JP2000022224A - Thermoelectric element and method of manufacturing the same - Google Patents

Abstract

(57) [Summary] [PROBLEMS] To provide a thermoelectric element having excellent reliability without breakage or corrosion of each part in the element due to dew condensation and the like, and to be able to efficiently manufacture such a thermoelectric element and to improve assembling accuracy. Provided is a method for manufacturing a thermoelectric element. SOLUTION: A plurality of columnar P-type thermoelectric elements 31 and N-type thermoelectric elements 32 are arranged, and the end faces of these P-type thermoelectric elements 31 and N-type
In the thermoelectric element 10 alternately connected in series by the N-junction electrodes 12 and 22, at least a part of the outer peripheral surfaces of the P-type thermoelectric element 31 and the N-type thermoelectric element 32 are coated with the electrodeposition coating resin layer 41. I do.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelectric element capable of performing cooling and heat generation by power generation or current flow by a temperature difference, and a method of manufacturing the same.

[0002]

2. Description of the Related Art A thermoelectric element is manufactured by joining a P-type thermoelectric material and an N-type thermoelectric material via a conductive electrode such as a metal to form a PN junction pair. This thermoelectric element has a PN
Since an electromotive force based on the Seebeck effect is generated by giving a temperature difference between the junction pair, there is an application as a power generation device using the temperature difference. Conversely, there is a use as a cooling device, a heating device, or the like utilizing the Peltier effect in which a current flows through the element to cool one of the joints and generate heat at the other joint.

[0003] Such a thermoelectric element is used as a thermoelectric module in which a plurality of elements are connected in series in order to improve its performance. The structure of this thermoelectric module is such that a P-type thermoelectric element and an N-type thermoelectric element each having a rectangular parallelepiped shape having a side of several hundred μm to several mm are sandwiched between two electrically insulating substrates such as alumina and aluminum nitride. The type thermoelectric element and the N type thermoelectric element are joined on this substrate by electrodes made of a conductive material such as metal,
This joining connects the thermoelectric elements in series.

[0004] As a method of manufacturing such a thermoelectric module in which a plurality of P-type thermoelectric elements and N-type thermoelectric elements are arranged in series, generally, a P-type thermoelectric material and an N-type thermoelectric material are each heated at a temperature. After cutting into a plate having the thickness necessary to keep the difference, to join with electrodes such as metal formed on the substrate, subjected to a surface treatment such as nickel plating on both surfaces so that soldering can be performed, afterwards,
This thermoelectric material is cut into chips of a desired size, and solder for bonding is printed in advance as a wiring pattern.
There is a method of arranging and using a jig or the like on a sheet of an electrically insulating substrate such as alumina and holding them, and then joining them by heating and then soldering.

In order to reduce the size, there is also known a resin mold type thermoelectric element in which thermoelectric elements are integrated while a thermoelectric material is buried with a resin such as an epoxy resin during cutting (for example, Japanese Patent Application Laid-Open No. Hei 8-28531). JP-A-8-18109, JP-A-9-191133). Even in the case of such a small thermoelectric element, it is necessary to perform surface treatment on the end face of each thermoelectric element, and then join the joining substrates having electrodes formed on one face to both faces.

[0006]

However, when such a thermoelectric element is used as a cooling element, each part in the element is liable to be damaged or corroded due to dew condensation or the like, and the reliability is not sufficient. Therefore, after manufacturing such an element, even if an attempt is made to fill the gap with a general adhesive such as an epoxy resin used for the above-described resin mold, the gap is not sufficiently filled. Alternatively, there is a problem that the element is destroyed due to a volume change due to polymerization or the like.

As described above, the P-type thermoelectric element and N
When manufacturing with filling the resin between the mold thermoelectric element, the element cannot be manufactured with high accuracy due to the variation of the thickness of the filling layer and the like. Occurs. On the other hand, if the resin layer is omitted, P
There is a possibility that the mold material and the N-type material are short-circuited. The present invention is to solve such a problem, there is no breakage or corrosion of each part in the element due to condensation or the like, a thermoelectric element excellent in reliability, and such a thermoelectric element can be manufactured efficiently, and An object of the present invention is to provide a method for manufacturing a thermoelectric element for improving the assembling accuracy.

