JP5525173B2 - Method and apparatus for manufacturing thermoelectric conversion element - Google Patents

Description

  The present invention relates to a method for manufacturing a thermoelectric conversion element, and more particularly to a method and apparatus for manufacturing a thermoelectric conversion element suitable for manufacturing a thermoelectric conversion element having stable thermoelectric characteristics.

A thermoelectric conversion element using the Seebeck effect can convert heat energy into electric energy. Because this property can be used to convert exhaust heat discharged from industrial and consumer processes and mobile objects into effective power, thermoelectric conversion elements are attracting attention as energy-saving technologies that take environmental issues into consideration.
Such a thermoelectric conversion element is generally configured by joining a plurality of thermoelectric conversion materials (p-type and n-type) with electrodes. The thermoelectric conversion material is produced by filling a sintered material in a space formed by left and right dies and upper and lower punches, and applying a direct current (pulse current) while pressing the space from above and below with a punch. Thus, since the Joule heat is generated by flowing an electric current instead of warming the sintering furnace, the heating can be performed only in a narrow range, the sintering time is shortened, and the temperature unevenness is reduced.

Such pulsed electric current sintering is disclosed in Patent Document 1, for example. And the method of joining and manufacturing a thermoelectric conversion material with an electrode is disclosed by patent document 2, for example (refer especially FIG. 14 of patent document 2).
However, when p-type and n-type thermoelectric conversion materials are provided bonded to electrodes, the resistance value when energized increases if the shape of the thermoelectric conversion material itself is thin. Alternatively, if the material has a large electric resistance, the resistance value is also increased. An increase in resistance means an increase in Joule heat generation. Originally, the interface generates heat and is diffusion-bonded using the magnitude of the interface resistance between the thermoelectric conversion material and the electrode, but the resistance value of the thermoelectric conversion material itself, which is a part other than the interface as described above When becomes large, the thermoelectric conversion material generates significant heat. Such overheating of the thermoelectric conversion material causes breakage or rupture of the thermoelectric conversion material.

JP 2003-46149 A JP 2004-221464 A

  The present invention is based on the above-described prior art, regardless of whether the resistance of the thermoelectric conversion material itself is larger than the interface resistance between the thermoelectric conversion material and the electrode depending on the shape and material of the thermoelectric conversion material. A thermoelectric conversion element manufacturing method that can stably and reliably join the thermoelectric conversion material and the electrode without overheating the thermoelectric conversion material, and can obtain a thermoelectric conversion element with stable thermoelectric characteristics as a result, and An object is to provide an apparatus.

In order to achieve the above object, according to the first aspect of the present invention, an insulating layer is formed on each of the mutually facing inner surfaces of the pressure members made of the conductive material arranged opposite to each other, and an electrode is arranged on the inner surface of the insulating layer. A plurality of thermoelectric conversion materials are interposed between the electrodes, while the pressure member is heated by energizing the pressure member and heating the pressure member, the insulating layer and A method of manufacturing a thermoelectric conversion element that performs bonding to the electrode and bonding of the thermoelectric conversion material and the electrode at the same time , wherein a heat-resistant conductive member is slidably contacted in a pressurizing direction on an outer peripheral portion of the pressing member. The pressure member is slid with respect to the heat-resistant conductive member and is pressed inward while heating the pressure member by energizing the heat-resistant conductive member. A method for manufacturing a thermoelectric conversion element is provided.

According to a second aspect of the present invention, in the first aspect of the present invention, the heat-resistant conductive member has a rod shape, and a plurality of the heat-resistant conductive members are inserted.

The invention of claim 3 is characterized in that, in the invention of claim 1 or 2 , an elastic material is used as the insulating layer.
According to a fourth aspect of the present invention, in the first to third aspects of the present invention, a deformable intermediate layer is provided between the insulating layer and the electrode.
The invention of claim 5 is characterized in that, in the invention of claim 4 , the intermediate layer is made of a metal powder of Cu or Ni.

Moreover, in invention of Claim 6 , it is a manufacturing apparatus of the thermoelectric conversion element used for the manufacturing method of the thermoelectric conversion element in any one of Claims 1-5 , Comprising: The pressurization member distribute | arranged facing, Provided is a thermoelectric conversion element manufacturing apparatus comprising a heat-resistant conductive member slidably inserted in an outer peripheral portion of a pressure member.

According to the first aspect of the present invention, since the insulating layer is formed between the pressure member and the electrode, no current is transmitted in the direction of the electrode even if the pressure member is energized. At this time, when the pressure member is energized, the pressure member is heated, and using this heat, the insulating layer and the electrode are bonded together, and the thermoelectric conversion material and the electrode are bonded simultaneously . Therefore, when the resistance of the thermoelectric conversion material itself is high, regardless of this, the insulating layer, the thermoelectric conversion material, and the electrode can be stably and reliably joined without overheating the thermoelectric conversion material. A thermoelectric conversion element having stable thermoelectric characteristics can be obtained.

