JP2010067719A - Method for manufacturing multilayer ceramic electronic component - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a multilayer ceramic electronic component capable of preventing cracks after baking by making multilayer performance excellent and suppressing a protrusion of a margin pattern end even if a binder contained in a green sheet or the margin pattern is insoluble. <P>SOLUTION: The method for manufacturing a multilayer ceramic electronic component has a step of laminating a green sheet containing a butyral resin and inner electrode patterns to obtain a laminate. In this method, the polymerization degree of the butyral resin is ≥350 but <1,000, a margin pattern is formed in the gap of the inner electrode patterns, electrode step absorbing paste has ceramic powder and a binder (ethyl cellulose and one or more selected from polymerization rosin, terpene phenol and an alicyclic group petroleum resin as a tackifier), the binder exceeding 3 pts.wt. and below 15 pts.wt. based on the ceramic powder of 100 pts.wt. is contained, and the ratio of the tackifier is 10-50 wt.% with respect to the content of the binder. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a multilayer ceramic electronic component, and more specifically, a multilayer ceramic electronic component capable of improving sheet lamination and sheet adhesion even when a green sheet is thinned. It relates to a manufacturing method.

  In a multilayer ceramic capacitor as an example of a multilayer ceramic electronic component, a ceramic green sheet is usually formed on a carrier sheet using a dielectric paste by a doctor blade method or the like, and an internal electrode paste for forming an internal electrode is formed thereon. The pattern is printed and dried to form an internal electrode pattern. Thereafter, the ceramic green sheet is peeled off from the carrier sheet and laminated to a desired number of layers.

  Here, two types of lamination methods are known, a peeling lamination method in which the ceramic green sheet is peeled off from the carrier sheet before lamination, and a thermocompression lamination method in which the carrier sheet is peeled off after lamination pressure bonding. There is no difference. Finally, this laminate is cut into chips to produce green chips. After firing these green chips, external electrodes are formed to obtain a multilayer ceramic capacitor.

  However, when the ceramic green sheets and the internal electrode patterns are alternately laminated like a multilayer ceramic capacitor, a gap where no electrode is formed is formed on the same row of the internal electrode patterns sandwiched between the ceramic green sheets. Is done. Due to this gap, a step is formed with the portion where the internal electrode pattern exists, and this causes problems such as deformation of the product chip, cracks, and delamination between sheets. In particular, when the internal electrode and dielectric layer are made thin and multi-layered for the purpose of reducing the size and increasing the capacity of the capacitor, the above-mentioned problem becomes significant and the dielectric layer breaks at the stepped portion. As a result, a short circuit failure due to a short circuit between the internal electrodes tends to occur, and the defect rate tends to increase.

  Therefore, in recent years, in order to solve various problems caused by such a step, a blank is formed by using an electrode step absorption printing paste in a gap where no internal electrode is formed following the formation of the internal electrode (internal electrode pattern layer). A technique is known in which a pattern layer is formed and laminated while the formation surface is flattened.

  With such a technique, particularly when the ceramic green sheet is made thinner (for example, 1 μm or less), it is required to pulverize the ceramic powder contained in the ceramic green sheet. As the ceramic green sheet becomes thinner, the internal electrode pattern layer and the blank pattern layer also need to be thinner. At this time, in order to match the shrinkage behavior during firing with the ceramic powder contained in the dielectric layer, it is necessary to make the ceramic powder contained in the blank pattern layer fine. When the ceramic powder is pulverized (miniaturized), the surface area of the powder increases, so that the amount of the binder is insufficient and stacking becomes difficult.

  In addition, when the internal electrode pattern layer and blank pattern layer are formed on the ceramic green sheet, the solvent in the internal electrode pattern layer and blank pattern layer printed on the ceramic green sheet swells the organic binder in the ceramic green sheet. Alternatively, the phenomenon of dissolution, the so-called “sheet attack” phenomenon becomes a problem. That is, when the “sheet attack” phenomenon occurs, wrinkles, holes, cracks, and the like occur in the ceramic green sheet, and short circuit defects and delamination phenomena (delamination) occur in the final multilayer ceramic electronic component.

  This “sheet attack” phenomenon appears more markedly as the thickness of the ceramic green sheet, the internal electrode pattern, and the blank pattern becomes thinner. In order to prevent this phenomenon, the binders are combined incompatible with each other. For example, Patent Document 1 discloses that polyvinyl butyral resin is used as the organic binder contained in the ceramic green sheet, and ethyl cellulose is used as the organic binder contained in the paste for forming the blank pattern layer. .

  Moreover, in patent document 2, in order to improve the adhesiveness of the organic binder resin contained in a green sheet, and the ethyl cellulose contained in an internal electrode paste, the internal electrode paste contains a tackifier such as rosin. Is disclosed.

  However, if the binder resin contained in the green sheet and the binder resin contained in the paste for forming the blank pattern layer are incompatible as described above, the adhesion between the green sheet and the blank pattern layer Gets worse. In such a case, the adhesiveness between the green sheet and the blank pattern layer is hardly studied, and the productivity is deteriorated.

Furthermore, a screen printing method is usually used as a method for forming the blank pattern layer. However, when the blank pattern layer is formed, the end of the formed blank pattern is lifted by the frictional force generated when the screen is separated from the blank pattern layer. And when it dried in this state, as shown in FIG. 4, the raised end part might become a saddle-shaped protrusion. When printing sheets having such protrusions are laminated, there is a problem that the electrode is bent.
JP 2005-243561 A JP-A-5-90069

  The object of the present invention is to reduce the thickness of the ceramic green sheet, and when the strength of the ceramic green sheet is weakened, the binder contained in the green sheet and the blank pattern layer is an incompatible combination. Even in this case, it is possible to improve the lamination and adhesion of the green sheet, effectively prevent cracks after firing, and effectively suppress protrusions (saddle parts) at the pattern edge after the blank pattern layer is formed. Another object of the present invention is to provide a method for manufacturing a multilayer ceramic electronic component.

  The present inventors, as a binder included in the blank pattern layer and the green sheet, when combining incompatible ethyl cellulose and butyral resin, while suppressing the protrusion (saddle portion) of the blank pattern end, In order to improve the adhesion between the blank pattern layer and the green sheet, it has been found that a specific organic substance must be used as a tackifier depending on the characteristics of the butyral resin, and the present invention has been completed.

