JPH0936437A - Production of thermoelectric conversion module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a method for producing a thermoelectric conversion module employing a high strength thermoelectric conversion element excellent in thermoelectric conversion performance. SOLUTION: In the method for producing a thermoelectric conversion module comprising a thermoelectric conversion element obtained by firing a thermoelectric conversion material containing more than one kind of element selected from a group of Bi, Te, Se and Sb and electrodes, metal particles having mean particle size in the range of 10-200μm are bonded to the surface of electrode by fusing a part of metal particle to the electrode through heat treatment at a temperature lower than the melting point of metal particle. More specifically, powder of thermoelectric conversion material having mean particle size smaller than that of metal particle is formed on the electrode having enhanced surface roughness and then it is fired.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelectric conversion module manufacturing method utilizing the Peltier effect.

[0002]

2. Description of the Related Art A thermoelectric conversion module utilizing the Peltier effect is a Peltier device in which P-type semiconductor elements and N-type semiconductor elements which are thermoelectric conversion elements are alternately arranged between two insulating layers and electrically connected in series. By applying a DC voltage to the element group, heat or heat is generated on the surface of the insulating layer, and it is widely used in various fields in thermoelectric power generation and thermoelectric cooling.

As a method of manufacturing this thermoelectric conversion element, generally, as disclosed in JP-A-1-202343, a rod-shaped ingot which is close to a single crystal is grown by melting a raw material powder and then by a zone melting method. A single crystal method, a HIP method that requires a high pressure when firing a raw material powder, or a hot pressing method (HP method) that produces an ingot by hot pressing, as disclosed in JP-A-1-106478. Then, a bulk thermoelectric conversion material ingot is produced, cut into small thermoelectric conversion elements according to the application, and a P-type semiconductor element and an N-type semiconductor element are alternately arranged in series on the insulating substrate using solder. To produce a thermoelectric conversion module.

Therefore, in the manufacturing method as described above,
In order to obtain a thermoelectric conversion element, an expensive firing device is required, and in the thermoelectric conversion element cutting step depending on the application, there is a lot of material loss due to a cutting margin, and it is necessary to produce about 1 mm square thermoelectric conversion element. % Or more material loss has occurred. In addition, since the material is brittle, problems such as cracking and chipping occur during cutting, and the yield of thermoelectric conversion elements is poor. Moreover, with the recent miniaturization of thermoelectric conversion modules, thermoelectric conversion elements tend to be thinned and downsized, and in a method of manufacturing a thermoelectric conversion element that involves a cutting step, problems such as cracking and chipping are solved. We have not reached the stage where we can fully respond. Furthermore, many work processes that cannot be automated or labor-saving were required. Further, it is very difficult to achieve the densification when the above-mentioned firing operation is not carried out, so that the strength of the thermoelectric conversion element becomes very low, and the reliability is impaired.

The above is a major factor in increasing the manufacturing cost of the thermoelectric conversion module and making it very difficult to obtain a high-strength thermoelectric conversion module. Further, a method of adding quartz glass or the like and firing is disclosed in JP-A-3
Although disclosed in JP-A-9-10374, sufficient characteristics have not been obtained. Attempts have been made to reduce the manufacturing cost of thermoelectric conversion modules by firing at atmospheric pressure, but sufficient results have not yet been obtained. Therefore, it has been desired to develop a method for manufacturing a thermoelectric conversion module that can obtain a thermoelectric conversion module having high strength and excellent thermoelectric conversion performance without a special firing operation.

[0006]

SUMMARY OF THE INVENTION The present invention has been made in view of the above facts, and an object of the present invention is to provide a thermoelectric conversion module having a high strength and a thermoelectric conversion element excellent in thermoelectric conversion performance. It is to provide a manufacturing method.

[0007]

The method of manufacturing a thermoelectric conversion module according to claim 1 of the present invention is a thermoelectric conversion containing at least two elements selected from the group consisting of Bi, Te, Se and Sb elements. In a method for producing a thermoelectric conversion module including a thermoelectric conversion element and an electrode, which are obtained by firing a material, metal particles having an average particle size of 10 to 200 μm are heat-treated at a temperature lower than the melting point of the metal particles on the surface of the electrode, By fusing and bonding a part of the metal particles and the electrode, on the electrode having an increased surface roughness, using a powder of the thermoelectric conversion material having an average particle size smaller than the average particle size of the metal particles. It is characterized by being molded and fired.

