JP2012160503A - Composite film, device and method for producing composite film - Google Patents

Abstract

PROBLEM TO BE SOLVED: To solve such a problem that there is a case where conventional heat conduction films cannot sufficiently suppress generation of heat spots.SOLUTION: A composite film 100 comprises: a first heat conduction layer 110 having heat conductivity in the surface direction higher than that in the thickness direction; and a first adhesion layer 120 laminated on one surface side of the first heat conduction layer 110 and having an opening penetrating through the first adhesion layer in the thickness direction. In the composite film 100, for example, an opening 122 is arranged on a location facing a heat source via the first heat conduction layer 110, so that heat spots generated in a member facing the heat source can be suppressed.

Description

  The present invention relates to a composite film, a device, and a method for producing the composite film.

When a heat source such as a battery or a semiconductor element mounted on the electronic device generates heat, a heat spot in which the temperature of a specific part of the electronic device is higher than the ambient temperature may occur. In order to suppress such a heat spot, a thermal conductive film having a thermal conductivity in the plane direction higher than that in the thickness direction is used (for example, see Patent Documents 1 to 3).
Patent Document 1 Japanese Patent Laid-Open No. 2009-94196 Patent Document 2 Japanese Patent No. 3810734 Patent Document 3 Japanese Patent No. 4498419

  However, the conventional heat conductive film as described above may not sufficiently suppress the heat spot.

  In order to solve the above problems, a composite film according to one embodiment of the present invention includes a first thermal conductive layer having a thermal conductivity in a plane direction higher than a thermal conductivity in a thickness direction, and one side of the first thermal conductive layer. And a first buffer layer having an opening.

  The composite film may be a heat spot suppressing film that suppresses a heat spot generated in a member facing the heat source by disposing an opening at a position facing the heat source via the first heat conductive layer.

  The composite film may be hermetically sealed by attaching a first buffer layer to a surface on the heat source side of a member facing the heat source.

  In the composite film, the first buffer layer may be an adhesive layer that bonds the member facing the heat source and the first heat conductive layer.

  In the composite film, the first buffer layer may include a protective layer that protects the surface of the first heat conductive layer on the first buffer layer side, and an adhesive layer that bonds the member facing the heat source and the protective layer. Good.

  In the composite film, an opening may be provided in the adhesive layer.

  In the composite film, the adhesive layer may be a double-sided adhesive film.

  In the composite film, an opening may be provided in the protective layer.

  In the composite film, the opening may penetrate the layer in which the opening is provided in the thickness direction.

  In the composite film, the first buffer layer may have a plurality of openings arranged.

  The composite film may further include a protective layer that protects the surface of the first heat conductive layer opposite to the surface on the first buffer layer side.

  The composite film is laminated on the surface side of the first buffer layer opposite to the surface on the first heat conductive layer side, and the second heat conductivity is higher in the surface direction than in the thickness direction. The layer may be further provided with a second buffer layer that is laminated on the surface of the second heat conductive layer opposite to the surface on the first buffer layer side and that has an opening.

  In the composite film, the opening area of the first buffer layer may be different from the opening area of the second buffer layer.

  In the composite film, the opening area of the first buffer layer may be smaller than the opening area of the second buffer layer.

  In the composite film, the first buffer layer and the second buffer layer have a plurality of openings, and the total area of the plurality of openings of the first buffer layer is greater than the total area of the plurality of openings of the second buffer layer. It may be small.

  In the composite film, the first heat conductive layer may be a graphite film produced by heat-treating a polymer film.

  A device according to one embodiment of the present invention includes a heat source, a housing that houses the heat source, and the composite film that is disposed between the heat source and the inner wall of the housing, and the first buffer layer includes the first heat layer. It is provided on the inner wall side of the housing from the conductive layer, and the opening is arranged at a position facing the heat source.

  In the above device, the composite film may be attached to the inner wall of the housing.

  The manufacturing method of the composite film which concerns on 1 aspect of this invention is the process of forming an opening in a double-sided adhesive film, and the double-sided adhesive film in which opening was formed. And a step of attaching to a high heat conductive film.

  The composite film according to one embodiment of the present invention has an opening penetrating in the thickness direction, and is laminated on one surface of the heat conduction layer, with a heat conductivity in the surface direction higher than the heat conductivity in the thickness direction. The first buffer layer and the second buffer layer stacked on the other surface of the heat conductive layer are provided, and the opening is sealed by the first buffer layer and the second buffer layer.

  The composite film may be a heat spot suppressing film that suppresses a heat spot generated in a member facing the heat source by arranging an opening at a position facing the heat source.

  In the composite film, the first buffer layer may include an adhesive layer that bonds the member facing the heat source and the heat conductive layer.

  In the composite film, the second buffer layer may include a protective layer that protects the heat conductive layer.

  In the composite film, the heat conductive layer may be a graphite film produced by heat-treating a polymer film.

  A device according to one embodiment of the present invention includes a heat source, a housing that houses the heat source, and the composite film that is disposed between the heat source and the inner wall of the housing, and the opening is located at a position facing the heat source. Is arranged.

