JPH02228082A - Manufacture of thermoelectric generating element - Google Patents

Abstract

PURPOSE:To contrive the simplification of manufacture processes and the reduction of costs by welding metallic terminals to the both ends of a member for p-type and a member for n-type which have the metal properties remaining after sintering by resistance welding, after which the heat treatment for turning said p-type and n-type members into semiconductors and dissolving the stress distortion of the welded part is carried out. CONSTITUTION:The p-n junction of a member for p-type 1 and a member for n-type 2 which have the metal properties remaining after sintering is resistance-welded indirectly through a metal plate 4 (a), or directly without interposing the metal plate 4 (b), whereas a metallic terminals 3 is welded to the both sides of the above members by resistance welding. Next, the heat treatment is carried out under such conditions that said p-type an n-type members 1 and 2 are turned into semiconductors and the stress distortion of the p-n junction W1 and metal terminal welded parts W1 and W2 is dissolved. Accordingly, a complex brazing process and a special brazing material become unnecessary and also the stress distortion of the welded part can be removed under the heat treatment conditions for turn into semiconductors. As a result, thermoelectric generating elements which have excellent strength of terminal junction can be manufactured easily and the reduction of costs becomes possible.

Description

DETAILED DESCRIPTION OF THE INVENTION (Industrial Field of Application) The present invention relates to a method for manufacturing a thermoelectric power generation element made of an iron silicide semiconductor.

(Prior art and its problems) Various silicide semiconductor devices have been proposed as thermoelectric power generation devices, but iron silicide devices can be made into p-type or n-type by adding appropriate impurities. In addition, since the raw materials iron and silicon are abundant and inexpensive, they have the advantage of being able to produce economical thermoelectric power generation elements, and have attracted attention in recent years.

However, in order to put such a thermoelectric element into practical use, it is necessary to attach an electrode terminal for conducting electricity to the end of the element, but resistance welding of the electrode terminal to the semiconductor part actually requires contact resistance (semiconductor side The specific resistance (about 10 −3 Ωcm) is too large, making it difficult. Therefore, at present, bonding is performed using a silver paste method, a brazing method, an ultrasonic soldering method, etc. (see, for example, Japanese Patent Laid-Open No. 57-95684).

(Problem to be Solved by the Invention) However, in the case of brazing, the brazing material may diffuse into the thermoelectric element after joining, which may cause cranking, resulting in a lack of reliability in the connection. There is. In addition, when brazing is used for industrial purposes (mass production), it involves a process in which brazing material is applied to the connection parts and lead terminals of the thermoelectric generator in advance, a process in which the thermoelectric generator and the lead terminals are overlapped, and a process is performed at a predetermined temperature. A process of melting the brazing filler metal by passing it through a heating furnace set to 100 mL is required, which increases the number of man-hours and requires the use of a special brazing filler metal, resulting in problems that lead to higher costs. Furthermore, the silver paste method and the ultrasonic soldering method have a problem in that the bonded portion lacks heat resistance.

In addition, if p-type and n-type elements are manufactured separately, the pixel elements cannot be joined by resistance welding, which currently requires p-n junctions using metal plates, but in high-temperature thermoelectric power generation elements, p-n Since the temperature at the joint is as high as 1150K, metal plates for p-n junctions and brazing depend on the heat resistance and oxidation resistance of the material.
The characteristics of Fe5iz cannot be exhibited. Therefore, although it is necessary to manufacture it integrally, there are problems in that not only the shape is limited due to the manufacturing process, but also mass productivity is lacking.

Therefore, the present invention provides a method that can replace conventional brazing, etc., achieve high reliability of joints, simplify the manufacturing process, and manufacture low-cost thermoelectric power generation elements. That is the issue.

(Means for Solving the Problems) The present invention provides that the orthosilicate material has a semiconductor-metal transition that becomes a metallic phase at 1259 or above, and that it is usually sintered at a temperature above the above transition temperature after pressing the raw material powder. Then, since it is made into a semiconductor by heat treatment below the transition temperature, the as-sintered element material has metallic properties and can be resistance welded. This was done with a focus on being appropriate for resolving the issue.
Resistance welding a gold gI4 terminal and/or a p-n bonding member to the ends of the as-sintered p-type member and/or n-type member using its metallic properties, and then welding the above-mentioned p-type member and The first invention is characterized in that the stress strain at the joint between the electrodeposited metal terminal and the pixel element is eliminated by using heat treatment for converting the n-type member into a semiconductor. When manufacturing a thermoelectric power generation element by p-n bonding a silicide material and an n-type iron silicide material, a resistor is added to both ends of the above-mentioned p-type member and n-type member, which have metallic properties as they are sintered. Manufacturing a thermoelectric power generation element, the gist of which is to weld metal terminals by welding, then convert the p-type and n-type members into semiconductors, and perform heat treatment under conditions to eliminate stress and strain at the welded metal terminals. It's in the law.

The above method is suitable for integrally manufacturing p-n junction pixel elements, but when manufacturing p-type elements and n-type elements separately, resistance welding is used for the p-n junction as well. It is necessary to join by

Therefore, the second invention is to manufacture a thermoelectric power generation element by p-n bonding a p-type iron silicide material and an n-type iron silicide material, and to produce the above-mentioned P-type material having metallic properties as sintered. The p-n junction of the N-type member and the N-type member is resistance welded indirectly through a metal plate or directly without a metal plate, and metal terminals are welded to both ends of the above member by resistance welding. and then converting the p-type and n-type members into semiconductors and performing heat treatment under conditions that eliminate stress strain at the p-n junction and the metal terminal weld. It's in the law.

Furthermore, as shown in FIG. 3, the method of the present invention can be used to
It can also be applied to the case where a thermoelectric power generating element is manufactured by resistance welding the metal element 5 to the type semiconductor element 1.2. In the above resistance welding, as shown in FIG.
It is also preferable to form one or more protrusions 6 at the joint portion of the metal element 5 with the semiconductor element, since current will be concentrated during resistance welding and welding and joining will be facilitated.

In the present invention, since both p-type and n-type devices are manufactured by resistance welding using the semiconductor-metal transition phenomenon of the device, A
It is preferable to manufacture a P-type element by a powder metallurgy method by adding I or Mn, and usually a composition of Pei-xMnxsix (0<x<0.1) in which a predetermined amount of Mn is added to Pe5iz is used.

On the other hand, the n-type element is made by adding CO to the above iron silicide and using a powder metallurgy method to form Fe1-ycoysil (0<, <0.1
) is preferably prepared.

The raw material powder is cold pressed and then sintered. As shown in FIG. 2(a), the thermoelectric generating element is formed by once manufacturing a rod-shaped p-type semiconductor element l and an n-type semiconductor element 2, and then joining them in a π-shape by resistance welding via a metal plate 4. At the same time, the metal terminals 3 are joined by resistance welding, or the p-type semiconductor element l is connected in a U-shape as shown in FIG.
and n-type semiconductor element 2 are integrally molded so as to form a p-n junction, and metal terminals 3 are joined by resistance welding.

Note that welded parts are indicated by -1 or total.

As the above-mentioned resistance welding, a normal electric resistance welding method may be employed.

(Function and Effect) According to the present invention, the point in time when the element material is in a metallic state during the manufacturing process of a thermoelectric generating element is captured, and welding is performed by utilizing the metallic properties of the element material. Welding becomes possible, and complicated brazing processes and special brazing metals are not required, making it possible to reduce costs. Furthermore, stress and strain can be simultaneously removed from such welded parts under heat treatment conditions for converting element materials into semiconductors, making it possible to easily manufacture thermoelectric generators with excellent terminal bonding strength without adding special processes. can. At the same time, resistance welding is also possible for p-n junctions, so p-type and n-type joints can be welded separately.
Even if a type element is manufactured, it can be used as a thermoelectric power generation element/device.

Hereinafter, the present invention will be explained in detail based on examples.

(Example) A thermoelectric power generation element is manufactured by the steps shown in FIG.

