JP2018018908A - Thermoelectric converter - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric converter capable of easily and surely connecting a lead wire to a lead wire electrode. SOLUTION: A thermoelectric converter 1 includes a substrate 20, a group of electrodes 203 formed on the upper surface of the substrate 20, a plurality of thermoelectric conversion elements 30 whose lower surface is joined to a group of electrodes 203, and a plurality of thermoelectric conversion elements 30. It is provided with a group of electrodes 101 bonded to the upper surface of the above. A groove is formed on the lower surface of the substrate 20 so as to surround the lead wire electrodes 203a and 203b to which the lead wires 40a and 40b are connected in the electrode 203 group in a plan view. [Selection diagram] Fig. 2

Description

  The present invention relates to a thermoelectric converter that converts heat into electric power or converts electric power into heat.

  Conventionally, thermoelectric converters are used to cool or heat an object. In recent years, thermoelectric converters are used to convert exhaust heat generated in factories and the like into electric power. This type of thermoelectric converter can be configured by combining a number of p-type thermoelectric conversion elements and n-type thermoelectric conversion elements using thermoelectric effects such as Seebeck effect, Peltier effect, or Thomson effect.

  Patent Document 1 below describes a thermoelectric converter in which a large number of thermoelectric conversion elements are arranged between two substrates. In this configuration, a plurality of slit-like grooves are provided in the substrate at locations other than the joints with the electrodes in order to suppress the occurrence of warpage due to thermal strain in the substrate.

JP 2000-68564 A

  In general, in a thermoelectric converter, thermoelectric conversion elements between substrates are connected in series by an electrode group formed on each substrate. Furthermore, in order to connect the thermoelectric conversion elements connected in series to an external circuit, a lead wire is connected to a lead wire connecting electrode (lead wire electrode) formed on the substrate. Here, the lead wires are connected using solder. That is, after the two substrates are overlaid on the upper and lower surfaces of the thermoelectric conversion element and each electrode is joined to the thermoelectric conversion element, the lead wire is soldered to the upper surface of the lead wire electrode.

  However, in a thermoelectric converter, in order to improve thermoelectric conversion efficiency, a board | substrate may be formed with metal materials with high heat conductivity, such as copper and aluminum. At this time, if heat is applied to the lead wire electrode during soldering of the lead wire, this heat is conducted and diffused to the substrate, and it is difficult for the heat to be accumulated at the joint location. As a result, the lead wire cannot be properly connected to the lead wire electrode.

  In view of such a problem, an object of the present invention is to provide a thermoelectric converter capable of easily and reliably connecting a lead wire to a lead wire electrode.

  A thermoelectric converter according to a main aspect of the present invention includes a substrate, a first electrode group formed on an upper surface of the substrate, a plurality of thermoelectric conversion elements whose lower surface is bonded to the first electrode group, And a second electrode group bonded to the upper surfaces of the plurality of thermoelectric conversion elements. Here, a groove is formed on the lower surface of the substrate so as to surround a lead wire electrode to which a lead wire is connected in the first electrode group in a plan view.

  According to the thermoelectric converter according to this aspect, since the groove is formed on the lower surface of the substrate so as to surround the lead wire electrode in a plan view, it is added to the lead wire electrode during soldering of the lead wire. Even if the heat is conducted to the substrate immediately below, the groove becomes a barrier, and the heat is further prevented from diffusing around. For this reason, the heat applied for soldering tends to accumulate on the lead wire electrode. Therefore, it is possible to easily and reliably solder the lead wire to the lead wire electrode.

  As described above, according to the present invention, it is possible to easily and reliably connect the lead wire to the lead wire electrode.

  The effects and significance of the present invention will become more apparent from the following description of embodiments. However, the embodiment described below is merely an example when the present invention is implemented, and the present invention is not limited to what is described in the following embodiment.

