WO2024075821A1 - Composition pour éléments de conversion thermoélectrique, module de conversion thermoélectrique, procédé de production de composition pour éléments de conversion thermoélectrique, et procédé de production de module de conversion thermoélectrique - Google Patents

Composition pour éléments de conversion thermoélectrique, module de conversion thermoélectrique, procédé de production de composition pour éléments de conversion thermoélectrique, et procédé de production de module de conversion thermoélectrique Download PDF

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Publication number
WO2024075821A1
WO2024075821A1 PCT/JP2023/036445 JP2023036445W WO2024075821A1 WO 2024075821 A1 WO2024075821 A1 WO 2024075821A1 JP 2023036445 W JP2023036445 W JP 2023036445W WO 2024075821 A1 WO2024075821 A1 WO 2024075821A1
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WIPO (PCT)
Prior art keywords
thermoelectric conversion
composition
nanocarbon
type thermoelectric
conversion element
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PCT/JP2023/036445
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English (en)
Japanese (ja)
Inventor
司 松浦
静 都築
海音 堂坂
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株式会社東海理化電機製作所
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Publication of WO2024075821A1 publication Critical patent/WO2024075821A1/fr

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    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/01—Manufacture or treatment
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/10—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects
    • H10N10/17—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects operating with only the Peltier or Seebeck effects characterised by the structure or configuration of the cell or thermocouple forming the device
    • H—ELECTRICITY
    • H10—SEMICONDUCTOR DEVICES; ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N—ELECTRIC SOLID-STATE DEVICES NOT OTHERWISE PROVIDED FOR
    • H10N10/00—Thermoelectric devices comprising a junction of dissimilar materials, i.e. devices exhibiting Seebeck or Peltier effects
    • H10N10/80—Constructional details
    • H10N10/85—Thermoelectric active materials
    • H10N10/851—Thermoelectric active materials comprising inorganic compositions
    • H10N10/855—Thermoelectric active materials comprising inorganic compositions comprising compounds containing boron, carbon, oxygen or nitrogen

Definitions

  • thermoelectric conversion module uses the same, a method for producing a composition for a thermoelectric conversion element, and a method for producing a thermoelectric conversion module.
  • thermoelectric elements 24 made of multiple cylindrical BiTe-based single crystals are sandwiched between first and second flexible printed circuit boards 32, 33. Wiring layers 35, 36 that connect the thermoelectric elements 24 are formed on the first and second flexible printed circuit boards 32, 33, respectively.
  • the thermoelectric elements 24 are made of p-type thermoelectric elements 24a and n-type thermoelectric elements 24b, which are alternately connected in series by the wiring layers 35, 36.
  • the p-type thermoelectric elements 24a are made of, for example, BiSbTe chips
  • the n-type thermoelectric elements 24b are made of, for example, BiTe chips (paragraphs [0027] to [0030]).
  • thermoelectric power generation module 10 disclosed in WO 2021/220533, as shown in FIG. 2 of WO 2021/220533, a p-type thermoelectric element 24a and an n-type thermoelectric element 24b are embedded in a cylindrical hole formed in a resin thin film 21.
  • the p-type thermoelectric element 24a formed from a BiSbTe chip and the n-type thermoelectric element 24b formed from a BiTe chip are metallic bulk elements and therefore brittle and easily broken. Therefore, there is a problem that it is difficult to handle when mounting the thermoelectric element on the resin thin film 21.
  • bismuth tellurium-based materials are toxic and have poor mechanical strength.
  • the present disclosure aims to obtain a composition for thermoelectric conversion elements that is easy to embed thermoelectric conversion element materials, and to obtain a thermoelectric conversion module that includes a thermoelectric conversion element formed from the composition for thermoelectric conversion elements that is easy to embed.
  • thermoelectric conversion element composition of the first embodiment is a thermoelectric conversion element composition having flowability, and includes nanocarbon, a dopant that imparts p-type semiconductor properties to the nanocarbon, and a binder resin.
  • the composition for thermoelectric conversion elements is a composite material containing nanocarbon and a binder resin, it can have a fluidity such as a paste or ink. Therefore, the handling property of the composition can be improved, such as making it easier to fill through holes formed in a substrate.
  • nanocarbon is used as a p-type semiconductor material, the use of toxic materials (Bi, Te, Se, Pb, etc.) can be avoided.
  • nanocarbon includes carbon nanotubes and graphene.
  • thermoelectric conversion element composition of the second embodiment is a thermoelectric conversion element composition having flowability, and includes nanocarbon, a dopant that imparts n-type semiconductor properties to the nanocarbon, and a binder resin.
  • the composition for thermoelectric conversion elements is a composite material containing nanocarbon and binder resin, and can have a paste-like, ink-like, or other fluidity. This improves the handling properties of the composition, such as making it easier to fill through-holes formed in a substrate.
  • nanocarbon is used as the n-type semiconductor material, the use of toxic materials (Bi, Te, Se, Pb, etc.) can be avoided.
  • the mechanical strength of the formed thermoelectric conversion element can be improved.
  • thermoelectric conversion element composition of the third embodiment is a thermoelectric conversion element composition of the first or second embodiment that does not contain a surfactant.
  • thermoelectric conversion element composition that does not contain a surfactant
  • nanocarbon particles can be more closely bonded due to their cohesiveness. Furthermore, since no surfactant with low electrical conductivity is present between the nanocarbon particles, the electrical conductivity of the thermoelectric conversion element formed from the thermoelectric conversion element composition can be improved.
