JPS60261105A - Method of producing thick film positive temperature coefficient semiconductor element - 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 Field of Industrial Application The present invention relates to a method for manufacturing a thick-film positive temperature coefficient semiconductor element that does not require a glass frit, which is a sheet heating element used for heat insulation of equipment, knife heating, etc. It is something.

Conventional configuration and problems Elements made of BaTiO3-based semiconductors have switching characteristics in which the resistance value increases rapidly above a certain temperature and self-heating characteristics after switching, and have fast temperature rise characteristics and self-temperature control functions. However, it is widely used because it does not require an external control circuit.

The conventional positive temperature coefficient thermistor heating element is B a T i O5
It was obtained by press-molding a semiconductor powder and then firing it.
It has been considered difficult to obtain a practical thick-film positive temperature coefficient thermistor heating element.

Conventionally, the following methods are known for processing BaTiO3-based semiconductors into a film.

■ After forming into a disk shape, the fired product is polished into thin pieces.

■ Form a thin film on the substrate by vacuum evaporation.

(2) Conductive additives and glass frit are added to BaTiO3-based semiconductor powder to form a paste, which is screen printed on a substrate and then fired.

However, in the method (2) above, since the crystal grain size of the BaTiO3 semiconductor is large and brittle, it is extremely difficult to polish it into a film. Furthermore, in the method (2), the operation is troublesome and it is difficult to obtain a large amount of electric power suitable for one heating element. Furthermore, method (1) has a high sheet resistance and is difficult to control, is not suitable for heating elements, and requires preparing and firing the glass frit in advance, which is troublesome and difficult to control. BaT depending on the material
It deteriorates the switching characteristics and self-heating characteristics of iO3-based semiconductors. Adding glass frit makes it vulnerable to thermal shock due to the difference in heat resistance and coefficient of thermal expansion between the BaTiO3 semiconductor and the glass frit, which impedes heat conduction. Furthermore, it is difficult to uniformly mix conductive additives and glass frit, which is one of the causes of variations in properties.

Purpose of the Invention Therefore, the present invention solves the drawback of the prior art, which is the complexity of manufacturing, and creates a film with excellent thermal shock resistance, thermal conductivity, and uniformity by forming a thick film without using glass frit. The purpose and goal of this invention is to provide a method for easily manufacturing thick film type positive temperature semiconductor devices with such characteristics.

Structure of the Invention The method for manufacturing a thick film type positive temperature semiconductor device of the present invention includes
t(j, 1.0 to 60.○ of Ca B6 to the based semiconductor powder
The purpose is to obtain a thick film type positive characteristic semiconductor element by coating a paste-like mixture on a substrate to form a thick film and then firing it.

In the conventional method of using a conductive additive and glass frit, a conductive additive is required for electrical connection between BaTiO3-based semiconductor powders, and a glass frit is required to physically connect BaTiO3-based powders together. Met.

However, the present invention is characterized in that Oa B6 is used as a material that functions as both a conductive additive and a glass frit. This CaB6 is not a conductor at room temperature, but at temperatures above 1000-1100℃, a portion decomposes and B2O5 is precipitated on the particle surface.
The inside of the particle remains intact and decomposition is prevented by the B2O3 film on the surface. Therefore, when B a Ti O5 based semiconductor powder and Ca B 6 powder are mixed and fired, Cj a
B2O3 precipitated on the surface of B6 plays the same role as a glass frit, and the inside of the particle plays the role of a conductive additive, so it is a thick film type positive temperature semiconductor that does not require a glass frit just by adding CaB6. An element is obtained.

Furthermore, by adding a conductive metal, the thermal conductivity becomes better than that of glass frit, which has poor thermal conductivity, and the thermal shock resistance is also improved.

DESCRIPTION OF EMBODIMENTS Below, embodiments of the present invention will be specifically explained with reference to FIG.

