JP2004291455A - Ceramic green sheet and its manufacturing method, and multilayer electronic component and its manufacturing method - Google Patents

Abstract

An object of the present invention is to provide a ceramic green sheet that eliminates disadvantages of an aqueous green sheet and an organic solvent green sheet and that can achieve total cost reduction.
The first and second green sheets (4, 6) are water-based green sheets due to crosslinking by irradiation with an electron beam (3), but have a property of being hardly affected by environmental humidity. When the second green sheets 4 and 6 are stacked and pressure-bonded, it is possible to reliably prevent the occurrence of lamination displacement due to deformation or elongation such as thickness variation due to the influence of environmental humidity. Further, since the first and second green sheets 4 and 6 do not use an organic solvent as a slurry solvent as in the organic solvent-based green sheet, the working environment is contaminated by the organic solvent evaporated in the sheet manufacturing process or the like. The problem and the problem that the environment outside the factory is polluted by the organic solvent discharged from the factory can be avoided beforehand, the cost for taking measures against these problems is reduced, and the material cost related to the solvent is reduced. It is possible to reduce the cost for sheet production.
[Selection diagram] Fig. 1

Description

[0001]
TECHNICAL FIELD OF THE INVENTION
The present invention relates to a ceramic green sheet and a method for manufacturing the same, and a multilayer electronic component and a method for manufacturing the same.
[0002]
[Prior art]
A ceramic green sheet used for manufacturing a multilayer electronic component such as a multilayer ceramic capacitor is generally prepared by applying a slurry containing at least a ceramic powder, a binder and a solvent to an object to be coated such as a film and drying the slurry. .
[0003]
The green sheets are roughly classified into aqueous green sheets and organic solvent green sheets according to the type of solvent and binder used. Incidentally, the water-based green sheet uses water as a solvent, and refers to one using a water-soluble synthetic resin as a binder, while the organic solvent-based green sheet uses an organic solvent such as an alcohol as a solvent, and And a binder using a synthetic resin soluble in an organic solvent as a binder.
[0004]
Water-based green sheets have the advantage of lower material costs related to solvents compared to organic solvent-based green sheets, but because of their susceptibility to the effects of environmental humidity, especially when stacking and pressing green sheets, thickness fluctuations etc. Organic solvent-based green sheets that do not have the above-mentioned disadvantages are mainly used in recent years, because there is a disadvantage that lamination displacement due to deformation or elongation is likely to occur.
[0005]
[Problems to be solved by the invention]
By the way, recently, even with organic solvent-based green sheets, there is a problem that the working environment is polluted by the organic solvent evaporated during the sheet manufacturing process and the problem that the environment outside the factory is polluted by the organic solvent discharged from the factory. It is pointed out.
[0006]
For the former problem, measures such as forcing workers to wear protective equipment are taken.However, concerns about health deterioration due to long-term engagement cannot be eliminated, and in some cases, safety of workers is protected. There is also a need to install explosion-proof equipment. For the latter problem, measures such as providing a purifying device for rendering the organic solvent harmless have been taken.
[0007]
However, both of these problems require considerable costs to take countermeasures, and the cost of materials related to the solvent is increased. It has become difficult to reduce the unit price of die-type electronic components.
[0008]
The present invention has been made in view of the above circumstances, and aims to eliminate the disadvantages of aqueous green sheets and organic solvent green sheets, to achieve a total cost reduction, and a method for manufacturing the same. To provide a multilayer electronic component and a method of manufacturing the same.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a ceramic green sheet of the present invention is a green sheet manufactured by applying a slurry containing at least a ceramic powder, a binder and a solvent on an object to be coated. It is characterized in that a resin is used, water is used as a solvent, and a cross-linking treatment by electron beam irradiation is performed after the slurry is applied on the object to be coated.
[0010]
This ceramic green sheet is a water-based green sheet that has the property of being less affected by environmental humidity due to cross-linking treatment by electron beam irradiation. It is possible to prevent the occurrence of stacking deviation due to deformation or elongation such as fluctuation in the thickness. In addition, since this green sheet does not use an organic solvent as a slurry solvent like an organic solvent-based green sheet, there is a problem that the working environment is contaminated by an organic solvent evaporated in a sheet manufacturing process or the like, and the green sheet is discharged from a factory. In addition to avoiding the problem of the environment outside the factory being polluted by the organic solvent, the cost for taking measures against these problems can be reduced, and the material cost for the solvent can be reduced to reduce the sheet manufacturing cost.
