JP2000353636A - Laminated ceramic part - Google Patents

Abstract

PROBLEM TO BE SOLVED: To form a laminated ceramic part which is improve in the bending resistance strength against deflection of a mounting substrate. SOLUTION: This laminated ceramic part includes a laminate 15 of invalid layers 10 and inner electrode layers 11 and 13 alternately stacked thereon, and a pair of external electrode 16 formed on the exposed both end faces of the inner electrode layers 11 and 13 of the laminate 15 and at least on lower surfaces thereof adjacent to the both end faces. The thickness of the invalid layers 10 sandwiched by the lower surface of the external electrode 16 of the laminate 15 and by the inner electrode layers 11 is set to 1/10 or of the thickness of the laminate 15 or smaller.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a multilayer ceramic component used for various electronic devices.

[0002]

2. Description of the Related Art A conventional multilayer ceramic component has been configured as shown in FIG. That is, invalid layers 1 and 2 made of a ceramic material having a thickness of 100 μm or more are provided on the upper and lower layers, and effective layers 3 made of the same ceramic material and internal electrode layers 4 are alternately laminated between the invalid layers 1 and 2. The body 5 is constituted, and the internal electrode layer 4 is electrically connected to the internal electrode layer 4 at both end surfaces thereof, the upper and lower surfaces adjacent to the both end surfaces, and a part of the front and back surfaces. The external electrode 6 was provided.

[0003]

In recent years, in multilayer ceramic parts, the bending strength due to the bending of the mounting board has been
This is an important characteristic in assuring reliability during and after mounting on a mounting board. In particular, as the circuit density increases, the circuit mounting speed increases, and the usage environment changes, there is a demand for further improvement in bending resistance due to the bending of the mounting substrate of the multilayer ceramic component.

[0004] Against this background, the multilayer ceramic component having the above-described conventional configuration has insufficient bending strength because the thickness of the upper and lower ineffective layers 1 and 2 is 100 µm or more. Was.

SUMMARY OF THE INVENTION An object of the present invention is to provide a laminated ceramic component having excellent bending strength by eliminating the above-mentioned conventional disadvantages.

[0006]

In order to solve the above-mentioned problems, a laminated ceramic component according to the present invention is provided with an ineffective layer made of a ceramic material at least as a lowermost layer, and an effective layer made of a ceramic material and an internal layer formed on the ineffective layer. A laminate in which electrode layers are alternately laminated; and an external electrode formed on at least a part of a lower surface adjacent to both exposed end faces of the internal electrode layer of the laminate and the both end faces. The thickness of the ineffective layer between the lower surface portion and the internal electrode layer facing the lower surface portion is set to be 1/10 or less of the thickness of the laminate.

With this configuration, it is possible to improve the bending strength due to the bending of the mounting board.

[0008]

According to the first aspect of the present invention, at least the lowermost layer is provided with an ineffective layer made of a ceramic material, and an effective layer made of a ceramic material and an internal electrode layer are alternately formed on the ineffective layer. And an external electrode formed on at least a part of a lower surface adjacent to both the exposed end surfaces of the internal electrode layer of the laminate, and a lower surface portion and a lower surface portion of the external electrode. The thickness of the ineffective layer between the internal electrode layer and the internal electrode layer facing the
The configuration is set to 10 or less, and the bending strength due to the bending of the mounting board can be improved.

According to a second aspect of the present invention, an ineffective layer having a thickness of 1/10 or less of the thickness of the laminate is provided also on the uppermost layer of the laminate, and a part of the upper surface of the uppermost ineffective layer is also provided with an external layer. This is a configuration in which electrodes are provided, so that there is no directionality during mounting.

According to a third aspect of the present invention, there is provided a laminate in which an ineffective layer made of a ceramic material is provided at least as a lowermost layer, and an effective layer made of a ceramic material and an internal electrode layer are alternately stacked on the ineffective layer. A lower surface of an external electrode formed on a lower surface of the laminated body of the ineffective layer, comprising: an exposed both end surface of the internal electrode layer of the laminate and an external electrode formed on at least a part of a lower surface adjacent to the both end surfaces. A reinforcing electrode is provided in the ineffective layer facing the portion, and the thickness of the ineffective layer between the reinforcing electrode and the lower surface portion of the external electrode is reduced to 1/10 of the thickness of the laminate.
With the following configuration, the bending strength can be improved even when a thick ineffective layer is used.

According to a fourth aspect of the present invention, an ineffective layer provided with a reinforcing electrode is also provided on the uppermost layer of the laminate, and an upper surface portion formed on the uppermost inactive layer of the external electrode and the reinforcing electrode. In this case, the thickness of the ineffective layer is 1/10 or less of the thickness of the laminate, and the directionality during mounting can be eliminated.

