JPH11214243A - Ceramic electronic component and their manufacture - Google Patents

Abstract

PROBLEM TO BE SOLVED: To prevent ceramic electronic components from being damaged mechanically by the shrinkage of solder when the component are soldered to a wiring board or the expansion and shrinkage of the wiring board after the components are mounted on the board without attaching any terminal member composed of a metallic sheet. SOLUTION: Ceramic electronic components are constructed in a two-layer structure containing at least an inner layer 6 and an outer layer 7 which is partially bonded to the inner layer 6 through a conductive connecting section 8. Consequently, the outer layer 7 prevents the influences of stresses caused by the shrinkage of solder or the expansion and shrinkage of a wiring board on the main body 3 of the electronic components by favorably absorbing the stresses, because the layer 7 is easily deformable.

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 a method of manufacturing the same, and more particularly, to an improvement in the structure of a terminal electrode of a ceramic electronic component having a chip-shaped electronic component body made of ceramic and the like. The present invention relates to a method for manufacturing a ceramic electronic component having various terminal electrodes.

[0002]

2. Description of the Related Art Ceramic electronic components having a chip-shaped electronic component body made of ceramic, which are of interest to the present invention, include, for example, capacitors, resistors, inductors, filters, and the like. In many cases, it is surface-mounted on an appropriate wiring board.

In the above-described ceramic electronic component to be surface-mounted, terminal electrodes are formed on at least each end face of the electronic component main body. Is soldered to a predetermined conductive land. At this time, due to the stress generated due to the shrinkage effect due to the solidification of the solder, the ceramic electronic component is subjected to stress attracted to each terminal electrode side. As a result, mechanical damage such as cracking of the electronic component body may be caused to the ceramic electronic component.

[0004] Such mechanical damage to ceramic electronic components is also likely to occur in the following situations. That is, this is a case where the ceramic electronic component is mounted on a wiring board made of, for example, aluminum having excellent heat dissipation. In this case, since the difference in thermal expansion between the aluminum substrate and the ceramic electronic component is relatively large, as a result of a temperature cycle in which the temperature rises and falls repeatedly, for example, cracks occur in the electronic component body or cracks occur in the solder fillet. May occur.

[0005] Mechanical damage in the electronic component body is particularly likely to occur when a high-capacity Pb-based multilayer ceramic capacitor is mounted on a wiring board, for example, because its bending strength is relatively low. In order to solve the above-mentioned problems, a ceramic electronic component in which a terminal member made of a metal plate is attached to a terminal electrode by soldering has been put to practical use. According to the ceramic electronic component having such a structure, much of the stress that can be caused by the shrinkage of the solder for mounting or the expansion and contraction of the wiring board is absorbed by the deformation of the terminal member, and is directly applied to the electronic component body. Can not be.

[0006]

However, the ceramic electronic component having the above-mentioned terminal member has the following problems. First, as the terminal members, those having various dimensions must be prepared according to the dimensions of the ceramic electronic component, and various molds are required to obtain such terminal members having various dimensions. As a result, the cost of the ceramic electronic component increases.

Further, the work of soldering the terminal members to the terminal electrodes is relatively complicated. Further, at the time of this soldering, a thermal shock is applied to the electronic component body, and a crack may be formed. In addition, since the terminal member usually limits the direction in which the ceramic electronic component is mounted on the wiring board to one specific direction, the degree of freedom in the mounting direction of the ceramic electronic component is impaired.

Further, depending on the type of metal constituting the terminal member, an undesirable increase in equivalent series resistance may occur. Further, as described above, the terminal member has an action of absorbing the stress generated at the time of solidification of the solder due to its deformation. However, since this deformation of the terminal member usually occurs within the elastic limit, It is inevitable that stress remains in the terminal members. In addition, cracks may occur between the terminal electrode and the terminal member during the temperature cycle.

An object of the present invention is to provide a ceramic electronic component and a method of manufacturing the same, which can solve the various problems described above.

[0010]

A ceramic electronic component according to the present invention is a ceramic electronic component comprising: a chip-shaped electronic component main body; and terminal electrodes formed on at least each end face of the electronic component main body. In order to solve the above-mentioned technical problems, each terminal electrode has at least a two-layer structure having an inner layer and an outer layer partially joined to each other via a conductive connection portion. It is characterized by doing.

