JP2000332310A - Manufacture of thermoelectric module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain a high-performance thermoelectric module which can perform heat exchange with a heat source of a high temperature exceeding 300 deg.C by electrically connecting thermoelectric elements together by thermally spraying copper. SOLUTION: The method includes steps of making holes 12 for accommodation of thermoelectric elements in a substrate 11 in the form of a lattice as spaced by a predetermined interval, providing recesses 14 of a depth corresponding to nearly a thickness of electrode plates of the elements in partitions 13 defined by the adjacent holes extended from starting one of an electrically series-connected thermoelectric-element hole row to end one thereof vertically alternately, alternately arranging (p) and (n) type thermoelectric elements 21 and 22 in the holes 12 of the substrate 11, and thermally spraying copper 51 into the recesses 14 to electrically connect adjacent electrode plates 18 together with the recesses 14 disposed therebetween.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

[0001] The present invention relates to a method for manufacturing a thermoelectric module.

[0002]

2. Description of the Related Art A thermoelectric module is a module in which a p-type thermoelectric element and an n-type thermoelectric element are joined via an electrode plate so as to be electrically connected in series. When a temperature difference is applied to the thermoelectric element, a potential difference is generated. Also, when a current is passed, it has a property of absorbing or generating heat depending on the direction of the current. The former property is called the Seebeck effect and has been developed for thermoelectric power generation such as power generation by waste heat of a garbage incinerator, and the latter property is called the Peltier effect. It is widely used for thermoelectric cooling such as cooling.

As a thermoelectric module (1), as shown in FIG. 12, a p-type thermoelectric element (21) and an n-type thermoelectric element (22) to which electrodes (18) and (18) are joined are soldered (25). Some are electrically connected in series. This thermoelectric module (1) is shown in FIG.
As shown in FIG. 3, it is manufactured using an electrically insulating substrate (11). On the base (11), partition portions (13) forming holes (12) for accommodating thermoelectric elements are formed in a lattice shape, and each hole (12)
Each partition (13) has a depth substantially equivalent to the thickness of the thermoelectric element electrode plate (18) so that the thermoelectric elements are electrically connected in series when accommodated. Are formed alternately up and down. The thermoelectric elements are accommodated in the holes (12) of the base (11), and the solder (25) is poured into the recesses (14), and the electrode plates of the adjacent thermoelectric elements are electrically connected as shown in FIG. By connecting to the thermoelectric module (1), the thermoelectric module (1) is manufactured.

[0004]

The power generation efficiency of the thermoelectric module largely depends on the temperature difference applied to the thermoelectric elements. To increase the power generation efficiency, the temperature on the high temperature side must be increased and the temperature on the low temperature side must be decreased. Therefore, it is necessary to give a larger temperature difference to the thermoelectric element. The thermoelectric material varies depending on the material used. For example, in the case of a BiTe-based material, it can be used without deteriorating its performance in a temperature range up to about 350 ° C. However, the melting point of ordinary solder is about 183 ° C., and even in the case of high melting point solder, the melting point is about 285 ° C. If the temperature of the heat source in contact with the thermoelectric module is higher than the melting points of these solders, the solder will melt. As a result, sufficient conductivity cannot be maintained.
For this reason, the usable temperature of the thermoelectric module is limited by the solder, not the thermoelectric material. For example, 100
In the case of a thermoelectric module composed of individual thermoelectric elements, there are 99 solder joints between the elements. Since the thermoelectric elements are connected in series, if even one of the solder joints becomes insufficiently conductive, no current flows through the entire thermoelectric module, and the thermoelectric module does not operate. For this reason, it is very important to maintain a good electrical connection state between the thermoelectric elements when manufacturing and using the thermoelectric module.

[0005] Further, the use of lead contained in solder is being regulated, and it is desired to produce a thermoelectric module without using solder.

[0006] For this reason, the inventors have tried to braze the thermoelectric elements using a silver brazing material having a higher melting point than solder.
However, since the melting point of silver brazing is as high as 620 ° C. or higher, there has been an inconvenience that the temperature is excessively increased during brazing and the thermoelectric element is damaged.

