JP3780399B2 - Ceramic electronic components - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a ceramic electronic component, and more particularly to a ceramic electronic component with an external terminal in which an external terminal is attached to an electronic component element in which an internal electrode is disposed in ceramic so as to be electrically connected to the internal electrode.
[0002]
[Prior art]
Some ceramic electronic components are provided with external terminals for board mounting. As such a ceramic electronic component with an external terminal, for example, as shown in FIGS. 13 (a) and 13 (b), it is electrically connected to the internal electrode 52 disposed in the ceramic 51 (FIG. 13 (b)). In this manner, horizontal connection portions 71 are formed by bending portions (lower end portions) to be bonded to a printed circuit board (not shown) or the like at right angles on both end faces of the chip-type ceramic electronic component element 54 on which the external electrodes 53 are formed. There is a ceramic electronic component in which the metal external terminal 55 is joined via a joining material 56 such as solder, conductive adhesive, or conductive paste.
[0003]
Further, as shown in FIG. 14, a ceramic electronic component element formed by stacking a plurality of chip-type ceramic electronic component elements 54 in which external electrodes 53 are formed so as to be electrically connected to internal electrodes 52 disposed in ceramic 51. A metal external terminal 55 in which a horizontal connection portion 71 is formed by bending a portion (lower end portion) to be joined to a printed circuit board (not shown) or the like to the (stack element) 64 to form a horizontal connection portion 71 is soldered or conductively bonded. There is a ceramic electronic component joined through a joining material 56 such as an agent or a conductive paste.
[0004]
By the way, in such a ceramic electronic component, as the external terminals 55 attached to both end faces of the ceramic electronic component element 54 or a ceramic electronic component (stacked element) 64 (electronic component element) in which a plurality of them are usually stacked, An external terminal 55 is used in which the thickness T1 of the joint portion 70 joined to both end faces of the component element 54 (64) is the same as the thickness T2 of the horizontal connection portion 71 joined to a printed circuit board or the like.
[0005]
[Problems to be solved by the invention]
However, as described above, when a heat shock in a product heat cycle test or the like is applied to the ceramic electronic component formed by joining the external terminal 55 to the electronic component element 54 (64), the electronic component element 54 (64) is configured. Stress that cannot be ignored is generated due to the difference in the coefficient of linear expansion between the ceramic 51 and the external terminal 55, and the stress is considerably large at both ends of the external terminal 55. Therefore, in some cases, as shown in FIG. 15, there is a problem that a crack C is generated at a corner portion of the electronic component element 54 (64), and there is a problem that reliability is not necessarily sufficient.
[0006]
The present invention solves the above problems, and provides a highly reliable ceramic electronic component with external terminals that can prevent cracks from occurring in the ceramic electronic component element due to thermal shock. The purpose is to do.
[0007]
[Means for Solving the Problems]
In order to achieve the above object, a ceramic electronic component of the present invention (Claim 1) includes:
A ceramic electronic component element having a structure in which an internal electrode is disposed in a ceramic in such a manner that a part of the ceramic electronic component element is exposed on the end face, or a stacked element (electronic component element) formed by stacking a plurality of the ceramic electronic component elements;
A ceramic electronic component comprising: an external terminal made of a metal plate joined to the end face of the electronic component element so as to be electrically connected to the internal electrode exposed on the end face of the electronic component element;
The thickness of at least the joint portion (joint portion to the end face of the electronic component element) of the external terminal is made thinner than the thickness of other portions so that the stress applied to the electronic component element can be reduced by the heat-cooling heat cycle . It is characterized by this.
[0008]
External terminal, a thickness of at least the joint, the heat cycle of heating and cooling enough to reduce the stress applied to the electronic element, by also thin thickness relatives of other parts, during cooling in the heat cycle of heating and cooling The stress on the electronic component element (ceramic electronic component element or a stacked element obtained by stacking them) resulting from the contraction of the external terminal is reduced. Therefore, it is possible to reduce the generation of stress due to the heat cycle, prevent the occurrence of cracks in the electronic component element, and improve the reliability.
[0009]
In order to make the thickness of the joint part thinner than the other part, for example, a step is provided between the joint part and the other part, and the joint part has a uniform thickness smaller than the other part. It is possible to adopt a configuration such as forming a region, or forming a portion including the joint portion of the external terminal so that the thickness becomes thinner toward the tip, and the thickness is made smaller than other portions.
