JP4844317B2 - Ceramic electronic component and manufacturing method thereof - Google Patents

Description

  The present invention relates to a ceramic electronic component and a manufacturing method thereof, and more particularly to a structure and a manufacturing method of a surface electrode formed along the surface of a ceramic electronic component.

  As a ceramic electronic component which is interesting for the present invention, there is one having a structure in which a surface electrode is formed along the surface of a ceramic body, such as a multilayer ceramic substrate. In the structure of such a ceramic electronic component, since ceramic and metal generally have a property of being difficult to bond to each other, it is relatively difficult to obtain sufficient bonding strength between the ceramic body and the surface electrode. It's not easy. In order to solve this problem, the following techniques have been proposed.

  For example, in JP-A-8-181441 (Patent Document 1), a surface electrode formed along the surface of a ceramic body is disposed so as to be in contact with the ceramic body, and is mainly composed of copper, such as alumina. The first layer is configured to include such a bonding reinforcing agent, and the second layer is formed on the first layer and includes the second layer that is mainly composed of copper and does not include the bonding reinforcing agent. Are listed.

  Next, in Japanese Patent Laid-Open No. 2001-326301 (Patent Document 2), a surface electrode formed on the surface of a ceramic body is formed so as to be in contact with the ceramic body, and the conductive component and the ceramic body are configured. It is described that it comprises a first layer including a ceramic component having the same composition system as the ceramic to be formed, and a second layer formed on the first layer and including a conductive component and a glass component.

  Next, in Japanese Patent Application Laid-Open No. 61-284959 (Patent Document 3), the surface electrode formed on the surface of the ceramic body is made of a mixture of a conductive material and the same material as the ceramic body. Are listed.

  However, each technique described in Patent Documents 1 to 3 has a problem to be solved.

  That is, in the one described in Patent Document 1, the content of the bonding reinforcing agent contained in the first layer, in the one described in Patent Document 2, the content of the ceramic component contained in the first layer, and the patent In the material described in Document 3, the bonding strength can be increased as the content of the same material as the ceramic body included in the surface electrode is increased. In other words, sufficient bonding strength cannot be obtained unless the content of the bonding reinforcing agent or ceramic component is increased to some extent.

As described above, when the content of the bonding reinforcing agent or the ceramic component is increased, the plating impartability is lowered and the conductivity is lowered. More specifically, in the materials described in Patent Documents 1 and 2, the conductivity of the first layer is lowered, and in the material described in Patent Document 3, the conductivity of the entire surface electrode is lowered. However, even if the electrical conductivity of the first layer or the entire surface electrode is lowered, the electrical characteristics are deteriorated because the electrical conductivity is maintained somewhat.
JP-A-8-181441 JP 2001-326301 A Japanese Patent Laid-Open No. 61-284959

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

The present invention is first directed to a ceramic electronic component including a ceramic body made of a low-temperature sintered ceramic and a surface electrode formed along the surface of the ceramic body. In order to solve the above-mentioned technical problem, in the present invention, the surface electrode is formed so as to be in contact with the ceramic body, is mainly composed of a low-temperature sintered ceramic having substantially the same composition as the low-temperature sintered ceramic, and a metal. An underlayer comprising an oxide as a subcomponent, and a surface layer formed on the underlayer, comprising a low melting point metal as a main component and a metal oxide having the same composition as the metal oxide as a subcomponent. Yes, and the metal oxide is characterized in that is unevenly distributed in the vicinity of the interface between the surface layer and the underlying layer.

The metal oxide in the underlayer and the surface layer is at least one metal oxide selected from the group consisting of Al ₂ O ₃ , ZrO ₂ , TiO ₂ , SiO ₂ , Nb ₂ O ₅ and Ta ₂ O _5. Preferably there is.

  The metal oxide content in the surface layer is preferably 1 to 12% by weight, and the metal oxide content in the underlayer is preferably 0.1 to 20% by weight.

  The low melting point metal in the surface layer is preferably at least one low melting point metal selected from the group consisting of Ag, Cu, Au and Ni.

