Manufacturing method for multilayer ceramic electronic components

Abstract

The present invention provides a novel method for producing a multilayer ceramic electronic component. [Solution] The method for manufacturing a multilayer ceramic electronic component of the present invention includes a sheet formation process in which a dielectric paste is applied to a polylactic acid-based carrier film to form a green sheet layer, and a firing process in which the green sheet layer on the polylactic acid-based carrier film is fired.

Description

[Technical Field]

[0001] The present invention relates to a method for manufacturing a multilayer ceramic electronic component. [Background technology]

[0002] Known multilayer ceramic electronic components include capacitors, inductors, piezoelectric elements, thermistors, and all-solid-state batteries.

[0003] For example, a method for manufacturing a multilayer ceramic capacitor includes a sheet forming step of applying a dielectric paste onto a carrier film to form green sheet layers, an electrode forming step of printing internal electrodes on the green sheet layers, a sheet laminating step of peeling the carrier film from the green sheet layers with the printed internal electrodes and laminating the green sheets, a pressure bonding step of pressing the laminated green sheet layers via a press film, a cutting step of cutting the pressed laminated green sheet layers into chips, and a firing step of firing the chipped laminated green sheet layers. Other multilayer ceramic electronic components also include similar steps. PET film is typically used as the carrier film.

[0004] Dielectric pastes typically use ethyl cellulose, polyvinyl butyral, or the like as binders, but as disclosed in Patent Documents 1 and 2, it is also known that acrylic resins, polylactic acid, and the like are used as binders.

[0005] Patent Document 3 discloses a green sheet for ceramic lamination, which is formed by forming a thermoplastic resin layer on at least one side of a ceramic green sheet, and describes a green sheet for ceramic lamination in which a carrier sheet made of PET / PLA is produced, the PET layer of the carrier sheet is peeled off, and a PLA layer is formed on one side of the ceramic green sheet. [Prior art documents] [Patent documents]

[0006] [Patent Document 1] International Publication No. 2014 / 084273 [Patent Document 2] Japanese Patent Application Publication No. 2023-130209 [Patent Document 3] Japanese Patent Application Laid-Open No. 2002-338364 Summary of the Invention [Problem to be solved by the invention]

[0007] An object of the present invention is to provide a novel method for producing a multilayer ceramic electronic component. [Means for solving the problem]

[0008] The present invention has the following aspects. <<Aspect 1>> A method for manufacturing a multilayer ceramic electronic component, comprising: a sheet forming step of applying a dielectric paste onto a polylactic acid-based carrier film to form a green sheet layer; and a firing step of firing the green sheet layer on the polylactic acid-based carrier film. <<Aspect 2>> an electrode forming step of printing internal electrodes on the green sheet layer on the polylactic acid-based carrier film; and a sheet laminating step of laminating the green sheet layer on which the internal electrodes are printed, The manufacturing method according to aspect 1, wherein the outermost polylactic acid-based carrier film is not peeled off from the green sheet layer during the period from the sheet forming step to the completion of the firing step. Aspect 3 The manufacturing method according to aspect 2, further comprising a pressure bonding step of pressing the polylactic acid-based carrier film as a press film. Aspect 4 2. The manufacturing method according to aspect 1, wherein the dielectric paste contains at least one resin selected from an acrylic resin and a polylactic acid as a binder. Aspect 5 The method according to any one of aspects 1 to 4, wherein the multilayer ceramic electronic component is a multilayer ceramic capacitor. Aspect 6 The method according to any one of Aspects 1 to 4, wherein the multilayer ceramic electronic component is an all-solid-state battery. DETAILED DESCRIPTION OF THE INVENTION

[0009] The present invention will be specifically described using the following embodiments as examples, but the present invention is not limited thereto. Unless specific details are mentioned for each process, device, mechanism, means, etc. in this specification, those skilled in the art can use methods, mechanical devices, mechanisms, means, etc. that are well known. Each embodiment can be combined based on the common knowledge of those skilled in the art, and configurations not specifically mentioned in each embodiment can have the same configuration as other embodiments or a configuration appropriate for that embodiment.

