Thermoelectric conversion module

Abstract

To provide a thermoelectric conversion module that is equipped with a release sheet that does not inhibit thermoelectric performance, functions as a support substrate during the manufacturing process, and is suppressed from deformation and damage during transportation and handling.SOLUTION: A thermoelectric conversion module includes a thermoelectric element layer in which P-type thermoelectric elements and N-type thermoelectric elements are arranged alternately and electrically connected in series, a first conductive layer provided on a first surface of the thermoelectric element layer, a first adhesive layer provided on a surface of the first conductive layer opposite to the surface on the thermoelectric element layer side, and a first release sheet provided on a surface of the first adhesive layer opposite to the surface on the first conductive layer side, and the curvature of the first release sheet is R1000 or more when the first release sheet is cut to a length of 250 mm and hung at the center in the longitudinal direction.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present invention relates to a thermoelectric conversion module. [Background technology]

[0002] 2. Description of the Related Art Conventionally, as one of the means for effectively utilizing energy, there has been a device that directly converts thermal energy into electrical energy and vice versa using a thermoelectric conversion module that has a thermoelectric effect such as the Seebeck effect or the Peltier effect.

[0003] As the thermoelectric conversion module, the use of a so-called π-type thermoelectric conversion element is known. A π-type thermoelectric conversion element has a pair of electrodes spaced apart on a substrate, with the underside of a P-type thermoelectric element on one electrode and the underside of an N-type thermoelectric element on the other electrode, also spaced apart, as its basic unit, and the top surfaces of both types of thermoelectric elements connected to electrodes on the opposing substrates.Typically, multiple such basic units are configured within both substrates, connected electrically in series and thermally in parallel. In recent years, in order to fully commercialize products and the like using thermoelectric conversion modules including such π-type thermoelectric conversion elements, there have been various demands, such as thinner thermoelectric conversion modules, further improved thermoelectric performance, and improved reliability including weather resistance and impact resistance. For example, Patent Document 1 discloses a thermoelectric conversion module using the above-mentioned π-type thermoelectric conversion elements. In the thermoelectric conversion module of Patent Document 1, the π-type thermoelectric conversion elements are integrated into one body by filling the gaps between the alternately spaced chips of P-type thermoelectric conversion material and N-type thermoelectric conversion material chips with an insulator, thereby eliminating the need for a support substrate with high thermal resistance as a conventional support. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2022 / 092177 Summary of the Invention [Problem to be solved by the invention]

[0005] However, since Patent Document 1 does not have a supporting substrate, there is a concern that the mechanical strength will be reduced, resulting in deformation and damage during transportation and handling.

[0006] The present invention has been made in consideration of the above-described circumstances, and has an object to provide a thermoelectric conversion module equipped with a release sheet that does not suppress thermoelectric performance, functions as a support substrate during the manufacturing process, and is suppressed from deformation and damage during transportation and handling. [Means for solving the problem]

[0007] As a result of extensive research into solving the above problems, the inventors discovered that by configuring the thermoelectric conversion element in a thermoelectric conversion module to include a first conductive layer provided on a first surface of the thermoelectric element layer, a first adhesive layer provided on the side of the first conductive layer opposite the side facing the thermoelectric element layer, and a first release sheet provided on the side of the first adhesive layer opposite the side facing the first conductive layer, and by setting the curvature of the first release sheet to a specific value, the first release sheet functions as a supporting substrate during the manufacturing process, and deformation and damage during transportation and handling are suppressed, thereby completing the present invention. That is, the present invention provides the following [1] to [8]. [1] A thermoelectric conversion module comprising: a thermoelectric element layer in which P-type thermoelectric elements and N-type thermoelectric elements are arranged alternately and electrically connected in series; a first conductive layer provided on a first surface of the thermoelectric element layer; a first adhesive layer provided on a surface of the first conductive layer opposite to the surface on the thermoelectric element layer side; and a first release sheet provided on a surface of the first adhesive layer opposite to the surface on the first conductive layer side, wherein the curvature of the first release sheet is R1000 or more when the first release sheet is cut to a length of 250 mm and hung at the center in the longitudinal direction. [2] The thermoelectric conversion module according to [1] above, further comprising a second conductive layer provided on a second surface opposite to the first surface of the thermoelectric element layer. [3] The thermoelectric conversion module according to [2] above, further comprising a second adhesive layer provided on the surface of the second conductive layer opposite to the surface on the thermoelectric element layer side. [4] The thermoelectric conversion module according to [3] above, which has a second release sheet provided on the surface of the second adhesive layer opposite to the surface on the second conductive layer side. [5] The thermoelectric conversion module according to [4] above, wherein the peel strength of the first release sheet is greater than or smaller than the peel strength of the second release sheet. [6] The thermoelectric conversion module according to any one of [1] to [5] above, wherein the first adhesive layer is a patterned layer made of an adhesive composition, and the surface of the first conductive layer is in contact with a surface of the patterned layer having the same shape as the surface of the first conductive layer. [7] A thermoelectric conversion module according to any one of [1] to [5] above, wherein the first adhesive layer is a solid layer made of an adhesive composition, and the surface of the first conductive layer is in contact with the surface of a partial area of ​​the solid layer. [8] The thermoelectric conversion module according to any one of the above [1] to [7], which includes a gap formed by a region between the P-type thermoelectric element layer and the N-type thermoelectric element layer. [Effects of the Invention]

[0008] According to the present invention, it is possible to provide a thermoelectric conversion module equipped with a release sheet that does not suppress thermoelectric performance, functions as a support substrate during the manufacturing process, and is suppressed from deformation and damage during transportation and handling. [Brief explanation of the drawings]

[0009] [Figure 1] FIG. 1 is a cross-sectional view showing an embodiment (configuration A) of a thermoelectric conversion module of the present invention. [Figure 2] FIG. 4 is a cross-sectional view showing another embodiment (configuration C) of the thermoelectric conversion module of the present invention. DETAILED DESCRIPTION OF THE INVENTION

[0010] [Thermoelectric conversion module] The thermoelectric conversion module of the present invention comprises a thermoelectric element layer in which P-type thermoelectric elements and N-type thermoelectric elements are arranged alternately and electrically connected in series, a first conductive layer provided on a first surface of the thermoelectric element layer, a first adhesive layer provided on a surface of the first conductive layer opposite to the surface on the thermoelectric element layer side, and a first release sheet provided on a surface of the first adhesive layer opposite to the surface on the first conductive layer side, wherein the curvature of the first release sheet is R1000 or more when the first release sheet is cut to a length of 250 mm and hung at the center in the longitudinal direction. The thermoelectric conversion module of the present invention includes a first conductive layer provided on a first surface of the thermoelectric element layer, a first adhesive layer provided on the surface of the first conductive layer opposite the surface facing the thermoelectric element layer, and a first release sheet provided on the surface of the first adhesive layer opposite the surface facing the first conductive layer. Furthermore, by setting the curvature of the first release sheet to a specific value, the first release sheet functions as a support substrate during the manufacturing process, thereby preventing deformation and damage during transportation and handling. Furthermore, after the first release sheet is peeled off, the support substrate is peeled off, allowing the thermoelectric conversion module to be made thinner.

