JPS6221255B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming electrodes of a ceramic capacitor in which an electrode margin is formed at the peripheral edge of an end face of a dielectric ceramic substrate using ultrasonic waves.

Generally, in a ceramic capacitor, as shown in FIG.
is provided, and the creepage distance between the electrodes 1 and 2 is increased to obtain a predetermined dielectric strength.

Conventionally, as shown in FIG. 2a, as a method for forming electrodes of this type of ceramic capacitor, an electrode film 12 is formed on the entire surface of a dielectric ceramic substrate 11 by an electroless plating method, etc. A large number of substrates 11 are stacked, and as shown in FIG. 2b, the entire body is coated with wax or resin to form a rod-shaped laminate 13, and the electrode film 12' on the outer peripheral surface of the laminate 13 and the electrode film 12' on the outside thereof are coated with wax or resin. After removing the wax or resin by centerless grinding or the like as shown in FIG. The electrode film 1 on the peripheral edge of the end surface of each dielectric ceramic substrate 11 is immersed in a mixed solution of
2, and then the wax or resin between the dielectric ceramic substrates 11 is melted to form an electrode 12a having electrode margins 14, 14 on the peripheral edge of the end face of the dielectric ceramic substrate 11, as shown in FIG. 2d. ,12
There are known ones that form b.

The above electrode forming method allows the size of the electrode margins 14, 14 to be arbitrarily set by adjusting the concentration of the mixed solution, immersion time, etc. This has the advantage that the opposing area between the electrodes 12a and 12b becomes larger and the capacitance can also be increased, but the thickness of the electrode film 12 is usually as thin as 1 μm to 2 μm, as shown in FIG. As the gap between the wax or resin and the dielectric ceramic substrate 11 becomes narrower, it becomes difficult for the solution of the electrode film 12 to penetrate. Also, it is necessary to increase the temperature and lengthen the soaking time.

However, if this is done, as shown in FIG. 4, the wax or resin must be able to withstand high temperatures, at which the dissolving liquid corrodes the dielectric ceramic substrate 11 itself, and the materials are limited. Problems arise, such as the time it takes to form the electrode margins 14, 14.

The present invention has been made to eliminate the above-mentioned problems in the conventional method of forming electrodes for ceramic capacitors. After removing the wax or resin on the outer peripheral surface of the laminate, the laminate is immersed in a solution of the electrode film that has been subjected to ultrasonic vibrations and rotated to separate both planes of each dielectric ceramic substrate except for the vicinity of the outer periphery. By removing the remaining electrode film while leaving the remaining electrode film, ultrasonic vibrations are applied to the solution of the electrode film to promote dissolution of the electrode film in the electrode margin area, reducing the time required to form the electrode margin. While aiming to shorten the time, we have developed a ceramic capacitor that uses a solution with low concentration and temperature to prevent erosion of the dielectric ceramic substrate by the solution, and to alleviate the limitations of wax or resin materials due to the temperature of the solution. The object of the present invention is to provide a method for forming an electrode.

Hereinafter, an embodiment of the present invention will be explained in detail with reference to FIGS. 5a to 5d.

First, a dielectric ceramic substrate 1 is fired into a disk shape.
1 is immersed in an electroless nickel plating solution to form a nickel metal film 12 on the entire surface of the dielectric ceramic substrate 11, as shown in FIG. 5a.

As mentioned above, a large number of dielectric ceramic substrates 11, . As shown in the figure, coat the entire body with microcrystalline wax 1.
5 to form a round bar-shaped laminate 13.

The thus produced laminate 13 is applied to a centerless grinder (not shown) to remove the microcrystalline wax 15 on the outer periphery of the laminate 13, as shown in FIG. , 11 are ground, and the electrode film 12 of each dielectric ceramic substrate 11 is separated into two electrodes 12a and 12b, respectively.

In this case, the dielectric ceramic substrates 11,..., 11
The opposing area of the electrodes 12a and 12b is adjusted by the amount of grinding, so that the ceramic capacitor to be manufactured has a desired capacity.

Next, the laminated body 13 processed as shown in FIG.
As shown in FIG. 5d, another similar laminate 1
3,..., 13, the ferric chloride was housed in a barrel 16 with many holes in its circumferential surface and subjected to ultrasonic vibrations 18 by an ultrasonic vibrator 17 diluted to about 20%. The above barrel 1 is immersed in an aqueous solution 19.
6 in the direction of the arrow, each laminate 13,...,1
3 to melt the electrode films 12 on the peripheral edges of both end faces of each dielectric ceramic substrate 11.

Thereafter, the laminates 13, . . . , 13 are pulled up and thoroughly washed with water, and finally the microcrystalline wax 15 is washed with trichlorethylene to separate the dielectric ceramic substrates 11, .
A ceramic capacitor element similar to that shown in Figure d was obtained.

When the electrodes 12a and 12b of the ceramic capacitor are formed as described above, the dimensions of the electrode margins 14 and 14 with respect to the immersion time are as shown by the curve g in FIG. 6 when the temperature of the ferric chloride aqueous solution 19 is 25°C. ₁ , and for example, when the immersion time is 10 minutes, the dimensions of the electrode margins 14, 14 are about 0.27 mm. In this case, the frequency of the ultrasonic wave applied to the aqueous solution 19 is
It was 28KHz.

