JP6806330B2 - Thermally conductive adhesive sheet, its manufacturing method and electronic devices using it - Google Patents

Description

The present invention relates to a thermally conductive adhesive sheet, and more particularly to a thermally conductive adhesive sheet used for an electronic device, a method for producing the same, and an electronic device using the same.

Conventionally, a sheet-shaped heat radiating member having high thermal conductivity has been used inside an electronic device or the like in order to release heat or control the flow of heat in a specific direction. Examples of electronic devices include thermoelectric conversion devices, photoelectric conversion devices, semiconductor devices such as large-scale integrated circuits, and the like.

In recent years, in semiconductor devices, with the miniaturization and high density of the semiconductor devices, the heat generated from the inside during operation becomes higher, and when heat dissipation is insufficient, the characteristics of the semiconductor device itself deteriorate. However, it sometimes causes a malfunction, which may eventually lead to the destruction or shortening of the life of the semiconductor device. In such a case, as a method for efficiently dissipating the heat generated from the semiconductor device to the outside, a heat radiating sheet having excellent thermal conductivity is provided between the semiconductor device and the heat sink (metal member). ..
Further, among such electronic devices, in the thermoelectric conversion device, although it is related to the control of heat dissipation described above, the heat applied to one side of the thermoelectric element is subjected to a temperature difference in the thickness direction inside the thermoelectric element. If the power is controlled to be large, the power obtained will be large. Therefore, heat dissipation is selectively controlled in a specific direction by using a sheet-shaped heat radiating member (a temperature difference is efficiently applied to the inside of the thermoelectric element). It is being considered. Patent Document 1 discloses a thermoelectric conversion element having a structure as shown in FIG. 7. That is, a P-type thermoelectric element 41 and an N-type thermoelectric element 42 are connected in series, thermoelectromotive force extraction electrodes 43 are arranged at both ends thereof to form a thermoelectric conversion module 46, and both sides of the thermoelectric conversion module 46 are formed. Flexible film-like substrates 44 and 45 made of two types of materials having different thermal conductivitys are provided. The film-shaped substrates 44 and 45 are provided with materials (polyimide) 47 and 48 having low thermal conductivity on the joint surface side with the thermoelectric conversion module 46, and are provided on the side opposite to the joint surface of the thermoelectric conversion module 46. Materials (copper) 49, 50 having high thermal conductivity are provided so as to be located on a part of the outer surface of the substrates 44, 45.

Further, Patent Document 2 discloses a thermoelectric conversion module having the structure shown in FIG. 8, in which electrodes 54 also serving as high thermal conductivity members are embedded in members 51 and 52 having low thermal conductivity, and these are the thermoelectric element 53. On the other hand, it is arranged via the conductive adhesive layer 55 and the insulating adhesive layer 56.
Further, in Patent Document 3, as shown in FIG. 9 in a cross-sectional configuration diagram of the thermoelectric conversion element (arrangement of the thermoelectric element 61 in the depth direction and internal electrode arrangement are omitted), one of the thermoelectric elements 61. An insulating base layer 65 is directly arranged on the surface via an adhesive layer 67, and an insulating base layer 65 is directly arranged on the other surface, and a pattern layer composed of a metal layer 63 and a resin layer 64 is placed on the base layer 65. The flexible substrates 62 and 66 having the same are disclosed.

Japanese Patent No. 3981738 Japanese Unexamined Patent Publication No. 2011-35203 Japanese Unexamined Patent Publication No. 2008-182160

As described above, especially in electronic devices mainly for semiconductor devices, a heat radiating sheet that can dissipate heat to the outside more efficiently, and in addition to being excellent in thermal conductivity, heat is directed in a specific direction. There is a demand for a thermally conductive sheet having a function of selectively dissipating heat and generating a temperature gradient inside the electronic device. However, when the present inventors have applied a heat conductive adhesive sheet composed of a high heat conductive part and a low heat conductive part to the thermoelectric element of the thermoelectric conversion device as described above and examined it, the heat conductive adhesion We have found a new problem that the dimensional accuracy of the pattern of the high heat conductive part and the low heat conductive part of the sheet is poor and a predetermined temperature difference cannot be obtained. The reason why the dimensional accuracy deteriorates is the difference in internal stress including curing shrinkage between the high thermal conductive portion and the low thermal conductive portion constituting the heat conductive adhesive sheet.

In view of the above problems, the present invention aims to improve the dimensional accuracy of the high thermal conductive portion and the low thermal conductive portion of the thermally conductive adhesive sheet, and to reduce the thermal conductivity of the low thermal conductive portion, and further, the electronic device is provided with an adhesive layer. It is an object of the present invention to provide a thermally conductive adhesive sheet, a method for producing the same, and an electronic device using the same, which can be easily laminated without any problem and can impart a sufficient temperature difference to the inside of the electronic device.

As a result of diligent studies to solve the above problems, the present inventors have composed a heat conductive adhesive sheet from a high heat conductive part and a low heat conductive part to which adhesiveness is imparted, and a specific amount of the low heat conductive part. It contains a (% by volume) hollow filler, and the high and low thermal conductivity parts independently constitute all the thickness of the thermal conductive adhesive sheet, or at least one of them is a part of the thickness of the thermal conductive adhesive sheet. The present invention has been completed by finding that the above-mentioned problems can be solved by using a heat conductive adhesive sheet constituting the above.
That is, the present invention provides the following (1) to (12).
(1) A thermally conductive adhesive sheet having a high thermal conductive portion and a low thermal conductive portion, wherein the high thermal conductive portion and the low thermal conductive portion have adhesiveness, and a hollow filler is applied to the low thermal conductive portion. It is contained in an amount of 20 to 90% by volume in the total volume of the low heat conductive part, and the high heat conductive part and the low heat conductive part independently constitute all the thicknesses of the heat conductive adhesive sheet, or at least one of them is heat conductive. A thermally conductive adhesive sheet that forms part of the thickness of the adhesive sheet.
(2) The heat conductive adhesive sheet according to (1) above, wherein the high thermal conductive portion and the low thermal conductive portion are formed from an adhesive resin composition.
(3) The heat conductive adhesive sheet according to (2) above, wherein the adhesive resin composition contains at least one of a thermosetting resin and an energy ray curable resin.
(4) The heat conductive adhesive sheet according to (3) above, wherein the thermosetting resin is a silicone resin or a urethane resin.
(5) The thermally conductive adhesive sheet according to (2) above, wherein the adhesive resin composition of the high thermal conductive portion contains a thermally conductive filler and / or a conductive carbon compound.
(6) The thermally conductive adhesive sheet according to (5) above, wherein the thermally conductive filler contains at least one selected from the group consisting of metal oxides, metal nitrides, and metals.
(7) The heat conductive adhesive sheet according to (1) above, wherein the hollow filler is a glass hollow filler or a silica hollow filler.
(8) The thermally conductive adhesive sheet according to (7) above, wherein the true density of the hollow glass filler and the hollow silica filler is 0.1 to 0.6 g / cm ³ .
(9) The heat conductive adhesion according to any one of (2) to (6) above, wherein the composite curing shrinkage rate of the adhesive resin composition of the high thermal conductive portion and the low thermal conductive portion is 2% or less. Sheet.
(10) The thermal conductivity of the high thermal conductivity portion of the heat conductive adhesive sheet is 0.5 (W / m · K) or more, and the thermal conductivity of the low thermal conductivity portion is less than 0.5 (W / m · K). The thermally conductive adhesive sheet according to any one of (1) to (9) above.
(11) An electronic device using the heat conductive adhesive sheet according to any one of (1) to (10) above.
(12) The method for producing a thermally conductive adhesive sheet according to any one of (1) to (10) above, wherein a highly thermally conductive portion formed from the adhesive resin composition is formed on the release sheet. A method for producing a thermally conductive adhesive sheet, which comprises a step of forming a low thermal conductive portion formed from an adhesive resin composition.

