JP2008227364A - Internal electrode formation paste, lamination layer ceramic type electronic component, and method of manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a paste capable of obtaining a sufficient adhesion force without increasing an amount of a binder even when fine electrode material powder is used in an internal electrode formation paste for screen printing. <P>SOLUTION: An internal electrode formation paste for screen printing includes electrode material powder, main electrode material powder, an ethylcellulose system resin as a main binder, alkylphenol resin and at least one kind of resin chosen from a group consisting of terpene resins having a number average molecular weight of 700 or less as a sub binder. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to an internal electrode forming paste for screen printing, a multilayer ceramic electronic component manufactured using the internal electrode forming paste, and a method for manufacturing the multilayer ceramic electronic component.

  In recent years, miniaturization and high performance of multilayer electronic components such as multilayer ceramic capacitors have been demanded due to miniaturization of electronic devices. In the manufacture of this type of multilayer ceramic capacitor, a green sheet is usually laminated via an internal electrode precursor layer to form a laminate. This laminated body is cut into predetermined dimensions, and subjected to binder removal processing, firing processing, and heat treatment to obtain a sintered body. A capacitor is completed by forming a terminal electrode on the sintered body. The electrode precursor layer is formed by printing a paste containing electrode material powder and a binder.

  In order to promote downsizing and high performance of electronic components, the dielectric layer thickness and electrode layer thickness are 1 μm or less, and the number of stacked layers has exceeded 800 layers. The particle diameter of the electrode material powder conventionally used is about 0.4 μm. For this reason, when the thickness of the electrode layer is 1 μm or less, the number of particles of the electrode material powder arranged in the thickness direction of the electrode layer is 2 to 3, making it difficult to form a homogeneous electrode layer. In addition, such an electrode layer has insufficient surface roughness, and is likely to cause short circuit failure and breakdown voltage failure.

 In order to form the electrode layer thinner and more uniformly, it is considered to use fine electrode material powder. However, when fine electrode material powder is used, the total surface area of the electrode material powder of the same weight increases. For this reason, when the amount of binder is constant, the amount of binder per particle surface area decreases. As a result, since the adhesive force is reduced, stacking defects such as sheet misalignment and delamination may occur when the green sheets are stacked. In addition, since the shape retention of the laminate is reduced, chip cracking and cracking may occur during heat treatment (binder removal and firing).

  For this reason, the method of improving the adhesiveness at the time of lamination | stacking by increasing the amount of binders and preventing a lamination | stacking defect can be considered. However, when the amount of the binder increases, it becomes difficult to remove the binder, which causes a problem that chip cracks and cracks increase during the heat treatment.

  In Patent Document 1, as a paste for forming this type of electrode precursor layer, “a gravure printing ink containing at least an inorganic powder, a binder resin, and an organic solvent, wherein the binder resin is an ethyl cellulose resin; At least one low molecular weight resin having a number average molecular weight of 300 to 5,000 and selected from terpene resins, terpene phenol resins, petroleum resins, polybutadiene resins, polyisoprene resins and polyether resins; And a gravure printing ink characterized in that the content of the low molecular weight resin is 0.5 to 10% by weight.

The viscosity of gravure printing ink is generally about 0.3 to 2 (dPa · s), and is not applicable to screen printing. In order to improve productivity and form a thin electrode layer, it is effective to adopt a screen printing method.
JP 2005-126505 A

  The present invention has been made in view of such a situation, and a sufficient adhesive force can be obtained without increasing the amount of binder even when a fine electrode material powder is used in an internal electrode forming paste for screen printing. The purpose is to provide a paste that can be used.

  As a result of intensive studies to achieve the above object, the present inventors have found that the above object can be achieved by using a binder having a specific composition as the binder constituting the internal electrode forming paste, The present invention has been completed.

  That is, this invention which solves the said subject contains the following matter as a summary.

(1) electrode material powder;
Ethyl cellulose resin as the main binder;
An internal electrode forming paste for screen printing, comprising at least one resin selected from the group consisting of an alkylphenol resin and a terpene resin having a number average molecular weight of 700 or less as a secondary binder.

(2) The internal electrode forming paste according to (1), wherein the number average molecular weight of the ethylcellulose-based resin is 10,000 to 200,000.

(3) The internal electrode forming paste according to (1) or (2), wherein the glass transition point of the auxiliary binder is 50 ° C. or lower.

(4) The internal electrode forming paste according to any one of (1) to (3), wherein the secondary binder is a terpene resin and includes 20 to 80 parts by weight of the secondary binder with respect to 100 parts by weight of the main binder.

(5) The internal electrode forming paste according to any one of (1) to (3), wherein the sub binder is an alkylphenol resin and includes 70 to 90 parts by weight of the sub binder with respect to 100 parts by weight of the main binder.

(6) The internal electrode forming paste according to any one of (1) to (5), which includes 4.2 to 6.65 parts by weight of the main binder and the sub binder in total with respect to 100 parts by weight of the electrode material powder. .

(7) The internal electrode forming paste according to any one of (1) to (6), wherein the electrode material powder contains Ni.

(8) The internal electrode forming paste according to any one of (1) to (7), wherein an average particle size of the electrode material powder is 0.05 to 0.3 μm.

(9) A multilayer ceramic electronic component having an internal electrode layer manufactured using the internal electrode forming paste according to any one of (1) to (8) and a dielectric layer.

