Method for manufacturing a thermoelectric conversion module

Abstract

To provide a method for manufacturing a thermoelectric conversion module capable of achieving high output.SOLUTION: A method for manufacturing a thermoelectric conversion module includes, in the following order, a first step of preparing a substrate having a first main surface on which a first electrode and a second electrode spaced apart from each other are arranged, a second step of arranging a dam material having an opening portion on the first main surface, a third step of supplying a dispersion liquid including dispersed thermoelectric conversion material therein to the opening portion, a fourth step of removing the dam material, and a fifth step of heating the substrate from a second main surface side located on an opposite side to the first main surface in the thickness direction of the substrate to form a thermoelectric conversion layer in contact with the first electrode and the second electrode.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a method for manufacturing a thermoelectric conversion module.

Background Art

[0002] In order to perform power generation using geothermal heat or waste heat from factories, etc., a thermoelectric conversion element may be used. Patent Document 1 below discloses an aspect in which a flexible substrate having a pattern layer composed of a resin layer and a metal layer is provided on both sides of a thermoelectric conversion module having a p-type thermoelectric element material and an n-type thermoelectric element material. In Patent Document 1 below, the metal layer included in one flexible substrate overlaps with one electrode included in the thermoelectric conversion module, and the metal layer included in the other flexible substrate overlaps with the other electrode included in the thermoelectric conversion module. In the above aspect, by setting one flexible substrate to a high temperature state and the other flexible substrate to a low temperature state, a temperature difference occurs in the plane direction of the thermoelectric conversion module. As a result, an electromotive force is generated in the thermoelectric conversion module.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] In the thermoelectric conversion element as described above, higher output is required. For this reason, an object of one aspect of the present invention is to provide a method for manufacturing a thermoelectric conversion module capable of achieving higher output.

Means for Solving the Problems

[0005] The method for manufacturing a thermoelectric conversion module according to one aspect of the present invention is as follows. [1] A first step of preparing a substrate having a first main surface on which a first electrode and a second electrode spaced apart from each other are disposed; a second step of disposing a dam material having an opening on the first main surface; a third step of supplying a dispersion liquid in which a thermoelectric conversion material is dispersed to the opening; a fourth step of removing the dam material; and a fifth step of heating the substrate from the second main surface side located on the opposite side of the first main surface in the thickness direction of the substrate to form a thermoelectric conversion layer in contact with the first electrode and the second electrode. A method for manufacturing a thermoelectric conversion module, which comprises the steps in order. [2] The height of the dam material is 0.5 times or more and 2 times or less the length of the short side of the thermoelectric conversion layer in plan view. The manufacturing method according to [1]. [3] The thermoelectric conversion material includes carbon nanotubes and a conductive polymer composed of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid. The content of the carbon nanotubes is 25% by mass or more and 95% by mass or less based on the total amount of the conductive polymer and the carbon nanotubes. The manufacturing method according to [1] or [2]. [4] The total mass concentration of the carbon nanotubes and the conductive polymer in the dispersion liquid is 0.05% by mass or more. The manufacturing method according to any one of [1] to [3]. [5] The shear rate is 0.01 s -1 The viscosity of the dispersion liquid at is 10 4 mPa·sec or more and 10 8 mPa·sec or less. The manufacturing method according to any one of [1] to [4]. [6] In the fifth step, the substrate is heated at 25°C or more and 90°C or less. The manufacturing method according to any one of [1] to [5]. [7] In the fifth step, the substrate is heated in an air atmosphere. The manufacturing method according to any one of [1] to [6]. [8] Further comprising a sixth step of forming another thermoelectric conversion layer having a polarity different from that of the thermoelectric conversion layer, the first electrode having a first portion in contact with the thermoelectric conversion layer and a second portion in contact with another thermoelectric conversion layer, and in the second step and the third step, the second portion overlaps the dam material. The manufacturing method according to any one of [1] to [7]. [9] In the first step, the second portion is covered with a mask, and in the fifth step, the mask is removed after heating the substrate. The manufacturing method according to [8].

Advantages of the Invention

[0006] According to one aspect of the present invention, a method for manufacturing a thermoelectric conversion module capable of achieving high output can be provided.

Brief Description of the Drawings

[0007]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Embodiments for Carrying Out the Invention

[0008] Hereinafter, embodiments according to one aspect of the present invention will be described in detail with reference to the accompanying drawings. In the following description, the same reference numerals will be used for elements having the same element or the same function, and redundant descriptions will be omitted. Note that the terms "identical" and similar words in this specification are not limited to "completely identical".

[0009] First, while referring to FIG. 1, the configuration of the thermoelectric conversion module according to the present embodiment will be described. FIG. 1(a) is a schematic plan view showing the thermoelectric conversion module according to the present embodiment. FIG. 1(b) is an end view taken along line A-A of FIG. 1(a). The thermoelectric conversion module 1 shown in FIG. 1(a) is a device capable of generating electricity when heat is supplied from the outside. The thermoelectric conversion module 1 includes a substrate 2, a plurality of first electrodes 3, a plurality of second electrodes 4, a coverlay 5, a plurality of p-type thermoelectric conversion layers 6 (thermoelectric conversion layers), and a plurality of n-type thermoelectric conversion layers 7 (another thermoelectric conversion layer). A first terminal 8 and a second terminal 9 are connected to the thermoelectric conversion module 1.

[0010] A plurality of thermoelectric conversion elements 100 are provided in the thermoelectric conversion module 1. Each thermoelectric conversion element 100 is, for example, an element that converts heat into electricity using the temperature difference inside. Each thermoelectric conversion element 100 includes a p-type thermoelectric conversion layer 6, a first electrode 3 and a second electrode 4 that are in contact with the p-type thermoelectric conversion layer 6, an n-type thermoelectric conversion layer 7 that is in contact with the second electrode 4 and is located adjacent to the p-type thermoelectric conversion layer 6, and another first electrode 3 that is in contact with the n-type thermoelectric conversion layer 7. The thermoelectric conversion element 100 is a so-called in-plane type element. Therefore, the thermoelectric conversion element 100 tends to be superior in processability and flexibility compared to, for example, a π-type element (cross-plane type element). Thus, the thermoelectric conversion module 1 can be provided along the side surface of, for example, a cylindrical pipe used for recovering factory exhaust heat. That is, the thermoelectric conversion module 1 can be easily arranged at various locations. Therefore, the thermoelectric conversion module 1 is used, for example, as a power source for a plant sensor that utilizes exhaust heat. Hereinafter, the temperature of each component of the thermoelectric conversion module 1 is assumed to be measured under natural convection conditions of air.

