JP2022157771A - Electrode for thermoelectric conversion module and thermoelectric conversion module using the same - Google Patents

Abstract

To provide an electrode for a thermoelectric conversion module that suppresses leakage of molten solder during joining and does not cause a short circuit between the chips of adjacent thermoelectric conversion materials.SOLUTION: In an electrode for a thermoelectric conversion module in which the chip of a P-type thermoelectric conversion material and the chip of an N-type thermoelectric conversion material, which are separated from each other, are joined to electrodes via a solder material, and the electrode has a structure portion in a region where the chip of the P-type thermoelectric conversion material and the chip of the N-type thermoelectric conversion material are joined.SELECTED DRAWING: Figure 1

Description

The present invention relates to a thermoelectric conversion module electrode and a thermoelectric conversion module using the same.

2. Description of the Related Art Conventionally, as one means of effective utilization of energy, there is a device that directly and mutually converts heat energy and electric energy by means of a thermoelectric conversion module having a thermoelectric effect such as the Seebeck effect or the Peltier effect.
As the thermoelectric conversion module, use of a so-called π-type thermoelectric conversion element is known. The π-type has a pair of electrodes spaced apart from each other on a substrate, for example, a P-type thermoelectric element on one electrode and an N-type thermoelectric element on the other electrode, also spaced apart from each other. , by connecting the top surfaces of both thermoelectric elements to electrodes on the opposing substrate.
Under such circumstances, in the manufacture of the thermoelectric conversion module, usually, the P-type thermoelectric elements and the N-type thermoelectric elements are independently bonded to the electrodes on the substrate via a bonding material. When a solder material or the like is used as the bonding material, during bonding by heating and pressurization such as reflow, for example, when the solder material arranged facing the lower surfaces of the P-type thermoelectric element and the N-type thermoelectric element is melted , the molten solder flows not only due to surface tension but also due to the pressure applied to the P-type thermoelectric element and the N-type thermoelectric element and their own weight, so that the molten solder faces the P-type thermoelectric element and the N-type thermoelectric element Leakage from the junction (junction region) with the electrode, and finally the side surface of the adjacent P-type thermoelectric element and the side surface of the N-type thermoelectric element are physically connected, so that the P-type thermoelectric element and the N-type thermoelectric element Electrical shorts can occur between elements, degrading thermoelectric performance.
Patent Literature 1 discloses a thermoelectric conversion module having a configuration of π-type thermoelectric conversion elements and having electrodes in a specific shape.

JP 2014-138135 A

As the electrodes constituting the thermoelectric conversion module of Patent Document 1, the electrode on one side is connected to the thermoelectric semiconductor via a solder material, and the electrode is a flat plate that is commonly used in the field of thermoelectric conversion. However, there is no description or suggestion regarding the occurrence of specific problems due to solder leakage from joints. In addition, the electrode on the other side has a structure having a bump-like projection so as to be in contact with the thermoelectric semiconductor. , and what kind of effect is exhibited when they are mediated by a solder material.

The present invention has been made in view of such circumstances, and provides an electrode for a thermoelectric module that suppresses leakage of molten solder during joining and does not cause a short circuit between chips of adjacent thermoelectric conversion materials, and a thermoelectric module using the same. An object of the present invention is to provide a conversion module.

The inventors of the present invention have made intensive studies to solve the above problems, and as a result, in the junction between the thermoelectric conversion material chip and the electrode via the solder material, which constitutes the thermoelectric conversion module, the area of the electrode junction By providing the structure part in the structure, the occurrence of short circuit between the side surface of the chip of the adjacent P-type thermoelectric conversion material and the side surface of the chip of the N-type thermoelectric conversion material due to solder leakage when the solder material melts is suppressed. and completed the present invention.
That is, the present invention provides the following [1] to [5].
[1] An electrode for a thermoelectric conversion module in which a chip of a P-type thermoelectric conversion material and a chip of an N-type thermoelectric conversion material that are separated from each other are joined to an electrode via a solder material, wherein the electrode is the P-type thermoelectric conversion An electrode for a thermoelectric conversion module, comprising a structural body in a region that joins the chip of material and the chip of N-type thermoelectric conversion material.
[2] The thermoelectric conversion according to [1] above, wherein the shape of the structure part is selected from rectangular parallelepiped, cubic, cylindrical, prismatic, pyramidal, conical, truncated pyramidal, and truncated conical. Electrodes for modules.
[3] The electrode for a thermoelectric conversion module according to [1] or [2] above, wherein the material of the structure portion is selected from gold, silver, copper, nickel, and aluminum.
[4] The electrode for a thermoelectric conversion module according to any one of [1] to [3] above, wherein the structure portion is provided with a space in the region.
[5] A thermoelectric conversion module, wherein the electrode for thermoelectric conversion module according to any one of [1] to [4] is used in a π-type thermoelectric conversion element.

Advantageous Effects of Invention According to the present invention, it is possible to provide a thermoelectric module electrode and a thermoelectric conversion module using the same, which suppress leakage of molten solder during joining and prevent short circuits from occurring between adjacent thermoelectric conversion material chips.

FIG. 1 is a configuration diagram for explaining an example of the shape of the electrode of the present invention. FIG. 2 is a diagram for explaining an example of a state before and after joining the electrode of the present invention, a chip of thermoelectric conversion material, and a solder material layer used for joining. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a cross-sectional view for explaining an example of the configuration of a thermoelectric conversion module including the thermoelectric module electrode of the present invention;

[Electrodes for thermoelectric conversion modules]
The thermoelectric conversion module electrode of the present invention is a thermoelectric conversion module electrode in which a P-type thermoelectric conversion material chip and an N-type thermoelectric conversion material chip that are separated from each other are joined to the electrode via a solder material, is characterized by comprising a structure portion in a region where the chip of the P-type thermoelectric conversion material and the chip of the N-type thermoelectric conversion material are joined.
In the electrode for a thermoelectric conversion module of the present invention, the electrode itself is provided with a structure portion in the region of the electrode junction at the junction between the chip of the thermoelectric conversion material and the electrode via the solder material, which constitutes the thermoelectric conversion module. As a result, it is possible to suppress the occurrence of a short circuit between the side surface of the adjacent P-type thermoelectric conversion material chip and the side surface of the N-type thermoelectric conversion material chip due to solder leakage when the solder material melts. Therefore, when the electrode is used as an electrode of a thermoelectric conversion module, it leads to improvement in production yield and prevention of deterioration in thermoelectric performance.
In the present specification, the term “electrode” may or may not be integrated as long as the electrode is provided with a structure portion.

