JP2001015371A - Chip-type ceramic electronic component and manufacture thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To obtain highly reliable chip-type ceramic electronic components, the ceramic sintered body of which hardly cracks, even when a printed circuit board expands, contracts or bends and stresses are applied to the sintered body after the electronic components are mounted on the board. SOLUTION: A laminated capacitor 1 constituted as a chip-type ceramic electronic component is constituted, in such a way that first and second terminal electrodes 9 and 10 are formed to respectively cover the first and second terminal faces of a ceramic sintered body 2, and the electrodes 9 and 10 have electrode cover sections 9a and 20 reaching the top face 2c, bottom face 2d, and side faces of the sintered body 2. In addition, voids 11 and 12 are respectively formed between the internal surfaces of the cover sections 9a and 10a and the external surface of the sintered body 2.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a chip-type ceramic electronic component such as a multilayer capacitor, and more particularly, to a chip-type ceramic electronic component having terminal electrodes formed so as to cover end faces of a ceramic sintered body. Related to parts.

[0002]

2. Description of the Related Art FIG. 6 is a longitudinal sectional view showing a multilayer capacitor as an example of a conventional chip-type electronic component. In the multilayer capacitor 51, a plurality of internal electrodes 53 to 58 are arranged inside a ceramic sintered body 52 made of dielectric ceramic so as to overlap in a thickness direction via a ceramic layer. The internal electrodes 53, 55, 57 are drawn out to the end face 52 a of the ceramic sintered body 52, and the internal electrodes 5
4, 56, 58 are drawn out to the end face 52b. Terminal electrodes 59 and 60 are formed on the end faces 52a and 52b, respectively.

[0003] Terminal electrodes 59 and 60 are connected to end faces 52a and 52, respectively.
b, but also has electrode covering portions 59a and 60a reaching the upper surface 52c, the lower surface 52d, and both side surfaces. That is, by forming the electrode covering portions 59a and 60a, for example, it is possible to facilitate soldering when mounted on a printed circuit board.

[0004] Further, for chip-type ceramic electronic components such as the multilayer capacitor 51, various chip-type electronic components having terminal electrodes having holes have been proposed in order to increase the mechanical strength against external force (for example, see, for example, Japanese Patent Application Laid-Open No. H11-157556). JP 5
-3132, JP-A-8-107038, JP-A-8-162359, JP-A-9-162604
Issue publication).

In the chip type electronic components described in these prior arts, terminal electrodes are formed by laminating a plurality of layers, and holes are formed in at least one layer, or internal electrodes of a ceramic sintered body. In this case, a glass layer and a terminal electrode are laminated on the end face from which is drawn, and a gap is formed between the glass layer and the terminal electrode on the end face.

[0006]

However, in a conventional chip-type ceramic electronic component, when heat is applied after the printed circuit board is mounted or when the printed circuit board is bent, the ceramic sintered body is subjected to stress caused by these. There was a problem that cracks were generated in the steel. That is, for example, it is assumed that when the multilayer capacitor 51 shown in FIG. 6 is mounted on the printed circuit board from the lower surface side, the printed circuit board is deformed into a concave shape or a convex shape. In this case, since the multilayer capacitor 51 is fixed to the printed circuit board by using the terminal electrodes 59 and 60, the multilayer capacitor 51 is also subjected to a stress such that it becomes concave or convex. As a result, cracks tend to occur in the ceramic sintered body 52.

SUMMARY OF THE INVENTION An object of the present invention is to provide a chip-type ceramic having excellent mechanical strength and reliability, in which even if the printed circuit board is bent after being mounted on the printed circuit board, cracking of the ceramic sintered body is unlikely to occur. To provide electronic components.

[0008]

According to a broad aspect of the present invention, a ceramic sintered body having first and second end faces facing each other and a first and second end face of the ceramic sintered body are connected to each other. And a first and second terminal electrode having an electrode covering portion extending to the upper surface, the lower surface, and both side surfaces. The inner surface of the electrode covering portion of the first and second terminal electrodes and the outer surface of the ceramic sintered body. And a chip-type ceramic electronic component, wherein a void is formed between the two.

Preferably, when the direction connecting the first and second end faces is the length direction, the length of the gap is 10 times the length of the electrode covering portion of the terminal electrode provided with the gap. ~
The range is 90%.