In the ceramic electronic component according to the present invention, preferably, the terminal electrode has an adjacent surface extension extending to an adjacent surface adjacent to the end surface of the electronic component main body, and at the adjacent surface extension, an end of the outer layer is provided. The distance between the edge and the end face of the electronic component body is set longer than the distance between the edge of the inner layer and the end face of the electronic component body. In the ceramic electronic component according to the present invention, it is preferable that the outer layer is formed of a conductive thick film obtained by firing a conductive paste.

[0012] In the ceramic electronic component according to the present invention, the joining portion that partially connects the inner layer and the outer layer may include:
It is preferable that each of the end faces of the electronic component body is positioned at the center in the surface direction. In the ceramic electronic component according to the present invention, a gap is formed between the inner layer and the outer layer, and inclusions such as a large number of particles are formed in a state where the gap between the inner layer and the outer layer is allowed to change. May exist.

The present invention is also applied to a ceramic electronic component having a plurality of electronic component bodies. in this case,
The plurality of electronic component bodies are stacked with their respective end faces aligned in the plane direction.Preferably, the connecting portion is formed so as to join the respective inner layers of the plurality of electronic component bodies to each other, and forms the outer layer. Are formed so as to cover each end face of the plurality of electronic component bodies in common.

[0014] The present invention is also directed to a method of manufacturing a ceramic electronic component as described above. This method of manufacturing a ceramic electronic component includes a step of preparing an electronic component main body, a step of forming an inner layer on at least each end face of the electronic component main body, and excluding a region where a connection portion is to be formed, so as to cover at least the inner layer. Forming a burnt film containing a substance that is burned off by firing; forming an outer layer film made of a conductive paste to be an outer layer by firing so as to cover the burnt film; and firing the burned film and the outer layer film. And a process.

The above-mentioned fired film may contain particles of a substance remaining after firing in addition to a substance which is burned off by firing, and in this case, particles of the same quality as the latter particles of the remaining substance may be contained. , Is preferably also contained in the outer layer film. Further, the method for manufacturing a ceramic electronic component according to the present invention may further include a step of partially providing a conductor on the inner layer in order to form the connection portion.

[0016]

FIG. 1 is a sectional view schematically showing a ceramic electronic component 1 according to one embodiment of the present invention. Referring to FIG. 1, ceramic electronic component 1 constitutes a multilayer ceramic capacitor. The ceramic electronic component 1 includes a chip-shaped electronic component main body 3 having a plurality of stacked dielectric ceramic layers 2, and terminal electrodes 4 are respectively formed on at least end faces of the electronic component main body 3. The detailed structure of the terminal electrode 4 will be described later.

Inside the electronic component main body 3, a plurality of internal electrodes 5 are formed in a laminated shape. These internal electrodes 5
Those electrically connected to one terminal electrode 4 and those electrically connected to the other terminal electrode 4 are alternately arranged. The terminal electrode 4 has at least a two-layer structure including an inner layer 6 and an outer layer 7. The inner layer 6 and the outer layer 7 are partially joined to each other via a conductive connection portion 8. In other words, the inner layer 6 and the outer layer 7 are
In portions other than the portion where is present, they may be in contact with each other, but not joined to each other. The connection unit 8
In this embodiment, each of the end faces of the electronic component body 3 is located at the center in the surface direction.

FIG. 2 shows a portion II of FIG. 1 in an enlarged manner. In this embodiment, the connection portion 8 has a predetermined thickness, so that a gap 9 is formed between the inner layer 6 and the outer layer 7, as is well shown in FIG. This gap 9 has a size of, for example, about 20 to 50 μm. The terminal electrode 4 has an adjacent surface extension 10 that extends to an adjacent surface adjacent to the end surface of the electronic component body 3. In this adjacent surface extension 10, as shown in FIG. 1, the distance a between the edge of the outer layer 7 and the edge of the electronic component body 3 is preferably the edge of the inner layer 6 and the edge of the electronic component body 3. Is longer than b. In other words, the edge of the inner layer 6 is covered by the outer layer 7.

As described above, according to the ceramic electronic component 1 according to the present embodiment, when the terminal electrode 4 is soldered to the conductive land on the wiring board, the solidification of the solder is prevented. Accordingly, a force in a direction away from each other is exerted on both terminal electrodes 4, but this force substantially only deforms the outer layer 7 and leaves little stress on the electronic component body 3. In addition, for example, dimensional changes due to thermal expansion and contraction on the wiring board side, which are likely to occur when mounted on an aluminum board, can be dealt with by deforming substantially only the outer layer 7.