[0011] In this specification, preferred definitions can be selected arbitrarily, and combinations of preferred definitions can be considered more preferred. In this specification, the expression "XX to YY" means "XX or more and YY or less." In this specification, for preferred numerical ranges (e.g., ranges of content, etc.), the lower and upper limits described in stages can be independently combined. For example, the description "preferably 10 to 90, more preferably 30 to 60" can be combined with the "preferable lower limit (10)" and the "more preferable upper limit (60)" to form "10 to 60."

[0012] In this specification, the term "solid layer" means "a layer having a surface that extends continuously without interruption in thickness in a direction perpendicular to the thickness direction of the layer."

[0013] The thermoelectric conversion module of the present invention includes a thermoelectric element layer in which P-type thermoelectric elements and N-type thermoelectric elements are alternately arranged and electrically connected in series, a first conductive layer provided on a first surface of the thermoelectric element layer, a first adhesive layer formed as a solid layer provided on the surface of the first conductive layer opposite to the surface facing the thermoelectric element layer, and a first release sheet provided on the surface of the first adhesive layer opposite to the surface facing the first conductive layer. The curvature of the first release sheet is R1000 or greater when the first release sheet is cut to a length of 250 mm and hung at the center in the longitudinal direction.

[0014] In one embodiment of the present invention, it is preferable to have a second conductive layer provided on a second surface opposite to the first surface of the thermoelectric element layer. It is also preferable that the second conductive layer has a second adhesive layer provided on the surface opposite to the surface on the thermoelectric element layer side. Furthermore, it is preferable that the second pressure-sensitive adhesive layer has a second release sheet provided on the surface opposite to the surface on the second conductive layer side.

[0015] In one embodiment, the first pressure-sensitive adhesive layer is a solid layer made of a pressure-sensitive adhesive composition, and it is preferable that the surface of the solid layer is in contact with the surface of the first conductive layer at a partial area thereof.

[0016] In one embodiment of the present invention, a gap formed by a region between the P-type thermoelectric element layer and the N-type thermoelectric element layer may be included. By including the gap, the thermal resistance can be set high, and the thermoelectric performance of the thermoelectric conversion module can be maintained at a high level. In another embodiment, the gap between the P-type thermoelectric element layer and the N-type thermoelectric element layer may not be included. That is, the gap may be filled with the adhesive of the first or second adhesive layer. In this case, the strength of the thermoelectric conversion module can be improved.

[0017] When the ratio V of voids in a vertical cross section consisting of the region between the P-type thermoelectric element and the N-type thermoelectric element is defined by the following formula, the ratio V of voids is 0 to 1.0, preferably more than 0 and 1.0 or less, more preferably 0.5 to 1.0, and particularly preferably 0.8 to 1.0. V = 1 - [(maximum filling distance from the surface of the first conductive layer opposite the surface on the thermoelectric element layer side to the thickness direction of the thermoelectric element layer of the first adhesive layer) / (thickness of the first conductive layer + thickness of the thermoelectric element layer)]

[0018] FIG. 1 is a cross-sectional view showing an embodiment (structure A) of the thermoelectric conversion module of the present invention. The thermoelectric conversion module 1 includes a thermoelectric element layer 2 in which P-type thermoelectric elements 2p and N-type thermoelectric elements 2n are alternately arranged and electrically connected in series, a first conductive layer 4b provided on a first surface 2b of the thermoelectric element layer 2, a first adhesive layer 3b formed as a solid layer provided on the surface of the first conductive layer 4b opposite to the surface facing the thermoelectric element layer 2, a first release sheet 5b provided on the surface of the first adhesive layer 3b opposite to the surface facing the first conductive layer 4b, a second conductive layer 4a provided on a second surface 2a of the thermoelectric element layer 2 facing the first surface 2b of the thermoelectric element layer 2, a second adhesive layer 3a formed as a solid layer provided on the surface of the second conductive layer 4a opposite to the surface facing the thermoelectric element layer 2, and a second release sheet 5a provided on the surface of the second adhesive layer 3a opposite to the surface facing the second conductive layer 4a. Here, the curvature of first release sheet 5b is R1000 or more when first release sheet 5b is cut into a length of 250 mm and hung at the center in the longitudinal direction.

[0019] In another embodiment, the first pressure-sensitive adhesive layer is a patterned layer made of a pressure-sensitive adhesive composition, and the surface of the first conductive layer is preferably in contact with a surface of a patterned layer having the same shape as the surface of the first conductive layer. When the first pressure-sensitive adhesive layer is a patterned layer having the same shape as the surface of the first conductive layer, for example, it is possible to prevent short circuits between adjacent first conductive layers and a decrease in thermoelectric performance. Furthermore, for example, the patterned layer can contain particles with high thermal conductivity, which leads to reduced thermal resistance.

[0020] FIG. 2 is a cross-sectional view showing another embodiment (configuration C) of the thermoelectric conversion module of the present invention. The thermoelectric conversion module 11 includes a thermoelectric element layer 12 in which P-type thermoelectric elements 12p and N-type thermoelectric elements 12n are alternately arranged so as to be electrically connected in series, a first conductive layer 14b provided on a first surface 12b of the thermoelectric element layer 12, a first adhesive layer 13b provided on the surface of the first conductive layer 14b opposite to the surface on the thermoelectric element layer 12 side and in contact with the surface of a pattern layer having the same shape as the first conductive layer 14b, and a first adhesive layer 13b on the first adhesive layer 13b. The thermoelectric element 10 has a first release sheet 15b provided on the surface opposite to the surface on the conductive layer 14b side, a second conductive layer 14a provided on a second surface 12a of the thermoelectric element layer 12 facing the first surface 12b of the thermoelectric element layer 12, a second adhesive layer 13a formed as a solid layer provided on the surface of the second conductive layer 14a opposite to the surface on the thermoelectric element layer 12 side, and a second release sheet 15a provided on the surface of the second adhesive layer 13a opposite to the surface on the second conductive layer 14a side. Here, the curvature of the first release sheet 15b is R1000 or more when the first release sheet 15b is cut to a length of 250 mm and hung at the center in the longitudinal direction. As another embodiment of Figure 2, the second adhesive layer may also be a patterned layer having the same shape as the second conductive layer 14a, and the thermoelectric conversion module may be formed by stacking the second adhesive layer and the second conductive layer 14a so that the patterns match.

[0021] The curvature of the first release sheet is R1000 or more when the first release sheet is cut to a length of 250 mm and hung at the center in the longitudinal direction. Here, R is the radius, and 1000 has a unit of mm, meaning that a 250 mm long first release sheet describes an arc with a radius of 1 m. Furthermore, the larger the value of R, the more gentle the arc. R is preferably 1050 mm or more, more preferably 1100 mm or more, and even more preferably 1200 mm to 2000 mm. When the R of the first release sheet is within this range, ease of handling during the manufacturing process can be ensured.

[0022] Preferably, the release strength of the first release sheet is different from that of the second release sheet, and the release strength of the first release sheet is greater than or less than that of the second release sheet. Having a difference in release strength between the first and second release sheets allows the release sheet with the smaller release strength to be selectively peeled off, thereby reducing damage to the thermoelectric conversion module during peeling. Furthermore, when the release strength of the first release sheet is greater than that of the second release sheet, for example, handling is more easily ensured from the time when the second release sheet of the thermoelectric conversion module of the present invention is peeled off and the second pressure-sensitive adhesive layer is attached to an adherend, until the first release sheet of the thermoelectric conversion module is peeled off and the first pressure-sensitive adhesive layer is attached to another adherend. On the other hand, if the release force of the first release sheet is smaller than that of the second release sheet, it is easier to select a second release sheet with a smaller curvature, making it easier to store a long thermoelectric conversion module in a roll.

[0023] The first and second release sheets preferably comprise a release substrate and a release agent layer formed by applying a release agent to the release substrate. The release sheet may comprise a release agent layer on only one side of the release substrate, or on both sides of the release substrate. Examples of release substrates include paper substrates, laminated paper obtained by laminating a thermoplastic resin such as polyethylene to the paper substrate, and plastic films. Examples of paper substrates include glassine paper, coated paper, and cast-coated paper. Examples of plastic films include polyester films such as polyethylene terephthalate, polybutylene terephthalate, and polyethylene naphthalate, and polyolefin films such as polypropylene and polyethylene. Examples of release agents include olefin-based resins, rubber-based elastomers (e.g., butadiene-based resins, isoprene-based resins, etc.), long-chain alkyl resins, alkyd-based resins, fluorine-based resins, and silicone-based resins. The peel strength of the first release sheet and the second release sheet is usually determined by the release sheet that contacts the adhesive layer. This can be controlled by varying the composition of the release agent layer in the

[0024] The peel strength of the first release sheet is not particularly limited, but is preferably 30 to 300 mN / 25 mm, more preferably 50 to 200 mN / 25 mm, and even more preferably 80 to 150 mN / 25 mm. The thickness of the release agent layer of the first release sheet is not particularly limited, but when the release agent layer is formed by applying a solution containing a release agent, the thickness of the release agent layer is preferably 0.01 to 2.0 μm, and more preferably 0.03 to 1.0 μm. When a plastic film is used as the release substrate, the thickness of the plastic film is preferably 60 to 300 μm, more preferably 80 to 200 μm, and even more preferably 90 to 140 μm. When the thickness of the release substrate is within this range, it can function as a supporting substrate during the manufacturing process and has excellent handleability.

[0025] The peel strength of the second release sheet is not particularly limited, but is preferably 40 to 1800 mN / 25 mm, more preferably 150 to 1200 mN / 25 mm, and even more preferably 580 to 950 mN / 25 mm. The thickness of the release agent layer of the second release sheet is not particularly limited, but when the release agent layer is formed by applying a solution containing a release agent, the thickness of the release agent layer is preferably 0.01 to 2.0 μm, and more preferably 0.03 to 1.0 μm. When a plastic film is used as the release substrate, the thickness of the plastic film is preferably 10 to 100 μm, more preferably 20 to 80 μm, and particularly preferably 30 to 55 μm.

[0026] The difference in peel strength between the first release sheet and the second release sheet is preferably 10 to 1500 mN / 25 mm, more preferably 100 to 1000 mN / 25 mm, and even more preferably 500 to 800 mN / 25 mm. Within this range, both release sheets can be easily peeled off without damaging the thermoelectric conversion module. The peel strength of the first release sheet and the peel strength of the second release sheet are each measured in accordance with JIS Z0237:2009.

[0027] The adhesive layer is not particularly limited as long as it can laminate a thermoelectric element layer, but it may contain an adhesive resin, and may optionally contain adhesive additives such as a crosslinking agent, a tackifier, a polymerizable compound, and a polymerization initiator, a silane coupling agent, an antistatic agent, an antioxidant, an ultraviolet absorber, a light stabilizer, a softener, a filler, a refractive index adjuster, a colorant, etc. Examples of adhesive resins include rubber-based resins such as acrylic resins, epoxy resins, urethane resins, and polyisobutylene resins, polyester resins, olefin resins, silicone resins, and polyvinyl ether resins. Among these, from the viewpoint of satisfying the range of resistivity of the first pressure-sensitive adhesive layer described below, acrylic resins, epoxy resins, rubber resins, and olefin resins are preferred.

[0028] The resistivity of the first adhesive layer is preferably 1.0×10 12 Ω·cm or more, and more preferably 5.0×10 12 Ω·cm or more, and more preferably 1.0×10 13 When the resistivity of the first adhesive layer is in this range, the insulating properties of the first adhesive layer are ensured, and short circuits between adjacent first conductive layers can be suppressed.

[0029] The pressure-sensitive adhesive layer can be formed from a pressure-sensitive adhesive composition containing a pressure-sensitive adhesive resin by a known method, such as screen printing, spin coating, spray coating, bar coating, knife coating, roll coating, roll knife coating, blade coating, die coating, or gravure coating. Among these, examples of methods for patterning the pressure-sensitive adhesive layer include a screen printing method using a screen plate corresponding to the desired pattern shape, and a gravure coating method using a roll having a concave-convex shape corresponding to the desired pattern shape, and by applying the pressure-sensitive adhesive composition, a patterned pressure-sensitive adhesive layer can be formed.

[0030] <First Conductive Layer and Second Conductive Layer> The first conductive layer and the second conductive layer (hereinafter sometimes simply referred to as "conductive layers") used in the present invention are preferably at least one selected from the group consisting of a metal electrode layer, a metal oxide electrode layer, and a conductive resin layer. Examples of metals used for the metal electrode layer include aluminum, molybdenum, cobalt, zirconium, tin, niobium, iron, chromium, tantalum, titanium, gold, platinum, vanadium, manganese, nickel, copper, hafnium, tungsten, iridium, zinc, indium, palladium, stainless steel, neodymium, silver, and alloys thereof. Examples of metal oxides used in the metal oxide electrode layer include indium-tin oxide (ITO), indium-zinc oxide (IZO), aluminum-zinc oxide (AZO), gallium-zinc oxide (GZO), indium-gallium-zinc oxide (IGZO), niobium oxide, titanium oxide, and tin oxide, and these can be used alone or in combination. Among these, indium-tin oxide (ITO) is particularly preferred from the viewpoints of surface resistivity and heat resistance. The conductive resin layer may be a conductive paste made of a conductive composition containing conductive particles. The conductive paste may be a paste in which conductive particles such as metal particles, carbon particles, or ruthenium oxide particles are dispersed in a solvent containing a binder. As the material for the metal particles, silver, copper, gold, or the like is preferred from the viewpoint of conductivity, and silver, copper, nickel, iron, cobalt, or the like is preferred from the viewpoint of cost.

