Step-absorbing paste and method for manufacturing a stacked electronic component using the step-absorbing paste

Abstract

The objective is to provide a step-absorbing paste that can improve adhesion between the step-absorbing pattern layer and the inner green sheet, as well as improve handling during operation. [Solution] A step-absorbing paste comprising a first ceramic powder, ethyl cellulose, and terpene phenol, wherein A1 is 10 to 26 parts by mass, where A1 is the total content of ethyl cellulose and terpene phenol in the step-absorbing paste when the content of the first ceramic powder in the step-absorbing paste is 100 parts by mass, the average mass molecular weight of the terpene phenol is 220 to 650, and when the total content of ethyl cellulose and the terpene phenol is 100 parts by mass, the content of terpene phenol is 30 to 67 parts by mass.

Description

[Technical Field]

[0001] The present invention relates to a paste for absorbing steps and a method for manufacturing a stacked electronic component using the paste for absorbing steps. [Background technology]

[0002] As an example of a multilayer electronic component, a multilayer ceramic capacitor can be obtained by the following manufacturing method, as shown in Patent Document 1. First, a green laminate is obtained by stacking multiple inner green sheets on which an internal electrode pattern layer is formed. Next, the green laminate is pressed and heated in a mold, cut into chip shapes, and then fired to obtain the element body. Next, an external electrode is formed on the element body to obtain a multilayer ceramic capacitor.

[0003] In this case, the inner green sheet does not typically have an internal electrode pattern layer formed across its entire surface; instead, gaps are formed in the internal electrode pattern layer.

[0004] However, when lamination is performed with gaps created by the internal electrode pattern layer, the force applied to the inner green sheet by pressing becomes uneven due to the presence of these gaps. As a result, unintended deformations such as bending of the inner green sheet in the gap areas and changes in the thickness of the volume-forming areas become problematic.

[0005] Therefore, a step-absorbing pattern layer is sometimes formed using a step-absorbing paste to fill the gaps in the internal electrode pattern layer.

[0006] Incidentally, as multilayer ceramic capacitors become thinner, the strength of the inner green sheet improves, but this tends to reduce the adhesion between the step absorption pattern layer and the inner green sheet.

[0007] One way to improve this trend is to give the step-absorbing pattern layer high adhesive strength. However, when high adhesive strength is given to the step-absorbing pattern layer, this tends to reduce handling performance during work, such as causing unexpected adhesion. [Prior art documents] [Patent Documents]

[0008] [Patent Document 1] Japanese Patent Publication No. 2000-133547 [Overview of the Initiative] [Problems that the invention aims to solve]

[0009] The present invention has been made in view of the above circumstances and aims to provide a step-absorbing paste that can improve the adhesion between the step-absorbing pattern layer and the inner green sheet, as well as improve handling during operation, and a method for manufacturing a laminated electronic component using the step-absorbing paste. [Means for solving the problem]

[0010] The step-absorbing paste according to the present invention is a step-absorbing paste comprising a first ceramic powder, ethyl cellulose, and terpene phenol, A1 is 10 to 26 parts by mass, A1 is the total content of ethylcellulose and terpene phenol in the step-absorbing paste when the content of the first ceramic powder in the step-absorbing paste is 100 parts by mass. The average mass molecular weight of the terpene phenol is 220 to 650. A step-absorbing paste wherein, when the total content of the ethylcellulose and the terpene phenol is 100 parts by mass, the content of the terpene phenol is 30 parts by mass to 67 parts by mass.

[0011] According to the paste for step absorption according to the present invention, the adhesion between the step absorption pattern layer and the inner green sheet can be improved, and the handling property during work can also be improved.

[0012] The manufacturing method of the multilayer electronic component according to the present invention is a manufacturing method of a multilayer electronic component having a step of alternately laminating an inner green sheet and an internal electrode pattern layer to obtain a green laminate, a step absorption pattern layer is formed in the gap of the internal electrode pattern layer, the inner green sheet is formed using a paste for inner ceramic, the paste for inner ceramic contains a second ceramic powder and a butyral resin, the step absorption pattern layer is formed using a paste for step absorption, the paste for step absorption has a first ceramic powder, ethyl cellulose, and terpene phenol, A1 is 10 parts by mass to 26 parts by mass, the A1 is the total content of the ethyl cellulose and the terpene phenol in the paste for step absorption when the content of the first ceramic powder in the paste for step absorption is 100 parts by mass, the average mass molecular weight of the terpene phenol is 220 to 650, when the total content of the ethyl cellulose and the terpene phenol is 100 parts by mass, the content of the terpene phenol is 30 parts by mass to 67 parts by mass.

[0013] According to the multilayer electronic component according to the present invention, the adhesion between the step absorption pattern layer and the inner green sheet can be improved, and the handling property during work can also be improved.

[0014] Preferably, the components of the first ceramic powder and the second ceramic powder are substantially the same.

[0015] Preferably, A2 is more than 10 parts by mass and 20 parts by mass or less, wherein A2 is the content of the butyral resin in the inner ceramic paste when the content of the second ceramic powder in the inner ceramic paste is 100 parts by mass, and A1 is not less than A2.

Brief Description of Drawings

[0016] [Figure 1A] FIG. 1A is a cross-sectional view showing a multilayer ceramic capacitor according to an embodiment of the present invention. [Figure 1B] FIG. 1B is a cross-sectional view of the multilayer ceramic capacitor taken along line IB-IB in FIG. 1A. [Figure 2A] FIG. 2A is a cross-sectional view of a main part showing a part of the manufacturing process of the multilayer ceramic capacitor shown in FIGS. 1A and 1B. [Figure 2B] FIG. 2B is a cross-sectional view of a main part showing the continuation of the manufacturing process shown in FIG. 2A. [Figure 2C] FIG. 2C is a cross-sectional view of a main part showing the continuation of the manufacturing process shown in FIG. 2B. [Figure 3A] FIG. 3A is a cross-sectional view of a main part showing the continuation of the manufacturing process shown in FIG. 2C. [Figure 3B] FIG. 3B is a cross-sectional view of a main part showing the continuation of the manufacturing process shown in FIG. 3A. [Figure 4A] FIG. 4A is a cross-sectional view of a main part showing the continuation of the manufacturing process shown in FIG. 3B. [Figure 4B] FIG. 4B is a cross-sectional view of a main part showing the continuation of the manufacturing process shown in FIG. 3B.

