JP2002203993A - Substrate for thermoelectric modules and thermoelectric module using the substrate - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a highly reliable substrate for thermoelectric modules and the thermoelectric module using the substrate wherein the cooling and temperature-rise characteristics of the module are improved, and its output is increased, and further, its thermal-cycle resistance is improved. SOLUTION: In the thermoelectric module, there are bonded to at least one side of a silicon nitride substrate 1 thirty or more metal plates 2 on each of which a thermoelectric element 3 is to be mounted.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a technology relating to a thermoelectric module for mutually converting heat energy and electric energy, and aims at improving cooling / heating characteristics, increasing output, and improving heat cycle characteristics. The present invention relates to a thermoelectric module substrate and a thermoelectric module using the same.

[0002]

2. Description of the Related Art A thermoelectric module utilizes the property of a thermoelectric element in which a p-type thermoelectric element and an n-type thermoelectric element are electrically connected in series, and converts heat energy into electric energy. Or an independent component having a function of converting electric energy into heat energy.

More specifically, the thermoelectric element has a Seebeck effect in which a potential difference is generated when a temperature difference is applied between a junction between a p-type thermoelectric element and an n-type thermoelectric element. Has a Peltier effect of absorbing or generating heat according to the direction of the current when electric current flows between the junctions, and the electric energy and the heat energy are mutually converted using such an effect. For this reason, the thermoelectric module is mounted on various devices such as a thermoelectric power generation device that generates electric power using waste heat, a constant temperature device in a semiconductor process, and a thermoelectric cooling device that cools an electronic device. I have.

The thermoelectric module has a configuration in which an electrode plate (metal plate) is joined to at least one surface of the insulating substrate with the insulating substrate as a base, and a thermoelectric element is connected to the electrode plate.

[0005] As described above, the thermoelectric element is formed by connecting a p-type thermoelectric element and an n-type thermoelectric element one by one in series, and this is the minimum unit. Then, the cooling / heating characteristic or the voltage characteristic of the thermoelectric module is determined according to the number of thermoelectric elements mounted as the minimum unit. Therefore, it is necessary to mount a plurality of thermoelectric elements on the insulating substrate in order to improve the cooling / heating characteristics of the thermoelectric module or to increase the output, and accordingly, the insulating substrate on which the thermoelectric elements are mounted must be mounted. It was essential to increase the area of the substrate.

Heretofore, as such an insulating substrate, a ceramic sintered body capable of securing relatively excellent thermal conductivity and mechanical strength has been applied. For example, alumina (Al ₂₎
O ₃ ) sintered body, aluminum nitride (AlN) sintered body, barelya (BeO) sintered body, cordierite (2MgO)
A ceramic sintered body such as an (Al ₂ O ₃ .SiO ₂ ) sintered body has been applied.

[0007]

However, in the above-mentioned ceramic substrate, it is difficult to increase the area of the ceramic substrate since sufficient element strength cannot be obtained. As a result, mounting of the thermoelectric module is difficult. The number is limited, and it has been difficult to improve the cooling / heating characteristics and increase the output of the thermoelectric module required in recent years. In fact,
The size of the ceramic substrate surface on which the thermoelectric element is mounted is 5 cm
The angle was the upper limit, and the number of thermoelectric elements that could be mounted was limited.

As described above, the conventional ceramic sintered body is
Since the strength characteristics are not satisfied, attempts have been made to increase the substrate strength as a thick ceramic substrate exceeding 1 mm and increase the substrate area of the ceramic substrate. However, when a thermoelectric module is configured using a thick ceramic substrate, there is a problem that the thermoelectric module itself becomes large.

Further, the thermoelectric module is used under conditions where the thermal cycle conditions are more severe than those of ordinary semiconductor devices because a large number of thermoelectric devices are provided on a substrate. For this reason, if the substrate area of the ceramic substrate is increased and a plurality of metal plates are joined on the ceramic substrate, cracks occur due to the difference in thermal expansion between the ceramic substrate and the metal plate. By repeating the cooling / heating cycle of the thermoelectric module, the metal plate eventually peels off, resulting in a problem that the reliability of the thermoelectric module is reduced.

