JPH0442504A - Voltage dependent nonlinear resistance porcelain element - Google Patents

Abstract

PURPOSE:To facilitate soldering and to improve a solder heat resistance by uniting a doughnut-form electrode of a semiconductor ceramic cylinder with an electrode on an inner circumferential plane into one body and arranging a counter electrode on an outer circumferential plane on another end plane side at a distance from the end plane, wherein a fundamental electrode is an ohmic electrode and a non-ohmic electrode is overlaid as an upper one. CONSTITUTION:On one end plane of a sintered body, a doughnut-form electrode is arranged by using an ohmic conductive paste such as Ag as a fundamental one, and an ohmic electrode is arranged on an inner circumferential plane of a through-hole, and these electrodes are united into one body. On another end plane side of a cylinder, a counter ohmic electrode is arranged at a distance from the end plane, thereby forming a fundamental electrode 3. As an upper electrode, upper electrodes 2 and 4 consisting of a non-ohmic electrode is formed by using a non-ohmic paste, followed by sintering to make an element 5. Then, a pin 6 and a common terminal 14 are attached with a solder 7 and a solder 13 and a periphery around an element 12 where fundamental electrodes 8 and 10 and upper electrodes 9 and 11 are arranged is molded with a resin.

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. The present 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) α Here, ■ is a current, ■ is a 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, but because of their low dielectric constant and small static capacitance, they cannot absorb relatively low voltages below the varistor voltage. 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 is destroyed, and the capacitor no longer functions as a capacitor.

Recently, a product containing 5rTjO:+ as a main component and having both varistor and capacitor characteristics has been developed, and it is used as an IC in electronic devices such as computers.
It is used to protect semiconductor elements and circuits such as LSIs, and to remove noise that enters from cables and connectors that interconnect electronic devices.

Problems to be Solved by the Invention When using the above-mentioned SrTiO3-based element having the functions of both a varistor and a capacitor to remove noise that enters from a connector etc., the configuration of the element is generally as shown in Fig. 3. It looks like this. 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. 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 varistor voltage does not have polarity, and the insulation resistance does not change, and the electrodes can be easily formed. The purpose is to provide an inexpensive element that has good soldering properties and excellent soldering heat resistance.

Means for Solving the Problems In order to solve the above problems, in the present invention, 5rTiO
: A semiconductor ceramic having a voltage-dependent nonlinear resistance characteristic mainly composed of + 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 that is similar to that of the cylinder. A donut-shaped electrode is provided whose inner circumference is smaller than the outer diameter of the through hole and has 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 inner circumferential surface of the through hole are provided with an electrode. The electrodes 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 on the base and an ohmic electrode on the top surface. The present invention attempts to solve this problem by obtaining a voltage-dependent nonlinear resistance ceramic element characterized by stacking non-ohmic electrodes.

According to the configuration of the present invention, a donut-shaped electrode is provided on one end surface of the cylinder, the outer periphery of which is smaller than the outer diameter of the cylinder, and the inner periphery of which is the same diameter as the through hole. An electrode is provided on the surface, and the donut-shaped electrode and the electrode on the inner circumferential surface of the through hole are integrated, and on the other end surface side of the cylinder, they are opposed to each other at a distance from the end surface on the outer circumferential surface of the cylinder. By configuring the structure with electrodes, one end surface of the cylinder and the inner peripheral surface of the through hole are integrated as one electrode, so when it is assembled into a connector etc., a drop of solder is applied to the gap between the pin and the element. Even if the part flows in, the distance between the upper electrodes does not appear to change because it is above the integrated electrode. 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 circumferential 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 etc. reliability can be improved. Furthermore, in order to fully bring out the characteristics of the element, the electrode is configured with an ohmic electrode as the base layer and a non-ohmic electrode on the upper layer, thereby eliminating the formation of a layer at the interface between the element and the electrode. This means that the characteristics of the element 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: +, CaCO3, BaCO3゜MgC
O3 and TiO2 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 is baked at 1120° C. for 4 hours, pulverized again for 22 hours using a ball mill, etc., and then dried to obtain 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 in a ball mill for 22 hours, dried, and mixed with an organic binder such as polyvinyl alcohol. After adding 1Qwt% and granulating it, it was molded into a cylindrical shape with an outer diameter of 4φ, an inner diameter of 1.4φ, and a height of 2.5t (+am) at a press pressure of 1 (t/cut), and heated at 1110°C in air. The binder was removed by firing for 11 hours. Next, a phosphorescent, optical atmosphere, for example N2: H2=9
: Calcinate in gas of 1 at 1420°C for 5 hours. Furthermore, after that, 5 hours at 1050°C in an oxidizing atmosphere, e.g. air.
Bake for hours.

On one end surface of the sintered body thus obtained, a donut-shaped electrode is formed using a conductive paste such as ohmic Ag as a base, 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. is provided by, for example, screen printing, and an ohmic electrode is provided on the inner peripheral surface of the through hole by a method such as roller transfer, and the donut-shaped electrode and the electrode on the inner peripheral 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 ohmic 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 the base electrode 3. Next, an upper electrode 24 made of a non-ohmic electrode is formed using the same method as that of forming an ohmic electrode on an ohmic electrode using a non-ohmic paste such as A or G as an upper layer.
is formed and fired 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. Pin 6 with 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 the connector is assembled.

In Table 2, Vl, nA is the voltage applied to both ends of the element when a current of 1 mA flows, and the polarity of ■1□ is the difference between VlmA in the positive direction and ■1□ in the negative direction. V
It is the value divided by lmA, and the insulation resistance is the applied voltage of 12 V.
, D, and C are the insulation resistance values between pin 6 and common terminal 14.

(Hereafter, remaining white) Here, part of the first component Sr is Ca and Ba.

Although only a portion of the substitution ratio with Mg was shown in the embodiment, it may be any value as long as the element has both varistor and capacitor characteristics. 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. Further, as the ohmic electrode, there are Zn, CuN1, etc. other than Ag, 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, 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 an electrode is provided on the outer circumferential surface of the cylinder on the other end surface side of the cylinder at a distance from the end surface. By creating a configuration in which a hole is opened and opposing electrodes are provided, one end surface of the cylinder and the inner peripheral 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. Effects can be obtained. 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 front common terminal to the opposing electrode portion, the height protruding from the common terminal can be reduced. In order to fully bring out the characteristics of the element, the electrodes are constructed with an ohmic electrode on the base layer and a non-ohmic electrode on the upper layer. The characteristics of the electrode can be fully brought out, it can be easily soldered, and the soldering heat resistance of the electrode can be improved.

[Brief explanation of 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 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...
・Solder, 14... Common terminal. Name of agent: Patent attorney Takuhei Awano and one other person Figure 3 Figure 4

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 peripheral 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 on the base and an ohmic electrode on the top surface. A voltage-dependent nonlinear resistance ceramic element characterized by stacking non-ohmic electrodes. (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.