JP2021150403A - Thermoelectric conversion module - Google Patents

Abstract

To provide a thermoelectric conversion module which enhances followability to a heat source surface including a curved shape and can further improve thermoelectric performance.SOLUTION: A thermoelectric conversion module includes a first substrate having a first electrode, a second substrate having a second electrode, a chip of a thermoelectric conversion material composed of a thermoelectric semiconductor composition, and a joint material layer for joining one surface of the chip of the thermoelectric conversion material and the first electrode, and joining the other surface of the chip of the thermoelectric conversion material and the second electrode. The joint material layer is composed of a conductive adhesive containing a resin and a conductive material, and an elastic modulus at 25°C after curing of the joining material layer is 10-3,000 MPa.SELECTED DRAWING: Figure 2

Description

The present invention relates to a thermoelectric conversion module that performs mutual energy conversion between heat and electricity.

Conventionally, as one of the effective utilization means of energy, there is a device in which thermal energy and electric energy are directly converted into each other by a thermoelectric conversion module having a thermoelectric effect such as the Seebeck effect and the Perche effect.
As the thermoelectric conversion module, the use of a so-called π-type thermoelectric conversion element is known. In the π-type, a pair of electrodes separated from each other are provided on the substrate, for example, a P-type thermoelectric element is provided on the-one electrode and an N-type thermoelectric element is provided on the other electrode, also separated from each other. , The upper surfaces of both thermoelectric semiconductor materials are connected to the electrodes of the opposing substrates.
Under these circumstances, in recent years, when the heat source surface on which the thermoelectric conversion module is installed has a curved surface shape, the thermoelectric conversion module is made to follow the heat source surface and the adhesion is improved from the viewpoint of efficient power generation or cooling. Therefore, there is a demand for improving the flexibility of the thermoelectric conversion module.
In order to satisfy this requirement, for example, Patent Document 1 describes a π-type thermoelectric conversion element including a P-type thermoelectric semiconductor element and an N-type thermoelectric semiconductor element, and a P-type thermoelectric semiconductor element and an N-type thermoelectric semiconductor element, respectively. A thermoelectric conversion module with a flexible wiring directly and electrically connected to the device is disclosed. Here, the flexible wiring is configured to be expandable and contractible according to the displacement of at least one of the P-type thermoelectric semiconductor element and the N-type thermoelectric semiconductor element, and as the thermoelectric conversion module, the flexible substrate in which the thermoelectric semiconductor element has elasticity and a heat source. The heat-resistant substrate contains polyimide, the flexible substrate contains silicone resin, and the flexible wiring contains conductive particles and silicone resin.

Japanese Unexamined Patent Publication No. 2011-91243

However, in the thermoelectric conversion module of Patent Document 1, on the heat-resistant substrate side mounted on the heat source, one surface of the thermoelectric semiconductor element is joined to the copper foil wiring (electrode) on the heat-resistant substrate via a solder alloy. There is. Normally, since a solder alloy has a relatively high elastic modulus, its extensibility is not sufficient when it is mounted on a heat source surface including a curved surface shape, its followability to the heat source surface is suppressed, and its thermoelectric performance is efficient. It may not be obtained.

An object of the present invention is to provide a thermoelectric conversion module capable of improving followability to a heat source surface including a curved surface shape and further improving thermoelectric performance.

As a result of diligent studies to solve the above problems, the present inventors have made the elastic modulus at 25 ° C. after curing within a specific range in the bonding between the chip and the electrode of the thermoelectric conversion material constituting the thermoelectric conversion module. By using a certain bonding material layer containing a resin and a conductive material, not only the bonding property between the chip and the electrode of the thermoelectric conversion material but also the followability to the heat source surface including the curved shape of the thermoelectric conversion module is enhanced. The present invention was completed.
That is, the present invention provides the following (1) to (14).
(1) One surface of a first substrate having a first electrode, a second substrate having a second electrode, a chip of a thermoelectric conversion material made of a thermoelectric semiconductor composition, and a chip of the thermoelectric conversion material. A thermoelectric conversion module comprising the first electrode and a bonding material layer for bonding the other surface of the chip of the thermoelectric conversion material and the second electrode, respectively, wherein the bonding material layer is a resin. A thermoelectric conversion module comprising a conductive adhesive containing a conductive material and having an elastic coefficient at 25 ° C. after curing of the bonding material layer of 10 to 3000 MPa.
(2) The thermoelectric conversion module according to (1) above, wherein the resin is selected from an epoxy resin, a silicone resin, a polyimide resin, and a polyurethane resin.
(3) The conductive material contains metal particles, and the metal particles are selected from silver particles, nickel particles, gold particles, indium particles, tin particles, aluminum particles, palladium particles, titanium particles and copper particles. The thermoelectric conversion module according to (1) above, which is one kind selected from silver particles, nickel particles, and copper particles which are a mixture of two or more kinds, or a mixture of two or more kinds.
(4) The distance between the chips of the thermoelectric conversion material adjacent to each other in the extending direction (direction orthogonal to the bending direction) of the bent portion of the thermoelectric conversion module is the distance between the chips of the thermoelectric conversion material in the extending direction of the bent portion. The thermoelectric conversion module according to (1) above, which is 0.1 or more and less than 3 times the length.
(5) The thermoelectric conversion module according to (1) above, wherein the elastic modulus is 10 to 1000 MPa.
(6) The thermoelectric conversion module according to any one of (1) to (5) above, wherein the bonding material layer has a thickness of 10 to 1000 μm.
(7) The thermoelectric conversion module according to any one of (1) to (6) above, further comprising a bonding material receiving layer containing a metal material between the chip of the thermoelectric conversion material and the bonding material layer.
(8) The above (7), wherein the metal material is at least one selected from an alloy containing gold, silver, rhodium, platinum, chromium, palladium, tin, nickel, and any of these metal materials. Thermoelectric conversion module.
(9) The thermoelectric conversion module according to (7) or (8) above, wherein the bonding material receiving layer has a thickness of 10 nm to 50 μm.
(10) The thermoelectric conversion module according to any one of (1) to (9) above, wherein the thermoelectric semiconductor composition contains one or both of a thermoelectric semiconductor material, a heat-resistant resin, an ionic liquid and an inorganic ionic compound.
(11) The thermoelectric conversion module according to (10) above, wherein the heat-resistant resin is a polyimide resin, a polyamide resin, a polyamide-imide resin, or an epoxy resin.
(12) The thermoelectric according to (10) above, wherein the thermoelectric semiconductor material is a bismuth-tellurium-based thermoelectric semiconductor material, a tellurium-based thermoelectric semiconductor material, an anti-montellurium-based thermoelectric semiconductor material, or a bismuth selenide-based thermoelectric semiconductor material. Conversion module.
(13) The thermoelectric conversion module according to (12) above, wherein the bismuth-tellurium thermoelectric semiconductor material is P-type bismuthtellide, N-type bismuthellide, or Bi ₂ Te _3.
(14) The first substrate and the second substrate are made of a plastic film, and the plastic films are independently a polyimide film, a polyamide film, a polyetherimide film, a polyaramid film, or a polyamideimide film. The thermoelectric conversion module according to any one of (1) to (13).

According to the present invention, it is possible to provide a thermoelectric conversion module capable of improving the followability to a heat source surface including a curved surface shape and further improving the thermoelectric performance.

It is sectional drawing for demonstrating an example of the structure of the thermoelectric conversion module including the bonding material layer used in this invention. It is sectional drawing for demonstrating another example of the structure of the thermoelectric conversion module including the bonding material layer used in this invention.

[Thermoelectric conversion module]
The thermoelectric conversion module of the present invention comprises a first substrate having a first electrode, a second substrate having a second electrode, a chip of a thermoelectric conversion material composed of a thermoelectric semiconductor composition, and the thermoelectric conversion material. A thermoelectric conversion module comprising a bonding material layer for bonding one surface of a chip and the first electrode, and the other surface of the chip of the thermoelectric conversion material and the second electrode, respectively. The bonding material layer is made of a conductive adhesive containing a resin and a conductive material, and has an elastic coefficient of 10 to 3000 MPa at 25 ° C. after curing of the bonding material layer.
In the thermoelectric conversion module of the present invention, the flexibility of the entire thermoelectric conversion module is improved by joining the upper and lower surfaces of the thermoelectric conversion material chip to the opposing electrodes using a bonding material layer having an elastic modulus of 10 to 3000 MPa. , It is possible to improve the followability to the heat source surface including the curved surface shape. Therefore, the adhesion to the heat source surface is improved, the temperature difference can be efficiently applied to the upper and lower surfaces of the thermoelectric conversion module, and the thermoelectric performance can be further improved.
In the present specification, "one surface of the chip of the thermoelectric conversion material" and "the other surface of the chip of the thermoelectric conversion material" refer to, for example, the shape of the chip of the thermoelectric conversion material as a rectangular parallelepiped or a columnar shape. When viewed, it means the facing upper and lower surfaces when viewed from the front.

