JPH0442502A - Voltage dependent nonlinear resistance porcelain element - Google Patents

Abstract

PURPOSE:To obtain an element which as a good soldering property and a superior resistance to beat in soldering by a method wherein a doughnut-form electrode having the same inner diameter as a through-hole is formed on one end plane of a semiconductor ceramic cylinder is formed and it is united into one body with an electrode of an inner circumferential plane of the hole and counter electrode is arranged on an outer circumferential plane on another end plane side at a distance from the end plane, so that a varistor voltage does not change even if a part of solder flows into a gap between a pin and an element. CONSTITUTION:On one end plane of a cylindrical sintered body composed of SrCo3, CaCo3, BaCO3, MgCO3 and TiO2, a doughnut-form electrode whose diameter is smaller than an outer diameter of a cylinder and whose inner diameter is the same as a through-hole is formed by using a conductive paste, and an electrode is arranged on an inner circumferential plane of the hole and these electrodes are united into one body to from a fundamental elec trode 1. On another end plane side of the cylinder, a counter electrode is arranged to form a fundamental electrode 3, followed by sintering. Next, on these fundamental electrodes 1 and 3, surface electrodes 2 and 4 composed of a triple-layer structure of Cu-plating/Ni-plat- ing/solder plating are formed by a non-electrolytic activating plating, thereby obtaining an element 5. The electrical characteristics are stable and a varistor voltage has no polarity, so that a change in the characteristics between before and after an assembly is extremely small and the characteristics are stable.

Description

[Detailed Description of the Invention] Industrial Application Field The present invention relates to capacitor characteristics and varistor characteristics for protecting semiconductors and circuits of electrical equipment and electronic equipment from normal high voltage, noise, and static electricity. The present invention relates to a voltage-dependent nonlinear resistance ceramic element.

Conventional technology Conventionally, SiC varistors with voltage-dependent nonlinear resistance characteristics have been used to absorb abnormally high voltages, remove noise, eliminate sparks, and counter static electricity in various electrical and electronic devices.
An nO type varistor is 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. Although such varistors have excellent performance in absorbing relatively high voltages, their low dielectric constant and small capacitance make them difficult to absorb relatively low voltages below the varistor voltage. It shows almost no effect, and 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 5×10 4 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 breaks down, and the capacitor no longer functions as a capacitor.

Recently, products containing 5rTiO+ 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 the pulls 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 mainly consists of S r T i 03, is used to remove noise that enters from a connector etc., the configuration of the element is generally as follows. It looks like Figure 3. In Figure 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. This has the disadvantage that the insulation resistance becomes low. In FIG. 4, 20 and 21 are electrodes, 23 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 polarity of the varistor voltage changes, and the insulation resistance does not change. The purpose of this invention is to provide an inexpensive element that has good properties and excellent soldering heat resistance.

Means for Solving the Problems In order to solve the above problems, in the present invention, 5rTi0
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 is provided that is small and has an inner circumference the same diameter as the through hole, 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. , electrodes are provided on the outer peripheral surface of the cylinder on the other end surface side of the cylinder, facing each other at a distance from the end surface; Ni plating, Cr plating, Sn plating.

Pb plating, solder plating, Au plating, Ag plating, P
The present invention attempts to solve this problem by obtaining a voltage-dependent nonlinear resistance ceramic element characterized by overlapping one or more of the D platings.

According to the configuration of the present invention, a donut-shaped electrode having an outer circumference smaller than the outer diameter of the cylinder and an inner circumference or the same diameter as the through hole is provided on one end surface of the cylinder, and the inner circumference of the through hole is An electrode is provided on the surface, the donut-shaped electrode and the electrode on the inner circumferential surface of the through hole are integrated, and the electrode is opposed to the outer circumferential surface of the predetermined cylinder at a distance from the end surface on the other end surface side of the cylinder. By adopting a configuration in which one end surface of the cylinder and the inner circumferential surface of the through hole are integrated as one electrode, some of the solder may be deposited in the gap between the pin and the element when it is assembled into a connector, etc. Even if it flows in, it is above the embodied electrode, so 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. In addition, by providing opposing electrodes on the outer peripheral surface of the cylinder on the other end surface side of the cylinder at a distance from the end surface, the surface insulation distance between the electrodes can be widened, so that the energized life characteristics can be improved. can be improved and reliability can be increased. Furthermore, in order to fully enhance the characteristics of the element, the electrodes are ohmic electrodes and the upper layers are Cu plating, N1 plating, Cr plating, Sn plating, and Pd plating.

By layering one or more of solder plating, Au plating, Ag plating, and Pd plating, it is possible to fully bring out the characteristics of the device without forming a barrier at the interface between the device and the electrode. It can be easily soldered, and the upper layer has a multilayer structure of a plurality of platings, so that the soldering heat resistance can be improved.

