JPH05251215A - Voltage dependent non-linear resistor ceramic element - Google Patents

Abstract

PURPOSE:To enhance the reliability by stabilizing the electric characteristics even if a conductive bonding agent runs into the gap between a connector pin and an element within the title voltage dependent non-linear resistor ceramic element having the capacitor characteristics and varistor characteristics for protecting the semiconductor and circuits of equipment from abnormal high voltage, noise, static electricity, etc., generated from an electric equipment. CONSTITUTION:Within a voltage dependent non-linear resistor ceramic element, a semiconductor ceramics mainly comprising SrTiO3 having the voltage dependent non- linear resistance characteristics takes the shape wherein two coaxial cylinders in different outer peripheral diameters with the length of the cylinder in larger diameter shorter than that of the cylinder in smaller diameter having a cylindrical through hole in the central part of the whole cylinder while an electrode is arranged on the whole inner peripheral surfaces of the through hole and then the other electrodes are arranged on the outer peripheral surfaces of the cylinders in smaller outer peripheral diameter. Through these procedures, the distance between the electrodes is not to be changed even if a conductive bonding agent 5 runs into the gap between a pin 6 and an element 3 so that the connection may be facilitated to increase the bond strength thereby enabling the electric characteristics to be stabilized.

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 resistance having capacitor characteristics and varistor characteristics for protecting semiconductors and circuits of equipment from abnormal high voltage, noise, static electricity, etc. generated in electric equipment and electronic equipment. 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 preventing static electricity in various electric and electronic devices.
Varistors and ZnO-based varistor are used.
The voltage-current characteristic of such a varistor can be approximately represented 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 index.

The α of SiC varistor is 2 to 7, and the α of some ZnO varistor reaches 50. Although such a varistor has excellent performance in absorbing a relatively high voltage, it has almost no effect in absorbing a relatively low voltage below the varistor voltage due to its low dielectric constant and small intrinsic capacitance. Is not shown, and the dielectric loss tan δ is as large as 5 to 10%.

On the other hand, for removing these low voltage noises, the apparent dielectric constant is about 5 × 10 ⁴ , and tan δ is 1.
% 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 electrostatic capacity is reduced or destroyed, and the semiconductor capacitor does not function as a capacitor.

Therefore, recently, a material containing SrTiO ₃ as a main component and having both characteristics of varistor characteristics and capacitor characteristics was developed, and protection of electronic elements such as IC and LSI in electronic equipment such as computers and circuits and electronic It is used to remove noise that enters from cables and connectors that connect devices to each other.

A conventional voltage-dependent non-resistive porcelain element having characteristics of both a varistor and a capacitor containing SrTiO ₃ as a main component will be described below.

As shown in FIG. 3, the voltage-dependent non-resistive ceramic element 10 used for removing noise that enters from a connector is a semiconductor ceramic containing SrTiO ₃ as a main component and having voltage-dependent nonlinear resistance characteristics. An electrode 12 and an electrode 13 are arranged on the upper and lower surfaces of a cylindrical element 11 made of.

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

[0011]

As described above, in the conventional structure, the conductive adhesive 16 is provided in the gap between the pin 15 and the element 11.
There is a problem in that a part of the liquid crystal flows in, the apparent distance between the electrodes becomes small, the varistor voltage becomes low, the varistor voltage becomes polar, and the insulation resistance becomes low.

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 has no polarity. An object of the present invention is to provide a voltage-dependent nonlinear resistor ceramic element whose insulation resistance does not change.

[0013]

In order to achieve this object, a voltage-dependent nonlinear resistor porcelain element of the present invention comprises a cylindrical through hole at the center and two cylinders having different outer diameters coaxially. An electrode is provided on the entire inner circumference of the through hole in a semiconductor ceramic having a plane of a boundary between the two cylinders, and a length of a cylinder of a large diameter is shorter than a length of a cylinder of a small diameter, Another electrode is arranged on the entire outer circumference of the small-diameter cylinder.

[0014]

In this structure, since the cylindrical inner peripheral electrode is integrated as one electrode, the distance between the electrodes does not change even if the conductive adhesive flows into the gap between the pin and the element, and the common terminal Since the connection is easy, the adhesive force is increased, and the dripping of the extra conductive adhesive is stopped by the cylinder having a large diameter, the distance between the electrodes does not change.