An object of the present invention is to provide a method of manufacturing a high-performance thermoelectric module in which thermoelectric elements are electrically connected to each other by thermal spraying of copper to enable heat exchange with a heat source having a high temperature exceeding 300 ° C. And

[0008]

Means for Solving the Problems To solve the above problems, a method for manufacturing a thermoelectric element according to claim 1 of the present invention comprises:
P-type thermoelectric material (16) between a pair of opposed electrode plates (18) (18)
P-type thermoelectric element (21) and an n-type thermoelectric element (22) in which an n-type thermoelectric material (17) is joined between a pair of opposed electrode plates (18) and (18) are alternately arranged. This is a method for producing a thermoelectric module arranged in a lattice and connected so that the whole is electrically connected in series.A thermoelectric module is formed on a flat substrate (11) formed of an electrically insulating material. Holes (12) for accommodating elements are opened in a grid at predetermined intervals, and a thermoelectric element serving as the terminal end of the electric series is accommodated from the hole accommodating the thermoelectric element serving as the base end of the electric series. Forming recesses (14) of a depth substantially equivalent to the thickness of the electrode plate of the thermoelectric element alternately up and down in a partition portion (13) formed by adjacent holes and holes until the holes are formed. , A p-type thermoelectric element (2
Step of alternately arranging 1) and n-type thermoelectric element (22), base (11)
The step of spraying copper (51) on the recess (14) of the partition (13) and electrically connecting the adjacent electrode plates (18) and (18) alternately with the recess (14) interposed therebetween. Have

According to a second aspect of the present invention, there is provided a method for manufacturing a thermoelectric element according to the first aspect, wherein the opposed edges of the electrode plates (18) (18) adjacent to each other with the recess (14) interposed therebetween. The method includes a step of forming a slope in advance in order to increase a sprayed area of the copper (51) on the electrode plates (18) (18).

In the method of manufacturing a thermoelectric element according to a third aspect of the present invention, the method comprises the steps of:
P-type thermoelectric element (21) to which the type-type thermoelectric material (16) is joined, and an n-type thermoelectric element (to which an n-type thermoelectric material (17) is joined between a pair of opposed electrode plates (18) and (18)) 22) are alternately arranged in a grid pattern to produce a thermoelectric module in which the whole is electrically connected in series, wherein the flat substrate is formed of an electrically insulating material. In (11), holes (12) for accommodating thermoelectric elements are opened in a grid pattern at predetermined intervals, and a hole for accommodating a thermoelectric element serving as a base end of electric series is connected to a terminal of electric series. Until the hole in which the thermoelectric element to be housed is located, the partition (13) formed by adjacent holes and holes,
A step of alternately forming upper and lower recesses (14) recessed from the upper end surface of the partition (13); a p-type thermoelectric element (21) and an n-type thermoelectric element are formed in holes (12) of a base (11); A step of alternately arranging the elements (22) so that the electrode plate (18) is lower than the upper end surface of the partition (13); copper is inserted into the recesses (14) of the electrode plate (18) and the partition (13); (51) is sprayed.

Further, in the method for manufacturing a thermoelectric element according to claim 4 of the present invention, the copper (51) of the electrode plate (18) should be sprayed before the copper (51) is sprayed. This includes a step of performing roughening on the surface. Sand blasting can be exemplified as the rough surface processing.

[0012]

According to the method of manufacturing a thermoelectric element according to the first aspect, the electrode plates are electrically connected to each other by spraying copper (51) onto the recess (14) of the base (11). . In the case of thermal spraying, since spray-like copper is sprayed on the electrode plate (18), the amount of heat given by the copper to the thermoelectric element is small, and the element material is not damaged by the heat. Copper is less susceptible to oxidation than aluminum, the thermal resistance of the sprayed layer is low, and the coefficient of thermal expansion of copper is 16.5 × 10 ⁻⁶ / K. When BiTe is used as a thermoelectric material, It is almost the same as 16 to 18 × 10 ⁻⁶ / K, which is advantageous in that it is less susceptible to thermal stress.
Further, copper has a high thermal conductivity together with silver, and is therefore most suitable as an electrode material of a thermoelectric module for transmitting heat and electricity.

