Thermoelectric conversion substrate, thermoelectric conversion module and method for producing thermoelectric conversion substrate

A thermoelectric conversion substrate includes an insulating substrate and at least one thermoelectric conversion unit. The insulating substrate has a first surface and a second surface at both sides of the insulating substrate in a thickness direction. The at least one thermoelectric conversion unit is incorporated in the insulating substrate. The at least one thermoelectric conversion unit includes a first thermoelectric member, a second thermoelectric member, and a first electrode disposed on the first surface of the insulating substrate. The first thermoelectric member includes a first tubular member having insulation property and a first semiconductor filled in the first tubular member. The second thermoelectric member includes a second tubular member having insulation property and a second semiconductor filled in the second tubular member. The second semiconductor has carriers different from carriers of the first semiconductor. The first electrode electrically connects the first semiconductor of the first thermoelectric member to the second semiconductor of the second thermoelectric member.

BACKGROUND

1. Technical Field

The present disclosure generally relates to a thermoelectric conversion substrate, a thermoelectric conversion module, and a method for producing a thermoelectric conversion substrate and, more particularly, to a thermoelectric conversion substrate using a Peltier element, a thermoelectric conversion module, and a method for producing a thermoelectric conversion substrate.

2. Description of the Related Art

Conventionally, for example, Unexamined Japanese Patent Publication No. 2014-7408 has proposed a production method as a method for producing a thermoelectric conversion apparatus. First, this production method prepares an insulating base material. This insulating base material includes a thermoplastic resin. A plurality of first and second via holes extend through the insulating base material in the thickness direction. The first and second via holes are respectively filled with first and second conductive pastes. In this case, the first conductive paste is obtained by forming an alloy powder with a plurality of metal atoms maintaining a predetermined crystal structure into a paste by adding an organic solvent. And the second conductive paste is obtained by forming a powder of a metal of a type different from the above alloy powder into a paste by adding an organic solvent.

An upper surface protective member and a lower surface protective member are respectively disposed on an upper surface and a lower surface of the insulating base material to form a multilayer structure. This multilayer structure has an air gap inside thereof. In this case, the upper surface protective member has an upper surface pattern that comes into contact with predetermined first and second conductive pastes, and the lower surface protective member has a lower surface pattern that comes into contact with the predetermined first and second conductive patterns.

Next, the multilayer structure is then pressurized in a stacking direction while being heated so as to pour the thermoplastic resin into the air gap, and the first and second conductive pastes are solid-phase sintered into first and second interlayer connecting members. At the same time, the first and second interlayer connecting members are electrically connected to the upper surface pattern and the lower surface pattern, respectively. In this manner, a thermoelectric conversion apparatus is produced.

SUMMARY

A thermoelectric conversion substrate according to the present disclosure includes an insulating substrate and at least one thermoelectric conversion unit. The insulating substrate has a first surface and a second surface at both sides of the insulating substrate in a thickness direction. The at least one thermoelectric conversion unit is incorporated in the insulating substrate. The at least one thermoelectric conversion unit includes a first thermoelectric member, a second thermoelectric member, and a first electrode disposed on the first surface of the insulating substrate. The first thermoelectric member includes a first tubular member having insulation property and a first semiconductor filled in the first tubular member. The second thermoelectric member includes a second tubular member having insulation property and a second semiconductor filled in the second tubular member and having carriers different from carriers of the first semiconductor. The first electrode electrically connects the first semiconductor of the first thermoelectric member to the second semiconductor of the second thermoelectric member.

The thermoelectric conversion substrate preferably further includes a second electrode disposed on the second surface of the insulating substrate. The at least one thermoelectric conversion unit includes a plurality of thermoelectric conversion units. The second electrode electrically connects the first semiconductor of the first thermoelectric member in one of the plurality of thermoelectric conversion units to the second semiconductor of the second thermoelectric member in another of the plurality of thermoelectric conversion units. A plurality of thermoelectric conversion units are electrically connected to each other in series such that the first and second semiconductors are alternately arranged.

The first surface of the insulating substrate is preferably spaced apart from each of a first distal end face of the first thermoelectric member and a second distal end face of the second thermoelectric member, the first distal end face and the second distal end face facing the first surface.

The second surface of the insulating substrate is preferably spaced apart from each of a third the distal end face of the first thermoelectric member and a fourth distal end face of the second thermoelectric member, the third distal end face and the fourth distal end face facing the second surface.

The insulating substrate has, at the first surface, a first opening portion reaching the first distal end face of the first thermoelectric member. And the insulating substrate has, at the first surface, a second opening portion reaching the second distal end face of the second thermoelectric member. An area of the first distal end face of the first thermoelectric member is preferably larger than an area of a bottom surface of the first opening portion. And an area of the second distal end face of the second thermoelectric member is preferably larger than an area of a bottom surface of the second opening portion.

The insulating substrate has, at the second surface, a third opening portion reaching the third distal end face of the first thermoelectric member. And the insulating substrate has, at the second surface, a fourth opening portion reaching the fourth distal end face of the second thermoelectric member. An area of the third distal end face of the first thermoelectric member is preferably larger than an area of a bottom surface of the third opening portion. And an area of the fourth distal end face of the second thermoelectric member is preferably larger than an area of a bottom surface of the fourth opening portion.

The insulating substrate includes a multilayer structure including a core insulating layer and a first insulating layer. The core insulating layer includes a first thermoelectric member and a second thermoelectric member. And the first insulating layer includes neither first thermoelectric member nor second thermoelectric member. In addition, the first insulating layer is located at a side in which the first surface of the insulating substrate is positioned, and the core insulating layer is located at a side in which the second surface of the insulating substrate is positioned. A thermal conductivity of the first insulating layer is greater than a thermal conductivity of the core insulating layer.

An insulating substrate includes a multilayer structure including a core insulating layer, a first insulating layer, and a second insulating layer. The core insulating layer includes a first thermoelectric member and a second thermoelectric member. The first insulating layer includes neither first thermoelectric member nor second thermoelectric member. The second insulating layer includes neither first thermoelectric member nor second thermoelectric member. In addition, the core insulating layer is located between the first insulating layer and the second insulating layer. The first insulating layer is located at a side in which the first surface of the insulating substrate is positioned. The second insulating layer is located at a side in which the second surface of the insulating substrate is positioned. A thermal conductivity of each of the first insulating layer and the second insulating layer is greater than a thermal conductivity of the core insulating layer.

A wiring layer is preferably disposed in at least one of a boundary between the core insulating layer and the first insulating layer and a boundary between the core insulating layer and the second insulating layer.

A thermoelectric conversion module according to the present disclosure includes the thermoelectric conversion substrate, an insulating film, and an electronic component. The insulating film is disposed on at least one of the first surface and the second surface of the insulating substrate of the thermoelectric conversion substrate. The electronic component is mounted to the thermoelectric conversion substrate via the insulating film.

A method for producing a thermoelectric conversion substrate according to the present disclosure includes the following steps. First step is preparing a semi-cured core substrate. Second step is forming a plurality of through holes in the semi-cured core substrate. Third step is preparing at least one first thermoelectric member and at least one second thermoelectric member, and inserting the at least one first thermoelectric member and the at least one second thermoelectric member into the plurality of through holes of the semi-cured core substrate. The at least one first thermoelectric member includes a first tubular member filled with a first semiconductor. The at least one second thermoelectric member includes a second tubular member filled with a second semiconductor. The second semiconductor has carriers different from carriers of the first semiconductor. Fourth step is forming an insulating substrate by stacking respective metal foils on both surfaces of the semi-cured core substrate and then hot-pressing the semi-cured core substrate along with the metal foils. The insulating substrate has a first surface and a second surface at both sides of the insulating substrate in a thickness direction. Fifth step is removing a part of the metal foils at a position corresponding to each of locations of the at least one first thermoelectric member and the at least one second thermoelectric member. Sixth step is exposing a distal end face of each of the at least one first thermoelectric member and the at least one second thermoelectric member by removing a part of the insulating substrate at which the part of the metal foils have been removed. Seventh step is providing plating, ranging from each of the distal end face of the at least one first thermoelectric member and the distal end face of the at least one second thermoelectric member to one of the metal foils. Eighth step is forming a first electrode that electrically connects the at least one first thermoelectric member to the at least one second thermoelectric member by partially removing the one of the metal foils at the first surface of the insulating substrate.

The at least one first thermoelectric member includes a plurality of first thermoelectric members. And the at least one second thermoelectric member includes a plurality of second thermoelectric members. This method preferably further includes forming a second electrode by partially removing one of the metal foils at the second surface of the insulating substrate. The second electrode electrically connects one of the plurality of first thermoelectric members to one of the plurality of second thermoelectric members, which are not electrically to each other by the first electrode.

A method for producing a thermoelectric conversion substrate according to the present disclosure includes the following steps. First step is preparing a first metal foil. Second step is preparing at least one first thermoelectric member and at least one second thermoelectric member, and soldering the at least one first thermoelectric member and the at least one second thermoelectric member to the first metal foil, respectively. The at least one first thermoelectric member includes a first tubular member filled with a first semiconductor. And the at least one second thermoelectric member includes a second tubular member filled with a second semiconductor. The second semiconductor has carriers different from carriers of the first semiconductor. Third step is preparing a semi-cured core substrate having opening portions and stacking the semi-cured core substrate on the first metal foil so as to accommodate the at least one first thermoelectric member and the at least one second thermoelectric member in the opening portions. Fourth step is forming an insulating substrate from a cured product of the semi-cured core substrate by stacking a second metal foil on the semi-cured core substrate so as to close the opening portions and then hot-pressing the semi-cured core substrate along with the second metal foil. Fifth step is removing a part of the second metal foil at a position corresponding to each of locations of the at least one first thermoelectric member and the at least one second thermoelectric member. Sixth step is exposing a distal end face of each of the at least one first thermoelectric member and the at least one second thermoelectric member by removing a part of the insulating substrate at which the part of the second metal foil has been removed. Seventh step is providing plating, ranging from each of the distal end face of the at least one first thermoelectric member and the distal end face of the at least one second thermoelectric member to the second metal foil. Eighth step is forming a first electrode that electrically connects the at least one first thermoelectric member to the at least one second thermoelectric member by partially removing the second metal foil on the insulating substrate.

