JP3003362B2 - 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 nonlinear resistor 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 nonlinear resistor porcelain element 10 used for removing noise entering from a connector or the like is a semiconductor having a voltage-dependent nonlinear 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 ceramic.

As shown in FIG. 4, when the voltage-dependent nonlinear resistor porcelain element 10 is incorporated in a connector, the pins 15 and the electrodes 12 of the element 11 and the common terminals 14 and The electrodes 13 are respectively bonded. At this time, a part of the conductive adhesive 16 may flow into the gap between the pin 15 and the element 11.

[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 terminal, the varistor voltage does not change, the varistor voltage does not have polarity, and the insulation resistance does not change. It is an object of the present invention to provide a voltage-dependent nonlinear resistor porcelain element in which the voltage 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,
The outside of the small-diameter cylinder excluding a predetermined dimension from the end face
An electrode disposed on a peripheral surface and the plane of the boundary;
Electrodes and the electrodes arranged on the entire outer periphery.
A common terminal that is electrically connected using an electrically conductive adhesive;
Penetrate through the through-hole and use a conductive adhesive to cover the entire inner periphery.
And a pin that is electrically connected to the electrode provided in the above.

[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. In addition, the whole is cylindrical
One end has a larger diameter than the other end.
Thus, the surface insulation distance can be widened. More common
Terminal and the outer peripheral surface of a small diameter cylinder of semiconductor ceramic.
Easier connection to girder electrodes and higher adhesive strength
Can be done. Therefore, the varistor voltage has decreased
To prevent insulation resistance from becoming low due to polarity.
Voltage dependence with excellent electrical characteristics such as charging life characteristics
Becomes a non-linear resistor ceramic 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 the following (Table 1), and mixed by a ball mill or the like for 24 hours.

[0017]

[Table 1]

Next, after being dried, it is baked 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. Next, the first component, the second component, and the third component are weighed so as to have the composition ratios shown in (Table 1), mixed for 24 hours in a ball mill or the like, dried, and then dried with an organic binder such as polyvinyl alcohol. After adding 10% by weight and granulating, under a pressing pressure of 1 (ton / cm ² ), the portion having a small outer diameter of the cylinder has an outer diameter of 4 mmφ, an inner diameter of 1.4 mmφ,
2.5mm height, 6mm outer diameter at the part where the outer diameter of the cylinder is large
φ, inner diameter 1.4mmφ, height 0.5mm into a cylindrical shape,
It is calcined at 1200 ° C. for 10 hours in air 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. After that, firing is performed at 1120 ° C. for 5 hours in an oxidizing atmosphere such as air. An electrode in which a conductive ohmic paste made of Zn or the like is disposed on the inner peripheral surface of the element thus obtained by, for example, a roller transfer method, is provided on an outer peripheral surface obtained by removing a predetermined dimension from an end surface of a cylinder having a small outer peripheral diameter. A conductive ohmic paste made of Zn or the like is disposed by a method such as roller transfer, and a conductive ohmic paste made of Zn or the like is placed on a plane where a large-diameter cylinder is in contact with a small-diameter outer cylinder, for example, by roller transfer. Another electrode provided by the method is provided. Thereafter, dried at 120 ° C. for 10 minutes, and a non-ohmic conductive paste is further provided thereon by a method such as roller transfer in the same manner,
After drying at 120 ° C. for 10 minutes and baking at 630 ° C. for 3 minutes, as shown in FIG. 1, a voltage-dependent nonlinear resistor porcelain element 4 in which an electrode 1 and an electrode 2 are arranged on an element 3 is formed.

Next, as shown in FIG. 2, the pin 6 and the common terminal 9 are attached to the voltage-dependent non-linear resistor ceramic element 4 with conductive adhesives 5 and 8 such as solder, and a resin such as butadiene rubber (see FIG. 2). (Not shown) and cured by heating.

(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, for example, by a method such as roller transfer.
A conductive ohmic paste made of Zn or the like is disposed on the outer peripheral surface of the cylinder having a smaller outer diameter except for a predetermined dimension from an end surface thereof by, for example, a roller transfer method, and a cylinder having a larger diameter contacts a cylinder having a smaller outer diameter. After a conductive ohmic paste made of Zn or the like is provided as another electrode on a plane by a method such as roller transfer, for example, 120
Dry at 10 ° C. for 10 minutes and bake at 630 ° C. for 3 minutes.