[0010]
The present invention is also applicable to a case storage type ceramic electronic component in which an electronic component element is stored in a case, and a resin injection type ceramic electronic component in which an electronic component element is stored in a case and potted with an injection resin. Is possible.
[0011]
Further, in the ceramic electronic component according to claim 2, the external terminal is made of at least one selected from the group consisting of Cu, Ni, Fe, Ag, and alloys thereof, and alloys composed mainly of these. It is characterized by being.
[0012]
As the external terminals, Cu, Ni, Fe, Ag, and alloys thereof, and further, at least one selected from the group consisting of alloys containing these as main components are used to ensure the necessary mechanical strength. However, it is possible to reduce the stress applied to the electronic component element by making the thickness of the joint portion smaller than that of the other portions, and to secure the current capacity.
[0013]
In the ceramic electronic component of claim 3, the external terminal is bonded to an external electrode formed on an end surface of the electronic component element through a conductive bonding material so as to be electrically connected to the internal electrode. And the junction part of an external terminal has the thickness which can ensure the current capacity required for a ceramic electronic component, combining with the said external electrode and joining material.
[0014]
The current capacity can be secured by setting the thickness of the joint portion of the external terminal to a value that can secure the current capacity necessary for the ceramic electronic component in consideration of the thickness of the external electrode and the joining material. It is possible to reduce the stress applied to the electronic component element by reducing the thickness of the joint as much as possible, and the present invention can be more effectively realized.
[0015]
In the case of a ceramic electronic component in which the external electrode is made of a thick film electrode, the current capacity can be secured by the external electrode in many cases, but the ceramic electronic having the external electrode made of a thin film electrode formed by sputtering or the like. In the case of a component, it may be difficult to ensure a sufficient current capacity with only external electrodes. However, as described in claim 3, by setting the thickness of the joint portion of the external terminal in consideration of the current capacity, the current capacity can be surely secured, and a highly reliable ceramic electronic component can be obtained. Obtainable.
[0016]
The ceramic electronic component of claim 4 is characterized in that the external terminal includes a reinforcing structure for reinforcing the joint portion.
By providing the external terminal with a reinforcement structure for reinforcing the joint, the strength of the external terminal, which has been reduced by reducing the thickness of the joint, is compensated, and a highly reliable ceramic electronic component is provided. Will be able to.
[0017]
As the reinforcing structure, various structures such as a structure in which a part of the external terminal is bent or a structure in which a reinforcing member is attached can be employed.
[0018]
DETAILED DESCRIPTION OF THE INVENTION
Hereinafter, embodiments of the present invention will be shown and the features thereof will be described in more detail.
[0019]
[Embodiment 1]
FIG. 1 is a perspective view showing a ceramic electronic component (a stack type multilayer ceramic capacitor in this embodiment) according to an embodiment of the present invention, and FIG. 2 is a ceramic electronic component element constituting the ceramic electronic component of FIG. FIG.
[0020]
This ceramic electronic component (multilayer ceramic capacitor) is soldered to both end surfaces of a stacked element (electronic component element) 14 in which a plurality of ceramic electronic component elements 4 having a pair of external electrodes 3 and 3 disposed on both end surfaces are stacked. The pair of external terminals 5 and 5 are joined to each other through a joining material 6 such as a conductive adhesive or a conductive paste.
As shown in FIG. 2, the ceramic electronic component element 4 is arranged such that a plurality of internal electrodes 2 are opposed to each other through a ceramic (ceramic layer) 1 and one end side thereof is alternately different. It has a structure in which a pair of external electrodes 3 and 3 are disposed on both end surfaces so as to be electrically connected to the exposed internal electrode 2 while being drawn out to the end surface.
[0021]
The external terminal 5 is formed by bending a metal plate (for example, a silver plate) into an L shape, and includes a vertical portion 5a and a horizontal portion 5b. A part of the vertical part 5a becomes a joint part 10 joined to the electronic component element 14, and the horizontal part 5b becomes a connection part 11 to a printed circuit board (not shown) or the like.
[0022]
In this embodiment, the step portion 7 is formed on the surface of the vertical portion 5a facing the electronic component element 14, and the thickness T1 of the joint portion 10 is the connection portion 11 to the printed circuit board or the like of the horizontal portion 5b. The other part is formed thinner than the thickness T2.
[0023]
In this embodiment, the external electrode 3 is a thin film electrode formed by a thin film forming method such as a sputtering method, and since the thickness thereof is thin, the external electrode 3 and the bonding material 6 are combined with the ceramic electronic component. The thickness T1 of the joint 10 is set so that the necessary current capacity can be ensured. In the present invention, as the external electrode 3, a thick film electrode formed by applying and baking a conductive paste can also be used.