FIG. 1A is an exploded perspective view schematically showing the configuration of the thermoelectric converter according to the embodiment. FIG.1 (b) is a perspective view which shows typically the state after the assembly of the thermoelectric converter which concerns on embodiment. 2A and 2B are diagrams schematically showing a lead wire connecting step according to the embodiment. FIG. 3 is a rear view illustrating a groove formation state of the thermoelectric converter according to the first embodiment. FIG. 4A is a plan view of the vicinity of the groove of the thermoelectric converter according to the first embodiment when viewed from the back surface side. FIG. 4B is a cross-sectional view of the vicinity of the groove of the thermoelectric converter according to the first embodiment cut along a plane perpendicular to the substrate. FIG. 5 is a rear view illustrating a groove formation state of the thermoelectric converter according to the second embodiment. FIG. 6A is a plan view of the vicinity of the groove of the thermoelectric converter according to the second embodiment when viewed from the back surface side. FIG. 6B is a cross-sectional view in which the vicinity of the groove of the thermoelectric converter according to Modification 1 is cut along a plane perpendicular to the substrate. Fig.7 (a) is the top view which looked at the groove | channel vicinity of the thermoelectric converter which concerns on the modification 2 from the back surface side. FIG. 7B is a plan view of the vicinity of the groove of the thermoelectric converter obtained by further modifying the modification 2 as viewed from the back surface side. FIG. 8A is a plan view of the vicinity of the groove of the thermoelectric converter according to Modification 4 as viewed from the back side. FIG. 8B is a plan view of the vicinity of the groove of the thermoelectric converter according to Modification 5 as viewed from the back surface side.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. For convenience, the X, Y, and Z axes that are orthogonal to each other are appended to each drawing. The Z-axis direction is the height direction of the thermoelectric converter 1, and the Z-axis positive direction is the downward direction.

  FIG. 1A is an exploded perspective view showing a configuration of the thermoelectric converter 1, and FIG. 1B is a perspective view showing a state after the thermoelectric converter 1 is assembled.

  As shown in FIG. 1A, the thermoelectric converter 1 includes a substrate 10, a substrate 20, and a thermoelectric conversion element 30.

  The substrate 10 has a substantially square outline in plan view. The substrate 10 is made of a material having excellent heat conduction characteristics such as copper and aluminum. When the board | substrate 10 is a mere cover, the board | substrate 10 may consist of resin etc. or FPC (Flexible printed circuits) may be sufficient as it. An electrode 101 (see FIG. 2A) to be joined to the upper surface of the thermoelectric conversion element 30 is formed on the lower surface (the surface on the negative side of the Z axis) of the substrate 10. When the board | substrate 10 consists of electroconductive materials, such as copper, an insulating layer is formed in the lower surface of the board | substrate 10, and the electrode 101 is formed in the lower surface of an insulating layer. The insulating layer and the electrode 101 are formed, for example, by a process using thermocompression bonding.

  The substrate 20 has the same shape and size as the substrate 10. As will be described later, the substrate 20 has a configuration in which an insulating layer 202 is formed on the upper surface of the base plate 201 (see FIG. 2A). The base plate 201 is made of a material having excellent heat conduction characteristics such as copper and aluminum. A plurality of electrodes 203 (see FIGS. 2A and 2B) bonded to the lower surface of the thermoelectric conversion element 30 are formed on the upper surface (the surface on the Z-axis positive side) of the substrate 10. The insulating layer 202 and the electrode 203 are formed, for example, by a process using thermocompression bonding. In the state of FIG. 1A, the lower surface of the thermoelectric conversion element 30 is joined to the electrode 203 with solder.

  As will be described later, in the electrode group formed on the upper surface of the substrate 20, lead wires 203 a and 203 b to which lead wires 40 a and 40 b (see FIGS. 2A and 2B) are soldered. It is included.

  The thermoelectric conversion element 30 has a rectangular parallelepiped shape. The thermoelectric conversion element 30 is made of, for example, a semiconductor that converts heat into electric power. The thermoelectric conversion element 30 is a material (Bi2Te3 material, lead / tellurium material, silicon / germanium material) having a large figure of merit Z (= α2 / ρK) represented by the Seebeck coefficient α, the specific resistance ρ, and the thermal conductivity K. Etc.) to which a dopant is added. Two types of p-type and n-type thermoelectric conversion elements 30 are constituted by the dopant to be added. As a dopant for configuring the p-type thermoelectric conversion element 30, for example, Sb is added. Further, for example, Se is added as a dopant for configuring the n-type thermoelectric conversion element 30. On the upper surface and the lower surface of the thermoelectric conversion element 30, electrode portions that are bonded to the above-described electrode group are formed. The thermoelectric conversion element 30 may be composed of an element that controls heat by electric power, such as a Peltier element.