[0015]

【Example】

(Embodiment 1) A first embodiment of the present invention will be described below.

SrCO ₃ , CaCO ₃ , BaCO ₃ , Mg
CO ₃ and TiO ₂ are weighed with various composition ratios changed as shown in (Table 1) and mixed for 24 hours with a ball mill or the like. 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 then dried to obtain the first component.

[0017]

[Table 1]

Next, the first component, the second component and the third component were weighed so as to have the composition ratio shown in (Table 1) below, mixed for 24 hours with a ball mill or the like and then dried to obtain polyvinyl alcohol. After adding 10% by weight of an organic binder such as, for example, and granulating with a press pressure of 1 (t / cm ² ), the outer diameter of the cylinder is 4 mmφ, the inner diameter is 1.4 mmφ, and the height is 2.5 mm. A portion of the cylinder having a large outer diameter 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 such as N ₂ : H ₂ = 9: 1 gas.

After that, baking 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, for example, a method such as roller transfer, and the 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 arranged by a method such as roller transfer. Thereafter, it 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.
It is dried at 0 ° C. for 10 minutes and baked at 630 ° C. for 3 minutes to form 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.

Next, as shown in FIG. 2, the pins 6 and the common terminal 9 are attached by 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 arranged on the inner peripheral surface of an element obtained in the same manner as in the first embodiment by, for example, a roller transfer method or the like, and the outer diameter of the cylinder is set. A conductive ohmic paste made of Zn or the like is provided on the entire outer peripheral surface of the small portion by, for example, a method such as roller transfer, followed by drying at 120 ° C. for 10 minutes and firing at 630 ° C. for 3 minutes. Next, a conductive portion is activated with a weak acid or the like, Cu plating and Ni plating are applied only to the activated portion without electrolysis, and electrolytic solder plating is further applied to the electrode to form an electrode 1 and an electrode 2 having a three-layer structure. To do. Next, similarly to the first embodiment shown in FIG. 2, the pins 6 and the common terminal 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 voltage-dependent resistor porcelain element obtained as described above and after assembly of the connector are shown in (Table 2) and (Table 3), respectively.

[0022]

[Table 2]

[0023]

[Table 3]

V _{1mA in} (Table 2) and (Table 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 these (Table 2) and (Table 3), the voltage-dependent nonlinear resistor ceramic element according to this example is superior to the conventional example in terms of V _{1 mA} polarity and insulation resistance. Is obtained.

Further, a part of Sr of the first component is Ca, Ba,
Although only a part of the ratio of substitution with Mg is shown in the examples, any ratio may be used as long as it is within the range of having both varistor characteristics and capacitor characteristics as the element characteristics. Further, the second component and the third component are shown only for some combinations in the embodiments, but any component may be used as long as it is within the range of simultaneously having varistor characteristics and capacitor characteristics as element characteristics. Further, as the ohmic electrode, there are Ag, Cu, Ni, etc. in addition to Zn, but any other material may be used as long as ohmic connection can be made at the interface between the element and the electrode. The plating method may be electrolytic or electroless, and may be acidic plating, basic plating or neutral plating. Further, although only a part of the combination of plating is shown in the present embodiment, 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 with an inductance such as a ferrite, a coil, or a toroidal coil.

As described above, according to this embodiment, the entire cylinder is formed, one end of the cylinder is made larger in diameter than the other portion, and the larger diameter cylinder is smaller in length. Is shorter than the length of the cylinder, and is formed so as to have a cylindrical through hole at the center of the entire cylinder, and the electrode 1 is arranged 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 it 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.

