JP3000825B2 - Ceramic electronic components - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic electronic component.

[0002]

2. Description of the Related Art A multilayer ceramic capacitor as an example of a ceramic electronic component will be described. FIG. 2 is a sectional view of the multilayer ceramic capacitor 1. To explain the structure of this multilayer ceramic capacitor, first,
A ceramic slurry to be the dielectric ceramic 2 is prepared, and a doctor blade is used by using the ceramic slurry.
A dielectric ceramic green sheet is formed by a printing method or the like, and a conductive paste serving as the internal electrode 3 is applied to one surface of the sheet by a screen printing method or the like. A plurality of ceramic green sheets on which the conductive paste is formed are laminated, thermocompressed, cut into an appropriate shape, and fired so that the side from which the conductive paste is drawn out is alternated. . At this time, a laminated sintered body in which the internal electrodes 3 are formed between the dielectric ceramics 2 is obtained. External electrodes 4 are provided at both ends of the multilayer ceramic capacitor 1 so as to be electrically connected to the internal electrodes 3. FIG. 3 shows a general method of using the multilayer ceramic capacitor 1, in which the multilayer ceramic capacitor 1 is fixed to a printed circuit board 5 with solder 6.

[0003]

As shown in FIG. 3, since the multilayer ceramic capacitor 1 is used by being fixed to the printed circuit board 5, when the printed circuit board 5 is bent, the multilayer ceramic capacitor 1 affects the multilayer ceramic capacitor 1, and sometimes it is affected. External electrode 4
A crack 7a may be generated in the vicinity. In addition, when the thermal shock test is performed, cracks 7b may be generated from the end face toward the inside. When the printed circuit board 5 is curved,
A metal paste containing lead borosilicate glass is a good material for the external electrode 4 with respect to the generated bending stress, but cracks tend to occur in a thermal shock test. As a material of the external electrode 4 having good thermal shock resistance, there is a metal paste containing zinc borosilicate glass. However, when the printed board 5 is bent, cracks are easily generated due to bending stress generated. As described above, if it is good for the thermal shock test, cracks occur due to bending stress, and if it is good for bending stress,
Cracks occur in the thermal shock test, and no external electrode material satisfies both characteristics.

An object of the present invention is to provide a ceramic electronic component formed of an external electrode material having a bending stress property against a thermal shock test, a bending of a printed board, and the like.

[0005]

That is, the present invention relates to an external electrode of a ceramic electronic component, wherein the external electrode has one or more electrodes.
Layer contains zinc borosilicate glass which is strong against thermal shock
Metal baking layer that strength in the second layer is the bending stress of the upper layer
Metal baking layer containing lead borosilicate glass have, their
The third layer on the surface of is composed of a plating layer .

[0006]

[0007]

[0008]

[Function] With the above configuration, thermal shock test and printed circuit board
In bending test of electronic components to apply bending stress to electronic components
No cracks occur.

[0009]

FIG. 1 is a sectional view of a multilayer ceramic capacitor according to the present invention. Here, the structure of the multilayer ceramic capacitor will be described.
Internal electrodes 3 are interposed between a plurality of layers of dielectric ceramics 2 so as to be alternately led out to the end faces to form a laminate, and external electrodes 4 electrically connected to the internal electrodes 3 are formed at both ends. I have. In the present invention, the external electrode 4 has a thermal shock resistance.
Baking containing zinc borosilicate glass resistant to heat
Contains layer 4a and lead borosilicate glass that is strong in bending stress
Metal baking layer 4b.

(Example 1) Silver paste containing 4 wt% of zinc borosilicate glass in the paste solid content on the end face of the laminate.
The strike was applied and dried. In the upper layer, a silver paste containing 4 wt% of lead borosilicate glass in the paste solid content was added.
The coating was large and dried so as not to coincide with both ends of the layer, that is, to completely cover the silver paste of the first layer. Thereafter, the resultant was held at 700 ° C. for 5 minutes and baked to form an external electrode. Furthermore, a Ni layer, Sn
A layer was formed.

