JP3003361B2 - Voltage-dependent nonlinear resistor porcelain element - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a voltage-dependent non-linear resistor having a capacitor characteristic and a varistor characteristic for protecting a semiconductor and a circuit of a device from abnormal high voltage, noise, static electricity, etc. generated in an electric device or an electronic device. It relates to a body porcelain element.

[0002]

2. Description of the Related Art Conventionally, SiC having a voltage-dependent non-linear resistance characteristic for absorbing abnormal high voltage, eliminating noise, eliminating sparks, and taking measures against static electricity in various electric and electronic devices.
Varistors and ZnO-based varistors are used.
The voltage-current characteristics of such a varistor can be approximately expressed by the following equation.

[0003]

(Equation 1)

Here, I is a current, V is a voltage, C is a constant unique to a varistor, and α is a voltage-current nonlinear exponent.

[0005] α of a SiC varistor is 2 to 7, and α of some ZnO-based varistors reaches 50. Such varistors have excellent performance in absorbing relatively high voltage, but have little effect on absorbing relatively low voltage below varistor voltage due to low dielectric constant and small inherent capacitance. And the dielectric loss tan δ is as large as 5 to 10%.

On the other hand, to remove these low-voltage noises and the like, the apparent dielectric constant is about 5 × 10 ⁴ and tan δ is 1
% Of semiconductor capacitors are used. But,
When a voltage or current exceeding a certain limit is applied to such a semiconductor capacitor due to a surge or the like, the capacitance is reduced or destroyed, so that the semiconductor capacitor cannot function as a capacitor.

[0007] Therefore, recently, a device having SrTiO ₃ as a main component and having both varistor characteristics and capacitor characteristics has been developed. It is used to remove noise that enters from cables and connectors that connect devices to each other.

A conventional voltage-dependent non-resistive ceramic element having both characteristics of a varistor and a capacitor mainly composed of SrTiO ₃ will be described below.

As shown in FIG. 3, a voltage-dependent non-resistive porcelain element 10 used for removing noise entering from a connector or the like is a semiconductor ceramic having a voltage-dependent non-linear resistance characteristic mainly composed of SrTiO _3. An electrode 12 and an electrode 13 are provided on the upper and lower surfaces of a cylindrical element 11 made of.

As shown in FIG. 4, when the voltage-dependent non-resistive porcelain element 10 is incorporated in a connector, the conductive adhesive 1
At pins 6 and 17, the pin 15 and the electrode 12 of the element 11 and the common terminal 14 and the electrode 13 of the element 11 are bonded, respectively.
At this time, the conductive adhesive 1 is inserted into the gap between the pin 15 and the element 11.
6 may flow in.

[0011]

As described above, in the conventional configuration, the conductive adhesive 16 is provided in the gap between the pin 15 and the element 11.
Has a problem that the apparent distance between the electrodes decreases, the varistor voltage decreases, the varistor voltage becomes polar, and the insulation resistance decreases.

The present invention solves the above-mentioned conventional problems. Even if a part of the conductive adhesive flows into the gap between the pin and the element, the varistor voltage does not change and the varistor voltage does not have polarity. An object of the present invention is to provide a voltage-dependent nonlinear resistor porcelain element whose insulation resistance does not change.

[0013]

In order to achieve this object, a voltage-dependent nonlinear resistor porcelain element according to the present invention comprises a cylindrical through-hole at the center and two coaxial cylinders having different outer diameters on the same axis. The plane of the boundary between the two cylinders and the circle
The length of the larger diameter of the cylinder is shorter than the length of the smaller diameter
Voltage-dependent non-linear shape mainly composed of SrTiO ₃
A semiconductor ceramic having a resistance characteristic;
An inner circumferential electrode disposed on the entire inner circumferential surface of the through hole of Mick,
Another electrode disposed on the entire outer periphery of the small diameter cylinder,
Disposed on the plane of the boundary and disposed on the entire outer periphery
And an electrode that is electrically connected using a conductive adhesive.
Through terminal and the conductive adhesive through the through hole.
An electrode provided on the entire inner circumference and a pin for electrical connection
It is provided.