  In the above device, the composite film may be attached to the inner wall of the housing.

  A device according to an aspect of the present invention includes a step of forming an opening penetrating in a thickness direction in a heat conductive film having a thermal conductivity in a plane direction higher than a thermal conductivity in a thickness direction, and a heat conductive film in which the opening is formed A step of attaching a first film that covers one side of the opening to one side of the opening, and a second film that closes the other side of the opening to the other surface of the heat conductive film in which the opening is formed. Attaching.

  It should be noted that the above summary of the invention does not enumerate all the necessary features of the present invention. In addition, a sub-combination of these feature groups can also be an invention.

It is a top view of a composite film. It is a figure which shows sectional drawing of a composite film. It is a figure for demonstrating the manufacturing method of a composite film. It is a figure for demonstrating the manufacturing method of a composite film. It is a figure for demonstrating the manufacturing method of a composite film. It is a figure for demonstrating the manufacturing method of a composite film. It is a figure which shows sectional drawing of the device with which the composite film was affixed. It is a figure which shows sectional drawing of a composite film. It is a figure which shows sectional drawing of a composite film. It is a top view of a composite film. It is a figure which shows sectional drawing of a composite film. It is a figure which shows sectional drawing of a composite film. It is a figure which shows sectional drawing of a composite film. It is a figure which shows sectional drawing of a composite film. It is a figure which shows sectional drawing of a composite film. It is a figure for demonstrating the manufacturing method of a composite film. It is a figure for demonstrating the manufacturing method of a composite film. It is a figure for demonstrating the manufacturing method of a composite film. It is a figure for demonstrating the manufacturing method of a composite film. It is a figure for demonstrating the manufacturing method of a composite film. It is sectional drawing which shows the structure containing the sample used for evaluation.

  Hereinafter, the present invention will be described through embodiments of the invention, but the following embodiments do not limit the invention according to the claims. In addition, not all the combinations of features described in the embodiments are essential for the solving means of the invention.

  The composite film according to the present embodiment includes a heat conductive layer and a buffer layer. The heat conductive layer is a material having anisotropy in which the thermal conductivity in the plane direction is higher than the thermal conductivity in the thickness direction. The buffer layer is a layer laminated on the heat conductive layer. The buffer layer is composed of, for example, an adhesive layer, a protective layer, an insulating layer, an adhesive layer, etc., and may be composed of a single layer, or may be composed of two or more layers, and may be composed of the same or different layers. .

  FIG. 1A shows a plan view of a composite film 100 according to this embodiment. FIG. 1B shows a cross-sectional view of the composite film 100 taken along line AA shown in FIG. 1A.

  The composite film 100 is affixed to an inner wall, which is the back surface of the outer wall with which a human body of a housing that houses a heat source such as a battery or a semiconductor element comes into contact. Thereby, the heat spot which generate | occur | produces on the outer wall etc. of the housing | casing facing a heat source is suppressed.

  The composite film 100 includes a first heat conductive layer 110 and a first adhesive layer 120. The first adhesive layer 120 is an example of a first buffer layer. The first adhesive layer 120 is laminated on one surface 110 a of the first heat conductive layer 110 and has an opening 122. In the present embodiment, an example in which the opening 122 penetrates in the thickness direction in the first adhesive layer 120 will be described. In other embodiments, the opening 122 may not penetrate in the thickness direction. The opening 122 may be a concave opening formed on any surface of the first adhesive layer 120, for example.

  As described above, the first heat conductive layer 110 is a material having anisotropy in which the thermal conductivity in the plane direction is higher than the thermal conductivity in the thickness direction. As the 1st heat conductive layer 110, the graphite film produced | generated by heat-processing a polymer film can be used, for example. The thermal conductivity in the plane direction of such a graphite film is preferably 750 W / m · K or more, more preferably 900 W / m · K or more, and further preferably 1100 W / m · K or more. Further, the thermal conductivity in the thickness direction of such a graphite film may be 10 W / m · K or less. Further, as the first heat conductive layer 110, a graphite film produced by acid treatment and heat treatment of graphite powder that has been crystallized, such as natural graphite, can be used. The thermal conductivity in the plane direction of such a graphite film is preferably 200 W / m · K or more, more preferably 300 W / m · K or more, and further preferably 400 W / m · K or more. Further, the thermal conductivity of the thickness of such a graphite film may be 10 W / m · K or less. In addition, the thickness of the 1st heat conductive layer 110 becomes like this. Preferably it is 10 micrometers or more, More preferably, it is 20 micrometers or more, More preferably, it is 30 micrometers or more.

  The first adhesive layer 120 adheres the composite film 100 to a specific part such as the inner wall of the housing. The thickness of the 1st contact bonding layer 120 becomes like this. Preferably it is 10 micrometers or more, More preferably, it is 20 micrometers or more, More preferably, it is 30 micrometers or more.

  As the 1st contact bonding layer 120, a double-sided adhesive film, an adhesive agent, or an adhesive can be used, for example. As the double-sided adhesive film, for example, a resin film coated with an adhesive can be used. As an adhesive, for example, an epoxy resin, a phenol resin, a polyimide resin, or the like can be used. Moreover, as an adhesive, resin, such as an acrylic type and a silicone type, can be used, for example.

