JP4690700B2 - Thermoelectric conversion device and method of manufacturing thermoelectric conversion device - Google Patents

Description

  The present invention relates to a thermoelectric conversion device capable of converting heat into electricity or capable of converting electricity into heat, and a method of manufacturing the thermoelectric conversion device.

  Thermoelectric conversion devices are devices that use thermoelectric effects such as the Thomson effect, Peltier effect, Seebeck effect, and have already been mass-produced as temperature adjustment units that convert electricity into heat. Research and development is also underway as a power generation unit that converts heat into electricity. A thermoelectric conversion device as a power generation unit is arranged in a state where a plurality of thermoelectric elements are sandwiched between two insulating substrates having electrodes so that they are electrically in series and thermally in parallel.

  In order to bring the power generation efficiency of the thermoelectric conversion device close to the power generation efficiency of the thermoelectric element itself, it is necessary to smoothly supply heat to one end of the thermoelectric element and release heat from the other end of the thermoelectric element. For this reason, a ceramic substrate excellent in heat conduction is used for each insulating substrate. Furthermore, the electrode disposed at the end of the thermoelectric element is made of a material having a low electrical resistance. Each electrode and the thermoelectric conversion element are joined with solder.

  In order to make it possible to use exhaust heat power generation in a wide field, it is conceivable to design a high usable temperature of the thermoelectric conversion device. However, in order to increase the usable temperature, it is necessary to prevent the thermoelectric element from being oxidized. For example, it is necessary to take measures such as making the use environment a non-oxidizing atmosphere or making the thermoelectric conversion device an airtight sealed structure.

  Therefore, conventionally, a lid portion is provided outside one substrate, and one end portion of the frame portion is joined to this lid portion, and the other end portion of the frame portion is placed on the surface on which the electrode of the other substrate is provided. An airtight sealing structure has been realized by joining and airtight inside.

  However, conventionally, since the end portion of the frame portion is bonded to the surface of the substrate on which the electrode is provided, a thermoelectric element cannot be disposed at this bonded portion. Further, if the bonding strength between the frame portion and the substrate is increased to improve the airtightness inside the apparatus, it is necessary to widen the bonding portion, and the installation density of the thermoelectric elements is lowered.

  The present invention has been made in view of the above, and an object of the present invention is to improve the bonding strength between the frame and the substrate and the air tightness inside the apparatus without causing a decrease in the installation density of the thermoelectric elements. There is.

The thermoelectric conversion device according to the first aspect of the present invention includes a first substrate and a second substrate each having a plurality of electrodes on the surface, one end serving as an electrode of the first substrate, and the other end serving as an electrode of the second substrate. A plurality of thermoelectric elements disposed between the first substrate and the second substrate so as to correspond to each other, a lid portion disposed on the side of the second substrate not provided with the electrode, and a lid portion as pressed against the first substrate, it is bonded to the surface towards the one end portion is not provided with the first substrate electrode having a frame portion joined to the lid and another end portion, the first substrate electrode The first metal foil is disposed on the surface where the first metal foil is not provided, and one end portion of the frame portion is joined to the first substrate via the second metal foil, and one end portion of the frame portion And the thickness of the second metal foil is made thinner than the thickness of the first metal foil .

In the present invention, the installation density of the thermoelectric elements joined to the electrodes of the first substrate is improved by joining one end of the frame portion to the surface on which the electrodes of the first substrate are not provided. . In addition, the bonding area between the end portion of the frame portion and the first substrate can be increased, and the bonding strength of the bonding portion and the airtightness inside the apparatus are improved.
In the present invention, the thickness of the one end portion of the frame portion and the second metal foil is made thinner than the thickness of the first metal foil, so that the frame portion is outside the contact with the first metal foil. The one end portion of the frame is not contacted to prevent an increase in the amount of heat flowing in the frame portion.

In the thermoelectric conversion device, the lid portion is provided with a bent portion that is bent in the pressing direction inside a joint portion with the frame portion .

In the present invention, since the lid portion is provided with a bent portion that bends in the pressing direction inside the joint portion with the frame portion, the lid portion is welded to the frame portion while pressing the lid portion against the second substrate. Assembling is facilitated.

The manufacturing method of the thermoelectric conversion device according to the second aspect of the present invention includes a step of arranging solder for joining a plurality of thermoelectric elements on the plurality of electrodes on the first substrate, and a method corresponding to the plurality of electrodes. Soldering one end portion of the thermoelectric element, joining the one end portion of the frame portion to the surface of the first substrate on which the electrode is not provided, and a plurality of electrodes on the second substrate comprising a plurality of thermoelectric elements. A step of disposing the second substrate so as to correspond to each of the other end portions of the element; a lid portion being disposed outside the second substrate; and the other end portion of the frame portion so as to press the second substrate against the first substrate ; And a step of joining the lid portion.