Further , since the heat-resistant conductive member is inserted into the outer peripheral portion of the pressure member and slid therewith to pressurize the pressure member in the inner direction, when the heat-resistant conductive member is energized, the current is also transmitted to the pressure member, and the electrode In addition, heat can be generated around the space where the thermoelectric conversion material is arranged, and the electrodes and the thermoelectric conversion material in the space can be heated and pressurized to be diffusion bonded. At this time, since the insulating layer is formed on the inner surface of the pressurizing member, even if the heat-resistant conductive member is energized, this current is not transmitted to the electrode and the thermoelectric conversion material. Therefore, even if the resistance of the thermoelectric conversion material itself is larger than the interface resistance between the thermoelectric conversion material and the electrode depending on the shape and material of the thermoelectric conversion material, the thermoelectric conversion material is stable without being overheated due to energization. Thus, the thermoelectric conversion material and the electrode can be reliably bonded, and as a result, a thermoelectric conversion element having stable thermoelectric characteristics can be obtained.

According to the second aspect of the present invention, by forming the heat-resistant conductive member in a rod shape, the through hole forming process for insertion through the pressure member is simplified, and the workability is improved. Further, by inserting a plurality of heat-resistant conductive members, the space where the electrodes between the pressure members and the thermoelectric conversion material are arranged can be efficiently heated from the surroundings, and the joining efficiency at the time of diffusion joining is improved.
According to the invention of claim 3 , even if the plurality of thermoelectric conversion materials vary in height, the insulating layer is deformed according to the size of the gap and absorbs this. Accordingly, since all the thermoelectric conversion materials can be uniformly pressed with the electrodes, a thermoelectric element having stable thermoelectric characteristics can be obtained.

According to the invention of claim 4 , since the deformable intermediate layer is provided between the insulating layer and the electrode, even if the plurality of thermoelectric conversion materials have height variations, there is no difference between the electrode and the insulating layer. The intermediate layer is deformed according to the gap interval to compensate for this, and all the thermoelectric conversion materials can be uniformly bonded to the electrodes. Therefore, a thermoelectric element having stable thermoelectric characteristics can be obtained.
According to the invention of claim 5 , since the intermediate layer is made of a metal powder of Cu (copper) or Ni (nickel), these metals are highly diffusive, and therefore, the bonding strength is improved by diffusion bonding. Can do.

According to the invention of claim 6 , when the thermoelectric conversion material and the electrode are diffusion-bonded, the heat-resistant conductive member is inserted into the outer peripheral portion of the pressurizing member and is slid to pressurize the pressurizing member in the inner direction. Therefore, when the heat-resistant conductive member is energized, the current is also transmitted to the pressurizing member, which can generate heat around the space where the electrode and the thermoelectric conversion material are arranged, and heat and pressurize the electrode and the thermoelectric conversion material in the space. Diffusion bonding can be performed. At this time, if an insulating layer is provided on the inner surface of the pressure member, this current will not be transmitted to the electrode and the thermoelectric conversion material even if the heat-resistant conductive member is energized. Therefore, even if the resistance of the thermoelectric conversion material itself is larger than the interface resistance between the thermoelectric conversion material and the electrode depending on the shape and material of the thermoelectric conversion material, the thermoelectric conversion material is stable without being overheated due to energization. Thus, the thermoelectric conversion material and the electrode can be reliably bonded, and as a result, a thermoelectric conversion element having stable thermoelectric characteristics can be obtained. That is, by providing the heat-resistant conductive member, it becomes suitable for joining the electrode and the thermoelectric conversion material in an insulated state.

It is a schematic front view of the manufacturing apparatus of the thermoelectric conversion element used for the manufacturing method of the thermoelectric conversion element which concerns on this invention. It is AA sectional drawing of FIG. It is the B section enlarged view of FIG. It is a principal part enlarged view of the manufacturing apparatus of the thermoelectric conversion element used for the manufacturing method of another thermoelectric conversion element which concerns on this invention.

FIG. 1 is a schematic front view of a thermoelectric conversion element manufacturing apparatus used in the method for manufacturing a thermoelectric conversion element according to the present invention, and FIG. 2 is a cross-sectional view taken along line AA of FIG. FIG. 3 is an enlarged view of a portion B in FIG.
As shown in the drawing, the thermoelectric conversion element manufacturing apparatus 1 includes a punch 2 that is a pressurizing member disposed vertically. The punch 2 is made of a conductive material (for example, graphite). Moreover, the punch 2 is 35 mm square-40 mm square, for example, and thickness is 5 mm-6 mm. A plurality (eight in the figure) of rod-like heat-resistant conductive members 7 are inserted into the outer peripheral portion of the punch 2. The punch 2 can slide along the heat-resistant conductive member 7. That is, the punch 2 is pressed inward along the heat-resistant conductive member 7.