  When the thermoelectric converter 1 is formed, the substrate 10 is overlaid on the substrate 20 as shown in FIG. 1A with a solder paste applied to the upper surface of the thermoelectric conversion element 30. Thereby, the electrode 101 on the lower surface of the substrate 10 comes into contact with the upper surface of the thermoelectric conversion element 30 via the solder paste. Then, the board | substrate 10 and the board | substrate 20 are poured into a reflow furnace, and the electrode 101 and the upper surface of the thermoelectric conversion element 30 are joined with solder. Thereby, as shown in FIG.1 (b), the assembly of the thermoelectric converter 1 is completed.

  In the state of FIG. 1B, all thermoelectric conversion elements 30 are connected in series by the electrode 101 on the substrate 10 side and the electrode 203 on the substrate 20 side. That is, the electrode 101 and the electrode 203 are arranged on the substrate 10 and the substrate 20 in a pattern in which all the thermoelectric conversion elements 30 can be connected in series.

  The bonding of the electrode 203 on the substrate 20 side and the lower surface of the thermoelectric conversion element 30 and the bonding of the electrode 101 on the substrate 10 side and the upper surface of the thermoelectric conversion element 30 may be performed simultaneously. In this case, after applying a solder paste to the electrode 203 on the substrate 20, the thermoelectric conversion element 30 is disposed on the electrode 203 by a jig. Thereafter, in the same manner as described above, the substrate 10 is stacked on the substrate 20, and the substrate 10 and the substrate 20 are caused to flow in a reflow furnace. As a result, the solder paste is melted and bonding of the electrode 203 and the thermoelectric conversion element 30 with solder is performed together with bonding of the electrode 101 and the thermoelectric conversion element 30 with solder. Thereby, as shown in FIG.1 (b), the assembly of the thermoelectric converter 1 is completed.

  Thus, after the assembly of the thermoelectric converter 1 is completed, electric power is supplied to the thermoelectric conversion element 30 or a lead wire for drawing electric power from the thermoelectric conversion element 30 is connected to the thermoelectric converter 1.

  FIGS. 2A and 2B are diagrams schematically showing a connecting process of the lead wires 40a and 40b. In FIG. 2A, for convenience, illustration of the substrate 10 is omitted, and only the electrode 101 on the substrate 10 side is illustrated. Further, in FIG. 2B, the illustration of the thermoelectric conversion element 30 and the electrode 101 is further omitted so that the arrangement of the electrode 203 becomes clear.

  As shown in FIGS. 2A and 2B, the substrate 20 includes a base plate 201 having excellent thermal conductivity characteristics and an insulating layer 202. A group of electrodes 203 is formed on the upper surface of the insulating layer 202. In the electrode 203 group, lead wire electrodes 203a and 203b for connecting the lead wires 40a and 40b are arranged.

  As shown in FIG. 2B, the lead wire electrodes 203a and 203b are wider than the other electrode 203 groups. In plan view, the lead wire electrode 203a has an L shape, and the lead wire electrode 203b has an inverted L shape. As shown in FIG. 2A, the thermoelectric conversion element 30 is joined to the narrow regions of the lead wire electrodes 203a and 203b.

  The lead wires 40a and 40b are joined to the wide regions of the lead wire electrodes 203a and 203b by solder, respectively. At the time of joining, as shown in FIGS. 2A and 2B, the electric wire portions of the lead wires 40a and 40b are placed on the wide regions of the lead wire electrodes 203a and 203b. In this state, solder is applied to a region indicated by a broken-line circle, and heat is applied to the solder and the lead wire electrodes 203a and 203b.

  However, as described above, the base plate 201 constituting the substrate 20 is formed of a metal material having a high thermal conductivity such as copper or aluminum in order to increase the thermoelectric conversion efficiency. Therefore, when the lead wires 40a and 40b are soldered, if heat is applied to the lead wire electrodes 203a and 203b, the heat is conducted and diffused to the base plate 201 through the insulating layer 202, and heat is applied to the joints. Is less likely to accumulate. As a result, it is difficult to properly connect the lead wires 40a and 40b to the lead wire electrodes 203a and 203b.