According to the heat conductive adhesive sheet of the present invention, the dimensional accuracy of the high thermal conductive portion and the low thermal conductive portion of the thermally conductive adhesive sheet is improved, the thermal conductivity of the low thermal conductive portion is lowered, and the adhesive is applied to the electronic device. It is possible to provide a thermally conductive adhesive sheet, a method for producing the same, and an electronic device using the same, which can be easily laminated without interposing a layer and can impart a sufficient temperature difference to the inside of the electronic device. In addition, since no adhesive layer is required, the productivity of the electronic device is high, leading to low cost.

It is a perspective view which shows an example of the heat conductive adhesive sheet of this invention. It is sectional drawing which shows various examples of the thermal conductive adhesive sheet of this invention. It is sectional drawing which shows an example of the thermoelectric conversion device when the heat conductive adhesive sheet of this invention is attached to the thermoelectric conversion module. An example of a perspective view in which the heat conductive adhesive sheet and the thermoelectric conversion module of the present invention are disassembled for each component is shown, and (a) is a heat conductive adhesive sheet directly provided on the thermoelectric element on the support surface side of the thermoelectric conversion module. (B) is a perspective view of the thermoelectric conversion module, and (c) is a perspective view of a heat conductive adhesive sheet provided on the back surface side of the support of the thermoelectric conversion module. It is explanatory drawing of the structure for measuring the temperature difference between the high heat conductive part and the low heat conductive part of the heat conductive adhesive sheet of this invention, (a) is a heat conductive adhesive sheet, (b) is an adherend. It is a perspective view of the glass substrate used as. It is a perspective view of the thermoelectric conversion module used in the Example of this invention. It is sectional drawing which shows an example of the structure of the conventional thermoelectric conversion device. It is sectional drawing which shows another example of the structure of the conventional thermoelectric conversion device. It is sectional drawing which shows still another example of the structure of the conventional thermoelectric conversion device.

[Thermal conductive adhesive sheet]
The thermally conductive adhesive sheet of the present invention is a thermally conductive adhesive sheet having a high thermal conductive portion and a low thermal conductive portion, and the high thermal conductive portion and the low thermal conductive portion have adhesiveness and a hollow filler is provided. , The low thermal conductive portion contains 20 to 90% by volume in the total volume of the low thermal conductive portion, and the high thermal conductive portion and the low thermal conductive portion independently constitute all the thicknesses of the thermally conductive adhesive sheet, or their At least one of them is a heat conductive adhesive sheet which constitutes a part of the thickness of the heat conductive adhesive sheet.

The configuration of the heat conductive adhesive sheet of the present invention will be described with reference to the drawings.

FIG. 1 is a perspective view showing an example of a heat conductive adhesive sheet of the present invention. The heat conductive adhesive sheet 1 is composed of high heat conductive parts 4a and 4b and low heat conductive parts 5a and 5b, and these are arranged alternately. The arrangement of the high thermal conductive portion and the low thermal conductive portion (hereinafter, may be referred to as “thickness configuration”) constituting the heat conductive adhesive sheet is not particularly limited as described below.
FIG. 2 shows various examples of cross-sectional views (including arrangement) of the heat conductive adhesive sheet of the present invention. FIG. 2A is a cross-sectional view of FIG. 1, in which the high thermal conductive portion 4 and the low thermal conductive portion 5 independently constitute all the thicknesses of the heat conductive adhesive sheet. Further, in FIGS. 2B and 2D, the low thermal conductive portion 5 constitutes a part of the thickness of the thermally conductive adhesive sheet. Further, in FIGS. 2 (c) and 2 (e), the high thermal conductive portion 4 constitutes a part of the thickness of the thermal conductive adhesive sheet. The thickness configuration of the thermally conductive adhesive sheet can be appropriately selected according to the specifications of the electronic device to be applied. For example, from the viewpoint of selectively dissipating heat in a specific direction, for example, it is preferable to select the thickness configuration of (a) to (e) of FIG. 2, and the thickness configuration of (a) of FIG. Is even more preferable.
Further, from the viewpoint of efficiently dissipating the heat generated from the inside of the electronic device to the outside, for example, it is preferable to select the thickness configuration of FIGS. 2 (a) to 2 (e) according to the specifications of the electronic device. At this time, if the volume of the high thermal conductive portion is large and the contact area with respect to the device surface to be applied is large, heat dissipation can be efficiently controlled.

<Low heat conduction part>
The low thermal conductive portion of the present invention is formed from a resin composition containing a hollow filler and an adhesive resin described later. By containing the hollow filler, the curing shrinkage rate of the low heat conductive part is suppressed, and by reducing the difference from the curing shrinkage rate of the high heat conductive part, the composite curing shrinkage rate described later is reduced, resulting in high heat. It is possible to suppress deterioration of the dimensional accuracy of each pattern of the conductive portion and the low thermal conductive portion.
The shape of the low thermal conductive portion is not particularly limited and can be appropriately changed according to the specifications of the electronic device and the like described later. Here, the low thermal conductivity portion of the present invention refers to one having a lower thermal conductivity than the high thermal conductivity portion.

The hollow filler is not particularly limited, and known ones can be used. For example, an inorganic hollow body which is a balloon (hollow body) such as a glass balloon, a silica balloon, a silas balloon, a fly ash balloon, or a metal silicate. Examples of the filler include organic resin-based hollow fillers that are balloons (hollow bodies) such as acrylonitrile, vinylidene chloride, phenol resin, epoxy resin, and urea resin. The hollow filler may be used alone or in combination of two or more. Among these, a glass hollow filler or a silica hollow filler, which is an inorganic hollow filler, is preferable because the thermal conductivity of the substance itself is relatively low among the metal oxides, and from the viewpoint of volume resistivity and cost. Specifically, the hollow glass filler is, for example, Glass Bubbles (soda lime borosilicate glass) manufactured by Sumitomo 3M Ltd., and the hollow silica filler is, for example, Sirinax (registered) manufactured by Nittetsu Mining Co., Ltd. Trademark) and the like.
The "hollow filler" in the present invention has an outer shell having a filler as a constituent material, and has a hollow structure inside (the inside may be filled with a gas such as an inert gas in addition to air. A filler that is (may be vacuum), and the hollow structure is not particularly limited. For example, the hollow structure may be a sphere or an ellipsoid, and there are a plurality of hollow structures. You may.

The shape of the hollow filler is not particularly limited, but when it is attached to the electronic device, element, etc. to which it is applied, the electrical characteristics of the electronic device, element, etc. are not impaired by their contact or mechanical damage. It may be in any shape, for example, plate-shaped (including scaly), spherical, needle-shaped, rod-shaped, or fibrous.

The size of the hollow filler is preferably 0.1 to 200 μm, more preferably 1 to 100 μm, for example, from the viewpoint of uniformly dispersing the hollow filler in the thickness direction of the low thermal conductive portion and lowering the thermal conductivity. , 10 to 80 μm is more preferable, and 20 to 50 μm is particularly preferable. If the average particle size of the hollow filler is within this range, the particles are less likely to agglomerate and can be uniformly dispersed. Further, the filling density of the low thermal conductive portion becomes sufficient, and the low thermal conductive portion does not become brittle at the material interface. The average particle size can be measured by, for example, the Coulter counter method.

The content of the hollow filler is appropriately adjusted according to the particle shape thereof, and is 20 to 90% by volume, preferably 40 to 80% by volume, and more preferably 50 to 70% by volume in the adhesive resin composition. If the content of the hollow filler is less than 20% by volume, the curing shrinkage becomes large and the pattern dimensional accuracy of the high thermal conductive portion and the low thermal conductive portion deteriorates. Further, if the content of the hollow filler exceeds 90% by volume, the mechanical strength of the low thermal conductive portion cannot be maintained. When the content of the hollow filler is within this range, curing shrinkage is effectively suppressed, heat dissipation characteristics, folding resistance, and bending resistance are excellent, and the mechanical strength of the low thermal conductive portion is maintained.