  The thickness of the surface layer is preferably 1 to 50 μm, and the thickness of the underlayer is preferably 1 to 10 μm.

  In the ceramic electronic component according to the present invention, it is preferable that at least a part of the surface side peripheral portion of the surface layer is covered with a protective layer having substantially the same composition as that of the base layer.

  Moreover, it is preferable that the ceramic body provided in the ceramic electronic component according to the present invention has a laminated structure in which a plurality of low-temperature sintered ceramic layers made of low-temperature sintered ceramics are laminated.

  The ceramic electronic component according to the present invention may further include a surface mount electronic component mounted via a surface layer.

The present invention is also directed to a method of manufacturing a ceramic electronic component as described above. The method for manufacturing a ceramic electronic component according to the present invention includes a step of preparing an unfired ceramic body including a low-temperature sintered ceramic powder, and substantially the same as the low-temperature sintered ceramic powder on the surface of the unfired ceramic body. A step of forming an unfired underlayer comprising a low-temperature sintered ceramic powder of a composition as a main component and a metal oxide powder as a subcomponent, and a low-melting-point metal powder as a main component on the unfired underlayer; A step of forming an unfired surface layer using a metal oxide powder of the same composition as the metal oxide powder as a subcomponent, and firing to sinter the unfired ceramic body, unfired underlayer and unfired surface layer In this firing step, the metal oxide derived from the metal oxide powder is near the interface between the surface layer derived from the unfired surface layer and the foundation layer derived from the unfired foundation layer. Are unevenly distributed It is characterized in that it is in.

  According to the present invention, the surface electrode has a base layer formed so as to be in contact with the ceramic body and a surface layer formed on the base layer, and the base layer constitutes the ceramic body at a low temperature. Since the main component is a low-temperature sintered ceramic having substantially the same composition as the ceramic, and both the underlayer and the surface layer contain metal oxides having the same composition as subcomponents, the surface electrode and the ceramic body The difference in shrinkage behavior between the surface electrode and the ceramic body can be reduced, and an anchor can be formed. From these things, the surface electrode can implement | achieve high joint strength with respect to a ceramic body.

  In addition, since the underlying layer itself in the surface electrode is an insulator, the electrical characteristics are not deteriorated by the underlying layer.

  In addition, since the high bonding strength as described above is obtained by the presence of the underlayer, the content of the metal oxide contained in the surface layer can be reduced, and therefore, good plating impartability in the surface layer. And high conductivity can be obtained.

  In this invention, when at least a part of the surface side peripheral portion of the surface layer is covered with a protective layer having substantially the same composition as the underlayer, the bonding strength of the surface electrode can be further increased.

  FIG. 1 is a cross-sectional view for explaining a ceramic electronic component and a method for manufacturing the same according to a first embodiment of the present invention. In FIG. 1, (A) shows an unfired ceramic electronic component 1a in an unfired stage, and (B) shows a post-sintering obtained by firing the unfired ceramic electronic component 1a shown in (A). The ceramic electronic component 1 is shown.

  Referring to FIG. 1B, a ceramic electronic component 1 includes a ceramic body 2 made of a sintered body of low-temperature sintered ceramic, and a surface electrode 3 formed along the surface of the ceramic body 2. ing. The surface electrode 3 has a base layer 4 formed so as to be in contact with the ceramic body 2 and a surface layer 5 formed on the base layer 4.

The low-temperature sintered ceramic constituting the ceramic body 2 is a ceramic that can be sintered at a temperature of 1050 ° C. or lower and that can be fired simultaneously with a low-melting-point metal such as Au, Ag, Cu, or Ni. Specific examples of the low-temperature sintered ceramic material include: (1) a glass composite low-temperature sintered ceramic material obtained by mixing glass powder such as borosilicate glass with ceramic powder such as alumina, zirconia, magnesia, and forsterite; (2) Crystallized glass-based low-temperature sintered ceramic materials such as ZnO—MgO—Al ₂ O ₃ —SiO ₂ -based crystallized glass, (3) BaO—Al ₂ O ₃ —SiO ₂ -based ceramic powder and Al ₂ O ₃ there are _{-CaO-SiO 2 -MgO-B 2} O 3 based ceramic non-glass-based low-temperature co-fired ceramic material, such as powder. The low-temperature sintered ceramic powder is generally a composite powder obtained by mixing and calcining a plurality of raw material compositions, and is different from the “metal oxide powder” in this respect.