(10) The multilayer ceramic electronic component according to (9), wherein the internal electrode layer has a thickness of 1.0 μm or less.

(11) A step of preparing the internal electrode forming paste according to any one of (1) to (8),
Forming a dielectric green sheet;
A step of screen-printing the internal electrode forming paste on the dielectric green sheet to form an internal electrode precursor layer;
Laminating a plurality of dielectric green sheets having internal electrode precursor layers formed thereon to form a laminate;
Firing the laminate;
A method of manufacturing a multilayer ceramic electronic component having

(12) The method for producing a multilayer ceramic electronic component according to (11), wherein the dielectric green sheet includes dielectric powder and an acrylic resin as a binder.

 ADVANTAGE OF THE INVENTION According to this invention, even if it is a case where fine electrode material powder is used in the internal electrode formation paste for screen printing, the paste which can obtain sufficient adhesive force without increasing the amount of binders is provided.

  Since the adhesive force is maintained, occurrence of stacking faults such as sheet misalignment and delamination (delamination) during green sheet stacking is reduced. Further, the shape retention of the laminate is maintained, and chip cracking and cracking are reduced during heat treatment (binder removal and firing). As a result, a multilayer ceramic electronic component having a thin electrode layer can be manufactured with high yield.

  Hereinafter, the internal electrode forming paste, the multilayer ceramic electronic component, and the manufacturing method thereof according to the present invention will be described more specifically.

  The internal electrode forming paste according to the present invention includes an electrode material powder, an ethyl cellulose resin as a main binder, and at least one resin selected from the group consisting of a terpene resin and an alkylphenol resin as a sub binder. .

  By using ethyl cellulose resin and a specific sub-binder together, an internal electrode forming paste that can provide sufficient adhesive force without increasing the amount of binder even when fine electrode material powder is used. can get.

 As the ethylcellulose-based resin as the main binder, various commercially available ethylcellulose-based resins are used without particular limitation. In the present invention, the number average molecular weight is particularly preferably 10,000 to 200,000, and more preferably 2 10,000 to 100,000, particularly preferably 50,000 to 100,000 ethylcellulose resins are used.

 When the number average molecular weight of the ethyl cellulose resin is too low, the paste viscosity is lowered, and as a result, there is a risk that paste sagging or bleeding may occur during printing of the internal electrode forming paste. Moreover, printing unevenness may occur due to a decrease in paste viscosity, and a uniform electrode pattern may not be formed. On the other hand, when the number average molecular weight of the ethyl cellulose resin is too high, the paste viscosity becomes high, the coating property is lowered, and it may be difficult to form a thin electrode layer.

 In addition, the number average molecular weight of ethylcellulose-type resin is the value which measured with the GPC apparatus and was converted into polystyrene.

  The binder component of the internal electrode forming paste of the present invention is at least one resin selected from the group consisting of the above-mentioned ethyl cellulose resin as a main binder and an alkylphenol resin as a secondary binder and a terpene resin having a number average molecular weight of 700 or less. Is further contained.

 As the alkylphenol resin and terpene resin as the secondary binder, various commercially available alkylphenol resins and terpene resins are used without particular limitation. In the present invention, the glass transition point is particularly preferably 50 ° C. or less, more preferably -20 to 40 ° C. alkylphenol resin and terpene resin are used.

 If the glass transition point of the secondary binder is too high, the adhesion between the sheets during lamination may not be improved sufficiently.

 In addition, the glass transition point of resin which comprises a subbinder was measured by the measurement temperature range -100 degreeC-+120 degreeC, and the temperature increase rate of 10 degree-C / min using EXII6000 DSC6220 by SII.

 Moreover, when using an alkylphenol resin as a subbinder, it is especially desirable that the compounding quantity is 70-90 weight part with respect to 100 weight part of main binders, Preferably it is 80-90 weight part. By using the alkylphenol resin at such a blending ratio, the effects of the present invention are more reliably exhibited.

 Moreover, when using a terpene resin as a secondary binder, the number average molecular weight is 700 or less, Preferably it is 300-700. In this case, the blending amount of the terpene resin is particularly preferably 20 to 80 parts by weight, preferably 60 to 80 parts by weight with respect to 100 parts by weight of the main binder. By using a terpene resin having such a specific number average molecular weight at a specific blending ratio, the effect of the present invention is more reliably exhibited.

 In the internal electrode forming paste of the present invention, the total amount of the main binder and the sub binder is preferably 4.2 to 6.65 parts by weight, more preferably 5.95 to 100 parts by weight of the electrode material powder. 6.65 parts by weight is blended.

 As described above, by using a specific main binder and sub-binder in combination, even when a fine electrode material powder is used, there is a paste that can obtain a sufficient adhesive force without increasing the amount of the binder. Provided.

 Therefore, the internal electrode forming paste of the present invention is particularly useful when a fine electrode material powder is used. For this reason, the average particle diameter of the electrode material powder is preferably 0.05 to 0.30 μm, more preferably 0.1 to 0.25 μm.

 When fine electrode material powder is used to form the electrode layer thinner and more uniformly, the total surface area of the electrode material powder of the same weight increases. For this reason, when the amount of binder is constant, the amount of binder per particle surface area decreases. As a result, the adhesive strength is reduced, resulting in poor stacking. However, according to the internal electrode forming paste of the present invention, sufficient adhesion can be obtained without increasing the amount of binder by using a specific main binder and sub binder together.

