JP2006062910A - Ceramic composition, ceramic green sheet using the same and ceramic sintered compact - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic composition capable of precisely adjusting the density of a green sheet by a simple method that a small quantity of an organic gelling agent is added to ceramic slurry, the ceramic green sheet using the same and a ceramic sintered compact. <P>SOLUTION: The ceramic composition is prepared by adding the organic gelling agent comprising a polysaccharide derivative having ≥0.1 mgKOH/g acid value into the ceramic slurry containing a polyvinyl acetal resin as a resin binder. The ceramic green sheet containing ceramic powder having 0.1-10 μm average particle diameter is manufactured using the ceramic composition and fired to obtain the ceramic sintered compact having ≥95% relative density. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention adjusts the density of a ceramic green sheet to be obtained by adding an organic gelling agent to a ceramic slurry, a ceramic green sheet using the ceramic composition, and a ceramic sintered body using the ceramic composition About.

  Conventionally, as an application of a ceramic sintered body manufactured by a method of laminating and firing a plurality of ceramic green sheets, for example, an electronic component storage package for storing semiconductor elements such as LSI and various electronic components, Examples thereof include electronic parts such as multilayer ceramic capacitors, and piezoelectric parts using piezoelectric materials.

  For example, in the case of an electronic component housing package, such a ceramic sintered body is configured such that a metallized wiring layer is disposed on the surface or inside of an insulator in which a plurality of insulating layers are stacked. Insulating layers are often made of ceramics such as alumina ceramics, and more recently, insulating layers made of laminated glass ceramics that can be fired simultaneously with copper metallization are also put into practical use. Has been.

  In the production of such a ceramic sintered body, a ceramic slurry (hereinafter also referred to as a slurry) is prepared by adding an appropriate resin binder to a ceramic raw material powder prepared at a predetermined ratio and dispersing it in an aqueous or non-aqueous solvent. A ceramic green sheet having a predetermined thickness (hereinafter also referred to as a green sheet) is formed by a conventionally known casting method such as a doctor blade method or a lip coater method.

  Next, as a metallized wiring layer, a metal paste obtained by adding and mixing a resin binder, a solvent, and a plasticizer to an appropriate metal powder is printed and applied to a pattern of a predetermined shape on the above green sheet by a well-known screen printing method At the same time, a through hole (through hole) is formed by a micro drill or a laser, and a metal paste is filled in the through hole to form a through conductor (via conductor, via hole).

  Finally, a ceramic sintered body is obtained by firing a green sheet laminated body obtained by laminating a plurality of obtained green sheets by a method using an appropriate adhesion liquid or a technique such as thermocompression bonding under predetermined conditions.

  In such a ceramic sintered body manufacturing process, if the density of the green sheet to be used is not uniform, the difference in green sheet workability due to local differences in the strength and elongation of the green sheet, and the lamination Since the amount of shrinkage varies in the post-firing step, it causes deformation or cracks in the obtained ceramic sintered body and causes the metallized wiring layer to break. Moreover, when the obtained ceramic sintered body has a density variation, required characteristics such as dimensional accuracy and strength may be partially impaired.

  On the other hand, since the green sheet is becoming thinner with the downsizing of the ceramic sintered body, the ratio of the level difference generated when the electrodes and the like are provided on the green sheet tends to increase. If this level difference cannot be absorbed at the time of stacking, it may cause delamination between layers due to stacking failure.

In order to solve these problems, it is necessary to accurately adjust the green sheet density before firing. For example, a method is disclosed in which a green sheet is pressed to obtain a predetermined density (for example, Patent Document 2). Also disclosed is a method for adjusting the shrinkage rate of the green sheet by immersing the green sheet in a hot water bath to shrink a resin binder made of polyvinyl butyral (hereinafter also referred to as butyral) which is a kind of polyvinyl acetal resin. (For example, Patent Document 3). On the other hand, a method of adjusting the green sheet density by controlling the shrinkage of the resin binder during the solvent drying step by changing the ratio of the good solvent and the poor solvent to the resin binder in the ceramic slurry is disclosed (for example, Patent Document 4, Non-Patent Document 1). Furthermore, a method of adjusting the green sheet density with an additive such as a polyhydric alcohol having polarity that is not compatible with the resin binder and compatible with the ceramic slurry is disclosed (for example, Patent Document 5).
JP 2003-318541 A JP-A-8-133847 JP-A-3-237798 JP-A-8-217546 JP 2004-168642 A JP 2004-143008 A JP-A-8-277302 “Advanceds in ceramics”, Vol. 21, Ceramic Powder Science pp. 495-515, 1987

  However, in the case of Patent Document 2, the green sheet density often does not increase linearly even when the press pressure is increased, and there is a limit in controlling the green sheet density.