In the method of manufacturing a thermoelectric conversion module according to claim 2 of the present invention, the average particle size of the metal particles is 20 to 15.
0 μm.

The method for manufacturing a thermoelectric conversion module according to a third aspect of the present invention is characterized in that the powder of the thermoelectric conversion material has an average particle size of 5 to 100 μm.

A method of manufacturing a thermoelectric conversion module according to a fourth aspect of the present invention is characterized in that the metal particles are at least one selected from the group consisting of Cu, Ni and Al elements.

The method for manufacturing a thermoelectric conversion module according to a fifth aspect of the present invention is characterized in that the atmosphere for bonding the metal particles to the electrode surface is a reduced pressure atmosphere, an inert atmosphere or a reducing atmosphere containing hydrogen. .

The method for manufacturing a thermoelectric conversion module according to claim 6 of the present invention is characterized in that the method for bonding the metal particles to the electrode surface is thermal spraying of the metal particles.

In a method for manufacturing a thermoelectric conversion module according to a seventh aspect of the present invention, before forming the electrode using the powder of the thermoelectric conversion material, Ni, Ni, It is characterized by coating at least one kind selected from the group consisting of Al, W and Mo elements.

[0014]

DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described below in detail.

In the thermoelectric conversion element constituting the thermoelectric conversion module according to the present invention, P-type semiconductor elements and N-type semiconductor elements are alternately arranged between two insulating layers and electrically connected in series by electrodes such as copper electrodes. A P-type semiconductor element or N-type used in a thermoelectric conversion module in which one insulating layer is heated by the so-called Peltier effect and the other insulating layer is absorbed by applying a DC voltage to the Peltier element group connected to the It is a semiconductor device.

The constituent elements of the thermoelectric conversion element according to the present invention are at least bismuth (Bi) and tellurium (T).
e), selenium (Se) or antimony (Sb) element, two or more kinds of elements are required. A small amount of a dopant is added to a raw material containing these constituent elements so as to be a thermoelectric conversion element of an N-type semiconductor or a P-type semiconductor, sufficiently mixed and / or melted if necessary, and then pulverized for thermoelectric conversion. Obtain a powder of material. As the thermoelectric conversion material, for example, B
i-Te alloy, Bi-Sb alloy, Bi-Te-Sb alloy, Bi-Te-Se alloy or Bi-Te-Sb-Se
An alloy or the like can be used, but the combination is not limited to the above.

In the thermoelectric conversion module according to the present invention, it is necessary to increase the surface roughness by bonding metal particles having an average particle size of 10 to 200 μm to the surface of the electrode. That is, when the average particle size of the metal particles is less than 10 μm, the anchor effect cannot be exhibited with the powder of the thermoelectric conversion material, and when it exceeds 200 μm, the formability of the thermoelectric conversion element is deteriorated. . It is necessary to form and fire on the electrode having the increased surface roughness, using the powder of the thermoelectric conversion material having an average particle size smaller than the average particle size of the metal particles.

The average particle size of the metal particles is 20 to 150.
More preferably, the average particle diameter of the powder of the thermoelectric conversion material is 5 to 100 μm. Here, fine powder of 100 μm or less may be blended with powder of the thermoelectric conversion material having a particle size of 100 μm or more. The metal particles are copper (Cu), nickel (Ni)
And at least one selected from the group consisting of aluminum (Al) element, and among them, Cu has high electrical conductivity, high thermal conductivity, low price,
Most suitable in terms of ease of handling. As the electrode, for example, using a Cu plate, the following two methods,
Roughen the surface.

(1) Fusion method Cu powder is sprinkled on the surface of the Cu electrode so as not to form lumps. The method is not particularly specified as long as it can be applied uniformly. For example, Cu particles dispersed in a solvent,
It may be applied to the surface of the Cu plate with a brush. Further, Cu particles may be uniformly dispersed in a Cu plate shape by using a mesh-like material. If the coating amount is too small, the anchor effect with the thermoelectric conversion element is small, and if it is too large, a space is generated between the electrode and the thermoelectric conversion element, which is not preferable. Here, it is preferable that the Cu particles cover the Cu plate in a nearly monodispersed state. That is, the thickness of the Cu particles is preferably about 20 to 150 μm. In the method of bonding the metal particles to the electrode surface, it is preferable that after the metal particles are arranged on the Cu electrode, heat treatment is performed at a temperature lower than the melting point of Cu to fuse a part of the metal particles and the electrode. The atmosphere for bonding the metal particles to the electrode surface is preferably a reduced pressure atmosphere, an inert atmosphere or a reducing atmosphere containing hydrogen. For example, under reduced pressure of 4 to 10 torr, 1
Heat treatment is performed at 000 ° C. for 20 minutes to obtain a Cu electrode in which Cu particles are fused on the surface of the Cu plate. Ni instead of Cu particles
Particles, Al particles and the like can also be used.