 As electrode material powder (conductor material) used for manufacturing the internal electrode forming paste, Ni, Ni alloy, or a mixture thereof is preferably used. The electrode material powder has a spherical shape or a flake shape, but the shape is not particularly limited. Further, a mixture of these shapes may be used. The average particle diameter of the electrode material powder is not particularly limited, but when the particle shape is spherical, it is about 0.05 to 0.5 μm, preferably about 0.2 to 0.4 μm. In particular, the internal electrode forming paste of the present invention is particularly useful in a fine electrode material powder for realizing a thin and high density, and even if the average particle diameter is about 0.05 to 0.30 μm, the amount of binder Adhesive strength can be obtained without increasing the amount.

 The average particle diameter of the electrode material powder was obtained by applying an electrode paste to a metal holder for SEM imaging and drying it, taking an SEM photograph, and measuring the particle diameter of the electrode material powder from the photograph. The number of measurements was 200, and the average particle size was determined.

  The internal electrode forming paste of the present invention contains the electrode material powder and a binder component as essential components, but may further contain a resin component and a solvent other than those described above as necessary. Further, the internal electrode forming paste may contain the same ceramic powder (co-material) as the ceramic powder contained in the dielectric green sheet paste described later. By including the co-material, it is possible to moderately suppress sintering in the firing process of the metal that is the electrode material powder, and to form an internal electrode layer having a sufficient effective area.

  A dispersing agent is included as a resin component other than the above, which may be included in the internal electrode forming paste. Although it does not specifically limit as a dispersing agent, A polystyrene glycol type dispersing agent, a polycarboxylic acid type dispersing agent, an ester type dispersing agent, an ether type dispersing agent, etc. are illustrated. The dispersant is preferably contained in an amount of 0.1 to 10 parts by weight with respect to 100 parts by weight of the electrode material split weight. If the dispersant content is too small, the effect of addition becomes insufficient, and if it is too large, there may be a disadvantage of a decrease in dispersibility due to micelle formation or reaggregation.

 Examples of the solvent that may be contained in the internal electrode forming paste include terpineol, alcohol, butyl carbitol, acetone, methyl ethyl ketone (MEK), toluene, xylene, ethyl acetate, butyl stearate, isobornyl acetate, and the like. . The content of the solvent contained in the internal electrode forming paste is not particularly limited, but is preferably 60% by weight or less, preferably 50 to 60% by weight with respect to the total amount of the internal electrode forming paste.

  The internal electrode forming paste may contain a plasticizer in order to improve adhesion. Examples of the plasticizer include phthalic acid esters such as benzylbutyl phthalate (BBP), adipic acid, phosphoric acid esters, glycols, and the like. The plasticizer is contained in an amount of 150 parts by weight or less, preferably 25 parts by weight or more and 150 parts by weight or less, and more preferably 25 to 100 parts by weight with respect to 100 parts by weight of the total binder resin. By adding the plasticizer, the adhesive force of the internal electrode layer formed using the paste is increased, and the adhesive force between the internal electrode layer and a green sheet described later is improved.

  The internal electrode forming paste according to the present invention can be obtained by mixing the electrode material powder, the main binder, the sub-binder, and other components used as necessary by an appropriate method. For example, electrode material powder, a binder, a common material, a solvent, a dispersing agent, etc. are prepared and mixed by a three-roll. Thereafter, a dispersant is added and mixed again with three rolls to obtain a paste excellent in dispersibility of the electrode material powder and the co-material.

Moreover, the viscosity at 25 ° C. of the internal electrode paste of the present invention is preferably 20 to 150 dPa · s, more preferably 50 to 120 dPa · s, and particularly preferably 60 to 100 dPa · s. When the paste viscosity is within this range, the electrode precursor layer can be easily formed by screen printing.
The viscosity of the electrode paste is a value at V50 using TA Instruments Model-AR2000ETC.

 The internal electrode forming paste according to the present invention is preferably used for forming internal electrode layers in multilayer ceramic electronic components such as capacitors, piezoelectric elements, PTC thermistors, NTC thermistors and varistors.

 In order to form the internal electrode layer of such a multilayer ceramic electronic component thinner and more uniformly, it is necessary to use a finer electrode material powder as the electrode material powder contained in the internal electrode forming paste. However, when fine electrode material powder is used, the total surface area of the electrode material powder of the same weight increases. For this reason, when the amount of binder is constant, the amount of binder per particle surface area decreases. As a result, since the adhesive strength is reduced, a stacking failure may occur when the green sheets are stacked.

 However, as described above, according to the internal electrode forming paste of the present invention, by using a specific main binder and sub-binder together, the amount of the binder can be reduced even when fine electrode material powder is used. Adhesive strength can be obtained without increasing. Therefore, the internal electrode forming paste of the present invention is particularly useful for forming a thin internal electrode layer. The thickness of the internal electrode layer in the multilayer ceramic electronic component using the internal electrode forming paste of the present invention is preferably 1.0 μm or less, preferably 0.4 to 1.0 μm, more preferably 0.5 to 0.8 μm. It is.

 Next, an embodiment of a multilayer ceramic electronic component using the internal electrode forming paste of the present invention will be described by taking a multilayer ceramic capacitor as an example, but the present invention is not limited to such an embodiment. First, the overall configuration of the multilayer ceramic capacitor will be described.