  In the case of Patent Document 3, it is difficult to control the contraction rate of the green sheet in the horizontal direction and the vertical direction.

  On the other hand, the density adjusting method using the solvent drying process shown in Patent Document 4 and Non-Patent Document 1 is a green sheet using a good solvent having a high solubility in the resin binder, because the shrinkage is large, and the density is high. On the other hand, if a poor solvent with low solubility in the resin binder is used, the deformation resistance of the slurry increases, shrinkage during the drying process decreases, and many pores (pores) are formed. This is because the sheet density is lowered. That is, the green sheet density can be controlled by changing the types and amounts of the good solvent and the poor solvent in the slurry. However, in order to accurately adjust the density, it is necessary to prepare several types of slurries with different types and amounts of good and poor solvents. It was difficult to carry out efficient production because it was necessary to change the drying conditions in accordance with the pressure, evaporation rate index, boiling point, and the like. In addition, when a large amount of poor solvent is used, relatively large pores are locally formed, resulting in variations in the powder packing density distribution of the green sheet, resulting in local differences in the strength and elongation of the green sheet. There was a problem that the workability of the green sheet was lowered and the required characteristics such as dimensional accuracy and strength of the ceramic sintered body obtained after firing were partially impaired.

  Furthermore, in the case of Patent Document 5, in the method of reducing the density using phase separation in the drying process of the green sheet, since the additive having polarity is used, the density can be adjusted without impairing the dispersibility. However, in order to efficiently adjust the density, it is necessary to add an additive that is not compatible with the resin binder as much as 20 to 180% by weight with respect to the resin binder. There is a risk of destabilization and possibly a decrease in dispersibility. In addition, in order to adjust the density by phase separation with high accuracy, it is necessary to prepare several types of slurries with different types and amounts of additives and solvents, and thus it is difficult to perform efficient production. .

  Accordingly, the present invention has been completed in view of the above problems, and its purpose is to accurately adjust the density of the green sheet by a simple method of adding a small amount of an organic gelling agent to the ceramic slurry. It is to provide a ceramic composition that can be produced, and a ceramic green sheet using the ceramic composition, and a ceramic sintered body.

  The ceramic composition of the present invention is obtained by adding an organic gelling agent composed of a polysaccharide derivative having an acid value of 0.1 mgKOH / g or more to a ceramic slurry containing ceramic powder and a resin binder. .

  In the ceramic composition of the present invention, preferably, the resin binder contains a polyvinyl acetal resin.

  The ceramic green sheet of the present invention is formed into a sheet shape using the ceramic composition of the present invention.

  The ceramic sintered body of the present invention is manufactured by firing the ceramic green sheet containing ceramic powder having an average particle size of 0.1 to 10 μm and has a relative density of 95% or more.

  The ceramic composition of the present invention is obtained by adding an organic gelling agent composed of a polysaccharide derivative having an acid value of 0.1 mgKOH / g or more to a ceramic slurry containing a ceramic powder and a resin binder. The density can be adjusted well. Therefore, after preparing one type of slurry at first, it is only necessary to adjust the amount of the organic gelling agent to be added according to the target density of the green sheet. It can be adjusted well, and efficient production can be performed. In addition, since the organic gelling agent can be decomposed and eliminated in the degreasing and firing steps, it is possible to prevent problems such as firing failures caused by thermal decomposition residue. Furthermore, since the organic gelling agent composed of a polysaccharide derivative has an acid value of 0.1 mgKOH / g or more, hydroxyl groups and the like remain in an appropriate amount. The surface of the ceramic powder is coated by hydrogen bonding with a hydroxyl group present on the surface, thereby improving the dispersibility of the ceramic powder.

  Furthermore, the organic gelling agent used in the present invention is a polysaccharide derivative, preferably a polysaccharide fatty acid ester. In the polysaccharide fatty acid ester, the hydroxyl group remains moderately, so that the dispersibility of the ceramic powder is improved by the above-described effects, and the steric repulsion effect of the fatty acid substituted with the hydroxyl group of the polysaccharide improves the ceramic powder. It has the effect of preventing aggregation. It has also been found that the powder packing density of the green sheet can be adjusted appropriately by adding such polysaccharide derivatives.