[0008]

According to a first aspect of the present invention for solving the above-mentioned problems, a plurality of columnar P-type thermoelectric elements and N-type thermoelectric elements are arranged, and these P-type thermoelectric elements and N-type thermoelectric elements are arranged. In a thermoelectric element in which the end faces of the element are alternately connected in series by a PN junction electrode, at least a part of the outer peripheral surfaces of the P-type thermoelectric element and the N-type thermoelectric element are coated with an electrodeposition coating resin layer. A thermoelectric element.

According to a second aspect of the present invention, in the first aspect, the electrodeposition coating resin layer is provided only on an opposing surface of the P-type thermoelectric element and the N-type thermoelectric element which is opposed to the outer peripheral surface in one direction. A thermoelectric element. A third aspect of the present invention is the thermoelectric element according to the first aspect, wherein the electrodeposition coating resin layer is provided on all of the outer peripheral surfaces of the P-type thermoelectric element and the N-type thermoelectric element. is there.

A fourth aspect of the present invention is the thermoelectric element according to the third aspect, wherein the outer peripheral surface of the PN junction electrode is also coated with an electrodeposition coating resin layer. Therefore, according to the thermoelectric element of the present invention, insulation failure due to dew condensation or the like can be prevented, and reliability can be improved. Further, the thermoelectric element of the present invention is preferably manufactured by the following manufacturing method.

That is, in a fifth aspect of the present invention, a P-type thermoelectric element and an N-type thermoelectric element are sandwiched and joined by a pair of substrates each provided with a PN junction electrode on one surface facing each other. In a method of manufacturing a thermoelectric element in which a thermoelectric element and an N-type thermoelectric element are alternately connected in series, after sandwiching and joining the P-type thermoelectric element and the N-type thermoelectric element with the pair of substrates, the method is performed by electrodeposition coating. A method for manufacturing a thermoelectric element, comprising a step of forming an electrodeposition coating resin layer on the outer peripheral surface of the P-type thermoelectric element and the N-type thermoelectric element and on the exposed portion of the PN junction electrode.

Therefore, a thermoelectric element with improved reliability can be easily formed. According to a sixth aspect of the present invention, a plurality of grooves are formed in each of the P-type thermoelectric material and the N-type thermoelectric material to form a plurality of convex portions, respectively. The projections and grooves of the mold thermoelectric material are aligned and the projections of the P-type thermoelectric material and the projections of the N-type thermoelectric material are held alternately, and then, the extending direction of these projections and Forms an alternate array of P-type thermoelectric elements and N-type thermoelectric elements by forming a second groove for cutting the convex portion in a direction orthogonal to the PN junction electrode. The method for manufacturing a thermoelectric element in which the P-type thermoelectric element and the N-type thermoelectric element are sandwiched and joined by a pair of substrates provided, and the P-type thermoelectric element and the N-type thermoelectric element are connected alternately in series. Type thermoelectric material and N type heat Electrodeposition coating is performed on at least one of the P-type thermoelectric material and the N-type thermoelectric material in a state where a groove is formed in each of the materials to form a convex portion, thereby forming an electrodeposition coating resin layer on the surface of the convex portion. The method for manufacturing a thermoelectric element comprises a step of forming a thermoelectric element.

Therefore, the entire conductive surface can be covered with the insulating layer, and the reliability is improved. According to a seventh aspect of the present invention, in the sixth aspect, the groove and the projection of the P-type thermoelectric material are combined with the projection and the groove of the N-type thermoelectric material to form the P-type thermoelectric material.
A method of manufacturing a thermoelectric element, comprising a step of filling a gap with a resin adhesive in a state where protrusions of a mold thermoelectric material and protrusions of the N-type thermoelectric material are alternately arranged.