  • does not contain a surfactant refers to a case where no surfactant is contained at all, or a case where a trace amount of a surfactant is contained, as long as the effect of the invention can be obtained to the same extent as when no surfactant is contained at all.
  • the thermoelectric conversion module of the fourth aspect includes a substrate having a plurality of through holes formed therein, p-type thermoelectric conversion elements mounted in the plurality of through holes, n-type thermoelectric conversion elements mounted and filled in the plurality of through holes, and a conductive material that alternately connects the p-type thermoelectric conversion elements and the n-type thermoelectric conversion elements in series.
  • the p-type thermoelectric conversion elements are formed from a composition for p-type thermoelectric conversion elements that includes nanocarbon, a dopant that imparts p-type semiconductor properties to the nanocarbon, and a binder resin.
  • the n-type thermoelectric conversion elements are formed from a composition for n-type thermoelectric conversion elements that includes nanocarbon, a dopant that imparts n-type semiconductor properties to the nanocarbon, and a binder resin.
  • thermoelectric conversion element in the thermoelectric conversion module is made of a composite material of nanocarbon and binder resin, so the thermal conductivity can be reduced without lowering the Seebeck coefficient. As a result, the performance of the thermoelectric conversion element can be improved. In addition, because the thermoelectric conversion element is made of a composite material of nanocarbon and binder resin, the adhesion to the substrate can be improved.
  • the thermoelectric conversion module of the fifth aspect includes a substrate having a plurality of through holes and a plurality of via holes, either a p-type thermoelectric conversion element or an n-type thermoelectric conversion element mounted in the plurality of through holes, and a conductive material that alternately connects the p-type thermoelectric conversion element or the n-type thermoelectric conversion element and the via holes in series.
  • the p-type thermoelectric conversion element is formed from a composition for p-type thermoelectric conversion elements that includes nanocarbon, a dopant that imparts p-type semiconductor properties to the nanocarbon, and a binder resin.
  • the n-type thermoelectric conversion element is formed from a composition for n-type thermoelectric conversion elements that includes nanocarbon, a dopant that imparts n-type semiconductor properties to the nanocarbon, and a binder resin.
  • thermoelectric conversion module In a thermoelectric conversion module, the hole diameter of the via hole is extremely small compared to the hole diameter of the through hole in which the p-type thermoelectric conversion element or n-type thermoelectric conversion element is filled, so the thermoelectric conversion module can have via holes without reducing the number of thermoelectric conversion elements.
  • thermoelectric conversion module is the thermoelectric conversion module of the fourth or fifth aspect, in which the substrate is a printed circuit board.
  • thermoelectric conversion module is constructed by mounting a thermoelectric conversion element on a printed circuit board. Therefore, the printed circuit board itself functions as a thermoelectric conversion module, and the printed circuit board itself can heat, cool, or generate electricity.
  • thermoelectric conversion module is the thermoelectric conversion module of the sixth aspect, in which the printed circuit board is a rigid board.
  • Thermoelectric conversion module is constructed by mounting thermoelectric conversion elements on a rigid substrate. This allows the aspect ratio of the thermoelectric conversion elements to be increased and allows the thermoelectric conversion elements to be mounted at high density.
  • thermoelectric conversion module of the eighth aspect is a thermoelectric conversion module of any one of the fourth to seventh aspects, in which the through hole is a non-through hole.
  • Thermoelectric conversion module has non-through holes, which prevents electricity from flowing through the inner walls of the holes.
  • thermoelectric conversion module is a thermoelectric conversion module according to any one of the fourth to eighth aspects, in which the binder resin and the substrate contain the same resin.
  • Thermoelectric conversion module allows the linear expansion coefficients of the thermoelectric conversion element and the substrate to be close to each other by containing the same resin in the binder resin and substrate. This makes it possible to prevent the thermoelectric conversion element from peeling off from the substrate due to thermal contraction of the resin caused by temperature changes such as heating.
  • the tenth aspect of the method for producing a composition for thermoelectric conversion elements includes a preparation step of dispersing nanocarbon in a solvent to prepare a nanocarbon dispersion, an addition step of adding either a p-type dopant or an n-type dopant to the nanocarbon dispersion, and a substitution step of adding a binder resin while removing the solvent from the nanocarbon dispersion to substitute the binder resin for the solvent.
  • thermoelectric conversion element composition makes it possible to obtain a thermoelectric conversion element composition having fluidity.
  • the manufacturing method of the thermoelectric conversion module of the eleventh aspect includes a preparation step of preparing a substrate having a plurality of through holes formed therein, a filling step of filling some of the plurality of through holes with a composition for p-type thermoelectric conversion elements and filling through holes not filled with the composition for p-type thermoelectric conversion elements with a composition for n-type thermoelectric conversion elements, a formation step of forming a p-type thermoelectric conversion element from the composition for p-type thermoelectric conversion elements and an n-type thermoelectric conversion element from the composition for n-type thermoelectric conversion elements, and a connection step of alternately connecting the p-type thermoelectric conversion elements and the n-type thermoelectric conversion elements in series using a conductive material.
  • the composition for p-type thermoelectric conversion elements includes nanocarbon, a dopant that imparts p-type semiconductor properties to the nanocarbon, and a binder resin.
  • the composition for n-type thermoelectric conversion elements includes nanocarbon, a dopant that imparts n-type semiconductor properties to the nanocarbon, and a binder resin.
