External electrode paste

Abstract

Provided is an external electrode paste capable of improving the strength and moisture resistance reliability of a dry film. This external electrode paste which is used for forming an external electrode of a multilayer ceramic electronic component comprises: an acrylic resin and an ethyl cellulose-based resin which are at least partially copolymerized; a Cu powder; a glass powder; and a solvent. For D50_Cu of the Cu powder and D50_Glass of the glass powder obtained by a laser diffraction scattering-type particle size distribution measurement method, the ratio (D50_Glass / D50_Cu) of D50_Glass to D50_Cu is 0.13-0.67, D50_Cu is 3.0 μm or less, and the BET specific surface area (SSA_Glass) of the glass powder is 1.7-20 m2 / g. <sp / >

Description

External electrode paste

[0001] The present invention relates to a paste for external electrodes.

[0002] Significant demand is expected for multilayer ceramic capacitors (MLCCs) as electronic components for automobiles, mobile phones, and the like. In recent years, there has been a demand for smaller, larger capacitance, higher reliability, and multiple terminals in electronic components, which has led to a demand for thinner and flatter external electrodes in electronic components. However, as external electrodes become thinner, it has been reported that peeling and chipping of the external electrodes occur after the external electrode paste has been applied and dried, especially at corners where the film thickness is thin. Therefore, there is a demand for improving the strength of the external electrode paste applied to electronic components.

[0003] Patent Document 1 discloses an external electrode paste that contains a resin containing an ethyl cellulose-based resin and an acrylic-based resin, at least partially copolymerized, a Cu filler, and a solvent, and that has an interfacial tension of 15 N / m or more between the resin and the solvent. This external electrode paste has sufficient strength to form a dry film.

[0004] Japanese Patent Application Laid-Open No. 2021-77750

[0005] In Patent Document 1, the strength of the dried film is improved by adjusting the interfacial tension between the resin and the solvent. The external electrode paste contains glass powder to bond the laminate and the external electrodes after firing the external electrode paste. The inventors of the present invention discovered that the bulk formed by this glass powder adversely affects moisture resistance reliability. Specifically, the glass powder melts due to the heat generated during firing. Therefore, it is believed that the molten glass powder particles bond together during firing, making it easier for the glass bulk to form. Furthermore, when this bulk extends from the surface of the external electrode to the interface between the external electrode and the laminate, the bulk forms a path for moisture to penetrate into the laminate because glass is more hydrophilic than Cu. This reduces the moisture resistance reliability of the multilayer ceramic capacitor.

[0006] Therefore, a primary object of the present invention is to provide an external electrode paste used to form external electrodes of multilayer ceramic electronic components, which can improve the strength and moisture resistance reliability of the dried film.

[0007] The external electrode paste used to form external electrodes of a multilayer ceramic electronic component according to the present invention contains an acrylic resin and an ethyl cellulose resin, at least a portion of which are copolymerized, a Cu powder, a glass powder, and a solvent, and the D50_Cu of the Cu powder and the D50_Glass of the glass powder obtained by a laser diffraction / scattering particle size distribution measurement method have a ratio of D50_Glass to D50_Cu (D50_Glass / D50_Cu) of 0.13 to 0.67, D50_Cu is 3.0 μm or less, and the BET specific surface area (SSA_Glass) of the glass powder is 1.7 m 2 / g or more 20m 2 / g or less.

[0008] In the external electrode paste, at least a portion of the acrylic resin and the ethyl cellulose resin are copolymerized. Therefore, the dried film obtained by applying this external electrode paste to the body of an electronic component has flexibility, in other words, toughness, derived from the acrylic resin, and rigidity, derived from the ethyl cellulose resin, thereby improving the strength of the dried film. Furthermore, the external electrode paste has a D50_Glass / D50_Cu ratio of 0.13 to 0.67, D50_Cu is 3.0 μm or less, and the BET specific surface area (SSA_Glass) of the glass powder is 1.7 m 2 / g or more 20m 2 / g or less. Therefore, chipping, peeling, and the like can be suppressed in the dried film after the external electrode paste is applied to the body of an electronic component and dried, and the strength of the dried film can be further improved. Furthermore, such an external electrode paste can also improve moisture-resistant reliability. Furthermore, when the external electrode paste is applied to a laminate, the external electrode paste can be suppressed from forming a bulging shape at the end face of the laminate. Therefore, the dried film can be formed flat over substantially the entire end face of the laminate. As described above, by using the external electrode paste, the dried film can be planarized while improving its strength and moisture-resistant reliability. As a result, even when the dried film is flattened and made thinner, the electronic component can be miniaturized while suppressing a decrease in strength and moisture-resistant reliability.