In particular, when a plurality of metal plates are arranged on a ceramic substrate, if the distance between adjacent metal plates is set to be less than 1 mm, the influence of the difference in thermal expansion between the metal plate and the ceramic substrate becomes remarkable, There was a problem that the cycle characteristics deteriorated.

SUMMARY OF THE INVENTION The present invention has been made to solve the above-mentioned problems, and has been made to improve the cooling / heating characteristics and to increase the output, and to provide a thermoelectric device having high reliability in which the heat cycle characteristics have been improved. It is an object to provide a module substrate and a thermoelectric module using the same.

[0012]

As a result of various studies to solve the above-mentioned problems, the present inventor has found that a ceramic substrate is formed from a silicon nitride sintered body having a high element bending strength, so that the surface of the silicon nitride substrate can be reduced. The size of the thermoelectric module can be increased to 5 cm square or more. By joining multiple metal plates on a silicon nitride substrate and increasing the number of thermoelectric elements to be mounted, the cooling / heating characteristics of the thermoelectric module can be increased. And improved output. In addition, since the silicon nitride sintered body is a material having a lower coefficient of thermal expansion than the conventional ceramic sintered body, even when the thermoelectric module is repeatedly subjected to a cooling / heating cycle, the metal plate and the ceramic are not removed. The inventors have found that a decrease in heat cycle characteristics due to a difference in thermal expansion with the substrate can be prevented and the heat cycle characteristics can be significantly improved, and the present invention has been completed.

A thermoelectric module substrate according to the present invention is characterized in that a metal plate for mounting 30 or more thermoelectric elements is bonded to at least one surface of a silicon nitride substrate.

As in the present invention, the number of thermoelectric elements that can be mounted is increased by joining 30 or more metal plates to at least one surface of the silicon nitride substrate, whereby the cooling / heating of the thermoelectric module is increased. The characteristics can be improved and the output can be increased.

In the thermoelectric module, it is desirable that the distance between the metal plates is 1 mm or less. Even in the case where the distance between the metal plates is set to 1 mm or less in this way, in the present invention, since the silicon nitride sintered body having excellent heat radiation characteristics is used as the substrate, the thermal expansion Separation of the silicon nitride substrate and the metal plate due to the difference can be prevented, and as a result, deterioration of the heat cycle characteristics of the thermoelectric module can be prevented. In addition,
When the distance between the metal plate and the metal plate is less than 0.3 mm, the heat cycle characteristics are deteriorated.
It is good to set it in the range of m or more and 1 mm or less.

In the thermoelectric module, the area of the metal plate (for example, when the metal plate is rectangular, the product of length and width) is desirably 25 mm ² or less. By reducing the area of the metal plate to 25 mm ² or less as described above, the bonding area between the silicon nitride substrate and the metal plate is reduced, thereby preventing the silicon nitride substrate and the metal plate from peeling off, and performing a heat-resistant cycle. A thermoelectric module with improved characteristics can be obtained.

In the above thermoelectric module, the surface area of the surface of the silicon nitride substrate to be joined to the metal plate is 1600.
mm ² or more (for example, when the silicon nitride substrate is rectangular, it is determined by the product of length and width). Increasing the size of the silicon nitride substrate in this way increases the number of metal plates bonded on the silicon nitride substrate, thereby increasing the number of thermoelectric elements mounted, and as a result, the cooling / heating characteristics of the thermoelectric module. Improvement and higher output can be achieved.

In the above thermoelectric module, the silicon nitride substrate preferably has a thickness of 0.2 to 1.0 mm. The reason for this is that if the plate thickness exceeds 1.0 mm, the thermal resistance value increases and the heat dissipation decreases, and as a result, the heat cycle characteristics deteriorate. On the other hand, if the plate thickness is less than 0.2 mm, The reason is that the silicon nitride substrate becomes too thin, so that the durability is lowered and the mechanical strength cannot be obtained, and in any case, the reliability of the thermoelectric module is lowered.