[0011] The substrate 2 is, for example, a resin sheet member having a substantially flat plate shape, and exhibits heat resistance and flexibility. The thickness of the substrate 2 is, for example, 1 μm or more and 1000 μm or less. In the present embodiment, the substrate 2 has a main surface 2a (first main surface) and a main surface 2b (second main surface) located on the opposite side of the main surface 2a. In the present embodiment, the shapes of the main surfaces 2a and 2b are rectangular, but are not limited thereto. The shapes of the main surfaces 2a and 2b may be polygonal, circular, elliptical, or the like. In the following description, the short side direction of the main surface 2a is defined as the first direction X, the long side direction of the main surface 2a is defined as the second direction Y, and the thickness direction of the substrate 2 is defined as the third direction Z. Also, looking from the third direction Z corresponds to a plan view.

[0012] The resin constituting the substrate 2 is, for example, a (meth)acrylic resin, a (meth)acrylonitrile resin, a polyamide resin, a polycarbonate resin, a polyether resin, a polyester resin, an epoxy resin, an organosiloxane resin, a polyimide resin, a polysulfone resin, or the like. The thermal conductivity of the substrate 2 is, for example, 0.1 W / mK (corresponding to 0.1 watt per meter per kelvin, and 0.1 W×m -1 ×K -1 ) or more and 1 W / mK or less. Since the thermal conductivity of the substrate 2 is 1 W / mK or less, a temperature difference can occur inside the thermoelectric conversion module 1 (particularly, between the p-type thermoelectric conversion layer 6 and the n-type thermoelectric conversion layer 7). The thermal conductivity of the substrate 2 is measured, for example, by the following method. First, a piece cut out from the substrate 2 to 10 mm×10 mm is used as a test piece. Then, the thermal diffusivity, specific heat, and density of the test piece are measured, and the thermal conductivity is calculated from the following formula: "(thermal conductivity) = (thermal diffusivity)×(specific heat)×(density)". The thermal diffusivity of the test piece is measured, for example, by the laser flash method. The specific heat of the test piece is measured, for example, by differential scanning calorimetry. The density of the test piece is measured, for example, by the Archimedes method. All measurements are carried out under room temperature conditions (25 °C).

[0013] The plurality of first electrodes 3 are members that constitute the terminals of the thermoelectric conversion element 100 and are conductors provided on the main surface 2a of the substrate 2. The plurality of first electrodes 3 are located on one end side of the main surface 2a in the first direction X and are arranged along the second direction Y. The gap S1 located between two adjacent first electrodes 3 overlaps the second electrode 4 in the first direction X. The shape of the first electrode 3 in plan view is not particularly limited, and is, for example, a polygonal shape, a circular shape, an elliptical shape, or the like. The first electrode 3 is, for example, a conductor made of metal, alloy, conductive resin, or the like. When the first electrode 3 is made of metal or alloy, the first electrode 3 is formed on the substrate 2 by, for example, various dry methods. The dry method is, for example, a physical vapor deposition method (PVD method), patterning of a metal foil or alloy foil, or the like. The first electrode 3 may be formed using a nanopaste in which metal particles are dispersed. In the present embodiment, the first electrode 3 is formed by etching a copper-clad laminate and performing nickel plating and gold plating on the laminate. The thickness of the first electrode 3 is, for example, 1 μm or more and 100 μm or less. The thermal conductivity of the first electrode 3 is, for example, 5 W / mK or more. In this case, the first electrode 3 tends to be easily heated or cooled from the outside. The thermal conductivity of the first electrode 3 may be, for example, 30 W / mK or more.

[0014] The plurality of second electrodes 4 are, like the first electrodes 3, members that constitute the terminals included in the thermoelectric conversion element 100 and are conductors provided on the main surface 2a of the substrate 2. The plurality of second electrodes 4 are located on the other end side of the main surface 2a in the first direction X and are arranged along the second direction Y. The gap S2 located between two adjacent second electrodes 4 overlaps the first electrode 3 in the first direction X. From the viewpoint of generating a temperature difference between the first electrode 3 and the second electrode 4, the second electrode 4 is spaced apart from the first electrode 3. In the present embodiment, the second electrode 4 is formed simultaneously with the first electrode 3. For this reason, the second electrode 4 is composed of the same material as the first electrode 3. The shape of the second electrode 4 in plan view is not particularly limited, and is, for example, a polygonal shape, a circular shape, an elliptical shape, or the like. Also, the thermal conductivity of the second electrode 4 is, like the first electrode 3, for example, 5 W / mK or more. The thermal conductivity of the second electrode 4 may be, for example, 30 W / mK or more.

[0015] The coverlay 5 is a member that protects, for example, the first electrode 3 and the second electrode 4, and is provided on the main surface 2a of the substrate 2. The coverlay 5 is, for example, a resin film or a resist processing member. In the former case, for example, a pre-processed film is attached to the main surface 2a of the substrate 2, the first electrode 3, and the second electrode 4, thereby forming the coverlay 5. In the latter case, the coverlay 5 is formed, for example, by photolithography or the like. The resin constituting the coverlay 5 is, for example, a polyimide-based resin, a polyester-based resin, an epoxy-based resin, or the like. The thickness of the coverlay 5 is, for example, 10 μm or more, 20 μm or more, or 25 μm or more, and 100 μm or less, 80 μm or less, or 60 μm or less. The thermal conductivity of the coverlay 5 is, for example, 0.1 W / mK or more and 1 W / mK or less. The coverlay 5 has a plurality of first openings 11, a plurality of second openings 12, and a plurality of third openings 13.

[0016] Each of the plurality of first openings 11 overlaps one of the plurality of first electrodes 3. For this reason, a part of each first electrode 3 is exposed by the first opening 11. The shape of the first opening 11 is circular in plan view, but is not limited thereto. The plurality of first openings 11 has an opening 11a located at the most one end side in the second direction Y and a plurality of openings 11b different from the opening 11a. The opening 11a is located at the central portion of the main surface 2a in the first direction X and houses the first terminal 8. Each opening 11b is a portion that exposes a part of the corresponding first electrode 3 for conduction confirmation and is located at one end side of the main surface 2a in the first direction X. In plan view, each opening 11b overlaps the corresponding gap S2 in the first direction X, but is not limited thereto.

