JPH05109507A - Voltage dependent non linear resistor porcelain device - Google Patents

Abstract

PURPOSE:To obtain a device which attaches no polarity to varistor voltage and produces no changes in insulation resistance by forming semiconductor ceramics in cylindrical shape and, what is more, defining the cylindrical shape of the semiconductor device in such a fashion that one terminal section of the cylinder may be larger-sized than the other terminal section. CONSTITUTION:A cylindrical shape 13 is formed with semiconductor ceramics mainly composed of SrTiO2 and having voltage dependent non linear resistant characteristics. One terminal section 10 of the cylinder 13 is larger-sized than the other terminal section 9 and formed in cylindrical shape as well. The length of the larger-sized cylinder 10 is made shorter than that of the other portion 9. In the central part of the cylinder 13 is formed a penetration hole. An inner peripheral electrode 11 is formed on the whole inner peripheral surface of the cylinder 13, thereby forming an outer peripheral electrode 12 on the whole outer peripheral surface of the small-sized portion of the cylinder 13 and on a doughnut-shaped plane in contact with the small-sized cylindrical portion 9 on the larger-sized cylinder 10. It is also acceptable to replace a part of main component Sr of the semiconductor ceramics with one element and more, such as Ca, Ba and Mg. This construction makes it possible to stabilize the electric properties and obtain high reliability devices as well.

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. The present invention 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 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.

Α of a SiC varistor is about 2 to 7, ZnO
In some system varistor, α is as high as 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, a semiconductor capacitor having an apparent dielectric constant of about 5 × 10 ⁴ and a Tan δ of about 1% is used to remove these low-voltage noises. However, when a voltage or current exceeding a certain limit is applied due to a surge or the like, the capacitance of such a semiconductor capacitor 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 functions of both varistor characteristics and capacitor characteristics has been developed, and protection of semiconductor elements and circuits such as IC and LSI in electronic devices 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.

[0008]

DISCLOSURE OF THE INVENTION Problems to be Solved by the Invention₃The Lord
Functions as both a varistor and a capacitor as components
Used to remove the noise that enters the element from the connector etc.
In general, the element structure is as shown in Fig. 3.
It In FIG. 3, 1 and 2 are electrodes and 3 is SrTiO 3. ₃To
A semiconductor having voltage-dependent nonlinear resistance characteristics as a main component
An element made of ceramic. Connect an element like this
When assembled in the actuator, it is generally as shown in FIG. However
With the configuration shown in Fig. 4, the gap between pin 4 and element 3
A part of the field 5 flows in and the apparent distance between the electrodes becomes small.
Therefore, the varistor voltage becomes low and the varistor voltage has polarity.
It had the drawback of low insulation resistance. Figure 4
, 6 is solder as a conductive connecting member, 7 is common
It is a terminal.

Therefore, it is an object of the present invention to provide an element having a structure in which the varistor voltage does not change even if part of the solder flows into the gap between the pin and the element, the varistor voltage does not have polarity, and the insulation resistance does not change. To do.

[0010]

In order to achieve the above object, according to the present invention, a semiconductor ceramic having SrTiO ₃ as a main component and having a voltage-dependent nonlinear resistance characteristic is entirely cylindrical and one of The end portion is formed into a cylindrical shape having a diameter larger than that of the other portion, and the length of the large diameter cylinder is shorter than that of the other portion so that the central portion of the entire cylinder has a cylindrical through hole. And while providing one electrode on the entire inner peripheral surface of the cylinder, in a donut-shaped plane in contact with the entire outer peripheral surface of the portion of the outer diameter of the cylinder is small and the cylindrical portion of the outer diameter of the cylinder of the large diameter cylinder is small. The other electrode is provided.

[0011]

According to the present invention, since the inner electrode of the cylinder is integrated as one electrode, even if solder or a conductive adhesive flows into the gap between the pin and the element, it is on the integrated electrode. Therefore, the apparent distance between the electrodes does not change. Therefore, the electrical characteristics are stable, the varistor voltage does not change, the varistor voltage does not have polarity, and the insulation resistance does not change.

