JP2871060B2 - Voltage-dependent nonlinear resistor porcelain element - Google Patents

Description

The present invention relates to an electric device, an abnormal high voltage generated in an electronic device,
The present invention relates to a voltage-dependent nonlinear resistor porcelain element having capacitor characteristics and varistor characteristics for protecting semiconductors and circuits of equipment from noise, static electricity, and the like.

2. Description of the Related Art Conventionally, SiC varistors having a voltage-dependent nonlinear resistance characteristic for absorbing abnormally high voltage, eliminating noise, eliminating sparks, and preventing static electricity in various electric and electronic devices, and ZnO.
System varistors are used. The voltage-current characteristics of such a varistor can be approximately expressed by the following equation.

I = (V / C) ^α where I is a current, V is a voltage, C is a constant specific to a varistor, and α is a voltage-current nonlinear exponent.

Α of the SiC varistor is about 2 to 7, and α of the ZnO varistor.
There are as many as 50. Such varistors have excellent performance in absorbing relatively high voltages, but because of their low dielectric constant and small inherent capacitance, they are almost insensitive to absorbing relatively low voltages below the varistor voltage. No effect is exhibited, 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 for removing these low-voltage noises and the like. However, 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, and the function as a capacitor is not fulfilled.

Therefore, recently, a device having SrTiO ₃ as a main component and having both functions of a varistor characteristic and a capacitor characteristic has been developed, and ICs and LSIs in electronic devices such as computers are used to protect any semiconductor elements and circuits and to interconnect electronic devices. It is used to remove noise that intrudes from cables and connectors that connect to the computer.

Problems to be Solved by the Invention When the above-described element having both functions of a varistor and a capacitor mainly composed of SrTiO ₃ is used for removing noise invading from a connector or the like, the structure of the element is generally the third.
It looks like the figure. In FIG. 3, reference numerals 11 and 12 denote electrodes, and reference numeral 13 denotes an element made of a semiconductor ceramic having SrTiO ₃ as a main component and having a voltage-dependent nonlinear resistance characteristic. When such an element is incorporated in a connector, it is generally as shown in FIG. However, with the configuration as shown in FIG. 4, part of the solder 15 flows into the gap between the pin 14 and the element 18, the apparent distance between the electrodes is reduced, the varistor voltage is reduced, and the varistor voltage is polarized. There was a disadvantage that the insulation resistance was low. In FIG. 4, 16 and 17 are electrodes, 19 is solder, and 20 is a common terminal.

In view of the above, an object of the present invention is to provide an element having a configuration in which the varistor voltage does not change even if a 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. Things.

Means for Solving the Problems In order to achieve this object, a voltage-dependent nonlinear resistor porcelain element of the present invention has a cylindrical shape having a through hole in the center.
A semiconductor ceramic containing SrTiO ₃ as a main component, and a donut-shaped electrode provided on both end surfaces of the semiconductor ceramic such that the outer circumference is smaller than the outer diameter of the semiconductor ceramic and the inner circumference has the same diameter as the through hole. An electrode provided on the inner peripheral surface of the through-hole so as to be integrated with the donut-shaped electrode; and an electrode provided at the center of the outer peripheral surface of the semiconductor ceramic at equal intervals from both end surfaces of the semiconductor ceramic. And an electrode.

Operation According to this configuration, since the electrodes provided on both end surfaces and the inner peripheral surface are integrated, when this voltage-dependent non-linear resistor porcelain element is incorporated into a connector or the like by soldering or the like, the voltage-dependent nonlinear resistor porcelain element is inserted into the through hole. Even if a part of the solder flows, the apparent distance between the electrodes does not change because it is present on the electrodes. Accordingly, the varistor voltage does not change, the polarity does not change, and the insulation resistance does not change. Therefore, the change in the electrical characteristics before and after the incorporation is extremely small and stable.

The electrodes provided on both end surfaces of the semiconductor ceramic have an outer diameter smaller than the outer diameter of the semiconductor ceramic, and the electrodes provided at the center of the outer peripheral surface are formed at equal intervals from both end surfaces of the semiconductor ceramic. As a result, the surface insulation distance between the electrodes is increased, and the service life characteristics can be improved, thereby improving the reliability.

Furthermore, when a terminal is connected to an electrode provided at the center of the outer peripheral surface of the semiconductor ceramic, soldering can be performed on the entire surface of the connection end of the terminal with this electrode, so that the terminal and the voltage-dependent nonlinear resistor ceramic element can be connected to each other. The bonding strength is improved and the reliability is improved.For example, when the connector is incorporated in a connector, the height of the upper part of the terminal is about half that of the voltage-dependent nonlinear resistor porcelain element because the terminal is located at the center, and the low Can be tall.

Furthermore, since the voltage-dependent nonlinear resistor porcelain element of the present invention has a symmetric structure in front, rear, left and right, it has no directionality, and when assembled into a connector or the like, it is not necessary to determine front, rear, left, and right. Can be reduced.

Examples Hereinafter, the present invention will be described specifically with reference to examples. First, SrCO ₃ , CaCO ₃ , BaCO ₃ , MgCO ₃ , and TiO ₂ were weighed at various composition ratios as shown in Table 1 below, and were weighed using a ball mill or the like.
Mix for 24 hours. 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 then 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 below, mixed for 24 hours by a ball mill or the like, dried, and dried with an organic binder such as polyvinyl alcohol by 10 wt. % And granulated after adding 1% (t / cm ² ) with a pressing pressure of 1 (t / cm ² )
mφ, 2.5mm t height, and molded at 1100 ℃ in air
Bake for 12 hours and remove binder. Next, a reducing atmosphere,
For example, firing is performed at 1450 ° C. for 3 hours in a gas of N ₂ : H ₂ = 9: 1. After that, 6H at 1020 ° C in an oxidizing atmosphere such as air
r Bake.