The at least one first thermoelectric member includes a plurality of first thermoelectric members. And the at least one second thermoelectric member includes a plurality of second thermoelectric members. This method preferably further includes forming a second electrode by partially removing the first metal foil on the insulating substrate. The second electrode electrically connects one of the plurality of first thermoelectric members to one of the plurality of second thermoelectric members, which differ from one of the plurality of first thermoelectric members and one of the plurality of second thermoelectric members electrically connected to each other by the first electrode.

A method for producing a thermoelectric conversion substrate according to the present disclosure includes the following steps. First step is preparing a base substrate including at least one second electrode. Second step is preparing at least one first thermoelectric member and at least one second thermoelectric member, and soldering the at least one first thermoelectric member and the at least one second thermoelectric member to the second electrode, respectively. The at least one first thermoelectric member includes a first tubular member filled with a first semiconductor. The at least one second thermoelectric member includes a second tubular member filled with a second semiconductor. The second semiconductor has carriers different from carriers of the first semiconductor. Third step is preparing a semi-cured core substrate having opening portions and stacking the semi-cured core substrate on the base substrate so as to accommodate the at least one first thermoelectric member and the at least one second thermoelectric member in the opening portions. Fourth step is forming an insulating substrate from a cured product of the semi-cured core substrate by stacking a metal foil on the semi-cured core substrate so as to close the opening portions and then hot-pressing the semi-cured core substrate along with the metal foil. Fifth step is removing a part of the metal foil at a position corresponding to each of locations of the at least one first thermoelectric member and the at least one second thermoelectric member. Sixth step is exposing a distal end face of each of the at least one first thermoelectric member and the at least one second thermoelectric member by removing a part of the insulating substrate at which the part of the metal foil has been removed. Seventh step is providing plating, ranging from each of the distal end face of the at least one first thermoelectric member and the distal end face of the at least one second thermoelectric member to the metal foil. Eighth step is forming a first electrode that electrically connects the at least one first thermoelectric member to the at least one second thermoelectric member by partially removing the metal foil on the insulating substrate.

A method for producing a thermoelectric conversion substrate according to the present disclosure includes the following steps. First step is preparing a first metal foil. Second step is preparing at least one first thermoelectric member and at least one second thermoelectric member, and soldering the at least one first thermoelectric member and the at least one second thermoelectric member to the first metal foil, respectively. The at least one first thermoelectric member includes a first tubular member filled with a first semiconductor. The at least one second thermoelectric member includes a second tubular member filled with a second semiconductor. The second semiconductor has carriers different from carriers of the first semiconductor. Third step is preparing a cured or semi-cured core substrate having opening portions and stacking the cured or semi-cured core substrate on the first metal foil so as to accommodate the at least one first thermoelectric member and the at least one second thermoelectric member in the opening portions. Fourth step is pouring a resin into the opening portions to fill the opening portions and stacking a second metal foil on the cured or semi-cured core substrate so as to close the opening portions and then hot-pressing the cured or semi-cured core substrate along with the second metal foil and the resin to form an insulating substrate from the cured core substrate or a cured product of the semi-cured core substrate with a cured product of the resin. Fifth step is removing a part of the second metal foil at a position corresponding to each of locations of the at least one first thermoelectric member and the at least one second thermoelectric member. Sixth step is exposing a distal end face of each of the at least one first thermoelectric member and the at least one second thermoelectric member by removing a part of the insulating substrate at which the part of the second metal foil has been removed. Seventh step is providing plating, ranging from each of the distal end face of the at least one first thermoelectric member and the distal end face of the at least one second thermoelectric member to the second metal foil. Eighth step is forming a first electrode that electrically connects the at least one first thermoelectric member to the at least one second thermoelectric member by partially removing the second metal foil on the insulating substrate.

According to the present disclosure, it is possible to improve quality stability of a thermoelectric conversion unit and suppress damage to the thermoelectric conversion unit.

DETAILED DESCRIPTION OF EMBODIMENT

Prior to describing an exemplary embodiment of the present disclosure, problems found in conventional techniques will be briefly described. In the thermoelectric conversion apparatus disclosed in Unexamined Japanese Patent Publication No. 2014-7408, because the first and second interlayer connecting members are obtained simply by solid-phase sintering the first and second conductive pastes, the first and second interlayer connecting members tend to be damaged when a load is applied on the insulating substrate in the thickness direction.

Whether or not the first and second interlayer connecting members normally function as a thermoelectric conversion unit needs to be checked after the production of a thermoelectric conversion apparatus. In addition, when there are many first and second interlayer connecting members, it is also difficult to specify which interlayer connecting member is defective.

The present disclosure has been made in consideration of the above points, and provides a thermoelectric conversion substrate, a thermoelectric conversion module, and a method for producing a thermoelectric conversion substrate, which can implement stability for high quality of a thermoelectric conversion unit and suppress damage to the thermoelectric conversion unit.

An exemplary embodiment of the present disclosure will be described below.

FIG. 1Ashows an example of thermoelectric conversion substrate1. Thermoelectric conversion substrate1includes insulating substrate2, and thermoelectric conversion unit3. Thermoelectric conversion substrate1is an example including one thermoelectric conversion unit3. However, an example including a plurality of thermoelectric conversion units3will be described later with reference toFIG. 1B.

Insulating substrate2has first surface21and second surface22on its both sides in a thickness direction. A double-headed arrow inFIG. 1Aindicates the thickness direction. First surface21and second surface22are both surfaces of insulating substrate2. Either one of the surfaces may be an upper surface or lower surface. Insulating substrate2is not specifically limited as long as it has an insulation property. For example, insulating substrate2is a substrate obtained by curing a thermosetting resin composition impregnated in a reinforcing material. A specific example of insulating substrate2is a glass epoxy substrate. The glass epoxy substrate is a substrate obtained by curing a thermosetting resin composition containing epoxy resin in glass cloth as a reinforcing material. A thermosetting resin composition may contain a filler.

Thermoelectric conversion unit3is incorporated in insulating substrate2. Thermoelectric conversion unit3is an element that is a kind of thermoelectric element and converts heat into power. A Peltier element is a specific example of thermoelectric conversion unit3.

Thermoelectric conversion unit3includes first thermoelectric member31, second thermoelectric member32, and first electrode41. First thermoelectric member31includes insulating first tubular member301having an insulation property and first semiconductor311, as shown inFIG. 2A.

First tubular member301is not specifically limited as long as it is a tubular member having openings in its both ends and has an insulation property. For example, first tubular member301has a length between 0.4 mm and 2.0 mm (inclusive), an outer diameter between 0.4 mm and 2.0 mm (inclusive), an inner diameter between 0.39 mm and 1.88 mm (inclusive), and a thickness between 0.005 mm and 0.1 mm (inclusive). First tubular member301preferably has a smaller thermal expansion coefficient than insulating substrate2. A specific example of first tubular member301is a glass tube. First semiconductor311is filled in first tubular member301. A specific example of first semiconductor311is a p-type semiconductor. The p-type semiconductor is obtained by, for example, adding a small amount of selenium as an impurity in a bismuth telluride based compound.

It is preferable that distal end portion341be provided so as to close one end of first tubular member301filled with first semiconductor311, and distal end portion351be provided so as to close the other end. Distal end portion341faces first surface21of insulating substrate2, and distal end portion351faces second surface22of insulating substrate2. Distal end portion341includes a barrier film directly closing an opening of one end of first tubular member301and a joining layer provided on the barrier film. The barrier film further includes a Ti layer and an Ni layer provided on the Ti layer. In the barrier film, the Ti layer is in contact with first semiconductor311while directly closing the opening of one end of first tubular member301, and the Ni layer is in contact with the joining layer. The joining layer is formed from, for example, a joining material including Sn, Au, Ag, and Cu. For example, the Ti layer has a thickness between 0.02 μm and 0.3 μm (inclusive), the Ni layer has a thickness between 0.5 μm and 10 μm (inclusive), and the joining layer has a thickness between 0.1 μm and 100 μm (inclusive). Distal end portion351is formed in the same manner as distal end portion341.

Second tubular member302is not specifically limited as long as it is a tubular member having openings in its both ends and has an insulation property. Second tubular member302preferably has a smaller thermal expansion coefficient than insulating substrate2. The size and material of second tubular member302are preferably the same as those of first tubular member301.

Second semiconductor312is filled in second tubular member302. Second semiconductor312has carriers different from carriers of first semiconductor311. If the carriers of first semiconductor311are holes, the carriers of second semiconductor312are electrons. The carriers for each of first semiconductor311and second semiconductor312can also be changed to be opposite. A specific example of second semiconductor312is an n-type semiconductor. The n-type semiconductor is obtained by, for example, adding a small amount of antimony or indium as an impurity in a bismuth telluride based compound.