FIG. 1 is a configuration diagram for explaining an example of the shape of the electrode of the present invention, and FIG. 1(a) is a plan view showing an electrode 3 having a structure portion 3c on a base electrode 3a. The area within the dotted line frame represents a junction (joint area) 6p between the electrode and the tip of the P-type thermoelectric conversion material and a junction (joint area) 6n between the electrode and the tip of the N-type thermoelectric conversion material. Four structural body portions 3c are arranged in each of the portions so as to be evenly distributed with respect to the center of each joint portion. (b) is a cross-sectional view of the electrode 3 taken along line A-A' in (a).

FIG. 2 is a diagram for explaining an example of a state before and after joining the electrode of the present invention, a chip of a thermoelectric conversion material, and a solder material layer used for joining. A cross section showing a mode in which a chip 4p of a P-type thermoelectric conversion material and a chip 4n of an N-type thermoelectric conversion material are placed on a solder material layer 5 (before solidification) made of a paste containing a solder material on an electrode 3 provided with 3c. It is a diagram. (b) is a cross-sectional view showing a state after heating and cooling the solder material layer 5 (before solidification) in (a), and the solder material layer 5 (before solidification) melts each joint (joint region). It spreads so as to fill it up, and finally, due to the presence of the structure part 3c, the spread almost stops within each joint (joint region), and becomes a solder material layer 5' (after solidification), P-type thermoelectric conversion The material chip 4p and the N-type thermoelectric conversion material chip 4n are joined to the electrodes on the lower surface side of each in such a manner that solder leakage is suppressed. In addition, (c) shows that the upper surfaces of the P-type thermoelectric conversion material chip 4p and the N-type thermoelectric conversion material chip 4n in (b) are electrodes provided with a structure portion 3c on a base electrode 3b serving as a counter electrode. 3 is a cross-sectional view showing a state in which a solder material layer 5' (after solidification) is interposed in between. As a result, the electrodes on the lower surface side and the upper surface side of the tip 4p of the P-type thermoelectric conversion material and the tip 4n of the N-type thermoelectric conversion material are joined.

The shape of the structural body provided in the electrode of the present invention is such that the thermoelectric performance inherent in the electrode can be maintained, leakage of molten solder from the solder material is suppressed, and the solder material reaches the side surfaces of the chips of the adjacent thermoelectric conversion materials. Although there is no particular limitation unless there is a From the viewpoint of performance and high-density mounting, it is selected from a rectangular parallelepiped shape and a cubic shape. In addition, the thickness of the structure portion will be described later, but from the viewpoint of supporting the thermoelectric conversion material chip uniformly and stably and preventing the formation of gaps between the thermoelectric conversion material chip and the solder material layer, a plurality of structures Each of the parts is preferably substantially identical.
The number of structural parts is not particularly limited, and at least one is sufficient. However, the number, size and arrangement of the structural parts may be appropriately adjusted according to the area of the joint (joint region).
As one aspect, it is preferable that a plurality of structural body portions be provided at intervals within the joint portion. The plurality of structural body parts may be arranged at any position of the joint, but from the viewpoint of making it easier to uniformly suppress solder leakage to the outside of the joint due to solder flow when the solder material is melted. Therefore, it is preferable to arrange them evenly at predetermined intervals from the center of the joint to the outer side.
By setting the number, size and arrangement of the structure parts as described above, it is possible to easily suppress solder leakage to the outside of the joint due to solder flow when the solder material is melted.

Although the material of the structure portion is not particularly limited, it is preferable to use a conductive material, more preferably a metal material, from the viewpoint of suppressing deterioration in electrical connectivity. The metal material is not particularly limited, and includes gold, silver, copper, nickel, aluminum, rhodium, platinum, chromium, palladium, molybdenum, and alloys containing any of these metals. Alternatively, it may be a composition containing a resin and a conductive material.
Among these, it is preferably selected from gold, silver, copper, nickel and aluminum. From the viewpoint of bondability with the material of the base electrode, it is more preferable to use the same material as the base electrode material described below.
The thickness of the structure portion is not particularly limited, but is appropriately adjusted depending on the upper and lower surfaces of the thermoelectric conversion material chip, that is, the area of the joint (joint region) and/or the amount of the solder material, but is usually 1 to 1. 100 μm, preferably 5 to 50 μm, more preferably 7 to 35 μm.

The planar shape of the electrode serving as the base including the structure portion is not particularly limited, and may be rectangular, circular, elliptical, or the like. From the standpoints of ease of manufacture, high-density mounting, and thermoelectric performance, it is preferably rectangular.

The metal material of the base electrode other than the structure part of the electrode for the thermoelectric conversion module used in the present invention is the same as the conductive material used for the structure part described above, and includes gold, silver, copper, nickel, Examples include aluminum, rhodium, platinum, chromium, palladium, molybdenum, and alloys containing any of these metals.
A paste material containing a solvent or a resin component may be used in addition to the metal material. When using a paste material, it is preferable to remove the solvent and the resin component by firing or the like. Silver paste and aluminum paste are preferable as the paste material. The firing temperature is usually 100 to 280° C. for 0.5 to 2 hours.

The electrode of the present invention is formed using the metal material used for the structure portion and the metal material for the base electrode.

As a method for forming a base electrode, a method of processing a substrate into a predetermined pattern shape by a known physical treatment or chemical treatment mainly based on photolithography, or a combination thereof, or , screen printing method, stencil printing method, ink jet method and the like to directly form a pattern of the electrode layer.
Methods for forming electrodes without a pattern include PVD (physical vapor deposition) such as vacuum deposition, sputtering, and ion plating, or CVD (chemical vapor deposition) such as thermal CVD and atomic layer deposition (ALD). vapor phase growth method), or various coatings such as dip coating method, spin coating method, spray coating method, gravure coating method, die coating method, doctor blade method, wet process such as electrodeposition method, silver A salt method, an electrolytic plating method, an electroless plating method, lamination of metal foil, and the like can be mentioned, and the method is appropriately selected according to the material of the substrate.
The thickness of the base electrode layer is preferably 10 nm to 200 μm, more preferably 30 nm to 150 μm, still more preferably 50 nm to 120 μm. If the thickness of the base electrode layer is within the above range, the electrical conductivity is high and the resistance is low, and sufficient strength as an electrode can be obtained.