[0011]
Further, the method for producing a ceramic green sheet of the present invention is a method for producing a green sheet by applying a slurry containing at least a ceramic powder, a binder and a solvent onto an object to be coated, wherein a water-soluble resin is used as a binder. The method is characterized in that a slurry using water as a solvent is used, and the slurry is applied on an object to be coated and then irradiated with an electron beam to perform a crosslinking treatment.
[0012]
According to the method for manufacturing a ceramic green sheet, the ceramic green sheet can be manufactured accurately and stably.
[0013]
On the other hand, the laminated electronic component of the present invention comprises a step of applying a slurry containing at least a ceramic powder, a binder and a solvent on an object to form a first green sheet, and a step of forming a conductor containing at least a metal powder, a binder and a solvent. Applying a paste on the first green sheet to form a second green sheet having an unsintered conductor layer, stacking a large number of the first green sheets and the second green sheets in a predetermined order, and pressing and bonding the unsintered laminate A multilayer electronic component manufactured by using at least the step of forming a first green sheet, wherein the slurry in the first green sheet forming step uses a water-soluble resin as a binder and water as a solvent, and is coated with the slurry. It is characterized in that a cross-linking treatment by electron beam irradiation is performed after coating on the coating body.
[0014]
According to this laminated electronic component, the first and second green sheets, which are water-based green sheets but have the property of being hardly affected by environmental humidity, use the same quality as the case of using organic solvent-based green sheets. The laminated electronic component provided can be accurately manufactured, the miniaturization of the laminated electronic component can be appropriately performed, and the unit cost of the laminated electronic component can be reduced by reducing the sheet manufacturing cost.
[0015]
In addition, the method for manufacturing a multilayer electronic component according to the present invention includes a step of applying a slurry containing at least a ceramic powder, a binder and a solvent on an object to form a first green sheet; A step of applying a conductor paste containing at least on the first green sheet to form a second green sheet having an unsintered conductor layer; and stacking and compressing a large number of the first green sheet and the second green sheet in a predetermined order. A method for producing a laminated electronic component using at least a step of producing an unfired laminate, wherein in a first green sheet producing step, a slurry using water-soluble resin as a binder and water as a solvent is used. The method is characterized in that, after the slurry is applied on the object to be coated, an electron beam is irradiated to perform a crosslinking treatment.
[0016]
According to the method for manufacturing a multilayer electronic component, the multilayer electronic component can be manufactured accurately and stably.
[0017]
The above and other objects, constitutional features, and operational effects of the present invention will become apparent from the following description and the accompanying drawings.
[0018]
BEST MODE FOR CARRYING OUT THE INVENTION
1 to 5 show an embodiment in which the present invention is applied to a multilayer ceramic capacitor.
[0019]
When manufacturing a multilayer ceramic capacitor, first, barium titanate (BaTiO ₃ ) or a material in which part of the Ba site of BaTiO ₃ is replaced with one or more of Ca, Sr, Mg, and Pb, or a Ti site of BaTiO ₃ a dielectric material having a perovskite structure comprising a part Zr, one or some of those substituted with both and Bao of Sn SrO, CaO, from such as those substituted with one or more of MgO of, _{Ho 2} A reduction-resistant ceramic powder containing at least a rare-earth oxide such as O ₃ or CeO ₂ or a reduction-resistant material made of MnO ₂ is prepared.
[0020]
Then, a slurry is prepared by mixing and kneading the ceramic powder, a binder made of a water-soluble resin, and a solvent made of water at an appropriate weight ratio. As the water-soluble resin, those having a polar group in the polymer and soluble in water, for example, a polyacetal resin such as polyvinyl butyral, a polyvinyl alcohol resin, a methacrylic resin (acrylic resin) such as polyacrylamide, etc. are appropriately used. Can be used. The state of the resin may be a state completely dissolved in water or an emulsion state. Incidentally, the weight ratio of the binder (water-soluble resin) in the slurry is generally 2 to 15% by weight, but is not limited to this numerical range because the optimum addition amount varies depending on the powder properties of the ceramic powder to be used. In addition, an appropriate amount of a dispersant such as a surfactant, a plasticizer, or various additives such as a crosslinking accelerator may be added to the slurry as needed.
