JP3003359B2 - 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, an S which has 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.
An iC varistor and a ZnO-based varistor 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 and the common terminal 14 of the element 11 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 solder flows into a gap between a pin and an element, a voltage at which the varistor voltage does not change, the varistor voltage has no polarity, and the insulation resistance does not change. It is an object to provide a dependent nonlinear resistor porcelain element.

[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
Another electrode disposed on the peripheral surface, and disposed on the plane of the boundary.
And an electrode and a conductive adhesive disposed on the entire outer periphery.
And a common terminal electrically connected to the
An electrode provided on the entire inner circumference by a conductive adhesive
And a pin that is electrically connected .

[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 side
Of one end is larger 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 drying, it is baked at 1050 ° C. for 4 hours, pulverized 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 with a ball mill or the like for 24 hours, dried, and dried with polyvinyl alcohol or the like. After adding 10% by weight of an organic binder and granulating, a portion having a small outer diameter of the cylinder at a pressing pressure of 1 (t / cm ² ) has an outer diameter of 4 mm, an inner diameter of 1.4 mm, a height of 2.5 mm, and an outer diameter of the cylinder. The large part is formed into a cylindrical shape with an outer diameter of 6 mmφ, an inner diameter of 1.4 mmφ and a height of 0.5 mm,
Baking for 0 hours and debinding. 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. A conductive ohmic paste made of Zn or the like is provided on the inner peripheral surface of the element thus obtained by, for example, a roller transfer method, and the outer peripheral surface made of Zn or the like is obtained by removing a predetermined dimension from an end surface of a cylinder having a small outer diameter. The conductive ohmic paste is provided by a method such as roller transfer. Then at 120 ° C for 10
1 minute, and then a non-ohmic conductive paste is further provided thereon by a method such as roller transfer, dried at 120 ° C. for 10 minutes, and baked at 630 ° C. for 3 minutes, as shown in FIG. The voltage-dependent nonlinear resistor porcelain element 4 in which the electrode 1 and the electrode 2 are arranged on the element 3 is formed.

Next, as shown in FIG. 2, the pin 6 and the common terminal 9 are attached to the voltage-dependent nonlinear resistor porcelain element 4 with conductive adhesives 5, 8 such as solder, and a resin such as butadiene rubber is applied. Fill and heat cure.

(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. After a conductive ohmic paste made of Zn or the like is provided on the entire outer peripheral surface of the portion having a small diameter by, for example, a roller transfer method, the paste is dried at 120 ° C. for 10 minutes, and baked at 630 ° C. for 3 minutes. Next, the conductive portion is activated by a weak acid or the like, Cu plating / Ni plating is applied only to the portion activated by electroless, and electrolytic solder plating is further performed thereon to obtain electrodes 1 and 2 having a three-layer structure. . Next, similarly to the first embodiment shown in FIG. 2, the pins 6 and the common terminals 9 are attached with conductive adhesives 5 and 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 nonlinear resistor porcelain 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 has an effect superior to the conventional example in terms of the polarity of V1 _mA and the insulation resistance. can get.

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. Although only some of the plating components and combinations thereof are shown, any components can be used as long as similar effects can be obtained. The plating method may be electrolytic or electroless, and may be acidic plating, basic plating, or neutral plating. Further, it is possible to improve the noise elimination effect 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 the present embodiment, the entirety is cylindrical, and one end of the cylinder has a larger diameter than the other portion, and the length of the larger diameter cylinder is smaller than that of the other portion. It is shorter than the length of the cylinder, 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 outer peripheral surface excluding the dimension of the above, the electrode 1 on the inner periphery of the cylinder is integrated as one electrode, so that a conductive adhesive such as solder is provided in the gap between the pin 6 and the element 3. Even if 5 flows in, 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, and the insulation resistance does not change.

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, the adhesive force between the common terminal and the element can be increased, and the mechanical strength can be increased. Can be improved, and particularly, deterioration of characteristics due to a temperature cycle test can be reduced, and reliability can be improved.

In addition, even if excess conductive adhesive such as solder occurs, the apparent distance between the electrodes can be kept unchanged by stopping at the cylindrical portion having a large diameter. Further, even if the conductive adhesive such as solder falls on the outer periphery of the cylinder having a large diameter, it falls in the direction 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 the assembly is extremely small and stable is obtained,
The service life characteristics can be improved, and the 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 and the gap between the electrode 2 and the common terminal 9 are reduced, the conductive adhesive can be used. Even if it is not performed, the solder plating of the uppermost layer 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.

In order to sufficiently bring out the electrical characteristics of the element 3, one or more of Cu plating, Ni plating, Cr plating, Sn plating, Pb plating, Au plating, Ag plating, Pd plating and solder plating are required. By using a stacked type of electrode, the electrical characteristics of the device can be sufficiently brought out without forming a barrier at the interface between the device and the electrode, and it can be easily soldered to form multiple types of multilayer plating structures. Thereby, solder heat resistance can be improved. Although the length of the element is increased by making the element a cylindrical shape, the dimension in the radial direction of the element can be reduced, so that the pin interval of the connector can be reduced, and the size of the connector can be reduced. It is valid.

[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 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 an outer peripheral surface of the small-diameter cylinder by removing a predetermined dimension from an end surface thereof ;
Electrodes disposed on the plane of
Terminal that is electrically connected to the terminal using a conductive adhesive
And penetrating the through-hole, and the conductive adhesive
A voltage-dependent nonlinear resistor porcelain element comprising: an electrode provided on the entire peripheral surface; and a pin electrically connected to the electrode .