  In the ceramic composition of the present invention, preferably, since the resin binder contains a polyvinyl acetal resin, the strength of the green sheet formed into a sheet shape using the ceramic composition of the present invention is strong and excellent in flexibility, Because of excellent adhesion, the processability of green sheet through-hole formation, printing, lamination, cutting, etc. is high, so it is possible to obtain ceramic sintered bodies with a wide range of applications and various characteristics and shapes. Become.

  The ceramic sintered body of the present invention is produced by firing a ceramic green sheet containing ceramic powder having an average particle size of 0.1 to 10 μm. The polysaccharide fatty acid ester used for adjusting the density of the green sheet is: Since it is excellent in the dispersibility in a slurry as above-mentioned, since it gelatinizes uniformly in a slurry, the obtained green sheet has few density dispersion | variations. In other words, since it becomes possible to effectively prevent the generation of large pores in the green sheet due to the local aggregation of the resin binder in the slurry, the variation in the size of the voids existing in the green sheet is small. . Therefore, the voids are uniformly crushed in the thermocompression bonding process when the green sheets are laminated, and the ceramic is sufficiently densified in the subsequent firing process. Therefore, the relative density of the ceramic sintered body of the present invention is 95% or more. The required properties such as strength and dimensional accuracy were found to be excellent. Furthermore, since the level | step difference produced with the electrode etc. is also absorbed, the ceramic sintered compact without defects, such as delamination, can be obtained.

  The ceramic composition of the present invention (commonly called ceramic slurry or ceramic paste), a green sheet using the ceramic composition, and a ceramic sintered body will be described in detail below.

  First, a green sheet for producing a ceramic sintered body is produced as follows. Add green binder powder, for example, ceramic powder or glass powder to ceramic powder as a sintering aid, if desired, and add additives such as resin binder, plasticizer, solvent, etc. to the mixture. In addition, a slurry is prepared. The polysaccharide derivative which is an organic gelling agent is added to the obtained slurry while adjusting the addition amount so as to obtain a desired green sheet powder packing density. Thereafter, a green sheet having a predetermined thickness is formed using the slurry by a forming method such as a doctor blade method, a rolling method, or a pressing method.

  Next, when forming a wiring conductor or the like, by punching the green sheet, a through-hole serving as a via hole connecting the upper and lower wiring conductor layers is formed, and the conductive paste is filled in the through-hole. . Hereinafter, each process will be described in detail.

  First, examples of the ceramic powder include metal or non-metal oxide such as iron and stainless steel, and non-oxide powder. These powders may be used in a single composition or in the form of a compound alone or in combination. Specifically, Li, K, Mg, B, Al, Si, Cu, Ca, Br, Ba, Zn, Cd, Ga, In, lanthanoid, actinoid, Ti, Zr, Hf, Bi, V, Nb, Ta , W, Mn, Fe, Co, Ni, and other oxides, carbides, nitrides, borides, sulfides, and the like.

More specifically, a composite oxide of SiO ₂ , Al ₂ O ₃ , ZrO ₂ , TiO ₂ and an alkaline earth metal oxide, ZnO, MgO, MgAl ₂ O ₄ , ZnAl ₂ O ₄ , MgSiO ₃ , Mg _{2 SiO 4, Zn 2 SiO 4} , Zn 2 TiO 4, SrTiO 3, CaTiO 3, MgTiO 3, BaTiO 3, CaMgSi 2 O 6, SrAl 2 Si 2 O 8, BaAl 2 Si 2 O 8, CaAl 2 Si 2 O ₈ , Mg ₂ Al ₄ Si ₅ O ₁₈ , Zn ₂ Al ₄ Si ₅ O ₁₈ , AlN, Si ₃ N ₄ , SiC, and a composite oxide containing at least one selected from Al ₂ O ₃ and SiO ₂ (For example, spinel, mullite, cordierite) and the like, and can be selected in accordance with the application.

Examples of the glass powder include SiO ₂ —B ₂ O ₃ , SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ , SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO (however, M Is Ca, Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ₁ O—M ₂ O system (where M ₁ and M ₂ are the same or different, and Ca, Sr , Mg, Ba or Zn), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ₁ O—M ₂ O (where M ₁ and M ₂ are the same as above), SiO ₂ —B ₂ O ₃ —M ₃ O system (where M ₃ is Li, Na or K), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ₃ O system (where M ₃ is the same as above), A glass containing at least one selected from the group consisting of Pb glass, Bi glass, alkali metal oxide, alkaline earth metal oxide, and rare earth oxide is preferable. These glasses become amorphous glass when fired, and when fired, lithium silicate, quartz, cristobalite, cordierite, mullite, anorthite, serdian, spinel, garnite, willemite, dolomite, petalite and their Crystallized glass that precipitates at least one type of substituted derivative crystal is used.

