JPS6012703A - 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] Industrial Application Field The present invention is 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 and heating of equipment. It is related to.

Lecture on conventional examples and their problems Elements made of BaTiOs 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 is widely used because it does not require an external control circuit.

Conventional positive temperature coefficient thermistor heating elements have been obtained by press-molding BaTiO3-based semiconductor powder and then firing it, but it has been reported that it is difficult to obtain a practical thick film positive temperature coefficient thermistor heating element. Ta.

Conventionally, the following methods are known for processing BaTiOs-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) A conductive additive and glass frit are added to the kTi05 semiconductor powder to form a paste, which is screen printed on a substrate and then fired.

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

In addition, 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 troublesome and difficult to control. FiBaT depending on the material
This degrades the switching characteristics and self-heating characteristics of the iOs-based semiconductor. And by adding glass frit! l) Due to the difference in heat resistance and coefficient of thermal expansion between BaTiOs semiconductor and glass frit, it is susceptible to thermal shock and 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 manufacturing complexity that was a drawback of the prior art, and creates a film with excellent thermal shock resistance and thermal conductivity by forming a thick film without using glass frit. It is an object of the present invention to provide a method for easily manufacturing a thick film type positive characteristic semiconductor element 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
LaSi, LaSi2. La
A paste-like mixture made by adding one or more types of 58i5 powder in an amount of 1 to 6% by weight based on the total weight is applied onto a substrate to form a thick film, and then fired to form a thick film type. The purpose is to obtain a characteristic semiconductor element.

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, according to the present invention, La8i serves as both a conductive additive and a glass frit.

It is characterized by the use of LaSi2 or La5Sis. This LaSi, La5iz, La5
8i-s is a conductor at room temperature and is 1.10oO~1100"C
When the temperature exceeds this temperature, a part of the particles decomposes and forms SiO on the particle surface.
2 precipitates, but the inside of the particle remains intact and 5i02 on the surface
The membrane prevents decomposition. Therefore, BaTiOs-based semiconductor powder and LaSi.

When LaSi2 or La5Sis powder is mixed and fired, SiO2 precipitated on the surface of LaSi, LaSi2 or La5Sis plays the same role as glass frit,
Since the inside of the particle acts as a conductive additive, LaSi
, a thick film type positive temperature semiconductor device that does not require a glass frit can be obtained by simply adding LaSi 2 or La5Sis powder.

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 also improves.

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

Example 1 Addition of 1.0 mol% SrOt to BaTiOs 1300
After firing at °C, it is pulverized to obtain BaTiOs-based semiconductor powder. 20% by weight of LaSi powder based on the total weight is added to the BaTiOs semiconductor powder and mixed uniformly, and α-terpineol is further added to prepare a paste mixture 1.

On the other hand, a pair of electrodes 3゜4 made of a conductive substance such as mug is provided in advance on a substrate 2 made of Al2O5, etc., and a part of the electrodes 3゜4 remains on the electrodes 3, 4. The paste-like mixture 1'f is applied by double screen printing, heated from room temperature to 1360''G at a heating rate of 10''C/win, maintained for a period of time, and then allowed to cool in a furnace. In this way, a thick film type positive characteristic semiconductor device was obtained.

Example 2 3.0 mol% S was added to BaTiOs in the same manner as in Example 1.
After adding rO and firing at 1250'C, it is crushed to form BaT.
Obtain i05-based semiconductor powder. 36% by weight of La58i5 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. from 1
The temperature is raised to 1300''C at a heating rate of 0''C/min, held for 30 minutes, and then allowed to cool in the furnace. In this way, a thick film semiconductor element was obtained.

The area resistance at room temperature of the thick-film semiconductor device thus obtained was 0.80 in Example 1, but Ω/6n2, and in Example 2.
In this case, it was 0.25 KΩ/crn2, and the relationship between each temperature and resistance value was as shown in FIG.

In FIG. 2, "B" indicates the characteristics of the device obtained in Example 1, and "B" indicates the characteristics of Example 2.

Here, even when LaSi2 powder is used in place of the LaSi and La5Si5 powders, the same characteristics as in the above example can be obtained. Also, this LaSi,
It was confirmed that the same characteristics could be obtained even when two or more types of LaSi2°Lassi5 powder were mixed and added. And these are LaSi, LaSi 2 and 1
13 One or more types of La5Sis powder f
When it was added to BaTiO3-based semiconductor powder in an amount of 1 to 6% by weight based on the total weight, a thick film type positive characteristic semiconductor element having good characteristics was obtained.

Effect of the invention As described above, according to the manufacturing method of the present invention, LaSi.

LaSi 2 and Lasi 5 powders act as both traditional conductive additives and glass frits to provide electrical connections.

This has a sufficient effect on physical connection, and a thick film positive characteristic semiconductor element can be obtained without a glass frit.

Instead of glass frit, which has poor thermal conductivity, LaSi and LaSi2, which are conductive metals with good thermal conductivity, are used.
゜La5Si5f: By using it, heat conduction is improved and thermal shock resistance is improved.Furthermore, since it is manufactured by screen printing etc., the work is easy and mass production is possible.

In the present invention, the BaTiO3-based semiconductor powder may be any BaTiO5 powder made by adding various additives to convert it into a semiconductor, as long as it is δ-filtered. Also, LaSi.

LaSi2. When the amount of La5S15 powder added is outside the range of 1 to 6% by weight based on the total weight, if it is less than 1% by weight, the area resistance becomes too large and is not suitable for a heating element.
It is also impossible to physically fix BaTiOs powders together; on the other hand, 6
This is because if it exceeds 0% by weight, the sheet resistance becomes too small and the self-control characteristic (PTC characteristic) decreases, making it unsuitable for a heating element. Furthermore, BaTi0s-based semiconductor powder and LaSi, LaSi2, LasSis
An organic solvent (in the example, α~
Terpineol) was used, but any material that can be made into a paste may be used.

As described above, according to the present invention, a thick film type positive characteristic semiconductor device that does not require a glass frit can be manufactured by thermal spraying.
Its practical effects are significant.

[Brief explanation of the drawing]

FIG. 1 is a partially cutaway perspective view showing a thick film type positive characteristic 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. Name of agent: Patent attorney Toshio Nakao (1st person)
Figure 2 → Bottle performance (1C)

Claims (1)

[Claims] LaSi, LaSi2, L in BaTiO3-based semiconductor powder
It is characterized by adding one or more types of a5Si3 powder in an 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 for 1,000 years. A method for manufacturing a thick film type positive characteristic semiconductor device.