[0009] According to the present invention, it is possible to provide an external electrode paste used for forming external electrodes of a multilayer ceramic electronic component, which can improve the strength and moisture resistance reliability of the dried film.

[0010] The above and other objects, features, and advantages of the present invention will become more apparent from the following detailed description of the preferred embodiments of the present invention, which proceeds with reference to the accompanying drawings.

[0011] 1 is a perspective view showing an example of a multilayer ceramic capacitor as an electronic component according to an embodiment of the present invention; 2 is a cross-sectional view taken along line II-II in FIG. 1; 3 is a diagram illustrating a step of applying an external electrode paste according to the present embodiment to a laminate; 4(a) is a diagram schematically illustrating an LW cross section of a multilayer ceramic capacitor in which external electrodes are formed on a laminate using the external electrode paste according to the present embodiment, and 4(b) is a diagram schematically illustrating an LW cross section of a multilayer ceramic capacitor in which external electrodes are formed on a laminate using a conventional external electrode paste.

[0012] 1. Embodiments An external electrode paste according to an embodiment of the present invention is used to form external electrodes of a multilayer ceramic electronic component. The external electrode paste contains an acrylic resin and an ethyl cellulose resin, at least a portion of which are copolymerized, a Cu powder, a glass powder, and a solvent. Regarding D50_Cu of the Cu powder and D50_Glass of the glass powder, which are obtained by a laser diffraction / scattering particle size distribution measurement method, the ratio of D50_Glass to D50_Cu (D50_Glass / D50_Cu) is 0.13 or more and 0.67 or less. Furthermore, D50_Cu is 3.0 μm or less. Furthermore, the BET specific surface area (SSA_Glass) of the glass powder is 1.7 m. 2 / g or more 20m 2 / g or less.

[0013] The acrylic resin is, for example, at least one of isobutyl methacrylate, methyl methacrylate, hydroxyethyl methacrylate, hydroxypropyl methacrylate, n-butyl methacrylate, and 2-ethylhexyl methacrylate.

[0014] The ethyl cellulose-based resin is, for example, at least one of ethyl cellulose, methyl cellulose, hydroxypropyl cellulose, trityl cellulose, acetyl cellulose, carboxymethyl cellulose, and nitrocellulose.

[0015] The Cu powder is particles made of at least one of Cu and a Cu alloy.

[0016] The glass powder is not particularly limited, but from the viewpoint of promoting the adsorption of Cu powder to the glass powder, it preferably contains B or Bi, and examples thereof include Bi-B-Si-O and Bi-B-Al-Si-O systems. The glass powder may also contain a borosilicate glass composition. A borosilicate glass composition is a glass composition that contains B oxide and Si oxide as network-forming oxides and alkali metal element oxides and alkaline earth metal element oxides as modifying oxides.

[0017] The solvent may include, for example, at least one of terpineol, dihydroterpineol, dihydroterpinyl acetate, propylene glycol phenyl ether, benzyl alcohol, texanol, and butyl carbitol acetate. The solvent species can be analyzed by measuring the evolved gas using gas chromatography-mass spectrometry. Gas chromatography-mass spectrometry can be performed using, for example, a mass spectrometer 7890A / 5975C (heated to 500°C) manufactured by Agilent Technologies, Inc.

[0018] In addition, the external electrode paste may contain various additives such as a dispersant, a plasticizer, an anti-settling agent, and a thixotropic agent.

[0019] The external electrode paste is produced by weighing and mixing at least a partially copolymerized acrylic resin and ethyl cellulose resin, Cu powder, glass powder, and a solvent in a predetermined mixing ratio, and dispersing and kneading the mixture using a three-roll mill or the like.

[0020] As described above, the acrylic resin and the ethyl cellulose resin are at least partially copolymerized. For example, the OH group of the ethyl cellulose resin is substituted with a vinyl group, and the ethyl cellulose resin and the acrylic resin are bonded via the substituted vinyl group.

