JP6879885B2 - Conductive paste for forming external electrodes of laminated chip parts and laminated chip parts - Google Patents

Description

The present invention relates to a conductive paste used for forming an external electrode of a laminated chip component, and a laminated chip component including an external electrode formed by using the conductive paste and an internal electrode containing palladium.

In laminated chip components such as laminated chip capacitors, laminated chip varistores, laminated chip thermistors, and laminated piezoelectric elements, palladium (Pd) is used as the material for internal electrodes, and silver (Ag) is used as the material for external electrodes. The configuration is known.

In a general method for manufacturing such a laminated chip component, for example, a plurality of ceramic layers and a plurality of layers serving as internal electrodes are alternately laminated to form a ceramic laminate (ceramic laminate or ceramic element). Form. Since the edge (end face) of the internal electrode is exposed on the end side surface of the laminate, the outer electrode is formed by applying a conductive paste to the end side surface and firing. Here, it is known that when the conductive paste is fired, the internal electrode grows so as to protrude with respect to the external electrode (conductive paste) due to the Kirkendall effect / Kirkendall Effect.

When the internal electrode is "protruded" due to the Kirkendall effect in this way, the contact surface between the internal electrode and the external electrode, that is, the joint between the internal electrode and the external electrode, has a cavity called Kirkendall Void or a cavity. Voids may occur. It is considered that this is because a part of the external electrode is pushed up at the joint portion (in other words, the interface between the internal electrode and the external electrode) as the protruding portion of the internal electrode grows.

Conventionally, in the field of manufacturing laminated chip parts, as a technique for reducing the influence of the Kirkendar effect when forming contact between an internal electrode and an external electrode, for example, a method disclosed in Patent Documents 1 to 5 has been proposed. Has been done.

Patent Document 1 discloses a method of forming a glass layer by baking a glass paste containing 5 to 60% by volume of metal on a surface in which the edge of an internal electrode (including Pd) is exposed in a ceramic laminate. ing. In this method, the metal in the glass paste is moved to form an extension portion so as to penetrate the glass layer from the edge of the internal electrode and reach the surface of the glass layer by the Kirkendal effect.

Further, in Patent Document 2, the surface of the ceramic element is coated with a glass layer by applying and firing a glass paste, and on the side surface (end surface) of the end where the internal electrodes (including Ag and / or Pd) are exposed. A method for forming a base electrode (external electrode) is disclosed. In this method, the glass layer formed is provided with an opening in the exposed portion of the internal electrode in a self-aligned manner. At this opening, metal is supplied from the base electrode (external electrode) to the internal electrode, and the Kirkendall effect (“Kirkendall effect” in Patent Document 2) causes the end of the internal electrode to be the base electrode (external electrode). It sticks out toward and becomes thicker.

Further, in Patent Document 3, Ag and Pd are contained as metal components as a conductive paste for forming an external electrode on the end side surface (end face) of the ceramic element body on which the internal electrode (including at least Pd) is exposed. A method is disclosed in which crystallized glass is included as a glass component, and the ratio of the metal component and the ratio of the crystallized glass and the voids are set within a predetermined range. In this method, the diffusion of Ag is suppressed by using crystallized glass for the conductive paste, and the Ag of the conductive paste is diffused to the internal electrodes by setting the ratio of the metal component and the ratio of the crystallized glass and the voids. It suppresses doing.

Further, in Patent Document 4, as a conductive paste for forming an external electrode on the end side surface (end face) of the ceramic element body on which the internal electrode (including at least Pd) is exposed, at least Ag is contained as a metal component and the glass component is contained. A method of setting the baking temperature of this conductive paste based on the softening point of the crystallized glass and the melting point of Ag is disclosed while using a glass component containing crystallized glass. In this method, crystallized glass is used as the conductive paste, and the baking temperature is kept within a predetermined range to prevent the Ag of the conductive paste from diffusing into the internal electrodes.

Further, in Patent Document 5, Cu and Ag are contained as metal components as a conductive paste for forming an external electrode on the end side surface (end face) of the ceramic element body on which the internal electrode (including at least Pd) is exposed. A method is disclosed in which one or more types of crystallized glass are contained as a glass component, and as the crystallized glass, a glass having a softening point higher than the baking temperature of 50% or more is used. In this method, by using crystallized glass whose softening point is higher than the baking temperature as the main component of the conductive paste, the Ag of the conductive paste is suppressed from diffusing into the internal electrodes.

Japanese Unexamined Patent Publication No. 10-294239 Japanese Unexamined Patent Publication No. 2010-08703 Japanese Unexamined Patent Publication No. 2012-079862 Japanese Unexamined Patent Publication No. 2012-079862 Japanese Unexamined Patent Publication No. 2012-079862

However, none of the methods disclosed in Patent Documents 1 to 5 basically suppress the Kirkendal effect.

First, the method disclosed in Patent Documents 1 and 2 controls the protrusion of the internal electrode due to the Kirkendar effect by forming a glass layer. That is, these methods do not suppress the Kirkendal effect because they form an electrical connection between the internal electrode and the external electrode by utilizing the Kirkendal effect by forming a glass layer. Further, since these methods require a step of forming a glass layer using a special glass paste, the manufacturing cost cannot be suppressed and the manufacturing process also increases.

Further, in the method disclosed in Patent Documents 3 to 5, by using the crystallized glass as the conductive paste, the crystallized glass is conductive even if the baking temperature (baking temperature) exceeds the softening point of the crystallized glass. Utilizing its presence as a solid in the sex paste, it physically suppresses the diffusion of metals. That is, these methods do not suppress the Kirkendal effect because the protrusion of the internal electrodes is physically suppressed by inhibiting the contact between the metals by the solid crystallized glass. Further, in the method disclosed in Patent Document 3, since expensive Pd is used not only for the internal electrode but also for the external electrode, the manufacturing cost increases.

