JP2005219963A - Ceramic slurry, method of manufacturing ceramic slurry, and ceramic green sheet, and method of manufacturing laminated ceramic electronic parts - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To obtain a ceramic slurry in which the dispersibility and dispersion stability of a ceramic powder is superior and from which a ceramic green sheet having good sheet characteristics can be manufactured. <P>SOLUTION: The ceramic slurry contains at least the ceramic powder, a dispersing agent, and a solvent, and the above-mentioned dispersing agent contains a first dispersing agent A comprising a polycarboxylic acid-based compound and a second dispersing agent B comprising a maleic anhydride-styrene copolymer to which a polyoxyalkylene group is introduced. And, the blending ratio B/A of the second dispersing agent B to the first dispersing agent A is 0.4 to 4 in weight ratio, and the total content of the first dispersing agent A and the second dispersing agent B is 0.6 to 2 pts.wt. to 100 pts.wt. of the ceramic powder. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a ceramic slurry, a method for producing a ceramic slurry, a ceramic green sheet, and a method for producing a multilayer ceramic electronic component.

  In recent years, multilayer ceramic electronic components such as multilayer inductors and multilayer ceramic capacitors have been increasingly required to be smaller and lighter and have higher density, and the ceramic green sheets constituting the ceramic multilayer body are also becoming thinner.

  By the way, this ceramic green sheet is usually produced by mixing a ceramic powder, a dispersant, a binder resin, and a solvent and wet-grinding to produce a ceramic slurry and subjecting the ceramic slurry to a forming process.

  And, the ceramic body obtained by firing the ceramic green sheet laminate is required to have good sinterability and excellent mechanical strength so as not to cause cracks, blisters, pores, etc. When the mixed state of the ceramic powder, the dispersant, the binder resin, and the solvent is non-uniform, sufficient sinterability cannot be obtained at a low temperature of 900 ° C. or lower.

  Therefore, conventionally, when the raw material powder is mixed with water as a solvent, an allyl alcohol maleic anhydride-styrene copolymer and polyoxyalkylene graft copolymer, or a polycarboxylic acid ammonium salt, or β is used as a dispersant. -Manufacture of oxide magnetic material that prevents disintegration of ceramic powders by adding ammonium salt of naphthalene sulfonic acid formalin condensate and improves dispersibility, thereby making the mixed state uniform A method has been proposed (Patent Document 1).

JP-A-7-130529

  However, when a graft copolymer of allyl alcohol maleic anhydride-styrene copolymer and polyoxyalkylene is added to the raw material powder as in Patent Document 1, the dispersibility is good and the dispersion stability is also good. However, since the sedimentation rate of the ceramic powder particles in the ceramic slurry is slow, there is a problem that the adsorption rate to the ceramic powder particles is slow and the dispersion treatment takes a long time.

  Further, in this case, the density of the ceramic green sheet becomes too high, and therefore, when an attempt is made to form a conductive pattern by screen printing on the ceramic green sheet, the solvent of the conductive paste hardly penetrates into the ceramic green sheet. There is a problem that printing bleeding occurs, and as a result, the electrode width becomes wider than the design value, which may cause deterioration of characteristics.

  Furthermore, when the above graft copolymer is used as a dispersant, the ceramic green sheet becomes hard. For this reason, when the ceramic green sheets on which the conductive pattern is formed are laminated and pressed, the conductive pattern is successfully placed in the ceramic green sheet. There is a problem that the conductor pattern cannot be embedded well and there is a possibility that the conductor pattern may be deformed or delaminated.

  On the other hand, when a polycarboxylic acid ammonium salt is used as the dispersant, the dispersion stability is poor, which increases the surface roughness of the ceramic green sheet and causes a problem of printability. Further, in this case, since the settling speed of the ceramic powder particles in the ceramic slurry is high, there is a problem that the quality of the ceramic green sheet is deteriorated when the sheet forming time of the ceramic slurry is long.

  Further, when polycarboxylic acid ammonium salt is used as a dispersant in this way, metal ions, particularly Cu ions, contained in the ceramic material are likely to elute, and when the metal ions are eluted, the ceramic slurry is gelled. There was a problem that it was difficult to manufacture green sheets.

  In addition, when an ammonium salt of β-naphthalene sulfonic acid formalin condensate is used as a dispersant, when mixed with a binder resin, the ceramic slurry gels, and as in the case of ammonium polycarboxylate, a ceramic green sheet There was a problem that it was difficult to manufacture.

  The present invention has been made in view of such problems, and is a ceramic slurry that is excellent in dispersibility and dispersion stability of ceramic powder and that enables the production of a ceramic green sheet having good sheet characteristics, and the ceramic slurry. It is an object of the present invention to provide a ceramic green sheet having good sheet characteristics and a method for manufacturing a multilayer ceramic electronic component such as a multilayer inductor using the ceramic green sheet.