  Therefore, in the present embodiment, grooves are formed on the lower surface of the substrate 20 (base plate 201) so as to surround the lead wire electrodes 203a and 203b in plan view. Thereby, even if the heat applied to the lead wire electrodes 203a and 203b is conducted to the base plate 201 directly below via the insulating layer 202, it is suppressed from diffusing to the surroundings.

<Example 1>
FIG. 3 is a perspective view illustrating a formation state of the grooves 211 to 213 according to the first embodiment. FIG. 3 shows a perspective view of the vicinity of the grooves 211 to 213 viewed from the back side of the substrate 20.

  In the first embodiment, two grooves 211 and 212 parallel to the X axis and one groove 213 parallel to the Y axis are formed on the lower surface of the base plate 201. Both ends of the groove 213 are separated by a predetermined distance from the X-axis negative side ends of the two grooves 211 and 212, respectively. The depths of the grooves 211 to 213 are all the same as the thickness of the base plate 201. Therefore, the grooves 211 to 213 extend to the lower surface of the insulating layer 202. The grooves 211 to 213 are formed in the base plate 201 by, for example, an etching process.

  The lead wire electrodes 203a and 203b are disposed in a region 201a surrounded by three grooves 211 to 213 in plan view.

  FIG. 4A is a plan view of the vicinity of the grooves 211 to 213 of the base plate 201 as seen from the back side. 4B shows a structure in the vicinity of the grooves 211 to 213 in FIG. 4A at a position indicated by an alternate long and short dash line in FIG. 4A, which is parallel to the plane (YZ plane). It is sectional drawing cut | disconnected by the plane. For convenience, in FIG. 4A, the electrode 203, the lead wire electrodes 203a and 203b, and the lead wires 40a and 40b are indicated by broken lines.

  As shown in FIG. 4A, in Example 1, the electrode 203 disposed between the lead wire electrodes 203a and 203b and the lead wire electrodes 203a and 203b is surrounded by the grooves 211 to 213 in plan view. It is. As shown in FIG. 4B, the grooves 211 to 213 extend to the lower surface of the insulating layer 202.

  As described above, in the first embodiment, the three grooves 211 to 213 are formed on the lower surface of the base plate 201 so as to surround the lead wire electrodes 203a and 203b in a plan view. For this reason, as shown in FIG. 4B, the heat applied to the lead wire electrodes 203a and 203b during soldering of the lead wires 40a and 40b passes through the insulating layer 202 as shown by the dotted arrows. Even if the heat is conducted to the base plate 201 directly below, the grooves 211 to 213 serve as a barrier, and the heat is further prevented from diffusing to the surroundings. For this reason, the applied heat tends to accumulate in the lead wire electrodes 203a and 203b. Thereby, soldering of the lead wires 40a and 40b to the lead wire electrodes 203a and 203b can be performed easily and reliably.

  Moreover, in Example 1, since the grooves 211 to 213 extend to the insulating layer 202, it is possible to more reliably prevent heat from being propagated outside the grooves 211 to 213.

  In Example 1, since the lead wire electrodes 203a and 203b are surrounded by the three grooves 211 to 213 separated from each other, the inner region and the outer region of the grooves 211 to 213 of the base plate 201 are grooves. 211 is integrally connected by a portion between the end on the X-axis negative side of 211 and the groove 213, and a portion between the end on the X-axis negative side of the groove 212 and the groove 213, and the groove 211, The X-axis positive side end portion 212 and the X-axis positive side surface of the base plate 201 are integrally connected. For this reason, even if the grooves 211 to 213 extend to the insulating layer 202, the region inside the grooves 211 to 213 of the base plate 201 does not become mechanically unstable.

<Example 2>
FIG. 5 is a perspective view illustrating a formation state of the groove 221 according to the second embodiment. FIG. 5 shows a perspective view of the vicinity of the groove 221 viewed from the back side of the substrate 20.

