JP4561754B2 - Multilayer capacitor - Google Patents

Description

  The present invention relates to a multilayer capacitor.

As this type of multilayer capacitor, a capacitor including an element body made of a dielectric material, a plurality of internal electrodes formed in the element body, and a pair of terminal electrodes formed so as to cover both side surfaces of the element body. It is known (see, for example, Patent Document 1).
Japanese Patent Laid-Open No. 9-148174

  When a voltage is applied to the above-described multilayer capacitor, mechanical distortion having a magnitude corresponding to the applied voltage may occur in the element body due to the electrostrictive effect. In particular, when an AC voltage is applied, vibration is generated in the multilayer capacitor due to this mechanical strain. Therefore, when a multilayer capacitor is mounted on a substrate and an AC voltage is applied, the vibration of the multilayer capacitor propagates to the substrate and a so-called sound is generated.

  Therefore, an object of the present invention is to provide a multilayer capacitor capable of suppressing noise generated when mounted on a substrate or the like.

  The inventor has intensively studied to reduce the noise generated when the multilayer capacitor is mounted on a substrate or the like. As a result, the present inventor obtains knowledge that the squeal occurs at the contact portion between the substrate and the multilayer capacitor on which the multilayer capacitor is mounted, that is, the contact portion between the land electrode of the substrate and the terminal electrode of the multilayer capacitor. It came.

  Based on such examination results, the multilayer capacitor according to the present invention includes an element body made of a dielectric material, a plurality of internal electrodes arranged in the element body so that at least a part thereof faces each other, and an element body disposed on the element body. Each of the plurality of internal electrodes is either one of a pair of side surfaces that are parallel to a first direction of the outer surface of the element body and that are parallel to each other and facing each other. The pair of terminal electrodes has a first electrode portion and a second electrode portion continuous with the first electrode portion, and one of the pair of terminal electrodes has one of the pair of terminal electrodes. The first and second electrode portions are arranged on one side surface of the pair of side surfaces, and the first and second electrode portions of the other terminal electrode of the pair of terminal electrodes are the other side surface of the pair of side surfaces. One terminal electrode The first electrode portion covers an exposed portion exposed on one side surface, the second electrode portion of one terminal electrode extends toward an edge intersecting the first direction on one side surface, and the other terminal The first electrode portion of the electrode covers the exposed portion exposed on the other side surface, the second electrode portion of the other terminal electrode extends toward the edge intersecting the first direction of the other side surface, In the second direction orthogonal to the first direction and the direction in which the pair of side surfaces oppose each other, the length of the second electrode portion of one terminal electrode is compared with the length of the exposed portion exposed on one side surface. It is set so that it may become small.

  In the multilayer capacitor according to the present invention, one terminal electrode includes a first electrode portion covering the exposed portion of the internal electrode, and an edge portion that is continuous with the first electrode portion and intersects the first direction of one side surface. And a second electrode portion extending in the direction. In the second direction, the length of the second electrode portion is smaller than the length of the exposed portion of the internal electrode. Since the exposed part of the internal electrode is covered with the first electrode part, the length of the second electrode part in the second direction is compared with the length of the first electrode part covering the exposed part of the internal electrode. Even small. That is, in the multilayer capacitor according to the present invention, the second electrode portion of one terminal electrode is thinner than the first electrode portion. When this second electrode portion is connected to the land electrode of the substrate, the terminal electrode and the terminal electrode formed so as to cover the entire side surface of the element body are connected to the land electrode of the substrate. The contact area with the substrate is reliably reduced. By narrowing the contact area between the terminal electrode and the land electrode of the substrate, it is possible to effectively suppress the propagation of vibration due to the multilayer capacitor to the substrate. Therefore, according to the multilayer capacitor in accordance with the present invention, it is possible to reduce squeal when mounted on a substrate. In the multilayer capacitor according to the present invention, the exposed portion of the internal electrode in the second direction can be sufficiently long, so that the exposed portion of the internal electrode and the first electrode portion can be reliably brought into contact with each other. . Therefore, poor contact between the internal electrode and the terminal electrode can be suppressed.

  In the multilayer capacitor of the present invention, the length of the second electrode portion of the other terminal electrode is set to be smaller than the length of the exposed portion exposed on the other side surface in the second direction. It is preferable that In this case, since the contact area between the other terminal electrode and the substrate is also reduced, the vibration of the multilayer capacitor is more difficult to be transmitted to the substrate. Therefore, it is possible to further reduce the noise when mounted on a substrate or the like.

