JPS61101007A - Manufacture of thick film type 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] Industrial Application Field 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 moisturizing, heating, etc. of equipment. It is.

Conventional structure 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. It has 2 external control circuits.

It is widely used because it requires a lot of power.

Conventional positive temperature coefficient thermistor heating elements were obtained by press-molding BaTiO3-based semiconductor powder and then firing it, but it was considered difficult to obtain a practical thick film positive temperature coefficient thermistor heating element. .

Conventionally, the following methods are known for processing BaTi (15-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 BaTiOs semiconductor powder to form a paste, which is screen printed on a substrate and then fired.

However, in the method (2), since the BaTiO3-based semiconductor has a large crystal grain size and is brittle, it is extremely difficult to polish the BaTiO3-based semiconductor into a film. In addition, the method (2) is cumbersome to operate, and it is difficult to obtain a large amount of power suitable for the heating element.

Furthermore, method (2) above tends to have 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 both troublesome and difficult to control. Depending on the material of the glass frit, the switching characteristics and self-heating characteristics of the BaTiO3 thread conductor may deteriorate. By adding glass frit, Ba
Due to the difference in heat resistance and coefficient of thermal expansion between TiOs-based semiconductors and glass frit, they are susceptible to thermal shock and impede 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 manufacturing complexity that was a drawback of the prior art, and by forming a thick film without using glass frit, it has excellent thermal shock resistance and thermal conductivity, and has uniform properties. It is an object of the present invention to provide a method for easily manufacturing a thick film type positive characteristic semiconductor device having the following characteristics.

Structure of the Invention The method for manufacturing a thick film type positive temperature semiconductor device of the present invention includes
Ti2B is added to the iOx semiconductor powder in a mixed amount of 1 to 60% by weight based on the total weight, and the paste-like mixture is applied onto a substrate to form a thick film, and then fired to form a very thick film. The purpose is to obtain a type positive characteristic semiconductor device.

In the conventional method using conductive additives and glass frit, conductive additives are required to establish electrical connections between BaTiO3 semiconductor powders, and glass frits are required to connect BaTiO3 thread powders to all powders. Ta.

However, the present invention is characterized in that Ti2B is used as both a conductive additive and a glass frit. Ti2B is a conductor at room temperature, and at temperatures above 1000-1100°C, a portion of it decomposes and B2O5 precipitates on the particle surface, but the inside of the particle remains the same! ! : Decomposition is inhibited by the B2O3 film on the surface. Therefore, BaTi05-based semiconductor powder and Ti2
When B powder is mixed and fired, the B2O3 precipitated on the surface of Ti2B plays the same role as the glass frit, and the inside of the particles plays the role of a conductive additive, so just adding Ti2B requires a glass frit. A very thick film type positive characteristic semiconductor device can be obtained.

In addition, by adding a conductive metal, it has better thermal conductivity than glass frit, which has poor thermal conductivity11), and also improves thermal shock resistance.

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

Example 1 1-Q-[=/l/% of Nb2O5 is added to BaTi03 and fired at 1300°C, followed by pulverization to obtain BaTiO3-based semiconductor powder. A paste-like mixture 1 is prepared by adding 1.5% by weight of Ti2B powder based on the total weight to the BaTiO3-based semiconductor powder and mixing uniformly, and then adding α-terpineol.

On the other hand, a pair of electrodes 3.4 made of a conductive material such as Ag is provided in advance on a substrate 2 made of Al2O3, etc., and a part of the electrodes 3.4 is left on the electrodes 3, 4. The paste-like mixture 1 was applied by screen printing or the like, and heated from room temperature to 106 bases.

The temperature was raised to 1350°C at a rising rate of 'C/min, held for 1 hour, and then allowed 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, jO mol% of N was added to 13aTi03.
After adding d2O3 and firing at 1250°C, crush it to obtain B
Obtain aTiO3-based semiconductor powder. 30% by weight of Ti2B powder based on the total weight is added to the BaTiOs 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 remain. , room temperature to 1
Raise the temperature to 1300°C at a heating rate of 0'C/min, and
After holding for a minute, let it cool in the furnace. In this way, a thick film semiconductor element was obtained.

The sheet resistance at room temperature of the thick-film semiconductor device thus obtained was 5, OKQ/ (, J, and Ω/c2 in the case of Example 1, and 1.3 and Ω/c2 in the case of Example 2, respectively). The relationship between the resistance value 7 and the resistance value was as shown in FIG. 2. 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, Ti2B 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 using glass frits.

Furthermore, by using Ti2B, a conductive metal with good heat conduction, instead of glass frit, which has poor heat conduction, heat conduction is improved and thermal shock resistance is also improved. Furthermore, since it can be manufactured by screen printing or the like, the work is easy 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 addition amount of Ti2B powder was specified as 1 to 60% by weight based on the total weight, because if it was less than 1% by weight, the area resistance would become too large and it would be unsuitable for a heating element. On the other hand, if it exceeds 60% by weight, the sheet resistance becomes too small and the self-control characteristics (PTC characteristics) become small, making it unsuitable for use as a heating element. Furthermore, an organic solvent (
In the actual process, α-terpineo) V) was used, but any material that can be made into a paste form may be used.

As described above, according to the present invention, it is possible to easily manufacture a thick film type positive characteristic semiconductor device that does not require a glass frit.
Its practical effects are significant.

[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] A thick film characterized by adding Ti_2B to BaTiO_3-based semiconductor powder in a mixed amount of 1 to 60% by weight based on the total weight, applying the paste-like mixture on a substrate to form a thick film, and then firing it. A method for manufacturing a film type positive characteristic semiconductor device.