In such a thermoelectric module, the silicon nitride substrate preferably has a thermal conductivity of 65 W / m · K or more. The reason for this is that if the thermal conductivity of the silicon nitride substrate is less than 65 W / m · K, the thermal resistance of the silicon nitride substrate will increase, and the heat resistance cycle characteristics will decrease. Further, it is desirable that the thermal conductivity of the silicon nitride substrate is 85 W / mK or more. As a silicon nitride sintered body having such high thermal conductivity,
For example, a material in which a grain boundary phase in a silicon nitride sintered body is crystallized by 20% or more with respect to all grain boundary phases can be mentioned. In order to crystallize the grain boundary phase, it is effective to cool the furnace at a rate of 100 ° C./h or less after sintering. Similarly, Al,
Controlling the total amount of impurity cations of Li, Na, K, Fe, Mn, and B to 0.2% by mass or less is also effective in improving the thermal conductivity. The substrate for a thermoelectric module of the present invention is characterized by using a silicon nitride sintered body, and is not limited to such a silicon nitride sintered body.

In the thermoelectric module, the silicon nitride substrate preferably has a three-point bending strength of 600 MPa or more. By increasing the mechanical strength by setting the three-point bending strength of the silicon nitride substrate to 600 MPa or more, a thermoelectric module having high reliability can be obtained.

In the above thermoelectric module, the metal plate is
It is desirable that at least one material selected from copper or aluminum be the main component.

Further, in the thermoelectric module, it is preferable that the surface of the metal plate is plated with Ni.

In the above thermoelectric module, T
It is desirable that a metal plate be joined to the silicon nitride substrate via a brazing material layer containing at least one active metal selected from i, Zr, Hf, Al and Nb. Thus, by joining the metal plate on the silicon nitride substrate via the brazing material layer containing the active metal, the two can be firmly joined.

[0024]

DESCRIPTION OF THE PREFERRED EMBODIMENTS A thermoelectric module according to the present invention will be described below with reference to FIGS. 1 and 2 and Tables 1 to 3.

First Embodiment (Table 1, FIG. 1 and FIG. 2) Examples 1 and 2 and Reference Examples 1 and 2 In this embodiment, a metal plate is bonded on a Si ₃ N ₄ substrate.
A thermoelectric module in which a thermoelectric element was connected to this metal plate was produced, and the output and the cooling / heating characteristics of the thermoelectric module were tested to evaluate the performance.

First, 1.3% by mass of oxygen and 0.10% by mass in total of Al, Li, Na, K, Fe, Mn, and B as impurity cation elements are contained, and α-phase Si ₃ N _{4 is} contained. 97
% Of Si ₃ N ₄ raw material powder having an average particle size of 0.40 μm and Y ₂ O _{3 having} an average particle size of 0.7 μm as a sintering aid.
5% by mass of powder, 1.5 of MgO powder having an average particle size of 0.5 μm
% By mass, wet-mixed in ethyl alcohol for 72 hours, and dried to prepare a raw material powder mixture.

Next, a predetermined amount of an organic binder was added to the raw material powder mixture, mixed uniformly, and then press-molded at a molding pressure of 120 MPa to obtain a molded body.

After the molded body was degreased in a stream of air at 500 ° C. for 2 hours, the degreased body was placed in a nitrogen gas atmosphere.
After maintaining at 1800 ° C. for 8 hours under 5 atm and performing densification sintering, the amount of electricity supplied to a heating device attached to the sintering furnace is controlled until the temperature in the sintering furnace drops to 1500 ° C. In the meantime, the cooling was performed at a cooling rate of 100 ° C./h or less, and the Si ₃ N ₄ sintered body having a crystallization ratio of the grain boundary phase of 20% or more (thermal conductivity 8
8 W / m · K, three-point bending strength 700 MPa) 55 mm long, 55 mm wide, 0.635 mm thick S
An i ₃ N ₄ substrate was used.