[0017] Each of the plurality of second openings 12 overlaps one of the plurality of second electrodes 4. Therefore, a part of each second electrode 4 is exposed by the second opening 12. The shape of the second opening 12 is circular in plan view, but is not limited thereto. The second opening 12 has an opening 12a located at the most other end side in the second direction Y and a plurality of openings 12b different from the opening 12a. The opening 12a is located at the center of the main surface 2a in the first direction X and houses the second terminal 9. Each opening 12b is a portion that exposes a part of the corresponding second electrode 4 for conduction confirmation and is located on the other end side of the main surface 2a in the first direction X. In plan view, each opening 12b overlaps the corresponding gap S1 in the first direction X, but is not limited thereto.

[0018] Each of the plurality of third openings 13 overlaps one of the plurality of first electrodes 3 and one of the plurality of second electrodes 4. Therefore, another part of each first electrode 3 and another part of each second electrode 4 are exposed by the third opening 13. In addition, a portion of the main surface 2a located between the other parts is also exposed by the third opening 13. The shape of the third opening 13 is rectangular in plan view, but is not limited thereto. In the present embodiment, the length L1 of the long side of the third opening 13 along the first direction X is 30% or more and 300% or less of the length L2 of the short side of the third opening 13 along the second direction Y. In addition, within each third opening 13, the length L3 of the gap S3 between the first electrode 3 and the second electrode 4 along the first direction X is 20% or more and 90% or less of the length L1. From the viewpoint of the temperature gradient along the first direction X in each of the p-type thermoelectric conversion layer 6 and the n-type thermoelectric conversion layer 7, the length L3 may be 25% or more of the length L1.

[0019] The plurality of third openings 13 are located at the central portion of the main surface 2a in the first direction X and are arranged along the second direction Y. The plurality of third openings 13 are located between the openings 11a and 12a in the second direction Y, but are not limited thereto. The plurality of third openings 13 have an opening 13a for accommodating the p-type thermoelectric conversion layer 6 and an opening 13b for accommodating the n-type thermoelectric conversion layer 7. The opening 13a and the opening 13b are alternately arranged along the second direction Y. Therefore, on the main surface 2a, the p-type thermoelectric conversion layer 6 and the n-type thermoelectric conversion layer 7 are alternately arranged along the second direction Y.

[0020] Each of the plurality of p-type thermoelectric conversion layers 6 is, for example, a p-type semiconductor layer and is accommodated in any one of the openings 13a. The shape of each p-type thermoelectric conversion layer 6 follows the shape of the third opening 13. Therefore, in plan view, the length of the long side of the p-type thermoelectric conversion layer 6 corresponds to the length L1, and the length of the short side of the p-type thermoelectric conversion layer 6 corresponds to the length L2. Each p-type thermoelectric conversion layer 6 contacts any one of the plurality of first electrodes 3 and any one of the plurality of second electrodes 4. The p-type thermoelectric conversion layer 6 is formed, for example, by various dry methods or wet methods. The wet method is, for example, a doctor blade method, a dip coating method, a spray coating method, a spin coating method, an inkjet method, etc. The thickness of the p-type thermoelectric conversion layer 6 is, for example, 1 μm or more and 500 μm or less. The thermal conductivity of the p-type thermoelectric conversion layer 6 is, for example, 0.01 W / mK or more and 200 W / mK or less. In this case, a temperature gradient can be easily formed inside the p-type thermoelectric conversion layer 6. Note that the thickness of the p-type thermoelectric conversion layer 6 corresponds to the thickness of the portion that does not overlap with the first electrode 3 and the second electrode 4 in the third direction Z. Also, the portion of the p-type thermoelectric conversion layer 6 that overlaps with the gap S3 is the portion that mainly exhibits the function of the p-type thermoelectric conversion layer 6 in the thermoelectric conversion element 100. The thermal conductivity of the p-type thermoelectric conversion layer 6 is calculated, for example, in the same manner as the substrate 2. The thermal diffusivity of the p-type thermoelectric conversion layer 6 is measured, for example, by using a thermal diffusivity measuring device (such as "Thermo Wave Analyzer TA" manufactured by BETEL Co., Ltd.) to measure the in-plane thermal diffusivity.

[0021] The thermoelectric conversion material contained in the p-type thermoelectric conversion layer 6 includes, for example, carbon nanotubes and a conductive polymer different from the carbon nanotubes. The carbon nanotubes may be any of single-layer, bilayer, and multi-layer. From the viewpoint of the electrical conductivity of the thermoelectric conversion material, single-walled carbon nanotubes (SWCNT) may be used. As an evaluation method of single-walled carbon nanotubes, for example, the G / D ratio in laser Raman spectroscopy is known. The G / D ratio of single-walled carbon nanotubes in laser Raman spectroscopy with a wavelength of 532 nm may be 10 or more, or may be 20 or more. The conductive polymer includes polyaniline-based conductive polymers, polythiophene-based conductive polymers, polypyrrole-based conductive polymers, polyacetylene-based conductive polymers, polyphenylene-based conductive polymers, polyphenylene vinylene-based conductive polymers, etc. A specific example of the conductive polymer is, for example, poly(3,4-ethylenedioxythiophene) (PEDOT). In this case, from the viewpoint of improving the electrical conductivity of the thermoelectric conversion material, polystyrene sulfonic acid (PSS) or the like may be used as an electron acceptor. In the p-type thermoelectric conversion layer 6, the carbon nanotubes and the conductive polymer may aggregate. Further, the p-type thermoelectric conversion layer 6 may include a porous structure in which carbon nanotubes are bound to each other by a conductive polymer.