It is preferable that distal end portion342be provided so as to close one end of second tubular member302filled with second semiconductor312, and distal end portion352be provided so as to close the other end. Distal end portion342faces first surface21of insulating substrate2, and distal end portion352faces second surface22of insulating substrate2. Distal end portions342and352of second thermoelectric member32are formed in the same manner as distal end portions341and351of first thermoelectric member31.

As shown inFIG. 1A, first electrode41is provided on first surface21of insulating substrate2. It is not limited but a specific example of the material of first electrode41is copper. First electrode41electrically connects first semiconductor311of first thermoelectric member31to second semiconductor312of second thermoelectric member32. Note that if first thermoelectric member31is provided with distal end portion341, first electrode41is electrically connected to first semiconductor311via distal end portion341. Likewise, if second thermoelectric member32is provided with distal end portion342, first electrode41is electrically connected to second semiconductor312via distal end portion342.

Second electrodes412and422for power supply connection are provided on second surface22of insulating substrate2. Second electrode412is electrically connected to first semiconductor311of first thermoelectric member31. If first thermoelectric member31is provided with distal end portion351, second electrode412is electrically connected to first semiconductor311via distal end portion351. Second electrode422is electrically connected to second semiconductor312of second thermoelectric member32. If second thermoelectric member32is provided with distal end portion352, second electrode422is electrically connected to second semiconductor312via distal end portion352. Second electrodes412and422are electrically insulated from each other.

Connecting a DC power supply to second electrodes412and422and applying a voltage between the second electrodes412and422to make a DC current flow can transfer heat from one surface of insulating substrate2to the other surface due to a Peltier effect. If, for example, first semiconductor311is a p-type semiconductor and second semiconductor312is an n-type semiconductor, making a DC current flow from second semiconductor312to first semiconductor311can transfer heat from first surface21of insulating substrate2to second surface22. When a polarity of the DC power supply is reversed to change the direction of a DC current, the transferring direction of heat is reversed. This makes it possible to freely switch between cooling and heating. Note that, contrary to the Peltier effect, a temperature difference may be provided between first surface21and second surface22of insulating substrate2to cause a potential difference due to a Seebeck effect, thereby extracting power.

In thermoelectric conversion substrate1shown inFIG. 1A, since first semiconductor311and second semiconductor312are respectively protected by first tubular member301and second tubular member302, damage to thermoelectric conversion unit3can be suppressed even when a load is applied on insulating substrate2. For example, a direction of loading on insulating substrate2is the thickness direction. However, the direction of loading is not limited to this.

As described above, heat transfers inside insulating substrate2, and insulating substrate2slightly thermally expands as the heat transfers. Even if the influence of this thermal expansion reaches first thermoelectric member31and second thermoelectric member32of thermoelectric conversion unit3, damage to thermoelectric conversion unit3can be suppressed because first semiconductor311and second semiconductor312are respectively protected by first tubular member301and second tubular member302. This configuration is especially effective when first tubular member301and second tubular member302each have a smaller thermal expansion coefficient than insulating substrate2.

First surface21of insulating substrate2is preferably spaced apart from distal end face321of first thermoelectric member31which faces first surface21in the thickness direction of insulating substrate2. Proving a level difference between first surface21and distal end face321in this manner makes it difficult for even a load on first surface21in the thickness direction to be directly exerted on distal end face321. This can further suppress damage to first thermoelectric member31. Likewise, first surface21of insulating substrate2is spaced apart from distal end face322of second thermoelectric member32which faces first surface21in the thickness direction of insulating substrate2. In this case as well, providing a level difference between first surface21and distal end face322makes it difficult for even a load on first surface21in the thickness direction to be directly exerted on distal end face322. This can further suppress damage to second thermoelectric member32. For example, the above level difference, i.e., a distance between first surface21and each of distal end faces321and322is between 25 μm and 200 μm (inclusive).

Second surface22of insulating substrate2is preferably spaced apart from distal end face331of first thermoelectric member31which faces second surface22in the thickness direction of insulating substrate2. Proving a level difference between second surface22and distal end face331in this manner makes it difficult for even a load on second surface22in the thickness direction to be directly exerted on distal end face331. This can further suppress damage to first thermoelectric member31. Likewise, second surface22of insulating substrate2is spaced apart from distal end face332of second thermoelectric member32which faces second surface22in the thickness direction of insulating substrate2. In this case as well, providing a level difference between second surface22and distal end face332makes it difficult for even a load on second surface22in the thickness direction to be directly exerted on distal end face332. This can further suppress damage to second thermoelectric member32. For example, the above level difference, i.e., a distance between second surface22and each of distal end faces331and332is between 25 μm and 200 μm (inclusive).

First opening portion201is preferably provided in first surface21of insulating substrate2. A filled via can be obtained by filling first opening portion201with a conductor such as a plate when forming first electrode41in first opening portion201. First opening portion201is provided so as to extend from first surface21of insulating substrate2to distal end face321of first thermoelectric member31which faces first surface21. A bottom surface of first opening portion201is preferably part of distal end face321of first thermoelectric member31. That is, as shown inFIG. 3, area S321of distal end face321of first thermoelectric member31which faces first surface21is larger than area S2001of the bottom surface of first opening portion201. This can suppress positional shift of first thermoelectric member31to first surface21. Although not shown, area S2001of the bottom surface of first opening portion201may be equal to area S2101of first surface21of first opening portion201. In this case, a specific example of a shape of first opening portion201is a cylindrical shape. Cylindrical first opening portion201has a constant inner diameter in a depth direction. The depth direction is the same as the thickness direction of insulating substrate2. As shown inFIG. 3, area S2001of the bottom surface of first opening portion201is preferably smaller than area S2101. In this case, a specific example of a shape of first opening portion201is a bowl shape. Bowl-shaped first opening portion201gradually increases in inner diameter from the bottom surface to first surface21in the depth direction. Forming first electrode41in bowl-shaped first opening portion201makes it difficult for first electrode41to break.

Second opening portion202is preferably provided in first surface21of insulating substrate2. A filled via can be obtained by filling second opening portion202with a conductor such as a plate when forming first electrode41in second opening portion202. Second opening portion202is provided so as to extend from first surface21of insulating substrate2to distal end face322of second thermoelectric member32which faces first surface21. A bottom surface of second opening portion202is preferably part of distal end face322of second thermoelectric member32. That is, as shown inFIG. 3, area S322of distal end face322of second thermoelectric member32which faces first surface21is larger than area S2002of a bottom surface of second opening portion202. This can suppress positional shift of second thermoelectric member32to first surface21. Although not shown, area S2002of the bottom surface of second opening portion202may be equal to area S2102of first surface21of second opening portion202. In this case, a specific example of a shape of second opening portion202is a cylindrical shape. Cylindrical second opening portion202has a constant inner diameter in a depth direction. As shown inFIG. 3, area S2002of the bottom surface of second opening portion202is preferably smaller than area S2102. In this case, a specific example of a shape of second opening portion202is a bowl shape. Bowl-shaped second opening portion202gradually increases in inner diameter from the bottom surface to first surface21in the depth direction. Forming first electrode41in bowl-shaped second opening portion202makes it difficult for first electrode41to break.

Third opening portion211is preferably provided in second surface22of insulating substrate2. A filled via can be obtained by filling third opening portion211with a conductor such as a plate when forming second electrode412for power supply connection in third opening portion211. Second electrode412for power supply connection may be replaced by second electrode42(to be described later) that electrically connects adjacent thermoelectric conversion units3. Third opening portion211is provided so as to extend from second surface22of insulating substrate2to distal end face331of first thermoelectric member31which faces second surface22. A bottom surface of third opening portion211is preferably part of distal end face331of first thermoelectric member31. That is, as shown inFIG. 3, area S331of distal end face331of first thermoelectric member31which faces second surface22is larger than area S2011of the bottom surface of third opening portion211. This can suppress positional shift of first thermoelectric member31to second surface22. Although not shown, area S2011of the bottom surface of third opening portion211may be equal to area S2111of second surface22of third opening portion211. In this case, a specific example of a shape of third opening portion211is a cylindrical shape. Cylindrical third opening portion211has a constant inner diameter in a depth direction. As shown inFIG. 3, area S2011of the bottom surface of third opening portion211is preferably smaller than area S2111. In this case, a specific example of a shape of third opening portion211is a bowl shape. Bowl-shaped third opening portion211gradually increases in inner diameter from the bottom surface to second surface22in the depth direction. Forming second electrodes412and42in bowl-shaped third opening portion211makes it difficult for second electrodes412and42to break.

Fourth opening portion212is preferably provided in second surface22of insulating substrate2. A filled via can be obtained by filling fourth opening portion212with a conductor such as a plate when forming second electrode422for power supply connection in fourth opening portion212. Second electrode422for power supply connection may be replaced by second electrode42(to be described later) that electrically connects adjacent thermoelectric conversion units3. Fourth opening portion212is provided so as to extend from second surface22of insulating substrate2to distal end face332of second thermoelectric member32which faces second surface22. A bottom surface of fourth opening portion212is preferably part of distal end face332of second thermoelectric member32. That is, as shown inFIG. 3, area S332of distal end face332of second thermoelectric member32which faces second surface22is larger than area S2012of the bottom surface of fourth opening portion212. This can suppress positional shift of second thermoelectric member32to second surface22. Although not shown, area S2012of the bottom surface of fourth opening portion212may be equal to area S2112of second surface22of fourth opening portion212. In this case, a specific example of a shape of fourth opening portion212is a cylindrical shape. Cylindrical fourth opening portion212has a constant inner diameter in a depth direction. As shown inFIG. 3, area S2012of the bottom surface of fourth opening portion212is preferably smaller than area S2112. In this case, a specific example of a shape of fourth opening portion212is a bowl shape. Bowl-shaped fourth opening portion212gradually increases in inner diameter from the bottom surface to second surface22in the depth direction. Forming second electrodes422or42in bowl-shaped fourth opening portion212makes it difficult for second electrodes422or42to break.