  In the surface electrode 3, the underlayer 4 is mainly composed of a low-temperature sintered ceramic having the same composition as that of the low-temperature sintered ceramic constituting the ceramic body 2, and a metal oxide as a subcomponent. In addition, the low-temperature sintered ceramic having substantially the same composition as the low-temperature sintered ceramic constituting the ceramic body 2 has the same main constituent elements of the low-temperature sintered ceramic constituting the ceramic body 2 and the composition ratio thereof This is the same low temperature sintered ceramic.

  As described above, the base layer 4 may be composed mainly of a low-temperature sintered ceramic and a metal oxide as a minor component. For example, a mixed powder of a low-temperature sintered ceramic powder and a metal oxide powder is sintered. Even a layer obtained by sintering a powder obtained by coating the surface of a low-temperature sintered ceramic powder with a metal oxide may be used.

  In the surface electrode 3, the surface layer 5 contains a metal oxide having the same composition as that of the metal oxide contained in the underlayer 4 while having a low melting point metal as a main component. As described above, the surface layer 5 only needs to have a low melting point metal as a main component and a metal oxide as a subcomponent, and can be obtained by, for example, sintering a mixed powder of a low melting point metal powder and a metal oxide powder. Even a layer obtained by sintering a powder obtained by coating a metal oxide on the surface of a low melting point metal powder may be used.

The metal oxide contained as a subcomponent in the underlayer 4 and the surface layer 5 is at least one selected from the group consisting of Al ₂ O ₃ , ZrO ₂ , TiO ₂ , SiO ₂ , Nb ₂ O ₅ and Ta ₂ O _5. A seed metal oxide is preferred. These metal oxides delay the sintering of the low melting point metal in the surface layer 5 and promote the sintering of the low temperature sintered ceramic in the underlayer 4. This acts to match the shrinkage behavior of the ceramic body 2 and the surface layer 5. Note that Al ₂ O ₃ is particularly preferable as the metal oxide.

  The content ratio of the metal oxide in the surface layer 5 is preferably as small as possible in terms of conductivity, but if it is too small, the bonding strength with the ceramic body 2 is lowered. In this respect, the content ratio of the metal oxide in the surface layer 5 is preferably 1 to 12% by weight. In this invention, even if the content ratio of the metal oxide in the surface layer 5 is small as described above, the surface electrode 3 has a multilayer structure in which the underlayer 4 is also formed. The bonding strength can be kept sufficiently. When the content ratio of the metal oxide in the surface layer 5 is less than 1% by weight, it tends to be difficult to ensure sufficient bonding strength with the ceramic body 2, while when it exceeds 12% by weight, When the electrical conductivity of the surface layer 5 is reduced and directed to high frequency applications, the high frequency characteristics tend to be hindered.

  The content ratio of the metal oxide in the underlayer 4 is such an amount as to alleviate the difference in shrinkage behavior between the material constituting the ceramic body 2 and the material constituting the surface layer 5, specifically 0 It is preferably 1 to 20% by weight. If this content is less than 0.1% by weight, it becomes difficult to alleviate the difference in shrinkage behavior, and the bonding strength between the underlayer 4 and the surface layer 5 decreases, resulting in a surface electrode. 3 and the ceramic body 2 tend to decrease in bonding strength. On the other hand, if the content exceeds 20% by weight, it becomes difficult to alleviate the difference in shrinkage behavior, and the base layer 4 and the ceramic body 2 As a result, the bonding strength between the surface electrode 3 and the ceramic body 2 tends to decrease.

