KR101807876B1 - Conductive paste for external electrode, and laminated ceramic electronic component having the external electrode formed using the same - Google Patents

Abstract

The present invention provides a conductive paste for an external electrode in which an external electrode having a low bending elastic modulus and excellent in stress relaxation is obtained, and a multilayer ceramic electronic device using the same.
The present invention provides a conductive paste for an external electrode for forming a second conductor layer of an external electrode having a first conductor layer connected to an internal electrode and a second conductor layer laminated on the first conductor layer, (B) a thermosetting resin, (C) a rubber particle selected from the group consisting of silicone rubber particles and fluorine rubber particles, wherein at least 70% by weight of the total thermosetting resin as the component (B) has an epoxy equivalent of 200 to 1500 Of a bifunctional epoxy resin. Further, the multilayer ceramic electronic component is provided with the external electrode.

Description

TECHNICAL FIELD [0001] The present invention relates to a multilayer ceramic electronic device having a conductive paste for an external electrode and an external electrode formed using the conductive paste.

The present invention relates to a conductive paste for an external electrode for forming a second conductor layer of an external electrode having a first conductor layer connected to an internal electrode and a second conductor layer laminated on the first conductor layer, A second conductor layer, and an external electrode including a first conductor layer.

A conventional multilayer ceramic electronic component will be described by taking the multilayer ceramic capacitor shown in Fig. 1 as an example. The multilayer ceramic capacitor 1 has a structure in which an external electrode layer 4 is provided on an internal electrode lead-out surface of a ceramic composite body in which ceramic dielectric 2 and internal electrode layer 3 are alternately laminated. Typically, the external electrode has a structure in which the plated layer 5 is formed on the external electrode layer 4. [ The plating treatment layer 5 is typically composed of a nickel plating layer and a tin plating layer.

When the multilayer ceramic capacitor is mounted on the circuit board 7, the external electrodes of the multilayer ceramic capacitor and the wiring electrodes of the circuit board are connected by soldering. Due to this structure, if an external force is applied to the circuit board on which the multilayer ceramic capacitor is mounted, or if the circuit board is bent, stress is transmitted to the multilayer ceramic capacitor through the brazing layer 6. This stress may cause the external electrode and the ceramic composite to peel off or cracks to occur in the ceramic composite, which may cause failure of the electronic device. Therefore, development of an external electrode having excellent stress relaxation has been a problem.

A method for relieving stress applied to an external electrode includes the steps of laminating a second conductor layer (12) containing a resin as a buffer material on a first conductor layer (11) of an external electrode connected to an internal electrode of a multilayer capacitor (Refer to Fig. 2) constituting an external electrode made of a layer of a metal (for example, see Patent Document 1). This technique absorbs the stress applied to the external electrode by the second conductor layer including the flexible resin, thereby relieving stress on the external electrode. In applications where vibration or impact is applied, further improvement is required do.

There has been proposed a conductive paste in which an epoxy resin is blended with metal particles as a conductive paste for forming a second conductor layer including a resin for stress relaxation which is laminated on a first conductor layer connected to an internal electrode , Patent Documents 2 to 4). However, since the epoxy resin has a high modulus of elasticity, there is a problem in relieving the stress when an external force is applied to the circuit board.

Japanese Patent Application Laid-Open No. 5-144665 Japanese Patent Application Laid-Open No. 11-162771 Japanese Patent Application Laid-Open No. 11-219849 Japanese Patent Application Laid-Open No. 2002-246258

The inventors of the present invention have made various investigations in order to solve the above problems and found that by using a specific conductive paste as a conductive paste for forming a second conductor layer laminated on a first conductor layer connected to an internal electrode, It is possible to obtain an external electrode excellent in relaxation and to prevent peeling of the external electrode and the ceramic composite body or occurrence of cracks in the ceramic composite body even when stress is applied, thereby completing the present invention.

The present invention provides a conductive paste for an external electrode for forming a second conductor layer of an external electrode having a first conductor layer connected to an internal electrode and a second conductor layer laminated on the first conductor layer, (B) a thermosetting resin, (C) a rubber particle selected from the group consisting of silicone rubber particles and fluorine rubber particles, wherein at least 70% by weight of the total thermosetting resin as the component (B) has an epoxy equivalent of 200 to 1500 Of a bifunctional epoxy resin for an external electrode.

