet 11 is mounted on a heating element or the like is improved.
Further, even if the adhesive body 13 is made of a viscous and non-elastic material, elasticity can be imparted to the side elastic coating 14a, and the shape of the heat conductive sheet 11 is maintained by covering the side with the side elastic coating 14a. can do.

Second Embodiment [FIGS. 8 to 10] :
The heat conductive sheet 21 of this embodiment and its manufacturing method are shown in FIGS. FIG. 8 is a cross-sectional view of the heat conductive sheet 21, and FIGS. 9 and 10 are explanatory views showing a method for manufacturing the heat conductive sheet 21.
Unlike the heat conductive sheet 11 of the previous embodiment, the heat conductive sheet 21 of the present embodiment is provided with an elastic film 14b on the surface to be in close contact with either the heating element or the heat radiating body.

Specifically, the heat conductor 22 forming the heat conductive sheet 21 has the adhesive body 13 and the non-adhesive side elastic film 14a formed on the four side surfaces along the thickness direction, and the thickness. A back elastic film 14b is also formed on one surface crossing the direction (hereinafter referred to as “back surface” in the vertical direction of the drawing for convenience of explanation). The back elastic film 14b is a part that is harder than the adhesive body 13 and has a repulsive force (elasticity), like the side elastic film 14a formed on the side surface.
The back elastic film 14b may be made of the same material as the side elastic film 14a formed on the side surface, but may be made of a different material.

The example of manufacture of the heat conductive sheet 21 is shown next. First, in the present embodiment, a polymer base material (which may be a main agent and a curing agent that becomes a polymer base material after mixing) and a heat conductive filler are mixed with a stirrer to form an adhesive body 23. A thermally conductive composition 27a is prepared. On the other hand, a hard heat conductive composition 27b in which the addition amount of the curing agent is larger than that of the soft heat conductive composition 27a is prepared on the same polymer substrate as the soft heat conductive composition 27a. This hard heat conductive composition 27b is used to form the back elastic film 14b formed on the back surface.
Next, the heat conductive composition 27b for hard is apply | coated to the film sheet 2 mounted in the conveyor 1 (refer FIG. 9), and a hardening | curing agent is apply | coated on it (not shown). Further, when a soft heat conductive composition 27a is further applied thereon (see FIG. 10), a large sheet 28 in which the hard heat conductive composition 27b and the soft heat conductive composition 27a are laminated is obtained. . The large sheet 28 is moved in the direction indicated by the arrow on the conveyor 1 and conveyed to the cutting process.
Thereafter, a cutting step is performed in the same manner as the method described in the previous embodiment to obtain a heat conductor 22 having a desired size with a film forming agent attached to the side surface. Finally, the film forming agent is cured to obtain the heat conductive sheet 21.

  Even in this embodiment, it is preferable to cure the film forming agent together with the adhesive body 13 after molding the large sheet 28 and after applying the film forming agent to the side surfaces, but this is due to the softness of the hard thermal conductive composition 27b. For example, when it is difficult to form the large sheet 28 itself, it is possible to incorporate an appropriate heating step so that the back elastic film 14b has an appropriate hardness.

The back elastic film 14b to be formed on the back surface is obtained by applying and forming an adhesive that cures by itself or a curing agent that does not contain the main agent on the film sheet 2 instead of applying the hard heat conductive composition 27b. Can do. Moreover, the application | coating can also be abbreviate | omitted for the hardening | curing agent apply | coated after application | coating of the heat conductive composition 27b for hard, and before application | coating of the heat conductive composition 27a for soft.
The back elastic film 14b and the adhesive body 13 can be formed by the above-described methods other than the method using a bar coater. However, the material for the back elastic film 14b (the hard thermal conductive composition 27b) and the adhesive body 13 are used. Two-color molding in which the material (thermally conductive composition for soft 27a) is extruded at the same time is preferable in terms of increasing production efficiency and dimensional accuracy.

  Since the heat conductive sheet 21 is provided with the back surface elastic film 14b on the back surface of the heat conductor 22 (the surface on either side to be in close contact with the heat generator or the heat radiator), the tearing force in the width direction of the heat conductive sheet 21 As a result, resistance is increased and regularity can be further improved. Moreover, since the adhesiveness with respect to the film sheet 2 weakens, it becomes easy to peel off from the film sheet 2, and the workability | operativity in the mounting operation to a heat generating body or a heat radiator improves.

  Further, when the side elastic film 14a formed on the side surface and the back elastic film 14b formed on the back surface are both formed using the same film forming agent, the elastic film 14a and 14b are integrated with each other to be clear. Since the interface does not appear, both the elastic coatings 14a and 14b are difficult to peel off, and the fixed form maintainability is further improved.