On the Si ₃ N ₄ substrate, Ag: C
u: In: Ti = 61.9: 24.1: 10: 4 active metal brazing paste is screen-printed, and a 3 mm long, 5 mm wide, 0.3 mm thick Cu plate is placed on the dried paste. Is set to 0.6 mm, and the distance between each Cu plate is set to 0.6 mm.
And six on each side, for a total of 42 on a Si ₃ N ₄ substrate. Thereafter, bonding was performed at 800 ° C. for 10 minutes in a vacuum of 1 × 10 ⁻⁴ Torr or less to obtain a Si ₃ N ₄ substrate for a thermoelectric module.

Further, this thermoelectric module Si ₃ N ₄
A thermoelectric module was formed by connecting a thermoelectric element in which one p-type thermoelectric element and one n-type thermoelectric element were connected to a Cu plate as a substrate. This thermoelectric module was used as an example. FIG. 1 is a view of the thermoelectric module as viewed from above, and FIG.
FIG. 2 shows a cross-sectional view taken along the line A ′. Note that, as shown in FIG.
₃ N ₄ Example 1 that provided the thermoelectric elements through a Cu plate only one surface of the substrate, those having a thermoelectric element via the Cu plate symmetrically on both sides the Si ₃ N ₄ substrate as in FIG. 3 This is referred to as Example 2.

As shown in FIGS. 1 to 3, Si ₃ N
_{4 A} Cu plate 2 is bonded on a substrate 1, and
The thermoelectric element 3 is connected to the u-plate 2.

Further, similarly to the above-described embodiment, the height is 55 m.
m, horizontal 55 mm, to prepare a _Si 3 _{N 4} substrate having a thickness of 0.635 mm, a mass ratio to the _Si 3 _{N 4} substrate Ag: C
u: In: Ti = 61.9: 24.1: 10: 4 active metal brazing paste is screen-printed, and a 3 mm long, 5 mm wide, 0.3 mm thick Cu plate is placed on the dried paste. The length of each Cu plate is 2 mm, 4
5 sheets are arranged side by side, and a total of 20 sheets are placed on the Si ₃ N ₄ substrate.
Were placed. Thereafter, bonding was performed at 800 ° C. for 10 minutes in a vacuum of 1 × 10 ⁻⁴ Torr or less to obtain a Si ₃ N ₄ substrate for a thermoelectric module. Then, a power generation element was connected in the same manner as in the above-described embodiment to form a power generation module. In addition, the case where the thermoelectric element was provided on only one side via the Cu plate was referred to as Reference Example 1, and the case where the thermoelectric element was provided on both sides via the Cu plate was referred to as Reference Example 2.

When the output and the cooling / heating characteristics of the power generating elements of the thermoelectric modules of the above embodiment and the reference example were examined, the examples 1 and 2 in which a large number of thermoelectric elements were mounted were compared with the reference examples 1 and 2. The characteristics were superior to those of Reference Example 2.

Next, the thermoelectric element module substrates of Examples 1 and 2 and Reference Examples 1 and 2 were subjected to heat cycle property evaluation (TCT test). The heat cycle test was performed at -40 ° C x 30 min → R. T. (Room temperature) x 10m
in → 125 ° C. × 30 min → R. T. (Room temperature) x 10
A TCT test with 1 cycle of min was performed, and 200
The presence or absence of cracks after the cycle was evaluated as a soundness index η. 100% of the soundness index η is “TC
No cracks occurred after T test ", 0% was" TC
After the T test, cracks were generated over the entire surface. " For the measurement of the soundness index η, the Cu plate and the active metal brazing material layer of the thermoelectric module substrate after the TCT test were removed by etching, and each Si ₃ N ₄ substrate was subjected to a fluorescent flaw detection test (PT) to check for cracks. Was measured. The soundness index η was calculated according to the following mathematical formula.

