JPH06268264A - Manufacture of peltier element - Google Patents

Abstract

PURPOSE:To enable a diffusion preventing layer and an electrode layer to be provided excellent in adhesion inside a sintered body in one piece by a method wherein material powder is co-ground, mixed together, and molded into a body, a diffusion preventing layer and an electrode layer are laminated on both the end faces of the molded body, and the molded body provided with the diffusion preventing layers and the electrode layers are sintered by plasma. CONSTITUTION:Thermoelectric conversion material material powder is co-ground and mixed, and electrode layer b-2 forming powder, for instance, copper powder is filled so as to obtain an electrode layer b-2 prescribed in thickness on a lower punch 3 along a mold in a PAS apparatus. The same as above, diffusion preventing layer forming powder, for instance, nickel powder is filled. Then, a prescribed amount of material power co-ground and mixed is filled. Furthermore, a diffusion preventing layer b-1 and an electrode layer b-2 are laminated, and then the upper and the lower punch, 2 and 3, are clamped to mold the laminated molding powder layers into a body, and the molded body is sintered by plasma. By this setup, molding, sintering, and formation of conductive layers B are carried out at a time, so that a Peltier element can be manufactured high in efficiency.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing a Peltier device. More specifically, the present invention relates to a method for efficiently manufacturing a Peltier element having excellent thermoelectric properties and having a strongly adhered conductive layer including a diffusion prevention layer and an electrode layer, by simplifying the process. .

[0002]

2. Description of the Related Art A Peltier element is an element utilizing the Peltier effect, and has a function of converting electric power into heat energy by flowing a current between the elements and controlling temperature. It is a thing. Peltier devices having such characteristics are devices that generate heat,
In particular, by being used by being bonded to a semiconductor element, the heat of the semiconductor element is removed and the temperature is maintained at a constant temperature, which contributes to stabilization of the performance of the semiconductor element and has a simple structure and easy handling. Since then, it has been widely used.
The process for manufacturing this Peltier element is generally a method in which a sintered body made of a thermoelectric conversion material is manufactured, and then a diffusion prevention layer such as a nickel layer is applied, and an electrode material such as a copper plate is soldered to this. Alternatively, a method such as providing a metal vapor deposition layer having the above-mentioned function on the sintered body is adopted. The Peltier element obtained in this way is a sintered body made of a thermoelectric conversion material or exfoliation of the diffusion preventive layer due to the difference in the coefficient of thermal expansion when a drastic temperature change occurs during the soldering process during assembly or during use. It can be damaged. As a method of solving such a problem, for example,
Japanese Patent Application Laid-Open No. 4-249385 discloses an improved technique. Here, in the thermoelectric conversion element, when the arithmetic average of the length of one side of the element cross section is b, the nickel layer thickness t is configured to satisfy the equation of b / t ≦ 100, Methods have been proposed to prevent damage and dropout. However, this proposed method has the disadvantages that the nickel layer has a large film thickness, the thermal conductivity is disadvantageous, and the adhesion of the nickel layer on the device surface is not sufficient. Therefore, recently, the Peltier device is required to have further improved performance and at the same time, it is required to reduce the cost, and the development of an efficient manufacturing method thereof is demanded.

[0003]

Therefore, the present inventors have
By eliminating the drawbacks of the conventional method, it has excellent thermoelectric properties,
We have conducted intensive research to develop a Peltier element manufacturing method that can efficiently manufacture a Peltier element with excellent adhesion between a sintered body made of thermoelectric conversion material and a conductive layer at a low cost by simplifying the process. It was As a result, it is possible to cover the conductive layer at the same time as the production of the sintered body, by co-milling and mixing the raw material powders, molding, laminating the conductive layer on the molded body, and simultaneously sintering these. , It was found that an element having the above characteristics can be obtained while simplifying the process. The present invention has been completed based on such findings.

That is, according to the present invention, in a method of manufacturing a Peltier device having conductive layers at both ends of a sintered body made of a thermoelectric conversion material, raw material powder of the thermoelectric conversion material used for the sintered body is co-ground. A method for manufacturing a Peltier device, characterized in that, after mixing, raw material powders that have been co-ground and mixed are molded, and conductive layers are laminated on both ends of the obtained molded body and plasma-sintered. .