Third Embodiment [FIGS. 11 and 12] :
The heat conductive sheet 31 of this embodiment and its manufacturing method are shown in FIGS. FIG. 11 is a cross-sectional view of the heat conductive sheet 31, and FIG. 12 is an explanatory view showing a method for manufacturing the heat conductive sheet 31.
The heat conductive sheet 31 of this embodiment is provided with elastic films 14b and 14c on both the front and back surfaces to be in close contact with the heating element and the heat dissipation element.

  Specifically, the heat conductor 32 forming the heat conductive sheet 31 has a non-adhesive side elastic film 14a formed on the adhesive body 13 and four side surfaces along the thickness direction, and has a thickness. A back elastic film 14b is provided on the surface on one side crossing the direction (for the sake of convenience, referred to as the “back surface” in the vertical direction of the drawing), and the surface on the other side (for convenience, referred to as the “surface” in the vertical direction of the drawing). A surface elastic film 14c is formed. These elastic films 14b and 14c are also harder than the adhesive body 13 and have a repulsive force (elasticity) like the side elastic film 14a formed on the side surface. Therefore, these elastic films 14b and 14c may be made of the same material as the side elastic film 14a formed on the side surfaces, but may be made of different materials. Furthermore, each elastic film 14a, 14b, 14c may have the same hardness or different hardness.

The heat conductive sheet 31 is manufactured in the same manner as in the previous embodiment by laminating the heat conductive composition for the back elastic film 14b and the heat conductive composition for the adhesive body 13 on the film sheet 2. (See FIG. 10), and a laminated body is formed. Separately from this, a heat conductive composition to be the surface elastic film 14c is prepared and formed into a sheet shape to prepare the surface elastic film 14c. A curing agent is applied to the surface elastic film 14c (not shown), and the coated surface is placed on the previous laminate and laminated (FIG. 12). Then, the side elastic film 14a is formed on the side surface in the same manner as in the previous embodiment.
Alternatively, the heat conductive compositions that respectively become the back elastic film 14b, the adhesive body 13, and the surface elastic film 14c are formed, and each heat conductive composition can be injection-molded so that the respective portions are laminated. .
When both front and back elastic coatings 14b and 14c formed in the form of a sheet are used, and a hardener is applied to the surface and fixed to the adhesive body 13, the adhesive body is compared with the case where each member is simultaneously injected and fixed. 13 and the elastic coatings 14b, 14c can be changed in thickness, and the properties of the heat conductive sheet 31 obtained can be changed by changing the manufacturing method.

  Since the heat conductive sheet 31 is provided with the elastic coatings 14b and 14c on both the front and back surfaces of the heat conductor 32 (both the surface to be in close contact with the heat generating body and the surface to be in close contact with the heat dissipating body), The resistance further increases with respect to the tearing force to be directed, and the formability can be further enhanced as compared with the heat conductive sheet 21. Moreover, since the adhesiveness with respect to the finger | toe and the handling tool which hold | grip the heat conductive sheet 31 becomes weak at the time of mounting to a heat generating body or a heat radiating body, handling property improves and workability | operativity in mounting work improves.

Further, since the side surfaces and both front and back surfaces of the heat conductor 32 are covered with the elastic coatings 14a, 14b, and 14c, the formability is improved and mounting errors during mounting work can be reduced. Therefore, it is possible to reduce excess inventory (stored amount). Even if the adhesive body 13 is formed of a material that exhibits almost only viscous deformation, it can be shaped by enclosing it with elastic films 14a, 14b, 14c.
Furthermore, by changing the hardness of the front surface and the back surface, the hardness can be appropriately corrected in accordance with the characteristics of the heat generating body and the heat dissipating body such as the size, the contact area, and the pressing load.

  In the present embodiment, the thickness of the back elastic film 14b on the one surface side is about 0.2 mm, the hardness is about 50 in E hardness, and the thickness of the surface elastic film 14c on the other surface side is about 0.2 mm. It is a preferred embodiment that the hardness is about 70 in terms of E hardness and the immiscibility of the viscous body 13 is about 35.