  As shown in FIG. 1, the multilayer ceramic capacitor 2 according to this embodiment includes a capacitor body 4, a first terminal electrode 6, and a second terminal electrode 8. The capacitor body 4 includes dielectric layers 10 and internal electrode layers 12, and the internal electrode layers 12 are alternately stacked between the dielectric layers 10. The internal electrode layer 12 is formed using the internal electrode forming paste of the present invention. One internal electrode layer 12 that is alternately stacked is electrically connected to the inside of the first terminal electrode 6 that is formed outside one end of the capacitor body 4. The other internal electrode layers 12 stacked alternately are electrically connected to the inside of the second terminal electrode 8 formed outside the other end of the capacitor body 4.

  The material of the dielectric layer 10 is not particularly limited, and is made of a dielectric material such as calcium titanate, strontium titanate and / or barium titanate. The thickness of each dielectric layer 10 is not particularly limited, but is generally several μm to several hundred μm. In particular, in this embodiment, the thickness is preferably 5 μm or less, more preferably 3 μm or less, and particularly preferably 1.0 μm or less. The internal electrode layer 12 is also thinned to 1.0 μm or less, preferably 0.4 to 1.0 μm, more preferably 0.5 to 0.9 μm.

  The material of the terminal electrodes 6 and 8 is not particularly limited, but usually copper, copper alloy, nickel, nickel alloy or the like is used. Also, silver or an alloy of silver and palladium can be used. The thickness of the terminal electrodes 6 and 8 is not particularly limited, but is usually about 10 to 50 μm.

  The shape and size of the multilayer ceramic capacitor 2 may be appropriately determined according to the purpose and application. When the multilayer ceramic capacitor 2 has a rectangular parallelepiped shape, it is usually vertical (0.6 to 5.6 mm, preferably 0.6 to 3.2 mm) × horizontal (0.3 to 5.0 mm, preferably 0.3 to 1.6 mm) × thickness (0.1 to 1.9 mm, preferably 0.3 to 1.6 mm).

  Next, an example of a method for manufacturing the multilayer ceramic capacitor 2 according to the present embodiment will be described.

 First, as shown in FIG. 2A, a carrier sheet 20 is prepared, and a dielectric paste (green sheet paste) is applied thereon to form a green sheet 10a. The green sheet 10a constitutes the dielectric layer 10 shown in FIG. As the carrier sheet 20, for example, a PET film or the like is used, and a film coated with silicone or the like is preferable in order to improve peelability. Although the thickness of these carrier sheets 20 is not specifically limited, Preferably, it is 5-100 micrometers.

  Examples of a method for forming the green sheet 10a in FIG. 2A include a doctor blade method and a die coater method. Preferably, the green sheet 10a is formed with a thickness of about 0.5 to 30 μm, more preferably about 0.5 to 10 μm.

  The green sheet 10 a is dried after being formed on the carrier sheet 20. The drying temperature of the green sheet 10a is preferably 50 to 100 ° C., and the drying time is preferably 1 to 20 minutes. The thickness of the green sheet 10a after drying shrinks to a thickness of 5 to 25% as compared with that before drying. The thickness of the green sheet 10a after drying is preferably 3 μm or less.

  The dielectric paste is composed of an organic solvent-based paste obtained by kneading a dielectric material (ceramic powder), an organic vehicle, an inorganic additive, a plasticizer, a dispersant, and an organic solvent.

  As the dielectric material, various compounds to be complex oxides and oxides, for example, carbonates, nitrates, hydroxides, organometallic compounds, and the like are appropriately selected and used by mixing. More specifically, calcium titanate, strontium titanate, and / or barium titanate and complex oxides thereof can be mentioned. The dielectric material is usually used as a powder having an average particle size of 0.4 μm or less, preferably about 0.1 to 0.3 μm. In order to form an extremely thin green sheet 10a, it is desirable to use a powder finer than the thickness of the green sheet 10a.

 The binder used for the organic vehicle is not particularly limited, and various ordinary binders such as ethyl cellulose, polyvinyl butyral, and acrylic resin can be used. In particular, when an acrylic resin is used as the binder of the green sheet 10a, the adhesion with the internal electrode precursor layer 12a formed from the internal electrode forming paste of the present invention is improved. The acrylic resin preferably used is composed of a copolymer mainly composed of an acrylate monomer unit and a methacrylic acid ester monomer unit. The copolymerization ratio of the acrylic acid ester monomer unit and the methacrylic acid ester monomer unit can be, for example, about 10 to 30:90 to 70 by weight.

 Moreover, the acid value (mg number of KOH required to neutralize the free acid in 1 g in the acrylic resin) of the acrylic resin is 1 to 10 mgKOH / g, preferably 2 to 7 mgKOH / g. The acid value of the acrylic resin is related to the dispersion with the dielectric material, but if the acid value of the acrylic resin is outside the above range, the dispersibility of the dielectric material may deteriorate. The acid value of acrylic resin can be adjusted with the compounding quantity of an acrylate monomer unit. For example, increasing the blending amount of acrylate monomer units or methacrylic acid ester monomer units increases the acid value, and conversely decreases the acid value. The acid value of the acrylic resin can be measured by a method according to JIS-K0070.