That is, the method for manufacturing a multilayer ceramic electronic component according to the present invention includes:
A method for producing a multilayer ceramic electronic component comprising a step of alternately stacking a plurality of ceramic green sheets containing a butyral resin and a predetermined pattern of internal electrode pattern layers to obtain a green ceramic laminate,
The degree of polymerization of the butyral resin is 350 to 1000 (excluding 1000),
Before obtaining the green ceramic laminate, a blank pattern layer having substantially the same thickness as the internal electrode pattern layer is formed in a gap portion of the internal electrode pattern layer of a predetermined pattern,
The electrode level difference absorbing paste for forming the blank pattern layer has a ceramic powder and an organic binder,
The organic binder has ethyl cellulose and at least one selected from polymerized rosin, terpene phenol and alicyclic petroleum resin as a tackifier,
The organic binder is contained in an amount of more than 3 parts by weight and less than 15 parts by weight with respect to 100 parts by weight of the ceramic powder, and the content ratio of the tackifier with respect to the content of the organic binder is 10 to 50% by weight. It is characterized by.

  The butyral resin contained in the ceramic green sheet and the ethyl cellulose contained in the blank pattern layer are incompatible with each other and have poor adhesion, resulting in poor lamination during lamination. Furthermore, in order to perform thermocompression lamination using the flexibility of the green sheet, a low or medium polymerization butyral resin is used as the binder resin.

  In the present invention, the electrode level difference absorbing paste contains at least one selected from polymerized rosin, terpene phenol and alicyclic petroleum resin in the above ratio as a tackifier. These tackifiers are compatible with both butyral resin and ethyl cellulose. By including a tackifier in the electrode step absorption paste, the inherently incompatible butyral resin and ethyl cellulose Can be made compatible. As a result, the adhesiveness between the green sheet and the blank pattern layer can be improved and the sheet stackability (stackability) can be improved while effectively suppressing the protrusion (saddle portion) at the edge of the blank pattern.

  Preferably, the butyral resin is contained in an amount of more than 5 parts by weight and less than 10 parts by weight with respect to 100 parts by weight of the ceramic powder contained in the ceramic green sheet.

  Preferably, the weight average molecular weight of the ethyl cellulose is more than 75,000 and less than 250,000.

  Preferably, the ethyl cellulose has an ethoxyl group content of more than 46.1% by weight and less than 52.0% by weight.

When the tackifier is a polymerized rosin, the degree of butyralization of the butyral resin is preferably greater than 73 mol%.
When the tackifier is at least one selected from terpene phenols and alicyclic petroleum resins, the butyral degree of the butyral resin is preferably greater than 65 mol%.

  According to the present invention, by using the above-mentioned binders that are compatible with both ethyl cellulose and butyral resin, even when the green sheet and the internal electrode are thinned and multi-layered, the sheet stackability can be improved. Can be improved. Further, the protrusion (saddle portion) at the end of the blank pattern layer can be suppressed. As a result, a multilayer ceramic electronic component in which structural defects such as cracks and delamination after firing are effectively suppressed can be obtained.

  By making the characteristics of ethyl cellulose and butyral resin within the above ranges, the effects of the present invention can be further enhanced.

  The multilayer ceramic electronic component manufactured by the method according to the present invention is not particularly limited, and examples thereof include a multilayer ceramic capacitor, a multilayer ceramic inductor, a multilayer ceramic LC component, and a multilayer ceramic substrate.

Hereinafter, the present invention will be described based on embodiments shown in the drawings.
FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention.
2 (A) to 2 (C) are main part cross-sectional views showing a part of the manufacturing process of the multilayer ceramic capacitor shown in FIG.
3 (A) and 3 (B) are main part sectional views showing the continuation of the manufacturing process shown in FIGS. 2 (A) to (C),
FIG. 4 is a schematic diagram showing protrusions (saddle portions) at the end portion of the blank pattern layer according to the conventional example.

  In the present embodiment, a multilayer ceramic capacitor will be described as an example of a multilayer ceramic electronic component.

Multilayer Ceramic Capacitor As shown in FIG. 1, a multilayer ceramic capacitor 1 according to an embodiment of the present invention includes a capacitor body 10 having a configuration in which dielectric layers 2 and internal electrode layers 3 are alternately stacked. A pair of external electrodes 4, 4 are formed at both ends of the capacitor body 10 and are electrically connected to the internal electrode layers 3 arranged alternately in the body 10. The internal electrode layers 3 are laminated so that the side end faces are alternately exposed on the surfaces of the two opposite ends of the capacitor body 10. The pair of external electrodes 4, 4 are formed at both ends of the capacitor body 10 and are connected to the exposed end surfaces of the alternately arranged internal electrode layers 3 to constitute a capacitor circuit.

  There is no restriction | limiting in particular in the external shape and dimension of the capacitor | condenser body 10, and it can set suitably according to a use. The outer shape is generally a rectangular parallelepiped, and the dimensions are usually about vertical (0.4 to 5.6 mm) x horizontal (0.2 to 5.0 mm) x height (0.2 to 1.9 mm). Can do.

  The dielectric layer 2 is formed by firing a ceramic green sheet 30 shown in FIGS. 2A to 2C described later. Further, a blank pattern layer 60 shown in FIG. 2C described later also constitutes the dielectric layer 2 after firing. The material of the dielectric layer 2 is not particularly limited, and is made of a dielectric material such as calcium titanate, strontium titanate and / or barium titanate. In the present embodiment, the thickness of the dielectric layer 2 is preferably reduced to 1 μm or less.

  The internal electrode layer 3 is formed by firing an internal electrode pattern layer 40 having a predetermined pattern shown in FIGS. 2B and 2C described later. In this embodiment, the thickness of the internal electrode layer 3 is preferably 1 μm or less.

  As the material of the external electrode 4, copper, a copper alloy, nickel, a nickel alloy, or the like is usually used, but silver, a silver-palladium alloy, or the like can also be used. The thickness of the external electrode 4 is not particularly limited, but is usually about 10 to 50 μm.