  The mixing ratio of the ceramic powder and the glass powder is a ratio used for an ordinary glass ceramic sintered body material, and is preferably 60:40 to 1:99 by weight.

Examples of the auxiliary component include B ₂ O ₃ , ZnO, MnO ₂ , alkali metal oxides, alkaline earth metal oxides, rare earth metal oxides, and the like, which can be selected according to use.

  In addition, as a material when the ceramic sintered body of the present invention is used as a piezoelectric element, crystals of perovskite type structures such as barium titanate and lead zirconate-lead titanate solid solutions are specifically mentioned. Include zirconate titanates such as lead zirconate titanate (PZT) and lead lanthanum zirconate titanate (PLZT), or lead titanate.

  These ceramic powders preferably have an average particle size of 0.1 to 10 μm, more preferably 0.3 to 5 μm. If it is smaller than 0.1 μm, the handleability is lowered such as difficulty in dispersion. On the other hand, if it is larger than 10 μm, it becomes difficult to make it dense during firing.

  The resin binder contained in the ceramic composition of the present invention preferably contains a polyvinyl acetal resin. This polyvinyl acetal resin is obtained by subjecting polyvinyl alcohol to an acetalization reaction with an aldehyde, and can be produced by a known method. That is, polyvinyl alcohol is dissolved in warm water or hot water, and the resulting polyvinyl alcohol aqueous solution is maintained at a predetermined temperature (for example, 0 to 95 ° C.), an aldehyde and an acid catalyst are added, and acetalization reaction is performed with stirring. Next, the reaction is completed by raising the reaction temperature and aging, and then, through various steps of neutralization, washing with water and drying, a method of obtaining a powdered polyvinyl acetal resin (for example, Patent Document 6).

  The polyvinyl alcohol used may be used alone, or two or more types having different average polymerization degrees may be used in combination.

  Although it does not specifically limit as an aldehyde used for manufacture of the said polyvinyl acetal resin, For example, formaldehyde, acetaldehyde, propionaldehyde, n-butyraldehyde, isobutyraldehyde, valeraldehyde, n-hexyl aldehyde, 2-ethyl Examples include butyraldehyde, benzaldehyde, cinnamaldehyde, and the like. These aldehydes may be used alone or in combination of two or more.

  The polyvinyl acetal resin thus obtained may be used alone, or two or more kinds may be used in combination. In particular, a polyvinyl butyral resin obtained by reacting polyvinyl alcohol and n-butyraldehyde is preferred. Used.

  Also, other resins can be used in combination as long as they are compatible with the polyvinyl acetal resin and do not impair the dispersion state of the slurry. Examples thereof include cellulose resins and alkyd resins. . In addition, even if the resin has a relatively low compatibility with the polyvinyl acetal resin, it can be added in a small amount. As such a resin, acrylic resins (acrylic acid, methacrylic acid or esters thereof) can be used. Homopolymers or copolymers, specifically acrylic ester copolymers, methacrylic ester copolymers, acrylic ester-methacrylic ester copolymers, etc.), polystyrene resins, polyvinyl acetate resins, Examples include homopolymers or copolymers such as polyvinyl chloride and polypropylene carbonate resins.

  The solvent of the ceramic composition of the present invention is not particularly limited as long as it is a solvent that dissolves the resin binder and disperses the ceramic, and examples of the non-aqueous solvent include toluene, benzene, xylene, and the like. Of aromatic hydrocarbons such as ethyl acetate, butyl acetate, isobutyl acetate, ketones such as methyl isobutyl ketone, methyl ethyl ketone, and acetone, aliphatic hydrocarbons such as hexane and heptane, diethyl ether, dipropyl ether, Examples thereof include one or more organic solvents selected from ethers such as tetrahydrofuran, alcohols such as methanol, ethanol, isopropyl alcohol, and butanol, and cell solves such as ethyl cellosolve.

  Moreover, you may add a plasticizer, a dispersing agent, etc. which are other additives to the ceramic composition of this invention as needed.

