JP2017050519A - Fesi2-based lamination type thermoelectric conversion module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a FeSi-based lamination type thermoelectric conversion module that can be produced with reduced man-hours and has highly reliable bonding part between a p-type FeSisemiconductor and an n-type FeSisemiconductor.SOLUTION: By alternately filling a p-type FeSipowder 6 and an n-type FeSipowder in a sintering die and sintering to simultaneously perform sintering of the powder and bonding of a p-type FeSielement 12 and an n-type FeSielement 13 during the sintering of the FeSi, an efficient and highly reliable lamination type module can be obtained.SELECTED DRAWING: Figure 6

Description

  The present invention relates to a thermoelectric power generation module that generates power using a temperature difference.

A thermoelectric conversion module using the Seebeck effect is known. The thermoelectric conversion module is generally a thermoelectric conversion element (p-type element) made of a p-type semiconductor and a thermoelectric conversion element (n-type semiconductor) made of an n-type semiconductor on a ceramic substrate. Element) are alternately arranged, and the p-type element and the n-type element are connected in series by electrodes.

The FeSi ₂ -based thermoelectric conversion element is known as a material having a small environmental load.

There has been proposed a method for connecting elements in a state where electric resistance is as low as possible.

  Usually, the p-type element and the n-type element are joined via a metal electrode by means of conductive paste or brazing.

  However, in many cases, the thermoelectric material is a semiconductor, and it is generally difficult to join a metal electrode and a semiconductor element for constituting a module.

  Since each of the p-type element and the n-type element is produced and then joined, there is a problem that the number of man-hours required for production is large.

  In addition, bonding by conductive paste or brazing has a problem that the reliability of the bonded portion is low. In particular, a high reliability is required for a joint portion exposed to a high temperature.

The creation of the p-type element and the n-type element and the joining of the p-type element and the n-type element are performed simultaneously to produce a module having a laminated structure, thereby eliminating the joining process and improving the reliability of the joint.

A graphite mold is alternately filled with p-type FeSi ₂ powder and n-type FeSi ₂ powder, and sintered by a discharge plasma sintering apparatus.
The p-type FeSi ₂ powder is a powder obtained by adding Cr to FeSi ₂ , and the n-type FeSi ₂ powder is a powder obtained by adding CoCr to FeSi ₂ .

After the sintered body obtained after sintering is processed into a hexahedral shape, grooving is performed for the purpose of efficiently increasing the temperature.

In order to facilitate the joining of the element and the electrode (or conductive wire), a metal plate was inserted into the uppermost surface and the lowermost surface of the powder and sintered.

A metal plate may be inserted between the p-type powder and the n-type powder for the purpose of preventing mutual diffusion of each additive element.

  According to the present invention, a conventional p-type element and n-type element are separately processed and then joined with a metal paste or solder, and the joining is completed simultaneously with the sintering of the element, so a joining process is unnecessary. Thus, the manufacturing process can be shortened.

  Metal paste and solder have a problem in reliability. In particular, solder has a problem that it cannot withstand high temperatures such as 600 ° C., but according to the present invention, it can be expected that the heat resistance of the joint is equal to the heat resistance of the element.

Conventional power generation module (two pairs) Manufacturing method of thermoelectric conversion module in embodiment of this invention (sectional drawing at the time of powder filling) Manufacturing method (sintered body) of thermoelectric conversion module in embodiment of this invention Method for manufacturing thermoelectric conversion module in embodiment of the present invention (hexahedral processing step) Method for manufacturing thermoelectric conversion module in embodiment of the present invention (grooving)

Hereinafter, thermoelectric power generation modules according to embodiments of the present invention will be described with reference to the drawings. For comparison, an example of a module according to a conventional method is shown in FIG.

The p-type element 1 and the n-type element 2 are each sintered and then processed into a predetermined shape. The processed p-type element 1 and n-type element are joined to the copper electrode 4 by the metal paste 3. This figure shows two pairs of examples. Thereafter, the upper and lower sides are sandwiched between ceramic insulating plates 5 and used as a thermoelectric power generation module.