[0010] <<Method for manufacturing multilayer ceramic electronic components>> The method for manufacturing a multilayer ceramic electronic component of the present invention includes a sheet formation step of applying a dielectric paste onto a polylactic acid-based carrier film to form a green sheet layer, and a firing step of firing the green sheet layer on the polylactic acid-based carrier film.

[0011] The present inventors have focused on the fact that polylactic acid is substantially completely eliminated by firing under the firing conditions of ordinary multilayer ceramic electronic components, and have discovered a new method for manufacturing multilayer ceramic electronic components in which a dielectric paste is applied to a polylactic acid-based carrier film, a green sheet layer is formed, and the green sheet layer is fired without peeling off the polylactic acid-based carrier film. This method is advantageous because it not only reduces the number of steps compared to conventional methods for manufacturing multilayer ceramic electronic components, but also suppresses problems such as misalignment and cracks between layers that can occur when peeling off the carrier film from the multilayer green sheet layer.

[0012] Furthermore, this method makes it possible to use acrylic resin and polylactic acid, which have not been actively used as binders for dielectric pastes in the past because they can exacerbate problems such as misalignment between green sheet layers when the carrier film is peeled off. These binders leave less carbon residue after firing and have excellent firing properties compared to commonly used binders such as ethyl cellulose and polyvinyl butyral, so the manufacturing method of the present invention is also advantageous in that it can use these binders.

[0013] <Sheet forming process> In the sheet forming step, a dielectric paste is applied onto a carrier film to form a green sheet layer.

[0014] In the manufacturing method of the present invention, a polylactic acid-based carrier film is used as the carrier film. The polylactic acid-based carrier film can be a single-layer film essentially consisting of polylactic acid, but it may also contain resins other than polylactic acid and other additives as long as they can be substantially completely eliminated in the baking process. A single-layer film is preferred because it is less likely to produce carbon residue than a laminated film.

[0015] The polylactic acid-based carrier film may contain 50% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, or 98% by weight or more of polylactic acid, or 100% by weight or less, 95% by weight or less, or 90% by weight or less.

[0016] The thickness of the polylactic acid-based carrier film may be, for example, 5 μm or more, 10 μm or more, 20 μm or more, 40 μm or more, 50 μm or more, 80 μm or more, 100 μm or more, or 200 μm or more, or 500 μm or less, 300 μm or less, 200 μm or less, 150 μm or less, 100 μm or less, 80 μm or less, or 50 μm or less.

[0017] The surface of the polylactic acid-based carrier film may have a release layer made of silicone resin or the like, but according to the manufacturing method of the present invention, it is not necessary to include a carrier film peeling step, and even taking into account the effect of carbon residue generation, the polylactic acid-based carrier film used does not need to have a release layer.

[0018] The dielectric paste is not particularly limited, but for example, a ceramic dielectric slurry containing a mixture of ceramic dielectric powder, additive powder, binder, solvent, etc. can be used. The ceramic dielectric slurry can be either solvent-based or water-based. In the case of a solvent-based slurry, examples of organic solvents include methyl cellosolve, ethyl cellosolve, butyl cellosolve, butyl carbitol acetate, methyl ethyl ketone, dioxane, acetone, cyclohexanone, cyclopentanone, ethanol, isobutyl alcohol, isopropyl alcohol, 3-methoxy-3-methyl-1-butanol, tetrahydrofuran, dimethyl sulfoxide, γ-butyrolactone, terpineol, bromobenzene, chlorobenzene, dibromobenzene, dichlorobenzene, ethyl acetate, and toluene. A mixture of organic solvents can also be used.

[0019] The ceramic dielectric powder may be, for example, BaTiO powder, and the ceramic powder mixture containing additives may be wet-pulverized and mixed in a bead mill. The additives may be, for example, oxides or glasses of Mg, Mn, V, Cr, Y, Sm, Eu, Gd, Tb, Dy, Ho, Er, Tm, Yb, Co, Ni, Li, B, Na, K, or Si.