  As the low melting point metal contained in the surface layer 5 as a main component, typically, at least one selected from the group consisting of Ag, Cu, Au and Ni is used. Since these metals have high electrical conductivity, it is possible to form a conductor pattern having excellent electrical characteristics particularly in a high frequency band.

  The thickness of a normal surface electrode is about 1 to 10 μm. This is because if the surface electrode becomes too thick, defects (peeling, etc.) based on the difference in shrinkage behavior from the ceramic body tend to occur. On the other hand, according to this invention, even if the thickness of the surface layer 5 is 10 μm or more, and even 20 μm or more, the bonding strength with the ceramic body 2 is excellent even if it is extremely thick. Such defects are less likely to occur. If the thickness of the surface layer 5 exceeds 50 μm, patterning of the surface layer 5 becomes difficult.

  The thickness of the underlayer 4 is preferably 1 to 10 μm. If the thickness is less than 1 μm, it will be difficult to sufficiently exert the role as the underlayer 4, while if it exceeds 10 μm, patterning tends to be difficult. The thickness of the surface layer 5 is preferably thicker than the thickness of the underlayer 4. This is because the electrical conductivity increases as the thickness of the surface layer 5 increases.

  In order to obtain the ceramic electronic component 1 shown in FIG. 1B, the unfired ceramic electronic component 1a shown in FIG. 1A is produced. The unfired ceramic electronic component 1a includes the unfired ceramic body 2a, the unfired underlayer 4a, and the unfired surface layer 5a, which become the ceramic body 2, the underlayer 4, and the surface layer 5, respectively.

The unfired ceramic body 2a is composed of an aggregate of low-temperature sintered ceramic powder such as BaO—Al ₂ O ₃ —SiO ₂ ceramic powder. More specifically, a low-temperature sintered ceramic powder, an organic binder such as polyvinyl butyral, a solvent such as toluene and isopropyl alcohol, a plasticizer such as di-n-butyl phthalate, and the like, if necessary. Then, an unfired ceramic body 2a is obtained by passing through each step of adding an additive such as a dispersant to form a slurry and shaping the obtained slurry by applying, for example, a doctor blade method.

The unfired underlayer 4a is made of a low-temperature sintered ceramic powder having substantially the same composition as that of the low-temperature sintered ceramic powder contained in the unfired ceramic body 2a such as BaO—Al ₂ O ₃ —SiO ₂ ceramic powder. The main component is a metal oxide powder such as Al ₂ O ₃ powder. The unfired surface layer 5a is mainly composed of a low-melting-point metal powder such as Ag powder, and a metal oxide powder having the same composition as the metal oxide powder contained in the unfired underlayer 4a such as Al ₂ O _3. Is a subcomponent.

More specifically, the unfired underlayer 4a is composed of a low-temperature sintered ceramic powder and a metal oxide powder, an organic binder such as ethyl cellulose, acrylic resin, polyvinyl butyral, and methacrylic resin, terediol, butyl carbitol, and butyl carbyl. It is formed by adding a solvent such as tall acetate or alcohol to form a paste, and printing this paste on the surface of the unfired ceramic body 2a. The viscosity of the paste is preferably 10 to 700 Pa · s ⁻¹ in order to obtain good printability. In the paste, the organic vehicle comprising an organic binder and a solvent is preferably in the range of 10 to 55% by weight.

  The unfired surface layer 5a also includes a low-melting point metal powder instead of the low-temperature sintered ceramic powder in the unfired underlayer 4a described above, and is formed by printing on the unfired underlayer 4a. This is substantially the same as in the case of the unfired underlayer 4a.

  The green ceramic body 2a, the green base layer 4a and the green surface layer 5a shown in FIG. 1A are fired at a temperature of 1050 ° C. or lower. Thus, the fired ceramic electronic component 1 shown in FIG. 1B is obtained.

  In FIG. 1A, the metal oxide 6 contained in both the unfired underlayer 4a and the unfired surface layer 5a is schematically illustrated as spherical particles. Before firing, as shown in FIG. 1A, the metal oxide 6 is uniformly dispersed in the unfired underlayer 4a and the unfired surface layer 5a. However, in the firing step described above, the metal oxide 6 moves so as to gather near the interface between the unfired underlayer 4a and the unfired surface layer 5a, and after firing, as shown in FIG. The metal oxide 6 is unevenly distributed near the interface between the base layer 4 and the surface layer 5.

