JP2010225609A - Thermoelectric conversion element - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain high response while maintaining satisfactory strength in a thermoelectric conversion element. <P>SOLUTION: The thermoelectric conversion element includes an insulating substrate 2, and a plurality of pairs of first conductor films 4A and second conductor film 4B mutually patterned like a belt on the surface of the insulating substrate 2 directly or through an insulating layer 3 by p-type thermoelectric material and an n-type thermoelectric material, and electrically connected in series by being alternately joined at their end parts. The first conductor films 4A and the second conductor films 4B are extendedly placed side by side between both side end parts 2a, 2b with the end parts disposed in the vicinity of both side end parts 2a, 2b of the insulating substrate 2, and a thin end portion 7 made thinner than other portions is formed in the vicinity of both side end parts 2a, 2b on the back of the insulating substrate 2. <P>COPYRIGHT: (C)2011,JPO&INPIT

Description

  The present invention relates to a thin thermoelectric conversion element applicable to a thermoelectric power generation element, a thermopile, and the like.

  Thermoelectric conversion elements are known as elements such as thermoelectric power generation (thermoelectric power generation element) by the Seebeck effect, thermoelectric cooling (Peltier element) by the Peltier effect, and thermopile (thermoelectric stack). These thermoelectric conversion elements have a structure in which a p-type thermoelectric material and an n-type thermoelectric material are connected to each other. A general thermoelectric conversion element has a structure in which a block body of p-type thermoelectric material and a block body of n-type thermoelectric material are arranged on a substrate and connected in series, but in this case, fine precision processing is difficult. It was difficult to reduce the size and thickness.

  For this reason, conventionally, as described in Patent Document 1, for example, there is a thermoelectric conversion element in which a p-type thermoelectric material and an n-type thermoelectric material are formed in a thin film shape on the surface of a substrate by a physical vapor deposition technique such as sputtering. Proposed. In such a thermoelectric conversion element, since a thin thermoelectric material is formed, it is possible to form a thermoelectric material having a fine and complicated pattern, and an extremely small and thin thermoelectric conversion element can be realized.

Further, as described in Patent Document 2, a part of the pattern of the p-type FeSi ₂ film is covered with an insulating film so as to be exposed, and the n-type FeSi ₂ film is covered so as to be joined to the exposed part. A method of manufacturing a thermopile to be worn has been proposed. In this manufacturing method, as a result of increasing the film thickness, the internal specific resistance can be lowered, and the S / N ratio as a thermal sensor can be improved.

Japanese Patent Laying-Open No. 2005-277343 (Claims) JP-A-5-41545 (Claims)

The following problems remain in the conventional technology.
That is, in the above conventional technique, a single layer substrate made of a ceramic material or the like is used as a base material for forming a thin film. However, the thicker the substrate, the larger the heat capacity, and there is a disadvantage that the responsiveness is lowered. For this reason, if the substrate is made thinner, the responsiveness is improved, but the overall strength is lowered, and there is a possibility that the reliability is lowered.

  This invention is made | formed in view of the above-mentioned subject, and it aims at providing the thermoelectric conversion element which can obtain high responsiveness, maintaining favorable intensity | strength.

  The present invention employs the following configuration in order to solve the above problems. That is, the thermoelectric conversion element of the present invention is formed in a strip pattern with an insulating substrate and a p-type thermoelectric material and an n-type thermoelectric material directly on the surface of the insulating substrate or via an insulating layer. A plurality of pairs of first conductor films and second conductor films that are alternately joined at a portion and are electrically connected in series, and the first conductor film and the second conductor film However, the end portions are arranged in the vicinity of both side end portions of the insulating substrate and are arranged to extend between the both side end portions, on the back surface of the insulating substrate and in the vicinity of both side end portions, An end thin portion having a thickness thinner than other portions is formed.

  In this thermoelectric conversion element, the thickness is thinner than the other portions on the back surface of the insulating substrate and in the vicinity of both end portions, that is, immediately below both end portions of the first conductor film and the second conductor film. Since the end thin portion is formed, the vicinity of both side end portions which are the low temperature portion or the high temperature portion has a small heat capacity due to the end thin portion, so that high responsiveness can be obtained. Further, by thinning only the thin end portion, it is possible to maintain good strength as the whole insulating substrate.

Further, the thermoelectric conversion element of the present invention is characterized in that a plurality of the first conductor films and the second conductor films are laminated via an insulating layer.
That is, in this thermoelectric conversion element, a plurality of first conductor films and a plurality of second conductor films are laminated via an insulating layer, so that a large number of thermocouple portions are connected in series with a multilayer structure even in a small space. And high electromotive force can be obtained. In particular, a clearer temperature difference can be obtained by forming the insulating layer with a material having low thermal conductivity such as a ZrO ₂ film.

The present invention has the following effects.
That is, according to the thermoelectric conversion element according to the present invention, the end thin portion having a thickness thinner than other portions is formed on the back surface of the insulating substrate in the vicinity of both end portions. High responsiveness can be obtained because the vicinity of both side end portions, which are considered to be part or high temperature portion, has a small heat capacity due to the end thin portion. Further, by laminating a plurality of first conductor films and second conductor films with an insulating layer interposed therebetween, a large number of thermocouple portions can be connected in series, and a high electromotive force can be obtained.