As a method for forming the structure part provided in the electrode, a predetermined pattern shape is formed on the above-described base electrode by a known physical treatment or chemical treatment mainly based on photolithography, or by using them in combination. Alternatively, a method of forming a pattern of the structure part directly on the base electrode by a screen printing method, a stencil printing method, an inkjet method, or the like.
As for the method of forming the structure portion where no pattern is formed, PVD (Physical Vapor Deposition) such as vacuum deposition, sputtering, ion plating, etc., or thermal deposition is used in the same manner as the method of forming the base electrode. Dry film formation methods such as CVD (chemical vapor deposition) such as CVD and atomic layer deposition (ALD), or dip coating methods, spin coating methods, spray coating methods, gravure coating methods, die coating methods, doctor blade methods, etc. various coatings, wet processes such as electrodeposition methods, silver salt methods, electroplating methods, electroless plating methods, lamination of metal foil, etc., and are appropriately selected according to the material of the base electrode.

<Solder material layer>
A solder material is used as a bonding material for bonding the electrodes to the chip of the P-type thermoelectric conversion material and the chip of the N-type thermoelectric conversion material.
The solder material is not particularly limited, but as a solder material with a relatively low melting point, from the viewpoint of lead-free and/or cadmium-free, for example, Sn-In system In52Sn48 [melting temperature: solidus temperature (about 119 ° C. ), liquidus temperature (about 119 ° C.)], Sn-Bi system Bi58Sn42 [melting temperature: solidus temperature (about 139 ° C.), liquidus temperature (about 139 ° C.)], Sn-Zn-Bi system Sn89Zn8Bi3 [melting temperature: solidus temperature (about 190 ° C.), liquidus temperature (about 196 ° C.)], Sn-Zn-based Sn91Zn9 [melting temperature: solidus temperature (about 198 ° C.), liquidus temperature (about 198° C.)] and the like.
As a solder material with a relatively high melting point, from the viewpoint of lead-free and/or cadmium-free, for example, Sn-Sb-based Sn95Sb5 [melting temperature: solidus temperature (about 238 ° C.), liquidus temperature ( about 241° C.)], Sn—Cu-based Sn99.3Cu0.7 [melting temperature: solidus temperature (about 227° C.), liquidus temperature (about 228° C.)], Sn—Cu—Ag-based Sn99Cu0.7. 7Ag0.3 [melting temperature: solidus temperature (about 217 ° C.), liquidus temperature (about 226 ° C.)], Sn-Ag-based Sn97Ag3 [melting temperature: solidus temperature (about 221 ° C.), liquid phase linear temperature (about 222° C.)], Sn—Ag—Cu system Sn96.5Ag3Cu0.5 [melting temperature: solidus temperature (about 217° C.), liquidus temperature (about 219° C.)], Sn95.5Ag4Cu0.5. 5 [melting temperature: solidus temperature (about 217 ° C.), liquidus temperature (about 219 ° C.)], Sn-Ag-Cu system Sn95.8Ag3.5Cu0.7 [melting temperature: solidus temperature (about 217° C.), liquidus temperature (about 217° C.)] and the like.
Considering the heat resistance of the substrate, electrodes, etc. that constitute the thermoelectric conversion module, the above solder materials can be used as appropriate.

The thickness of the solder material layer containing the solder material (before solidification at the time of formation) is appropriately adjusted according to the dimensions including the area of the joint (joint region), the thickness of the structural body, and the number of layers. It is 500 μm, preferably 20 to 400 μm, more preferably 40 to 300 μm, still more preferably 60 to 180 μm. When the thickness of the solder material layer is within this range, it becomes easier to suppress leakage of solder to the outside of the joint due to flow of molten solder.
The thickness of the solder material layer containing the solder material (after solidification by heating and cooling) is preferably 10-200 μm, more preferably 20-150 μm, still more preferably 30-130 μm, and particularly preferably 40-120 μm. When the thickness of the solder material layer is within this range, it becomes easier to improve the bondability of the thermoelectric conversion material with the chip and the electrode.

Methods for applying the solder material onto the substrate include known methods such as stencil printing, screen printing, and dispensing. Although the heating temperature varies depending on the solder material, substrate, etc. used, the heating is usually carried out at 100 to 280° C. for 0.5 to 20 minutes.

Commercially available solder materials include the following. For example, 42Sn/58Bi alloy [manufactured by Tamura Corporation, product name: SAM10-401-27, melting temperature: solidus temperature (about 139°C), liquidus temperature (about 139°C)], 96.5Sn3.0Ag0 .5Cu alloy [manufactured by Nihon Handa Co., product name: PF305-153TO, melting temperature: solidus temperature (about 217 ° C.), liquidus temperature (about 219 ° C.)], Sn / 57Bi alloy [manufactured by Nihon Handa Co., product name : PF141-LT7H0, melting temperature: solidus temperature (about 137° C.)] and the like can be used.

<Solder receiving layer>
In joining the thermoelectric conversion material chip to the thermoelectric conversion module electrode, a solder receiving layer may be provided in advance on the thermoelectric conversion material chip.
The solder-receiving layer has the function of improving the bondability of the solder material layer on the electrode side facing the thermoelectric conversion material chip, and is provided on one surface of the thermoelectric conversion material chip and the other surface of the thermoelectric conversion material chip ( It is preferable to laminate directly on the upper and lower surfaces).

The solder-receiving layer includes a metallic material. The metal material is preferably at least one selected from gold, silver, rhodium, platinum, chromium, palladium, tin, nickel, and alloys containing any of these metal materials. Among these, a two-layer structure of gold, silver, nickel, or tin and gold or nickel and gold is more preferable, and silver is more preferable from the viewpoint of material cost, high thermal conductivity, and bonding stability.
Furthermore, the solder-receiving layer may be formed 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 resin components by firing or the like as described later. Silver paste and aluminum paste are preferable as the paste material.