  This is because the low melting point metal contained in the unfired surface layer 5a begins necking (that is, begins to sinter) between the metal powders, and the low-temperature sintered ceramic contained in the unfired underlayer 4a becomes the unfired ceramic body. This is because necking is started (that is, sintering) is performed between the low-temperature sintered ceramic powders with the same profile as that of the low-temperature sintered ceramic included in 2a. As a result, after sintering, the metal oxide 6 gathers in the vicinity of the interface between the underlayer 4 and the surface layer 5, and due to the anchor effect of the metal oxide 6 belonging to each of the underlayer 4 and the surface layer 5, A state is obtained in which the base layer 4 and the surface layer 5 are firmly bonded to each other.

In FIG. 1B, the metal oxide 6 is illustrated in the form of particles, but this is only schematically shown. When the metal oxide 6 is, for example, Al ₂ O ₃ , it is known that part or all of the metal oxide 6 is vitrified after firing.

  Further, after firing, the interface between the base layer 4 and the surface layer 5 does not appear as clearly as shown in FIG. Further, when attention is paid to the distribution density of the metal oxide 6, the surface electrode 3 after firing can be said to have a three-layer structure including a sparse layer, a dense layer, and a sparse layer.

  FIG. 2 is a sectional view showing a ceramic electronic component 11 according to the second embodiment of the present invention. 2, elements corresponding to the elements shown in FIG. 1B are denoted by the same reference numerals, and redundant description is omitted.

  In the ceramic electronic component 1 shown in FIG. 1, in the surface electrode 3, the base layer 4 and the surface layer 5 have the same planar shape and have substantially the same area as each other. In the electronic component 11, in the surface electrode 3, the base layer 4 has a planar shape similar to the planar shape of the surface layer 5, but has a larger area than the surface layer 5. In other words, the outer peripheral edge of the foundation layer 4 is characterized by being located outside the outer peripheral edge of the surface layer 5.

  This can reliably prevent the surface layer 5 from coming into direct contact with the ceramic body 2. If a contact portion between the surface layer 5 and the ceramic body 2 is formed, a crack or the like enters from there, and as a result, the bonding strength of the surface layer 5 may be lowered, which is not preferable.

  FIG. 3 is a sectional view showing a ceramic electronic component 11a according to the third embodiment of the present invention. The third embodiment shown in FIG. 3 corresponds to a modification of the second embodiment shown in FIG. 3, elements corresponding to those shown in FIG. 2 are denoted by the same reference numerals, and redundant description is omitted.

  The ceramic electronic component 11a shown in FIG. 3 is characterized in that the surface electrode 3 is formed so as to be embedded in the ceramic body 2 as compared with the ceramic electronic component 11 shown in FIG. When the ceramic body 2 is a laminated body, for example, an unfired underlayer to be the underlayer 4 and an unfired surface to be the surface layer 5 on the unfired ceramic body in the unfired stage of the ceramic body 2 After the layer is formed, in order to make the laminated structure of the unfired ceramic body more dense, it is usually pressed in the laminating direction before the firing step. By this pressing, the green base layer and the green surface layer are embedded in the green ceramic body. As a result, the surface electrode 3 is embedded in the ceramic body 2 in the fired ceramic electronic component 11a.

  FIG. 4 is a sectional view showing a ceramic electronic component 21 according to the fourth embodiment of the present invention. In FIG. 4, elements corresponding to those shown in FIG. 1 or FIG.

  In the ceramic electronic component 21 shown in FIG. 4, at least a part of the surface side peripheral portion of the surface layer 5 in the surface electrode 3 is covered with a protective layer 22 having substantially the same composition as the underlayer 4. It is said. According to such a structure, since the surface layer 5 is pressed by the protective layer 22, the bonding strength of the surface layer 5 can be further improved, and cracks can be generated from the interface between the surface layer 5 and the underlayer 4. Etc. can be reduced.

