JPS6158202A - 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 glass frit, among planar heating elements used for heat insulation and heating of equipment, etc. It is.

Conventional configuration and its problems BaTi0. Elements made of semiconductors have switching characteristics in which the resistance value increases rapidly above a predetermined temperature and self-heating characteristics after switching.
It is widely used because the trtj control function is not limited to the entire functional external IU1 control circuit.

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 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.

(4) A tetraelectric additive 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) above, since the crystal grain size of the BaT-O3-based semiconductor is large and 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.

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 cumbersome and depends on the material of the glass frit. is BaTi
It deteriorates the switching characteristics and self-heating characteristics of Cl3-based semiconductors. Addition of 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 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
A thick film type positive characteristic semiconductor element is produced by adding 1 to 60% by weight of at least one of 5OB215cLz to iO3-based semiconductor powder to form a base, and applying the mixture onto a substrate to form a thick film and then firing it. That's what you're trying to get.

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. However, the present invention is characterized in that 5cB2 and/or SOB + 2 is used as a material that functions as both a conductive additive and a glass frit. This 5CB2 r "CB12 is a conductor at room temperature, but when the temperature reaches 1000~11oooC or higher, a portion of it decomposes and 8203 is precipitated on the particle surface, but the inside of the particle remains intact and the 8205 film on the surface prevents decomposition. Therefore, BaTi05-based semiconductor powder and 5CB2*S
When CB+2 powder is mixed and fired, 5CB2,5
Since B2O3 plays the same role as Kakarasufurinoto precipitated on the surface of CB12, and the inside of the particle plays the role of a conductive additive, a thick film type positive temperature semiconductor element that does not require a glass frit can be obtained by simply adding 5cB2 and 5cB12. It will be done.

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 B? L T 103 i'CI -0mo)Ii' %
After adding 20 s of nitrogen and firing at 1300'C,
It is pulverized to obtain BaTiO3-based semiconductor powder. Said BaT
i05-based semiconductor powder contains 5cB of 5% by weight based on the total weight
Powder 2 is added and mixed uniformly, and α-terpineol is further added to prepare paste mixture 1.

On the other hand, a pair of electrodes 3.4 made of a conductive material such as Ag is provided in advance on the substrate 2 made of A(120s), and one of the electrodes 3.4 is placed on the electrode 3.4. The paste-like mixture 1 is applied by screen printing or the like so that a portion remains, and the temperature is raised from room temperature to 1350°C at a temperature increase rate of 10°C/min, held for 1 hour, and then allowed to cool in a 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 molti of L was added to BaT 05.
After adding a2O3 and firing at 1250°C, crush it to obtain B
A Ti0 B-based semiconductor powder is obtained. 40% by weight of SCB+2 powder based on the total weight is added to the BaTi05 semiconductor powder and mixed uniformly, and α-terpineol is further added to form paste mixture 1. Next, as in Example 1, the electrodes 3.4 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 3.4 remains. The temperature was raised from 10°C to 1300°C at a heating rate of 10°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 of the thus obtained thick film semiconductor device at room temperature was 5.3 Ω/cm' in the case of Example 2, and 0.5 KΩ/cm' in the case of Example 2, and at each temperature. The relationship between the resistance value and the 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 in Example 2.

Effects of the Invention As described above, according to the manufacturing method of the present invention, 5CB2+S
OB j 2 powder plays the role of both a conventional conductive additive and a glass frit, has sufficient effects for electrical connection and physical connection, and thick-film positive temperature semiconductor devices can be obtained without a glass frit. That will happen.

In addition, instead of glass frit, which has poor thermal conductivity, 5CB2 is a conductive metal with good thermal conductivity. By using SOB+2, heat conduction is improved and thermal shock resistance is also improved. Furthermore, since it can be manufactured by screen printing or the like, it is easy to work 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 BaTiOs. Also, 5cB2゜5cB12
The reason why the amount of powder to be added is specified as 1 to 6% by weight based on the total weight is that if it is less than 1% by weight, the area resistance will be too strong and it will be unsuitable for a heating element. On the other hand, if it exceeds 60 times, the sheet resistance becomes too small and the self-control characteristic (PTC: characteristic) becomes small, making it unsuitable for a heating element. Furthermore, BaT
i05-based semiconductor powder and 5CB2. An organic solvent (α-terpineol in the example) was used to make the SCB+2 powder into a paste, but any solvent may be used as long as it can be made into a paste. Although the examples show only one type of additive, it was confirmed that the same effect could be obtained even if two types were added at the same time.

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 great.0

[Brief explanation of drawings]

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. ... Paste mixture, 2 ... Substrate, 3.4 ... Electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person No. 1
Figure 2 Figure 1 No. 1 [(・C]

Claims (1)

[Claims] S_cB_2, S_cB in BaTiO_3-based semiconductor powder
A thick-film type positive characteristic semiconductor device, characterized in that it is formed by adding 1 to 60% by weight of at least one of _1_2 and making a paste-like mixture onto a substrate to form a thick film, and then firing the mixture. Production method.