JP2017045970A - Thermoelectric module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric module excellent in reliability, by suppressing deformation due to thermal expansion difference, even if one of two circuits connected in parallel is disconnected.SOLUTION: A thermoelectric module 10 includes a pair of support substrates placed to face each other, wiring conductors provided on one-side principal surfaces opposed to the pair of support substrates, respectively, and a plurality of thermoelectric elements 4 placed side by side, in plan view, between the one-side principal surfaces opposed to the pair of support substrates, and constituting a first circuit 31 by being connected in series and a second circuit 32 by being connected in series. The first circuit 31 and the second circuit 32 are connected in parallel with each other and meander, and the second circuit 32 is placed along the first circuit 31.SELECTED DRAWING: Figure 2

Description

  The present invention relates to a thermoelectric module used for thermoelectric power generation such as temperature control or waste heat power generation of, for example, a thermostatic bath, a refrigerator, an automotive seat cooler, a semiconductor manufacturing apparatus, a laser diode or a fuel cell, a battery, .

  The thermoelectric module can generate a temperature difference between one main surface and the other main surface, for example, by supplying electric power to the thermoelectric element. Moreover, the thermoelectric module can generate electric power by a thermoelectric element by giving a temperature difference between one main surface and the other main surface, for example. Taking advantage of these properties, thermoelectric modules are used for temperature control or thermoelectric generation.

  As such a thermoelectric module, a pair of support substrates arranged so as to face each other, wiring conductors respectively provided on one main surface of the pair of support substrates facing each other, and one main surface of the pair of support substrates facing each other A plurality of thermoelectric elements that are arranged side by side between the planes and are connected in series to form the first circuit or the second circuit, and the first circuit and the second circuit are connected in parallel to each other A thermoelectric module having such a configuration is known (see Patent Document 1). In the thermoelectric module of Patent Document 1, the first circuit is provided along the outer periphery of the support substrate, and the second circuit meandering in the inner region is provided so as to be surrounded by the first circuit. Yes.

JP 2013-161973 A

  However, in the thermoelectric module disclosed in Patent Document 1, since the first circuit is formed so as to surround the second circuit, when one of the circuits is disconnected, the outer peripheral portion and the inner region This causes a temperature difference, and the thermoelectric module is deformed due to a difference in thermal expansion. Therefore, in the other circuit, a crack occurs in the junction between the thermoelectric element and the wiring conductor, and the resistance value as the circuit increases, thereby reducing the reliability. There is a fear.

  The present invention has been made in view of such problems, and its purpose is to suppress deformation due to a difference in thermal expansion even when one of two circuits connected in parallel is disconnected, and has excellent reliability. It is to provide a thermoelectric module.

  The thermoelectric module of the present invention includes a pair of support substrates disposed so as to face each other, wiring conductors respectively provided on one opposing main surface of the pair of support substrates, and one of the pair of support substrates facing each other A first circuit and a plurality of thermoelectric elements that are connected in series to form a second circuit, arranged side by side in a plan view between the main surfaces, the first circuit and the first circuit The two circuits are connected in parallel to each other, the first circuit and the second circuit meander together, and the second circuit is arranged along the first circuit. It is a feature.

  According to the present invention, a temperature difference is unlikely to occur between the outer peripheral portion and the inner region of the thermoelectric module even when the wire is disconnected, so that it is possible to suppress deformation due to a difference in thermal expansion and to have excellent reliability. it can.

(A) is a partially-omission schematic perspective view of an example of the thermoelectric module which concerns on this embodiment, (b) is a partial permeation | transmission side view of the thermoelectric module shown to (a). It is explanatory drawing of the circuit pattern of the thermoelectric module shown in FIG. It is explanatory drawing of the circuit pattern of the other example of the thermoelectric module which concerns on this embodiment. It is explanatory drawing of the circuit pattern of the other example of the thermoelectric module which concerns on this embodiment. It is explanatory drawing of the circuit pattern of the other example of the thermoelectric module which concerns on this embodiment. It is a permeation | transmission side view of the other example of the thermoelectric module which concerns on this embodiment. It is explanatory drawing of the circuit pattern of the thermoelectric module used as a comparative example.

  Hereinafter, an example of the thermoelectric module according to the present embodiment will be described with reference to the drawings.