[0024]
In the ceramic electronic component of the first embodiment, since the thickness T1 of the joint portion 10 of the external terminal 5 is made thinner than the thickness T2 of other portions, the external terminal 5 contracts during cooling of the heat cycle of heating and cooling. It is possible to reduce the stress on the electronic component element 14 resulting from the operation. Therefore, it is possible to suppress and prevent the occurrence of cracks in the electronic component element 14 due to the stress caused by the heat cycle, and to improve the reliability.
[0025]
Further, since the thickness T1 of the joint portion 10 is set so as to ensure a necessary current capacity, even when the external electrode 3 is a thin film electrode, the external electrode 3, the bonding material 6 and the external terminal As a result, the necessary current capacity can be ensured by the entire connecting portion 10, and a highly reliable ceramic electronic component can be obtained.
[0026]
In the above embodiment, the case where the horizontal portion 5b of the external terminal 5 is bent outward has been described. However, as shown in FIG. 3, the horizontal portion 5b may be bent inward. In that case, the planar area of the product is reduced, and the packaging density can be increased.
[0027]
Moreover, although the said embodiment demonstrated the case where the level | step-difference part 7 of the external terminal 5 was formed in the opposing surface with the electronic component element 14, as shown in FIG. Can have a structure in which a stepped portion 7 is formed on the opposite surface (outer surface).
[0028]
In forming the external terminal 5 having the stepped portion 7, for example, as shown in FIG. 5 (a), the flat metal plate 17 is bent or as shown in FIG. 5 (b). By joining the two members (metal plates) 16a and 16b, the external terminal 5 having the stepped portion 7 as shown in FIG. 5C can be easily formed.
[0029]
[Embodiment 2]
FIG. 6 is a perspective view showing a main part of a ceramic electronic component according to another embodiment of the present invention.
In the ceramic electronic component of this embodiment, the entire thickness T1 of the vertical portion 5a of the external terminal 5 is configured to be thinner than the thickness T2 of the horizontal portion 5b that becomes the connection portion 11 to a printed circuit board or the like. .
Since other configurations are the same as those in the first embodiment, description thereof is omitted.
[0030]
In the ceramic electronic component of this embodiment, the entire thickness T1 of the vertical portion 5a of the external terminal 5 is thinner than the thickness T2 of the horizontal portion 5b that becomes the connection portion 11 to the printed board or the like, and the joint portion 10 is also horizontal. Since it is included in the vertical portion 5a having a thickness T1 smaller than the thickness T2 of the portion 5b, it is possible to reduce the stress applied to the electronic component element 14 (ceramic electronic component element 4) from the external terminal 5. Therefore, as in the case of the first embodiment, it is possible to reduce the generation of stress due to the heat cycle, prevent the electronic component element 14 from being cracked, and improve the reliability.
[0031]
Note that the external terminal 5 in which the thickness T1 of the vertical portion 5a is thinner than the thickness T2 of the horizontal portion 5b is, for example, as shown in FIG. 7A, a metal plate 16a to be the thin vertical portion 5a, A metal plate 16b to be a large horizontal portion 5b is prepared as a separate member, and this should be joined together or as shown in FIG. 7B, to become the horizontal portion 5b of the metal plate 16a bent at a right angle. By joining another metal plate 16b to the part or bending the metal plate 17 so that only the horizontal portion 5b is doubled as shown in FIGS. 7 (c) and (d), As shown in FIG. 7E, the external terminal 5 in which the thickness T1 of the vertical portion 5a is thinner than the thickness T2 of the horizontal portion 5b can be easily formed.
[0032]
[Embodiment 3]
FIG. 8 is a perspective view showing a ceramic electronic component according to another embodiment of the present invention.
In the ceramic electronic component of this embodiment, the external terminal 5 is formed such that the thickness of the vertical portion 5a becomes thinner toward the tip side (upper side), and the thickness T1 of the joint portion 10 to the electronic component element 14 is increased. Also, it is formed so as to become thinner toward the upper side and to be thinner than the thickness T2 of the horizontal portion 5b that becomes the connection portion 11 to the printed circuit board or the like.
Since other configurations are the same as those in the first embodiment, description thereof is omitted.