  FIG. 5 is a sectional view showing a ceramic electronic component 21a according to the fifth embodiment of the present invention. The fifth embodiment shown in FIG. 5 corresponds to a modification of the fourth embodiment shown in FIG. In FIG. 5, elements corresponding to those shown in FIG. 4 are denoted by the same reference numerals, and redundant description is omitted.

  The ceramic electronic component 21a shown in FIG. 5 is characterized in that the surface electrode 3 is formed so as to be embedded in the ceramic body 2 as compared with the ceramic electronic component 21 shown in FIG. That is, it has the same characteristics as the ceramic electronic component 11a shown in FIG. Also in the case of the ceramic electronic component 21 a shown in FIG. 5, an unfired underlayer to be the underlayer 4 and an unfired surface layer 5 on the unfired ceramic body in the unfired stage of the ceramic body 2. After the unfired protective layer to be the fired surface layer and the protective layer 22 is formed, the unfired underlayer, the unfired surface layer, and the unfired protective layer are formed in the unfired ceramic body by pressing in the stacking direction. As a result, the surface electrode 3 is embedded in the ceramic body 2 in the fired ceramic electronic component 21a.

  FIG. 6 is a sectional view showing a ceramic electronic component 31 according to a sixth embodiment of the present invention.

  A ceramic electronic component 31 shown in FIG. 6 constitutes a multilayer ceramic substrate, and includes a ceramic body 33 having a laminated structure in which a plurality of low-temperature sintered ceramic layers 32 made of low-temperature sintered ceramics are laminated. Yes. Various conductor patterns are provided in connection with specific ones of the ceramic layers 32.

  The conductor pattern described above is formed along a specific interface between the several surface electrodes 34 and 35 and the ceramic layer 32 respectively formed on the end faces located at both ends in the stacking direction of the ceramic body 33. There are several internal conductor films 36, as well as several via-hole conductors 37 that are formed to penetrate certain ones of the ceramic layers 32.

  The surface electrode 34 described above is used for electrical connection to surface mount electronic components 38 and 39 to be mounted on the outer surface of the ceramic body 33, as shown in FIG. The surface-mounted electronic component 38 is, for example, a chip capacitor, and includes a planar terminal electrode 40, and this terminal electrode 40 is electrically connected to the surface electrode 34 via a solder 41. The surface mount electronic component 39 is, for example, a semiconductor IC and includes a bump electrode 42, and the bump electrode 42 is electrically connected to the surface electrode 34.

  As shown in FIG. 7, the surface electrode 35 is used for electrical connection to a mother board 43 on which the ceramic electronic component 31 is mounted. More specifically, the surface electrode 35 is electrically connected to the conductive land 44 formed on the mother board 43 via the solder 45.

  With reference to FIG. 6 again, the manufacturing method of the ceramic electronic component 31 will be described.

  The ceramic body 33 provided in the ceramic electronic component 31 is a surface electrode 34 formed by respectively forming an unfired ceramic body made of a plurality of laminated unfired ceramic layers to be the low-temperature sintered ceramic layer 32 with a conductive paste. And 35, together with the inner conductor film 36 and the via-hole conductor 37, it is obtained by firing.

  The laminated structure of the unfired ceramic layer in the unfired ceramic body described above is typically provided by laminating a plurality of ceramic green sheets obtained by molding a slurry containing low-temperature sintered ceramic powder. The conductor pattern, particularly the inner conductor pattern, is provided on the ceramic green sheet before lamination. When the conductive pattern is provided on the ceramic green sheet, a conductive paste is used. A through hole for the via-hole conductor 37 is provided in the ceramic green sheet. The through hole is filled with the conductive paste, and the internal conductor film 36 is provided. For example, a conductive paste film is formed by screen printing. The surface electrodes 34 and 35 may also be formed at this stage. As shown in FIG. 1, the surface electrodes 34 and 35 are formed with a two-layer structure having an unfired underlayer 4a and an unfired surface layer 5a.