  Examples of the plasticizer include dimethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, diheptyl phthalate, di-n-octyl phthalate, diisononyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, ethyl phthalyl ethyl glycolate, butyl phthalate Phthalate esters such as rubutyl glycolate, aliphatic esters such as di-2-ethylhexyl adipate, dibutyl diglycol adipate, diethylene glycol, triethylene glycol, polyethylene glycol, diethylene glycol methyl ether, triethylene glycol methyl ether, diethylene glycol ethyl Ether, diethylene glycol-n-butyl ether, triethylene glycol-n-butyl ether, Ethylene glycols such as lenglycol phenyl ether, ethylene glycol-n-acetate, diethylene glycol monohexyl ether, diethylene glycol monovinyl ether, dipropylene glycol, tripropylene glycol, polypropylene glycol, dipropylene glycol methyl ether, tripropylene glycol methyl ether, di Propylene glycol monoethyl ether, dipropylene glycol-n-butyl ether, tripropylene glycol-n-butyl ether, propylene glycol phenyl ether, ethylene glycol benzyl ether, ethylene glycol isoamyl ether, and the like, and the like are selected. Use 1 type or 2 or more types. Of these, phthalic acid esters such as dibutyl phthalate (DBP) and di-2-ethylhexyl phthalate (DOP), and polyethylene glycol (PEG) are preferred.

  As the dispersant, for example, any of a nonionic surfactant, a cationic surfactant, an anionic surfactant, an amphoteric surfactant and a polymer type emulsifying dispersant can be used. Nonionic surfactants include polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, glycerin fatty acid partial ester, sorbitan fatty acid partial ester, pentaerythritol fatty acid partial ester, polyoxy Examples thereof include ethylene sorbitan acid fatty acid partial ester, polyoxyethylene alkyl ether carboxylate, fatty acid alkanolamide, polyoxyalkylene alkylamine, and alkyldialkylamine oxide. Examples of the cationic surfactant include alkylamine salts, dialkylamine salts, and quaternary ammonium salts. Anionic surfactants include ether carboxylates, dialkyl sulfosuccinates, alkane sulfonates, alkyl benzene sulfonates, alkyl naphthalene sulfonates, polyoxyethylene alkyl sulfophenyl ether salts, alkyl phosphate ester salts, Examples thereof include polyoxyethylene alkyl ether phosphates, sulfates of fatty acid alkyl esters, alkyl sulfates, polyoxyethylene alkyl ether sulfates, fatty acid monoglyceride sulfates, acylated amino acid salts, and the like. Examples of amphoteric surfactants include betaine-type amphoteric surfactants and amino acid-type amphoteric surfactants, and polymer-type emulsifying dispersants include polyvinyl alcohol, starch and its derivatives, carboxymethylcellulose, methylcellulose, hydroxyethylcellulose, etc. Cellulose derivatives, sodium polyacrylate, and the like, and one or more selected from these are used. Of these, polymer type emulsifying dispersants and nonionic surfactants are preferred.

  Next, an organic gelling agent comprising a polysaccharide derivative used in the ceramic composition of the present invention will be described. The organic gelling agent used in the present invention is a polysaccharide derivative, and more specifically, a polysaccharide fatty acid ester is preferable. The polysaccharide fatty acid ester can be produced by a known method. That is, the polysaccharide is dispersed in the reaction solvent, and a catalyst is added as necessary. It can be obtained by adding an acid halide or acid anhydride of a fatty acid and reacting it (for example, Patent Document 7).

  Specific examples of the polysaccharide constituting the polysaccharide derivative used in the ceramic composition of the present invention include starches, dextrin, dextran, xanthan gum, curdlan, carrageenan, welan gum, lambzan gum, succinoglucan, dextran, Carose, pullulan, amylose, agarose, celluloses, xanthan gum, guar gum, gellan gum, schizophyllan, pectin, agar, alginic acid, inulin, chitosan, chitin, etc., and their degradation products, processed products or chemical modifications Can do. In the structure of these polysaccharides, the sugar chain may be linear or branched. Of these, starches and dextrins that are hydrolysates thereof are preferred. The sugar polymerization degree of these polysaccharides is preferably about 3 to 150. When the degree of sugar polymerization is 2 or less, the gelation effect is small, and when the degree of sugar polymerization exceeds 150, the solubility may be lowered.

  Examples of the fatty acid substituted with a hydroxyl group of a polysaccharide include saturated fatty acids, branched fatty acids, and unsaturated fatty acids. For example, caprylic acid, capric acid, lauric acid, myristic acid, palmitic acid, stearic acid, isobutyric acid. , Isovaleric acid, 2-ethylbutyric acid, ethylmethylacetic acid, isoheptanoic acid, 2-ethylhexanoic acid, isononanoic acid, isodecanoic acid, isotridecanoic acid, isomyristic acid, isopalmitic acid, sorbic acid, linoleic acid, linolenic acid, etc. 1 type, or 2 or more types selected from these can be used. The degree of substitution of fatty acids with polysaccharides is 0.1-2.9 per unit sugar, and polysaccharide fatty acid esters with 1.0-2.5 in particular can be suitably used. Among these, dextrin palmitate, inulin stearate and the like can be suitably used.