Embodiments for Carrying Out the Invention

[0017] Hereinafter, the present invention will be described based on the embodiments shown in the drawings. In this embodiment, a multilayer ceramic capacitor will be exemplified and described as a multilayer electronic component.

[0018] Multilayer ceramic capacitor As shown in Figures 1A and 1B, a multilayer ceramic capacitor 1 according to one embodiment of the present invention has an element body 10. The element body 10 has an interior region 10a, an exterior region 10b, and a margin region 10c.

[0019] The interior region 10a has an inner dielectric layer 2 (inner ceramic layer 2) and internal electrode layers 3a and 3b that are substantially parallel to a plane containing the X and Y axes, and the inner dielectric layer 2 and the internal electrode layers 3a and 3b are stacked alternately in the Z-axis direction. Furthermore, the ends of the internal electrode layers 3a and 3b in the X-axis direction are stacked alternately on the surface of two opposing end faces (planes parallel to the ZY plane) in the X-axis direction of the element body 10.

[0020] A pair of external electrodes 4a and 4b are formed on both ends of the element body 10 in the X-axis direction, and these electrodes are electrically connected to the internal electrode layers 3a and 3b which are alternately arranged inside the element body 10. The external electrodes 4a and 4b are connected to the exposed ends of the alternately arranged internal electrode layers 3 to form a capacitor circuit.

[0021] The outer region 10b is located outside the inner region 10a in the stacking direction (Z-axis direction). The outer region 10b is composed of an outer dielectric layer (outer ceramic layer). The outer region 10b may be a single-layer structure consisting of only one outer dielectric layer, or it may be a stacked structure in which multiple outer dielectric layers are stacked.

[0022] The margin region 10c is provided to the side of the interior region 10a. Specifically, as shown in Figure 1B, the margin region 10c is defined as the section along the Y-axis direction of the element body 10, from the plane parallel to the ZX plane that includes the Y-axis ends of the internal electrode layers 3a and 3b, to the Y-axis end face of the element body 10 (the plane parallel to the ZX plane).

[0023] Here, the X, Y, and Z axes are perpendicular to each other.

[0024] Furthermore, "inside" refers to the side closer to the center of the multilayer ceramic capacitor 1, while "outside" refers to the side further away from the center of the multilayer ceramic capacitor 1.

[0025] Furthermore, "substantially parallel" means that most parts are parallel, but there may be some non-parallel parts, and the inner dielectric layer 2 and the inner electrode layers 3a and 3b may have some irregularities or be tilted.

[0026] There are no particular restrictions on the external shape or dimensions of the element body 10, and they can be set as appropriate depending on the application. Typically, the external shape is roughly rectangular, and the dimensions can be approximately L0 (0.4 mm to 5.6 mm) × W0 (0.2 mm to 5.0 mm) × T0 (0.2 mm to 1.9 mm).

[0027] The inner dielectric layer 2 is formed by firing the inner green sheet 30 shown in Figures 2A to 2C, which will be described later. The step absorption pattern layer 60 shown in Figure 2C, which will also be described later, will also constitute the inner dielectric layer 2 after firing.

[0028] The main component of the inner dielectric layer 2 is not particularly limited; for example, a compound represented by the general formula ABO3 can be used.

[0029] Here, the main component of the inner dielectric layer 2 is the component that accounts for 80 parts by mass or more when the inner dielectric layer 2 is considered to be 100 parts by mass, and preferably the component that accounts for 90 parts by mass or more.

[0030] Furthermore, the main component of the inner dielectric layer 2 is the component that makes up the second ceramic powder after firing. The second ceramic powder is contained in the inner green sheet 30.

[0031] Specific examples of compounds represented by the general formula ABO3 include {(Ba 1-x-y Ca x Sr y )O} u (Ti 1-z Zr z ) vExamples include compounds represented by O3. Note that u, v, x, y, and z are all within any range, but are preferably within the following ranges.

[0032] In the above formula, x is preferably 0 ≤ x ≤ 0.1, and more preferably 0 ≤ x ≤ 0.05. By setting x within the above range, the relative permittivity can be improved. Furthermore, in this embodiment, Ca does not necessarily have to be included. That is, x may be 0.

[0033] In the above formula, y is preferably 0 ≤ y ≤ 0.1, and more preferably 0 ≤ y ≤ 0.05. By setting y within the above range, the relative permittivity can be improved. Furthermore, in this embodiment, Sr does not necessarily have to be included. That is, y may be 0.

[0034] In the above formula, z is preferably 0 ≤ z ≤ 0.3, and more preferably 0 ≤ z ≤ 0.15. By setting z within the above range, the relative permittivity can be improved. Furthermore, in this embodiment, Zr does not necessarily have to be included. That is, z may be 0.

[0035] In the above formula, it is preferable that u and v satisfy the relationship u / v = 0.9 to 1.2.

[0036] Furthermore, it is preferable that the main component of the inner dielectric layer 2 is barium titanate. That is, it is preferable that x=y=z=0.

[0037] The inner dielectric layer 2 may contain elements such as Ba, Si, Mg, Mn, V, Zr, and rare earth elements as minor components.

[0038] The thickness of the inner dielectric layer 2 is preferably reduced to 1 μm or less.

[0039] The internal electrode layers 3a and 3b are formed by firing an internal electrode pattern layer 40 with a predetermined pattern as shown in Figures 2B and 2C, which will be described later. The internal electrode pattern layer 40 contains conductive powder.

[0040] The conductive powder is not particularly limited, but it is preferably composed of at least one selected from Cu, Ni, and their alloys, and more preferably Ni or a Ni alloy, or even a mixture thereof.

[0041] Preferably, the Ni or Ni alloy is an alloy of Ni with at least one element selected from Mn, Cr, Co, and Al, and the Ni content in the alloy is preferably 95% by mass or more. In addition, various trace components such as P, Fe, and Mg may be contained in the Ni or Ni alloy at a concentration of about 0.1% by mass or less.

[0042] The thickness of the internal electrode layers 3a and 3b is preferably reduced to 1 μm or less.

[0043] The materials used for the external electrodes 4a and 4b are typically copper, copper alloys, nickel, or nickel alloys, but silver or silver-palladium alloys can also be used. The thickness of the external electrodes 4a and 4b is not particularly limited, but is usually around 10 μm to 50 μm.