FIG. 2 is a cross-sectional view showing a powder filling state for simultaneous sintering and joining of elements in the present invention. The p-type FeSi ₂ powder 6 and the n-type FeSi ₂ powder 7 were alternately filled into a space composed of a graphite die 8 and a graphite lower punch 9 having an inner diameter of φ20 in five layers. The amount of powder was estimated to be about 3.5 mm after each layer was sintered.

At this time, the silver plate 10 was filled in the uppermost surface and the lowermost surface for the purpose of providing a metal layer for facilitating the joining of the p-type element and the n-type element to the lead wire for taking out electric power.

Thereafter, the upper punch 11 was inserted and sintered by a discharge plasma sintering machine. The temperature at which the sintering is performed is, for example, 750 ° C., and the pressure applied to the upper and lower punches is, for example, 70 MPa.

The sintered body is shown in FIG. A sintered body having a diameter of 20 mm and a height of about 35 mm was obtained.

FIG. 4 shows the sintered body shown in FIG. 3 which has been processed into a size of 15 mm × 11 mm on the surface of φ20. A hexahedron of 15 mm × 11 mm × 35 mm was obtained.

As shown in FIG. 5, groove processing 14 having a width of 1 mm and a depth of 10 mm was performed on the hexahedron of FIG. 4 along the interface between the p-type element and the n-type element alternately in the 15 mm direction.

The lead wire 15 was soldered to the processed body obtained in FIG. 5 and sandwiched between the ceramic insulating plates 5 to obtain the module shown in FIG. At this time, the conducting wire and the Ag layer can be easily soldered and joined at the low temperature side, so there is no problem of heat resistance.

DESCRIPTION OF SYMBOLS 1 p-type element 2 n-type element 3 Conductive paste, brazing material, etc. 4 Electrode 5 Insulating ceramics 6 p-type FeSi ₂ powder 7 n-type FeSi ₂ powder 8 Graphite die 9 Graphite lower punch 10 Silver plate 11 Graphite upper punch 12 p-type FeSi ₂ element 13 n-type FeSi ₂ element 14 Groove machining 15 Conductor

  The present invention relates to a thermoelectric power generation module that generates power using a temperature difference.

A thermoelectric conversion module using the Seebeck effect is known. The thermoelectric conversion module is generally a thermoelectric conversion element (p-type element) made of a p-type semiconductor and a thermoelectric conversion element (n-type semiconductor) made of an n-type semiconductor on a ceramic substrate. Element) are alternately arranged, and the p-type element and the n-type element are connected in series by electrodes.

The FeSi ₂ -based thermoelectric conversion element is known as a material having a small environmental load.

There has been proposed a method for connecting elements in a state where electric resistance is as low as possible.

  Usually, the p-type element and the n-type element are joined via a metal electrode by means of conductive paste or brazing.

  However, in many cases, the thermoelectric material is a semiconductor, and it is generally difficult to join a metal electrode and a semiconductor element for constituting a module.

  Since each of the p-type element and the n-type element is produced and then joined, there is a problem that the number of man-hours required for production is large.

  In addition, bonding by conductive paste or brazing has a problem that the reliability of the bonded portion is low. In particular, a high reliability is required for a joint portion exposed to a high temperature.

The creation of the p-type element and the n-type element and the joining of the p-type element and the n-type element are performed simultaneously to produce a module having a laminated structure, thereby eliminating the joining process and improving the reliability of the joint.

A graphite mold is alternately filled with p-type FeSi ₂ powder and n-type FeSi ₂ powder, and sintered by a discharge plasma sintering apparatus.
The p-type FeSi ₂ powder is a powder obtained by adding Cr to FeSi ₂ , and the n-type FeSi ₂ powder is a powder obtained by adding CoCr to FeSi ₂ .

After the sintered body obtained after sintering is processed into a hexahedral shape, grooving is performed for the purpose of efficiently increasing the temperature.

In order to facilitate the joining of the element and the electrode (or conductive wire), a metal plate was inserted into the uppermost surface and the lowermost surface of the powder and sintered.

A metal plate may be inserted between the p-type powder and the n-type powder for the purpose of preventing mutual diffusion of each additive element.