Therefore, no insulation failure occurs when the P-type and the N-type are combined, reliability can be improved, and the yield when miniaturized is improved. According to an eighth aspect of the present invention, a P-type thermoelectric element and an N-type thermoelectric element are sandwiched and joined by a pair of substrates each provided with a PN junction electrode on one surface facing each other. In a method for manufacturing a thermoelectric element in which thermoelectric elements are connected alternately in series, after forming a columnar P-type thermoelectric material and a columnar N-type thermoelectric material, an electrodeposition coating resin layer is formed on the outer peripheral surface by electrodeposition coating. And thereafter, cutting the longitudinal lengths of the columnar P-type thermoelectric material and the columnar N-type thermoelectric material to obtain the P-type thermoelectric element and the N-type thermoelectric element. In the manufacturing method.

Therefore, it is possible to form a thermoelectric element free from the possibility of insulation failure due to condensation or the like.

[0016]

Embodiments of the present invention will be described below in detail with reference to the drawings. FIG. 1 shows a schematic diagram of a thermoelectric element according to the first embodiment of the present invention. As shown in FIG.
In the thermoelectric element 10 of the present embodiment, a plurality of P-type thermoelectric elements 31 and N-type thermoelectric elements 32 are joined and sandwiched between a first substrate 11 and a second substrate 21. Here, the first
While a plurality of electrodes 12 are provided on the upper surface of the substrate 11,
A plurality of electrodes 22 are also provided on the upper surface of the second substrate 21, and the opposing electrodes 12, 2 of these substrates 11, 21 are provided.
P-type thermoelectric element 31 and N-type thermoelectric element 3 between two
The P-type thermoelectric elements 31 and the N-type thermoelectric elements 32 are alternately wired in series by sandwiching 2 and joining the joining surfaces by soldering or the like. Then, to the electrodes 12 at both ends of the series wiring, a wiring 27 for extracting a current or flowing a current is connected via a solder 25.

Here, in the present embodiment, the conductor P
An electrodeposition coating resin layer 41 is formed to cover the entire surface of the mold thermoelectric element 31, the N-type thermoelectric element 32, the electrodes 12 and 22, and the solder 25. This electrodeposition coating resin layer 41 is made of, for example, a 20 μm thick
m. In addition, the electrodeposition coating material is not particularly limited, and may be an anion-based material or a nonionic-based material, but a material having good insulation and water resistance is preferable.

Here, a method of manufacturing such a thermoelectric element 10 of the present embodiment will be described. The thermoelectric element 10 of the present embodiment is not particularly limited, except that the electrodeposition coating resin layer 41 is entirely formed after the element is formed. Accordingly, an example of a process up to element formation is shown in FIG. First, as shown in FIG. 2A, electrodes 12 and 22 made of copper are respectively formed on the surfaces of a first substrate 11 and a second substrate 21 which are thermally conductive, and a solder layer is formed on the surfaces. On the other hand, as shown in FIG.
After plating the P-type and N-type thermoelectric materials 30 with Ni,
The resultant is cut into dice to form a P-type thermoelectric element 31 and an N-type thermoelectric element 32. Next, the P-type thermoelectric element 31 and the N-type thermoelectric element 32 are attached to the first substrate 1.
Each element and the electrode are joined by being sandwiched between the first and second substrates 22 and heated by a reflow furnace or the like. Then, after attaching the wiring 27, the thermoelectric element 10 is obtained by forming an electrodeposition coating resin layer 41 (see FIG. 1) by electrodeposition coating. The P-type thermoelectric element 3
The 1-type and N-type thermoelectric elements 32 are arranged such that, for example, the same type of elements are arranged in columns and the different types of elements are alternately arranged in rows. Although not shown, the P-type thermoelectric element 31 and the N-type thermoelectric element 3
2 is joined to the electrodes 12 and 22 after forming a nickel layer on the end face by electroless plating.