The present invention has been made to solve such a problem, and when forming an external electrode of a laminated chip component, a conductivity that suppresses the Kirkendar effect and realizes a good electrical connection with the internal electrode. The purpose is to provide a paste.

The conductive paste for forming an external electrode according to the present disclosure is provided in a main body made of ceramic in order to solve the above-mentioned problems, and the end face thereof is exposed on at least a part of the side surface of the main body. (A-1) silver powder and (A-2) metallic silicon powder as metal powder, (B) glass frit, and (B) glass frit, which are used to form an external electrode to be electrically connected. C) It contains an organic vehicle, and the weight ratio of the content of the (A-1) silver powder and the (A-2) metallic silicon powder is in the range of 99: 1 to 85:15. The volume ratio of the total amount of the metal powder (A) to the content of the glass frit (B) is in the range of 75:25 to 95: 5, and the softening point of the (B) glass frit is 450 ° C. to The configuration is within the range of 700 ° C.

According to the above configuration, the conductive paste contains not only (A-1) silver powder but also (A-2) metallic silicon powder as (A) metal powder, and these (A) metal powders. The weight ratio of the contents is set within a predetermined range, and the capacity cost of the contents of (A) metal powder and (B) glass frit is set within a predetermined range. Further, as the (B) glass frit, a glass frit whose softening point is lower than the firing temperature by about 50 ° C. is used.

As a result, when the conductive paste is fired to form an external electrode, the Kirkendal effect can be effectively suppressed, so that the contact surface (joint portion) with the external electrode and the internal electrode is prevented from protruding. At the same time, it is possible to suppress the formation of voids in the joint portion. Further, the quality of the external electrode itself can be improved. As a result, it is possible to obtain an external electrode that suppresses the Kirkendar effect and realizes a good electrical connection with the internal electrode.

In the conductive paste of the structure, (B) glass frit, its specific gravity may be within the range of ^{2.5g / cm 3 ~6.2g / cm 3} .

Further, the laminated chip component according to the present disclosure may have a configuration including an internal electrode containing palladium and an external electrode formed of the conductive paste having the above configuration.

Examples of the laminated chip component having the above configuration include a laminated ceramic capacitor, a laminated chip varistor, a laminated chip thermistor, and a laminated piezoelectric element.

According to the present invention, it is possible to provide a conductive paste that suppresses the Kirkendal effect and realizes a good electrical connection with the internal electrode when forming the external electrode of the laminated chip component by the above configuration. Play.

It is a schematic cross-sectional view which shows an example of the structure of the laminated ceramic element which is a typical example of the laminated chip component which concerns on this disclosure. (A) is a schematic cross-sectional view showing an example of the structure of a conventional laminated chip component (conventional laminated ceramic element), and (B) shows an example of a side surface portion of the laminated chip component shown in (A). It is a schematic partial cross-sectional view, and (C) is a schematic partial cross-sectional view which shows an example of the side surface part in the laminated chip part which concerns on this disclosure.

The conductive paste according to the present disclosure is provided on the side surface of a ceramic laminate formed by alternately laminating a plurality of ceramic layers and a plurality of internal electrodes, and is electrically applied to the end surface of the internal electrode exposed on the side surface. It is used to form an external electrode to be connected, that is, an external electrode of a laminated chip component. This conductive paste contains (A-1) silver powder and (A-2) metallic silicon powder as (A) metal powder (or (A) inorganic powder), (B) glass frit, and (C) organic. Contains vehicle. The weight ratio of the contents of (A-1) silver powder and (A-2) metal silicon powder is in the range of 99: 1 to 85:15, and (A) the total amount of metal powder and (B) glass. The volume ratio of the content with the frit is in the range of 75:25 to 95: 5, and preferably (B) the glass frit has a softening point in the range of 450 ° C. to 700 ° C. Hereinafter, typical embodiments of the present invention will be described.

[(A-1) Silver powder]
The specific composition of the (A-1) silver powder used in the conductive paste according to the present disclosure is not particularly limited, and a general silver powder (or silver particles or the like) used in a known conductive paste is preferably used. Can be used. As described above, the conductive paste according to the present disclosure is used for forming an external electrode of a laminated chip component, but a suitable configuration is suitable depending on the specific configuration of the laminated chip component, the specific configuration of the external electrode, and the like. Silver powder can be appropriately selected.

As a typical composition of the (A-1) silver powder, for example, one having an average particle size in the range of 0.3 μm to 20 μm, preferably in the range of 0.5 μm to 10 μm can be used. (A-1) If the average particle size of the silver powder is less than 0.3 μm, the viscosity of the paste tends to be high and the thixo property tends to be high, although it depends on the composition of the conductive paste. is there. If at least one of the viscosity and the thixophilicity of the conductive paste becomes relatively high, the handleability of the conductive paste during use may be affected.

Further, when the average particle size of the (A-1) silver powder exceeds 20 μm, an external electrode is formed, although it depends on the composition of the conductive paste, the specific composition of the laminated chip parts, the manufacturing conditions of the laminated chip parts, and the like. There is a possibility that the (A-1) silver powder may be insufficiently sintered during firing. When sintering is insufficient, not only the density of the obtained external electrode becomes low, but also the electrode surface becomes rough and voids are generated more often. As a result, a problem may occur when the external electrode is plated.