[0021] When forming external electrodes using an external electrode paste containing Cu powder, baking must be performed at a low oxygen partial pressure in order to prevent blister defects and to prevent oxidation of Cu. That is, it is preferable to use a resin that decomposes even in the presence of little oxygen as a binder, and it is preferable to use a resin that contains a large amount of acrylic resin as such a resin.

[0022] However, if an external electrode paste containing only an ethyl cellulose resin and an acrylic resin without copolymerization is used, the dried film will be brittle. Therefore, electronic components coated with such an external electrode paste may suffer from chipping or peeling of the dried film during transport. This is thought to be due to the following reasons.

[0023] A dried film obtained by applying an external electrode paste containing a resin in which an acrylic resin and an ethyl cellulose resin are at least partially copolymerized to the body of an electronic component has flexibility, in other words, toughness, derived from the acrylic resin, and rigidity derived from the ethyl cellulose resin, and has sufficient strength as a dried film.

[0024] In contrast, in the case of an external electrode paste containing a non-copolymerized acrylic resin and an ethyl cellulose resin, phase separation between the acrylic resin and the ethyl cellulose resin is promoted during the kneading step with Cu powder during the manufacturing process, resulting in segregation of glass powder in the external electrode paste. When an external force is applied to the dried film obtained by applying this external electrode paste to the body of an electronic component, cracks tend to propagate from brittle points such as the interface between the glass segregation and Cu, which is thought to cause chipping or peeling. Chip and peeling of the external electrodes of electronic components can be detected by observing their appearance with an optical microscope.

[0025] Furthermore, in the external electrode paste according to this embodiment, D50_Glass / D50_Cu is 0.13 or more and 0.67 or less, D50_Cu is 3.0 μm or less, and the BET specific surface area of ​​the glass powder (SSA_Glass) is 1.7 m 2 / g or more 20m 2 / g or less. This allows the Cu powder and glass powder to be densely packed within the external electrode paste due to convection during drying of the external electrode paste. This reduces the void ratio in the dried film, thereby improving the strength of the dried film. If the void ratio in the dried film is large, cracks are likely to develop from the voids when the dried film is subjected to an impact. However, with the external electrode paste having the above configuration, the void ratio can be reduced, thereby suppressing the development of cracks and improving the strength of the dried film. Furthermore, with the external electrode paste having the above configuration, the moisture resistance reliability can also be improved.

[0026] To further explain, if the dry film obtained by applying the external electrode paste to the base body of an electronic component has a large void ratio, cracks due to impact tend to propagate, resulting in a decrease in strength. Therefore, to improve the strength of the dry film, it is important to densely pack the Cu powder and glass powder within the external electrode paste to reduce the void ratio. It is also conceivable to improve the dry film strength by reducing the D50_Cu of the Cu powder and / or the D50_Glass of the glass powder, thereby densely packing at least one of the Cu powder and the glass powder within the external electrode paste and reducing the void ratio. However, the inventors of the present invention have found that if the D50_Glass of the glass powder is too large relative to the D50_Cu of the Cu powder, it adversely affects moisture resistance reliability. In other words, if the D50_Glass of the glass powder is too large, it is thought that the glass powder particles will fuse together during firing, easily forming a bulk that connects from the surface of the external electrode to the interface between the external electrode and the laminate. Since glass is more hydrophilic than Cu, the bulk forms a path for moisture to penetrate into the laminate, which is thought to reduce the moisture resistance reliability of the multilayer ceramic capacitor.

[0027] Here, it is conceivable that by making the D50_Glass of the glass powder smaller relative to the D50_Cu of the Cu powder, the glass powder can be densely packed together with the Cu powder in the external electrode paste, reducing the void ratio and improving dry film strength. However, the inventors of the present invention have found that if the D50_Glass of the glass powder relative to the D50_Cu of the Cu powder is too small, the glass powder present between the Cu powder particles is likely to form a bulk that is separated from the Cu powder and connects from the surface of the external electrode to the interface between the external electrode and the laminate, and that this bulk has an adverse effect on moisture resistance reliability as described above.