Specifically, each of the P-type and N-type thermoelectric elements 31 and 32 has a size of 0.7 mm × 0.7 mm × 1.
254 mm (height) with a plane dimension of 30 m
After being sandwiched and joined between the first substrate 11 and the second substrate 21 of mx 30 mm, an electrodeposition coating resin film 41 having a thickness of 20 μm was formed.
And the surfaces of the solder 25 and the like could be covered without pinholes. This can prevent insulation failure due to dew condensation and the like,
Reliability could be improved.

The method of manufacturing the thermoelectric element 10 according to the first embodiment is not limited to this. For example, after cutting and engaging a block-shaped P-type thermoelectric material and an N-type thermoelectric material in a comb shape, Further, a method of cutting, a method of cutting a columnar P-type thermoelectric element and an N-type thermoelectric element short and arranging them on a substrate, or a method of forming a P-type thermoelectric material and an N-type thermoelectric material in a columnar shape by a thick film method, etc. In any case, after forming the element, the electrodeposition coating is performed in the final step to form an electrodeposition coating resin layer 4.
1 may be formed.

FIG. 3 shows a thermoelectric element 1 according to a second embodiment.
FIG. Thermoelectric element 10A of the present embodiment
Has basically the same structure as the thermoelectric element 10 of the first embodiment, members having the same function are denoted by the same reference numerals, and description thereof is omitted. The thermoelectric element 10A of the present embodiment includes:
An electrodeposition coating resin layer 42 is provided only on the outer peripheral surfaces of the P-type thermoelectric element 31 and the N-type thermoelectric element 32,
No electrodeposition coating resin layer is formed on the outer surfaces of the electrodes 12 and 22. The electrodeposition coating resin layer 42 formed on the outer peripheral surfaces of the P-type thermoelectric element 31 and the N-type thermoelectric element 32 has only one side facing the outer peripheral surface in one direction (accordingly, in this case, depending on the manufacturing method). The electrodeposition coating resin layer is not formed on the front and rear surfaces of the drawing) and the electrodeposition coating resin layer 42 is formed over the entire outer peripheral surface. Further, in the present embodiment, the gap between each P-type thermoelectric element 31 and the N-type thermoelectric element 32, that is, the gap between the electrodeposition coating resin layers 42 when the electrodeposition coating resin layer 42 is formed. Is filled with a resin adhesive layer 51, but this adhesive layer 51 is not necessarily present.

FIG. 4 shows an example of the manufacturing method in the former case. First, the block-shaped P-type and N-type thermoelectric materials 30 are formed with a plurality of grooves 30a extending in one direction except a part in the thickness direction, and the plate-shaped protrusions 30b are formed in a comb-like shape. (FIGS. 4A and 4B). Specifically, for example, 15
Using a dicing machine having a blade having a width of 0 μm, grooves 30 a having a depth of 2 mm were formed at a pitch of 200 μm. Thereby, the width of the protrusion 30b becomes 50 μm. In this case, the groove was formed while leaving a part of the thermoelectric material 30 in the thickness direction. However, the groove was formed in a state where the thermoelectric material 30 was bonded to the temporary substrate, and the groove was formed over the entire thickness direction. It may be formed.

Next, a cationic electrodeposition coating (aminoacrylic resin) is applied to form an electrodeposition coating resin layer 42 on at least the outer peripheral surface of the projection 30b (FIG. 4 (c)). Next, P
With the mold thermoelectric material and the N-type thermoelectric material facing each other, one of the grooves 30a and the protrusions 30b is matched with the other of the protrusions 30b and the grooves 30a (FIG. 4D).
A low-viscosity two-component epoxy adhesive is filled in the gap between the groove 30a and the adhesive layer 51 (FIG. 4E). At this time, even if the protrusion 30b and the groove 30a may be in contact with each other, since the electrodeposition coating resin layer 42 is formed on the surface of the protrusion 30b, no trouble due to insulation failure occurs. .