[0014]

According to this structure , the entire inner circumference of the semiconductor ceramic is
The electrodes arranged on the surface are integrated as one electrode
So, for example, conductive adhesion in the gap between the pin and the semiconductor ceramic
Even if the agent flows, the distance between the electrodes does not change. Ma
Also, provided on the outer peripheral surface of a small diameter cylinder of semiconductor ceramic
When connecting the electrode and the common terminal, use extra conductive adhesive
The sag can be stopped by a large-diameter cylinder.
The distance between the poles will not change. A cylinder with a large diameter
Even if the conductive adhesive drips around the outer periphery of the
Because it will hang in the direction away from the electrode
The distance between the electrodes does not change. The whole is cylindrical and one
Because the end is a cylinder with a larger diameter than the other end,
The surface insulation distance can be widened. Further common terminal
And provided on the outer peripheral surface of a small diameter cylinder of semiconductor ceramic
Easier connection to electrodes and higher adhesive strength
Can be Therefore, the varistor voltage decreases,
This prevents the insulation resistance from lowering due to the polarity.
Voltage-dependent voltage
It becomes a linear resistor porcelain element.

[0015]

【Example】

(Embodiment 1) Hereinafter, a first embodiment of the present invention will be described.

SrCO ₃ , CaCO ₃ , BaCO ₃ , Mg
CO ₃ and TiO ₂ are weighed at various composition ratios as shown in Table 1 and mixed by a ball mill or the like for 24 hours. Next, after drying, it is fired at 1050 ° C. for 4 hours, crushed again by a ball mill or the like for 24 hours, and dried to obtain a first component.

[0017]

[Table 1]

Next, the first, second and third components are weighed so as to have the composition ratios shown in the following (Table 1), mixed for 24 hours in a ball mill or the like, dried, and dried with polyvinyl alcohol. After adding 10% by weight of an organic binder such as the above and granulating, at a pressing pressure of 1 (t / cm ² ), the portion where the outer diameter of the cylinder is small is 4 mm in outer diameter, 1.4 mm in inner diameter, 2.5 mm in height, The portion having a large outer diameter of the cylinder is formed into a cylindrical shape having an outer diameter of 6 mmφ, an inner diameter of 1.4 mmφ, and a height of 0.5 mm, and is fired in air at 1200 ° C. for 10 hours to remove the binder. Next, firing is performed at 1425 ° C. for 5 hours in a reducing atmosphere, for example, a gas of N ₂ : H ₂ = 9: 1.

Thereafter, firing is performed at 1120 ° C. for 5 hours in an oxidizing atmosphere such as air. A conductive ohmic paste made of Zn or the like is disposed on the inner peripheral surface of the element body thus obtained by a method such as roller transfer, and a conductive ohmic paste made of Zn or the like is formed on the entire outer peripheral surface of the portion where the outer diameter of the cylinder is small. The paste is provided by a method such as roller transfer. Thereafter, the paste is dried at 120 ° C. for 10 minutes, and a non-ohmic conductive paste is similarly provided thereon by a method such as roller transfer.
After drying at 0 ° C. for 10 minutes and baking at 630 ° C. for 3 minutes, a voltage-dependent resistor porcelain element 4 in which the electrode 1 and the electrode 2 are arranged on the element 3 as shown in FIG. 1 is formed.

Next, as shown in FIG. 2, the pins 6 and the common terminals 9 are attached with the conductive adhesive 5 and the conductive adhesive 8, and a resin (not shown) such as butadiene rubber is filled and cured.