It is a perspective view which shows one Embodiment of the thermoelectric conversion element which concerns on this invention. In this embodiment, it is the disassembled perspective view which shows the thermoelectric conversion element, and the perspective view seen from the back surface side. It is AA arrow sectional drawing of FIG. In this embodiment, it is an enlarged plan view of the principal part which shows joining of the 1st conductor film and the 2nd conductor film. In this embodiment, it is an expanded sectional view of the principal part which shows the manufacturing method of a thermoelectric conversion element in process order.

  Hereinafter, a first embodiment of a thermoelectric conversion element according to the present invention will be described with reference to FIGS. 1 to 5. In each drawing used in the following description, the scale is appropriately changed so that each member can be recognized or easily recognized.

  The thermoelectric conversion element 1 of this embodiment is applied to a thermoelectric power generation element, a temperature sensor, and the like. As shown in FIGS. 1 to 4, an insulating substrate 2 and a surface of the insulating substrate 2 are provided. A plurality of pairs of first conductive layers which are patterned in a strip shape with a p-type thermoelectric material and an n-type thermoelectric material directly or through an insulating layer 3 and are alternately joined at the ends and electrically connected in series. A body film 4A and a second conductor film 4B, and a pair of lead wires 5 connected to the ends of the first conductor film 4A and the second conductor film 4B connected in series are provided.

  Each of the first conductor film 4A and the second conductor film 4B has an end portion disposed in the vicinity of both end portions 2a and 2b of the insulating substrate 2 and extends between the end portions 2a and 2b. Are lined up. Also, as shown in FIG. 4, the first conductor film 4A and the second conductor film 4B joined to each other at the end portions are such that the end portion of one conductor film is bent in an L shape and the other is The junction 4a is formed so as to overlap the end of the conductive film.

  In other words, the first conductor film 4A and the second conductor film 4B are connected to each other at the joint portion 4a at the end portion to constitute one thermocouple portion. In addition, the first conductor film 4A and the second conductor film 4B are arranged in a comb shape as a whole by being alternately connected and folded, and the plurality of thermocouple portions are repeatedly connected in series. Configured. Increasing the number of repetitions of the pattern of the thermocouple portion by the first conductor film 4A and the second conductor film 4B (the number of connections between the first conductor film 4A and the second conductor film 4B). The sensitivity can be improved.

In the first conductor film 4A and the second conductor film 4B, for example, both a p-type thermoelectric material and an n-type thermoelectric material are formed of a FeSi ₂ -based thermoelectric material. For example, a known Bi—Te thermoelectric material, Mg—Si thermoelectric material, Mn—Si thermoelectric material, and oxide thermoelectric material may be used in addition to the FeSi ₂ thermoelectric material.

A plurality of first conductor films 4A and second conductor films 4B are stacked with an insulating layer 3 interposed therebetween. The insulating layer 3 is preferably made of a material having low thermal conductivity. In this embodiment, a ZrO ₂ film is employed. The insulating layer 3 of each layer is the first conductor film 4A or the second conductor except for a part of the folded portion (joint part 4a) between the first conductor film 4A and the second conductor film 4B. The surface of the film 4B and the entire insulating substrate 2 are covered.

  The first conductor film 4A and the second conductor film 4B of the first layer L1, which is the lowermost layer, have one end connected to one of the lead wires 5 and the other end laminated on one layer. The first conductor film 4A and the second conductor film 4B of the layer L2 are connected to one end. The other ends of the first conductor film 4A and the second conductor film 4B of the second layer L2 are further formed of the first conductor film 4A and the second conductor film 4B of the layer laminated thereon. Connected to one end.

  The other ends of the first conductor film 4A and the second conductor film 4B of the uppermost layer Ln are connected to the other lead wire 5. As described above, the first conductor film 4A and the second conductor film 4B are alternately connected in series between the upper and lower layers. In FIG. 3, only the three layers of the first conductor film 4A and the second conductor film 4B are illustrated in a simplified manner.

The insulating substrate 2 is made of a ceramic material such as an alumina substrate, for example.
Further, it is a back surface of the insulating substrate 2 and in the vicinity of both side end portions 2a and 2b, that is, immediately below both end portions of the first conductor film 4A and the second conductor film 4B, and is thinner than other portions. A pair of thin end portions 7 are formed.
These end thin portions 7 are rectangular holes extending along the side end 2a or the side end 2b.
The lead wire 5 is connected to a current measuring device or a voltage measuring device (not shown).

  Next, the manufacturing method of the thermoelectric conversion element 1 of this embodiment is demonstrated with reference to FIG.4 and FIG.5.