Subsequently, after polishing one end surface of one of the substrates (FIG. 4F), a groove 30c orthogonal to the groove 30a is formed, and a chip portion serving as a P-type thermoelectric element and an N-type thermoelectric element is formed. 30d is formed (FIG. 4 (g)). The grooves 30c at this time were also formed at a pitch of 100 μm and a depth of 2 mm using a blade having a width of 50 μm with a dicing machine. The grooving at this time may be performed directly without polishing one end surface. When a temporary substrate is used, the groove is formed after removing the temporary substrate.

Next, the groove 30c thus formed is also
The adhesive layer 51 is formed by filling the low-viscosity two-part epoxy adhesive as described above (FIG. 4 (h)). Subsequently, the upper and lower end surfaces are polished by a lapping device or the like to obtain flatness, parallelism, and dimensions of the both end surfaces, and the thickness is set to 1.8 m.
m (FIG. 4 (i)). Thereby, each P-type thermoelectric element 31 and N-type thermoelectric element 32 are formed,
The cross-sectional dimensions of these elements are 50 μm × 50 μm,
The height is 1.8 mm.

Thereafter, an electroless nickel plating layer is selectively formed on the end faces of the elements 31 and 32, and then sandwiched between the pair of substrates 11, 21 on which the PN junction electrodes 12, 22 are formed, as described above. Thermoelectric element 10A shown in FIG.
And According to this manufacturing method, the electrodeposition coating resin layer 42 is formed on one opposing side surface of each of the elements 31 and 32, but the electrodeposition coating resin layer is not formed on the other opposing side surface. Becomes

In the manufacturing method described above, it is not always necessary to form the adhesive layer 51 after grooving (FIG. 4E). Also in this case, since the protrusion 30b of each thermoelectric material 30 is covered with the electrodeposition coating resin layer 42, no insulation failure or the like occurs. When the adhesive layer is not filled, the width of the groove 30a may be slightly larger than the width of the protrusion 30b, and the density can be further increased.

FIG. 5 shows an example of another manufacturing method. In this case, first, the P-type and N-type thermoelectric materials are converted into rod-like thermoelectric materials 35.
(FIG. 5 (a)). For example, the cross section is 0.7mm ×
The material is 0.7 mm square and 100 mm long.
Next, a cationic electrodeposition coating is applied to the outer surface of this material to form an electrodeposition coating resin layer 43 (FIG. 5B). This material was cut into, for example, 1 mm to form a P-type or N-type thermoelectric element 31 or 32 (FIG. 5C).

Thereafter, a nickel plating layer having a thickness of 2 μm is selectively applied to the cut end face by electroless plating.
The step of sandwiching and bonding to the substrate on which the N-junction electrode is formed is the same as in the above-described embodiment. As in the embodiment described above,
A thermoelectric element was formed by sandwiching a total of 254 elements between a pair of substrates having an area of 30 mm × 30 mm. According to this manufacturing method, the electrodeposition coating resin layer 42 is formed on the entire outer peripheral surface of each element, but the electrodeposition coating resin layer is not formed on the surface of the PN junction electrode.

[0030]

According to the present invention, as described above in detail in the embodiments, the outer peripheral surface of the thermoelectric element and the electrode surface are covered with an insulating layer, and there is no fear of short-circuiting. Improvement can be achieved. Further, even in the case of manufacturing a small element, there is no fear of insulation failure or the like, the failure rate can be significantly reduced, and the reliability can be improved.

[Brief description of the drawings]

FIG. 1 is a schematic diagram of a thermoelectric element according to a first embodiment of the present invention.

FIG. 2 is a diagram illustrating an example of a method for manufacturing a thermoelectric element of the present embodiment.

FIG. 3 is a schematic diagram of a thermoelectric element according to a second embodiment of the present invention.

FIG. 4 is a diagram illustrating an example of a method for manufacturing the thermoelectric element of the present embodiment.

FIG. 5 is a diagram showing another example of the method for manufacturing a thermoelectric element of the present embodiment.

