JPH0846247A - Thermoelectric element - Google Patents

Abstract

(57) [Summary] [Object] The present invention relates to a structure of a cooling device or a thermoelectric element used for power generation by a temperature difference, and provides an element excellent in terms of manufacturability and cost. [Structure] The layer for joining the chip-shaped thermoelectric material and the substrate is made different in structure between the P-type thermoelectric material and the N-type thermoelectric material. In particular, in order to join the chip-shaped thermoelectric material and the substrate-shaped electrode, a layer made of a conductive substance such as metal is formed on the surface of the thermoelectric material by surface treatment such as plating. The P-type thermoelectric material and the N-type thermoelectric material are changed. [Effect] The color tone or element of the material forming this layer is set to P
By changing between the N-type thermoelectric material and the N-type thermoelectric material, it is possible to prevent mixing and mistake of the P-type thermoelectric material and the N-type thermoelectric material that may occur during manufacturing, and at the same time, to correct a defect that occurs during manufacturing. It can be easily corrected because the type and N type can be distinguished.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a thermoelectric element which can generate heat due to a temperature difference, or can be cooled and generate heat by passing an electric current, and has a corresponding application.

[0002]

2. Description of the Related Art A thermoelectric element is manufactured by joining a P-type thermoelectric material and an N-type thermoelectric material via a conductive electrode such as metal to form a PN junction pair. This thermoelectric element generates an electromotive force based on the Seebeck effect by applying a temperature difference between the pair of junctions, so it can be used as a power generator that utilizes the temperature difference. There is a use as a cooling device, a heating device, a precision temperature control device, etc., which utilizes the so-called Peltier effect in which heat is generated at the other joint.

A thermoelectric element is used as a thermoelectric module in which a plurality of elements are connected in series in order to improve its performance. The structure of this thermoelectric module is such that P-type and N-type thermoelectric material chips in the shape of a rectangular parallelepiped having a side of several hundred μm to several mm are sandwiched between two electrically insulating substrates such as alumina and aluminum nitride. Type thermoelectric material chip and N
At the same time that the die thermoelectric material chips are joined on the substrate by electrodes made of a conductive material such as metal, the thermoelectric material chips are connected in series by this joining.

As a method for manufacturing a thermoelectric module in which a plurality of thermoelectric elements are arranged in series as described above, a P-type and N-type thermoelectric material having a plate shape having a thickness necessary to maintain a temperature difference is formed. After cutting, the both surfaces are subjected to surface treatment such as nickel plating so that they can be soldered in order to be joined to the electrodes made of metal or the like formed on the substrate. After this,
Cut this thermoelectric material into chips of the desired size,
A method has been used in which solder for bonding is previously arranged as a wiring pattern on two insulating substrates such as alumina, which are arranged by using a jig or the like, sandwiched, and then soldered by heating to bond them. .

[0005]

However, the thermoelectric material has no significant difference in composition between the P-type and N-type as seen in Bi-Te-based materials and Fe-Si-based materials, and also in terms of color tone and appearance. There is no big difference. Therefore, P type and N
In order to distinguish between the thermoelectric materials, electrical properties must be measured or precise compositional analysis must be carried out unless a large amount of additive is added. In addition, even when a large amount of additive substance is added, the thickness of the layer formed by the surface treatment such as plating performed at the time of processing is wide, so that it is widely used like fluorescent X-ray analysis, and it is nondestructive and relatively easy to use the element. It was difficult to apply the analysis method that can perform the analysis.

Therefore, in the production of the thermoelectric element, if the P-type thermoelectric material and the N-type thermoelectric material are mixed with each other, a great problem occurs in the production of the element. In particular, after cutting the thermoelectric material into chips, there are many occasions when the P-type thermoelectric material chips and the N-type thermoelectric material chips are mixed in joining and assembling with the substrate, and when they are mixed, they are separated. There are few people. In addition, when there is a defective chip at the time of joining or assembling and the chip is to be replaced, it is difficult to determine whether the chip to be replaced is the P type or the N type.