If the average particle size of the (A-1) silver powder is within the range of 0.5 μm to 10 μm, the handleability of the conductive paste can be improved and the handling property of the conductive paste can be improved at the time of firing, although it depends on various conditions. There is a tendency to achieve good sintering and form a suitable external electrode. The method for measuring the average particle size of (A-1) silver powder is not particularly limited, but in the present disclosure, a microtrack particle size distribution measuring device (Microtrack particle size distribution measuring device manufactured by Nikkiso Co., Ltd., trade name: 9320-). The average particle size D50 is measured and evaluated using HRA X-100).

In the silver powder (A-1), it is preferable that the BET specific surface area is within a predetermined range in addition to the above average particle size. Specifically, for example, BET specific surface area of (A-1) Silver powder may be within the range of 0.1~2m ² / g, there within the 0.3~1m ² / g More preferable. If the BET specific surface area of the (A-1) silver powder ^{is smaller than 0.1 m 2} / g, the contact area of the (A-1) silver powder becomes smaller, although it depends on various conditions, so that the (A-1) silver Since the contact probability between the powders or the internal electrodes decreases, the bonding between the electrodes deteriorates, which may affect the electrical characteristics.

On the other hand, if the BET specific surface area of ^{the (A-1) silver powder exceeds 2 m 2} / g, the contact area between the (A-1) silver powders increases, but the paste viscosity tends to increase, resulting in handleability. May affect. The method for measuring the BET specific surface area is not particularly limited, but in the present disclosure, it is measured and evaluated by the BET one-point method by nitrogen adsorption using a monosorb (manufactured by Quanta Chrome).

[(A-2) Metallic Silicon Powder]
The specific composition of the metallic silicon powder (A-2) used in the conductive paste according to the present disclosure is not particularly limited, but its purity is preferably 90% or more. The average particle size of the (A-2) metallic silicon powder is not particularly limited, but may be in the range of 0.3 μm to 20 μm, preferably 0.5 μm to the same as the (A-1) silver powder. Those within the range of 10 μm can be used.

If the average particle size of the (A-2) metallic silicon powder is less than 0.3 μm, the viscosity when formed into a paste will depend on the composition of the conductive paste, as in the case of the (A-1) silver powder. Tends to be high, and the viscosity tends to be high. If at least one of the viscosity and the thixophilicity of the conductive paste becomes relatively high, the handleability of the conductive paste during use may be affected.

On the other hand, when the average particle size of the (A-2) metallic silicon powder exceeds 20 μm, the average particle size of the (A-1) silver powder, the composition of the conductive paste, the manufacturing conditions of the laminated chip parts, etc. There is a possibility that the alloying of the (A-1) silver powder and the (A-2) metallic silicon powder does not proceed during firing for forming the external electrode. If the alloying does not proceed, the Kirkendal effect cannot be effectively suppressed when the conductive paste is fired, the internal electrode protrudes to the external electrode, and a gap is generated at the joint between the external electrode and the internal electrode. There is a possibility that it will happen.

(A-2) The metallic silicon powder alloys with silver below the temperature at which mutual diffusion of silver (Ag) and palladium (Pd) begins. As a result, metallic silicon (Si) and silver (Ag) are alloyed at a temperature below the temperature at which mutual diffusion between palladium (Pd) and silver (Ag) starts, so that the diffusion of silver is effectively inhibited and the Kirkendar effect is obtained. Can be satisfactorily suppressed. Further, since inexpensive metallic silicon (Ag) is used instead of expensive metal such as palladium (Pd), it is possible to effectively suppress an increase in the cost of the conductive paste.

[(B) Glass frit]
The specific configuration of the (B) glass frit used in the conductive paste according to the present disclosure is not particularly limited, and a glass frit known in the field of the baking type conductive paste can be preferably used. As described above, the conductive paste according to the present disclosure is used for forming an external electrode of a laminated chip component, but a suitable configuration is used depending on the specific configuration of the laminated chip component, the specific configuration of the external electrode, and the like. Glass frit can be appropriately selected.

As a typical configuration of the (B) glass frit, for example, a glass frit having a softening point in the range of 450 ° C. to 700 ° C. can be mentioned. In the present disclosure, the firing temperature (peak temperature) of the conductive paste for forming the external electrode is preferably in the range of 500 ° C. to 750 ° C., but in the present disclosure, the (B) glass frit is , It is preferable that the material is softened at a temperature lower than this firing temperature by about 50 ° C.

When the softening point of (B) glass frit exceeds 700 ° C., the softening point of (B) glass frit becomes too high, so that (A) metal powder ((A-1) silver powder and (A-2) metal silicon powder) ) Will be softened after the sintering of (B) has proceeded. As a result, (B) the glass frit stays in the conductor (inside the external electrode) and does not move to the interface between the laminated chip component and the external electrode. Therefore, good adhesion may not be achieved between the end side surface of the laminated chip component and the external electrode, and glass may seep out or poor plating may adhere to the surface of the external electrode. There is a risk (Comparative Example 6 described later).

If the softening point of the (B) glass frit is less than 450 ° C., the (B) glass frit may immediately soften and flow with low viscosity. As a result, the low-viscosity (B) glass frit flows before sintering the (A) metal powder ((A-1) silver powder and (A-2) metallic silicon powder), and (A). -1) It may interfere with the alloying of silver powder and (A-2) metallic silicon powder. As a result, the Kirkendar effect may not be effectively suppressed (Comparative Example 5 described later).

Further, it is generally known that glass frit having a low softening point has low acid resistance. Therefore, in the external electrode containing the glass frit at the low softening point, when the external electrode is plated, the glass frit is eroded by the acidic plating solution, and the glass frit is eroded between the end side surface of the laminated chip component and the external electrode. Good adhesion may not be achieved. As a result, good adhesion may not be achieved between the end side surface of the laminated chip component and the external electrode, or glass may seep out or plating may be poorly adhered to the surface of the external electrode ( Comparative example 6) described later.

(B) The glass frit is not particularly limited in properties other than the softening point, but a glass frit having a specific gravity within a predetermined range may be used. Specifically, for example, the specific gravity of the (B) glass frit may be in a range of ^{2.5g / cm 3 ~6.2g / cm 3} . When the specific gravity is within this range, better adhesion can be realized between the end side surface of the laminated chip component and the external electrode. The powder shape of other characteristics, for example, (B) glass frit, is not particularly limited, and may be a spherical powder or an irregularly shaped powder in which the shapes of the particles are not uniform. Further, the average particle size of (B) glass frit is not particularly limited, and may be any average particle size in the range known in the field of conductive paste.

(B) The specific type of the glass frit is not particularly limited, but for example, BiO _3- B ₂ O _3- SiO ₂ glass, ZnO-B ₂ O _3- SiO ₂ glass, R ₂ O-B ₂ O. _{Borosilicate glass such as 3-} SiO ₂ (where R is an alkali metal); _{boron-silicon carbide glass such as Bi 2} O _3- B ₂ O _3- SiC ₂ glass; etc. can be preferably used. .. Only one type of these (B) glass frit may be used, or two or more types may be appropriately combined and used.

[(C) Organic vehicle]
In the resistor paste composition according to the present invention, (C) an organic vehicle is blended in addition to (A-1) silver powder, (A-2) metallic silicon powder, and (B) glass frit.

(C) As the organic binder used in the organic vehicle, a resin known in the field of conductive paste can be preferably used. Specific organic binders include, for example, cellulose derivatives such as methyl cellulose, ethyl cellulose, hydroxyethyl cellulose, and cellulose nitrate; acrylic resins such as acrylic resin, methacrylic resin, acrylic acid ester polymer, and methacrylic acid ester polymer; polyvinyl butyral resin. Vinyl acetal resins such as, etc .; but are not particularly limited. Only one type of these organic binders may be used, or two or more types may be appropriately combined.

Further, the solvent used in (C) the organic vehicle can be used for adjusting physical properties such as viscosity or fluidity within a range that does not interfere with various physical properties of the conductive paste according to the present disclosure. The specific type of the solvent is not particularly limited, but for example, ketones such as methyl ethyl ketone, methyl isobutyl ketone and cyclohexanone; alcohols or glycol ethers such as terpineol, diethylene glycol monoethyl ether and diethylene glycol monobutyl ether and their acetate esters; acetic acid. Ester-based solvents such as butyl, amyl acetate, and γ-butyrolactone, aromatic solvents such as xylene and laurylbenzene; these solvents may be used alone or in combination of two or more.

(C) The organic vehicle may be a mixture of the above-mentioned organic binder and the above-mentioned solvent. Further, the mixing ratio of the organic binder and the solvent is not particularly limited.

[Conductive paste]
The method for producing the conductive paste according to the present disclosure is not particularly limited, and a method known in the field of conductive paste can be preferably used. As a typical example, there is a method in which each of the above-mentioned components is blended in a predetermined blending ratio and made into a paste using a known kneading device. Examples of the kneading device include known three-roll mills and the like, but the kneading device is not particularly limited. Moreover, each component may be premixed before kneading. Examples of the premixer include known planetary stirrers, but are not particularly limited.

Further, in the conductive paste according to the present disclosure, the above-mentioned (A) metal powder ((A-1) silver powder and (A-2) metal silicon powder), (B) glass frit, and (C) organic vehicle It suffices to contain each component of (D) and other components known in the field of conductive paste. Specific examples of the other component (D) include a dispersant, a stabilizer, an antioxidant, an ultraviolet absorber, an antifoaming agent, and a viscosity modifier.

Amount of (A) silver powder and (A-2) metallic silicon powder, (B) glass frit, and (C) organic vehicle, and (D) other components as required, which are metal powders. That is, the content (content rate) of the components (A) to (D) in the conductive paste according to the present disclosure is not particularly limited, but the content of the (A) metal powder is (A-1) silver powder. The weight ratio of the content of and (A-2) to the metallic silicon powder may be in the range of (A-1) :( A-2) = 99: 1 to 85:15. For convenience of explanation, the weight ratio of the contents of (A-1) silver powder and (A-2) metallic silicon powder is defined as "content condition 1".

If the content condition 1 deviates from the above range, the adhesion of the obtained external electrode to the laminated chip component may decrease, as shown in Examples described later. Further, if the content of the (A-1) silver powder in the (A) metal powder is too large, the Kirkendal effect is not effectively suppressed, and there is a possibility that the internal electrodes may protrude or voids may occur at the joint. Further, if the content of the (A-2) metallic silicon powder in the (A) metal powder is too large, there is a possibility that glass seepage or poor adhesion of plating may occur on the surface of the external electrode.

Further, in the conductive paste according to the present disclosure, in addition to the above-mentioned content condition 1, the total amount of (A) metal powder, that is, the total amount of (A-1) silver powder and (A-2) metal silicon powder (B) The condition that the volume ratio of the content with the glass frit is in the range of (A) :( B) = 75:25 to 95: 5 is satisfied. For convenience of explanation, the volume ratio of the content of (A) the total amount of the metal powder and (B) the glass frit is defined as "content condition 2".

Here, to explain the volume ratio under the content condition 2, the volume of each powder (referred to as the compounding volume for convenience) is calculated by dividing the compounding weight of each powder by the specific gravity, and the ratio of the compounding volume of each powder. Is the volume ratio of the content condition 2. Specifically, in the case of (A-1) silver powder, since the specific gravity (literature value) of silver is 10.5 g / cm ^3, it is blended (contained) in the conductive paste according to the present disclosure (A-1). -1) if the weight of the silver powder for example, W ^a-1 g, blending volume V ^a-1 of the (a-1) silver ^{powder, V a-1 [cm 3} ] = W a-1 [g ] ÷ 10.5 [g / cm ³ ].