[0028] In the external electrode paste having the above configuration, by defining D50_Glass / D50_Cu, D50_Cu, and SSA_Glass, the Cu powder and glass powder are made small while the particle size ratio between the Cu powder and the glass powder is adjusted. Therefore, when the external electrode paste having the above configuration is used, the Cu powder and glass powder can be densely packed within the external electrode paste to reduce the void ratio, thereby improving the strength of the dried film and further suppressing the formation of bulk extending from the external electrode surface to the interface between the external electrode and the laminate, thereby improving moisture resistance reliability.

[0029] Furthermore, when the external electrode paste is applied to a laminate, the external electrode paste can be prevented from swelling at the end faces of the laminate, and thus a flat dried film can be formed over substantially the entire end faces of the laminate.

[0030] As described above, by using the above-described external electrode paste, it is possible to flatten the dry film while improving its strength and moisture-resistant reliability, thereby enabling miniaturization of electronic components while suppressing a decrease in strength and moisture-resistant reliability even when the dry film is flattened and thinned.

[0031] The BET specific surface area of ​​the target substance (glass powder) can be measured by a method in which gas molecules with a known adsorption area are adsorbed onto the surface of the target substance and the specific surface area of ​​the target substance is measured from the amount of adsorption of the gas molecules. The BET specific surface area was measured using an MR-6 (manufactured by Microtrac Bell) as a BET specific surface area evaluation device, and after degassing at 150°C for 20 minutes, the measurement was performed using the BET single-point method.

[0032] Next, a process for applying the external electrode paste to the laminate in this embodiment will be described. Fig. 1 is an external perspective view showing an example of a multilayer ceramic capacitor as an electronic component according to an embodiment of the present invention. Fig. 2 is a cross-sectional view taken along line II-II in Fig. 1. Fig. 3 is a view for explaining the process for applying the external electrode paste to the laminate in this embodiment.

[0033] First, a multilayer ceramic capacitor formed by applying an external electrode paste will be described. As shown in Figures 1 and 2, the multilayer ceramic capacitor 10 includes a rectangular parallelepiped laminate 12 having internal electrode layers 16 therein, and external electrodes 30 disposed at both ends of the laminate 12.

[0034] The laminate 12 has a first main surface 12a and a second main surface 12b that face each other in a height direction x (stacking direction), a first side surface 12c and a second side surface 12d that face each other in a width direction y that is perpendicular to the height direction x, and a first end surface 12e and a second end surface 12f that face each other in a length direction z that is perpendicular to the height direction x and the width direction y.

[0035] The laminate 12 includes a plurality of ceramic layers 14. The plurality of ceramic layers 14 are stacked in a height direction x. The dielectric material forming the ceramic layers 14 may be, for example, a dielectric ceramic containing a component such as BaTiO, CaTiO, SrTiO, or CaZrO.

[0036] When a piezoelectric ceramic material is used for the ceramic layer 14, the electronic component functions as a piezoelectric component. Specific examples of piezoelectric ceramic materials include PZT (lead zirconate titanate) ceramic materials. When a semiconductor ceramic material is used for the ceramic layer 14, the electronic component functions as a thermistor element. Specific examples of semiconductor ceramic materials include spinel ceramic materials. When a magnetic ceramic material is used for the ceramic layer 14, the electronic component functions as an inductor element. When functioning as an inductor element, the internal electrode layer 16 becomes a coil-shaped conductor. Specific examples of magnetic ceramic materials include ferrite ceramic materials.

[0037] The laminate 12 has a plurality of first internal electrode layers 16a extending to the first end face 12e and a plurality of second internal electrode layers 16b extending to the second end face 12f as the plurality of internal electrode layers 16. The plurality of first internal electrode layers 16a and the plurality of second internal electrode layers 16b are embedded so as to be alternately arranged at equal intervals with the ceramic layers 14 sandwiched between them along the height direction x of the laminate 12.

[0038] As shown in FIGS. 1 and 2, external electrodes 30 are disposed on the first end face 12e side and the second end face 12f side of the laminate 12.

[0039] The external electrode 30 includes a first external electrode 30a and a second external electrode 30b.

[0040] The first external electrode 30a is disposed on at least the surface of the first end face 12e and is connected to the first internal electrode layer 16a. In this embodiment, the first external electrode 30a extends from the first end face 12e and is disposed on a part of the first main face 12a, a part of the second main face 12b, a part of the first side face 12c, and a part of the second side face 12d.