[0031] Examples of methods for forming the conductive layer include a method in which an unpatterned conductive layer is provided on the adhesive layer, and then processed into a predetermined pattern shape by known physical or chemical treatments, mainly photolithography, or a combination of these, or a method in which a conductive paste made of a conductive composition containing the conductive particles is used to directly form a pattern of the conductive layer by screen printing, inkjet printing, or the like. Methods for forming a conductive layer on which no pattern is formed include dry processes such as PVD (physical vapor deposition) methods such as vacuum deposition, sputtering, and ion plating, or CVD (chemical vapor deposition) methods such as thermal CVD and atomic layer deposition (ALD), or wet processes such as various coating methods and electrodeposition methods such as dip coating, spin coating, spray coating, gravure coating, die coating, and doctor blade methods, silver halide plating, electrolytic plating, electroless plating, and lamination of metal foil, and are selected appropriately depending on the material of the conductive layer. The conductive layer used in the present invention is required to have high electrical conductivity and high thermal conductivity in order to maintain thermoelectric performance, so it is more preferable to use an electrode formed by a plating method or a vacuum film formation method. Vacuum film formation methods such as vacuum deposition and sputtering, as well as electroplating and electroless plating, are preferred because they can easily achieve high electrical conductivity and high thermal conductivity. Depending on the dimensions and dimensional accuracy required for the formed pattern, a pattern can also be easily formed via a hard mask such as a metal mask.

[0032] The thickness of the first conductive layer and the second conductive layer is preferably 10 nm to 200 μm, more preferably 1 μm to 100 μm, and even more preferably 10 μm to 60 μm. When the thickness of the conductive layer is within the above range, the electrical conductivity is high and the resistance is low, and sufficient strength as a conductive layer is obtained.

[0033] <Thermoelectric element> The thermoelectric element used in the present invention is not particularly limited, and may be a thin film containing a thermoelectric semiconductor. From the viewpoints of flexibility, thinness, and thermoelectric performance, the thin film may be made of a thermoelectric semiconductor composition containing thermoelectric semiconductor particles, a resin, and, if desired, one or both of an ionic liquid and an inorganic ionic compound.

[0034] The thermoelectric semiconductor particles used in the thermoelectric element are preferably prepared by, for example, pulverizing a thermoelectric semiconductor material to a predetermined size using a fine grinding device or the like and then using the pulverized material as thermoelectric semiconductor particles. The particle size of the thermoelectric semiconductor particles is preferably 10 nm to 100 μm, more preferably 20 nm to 50 μm, and even more preferably 30 nm to 30 μm. The average particle size of the thermoelectric semiconductor particles was obtained by measurement using a laser diffraction particle size analyzer (Malvern, Mastersizer 3000) and was taken as the median value of the particle size distribution.

[0035] In the thermoelectric element used in the present invention, the thermoelectric semiconductor material constituting the P-type thermoelectric element and the N-type thermoelectric element is not particularly limited as long as it is a material that can generate thermoelectric power by applying a temperature difference, and examples thereof include bismuth-tellurium-based thermoelectric semiconductor materials such as P-type bismuth telluride and N-type bismuth telluride; telluride-based thermoelectric semiconductor materials such as GeTe and PbTe; antimony-tellurium-based thermoelectric semiconductor materials; ZnSb, ZnSb 2、 Zinc-antimony thermoelectric semiconductor materials such as Zn4Sb3; silicon-germanium thermoelectric semiconductor materials such as SiGe; bismuth selenide thermoelectric semiconductor materials such as Bi2Se3; β-FeSi2, CrSi2, MnSi 1.73 Examples of thermoelectric semiconductor materials that can be used include silicide-based thermoelectric semiconductor materials such as Mg2Si, oxide-based thermoelectric semiconductor materials, Heusler materials such as FeVAl, FeVAlSi, and FeVTiAl, and sulfide-based thermoelectric semiconductor materials such as TiS2.

[0036] The content of the thermoelectric semiconductor particles in the thermoelectric semiconductor composition is preferably 30 to 99% by mass, more preferably 50 to 96% by mass, and even more preferably 70 to 95% by mass. When the content of the thermoelectric semiconductor particles is within the above range, the Seebeck coefficient (absolute value of the Peltier coefficient) is large, and a decrease in electrical conductivity is suppressed, with only a decrease in thermal conductivity, so that a film exhibiting high thermoelectric performance and having sufficient film strength and flexibility is obtained, which is preferable.

[0037] Furthermore, the thermoelectric semiconductor particles are preferably subjected to an annealing treatment (hereinafter sometimes referred to as "annealing treatment A"). By performing annealing treatment A, the crystallinity of the thermoelectric semiconductor particles is improved, and furthermore, the surface oxide film of the thermoelectric semiconductor particles is removed, thereby increasing the Seebeck coefficient (absolute value of the Peltier coefficient) of the thermoelectric element layer and further improving the thermoelectric figure of merit.

[0038] (resin) The resin used in the present invention has the effect of physically bonding thermoelectric semiconductor particles together, thereby increasing the flexibility of the thermoelectric conversion module and facilitating the formation of a thin film by coating or the like. The resin is preferably a heat-resistant resin or a binder resin.

[0039] The heat-resistant resin maintains its physical properties such as mechanical strength and thermal conductivity without being impaired when the thin film made of the thermoelectric semiconductor composition is annealed or otherwise treated to cause crystal growth of thermoelectric semiconductor particles. The heat-resistant resin is preferably a polyamide resin, a polyamide-imide resin, a polyimide resin, or an epoxy resin, because it has higher heat resistance and does not adversely affect the crystal growth of the thermoelectric semiconductor particles in the thin film, and more preferably a polyamide resin, a polyamide-imide resin, or a polyimide resin, because it has excellent flexibility.

[0040] The heat-resistant resin preferably has a decomposition temperature of 300° C. or higher. If the decomposition temperature is within the above range, the resin will not lose its function as a binder and will be able to maintain flexibility even when a thin film made of the thermoelectric semiconductor composition is annealed, as will be described later.

[0041] The content of the heat-resistant resin in the thermoelectric semiconductor composition is 0.1 to 40 mass %, more preferably 1 to 20 mass %, and even more preferably 2 to 15 mass %. When the content of the heat-resistant resin is within the above range, it functions as a binder for the thermoelectric semiconductor particles, making it easier to form a thin film, and a film that combines high thermoelectric performance and film strength can be obtained.

[0042] The binder resin refers to a resin that decomposes at 90% by mass or more at the baking (annealing) temperature or higher, more preferably a resin that decomposes at 95% by mass or more, and particularly preferably a resin that decomposes at 99% by mass or more. If a resin that decomposes at 90% by mass or more at or above the firing (annealing) temperature, i.e., a resin that decomposes at a temperature lower than the heat-resistant resin described above, is used as the binder resin, the binder resin decomposes upon firing, reducing the content of the binder resin that serves as an insulating component in the fired body and promoting crystal growth of the thermoelectric semiconductor particles in the thermoelectric semiconductor composition, thereby reducing voids in the thermoelectric element and improving the filling rate. Whether or not a resin decomposes to a predetermined extent (e.g., 90% by mass) at or above the baking (annealing) temperature is determined by measuring the mass loss rate (the value obtained by dividing the mass after decomposition by the mass before decomposition) at the baking (annealing) temperature using thermogravimetry (TG).