By using the conductive paste for the external electrode of the present invention as the conductive paste for the second conductor layer and by laminating the second conductor layer including the resin on the first conductor layer connected to the internal electrode to form the external electrode, And an external electrode excellent in the relaxation of stress can be obtained, so that even when stress is applied, it is possible to prevent the external electrode and the ceramic composite body from peeling off or causing cracks to occur in the ceramic composite body. In addition, the external electrode having the second conductor layer formed by using the conductive paste for the external electrode of the present invention maintains the bending elastic modulus with time, and can maintain a state excellent in relaxation of the stress. The multilayer ceramic electronic component having high reliability can be obtained by forming the second conductor layer using the conductive paste for the external electrode of the present invention and having the first conductor layer and the second conductor layer with the external electrode.

1 is a schematic diagram showing the structure of a conventional multilayer ceramic capacitor.
Fig. 2 is a schematic diagram showing the structure of a ceramic capacitor having an outer electrode composed of a plurality of conductor layers, in which a second conductor layer including a resin is laminated on a first conductor layer connected to an inner electrode.

In the present invention, the term " first conductor layer " refers to a conductor layer constituting an external electrode, and refers to a conductor layer directly connected to the internal electrode. The " second conductor layer " refers to a conductor layer constituting an external electrode, and refers to a conductor layer laminated on the first conductor layer.

The conductive paste for external electrodes of the present invention comprises rubber particles selected from the group consisting of (A) metal particles, (B) a thermosetting resin, (C) silicone rubber particles and fluorine rubber particles, At least 70% by weight of the entire thermosetting resin is a bifunctional epoxy resin having an epoxy equivalent of 200 to 1500. Hereinafter, the components (A) to (C) will be described in detail.

(A) metal particles

The metal particles are components for imparting conductivity to the external electrode and have a melting point of 700 캜 or higher. The melting point of the metal particles is preferably 800 DEG C or higher. The upper limit of the melting point is not particularly limited, but is usually 1800 占 폚 or lower and preferably 1600 占 폚 or lower. The metal particles may be used alone or in combination of two or more.

Examples of the metal particles include metal particles of Ag, Cu, Ni, Pd, Au and Pt. And metal particles of Ag are preferable in that excellent conductivity is relatively easily obtained.

Further, alloys of Ag, Cu, Ni, Pd, Au and Pt can be enumerated. Of these, metal particles having a melting point of 700 ° C or higher are preferable. Particles of an Ag alloy are preferable in that excellent conductivity can be obtained relatively easily.

Examples of the particles of the alloy include metal particles of an alloy composed of two or more elements selected from the group consisting of Ag, Cu, Ni, Pd, Au and Pt. Examples of binary Ag alloys include AgCu alloy, AgAu alloy , An AgPd alloy, and an AgNi alloy. Examples of the ternary Ag alloy include an AgPdCu alloy and an AgCuNi alloy.

Examples of the particles of the alloy include metal particles of an alloy composed of at least one element selected from the group consisting of Ag, Cu, Ni, Pd, Au and Pt and at least one other element. Among them, Lt; 0 > C or more is preferable. As other elements, Zn, Al and Sn can be mentioned. In the case of a binary alloy of Sn and Ag, an AgSn alloy having a weight ratio of Sn to Ag of more than 25.5: 74.5 can be used.

As the metal particles, metal particles having a melting point of Sn, In, and Bi having a melting point of from 200 캜 to less than 700 캜 may be used. The low-melting-point metal particles are preferably non-Pb.

As the metal particles having a low melting point, metal particles of an alloy having a melting point of at least 200 캜 and less than 700 캜 may be used as an alloy of Sn, In, and Bi. A Sn alloy is preferable in that excellent conductivity is relatively easily obtained. Examples of the particles of the alloy include metal particles of an alloy composed of two or more elements selected from the group consisting of Sn, In and Bi, and examples of the binary alloy include SnIn alloy.