  2A to 2D show a method for manufacturing the composite film 100. 2A to 2D show a method of manufacturing the composite film 100 when a double-sided pressure-sensitive adhesive film is used as the first adhesive layer 120.

  A double-sided pressure-sensitive adhesive film A as an example of the first adhesive layer 120 is prepared (FIG. 2A). Next, an opening 122 penetrating in the thickness direction is formed using a cutter or the like in a specific portion of the double-sided pressure-sensitive adhesive film A, for example, a portion other than the peripheral portion such as the central portion (FIG. 2B). Moreover, the graphite film G which is an example of the 1st heat conductive layer 110 is prepared (FIG. 2C). Next, the double-sided pressure-sensitive adhesive film A and the graphite film G are attached to produce a composite film 100 (FIG. 2D). As described above, a composite film can be produced simply by attaching a double-sided pressure-sensitive adhesive film having an opening to a graphite film. Therefore, an increase in manufacturing cost can be suppressed.

  When an adhesive or a pressure sensitive adhesive is used as the first adhesive layer 120, a mask layer is formed in advance in a region corresponding to the opening 122 of the surface 110a of the first heat conductive layer 110. Furthermore, after applying an adhesive or an adhesive to the surface 110a on which the mask layer is formed, the composite film 100 can be manufactured by removing the mask layer.

  Here, when using the graphite film produced | generated by heat-processing a polymer film as the 1st heat conductive layer 110, the graphite film produced by the manufacturing method shown below can be used.

  Polymer films suitable for the production of graphite films include polyimide, polyamide, polyoxadiazole, polybenzothiazole, polybenzobisazole, polybenzoxazole, polybenzobisoxazole, polyparaphenylene vinylene, polybenzimidazole, polybenzo Examples thereof include at least one polymer film selected from bisimidazole and polythiazole.

  In particular, a polyimide film is preferable as the polymer film. This is because a polyimide layer structure is easily developed by carbonization and graphitization in a polyimide film as compared with a polymer film using other organic materials as a raw material.

  There is no restriction | limiting in particular about the birefringence of a polyimide film. However, if the birefringence is 0.08 or more, carbonization and graphitization of the film easily proceeds, so that a graphite film having a developed graphite layer is easily obtained. Birefringence means a difference between a refractive index in an arbitrary direction in the film plane and a refractive index in the thickness direction.

  In order to obtain a graphite film from the polymer film, the carbonization step and the graphitization step may be performed continuously or discontinuously. In the carbonization step, the polymer film as a starting material is carbonized by preheating treatment under reduced pressure or in an inert gas. This carbonization is usually performed at a temperature of about 1000 ° C. For example, when the preheating treatment is performed at a rate of temperature increase of 10 ° C./min, it is desirable to keep the temperature in the temperature range of 1000 ° C. for about 30 minutes. In the preheating treatment stage, pressure in the surface direction may be applied so that the orientation of the polymer film is not lost. The graphitization step subsequent to the carbonization step is performed by setting a carbonized carbonized film in an ultrahigh temperature furnace. The graphitization step is performed under reduced pressure or in an inert gas. Argon is most suitable as the inert gas, and it is more preferable to add a small amount of helium to the argon. The heat treatment temperature for graphitization is at least 2400 ° C. or more, more preferably 2600 ° C. or more, further preferably 2800 ° C. or more, and particularly preferably 2900 ° C. or more.

  In order to create an ultra-high temperature of 2500 ° C. or higher, for example, a method can be mentioned in which an electric current is directly applied to a graphite heater and the Joule heat is used for heating. Graphitization is performed by softening the carbonized film prepared in the pretreatment to a graphite structure. The molecular orientation of the polymer film affects the carbon alignment of the carbonized film. As a result, the carbon-carbon bond cleavage / recombination energy in the graphitization process is reduced. Therefore, the molecular design is performed so that the molecules are oriented, and by realizing a high degree of orientation, graphitization at a low temperature and softening to a high-quality graphite film are possible.

  FIG. 3 shows a cross-sectional view of the device 200 with the composite film 100 attached to the inner wall. The device 200 includes a housing 10, a substrate 20, and an electronic component 22 mounted on the substrate 20. The composite film 100 has an opening 122 positioned at a position facing the electronic component 22 serving as a heat source, and is attached to the inner wall 10 a of the housing 10 via the first adhesive layer 120.

  With this configuration, the heat generated from the electronic component 22 and transmitted to the composite film 100 is transmitted and diffused in the surface direction of the first heat conductive layer 110. The opening 122 forms a sealed space by the first heat conductive layer 110 and the inner wall 10a, and the sealed space functions as a heat insulating layer. Therefore, the heat transmitted in the thickness direction of the first heat conductive layer 110 is not easily transmitted to the region of the outer wall 10 b of the housing 10 that faces the opening 122. Therefore, according to the present embodiment, heat is diffused in the surface direction by the first heat conductive layer 110. Further, the opening 122 of the first adhesive layer 120 functions as a heat insulating layer. Therefore, the heat spot which generate | occur | produces in the outer wall 10b of the housing | casing 10 when the electronic component 22 generates heat | fever can be suppressed.