 The organic vehicle contributes to the peelability from the support PET film by improving the strength of the dielectric sheet. It also contributes to the adhesion between the sheets at the time of lamination. The addition amount of the organic vehicle is 1 to 10 parts by weight, preferably 3 to 7 parts by weight with respect to 100 parts by weight of the dielectric material. If the amount of the organic vehicle is too small, the strength of the sheet cannot be ensured. Therefore, when the organic vehicle is peeled from the support PET film, the sheet is torn and cannot be laminated. Moreover, when there are too many organic vehicles, the heat processing in a post process becomes difficult and the malfunction which a chip | tip breaks will generate | occur | produce.

 Although it does not specifically limit as a plasticizer, A phthalic acid ester, adipic acid, phosphoric acid ester, glycols, etc. are illustrated. Preferably, dioctyl adipate (DOA), butyl butylene glycol phthalate (BPBG), didodecyl phthalate (DDP), dibutyl phthalate (DBP), dioctyl phthalate (DOP), butyl benzyl phthalate (BBP), etc. are used. It is done. Among these, it is preferable to use one or more selected from DBP, DOP, and BBP. The plasticizer is added in an amount of 0.1 to 10 parts by weight, preferably 1 to 5 parts by weight, based on 100 parts by weight of the dielectric material. By using a plasticizer, the Tg of the binder in the organic vehicle is controlled, and the peelability of the sheet from the support PET film is improved.

 Although it does not specifically limit as a dispersing agent, A polycarboxylate type dispersing agent, a nonionic dispersing agent, etc. are illustrated. In this case, a polycarboxylate-based dispersant is used. The dispersant is contained in an amount of 0.5 to 3 parts by weight, preferably 1.0 to 1.5 parts by weight, based on 100 parts by weight of the dielectric material.

 Examples of the solvent include, but are not limited to, alcohol, acetone, methyl ethyl ketone (MEK), mineral spirit, toluene, ethyl acetate, butyl acetate, butyl stearate, terpineol, butyl carbitol, and the like, preferably acetone, MEK. One or more of toluene, ethyl acetate and butyl acetate are used. The solvent is contained in a range where the nonvolatile content concentration in the dielectric paste is 20 to 50% by weight, more preferably 30 to 40% by weight. When the amount of the solvent is too small, it is difficult to apply thinly, and when it is too large, there is a disadvantage that the thickness varies due to uneven drying.

  The dielectric paste may contain an additive selected from glass frit, an insulator, and the like, if necessary. When these additives are added to the dielectric paste, the total content is desirably about 10% by mass or less.

 The dielectric paste is produced by mixing and pulverizing and dispersing. The method is not particularly limited, but as the mixing and pulverization in this embodiment, a method using ball milling and a wet jet mill is preferable. Moreover, as a dispersion process, the method of applying a high shear force is preferable.

  Next, as shown in FIG. 2B, the internal electrode precursor layer 12a is formed in a predetermined pattern on the surface of the green sheet 10a formed on the carrier sheet 20 using the internal electrode forming paste of the present invention. The internal electrode precursor layer 12a constitutes the internal electrode layer 12 shown in FIG. 1 after firing.

  The thickness of the internal electrode precursor layer 12a is preferably about 0.1 to 1.5 μm, and more preferably about 0.1 to 1.0 μm. The internal electrode precursor layer 12a may be composed of a single layer, or may be composed of two or more layers having different compositions.

  A screen printing method is employed as a method for forming the internal electrode precursor layer 12a.

  In the present embodiment, the internal electrode precursor layer 12a is formed by screen printing the internal electrode forming paste in a predetermined pattern. The internal electrode precursor layer 12a is formed from the internal electrode forming paste of the present invention described above.

  Further, as shown in FIG. 2B, before and after the formation of the internal electrode precursor layer 12a, a portion of the surface of the green sheet 10a where the pattern of the internal electrode precursor layer 12a is not formed has substantially the same thickness as the internal electrode precursor layer 12a. The blank pattern layer 14 may be formed.

  The blank pattern layer 14 is formed using a paste similar to the paste for forming the green sheet 10a. The blank pattern layer 14 can be formed by the same method as the internal electrode precursor layer 12a or the green sheet 10a.

  The internal electrode precursor layer 12a and the blank pattern layer 14 are dried as necessary. The drying temperature of the internal electrode precursor layer 12a and the blank pattern layer 14 is not particularly limited, but is preferably 70 to 120 ° C., and the drying time is preferably 1 to 10 minutes.

  Thus, the laminate unit Ua including the green sheet 10a and the internal electrode precursor layer 12a and the blank pattern layer 14 formed thereon is obtained on the carrier sheet 20. A plurality of the laminate units Ua are prepared.

  Thereafter, the carrier sheet 20 is peeled from the one laminate unit Ua. Then, the two laminate units Ua are laminated in such a positional relationship that the green sheet 10a in one laminate unit Ua is in contact with the upper surfaces of the internal electrode layer 12 and the blank pattern layer 14 in the other laminate unit Ua. By repeating such stacking a plurality of times, a stacked body is formed.

  In addition, you may form a laminated body using the laminated body unit Ub (FIG. 2C) with the structure which laminated | stacked two laminated body units Ua. Thus, the strength of the laminate unit is increased by increasing the thickness of the laminate unit. As a result, it is possible to prevent the laminate unit from being damaged in the lamination step.

  Next, a green sheet for an outer layer (a green sheet on which no electrode layer is formed) is laminated on the upper surface and / or the lower surface of the laminated body, and then final pressing is performed on the laminated body. The pressure at the time of final pressurization is preferably 10 to 200 MPa. Moreover, 40-100 degreeC is preferable for heating temperature. Thereafter, the laminate is cut into a predetermined size to form a green chip.