[0044] Manufacturing method for multilayer ceramic capacitors Next, an example of a manufacturing method for the multilayer ceramic capacitor 1 according to this embodiment will be described.

[0045] To manufacture the inner green sheet 30, which will constitute the inner dielectric layer 2 shown in Figures 1A and 1B after firing, an inner dielectric paste (inner ceramic paste) is prepared.

[0046] In this embodiment, the paste for the inner dielectric is composed of an organic solvent-based paste obtained by kneading a second ceramic powder (dielectric material) and a second organic vehicle, the second organic vehicle containing butyral resin.

[0047] As the second ceramic powder, various compounds that form composite oxides or oxides of the elements constituting the second ceramic powder, such as carbonates, nitrates, hydroxides, and organometallic compounds, can be appropriately selected and mixed for use.

[0048] The second ceramic powder is typically used as a powder with an average particle size of 2.0 μm or less, preferably around 0.1 μm to 0.8 μm. In order to form an extremely thin inner green sheet 30, it is desirable to use a powder finer than the thickness of the inner green sheet 30 as the second ceramic powder.

[0049] The second organic vehicle contains a butyral resin as a binder. Examples of butyral resins include polyvinyl butyral resin.

[0050] When the content of the second ceramic powder in the inner dielectric paste is 100 parts by mass, and the content of the butyral resin in the inner dielectric paste is A2, then A2 is preferably more than 10 parts by mass and 20 parts by mass or less, and more preferably 11 to 15 parts by mass.

[0051] By keeping the butyral resin content within the above range, the following effects (1) to (3) can be obtained.

[0052] (1) The adhesion between the step-absorbing pattern layer 60 and the inner green sheet 30 can be further improved.

[0053] (2) The amount of shrinkage of the inner green sheet 30 during the binder removal process can be minimized, and the occurrence of cracks in the element body 10 caused by the shrinkage of the inner green sheet 30 can be further reduced.

[0054] (3) In the binder removal process, the butyral resin tends to be completely removed, which further suppresses cracking of the element body 10.

[0055] In this embodiment, the degree of polymerization of the polyvinyl butyral resin is preferably 1000 to 2400, more preferably 1000 to 2400 (excluding 1000), and even more preferably 1700 to 2400. In other words, a polyvinyl butyral resin with a high degree of polymerization can be used.

[0056] Using such polyvinyl butyral resin improves the strength of the inner green sheet 30. However, in this case, the adhesion between the step-absorbing pattern layer 60 and the inner green sheet 30 may decrease.

[0057] In contrast, in this embodiment, by forming a step-absorbing pattern layer 60 on the inner green sheet 30 using a predetermined step-absorbing paste described later, it is possible to sufficiently maintain the strength of the inner green sheet 30 while significantly improving the adhesion between the step-absorbing pattern layer 60 and the inner green sheet 30.

[0058] Furthermore, in this embodiment, the degree of butyralization of the polyvinyl butyral resin contained in the inner dielectric paste is preferably more than 55 mol% and less than 69 mol%, more preferably 60 mol% to 65 mol%. By having the degree of butyralization within the above range, the adhesion between the step absorption pattern layer 60 and the inner green sheet 30 can be further improved.

[0059] The second organic vehicle may contain a second organic solvent in addition to the butyral resin. The second organic solvent is not particularly limited, and various alcohols, ketones, aromatics, etc., can be used, and these second organic solvents may be mixed and used. The content of the second organic solvent in the inner dielectric paste is not particularly limited, but can be, for example, 30% to 90% by mass.

[0060] In addition to the second ceramic powder, butyral resin, and second organic solvent as the main components, the paste for the inner dielectric may contain, as needed, additives selected from various dispersants, plasticizers, minor component compounds, glass frit, insulators, etc. When these additives are added to the paste for the inner dielectric, it is desirable that the total content of these additives be 10% by mass or less.

[0061] Examples of plasticizers included in the inner dielectric paste include phthalate esters such as dioctyl phthalate and benzyl butyl phthalate, adipic acid, phosphoric acid esters, and glycols. The content of plasticizer in the inner dielectric paste is not particularly limited, but is preferably 5 to 100 parts by mass, and more preferably 5 to 40 parts by mass, per 100 parts by mass of butyral resin. By keeping the plasticizer within the above range, the elongation and flexibility of the inner green sheet 30 are improved, and the plasticizer is less likely to seep out onto the surface of the inner green sheet 30, making it easy to handle.

[0062] Furthermore, the paste for the inner dielectric preferably contains substantially no terpene phenols, and is preferably 5 parts by mass or less, and more preferably 3 parts by mass or less, per 100 parts by mass of butyral resin.

[0063] The paste for the inner dielectric is obtained by first dispersing the second ceramic powder in a second organic solvent using a bead mill, and then kneading the second organic vehicle.

[0064] Next, using this inner dielectric paste, an inner green sheet 30 is formed on the carrier sheet 20 as a support, preferably with a thickness of about 1 μm or less, using a wire bar coater or doctor blade, as shown in Figure 2A.

[0065] For the carrier sheet 20, for example, a PET film is used, and to improve release properties, it is preferable that the surface on which the inner green sheet 30 is formed is treated with a release agent (such as a silicone coating). The thickness of the carrier sheet 20 is not particularly limited, but is preferably 5 μm to 100 μm.

[0066] The inner green sheet 30 is dried after it is formed on the carrier sheet 20. The drying temperature of the inner green sheet 30 is preferably 50°C to 100°C, and the drying time is preferably 1 minute to 20 minutes.

[0067] The thickness of the inner green sheet 30 after drying shrinks by 5% to 25% from its thickness before drying. In this embodiment, the inner green sheet 30 is formed to have a thickness of preferably 0.4 μm to 1 μm, and more preferably 0.4 μm to 0.8 μm, in order to meet the demand for thinner layers that has been desired in recent years.

[0068] Next, an internal electrode paste is prepared to form the internal electrode pattern layer 40, which will constitute the internal electrode layers 3a and 3b shown in Figures 1A and 1B after firing, on the surface of the inner green sheet 30.

[0069] The paste for the internal electrodes consists of an organic solvent-based paste obtained by kneading conductive powder and a third organic vehicle.

