JPS62195110A - Ceramic capacitor - 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 [Field of Industrial Application] The present invention relates to a ceramic capacitor with high equal series resistance.

[Conventional technology]

For example, Power I used in car radios and car stereos.
C. oscillation prevention capacitors require relatively high (for example, 1 to several ohms) equal series resistance, and for this reason, the following measures have been conventionally adopted.

(2) A resistor with a resistance value of q to several ohms is connected in series to a ceramic or film capacitor having a capacitance of, for example, about 0.1 μF.

■ A resistor is formed as a thin film inside a ceramic capacitor, making it look like a single capacitor element.

To explain this with reference to FIG. 2, in this ceramic capacitor 2, electrodes (for example, silver electrodes) 6a and 6b are formed on both main surfaces of a plate-shaped ceramic 4 to form a capacitor. For example, a resistor paste is printed as a resistor (resistance film) 8 on an electrode, for example, an electrode 6a,
Furthermore, a secondary electrode 10 for soldering is formed thereon, and lead wires 14a, 14b are connected to the secondary electrode 10 and the electrode 6b.
are soldered with solder 12, and finally, an exterior resin 16 is applied by dipping or the like.

Therefore, in the ceramic capacitor 2, as the equivalent circuit thereof is shown in FIG. 3, relatively large equal series resistors R are formed in series with the capacitance C.

■ Use capacitors that themselves have equal series resistance, such as aluminum electrolytic capacitors.

[Problem that the invention seeks to solve]

However, in the above method (■), the number of parts is 2.
(ie, capacitor and resistor), resulting in higher cost. Furthermore, in the above method (2), the processing (manufacturing) method is complicated and the cost is high. Furthermore, in the above method (2), the productivity is low and the cost is high.

Therefore, an object of the present invention is to provide a capacitor that is inexpensive and has a high equal series resistance.

[Means for solving problems]

In the ceramic capacitor of this invention, aluminum electrodes are formed on both sides of a plate-shaped ceramic, secondary electrodes for connecting wires are formed on both aluminum electrodes, and lead wires are connected to both secondary electrodes. A ceramic capacitor formed by bonding is characterized in that the aluminum electrode is baked into the ceramic at a firing temperature of 700° C. or more and 840° C. or less.

[Effect]

By using aluminum electrodes as the electrodes formed on the bidirectional surfaces of the ceramic, and by setting the firing temperature of the ano□reminium electrodes within the above range, a capacitor with high equal series resistance was obtained.

〔Example〕

FIG. 1 is a sectional view showing a ceramic capacitor according to an embodiment of the present invention. This ceramic capacitor 2
In No. 0, aluminum electrodes 26a and 26b are formed on both sides of the plate-shaped ceramic 4, and secondary electrodes (for example, silver electrodes) are used to solder the lead wires 14a and 14b to both aluminum electrodes 26a and 26bl. 1
0a and 10b are formed, lead wires 14a and 14b are soldered to both secondary electrodes 10a and 10b with, for example, solder 12, and an exterior resin 16 is applied by dipping or the like as necessary.

The ceramic 4 is, for example, a grain boundary insulation type semiconductor ceramic, but may also be a normal dielectric ceramic.

The aluminum electrodes 26a and 26b are made by applying a sintered electrode material containing aluminum powder as a main component to the ceramic 4 and firing it, for example.

In that case, the firing temperature of the aluminum electrodes 26'a and 26b is set at 700°C to 88°C, which is slightly lower than normal (850°C).
By keeping the temperature within the range of 40° C., a ceramic capacitor 20 with high equal series resistance was obtained.

A more specific example is shown below (dimensions are in mm).

Ceramic 4 has a diameter of 8.4φ, a thickness of 0°3t, and a capacity of 10 when the silver electrode is formed with a size of 7.7φ.
A grain boundary insulated semiconductor ceramic having a dielectric loss of 0 nF' and a dielectric loss of 0.4% (atI KT(z)) was used.

Then, aluminum paste was printed and coated on the ceramic 4 with a diameter of 7.7φ, and the firing temperature was 850°C (conventional standard temperature), 8'40°C, 780°C, 770°C, 760°C,
Aluminum electrode 26 at each temperature of 750°C and 700°C
A and 26b were baked. In that case, the holding time at each temperature was 20 minutes.

After that, the secondary electrode 1', Oa, 10b, lead wire 14a
, 14'b, etc., to obtain a ceramic capacitor 20 having a structure as shown in FIG.

On the other hand, a capacitor with a structure as shown in Fig. 2 was used as a monitor. That is, a silver electrode formed with a diameter of 7.7 on the ceramic 4 as described above (capacity 100 nF, dielectric loss 0).
．． A thin film resistor paste having a resistance value of about 1 Ω was printed on one side of the resistor 8 (4% at IKHz) as a resistor 8, and a secondary electrode 10, lead wires 14a, 14b, etc. were added to obtain the monitor.

The characteristics of each sample as described above are shown in a table.

(Left below) As can be seen from this table, in the ceramic capacitor 20 having the structure shown in FIG. 1, the aluminum electrodes 26a, 2
As the firing temperature of 6b is lowered, the equivalent series resistance becomes higher. However, if the firing temperature is too low, other properties such as capacity will decrease, so the firing temperature should be 700℃ to 840℃.
It is preferable to keep it within the range of .

As described above, in this ceramic capacitor 20, the aluminum electrodes 26a, 26
Since the desired capacitor with high value series resistance can be obtained simply by lowering the firing temperature of b from the standard one, the cost can be reduced.

Further, by changing the firing temperature, it is possible to aim for an arbitrary equivalent series resistance, although there are upper and lower limits.
゛The relationship between the firing temperature and the equivalent series resistance varies to some extent depending on the holding time at that temperature (for example, to obtain the same equivalent series resistance, the shorter the holding time, the higher the temperature). It is also possible to adjust the series resistance.

〔Effect of the invention〕

As described above, according to the present invention, a capacitor that is inexpensive and has a high equivalent series resistance can be obtained.

[Brief explanation of drawings]

FIG. 1 is a sectional view showing a ceramic capacitor according to an embodiment of the present invention. FIG. 2 is a sectional view showing an example of a conventional ceramic capacitor with a high equivalent series resistance. FIG. 3 is an equivalent circuit diagram of the ceramic capacitor shown in FIG. 2. 4... Ceramic, 10a, 10b... Secondary electrode,
14a, 14b... Lead wire, 20... Ceramic capacitor according to the example, 26a, 26b... Aluminum electrode

Claims (1)

[Claims] (1) Form aluminum electrodes on both main surfaces of a plate-shaped ceramic, form secondary electrodes for connecting lead wires on both aluminum electrodes, and connect lead wires to both secondary electrodes. A ceramic capacitor consisting of a ceramic capacitor, wherein the aluminum electrode
A ceramic capacitor characterized in that it is formed by firing the ceramic at a firing temperature of 0.degree. C. or less.