  • thermoelectric conversion modules makes it possible to obtain high power generation, high heating performance, and high cooling performance.
  • the thermoelectric conversion module of the twelfth aspect includes a preparation step of preparing a substrate having a plurality of through holes and a plurality of via holes formed therein, a filling step of filling the plurality of through holes with either a composition for p-type thermoelectric conversion elements or a composition for n-type thermoelectric conversion elements, a formation step of forming a p-type thermoelectric conversion element or an n-type thermoelectric conversion element from the composition for p-type thermoelectric conversion elements or the composition for n-type thermoelectric conversion elements, and a connection step of alternately connecting the p-type thermoelectric conversion elements or the n-type thermoelectric conversion elements and the via holes in series using a conductive material.
  • the composition for p-type thermoelectric conversion elements includes nanocarbon, a dopant that imparts p-type semiconductor properties to the nanocarbon, and a binder resin.
  • the composition for n-type thermoelectric conversion elements includes nanocarbon, a dopant that imparts n-type semiconductor properties to the nanocarbon, and a binder resin.
  • thermoelectric conversion module can reduce the number of manufacturing steps for the thermoelectric conversion module because it is only necessary to fill either the composition for a p-type thermoelectric conversion element or the composition for an n-type thermoelectric conversion element. In addition, the number of materials used can be reduced, leading to cost savings.
  • the composition for thermoelectric conversion elements is one in which nanocarbon, to which p-type or n-type semiconductor properties have been imparted, is dispersed in a binder resin, and therefore has fluidity and can be easily embedded in a substrate.
  • nanocarbon which is a semiconductor material, is not toxic.
  • a thermoelectric conversion element formed from a composition for thermoelectric conversion elements containing nanocarbon and a binder resin can have improved mechanical strength.
  • FIG. 1 is a diagram illustrating an example of the upper surface of a thermoelectric conversion module 10 according to an embodiment, in which a p-type thermoelectric conversion element 21 and an n-type thermoelectric conversion element 22 formed from a composition for thermoelectric conversion elements are mounted.
  • Wiring 31 is formed at the position indicated by the dotted line in FIG. 1, and this is a cross-sectional view showing a cut surface when cut along line AB.
  • FIG. 2 is a diagram illustrating an example of the upper surface of a thermoelectric conversion module 20 according to an embodiment, in which only a p-type thermoelectric conversion element 21 formed from a composition for thermoelectric conversion elements is mounted.
  • 4 is a cross-sectional view showing a cut surface when wiring 31 is formed at the position shown by the dotted line in FIG.
  • FIG. 1 is a graph in which compositions for thermoelectric conversion elements having different viscosities of binder resins are plotted with the carbon nanotube content on the horizontal axis and the electrical resistivity on the vertical axis.
  • FIG. 1 is a diagram showing the bulk shape produced in the examples.
  • thermoelectric conversion element composition for forming a thermoelectric conversion element is adjusted so as to be easily filled into through holes (also called holes) formed in a substrate.
  • the thermoelectric conversion element composition contains p-type or n-type doped nanocarbon as a semiconductor material, and the doped nanocarbon is dispersed in a binder resin. Therefore, the thermoelectric conversion element composition has fluidity and is soft, making it easy to fill holes.
  • ZT a dimensionless figure of merit ZT, which is one of the indices for evaluating the thermoelectric conversion performance of a thermoelectric conversion element.
  • ZT is expressed by the following formula (1).
  • Dimensionless figure of merit ZT S2 x ⁇ x T/ ⁇ (1)
  • S (V/K) represents the Seebeck coefficient
  • ⁇ (S/m) represents the electrical conductivity
  • ⁇ (W/mK) represents the thermal conductivity
  • T (K) the absolute temperature.
  • thermoelectric conversion element formed from a composition for thermoelectric conversion elements has a high electrical conductivity ( ⁇ ) due to the nanocarbon, while the thermal conductivity ( ⁇ ) can be reduced by the binder resin, and as a result, the dimensionless figure of merit (ZT) can be increased.
  • ⁇ electrical conductivity
  • ZT dimensionless figure of merit
  • thermoelectric conversion element composition according to a first embodiment of the present disclosure is a flowable composition for thermoelectric conversion elements, and includes nanocarbon, a dopant that imparts p-type semiconductor properties to the nanocarbon, and a binder resin.
  • a thermoelectric conversion element composition according to a second embodiment of the present disclosure is a flowable composition for thermoelectric conversion elements, and includes nanocarbon, a dopant that imparts n-type semiconductor properties to the nanocarbon, and a binder resin.
  • the content of nanocarbon in the composition for thermoelectric conversion elements may be 0.2 wt% or more, assuming that the total amount of binder resin and nanocarbon is 100 wt%. Preferably, it is 0.2 wt% to 0.75 wt%.
  • the nanocarbon may be a carbon nanotube (CNT).
  • the carbon nanotube may be a single-walled carbon nanotube (SWCNT) in which one carbon film (graphene sheet) is wound into a cylindrical shape.
  • the carbon nanotube may be a double-walled carbon nanotube in which two graphene sheets are wound concentrically, or a multi-walled carbon nanotube (MWCNT) such as a triple-walled carbon nanotube or a quadruple-walled carbon nanotube.
  • MWCNT multi-walled carbon nanotube
  • the carbon nanotube is preferably 10 layers or less.