[0041] The second external electrode 30b is disposed on at least the surface of the second end face 12f and is connected to the second internal electrode layer 16b. In this embodiment, the second external electrode 30b extends from the second end face 12f and is disposed on a part of the first main face 12a, a part of the second main face 12b, a part of the first side face 12c, and a part of the second side face 12d.

[0042] When forming external electrodes 30 on such a multilayer ceramic capacitor 10, the regions of the laminate 12 where the external electrodes 30 are to be formed are immersed in external electrode paste 31 (see FIG. 3( a)) and then pulled up (see FIG. 3( b)). The regions where the external electrodes 30 are to be formed are, for example, both end faces (first end face 12 e) and second end face 12 f) of the laminate 12. Here, the external electrode paste attached to the laminate 12 is denoted by the reference symbol 31 a in the following description. When the laminate 12 is pulled up, Marangoni convection occurs as indicated by the arrows in FIG. 3( b) due to temperature differences and solute concentration differences between the center and end portions of the external electrode paste 31 a attached to the laminate 12. The solutes are Cu powder, glass powder, and resin contained in the external electrode paste.

[0043] Because the amount of external electrode paste applied is smaller at the edges than at the center, drying proceeds more quickly at the edges. Therefore, the proportion of resin in the external electrode paste is higher at the edges than at the center, making it energetically unstable, resulting in an outward flow of the external electrode paste from the center to the edges (see FIG. 3( c)). This outward flow occurs as long as the resin concentration at the edges is higher than that at the center. It is believed that as drying proceeds, the number of interfaces between the solute and the solvent increases, making it energetically unstable and strengthening the outward flow.

[0044] Here, the ethyl cellulose resin has rigidity and high heat storage capacity, and therefore prevents the external electrode paste from solidifying during flow in the drying process and plays a role in promoting outward flow. The generation of a strong outward flow causes the external electrode paste to flow from the center to the edges, making it possible to prevent the external electrode paste from bulging outward in the center (see FIG. 3(d)).

[0045] Fig. 4(a) is a diagram schematically showing an LW cross section of a multilayer ceramic capacitor in which external electrodes are formed on a laminate using the external electrode paste of the present embodiment, and Fig. 4(b) is a diagram schematically showing an LW cross section of a multilayer ceramic capacitor in which external electrodes are formed on a laminate using a conventional external electrode paste.

[0046] As shown in FIG. 4( b ), in the conventional multilayer ceramic capacitor 1, the first external electrode 3 a is formed on the laminate 12 using a conventional external electrode paste. The first external electrode 3 a has a convex shape with a thick center and a thin edge. In contrast, as shown in FIG. 4( a ), in the multilayer ceramic capacitor 10 of this embodiment, the first external electrode 30 a is formed on the laminate 12 using the external electrode paste of this embodiment. The first external electrode 30 a has a flat shape over the entire end face of the laminate 12, preventing the above-mentioned convex shape. The second external electrode 30 b is also formed with a similar flat shape. Therefore, the multilayer ceramic capacitor 10 having the external electrode 30 formed using the external electrode paste of this embodiment can be miniaturized. Furthermore, when compared at the same size, the external electrode 30 can be made thinner and the internal element can be made larger, thereby enabling a larger capacitance.

[0047] It should be noted that the method for applying the external electrode paste to the laminate 12 in this embodiment is not limited to the above-described method of immersion in the external electrode paste.

[0048] As described above, by using the external electrode paste of this embodiment, it is possible to flatten the dry film while improving its strength and moisture-resistant reliability, thereby making it possible to miniaturize electronic components while suppressing a decrease in strength and moisture-resistant reliability even when the dry film is flattened and made thinner.

[0049] In addition, in the external electrode paste, it is preferable that the D50_Glass of the glass powder is 0.9 μm or less. In this case, since the D50_Glass of the glass powder can be reduced, the glass powder is packed more densely in the external electrode paste due to convection during drying of the external electrode paste. As a result, the void ratio in the dried film can be further reduced, and the strength of the dried film can be further improved.