(2) Thermal Spraying Method The method of joining the metal particles to the electrode surface is preferably thermal spraying of metal particles. For example, average particle size 50μ
m Cu powder, if necessary, washed and thermally sprayed on a sufficiently dried Cu plate surface, then under a reducing atmosphere or under reduced pressure,
Heat treatment is performed at 500 to 900 ° C.

Before molding the powder of the thermoelectric conversion material onto the electrode, N is formed on the surface of the electrode having the increased surface roughness.
It is preferable to coat at least one selected from the group consisting of i, Al, W and Mo elements. That is,
For example, the surface of the Cu electrode that is joined to the thermoelectric conversion element may be aluminum (A
l), nickel (Ni), tungsten (W), molybdenum (Mo) and other elements are coated. Al, N
The i, W, and Mo elements react with Cu and the thermoelectric conversion element elements to generate further good bonding strength.

(Molding method) The powder of the thermoelectric conversion material is
The surface-roughened electrode thus obtained is molded into a required shape. The method of temporary molding into the required shape is not particularly limited. For example, a molding method such as uniaxial press molding using a mold can be used. Alternatively, the powder of the thermoelectric conversion material may be made into a paste using an acrylic binder, a solvent or the like, and then a desired shape may be applied and printed by a usual screen printing method or the like. Alternatively, the paste thermoelectric conversion material may be formed into a sheet by the doctor blade method and then processed into a required shape. Furthermore, a normal extruding method for a hide-like thermoelectric conversion material,
It is also possible to mold by an injection molding method.

The molded body produced by the above-mentioned method is subjected to main firing after the binder is heated and removed if necessary.
As the main firing atmosphere, if N ₂ , Ar, N ₂ + Ar, or a mixed gas of these inert gas and H ₂ gas is used, oxidation of the material can be suppressed, and further, a reducing action can be obtained. More preferable. That is, the impurity oxygen chemically adsorbed on the surface of the powder of the thermoelectric conversion material is reduced by hydrogen to prevent diffusion, so that the thermoelectric characteristics of the thermoelectric conversion element are improved. The main firing temperature is preferably 410 to 590 ° C.

As described above, according to the method of manufacturing a thermoelectric conversion module of the present invention, a thermoelectric conversion module having high strength and high reliability can be obtained.

[0025]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples.

(Powder Preparation) A small amount of a dopant such as SbI ₃ was added to prepare an ingot of a thermoelectric conversion material having a composition of N-type —Bi ₂ Te _2.85 Se _0.15 . This ingot was crushed using a ball mill to obtain a thermoelectric conversion material powder. The average particle size of the obtained powder was about 15 μm.

Example 1 Cu particles having a purity of 99.9% by weight and an average particle size of about 35 μm (250 mesh under) were dispersed in an acetone solvent. While stirring the Cu particles so as not to settle, oxygen-free C having a purity of 99.9% by weight
A u plate was sprayed and dried to prepare a Cu plate in which Cu particles were dispersed on the surface. This Cu plate was heated at a temperature lower than the melting point of Cu (1083 ° C.) under a reduced pressure of 4 to 10 torr.
By heat-treating at 80 ° C. for 20 minutes, a surface-roughened Cu electrode was obtained. As a result of observing the surface by SEM, the thickness of the layer of Cu particles is about 40 μm, and C
It was confirmed that Cu particles were dispersed in the mono-dispersed layer on the surface of the u electrode and that they were well bonded. On the surface-roughened Cu electrode, a powder of the thermoelectric conversion material having an average particle diameter of about 15 μm was formed into a size of φ10 mm × 10 mm by a uniaxial pressing method, and then 2 ton was obtained using a hydrostatic pressing.
/ Cm ² was pressure-molded to obtain a molded body. Further, the molded body and the electrode were fired in an Ar atmosphere at 450 ° C. for 5 hours to obtain an electrode-bonded thermoelectric conversion module.
The adhesion strength between the thermoelectric conversion element and the electrode after firing is JIS
It measured according to the adhesion test method of H8504, and the result was shown in Table 1.