[0035]

## EQU1 ## where D is the path of the edge of the Cu plate where cracks may occur in the longitudinal direction of the joint of the thermoelectric module substrate in the longitudinal direction. the total length, [Sigma] d is the length of each crack generated on the path _{(d 1, d 2, d} 3, ... d n) shows the sum of. Table 1 shows the results.

[0036]

[Table 1]

As shown in Table 1, the thermoelectric module substrate according to the present embodiment can be used regardless of whether the number of Cu plates is 30 or more on one surface or whether it is provided on both surfaces. No crack was observed. This shows that the number of Cu plates is small as in Reference Examples 1 and 2, and the same characteristics as those in which the Cu plates are spaced are used, and a silicon nitride sintered body is used as a thermoelectric module substrate. This indicates that it is possible to connect a large number of metal plates with a reduced interval.

Therefore, according to the present embodiment, Si₃N₄
Larger Si formed from sintered body ₃N₄Make substrate
And this Si₃N₄Join 30 or more metal plates on a substrate
By increasing the number of thermoelectric elements installed,
High output and excellent cooling / heating characteristics
You.

Second Embodiment (Tables 2 and 3) In this embodiment, various ceramic substrates for thermoelectric modules for mounting thermoelectric elements were manufactured, and the three-point bending strength characteristics and The heat cycle characteristics were evaluated.

Examples 3 to 8 (Table 2) First, according to the manufacturing method shown in the first embodiment, Si ₃ having the substrate surface size, plate thickness, and thermal conductivity shown in Table 2 below is used.
A Si ₃ N ₄ substrate formed from an N ₄ sintered body was manufactured.
This was designated as Example 3 to Example 8. In each of Examples 3 to 8, the metal plate was bonded to only one surface of the Si ₃ N ₄ substrate.

Next, the Si ₃ N shown in Examples 3 to 8 was used.
_A Cu plate was bonded to the _four substrates by an active metal bonding method to obtain a Si ₃ N ₄ substrate for a thermoelectric module. Note that the manufacturing method of the active metal bonding method was the same as the manufacturing method described in the first embodiment.

Specifically, six Cu plates each having a length of 3 mm, a width of 5 mm, and a thickness of 0.3 mm are arranged vertically and five horizontally, and a total of 30 Cu plates are arranged on a Si ₃ N ₄ substrate. This was designated as Example 3. In addition, 3 mm long, 5 mm wide, and 0.
Cu plates having a thickness of 3 mm are arranged vertically 10 and horizontally 10 with the interval between the Cu plates being 0.6 mm, and Si ₃ N ₄
Fourth and fifth examples were a total of 100 pieces arranged on the substrate.

Further, in Examples 6 to 8, the direct bonding method was used to
i ₃ N ₄ was prepared substrate.

In Example 6, a Si ₃ N ₄ substrate having the size, thickness, and thermal conductivity of the substrate surface shown in Table 2 was used.
₃ N ₄ thick silicon oxide 1~3μm on the substrate _(SiO 2)
A film was formed. After that, the height is 3 mm, the width is 5 mm, and the thickness is 0.
Six 3 mm Cu plates are arranged vertically and five horizontally.
A total of 30 pieces were arranged on the Si ₃ N ₄ substrate. And
Bonding was performed by heating at 1070 to 1075 ° C. for 10 to 20 minutes to form a Si ₃ N ₄ substrate for a thermoelectric module. In addition, the thing which used the Cu board as the Al board was Example 7.

In Example 8, the size, thickness and thermal conductivity of the substrate surface shown in Table 2 were 3 m long on a Si ₃ N ₄ substrate.
10 mm long, 5 mm wide, 0.3 mm thick Cu plate
Like, next to Put each 10 sheets, _Si 3 _{N 4} in total and 100 disposed on the substrate to form a _Si 3 _{N 4} substrate thermoelectric module in the same manner as in Example 4.