According to a fifth aspect of the present invention, the thickness of the ineffective layer between the lower surface or upper surface of the external electrode and the internal electrode layer or the reinforcing electrode is set to 80 μm or less, and the bending strength is improved. The specific thickness dimension of the ineffective layer to be made is clarified.

According to a sixth aspect of the present invention, the reinforcing electrode is electrically connected to the external electrode, so that the stray capacitance due to the reinforcing electrode can be eliminated and the characteristics can be stabilized.

According to the present invention, the reinforcing electrode is electrically separated from the external electrode, so that the reinforcing electrode can be formed roughly.

The invention according to claim 8 is a structure in which two or more reinforcing electrodes are provided in the inactive layer, and the bending resistance in all the thickness directions of the thick inactive layer is excellent. be able to.

According to a ninth aspect of the present invention, the outermost layer of the internal electrode layer of the third or fourth aspect is formed so as not to overlap in the thickness direction with a reinforcing electrode provided at a portion of the external electrode connected to the opposing internal electrode. Thus, the bending strength can be improved, and the withstand voltage and the starting voltage of creeping discharge generated between external electrodes on the surface can be increased particularly in a capacitor used for medium to high pressure applications.

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

Embodiment 1 A multilayer ceramic capacitor as a representative example of a multilayer ceramic component according to Embodiment 1 of the present invention will be described with reference to FIG. In FIG. 1, reference numeral 10 denotes an ineffective layer made of a lowermost ceramic material;
Reference numeral 1 denotes an internal electrode layer formed on the ineffective layer 10 and exposed on one end surface side, and 12 denotes an internal electrode layer 11
An effective layer 13 made of a ceramic material is formed on the effective layer 12, an internal electrode layer formed on the effective layer 12 so as to be exposed to the other end surface side different from the internal electrode layer 11, and 14 is an internal electrode layer 11 , An effective layer 12 and an internal electrode layer 13 are alternately stacked in a required number of layers.
A laminate 16 composed of the internal electrode layers 11 and 13 and the effective layer 12 is provided with both end faces of the laminate 15 and external parts formed on a part of the upper, lower, front, and rear surfaces adjacent to the both end faces. Electrodes.

In the above configuration, the ineffective layers 10 and 14 have a thickness of 1/10 or less of the thickness of the laminate 15. Specifically, it is formed to a size of about 80 μm or less, and is formed as thin ineffective layers 10 and 14. Even when a bending stress is applied to a mounting board or after mounting, the internal electrode layer 11 or 13 is protected by the viscoelasticity, and cracking and chipping can be prevented.

Embodiment 2 Next, a multilayer ceramic capacitor as a representative example of a multilayer ceramic component according to Embodiment 2 of the present invention will be described with reference to FIG. In FIG. 2, reference numeral 10 denotes a thick ineffective layer made of a lowermost ceramic material, 11 denotes an internal electrode layer formed on the ineffective layer 10 and exposed on one end surface side, and 12 denotes an inner electrode layer formed on the inner electrode layer 11. An effective layer of a formed ceramic material,
Reference numeral 13 denotes an internal electrode layer formed on the effective layer 12 so as to be exposed on the other end surface side different from the internal electrode layer 11.
4 is the internal electrode layer 11, the effective layer 12, the internal electrode layer 13
Are formed on the upper surface in which the ineffective layers 10 and 15 are formed of the lowermost ceramic material.
14, a laminate composed of the internal electrode layers 11, 13 and the effective layer 12, 16 is an external electrode formed on both end faces of the laminate 15 and upper and lower surfaces adjacent to the both end faces and a part of the front and rear faces; Is a reinforcing electrode formed so as to be an ineffective layer having a thickness of 1/10 or less of the thickness of the laminated body 15 at a position facing at least portions of the ineffective layers 10 and 14 formed on the upper and lower surfaces of the external electrode 16. It is.

A method of manufacturing the multilayer ceramic capacitor having the above configuration will be described. In laminating a plurality of ceramic green sheets formed of a slurry containing barium titanate as a main component to a predetermined thickness to form the ineffective layer 10, a thickness between the lower surface and the lower surface in the laminating process is 80 μm or less. A reinforcing electrode 17 containing silver or nickel as a main component is formed by printing, and an internal electrode layer 11 also containing silver or nickel as a main component is printed on the ineffective layer 10. An effective layer 12 made of a green sheet is laminated, and an internal electrode layer 13 is formed thereon.
Is printed, then the steps of printing the internal electrode layer 11, laminating the ceramic green sheets of the effective layer 12, and printing the internal electrode layer 13 are repeated a plurality of times.
The ineffective layer 14 on which the reinforcing electrode 17 is printed is laminated and fired at the following positions, and the internal electrode layers 11 and 13 and the reinforcing electrode 17 are exposed at both end surfaces of the sintered laminate 15. External electrodes 16 made of silver or the like were formed on the upper and lower surfaces and the front and rear surfaces adjacent to both end surfaces, and nickel plating and Sn-Pb plating were performed on silver as the external electrodes 16 to obtain a multilayer ceramic capacitor.

