JPH10321920A - Thermoelectric transducer - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric transducer which can absorb the difference in the coefficients of thermal expansion for a semiconductor layer and an electrode, and ensure bonding strength. SOLUTION: A thermoelectric transducer has at least numerous semiconductor layers 35, 36 and numerous electrodes 34, 37 for electrically connecting the respective semiconductor layers 35, 36. The electrodes 34, 37 have semiconductor bonding regions 40 in the vicinity of both end portions. Between the semiconductor bonding regions 40, a first notched part 50a which stretches from one side edges of the electrodes 34, 37 towards the other side edges, and a second notched part 50b, which stretches from the other side edges of the electrodes 34, 37 towards the one side edges and are formed at a position shifted from the first notched part 50a, are arranged. A current flowing part 51 which is narrow is formed between the first notched part 50a and the second notched part 50b.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelectric conversion device used as an electronic cooling device or a power generation device, and more particularly, to a thermoelectric conversion device which has little performance deterioration even after repeated thermal cycles, has excellent operation reliability, and has a long service life. Related to the device.

[0002]

2. Description of the Related Art FIG. 9 is a sectional view of a conventional heat converter. In the drawing, reference numeral 100 denotes a heat absorbing side substrate made of ceramic, 1
Reference numeral 01 denotes a heat dissipation side substrate also made of ceramic, 102 denotes a heat absorption side electrode made of copper, 103 denotes a heat dissipation side electrode also made of copper, 10
4 is an N-type semiconductor layer and 105 is a P-type semiconductor layer.

As shown in FIG. 1, an N-type semiconductor layer 104 and a P-type semiconductor layer 105 are integrally joined to a heat-absorbing electrode 102 and a heat-radiating electrode 103 via a solder layer (not shown).

[0004]

Incidentally, since the semiconductor layer and the electrode have greatly different coefficients of thermal expansion, during repeated use, the difference in the coefficient of thermal expansion causes the difference in the coefficient of thermal expansion in the horizontal direction of the bonding surface (double arrow in FIG. 11). (A direction), a shift (stress) occurs, the bonding strength (adhesion) decreases, and in extreme cases, a part of the bonding may peel off. When a part of the junction between the semiconductor layer and the electrode is peeled off as described above, there is a problem that the thermal resistance of the junction increases and the thermoelectric conversion characteristics are extremely reduced.

The present invention solves the above-mentioned disadvantages of the prior art,
By providing a thermoelectric conversion device that absorbs the difference between the thermal expansion coefficients of the semiconductor layer and the electrode and maintains the bonding strength at all times, there is little performance degradation even after repeated thermal cycling, excellent operation reliability, and long service life. The purpose is to:

[0006]

In order to achieve the above object, the present invention comprises a number of semiconductor layers and a number of electrodes for electrically connecting the respective semiconductor layers, wherein at least one of the aforementioned semiconductor layers is provided. In one thermoelectric conversion device of the skeleton type, at least a part of the plurality of electrodes has a semiconductor junction region near both ends, and between the semiconductor junction regions, from one side edge of the electrode to the other. A first notch extending toward the side edge of the electrode, and a second notch extending from the other side edge of the electrode toward one side edge and formed at a position offset from the first notch. And a narrow conducting portion is formed between the first notch and the second notch.

[0007]

Next, an embodiment of the present invention will be described with reference to the drawings. 1 to 4 are views for explaining the first embodiment. FIG. 1 is a cross-sectional view of a thermoelectric converter used as an electronic cooling device such as an electronic refrigerator, and FIG. 2 is used for the thermoelectric converter. Bottom view of the first heat dissipation side frame
FIG. 3 is a partially enlarged cross-sectional view showing a lead wire take-out structure,
FIG. 4 is an enlarged sectional view of a main part of the element block.

As shown in FIG. 1, the thermoelectric converter comprises a box-shaped heat absorbing member 1 disposed on the side to be cooled, for example, inside a refrigerator, a heat absorbing side heat exchange base 2, a thermoelectric conversion element group 3, ,
A heat-dissipation-side heat exchange base 4, a first heat-dissipation-side frame 6-1;
It is mainly composed of the heat radiation side frame 6-2 and the dispersion member 7.