(Embodiment 2) A conductive ohmic paste made of Zn or the like is provided on the inner peripheral surface of the element obtained in the same manner as in the first embodiment by, for example, a roller transfer method. A conductive ohmic paste made of Zn or the like is provided on the entire outer peripheral surface of the portion having a small particle size by, for example, a roller transfer method, and then dried at 120 ° C. for 10 minutes and baked at 630 ° C. for 3 minutes. Next, the conductive part is activated by a weak acid or the like, and Cu plating and Ni plating are applied only to the part activated by electroless, and then electrolytic solder plating is further performed thereon to form a three-layer electrode 1 and an electrode 2. I do. Next, similarly to the first embodiment shown in FIG. 2, the pins 6 and the common terminals 9 are attached by the conductive adhesives 5, 8 such as solder, filled with a resin such as butadiene rubber, and cured by heating. The electrical characteristics of the thus obtained voltage-dependent resistor ceramic element alone and after assembling the connector are shown in (Table 2) and (Table 3), respectively.

[0022]

[Table 2]

[0023]

[Table 3]

V _{1mA in} Tables 2 and 3 is 1 m
A voltage across the element when current flows in the A, the polarity of V _1mA is a value obtained by dividing the difference between the positive direction of V _1mA and the negative direction of the V _1mA in the positive direction of V _1mA, insulation The resistance is an insulation resistance value between the pin 6 and the common terminal 9 when the applied voltage is 12 VDC. As is clear from Tables 2 and 3, the voltage-dependent nonlinear resistor porcelain element according to the present embodiment is superior to the conventional example in terms of the polarity of V1 _mA and the insulation resistance. Is obtained.

A part of the first component Sr is Ca, Ba,
Although only a part of the ratio of substitution with Mg is shown in the embodiment, any ratio may be used as long as the characteristics of the element are within a range having both varistor characteristics and capacitor characteristics at the same time. In the embodiment, the second component and the third component are shown only for some combinations. However, any components may be used as long as the components have a varistor characteristic and a capacitor characteristic at the same time. As the ohmic electrode, there are Ag, Cu, Ni, etc. other than Zn, but any other electrode may be used as long as an ohmic connection can be made at the interface between the element and the electrode. The plating method may be electrolytic or non-electrolytic, and may be acidic plating, basic plating, or neutral plating. In this embodiment, only some of the combinations of plating are shown, but any combination may be used as long as the same effect can be obtained. Further, the noise removing effect can be improved by connecting the voltage-dependent nonlinear resistor porcelain element to an inductance composed of, for example, a ferrite, a coil, a toroidal coil, or the like.

As described above, according to this embodiment, the entire cylinder is cylindrical, and one end of the cylinder is formed into a cylinder having a diameter larger than that of the other part, and the cylinder having the large diameter has a small diameter. Is formed to have a cylindrical through-hole at the center of the entire cylinder, and the electrode 1 is disposed on the entire inner peripheral surface of the through-hole. By disposing the electrode 2, the electrode 1 on the inner circumference of the cylinder is integrated as one electrode, so that the electrode 1 is integrated even if the conductive adhesive 5 such as solder flows into the gap between the pin 6 and the element 3. Since it is on the electrode 1, the apparent distance between the electrodes does not change. Therefore, the electrical characteristics are stable, the varistor voltage does not change,
The varistor voltage has no polarity and the insulation resistance does not change.