FIG. 1 is a cross-sectional view for explaining an example of the configuration of a thermoelectric conversion module including a bonding material layer used in the present invention. The thermoelectric conversion module 1A is composed of a so-called π-type thermoelectric conversion element and faces each other. It has a first substrate 2a and a second substrate 2b, and is between a first electrode 3a formed on the first substrate 2a and a second electrode 3b formed on the second substrate 2b. , The chip 4 of the P-type thermoelectric conversion material and the chip 5 of the N-type thermoelectric conversion material are included via the bonding material layer 6.
FIG. 2 is a cross-sectional view for explaining another example of the configuration of the thermoelectric conversion module including the bonding material layer used in the present invention. The thermoelectric conversion module 1B is a chip 4 of a P-type thermoelectric conversion material in FIG. A bonding material receiving layer 7 is included between the chip 5 of the N-type thermoelectric conversion material and the bonding material layer 6.
In the present invention, one surface of the chip 4 of the P-type thermoelectric conversion material and the chip 5 of the N-type thermoelectric conversion material and the first electrode 3a are used, and the chip 4 of the P-type thermoelectric conversion material and the N-type thermoelectric conversion material are used. By joining the other surface of the chip 5 and the second electrode 3b via the bonding material layer 6, not only the bondability between the chip and the electrode of the thermoelectric conversion material but also the flexibility of the entire thermoelectric conversion module is improved. However, the followability to the heat source surface including the curved shape is improved.

<Joining material layer>
A bonding material layer is used in the thermoelectric conversion module of the present invention.
The bonding material layer electrically and physically joins the upper and lower surfaces of the thermoelectric conversion material chip to the electrodes facing each other, and has a specific elastic modulus to improve the flexibility of the entire thermoelectric conversion module. ..
The bonding material layer is made of a conductive adhesive containing a resin and a conductive material (hereinafter, may be referred to as a "conductive composition").

The resin of the conductive adhesive is not particularly limited, and those that are cured by irradiating with energy rays such as electron beam, radiation, and ultraviolet rays, or those that are cured by heating can be applied. In the present invention, it is preferable that the chips and electrodes of the thermoelectric conversion material have low transparency to ultraviolet rays and the like, and are thermosetting resins from the viewpoint of equipment cost.
Specifically, epoxy resins such as bisphenol type epoxy resin, novolak type epoxy resin, cyclic epoxy resin, and alicyclic epoxy resin; silicone resin, unsaturated polyester resin, phenol resin, melamine resin, polyimide resin, polyurethane resin, etc. Can be mentioned.
Among these, an epoxy resin, a silicone resin, a polyimide resin, and a polyurethane resin are preferably selected. From the viewpoint of heat resistance and flexibility, epoxy resin and silicone resin are more preferable. Only one type of these resins may be used alone, or two or more types may be used in combination.

The conductive material is not particularly limited, and examples thereof include carbon particles, carbon nanotubes, and metal particles. Among these, metal particles are preferable from the viewpoint of obtaining high conductivity. The metal particles are preferably one kind selected from silver particles, nickel particles, gold particles, indium particles, tin particles, aluminum particles, palladium particles, titanium particles and copper particles, or a mixture of two or more kinds, more preferably. Are silver particles, nickel particles, and copper particles.
The content of the conductive material in the conductive composition depends on the type of the conductive material, and is appropriately adjusted as long as it satisfies the elastic modulus specified in the present invention and does not impair the thermoelectric performance. Generally, it is 1 to 90% by mass, preferably 20 to 90% by mass, more preferably 30 to 90% by mass, and further preferably 40 to 90% by mass. When the content of the conductive material in the conductive composition is within the above range, a bonding material layer having conductivity that satisfies the elastic modulus specified in the present invention and does not impair thermoelectric performance can be obtained.
In the present specification, the conductivity means a state in which ^{the electrical resistivity is less than 1 × 10 2 Ω · m.}

The average particle size of the metal particles as the conductive material is preferably 0.1 to 10.00 μm. When the average particle size of the metal particles is in the range of 0.1 to 10.00 μm, the effects of contact frequency between the particles, reduction of resistance due to an increase in the contact area, and prevention of disconnection due to the fact that the particles can be densely mixed can be obtained. The particle shape of the metal particles is not particularly limited, and examples thereof include a spherical shape, a needle shape, a scaly shape, a polyhedral shape, and an indefinite shape.
The average particle size of the metal particles when the particle shape of the metal particles is spherical was obtained by measuring with a laser diffraction type particle size analyzer (CILAS, 1064 type), and was used as the median value of the particle size distribution. ..

The elastic modulus of the bonding material layer at 25 ° C. after curing is 10 to 3000 MPa. If the elastic modulus of the bonding material layer is less than 10 MPa, the conductivity tends to decrease, and it may be difficult to obtain sufficient thermoelectric performance. Further, when the elastic modulus of the bonding material layer exceeds 3000 MPa, the flexibility is lowered and the followability to the heat source surface including the curved surface shape of the thermoelectric conversion module is easily suppressed.
The elastic modulus of the bonding material layer is preferably 10 to 1500 MPa, more preferably 10 to 1000 MPa, and even more preferably 100 to 500 MPa.
When the elastic modulus of the bonding material layer is within this range, the balance between conductivity and flexibility becomes good, and as a result, the followability of the thermoelectric conversion module to the heat source surface including the curved surface shape is enhanced, and the thermoelectric performance is improved.

The bonding material layer is formed, for example, by dissolving the resin or the conductive material in a solvent or the like to form a paste, and stencil printing method, screen printing method, dispensing method or the like on a predetermined electrode or on the chip side of the thermoelectric conversion material. It is carried out by a known method of. The heating temperature varies depending on the resin used, the conductive material, the substrate material, and the like, but is usually carried out at 80 to 280 ° C. for 3 to 20 minutes.

The thickness of the bonding material layer is 10 to 1000 μm, preferably 10 to 200 μm, more preferably 20 to 150 μm, still more preferably 30 to 130 μm, and particularly preferably 40 to 120 μm.
When the thickness of the bonding material layer is within this range, the bonding property between the chip and the electrode of the thermoelectric conversion material and the followability to the heat source surface including the curved surface shape of the thermoelectric conversion module are good.

Examples of conductive adhesive products include SX-ECA48 (trade name: Semedyne, elastic modulus: 225 MPa (25 ° C.)), ECA300 (trade name: Nihon Handa, elastic modulus: 430 MPa (25 ° C.)). , EPS-110A (trade name: manufactured by Muromachi Chemical Co., Ltd., elastic modulus: 14 MPa (25 ° C.)) and the like can be applied.

In the thermoelectric conversion module of the present invention, when the thermoelectric conversion module is mounted while being bent so as to follow an article to be mounted as a heat source, the extending direction (orthogonal to the bending direction) of the bent portion of the thermoelectric conversion module is Direction: When the article is a cylinder, for example, the bent portion of the thermoelectric conversion module extends in the length direction orthogonal to the radial direction of the cylinder), and the distance between the chips of the adjacent thermoelectric conversion materials is It is preferably 0.1 or more and less than 3 times, more preferably 0.3 or more and 2.6 times or less with respect to the length of the chip of the thermoelectric conversion material in the extending direction of the bent portion of the thermoelectric conversion module. More preferably, it is 0.5 or more and 2.2 times or less. However, all the chips of the thermoelectric conversion material have substantially the same dimensions.
When the distance between the chips of the thermoelectric conversion material adjacent to each other in the extending direction of the bending portion of the thermoelectric conversion module is within the above range with respect to the length of the chips of the thermoelectric conversion material in the extending direction of the bending portion, the thermoelectric conversion is performed. The bondability between the material chip and the electrode can be maintained, and the followability to the heat source surface including the curved surface shape of the thermoelectric conversion module can be improved.

<Joining material receiving layer>
It is preferable to use a bonding material receiving layer for the thermoelectric conversion module of the present invention.
The bonding material receiving layer has a function of improving the bondability of the bonding material layer on the electrode side facing the chip of the thermoelectric conversion material, and has one surface of the chip of the thermoelectric conversion material and the other surface of the chip of the thermoelectric conversion material. It is preferable to laminate directly on (upper and lower surfaces).

The bonding material receiving layer contains a metallic material. The metal material is preferably at least one selected from alloys containing gold, silver, rhodium, platinum, chromium, palladium, tin, nickel and any of these metal materials. Among these, more preferably, it has a two-layer structure of gold, silver, nickel or tin and gold, nickel and gold, and silver is further preferable from the viewpoint of material cost, high thermal conductivity and bonding stability.
Further, the bonding material receiving layer may be formed by using a paste material containing a solvent or a resin component in addition to the metal material. When a paste material is used, it is preferable to remove the solvent and the resin component by firing or the like as described later. As the paste material, silver paste and aluminum paste are preferable.

The thickness of the bonding material receiving layer is preferably 10 nm to 50 μm, more preferably 50 nm to 16 μm, further preferably 200 nm to 4 μm, and particularly preferably 500 nm to 3 μm. When the thickness of the bonding material receiving layer is within this range, the adhesion of the thermoelectric conversion material to the chip surface and the adhesion to the surface of the bonding material layer on the electrode side are excellent, and highly reliable bonding can be obtained. .. Further, since the thermal conductivity can be maintained high as well as the conductivity, the thermoelectric performance of the thermoelectric conversion module is not deteriorated as a result and is maintained.
As the bonding material receiving layer, the metal material may be formed as it is and used as a single layer, or two or more metal materials may be laminated and used in multiple layers. Further, a film may be formed as a composition in which a metal material is contained in a solvent, a resin or the like. However, in this case, from the viewpoint of maintaining high conductivity and high thermal conductivity (maintaining thermoelectric performance), the resin component including the solvent should be removed by firing or the like as the final form of the bonding material receiving layer. Is preferable.