As shown inFIG. 1A, insulating substrate2is preferably formed from multilayer structure53constituted by core insulating layer50, first insulating layer51, and second insulating layer52. When insulating substrate2is constituted by a plurality of layers, a thermal conductivity of each layer can be changed in accordance with a purpose of use of thermoelectric conversion substrate1. Each layer is not specifically limited as long as it has an insulating property. For example, each layer is a layer obtained by curing a thermosetting resin composition impregnated in a reinforcing material. Impregnating the thermosetting resin composition with a filler in advance can change the thermal conductivity of each layer. Specific examples of a filler are alumina, silica, magnesium hydroxide, and aluminum hydroxide.

Core insulating layer50includes first thermoelectric member31and second thermoelectric member32. A thickness of core insulating layer50is greater than a length of each of first thermoelectric member31and second thermoelectric member32. Core insulating layer50is located between first insulating layer51and second insulating layer52. Core insulating layer50has a thermal conductivity between 0.5 W/m·K and 0.8 W/m·K (inclusive). However, this is not limited.

First insulating layer51includes neither first thermoelectric member31nor second thermoelectric member32. First insulating layer51has a thickness less than or equal to 200 μm. First insulating layer51is located facing first surface21of insulating substrate2. First insulating layer51has a thermal conductivity between 1.1 W/m·K and 1.6 W/m·K (inclusive). However, this is not limited.

Second insulating layer52includes neither first thermoelectric member31nor second thermoelectric member32. Second insulating layer52has a thickness less than or equal to 200 μm. Second insulating layer52is located facing second surface22of insulating substrate2. Second insulating layer52has a thermal conductivity between, for example, 1.1 W/m·K and 1.6 W/m·K. However, this is not limited.

Core insulating layer50preferably has a higher thermal conductivity than first insulating layer51and second insulating layer52. An object to be cooled (e.g., electronic component7to be described later) is located on insulating substrate2facing first surface21or facing second surface22. Assume that the object to be cooled is disposed on insulating substrate2facing first surface21, and a temperature of the object is not high. In this case, when a thermal conductivity of first insulating layer51is high, first insulating layer51can be naturally cooled by ensuring a heat dissipation path as a whole without energizing thermoelectric conversion unit3for forced cooling. Assume that the temperature of the object to be cooled is high. In this case, if the thermal conductivity of core insulating layer50is low, a temperature difference can be ensured between a portion facing first surface21and a portion facing second surface22in insulating substrate2. Hence, forced cooling of the object can be performed by energizing thermoelectric conversion unit3to make thermoelectric conversion unit3exert its original function.

Core insulating layer50may have a lower thermal conductivity than thermoelectric conversion unit3(having a thermal conductivity of, for example, less than 1.0 W/m·K), and first insulating layer51and second insulating layer52each may have a lower thermal conductivity than core insulating layer50. In this case, since heat of the object to be cooled concentrates on thermoelectric conversion unit3, the cooling effect can be enhanced by energizing thermoelectric conversion unit3to perform forced cooling.

In this case, when first insulating layer51has a higher thermal conductivity than thermoelectric conversion unit3while the object to be cooled is disposed on insulating substrate2facing first surface21, first insulating layer51diffuses the heat of the object. This may not sufficiently enhance the cooling effect.

Consequently, thermal conductivities of core insulating layer50, first insulating layer51, and second insulating layer52are preferably selected in consideration of the degree of possibility of forced cooling of the object to be cooled.

As shown inFIG. 4A, wiring layer43is interposed at least between core insulating layer50and first insulating layer51or between core insulating layer50and second insulating layer52. Wiring layer43can be used for a purpose other than the purpose of energizing thermoelectric conversion unit3. For example, specific examples of wiring layer43include a signal layer, a power supply layer, and a ground layer. Incorporating wiring layer43inside insulating substrate2in this manner can implement multiple functions and high density of thermoelectric conversion substrate1.

The above substrate is an example of thermoelectric conversion substrate1including one thermoelectric conversion unit3. An example of thermoelectric conversion substrate1including a plurality of thermoelectric conversion units3will be described next.

FIG. 1Bshows an example of thermoelectric conversion substrate1including a plurality of thermoelectric conversion units3. Thermoelectric conversion substrate1includes a plurality of thermoelectric conversion units3. Each of the plurality of thermoelectric conversion units3is the same as the thermoelectric conversion unit described above. Thermoelectric conversion substrate1further includes at least one second electrode42.

Second electrode42is provided on second surface22of insulating substrate2. It is not limited but a specific example of a material of second electrode42is copper. Second electrode42electrically connects first semiconductor311of first thermoelectric member31of one thermoelectric conversion unit3(thermoelectric conversion unit3on a right side inFIG. 1B) to second semiconductor312of second thermoelectric member32of another thermoelectric conversion unit3(thermoelectric conversion unit3on a left side inFIG. 1B). When distal end portion351is provided on first thermoelectric member31, second electrode42is electrically connected to first semiconductor311via distal end portion351. Likewise, when distal end portion352is provided on second thermoelectric member32, second electrode42is electrically connected to second semiconductor312via distal end portion352. In this manner, second electrode42electrically connects two different thermoelectric conversion units3. The same applies to a thermoelectric conversion substrate including three or more thermoelectric conversion units3. A plurality of thermoelectric conversion units3are electrically connected in series so as to alternately arrange first semiconductor311and second semiconductor312. This indicates that a total number of second electrodes42is smaller by one than a total number of thermoelectric conversion units3.

Second electrodes412and422for power supply connection are preferably provided on second surface22of insulating substrate2. Second electrode412is electrically connected to first semiconductor311of first thermoelectric member31of one thermoelectric conversion unit3(thermoelectric conversion unit3on the left side inFIG. 1B), of the plurality of thermoelectric conversion units3connected in series, which is located on one end. If first thermoelectric member31is provided with distal end portion351, second electrode412is electrically connected to first semiconductor311via distal end portion351. Second electrode422is electrically connected to second semiconductor312of second thermoelectric member32of one thermoelectric conversion unit3(thermoelectric conversion unit3on the right side inFIG. 1B), of the plurality of thermoelectric conversion units3connected in series, which is located on the other end. If second thermoelectric member32is provided with distal end portion352, second electrode422is electrically connected to second semiconductor312via distal end portion352.

Connecting a DC power supply to second electrodes412and422and applying a voltage between the second electrodes412and422to make a current flow can transfer heat from one surface of insulating substrate2to the other surface due to the Peltier effect. If, for example, first semiconductor311is a p-type semiconductor and second semiconductor312is an n-type semiconductor, making a DC current flow from second semiconductor312to first semiconductor311can transfer heat from first surface21of insulating substrate2to second surface22. When a polarity of the DC power supply is reversed to change the direction of a DC current, the transferring direction of heat is reversed. This makes it possible to freely switch between cooling and heating. Although not shown, a thermistor that is a sensor for measuring a temperature may be used such that when a temperature of the object to be cooled becomes more than or equal to a predetermined temperature, thermoelectric conversion unit3is energized, whereas when the temperature is less than the predetermined temperature, thermoelectric conversion unit3is not energized.

In thermoelectric conversion substrate1shown inFIG. 1B, since first semiconductor311and second semiconductor312are respectively protected by first tubular member301and second tubular member302, damage to thermoelectric conversion unit3can be suppressed even upon loading on insulating substrate2. For example, a direction of loading on insulating substrate2is the thickness direction. However, the direction of loading is not limited to this.

As described above, heat transfers inside insulating substrate2, and insulating substrate2slightly thermally expands as the heat transfers. Even if the influence of this thermal expansion reaches first thermoelectric member31and second thermoelectric member32of thermoelectric conversion unit3, damage to thermoelectric conversion unit3can be suppressed because first semiconductor311and second semiconductor312are respectively protected by first tubular member301and second tubular member302. This configuration is especially effective when first tubular member301and second tubular member302each have a smaller thermal expansion coefficient than insulating substrate2.

FIG. 5Ashows another example of thermoelectric conversion substrate1. Thermoelectric conversion substrate1is the same as thermoelectric conversion substrate1shown inFIG. 1Ain that it includes one thermoelectric conversion unit3. Accordingly, a description of commonalities will be omitted, and only differences will be described.

Thermoelectric conversion substrate1shown inFIG. 5Ahas nothing corresponding to second insulating layer52, and second surface22of insulating substrate2has nothing corresponding to third opening portion211and fourth opening portion212.

Insulating substrate2is preferably formed from multilayer structure53constituted by core insulating layer50and first insulating layer51. When insulating substrate2is constituted by a plurality of layers, a thermal conductivity of each layer can be changed in accordance with a purpose of use of thermoelectric conversion substrate1. Each layer is not specifically limited as long as it has an insulating property. For example, each layer is a layer obtained by curing a thermosetting resin composition impregnated in a reinforcing material. Impregnating the thermosetting resin composition with a filler in advance can change the thermal conductivity of each layer. Specific examples of a filler are alumina, silica, magnesium hydroxide, and aluminum hydroxide.

Core insulating layer50includes first thermoelectric member31and second thermoelectric member32. A thickness of core insulating layer50is greater than a length of each of first thermoelectric member31and second thermoelectric member32. Core insulating layer50is located on insulating substrate2facing second surface22. Core insulating layer50has a thermal conductivity between 0.5 W/m·K and 0.8 W/m·K (inclusive). However, this is not limited.

First insulating layer51includes neither first thermoelectric member31nor second thermoelectric member32. First insulating layer51has a thickness less than or equal to 200 μm. First insulating layer51is located facing first surface21of insulating substrate2. First insulating layer51has a thermal conductivity between 1.1 W/m·K and 1.6 W/m·K (inclusive). However, this is not limited.

First insulating layer51preferably has a higher thermal conductivity than core insulating layer50. An object to be cooled (e.g., electronic component7to be described later) is located on insulating substrate2facing first surface21or facing second surface22. Assume that the object to be cooled is disposed on insulating substrate2facing first surface21, and a temperature of the object is not high. In this case, when a thermal conductivity of first insulating layer51is high, first insulating layer51can be naturally cooled by ensuring a heat dissipation path as a whole without energizing thermoelectric conversion unit3for forced cooling. Assume that the temperature of the object to be cooled is high. In this case, if the thermal conductivity of core insulating layer50is low, a temperature difference can be ensured between a portion facing first surface21and a portion facing second surface22of insulating substrate2. Hence, forced cooling of the object can be performed by energizing thermoelectric conversion unit3to make thermoelectric conversion unit3exert its original function.

Core insulating layer50may have a lower thermal conductivity (e.g., less than 1.0 W/m·K) than thermoelectric conversion unit3, and first insulating layer51may have a lower thermal conductivity than core insulating layer50. In this case, since heat of the object to be cooled concentrates on thermoelectric conversion unit3, the cooling effect can be enhanced by energizing thermoelectric conversion unit3to perform forced cooling.

In this case, when first insulating layer51has a higher thermal conductivity than thermoelectric conversion unit3while the object to be cooled is disposed on insulating substrate2facing first surface21, first insulating layer51diffuses the heat of the object. This may not sufficiently enhance the cooling effect.

Consequently, thermal conductivities of core insulating layer50and first insulating layer51are preferably selected in consideration of the degree of possibility of forced cooling of the object to be cooled.

Although not shown, a wiring layer may be interposed between core insulating layer50and first insulating layer51. The wiring layer can be used for a purpose other than the purpose of energizing thermoelectric conversion unit3. For example, specific examples of the wiring layer include a signal layer, a power supply layer, and a ground layer. Incorporating the wiring layer inside insulating substrate2in this manner can implement multiple functions and high density of thermoelectric conversion substrate1.

The above substrate is another example of thermoelectric conversion substrate1including one thermoelectric conversion unit3.FIG. 5Bshows thermoelectric conversion substrate1including a plurality of thermoelectric conversion units3. This thermoelectric conversion substrate1is common to thermoelectric conversion substrate1shown inFIG. 1Bexcept for the above differences, and hence a description will be omitted.

Thermoelectric conversion module10shown inFIG. 6Aincludes thermoelectric conversion substrate1shown inFIG. 1A. Thermoelectric conversion module10shown inFIG. 6Bincludes thermoelectric conversion substrate1shown inFIG. 1B. Thermoelectric conversion module10shown inFIG. 7Aincludes thermoelectric conversion substrate1shown inFIG. 5A. Thermoelectric conversion module10shown inFIG. 7Bincludes thermoelectric conversion substrate1shown inFIG. 5B. Thermoelectric conversion module10shown inFIG. 6Awill be described below. Here, a description of other thermoelectric conversion modules10will be omitted. Insulating film61is provided on first surface21or second surface22of insulating substrate2of thermoelectric conversion substrate1. Although insulating film61is provided on first surface21inFIG. 6A, insulating film61may be provided on second surface22. Insulating film61is not specifically limited as long as it is a sheet having an insulation property. For example, insulating film61is a sheet obtained by curing a thermosetting resin composition impregnated in a reinforcing material. Insulating film61may be obtained by curing a thermosetting resin composition in the form of a sheet without using any reinforcing material. In addition, insulating film61may be a film obtained coating thermoelectric conversion substrate1with an uncured resin material and then curing the resin like a solder resist.

Electronic component7is mounted to thermoelectric conversion substrate1via insulating film61. Specific examples of electronic component7are a large scale integration (LSI) circuit and a power semiconductor device (power device). Although not shown, when electronic component7is mounted to thermoelectric conversion substrate1via insulating film61, wirings, lands, through holes, and the like are formed on insulating film61, as needed.

It is preferable that thermally conductive layer62be provided on second surface22of insulating substrate2, and heat sink70be attached to thermally conductive layer62. A thermal interface material (TIM) such as grease is formed on thermally conductive layer62. Heat sink70is provided with, for example, creases to have a larger surface area. Specific examples of a material of heat sink70are aluminum and copper.

Connecting a DC power supply to second electrodes412and422and applying a voltage between the second electrodes412and422to make a current flow can transfer heat from one surface of insulating substrate2to the other surface due to the Peltier effect. Assume that first semiconductor311is a p-type semiconductor, and second semiconductor312is an n-type semiconductor. In this case, when a DC current flows from second semiconductor312to first semiconductor311, heat generated from electronic component7and transferred to insulating film61can be dissipated from the heat sink via thermally conductive layer62by forcibly transferring the heat from first surface21of insulating substrate2to second surface22.

In thermoelectric conversion module10shown inFIG. 6A, since first semiconductor311and second semiconductor312are respectively protected by first tubular member301and second tubular member302, damage to thermoelectric conversion unit3can be suppressed even upon loading on insulating substrate2. For example, a direction of loading on insulating substrate2is the thickness direction. However, the direction of loading is not limited to this.

As described above, heat transfers inside insulating substrate2, and insulating substrate2slightly thermally expands as the heat transfers. Even if the influence of this thermal expansion reaches first thermoelectric member31and second thermoelectric member32of thermoelectric conversion unit3, damage to thermoelectric conversion unit3can be suppressed because first semiconductor311and second semiconductor312are respectively protected by first tubular member301and second tubular member302. This configuration is especially effective when first tubular member301and second tubular member302each have a smaller thermal expansion coefficient than insulating substrate2.

[(First) Method for Producing Thermoelectric Conversion Substrate]

A method for producing thermoelectric conversion substrate1includes the following steps shown inFIGS. 8A to 8EandFIGS. 9A to 9C. This thermoelectric conversion substrate1is an example including one thermoelectric conversion unit3.FIGS. 10A to 10EandFIGS. 11A to 11Cshow an example including a plurality of thermoelectric conversion units3.FIGS. 10A to 10EandFIGS. 11A to 11Crespectively correspond toFIGS. 8A to 8EandFIGS. 9A to 9C, and hence the respective steps will be sequentially described mainly with reference toFIGS. 8A to 8EandFIGS. 9A to 9C.

In step A1, as shown inFIG. 8A, semi-cured core substrate8is prepared. A specific example of core substrate8is a prepreg. The prepreg is a semi-cured adhesive sheet obtained by impregnating a thermosetting resin composition in a reinforcing material. A specific example of the reinforcing material is glass cloth. A specific example of the thermosetting resin composition is a thermosetting resin composition impregnated with epoxy resin. A semi-cured state (stage B) means a state corresponding to an intermediate stage of a curing reaction between a varnished state (stage A) and a cured state (stage C). A thickness of core substrate8is greater than a length of each of first thermoelectric member31and second thermoelectric member32.

In step B1, as shown inFIG. 8B, a plurality of through holes80are formed in core substrate8. Through holes80can be formed by drilling. An inner diameter of through hole80is almost equal to an outer diameter of each of first thermoelectric member31and second thermoelectric member32. One thermoelectric conversion unit3has one first thermoelectric member31and one second thermoelectric member32. Accordingly, when thermoelectric conversion substrate1including one thermoelectric conversion unit3is produced, two through holes80are formed in core substrate8. When thermoelectric conversion substrate1including a plurality of thermoelectric conversion units3is produced, through holes80double in number than thermoelectric conversion units3are formed in core substrate8(seeFIG. 10B). Specific examples of an arrangement pattern of through holes80when viewed from the thickness direction are a lattice pattern (seeFIG. 12) and a staggered state. However, this is not limited. Pitch P (center-to-center distance) of two adjacent through holes80is between 0.5 mm and 2.1 mm (inclusive).

In step C1, first of all, first thermoelectric member31and second thermoelectric member32are prepared.

A method for producing first thermoelectric member31and second thermoelectric member32will be described below. First, as shown inFIG. 13, material3011(solid powder) for first semiconductor311is placed in container300. Container300may be vacuum or filled with a gas unreactive to material3011. First tubular member301is inserted into insertion opening310provided in container300. Material3011is sucked by first tubular member301while being heated at a temperature lower than a melting point. Material3011is then solid-phase sintered in first tubular member301to form first semiconductor311. Thereafter, as shown inFIG. 14, first thermoelectric member31shown inFIG. 2Ais obtained by slicing first tubular member301filled with first semiconductor311into discrete rings with cutter320. As described above, first thermoelectric member31is produced by filling first tubular member301with first semiconductor311. Subsequently, distal end portions341and351are preferably formed by respectively providing a Ti layer, an Ni layer, and a joining layer on both ends of first thermoelectric member31. The Ti layer can be formed by a sputtering method. The Ni layer and the joining layer can be formed by an electroless plating method. Second thermoelectric member32can be produced by using material3012of second semiconductor312and second tubular member302in the same manner as first thermoelectric member31. Second semiconductor312has carriers different from carriers of first semiconductor311. In this manner, second thermoelectric member32is produced by filling second tubular member302with second semiconductor312. First thermoelectric member31and second thermoelectric member32may be prepared in a step before step C1.