 The outer layer paste used for the preparation of the outer layer sheet generally has the same composition as that of the dielectric paste, and the manufacturing method thereof is substantially the same. However, in the case of the outer layer sheet, the sheet thickness is 5 to 100 μm, preferably about 5 to 50 μm, which is much thicker than the dielectric sheet. Therefore, as the paste for the outer layer, it is necessary that the non-volatile concentration in the paste is about 50 to 80% by weight. Since the paste viscosity increases due to the high non-volatile content, the movement of the small-diameter media is poor during ball milling, and the efficiency of mixing and grinding is reduced. Therefore, in the case of the outer layer paste, it is used by replacing it with a large diameter medium. The use of large-diameter media reduces the grinding effect on the dielectric powder. However, in the case of the outer layer sheet, it is not necessary to reduce the thickness and density of the dielectric sheet. It doesn't matter if used.

 The method for forming the outer layer sheet is not particularly limited as long as the layer can be formed uniformly, but in this embodiment, a die coater method is preferably employed. The outer layer sheet thickness is about 8.0 to 10.0 μm, and after laminating the outer layer sheet so that the outer layer thickness becomes 100 μm, 100 layers of the above laminate unit are laminated, and further the outer layer sheet. Are laminated to obtain a laminate. Thereafter, the laminate is cut into a predetermined size to form a green chip.

  The green chip is subjected to binder removal processing and firing processing, and heat treatment is performed to reoxidize the dielectric layer.

The binder removal treatment may be performed under normal conditions, but when a base metal such as Ni or Ni alloy is used for the electrode material powder of the internal electrode layer, it is particularly preferable to perform under the following conditions.
Temperature increase rate: 5 to 300 ° C./hour, particularly 10 to 50 ° C./hour,
Holding temperature: 200-800 ° C, especially 250-600 ° C,
Retention time: 0.5 to 20 hours, especially 1 to 10 hours,
Atmosphere: A mixed gas of humidified N ₂ and H ₂ .

The firing conditions are preferably the following conditions.
Temperature increase rate: 50 to 500 ° C./hour, particularly 200 to 300 ° C./hour,
Holding temperature: 1100-1300 ° C., in particular 1150-1250 ° C.
Retention time: 0.5-8 hours, especially 1-3 hours,
Cooling rate: 50 to 500 ° C./hour, particularly 200 to 300 ° C./hour,
Atmospheric gas: A mixed gas of humidified N ₂ and H ₂ or the like.

However, the oxygen partial pressure in the air atmosphere at the time of firing is preferably 10 ⁻² Pa or less, particularly 10 ⁻² to 10 ⁻⁸ Pa. If the above range is exceeded, the internal electrode layer tends to oxidize, and if the oxygen partial pressure is too low, the electrode material of the internal electrode layer tends to abnormally sinter and tend to break.

The heat treatment after such firing is preferably carried out at a holding temperature or maximum temperature of preferably 1000 ° C. or higher, more preferably 1000 to 1100 ° C. If the holding temperature or maximum temperature during the heat treatment is less than the above range, the dielectric material is insufficiently oxidized and the insulation resistance life tends to be shortened. In addition to a decrease, it tends to react with the dielectric substrate and shorten its lifetime. The oxygen partial pressure during the heat treatment is higher than the reducing atmosphere during firing, and is preferably 10 ⁻³ Pa to 1 Pa, more preferably 10 ⁻² Pa to 1 Pa. Below the range, it is difficult to reoxidize the dielectric layer, and when the range is exceeded, the internal electrode layer tends to oxidize. The other heat treatment conditions are preferably the following conditions.

Retention time: 0-6 hours, especially 1-4 hours,
Cooling rate: 50 to 500 ° C./hour, in particular 100 to 300 ° C./hour,
Atmospheric gas: humidified N ₂ gas or the like.

Note that to wet the N ₂ gas or mixed gas etc. may be used, for example a wetter etc.. In this case, the water temperature is preferably about 0 to 75 ° C. The binder removal treatment, firing and heat treatment may be performed continuously or independently. When performing these continuously, after removing the binder, the atmosphere is changed without cooling, and then the temperature is raised to the holding temperature at the time of baking to perform baking, and then cooled to reach the heat treatment holding temperature. Sometimes it is preferable to perform heat treatment by changing the atmosphere. On the other hand, when performing these independently, at the time of firing, after raising the temperature under N ₂ gas atmosphere with N ₂ gas or wet to the holding temperature of the binder removal processing, further continuing the heating to change the atmosphere Preferably, after cooling to the holding temperature at the time of heat treatment, it is preferable to change to N ₂ gas or a humidified N ₂ gas atmosphere and continue cooling. In the heat treatment, the temperature may be changed to a holding temperature in an N ₂ gas atmosphere, and the atmosphere may be changed, or the entire process of the heat treatment may be a humidified N ₂ gas atmosphere.

The sintered body (element body 4 in FIG. 1) thus obtained is subjected to end surface polishing by, for example, barrel polishing, sand plast, etc., and terminal electrodes 6 and 8 are formed by baking terminal electrode paste. The The firing conditions for the terminal electrode paste are preferably, for example, about 10 minutes to 1 hour at 600 to 800 ° C. in a humidified mixed gas of N ₂ and H ₂ . Then, if necessary, a pad layer is formed on the terminal electrodes 6 and 8 by plating or the like. In addition, what is necessary is just to prepare the paste for terminal electrodes like the above-mentioned paste for electrodes.

