JPH11288840A - Ceramic electronic component - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic electronic component, which is formed without using conductive paste, has outer electrodes having superior mechanical strength and the thermal strength, and is low cost and has high dimensional accuracy. SOLUTION: Outer electrodes 4a and 4b comprising metal plates are bonded to terminal surfaces 2a and 2b of a ceramic element 1 so as to be conducted to parts (exposed parts) 3a and 3b, which are exposed to the surfaces (end surfaces) 2a and 2b of the ceramic element 1 of an inner electrode 3. Furthermore, the exposed parts 3a and 3b of the inner electrodes 3 are made to be protruded from the surfaces (end surfaces) 2a and 2b of the ceramic element 1. In addition, the outer electrodes 4a and 4b comprising the metal plates are conducted to the inner electrodes by welding or by the use of a conductive bonding agent.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic electronic component, and more particularly, to a ceramic electronic component having a structure in which an external electrode is provided on the surface of a ceramic element so as to conduct with an internal electrode provided in the ceramic. Related to electronic components.

[0002]

2. Description of the Related Art For example, a multilayer ceramic electronic component such as a multilayer ceramic capacitor is usually fired by laminating and pressing a laminate formed by laminating and pressing ceramic green sheets provided with internal electrode patterns. It is manufactured by arranging external electrodes so as to conduct with the exposed internal electrodes.

[0003] Incidentally, the internal electrode which is electrically connected to the external electrode shrinks and recedes during firing of the laminate, and sometimes does not conduct to the external electrode. Therefore, before disposing the external electrodes on the fired laminate, the internal electrodes are exposed on the surface of the laminate by a method such as barrel polishing.

However, when the barrel polishing is performed as described above, the internal electrodes are also shaved together with the ceramic constituting the element, so that the internal electrodes are flush with the ceramic surface or are slightly receded from the ceramic surface. Become.

Therefore, in order to further improve the connection reliability between the internal electrode and the external electrode, a method of alloying the internal electrode and the external electrode has conventionally been adopted. In this method, for example, a conductive paste containing Pd, Ag, or Ag-Pd as a conductive component is used as the internal electrode, and a conductive paste containing Ag or the like as the conductive component is used as the external electrode. An internal electrode and an external electrode are alloyed by applying a conductive paste to the element by dipping or the like, drying and sintering the element.

Then, if necessary, plating of nickel, tin, solder or the like is performed on the surface of the external electrode in order to improve the mountability (solderability).

[0007]

However, as described above, when an external electrode is formed using a conductive paste, the cost of the conductive paste is high, and the accuracy of the thickness of the applied conductive paste is ensured. However, there is a problem that the production cost is increased because expensive equipment is required, and a firing furnace is required to sinter the conductive paste.

[0008] In addition, pores usually occur in the external electrodes formed by sintering the conductive paste.
When plating is performed, a plating solution may permeate to cause deterioration of characteristics, and there is a problem that process control costs increase.

The present invention solves the above problems, and is a low cost, high dimensional accuracy ceramic having an external electrode formed without using a conductive paste and having excellent mechanical strength and thermal strength. The purpose is to provide electronic components.

[0010]

In order to achieve the above object, in a ceramic electronic component according to the present invention (claim 1), internal electrodes are provided in a ceramic in such a manner that a part thereof is exposed on the surface. A ceramic element having a structure described above, and an external electrode formed of a metal plate joined to the surface of the ceramic element so as to conduct to a portion of the internal electrode exposed on the surface of the ceramic element.

An external electrode made of a metal plate is joined to the surface of the ceramic element so as to be electrically connected to a portion of the internal electrode exposed on the surface of the ceramic element. And an external electrode having excellent thermal strength can be formed. In the present invention, preferred examples of the metal plate for the external electrode include silver, copper, nickel, iron, aluminum,
Examples include a metal plate made of tin, zinc, titanium, or the like, or an alloy plate containing these as a main component.

Further, the ceramic electronic component of claim 2 is
An exposed portion of the internal electrode protrudes from the surface of the ceramic element, and an external electrode made of the metal plate is provided so as to be electrically connected to the protruded portion.

When the exposed portion of the internal electrode is made to protrude from the surface of the ceramic element, and the external electrode made of a metal plate is provided so as to be electrically connected to the protruded exposed portion, the external electrode and the internal electrode can be more closely connected. The connection can be made surely, and the connection reliability can be further improved.

Further, the ceramic electronic component of claim 3 is:
The external electrode made of the metal plate is electrically connected to the internal electrode by welding or using a conductive adhesive.