In the Peltier element, conductive layers are provided on both end surfaces of a sintered body made of a thermoelectric conversion material. In the manufacturing method of the present invention, both ends of a molded body made of a thermoelectric conversion material before the sintered body is obtained. It is characterized in that a conductive layer is laminated on the surface and then sintered. As a result, the conductive layer can be integrally provided at the same time as the sintering of the molded body, the manufacturing process can be simplified, and a Peltier element excellent in the adhesive force of the conductive layer to the sintered body can be obtained. In order to manufacture the Peltier element in which the conductive layer is strongly and integrally provided as described above, in the manufacturing method of the present invention, first, a molded body made of a thermoelectric conversion material is manufactured. The molded body made of this thermoelectric conversion material is manufactured by various methods. First, the raw material powder of the thermoelectric conversion material is co-ground and mixed. In the present invention, the raw material powder of the thermoelectric conversion material is widely selected and used from metal particles such as bismuth, tellurium, antimony, selenium, germanium, silicon, lead or iron. Moreover, a dopant is compounded and used as needed. Here, as the dopant, for example, iodine, bromine, germanium, tin, lead, silver, mercury, indium, manganese, cobalt,
Examples thereof include chromium, copper and halides of these elements. These raw material powders are composed of at least two kinds of metals (elements) selected from the above metal particles and dopants, and the raw material powders having an average particle diameter of 0.05 to 100 μm are used. Then, these metal particles are mixed at an appropriate ratio and co-ground and mixed, and the composition thereof is, for example, (Bi ₂ Te ₃ ) _x (Sb ₂ Te ₃ ) _1-x [wherein, x is It is a value that satisfies 0 <x <0.95. ] The composition represented by this is prepared. In addition to this, for example, the following composition is prepared. 1) (Bi ₂ Te ₃ ) _1-x (Bi ₂ Se ₃ ) _x [In the formula, x is a value satisfying 0 <x <0.95. 2) PbTe + PbI ₂ / Na 3) Si _0.800 Ge _0.200 + GaP / B 4) Fe _0.92 Mn _0.08 Si _2.00 5) Fe _0.95 Co _0.05 Si _2.00

For co-grinding and mixing of the raw material powder, the metal particles are mixed at an appropriate ratio and co-pulverized and mixed to be sufficiently mixed. At this time, it is desirable to further advance the mixing and pulverization at the same time to further reduce the particle size of the raw material. In this case, the co-pulverization / mixing can be performed by means such as a ball mill, an impact fine pulverizer, a jet pulverizer, a tower friction machine, and the like for simultaneously performing the pulverization and mixing. Among these means, it is preferable to use a ball mill, especially a planetary type high-intensity ball mill rather than a drop type. The state of mixing may be either dry or wet. For example, in the case of a wet kiln, alcohols such as ethanol and butanol and various solvents may be used as a mixing aid. You can The mixing force and mixing time for the above co-milling / mixing are
It is desirable to set the average particle diameter of the raw material powder after mixing to be about 0.05 to 100 μm, preferably about 0.05 to 30 μm. Here, if the particle size exceeds 100 μm,
This is not preferable because it causes deterioration of uniformity. Further, the particle size of the raw material powder is preferably small, but a large amount of energy is consumed in order to reduce the particle size to 0.05 μm or less.
About 0.05 to 100 μm is sufficient.

Next, in the method of the present invention, the raw material powder (fine powder) co-ground and mixed as described above is molded. In this molding, the raw material powder co-crushed and mixed,
For example, PAS (Plazma Activated S
molding using an intering device. In the above PAS device, the electrode layer powder, the diffusion prevention layer powder and the raw material powder, or their thin plates are put in a mold that constitutes the device, and a conductive layer is simultaneously laminated on both end surfaces of the molded body, and then plasma is formed. Sintering simplifies the process and makes it possible to efficiently manufacture a Peltier element in which a conductive layer is integrally and strongly adhered to the surface of a molded body.