True density of the hollow filler is preferably from 0.1 to 0.6 g / cm ^3, more preferably 0.2-0.5 g / cm ^3, more preferably 0.3~0.4g / cm ^3. When the true density of the hollow filler is within this range, the heat insulating property and the pressure resistance are excellent, the hollow filler does not break when the low thermal conductive portion is formed, and the low thermal conductivity of the low thermal conductive portion is not impaired.
Here, the "true density" is the density measured by the pycnometer method (the gas phase method based on Archimedes' principle). For example, it can be measured using a pycnometer (gas phase substitution type true densitometer, for example, AccuPycII 1340 manufactured by Micromeritics).

(Adhesive resin)
The adhesive resin used in the present invention is not particularly limited, but any resin can be appropriately selected from those used in the field of electronic components and the like, for example, a thermosetting resin, an energy ray curable resin and the like. Can be mentioned.

Examples of the thermosetting resin include epoxy resin, melamine resin, urea resin, phenol resin, silicone resin, urethane resin, polyimide resin, benzoxazine resin, thermosetting acrylic resin, unsaturated polyester resin and the like. Among these, urethane resin and silicone resin are preferable from the viewpoint of excellent heat resistance and high adhesive strength.
As the urethane resin, a reaction product of a hydroxyl group-containing compound and a polyisocyanate compound, for example, a polyurethane obtained by reacting a short-chain glycol or a short-chain ether with an isocyanate compound as a hard segment, and a long-chain glycol or a long segment as a soft segment. Examples thereof include a linear multi-block copolymer of polyurethane obtained by the reaction of a chain ether and an isocyanate compound. Examples thereof include a reaction product (cured product) of a urethane prepolymer and a polyisocyanate compound.
As the silicone resin, a thermosetting addition reaction type silicone resin can be used. Examples of the addition reaction type silicone resin include at least one selected from polyorganosiloxane having an alkenyl group as a functional group in the molecule. Preferred polyorganosiloxane having an alkenyl group as a functional group in the above molecule includes polydimethylsiloxane having a vinyl group as a functional group, polydimethylsiloxane having a hexenyl group as a functional group, and a mixture thereof. ..

When the thermosetting resin is used, it is preferable to use a curing agent, a curing accelerator, a curing retarder, a curing catalyst, or the like in combination as an auxiliary agent.
Examples of the curing agent include compounds having two or more functional groups in one molecule that can react with the functional groups of the thermosetting resin component. Examples of the curing agent for the epoxy resin include a phenol-based curing agent, an alcohol-based curing agent, an amine-based curing agent, and an aluminum chelate-based curing agent. Moreover, as a curing agent for a silicone resin, a hydrosilyl type curing agent and the like can be mentioned.
As the curing accelerator, for example, tertiary amines such as triethylenediamine and benzyldimethylamine; imidazoles such as 2-methylimidazole and 2-phenylimidazole; organic phosphines such as tribritzphosphin and diphenylphosphine; tetraphenyl. Examples thereof include tetraphenylborone salts such as phosphonium tetraphenylborate and triphenylphosphine tetraphenylborate.
Examples of the curing retarder include a hydrosilylation reaction controller and the like. Examples of the curing catalyst include platinum-based catalysts, palladium-based catalysts, rhodium-based catalysts and the like.
The content of the above-mentioned auxiliary agent varies depending on the type of the thermosetting resin, but is 10 to 90 parts by mass, preferably 20 to 80 parts by mass, more preferably 20 parts by mass with respect to 100 parts by mass of the thermosetting resin. It is 30 to 70 parts by mass.

Examples of the energy ray-curable resin include compounds having one or more polymerizable unsaturated bonds, such as compounds having an acrylate-based functional group. Examples of the compound having one polymerizable unsaturated bond include ethyl (meth) acrylate, ethylhexyl (meth) acrylate, styrene, methylstyrene, N-vinylpyrrolidone and the like. Examples of the compound having two or more polymerizable unsaturated bonds include polymethylol propantri (meth) acrylate, hexanediol (meth) acrylate, tripropylene glycol di (meth) acrylate, and diethylene glycol di (meth) acrylate. , Pentaerythritol tri (meth) acrylate, dipentaerythritol hexa (meth) acrylate, 1,6-hexanediol di (meth) acrylate, neopentyl glycol di (meth) acrylate and other polyfunctional compounds, variants thereof, and , Reaction products of these polyfunctional compounds and (meth) acrylate and the like (for example, poly (meth) acrylate ester of polyhydric alcohol) and the like. In addition, in this specification, (meth) acrylate means methacrylate and acrylate.

In addition to the above compounds, relatively low molecular weight polyester resins, polyether resins, acrylic resins, epoxy resins, urethane resins, silicone resins, polybutadiene resins and the like having a polymerizable unsaturated bond are also used as the energy ray curable resin. be able to.

It is preferable to use a photopolymerization initiator in combination with the energy ray-curable resin. The photopolymerization initiator used in the present invention is contained in the adhesive resin composition containing the energy ray-curable resin, and can cure the energy ray-curable resin under ultraviolet rays. Examples of the photopolymerization initiator include benzoin, benzoin methyl ether, benzoin ethyl ether, benzoin isopropyl ether, benzoin-n-butyl ether, benzoin isobutyl ether, acetophenone, dimethylaminoacetophenone, 1-hydroxy-cyclohexyl-phenylketone, 2, 2-Dimethoxy-2-phenylacetophenone, 2,2-diethoxy-2-phenylacetophenone, 2-hydroxy-2-methyl-1-phenylpropan-1-one, 2-aminoanthraquinone, 2-methylthioxanthone, 2-ethyl Thioxanthone, 2-chlorothioxanthone, 2,4-dimethylthioxanthone, 2,4-diethylthioxanthone, benzyldimethylketal, acetophenonedimethylketal, p-dimethylamine benzoic acid ester and the like can be used.
One type of photopolymerization initiator may be used alone, or two or more types may be used in combination. The blending amount is usually selected in the range of 0.2 to 10 parts by mass with respect to 100 parts by mass of the energy ray-curable resin.
The mass average molecular weight of the adhesive resin used in the present invention is usually several hundred to several million.

<Other ingredients>
The adhesive resin composition may be used, if necessary, within an appropriate range, for example, a cross-linking agent, a filler, a plasticizer, an antioxidant, an antioxidant, an ultraviolet absorber, a colorant such as a pigment or a dye, and adhesion. Additives such as an imparting agent, an antistatic agent, and a coupling agent, and a non-adhesive resin may be contained.

Examples of the non-adhesive resin include polyester resin, urethane resin, silicone resin, rubber polymer, polyolefin resin, styrene resin, amide resin, cyclic olefin resin, vinyl chloride resin, polyimide resin, polycarbonate resin, polysulfone resin and the like. Be done.

<High heat conduction part>
The shape of the high thermal conductive portion is not particularly limited as in the shape of the low thermal conductive portion, and can be appropriately changed according to the specifications of the electronic device and the like described later. Here, the high thermal conductivity portion of the present invention refers to one having a higher thermal conductivity than the low thermal conductivity portion.
The high thermal conductivity portion is not particularly limited as long as it is formed of an adhesive resin composition and has a higher thermal conductivity than the low thermal conductivity portion.

Examples of the adhesive resin include similar resins such as the thermosetting resin and the energy curable resin used for the low heat conductive portion described above. Usually, the same resin as the low thermal conductive part is used from the viewpoint of mechanical properties, adhesion, etc.

The high thermal conductivity portion is preferably formed from a resin composition containing the adhesive resin and a thermally conductive filler and / or a conductive carbon compound in order to adjust to a desired thermal conductivity described later.
Hereinafter, the thermally conductive filler and the conductive carbon compound may be referred to as "material for adjusting thermal conductivity".