The bonding material receiving layer is formed using the above-mentioned metal material.
As a method of forming the bonding material receiving layer, after providing a bonding material receiving layer in which a pattern is not formed on the chip of the thermoelectric conversion material, a known physical treatment or chemical treatment mainly based on a photolithography method is performed. Alternatively, a method of processing into a predetermined pattern shape by using them in combination, or a method of forming a pattern of a direct bonding material receiving layer by a screen printing method, a stencil printing method, an inkjet method, or the like can be mentioned.
Examples of the method for forming the bonding material receiving layer in which the pattern is not formed include PVD (Physical Vapor Deposition) such as vacuum deposition, sputtering, and ion plating, thermal CVD, and atomic layer deposition (ALD). Vacuum film formation method such as CVD (Chemical Vapor Deposition Deposition), various coating methods such as dip coating method, spin coating method, spray coating method, gravure coating method, die coating method, doctor blade method, etc. Examples thereof include a process, a silver salt method, an electrolytic plating method, a electroless plating method, and laminating of metal foils, which are appropriately selected according to the material of the bonding material receiving layer.
In the present invention, the bonding material receiving layer is required to have high conductivity and high thermal conductivity from the viewpoint of maintaining thermoelectric performance. Therefore, the screen printing method, the stencil printing method, the electrolytic plating method, the electroless plating method and the vacuum It is preferable to use a bonding material receiving layer formed by a film forming method.

<Chip of thermoelectric conversion material>
The thermoelectric conversion material chip used in the thermoelectric conversion module of the present invention is made of a thin film made of a thermoelectric semiconductor composition. Preferably, it comprises a thermoelectric semiconductor material (hereinafter, may be referred to as "thermoelectric semiconductor particles"), a heat-resistant resin described later, and a thermoelectric semiconductor composition containing one or both of an ionic liquid and an inorganic ionic compound described later. It consists of a thin film.

(Thermoelectric semiconductor material)
The thermoelectric semiconductor material used in the present invention, that is, the thermoelectric semiconductor material constituting the chip of the P-type thermoelectric conversion material and the chip of the N-type thermoelectric conversion material, can generate thermoelectromotive force by imparting a temperature difference. The material is not particularly limited as long as it can be used, and for example, a bismuth-tellu-based thermoelectric semiconductor material such as P-type bismasterlide and N-type bismasterlide; a telluride-based thermoelectric semiconductor material such as GeTe and PbTe; an antimony-tellu-based thermoelectric semiconductor material; Zinc-antimon _{thermoelectric semiconductor materials such as ZnSb, Zn 3} Sb _2, Zn ₄ Sb ₃ ; silicon-germanium thermoelectric semiconductor materials such as SiGe; _{bismus selenide thermoelectric semiconductor materials such as Bi 2} Se ₃ ; β-FeSi ₂ , CrSi ₂ , MnSi _1.73 , Mg ₂ Si and other VDD-based thermoelectric semiconductor materials; oxide-based thermoelectric semiconductor materials; FeVAL, FeVALSi, FeVTiAl and other Whistler materials, TiS _{2 and} other sulfide-based thermoelectric semiconductor materials Be done.
Among these, a bismuth-tellu-based thermoelectric semiconductor material, a telluride-based thermoelectric semiconductor material, an antimony-tellu-based thermoelectric semiconductor material, or a bismuth selenide-based thermoelectric semiconductor material is preferable.

Further, a bismuth-tellurium thermoelectric semiconductor material such as P-type bismuth telluride or N-type bismuth telluride is more preferable.
As the P-type bismuth telluride, one having a hole as a carrier and a positive Seebeck coefficient, for example, _{represented by Bi X} Te ₃ Sb _2-X is preferably used. In this case, X is preferably 0 <X ≦ 0.8, more preferably 0.4 ≦ X ≦ 0.6. When X is larger than 0 and 0.8 or less, the Seebeck coefficient and the electric conductivity become large, and the characteristics as a P-type thermoelectric element are maintained, which is preferable.
Further, as the N-type bismuth telluride, one having an electron carrier and a negative Seebeck coefficient, for example, _{represented by Bi 2} Te _3-Y Se _Y is preferably used. In this case, Y is preferably 0 ≦ Y ≦ 3 (when Y = 0: Bi ₂ Te ₃ ), and more preferably 0 <Y ≦ 2.7. When Y is 0 or more and 3 or less, the Seebeck coefficient and the electric conductivity become large, and the characteristics as an N-type thermoelectric element are maintained, which is preferable.

The blending amount of the thermoelectric semiconductor material or the thermoelectric semiconductor particles in the thermoelectric semiconductor composition is preferably 30 to 99% by mass. It is more preferably 50 to 96% by mass, and even more preferably 70 to 95% by mass. When the blending amount of the thermoelectric semiconductor particles is within the above range, the Seebeck coefficient (absolute value of the Perche coefficient) is large, the decrease in the electric conductivity is suppressed, and only the thermal conductivity is decreased, so that high thermoelectric performance is exhibited. At the same time, a film having sufficient film strength and flexibility can be obtained, which is preferable.

The average particle size of the thermoelectric semiconductor particles is preferably 10 nm to 200 μm, more preferably 10 nm to 30 μm, still more preferably 50 nm to 10 μm, and particularly preferably 1 to 6 μm. Within the above range, uniform dispersion can be facilitated and the electrical conductivity can be increased.
The thermoelectric semiconductor particles used in the chip of the thermoelectric conversion material are preferably those obtained by pulverizing the above-mentioned thermoelectric semiconductor material to a predetermined size by a fine pulverizer or the like.
The method of pulverizing the thermoelectric semiconductor material to obtain thermoelectric semiconductor particles is not particularly limited, and it may be pulverized to a predetermined size by a known fine pulverizer such as a jet mill, a ball mill, a bead mill, a colloid mill, a roller mill or the like. ..
The average particle size of the thermoelectric semiconductor particles was obtained by measuring with a laser diffraction type particle size analyzer (Mastersizer 3000 manufactured by Malvern), and was used as the median value of the particle size distribution.

Further, the thermoelectric semiconductor particles are preferably annealed (hereinafter, may be referred to as "annealing treatment A"). By performing the annealing treatment A, the crystallinity of the thermoelectric semiconductor particles is improved, and further, the surface oxide film of the thermoelectric semiconductor particles is removed, so that the Seebeck coefficient or the Perche coefficient of the thermoelectric conversion material is increased, and the thermoelectric performance index is increased. Can be further improved. The annealing treatment A is not particularly limited, but before preparing the thermoelectric semiconductor composition, the gas flow rate is controlled so as not to adversely affect the thermoelectric semiconductor particles, and the atmosphere is an inert gas such as nitrogen or argon. Similarly, it is preferably carried out in a reducing gas atmosphere such as hydrogen or under vacuum conditions, and more preferably in a mixed gas atmosphere of an inert gas and a reducing gas. The specific temperature condition depends on the thermoelectric semiconductor particles used, but it is usually preferable to carry out the temperature at a temperature equal to or lower than the melting point of the particles and at 100 to 1500 ° C. for several minutes to several tens of hours.

(Heat resistant resin)
The heat-resistant resin used in the present invention acts as a binder between thermoelectric semiconductor materials (thermoelectric semiconductor particles), can enhance the flexibility of the thermoelectric conversion module, and facilitates the formation of a thin film by coating or the like. The heat-resistant resin is not particularly limited, but when a thin film made of a thermoelectric semiconductor composition is subjected to crystal growth of thermoelectric semiconductor particles by annealing or the like, various factors such as mechanical strength and thermal conductivity as a resin are obtained. A heat-resistant resin that maintains its physical properties without being impaired is preferable.
The heat-resistant resin is preferably a polyamide resin, a polyamideimide resin, a polyimide resin, or an epoxy resin, and has excellent flexibility, because it has higher heat resistance and does not adversely affect the crystal growth of thermoelectric semiconductor particles in the thin film. From this point of view, polyamide resin, polyamideimide resin and polyimide resin are more preferable. When a polyimide film is used as the substrate to be described later, a polyimide resin and a polyamide-imide resin are more preferable as the heat-resistant resin from the viewpoint of adhesion to the polyimide film and the like. In the present invention, the polyimide resin is a general term for polyimide and its precursor.

The heat-resistant resin preferably has a decomposition temperature of 300 ° C. or higher. When the decomposition temperature is within the above range, the flexibility can be maintained without losing the function as a binder even when the thin film made of the thermoelectric semiconductor composition is annealed, as will be described later.

Further, the heat-resistant resin preferably has a mass reduction rate of 10% or less, more preferably 5% or less, and further preferably 1% or less at 300 ° C. by thermogravimetric analysis (TG). .. When the mass reduction rate is within the above range, as will be described later, even when the thin film made of the thermoelectric semiconductor composition is annealed, the flexibility of the chip of the thermoelectric conversion material is maintained without losing its function as a binder. Can be done.

The content of the heat-resistant resin in the thermoelectric semiconductor composition is 0.1 to 40% by mass, preferably 0.5 to 20% by mass, more preferably 1 to 20% by mass, still more preferably 2 to 15%. It is mass%. When the content of the heat-resistant resin is within the above range, it functions as a binder for the thermoelectric semiconductor material, facilitates the formation of a thin film, and obtains a film having both high thermoelectric performance and film strength, and thermoelectric conversion. A resin portion is present on the outer surface of the material chip.