[0050] Furthermore, in the above-mentioned external electrode paste, the ratio of Cu powder and glass powder to non-volatile components other than the solvent ((volume of Cu powder and volume of glass powder) / (volume of non-volatile components other than the solvent)) is preferably 50% by volume or more and 70% by volume or less. In this case, shape defects such as wrinkles can be suppressed in the dried film obtained after drying the external electrode paste, thereby further improving the strength of the dried film.

[0051] If the ratio exceeds 70% by volume, wrinkles will appear in the dried film when the external electrode paste dries, reducing its strength. If the ratio is less than 50% by volume, the acrylic resin and ethyl cellulose resin will adsorb to the Cu powder and glass powder, reducing the network chains formed. This results in a larger network and a lower crosslink density, reducing the strength of the dried film.

[0052] Furthermore, in the external electrode paste, the weight ratio of the acrylic resin to the ethyl cellulose resin is preferably 3:7 to 7:3. In this case, segregation of the Cu powder and glass powder in the external electrode paste can be suppressed, thereby suppressing stress concentration in a dried film using the external electrode paste, thereby improving the strength of the dried film.

[0053] 2. Experimental Examples Next, experimental examples will be specifically described. Experimental Examples 1 and 2 were performed. In Experimental Example 1, the weight ratio of the acrylic resin to the ethyl cellulose resin was set to 5:5, and the ratio of the Cu powder and the glass powder to the non-volatile components other than the solvent was set to 60 volume %, and the D50_Cu of the Cu powder was changed while the D50_Glass (BET specific surface area (SSA_Glass)) of the glass powder was changed. In Experimental Example 2, the weight ratio of the acrylic resin to the ethyl cellulose resin was changed while the ratio of the Cu powder and the glass powder to the non-volatile components other than the solvent was changed. In addition, in the experimental example, a laminate having an L dimension in the length direction z of 0.6 mm, a W dimension in the width direction y of 0.3 mm, and a T dimension in the height direction x of 0.3 mm was used.

[0054] (1) Experimental Example 1 Experimental Example 1 will be described below.

[0055] A. Sample Preparation For each of Examples 1 to 5 and Comparative Examples 1 to 4, an acrylic resin, an ethyl cellulose resin, a Cu powder, a glass powder, and a solvent were prepared. For each of Examples 1 to 5, Cu powders with D50_Cu of 0.15 μm, 0.75 μm, 0.32 μm, 1.5 μm, and 3.0 μm were prepared. For each of Examples 1 to 5, glass powders with D50_Glass and SSA_Glass of 0.10 μm and 20 μm were prepared. 2 / g, 0.10 μm and 20 m 2 / g, 0.21 μm and 8.3 m 2 / g, 0.45 μm and 3.3 m 2 / g, 0.90 μm and 1.7 m 2 For the Cu powders of Comparative Examples 1 to 4, D50_Cu particles of 0.32 μm, 1.5 μm, 1.5 μm, and 3.1 μm were prepared. For the glass powders of Comparative Examples 1 to 4, D50_Glass and SSA_Glass particles of 0.32 μm and 6.3 μm were prepared. 2 / g, 0.10 μm and 20 m 2 / g, 1.0 μm and 1.5 m 2 / g, 0.60 μm and 2.8 m 2 In this specification, D50_Glass of the glass powder refers to a sphere-equivalent diameter, and specifically refers to a particle size at which the cumulative frequency is 50% in the particle size distribution of the powder measured by a laser diffraction / scattering particle size distribution measurement method.

[0056] In each of the samples of Examples 1 to 5 and Comparative Examples 1 to 4, the weight ratio of the acrylic resin to the ethyl cellulose resin was 5:5, and the ratio of the Cu powder and the glass powder to the non-volatile components other than the solvent was 60% by volume. For each sample, the acrylic resin, the ethyl cellulose resin, the Cu powder, the glass powder, and the solvent were blended so as to be 5% by weight, 50% by weight, 5% by weight, and 40% by weight, respectively, and mixed in a planetary mixer. After that, the mixture was dispersed and kneaded in a three-roll mill to prepare a sample of an external electrode paste.