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

First, SrCO3, CaCO3, BaC0, iM g
CO3 and T i 02 were weighed at various composition ratios as shown in Table 1 below, and mixed in a whole mill for 20 hours. Next, after drying, it was baked at 1100°C for 3 hours, and then ground again for 20 hours using a ball mill, etc., and then dried.
Let it be the first component. Next, the first component, second component, and third component are weighed so that the composition ratios shown in Table 1 below are obtained,
After mixing for 20 hours using a ball mill, etc., drying, adding 10 wt% of an organic binder such as polyvinyl alcohol, and granulating it, press pressure of 1 (t/cd) to form particles with an outer diameter of 4φ, an inner diameter of 1.4φ, and a height of 2. It was formed into a cylindrical shape with a weight of .5 tons and baked in air at 1075°C for 10 hours to remove the binder. Next, a reducing atmosphere, for example N2: H2=
Calcinate in 9:1 gas at 1430°C for 4 hours. Furthermore, after that, the temperature is increased to 1035°C in an oxidizing atmosphere, e.g. air.
Bake for 4 hours.

On one end face of the sintered body obtained in this way, a donut-shaped electrode with an outer periphery smaller than the outer diameter of the cylinder and an inner periphery with the same diameter as the through hole is formed using a conductive paste such as ohmic Zn. is provided by, for example, screen printing, and an electrode is provided on the inner circumferential surface of the through hole by a method such as roller transfer, and the donut-shaped electrode and the electrode on the inner circumferential surface of the through hole are integrated. A base electrode 1 is formed as shown in FIG. Further, on the other end surface side of the cylinder, an electrode is provided on the outer circumferential surface of the cylinder, facing away from the end surface by a method such as roller transfer, to form a base electrode 3, and fired at 590° C. and 5 m1. . Next, an upper electrode 2.4 having a three-layer structure of Cu plating and N1 mesokey solder plating is applied to the lower electrode 1.3 by electroless activation plating.
is formed to obtain element 5.

When incorporating the element 5 into a connector, solder 7. as shown in FIG. Bin 6 by solder 13 etc.
and the common terminal 14 are attached, and the base electrode 8.10 and the upper base electrode 9,1 are connected with resin such as phthalene rubber (not shown).
The periphery of the element 12 provided with 1 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, V 1mA is the voltage applied to both ends of the element when a current of 1mA flows, and the polarity of Vl- is expressed as the difference between VlmA in the positive direction and V 1mA in the negative direction with Vlm, A in the positive direction. The insulation resistance is the applied voltage 12
This is the insulation resistance value between pin 6 and common terminal 14 at V, D, and C.

(Margins below) Here, although only a portion of the proportion of Sr in the first component to be replaced with Ca and BaMg was shown in the example, it is within the range where the element has both varistor and capacitor characteristics. It doesn't matter if it is something like ``to'' as long as it is inside.

Further, although only some combinations of the second and third components are shown in the embodiment, any component may be used as long as it has both varistor characteristics and capacitor characteristics as the element characteristics. Furthermore, in addition to Zn, Ag and Cu can be used as ohmic 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. Furthermore, the type of plating for the upper electrode may be any type as long as the top layer can be soldered, and the number of layers of plating may be one or more. I don't mind. Further, the plating method may be electrolytic plating or electroless plating, acid plating, basic plating, or neutral plating. The noise removal effect can be improved by connecting an inductance made of, for example, a ferrite, a coil, a toroidal coil, etc. 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 a distance from the end surface is formed on the outer circumferential surface of the cylinder on the other end surface side of the cylinder. By creating a structure in which electrodes are provided facing each other with a hole in between, one end surface of the cylinder and the inner circumferential surface of the through hole are integrated as one electrode, so that when assembled into a connector etc., the bottle and element Even if a part of the solder flows into the gap between the electrodes, the distance between the electrodes does not appear to change because the solder 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. You can get some effect. In addition, by providing opposing electrodes on the outer peripheral surface of the cylinder on the other end surface side of the cylinder at a distance from the end surface, the surface insulation distance between the electrodes can be widened, so that the energized life characteristics can be improved. reliability can be improved. Furthermore, by making the element cylindrical, the length of the element becomes longer, but the dimensions of the element can be reduced in the radial direction, making it possible to reduce the interval between the bins of the connector, making the connector more compact. It is effective for When the element is assembled into a connector or the like, since the common terminal can be soldered from both sides, the adhesive force between the common terminal and the element can be strengthened, and reliability can be improved. Furthermore, by connecting the common terminal to opposing electrode portions, the height protruding from the common terminal can be reduced. In order to fully bring out the characteristics of the element, the electrode is an ohmic electrode, and the upper layer is Cu plating, Ni plating, Cr plating, Sn plating, P plating, etc.
b plating, solder plating, Au plating, Ag plating, Pd
By layering one or more of the platings, the characteristics of the element can be fully brought out without forming a barrier at the interface between the element and the electrode, and it can be easily soldered. At the same time, the soldering heat resistance of the electrode can be improved.

[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, 2,4.9°11...Top electrode, 5,12...Element according to the present invention, 6...・・・Bottle, 7. Yu3...
...Solder, 14...Common terminal. Name of agent: Patent attorney Takuhei Awano (1 person) ? Jin, Bi11y

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 electrodes are provided on the outer circumferential surface of the cylinder on the other end surface side of the cylinder to face each other at a distance from the end surface, and the electrodes used for these have an ohmic electrode as the base and an ohmic electrode as the top. Cu plating, N
A voltage-dependent nonlinear resistor ceramic element characterized by having one or more platings stacked among i plating, Cr plating, Sn plating, Pb plating, solder plating, Au plating, Ag plating, and Pd plating. (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.