Functions of first thermoelectric member31and second thermoelectric member32can be directly inspected. In order to suppress variations in inspection, barrier films are preferably formed on both ends of first thermoelectric member31and second thermoelectric member32, respectively. Performing function inspection can sort first thermoelectric members31and second thermoelectric members32into non-defective products and defective products. Only first thermoelectric member31and second thermoelectric member32determined as non-defective products are selected and used for production of thermoelectric conversion substrate1. Since first thermoelectric member31and second thermoelectric member32can be used after inspection of each function, quality stability of thermoelectric conversion substrate1can be improved. This can reduce the possibility that a malfunction is found after production of thermoelectric conversion substrate1.

In step C1, as shown inFIG. 8C, at least one first thermoelectric member31and at least one second thermoelectric member32are inserted into the plurality of through holes80of core substrate8. This temporarily fix first thermoelectric member31and second thermoelectric member32and can improve positional accuracy. First thermoelectric member31and second thermoelectric member32each are located in the middle of through hole80in the depth direction. Since a thickness of core substrate8is greater than a length of each of first thermoelectric member31and second thermoelectric member32, recesses81are formed in both sides of each of first thermoelectric member31and second thermoelectric member32when first thermoelectric member31and second thermoelectric member32each are located in the middle of through hole80. When the arrangement pattern of through holes80when viewed from the thickness direction is a lattice pattern like that shown inFIG. 12, first thermoelectric members31and second thermoelectric members32are preferably alternately inserted in through holes80.

In step D1, as shown inFIG. 8C, metal foils9are stacked on both surfaces of core substrate8and then hot-pressed core substrate8with metal foils9to form insulating substrate2like that shown inFIG. 8D. Metal foils9are stacked on core substrate8so as to cover all through holes80. A specific example of metal foil9is a copper foil. Semi-cured core substrate8is hot-pressed to be cured to form insulating substrate2. At the time of hot pressing, a resin forming core substrate8partially flows into recesses81to fill recesses81, thereby forming flat first surface21and second surface22of insulating substrate2. Conditions for hot pressing are not specifically limited.

In step E1, as shown inFIG. 8E, a portion of metal foils9at a position corresponding to each of locations of first thermoelectric member31and second thermoelectric member32is removed. That is, the portion of metal foils9to be removed is a portion at which first thermoelectric member31or second thermoelectric member32exists immediately below when metal foils9are viewed from the thickness direction. From this, recess portion901having first surface21as a bottom surface and recess portion902having second surface22as a bottom surface are formed. Each of removal areas of metal foils9is preferably smaller than an area of a corresponding one of distal end faces321and331of first thermoelectric member31and distal end faces322and332of second thermoelectric member32. That is, an area of recess portion901of first surface21is preferably smaller than an area of each of distal end faces321and322of first thermoelectric member31and second thermoelectric member32. And an area of recess portion902of second surface22is preferably smaller than an area of each of distal end faces331and332of first thermoelectric member31and second thermoelectric member32. Metal foil9can be removed by, for example, etching.

In step F1, as shown inFIG. 9A, portions of insulating substrate2at which metal foil9has been removed are removed to expose distal end faces321and331of first thermoelectric member31and distal end faces322and332of second thermoelectric member32. Removing the above portions of insulating substrate2can form first opening portion201and second opening portion202in first surface21of insulating substrate2and third opening portion211and fourth opening portion212in second surface22of insulating substrate2. Insulating substrate2can be removed by, for example, irradiation with a CO2laser (carbon dioxide laser).

In step G1, as shown inFIG. 9B, plating is provided, ranging from distal end faces321and331of first thermoelectric member31and distal end faces322and332of second thermoelectric member32to metal foils9. In this case, first opening portion201, second opening portion202, third opening portion211, and fourth opening portion212may be filled with plating to form filled vias.

In step H1, as shown inFIG. 9C, metal foil9on first surface21of insulating substrate2is partially removed to form first electrode41that electrically connects first thermoelectric member31to second thermoelectric member32. In this case, metal foil9on second surface22of insulating substrate2may be partially removed to form second electrodes412and422for power supply connection. In this manner, thermoelectric conversion substrate1shown inFIG. 1Acan be produced.

The method for producing thermoelectric conversion substrate1including a plurality of thermoelectric conversion units3further includes following steps.

In step I1 as shown inFIG. 11C, metal foil9on second surface22of insulating substrate2is partially removed to form second electrode42. Second electrode42electrically connects first thermoelectric member31to second thermoelectric member32, which differ from first thermoelectric member31and second thermoelectric member32which are electrically connected to each other by first electrode41. That is, second electrode42electrically connects first semiconductor311of first thermoelectric member31of one thermoelectric conversion unit3(thermoelectric conversion unit3on the right side inFIG. 11C) to second semiconductor312of second thermoelectric member32of another thermoelectric conversion unit3(thermoelectric conversion unit3on the left side inFIG. 11C). In this manner, thermoelectric conversion substrate1shown inFIG. 1Bcan be produced.

[(Second) Method for Producing Thermoelectric Conversion Substrate]

A method for producing thermoelectric conversion substrate1includes following steps shown inFIGS. 15A to 15EandFIGS. 16A to 16C. Thermoelectric conversion substrate1is an example including one thermoelectric conversion unit3.FIGS. 17A to 17EandFIG. 18A to 18Cshow an example including a plurality of thermoelectric conversion units3.FIGS. 17A to 17EandFIGS. 18A to 18Crespectively correspond toFIGS. 15A to 15EandFIGS. 16A to 16C, and hence the respective steps will be sequentially described mainly with reference toFIGS. 15A to 15EandFIGS. 16A to 16C.

In step A1-2, as shown inFIG. 15A, cured core insulating layer50is prepared. A specific example of core insulating layer50is a cured prepreg. A thickness of core insulating layer50is almost equal to a length of each of first thermoelectric member31and second thermoelectric member32.

In step B1-2, as shown inFIG. 15B, a plurality of through holes80are formed in core insulating layer50. Details of this step are almost the same as details of step B1.

In step C1-2, as in step C1, first of all, first thermoelectric member31and second thermoelectric member32are prepared.

Functions of first thermoelectric member31and second thermoelectric member32can be directly inspected. In order to suppress variations in inspection, barrier films are preferably formed on both ends of first thermoelectric member31and second thermoelectric member32, respectively. Performing function inspection can sort first thermoelectric members31and second thermoelectric members32into non-defective products and defective products. Only first thermoelectric member31and second thermoelectric member32determined as non-defective products are selected and used for production of thermoelectric conversion substrate1. Since first thermoelectric member31and second thermoelectric member32can be used after inspection of each function, quality stability of thermoelectric conversion substrate1can be improved. This can reduce the possibility that a malfunction is found after production of thermoelectric conversion substrate1.

In step C1-2, as shown inFIG. 15C, at least one first thermoelectric member31and at least one second thermoelectric member32are inserted into the plurality of through holes80of core insulating layer50. Since a thickness of core insulating layer50is almost equal to a length of each of first thermoelectric member31and second thermoelectric member32, a surface of core insulating layer50is almost flush with distal end faces321and331of first thermoelectric member31and distal end faces322and332of second thermoelectric member32. When the arrangement pattern of through holes80when viewed from the thickness direction is a lattice pattern like that shown inFIG. 12, first thermoelectric members31and second thermoelectric members32are preferably alternately inserted in through holes80.

In step D1-2, as shown inFIG. 15C, metal foil9is stacked on one surface of core insulating layer50via semi-cured first insulating layer51, and metal foil9is stacked on the other surface of core insulating layer50via semi-cured second insulating layer52. And then core insulating layer50, semi-cured first insulating layer51, semi-cured second insulating layer52, and metal foils9are hot-pressed to form insulating substrate2like that shown inFIG. 15D. A specific example of each of semi-cured first insulating layer51and semi-cured second insulating layer52is a prepreg. Insulating substrate2includes multilayer structure53constituted by core insulating layer50, cured first insulating layer51, and cured second insulating layer52. As has been described already, a thermal conductivity of each of first insulating layer51and second insulating layer52may be set to be higher than a thermal conductivity of core insulating layer50. Metal foils9are stacked on core insulating layer50so as to cover all through holes80. A specific example of metal foil9is a copper foil. Conditions for hot pressing are not specifically limited.

In step E1-2, as shown inFIG. 15E, portions of metal foils9at a position corresponding to each of locations of first thermoelectric member31and second thermoelectric member32are removed. Details of this step are almost the same as details of step E1.

In step F1-2, as shown inFIG. 16A, portions of insulating substrate2at which metal foil9has been removed are removed to expose distal end faces321and331of first thermoelectric member31and distal end faces322and332of second thermoelectric member32. Details of this step are almost the same as details of step F1.

In step G1-2, as shown inFIG. 16B, plating is provided, ranging from distal end faces321and331of first thermoelectric member31and distal end faces322and332of second thermoelectric member32to metal foils9. Details of this step are almost the same as details of step G1.

In step H1-2, as shown inFIG. 16C, metal foil9on first surface21of insulating substrate2is partially removed to form first electrode41that electrically connects first thermoelectric member31to second thermoelectric member32. Details of this step are almost the same as details of step H1.

The method for producing thermoelectric conversion substrate1including a plurality of thermoelectric conversion units3further includes following steps.

In step I1-2, as shown inFIG. 18C, metal foil9on second surface22of insulating substrate2is partially removed to form second electrode42. Second electrode42electrically connects first thermoelectric member31to second thermoelectric member32, which differ from first thermoelectric member31and second thermoelectric member32which are electrically connected to each other by first electrode41. Details of this step are almost the same as details of step I1.

