JPS62190815A - Manufacture of voltage nonlinear device - 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 voltage nonlinear element whose resistance value changes depending on an applied voltage, and is useful for voltage stabilization, abnormal voltage control, and matrix-driven liquid crystal, KL, etc. It is used in switching elements of display devices, etc.

Conventional technology Conventional voltage nonlinear elements are made of zinc oxide (ZnO), bismuth oxide (Bi20.), and cobalt oxide (CO203).
, manganese oxide (Mn02), antimony oxide (sb2)
03) and other oxides at 1000-1350°C.
There are various types of varistors such as ZnO varistors sintered with Among them, ZnO varistors are most commonly used because of their large voltage nonlinearity index α and surge resistance. (Refer to Japanese Patent Publication No. 46-19472.) Problems to be Solved by the Invention Conventional voltage non-linear devices, such as ZnO varistors, have a limited thickness (less than several tens of micrometers). Therefore, the varistor voltage (current 1m in the varistor)
There is a limit to the ability to lower the voltage (expressed as v+mA) when a current is applied, and it cannot be used as a low-voltage 1G protection element or a voltage stabilizing element at low voltages. Further, as mentioned above, since a high temperature process of 100° C. or more is required during firing, there is a problem that a voltage nonlinear element cannot be directly formed on a glass substrate or a circuit board. Furthermore, conventional devices have a large parallel capacitance, making them unsuitable for use as switching elements for liquid crystals, for example.

Means for Solving the Problem In order to solve this problem, the present invention adds an inorganic or organic compound containing Sb to a fine powder of an inorganic semiconductor, and after mixing, heat-treats at 6oO to 136°C. and
An inorganic insulating film is formed on the surface of the inorganic semiconductor fine powder, and all or most of the fine powdered inorganic semiconductors having the insulating film on the surface are gathered together, and then the fine powder is An insulating organic adhesive or glass powder and an organic binder are added to a powder in which a plurality of inorganic semiconductors are assembled or a part of the powder contains the above-mentioned fine powder to form a paint, and then the paint is applied to an electrode. It is characterized in that it is applied onto an insulated substrate by printing, spraying, dipping, etc., and then heat-treated to harden it.

Effect: According to this method, a large voltage non-linearity index α can be obtained even in a low current range, and an element can be formed with a narrow distance between electrodes (several tens of μm or less), making it possible to reduce the voltage. Suitable elements will be obtained very easily. Furthermore, since it can be made by curing the applied paint at a low temperature, it is possible to form elements directly on a circuit board, and it is expected to have a wide range of applications unimaginable for ZnO varistors and the like. Furthermore, since the obtained device is made of solidified semiconductor material in the form of fine powder, there is point contact between the fine powders of each semiconductor material, and the contact area is small, making it possible to obtain a device with a small parallel capacitance. , it is possible to provide an element that is optimal as a switching element for devices such as liquid crystals.

Example Hereinafter, the present invention will be explained in detail based on examples.

FIG. 1 shows an embodiment of the manufacturing process according to the manufacturing method of the present invention. First, fine particulate zinc oxide with a particle size of 0.06 to 1 μm is fired at ~1300°C, and then the sintered ZnO is sintered with a particle size of 0.5 to 50 μm (average particle size of 1 to 10 μm). 0.05 to 10 mOl % of antimony oxide was added to the ZnO powder and heat treated at 600 to 1350°C for 10 to 60 minutes to form an insulating film of antimony oxide on the surface of the fine ZnO powder. . At this time, sb 20 is present on the surface of the fine powder ZnO.
It was observed that the insulating coating was formed thinly, with a thickness of approximately several tens to several hundreds. Next, 5b20. created in this way. Since the ZnO fine powders with the insulating coating attached to their surfaces adhered to each other with weak force, they were loosened using a mortar or a bot mill to form a fine powder group in which a plurality of each of the above Zno fine powders were gathered (hereinafter, this state will be referred to as powder).

At this time, there is no problem even if the ZnO fine powder is present alone in a part, and a state containing such ZnO fine powder in a part is also referred to as powder.

Next, a polyimide resin was added as a binder for bonding the powders to the powdered ZnO on which the 5b203 insulating film obtained as described above was formed and mixed. Here, the binder is a polyimide resin diluted so that the solid content is Swt% with respect to the solvent (for example, n-methyl-2-pyrrolidone), and it is
For example, it was mixed with nO powder in an equal weight to form a paint.