[0057] B. Evaluation of Samples (Dry Film Strength Test) A portion of the laminate was immersed in each of the prepared samples, and then the laminate coated with the sample was pulled out. The laminate coated with each sample was dried at a temperature of 150°C for 10 minutes. 100 laminates were used for each sample. After drying, each laminate was subjected to vibration at a frequency of 50 Hz for 1 minute at a temperature of 25°C using an MRV-MINI-M (manufactured by Wastec Co., Ltd.). Each laminate was observed with a metallurgical microscope to check for defects such as chipping and peeling in the dried film. Products with no chipping or peeling were rated as good products (◯), and products with chipping or peeling were rated as defective products (×).

[0058] (Moisture Resistance Reliability Test) Based on the PCBT test method, 20 samples were prepared for each of Examples 1 to 5 and Comparative Examples 1 to 4, and a moisture resistance reliability test was conducted. More specifically, each sample was first mounted on a mounting board using solder. Subsequently, the insulation resistance value IR of each sample was measured (insulation resistance value 1 hour after the start of the moisture resistance reliability test). Next, the mounting board was placed in a high-temperature, high-humidity chamber, and a direct current of 4 V was applied between the first and second external electrodes of each sample under an environment of 85°C and 85% RH for 200 hours (moisture resistance reliability test time). After the moisture resistance reliability test, the insulation resistance value IR of each sample was measured (insulation resistance value after moisture resistance reliability test time). If even one of the 20 samples showed a decrease in IR by more than two orders of magnitude compared to the IR before the moisture resistance reliability test, the sample was deemed defective and marked with an "X." If all 20 samples showed a decrease of less than two orders of magnitude, the sample was deemed non-defective and marked with an "O."

[0059] (Overall Evaluation) When the result was "◯" in both the dry film strength test and the moisture resistance reliability test, the product was deemed to be a good product and the overall evaluation was "◯", and when the result was "×" in either the dry film strength test or the moisture resistance reliability test, the product was deemed to be a defective product and the overall evaluation was "×".

[0060] Table 1 shows the results of the evaluation for each sample.

[0061]

[0062] C. Results The overall evaluation for Examples 1 to 5 was "Good." In Examples 1 to 5, D50_Glass / D50_Cu was 0.13 or more and 0.67 or less. D50_Cu was 3.0 μm or less. SSA_Glass was 1.7 μm or less. 2 / g or more 20m 2 Therefore, it is preferable that D50_Glass / D50_Cu, D50_Cu, and SSA_Glass are in the above-mentioned ranges.

[0063] Furthermore, D50_Glass was 0.9 μm or less in Examples 1 to 5. Therefore, it is preferable that D50_Glass is 0.9 μm.

[0064] On the other hand, the D50_Glass / D50_Cu of Comparative Example 1 was 1.0, which was not within the range of 0.13 or more and 0.67 or less, and the dry film strength was "×". Furthermore, the D50_Glass / D50_Cu of Comparative Example 2 was 0.067, which was not within the range of 0.13 or more and 0.67 or less, and the moisture resistance reliability was "×". The SSA_Glass of Comparative Example 3 was 1.5 m 2 / g, and 1.7m 2 / g or more 20m 2 / g or less, and the moisture resistance reliability was "x". D50_Cu of Comparative Example 4 was 3.1 μm, which exceeded 3.0 μm, and the dry film strength was "x".

[0065] (2) Experimental Example 2 Experimental Example 2 will be described below.

[0066] A. Sample Preparation Acrylic resin, ethyl cellulose resin, Cu powder, glass powder, and solvent were prepared. The D50_Cu of the Cu powder was 0.3 μm. The D50_Glass of the glass powder was 0.21 μm. Furthermore, samples were prepared in which the weight ratio (AC:EC in Table 2) of the acrylic resin (AC) to the ethyl cellulose resin (EC in Table 2) was varied to 1:9, 2:8, 3:7, 4:6, 5:5, 6:4, 7:3, 8:2, and 9:1, and the ratio of Cu powder and glass powder to nonvolatile components other than the solvent ((volume of Cu powder and volume of glass powder) / (volume of nonvolatile components other than the solvent)) was varied to 45 vol%, 50 vol%, 55 vol%, 60 vol%, 65 vol%, 70 vol%, and 75 vol%. The weight ratio of Cu powder to glass powder was 50:5. The solvent was 35 wt% of the mixture of acrylic resin, ethyl cellulose resin, Cu powder, glass powder, and solvent. The acrylic resin, ethyl cellulose resin, Cu powder, glass powder, and solvent were mixed in a planetary mixer, and then dispersed and kneaded in a three-roll mill to prepare external electrode paste samples. The 63 types of samples prepared were listed in Table 2 below.