[0022] Each of the plurality of n-type thermoelectric conversion layers 7 is, for example, an n-type semiconductor layer and is housed in any of the openings 13b. The shape of each n-type thermoelectric conversion layer 7 follows the shape of the third opening 13. Therefore, in plan view, the length of the long side of the n-type thermoelectric conversion layer 7 corresponds to the length L1, and the length of the short side of the n-type thermoelectric conversion layer 7 corresponds to the length L2. Each n-type thermoelectric conversion layer 7 contacts any one of the plurality of first electrodes 3 and any one of the plurality of second electrodes 4. Similar to the p-type thermoelectric conversion layer 6, the portion of the n-type thermoelectric conversion layer 7 that overlaps the gap S3 mainly functions as a thermoelectric conversion layer. The thermoelectric conversion material contained in the n-type thermoelectric conversion layer 7 includes, for example, a composite of an inorganic substance and an organic substance, or a composite of a plurality of organic substances. The inorganic substance is, for example, titanium sulfide (TiS 2 ), bismuth telluride (Bi 2 Te 3) include skutterudite, nickel (Ni), etc. The organic material is, for example, tetrathiafulvalene - tetracyanoquinodimethane (TTF - TCNQ), etc. The n - type thermoelectric conversion layer 7 is formed, for example, by various dry methods or wet methods. The thickness of the n - type thermoelectric conversion layer 7 is, for example, 1 μm or more and 500 μm or less. The thermal conductivity of the n - type thermoelectric conversion layer 7 is, for example, 0.01 W / mK or more and 200 W / mK or less. In this case, a temperature gradient can be easily formed inside the n - type thermoelectric conversion layer 7. Note that the thickness of the n - type thermoelectric conversion layer 7 corresponds to the thickness of the portion that does not overlap with the first electrode 3 and the second electrode 4 in the third direction Z. Also, the portion of the n - type thermoelectric conversion layer 7 that overlaps with the gap S3 is the portion that mainly exhibits the function of the n - type thermoelectric conversion layer 7 in the thermoelectric conversion element 100.

[0023] Each of the first terminal 8 and the second terminal 9 connected to the thermoelectric conversion module 1 is a conductive member for connecting the thermoelectric conversion module 1 and an external device. The first terminal 8 is connected to the first electrode 3 through the opening 11a of the first opening 11. The second terminal 9 is connected to the second electrode 4 through the opening 12a of the second opening 12. Each of the first terminal 8 and the second terminal 9 is, for example, a fastening member having conductivity, solder, etc.

[0024] Next, an example of the manufacturing method of the thermoelectric conversion module 1 will be described with reference to FIGS. 2 to 6. FIG. 2(a) is a schematic plan view for explaining the manufacturing method of the thermoelectric conversion module 1. FIGS. 2(b) and 3 to 6 are schematic end views for explaining the manufacturing method of the thermoelectric conversion module 1. In addition, FIG. 2(b) is an end view along the line B - B in FIG. 2(a).

[0025] First, as shown in FIGS. 2(a) and 2(b), a substrate 2 having a main surface 2a on which a first electrode 3 and a second electrode 4 spaced apart from each other are disposed is prepared (first step). In the first step, a substrate 2 provided with a plurality of first electrodes 3, a plurality of second electrodes 4, and a coverlay 5 is prepared on the main surface 2a. A plurality of first openings 11, a plurality of second openings 12, and a plurality of third openings 13 are formed in the coverlay 5 in advance. A part of the first electrode 3 is exposed from the first opening 11, and a part of the second electrode 4 is exposed from the second opening 12. Further, another part of the first electrode 3, another part of the second electrode 4, and a part of the main surface 2a of the substrate 2 are exposed from the third opening 13.

[0026] Also, as shown in FIG. 3(a), in the first step, some of the plurality of third openings 13 are covered with a mask 21. In some of the third openings 13, a part of the first electrode 3, a part of the second electrode 4, and a part of the main surface 2a of the substrate 2 are completely covered and hidden by the mask 21. In the present embodiment, the third openings 13 exposed from the mask 21 and the third openings 13 covered by the mask 21 are alternately present along the second direction Y. The mask 21 is, for example, a resist mask, a resin member, a masking tape, or the like. The resin constituting the mask 21 is, for example, a polyimide-based resin, a silicone-based resin, an acrylic-based resin, an epoxy-based resin, a urethane-based resin, a fluorine-based resin, a polyolefin-based resin, or the like. The mask 21 is formed by a known method. Hereinafter, the portion of the first electrode 3 exposed from the mask 21 is referred to as a first portion 3a, and the portion of the first electrode covered by the mask 21 is referred to as a second portion 3b. Note that at least a part of the coverlay 5 may be covered by the mask 21. Also, a plurality of masks 21 may be formed on the main surface 2a, or one mask 21 may be formed.

[0027] Next, as shown in FIG. 3(b), a dam material 31 having a plurality of openings 31a is disposed on the main surface 2a (second step). In the second step, the dam material 31 covering the coverlay 5 and the mask 21 is disposed on the main surface 2a. For this reason, the second portion 3b of the first electrode 3 overlaps the dam material 31 at least in the second step. The dam material 31 is, for example, a resin member formed in advance, a resist mask formed on the main surface 2a, or the like. The resin constituting the dam material 31 is, for example, a silicone-based resin, an acrylic-based resin, an epoxy-based resin, a urethane-based resin, a polyimide-based resin, a fluorine-based resin, a polyolefin-based resin, or the like. The dam material 31 is placed on the coverlay 5 or formed by a known method. In the former case, for example, when the dam material 31 is pressed toward the substrate 2, the dam material 31 is adsorbed to the coverlay 5.

[0028] Each opening 31a overlaps any of the third openings 13 not covered by the mask 21. For this reason, also in the second step, in the third opening 13 not covered by the mask 21, a part of the first electrode 3, a part of the second electrode 4, and a part of the main surface 2a of the substrate 2 are exposed. The height H of the dam material 31 along the third direction Z is, for example, 0.5 times or more and 1.3 times or less the length L2 of the short side of the third opening 13 in plan view. When the height H is 0.5 times or more the length L2, the dispersion liquid 41 is less likely to flow out onto the dam material 31 when the dispersion liquid 41 is supplied to the opening 31a described later. Further, when the height H is 1.3 times or less the length L2, the dispersion liquid 41 is less likely to spread onto the coverlay 5 after the dam material 31 described later is removed.

