JP2004235377A - Ceramic electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic electronic component whose impact resistivity is excellent. <P>SOLUTION: This ceramic electronic component 10 is constituted of a component main body 1 constituted of ceramics formed with an internal conductor and a plurality of external electrodes 5 and 6 formed across the edge faces and main faces of the component main body 1. In this case, the external electrodes 5 and 6 are formed so that the thickness of the ridges of the edge faces and main faces of the component main body 1 can be made thick. <P>COPYRIGHT: (C)2004,JPO&NCIPI

Description

【００５６】
表に示すように、外部電極５、６が平坦部５ａ、６ａ及び凸部５ｂ、６ｂからなる本実施例（試料番号２〜６、８〜１１）は、ｒｔ／ｒ１≧０．２５の範囲に入るようにした場合も、Ｗ方向の寸法が１．４７ｍｍ以下であるとともに、２ｍの高さよりコンクリート板上に落下させた場合のクラック３８の発生率は５％以下となった。特に、ｍａ／Ｔ比が０．３以上であり、且つｎｂ／ｎａ比が１．５以上である場合（試料番号３〜５、９〜１１）は、Ｗ方向の寸法が１．４ｍｍ以下であるとともに、クラック３８の発生率は０％以下となった。
【００５７】
これに対し、外部電極５、６に凸部５ｂ、６ｂを形成しない比較例（試料番号７）は、ｒｔ／ｒ１＜０．２５となり、また２ｍの高さよりコンクリート板上に落下させた場合、クラック３８が４０％発生した。
【００５８】
一方、外部電極５、６に凹部５ａ、６ａを形成しない比較例（試料番号１）は、ｒｔ／ｒ１≧０．２５の範囲に入るようにした場合、Ｗ方向の寸法が１．４７ｍｍより大きくなった。
【００５９】
これらの結果から、本発明の多連型コンデンサ１０は、外部電極５、６は、部品本体１の端面の略中央に形成された平坦部５ａ、６ａと、平坦部５ａ、６ａに隣接するとともに、主面にまたがる凸部５ｂ、６ｂとからなるため、Ｗ方向の寸法を大きくせずに、実装状態において、落下などによる衝撃が加わっても、クラック３８の発生を低減できることがわかった。
【００６０】
【発明の効果】
本発明のセラミック電子部品によれは、部品本体の端面と主面との稜線部分の外部電極の厚みを厚くしたため、耐衝撃性に優れている。
【００６１】
また、部品本体の端面の略中央に外部電極の平坦部が形成されており、外部電極全体の厚みを大きくせずに済むため、小型大容量化、有機バインダ樹脂の除去が容易に行われる、接合材のはい上がる高さを低くするなどの効果がある。
【図面の簡単な説明】
【図１】本発明の多連型コンデンサを示す図であり、（ａ）は外観斜視図、（ｂ）はＸ−Ｘ線断面図である。
【図２】図１の多連型コンデンサを配線基板上に表面実装した状態を示す断面図である。
【図３】本発明の多連型コンデンサの他の実施形態を示す外観斜視図である。
【図４】従来の多連型コンデンサを示す図であり、（ａ）は一部透視状態の外観斜視図、（ｂ）はＸ−Ｘ線断面図である。
【符号の説明】
１０ 多連型コンデンサ（セラミック電子部品）
１ 積層体（部品本体）
２ 誘電体層
３、４ 内部電極
５、６ 外部電極
５ａ、６ａ 平坦部
５ｂ、６ｂ 凸部
１１ 配線基板
１２ 配線パターン
１３ 半田[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ceramic electronic component, and more particularly to a structure of an external electrode of a ceramic electronic component having a plurality of external electrodes on one end surface of a rectangular parallelepiped component body.
[0002]
[Prior art]
A description will be given of a multiple capacitor as an example of a typical ceramic electronic component.
[0003]
4A and 4B are views showing a conventional multiple capacitor, in which FIG. 4A is an external perspective view, and FIG. 4B is a sectional view taken along line XX.
[0004]
In the figure, 30 is a multiple capacitor, 31 is a laminated body, 32 is a dielectric layer constituting the laminated body 31, 33 and 34 are internal electrodes formed inside the laminated body 31, and 35 and 36 are external electrodes. Electrodes.