[0070] Such conductive powders are not particularly limited in shape, such as spherical or flake-shaped, and may also be mixtures of these shapes. Furthermore, the particle size of the conductive powder is usually such that, in the case of spherical particles, the average particle size is 0.5 μm or less, preferably around 0.01 μm to 0.2 μm. This is to ensure even more reliable thin-layer formation.

[0071] The conductive powder is preferably contained in the internal electrode paste at an amount of 30% to 60% by mass, more preferably 45% to 55% by mass.

[0072] The third organic vehicle mainly contains a third organic binder and a third organic solvent. The third organic binder is not particularly limited, but examples include ethylcellulose, acrylic resin, polyvinyl butyral, polyvinyl acetal, polyvinyl alcohol, polyolefin, polyurethane, polystyrene, or copolymers thereof, and preferably mainly contains ethylcellulose.

[0073] When ethylcellulose is the main component of the third organic binder, the ethylcellulose content in the third organic binder is preferably 95% by mass or more, and more preferably 100% by mass. Resins that can be used in combination with ethylcellulose, although in very small amounts, include acrylic resins and polyvinyl butyral resins.

[0074] The paste for the internal electrodes preferably also contains terpene phenol, which is included in the step-absorbing paste described later, as a tackifier. Including terpene phenol in the paste for the internal electrodes improves the adhesion between the inner green sheet 30 and the internal electrode pattern layer 40, and effectively prevents internal defects such as cracks after firing.

[0075] The third organic binder and terpene phenol are preferably included in the internal electrode paste in an amount of 1 to 10 parts by mass per 100 parts by mass of conductive powder. The content ratio and average mass molecular weight of the third organic binder and terpene phenol in the internal electrode paste may be the same as those of the ethyl cellulose and terpene phenol included in the step absorption paste described later.

[0076] The third organic solvent included in the paste for internal electrodes is not particularly limited, but any known solvent such as terpineol, butyl carbitol, or kerosene can be used. For the third organic solvent, it is preferable to use a mixed solvent obtained by mixing terpinyl acetate with one or more substances selected from isobonylpropionate, isobonylbutyrate, and isobonylisobutyrate, similar to the first organic solvent included in the step-absorbing paste described later. When using such a mixed solvent, the composition of the third organic solvent may be the same as that of the first organic solvent described later.

[0077] The content of the third organic solvent in the paste for the internal electrodes is preferably 50 to 150 parts by mass, more preferably 60 to 100 parts by mass, per 100 parts by mass of conductive powder.

[0078] The total content of the above-mentioned third organic binder, terpene phenol, and third organic solvent in the third organic vehicle is preferably 95% by mass or more, and more preferably 100% by mass. Substances that can be included in the third organic vehicle together with the third organic binder, terpene phenol, and third organic solvent include plasticizers and leveling agents.

[0079] The paste for the internal electrodes may contain ceramic powder as a co-material. The co-material has the effect of suppressing the sintering of the conductive powder during the firing process. The ceramic powder used as a co-material is preferably included in the paste for the internal electrodes in an amount of 5 to 30 parts by mass per 100 parts by mass of conductive powder. By keeping the amount of co-material within the above range, the sintering suppression effect of the conductive powder can be achieved while suppressing electrode breaks in the internal electrode layers 3a and 3b after firing.

[0080] The paste for the internal electrodes is obtained by dispersing conductive powder and co-materials in a bead mill or the like, and then kneading these together with a third organic vehicle.

[0081] Next, as shown in Figure 2B, an internal electrode pattern layer 40 with a predetermined pattern is formed on the surface of the inner green sheet 30 formed on the carrier sheet 20.

[0082] The method for forming the internal electrode pattern layer 40 is not particularly limited as long as it can form the layer uniformly, but in this embodiment, a screen printing method using the internal electrode paste described above is used.

[0083] The thickness of the internal electrode pattern layer 40 is preferably 1.5 μm or less, more preferably 0.4 μm to 1.0 μm. The thickness of the internal electrode pattern layer 40 should be as thin as possible without interruption to the internal electrode layers 3a and 3b.

[0084] Subsequently, the internal electrode pattern layer 40 is dried as needed. The drying temperature is not particularly limited, but is preferably 50°C to 120°C, and the drying time is preferably 1 to 15 minutes.

[0085] Next, a step-absorbing paste is prepared on the inner green sheet 30 to form a step-absorbing pattern layer 60 that is formed complementary to the internal electrode pattern layer 40.

[0086] In this embodiment, the step-absorbing paste is composed of an organic solvent-based paste obtained by kneading a first ceramic powder and a first organic vehicle, the first organic vehicle containing ethylcellulose and terpene phenol. The composition of the first ceramic powder contained in the step-absorbing paste may differ from the composition of the second ceramic powder contained in the inner dielectric paste described above, but it is preferable that they be substantially the same.

[0087] When the content of the first ceramic powder in the step-absorbing paste is 100 parts by mass, and the total content of ethylcellulose and terpene phenol in the step-absorbing paste is A1, then A1 is 10 to 26 parts by mass, preferably 12 to 22 parts by mass, and more preferably 13 to 19 parts by mass.

[0088] As long as A1 is within the above range, the following effects (1) to (3) can be obtained.

[0089] (1) The adhesion between the step-absorbing pattern layer 60 and the inner green sheet 30 can be improved.

[0090] (2) The amount of shrinkage of the step absorption pattern layer 60 during the binder removal process can be minimized, and the occurrence of cracks in the element body 10 caused by the shrinkage of the step absorption pattern layer 60 can be reduced.

[0091] (3) In the binder removal process, ethylcellulose and terpene phenol tend to be completely removed, which can suppress cracking of the element body 10.

[0092] Furthermore, it is preferable that A1 is greater than or equal to A2, and more preferably that A1 is 1.1 times or more than A2.

[0093] Furthermore, when the total content of ethylcellulose and terpene phenol is 100 parts by mass, the content of terpene phenol is 30 to 67 parts by mass, preferably 40 to 60 parts by mass, and more preferably 50 to 60 parts by mass.

[0094] By keeping the terpene phenol content within the above range relative to the ethyl cellulose and terpene phenol content, screen printing is made easier, and the adhesion between the step-absorbing pattern layer 60 and the inner green sheet 30 can be improved.

[0095] The average mass molecular weight of ethylcellulose is preferably more than 40,000 and less than 250,000, more preferably between 50,000 and 150,000. Having the average mass molecular weight within the above range makes screen printing easier and improves the adhesion between the step absorption pattern layer 60 and the inner green sheet 30.

