JP2016207933A - Thermoelectric transducer and manufacturing method thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a thermoelectric transducer with which a plurality of thermoelectric conversion units are formed in series connection on a substrate, and which has a height difference equal to or greater than thickness of a thermoelectric conversion layer between a heat absorption side and a heat radiation side, is capable of obtaining a high power generation performance even if used without being stood, and can be stably installed on a planar heating device only with a substrate on which the thermoelectric conversion units are formed.SOLUTION: A thermoelectric transducer 1 comprises a substrate 2 and a plurality of thermoelectric conversion units 10. A cross-sectional shape of a unit formed part 21 is formed from a projection 211, a first low surface part 212 and a second low surface part 213 at both sides of the projection. A non-formed part 22 in which no thermoelectric conversion unit is formed is located at a position lower than an apex 211a of the projection 211. The thermoelectric conversion unit 10 includes a first layer 31 from the first low surface part 212 of the unit formed part 21 to the apex 211a, and a second layer 32 from the apex 211a to the second low surface part 213. At least one of the first layer 31 and the second layer 32 are formed from a thermoelectric conversion material.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a thermoelectric conversion element and a manufacturing method thereof.

  A thermoelectric conversion element is an element which can mutually convert heat energy and electric energy. By installing the thermoelectric conversion element in an environment where a temperature difference occurs between both ends, electric power can be extracted from the thermoelectric conversion element without the need for a movable part. For example, electrical energy can be generated from exhaust heat. Therefore, the power generation technology using the thermoelectric conversion element is highly expected as an energy harvesting technology for recovering and using unused energy around us.

  If the thermoelectric conversion element can be used as, for example, a distributed self-supporting power source, it can be used as a power source for large-scale sensor networks, wearable electronics, and the like. In particular, when a thermoelectric conversion material made of an organic material is used, the thermoelectric conversion layer can be formed with a printed pattern, so that weight reduction, cost reduction, and high output due to a large area are possible. In this case, in order to maintain the flatness of the thermoelectric conversion element unit, the temperature difference is generally given in a direction perpendicular to the unit substrate.

  As an example of a thermoelectric conversion element having a thermoelectric conversion layer as a print pattern, a thermoelectric power generation element disclosed in Patent Document 1 can be given. In the thermoelectric conversion element (thermoelectric power generation element) of Patent Document 1, a plurality of thermoelectric conversion layers (thermoelectric conversion units) formed of a print pattern are formed on a corrugated substrate (base material) in which a bottom portion and a top portion are alternately repeated. A plurality of thermoelectric conversion layers are connected in series. Each thermoelectric conversion layer is formed on one of a pair of inclined surfaces of one convex portion or concave portion constituting the corrugation of the substrate, and is not formed on the other.

  In the thermoelectric conversion element of Patent Document 1, the bottom is the heat absorption side and the top is the heat dissipation side, and power is generated by the temperature difference between the bottom and the top. Further, since the substrate is formed in a corrugated shape, a large temperature difference can be obtained as the distance between the heat absorption side and the heat dissipation side increases. On the other hand, in a thermoelectric conversion element having a substrate without unevenness, a sufficient temperature difference cannot be obtained in a state where the substrate is held horizontally.

International Publication 2013/114854 Pamphlet

  In the thermoelectric conversion element of Patent Document 1, not only the portion where the thermoelectric conversion layer is formed, but also the portion where the thermoelectric conversion element is not formed, the cross-sectional shape of the entire substrate is a waveform. For this reason, when a large height difference is provided between the bottom and the top, it is necessary to provide a reinforcing material for maintaining the shape in the lower space of the convex portion of the substrate. In addition, in order to stably install on a flat heating device such as a hot plate, a support base material for mounting and fixing a plurality of bottom portions of the substrate is further required.

  An object of the present invention is that a plurality of thermoelectric conversion units are formed in series connection on a substrate, have a difference in height over the thickness of the thermoelectric conversion layer between the heat absorption side and the heat dissipation side, and are high even when used without standing It is an object to provide a thermoelectric conversion element that has a power generation performance and can be stably installed on a planar heating device only by a substrate on which a thermoelectric conversion unit is formed.

In order to solve the above problems, a first aspect of the present invention provides a thermoelectric conversion element having the following configurations (1) to (4).
(1) It has a substrate and a plurality of thermoelectric conversion units formed on the substrate.
(2) The cross-sectional shape of the unit forming portion on which the thermoelectric conversion unit of the substrate is formed includes a convex portion and a first low surface portion and a second low surface portion that are lower than the convex portions on both sides thereof. The non-formation part in which the said thermoelectric conversion unit of the said board | substrate is not formed exists in the position lower than the top part of the said convex part.

(3) The thermoelectric conversion unit has a first layer extending from the first low surface portion of the unit forming portion to the top of the convex portion, and a second layer extending from the top to the second low surface portion. At least one of the first layer and the second layer is made of a thermoelectric conversion material. The first layer and the second layer are made of the same material or different materials.
(4) The plurality of thermoelectric conversion units are connected in series. A lower wiring that connects the first layer and the second layer of the adjacent thermoelectric conversion units is formed on the first low surface portion and the second low surface portion. When the first layer and the second layer are made of different materials, an upper wiring for connecting the first layer and the second layer in the thermoelectric conversion unit is formed at the top. Connection terminals with the outside are provided at both ends of the series connection.
The thermoelectric conversion element according to the first aspect of the present invention can have the following configuration (5) in addition to the above configurations (1) to (4). The following configuration (5) is not an essential requirement of the present invention.