Method for Manufacturing Multilayer Ceramic Capacitor Next, an example of a method for manufacturing the multilayer ceramic capacitor 1 according to this embodiment will be described.

Preparation of Dielectric Paste (1) First, a dielectric paste is prepared in order to manufacture a ceramic green sheet that will constitute the dielectric layer 2 shown in FIG. 1 after firing.

  In the present embodiment, the dielectric paste is composed of an organic solvent-based paste obtained by kneading ceramic powder (dielectric material) and an organic vehicle.

  The ceramic powder can be appropriately selected from various compounds to be complex oxides and oxides, such as carbonates, nitrates, hydroxides, organometallic compounds, and the like, and can be used as a mixture. The ceramic powder is usually used as a powder having an average particle size of 2.0 μm or less, preferably about 0.1 to 0.8 μm. In order to form a very thin ceramic green sheet, it is desirable to use a powder finer than the thickness of the ceramic green sheet.

  In this embodiment, the butyral resin as the organic binder used in the organic vehicle is a polyvinyl butyral resin. The polyvinyl butyral resin is preferably contained in an amount of more than 5 parts by weight and less than 10 parts by weight, and more preferably 6 to 9 parts by weight with respect to 100 parts by weight of the ceramic powder contained in the dielectric paste. If the content of the polyvinyl butyral resin is too small, the sheet lamination property (stackability) tends to deteriorate, and if it is too large, it is not completely removed in the binder removal step, and many cracks tend to occur in the sintered body. is there.

  In the present embodiment, the degree of polymerization of the polyvinyl butyral resin is 350 to 1000 (excluding 1000), preferably 500 to 1000 (excluding 1000). That is, a polyvinyl butyral resin having a low degree of polymerization or a medium degree of polymerization can be used. By using such a polyvinyl butyral resin, the glass transition temperature of the resin is lowered, and the flexibility of the green sheet is improved. As a result, when the thermocompression bonding is performed in the laminating process, the deformation of the green sheet is increased, and in combination with the effect of combining with the tackifier included in the electrode level difference absorbing paste described later, adhesion of the green sheet on which the electrode pattern and the blank pattern are formed Becomes easier and stackability is improved. In addition, the protrusion of the saddle portion of the blank pattern described later can be suppressed.

  Further, when a polymerized rosin is used as the tackifier contained in the electrode level difference absorbing paste for forming the blank pattern layer, the degree of butyralization of the polyvinyl butyral resin is preferably greater than 73 mol%, more preferably Is 77 mol% or more. Alternatively, when at least one selected from terpene phenol and alicyclic petroleum resin is used as the tackifier, the degree of butyralization of the polyvinyl butyral resin is preferably greater than 65 mol%.

  If the degree of butyralization is too small, the adhesiveness (stackability) between the green sheet and the blank pattern layer tends to deteriorate due to the characteristic change of the polyvinyl butyral resin. The degree of butyralization is determined by the butyralization reaction of polyvinyl alcohol and butyraldehyde, and the upper limit is 81.6 mol%. Further, the amount of residual acetyl groups in the polyvinyl butyral resin is preferably less than 6%, more preferably 3% or less.

  The organic solvent used in the organic vehicle is not particularly limited, and various alcohols, ketones, aromatics and the like may be used, and these organic solvents may be used in combination.

  Content of each component in a dielectric paste is not specifically limited, For example, a dielectric paste can be prepared so that about 30 to about 90 weight% of solvent may be included.

  In addition to dielectric powder and resin binder components as main components, additions selected from various dispersants, plasticizers, subcomponent compounds, glass frit, insulators, etc. are included in the dielectric paste. A thing may be contained. When these additives are added to the dielectric paste, the total content is desirably about 10% by weight or less.

  Examples of the plasticizer include phthalate esters such as dioctyl phthalate and benzylbutyl phthalate, adipic acid, phosphate esters, glycols, and the like. The weight ratio of the plasticizer in the paint when blending the plasticizer is not particularly limited, but is preferably 40 to 70 parts by weight with respect to 100 parts by weight of the binder. If the amount of the plasticizer is too small, the elongation and flexibility of the green sheet tend to be deteriorated. If the amount is too large, the plasticizer oozes out on the surface of the green sheet and is difficult to handle.

  In this embodiment, since a polyvinyl butyral resin is used as the organic binder in the organic vehicle, the content of the plasticizer in this case is about 25 to about 100 parts by weight with respect to 100 parts by weight of the polyvinyl butyral resin. preferable.

  The dielectric paste can be obtained by kneading the above components with a ball mill or the like to form a slurry.

Formation of ceramic green sheet (2) Next, using this dielectric paste, a wire bar coater, a doctor blade or the like, as shown in FIG. 2 (A), preferably on a carrier sheet 20 as a support, The ceramic green sheet 30 is formed with a thickness of about 1 μm or less.

  As the carrier sheet 20, for example, a PET film or the like is used, and a surface on which the ceramic green sheet 30 is formed is preferably subjected to a release treatment (coating with silicone or the like) in order to improve peelability. . Although the thickness of the carrier sheet 20 is not specifically limited, Preferably it is 5-100 micrometers.

  In this embodiment, as will be described later, the ceramic green sheets 30 on which the internal electrode pattern layer 40 and the blank pattern layer 60 are formed are laminated while being thermocompression bonded (thermocompression step). In this case, since the support is peeled after the sheets are laminated, the strength of the green sheet is not a problem at the time of lamination. Therefore, a polyvinyl butyral resin having a low degree of polymerization that affects the strength of the green sheet can be selected. Moreover, even if it is an extremely thin green sheet having a thickness of 1.0 μm or less, handling properties are not impaired.

  The ceramic green sheet 30 is dried after being formed on the carrier sheet 20. The drying temperature of the ceramic green sheet 30 is preferably 50 to 100 ° C., and the drying time is preferably 1 to 20 minutes.

  The thickness of the ceramic green sheet 30 after drying contracts by 5 to 25% from the thickness before drying. In this embodiment, the thickness of the ceramic green sheet 30 after drying is preferably 0.4 to 1 μm, and more preferably 0.4 to 0.8 μm. This is in order to meet the demand for thinner layers in recent years. If the thickness of the green sheet is too thick, depending on the thickness of the internal electrode pattern layer, the binder resin content per layer increases, and cracks tend to occur after firing.