  In the present invention, after soldering one end portion of the corresponding thermoelectric element on the plurality of electrodes, the one end portion of the frame portion is joined to the surface of the first substrate where the electrode is not provided. The frame portion is not disturbed during soldering, and solder printing can be applied when soldering the thermoelectric element.

  ADVANTAGE OF THE INVENTION According to this invention, the joining strength of a frame part and a board | substrate and the airtightness inside an apparatus can be improved, without causing the fall of the installation density of the thermoelectric element in a thermoelectric conversion apparatus.

  Hereinafter, a thermoelectric conversion device according to an embodiment will be described with reference to the drawings.

  FIG. 1 is a cross-sectional view illustrating a schematic configuration of the thermoelectric conversion device 1, and FIG. 2 is a perspective cross-sectional view of the thermoelectric conversion device 1 as viewed from below. FIG. 1 shows a schematic configuration of the AA portion of FIG.

  The thermoelectric conversion device 1 includes a first substrate 9 having a plurality of electrodes 8 on the surface, a second substrate 15 having a plurality of electrodes 14 on the surface, and a plurality of p-types disposed between these substrates. It has a thermoelectric element 5 and a plurality of n-type thermoelectric elements 6. Each thermoelectric element 5, 6 is arranged so that one end thereof corresponds to the electrode 8 of the first substrate 9 and the other end thereof corresponds to the electrode 14 of the second substrate 15. Then, the lid portion 2 is disposed on the surface of the second substrate 15 where the electrode 14 is not provided, and one end of the frame portion 4 is applied so that pressure is applied between the lid portion 2 and the first substrate 9. The part is joined to the surface of the first substrate 9 where the electrode 8 is not provided, and the other end of the frame part 4 is joined to the lid part 2. The electrodes 8 and 14 are arranged so that all the thermoelectric elements 5 and 6 are electrically connected in series. Moreover, each thermoelectric element 5 and 6 is thermally arranged in parallel. For convenience of explanation, FIG. 1 shows a state in which the number of thermoelectric elements 5 and 6 is reduced, and FIG. 2 omits the lid, the second substrate 15, the electrode 14 and the like.

  In the present embodiment, one end portion of the frame portion 4 is bonded to the surface of the first substrate 9 where the electrode 8 is not provided, that is, the other main surface different from the main surface to which the thermoelectric element is bonded. By arranging to join in the joining region provided on the surface, the installation density of the thermoelectric elements 5 and 6 joined to the electrodes 8 of the first substrate 9 is improved. Further, if the surface of the first substrate 9 where the electrode 8 is not provided, the bonding area between the one end portion of the frame portion 4 and the first substrate 9 can be increased, so that the bonding strength and A sufficient bonding area can be ensured to improve the airtightness inside the apparatus.

  By improving the installation density of the thermoelectric elements 5 and 6, the power generation performance per unit area of the thermoelectric conversion device 1 is improved. That is, compared with the conventional apparatus, if the installation area is the same, the power generation output can be increased, and if the power generation output is the same, the size can be further reduced.

  The lid 2 and the first substrate 9 are members that come into thermal contact with the outside, respectively, and enable heat to be transferred to the outside. For example, when the lid 2 shown in FIG. 1 is the heat absorption side and the first substrate 9 is the heat dissipation side, the heat supplied from the outside is given to the thermoelectric elements 5 and 6 through the lid 2. Heat is converted into electricity by each thermoelectric element 5, 6, and the heat passes through the metal foil 10 (first metal foil) disposed on the surface (back surface) of the first substrate 9 where the electrode 8 is not provided. The metal foil 10 flows out to an external member (not shown) that comes into contact.

  The most advanced thermoelectric element electrically connected in series is the metal foil 18 disposed on the back surface of the first substrate 9 through a through hole (not shown) provided in the first substrate 9. And the one at the final end is connected to a metal foil 19 (not shown) disposed on the back surface of the first substrate 9 through a through hole (not shown) provided in the first substrate 9. The electricity generated by the thermoelectric elements 5 and 6 is taken out through the metal foils 18 and 19.