The heat absorbing member 1 is composed of a fin base having a large area, and is provided with a large number of heat absorbing fins (not shown). A fan can be provided in the vicinity as needed.
The heat absorbing member 1 may be integral with the heat absorbing fin, or may not have the heat absorbing fin.

The heat-absorbing heat-exchange substrate 2 and the heat-dissipating heat-exchange substrate 4 are both made of a metal having good thermal conductivity, such as aluminum. (See FIG. 4). When the alumite insulating film 33 is formed by the anodizing method, the sealing property with the thermoelectric conversion element group 3 via the thin film 38 described later is better if the insulating film 33 is not sealed. The insulating film 33 can also be formed by thermal spraying or the like. As shown in FIG. 1, the heat-absorbing-side heat exchange base 2 is formed of a thick block body to ensure a good cooling state.

As shown in FIG. 4, the thermoelectric conversion element group 3 includes a heat absorbing side electrode 34, a heat radiating side electrode 37, both electrodes 34,
It is mainly composed of a large number of P-type semiconductor layers 35 and N-type semiconductor layers 36 arranged between 37. The P-type semiconductor layer 35 and the N-type semiconductor layer 36 are structurally and thermally arranged in parallel, but are electrically connected in series via the electrodes 34 and 37.

As shown in FIG. 1, the first heat absorbing side frame 6-1 is arranged from the heat radiating side heat exchange base 4 to the heat absorbing side heat exchange base 2 side. The upper and lower portions are hollow, and have a base end 6-1a and an extension 6 extending downward from the inner periphery of the base end 6-1a.
-1b, and the cross-sectional shape is substantially stepped. The base end 6-1a is liquid-tightly joined to a peripheral portion of the lower surface of the heat-radiation-side heat exchange base 4 by using, for example, an adhesive or an O-ring and an adhesive.

As described above, the heat-absorbing heat-exchange substrate 2 is formed of a thick block body. The extended portion 2a extends substantially along. The extended portion 2a of the heat-absorbing side heat exchange base 2 and the first heat-absorbing side frame 6
-1b are substantially parallel to each other, and the heat-absorbing-side heat exchange base 2 is bonded by the adhesive 14 injected therebetween.
And the first heat absorbing side frame 6-1 are integrally joined. As the adhesive 14, a curable adhesive such as an epoxy-based or acrylic-based adhesive, or a fusion-bonded adhesive such as a hot-melt-based adhesive can be applied.

A plurality of positioning pins 26 are inserted between the extending portion 2a and the extending portion 6-1b, and the heat absorbing side heat exchange base 2 and the first heat absorbing base 2 before the adhesive 14 is completely cured. It prevents relative displacement with the side frame 6-1. 6-1d shown in FIG. 2 is a pin insertion hole formed in the extension 6-1b.

A base end 6-1 is provided outside the extension 6-1b.
A plurality (four in the present embodiment) of reinforcing ribs 6-1c extending to the side a are provided integrally. As shown in FIG. 1, the first heat absorbing side frame 6-1 is disposed so as to straddle the heat absorbing side heat exchange base 2 and the heat radiation side heat exchange base 4. There is a return of heat through one. In order to minimize this heat return, the first heat absorbing side frame 6
Although it is better to mold -1 relatively thin, the mechanical strength of the first heat-absorbing side frame 6-1 decreases if the molding is thin. Therefore, in the present embodiment, the base portion 6-1a and the extension portion 6-1 are used.
A plurality of reinforcing ribs 6-1c are provided between b to maintain the rigidity of the first heat absorbing side frame 6-1.

Further, by forming a step-like shape, that is, a non-linear shape, between the base end portion 6-1a and the extending portion 6-1b, the first
A long creepage distance from the heat-absorbing heat exchanging base 2 to the heat-dissipating heat exchanging base 4 of the heat-absorbing side frame 6-1 is ensured to be long, so that heat returning through the first heat-absorbing side frame 6-1 is reduced. ing.

As shown in FIG. 2 and FIG.
-1a is formed at a predetermined position, and a lead wire extraction groove 6-1e is formed, and the lead wire 19 connected to the electrode 34 of the thermoelectric conversion element group 3 is drawn out from the extraction groove 6-1e, and the lead groove 6-1e is formed.
1e and the lead wire 19 are sealed gas-liquid-tight with a sealant 27.