The thickness of the solder-receiving layer is preferably 10 nm to 50 μm, more preferably 50 nm to 16 μm, even more preferably 200 nm to 4 μm, particularly preferably 500 nm to 3 μm. When the thickness of the solder-receiving layer is within this range, the adhesion to the surface of the thermoelectric conversion material chip and the surface of the solder material layer on the electrode side are excellent, and highly reliable bonding can be obtained. In addition, since high thermal conductivity can be maintained as well as electrical conductivity, the thermoelectric performance of the thermoelectric conversion module is maintained without deteriorating.
The solder-receiving layer may be formed by depositing the metal material as it is and used as a single layer, or may be used as a multilayer by laminating two or more metal materials. Alternatively, the film may be formed as a composition containing a metal material in a solvent, resin, or the like. However, in this case, from the viewpoint of maintaining high electrical conductivity and high thermal conductivity (maintaining thermoelectric performance), it is recommended to remove the resin components, including the solvent, etc., by baking, etc., as the final form of the solder-receiving layer. preferable.

The solder-receiving layer is formed using the metal material described above.
As a method for forming the solder-receiving layer, after providing a solder-receiving layer having no pattern formed on the chip of the thermoelectric conversion material, a known physical treatment or chemical treatment mainly based on a photolithography method, or any of these processes is performed. or a method of forming a pattern of the direct bonding material-receiving layer by a screen printing method, a stencil printing method, an inkjet method, or the like.
The method for forming the solder-receiving layer without a pattern includes PVD (physical vapor deposition) such as vacuum deposition, sputtering, and ion plating, or CVD such as thermal CVD and atomic layer deposition (ALD). (Chemical Vapor Deposition) and other vacuum film formation methods, or various coating methods such as dip coating, spin coating, spray coating, gravure coating, die coating, and doctor blade methods, and wet processes such as electrodeposition. , silver salt method, electroplating method, electroless plating method, metal foil lamination, and the like, which are appropriately selected according to the bonding material.
From the viewpoint of maintaining thermoelectric performance, the solder-receiving layer is required to have high electrical conductivity and high thermal conductivity. It is preferred to use a filmed solder-receiving layer.

<Chip of thermoelectric conversion material>
The thermoelectric conversion material chip is not particularly limited, and may be made of a thermoelectric semiconductor material or a thin film made of a thermoelectric semiconductor composition.
Thermoelectric semiconductor material (hereinafter sometimes referred to as "thermoelectric semiconductor particles"), resin, ionic liquid, and inorganic ionic compound. is preferred.

(thermoelectric semiconductor material)
The thermoelectric semiconductor material, that is, the thermoelectric semiconductor material that constitutes the chip of the P-type thermoelectric conversion material and the chip of the N-type thermoelectric conversion material, should be a material that can generate a thermoelectromotive force by applying a temperature difference. bismuth-tellurium thermoelectric semiconductor materials such as P-type bismuth telluride and N-type bismuth telluride; telluride thermoelectric semiconductor materials such as GeTe and PbTe; antimony _- tellurium thermoelectric semiconductor materials; zinc _- antimony thermoelectric semiconductor materials such as Sb _{2 and} Zn ₄ Sb ₃ ; silicon _- germanium thermoelectric semiconductor materials such as SiGe; bismuth selenide thermoelectric semiconductor materials such as Bi ₂ Se ₃ ; Silicide thermoelectric semiconductor materials such as MnSi _1.73 and Mg ₂ Si; oxide thermoelectric semiconductor materials; Heusler materials such as FeVAl, FeVAlSi and FeVTiAl; and sulfide thermoelectric semiconductor materials such as TiS ₂ .
Among these, a bismuth-tellurium-based thermoelectric semiconductor material, a telluride-based thermoelectric semiconductor material, an antimony-tellurium-based thermoelectric semiconductor material, or a bismuth-selenide-based thermoelectric semiconductor material is preferable.

More preferably, it is a bismuth-tellurium-based thermoelectric semiconductor material such as P-type bismuth telluride or N-type bismuth telluride.
The p-type bismuth telluride has holes as carriers and a positive Seebeck coefficient, and is preferably represented by, for example, Bi _X Te ₃ Sb _2-X . In this case, X preferably satisfies 0<X≦0.8, more preferably 0.4≦X≦0.6. When X is greater than 0 and 0.8 or less, the Seebeck coefficient and electrical conductivity are increased, and the properties of the P-type thermoelectric element are maintained, which is preferable.
The N-type bismuth telluride has electrons as carriers and a negative Seebeck coefficient, and is represented by, for example, Bi ₂ Te _3-Y Se _Y , which is preferably used. In this case, Y preferably satisfies 0≦Y≦3 (when Y=0: Bi ₂ Te ₃ ), more preferably 0<Y≦2.7. When Y is 0 or more and 3 or less, the Seebeck coefficient and electrical conductivity are increased, and the properties of the N-type thermoelectric element are maintained, which is preferable.

The content of the thermoelectric semiconductor material or thermoelectric semiconductor particles in the thermoelectric semiconductor composition is preferably 30 to 99% by mass. It is more preferably 50 to 96% by mass, still more preferably 70 to 95% by mass. If the content of the thermoelectric semiconductor material or the thermoelectric semiconductor particles is within the above range, the Seebeck coefficient (absolute value of the Peltier coefficient) is large, and the decrease in electrical conductivity is suppressed, and only the thermal conductivity decreases. It is preferable because a film having sufficient film strength and flexibility can be obtained while exhibiting thermoelectric performance.

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

Further, the thermoelectric semiconductor particles are preferably annealed (hereinafter sometimes referred to as "annealing treatment A"). By performing the annealing treatment A, the crystallinity of the thermoelectric semiconductor particles is improved, and the surface oxide film of the thermoelectric semiconductor particles is removed, so that the Seebeck coefficient or Peltier coefficient of the thermoelectric conversion material increases, and the thermoelectric figure of merit 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, under an inert gas atmosphere such as nitrogen and argon. , It is preferably carried out under a reducing gas atmosphere such as hydrogen or under vacuum conditions, more preferably under a mixed gas atmosphere of an inert gas and a reducing gas. Although the specific temperature conditions depend on the thermoelectric semiconductor particles used, it is generally preferred that the temperature be below the melting point of the particles and be 100 to 1500° C. for several minutes to several tens of hours.