Example 2 In Example 1, the metal powder used was replaced by Cu particles, and Ni particles having a purity of 99.9% by weight and an average particle size of about 40 μm (200 mesh under) (the melting point of Ni was 1455). The same procedure as in Example 1 was carried out to obtain a thermoelectric conversion module, and the adhesion strength after firing was measured. The results are shown in Table 1.

(Example 3) The metal powder used in Example 1 was replaced with Cu particles, and Al particles having a purity of 99.9% by weight and an average particle size of about 40 μm (200 mesh under) were used. Firing was performed in the same manner as in Example 1 except that the temperature was 630 ° C. lower than the melting point (660 ° C.) of Al,
A thermoelectric conversion module was obtained and the adhesion strength after firing was measured, and the results are shown in Table 1.

Example 4 An oxygen-free Cu plate having a purity of 99.99% by weight was washed with hydrochloric acid and pure water to clean the surface, and then the purity was 99.
Cu particles having 9 wt% and an average particle diameter of about 35 μm (250 mesh under) were sprayed and coated by a normal plasma spraying device. As plasma gas, 20 liters /
Minutes of Ar were used. On the surface-roughened Cu electrode thus obtained, a powder of thermoelectric conversion material was molded in the same manner as in Example 1 and fired to obtain a thermoelectric conversion module, and the adhesion strength after firing was measured. Is shown in Table 1.

(Example 5) In Example 4, except that the metal powder used was replaced by Cu particles, and Ni particles having a purity of 99.9% by weight and an average particle size of about 40 μm (200 mesh under) were used. Firing was performed in the same manner as in Example 4 to obtain a thermoelectric conversion module, and the adhesion strength after firing was measured. The results are shown in Table 1.

(Example 6) In Example 1, after the surface-roughened Cu electrode was produced, 1 was formed by the magnetron sputtering method.
A thermoelectric conversion module was obtained by firing in the same manner as in Example 1 except that Al was evaporated to a thickness of μm, and the adhesion strength after firing was measured. The results are shown in Table 1.

(Example 7) In Example 6, except that W was vapor-deposited instead of Al, firing was performed in the same manner as in Example 6 to obtain a thermoelectric conversion module, and the adhesion strength after firing was measured. The results are shown in Table 1.

(Example 8) In Example 6, except that Mo was vapor-deposited instead of Al, firing was performed in the same manner as in Example 6 to obtain a thermoelectric conversion module, and the adhesion strength after firing was measured. The results are shown in Table 1.

Not only the N-type thermoelectric conversion material as described above, but also the P-type thermoelectric conversion material, the substantially similar results were obtained.

(Comparative Example 1) The thermoelectric conversion module was fired in the same manner as in Example 1 except that the surface-roughened Cu electrode was replaced with a non-surface-roughened Cu electrode. Obtained. The obtained thermoelectric conversion element and the electrode did not have sufficient adhesion strength and were easily peeled off.

(Comparative Example 2) In Example 1, a Cu plate having Cu particles dispersed on its surface was used as the melting point of Cu (1083 ° C.).
The thermoelectric conversion module was obtained by firing in the same manner as in Example 1 except that Cu particles were bonded to the surface of the Cu electrode by performing heat treatment at the above temperature of 1100 ° C. The obtained thermoelectric conversion element and the electrode did not have sufficient adhesion strength and were easily peeled off.

(Comparative Example 3) In Example 1, the Cu particles having an average particle diameter of about 35 μm were replaced with Cu particles having an average particle diameter of 10 μm smaller than the average particle diameter of the powder of the thermoelectric conversion material. Firing was performed in the same manner as in Example 1 to obtain a thermoelectric conversion module. The obtained thermoelectric conversion element and the electrode did not have sufficient adhesion strength and were easily peeled off.

(Comparative Example 4) In Example 4, except that the Cu particles having an average particle diameter of about 35 μm were replaced with Cu particles having an average particle diameter of 10 μm smaller than the average particle diameter of the powder of the thermoelectric conversion material. Firing was performed in the same manner as in Example 4 to obtain a thermoelectric conversion module. The obtained thermoelectric conversion element and the electrode did not have sufficient adhesion strength and were easily peeled off.

[0040]

[Table 1]

As a result of the above, it was found from Table 1 that in the example, a thermoelectric conversion module having a better adhesion strength between the thermoelectric conversion element and the electrode than in the comparative example was obtained.