When the external electrode made of a metal plate is electrically connected to the internal electrode by welding or using a conductive adhesive, the reliability of the connection of the external electrode to the ceramic element and the connection between the external electrode and the internal electrode are improved. The reliability can be further improved, and the present invention can be made more effective. Similar effects can be obtained by using an adhesive that does not contain a resin such as solder or solder.

Further, the ceramic electronic component of claim 4 is:
As the metal plate, a metal plate plated with a material having excellent solderability is used.

By using a metal plate plated with a material having excellent solderability as the metal plate, it is possible to improve the solderability of the external electrodes and to improve the mounting reliability. . In addition, as a material having excellent solderability, tin, solder and the like are exemplified.

[0018]

BEST MODE FOR CARRYING OUT THE INVENTION Hereinafter, embodiments of the present invention will be shown and features thereof will be described in more detail.

FIG. 1 is a cross-sectional view showing a ceramic electronic component (a multilayer ceramic capacitor in this embodiment) according to an embodiment of the present invention. In this multilayer ceramic capacitor, as shown in FIG. 1, a plurality of internal electrodes 3 are arranged so as to face each other via a ceramic layer 1a, and one end sides thereof are alternately provided with end faces 2a, 2a.
of the ceramic element 1 having a structure drawn out to the b side,
Exposed portions (ends) of the internal electrode 3 on the end surfaces 2a and 2b.
A metal plate (for example, a silver plate) so as to conduct with 3a and 3b
It is formed by joining external electrodes 4a and 4b made of.

The external electrodes 4a and 4b are plate-shaped and are joined to the end faces 2a and 2b of the ceramic element 1 by a conductive adhesive 5, and one external electrode 4a is connected to one end face 2a of the ceramic element 1. Exposed portion 3 of exposed internal electrode 3
a, and the other external electrode 4b is electrically connected to the exposed portion 3b of the internal electrode 3 exposed on the other end face 2b.

The external electrodes 4a and 4b may be made of various materials other than silver, such as metal plates made of copper, nickel, iron, aluminum, tin, zinc, titanium, or the like, or alloy plates containing these as main components. It is possible to use one.

In the first embodiment, the external electrodes 4
a, 4b are connected to the ceramic element 1 via the conductive adhesive 5.
Are joined to the end surfaces 2a and 2b, but it is also possible to join by a method such as high-frequency welding without using a conductive adhesive. In some cases, the external electrodes 4a and 4b may be directly pressed and joined (fitted) to the end surfaces 2a and 2b of the ceramic element 1 using a clip-shaped member.

As the external electrodes 4a and 4b, tin,
By using a metal plate plated with a material having excellent solderability such as solder, the mountability (solderability) of the product can be improved.

As described above, the multilayer ceramic capacitor of the first embodiment has the ceramic element 1
Since the external electrodes 4a and 4b made of a metal plate are joined to the end surfaces 2a and 2b of the ceramic element 1 so as to be electrically connected to the exposed portions 3a and 3b exposed on the end surfaces 2a and 2b, a conductive paste is used. Instead, an external electrode having excellent mechanical strength and thermal strength can be formed. As a result, it is possible to obtain a highly reliable and economical multilayer ceramic capacitor.

Further, since the external electrodes 4a and 4b are formed from a metal plate, not only can the external electrodes 4a and 4b be formed in a shape suitable for surface mounting, but also the external electrodes 4a and 4b can be connected to leads. A shape for a frame can be used, and the degree of freedom of the electrode shape can be greatly improved.

[Embodiment 2] FIG. 2 is a sectional view showing a multilayer ceramic capacitor according to another embodiment of the present invention, and FIG. 3 is a sectional view showing a state before an external electrode is provided. . As shown in FIG. 2, the multilayer ceramic capacitor according to the second embodiment is, like the multilayer ceramic capacitor according to the first embodiment, arranged such that a plurality of internal electrodes 3 are opposed to each other via a ceramic layer 1a. ,
The end faces 2a, 2b of the ceramic element 1 having a structure in which one end sides thereof are alternately drawn to the end faces 2a, 2b.
The external electrodes 4a and 4b made of a metal plate are joined so as to be electrically connected to the exposed portions (ends) 3a and 3b of the internal electrode 3. The external electrodes 4a, 4
As b, a material obtained by bending a silver plate material into a U-shape is used.