First, as the insulating substrate 2, as shown in FIG. 5A, for example, an alumina substrate having a predetermined constant thickness is used, and as shown in FIG. 5B, the upper surface of the insulating substrate 2 is used. A p-type FeSi ₂ film, for example, is deposited as a first conductor film 4A on the entire surface to a predetermined thickness by sputtering. Further, as shown in FIG. 5C, the first photoresist film 11 having a predetermined pattern is formed by depositing the first photoresist film 11 on the first conductor film 4A, exposing the first photoresist film 11 and exposing the same. To do.

Next, as shown in FIG. 5D, the first conductive film in a portion other than the base of the first photoresist film 11 is selectively etched with an etching solution such as HF + HNO ₃ system or HF + H ₂ SO ₄ system. The body membrane 4A is removed. As shown in FIG. 5E, the first photoresist film 11 is further removed to form a pattern of the first conductor film 4A on the insulating substrate 2.

Next, as shown in FIG. 5 (f), the first conductor film 4A is covered with a second photoresist film 12, exposed and etched to form a part on the first conductor film 4A. The second photoresist film 12 having a predetermined pattern is left. Further, as shown in FIG. 5G, a ZrO ₂ film is deposited as the insulating layer 3 so as to cover the whole of the insulating substrate 2, the first conductor film 4A, and the second photoresist film 12. . Then, as shown in FIG. 5H, a part of the pattern of the first conductor film 4A is exposed by peeling the second photoresist film 12 together with a part of the insulating layer 3 by a lift-off method. Exposed as part 4b.

Next, as shown in FIG. 5I, the second conductor film 4B is deposited by sputtering or the like so as to cover the exposed portion 4b of the first conductor film 4A and the entire insulating layer 3. . Further, as shown in FIG. 5J, a third photoresist film 13 having a predetermined pattern is deposited on the second conductor film 4B. Then, as shown in FIG. 5 (k), the second conductor film 4B other than the base of the third photoresist film 13 is selectively etched with an etchant such as HF + HNO ₃ . Further, as shown in FIG. 5L, the third photoresist film 13 is removed. As a result, a part of the first conductor film 4A (exposed part 4b) and a part of the second conductor film 4B are joined to form a joined part 4a.

Next, annealing is performed at 400 to 900 ° C. in order to crystallize the first conductor film 4A and the second conductor film 4B. This annealing increases the thermoelectromotive force.
Further, the steps shown in FIGS. 5F to 5L in the lithography process are repeated for each layer, and the first conductor film 4A and the second conductor film 4B are alternately patterned. A plurality of layers having a plurality of thermocouple portions electrically connected in series are stacked by sandwiching the insulating layer 3 except for the joint portion 4a.

Next, after each thin film is formed, as shown in FIG. 3, a metal mask having a predetermined pattern is arranged on the back surface of the insulating substrate 2, and in the vicinity of both end portions 2a and 2b, that is, the first conductor film 4A. A pair of rectangular end thin portions 7 that are thinned to a predetermined thickness are formed by blasting just below both ends of the second conductor film 4B.
And the thermoelectric conversion element 1 is produced by soldering the lead wire 5 as an electrode part to the terminal of the connected 1st conductor film 4A and 2nd conductor film 4B.

  Thus, in the thermoelectric conversion element 1 of the present embodiment, it is the back surface of the insulating substrate 2 and in the vicinity of both side end portions 2a and 2b, that is, both end portions of the first conductor film 4A and the second conductor film 4B. Since the end thin part 7 having a thickness smaller than that of the other part is formed immediately below the two sides 2a and 2b, which are the low temperature part or the high temperature part, the end thin part 7 High response can be obtained by having a small heat capacity. Further, by thinning only the thin end portion 7 partly, the insulating substrate 2 as a whole can maintain good strength.

In addition, since a plurality of first conductor films 4A and second conductor films 4B are laminated via the insulating layer 3, a large number of thermocouple portions can be connected in series with a multilayer structure even in a small space. High electromotive force can be obtained. In particular, a clearer temperature difference can be obtained by forming the insulating layer 3 with a material having low thermal conductivity such as a ZrO ₂ film.

  The technical scope of the present invention is not limited to the above embodiment, and various modifications can be made without departing from the spirit of the present invention.

  DESCRIPTION OF SYMBOLS 1 ... Thermoelectric conversion element, 2 ... Insulating substrate, 2a, 2b ... Both ends of insulating substrate, 3 ... Insulating layer, 4A ... 1st conductor film, 4B ... 2nd conductor film, 7 ... End Thin part

Claims (2)

An insulating substrate;
A plurality of p-type thermoelectric materials and n-type thermoelectric materials that are patterned in a band shape on the surface of the insulating substrate directly or through an insulating layer, and are alternately joined at the ends and electrically connected in series. A pair of first conductor film and second conductor film,
The first conductor film and the second conductor film are arranged such that the end portions are arranged in the vicinity of both end portions of the insulating substrate and extend between the both end portions;
A thermoelectric conversion element characterized in that an end thin portion having a thickness thinner than other portions is formed in the vicinity of both side end portions on the back surface of the insulating substrate. In the thermoelectric conversion element according to claim 1,
A thermoelectric conversion element, wherein a plurality of the first conductor films and the second conductor films are laminated via an insulating layer.

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