The shape of the metal particles may be any shape such as spherical, flake, scaly, or needle-like. The average particle diameter of these is preferably from 0.015 to 30 탆 in that the surface state after printing or coating is good and excellent conductivity can be imparted to the formed electrode layer. When the metal particles are spherical, the average particle diameter is more preferably in the range of 0.2 to 5 mu m. When the metal particles are flake-type, the average particle size is more preferably in the range of 5 to 30 mu m. In the present specification, the average particle diameter refers to an average of particle diameters in the case of a spherical shape, a diameter of the longest part in the case of a flake type, a long diameter of a particle flake in the case of a scaly shape, and a length in the case of an acicular shape. Here, the average particle diameter of the metal particles is measured by a scanning electron microscope (SEM) and is determined by image analysis.

The metal particles are preferably used in combination of (A1) spherical silver particles and (A2) flake silver particles. The silver particles of (A1) and (A2) are preferably in a weight ratio of 10:90 to 90:10. By setting the ratio of the spherical silver powder and the flake silver powder within the above-mentioned range, it is preferable not only to lower the resistivity value but also to improve the coating shape and plating adhesion. More preferably, it is from 20:80 to 80:20, and more preferably from 40:60 to 60:40. The ratio of (A1) to (A2) may be 30:70 to 70:30. The metal particles used in the present invention may be those commercially available or those produced by methods known to those skilled in the art.

(B) Thermosetting resin

The thermosetting resin functions as a binder. The thermosetting resin used in the present invention may be used in combination with a plurality of thermosetting resins, but at least 70% by weight based on the weight of the whole thermosetting resin is a bifunctional epoxy resin having an epoxy equivalent of 200 to 1500. Here, " epoxy equivalent " refers to a value obtained by dividing the molecular weight of the resin by the number of epoxy groups in the molecule. By setting the epoxy equivalent to this range, not only the bendability of the external electrode but also the resistivity value can be suppressed to be small. The range of the epoxy equivalent is preferably 350 to 1200, more preferably 500 to 850. Examples of preferred bifunctional epoxy resins include bisphenol A type epoxy resins and bisphenol F type epoxy resins.

Examples of the thermosetting resin that can be used in combination with the bifunctional epoxy resin having an epoxy equivalent of 200 to 1500 include amino resins such as urea resin, melamine resin and guanamine resin; Oxetane resin; Phenol resins such as resol type, alkyl resol type, novolac type, alkyl novolac type, and aralkyl novolac type; Silicone-modified organic resins such as silicone epoxy and silicone polyester, bismaleimide, and polyimide resin. For example, a BT resin can be used. An epoxy resin having an epoxy equivalent of 200 to 1,500 may also be used. These resins may be used alone or in combination of two or more.

Use of a thermosetting resin that is liquid at room temperature as the thermosetting resin is preferable because the amount of the organic solvent used as the diluting agent can be reduced. Examples of such liquid phase thermosetting resins include liquid epoxy resins, liquid phenolic resins, and the like. Further, it is also possible to further add and mix resins having compatibility with these liquid resins and exhibiting a solid to ultra high viscosity at room temperature within a range in which the mixing system exhibits fluidity. As such a resin, an epoxy resin such as a high molecular weight bisphenol A type epoxy resin, diglycidylbiphenyl, novolak type epoxy resin, tetrabromobisphenol A type epoxy resin; Resole-type phenol resins, novolac-type phenol resins, and aralkyl novolac-type phenol resins.

(C) a rubber particle selected from the group consisting of silicone rubber particles and fluorine rubber particles

The rubber particles selected from the group consisting of silicone rubber particles and fluorine rubber particles lower the flexural modulus of the external electrode and contribute to the stress relaxation of the external electrode. These rubber particles are excellent in heat resistance and suppress deterioration due to heat at the time of forming the second conductor layer. These may be used alone or in combination of two or more.

Examples of the silicone rubber particles include particles obtained by three-dimensionally crosslinking a linear organopolysiloxane (JP 63-77942 A), particles obtained by powdering a silicone rubber (JP 62-270660 A Etc.). There is also a particle having a structure in which the surface of the above-mentioned particles is covered with a silicone resin (JP-A-7-196815, etc.).