This laminated ceramic capacitor has a length of 3.2 mm, a width of 1.6 mm, and a thickness of 0.85 mm.
mm, the length of the laminate 15 excluding the external electrodes 16 is 3.1 mm in the length direction, 1.5 mm in the width direction, 0.81 mm in the thickness direction, and has a capacitance of 0.1 μF, Tan δ 1.5%, and insulation resistance. 1x
It was 10 ¹¹ Ω.

As a comparative example, the thickness of the inactive layer having the same shape, the same capacitance, Tan δ, and insulation resistance as those of the second embodiment and having no reinforcing electrode is set to 100 μm, 120 μm,
A multilayer ceramic capacitor having a size of 140 μm was prepared.

Using these multilayer ceramic capacitors of the present invention and the comparative example, the results of measuring the bending strength due to the bending of the mounting board are shown in Table 1.

[0025]

[Table 1]

The bending strength is determined by mounting a multilayer ceramic capacitor on a mounting board having a thickness of 1.6 mm, and gradually bending the mounting board by 0.2 mm, thereby lowering the capacitance of the multilayer ceramic capacitor. The amount of deflection immediately before was expressed as bending resistance due to deflection of the mounting board.

As is clear from Table 1, when the thickness of the inactive layers 10 and 14 between the external electrode 16 and the reinforcing electrode 17 is set to 80 μm or less, the bending resistance due to the bending of the mounting board is remarkably improved. You can see that

When the invalid layers 10 and 14 are formed to be thick, as shown in FIG. 3, a plurality of reinforcing electrodes are provided on the internal portions of the invalid layers 10 and 14 facing the lower surface or upper surface of the external electrode 16. By forming 17, the bending strength due to the bending of the mounting board can be further improved. Also in this case, the thickness of the inactive layers 10 and 14 between the external electrode 16 and the reinforcing electrode 17 and between the reinforcing electrodes 17 is 80.
The condition is that the thickness be equal to or less than μm.

In FIGS. 2 and 3, the reinforcing electrode 17 is electrically connected to the external electrode 16, and the stray capacitance due to the reinforcing electrode 17 is eliminated to stabilize the characteristics. As shown in FIG. 4, the reinforcing electrode 17 is separated from the external electrode 16, that is, even if the reinforcing electrode 17 is not formed up to the end face on which the external electrode 16 is formed, the reinforcing electrode 17 and the external electrode 16 can be separated. Invalid layer 10,
By setting the thickness of 14 to 80 μm or less, the bending resistance due to the bending of the mounting substrate can be improved, and the reinforcing electrodes 17 can be formed roughly, which is advantageous in terms of productivity.

As shown in FIGS. 5 and 6, the outermost layer 11a of the internal electrode layer 11 is provided at the portion of the external electrode 16a connected to the internal electrode 13 facing the capacitor, particularly in a capacitor used for medium and high voltage applications. The outer electrode 13a of the internal electrode layer 13 is formed so as not to overlap with the provided reinforcing electrode 17a in the thickness direction.
It is desirable to form the reinforcing electrode 17b provided in the portion 6b so as not to overlap in the thickness direction. Thereby, the bending strength can be improved, and the withstand voltage and the starting voltage of creeping discharge generated between the external electrodes on the surface can be increased.

More specifically, for example, the inner electrode layer 13 is formed so as not to overlap in the thickness direction with the reinforcing electrode 17b provided at the portion of the outer electrode 16b connected to the inner electrode 11 opposed to the outermost layer 13a. 13 outermost layer 13a
The withstand voltage and the starting voltage of creeping discharge can be increased as the distance between the electrode and the reinforcing electrode 17b is increased. However, when the length of the outermost layer 13a is less than half the total length of the laminate, the effect is reduced and the capacitance is also reduced.
The length of 3a is preferably about half of the total length of the laminate.

Also, for example, the outermost layer 13 of the internal electrode layer 13
By increasing the distance between the reinforcing electrode 17b provided at the portion of the external electrode 16b connected to the internal electrode 11 facing the internal electrode 11a, the number of layers of the reinforcing electrode 17b can be increased as shown in FIGS. Therefore, the bending strength can be further improved. In FIG. 6, unlike FIG. 5, the reinforcing electrodes 17a and 17b are formed in a state separated from the external electrodes 16a and 16b.
Even if the distance between the outermost layer 13a and the reinforcing electrode 17b is closer than in the case of FIG. 5, the withstand voltage and the starting voltage of the creeping discharge can be increased. Further, in FIGS. 5 and 6, the outermost layers 11a and 13a of the internal electrode layers 11 and 13 are formed so as to be connected to different external electrodes, but may be formed so as to be connected to the same external electrode.