When the common terminal 9 is connected to the electrode 2 with a conductive adhesive 8 such as solder, the connection is easy, the adhesive force can be increased, and the excess amount of the conductive adhesive 8 such as solder can be reduced by a large diameter. By stopping at the cylindrical portion, the apparent distance between the electrodes can be kept unchanged.
A conductive adhesive 8 such as solder is applied to the outer periphery of the cylinder having a large diameter.
The apparent distance between the electrodes does not change, because even if it falls, it falls in the direction away from the electrode 1. Also, since the whole is cylindrical and one end of the cylinder is larger in diameter than the other parts, the surface insulation distance can be widened, so the electrical characteristics are stable, the varistor voltage does not change, and the varistor does not change. The polarity is not applied to the voltage, the insulation resistance does not change, and even if the element is assembled into a connector, the effect that the change in characteristics before and after assembling is extremely small and the effect is stabilized, and the application life characteristic can be improved, Reliability can be improved. Further, by forming the uppermost layer of the electrodes 1, 2 and the common terminal 9 by solder plating, for example, if the gap between the pin 6 and the electrode 1 or the gap between the electrode 2 and the common terminal 9 is reduced, the conductive adhesive 5 , 8 without heat treatment, only electrode 1,
The uppermost solder plating of the electrode 2 and the common terminal 9 can be melted and connected to each other. In order to sufficiently bring out the electrical characteristics of the element 3, Cu plating, Ni plating, C
r plating, Sn plating, Pb plating, Au plating, Ag
By forming one or more of the electrodes of plating, Pd plating, and solder plating on top of one another, the electrical characteristics of the element can be sufficiently obtained without forming a barrier at the interface between the element and the electrode. It can be easily attached, and the solder heat resistance can be improved by using a plurality of types of multilayer plating structures.

Although the length of the element is increased by making the element a cylindrical shape, the dimension of the element in the radial direction can be reduced, so that the pin interval of the connector can be reduced, and the connector can be reduced in size. It is effective to convert. In addition, by connecting the common terminal 9 to the electrode at the intermediate portion of the element 3, the height protruding from the common terminal 9 can be reduced, and the height can be reduced.

[0029]

According to the present invention, the semiconductor ceramic
The electrodes arranged on the entire inner circumference of the
Are inserted in the gap between the pin and the semiconductor ceramic.
Even if the conductive adhesive flows in, the distance between the electrodes does not change.
No. Also, on the outer peripheral surface of a small diameter cylinder of semiconductor ceramic
When connecting the provided electrode to the common terminal,
You can stop the dripping of the adhesive with a large diameter cylinder
Thus, the distance between the electrodes does not change. Temporarily large diameter
Even if the conductive adhesive drips around the outer circumference of the cylinder
Will hang down in the direction away from the electrodes on the surface.
Thus, the apparent distance between the electrodes does not change. Also, the whole is cylindrical
As a cylinder with one end larger in diameter than the other
Therefore, the surface insulation distance can be widened. Further
And a common terminal and the outer circumference of a small diameter ceramic semiconductor cylinder
Connection with the electrode provided on the surface becomes easy and the adhesive strength
Can also be increased. Therefore, the varistor voltage is low
To prevent insulation resistance from dropping due to
That have excellent electrical characteristics such as
It becomes a pressure-dependent nonlinear resistor porcelain element.

[Brief description of the drawings]

FIG. 1 is a sectional view of a voltage-dependent nonlinear resistor porcelain element according to an embodiment of the present invention.

FIG. 2 is a schematic sectional view when the voltage-dependent nonlinear resistor porcelain element is connected to a connector.

FIG. 3 is a cross-sectional view of a conventional voltage-dependent nonlinear resistor porcelain element.

FIG. 4 is a schematic cross-sectional view when the voltage-dependent nonlinear resistor porcelain element is connected to a connector.

[Explanation of symbols]

 1 electrode 2 electrodes 3 elements

Claims (1)

(57) [Claims] At the center, there are two cylindrical cylinders having different outer diameters coaxially with a cylindrical through hole at the center and a plane at the boundary between the two cylinders, and the length of the larger diameter of the cylinder a semiconductor ceramic having a voltage-dependent nonlinear resistance characteristics mainly composed of SrTiO ₃ in a shorter form than the length in the direction of smaller diameter, the electrode disposed on the inner peripheral entire surface of the through-hole of the semiconductor ceramic, Another electrode disposed on the entire outer periphery of the small diameter cylinder, and another electrode disposed on the plane of the boundary and
The electrodes are placed on the entire outer circumference and the electricity is
And a common terminal that is electrically connected to
It electrically connects with the electrode provided on the entire inner circumference by the electrically conductive adhesive.
Voltage-dependent non-linear resistor porcelain element comprising a connecting pin .