  Here, the position facing the heat source includes not only a position where at least a part of the heat source overlaps in the thickness direction but also a position which does not overlap the heat source in the thickness direction. Further, the position facing the heat source may be a position facing any surface of the electronic component 22 serving as the heat source. For example, the position facing the heat source may be a bonding surface of the electronic component 22 to the substrate 20, an upper surface that is a surface opposite to the bonding surface, or a position facing the bonding surface and a side surface other than the upper surface.

  FIG. 3 shows an example in which the electronic component 22 and the opening 122 are arranged in the overlapping direction in the thickness direction of the composite film 100. However, the position where the opening 122 is disposed may be a position corresponding to a position where a heat spot can be generated. Therefore, when the position where the heat spot is generated is a position where the electronic component 22 does not overlap in the thickness direction, the electronic component 22 and the opening 122 may be disposed where they do not overlap in the thickness direction. For example, when another member is disposed between the electronic component 22 and the housing 10 or when the thickness of the housing 10 is not uniform, a heat spot is generated at a position overlapping the heat source in the thickness direction. Not exclusively. In this case, the opening 122 may be disposed at a position that does not overlap the heat source in the thickness direction.

  FIG. 4 is a cross-sectional view of a composite film 100 </ b> A that is a modification of the composite film 100. The composite film 100 </ b> A includes a protective layer 130 that protects the surface 110 b on the heat source side of the first heat conductive layer 110 in addition to the first heat conductive layer 110 and the first adhesive layer 120. The protective layer 130 is disposed on the surface 110b side of the first heat conductive layer 110. Therefore, by positioning the composite film 100A with the opening 122 positioned at a position facing the heat source, it is possible to suppress a heat spot generated on a member disposed on the surface 100a side opposite to the heat source of the composite film 100A. Furthermore, by providing the protective layer 130, for example, a part of the graphite film constituting the first heat conductive layer 110 is peeled off, and a problem caused by the peeled part adhering to another member can be prevented.

  As the protective layer 130, a resin tape in which an adhesive or adhesive such as acrylic, silicone, epoxy, or polyimide is applied to one surface of a resin film such as polyimide, polyethylene terephthalate, polyethylene, polypropylene, or polyester. Can be used. Further, as the protective layer 130, a hot melt type (thermoplastic) tape such as polyester can be used. Furthermore, the protective layer 130 may be laminated on the surface 110b of the first heat conductive layer 110 by coating using an epoxy, phenol or rubber-based paint.

  FIG. 5 shows a cross-sectional view of a composite film 100 </ b> B that is a modification of the composite film 100. The composite film 100 </ b> B includes a protective layer 140 that protects the surface 110 a opposite to the heat source of the first heat conductive layer 110. The protective layer 140 is an example of a first buffer layer, and has an opening 142 that is stacked on the surface 110a of the first heat conductive layer 110 and penetrates in the thickness direction. The same material as the protective layer 130 can be used for the protective layer 140. The adhesive layer 120 ′ does not have an opening penetrating in the thickness direction, and is laminated on one surface 140 a of the second protective layer 140. Therefore, the opening 142 is sealed by the first heat conductive layer 110 and the first adhesive layer 120 ′, and a sealed space is formed. That is, the opening 142 functions as a heat insulating layer. Therefore, by positioning the composite film 100B with the opening 142 positioned at a position facing the heat source, it is possible to suppress heat spots generated on the member on the opposite side to the heat source of the composite film 100B. Note that the adhesive layer 120 ′ may have an opening penetrating in the thickness direction at a position corresponding to the opening 142. In this case, the protective layer 140 and the adhesive layer 120 ′ are examples of the first buffer layer. Further, the protective layer 130 may be laminated on the other surface 110b of the first heat conductive layer 110 in the same manner as the composite film 100A.

  As described above, in the above embodiment, the example in which the first adhesive layer 120 or the protective layer 130 has a single opening has been described. However, the first adhesive layer 120 or the protective layer 130 may have a plurality of openings arranged. Also, the shape of the opening is not rectangular but may be other shapes such as a circle.

  FIG. 6A shows a plan view of a composite film 100 </ b> C that is a modification of the composite film 100. FIG. 6B shows a cross section of the composite film 100C taken along line AA shown in FIG. 6A. The composite film 100C includes a first adhesive layer 120 having a plurality of openings 122 arranged in a lattice pattern.

  Here, the area of each of the plurality of openings 122 may be sufficiently smaller than the entire area of the first adhesive layer 120. More specifically, the area of each of the plurality of openings 122 is preferably 20% or less, more preferably 10% or less, and even more preferably 5% or less of the entire area of the first adhesive layer 120.

The area of the opening is preferably 5 mm ² or more, more preferably 10 mm ² or more, and further preferably 20 mm ² or more.

  Thus, by arranging the plurality of openings 122 having a relatively small area in a lattice shape, the sealed space formed by the openings 122 is less likely to be crushed. Therefore, each of the plurality of openings 122 can function as a heat insulating layer more reliably.

