JP6866678B2 - Electronic components - Google Patents

Description

The present invention relates to electronic components.

A pair of main surfaces that are smaller in the height direction than the length in the longitudinal direction and the length in the width direction and that face each other in the height direction, and a pair of end faces that face each other in the longitudinal direction. A pair of external electrodes arranged on each end surface and having curved corners connecting the main surface and the end surface, and a pair of external electrodes facing each other in the longitudinal direction, and an external electrode. Electronic components are known to include an internal conductor that is connected (eg, Patent Document 1).

Japanese Unexamined Patent Publication No. 2006-229005

An object of the present invention is to provide an electronic component in which structural defects are unlikely to occur in an element body.

The present inventors have conducted research on electronic components that are unlikely to have structural defects, particularly chips and cracks, in the element body.

The element body may be chipped, for example, in the manufacturing process. An impact is applied to the elements when the elements collide with each other or when the elements collide with manufacturing equipment other than the elements. Since the corner portion (ridge portion) connecting two adjacent surfaces has relatively low strength, there is a high possibility that the corner portion will be chipped when an impact is applied to the corner portion.

When electronic components are used in a high temperature and high humidity environment, cracks may occur in the element body. According to the consideration of the present inventors, the cause of the crack is considered to be the water that invades the body. That is, when an electronic component is used in a high temperature and high humidity environment, moisture passes through the external electrode and penetrates into the interface between the external electrode and the element body due to the pressure difference between the outside and the inside of the external electrode. Since the inner conductor is connected to the outer electrode, its end is exposed on the surface of the element body. Therefore, the water that has infiltrated to the interface between the external electrode and the element body passes through the end of the inner conductor or the interface between the inner conductor and the element body and invades into the element body to generate a crack.

Then, the present inventors conducted further research and found the following facts. That is, the present inventors have found that the radius of curvature of the corner portion, the length of the element body in the height direction, and the thickness of the external electrode are related to the occurrence of chipping and cracking, and conceived the present invention. It came to.

The radius of curvature of the corner and the length of the element in the height direction are related to the occurrence of chipping. When the radius of curvature of the corner is R, the length of the element in the height direction is H, and 0.08 ≤ R / H ≤ 0.25 is satisfied, the corner of the element is chipped. hard. The radius of curvature of the corner and the thickness of the external electrode are related to the occurrence of cracks. When the thickness from the end face of the external electrode on the straight line passing through the center of each end face is T, if 0.71 ≦ T / R ≦ 1.27 is satisfied, the electronic component is used in a high temperature and high humidity environment. Even if it is done, cracks are unlikely to occur in the body.

The electronic component according to the present invention has a pair of main surfaces that are smaller in the height direction than the length in the longitudinal direction and the length in the width direction and that face each other in the height direction. A body having a pair of end faces facing each other in the longitudinal direction and curved corners connecting the main face and the end faces, and a body arranged on each end face and facing each other in the longitudinal direction. It is provided with a pair of external electrodes and an internal conductor connected to the external electrodes, the radius of curvature of the corner is R, the length of the element in the height direction is H, and a straight line passing through the center of each end face. When the thickness from the end face of the external electrode in the above is T, 0.08 ≦ R / H ≦ 0.25 and 0.71 ≦ T / R ≦ 1.27 are satisfied.

In the electronic component according to the present invention, structural defects, particularly chips and cracks, are unlikely to occur in the element body.

According to the present invention, it is possible to provide an electronic component in which structural defects are unlikely to occur in the element body.

It is a schematic perspective view which shows the multilayer capacitor which concerns on one Embodiment. It is a top view of a multilayer capacitor. It is a figure for demonstrating the cross-sectional structure of a multilayer capacitor. It is a figure for demonstrating the cross-sectional structure of a multilayer capacitor.

Hereinafter, embodiments of the present invention will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals will be used for the same elements or elements having the same function, and duplicate description will be omitted.

First, the configuration of the multilayer capacitor according to the present embodiment will be described with reference to FIGS. 1 to 3. FIG. 1 is a schematic perspective view showing a multilayer capacitor according to the present embodiment. FIG. 2 is a plan view of the multilayer capacitor. FIG. 3 is a cross-sectional view of the multilayer capacitor cut in the longitudinal direction. In this embodiment, the multilayer capacitor 1 will be described as an example of an electronic component.

As shown in FIG. 1, the multilayer capacitor 1 includes an element body 2, a pair of external electrodes 5 and 6 arranged on the outer surface of the element body 2, and a plurality of external electrodes 5 and 6 arranged inside the element body 2. It includes an internal electrode 11 and a plurality of internal electrodes 13 arranged inside the element body 2. In this embodiment, the multilayer capacitor 1 is solder-mounted on an electronic device (for example, a circuit board or other electronic component) 20 as shown in FIG. A solder fillet 22 is formed between the external electrodes 5 and 6 and the pad electrodes (not shown) of the electronic device 20.

The element body 2 has a rectangular parallelepiped shape in which the length in the height direction D3 is smaller than the length in the longitudinal direction D1 and the width direction D2. The length L of the element body 2 in the longitudinal direction D1 is 0.6 to 1.6 mm, the length W of the width direction D2 is 0.3 to 0.8 mm, and the length H of the height direction D3 is 0. .1 to 0.7 mm.

The element body 2 has a pair of main surfaces 2a, a pair of end surfaces 2b and 2c, a pair of side surfaces 2d, and a corner portion (ridge portion) 2e connecting two adjacent surfaces as its outer surface. doing. The pair of main surfaces 2a face each other in the height direction D3. The pair of end faces 2b and 2c face each other in the longitudinal direction D1. The pair of side surfaces 2d face each other in the width direction D2. In the multilayer capacitor 1, one main surface 2a is a mounting surface facing the electronic device 20.

Each corner 2e is rounded so as to be curved. That is, each corner portion 2e has a curved surface shape. The corner 2e is located between two adjacent surfaces. The radius of curvature R of each corner portion 2e satisfies 0.08 ≦ R / H ≦ 0.25 in relation to the length H of the element body 2 in the height direction D3. The rectangular parallelepiped shape includes a rectangular parallelepiped shape with rounded corners.

The element body 2 is configured by laminating a plurality of dielectric layers in the height direction D3 where the pair of main surfaces 2a face each other. In the element body 2, the stacking direction of the plurality of dielectric layers coincides with the height direction D3. Each dielectric layer is from a sintered body of a ceramic green sheet containing, for example, a dielectric material (a dielectric ceramic such as BaTiO ₃ series, Ba (Ti, Zr) O ₃ series, or (Ba, Ca) TiO _{3 series).} It is composed. In the actual element body 2, each dielectric layer is integrated to such an extent that the boundary between the respective dielectric layers cannot be visually recognized.

As shown in FIG. 1, the pair of external electrodes 5 and 6 are arranged at both ends of the element body 2 in the longitudinal direction. The pair of external electrodes 5 and 6 are separated from each other and face each other in the longitudinal direction D1. The external electrodes 5 and 6 are arranged on the pair of conductor portions 5a and 6a arranged on the main surface 2a, the conductor portions 5b and 6b arranged on the end surfaces 2b and 2c, and the side surface 2d. It has a pair of conductor portions 5c and 6c, and conductor portions 5d and 6d arranged on the corner portions 2e. In the external electrode 5, the conductor portions 5a, 5b, and 5c are connected to each other by the conductor portion 5d, respectively. In the external electrode 6, the conductor portions 6a, 6b, and 6c are connected to each other by the conductor portions 6d, respectively.

The plurality of internal electrodes 11 and 13 are arranged at different positions (layers) in the height direction of the element body 2. That is, the internal electrodes 11 and 13 are alternately arranged in the element body 2 so as to face each other with an interval in the height direction D3. The internal electrode 11 and the internal electrode 13 are made of a conductive material (for example, Ni or Cu) that is usually used as an internal conductor of a laminated electric element. The internal electrode 11 and the internal electrode 13 are configured as a sintered body of a conductive paste containing the above conductive material.

Each internal electrode 11 has a rectangular shape in which the longitudinal direction D1 is the long side direction and the width direction D2 is the short side direction. Each internal electrode 11 is exposed on the end surface 2b and not on the end surface 2c, the pair of main surfaces 2a, and the pair of side surfaces 2d. Each internal electrode 11 is connected to an external electrode 5 at the end face 2b. The internal electrode 11 is an internal conductor connected to the external electrode 5.

Each internal electrode 13 faces the internal electrode 11 in the height direction D3 via a part (dielectric layer) of the element body 2. Each internal electrode 13 has a rectangular shape in which the longitudinal direction D1 is the long side direction and the width direction D2 is the short side direction. Each internal electrode 13 is exposed on the end surface 2c and not on the end surface 2b, the pair of main surfaces 2a, and the pair of side surfaces 2d. Each internal electrode 13 is connected to an external electrode 6 at the end face 2c. The internal electrode 13 is an internal conductor connected to the external electrode 6.

Next, a detailed configuration of the external electrode 5 will be described with reference to FIG. FIG. 4 is a partially enlarged view of the multilayer capacitor 1 shown in FIG. Since the external electrode 6 has the same configuration as the external electrode 5, the illustration is omitted.

The external electrodes 5 and 6 have an electrode layer 23, a first plating layer 25, and a second plating layer 27. Specifically, in the external electrodes 5 and 6, a first plating layer 25 is formed on the electrode layer 23 by a plating treatment (for example, an electroplating treatment), and a second plating layer 27 is formed on the first plating layer 25. Is formed. The conductor portions 5a, 5b, 5c, 5d, 6a, 6b, 6c, 6d include an electrode layer 23, a first plating layer 25, and a second plating layer 27.

The electrode layer 23 is formed by applying a conductive paste to the surface of the element body 2 and baking it. The electrode layer 23 is a sintered metal layer formed by sintering a metal component (metal powder) contained in the conductive paste. In the present embodiment, the electrode layer 23 is a sintered metal layer made of Cu. The electrode layer 23 may be a sintered metal layer made of Ni. As the conductive paste, a powder made of Cu or Ni mixed with a glass component, an organic binder, and an organic solvent is used.

In the present embodiment, the first plating layer 25 is a Ni plating layer formed by Ni plating. The first plating layer 25 may be a Sn plating layer, a Cu plating layer, or an Au plating layer. The second plating layer 27 is a Sn plating layer formed by Sn plating. The second plating layer 27 may be a Cu plating layer or an Au plating layer.

The conductor portions 5b, 6b of the pair of external electrodes 5, 6 cover the entire corresponding end faces 2b, 2c. The entire end faces 2b and 2c mean the entire region surrounded by the conductor portions 5d and 6d. The conductor portions 5a, 6a and the conductor portions 5c, 6c cover the entire region of the portion having a predetermined length in the longitudinal direction D1 from the end faces 2b, 2c at both ends of the element body 2. The thickness T of each conductor portion 5b, 6b from the end faces 2b, 2c on the straight line A passing through the center of each end face 2b, 2c is 0.71 ≦ T / R in relation to the radius of curvature R of the corner portion 2e. ≤ 1.27 is satisfied.

As described above, in the multilayer capacitor 1, the radius of curvature R of the corner portion 2e, the length H of the element body 2 in the height direction D3, and the external surface on the straight line A passing through the centers of the end faces 2b and 2c. The relationship between the thickness of the electrodes 5 and 6 from the end faces 2b and 2c and T satisfies 0.08 ≦ R / H ≦ 0.25 and 0.71 ≦ T / R ≦ 1.27. Therefore, the multilayer capacitor 1 is less likely to be chipped at the corners 2e of the element body 2 and cracks at the end faces 2b and 2c of the element body 2 are unlikely to occur. That is, in the multilayer capacitor 1, structural defects are unlikely to occur in the element body 2.

Here, examples of the present invention will be described in order to explain the above effects. The present invention is not limited to the following examples. Here, a multilayer capacitor having the same configuration as that of the multilayer capacitor 1 and a multilayer capacitor as a comparative example were prepared, and it was confirmed whether or not a structural defect had occurred in the element body.