  FIG. 1A is a partially omitted schematic perspective view of an example of a thermoelectric module according to the present embodiment, and FIG. 1B is a partially transparent side view of the thermoelectric module shown in FIG. FIG. 2 is an explanatory diagram of a circuit pattern of the thermoelectric module shown in FIG. In FIG. 1A, the sealing material shown in FIG. 1B is omitted.

  A thermoelectric module 10 shown in FIGS. 1 and 2 includes a pair of support substrates 11 and 12 disposed so as to face each other, and wiring conductors 2 provided on one main surface of the pair of support substrates 11 and 12 facing each other. Are arranged in a plan view between the opposing main surfaces of the pair of support substrates 11 and 12, and are connected in series to form the first circuit 31 and the plurality of circuits that are connected in series to form the second circuit 32. The first circuit 31 and the second circuit 32 are connected in parallel to each other, and the first circuit 31 and the second circuit 32 meander together to form the first circuit 31. The second circuit 32 is arranged along the line.

  The pair of support substrates 11 and 12 constituting the thermoelectric module 10 according to the present embodiment has a thickness of 50 to 500 μm on the outer main surface of an epoxy resin plate (substrate body) having a thickness of 50 to 200 μm to which, for example, an alumina filler is added. The copper substrates are bonded together, and the support substrates 11 and 12 are arranged so as to face each other.

  The support substrates 11 and 12 may have a configuration in which a metal plate such as copper is bonded to the outer main surface of a substrate body made of a ceramic material such as alumina or aluminum nitride. A configuration in which an insulating layer made of epoxy resin, polyimide resin, alumina, aluminum nitride, or the like is provided on the inner main surface of the substrate body made of a conductive material such as palladium may be used.

  The dimensions when the support substrates 11 and 12 are viewed in plan are, for example, 40 to 80 mm in length and 20 to 40 mm in width.

  A wiring conductor 2 is provided on each of the opposing main surfaces of the pair of support substrates 11 and 12. The wiring conductor 2 is formed, for example, by etching a copper plate bonded to the inner main surface of the support substrates 11 and 12 into a wiring pattern, and between a p-type thermoelectric element 41 and an n-type thermoelectric element 42 described later. It is provided so as to be electrically connected in series. The material for forming the wiring conductor 2 is not limited to copper, and may be a material such as silver or silver-palladium.

  A plurality of thermoelectric elements 4 (p-type thermoelectric elements 41 and n-type thermoelectric elements 42) are connected between the opposing inner main surfaces of the pair of support substrates 11 and 12 by the wiring conductor 2. It is arranged.

The plurality of thermoelectric elements 4 are thermoelectric materials composed of A ₂ B ₃ type crystals (A is Bi and / or Sb, B is Te and / or Se), preferably bismuth (Bi) or tellurium (Te) thermoelectric material The main body is formed. Specifically, the p-type thermoelectric element 41 is formed of, for example, a thermoelectric material made of a solid solution of Bi ₂ Te ₃ (bismuth telluride) and Sb ₂ Te ₃ (antimony telluride), and the n-type thermoelectric element 42 is For example, it is formed of a thermoelectric material made of a solid solution of Bi ₂ Te ₃ (bismuth telluride) and Bi ₂ Se ₃ (bismuth selenide).

Here, the thermoelectric material used as the p-type thermoelectric element 41 is once melted and solidified, and a p-type thermoelectric material composed of Bi _, Sb and Te is solidified in one direction by the Bridgman method, for example, a diameter of 0.5 to 3 mm. This is a rod-shaped body having a circular cross section. In addition, the thermoelectric material to be the n-type thermoelectric element 42 is an n-type thermoelectric material composed of Bi, Te and Se once melted and solidified in one direction by the Bridgman method, for example, a diameter of 0.5 to 3 mm. This is a rod-shaped body having a circular cross section.

  If necessary, after coating a resist for preventing plating from adhering to the side surfaces of these thermoelectric materials, the wire is cut into a width (thickness) of, for example, 0.3 to 5.0 mm. Then, if necessary, a Ni layer is formed only on the cut surface by, for example, electroplating, an Sn layer is formed thereon, and the resist is peeled off with a solution, whereby the thermoelectric element 4 (p-type thermoelectric elements 41, n Type thermoelectric element 42) can be obtained.

  The shape of the thermoelectric element 4 may be a columnar shape, a quadrangular columnar shape or a polygonal columnar shape, but a cylindrical shape is preferable in order to avoid stress concentration accompanying expansion and contraction during use.

  A plurality of the thermoelectric elements 4 are arranged in rows and columns at intervals of 0.5 to 2.0 mm, for example, 0.5 to 2.0 times the thermoelectric element size (diameter). The thermoelectric element 4 is joined to the wiring conductor 2 by a solder paste applied in the same pattern as the wiring conductor 2, and the plurality of arranged thermoelectric elements 4 are electrically connected by the wiring conductor 2.

  The plurality of thermoelectric elements 4 arranged side by side in a plan view are connected in series to form a first circuit 31 or a second circuit 32 as shown in FIG. Furthermore, the first circuit 31 and the second circuit 32 are connected in parallel to each other, and the first circuit 31 and the second circuit 32 meander together, and the second circuit so as to follow the first circuit 31. Circuit 32 is arranged. FIG. 2 shows an electrical connection path (circuit pattern) composed of a plurality of thermoelectric elements 4 and wiring conductors 2 when the thermoelectric module 10 shown in FIG.

  Specifically, the first circuit 31 extends in the vertical direction at the outer peripheral portion between the one main surfaces of the support substrates 11 and 12, then extends in the horizontal direction at the outer peripheral portion, and is bent near the central portion in the horizontal direction. A pattern extending so as to longitudinally cut a central portion between the one main surfaces of the support substrates 11 and 12 is provided from both ends in the width direction between the one main surfaces of the support substrates 11 and 12, respectively. Has a connected shape. As a result, the first circuit 31 has a meandering shape.

  On the other hand, the second circuit 32 extends along the second circuit starting from the inside of the first circuit 31, and the second circuit 32 also has a meandering shape.

Here, the distance between the first circuit 31 and the second circuit 32 is, for example, the shortest distance (perpendicular length) at a position where these circuits are parallel to each other, for example, 0.5 to 3 mm, and the thermoelectric element size (diameter). ) Is set to 0.5 to 2.0 times.

  In the thermoelectric module in which the first circuit 71 as shown in FIG. 7 is formed so as to surround the second circuit 72, when one of the circuits is disconnected, a temperature difference occurs between the outer peripheral portion and the inner region. The thermoelectric module may be deformed due to a difference in thermal expansion, and reliability may be reduced. On the other hand, according to the configuration shown in FIGS. 1 and 2, even if one of the first circuit 31 and the second circuit 32 is disconnected, the parallel circuit is likely to be shifted. Therefore, the temperature difference between the outer peripheral portion of the thermoelectric module 10 in plan view and the inner region is less likely to occur, and the module is less likely to be deformed due to the difference in thermal expansion. Therefore, it is possible to suppress an increase in resistance value due to a crack at the junction between the thermoelectric element 4 and the wiring conductor 2 in the other circuit, and to improve the reliability of the thermoelectric module.

  The pattern in which the first circuit 31 and the second circuit 32 meander is not limited to the form shown in the figure, and the number of times of bending may be larger. Although not shown, the circuits in parallel relation are not limited to the two circuits of the first circuit 31 and the second circuit 32, and may be three or more.

  FIG. 3 is an explanatory diagram of a circuit pattern of another example of the thermoelectric module according to the present embodiment. As shown in FIG. 3, the number of the plurality of thermoelectric elements 4 constituting the first circuit 31 may be the same as the number of the plurality of thermoelectric elements constituting the second circuit 32. By doing so, the resistance values of the first circuit 31 and the second circuit 32 are substantially the same, and the current values flowing to the respective circuits are substantially equal. Therefore, substantially uniform cooling and heating can be performed on the surface of the thermoelectric module 10.

  FIG. 4 is an explanatory diagram of another example circuit pattern of the thermoelectric module according to the present embodiment. As shown in FIG. 4, the first circuit 31 and the second circuit 32 may be connected at a plurality of portions having the same potential. In addition, the connection in the site | part which becomes the same electric potential is obtained by setting it as the pattern which connects the wiring conductor 2 electrically in this site | part. According to this configuration, when a part of the first circuit 31 or the second circuit 32 is disconnected, only the vicinity of the disconnected part, that is, the connection of the part having the same potential on the upstream side of the disconnected part is connected. Since the current only stops flowing only at the disconnected circuit side between the location and the connection location of the portion having the same potential on the downstream side, the performance degradation of the thermoelectric module 10 can be further reduced even if the location is disconnected.

  FIG. 5 is an explanatory diagram of a circuit pattern of another example of the thermoelectric module according to the present embodiment. As shown in FIG. 5, at least a part of the first circuit 31 is provided on the outer periphery of the support substrates 11 and 12, and the first circuit 31 provided on the outer periphery of the support substrates 11 and 12 is changed. The density of the arrangement of the plurality of thermoelectric elements 4 to be configured may be higher than the density of the arrangement of the plurality of thermoelectric elements 4 that constitute the first circuit 31 in the other part. In the example shown in FIG. 5, the intervals between the plurality of thermoelectric elements 4 constituting the first circuit 31 provided on the outer peripheral portions of the support substrates 11 and 12 are the plurality of thermoelectric elements arranged in the other inner region. By narrowing the interval between the elements 4, the density of the arrangement of the plurality of thermoelectric elements 4 constituting the first circuit 31 provided on the outer peripheral portions of the support substrates 11 and 12 is increased.

  As a configuration for increasing the arrangement density of the plurality of thermoelectric elements 4, the interval between the plurality of thermoelectric elements 4 constituting the first circuit 31 provided on the outer peripheral portions of the support substrates 11 and 12 is set to the other inner region. What is necessary is just to adjust suitably besides making it narrower than the space | interval of the several thermoelectric element 4 arrange | positioned in this.

  According to this configuration, it is possible to prevent a temperature drop in the outer peripheral portion from which heat escapes, so that a temperature difference between the outer peripheral portion in a plan view of the thermoelectric module 10 and the inner region is less likely to occur, and deformation of the module due to a difference in thermal expansion is prevented. Furthermore, it can suppress and can improve the reliability of a thermoelectric module more.

  In addition, as shown in FIG. 1, the outer peripheral part between the one main surfaces of the support substrates 11 and 12 may be closed with a sealing material 5 made of epoxy resin, silicon resin, or the like, whereby dew condensation inside the thermoelectric module 10 occurs. Can be prevented, and leakage and damage due to current leakage can also be suppressed.

  FIG. 6 is a schematic cross-sectional view of another example of the thermoelectric module according to the present embodiment. The thermoelectric module 20 shown in FIG. 6 has a heat exchange fin 6 attached to the other main surface outside the pair of support substrates 11 and 12 via a bonding material (not shown). Thus, the heat exchange efficiency of the thermoelectric module can be increased. As the heat exchange fin 6, copper, aluminum, iron, or the like having high thermal conductivity can be used, and as shown in FIG. Including a plurality of standing parts erected from the bottom part and a plurality of top surface parts connecting adjacent standing parts, and a plate-like body bent so as to meander in a cross section, etc. Can be preferably used.

  Hereinafter, the present invention will be described in more detail with reference to examples.

First, a p-type thermoelectric material and an n-type thermoelectric material made of bismuth, antimony, tellurium, and selenium were melted and solidified by the Bridgman method to produce a rod-shaped material having a circular cross section with a diameter of 1.4 mm. Specifically, the p-type thermoelectric material is made of a solid solution of Bi ₂ Te ₃ (bismuth telluride) and Sb ₂ Te ₃ (antimony telluride), and the n-type thermoelectric material is Bi ₂ Te ₃ (bismuth telluride). And Bi ₂ Se ₃ (bismuth selenide).

  Next, the rod-shaped p-type thermoelectric material and the rod-shaped n-type thermoelectric material whose side surfaces are coated with a resist coat layer are cut with a wire saw so as to have a height (thickness) of 1.0 mm. And the n-type thermoelectric element was obtained. A nickel layer and a tin layer were formed on the cut surface by electrolytic plating on the obtained p-type thermoelectric element and n-type thermoelectric element, thereby producing a thermoelectric element.