[0005]
As shown in the figure, the multilayer body 31 of the multiple capacitor 30 is formed by stacking a plurality of dielectric layers 32.
[0006]
Further, for example, a plurality of first and second internal electrodes 33 and 34 are formed between the dielectric layers 32 of the multilayer body 31 so as to face each other. The internal electrode 34 extends to the other end surface of the multilayer body 31.
[0007]
Further, the plurality of external electrodes 35 and 36 are formed so as to straddle the end surface of the multilayer body 31 and the main surface in contact with the end surface. Thereby, the end faces of the external electrodes 25 and 26 are connected to the first and second internal electrodes 33 and 34. In addition, the main surfaces (mounting surfaces) of the external electrodes 25 and 26 are securely mounted on the wiring board.
[0008]
A surface plating layer (not shown) is formed on the surfaces of the external electrodes 35 and 36 as necessary.
[0009]
Such a multiple capacitor 30 is surface-mounted on a wiring pattern on a wiring board with one main surface (mounting surface) down using a bonding material such as solder or a conductive adhesive.
[0010]
[Patent Document 1]
JP-A-2002-57059 (page 2, FIG. 1)
[0011]
[Problems to be solved by the invention]
In recent years, the demand for the multiple capacitors 30 for portable electronic devices such as portable telephones and portable computers has been increasing.
[0012]
However, in a portable electronic device, when used or carried, an impact due to a drop or the like is applied to a multiple capacitor 30 mounted on a wiring board inside the device, and as shown in FIG. 30 has a problem that a crack 38 is generated.
[0013]
The present invention has been devised in view of the above problems, and an object of the present invention is to provide a ceramic electronic component having excellent impact resistance.
[0014]
[Means for Solving the Problems]
The present invention provides a rectangular parallelepiped component body made of a ceramic member having an internal conductor formed thereon, and an external electrode connected to the internal conductor and formed so as to straddle an end surface and a main surface of the component body. In the ceramic electronic component provided, the external electrode has a conductor thickness at a ridge portion between an end surface and a main surface of the component body that is thicker than a conductor thickness formed at a central portion of the end surface of the component body. ing.
[0015]
When the conductor thickness at the ridge of the external electrode is nb and the conductor thickness formed on the end face is na, the nb / na value is 1.1 to 3.0.
[0016]
[Action]
According to the ceramic electronic component of the present invention, the external electrode is formed so as to straddle the end surface and the main surface of the component main body, and the ridge portion between the end surface and the main surface has a thicker conductor film. . In other words, the conductor thickness at the ridge portion is larger than the conductor film at the substantially central portion of the end surface of the component body in the external electrode formation region. The ridge line portion is called a convex portion of the external electrode, and a region where the conductive film is thin is called a flat portion with respect to the convex portion.
[0017]
Since the projection of the external electrode is formed so as to extend over the ridgeline between the end surface and the main surface of the component body, the ceramic electronic component is surface-mounted on a wiring board with a bonding material such as solder. In this state, even if an impact due to a drop or the like is applied to the ceramic electronic component, the occurrence of cracks can be reduced.
[0018]
That is, in many cases, a stress in the torsional direction is applied to the ceramic electronic component due to an impact due to a drop or the like. At this time, cracks are thought to occur starting from the part where the ridgeline of the component body and the external electrode are in contact with the bonding material, and proceed to the side surfaces of the component body.However, the presence of the projection covers the ridgeline of the component body. Since the thickness of the external electrode is increased and the component body is protected from the stress in the torsional direction, it is considered that the occurrence of cracks can be reduced.
[0019]
In addition, since the flat portion of the external electrode is formed substantially at the center of the end surface of the component body, even when the thickness of the external electrode covering the ridge line of the component body is increased, the size of the ceramic electronic component is not increased. As a result, it is possible to realize a small size and a large capacity. In addition, since the thickness of the entire external electrode does not need to be increased, the organic binder resin can be easily removed, and blisters are not generated. As a result, a decrease in electrical characteristics such as capacitance is suppressed. it can. Furthermore, when a ceramic electronic component is surface-mounted on a wiring board with a bonding material, the bonding material only goes up to the height of the flat portion, so that the position where stress is generated in the component body is reduced.
