JP2001007411A - Thermoelectric module - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To improve reliability without lowering cooling efficiency. A thermoelectric element module in which a plurality of thermoelectric elements are electrically connected in series by a plurality of electrodes by connecting adjacent thermoelectric elements with electrodes. A side surface of each thermoelectric element 1 is covered with a coating layer 3 made of an organic resin, and a coating layer 3 of an adjacent thermoelectric element 1
Provide a space between them. The thermoelectric element 1 which is a brittle material is reinforced by covering it with the covering layer 3, and a space is provided between the covering layers of the adjacent thermoelectric elements to suppress heat conduction through the covering layer 3.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelectric element module in which p-type and n-type thermoelectric elements are electrically connected.

[0002]

2. Description of the Related Art In order to connect a p-type and an n-type thermoelectric elements sequentially with metal electrodes, a thermoelectric element module forms a π-type series circuit and terminates the series arrangement so that it can be electrically connected to the outside. In general, a ceramic substrate is provided outside the electrodes for maintaining the structure of the module and transporting heat to the outside.

However, in the module having this structure, the thermoelectric element is fragile and the coefficient of linear expansion between the thermoelectric element and the ceramic substrate is different, so that the element may be broken by thermal stress applied to the element during use. Many had reliability issues.

[0004] For this reason, there is a thermoelectric element module without a ceramic substrate. In this case, the fact that the thermoelectric element modules are arranged in series in a π-type structure means that
There is a problem in that the module itself has a bellows structure and handling is difficult.

[0005] Here, Japanese Patent Application Laid-Open No. 10-51039 proposes a technique in which a resin is filled between thermoelectric elements to enhance the thermoelectric elements and to give flexibility to the module. .

[0006]

However, in the above-mentioned publication in which the entire module is fixed with resin,
Since heat is transferred from the heat radiation side to the cooling side through the resin, heat leakage is large, and the cooling efficiency of the module is reduced.

SUMMARY OF THE INVENTION The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a thermoelectric element module capable of improving reliability without lowering cooling efficiency.

[0008]

SUMMARY OF THE INVENTION Accordingly, the present invention provides a thermoelectric element module in which a plurality of thermoelectric elements are electrically connected in series by a plurality of electrodes by connecting adjacent thermoelectric elements with electrodes. It is characterized in that the side surfaces of each thermoelectric element are covered with a coating layer made of an organic resin, and a space is provided between the coating layers of adjacent thermoelectric elements.

The thermoelectric element, which is a brittle material, is covered with a coating layer to reinforce the element. By providing a space between the coating layers of adjacent thermoelectric elements, heat conduction through the coating layer can be suppressed. It is like that.

As the thermoelectric element, a columnar element can be suitably used.

In addition, the coating layers of two adjacent thermoelectric elements may be coupled on the opposite side to the electrode electrically connecting the two thermoelectric elements, may be coupled on one end of the thermoelectric element, or may be further coupled. The thermoelectric element may be connected at the center.

It is also preferable to provide a polyimide layer between the thermoelectric element and the covering layer.

[0013] The coating layer may be formed of a bubble-containing resin.

An electrode having a junction with the thermoelectric element whose thickness is larger than the thickness of the bridge connecting the two junctions can be suitably used, and a thermoelectric element made of solder containing fine metal balls is preferably used. It is preferable to bond to the element.

The electrode may be one whose surface is covered with an insulating organic film, or the joint between the electrode and the thermoelectric element may be covered with a resin.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to an embodiment. As shown in FIG. 1, an n-type thermoelectric element 1 and a p-type thermoelectric element 1 are alternately formed by electrodes By connecting and having a π-type arrangement, these thermoelectric elements 1 are connected in series, and the lead wire 28 for external connection is led out from the terminal end. The side surfaces of the thermoelectric element 1 whose both ends are joined to the electrodes 2 and 2 are covered with a coating layer 3 made of polyimide resin or epoxy resin having a thickness of 5 to 20 μm. The thermoelectric element module shown in the figure is of a type without a ceramic substrate (skeleton type), but has a ceramic substrate 4 on one side or a ceramic substrate 4 on both sides. Is also good.

In any case, since the thermoelectric element 1 which is a brittle material is covered with the coating layer 3 to reinforce the thermoelectric element 1, cracks may occur in the thermoelectric element 1 due to thermal stress. Can be reduced. In addition, the coating layer 3
Is thin and has a space between the thermoelectric element 1 and the adjacent thermoelectric element 1, and there is almost no heat conduction through the coating layer 3, so that there is no decrease in thermoelectric conversion efficiency due to heat leakage.