  In the multilayer capacitor of the present invention, in the second direction, the length of the first electrode portion of one terminal electrode is set to be larger than the length of the exposed portion exposed on one side surface. The length of the first electrode portion of the other terminal electrode is preferably set to be larger than the length of the exposed portion exposed on the other side surface. In this case, since the exposed portion of the internal electrode is reliably covered with the first electrode portion, the multilayer capacitor can be excellent in moisture resistance.

  In the multilayer capacitor of the present invention, the pair of terminal electrodes are disposed on the side surface orthogonal to the first direction on the outer surface of the element body, and are continuous with the second electrode portion and are second in the second direction. It is preferable to further include a third electrode portion having the same length as each of the two electrode portions. In this case, since the electrode portion is also disposed on the side surface orthogonal to the first direction, it becomes easier to connect the land electrode of the substrate and the terminal electrode of the multilayer capacitor.

In the multilayer capacitor of the present invention, in each of the pair of terminal electrodes, the length W1 in the second direction of the second and third electrode portions and the side surface of the element body on which the third electrode portion is disposed The length T1 in the first direction to the internal electrode disposed closest to the side surface is:
0.4 <W1 / T1 <8
It is preferable to satisfy | fill the relational expression represented by these. Of the element body, the electrostrictive effect is generated between the internal electrodes. By setting W1 / T1 to less than 8, even if an electrostrictive effect occurs in the portion sandwiched between the internal electrodes and mechanical distortion occurs in the element body, the third electrode part is pulled by the distorted element body. Is less likely to occur. Therefore, it is possible to further reduce the noise generated when the multilayer capacitor is mounted on a substrate or the like. Further, by making W1 / T1 larger than 0.4, it is possible to prevent a contact failure from occurring when the third electrode portion is connected to a land electrode or the like of the substrate.

  ADVANTAGE OF THE INVENTION According to this invention, the multilayer capacitor which can suppress the noise generated when it mounts on a board | substrate etc. can be provided.

  Hereinafter, preferred embodiments will be described in detail with reference to the accompanying drawings. In the description, the same reference numerals are used for the same elements or elements having the same function, and redundant description is omitted.

  Based on FIG.1 and FIG.2, the structure of the multilayer capacitor C1 which concerns on this embodiment is demonstrated. 1A and 1B are diagrams of the multilayer capacitor according to the present embodiment, in which FIG. 1A is a perspective view and FIG. 1B is a side view. FIG. 2 is a cross-sectional view of the multilayer capacitor in accordance with the present embodiment.

  As shown in FIGS. 1 and 2, the multilayer capacitor C <b> 1 includes a capacitor body (element body) 2, a plurality (12 layers in this embodiment) of internal electrodes E, and a pair of terminal electrodes 4 and 6. ing.

  The capacitor body 2 has a substantially rectangular parallelepiped shape, and is opposed to the first side surface 2a and the second side surface 2b facing each other and parallel to the direction of the arrow A (first direction) and the first and second side surfaces. The third side surface 2c and the fourth side surface 2d that are continuous to the two side surfaces 2a and 2b and orthogonal to the direction of the arrow A, and that face each other and are continuous to the first to fourth side surfaces 2a to 2d and the direction of the arrow A A fifth side surface 2e and a sixth side surface 2f which are parallel to each other. Here, the arrow A direction indicates the direction in which the internal electrodes E1 and E2 face each other. 1 indicates a direction in which the first and second side surfaces 2a and 2b face each other, and an arrow C (second direction) indicates a direction orthogonal to the arrow A direction and the arrow B direction. .

  The capacitor body 2 is made of a dielectric material, and an internal electrode E is disposed inside the capacitor body 2. As shown in FIG. 2, the internal electrode E is composed of six E1s and six E2. The internal electrodes E1 and E2 are alternately stacked so that at least a part of the internal electrodes E1 and E2 face each other with the dielectric layer 3 interposed therebetween. As shown in FIG. 1B, one end of the internal electrode E1 is exposed on the first side surface 2a, and one end (not shown) of the internal electrode E2 is exposed on the second side surface 2b. . Hereinafter, one end portion of the internal electrode E1 exposed on the first side surface 2a is referred to as “exposed portion 7 of the internal electrode E1”, and one end portion of the internal electrode E2 exposed on the second side surface 2b is referred to as “exposed internal electrode E2”. Called “part”. The exposed portion 7 of the internal electrode E1 and the exposed portion of the internal electrode E2 have the same shape and size. The dielectric layer 3 of the internal electrode E1 is made of, for example, a sintered body of a ceramic green sheet containing a dielectric ceramic. The internal electrodes E1, E2 are composed of a sintered body of conductive paste.