A predetermined amount of Mn is added to Pe5iH to produce Fe1-Jn, Six (O<+ <0.
1)! The raw materials Fe, Si, Mn are
The mixture is mixed and dissolved, pulverized to 32 meshes in a stamp mill, and then pulverized in an iron ball mill to a particle size in the range of 1 to 31 ml to be used as a powder for p-type elements. On the other hand, pe
Pe+-yCo, which has a semiconductor-metal transition transformation by adding a predetermined amount of Co to slg, 5ix (0<, <0.1)
Raw materials Fe, Si, and Co are mixed and dissolved so as to have the following composition, ground to 32 mesh particles using a stamp mill, and then ground to a particle size range of 1 to 3III11 using an iron ball mill to be used as a powder for n-type devices. .

Before performing the above cold pressing, the powder is granulated into aggregates by adding binders and lubricants such as polyvinyl alcohol and colloidal paraffin, and is pressed into powder with a filling rate of 60'-'65% using a hydraulic press. The binder and lubricant are completely removed before sintering by preheating in air at 600 to 800 °C. Sintering is performed in vacuum (1.33×10 Pa) at around 1428°C.

The as-sintered element had a specific resistance of about 10-'Ωc+s, which was extremely small compared to the specific resistance after heat treatment, so a metal terminal, such as stainless steel, was welded by ordinary resistance welding. Thereafter, heat treatment was performed before and after 1050 mL in air or an inert gas such as nitrogen gas to produce a thermoelectric power generation element. This heat treatment makes it possible to remove stress strain after resistance welding, and improves the reliability of the joint. Note that during the resistance welding, it is advisable to take measures such as heating to a certain extent in order to alleviate thermal shock.

When the performance and strength of the terminal joints were compared with those of thermoelectric generators manufactured by conventional brazing methods, it was confirmed that the reliability and heat resistance of the joints were improved.

[Brief explanation of the drawing]

FIG. 1 is a process diagram showing the manufacturing process of the thermoelectric power generation element according to the present invention, FIGS. 2(a) and (b) are front views showing the form of the thermoelectric power generation element manufactured by the method of the present invention, and FIG. 4 is a schematic side view showing the form of a thermoelectric power generating element in which a metal element is bonded to a p-type or n-type element, and FIG. 4 is an enlarged view showing the shape of a joint portion of a metal terminal bonded to the thermoelectric generating element. 1----・p-type element, 2-・-n-type element, 3-・-・
・−・Metal terminal, 4−−−−1 metal plate, 5−・・−
...-Metal element, -1 and -2--Welded part. Patent applicant: Yamato Vacuum Industry Co., Ltd.

Claims (4)

[Claims] (1) When manufacturing a thermoelectric power generation element by p-n bonding a p-type iron silicide material and an n-type iron silicide material, the above-mentioned p-type member and n-type member having metallic properties as sintered are used. Metal terminals are welded to both ends of the member by resistance welding, and then heat treatment is performed under conditions to convert the p-type and n-type members into semiconductors and to eliminate stress distortion in the welded parts of the metal terminals. A method for manufacturing thermoelectric power generation elements. (2) When manufacturing a thermoelectric power generation element by p-n bonding p-type iron silicide material and n-type iron silicide material, the above-mentioned p-type member and n-type member having metallic properties as sintered are used. While the p-n junction of the members is resistance welded indirectly through a metal plate or directly without a metal plate, metal terminals are connected to both ends of the above-mentioned p-type member and n-type member by resistance welding. A thermoelectric power generating element characterized in that the p-type and n-type members are welded, and then heat treatment is performed under conditions that convert the p-type and n-type members into semiconductors and eliminate stress strain in the p-n junction and the metal terminal welded portion. manufacturing method. (3) When manufacturing a thermoelectric power generation element by joining a metal terminal to a p-type iron silicide material or an n-type iron silicide material, the above-mentioned p-type member or n-type member has metallic properties as sintered. A metal terminal is welded to the end of the metal terminal by resistance welding, and then heat treatment is performed under conditions that convert the p-type member or n-type member into a semiconductor and eliminate stress strain at the welded part of the metal terminal. A method for manufacturing thermoelectric power generation elements. (4) The method for manufacturing a thermoelectric generating element according to any one of claims (1) to (4), wherein one or more protrusions are provided on the welded portion of the metal terminal.