Modification [FIG. 13] :
The side elastic film 14a formed on the side surfaces of the heat conductive sheets 11, 21, 31 can be formed on a part of the side surface without being formed on the entire surface (all) of the side surface. For example, in the heat conductive sheet 41 shown in FIG. 13A, a side elastic film 14a is formed on one of two opposing side surfaces. Moreover, in the heat conductive sheet 51 shown in FIG.13 (B), the side surface elastic film 14a is formed except the central vicinity of each side surface. Further, in the heat conductive sheet 61 shown in FIG. 13C, the side elastic film 14a is formed only in the vicinity of the center in the pair of opposing side surfaces, and the side elastic film 14a is formed in the other side surface except for the vicinity of the center. Is forming. Such heat conductive sheets 41, 51, 61 can be manufactured by adjusting the position of the film forming agent 14 to be attached to the cutting blade. In the heat conductive sheets 41, 51, 61, since the side surface portion on which the side surface elastic film 14 a is not formed easily swells outwardly when compressed, it is more easily crushed than when the side surface elastic film 14 a is formed on the entire side surface. The compression load can be reduced.

Experimental example :
A sample having a side elastic film (14a) on the side and a sample not having the side elastic film were prepared and subjected to a compression test using a load measuring device.
The sample has a thickness of 2.4 mm and a width of 10 mm square, and a heat conductive sheet (11) having a side elastic film 14a on all four side surfaces is a sample 1, and a side elastic film (14a) is formed on any of the four side surfaces. Sample 2 was not formed. In both Sample 1 and Sample 2, the hardness of the portion of the adhesive body (13) is E hardness 0 (immiscible consistency 35).
For comparison, Sample 3 was prepared in which the side elastic film (14a) was not formed on any of the four side surfaces, and the hardness of the adhesive body (13) was E hardness 10.
In the compression test, a sample having a thickness of 2.4 mm was gradually compressed, and a load value at a predetermined compression rate was measured. The results are shown in Table 1.

  The sample 1 with the side elastic coating (14a) has a slightly larger load than the sample 2 without the side elastic coating (14a) at any compression rate, whether the compression rate is large or small. It can be seen that the presence of the side elastic coating (14a) has a resistance (repulsive force) in the thickness direction of the sheet. Further, it can be seen that the load of sample 1 is lower than that of sample 3 having an E hardness of 10, even though the side elastic coating (14a) is formed.

DESCRIPTION OF SYMBOLS 1 Conveyor 2 Film sheet 3 Bar coater 4 Cutting blade 5 Roller 11 Thermally conductive sheet (1st Embodiment)
12 Thermal Conductor 12e Dimple 13 Adhesive Body 14 Elastic Film 14a Side Elastic Film 14b Back Elastic Film 14c Surface Elastic Film 16 Film Forming Agent 17 Thermal Conductive Composition 18 Large Format Sheet 21 Thermal Conductive Sheet (Second Embodiment)
22 Thermal Conductor 27a Thermal Conductive Composition for Soft 27b Thermal Conductive Composition for Hard 28 Large Format Sheet 31 Thermal Conductive Sheet (Third Embodiment)
32 Thermal Conductor 38 Large Format Sheet 41 Thermal Conductive Sheet (First Modification)
42 Thermal Conductor 51 Thermal Conductive Sheet (Second Modification)
52 Thermal Conductor 61 Thermal Conductive Sheet (Third Modification)
62 Thermal conductor CL Cut line

Claims (7)

In the method for producing a thermally conductive sheet in which a thermally conductive filler is dispersed in a polymer substrate,
Forming a large sheet body obtained by molding a heat conductive composition in which a heat conductive filler is blended into a polymer base material into a sheet having a size larger than a desired size;
A step of cutting a cutting blade coated with a film forming agent in a crossing direction with respect to the surface of the large sheet body, cutting the large sheet body and attaching the film forming agent to the cut surface;
Curing the film forming agent attached to the cut surface to form a non-adhesive elastic film on the cut surface;
Is performed, and a heat conductive sheet having a non-adhesive elastic film on a side surface along the thickness direction is formed.   In the process of attaching the film forming agent, the first cutting process in which a cutting blade not coated with the film forming agent is inserted into the large sheet body, and the cutting blade coated with the film forming agent is inserted in the same place and cut. The manufacturing method of the heat conductive sheet of Claim 1 including the 2nd cutting process to which a film formation agent is made to adhere to.   A heat conductive sheet in which a heat conductive filler is dispersed in a polymer base material, and having a non-adhesive elastic film on a side surface along a thickness direction.   The heat conductive sheet according to claim 3, wherein the elastic film is a reaction film of a curing agent contained in a film forming agent attached to a side surface along the thickness direction and a base forming the polymer substrate.   The thermally conductive sheet according to claim 3 or 4, wherein the elastic film has a repulsive force against compression in the thickness direction.   The heat conductive sheet according to any one of claims 3 to 5, further comprising a non-adhesive elastic film on at least one of a front surface and a back surface intersecting the thickness direction.   The heat conductive sheet according to claim 6, wherein any one of the elastic films has a hardness different from that of the other elastic films.

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