Preparation of Internal Electrode Paste (3) Next, in order to form the internal electrode pattern layer 40 which will constitute the internal electrode layer 3 shown in FIG. 1 after firing on the surface of the ceramic green sheet, the internal electrode paste Prepare.

  The internal electrode paste is composed of an organic solvent-based paste obtained by kneading a conductor powder and an organic vehicle.

  Although it does not specifically limit as conductor powder, It is preferable to comprise at least 1 sort (s) chosen from Cu, Ni, and these alloys, More preferably, it comprises Ni or Ni alloy, and also these mixtures. .

  Ni or an Ni alloy is preferably an alloy of Ni and at least one element selected from Mn, Cr, Co, and Al, and the Ni content in the alloy is preferably 95% by weight or more. In addition, in Ni or Ni alloy, various trace components, such as P, Fe, and Mg, may be contained about 0.1 wt% or less.

  Such a conductor powder is not particularly limited in its shape, such as a spherical shape or a flake shape, and may be a mixture of these shapes. In addition, when the particle diameter of the conductor powder is usually spherical, the average particle diameter is 0.5 μm or less, preferably about 0.01 to 0.2 μm. This is to realize the thinning more surely.

  The conductor powder is preferably contained in the internal electrode paste in an amount of 30 to 60% by weight, more preferably 40 to 50% by weight.

  The organic vehicle contains an organic binder and a solvent as main components. The organic binder is not particularly limited, and examples thereof include ethyl cellulose, acrylic resin, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, polyolefin, polyurethane, polystyrene, and copolymers thereof. In this embodiment, it is preferable that ethyl cellulose is a main component. When ethyl cellulose is the main component of the organic binder, the content of ethyl cellulose in the binder is preferably 95% by weight or more, and more preferably 100% by weight. Resins that can be used in combination with ethyl cellulose, although in very small amounts, include acrylic resins and polyvinyl butyral resins.

  In this embodiment, it is preferable that the organic binder further contains a tackifier contained in an electrode level difference absorbing paste described later. Since the internal electrode paste also contains a tackifier, it is possible to improve the lamination and adhesion between the ceramic green sheet and the internal electrode pattern, and effectively prevent internal defects such as cracks after firing. be able to.

  The tackifier contained in the internal electrode paste may be the same as or different from the tackifier contained in the electrode level difference absorbing paste. Alternatively, a plurality of tackifiers may be used in combination.

  The organic binder is preferably contained in the internal electrode paste in an amount of 1 to 10 parts by weight with respect to 100 parts by weight of the conductor powder. What is necessary is just to make the content rate, average weight molecular weight, etc. of the organic binder (ethyl cellulose, tackifier, etc.) contained in an internal electrode paste the same as the ethyl cellulose and tackifier contained in the electrode level | step difference absorption paste mentioned later.

  The solvent is not particularly limited, and any known solvent such as terpineol, butyl carbitol, and kerosene can be used. In this embodiment, similarly to the electrode level difference absorbing printing paste described later, terpinyl acetate, isobornyl propionate, isobornyl butyrate, and isobornyl isobutyrete are used. It is preferable to use a mixed solvent obtained by mixing at least one selected from In the case of using such a mixed solvent, the content ratio of these solvents with respect to 100% by weight of the whole solvent may be in the same range as the electrode step absorbing print paste described later. Further, the mixing ratio may be the same as that of the electrode level difference absorbing paste described later.

  The solvent is contained in the internal electrode paste in an amount of preferably 50 to 150 parts by weight, more preferably 80 to 100 parts by weight with respect to 100 parts by weight of the conductor powder. If the amount of the solvent is too small, the paste viscosity becomes too high, and if it is too much, the paste viscosity becomes too low.

  The total content of the binder and the solvent in the organic vehicle is preferably 95% by weight or more, and more preferably 100% by weight. Examples of what can be contained in an organic vehicle together with a binder and a solvent include a plasticizer and a leveling agent.

  In the internal electrode paste, the same ceramic powder as the ceramic powder contained in the dielectric paste may be contained as a co-material. The common material has an effect of suppressing sintering of the conductor powder in the firing process. The ceramic powder used as the co-material is contained in the internal electrode paste in an amount of preferably 5 to 30 parts by weight with respect to 100 parts by weight of the conductor powder. If the amount of the co-material is too small, the effect of suppressing the sintering of the conductor powder is reduced and the sintering of the internal electrode proceeds, so that the internal electrode layer 3 after firing becomes discontinuous (discontinuous portion occurs). As a result, the apparent dielectric constant decreases. On the other hand, if the amount of the co-material is too large, the structure of the internal electrode at the time of print formation becomes discontinuous, the lineability of the internal electrode layer 3 after firing tends to deteriorate, and the apparent dielectric constant also decreases. Tend to.

  In order to improve adhesion, the internal electrode paste may contain a plasticizer. In this case, the plasticizer species and the addition amount may be the same as those of the dielectric paste.

  The internal electrode paste can be obtained by kneading the above components with a ball mill or the like to form a slurry.

Formation of Internal Electrode Pattern Layer (4) Next, as shown in FIG. 2B, an internal electrode pattern layer 40 having a predetermined pattern is formed on the surface of the ceramic green sheet 30 formed on the carrier sheet 20.

  The method for forming the internal electrode pattern layer 40 is not particularly limited as long as the layer can be formed uniformly, but in this embodiment, the screen printing method using the internal electrode paste is used.

  The thickness of the internal electrode pattern layer 40 is preferably 1.5 μm or less, more preferably 0.4 to 1 μm. If the thickness of the internal electrode pattern layer 40 is too thick, depending on the thickness of the green sheet, the binder resin content per layer increases, and cracks tend to occur after firing. Furthermore, the number of stacked layers must be reduced, and the acquired capacity is reduced, making it difficult to increase the capacity. On the other hand, if the thickness is too thin, it is difficult to form uniformly, and electrode breakage is likely to occur.

  The thickness of the internal electrode pattern layer 40 is in the above range in the current technology, but it is more preferable that the thickness is within a range in which the electrode is not interrupted.