(5) The unit forming portion is separated from the non-forming portion within the range of the convex portion. In this case, the substrate surface, including the non-formed portion between the thermoelectric conversion units adjacent in parallel, exists in one surface (a surface including the first low surface portion and the second low surface portion). Therefore, by having the configuration (5), the effect of being able to be stably installed on a planar heating device is higher than in the case without the configuration (5).
According to a second aspect of the present invention, there is provided a method for manufacturing a thermoelectric conversion element having the above configurations (1) to (4), which includes the following steps (6) to (8).
(6) A first printing step of forming a thermoelectric conversion pattern comprising the first layer and the second layer constituting the plurality of thermoelectric conversion units on a substrate.

(7) A second printing step of forming a conductive layer pattern including the lower wiring, the connection terminal, and the upper wiring on the thermoelectric conversion pattern.
(8) A convex portion forming step in which the convex portion is formed by stretching and deforming the first layer and the second layer and a portion of the substrate where the first layer and the second layer are formed.
The thermoelectric conversion element manufactured by the method of the second aspect has the following configuration (9), the above configurations (2) to (4), and the following configuration (10).
(9) It has a substrate and a plurality of thermoelectric conversion units composed of printed patterns formed on the substrate.
(10) The lower wiring, the connection terminal, and the upper wiring are formed of a printed pattern.

  According to the present invention, a plurality of thermoelectric conversion units are formed on the substrate in series connection, and have a difference in height over the thickness of the thermoelectric conversion layer between the heat absorption side and the heat dissipation side, which is high even when used without standing. There is provided a thermoelectric conversion element that has a power generation performance and can be stably installed on a planar heating device only by a substrate on which a thermoelectric conversion unit is formed.

It is a fragmentary sectional view showing an embodiment of a thermoelectric conversion element, and shows a unit formation part of a substrate corresponding to one thermoelectric conversion unit, and a non-formation part of the both sides. It is a top view explaining the slit formation process which comprises the manufacturing method of the thermoelectric conversion element shown in FIG. It is a top view explaining the front | former stage process of the 1st printing process which comprises the manufacturing method of the thermoelectric conversion element shown in FIG. It is a top view explaining the back | latter stage process of the 1st printing process which comprises the manufacturing method of the thermoelectric conversion element shown in FIG. It is a top view explaining the 2nd printing process which comprises the manufacturing method of the thermoelectric conversion element shown in FIG. It is AA sectional drawing of FIG. It is a perspective view explaining an example of the wireless sensor transmitter using the thermoelectric conversion element of an embodiment. It is a front view which shows the example of the shape different from FIG. 1 regarding the convex part of the board | substrate which comprises the thermoelectric conversion element of embodiment.

Embodiments of the present invention will be described below. In the embodiment described below, a technically preferable limitation is made for carrying out the present invention, but the present invention is not limited to the embodiment described below.
The thermoelectric conversion element of this embodiment is a thermoelectric conversion element manufactured by performing each process shown in FIGS. FIG. 1 shows a cross section of one thermoelectric conversion unit 10 constituting the thermoelectric conversion element 1 of this embodiment.

The thermoelectric conversion element 1 includes a slit forming step shown in FIG. 2, a pre-step of the first printing step shown in FIG. 3, a post-step of the first printing step shown in FIG. 4, and a second printing step shown in FIG. The convex portion forming step from the state of FIG. 6 to the state of FIG. 1 is performed in this order.
The thermoelectric conversion element 1 includes a substrate 2 and a plurality of thermoelectric conversion units 10 each having a print pattern formed on the substrate 2. The cross-sectional shape of the unit forming portion 21 on which the thermoelectric conversion unit 10 of the substrate 2 is formed includes a convex portion 211, a first low surface portion 212, and a second low surface portion 213. The 1st low surface part 212 and the 2nd low surface part 213 are parts lower than the convex part of the both sides of the convex part 211, and are the same height as the non-formation part 22 in which the thermoelectric conversion unit 10 is not formed.

The thermoelectric conversion unit 10 includes a first layer 31 that extends from the first low surface portion 212 of the unit forming portion 21 to the top portion 211 a of the convex portion 211, and a second layer 32 that extends from the top portion 211 a to the second low surface portion 213. The unit forming portion 21 is separated from the non-forming portion 22A (see FIG. 5) on the back side of the paper surface (shown below the convex portion 211) in FIG.
The first layer 31 is made of a p-type conductive polymer (thermoelectric conversion material), and the second layer 32 is made of a cured silver paste (conductive material). Although a layer made of an n-type conductive polymer (thermoelectric conversion material) may be provided as the second layer 32, since there is no material that has stable performance at present, in this embodiment, as an alternative, a silver paste is used. A second layer 32 made of a cured product is provided. Both the first layer 31 and the second layer 32 may be formed of a conductive polymer having the same type of semiconductor characteristics. In that case, at present, a conductive polymer having p-type semiconductor characteristics is used.

