JPS6158203A - 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 structure and its problems 13a Elements made of TiO3-based semiconductors have switching characteristics in which the resistance value increases rapidly above a predetermined temperature and self-heating characteristics after switching, and have fast temperature rise characteristics and a self-temperature control function. However, it is widely used because it does not require an external 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 a 3 aTio , -based semiconductor 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.

(13a) A conductive additive and glass frit are added to the 13a Ti03-based 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 13aTio-based semiconductor is large and brittle, it is extremely difficult to perform IR polishing to form 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, in method (2) above, the sheet resistance tends to be high, it is difficult to control, it generates dust, and it is not suitable for heating elements.Furthermore, the glass frit must be prepared and fired in advance, which is troublesome and the material of the glass frit is difficult to control. In some cases, the switching characteristics and self-heating characteristics of the BaTios half-core may be deteriorated. 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 impact resistance and thermal conductivity, and has a uniform 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.

[of the invention]j′G formation The method for manufacturing a thick film type positive characteristic semiconductor device of the present invention is based on BaT
yB2. to iO3-based semiconductor powder. YB4. YB6.
A thick-film type positive characteristic semiconductor element is obtained by applying a paste-like mixture of 1 to 60% by weight of at least one of YB and 2 on a substrate to form a thick film, and then firing it. That is.

In the conventional method using a conductive additive and glass frit, a conductive additive is required for electrical connection between BaTiO3-based semiconductor powders, and the BaT process requires a conductive additive. Glass frit was necessary to physically connect the comrades.

However, according to the present invention, YB2°YB4.
YB6. It is characterized by the use of YB,2. These YB2. YB4. YB6. YB, □
is a conductor at room temperature, but at temperatures above 1000-1100°C, a portion of it decomposes and 8203 is formed on the particle surface.
precipitates, but the inside of the particle remains intact and the surface 820
3 membranes prevent decomposition. Therefore, BaT engineering 0. based semiconductor powder, and YB2. YB4. YB6. YB,
2. When the powders are mixed and fired, YB2. YB4.
YB6. B2O3 precipitated on the surface of YB2.2 plays the same role as glass frit, and the inside of the particle plays the role of a conductive additive. YB4. YB6. YB
, □, a thick-film type positive characteristic semiconductor device that does not require a glass frit can be obtained.

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.

Actual gun example 1 BaT engineer 0. After adding 1.0 mol % of Nb2o5 and firing at 130°C, the mixture is pulverized to obtain BaTiO3-based semiconductor powder. YB4 powder in an amount of 12% by weight based on the total weight is added to the BaTi03 semiconductor powder 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 cardioelectric substance such as Ag is provided in advance on a substrate 2 made of A1゜03, etc., and a part of the electrodes 3゜4 remains on the electrodes 3 and 4. Apply the paste mixture 1 by screen printing or the like! The temperature was raised from room temperature 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 CeO2 was added to 13aTxO5, fired at 1260'C, and then crushed to form B.
Obtain aTyu03-based semiconductor powder. Said BaTyu 03
38% by weight of YB6 based on the total weight of the semiconductor powder
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. The temperature is raised from 10 to 1000°C at a heating rate of 10'C/min, held for 30 minutes, and then allowed to cool in the furnace. In this way, in the case of the thick film type half 2, the resistance was 0.4 Ω/cJ, and the relationship between each temperature and resistance value was as shown in FIG. In FIG. 2, A is the characteristic of the device obtained in Example 1, and B is
is the characteristic in the case of Example 2.

Effects of the Invention As described above, according to the manufacturing method of the present invention, YB2゜YB
4. YB6. YB,2 powder plays the role of both a conventional conductive additive and a glass frit, and has sufficient effects for electrical and physical connections, allowing thick film positive characteristic semiconductor devices to be obtained without a glass frit. It will be.

In addition, glass frit, which has poor thermal conductivity,
YB2. is a conductive metal with good thermal conductivity instead of K. YB
4゜YB6. By using YB,2, thermal conductivity is improved and thermal shock resistance is also improved. Furthermore, since it can be manufactured by free leaf printing, etc., the work is easy and mass production is possible.

In the present invention, any BaTi03-based semiconductor powder may be used as long as it can be made into a semiconductor by adding various additives to 13aTio5. Also, YB2゜YB4. YB6. YB, 2 The reason why the amount of powder added was specified as 1 to 60% by weight based on the total weight is because if it is less than 1% by weight, the area resistance becomes too large and it is 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 a heating element. Furthermore, BaTiO3-based semiconductor powder and YB, , YB4. YB6. An organic solvent (alpha-terpineol in the example) was used to make the YB, 2 powder into a paste, but any solvent may be used as long as it can be made into a paste. In addition, in the example, only one type of additive was shown, but it was confirmed that the same effect could be obtained even if multiple 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 significant.

[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. Name of agent: Patent attorney Toshio Nakao and 1 other list
1 Figure 2 Figure = e Chang/r (mc)

Claims (1)

[Claims] YB_2, YB_4, Y in BaTiO_3-based semiconductor powder
At least one type of B_6, YB_1_2
1. A method for manufacturing a thick-film type positive characteristic semiconductor device, comprising: applying a paste-like mixture to a substrate by adding ~60% by weight to form a thick film, and then firing the mixture.