(resin)
Resin has the effect of physically bonding between thermoelectric semiconductor materials (thermoelectric semiconductor particles), can increase the flexibility of the thermoelectric conversion module, and facilitates the formation of a thin film by coating or the like.
Examples of resins include heat-resistant resins and binder resins.

(Heat resistant resin)
The heat-resistant resin maintains various physical properties such as mechanical strength and thermal conductivity as a resin when crystal growth of thermoelectric semiconductor particles is performed by annealing a thin film made of a thermoelectric semiconductor composition.
The heat-resistant resin is preferably a polyamide resin, a polyamide-imide resin, a polyimide resin, or an epoxy resin because it has higher heat resistance and does not adversely affect the crystal growth of the thermoelectric semiconductor particles in the thin film, and has excellent flexibility. Polyamide resins, polyamideimide resins, and polyimide resins are more preferable. When a polyimide film is used as the first substrate or the second substrate, which will be described later, polyimide resin and polyamideimide resin are more preferable as the heat-resistant resin from the viewpoint of adhesion to the polyimide film. In the present invention, polyimide resin is a general term for polyimide and its precursors.

The heat-resistant resin preferably has a decomposition temperature of 300° C. or higher. If the decomposition temperature is within the above range, 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.

In addition, the heat-resistant resin preferably has a mass reduction rate at 300° C. of 10% or less, more preferably 5% or less, and even more preferably 1% or less by thermogravimetry (TG). . If the mass reduction rate is within the above range, even when the thin film made of the thermoelectric semiconductor composition is annealed, the bendability of the tip of the thermoelectric conversion material can be maintained without losing the function as a binder, as described later. 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, further preferably 2 to 15% by mass. % by mass. When the content of the heat-resistant resin is within the above range, it functions as a binder for the thermoelectric semiconductor material, making it easier to form a thin film, and a film having both high thermoelectric performance and film strength can be obtained, resulting in thermoelectric conversion. A resin portion is present on the outer surface of the chip of material.

The binder resin can be easily peeled off from substrates such as glass, alumina, silicon, etc. used when making chips of thermoelectric conversion materials after baking (annealing) treatment (corresponding to "annealing treatment B" described later, the same applies hereinafter). to

The binder resin refers to a resin in which 90% by mass or more decomposes at a baking (annealing) temperature or higher, more preferably a resin in which 95% by mass or more decomposes, and a resin in which 99% by mass or more decomposes. is particularly preferred. In addition, a resin that maintains various physical properties such as mechanical strength and thermal conductivity without impairing when crystal growth of thermoelectric semiconductor particles is performed by baking (annealing) a coating film (thin film) made of a thermoelectric semiconductor composition. more preferred.
As the binder resin, if a resin that decomposes 90% by mass or more at a firing (annealing) temperature or higher, that is, a resin that decomposes at a lower temperature than the heat-resistant resin described above, the binder resin is decomposed by firing, resulting in a fired body. The content of the binder resin, which is an insulating component contained therein, is reduced, and the crystal growth of the thermoelectric semiconductor particles in the thermoelectric semiconductor composition is promoted. can be improved.
Whether or not a resin decomposes at a predetermined value (for example, 90% by mass) at a firing (annealing) temperature or higher is determined by thermogravimetric measurement (TG) at the mass reduction rate at the firing (annealing) temperature (before decomposition The value obtained by dividing the mass after decomposition by the mass).

A thermoplastic resin or a curable resin can be used as such a binder resin. Examples of thermoplastic resins include polyolefin resins such as polyethylene, polypropylene, polyisobutylene, and polymethylpentene; polycarbonates; thermoplastic polyester resins such as polyethylene terephthalate and polyethylene naphthalate; polystyrene, acrylonitrile-styrene copolymers, and polyacetic acid. Polyvinyl polymers such as vinyl, ethylene-vinyl acetate copolymer, vinyl chloride, polyvinylpyridine, polyvinyl alcohol and polyvinylpyrrolidone; polyurethanes; cellulose derivatives such as ethyl cellulose; Examples of curable resins include thermosetting resins and photocurable resins. Examples of thermosetting resins include epoxy resins and phenol resins. Examples of photocurable resins include photocurable acrylic resins, photocurable urethane resins, and photocurable epoxy resins. These may be used individually by 1 type, and may use 2 or more types together.
Among these, from the viewpoint of the electrical resistivity of the thermoelectric conversion material in the thermoelectric conversion material layer, thermoplastic resins are preferred, cellulose derivatives such as polycarbonate and ethyl cellulose are more preferred, and polycarbonate is particularly preferred.

The binder resin is appropriately selected according to the temperature of the baking (annealing) treatment for the thermoelectric semiconductor material in the baking (annealing) treatment step. From the viewpoint of the electrical resistivity of the thermoelectric conversion material in the thermoelectric conversion material layer, it is preferable to perform the baking (annealing) treatment at a temperature higher than the final decomposition temperature of the binder resin.
As used herein, the term “final decomposition temperature” refers to the temperature at which the mass reduction rate at the firing (annealing) temperature by thermogravimetry (TG) is 100% (the mass after decomposition is 0% of the mass before decomposition). Say.

The final decomposition temperature of the binder resin is generally 150-600°C, preferably 200-560°C, more preferably 220-460°C, and particularly preferably 240-360°C. If a binder resin having a final decomposition temperature within this range is used, it functions as a binder for the thermoelectric semiconductor material and facilitates the formation of a thin film during printing.

The content of the binder resin in the thermoelectric semiconductor composition is 0.1 to 40% by mass, preferably 0.5 to 20% by mass, more preferably 0.5 to 10% by mass, and particularly preferably 0.5 to 5% by mass. % by mass. When the content of the binder resin is within the above range, the electric resistivity of the thermoelectric conversion material in the thermoelectric conversion material layer can be reduced.