According to a second aspect of the present invention, there is provided a method for manufacturing a thermoelectric element.
By forming a slope in advance at the place where the copper (51) of the electrode plate (18) is to be sprayed, the sprayed copper (51) is not parallel to the electrode plate (18) but has an angle. Since the copper plate (51) hits the electrode plate in this state, the degree of bonding between the copper (51) and the electrode plate (18) can be increased, and the sprayed copper (51) does not crack or peel. Further, by forming the slope at the edge of the electrode plate, the area where the copper (51) is sprayed can be increased. Therefore, the electrical resistance between the sprayed copper (51) and the electrode plate (18) can be reduced, and the conductivity can be increased. By joining the electrode plates with copper (51), the electrode plates can be brought into contact with a heat source having a higher temperature (about 300 ° C. or higher) than solder, and the power generation efficiency of the thermoelectric module can be increased.

According to a third aspect of the present invention, there is provided a method for manufacturing a thermoelectric element.
Copper (51) can be sprayed at a substantially right angle to the electrode plate, and copper (51) can be sprayed on the entire surface of the electrode plate. And the degree of joining with the same. Further, since the contact area between the electrode plate and the copper (51) to be sprayed is large, the electric contact resistance at the joint can be further reduced. Since the electrode plate is joined with copper (51), it can be brought into contact with a heat source having a higher temperature (about 300 ° C. or higher) than solder, as described above, and the power generation efficiency of the thermoelectric module can be increased .

According to the method of manufacturing a thermoelectric element according to the fourth aspect, since the surface of the electrode plate (18) on which the copper (51) is sprayed is roughened, the copper (51) and the electrode Bonding with the plate can be made stronger.

[0016]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Embodiment 1 Thermoelectric Module
(1) is manufactured using a rectangular flat base (11). As shown in FIGS. 1 and 2, holes (12) for accommodating the thermoelectric material are formed in the base (11) in a lattice pattern at predetermined intervals, and adjacent holes (12) are formed. ) And the hole (12), a partition (13) is formed.

The number of holes is set based on the number of thermoelectric elements according to a desired power generation capacity. In the following, description will be made using the base body (11) having 36 holes, and in order to make the description easy to understand, in FIG. 1, the lower left hole (11) of the base body (11) serving as the base end of the electrical series connection is shown. Position 1-in order from 12)
1, position 1-2, position 1-3, and the hole (12) at the end of the electrical series connection is position 6-6. The substrate (11) is made of an electrically insulating material such as a ceramic or a heat-resistant plastic material. Desirable material for the base body (11), for example, can be mentioned cordierite _{(2MgO · 2Al 2 O 3 ·} 5SiO 2).

In the partition portion (13), recesses (14) having a depth substantially corresponding to the thickness of the electrode plate of the thermoelectric element are formed alternately in the upper and lower directions. The recess (14) is a space necessary for filling copper (51) for connecting adjacent electrode plates. More specifically, the recess (14) is located below the partition (13) between the position 1-1 and the position 1-2 (not visible in FIG. 1), the position 1-2 and the position 1-1-1. The upper and lower portions are alternately formed in the order of the upper side of the partition portion (13). For holes between adjacent rows, for example, a partition between the positions 1-6 and 2-1
A recess (14) is formed on the upper side of (13).

The base (11) has lead wires (32) for connecting devices.
Grooves (34) and (34) for receiving (32) are located at positions 1-1 and 6
-6 holes (12) and (12), respectively.

In the hole (12) of the base (11), a p-type thermoelectric element (21)
And an n-type thermoelectric element (22) are respectively housed. p-type thermoelectric element (2
1), a p-type thermoelectric material (16) is joined between a pair of opposed electrode plates (18) and (18), and the n-type thermoelectric element (22) has a pair of opposed electrode plates (18) and (18). ) Is joined to the n-type thermoelectric material (17). These thermoelectric elements are produced by placing an electrode plate (18) in a mold, filling a thermoelectric material powder thereon, placing the electrode plate (18) thereon, and hot pressing.