(Ionic liquid)
The ionic liquid that can be contained in the thermoelectric semiconductor composition is a molten salt formed by combining a cation and an anion, and refers to a salt that can exist as a liquid in any temperature range of −50 ° C. or higher and lower than 400 ° C. In other words, the ionic liquid is an ionic compound having a melting point in the range of −50 ° C. or higher and lower than 400 ° C. The melting point of the ionic liquid is preferably −25 ° C. or higher and 200 ° C. or lower, and more preferably 0 ° C. or higher and 150 ° C. or lower. Ionic liquids have features such as extremely low vapor pressure, non-volatility, excellent thermostability and electrochemical stability, low viscosity, and high ionic conductivity. Therefore, as a conductive auxiliary agent, it is possible to effectively suppress a decrease in electrical conductivity between thermoelectric semiconductor materials. Further, since the ionic liquid exhibits high polarity based on the aprotic ionic structure and has excellent compatibility with the heat-resistant resin, the electric conductivity of the thermoelectric conversion material can be made uniform.

As the ionic liquid, known or commercially available ones can be used. For example, nitrogen-containing cyclic cation compounds such as pyridinium, pyrimidinium, pyrazolium, pyrrolidinium, piperidinium, imidazolium and their derivatives; tetraalkylammonium-based amine-based cations and their derivatives; phosphonium, trialkylsulfonium, tetraalkylphosphonium and the like. Hosphin-based cations and their derivatives; cation components such as lithium cations and their derivatives, Cl ⁻ , Br ⁻ , I ⁻ , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , BF ₄ ⁻ , PF ₆ ⁻ , ClO ₄ ⁻ , NO ₃ ⁻ , CH ₃ COO ⁻ , CF ₃ COO ⁻ , CH ₃ SO ₃ ⁻ , CF ₃ SO ₃ ⁻ , (FSO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₂ N ⁻ , (CF ₃ SO ₂ ) ₃ C ⁻ , AsF ₆ ⁻ , SbF ₆ ⁻ , NbF ₆ ⁻ , TaF ₆ ⁻ , F (HF) _n ⁻ , (CN) ₂ N ⁻ , C ₄ F ₉ SO ₃ ⁻ , (C ₂ F ₅ SO ₂ ) Examples thereof include those composed of anionic components such as ₂ N ⁻ , C ₃ F ₇ ^{COO −} , and (CF ₃ SO ₂ ) (CF ₃ CO) N ^−.

Among the above ionic liquids, the cation component of the ionic liquid is a pyridinium cation and its derivatives from the viewpoints of high temperature stability, compatibility with thermoelectric semiconductor materials and resins, and suppression of decrease in electrical conductivity between thermoelectric semiconductor material gaps. , It is preferable to contain at least one selected from the imidazolium cation and its derivatives.

Specific examples of ionic liquids in which the cation component contains a pyridinium cation and a derivative thereof include 4-methyl-butylpyridinium chloride, 3-methyl-butylpyridinium chloride, 4-methyl-hexylpyridinium chloride, and 3-methyl-hexylpyridinium. Chloride, 4-methyl-octylpyridinium chloride, 3-methyl-octylpyridinium chloride, 3,4-dimethyl-butylpyridinium chloride, 3,5-dimethyl-butylpyridinium chloride, 4-methyl-butylpyridiniumtetrafluoroborate, 4- Examples thereof include methyl-butylpyridinium hexafluorophosphate, 1-butylpyridinium bromide, 1-butyl-4-methylpyridinium bromide, 1-butyl-4-methylpyridinium hexafluorophosphate and the like. Of these, 1-butyl-4-methylpyridinium bromide, 1-butylpyridinium bromide, and 1-butyl-4-methylpyridinium hexafluorophosphate are preferable.

Further, as specific examples of the ionic liquid in which the cation component contains an imidazolium cation and a derivative thereof, [1-butyl-3- (2-hydroxyethyl) imidazolium bromide], [1-butyl-3- (2) -Hydroxyethyl) imidazolium tetrafluoroborate], 1-ethyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium bromide, 1-butyl-3-methylimidazolium chloride, 1-hexyl-3 − Methyl imidazolium chloride, 1-octyl-3-methyl imidazolium chloride, 1-decyl-3-methyl imidazolium chloride, 1-decyl-3-methyl imidazolium bromide, 1-dodecyl-3-methyl imidazolium chloride, 1-Tetradecyl-3-methylimidazolium chloride, 1-ethyl-3-methylimidazolium tetrafluoroborolate, 1-butyl-3-methylimidazolium tetrafluoroborobolate, 1-hexyl-3-methylimidazolium tetraflolate Orobolate, 1-ethyl-3-methylimidazolium hexafluorophosphate, 1-butyl-3-methylimidazolium hexafluorophosphate, 1-methyl-3-butylimidazolium methyl sulfate, 1,3-dibutylimidazolium methyl Sulfate and the like can be mentioned. Of these, [1-butyl-3- (2-hydroxyethyl) imidazolium bromide] and [1-butyl-3- (2-hydroxyethyl) imidazolium tetrafluoroborate] are preferable.

The above ionic liquid preferably has an electrical conductivity of ^10-7 S / cm or more. When the ionic conductivity is within the above range, the reduction of the electrical conductivity between the thermoelectric semiconductor materials can be effectively suppressed as a conductive auxiliary agent.

Further, the above-mentioned ionic liquid preferably has a decomposition temperature of 300 ° C. or higher. As long as the decomposition temperature is within the above range, the effect as a conductive auxiliary agent can be maintained even when the thin film made of the thermoelectric semiconductor composition is annealed, as will be described later.

Further, the above-mentioned ionic liquid preferably has a mass reduction rate of 10% or less, more preferably 5% or less, and further preferably 1% or less at 300 ° C. by thermogravimetric analysis (TG). .. As long as the mass reduction rate is within the above range, the effect as a conductive auxiliary agent can be maintained even when the thin film made of the thermoelectric semiconductor composition is annealed, as will be described later.

The blending amount of the ionic liquid in the thermoelectric semiconductor composition is preferably 0.01 to 50% by mass, more preferably 0.5 to 30% by mass, and further preferably 1.0 to 20% by mass. When the blending amount of the ionic liquid is within the above range, the decrease in electrical conductivity is effectively suppressed, and a film having high thermoelectric performance can be obtained.

(Inorganic ionic compound)
The inorganic ionic compound used in the present invention is a compound composed of at least cations and anions. The inorganic ionic compound is solid at room temperature, has a melting point in any temperature in the temperature range of 400 to 900 ° C., and has characteristics such as high ionic conductivity. Therefore, it can be used as a conductive auxiliary agent. It is possible to suppress a decrease in electrical conductivity between thermoelectric semiconductor particles.

As the cation, a metal cation is used.
Examples of the metal cation include alkali metal cations, alkaline earth metal cations, typical metal cations and transition metal cations, and alkali metal cations or alkaline earth metal cations are more preferable.
Examples of the alkali metal cation include Li ⁺ , Na ⁺ , K ⁺ , Rb ⁺ , Cs ^+, Fr ^{+ and the} like.
Examples of the alkaline earth metal cation include Mg ²⁺ , Ca ²⁺ , Sr ²⁺ and Ba ²⁺ .

The anion such ^{as, F -, Cl -, Br} -, I -, OH -, CN -, NO 3 -, NO 2 -, ClO -, ClO 2 -, ClO 3 -, ClO 4 -, CrO 4 2 _{^{-, HSO 4 -, SCN -}} , BF 4 -, PF 6 - , and the like.

As the inorganic ionic compound, known or commercially available ones can be used. For example, cation components such as potassium cation, sodium cation, or lithium cation, chloride ion such as ^{Cl −} , AlCl ₄ ⁻ , Al ₂ Cl ₇ ⁻ , ClO ₄ ⁻ , bromide ion such as ^{Br − , I − and the} like. iodide _ion, ^BF 4 -, PF ₆ ^- fluoride ions, F _{(HF) n,} such as ^- such as halide anions _{^{of, NO 3 -, OH -,}} CN - and the ones mentioned consists the anion component of such Be done.

Among the above-mentioned inorganic ionic compounds, the cationic component of the inorganic ionic compound is potassium from the viewpoints of high temperature stability, compatibility with thermoelectric semiconductor particles and resins, and suppression of decrease in electrical conductivity between thermoelectric semiconductor particle gaps. , Sodium, and lithium are preferably included. Further, the anion component of the inorganic ionic compound preferably contains a halide anion, and more preferably contains at least one selected from ^{Cl −} , Br ⁻ , and I ^−.

Cationic component is, as a specific example of the inorganic ionic compound containing a potassium cation, KBr, KI, KCl, KF , KOH, K 2 CO 3 and the like. Of these, KBr and KI are preferable.
Specific examples of the inorganic ionic compound whose cation component contains a sodium cation include NaBr, NaI, NaOH, NaF, Na ₂ CO _{3 and the} like. Of these, NaBr and NaI are preferable.
Specific examples of the inorganic ionic compound whose cation component contains a lithium cation include LiF, LiOH, and LiNO ₃ . Of these, LiF and LiOH are preferable.