According to this embodiment, as described above, since the edge of the inner layer 6 is covered with the outer layer 7, when the terminal electrode 4 is soldered to the wiring board, the solder is applied to the inner layer 6 and the outer layer. 7 can be reliably prevented from entering the gap 9. If the solder enters the gap 9, the movement of the outer layer 7 is hindered, and the deformation of the outer layer 7 as described above cannot be expected much.

The ceramic electronic component 1 can be manufactured as follows. First, the electronic component main body 3 is prepared, and an inner layer film made of a conductive paste that becomes the inner layer 6 by firing is formed on each end face of the electronic component main body 3. And then the applied conductive paste is dried. At this time, it is preferable to make the dip depth relatively shallow.

Next, in order to form the connection portion 8, a conductor made of, for example, a conductive paste is applied in a spot shape on the above-mentioned inner layer film, and then dried. Next, a burned-out film containing a substance that is burned off by firing is formed so as to cover at least the inner layer film except for a region where the connection portion 8 is to be formed. As a substance which is burned off by this firing, for example, oblate or carbon is used and handled as a paste. In addition, the burnt film is formed by an outer layer 7 described later.
Is preferably formed so as to extend beyond the position of the edge.

Next, an outer layer film made of a conductive paste that becomes the outer layer 7 by firing is formed so as to cover the burnt-out film. Thereafter, the above-mentioned inner layer film, burned-out film, and outer layer film are fired. As a result, the inner layer film becomes the inner layer 6, the outer layer film becomes the outer layer 7, and the burned-out film is burned out to form the gap 9. Thus, the ceramic electronic component 1 shown in FIG. 1 is obtained. In this ceramic electronic component 1, the outer layer 7 is preferably a thick film of, for example, about 10 to 60 μm. With such a thick film, the peeling of the outer layer 7 can be prevented in a plating step and a packaging step performed later, and the soldering to the wiring board or the expansion / contraction of the wiring board as described above. Outer layer 7 when
This is because cracking of the outer layer 7 can be advantageously prevented by the deformation of.

Note that the above-described firing step may be carried out separately into a firing step for the inner layer film and a firing step for the outer layer film and the burned-out film. Also, the inner layer 6 may be formed by a thin film forming technique such as sputtering, vapor deposition, or plating, instead of being formed with a thick film obtained by firing the conductive paste.

In the above-described manufacturing method, a conductor such as a conductive paste is separately provided in order to form the connection portion 8. However, instead of this, when forming a burnt film, simply In the region where the connection portion 8 is to be formed, this is not formed only. In this region, the outer layer film is brought into direct contact with the inner layer film, and the connection portion 8 is formed with a part of the outer layer film and / or the inner layer film. It may be.

As described above, if the conductor is positively applied to form the connection portion 8, the inner layer 6 can be formed.
Electrical connection between the inner layer 6 and the outer layer 7 can be ensured, and the mechanical bonding strength between the inner layer 6 and the outer layer 7 can be sufficiently ensured. Also, as shown in FIG. 1, the connecting portion 8 is not located at the center of the end surface of the electronic component body 3 in the surface direction, but may be provided at another position or distributed at a plurality of locations. It may be provided.

FIG. 3 is a diagram corresponding to FIG. 2 for explaining another embodiment of the present invention. In FIG. 3, FIG.
The same reference numerals are given to the elements corresponding to the elements shown in FIG. Referring to FIG.
A large number of particles 11 exist as inclusions between the outer layer 7 and the outer layer 7. These particles 11 are in a state of allowing a change in the distance between the inner layer 6 and the outer layer 7 and do not prevent the necessary deformation of the outer layer 7. Further, when the inner layer 6 and the outer layer 7 come into contact with each other, a current leaks between the inner layer 6 and the outer layer 7 and there is a possibility of thermal runaway. 7 are reliably prevented from contacting each other.

Since the particles 11 are present between the inner layer 6 and the outer layer 7 as described above, the particles 11 are made of a substance that remains even after being subjected to a firing step. It is previously contained in a paste for forming a film. As the particles 11, electrically insulating particles such as glassy particles or particles made of a metal oxide are advantageously used. Particularly preferably, when vitreous particles are contained in the conductive paste for forming the outer layer film,
The same thing as this is used as the particle 11.