Using a conductive paste such as Ag on both end surfaces of the thus obtained sintered body, a donut-shaped electrode having an outer periphery smaller than the outer diameter of the cylinder and an inner periphery having the same diameter as the through hole is formed by, for example, screen printing. At the same time, an electrode is provided on the inner peripheral surface of the through hole by, for example, a roller transfer method, and the donut-shaped electrode and the electrode on the inner peripheral surface of the through hole are integrated. Further, electrodes facing each other are provided on the outer peripheral surface at the center of the cylinder at equal intervals from the end surface by, for example, a roller transfer method, and are fired at 630 ° C. for 3 minutes to form electrodes. FIG. 1 shows an element obtained in this way, 1 is an electrode provided integrally from the inner peripheral surface of the cylinder to both end surfaces, and 2 is provided on the outer peripheral surface at the center of the cylinder. The electrodes 3 are elements made of a semiconductor ceramic having SrTiO ₃ as a main component and having a voltage-dependent nonlinear resistance characteristic, and a cylindrical through-hole is formed at the center of the cylinder. Next, as shown in FIG. 2, the pins 4 and the common terminal 10 are attached by solder 5, solder 9, and the like, and are filled with a resin (not shown) such as butadiene rubber. In FIG. 2, 6
And 7 are electrodes, and 8 is an element. The characteristics of the element thus obtained are shown in Table 2 below for the element alone and after assembling the connector.

Note that _V1mA is the voltage applied across the element when a current of 1mA flows, and the polarity of _V1mA is V1mA in the positive direction and _V1mA in the negative direction.
A value obtained by dividing the difference between V _1mA in the positive direction of V _1mA, the insulation resistance is the insulation resistance between the pin 4 and the common terminal 10 when the applied voltage 12V.DC.

Although the ratio of replacing part of Sr of the first component with Ca, Ba, and Mg is only partially shown in the embodiment, any ratio within a range having both varistor characteristics and capacitor characteristics as element characteristics at the same time is shown. It may be something like this. Further, although the second component and the third component are shown only for some combinations in the embodiment, any components may be used as long as the varistor characteristic and the capacitor characteristic are simultaneously included in the element characteristics. . In addition, the voltage-dependent nonlinear resistor porcelain element is connected to an inductance composed of, for example, a ferrite, a coil, a toroidal coil, etc., so that the noise removing effect can be improved.

Effect of the Invention According to the present invention, since the electrodes provided on both end surfaces and the inner peripheral surface are integrated, when this voltage-dependent nonlinear resistor porcelain element is incorporated into a connector or the like by soldering or the like, the Even if a part of the solder in the hole flows, the apparent distance between the electrodes does not change because it exists on the electrodes. Accordingly, the varistor voltage does not change, the polarity does not change, and the insulation resistance does not change. Therefore, the change in the electrical characteristics before and after the incorporation is extremely small and stable.

The electrodes provided on both end surfaces of the semiconductor ceramic have an outer diameter smaller than the outer diameter of the semiconductor ceramic, and the electrodes provided at the center of the outer peripheral surface are formed at equal intervals from both end surfaces of the semiconductor ceramic. As a result, the surface insulation distance between the electrodes is increased, and the service life characteristics can be improved, thereby improving the reliability.

Furthermore, when a terminal is connected to an electrode provided at the center of the outer peripheral surface of the semiconductor ceramic, soldering can be performed on the entire surface of the connection end of the terminal with this electrode, so that the terminal and the voltage-dependent nonlinear resistor ceramic element can be connected to each other. The bonding strength is improved and the reliability is improved.For example, when the connector is incorporated in a connector, the height of the upper part of the terminal is about half that of the voltage-dependent nonlinear resistor porcelain element because the terminal is located at the center, and the low Can be tall.

Furthermore, the voltage-dependent non-inductive resistor porcelain element of the present invention has a symmetric structure in front, rear, left and right, so it has no directionality, and when assembled into a connector or the like, it is unnecessary to determine front, rear, left and right, and the number of assembly steps is reduced. Can be reduced.

[Brief description of the drawings]

FIG. 1 is a sectional view showing an element according to the present invention, FIG. 2 is a sectional view when the element according to the present invention is assembled into a connector, and FIG.
FIG. 4 is a cross-sectional view showing an element according to a conventional example, and FIG. 4 is a cross-sectional view when the element according to the conventional example is assembled into a connector. 1,2,6,7 ... electrode, 3,8 ... element, 4 ... pin, 5,9 ...
Solder, 10 common terminal.

Claims (2)

(57) [Claims] 1. A cylindrical SrTiO ₃ having a through hole in the center.
And a doughnut-shaped electrode provided on both end surfaces of the semiconductor ceramic such that the outer circumference is smaller than the outer diameter of the semiconductor ceramic and the inner circumference has the same diameter as the through hole. An electrode provided on the inner peripheral surface of the through hole so as to be integrated with the donut-shaped electrode,
A voltage-dependent non-linear resistor porcelain element, comprising: an electrode provided at the center of the outer peripheral surface of the semiconductor ceramic at an equal distance from both end surfaces of the semiconductor ceramic. 2. 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.