(Thermal conductive filler and conductive carbon compound)
The thermally conductive filler is not particularly limited, but may be derived from metal oxides such as silica, alumina and magnesium oxide, metal nitrides such as silicon nitride, aluminum nitride, magnesium nitride and boron nitride, and metals such as copper and aluminum. At least one selected, and as the conductive carbon compound, at least one selected from carbon black, carbon nanotubes (CNT), graphene, carbon nanofibers and the like is preferable. These thermally conductive fillers and conductive carbon compounds can be used alone or in combination of two or more. Among these, the heat of metal oxides such as silica, alumina and magnesium oxide, and metal nitrides such as silicon nitride, aluminum nitride, magnesium nitride and boron nitride is likely to fall within the range of volumetric resistance described later. Conductive fillers are preferred. Further, it is more preferable that the thermally conductive filler contains a metal oxide and a metal nitride. Further, when the metal oxide and the metal nitride are contained as the heat conductive filler, the mass ratio of the metal oxide and the metal nitride is preferably 10:90 to 90:10, preferably 20:80 to 80:20. More preferably, 50:50 to 75:25 is even more preferable.
The shape of the substance for adjusting the thermal conductivity is not particularly limited, but when it is attached to the electronic device, element, etc. to which it is applied, due to contact or mechanical damage to them, the electrical characteristics of the electronic device, element, etc. Any shape may be used as long as the shape is not impaired, and may be plate-shaped (including scale-shaped), spherical, needle-shaped, rod-shaped, or fibrous. The above-mentioned "hollow filler" is not included in the heat conductive filler used for the high heat conductive portion.

The size of the thermal conductivity adjusting substance is, for example, an average particle diameter of 0.1 to 200 μm from the viewpoint of uniformly dispersing the thermal conductivity adjusting substance in the thickness direction of the high thermal conductivity portion to improve the thermal conductivity. Preferably, 1 to 100 μm is more preferable, 5 to 50 μm is further preferable, and 10 to 30 μm is particularly preferable. The average particle size can be measured by, for example, the Coulter counter method. If the average particle size of the substance for adjusting the thermal conductivity is within this range, the thermal conductivity inside each substance will not be reduced, and as a result, the thermal conductivity of the high thermal conductivity portion will be improved. In addition, the particles are less likely to agglomerate and can be uniformly dispersed, the filling density of the high thermal conductive portion is sufficient, and the high thermal conductive portion does not become brittle at the material interface.

The content of the substance for adjusting the thermal conductivity is appropriately adjusted according to the desired thermal conductivity, and is preferably 40 to 99% by mass, more preferably 50 to 95% by mass, and 50 to 80% in the adhesive resin composition. Mass% is particularly preferred. When the content of the substance for adjusting the thermal conductivity is within this range, the heat dissipation characteristics, the folding resistance, and the bending resistance are excellent, and the strength of the high thermal conductivity portion is maintained.

<Other ingredients>
Similar to the low thermal conductive portion, the high thermal conductive portion may further contain the same type of additive within an appropriate range, if necessary.

The thickness of each layer of the high thermal conductive portion and the low thermal conductive portion is preferably 1 to 200 μm, more preferably 3 to 100 μm. Within this range, heat can be selectively dissipated in a specific direction. Further, the thickness of each layer of the high thermal conductive portion and the low thermal conductive portion may be the same or different.
The width of each layer of the high thermal conductive portion and the low thermal conductive portion is appropriately adjusted and used according to the specifications of the electronic device to be applied, but is usually 0.01 to 3 mm, preferably 0.1 to 2 mm, and more preferably 0. It is 5 to 1.5 mm. Within this range, heat can be selectively dissipated in a specific direction. Further, the widths of the respective layers of the high thermal conductive portion and the low thermal conductive portion may be the same or different.

The thermal conductivity of the high thermal conductivity portion may be sufficiently higher than that of the low thermal conductivity portion, and the thermal conductivity is preferably 0.5 (W / m · K) or more, preferably 1.0 (W / m · K) or more. Is more preferable, and 1.3 (W / m · K) or more is further preferable. The upper limit of the thermal conductivity of the high thermal conductivity portion is not particularly limited, but is usually preferably 2000 (W / m · K) or less, and more preferably 500 (W / m · K) or less.

The thermal conductivity of the low thermal conductivity portion is preferably less than 0.5 (W / m · K), more preferably 0.3 (W / m · K) or less, and 0.25 (W / m · K) or less. More preferred. When the conductivity of the high thermal conductive portion and the low thermal conductive portion is within the above range, heat can be selectively dissipated in a specific direction.

The composite curing shrinkage of the adhesive resin composition of each of the high thermal conductive portion and the low thermal conductive portion is preferably 2% or less, and more preferably 1% or less. When the composite curing shrinkage rate is within this range, the pattern dimensional accuracy of the high thermal conductive portion and the low thermal conductive portion is improved, heat is selectively dissipated in a specific direction, and a sufficient temperature difference is generated inside the electronic device or the like. Can be granted.
The above-mentioned "composite curing shrinkage rate" in the present invention is derived from, for example, a stripe pattern and an adhesive resin composition constituting the low thermosetting portion, which is formed from the adhesive resin composition constituting the high thermal conductive portion. The dimensional change of the formed composite pattern consisting of, for example, a stripe pattern (see, for example, FIGS. 1 and 2 (a)) was measured before and after curing, and was defined and calculated from the following formula.
Composite curing shrinkage rate (%) = [(total width in stripe pattern pitch direction before curing-total width in stripe pattern pitch direction after curing) / total width in stripe pattern pitch direction before curing] x 100
Specifically, in the stripe pattern (adhesive resin composition) group having the specifications shown below, the width of the high thermal conductive portion stripe pattern formed from the adhesive resin composition for forming the high thermal conductive portion and the width of the low thermal conductive portion in the pitch direction. The total width (that is, the entire width of the stripe pattern in the pitch direction) with the width in the pitch direction of the low thermal conductivity part stripe pattern formed from the adhesive resin composition for forming is measured by a digital multimeter (manufactured by Nippon Kogaku Co., Ltd.) before and after curing. , NRM-S3-XY type) was used for measurement.
The specifications of the dimensional measurement sample are as follows.
-Striped pattern (adhesive resin composition) group: 100 mm x 100 mm, thickness 100 μm
-High thermal conductivity part: stripe width 1 mm, length 100 mm, thickness 100 μm
-Low thermal conductivity part: stripe width 1 mm, length 100 mm, thickness 100 μm
-High thermal conductivity (stripes) and low thermal conductivity (stripes) are arranged alternately in the pitch direction (however, the space between the stripes is zero).
Further, for example, as shown in FIGS. 2 (b) to 2 (e), the thickness configurations of the heat conductive adhesive sheets are different (in FIGS. 1 and 2 (a), the thicknesses of the high heat conductive portion and the low heat conductive portion are different. Including cases where they are different from each other; however, at least one of the high heat conductive part and the low heat conductive part has a stripe pattern), the specifications of the sample for dimensional measurement are that the thickness composition of the heat conductive adhesive sheet is maintained and the heat is high. Only the thickness of each layer of the conductive portion and the low thermal conductive portion was increased or decreased to the same thickness, respectively, so that the total thickness of the entire layer was 100 μm.

The storage elastic modulus at 150 ° C. after curing of the high thermal conductive portion is preferably 0.1 MPa or more, more preferably 0.15 MPa or more, still more preferably 1 MPa or more. Further, the storage elastic modulus at 150 ° C. after curing of the low thermal conductive portion is preferably 0.1 MPa or more, more preferably 0.15 MPa or more, still more preferably 1 MPa or more. When the storage elastic modulus at 150 ° C. after curing of the high thermal conductive portion and the low thermal conductive portion is 0.1 MPa or more, the heat conductive adhesive sheet is suppressed from being excessively deformed, and stable heat dissipation can be achieved. it can. The upper limit of the storage elastic modulus at 150 ° C. is not particularly limited, but is preferably 500 MPa or less, more preferably 100 MPa or less, and even more preferably 50 MPa or less.
By adjusting the selection and combination of the adhesive resin in the resin composition described above, the types of the thermally conductive filler and the conductive carbon compound, and the amount thereof, 150 after curing of the high thermal conductive portion and the low thermal conductive portion. The storage elastic modulus at ° C can be adjusted.
The storage elastic modulus at 150 ° C. is raised to 150 ° C. at an initial temperature of 15 ° C. and a heating rate of 3 ° C./min by a dynamic elastic modulus measuring device (manufactured by TA Instruments, model name “DMAQ800”). It is a value measured at a frequency of 11 Hz after warming.
Further, since the heat conductive adhesive sheet is attached to the electronic device without passing through the adhesive layer, it is preferable that the heat conductive adhesive sheet has a function of preventing electrical connection. Therefore, the volume resistivity of the high thermal conductive portion and the low thermal conductive portion is preferably 1 × 10 ¹⁰ Ω · cm or more, and more preferably 1.0 × 10 ¹³ Ω · cm or more.
The volume resistivity is a value measured by a resistivity meter (MCP-HT450, manufactured by Mitsubishi Chemical Analytech Co., Ltd.) after leaving the thermally conductive adhesive sheet in an environment of 23 ° C. and 50% RH for one day.

In the heat conductive adhesive sheet, for example, as shown in FIGS. 1 and 2 (a), when the high heat conductive portion and the low heat conductive portion independently constitute all the thicknesses of the heat conductive adhesive sheet, the heat is said. On the outer surface of the conductive adhesive sheet, the step between the high thermal conductive portion and the low thermal conductive portion is preferably 10 μm or less, more preferably 5 μm or less, and further preferably substantially nonexistent.

At least one of the high thermal conductive portion and the low thermal conductive portion constitutes a part of the thickness of the base material. For example, in the case of FIGS. 2B and 2C, the step between the high thermal conductive portion and the low thermal conductive portion is It is preferably 10 μm or less, more preferably 5 μm or less, and further preferably substantially nonexistent. Further, in the case of FIGS. 2 (d) and 2 (e) in which a predetermined step is provided between the high thermal conductive portion and the low thermal conductive portion, the thickness of the base material is set to the thickness of the high thermal conductive portion and the low thermal conductive portion. The step between the high thermal conductive portion and the low thermal conductive portion at that time is preferably 10 to 90% with respect to the thickness. Further, in the heat conductive adhesive sheet, the volume ratio of the high heat conductive part and the low heat conductive part is preferably 10:90 to 90:10, more preferably 20:80 to 80:20, and 30 : 70 to 70:30 is more preferable.

<Release sheet>
The thermally conductive adhesive sheet may have a release sheet on one side or both sides. Examples of the release sheet include paper such as glassin paper, coated paper, and laminated paper, and various plastic films coated with a release agent such as silicone resin and fluororesin. The thickness of the release sheet is not particularly limited, but is usually 10 to 200 μm. It is preferable to use a plastic film as the supporting base material used for the release sheet used in the present invention.

<Electronic device>
The electronic device using the heat conductive adhesive sheet of the present invention is not particularly limited, and examples thereof include a thermoelectric conversion device, a photoelectric conversion device, and a semiconductor device such as a large-scale integrated circuit from the viewpoint of heat control such as heat dissipation. In particular, the heat conductive adhesive sheet can be attached to the thermoelectric conversion module of the thermoelectric conversion device to selectively dissipate heat in a specific direction, which leads to further improvement of thermoelectric performance. It is preferably used.
The heat conductive adhesive sheet may be laminated on one side of the electronic device, or may be laminated on both sides. Select as appropriate according to the specifications of the electronic device.
Hereinafter, the case of a thermoelectric conversion device as an electronic device will be described as an example.

(Thermoelectric conversion device)
A thermoelectric conversion device is an electronic device that can easily obtain electric power by applying a temperature difference inside a thermoelectric conversion element that performs mutual energy conversion between heat and electricity.
FIG. 3 is a cross-sectional view showing an example of a thermoelectric conversion device when the heat conductive adhesive sheet of the present invention having the configuration of FIG. 2A is attached to a thermoelectric conversion module. The thermoelectric conversion device 10 shown in FIG. 3 is composed of a thin-film P-type thermoelectric element 11 made of a P-type material and a thin-film N-type thermoelectric element 12 made of an N-type material on a support (not shown). The thermoelectric conversion module 16 having a thermoelectric conversion element and further provided with an electrode 13, the heat conductive adhesive sheet 1A attached to the first surface 17 of the thermoelectric conversion module 16, and further the first surface 17 It is composed of a heat conductive adhesive sheet 1B attached to the second surface 18 on the opposite side.

The heat conductive adhesive sheet 1A has high heat conductive portions 14a and 14b and low heat conductive parts 15a, 15b and 15c, and the high heat conductive parts 14a and 14b and the low heat conductive parts 15a, 15b and 15c have adhesiveness. And they constitute the outer surface of the thermally conductive adhesive sheet. Further, the heat conductive adhesive sheet 1B has high heat conductive portions 14'a, 14'b, 14'c and low heat conductive parts 15'a, 15'b, and the high heat conductive parts 14'a, 14'. b, 14'c and the low thermal conductive portions 15'a, 15'b have adhesiveness, and they constitute the outer surface of the thermal conductive adhesive sheet.

FIG. 4 shows an example of a perspective view of the heat conductive adhesive sheet and the thermoelectric conversion module of the present invention disassembled for each component. 4A and 4B are perspective views of a heat conductive adhesive sheet 1A directly provided on the thermoelectric elements 11 and 12 on the surface side of the support 19 of the thermoelectric conversion module 16, and FIG. 4B is a perspective view of the thermoelectric conversion module 16. It is a perspective view, (c) is the perspective view of the heat conductive adhesive sheet 1B provided on the back surface side of the support 19 of a thermoelectric conversion module 16.
By adopting the above configuration, heat can be efficiently diffused from the heat conductive adhesive sheet 1A and the heat conductive adhesive sheet 1B. Further, the high thermal conductive portions 14a and 14b of the heat conductive adhesive sheet 1A and the high thermal conductive portions 14'a, 14'b and 14'c of the heat conductive adhesive sheet 1B are laminated by shifting their positions so as not to face each other. By doing so, heat can be selectively dissipated in a specific direction. As a result, a temperature difference can be efficiently applied to the thermoelectric conversion module, and a thermoelectric conversion device having high power generation efficiency can be obtained.

The thermoelectric conversion module 16 used in the present invention is composed of, for example, a P-type thermoelectric element 11, an N-type thermoelectric element 12, and an electrode 13 as shown in FIG. 4 (b). The P-type thermoelectric element 11 and the N-type thermoelectric element 12 are formed in a thin film so as to be connected in series, and are electrically connected to each other via an electrode 13 at each end. As shown in FIG. 3, the P-type thermoelectric element 11 and the N-type thermoelectric element 12 in the thermoelectric conversion module 16 are described as "electrode 13, P-type thermoelectric element 11, electrode 13, N-type thermoelectric element 12, electrode 13, ... It may be arranged as "...", and may be arranged as "electrode 13, P-type thermoelectric element 11, N-type thermoelectric element 12, electrode 13, P-type thermoelectric element 11, N-type thermoelectric element 12, electrode 13, ...". It may be arranged as "...", and further, as "electrode 13, P-type thermoelectric element 11, N-type thermoelectric element 12, P-type thermoelectric element 11, N-type thermoelectric element 12, ... electrode 13". It may be placed in.
Further, the thermoelectric conversion module may be formed directly on the high thermal conductive portion and the low thermal conductive portion, or may be formed via other layers, but it is said that a temperature difference can be efficiently applied to the thermoelectric element. From the point of view, it is preferable that the thermoelectric conversion module is formed directly on the high thermal conductive portion and the low thermal conductive portion.
The thermoelectric element is not particularly limited, but in the temperature range of the heat source converted into electric energy by the thermoelectric conversion module, the absolute value of the Seebeck coefficient is large, the thermal conductivity is low, and the electric conductivity is high, so-called thermoelectric performance. It is preferable to use a material with a high index.