Further, by providing the other electrode over the entire portion of the cylinder having a small outer diameter, when the outer electrode is connected to the common terminal with solder or a conductive adhesive, the connection is easy and the adhesive strength is large. The apparent inter-electrode distance does not change by stopping the sagging of excess solder or conductive adhesive with a cylindrical part with a cylindrical shape whose one end is larger than the other part. You can Further, even if the conductive adhesive such as solder falls down, it falls down in the direction away from the other electrode, so that the apparent distance between the electrodes does not change. Further, by providing the other electrode on the doughnut-shaped flat surface in contact with the cylindrical portion having a small outer diameter of the large diameter cylinder, the contact area becomes large when the common terminal is connected by a conductive adhesive or the like. Connection is easy, and since it can be connected from two directions, the adhesive force between the common terminal and the element can be strengthened, the mechanical strength can be improved, and the deterioration of characteristics due to the temperature cycle test can be reduced. It is possible to improve reliability. If the innermost electrode, the outermost electrode, and the uppermost layer of the common terminal are plated with solder, for example, the gap between the pin and the innermost electrode and the gap between the outermost electrode and the common terminal are reduced, the conductive adhesive member is eliminated. However, the inner peripheral electrode, the outer peripheral electrode, and the solder plating on the uppermost layer of the common terminal can be melted and connected to each other only by heat treatment. Further, in order to sufficiently bring out the electrical characteristics of the element, at least one of Cu plating, Ni plating, Cr plating, Sn plating, Pb plating, Au plating, Ag plating, Pd plating, and solder plating should be stacked. By doing so, the electrical characteristics of the element can be sufficiently drawn out without forming a barrier at the interface between the element and the electrode, and it can be easily soldered. Can be improved.

[0013]

Embodiments (Embodiment 1) Hereinafter, embodiments will be specifically described.

First, SrCO ₃ , CaCO ₃ , BaCO ₃ ,
MgCO ₃ and TiO ₂ are weighed with various composition ratios changed as shown in (Table 1) and (Table 2) below, and mixed for 34 h by a ball mill or the like. Next, after drying, it is heated at 1050 ° C. for 10 minutes.
After baking for h, it is crushed again by a ball mill for 34 h and then dried to obtain the first component.

[0015]

[Table 1]

[0016]

[Table 2]

Next, the first component, the second component, and the third component were weighed so that the composition ratios shown in the following (Table 1) and (Table 2) were obtained, mixed with a ball mill for 34 hours, and then dried. Then, after adding 10 wt% of an organic binder such as polyvinyl alcohol to granulate, the portion with a small outer diameter of the cylinder at a press pressure of 1 (t / cm ² ) has an outer diameter of 4 mm, an inner diameter of 1.4 mm, and a height of 2.5 mm. _t, the outside diameter is larger portion of the cylinder is formed into a cylindrical shape having an outer diameter 6mmφ inner diameter 1.4mmφ height 0.5 mm ^t, to debinder and 15h fired at 1230 ° C. in air. next,
14 in a reducing atmosphere such as N ₂ : H ₂ = 9: 1 gas
Bake for 4 hours at 15 ° C. After that, an oxidizing atmosphere,
For example, it is baked in air at 1135 ° C. for 4 hours. An ohmic conductive paste made of Zn or the like is provided on the inner peripheral surface of the thus obtained sintered body by, for example, a method such as roller transfer, and the entire outer peripheral surface of the portion where the outer peripheral diameter of the cylinder is small is made of Zn or the like. Ohmic conductive paste,
For example, an ohmic conductive paste made of Zn or the like is provided on a donut-shaped flat surface which is provided by a method such as roller transfer and is in contact with a cylindrical portion having a small outer diameter of the cylinder having the large diameter, and a method such as roller transfer is used. To provide the other electrode. After that, 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, dried at 120 ° C. for 10 minutes, and baked at 630 ° C. for 3 minutes. A peripheral electrode and an outer peripheral electrode are formed. FIG. 1 shows an element thus obtained, 11 is an inner peripheral electrode provided on the entire inner peripheral surface of the cylinder, 12 is the entire outer peripheral surface of the portion where the outer peripheral diameter of the cylinder is small and on the large diameter cylinder. An outer peripheral electrode provided on a doughnut-shaped flat surface in contact with the cylindrical portion having a small outer peripheral diameter, and 13 is an element made of a semiconductor ceramic containing SrTiO ₃ as a main component and having voltage-dependent nonlinear resistance characteristics. A cylindrical through hole is formed in the center. Next, as shown in FIG. 2, the pins 16 and the common terminal 17 are attached by the conductive connecting members 14 and 15 such as solder or a conductive adhesive, and a resin such as butadiene rubber is filled and heat-cured. In addition, 18 is a case.

(Example 2) After obtaining a fired body in the same manner as in Example 1, an ohmic conductive paste made of Zn or the like is provided on the inner peripheral surface by, for example, a roller transfer method or the like, Z on the entire outer peripheral surface of the part where the outer diameter is small
An ohmic conductive paste composed of n or the like is provided by, for example, a method such as roller transfer, and further, a ohmic property composed of Zn or the like is formed on a donut-shaped flat surface in contact with a cylindrical portion having a small outer diameter of the cylinder having the large diameter. After the other electrode is provided by, for example, a method such as roller transfer, the conductive paste of (1) 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, and only the portion activated by electroless is Cu-plated-N.
Then, i-plating is performed, and electrolytic solder plating is performed on the i-plating to form a three-layer structure to form the inner peripheral electrode 11 and the outer peripheral electrode 12.
Next, as in Example 1, a conductive connecting member 1 such as solder
The pin 16 and the common terminal 17 are attached with 4, 15, and the like, a resin such as butadiene rubber is filled, and the resin is cured by heating. The characteristics of the element thus obtained are shown in (Table 3) and (Table 4) after assembling the element alone and the connector.

[0020]

[Table 3]

[0021]

[Table 4]

V1mA is a voltage applied to both ends of the element when a current of 1mA is applied, and the polarity of V1mA is a value obtained by dividing the difference between V1mA in the positive direction and V1mA in the negative direction by V1mA in the positive direction. Insulation resistance is pin 1 when applied voltage is 12VDC
6 is an insulation resistance value between 6 and the common terminal 17.

In the above-mentioned embodiments, the ratio of substituting Ca, Ba, and Mg for a part of Sr of the first component is only partially shown in the embodiments, but the varistor characteristics and the capacitor are the characteristics of the element. It does not matter as long as it has the characteristics at the same time. The second component,
Although the third component is shown only for some combinations in the embodiments, any component may be used as long as it is within the range of simultaneously having varistor characteristics and capacitor characteristics as the element characteristics. Zn is used as the ohmic electrode.
Other than these, there are Ag, Cu, Ni and the like, but any other material may be used as long as ohmic contact can be made at the interface between the element and the electrode. Also, only a part of the components to be plated and the combination thereof are shown, but the components and combinations other than these are not limited to these as long as similar effects can be obtained. The plating method may be electrolytic or electroless, acidic plating, basic plating or neutral plating. Further, it is possible to improve the noise removing effect by connecting the voltage-dependent nonlinear resistor porcelain element to an inductance such as a ferrite, a coil, a toroidal coil.

[0024]

As described above, according to the present invention, since the cylindrical inner peripheral electrode is integrated as one electrode, it is integrated even if a conductive connecting member such as solder flows into the gap between the pin and the element. The apparent inter-electrode distance does not change because it is on the separated electrodes.

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. In addition, the other electrode is provided on the entire portion of the cylinder with a small outer diameter, and the other electrode is provided on the doughnut-shaped flat surface in contact with the portion of the large diameter cylinder with a small outer diameter. When connecting with a connecting member, etc., the contact area is large and connection is easy, and since it is possible to connect from the upper and lower sides of the common terminal, it is possible to increase the adhesive force between the common terminal and the element. In addition to improving the mechanical strength, it is possible to reduce the deterioration of the characteristics due to the temperature cycle test and improve the reliability.