[0020]
BEST MODE FOR CARRYING OUT THE INVENTION
Hereinafter, a ceramic electronic component of the present invention will be described with reference to the drawings.
[0021]
A description will be given of a multiple capacitor as an example of a typical ceramic electronic component.
[0022]
1A and 1B are views showing a multiple capacitor of the present invention, wherein FIG. 1A is an external perspective view, and FIG. 1B is a longitudinal sectional view. FIG. 2 is a sectional view showing a state in which the multiple capacitor of FIG. 1 is surface-mounted on a wiring board.
[0023]
In the figure, 10 is a multiple capacitor (ceramic electronic component), 1 is a laminated body (component body) made of dielectric ceramic, 2 is a dielectric layer, 3 and 4 are internal electrodes, and 5 and 6 are external electrodes. Reference numeral 11 denotes a wiring board, 12 denotes a wiring pattern, and 13 denotes a solder (joining material).
[0024]
As shown in FIG. 1, the multilayer body 1 of the multiple capacitor 10 is formed by laminating a plurality of dielectric layers 2.
[0025]
The dielectric layer 2 is made of a non-reducing dielectric material containing barium titanate (BaTiO ₃ ) as a main component and a dielectric material containing a glass component, and has a shape of 2.0 mm × 1.2 mm or the like. The thickness is set to 1 to 5 μm to increase the capacity. The dielectric layer 2 is stacked in the upward direction in the drawing to form the laminate 1. The shape, thickness, and number of layers of the dielectric layer 2 can be arbitrarily changed according to the capacitance value.
[0026]
For example, a plurality of internal electrodes 3, 4 are formed facing each other between the dielectric layers 2 of the multilayer body 1, and extend to both end surfaces of the multilayer body 1, respectively. The internal electrodes 3 and 4 are made of, for example, a material mainly containing Ni, and have a thickness of 1 to 2 μm.
[0027]
The external electrodes 5 and 6 are attached to the pair of long side end surfaces of the multilayer body 1 and are connected to the internal electrodes 3 and 4, respectively. The external electrodes 5 and 6 are made of a base metal component such as Cu, Ni, or an alloy thereof, and a glass component, and have three surfaces including an end surface on the long side and two main surfaces adjacent to the end surface (one is a mounting surface). Formed over Further, a surface plating layer (not shown) is formed on the surfaces of the external electrodes 5 and 6. Examples of the surface plating layer include Ni plating, Sn plating, and solder plating.
[0028]
A feature of the present invention is that the conductor thickness of the ridge portion between the end surface and the main surface of the laminate 1 of the external electrodes 5 and 6 is smaller than the conductor thickness formed at the center of the end surface of the laminate 1. It is getting thicker. That is, the external electrodes 5 and 6 include flat portions 5a and 6a formed substantially at the center of the end face of the multilayer body 1 and convex portions 5b and 6b adjacent to the flat portions 5a and 6a and extending over the main surface. That is.
[0029]
Here, as for the thickness na of the flat portions 5a and 6a, the ratio of the maximum value to the minimum value is preferably 1.5 or less, more preferably 1.2 or less. Also, it is desirable that the shapes of the convex portions 5b and 6b are dome shapes.
[0030]
Hereinafter, a method for manufacturing the multiple capacitor 10 of the present invention will be described. Each code is not distinguished before and after firing.
[0031]
First, a conductive paste is formed on a ceramic green sheet 2 serving as a dielectric layer by screen printing, and conductive films 3 and 4 serving as internal electrodes are formed.
[0032]
Then, after stacking a predetermined number of such ceramic green sheets 2 so that the conductor films 3 and 4 face each other and the conductor films 3 and 4 extend to different end faces, the ceramic green sheets 2 are cut and each capacitor is cut. The unfired laminate 1 including the unit N is fired under a predetermined atmosphere, temperature and time. Thus, the internal electrodes 3 and 4 are exposed on the pair of end surfaces of the multilayer body 1 for each capacitor unit N.
[0033]
Thereafter, in order to electrically connect each capacitor unit N to the outside, the conductor films 5 and 6 serving as external electrodes are applied to the end face of the laminate 1 and two adjacent faces by a screen printing method and a transfer method from a roller. It is applied by, for example.