  FIG. 3 is an enlarged view of the lower right portion of the thermoelectric conversion device 1 shown in FIG. As shown in the figure, one end portion of the frame portion 4 is joined to a surface (back surface) of the first substrate 9 on which the electrode 8 is not provided via a metal foil 11 (second metal foil). The metal foil 11 is brazed to the first substrate 9 with a brazing material 20. And the one end part of the frame part 4 is welded with respect to this metal foil 11 with the laser irradiated from the arrow direction of the figure. By joining one end of the frame part 4 to the back surface of the first substrate 9 in this way, the joining area of the metal foil 11 to the first substrate 9 can be increased, and the joining strength by brazing can be increased. it can.

  In addition, in FIG. 3, although the width | variety of the folding | turning part in the front-end | tip of the frame part 4 was shown by the length substantially the same as the width | variety of the metal foil 11, it is not restricted to this. For example, as shown in the enlarged view of FIG. 4, it is desirable that the width of the folded portion of the frame portion 4 is ½ of the width of the metal foil 11. The width of the folded portion of the frame portion 4 is preferably determined in consideration of the difficulty of peeling when the frame portion 4 and the metal foil 11 are welded by laser welding.

  By the way, in order to increase the power generation efficiency of the thermoelectric conversion device 1, it is necessary to increase the amount of heat given from the lid 2 to each thermoelectric element 5, 6 and to suppress the amount of heat flowing out from the lid 2 to the frame 4.

  Therefore, in the present embodiment, the total thickness of the one end portion of the frame portion 4 and the metal foil 11 is set to be thinner than the thickness of the metal foil 10. Thereby, since the frame part 4 which directly connects the lid part 2 and the first substrate 9 does not contact the outside like the metal foil 10, it is possible to suppress an increase in the amount of heat flowing in the frame part. . In order to reduce the amount of heat flowing from the lid 2 to the frame 4, it is effective to increase the thermal resistance by shortening the thickness and width of the entire frame.

  In the thermoelectric conversion device 1, the operating temperature on the high temperature side is set to 600 ° C., for example. In order to withstand this temperature, p-type and n-type thermoelectric elements having a skutterudite structure are used for the thermoelectric elements 5 and 6, and the thermoelectric elements 5 and 6 are oxidized in an air atmosphere at 600 ° C. In order to prevent this, the apparatus has an airtight sealing structure with the lid portion 2, the frame portion 4, and the first substrate 9.

  The lid 2 and the frame 4 are preferably made of the same metal in order to facilitate and ensure the joining of both. Here, Kovar is used as an example. Moreover, as metal foil 10,11,18, the thing made from copper is used, for example.

  Next, the thermoelectric conversion device 1 will be described in more detail with reference to FIG. One end of each thermoelectric element 5, 6 is joined to the corresponding electrode 8 on the first substrate 9 by solder 7. On the other hand, a conductive member capable of absorbing the expansion and contraction of the thermoelectric elements 5 and 6 between the other end portions of the thermoelectric elements 5 and 6 and the corresponding electrodes 14 disposed on the lower surface of the second substrate 15. 12 is arranged. As the conductive member 12, for example, a metal piece in which fine metal wires are knitted in a mesh shape so as to be deformable in the thickness direction is used. This deformation may be elastic deformation or plastic deformation. For example, a copper thin wire is used.

  By using the conductive member 12 in this way, the deformation and movement of the thermoelectric elements 5 and 6 during operation in a high temperature environment are absorbed by the conductive member 12, and damage to the thermoelectric elements 5 and 6 is prevented. Is possible. Moreover, since the variation in the height of the thermoelectric elements 5 and 6 is absorbed by the conductive member 12, it is possible to reduce processes such as selection and verification for each height.

  The electrode member 13 disposed between the electrode 14 disposed on the second substrate 15 and the conductive member 12 has a bathtub-like box structure formed so as to cover the conductive member 12. By forming the electrode member 13 in a bathtub shape, the conductive member 12 and the thermoelectric elements 5 and 6 are prevented from being detached from the electrode member 13, and the bottom surface portion forming the plane of the electrode member 13 is formed on the second substrate 15. Since it is opposed to the electrode 14 disposed, it is possible to increase the contact area as compared with the case where the conductive member 12 having a mesh structure is brought into direct contact with the electrode 14 disposed on the second substrate 15. The endothermic efficiency can be increased.

  The lid portion 2 is provided with a bent portion that bends in the direction in which pressure is applied, inside the joint portion with the frame portion 4. By giving elasticity to the lid portion 2 by this bent portion, assembly when the lid portion 2 is welded to the frame portion 4 while being pressed against the second substrate 15 is facilitated.

  Further, in order to improve the workability of joining the frame portion 4 and the lid portion 2, a folded portion that folds outward is provided at a portion joined to the lid portion 2 of the frame portion 4. The folded area secures a bonding area between the lid portion 2 and the frame portion 4. Furthermore, by forming the metal film 16 between the lid 2 and the second substrate 15, the heat absorption efficiency of absorbing the heat supplied to the lid 2 from the outside by the thermoelectric elements 5 and 6 is increased.