As shown in FIG. 5, 14 thermoelectric conversion units 10 are formed on the substrate 2 in two columns and seven rows, and these are connected in series. Therefore, on the first low surface portion 212 and the second low surface portion 213, the first layer 31 and the second layer 32 of the adjacent thermoelectric conversion units 10 are connected via the first layer 31 and the second layer 32. Side wiring 41 is formed.
In addition, since the first layer 31 and the second layer 32 are made of different materials, the upper wiring 42 that connects the first layer 31 and the second layer 32 in the thermoelectric conversion unit 10 is located at the top 211a of the convex portion 211. Is formed. Further, both ends of the serial connection exist at one edge of the substrate 2, and connection terminals 43 with the outside are formed at each position.

In the manufacturing method of the thermoelectric conversion element 1 of this embodiment, first, as shown in FIG. 2, 28 slits 25 corresponding to each of the 14 thermoelectric conversion units 10 shown in FIG. . The slits 25 are formed with the same length as the interval between the lower wirings 41 that form a pair in the thermoelectric conversion unit 10. That is, the slit 25 is formed over the entire range where the convex portion 211 of the substrate 2 is formed.
Next, as a pre-stage process of the first printing process, as shown in FIG. 3, one first layer 31 is formed in one thermoelectric conversion unit 10 with a width between two adjacent slits 25 in each row. . In addition, the adjacent first layers 31 are arranged in positions opposite to each other in the length direction of the slits 25 in and between the two rows of the 14 thermoelectric conversion units 10. Further, the end of the first layer 31 in the direction along the slit 25 protrudes outside the slit 25.

Next, as a subsequent process of the first printing process, as shown in FIG. 4, one second layer 32 is formed in one thermoelectric conversion unit 10 with a width between two adjacent slits 25 in each row. . The second layer 32 is formed in the contact state next to the first layer 31 with the same thickness as the first layer 31.
Thus, the thermoelectric conversion pattern which consists of all the 1st layers 31 and the 2nd layers 32 which comprise the thermoelectric conversion unit 10 of 2 rows 14 pieces is formed on the board | substrate 2. FIG. In the state of FIG. 4, the portion of the substrate 2 where the first layer 31 and the second layer 32 exist is a unit forming portion, and the other portion is a non-forming portion.

Next, as a second printing step, as shown in FIG. 5, a conductive layer pattern including a lower wiring 41, a connection terminal 43, and an upper wiring 42 is formed on the thermoelectric conversion pattern shown in FIG. In this state, the thermoelectric conversion unit 10 is formed in a flat plate shape on the flat substrate 2 as shown in FIG.
Next, as a convex portion forming step, a male portion corresponding to the convex portion 211 of FIG. 1 is provided on the back surface (the surface where the thermoelectric conversion unit 10 is not formed) of the portion of the substrate 2 where the slit 25 is formed. Press the mold and pressurize. Thereby, the first layer 31 and the second layer 32 and the portion of the substrate 2 where the first layer and the second layer are formed are stretched and deformed to form the convex portion 211. In that case, the convex part 211 is formed in all the thermoelectric conversion units 10 at once by using the metal mold | die which has the male part matched with the convex part 211 of all the unit formation parts 21. FIG.

  Thus, the manufactured thermoelectric conversion element 1 is the low part 31a which is a part on the 1st low surface part 212 of the 1st layer 31, and the 2nd low surface part 213 of the 2nd layer 32 in all the thermoelectric conversion units 10. More than the thickness of the 1st layer 31 and the 2nd layer 32 between the low part 32a which is an upper part, and the high parts 31b and 32b which are the parts on the top part 211a of the 1st layer 31 and the 2nd layer 32 There is a difference in height.

Therefore, the thermoelectric conversion element 1 is placed on, for example, a hot plate while holding the non-formed portion 22 of the substrate 2 horizontally, and the low portion 31 a of the first layer 31 and the low portion of the second layer 32 are interposed via the substrate 2. Even when the part 32a is heated and used, high power generation performance can be obtained. Further, the substrate 2 on which the printed pattern is formed can be stably placed on the hot plate.
Furthermore, since the entire range of the convex portions 211 of all the unit forming portions 21 is separated from the non-forming portion 22A, the lower space K of all the convex portions 211 is connected for each row of the thermoelectric conversion units 10, It becomes the air flow path. Therefore, when the top portion 211a is cooled by circulating the air through the flow path formed of the lower space K during the heating by the hot plate described above, the low portions 31a and 32a and the high portions 31b and 32b of the thermoelectric conversion unit 10 are cooled. In the meantime, a larger temperature difference can be produced.

[application]
The thermoelectric conversion element 1 of the embodiment can be used as a self-supporting power source of a wireless sensor transmission device.
The wireless sensor transmission device 5 shown in FIG. 7 includes an antenna circuit 52 and a sensor terminal 53 formed on a circuit board 51, a self-supporting power source including a thermoelectric conversion element 1, a signal processing / transmission circuit 54, a voltage amplification unit / battery. 55.