It is also possible to form the co-pulverized and mixed raw material powder, and to form metal powder for the diffusion prevention layer and the electrode layer in advance to form a thin layered body, and laminate and plasma sinter. In this case, in order to shape the co-crushed and mixed raw material powder, a desired shape such as press molding or cold isostatic pressing (CIP molding) can be applied under normal pressure or pressure. , Diameter 2-200mm, length 2-200
It can be pressure-molded into a rod shape of mm or a prism. This pressure molding can be performed by adding a binder component such as polyvinyl alcohol, if necessary.
The pressure during the pressure molding is different depending of the raw material powder types and particle sizes, usually, 0.2~20ton / cm ^2, preferably 0.5~15ton / cm ^2. As the molding method, extrusion molding or injection molding can be adopted in addition to the above pressure molding. Further, as the method for forming the diffusion prevention layer and the electrode layer, any forming method such as coating or screen printing can be adopted.

Next, a Peltier element can be obtained by plasma-sintering the laminate obtained above.
That is, in the PAS apparatus of FIG. 1, powder for electrode layer formation, for example, copper powder, is weighed and placed along the die on the lower punch so that an electrode layer having a predetermined thickness can be obtained. Similarly, a powder for forming the diffusion prevention layer, for example, nickel powder is weighed and put. Next, a predetermined amount of the above-mentioned co-ground and mixed raw material powder is weighed and put. Further, when the diffusion prevention layer and the electrode layer are laminated in the same manner as above, the upper punch is tightened and formed, and then the plasma is sintered, the forming and the sintering and the formation of the conductive layer can be performed at the same time. Such a Peltier device can be efficiently manufactured. In addition, using the raw material powder co-pulverized and mixed as described above, a diffusion preventive layer is formed on the molded body obtained in advance so that a diffusion preventive layer and an electrode layer having a predetermined thickness can be obtained. The Peltier device can also be manufactured by stacking layers of powder for use, for example, nickel powder and electrode layer forming powder, for example, copper powder, and then performing plasma sintering.

Here, in the plasma sintering process capable of simultaneously performing molding and sintering, as described above, the raw material powder, the diffusion preventing layer forming powder and the electrode layer forming powder are put into a mold and pressurized. , In a reducing atmosphere of hydrogen gas or inert gas,
For example, it is carried out in an atmosphere of argon, nitrogen, or a mixed gas thereof, or in the air. The sintering temperature is appropriately selected depending on the kind of raw material powder, composition ratio and the like, but it can be usually performed in the range of 100 to 3,000 ° C. After reaching the sintering peak temperature, the temperature is maintained for a predetermined time and the molded body is sintered to obtain the target thermoelectric conversion material.

In the plasma sintering process, the sintering pressure is 1
~ 1,000 tonf, preferably 2-500 tonf
And also with an input density of 1 to 500 kW / cm ³ , preferably 5 to 200 kW / cm ³ . In this plasma sintering process, by setting the input density to be 1 to 500 kW / cm ³ , the low power of several tens of kilowatts is used for molding under a low pressure of several tons, the electrode is brought into contact with the powder, and By utilizing electric discharge, a sintering time is shorter than that of the conventional high frequency hot pressing method, and it is possible to efficiently obtain a sintered body with much better homogeneity. Then, only by molding, it is possible to perform molding and sintering at a melting point or less at the same time. By performing the plasma sintering in this manner, the sintering time is about 10 minutes, which is significantly shorter than that of the conventional method, and the productivity can be significantly improved. For the diffusion prevention layer, for example, powder of nickel, chromium, tungsten, molybdenum or the like having a particle size of 0.5 to 100 μm can be used. Further, for the electrode layer, for example, a powder of copper, aluminum, gold, silver or the like having a particle size of 0.5 to 100 μm can be used. A plate-like material may be used for these diffusion prevention layers and electrode layers instead of the respective powders. Then, the diffusion prevention layer and the electrode layer are usually laminated in a thickness of 0.5 to 2,000 μm. An example of the combination of the thermoelectric conversion material, the diffusion prevention layer and the electrode layer and the sintering conditions are shown in Table 1.