  Terminal electrodes 4 and 6 are arranged on the capacitor body 2. The terminal electrode 4 has electrode portions 4a, 4b, 4c, 4d, and 4e, and the terminal electrode 6 has electrode portions 6a, 6b, 6c, 6d, and 6e. The terminal electrode 4 and the terminal electrode 6 have the same shape and size. The terminal electrodes 4 and 6 are formed, for example, by baking a conductive paste containing conductive metal powder and glass frit on the corresponding outer surface of the capacitor body 2. If necessary, a plating layer may be formed on the baked electrode. Further, it may be formed by printing.

  As shown in FIG.1 (b), the electrode part (1st electrode part) 4a-4c of the terminal electrode 4 is arrange | positioned at the 1st side surface 2a. The electrode portion 4a covers the exposed portion 7 of the internal electrode E1. The electrode portions (second electrode portions) 4b and 4c of the terminal electrode 4 are respectively continuous with the electrode portion 4a and extend toward the edge of the first side surface 2a that intersects the arrow A direction. . More specifically, the electrode portion 4b extends from the electrode portion 4a in the direction of the arrow A and reaches the edge of the first side surface 2a located on the third side surface 2c side. The electrode portion 4c extends from the electrode portion 4a in the direction of arrow A and reaches the edge of the first side surface 2a located on the fourth side surface 2d side. An electrode portion (third electrode portion) 4d of the terminal electrode 4 is disposed on the third side surface 2c and continues to the electrode portion 4b. The electrode portion (third electrode portion) 4e is disposed on the fourth side surface 2d and continues to the electrode portion 4c. The electrode parts 4b-4e have the same length in the arrow C direction.

  If the length of the electrode parts 4b to 4e in the arrow C direction is W1, the length of the electrode part 4a in the arrow C direction is W2, and the length of the exposed part 7 of the internal electrode E1 in the arrow C direction is W3, the electrode part 4b The length W1 of ˜4e is smaller than the length W3 of the exposed portion 7 of the internal electrode E1. In addition, the length W2 of the electrode portion 4a is larger than the length W3 of the exposed portion 7 of the internal electrode E1. As can be seen from these, the length W1 of the electrode portions 4b to 4e is smaller than the length W2 of the electrode portion 4a. Therefore, the terminal electrode 4 has a substantially cross shape on the first side surface 2a.

  As shown in FIG. 2, in the direction of arrow A, from the side surface on which the electrode portion 4d is disposed, that is, from the third side surface 2c to the internal electrode E (E2 in FIG. 2) disposed closest to the third side surface 2c. The length T1 and the length W1 of the electrode portion 4b satisfy the following relational expression (1).

  0.4 <W1 / T1 <8 (1)

  The basis of the above formula (1) will be described. In order to study the preferable range of W1 / T1, the present inventors prepare a plurality of multilayer capacitors C1 having different W1 / T1 and use the electrode portions 4d and 6d of the prepared multilayer capacitors C1 as land electrodes of the substrate. A voltage was applied in connection with. When the deformation amount of the substrate at the time of voltage application was measured, the result shown in FIG. 3 was obtained, and it was found that when W1 / T1 was made larger than 8, the deformation amount of the substrate exceeded 5 nm. Further, it was found that when W1 / T1 is smaller than 0.4, the contact area between the electrode portions 4d and 6d and the land electrode of the substrate becomes too small, and it becomes difficult to apply a voltage. From the above, it has been found that it is sufficient to satisfy the formula (1) in order to prevent the contact failure between the electrode portions 4d and 6d and the substrate during mounting and reduce the deformation amount of the substrate. .

  In the direction of arrow A, the length from the side surface where the electrode portion 4e is disposed, that is, the length from the fourth side surface 2d to the internal electrode E (E1) disposed closest to the fourth side surface 2d is the third length. The length is the same as the length from the side surface 2c to the internal electrode E (E2) disposed closest to the third side surface 2c. Therefore, the length from the fourth side surface 2d to the internal electrode E disposed closest to the fourth side surface 2d can also be expressed as T1.