  As described above, the thermoelectric conversion element 1 of the embodiment includes the thermoelectric conversion layer (the first layer 31 and the first layer 31 and the heat absorption portion) 31a and 32a and the high portions (heat dissipation portions) 31b and 32b of the thermoelectric conversion unit 10. Since it has a height difference equal to or greater than the thickness of the second layer 32), it is possible to supply sufficient power to drive the wireless sensor even when the thermal energy applied to the heat absorbing portion is small. Therefore, the wireless sensor transmission device 5 using the thermoelectric conversion element 1 of the embodiment as a power source can be used as a self-supporting wireless sensor transmission device that can always operate even in a place where there is no illumination where a solar cell cannot be used.

[About convex shape]
FIG. 8 shows a plurality of examples of the shape of the convex portion constituting the cross-sectional shape of the unit forming portion 21 of the substrate 2.
8A is a pair of inclined surfaces connecting a top portion 27 formed of an arc surface facing the same plane 26 as the back surface of the substrate 2, and both ends of a straight line forming the plane 26 and both ends of the arc forming the top portion 27. 28. The boundary between the top 27 and the inclined surface 28 is rounded.
The convex portion in FIG. 8B is a pair of slopes connecting a top portion 27 formed of a plane facing the same plane 26 as the back surface of the substrate 2, and both ends of a straight line forming the plane 26 and both ends of a straight line forming the top portion 27. Surface 28. The boundary between the top 27 and the inclined surface 28 is rounded.

The convex portion in FIG. 8C connects a top portion 27 formed of a plane facing the same plane 26 as the back surface of the substrate 2, and both ends of a straight line forming the plane 26 and both ends of a straight line forming the top portion 27. And a pair of vertical surfaces 29 perpendicular to each other. The boundary between the top 27 and the vertical surface 29 is rounded.
The convex portion in FIG. 8D is formed of an arcuate surface 27A that faces the same plane 26 as the back surface of the substrate 2 and is joined to both ends of a straight line that forms the plane 26. The position farthest from the flat surface 26 of the circular arc surface 27A is the top.

[About materials]
<Thermoelectric conversion material>
As the thermoelectric conversion material, a conductive polymer or CNT (carbon nanotube) can be preferably used. Depending on the type of the conductive polymer, a binder such as a thermosetting resin necessary for molding, a conductive material A CNT (carbon nanotube) dispersion for increasing the viscosity and a polar high-boiling solvent such as ethylene glycol, dimethyl sulfoxide, n-methylpyrrolidone or dimethylformamide, polyethylene glycol, diethylene glycol monomethyl ether can be added.
Note that the thermoelectric conversion material is not limited as long as the material can follow the deformation of the substrate, and an inorganic material or a mixed material of an organic substance and an inorganic substance can also be used. Generally, when the breaking strain of the thermoelectric conversion material is 10% or more, it is easy to follow the deformation of the substrate.

<Example of thermoelectric conversion material made of conductive polymer>
As the p-type conductive polymer (conductive polymer having p-type semiconductor characteristics), a polymer compound having a conjugated molecular structure (conjugated polymer) can be used.
Conjugated polymers include polythiophene compounds (breaking strain 10-20%), polypyrrole compounds (breaking strain 20%), polyaniline compounds (breaking strain 35%), and polyacetylene compounds (breaking strain 800%). , Poly (p-phenylene) compound, poly (p-phenylene vinylene) compound (PPV compound, 5% strain at break after 150 ° C. heat-stretching treatment), poly (p-phenylene ethynylene) compound (break strain) 2.5%), poly (p-fluorenylene vinylene) compound (breaking strain 2.5%), polyacene compound (breaking strain 1%), and polyphenanthrene compound (breaking strain 1%).

Moreover, the conjugated polymer which has a repeating unit which consists of a derivative | guide_body in which the substituent was introduce | transduced into the monomer of the said high molecular compound is also mentioned.
As the n-type conductive polymer (conductive polymer having n-type semiconductor characteristics), a polymer compound having a conjugated molecular structure can be given, but many unstable substances are present.

<About the first layer and the second layer>
At least one of the first layer and the second layer is made of a thermoelectric conversion material, and the first layer and the second layer are made of the same material or different materials. When the first layer and the second layer are made of different materials, an upper wiring that connects the first layer and the second layer in the thermoelectric conversion unit is formed on the top of the convex portion. When the first layer and the second layer are made of the same material, the upper wiring is not necessary.
That is, when the first layer and the second layer are made of different materials, the combination of materials is p-type thermoelectric material and n-type thermoelectric material, p-type thermoelectric material and conductive material (no thermoelectric conversion function), n-type thermoelectric material. And conductive materials (without thermoelectric conversion function). However, as described above, many n-type thermoelectric materials (n-type conductive polymers) made of conductive polymers are unstable.