  The inventors of the present invention have made extensive studies in order to achieve the above object. As a dispersant, a polycarboxylic acid compound and a maleic anhydride-styrene copolymer into which a polyoxyalkylene group has been introduced are used in combination. The present inventors have obtained the knowledge that a ceramic slurry that is excellent in dispersibility and dispersion stability of ceramic powder and enables production of a ceramic green sheet having good sheet characteristics can be obtained.

  The present invention has been made based on such knowledge, and the ceramic slurry according to the present invention is a ceramic slurry containing at least a ceramic powder, a dispersant, and a solvent, wherein the dispersant is a polysilica. It is characterized by containing a first dispersant composed of a carboxylic acid compound and a second dispersant composed of a maleic anhydride-styrene copolymer into which a polyoxyalkylene group has been introduced.

  Further, considering the dispersion stability of the ceramic slurry, the sheet characteristics of the ceramic green sheet, the printability, and the electrical characteristics of the multilayer ceramic electronic component, the blending ratio of the second dispersant to the first dispersant is The weight ratio is preferably 0.4-4.

  That is, the ceramic slurry of the present invention is characterized in that the mixing ratio of the second dispersant to the first dispersant is 0.4 to 4 by weight.

  Further, in order to effectively reduce the viscosity of the ceramic slurry and obtain a desired dispersion effect, the total content of the first dispersant and the second dispersant is 0.6 with respect to 100 parts by weight of the ceramic powder. ~ 2 parts by weight are preferred.

  That is, the ceramic slurry of the present invention is characterized in that the total content of the first dispersant and the second dispersant is 0.6 to 2 parts by weight with respect to 100 parts by weight of the ceramic powder.

  Further, when the content of the copper oxide is in the range of 8 to 16% in terms of mol%, the effect of dispersibility and dispersion stability becomes more remarkable.

  That is, the ceramic slurry of the present invention is characterized in that the ceramic powder contains a copper oxide, and the content of the copper oxide in the ceramic powder is 8 to 16% in mol%.

  The ceramic slurry is usually obtained by mixing ceramic powder, a solvent, a dispersing agent and other additives, and then wet-grinding. However, according to the research results of the present inventors, before adding the second dispersing agent. First, after adding only the first dispersant to the solvent, the ceramic powder is mixed and pulverized, and then the second dispersant is added and pulverized to obtain the viscosity before pulverization. The load on the pulverizer can be reduced and the handling becomes easy.

  Therefore, in the method for producing a ceramic slurry according to the present invention, the first dispersant composed of the polycarboxylic acid compound is added to the solvent, and then mixed with the ceramic powder to perform the first pulverization treatment, and then the polyoxy A ceramic slurry is produced by adding a second dispersing agent made of a maleic anhydride-styrene copolymer having an alkylene group introduced thereto and subjecting it to a second pulverization treatment.

  The ceramic green sheet according to the present invention is characterized in that the ceramic slurry is formed into a sheet by being processed.

  The method for manufacturing a multilayer ceramic electronic component according to the present invention includes a conductive pattern forming step of forming a conductive pattern on the surface of the ceramic green sheet, and a predetermined number of the ceramic green sheets on which the conductive pattern is formed are stacked. A laminated body forming step for forming a body, and a ceramic element body producing step for producing a ceramic element body by subjecting the laminated body to a firing process.

  According to the ceramic slurry, the first dispersant composed of a polycarboxylic acid compound and the second dispersant composed of a maleic anhydride-styrene copolymer into which a polyoxyalkylene group has been introduced are contained as a dispersant. Therefore, it is possible to avoid the elution of metal ions in the ceramic slurry, and to obtain good sheet characteristics, which makes it possible to obtain monolithic ceramic electronics with excellent dispersibility and dispersion stability of the ceramic powder. A ceramic slurry suitable for the production of parts can be obtained.

  Moreover, since the blending ratio of the second dispersant to the first dispersant is 0.4 to 4 by weight, good dispersion stability can be easily ensured, and sheet characteristics and A ceramic slurry having excellent printability can be obtained.

  In addition, by setting the content of the dispersant to 0.6 to 2 parts by weight with respect to 100 parts by weight of the ceramic powder, it is possible to effectively reduce the slurry viscosity of the ceramic slurry and obtain a desired dispersion effect.

  According to the method for producing a ceramic slurry of the present invention, the first dispersant composed of the polycarboxylic acid compound is added to the solvent, and then mixed with the ceramic powder to perform the first pulverization treatment, and then the polyoxyalkylene. The second dispersant made of a maleic anhydride-styrene copolymer having a group introduced therein is added and subjected to a second pulverization treatment to produce a ceramic slurry, so that the viscosity before the first pulverization treatment is lowered. Thus, the load on the pulverizer can be reduced, and the ceramic slurry can be easily manufactured.

  Further, according to the ceramic green sheet of the present invention, since the ceramic slurry is formed into a sheet by being processed, the ceramic powder is stably dispersed in the ceramic green sheet, and the sheet characteristics and printability are increased. Can be obtained.