[0007]

Therefore, in the present invention, in order to bond the thermoelectric material and the electrode formed on the substrate, the thermoelectric material processed into a plate shape having a necessary thickness (hereinafter, referred to as a plate-shaped material). The thermoelectric material is referred to as a thermoelectric material wafer.) P-type thermoelectric material and N-type thermoelectric material are different from each other in the substance forming the layer formed by the surface treatment such as wet plating, vapor phase plating or printing on both sides or one side. By using the substance, it is possible to easily distinguish the P-type and N-type thermoelectric materials in the steps after this step, and improve the manufacturability of the thermoelectric element (hereinafter, the thermoelectric module is also referred to as the thermoelectric element).

As the discrimination method, the discrimination based on the difference in color tone is the simplest and most practical, but in recent years, a method using an analyzer using fluorescent X-rays, which is relatively inexpensive and has become very popular, can be considered. As a method of using the difference in color tone, the color tone of a layer such as the outermost plating layer is changed between the P-type thermoelectric material and the N-type thermoelectric material. For example, when a metal layer is formed by wet plating or dry plating, a layer of a colored metal such as copper or gold or an alloy thereof is formed on the outermost surface of one type of thermoelectric semiconductor material to obtain a P type. It is possible to distinguish N type. When the conductive layer is formed by a printing method or the like, a colored conductive ink, for example, all or part of the contained metal particles is a colored metal such as copper or gold,
It is also effective to contain such things as pigments and dyes.
In the case of utilizing elemental analysis such as fluorescent X-ray analysis, it is possible to easily discriminate by including substances different in P-type and N-type in a layer formed by surface treatment at a level higher than the sensitivity of the analyzer.

[0009]

[Function] In order to bond the thermoelectric material and the electrode formed on the substrate, the substance constituting the layer formed by the surface treatment such as wet plating, vapor phase plating or printing is formed on both sides or one side of the thermoelectric material wafer. By using different substances for the N-type thermoelectric material and the N-type thermoelectric material, P
The mold and the N-type thermoelectric material can be easily discriminated, and the productivity of the thermoelectric element can be improved.

That is, in the layer formation by the surface treatment of the P-type and N-type thermoelectric materials of the present invention, the uppermost layer is made of a substance having a different color tone, or the color tone is changed in the substance constituting the uppermost layer. By adding such a substance, not only can the thermoelectric material wafer be discriminated, but also the thermoelectric material wafer can be discriminated easily even during assembly as a thermoelectric element. Further, among the substances forming the layer formed by the surface treatment, at least one kind of element is made different between the P-type and N-type thermoelectric materials, so that a relatively easy nondestructive analysis such as fluorescent X-ray analysis. According to the method, it is possible to distinguish between P type and N type.

[0011]

EXAMPLES An example in which a thermoelectric element of the present invention is manufactured using a sintered body of a Bi—Te based material which is most widely used as a thermoelectric material will be described below with reference to the drawings. As an example, by wet plating on a thermoelectric material wafer, to form a plating layer for joining to the electrode on the substrate by solder,
In the method for producing a thermoelectric element, an example will be described in which the uppermost layer of the P-type thermoelectric material and the N-type thermoelectric material is a plating layer having a different color tone.

FIG. 1 is a diagram outlining a manufacturing process for manufacturing the thermoelectric element of the present invention. First, a wafer-shaped P-type thermoelectric material 1 and a wafer-shaped N-type thermoelectric material 2 obtained by cutting the thermoelectric material to a size that should be the thickness of the thermoelectric material portion that constitutes the thermoelectric element are coated with nickel plating layers 3 on both surfaces thereof by wet plating. 10 μm is formed.

Next, a 1 μm copper plating layer 4 is formed only on the P-type thermoelectric semiconductor material 1 on which the nickel plating layer 3 is formed by a wet plating method. As a result, the surface of the P-type thermoelectric material becomes copper-colored, and the surface of the N-type thermoelectric material becomes metallic-colored by nickel plating, so that they can be clearly distinguished visually.