  Thereafter, the internal electrode pattern layer 40 is dried as necessary. The drying temperature is not particularly limited, but is preferably 50 to 120 ° C., and the drying time is preferably 1 to 15 minutes.

Preparation of Electrode Step Absorbing Paste (5) Next, an electrode step absorbing paste for forming a blank pattern layer 60 formed complementary to the internal electrode pattern on the ceramic green sheet is prepared.

  In this embodiment, the electrode level difference absorbing paste is composed of an organic solvent-based paste obtained by kneading ceramic powder and an organic vehicle. The composition of the ceramic powder contained in the electrode level difference absorbing paste may be different from the composition of the ceramic powder contained in the dielectric paste, but is preferably the same composition.

  Moreover, the organic binder has ethyl cellulose and a tackifier. In order to give tackiness to the green sheet containing the polyvinyl butyral resin and the blank pattern layer containing ethyl cellulose, the tackifier is at least one selected from polymerized rosin, terpene phenol and alicyclic petroleum resin. Preferably, it is a polymerized rosin. By selecting such a tackifier, in addition to the effect as a tackifier, the protrusion (saddle portion) at the end of the blank pattern can be effectively suppressed. As a result, even when the green sheet and the internal electrode are thinned / multilayered, it is possible to improve the sheet stackability and reduce the bending of the electrode.

  When the tackifier is a polymerized rosin, the degree of butyralization of the polyvinyl butyral resin is preferably in the above range. When the tackifier is terpene phenol and an alicyclic petroleum resin, the degree of butyralization of the polyvinyl butyral resin is preferably in the above range.

  The content of the organic binder is more than 3 parts by weight and less than 15 parts by weight, preferably 6 to 12 parts by weight with respect to 100 parts by weight of the ceramic powder contained in the electrode level difference absorbing paste. Moreover, the content rate of the tackifier with respect to the total content of an organic binder is 10 to 50 weight%, More preferably, it is 30 to 50 weight%.

  If the content of the organic binder is too small, the viscosity of the electrode level difference absorbing paste tends to be low, and screen printing tends to be impossible. Moreover, when there is too much content, the adhesiveness of a sheet | seat will deteriorate and it exists in the tendency for many cracks to generate | occur | produce in a sintered compact.

  When the content ratio of the tackifier with respect to the total content of the organic binder is too small, stacking of sheets tends to be difficult. Moreover, when the content ratio is too large, the viscosity of the electrode level difference absorbing paste tends to be low, and screen printing tends to be impossible.

  The average weight molecular weight (Mw) of ethyl cellulose is preferably more than 75,000 and less than 250,000, more preferably 110000 to 230,000. If the average weight molecular weight is too small, the viscosity of the electrode level difference absorbing paste tends to be low, and screen printing tends to be impossible. On the other hand, if the average weight molecular weight is too large, the adhesiveness of the sheet is deteriorated and the sintered body tends to have many cracks.

  The content of ethoxyl groups in ethyl cellulose is preferably more than 46.1% by weight and less than 52.0% by weight, more preferably 48.0 to 49.5% by weight. When the content of the ethoxyl group is outside the above range, the adhesiveness of the sheet is deteriorated and many cracks tend to occur in the sintered body.

  As the solvent, in order to prevent the sheet attack phenomenon, a solvent that does not swell or dissolve the polyvinyl butyral resin contained in the ceramic green sheet well, that is, an incompatible solvent is preferable. Specific examples include α-terpinyl acetate, isobornyl acetate, dihydroterpinyl acetate, dihydroterpinyl methyl ether, terpinyl methyl ether, I-dihydrocarbyl acetate and the like.

  The solvent is preferably contained in the electrode level difference absorbing paste in an amount of 50 to 150 parts by weight, more preferably 80 to 100 parts by weight with respect to 100 parts by weight of the ceramic powder. If the amount of the solvent is too small, the paste viscosity becomes too high, and if it is too much, the paste viscosity becomes too low.

  In order to improve adhesion, the electrode level difference absorbing paste may contain a plasticizer. In this case, the plasticizer species and the addition amount may be the same as those of the dielectric paste.

  The electrode level difference absorbing paste can be obtained by kneading the above components with a ball mill or the like to form a slurry.

Formation of Blank Pattern Layer (6) In this embodiment, after the internal electrode pattern layer 40 having a predetermined pattern is formed on the surface of the ceramic green sheet by the printing method, or before that, the internal electrode shown in FIG. As shown in FIG. 2C, a blank pattern layer 60 having substantially the same thickness as the internal electrode pattern layer 40 is formed in the surface gap (blank pattern portion 50) of the ceramic green sheet 30 on which the pattern layer 40 is not formed. Form.

  The method for forming the blank pattern layer 60 is not particularly limited as long as the layer can be formed uniformly. In this embodiment, the screen printing method using the electrode step absorbing paste is used.

  The reason why the thickness of the blank pattern layer 60 is set to be substantially the same as that of the internal electrode pattern layer 40 is that a step is formed unless the thickness is substantially the same, and the influence increases particularly when the number of layers is increased.

  Thereafter, the internal electrode pattern layer 40 and / or the blank pattern layer 60 are dried as necessary. The drying temperature is not particularly limited, but is preferably 50 to 120 ° C., and the drying time is preferably 1 to 15 minutes.

Formation of outer layer (7) In the present embodiment, the outer layer 32 is formed to protect the ceramic green sheet 30 on which the internal electrode pattern layer 40 and the blank pattern layer 60 having a predetermined pattern are formed. In other words, a predetermined number of laminated ceramic green sheets 30 are sandwiched between the outer layers 32. The outer layer 32 has a structure in which one or more ceramic green sheets on which the internal electrode pattern layer 40 and the blank pattern layer 60 are not formed are laminated.

  Similar to the ceramic green sheet 30, the outer layer green sheet is formed on the carrier sheet 20 using the outer layer dielectric paste. As the dielectric paste for the outer layer, the dielectric paste produced as described above may be used. However, a paste in which the binder type, the amount of binder added, the degree of binder polymerization, and the like are changed may be used.