  When forming a plurality of openings 122 arranged in the first adhesive layer 120, an adhesive or a pressure-sensitive adhesive is applied to the surface 110a opposite to the heat source of the first heat conductive layer 110 in a mesh shape. Also good. Thereby, the 1st contact bonding layer 120 which has the some opening 122 arrange | positioned at mesh shape is formed, and the composite film 100C can be produced.

  Furthermore, in the above embodiment, an example in which the area of the opening 122 is larger than the area of the electronic component 22 has been described. However, the area of the opening 122 may be smaller than or the same as the area of the electronic component 22.

  In the above-described embodiment, the composite film 100 has been described as being attached to the inner wall 10a that is the back surface of the outer wall 10b with which the human body of the housing 10 comes into contact. However, the composite film 100 may be affixed to other electronic components or substrates mounted on the housing 10 besides the inner wall 10a. The composite film 100 may be in contact with each of the inner wall 10a and the electronic component 22.

  FIG. 7 shows a cross-sectional view of a composite film 100 </ b> D that is a modification of the composite film 100. The composite film 100D is configured by laminating a plurality of heat conductive layers and adhesive layers (buffer layers). The second heat conductive layer 150 has an anisotropy in which the thermal conductivity in the plane direction is higher than the thermal conductivity in the thickness direction. The second heat conductive layer 150 is stacked on one surface 120 a of the first adhesive layer 120. The second adhesive layer 160 has an opening 162 penetrating in the thickness direction, and is laminated on one surface 150 a of the second heat conductive layer 150. Thus, a heat spot can be suppressed more reliably by laminating a plurality of heat conductive layers and adhesive layers. In addition, the 1st heat conductive layer 110 and the 2nd heat conductive layer 150 may use the graphite film with the same thermal conductivity of a surface direction and the thickness direction, and these other graphite films from which these heat conductivities differ. May be used.

  In addition, when the composite film 100 is configured by laminating a plurality of heat conductive layers and buffer layers, the area of each opening may be different. More specifically, the area of the opening of the buffer layer closer to the heat source may be smaller than the area of the opening of the adhesive layer farther from the heat source. Further, in the case where the buffer layer has a plurality of openings, the total area of the plurality of openings close to the heat source may be smaller than the total area of the plurality of openings of the buffer layer farther from the heat source.

  FIG. 8 shows a cross-sectional view of a composite film 100E that is a modification of the composite film 100. FIG. The composite film 100E includes a first adhesive layer 120 having a single opening 122 and a second adhesive layer 160 having a single opening 162. The area of the opening 122 of the first adhesive layer 120 is smaller than the area of the opening 162 of the second adhesive layer 160.

  FIG. 9 shows a cross-sectional view of a composite film 100 </ b> F that is a modification of the composite film 100. The composite film 100 </ b> F includes a first adhesive layer 120 having a plurality of openings 122 and a second adhesive layer 160 having a plurality of openings 162. The total area of the plurality of openings 122 included in the first adhesive layer 120 is smaller than the total area of the plurality of openings 162 included in the second adhesive layer 160.

  By configuring as shown in FIG. 8 or FIG. 9, the entire area of the heat insulating layer constituted by the opening 122 of the first adhesive layer 120 is relatively small. Therefore, heat conduction from the first heat conductive layer 110 closer to the heat source to the second heat conductive layer 150 is facilitated. Therefore, it becomes easier to diffuse the heat in the surface direction via the plurality of heat conductive layers. On the other hand, the entire area of the opening of the second adhesive layer 160 farther from the heat source is relatively large. Therefore, it becomes difficult to transfer heat to a surface such as a housing to which the second adhesive layer 160 is attached. Therefore, by comprising in this way, the heat spot which generate | occur | produces on surfaces, such as a housing | casing, can be suppressed more reliably.

  FIG. 10 shows a cross-sectional view of a composite film 100G, which is a modification of the composite film 100. The composite film 100G includes a first heat conductive layer 110 that is an example of a heat conductive layer or a heat conductive film, an adhesive layer 120 ′ that is an example of a first buffer layer or a first film, and an example of a second buffer layer or a second film. And a protective layer 130. The first heat conductive layer 110 has an opening 112 penetrating in the thickness direction. The adhesive layer 120 ′ is laminated on the surface 110a of the first heat conductive layer 110 on the heat source side, and the protective layer 130 is laminated on the surface 110b on the side opposite to the heat source.

  In the composite film 100G, the opening 112 is sealed by the protective layer 130 and the adhesive layer 120 ′ to form a sealed space. That is, the opening 112 functions as a heat insulating layer. When the composite film 100G is disposed with the opening 112 positioned at a position facing the heat source, the heat generated from the heat source is transmitted to the protective layer 130. At least a part of the heat transferred to the protective layer 130 is transferred to the first heat conductive layer 110. Here, since the opening 112 functions as a heat insulating layer, more heat is conducted to the first heat conductive layer 110 in contact with the protective layer 130 than the heat insulating layer formed by the opening 112. Further, the heat transmitted to the first heat conductive layer 110 is transmitted and diffused in the surface direction. Accordingly, heat is not easily transmitted to the region of the adhesive layer 120 ′ corresponding to the opening 112. Therefore, by positioning the opening 112 at a position facing the heat source and disposing the composite film 100G, heat spots generated on the member disposed on the surface opposite to the heat source of the composite film 100G can be suppressed.