  Next, a substrate having a three-layer structure of Cu layer / epoxy resin layer / Cu layer in the thickness direction was prepared as a support substrate. The Cu layer on the upper surface of the support substrate was etched so as to form an electrode pattern that electrically connected the thermoelectric elements in series, thereby providing a wiring conductor.

  Next, an Sb—Sn solder paste is applied to the wiring conductor on which the p-type thermoelectric element and the n-type thermoelectric element are arranged, and the p-type thermoelectric element and the n-type thermoelectric element are spaced apart from each other and a pair of support substrates Are alternately arranged on the wiring conductor on one of the supporting substrates (first supporting substrate), and the other supporting substrate (on the p-type thermoelectric element and n-type thermoelectric element via the wiring conductor) After the second support substrate) is placed, the Sb—Sn solder paste is melted by heating, the thermoelectric element and the wiring conductor are joined by soldering, and then the short side of the outer peripheral portion between one main surface of the support substrate Was sealed with a sealing material made of epoxy resin and the long side with silicon resin.

  Subsequently, as shown in FIG. 6, a heat exchange fin made of copper is attached to the main surface on the outer side of the support substrate using Sn—Bi solder as a bonding material, and then power is supplied to the wiring conductor. The lead wires were connected to produce a thermoelectric module for evaluation.

  As this thermoelectric module, a thermoelectric module as an example and a thermoelectric module as a comparative example were produced. Specifically, thermoelectric modules (samples 1 to 3) serving as examples of the circuit pattern shown in FIG. 2 were produced. Note that the first circuit and the second circuit are both in a conductive state as the sample 1, the one in which only the first circuit is disconnected as the sample 2, and the second as the sample 3. The one that only the circuit of was disconnected was prepared.

  On the other hand, as a comparative example, as shown in FIG. 7, the second circuit is not provided along the first circuit, and only the second circuit meanders in the inner region. Sample 4) was also prepared. In Sample 4, only the second circuit was disconnected.

And about the produced thermoelectric module of the samples 1-4, in the state which let the gas of fixed air volume pass with the fan in the state which sealed the circumference | surroundings of the lower side heat exchange fin and the upper side heat exchange fin, durability as reliability confirmation Was evaluated. The durability was evaluated by applying a voltage of 12 V to the thermoelectric module with the air flow being 7 m ³ / h and blowing to the lower and upper heat exchange fins, and inverting the applied voltage every 15 seconds. The resistance change rate before and after the test was measured for 100 cycles. The results are shown in Table 1.

  According to the result of Table 1, it turns out that the resistance change rate of the thermoelectric module (samples 1-3) used as an Example is very low compared with the thermoelectric module (sample 4) used as a comparative example. That is, even if one of the parallel circuits in the thermoelectric module of the example is disconnected, the deformation of the thermoelectric module is small, so that it can be seen that the resistance change rate is small and the reliability (durability) is excellent.

10, 20: Thermoelectric modules 11, 12: Support substrate 2: Wiring conductor 31: First circuit 32: Second circuit 4: Thermoelectric element 41: p-type thermoelectric element 42: n-type thermoelectric element 5: sealant 6: fin

Claims (4)

A pair of support substrates disposed so as to oppose each other, wiring conductors respectively provided on one opposing main surface of the pair of support substrates, and one opposing main surface of the pair of support substrates in a plan view A plurality of thermoelectric elements arranged side by side and connected in series to form a first circuit and connected in series to form a second circuit;
The first circuit and the second circuit are connected in parallel to each other, and the first circuit and the second circuit meander together, and the second circuit extends along the first circuit. A thermoelectric module in which a circuit is arranged.   2. The thermoelectric module according to claim 1, wherein the number of the plurality of thermoelectric elements constituting the first circuit is the same as the number of the plurality of thermoelectric elements constituting the second circuit.   The thermoelectric module according to claim 1 or 2, wherein the first circuit and the second circuit are connected at a plurality of portions having the same potential. At least a part of the first circuit is provided on the outer peripheral portion of the support substrate, and the density of the arrangement of the plurality of thermoelectric elements constituting the first circuit provided on the outer peripheral portion of the support substrate is: 4. The thermoelectric module according to claim 1, wherein the thermoelectric module has a density higher than a density of arrangement of a plurality of thermoelectric elements in another part constituting the first circuit. 5.

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