JPH01262678A - Laminated thermoelectric element and manufacture thereof - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION (a) Field of Industrial Application This invention relates to a laminated thermoelectric element formed by alternately laminating a plurality of p-type semiconductor ceramic plates and n-type semiconductor ceramic plates, and a method for manufacturing the same.

BACKGROUND ART Conventionally, in order to increase the thermoelectromotive force of a thermoelectric element, a plurality of p-type semiconductor layers and n-type semiconductor layers have been laminated to form a multilayer structure. For example, the thermoelectric element disclosed in JP-A No. 61-263176 has a plurality of p-type semiconductor layers and n-type semiconductor layers stacked alternately, leaving a pn junction at the interface of both layers to form a void layer. A laminated thermoelectric element is constructed by filling the void layer with a glass layer to form an insulating layer.

(C) Problem to be solved by the invention By the way, if the figure of merit of a thermoelectric element is generally 2, then Z
is expressed by the following equation.

Z=αt/l(ρ where α is the Seebeck coefficient, K is the thermal conductivity, and ρ is the specific resistance.

In the conventional example described above, a glassy layer is formed between multiple semiconductor layers and over the entire element surface, so it has excellent mechanical strength and reliability and is advantageous for power applications, but it is not suitable for sensor applications. In this case, the presence of glass in the detection part is not necessarily an advantage. That is, the thermal conductivity of the glass itself is generally high, the thermal conductivity K of the entire thermoelectric element increases, and the figure of merit Z decreases. For this reason, when a thermoelectric element is used as a thermal sensor, sensitivity decreases. Furthermore, the presence of glass increases the heat capacity of the entire detection section, reducing the response speed. Furthermore, when detecting infrared rays, the infrared rays are absorbed depending on the type and shape of the glass.

There is a problem that stable measurements cannot be made due to reflection or scattering.

An object of the present invention is to provide a laminated thermoelectric element that has excellent responsiveness by decreasing the thermal conductivity of the entire thermoelectric element to increase the figure of merit and reducing the heat capacity of the detection part, and a method for manufacturing the same. be.

(d) Means for Solving the Problems The laminated thermoelectric element of the present invention is a laminated thermoelectric element formed by alternately laminating a plurality of p-type semiconductor ceramic layers and n-type semiconductor ceramic layers. , is characterized in that a glass layer is formed only in areas excluding electrical connections.

Further, the method for manufacturing a laminated thermoelectric element of the present invention includes
A conductive paste is applied to the electrical connection portion of each of the type semiconductor ceramic plate and the n-type semiconductor ceramic plate to the adjacent semiconductor ceramic plate, and the p-type semiconductor ceramic plate and
By alternately laminating n-type semiconductor ceramic plates and integrating them by baking the conductive paste, glass powder is placed on the side surface of this integrated laminate and heated.
It is characterized by melting and impregnating glass into the void layer between each ceramic plate.

(e) Function In the laminated thermoelectric element of the present invention, a glass layer is formed between the p-type semiconductor ceramic layer and the n-type semiconductor ceramic layer only in the region excluding the electrical connection portion. Therefore, this glass layer bonds and integrates the respective semiconductor ceramic layers and acts as an insulating layer. Furthermore, since the glass layer is formed only between each semiconductor ceramic layer, an increase in thermal conductivity and heat capacity of the entire laminated thermoelectric element is suppressed. Therefore, it can be used as a highly sensitive and highly responsive thermal sensor.

In the method for manufacturing a laminated thermoelectric element of the present invention, a conductive paste is applied to the electrical connection portion of each of a plurality of p-type semiconductor ceramic plates and an n-type semiconductor ceramic plate with an adjacent semiconductor ceramic plate, and each semiconductor ceramic plate is coated with a conductive paste. The plates are stacked alternately and the conductive paste is baked on. As a result, a laminate is formed in which the semiconductor ceramic plates are electrically connected by the baked conductive paste! Thereafter, glass powder is placed on the side surface of this laminate and heated, whereby the glass powder melts and impregnates the gap between the ceramic plates. In this way, a glass layer is formed only in the gap layer formed between each semiconductor ceramic plate.

Note that p-type semiconductor ceramics include NiO, Feo, and C.
oo, a material consisting of one or more types of MnO
, O-doped materials, n-type semiconductor ceramics include B
aTiO3 or BaTiO3 with S rT ios
, CaTio:+, PbTio5
Rare earth or NbzO is added to the material in which one or more types of
@ + Material doped with one or more types of Tag Os,
Or T+O2 doped with NbzOs or Tazos, or ZnO with Al2O3 or Ga,
A material doped with 03 can be used.

In addition, as electrode materials, Pt, Pd, Ag-Pd, AA,
One or more types of Ni can be used.