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

(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 from -50°C to less than 400°C. In other words, an 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, more preferably 0° C. or higher and 150° C. or lower. Ionic liquids have characteristics such as extremely low vapor pressure and non-volatility, excellent thermal and electrochemical stability, low viscosity, and high ionic conductivity. Therefore, it can effectively suppress the decrease in electrical conductivity between thermoelectric semiconductor materials as a conductive auxiliary agent. In addition, the ionic liquid exhibits high polarity based on an aprotic ionic structure and is excellent in compatibility with heat-resistant resins, so that the electrical conductivity of the thermoelectric conversion material can be made uniform.

Known or commercially available ionic liquids 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; Phosphine-based cations and derivatives thereof; cation components such as lithium cations and derivatives thereof, 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 ) ₂ N ⁻ , C ₃ F ₇ COO ⁻ , (CF ₃ SO ₂ )(CF ₃ CO)N ⁻ and other anion components.

Among the above ionic liquids, the cation component of the ionic liquid is pyridinium cation and its derivatives from the viewpoint of high-temperature stability, compatibility with thermoelectric semiconductor materials and resins, suppression of reduction in electrical conductivity in the gaps of thermoelectric semiconductor materials, etc. , imidazolium cations and derivatives thereof.

1-butyl-4-methylpyridinium bromide, 1-butylpyridinium bromide, and 1-butyl-4-methylpyridinium hexafluorophosphate are preferred as the ionic liquid containing a pyridinium cation and its derivative as a cationic component.

In addition, ionic liquids containing imidazolium cations and derivatives thereof as cationic components include [1-butyl-3-(2-hydroxyethyl) imidazolium bromide], [1-butyl-3-(2-hydroxyethyl) imidazo Lithium tetrafluoroborate] is preferred.

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

The content 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, still more preferably 1.0 to 20% by mass. If the content 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 that can be included in the thermoelectric semiconductor composition is a compound composed of at least cations and anions. Inorganic ionic compounds exist in a solid state over a wide temperature range of 400 to 900°C and have characteristics such as high ionic conductivity. can be suppressed.

The content 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, still more preferably 1.0 to 10% by mass. If the content 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 with improved thermoelectric performance can be obtained.
When the inorganic ionic compound and the ionic liquid are used together, 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, more preferably is 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 is not particularly limited, and for example, the thermoelectric semiconductor particles, the ionic liquid, the inorganic The thermoelectric semiconductor composition may be prepared by adding an ionic compound (when used in combination with an ionic liquid), the heat-resistant resin, and optionally the other additives and a solvent, followed by mixing and dispersing.
Examples of the solvent include solvents such as toluene, ethyl acetate, methyl ethyl ketone, alcohol, tetrahydrofuran, methylpyrrolidone, and ethyl cellosolve. These solvents may be used singly or in combination of two or more. 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 thermoelectric conversion material chip made of the thermoelectric semiconductor composition is not particularly limited. 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 thermoelectric conversion material chips can be obtained easily and at low cost.
Examples of the method for applying the thermoelectric semiconductor composition to obtain a thermoelectric conversion material chip include 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, A known method such as a doctor blade method can be used, and there is no particular limitation. When a coating film is formed in a pattern, a screen printing method, a slot die coating method, or the like, which enables simple pattern formation using a screen plate having a desired pattern, is preferably used.
Next, by drying the obtained coating film, a chip of the thermoelectric conversion material is formed. As the drying method, a conventionally known drying method such as hot air drying method, hot roll drying method, infrared irradiation method, etc. is 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.
Moreover, when a solvent is used in the preparation of the thermoelectric semiconductor composition, the heating temperature is not particularly limited as long as it is within a temperature range where the solvent used 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, still more preferably 5 to 400 μm from the viewpoint of thermoelectric performance and film strength.

The thermoelectric conversion material chip as a thin film made of the thermoelectric semiconductor composition is preferably further subjected to an annealing treatment (hereinafter sometimes referred to as "annealing treatment B"). By performing the annealing treatment B, the thermoelectric performance can be stabilized, and the thermoelectric semiconductor particles in the thin film can be crystal-grown, thereby further improving the thermoelectric performance. Annealing treatment B is not particularly limited, but is usually performed in an atmosphere of an inert gas such as nitrogen or argon with a controlled gas flow rate, in a reducing gas atmosphere, or under vacuum conditions, depending on the resin and ionic compound used. Depending on the heat resistance temperature, etc., it is carried out at 100 to 500° C. for several minutes to several tens of hours.

As the sacrificial layer, a resin such as polymethyl methacrylate or polystyrene, or a releasing agent such as a fluorine-based releasing agent or a silicone-based releasing agent can be used. When the sacrificial layer is used, the chips of the thermoelectric conversion material formed on the base material such as glass can be easily separated from the glass or the like after the annealing treatment B.
Formation of the sacrificial layer is not particularly limited, and can be performed by known methods such as flexographic printing and spin coating.

<Substrate>
The substrate on which the electrodes are formed is not particularly limited, and known substrates such as glass substrates, silicon substrates, ceramic substrates, and resin substrates can be used.
From the viewpoint of flexibility and thinness, it is preferable to use a plastic film (resin substrate). 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 the heat resistance and dimensional stability are high. From this point of view, the plastic film is preferably a polyimide film, a polyamide film, a polyetherimide film, a polyaramid film, or a polyamideimide film, and more preferably a polyimide film from the viewpoint of high versatility.

The thickness of the plastic film is preferably 1 to 1000 μm, more preferably 10 to 500 μm, even more preferably 20 to 100 μm, from the viewpoint of flexibility, heat resistance and dimensional stability.
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 heat dimensional change rate measured at 200° C. in accordance with JIS K7133 (1999) is preferably 0.5% or less, more preferably 0.3% or less. The linear expansion coefficient in the plane direction measured in accordance with JIS K7197 (2012) is 0.1 ppm · ° C ^-1 to 50 ppm · ° C ^-1 and 0.1 ppm · ° C ^-1 to 30 ppm · ° C ^-1 is more preferred.

[Thermoelectric conversion module]
The electrode for thermoelectric conversion module of the present invention is preferably applied to a thermoelectric conversion module having a configuration of a π-type thermoelectric conversion element.