[0042]

According to the method of manufacturing a thermoelectric conversion module according to claim 1 of the present invention, the average particle size is 10 to 10 on the surface of the electrode.
The metal particles of 200 μm are heat-treated at a temperature lower than the melting point of the metal particles, and a part of the metal particles and the electrode are fused and bonded to each other, so that the surface of the electrode has an increased surface roughness. Since the thermoelectric conversion element powder is molded and fired by using the powder of the thermoelectric conversion material having an average particle diameter smaller than the average particle diameter, an anchor effect can be exerted between the thermoelectric conversion element and the electrode, and thus the adhesion between the thermoelectric conversion element and the electrode can be achieved. A thermoelectric conversion module having excellent strength, high strength and high reliability can be obtained. .

According to the method of manufacturing a thermoelectric conversion module according to claim 2 of the present invention, the average particle size of the metal particles is 20.
Since it is about 150 μm, a thermoelectric conversion module having high strength and high reliability can be obtained.

In the method for manufacturing a thermoelectric conversion module according to claim 3 of the present invention, since the average particle diameter of the powder of the thermoelectric conversion material is 5 to 100 μm, a thermoelectric conversion module having high strength and high reliability can be obtained. .

In the method of manufacturing a thermoelectric conversion module according to claim 4 of the present invention, since the metal particles are at least one selected from the group consisting of Cu, Ni and Al elements, they have high strength and high reliability. A thermoelectric conversion module is obtained.

In the method for manufacturing a thermoelectric conversion module according to the fifth aspect of the present invention, the atmosphere for bonding the metal particles to the electrode surface is a reduced pressure atmosphere, an inert atmosphere or a reducing atmosphere containing hydrogen. Impurity oxygen chemically adsorbed on the powder surface of the conversion material is reduced by hydrogen to prevent diffusion, so that the thermoelectric characteristics of the thermoelectric conversion element are improved, so that a high-strength and highly reliable thermoelectric conversion module can be obtained. .

In the method for manufacturing a thermoelectric conversion module according to claim 6 of the present invention, since the method of bonding the metal particles to the electrode surface is thermal spraying of the metal particles, a thermoelectric conversion module having high strength and high reliability can be obtained. can get.

According to a seventh aspect of the present invention, in the method of manufacturing a thermoelectric conversion module, before the powder of the thermoelectric conversion material is molded on the electrode, Ni, Ni, Since at least one selected from the group consisting of Al, W and Mo elements is coated, Al, Ni,
W and Mo elements react with Cu and thermoelectric conversion element elements,
Further, since a good joint strength is produced, a thermoelectric conversion module having high strength and high reliability can be obtained.

Claims (7)

[Claims] 1. A method of manufacturing a thermoelectric conversion module comprising a thermoelectric conversion element and an electrode, which is obtained by firing a thermoelectric conversion material containing at least two kinds of elements selected from the group consisting of Bi, Te, Se and Sb elements. The surface of the electrode is roughened by heat-treating metal particles having an average particle size of 10 to 200 μm at a temperature lower than the melting point of the metal particles, and fusing and bonding a part of the metal particles and the electrode. A method of manufacturing a thermoelectric conversion module, comprising: forming a powder of the thermoelectric conversion material having an average particle size smaller than the average particle size of the metal particles on an electrode having an increased degree of temperature, and firing the powder. 2. The average particle size of the metal particles is 20 to 150.
The method for manufacturing a thermoelectric conversion module according to claim 1, wherein the thermoelectric conversion module has a thickness of μm. 3. The average particle size of the powder of the thermoelectric conversion material is 5
It is -100 micrometers, The manufacturing method of the thermoelectric conversion module of Claim 1 or Claim 2 characterized by the above-mentioned. 4. The method of manufacturing a thermoelectric conversion module according to claim 1, wherein the metal particles are at least one kind selected from the group consisting of Cu, Ni and Al elements. . 5. The thermoelectric conversion according to claim 1, wherein the atmosphere for bonding the metal particles to the electrode surface is a reduced pressure atmosphere, an inert atmosphere or a reducing atmosphere containing hydrogen. Module manufacturing method. 6. The method for bonding the metal particles to the electrode surface is thermal spraying of the metal particles.
A method for manufacturing the thermoelectric conversion module according to claim 5. 7. Before molding on the electrode using the powder of the thermoelectric conversion material, on the surface of the electrode having the increased surface roughness,
2. Coating with at least one kind selected from the group consisting of Ni, Al, W and Mo elements.
A method for manufacturing a thermoelectric conversion module according to claim 6.