Thermocompression bonding step (8) Next, in this embodiment, as shown in FIG. 3A, an electrode layer 40 and a blank pattern layer 60 having a predetermined pattern are formed on the outer layer 32 formed on the carrier sheet 20. The ceramic green sheets 30 formed on the surface are laminated while being heated and pressurized, and the carrier sheet 20 is peeled off. And as shown in FIG.3 (B), said process is repeated to the desired number of lamination | stacking, and a green ceramic laminated body is obtained. The pressing temperature is preferably 50 to 100 ° C., and the applied pressure is preferably 5 to 25 MPa.

Green chip production, firing, etc. (9) The obtained green ceramic laminate was cut into a predetermined size to produce a green chip, which was formed through a binder removal process, a firing process, and an annealing process performed as necessary. Then, the external electrode paste is printed or transferred to the capacitor body 10 composed of a sintered body and fired to form the external electrodes 4 and 4, and the multilayer ceramic capacitor 1 is manufactured.

  Even if the ceramic green sheet is thinned by the method described in the present embodiment and the polyvinyl butyral contained in the green sheet has a low or medium degree of polymerization, an electrode step absorption paste At least one selected from a polymerized rosin, a terpene phenol, and an alicyclic petroleum resin as a tackifier contained in is compatible with the green sheet and the blank pattern layer to give tackiness. Depending on the type of tackifier, the degree of butyralization of the polyvinyl butyral resin is preferably in a specific range.

  As a result, a multilayer ceramic capacitor in which adhesion and lamination between the green sheet and the blank pattern layer are improved, and protrusions (saddle portions) at the edge of the blank pattern are suppressed, and cracks after firing are effectively prevented. 1 can be provided.

  As mentioned above, although embodiment of this invention has been described, this invention is not limited to the embodiment mentioned above at all, and can be variously modified within the range which does not deviate from the summary of this invention.

  For example, in the above-described embodiment, the multilayer ceramic capacitor is exemplified as the electronic component according to the present invention. However, the electronic component according to the present invention is not limited to the multilayer ceramic capacitor and can be applied to a multilayer ceramic substrate or the like. It is.

  In addition, a predetermined number of laminate units each formed by laminating a plurality of ceramic green sheets 30, internal electrode pattern layers 40 and blank pattern layers 60 formed by the method according to the present invention are formed, and these laminate units are laminated. By doing so, a final laminate may be fabricated.

  Furthermore, the internal electrode pattern layer and the blank pattern layer may be formed by a transfer method.

  Hereinafter, although this invention is demonstrated based on a more detailed Example, this invention is not limited to these Examples.

Example 1
Preparation of Dielectric Paste First, a dielectric paste for forming a ceramic green sheet was prepared. First, BaTiO ₃ based ceramic powder, polyvinyl butyral resin (PVB) (degree of polymerization: 800) as an organic binder, propyl alcohol, xylene, methyl ethyl ketone, 2-butoxyethyl alcohol as a solvent, diphthalic acid as a plasticizer 2-Ethylhexyl was prepared. Next, 6 parts by weight of PVB, 150 parts by weight of solvent, and plasticizer are weighed with respect to 100 parts by weight of ceramic powder, and kneaded with a zirconia ball having a diameter of 2 mm in a ball mill for 21 hours to form a slurry and dielectric A body paste was obtained. The plasticizer was added in an amount of 50 parts by weight with respect to 100 parts by weight of polyvinyl butyral.

Preparation of Internal Electrode Paste Next, an internal electrode paste for forming the internal electrode pattern layer 40 was prepared. First, Ni particles having an average particle size of 0.2 μm as a conductor powder, BaTiO ₃ ceramic powder as a co-material, ethyl cellulose, α-terpinyl acetate as a solvent, and polymerization as a tackifier Prepared rosin. And, with respect to a total of 130 parts by weight of 100 parts by weight of the conductor powder and 30 parts by weight of the co-material, 122 parts by weight of α-terpinyl acetate, 5.58 parts by weight of ethyl cellulose, and 2.22 parts by weight of Polymerized rosin was added, this was kneaded with a ball mill and three rolls, and slurried to obtain an internal electrode paste.

Preparation of Electrode Step Absorbing Paste Next, an electrode step absorbing paste for forming the blank pattern layer 60 was prepared. First, a BaTiO ₃ -based ceramic powder having the same composition as the ceramic powder contained in the dielectric paste, ethyl cellulose, α-terpinyl acetate as a solvent, and a tackifier were prepared. Then, 122 parts by weight of α-terpinyl acetate and 6 parts by weight of an organic binder are added to 100 parts by weight of the ceramic powder, and this is kneaded with a ball mill and three rolls to form a slurry to absorb the electrode level difference. A paste was obtained. The organic binder is composed of ethyl cellulose and a tackifier shown in Table 1. Moreover, the tackifier shown in Table 1 is contained at an addition ratio of 40% by weight with respect to 100% by weight of the organic binder. That is, 3.6 parts by weight of ethyl cellulose is included with respect to 100 parts by weight of the ceramic powder, and 2.4 parts by weight of the tackifier shown in Table 1 is included.

Evaluation of Electrode Step Absorbing Paste Viscosity and maximum normal stress were measured for the obtained electrode step absorbing paste. The viscosity was measured at a shear rate of 500 s ^-1 . In the measurement, a parallel plate viscometer was used. The viscosity was 2.0 Pa · s or higher. The results are shown in Table 1.

  The maximum normal stress was measured using a viscoelasticity measuring device (rheometer) capable of measuring normal stress. A pair of parallel plates (circular) having a diameter of 40 mm, a distance between the plates of 300 μm, an electrode step absorbing paste temperature of 25 ° C., and a shear rate of 1000 to 10,000 [1 / s] with respect to the electrode step absorbing paste The normal stress of the electrode level difference absorbing paste was measured. A maximum normal stress of 0.3 N or more was considered good. The results are shown in Table 1.

Production of Multilayer Ceramic Chip Capacitor Sample Next, using the dielectric paste, internal electrode paste, and electrode step absorption paste produced as described above, a multilayer ceramic chip capacitor 1 shown in FIG. 1 was further produced as follows. .

  First, a dielectric sheet was applied with a predetermined thickness on a surface of a PET film as a support subjected to a release treatment using a wire bar coater, and dried to produce a green sheet having a thickness of 0.6 μm.