[0046]

[Table 2]

Comparative Examples 1 to 10 In this comparative example, the thermal conductivity of the ceramic substrate was 20 W.
/ M · K applied Al ₂ O ₃ sintered body (Comparative Example 1) and thermal conductivity of 170 W / m · K AlN sintered body applied (Comparative Examples 2 to 4) ), Si ₃ N ₄
A substrate having a different substrate area (Comparative Examples 5 and 6);
A substrate in which the thickness of the Si ₃ N ₄ substrate is changed (Comparative Examples 7 and 8), a substrate in which a Si ₃ N ₄ sintered body having a thermal conductivity of 60 W / m · K is applied (Comparative Example 9), A metal plate was made of Co using a Si ₃ N ₄ sintered body (Comparative Example 10), and a Si ₃ N ₄ substrate for a thermoelectric module was formed.

The above Examples 3 to 8 and Comparative Examples 1 to
Si for thermoelectric module of Comparative Example 10 ₃N₄Using a substrate
Evaluation tests for 3-point bending strength and heat cycle characteristics
went.

The three-point bending strength was measured by a three-point bending strength according to JIS-R-1601. Further, the heat cycle characteristics were measured by the same method as in Example 1. Table 2 shows the results.

As shown in Table 2, all of the silicon nitride substrates for thermoelectric modules shown in Examples 3 to 8 had a three-point bending strength as high as 600 MPa or more and a soundness index η of 10 or more.
It was 0%, and both the strength characteristics and the heat cycle characteristics were good. On the other hand, Comparative Examples 1 to 4,
In Comparative Examples 7 to 10, any one of the three-point bending strength and the heat cycle characteristic was deteriorated. In Comparative Examples 5 and 6, the three-point bending strength and the heat cycle resistance were excellent, but the number of metal plates that could be joined was small due to the small substrate area. The cooling characteristics could not be improved. Incidentally, _Si 3 _{N 4} substrate shown in Example 3 to Example 8, the thermal conductivity as high as 65W / m · K or more, since the three-point bending strength can be increased and more 600 MPa, Si ₃
The thickness of the N ₄ substrate by thin form, can be made compact thermoelectric module. Furthermore, Si
The ₃ N ₄ substrate by a thin, to reduce the thermal resistance,
As a result, it is possible to increase the output of the thermoelectric module and improve the cooling / heating characteristics.

Embodiments 9 to 17 In this embodiment, the above-described Embodiments 3, 5, and 6 are described.
Using the same manufacturing method as described above, the Si ₃ N ₄ substrates for thermoelectric modules of Examples 9 to 17 were produced.

In Examples 9 to 17, as shown in Table 3, the surface area of the bonding surface of each Cu plate to the substrate was 25 mm.
^{When the} Cu plate is bonded to the surface of the Si ₃ N ₄ substrate by 30 or more, and the Cu plate is bonded to the surface of the Si ₃ N ₄ substrate, the Cu plate and the Cu plate Is 1 mm or less.

[0053]

[Table 3]

Comparative Examples 11 to 15 In this comparative example, Si ₃ N ₄ for the thermoelectric module of Comparative Examples 11 to 15 was manufactured using the same manufacturing method as in Examples 3, 5 and 6. A substrate was prepared.

In Comparative Examples 11 to 13, the substrate surface area of the Cu plate was set to 25 mm ² or more. In Comparative Examples 14 and 15, the distance between the Cu plates was set to 0.2 mm. Cu plate was joined to _Si 3 _{N 4} substrate to form a _Si 3 _{N 4} thermoelectric module substrate.

Using the Si ₃ N ₄ substrates for thermoelectric modules of Examples 9 to 117 and Comparative Examples 11 to 15, heat cycle resistance was evaluated. The test conditions were the same as the conditions for the above-described evaluation test of the heat cycle characteristics. Table 3 shows the results.