  Further, according to the method for manufacturing a multilayer ceramic electronic component of the present invention, since the multilayer ceramic electronic component is manufactured using the ceramic green sheet, a multilayer ceramic electronic component having excellent electrical characteristics and excellent reliability can be obtained. Can be easily obtained.

  Next, an embodiment of the present invention will be described in detail.

The ceramic slurry as one embodiment of the present invention includes a ferrite raw material powder (ceramic powder) containing Fe ₂ O ₃ , NiO, CuO, ZnO and the like, a cellulose-based resin such as polyvinyl butyral resin and ethyl cellulose, an acrylic resin, Contains a binder resin such as vinyl acetate resin and polyvinyl alcohol resin, water as a solvent, and a dispersant, and if necessary, a plasticizer such as a phthalate ester or polyethylene glycol, or a wet such as a polyoxyalkylene monoalkyl ether Contains the agent.

  The ceramic slurry includes, as the dispersant, a first dispersant A composed of a polycarboxylic acid compound and a second dispersant composed of a maleic anhydride-styrene copolymer into which a polyoxyalkylene group has been introduced. B is used together.

  That is, from the viewpoint of preventing the ferrite raw material powders from agglomerating and improving dispersibility, it is necessary to contain a dispersant in the ceramic slurry. Such polycarboxylic acid compounds are used.

  However, this polycarboxylic acid-based compound has good adsorption to the ferrite raw material powder, and although it can ensure an appropriate sheet density when a ceramic green sheet is produced, the metal ions contained in the ferrite raw material powder In particular, Cu ions are likely to elute, and the ceramic slurry may gel, making it difficult to produce a ceramic green sheet.

  Moreover, since the sedimentation rate of the ceramic powder particles in the ceramic slurry is fast and the dispersion stability is poor, the sheet properties deteriorate such as deterioration of the surface roughness and reduction of the sheet elongation rate when the sheet forming time becomes long, and the printability deteriorates. May be incurred.

  On the other hand, the maleic anhydride-styrene copolymer having a polyoxyalkylene group introduced can suppress elution of metal ions, but the adsorption to the ferrite raw material powder is poor, the sheet density increases, and the ceramic green sheet As a result, the surface roughness of the ink becomes large and printing bleeding or the like is likely to occur, resulting in a decrease in printability.

  Therefore, in the present ceramic slurry, as the dispersant, the first dispersant A composed of a polycarboxylic acid compound and the second dispersant composed of a maleic anhydride-styrene copolymer containing a polyoxyalkylene group are used in combination. doing.

  And in this Embodiment, the 1st dispersing agent A and the 2nd so that the mixture ratio B / A of the 2nd dispersing agent B with respect to the 1st dispersing agent A may be 0.4-4 by weight ratio. Dispersant B is blended.

  That is, when the blending ratio B / A is less than 0.4 by weight, the blending amount of the first dispersant A in the dispersant becomes excessive, and the effect of adding the first dispersant A becomes dominant. For this reason, if the sedimentation rate of the slurry is increased to deteriorate the dispersion stability, and the sheet forming time is prolonged, the sheet characteristics may be deteriorated.

  On the other hand, when the blending ratio B / A exceeds 4, the content of the second dispersant B in the dispersant becomes excessive, and the effect of adding the second dispersant B becomes dominant, and the ceramic There is a possibility that the density of the green sheet becomes high and printing bleeding occurs, resulting in deterioration of printability.

  Therefore, in the present embodiment, the first dispersant A and the second dispersant B are blended so that the blend ratio B / A is 0.4 to 4 by weight.

  The total content of the first and second dispersants A and B is 0.6 to 2 parts by weight with respect to 100 parts by weight of the ferrite raw material powder.

  That is, when the total amount of the first and second dispersants A and B is less than 0.6 parts by weight with respect to 100 parts by weight of the ferrite raw material powder, the effect of adding the dispersant can be sufficiently exhibited. The dispersibility of the ceramic powder particles is deteriorated and the viscosity of the slurry is increased. On the other hand, the total content of the first and second dispersants A and B is 2 weights per 100 parts by weight of the ferrite raw material powder. When it exceeds the part, the ceramic powder particles are aggregated, and the slurry viscosity may be increased.

  Therefore, the total content of the first and second dispersants A and B is 0.6 to 2 parts by weight with respect to 100 parts by weight of the ferrite raw material powder.

  First, the molecular weight of the dispersant A is preferably 1,000 to 20,000, and the molecular weight of the second dispersant B is preferably 10,000 to 100,000.

  That is, the larger the molecular weight of the dispersant, the more difficult the slurry settles and the dispersion stability increases. Therefore, the molecular weight is at least 1,000 or more for the first dispersant A and for the second dispersant B. Is preferably at least 10,000. However, when the molecular weight of the first dispersant A exceeds 20,000 and the molecular weight of the second dispersant B exceeds 100,000, the first and second dispersants A and B are adsorbed on the ceramic powder. This makes it difficult to reduce the slurry viscosity and reduces the grinding efficiency during wet grinding.