The above-mentioned inorganic ionic compound ^{preferably has an electric conductivity of 10-7} S / cm or more, and more preferably ^10-6 S / cm or more. When the electric conductivity is within the above range, the reduction of the electric conductivity between the thermoelectric semiconductor particles can be effectively suppressed as a conductivity auxiliary agent.

Further, the decomposition temperature of the above-mentioned inorganic ionic compound is preferably 400 ° C. or higher. As long as the decomposition temperature is within the above range, the effect as a conductive auxiliary agent can be maintained even when the thin film made of the thermoelectric semiconductor composition is annealed, as will be described later.

Further, the above-mentioned inorganic ionic compound preferably has a mass reduction rate of 10% or less, more preferably 5% or less, and preferably 1% or less at 400 ° C. by thermogravimetric analysis (TG). More preferred. As long as the mass reduction rate is within the above range, the effect as a conductive auxiliary agent can be maintained even when the thin film made of the thermoelectric semiconductor composition is annealed, as will be described later.

The blending amount of the inorganic ionic compound in the thermoelectric semiconductor composition is preferably 0.01 to 50% by mass, more preferably 0.5 to 30% by mass, and further preferably 1.0 to 10% by mass. .. When the blending amount of the inorganic ionic compound is within the above range, the decrease in electrical conductivity can be effectively suppressed, and as a result, a film having improved thermoelectric performance can be obtained.
When the inorganic ionic compound and the ionic liquid are used in combination, the total content of the inorganic ionic compound and the ionic liquid in the thermoelectric semiconductor composition is preferably 0.01 to 50% by mass. It is preferably 0.5 to 30% by mass, more preferably 1.0 to 10% by mass.

(Method for preparing thermoelectric semiconductor composition)
The method for preparing the thermoelectric semiconductor composition used in the present invention is not particularly limited, and the thermoelectric semiconductor particles, the ions, and the like can be prepared by a known method such as an ultrasonic homogenizer, a spiral mixer, a planetary mixer, a disperser, and a hybrid mixer. If a liquid, the inorganic ionic compound (when used in combination with an ionic liquid), the heat-resistant resin, the other additives if necessary, and a solvent are added and mixed and dispersed to prepare the thermoelectric semiconductor composition. good.
Examples of the solvent include solvents such as toluene, ethyl acetate, methyl ethyl ketone, alcohol, tetrahydrofuran, methylpyrrolidone, and ethyl cellosolve. One of these solvents may be used alone, or two or more of these solvents may be mixed and used. The solid content concentration of the thermoelectric semiconductor composition is not particularly limited as long as the composition has a viscosity suitable for coating.

The chip of the thermoelectric conversion material made of the thermoelectric semiconductor composition is not particularly limited, but is, for example, on a substrate such as glass, alumina, or silicon, or on a substrate on the side on which the sacrificial layer is formed, which will be described later. It can be formed by applying a semiconductor composition to obtain a coating film and drying it. By forming in this way, a large number of chips of thermoelectric conversion material can be easily obtained at low cost.
As a method of applying a thermoelectric semiconductor composition to obtain a chip of a thermoelectric conversion material, a screen printing method, a flexographic printing method, a gravure printing method, a spin coating method, a dip coating method, a die coating method, a spray coating method, a bar coating method, etc. Known methods such as the doctor blade method can be mentioned and are not particularly limited. When the coating film is formed into a pattern, a screen printing method, a slot die coating method, or the like, which enables easy pattern formation using a screen plate having a desired pattern, is preferably used.
Next, the obtained coating film is dried to form chips of the thermoelectric conversion material. As the drying method, conventionally known drying methods such as a hot air drying method, a hot roll drying method, and an infrared irradiation method are adopted. can. The heating temperature is usually 80 to 150 ° C., and the heating time varies depending on the heating method, but is usually several seconds to several tens of minutes.
When a solvent is used in the preparation of the thermoelectric semiconductor composition, the heating temperature is not particularly limited as long as the used solvent can be dried.

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

It is preferable that the chip of the thermoelectric conversion material as a thin film made of the thermoelectric semiconductor composition is further subjected to an annealing treatment (hereinafter, may be referred to as “annealing treatment B”). By performing the annealing treatment B, the thermoelectric performance can be stabilized, and the thermoelectric semiconductor particles in the thin film can be crystal-grown, so that the thermoelectric performance can be further improved. The annealing treatment B is not particularly limited, but is usually carried out under an inert gas atmosphere such as nitrogen or argon, a reducing gas atmosphere, or a vacuum condition in which the gas flow rate is controlled, and the resin and the ionic compound to be used are used. Although it depends on the heat-resistant temperature and the like, it is carried out at 100 to 500 ° C. for several minutes to several tens of hours.

<Board>
As the substrate of the thermoelectric conversion module used in the present invention, that is, as the first substrate and the second substrate, a plastic film that does not affect the decrease in the electric conductivity and the increase in the thermal conductivity of the chip of the thermoelectric conversion material. Is preferably used. Among them, it has excellent flexibility, and even when a thin film made of a thermoelectric semiconductor composition is annealed, the performance of the thermoelectric conversion module can be maintained without thermal deformation of the substrate, and heat resistance and dimensional stability are high. From this point of view, as the plastic film, a polyimide film, a polyamide film, a polyetherimide film, a polyaramid film, and a polyamideimide film are preferable, and a polyimide film is particularly preferable from the viewpoint of high versatility.

The thickness of the plastic film used for the substrate is preferably 1 to 1000 μm, more preferably 10 to 500 μm, still more preferably 20 to 100 μm, from the viewpoint of flexibility, heat resistance and dimensional stability.
Further, the plastic film preferably has a 5% weight loss temperature of 300 ° C. or higher, more preferably 400 ° C. or higher, as measured by thermogravimetric analysis. The heating dimensional change rate measured at 200 ° C. in accordance with JIS K7133 (1999) is preferably 0.5% or less, and more preferably 0.3% or less. JIS K7197 (2012) linear expansion coefficient in the planar direction was measured in accordance with is ^{0.1ppm · ℃ -1 ~50ppm · ℃ -1} , it is 0.1ppm · ℃ ^-1 ~30ppm · ℃ ^-1 Is more preferable.

<Electrode>
The metal material of the first electrode and the second electrode of the thermoelectric conversion module used in the present invention includes gold, nickel, aluminum, rhodium, platinum, chromium, palladium, stainless steel, molybdenum, or any of these metals. Examples include alloys.
The thickness of the electrode layer is preferably 10 nm to 200 μm, more preferably 30 nm to 150 μm, and even more preferably 50 nm to 120 μm. When the thickness of the electrode layer is within the above range, the electric conductivity is high and the resistance is low, and sufficient strength as an electrode can be obtained.

The electrode is formed using the metal material of the electrode. The method of forming the electrode is the same as the method of forming the bonding material receiving layer described above.
Similar to the bonding material layer, the electrode used in the present invention is required to have high conductivity, and the electrode formed by the plating method or the vacuum film forming method can easily realize high conductivity. Therefore, the vacuum vapor deposition method and sputtering can be performed. A vacuum film forming method such as a method, an electrolytic plating method, and a non-electrolytic plating method are preferable. Although it depends on the dimensional and dimensional accuracy requirements of the forming pattern, the pattern can be easily formed through a hard mask such as a metal mask. Further, when the film is formed by the vacuum film forming method, the substrate to be used may be heated while being used for the purpose of improving the adhesion to the substrate to be used, removing water, etc., as long as the characteristics of the substrate are not impaired. good. When the film is formed by the plating method, the film may be formed by the electrolytic plating method on the film formed by the electroless plating method.

In the thermoelectric conversion module of the present invention, the upper and lower surfaces of the chip of the thermoelectric conversion material are bonded to the electrodes facing each other by using a bonding material layer having an elastic modulus of 10 to 3000 MPa, thereby forming the entire thermoelectric conversion module. Since the flexibility is improved and the followability to the heat source surface including the curved shape can be improved, the thermoelectric performance can be further improved as compared with the conventional thermoelectric conversion module having flexibility.

(Manufacturing method of thermoelectric conversion module)
The production of the thermoelectric conversion module of the present invention is a method for producing a thermoelectric conversion module using a plurality of chips of a thermoelectric conversion material.
(A) Step of forming chips of thermoelectric conversion material,
(B) A step of forming the first electrode on the first substrate,
(C) A step of forming a second electrode on the second substrate,
(D) A step of forming a bonding material layer on the first electrode obtained in the step (b).
(E) A step of placing one surface of the chip of the thermoelectric conversion material on the bonding material layer obtained in the step (d).
(F) One surface of the chip of the thermoelectric conversion material placed in the step (e) is joined to the first electrode via the bonding material layer obtained in the step (d). And (g) the other surface of the chip of the thermoelectric conversion material after the step (f) and the second electrode obtained in the step (c) are interposed with a bonding material layer. It is preferable to include a step of joining.
Hereinafter, the step (a) is referred to as a "thermoelectric conversion material chip forming step", the steps (b) and (c) are referred to as an "electrode forming step", and the step (d) is referred to as a "bonding material layer forming step". The step (e) may be referred to as a "thermoelectric conversion material chip mounting step", and the steps (f) and (g) may be referred to as a "joining step".
Hereinafter, the steps included in the present invention will be sequentially described.