Examples of the silicone rubber particles include Trampol E-500, Trampol E-600, Trampol E-601 and Trampol E-850 (both manufactured by Toray Dow Corning Silicone), KMP-600, KMP-601 and KMP-602 , And KMP-605 (all manufactured by Shin-Etsu Chemical Co., Ltd.).

Examples of the fluorine rubber particles include binary copolymers of vinylidene fluoride and hexafluoropropylene, binary copolymers of vinylidene fluoride and pentafluoropropylene, binary copolymers of vinylidene fluoride and chlorotrifluoroethylene, Ternary copolymers of vinylidene fluoride, hexafluoropropylene and tetrafluoroethylene, terpolymers of vinylidene fluoride and pentafluoropropylene and tetrafluoroethylene, vinylidene fluoride and perfluoromethylvinyl Tertiary copolymers of ether and tetrafluoroethylene, and the like.

The shape of the rubber particles is preferably spherical. The average particle diameter of the rubber particles is preferably 0.01 to 30 占 퐉, more preferably 1 to 6 占 퐉, from the viewpoint of obtaining a favorable bending elastic modulus. In the present specification, the average particle diameter of the rubber particles is a value obtained by observing with a scanning electron microscope (SEM) and analyzing images.

It is preferable that the total amount of the component (B) and the component (C) is 10 to 45 parts by weight based on 100 parts by weight of the metal particles (A) in terms of lowering the bending modulus of elasticity of the external electrode . More preferably 15 to 35 parts by weight, still more preferably 25 to 35 parts by weight. The weight ratio of (A) to (B) + (C) is preferably within the above-mentioned range because the resistivity value can be suppressed as well as the coating shape and plating adhesion can be improved.

(B) :( C) of the rubber particles selected from the group consisting of (B) the thermosetting resin and (C) the silicone rubber particles and the fluorine rubber particles is preferably 90:10 to 45:55, more preferably It is from 85:15 to 70:30.

In the conductive paste for external electrodes of the present invention, as the curing mechanism of the bifunctional epoxy resin having an epoxy equivalent of 200 to 1500 in the component (B), even if a self-curing resin is used, a curing agent such as amines, imidazoles, acid anhydrides or onium salts The same hardening agent or hardening catalyst may be used, or the amino resin or phenol resin may be made to function as a hardening agent for the epoxy resin.

Especially, an epoxy resin which is cured by a phenol resin is preferable. The phenol resin may be an early condensation product of a phenol resin which is usually used as a curing agent for an epoxy resin, and may be a resol type or a novolac type. In order to obtain excellent heat cycle resistance, at least 50% A phenol resin, a phenol resin, an aralkyl novolak type phenol resin, a xylene resin, or an allyl phenol resin. An aralkyl novolak type phenol resin represented by the following formula (3), which is a polycondensation product of phenol / p-xylylene glycol dimethyl ether, is also preferable. Further, in the case of an alkylresol-type phenol resin, an average molecular weight of 2,000 or more is preferable in order to obtain excellent printability. In the alkylol solvolol type or alkyl novolac type phenolic resin, those having 1 to 18 carbon atoms can be used as the alkyl group and those having 2 to 10 carbon atoms such as ethyl, propyl, butyl, pentyl, hexyl, octyl, desirable.

(3)

(Wherein n is 0 to 300)

Of these, a combination of an epoxy resin and an aralkyl novolac phenolic resin, a resol-type phenol resin, a xylene resin, or an allyl phenolic resin is preferable in view of excellent adhesion and excellent heat resistance. When a combination of an epoxy resin and an aralkyl novolak type phenol resin, a resol type phenol resin, a xylene resin or an allyl phenol resin is used, the weight ratio of the epoxy resin to the phenol resin is preferably in the range of 4: 1 to 1: 4 , And still more preferably from 4: 1 to 1: 2. Polyimide resins and the like are also effective in terms of heat resistance.

The paste of the present invention may contain, in addition to the components (A) to (C), imidazoles such as 2-phenyl-4-methyl-5-hydroxymethylimidazole, , A curing catalyst such as dicyandiamide, a coupling agent, a thixotropic agent and a dispersing agent. In addition to the thermosetting resin, a thermoplastic resin may also be used. As the thermoplastic resin, polysulfone, polyethersulfone, maleimide resin and the like are preferable.