[0010] In a specific aspect of the present invention, there is further provided a plurality of internal electrodes arranged so as to overlap each other via a ceramic layer in the ceramic sintered body, wherein the internal electrodes are formed of a first ceramic sintered body. Alternatively, the multilayer ceramic electronic component is formed by being drawn out to the second end face and electrically connected to the first or second terminal electrode.

According to another broad aspect of the present invention, a step of preparing a ceramic sintered body having opposed first and second end faces, and a step of preparing a ceramic sintered body near the first and second end faces A step of applying an organic material paste scattered by heat at the time of baking terminal electrodes to at least one of an upper surface, a lower surface, and both side surfaces of the ceramic sintered body; and first and second end surfaces of the ceramic sintered body. And a step of applying a conductive paste from the first and second end surfaces to the upper surface, the lower surface and both side surfaces, and coating the organic material paste layer, and baking the conductive paste to form the first and second conductive pastes. Forming a terminal electrode, and scattering the organic material paste during the baking to form a void.

[0012]

DESCRIPTION OF THE PREFERRED EMBODIMENTS Hereinafter, the present invention will be clarified by describing specific embodiments of the present invention with reference to the drawings.

FIG. 1 is a longitudinal sectional view showing a multilayer capacitor as a chip-type ceramic electronic component according to one embodiment of the present invention. The multilayer capacitor 1 has a rectangular parallelepiped ceramic sintered body 2 made of a dielectric ceramic such as a barium titanate-based ceramic. In the ceramic sintered body 2, a plurality of internal electrodes 3 to 8 are arranged so as to overlap in the thickness direction via a ceramic layer.

The internal electrodes 3, 5, 7 are drawn out to the first end face 2 a of the ceramic sintered body 2. Internal electrode 4,
6 and 8 are drawn out to the second end face 2b opposite to the first end face.

The internal electrodes 3 to 8 are made of Ag, Ag-Pd
Alternatively, it can be configured using an appropriate noble metal or base metal such as Ni. Further, the ceramic sintered body 2 having the internal electrodes 3 to 8 can be obtained according to a known method of manufacturing a multilayer capacitor. That is, it can be obtained by printing a conductive paste for forming an internal electrode on a ceramic green sheet, stacking the ceramic green sheets on which the conductive paste is printed, obtaining a laminate, and firing the laminate. .

A first terminal electrode 9 is formed so as to cover the first end face 2a of the ceramic sintered body 2. Further, a second terminal electrode 10 is formed so as to cover the second end face 2b. The terminal electrodes 9 and 10 are coated with a conductive paste.
It is formed by baking. In this embodiment,
Although the terminal electrodes 9 and 10 are constituted by a single layer,
The outer surface of the baked layer of the conductive paste may be plated with another metal material. That is, a Ni plating layer and a Sn plating layer are sequentially formed, and thereby, the solder erosion of the electrode film formed by applying and baking a conductive paste is reduced to Ni.
This may be prevented by a layer, and solderability may be enhanced by a Sn layer.

The first and second terminal electrodes 9 and 10 are
Since the second electrodes 2 are formed so as to cover the second end faces 2 a and 2 b, the internal electrodes 3, 5 and 7 are electrically connected to the first terminal electrode 9, and the internal electrodes 4, 6 and 8 are electrically connected to the second terminal electrode 10. It is connected to the.

The terminal electrodes 9 and 10 are
a and 10a. The electrode covering portions 9a and 10a are formed so as to reach the upper surface 2c, the lower surface 2d, and both side surfaces of the ceramic sintered body 2. Since the electrode covering portions 9a and 10a are formed, surface mounting can be easily performed on the printed circuit board or the like by using the electrode covering portions 9a and 10a.

A feature of the multilayer capacitor 1 of the present embodiment is that voids 11 and 12 are formed between the electrode covering portions 9 a and 10 a and the outer surface of the ceramic sintered body 2. In the present embodiment, the gaps 11 and 12 are formed so as to be wound around the ceramic sintered body 2. That is, the gaps 11 and 12 are formed so as to reach the upper surface 2c, the lower surface 2d, and both side surfaces.

In the multilayer capacitor 1, the gaps 11, 12
Are formed between the electrode covering portions 9 a and 10 a and the outer surface of the ceramic sintered body 2. In other words, void 1
The reference numerals 1 and 12 are provided so that a part of the electrode covering portions 9 a and 10 a does not contact the outer surface of the ceramic sintered body 2. Therefore, the periphery of the gaps 11 and 12 is formed between the outer surface of the ceramic sintered body 2 and the electrode covering portion 9a or the electrode covering portion 10a.
a is surrounded by a.