[Explanation of symbols]

 10, 10A thermoelectric element 11 first substrate 12 electrode 21 second substrate 22 electrode 27 wiring 31 P-type thermoelectric element 32 N-type thermoelectric element 41, 42, 43 electrodeposition coating resin layer 51 adhesive layer

Claims (8)

[Claims] 1. A plurality of columnar P-type thermoelectric elements and N
Type thermoelectric elements are arranged, and the end faces of these P-type thermoelectric elements and N-type thermoelectric elements are alternately connected in series by PN junction electrodes. A thermoelectric element, wherein at least a part of an outer peripheral surface is coated with an electrodeposition resin layer. 2. The electrodeposition coating resin layer according to claim 1, wherein the electrodeposition coating resin layer is provided only on an opposing surface of the P-type thermoelectric element and the N-type thermoelectric element which opposes in one direction on an outer peripheral surface. Thermoelectric element. 3. The thermoelectric element according to claim 1, wherein the electrodeposition coating resin layer is provided on all outer peripheral surfaces of the P-type thermoelectric element and the N-type thermoelectric element. 4. The thermoelectric element according to claim 3, wherein the outer peripheral surface of the PN junction electrode is also coated with an electrodeposition coating resin layer. 5. A P-type thermoelectric element and an N-type thermoelectric element are sandwiched and joined by a pair of substrates each provided with a PN junction electrode on one surface facing each other, and these P-type thermoelectric elements and N-type thermoelectric elements are alternated. In the method of manufacturing a thermoelectric element connected in series to the P-type thermoelectric element and the N-type thermoelectric element, the P-type thermoelectric element and the N-type thermoelectric element are sandwiched and joined by the pair of substrates, and then the electrodeposition coating is performed. Forming an electrodeposition coating resin layer on the outer peripheral surface of the substrate and the exposed portion of the PN junction electrode. 6. A plurality of grooves are formed in each of the P-type thermoelectric material and the N-type thermoelectric material to form a plurality of protrusions, respectively.
The grooves and protrusions of the P-type thermoelectric material and the protrusions and grooves of the N-type thermoelectric material are combined to form the protrusions and the N of the P-type thermoelectric material.
By holding the protrusions of the mold thermoelectric material alternately, and forming a second groove for cutting the protrusions in a direction orthogonal to the extending direction of these protrusions, the P-type is formed. An alternating array of thermoelectric elements and N-type thermoelectric elements is formed, and then the P-type thermoelectric element and the N-type thermoelectric element are sandwiched and joined by a pair of substrates each provided with a PN junction electrode on one surface facing each other. In the method for manufacturing a thermoelectric element in which the P-type thermoelectric element and the N-type thermoelectric element are alternately connected in series, a groove is formed in each of the P-type thermoelectric material and the N-type thermoelectric material to form a convex portion. A step of forming an electrodeposition coating resin layer on the surface of the convex portion by electrodeposition coating at least one of the P-type thermoelectric material and the N-type thermoelectric material in a state in which the thermoelectric element is manufactured. Law. 7. The groove and the protrusion of the P-type thermoelectric material and the N
Filling the gap with a resin adhesive in a state in which the protrusions of the P-type thermoelectric material and the protrusions of the N-type thermoelectric material are alternately aligned with the protrusions and grooves of the mold thermoelectric material. The method for manufacturing a thermoelectric element according to claim 6, wherein 8. A P-type thermoelectric element and an N-type thermoelectric element are sandwiched and joined by a pair of substrates each provided with a PN junction electrode on one surface facing each other, and these P-type thermoelectric elements and N-type thermoelectric elements are alternated. In the method for manufacturing a thermoelectric element connected in series, a columnar P-type thermoelectric material and a columnar N-type thermoelectric material are formed, and then an electrodeposition coating resin layer is formed on the outer peripheral surface by electrodeposition coating. A method for manufacturing a thermoelectric element, comprising a step of cutting a longitudinal length of a columnar P-type thermoelectric material and a columnar N-type thermoelectric material into the P-type thermoelectric element and the N-type thermoelectric element.