  11A to 11E show a method for manufacturing the composite film 100G. 11A to 11D show a method for manufacturing the composite film 100 when a double-sided pressure-sensitive adhesive film is used as the first adhesive layer 120 ′ and a PET tape is used as the protective layer 130.

  A graphite film G is prepared as the first heat conductive layer 110 (FIG. 11A). An opening 112 penetrating in the thickness direction is formed by using a cutter or the like in a specific portion of the graphite film G, for example, a portion other than the peripheral portion such as the central portion (FIG. 11B). A PET tape P is prepared, and one surface of the PET tape P and one surface of the graphite film G are bonded together to block one side of the opening 112 (FIG. 11C). Moreover, the double-sided adhesive film A is prepared, the one surface of the double-sided adhesive film A and the other surface of the graphite film G are bonded together, and the other side of the opening 112 is closed (FIG. 11D), thereby producing a composite film 100G ( FIG. 11E).

  As described above, the composite film 100G in which the opening 112 formed in the graphite film G is sealed with the PET tape P and the double-sided adhesive film A can be produced. Note that the PET tape P may be bonded to the graphite film G after the double-sided adhesive film A is bonded to the graphite film G in which the opening 112 is formed. Further, the double-sided adhesive film A and the PET tape P may be simultaneously bonded to the graphite film G in which the opening 112 is formed.

  The composite film may be directly attached to the heat source. In this case, it is preferable to arrange the first heat conductive layer on the heat source side from the first buffer layer. Further, the configuration of the first buffer layer may be the same as the configuration in the case where the composite film is attached to the member facing the heat source.

  Hereinafter, some examples according to the above-described embodiment will be described together with comparative examples.

<Evaluation method>
FIG. 12 is a cross-sectional view showing a configuration including the sample S used for the evaluation. In FIG. 12, a sample S including a graphite film G and an adhesive layer A having an opening O is shown as an example of a composite film to be evaluated. A heating element H is fixed to the center of the epoxy resin substrate E. The sample S is attached to a support B made of ABS (acrylonitrile butadiene styrene) resin with an opening O disposed at a position overlapping the heating element H in the thickness direction.

  The size of the heating element H is 10 mm × 10 mm, the thickness is 1 mm, and the power consumption is 1 W. The size of the epoxy resin substrate E is 50 mm × 50 mm and the thickness is 1 mm. The size of the sample S is 50 mm × 50 mm, and the size of the opening O is 10 mm × 10 mm. The support B has a size of 60 mm × 60 mm and a thickness of 1.5 mm.

  In the example shown in FIG. 12, the central part of the heating element H and the central part of the sample S are arranged at the same position in the thickness direction. That is, the heating element H and the opening O are arranged at positions that overlap in the thickness direction. In such a sample structure, the temperature (° C.) of the central portion of the heating element H after 600 seconds from the start of heat generation (when it reaches a steady state) and the central portion of the outer surface of the support B (this portion is the heating element H). The heat dissipation and heat insulation properties were evaluated by measuring the temperature (° C.) of (located directly above the central part of).

  The evaluation of the temperature at the center of the outer surface of the support B is “◎” when it is less than 40 ° C., “◯” when it is 40 ° C. to 45 ° C., “Δ” when it is 45 ° C. to 50 ° C., and higher than 50 ° C. The case was set as “x”.

  Evaluation of the temperature of the central part of the heating element H was “◎” when the temperature was lower than 45 ° C., “Δ” when the temperature was 45 ° C. to 50 ° C., and “X” when the temperature was higher than 50 ° C.

  As the graphite film G used in this evaluation, a film produced by the production method shown below is used.

  One equivalent of pyromellitic dianhydride was dissolved in a DMF (dimethylformamide) solution in which one equivalent of 4,4′-oxydianiline was dissolved to obtain a polyamic acid solution (18.5 wt%). While this dissolution was cooled, an imidization catalyst containing 1 equivalent of acetic anhydride, 1 equivalent of isoquinoline, and DMF was added to the carboxylic acid group contained in the polyamic acid to degas. Next, this mixed solution was applied onto an aluminum foil so as to have a predetermined thickness (75 μm) after drying. The mixed solution layer on the aluminum foil was dried using a hot air oven and a far infrared heater. As described above, a polyimide film having a thickness of 75 μm was produced.

  The polyimide film thus produced was sandwiched between graphite plates, and carbonized by raising the temperature to 1000 ° C. using an electric furnace. A carbonized film obtained by carbonization is sandwiched between graphite plates, and graphitized by heating to 2900 ° C. at a rate of temperature increase of 1 ° C./min using a graphitization furnace to obtain a graphite film G having a thickness of 40 μm. Obtained.