FIG. 4 is a sectional view schematically showing a ceramic electronic component 1a according to still another embodiment of the present invention. In FIG. 4, elements corresponding to the elements shown in FIG. 1 are denoted by the same reference numerals, and redundant description will be omitted. The ceramic electronic component 1a includes a plurality of, for example, three electronic component bodies 3. The illustration of the internal structure of each electronic component body 3 is omitted. These electronic component bodies 3 are stacked with their respective end faces aligned in the plane direction.

The connecting portion 8 is formed so as to join the respective inner layers 6 of the electronic component body 3 to each other. In the process of manufacturing the ceramic electronic component 1 a, the conductive paste applied to form the connection portion 8 includes a plurality of electronic component main bodies 3.
After firing, the sintered connecting portions 8 join the respective inner layers 6 of the plurality of electronic component bodies 3 to each other, and firmly bond the electronic component bodies 3 to each other after firing. Acts to let.

The outer layer 7 is formed so as to cover each end face of the plurality of electronic component bodies 3 in common. Other structures and manufacturing methods of the ceramic electronic component 1a shown in FIG. 4 are substantially the same as those of the ceramic electronic component 1 shown in FIG. As described above, the embodiments of the present invention have been described in relation to the multilayer ceramic capacitor.
The present invention provides a ceramic electronic component having any structure or function as long as it is a ceramic electronic component including a chip-shaped electronic component body and terminal electrodes formed on at least each end face of the electronic component body. The same can be applied.

[0032]

As described above, according to the ceramic electronic component of the present invention, the stress exerted during the soldering to the wiring board or by the expansion and contraction of the wiring board is advantageous due to the deformation of the outer layer of the terminal electrode. And the stress applied to the electronic component body can be effectively reduced. Therefore, it is possible to prevent mechanical damage such as cracks from occurring in the electronic component body and the terminal electrodes.

Further, according to the ceramic electronic component of the present invention, it is not necessary to attach a terminal member made of a metal plate to the terminal electrode. For this reason, the operation and cost related to the terminal member are not bothered. Also, the problem of an increase in equivalent series resistance due to the attachment of the terminal member is not encountered. Further, problems that may occur in soldering the terminal member to the terminal electrode, for example, cracks occur in the electronic component body due to thermal shock applied at the time of soldering, flux residue occurs, or an organic solvent for removing flux All the problems that a cleaning step by such as becomes necessary can be solved.

In addition, since the mounting on the wiring board is performed by the terminal electrode itself irrespective of the terminal member, the degree of freedom of the mounting posture of the ceramic electronic component can be increased. Further, the outer layer of the terminal electrode has a fin effect for radiating heat of the electronic component body. For example, the radiating property of self-heating when used at a high frequency can be increased, and therefore, the allowable voltage can be increased. This effect is more remarkably exhibited particularly when a gap is formed between the inner layer and the outer layer.

In the ceramic electronic component according to the present invention, the terminal electrode has an adjacent surface extension extending to an adjacent surface adjacent to the end surface of the electronic component main body. If the distance between the end face of the main body is longer than the distance between the edge of the inner layer and the end face of the electronic component body, the solder applied at the time of soldering to the wiring board will be between the inner layer and the outer layer. Intrusion can be prevented.
Therefore, the necessary deformation of the outer layer is prevented from being hindered by such solder.

In the ceramic electronic component according to the present invention, if the outer layer is formed of a conductive thick film obtained by firing the conductive paste, the outer layer is undesirably peeled off or a crack is generated in the outer layer. Can be more reliably prevented. In the ceramic electronic component according to the present invention, when the connection portion for partially joining the inner layer and the outer layer to each other is located at the center of the end surface of the electronic component body in the surface direction, the allowable range of deformation of the outer layer Can be further expanded, and the electronic component body can be less likely to receive an undesired stress.

In the ceramic electronic component according to the present invention, if there are a large number of inclusions such as particles between the inner layer and the outer layer, the contact between the inner layer and the outer layer is prevented, so that the inner layer and the outer layer are not connected to each other. Current leaks between them, and thermal runaway can be reliably prevented. The ceramic electronic component according to the present invention includes a plurality of electronic component bodies, and when these electronic component bodies are stacked with their respective end faces aligned in the plane direction, the connection portion is provided on each of the plurality of electronic component bodies. When the inner layers are formed so as to be joined to each other, the connecting portion can act to firmly couple the plurality of electronic component bodies to each other.