The second heat-dissipating frame 6-2 is disposed above the heat-dissipating heat-exchanging base 4 and is substantially hollow at the top and open at the bottom. It is liquid-tightly adhered to the peripheral portion of the upper surface of the heat-dissipating-side heat exchange base 4 via the heat sink. A water supply pipe portion 9 is provided substantially at the center of the second heat radiation side frame 6-2.
However, a drain pipe section 10 is provided near the periphery.

The dispersing member 7 is provided with a peripheral wall 7a, a bottom wall 7b connected to the lower end of the peripheral wall 7a, and a number of nozzles 7e extending from the bottom wall 7b to the heat exchange base 4 on the heat radiation side. Dispersion holes 7d are formed in the nozzle portion 7e.

By fixing the dispersion member 7 in the second heat radiation side frame 6-2, a flat first space 11 is formed on the water supply pipe 9 side of the dispersion member 7, and the dispersion member 7 has a heat radiation side. A flat second space 13 is formed on the heat exchange base 4 side, and a drainage channel 12 that connects the second space 13 and the drain pipe portion 10 is formed.

As shown in FIG. 1, water 15 as a heat transfer medium
Is supplied from the central water supply pipe portion 9 and spreads all at once in the first space portion 11, and is jetted from each nozzle portion 7 e (dispersion hole 7 d) toward the upper surface of the heat-dissipation-side heat exchange base 4. The water 15 colliding with the heat-radiation-side heat exchange base 4 and removing the heat of the heat-radiation-side heat exchange base 4 diffuses in the second space 13 having a narrow gap, and is discharged from the drain pipe 10 through the drainage channel 12 to the outside of the system. Is done. The discharged water 15 is cooled by a radiator (not shown) or natural cooling, and is reused through a forced circulation system.

A heat insulating material 28 shown in FIG. 1 is installed so as to cover the outer peripheral portions of the first heat radiation side frame 6-1, the heat radiation side heat exchange base 4 and the second heat radiation side frame 6-2. I have.

In this embodiment, the first radiating side frame 6-1 and the second radiating side frame 6-2 are provided separately.
The heat radiation side frame 6-1 and the second heat radiation side frame 6-2 can be formed integrally, or the heat radiation side heat exchange base 4 and the second heat radiation side frame 6-2 can be formed integrally. is there.

FIG. 4 is an enlarged sectional view of a main part of the heat exchange element group 3. As shown in the figure, an electric insulating film 33 is formed on the heat-absorbing heat exchange substrate 2, and a heat-absorbing electrode 34 is bonded thereon with or without a thin film 38. Further, the P-type semiconductor layer 35 and N
The mold semiconductor layer 36 is joined, and the heat radiation side electrode 37 is joined thereon.

On both sides of the heat radiation side electrode 37, there are provided semiconductor bonding regions 40, 40 for bonding to the P-type semiconductor layer 35 and the N-type semiconductor layer 36, and one of the electrodes 37 is provided between the regions 40, 40. One notch-shaped first notch 50a extending from the side edge 37a toward the other side edge 37b
Conversely, one cut-groove-shaped second extending from the other side edge 37b of the electrode 37 toward the one side edge 37a and formed at a position shifted from the first notch 50a is formed. Notches 50b are provided in parallel. A narrow conducting portion 51 is formed between the first notch portion 50a and the second notch portion 50b, and the planar shape of the heat absorbing side electrode 37 is substantially S
It is shaped like a letter.

The semiconductor junction regions 40, the notches 50 a, 50 b, and the conducting portion 51 are provided at symmetrical positions about the center O of the electrode 37. The electrode 37 has one side edge 37a to the other side edge 37b.
The width of the first notch 50a and the second
When the length of the notch portion 50b is L2, there is a relationship of L1 <L2, and the first notch portion 50a and the second notch portion 50b
Overlap near the center O.

As described above, the first notch 50a and the second notch 50b are provided so as to face each other with the positions slightly shifted between the regions 40, 40, thereby forming an S-shape.
The horizontal stress indicated by the arrow in the figure can be efficiently absorbed.

FIG. 5 is a diagram showing a second embodiment of the present invention. This embodiment is different from the first embodiment in that a bent portion 39 is formed on both sides of the electrode 37 in a Z-shape or U-shape (in this embodiment, a Z-shape). Is a point. With such a shape, both the vertical and horizontal stresses due to the repetition of the thermal cycle can be effectively absorbed, and damage to the thermoelectric conversion element group 3 can be avoided as much as possible.