[0020] As the binder, conventionally used ethyl cellulose, polyvinyl butyral, etc. may be used, but in particular, acrylic resin and / or polylactic acid can be used. Examples of acrylic resin-based binders include acrylic resins such as those described in Patent Document 1, and examples of polylactic acid-based binders include polylactic acids such as those described in Patent Document 2. Binders using acrylic resin and / or polylactic acid are preferred because they leave relatively little carbon residue after firing compared to ethyl cellulose and polyvinyl butyral-based binders.

[0021] Specifically, the acrylic resin binder may be a (meth)acrylic polymer containing 20 to 100 mol % of a structural unit derived from a specific monomer (a).

[0022] Here, specific monomers (a) include isobutyl (meth)acrylate, 2-ethylhexyl methacrylate, 2-hydroxyisobutyl (meth)acrylate, 2-hydroxyisopropyl (meth)acrylate, 2,2,4-trimethyl-3-hydroxypentyl (meth)acrylate, cyclohexanedimethanol mono(meth)acrylate, 2-(meth)acryloyloxyethyl hexahydrophthalic acid, pentamethylpiperidyl (meth)acrylate, tetramethylpiperidyl (meth)acrylate, 2,2-dimethyl- Preferably, the monomer (a) is selected from the group consisting of 3-hydroxypropyl (meth)acrylate, hydroxycyclohexyl (meth)acrylate, 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine, and a reaction product of dicyclopentenyl (meth)acrylate with maleic anhydride, and more preferably from the group consisting of isobutyl (meth)acrylate, 2-ethylhexyl methacrylate, 2-hydroxyisobutyl (meth)acrylate, and 4-(meth)acryloyloxy-2,2,6,6-tetramethylpiperidine. It is even more preferred that the monomer (a) contains 70 to 100 mol % of structural units derived from the monomer (a).

[0023] The weight average molecular weight of the (meth)acrylic polymer is preferably 1,000 to 200,000, and more preferably 5,000 to 100,000.

[0024] The polylactic acid binder may be polylactic acid consisting of only L-components or D-components, or may be polylactic acid containing both L-components and D-components.

[0025] The weight average molecular weight of the polylactic acid is preferably 20,000 to 300,000, and more preferably 30,000 to 200,000.

[0026] The binder in the dielectric paste may contain acrylic resin or polylactic acid at 50% by weight or more, 70% by weight or more, 80% by weight or more, 90% by weight or more, 95% by weight or more, or 98% by weight or more, or may contain 100% by weight or less, 95% by weight or less, or 90% by weight or less.

[0027] The dielectric paste can be applied to the carrier film by a known method such as a doctor blade method, a die coater method, or a gravure coater method. The applied dielectric paste is dried to form a green sheet. From the viewpoint of miniaturization and high capacity of the multilayer ceramic capacitor, the thickness of the green sheet is preferably, for example, 10 μm or less, 5 μm or less, or 3 μm or less.

[0028] <Electrode formation process> In the electrode formation step, internal electrodes are printed on the green sheet layers obtained as described above. In this step, a predetermined internal electrode pattern is formed on the green sheet layers, for example, by applying a conductive paste to the green sheet layers in a predetermined pattern.

[0029] The conductive paste may be, for example, a mixture of a metal powder such as Ni, Pd, Cu, Ag, or an alloy powder thereof and a binder in a solvent, and may further contain a ceramic fine powder. The binder may be the same as that used in the dielectric paste, and in particular, an acrylic resin and / or polylactic acid. The solvent for the conductive paste may be the same as the organic solvents listed for the dielectric paste.

[0030] The conductive paste can be applied by screen printing, inkjet printing, gravure printing, or the like. The applied conductive paste is dried to form internal electrodes on the green sheet layers. From the viewpoint of miniaturization and high capacity of the multilayer ceramic capacitor, the thickness of the internal electrodes is preferably 5 μm or less, 3 μm or less, or 1.5 μm or less.