<Board>
The type of the substrate is not particularly limited, but it is preferable to use a substrate (breaking strain of 50% or more) that is not easily affected by the formation of the electrode or the thermoelectric conversion layer and that is not easily broken during deformation. From the viewpoint of cost and flexibility, a plastic film is preferable. Polyethylene terephthalate, polyethylene isophthalate, polyethylene naphthalate, polybutylene terephthalate, poly (1,4-cyclohexylenedimethylene terephthalate), polyethylene-2,6-phthalenedicarboxy Examples thereof include polyester film such as polyester film obtained by polymerization of rate, bisphenol A with iso and terephthalic acid, polycycloolefin film, polyimide film, polycarbonate film, polyether ether ketone film, polyphenyl sulfide film and the like.
Of these, commercially available polyethylene terephthalate (PET), polyethylene naphthalate (PEN), various polyimides and polycarbonate films are preferred from the viewpoints of availability, heat resistance of 100 ° C. or higher, processability, economy and effects. Considering the printing process, for example, a sheet subjected to one-side easy adhesion processing is preferable.

[About preferred embodiments]
The thermoelectric conversion element according to the first aspect of the present invention preferably further has at least one of the following configurations (a) to (e).
(a) At least one of the first layer and the second layer is made of a conductive polymer.
(b) At least one of the first layer and the second layer is a polythiophene compound, a polypyrrole compound, a polyaniline compound, a polyacetylene compound, a poly (p-phenylene) compound, or poly (p-phenylene vinylene). Compounds, poly (p-phenyleneethynylene) compounds, poly (p-fluorenylene vinylene) compounds, polyacene compounds, polyphenanthrene compounds, and derivatives in which substituents are introduced into the monomers of these compounds And having at least one selected from conjugated polymers having a repeating unit.

(c) The thermoelectric conversion material is a p-type conductive polymer.
(d) The substrate is made of polyethylene terephthalate film, polyethylene isophthalate film, polyethylene naphthalate film, polybutylene terephthalate film, poly (1,4-cyclohexylenedimethylene terephthalate) film, polyethylene-2,6-phthalenedicarboxylate. It consists of at least one selected from a film, a polyimide film, a polycarbonate film, a polyether ether ketone film, and a polyphenyl sulfide film.

(e) The printed pattern of the thermoelectric conversion element is covered with a protective layer (for example, a layer obtained by applying and curing a coating agent made of a synthetic resin).
The method for manufacturing a thermoelectric conversion element according to the second aspect of the present invention preferably further has the following configuration (f).
(f) forming a slit corresponding to the thermoelectric conversion unit within a range of forming the convex portion of the substrate;
As a third aspect of the present invention, there is a power supply for a wireless sensor provided with the thermoelectric conversion element of the first aspect.
As a fourth aspect of the present invention, a self-supporting power source comprising the thermoelectric conversion element of the first aspect, a signal processing / transmission circuit, a voltage amplification unit / battery, and a circuit board on which an antenna circuit and a sensor terminal are formed, The wireless sensor which has is mentioned.

[About thermoelectric conversion materials]
In Samples Nos. 1 to 3 and Sample No. 5, “Clevios PH1000 (aqueous dispersion)” of Heraeus Co., Ltd., which is a coating agent containing a polythiophene compound, was used as the material of the first layer 31. The polythiophene compound is a p-type conductive polymer, and the main component of this coating agent is “poly (3,4-ethylenedioxythiophene): polystyrene sulfide”.

Cellulose nanofibers (manufactured by Chuetsu Pulp Co., Ltd., maximum width 500 nm or less, average width 50 nm or less, average fiber length 0.5 μm, polymerization degree 350) are added in an amount of 5 mass% with respect to the active ingredient of PH1000, and ethylene glycol is added to PH1000. After adding to 5% by volume, the mixture was heated with stirring to evaporate the water, thereby obtaining a gel-like p-type thermoelectric conversion material.
In Sample No. 4 and Sample No. 6, a poly (p-phenylene vinylene) -based compound (PPV-based compound) was used as the material for the first layer 31. The preparation method is as follows. A monomer solution was obtained by dissolving 10 g of monomer p-xylylene bis (tetrahydrothiophenium chloride) in 200 ml of water, and the monomer solution was cooled to 0 ° C. Separately from this, an aqueous sodium hydroxide solution having a 1.1-fold molar concentration with respect to the monomer was prepared and dropped into the monomer solution. After the dropwise addition, the polymerization liquid was obtained by further stirring for 1 hour.

  After neutralizing this polymerization solution with an aqueous hydrochloric acid solution, dialysis treatment was performed using a dialysis membrane (cellotube manufactured by Wako Pure Chemical Industries) to obtain a purified PPV precursor solution. 10 mg of carbon nanotubes (manufactured by Aldrich Co., Ltd.) was added to 10 g of the obtained PPV precursor solution, and the PPV precursor solution applicable to the substrate was prepared by performing treatment for 30 minutes in an ultrasonic bath. The PPV precursor solution thus obtained is attached to the first layer 31 forming part of the substrate 2 and then held at 50 ° C. for 12 hours, and the solvent removal step is followed by stretching at 120 ° C. The first layer 31 made of a PPV compound is formed on the substrate 2 through a stretching process and a heat treatment process at 150 ° C.

