JP2012006808A - Ceramic green sheet and method of manufacturing the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a ceramic green sheet allowing suppressing a crack during punching process and deformation during pressing, and a method of manufacturing the ceramic green sheet.SOLUTION: In the ceramic green sheet 3, a binder 2 binding ceramic powder 1 includes: a first phase 2a having as a major component a vinyl-modified polyalkylene oxide chain made by binding a polyalkylene oxide chain and a polyvinyl alkylene oxide chain; and a second phase 2b having as a main component a polymethacrylic acid ester chain made by polymerizing methacrylic acid esters of 4C or less alcohol, wherein the first phase 2a and the second phase 2b form a sea-island structure and are binded with each other, in which the first phase 2a forms the sea and the second phase 2b forms the islands, by binding the vinyl group of the first phase 2a and the vinyl group of the second phase 2b. The flexibility of the binder 2 can be high in the first phase 2a and rigidity can be secured in the second phase 2b that has relatively high rigidity.

Description

  The present invention relates to a ceramic green sheet for producing a ceramic substrate used in an electronic component mounting substrate and the like, and a method for producing the same.

  Conventionally, as a wiring board used for mounting electronic components such as semiconductor elements and surface acoustic wave elements, circuit-like wiring and penetration are formed on an insulating substrate made of an aluminum oxide sintered body by a method such as metallization or plating. A wiring board on which a wiring conductor such as a conductor is attached is often used. Such an insulating substrate is generally manufactured by laminating a plurality of ceramic green sheets and then firing the laminate. The wiring conductor is coated or filled with a paste of a metal material such as tungsten or copper (conductor paste) on the surface of the ceramic green sheet or inside the through hole formed by punching the ceramic green sheet. It is formed by co-firing with a sheet.

  Conventionally, a general ceramic green sheet is obtained by bonding ceramic powders of raw materials such as aluminum oxide, silicon oxide, and calcium oxide with a binder made of a polymer such as acrylic polymer or polyvinyl butyral.

  In addition, such a ceramic green sheet is usually prepared by first adding ceramic powder and the polymer used as the binder to an organic solvent and kneading to prepare a slurry mainly composed of the ceramic powder, the binder, and the organic solvent. Thereafter, the slurry is formed into a sheet by a method such as a doctor blade method or a lip coater method, and unnecessary organic solvents are removed by heating. In this slurry, the ceramic powder and the binder are almost uniformly dispersed in the organic solvent, and therefore, with the removal of the unnecessary organic solvent, the ceramic powder is almost uniformly dispersed and bonded in the binder. .

JP 2001-172553 A JP 2007-165467 A JP 2009-120635 A

  In recent years, it has become necessary to increase the number of through-holes per unit area formed in a ceramic green sheet in response to the downsizing of electronic component mounting boards, the density of wiring conductors, and the like.

  On the other hand, in the conventional ceramic green sheet, when the number of through holes is increased, cracks are likely to occur in the ceramic green sheet due to the stress during mechanical punching to form the through holes. was there.

  Polyethylene, which is effective in reducing the stress by increasing the flexibility of the ceramic green sheet, is easy to deform such as rotation of the molecular chain because the ether chain is included in the molecular chain. It is conceivable to produce a binder having a polyalkylene oxide chain such as oxide as a main component.

  However, when a binder is produced with a polyalkylene oxide chain, the Young's modulus of the binder tends to be too low, and the ceramics are affected by the stress at the time of forming through holes, the pressure at the time of laminating a plurality of ceramic green sheets, etc. There is a possibility that the green sheet is deformed or the shape of the through hole is easily deformed.

  In particular, in recent years, there is a tendency to reduce the thickness of the ceramic green sheet or to reduce the opening of the through hole in accordance with the downsizing and thinning of the electronic component mounting substrate. Even if it is a thing, it is easy to produce a malfunction in the characteristic as a board | substrate for electronic component mounting, an external appearance, etc.

  The present invention has been completed in view of such conventional problems, and the purpose thereof is to effectively suppress the occurrence of cracks even when a stress associated with the formation of a through hole acts. Another object of the present invention is to provide a ceramic green sheet capable of ensuring mechanical strength and suppressing deformation, and a method for manufacturing the same.

  The ceramic green sheet of the present invention is a ceramic green sheet formed by bonding ceramic powder with a binder made of an organic resin, and the binder is a vinyl-modified polymer formed by bonding a polyalkylene oxide chain and a polyvinyl alkylene oxide chain. A first phase comprising an alkylene oxide chain as a main component and a second phase comprising as a main component a polymethacrylic acid ester chain obtained by polymerizing a methacrylic ester of an alcohol having 4 or less carbon atoms, the first phase And the second phase forms a sea-island structure in which the first phase is the sea and the second phase is the island by the combination of the vinyl group of the first phase and the vinyl group of the second phase. It is characterized by being connected to each other.