At this time, as shown in FIG. 2, if the outer peripheral surface of the thermoelectric element 1 is covered with the coating layer 3 by using a cylindrical thermoelectric element 1, the thermoelectric element 1 has a square cross section. Since the stress concentration portion in the thermoelectric element 1 itself is dispersed as compared with the case where the thermoelectric element 1 is used, the reliability as the thermoelectric element module is further increased.

In order to improve the handling of the thermoelectric element module, a bridge 30 for connecting the coating layers 3, 3 of the adjacent thermoelectric elements 1, 1 may be provided.
The bridge 30 is formed of the same resin as the resin forming the coating layer 3.
A 1000 μm epoxy resin can be suitably used. At this time, as shown in FIG.
If the bridge 30 is provided on the side opposite to the electrode 2 electrically connecting the two, the structural part S shown by a square frame in FIG. Due to the module structure, the handleability is improved even in a type having no ceramic substrate.

As shown in FIG. 4, all the bridges 30 may be formed on one electrode 2 side. In this case, the structure S
Is smaller than that described above, so that the handleability can be improved while securing flexibility. Moreover, the reliability against the thermal stress of the thermoelectric element module increases due to the flexibility.

The bridge 30 may be provided at the center of the thermoelectric element 1 as shown in FIG. Bridge 30 serving as a partition plate for separating the space on one end side and the space on the other end side of thermoelectric element 1
In addition to ensuring the handleability of the module, it also improves the performance of the thermoelectric element module because it prevents heat transport by thermal convection.

When the coating layer 3 is formed of an epoxy resin, as shown in FIG.
After coating the inner layer 31 made of the polyimide resin, the coating layer 3 is preferably provided with a thickness of 5 to 1000 μm. Inner layer 31
The adhesive force between the coating layer 3 made of epoxy resin and the thermoelectric element 1 is improved due to the presence of, and the reinforcing effect of the thermoelectric element 1 by the coating layer 3 is improved.

As shown in FIG. 7, the coating layer 3 may be formed of a resin containing bubbles 33. For example, diameter 1-1
Epoxy resin containing bubbles of 00 μm and thickness of 5-10
The coating layer 3 having a thickness of 00 μm is formed. Due to the presence of the bubbles 33, the coating layer 3 has a low thermal conductivity,
Since the heat transport due to the coating layer 3 can be reduced, the performance of the thermoelectric element module can be improved. 6 and 7 show a skeleton type, in which a ceramic substrate 4 is arranged on one side,
Needless to say, ceramic substrates 4 and 4 may be provided on both sides.

In the case where the ceramic substrate 4 is disposed on at least one side, there is a problem of thermal stress due to a difference in linear expansion between the ceramic substrate 4 and the thermoelectric element 1, but this is a problem as shown in FIG. 2 can be eased by making the thickness of the joint 20 with the thermoelectric element 1 larger than the thickness of the bridge 21 connecting the two joints 20. For example, if the thickness of the bridge portion 21 is 0.2
When it is ~ 2 mm, the thickness of the joint 20 is 0.5-3 m
m. By utilizing the elasticity of the metal electrode 2, the thermal stress caused by the difference in linear expansion between the ceramic substrate 4 and the thermoelectric element 1 is reduced.

The thermal stress is applied to the electrode 2 as shown in FIG.
The diameter of the solder 5 for joining the thermoelectric element 1 to
It can also be relaxed by using a copper ball 50 having a thickness of about 1 mm. The solder 5 including a large number of fine balls 50 has a thickness (0.1
mm or more).

The surface of the electrode 2 is preferably covered with an insulating organic film 24. For example, if the insulating organic film 24 having a thickness of 5 to 25 μm is formed by vapor deposition of parylene or polyimide on a portion of the electrode 2 other than the joint surface with the thermoelectric element 1, the thermoelectric element module is combined with a heat sink or a cooling plate. As a result, the insulation reliability between the electrodes 2 is improved. The insulating organic film 24
Can be applied to all of the above-described examples in which the ceramic substrate 4 is not provided.

FIG. 11 shows a state where the joint between the electrode 2 and the thermoelectric element 1 by solder is covered with an epoxy resin 6. This resin 6 reinforces the joint between the electrode 2 and the thermoelectric element 1 and also causes the electrode 2 to contract with the joint due to shrinkage stress.
In order to constantly apply a compressive force in the direction of increasing the contact pressure between the thermoelectric element 1 and the thermoelectric element 1, the reliability of the joint is increased.

[0028]

As described above, in the present invention, a thermoelectric element module in which a plurality of thermoelectric elements are electrically connected in series by a plurality of electrodes by connecting adjacent thermoelectric elements with electrodes. The side surfaces of each thermoelectric element are covered with a coating layer made of an organic resin, and a space is provided between the coating layers of adjacent thermoelectric elements, so that the thermoelectric element, which is a brittle material, is reinforced by coating with a coating layer. This means that breakage due to thermal stress is unlikely to occur, and since a space is provided between the coating layers of adjacent thermoelectric elements, heat conduction through the coating layer can be suppressed,
The presence of the coating layer does not cause a decrease in thermoelectric conversion efficiency.