  The multilayer ceramic capacitor 2 of the present invention thus manufactured is mounted on a printed circuit board by soldering or the like and used for various electronic devices.

  The present invention is not limited to the above-described embodiment, and can be variously modified within the scope of the present invention.

  For example, in the above-described embodiment, a multilayer laminate is obtained by laminating a plurality of laminate units Ua each including the green sheet 10a and the internal electrode precursor layer 12a formed on the green sheet 10a. The formation and the formation of the internal electrode precursor layer 12a may be alternately repeated. Even in this case, the same effect as the above-described embodiment can be obtained.

  The method of the present invention is not limited to a method for manufacturing a multilayer ceramic capacitor, but can also be applied as a method for manufacturing other multilayer electronic components such as a multilayer inductor and a multilayer substrate.

(Example)
Hereinafter, the present invention will be described based on further detailed examples, but the present invention is not limited to these examples. In addition, the physical property evaluation in the following Examples and Comparative Examples was performed as follows.

"Sheet adhesion"
Two laminated units in which an internal electrode precursor layer having a thickness of 0.8 μm was formed by screen printing on a dielectric green sheet having a thickness of 0.9 μm using an acrylic resin as a binder, using an internal electrode forming paste described later. I prepared a sheet. The dielectric green sheet side of the other laminate unit was laminated on the internal electrode precursor layer of one laminate unit. Separately, an adhesive film obtained by applying a butyral resin on a support film was prepared. The dielectric green sheet side of the laminate was stuck to the butyral resin layer of the adhesive film to prepare a measurement sample. The support film side of the measurement sample was fixed to the suction table.

  Next, a lifting jig having a 1 mm square double-sided adhesive tape attached to the tip was prepared. The adhesive tape at the tip of the lifting jig was attached to the internal electrode precursor layer on the upper surface of the measurement sample, and the lifting jig was pulled up vertically. At this time, the peel force at the laminate unit interface (the interface between one dielectric green sheet and the other internal electrode precursor layer) was measured to obtain the adhesive force of the sheet.

The dielectric green sheet was prepared as follows.
First, 1.8 kg of φ2 mm ZrO ₂ media is put into a 1 liter polystyrene resin container, 200 g of dielectric powder having an average particle diameter of 0.2 μm (this is defined as 100 parts by weight), and an inorganic additive ( Ba, Ca) a copolymer comprising SiO ₃ and 4.2 parts by weight of a mixture containing Y ₂ O ₅ , MnO, V ₂ O ₅ , a butyl acrylate monomer unit and a methyl methacrylate monomer unit (Polymerization ratio = 18: 82) (Glass transition point Tg is 70 ° C., average molecular weight is 450,000, acid value is 5 mgKOH / g), 6 parts by weight of plasticizer, dispersant, solvent (MEK: toluene = 88) : 12, weight ratio) 180 parts by weight were charged. Mixed grinding was performed at a peripheral speed of 45 m / min. The resulting slurry had a nonvolatile content of about 35%. Next, this slurry was mixed and dispersed by a wet jet mill (HJP-25005 manufactured by Sugino Machine Co., Ltd.) to obtain a dielectric paste. The obtained dielectric paste was applied by a doctor blade method to obtain a dielectric green sheet having a thickness of 0.9 μm.

"Surface roughness"
An internal electrode precursor layer was formed on a dielectric green sheet using an acrylic resin as a binder. After drying at 80 ° C. for about 5 minutes, the average surface roughness Ra of the internal electrode precursor layer was measured using a surface roughness meter (Surfcoder: SE-30D, manufactured by Kosaka Laboratory Ltd.).
The average surface roughness Ra is a value (unit: μm) obtained by folding the roughness curve from the center line and dividing the area obtained by the roughness curve and the center line by the length L.

`` Lamination misalignment ''
An outer layer paste for producing an outer layer sheet was produced in the same manner as the dielectric paste. However, a φ10 mm ZrO ₂ media was used instead of the φ2 mm ZrO ₂ media during ball milling.
The obtained outer layer paste was applied by a die coater method to prepare an outer layer sheet having a thickness of 8.0 to 10.0 μm. After laminating the outer layer sheets so that the total thickness was 100 μm, 100 layers of the above-mentioned laminate unit were laminated, and 100 μm of the outer layer sheets were further laminated to obtain a laminated block.

  The resulting laminated block was divided into two at the center. The cutting direction was cut perpendicular to the longitudinal direction of the electrode pattern. The central part of the cut surface (the center of the laminated block) was observed using a microscope, and the lamination deviation of the electrodes was measured. In the case where the stacking deviation is 50 μm or more, a subsequent cutting process becomes difficult. In addition, even if it is cut, the internal electrode comes out on the end face, so that a short circuit failure may occur when the terminal electrode is attached.

"Crack occurrence rate"
The two divided multilayer blocks obtained above were cut at about 2.0 × 1.2 mm to obtain multilayer capacitor green chips. 100 multilayer capacitor green chips were fired under the following conditions to obtain multilayer capacitor chips.
Binder removal: The temperature was raised at 200 ° C./hour and held at 400 ° C. for 2 hours to perform the binder removal treatment. (The furnace atmosphere contains N ₂ or H ₂ )
Firing: The temperature was raised at 200 ° C./hour and held at 1200 ° C. for 2 hours for firing. (The furnace atmosphere contains N ₂ or H ₂ )
The appearance of the fired product was observed at 200 times using a metal microscope, and the number of cracked chips was counted to calculate the crack generation rate.