Next, the conductive portion is activated with a weak acid or the like, and Cu plating, N
i-plating, then electrolytic solder plating on it,
The electrodes 1 and 2 have a three-layer structure. Next, similarly to the first embodiment shown in FIG.
The pin 6 and the common terminal 9 are attached by 8 and filled with a resin such as butadiene rubber and cured by heating. The electrical characteristics of the voltage-dependent nonlinear resistor porcelain element thus obtained and the electrical characteristics after assembling the connector are shown in Table 2 respectively.
And (Table 3).

[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 the positive direction of V _1mA and the negative direction of the V _1mA
Is the value obtained by dividing the difference by ₁ V in the positive direction.
This is the 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,
In the case of substituting with Mg, only a part is shown in the embodiment, but any element may be used as long as the element has a varistor characteristic and a capacitor characteristic 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 established at the interface between the element and the electrode. Although only some of the plating components and their combinations are shown, any combination may be used as long as the same effects can be obtained. The plating method may be electrolytic or electroless, and may be acidic plating, basic plating, or neutral plating. Further, a configuration in which an inductance made of, for example, a ferrite, a coil, a toroidal coil, or the like is connected to the voltage-dependent nonlinear resistor porcelain element can improve the noise removal effect.

As described above, according to the embodiment, the entire cylinder is cylindrical, and one end of the cylinder has a cylindrical shape with a diameter larger than that of the other portion, and the length of the large-diameter cylinder is small. It is shorter than the length, is formed so as 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 arranging the electrode 2 on the plane of the boundary where the outer peripheral surface, the large-diameter cylinder and the small-diameter cylinder contact each other, the electrode 1 on the inner circumference of the cylinder is integrated as one electrode. Even if the conductive adhesive 5 such as solder flows into the gap between the electrode 3 and the element 3, the apparent distance between the electrodes does not change because it is on the integrated electrode 1. Therefore, the electrical characteristics are stable, the varistor voltage does not change, the varistor voltage has no polarity,
The insulation resistance does not change.

Further, since the surface space insulation distance between the electrode 1 and the electrode 2 is increased, the electrical characteristics are more stable.

Further, when the common terminal 9 is connected to the electrode 2 with the conductive adhesive 8, the contact area becomes large, the connection is easy, and the common terminal 9 can be connected from the upper and lower directions. It is possible to increase the adhesive strength between the element 3 and the element 3, improve the mechanical strength, reduce the deterioration of characteristics due to a temperature cycle test, and improve the reliability. In addition, even if the conductive adhesive 8 such as excess solder is dripped, the apparent distance between the electrodes can be kept unchanged by stopping at the large-diameter cylindrical portion. In addition, even if the conductive adhesive 8 such as solder spills on the outer periphery of the cylinder having a large diameter, it spills away from the electrode 1, so that the apparent distance between the electrodes does not change. 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.
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 8 The solder plating of the uppermost layers of the electrode 1, the electrode 2, and the common terminal 9 can be melted and connected to each other only by performing the heat treatment even if there is no heat treatment. In order to sufficiently bring out the electrical characteristics of the element 3, Cu plating, Ni plating, Cr plating,
Sn plating, Pb plating, Au plating, Ag plating, P
By using an electrode in which one or more of d-plating and solder plating are stacked, the electrical characteristics of the element can be sufficiently brought out without forming a barrier at the interface between the element and the electrode, and the soldering can be easily performed. By using a plurality of types of multilayer plating structures, solder heat resistance can be improved.

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. It is effective for downsizing.

[0030]

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. The whole is cylindrical
And one end of the cylinder is larger in diameter than the other end.
Therefore, the surface insulation distance can be widened. further
Common terminal and outer peripheral surface of small diameter cylinder of semiconductor ceramic
Connection with the electrode provided on
Can be bigger. Therefore, the varistor voltage is low.
To prevent insulation resistance from becoming low due to
Can be a voltage with excellent electrical characteristics such as charging life characteristics
It becomes a 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, Electrodes disposed on an outer peripheral surface obtained by removing a predetermined dimension from an end surface of the small diameter cylinder and the plane of the boundary, and disposed on the boundary plane and over the entire outer peripheral surface.
It is electrically connected to the arranged electrodes using conductive adhesive.
Common terminal and a conductive adhesive through the through hole.
More electrically connected to an electrode provided on the entire inner circumference
And a voltage-dependent non-linear resistor porcelain element.