[0034]
At this time, the conductor films 5 and 6 have flat portions 5a and 6a formed substantially at the center of the end surface of the multilayer body 1 and have a convex portion which is adjacent to the flat portions 5a and 6a by the edge effect and straddles the main surface. 5b and 6b are formed.
[0035]
After removing the binder component from the conductive films 5 and 6 in the air at 250 ° C. to 400 ° C., the external electrodes 5 and 6 are formed by baking at 800 to 900 ° C. in a neutral or reducing atmosphere.
[0036]
Thereafter, surface plating layers (not shown) are formed on the external electrodes 5 and 6 by electrolytic plating or electroless plating. At this time, since the protrusions 5b, 6b of the external electrodes 5, 6 are less likely to be plated than the flat portions 5a, 6a, the difference between the thickness na of the flat portions 5a, 6a and the thickness nb of the protrusions 5b, 6b is determined. It can be further accumulated.
[0037]
Thus, the multiple capacitor 10 of the present invention is obtained.
[0038]
Thus, according to the multiple capacitor 10 of the present invention, the external electrodes 5, 6 are formed at the flat portions 5 a, 6 a formed substantially at the center of the end face of the multilayer body 1, and around the flat portions 5 a, 6 a. And convex portions 5b and 6b extending over the ridge line between the end surface and the main surface. For this reason, in a state where the multiple capacitor 10 is surface-mounted on the wiring pattern 12 on the wiring board 11 by the solder 13, the occurrence of cracks 38 can be reduced even if an impact due to a drop or the like is applied to the multiple capacitor 10.
[0039]
That is, in many cases, a stress in the torsional direction is applied to the multiple capacitor 10 by an impact due to a drop or the like. At this time, it is considered that a crack 38 is generated starting from a portion where the ridgeline of the laminate 1 is in contact with the external electrodes 5 and 6 and the solder 13 and proceeds to the side surface of the laminate 1, but the protrusions 5b and 6b It is considered that the presence thereof increases the thickness rt of the external electrodes 5 and 6 covering the ridge line of the multilayer body 1 and protects the multilayer body 1 from the stress in the torsional direction, so that the occurrence of cracks 38 can be reduced.
[0040]
In addition, since the flat portions 5a and 6a of the external electrodes 5 and 6 are formed substantially at the center of the end surface of the multilayer body 1, the thickness rt of the external electrodes 5 and 6 covering the ridge line of the multilayer body 1 increases. However, the size of the multiple capacitor 10 in the width direction (W direction) does not need to be increased, so that a large-sized capacitor can be realized. In addition, since it is not necessary to increase the thickness of the external electrodes 5 and 6 as a whole, the organic binder resin can be easily removed, and no blister is generated. As a result, for example, electric characteristics such as capacitance can be reduced. Reduction can be suppressed. Furthermore, when the multiple capacitor 10 is surface-mounted on the wiring pattern 12 on the wiring board 11 by the solder 13, the solder 13 rises only up to the height of the flat portion, so that the position where the stress occurs in the laminate 1 is low. Become.
[0041]
Here, as shown in FIG. 1B, in order to effectively reduce the occurrence of cracks 38, when the radius of curvature of the ridge line portion of the laminate 1 is r1, the rt / r1 ratio is Desirably, it is 0.25 or more.
[0042]
Further, the ratio ma / T of the dimension ma in the height direction of the flat portions 5a and 6a to the dimension T in the height direction of the laminate 1 is in the range of 0.2 to 0.8, preferably 0.3 to 0.5. Is desirable. That is, when the ma / T ratio is less than 0.2, the above-mentioned effects such as the reduction in size and the capacity are not sufficiently exhibited. On the other hand, when the ma / T ratio exceeds 0.8, the effect of reducing the occurrence of cracks 38 due to impact due to dropping or the like does not sufficiently appear.