[0029] Next, as shown in FIG. 4(a), a dispersion liquid 41 in which a thermoelectric conversion material is dispersed is supplied to the opening 31a (third step). In the third step, the dispersion liquid 41 is injected into the opening 31a by a known method such as an inkjet method or a dispensing method. As a result, in the third step, the third opening 13 into which the dispersion liquid 41 is injected and the third opening 13 covered by the mask 21 alternately exist along the second direction Y. The dispersion liquid 41 is injected so as to fill at least a part of the opening 31a. The viscosity of the dispersion liquid 41 is not particularly limited. From the viewpoint of suppressing the outflow of the dispersion liquid 41 from the opening 31a, etc., the viscosity of the dispersion liquid 41 at a shear rate of 0.01 s -1 is, for example, 10 4 mPa·sec or more and 10 8 mPa·sec or less. In this case, after the fourth step described later, the dispersion liquid 41 tends to remain well in and around the third opening 13. The viscosity of the dispersion liquid 41 is, for example, a value measured by a rotational rheometer. For example, the viscosity (shear viscosity) is measured using a rheometer ("MCR302" (product name) manufactured by Anton Paar). The measurement conditions are, for example, temperature: 25°C, plate: φ25 mm parallel plate, gap: 1 mm. In the present embodiment, a shear stress is continuously applied to the dispersion liquid 41 at a shear rate of 0.01 / s, and the viscosity value after 10 seconds from the start of the application of the shear stress is taken as the viscosity of the dispersion liquid 41.

[0030] The dispersion liquid 41 used in the third step is, for example, a liquid in which carbon nanotubes and a conductive polymer are dispersed. The content of the carbon nanotubes in the dispersion liquid 41 is, for example, 25% by mass or more, 30% by mass or more, or 35% by mass or more, based on the total amount of the conductive polymer and the carbon nanotubes, and is 95% by mass or less, 90% by mass or less, 85% by mass or less, or 80% by mass or less. In this case, the electrical conductivity of the thermoelectric conversion layer tends to increase. Further, the total mass concentration of the carbon nanotubes and the conductive polymer in the dispersion liquid 41 is, for example, 0.05% by mass or more, 0.06% by mass or more, or 0.07% by mass or more, and is 0.15% by mass or more, 0.12% by mass or more, or 0.10% by mass or more. The total mass concentration of the carbon nanotubes and the conductive polymer in the dispersion liquid 41 may be 1% by mass or less, or may be 0.5% by mass or less. The dispersion liquid 41 used in the third step is, for example, a mixed liquid formed by mixing a first liquid containing carbon nanotubes and a second liquid containing a conductive polymer.

[0031] The first liquid contains, for example, carbon nanotubes and a first solvent. The carbon nanotubes may be single-walled carbon nanotubes or multi-walled carbon nanotubes. The concentration of the carbon nanotubes in the first liquid is, for example, 0.01% by mass or more and 10% by mass or less. The first solvent may be any solvent capable of dispersing carbon nanotubes, and is, for example, a polar liquid or an aqueous solvent. The aqueous solvent is water or a mixed solvent of water and an organic solvent. The first solvent may be a protic solvent or an aprotic solvent. Specific examples of the first solvent are, for example, water, alcohols (such as methanol and ethanol), amides (such as N,N-dimethylformamide, N,N-dimethylacetamide, and N-methylpyrrolidone), ketones (such as acetone and methyl ethyl ketone), glycols (such as ethylene glycol and diethylene glycol), dimethyl sulfoxide, acetonitrile, and the like. Among these, one or more selected from the group consisting of water, methanol, ethanol, N-methylpyrrolidone, and dimethyl sulfoxide are preferable, and water is more preferable. The first liquid may further contain additives such as a surfactant and an organic binder.

[0032] The second liquid contains, for example, a conductive polymer (also referred to as PEDOT / PSS) composed of poly(3,4-ethylenedioxythiophene) (PEDOT) and polystyrene sulfonic acid (PSS), and a second solvent. PEDOT / PSS is a conductive polymer composed of PEDOT and PSS, and can also be referred to as PEDOT doped with PSS. In PEDOT / PSS, the content ratio of PEDOT and PSS is not particularly limited. The ratio (mass ratio) of PSS to PEDOT is, for example, 1 or more, 1.25 or more, or 1.5 or more, and 30 or less, or 20 or less. The second solvent may be any solvent capable of dispersing PEDOT / PSS, and is, for example, a polar liquid or an aqueous solvent. The second solvent may be a protic solvent or an aprotic solvent. Specific examples of the second solvent are the same as the specific examples of the first solvent. One or more of the group consisting of water, methanol, and ethanol are preferable, and water is more preferable. In one aspect, the second liquid may be an aqueous dispersion of PEDOT / PSS. Note that the second solvent may be used alone or in combination of two or more. The second liquid may further contain various additives.

[0033] Next, as shown in FIG. 4(b), the dam material 31 is removed (fourth step). For example, when the dam material 31 is a resin member formed in advance, the dam material 31 is physically removed from above the coverlay 5. For example, when the dam material 31 is a resist mask, the dam material 31 is removed by light, a solvent, or the like. In this case, a solvent or the like that does not affect the dispersion liquid 41 is used. After the removal of the dam material 31, the dispersion liquid 41 remains in and around the third opening 13.

[0034] Next, as shown in FIGS. 5(a), 5(b) and 6(a), the substrate 2 is heated from the main surface 2b side in the third direction Z to form a p-type thermoelectric conversion layer 6 in contact with the first electrode 3 and the second electrode 4 (fifth step). In the fifth step, first, the dispersion liquid 41 is dried by heating the substrate 2 from the main surface 2b side in an air atmosphere. For example, the dispersion liquid 41 is dried by placing the substrate 2 on a hot plate set at 25° C. or higher and 90° C. or lower for 10 minutes or more and 21,600 minutes or less. Thereby, as shown in FIG. 5(a), the residual component 42 of the dispersion liquid 41 is formed on the substrate 2. Subsequently, after the heating of the substrate 2, the mask 21 is removed. The mask 21 is removed physically or chemically, for example. Subsequently, as shown in FIG. 5(b), after the removal of the mask 21, the entire substrate 2 is immersed in dimethyl sulfoxide 51 (immersion treatment). For example, the entire substrate 2 is immersed in dimethyl sulfoxide 51 set at room temperature for 1 minute or more and 7,200 minutes or less. After the immersion treatment, the substrate 2 is heated again from the main surface 2b side. For example, the substrate 2 is heated again by placing the substrate 2 on a hot plate set at 25° C. or higher and 90° C. or lower for 10 minutes or more and 21,600 minutes or less. As a result, as shown in FIG. 6(a), a p-type thermoelectric conversion layer 6 in contact with the first portion 3a of the first electrode 3 is formed. After the fifth step, the third opening 13 provided with the p-type thermoelectric conversion layer 6 and the third opening 13 exposing the substrate 2 and the like are alternately present along the second direction Y. In the fifth step, it is sufficient to heat the substrate 2 at least from the main surface 2b side.