[0021]
Next, as shown in FIG. 1 (A), the slurry is applied to a carrier film 1 made of polyethylene terephthalate (PET) or the like by a coating method using a doctor blade, a die coater or the like to a predetermined thickness. Create 2.
[0022]
Next, as shown in FIG. 1 (B), the slurry applied material 2 is irradiated with an electron beam 3 from an electron beam irradiation device (not shown) to cause a crosslinking reaction in a binder in the slurry applied material 2 to cause crosslinking. Thereafter, a drying process is performed to evaporate water in the slurry application material 2 to form the first green sheet 4.
[0023]
The electron beam used at this time is not particularly limited, but industrially, γ-rays from cobalt 60 or electron beams from an accelerator are desirable. In the case of an electron beam using an accelerator, there is no particular limitation on the acceleration voltage as long as the desired water resistance can be obtained.
[0024]
The dose of electron beam irradiation in the crosslinking treatment is 1 to 300 kGy, preferably 10 to 150 kGy. When the dose is small, the effect of crosslinking decreases.On the other hand, when the dose is large, the effect of crosslinking is sufficient but the cost increases. It is preferable to select and use. The irradiation atmosphere may be an oxidizing atmosphere such as the air, a reducing atmosphere such as N ₂ or N ₂ + H _2, or an atmosphere having a low oxygen partial pressure. Further, the above-described drying treatment may be performed before the crosslinking treatment, but the crosslinking treatment can be performed more uniformly when the drying treatment is performed before the drying treatment in which the binder particles have fluidity.
[0025]
Next, as shown in FIG. 2, a conductive paste obtained by mixing and kneading a base metal powder such as Ni and Cu, a binder, a solvent, and the like at an appropriate weight ratio is used to form a thick film by a screen printing method, a gravure printing method, or the like. The first green sheet 4 is printed on the first green sheet 4 by a predetermined thickness by a method, and thereafter, a drying process is performed to form the second green sheet 6 having the unfired internal electrode layer 5. In the conductor paste, an organic solvent such as an alcohol solvent is used as a solvent, and, in addition to a synthetic resin soluble in an organic solvent as a binder, water is used as a solvent, and a water-soluble binder is used. Those using a synthetic resin can be appropriately used.
[0026]
Next, as shown in FIG. 3, one or more first green sheets 4 (two sheets in the figure) are stacked, and a required number of second green sheets 6 (eight sheets in the figure) are stacked thereon. Then, one or more first green sheets 4 (three sheets in the figure) are laminated thereon, and finally pressure is applied to the whole to increase the degree of pressure bonding to form the unit laminate 7.
[0027]
The above-described lamination includes a method in which a green sheet is stacked on a lower green sheet, pressure-bonded, and then the carrier film 1 is peeled off, and the entire green sheet is pressed. It is possible to adopt a method in which several steps obtained by repeating the procedure of laminating the carrier film 1 a predetermined number of times after being stacked on the sheet and pressure-bonding them are prepared, stacked, and then pressurized as a whole.
[0028]
Next, as shown in FIG. 4, the unit laminate 7 is put into a firing furnace (not shown), and under a reducing atmosphere such as N ₂ or N ₂ + H ₂ or an atmosphere having a low oxygen partial pressure, 300 to 600. C. for about 20 to 40 hours to perform de-buying, followed by main baking for about 2 hours at a temperature of about 1300.degree. To form a unit chip 8 having a structure stacked through the steps.
[0029]
Next, as shown in FIG. 5, the same conductive paste as described above is applied to opposing ends of the unit chips 8 where the edges of the internal electrodes 9 are alternately exposed by a method such as a dipping method or a roll coating method. In a similar reducing atmosphere or an atmosphere having a low oxygen partial pressure, the external electrode 10 is formed by baking at a temperature of 700 to 900 ° C. for about 1 hour.
[0030]
The baking of the external electrode coating paste may be performed at the same time as the firing of the unit laminate 7. In this case, the conductor paste is applied to the opposite end of the unit laminate 7 and then fired. It is put into a furnace, and the firing of the unit laminate 7 and the firing of the external electrode coating paste are simultaneously performed.
[0031]
Although FIGS. 1 to 5 show the first green sheet 4 and the second green sheet 6 having a size corresponding to a single multilayer capacitor for convenience of explanation, the actual first green sheet 4 and the second green sheet 6 are shown in FIGS. The sheet 4 and the second green sheet 6 have a size that allows a large number of pieces, and the second green sheet 6 has a predetermined number of unfired internal electrode layers 5 corresponding to the number of pieces, such as m × n. Formed in an array. Further, the unfired laminate produced in the laminating step is divided into individual component sizes using a dicing apparatus or the like, whereby the unit laminate 7 shown in FIG. 3 is produced.