  By appropriately adjusting the fatty acid substitution reaction to the hydroxyl group of the polysaccharide, when the hydroxyl group of the polysaccharide is left to some extent so as to have an acid value of 0.1 mgKOH / g or more, the residual hydroxyl group of the polysaccharide is It has the effect of improving the dispersibility of the ceramic by covering the ceramic surface by hydrogen bonding with the existing hydroxyl groups. In addition, there is an effect of preventing the aggregation of the ceramic by the steric repulsion effect between the fatty acids substituted with the hydroxyl group of the polysaccharide. Therefore, the effect similar to a dispersing agent can be expected by appropriately adjusting the degree of fatty acid substitution of the polysaccharide hydroxyl group. On the other hand, when most of the hydroxyl groups present in the polysaccharide are substituted with fatty acids so that the acid value is less than 0.1 mg KOH / g (when the degree of substitution of fatty acids with polysaccharides exceeds 3.0 per unit sugar) Such an effect of improving dispersibility tends to decrease.

  On the other hand, when a polysaccharide having a hydroxyl group substituted with an appropriate long-chain fatty acid is used, the long-chain fatty acid is crystallized at room temperature and the gelation effect due to hydrogen bonding between the remaining hydroxyl groups of the polysaccharide results in the slurry. The effect of aggregating the resin binder contained in is increased. Therefore, it was found that the powder packing density of the green sheet can be appropriately adjusted by adding a small amount of such a polysaccharide fatty acid ester to the slurry.

  Furthermore, since the polysaccharide fatty acid ester used in the present invention has both a polar group and a hydrophobic group, the polysaccharide fatty acid ester is also excellent in affinity with a resin binder such as polyvinyl acetal. Therefore, a local concentration difference between the resin binder and the polysaccharide fatty acid ester hardly occurs. In addition, since the polysaccharide fatty acid ester used in the present invention is excellent in dispersibility in the slurry as described above, it is gelled uniformly in the slurry, so that the resulting green sheet has a density variation. It turned out to be few. In other words, since it becomes possible to effectively prevent the generation of large pores in the green sheet due to the local aggregation of the resin binder in the slurry, the ceramic sintering of the present invention produced by firing it It was found that the body had little density variation and excellent characteristics such as dimensional accuracy. In addition, since the porcelain is sufficiently densified, it has been found that the ceramic sintered body of the present invention has a relative density of 95% or more and has excellent characteristics such as strength and dimensional accuracy.

  Moreover, since the level | step difference which arises when providing an electrode etc. on a green sheet can also be absorbed favorably at the time of lamination | stacking, the favorable ceramic sintered compact without a malfunction, such as a lamination, is obtained.

  Next, a method for adding the polysaccharide fatty acid ester to the slurry will be described. First, a slurry is prepared by an ordinary method, and a polysaccharide fatty acid ester solution dissolved in an appropriate solvent is added thereto. Solvent selection at this time is not limited as long as the polysaccharide fatty acid ester to be used is dissolved. For example, a solvent used in the above-described slurry can be suitably used. Thereafter, a green sheet having a predetermined thickness is formed using the slurry by a forming method such as a doctor blade method, a rolling method, or a pressing method.

  The amount of polysaccharide fatty acid ester added to the slurry is not particularly limited because the density adjusting effect varies depending on the type and combination of the ceramic raw material, resin binder, plasticizer and other additives used, and the amount. The amount of the resin binder contained in the slurry is preferably about 0.1 to 30% by weight, more preferably about 1 to 15% by weight, and still more preferably about 1 to 10% by weight. Even if a small amount of is added, the density adjusting effect is sufficient. If it is less than 0.1% by weight, the density adjusting effect may not be expected. On the other hand, if it exceeds 30% by weight, the excess polysaccharide fatty acid ester is easily separated in the drying process of the green sheet. When returning to room temperature, it may crystallize locally. In a ceramic sintered body fired using such a green sheet, relatively large pores may be locally formed, and the strength and required characteristics may be partially impaired.

  Furthermore, the density adjustment method of the green sheet by adding polysaccharide fatty acid ester to the slurry in the present invention will be described. By preparing a slurry in which several types of polysaccharide fatty acid esters are added in the manner described above in advance, preparing a green sheet and measuring the density, the relationship between the amount of polysaccharide fatty acid ester added and the density of the green sheet is obtained. Create the calibration curve shown. Based on the obtained calibration curve, the amount of polysaccharide fatty acid ester added may be determined so as to obtain a desired powder density of the green sheet. Since the method for adjusting the density of the green sheet by adding polysaccharide fatty acid esters in the present invention is excellent in reproducibility, a calibration curve need only be prepared once, and the subsequent production is performed based on the obtained calibration curve. Since the density of the green sheet can be accurately adjusted by a simple method of determining the addition amount of the saccharide fatty acid ester, efficient production can be performed.