[0035] Next, as shown in FIG. 6(b), an n-type thermoelectric conversion layer 7 having a polarity different from that of the p-type thermoelectric conversion layer 6 is formed (sixth step). In the sixth step, the n-type thermoelectric conversion layer 7 is formed in the third opening 13 where the p-type thermoelectric conversion layer 6 is not provided. Thereby, an n-type thermoelectric conversion layer 7 in contact with the second portion 3b of the first electrode 3 is formed. In the sixth step, for example, the n-type thermoelectric conversion layer 7 is directly formed in the third opening 13, or the previously formed n-type thermoelectric conversion layer 7 adheres to the second portion 3b or the like. In the latter case, the n-type thermoelectric conversion layer 7 may adhere to the second portion 3b or the like via a conductive adhesive, solder, or the like. After the sixth step, the p-type thermoelectric conversion layer 6 and the n-type thermoelectric conversion layer 7 are alternately present along the second direction Y.

[0036] After the sixth step, the thermoelectric conversion module 1 is manufactured by performing steps such as mounting the first terminal 8 and the second terminal 9 on the substrate 2.

[0037] In the manufacturing method of the thermoelectric conversion module 1 according to the present embodiment described above, a dispersion liquid 41 in which a thermoelectric conversion material is dispersed is supplied to the opening 31a of the dam material 31 disposed on the main surface 2a of the substrate 2. Thereby, the dispersion liquid 41 can be selectively supplied to a desired position on the main surface 2a. In addition, in the present embodiment, after removing the dam material 31, the substrate 2 is heated from the main surface 2b side. Thereby, it is possible to prevent the components contained in the dispersion liquid 41 from being fixed to the dam material 31. Therefore, after the fifth step, a p-type thermoelectric conversion layer 6 having a desired shape and a sufficient size can be formed on the main surface 2a. Therefore, an increase in resistance or the like due to the shape of the p-type thermoelectric conversion layer 6 can be suppressed. Therefore, by implementing the manufacturing method according to the present embodiment, a thermoelectric conversion module 1 capable of realizing high output can be provided.

[0038] In addition, according to the configuration of the thermoelectric conversion module 1 according to the present embodiment, each of the p-type thermoelectric conversion layer 6 and the n-type thermoelectric conversion layer 7 can be formed with good yield. Therefore, the performance of each thermoelectric conversion element 100 can be exhibited well. Therefore, the thermoelectric conversion module 1 according to the present embodiment can exhibit high output.

[0039] In the present embodiment, the height H of the dam material 31 may be 0.5 times or more and 2 times or less the length of the short side of the p-type thermoelectric conversion layer 6 in plan view. In this case, when the dispersion liquid 41 is supplied to the opening 31a, the dispersion liquid 41 is less likely to flow out onto the dam material 31. In addition, after removing the dam material 31, the dispersion liquid 41 is less likely to spread onto the coverlay 5. The height H may be 1.5 times or less, or 1.3 times or less the length of the short side.

[0040] In this embodiment, the dispersion liquid 41 contains carbon nanotubes and a conductive polymer composed of poly(3,4-ethylenedioxythiophene) and polystyrene sulfonic acid. The content of the carbon nanotubes may be 25% by mass or more and 95% by mass or less based on the total amount of the conductive polymer and the carbon nanotubes. In this case, since the voids between the carbon nanotubes in the p-type thermoelectric conversion layer 6 tend to be well filled with the conductive polymer, the p-type thermoelectric conversion layer 6 can be made to have a lower resistance.

[0041] In this embodiment, the total mass concentration of the carbon nanotubes and the conductive polymer in the dispersion liquid 41 may be 0.05% by mass or more. The total mass concentration of the carbon nanotubes and the conductive polymer in the dispersion liquid 41 may be 1% by mass or less, and may be 0.5% by mass or less. In this case, since the viscosity of the dispersion liquid 41 increases, it becomes difficult to spread on the coverlay 5. For this reason, since the obtained p-type thermoelectric conversion layer 6 can be formed thickly, the electrical resistance of the p-type thermoelectric conversion layer 6 can be lowered.

[0042] In this embodiment, at a shear rate of 0.01 s -1 the viscosity of the dispersion liquid 41 may be 10 4 mPa·sec or more and 10 8 mPa·sec or less. In this case, after the fourth step, the dispersion liquid 41 tends to remain well inside and around the third opening 13.

[0043] In this embodiment, in the fifth step, the substrate may be heated at 25°C or more and 90°C or less. In this case, the dispersion liquid 41 can be dried while suppressing breakage of the substrate 2 and the coverlay 5.

[0044] In this embodiment, in the fifth step, the substrate 2 may be heated in an air atmosphere. In this case, the dispersion liquid 41 can be dried inexpensively and easily.

[0045] In this embodiment, the manufacturing method includes a sixth step of forming an n-type thermoelectric conversion layer 7 having a polarity different from that of the p-type thermoelectric conversion layer 6. The first electrode 3 has a first portion 3a in contact with the p-type thermoelectric conversion layer 6 and a second portion 3b in contact with the n-type thermoelectric conversion layer 7. In the second and third steps, the second portion 3b may overlap the dam material 31. In this case, it is possible to preferably prevent the p-type thermoelectric conversion layer 6 from being formed in the portion where the n-type thermoelectric conversion layer 7 is formed on the main surface 2a.

[0046] In this embodiment, in the first step, the second portion 3b is covered with the mask 21, and in the fifth step, the mask 21 may be removed after heating the substrate 2. In this case, it is possible to more preferably prevent the p-type thermoelectric conversion layer 6 from being formed in the portion where the n-type thermoelectric conversion layer 7 is formed on the main surface 2a.

[0047] The manufacturing method of the thermoelectric conversion module according to one aspect of the present invention is not limited to the above embodiment, and various other modifications are possible. For example, in the first step, some of the plurality of third openings are covered with a mask, but it is not limited thereto.