On the other hand, when the temperature of the ferric chloride aqueous solution 19 is 50°C and 25°C and no ultrasonic vibration is applied, the curves g ₂ and g ₃ in Fig. 6 are obtained, respectively, and the immersion time is 10°C. The electrode margins 14, 14 are about 0.07 mm when the temperature is 50°C and about 0.04 mm when the temperature is 25°C.

Therefore, even if the temperature of the aqueous solution 19 is as low as about 25° C., when ultrasonic vibration is applied to the aqueous solution 19, the dimensions of the electrode margins 14, 14 will be different compared to when no ultrasonic vibration is applied. It can be seen that the value is about 4 to 7 times (immersion time 10 minutes), and the time for forming the electrode margins 14, 14 is greatly shortened.

Further, in this embodiment, since the barrel 6 is rotated to rotate the stacked body 13, the electrode 12 is rotated.
a, 12b are uniformly dissolved, and the electrode margins 14,
The dimensions of 14 will not be non-uniform. This means that if ultrasonic vibration is applied while the laminate 13 is stationary, the peripheral edge of the end face of the dielectric ceramic substrate 11 cannot be uniformly melted.

In the above embodiment, the electrode film 12' on the outer peripheral surface of the dielectric ceramic substrate 11 was ground using a centerless grinder, but it may be ground so as to leave the electrode film 12' on the outer peripheral surface. In this case, the electrode 12' on the outer peripheral surface
may be removed at the same time as the electrode film on the peripheral edge of the end face is melted while applying ultrasonic vibration in a later step. That is, when exposing the outer peripheral surface of the dielectric ceramic substrate, the electrode film may be left or removed.

In the above embodiments, the laminate 13 is immersed in the ferric chloride solution 19 after completely removing the wax on the surface of the outer circumference, but after grinding, excess wax, machine oil, and porcelain powder are removed. If the solution is washed with a solvent such as alcohol, acetone, or trichlorethylene and then immersed in dilute acid, the solution will not get dirty, leading to improved dissolving power and sustainability of the dissolving ability of the plated metal.

Furthermore, although nickel plating has been described in the examples, the same applies to other metal platings, such as silver, tin, copper plating, etc., and does not depart from the intent of the present invention. Similar effects can be obtained with dilute acids, etc. Furthermore, the removal of organic matter from the outer periphery of the plated dielectric ceramic substrate does not involve mechanical grinding, but the same result can be obtained by dissolving and removing the organic matter with a solution that dissolves the organic matter.

As is clear from the above detailed explanation, the present invention provides ultrasonic waves while rotating a laminate which is coated with wax or resin and whose outer periphery is removed to expose the outer periphery of a dielectric ceramic substrate. Since electrode margins are formed around the edge of the dielectric ceramic substrate by immersing it in a vibrating solution, the treatment can be performed even at low concentrations and water temperatures of the solution using ultrasonic waves. Temperature restrictions on waxes and resins are eased, reducing material costs and erosion of dielectric ceramic substrates. Ultrasonic vibrations can form the necessary electrode margins in a short time, increasing productivity. At the same time, erosion of the dielectric ceramic substrate is further reduced. Ultrasonic output can be adjusted to adjust the electrode margin, making it easier to control the temperature of the solution, reducing production equipment costs and savings. The effects are extremely large, such as being able to generate energy.

[Brief explanation of the drawing]

Figure 1 is a cross-sectional view showing the structure of a ceramic capacitor.
Figures 2a to d are explanatory diagrams of a conventional method for forming electrodes of a ceramic capacitor, Figure 3 is an explanatory diagram of the process of forming an electrode margin, Figure 4 is an explanatory diagram showing erosion of a dielectric ceramic substrate, and Figure 5 is an explanatory diagram of the formation process of an electrode margin. Figures a to d are explanatory diagrams of the method for forming electrodes of a ceramic capacitor according to the present invention, respectively.
The figure is a diagram showing the correlation between the time for immersing the dielectric ceramic substrate in a solution after grinding its outer circumference and the dimensions of the electrode margin. 11... Dielectric ceramic substrate, 12... Electrode film, 12
a, 12b...electrode, 13...laminate, 14...electrode margin, 16...barrel, 17...ultrasonic transducer.

Claims (1)

[Claims] 1. An electrode film is deposited on the entire surface of a plate-shaped dielectric ceramic substrate, and these dielectric ceramic substrates are laminated and the whole is coated with wax or resin to form a rod-shaped laminate, and the outer peripheral surface of the laminate is coated with an electrode film. wax or resin,
Alternatively, the wax or resin on the outer peripheral surface of the laminate and the electrode film on the outer peripheral surface of the dielectric substrate are removed, and the laminate is immersed in a solution of the electrode film subjected to ultrasonic vibration and rotated. , After removing the remaining electrode film leaving the electrode film on both planes except near the outer peripheral surface of each dielectric ceramic substrate, the wax or resin between the dielectric ceramic substrates is removed to separate each dielectric ceramic substrate. A method for forming electrodes of a ceramic capacitor, characterized by: