JPS5848907A - Ceramic laminate - Google Patents

Abstract

(57) [Summary] This bulletin contains application data before electronic filing, so abstract data is not recorded.

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention provides a structure in which ceramic electronic material layers and metal conductor layers are alternately laminated, in which one or more of the ceramic electronic material layers is a high permittivity dielectric material mainly composed of barium titanate. The present invention relates to a ceramic laminate characterized in that the remaining layers are voltage nonlinear resistors mainly made of zinc oxide.

A typical example of a ceramic laminate is a 2-layer multilayer capacitor. This multilayer ceramic capacitor has a structure in which dielectric layers and metal conductor layers are alternately laminated, and every other metal conductor layer is stacked so that each dielectric layer is electrically parallel. The electrodes will be facing each other,
Each of them has a structure connected to metal conductors at both ends.

Since such a laminated ceramic has a structure in which one dielectric film layer is connected in parallel, it is characterized by an extremely large capacitance per volume. That is, in general, the capacitance of a capacitor is C εε. Represented below. Here, ε is the dielectric constant and distance of the dielectric. Therefore, the capacitance per volume increases in inverse proportion to the square of the thickness of the dielectric layer.

Usually, a dielectric layer having a thickness of about 20 to 100 microns is used in multilayer ceramic capacitors.

Such capacitors have recently come to be used in large numbers in electronic circuits using ICs and the like, and are now playing an active role as essential parts of electronics.

However, the problem with multilayer ceramic capacitors in which such dielectric film layers are laminated is that the thickness of each dielectric film layer is approximately 20 to 100 μm.
Because they are vulnerable to high voltages and can be destroyed, protection circuits are required at locations where abnormal voltages occur.

As a result of various studies in consideration of the above-mentioned drawbacks, the present invention has been able to provide a ceramic laminate that can be used as a multilayer ceramic capacitor that is extremely resistant to abnormal voltages.

Furthermore, the ceramic laminate of the present invention can be used not only as a noise absorbing element but also as a noise absorbing element. In other words, since the capacitor and voltage nonlinear resistor are connected in parallel, it is possible to absorb abnormal frequency bands and abnormal voltages by selecting an appropriate capacitance and appropriate varistor voltage. be. Here, the varistor voltage refers to a rising voltage in the voltage-current characteristics of a voltage non-linear resistor, which is a voltage value usually at 1 mA. Such a noise absorbing element can be used for applications such as preventing noise generation in micro motors.

The ceramic laminate of the present invention as described above will be described in detail below based on Examples.

First, a mixed powder consisting of 70 parts by weight of barium titanate, 10 parts by weight of calcium titanate, 20 parts by weight of barium zirconate, and 0.2 parts by weight of zinc oxide was added with 20 parts by weight of ethyl cellulose and 80 parts by weight of butyl calpitol. A slurry of 3,000 to 5,000 centipoise was prepared by adding an organic binder of
A sheet of 0μ was produced. Further, a sheet having a thickness of 80 μm was produced in the same manner using a mixed powder consisting of 98.6 parts by weight of zinc oxide, 1 part by weight of cobalt oxide, and 0.6 parts by weight of manganese dioxide. Each of the above sheets is 50mm x
It was cut into a size of 100mrn7), and an electrode paste mainly composed of palladium was screen printed on one side of the cutout. After this, sheets mainly composed of barium titanate and sheets mainly composed of zinc oxide were laminated together with sheets printed with electrode paste and sheets not printed, cut and baked at 1350°C for 2 hours. did. Figures 1A and 1B show the ceramic laminates obtained in this way,
In the figure, 1 is a dielectric layer mainly made of barium titanate, 1'
2 is a dielectric layer mainly made of barium titanate, which is made of a sheet on which no electrode paste is printed; 2 is a dielectric layer mainly made of zinc oxide; and 3 is a conductive layer mainly made of palladium. Here, the conductor layers 3 are provided alternately. In addition, the shape of this ceramic laminate has a length of 3 m.
m x width 1.6 mm x thickness Q 64 mm.

Next, silver electrodes were provided on both end faces of the ceramic laminate thus obtained. FIG. 2 shows a multilayer ceramic capacitor manufactured using this method, and 4 is a silver electrode.

The characteristics of the multilayer ceramic capacitor obtained as described above were that the capacitance was 1 KH2, 23000 pF, and tan δ was 6.7%. Furthermore, the voltage-current characteristics are shown in FIG. As is clear from this figure, 60 cm is the rising voltage, and at a voltage higher than this, it becomes a low resistance element. Furthermore, as shown in Figure 4, a 1 Kv pulse was applied for 10 milliseconds.
The capacitor does not lose its function even after 104 applications.

Furthermore, even when a 10 Kv pulse is applied for 1 millisecond, it can withstand at least 102 times of application. In addition, in Fig. 4, Δc
/c is the rate of change in capacitance.

Here, in the following embodiments, as shown in FIG. 1, the case where the dielectric layer 1 mainly made of barium titanate is four layers has been described, but it is sufficient that the dielectric layer 1 is one or more layers, and the remaining The layer may be composed of a dielectric layer 2 mainly made of zinc oxide.

As described above, the ceramic laminate of the present invention can withstand high voltage and has the functions of both a voltage nonlinear resistor and a capacitor, so it can be used as a small and compact noise absorbing element. The industrial value is enormous.

[Brief explanation of drawings]

1A and 1B are perspective views and cross-sectional views showing one embodiment of the ceramic laminate according to the present invention, FIG. 2 is a perspective view of a multilayer ceramic capacitor using the same ceramic laminate, and FIG. FIG. 4 is a voltage-current characteristic diagram of the multilayer ceramic capacitor, and FIG. 4 is a pulse characteristic diagram of the same ceramic capacitor. 1.1'...Dielectric layer mainly composed of barium titanate, 2...Dielectric layer mainly composed of zinc oxide, 3...Metal conductor layer. Name of agent: Patent attorney Toshio Nakao and one other person? (F3) Fig. 2 Fig. 3 → /l Pressure (Holt) Fig. 4 Number of times per discharge tJU (times)

Claims (1)

[Claims] Ceramic electronic material layers and metal conductor layers are alternately laminated, one or more of the ceramic electronic material layers is composed of a dielectric layer mainly composed of barium titanate, and the remaining layers are composed of a dielectric layer mainly composed of zinc oxide. A ceramic laminate consisting of body layers.