<Chip forming process of thermoelectric conversion material>
The chip forming step of the thermoelectric conversion material is the step (a) of the method for manufacturing a thermoelectric conversion module of the present invention. For example, a sacrificial layer to be described later is formed on a base material such as glass described above, and a chip of a thermoelectric conversion material is formed on the obtained sacrificial layer by the method described above. Next, the obtained chips of the thermoelectric conversion material are annealed (according to the conditions of the annealing treatment B), and the chips of the thermoelectric conversion material are peeled off from the sacrificial layer on the base material to form a plurality of pieces. Manufactures chips for thermoelectric conversion materials.
When the sacrificial layer is used, the chips of the thermoelectric conversion material formed on the base material such as glass can be easily peeled off from the glass or the like after the annealing treatment. As the sacrificial layer, a resin such as polymethyl methacrylate or polystyrene, or a release agent such as a fluorine-based release agent or a silicone-based release agent can be used. The formation of the sacrificial layer is not particularly limited, and can be performed by a known method such as a flexographic printing method or a spin coating method.

<Electrode forming process>
The electrode forming step is a step of forming the first electrode on the first substrate in the step (b) in the method for manufacturing the thermoelectric conversion module of the present invention, and in the step (c), the first electrode forming step. This is a step of forming a second electrode on the substrate of 2. For example, it is a step of forming a metal layer on a substrate and processing them into a predetermined pattern to form an electrode.
The above-mentioned substrate is used as the first substrate and the second substrate. Further, the material, thickness, etc. of the substrate are also as described above.
As the first electrode and the second electrode, the above-mentioned electrodes are used. The metal material used for the electrode, the thickness of the electrode layer, the method for forming the electrode, and the like are as described above.

<Joint material layer forming process>
The bonding material layer forming step is the step (d) of the method for manufacturing a thermoelectric conversion module of the present invention, and is a step of forming a bonding material layer on the first electrode. Further, it is included in the step (g) and is a step of forming a bonding material layer on the second electrode.
The bonding material layer is used to bond the chip of the thermoelectric conversion material to the electrode. In the present invention, the above-mentioned conductive adhesive may be used and may be formed on the electrode as the bonding material layer, or may be formed on the above-mentioned bonding material receiving layer.
The thickness of the bonding material layer, the method of coating on the substrate, and the like are as described above.

<Thermoelectric conversion material chip mounting process>
The thermoelectric conversion material chip mounting step is the step (e) of the method for manufacturing a thermoelectric conversion module of the present invention, and one surface of the thermoelectric conversion material chip obtained in the step (a) is pressed. This is a step of placing the bonding material layer on the bonding material layer obtained in the step (d). For example, on the bonding material layer on the electrode of the substrate, one surface of the chip of the P-type thermoelectric conversion material and one surface of the chip of the N-type thermoelectric conversion material are bonded to each other by using a hand portion such as a chip mounter. This is a step of placing the material layer on the upper surface.
The chips of the P-type thermoelectric conversion material and the chips of the N-type thermoelectric conversion material may be arranged in combination with each other depending on the application. For example, "... NPPN ...", "... PNPP". ... ", etc. may be combined randomly. From the viewpoint of theoretically obtaining high thermoelectric performance, it is preferable to arrange a plurality of pairs of P-type thermoelectric conversion material chips and N-type thermoelectric conversion material chips via electrodes.
The method for placing the chip of the thermoelectric conversion material on the bonding material layer is not particularly limited, and a known method is used. For example, one or a plurality of chips of the thermoelectric conversion material may be handled by the above-mentioned chip mounter or the like, aligned with a camera or the like, and placed.
The chip of the thermoelectric conversion material is preferably mounted by a chip mounter from the viewpoint of handleability, mounting accuracy, and mass productivity.

<Joining process>
The joining step is the step (f) of the method for manufacturing a thermoelectric conversion module of the present invention, and one surface of the chip of the thermoelectric conversion material mounted in the step (e) of the above (d). It is a step of joining the first electrode via the bonding material layer obtained in the step, for example, a step of heating the bonding material layer to a predetermined temperature, holding the bonding material layer for a predetermined time, and then returning the bonding material layer to room temperature.
Further, in the step (g) of the method for manufacturing a thermoelectric conversion module of the present invention, the other surface of the chip of the thermoelectric conversion material after the step (f) and the step (c) can be obtained. This is a step of joining the second electrode to the second electrode via a bonding material layer. For example, the other surface of the chip of the P-type thermoelectric conversion material, the other surface of the chip of the N-type thermoelectric conversion material, and the corresponding bonding material layer are interposed, and the second electrode on the second substrate is formed. This is the process of joining.
The heating temperature, holding time, etc., which are the joining conditions, are as described above.

<Matching material receiving layer forming process>
In the method for manufacturing a thermoelectric conversion module of the present invention, it is preferable to further include a step of forming a bonding material receiving layer.
The bonding material receiving layer forming step is a step of providing a bonding material receiving layer on the upper and lower surfaces of the chip of the thermoelectric conversion material obtained in the step (a).
The material and thickness of the bonding material receiving layer, the method of forming on the upper and lower surfaces of the chip of the thermoelectric conversion material, and the like are as described above.
For example, as one preferred embodiment, the method of forming the bonding material receiving layer on the chip of the thermoelectric conversion material is as follows.
After forming the bonding material receiving layer on all the surfaces of the thermoelectric conversion material chip having the upper surface, the lower surface and the side surface, the bonding material formed on the side surface of the thermoelectric conversion material chip among the obtained bonding material receiving layers. The receiving layer is formed by, for example, removing it by a mechanical polishing method, that is, using sandpaper (count 2000) or the like, and removing all or part of it.

According to the method for manufacturing a thermoelectric conversion module of the present invention, it is possible to easily obtain a thermoelectric conversion module having high followability to a heat source surface including a curved surface shape.

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

The elastic modulus of the bonding material layer used in Examples and Comparative Examples, the thermoelectric performance of the thermoelectric conversion module produced in Examples and Comparative Examples, and the followability to curved and planar heat sources are evaluated by the following methods. rice field.

<Elastic modulus of bonding material layer>
For the bonding material layer used in Examples and Comparative Examples, a sample of the bonding material layer having a thickness of 200 μm, a width of 10 mm, and a length of 20 mm was prepared, and a dynamic ultrafine hardness tester (manufactured by Shimadzu Corporation, trade name “DUH-”) was prepared. Using W201S ”), a load-unloading test was performed under the following measurement conditions, and the elastic modulus was calculated from the slope of the obtained unloading curve.
<Dynamic ultra-micro hardness tester measurement conditions>
Indenter: Triangular pyramid indenter Ridge angle 115 °
Test mode: Load-unload mode Test force: 1mN
Load speed: 0.142mN / sec
Retention time: 5 sec
Measurement temperature: 25 ° C

<Thermoelectric performance evaluation>
(Evaluation of thermoelectric performance of curved heat source)
(A) Evaluation of Electrical Resistance of Thermoelectric Conversion Module The obtained thermoelectric conversion module is wound around a cylinder (φ75 mm, length 200 mm, material: acrylic resin) as a curved heat source heated to 50 ° C. by winding a flexible heater. By using a heat sink having flexibility that follows the cylinder, a temperature difference is applied to the upper and lower surfaces of the thermoelectric conversion module, and the module resistance R (electrical resistance) between the extraction electrodes of the thermoelectric conversion module is set to a low resistance measuring device ( It was measured in an environment of 25 ° C. × 50% RH using a model name: RM3545) manufactured by Hioki Electric Co., Ltd.

(B) Output voltage and maximum output evaluation of thermoelectric conversion module (curved surface)
In (a), the output voltage V (electromotive force) between the output extraction electrodes of the thermoelectric conversion module was set to 25 ° C. × 50% RH using a digital high tester (manufactured by Hioki Electric Co., Ltd., model name: 3801-50). Measured in the environment.
Further, the maximum output P (= V ² / 4R) was calculated from the obtained module resistance R and output voltage V.

(Evaluation of thermoelectric performance of flat heat source)
(C) Evaluation of Electrical Resistance of Thermoelectric Conversion Module The obtained thermoelectric conversion module is mounted on a flat plate (material: acrylic resin) as a flat heat source heated to 50 ° C. by winding a flexible heater, and the thermoelectric conversion module is mounted on the flat plate (material: acrylic resin). By providing a heat sink in the module, a temperature difference is applied to the upper and lower surfaces of the thermoelectric conversion module, and the module resistance R (electrical resistance) between the extraction electrodes of the thermoelectric conversion module is set to a low resistance measuring device (manufactured by Hioki Electric Co., Ltd., model name: It was measured using RM3545) in an environment of 25 ° C. × 50% RH.

(D) Output voltage and maximum output evaluation of thermoelectric conversion module (plane)
In (c), the output voltage V (electromotive force) between the output extraction electrodes of the thermoelectric conversion module was set to 25 ° C. × 50% RH using a digital high tester (manufactured by Hioki Electric Co., Ltd., model name: 3801-50). Measured in the environment.
Further, the maximum output P (= V ² / 4R) was calculated from the obtained module resistance R and output voltage V.