[0032]
As described above, the first and second green sheets 4 and 6 are water-based green sheets due to the cross-linking treatment by irradiation with the electron beam 3, but have a property of being hardly affected by environmental humidity. Therefore, when the first and second green sheets 4 and 6 are stacked and pressure-bonded, it is possible to reliably prevent a stacking shift due to deformation or elongation such as a thickness variation due to the influence of environmental humidity. Accordingly, a multilayer ceramic capacitor having the same quality as that obtained by using the organic solvent-based green sheet can be accurately manufactured by using the first and second green sheets 4 and 6 that are water-based green sheets. It is possible to accurately meet the demand for miniaturization and large capacity.
[0033]
Further, since the first and second green sheets 4 and 6 do not use an organic solvent as a slurry solvent as in the organic solvent-based green sheet, the working environment is contaminated by the organic solvent evaporated in the sheet manufacturing process or the like. The problem and the problem that the environment outside the factory is polluted by the organic solvent discharged from the factory can be avoided beforehand, the cost for taking measures against these problems is reduced, and the material cost related to the solvent is reduced. Thus, the sheet manufacturing cost and the unit price of the multilayer ceramic capacitor can be reduced.
[0034]
6 to 8 show the evaluation results of the water resistance of the green sheet manufactured by applying the present invention, respectively.
[0035]
Experimental Examples 1 to 16 in the evaluation results of FIG. 6 used a slurry containing barium titanate powder, water-soluble polyvinyl butyral, and water at a weight ratio of 70: 5: 25, and put this on a PET film by 5,50, Before the slurry coating is dried, the slurry is irradiated with an electron beam at a dose of 1, 10, 100, or 300 kGy to perform a crosslinking treatment, and then a drying treatment is performed to dry the slurry coating. Green sheets created by evaporating water are evaluated. Further, Comparative Examples 1 to 4 in the evaluation results of FIG. 6 used a slurry containing barium titanate powder, an organic solvent-based polyvinyl butyral, and alcohol at a weight ratio of 70: 5: 25, and put this on a PET film. , 50, 100, and 500 μm in thickness, and a green sheet created by drying the slurry coating is used as an evaluation target.
[0036]
In Experimental Examples 1 to 16 in the evaluation results of FIG. 7, a slurry containing barium titanate powder, water-soluble polyvinyl butyral, and water at a weight ratio of 70: 5: 25 was prepared, and this was placed on a PET film by 5,50. , 100, 500 μm in thickness, dried the slurry coating, irradiated with an electron beam at a dose of 1, 10, 100, 300 kGy to perform a cross-linking process, and evaluated a green sheet. I do. Comparative Examples 1 to 4 in the evaluation results of FIG. 7 used a slurry containing barium titanate powder, organic solvent-based polyvinyl butyral, and alcohol at a weight ratio of 70: 5: 25, and put this on a PET film. , 50, 100, and 500 μm in thickness, and a green sheet created by drying the slurry coating is used as an evaluation target.
[0037]
Experimental Examples 1 to 16 in the evaluation results of FIG. 8 used a slurry containing barium titanate powder, a water-soluble acrylic resin, and water at a weight ratio of 70: 5: 25, and put this on a PET film by 5,50, Before the slurry coating is dried, the slurry is irradiated with an electron beam at a dose of 1, 10, 100, or 300 kGy to perform a crosslinking treatment, and then a drying treatment is performed to dry the slurry coating. Green sheets created by evaporating water are evaluated. Further, Comparative Examples 1 to 4 in the evaluation results of FIG. 8 used a slurry containing barium titanate powder, an organic solvent-based acrylic resin, and alcohol at a weight ratio of 70: 5: 25, and put this on a PET film. , 50, 100, and 500 μm in thickness, and a green sheet created by drying the slurry coating is used as an evaluation target.
[0038]
In each case, the prepared green sheets were boiled in water, and the water resistance of each green sheet was evaluated based on the weight loss (%) after boiling.