  As a material for the second layer 32, the lower wiring 41, the connection terminal 43, and the upper wiring 42, silver paste was used. The lower wiring 41, the connection terminal 43, and the upper wiring 42 were formed by screen printing. As the silver paste, for example, “Dotite FA-333” manufactured by Fujikura Kasei Co., Ltd. can be used. Further, in order to suppress silver oxidation, a carbon paste may be printed over the silver paste.

[Manufacture of thermoelectric conversion elements]
Thermoelectric conversion elements having 100 thermoelectric conversion units in a matrix of 10 columns and 10 rows were manufactured by the following method. In the embodiment, a thermoelectric conversion element having two columns and seven rows and 14 thermoelectric conversion units 10 has been described. However, in the following examples, each step is the same as that described in the embodiment except that the number of thermoelectric conversion units 10 is different. Performed in the same manner as the process.

<Sample No.1>
First, as shown in FIG. 2, the slit 25 was formed in the board | substrate 2 which consists of a 100-micrometer-thick PET film similarly to the method demonstrated in embodiment. In the embodiment, since there are 2 columns and 7 rows, there are 28 slits. In this embodiment, 20 slits 25 are formed in each column, for a total of 200 slits.

  Next, a metal mask having a thickness of 0.1 mm in which the opening pattern of the first layer 31 is alternately formed in each column and each row in the same manner as in FIG. 3 is prepared. A p-type thermoelectric conversion material was printed. Thereby, the printing pattern of the first layer 31 made of the p-type thermoelectric conversion material was formed between the slits 25 of each thermoelectric conversion unit 10 on the substrate 2. Next, the substrate 2 in this state was heated at 120 ° C. for 2 hours to dry the p-type thermoelectric conversion material. The thickness of the first layer 31 after drying was 5 μm.

  Next, the second layer 32 made of a silver paste was printed next to the first layers 31 of all the thermoelectric conversion units 10, and the silver paste was dried by heating at 120 ° C. for 2 hours. This printing was performed by screen printing. The silver paste was printed so that the second layer 32 after drying was 10 μm. Thereby, 100 thermoelectric conversion patterns composed of the first layer 31 and the second layer 32 similar to those in FIG. 4 were formed.

  Next, a conductive layer pattern composed of the lower wiring 41, the connection terminal 43, and the upper wiring 42 was formed on all the thermoelectric conversion patterns as in FIG. The conductive layer pattern was formed by screen-printing a silver paste, followed by heating at 120 ° C. for 2 hours and drying. In this state, each thermoelectric conversion unit 10 is formed in a flat plate shape on the flat plate substrate 2 as shown in FIG.

Next, all the thermoelectric conversion units 10 were made into the state shown in FIG. 1 by performing the convex part formation process described in the embodiment with respect to all the thermoelectric conversion units 10. The convex portion forming step was performed by pressing the male die against the back surface of the substrate 2 for 10 minutes (pressure forming without heating). Thereby, the protrusion height T of the convex part 211 was 1 mm. The first layer 31 and the second layer 32 were also stretched and deformed together with the substrate 2.
As shown in FIG. 1, the thermoelectric conversion element 1 obtained in this way has an air flow path in which the lower space K of the convex portion 211 is connected for each row of thermoelectric conversion units 10.

<Sample No.2>
First, without forming the slit 25 on the same substrate 2 as the sample No. 1, the thermoelectric conversion pattern composed of the first layer 31 and the second layer 32 is placed at the same position as the sample No. 1 on the substrate 2 and the sample No. The same material as 1 was used and printed in the same manner as Sample No. 1.
Next, a conductive layer pattern composed of the lower wiring 41, the connection terminal 43, and the upper wiring 42 was formed by the sample No. 1 and the method.

Next, with respect to all the thermoelectric conversion units 10, in the state which heated the board | substrate 2 at 120 degreeC, the male type | mold of the metal mold | die was pressed on the back surface of the board | substrate 2 for 10 minutes (pressurization and thermoforming).
The thermoelectric conversion element thus obtained has a convex portion similar to the convex portion 211 in FIG. 1, but the unit forming portion 21 and the non-forming portion 22A are not separated. Therefore, the boundary with the non-formation part 22A of the both sides of the thermoelectric conversion unit 10 is loose. Further, since the lower spaces of the convex portions are independent one by one, they do not have an air flow path to which the lower space K of the convex portion 211 is connected, unlike the thermoelectric conversion element of sample No. 1. In sample No. 2, the protruding height of the convex portion was set to 1 mm as in sample No. 1.

<Sample No. 3>
First, similarly to sample No. 1, the slit 25 was formed on the substrate 2. Next, the convex part 211 was formed in all the thermoelectric conversion units 10 by pressing the male mold | die on the back surface of the board | substrate 2 for 10 minutes (pressure forming without a heating). The protruding height T of the convex portion 211 was set to 1 mm as in No.1.

Next, using the same p-type thermoelectric conversion material as in sample No. 1, after printing the first layer 31 on the part from the first low surface portion 212 of all the unit forming portions 21 to the top portion 211a of the convex portion 211, Dried. This printing was performed using a metal mask having a thickness of 0.1 mm.
Next, the second layer 32 was printed on the part from the second low surface part 213 of all the unit forming parts 21 to the top part 211a of the convex part 211 using silver paste, and then dried. This printing was performed by screen printing.