The paste of the present invention can be blended with an organic solvent to adjust the viscosity. Examples of the organic solvent include aromatic hydrocarbons such as toluene, xylene, mesitylene and tetralin; Ethers such as tetrahydrofuran; Ketones such as methyl ethyl ketone, methyl isobutyl ketone, cyclohexanone, and isophorone; Lactones such as 2-pyrrolidone and 1-methyl-2-pyrrolidone; Ethers such as ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monobutyl ether, and corresponding propylene glycol derivatives Alcohols; Esters such as acetic acid esters corresponding thereto; And diesters such as methyl esters and ethyl esters of dicarboxylic acids such as malonic acid and succinic acid. The amount of the organic solvent to be used is arbitrarily selected depending on the method of printing or applying the paste. For example, in the case of screen printing, the external viscosity of the paste at room temperature is preferably from 10 to 500 Pa · s, 300 Pa · s.

In the paste of the present invention, known additives may be added, if necessary. For example, as the dispersion aid, an aluminum chelate compound such as diisopropoxy (ethylacetate) aluminum; Titanate esters such as isopropyl triisostearoyl titanate; Aliphatic polycarboxylic acid esters; Unsaturated fatty acid amine salts; Surfactants such as sorbitan monooleate; Or a polymer compound such as a polyester amine salt or a polyamide. Inorganic and organic pigments, silane coupling agents, leveling agents, thixotropic agents, antifoaming agents and the like may also be added.

The paste of the present invention can be produced by uniformly mixing the compounding ingredients by a mixing means such as a pulverizer, a propeller stirrer, a kneader, a roll, a pot mill or the like. The production temperature is not particularly limited, but can be, for example, 10 to 40 占 폚.

By using the paste of the present invention, the second conductor layer is formed on the first conductor layer connected to the internal electrode layer of the multilayer ceramic electronic component, so that the external electrode composed of a plurality of layers can be formed. The method of formation is not particularly limited, and a known method can be used. For example, the paste of the present invention may be printed or coated on the first conductor layer of the external electrode of the multilayer ceramic electronic component, and if necessary, dried and then cured by heating to form the second conductor layer.

The first conductor layer connected to the internal electrode layer can be obtained by, for example, applying an electrode paste containing glass frit to the internal electrode lead-out surface of the multilayer ceramic composite body by using, for example, silver as a main component, . As a method of printing, applying, drying and firing the electrode paste, a method known to a person skilled in the art can be used.

The coating thickness in the printing / coating process is usually 10 to 200 占 퐉, preferably 20 to 100 占 퐉. The drying process is performed mainly in the case of using an organic solvent, and can be performed at room temperature or by heating (for example, heating at 80 to 160 캜). The curing process can be usually carried out at 150 to 250 ° C. The curing temperature is preferably 150 占 폚 or higher, and more preferably 180 占 폚 or higher. Further, it is preferably 250 占 폚 or lower, and more preferably 220 占 폚 or lower, in order to exclude the adverse effect of heat on the rubber particles selected from the group consisting of (C) the silicone rubber particles and the fluorine rubber particles.

The curing time may vary depending on the curing temperature and the like, but is preferably 1 to 60 minutes in view of workability. For example, when the resin in the paste is an epoxy resin using a phenol resin as a curing agent, the second conductor layer constituting the external electrode can be formed by performing the curing at 150 to 250 DEG C for 10 to 60 minutes.

The multilayer ceramic electronic component having the first conductor layer and the external electrode having the second conductor layer formed using the paste of the present invention can suppress the capacity drop after the bending test to 10% or less. The bending test may be, for example, 90 mm In the two-point support, the central portion is pressed at a displacement speed of 1 mm / sec to warp the substrate by 10 mm.

A plating process such as nickel plating, tin plating, or the like can be carried out if necessary in order to further increase the bonding strength of the external electrode formed in this way when soldered to a circuit board or the like.

Examples of the multilayer ceramic electronic component in which the external electrode is formed include a capacitor, a capacitor array, a thermistor, a varistor, an inductor, and LC, CR, LR and LCR composite components.

[Example]

Hereinafter, the present invention will be described in more detail with reference to Examples and Comparative Examples. But the present invention is not limited to these examples.