<Evaluation of followability of thermoelectric conversion module to curved surface heat source>
The maximum output of the thermoelectric conversion module when wound around a curved heat source obtained in the evaluations of (a) and (b) and the flat heat source obtained in the evaluations of (c) and (d). From the maximum output of the thermoelectric conversion module, the followability of the thermoelectric conversion module to the curved surface heat source was evaluated according to the following criteria.
A: When the decrease in the maximum output of the thermoelectric conversion module when mounted on a curved surface heat source is less than 50% of the maximum output of the thermoelectric conversion module when mounted on a flat surface heat source B: Thermoelectric conversion when mounted on a flat surface heat source When the decrease in the maximum output of the thermoelectric conversion module when mounted on a curved surface heat source is 50% or more and less than 80% with respect to the maximum output of the module C: Curved surface heat source with respect to the maximum output of the thermoelectric conversion module when mounted on a flat surface heat source When the decrease in the maximum output of the thermoelectric conversion module when mounted on is 80% or more

(Example 1)
(1) Preparation of thermoelectric semiconductor composition (production of thermoelectric semiconductor particles)
_{P-type bismuth tellurium Bi 0.4} Te ₃ Sb _1.6 (manufactured by High Purity Chemical Laboratory, particle size: 90 μm), which is a bismuth-tellurium thermoelectric semiconductor material, is used in a planetary ball mill (manufactured by Fritsch Japan, Premium line P). Thermoelectric semiconductor particles T1 having an average particle size of 2.5 μm were produced by pulverizing in an air atmosphere using −7).
_{Further, N-type bismuth tellurium Bi 2} Te ₃ (manufactured by High Purity Chemical Laboratory, particle size: 90 μm), which is a bismuth-tellurium-based thermoelectric semiconductor material, is subjected to thermoelectric semiconductor particles having an average particle size of 2.5 μm by the same method as described above. T2 was prepared.
The particle size distribution of the thermoelectric semiconductor particles T1 and T2 obtained by pulverization was measured by a laser diffraction type particle size analyzer (Mastersizer 3000 manufactured by Malvern).
(Preparation of coating liquid for thermoelectric semiconductor composition)
Coating liquid (P)
83.3 parts by mass of particles T1 of P-type bismasterlide Bi _0.4 Te _3.0 Sb _1.6 obtained above, polyamide-imide as a heat-resistant resin (manufactured by Arakawa Chemical Industry Co., Ltd., product name: Composelan AI301, Solvent: N-methylpyrrolidone, solid content concentration: 18% by mass) 2.7 parts by mass, and N-butylpyridinium bromide 14.0 parts by mass as an ionic liquid are mixed and dispersed in a coating liquid (P). ) Was prepared.
Coating liquid (N)
91.6 parts by mass of the particles T2 of the N-type bismuth sterlide Bi ₂ Te ₃ obtained above, polyamide-imide as a heat-resistant resin (manufactured by Arakawa Chemical Industry Co., Ltd., product name: composelan AI301, solvent: N-methylpyrrolidone, solid) A coating liquid (N) composed of a thermoelectric semiconductor composition in which 3.6 parts by mass (concentration: 18% by mass) and 4.8 parts by mass of 1-butylpyridinium bromide as an ionic liquid were mixed and dispersed was prepared.
(2) Preparation of Chip for Thermoelectric Conversion Material Polymethylmethylmethacrylate resin (PMMA) (manufactured by Sigma Aldrich Co., Ltd., trade name: polymethacrylic acid) as a sacrificial layer on a glass substrate (soda lime glass) having a thickness of 0.7 mm. A polymethylmethyl methacrylate resin solution in which methyl) was dissolved in toluene and having a solid content concentration of 10% by mass was formed into a film by a spin coating method so that the thickness after drying was 10.0 μm.
Next, the coating liquid (P) prepared in (1) above was applied onto the sacrificial layer via a metal mask by a screen printing method, and dried at a temperature of 120 ° C. for 7 minutes in an air atmosphere (thickness). : 350 μm). Then, by pressurizing at 250 ° C. at 110 MPa for 10 minutes in an atmospheric atmosphere, a thin film composed of a thermoelectric semiconductor composition containing particles of a P-type thermoelectric semiconductor material having a thickness of 200 μm was formed. The temperature of the obtained thin film was raised at a heating rate of 5 K / min in an atmosphere of a mixed gas of hydrogen and argon (hydrogen: argon = 3% by volume: 97% by volume), and held at 430 ° C. for 1 hour. The thin film is annealed to grow particles of the thermoelectric semiconductor material into crystals, and the upper and lower surfaces are 1.65 mm × 1.65 mm and the thickness is 200 μm, including _{P-type bismuth telluride Bi 0.4} Te ₃ Sb _1.6. A rectangular P-type thermoelectric conversion material chip was obtained.
Further, the coating liquid (N) prepared in the above (1) was changed, and the thin film was annealed under an atmospheric atmosphere of 250 ° C. for 37 MPa and 360 ° C. for 1 hour in a mixed gas atmosphere of hydrogen and argon. A rectangular N with an upper and lower surface of 1.65 mm x 1.65 mm and a thickness of 200 μm (thickness before pressurization: 390 μm), including the N-type bismuth _{sterlide Bi 2} Te _{3, respectively.} A chip of type thermoelectric conversion material was obtained.

(3) Formation of bonding material receiving layer All the chips of P-type and N-type thermoelectric conversion materials after annealing are peeled off from the glass substrate, and all the chips of P-type and N-type thermoelectric conversion materials are subjected to electroless plating. A nickel layer (thickness: 3 μm) and a gold layer (thickness: 40 nm) were laminated in this order on the surface as a bonding material receiving layer.
Next, the bonding material receiving layer on the side surface of the chip of P-type and N-type thermoelectric conversion material is machine-polished, that is, sandpaper (count 2000) is used so that the chip has a size of 1.5 mm × 1.5 mm. To obtain chips of P-type and N-type thermoelectric conversion materials having bonding material receiving layers only on the upper and lower surfaces. In addition, in order to completely remove the bonding material receiving layer, a part of the side wall of the chip of the P-type and N-type thermoelectric conversion material was also polished.

(4) Electrode formation First, prepare a polyimide film substrate (manufactured by Ube Eximo Co., Ltd., product name: Iupicel N, polyimide substrate, thickness: 12.5 μm, copper foil, thickness: 12 μm) in which copper foil is attached to both sides. Then, a nickel layer (thickness: 3 μm) and a gold layer (thickness: 40 nm) were laminated in this order on the copper foil of the polyimide film substrate by electroless plating, and then an electrode pattern (5.5) was laminated on only one side. × 1.75 mm, 18 pieces, distance between adjacent electrodes: 2 mm, 6 columns × 3 rows) were formed to prepare a substrate having electrodes (first substrate having first electrodes, hereinafter, “1st substrate”. It is sometimes called "first electrode substrate").
Similarly, a substrate in which electrodes are arranged in a pattern is produced so that a π-type thermoelectric conversion module can be obtained when the first electrode substrate is bonded (second substrate having a second electrode, hereinafter referred to as “second electrode”. Sometimes called "board"). The substrate, the electrode material, the dimensions including the thickness, and the like were the same as those of the first electrode substrate.

<Manufacturing of thermoelectric conversion module>
Using the P-type and N-type thermoelectric conversion material chips having the bonding material receiving layer only on the upper and lower surfaces obtained above, the P-type and N-type thermoelectric conversion material chips bonded to the electrodes via the bonding material layer are 18 respectively. A pair of π-type thermoelectric conversion element modules was manufactured as follows.

<Mounting and assembly of thermoelectric conversion material chips>
A flexible conductive adhesive (manufactured by Cemedyne, SX-ECA48, conductive material: silver particles, resin: silicone resin, elastic modulus: 225 MPa (25 ° C.)) is used as a bonding material layer on the electrode of the first electrode substrate. , A bonding material layer (thickness before curing: 50 μm) was formed by stencil printing.
Next, on the bonding material layer, one surface having the bonding material receiving layers of the P-type and N-type thermoelectric conversion material chips obtained above is bent at a distance of 2 mm between the chips in the extending direction of the bent portion. P-type and N-type and N-type and N-type and N-type and N-type and N Chips of the type thermoelectric conversion material were mounted on the electrodes of the first electrode substrate, respectively. At this time, the distance between the chips in the extending direction of the bent portion is 1.33 times the length of the chips in the extending direction of the bent portion.
Further, the flexible conductive adhesive is stencil-printed (thickness before curing: 50 μm) as the bonding material layer on the other surface of the P-type and N-type thermoelectric conversion material chips having the bonding material receiving layers, respectively. The obtained bonding material layer and the electrode of the second electrode substrate are bonded together and heated at 100 ° C. for 1 hour to obtain chips and a second electrode of P-type and N-type thermoelectric conversion materials having a bonding material receiving layer. A thermoelectric conversion module was obtained by joining the counter electrode, which is an electrode of the substrate, via a bonding material layer (thickness after heating: 30 μm) and assembling.

According to the thermoelectric performance evaluation described above, a temperature difference was applied to the upper and lower surfaces of the thermoelectric conversion module, and the module resistance R and the output voltage V were measured. The maximum output P (μW) was calculated (P = V ² / 4R) from the module resistance R and the obtained output voltage V. The results are shown in Table 1.

(Example 2)
A thermoelectric conversion module was produced in the same manner as in Example 1 except that the distance between the chips in the extending direction of the bent portion of the P-type and N-type thermoelectric conversion materials was set to 1 mm. With respect to the obtained thermoelectric conversion module, a temperature difference was applied to the upper and lower surfaces of the thermoelectric conversion module in the same manner as in Example 1, and the module resistance R and the output voltage V were measured. Next, the maximum output P (= V ² / 4R) was calculated from the module resistance R and the obtained output voltage V. The results are shown in Table 1. At this time, the distance between the chips in the extending direction of the bent portion is 0.667 times the length of the chips in the extending direction of the bent portion.