In the multilayer ceramic capacitor of the second embodiment, the end (exposed portion) of the internal electrode 3
2 and 3, projecting from the end surfaces 2a and 2b of the ceramic element 1 and the external electrodes 4a and 3b
A and 4b are joined to the end faces 2a and 2b of the ceramic element 1 via a conductive adhesive 5 (FIG. 2) in a state of contact with the ends 3a and 3b of the internal electrode 3. In this case, the external electrodes 4a and 4b do not necessarily have to contact the internal electrodes 3a and 3b.

The end portions 3a and 3b of the internal electrode 3 can be projected from the end surfaces 2a and 2b of the ceramic element 1 by, for example, a sand blast method or a chemical etching method.

That is, the ceramic on the end face of the ceramic element 1 is physically removed by the sandblasting method.
By exposing the end portions 3a and 3b of the internal electrode 3 or performing chemical etching using an appropriate etching solution corresponding to the ceramic constituting the ceramic element 1 to dissolve and remove the ceramic, the internal electrode 3 is removed. End 3a,
3b can be exposed.

In particular, the sand blast method is preferable because the exposed internal electrode 3 expands due to the malleability of the metal and the contact area with the external electrodes 4a and 4b increases.
In the multilayer ceramic capacitor according to the second embodiment, the external electrodes 4a and 4b may be made of copper, copper, or the like in addition to silver.
It is possible to use various plates such as a metal plate made of nickel, iron, aluminum, tin, zinc, titanium, or the like, or an alloy plate containing these as a main component.

As described above, the multilayer ceramic capacitor of the second embodiment has the end portions (exposed portions) 3 of the internal electrodes 3.
a, 3b are projected from the end surfaces 2a, 2b of the ceramic element 1, and the external electrodes 4a, 4b made of a metal plate are connected to the ends 3a, 3b of the internal electrodes 3 of the ceramic element 1 via the conductive adhesive 5. Since the bonding is made to the exposed end faces 2a, 2b, the ceramic elements 1 of the external electrodes 4a, 4b
Connection reliability, and external electrodes 4a, 4b and internal electrode 3
Can be further improved in connection reliability.

In the second embodiment, the external electrodes 4
a, 4b are connected to the ceramic element 1 via the conductive adhesive 5.
Are joined to the end surfaces 2a, 2b of the first and second electrodes, but it is also possible to join them by a method such as high-frequency welding. In some cases, the external electrodes 4a, 2b are formed using clip-shaped members.
4b is pressed directly against the end faces 2a and 2b of the ceramic element 1,
It is also possible to constitute so that it may join (fit).

In the second embodiment, the case where a metal plate which is bent in a U-shape is used as an external electrode is described. However, a metal plate which has been subjected to machining such as cutting or surface polishing is used. It is also possible.

Also in the multilayer ceramic capacitor of the second embodiment, since the metal plates plated with a material having excellent solderability, such as tin and solder, are used as the external electrodes 4a and 4b, Can be improved in mountability (solderability).

FIGS. 4 to 7 are sectional views showing modified examples of the multilayer ceramic capacitor of the present invention. In each of the figures, the same reference numerals as those in FIGS. Is shown.

That is, in the multilayer ceramic capacitor of FIG. 4, the lower portions of the external electrodes 4a and 4b are bent inward, and serve as mounting portions when the multilayer ceramic capacitor is mounted (mounted) on the substrate 12 by the solder 20. Therefore, the mounting area can be reduced.

In the monolithic ceramic capacitor shown in FIG. 5, the lower portions of the external electrodes 4a and 4b are bent outward. Mounting part.

The multilayer ceramic capacitor shown in FIG. 6 is a so-called stack type multilayer ceramic capacitor in which two ceramic elements 1 are stacked, and the lower portions of the external electrodes 4a and 4b are bent outward. The bent portion is a mounting portion when the multilayer ceramic capacitor is mounted on the substrate 12 with the screw 11.

Further, the multilayer ceramic capacitor of FIG. 7 is a multilayer ceramic capacitor in which a plurality of ceramic elements 1 are arranged side by side to form a block, and the external electrodes 4a, 4b
Are connected to the side surfaces 21a of the ceramic element block 21 via the conductive adhesive 5 so as to be electrically connected to the ends 3a and 3b of the internal electrodes 3 protruding from the end faces 2a and 2b of each ceramic element 1. Note that the end face 21 b side of the ceramic element block 21 is sealed with a sealing resin 22.

In the first and second embodiments, the surface mount type multilayer ceramic capacitor has been described as an example. However, since the external electrodes are formed of a metal plate, the degree of freedom in the shape of the external electrodes is greatly improved. For example, in the case of a ceramic electronic component having a lead frame, which is not a surface mount type, the external electrode can be formed into a shape that also functions as a lead frame.

