JPH0574614A - Manufacture of ceramic electronic component - Google Patents

Abstract

PURPOSE:To manufacture an element like a positive temperature coefficient thermistor of high yield and high reliability, without forming Ni-plating on the side surface of a semiconductor ceramic. CONSTITUTION:The side surface of a columnar semiconductor ceramic is coated with paraffin, and Ni-plated electrodes are formed on both flat surfaces of the semiconductor ceramic by an electroless Ni-plating method. After that, heat treatment is performed, thereby manufacturing a ceramic electronic component. By the effect of paraffin as the mask material of Ni-plating, it can be easily evaded that Ni-plating is formed on the side surface of the semiconductor ceramic. Since the paraffin is evaporated during heat treatment, a special process for eliminating paraffin is not necessary, so that ceramic electronic components of high yield and high reliability can be manufactured.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a ceramic electronic component, and more particularly to a method for manufacturing a ceramic electronic component such as a positive temperature coefficient thermistor manufactured by using an electroless Ni plating method.

[0002]

2. Description of the Related Art Generally, an electrode used for a positive temperature coefficient thermistor has good ohmic contact and an inexpensive electrode.
Ni electrodes by electroless plating are often used.

According to the electroless plating method, since Ni plating is formed on the entire surface of the semiconductor ceramic, it is necessary to remove the Ni plating formed on the side surface of the semiconductor ceramic. Normally, the outer peripheral surface of semiconductor porcelain is shaved off by polishing, but in recent years, as the size of positive temperature coefficient thermistor elements etc. has progressed, the element thickness has become thinner, resulting in chipping and cracking during polishing of the outer peripheral surface. There was a problem that there was a problem with sex.

As a method of not polishing the outer peripheral side surface, Ni
There is a method of applying Ni plating after masking with tape or organic material so that plating is not formed on the side surface of semiconductor porcelain, but with this method, if the mask material is left as it is without removing it, The mask material is burned onto the semiconductor porcelain by the heat treatment performed to increase the adhesive strength between the semiconductor porcelain and the Ni plating. Therefore, there is a problem that a mask material peeling step is required before the heat treatment, which requires a long working time.

The present invention has been invented in view of the above problems, and it is possible to manufacture an element such as a positive temperature coefficient thermistor having a high yield and reliability without forming Ni plating on the side surface of a semiconductor ceramic. It is an object to provide a method for manufacturing a ceramic electronic component.

[0006]

In order to achieve the above object, a method of manufacturing a ceramic electronic component according to the present invention is a method of coating a side surface of a cylindrical semiconductor ceramic with paraffin to form electroless Ni.
It is characterized in that Ni-plated electrodes are formed on both planes of the semiconductor porcelain by a plating method, and then heat treatment is performed.

In order to easily prevent Ni plating from being formed on the side surface of the semiconductor porcelain, it is necessary to develop a mask material that can be easily peeled off. Therefore, the present inventor has variously studied the mask material such that the mask material is removed at the same time in the heat treatment step performed to improve the adhesion between the semiconductor ceramic and the Ni electrode after Ni plating, and the peeling step is not required. As a result, they have found that paraffin, which melts and evaporates at low temperature and is harmless to semiconductor porcelain, is useful, and has completed the present invention. Also, paraffin is 5
Since it melts at 0 ° C or higher and hardens at 50 ° C or lower, it has the advantage of good operability.

[0008]

According to the above-mentioned method, the side surface of the cylindrical semiconductor porcelain is coated with paraffin, the Ni-plated electrodes are formed on both planes of the semiconductor porcelain by the electroless Ni plating method, and then the heat treatment is performed. The Ni plating mask material for the paraffin is easily avoided from forming the Ni plating on the side surface of the semiconductor porcelain, and the paraffin is evaporated at the same time during the heat treatment step.
A ceramic electronic component having high yield and high reliability can be manufactured without requiring a special process for removing the paraffin.

[0009]

EXAMPLES Examples of the method for manufacturing a ceramic electronic component according to the present invention will be described below. First, as a raw material for semiconductor porcelain, 100 mol of (Ba _0.9 Sr _0.1 ) TiO _{3 was} mixed with MnO _{2 in an amount} of 0.
05 mol, TiO ₂ 1.0 mol, SiO ₂ 1.0 mol, Nb
0.1 mol of ₂ O ₅ was added and mixed, calcined and then molded,
Main firing at a temperature of 1350 ° C for 2 hours, diameter 12m
A disc-shaped semiconductor porcelain having a thickness of m and a thickness of 0.4 mm was obtained.

Paraffin melted at 70 ° C. is applied to the side surface of this semiconductor porcelain and hardened, and then immersed in a Ni plating pretreatment liquid. Then, electroless Ni plating is performed by immersing the paraffin-coated semiconductor porcelain in a Ni plating solution for about 30 minutes at room temperature to form Ni-plated electrodes on both planes of the semiconductor porcelain, and then at 400 ° C. In order to evaporate the paraffin, the adhesive strength between the Ni plating and the semiconductor porcelain was strengthened. At this time, Ni
The plating thickness was about 2 μm. Then, a silver paste was printed and fired, and the lead wire was soldered.

The yield of the positive temperature coefficient thermistor thus obtained and the yield of the positive temperature coefficient thermistor obtained by the method of removing the Ni plating by polishing the outer peripheral surface of the semiconductor porcelain were investigated 100 each. .. The results are shown in Table 1.

[0012]

[Table 1]

In the conventional method in which the entire surface of the ceramic electronic component is plated with Ni and then the outer peripheral side surface is polished, chips and cracks are generated by polishing, a withstand voltage defect occurs, and the yield is 91%. On the other hand, in the method for manufacturing a ceramic electronic component according to this example, no chipping or cracking occurred,
The yield was 100%, and a remarkable effect was obtained.

In the above embodiments, the method of applying paraffin to the side surface of the semiconductor porcelain and curing it and immersing it in the Ni plating pretreatment liquid is explained. The same effect can be obtained by applying. Also, the case where a Ni-plated electrode is formed on a semiconductor porcelain and heat treatment is applied to evaporate the paraffin is explained.However, after the Ni-plated electrode is formed on the semiconductor porcelain, the paraffin is evaporated at the same time as the firing of the silver paste. The adhesion strength between the Ni plating and the semiconductor porcelain may be strong. Furthermore, when performing electroless Ni plating, the case of immersing in a Ni plating solution at room temperature for about 30 minutes has been described, but it is desirable to change the impregnation time depending on the thickness of the Ni plating and the temperature of the Ni plating solution.

[0015]

As described above in detail, in the method for manufacturing a ceramic electronic component according to the present invention, the side surface of a cylindrical semiconductor ceramic is coated with paraffin and both sides of the semiconductor ceramic are electrolessly plated by electroless Ni plating. Form a Ni-plated electrode on the flat surface,
Since heat treatment is performed after this, it is possible to easily avoid the formation of the Ni plating on the side surface of the semiconductor porcelain by the paraffin that is the Ni plating mask material, and at the same time, the paraffin is evaporated during the heat treatment process. By doing so, it is possible to manufacture a ceramic electronic component with high yield and reliability without requiring a special process for removing the paraffin.

Claims (1)

[Claims] 1. A ceramic which is characterized in that the side surface of a cylindrical semiconductor ceramic is coated with paraffin, Ni plated electrodes are formed on both planes of the semiconductor ceramic by electroless Ni plating, and then heat treatment is performed. Manufacturing method of electronic parts.