JPS59208803A - 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 Elements made of BaTiO s optical semiconductors have a null isostatic characteristic in which the resistance value increases rapidly when the temperature exceeds a predetermined temperature, and a self-heating characteristic after switching. It is widely used because it has a control function and does not require an external control circuit.

Conventional positive temperature coefficient therminuta heating elements were obtained by press-molding BaTiOs semiconductor powder and then firing it, but in order to heat a large area, it required a large number of elements, was large and difficult to assemble, and was difficult to assemble. It has been believed that it is difficult to obtain a practically usable thick film type PTC heating element.

Conventionally, the following method is known for processing a BaTi03 medium conductor into a film shape. The material is formed into a disk shape, fired, and then polished into a thin piece.

■ Form a thin film on a substrate using vacuum evaporation method, Suba Tsukling method, etc.

(2) A conductive additive and glass frit are added to the BaTi0s optical semiconductor 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 BaTiO3-based semiconductor is large and brittle, it is extremely difficult to polish it into a film with a knife. -1: The above method (2) is troublesome to operate, cannot be used with large-area elements, and is difficult to obtain a large amount of power suitable for a heating element.

Furthermore, the above-mentioned method (2) tends to have a high sheet resistance, making it difficult to control the resistance value, and is not suitable for heating elements.

Unfortunately, the glass frit must be made in advance, which is troublesome and, depending on the material of the glass frit, may deteriorate the switching characteristics and self-heating characteristics of the BaTiOx semiconductor. By adding glass frit, it is susceptible to thermal shock due to the difference in heat resistance and coefficient of thermal expansion between BaTiO3 semiconductor and glass frit, and thermal conductivity tends to deteriorate, resulting in a lack of reliability. Furthermore, it is difficult to uniformly mix the conductive additive and the glass frit, which is one of the causes of variations in properties.

As described above, there has been no conventional method for obtaining a thick film type positive temperature semiconductor element suitable for a planar heating element.

Purpose of the Invention Therefore, the present invention solves the manufacturing complexity that was a drawback of the prior art, and by using a thick film type without using glass frit, it has excellent thermal shock resistance and thermal conductivity, and has uniform properties. The purpose of the present invention is to provide a method for easily manufacturing a thick-film type positive characteristic semiconductor device having the following characteristics.

Structure of the Invention In order to achieve this object, the method of manufacturing a thick film type positive temperature semiconductor device of the present invention includes adding a predetermined amount of W2B5 to an E+aTiC1-based semiconductor and applying a paste-like mixture onto a substrate to form a thick film. The purpose is to obtain a thick film type positive characteristic semiconductor element by forming a mold and firing it. 0 A method using conventional conductive additives and glass flint.

In this method, a conductive additive was required for electrical connection between BaTiOx-based semiconductor powders, and a glass frit was required to physically connect the BaTiOx-based semiconductor powders. However, according to the present invention, thickening of the film is possible using only W2B5, which acts as both a conductive additive and a glass frit. That is, W2B5 is a conductor at room temperature, but at a high temperature of 1100° C. or higher, a portion of it decomposes and 820 g is precipitated on the particle surface. The inside of the particle is decomposed by the B2O3 layer.

Protected from oxidation and remains up to the size of W2B5. Therefore, +
When 3aTiQB semiconductor powder and W2B5 are mixed and fired, the B2Qx precipitated on the surface of the W2B5 powder plays the same role as a glass frit and binds to the open collar of the powder particles, and the unreacted W2B5 inside the particles becomes a conductive additive. fulfill one's role.

Therefore, by simply adding W2B5, it is possible to obtain a thick film type positive characteristic semiconductor element that does not require a glass frit.

Description of examples The present invention will be specifically described below with reference to Examples.

Example 1 3.01001% SrO was added to BaTiOs, mixed by pulverization using a ball mill, etc., dried, and fired at 1300° C. for 1 hour. After that, BaT is crushed with a ball mill etc.
An iO3-based semiconductor powder is obtained. 10% by weight of W2B5 based on the total weight is added to the BaTiQB-based semiconductor powder, ground and mixed using a ball mill, etc. After drying, α-terpineol, polyethylene glycol, etc. are added to form a paste-like mixture. Then, as shown in Figure 1, A4203
A pair of electrodes 3 and 4 made of a conductive substance such as HG are provided in advance on a substrate 2 made of
, 4 by screen printing or the like so that a portion of the electrodes 3, 4 are exposed,
139°C4 at a heating rate of 10°C/min from room temperature
After heating and holding for 1 hour, let it cool in the furnace.

Example 2 In the same manner as in Example 1, 30 mo and 5% pbo were added to BaTiO3, baked at 1250°C for 1 hour, and then ground.
After adding 45% by weight of W2B5 based on the total weight, mixing, pulverizing and drying, polyvinyl butyral, octyl phthalate, etc. are added to form a paste mixture. Thereafter, the paste-like tetracompound was screen printed in the same manner as in Example 1, and then baked and allowed to cool.

The sheet resistance of the thus obtained thick film semiconductor element at 25°C is 360Ω/Cr in the case of Example 1. In the case of Example 2, it was 12Ω/d. Moreover, the relationship between each temperature and resistance value was as shown in FIG. In FIG. 2, A and B each show the characteristics of Example 1.

Effects of the Invention The present invention is configured as described above, and W2
B5 powder plays the role of both a conventional conductive additive and a glass frit, and has sufficient effects for electrical connection and physical connection between particles, and can be used for thick film type positive temperature semiconductor devices without glass frit. is obtained.

Furthermore, by using W2B5, which has excellent thermal conductivity and electrical conductivity, instead of glass 7-linoto, which has poor thermal conductivity, thermal conductivity is improved and thermal shock resistance is also improved. Furthermore, since it can be manufactured using methods such as screen printing,
It is easy to work, can be made into a large area, and can be mass-produced.

In addition, in the present invention, the BaTi0g-based semiconductor includes:
Anything is possible as long as it is made into a semiconductor by adding various additives to BaTiOs.

Also, the mixing amount of W2B5 was 1. ○〜60
．． The reason why Ba
This is because TiOs particles cannot be physically fixed and become brittle. This is because, 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.

Further, although an organic solvent was used to make the BaTiOs semiconductor and the W2B5 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 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] The amount mixed in BaTiOs semiconductor is 1.0 based on the total weight.
1. A method for manufacturing a thick-film type positive characteristic semiconductor device, comprising: applying a paste-like mixture of W2Bs of ~60.0 weight factor to a substrate to form a thick film, and then firing the mixture.