[0048] In addition, the thermoelectric conversion material included in the n-type thermoelectric conversion layer may include carbon nanotubes. In this case, the n-type thermoelectric conversion layer has a dopant in addition to, for example, the carbon nanotubes and the conductive polymer of the p-type thermoelectric conversion layer. When forming such an n-type thermoelectric conversion layer, a thermoelectric conversion module can be manufactured without using a mask. Here, the dopant is intended to be a substance that changes the Seebeck coefficient of the material to be doped with the dopant. "Changing the Seebeck coefficient" is intended to mean decreasing the value of the Seebeck coefficient or changing the value of the Seebeck coefficient from a positive value to a negative value. The dopant contains, for example, an anion which is a complex ion (hereinafter also simply referred to as "anion"), an alkali metal cation (hereinafter also simply referred to as "cation"), and a cation scavenger (hereinafter also simply referred to as "scavenger"). The dopant may contain a plurality of types of anions, cations, and scavengers, respectively. In this case, the thermal conductivity and thermal diffusivity of the n-type thermoelectric conversion layer can be obtained in the same manner as, for example, the p-type thermoelectric conversion layer.

[0049] The anion which is a complex ion may be an anion selected from the group consisting of ferrocyanide ion, ferricyanide ion, tetrachloroferrate(III) ion, tetrachloroferrate(II) ion, tetracyanonickelate(II) ion, tetrachloronickelate(II) ion, tetracyanocobalt(II) ion, tetrachlorocobaltate(II) ion, tetracyanocuprate(I) ion, tetrachlorocuprate(II) ion, hexacyanochromium(III) ion, tetrahydroxozincate(II) ion, and tetrahydroxoaluminate(III) ion. The anion may be an anion generated by dissociation of the complex salt in the dopant solution. Examples of the complex salt include potassium ferrocyanide, sodium ferrocyanide, potassium ferricyanide, sodium ferricyanide, potassium tetrachloroferrate(III), sodium tetrachloroferrate(III), potassium tetrachloroferrate(II), and sodium tetrachloroferrate(II). The complex salt may be a hydrate. Since the anion is a complex ion, metal atoms derived from the complex ion remain in the n-type thermoelectric conversion layer. As a result, the metal atoms remaining in the n-type thermoelectric conversion layer function as an antioxidant, suppressing physical property changes over time and improving storage stability.

[0050] Examples of the alkali metal cation include sodium ion, potassium ion, and lithium ion. The cation scavenger is not particularly limited as long as it is a substance having the ability to capture cations. Examples thereof include crown ether compounds, cyclodextrin, calixarene, ethylenediaminetetraacetic acid, porphyrin, phthalocyanine, and their derivatives. In an organic solvent, it is preferable to use a crown ether compound.

Example

[0051] One aspect of the present invention will be described in more detail by the following examples, but one aspect of the present invention is not limited to these examples.

[0052] (Example 1) <Dispersion liquid> 0.28 g of a PEDOT / PSS aqueous dispersion (manufactured by Heraeus Corporation, "Clevious (registered trademark) PH1000", solid content concentration: 1.2% by mass) and 5 g of a carbon nanotube dispersion (concentration: 0.2% by mass, G / D ratio: 28.5) were thoroughly stirred using a planetary mixer (manufactured by Shinki Corporation, "Awatori Rentaro ARE-310"). As a result, a dispersion was prepared in which the content of carbon nanotubes was 75% by mass based on the total amount of PEDOT / PSS and carbon nanotubes. The concentration of the dispersion at a shear rate of 0.01 s -1 was 301630 mPa·sec. The viscosity of the dispersion was measured using a rheometer (manufactured by Anton Paar, "MCR302" (product name)). The measurement conditions were: temperature: 25°C, plate: φ25 mm parallel plate, gap: 1 mm.

[0053] <Substrate for module> A flexible substrate 60 for a module shown in FIG. 7 was prepared. The substrate 60 for a module has a polyimide substrate 2 (thickness: 25 μm, thermal conductivity: 0.3 W / mK) having a rectangular main surface 2a with a short side: 20 mm and a long side: 100 mm. On the main surface 2a of the substrate 2, a plurality of first electrodes 3 and a plurality of second electrodes 4 (thickness: 12 μm) and a coverlay 5 (made of polyimide resin, thickness: 60 μm, thermal conductivity: 0.3 W / mK) are provided. Each of the first electrode 3 and the second electrode 4 has a copper layer portion, a nickel-plated portion covering the copper layer portion, and a gold-plated portion covering the nickel-plated portion. The coverlay 5 has a plurality of first openings 11, a plurality of second openings 12, and a plurality of third openings 13. A total of 13 third openings 13 are provided in the substrate 60 for a module. When viewed from the thickness direction of the substrate 60 for a module, the length of the third opening 13 along the long side direction of the main surface 2a is 5 mm, and the length of the third opening 13 along the short side direction of the main surface 2a is 6 mm. Also, each of a part of the first electrode 3 exposed at the third opening 13 and a part of the second electrode 4 exposed at the third opening 13 has the same shape. The length of the above-mentioned part of the first electrode 3 along the long side direction is 5 mm, and the length of the above-mentioned part of the first electrode 3 along the short side direction is 2 mm.

[0054] <Thermoelectric conversion module> First, the substrate 60 for the module was cleaned with acetone. Next, a part of the plurality of third openings 13 was filled with masking tape (manufactured by 3M Japan Limited, "Heat-resistant polyimide tape 7414"). Some of the third openings 13 were filled with masking tape so that the third openings 13 filled with the masking tape and the third openings 13 not filled with the masking tape alternately existed along the long side direction of the main surface 2a. The third opening 13 located at the most one end side in the long side direction and the third opening 13 located at the most other end side in the long side direction were not filled with the masking tape.

[0055] Next, a dam material in the shape of a rectangular parallelepiped made of silicone rubber, with a short side: 20 mm, a long side: 100 mm, and a thickness: 4 mm, was placed on the substrate 60 for the module. Subsequently, the dam material was pressed against the substrate 60 for the module, and the dam material was bonded to the substrate 60 for the module. The dam material is provided with a plurality of openings extending along the thickness direction. Each of the plurality of openings has the same shape as the third opening 13 when viewed from the thickness direction of the dam material. Each opening overlaps with one of the third openings 13. Therefore, after the dam material is placed on the substrate 60 for the module, the third opening 13 not covered with the masking tape and the masking tape are exposed from the dam material.