  In the second embodiment, a continuous groove 221 is formed on the lower surface of the base plate 201. The groove 221 includes two groove portions 221a parallel to the X axis and one groove portion 221b parallel to the Y axis. The end portion on the X axis positive side of the groove portion 221a extends to the side surface on the X axis positive side of the base plate 201 and is open to the outside. The depth of the groove portion 221a and the groove portion 221b is the same as the thickness of the base plate 201. Therefore, the groove part 221 a and the groove part 221 b extend to the lower surface of the insulating layer 202. The groove 221 is formed in the base plate 201 by, for example, an etching process.

  The lead wire electrodes 203a and 203b are disposed in a region 201a surrounded by the groove 221 in plan view.

  FIG. 6A is a plan view of the vicinity of the groove 221 of the base plate 201 as viewed from the back side. For convenience, in FIG. 6A, the electrode 203, the lead wire electrodes 203a and 203b, and the lead wires 40a and 40b are indicated by broken lines.

  As shown in FIG. 6A, in Example 2, the electrode 203 disposed between the lead wire electrodes 203a and 203b and the lead wire electrodes 203a and 203b is surrounded by the groove 221 in plan view. Yes. Accordingly, also in the second embodiment, as in the first embodiment, the heat applied to the lead wire electrodes 203a and 203b during the soldering of the lead wires 40a and 40b is applied to the base plate 201 directly below the insulating layer 202. Even if it is conducted, the groove 221 becomes a barrier, and heat is further prevented from diffusing to the surroundings. For this reason, the applied heat is likely to accumulate in the lead wire electrodes 203a and 203b, and the lead wires 40a and 40b can be easily and reliably soldered to the lead wire electrodes 203a and 203b.

  In the second embodiment, as in the first embodiment, since the grooves 221 extend to the insulating layer 202, it is possible to more reliably prevent heat from being propagated to the outside of the grooves 221. Furthermore, in the second embodiment, since the lead wire electrodes 203a and 203b are completely surrounded by the series of grooves 221 without any gap, heat can be transmitted to the outside of the grooves 221 more reliably than in the first embodiment. Can be suppressed.

  In the second embodiment, the lead wire electrodes 203 a and 203 b are surrounded by a series of grooves 221, and the groove 221 extends to the insulating layer 202. These regions are completely separated, and the region inside the groove 221 is supported only by the insulating layer 202. For this reason, compared with the structure of Example 1, it is thought that the area | region inside the groove | channel 221 will be in a somewhat unstable state mechanically.

  Note that the end on the X-axis positive side of the two groove portions 221a may not extend to the side surface on the X-axis positive side of the base plate 201, and the end on the X-axis positive side of the two groove portions 221a and the base plate A part of the base plate 201 may be interposed between the side surface of the 201 on the X axis positive side. If it carries out like this, in this part, since the area | region inside the groove | channel 221 and the area | region outside the groove | channel 221 are connected, the mechanical stability of the area | region inside the groove | channel 221 can be improved that much.

<Modification 1>
In the first and second embodiments, the depths of the grooves 211 to 213 and the groove 221 are the same as the thickness of the base plate 201, and the grooves 211 to 213 and the groove 221 extend to the insulating layer 202. The depth of the groove 221 may be smaller than the thickness of the base plate 201.

  FIG. 6B is a cross-sectional view showing a configuration example (modified example 1) in which the depth of the groove 221 is smaller than the thickness of the base plate 201 in the configuration of the second embodiment. FIG. 6B is a diagram corresponding to FIG.

  Thus, since the depth of the groove 221 is smaller than the thickness of the base plate 201 in the first modification, the heat conducted to the base plate 201 directly below the lead wire electrodes 203a and 203b through the insulating layer 202 during soldering. As shown in FIG. 6B, a part of the light is diffused through a region between the groove 221 and the insulating layer 202. However, in this case as well, the groove 221 serves as a barrier and the heat is prevented from diffusing to the surroundings, so that the applied heat is likely to accumulate in the lead wire electrodes 203a and 203b. Thereby, soldering of the lead wires 40a and 40b to the lead wire electrodes 203a and 203b can be performed easily and reliably.