  Next, a screen pattern using an internal electrode paste is formed on the obtained green sheet so that the screen pattern is a strip of 4.0 × 1.2 mm and the thickness after drying is 0.6 μm. An internal electrode pattern layer 40 (see FIG. 2B) was formed.

  Thereafter, the internal electrode pattern layer 40 and the internal electrode pattern layer 40 are substantially formed on the blank pattern portion 50 (see FIG. 2B) on the green sheet by screen printing using an electrode level difference absorbing paste. A blank pattern layer 60 (see FIG. 2C) having the same thickness was formed, and a ceramic green sheet 30 having the internal electrode pattern film 40 and the blank pattern layer 60 as shown in FIG. 2C was obtained. In this example, this ceramic green sheet 30 was used as a green sheet, and a plurality of these were prepared.

Evaluation of Blank Pattern Layer With respect to the blank pattern layer formed as described above, the height of the protrusion (saddle portion) was evaluated. The method for evaluating the height of the protrusion is not particularly limited, and may be either a contact type or a non-contact type as long as it is a method of measuring using a device that measures surface irregularities. In this embodiment, a contact-type surf coater is used, and in each pattern, the height at the flat portion (pattern central portion) and the height of the projection at the saddle portion in the pattern are measured, and the difference between the heights is measured. It calculated | required as the height of a processus | protrusion. The height of the protrusion was set to be 0.2 μm or less. The results are shown in Table 1.

  Next, a dielectric paste for forming an outer layer green sheet was prepared in the same manner as the dielectric paste prepared above except that the polymerization degree of the polyvinyl butyral resin was 1500. This dielectric paste was applied on the surface of the PET film that had been subjected to the mold release treatment to a predetermined thickness using a wire bar coater and dried to produce an outer layer green sheet having a thickness of 12 μm.

  Eight green sheets for the outer layer were prepared, and these were laminated by thermocompression bonding to form an outer layer having a thickness of 96 μm.

  On the obtained outer layer, the ceramic green sheet in which the internal electrode pattern layer and the blank pattern layer were formed was pressure-bonded under the conditions of a temperature of 75 ° C. and a pressure of 12 MPa, and the PET film was peeled off (see FIG. 3A). ). This process was repeated to stack a desired number of ceramic green sheets on which the internal electrode pattern layer and the blank pattern layer were formed (see FIG. 3B). Thereafter, the outer layer having a thickness of 96 μm was further formed by thermocompression to obtain a green ceramic laminate.

  When laminating the ceramic green sheet on which the internal electrode pattern layer and the blank pattern layer are formed, the internal electrode portion is shifted by half in the longitudinal direction of the strip shape with respect to the ceramic green sheet laminated immediately before, and the short side In the direction, positioning was performed accurately so that each electrode portion overlapped.

Evaluation of Green Ceramic Laminate Adhesive strength was measured for the obtained green ceramic laminate.

The adhesion of the green ceramic laminate was determined by converting the strength value when the laminate was pulled and peeled using an Instron 5543 tensile tester to the adhesive strength of the laminate at 1 cm square. The sheet adhesiveness was 22 N / cm ² or higher, preferably 23 N / cm ² or higher. The results are shown in Table 1.

  In addition, said evaluation was performed in the state which does not form one outer layer of a green ceramic laminated body. That is, the adhesive strength of the green sheet was evaluated not for the green sheet forming the outer layer but for the ceramic green sheet on which the internal electrode pattern layer and the blank pattern layer were formed.

Next, after the obtained green ceramic laminate was cut into a predetermined size, binder removal, firing and annealing were performed under the following conditions to obtain a sintered body.
The binder removal was performed under the conditions of a temperature rising rate: 15 ° C./hour, a holding temperature: 280 ° C., a holding time: 8 hours, and a processing atmosphere: an air atmosphere.
Firing is performed at a heating rate of 200 ° C./hour, a holding temperature of 1200 to 1380 ° C., a holding time of 2 hours, a cooling rate of 300 ° C./hour, a processing atmosphere: a reducing atmosphere (oxygen partial pressure: 10 ⁻⁶ Pa to N The mixed gas of ₂ and H ₂ was adjusted by passing water vapor).
The annealing was performed under the conditions of a holding temperature: 900 ° C., a holding time: 9 hours, a cooling rate: 300 ° C./hour, and a processing atmosphere: a humidified N ₂ gas atmosphere. A wetter was used to wet the gas during firing and annealing, and the water temperature was set to 35 ° C.

  The size of the obtained sintered body is 1.6 mm long × 0.8 mm wide × 0.8 mm high, and the thickness of the dielectric layer 2 sandwiched between the pair of internal electrode layers is about 0.6 μm. The thickness of layer 3 was 0.6 μm.

Evaluation of Sintered Body The obtained sintered body was cut and the cross section was observed to evaluate the presence or absence of cracks. This was done for 10 capacitor samples. It is preferred that no cracks are observed in all ten. The results are shown in Table 1.

As shown in Table 1, when the tackifier is polymerized rosin, terpene phenol or alicyclic petroleum resin (Sample Nos. 1 to 3), electrode step absorbing paste, protrusions in the blank pattern (saddle part) Good results have been obtained for any of the above-mentioned heights, laminates, and sintered bodies.
On the other hand, when the tackifier was gum rosin or rosin glycerin ester (Sample Nos. 4 and 5), the adhesiveness of the laminate was inferior and could not be laminated.

Example 2
A dielectric paste and an electrode step absorption paste were prepared in the same manner as in Sample No. 1 except that the addition ratio of the tackifier, the content of the organic binder, and the polymerization degree of polyvinyl butyral were set to the values shown in Table 2. Further, a green ceramic laminate and a sintered body were produced and evaluated in the same manner as in Example 1. The results are shown in Table 2.

  From Table 2, when the addition ratio of the tackifier was 0, that is, when the polymerized rosin was not added to the electrode level difference absorbing paste (Sample No. 6), it was inferior in adhesiveness, and thus could not be laminated. . Moreover, when the addition ratio of the tackifier is 5 wt% (Sample No. 7), although the adhesiveness is good, the height of the protrusions in the blank pattern cannot be improved, and cracks are also seen in the sintered body. There was a trend. On the other hand, when the addition ratio of the tackifier was larger than the range of the present invention (Sample No. 11), the viscosity of the electrode level difference absorbing paste was low and screen printing was impossible.