(Example 3)
A thermoelectric conversion module was produced in the same manner as in Example 1 except that the distance between the chips in the extending direction of the bent portion of the P-type and N-type thermoelectric conversion materials was set to 0.2 mm. With respect to the obtained thermoelectric conversion module, a temperature difference was applied to the upper and lower surfaces of the thermoelectric conversion module in the same manner as in Example 1, and the module resistance R and the output voltage V were measured. Next, the maximum output P (= V ² / 4R) was calculated from the module resistance R and the obtained output voltage V. The results are shown in Table 1. At this time, the distance between the chips in the extending direction of the bent portion is 0.133 times the tip length in the extending direction of the bent portion.

(Example 4)
In Example 1, a conductive adhesive (manufactured by Nihon Handa Co., Ltd., ECA300, conductive material: silver particles, resin: epoxy resin, elastic modulus: 430 MPa (25 ° C.)) was used for the bonding material layers on the mounting side and the assembling side. A thermoelectric conversion module was produced in the same manner as in Example 1 except that it was heat-cured at 200 ° C. for 1 hour (thickness of the bonding material layer: 30 μm). With respect to the obtained thermoelectric conversion module, a temperature difference was applied to the upper and lower surfaces of the thermoelectric conversion module in the same manner as in Example 1, and the module resistance R and the output voltage V were measured. Next, the maximum output P (= V ² / 4R) was calculated from the module resistance R and the obtained output voltage V. The results are shown in Table 1.

(Example 5)
In Example 1, a conductive adhesive (manufactured by Muromachi Chemical Co., Ltd., EPS-110A, conductive material: silver particles, resin: epoxy resin, elastic modulus: 14 MPa (25 ° C.)) was applied to the bonding material layers on the mounting side and the assembling side. A thermoelectric conversion module was produced in the same manner as in Example 1 except that it was heat-cured at 180 ° C. for 0.5 hours (thickness of bonding material layer: 30 μm). With respect to the obtained thermoelectric conversion module, a temperature difference was applied to the upper and lower surfaces of the thermoelectric conversion module in the same manner as in Example 1, and the module resistance R and the output voltage V were measured. Next, the maximum output P (= V ² / 4R) was calculated from the module resistance R and the obtained output voltage V. The results are shown in Table 1.

(Comparative Example 1)
In Example 1, a thermoelectric conversion module was produced in the same manner as in Example 1 except that solder was used for the bonding material layer on the mounting side. With respect to the obtained thermoelectric conversion module, a temperature difference was applied to the upper and lower surfaces of the thermoelectric conversion module in the same manner as in Example 1, and the module resistance R and the output voltage V were measured. Next, the maximum output P (= V ² / 4R) was calculated from the module resistance R and the obtained output voltage V. The results are shown in Table 1.

(Comparative Example 2)
In Example 1, a thermoelectric conversion module was produced in the same manner as in Example 1 except that solder was used for the bonding material layer on the assembly side. With respect to the obtained thermoelectric conversion module, a temperature difference was applied to the upper and lower surfaces of the thermoelectric conversion module in the same manner as in Example 1, and the module resistance R and the output voltage V were measured. Next, the maximum output P (= V ² / 4R) was calculated from the module resistance R and the obtained output voltage V. The results are shown in Table 1.

(Comparative Example 3)
In Example 1, a thermoelectric conversion module was produced in the same manner as in Example 1 except that solder was used for the bonding material layers on the mounting side and the assembling side. With respect to the obtained thermoelectric conversion module, a temperature difference was applied to the upper and lower surfaces of the thermoelectric conversion module in the same manner as in Example 1, and the module resistance R and the output voltage V were measured. Next, the maximum output P (= V ² / 4R) was calculated from the module resistance R and the obtained output voltage V. The results are shown in Table 1.

(Comparative Example 4)
In Example 1, a flexible conductive adhesive (manufactured by Muromachi Chemical Co., Ltd., K-72-1 LV, conductive material: silver particles, resin: epoxy resin, elastic modulus: 3490 MPa) was applied to the bonding material layer on the mounting side and the assembling side. A thermoelectric conversion module was produced in the same manner as in Example 1 except that 25 ° C.)) was used. With respect to the obtained thermoelectric conversion module, a temperature difference was applied to the upper and lower surfaces of the thermoelectric conversion module in the same manner as in Example 1, and the module resistance R and the output voltage V were measured. Next, the maximum output P (= V ² / 4R) was calculated from the module resistance R and the obtained output voltage V. The results are shown in Table 1.

When the heat source is not a flat surface but a curved surface, in Examples 1 to 5 in which a bonding material layer having an elastic modulus in a specific range of the present invention is provided on the mounting side and the assembling side on the electrode, the specification is not specified on the electrode. It can be seen that the followability is excellent and the maximum output of 3.0 to 3.9 times can be obtained as compared with Comparative Examples 1 to 4 in which the bonding material layer having an elastic modulus is provided on the mounting side and / or the assembling side.

The thermoelectric conversion module of the present invention has excellent followability even if the heat source has a curved surface shape or the like, and therefore has higher thermoelectric performance than conventional products having insufficient followability.
Therefore, the thermoelectric conversion module of the present invention is particularly capable of exhausting heat from pipes and the like drained for cooling purposes in factories and the like, exhausting heat from piping such as boilers, exhausting heat from combustion gas exhausting devices of automobiles, and the like. It is conceivable to attach it to a heat source having a curved shape or the like and apply it to a power generation application that converts a temperature difference into electricity.

1A, 1B: Thermoelectric conversion module 2a: First substrate 2b: Second substrate 3a: First electrode 3b: Second electrode 4: P-type thermoelectric conversion material chip 5: N-type thermoelectric conversion material chip 6 : Joining material layer 7: Joining material receiving layer

Claims (14)

A first substrate having a first electrode, a second substrate having a second electrode, a chip of a thermoelectric conversion material made of a thermoelectric semiconductor composition, one surface of the chip of the thermoelectric conversion material, and the first. A thermoelectric conversion module including an electrode 1 and a bonding material layer for bonding the other surface of the chip of the thermoelectric conversion material and the second electrode, respectively, wherein the bonding material layer is made of resin and conductive. A thermoelectric conversion module made of a conductive adhesive containing a material and having an elastic coefficient of 10 to 3000 MPa at 25 ° C. after curing of the bonding material layer. The thermoelectric conversion module according to claim 1, wherein the resin is selected from an epoxy resin, a silicone resin, a polyimide resin, and a polyurethane resin. The conductive material contains metal particles, and the metal particles are one or two selected from silver particles, nickel particles, gold particles, indium particles, tin particles, aluminum particles, palladium particles, titanium particles and copper particles. The thermoelectric conversion module according to claim 1, which is one kind or a mixture of two or more kinds selected from silver particles, nickel particles, and copper particles which are the above-mentioned mixtures. The distance between the chips of the thermoelectric conversion material adjacent to each other in the extending direction (direction orthogonal to the bending direction) of the bent portion of the thermoelectric conversion module is the length of the chips of the thermoelectric conversion material in the extending direction of the bent portion. The thermoelectric conversion module according to claim 1, which is 0.1 or more and less than 3 times. The thermoelectric conversion module according to claim 1, wherein the elastic modulus is 10 to 1000 MPa. The thermoelectric conversion module according to any one of claims 1 to 5, wherein the bonding material layer has a thickness of 10 to 1000 μm. The thermoelectric conversion module according to any one of claims 1 to 6, further comprising a bonding material receiving layer containing a metal material between the chip of the thermoelectric conversion material and the bonding material layer. The thermoelectric conversion module according to claim 7, wherein the metal material is at least one selected from an alloy containing gold, silver, rhodium, platinum, chromium, palladium, tin, nickel, and any of these metal materials. .. The thermoelectric conversion module according to claim 7 or 8, wherein the bonding material receiving layer has a thickness of 10 nm to 50 μm. The thermoelectric conversion module according to any one of claims 1 to 9, wherein the thermoelectric semiconductor composition contains one or both of a thermoelectric semiconductor material, a heat-resistant resin, an ionic liquid and an inorganic ionic compound. The thermoelectric conversion module according to claim 10, wherein the heat-resistant resin is a polyimide resin, a polyamide resin, a polyamide-imide resin, or an epoxy resin. The thermoelectric conversion module according to claim 10, wherein the thermoelectric semiconductor material is a bismuth-tellurium-based thermoelectric semiconductor material, a tellurium-based thermoelectric semiconductor material, an antimony-tellurium-based thermoelectric semiconductor material, or a bismuth selenide-based thermoelectric semiconductor material. The thermoelectric conversion module according to claim 12, wherein the bismuth-tellurium-based thermoelectric semiconductor material is P-type bismuth tellurium, N-type bismuth tellurium, or Bi ₂ Te _3. Claims 1 to 1, wherein the first substrate and the second substrate are made of a plastic film, and the plastic films are independently a polyimide film, a polyamide film, a polyetherimide film, a polyaramid film, or a polyamideimide film. 13. The thermoelectric conversion module according to any one of 13.

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