Next, the lower wiring 41 and the connection terminal 43 are connected to the lower portion 31 a of the first layer 31 formed on the first lower surface portion 212 and the lower portion 32 a of the second layer 32 formed on the second lower surface portion 213. And the upper wiring 42 was printed on the high portion 31b of the first layer 31 and the high portion 32b of the second layer 32 formed on the top portion 211a of the convex portion 211. These wiring and terminals were printed by screen printing.
The thermoelectric conversion element thus obtained has a structure similar to that of the thermoelectric conversion element 1 of FIG. 1, but the first layer 31 and the second layer 32 are entirely including portions other than the low portions 31 a and 32 a. Is not stretched and deformed. For each thermoelectric conversion unit 10 in each row, there is an atmospheric flow path to which the lower space K of the convex portion 211 is connected.

<Sample No. 4>
First, the formation process of the slit 25 with respect to the board | substrate 2 was performed by the same method as sample No.1. Next, after the PPV precursor solution described above was attached to the first layer 31 forming portion of the substrate 2 by screen printing, it was held at 50 ° C. for 12 hours to remove the solvent in the PPV precursor solution layer. Next, after performing the extending | stretching process which extends the board | substrate 2 for 60 minutes at 120 degreeC, the heat processing for 60 minutes were performed at 150 degreeC. Thereby, the first layer 31 made of the PPV compound was formed on the substrate 2.

Next, the step of forming the second layer 32 and the step of forming a conductive layer were performed by the same method as Sample No. 1.
Next, the convex part formation process was performed by pressing the male mold | die of the metal mold | die on the back surface of the board | substrate 2 for 10 minutes in the state which heated the board | substrate 2 at 150 degreeC (heat press molding). Moreover, the protrusion height T of the convex part 211 was 1 mm. Along with this, the first layer 31 and the second layer 32 were also stretched and deformed together with the substrate 2.
As shown in FIG. 1, the thermoelectric conversion element 1 obtained in this way has an air flow path in which the lower space K of the convex portion 211 is connected for each row of thermoelectric conversion units 10.

<Sample No. 5 (comparative example)>
Without forming the slit 25 in the substrate 2, a metal mask thicker than sample No. 1 and the same material as sample No. 1 are used, and a thermoelectric conversion pattern consisting of the first layer 31 and the second layer 32 is 1 mm thick. The sample was printed at the same position as Sample No. 1 on the substrate 2.
Next, a conductive layer pattern including the lower wiring 41, the connection terminal 43, and the upper wiring 42 was formed by the same method as Sample No. 1.

<Sample No. 6 (comparative example)>
First, similarly to sample No. 1, the slit 25 was formed on the substrate 2. Next, the convex part formation process was performed by pressing the male mold | die of the metal mold | die on the back surface of the board | substrate 2 for 10 minutes in the state which heated the board | substrate 2 at 150 degreeC (heat press molding). The protruding height T of the convex portion 211 was set to 1 mm as in No.1.

Next, after the PPV precursor solution described above was attached to the first layer 31 forming portion of the substrate 2 by screen printing, it was held at 50 ° C. for 12 hours to remove the solvent in the PPV precursor solution layer. Next, a heat treatment was performed at 150 ° C. for 60 minutes without performing a stretching treatment. Thereby, the first layer 31 made of the PPV compound was formed on the substrate 2. Next, the formation of the second layer 32 and the conductive layer formation step were performed by the same method as Sample No. 4.
The thermoelectric conversion element thus obtained has a structure similar to that of the thermoelectric conversion element 1 of FIG. 1, but the first layer 31 and the second layer 32 are entirely including portions other than the low portions 31 a and 32 a. Is not stretched and deformed. For each thermoelectric conversion unit 10 in each row, there is an atmospheric flow path to which the lower space K of the convex portion 211 is connected.

[Breaking strain test]
Sample No. 1 and Sample No. 4 are different in the material constituting the first layer 31. The first layer 31 of sample No. 1 is made of “poly (3,4-ethylenedioxythiophene): polystyrene sulfide”, and the first layer 31 of sample No. 4 is made of a PPV compound. Test pieces corresponding to each of them, that is, test piece No. 1 in which “poly (3,4-ethylenedioxythiophene): polystyrene sulfide” is formed on a PET film and a test piece in which a PPV compound is formed on a PET film No. 4 was prepared and a tensile fracture test was conducted. As a result, the fracture strain of the thermoelectric conversion layer was 10% for test piece No. 1 and 800% for test piece No. 4.
Moreover, when the test piece No. 4 was heat-pressed under the same conditions as in the sample No. 4 to form a convex portion and then subjected to a tensile break test, the break strain of the thermoelectric conversion layer was 5%. there were.

[Evaluation of thermoelectric conversion element]
The thermoelectric conversion elements of samples No. 1 to No. 6 are placed on a hot plate at 40 ° C. while holding the non-formed portion 22 of the substrate 2 horizontally in an environment at room temperature of 25 ° C. The low part 31a of the first layer 31 and the low part 32a of the second layer 32 were heated. In this state, the voltage generated between both terminals 43 was measured with a tester.