As shown in Table 3, the Si ₃ N ₄ substrates for thermoelectric modules of Examples 9 to 17 in which the surface area of the bonding surface of each Cu plate to the substrate was 25 mm ² or less had a soundness index η. Each showed 100%, indicating that the heat cycle characteristics were good. On the other hand, Si ₃ N ₄ for thermoelectric modules of Comparative Examples 11 to 13 using Cu plates having a surface area of the bonding surface of each Cu plate to the substrate exceeding 25 mm ^2.
In the substrate, the soundness index η was reduced due to the separation between the Si ₃ N ₄ substrate and the Cu plate after the thermal cycle of cooling / heating, and the heat cycle characteristics were reduced. Further, the Si ₃ N ₄ substrates for thermoelectric modules of Comparative Examples 14 and 15 in which the distance between the Cu plates was narrowed were the Cu plates and the Si ₃ N ₄
Since the influence of the difference in thermal expansion from the substrate was remarkable, the soundness index η was low, and the heat cycle characteristics were low.

Therefore, according to the present embodiment, the substrate surface area of the metal plate is set to 25 mm ₂ or less to prevent separation between the ceramic substrate and the metal plate, thereby improving the heat resistance cycle characteristics, and improving the space between the metal plates. By defining and arranging the above, both the three-point bending strength characteristics and the heat resistance cycle characteristics can be improved. Thereby, a highly reliable thermoelectric module can be obtained.

Further, silicon nitride sintered body having a high element bending strength
By applying the body,₃N ₄Set the board thickness to 0.
Since it can be made as thin as 32 mm,
Module and make the board thinner
To reduce the thermal resistance of the ceramic substrate.
Cooling and heating characteristics of the thermoelectric module
It is possible to improve the performance and increase the output.

[0060]

As described in the foregoing, according to the thermoelectric module substrate of the present invention, the Si ₃ N ₄ substrate is large, the metal plates to be bonded to the Si ₃ N ₄ substrate is 30 or more,
By increasing the number of mounted power generating elements, it is possible to increase the output of the thermoelectric module or to improve the cooling / heating characteristics, and to improve the heat cycle characteristics, thereby improving the reliability of the thermoelectric module.

[Brief description of the drawings]

FIG. 1 is a diagram illustrating an embodiment of the present invention, and is a top view of a thermoelectric module as viewed from above.

FIG. 2 is a cross-sectional view of the thermoelectric module according to the embodiment of the present invention.

FIG. 3 is a cross-sectional view of the thermoelectric module according to the embodiment of the present invention.

[Explanation of symbols]

 Reference Signs List 1 silicon nitride substrate 2 metal plate (Cu plate) 3 thermoelectric element

Claims (11)

[Claims] 1. A thermoelectric module substrate, wherein a metal plate for mounting at least 30 thermoelectric elements is bonded to at least one surface of the silicon nitride substrate. 2. The thermoelectric module substrate according to claim 1, wherein a distance between the metal plates is 1 mm or less. 3. The thermoelectric module substrate according to claim 1, wherein a surface area of a bonding surface of the metal plate to the substrate is 2 or more.
A thermoelectric module substrate having a size of 5 mm ² or less. 4. The thermoelectric module substrate according to claim 1, wherein a surface area of a surface of the silicon nitride substrate to be bonded to the metal plate is 1600 mm ² or more. substrate. 5. The thermoelectric module substrate according to claim 1, wherein the silicon nitride substrate has a thickness of 0.2 to 1.0 mm. 6. The thermoelectric module substrate according to claim 1, wherein the thermal conductivity of the silicon nitride substrate is 65 W / m · K or more. 7. The thermoelectric module substrate according to claim 1, wherein the silicon nitride substrate has a three-point bending strength of 600 MPa or more. 8. The thermoelectric module substrate according to claim 1, wherein the metal plate contains at least one material selected from copper and aluminum as a main component. Module substrate. 9. The thermoelectric module substrate according to claim 1, wherein the surface of the metal plate is Ni-plated. 10. The thermoelectric module substrate according to claim 1, wherein Ti, Zr, Hf,
A thermoelectric module substrate, wherein a metal plate is joined to the silicon nitride substrate via a brazing material layer containing at least one active metal selected from Al and Nb. 11. A thermoelectric module using the thermoelectric module substrate according to any one of claims 1 to 10.