[0043]
The ratio nb / na between the thickness na of the flat portions 5a and 6a and the thickness nb of the convex portions 5b and 6b (the thickness at the end face side of the laminate 1 is used for comparison with the flat portions 5a and 6a) is , 1.1-3.0, preferably 1.5-2.4. That is, when the nb / na ratio is less than 1.1, the effect of reducing the occurrence of cracks 38 due to an impact due to a drop or the like while sufficiently exhibiting the effects of the above-described small size and large capacity is not sufficiently exhibited. On the other hand, when the nb / na value ratio exceeds 3.0, it becomes difficult to accurately form the flat portions 5a and 6a and the convex portions 5b and 6b, and the flat portions 5a and 6a are damaged by an external impact, and the convex portions 5b and 6b are chipped. Will occur. For this reason, it cannot be actually used.
[0044]
It should be noted that the present invention is not limited to the above embodiments, and various changes and improvements may be made without departing from the spirit of the present invention.
[0045]
For example, in the above embodiments, a multiple capacitor was used as the ceramic electronic component. However, the present invention is applied to a case where the external electrode is formed so as to extend from the end face of the component body to three or four faces adjacent thereto. It can also be applied to the multilayer ceramic capacitor. Further, the present invention can be applied to a ceramic electronic component in which an external electrode is formed so as to extend from an end surface of the component main body to only one surface adjacent thereto. Further, the present invention can be applied to other electronic components and other ceramic electronic components such as semiconductor components.
[0046]
FIG. 3 is an external perspective view showing another embodiment of the multiple capacitor 10 of the present invention. As shown, the flat portions 5a and 6a of the external electrodes 5 and 6 may be formed only at substantially the center in the horizontal direction in the drawing. This makes it difficult for the protrusions 5b and 6b to be damaged by an external impact.
[0047]
Further, as a method of forming the flat portions 5a, 6a and the convex portions 5b, 6b of the external electrodes 5, 6, the mesh of the screen plate is made to have an opening larger than that of the flat portions 5a, 6a. May be made larger. Further, the application and baking of the conductive paste to be the external electrodes 5 and 6 in a predetermined shape may be performed two or more times. That is, the difference between the thickness na of the flat portions 5a and 6a and the thickness nb of the convex portions 5b and 6b is accumulated and can be further increased. At this time, the second and subsequent application of the conductive paste may be performed only on the portions that become the protruding portions 5b and 6b by using a screen plate different from that of the first application. This also makes it possible to further increase the difference between the thickness na of the flat portions 5a and 6a and the thickness nb of the convex portions 5b and 6b.
[0048]
【Example】
The present inventor produced a multiple capacitor 10 in which the external electrodes 5 and 6 had flat portions 5a and 6a and convex portions 5b and 6b by the above method. Here, the dimensions of the multiple capacitor 10 were 2.0 mm × 1.2 mm. Further, by adjusting the properties of the conductive paste such as solid content and viscosity, and the size of the mesh of the screen plate, the ma / T ratio and the nb / na ratio are adjusted so as to fall within the range of rt / r1 ≧ 0.25. The ratio was varied. (Sample Nos. 2 to 6, 8 to 11) Further, the thickness na of the flat portions 5a and 6a is in the range of 10 to 35 μm, and the thickness nb of the convex portions 5b and 6b is in the range of 20 to 60 μm, and na <nb. I did it. And these thicknesses na and nb were confirmed from the SEM image of the fracture surface of the multiple capacitor 10.
[0049]
As comparative examples, the multiple capacitors 30 (sample No. 7) in which the projections 5b and 6b are not formed on the external electrodes 5 and 6 (the total thickness of the external electrodes 5 and 6 is in the range of 10 to 35 μm), and the external electrodes A multiple capacitor 30 (sample No. 1) in which the concave portions 5a and 6a are not formed in 5 and 6 (the total thickness of the external electrodes 5 and 6 is in the range of 20 to 60 μm) was also manufactured.
[0050]
About the obtained sample, the measurement of the dimension of W direction and the drop test were performed.
[0051]
Regarding the dimension in the width direction, ten samples were measured with calipers, and the largest value was obtained.
[0052]
In the drop test method, as shown in FIG. 2, 100 samples were surface-mounted on a wiring pattern 12 on a 1.6 mm thick glass epoxy substrate (wiring board) 11 by soldering. Then, the substrate 11 was set in a resin case, dropped on a concrete plate from a height of 2 m, and the incidence of cracks 38 was determined by a metallographic microscope.