[0033]
In the ceramic electronic component of this embodiment, the thickness T1 of the vertical portion 5a of the external terminal 5 is formed so as to decrease toward the tip side (upper side), and the thickness T1 of the connection portion 10 is connected to a printed circuit board or the like. Since it is formed so as to be thinner than the thickness T2 of the horizontal portion 5b to be the portion 11, the same effect as in the first and second embodiments can be obtained, and the thickness T1 of the vertical portion 5a of the external terminal 5 can be obtained. However, since it is formed so as to become thinner toward the tip side (upper side), it is possible to reduce the stress applied from the external terminal 5 to the upper ceramic electronic component element 4 that is easily affected by the surrounding temperature change. It becomes possible. Accordingly, it is possible to further reduce the occurrence of stress due to the heat cycle and more reliably prevent the occurrence of cracks in the electronic component element 14 (ceramic electronic component element 4).
[0034]
[Embodiment 4]
9, 10, 11, and 12 are all perspective views showing ceramic electronic components according to other embodiments of the present invention. In these ceramic electronic components, the external terminal 5 has a thickness T1 of the joint 10. Is provided with a reinforcing structure for compensating for a decrease in mechanical strength due to the thickness of the horizontal portion 5b being thinner than the thickness T2 of the horizontal portion 5b (connection portion 11 to the printed circuit board or the like).
[0035]
That is, the ceramic electronic component of FIG. 9 includes a reinforcing structure in which triangular reinforcing members 21 are joined and fixed to the vertical portion 5a and the horizontal portion 5b of the external terminal 5 bent outward. The ceramic electronic component includes a reinforcing structure in which a substantially L-shaped reinforcing member 21 is joined and fixed to the vertical portion 5a and the horizontal portion 5b of the external terminal 5 bent outward.
[0036]
Further, the ceramic electronic component of FIG. 11 has a reinforcing structure in which a strip-shaped reinforcing member 21 is joined and fixed to the vertical portion 5a of the external terminal 5 in which the horizontal portion 5b is bent inward.
[0037]
Further, the ceramic electronic component of FIG. 12 includes a reinforcing structure portion 22 formed by bending the vertical portion 5a of the external terminal 5.
[0038]
As described above, the ceramic electronic components of FIGS. 9 to 12 have sufficient mechanical strength even though the joint portion 10 is thinned because the external terminal has a reinforcing structure. A highly reliable ceramic electronic component can be obtained.
[0039]
In each of the above embodiments, a stack type ceramic electronic component in which a plurality of ceramic electronic component elements are stacked has been described as an example. However, in the present invention, external terminals are joined to both end faces of a single ceramic electronic component element. Needless to say, the present invention can also be applied to fixed ceramic electronic components.
[0040]
In the above embodiment, an example in which the electronic component element is stored in the case is not particularly shown. However, the present invention is not limited to the case storage type ceramic electronic component in which the electronic component element is stored in the case, or the electronic component element. Can be applied to resin-injection-type ceramic electronic components that are housed in a case and potted with an injection resin.
[0041]
In the above embodiment, the multilayer ceramic capacitor has been described as an example. However, the present invention is not limited to the multilayer ceramic capacitor, and the external terminal is connected to the surface of the ceramic electronic component element including the internal electrode so as to be electrically connected to the internal electrode. It is possible to apply to various ceramic electronic parts formed by arranging
[0042]
In addition, the present invention is not limited to the above embodiment in other respects, and relates to the type of ceramic constituting the ceramic electronic component element, the pattern and constituent material of the internal electrode, the arrangement position of the external terminal, and the like. Various applications and modifications can be made within the scope of the invention.
[0043]
【The invention's effect】
As described above, the ceramic electronic component of the present invention has a thickness of at least the joint portion of the external terminal that is thinner than the thickness of other portions to such an extent that the stress applied to the electronic component element by the heat cycle of heating and cooling can be reduced. Therefore, it is possible to reduce the stress on the electronic component element made of ceramic, which is caused by the contraction of the external terminal during the cooling of the heat cycle of heating and cooling, and to prevent the occurrence of cracks in the electronic component element Thus, reliability can be improved.
[0044]
Further, as in the ceramic electronic component of claim 2, the external terminal is made of at least one selected from the group consisting of Cu, Ni, Fe, Ag, and alloys thereof, and alloys composed mainly of these. When using a material, the required mechanical strength is ensured, the thickness of the joint is made smaller than other parts, the stress applied to the electronic component element is reduced, and the required mechanical strength is ensured. And a current capacity can be secured.