  Next, the case where conductor parts such as metallized wiring and via conductors are formed will be described. Examples of the conductive paste include one or more of metal powders such as Au, Cu, Ag, Pd, W, Mo, Ni, Al, and Pt. In the case of two or more, mixing, alloy, etc. Either form may be sufficient. A mixture of these metal powders with a resin binder, a solvent, a plasticizer, a dispersant and the like can be suitably used.

  Examples of the resin binder for the conductive paste include acrylic, polyvinyl acetal, and cellulose homopolymers or copolymers, and contains at least one selected from these.

  Specific examples of acrylics include homopolymers or copolymers of acrylic acid, methacrylic acid or their esters, specifically acrylic ester copolymers, methacrylic ester copolymers, acrylic ester-methacrylic acid An ester copolymer may be used, and a hydroxyl group, a carboxylic acid group, an alkylene oxide group, a glycidyl group, an amino group, an amide group, or the like may be appropriately introduced into these copolymers. By introducing these, the effect of improving the dispersibility with ceramics and the effect of improving the viscosity and thixotropy can be expected. In addition, styrene, α-methylstyrene, acrylonitrile, ethylene, vinyl acetate, polyvinyl alcohol can be copolymerized with acrylic resin as long as the performance such as thermal decomposability and solubility in various solvents is not impaired. , N-vinylpyrrolidone or the like may be introduced as appropriate. Among these acrylic resins, one or two or more kinds can be appropriately selected and used as necessary.

  Examples of the solvent for the conductive paste include terpineol, dihydroterpineol, ethyl carbitol, butyl carbitol, carbitol acetate, butyl carbitol acetate, diisopropyl ketone, methyl cellosolve acetate, cellosolve acetate, butyl cellosolve, and butyl cellosolve. Acetate, cyclohexanone, cyclohexanol, isophorone, cypropylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, butyl carbitol methyl-3-hydroxyhexanoate, trimethylpentanediol monoisobutyrate, pine oil, mineral spirit, etc. The high boiling point solvent can be preferably used.

  The resin binder is preferably mixed at a ratio of 0.5 to 15.0 parts by weight with respect to 100 parts by weight of the metal powder, and the organic solvent is mixed at a ratio of 5 to 100 parts by weight with respect to 100 parts by weight of the solid component and the resin binder. In addition, you may add some inorganic components, such as glass powder and oxide powder, in this conductor paste. This conductor paste is printed on the green sheet in a predetermined pattern using a known printing method such as a screen printing method or a gravure printing method.

  The green sheet thus obtained is integrated by pressing and laminating with another green sheet by applying or transferring an appropriate adhesive comprising a resin binder, a solvent, and a plasticizer, or by a technique such as thermocompression bonding. To produce a green sheet laminate. A ceramic sintered body is obtained by firing the obtained green sheet laminate under predetermined conditions.

  Examples of the ceramic composition of the present invention, a green sheet using the ceramic composition, and a ceramic sintered body will be described below.

[1. Preparation of green sheet]
(Examples 1-9)
To 100 parts by weight of Al ₂ O ₃ having an average particle size of 1.5 μm, 10 parts by weight of glass ceramic mixed powder having an average particle size of 1.5 μm mainly composed of SiO ₂ , MgO, CaO, etc. 8 parts by weight of butyral as a resin binder, 2 parts by weight of dibutyl phthalate as a plasticizer, 35 parts by weight of toluene and 25 parts by weight of ethanol as a solvent were prepared as basic slurries, and the organic gel shown in Table 1 A 10% by weight toluene solution of the agent was added and mixed by a ball mill for 36 hours to prepare a slurry.

  The obtained slurry was degassed, then molded by the doctor blade method, dried, and then cut to produce a green sheet having a length of 50 mm × width 50 mm × thickness 0.3 mm. The density of the obtained green sheet was measured, respectively.

(Comparative Examples 1-3)
Green sheets were prepared in the same manner as in Examples 1 to 9 except that the amounts of toluene and ethanol added in the solvents in the examples were in the ratios shown in Table 1 and the organic gelling agent was not added.