  As the conductive metal contained in each of the conductive paste used for forming the above-described inner conductor film 36 and via-hole conductor 37 and the conductive paste used for forming the unfired surface layer of the surface electrodes 34 and 35. Can advantageously use at least one low melting point metal selected from the group consisting of Ag, Cu, Au and Ni.

  Next, an unfired ceramic body is obtained by laminating a plurality of ceramic green sheets in a predetermined order and pressing them in the laminating direction. The step of forming the green base layer and the green surface layer for the surface electrodes 34 and 35 described above may be performed after the green ceramic body is obtained.

  Thereafter, the unfired ceramic body is fired, whereby the fired ceramic body 33 is obtained. Thereafter, surface-mounted electronic components 38 and 39 are mounted on the ceramic body 33 as necessary.

  Next, experimental examples carried out to confirm the effects of the present invention will be described.

  First, an evaluation sample according to each of Comparative Examples 1 and 2 deviating from the scope of the present invention and an evaluation sample according to an example within the scope of the present invention were prepared as follows.

(Comparative Example 1)
On a ceramic body made of low-temperature sintered ceramic, a Cu powder having an average particle diameter of 3 μm as a solid content and a ceramic powder having the same composition as the ceramic constituting the ceramic body having an average particle diameter of 1 μm in a weight ratio of 50:50 A paste containing only a Cu powder having an average particle size of 3 μm as a solid content was printed on the unfired undercoat layer to form an unfired surface layer. Thereafter, the sample for evaluation according to Comparative Example 1 in which the surface electrode was formed on the ceramic body was obtained by firing. In this evaluation sample, the sintered base layer has a thickness of 2.5 μm and an area of 2 mm × 2 mm, and the surface layer has a thickness of 4 μm and an area of 1.8 mm × 1.8 mm. It was.

(Comparative Example 2)
A paste containing a Cu powder having an average particle diameter of 3 μm and an Al ₂ O ₃ powder having an average particle diameter of 1 μm in a weight ratio of 93: 7 as a solid content is printed on a ceramic body made of low-temperature sintered ceramic. After forming the fired surface electrode, the sample for evaluation according to Comparative Example 2 in which the surface electrode was formed on the ceramic body was obtained by firing. In this evaluation sample, the sintered surface electrode had a thickness of 4 μm and an area of 2 mm × 2 mm.

(Example)
On a ceramic body made of low-temperature sintered ceramic, a ceramic powder having the same composition as that of a ceramic body having an average particle diameter of 1 μm as a solid content and an Al ₂ O ₃ powder having an average particle diameter of 1 μm of 95: 5 A paste containing a weight ratio is printed to form an unfired underlayer, and then, on the unfired underlayer, a Cu powder having an average particle diameter of 3 μm and an Al ₂ O ₃ powder having an average particle diameter of 1 μm as a solid content. A paste containing 93: 7 by weight was printed to form an unfired surface layer, and then fired to obtain a sample for evaluation according to an example in which surface electrodes were formed on the ceramic body. . In this evaluation sample, the sintered base layer has a thickness of 2.5 μm and an area of 2.2 mm × 2.2 mm, and the surface layer has a thickness of 4 μm and an area of 2 mm × 2 mm. It was.

(Evaluation)
For the evaluation samples according to each of Comparative Example 1, Comparative Example 2, and Examples obtained as described above, the bonding strength of the surface electrode was evaluated by a tensile strength test. The results are shown in Table 1.

  As can be seen from Table 1, according to the example, higher bonding strength than those of Comparative Examples 1 and 2 is obtained.