Since the voids 11 and 12 are formed, the printed circuit board bends when mounted on the printed circuit board, and the stress caused by the bend is caused by the terminal electrode 9, as will be apparent from an experimental example described later. , 10 are effectively prevented from cracking in the ceramic sintered body 2. That is, the conventional multilayer capacitor 5
The cracks generated in the first ceramic sintered body 52 are as follows:
In many cases, this occurred from the inner ends of the electrode covering portions 59a and 60a to the inside of the ceramic sintered body 52. this is,
It is considered that the stress caused by the bending of the printed circuit board is concentrated on the inner ends of the covering portions 59a and 60a of the terminal electrodes 59 and 60.

In the multilayer capacitor 1 of this embodiment, the gap 1
Since the terminals 1 and 12 are provided, even if the terminal electrodes 9 and 10 are subjected to a stress due to the deflection of the printed circuit board, the gaps 11 and 12 cause the terminal electrodes 9 and 10 to be appropriately deformed. It is difficult for stress to concentrate on the electrode covering portions 9a and 10a. Therefore, cracks in the ceramic sintered body 2 caused by the stress concentration can be reliably suppressed.

That is, the gaps 11 and 12 are formed when the printed circuit board or the like expands / contracts or flexes.
It functions to alleviate the concentration of stress applied to the terminal electrodes 9 and 10, thereby suppressing the occurrence of cracks.

Next, based on specific experimental examples, the operation and effect of the gaps 11 and 12 will be clarified, and a method of manufacturing the chip-type ceramic electronic component of this embodiment will be described.
First, there was prepared a ceramic sintered body 2 in which a plurality of internal electrodes were arranged so as to overlap each other with a ceramic layer interposed therebetween, and had first and second end faces 2a and 2b facing each other.

Next, the end faces 2a, 2a of the ceramic sintered body 2
In the vicinity of b, organic material pastes 13 and 14 were applied so as to wind the ceramic sintered body 2. The organic material pastes 13 and 14 are made of a material that can be scattered when the conductive paste forming the terminal electrodes 9 and 10 is baked, for example, a material containing ethyl cellulose, alkyd, and an acrylic resin. However, organic material paste 1
The materials constituting the layers 3 and 14 are not limited to these, and can be formed using an appropriate organic material that is scattered when the conductive paste is baked.

Next, an Ag paste is applied from the end face 2a side of the ceramic sintered body 2, and then A paste is similarly applied from the end face 2b side.
g paste was applied. Thereafter, the conductive paste was baked at a temperature of 600 ° C. to form terminal electrodes 9 and 10.
In this case, the organic material pastes 13 and 14 scatter,
The gaps 11 and 12 shown in FIG. 1 are formed. Thus, length 2.00 mm x width 1.25 mm x thickness 0.85
Thus, a multilayer capacitor 1 having a size of mm was obtained. FIG. 3 shows the appearance of the multilayer capacitor 1.

In manufacturing the multilayer capacitor 1, the number of laminated internal electrodes was 35, and the thickness of the ceramic layer between the internal electrodes was 10 μm. The length A of the electrode covering portions 9a and 10a, that is, the distance from the end surface 2a or the end surface 2b to the inner end of the electrode covering portion 9a or 10a was 0.4 mm. Further, in manufacturing the multilayer capacitor 1, the widths of the organic material pastes 13 and 14 are variously changed so that the gap 1
1, 12, that is, the first and second gaps 11 and 12
The lengths in the direction connecting the end surfaces 2a and 2b were variously changed to obtain multilayer capacitors.

For comparison, the organic material pastes 13, 1
A multilayer capacitor was manufactured in the same manner as described above, except that No. 4 was not applied, that is, the gaps 11 and 12 were not formed.

A deflection test and a shear test were performed on these multilayer capacitors in the following manner. Deflection test: A multilayer capacitor was mounted on an electrode on a 1.6 mm thick glass epoxy substrate by soldering. Thereafter, in the center between the terminal electrodes 9 and 10, the glass epoxy substrate is bent in a convex shape so that the glass epoxy substrate moves upward by 5 mm, and the occurrence rate of cracks in the ceramic sintered body 2 in that case is reduced. evaluated. The number of tests n in the bending test was 100, and the ratio of the number of the multilayer capacitors in which cracks occurred in 100 multilayer capacitors was defined as the crack occurrence rate.

