JPH0442503A - Voltage dependent nonlinear resistance procelain element - Google Patents

Abstract

PURPOSE:To obtain a low-price element having a superior solder-heat resistance in which a varistor voltage does not change and also an insulating resistance does not change by a method wherein a doughut-form electrode of a main conductor ceramic cylinder is united into one body with an electrode of an inner circumferential plane and overlaying a non-ohmic electrode on an ohmic electrode as a fundamental one. CONSTITUTION:On one end plane of a sintered body, a doughnut-form electrode is formed by using an ohmic electrode of Ag, for example, as a fundamental one and also an ohmic electrode is formed on an inner circumferential plane and these are united into one body, thereby forming a fundamental elementrode 1. Meanwhile, on another end plane, a counter ohmic electrode is arranged on an outer circumferential plane so as to form a fundamental electrode 3. Next, upper electrodes 2, 4 consisting of non-ohmic electrodes are formed by using a non-ohmic paste such as Ag as a upper coating. These are sintered to make an element 5.

Description

DETAILED DESCRIPTION OF THE INVENTION Field of Industrial Application The present invention relates to a voltage having capacitor characteristics and varistor characteristics to protect semiconductors and circuits of equipment from abnormal high voltage, noise, static electricity, etc. generated in electrical equipment and electronic equipment. This invention relates to dependent nonlinear resistance ceramic elements.

Conventional technology Conventionally, SiC varistors and Z
nO type varistors are used. The voltage-current characteristics of such a varistor can be approximately expressed as in the following equation.

I=(V/C)" Here, ■ is current, ■ is voltage, C is a constant specific to the varistor, and α is a voltage-current nonlinear index.

The α of SiC varistors is about 2 to 7, and the α of some ZnO-based varistors is as high as 50. Such varistors have excellent performance in absorbing relatively high voltages, or have a low dielectric constant and small inherent capacitance, making them almost ineffective in absorbing relatively low voltages below the varistor voltage. Furthermore, the dielectric loss tan δ is as large as 5 to 10%.

On the other hand, semiconductor capacitors with an apparent dielectric constant of about 5 x 10' and a tan δ of about 1% are used to remove these low voltage noises.

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 decreases or is destroyed, and the capacitor no longer functions as a capacitor.

Recently, products containing 5rTi03 as the main component and having both varistor and capacitor properties have been developed, and ICs and L
It is used to protect semiconductor elements and circuits such as SI, and to remove noise that enters from cables and connectors that interconnect electronic devices.

Problems to be Solved by the Invention When an element having the functions of both a varistor and a capacitor, which is mainly composed of 5rTi03, is used to remove noise that enters from a connector etc., the configuration of the element is generally a third type. It looks like the picture. In FIG. 3, 15 and 16 are electrodes, and 17 is an element.

When such an element is incorporated into a connector, it generally becomes as shown in FIG. However, when the configuration shown in Fig. 4 is used, a portion of the solder 19 flows into the gap between the pin 18 and the element 22, and the distance between the upper electrodes appears to become smaller, lowering the varistor voltage and causing polarity in the varistor voltage. It has the drawbacks of being thick and having low insulation resistance. In FIG. 4, 20 and 21 are electrodes, 19 is solder, and 24 is a common terminal.

Therefore, in the present invention, even if a part of the solder 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. The purpose is to provide an inexpensive element that is easy to attach and has excellent soldering heat resistance.

Means for Solving the Problems In order to solve the above problems, in the present invention, SrTiO
A semiconductor ceramic having a voltage-dependent non-linear resistance characteristic mainly composed of 3 is formed so as to have a cylindrical through hole in the center of the cylinder, and one end surface of the cylinder has an outer periphery smaller than the outer diameter of the cylinder. A donut-shaped electrode with a smaller inner circumference or the same diameter as the through-hole is provided, and an electrode is provided on the inner circumferential surface of the through-hole, and the donut-shaped electrode and the electrode on the inner circumferential surface of the through-hole are integrated. , Opposing electrodes are provided on the outer peripheral surface of the cylinder on the other end surface side of the cylinder, and the electrodes used for these are characterized in that the base is an ohmic electrode and the upper layer is stacked with a non-ohmic electrode. The present invention attempts to solve this problem by obtaining a voltage-dependent nonlinear resistance ceramic element.