(Example 2) A silver paste containing zinc borosilicate glass at 4% by weight of paste solid content on the end face of the laminate.
A strike was applied, held at 700 ° C. for 5 minutes, and baked. In the upper layer, lead borosilicate glass is applied in a paste solid content of 4 watts.
The silver paste containing t% was applied in a large size so that both ends of the first layer did not coincide with each other, that is, completely covered the silver paste of the first layer, and baked at 700 ° C. for 5 minutes. Further, a Ni layer and a Sn layer were formed on the surface by electrolytic plating.

Comparative Example 1 A silver paste containing zinc borosilicate glass at 4 wt% in paste solids on the end face of the laminate.
A strike was applied. Thereafter, the resultant was held at 700 ° C. for 5 minutes and baked to form an external electrode. A Ni layer and a Sn layer were formed on the surface by electrolytic plating.

Comparative Example 2 A silver paste containing lead borosilicate glass in a paste solid content of 4% by weight was applied to the end face of the laminate. Thereafter, the resultant was held at 700 ° C. for 5 minutes and baked to form an external electrode. The surface is electrolytically plated with N
An i layer and a Sn layer were formed.

(Comparative Example 3) The silver paste used in Example 2 was applied to the end face of the laminate in the reverse order of formation, that is, lead borosilicate glass was used as the first layer in a paste solid content of 4 wt%. %
A silver paste containing zinc borosilicate glass as a second layer in the second layer and containing 4 wt% of the paste solid content was formed under the same conditions as the other conditions.

(Comparative Example 4) In the same manner as in Example 2, the same size as that of Example 2
A silver baking layer was formed, and a Ni layer and a Sn layer were formed on the surface by electrolytic plating.

Using the multilayer ceramic capacitor thus manufactured, a thermal shock test and a bending stress test by bending the substrate were performed. The thermal shock test method is based on the sample obtained in the present invention as 1
Each of the samples was immersed in molten solder at 325 ° C. (ΔT = 300 ° C.) for 2 seconds. A good product has no cracks in the multilayer ceramic capacitor. In the bending stress test, 30 samples obtained in the present invention were used and fixed to a 1.6 mm thick glass epoxy printed board with solder, and the board was bent to the side without the multilayer ceramic capacitor. The amount of deflection at which a crack occurred in the capacitor was measured. Table 1 shows the results of the thermal shock test and the bending stress test based on the substrate curvature. The numerical value of the bending stress test result is an average value of 30 samples.

[0017]

[Table 1]

Although the embodiment has been described using a multilayer ceramic capacitor, the present invention can be applied to other ceramic electronic parts having external electrodes. Further, although silver paste is used for the external electrode, it may be applied to a conductive paste which does not change its composition by reacting with zinc borosilicate glass or lead borosilicate glass. Further, as shown in the embodiment, a metal layer such as Sn or Ni may be covered on the surface of the external electrode by plating or the like to form a multilayer.

[0019]

By using the external electrodes of the ceramic electronic component of the present invention, cracks do not occur in a thermal shock test or a bending stress test for substrate bending. Therefore, the non-defective rate of the entire ceramic electronic component can be improved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor in the present embodiment.

FIG. 2 is a sectional view of a conventional multilayer ceramic capacitor.

FIG. 3 is a side view showing a state in which a conventional multilayer ceramic capacitor is fixed to a printed circuit board.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 Multilayer ceramic capacitor 2 Dielectric ceramic 3 Internal electrode 4a External electrode consisting of a metal baking layer containing zinc borosilicate glass 4b External electrode consisting of a metal baking layer containing lead borosilicate glass

Claims (1)

(57) [Claims] 1. An external electrode of a ceramic electronic component,
The first layer of the external electrode is zinc borosilicate which is strong in thermal shock resistance
A metal baking layer containing a base glass, a second baking layer above the baking layer, a metal baking layer containing a lead borosilicate glass having high bending stress, and a third layer on the surface thereof being a plating layer. A ceramic electronic component.