The materials constituting the P-type thermoelectric element and the N-type thermoelectric element are not particularly limited as long as they have thermoelectric conversion characteristics, but bismuth-tellude-based thermoelectric semiconductor materials such as bismuth sterlide and Bi ₂ Te ₃ , GeTe, Telluride thermoelectric semiconductor materials such as PbTe, antimony-tellu thermoelectric semiconductor materials, zinc-antimon thermoelectric semiconductor materials such as ZnSb, Zn ₃ Sb ₂ , Zn ₄ Sb ₃ , silicon-germanium thermoelectric semiconductor materials such as SiGe, Bi. Bismuth selenide-based thermoelectric semiconductor materials such as ₂ Se ₃ , VDD-based thermoelectric semiconductor materials such as β-FeSi ₂ , CrSi ₂ , MnSi _1.73 , Mg ₂ Si, oxide-based thermoelectric semiconductor materials, FeVAL, FeVALSi, FeVTiAl, etc. Bismuth material is used.
The thickness of the P-type thermoelectric element 11 and the N-type thermoelectric element 12 is preferably 0.1 to 100 μm, more preferably 1 to 50 μm.
The thicknesses of the P-type thermoelectric element 11 and the N-type thermoelectric element 12 are not particularly limited, and may be the same thickness or different thicknesses.

[Manufacturing method of thermally conductive adhesive sheet]
The method for producing a heat conductive adhesive sheet of the present invention is composed of a high heat conductive part and a low heat conductive part, and the high heat conductive part and the low heat conductive part independently constitute all the thicknesses of the heat conductive adhesive sheet. , Or either of them is a method for producing a heat conductive adhesive sheet which constitutes a part of the thickness of the heat conductive adhesive sheet, and is a high thermal conductive portion formed from the adhesive resin composition on the release sheet. It is characterized by including a step of forming a low thermal conductive portion formed from the adhesive resin composition.

<High thermal conductivity part forming process>
This is a step of forming a high thermal conductive portion. The high thermal conductive portion is formed on the release sheet, or on the release sheet and on the low thermal conductive portion by using the adhesive resin composition containing the adhesive resin and the heat conductive filler and / or the conductive carbon compound. The method for applying the adhesive resin composition is not particularly limited, and for example, the adhesive resin composition may be formed by a known method such as a stencil printing method, a dispenser, a screen printing method, a roll coating method, or a slot die.
In the adhesive resin composition used in the present invention, the curing conditions when a thermosetting adhesive resin is used are appropriately adjusted depending on the composition used, but are preferably 80 ° C. to 150 ° C., more preferably. It is 90 ° C to 120 ° C. Further, if necessary, curing can be performed while pressurizing.
When an energy ray-curable adhesive resin is used, examples of the energy radiation include ultraviolet rays, electron beams, X-rays, radiation, visible rays, and the like. Among these, ultraviolet rays are preferably used, and as the light source, for example, a low pressure mercury lamp, a medium pressure mercury lamp, a high pressure mercury lamp, an ultrahigh pressure mercury lamp, a carbon arc lamp, a metal halide lamp, a xenon lamp and the like can be used. The amount of light is usually 100 to 1500 mJ / cm ² . When an electron beam is used, an electron beam accelerator or the like is used, and the irradiation amount is usually 150 to 350 kV. When ultraviolet rays are used, it is necessary to add the above-mentioned photopolymerization initiator to the adhesive resin composition. Further, when an electron beam is used, a cured film can be obtained without adding a photopolymerization initiator.

<Low thermal conductivity part forming process>
This is a step of forming a low thermal conductive portion. The low heat conductive portion is formed on the release sheet, or on the release sheet and on the high heat conductive portion in the same manner as the formation of the high heat conductive portion by using the adhesive resin composition containing the adhesive resin and the hollow filler. To. The method for applying the adhesive resin composition is not particularly limited, and is formed by a known method such as a stencil printing method, a dispenser, a screen printing method, a roll coating method, or a slot die, as in the case of a high thermal conductive portion. do it. Further, the curing method is the same as the curing method of the high thermal conductive portion.
The order of formation of the high thermal conductive portion and the low thermal conductive portion is not particularly limited. It may be appropriately selected according to the specifications of the electronic device.

According to the manufacturing method of the present invention, heat is released or the flow of heat can be controlled in a specific direction inside an electronic device or the like by a simple method, and heat conductive adhesion having high dimensional accuracy in which curing shrinkage is suppressed. Sheets can be manufactured.

Next, the present invention will be described in more detail with reference to Examples, but the present invention is not limited to these examples.

The curing shrinkage rate, thermal conductivity measurement, temperature difference evaluation, and electronic device evaluation of the heat conductive sheets produced in Examples and Comparative Examples were carried out by the following methods.
(A) Measurement of Composite Curing Shrinkage Rate of Thermally Conductive Adhesive Sheet The composite curing shrinkage rate is a stripe pattern formed from an adhesive resin composition for forming a high thermal conductive portion and an adhesive resin for forming a low thermal conductive portion with a release sheet. A group of stripe patterns (100 mm × 100 mm, thickness 100 μm; however, the composition of the thickness of the heat conductive adhesive sheet is different, and the stripe pattern is a high heat conductive part or a low heat conductive part, which is a composite of the strip pattern formed from the composition. Digital multimeter for the dimensional change before and after curing (curing condition: it depends on the resin composition used, but it shall be performed under the optimum curing condition) of the entire width in the pitch direction (including the case where only one of the above is used). It was measured by (NRM-S3-XY type manufactured by Nippon Kogaku Co., Ltd.) and calculated from the following formula.
Composite curing shrinkage rate (%) = [(total width in stripe pattern pitch direction before curing-total width in stripe pattern pitch direction after curing) / total width in stripe pattern pitch direction before curing] x 100
The specifications of the stripe pattern are as described above, and the dimension measurement after curing is performed without the release sheet, that is, the stress relaxation after curing is removed in order to prevent the release sheet from suppressing the shrinkage of the cured product. This was applied to a cured product that had been peeled off from the sheet (however, the cured product was allowed to stand on a flat surface such as a glass substrate on which stress relaxation was not hindered).

(B) Thermal Conductivity Measurement of Thermal Conductivity Adhesive Sheet The thermal conductivity was measured using a thermal conductivity measuring device (HC-110, manufactured by EKO).

(C) Temperature measurement of high thermal conductive part and low thermal conductive part As shown in FIG. 5, the obtained heat conductive adhesive sheet is an adherend made of soda glass (size 50 mm × 50 mm, thickness 0.5 mm). After sticking to the upper surface of No. 2, the release sheet was peeled off. Next, the lower surface of the adherend 2 was heated at 75 ° C. for 1 hour to stabilize the temperature, and then the temperature of the adherend was measured by a K thermocouple (chromel alumel) attached to the upper surface of the adherend 2. The thermocouple is provided on the adherend of the portion corresponding to the high thermal conduction portion and the low thermal conduction portion (measurement location: temperature difference measurement unit 6; A, B, C, D in FIG. 5). The temperature of the thermocouple was measured every second for 5 minutes, and the average value at each of the obtained points was calculated.