[0043] Thermoplastic resins and curable resins can be used as such binder resins. Examples of thermoplastic resins include polyolefin resins such as polyethylene, polypropylene, polyisobutylene, and polymethylpentene; polycarbonate; thermoplastic polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polyvinyl polymers such as polystyrene, acrylonitrile-styrene copolymer, polyvinyl acetate, ethylene-vinyl acetate copolymer, vinyl chloride, polyvinylpyridine, polyvinyl alcohol, and polyvinylpyrrolidone; polyurethane; and cellulose derivatives such as ethyl cellulose. Examples of curable resins include thermosetting resins and photocurable resins. Examples of thermosetting resins include epoxy resins and phenolic resins. Examples of photocurable resins include photocurable acrylic resins, photocurable urethane resins, and photocurable epoxy resins. These resins may be used alone or in combination.

[0044] The binder resin is appropriately selected depending on the temperature of the annealing treatment of the thermoelectric semiconductor particles in the annealing treatment step. From the viewpoint of the electrical resistivity of the thermoelectric semiconductor particles in the thermoelectric element, it is preferable to perform the annealing treatment at a temperature equal to or higher than the final decomposition temperature of the binder resin. In this specification, the term "final decomposition temperature" refers to the temperature at which the mass reduction rate at the firing (annealing) temperature determined by thermogravimetry (TG) is 100% (the mass after decomposition is 0% of the mass before decomposition).

[0045] The final decomposition temperature of the binder resin is usually 150 to 600° C., and preferably 240 to 360° C. If a binder resin having a final decomposition temperature within this range is used, it functions as a binder for the thermoelectric semiconductor particles, facilitating the formation of a thin film during printing.

[0046] The content of the binder resin in the thermoelectric semiconductor composition is 0.1 to 40% by mass, preferably 0.5 to 10% by mass. When the content of the binder resin is within the above range, the electrical resistivity of the thermoelectric semiconductor particles in the thermoelectric element can be reduced.

[0047] The content of the binder resin in the thermoelectric element is preferably 0 to 10 mass %, more preferably 0 to 5 mass %, and particularly preferably 0 to 1 mass %. If the content of the binder resin in the thermoelectric conversion material is within the above range, the electrical resistivity of the thermoelectric semiconductor particles in the thermoelectric element can be reduced.

[0048] (ionic liquid) The ionic liquid that can be contained in the thermoelectric semiconductor composition is a molten salt formed by combining a cation and an anion, and refers to a salt that can exist in liquid form at any temperature range from -50°C to less than 400°C. In other words, an ionic liquid is an ionic compound with a melting point in the range of -50°C to less than 400°C. The melting point of the ionic liquid is preferably -25°C to 200°C, more preferably 0°C to 150°C. Ionic liquids have characteristics such as extremely low vapor pressure, nonvolatility, excellent thermal stability and electrochemical stability, low viscosity, and high ionic conductivity. Therefore, as a conductive additive, they can effectively suppress a decrease in electrical conductivity between thermoelectric semiconductor materials. Furthermore, ionic liquids exhibit high polarity due to their aprotic ionic structure and excellent compatibility with heat-resistant resins, thereby enabling the electrical conductivity of thermoelectric elements to be uniform.

[0049] The ionic liquid may be a known or commercially available one. For example, a nitrogen-containing cyclic cationic compound such as pyridinium, pyrimidinium, pyrazolium, pyrrolidinium, piperidinium, or imidazolium, or a derivative thereof; a tetraalkylammonium-based amine-based cation and a derivative thereof; a phosphine-based cation such as phosphonium, trialkylsulfonium, or tetraalkylphosphonium, or a derivative thereof; a lithium cation and a derivative thereof; or a mixture of a cation component and a Cl cation. - , Br - , I - , AlCl4 - , Al2Cl7 - , BF4 - , PF6 - , ClO4 - , NO3- , CH3COO - , CF3COO - , CH3SO3 - , CF3SO3 - , (FSO2)2N - , (CF3SO2)2N - , (CF3SO2)3C - , AsF6 - , SbF6 - , NbF6 - , TaF6 - , F(HF) n - , (CN)2N - , C4F9SO3 - , (C2F5SO2)2N - , C3F7COO - , (CF3SO2)(CF3CO)N - and an anion component such as the above.

[0050] Among the above-mentioned ionic liquids, from the viewpoints of high-temperature stability, compatibility with thermoelectric semiconductor particles and resins, and suppression of a decrease in the electrical conductivity in the gaps between thermoelectric semiconductor particles, it is preferred that the cationic component of the ionic liquid contains at least one selected from pyridinium cations and derivatives thereof, and imidazolium cations and derivatives thereof.

[0051] The ionic liquid preferably has a decomposition temperature of 300° C. or higher. If the decomposition temperature is within the above range, the ionic liquid can maintain its effect as a conductive additive even when a thin film made of the thermoelectric semiconductor composition is annealed, as described below.

[0052] The content of the ionic liquid in the thermoelectric semiconductor composition is preferably 0.01 to 50 mass %, more preferably 1.0 to 20 mass %. When the content of the ionic liquid is within the above range, a decrease in electrical conductivity is effectively suppressed, and a film with high thermoelectric performance is obtained.

[0053] (Method for preparing thermoelectric semiconductor composition) The method for preparing the thermoelectric semiconductor composition is not particularly limited, and the thermoelectric semiconductor composition may be prepared by, for example, mixing and dispersing the thermoelectric semiconductor particles, resin, and, if desired, the ionic liquid, the inorganic ionic compound, and other additives, and a solvent, using a known method such as an ultrasonic homogenizer, a spiral mixer, a planetary mixer, a disperser, or a hybrid mixer. Examples of the solvent include toluene, ethyl acetate, methyl ethyl ketone, alcohol, tetrahydrofuran, methylpyrrolidone, ethyl cellosolve, etc. These solvents may be used alone or in combination of two or more. The solids concentration of the thermoelectric semiconductor composition is not particularly limited as long as the composition has a viscosity suitable for coating.

[0054] The thermoelectric element made of the thermoelectric semiconductor composition is not particularly limited, but can be formed, for example, by applying the thermoelectric semiconductor composition to a substrate such as glass, alumina, silicon, or a resin film, or to a substrate on which a sacrificial layer (described later) is formed, to obtain a coating film, drying the film, and then separating the film from the substrate as appropriate to obtain a thermoelectric element. By forming the thermoelectric element in this manner, a large number of thermoelectric elements can be obtained easily and at low cost. The resin film is preferably heat-resistant, and films made of polyamide resin, polyamideimide resin, polyimide resin, etc. are preferred. Methods for applying the thermoelectric semiconductor composition to obtain a thermoelectric element include, but are not limited to, known methods such as screen printing, flexographic printing, gravure printing, spin coating, dip coating, die coating, spray coating, bar coating, doctor blade, etc. When forming a coating film in a pattern, screen printing, slot die coating, etc., which allow for easy pattern formation using a screen plate having a desired pattern, are preferably used. The resulting coating film is then dried to form a thermoelectric element, and any conventionally known drying method can be used as the drying method, such as hot air drying, hot roll drying, infrared irradiation, etc. The heating temperature is usually 80 to 150°C, and the heating time, which varies depending on the heating method, is usually several seconds to several tens of minutes. When a solvent is used in preparing the thermoelectric semiconductor composition, the heating temperature is not particularly limited as long as it is within a temperature range that allows the solvent used to be completely dried.