  Electrode portions (first electrode portions) 6a to 6c of the terminal electrode 6 are disposed on the second side surface 2b. The electrode portion 6a covers an exposed portion (not shown) of the internal electrode E2. The electrode portions (second electrode portions) 6b and 6c are respectively continuous with the electrode portion 6a, and the electrode portion 6b extends from the electrode portion 6a in the direction of arrow A and is located on the third side surface 2c side. It reaches the edge of the side surface 2b. The electrode portion 6c extends in the arrow A direction from the electrode portion 6a and reaches the edge of the second side surface 2b located on the fourth side surface 2d side. The electrode portion (third electrode portion) 6d is continuous with the electrode portion 6b and is disposed on the third side surface 2c. An electrode portion (third electrode portion) 6e of the terminal electrode 6 is continuous with the electrode portion 6c and is disposed on the fourth side surface 2d.

  As described above, the terminal electrode 6 has the same shape and dimensions as the terminal electrode 4. Therefore, the length of the electrode portions 6b to 6e in the direction of the arrow C can be expressed as W1 similarly to the electrode portions 4b to 4e. About the length of the electrode part 6a in the arrow C direction, it can represent with W2 similarly to the electrode part 4a. Since the exposed portion of the internal electrode E2 has the same dimensions as the exposed portion 7 of the internal electrode E1, the length of the exposed portion of the internal electrode E2 in the direction of arrow C is the same as that of the exposed portion 7 of the internal electrode E1. Can be expressed as W3. The terminal electrode 6 has a substantially cross shape on the second side surface 2b.

  When the multilayer capacitor C1 having the above configuration is mounted on the substrate, the electrode portions 4d and 6d of the terminal electrodes 4 and 6 are connected to the land electrode of the substrate. In the terminal electrodes 4 and 6, the length W1 of the electrode portions 4b to 4e and 6b to 6e is smaller than the length W2 of the electrode portions 4a and 6a. That is, the electrode portions 4b to 4e and 6b to 6e are thinner than the electrode portions 4a and 6a. By connecting the thin electrode portions 4d and 6d to the land electrode of the substrate in this way, the contact area between the terminal electrodes 4 and 6 and the land electrode of the substrate can be reduced. After connecting the electrode portions 4d and 6d to the land electrodes of the substrate and then applying a voltage to the internal electrodes E1 and E2 via the terminal electrodes 4 and 6, an electrostrictive effect is generated in the portion sandwiched between the internal electrodes E1 and E2. To do. Due to the electrostrictive effect, mechanical distortion occurs in the capacitor body 2 and vibration is generated in the multilayer capacitor C1. However, since the contact area between the terminal electrodes 4 and 6 and the substrate is small, the vibration is generated in the substrate. Propagation to can be effectively suppressed. Therefore, it is possible to reduce the noise generated when the multilayer capacitor C1 is mounted on a substrate or the like.

  In the multilayer capacitor C1, the length W3 of the exposed portions of the internal electrodes E1 and E2 is larger than the length W1 of the electrode portions 4b to 4e and 6b to 6e. can do. Thereby, the exposed part of internal electrode E1, E2 and electrode part 4a, 6a can be made to contact reliably. As a result, poor contact is less likely to occur between the internal electrodes E1, E2 and the terminal electrodes 4, 6.

  In the multilayer capacitor C1, the length W2 of the electrode portions 4a and 6a is larger than the length W3 of the exposed portions of the internal electrodes E1 and E2. In this case, the exposed portions of the internal electrodes E1, E2 are surely covered with the electrode portions 4a, 6a. Therefore, the multilayer capacitor C1 can be excellent in moisture resistance.

  In the multilayer capacitor C1, the length T1 from the third side surface 2c to the internal electrode E disposed closest to the third side surface 2c and the length W1 of the electrode portions 4b and 6b are as described above. Expression (1) is satisfied. By setting W1 / T1 to less than 8, an electrostrictive effect is generated in the portion sandwiched between the internal electrodes E1 and E2, and even if mechanical distortion occurs in the capacitor body 2, the electrode is applied to the distorted capacitor body 2. The portions 4d and 6d are less likely to be pulled. Further, by making W1 / T1 larger than 0.4, it is possible to prevent a contact failure from occurring when the electrode portions 4d and 6d are connected to the land electrodes of the substrate.

  In the multilayer capacitor C1, the pair of terminal electrodes 4 and 6 have electrode portions not only on the first and second side surfaces 2a and 2b but also on the third and fourth side surfaces 2c and 2d. Therefore, the connection between the terminal electrodes 4 and 6 and the land electrode of the substrate becomes easy.