  Then, an example of the manufacturing process of the thermoelectric conversion apparatus 1 is demonstrated.

  First, as shown in the first process diagram of FIG. 5, a predetermined number of thermoelectric elements 5 and 6 are arranged on the jig substrate 30 at predetermined intervals and temporarily fixed. As a temporary fixing method, for example, a groove for fitting a thermoelectric element into the jig substrate 30 is provided, or an adhesive substance is provided on the surface of the jig substrate 30. Moreover, it becomes possible to arrange | position the thermoelectric elements 5 and 6 easily by using a mounter.

  Next, as shown in the second process diagram of FIG. 6, a first substrate 9 is prepared in which a plurality of electrodes 8 are arranged on one surface and metal foils 10, 18, and 11 are arranged on the other surface. The paste-like solder is printed at the positions where the thermoelectric elements are arranged on the surface of each electrode. Solder printing is performed, for example, by placing a mask provided with a corresponding hole in a portion where a thermoelectric element is disposed on an electrode and supplying solder from the mask. Thus, the solder supply efficiency is improved by using solder printing instead of supplying solder one by one to the position corresponding to the thermoelectric element on the electrode. However, the method for supplying solder is not particularly limited.

  Next, as shown in the third step diagram of FIG. 7, the first substrate 9 after supplying the solder in FIG. 6 is reversed, and each thermoelectric element 5 arranged on the jig substrate 30 in the state of FIG. , 6 so that each solder is in contact with each corresponding thermoelectric element. Then, the solder in this state is put into a reflow furnace or the like and heated to melt the solder, and then cooled to fix the thermoelectric elements 5 and 6 and the electrodes 8 with the solder. Then, the jig substrate 30 is removed when the solder is sufficiently solidified.

  Next, as shown in the fourth step diagram of FIG. 8, the whole is inverted, and one end of the frame 4 is joined to the surface of the first substrate 9 where the electrode 8 is not provided. At the time of this joining, one end part of the frame part 4 is welded to the metal foil 11 by irradiating the joining part with laser. For this welding, for example, laser welding is used. As the material of each member, for example, copper is used for the metal foil 11 and Kovar is used for the frame portion 4. In welding in this case, one end of the frame 4 and the metal foil 11 are laser-welded with a nickel foil sandwiched between them.

  When laser welding is used for joining the first substrate 9 and the frame portion 4, there are the following advantages. For example, when the first substrate 9 and the frame portion 4 are joined by brazing, the whole is heated to a temperature higher than that of soldering. Therefore, if soldering is performed before brazing, the soldering is performed. All melt. For this reason, since it is necessary to solder the thermoelectric elements 5 and 6 after brazing the frame portion 4, the frame portion 4 becomes an obstacle during soldering, and solder printing cannot be performed. Efficiency will decrease. In this regard, when laser welding is applied to the joining of the first substrate 9 and the frame portion 4, the joining portion can be locally heated. Therefore, after the thermoelectric elements 5 and 6 are soldered, the first substrate 9 and the frame portion are joined. 4 can be joined. As a result, solder printing can be used in the soldering process of the thermoelectric elements 5 and 6, and the working efficiency can be improved.

  Next, as shown in the fifth step diagram of FIG. 9, a second substrate 15 having a plurality of electrodes 14 provided on the surface is prepared, and each electrode 14 on the second substrate 15 is connected to each thermoelectric element 5, 6. The second substrate 15 is disposed on each of the thermoelectric elements 5 and 6 so as to correspond to the other end of each. Each thermoelectric element 5, 6 is sandwiched between the electrode 8 provided on the first substrate 9 and the electrode 14 provided on the second substrate 15, and is electrically connected in series. At this time, the conductive member 12 and the electrode member 13 are sandwiched between the electrodes 14 and the other end portions of the thermoelectric elements 5 and 6.

  Next, in the sixth step, the lid portion 2 is disposed so as to cover the second substrate 15 from the outside on the surface side where the electrode 14 of the second substrate 15 is not provided, and the second substrate 15, the first substrate 9, The other end portion of the frame portion 4 and the lid portion 2 are joined so that pressure is applied between them. For this joining, for example, laser welding is used. In this way, the box structure shown in FIG. 1 is obtained.

  Finally, the thermoelectric conversion device having an airtight sealing structure is obtained by leaving it in a reduced-pressure atmosphere and melting and closing a through-hole previously provided in the lid 2 with a laser.