Similarly, in the case of (A-2) metallic silicon powder, since the specific gravity (literature value) of metallic silicon is 2.33 g / cm ^3, it is blended (contained) in the conductive paste according to the present disclosure (A). -2) Assuming that the weight of the metallic silicon powder is, for example, WA ^-2 g, (A-2) the compounding capacity of the metallic silicon powder V ^A-2 is V ^A-2 [cm ³ ] = WA ^-2 [ It is calculated as g] ÷ 2.33 [g / cm ^3]. The specific densities of silver and metallic silicon are literature values described in "Chemical Encyclopedia" (Kyoritsu Shuppan Co., Ltd., 28th edition, 1984).

Since the specific gravity of (B) glass frit differs depending on the type of glass used as (B) glass frit, first, the true specific gravity of (B) glass frit is measured. In the present embodiment, the true specific gravity is measured by the Archimedes method from the obtained glass gob by melting about 5 g of glass frit at the softening point or higher. If the true specific gravity of the measured glass frit is, for example, S ^B g / cm ^3, and the weight of the (B) glass frit blended (contained) in the conductive paste according to the present disclosure is, for example, W ^B g, (B). ) blending capacity V ^B metal silicon powder of the glass frit is calculated as ^{V B [cm 3] = W} B [g] ÷ S B [g / mm 3].

Therefore, in the above-mentioned example, the volume ratio of the content of (A) total amount of metal powder ((A-1) total amount of silver powder and (A-2) metal silicon powder) and (B) glass frit is (A): (B) = V ^A-1 + V ^A-2 : V ^B.

When the content condition 2 deviates from the above range, the quality of the external electrode tends to deteriorate even if the Kirkendal effect can be suppressed, as shown in Examples described later. (A) If the total amount (volume) of the metal powder is too large, there is a risk that glass oozes out or plating adhesion is poor on the surface of the external electrode. Further, if (B) the content (volume) of the glass frit is too large, the adhesion of the external electrode to the laminated chip component may decrease.

The blending amount of (C) organic vehicle is not particularly limited. Generally, for example, the range of 0.05 to 30% by weight with respect to the entire conductive paste can be mentioned. Within this range, the handleability of the obtained conductive paste can be improved. Depending on the specific type of (A) metal powder and / or (B) glass frit constituting the conductive paste, or (C) the type of the organic vehicle itself, the blending amount is out of the above range ( C) Organic vehicles can be blended. Further, the blending amount of (D) and other components is not particularly limited, and may be blended within a range that does not interfere with the physical characteristics and functions of the conductive paste and the external electrode, and the action and effect of each component (A) to (C). ..

[Laminated chip parts]
The laminated chip component (or laminated electronic component) according to the present disclosure contains an external electrode formed by using the above-mentioned conductive paste according to the present disclosure, and is electrically connected to the external electrode and contains palladium (Pd). It suffices to include an internal electrode to be provided and a ceramic main body provided with the internal electrode.

The specific configuration of the ceramic body and internal electrodes is not particularly limited. The ceramic body may have a known shape or structure made of a ceramic material known in the field of laminated chip parts. Further, the internal electrode may be provided in a ceramic main body, contain palladium, and its end face may be exposed to at least a part of the side surface of the ceramic material. Therefore, the state in which the internal electrodes are exposed on the side surface of the main body is not particularly limited.

The conductive paste according to the present disclosure can be suitably used for forming an external electrode on the side surface of a ceramic body having such a structure. As described above, when the external electrode is generally formed of a conductive paste containing silver, the surface of the external electrode is formed as described above due to the mutual diffusion of silver and palladium during firing of the conductive paste. A phenomenon called "protrusion" occurs (Kerkendal effect), and the inside of the external electrode becomes empty. On the other hand, since the conductive paste according to the present disclosure can effectively suppress the Kirkendal effect as described above, it is possible to effectively suppress the occurrence of protrusion and / or depopulation at the external electrode.

As a typical laminated chip component, for example, a laminated ceramic element 10 having a configuration schematically shown in FIG. 1 can be mentioned. The laminated ceramic element 10 includes a ceramic element 11 (ceramic laminated body) and an external electrode 12. The ceramic body 11 has a plurality of ceramic layers 21 and a plurality of internal electrodes 22, and has a laminated structure in which the ceramic layers 21 and the internal electrodes 22 are alternately laminated. The ceramic layer 21 is made of a known ceramic, and the internal electrode 22 contains palladium.

The end faces of the internal electrodes 22 are exposed on both side surfaces of the ceramic body 11. Further, the external electrodes 12 are provided so as to cover both side surfaces of the ceramic body 11 and a part of the surface in the vicinity of the respective side surface surfaces. The external electrode 12 contains silver and is electrically connected to the internal electrode 22. Further, in the configuration shown in FIG. 1, a plating layer 23 of a known metal (for example, nickel (Ni), tin (Sn), etc.) is formed on the surface of the external electrode 12. The plating layer 23 functions as a terminal of the external electrode 12.

The method for manufacturing such a laminated ceramic element 10 is not particularly limited. Generally, a conductive paste layer serving as an internal electrode 22 is laminated between a plurality of ceramic green sheets, and the obtained laminate is heat-bonded and then processed into a predetermined shape and fired. By doing so, the ceramic element 11 can be manufactured. The external electrode 12 may be formed by applying the conductive paste according to the present disclosure to both side surfaces of the ceramic element 11 and firing it, and then the plating layer 23 may be formed. The method for forming the plating layer 23 is not particularly limited, and a known method can be used. For example, in the examples described later, the plating layer 23 is formed by using the barrel plating method.