Example 1 1. Add Nb2O5 of ot=nil and 1
After firing at 300°C, it is pulverized to obtain BaTiO3-based semiconductor powder. A paste-like mixture 1 is prepared by uniformly mixing 5.0% by weight of CaB6 powder with respect to the total weight of the BaTiO3-based semiconductor powder and adding α-terpineol.

On the other hand, AQ20. A pair of electrodes 3.4 made of a conductive material such as Aq are provided in advance on a substrate 2 made of Aq, etc., and the paste-like mixture is placed so that a part of the electrodes 3.4 remains on the electrodes 3, 4. 1 by screen printing, etc., and heated at a heating rate of 10°C/min from room temperature to 13°C.
After raising the temperature to 60° C. and maintaining it for 1 hour, it was left to cool in the furnace.

In this way, a thick film type positive characteristic semiconductor device was obtained.

Example 2 In the same manner as in Example 1, 3.0 mol of Y was added to BaTiO3.
After adding 2O3 and firing at 1250℃, it is crushed to form BaT.
An iO3-based semiconductor powder is obtained. 24.0% by weight of CaB6 powder based on the total weight is added to the BaTiO3-based semiconductor powder and mixed uniformly, and α-terpineol is further added to form paste mixture 1. Next, as in Example 1, the electrodes 3 and 4 are provided on the substrate 2 in advance, and the paste mixture 1 is applied by screen printing or the like so that a portion of the electrodes 3 and 4 remains. 1 from room temperature
1300'C' at a heating rate of 0°C/min! After raising the temperature at , and holding it for 30 minutes, it was left to cool in the furnace. In this way, a thick film semiconductor device was obtained.

The sheet resistance at room temperature of the thick film semiconductor device thus obtained was 6.1 Ω/Ca in Example 1, and 2.8 Ω/Ca in Example 2, and the resistance depended on each temperature. The relationship between the values was as shown in FIG. In FIG. 2, A shows the characteristics of the device obtained in Example 1, and B shows the characteristics in Example 2.

Effects of the Invention As described above, according to the manufacturing method of the present invention, CaB6 powder plays the role of both a conventional conductive additive and a glass frit, and has sufficient effects for electrical connection and physical connection. ,
A thick film positive characteristic semiconductor element can be obtained without a glass frit.

However, by using CaB6, a conductive metal with good heat conduction, instead of glass frit, which has poor heat conduction, not only good heat conduction but also improved thermal shock resistance can be achieved. moreover,
Since it can be manufactured by screen printing, etc., it is easy to work with and mass production is possible.

In the present invention, any BaTiO3-based semiconductor powder may be used as long as it is made into a semiconductor by adding various additives to BaTiO3. In addition, the amount of Ca B6 powder added was defined as 1 to 60% by weight based on the total weight.
If it is less than 60% by weight, the area resistance becomes too large, making it unsuitable for use as a heating element, and it is impossible to physically fix the BaTiO3 powders together. This is because the characteristics) are unsuitable for small Kunaku heating elements. Further, although an organic solvent (α-terpineol in the example) was used to make the 13aTi03-based semiconductor powder and Ca B6 powder into a paste, any solvent may be used as long as it can be made into a paste.

As described above, according to the present invention, it is possible to easily manufacture a thick film type positive characteristic semiconductor element that does not require glass frino I, and its practical effects are great.

[Brief explanation of drawings]

FIG. 1 is a partially cutaway perspective view showing a thick film positive temperature coefficient semiconductor device obtained by the method of the present invention, and FIG. 2 is a diagram showing the relationship between temperature and resistance value of the device according to an embodiment of the present invention. 1... Paste mixture, 2 - Substrate, 3, 4...
··electrode.

Claims (1)

[Claims] Adding CaB6 to BaTiO3-based semiconductor powder from 1.0 to 6
1. A method for manufacturing a thick-film type positive characteristic semiconductor element, comprising: applying 0.0% by weight of a paste-like mixture onto a substrate to form a thick film, and then firing the mixture.