[0055] The thickness of the thin film made of the thermoelectric semiconductor composition is not particularly limited, but from the viewpoint of thermoelectric performance and film strength, it is preferably 100 nm to 1000 μm, more preferably 300 nm to 600 μm, and even more preferably 5 to 400 μm.

[0056] The thermoelectric element as a thin film made of the thermoelectric semiconductor composition is preferably further subjected to an annealing treatment (hereinafter, sometimes referred to as "annealing treatment B"). By performing annealing treatment B, the thermoelectric performance can be stabilized and the thermoelectric semiconductor particles in the thin film can undergo crystal growth, thereby further improving the thermoelectric performance. Although there are no particular limitations on annealing treatment B, it is usually performed at 100 to 800°C for several minutes to several tens of hours in an inert gas atmosphere such as nitrogen or argon, a reducing gas atmosphere, or under vacuum conditions with a controlled gas flow rate. Furthermore, in annealing treatment B, the thermoelectric semiconductor composition may be pressed to increase the density of the thermoelectric semiconductor composition.

[0057] <Method of manufacturing thermoelectric conversion module> In one embodiment, the method for producing a thermoelectric conversion module of the present invention preferably includes the following steps (a) to (j). (a) A step of preparing a P-type thermoelectric element and an N-type thermoelectric element (b) forming a first pressure-sensitive adhesive layer on the release layer of the first release sheet (c) forming a first conductive layer on the first adhesive layer (d) forming a solder material layer on the first conductive layer; (e) A step of placing a P-type thermoelectric element and an N-type thermoelectric element on the solder material layer to fabricate a thermoelectric conversion module intermediate 1 (f) forming a second pressure-sensitive adhesive layer on the release layer of the second release sheet (g) forming a second conductive layer on the second adhesive layer (h) A step of forming a solder material layer on the second conductive layer to produce a thermoelectric conversion module intermediate 2 (i) A step of bonding a thermoelectric conversion module intermediate 1 and a thermoelectric conversion module intermediate 2 facing each other to produce a thermoelectric conversion module precursor. (j) A step of reflowing the thermoelectric conversion module precursor to bond the thermoelectric conversion module intermediate 1 and the thermoelectric conversion module intermediate 2 via a solder material layer to form a thermoelectric conversion module. The steps included in the method for manufacturing a thermoelectric conversion module will be described below in order.

[0058] In the following explanation, the step (a) may be referred to as the "thermoelectric element preparation step", the steps (b) and (f) as the "adhesive layer formation step", the steps (c) and (g) as the "conductive layer formation step", the step (d) as the "solder material layer formation step", the step (e) as the "thermoelectric element placement step", the step (h) as the "thermoelectric conversion module intermediate 2 preparation step", the step (i) as the "thermoelectric conversion module precursor preparation step", and the step (j) as the "reflow treatment step".

[0059] (Preparation process of thermoelectric element) The thermoelectric element preparation step is the step (a) in the method for manufacturing a thermoelectric conversion module of the present invention. For example, a sacrificial layer (described later) is formed on a substrate such as glass, a coating film for the thermoelectric element is formed on the resulting sacrificial layer by the method described above, and then the resulting thermoelectric element is obtained by annealing (according to the conditions for annealing B described above). The resulting thermoelectric element is peeled off from the sacrificial layer on the substrate, and multiple individual thermoelectric elements are prepared. By using a sacrificial layer, a thermoelectric element formed on a substrate such as glass can be easily peeled off from the glass after annealing. The sacrificial layer can be made of a resin such as polymethyl methacrylate or polystyrene, or a release agent such as a fluorine-based release agent or a silicone-based release agent. The formation of the sacrificial layer is not particularly limited, and can be performed by a known method such as flexographic printing or spin coating.

[0060] (Adhesive layer formation process) The pressure-sensitive adhesive layer forming step is a step of forming a first pressure-sensitive adhesive layer on the release layer of a first release sheet in step (b) of the method for producing a thermoelectric conversion module of the present invention, and is also a step of forming a second pressure-sensitive adhesive layer on the release layer of a second release sheet in step (f). For example, it is a step of forming a pressure-sensitive adhesive layer by applying a pressure-sensitive adhesive resin onto a release sheet. The adhesive resin used in the adhesive layer, the thickness of the adhesive layer, the method for forming the adhesive layer, etc. are as described above. The configuration of the release sheet, the thickness of the first release sheet and the second release sheet, etc. are as described above.

[0061] (Conductive layer formation process) The conductive layer forming step is a step of forming a first conductive layer on the first adhesive layer in step (c) of the method for producing a thermoelectric conversion module of the present invention, and is also a step of forming a second conductive layer on the second adhesive layer in step (g). For example, it is a step of forming a conductive layer by depositing a metal layer on an adhesive layer and processing it into a predetermined pattern. The first and second conductive layers are made of the conductive layers described above. The metal material, metal oxide, conductive particles, thickness of the conductive layer, and method of forming the conductive layer are also the same as those described above.

[0062] (Solder material layer formation process) The solder material layer forming step is the step (d) [including step (h)] of the method for manufacturing a thermoelectric conversion module of the present invention, and is a step of forming a solder material layer on the first conductive layer and the second conductive layer. The solder material layer is used to join the thermoelectric element and the conductive layer. The solder material constituting the solder material layer may be appropriately selected taking into consideration the heat resistance temperature of the material constituting the thermoelectric conversion module, as well as the electrical conductivity and thermal conductivity of the solder material layer. Examples of known materials include Sn, Sn / Pb alloy, Sn / Ag alloy, Sn / Cu alloy, Sn / Sb alloy, Sn / In alloy, Sn / Zn alloy, Sn / In / Bi alloy, Sn / In / Bi / Zn alloy, Sn / Bi / Pb / Cd alloy, Sn / Bi / Pb alloy, Sn / Bi / Cd alloy, Bi / Pb alloy, Sn / Bi / Zn alloy, Sn / Bi alloy, Sn / Bi / Pb alloy, Sn / Pb / Cd alloy, and Sn / Cd alloy. From the viewpoints of lead-free and / or cadmium-free, melting point, electrical conductivity, and thermal conductivity, alloys such as 43Sn / 57Bi alloy, 42Sn / 58Bi alloy, 40Sn / 56Bi / 4Zn alloy, 48Sn / 52In alloy, and 39.8Sn / 52In / 7Bi / 1.2Zn alloy are preferred. Examples of commercially available solder materials include the following: 42Sn / 58Bi alloy (manufactured by Tamura Corporation, product name: SAM10-401-27) and 41Sn / 58Bi / Ag alloy (manufactured by Nippon Handa Co., Ltd., product name: PF141-LT7HO). The thickness of the solder material layer (after heating and cooling) is preferably 1 to 200 μm, more preferably 5 to 100 μm, and even more preferably 10 to 50 μm. When the thickness of the solder material layer is within this range, adhesion between the thermoelectric element and the conductive layer can be easily obtained. Methods for applying the solder material include known methods such as stencil printing, screen printing, dispensing, etc. The heating temperature varies depending on the solder material, resin film, etc. used, but is usually performed at 150 to 280°C for 1 to 20 minutes.