As an example of a p-type thermoelectric material, (Bi ₂ Te ₃ )
_1-x (Sb ₂ Te ₃ ) _x where x is 0.70 to 0.85, and as an example of an n-type thermoelectric material, (Bi ₂ Te ₃ ) _1-x (Bi ₂
Se ₃ ) _{x wherein} x is 0.05 to 0.15. The composition ratio is a ratio of the number of atoms. For the electrode plate, copper which is easy to conduct heat and electricity and has substantially the same coefficient of thermal expansion as the thermoelectric material is optimal. In order to prevent the thermoelectric material (especially Te) and the copper of the electrode plate from melting and diffusing, the copper plate is plated with Ni or Mo or Ti is deposited on the surface in contact with the thermoelectric material. It is desirable to use one.

On the electrode plate (18), thermoelectric elements (21) and (22) are
It is desirable to form a slope as shown in FIG. 3 on the end face facing the recess (14) when each is accommodated in the hole (12) of (11). The inclination can be formed by grinding or the like, and the formed inclined surface (41) is subjected to sand blasting or the like to improve the bondability of the sprayed copper (51), so that the surface is roughened. It is desirable to keep. Inclined surface (41)
Before hot pressing the electrode plate (18) with the thermoelectric material, the electrode plate (18) may be formed in advance on the electrode plate (18), or the electrode plate may be hot pressed with the thermoelectric material to form a thermoelectric element and then processed. It may be formed.

When forming the inclined surface (41), the inclination angle θ
(See FIG. 3) is preferably formed so that the gradient is 60 degrees or less, more preferably 45 degrees or less. When the gradient is larger than 60 degrees, the contact angle between the inclined surface (41) and the copper (51) to be sprayed becomes small, so the bonding between the electrode plate and the copper (51) becomes insufficient, and the thermoelectric power generation is repeated. During this time, the electrical connection between the electrode plate (18) and the copper (51) may become insufficient and the internal resistance may increase.

The inclined surface (41) is formed on at least the high-temperature side electrode plate of the pair of electrode plates of the thermoelectric element.
An inclined surface (41) may also be formed on the electrode plate on the low-temperature side, and copper may be sprayed and electrically connected similarly to the high-temperature side, but the temperature on the low-temperature side may exceed the melting point of the solder. , And may be connected by solder as in the conventional case. When the use of lead is restricted, it is desirable to form an inclined surface (41) on the low temperature side and spray copper (51). In the following, description will be made using a thermoelectric element in which inclined surfaces (41) are formed on both electrode plates (18).

A thermoelectric element having inclined surfaces (41) and (41), respectively.
As for (21) and (22), as shown in FIG. 4, the p-type thermoelectric element (2) is so set that the inclined surface (41) faces the recess (14) of the partition (13).
1) and the n-type thermoelectric element (22) are alternately accommodated. All holes (1
After accommodating the thermoelectric element in 2), copper is formed in the portion formed by the inclined surface (41) (41) and the recess (14) between the adjacent thermoelectric elements.
Spray (51). The thermal spraying is performed from a direction substantially perpendicular to the substrate (11) as shown by an arrow in FIG. Electrode plate (18)
When the inclined surface (41) is formed on the base (11),
Even if thermal spraying copper (51) from a substantially vertical direction, the inclined surface (4
Since it hits 1) at an angle, the sprayed copper (51) is sufficiently welded to the inclined surface (41). Therefore, the adjacent thermoelectric element (2
1) The conductivity between the electrode plates (18) and (18) of (22) does not decrease.

After the thermal spraying of copper (51) on both surfaces of the substrate (11), the surface is ground as shown by a dashed line in FIG. 6 to produce a thermoelectric module as shown in FIG. . In addition, lead wires (32) (32) for device connection are inserted into the grooves (34) (34) of the base (11), and the p-type thermoelectric element at the position 1-1 is inserted.
(21) (base end of electrical series) and n-type thermoelectric element at positions 6-6
(22) Connect to (Electrical series termination) electrode plate (18) respectively
(See FIG. 7).