According to the configuration of the present invention, a donut-shaped electrode is provided on one end surface of the cylinder, and the outer circumference is smaller than the outer diameter of the cylinder and the inner circumference has the same diameter as the through hole. An electrode is provided on the circumferential surface, the donut-shaped electrode and the electrode on the inner circumferential surface of the through hole are integrated, and an opposing electrode is provided on the outer circumferential surface of the cylinder on the other end surface side of the cylinder. As a result, one end surface of the cylinder and the inner peripheral surface of the through hole are integrated as one electrode, so even if some solder flows into the gap between the pin and the element when it is assembled into a connector, it will not be integrated. The distance between the electrodes does not appear to change because the distance between the electrodes is above the top electrodes.

Therefore, the electrical characteristics are stable and the varistor voltage does not change.
The varistor voltage has no polarity, and the insulation resistance does not change. In addition, in order to fully bring out the characteristics of the element, the electrodes are constructed with an ohmic electrode as the base layer and a non-ohmic electrode on the upper layer, thereby eliminating the formation of a barrier at the interface between the element and the electrode. This means that the characteristics can be fully brought out, it can be easily soldered, and the soldering heat resistance can be improved.

Example The present invention will be specifically described below with reference to Examples.

First, 5rCO:+, CaC0:+, BaCOzMgC
O3 and TiO: are weighed at various composition ratios as shown in Table 1 below, and mixed for 22 hours using a ball mill or the like. Next, after drying it, it was calcined at 1120°C for 4 hours, ground again for 22 hours using a ball mill, etc., and then dried.
Let it be the first component.

Next, the first component, second component, and third component were weighed to have the composition ratio shown in Table 1 below, mixed for 22 hours using a ball mill, etc., dried, and an organic binder such as polyvinyl alcohol was added to 1Qwt. After adding % and granulation,
1 (t/crt) press pressure, outer diameter 4φ, inner diameter 1
, 4φ, height 2.5t (mm), and baked in air at 1110° C. for 11 hours to remove the binder. Next, baking is performed at 1420° C. for 5 hours in a reducing atmosphere, for example, a gas of N2:H2=9:1. Furthermore, after that
Sintering is performed at 1050° C. for 5 hours in an oxidizing atmosphere such as air.

On one end surface of the sintered body thus obtained, A was applied as a base layer.
Using an ohmic electrode such as g, a donut-shaped electrode having an outer circumference smaller than the outer diameter of the cylinder and an inner circumference having the same diameter as the through hole is provided by, for example, screen printing, and on the inner circumferential surface of the through hole. An ohmic electrode is provided by a method such as roller transfer, and the donut-shaped electrode and the electrode on the inner peripheral surface of the forward bending through hole are integrated to form a base electrode 1 as shown in FIG. dry. Furthermore, opposing ohmic electrodes are provided on the outer peripheral surface of the cylinder on the other end surface side of the cylinder by a method such as roller transfer, thereby forming the base electrode 3 and drying at 100°C. Next, upper electrodes 2 and 4 made of non-ohmic electrodes are formed using a non-ohmic paste such as Ag as the upper layer in the same manner as the ohmic electrode is formed on the ohmic electrode. Fire at 585° C. and 7 ml. In this way, the element 5 is manufactured.

When incorporating the element 5 into a connector, solder 7. as shown in FIG. Solder 13 and pin 6
and the common terminal 14 are attached, and the base electrodes 8 and 10 and the upper base electrode 9 are made of resin such as phthalene rubber (not shown).
The periphery of the element 12 provided with 11 is molded. The characteristics of the element thus obtained are shown in Table 2 below for the element alone and after assembly of the connector.

In Table 2, Vlm, A is the voltage applied to both ends of the element when a current of 1 mA flows, and the polarity of Vl,, nA is the difference between VlmA in the positive direction and Vl in the negative direction. , nA, and the insulation resistance is the applied voltage 1
This is the insulation resistance value between pin 6 and common terminal 14 at 2V, D, and C.