Next, the paint obtained as described above is applied, for example, by screen printing, onto a glass substrate 3 on which an ITO (indium tin oxide) electrode 1 is provided, as shown in FIG. The glass substrate 4 provided with the τ0 electrode 2 was mounted and cured in the atmosphere at 280 to 400'C for 30 minutes, and a voltage nonlinear element 6 was provided between the electrodes 1 and 2. FIG. 2 is an enlarged cross-sectional view of the voltage nonlinear element 5, in which 6 is a ZnO powder, 7 is a 9b 203 insulating coating applied to the surface of the ZnO powder 6, and 8 is a mechanical layer between the ZnO powders 6. This binder 8 binds the ZnO powders 6 together. FIG. 4 shows a glass substrate 3&on which ITO electrodes 11L and 1b are provided.
A case in which a voltage nonlinear element 6 is configured is shown above.

Next, the voltage-current characteristics of the voltage nonlinear element created as described above will be explained. First, Figure 6 shows the 3rd
The voltage-current characteristics of the configuration shown in the figure are compared with those of a conventional ZnO varistor.

The element of the present invention is produced by first firing zinc oxide at 700°C,
Added 5b203 to this at 1% smo and added 9
After heat treatment at 00°C for 60 minutes, this average particle size is 6~
The characteristics are shown in a case where a 10 μm thick ZnO powder and a binder are mixed in equal weight, and the element area is set to 30 μm and the distance between the 1st and 2nd electrodes is 30 μm. Now, as is well known, the voltage-current characteristics of a voltage nonlinear element are approximately expressed by the following equation.

I=KV" Here, Δ is the current flowing through the element, V is the voltage between the electrodes of the element, K is a constant corresponding to the resistance value of the specific resistance, and α is the exponent of the voltage nonlinear characteristic mentioned above. , the larger the voltage nonlinearity index α, the better the voltage nonlinearity.

As shown in the characteristics in Figure 6, the conventional ZnO varistor shown in characteristic B has a voltage nonlinearity index α in the low current range
is small, and cannot function as a good voltage nonlinear element at a current of 10-45 or less. On the other hand, in the device of the present invention shown in the characteristics, the voltage nonlinearity index α is large even in the low current range, and it can sufficiently function as a voltage nonlinear device even in the current range of about 10-105. It shows. In addition, normally, in order to express the varistor characteristics of a ZnO varistor, for example, the voltage that appears between the electrodes when a current of 1 mm is passed through the element is called the varistor voltage v.
This varistor voltage of 7111 mm and the voltage non-linearity index α are used. As mentioned above, in the device of the present invention, the voltage non-linearity index α is large even in the low current range, and the varistor voltage is, for example, 71 as shown in FIG.
Can be expressed by one person.

In this way, in the present invention, the varistor voltage can be made low because the element can be formed by narrowing the distance between the electrodes.

Furthermore, the reason why the voltage nonlinearity index α is large even in the low current range in the device of the present invention is not clear at present, but it is because the powdered semiconductor material (ZnO) is hardened with a binder. This is thought to be due to the fact that there is a point contact between the respective semiconductor materials, and the contact area is small, and the bonding agent is insulating, so the leakage current is small.

Here, the characteristics shown in FIG. 6 are as follows when the distance between the electrodes is 3
This is for an element with a thickness of 0 μm;
This is because the average particle diameter of the O powder is relatively large, 5 to 10 μm, and cannot be made any narrower. That is, the average particle diameter of the ZnO powder is 0.3 to 3
If a micrometer electrode is used, it is possible to create an element with an interelectrode distance of about 10 μm or less, and the inventors have demonstrated that even in that case, good characteristics as shown in FIG. 6 can be obtained. was confirmed by experiment.

FIG. 6 shows how the varistor voltage v, 1 μm, voltage nonlinearity index α, and parallel capacitance C change when the amount of antimony oxide added is changed in the present invention. Here, other conditions such as the firing temperature of zinc oxide were the same as those in the case of FIG. 5.

As shown in FIG. 6, in the device of the present invention, the parallel capacitance is 1000 to 20000 compared to that of the conventional ZnO varistor.
Although it is a PF, it is very small.

The reason why this parallel capacitance C is small in the device of the present invention is that the contact area between the semiconductor materials is small, as described above.

Table 1 also shows that the varistor voltage v<11 μm when the amount of antimony oxide added and the heat treatment temperature are changed in the present invention.
2 is a table showing how the voltage nonlinear index α and the parallel capacitance C change.