[0063] (Thermoelectric element placement process) The thermoelectric element mounting step is the step (e) in the method for manufacturing a thermoelectric conversion module of the present invention, and is a step of mounting one surface of the thermoelectric element prepared in the step (a) on the solder material layer obtained in the step (d) to produce a thermoelectric conversion module intermediate 1. For example, it is a step of mounting one surface of a P-type thermoelectric element and one surface of an N-type thermoelectric element on the upper surface of the corresponding solder material layer on the solder material layer on the conductive layer. Depending on the application, the P-type thermoelectric elements and N-type thermoelectric elements may be arranged in a combination of the same type, or in a random combination, such as "NPPN", "PNPP", etc. From the viewpoint of theoretically obtaining high thermoelectric performance, in the present invention, multiple pairs of P-type and N-type thermoelectric elements are arranged with electrodes interposed between them. The method for placing the thermoelectric element on the solder material layer is not particularly limited, and any known method can be used, such as handling one or more thermoelectric elements using a chip mounter or the like, aligning them with a camera or the like, and then placing them. From the viewpoints of ease of handling, placement accuracy, and mass productivity, it is preferable to place the thermoelectric element using the chip mounter described above.

[0064] (Thermoelectric conversion module intermediate 2 manufacturing process) The thermoelectric conversion module intermediate 2 manufacturing process is the step (h) of the thermoelectric conversion module manufacturing method of the present invention, and is a process of forming a solder material layer on the second conductive layer obtained in the step (g) to manufacture the thermoelectric conversion module intermediate 2. The material used for the solder material layer, the thickness of the solder material layer, the method for forming the solder material layer, etc. are as described above.

[0065] (Thermoelectric conversion module precursor manufacturing process) The thermoelectric conversion module precursor preparation step is step (i) of the thermoelectric conversion module manufacturing method of the present invention. This step involves facing the exposed surface of the thermoelectric element of the thermoelectric conversion module intermediate 1 obtained in step (h) and the solder material layer on the second conductive layer of the thermoelectric conversion module intermediate 2 produced in step (e), aligning them so as to form a π-type thermoelectric conversion element, and bonding them together to prepare a thermoelectric conversion module precursor. The bonding method can be a known method.

[0066] (Reflow processing process) The reflow treatment step is step (j) in the method for producing a thermoelectric conversion module of the present invention, This is a step of forming a thermoelectric conversion module from the thermoelectric conversion module precursor by reflow processing the thermoelectric conversion module precursor produced in step (i). After completion of this step, a thermoelectric conversion module is obtained. The reflow treatment is carried out, for example, by placing the thermoelectric conversion module precursor inside a heating furnace and heating or heating and pressurizing it. The heating in the reflow treatment depends on the melting temperature of the solder material layer, etc., but is usually carried out in an atmosphere of 120 to 350°C for 1 to 60 minutes, preferably in an atmosphere of 160 to 320°C for 3 to 40 minutes. The pressure is preferably 0.05 to 10 MPa, more preferably 0.1 to 5 MPa, and even more preferably 0.2 to 3 MPa. When the heating or heating and pressurizing conditions are within this range, displacement of the thermoelectric element relative to the conductive layer due to melting of the solder material is suppressed, and accurate joining can be achieved.

[0067] In another embodiment, the method for manufacturing a thermoelectric conversion module of the present invention may include a step of patterning the first adhesive layer instead of step (b) of forming a first adhesive layer on the release layer of the first release sheet in the above-mentioned steps (a) to (j). The material used for the first pressure-sensitive adhesive layer, the thickness of the first pressure-sensitive adhesive layer, the method for forming the pattern of the first pressure-sensitive adhesive layer, etc. are as described above.

[0068] In the thermoelectric conversion module of the present invention, the first release sheet functions as a support substrate during the manufacturing process, preventing deformation and damage during transportation and handling, and the module is thinned after the first and second release sheets are peeled off. Furthermore, since the gap between the P-type thermoelectric element and the N-type thermoelectric element is maintained, the thermoelectric conversion module has reduced thermal resistance. [Example]

[0069] Next, the present invention will be described in more detail with reference to examples, but the present invention is not limited to these examples in any way.

[0070] The thermoelectric modules produced in the examples and comparative examples were evaluated for handling, peeling and adhering, peeling force, and curvature by the following methods.

[0071] (a) Handling evaluation The thermoelectric conversion modules produced in Example 1 and Comparative Example 1 were allowed to drop freely from a height of 50 cm from a resin floor. The electrical resistance (current-carrying state) between the extraction electrodes of the thermoelectric conversion modules before and after the drop test was measured using a Digital HiTester (manufactured by Hioki E.E. Corporation, model number: 3801-50), and evaluated according to the following evaluation criteria. ○: Electricity is flowing (there is no change in electrical resistance value before and after the test). ×: No current is applied (electrical resistance value changes to infinity after the test).

[0072] (b) Peel-off and stick-on evaluation A simulated thermoelectric conversion device was fabricated by peeling off the first release sheet from 10 samples each of the thermoelectric conversion modules fabricated in Example 1 and Comparative Example 1, attaching them to a pre-prepared SUS plate, then peeling off the second release sheet, and attaching a copper plate. The electrical resistance (current-carrying state) between the extraction electrodes of the thermoelectric conversion module in the device was measured using a Digital HiTester (manufactured by Hioki E.E. Corporation, model number: 3801-50), and evaluated according to the following evaluation criteria. ◎: All 10 samples are powered on. ○: Power is supplied to 9 to 5 of the 10 samples. ×: Electricity was applied to 4 to 0 of the 10 samples.

[0073] (c) Peeling force evaluation One release sheet was peeled off from each of the thermoelectric conversion modules produced in Example 1 and Comparative Example 1, and the modules were attached and fixed to a SUS plate. The remaining release sheet was then peeled off using a universal tensile tester (Shimadzu Corporation, Autograph (registered trademark) AG-IS) at a temperature of 23°C, a peel angle of 180°, and a peel rate of 300 mm / min, all other conditions conforming to JIS Z0237:2009, and the load at this time was measured. The results are shown in Table 1.

[0074] (d) Curvature evaluation The first and second release sheets used in Example 1 were each cut to a length of 250 mm and a width of 50 mm, and the radius of the circle drawn by the sheet when hung from its center point was measured. The radius of the first release sheet was 1000, but the radius of the second release sheet was impossible to measure because both ends drooped and did not form a circle.