[0053]
The evaluation criteria are circles as non-defective products in which the dimension in the W direction is 1.47 mm or less and the rate of occurrence of cracks 38 is 5% or less even when dropped from a height of 2 m. Further, among the non-defective products, the case where the dimension in the W direction is 1.4 mm or less and the occurrence rate of the crack 38 is 0% is indicated by a double circle. On the other hand, a case where the dimension in the W direction exceeds 1.47 mm or a case where the occurrence rate of the crack 38 exceeds 5% is marked with a cross as a defective product.
[0054]
Table 1 shows the results.
[0055]
[Table 1]

[0056]
As shown in the table, in this embodiment (sample numbers 2 to 6 and 8 to 11) in which the external electrodes 5 and 6 include the flat portions 5a and 6a and the convex portions 5b and 6b, the range of rt / r1 ≧ 0.25 is satisfied. Also, when it was made to enter, the dimension in the W direction was 1.47 mm or less, and the incidence of cracks 38 when dropped on a concrete plate from a height of 2 m was 5% or less. In particular, when the ma / T ratio is 0.3 or more and the nb / na ratio is 1.5 or more (sample numbers 3 to 5 and 9 to 11), the dimension in the W direction is 1.4 mm or less. At the same time, the incidence of cracks 38 became 0% or less.
[0057]
On the other hand, in the comparative example (sample No. 7) in which the projections 5b and 6b are not formed on the external electrodes 5 and 6, rt / r1 <0.25, and when the sample is dropped on a concrete plate from a height of 2 m, 40% of cracks 38 occurred.
[0058]
On the other hand, in the comparative example (sample No. 1) in which the concave portions 5a and 6a are not formed in the external electrodes 5 and 6, the dimension in the W direction is larger than 1.47 mm when rt / r1 ≧ 0.25. became.
[0059]
From these results, in the multiple capacitor 10 of the present invention, the external electrodes 5, 6 are adjacent to the flat portions 5 a, 6 a formed substantially at the center of the end face of the component body 1 and the flat portions 5 a, 6 a. Since the projections 5b and 6b straddle the main surface, the size of the cracks 38 can be reduced even if an impact due to a drop or the like is applied in a mounted state without increasing the dimension in the W direction.
[0060]
【The invention's effect】
ADVANTAGE OF THE INVENTION According to the ceramic electronic component of this invention, since the thickness of the external electrode of the edge part of the end surface of a component main body and the main surface was thickened, it is excellent in impact resistance.
[0061]
Further, a flat portion of the external electrode is formed substantially at the center of the end surface of the component body, and it is not necessary to increase the thickness of the entire external electrode. This has the effect of reducing the height at which the joining material rises.
[Brief description of the drawings]
FIG. 1 is a view showing a multiple capacitor of the present invention, wherein (a) is an external perspective view and (b) is a cross-sectional view taken along line XX.
FIG. 2 is a sectional view showing a state in which the multiple capacitor of FIG. 1 is surface-mounted on a wiring board.
FIG. 3 is an external perspective view showing another embodiment of the multiple capacitor of the present invention.
4A and 4B are views showing a conventional multiple capacitor, in which FIG. 4A is an external perspective view in a partially transparent state, and FIG. 4B is a sectional view taken along line XX.
[Explanation of symbols]
10 Multiple capacitors (ceramic electronic components)
1 laminated body (part body)
2 Dielectric layer 3, 4 Internal electrode 5, 6 External electrode 5a, 6a Flat portion 5b, 6b Convex portion 11 Wiring board 12 Wiring pattern 13 Solder

Claims (2)

A ceramic comprising: a rectangular parallelepiped component body made of a ceramic member having an internal conductor formed thereon; and external electrodes connected to the internal conductor and formed so as to extend over an end face and a main surface of the component body. In electronic components,
The external electrode, wherein a conductor thickness at a ridge portion between an end surface and a main surface of the component body is thicker than a conductor thickness formed at a central portion of an end surface of the component body. Electronic components. The nb / na value is 1.1 to 3.0, where nb is the conductor thickness of the ridge portion of the external electrode and na is the conductor thickness formed on the end face. Ceramic electronic components.

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