[0067] B. Evaluation of Samples Each sample was subjected to a dry film strength test, which was the same as in Experimental Example 1.

[0068] Table 2 shows the results of the evaluation for each sample.

[0069]

[0070] C. Results When the ratio of Cu powder and glass powder to non-volatile components other than the solvent was 45% by volume and 75% by volume, the evaluation result was "X". Therefore, it is preferable that the ratio of Cu powder and glass powder to non-volatile components other than the solvent is greater than 45% by volume and less than 75% by volume. More preferably, the ratio is 50% by volume or more and 70% by volume or less.

[0071] Furthermore, when the weight ratio of the acrylic resin to the ethyl cellulose resin was 1:9, 2:8, 8:2, or 9:1, the result of the evaluation was "X." Therefore, assuming that the sum of the weight ratios of the acrylic resin and the ethyl cellulose resin is 10, it is preferable that the acrylic resin is more than 2 and less than 8, and that the ethyl cellulose resin is less than 8 and more than 2. More preferably, the weight ratio is 3:7 to 7:3.

[0072] As described above, although the embodiments of the present invention have been disclosed in the above description, the present invention is not limited thereto. In other words, various modifications can be made to the above-described embodiments in terms of mechanism, shape, material, quantity, position, arrangement, etc., without departing from the scope of the technical idea and purpose of the present invention, and such modifications are included in the present invention.

[0073] <1> An external electrode paste used to form external electrodes of a multilayer ceramic electronic component, comprising: an acrylic resin and an ethyl cellulose resin, at least a portion of which are copolymerized; a Cu powder; a glass powder; and a solvent, wherein, with respect to D50_Cu of the Cu powder and D50_Glass of the glass powder obtained by a laser diffraction / scattering particle size distribution measurement method, the ratio of D50_Glass to D50_Cu (D50_Glass / D50_Cu) is 0.13 or more and 0.67 or less, D50_Cu is 3.0 μm or less, and the BET specific surface area (SSA_Glass) of the glass powder is 1.7 m 2 / g or more 20m 2 / g or less.

[0074] <2> The external electrode paste according to <1>, wherein the D50_Glass is 0.9 μm or less.

[0075] <3> The external electrode paste according to <1> or <2>, wherein the ratio of the Cu powder and the glass powder to the non-volatile components other than the solvent is 50% by volume or more and 70% by volume or less.

[0076] <4> The paste for external electrodes according to any one of <1> to <3>, wherein the weight ratio of the acrylic resin to the ethyl cellulose resin is 3:7 to 7:3.

[0077] 10: Multilayer ceramic capacitor 12: Laminate 12a: First main surface 12b: Second main surface 12c: First side surface 12d: Second side surface 12e: First end surface 12f: Second end surface 14: Ceramic layer 16: Internal electrode layer 16a: First internal electrode layer 16b: Second internal electrode layer 30: External electrode 30a: First external electrode 30b: Second external electrode 31: External electrode paste 31a: External electrode paste x: Height direction y: Width direction z: Length direction

Claims

1. An external electrode paste used to form external electrodes of a multilayer ceramic electronic component, comprising: an acrylic resin and an ethyl cellulose resin, at least a portion of which are copolymerized; a Cu powder; a glass powder; and a solvent, wherein, with respect to D50_Cu of the Cu powder and D50_Glass of the glass powder obtained by a laser diffraction scattering type particle size distribution measurement method, the ratio of D50_Glass to D50_Cu (D50_Glass / D50_Cu) is 0.13 to 0.67, D50_Cu is 3.0 μm or less, and the BET specific surface area (SSA_Glass) of the glass powder is 1.7 m. 2 / g or more 20m 2 / g or less.

2. The paste for external electrodes according to claim 1, wherein the D50_Glass is 0.9 μm or less.

3. The external electrode paste according to claim 1 or 2, wherein the ratio of the Cu powder and the glass powder to the non-volatile components other than the solvent is 50 volume % or more and 70 volume % or less.

4. The external electrode paste according to any one of claims 1 to 3, wherein the weight ratio of said acrylic resin to said ethyl cellulose resin is 3:7 to 7:3.

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