  Therefore, as described above, it is preferable to use a dispersant A having a molecular weight of 1,000 to 20,000, and a second dispersant B having a molecular weight of 10,000 to 100,000. It is preferable to use one.

  Next, the manufacturing method of this ceramic slurry is explained in full detail.

_First, Fe ₂ O 3: _45~50 mol%, NiO: 5 to 50 mol%, ZnO: 0.5 to 30 mol%, CuO: such that 8-16 _{mol%, Fe 2 O 3, NiO} , Weigh ZnO and CuO.

The reason why Fe ₂ O ₃ , NiO, ZnO and CuO were weighed so as to have the above-mentioned composition ratio is as follows.

That is, when the content of Fe ₂ O ₃ is less than 45 mol%, the initial magnetic permeability and the inductance are too small, and the Q value is also lowered. On the other hand, the content of Fe ₂ O ₃ exceeds 50 mol%. This is because the sintered density after firing the ceramic green sheet decreases and moisture and plating solution enter, which may lead to a decrease in reliability. Further, when NiO is less than 5 mol%, the Curie temperature is 100 ° C. or less, and when NiO exceeds 50 mol%, the inductance is reduced. Further, when ZnO is less than 0.5 mol%, the inductance is lowered, and when it exceeds 30 mol%, the Curie temperature is 100 ° C. or less.

  Moreover, if CuO is less than 8 mol% or exceeds 16 mol%, the effect of adding the dispersant of the present invention is reduced, and good and stable dispersibility cannot be obtained.

  Next, these weighed materials are put into a medium-type pulverizer such as a ball mill or a sand mill, mixed, and sufficiently wet-pulverized. Next, the wet-pulverized mixture is dried and pulverized again, and then calcined to obtain a calcined powder.

  Next, the calcined powder is again put into a medium-type pulverizer and wet pulverized, and then dried to obtain a ferrite powder (ceramic powder).

  Next, after adding water as a solvent to the first dispersant A in a medium-type pulverizer, the ferrite powder is put into the medium-type pulverizer to perform a first pulverization process, followed by wet pulverization Then, the second dispersing agent B is added to perform the second pulverization treatment, and the wet pulverization is sufficiently performed again. The time required for the first pulverization process and the time required for the second pulverization process are appropriately set according to the amount and particle size of the ferrite powder charged into the medium-type pulverizer, for example, the first pulverization process. The process is set to 1 hour and the second grinding process is set to 11 hours.

  The dispersant is 0.6 to 2 parts by weight in total with respect to 100 parts by weight of the ferrite powder, and the blending ratio B / A of the second dispersant B to the first dispersant A is 0.4 to 4. The first and second dispersants A and B are weighed so that

  Next, the wet pulverized product is mixed with a binder such as polyvinyl butyral resin, cellulose resin, vinyl acetate resin, polyvinyl alcohol resin, a plasticizer such as dibutyl phthalate, and a wetting agent such as polyoxyalkylene monoalkyl ether, and wet pulverized. This produces a ceramic slurry.

  Thus, in this embodiment, since the first dispersant A is first added to water as a solvent and then mixed with the ferrite powder, the viscosity before pulverization can be reduced. The load is reduced and handling becomes easy.

  That is, the polycarboxylic acid ammonium salt that is the first dispersant A has a relatively small molecular weight and a large number of hydrophilic groups, so that it has good solubility in water as a solvent. Therefore, the ferrite powder, the first dispersant The viscosity of the mixture containing A and water is low. On the other hand, the maleic anhydride-styrene copolymer having a polyoxyalkylene group introduced as the second dispersant B has a higher molecular weight than the first dispersant A and has a higher proportion of hydrophobic groups. Solubility is low. Therefore, when the second dispersant B is mixed in the above mixture, the viscosity becomes high.

  However, since the ferrite powder is mixed with the water to which the first dispersant A is added as in the present embodiment and the first pulverization process is performed in a state of low viscosity, the first pulverization is performed. In the pulverization process, the pulverization process can be performed with a light load, and then the second dispersant B is added, the second pulverization process is performed, and the wet pulverization is sufficiently performed again to facilitate the pulverization process. it can.

  Note that the pulverization process can be facilitated by dividing the pulverization process into the first pulverization process and the second pulverization process as described above, but the quality of the final product ceramic slurry can be improved. Therefore, there is a case where the first dispersant A and the second dispersant B prepared at a predetermined blending ratio are added to water and then mixed with the ferrite powder to perform one wet process. You may make it manufacture a ceramic slurry by a grinding | pulverization.

  The ceramic slurry thus obtained is defoamed by depressurization, and then the ceramic slurry is applied onto a film such as polyethylene terephthalate (PET) that has been subjected to a mold release treatment, and then molded by a doctor blade method or the like. The ceramic green sheet is manufactured by processing.

  And since the ceramic green sheet obtained in this way has good dispersion stability of the ceramic powder, it is suitable as a ceramic green sheet for multilayer ceramic electronic components.