(Manufacturing of thermoelectric conversion module)
As shown in a part of FIG. 6, a P-type thermoelectric element 21 (P-type bismuth-tellu-based thermoelectric semiconductor material) and an N-type thermoelectric element 22 (N-type bismuth-tellu-based thermoelectric semiconductor material) are placed on the support 26. ) Are arranged so as to have the same size (width 1.7 mm × length 100 mm, thickness 0.5 mm), and a copper electrode (copper electrode 23a: width 0.) is placed between both thermoelectric elements and the thermoelectric element. 15 mm × length 100 mm, thickness 0.5 mm; copper electrode 23b: width 0.3 mm × length 100 mm, thickness 0.5 mm; copper electrode 23c: width 0.15 mm × length 100 mm, thickness 0.5 mm) A thermoelectric conversion module 27 was manufactured.

(Electronic device evaluation)
The lower surface 28 (see FIG. 6) of the thermoelectric conversion device obtained in Examples and Comparative Examples was heated to 75 ° C. on a hot plate, and the upper surface 29 (see FIG. 6) on the opposite side was cooled to 25 ° C. After holding for 1 hour and stabilizing the temperature, the thermoelectromotive force V (V) and the electric resistance R (Ω) were measured. The output P (W) was calculated by P = V ² / R using the measured thermoelectromotive force V and electric resistance R.

(Example 1)
(1) Preparation of thermally conductive adhesive sheet Silicone resin A (manufactured by Asahi Kasei Wacker, "SilGel612-A") 19.8 parts by mass, silicone resin B (manufactured by Asahi Kasei Wacker, "SilGel612-B") 19.8 parts by mass Parts, 0.4 parts by mass of curing retardant (manufactured by Asahi Kasei Wacker Co., Ltd., "PT88"), 40 parts by mass of alumina (manufactured by Showa Denko Co., Ltd., "Arna beads CB-A20S", average particle diameter 20 μm) Add 20 parts by mass of boron nitride ("Show BN UHP-2" manufactured by Showa Denko Co., Ltd., average particle diameter 12 μm), and mix and disperse using a rotation / revolution mixer (manufactured by THINKY, "ARE-250"). , An adhesive resin composition for forming a high thermal conductive portion was prepared.
On the other hand, silicone resin A (manufactured by Asahi Kasei Wacker, "SilGel612-A") 31.7 parts by mass, silicone resin B (manufactured by Asahi Kasei Wacker, "SilGel612-B") 31.7 parts by mass, curing retarder (Asahi Kasei Wacker) 0.6 parts by mass of "PT88" manufactured by Sumitomo, 36 parts by mass of hollow glass filler ("Glass Bubbles S38" manufactured by Sumitomo 3M, average particle diameter 40 μm, true density 0.38 g / cm ³ ) (60% by mass of hollow glass filler is contained in the entire volume of the low heat conductive part), mixed and dispersed using a rotation / revolution mixer (manufactured by THINKY, "ARE-250"), and adhered for forming the low heat conductive part. A sex resin composition was prepared.
Next, the adhesive resin composition for forming the high thermal conductive portion is applied to the peeled surface of the peeling sheet (Lintec Corporation, "PET50FD") with a dispenser (Musashi Engineering Co., Ltd., "ML-808FXcom-CE"). ) Was applied to form a high thermal conductive portion 24 (see FIG. 6) composed of a striped pattern (width 1 mm × length 100 mm, thickness 50 μm, distance between pattern centers 2 mm). Further, an adhesive resin composition for forming a low thermal conductive portion is applied from above using an applicator, dried at 150 ° C. for 5 minutes, and then heated at 150 ° C. for 30 minutes to cure the thermally conductive adhesive sheet. A heat conductive adhesive sheet was obtained in which a low heat conductive portion 25 (see FIG. 6) having the same thickness as the high heat conductive portion was formed between the striped patterns of the high heat conductive portion. It was confirmed that the low thermal conductive portion was not formed on the high thermal conductive portion.

(2) Preparation of Thermoelectric Conversion Device Two obtained heat conductive adhesive sheets were prepared, and as shown in FIG. 6, the heat conductive adhesive sheet was attached to the surface of the thermoelectric conversion module 27 on the side where the thermoelectric element was formed. A thermoelectric conversion device was prepared by laminating each on the surface on the support side and laminating a heat conductive adhesive sheet on both sides.
The storage elastic modulus of the high thermal conductive portion 24 at 150 ° C. after curing was 2.3 MPa, and the storage elastic modulus of the low thermal conductive portion 25 after curing at 150 ° C. was 1.6 MPa. The volume resistivity of the high thermal conductivity portion 24 was 7.2 × 10 ¹⁴ Ω · cm, and the volume resistivity of the low thermal conductive portion 25 was 2.4 × 10 ¹⁵ Ω · cm.

(Example 2)
42.6 parts by mass of silicone resin A (manufactured by Asahi Kasei Wacker, "SilGel612-A") and silicone resin B (manufactured by Asahi Kasei Wacker, "SilGel612-B") 42. 6 parts by mass, curing retardant (manufactured by Asahi Kasei Wacker, "PT88") 0.8 parts by mass, as a hollow filler, glass hollow filler (manufactured by Sumitomo 3M, "Glass Bubbles S38", average particle diameter 40 μm, true density 0.38 g / cm ³ ) The heat conductive adhesive sheet and the thermoelectric conversion device were used in the same manner as in Example 1 except that 14 parts by mass (30% by mass of hollow glass filler was contained in the total volume of the low heat conductive part). Made.
The storage elastic modulus at 150 ° C. after curing of the high thermal conductive portion was 2.3 MPa, and the storage elastic modulus at 150 ° C. after curing of the low thermal conductive portion was 0.2 MPa. The volume resistivity of the high thermal conductivity part was 7.2 × 10 ¹⁴ Ω · cm, and the volume resistivity of the low thermal conductive part was 2.4 × 10 ¹⁵ Ω · cm.

(Example 3)
Using the adhesive resin composition for forming the high thermal conductive portion used in Example 1, a striped pattern (width 1 mm × length 100 mm, thickness) was applied to the peeled surface of the peeling sheet in the same manner as in Example 1. A high thermal conductive portion having a size of 50 μm and a distance between pattern centers of 2 mm) was formed.
Next, the adhesive resin composition for forming the low thermal conductive portion used in Example 1 was applied thereto, dried at 150 ° C. for 5 minutes, and then heated at 150 ° C. for 30 minutes to cure the thermally conductive adhesive sheet. , A low thermal conductive portion having a thickness of 75 μm was formed to prepare a thermally conductive adhesive sheet. A low thermal conductive portion was formed between the striped patterns of the high thermal conductive portion and on the high thermal conductive portion, and a low thermal conductive portion having a thickness of 25 μm was formed on the high thermal conductive layer portion. Two obtained thermally conductive adhesive sheets were prepared, and in the same manner as in Example 1, the lower surface of FIG. 2C was formed on the surface of the thermoelectric conversion module 27 on the side where the thermoelectric element was formed and the surface on the support side. A thermoelectric conversion device in which a heat conductive adhesive sheet was laminated on both sides was produced by laminating the sides, such as the side, which are composed of only low heat conductive parts by sticking them to each.

(Example 4)
Two heat conductive adhesive sheets obtained in Example 3 were prepared, and the heat conductive adhesive sheets were placed on the surface of the thermoelectric conversion module 27 on the side where the thermoelectric element was formed and the surface on the support side, FIG. 2 (c). A thermoelectric conversion device in which a heat conductive adhesive sheet was laminated on both sides was produced by laminating the side surface composed of a high thermal conductive portion and a low thermal conductive portion, respectively, as on the upper surface side of the above.

(Example 5)
Example 1 except that hollow nanosilica (manufactured by Nittetsu Mining Co., Ltd., "Sirinax" (registered trademark), average particle diameter 105 nm, true density 0.57 g / cm ³ ) was used as the hollow filler. A thermoelectric conversion device was produced in the same manner as in the above.