[Preparation of conductive paste]

The components shown in Table 1 were mixed to prepare conductive pastes of Examples and Comparative Examples (the numbers in the tables are parts by weight unless otherwise specified).

The components used in Examples and Comparative Examples are as follows. The epoxy resin used was an epoxy resin 1 to 4, and bisphenol A type epoxy resins having epoxy equivalents of 190, 670, 940 and 2500, respectively. As the phenol resin, a novolac phenolic resin having a hydroxyl equivalent of 110 was used. As silicone rubber particles, silicone rubber (trade name: KMP600, KMP605, KMP601, manufactured by Shin-Etsu Silicone Co., Ltd.) having an average particle diameter of 2, 5 and 12 탆 was used as spherical silicone rubber particles 1 to 3. As the liquid rubber, a carboxyl group-terminated acrylonitrile butadiene rubber was used. As the catalyst, dicyandiamide was used. As the epoxy silane coupling agent, 3-glycidoxypropyltrimethoxysilane was used. In each of Examples and Comparative Examples, an adjusted amount of butyl carbitol as a solvent was added to the metal paste. At that time, the amount of the solvent was adjusted so that the viscosity of the paste was in the range of 32 to 38 Pa · s. The viscosity was measured at room temperature using a Brookfield DV-1 type viscometer at 10 rpm.

The resistivity, adhesion strength, and flexural modulus of the second conductor layer formed using the conductive paste of Examples and Comparative Examples were measured as follows. Further, a bending test was conducted by the following method. The results are shown in Table 1.

[Measurement of resistivity]

On the alumina substrate having a width of 20 mm, a length of 20 mm and a thickness of 1 mm, a 250 mesh stainless steel screen was used for the electroconductive paste of Examples and Comparative Examples to prepare a zigzag having a length of 71 mm, a width of 1 mm, Pattern printing was performed, and curing was performed at 200 캜 for 30 minutes in the air to form an external electrode. The thickness of the zigzag pattern was obtained from the average of six points measured so as to cross the pattern with a surface roughness shape measuring instrument (trade name: Surfcom 1400, manufactured by Tokyo Seimitsu Co., Ltd.). After curing, the resistivity was measured by a four-terminal method using an LCR meter.

[Measurement of adhesion strength]

The paste of the comparative example and the example was screen printed on an alumina substrate of 20 mm ² by screen printing, and the alumina chip of 1.5 × 3.0 mm was placed thereon and cured at 200 ° C. for 30 minutes. Thereafter, the adhesive surface was pushed from the side with a push-pull gauge, and the numerical value at the time when the alumina chip was peeled was read. The calculation formula is as follows.

Adhesive strength = measured value (Kgf) x 9.8 / 0.03 (cm ² )

[Measurement of flexural modulus of elasticity]

The paste of the comparative example and the example was applied to a Teflon plate with a thickness of 2 heat-resistant tapes and cured at 200 캜 for 30 minutes. After curing, the test piece was peeled from the Teflon plate and annealed at 150 ° C for 10 minutes. The test piece was extracted from the cured film obtained at 1 cm x 4 cm, and used as a sample for bending test. The test pieces were aged at 150 ° C for 0, 20, 100, and 1000 hours. Each test piece was measured for bending elastic modulus with an autograph of Shimadzu Science.

[Bending test]

A Cu electrode (first conductor layer connected to the internal electrode) was prepared on the internal electrode lead-out surface of the ceramic composite body (1608 type) of the chip stacked capacitor. The paste of the comparative example and the example was uniformly dipped in a Paloma printing machine (model number: MODEL 2001) manufactured by esi, and then cured at 200 ° C for 30 minutes to form an external electrode as a second conductor layer. Subsequently, nickel plating was performed in a watt bath, and then tin plating was performed by electrolytic plating to obtain a chip-laminated capacitor. Next, a solder paste having a composition of Sn-3.0Ag-0.5Cu was printed on the FR-4 substrate, and the multilayer ceramic capacitor was mounted. After that, the reflow process was performed under the conditions of the in-out of 5 minutes and the peak temperature of 260 ° C A test piece for evaluation was prepared. The test specimen for evaluation was measured with an autograph (manufactured by Shimadzu Corporation) In the two-point support, the center portion was pressed with a jig of R 230 mm from the FR-4 substrate side at a displacement speed of 1 mm / sec to check whether the substrate was warped by 10 mm or not. In the capacity determination, the case where the initial capacity was lowered by 10% or more was regarded as inexecutable (X).