FIG. 3 is a cross-sectional view for explaining an example of the configuration of a thermoelectric conversion module including the thermoelectric module electrode of the present invention. The thermoelectric conversion module 11 is composed of so-called π-type thermoelectric conversion elements, An electrode 13 having a first substrate 12a and a second substrate 12b, a base electrode 13a formed on the first substrate 12a and a structure portion 13c, a chip 14p of a P-type thermoelectric conversion material, and an N-type an electrode 13 comprising a solder material layer 15' between the lower surface of each of the chips 14n of thermoelectric conversion material and further comprising a structure portion 13c on a base electrode 13b formed on the second substrate 12b; A solder material layer 15' is included between the upper surface of each of the tip 14p of thermoelectric conversion material of type N and the tip 14n of thermoelectric conversion material of N type.
In the thermoelectric conversion module, the electrode for thermoelectric module of the present invention can be used as the electrode 13 . Further, the substrates described above can be used as the first substrate 2a and the second substrate 2b. Furthermore, a solder material layer containing the solder material described above can be used as the solder material layer 15'.

The electrode for a thermoelectric conversion module of the present invention can suppress leakage of molten solder to the outside of the joints between chips of adjacent thermoelectric conversion materials and prevent short circuits between chips. The yield of the manufacturing process can be improved. Furthermore, it can be expected to lead to higher density mounting of thermoelectric conversion modules.

Next, the present invention will be described in more detail by way of examples, but the present invention is not limited by these examples.

Short circuits between the chips of the P-type thermoelectric conversion material and the chips of the N-type thermoelectric conversion material in the thermoelectric conversion modules including the electrodes for thermoelectric conversion modules produced in Examples and Comparative Examples were evaluated by the following method.

・Evaluation of short circuit between chips of thermoelectric conversion module An X-ray transmission inspection device (manufactured by Nordson, model name " DAGE XD7500VR") and evaluated according to the following criteria.
A: In the transmission image, the side surface of the chip of the P-type thermoelectric conversion material and the side surface of the chip of the N-type thermoelectric conversion material are not in direct physical contact via the solder material.
B: In the transmission image, the side surface of the chip of the P-type thermoelectric conversion material and the side surface of the chip of the N-type thermoelectric conversion material are in direct physical contact via the solder material.

(Example 1)
(1) Production of thermoelectric semiconductor composition (production of thermoelectric semiconductor particles)
P-type bismuth telluride Bi _0.4 Te ₃ Sb _1.6 (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: 90 μm), which is a bismuth-tellurium thermoelectric semiconductor material, was milled in a planetary ball mill (Premium line P -7) was used and pulverized in an air atmosphere to produce thermoelectric semiconductor particles T1 having an average particle size of 2.5 μm.
In addition, N-type bismuth telluride Bi ₂ Te ₃ (manufactured by Kojundo Chemical Laboratory Co., Ltd., particle size: 90 μm), which is a bismuth-tellurium thermoelectric semiconductor material, was treated in the same manner as described above to form thermoelectric semiconductor particles having an average particle size of 2.5 μm. T2 was produced.
The particle size distribution of the pulverized thermoelectric semiconductor particles T1 and T2 was measured using a laser diffraction particle size analyzer (Mastersizer 3000 manufactured by Malvern).
(Preparation of coating liquid of thermoelectric semiconductor composition)
Coating liquid (P)
83.3 parts by mass of the P-type bismuth telluride Bi _0.4 Te _3.0 Sb _1.6 particles T1 obtained above, polyamideimide (manufactured by Arakawa Chemical Industries, product name: Compoceran AI301, A coating liquid (P ) was prepared.
Coating liquid (N)
91.6 parts by mass of the N-type bismuth telluride Bi ₂ Te ₃ particles T2 obtained above, polyamideimide (manufactured by Arakawa Chemical Industries, product name: Compoceran AI301, solvent: N-methylpyrrolidone, solid concentration: 18% by mass) and 4.8 parts by mass of 1-butylpyridinium bromide as an ionic liquid were mixed and dispersed to prepare a coating liquid (N) comprising a thermoelectric semiconductor composition.

(2) Preparation of chip of thermoelectric conversion material As a sacrificial layer on a glass substrate (soda lime glass) with a thickness of 0.7 mm, polymethyl methacrylate resin (PMMA) (manufactured by Sigma-Aldrich, trade name: polymethacrylic acid A polymethyl methacrylate resin solution having a solid content concentration of 10% by mass in which methyl (methyl) was dissolved in toluene was spin-coated to form a film having a thickness of 10.0 μm after drying.
Next, the coating liquid (P) prepared in (1) above is applied onto the sacrificial layer through a metal mask by screen printing, and dried at a temperature of 120° C. in an air atmosphere for 7 minutes (thickness : 350 μm). Thereafter, a pressure was applied at 250° C. and 110 MPa for 10 minutes in an air atmosphere to form a thin film of a thermoelectric semiconductor composition containing particles of a P-type thermoelectric semiconductor material with a thickness of 200 μm. The resulting thin film was heated at a heating rate of 5 K/min in a mixed gas atmosphere 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 allow the grains of thermoelectric semiconductor material to crystallize and form a 200 μm thick film containing P-type bismuth telluride Bi _0.4 Te ₃ Sb _1.6 with top and bottom surfaces of 1.15 mm×1.15 mm each and a thickness of 200 μm. A rectangular parallelepiped P-type thermoelectric conversion material chip was obtained.
In addition, the coating liquid (N) prepared in (1) above was changed, and the pressurization conditions were held at 250 ° C. and 37 MPa for 10 minutes in an air atmosphere, and at 360 ° C. in a mixed gas atmosphere of hydrogen and argon for 1 hour. , the same method except that the thin film was annealed, containing N-type bismuth telluride Bi ₂ Te ₃ , the upper and lower surfaces were 1.15 mm × 1.15 mm and the thickness was 200 μm (thickness before pressing: 390 μm). A chip of a rectangular parallelepiped N-type thermoelectric conversion material was obtained.

(3) Formation of solder-receiving layer P-type and N-type thermoelectric conversion material chips after annealing treatment are peeled off from the glass substrate, and all surfaces of the P-type and N-type thermoelectric conversion material chips are coated by electroless plating. As a solder receiving layer, a nickel layer (thickness: 3 μm) and a gold layer (thickness: 40 nm) were laminated in this order.
Then, the solder-receiving layers on the sides of the chips of the P-type and N-type thermoelectric conversion materials are mechanically polished, i.e. , sandpaper (number 2000) to obtain chips of P-type and N-type thermoelectric conversion materials having solder-receiving layers only on the upper and lower surfaces. In addition, in order to completely remove the solder-receiving layer laminated on the side surface, the chip including a part of the side wall of the P-type and N-type thermoelectric conversion material was polished.