In each of the above-described embodiments, the structure in which the invalid layers 10 and 14 are provided on the upper and lower surfaces has been described. However, this is to eliminate the vertical direction during mounting. If there is no problem, a configuration in which only the ineffective layer 10 is provided only on the lower surface may be adopted.

Further, in the above embodiment, the multilayer ceramic capacitor has been described as an example. However, other multilayer ceramic components such as a multilayer varistor and a multilayer thermistor may have excellent bending strength by adopting a similar configuration. It can be.

[0035]

As described above, since the multilayer ceramic component of the present invention is constructed, the bending resistance due to the bending of the mounting board is improved. In other words, those that are easily cracked by bending in the inactive layer near the end of the lower surface portion of the external electrode,
The fragile ineffective layer is reinforced by the viscoelasticity of the internal electrode layer or the reinforcing electrode, whereby cracking due to bending can be prevented, and high reliability can be achieved.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view of a multilayer ceramic component according to an embodiment of the present invention.

FIG. 2 is a sectional view of another embodiment.

FIG. 3 is a sectional view showing another example.

FIG. 4 is a sectional view showing still another example.

FIG. 5 is a sectional view showing still another example.

FIG. 6 is a sectional view showing still another example.

FIG. 7 is a sectional view showing a conventional multilayer ceramic component.

[Explanation of symbols]

 10, 14 invalid layer 11, 13 internal electrode layer 11a, 13a outermost layer 12 effective layer 15 laminated body 16, 16a, 16b external electrode 17, 17a, 17b reinforcing electrode

Continued on front page F term (reference) 5E001 AB03 AC07 AD00 AF06 AG00 5E082 AB03 BC31 EE04 EE11 EE35 FG26 FG51 FG54 GG10 GG26 GG28 JJ03 JJ15 JJ23 MM24 PP09 5E346 AA33 CC16 EE32 HH11 HH21

Claims (9)

[Claims] 1. A laminate in which an ineffective layer made of a ceramic material is provided at least as a lowermost layer, and an effective layer made of a ceramic material and an internal electrode layer are alternately stacked on the ineffective layer.
An external electrode formed on at least a part of a lower surface adjacent to the both end surfaces of the internal electrode layer of the laminate, and an internal electrode layer facing the lower surface portion and the lower surface portion of the external electrode; Wherein the thickness of the ineffective layer is 1/10 or less of the thickness of the laminate. 2. The method according to claim 1, wherein the uppermost layer of the laminate has a thickness of 1 / th of the thickness of the laminate.
2. The multilayer ceramic component according to claim 1, wherein an ineffective layer having a thickness of 10 or less is provided, and an external electrode is also provided on a part of an upper surface of the uppermost ineffective layer. 3. A laminate in which an ineffective layer made of a ceramic material is provided at least as a lowermost layer, and an effective layer made of a ceramic material and internal electrode layers are alternately stacked on the ineffective layer;
A lower surface of an external electrode formed on a lower surface of the laminated body of the ineffective layer, comprising: an exposed both end surface of the internal electrode layer of the laminate and an external electrode formed on at least a part of a lower surface adjacent to the both end surfaces. A laminated ceramic component having a reinforcing electrode provided in an ineffective layer facing the portion, wherein the thickness of the ineffective layer between the reinforcing electrode and the lower surface of the external electrode is 1/10 or less of the thickness of the laminate. 4. An ineffective layer having a reinforcing electrode provided also on the uppermost layer of the laminate, and the thickness of the inactive layer between the upper surface portion formed on the uppermost inactive layer of the external electrode and the reinforcing electrode is laminated. The multilayer ceramic component according to claim 3, wherein the thickness is 1/10 or less of the thickness of the body. 5. The thickness of an ineffective layer between a lower surface portion or an upper surface portion of an external electrode and an internal electrode layer or a reinforcing electrode is set to 80 μm.
The multilayer ceramic component according to any one of claims 1 to 4, wherein m is equal to or less than m. 6. The multilayer ceramic component according to claim 3, wherein the reinforcing electrode is electrically connected to an external electrode. 7. The multilayer ceramic component according to claim 3, wherein the reinforcing electrode is electrically separated from the external electrode. 8. The multilayer ceramic component according to claim 3, wherein two or more reinforcing electrodes are provided in the ineffective layer. 9. The multilayer ceramic component according to claim 3, wherein the outermost layer of the internal electrode layers is formed so as not to overlap in the thickness direction with a reinforcing electrode provided at a portion of the external electrode connected to the internal electrode facing the internal electrode layer.