  The double-sided pressure-sensitive adhesive film A used as an adhesive layer in this evaluation was a double-sided pressure-sensitive adhesive tape having a thickness of 10 μm (acrylic pressure-sensitive adhesive: 4 μm / PET: 2 μm / acrylic pressure-sensitive adhesive: 4 μm).

  The PET tape P used as a protective layer in this evaluation was a PET (polyethylene terephthalate) tape having a thickness of 10 μm (PET: 6 μm / acrylic adhesive: 4 μm).

Example 1
In Example 1, the composite film 100 shown in FIGS. 1A and 1B was used as the sample S. The size of the composite film 100 is 50 mm × 50 mm. A graphite film G having a size of 50 mm × 50 mm was used for the first heat conductive layer 110. The double-sided pressure-sensitive adhesive film A having a size of 50 mm × 50 mm was used for the first adhesive layer 120. The evaluation results for the composite film 100 are shown in Table 1.

(Example 2)
In Example 2, the composite film 100A shown in FIG. The size of the composite film 100A is 50 mm × 50 mm. A graphite film G having a size of 50 mm × 50 mm was used for the first heat conductive layer 110. The double-sided pressure-sensitive adhesive film A having a size of 50 mm × 50 mm was used for the first adhesive layer 120. A PET tape P having a size of 50 mm × 50 mm was used for the protective layer 130. The evaluation results for the composite film 100A are shown in Table 1.

(Example 3)
In Example 3, the composite film 100B shown in FIG. The size of the composite film 100B is 50 mm × 50 mm. A graphite film G having a size of 50 mm × 50 mm was used for the first heat conductive layer 110. The double-sided pressure-sensitive adhesive film A having a size of 50 mm × 50 mm was used for the first adhesive layer 120 ′. A PET tape P having a size of 50 mm × 50 mm was used for the protective layer 140. The evaluation results for the composite film 100B are shown in Table 1.

Example 4
In Example 4, the composite film 100G shown in FIG. The size of the composite film 100G is 50 mm × 50 mm. A graphite film G having a size of 50 mm × 50 mm was used for the first heat conductive layer 110. The double-sided pressure-sensitive adhesive film A having a size of 50 mm × 50 mm was used for the first adhesive layer 120. A PET tape P having a size of 50 mm × 50 mm was used for the protective layer 130. The evaluation results for the composite film 100G are shown in Table 1.

(Comparative Example 1)
In Comparative Example 1, a composite film X having a size of 50 mm × 50 mm was used. The composite film X was produced by bonding one surface of the double-sided pressure-sensitive adhesive film A having no opening to one surface of the graphite film G having no opening. The composite film X was affixed to the support B via the other surface of the double-sided pressure-sensitive adhesive film A in a state where the central portion was disposed directly above the central portion of the heating element H. The evaluation results for the composite film X are shown in Table 1.

(Comparative Example 2)
In Comparative Example 2, a composite film Y having a size of 50 mm × 50 mm was used. The composite film Y is bonded to one surface of the PET tape T having no opening on one surface of the graphite film G having no opening, and both surfaces having no opening on the other surface of the graphite film G. One side of the adhesive film A was bonded together. The composite film Y was affixed to the support B via the other surface of the double-sided pressure-sensitive adhesive film A in a state where the central portion was disposed directly above the central portion of the heating element H. The evaluation results for the composite film Y are shown in Table 1.

(Comparative Example 3)
In Comparative Example 3, a composite film Z having a size of 50 mm × 50 mm was used. The composite film Z is bonded to one surface of a PET tape T having an opening of 10 mm × 10 mm in the center with one surface of a graphite film G having an opening of 10 mm × 10 mm in the center. One side of the double-sided pressure-sensitive adhesive film A having an opening having a size of 10 mm × 10 mm at the center was bonded to the other side of the film G to prepare it. That is, the composite film Z has an opening of 10 mm × 10 mm penetrating all layers in the thickness direction. The composite film Y was affixed to the support B via the other surface of the double-sided pressure-sensitive adhesive film A in a state where the center of the opening was disposed directly above the center of the heating element H. The evaluation results for the composite film Z are shown in Table 1.

  As described above, the composite film according to the present embodiment efficiently diffuses heat in the surface direction, and the opening that forms the sealed space functions as a heat insulating layer, so that the heat source generates heat and faces the heat source. A heat spot generated in the member can be more reliably suppressed. In particular, the composite films shown in Examples 1 to 3 exhibit an excellent effect in suppressing heat spots.

  As mentioned above, although this invention was demonstrated using embodiment, the technical scope of this invention is not limited to the range as described in the said embodiment. It will be apparent to those skilled in the art that various modifications or improvements can be added to the above-described embodiment. It is apparent from the scope of the claims that the embodiments added with such changes or improvements can be included in the technical scope of the present invention.

  The execution order of each process such as operations, procedures, steps, and stages in the composite film, device, and composite film manufacturing method shown in the claims, the specification, and the drawings is particularly “before”. It should be noted that “preceding” or the like is not specified, and that the output of the previous process can be realized in any order unless it is used in the subsequent process. Regarding the operation flow in the claims, the description, and the drawings, even if it is described using “first”, “next”, etc. for convenience, it means that it is essential to carry out in this order. It is not a thing.