According to the method for manufacturing a ceramic electronic component of the present invention, since the terminal electrode has at least a two-layer structure of an inner layer and an outer layer, a burned-out film containing a substance which is burned off by firing is applied. After forming an outer layer film made of a conductive paste to be an outer layer by firing, in the step of firing this outer layer film, simultaneously firing the burned-out film,
A structure in which the inner layer and the outer layer are only partially joined to each other can be efficiently obtained.

Further, if the burned-out film contains particles or the like of a substance remaining after firing, as described above, a structure in which a large number of particles-like inclusions exist between the inner layer and the outer layer is obtained. Can be easily obtained. At this time, if particles of the same quality as the particles of the remaining substance are also contained in the outer layer film, it becomes easier to uniformly include a large number of particles and other inclusions between the inner layer and the outer layer.

In order to form a connecting portion for partially joining the inner layer and the outer layer, if a conductor is partially provided on the inner layer, electrical connection between the inner layer and the outer layer can be ensured. And the mechanical bonding strength between the inner layer and the outer layer can be sufficiently ensured.

[Brief description of the drawings]

FIG. 1 is a sectional view schematically showing a ceramic electronic component 1 according to an embodiment of the present invention.

FIG. 2 is an enlarged view of a portion II shown in FIG.

FIG. 3 is a view for explaining another embodiment of the present invention;
FIG.

FIG. 4 is a sectional view schematically showing a ceramic electronic component 1a according to still another embodiment of the present invention.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1, 1a Ceramic electronic component 3 Electronic component main body 4 Terminal electrode 6 Inner layer 7 Outer layer 8 Connecting part 9 Gap 10 Adjacent surface extension 11 Particle a Distance between edge of outer layer and end of electronic component body b Edge of inner layer And the distance between the end face of the electronic component body

Claims (11)

[Claims] 1. An electronic component main body having a chip shape and terminal electrodes formed on at least each end face of the electronic component main body, wherein the terminal electrodes are partially connected to each other via a conductive connection portion. A ceramic electronic component having at least a two-layer structure having an inner layer and an outer layer joined to a ceramic electronic component. 2. The electronic device according to claim 2, wherein the terminal electrode has an adjacent surface extension extending to an adjacent surface adjacent to the end surface of the electronic component main body. 2. The ceramic electronic component according to claim 1, wherein a distance between them is longer than a distance between an edge of the inner layer and the end face. 3. 3. The ceramic electronic component according to claim 1, wherein the outer layer is formed of a conductive thick film obtained by firing a conductive paste. 4. The ceramic electronic component according to claim 1, wherein the connection portion is located at a center in a surface direction of each of the end surfaces of the electronic component main body. 5. The ceramic electronic component according to claim 1, wherein a gap is formed between said inner layer and said outer layer. 6. The ceramic according to claim 1, wherein an inclusion is present between the inner layer and the outer layer in a state that allows a change in the space between the inner layer and the outer layer. Electronic components. 7. A plurality of electronic component main bodies, wherein the plurality of electronic component main bodies are stacked with their respective end faces aligned in a plane direction, and the connecting portion is connected to the plurality of electronic component main bodies. 2. The outer layer is formed so as to bond the respective inner layers to each other, and the outer layer is formed so as to commonly cover the respective end faces of the plurality of electronic component bodies.
7. The ceramic electronic component according to any one of claims 6 to 6. 8. An electronic component body having a chip shape, and terminal electrodes formed on at least each end face of the electronic component body, wherein the terminal electrodes are partially connected to each other via a conductive connection portion. A method of manufacturing a ceramic electronic component having at least a two-layer structure having an inner layer and an outer layer joined to each other, comprising: a step of preparing the electronic component body; Forming the inner layer, excluding a region where the connection portion is to be formed, and forming a burned film containing a substance that is burned off by firing, so as to cover at least the inner layer; and to cover the burned film. A step of forming an outer layer film made of a conductive paste to be the outer layer by firing; and a step of firing the burned-out film and the outer layer film. Method. 9. The method for manufacturing a ceramic electronic component according to claim 8, wherein the burnt-out film contains particles of a material remaining after firing in addition to the material to be burned off. 10. The method for manufacturing a ceramic electronic component according to claim 9, wherein particles of the same quality as the particles of the remaining substance are also contained in the outer layer film. 11. The method for manufacturing a ceramic electronic component according to claim 8, further comprising a step of partially providing a conductor on said inner layer to form said connection portion.