In the above embodiment, the radiation side electrode 3
7, the first and second notches 50a and 50b are formed.
Similarly, the first and second cutouts 50a,
50b can also be formed.

In the above embodiment, the case of the electronic cooling device has been described, but the present invention is also applicable to a power generation device. 6 to 9 are views for explaining the third embodiment of the present invention. FIG. 6 is an exploded cross-sectional view of the power generator, FIG. 7 is a cross-sectional view of an element block used in the power generator, and FIG.
Is a sectional view of a barrier metal layer used for the element block, and FIG. 9 is a plan view of an electrode used for the power generation device.

In FIG. 6, reference numeral 60 denotes a high-temperature-side heat conductor made of copper, and an electric insulating layer 61 made of aluminum nitride is formed on the lower surface. Numeral 62 denotes a skeleton type skeleton type element block as shown in FIG. 7, which includes a high-temperature side electrode 63 made of a nickel-plated copper plate and a solder layer 64a.
And a barrier metal layer 65a formed with a surface treatment film of nickel or iron, a P-type semiconductor layer 66 and an N-type semiconductor layer 62 made of Pb-Te, and a barrier metal layer formed with a surface treatment film of nickel or iron. And a layer 65b. The members constituting the element block 62 are integrally sintered.

As shown in FIG. 8, the barrier metal layer 65 is provided with a peripheral wall projection 68 and a central projection 69 on the side in contact with the conductor layer 66 (67), thereby increasing the bonding strength with the conductor layer 66 (67). ing. The central projection 69 is not always necessary.

The barrier metal layer 65b and the low-temperature side electrode 70
Are joined by the solder layer 64b. 71 is a thin film made of silicone gel, 72 is a low-temperature side heat conductor made of aluminum, and an electric insulating layer 73 made of alumite is formed on the upper surface.
Are formed. Reference numeral 74 denotes a water-cooled bellows joined to the low-temperature side heat conductor via the thin film 71, and a cooling water 75 is circulated inside the bellows. In the case where the electrode 63 and the barrier metal layer 65a and the barrier metal layer 65b and the low-temperature side electrode 70 are bonded to each other, the solder layers 64a, 64
b is not always necessary.

As shown in FIG. 9, on both sides of the electrode 63 (70), there are provided semiconductor junction regions 76, 76 for joining with the P-type semiconductor layer 66 and the N-type semiconductor layer 67, respectively.
6, 76, one side edge 63 of the electrode 63 (70)
a (70a) toward the other side edge 63b (70b) from the one notch-shaped first notch 77a and the other side edge 63b (70b) of the electrode 63 (70). Extending toward one side edge 63a (70a), and
A notch-shaped second notch 77b formed at a position shifted from the notch 77a is provided in parallel.
A narrow conducting portion 78 is formed between the first notch 77a and the second notch 77b, and the electrode 63 (70)
Has a substantially S-shaped planar shape.

The semiconductor junction regions 76, 76, the notches 77a, 77b, and the energizing portion 78 are connected to the electrodes 63 (7
0) are provided at symmetrical positions with respect to the center O.

FIG. 10 is a diagram showing a fourth embodiment of the present invention. This embodiment is different from the above-described embodiment in that notches 77a are provided on both sides of a notch 77a.
b is formed. Also in this example, the semiconductor junction regions 76, 76, the cutout portions 77a, 77b, and the conducting portion 78 are provided at symmetrical positions about the center O of the electrode 63 (70).

9 and 10, L1 <L
2, the first notch 77a and the second notch 7
7b overlaps near the center O.

[0038]

FIG. 12 is a graph showing the relationship between the number of cycles and the rate of change in resistance of a thermoelectric converter according to an embodiment of the present invention and a conventional thermoelectric converter in a 40 ° C./90° C. temperature cycle acceleration test. In the characteristic diagram shown, a curve I in the figure is a characteristic curve of the thermoelectric converter according to the embodiment of the present invention, and a curve II is a characteristic curve of the conventional thermoelectric converter.