  Therefore, according to the present embodiment, one end portion of the frame portion 4 is joined to the surface of the first substrate 9 where the electrode 8 is not provided, so that the thermoelectric elements 5 and 6 joined to the electrode 8 are joined. The installation density of can be improved. Moreover, since it becomes possible to enlarge the joining area of the one end part of the frame part 4 and the 1st board | substrate 9, the joining intensity | strength of the frame part 4 and the 1st board | substrate 9 can be raised, and the airtight inside an apparatus is carried out. Can be improved. Furthermore, since it is possible to secure a wide bonding area between the second metal foil 11 and the first substrate 9, the brazing strength between the second metal foil 11 and the first substrate 9 can be increased, Can also improve the airtightness inside the apparatus.

  According to the present embodiment, the total thickness of the one end portion of the frame portion 4 and the second metal foil 11 is made thinner than the thickness of the first metal foil 10 so that the first metal foil 10 is in contact with the outside. On the other hand, the one end of the frame portion 4 does not come into contact, so that an increase in the amount of heat flowing out from the lid portion 2 to the frame portion 4 can be prevented, and a decrease in thermoelectric conversion efficiency can be prevented.

  According to the present embodiment, after soldering one end of the corresponding thermoelectric elements 5 and 6 on the plurality of electrodes 8, the electrode 8 of the first substrate 9 is provided on one end of the frame 4. By joining to the non-surface, the frame 4 does not get in the way during soldering, so solder printing can be applied and the solder supply efficiency can be improved.

  In each of the above-described embodiments, the thermoelectric conversion device that converts the heat supplied to the lid 2 into electricity has been described as an example, but the present invention can also be applied to a thermoelectric conversion device that converts electricity into heat. It is.

It is sectional drawing which shows the structure of the thermoelectric conversion apparatus in one embodiment. It is a perspective sectional view when the thermoelectric conversion device is viewed from below. It is an enlarged view which shows the detailed structure of the lower right part in FIG. 1 of the said thermoelectric conversion apparatus. It is an enlarged view which shows another structure of the lower right part in FIG. 1 of the said thermoelectric conversion apparatus. It is a figure which shows the 1st process at the time of manufacturing the said thermoelectric conversion apparatus. It is a figure which shows the 2nd process at the time of manufacturing the said thermoelectric conversion apparatus. It is a figure which shows the 3rd process at the time of manufacturing the said thermoelectric conversion apparatus. It is a figure which shows the 4th process at the time of manufacturing the said thermoelectric conversion apparatus. It is a figure which shows the 5th process at the time of manufacturing the said thermoelectric conversion apparatus.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Thermoelectric converter, 2 ... Cover part, 4 ... Frame part, 5 ... P-type thermoelectric element, 6 ... N-type thermoelectric element, 8 ... Electrode, 9 ... 1st board | substrate, 10 ... 1st metal foil, 11 ... 1st 2 metal foil, 12 ... conductive member, 13 ... electrode member, 14 ... electrode, 15 ... second substrate, 16 ... metal film, 18 ... metal foil, 20 ... brazing material, 30 ... jig substrate

Claims (3)

A first substrate and a second substrate each having a plurality of electrodes on the surface;
A plurality of thermoelectric elements disposed between the first substrate and the second substrate such that one end corresponds to the electrode of the first substrate and the other end corresponds to the electrode of the second substrate;
A lid disposed on the side of the second substrate not provided with the electrode;
A frame part in which one end is joined to the surface on which the electrode of the first substrate is not provided and the other end is joined to the lid so as to press the lid against the first substrate ;
A first metal foil is disposed on the surface of the first substrate where no electrode is provided,
One end portion of the frame portion is bonded to the first substrate via the second metal foil,
The thermoelectric conversion device characterized in that the thickness of the one end of the frame and the second metal foil is made thinner than the thickness of the first metal foil . The thermoelectric conversion device according to claim 1 , wherein the lid portion is provided with a bent portion that is bent in the pressing direction on the inner side of a joint portion with the frame portion . Placing solder for joining a plurality of thermoelectric elements on a plurality of electrodes on a first substrate;
Soldering one end of the corresponding thermoelectric element on the plurality of electrodes;
Bonding one end of the frame to the surface of the first substrate on which the electrode is not provided;
Disposing the second substrate such that the plurality of electrodes on the second substrate correspond to the other ends of the plurality of thermoelectric elements, respectively.
A step of disposing a lid on the outside of the second substrate, and joining the other end of the frame and the lid so as to press the second substrate against the first substrate ;
The manufacturing method of the thermoelectric conversion apparatus characterized by having.

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