<Embodiment 2> In Embodiment 2, the thermoelectric elements (21) (2)
As shown in FIG. 8, when the electrode plate 2 is accommodated in the hole 12 of the base 11, the electrode plate is formed smaller than the partition portion 13. As shown in FIG. The thermoelectric elements (21) and (22) are electrically connected to both the electrode plate (18) and the recess (14) by spraying copper (51) from a substantially right angle direction.

Since the sprayed copper (51) layer is formed on the electrode plate (18), the thickness of the electrode plate (18) is reduced in consideration of the thermal spraying allowance of the copper (51). It is desirable to keep. Electrode plate (1
8) is desirably about 0.2 to 0.7 mm in thickness. To form a thin electrode plate (18) on the thermoelectric material (16) (17), a thin electrode plate (18) formed in advance is hot-pressed on the thermoelectric material, or a thicker electrode plate (18) is Hot pressing, and then the surface of the electrode plate (18) may be ground by surface grinding or the like. Copper sprayed on the surface of the electrode plate (18)
In order to increase the degree of bonding with (51), it is desirable that a portion to be sprayed with copper (51) be roughened in advance by sandblasting or the like.

As the base (11), the same one as in the first embodiment can be used. As shown in FIG. 8, the thermoelectric elements (21) and (22) are placed on the electrode plate (18) rather than the partition (13). )
Place it in (12). In this state, as shown in FIG. 9, copper (51) was sprayed on the electrode plate (18) and the concave portion (14) of the partition portion (13),
Electrode plates (18) of adjacent thermoelectric elements (21) (22) are connected to each other by thermal sprayed copper (51). The thermal spraying is performed from a direction substantially perpendicular to the substrate (11) as shown by an arrow in FIG.

After the copper (51) is sprayed on both sides of the substrate (11), as shown by the dashed line in FIG. 10, the tip of the partition (13) where the recess (14) is not formed is exposed. Surface grinding is performed to the extent necessary, and the lead wire for connecting the equipment as in the first embodiment.
By connecting (not shown), a thermoelectric module (1) in which thermoelectric elements are connected in series is manufactured.

In this embodiment, the electrode plate is made of copper
(51) can be sprayed substantially at a right angle, and copper (51) can be sprayed on the entire surface of the electrode plate. It can be further increased compared to 1. Also, copper sprayed with the electrode plate
Since the contact area with (51) is large, the electrical contact resistance at the joint can be reduced.

In the second embodiment as well, the bonding of the electrode plates (18) and (18) by thermal spraying of copper (51) may be performed at least on the surface on the high temperature side of the thermoelectric module (1). The electrode plate may be joined to the low-temperature side by soldering. In the case of soldering, the electrode plate need not be thinned.

[0033]

EXAMPLE Regarding the thermoelectric module of Example 2, a thermoelectric element was formed by spraying copper (51) only on one side to join the thermoelectric elements and joining the other side by soldering.
Heat the high temperature side until the temperature difference between both sides of the thermoelectric module is about 300 ° C (low temperature side is room temperature), and after maintaining for 30 minutes,
The power generation output when the temperature was lowered until the temperature difference reached about 80 ° C. was measured. The results are shown in FIG. Referring to FIG. 11, the power generation output of the thermoelectric module increases almost in proportion to the square of the temperature difference, and the output is stable even when the temperature difference is about 300 ° C. In addition, the power generation output at the time of temperature rise and the power output at the time of temperature fall were the same within the measurement error range, and reproducibility was obtained. As described above, the thermoelectric module of the present invention can be used in a temperature range higher than the working temperature of the conventional thermoelectric module by soldering (less than the melting point of solder), and its output is reproducible and stable. You can see that it is.

The description of the above embodiments is for the purpose of illustrating the present invention, and should not be construed as limiting the invention described in the appended claims or reducing the scope thereof. Further, the configuration of each part of the present invention is not limited to the above embodiment, and various modifications can be made within the technical scope described in the claims.

[Brief description of the drawings]

FIG. 1 is a plan view of a base.

FIG. 2 is a sectional view taken along line AA of FIG.

FIG. 3 is a perspective view of a thermoelectric element used in the first embodiment.

FIG. 4 is a cross-sectional view of the base of the first embodiment in a state in which a thermoelectric element is housed.

