JPH0534807B2 - - Google Patents

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, among planar heating elements used for heat insulation and heating of equipment. be.

Conventional structure and its problems Elements made of BaTiO ₃ -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 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 BaTiO ₃ semiconductor powder and then firing it, but it is said to be difficult to obtain a practical thick film positive temperature coefficient thermistor heating element. Ta.

Conventionally, the following methods are known for processing BaTiO ₃ -based semiconductors into a film.

After being formed into a disk shape, it is fired and polished into thin pieces.

A thin film is formed on the substrate by vacuum evaporation.

Conductive additives and glass frit are added to BaTiO ₃ -based semiconductor powder to form a paste, which is then screen printed onto a substrate and then fired.

However, in the above method, it is extremely difficult to polish the BaTiO ₃ -based semiconductor into a film because the crystal grain size of the BaTiO 3 -based semiconductor is large and brittle. Furthermore, the above method is cumbersome to operate, and it is difficult to obtain a large amount of power suitable for the heating element. Furthermore, the above-mentioned method tends to increase 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 depends on the material of the glass frit. teeth
Deteriorates the switching characteristics and self-heating characteristics of BaTiO ₃ semiconductors. Adding glass frit makes it vulnerable to thermal shock due to the difference in heat resistance and coefficient of thermal expansion between BaTiO ₃ -based semiconductors and glass frit, which impedes heat conduction. Furthermore, it is difficult to uniformly mix the conductive additive and the glass frit, which is one of the causes of variations in properties.

Purpose of the Invention Therefore, the present invention solves the drawbacks of the above-mentioned conventional technology, which is the complexity of manufacturing, and achieves excellent thermal shock resistance, thermal conductivity, and uniform properties 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 characteristic semiconductor element of the present invention includes adding _{Ni 3} Si, Ni ₅ Si ₂ ,
A paste-like mixture containing 1.0 to 60.0% by weight of at least one of Ni ₃ Si ₂ , Ni ₂ Si, and NiSi is applied onto a substrate to form a thick film, and then baked to create a thick film type. The purpose is to obtain a positive characteristic semiconductor device.

In the conventional method of using conductive additives and glass frits, conductive additives are required to electrically connect BaTiO ₃ -based semiconductor powders to each other, and glass frits are required to physically connect BaTiO ₃ -based powders to each other. It was hot.

However, according to the present invention, as a material that functions as both a conductive additive and a glass frit,
It is characterized by the use of Ni ₃ Si, Ni ₅ Si ₂ , Ni ₃ Si ₂ , Ni ₂ Si or NiSi. These Ni ₃ Si,
Ni ₅ Si ₂ , Ni ₃ Si ₂ , Ni ₂ Si, and NiSi are conductors at room temperature, but at temperatures above 1000 to 1100°C, a portion decomposes and SiO ₂ is precipitated on the particle surface, but the inside of the particle is Decomposition is prevented by the SiO ₂ film on the surface. Therefore, BaTiO ₃ -based semiconductor powder and
When Ni ₃ Si, Ni ₅ Si ₂ , Ni ₃ Si ₂ , Ni ₂ Si or NiSi powder is mixed and fired, Ni ₃ Si, Ni ₅ Si ₂ , Ni ₃ Si ₂ ,
Ni ₂ Si or SiO ₂ precipitated on the surface of NiSi plays the same role as glass frit, and the inside of the particle plays the role of a conductive additive, so Ni ₃ Si, Ni ₅ Si ₂ , Ni ₃ Si ₂ ,
By simply adding Ni ₂ Si or NiSi, a thick film type positive characteristic semiconductor device that does not require a glass frit can be obtained.

Furthermore, by adding a conductive metal, thermal conductivity becomes better than glass frit which has poor thermal conductivity, and thermal shock resistance also improves.

DESCRIPTION OF EMBODIMENTS Examples of the present invention will be specifically explained below with reference to FIG.

