JPH04364B2 - - 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, which is a planar heating element used for heating, heating, etc. of equipment. It is.

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 manufacturing complexity that was a drawback of the prior art, and achieves excellent thermal shock resistance, thermal conductivity, and uniform characteristics 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 adding YSi, YSi ₂ , Y ₅ Si ₃ to BaTiO ₃ based semiconductor powder.
Thick-film positive temperature semiconductors are produced by applying a paste-like mixture of one or more types of powders in an amount of 1 to 60% by weight based on the total weight, forming a thick film on a substrate, and then firing it. The purpose is to obtain an element.

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, YSi, which functions as both a conductive additive and a glass frit,
It is characterized by the use of YSi ₂ or Y ₅ Si. These YSi, YSi ₂ and Y ₅ Si ₃ are conductors at room temperature, but at temperatures above 1000-1100°C, a portion decomposes and SiO ₂ precipitates on the particle surface, but the inside of the particle remains intact and the surface The SiO ₂ film prevents decomposition. Therefore, BaTiO ₃ -based semiconductor powder, YSi,
When YSi ₂ or Y ₅ Si ₃ powder is mixed and fired,
The SiO ₂ deposited on the surface of YSi, YSi ₂ or Y ₅ Si ₃ plays the same role as glass frit, and the inside of _the particles acts as a conductive additive.
By simply adding Y ₅ Si ₃ powder, it is possible to obtain a thick film type positive characteristic semiconductor device that does not require glass frit.

Furthermore, by adding a conductive metal, the thermal conductivity is improved compared to glass frit which has poor thermal conductivity, and the thermal shock resistance is also improved.

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

Example 1 1.0 mol % of SrO is added to BaTiO ₃ and fired at 1300°C, followed by pulverization to obtain BaTiO ₃ -based semiconductor powder.
20% by weight of YSi powder was added to the BaTiO ₃ semiconductor powder and mixed uniformly, and further α-
Add terpineol to make pasty 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, 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 heat the mixture from room temperature to
The temperature was raised to 1350°C at a heating rate of 10°C/min, kept 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.
After adding SrO and firing at 1250℃, crush
Obtain BaTiO ₃ -based semiconductor powder. 30% by weight of YSi ₂ powder based on the total weight is added to the BaTiO ₃ -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. The temperature was raised from 10°C to 1300°C at a 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 sheet resistance of the thus obtained thick film semiconductor device at room temperature was 1.2KΩ/cm ² in the case of Example 1, and 0.6KΩ/cm ² in the case of Example 2, and the relationship between each temperature and resistance value was was as shown in Figure 2. In FIG. 2, A is the characteristic of the device obtained in Example 1,
B is the characteristic in the case of Example 2.

Here, even when Y ₅ Si ₃ powder was used in place of the YSi and YSi ₂ powders, the same characteristics as in the above example could be obtained. Also, these YSi, YSi ₂ ,
It was confirmed that the same characteristics could be obtained when two or more types of Y ₅ Si ₃ powder were mixed and added. When one or more of these YSi, YSi ₂ or Y ₅ Si ₃ powders are added to BaTiO ₃ semiconductor powder in an amount of 1 to 60% by weight based on the total weight, a thickness with good properties can be obtained. A film type positive characteristic semiconductor device was obtained.

Effects of the Invention As described above, according to the manufacturing method of the present invention,
YSi, YSi ₂ , Y ₅ Si ₃ powders play both the roles of conventional conductive additives and glass frits, and have sufficient effects for electrical and physical connections, allowing thick film type positive properties without glass frits. A semiconductor element will be obtained.

In addition, YSi, a conductive metal with good heat conduction, is used instead of glass frit, which has poor heat conduction.
By using YSi ₂ and Y ₅ Si ₃ , 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 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, YSi,
Addition amount of YSi ₂ , Y ₅ Si ₃ powder is 1 to 1 to total weight
If it is outside the range of 60% by weight, if it is less than 1% by weight, the area resistance becomes too large and is not suitable for a heating element, and BaTiO ₃ powder cannot be physically fixed together.
On the other hand, if it exceeds 60% by weight, the sheet resistance becomes too small and the self-control characteristic (PTC characteristic) becomes small, making it unsuitable for a heating element. moreover,
_{An organic solvent (} in the example, α
- terpineol), 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, 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. DESCRIPTION OF SYMBOLS 1... Paste mixture, 2... Substrate, 3, 4... Electrode.

Claims (1)

[Claims] 1 YSi, YSi ₂ , Y ₅ Si ₃ in BaTiO ₃ -based semiconductor powder
Thick film type, characterized by adding one or more types of powder in an amount of 1 to 60% by weight based on the total weight, applying the paste-like mixture onto a substrate to form a thick film, and then firing. A method for manufacturing a positive characteristic semiconductor device.