  • Single-walled carbon nanotubes are preferred because they tend to provide high thermoelectric properties.
  • Multi-walled carbon nanotubes are preferred because they are inexpensive and have excellent mass productivity.
  • Single-walled carbon nanotubes and multi-walled carbon nanotubes can also be used in combination.
  • the carbon nanotubes may be metallic carbon nanotubes, semiconducting carbon nanotubes, or a mixture of the two.
  • Carbon nanotubes can be produced by arc discharge, chemical vapor deposition (CVD), laser ablation, etc. Commercially available carbon nanotubes may also be used.
  • the nanocarbon may be graphene.
  • the graphene By placing a carrier between two layers of graphene, the graphene can be used as a semiconductor material.
  • the dopant is not particularly limited as long as it is a dopant that imparts a semiconductor function to the nanocarbon in the composition for thermoelectric conversion elements, and examples thereof include onium salts (onium compounds).
  • the dopant that imparts the function of a p-type semiconductor can be the following:
  • a single-walled carbon nanotube may be used without using a dopant.
  • the dopant that imparts the function of an n-type semiconductor can be listed as follows:
  • an epoxy resin may be used as the binder resin, and no dopant may be used.
  • the amount of dopant is not particularly limited as long as it imparts the nanocarbon with the functionality of a p-type or n-type semiconductor.
  • S Seebeck coefficient
  • ⁇ electrical conductivity
  • the binder resin may be a thermosetting resin or a thermoplastic resin.
  • a thermosetting resin that can withstand the heat applied when mounting electronic components on the printed circuit board is preferred.
  • thermosetting resins include epoxy resin, acrylic resin, polyimide resin, etc.
  • the amount of binder resin is not particularly limited as long as the thermoelectric conversion element composition can maintain the fluidity of a paste or ink and can ensure the desired electrical conductivity.
  • the composition for thermoelectric conversion elements may contain a surfactant.
  • a surfactant for example, in a nanocarbon dispersion, nanocarbon (carbon nanotubes or graphene) is generally dispersed in a solvent containing a surfactant-type dispersant. The surfactant adheres to the surface of the nanocarbon and prevents the nanocarbon from agglomerating. In this way, when a commercially available nanocarbon dispersion is used, a surfactant adheres to the surface of the nanocarbon, and the surfactant can improve the dispersibility of the nanocarbon in the composition for thermoelectric conversion elements.
  • surfactants include known surfactants (such as cationic surfactants and anionic surfactants).
  • thermoelectric conversion element composition does not need to contain a surfactant. If a thermoelectric conversion element composition that does not contain a surfactant is used, that is, if nanocarbon that does not have a surfactant attached to its surface is used, it is possible to obtain nanocarbon that is more closely connected due to the cohesiveness of the nanocarbon. In addition, it is possible to avoid the presence of a surfactant with low electrical conductivity between the nanocarbon.
  • thermoelectric conversion element composition may contain a thixotropic agent, an antioxidant, a weather-resistant light stabilizer, a heat stabilizer, a plasticizer, etc., as appropriate.
  • the viscosity of the thermoelectric conversion element composition can be controlled by the viscosity of the binder resin used.
  • the viscosity of the thermoelectric conversion element composition there are no particular limitations on the viscosity of the thermoelectric conversion element composition.
  • the viscosity of the binder resin may be 10,000 mPa ⁇ s or less. Preferably, it is 2,000 mPa ⁇ s to 5,000 mPa ⁇ s.
  • thermoelectric conversion module 10 A thermoelectric conversion module 10 according to a third embodiment of the present disclosure will be described with reference to FIGS. 1 and 2.
  • FIG. 1 is a diagram illustrating the upper surface of the thermoelectric conversion module 10 in a state in which a p-type thermoelectric conversion element 21 and an n-type thermoelectric conversion element 22 formed from a composition for thermoelectric conversion elements are mounted.
  • FIG. 2 is a cross-sectional view showing a cut surface when wiring 31 is formed at the position indicated by the dotted line in FIG. 1 and cut along line A-B in FIG. 1.
  • the p-type thermoelectric conversion element 21 and the n-type thermoelectric conversion element 22 are mounted in through holes formed in a substrate 11.
  • the p-type thermoelectric conversion element 21 and the n-type thermoelectric conversion element 22 are alternately wired in series and electrically connected as shown in FIG. 2. Note that in FIG. 1, the position (31) where the wiring 31 is formed on the upper surface is indicated by a dotted line. Furthermore, the substrate 11 may be provided with an extraction electrode 41.
  • the p-type thermoelectric conversion element 21 and the n-type thermoelectric conversion element 22 are formed from the composition for thermoelectric conversion elements described above.
  • the substrate 11 can be, for example, a printed circuit board.
  • a printed circuit board When a printed circuit board is used, the printed circuit board itself can be used as a thermoelectric conversion module. Furthermore, the use of a printed circuit board makes it easier to connect to the outside, and a control circuit can be formed on the same substrate as needed.
  • the printed circuit board may be a flexible substrate or a rigid substrate.
  • a rigid substrate is preferable because it allows thermoelectric conversion elements to be mounted at a higher density.
  • the use of a rigid substrate allows soldering and electronic components to be mounted, so that the control circuit can be formed on the same surface. In this way, a thermoelectric conversion module can be formed in part of the ECU (Electronic Control Unit), forming a mechanism for directly cooling the area directly below the heat-generating component.
