JPS6313330B2 - - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION The present invention relates to a method for forming a nickel layer on a ceramic body such as a ceramic capacitor by electroless plating.

If the electrodes of a ceramic capacitor are formed by the known silver baking method, electrodes with excellent electrical characteristics and solderability can be obtained, but on the other hand, it is difficult to mass produce and silver is expensive. It is inevitable that the cost of the completed ceramic capacitor will be high. In order to solve this drawback, a method has been proposed in which capacitor electrodes are formed by electroless plating. However, it has been difficult to form a nickel layer with good adhesion.

Therefore, an object of the present invention is to provide a method that can easily form a nickel layer that has good adhesion to a ceramic body.

To achieve the above object, the present invention heat-treats a porcelain body that has been immersed in an activator for electroless nickel plating and pulled up at a temperature of 80 to 600°C for 5 to 60 minutes, and then performs electroless nickel plating treatment. The present invention relates to a method for forming a nickel layer on a porcelain body.

According to the above invention, when electroless nickel plating is applied after heat treating the porcelain body immersed in the activator at 80 to 600°C, the adhesion of the nickel layer to the porcelain body improves.

Hereinafter, one embodiment of the present invention will be described with reference to the drawings.

First, a disc-shaped ceramic body 1 made of, for example, a barium titanate dielectric material as shown in FIG. 1A is prepared.

Next, the porcelain body 1 shown in FIG. 1A is washed with a neutral detergent.
Clean with organic solvents, inorganic acids (nitric acid, hydrofluoric acid), etc. to remove dirt from the element body.

After the above washing step is completed, the sample is treated with a sensitizer containing stannous chloride (SnCl ₂ ) at room temperature for 3 to 5 minutes.

Next, with water, and then with an activator (activator) containing palladium chloride (PdCl ₂ ) at a ratio of 0.07 to 0.4 grams in an aqueous solution of 40 to 60%.
Activation treatment is performed for 3 to 5 minutes at ℃. Next, it is washed with water and then heat treated at a temperature of 80 to 600°C for 5 to 60 minutes. As a result, the porcelain element 1 dries and the palladium film adheres to the porcelain element 1.

Next, as shown in FIG. 1B, the outer circumferential surface 2 of the porcelain body 1, which is the non-electrode forming area, is made of a thermosetting resin, such as an epoxy resin, or a photocurable resin, which has good moisture resistance and high adhesion strength. An insulating layer 3 made of resin or the like is provided. This insulating layer 3 may be formed of any material as long as it has moisture resistance, electrical insulation, and chemical resistance.

Next, the porcelain body 1 is immersed in an electroless plating solution containing sodium hypophosphite (NaH ₂ PO ₂ ) and nickel sulfate (NiSO ₄ ), and a nickel layer 4 with a thickness of 2 μm or more is formed as shown in FIG. Form as shown in C. This electroless plating is performed by a chemical change as shown in the following formula.

NaH ₂ PO ₂ +H ₂ O→NaH ₂ PO ₃ +H ₂ NaH ₂ PO ₃ +NiSO ₄ →Ni+H ₂ SO _{4 +} NaPO Generates Nickelmecki.

Once the nickel layer 4 shown in FIG. 1C has been formed, the porcelain element 1 is plated for heat treatment.
is placed in a furnace and subjected to heat treatment at a temperature of 200 to 400°C for 5 to 60 minutes. This heat treatment is performed in the air or in a neutral atmosphere (argon or carbon dioxide gas).

Next, the first layer is plated using electroplating or electroless plating.
As shown in Figure D, a solder plating layer 5 is formed on the nickel layer 4.
are formed to form the first capacitor electrode 6 and the second capacitor electrode 7. Thereafter, terminal members (not shown) are connected to the electrodes 6 and 7 by soldering or the like to complete the device.

When a ceramic capacitor is manufactured by the above method, the masking insulating layer 3 is provided after the plating is activated with a sensitizer and an activator, so that the surface of the masking insulating layer 3 is covered with the sensitizer and activator. The element body 1 is placed in an electroless nickel plating solution with a masking insulating layer 3 without being activated by an activator.
Even if the masking insulating layer 3 is dipped, hardly any nickel will adhere to the surface of the masking insulating layer 3, and the masking insulating layer 3 can be used as it is for moisture proofing, solder flow prevention, etc.

In addition, in this example, after treatment with an activator, heat treatment is performed at 80 to 600°C to increase the adhesion strength of palladium to the porcelain body 1, so the palladium film is affected by the masking insulating layer 3. Not only is it not affected by nickel layer 4, but it is also
The adhesion force to will be increased.

Note that if the heat treatment temperature immediately after the activator treatment is lower than 80° C., the adhesion strength of palladium (activator) to the ceramic body 1 will also be low. When the heat treatment temperature is set to 80° C. or higher, the adhesion strength of palladium increases, and as the heat treatment temperature increases, the adhesion strength of palladium also improves. However, the improvement in adhesion strength reaches a saturation point at about 500°C. On the other hand, the catalytic activity of the activator (palladium) gradually decreases when the heat treatment temperature exceeds 400°C, and rapidly decreases when the temperature exceeds 600°C. For this reason, when heat treatment is performed at a temperature exceeding 600°C, the nickel film deposited by the reduction action becomes sparse. Therefore, it is desirable that the above heat treatment temperature be in the range of 80 to 600°C.

Although one embodiment of the present invention has been described above, the present invention is not limited to the above-described embodiment and can be further modified. For example, as shown in FIG. 2, the cylindrical ceramic body 1 is subjected to plating activation treatment, and the insulating layer 3 is provided on the non-electrode forming surface 2a.
It is also applicable to a structure in which a nickel layer 4 and a solder plating layer 5 are then formed by electroless plating to form the first capacitor electrode 6 on the inside and the second capacitor electrode 7 on the outside.

Further, instead of the solder plating layer 5, a silver layer or the like having good solderability may be provided. Further, a nickel layer may be further provided by electroplating on the nickel layer 4 formed by electroless plating, and a metal layer having good solderability such as solder or silver may be provided thereon.

In addition, if it is undesirable that the palladium film formed in the activation process for plating remains between the insulating layer 3 and the element body 1, the palladium film formed on the outer circumferential surface of the element body 1 after the activation process for plating is Alternatively, the insulating layer 3 is provided after the non-electrode forming surface 2a is slightly polished, or an easily peelable film is provided on the outer peripheral surface 2 or the non-electrode forming surface 2a before the activation treatment for plating, and the activation treatment for plating is performed. This film may be peeled off later, and then a moisture-resistant insulating layer 3 that remains until the end may be provided.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing a ceramic capacitor according to an embodiment of the present invention in the order of steps, and FIG. 2 is a sectional view showing a modified example. In the symbols used in the drawings, 1 is the ceramic body, 2 is the outer peripheral surface, 3 is the insulating layer, 4 is the nickel layer, 5 is the solder plating layer, 6 is the first capacitor electrode, and 7 is the first capacitor electrode. This is the second capacitor electrode.

Claims (1)

[Claims] 1. A porcelain element which is immersed in an activator for electroless nickel plating and pulled up, heat-treated at a temperature of 80 to 600°C for 5 to 60 minutes, and then subjected to electroless nickel plating treatment. How to form a nickel layer.