  Next, a method for manufacturing a multilayer inductor as a multilayer ceramic electronic component using the ceramic green sheet will be described in detail.

  FIG. 1 is a perspective view schematically showing an embodiment of a multilayer inductor as a multilayer ceramic electronic component manufactured using the ceramic green sheet. In the multilayer inductor, a coil conductor 2 is embedded in a ceramic body 1, and external electrodes 3 a and 3 b are formed at both ends of the ceramic body 1. The coil conductor 2 is formed in a spiral shape so that the coil patterns 4 to 7 can be electrically connected via the via holes 8 to 10, and the lead portion 4a of the coil pattern 4 is electrically connected to the external electrode 3a. The lead portion 7a of the coil pattern 7 is electrically connected to the external electrode 3b.

  This multilayer inductor is manufactured as follows.

  First, the ceramic green sheet obtained as described above is cut into predetermined dimensions, and magnetic sheets 11 to 15 are prepared as shown in FIG. Next, via holes 8 to 10 are drilled at predetermined positions of the magnetic sheets 12 to 14 with a laser processing machine, and then U-shaped on the surfaces of the magnetic sheets 12 to 15 so that the coil conductor 2 can be formed. The coil patterns 4 to 7 are formed. The lead portion 4 a of the coil pattern 4 and the lead portion 7 a of the coil pattern 7 are formed along the end portions of the magnetic sheets 12 and 15. Subsequently, after laminating | stacking the magnetic material sheets 11-15, it press-bonds, a laminated body is formed, the baking process including a binder removal process is given to this laminated body, and the ceramic body 1 is formed. Next, a conductive paste is applied to both ends of the ceramic body 1, and a baking process is performed, whereby a multilayer inductor is manufactured.

  Since the multilayer inductor formed in this way is manufactured using ceramic green sheets with good dispersibility and excellent dispersion stability, a multilayer inductor with good electrical characteristics and excellent reliability can be obtained. Can do.

  Next, examples of the present invention will be specifically described.

First, Fe ₂ O ₃ , ZnO, NiO, and CuO were weighed so that Fe ₂ O ₃ : 47.5 mol%, ZnO: 15.5 mol%, NiO: 23.0 mol%, CuO: 14.0 mol%, respectively. These weighed products were put into a ball mill and mixed and pulverized by wet for 15 hours. The mixture is then dried and pulverized, calcined at a temperature of 750 ° C. for 1 hour to prepare a calcined powder, and the calcined product is placed in a ball mill and pulverized wet for 15 hours and then pulverized. A ferrite powder was obtained.

  Next, with respect to 100 parts by weight of the ferrite powder, water as a solvent: 80 parts by weight, polycarboxylic acid ammonium salt as the first dispersant A: 0.5 part by weight, and the polyol as the second dispersant B Maleic anhydride-styrene copolymer introduced with xylene groups: 0.8 part by weight (total dispersant content: 1.3 parts by weight) was put into a ball mill, and finally 100 parts by weight of the ferrite powder was put into the ball mill. The mixture was pulverized for 12 hours in a wet manner, and the ferrite powder was dispersed in water to which a dispersant was added.

  Next, acrylic binder resin: 14 parts by weight, dibutyl phthalate as a plasticizer: 0.7 parts by weight, polyoxyethylene as a wetting agent with respect to 100 parts by weight of the ferrite powder thus added with a dispersant. Polyoxypropylene nonylphenyl ether: 0.7 part by weight was added, mixed and pulverized in a ball mill for 12 hours by wet, and then defoamed under reduced pressure to obtain a ceramic slurry.

  Here, the slurry was placed in a 10 mL measuring cylinder and allowed to stand for 24 hours, and the presence or absence of sedimentation of the slurry was visually confirmed.

  Next, this ceramic slurry was applied to a peelable plastic film in the form of a film by a doctor blade method and dried to produce a long ceramic green sheet having a film thickness of 25 μm.

  Here, sheet characteristics of the ceramic green sheet, that is, sheet density, surface roughness Ra, sheet strength, and sheet elongation were measured.

  The sheet density was obtained by punching out a ceramic green sheet in a length of 58.4 mm and a width of 76.4 mm, and measuring the weight and volume of the punched ceramic green sheet.

  The surface roughness Ra was determined by observing the punched ceramic green sheet with an atomic force microscope.

  For the sheet strength, both ends of the punched ceramic green sheet are fixed to a chuck set at a chuck interval of 10 mm of a tensile tester, both ends are pulled at 10 mm / min, and the maximum value of the tensile force immediately before cutting is measured. Was determined by

  The sheet elongation was calculated by dividing the elongation at the time of measuring the sheet strength by the chuck interval (10 mm).

  Next, using a laser processing machine, drill a through hole to be a via hole at a predetermined position of the ceramic green sheet, and then screen-print the ceramic green sheet with a conductive paste mainly composed of an Ag alloy, Heat drying was performed to form a coil pattern having a thickness of 20 μm.