[(Third) Method for Producing Thermoelectric Conversion Substrate]

FIGS. 19A to 19EandFIGS. 20A to 20Cshow an example of the method for producing thermoelectric conversion substrate1incorporating wiring layers43shown inFIG. 4A. The step shown inFIG. 15Ais the same as the steps shown inFIGS. 15A to 15EandFIGS. 16A to 16Cexcept that cured core insulating layer50having surfaces provided with wiring layers43is used in place of cured core insulating layer50.

FIGS. 21A to 21EandFIGS. 22A to 22Cshow an example of the method for producing thermoelectric conversion substrate1incorporating wiring layers43shown inFIG. 4B. The step shown inFIG. 17Ais the same as the steps shown inFIGS. 17A to 17EandFIGS. 18A to 18Cexcept that cured core insulating layer50having surfaces provided with wiring layers43is used in place of cured core insulating layer50. Cured core insulating layer50having surfaces provided with wiring layers43can be obtained by, for example, patterning a multilayer metal-clad plate using a subtractive method or patterning an unclad plate using an additive method.

In the above production method as well, a thermal conductivity of each of first insulating layer51and second insulating layer52may be set to be higher than a thermal conductivity of core insulating layer50.

[(Fourth) Method For Producing Thermoelectric Conversion Substrate]

The method for producing thermoelectric conversion substrate1includes following steps shown inFIGS. 23A to 23EandFIGS. 24A to 24C. This thermoelectric conversion substrate1is an example including one thermoelectric conversion unit3.FIGS. 25A to 25EandFIGS. 26A to 26Cshow an example including a plurality of thermoelectric conversion units3.FIGS. 25A to 25EandFIGS. 26A to 26Crespectively correspond toFIGS. 23A to 23EandFIGS. 24A to 24C, and hence the respective steps will be sequentially described mainly with reference toFIGS. 23A to 23EandFIGS. 24A to 24C.

In step A2, as shown inFIG. 23A, first metal foil91is prepared. A specific example of first metal foil91is a copper foil.

In step B2, first of all, as in step C1, first thermoelectric member31and second thermoelectric member32are prepared.

Functions of first thermoelectric member31and second thermoelectric member32can be directly inspected. In order to suppress variations in inspection, barrier films are preferably formed on both ends of first thermoelectric member31and second thermoelectric member32, respectively. Performing function inspection can sort first thermoelectric members31and second thermoelectric members32into non-defective products and defective products. Only first thermoelectric member31and second thermoelectric member32determined as non-defective products are selected and used for production of thermoelectric conversion substrate1. Since first thermoelectric member31and second thermoelectric member32can be used after inspection of each function, quality stability of thermoelectric conversion substrate1can be improved. This can reduce the possibility that a malfunction is found after production of thermoelectric conversion substrate1.

In step B2, as shown inFIG. 23B, at least one first thermoelectric member31and at least one second thermoelectric member32are soldered to first metal foil91. Distal end face331of first thermoelectric member31and distal end face332of second thermoelectric member32are brought into contact with and soldered to one surface of first metal foil91.

In step C2, semi-cured core substrate8is prepared. A specific example of semi-cured core substrate8is a prepreg. Core substrate8has opening portion800. When core substrate8is viewed from the thickness direction, opening portion800is formed to have a size large enough to accommodate all first thermoelectric members31and second thermoelectric members32. A thickness of core substrate8is preferably greater than a length of each of first thermoelectric member31and second thermoelectric member32.

In step C2, as shown inFIG. 23C, core substrate8is stacked on first metal foil91so as to accommodate first thermoelectric member31and second thermoelectric member32in opening portion800. If the thickness of core substrate8is greater than the length of each of first thermoelectric member31and second thermoelectric member32, the surface of core substrate8is located at a position higher than distal end face321of first thermoelectric member31and distal end face322of second thermoelectric member32.

In step D2, as shown inFIG. 23D, second metal foil92is stacked on core substrate8and then hot-pressed so as to close opening portion800, thereby forming insulating substrate2from cured product of core substrate8. A specific example of second metal foil92is a copper foil. At the time of hot pressing, a resin forming core substrate8partially flows into opening portion800to fill opening portion800, thereby forming flat first surface21and second surface22of insulating substrate2. Conditions for hot pressing are not specifically limited.

In step E2, as shown inFIG. 23E, portions of second metal foil92at a position corresponding to each of locations of first thermoelectric member31and second thermoelectric member32are removed. That is, the portion of second metal foil92to be removed is a portion at which first thermoelectric member31or second thermoelectric member32exists immediately below when second metal foil92is viewed from the thickness direction. From this, recess portion901having first surface21as a bottom surface is formed. Each of removal areas of second metal foil92is preferably smaller than an area of a corresponding one of distal end faces321and322of first thermoelectric member31and second thermoelectric member32. That is, an area of recess portion901of first surface21is preferably smaller than an area of each of distal end faces321and322of first thermoelectric member31and second thermoelectric member32. Second metal foil92can be removed by, for example, etching.

In step F2, as shown inFIG. 24A, portions of insulating substrate2at which second metal foil92has been removed are removed to expose distal end face321of first thermoelectric member31and distal end face322of second thermoelectric member32. Removing the above portions of insulating substrate2can form first opening portion201and second opening portion202in first surface21of insulating substrate2. Insulating substrate2can be removed by, for example, irradiation with a CO2laser (carbon dioxide laser).

In step G2, as shown inFIG. 24B, plating is provided, ranging from distal end face321of first thermoelectric member31and distal end face322of second thermoelectric member32to second metal foil92. In this case, first opening portion201and second opening portion202may be filled with plating to form filled vias.

In step H2, as shown inFIG. 24C, second metal foil92on first surface21of insulating substrate2is partially removed to form first electrode41that electrically connects first thermoelectric member31to second thermoelectric member32. In this case, first metal foil91on second surface22of insulating substrate2may be partially removed to form second electrodes412and422for power supply connection. In this manner, thermoelectric conversion substrate1shown inFIG. 5Acan be produced.

The method for producing thermoelectric conversion substrate1including a plurality of thermoelectric conversion units3further includes following steps.

In step I2, as shown inFIG. 26C, first metal foil91on second surface22of insulating substrate2is partially removed to form second electrode42that electrically connects first thermoelectric member31to second thermoelectric member32, which differ from first thermoelectric member31and second thermoelectric member32which are electrically connected by first electrode41. That is, second electrode42electrically connects first semiconductor311of first thermoelectric member31of one thermoelectric conversion unit3(thermoelectric conversion unit3on the right side inFIG. 26C) to second semiconductor312of second thermoelectric member32of another thermoelectric conversion unit3(thermoelectric conversion unit3on the left side inFIG. 26C). In this manner, thermoelectric conversion substrate1shown inFIG. 5Bcan be produced.

[(Fifth) Method for Producing Thermoelectric Conversion Substrate]

A method for producing thermoelectric conversion substrate1includes following steps shown inFIGS. 27A to 27EandFIGS. 28A to 28C. Thermoelectric conversion substrate1is an example including one thermoelectric conversion unit3.FIGS. 29A to 29EandFIG. 30A to 30Cshow an example including a plurality of thermoelectric conversion units3.FIGS. 29A to 29EandFIGS. 30A to 30Crespectively correspond toFIGS. 27A to 27EandFIGS. 28A to 28C, and hence the respective steps will be sequentially described mainly with reference toFIGS. 27A to 27EandFIGS. 28A to 28C.

In step A2-2, as shown inFIG. 27A, first metal foil91is prepared. A specific example of first metal foil91is a copper foil.

In step B2-2, first of all, as in step C1, first thermoelectric member31and second thermoelectric member32are prepared.

Functions of first thermoelectric member31and second thermoelectric member32can be directly inspected. In order to suppress variations in inspection, barrier films are preferably formed on both ends of first thermoelectric member31and second thermoelectric member32, respectively. Performing function inspection can sort first thermoelectric members31and second thermoelectric members32into non-defective products and defective products. Only first thermoelectric member31and second thermoelectric member32determined as non-defective products are selected and used for production of thermoelectric conversion substrate1. Since first thermoelectric member31and second thermoelectric member32can be used after inspection of each function, quality stability of thermoelectric conversion substrate1can be improved. This can reduce the possibility that a malfunction is found after production of thermoelectric conversion substrate1.

In step B2-2, as shown inFIG. 27B, at least one first thermoelectric member31and at least one second thermoelectric member32are soldered to first metal foil91. Distal end face331of first thermoelectric member31and distal end face332of second thermoelectric member32are brought into contact with and soldered to one surface of first metal foil91.

In step C2-2, cured core insulating layer50is prepared. A specific example of core insulating layer50is a cured prepreg. Core insulating layer50has opening portion800. When core insulating layer50is viewed from the thickness direction, opening portion800is formed to have a size large enough to accommodate all first thermoelectric members31and second thermoelectric members32.

In step C2-2, as shown inFIG. 27C, core insulating layer50is stacked on first metal foil91so as to accommodate first thermoelectric member31and second thermoelectric member32in opening portion800.

In step D2-2, as shown inFIG. 27C, second metal foil92is stacked on core insulating layer50via semi-cured first insulating layer51and then hot-pressed so as to close opening portion800, thereby forming insulating substrate2like that shown inFIG. 27D. A specific example of semi-cured first insulating layer51is a prepreg. Insulating substrate2is formed from multilayer structure53constituted by core insulating layer50and cured first insulating layer51. At the time of hot pressing, a resin forming first insulating layer51partially flows into opening portion800to fill opening portion800, thereby forming flat first surface21and second surface22of insulating substrate2. Conditions for hot pressing are not specifically limited.