  According to the present invention, a conventional p-type element and n-type element are separately processed and then joined with a metal paste or solder, and the joining is completed simultaneously with the sintering of the element, so a joining process is unnecessary. Thus, the manufacturing process can be shortened.

  Metal paste and solder have a problem in reliability. In particular, solder has a problem that it cannot withstand high temperatures such as 600 ° C., but according to the present invention, it can be expected that the heat resistance of the joint is equal to the heat resistance of the element.

Conventional power generation module (two pairs) Manufacturing method of thermoelectric conversion module in embodiment of this invention (sectional drawing at the time of powder filling) Manufacturing method (sintered body) of thermoelectric conversion module in embodiment of this invention Method for manufacturing thermoelectric conversion module in embodiment of the present invention (hexahedral processing step) Method for manufacturing thermoelectric conversion module in embodiment of the present invention (grooving) Manufacturing method of thermoelectric conversion module in embodiment of the present invention (complete drawing)

Hereinafter, thermoelectric power generation modules according to embodiments of the present invention will be described with reference to the drawings. For comparison, an example of a module according to a conventional method is shown in FIG.

The p-type element 1 and the n-type element 2 are each sintered and then processed into a predetermined shape. The processed p-type element 1 and n-type element are joined to the copper electrode 4 by the metal paste 3. This figure shows two pairs of examples. Thereafter, the upper and lower sides are sandwiched between ceramic insulating plates 5 and used as a thermoelectric power generation module.

FIG. 2 is a cross-sectional view showing a powder filling state for simultaneous sintering and joining of elements in the present invention. The p-type FeSi ₂ powder 6 and the n-type FeSi ₂ powder 7 were alternately filled into a space composed of a graphite die 8 and a graphite lower punch 9 having an inner diameter of φ20 in five layers. The amount of powder was estimated to be about 3.5 mm after each layer was sintered.

At this time, the silver plate 10 was filled in the uppermost surface and the lowermost surface for the purpose of providing a metal layer for facilitating the joining of the p-type element and the n-type element to the lead wire for taking out electric power.

Thereafter, the upper punch 11 was inserted and sintered by a discharge plasma sintering machine. The temperature at which the sintering is performed is, for example, 750 ° C., and the pressure applied to the upper and lower punches is, for example, 70 MPa.

The sintered body is shown in FIG. A sintered body having a diameter of 20 mm and a height of about 35 mm was obtained.

FIG. 4 shows the sintered body shown in FIG. 3 which has been processed into a size of 15 mm × 11 mm on the surface of φ20. A hexahedron of 15 mm × 11 mm × 35 mm was obtained.

As shown in FIG. 5, groove processing 14 having a width of 1 mm and a depth of 10 mm was performed on the hexahedron of FIG. 4 along the interface between the p-type element and the n-type element alternately in the 15 mm direction.

The lead wire 15 was soldered to the processed body obtained in FIG. 5 and sandwiched between the ceramic insulating plates 5 to obtain the module shown in FIG. At this time, the conducting wire and the Ag layer can be easily soldered and joined at the low temperature side, so there is no problem of heat resistance.

DESCRIPTION OF SYMBOLS 1 p-type element 2 n-type element 3 Conductive paste, brazing material, etc. 4 Electrode 5 Insulating ceramics 6 p-type FeSi ₂ powder 7 n-type FeSi ₂ powder 8 Graphite die 9 Graphite lower punch 10 Silver plate 11 Graphite upper punch 12 p-type FeSi ₂ element 13 n-type FeSi ₂ element 14 Groove machining 15 Conductor

Claims (5)

In a FeSi ₂ -based thermoelectric power generation module, a p-type element and an n-type element have a laminated structure. 2. The method according to claim 1, wherein the p-type element and the n-type element are joined by a discharge plasma sintering method. 2. The method according to claim 1, wherein each of the p-type element and the n-type element is sintered and the elements are joined together by a discharge plasma sintering method. 2. The structure according to claim 1, wherein the p-type element and the n-type element have a slit structure at the interface. In Claim 1, it has a metal layer for making it easy to join an electrode (copper wire) to both end faces.

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