  The design value of the electrode width was 80 μm, and the printability was evaluated by measuring the electrode width of the coil pattern.

Next, the ceramic green sheet on which the coil pattern is formed is cut into a predetermined size, 11 ceramic green sheets are laminated so that the coil conductor can be formed, and the upper and lower sides of the ceramic green sheet are not formed with the coil pattern. After sandwiching between the sheets, thermocompression bonding was performed at a temperature of 45 ° C. and a pressure of 9.8 × 10 ⁷ Pa, followed by cutting to produce a ceramic laminate having a length of 1.0 mm, a width of 0.5 mm, and a thickness of 0.5 mm.

  Here, the thickness of the ceramic laminate before and after pressure bonding was measured, and (thickness before pressure bonding−thickness after pressure bonding) / thickness before pressure bonding × 100 was calculated to determine the pressure bonding rate.

  Next, this ceramic laminate is heated in a low oxygen atmosphere at a temperature of 500 ° C. for 2 hours to burn and remove the binder resin contained in the ceramic laminate, and then fired in the atmosphere at a temperature of 880 ° C. for 150 minutes. The ceramic sintered compact was produced.

  Next, the ceramic sintered body was subjected to barrel polishing, and the corner portion was processed into an R shape to form a ceramic body.

  Next, a conductive paste containing Ag as a main component is applied to both ends of the ceramic body by an immersion method, dried at a temperature of 100 ° C. for 10 minutes, and then baked at a temperature of 780 ° C. for 15 minutes. The multilayer inductor of Example 1 having a 5-turn coil conductor was produced.

  Next, an impedance analyzer (HP 4291A, manufactured by Hewlett-Packard Company) was used to measure impedance at 100 MHz.

  Further, a ceramic slurry blended so as to be 1.0 part by weight of the first dispersant A (polycarboxylic acid ammonium salt) with respect to 100 parts by weight of the ferrite powder was prepared, and in the same manner as in Example 1. The presence or absence of sedimentation of the ceramic slurry was visually confirmed. In addition, a ceramic green sheet was prepared for this ceramic slurry using a doctor blade method, and the sheet characteristics of the ceramic green sheet (sheet density, surface roughness Ra, sheet strength, and Sheet elongation) was measured. Next, a coil pattern was formed on the ceramic green sheet by the same method and procedure as in Example 1, printability was evaluated, and the crimping ratio in the ceramic laminate was calculated. And the multilayer inductor of the comparative example 1 was produced with the method and procedure similar to Example 1, and the impedance in 100 MHz was measured.

  Further, a ceramic slurry was prepared by blending the second dispersant B (maleic anhydride-styrene copolymer having a polyoxyalkylene group introduced): 1.6 parts by weight with respect to 100 parts by weight of the ferrite powder. The presence or absence of sedimentation of the ceramic slurry was visually confirmed by the same method as in Example 1. In addition, a ceramic green sheet was prepared for this ceramic slurry using a doctor blade method, and the sheet characteristics of the ceramic green sheet (sheet density, surface roughness Ra, sheet strength, and Sheet elongation) was measured. Next, a coil pattern was formed on the ceramic green sheet by the same method and procedure as in Example 1, printability was evaluated, and the crimping ratio in the ceramic laminate was calculated. And the multilayer inductor of the comparative example 2 was produced by the method and procedure similar to Example 1, and the impedance in 100 MHz was measured.

この表１から明らかなように比較例１は、分散剤として、第１の分散剤Ａのみを使用しているため、２４時間放置後のセラミックスラリーに沈降が認められ、分散の安定性が悪いことが分かった。また、シート密度やシート強度、圧着率は良好であり、電極幅も８３．２μｍであり設計値（８０μｍ）と比べて差異も小さく、印刷性も良好であるが、表面粗さＲａが０．１５２μmと大きく、また伸び率が９％と低く、したがって、セラミックグリーンシートは表面が粗くて硬く、積層インダクタのインピーダンスが５５０μｍと低かった。これは、セラミックグリーンシートの表面が粗く硬いため、セラミックグリーンシートを積層して圧着した際、コイルパターンがセラミックグリーンシート中に埋め込まれずに変形したためと考えられる。 Table 1 shows the presence / absence of slurry sedimentation, sheet characteristics (sheet density, sheet surface roughness Ra, sheet strength, sheet elongation), coil width of the coil pattern, pressure bonding ratio, and impedance of each example and comparative example. .

As is apparent from Table 1, since Comparative Example 1 uses only the first dispersant A as the dispersant, sedimentation is observed in the ceramic slurry after being left for 24 hours, and the dispersion stability is poor. I understood that. Further, the sheet density, sheet strength, and pressure bonding ratio are good, the electrode width is 83.2 μm, the difference is small compared to the design value (80 μm), and the printability is good, but the surface roughness Ra is 0.1. The ceramic green sheet was rough and hard, and the impedance of the multilayer inductor was as low as 550 μm. This is presumably because the surface of the ceramic green sheet was rough and hard, and therefore, when the ceramic green sheets were laminated and pressed, the coil pattern was deformed without being embedded in the ceramic green sheet.