  A plurality of thermoelectric conversion materials 3 are disposed between the punches 2 (six thermoelectric conversion materials 3 in FIG. 1). At this time, the thermoelectric conversion material 3 is disposed so that p-type and n-type are alternated. In the case of a thermoelectric conversion material having a pn junction structure, the thermoelectric conversion materials via the electrodes 4 are arranged in the order of pn, that is, so that different thermoelectric properties are adjacent to each other. The thermoelectric conversion material 3 has a length of 2φ of 5 mm to 10 mm, for example, and is arranged in a total of 25 rows of 5 × 5 (in FIG. 2, a total of 36 pieces of 6 × 6 are displayed).

The plurality of thermoelectric conversion materials 3 are connected to the adjacent thermoelectric conversion materials 3 via electrodes 4. This connection is alternately connected above and below the thermoelectric conversion material 3 so that the thermoelectric conversion material 3 is connected in series. For example, copper is used as the electrode 4.
An insulating layer 6 is formed between the punch 2 and the electrode 4. The insulating layer 6 is made of an insulating material having heat resistance (for example, alumina (aluminum oxide), AlN (aluminum nitride), etc.).

  As described above, the insulating layer 6 is disposed on the inner surface of the punch 2, the electrode 4 is disposed on the inner surface, and the thermoelectric conversion material 3 is disposed on the inner surface, thereby preparing the method for manufacturing the thermoelectric conversion element according to the present invention. Complete. Then, while heating the punch 2 by energizing the heat-resistant conductive member 7, the punch 2 is slid with respect to the heat-resistant conductive member 7 and pressed inward, so that the electrode 4 and the thermoelectric conversion material 3 are Diffusion bonding is performed. Thus, since the heat-resistant conductive member 7 is inserted into the outer peripheral portion of the punch 2 and is slid on the punch 2 to press the punch 2 inward, the entire space sandwiched between the punches 2 is heated and heated. be able to. Therefore, even if the electrode 4 is insulated by the insulating layer 6, the electrode 4 and the thermoelectric conversion material 3 can be diffusion bonded by heating and pressurizing. Thus, even if the resistance of the thermoelectric conversion material 3 itself is larger than the interface resistance between the thermoelectric conversion material 3 and the electrode 4 depending on the shape and material of the thermoelectric conversion material 3, the thermoelectric conversion material 3 is energized regardless of this. The thermoelectric conversion material 3 and the electrode 4 can be bonded stably and reliably without being overheated, and as a result, a thermoelectric conversion element having stable thermoelectric characteristics can be obtained. This energization and pressurization is performed in a chamber (not shown) in a vacuum, nitrogen gas or inert gas atmosphere.

  Although the rod-shaped heat-resistant conductive member 7 is shown in the drawing, the rod-shaped heat-resistant conductive member 7 is not particularly limited to a rod-like shape as long as it can slide through the outer peripheral portion of the punch 2. If it is rod-shaped, the through hole forming process for inserting the punch 2 is simplified, and the workability is improved. Moreover, if it is set as the structure which penetrates the multiple heat-resistant electrically-conductive member 7, the space where the electrode 4 between the punches 2 and the thermoelectric conversion material 3 were distribute | arranged can be efficiently heated from the circumference, and the joining efficiency in the case of diffusion joining Will improve. That is, the heat-resistant conductive member 7 may be of any shape as long as it surrounds the space between the punches 2.

Moreover, if an elastic material is used as the insulating layer 6, even if the plurality of thermoelectric conversion materials 3 have height variations, the insulating layer 6 is deformed according to the size of the gap and absorbs this. Therefore, since all the thermoelectric conversion materials 3 can be uniformly pressed with an electrode, a thermoelectric element having stable thermoelectric characteristics can be obtained.
FIG. 4 is an enlarged view of a main part of a thermoelectric conversion element manufacturing apparatus used in another thermoelectric conversion element manufacturing method according to the present invention.