[0039]
As can be seen from the evaluation results shown in FIGS. 6 to 8, the weight loss of each of Experimental Examples 1 to 16 was lower than that of Comparative Examples 1 to 4, and the water resistance of the aqueous green sheet was reduced by the crosslinking treatment. It can be seen that the water resistance of the solvent-based green sheet is generally improved. Further, as can be seen from the evaluation results shown in FIGS. 6 and 7, it is also found that the water resistance of the water-based green sheet is slightly improved when the crosslinking treatment is performed before drying the slurry applied material.
[0040]
In the above description, the invention relating to a ceramic green sheet and a method for manufacturing the same has been described in detail by taking a green sheet for a multilayer ceramic capacitor as an example, but the invention is not limited to other multilayer electronic components, for example, a multilayer ceramic inductor. It can also be applied to chip parts such as, array parts such as multilayer ceramic capacitor arrays, composite parts such as multilayer ceramic LC filters, and green sheets used when manufacturing multilayer substrates and the like, and similar effects can be obtained. it can. In the above description, the invention relating to the multilayer electronic component and the method of manufacturing the multilayer electronic component has been described in detail by taking a multilayer ceramic capacitor as an example. However, the present invention can be applied to the other multilayer electronic components described above, and similarly. The operation and effect of the present invention can be obtained.
[0041]
【The invention's effect】
INDUSTRIAL APPLICABILITY As described above in detail, according to the present invention, a ceramic green sheet which eliminates disadvantages of an aqueous green sheet and an organic solvent green sheet and can achieve total cost reduction, a method of manufacturing the same, a multilayer electronic component, and a method of manufacturing the same We can provide a method.
[Brief description of the drawings]
BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is an explanatory view of a step of producing a first green sheet. FIG. 2 is an explanatory view of a step of producing a second green sheet. FIG. 3 is an explanatory view of a step of producing a unit laminate. [Fig. 5]
Explanatory drawing of the preparation process of the external electrode [FIG. 6]
FIG. 7 shows the evaluation results of the water resistance of the green sheet.
FIG. 8 shows the evaluation results of the water resistance of the green sheet.
Figure showing the evaluation results of the water resistance of the green sheet.
DESCRIPTION OF SYMBOLS 1 ... Carrier film, 2 ... Slurry coating material, 3 ... Electron beam, 4 ... First green sheet, 5 ... Unfired internal electrode layer, 6 ... Second green sheet, 7 ... Unit laminate, 8 ... Unit chip, 9 ... internal electrodes, 10 ... external electrodes.

Claims (4)

A green sheet manufactured by applying a slurry containing at least a ceramic powder, a binder and a solvent onto an object to be coated,
The slurry uses a water-soluble resin as a binder, water is used as a solvent, and is subjected to a crosslinking treatment by electron beam irradiation after applying the slurry on an object to be coated,
A ceramic green sheet, characterized in that: A method for producing a green sheet by applying a slurry containing at least a ceramic powder, a binder and a solvent on an object to be coated,
Using a slurry using water as a solvent and water as a solvent, and applying a cross-linking treatment by irradiating an electron beam after applying the slurry on an object to be coated,
A method for producing a ceramic green sheet. A step of applying a slurry containing at least a ceramic powder, a binder and a solvent on a member to be coated to form a first green sheet; and a step of applying a conductor paste containing at least a metal powder, a binder and a solvent on the first green sheet. Manufacture using at least a step of preparing a second green sheet having an unfired conductor layer, and a step of stacking and pressing a large number of first green sheets and second green sheets in a predetermined order to form an unfired laminate A laminated electronic component,
A water-soluble resin is used as a binder and water is used as a solvent in the slurry in the first green sheet forming step, and the slurry is applied on an object to be coated and then subjected to a cross-linking treatment by electron beam irradiation.
A laminated electronic component characterized by the above-mentioned. A step of applying a slurry containing at least a ceramic powder, a binder and a solvent on a member to be coated to form a first green sheet; and a step of applying a conductor paste containing at least a metal powder, a binder and a solvent on the first green sheet. Laminating at least using a step of forming a second green sheet having an unfired conductor layer and a step of stacking and pressing a large number of the first green sheet and the second green sheet in a predetermined order to form an unfired laminate A method for manufacturing a mold electronic component,
In the first green sheet creating step, using a slurry using a water-soluble resin as a binder and water as a solvent, applying a slurry on a body to be coated and then irradiating with an electron beam to perform a crosslinking treatment;
A method for manufacturing a multilayer electronic component, comprising:

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