In step E2-2, as shown inFIG. 27E, portions of second metal foil92at a position corresponding to each of locations of first thermoelectric member31and second thermoelectric member32are removed. Details of this step are almost the same as details of step E2.

In step F2-2, as shown inFIG. 28A, portions of insulating substrate2at which second metal foil92has been removed are removed to expose distal end face321of first thermoelectric member31and distal end face322of second thermoelectric member32. Details of this step are almost the same as details of step F2.

In step G2-2, as shown inFIG. 28B, plating is provided, ranging from distal end face321of first thermoelectric member31and distal end face322of second thermoelectric member32to second metal foil92. Details of this step are almost the same as details of step G1.

In step H2-2, as shown inFIG. 28C, second metal foil92on first surface21of insulating substrate2is partially removed to form first electrode41that electrically connects first thermoelectric member31to second thermoelectric member32. Details of this step are almost the same as details of step H1.

The method for producing thermoelectric conversion substrate1including a plurality of thermoelectric conversion units3further includes following steps.

In step I2-2, as shown inFIG. 30C, first metal foil91on second surface22of insulating substrate2is partially removed to form second electrode42that electrically connects first thermoelectric member31to second thermoelectric member32, which differ from first thermoelectric member31and second thermoelectric member32which are electrically connected by first electrode41. Details of this step are almost the same as details of step I2.

[(Sixth) Method For Producing Thermoelectric Conversion Substrate]

The method for producing thermoelectric conversion substrate1includes following steps shown inFIGS. 31A to 31EandFIGS. 32A to 32C. The respective steps will be sequentially described below.

In step A3, as shown inFIG. 31A, base substrate242including at least one second electrode42is prepared. Base substrate242is a cured substrate. Second electrodes412and422for power supply connection are preferably provided on the same surface on which second electrode42of base substrate242is provided. Base substrate242can be obtained by, for example, patterning a multilayer metal-clad plate using a subtractive method or patterning an unclad plate using an additive method.

In step B3, first of all, as in step C1, first thermoelectric member31and second thermoelectric member32are prepared.

Functions of first thermoelectric member31and second thermoelectric member32can be directly inspected. In order to suppress variations in inspection, barrier films are preferably formed on both ends of first thermoelectric member31and second thermoelectric member32, respectively. Performing function inspection can sort first thermoelectric members31and second thermoelectric members32into non-defective products and defective products. Only first thermoelectric member31and second thermoelectric member32determined as non-defective products are selected and used for production of thermoelectric conversion substrate1. Since first thermoelectric member31and second thermoelectric member32can be used after inspection of each function, quality stability of thermoelectric conversion substrate1can be improved. This can reduce the possibility that a malfunction is found after production of thermoelectric conversion substrate1.

In step B3, as shown inFIG. 31B, one first thermoelectric member31and one second thermoelectric member32are soldered to second electrode42. When second electrodes412and422are provided on base substrate242, first thermoelectric member31is soldered to second electrode412, and second thermoelectric member32is soldered to second electrode422.

In step C3, as shown inFIG. 31C, semi-secured core substrate8having opening portion800is prepared, and core substrate8is stacked on base substrate242so as to accommodate first thermoelectric member31and second thermoelectric member32in opening portion800. Details of this step are almost the same as details of step C2.

In step D3, as shown inFIG. 31D, metal foil9is stacked on core substrate8and then hot-pressed so as to close opening portion800, thereby forming insulating substrate2from cured product of core substrate8. At the time of hot pressing, a resin forming core substrate8partially flows into opening portion800so as to fill opening portion800, thereby forming flat first surface21of insulating substrate2. Second surface22is formed on the interface between insulating substrate2and base substrate242. Conditions for hot pressing are not specifically limited.

In step E3, as shown inFIG. 31E, portions of metal foil9at a position corresponding to each of locations of first thermoelectric member31and second thermoelectric member32are removed. Details of this step are almost the same as details of step E2.

In step F3, as shown inFIG. 32A, portions of insulating substrate2at which metal foil9has been removed are removed to expose distal end face321of first thermoelectric member31and distal end face322of second thermoelectric member32. Details of this step are almost the same as details of step F2.

In step G3, as shown inFIG. 32B, plating is provided, ranging from distal end face321of first thermoelectric member31and distal end face322of second thermoelectric member32to metal foil9. In this case, first opening portion201and second opening portion202may be filled with plating to form filled vias.

In step H3, as shown inFIG. 32C, metal foil9on first surface21of insulating substrate2is partially removed to form first electrode41that electrically connects first thermoelectric member31to second thermoelectric member32.

[(Seventh) Method for Producing Thermoelectric Conversion Substrate]

A method for producing thermoelectric conversion substrate1includes following steps shown inFIGS. 33A to 33EandFIGS. 34A to 34C. Thermoelectric conversion substrate1is an example including one thermoelectric conversion unit3.FIGS. 35A to 35EandFIG. 36A to 36Cshow an example including a plurality of thermoelectric conversion units3.FIGS. 35A to 35EandFIGS. 36A to 36Crespectively correspond toFIGS. 33A to 33EandFIGS. 34A to 34C, and hence the respective steps will be sequentially described mainly with reference toFIGS. 33A to 33EandFIGS. 34A to 34C.

In step A4, as shown inFIG. 33A, first metal foil91is prepared. A specific example of first metal foil91is a copper foil.

In step B4, as in step C1, first thermoelectric member31and second thermoelectric member32are prepared.

Functions of first thermoelectric member31and second thermoelectric member32can be directly inspected. In order to suppress variations in inspection, barrier films are preferably formed on both ends of first thermoelectric member31and second thermoelectric member32, respectively. Performing function inspection can sort first thermoelectric members31and second thermoelectric members32into non-defective products and defective products. Only first thermoelectric member31and second thermoelectric member32determined as non-defective products are selected and used for production of thermoelectric conversion substrate1. Since first thermoelectric member31and second thermoelectric member32can be used after inspection of each function, quality stability of thermoelectric conversion substrate1can be improved. This can reduce the possibility that a malfunction is found after production of thermoelectric conversion substrate1.

In step B4, as shown inFIG. 33B, at least one first thermoelectric member31and at least one second thermoelectric member32are soldered to first metal foil91. Distal end face331of first thermoelectric member31and distal end face332of second thermoelectric member32are brought into contact with and soldered to one surface of first metal foil91.

In step C4, cured or semi-cured core substrate8is prepared. As described above, core substrate8may be cured or semi-cured. A specific example of cured core substrate8is a cured prepreg. A specific example of semi-cured core substrate8is a prepreg. Core substrate8has opening portion800. When core substrate8is viewed from the thickness direction, opening portion800is formed to have a size large enough to accommodate all first thermoelectric members31and second thermoelectric members32. A thickness of core substrate8is preferably greater than a length of each of first thermoelectric member31and second thermoelectric member32.

In step C4, as shown inFIG. 33C, core substrate8is stacked on first metal foil91so as to accommodate first thermoelectric member31and second thermoelectric member32in opening portion800. If the thickness of core substrate8is greater than the length of each of first thermoelectric member31and second thermoelectric member32, the surface of core substrate8is located at a position higher than distal end face321of first thermoelectric member31and distal end face322of second thermoelectric member32.

In this case, in place of core substrate8having opening portion800described above, although not shown, a mold having an opening portion having the same shape may be used.

In step D4, as shown inFIG. 33D, resin54is poured into opening portion800to fill opening portion800. Resin54is preferably a liquid thermosetting resin.

In step D4, as shown inFIG. 33D, second metal foil92is stacked on core substrate8and then hot-pressed so as to close opening portion800filled with resin54, thereby forming insulating substrate2from cured product of core substrate8and cured resin54. A specific example of second metal foil92is a copper foil. In the case of the above production method, as compared with a thermal conductivity of cured resin54, a thermal conductivity of surrounding core substrate8may be set to be high. Conditions for hot pressing are not specifically limited.

In this case, in step C4, when the above mold is used, resin54may be injected and filled in the opening portion of the mold by transfer molding and heated and cured. Subsequently, cured resin54may be removed from the mold. Subsequently, processing follows following steps.

In step E4, as shown inFIG. 33E, portions of second metal foil92at a position corresponding to each of locations of first thermoelectric member31and second thermoelectric member32are removed. Details of this step are almost the same as details of step E2.

In step F4, as shown inFIG. 34A, portions of insulating substrate2at which second metal foil92has been removed are removed to expose distal end face321of first thermoelectric member31and distal end face322of second thermoelectric member32. Details of this step are almost the same as details of step F2.

In step G4, as shown inFIG. 34B, plating is provided, ranging from distal end face321of first thermoelectric member31and distal end face322of second thermoelectric member32to second metal foil92. Details of this step are almost the same as details of step G2.

In step H4, as shown inFIG. 34C, second metal foil92on first surface21of insulating substrate2is partially removed to form first electrode41that electrically connects first thermoelectric member31to second thermoelectric member32. In this case, first metal foil91on second surface22of insulating substrate2may be partially removed to form second electrodes412and422for power supply connection. Details of this step are almost the same as details of step H2.

Electronic components including the thermoelectric conversion module and the thermoelectric conversion substrate according to the present disclosure can be installed, for example, on partition walls that partition the insides and outsides of houses or electronic devices and widely used for various purposes, e.g., cooling and heating inside temperatures and generating power using temperature differences between the insides and the ousides.