[0031] <Sheet lamination process> In the sheet laminating step, green sheet layers on which internal electrodes are printed are laminated together.

[0032] In the sheet lamination process, the carrier film is peeled off and the green sheet layers are laminated, but when a polylactic acid-based carrier film is used, the green sheet layers can also be laminated together with the carrier film. Even when the carrier film is peeled off and the green sheet layers are laminated, the outermost layer of the carrier film is not peeled off and can be removed during the firing process. Even when the green sheet layers are laminated together with the carrier film, the outermost layer and the intermediate layer of the carrier film sandwiched between them can be removed during the firing process.

[0033] Preferably, in the sheet lamination step, the polylactic acid-based carrier film is not peeled off from the green sheet layer that is the outermost layer, but the carrier film is peeled off from the green sheet layers that are to be laminated as the second, third, etc. layers, and these can be laminated onto the green sheet layer on the polylactic acid-based carrier film. When peeling the carrier film from the green sheet layer that is the outermost layer, problems such as misalignment of the laminated green sheet layer can occur, but by not peeling the carrier film from the outermost layer of the laminated green sheet layer, these problems tend to be alleviated.

[0034] The green sheet layer to be laminated as an intermediate layer on the green sheet layer on the polylactic acid-based carrier film to be the outermost layer can be laminated by peeling off the carrier film using a peeling device such as that described in JP-A-2004-31489. The carrier film used for the green sheet layer to be the intermediate layer can be a polylactic acid-based carrier film, but when peeling off the carrier film and laminating, there is no particular limitation, and a conventionally used PET film or the like can also be used.

[0035] <Crimping process> In the pressure bonding step, the stacked green sheet layers are pressed together with a press film between them. As the press film, a conventionally used PET film or the like can be used, but a polylactic acid film can also be used.

[0036] When a polylactic acid-based film is used as the press film, it can be eliminated during the baking process, eliminating the need for a process to recover the press film after the pressure-bonding process, which is extremely advantageous in terms of reducing the number of processes. Note that when a polylactic acid-based film is used as the press film, it can be the same or equivalent to the polylactic acid-based film used as the carrier film.

[0037] <Cutting process> In the cutting step, the laminated green sheet layer pressed in the pressure bonding step is cut into chips. In this step, the laminated green sheet layer is cut to a predetermined size using a dicing saw, a press cutter, or the like, to obtain chipped laminated green sheet layers. The chipped laminated green sheet layer can include a polylactic acid-based carrier film as the outermost layer.

[0038] <Firing process> In the cutting step, the chipped laminated green sheet layer is fired. The laminated green sheet layer up to this step may contain a polylactic acid-based carrier film, which can be removed by the firing step.

[0039] Specifically, the firing step can include degreasing and firing. The degreasing is performed by heating the laminated green sheet layer in a nitrogen atmosphere furnace to, for example, about 400°C to 700°C, and the subsequent firing is performed in a hydrogen-containing atmosphere reduction furnace with the peak temperature controlled to, for example, 800°C to 1300°C, and the chipped laminated green sheet layer is sintered to obtain a multilayer ceramic electronic component.

[0040] <others> This method may further include a step of forming external electrodes on the multilayer ceramic electronic component, etc. For example, a base electrode layer is formed by firing a conductive paste applied to the end portions of the multilayer ceramic electronic component, and the base electrode layer is then plated with Ni and Sn in this order to form plating layers, thereby forming external electrodes on the multilayer ceramic electronic component.

[0041] Furthermore, depending on various uses of the multilayer ceramic electronic component, the manufacturing method of the present invention may include known steps as appropriate.