  • ECU Electronic Control Unit
  • thermoelectric conversion element composition is an epoxy resin
  • the linear expansion coefficients of the substrate and the binder resin can be made close to each other, so that the thermoelectric conversion element can be prevented from peeling off from the substrate due to thermal contraction of the resin.
  • plastic films include polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polybutylene terephthalate, poly(1,4-cyclohexylene dimethylene terephthalate), polyethylene-2,6-naphthalenedicarboxylate, polyester films such as polyester films of bisphenol A and iso- and terephthalic acid, polycarbonate films, polyether ether ketone films, polyphenyl sulfide films, etc.
  • the thickness of the substrate may be 0.1 mm to 6.5 mm.
  • the gap between the through holes formed in the substrate may be 0.1 mm to 3.0 mm.
  • the shape of the through holes may be a round hole, a rectangular hole (square hole), an elongated round hole (rectangle with rounded corners), an oblong hole (rectangle hole), or the like.
  • the holes may be polygonal. From the viewpoint of easiness of filling uniformly without gaps, a round hole, i.e., a cylindrical shape, is preferable.
  • the hole diameter ( ⁇ ) may be 0.3 mm to 5.0 mm. It is preferably 0.5 mm to 2.0 mm, and more preferably 1 mm to 1.5 mm.
  • the length of one side may be 0.3 mm to 5.0 mm, and in the case of an elongated round hole (rectangle with rounded corners) or an oblong hole (rectangle hole), the average length of two sides may be 0.3 mm to 5.0 mm. If the through holes are too narrow, there is a high possibility of Joule heat being generated, and conversely, if they are too wide, there is a possibility that a sufficient number of thermoelectric conversion elements may not be secured.
  • the through holes can be arranged, for example, in a staggered or parallel arrangement.
  • Figure 1 shows an example in which the through holes are arranged in parallel.
  • the inner walls of the through holes formed in the substrate are non-through holes that are not plated with a metal such as copper. If they are non-through holes, it is possible to prevent electricity from flowing from the thermoelectric conversion element mounted in the through hole to the inner wall.
  • the wiring 31 is formed from a conductive material that electrically connects the p-type thermoelectric conversion element 21 and the n-type thermoelectric conversion element 22.
  • the wiring 31 may be formed from copper plating or copper foil. Or, it may be formed from a conductive paste of carbon nanotubes.
  • the wiring 31 may be formed from carbon nanotubes themselves or using the thermoelectric conversion element composition of the present application for both filling and wiring, subsequent plating wiring is unnecessary, which simplifies the process and reduces costs.
  • the thickness of the wiring 31 is, for example, 1 ⁇ m to 50 ⁇ m.
  • conductive materials for forming the wiring 31 include transparent electrode materials such as indium tin oxide (ITO) and zinc oxide (ZnO), metal electrode materials such as silver, copper, gold and aluminum, carbon materials such as CNT and graphene, organic materials such as PEDOT (poly(3,4-ethylenedioxythiophene))/PSS (poly(4-styrenesulfonic acid)), conductive pastes in which conductive particles such as silver and carbon are dispersed, conductive pastes containing metal nanowires such as silver, copper and aluminum, etc.
  • metal electrode materials such as aluminum, gold, silver or copper, or conductive pastes containing these metals are preferred.
  • the extraction electrode 41 may be a plated coating with excellent electrical conductivity, and may be formed by a known method. Examples include copper plating, gold plating, silver plating, and tin plating.
  • thermoelectric conversion module 20 according to a fourth embodiment of the present disclosure will be described. However, descriptions overlapping with those of the thermoelectric conversion module 10 will be omitted.
  • thermoelectric conversion module 20 according to the fourth embodiment either a p-type thermoelectric conversion element 21 or an n-type thermoelectric conversion element 22 is mounted in a through hole formed in the substrate 11.
  • FIG. 3 is a diagram illustrating an example of the upper surface of the thermoelectric conversion module 20 in a state in which the p-type thermoelectric conversion element 21 is mounted.
  • FIG. 4 is a cross-sectional view showing a cut surface when wiring 31 is formed at the position shown by the dotted line in FIG. 3 and cut along line C-D in FIG. 3. As shown in FIG.
  • thermoelectric conversion module 20 only the p-type thermoelectric conversion element 21 is mounted in a through hole formed in the substrate 11.
  • the substrate 11 has a plurality of via holes 51.
  • the via holes 51 may be arranged between the p-type thermoelectric conversion elements 21.
  • the p-type thermoelectric conversion elements 21 and the via holes 51 are alternately wired in series and electrically connected as shown in FIG. 4.
  • an n-type thermoelectric conversion element 22 may be mounted instead of the p-type thermoelectric conversion element 21.
  • the p-type thermoelectric conversion element 21 and the n-type thermoelectric conversion element 22 are formed from the above-mentioned thermoelectric conversion element composition.
  • the via holes 51 are holes for providing electrical continuity between the front and back of the substrate 11, and can be formed by known techniques. Typically, wiring is achieved by plating the inside of the holes with a metal such as copper.
  • the hole diameter ( ⁇ ) of the via holes may be 0.1 mm to 1.0 mm. It is preferably 0.1 mm to 0.5 mm, and more preferably 0.1 mm to 0.3 mm. In this way, the hole diameter of the via holes is extremely small compared to the hole diameter of the through-hole in which the thermoelectric conversion element is mounted. Therefore, the via holes can be formed without reducing the number of thermoelectric conversion elements on the substrate, and the performance of the thermoelectric conversion module is not reduced by adding via holes.