The conductor layers prepared in Examples 1 to 3 were observed for their surface shape, plating adhesion and coating shape. Each observation and evaluation method is as follows.

[Surface shape]

SEM observation was conducted at 500 times the end of the electrode surface using the test piece used for measuring the specific resistance value. When the number of observed particles of 10 mu m or more was less than 5, it was made good.

[Plating adhesion]

A chip-laminated capacitor was obtained in the same manner as in the bending test. The surface of the obtained capacitor was observed by SEM at 500 times. And that the external electrode is plated.

[Application form]

A Cu electrode (first conductor layer connected to the internal electrode) was prepared on the internal electrode lead-out surface of the ceramic composite body (1608 type) of the chip stacked capacitor. The paste of the comparative example and the example was uniformly dipped in a Paloma printing machine (model number: MODEL 2001) manufactured by esi, and then cured at 200 ° C for 30 minutes to form a second conductor layer containing resin to form an external electrode Respectively. The resultant chip-laminated capacitor was observed with a microscope 20 times and the surface of the external electrode was observed. The flat surface was rated good.

As shown in Examples 1 to 8, when the conductive paste of the present invention is used, good bond strength and bending elastic modulus can be realized at the same time while maintaining good electrical characteristics. After the bending test, No destruction was found. On the other hand, in Comparative Example 1 not containing the component (C), the bending elastic modulus was as large as 10.1, and the ceramic composite was cracked by the bending test. In Comparative Example 2 using an epoxy resin having an epoxy equivalent of less than 200, the bending elastic modulus was 9.0, and fracture occurred during the bending test. In Comparative Example 3 using an epoxy resin having an epoxy equivalent of more than 1,500, the resistivity value was as large as 7.3, and was deteriorated in terms of electrical characteristics. In Comparative Example 4 using the liquid rubber instead of the rubber particles of the component (C), the bending elastic modulus was increased by aging and fracture was caused by the bending test. In addition, the second conductor layer containing the resin prepared in Examples 1 to 3 was satisfactory in terms of the printed surface, the coating shape, and the plating adhesion.

1: Multilayer Ceramic Capacitor
2: Ceramic dielectric
3: internal electrode layer
4: external electrode layer
5: Plated layer
6: Solder layer
7: substrate
11: a first conductor layer connected to the internal electrode
12: second conductor layer containing resin

Claims (7)

1. A conductive paste for an external electrode for forming a second conductor layer of an external electrode having a first conductor layer connected to an internal electrode and a second conductor layer laminated on the first conductor layer,
(A) metal particles,
(B) a thermosetting resin,
(B) at least 70% by weight of the total thermosetting resin is an epoxy equivalent of 200 to 1,500, and (A) at least one epoxy resin selected from the group consisting of ) The total amount of the component (B) and the component (C) is 10 to 45 parts by weight based on 100 parts by weight of the metal particles. The conductive paste for external electrodes according to claim 1, wherein the component (C) has an average particle diameter of 1 to 6 탆. The conductive paste for external electrodes according to claim 1, wherein component (A) is silver particles. The conductive paste for external electrodes according to claim 1, wherein the component (A) is spherical silver particles and the flake type is particles, and the spherical silver particles and flake type silver particles are in a ratio of 30:70 to 70:30. The conductive paste for external electrodes according to claim 1, wherein the total amount of the component (B) and the component (C) is from 15 to 35 parts by weight based on 100 parts by weight of the component (A). An outer electrode having a first conductor layer connected to the inner electrode and a second conductor layer formed by using the conductive paste for an outer electrode according to any one of claims 1 to 5 laminated on the first conductor layer, Comprising: a laminated ceramic electronic component. 7. The method of claim 6, Wherein the rate of capacity decrease after the bending test in which the center portion is pressed at a displacement speed of 1 mm / sec and the substrate is bent by 10 mm in the two-point support is 10% or less.

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