FIG. 5 is an enlarged sectional view of a sprayed portion of copper.

FIG. 6 is a cross-sectional view of the substrate after thermal spraying of copper.

FIG. 7 is a perspective view of a thermoelectric module.

FIG. 8 is a cross-sectional view of a base body according to a second embodiment in which a thermoelectric element is housed.

FIG. 9 is a cross-sectional view of the base body showing a state where copper is being thermally sprayed.

FIG. 10 is a cross-sectional view of the substrate after thermal spraying of copper.

FIG. 11 is a graph showing a power generation output when a temperature difference is given to the thermoelectric module of the present invention.

FIG. 12 is a sectional view of a conventional thermoelectric module.

FIG. 13 is a cross-sectional view illustrating a process of assembling a conventional thermoelectric module.

[Explanation of symbols]

 (1) Thermoelectric module (11) Base (13) Partition (14) Recess (21) P-type thermoelectric element (22) N-type thermoelectric element (41) Inclined surface (51) Copper

Claims (4)

[Claims] 1. A p-electrode between a pair of opposed electrode plates (18) (18).
P-type thermoelectric element (21) to which the type-type thermoelectric material (16) is joined, and an n-type thermoelectric element (to which an n-type thermoelectric material (17) is joined between a pair of opposed electrode plates (18) and (18)) 22) are alternately arranged in a grid pattern to produce a thermoelectric module in which the whole is electrically connected in series, comprising: a plate-shaped base formed from an electrically insulating material. (11)
At the same time, holes (12) for accommodating thermoelectric elements are opened in a grid pattern at predetermined intervals, and a thermoelectric element, which serves as a terminal end of an electric series, is opened from a hole for accommodating a thermoelectric element serving as a base end of an electric series. Until the hole in which the element is accommodated, recesses (14) with a depth approximately equivalent to the thickness of the electrode plate of the thermoelectric element are alternately arranged up and down in the partition (13) formed by adjacent holes and holes. Forming, a step of alternately arranging p-type thermoelectric elements (21) and n-type thermoelectric elements (22) in holes (12) of the base (11), and forming a partition (13) of the base (11). A step of spraying copper (51) on the recess (14) and alternately electrically connecting the electrode plates (18) (18) adjacent to each other with the recess (14) interposed therebetween. How to make a module. 2. Electrode plates (18) (1) adjacent to each other across a recess (14).
The thermoelectric module according to claim 1, further comprising a step of forming a slope on the opposite edge of (8) in order to increase a sprayed area of the copper (51) on the electrodes (18). Method of manufacturing. 3. A voltage p between a pair of opposed electrode plates (18) (18).
P-type thermoelectric element (21) to which the type-type thermoelectric material (16) is joined, and an n-type thermoelectric element (to which an n-type thermoelectric material (17) is joined between a pair of opposed electrode plates (18) and (18)) 22) are alternately arranged in a grid pattern to produce a thermoelectric module in which the whole is electrically connected in series, comprising: a plate-shaped base formed from an electrically insulating material. (11)
At the same time, holes (12) for accommodating thermoelectric elements are opened in a grid pattern at predetermined intervals, and a thermoelectric element, which serves as a terminal end of an electric series, is opened from a hole for accommodating a thermoelectric element serving as a base end of an electric series. Until the hole in which the element is housed, recesses (14) recessed from the upper end surface of the partition (13) are alternately formed in the partition (13) formed by adjacent holes and holes. In the process, in the hole (12) of the base (11), the p-type thermoelectric element (21) and the n-type thermoelectric element (22) are arranged such that the electrode plate (18) is lower than the upper end surface of the partition (13). And a step of spraying copper (51) on the electrode plate (18) and the recess (14) of the partition part (13), so that the adjacent thermoelectric elements (21) and (22) A method for manufacturing a thermoelectric module, comprising connecting electrode plates (18) with thermally sprayed copper (51). 4. The method according to claim 1, wherein the electrode plate (18) includes a step of performing a roughening process on a surface on which the copper (51) is to be thermally sprayed before the thermal spraying. Method for manufacturing a thermoelectric module.