[0096] Furthermore, the ethoxyl group content of ethylcellulose is preferably more than 46.1% by mass and less than 52.0% by mass, and more preferably 48.0% to 49.5% by mass. By having the ethoxyl group content within the above range, the adhesion between the step absorption pattern layer 60 and the inner green sheet 30 can be further improved.

[0097] The average mass molecular weight of terpene phenols is 220 to 650, preferably 220 to 400, and more preferably 220 to 300.

[0098] As the first organic solvent, in order to prevent the sheet attack phenomenon, it is preferable to use one that does not swell or dissolve the butyral resin contained in the inner green sheet 30, i.e., one that is miscible. Specifically, examples include α-terpinyl acetate, isovonyl acetate, dihydroterpinyl acetate, dihydroterpinyl methyl ether, terpinyl methyl ether, and I-dihydrocarbyl acetate.

[0099] The first organic solvent is preferably contained in the step-absorbing paste in an amount of 50 to 150 parts by mass, more preferably 80 to 100 parts by mass, per 100 parts by mass of the first ceramic powder.

[0100] The step-absorbing paste may contain a plasticizer, but it is preferable that it is substantially free of plasticizers. Specifically, when the total content of ethylcellulose and terpene phenol in the step-absorbing paste is 100 parts by mass, the content of the plasticizer is preferably 10 parts by mass or less, and more preferably 3 parts by mass or less.

[0101] Because it contains virtually no plasticizer, the adhesive strength of the step-absorbing paste can be kept low at around 35°C before heating, which suppresses the occurrence of unintended adhesion in processes other than the lamination process, as well as problems such as adhesion to the mold of the lamination machine, and also suppresses the seepage of plasticizer onto the surface over time.

[0102] In this embodiment, the term "plasticizer" refers to a low-molecular-weight compound that imparts plasticity. Specific examples of such substances include phthalate esters such as dioctyl phthalate and benzyl butyl phthalate, adipic acid, phosphate esters, and glycols.

[0103] The paste for absorbing uneven surfaces may contain a dispersant.

[0104] The step-absorbing paste is obtained by dispersing a first ceramic powder in a first organic solvent using a process such as a bead mill, and then kneading it with a first organic vehicle.

[0105] In this embodiment, after forming an internal electrode pattern layer 40 of a predetermined pattern on the surface of the inner green sheet 30 by printing, a step absorption pattern layer 60 with substantially the same thickness as the internal electrode pattern layer 40 is formed in the surface gap (blank pattern portion 50) of the inner green sheet 30 where the internal electrode pattern layer 40 is not formed, as shown in Figure 2B, as shown in Figure 2C. Specifically, the thickness of the step absorption pattern layer 60 is preferably 70% to 110%, more preferably 90% to 105%, of the internal electrode pattern layer 40. By having the thickness of the step absorption pattern layer 60 fall within the above range, variations in the thickness of the inner dielectric layer 2 can be suppressed, and the bell-shaped deformation of the element body 10, which will be described later, can be suppressed.

[0106] Furthermore, a step-absorbing pattern layer 60 may be formed on the surface of the inner green sheet 30 before forming the internal electrode pattern layer 40 of a predetermined pattern on the surface of the inner green sheet 30 by printing.

[0107] The method for forming the step-absorbing pattern layer 60 is not particularly limited as long as it can form the layer uniformly, but in this embodiment, a screen printing method using the above-mentioned step-absorbing paste is used.

[0108] The reason for making the thickness of the step absorption pattern layer 60 substantially the same as that of the internal electrode pattern layer 40 is that by making them substantially the same thickness, steps are less likely to occur, and the effect of steps can be reduced, especially when multiple layers are constructed.

[0109] Subsequently, the internal electrode pattern layer 40 and / or step absorption pattern layer 60 are dried as needed. The drying temperature is not particularly limited, but is preferably 50°C to 120°C, and the drying time is preferably 1 to 15 minutes.

[0110] In this way, the inner green sheets 30 stacked in a predetermined number form the interior green laminate 110a. Outer green laminates 110b are formed at both ends of the interior green laminate 110a in the stacking direction. That is, the interior green laminate 110a is sandwiched between the outer green laminates 110b. The outer green laminate 110b has a structure in which one or more outer green sheets are stacked, and the internal electrode pattern layer 40 and the step absorption pattern layer 60 are not formed thereon.

[0111] The outer green sheet constituting the outer green laminate 110b is formed on the carrier sheet 20 using an outer dielectric paste, similar to the inner green sheet 30. The inner dielectric paste prepared above may be used as the outer dielectric paste, but a paste with different binder types, binder addition amounts, and binder polymerization degrees may also be used.

[0112] Next, the green laminate 110, including the interior green laminate 110a and the exterior green laminate 110b, is pressurized and heated in a mold. Preferably, the temperature at this time is 50°C to 100°C and the pressure is 5 MPa to 25 MPa.

[0113] As shown in Figure 4A, in the ZX section, the step absorption pattern layers 60 of the inner green sheets 30 adjacent in the Z-axis direction are formed so as not to overlap in the Z-axis direction.

[0114] In contrast, as shown in Figure 3B, in the ZY cross-section, the step absorption pattern layers 60 of the inner green sheets 30 adjacent in the Z-axis direction are formed to overlap in the Z-axis direction.

[0115] The step-absorbing pattern layer 60 in the ZY cross-section, and the inner green sheet 30 and / or outer region green laminate 10b in the area adjacent to the step-absorbing pattern layer 60 in the Z-axis direction, constitute a margin region green laminate 110c that becomes a margin region 10c after firing.

[0116] As shown in Figures 4A and 4B, the obtained green laminate 110 is cut to predetermined dimensions along, for example, cut surfaces C1 and C2, and then peeled off the substrate to form green chips.

[0117] Here, as shown in Figure 4A, in the ZX section, the cutting surface C1 is determined such that the internal electrode pattern layer 40 and the step absorption pattern layer 60 are alternately cut along the Z-axis direction, with the inner green sheet 30 in between.

[0118] Furthermore, as shown in Figure 4B, the cross-section C2 is determined such that in the YZ section, only the inner green sheet 30, the outer green sheet 110b, and the step absorption pattern layer 60 are cut along the Z axis.

[0119] By obtaining a green chip using this cutting method, the internal electrode pattern layer 40 of the green chip is exposed on one cut surface C1 but not on the other cut surface C1.

[0120] Furthermore, the cross-section C2 of the green chip can be used to form a margin region green laminate 110c.

[0121] Please note that Figures 4A and 4B are only schematic cross-sectional views, and the number of layers, dimensions, etc., may differ from the actual structure.

[0122] The green chips are solidified by solidification drying, which removes the plasticizer. After solidification drying, the green chips are placed in a barrel container along with media and polishing fluid, and barrel polished using a horizontal centrifugal barrel machine or the like. After barrel polishing, the green chips are washed with water and dried. After drying, the green chips are subjected to a debindering process, a firing process, and an annealing process as needed, to obtain the element body 10 (sintered body) shown in Figures 1A and 1B.

[0123] Next, the external electrode paste is printed or transferred onto the element body 10 and fired to form the external electrodes 4a and 4b, thereby manufacturing the multilayer ceramic capacitor 1.

[0124] If a step-absorbing pattern layer is not formed, the thickness of the inner dielectric layer may vary, and the element body may deform into a bell-shaped structure that protrudes outward towards the center in the stacking direction (bell deformation).

[0125] In contrast, the formation of the step absorption pattern layer 60 reduces variations in the thickness of the inner dielectric layer 2, suppresses bell-shaped deformation of the element body 10, and suppresses deformation of the multilayer ceramic capacitor 1. By preventing deformation of the multilayer ceramic capacitor 1, the desired capacitance can be obtained, dielectric breakdown becomes less likely, and reliability can be improved.

[0126] Incidentally, as the multilayer ceramic capacitor 1 is made thinner, the strength of the inner green sheet 30 is improved, but this tends to reduce the adhesion between the step absorption pattern layer 60 and the inner green sheet 30.

[0127] One way to improve this tendency is to give the step-absorbing pattern layer 60 high adhesive strength. However, if the step-absorbing pattern layer 60 is given high adhesive strength, it tends to reduce handling performance during work, such as causing unexpected adhesion.

[0128] In contrast, the step-absorbing paste according to this embodiment contains a first ceramic powder, ethyl cellulose, and a predetermined terpene phenol in a predetermined composition. The step-absorbing paste according to this embodiment can improve the adhesion between the step-absorbing pattern layer 60 and the inner green sheet 30, as well as improve handling during operation.

[0129] The reason is as follows. In this embodiment, the inner green sheet 30 contains butyral resin, and the step absorption pattern layer 60 contains ethylcellulose. Furthermore, the step absorption pattern layer 60 contains terpene phenol at a predetermined concentration. Since terpene phenol is compatible with both butyral resin and ethylcellulose, when the green laminate 110 is pressed and heated to bond it, thermal diffusion increases the entanglement of molecular chains between the butyral resin and terpene phenol, as well as between the ethylcellulose and terpene phenol. In other words, at high temperatures during the lamination process, the adhesion between the inner green sheet 30 containing butyral resin and the step absorption pattern layer 60 containing ethylcellulose is improved via terpene phenol.

[0130] Furthermore, the adhesion between the step-absorbing pattern layer 60 and the inner green sheet 30 contributes to the lamination of the inner green sheet 30, effectively suppressing cracks in the element body 10 after firing.

[0131] Furthermore, the step-absorbing pattern layer 60 formed by the step-absorbing paste according to this embodiment has the characteristic of having low adhesive strength at low temperatures. Therefore, it has good handling properties during operations other than the lamination process. Specifically, it is possible to prevent the inner green sheet 30, etc. from unintentionally adhering to some substance during processes other than the lamination process, and it is also possible to prevent a part of the green laminate 110 from unintentionally adhering to the mold of the lamination machine, etc., when the green laminate 110 is pressed and heated to bond it.

[0132] In other words, the step-absorbing pattern layer 60 formed by the step-absorbing paste according to this embodiment has high adhesive strength at high temperatures during the lamination process, thus improving adhesion between the step-absorbing pattern layer 60 and the inner green sheet 30. On the other hand, it has low adhesive strength at low temperatures, such as the working temperature outside of the lamination process, thus improving handling.

[0133] Furthermore, in conventional technology, during the process of winding up a carrier sheet 20 on which an inner green sheet 30, an internal electrode pattern layer 40, and a step absorption pattern layer 60 are formed, the step absorption pattern layer 60, etc., may be transferred to the back surface of the carrier sheet 20 (back surface transfer). In contrast, the step absorption paste according to this embodiment has low adhesive strength at low temperatures, such as the working temperature other than the lamination process, thus preventing the above-mentioned back surface transfer.

[0134] Furthermore, in this embodiment, since the adhesive strength between the step-absorbing pattern layer 60 and the inner green sheet 30 is sufficiently high during the lamination process, the step-absorbing paste does not substantially need to contain a plasticizer. Therefore, in this embodiment, the absence of a plasticizer in the step-absorbing paste also contributes to high handling performance.

[0135] Although embodiments of the present invention have been described above, the present invention is not limited in any way to the embodiments described above, and can be modified in various ways without departing from the spirit of the invention.

[0136] For example, in the embodiments described above, a multilayer ceramic capacitor was used as an example of a multilayer electronic component according to the present invention. However, the multilayer electronic component according to the present invention is not limited to a multilayer ceramic capacitor, and can of course be applied to multilayer ceramic substrates and the like as well.

[0137] Alternatively, a predetermined number of laminated units may be formed by stacking an inner green sheet 30 formed by the method according to the present invention, an internal electrode pattern layer 40, and a step absorption pattern layer 60, and these laminated units may be further stacked to produce the final green laminate 110.

[0138] Furthermore, the internal electrode pattern layer 40 and the step absorption pattern layer 60 may be formed by a transfer method. [Examples]

[0139] The present invention will be described below based on more detailed examples, but the present invention is not limited to these examples.

[0140] 35°C adhesion and 75°C adhesion The adhesive strength at 35°C and 75°C was measured for the inner green sheet 30 on which the step absorption pattern layer 60 was formed, using the method described below. In Tables 1 to 3, "35°C adhesive strength" means "adhesive strength at 35°C," and "75°C adhesive strength" means "adhesive strength at 75°C."

[0141] The inner green sheet 30 (sample) on which the step absorption pattern layer 60 was formed was manufactured by the following method.

[0142] An inner dielectric paste was prepared for forming the inner green sheet 30. BaTiO3-based ceramic powder (second ceramic powder), polyvinyl butyral resin (degree of polymerization: 1700), propyl alcohol, xylene, methyl ethyl ketone, and 2-butoxyethyl alcohol as second organic solvents, and di-2-ethylhexyl phthalate as a plasticizer were prepared. Next, 100 parts by mass of the second ceramic powder were weighed out, along with the polyvinyl butyral resin, 150 parts by mass of the second organic solvent, and the plasticizer. These were then kneaded together with 2 mm diameter zirconia balls in a ball mill for 21 hours to form a slurry and obtain the inner dielectric paste.

[0143] Furthermore, when the content of the second ceramic powder in the inner dielectric paste was 100 parts by mass, the content of polyvinyl butyral resin (A2) in the inner dielectric paste was 12 parts by mass.

[0144] Furthermore, 10 parts by mass of plasticizer were added per 100 parts by mass of polyvinyl butyral resin.

[0145] Furthermore, the paste for the inner dielectric did not contain terpene phenols.

[0146] Next, a step-absorbing paste was prepared to form the step-absorbing pattern layer 60. First, a BaTiO3-based ceramic powder (first ceramic powder) with the same composition as the second ceramic powder contained in the inner dielectric paste described above, ethyl cellulose, terpene phenol having the average mass molecular weight listed in Tables 1 to 3, and α-terpinyl acetate as the first organic solvent were prepared. Then, 122 parts by mass of α-terpinyl acetate, ethyl cellulose (average mass molecular weight: 140,000), and terpene phenol were added to 100 parts by mass of the first ceramic powder, and this mixture was kneaded in a bead mill and a three-roll mill to form a slurry and obtain a step-absorbing paste.

[0147] Furthermore, when the total content of ethylcellulose and terpene phenol in the step-absorbing paste was set to 100 parts by mass, the content of plasticizer was 0.1 parts by mass or less.

[0148] Furthermore, the blending ratio of ethylcellulose and terpene phenol is as shown in Tables 1 to 3, under "A1 [parts by mass]" and "Terpene phenol content [parts by mass]".

[0149] In Tables 1 to 3, "A1 [parts by mass]" refers to the total content of ethylcellulose and terpene phenol when the content of the first ceramic powder is set to 100 parts by mass.

[0150] Furthermore, the "terpene phenol content [parts by mass]" listed in Tables 1 to 3 means "the terpene phenol content when the total content of ethyl cellulose and terpene phenols is set to 100 parts by mass."

[0151] Next, an inner dielectric paste was applied to the surface of the PET film, which served as the carrier sheet 20, to a predetermined thickness using a wire bar coater, and then dried to produce an inner green sheet 30 with a thickness of 0.6 μm.

[0152] Also, on the surface of the carrier sheet 20 (PET film), a paste for step absorption was applied with a wire bar coater to a predetermined thickness and dried to obtain a dried film of the step absorption paste with a thickness of 1.0 to 1.5 μm.

[0153] Note that neither the PET film on which the inner dielectric paste was formed nor the PET film on which the step absorption paste was formed was subjected to a peeling treatment. This is because this experiment is to confirm the adhesion between the step absorption pattern layer 60 and the inner green sheet 30. Therefore, it is desirable that the inner green sheet 30 does not peel from the PET film, and it is also desirable that the step absorption pattern layer 60 does not peel from the PET film.

[0154] The dried film of the step absorption paste formed on the PET film was cut out to an appropriate size, laminated with the inner green sheet 30, and a sample (inner green sheet 30 having a step absorption pattern layer 60) was obtained. The lamination was performed at a pressure of 2 MPa, a temperature of 35 °C or 75 °C, and a pressurization time of 10 minutes.

[0155] Using an Instron 5543 tensile testing machine, the sample was pulled in a direction perpendicular to the surface of the sample (pulled in the lamination direction of the sample), and the strength value at the time of peeling was converted to the adhesion strength of the sample per 1 cm square. The adhesion strength at 35 °C was less than 1 N / cm 2 and the adhesion strength at 75 °C was less than 1 N / cm 2 were considered good. Also, the adhesion strength at 75 °C of 5 N / cm 2 or more was considered better, and the adhesion strength at 75 °C of 40 N / cm 2 or more was considered even better. The results are shown in Tables 1 to 3.

[0156] The fact that the adhesion strength at 35 °C is less than 1 N / cm 2 means that it is possible to suppress unnecessary adhesion of the inner green sheet 30 or the like to some substance before pressurizing and heating the green laminate 110, which means that the handling property during work is good.

[0157] Furthermore, the adhesive strength at 75°C is 1 N / cm². 2 The above means that, in the lamination process which involves pressurization and heating, the adhesion between the step-absorbing pattern layer 60 and the inner green sheet 30 is good.

[0158] [Table 1]

[0159] [Table 2]

[0160] [Table 3]

[0161] From Tables 1 to 3, when A1 is 10 to 26 parts by mass, the average mass molecular weight of terpene phenol is 220 to 650, and the total content of ethyl cellulose and terpene phenol is 100 parts by mass, the terpene phenol content is 30 to 67 parts by mass (sample numbers 12 to 18, 21 to 25, 27 to 31, 33 to 41, 43 to 47, 49 to 56, 65 to 71), the 35°C adhesive strength is 1 N / cm. 2 Less than 1, and with a 75°C adhesive strength of 1 N / cm². 2 The above was confirmed. Specifically, samples 12-18, 21-25, 27-31, 33-41, 43-47, 49-56, and 65-71 showed good handling characteristics before heating, and good adhesion between the step absorption pattern layer 60 and the inner green sheet 30 during the lamination process after heating.

[0162] The multilayer ceramic capacitor 1 was manufactured using the following method.

[0163] The paste for the internal electrode to form the internal electrode pattern layer 40 was prepared by the following method. First, Ni particles with an average particle size of 0.2 μm were prepared as conductive powder, BaTiO3-based ceramic powder as a co-material, ethyl cellulose as a third organic binder, α-terpinyl acetate as a third organic solvent, and gum rosin as a tackifier. Then, 122 parts by mass of α-terpinyl acetate, 5.58 parts by mass of ethyl cellulose, and 2.22 parts by mass of gum rosin were added to 130 parts by mass of 100 parts by mass of conductive powder and 30 parts by mass of co-material, and this mixture was kneaded in a ball mill and a three-roll mill to form a slurry and obtain the paste for the internal electrode.