Further, when the common terminal 9 is connected to the electrode 2 with a conductive adhesive 8 such as solder, the connection is easy and the adhesive force can be increased, and the excess of the conductive adhesive 8 such as extra solder is sagging. The apparent distance between the electrodes can be prevented from changing by stopping at the cylindrical portion of.
In addition, a conductive adhesive 8 such as solder is attached to the outer periphery of the large diameter cylinder.
Even if it falls, the apparent distance between the electrodes does not change because it falls away from the electrode 1. Also, because the entire cylinder is one and one end of the cylinder has a diameter larger than the other part, the surface insulation distance can be wide, so the electrical characteristics are stable, the varistor voltage does not change, and the varistor voltage does not change. The voltage does not have polarity, the insulation resistance does not change, and even if the element is assembled into the connector, the change in characteristics before and after assembly is extremely small and stable, and it is possible to improve the life span. The reliability can be improved. If the gap between the pin 6 and the electrode 1 and the gap between the electrode 2 and the common terminal 9 are made small by solder plating the uppermost layers of the electrode 1, the electrode 2, and the common terminal 9, the conductive adhesive 5 , Electrode 8 only by heat treatment without 8,
The electrodes 2 and the solder plating on the uppermost layer of the common terminal 9 can be melted and connected to each other. In order to bring out the electrical characteristics of the element 3 sufficiently, Cu plating, Ni plating, C
r plating, Sn plating, Pb plating, Au plating, Ag
By using an electrode in which one or more kinds of plating, Pd 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. It can be easily attached, and the solder heat resistance can be improved by using a plurality of types of multilayer plating structures.

Further, although the length of the element is increased by making the element cylindrical, the size of the element can be reduced in the radial direction, so that the pin interval of the connector can be reduced and the connector can be miniaturized. It is effective in converting. Further, by connecting the common terminal 9 to the electrode in the intermediate portion of the element 3, the height protruding from the common terminal 9 can be reduced, and the size can be reduced in the height direction.

[0029]

As is apparent from the above description of the embodiments, the present invention provides two cylinders having different outer diameters coaxially with a cylindrical through hole in the center and a plane of a boundary between the two cylinders. In addition, a large diameter cylinder has a length shorter than that of a small diameter cylinder, and an electrode is provided on the entire inner circumference of the through hole of the semiconductor ceramic having a shape shorter than that of the small diameter cylinder. Even if a part of the conductive adhesive flows into the gap between the pin and the element, the varistor voltage does not change, the varistor voltage does not have polarity, and the insulation resistance does not change. It is possible to realize a voltage-dependent nonlinear resistor ceramic element.

[Brief description of drawings]

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

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

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

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

[Explanation of symbols]

 1 electrode 2 electrode 3 element

Claims (6)

[Claims] 1. A cylinder having a cylindrical through hole at the center thereof, two cylinders having different outer diameters on the same axis and a plane of a boundary between the two cylinders, and a length of the cylinder having a larger diameter. A semiconductor ceramic having a voltage-dependent nonlinear resistance characteristic whose main component is SrTiO _{3 and} having a shape shorter than the length of the smaller diameter, and an electrode provided on the entire inner circumference of the through hole of the semiconductor ceramic. A voltage-dependent nonlinear resistor porcelain element provided with another electrode arranged on the entire outer circumference of the small-diameter cylinder. 2. The voltage-dependent nonlinear resistor porcelain element according to claim 1, wherein the electrode has a structure in which an underlying layer of the ohmic electrode is overlaid with an upper layer of the non-ohmic electrode. 3. The electrode is one or more of Cu plating, Ni plating, Cr plating, Sn plating, Pb plating, Au plating, Ag plating, Pu plating, and solder plating on the base of the ohmic electrode. The voltage-dependent nonlinear resistor ceramic element according to claim 1, wherein the voltage-dependent nonlinear resistor porcelain element has a structure in which grounds are stacked. 4. The electrode has a structure in which one or more kinds of Cu plating, Ni plating, Cr plating, Sn plating, Pb plating, Au plating, Ag plating, Pu plating, and solder plating are stacked. 1. The voltage-dependent nonlinear resistor porcelain element according to 1. 5. The voltage-dependent nonlinear resistor porcelain element according to claim 1, wherein the electrode has a structure in which the uppermost layer is plated with solder. 6. A semiconductor ceramic having voltage-dependent nonlinear resistance characteristics, wherein a part of Sr of the main component SrTiO ₃ is replaced with at least one element of Ca, Ba and Mg. , Claim 2, claim 3, claim 4
Alternatively, the voltage-dependent nonlinear resistor porcelain element according to claim 5.