(f) Example p-type semiconductor ceramic: Ni099.5mo1%
LizO is 0.5 moj against! % doped material was formed into a 50×20×O, 25 mm green sheet and fired in air at 1250° C. for 1 hour to obtain a sintered plate.

On the other hand, as an n-type semiconductor ceramic, BaBaTiO38
Q 41%, CaTi0 = 19.5 mo1%, Y, 03 doped material 0.5 mo1% 50X2
It was molded into a green sheet of 0.times.0.25 mm and fired in air at 1300.degree. C. for 1 hour to obtain a sintered plate.

Next, both sintered plates were cut into 1oxs with a diamond cutter.
xo, 2 mm (thickness is the dimension after shrinkage due to firing).

A conductive paste for forming electrodes was printed on the semiconductor ceramic plate thus formed. FIG. 2 shows one example, in which 1 indicates a p-type semiconductor ceramic plate and 3 indicates a conductive paste. Here, the conductive paste used was a paste obtained by kneading Ag, varnish, and frit solvent.

FIG. 1 is a perspective view showing a state before lamination of semiconductor ceramic plates printed with conductive paste. In the figure la, l
b, lc, ld are p-type semiconductor ceramic plates, 2a,
2b and 2c are n-type semiconductor ceramic plates. Further, 3a to 3g are conductive pastes. In addition, a conductive base) 3h (
(not shown) is printed. The semiconductor ceramic plates printed with each paste in this way were laminated, and after drying, the conductive paste was baked by heating to 950''C.

FIG. 3 shows the cross-sectional structure of the laminate integrated as described above. 3a to 3h become Ag electrodes by baking, and electrically connect one end of the p-type semiconductor ceramic plate and the n-type semiconductor ceramic plate.

Thereafter, as shown in FIG. 4(A), glass powder 4' was placed on the side surface of the laminate and melted at about 600°C. The molten glass naturally impregnates the void layer between each semiconductor ceramic plate due to gravity and capillary action. Note that it is desirable that the heat applied when melting the glass powder be set to a temperature lower than the electrode baking temperature.

After the insulating layer was formed between the semiconductor ceramic plates as described above, the unnecessary portion of the glass body 4 protruding from the side surface of the laminate was removed by polishing, as shown in FIG. 4(B).

FIG. 5 shows the cross-sectional structure of the laminated thermoelectric element manufactured as described above. In this way, a laminated thermoelectric element is obtained in which the glass layer 4 is formed only in the gap layer between each semiconductor ceramic plate.

In FIGS. 1, 3, and 5, the number of upper layers is shown as a small number, but the p-type semiconductor layer and the n-type semiconductor layer are each 1ON, and the dimensions after shrinkage due to electrode baking are 9×4.
5X4 (Lamination method) Form a laminate of 9mm
When a thermoelectric element was prepared by slicing it into a size of 4 (stacking direction) x 2 (slice width) mm, a thermoelectromotive force of about 20 m/cm was obtained.

(g1 Effect of the invention As described above, according to this invention, a glass layer is formed between each semiconductor ceramic layer only in the area excluding the electrical connection part, so the thermal conductivity of the entire element decreases and The overall heat capacity is reduced. Therefore, it is possible to construct a laminated thermoelectric element that can be used as a thermal sensor with high sensitivity and fast response speed.

[Brief explanation of the drawing]

FIG. 1 is a perspective view showing a state in the process of manufacturing a laminated thermoelectric element according to an embodiment of the present invention, and FIG. 2 is a diagram showing a semiconductor ceramic plate and a conductive paste printed thereon. FIG. 3 is a sectional view showing the structure of the laminated thermoelectric element during manufacture. FIGS. 4A and 4B are front views showing the laminated thermoelectric element in a state in the middle of manufacture, and FIG. 5 is a sectional view showing the structure of the completed laminated thermoelectric element. la~1d-p type semiconductor ceramic plate, 2a~2cmn
type semiconductor ceramic plate, 33-3h-conductive paste and electrode after baking, 4-glass and glass layer, 4'-glass powder. Applicant Murata Manufacturing Co., Ltd.

Claims (2)

[Claims] (1) In a laminated thermoelectric element formed by alternately laminating a plurality of p-type semiconductor ceramic layers and n-type semiconductor ceramic layers, a glass layer is formed only in the area between adjacent semiconductor ceramic layers except for the electrical connection part. A multilayer thermoelectric element characterized by: (2) A conductive paste is applied to the electrical connection portions of each of the plurality of p-type semiconductor ceramic plates and the n-type semiconductor ceramic plate to the adjacent semiconductor ceramic plate, and the p-type semiconductor ceramic plate and the n-type semiconductor ceramic plate are connected to each other. After the conductive paste is baked and integrated, glass powder is placed on the side of the integrated laminate and heated to melt and impregnate the void layer between each ceramic plate with glass. A method for manufacturing a laminated thermoelectric element, characterized by: