JP7752003B2 - Ceramic electronic components and circuit boards - Google Patents

Description

The present invention relates to a ceramic electronic component and a circuit board having a pair of terminal electrodes.

A multilayer ceramic capacitor comprises a ceramic body containing multiple stacked internal electrodes, and a pair of external electrodes covering the ends of the ceramic body. Multilayer ceramic capacitors are mounted by soldering the pair of external electrodes to a pair of terminals on a mounting substrate. Multilayer ceramic capacitors are mounted, for example, using the reflow method.

When mounting a multilayer ceramic capacitor, if the solder spreads onto one of the pair of external electrodes first, the multilayer ceramic capacitor may stand up due to the surface tension of the solder acting on that external electrode (see, for example, paragraph 0008 and Figure 3 of Patent Document 1). This phenomenon is known as tombstoning.

In contrast, the multilayer ceramic capacitor described in Patent Document 1 is designed so that the end faces of the external electrodes are less likely to bulge outward, thereby suppressing the occurrence of tombstoning during mounting. Specifically, in this multilayer ceramic capacitor, the end faces of the ceramic body are made concave, which makes it easier for the end faces of the external electrodes to be flat.

Japanese Patent Application Laid-Open No. 2000-49032

In recent years, multilayer ceramic capacitors have become smaller and thinner, along with their height reduction, in response to trends such as thinner smartphones and wearable devices, increased functionality, and larger battery capacities. However, it has been confirmed that lighter multilayer ceramic capacitors tend to be more susceptible to tombstoning during mounting.

As multilayer ceramic capacitors become increasingly lightweight, it is expected to become increasingly difficult to fully prevent tombstoning during mounting. For this reason, there is a demand for technology that can more effectively suppress tombstoning during mounting of multilayer ceramic capacitors.

In light of the above circumstances, the object of the present invention is to provide ceramic electronic components and circuit boards that are less likely to cause mounting defects.

To achieve the above object, a ceramic electronic component according to one aspect of the present invention includes a ceramic body, a first external electrode unit, and a second external electrode unit.
The ceramic body has first and second main surfaces perpendicular to a first axis, first and second end surfaces perpendicular to a second axis perpendicular to the first axis, first and second side surfaces perpendicular to a third axis perpendicular to the first and second axes, and first and second ridge portions connecting the first and second side surfaces to the first main surface, respectively.
The first external electrode unit is provided on the first end face side of the ceramic body and includes: a first terminal electrode covering the first end face and extending from the first end face to the first main surface, and a pair of first auxiliary electrodes spaced apart from the first terminal electrode and spaced apart from each other, and extending from the first and second edge portions along the first main surface in the third axis direction.
The second external electrode unit is provided on the second end face side of the ceramic body and includes: a second terminal electrode covering the second end face and extending from the second end face to the first main surface, and a pair of second auxiliary electrodes spaced apart from the second terminal electrode and spaced apart from each other, and extending from the first and second ridge portions along the first main surface in the third axis direction.
When the first main surface is viewed from the front, approximately central portions of the first and second terminal electrodes in the direction of the third axis bulge toward the center of the ceramic body in the direction of the second axis.
The edge of each of the pair of first auxiliary electrodes on the first end face side is closer to the first end face in the direction of the second axis than the apex of the bulge at the approximately central portion of the first terminal electrode.
The edge of each of the pair of second auxiliary electrodes on the second end face side is closer to the second end face in the second axis direction than the apex of the bulge at the approximately central portion of the second terminal electrode.

When mounting this ceramic electronic component, the first external electrode unit is soldered to the first terminal of the mounting substrate, and the second external electrode unit is soldered to the second terminal of the mounting substrate. During the mounting process, the surface tension of the molten solder acts on the first external electrode unit on the first terminal and on the second external electrode unit on the second terminal.
In the first external electrode unit, a force acts on the first auxiliary electrode in a direction opposite to a force acting on the first terminal electrode to make the ceramic electronic component stand up on the first terminal, and in the second external electrode unit, a force acts on the second auxiliary electrode in a direction opposite to a force acting on the second terminal electrode to make the ceramic electronic component stand up on the second terminal.
As a result, even if the molten solder spreads over one of the first and second external electrode units first during the mounting process, the ceramic electronic component is less likely to become tombstoned, meaning that the ceramic electronic component stands up. Therefore, the ceramic electronic component can effectively prevent mounting defects.

The first terminal electrode, the pair of first auxiliary electrodes, the second terminal electrode, and the pair of second auxiliary electrodes may include a sintered film of a conductive material.

The pair of first auxiliary electrodes may extend in the first axis direction from the first and second ridge portions along the first and second side surfaces, respectively.
The pair of second auxiliary electrodes may extend in the first axis direction from the first and second ridge portions along the first and second side surfaces, respectively.

The dimension of the pair of first auxiliary electrodes in the second axis direction may be 2% to 10% of the dimension of the first terminal electrode in the second axis direction.
The dimension of the pair of second auxiliary electrodes in the second axis direction may be 2% to 10% of the dimension of the second terminal electrode in the second axis direction.

A distance between the first terminal electrode and the pair of first auxiliary electrodes may be 2% to 10% of a dimension of the first terminal electrode in the second axis direction.
The distance between the second terminal electrode and the pair of second auxiliary electrodes may be 2% to 10% of the dimension of the second terminal electrode in the second axis direction.

A circuit board according to one embodiment of the present invention includes a ceramic electronic component and a mounting substrate.
The ceramic electronic component includes a ceramic body, a first external electrode unit, and a second external electrode unit.
The ceramic body has first and second main surfaces perpendicular to a first axis, first and second end surfaces perpendicular to a second axis perpendicular to the first axis, first and second side surfaces perpendicular to a third axis perpendicular to the first and second axes, and first and second ridge portions connecting the first and second side surfaces to the first main surface, respectively.
The first external electrode unit is provided on the first end face side of the ceramic body and includes: a first terminal electrode covering the first end face and extending from the first end face to the first main surface, and a pair of first auxiliary electrodes spaced apart from the first terminal electrode and spaced apart from each other, and extending from the first and second edge portions along the first main surface in the third axis direction.
The second external electrode unit is provided on the second end face side of the ceramic body and includes: a second terminal electrode covering the second end face and extending from the second end face to the first main surface, and a pair of second auxiliary electrodes spaced apart from the second terminal electrode and spaced apart from each other, and extending from the first and second ridge portions along the first main surface in the third axis direction.
The mounting board has a substrate main body, a first terminal provided on the substrate main body and having the first terminal electrode and the first auxiliary electrode soldered thereto, and a second terminal provided on the substrate main body and having the second terminal electrode and the second auxiliary electrode soldered thereto.
When the first main surface is viewed from the front, approximately central portions of the first and second terminal electrodes in the direction of the third axis bulge toward the center of the ceramic body in the direction of the second axis.
The edge of each of the pair of first auxiliary electrodes on the first end face side is closer to the first end face in the direction of the second axis than the apex of the bulge at the approximately central portion of the first terminal electrode.
The edge of each of the pair of second auxiliary electrodes on the second end face side is closer to the second end face in the second axis direction than the apex of the bulge at the approximately central portion of the second terminal electrode.

The present invention provides ceramic electronic components and circuit boards that are less likely to cause mounting defects.

1 is a perspective view of a multilayer ceramic capacitor according to an embodiment of the present invention; 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line AA' in FIG. 1. 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line BB' in FIG. 1. FIG. 2 is a plan view of the multilayer ceramic capacitor. 2 is a cross-sectional view of the multilayer ceramic capacitor taken along line CC' in FIG. 1. FIG. 2 is a side view of a circuit board on which the multilayer ceramic capacitor is mounted. 10A to 10C are side views showing a mounting process of the comparative example of the multilayer ceramic capacitor. FIG. 2 is a plan view of the multilayer ceramic capacitor.

Hereinafter, an embodiment of the present invention will be described with reference to the drawings.
The drawings show mutually orthogonal X-axis, Y-axis, and Z-axis, which are common to all the drawings.

[Overall Configuration of Multilayer Ceramic Capacitor 10]
1 to 3 are diagrams showing a multilayer ceramic capacitor 10 according to one embodiment of the present invention. Fig. 1 is a perspective view of the multilayer ceramic capacitor 10. Fig. 2 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along line AA' in Fig. 1. Fig. 3 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along line BB' in Fig. 1.

The multilayer ceramic capacitor 10 comprises a ceramic body 11, a first terminal electrode 14a, and a second terminal electrode 15a. The ceramic body 11 constitutes the main body of the multilayer ceramic capacitor 10. The terminal electrodes 14a, 15a constitute a pair of terminals for receiving electrical connections in the multilayer ceramic capacitor 10.

The ceramic body 11 is configured as a hexahedron with outer surfaces including first and second end faces E1, E2 perpendicular to the X axis, first and second side faces S1, S2 perpendicular to the Y axis, and first and second main faces M1, M2 perpendicular to the Z axis. The end faces E1, E2, side faces S1, S2, and main faces M1, M2 of the ceramic body 11 are all configured as flat surfaces.

In this embodiment, the flat surface does not have to be strictly planar, as long as it is recognized as flat when viewed overall. For example, it may include surfaces with minute irregularities or gently curved shapes within a specified range. The end faces E1, E2, side faces S1, S2, and main faces M1, M2 may each have portions perpendicular to the X-axis, Y-axis, and Z-axis, respectively.

The ceramic body 11 has first and second ridges R1, R2 extending along the X-axis. The first ridge R1 connects the first side surface S1 to the first main surface M1, and the second ridge R2 connects the second side surface S2 to the first main surface M1. It is preferable that the ceramic body 11 be chamfered so that the ridges R1, R2 form rounded curved surfaces.

The first principal surface M1 of the ceramic body 11 forms the lower surface in the Z-axis direction that faces the mounting substrate during mounting. The second principal surface M2 of the ceramic body 11 forms the upper surface in the Z-axis direction; that is, the second principal surface M2 is held by suction during mounting. Note that Figure 1 shows the multilayer ceramic capacitor 10 from the side of the first principal surface M1 of the ceramic body 11.

The first and second terminal electrodes 14a, 15a cover the first and second end faces E1, E2 of the ceramic body 11 and face each other in the X-axis direction with the ceramic body 11 in between. The terminal electrodes 14a, 15a extend from each end face E1, E2 of the ceramic body 11 to the main faces M1, M2 and side faces S1, S2, and are spaced apart in the X-axis direction on the main faces M1, M2 and side faces S1, S2.

The ceramic body 11 is made of dielectric ceramic. The ceramic body 11 has a plurality of first internal electrodes 12 and second internal electrodes 13 covered with dielectric ceramic. The multiple internal electrodes 12, 13 are each sheet-shaped extending along the X-Y plane and arranged alternately along the Z-axis direction.

In other words, the ceramic body 11 has an opposing region where the internal electrodes 12, 13 face each other in the Z-axis direction, sandwiching the ceramic layer therebetween. The first internal electrode 12 extends from the opposing region to the first end face E1 and is connected to the first terminal electrode 14a. The second internal electrode 13 extends from the opposing region to the second end face E2 and is connected to the second terminal electrode 15a.

With this configuration, when a voltage is applied between the first terminal electrode 14a and the second terminal electrode 15a in the multilayer ceramic capacitor 10, the voltage is applied to the multiple ceramic layers in the opposing regions of the internal electrodes 12 and 13. As a result, a charge corresponding to the voltage between the first terminal electrode 14a and the second terminal electrode 15a is stored in the multilayer ceramic capacitor 10.

The ceramic body 11 uses a dielectric ceramic with a high dielectric constant to increase the capacitance of each ceramic layer between the internal electrodes 12 and 13. Examples of the dielectric ceramic with a high dielectric constant include materials with a perovskite structure containing barium (Ba) and titanium (Ti), such as barium titanate (BaTiO ₃ ).

The dielectric ceramic may also have a composition such as strontium titanate (SrTiO ₃ ), calcium titanate (CaTiO ₃ ), magnesium titanate (MgTiO ₃ ), calcium zirconate (CaZrO 3 ), calcium titanate zirconate (Ca(Zr,Ti)O ₃ ), barium zirconate (BaZrO ₃ ), titanium oxide (TiO ₂ ), barium strontium titanate, barium calcium titanate, barium zirconate, barium titanate zirconate, calcium titanate zirconate, and barium calcium titanate zirconate (Ba _1-x-y Ca _x Sr _y Ti _1-z Zr _z O ₃ ).

In the multilayer ceramic capacitor 10, the first terminal electrode 14a is configured as part of the first external electrode unit 14 provided on the first end face E1 side of the outer surface of the ceramic body 11. The second terminal electrode 15a is configured as part of the second external electrode unit 15 provided on the second end face E2 side of the outer surface of the ceramic body 11.

The first external electrode unit 14 includes a pair of first auxiliary electrodes 14b in addition to the first terminal electrode 14a. The second external electrode unit 15 includes a pair of second auxiliary electrodes 15b in addition to the second terminal electrode 15a. Unlike the terminal electrodes 14a and 15a, the auxiliary electrodes 14b and 15b are electrodes that do not function as terminals of the multilayer ceramic capacitor 10.

The external electrode units 14, 15 can be configured as sintered films of conductive material. The sintered films of conductive material that make up the external electrode units 14, 15 can be formed by applying a conductive paste to the outer surface of the ceramic body 11 in positions corresponding to the terminal electrodes 14a, 15a and auxiliary electrodes 14b, 15b and then baking the paste.

The conductor that makes up the sintered film is typically composed primarily of Ni (nickel). However, the main component of the conductor that makes up the sintered film may also be other elements, such as Cu (copper), Pd (palladium), and Ag (silver). In this embodiment, the term "main component" refers to the component with the highest content.

The external electrode units 14, 15 may have a single-layer structure consisting of a single layer, or a multi-layer structure consisting of multiple layers. For example, the external electrode units 14, 15 may have a conductive plating layer formed by a wet plating method on a base layer consisting of a sintered film of a conductive material.

The plating layers that make up the external electrode units 14, 15 may have a single-layer structure made up of a single plating film, or a laminated structure made up of multiple plating films. As an example, the plating layer may have a laminated structure in which a Cu (copper) film, a Ni (nickel) film, and a Sn (tin) film are laminated in that order on a base layer.

The multilayer ceramic capacitor 10 can effectively prevent mounting defects caused by the tombstoning phenomenon through the action of the auxiliary electrodes 14b and 15b. In particular, the multilayer ceramic capacitor 10 can more effectively prevent mounting defects even in small, lightweight configurations where the tombstoning phenomenon is more likely to occur during mounting.

Specifically, the effect of suppressing mounting defects is more likely to be achieved effectively when the multilayer ceramic capacitor 10 is sized at or below 2.0±0.15 mm x 1.2±0.15 mm x 1.2±0.15 mm. In other words, the effect of suppressing mounting defects is more likely to be achieved effectively when the dimension in the X-axis direction is 2.0 mm or less and the dimensions in the Y-axis and Z-axis directions are 1.2 mm or less.

The size of the multilayer ceramic capacitor 10 can be, for example, 1.0±0.10 mm x 0.5±0.10 mm x 0.5±0.10 mm, 0.6±0.05 mm x 0.3±0.05 mm x 0.3±0.05 mm, or 0.2±0.015 mm x 0.1±0.015 mm x 0.1±0.015 mm. However, the multilayer ceramic capacitor 10 is not limited to these sizes and can be made in a variety of sizes depending on the application, etc.

[Auxiliary electrodes 14b, 15b]
Fig. 4 is a plan view showing the multilayer ceramic capacitor 10 from the first main surface M1 side of the ceramic body 11. Fig. 5 is a cross-sectional view of the multilayer ceramic capacitor 10 taken along line CC' in Fig. 1. That is, Fig. 5 shows a cross section passing through one auxiliary electrode 14b, 15b of the multilayer ceramic capacitor 10.

In the first external electrode unit 14, a pair of first auxiliary electrodes 14b are provided adjacent to the first terminal electrode 14a on the edges R1 and R2. Each of the pair of first auxiliary electrodes 14b is spaced apart from the first terminal electrode 14a in the X-axis direction. The pair of first auxiliary electrodes 14b also face each other with a gap in the Y-axis direction.

The pair of first auxiliary electrodes 14b each extend from edge portions R1, R2 along the first major surface M1 toward the center in the Y-axis direction. Furthermore, the pair of first auxiliary electrodes 14b each extend from edge portions R1, R2 upward in the Z-axis direction along side surfaces S1, S2. As a result, the cross section of each first auxiliary electrode 14b parallel to the Y-Z plane is L-shaped.

In the second external electrode unit 15, a pair of second auxiliary electrodes 15b are provided at positions adjacent to the second terminal electrode 15a on the edges R1 and R2. Each of the pair of second auxiliary electrodes 15b is spaced apart from the second terminal electrode 15a in the X-axis direction. The pair of second auxiliary electrodes 15b also face each other with a gap in the Y-axis direction.

The pair of second auxiliary electrodes 15b each extend from the ridges R1 and R2 along the first major surface M1 toward the center in the Y-axis direction. The pair of second auxiliary electrodes 15b also extend from the ridges R1 and R2 upward in the Z-axis direction along the side surfaces S1 and S2. This results in each second auxiliary electrode 15b having an L-shaped cross section parallel to the Y-Z plane.

Figure 6 is a side view showing a circuit board 100 on which a multilayer ceramic capacitor 10 is mounted. The circuit board 100 includes a mounting substrate 20 having a substrate main body 21, a first terminal 22, and a second terminal 23. The terminals 22 and 23 form a pair of terminals of the mounting substrate 20 and are provided on the mounting surface of the substrate main body 21 facing upward in the Z-axis direction.

On the circuit board 100, the external electrode units 14, 15 of the multilayer ceramic capacitor 10 are soldered to the terminals 22, 23 of the mounting substrate 20, respectively. As a result, on the circuit board 100, the multilayer ceramic capacitor 10 is electrically connected to and physically fixed to the mounting substrate 20.

A typical reflow method can be used to mount the multilayer ceramic capacitor 10 on the mounting substrate 20. In the reflow method, the external electrode units 14, 15 of the multilayer ceramic capacitor 10 are placed on the terminals 22, 23 of the mounting substrate 20, on which solder H is arranged, and the solder H is melted and then solidified during the process of passing through a reflow furnace.

As a result, on the first terminal 22 of the mounting substrate 20, the molten solder H spreads substantially simultaneously to the adjacent first terminal electrode 14a and first auxiliary electrode 14b. Furthermore, on the second terminal 23 of the mounting substrate 20, the molten solder H spreads substantially simultaneously to the adjacent second terminal electrode 15a and second auxiliary electrode 15b.

In this way, in the multilayer ceramic capacitor 10, the terminal electrodes 14a, 15a and the auxiliary electrodes 14b, 15b can be soldered to the terminals 22, 23 together. Therefore, in the multilayer ceramic capacitor 10, no additional work is required to solder the auxiliary electrodes 14b, 15b to the terminals 22, 23 of the mounting substrate 20.

By providing auxiliary electrodes 14b and 15b in the multilayer ceramic capacitor 10, it is possible to prevent the occurrence of tombstone formation, which occurs on one of the terminals 22 and 23 due to the surface tension of the molten solder H. The function of the auxiliary electrodes 14b and 15b in the multilayer ceramic capacitor 10 is explained below.

Figure 7 is a side view showing the process of mounting a multilayer ceramic capacitor 10a according to a comparative example of this embodiment. The multilayer ceramic capacitor 10a according to the comparative example is provided with terminal electrodes 14a and 15a, but differs from the multilayer ceramic capacitor 10 according to this embodiment in that it does not have auxiliary electrodes 14b and 15b.

The multilayer ceramic capacitor 10a shown in Figure 7 exhibits a tombstone phenomenon in which a rising edge occurs on the second terminal 23 of the mounting substrate 20. This tombstone phenomenon occurs because a moment is generated in the direction indicated by the arrow in Figure 7 due to the surface tension of the solder H, which has spread to the second terminal electrode 15a before spreading to the first terminal electrode 14a.

In the multilayer ceramic capacitor 10a shown in Figure 7, the tombstoning phenomenon causes the first terminal electrode 14a to lift off the first terminal 22 of the mounting substrate 20, resulting in a loss of electrical continuity between the first terminal electrode 14a and the first terminal 22 of the mounting substrate 20. Therefore, the multilayer ceramic capacitor 10a shown in Figure 7 is defective in mounting.

Furthermore, in the multilayer ceramic capacitor 10a, even if the solder H spreads to the first terminal electrode 14a before spreading to the second terminal electrode 15a, a tombstone phenomenon occurs in which the solder H rises up on the first terminal 22 of the mounting substrate 20. As such, the multilayer ceramic capacitor 10a according to the comparative example is prone to mounting defects due to the tombstone phenomenon.

In contrast, in the multilayer ceramic capacitor 10 according to this embodiment, the surface tension of the solder H acts on the auxiliary electrodes 14b and 15b to prevent them from rising up on the terminals 22 and 23 of the mounting substrate 20. This makes it possible to suppress the occurrence of tombstoning in the multilayer ceramic capacitor 10.

In other words, in the first external electrode unit 14, the surface tension of the solder H acts on the first auxiliary electrode 14b in the opposite direction to the force acting on the first terminal electrode 14a to cause the multilayer ceramic capacitor 10 to stand up on the first terminal 22. This makes it difficult for the multilayer ceramic capacitor 10 to stand up on the first terminal 22.

Furthermore, in the second external electrode unit 15, the surface tension of the solder H acts on the second auxiliary electrode 15b in the opposite direction to the force acting on the second terminal electrode 15a that tends to cause the multilayer ceramic capacitor 10 to stand up on the second terminal 23. This makes it difficult for the multilayer ceramic capacitor 10 to stand up on the second terminal 23.

For this reason, in the multilayer ceramic capacitor 10, even if the solder H spreads before one of the external electrode units 14, 15, the tombstone phenomenon is unlikely to occur, and the multilayer ceramic capacitor 10 is likely to maintain a normal posture on the mounting substrate 20 during the mounting process. Therefore, the occurrence of mounting defects can be reduced in the multilayer ceramic capacitor 10.

In the multilayer ceramic capacitor 10, by locating the auxiliary electrodes 14b, 15b away from the terminal electrodes 14a, 15a, respectively, the effect of the surface tension of the solder H acting on the auxiliary electrodes 14b, 15b is more likely to be stable. This makes it possible to more effectively suppress the occurrence of tombstoning in the multilayer ceramic capacitor 10.

Furthermore, as shown in Figure 8, in the multilayer ceramic capacitor 10, the portions of the terminal electrodes 14a, 15a that extend onto the first principal surface M1 tend to bulge inward in the X-axis direction at the center in the Y-axis direction. This is due to the fluidity of the conductive paste on the ceramic body 11 that is used to form the terminal electrodes 14a, 15a.

In other words, on the outer surface of the ceramic body 11, the fluidity of the conductive paste in the X-axis direction is higher at the center of the first main surface M1 in the Y-axis direction than at the ridges R1 and R2. As a result, the terminal electrodes 14a and 15a extend further at the center of the first main surface M1 in the Y-axis direction than at the ridges R1 and R2, making it easier for them to have the bulging shape described above.

In this regard, in the multilayer ceramic capacitor 10, auxiliary electrodes 14b, 15b are provided only at four locations near the edges R1, R2 of the terminal electrodes 14a, 15a on the outer surface of the ceramic body 11, where the extension inward in the X-axis direction is small. Therefore, in the multilayer ceramic capacitor 10, the auxiliary electrodes 14b, 15b can be positioned closer to the end faces E1, E2.

Therefore, in the multilayer ceramic capacitor 10, the spacing between the auxiliary electrodes 14b, 15b in the X-axis direction can be increased by the amount that the auxiliary electrodes 14b, 15b are moved closer to the end faces E1, E2. This makes it possible to prevent poor moisture resistance due to migration between the auxiliary electrodes 14b, 15b in the multilayer ceramic capacitor 10.

Furthermore, in the multilayer ceramic capacitor 10, the auxiliary electrodes 14b, 15b are provided only in four locations near the edges R1, R2, which allows the auxiliary electrodes 14b, 15b to be made smaller. This allows the area on the outer surface of the ceramic body 11 where conductive paste is applied to form the external electrode units 14, 15 to be reduced.

As a result, even in processes where multiple ceramic bodies 11 are handled simultaneously, such as firing to bake the conductive paste, the probability of the conductive paste on adjacent ceramic bodies 11 coming into contact with each other can be reduced. This makes it possible to prevent adhesion problems, such as the external electrode units 14, 15 of multiple multilayer ceramic capacitors 10 adhering to each other.

In addition, even in a multilayer ceramic capacitor 10 in which the auxiliary electrodes 14b, 15b are small, by extending the auxiliary electrodes 14b, 15b from the ridges R1, R2 to the first principal surface M1 and side surfaces S1, S2, it is possible to fully and accurately obtain the above-described effect of the surface tension of the solder H on the auxiliary electrodes 14b, 15b.

[Dimensions of external electrode units 14, 15]
4 and 5 show the following dimensions of the external electrode units 14, 15. "L0" indicates the length of each terminal electrode 14a, 15a in the X-axis direction. "W0" indicates the width of each terminal electrode 14a, 15a in the Y-axis direction. "T0" indicates the thickness of each terminal electrode 14a, 15a in the Z-axis direction on the first main surface M1.

Furthermore, "L" indicates the length in the X-axis direction of each auxiliary electrode 14b, 15b in each external electrode unit 14, 15. "W" indicates the width in the Y-axis direction of each auxiliary electrode 14b, 15b in each external electrode unit 14, 15. "T" indicates the thickness in the Z-axis direction of each auxiliary electrode 14b, 15b on the first main surface M1 in each external electrode unit 14, 15.

Furthermore, "D1" indicates the distance in the X-axis direction between the first auxiliary electrode 14b and the second auxiliary electrode 15b. "D2" indicates the distance in the X-axis direction between the terminal electrodes 14a, 15a and the auxiliary electrodes 14b, 15b in each external electrode unit 14, 15. "D3" indicates the distance in the Y-axis direction between the first auxiliary electrodes 14b and between the second auxiliary electrodes 15b.

It is anticipated that the above dimensions of the multilayer ceramic capacitor 10 may not be constant across the entire range. In such cases, the lengths L0 and L, widths W0 and W, and thicknesses T0 and T will be defined as the maximum values of each dimension. Furthermore, the spacings D1, D2, and D3 will be defined as the minimum values of each dimension.

The distance D1 between the auxiliary electrodes 14b and 15b in the X-axis direction is preferably 160% or more of the dimension L0 of the terminal electrodes 14a and 15a in the X-axis direction. This makes it possible to more effectively prevent poor moisture resistance due to migration between the auxiliary electrodes 14b and 15b in the multilayer ceramic capacitor 10.

The distance D2 in the X-axis direction between the terminal electrode 14a, 15a and the auxiliary electrode 14b, 15b in each external electrode unit 14, 15 is preferably 2% or more of the dimension L0 in the X-axis direction of the terminal electrode 14a, 15a. This allows the auxiliary electrodes 14b, 15b to be more stably affected by the surface tension of the solder H.

Furthermore, it is preferable that the distance D2 in the X-axis direction between the terminal electrode 14a, 15a and the auxiliary electrode 14b, 15b in each external electrode unit 14, 15 be 10% or less of the dimension L0 in the X-axis direction of the terminal electrode 14a, 15a. This makes it easier to collectively solder the terminal electrodes 14a, 15a and auxiliary electrodes 14b, 15b to the terminals 22, 23 of the mounting substrate 20.

The distance D3 in the Y-axis direction between the auxiliary electrodes 14b, 15b in each external electrode unit 14, 15 is preferably 40% or more of the dimension W0 in the Y-axis direction of the terminal electrodes 14a, 15a. This allows the auxiliary electrodes 14b, 15b to be positioned closer to the end faces E1, E2.

In each external electrode unit 14, 15, the length L in the X-axis direction of each auxiliary electrode 14b, 15b is preferably 2% or more of the length L0 in the X-axis direction of the terminal electrode 14a, 15a. This allows the auxiliary electrodes 14b, 15b to be more effectively affected by the surface tension of the solder H.

Furthermore, in each external electrode unit 14, 15, the length L in the X-axis direction of each auxiliary electrode 14b, 15b is preferably 10% or less of the length L0 in the X-axis direction of the terminal electrode 14a, 15a. This makes it easier to ensure a large distance D1 in the X-axis direction between the auxiliary electrodes 14b, 15b, and also enables the auxiliary electrodes 14b, 15b to be made smaller.

In each external electrode unit 14, 15, the width W in the Y-axis direction of each auxiliary electrode 14b, 15b is preferably 1% or more of the width W0 in the Y-axis direction of the terminal electrode 14a, 15a. This allows the auxiliary electrodes 14b, 15b to be more effectively affected by the surface tension of the solder H.

Furthermore, in each external electrode unit 14, 15, the width W in the Y-axis direction of each auxiliary electrode 14b, 15b is preferably 100 μm or less and 10% or less of the width W0 in the Y-axis direction of the terminal electrode 14a, 15a. This allows the auxiliary electrodes 14b, 15b to be positioned closer to the end faces E1, E2, and also allows the auxiliary electrodes 14b, 15b to be made smaller.

In each external electrode unit 14, 15, the thickness T in the Z-axis direction of the auxiliary electrodes 14b, 15b is preferably 10% to 100% of the thickness T0 in the Z-axis direction of the terminal electrodes 14a, 15a. This makes it easier to collectively solder the terminal electrodes 14a, 15a and auxiliary electrodes 14b, 15b to the terminals 22, 23 of the mounting substrate 20.

[Examples and Comparative Examples]
As examples of the above embodiment, samples of the multilayer ceramic capacitor 10 were fabricated in which the dimensions of the external electrode units 14, 15 were variously changed. Furthermore, as comparative examples of the above embodiment, samples were fabricated in which the auxiliary electrodes 14b, 15b were eliminated from the multilayer ceramic capacitor 10 according to the above embodiment.

In both the samples according to the example and the comparative example, the dimension in the X-axis direction was 2.0 mm, and the dimensions in the Y-axis and Z-axis directions were 1.2 mm. In addition, in both the samples according to the example and the comparative example, the length L0 of the terminal electrodes 14a, 15a in the X-axis direction was 0.52 mm, and the width W0 of the terminal electrodes 14a, 15a in the Y-axis direction was 1.2 mm.

In each example and comparative example, the conductive paste was baked onto multiple ceramic bodies 11 at once, and the adhesion failure rate, which is the proportion of samples with poor adhesion where the external electrode units 14, 15 were stuck to each other, was determined. In each example and comparative example, 10,000 samples were baked at once to determine the adhesion failure rate.

In addition, for each example and comparative example, a number of properly manufactured samples were mounted on a mounting substrate 20 by the reflow method, and the mounting defect rate, which is the percentage of samples in which the tombstone phenomenon occurred, was determined. For each example and comparative example, the mounting defect rate was determined by mounting 800 samples on a mounting substrate 20.

Furthermore, for each example and comparative example, the moisture resistance defect rate was determined, which is the percentage of circuit boards on which samples were properly mounted that had an electrical resistance of less than 1 MΩ after being held at a temperature of 60°C, humidity of 95%, and a rated voltage of 10 V applied. For each example and comparative example, the moisture resistance defect rate was determined using 800 circuit boards.

Table 1 shows the dimensions of the external electrode units 14, 15, the adhesion defect rate, the mounting defect rate, and the moisture resistance defect rate for Examples 1 to 5 and the comparative example. For the samples of Examples 1 to 5, the length L of the auxiliary electrodes 14b, 15b in the X-axis direction was varied, meaning that the ratio of length L1 to length L0 was different.

No adhesion failures occurred in any of Examples 1 to 5 or the Comparative Example. Furthermore, no mounting failures occurred in any of Examples 1 to 5, whereas mounting failures occurred in the Comparative Example. Furthermore, no moisture resistance failures occurred in Examples 1 to 3 and the Comparative Example, whereas moisture resistance failures occurred in Examples 4 and 5.

The results of the mounting defect rate show that the occurrence of tombstoning was suppressed more in Examples 1 to 5, which included auxiliary electrodes 14b and 15b, than in the comparative example. Furthermore, the results of the moisture resistance defect rate show that Examples 1 to 3, in which the ratio of length L1 to length L0 was 10% or less, had higher moisture resistance than Examples 4 and 5, in which the ratio of length L1 to length L0 exceeded 10%.

Table 2 shows the dimensions of the external electrode units 14, 15, the adhesion failure rate, the mounting failure rate, and the moisture resistance failure rate for Examples 2, 6, and 7. In Examples 2, 6, and 7, the width W of the auxiliary electrodes 14b, 15b in the Y-axis direction in the samples was varied, but no adhesion failure, mounting failure, or moisture resistance failure occurred in any of the samples.

[Other embodiments]
Although the embodiments of the present invention have been described above, it goes without saying that the present invention is not limited to the above-described embodiments and that various modifications can be made.

For example, the multilayer ceramic capacitor 10 is not limited to a configuration in which the auxiliary electrodes 14b, 15b are provided only on the first principal surface M1, but may also be provided on both principal surfaces M1 and M2. This eliminates the need to consider the orientation of the multilayer ceramic capacitor 10 in the Z-axis direction when mounting the multilayer ceramic capacitor 10 on the mounting substrate 20.

Furthermore, in the multilayer ceramic capacitor 10, it is sufficient that the terminal electrodes 14a, 15a extend onto the first main surface M1; if the auxiliary electrodes 14b, 15b are not provided on the second main surface M2, the terminal electrodes 14a, 15a do not have to extend onto the second main surface M2. Furthermore, the terminal electrodes 14a, 15a do not have to extend onto the side surfaces S1, S2.

Furthermore, the external electrode units 14, 15 do not have to include a sintered film of a conductive material, and may instead include, for example, a sputtered film formed by sputtering a metal material as a base film. Even in this case, the multilayer ceramic capacitor 10 still achieves the effect of suppressing the occurrence of tombstoning due to the auxiliary electrodes 14b, 15b.

In addition, the present invention is applicable not only to multilayer ceramic capacitors, but also to ceramic electronic components in general that have a pair of terminal electrodes. In addition to multilayer ceramic capacitors, examples of ceramic electronic components to which the present invention can be applied include chip varistors, chip thermistors, and multilayer inductors.

10... Multilayer ceramic capacitor 11... Ceramic body 12, 13... Internal electrodes 14, 15... External electrode units 14a, 15a... Terminal electrodes 14b, 15b... Auxiliary electrodes E1, E2... End surfaces S1, S2... Side surfaces M1, M2... Main surfaces R1, R2... Ridge portions

Claims (6)

a ceramic body having first and second main surfaces perpendicular to a first axis, first and second end surfaces perpendicular to a second axis orthogonal to the first axis, first and second side surfaces perpendicular to a third axis orthogonal to the first and second axes, and first and second ridge portions connecting the first and second side surfaces to the first main surfaces, respectively;
a first external electrode unit provided on the first end surface side of the ceramic body;
a second external electrode unit provided on the second end surface side of the ceramic body;
Equipped with
the first external electrode unit includes a first terminal electrode covering the first end surface and extending from the first end surface to the first main surface, and a pair of first auxiliary electrodes spaced apart from the first terminal electrode and spaced apart from each other, extending from the first and second ridge portions along the first main surface in the third axis direction; the second external electrode unit includes a second terminal electrode covering the second end surface and extending from the second end surface to the first main surface, and a pair of second auxiliary electrodes spaced apart from the second terminal electrode and spaced apart from each other, extending from the first and second ridge portions along the first main surface in the third axis direction ;
when the first main surface is viewed from the front, approximately central portions of the first and second terminal electrodes in the direction of the third axis bulge toward a center of the ceramic body in the direction of the second axis,
an edge of each of the pair of first auxiliary electrodes on the first end surface side is closer to the first end surface in the direction of the second axis than an apex of the bulge at the approximately central portion of the first terminal electrode;
an edge of each of the pair of second auxiliary electrodes on the second end surface side is closer to the second end surface in the second axis direction than an apex of the bulge at the approximately central portion of the second terminal electrode;
Ceramic electronic components. 2. The ceramic electronic component according to claim 1,
The ceramic electronic component, wherein the first terminal electrode, the pair of first auxiliary electrodes, the second terminal electrode, and the pair of second auxiliary electrodes include sintered films of a conductor. 3. The ceramic electronic component according to claim 1,
the pair of first auxiliary electrodes extend in the first axis direction from the first and second edge portions along the first and second side surfaces, respectively;
The pair of second auxiliary electrodes extend in the first axial direction from the first and second edge portions along the first and second side surfaces, respectively. 4. The ceramic electronic component according to claim 1,
a dimension of the pair of first auxiliary electrodes in the second axis direction is 2% to 10% of a dimension of the first terminal electrode in the second axis direction,
The ceramic electronic component, wherein the dimension of the pair of second auxiliary electrodes in the second axial direction is 2% to 10% of the dimension of the second terminal electrode in the second axial direction. 4. The ceramic electronic component according to claim 1,
a distance between the first terminal electrode and the pair of first auxiliary electrodes is 2% or more and 10% or less of a dimension of the first terminal electrode in the second axis direction,
a distance between the second terminal electrode and the pair of second auxiliary electrodes that is equal to or greater than 2% and equal to or less than 10% of a dimension of the second terminal electrode in the second axis direction; a ceramic body having first and second main surfaces perpendicular to a first axis, first and second end surfaces perpendicular to a second axis orthogonal to the first axis, first and second side surfaces perpendicular to a third axis orthogonal to the first and second axes, and first and second ridge portions connecting the first and second side surfaces to the first main surfaces, respectively;
a first external electrode unit provided on the first end surface side of the ceramic body;
a second external electrode unit provided on the second end surface side of the ceramic body;
Equipped with
a ceramic electronic component in which the first external electrode unit includes: a first terminal electrode covering the first end surface and extending from the first end surface to the first main surface; and a pair of first auxiliary electrodes spaced apart from the first terminal electrode and spaced apart from each other, extending from the first and second ridge portions along the first main surface in the third axis direction; and the second external electrode unit includes: a second terminal electrode covering the second end surface and extending from the second end surface to the first main surface; and a pair of second auxiliary electrodes spaced apart from the second terminal electrode and spaced apart from each other, extending from the first and second ridge portions along the first main surface in the third axis direction.
a mounting substrate including: a substrate body; a first terminal provided on the substrate body and having the first terminal electrode and the first auxiliary electrode soldered thereto; and a second terminal provided on the substrate body and having the second terminal electrode and the second auxiliary electrode soldered thereto;
Equipped with
when the first main surface is viewed from the front, approximately central portions of the first and second terminal electrodes in the direction of the third axis bulge toward a center of the ceramic body in the direction of the second axis,
an edge of each of the pair of first auxiliary electrodes on the first end surface side is closer to the first end surface in the direction of the second axis than an apex of the bulge at the approximately central portion of the first terminal electrode;
an edge of each of the pair of second auxiliary electrodes on the second end surface side is closer to the second end surface in the second axis direction than an apex of the bulge at the approximately central portion of the second terminal electrode;
Circuit board.