[0012]

[Table 1]

[0013]

[Table 2]

As described above, in the Peltier element obtained by the present invention, by using the co-milled and mixed raw material powders, the co-pulverized and mixed raw material powders are uniformly mixed and made into fine particles, or the mechanical powder is mechanically mixed. Because of the alloying effect at the atomic level due to the ing effect, the sintered body becomes uniform and has excellent thermoelectric properties. At the same time, since the diffusion prevention layer and the electrode layer can be strongly bonded together, a Peltier element having excellent mechanical strength can be obtained. Then, the manufacturing method of the present invention, by plasma sintering, compared with the conventional method that goes through the melting process of growing a single crystal,
Since the molding and the sintering can be performed at the same time, the manufacturing process is greatly simplified, and the sintering can be performed in a short time by the plasma sintering, so that the Peltier device can be manufactured very efficiently.

[0015]

The present invention will be further described in detail with reference to examples, but the present invention is not limited to these examples. Example 1 A raw material powder of a system composed of (Bi ₂ Te ₃ ) _0.15 (Sb ₂ Te ₃ ) _0.85 + Sb (5% by weight) was prepared. 100g of this raw material powder
Ethanol was added at a rate of 1 ml / g to a planetary wet ball mill (ball diameter: 10 mm x 50 pieces), and 2
Co-grinding and mixing was performed for 0 hours. The average particle size of the obtained powder raw material was about 1.2 μm. The co-pulverized and mixed powder raw material was put into a mold in a predetermined amount so that the diameter was 20 mm and the length was 20 mm. Then, as a raw material powder for the diffusion prevention layer, nickel powder having a particle size of about 3.0 μm was weighed so as to have a thickness of 20 μm, and subsequently, copper powder having a particle size of about 3.0 μm was made to have a thickness of 300 μm. After weighing and laminating on both end faces, plasma sintering was performed at 300 kfg and 773 K for about 10 minutes. The contact resistance with the obtained sintered body was measured.
The measurement results are shown in Table 2 together with the thermoelectric characteristics.

Example 2 Example 1 was repeated except that a nickel plate having a thickness of 20 μm and a copper plate having a thickness of 300 μm were used instead of the nickel powder and the copper powder for the diffusion prevention layer. did. The contact resistance with the obtained sintered body was measured. The measurement results are shown in Table 2 together with the thermoelectric characteristics.

[0017]

[Table 3]

Z (performance index) = α ² / ρκ,
α: Seebeck coefficient, ρ: resistivity, κ: thermal conductivity. Rr is a contact resistance.

[0019]

As described above, the raw material powders are co-pulverized and mixed, the diffusion prevention layer and the electrode layer are laminated on both surfaces of the molded body, and plasma-sintered. The electrode layer can be strongly provided with good adhesiveness and integrally provided, and a Peltier element can be efficiently obtained. Therefore, the Peltier device according to the manufacturing method of the present invention,
Excellent performance, solid-state image sensor (CCD), laser diode, light emitting diode, infrared detector, microwave detector, high resolution spectrometer (Si, Ge), CPU board,
LSI substrate, parametric amplifier, microwave transistor amplifier, PbEuTe laser (4 to 5.5μ
m), two-dimensional CIP array, CO ₂ laser detector, C
oMgF ₂ laser (1.5-2.3 μm), cooling of sample holder for powder analysis of X-ray diffractometer, cooling of sample holder for Raman spectroscopy, military generator (portable, submarine), vehicle-mounted generator When applied to (cars, trains, etc.),
The effect can be expected sufficiently.

[Brief description of drawings]

FIG. 1 is a perspective view showing a method of manufacturing a Peltier device according to the present invention.
It is an example of a schematic diagram for explaining plasma sintering.

FIG. 2 is an example of a schematic view showing a Peltier device obtained by the manufacturing method of the present invention.

[Explanation of symbols]

 1: Mold 2: Upper punch 3: Lower punch 4: Upper electrode 5: Lower electrode A: Sintered body of thermoelectric conversion material B: Conductive layer b-1: Diffusion prevention layer b-2: Electrode layer l: Element length Φ: diameter

Claims (1)

[Claims] 1. A method of manufacturing a Peltier element having a conductive layer at both ends of a sintered body made of a thermoelectric conversion material, wherein after co-pulverizing and mixing raw material powder of the thermoelectric conversion material used for the sintered body, A method for manufacturing a Peltier element, which comprises molding the co-pulverized and mixed raw material powder, laminating a conductive layer on both ends of the obtained molded body, and performing plasma sintering.