When the laminated chip component according to the present disclosure is mounted on a wiring board or electrically connected to another electric element, the plating formed on the surface of the external electrode, that is, the external electrode terminal, and the wiring board or the electric element Electrically join the electrode terminals of the above with solder or the like. Therefore, in the external electrode, it is necessary that not only the internal electrical connection to the internal electrode but also the external electrical connection with the wiring board or other electric elements is good.

In the external electrode, the protrusion of the internal electrode or the void in the joint due to the Kirkendal effect affects the internal connection. On the other hand, depopulation of the external electrode itself, exudation of the glass component (derived from (B) glass frit), or poor adhesion of the plating (terminal) to the surface of the external electrode affects the external connection. The conductive paste according to the present disclosure can suppress the Kirkendal effect, suppress the depopulation of the external electrode, and effectively suppress the exudation of the glass component or the poor adhesion of the plating. As a result, the external electrode can be made even better than the conventional one, so that the laminated chip component provided with the external electrode can also be made good.

This point will be specifically described. For example, as schematically shown in FIG. 2 (A), the conventional laminated ceramic element 100 has basically the same configuration as the laminated ceramic element 10 according to the present disclosure shown in FIG. 1 (however, FIG. 2 (however, FIG. 2 (A)). In the configuration shown in A), the plating layer 23 is not formed). In this conventional laminated ceramic element 100, a conventional conductive paste is applied to a side surface of a ceramic body 11 having the above-described configuration and fired to form a conventional external electrode 112. The region S0 surrounded by a broken line in FIG. 2A is a portion of the conventional laminated ceramic element 100 in which the conventional external electrode 112 is formed on the side surface of the ceramic element 11.

FIG. 2B is a schematic partial cross-sectional view of region S0 in FIG. 2A. As shown in FIG. 2B, the edge of the internal electrode 22 is exposed on the side surface of the ceramic element 11, but when the conventional external electrode 112 is formed with the conventional conductive paste, the conventional conductivity is formed. When the sex paste is fired, it grows so as to project from the internal electrode 22 to the external electrode 112 due to the Kirkendal effect, and the projecting 22a is formed.

When the protrusion 22a grows toward the external electrode 112 with the firing of the conventional conductive paste, the contact surface between the internal electrode 22 and the external electrode 112 (or the interface, or the joint between the internal electrode 22 and the external electrode 112). In, a part of the external electrode 112 is pushed up. As a result, for example, as schematically shown in FIG. 2B, a cavity d0 (or a void) is formed around the protrusion 22a. If such a cavity d0 occurs, the external electrode 112 will be emptied.

On the other hand, in the laminated ceramic element 10 according to the present disclosure, as schematically shown in FIG. 2C, it is substantially avoided or suppressed that a protrusion 22a is generated at the edge 22b of the internal electrode 22. To. Therefore, the formation of the cavity d0 or the like in the external electrode 12 is effectively suppressed. This is because, as described above, the conductive paste according to the present disclosure used for the external electrode 12 has a weight ratio of the content of (A-1) silver powder and (A-2) metallic silicon powder, which is (A). -1): Content condition 1 that (A-2) = 99: 1 to 85:15, and (A) total amount of metal powder ((A-1) silver powder and (A-2)) The content condition 2 that the volume ratio of the content (total amount of metallic silicon powder) and (B) glass frit is in the range of (A) :( B) = 75: 25 to 95: 5 is satisfied. Because it is. In the conductive paste according to the present disclosure, (B) as long as it is within the range the specific gravity of the glass frit is ^{2.5g / cm 3 ~6.2g / cm 3} , to be more effectively suppressed Kakendaru effect Will also be possible.

The specific types and the like of the laminated chip parts according to the present disclosure are not particularly limited. Typical laminated chip components include a laminated ceramic capacitor, a laminated chip varistor, a laminated chip thermistor, a laminated piezoelectric element, and the like. Further, at least one internal electrode may be provided in a ceramic main body such as a ceramic laminate. Further, the end face of the internal electrode may be exposed at least a part of the side surface of the ceramic main body, and the external electrode may be electrically connected to the end face of the exposed internal electrode.

As described above, the conductive paste according to the present disclosure contains not only (A-1) silver powder but also (A-2) metallic silicon powder as (A) metal powder, and these (A) metals. The weight ratio of the powder content is set within a predetermined range, and the capacity cost of the contents of (A) metal powder and (B) glass frit is set within a predetermined range. Further, as the (B) glass frit, a glass frit whose softening point is lower than the firing temperature by about 50 ° C. is used.

As a result, when the conductive paste is fired to form an external electrode, the Kirkendal effect can be effectively suppressed, so that the contact surface (joint portion) with the external electrode and the internal electrode is prevented from protruding. At the same time, it is possible to suppress the formation of voids in the joint portion. Further, the quality of the external electrode itself can be improved. As a result, it is possible to obtain an external electrode that suppresses the Kirkendar effect and realizes a good electrical connection with the internal electrode.

The present invention will be described in more detail based on Examples and Comparative Examples, but the present invention is not limited thereto. Those skilled in the art can make various modifications, modifications, and modifications without departing from the scope of the present invention. The measurements and evaluations of various synthetic reactions and physical properties in the following examples were carried out as follows.