  • the arrangement of the thermoelectric conversion elements and the via holes on the substrate is not particularly limited as long as they can be wired alternately in series.
  • thermoelectric conversion module 20 only needs to be filled with either the p-type thermoelectric conversion elements 21 or the n-type thermoelectric conversion elements 22. If the module is configured with only p-type thermoelectric conversion elements, the thermoelectric conversion elements can be stabilized over the long term, and the life of the thermoelectric conversion module can be extended. If the module is configured with only n-type thermoelectric conversion elements, this is preferable because n-type thermoelectric conversion elements are easy to make using epoxy resin. In this way, it is only necessary to fill with either one of the thermoelectric conversion elements, and the manufacturing process can be simplified. In addition, the number of materials can be reduced, which allows costs to be reduced.
  • Method of manufacturing composition for thermoelectric conversion element In the method for producing a composition for thermoelectric conversion elements according to the fifth embodiment of the present disclosure, first, nanocarbon is dispersed in a solvent to prepare a nanocarbon dispersion. A commercially available nanocarbon dispersion may be prepared. Next, either a p-type dopant or an n-type dopant is added to the nanocarbon dispersion. At this time, it is preferable that the dopant can be dissolved in the solvent.
  • the method for preparing the nanocarbon dispersion there is no particular limitation on the method for preparing the nanocarbon dispersion, and it can be performed at room temperature and normal pressure using a normal mixing device or the like. Each component may be dispersed and dissolved by stirring, shaking, or the like.
  • the solvent may be heated to a temperature between room temperature (25°C) and the boiling point, the dispersion time may be extended, or ultrasonic treatment or the like may be performed.
  • the binder resin is added while removing the solvent from the nanocarbon dispersion liquid, and the solvent and the binder resin are replaced to prepare a composition for thermoelectric conversion elements.
  • the method for removing the solvent can be a known method.
  • the solvent may be removed by evaporating it by heating. In this manner, a composition for thermoelectric conversion elements having fluidity such as a paste or ink is prepared.
  • the solvent may be any solvent capable of dispersing nanocarbon, and may be water, an organic solvent, or a mixture of these.
  • organic solvents include methyl ethyl ketone (MEK), alcohol, chloroform, dimethylformamide (DMF), N-methyl-2-pyrrolidone (NMP), dimethyl sulfoxide (DMSO), chlorobenzene, dichlorobenzene, benzene, toluene, xylene, mesitylene, tetralin, tetramethylbenzene, pyridine, cyclohexanone, acetone, diethyl ether, tetrahydrofuran (THF), t-butyl methyl ether, dimethoxyethane, and diglyme.
  • the solvent may be used alone or in combination of two or more.
  • the amount of solvent is not particularly limited as long as it is an amount that can disperse the nanocarbon. Furthermore, it is preferable that the amount of solvent is an amount that can dissolve the required amount of dopant.
  • thermoelectric conversion module As a manufacturing method of a thermoelectric conversion module according to a sixth embodiment of the present disclosure, a manufacturing method in which p-type and n-type compositions for thermoelectric conversion elements are filled into through holes in a substrate will be described.
  • a substrate having a plurality of through holes formed therein is prepared.
  • the preparation step may include forming the through holes in the substrate, or may include preparing a substrate having through holes already formed therein.
  • the through holes may be formed using a known method.
  • the p-type thermoelectric conversion element composition is filled into the multiple through holes so that the p-type thermoelectric conversion elements and the n-type thermoelectric conversion elements can be alternately connected in series, and the through holes not filled with the p-type thermoelectric conversion element composition are filled with the n-type thermoelectric conversion element composition.
  • Either the p-type or n-type thermoelectric conversion element composition may be filled first.
  • the through holes not filled with the p-type thermoelectric conversion element composition are masked, and the unmasked through holes are filled with the p-type thermoelectric conversion element composition.
  • the through holes not filled with the n-type thermoelectric conversion element composition are masked, and the unmasked through holes are filled with the n-type thermoelectric conversion element composition.
  • the filling may be performed by filling with a squeegee, or a vacuum filling machine may be used.
  • a p-type thermoelectric conversion element is formed from the composition for p-type thermoelectric conversion elements, and an n-type thermoelectric conversion element is formed from the composition for n-type thermoelectric conversion elements.
  • the binder resin is a thermosetting resin
  • the binder resin is cured by heating to the curing temperature of the resin to form a thermoelectric conversion element.
  • the curing temperature and time are appropriately selected depending on the type of binder resin used.
  • the binder resin is a thermoplastic resin
  • the binder resin is solidified by a method that solidifies the resin (cooling, drying, etc.) to form a thermoelectric conversion element.
  • the cured or solidified material protruding from the through hole is removed by grinding.
  • the p-type thermoelectric conversion elements and the n-type thermoelectric conversion elements are alternately connected in series on the first surface of the substrate and the second surface opposite to the first surface of the substrate using a conductive material. For example, as shown in FIG. 2, the p-type thermoelectric conversion elements and the n-type thermoelectric conversion elements are electrically connected by plating.
  • thermoelectric conversion module includes a plurality of p-type thermoelectric conversion elements and a plurality of n-type thermoelectric conversion elements mounted in the through holes of the substrate.