In Comparative Example 2, since only the second dispersant B is used as the dispersant, the ceramic slurry does not settle and the dispersion stability is good, but the sheet density is 2.89 × 10. ^Since it was as large as ³ kg / m ³ , printing bleeding occurred when forming a coil pattern by screen printing, the surface roughness Ra was as large as 0.163 μm, the electrode width was 90.8 μm, and the printability deteriorated. Also, the crimping rate is as low as 10% and the sheet strength is as large as 3.4 × 10 ⁵ Pa. Therefore, when the ceramic green sheets are laminated and crimped, the coil pattern is deformed without being embedded in the ceramic green sheet, For this reason, the impedance of the multilayer inductor was as low as 500 μm.

  On the other hand, Example 1 uses the first dispersant A and the second dispersant B in combination as the dispersant, so that the slurry does not settle even when left for 24 hours, and the dispersion stability is high. It was found that the surface roughness Ra was 0.115 μm and became finer, the sheet elongation rate was improved, the crimping rate and the printability (electrode width) were also good, and the impedance of the multilayer inductor was improved. .

  As shown in Table 2, the dispersant was prepared so that the blending ratio A / B of the first dispersant A and the second dispersant B was different (the total content of the dispersant was 100 parts by weight of ferrite powder). 1.3 parts by weight), each slurry was used, and ceramic slurry, ceramic green sheet, ceramic green sheet, and multilayer inductor were prepared by the same method and procedure as in [Example 1]. The characteristics (sheet density, sheet strength, sheet elongation), electrode width, pressure bonding ratio, and impedance at 100 MHz were appropriately measured.

この表２から明らかなように試料番号１は配合比率Ｂ／Ａが６であり、第１の分散剤Ａに対する第２の分散剤Ｂの配合量が過剰となって第２の分散剤Ｂの添加効果が支配的となり、したがってセラミックスラリーの沈降は生じず分散の安定性は良好であるが、シート密度が２．８６×１０^３ｋｇ／ｍ^３と大きく、このためスクリーン印刷によるコイルパターン形成時に印刷滲みが発生し、電極幅が９０．０μｍとなって印刷性が悪化している。しかも、圧着率が１０％と低く、シート強度も３．３×１０^５Ｐａと大きくシートが硬いため、セラミックグリーンシートを積層して圧着した際、コイルパターンがセラミックグリーンシート中に埋め込まれずにコイルパターンが変形し、このため積層インダクタのインピーダンスが５００μｍと低くなる。 Table 2 shows the results.

As apparent from Table 2, Sample No. 1 has a blending ratio B / A of 6, and the blending amount of the second dispersant B with respect to the first dispersant A is excessive, so that the second dispersant B The effect of addition becomes dominant, so that the ceramic slurry does not settle and the dispersion stability is good. However, the sheet density is as high as 2.86 × 10 ³ kg / m ^3, and therefore, when forming a coil pattern by screen printing. Printing blur occurs, and the electrode width is 90.0 μm, and the printability is deteriorated. Moreover, since the pressure bonding rate is as low as 10% and the sheet strength is as large as 3.3 × 10 ⁵ Pa and the sheet is hard, the coil pattern is not embedded in the ceramic green sheet when the ceramic green sheets are laminated and bonded. The pattern is deformed, so that the impedance of the multilayer inductor is as low as 500 μm.

  Sample No. 5 has a blending ratio B / A of 0.2, and the blending amount of the second dispersant B with respect to the first dispersant A is so small that the effect of adding the first dispersant A is small. As a result, the ceramic slurry settles and the dispersion stability is poor. In addition, since the elongation is as low as 9%, when the ceramic green sheets are laminated and bonded, the coil pattern is not embedded in the ceramic green sheet and the coil pattern is deformed. Therefore, the impedance of the laminated inductor is as low as 560 μm. .

  On the other hand, Sample Nos. 2 to 4 have a blending ratio B / A in the range of 0.5 to 4, good dispersion stability, and improved sheet elongation. The electrode width was also good, and it was found that the impedance of the multilayer inductor was improved.

  By the same method and procedure as in Example 1, as shown in Table 4, ceramic slurries of Sample Nos. 11 to 18 having different total contents of the dispersant were prepared, and the slurry viscosity was measured with a viscometer. The blending ratio B / A of the first dispersant A and the second dispersant B was 1.6.

試料番号１１は、含有量総計がフェライト粉末１００重量部に対して０．４重量部と過少であるため、フェライト粉末の溶媒中での分散が悪く、スラリー粘度は６００ｍＰａ・ｓとが高くなっている。 Table 3 shows the total content of each sample and the slurry viscosity.

Sample No. 11 has a total content of 0.4 parts by weight with respect to 100 parts by weight of ferrite powder, so the dispersion of ferrite powder in the solvent is poor and the slurry viscosity is as high as 600 mPa · s. Yes.