Shear test: After mounting the multilayer capacitor on the same electrode on the glass epoxy board as used in the deflection test by soldering, the shear was applied to the multilayer capacitor from the side surface 2e in a direction parallel to the end surfaces 2a and 2b by 20N. A stress was applied, and it was observed whether or not the multilayer capacitor came off the glass epoxy substrate. A shear test was performed on 100 multilayer capacitors, and the ratio of the number of multilayer capacitors in which breakage occurred was determined, which was defined as a breakage occurrence rate. The results of the deflection test and the shear test are shown in Table 1 below.

[0031]

[Table 1]

As is clear from Table 1, the multilayer capacitor of Sample No. 1 having no voids has a very high crack generation rate of 83% in the deflection test. On the other hand, in the multilayer capacitors of Sample Nos. 2 to 9, since the gaps 11 and 12 are provided, the crack generation rate is extremely low, and particularly, the electrode covering portions 9a and 9 having the length B of the gaps 11 and 12 are provided. The ratio to the length A of 10a is 1
The multilayer capacitors of Sample Nos. 4 to 9 having 0% or more had no crack generation rate.

On the other hand, in the multilayer capacitor of Sample No. 9 in which the lengths of the gaps 11 and 12 were relatively long, the breakage rate in the shear test was 12%. Therefore, from the results in Table 1, by setting the length of the gaps 11 and 12 to be in the range of 10 to 90% of the length of the electrode covering portion provided with the gap, the bending strength can be improved and the mounting can be performed. It can be seen that the strength can be increased.

FIGS. 4 and 5 are views for explaining a modified example of the gap. As shown in the partially cutaway sectional view in FIG.
A plurality of voids 11a to 11c may be formed between the electrode covering portion 9a and the outer surface of the ceramic sintered body 2. In this case, the gaps 11 a to 11 c are formed so as to be wound around the ceramic sintered body 2, similarly to the gap 11.

Although the gaps 11 and 12 are formed so as to be wound around the outer periphery of the ceramic sintered body 2, the gaps 11 and 12 may be formed in at least one surface of the electrode covering portion.
Further, a plurality of divided voids may be formed on the upper surface 2c, the lower surface 2d, and the side surface 2e. For example, FIG.
As shown in FIG. 3, a plurality of organic material pastes 13a to 13f and 14a to 14f are formed on the upper surface 2c and the side surface 2e,
A plurality of cavities may be formed by scattering the organic material pastes 13a to 13f and 14a to 14f at the time of baking the conductive paste. In FIG. 5A, the organic material paste formed on the lower surface and the other side surface is not shown.

As described above, a plurality of voids 11d to 11h may be formed in the folded portion 9a of the terminal electrode 9, as shown in FIG. As is clear from FIGS. 4 and 5, as long as the gap is provided between the inner surface of the electrode covering portion and the outer surface of the ceramic sintered body, the number of voids and the planar shape are not particularly limited.

In the above embodiment, the multilayer capacitor 1 in which the internal electrodes 3 to 8 are formed in the ceramic sintered body 2 has been described. However, the present invention relates to a multilayer varistor or a multilayer thermistor having a plurality of internal electrodes. Can also be applied.
Further, the chip-type ceramic electronic component according to the present invention,
The present invention can be applied to a ceramic electronic component having no internal electrode. That is, a chip-type ceramic capacitor in which first and second terminal electrodes having electrode covering portions are formed on both end surfaces of a ceramic sintered body made of dielectric ceramic, and first and second terminal electrodes on both end surfaces of an insulating ceramic. The present invention can also be applied to a chip-type ceramic resistance element formed by forming the terminal electrode having an electrode covering portion.

[0038]

In the chip-type ceramic electronic component according to the present invention, a gap is formed between the inner surface of the electrode covering portion of the first and second terminal electrodes and the outer surface of the ceramic sintered body. , The terminal electrode is appropriately deformed and the stress concentration between the electrode covering portion and the outer surface of the ceramic sintered body is reduced. In other words, when mounted on a printed circuit board, the thermal expansion of the printed circuit board
Concentration of the stress caused by shrinkage or bending on the covered portion is effectively suppressed. Therefore, even when the printed circuit board or the like expands and contracts or bends due to an external force, a temperature change, or the like, it is possible to suppress the occurrence of cracks in the chip-type ceramic electronic component. The strength can be improved, and the reliability of the chip-type ceramic electronic component can be improved.