(Left below) As is clear from Table 1 and FIG. 6 above, each characteristic value is dependent on the amount of antimony oxide added and the heat treatment temperature. Here, the amount of antimony oxide added is 0.
Particularly good characteristics were shown in the range of 06 to 3m01%. In addition, the heat treatment temperature depends on the amount of antimony oxide added, but
It showed good characteristics in the range of ~1350'C. If the heat treatment temperature is outside the above temperature range, for example below 600°C, it may be difficult to form a sufficient insulating film;
At temperatures exceeding t-, good characteristics cannot be obtained because the voltage nonlinearity index α becomes less than the required value.

In addition, in the above implementation series, the semiconductor material is
Although ZnO is used in the explanation, it goes without saying that other semiconductor materials may be used. Similarly, the material constituting the insulating film is not limited to 5b203 alone, but 5b20. As the main component, mul
, Ti, Sr, Mg, Ni.

Metal oxides such as Or and Si or organometallic compounds of these metals can be used alone or in combination.

Furthermore, as a binder for solidifying powdered semiconductor materials,
Insulating organic adhesives other than polyimide resins may also be used, such as thermosetting resins such as phenolic resins, furan resins, area resins, and melamine resins.

Unsaturated polyester resins, diallyl phthalate resins, epoxy resins, polyurethane resins, silicone resins, etc. may be used, and furthermore, a combination of glass powder and an organic binder may be used.

In addition, in the above embodiments, the elements were formed by screen printing, but other coating methods such as spraying,
A method such as immersion may also be used.

Furthermore, in the manufacturing method according to the above embodiment, first, ZnO in the form of fine particles, which is an inorganic semiconductor, is heat-treated and pulverized to powder, and then 5b, which is an insulating inorganic compound, is
2o5 was added and then heat treated, but it is possible to add the inorganic compound directly to the fine powder of the inorganic semiconductor and omit the processing steps of firing and pulverizing the inorganic semiconductor particles. be.

Effects of the Invention As is clear from the above explanation, the voltage nonlinear element obtained by the method of the present invention has a large voltage nonlinearity index α in the low current region, and an element with small parallel capacitance. Therefore, it is possible to provide an element that is optimal as a switching element for devices such as liquid crystals and gLs with low current consumption. In addition, since the device can be formed with a narrower distance between the electrodes, a device with a lower varistor voltage can be obtained.
Combined with the large voltage nonlinearity index α mentioned above, the conventional Z
It can be used as a protection element for low-voltage ICs or as a voltage stabilizing element at low voltages, which could not be done with nO varistors. Furthermore, since the applied paint can be easily manufactured by curing at a low temperature, elements can be directly formed on circuit boards or glass substrates. The voltage non-linear element of the present invention having such various characteristics can be expected to have a wide range of applications unimaginable for conventional ZnO varistors and the like, and its industrial applicability is excellent.

[Brief explanation of drawings]

FIG. 1 is a diagram showing the steps of a method for manufacturing a voltage nonlinear element according to the method of the present invention, and FIG. 2 is an enlarged sectional view showing an example of a voltage nonlinear element obtained by the method of the present invention. 3 and 4 are cross-sectional views showing examples in which the device of the present invention is provided on a glass substrate, respectively, and FIG. 5 shows the voltage-current characteristics of the device obtained by the method of the present invention and a conventional ZnO varistor. The figure shown in FIG. 6 is 5b2 in the device according to the method of the present invention.
FIG. 3 is a diagram showing how the voltage non-linearity index α, the varistor voltage v11m, and the parallel capacitance C change when the amount of addition of 05 is changed. 1.1rh, 1b, 2---ITO electrode, 3,3
a. 4...Glass substrate, 5...Voltage nonlinear element, 6...ZnO powder, 7...5
b205 Insulating coating, 8...Binder. Name of agent: Patent attorney Toshio Nakao and 1 other foam agent
1 Figure 2 Electrode 5 Figure 5 Single force Voltage (v) Figure 6

Claims (1)

[Claims] After adding and mixing an inorganic or organic compound containing Sb to a fine powder of an inorganic semiconductor, heat treatment is performed at 600 to 1350°C to form an inorganic insulating film on the surface of the fine inorganic semiconductor powder. All or most of the finely powdered inorganic semiconductors on the surface are brought together into a plurality of pieces, and then the fine powder is applied to the powder or a part of the finely powdered inorganic semiconductors. An insulating organic adhesive or glass powder and an organic binder are added to the powder containing the powder to form a paint, and the paint is then applied by printing, spraying or dipping onto an insulating substrate on which electrodes are arranged, followed by heat treatment. A method for manufacturing a voltage nonlinear element, the method comprising curing the element.