BRIEF DESCRIPTION OF THE DRAWINGS It is for demonstrating 1st Embodiment of this invention, (A) is sectional drawing which shows the unfired ceramic electronic component 1a in an unfired stage, (B) is the unfired shown to (A) It is sectional drawing which shows the ceramic electronic component 1 after the sintering obtained by baking the ceramic electronic component 1a. It is sectional drawing which shows the ceramic electronic component 11 by 2nd Embodiment of this invention. It is sectional drawing which shows the ceramic electronic component 11a by 3rd Embodiment of this invention. It is sectional drawing which shows the ceramic electronic component 21 by 4th Embodiment of this invention. It is sectional drawing which shows the ceramic electronic component 21a by 5th Embodiment of this invention. It is sectional drawing which shows the ceramic electronic component 31 by 6th Embodiment of this invention. 7 is a cross-sectional view showing a state in which surface-mounted electronic components 38 and 39 are mounted on the ceramic electronic component 31 shown in FIG. 6 and the ceramic electronic component 31 is mounted on a motherboard 43. FIG.

Explanation of symbols

1,11,11a, 21,21a, 31 Ceramic electronic component 1a Unfired ceramic electronic component 2,33 Ceramic body 2a Unfired ceramic body 3,34,35 Surface electrode 4 Underlayer 4a Unfired underlayer 5 Surface layer 5a Unsintered surface layer 6 Metal oxide 22 Protective layer 32 Low-temperature sintered ceramic layer 38, 39 Surface mount type electronic component

Claims (11)

A ceramic body made of low-temperature sintered ceramic, and a surface electrode formed along the surface of the ceramic body,
The surface electrode is formed so as to be in contact with the ceramic element body, and comprises a base layer comprising a low-temperature sintered ceramic having substantially the same composition as the low-temperature sintered ceramic as a main component and a metal oxide as a subcomponent. the formed on an underlying layer, as a main component low-melting metal, and to the metal oxide having the same composition of metal oxides as subcomponent, it has a surface layer,
The metal oxide is unevenly distributed in the vicinity of the interface between the surface layer and the base layer.
Ceramic electronic components. The metal oxide in the underlayer and the surface layer is at least one metal oxide selected from the group consisting of Al ₂ O ₃ , ZrO ₂ , TiO ₂ , SiO ₂ , Nb ₂ O ₅ and Ta ₂ O _5. The ceramic electronic component according to claim 1, wherein the ceramic electronic component is a product.   The ceramic electronic component according to claim 1 or 2, wherein a content ratio of the metal oxide in the surface layer is 1 to 12% by weight.   The ceramic electronic component according to any one of claims 1 to 3, wherein a content ratio of the metal oxide in the underlayer is 0.1 to 20% by weight.   5. The ceramic electronic component according to claim 1, wherein the low melting point metal in the surface layer is at least one low melting point metal selected from the group consisting of Ag, Cu, Au, and Ni.   The ceramic electronic component according to claim 1, wherein the surface layer has a thickness of 1 to 50 μm.   The ceramic electronic component according to claim 1, wherein the foundation layer has a thickness of 1 to 10 μm. At least a portion of the surface side peripheral edge portion of the surface layer, the covered by the underlying layer and the protective layer of substantially the same composition, the ceramic electronic component according to any one of claims 1 to 7. The ceramic body has a laminated structure formed by laminating a plurality of low temperature sintering ceramic layers made of low temperature co-fired ceramic, ceramic electronic component according to any one of claims 1 to 8. The ceramic electronic component according to any one of claims 1 to 9 , further comprising a surface-mounted electronic component mounted via the surface layer. Preparing a green ceramic body containing low-temperature sintered ceramic powder;
On the surface of the unfired ceramic body, an unfired underlayer is formed, the main component of which is a low-temperature sintered ceramic powder having substantially the same composition as the low-temperature sintered ceramic powder, and the metal oxide powder is a minor component. And a process of
On the unfired underlayer, a step of forming an unfired surface layer comprising a low melting point metal powder as a main component and a metal oxide powder having the same composition as the metal oxide powder as a subcomponent;
In order to sinter the unfired ceramic body, the unfired underlayer and the unfired surface layer, and a step of firing ,
In the firing step, the metal oxide derived from the metal oxide powder is unevenly distributed near the interface between the surface layer derived from the unfired surface layer and the foundation layer derived from the unfired foundation layer. The
Manufacturing method of ceramic electronic components.

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