  The preferred embodiments of the present invention have been described above. However, the present invention is not necessarily limited to the above-described embodiments, and various modifications can be made without departing from the scope of the present invention.

  For example, the number of stacked internal electrodes E1, E2 is not limited to the number in the above embodiment.

  In the present embodiment, the electrode portions 4d and 6d of the terminal electrodes 4 and 6 are connected to the land electrodes of the substrate, but the electrode portions 4e and 6e may be connected. The terminal electrodes 4 and 6 may not have the electrode portions 4d, 4e, 6d, and 6e. In this case, at least one of the electrode portions 4b and 4c and at least one of the electrode portions 6b and 6c are connected to the land electrode of the substrate.

  Further, although the terminal electrodes 4 and 6 are substantially cross-shaped on the first and second side surfaces 2a and 2b, they may be substantially T-shaped. More specifically, the electrode portions 4c, 4e, 6c, 6e or the electrode portions 4b, 4d, 6b, 6d may not be provided. Further, although the terminal electrodes 4 and 6 have the same shape, it is sufficient that at least one of the terminal electrodes 4 and 6 has the shape described in the above embodiment. However, from the viewpoint of reducing the contact area between the terminal electrode and the land electrode of the substrate and further reducing noise, it is desirable that both the terminal electrodes 4 and 6 have the shape shown in the above embodiment. .

It is the perspective view and side view of the multilayer capacitor which concern on this embodiment. It is sectional drawing of the multilayer capacitor which concerns on this embodiment. It is a graph which shows the relationship between W1 / T1 and the deformation amount of a board | substrate.

Explanation of symbols

E1, E2 ... internal electrodes, 4a-4e ... electrode portions, 6a-6e ... electrode portions, 2 ... capacitor body, 2a ... first side surface, 2b ... second side surface, 2c ... third side surface, 2d ... 4th side, 2e ... 5th side, 2f ... 6th side, 4, 6 ... terminal electrode, 7 ... exposed part, C1 ... multilayer capacitor.

Claims (3)

An element body made of a dielectric material;
A plurality of internal electrodes arranged in the element body so that at least some of them face each other;
A pair of terminal electrodes disposed on the element body,
Each of the plurality of internal electrodes has an exposed portion that is exposed to one of a pair of side surfaces that are parallel to a first direction in which the plurality of internal electrodes face each other and are opposed to each other, of the outer surface of the element body,
Each of the pair of terminal electrodes includes a first electrode portion and a second electrode portion continuous to the first electrode portion, and the first and second terminals included in one of the pair of terminal electrodes. The second electrode portion is disposed on one side surface of the pair of side surfaces, and the first and second electrode portions of the other terminal electrode of the pair of terminal electrodes are the other side surface of the pair of side surfaces. Placed in
The first electrode portion of the one terminal electrode covers the exposed portion exposed on the one side surface, and the second electrode portion of the one terminal electrode is the first side surface of the one side surface. Extending towards the edge intersecting the direction,
The first electrode portion of the other terminal electrode covers the exposed portion exposed on the other side surface, and the second electrode portion of the other terminal electrode is the first electrode portion on the other side surface. Extending towards the edge intersecting the direction,
In the second direction orthogonal to the first direction and the direction in which the pair of side surfaces oppose each other, the length of the second electrode portion of the one terminal electrode is exposed on the one side surface. Set to be smaller than the length of the part ,
The pair of terminal electrodes is disposed on a side surface orthogonal to the first direction of the outer surface of the element body, and is continuous with the second electrode portion and the second electrode in the second direction. Each further comprising a third electrode portion having the same length as the portion;
In each of the pair of terminal electrodes, the length W1 of the second and third electrode portions in the second direction and the side surface of the element body on which the third electrode portion is disposed are closest to the side surface. The length T1 in the first direction to the internal electrode arranged in the
0.4 <W1 / T1 <8
A multilayer capacitor characterized by satisfying the relational expression represented by:   In the second direction, the length of the second electrode portion of the other terminal electrode is set to be smaller than the length of the exposed portion exposed on the other side surface. The multilayer capacitor according to claim 1. In the second direction, the length of the first electrode portion of the one terminal electrode is set to be larger than the length of the exposed portion exposed on the one side surface, and the other 3. The length of the first electrode portion of the terminal electrode is set to be larger than the length of the exposed portion exposed on the other side surface. The multilayer capacitor described.

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