1000 elements were prepared for each of Examples 1 to 7 and Comparative Examples 1 to 6. Specifically, 1000 element bodies having the same length W in the width direction D2 of the element body, length H in the height direction D3 of the element body, and radius of curvature R at the corners were formed. Before forming the terminal electrodes, each element was cut and the cut surface was polished. After that, the polished cut surface was observed with an electron microscope to confirm whether or not the corners of the element body were chipped.

The results are shown in Table 1. When a chip was confirmed in one or more of the 1000 elements, an "x" was added in the "chip" column. When no chipping was confirmed in 1000 elements, "○" was marked in the "missing" column. When cracks occurred in one or more of the 1000 elements, "x" was marked in the "crack" column. When no cracks occurred in 1000 elements, "○" was marked in the "crack" column.

As shown in Table 1, in Comparative Example 1, the element body was cracked in the height direction D3, and in Comparative Examples 2 to 6, the corner portion 2e was chipped. On the other hand, in Examples 1 to 7, neither crack in the height direction D3 nor chipping at the corner was observed. That is, when the R / H was in the range of 0.08 to 0.25, the element body was not cracked and the corners were not chipped. From the above, it was confirmed that when 0.08 ≦ R / H ≦ 0.25 is satisfied, the occurrence of cracking of the element body and chipping of the corners is suppressed.

Subsequently, an accelerated moisture resistance load test (PCBT test: Pressure Cooker Biased Test) was carried out. First, 1000 elements were prepared for each of Examples 8 to 11 and Comparative Examples 7 to 9. Specifically, 1000 elements having the same length W in the width direction D2 of the element body, length H in the height direction D3 of the element body, the thickness T of the external electrode, and the radius of curvature R of the corners are formed. did. Then, an external electrode was formed on each element body to prepare a multilayer capacitor. A voltage was applied to the produced multilayer capacitor in an atmosphere of a temperature of 121 ° C. and a humidity of 95% in a test tank.

After the accelerated moisture resistance load test, each laminated capacitor was cut and the cut surface was polished. After that, the polished cut surface was observed with an electron microscope to confirm whether or not cracks were generated in the element body. The results are shown in Table 2. When cracks were confirmed in one or more of the 1000 elements, "x" was marked in the "crack" column. When no crack was confirmed in 1000 elements, "○" was marked in the "crack" column.

As shown in Table 2, in Comparative Examples 7 to 9, cracks were generated in the end faces 2b and 2c of the element body. On the other hand, in Examples 8 to 11, no cracks were observed in the end faces 2b and 2c of the element body. That is, when the T / R was in the range of 0.71 to 1.27, no cracks were generated in the end faces 2b and 2c of the element body. From the above, it was confirmed that the occurrence of cracks in the element body was suppressed when 0.71 ≦ T / R ≦ 1.27 was satisfied.

Although the embodiments of the present invention have been described above, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the gist thereof.

In the present embodiment, a laminated capacitor has been described as an example, but the present invention is not limited to this, and the present invention is not limited to this, and a laminated electronic component such as a laminated through capacitor, a laminated inductor, a laminated varistor, a laminated piezoelectric actuator, a laminated thermistor, or a laminated composite component Or, it can be applied to electronic components other than laminated electronic components.

1 ... Multilayer capacitor, 2 ... Element body, 2a ... Main surface, 2b, 2c ... End surface, 2e ... Corner, 5, 6 ... External electrode, 11, 13 ... Internal electrode, D1 ... Longitudinal direction of element body, D2 ... Width direction of the body, D3 ... Height direction of the body.

Claims (1)

The length in the height direction is smaller than the length in the longitudinal direction and the length in the width direction, and the pair of main surfaces facing each other in the height direction and the pair of main surfaces facing each other in the longitudinal direction face each other. A body having a pair of end faces and curved corners connecting the main face and the end faces.
A pair of external electrodes arranged on each of the end faces and facing each other in the longitudinal direction,
With an internal conductor connected to the external electrode,
The radius of curvature of the corner portion was R, the length of the element body in the height direction was H, and the thickness of the external electrode from the end face on a straight line passing through the center of each end face was T. When
0.08 ≤ R / H ≤ 0.25
0.71 ≤ T / R ≤ 1.27
R ≤ 35 μm
Meet, electronic components.

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