  • the front and back surfaces of the thermoelectric conversion module may be covered with solder resist. By covering the front and back surfaces with solder resist, electronic components can be mounted and insulation can be ensured.
  • the solder resist is preferably made of a material with high heat dissipation properties.
  • thermoelectric conversion module As another method for manufacturing a thermoelectric conversion module, a method for manufacturing the module by stacking two substrates will be described. First, an upper substrate to be placed on the upper side and a lower substrate to be placed on the lower side are prepared. Two lead electrodes are formed on either the upper substrate or the lower substrate by copper plating or the like. Furthermore, a plurality of wirings are formed on each of the upper substrate and the lower substrate by copper plating or the like.
  • the wirings are arranged so that a part of the wiring 1 of the upper substrate overlaps with a part of the wiring 2 of the lower substrate, another part of the wiring 2 of the lower substrate overlaps with a part of the wiring 3 of the upper substrate, and another part of the wiring 3 of the upper substrate overlaps with a part of the wiring 4 of the lower substrate (hereinafter the same). That is, the wirings are arranged so that the plurality of wirings of the upper substrate and the plurality of wirings of the lower substrate can be electrically connected in series with one electrode as the starting point and the other electrode as the end point.
  • the shape of the wirings can be a rectangle, an oval, a racetrack shape, an ellipse, or the like.
  • the wiring is performed so that one circular portion of wiring 1 on the upper substrate overlaps with one circular portion of wiring 2 on the lower substrate, the other circular portion of wiring 2 on the lower substrate overlaps with one circular portion of wiring 3 on the upper substrate, and the other circular portion of wiring 3 on the upper substrate overlaps with one circular portion of wiring 4 on the lower substrate (and so on).
  • an insulating layer is prepared.
  • the insulating layer is a middle layer between the upper substrate and the lower substrate, and the thermoelectric conversion module has three layers in the order of upper substrate/insulating layer/lower substrate.
  • the insulating layer has a plurality of holes, and the shapes thereof can be circular, square, etc.
  • the holes are formed at positions such that the overlapping portions of the wiring of the upper substrate and the wiring of the lower substrate can be electrically connected when the layers are laminated in the order of upper substrate/insulating layer/lower substrate.
  • a paste (or ink) of the composition for thermoelectric conversion elements is placed on the wiring of the upper substrate and the lower substrate.
  • the shape of the wiring is described as a racetrack shape.
  • An appropriate amount of the paste (or ink) of the composition for n-type thermoelectric conversion elements is placed on one of the two circular parts of the racetrack shape on the upper substrate.
  • An appropriate amount of the paste (or ink) of the composition for p-type thermoelectric conversion elements is placed on one of the two circular parts of the racetrack shape on the lower substrate.
  • the composition for n-type thermoelectric conversion elements on the upper substrate may be placed in contact with the circular part of the lower substrate where the composition is not placed, and the composition for p-type thermoelectric conversion elements on the lower substrate may be placed in contact with the circular part of the upper substrate where the composition is not placed.
  • the upper and lower substrates are stacked with the insulating layer between them so that the surfaces having wiring face each other.
  • thermoelectric conversion element composition arranged on one circular portion of the upper substrate passes through the holes in the insulating layer and comes into contact with the composition-free circular portion of the lower substrate.
  • the p-type thermoelectric conversion element composition arranged on one circular portion of the lower substrate passes through the holes in the insulating layer and comes into contact with the composition-free circular portion of the upper substrate.
  • the thermoelectric conversion module having three layers, ie, upper substrate/insulating layer/lower substrate is pressed from above and below, and the composition for thermoelectric conversion elements is cured or solidified by heating or the like. In this manner, a thermoelectric conversion module can be fabricated from two substrates and an insulating layer.
  • thermoelectric conversion module As a method for manufacturing a thermoelectric conversion module according to a seventh embodiment of the present disclosure, a method for manufacturing the module by filling only a p-type thermoelectric conversion element composition into a through hole of a substrate will be described. Note that an n-type thermoelectric conversion element composition may be used instead of the p-type thermoelectric conversion element composition.
  • a substrate having a plurality of through holes and a plurality of via holes formed therein is prepared.
  • the preparation step may include forming through holes or via holes in the substrate, or may include preparing a substrate having through holes or via holes already formed therein.
  • the formation of the through holes and the via holes can be performed by a known method. At this point, the inside of the via holes may or may not be metal plated.
  • the through holes are filled with a composition for a p-type thermoelectric conversion element by using a squeegee or a vacuum filling machine.
  • a p-type thermoelectric conversion element is formed from the composition for p-type thermoelectric conversion elements.
  • the binder resin is a thermosetting resin
  • the binder resin is cured by heating to the curing temperature of the resin to form a thermoelectric conversion element.
  • the curing temperature and time are appropriately selected depending on the type of binder resin used.
  • the binder resin is a thermoplastic resin
  • the binder resin is solidified by a method that solidifies the resin (cooling, drying, etc.) to form a thermoelectric conversion element.
  • thermoelectric conversion elements and the via holes are connected to each other by using a conductive material on the first surface of the substrate and the second surface opposite to the first surface of the substrate so that they are alternately arranged in series.
  • the p-type thermoelectric conversion elements and the via holes are electrically connected by plating. Even if the inside of the via holes is not metal-plated, plating can be applied at this point.
  • a thermoelectric conversion module is fabricated that includes a plurality of p-type thermoelectric conversion elements mounted in the through holes of the substrate and a plurality of via holes.