(Evaluation method)
[Evaluation of voids at the joint between the external electrode and the internal electrode]
By embedding the laminated chip parts with external electrodes obtained in Examples or Comparative Examples with an embedding resin (manufactured by BUEHLER, product name: EPOXI CURE (registered trademark)) and grinding with a grinder polisher. Polished. The shape of the cross section obtained by this polishing was observed with a scanning electron microscope (SEM, manufactured by Nippon Denshi Co., Ltd., product name: JSM-6510A). If there was, it was evaluated as "x", and if there was no void, it was evaluated as "○".

[Evaluation of protrusion of internal electrode to external electrode]
The laminated chip parts with external electrodes obtained in Examples or Comparative Examples are embedded and polished with an embedding resin in the same manner as in the void evaluation, and the cross-sectional shape obtained by this polishing is referred to as the void evaluation. Similarly, it was observed by SEM. If there was a protrusion of the internal electrode at the joint between the external electrode and the internal electrode, it was evaluated as “x”, and if there was no protrusion, it was evaluated as “◯”.

[Glass exudation or poor plating adhesion]
The surface of the laminated chip component with an external electrode obtained in Examples or Comparative Examples was observed by SEM. If there was glass bleeding or poor plating adhesion, it was evaluated as "x", otherwise it was evaluated as "○".

[Adhesion of external electrodes to elements]
Laminated chip parts with external electrodes obtained in Examples or Comparative Examples are soldered and mounted on a copper-clad printed circuit board according to JIS C5101, and a tensile compression tester (manufactured by Imada Seisakusho Co., Ltd., product name: SH-14ND-). 20RE) was applied by pressurizing 5N from the side surface. If there was no sign of peeling or peeling of the terminal electrode, it was evaluated as "○", and if a problem such as peeling or breakage occurred, it was evaluated as "x".

((A) metal powder, (B) glass frit, and (C) organic vehicle)
In Examples or Comparative Examples, the symbols A11 to A12 and A21 to A23 shown in Table 1 below were used as the (A-1) silver powder and the (A-2) metallic silicon powder, which are the metal powders. .. Further, as the (B) glass frit, those shown by reference numerals B1 to B6 shown in Table 2 below were used. Further, as the (C) organic vehicle, in both Examples and Comparative Examples, ethyl cellulose resin (manufactured by Dow Chemical Co., Ltd., product name: Etocell STD100) was used as terpineol / diethylene glycol monobutyl ether / diethylene glycol monobutyl ether = 5/3/2. The one dissolved in the mixed solvent was used. The mixing ratio of the ethyl cellulose resin and the above-mentioned mixed solvent was 92: 8.

(Example 1)
As a multilayer ceramic capacitor (MLCC, Multi-Layer Ceramic Capacitor) element before the external electrode was formed, an element having a size of 1608 (1.6 mm × 0.8 mm), a capacitance of 1 nF, and an internal electrode made of Pd was used. ..

The composition of (A) silver powder and (A-2) metallic silicon powder, (B) glass frit, and (C) organic vehicle, which are metal powders, shown in Table 3 (see Tables 1 and 2). After premixing with a planetary stirrer, kneading and dispersing with a three-roll mill to prepare (manufacture) the conductive paste according to Example 1.

Here, in the first embodiment, as shown in Table 3, the blending amount of the (A-1) silver powder is 70.2 parts by weight, and the blending amount of the (A-2) metallic silicon powder is 0.709 weight. It is a department. As the (B) glass frit, the glass frit B2 shown in Table 2 is used in an amount of 9.09 parts by weight. As described above, the specific density of silver (literature value) is 10.5 g / cm ³ , the specific gravity of metallic silicon (literature value) is 2.33 g / cm ³ , and the specific gravity of glass frit B2 (true specific density, measured value). ) Is 5.2 g / cm ³ (see Table 2).

Therefore, the volume ratio (A): (B) of the conductive paste according to the first embodiment is (70.2 ÷ 10.5) + (0.709 ÷ 2.33) :( 9.09 ÷ 5). .2) = 6.99: 1.75 = 80.0: 20.0 (see Table 3). The details of the calculation of the capacity ratio (A): (B) in Examples 2 to 11 and Comparative Examples 1 to 6 will be omitted.

The obtained conductive paste is dip-coated on the side surfaces of both ends of the MLCC element (the surface where the end faces of the internal electrodes made of Pd are exposed) by a dip coater, dried at 150 ° C. for 10 minutes, and then in a Box furnace. It was fired by heating. The heating and firing conditions were as follows: temperature rise: 20 ° C./min, peak temperature: 700 ° C. (see Table 3), and temperature reduction: natural cooling. As a result, external electrodes were formed on the side surfaces of both ends of the MLCC element.

The MLCC element with an external electrode thus obtained is subjected to electric field nickel plating using a barrel plating tester (manufactured by Yamamoto Plating Tester Co., Ltd., trade name: mini barrel 1-B type) to obtain an external electrode. A plating layer was formed on the surface. The conditions for forming the plating layer are a nickel anode plate (manufactured by Sumitomo Metal Mining Co., Ltd.) as an anode and a chrome-plated 2 mmφ ball as a cathode in a high pH, Watt bath, and 3 A / dm per cathode surface area. ^The condition was that the current of 2 was passed for 30 minutes. As a result, a laminated chip component with an external electrode according to Example 1 was obtained.

Regarding the obtained laminated chip component with an external electrode, as described above, the gap at the joint between the external electrode and the internal electrode, the protrusion of the internal electrode to the external electrode, the exudation of glass or the poor adhesion of plating, and the external electrode The adhesion to the element was evaluated. The results are shown in Table 3.