If a columnar thermoelectric element is used, the concentration of stress in the thermoelectric element itself can be dispersed, so that the risk of breakage of the thermoelectric element is further reduced.

In addition, when the coating layers of two adjacent thermoelectric elements are connected to each other on the side opposite to the electrode electrically connecting the two thermoelectric elements, high handling properties can be obtained even in a skeleton type. Can be obtained.

Further, if the covering layers of two adjacent thermoelectric elements are connected to each other at one end of the thermoelectric element, the handling property can be improved while securing flexibility.
Furthermore, if the coating layers of two adjacent thermoelectric elements are connected to each other at the center of the thermoelectric element, it is possible to obtain not only an improvement in handling properties but also an improvement in performance due to suppression of thermal convection.

It is also preferable to provide a polyimide layer between the thermoelectric element and the covering layer. By increasing the adhesion between the coating layer and the thermoelectric element, the effect of reinforcing the thermoelectric element can be improved.

If the coating layer is formed of a bubble-containing resin,
Since the thermal conductivity of the coating layer can be reduced, the heat conduction due to the coating layer can be further suppressed.

If an electrode having a thickness of a junction with the thermoelectric element is larger than a thickness of a bridge connecting the two junctions, an electrode having a ceramic substrate can be used.
The thermal stress applied to the thermoelectric element can be reduced. Further, even if the thermoelectric element is joined to the thermoelectric element with solder containing fine metal balls, the thermal stress applied to the thermoelectric element can also be reduced, and the thermoelectric element can be prevented from being broken.

If the surface of the electrode is covered with an insulating organic film, the insulation reliability in unitization is improved.

Further, if the joint between the electrode and the thermoelectric element is covered with a resin, the reliability of the joint between the electrode and the thermoelectric element can be improved.

[Brief description of the drawings]

FIG. 1 shows an example of an embodiment of the present invention, in which (a)
Is a perspective view, and (b) is a sectional view.

FIG. 2 is a perspective view of another example of a thermoelectric element and a coating layer.

FIGS. 3A and 3B show still another example, wherein FIG. 3A is a cross-sectional view and FIG.

4A and 4B show another example, in which FIG. 4A is a sectional view and FIG. 4B is a structural explanatory view.

5A and 5B show still another example, in which FIG. 5A is a cross-sectional view, and FIG.
FIG.

FIG. 6 is a cross-sectional view of another example.

FIG. 7 is a sectional view of still another example.

8A and 8B are cross-sectional views of another example.

FIGS. 9A and 9B are cross-sectional views of still another example.

10A and 10B are cross-sectional views of another example.

FIG. 11 is a cross-sectional view of another example.

[Explanation of symbols]

 1 thermoelectric element 2 electrode 3 coating layer

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Yoji Urano 1048 Kadoma Kadoma, Osaka Prefecture Matsushita Electric Works Co., Ltd.

Claims (11)

[Claims] 1. A thermoelectric element module in which a plurality of thermoelectric elements are electrically connected in series by a plurality of electrodes by connecting adjacent thermoelectric elements by electrodes. A thermoelectric element module, wherein the thermoelectric element module is covered with a coating layer made of an organic resin, and a space is provided between the coating layers of adjacent thermoelectric elements. 2. The thermoelectric element module according to claim 1, wherein a cylindrical element is used as the thermoelectric element. 3. The method according to claim 1, wherein the coating layers of two adjacent thermoelectric elements are connected to each other on a side opposite to an electrode electrically connecting the two thermoelectric elements. Thermoelectric module. 4. The thermoelectric element module according to claim 1, wherein the coating layers of two adjacent thermoelectric elements are connected at one end of the thermoelectric element. 5. The thermoelectric element module according to claim 1, wherein the coating layers of two adjacent thermoelectric elements are connected to each other at a central portion of the thermoelectric element. 6. The thermoelectric element module according to claim 1, wherein a polyimide layer is provided between the thermoelectric element and the coating layer. 7. The thermoelectric element module according to claim 1, wherein the coating layer is formed of a bubble-containing resin. 8. The thermoelectric device according to claim 1, wherein a thickness of a junction between the electrode and the thermoelectric element is larger than a thickness of a bridge portion connecting the junctions. Element module. 9. The thermoelectric element module according to claim 1, wherein the electrodes are joined to the thermoelectric element with solder containing fine metal balls. 10. The thermoelectric element module according to claim 1, wherein the surface of the electrode is covered with an insulating organic film. 11. The thermoelectric element module according to claim 1, wherein a joint between the electrode and the thermoelectric element is covered with a resin.