JPS61101005A - Manufacture of thick film type 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 Elements made of BaTiO3-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 two external control ports.

Conventional positive temperature coefficient thermistor heating elements were obtained by press-molding B a T 103 semiconductor powder and then firing it, but it was difficult to obtain a practical thick film positive temperature coefficient thermistor heating element. It had been.

Conventionally, the following method is known as a method for processing a B a TiOs 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 using the vacuum evaporation method.

(2) Conductive additives and glass frit are added to B a TiOa semiconductor powder to form a paste, which is printed on a substrate as fleece and then fired.

However, in the method (2) above, since the crystal grain size of the B a T i O 3 -based semiconductor is large and brittle, it is extremely difficult to polish it into a film. In addition, the method (2) is cumbersome to operate, and it is difficult to obtain a large amount of power suitable for the heating element. Furthermore, the above method (3) 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. Depending on the material of the glass frit, B a T iO
It deteriorates the switching characteristics and self-heating characteristics of the III-based semiconductor. By adding a glass frit, the difference in heat resistance and coefficient of thermal expansion between the B a TiO3 semiconductor and the glass frit is small, making it susceptible to thermal shock and hindering 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 drawbacks of the prior art, which is the complexity of mud production, and creates a thick film with excellent thermal shock resistance and thermal conductivity by not 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 glue model positive characteristic semiconductor device of the present invention is based on B a
ZrB12 is added to TiO3-based semiconductor powder in a mixed amount of 1 to 60% by weight based on the total weight, and the paste-like mixture is applied onto a substrate to form a thick film, and then baked to form a thick film. The purpose is to obtain a type positive characteristic semiconductor device.

In the conventional method using conductive additives and glass frit, conductive additives are required to connect conductor powders between BaTi○3 semiconductor powder systems, and physical contact between BaTi○3 semiconductor powders is required. A glass frit was required to connect the

However, the present invention is characterized in that ZrB12 is used as a material that functions as both a conductive additive and a glass frit. This Z r B 1
2 is a conductor at room temperature, and when the temperature reaches 1oOO to 1100°C or higher, a portion of it decomposes and B2O3 is precipitated on the particle surface, but the inside of the particle remains as it was and decomposition is prevented by the BF2 film on the surface. Therefore, when B a TiO3-based semiconductor powder and ZrB12 powder are mixed and fired, Zr
B2O3 precipitated on the surface of B12 plays the same role as a glass frit, and the inside of the particle plays the role of a conductive additive, so just adding ZrB12 makes glass a thick film type positive temperature semiconductor that does not require a frit. An element is 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 is also improved.

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

Example 1.

1 for BaTiO3. Add o mol% Nb2O3 and 1
After firing at 3ω°C, it is pulverized to obtain a B a T iO3 semiconductor powder. ZrB12 powder in an amount of 12 parts by weight based on the total weight is added to the BaTiO3-based semiconductor powder and mixed uniformly, and then α-terpineol is added to prepare paste mixture 1.

On the other hand, a pair of electrodes 3.4 made of a conductive material such as Aq is provided on a substrate 2 made of Al2O3, etc., and a part of the electrodes 3.4 is left on the electrodes 3, 4. The paste-like mixture 1 was applied by screen printing or the like, and the mixture was heated from room temperature to 1061\.

The temperature was raised to 1360° C. at a heating rate of 1360° 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 La293 was added to B a T 103 and fired at 1260°C, followed by pulverization to obtain a BaTiO3-based semiconductor powder. Listening BaTi
ZrB of 28% by weight based on the total weight of O3-based semiconductor powder
12 powder is added and mixed uniformly, and a-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 room temperature 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, a thick film semiconductor device was obtained.

The sheet resistance at room temperature of the thick-film semiconductor device thus obtained was 3.4 Ω/cd in Example 1, and 1.1 Ω/crl in Example 2, and each temperature and resistance The relationship between the 7be2 values was as shown in Figure 2. In FIG. 2, A shows the characteristics of the device obtained in Example 1, and B shows the characteristics in Example 2.

Effects of the Invention As described above, according to the manufacturing method of the present invention, ZrB12 powder plays the role of both a conventional conductive additive and a glass frit, and has sufficient effects on electrical connection and physical connection. A thick film positive characteristic semiconductor element can be obtained without a glass frit.

By using ZrB12, a conductive metal with good thermal conductivity, instead of glass frit, which has poor thermal conductivity, thermal conductivity improves and thermal shock resistance improves. moreover,
Since it can be manufactured by screen printing, etc., it is easy to work with 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 BaTiO3. In addition, the addition amount of ZrB12 powder was specified to be 1 to 60% by weight relative to the total weight because if it was less than 1 weight range, the area resistance would be too large and it would be unsuitable for a heating element. On the other hand, if the weight ratio exceeds 60, the sheet resistance becomes too small, and the self-control characteristic (PTC characteristic) becomes small, making it unsuitable for a heating element. Furthermore, B a T
Although an organic solvent (alpha-terpineol in the example) was used to make the iO3-based semiconductor powder and the zrB12 powder into a paste, 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.
Its practical effects are significant.

[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. 1... Paste mixture 12... Substrate, 3, 4... Electrode. Name of agent: Patent attorney Toshio Nakao and 1 other person℃1
11 s kγ − , (1f)s kγ −

Claims (1)

[Claims] A thick film characterized by adding ZrB_1_2 to BaTiO_3-based semiconductor powder in a mixed 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. A method for manufacturing a film type positive characteristic semiconductor device.