[0164] Next, a multilayer ceramic chip capacitor 1 was manufactured using the inner dielectric paste, internal electrode paste, and step absorption paste prepared as described above.

[0165] First, an inner dielectric paste was applied to the release-treated surface of the carrier sheet 20 (PET film) to a predetermined thickness using a wire bar coater, and then dried to produce an inner green sheet 30 with a thickness of 0.6 μm.

[0166] Next, an internal electrode pattern layer 40 (see Figure 2B) was formed on the obtained inner green sheet 30 by screen printing using an internal electrode paste, such that the screen pattern was in the shape of strips measuring 4.0 × 1.2 mm and had a thickness of 0.6 μm after drying.

[0167] Subsequently, a step-absorbing pattern layer 60 (see Figure 2C) with substantially the same thickness as the internal electrode pattern layer 40 was formed on the blank pattern portion 50 (see Figure 2B) on the inner green sheet 30 where the internal electrode pattern layer 40 was not formed, by a screen printing method using a step-absorbing paste, thereby obtaining an inner green sheet 30 having the internal electrode pattern layer 40 and the step-absorbing pattern layer 60 as shown in Figure 2C. In this embodiment, multiple inner green sheets 30 having the internal electrode pattern layer 40 and the step-absorbing pattern layer 60 were prepared.

[0168] Next, an outer dielectric paste was prepared in the same manner as the inner dielectric paste prepared above, except that the degree of polymerization of the polyvinyl butyral resin was set to 1500. This outer dielectric paste was applied to the release-treated surface of the PET film 20 to a predetermined thickness using a wire bar coater and dried to produce an outer green sheet with a thickness of 12 μm.

[0169] Eight of these outer green sheets were prepared and heat-pressed together to form an outer green laminate 110b with a thickness of 96 μm.

[0170] On the obtained outer green laminate 110b, a green sheet 30 with an internal electrode pattern layer 40 and a step absorption pattern layer 60 formed on it was pressed onto the laminate at a temperature of 75°C and a pressure of 12 MPa, and the PET film 20 was peeled off (see Figure 3A). This process was repeated to laminate a desired number of inner green sheets 30 with internal electrode pattern layers 40 and step absorption pattern layers 60 formed on them (see Figure 3B). Subsequently, the outer green laminate 110b with a thickness of 96 μm was further formed by thermocompression bonding to obtain the green laminate 110.

[0171] Next, the obtained green laminate 110 was cut to a predetermined size, and then subjected to binder removal, firing, and annealing under the following conditions to obtain the element body 10.

[0172] Binder removal was performed under the following conditions: heating rate: 15°C / hour, holding temperature: 280°C, holding time: 8 hours, and processing atmosphere: air atmosphere.

[0173] The firing process involved a heating rate of 200°C / hour, holding temperature of 1200-1380°C, holding time of 2 hours, cooling rate of 300°C / hour, and a reducing atmosphere (oxygen partial pressure: 10%). -6 The experiment was conducted under the following conditions: (Pa was adjusted by passing a mixed gas of N2 and H2 through water vapor).

[0174] Annealing was performed under the following conditions: holding temperature: 900°C, holding time: 9 hours, cooling rate: 300°C / hour, and processing atmosphere: humidified N2 gas atmosphere. A wetter was used to humidify the gas during firing and annealing, with a water temperature of 35°C.

[0175] The obtained device body 10 had dimensions of L0:1.6mm × W0:0.8mm × H0:0.8mm, with the inner dielectric layer 2 sandwiched between the pair of internal electrode layers 3 having a thickness of approximately 0.6μm, and the internal electrode layer 3 having a thickness of 0.6μm. [Explanation of Symbols]

[0176] 1… Multilayer ceramic capacitor 10… Element body 10a… Interior finishing area 10b…Exterior area 10c… Margin area 2… Inner dielectric layer (inner ceramic layer) 3a,3b… Internal electrode layer 4a,4b… External electrode 20… Carrier seat 30… Inner green sheet 40… Internal electrode pattern layer 50... Margin pattern section 60… Step absorption pattern layer 110… Green laminate 110a... Green laminate for interior areas 110b… Green laminate for exterior area 110c… Margin area green laminate

Claims

1. A step-absorbing paste comprising a first ceramic powder, ethyl cellulose, and terpene phenol, A1 is 10 to 26 parts by mass, A1 is the total content of ethylcellulose and terpene phenol in the step-absorbing paste when the content of the first ceramic powder in the step-absorbing paste is 100 parts by mass. The average mass molecular weight of the terpene phenol is 220 to 650. A step-absorbing paste wherein, when the total content of the ethylcellulose and the terpene phenol is 100 parts by mass, the content of the terpene phenol is 30 parts by mass to 67 parts by mass.

2. A method for manufacturing a stacked electronic component, comprising the step of alternately stacking an inner ceramic green sheet and an internal electrode pattern layer to obtain a green stacked body, A step-absorbing pattern layer is formed in the gap of the internal electrode pattern layer. The aforementioned inner ceramic green sheet is formed using an inner ceramic paste, The aforementioned paste for the inner ceramic contains a second ceramic powder and a butyral resin. The step-absorbing pattern layer is formed using a step-absorbing paste. The aforementioned step-absorbing paste comprises a first ceramic powder, ethyl cellulose, and terpene phenol. A1 is 10 to 26 parts by mass, A1 is the total content of ethylcellulose and terpene phenol in the step-absorbing paste when the content of the first ceramic powder in the step-absorbing paste is 100 parts by mass. The average mass molecular weight of the terpene phenol is 220 to 650. A method for manufacturing a multilayer electronic component, wherein when the total content of the ethylcellulose and the terpene phenol is 100 parts by mass, the content of the terpene phenol is 30 parts by mass to 67 parts by mass.

3. A method for manufacturing a stacked electronic component according to claim 2, wherein the components of the first ceramic powder and the second ceramic powder are substantially the same.

4. A2 is greater than 10 parts by mass and less than or equal to 20 parts by mass. A2 is the content of the butyral resin in the inner ceramic paste when the content of the second ceramic powder in the inner ceramic paste is 100 parts by mass. The method for manufacturing a stacked electronic component according to claim 2 or 3, wherein A1 is greater than or equal to A2.

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