Example 1 1.0 mol % of Nb ₂ O ₅ is added to BaTiO ₃ and fired at 1300°C, followed by pulverization to obtain BaTiO ₃ -based semiconductor powder. Based on the total weight of the BaTiO ₃ -based semiconductor powder
15.0% by weight of Ni ₃ Si powder is added and mixed uniformly, and α-terpineol is further added to form paste mixture 1.

On the other hand, on a substrate 2 made of Al ₂ O ₃ etc., a pair of electrodes 3 made of a conductive material such as Ag,
4, and apply the paste mixture 1 by screen printing or the like so that a portion of the electrodes 3 and 4 remain on the electrodes 3 and 4, and then heat the mixture from room temperature to
The temperature was raised to 1350°C at a heating rate of 10°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, 3.0 mol% of BaTiO ₃ was added.
Add La ₂ O ₃ and bake at 1250℃, then crush.
Obtain BaTiO ₃ based semiconductor powder. The BaTiO ₃ based semiconductor powder contains 5.0% by weight of Ni ₅ Si ₂ powder, 5.0% by weight of Ni ₃ Si ₂ powder and 10.0% by weight of NiSi based on the total weight.
Powder is added 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. to 10℃/
The temperature was raised to 1300°C at a heating rate of min, held for 30 minutes, and then allowed to 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 5.1KΩ/cm ² in Example 1 and 2.0KΩ/cm ² in Example 2, and the relationship between temperature and resistance value for each is as follows: It was as shown in Figure 2. Second
In the figure, A indicates the characteristics of the device obtained in Example 1, and B
is the characteristic in the case of Example 2.

Furthermore, even when Ni ₂ Si powder is added as a conductive metal, properties similar to those described above can be obtained;
It was confirmed through experiments that Ni ₃ Si, Ni ₅ Si ₂ , Ni ₃ Si ₂ , Ni ₂ Si, and NiSi have similar effects when added alone or in combination.

Effects of the Invention As described above, according to the manufacturing method of the present invention,
Ni ₃ Si, Ni ₅ Si ₂ , Ni ₃ Si ₂ , Ni ₂ Si or NiSi powder acts as both a conventional conductive additive and a glass frit, making it highly effective for electrical and physical connections. Therefore, a thick film type positive characteristic semiconductor device can be obtained without glass frit.

In addition, Ni ₃ Si, a conductive metal with good thermal conductivity, is used instead of glass frit, which has poor thermal conductivity.
By using Ni ₅ Si ₂ , Ni ₃ Si ₂ , Ni ₂ Si, and NiSi, thermal conductivity 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 BaTiO ₃ -based semiconductor powder may be used as long as it is made into a semiconductor by adding various additives to BaTiO ₃ . Also, Ni ₃ Si,
The reason for specifying the addition amount of Ni ₅ Si ₂ , Ni ₃ Si ₂ , Ni ₂ Si, and NiSi powder as 1 to 60% by weight based on the total weight is that if it is less than 1% by weight, the sheet resistance becomes too large and the heating element becomes This is because BaTiO ₃ powder cannot be physically fixed together, and on the other hand, if it exceeds 60% by weight, the area resistance becomes too small and the self-control property (PTC property) becomes small, making it unsuitable for a heating element. be. Furthermore, BaTiO ₃ -based semiconductor powder and Ni ₃ Si, Ni ₅ Si ₂ ,
An organic solvent (α-terpineol in the example) was used to make the Ni ₃ Si ₂ , Ni ₂ Si, and NiSi powders into a paste, but 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 device that does not require a glass frit, and its practical effects are great.

[Brief explanation of the drawing]

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] 1 BaTiO ₃ based semiconductor powder with Ni ₃ Si, Ni ₅ Si ₂ ,
It is characterized by adding 1.0 to 60.0% by weight of at least one of Ni ₃ Si ₂ , Ni ₂ Si, and NiSi, and applying the paste-like mixture onto a substrate to form a thick film, followed by firing. A method for manufacturing a thick film type positive characteristic semiconductor device.