[0056] Next, among the plurality of openings provided in the dam material, the dispersion liquid described above was injected into the opening that exposes the third opening 13 not covered with the masking tape. Here, 0.12 ml of the dispersion liquid was injected per location. After the injection of the dispersion liquid, the dam material was gently removed from the substrate 60 for the module. Subsequently, the substrate 60 for the module was placed on a hot plate set at 60°C for 180 minutes. Thereby, the dispersion liquid was dried. Subsequently, the masking tape was removed from the substrate 60 for the module.

[0057] Next, the entire substrate 60 for the module was immersed in room-temperature DMSO (manufactured by Fujifilm Wako Pure Chemical Corporation) for 5 minutes. Subsequently, the substrate 60 for the module taken out from the DMSO was placed on a hot plate set at 60°C for 60 minutes. As a result, a p-type thermoelectric conversion layer (thickness: 5 μm) was formed in a total of seven third openings 13.

[0058] Next, a plurality of nickel pieces (short side: 3 mm, long side: 6 mm) were formed from a nickel foil (thickness: 10 μm). Subsequently, the nickel pieces were joined by soldering to the first electrode 3 and the second electrode 4 exposed at the third opening 13 where the p-type thermoelectric conversion layer was not formed. As a result, an n-type thermoelectric conversion layer (thickness: 10 μm) was formed in a total of six third openings 13. Thus, a thermoelectric conversion module in which the p-type thermoelectric conversion layer and the n-type thermoelectric conversion layer are alternately arranged in the long-side direction of the main surface 2a was formed.

[0059] (Example 2) A thermoelectric conversion module was formed in the same manner as in Example 1, except that the thickness of the dam material was 3 mm and the injection amount of the dispersion per location was 0.09 ml.

[0060] (Example 3) A thermoelectric conversion module was formed in the same manner as in Example 1, except that the thickness of the dam material was 6 mm and the injection amount of the dispersion per location was 0.18 ml.

[0061] (Comparative Example 1) A thermoelectric conversion module was formed in the same manner as in Example 1, except that no dam material was used.

[0062] (Comparative Example 2) Up to the step of injecting the dispersion liquid into the opening of the dam material, the same procedure as in Example 1 was carried out. Subsequently, without removing the dam material, the substrate 60 for the module was placed on a hot plate set at 60 °C for 180 minutes. Subsequently, when the dam material was removed from the substrate 60 for the module, the residual components of the dispersion liquid were peeled off from the substrate 60 for the module together with the dam material. For this reason, in Comparative Example 2, a thermoelectric conversion module could not be obtained.

[0063] (Evaluation of Thermoelectric Conversion Module) One side of the thermoelectric conversion modules of Examples 1 to 3 and Comparative Example 1 was brought into contact with a hot plate at 50 °C. In addition, the other side of each thermoelectric conversion module was brought into contact with a hose through which a refrigerant at 10 °C circulated. Thereby, a temperature difference was generated in each thermoelectric conversion layer. Then, the maximum output and resistance value of each thermoelectric conversion module were evaluated using a source meter ("Keithley 2612B" manufactured by Tektronix). Table 1 below shows the evaluation results of Examples 1 to 3 when the maximum output and resistance value of the thermoelectric conversion module of Comparative Example 1 were set to 100. One side of the thermoelectric conversion module corresponds to one end side in the short side direction of the main surface 2a, and the other side of the thermoelectric conversion module corresponds to the other end side in the short side direction of the main surface 2a.

[0064]

Table 1

Explanation of Reference Numerals

[0065] 1... Thermoelectric conversion module, 2... Substrate, 2a... Main surface (first main surface), 2b... Main surface (second main surface), 3... First electrode, 3a... First part, 3b... Second part, 4... Second electrode, 5... Coverlay, 6... p-type thermoelectric conversion layer (thermoelectric conversion layer), 7... n-type thermoelectric conversion layer (another thermoelectric conversion layer), 11... First opening, 12... Second opening, 13... Third opening, 21... Mask, 31... Dam material, 31a... Opening, 41... Dispersion liquid, 60... Substrate for module, 100... Thermoelectric conversion element, S1 to S3... Gap.

Claims

1. A first step of preparing a substrate having a first main surface on which a first electrode and a second electrode spaced apart from each other are disposed; A second step of disposing a dam material having an opening on the first main surface; A third step of supplying a dispersion liquid in which a thermoelectric conversion material is dispersed to the opening; A fourth step of removing the dam material; A fifth step of heating the substrate from the second main surface side located on the opposite side of the first main surface in the thickness direction of the substrate to form a thermoelectric conversion layer in contact with the first electrode and the second electrode; A sixth step of forming another thermoelectric conversion layer having a polarity different from that of the thermoelectric conversion layer; Comprising in order, The first electrode has a first portion in contact with the thermoelectric conversion layer and a second portion in contact with the another thermoelectric conversion layer, In the second step and the third step, the second portion overlaps the dam material, In the first step, the second portion is covered with a mask, In the fifth step, the mask is removed after heating the substrate, A method for manufacturing a thermoelectric conversion module.

2. The height of the dam material is 0.5 times or more and 2 times or less the length of the short side of the thermoelectric conversion layer in plan view. The manufacturing method according to Claim 1.

3. The thermoelectric conversion material includes carbon nanotubes and a conductive polymer composed of poly(3,4-ethylenedioxythiophene) and polystyrenesulfonic acid, The content of the carbon nanotubes is 25% by mass or more and 95% by mass or less based on the total amount of the conductive polymer and the carbon nanotubes. The manufacturing method according to Claim 1 or 2.

4. The total mass concentration of the carbon nanotubes and the conductive polymer in the dispersion liquid is 0.05% by mass or more. The manufacturing method according to Claim 3.

5. Shearing speed: 0.01 s －１ The viscosity of the dispersion liquid at this time is 10 ４ mPa·sec or more and 10 ８ mPa·sec or less. The manufacturing method according to any one of claims 1 to 4

6. In the fifth step, the substrate is heated at 25°C or more and 90°C or less. The manufacturing method according to any one of Claims 1 to 5.

7. In the fifth step, the substrate is heated in an air atmosphere. The manufacturing method according to any one of Claims 1 to 6.

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