[0045]
Further, as in the ceramic electronic component according to claim 3, the thickness of the joint portion of the external terminal is set to a value that can secure a current capacity necessary for the ceramic electronic component in consideration of the thickness of the external electrode and the bonding material. Therefore, it is possible to reduce the stress applied to the electronic component element by reducing the thickness of the joint as long as the current capacity can be secured, and the present invention can be more effectively realized. Can do.
[0046]
In addition, as in the ceramic electronic component of claim 4, the external terminal has a reinforcing structure for reinforcing the joint, thereby reducing the strength of the external terminal which is reduced by reducing the thickness of the joint. In addition, a highly reliable ceramic electronic component can be provided.
[Brief description of the drawings]
FIG. 1 is a perspective view showing a ceramic electronic component according to an embodiment (Embodiment 1) of the present invention.
FIG. 2 is a cross-sectional view showing a ceramic electronic component element constituting the ceramic electronic component according to one embodiment (first embodiment) of the present invention.
FIG. 3 is a perspective view showing a modified example of the ceramic electronic component according to the first embodiment of the present invention.
FIG. 4 is a perspective view showing another modified example of the ceramic electronic component according to the first embodiment of the present invention.
FIGS. 5A, 5B, and 5C are views for explaining a method of manufacturing an external terminal of a ceramic electronic component according to the first embodiment of the present invention.
FIG. 6 is a perspective view showing a main part of a ceramic electronic component according to another embodiment (Embodiment 2) of the present invention.
7A, 7B, 7C, 7D, and 7E are views for explaining a method of manufacturing an external terminal of a ceramic electronic component according to a second embodiment of the present invention.
FIG. 8 is a perspective view showing a ceramic electronic component according to still another embodiment (Embodiment 3) of the present invention.
FIG. 9 is a perspective view showing a ceramic electronic component according to yet another embodiment (Embodiment 4) of the present invention.
FIG. 10 is a perspective view showing a ceramic electronic component according to still another embodiment (Embodiment 4) of the present invention.
FIG. 11 is a perspective view showing a ceramic electronic component according to still another embodiment (Embodiment 4) of the present invention.
FIG. 12 is a perspective view showing a ceramic electronic component according to still another embodiment (Embodiment 4) of the present invention.
13A and 13B are diagrams showing a conventional ceramic electronic component, in which FIG. 13A is a plan view and FIG. 13B is a front sectional view.
FIG. 14 is a front sectional view showing another conventional ceramic electronic component.
FIG. 15 is a plan view showing a state in which a crack has occurred in a ceramic electronic component element of a conventional ceramic electronic component.
[Explanation of symbols]
1 Ceramic (ceramic layer)
2 Internal electrode 3 External electrode 4 Ceramic electronic component element 5 External terminal 5a Vertical portion of external terminal 5b Horizontal portion of external terminal 6 Bonding material 7 Stepped portion 10 Junction portion to electronic component element 11 Connection portion to printed circuit board 14 Stacking Element (electronic component element)
T1 Joint thickness T2 Thickness of other parts of external terminal 16a, 16b, 17 Metal plate 21 Reinforcement member 22 Reinforcement structure

Claims (4)

A ceramic electronic component element having a structure in which an internal electrode is disposed in a ceramic in such a manner that a part of the ceramic electronic component element is exposed on the end face, or a stacked element formed by stacking a plurality of ceramic electronic component elements (hereinafter simply referred to as “electronic component element”) ")
A ceramic electronic component comprising: an external terminal made of a metal plate joined to the end face of the electronic component element so as to be electrically connected to the internal electrode exposed on the end face of the electronic component element;
The thickness of at least the joint portion (joint portion to the end face of the electronic component element) of the external terminal is made thinner than the thickness of other portions so that the stress applied to the electronic component element can be reduced by the heat-cooling heat cycle . Ceramic electronic parts characterized by this.   2. The external terminal is made of at least one selected from the group consisting of Cu, Ni, Fe, Ag, and alloys thereof, and alloys composed mainly of these. Ceramic electronic components.   The external terminal is bonded to an external electrode formed on an end surface of the electronic component element so as to be electrically connected to the internal electrode through a conductive bonding material, and a bonding portion of the external terminal is 3. The ceramic electronic component according to claim 1, wherein the ceramic electronic component has a thickness capable of securing a current capacity required for the ceramic electronic component together with the external electrode and the bonding material.   The ceramic electronic component according to claim 1, wherein the external terminal includes a reinforcing structure for reinforcing the joint portion.

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