An intermediate layer 5 is further provided between the insulating layer 6 and the electrode 4. The intermediate layer 5 is formed in a deformable state. Therefore, the shape of the punch 2 can be changed so as to be crushed by pressurization. The intermediate layer 5 has a thickness of about 10 μm.
In a state where the intermediate layer 5 is formed, an electric current is passed through the heat-resistant conductive member 7 while pressurizing the punches 2 on both sides in the direction of the thermoelectric conversion material 3, thereby insulating the electrode 4 and the thermoelectric conversion material 3 together. Layer 6 and electrode 4 are diffusion bonded. Thus, even if the intermediate layer 5 is provided, a thermoelectric conversion element is manufactured. By providing the intermediate layer 5, even if the plurality of thermoelectric conversion materials 3 vary in height, the intermediate layer is deformed and compensated for according to the gap distance between the electrode 4 and the insulating layer 6. Thereby, all of the thermoelectric conversion material 3 is uniformly joined to the electrode 4 through the intermediate layer 5, and a thermoelectric conversion element having stable thermoelectric characteristics can be obtained. The intermediate layer 5 may be disposed on both sides of the thermoelectric conversion material 3 or may be disposed on only one side.

In this way, by providing the intermediate layer 5 and diffusion bonding the electrode 4 and the insulating layer 6 to obtain a bonded state, heat is transferred to the high temperature portion and the low temperature portion of the thermoelectric conversion element from the viewpoint of thermal conductivity. Thus, the temperature difference can be increased.
Furthermore, if the intermediate layer 5 is formed of Cu (copper) or Ni (nickel), which is a highly diffusible metal powder, the bonding strength between the electrode 4 and the insulating layer 6 can be improved. That is, when the components are diffused at the interface between the insulating layer 6 and the electrode 4 to form an alloy and are joined together, the higher the diffusibility, the better the joint strength.

  In this case, as a method of forming the intermediate layer 5 with metal powder, there are a method of forming the powder as it is and a method of forming it in a paste form. In the case of forming the powder as it is, the powder is put in an arbitrary mold and is sandwiched between the electrode 4 and the insulating layer 6. Thereby, since the intermediate | middle layer 5 with high diffusibility and a deformation | transformation can be formed, the effect of both the absorption of the height variation of the thermoelectric conversion material 3, and the improvement of a diffusion joining intensity | strength can be acquired.

  Further, when forming the intermediate layer 5 in a paste form, the metal powder is made into a paste form using methyl carbitol, butyl carbitol or the like as a solvent. Also by this, the effect of both the absorption of the variation in the height of the thermoelectric conversion material 3 and the improvement of the diffusion bonding strength can be obtained as in the case where the intermediate layer is formed as a powder. Moreover, since it is only necessary to apply the paste-like intermediate layer 5, the handleability is improved.

  A layer having the same components and configuration as the intermediate layer 5 may be provided between the electrode 4 and the thermoelectric conversion material 3. Thereby, it becomes possible to absorb the height variation of the thermoelectric conversion material 3, and if Cu and Ni are further added, diffusibility can be improved and the joining can be strengthened.

DESCRIPTION OF SYMBOLS 1 Thermoelectric conversion element manufacturing apparatus 2 Punch 3 Thermoelectric conversion material 4 Electrode 5 Intermediate layer 6 Insulating layer 7 Heat-resistant conductive member

Claims (6)

An insulating layer is formed on each of the mutually facing inner surfaces of the pressure member made of a conductive material arranged facing each other,
An electrode is disposed on the inner surface of the insulating layer,
A plurality of thermoelectric conversion materials are interposed between the electrodes,
While heating the pressure member by energizing the pressure member,
A method of manufacturing a thermoelectric conversion element that pressurizes the pressurizing member in an inward direction to simultaneously bond the insulating layer and the electrode and bond the thermoelectric conversion material and the electrode ,
A heat-resistant conductive member is inserted into the outer peripheral portion of the pressure member while being in sliding contact with the pressure direction,
While heating the pressure member by energizing the heat-resistant conductive member,
The said pressurization member is slid with respect to the said heat-resistant electrically-conductive member, and pressurizes inside , The manufacturing method of the thermoelectric conversion element characterized by the above-mentioned . The method of manufacturing a thermoelectric conversion element according to claim 1 , wherein the heat-resistant conductive member has a rod shape and a plurality of the heat-resistant conductive members are inserted. Method for manufacturing a thermoelectric conversion element according to claim 1 or 2, characterized in that said as an insulating layer, using an elastic material. The method for producing a thermoelectric conversion element according to any one of claims 1 to 3 , further comprising a deformable intermediate layer between the insulating layer and the electrode. The method of manufacturing a thermoelectric conversion element according to claim 4 , wherein the intermediate layer is made of a metal powder of Cu or Ni. It is the manufacturing apparatus of the thermoelectric conversion element used for the manufacturing method of the thermoelectric conversion element in any one of Claims 1-5 ,
A pressure member arranged oppositely,
A thermoelectric conversion element manufacturing apparatus comprising: a heat-resistant conductive member slidably inserted in an outer peripheral portion of the pressure member.

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