DESCRIPTION OF SYMBOLS 10 Case 20 Board | substrate 22 Electronic component 100 Composite film 110 1st heat conductive layer 120 1st contact bonding layer 122 Opening 130 Protective layer 200 Device

Claims (28)

A first thermal conduction layer having a thermal conductivity in the plane direction higher than that in the thickness direction;
A composite film comprising: a first buffer layer laminated on one surface side of the first heat conductive layer and having an opening.   The heat spot suppressing film according to claim 1, wherein the opening is disposed at a position facing the heat source via the first heat conductive layer, thereby suppressing a heat spot generated in a member facing the heat source. Composite film.   The composite film according to claim 1, wherein the opening is sealed by attaching the first buffer layer to a surface of the member facing the heat source on the heat source side.   4. The composite film according to claim 1, wherein the first buffer layer is an adhesive layer that bonds a member facing a heat source and the first heat conductive layer. 5. The first buffer layer includes:
A protective layer for protecting the first buffer layer side surface of the first thermal conductive layer;
The composite film according to any one of claims 1 to 3, further comprising a member facing the heat source and an adhesive layer that adheres the protective layer.   The composite film according to any one of claims 1 to 5, wherein the opening penetrates the first buffer layer in a thickness direction.   The composite film according to claim 4, wherein the opening is provided in the adhesive layer.   The composite film according to claim 7, wherein the adhesive layer is a double-sided pressure-sensitive adhesive film.   The composite film according to claim 5, wherein the opening is provided in the protective layer.   The composite film according to any one of claims 7 to 9, wherein the opening penetrates a layer in which the opening is provided in a thickness direction.   The composite film according to claim 1, wherein the first buffer layer has a plurality of the openings arranged.   The composite film according to any one of claims 1 to 11, further comprising a protective layer that protects a surface of the first thermal conductive layer opposite to the surface on the first buffer layer side. The second buffer layer is laminated on the surface side opposite to the surface of the first buffer layer on the first heat conductive layer side, and the second heat conductive layer has a higher thermal conductivity in the plane direction than the thermal conductivity in the thickness direction,
13. The semiconductor device according to claim 1, further comprising: a second buffer layer that is laminated on a surface of the second heat conductive layer opposite to the surface on the first buffer layer side and that has an opening. Composite film as described in 1.   The composite film according to claim 13, wherein an area of the opening of the first buffer layer is different from an area of the opening of the second buffer layer.   The composite film according to claim 14, wherein an area of the opening of the first buffer layer is smaller than an area of the opening of the second buffer layer. The first buffer layer and the second buffer layer have a plurality of the openings,
The composite film according to claim 15, wherein a total area of the plurality of openings included in the first buffer layer is smaller than a total area of the plurality of openings included in the second buffer layer.   The composite film according to any one of claims 1 to 16, wherein the first heat conductive layer is a graphite film produced by heat-treating a polymer film. A heat source,
A housing that houses the heat source;
The composite film according to any one of claims 1 to 17, wherein the composite film is disposed between the heat source and an inner wall of the housing.
The first buffer layer is provided on the inner wall side of the housing from the first heat conductive layer,
The opening is a device disposed at a position facing the heat source.   The device according to claim 18, wherein the composite film is attached to the inner wall of the housing. Forming an opening in the double-sided adhesive film;
A method of manufacturing a composite film comprising: attaching the double-sided pressure-sensitive adhesive film in which the opening is formed to a heat conductive film having a heat conductivity in a surface direction higher than a heat conductivity in a thickness direction. A heat conductive layer having an opening penetrating in the thickness direction, the thermal conductivity in the plane direction being higher than the thermal conductivity in the thickness direction;
A first buffer layer laminated on one surface of the heat conducting layer;
A second buffer layer laminated on the other surface of the heat conductive layer,
A composite film in which the opening is sealed by the first buffer layer and the second buffer layer.   The composite film according to claim 21, wherein the composite film is a heat spot suppressing film that suppresses a heat spot generated in a member facing the heat source by disposing the opening at a position facing the heat source.   23. The composite film according to claim 21, wherein the first buffer layer has an adhesive layer that bonds a member facing a heat source and the heat conductive layer.   The composite film according to any one of claims 21 to 23, wherein the second buffer layer includes a protective layer that protects the heat conductive layer.   The composite film according to any one of claims 21 to 24, wherein the heat conductive layer is a graphite film produced by heat-treating a polymer film. A heat source,
A housing that houses the heat source;
The composite film according to any one of claims 21 to 25, which is disposed between the heat source and an inner wall of the housing.
The opening is a device disposed at a position facing the heat source.   27. The device according to claim 26, wherein the composite film is attached to the inner wall of the housing. A step of forming an opening penetrating in the thickness direction in the heat conductive film having a thermal conductivity in the plane direction higher than the thermal conductivity in the thickness direction;
A step of attaching a first film that closes the one surface side of the opening to the one surface of the heat conductive film in which the opening is formed;
A method of manufacturing a composite film, comprising: attaching a second film that closes the other surface side of the opening to the other surface of the heat conductive film in which the opening is formed.

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