The measured voltage was 150 mV for sample No. 1, 120 mV for sample No. 2, 120 mV for sample No. 3, 75 mV for sample No. 4, and 50 mV for sample No. 5, but for sample No. 6. The first layer 31 was broken and no electromotive force was obtained.
In addition, since the thermoelectric conversion elements of samples No. 1 to No. 4 have the convex portions 211, the temperature difference between the low portions 31a and 32a close to the hot plate and the high portions 31b and 32b far from the hot plate is large. It was.

In the thermoelectric conversion element of sample No. 2, the temperature difference between the atmosphere open side and the hot plate contact surface was 12 ° C.
In the thermoelectric conversion elements of samples No.1, No.3, and No.4, since the atmosphere flows through the flow path connected to the lower space K, the temperature difference between the open air side and the hot plate contact surface is the sample No. It was larger than 2 thermoelectric conversion elements.

In the thermoelectric conversion element of sample No. 5 that does not have the convex portion 211, the temperature difference between the air release side and the hot plate contact surface is 5 ° C. there were.
In sample No. 4, a PPV compound having a fracture strain of 10% or less was used as the thermoelectric conversion material, but a thermoelectric conversion element having the shape shown in FIG.

[Assembly of wireless sensor transmitter]
Using each of the thermoelectric conversion elements of samples No. 1 to No. 6, the wireless sensor transmission device 5 shown in FIG. 7 was assembled.
First, the signal processing / transmission circuit 54 and the voltage amplification unit / battery 55 were installed on the circuit board 51 on which the antenna circuit 52 and the sensor terminal 53 were formed. Next, the circuit board 51 in this state was attached to the upper part of the thermoelectric conversion element 1 composed of the thermoelectric conversion elements of samples No. 1 to No. 6. Next, the thermoelectric conversion element 1 was connected to the power supply controller, and the whole was stored in the housing.

[Operation of wireless sensor transmitter]
The assembled wireless sensor transmission device 5 was attached to a wall having a surface temperature of 15 ° C., and an operation test (measurement of room temperature and transmission of measurement data) was performed in an environment at room temperature of 20 ° C.
It was confirmed that the wireless sensor transmission device 5 incorporating the thermoelectric conversion elements of samples No. 1 to No. 4 can operate satisfactorily for a long time. However, in the wireless sensor transmission device 5 incorporating the thermoelectric conversion elements of Sample No. 5 and Sample No. 6, the battery was quickly worn out and the operation was stopped.

DESCRIPTION OF SYMBOLS 1 Thermoelectric conversion element 10 Thermoelectric conversion unit 2 Substrate 21 Unit formation part 211 Projection part 212 First low surface part 213 Second low surface part 22 Non-formation part 22A Non-formation part 211a Top part of convex part 31 First layer 31a First layer low Part 31b High part of the first layer 32 Second layer 32b High part of the second layer 32a Low part of the second layer 41 Lower wiring 42 Upper wiring 43 Connection terminal 5 Wireless sensor transmission device 51 Circuit board 52 Antenna circuit 53 Sensor terminal 54 Signal Processing / Transmission Circuit 55 Voltage Amplifier / Battery

Claims (3)

A substrate,
A plurality of thermoelectric conversion units formed on the substrate;
Have
The cross-sectional shape of the unit forming part in which the thermoelectric conversion unit of the substrate is formed is composed of a first low surface part and a second low surface part lower than the convex part and the convex part on both sides thereof,
The non-formation part in which the thermoelectric conversion unit of the substrate is not formed is in a position lower than the top part of the convex part,
The thermoelectric conversion unit has a first layer from the first low surface portion of the unit forming portion to the top of the convex portion, and a second layer from the top to the second low surface portion,
At least one of the first layer and the second layer is made of a thermoelectric conversion material,
The first layer and the second layer are made of the same material or different materials,
The plurality of thermoelectric conversion units are connected in series,
On the first low surface portion and the second low surface portion, a lower wiring that connects the first layer and the second layer of the adjacent thermoelectric conversion units is formed,
When the first layer and the second layer are made of different materials, an upper wiring that connects the first layer and the second layer in the thermoelectric conversion unit is formed on the top,
A thermoelectric conversion element having connection terminals to the outside at both ends of the series connection.   The thermoelectric conversion element according to claim 1, wherein the unit forming portion is separated from the non-forming portion within the range of the convex portion. It is a manufacturing method of the thermoelectric conversion element according to claim 1,
A first printing step for forming a thermoelectric conversion pattern comprising the first layer and the second layer constituting the plurality of thermoelectric conversion units on a substrate;
A second printing step of forming a conductive layer pattern composed of the lower wiring, the connection terminal, and the upper wiring on the thermoelectric conversion pattern;
A projecting portion forming step of forming the projecting portion by stretching and deforming the first layer and the second layer, and a portion of the substrate where the first layer and the second layer are formed;
The manufacturing method of the thermoelectric conversion element which has this.

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