  Further, when the content of the organic binder was less than the range of the present invention (Sample No. 12), the viscosity of the electrode level difference absorbing paste was low and screen printing was impossible. On the other hand, when the content of the organic binder is larger than the range of the present invention (Sample No. 16), the amount of resin is increased, so that cracks occurred in the sintered body.

  Further, when the degree of polymerization of polyvinyl butyral is smaller than the range of the present invention (Sample No. 17), the function as a binder was not exhibited, and a sheet could not be formed on a PET film as a support. . On the other hand, when the degree of polymerization of polyvinyl butyral was larger than the range of the present invention (sample numbers 21 and 22), the laminate was poor in adhesiveness, and cracks were also observed in the sintered body.

Example 3
A dielectric paste and an electrode step absorption paste were prepared in the same manner as Sample No. 1 except that the weight average molecular weight of ethyl cellulose, the ethoxyl group content, and the polyvinyl butyral content were set to the values shown in Table 3. A ceramic laminate and a sintered body were produced and evaluated in the same manner as in Example 1. The results are shown in Table 3.

  From Table 3, when the weight average molecular weight of ethyl cellulose is smaller than the preferred range of the present invention (Sample No. 23), the viscosity of the electrode level difference absorbing paste was low and screen printing was impossible. On the other hand, when the weight average molecular weight of ethyl cellulose is larger than the preferred range of the present invention (Sample No. 27), the adhesion of the laminate was inferior, and cracks were also observed in the sintered body.

  In addition, when the ethoxyl group content of ethyl cellulose is outside the preferred range of the present invention (Sample Nos. 28 and 31), the properties of ethyl cellulose change, the adhesiveness of the laminate is inferior, and even in the sintered body Cracks were observed.

  Further, when the content of the polyvinyl butyral resin is smaller than the preferable range of the present invention (Sample No. 32), the content is small, so the adhesiveness of the laminate is inferior, and cracks were also observed in the sintered body. . On the other hand, when the content of the polyvinyl butyral resin is larger than the preferable range of the present invention (Sample No. 37), on the contrary, the amount of the resin is too large, so that cracks occurred in the sintered body.

Example 4
A dielectric paste and an electrode step absorption paste were prepared in the same manner as Sample No. 1 except that the tackifiers shown in Table 4 were used and the butyralization degree of the polyvinyl butyral resin was changed to the values shown in Table 4. Further, a green ceramic laminate and a sintered body were prepared and evaluated in the same manner as in Example 1. The results are shown in Table 4.

  From Table 4, when the tackifier is a polymerized rosin and the degree of butyralization of the polyvinyl butyral resin is smaller than the preferred range of the present invention (Sample No. 38), the properties of the polyvinyl butyral change, and the laminate The adhesion was inferior, and cracks were also observed in the sintered body. Similarly, when the tackifier is terpene phenol or an alicyclic petroleum resin and the degree of butyralization is outside the preferred range of the present invention (sample numbers 40 and 44), the properties of polyvinyl butyral change. Consequently, the adhesion of the laminate was inferior, and cracks were also observed in the sintered body.

FIG. 1 is a cross-sectional view of a multilayer ceramic capacitor according to an embodiment of the present invention. FIGS. 2A to 2C are cross-sectional views of relevant parts showing a part of the manufacturing process of the multilayer ceramic capacitor shown in FIG. 3 (A) and 3 (B) are cross-sectional views of the main part showing the continuation of the manufacturing process shown in FIGS. 2 (A) to 2 (C). FIG. 4 is a schematic diagram showing protrusions (saddle portions) at the end portion of the blank pattern layer according to the conventional example.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Multilayer ceramic capacitor 10 ... Capacitor body 2 ... Dielectric layer 3 ... Internal electrode layer 4 ... External electrode 20, 200 ... Carrier sheet 30, 300 ... Ceramic green sheet 32 ... Outer layer 40, 400 ... Internal electrode pattern layer 50 ... Blank pattern portion 60, 600 ... Blank pattern layer 601 ... Protrusion (saddle portion)

Claims (6)

A method for producing a multilayer ceramic electronic component comprising a step of alternately stacking a plurality of ceramic green sheets containing a butyral resin and a predetermined pattern of internal electrode pattern layers to obtain a green ceramic laminate,
The degree of polymerization of the butyral resin is 350 to 1000 (excluding 1000),
Before obtaining the green ceramic laminate, a blank pattern layer having substantially the same thickness as the internal electrode pattern layer is formed in a gap portion of the internal electrode pattern layer of a predetermined pattern,
The electrode level difference absorbing paste for forming the blank pattern layer has a ceramic powder and an organic binder,
The organic binder has ethyl cellulose and at least one selected from polymerized rosin, terpene phenol and alicyclic petroleum resin as a tackifier,
The organic binder is contained in an amount of more than 3 parts by weight and less than 15 parts by weight with respect to 100 parts by weight of the ceramic powder, and the content ratio of the tackifier with respect to the content of the organic binder is 10 to 50% by weight. A method for producing a multilayer ceramic electronic component characterized by the above.   The method for producing a multilayer ceramic electronic component according to claim 1, wherein the butyral resin is contained in an amount of more than 5 parts by weight and less than 10 parts by weight with respect to 100 parts by weight of the ceramic powder contained in the ceramic green sheet.   The method for producing a multilayer ceramic electronic component according to claim 1, wherein the weight average molecular weight of the ethyl cellulose is more than 75,000 and less than 250,000.   The method for producing a multilayer ceramic electronic component according to claim 1, wherein the ethylcellulose has an ethoxyl group content of more than 46.1% by weight and less than 52.0% by weight. When the tackifier is a polymerized rosin,
The method for producing a multilayer ceramic electronic component according to claim 1, wherein a degree of butyralization of the butyral resin is greater than 73 mol%. When the tackifier is at least one selected from terpene phenol and alicyclic petroleum resin,
The method for producing a multilayer ceramic electronic component according to claim 1, wherein a degree of butyralization of the butyral resin is greater than 65 mol%.

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