In the above embodiment, a multilayer ceramic capacitor has been described as an example. However, the present invention is not limited to a multilayer ceramic capacitor, but may be applied to the surface of a ceramic element having internal electrodes so as to be electrically connected to the internal electrodes. The present invention can be applied to various ceramic electronic components provided with electrodes.

In addition, the present invention is not limited to the above embodiment in other respects, but relates to the pattern and the constituent material of the internal electrode, the arrangement position of the external electrode, the type of the conductive adhesive, and the like. Various applications and modifications can be made within the scope of the invention.

[0043]

As described above, in the ceramic electronic component of the present invention, a metal plate is bonded to the surface of the ceramic element to form an external electrode so as to conduct with the portion of the internal electrode exposed on the surface of the ceramic element. , Apply conductive paste,
It is possible to form an external electrode having excellent mechanical strength and thermal strength without baking, and it is not necessary to apply and paste a conductive paste. Will be possible. In addition, since the metal plate, which is a machined product, is used as the external electrode, the dimensional accuracy can be greatly improved compared to the case where the external electrode is formed by a method such as dipping. Since it can be formed in a shape corresponding to the mounting method, it is possible to provide a low-cost ceramic electronic component suitable for the application.

Also, as in the ceramic electronic component of the second aspect, the exposed portion of the internal electrode is projected from the surface of the ceramic element, and the external electrode made of a metal plate is provided so as to be electrically connected to the projected exposed portion. In this case, the connection reliability between the external electrode and the internal electrode can be further improved.

Further, when the external electrode made of a metal plate is electrically connected to the exposed internal electrode by welding or by using a conductive adhesive as in the third aspect of the present invention, the external electrode is connected to the internal electrode. The connection reliability of the electrodes can be further improved.

Further, the use of a metal plate plated with a material having excellent solderability as in the ceramic electronic component of claim 4 improves the solderability of the external electrodes. Thus, the mounting reliability can be further improved. Further, unlike the conventional case, it is not necessary to perform plating on the external electrode after forming the external electrode on the ceramic element in order to improve the solderability, and it is not necessary to immerse the ceramic element in a plating solution. Therefore, deterioration of characteristics can be prevented.

[Brief description of the drawings]

FIG. 1 is a cross-sectional view illustrating 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 according to another embodiment (Embodiment 2) of the present invention.

FIG. 3 is a view showing a state before mounting external electrodes of the ceramic electronic component of the second embodiment.

FIG. 4 is a view showing a modification of the ceramic electronic component according to the embodiment of the present invention.

FIG. 5 is a view showing another modification of the ceramic electronic component according to the embodiment of the present invention.

FIG. 6 is a view showing still another modification of the ceramic electronic component according to the embodiment of the present invention.

FIG. 7 is a view showing still another modification of the ceramic electronic component according to the embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Ceramic element 1a Ceramic layer 2a, 2b End surface 3 Internal electrode 3a, 3b Exposed part (end) of internal electrode 4a, 4b External electrode 5 Conductive adhesive 11 Screw 12 Substrate 20 Solder 21 Ceramic element block 21a Ceramic element block 21a Side surface 21b End surface of ceramic element block 22 Sealing resin

 ──────────────────────────────────────────────────の Continuing on the front page (72) Inventor Takeshi Azumi 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Stock Company Murata Manufacturing Co., Ltd. Inside Murata Manufacturing Co., Ltd. (72) Inventor Makoto Murata 2-26-10 Tenjin, Nagaokakyo-shi, Kyoto Co., Ltd.Inside Murata Manufacturing Co., Ltd.

Claims (4)

[Claims] A ceramic element having a structure in which an internal electrode is disposed in a ceramic such that a part thereof is exposed on the surface, and a ceramic element which is electrically connected to a part of the internal electrode exposed on the surface of the ceramic element. A ceramic electronic component, comprising: an external electrode formed of a metal plate joined to a surface of the element. 2. An exposed portion of the internal electrode protrudes from the surface of the ceramic element, and an external electrode made of the metal plate is provided so as to be electrically connected to the protruded portion. The ceramic electronic component according to claim 1. 3. The ceramic electronic component according to claim 1, wherein the external electrode made of the metal plate is electrically connected to the internal electrode by welding or using a conductive adhesive. 4. A ceramic electronic component according to claim 1, wherein said metal plate is a metal plate plated with a material having excellent solderability. .