As is clear from this figure, in the conventional thermoelectric converter, the rate of change in resistance at the junction between the semiconductor layer and the electrode becomes extremely high with the repetition of the temperature cycle. On the other hand, the thermoelectric conversion device of the present invention effectively absorbs the difference in the coefficient of thermal expansion between the semiconductor layer and the electrode depending on the shape of the electrode, so that the resistance change rate is small and the performance is stable.

As described above, according to the present invention, the electrode has a semiconductor junction region near both ends, and between the semiconductor junction region,
A first notch extending from one side edge of the electrode toward the other side edge; and a first notch extending from the other side edge of the electrode toward one side edge and extending from the first notch. A second notch formed at a shifted position is provided, and the first notch and the second notch are provided.
Are formed between the notches.

Therefore, by effectively absorbing the difference in the thermal expansion coefficient between the semiconductor layer and the electrode and maintaining the bonding strength,
It is possible to provide a thermoelectric conversion device that has little performance deterioration even after repeated heat cycles, has excellent operation reliability, and has a long service life.

[Brief description of the drawings]

FIG. 1 is a sectional view of a thermoelectric conversion device according to a first embodiment of the present invention.

FIG. 2 is a bottom view of a first heat dissipation side frame used in the thermoelectric conversion device.

FIG. 3 is a partially enlarged cross-sectional view for describing a lead wire take-out structure in the thermoelectric conversion device.

FIG. 4 is a perspective view of a main part of an element block in the thermoelectric converter.

FIG. 5 is a perspective view of an electrode used in a thermoelectric converter according to a second embodiment of the present invention.

FIG. 6 is an exploded cross-sectional view of a thermoelectric conversion device according to a third embodiment of the present invention.

FIG. 7 is a sectional view of an element block of the thermoelectric converter.

FIG. 8 is a plan view of a barrier metal layer used for the element block.

FIG. 9 is a plan view of an electrode used in the thermoelectric conversion device.

FIG. 10 is a plan view of an electrode used in a thermoelectric conversion device according to a fourth embodiment of the present invention.

FIG. 11 is a sectional view of a conventional thermoelectric converter.

FIG. 12 is a characteristic diagram of a rate of change in resistance of the thermoelectric conversion device according to the embodiment of the present invention and a conventional thermoelectric conversion device with repetition of a temperature cycle.

[Explanation of symbols]

 REFERENCE SIGNS LIST 1 heat absorbing member 2 heat absorbing side heat exchange base 3 thermoelectric conversion element group 4 heat radiation side heat exchange base 34 heat absorbing side electrode 35 P-type semiconductor layer 36 N-type semiconductor layer 37 heat absorbing side electrode 37a one side edge 37b the other side edge Reference Signs List 40 semiconductor bonding region 50a first cutout portion 50b second cutout portion 51 conducting portion 60 high-temperature side heat conductor 62 element block 63 high-temperature side electrode 63a (70a) one side edge 63b (70b) the other side edge 66 P-type semiconductor layer 67 N-type semiconductor layer 70 Low-temperature side electrode 76 Semiconductor junction region 77a First cutout portion 77b Second cutout portion 78 Current-carrying portion O Center of electrode L1 Width of electrode L2 First and second cutout portions length

Claims (4)

[Claims] 1. A thermoelectric conversion device having a large number of semiconductor layers and a large number of electrodes for electrically connecting the semiconductor layers, wherein at least one of the semiconductor layers has a skeleton type. At least a part of them has a semiconductor junction region near both ends, and between the semiconductor junction regions,
A first notch extending from one side edge of the electrode toward the other side edge; and a first notch extending from the other side edge of the electrode toward one side edge and extending from the first notch. A thermoelectric conversion device comprising: a second notch formed at a shifted position; and a narrow current-carrying portion formed between the first notch and the second notch. 2. The thermoelectric conversion device according to claim 1, wherein the semiconductor junction region, the notch portion, and the current-carrying portion are provided at symmetrical positions from the center of the electrode. 3. The thermoelectric conversion device according to claim 1, wherein a plane shape of the electrode is substantially S-shaped by the semiconductor junction region, the cutout portion, and the conducting portion. 4. The electrode according to claim 1, wherein a width from one side edge to the other side edge of the electrode is L1, a length of the first cutout and a length of the second cutout. A thermoelectric conversion device, wherein L1 <L2, where L2 is the length.