[2. Preparation of ceramic sintered body]
A through hole (through hole) having a diameter of 200 μm was formed in each green sheet by punching, and a through hole filling conductor paste mainly composed of Cu was filled into the through hole formed in the green sheet by a screen printing method. . Next, a wiring pattern having a film thickness of 15 μm is printed and applied by a screen printing method using a conductor paste for wiring mainly composed of Cu, and subsequently dried at 80 ° C. for 1 hour using a hot air drying furnace to be metallized. Wiring was formed.

Subsequently, the obtained green sheets were combined by thermocompression bonding using five sheets, and a green sheet laminate having an internal wiring was produced. Next, this green sheet laminate is placed on an Al ₂ O ₃ setter and held at 850 ° C. for 3 hours in a nitrogen, hydrogen, water vapor mixed atmosphere firing furnace, and subsequently at 950 to 1000 ° C. Baked.

Table 1 shows the amount of the solvent used in Examples 1 to 9 and Comparative Examples 1 to 3, the type of organic gelling agent, and the amount added (in terms of solid content) in terms of% by weight based on the resin binder contained in the slurry. And the average value of the density of the obtained green sheet measured at a total of five points at the four corners and the central part and the evaluation of the variation in density with standard deviation.

  From Table 1, in Examples 1-9, the density of the green sheet was able to be adjusted accurately by adding a small amount of an organic gelling agent. It was also found that there was little density variation. On the other hand, when the addition ratio of toluene and ethanol was changed as in Comparative Examples 1 to 3, it was possible to adjust the density of the green sheets, but the standard deviation value indicating the variation was large.

Next, the evaluation result of the ceramic sintered body obtained in Table 2 is shown. First, the relative density of the ceramic sintered body was measured by Archimedes method after boiling in water for 2 hours. The measurement was performed for each sample with n (number) = 5, and the average value and the relative density variation were shown by standard deviation. Moreover, the continuity test of the wiring conductor part was performed, the presence or absence of the disconnection was confirmed, and the disconnection rate was obtained. On the other hand, the surface shape of the ceramic sintered body was measured with a high-speed three-dimensional shape measurement system (“EMS98AD-3D100XY” manufactured by Combs Co., Ltd.), and the maximum height difference was shown as the maximum value of warpage. Finally, the ceramic sintered body was cut and the presence or absence of large pores (pores) having a diameter (diameter) of 20 μm or more was observed with a scanning electron microscope.

  From Table 2, the results of the relative density were 96 to 99% in Examples 1 to 9, and the variation was small. This is because the organic gelling agent composed of the polysaccharide derivative used in the present invention is excellent in dispersibility in the slurry, so that it uniformly gels in the slurry. This is probably because the gaps were uniformly crushed in the thermocompression bonding process at the time of lamination, and the porcelain was sufficiently densified in the subsequent firing process. In addition, since the level difference caused by the wiring conductor and electrode was absorbed during the lamination process, a ceramic sintered body free from defects such as pores and delamination could be obtained.

  On the other hand, in Comparative Examples 1 to 3, there was a correlation between the relative density result and the green sheet density result. This is probably because a relatively large pore was locally formed and a large variation occurred in the powder packing density distribution of the green sheet, so that the porcelain was not sufficiently densified in the thermocompression bonding process and the firing process. For this reason, the density variation also increased.

  Regarding the disconnection rate, it did not occur in Examples 1 to 9, whereas in Comparative Examples 1 to 3, the disconnection rate increased in proportion to the density variation. This is presumably because a green sheet with a large density variation had a variation in shrinkage during the firing process, and a part of the wiring conductor made of the metallized layer was disconnected.

  Further, the maximum value of warpage of the ceramic sintered body was small in Examples 1 to 9, but relatively large in Comparative Examples 1 to 3. This is presumably because the ceramic sintered body was deformed as a result of variation in the amount of shrinkage in the firing process. Finally, the presence or absence of pores was also observed in Comparative Examples 2 and 3 where the relative density variation was relatively large. This is because when a large amount of poor solvent is used, delamination occurs due to the fact that relatively large pores were locally formed and that the level difference caused by the wiring conductor and electrode could not be absorbed well. Conceivable.

Claims (4)

A ceramic composition obtained by adding an organic gelling agent comprising a polysaccharide derivative having an acid value of 0.1 mgKOH / g or more to a ceramic slurry containing ceramic powder and a resin binder. The ceramic composition according to claim 1, wherein the resin binder includes a polyvinyl acetal resin. A ceramic green sheet formed into a sheet shape using the ceramic composition according to claim 1. A ceramic sintered body characterized by being produced by firing a ceramic green sheet according to claim 3 containing ceramic powder having an average particle size of 0.1 to 10 µm and having a relative density of 95% or more.