Further, when the length of the gap is in the range of 10 to 90% of the length of the electrode covering portion of the terminal electrode provided with the gap, the generation of the crack can be suppressed more effectively. In addition, the mounting strength of the chip-type ceramic electronic component on a printed circuit board or the like does not easily decrease.

A plurality of internal electrodes are arranged so as to overlap each other via the ceramic layer in the ceramic sintered body, and the internal electrodes are respectively drawn to the first and second end faces to be connected to the first and second terminal electrodes. Electrically connected,
Thus, when a multilayer ceramic electronic component is configured, stress concentration is likely to occur between the tip of the internal electrode and the inner end of the electrode covering portion of the terminal electrode. However, according to the present invention, the presence of the above-mentioned voids alleviates stress concentration, and therefore, it is possible to provide a multilayer ceramic electronic component which is less likely to crack and has excellent reliability.

In the method for manufacturing a chip-type ceramic electronic component according to the present invention, heat generated when terminal electrodes are baked on at least one of the upper surface, the lower surface, and both side surfaces near the first and second end surfaces of the ceramic sintered body. The organic material paste is scattered, and the conductive paste is applied to form a terminal electrode. When the conductive paste is applied and baked, the organic material paste is scattered to form voids. Therefore, the chip-type ceramic electronic component according to the present invention can be easily provided only by adding the step of applying the organic material paste in the conventional method of manufacturing the chip-type ceramic electronic component.

[Brief description of the drawings]

FIG. 1 is a longitudinal sectional view showing a multilayer capacitor as a chip-type ceramic electronic component according to one embodiment of the present invention.

FIG. 2 is a perspective view showing a state in which an organic material paste is applied to the outer surface of the ceramic sintered body in obtaining the multilayer capacitor of the embodiment shown in FIG.

FIG. 3 is a perspective view showing the appearance of the multilayer capacitor of the embodiment shown in FIG. 1;

FIG. 4 is a partially cutaway longitudinal sectional view of a multilayer capacitor for explaining a modification of a gap.

FIGS. 5A and 5B are diagrams for explaining other modified examples of the air gap, and FIG. 5A is a perspective view showing a ceramic sintered body to which an organic material paste is applied;
(B) is a partially cutaway plan view of the obtained multilayer capacitor.

FIG. 6 is a longitudinal sectional view showing a conventional multilayer capacitor.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Multilayer capacitor 2 ... Ceramic sintered body 2a, 2b ... 1st, 2nd end surface 2c ... Upper surface 2d ... Lower surface 2e ... Side surface 3-8 ... Internal electrode 9, 10 ... 1st, 2nd terminal electrode 9a, 10a ... electrode suffered portion 9a _1, 10a ₁ ... inner end 11, 12 ... gap 11 a to 11 c ... gap 11d to 11h ... gap 13 ... organic material paste 13a to 13f, 14a to 14f ... organic material paste

Claims (4)

[Claims] 1. A ceramic sintered body having first and second end faces facing each other, and an electrode covering part covering the first and second end faces of the ceramic sintered body and reaching to an upper surface, a lower surface, and both side surfaces. And a first and a second terminal electrode having: a gap formed between an inner surface of the electrode covering portion of the first and second terminal electrodes and an outer surface of the ceramic sintered body. Chip-type ceramic electronic components. 2. When the direction connecting the first and second end faces is a length direction, the length of the gap is 10 to 10 of the length of the electrode covering portion of the terminal electrode provided with the gap. The chip-type ceramic electronic component according to claim 1, wherein the range is 90%. 3. The device according to claim 1, further comprising a plurality of internal electrodes arranged so as to overlap each other via a ceramic layer in the ceramic sintered body, wherein the internal electrodes are drawn out to a first or second end face of the ceramic sintered body. The chip-type ceramic electronic component according to claim 1, wherein the chip-type ceramic electronic component is electrically connected to the first or second terminal electrode to form a multilayer ceramic electronic component. 4. A step of preparing a ceramic sintered body having first and second end faces facing each other, and an upper surface of the ceramic sintered body near the first and second end faces of the ceramic sintered body. A step of applying an organic material paste scattered by heat at the time of baking the terminal electrode to at least one of the lower surface and both side surfaces, and from the first, second, and first and second end surfaces of the ceramic sintered body. A step of applying a conductive paste so as to reach the upper surface, the lower surface and both side surfaces, and to cover the organic material paste layer; and baking the conductive paste to form first and second terminal electrodes, Forming a void by scattering the organic material paste at the time of baking.