  As described above, when the depth of the groove 221 is made smaller than the thickness of the base plate 201, the region between the groove 221 and the outer region of the base plate 201 is divided by the region between the groove 221 and the insulating layer 202. Connected. For this reason, compared with the case of Example 2, the area | region inside the groove | channel 221 will be in a mechanically stable state.

  6B shows a configuration example in which the depth of the groove 221 is smaller than the thickness of the base plate 201 in the configuration of the second embodiment. However, in the configuration of the first embodiment, the grooves 211 to 213 are not formed. The depth may be smaller than the thickness of the base plate 201.

  The depth of the groove 221 does not necessarily have to be constant in the entire region. For example, the depth of the two groove portions 221a is smaller than the thickness of the base plate 201, and the depth of the groove portion 221b is the depth of the base plate 201. It may be the same as the thickness. Similarly, in the first embodiment, the depths of the grooves 211 to 213 are not necessarily the same. For example, the depths of the grooves 211 and 212 are smaller than the thickness of the base plate 201, and the depth of the grooves 213 is the base plate. It may be the same as the thickness of 201. Further, the depth may change in one groove.

  The depth of the groove may be set to a depth at which heat can be accumulated in the lead wire electrodes 203a and 203b so that the soldering to the lead wires 40a and 40b can be performed smoothly and reliably.

<Modification 2>
The region surrounded by the grooves 211 to 213 or the groove 221 is not limited to the region shown in the first and second embodiments.

  For example, as shown in FIG. 7A, the lead wire electrodes 203a and 203b surround a wide region where soldering is performed, that is, a region other than the narrow region where the thermoelectric conversion element 30 is joined. In addition, the grooves 211 to 213 of the first embodiment may be formed. In this case, since the region where heat is diffused during soldering can be further restricted, heat is more likely to accumulate in the wide region of the lead wire electrodes 203a and 203b where soldering is performed. Moreover, since the narrow area | region where the thermoelectric conversion element 30 is joined among the lead wire electrodes 203a and 203b is not enclosed by the grooves 211-213, the thermoelectric conversion element 30 joined to the narrow area, the base plate 201, and the like. Heat exchange between them can be performed more efficiently.

  Further, as shown in FIG. 7B, a groove 214 extending in the X-axis direction may be further formed in a region between the lead wire electrodes 203a and 203b on the lower surface of the base plate 201. In this way, when the lead wires 40a and 40b are soldered, it becomes easier to accumulate heat in the wide region of the lead wire electrode 203a and the wide region of the lead wire electrode 203b.

  Also in Example 2, as in the case of FIG. 7A, a wide region where soldering is performed, that is, a narrow region where the thermoelectric conversion element 30 is joined, of the lead wire electrodes 203a and 203b. A groove 221 may be formed so as to surround a region other than. Also in this case, a groove corresponding to the groove 214 shown in FIG. 7B may be added.

  As in the first and second embodiments, it is easier to form the grooves 211 to 213 or the groove 221 when the grooves 211 to 213 or the groove 221 are formed so as to surround the entire lead wire electrodes 203a and 203b. It becomes. Further, when the heat applied to the wide region of the lead wire electrodes 203a and 203b is conducted to the narrow region and further conducted to the base plate 201 directly below the narrow region, this heat is also absorbed by the surrounding region. Can be prevented from spreading.

<Modification 3>
In the first and second embodiments, the lead wire electrodes 203a and 203b are arranged so as to be adjacent to each other. However, depending on the arrangement pattern of the electrodes 203, the lead wire electrodes 203a and 203b may be arranged so as not to be adjacent to each other. For example, the lead wire electrode 203a may be disposed at one corner portion of the substrate 20 and the lead wire electrode 203b may be disposed at another corner portion of the substrate 20. In such a case, a groove may be formed on the lower surface of the base plate 201 so as to individually surround the lead wire electrodes 203a and 203b.

  For example, as shown in FIG. 8 (a), when the lead wire electrode 203b is disposed at a corner on the X axis positive side and the Y axis negative side, the two grooves 231 to surround the lead wire electrode 203b, 232 is formed on the lower surface of the base plate 201. As a result, the grooves 231 and 232 serve as a barrier and the heat is prevented from diffusing to the surroundings, so that the heat applied for soldering easily accumulates in the lead wire electrode 203b. Therefore, it is possible to easily and reliably solder the lead wire 40b to the lead wire electrode 203b.