[0042] The multilayer ceramic electronic component obtained by the manufacturing method of the present invention is not particularly limited as long as it includes the manufacturing steps described above. Examples of multilayer ceramic electronic components include capacitors, inductors, piezoelectric elements, thermistors, and all-solid-state batteries. In particular, all-solid-state batteries are known to be manufactured by stacking layers of solid electrolytes such as sulfides and electrodes, and include the manufacturing steps described above.

[0043] The present invention will be explained in more detail in the following examples, but the present invention is not limited thereto. [Example]

[0044] 《Manufacturing》 A dielectric paste was prepared from a composition consisting of 100 parts ceramic powder (barium titanate), 5 parts acrylic resin, 1 part plasticizer (dioctyl phthalate), and 50 parts toluene. The acrylic resin was a resin with a weight-average molecular weight of 50,000 prepared from monomer components consisting of 2-ethylhexyl methacrylate / isobutyl methacrylate / 2-hydroxyethyl methacrylate in a ratio of 78 / 20 / 2 (parts by mass).

[0045] As a paste for the internal electrodes, a composition consisting of 45 parts of Ni powder, 5 parts of polylactic acid having a weight average molecular weight of 20,000, and 50 parts of butyl carbitol acetate was prepared.

[0046] Example 1 The dielectric paste was applied to a 25 μm thick polylactic acid-based carrier film by a doctor blade method and dried for 5 minutes at 110° C. to form a 10 μm thick green sheet layer on the carrier film. Next, an internal electrode pattern was screen-printed on the green sheet layer using an internal electrode paste to obtain sheet (I).

[0047] Thereafter, a plurality of sheets (I) were laminated to obtain a laminated sheet (II). The carrier film was peeled off each time the sheets (I) were laminated. The obtained laminated sheet (II) was then pressed under pressure to obtain a laminate. During the pressing, a polylactic acid film was placed between the press mold and the sheet (II).

[0048] "evaluation" The laminate of Example 1 was cut to a predetermined size and then subjected to a firing treatment under the following conditions. Heating rate: 10℃ / min Start temperature: 30℃ ·Holding temperature: 500℃, Holding time: 1 hour Heating rate: 10℃ / min ·Holding temperature: 900℃, Holding time: 2 hours ·Cooling rate: 5℃ / min Atmospheric gas: 97% N2 + 3% H2 gas

[0049] After firing, the carrier film disappeared from the laminate of Example 1, and a multilayer ceramic was obtained.

[0050] <Reference example> The PLA film and 25 μm PET film (Lumirror #25-T60, manufactured by Toray Industries, Inc.) used in Example 1 were visually inspected for sinterability using TG-DTA under the following conditions. No residual carbon was observed in the PLA film, but clear residual carbon was confirmed in the PET film. Device name: Hitachi High-Tech Science STA7220 Atmosphere: N2 200mL / min Temperature conditions: 30°C → 500°C (heating rate: 10°C / min) Sample container: Aluminum open cell

Claims

1. A method for manufacturing a multilayer ceramic electronic component, comprising: a sheet forming step of applying a dielectric paste onto a polylactic acid-based carrier film to form a green sheet layer; and a firing step of firing the green sheet layer on the polylactic acid-based carrier film.

2. an electrode forming step of printing internal electrodes on the green sheet layer on the polylactic acid-based carrier film; and a sheet laminating step of laminating the green sheet layer on which the internal electrodes are printed, The manufacturing method according to claim 1 , wherein the outermost polylactic acid-based carrier film is not peeled off from the green sheet layer during the period from the sheet forming step to the completion of the firing step.

3. The manufacturing method according to claim 2 , further comprising a pressure bonding step of pressing the polylactic acid-based carrier film as a press film.

4. The manufacturing method according to claim 1 , wherein the dielectric paste contains at least one resin selected from an acrylic resin and a polylactic acid as a binder.

5. The method according to any one of claims 1 to 4, wherein the multilayer ceramic electronic component is a multilayer ceramic capacitor.

6. The manufacturing method according to any one of claims 1 to 4, wherein the multilayer ceramic electronic component is an all-solid-state battery.