(Margin below) Here, the ratio of replacing a part of Sr in the first component with Ca and BaMg is only partially shown in the example, or is within the range where the element has both varistor and capacitor characteristics. It doesn't matter if it's something like.

Furthermore, although only some combinations of the second and third components are shown in the embodiments, they may be any other component as long as the device has varistor characteristics and capacitor characteristics at the same time. In addition to Ag, Zn and Cu can be used as omic electrodes.

Examples include Ni, but any material other than these may be used as long as it can establish an ohmic connection with the element. Further, the upper electrode may be any non-ohmic electrode that can be soldered and has excellent solder heat resistance. Furthermore, the noise removal effect can be improved by connecting an inductance made of, for example, ferrite or a toroidal coil to the voltage-dependent nonlinear resistance ceramic element.

Effects of the Invention As described above, according to the present invention, a donut-shaped electrode is provided on one end surface of the cylinder, and the outer circumference is smaller than the outer diameter of the cylinder and the inner circumference has the same diameter as the through hole. An electrode is provided on the inner circumferential surface of the through hole, the donut-shaped electrode and the electrode on the inner circumferential surface of the through hole are integrated, and opposing electrodes are provided on the outer circumferential surface of the cylinder on the other end surface side of the cylinder. With this configuration, one end surface of the cylinder and the inner circumferential surface of the through hole are integrated as one electrode.
Even if some of the solder flows into the gap between the bottle and the element when it is assembled into a connector or the like, the apparent distance between the upper electrodes does not change because it is on the integrated electrode. Therefore, the electrical characteristics are stable, the varistor voltage does not change, the varistor voltage has no polarity, the insulation resistance does not change, and even when the element is assembled into a connector, the change in characteristics before and after assembly is extremely small and stable. Effects can be obtained. In addition, by making the element cylindrical, the length of the element becomes longer, but the element can be made smaller in the radial direction, which makes it possible to reduce the interval between the bins of the connector, making the connector more compact. It is effective for Furthermore, in order to fully bring out the characteristics of the element, the electrodes are constructed by layering an ohmic electrode on the base layer and a non-ohmic electrode on the top layer.
It is possible to fully bring out the characteristics of the element without forming a barrier at the interface between the element and the electrode, and it is possible to easily solder and improve the soldering heat resistance of the electrode.

[Brief explanation of the drawing]

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 invention is assembled into a connector, and Fig. 3 is a sectional view showing an element according to the present invention.
The figure is a sectional view showing a conventional element, and FIG. 4 is a sectional view of the conventional element assembled into a connector. 1.3, 8.10... Base electrode, 2, 4, 91
1... Upper electrode, 5, 12... Element according to the present invention, 6... Bin, 7.13...
・Handa, 14.・1.・, common terminal. Name of agent: Patent attorney Takuhei Awano and one other person Figure 1 Figure 2 Binni = Go] / 14 Figure t /l shoes 16 Funeral map μz3 = = Mado 24

Claims (2)

[Claims] (1) A semiconductor ceramic mainly composed of SrTiO_3 and having voltage-dependent non-linear resistance characteristics is formed to have a cylindrical through hole in the center of the cylinder, and the outer periphery of the cylinder is formed on one end surface of the cylinder. A donut-shaped electrode smaller than the outer diameter and having an inner circumference the same diameter as the through-hole is provided, and an electrode is provided on the inner circumferential surface of the through-hole, and the donut-shaped electrode and the electrode on the inner circumferential surface of the through-hole are provided. are integrated, and opposing electrodes are provided on the outer peripheral surface of the cylinder on the other end surface side of the cylinder, and the electrodes used for these are ohmic electrodes on the base and non-ohmic electrodes on the top. Features a voltage-dependent nonlinear resistance ceramic element. (2) The voltage-dependent nonlinear resistance ceramic element according to claim 1, wherein a part of the main component Sr is replaced with at least one element selected from Ca, Ba, and Mg.