(Comparative Example 1)
A heat conductive adhesive sheet and a thermoelectric conversion device using the same were produced in the same manner as in Example 1 except that the hollow glass filler was not added to the low heat conductive part.
The storage elastic modulus at 150 ° C. after curing of the high thermal conductive portion was 2.3 MPa, and the storage elastic modulus at 150 ° C. after curing of the low thermal conductive portion was 0.2 MPa. The volume resistivity of the high thermal conductivity part was 7.2 × 10 ¹⁴ Ω · cm, and the volume resistivity of the low thermal conductive part was 2.6 × 10 ¹⁵ Ω · cm.

(Comparative Example 2)
An adhesively processed PGS graphite sheet (manufactured by Panasonic Corporation, product number: EYGA091201M, PGS graphite sheet thickness: 10 μm, adhesive thickness 10 μm, thermal conductivity: 1950 (W / m · K)) was used as a heat conductive adhesive sheet.
Two heat conductive adhesive sheets are prepared, and the heat conductive adhesive sheets are laminated on the surface of the thermoelectric conversion module 27 on the side where the thermoelectric element is formed and the surface on the support side, respectively, and the heat conductive adhesive sheets are laminated on both sides. The thermoelectric conversion device was manufactured.

(Comparative Example 3)
The temperature difference was measured without attaching the heat conductive adhesive sheet to the adherend. Further, the electronic device was evaluated without laminating the heat conductive adhesive sheet on the thermoelectric conversion module 27.

Table 1 shows the evaluation results of the composite curing shrinkage rate, thermal conductivity, temperature difference and / or electron (thermoelectric conversion) device of the heat conductive adhesive sheets and the like obtained in Examples 1 to 5 and Comparative Examples 1 to 3. .. The result of the electronic device evaluation of Comparative Example 1 was 0 because the positional deviation between the heat conductive adhesive sheet and the thermoelectric conversion element was large (derived from composite curing shrinkage), which is suitable for the thermoelectric conversion element. It is probable that the temperature difference could not be given to.

In the heat conductive adhesive sheet of the present invention used in Examples 1, 2 and 5, the composite curing shrinkage rate is suppressed and the dimensions are smaller than those of Comparative Example 1 which has the same sheet structure and does not contain a hollow filler in the low heat conductive portion. It was found that the accuracy was improved and the thermal conductivity was lowered. It was also found that a large temperature difference between the high heat conductive part and the adjacent low heat conductive part can be obtained. Furthermore, high output was obtained in the evaluation of electronic devices.

When the heat conductive adhesive sheet of the present invention is applied to a thermoelectric conversion module of a thermoelectric conversion device, which is one of electronic devices, it can be attached to a thermoelectric element or the like with high dimensional accuracy, and has a thermal conductivity with a high thermal conductivity portion. Since the difference can be made larger, the temperature difference can be efficiently applied in the thickness direction of the thermoelectric element. Therefore, power generation with high power generation efficiency becomes possible, the number of thermoelectric conversion modules installed can be reduced as compared with the conventional type, which leads to downsizing and cost reduction. At the same time, by using the heat conductive adhesive sheet of the present invention, it can be used as a flexible thermoelectric conversion device without any limitation on the installation location such as installation on a waste heat source or a heat radiation source having an uneven surface. ..

1,1A, 1B: Thermal conductive adhesive sheet 2: Adhesive body 4, 4a, 4b: High thermal conductivity section 5, 5a, 5b: Low thermal conductivity section 6: Temperature difference measurement section 10: Thermoelectric conversion device 11: P-type thermoelectric Element 12: N-type thermoelectric element 13: Electrode (copper)
14a, 14b :: High thermal conductivity section 14'a, 14'b, 14'c: High thermal conductivity section 15a, 15b, 15c: Low thermal conductivity section 15'a, 15'b: Low thermal conductivity section 16: Thermoelectric conversion module 17: 16 first surface 18:16 second surface 19: support 20: thermoelectric conversion device 21: P-type thermoelectric element 22: N-type thermoelectric element 23a, 23b, 23c: electrode (copper)
24: High thermal conductive portion 25: Low thermal conductive portion 26: Support 27: Lower surface of thermoelectric conversion module 28:27 29: 27 Upper surface 41: P-type thermoelectric element 42: N-type thermoelectric element 43: Electrode (copper)
44: Film-like substrate 45: Film-like substrate 46: Thermoelectric conversion modules 47, 48: Material with low thermal conductivity (polyimide)
49,50: Material with high thermal conductivity (copper)
51, 52: Low thermal conductivity member 53: Thermoelectric element 54: Electrode (copper)
55: Conductive adhesive layer 56: Insulating adhesive layer 61: Thermoelectric element 62: Flexible substrate 63: Metal layer (copper)
64: Resin layer 65: Insulating base layer layer 66: Flexible substrate 67: Adhesive layer

Claims (13)

A thermally conductive adhesive sheet having a high thermal conductive portion and a low thermal conductive portion, wherein the high thermal conductive portion and the low thermal conductive portion have adhesiveness, and a hollow filler is provided on the low thermal conductive portion in the low thermal conductive portion. It contained 20 to 90 vol% in a total volume,
And the high thermal conductivity portion and the low thermal conductive portion is present in the surface direction of the heat conductive adhesive sheet, and independently and thicknesses of the low thermal conductive portion of the high thermal conductive portion of the thermally-conductive adhesive sheet thickness It has the same composition ,
Both of the high thermal conductivity portion and the low thermal conductive portion is present on one surface of the heat conductive adhesive sheet, its either these at least is the same configuration as the thickness direction of the thickness of the thermally conductive adhesive sheet ,
Or
The separated high heat conductive part or the separated low heat, in which either the high heat conductive part or the low heat conductive part is present on one surface of the heat conductive adhesive sheet and the other surface is not present on the one surface. It is composed of either of the conductive portions, and the sum of them in the thickness direction has the same configuration as the thickness in the thickness direction of the heat conductive adhesive sheet.
Thermally conductive adhesive sheet. The heat conductive adhesive sheet according to claim 1, wherein the high thermal conductive portion and the low thermal conductive portion are formed from an adhesive resin composition. The heat conductive adhesive sheet according to claim 2, wherein the adhesive resin composition contains at least one of a thermosetting resin and an energy ray curable resin. The heat conductive adhesive sheet according to claim 3, wherein the thermosetting resin is a silicone resin or a urethane resin. The heat conductive adhesive sheet according to claim 2, wherein the adhesive resin composition of the high heat conductive portion contains a heat conductive filler and / or a conductive carbon compound. The heat conductive adhesive sheet according to claim 5, wherein the heat conductive filler contains at least one selected from the group consisting of metal oxides, metal nitrides, and metals. The heat conductive adhesive sheet according to claim 1, wherein the hollow filler is a glass hollow filler or a silica hollow filler. The heat conductive adhesive sheet according to claim 7, wherein the true density of the hollow glass filler and the hollow silica filler is 0.1 to 0.6 g / cm ³ . The heat conductive adhesive sheet according to any one of claims 2 to 6, wherein the composite curing shrinkage rate of the adhesive resin composition of the high heat conductive portion and the low heat conductive portion is 2% or less. The thermal conductivity of the high thermal conductivity portion of the thermally conductive adhesive sheet is 0.5 (W / m · K) or more, and the thermal conductivity of the low thermal conductivity portion is less than 0.5 (W / m · K). The heat conductive adhesive sheet according to any one of claims 1 to 9. A thermoelectric conversion module using the heat conductive adhesive sheet according to any one of claims 1 to 10. An electronic device using the heat conductive adhesive sheet according to any one of claims 1 to 10. The method for producing a heat conductive adhesive sheet according to any one of claims 1 to 10, wherein a high heat conductive portion formed from the adhesive resin composition and an adhesive resin composition are used on the release sheet. A method for producing a thermosetting adhesive sheet, which comprises a step of forming a low thermal conductive portion to be formed.

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