  8A, the lead wire electrode 203b may be surrounded by a continuous groove. Further, a groove may be formed so as to surround only a wide region of the lead wire electrode 203b.

<Modification 4>
In the first and second embodiments, the grooves 211 to 213 or the groove 221 are formed so as to surround the lead wire electrodes 203a and 203b in a rectangular shape, but the region surrounded by the groove is not necessarily limited to a rectangular shape. For example, as shown in FIG. 8B, a groove 241 may be formed on the lower surface of the base plate 201 so that the area surrounding the lead wire electrodes 203a and 203b is semicircular. Also in this case, since the wide regions of the lead wire electrodes 203a and 203b are surrounded by the substantially grooves 241, the lead wires 40a and 40b can be soldered smoothly and reliably to the lead wire electrodes 203a and 203b.

  Further, in plan view, a groove may be formed in the lower surface of the base plate 201 so as to surround the lead electrodes 203a and 203b as well as the surrounding electrodes 203. However, in this case, the heat exchange efficiency between the thermoelectric conversion element 30 and the base plate 201 joined to the electrode 203 included in the region surrounded by the groove is slightly lowered. For this reason, it is preferable to limit the region surrounded by the groove as close as possible to the region where the lead wires 40a and 40b are joined.

  The substrate 20 may further include other layers in addition to the base plate 201 and the insulating layer 202. Further, the base plate 201 may be composed of a plurality of layers, and the insulating layer 202 may be composed of a plurality of layers. In addition, when the substrate 10 is made of a material having excellent heat conduction characteristics and one lead wire electrode is disposed on the substrate 10 side, the substrate 10 is surrounded so as to surround the lead wire electrode in plan view. A groove may be formed on the upper surface.

  In addition to the above modifications, the embodiment of the present invention can be variously modified as appropriate within the scope of the technical idea shown in the claims.

DESCRIPTION OF SYMBOLS 1 ... Thermoelectric conversion system 20 ... Board | substrate 30 ... Thermoelectric conversion element 40a, 40b ... Lead wire 101 ... Electrode group (2nd electrode group)
201 ... Base plate 202 ... Insulating layer 203 ... Electrode (first electrode group)
203a, 203b ... Lead wire electrodes 211-213 ... Groove 221 ... Groove 231 ... Groove 241 ... Groove

Claims (8)

A substrate,
A first electrode group formed on the upper surface of the substrate;
A plurality of thermoelectric conversion elements whose lower surfaces are joined to the first electrode group;
A second electrode group joined to the upper surfaces of the plurality of thermoelectric conversion elements,
A groove is formed on the lower surface of the substrate so as to surround a lead wire electrode to which a lead wire is connected in the first electrode group in a plan view.
A thermoelectric converter characterized by that. The thermoelectric converter according to claim 1,
The lead wire electrode is surrounded by the plurality of grooves,
A thermoelectric converter characterized by that. The thermoelectric converter according to claim 1,
The lead wire electrode is surrounded by a series of the grooves,
A thermoelectric converter characterized by that. The thermoelectric converter according to any one of claims 1 to 3,
The substrate includes a thermally conductive base plate and an insulating layer covering an upper surface of the base plate,
The first electrode group is formed on an upper surface of the insulating layer,
The groove is formed in the base plate.
A thermoelectric converter characterized by that. The thermoelectric converter according to claim 4, wherein
The depth of the groove is the same as the thickness of the base plate.
A thermoelectric converter characterized by that. The thermoelectric converter according to claim 4, wherein
The depth of the groove is smaller than the thickness of the base plate,
A thermoelectric converter characterized by that. The thermoelectric converter according to any one of claims 1 to 6,
The groove surrounds a region of the lead wire electrode other than the region where the thermoelectric conversion element is bonded.
A thermoelectric converter characterized by that. The thermoelectric converter according to any one of claims 1 to 6,
The groove surrounds the entire area of the lead wire electrode,
A thermoelectric converter characterized by that.

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