"Comprehensive evaluation"
A case where all of the following characteristics were satisfied was determined as “good”, and a case where any of the following characteristics was not satisfied was determined as “bad”.
Sheet adhesive strength: 20 N / cm ² or more Surface roughness: 0.1 μm or less Lamination: 50 μm or less Crack generation rate: less than 2%

(Example 1)
As a main binder, a raw material paste containing an ethyl cellulose resin having a number average molecular weight of about 200 to 100,000 and Ni powder having an average particle diameter of 0.2 μm was prepared. The raw material paste contains 3.5 parts by weight of ethyl cellulose resin with respect to 100 parts by weight of Ni powder.

Moreover, the following resin was prepared as an auxiliary binder.
Terpene resin A: glass transition point 38 ° C., number average molecular weight (700)
Terpene resin B: glass transition point-25 ° C., number average molecular weight (500)
Alkylphenol resin: Glass transition point 37 ° C

  20 parts by weight of the secondary binder was added to 100 parts by weight of the ethyl cellulose resin in the raw material paste, and mixing was performed with a defoaming mixer (manufactured by Ipros) to prepare an internal electrode forming paste.

  Using the obtained internal electrode forming paste, “sheet adhesive strength” was evaluated by the above method. The results are shown in Table 1.

(Comparative Example 1)
In addition, the same operation as in Example 1 was performed except that ethyl cellulose resin was used as the auxiliary binder. The results are shown in Table 1.

(Comparative Example 2)
Moreover, the same operation as Example 1 was performed except having used terpene resin C (glass transition point 23 degreeC, number average molecular weight 800) as a secondary binder. The results are shown in Table 1.

(Example 2)
The same operation as in Example 1 was performed except that the addition amounts of the terpene resin A and the alkylphenol resin as the auxiliary binder were changed as shown in Table 2. Using the obtained internal electrode forming paste, the “sheet adhesive strength”, “surface roughness”, “lamination misalignment”, and “crack generation rate” were evaluated by the above-described methods. The results are shown in Table 2.

(Comparative Example 3)
The same operation as in Example 1 was performed except that the addition amount of the ethylcellulose-based resin as the auxiliary binder was changed as shown in Table 2. Evaluation similar to Example 2 was performed using the obtained internal electrode forming paste. The results are shown in Table 2.

FIG. 1 is a schematic cross-sectional view of a multilayer ceramic capacitor dielectric particle according to an embodiment of the present invention. 2A to 2C are cross-sectional views illustrating the main part of the method for laminating the internal electrode layer and the green sheet according to an embodiment of the present invention.

Explanation of symbols

2 ... Multilayer ceramic capacitor 4 ... Capacitor body 6, 8 ... Terminal electrode 10 ... Dielectric layer 10a ... Green sheet 12 ... Internal electrode layer 12a ... Internal electrode precursor layer 14 ... Blank pattern layer 20 ... Carrier sheet (support)
Ua, Ub ... Laminate unit

Claims (12)

Electrode material powder;
Ethyl cellulose resin as the main binder;
An internal electrode forming paste for screen printing, comprising at least one resin selected from the group consisting of an alkylphenol resin and a terpene resin having a number average molecular weight of 700 or less as a secondary binder.   The internal electrode forming paste according to claim 1, wherein the number average molecular weight of the ethylcellulose-based resin is 10,000 to 200,000.   The internal electrode forming paste according to claim 1 or 2, wherein the glass transition point of the secondary binder is 50 ° C or lower.   The internal electrode forming paste according to any one of claims 1 to 3, wherein the secondary binder is a terpene resin and includes 20 to 80 parts by weight of the secondary binder with respect to 100 parts by weight of the main binder.   The internal electrode forming paste according to any one of claims 1 to 3, wherein the secondary binder is an alkylphenol resin and includes 70 to 90 parts by weight of the secondary binder with respect to 100 parts by weight of the main binder.  The internal electrode forming paste according to any one of claims 1 to 5, comprising 4.2 to 6.65 parts by weight of the main binder and the sub binder in total with respect to 100 parts by weight of the electrode material powder.   The internal electrode forming paste according to claim 1, wherein the electrode material powder contains Ni.   The internal electrode forming paste according to claim 1, wherein the electrode material powder has an average particle size of 0.05 to 0.3 μm.   A multilayer ceramic electronic component having an internal electrode layer manufactured using the internal electrode forming paste according to claim 1 and a dielectric layer.   The multilayer ceramic electronic component according to claim 9, wherein the internal electrode layer has a thickness of 1.0 μm or less. Preparing the internal electrode forming paste according to any one of claims 1 to 8,
Forming a dielectric green sheet;
A step of screen-printing the internal electrode forming paste on the dielectric green sheet to form an internal electrode precursor layer;
Laminating a plurality of dielectric green sheets having internal electrode precursor layers formed thereon to form a laminate;
Firing the laminate;
A method of manufacturing a multilayer ceramic electronic component having   The method for producing a multilayer ceramic electronic component according to claim 11, wherein the dielectric green sheet includes dielectric powder and an acrylic resin as a binder.

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