(4) Formation of electrodes First, a copper-clad laminate (manufactured by Ube Exsimo Co., Ltd., product name: BR1305, polyimide substrate, thickness: 12.5 μm, copper foil, thickness: 12 μm) in which copper foil is attached to a polyimide substrate was prepared. A resist was patterned on the surface of the copper foil so that four rectangular parallelepiped structural parts of 0.15×0.15 mm and 20 μm in thickness could be formed per joint. After patterning, the copper foil on the bottom surface of the recesses of the resist is plated with copper by an electrolytic method, and the resist residue is removed, resulting in a rectangular parallelepiped structure made of copper (material) having the above dimensions on the copper foil. formed a department.
Next, by an etching method, the outer diameter is 1.90 mm × 0.90 mm [electrode joint 1 (for joining with the chip of the P-type thermoelectric conversion material): 0.90 mm × 0.90 mm, electrode joint 2 (N type thermoelectric conversion material chip): 0.90 mm × 0.90 mm, distance between adjacent joints 1 and 2: 0.10 mm], a total of 20 sets, 2 rows × 10 columns, electrodes A substrate having an electrode with a rectangular parallelepiped structural body by forming a pattern and then laminating a nickel layer (thickness: 3 μm) and a gold layer (thickness: 40 nm) in this order by electroless plating (hereinafter sometimes referred to as "electrode substrate").
In addition, the four structure parts were evenly arranged with respect to the center of the joint part as in FIG.

<Production of thermoelectric conversion module>
Solder material (manufactured by Koki Co., Ltd., product name: S3X70-M500) is applied by stencil printing using a metal plate with an opening of 0.5 × 0.5 mm and a thickness of 100 μm at the center of the electrode joint of the electrode substrate. P-type and N-type thermoelectric conversion material chips (0 .9×0.9 mm) were placed so that the center of each chip coincided with the center of the solder material layer and there was no deviation in the in-plane direction.
After that, heat treatment by reflow is performed at 235° C. for 1 minute, the temperature is returned to room temperature, and the solder material layer is cooled and solidified (solder material layer thickness: 23 μm) to join the chips of P-type and N-type thermoelectric conversion materials. did.
Similarly, a metal plate with an opening of 0.5 × 0.5 mm and a thickness of 100 µm was applied to the center of the joint of the electrode provided with the structure part of the opposing electrode substrate (manufactured by Koki Co., Ltd., product name : S3X70-M500) is formed as a solder material layer (thickness before solidification: 100 μm) by stencil printing, and after bonding to the chip, a load of 0.5 N is applied to the chip, 235 ° C. for 1 minute. , heat treatment by reflow, returning to room temperature, and cooling and solidifying the solder material layer (thickness after solidification: 21 μm) to fabricate a thermoelectric conversion module.

In accordance with the short-circuit evaluation between chips of the thermoelectric conversion module described above, the presence or absence of short-circuiting between the chips of the P-type thermoelectric conversion material and the chips of the N-type thermoelectric conversion material was evaluated. Table 1 shows the results.

(Comparative example 1)
In Example 1, a thermoelectric conversion module electrode was produced in the same manner as in Example 1 except that the region of the electrode junction did not have a structural body portion, and a thermoelectric conversion module was produced using the electrode. In the same manner as in Example 1, the occurrence of short circuits between the chips of the P-type thermoelectric conversion material and the chips of the N-type thermoelectric conversion material was evaluated. Table 1 shows the results.

It can be seen that in Example 1 in which the electrode has the structure portion, there is no short circuit due to leakage of molten solder between the thermoelectric conversion material chips, unlike Comparative Example 1 in which the electrode does not have the structure portion.

ADVANTAGE OF THE INVENTION The electrode for thermoelectric conversion modules of this invention can suppress the leakage of molten solder between the chips of the thermoelectric conversion material adjacent to each other, and can prevent the short circuit between the chips.
Therefore, when the electrode for a thermoelectric conversion module of the present invention is applied to a thermoelectric conversion module composed of π-type thermoelectric conversion elements, it is useful for improving the deterioration of the thermoelectric performance and improving the yield of the manufacturing process. Since it can lead to high-density mounting of the module, it is preferably used for known modules for power generation and cooling.

3: Electrodes 3a, 3b: Base electrode 3c: Structure portion 4p: Chip of P-type thermoelectric conversion material 4n: Chip of N-type thermoelectric conversion material 5: Solder material layer (before solidification)
5': Solder material layer (after solidification)
6p: Joint portion (joint region) between the electrode and the chip of the P-type thermoelectric conversion material
6n: Joint portion (joint region) of the electrode and the tip of the N-type thermoelectric conversion material
11: Thermoelectric conversion module 12a: First substrate 12b: Second substrate 13: Electrodes 13a, 13b: Base electrode 13c: Structural part 14p: P-type thermoelectric conversion material chip 14n: N-type thermoelectric conversion material chip 15 ': Solder material layer (after solidification)

Claims (5)

An electrode for a thermoelectric conversion module in which a chip of a P-type thermoelectric conversion material and a chip of an N-type thermoelectric conversion material that are separated from each other are joined to electrodes via a solder material,
An electrode for a thermoelectric conversion module, wherein the electrode includes a structure portion in a region where the electrode is joined to the chip of the P-type thermoelectric conversion material and the chip of the N-type thermoelectric conversion material. 2. The electrode for thermoelectric conversion module according to claim 1, wherein the shape of said structure portion is selected from rectangular parallelepiped, cubic, columnar, prismatic, pyramidal, conical, truncated pyramidal, and truncated conical. 3. The electrode for thermoelectric conversion module according to claim 1, wherein the material of said structure part is selected from gold, silver, copper, nickel and aluminum. The electrode for thermoelectric conversion module according to any one of claims 1 to 3, wherein said structure portion is provided with a space in said region. A thermoelectric conversion module, wherein the electrode for thermoelectric conversion module according to any one of claims 1 to 4 is used for a π-type thermoelectric conversion element.

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