  • thermoelectric conversion module in which thermoelectric conversion elements are mounted in the thickness direction of a substrate can have a large area in contact with a heat source.
  • the produced thermoelectric conversion module can be used to recover waste heat from the industry as electric energy.
  • the heat generated by power elements such as IGBTs (insulated gate bipolar transistors) and packaged components can be recovered as electric energy, improving the fuel efficiency of EVs (electric vehicles).
  • IGBTs insulated gate bipolar transistors
  • EVs electric vehicles
  • a thermoelectric conversion module can be formed locally under an IC packaged component that requires heat dissipation, and used as a cooling mechanism for the packaged component. It may also be applied to heaters and coolers for steering wheels and seats in vehicles.
  • thermoelectric conversion module It may be used as a heat flow sensor by reading the thermoelectromotive force, or as a sensor power source in a place where there is no power source.
  • a heat dissipation material, a water-cooled cooler, or the like may be placed in close contact with the thermoelectric conversion module.
  • thermoelectric conversion element compositions for thermoelectric conversion elements having different carbon nanotube contents were prepared.
  • the prepared compositions for thermoelectric conversion elements did not contain a surfactant.
  • the materials used are as follows: Carbon nanotube dispersion: CNT, methyl ethyl ketone (MEK dispersion, manufactured by Meijo Nano Carbon Co., Ltd.) Binder resin (high viscosity): 50,000 mPa ⁇ s (X-1987D, manufactured by Fine Polymers Co., Ltd.) Binder resin (low viscosity): 2,200 mPa ⁇ s (EX-0547, Fine Polymers Co., Ltd.)
  • FIG. 5 is a graph plotting the relationship between the carbon nanotube content and electrical resistivity for compositions for thermoelectric conversion elements using two types of binder resins with different viscosities (high viscosity, low viscosity).
  • the electrical resistivity was measured using MCP-T610 (manufactured by Mitsubishi Chemical Analytech Co., Ltd.) as follows. Using the composition for thermoelectric conversion elements, a thin film (thickness: about 10 ⁇ m) was formed on a glass substrate before curing. The thin film was cured in a drying oven (180°C, 30 min). ⁇ Measurements were made using the above equipment.
  • Fig. 5 shows that the electrical resistivity of the thermoelectric conversion element composition decreases as the carbon nanotube content increases, and that the electrical resistivity can be further reduced by decreasing the viscosity of the binder resin.
  • Table 1 shows the carbon nanotube content and the measured electrical resistivity for compositions for thermoelectric conversion elements using a binder resin (low viscosity).
  • the electrical conductivity of the thermoelectric conversion element composition containing carbon nanotubes is 10 1 ( ⁇ cm) or less, since sufficient electrical conductivity can be obtained. Therefore, it is particularly preferable that the carbon nanotube content in the binder resin is 0.2 wt % or more.
  • thermoelectric conversion element composition containing a surfactant and a thermoelectric conversion element composition not containing a surfactant were prepared, and formed into the bulk shape shown in FIG. 6 (CNT content 0.75 wt %, ⁇ 3.0 mm, thickness 1.6 mm).
  • Carbon nanotube dispersion (containing surfactant): CNT, methyl ethyl ketone (MEK dispersion, manufactured by Meijo Nano Carbon Co., Ltd.) Carbon nanotube dispersion (no surfactant): CNT, methyl ethyl ketone (MEK dispersion, no dispersant, manufactured by Meijo Nano Carbon Co., Ltd.) Binder resin (low viscosity): 2,200 mPa ⁇ s (EX-0547, Fine Polymers Co., Ltd.) Table 2 shows the measured electrical resistivity with and without a surfactant. In Example 7, which did not contain a surfactant, the electrical resistance value was further reduced. Therefore, it is understood that the electrical resistance value can be controlled by the presence or absence of a surfactant.

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Abstract

Afin d'obtenir une composition pour éléments de conversion thermoélectrique permettant d'intégrer facilement un matériau d'élément de conversion thermoélectrique dans un substrat, la présente invention concerne une composition pour éléments de conversion thermoélectrique qui a une certaine fluidité et contient des nanocarbones, soit un dopant qui confère aux nanocarbones des caractéristiques de semi-conducteur de type p, soit un dopant qui confère aux nanocarbones des caractéristiques de semi-conducteur de type n, ainsi qu'une résine liante.
PCT/JP2023/036445 2022-10-07 2023-10-05 Composition pour éléments de conversion thermoélectrique, module de conversion thermoélectrique, procédé de production de composition pour éléments de conversion thermoélectrique, et procédé de production de module de conversion thermoélectrique WO2024075821A1 (fr)

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Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014239092A (ja) * 2013-06-06 2014-12-18 公立大学法人首都大学東京 熱電変換材料及び熱電変換素子
JP2017135337A (ja) * 2016-01-29 2017-08-03 株式会社東芝 熱電変換素子
WO2021200264A1 (fr) * 2020-03-30 2021-10-07 リンテック株式会社 Module de conversion thermoélectrique

Patent Citations (3)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
JP2014239092A (ja) * 2013-06-06 2014-12-18 公立大学法人首都大学東京 熱電変換材料及び熱電変換素子
JP2017135337A (ja) * 2016-01-29 2017-08-03 株式会社東芝 熱電変換素子
WO2021200264A1 (fr) * 2020-03-30 2021-10-07 リンテック株式会社 Module de conversion thermoélectrique

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