[0075] Example 1 <Fabrication of thermoelectric conversion module> (1) Preparation of thermoelectric element P-type thermoelectric wafers (BiSbTe) and N-type thermoelectric wafers (BiTe) manufactured by Toshima Manufacturing Co., Ltd. were diced to prepare rectangular parallelepiped P-type and N-type thermoelectric elements, each measuring 1 mm long x 1 mm wide and 300 μm thick. (2) Manufacturing of semi-finished thermoelectric conversion module (intermediate) To 100 parts by mass of an acrylic polymer having a weight-average molecular weight of 700,000 and containing 47% by mass of butyl acrylate, 47% by mass of 2-ethylhexyl acrylate, 5% by mass of acrylic acid, and 1% by mass of 2-hydroxypropyl acrylate, 1.0 part by mass (expressed as a solid content equivalent value) of trimethylolpropane-modified tolylene diisocyanate (manufactured by Toyochem Co., Ltd., product name "BHS8515") and 0.28 part by mass of 3-glycidoxypropyltrimethoxysilane were added, and the mixture was diluted with ethyl acetate to obtain a coating liquid. The coating solution was applied using an applicator to the release layer of a polyethylene terephthalate release film (manufactured by Lintec Corporation, 110 μm thick) serving as a first release sheet, dried at 90°C for 1 minute, and then aged for 7 days at 23°C and 50% RH to obtain a 15 μm thick first adhesive layer. Next, copper foil (30 μm thick) was attached to the first adhesive layer, and a first conductive layer made of copper foil was patterned by photolithography. SnBi solder material (manufactured by Kokisha, product name: lead-free solder paste, thickness: 20 μm) was applied to predetermined positions on the obtained first conductive layer. 80 pairs of P-type thermoelectric elements and N-type thermoelectric elements prepared in (1) were arranged on the first conductive layer so as to be alternately connected in series, and soldered by heating at 190°C for 1 minute to obtain a thermoelectric conversion module intermediate 1. (3) Formation of thermoelectric conversion module precursor Next, the coating liquid was applied onto the release layer of a polyethylene terephthalate release film (manufactured by Lintec Corporation, thickness 50 μm) serving as a second release sheet, and a second adhesive layer 15 μm thick was formed by undergoing the same process. Next, copper foil (thickness: 30 μm) was attached onto the second adhesive layer, and then a second conductive layer made of copper foil was patterned by photolithography, and a SnBi solder material (manufactured by Kokisha, product name: lead-free solder paste, thickness: 20 μm) was applied to a predetermined position on the obtained second conductive layer to obtain a thermoelectric conversion module intermediate 2. The solder on the second conductive layer surface of the intermediate 2 and the exposed surface side of the thermoelectric element of the thermoelectric conversion module intermediate 1 obtained in (2) were overlapped so as to form a π-type thermoelectric conversion element, thereby obtaining a thermoelectric conversion module precursor. (4) Fabrication of thermoelectric conversion module Next, the thermoelectric conversion module precursor was heated at 190°C for 1 minute using a hot plate (manufactured by AS-ONE, model name: HS-2SA) to solder the thermoelectric element layer on the second conductive layer side to the second conductive layer. After that, a ceramic weight was placed on top, and a heat compression treatment was performed under conditions of 0.3 MPa, 100°C, and 10 minutes, resulting in a thermoelectric conversion module shown in Figure 1 (Configuration A; including release film), in which a gap was formed between the P-type thermoelectric element and the N-type thermoelectric element and the thermoelectric element was covered with an adhesive layer up to the boundary between the thermoelectric element and the conductive layer.

[0076] (Comparative Example 1) A thermoelectric conversion module of Comparative Example 1 (Configuration B; including release film) was obtained in the same manner as in Example 1, except that the first release sheet used in Example 1 was changed to the second release sheet used in Example 1.

[0077] The thermoelectric conversion modules obtained in Example 1 and Comparative Example 1 were evaluated for handleability, peeling and adhesion, peeling force, and curvature. Table 1 shows the evaluation results.

[0078] [Table 1]

[0079] Table 1 shows that the thermoelectric conversion module of Example 1, which satisfies the requirements of the present invention, has a first release sheet that functions as a support substrate during the manufacturing process, and is less susceptible to deformation and damage during transportation and handling, compared to the thermoelectric conversion module of Comparative Example 1, which does not satisfy the requirements of the present invention. [Industrial Applicability]

[0080] The thermoelectric conversion module of the present invention includes a release sheet that functions as a support substrate during the manufacturing process and is suppressed from deformation and damage during transportation and handling, making it suitable for use in the manufacturing process of thermoelectric conversion modules. The resulting thermoelectric conversion module can be made thinner than conventional products by removing the release sheet. Therefore, for example, the module can be used for cooling applications in the field of electronics, such as temperature control of various sensors, including central processing units (CPUs) used in smartphones and various computers, image sensors such as complementary metal oxide semiconductor image sensors (CMOSs) and charge coupled devices (CCDs), and microelectromechanical systems (MEMSs) and other light-receiving elements. [Explanation of symbols]

[0081] 1: Thermoelectric conversion module 2: Thermoelectric element layer 2p:P type thermoelectric element 2n:N type thermoelectric element 2a: Second surface of thermoelectric element layer 2 2b: First surface of thermoelectric element layer 2 3a: Second adhesive layer 3b: 1st adhesive layer 4a: Second conductive layer 4b: First conductive layer 5a: Second release sheet 5b: First release sheet 11: Thermoelectric conversion module 12: Thermoelectric element layer 12p: P-type thermoelectric element 12n:N-type thermoelectric element 12a: Second surface of thermoelectric element layer 2 12b: First surface of thermoelectric element layer 2 13a: Second adhesive layer 13b: First adhesive layer 14a: second conductive layer 14b: First conductive layer 15a: Second release sheet 15b: First release sheet

Claims

1. a thermoelectric element layer in which P-type thermoelectric elements and N-type thermoelectric elements are alternately arranged so as to be electrically connected in series; a first conductive layer provided on a first surface of the thermoelectric element layer; a first adhesive layer provided on a surface of the first conductive layer opposite to a surface on the thermoelectric element layer side; a first release sheet provided on a surface of the first pressure-sensitive adhesive layer opposite to a surface on the first conductive layer side; It has A thermoelectric conversion module, wherein the curvature of the first release sheet is R1000 or more when the first release sheet is cut into a length of 250 mm and hung at the center in the length direction.

2. The thermoelectric conversion module according to claim 1 , further comprising a second conductive layer provided on a second surface of the thermoelectric element layer opposite to the first surface.

3. The thermoelectric conversion module according to claim 2 , further comprising a second adhesive layer provided on a surface of the second conductive layer opposite to the surface on the thermoelectric element layer side.

4. The thermoelectric conversion module according to claim 3 , further comprising a second release sheet provided on the surface of the second pressure-sensitive adhesive layer opposite to the surface on the second conductive layer side.

5. The thermoelectric conversion module according to claim 4 , wherein the peeling strength of the first release sheet is greater than or less than the peeling strength of the second release sheet.

6. 3. The thermoelectric conversion module according to claim 1, wherein the first adhesive layer is a patterned layer made of an adhesive composition, and the surface of the first conductive layer is in contact with a surface of the patterned layer having the same shape as the surface of the first conductive layer.

7. The thermoelectric conversion module according to claim 1 or 2, wherein the first adhesive layer is a solid layer made of an adhesive composition, and the surface of the first conductive layer is in contact with the surface of a portion of the solid layer.

8. The thermoelectric conversion module according to claim 1 , further comprising a gap formed between the P-type thermoelectric element layer and the N-type thermoelectric element layer.

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