Next, the wafer-shaped P-type thermoelectric material 1 and N-type thermoelectric material 2 are cut into chips 5 and 6 each having the size of one element. In this case, the chips 5 and 6 have a rectangular parallelepiped shape, and a plating layer is formed on a pair of two surfaces facing each other. That is, in the P type, these outermost surfaces are covered with the copper plating layer 4, and in the N type, the nickel plating layer 3 appears. Therefore, even in this step, the distinction between the P type and the N type can be easily visually recognized. By the way,
Regarding the size of this chip, one side of the surface on which the plating layer is formed has a length of 1 mm, and the other sides have a length (thickness) of 0.8 mm.

Next, a copper plate having a thickness of 0.1 mm is laminated in advance on the insulating substrate 7 made of alumina so as to form a wiring pattern, and an electrode 8 formed by printing paste solder on the copper plate. By arranging the chips 5 and 6 with a jig and heating them, the substrate electrode 8 and the chips 5 and 6 are joined, and this joining is carried out for different substrates with P-type thermoelectric material and N-type thermoelectric material. To do. Even at this time, the opposite side of the joint had the color tone of each plating layer, and the distinction was easy. Finally, the substrates on which the P-type and N-type thermoelectric material chips are mounted are faced to each other, and the tip of the chips and the wiring of the other substrate are aligned and heated to melt the solder and perform P-type And N-type bonding were completed, and then lead wires were attached to the input / output electrodes to complete the thermoelectric element.

Through the manufacturing process of this thermoelectric element, the P-type thermoelectric material and the N-type thermoelectric material can be easily distinguished from each other until the final joining and assembly after plating, except for the wafer-shaped thermoelectric material in the state before plating. I was able to.

[0017]

According to the present invention, since the P-type thermoelectric material and the N-type thermoelectric material can be easily distinguished and discriminated during the production of the thermoelectric element, the productivity can be improved and at the same time during the production. Since defective thermoelectric material chips can be easily replaced in (1), a great effect is achieved in terms of product yield and cost.

Although the color tone of copper was used in the examples, this is because of consideration of easiness and cost in the manufacturing process and is not necessarily copper. Further, in the embodiment, the copper plating is performed after the nickel plating is performed, but the copper plating may be directly performed without performing the nickel plating. Alternatively, a conductive substance whose color tone changes by changing the film thickness can be used. Further, in the above-mentioned embodiment, the visual method, which is the easiest to discriminate, has been introduced. It can be easily identified by changing the element in the substance used for the surface treatment with the mold.

[Brief description of drawings]

FIG. 1 is a diagram showing an outline of a manufacturing process of a thermoelectric element used in an example for manufacturing a thermoelectric element of the present invention.

[Explanation of symbols]

 1 P-type thermoelectric material 2 N-type thermoelectric material 3 Nickel plating layer 4 Copper plating layer 5 P-type thermoelectric material chip 6 N-type thermoelectric material chip 7 Insulating substrate 8 Electrode

Claims (3)

[Claims] 1. A thermoelectric element comprising a P-type thermoelectric material, an N-type thermoelectric material, an electrode made of a conductive substance such as a metal for joining these thermoelectric materials, and a substrate for holding and fixing them. To bond these substances between the N-type thermoelectric material and the substrate, and the substance forming the layer (collectively referred to as “A layer”) provided for bonding these between the N-type thermoelectric material and the substrate Which is a substance constituting a layer (collectively referred to as an a layer) provided in a layer, and a substance constituting at least one of the a layer and the a layer is different from the substance constituting the other layer. A thermoelectric element containing a substance. 2. Of the layers provided for joining the thermoelectric material and the substrate, the substance constituting the layer formed on the surface of the thermoelectric material by surface treatment such as wet plating, vapor phase plating, printing is P-type. A thermoelectric element, wherein at least one kind of the thermoelectric material and the N-type thermoelectric material contain different substances. 3. Among layers provided for joining a thermoelectric material and a substrate, in a layer formed on the surface of the thermoelectric material by surface treatment such as wet plating, vapor phase plating or printing,
The substance forming the layer formed on the outermost surface of the P-type thermoelectric material and N
A thermoelectric material, characterized in that substances forming a layer formed on the outermost surface of the mold thermoelectric material have different color tones.