(Examples 2 to 4)
As shown in Table 3, the weight ratio of the contents of (A-1) silver powder and (A-2) metal silicon powder is changed, and the volume ratio of (A) metal powder and (B) glass frit is 80. The conductive pastes according to Examples 2 to 4 were prepared in the same manner as in Example 1 except that the ratio was adjusted to: 20, and laminated chip parts with external electrodes according to Examples 2 to 4 were obtained.

Regarding the obtained laminated chip component with an external electrode, as described above, the gap at the joint between the external electrode and the internal electrode, the protrusion of the internal electrode to the external electrode, the exudation of glass or the poor adhesion of plating, and the external electrode The adhesion to the element was evaluated. The results are shown in Table 3.

(Examples 5 to 8)
As shown in Table 3 or Table 4, the types of (A-1) silver powder and (A-2) metallic silicon powder are changed (see Table 1) to change the weight ratio of the contents, and (B). Conductivity according to Examples 5 to 8 in the same manner as in Example 1 except that the type of glass frit was changed (see Table 2) and the volume ratios of (A) metal powder and (B) glass frit were changed. Along with preparing the paste, laminated chip parts with external electrodes according to Examples 5 to 8 were obtained.

Regarding the obtained laminated chip component with an external electrode, as described above, the gap at the joint between the external electrode and the internal electrode, the protrusion of the internal electrode to the external electrode, the exudation of glass or the poor adhesion of plating, and the external electrode The adhesion to the element was evaluated. The results are shown in Table 3 or Table 4.

(Examples 9 to 11)
As shown in Table 4, the types of (A-1) silver powder and (A-2) metallic silicon powder were changed (see Table 1) to adjust the weight ratio of the contents to 90:10, and further. In Examples 9 to 11 in the same manner as in Example 1 except that (B) the type of the glass frit was changed (see Table 2), (A) the metal powder and (B) the volume ratio of the glass frit were changed. The conductive paste was prepared, and the laminated chip parts with external electrodes according to Examples 9 to 11 were obtained.

Regarding the obtained laminated chip component with an external electrode, as described above, the gap at the joint between the external electrode and the internal electrode, the protrusion of the internal electrode to the external electrode, the exudation of glass or the poor adhesion of plating, and the external electrode The adhesion to the element was evaluated. The results are shown in Table 4.

(Comparative Examples 1 to 6)
As shown in Table 5, whether the weight ratio of the contents of (A-1) silver powder and (A-2) metallic silicon powder is adjusted to be outside the range of 99: 1 to 85:15 (Comparative Example 1, Comparison). Example 2), the volume ratio of (A) metal powder and (B) glass frit is adjusted outside the range of 75:25 to 95: 5 (Comparative Example 3, Comparative Example 4), or (B) glass frit. The conductive pastes according to Comparative Examples 1 to 6 were prepared in the same manner as in Example 1 except that those having a softening point outside the range of 450 ° C. to 700 ° C. were used (Comparative Example 5 and Comparative Example 6). At the same time, laminated chip parts with external electrodes according to Comparative Examples 1 to 6 were obtained.

Regarding the obtained laminated chip component with an external electrode, as described above, the gap at the joint between the external electrode and the internal electrode, the protrusion of the internal electrode to the external electrode, the exudation of glass or the poor adhesion of plating, and the external electrode The adhesion to the element was evaluated. The results are shown in Table 5.

(Comparison between Examples and Comparative Examples)
As is clear from the results of Examples 1 to 11, the conductive paste according to the present disclosure is (A) a metal powder (A-1) silver powder and (A-2) a metal silicon powder, and (B). If the glass frit and (C) organic vehicle are contained, and in particular, (A) metal powder and (B) glass frit satisfy the above-mentioned content condition 1 and content condition 2, the Kirkendar effect is effectively suppressed. It is possible to form a good external electrode.

On the other hand, as is clear from the results of Comparative Examples 1 to 6, when the content condition 1 or the content condition 2 is not satisfied in the conductive paste, the Kirkendar effect cannot be effectively suppressed or the quality of the external electrode is poor. descend. Further, even if the content condition 1 and the content condition 2 are satisfied, if the softening point of the glass frit (B) is out of the predetermined range, the Kirkendar effect cannot be effectively suppressed, and the adhesion of the external electrode to the element is improved. Problems such as inadequacy or worsening of the wetting of the plating due to the exudation of glass to the surface of the external electrode occurred.

The present invention is not limited to the description of the above-described embodiment, and various modifications can be made within the scope of the claims, and the present invention is disclosed in different embodiments and a plurality of modifications. Embodiments obtained by appropriately combining the above technical means are also included in the technical scope of the present invention.

The present invention can be widely and suitably used in the field of laminated chip parts including external electrodes.

Claims (4)

It is provided inside a ceramic body and is used to form an external electrode that electrically connects to an internal electrode whose end face is exposed on at least a portion of the side surface of the body.
It contains (A) silver powder and (A-2) metallic silicon powder as metal powder, (B) glass frit, and (C) organic vehicle.
The weight ratio of the contents of the (A-1) silver powder and the (A-2) metallic silicon powder is in the range of 99: 1 to 85:15.
The volume ratio of the total amount of the (A) metal powder to the content of the (B) glass frit is in the range of 75:25 to 95: 5.
The glass frit (B) is characterized in that its softening point is in the range of 450 ° C. to 700 ° C.
Conductive paste for forming external electrodes. (B) the glass frit is characterized in that its specific gravity is in the range of ^{2.5g / cm 3 ~6.2g / cm 3} ,
The conductive paste according to claim 1. With an internal electrode containing palladium,
An external electrode formed of the conductive paste according to claim 1 or 2 is provided.
Laminated chip parts. It is a multilayer ceramic capacitor, a multilayer chip varistor, a multilayer chip thermistor, or a multilayer piezoelectric element.
The laminated chip component according to claim 3.

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