Furthermore, by providing the other electrode on the entire portion of the cylinder having a small outer diameter, when the outer electrode is connected to the common terminal by a conductive connecting member such as solder, the connection is easy and the adhesive force can be increased. To prevent the apparent inter-electrode distance from changing by stopping the sagging of excess solder or conductive adhesive at the cylindrical part where the whole is cylindrical and one terminal of the cylinder is larger in diameter than the other part. can do. Even if the solder, the conductive adhesive, or the like drips, the apparent distance between the electrodes does not change because the drips in the direction away from the other electrode.

Moreover, by providing a cylindrical portion having a whole cylindrical shape and one end of the cylinder having a diameter larger than that of the other portion, the surface insulation distance can be widened so that the electrical characteristics are stable and the varistor voltage is small. The varistor voltage does not change, the polarity does not change, the insulation resistance does not change, and even if the element is assembled into the connector, the change in the characteristics before and after assembly is extremely small and stable, and it is possible to improve the life span characteristics. Therefore, the reliability can be improved.

If the uppermost layers of the inner and outer peripheral electrodes and the common terminal are plated with solder, for example, the gap between the pin and the inner peripheral electrode and the gap between the outer peripheral electrode and the common terminal can be made small, the conductive bonding can be achieved. Even if there is no agent, just heat treatment,
The innermost electrode, the outermost electrode, and the solder plating of the uppermost layer of the common terminal can be melted and connected to each other.

Further, in order to sufficiently bring out the electrical characteristics of the element, Cu plating, Ni plating, Cr plating, Sn
By stacking at least one of plating, Pb plating, Au plating, Ag plating, Pd plating, and solder plating, the electric characteristics of the element can be sufficiently improved without forming a barrier at the interface between the element and the electrode. In addition, the solder heat resistance can be improved by adopting a multi-layered plating structure of a plurality of types. 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 for

[Brief description of drawings]

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

FIG. 2 is a cross-sectional view when the same element is assembled into a connector.

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

FIG. 4 is a cross-sectional view when the same element is assembled into a connector.

[Explanation of symbols]

 11 inner peripheral electrode 12 outer peripheral electrode 13 element

Claims (6)

[Claims] 1. A semiconductor ceramic comprising SrTiO ₃ as a main component and having a voltage-dependent nonlinear resistance characteristic, which has a cylindrical shape as a whole, and one end of which has a diameter larger than that of the other portion. A cylinder having a large diameter is formed to have a cylindrical through hole in the central portion of the entire cylinder having a shorter length than other portions, and with one electrode provided on the entire inner peripheral surface of the cylinder, The other electrode is provided on a doughnut-shaped flat surface that is in contact with the entire outer peripheral surface of the portion having a small outer diameter of the cylinder and the cylindrical portion having a small outer diameter of the cylinder of the large diameter cylinder. Linear resistor porcelain element. 2. The electrode is characterized in that the base is an ohmic electrode and the upper layer is a non-ohmic electrode.
The voltage-dependent nonlinear resistor porcelain element described. 3. An electrode is an ohmic electrode as a base, and an upper layer is Cu-plated, Ni-plated, Cr-plated, Sn-plated,
2. The voltage-dependent nonlinear resistor ceramic element according to claim 1, wherein at least one of Pb plating, Au plating, Ag plating, Pd plating, and solder plating is laminated. 4. The electrode is formed by stacking at least one of Cu plating, Ni plating, Cr plating, Sn plating, Pb plating, Au plating, Ag plating, Pd plating, and solder plating. The voltage-dependent nonlinear resistor porcelain element according to claim 1. 5. The voltage-dependent nonlinear resistor porcelain element according to claim 1, wherein the uppermost layer of the electrode is solder plating. 6. The voltage-dependent nonlinear resistor porcelain element according to claim 1, wherein a part of Sr as a main component is replaced with at least one element of Ca, Ba and Mg.