  In Sample Nos. 17 and 18, the total amount of the particles is excessive, such as 3.0 parts by weight and 5.0 parts by weight with respect to 100 parts by weight of the ferrite powder. Therefore, the slurry viscosities are as high as 500 mPa · s and 800 mPa · s, respectively.

  On the other hand, Sample Nos. 12 to 16 have a total content of 0.6 to 2.0 parts by weight with respect to 100 parts by weight of the ferrite powder, so that the slurry viscosity is 220 to 300 mPa · s, respectively. It has been found that a slurry viscosity suitable for the ceramic slurry can be obtained.

  First, a ferrite powder having the same blending ratio B / A as in Example 1 was prepared. Next, with respect to 100 parts by weight of the ferrite, 0.5 parts by weight of polycarboxylic acid ammonium salt as the first dispersant A: 80 parts by weight of water as a solvent is mixed in a ball mill, and then the ferrite powder 100 is mixed. The viscosity was measured after the parts by weight were put into a ball mill and mixed. After that, the wet pulverization is performed for 1 hour (first pulverization), and then the maleic anhydride-styrene copolymer into which the polyoxylene group as the second dispersant B is introduced: 0.8 part by weight Were put into a ball mill, mixed, and pulverized in a wet manner for 11 hours (second pulverization process).

  Next, using the same method and procedure as in [Example 1] for the ferrite powder containing the dispersant as described above, a ceramic slurry was prepared, and the slurry viscosity (viscosity after pulverization) was measured.

  Next, this ceramic slurry was applied to a peelable plastic film in the form of a film by a doctor blade method and dried to produce a long ceramic green sheet having a film thickness of 25 μm, as in [Example 1]. By this method, the sheet density, surface roughness Ra, sheet strength, and sheet elongation of the ceramic green sheet were measured.

  Next, the ceramic laminated body of Example 11 was produced by the same method and procedure as [Example 1], and the press bonding ratio was obtained.

  Table 4 shows the viscosity before and after grinding, sheet characteristics (sheet density, surface roughness Ra, sheet strength, sheet elongation), and pressure bonding ratio.

実施例１１及び比較例１１共、シート特性（シート密度、表面粗さＲａ、シート強度、シート伸び率）、及び圧着率は略同様であるが、実施例１１は比較例１１に比べて粉砕前の粘度が低く、これにより粉砕機の負荷を軽減することができ、取り扱いが容易になることが確認された。 In Table 4, as a comparative example, the viscosity before and after pulverization in the manufacturing process of the multilayer inductor of Example 1 is measured, and the measurement result is also described (Comparative Example 11).

Both Example 11 and Comparative Example 11 have substantially the same sheet characteristics (sheet density, surface roughness Ra, sheet strength, sheet elongation), and pressure-bonding rate, but Example 11 is before pulverization compared to Comparative Example 11. It was confirmed that the viscosity of the pulverizer was low, which could reduce the load on the pulverizer and facilitated handling.

It is a perspective view showing one embodiment of a multilayer inductor as a multilayer ceramic electronic component manufactured by the manufacturing method of the present invention. It is a perspective view for demonstrating the manufacturing method of the multilayer inductor of this invention.

Explanation of symbols

4-7 Coil pattern (conductive pattern)
11-15 ceramic green sheet

Claims (7)

A ceramic slurry containing at least a ceramic powder, a dispersant, and a solvent,
The dispersant contains a first dispersant made of a polycarboxylic acid compound and a second dispersant made of a maleic anhydride-styrene copolymer having a polyoxyalkylene group introduced. Characteristic ceramic slurry.   The ceramic slurry according to claim 1, wherein a mixing ratio of the second dispersant to the first dispersant is 0.4 to 4 by weight.   The total content of the first dispersant and the second dispersant is 0.6 to 2 parts by weight with respect to 100 parts by weight of the ceramic powder. Ceramic slurry.   The ceramic powder contains a copper oxide, and the content of the copper oxide in the ceramic powder is 8 to 16% by mol%. The ceramic slurry described in 1.   A first dispersant composed of a polycarboxylic acid compound is added to a solvent, mixed with a ceramic powder, subjected to a first grinding treatment, and then a maleic anhydride-styrene copolymer having a polyoxyalkylene group introduced therein. A method for producing a ceramic slurry, comprising: adding a second dispersant composed of a coalescence and performing a second pulverization treatment to produce a ceramic slurry.   A ceramic green sheet, wherein the ceramic slurry according to any one of claims 1 to 4 is formed and formed into a sheet shape.   A conductive pattern forming step of forming a conductive pattern on a surface of the ceramic green sheet according to claim 6, a laminate forming step of forming a laminate by laminating a predetermined number of ceramic green sheets on which the conductive pattern is formed, and A method of manufacturing a multilayer ceramic electronic component, comprising: a ceramic body manufacturing step of performing a firing process on a multilayer body to manufacture a ceramic body.

Images