The method for producing a ceramic green sheet according to the present invention comprises preparing a slurry by kneading a binder made of an organic resin and ceramic powder together with an organic solvent, and then forming the slurry into a sheet shape and removing the organic solvent to remove the ceramic. In the method of manufacturing a ceramic green sheet in which powder is bonded with the binder, the binder is
A step of ring-opening polymerization of an alkylene oxide and a glycidyl vinyl compound to produce a first-phase binder mainly composed of a vinyl-modified polyalkylene oxide chain, which is a copolymer of a polyalkylene oxide chain and a polyvinyl alkylene oxide chain. When,
In water, the methacrylic acid ester monomer of alcohol having 4 or less carbon atoms is mixed or emulsified and suspended together with the first phase binder, and the methacrylic acid ester monomer is polymerized to form a polymethacrylic acid ester chain. The vinyl group of the second phase binder mainly comprising the polymethacrylic acid ester chain is subjected to radical chain transfer reaction with the vinyl group of the first phase binder, and the polyvinyl alkylene oxide chain of the first phase binder is The first phase binder is a sea, and the second phase binder is an island, and the first phase binder and the second phase binder are combined with each other in a sea-island structure. To do.

  According to the ceramic green sheet of the present invention, the first component mainly composed of a vinyl-modified oxide chain formed by bonding a polyalkylene oxide chain and a polyvinyl alkylene oxide chain, which are easy to deform because they contain an ether bond in the molecular chain. Since it has a phase, a binder can be made flexible. Therefore, even if a stress or the like is applied during the formation or lamination of the through hole, the stress can be effectively absorbed by the deformation of the binder, and the generation of cracks in the ceramic green sheet can be effectively suppressed.

In addition, the first phase is the sea, and the second phase is composed mainly of a polymethacrylic acid ester chain obtained by polymerizing a methacrylic ester of an alcohol having 4 or less carbon atoms, which has higher rigidity than the first phase. Therefore, the ceramic green sheet can be prevented from being deformed excessively by the second phase. That is, the second phase in this sea-island structure binder functions as a pseudo-cross-linking point, increases the Young's modulus of the binder, secures the mechanical strength of the ceramic green sheet, The deformation of the ceramic green sheet and the shape of the through hole can be suppressed by the pressure at the time of stacking the plurality of ceramic green sheets.

  Since the first phase is formed with the vinyl-modified polyalkylene oxide chain as the main component and the second phase is formed with the polymethacrylate ester as the main component, the second phase vinyl is added to the vinyl group of the first phase. Since the bonding between the first phase and the second phase is facilitated by bonding the groups, it is easy to produce the binder.

  Therefore, it is possible to provide a ceramic green sheet that can effectively suppress the generation of cracks, can ensure mechanical strength, suppress deformation, and can be easily manufactured.

  According to the method for producing a ceramic green sheet of the present invention, each step of preparing the above binder is provided, and the first phase binder mainly composed of a vinyl-modified polyalkylene oxide chain is mainly composed of a polymethacrylate chain. Since the second phase binder is bonded, it is easy to bond the vinyl group of the second phase binder to the vinyl group of the first phase binder by radical polymerization reaction.

  Further, since this reaction is carried out in water, the first phase mainly composed of hydrophilic vinyl-modified polyalkylene oxide chains surrounds the second phase binder mainly composed of hydrophobic polymethacrylic acid ester chains. It is also easy to produce a binder with a sea-island structure.

  In addition, the prepared binder is a polymer whose first phase binder is composed mainly of a soft vinyl-modified polyalkylene oxide chain, and the second phase binder is a relatively rigid alcoholic methacrylate having 4 or less carbon atoms. Since the polymethacrylic acid ester chain formed as a main component is a binder, it is effective in relieving the stress and can suppress excessive deformation.

  Accordingly, it is possible to provide a method for producing a ceramic green sheet that can effectively suppress the occurrence of cracks, can ensure mechanical strength, suppress deformation, and can be easily manufactured. Can do.

It is an expanded sectional view which expands and shows a part of section of the thickness direction of the ceramic green sheet of the present invention. It is an expanded sectional view which expands and shows the part of the binder in FIG. It is sectional drawing which shows 1 process at the time of producing a ceramic substrate using the ceramic green sheet of this invention. It is a structural formula which shows typically the chemical structure of the binder in the ceramic green sheet of this invention. It is reaction formula which shows typically an example of reaction which a 2nd phase couple | bonds with the 1st phase of a binder. It is a structural formula which shows typically the chemical structure of the binder in the ceramic green sheet of this invention. (A) And (b) is a reaction formula which shows typically the chemical reaction in the process of preparing a binder in the manufacturing method of the ceramic green sheet of this invention, respectively. It is sectional drawing which shows an example of the process in which the slurry in the manufacturing method of the ceramic green sheet of this invention is shape | molded in a sheet form.

  The ceramic green sheet of the present invention will be described with reference to the accompanying drawings. In the following description and the drawings to be referred to, n is the degree of polymerization of each polymer, and the degree of polymerization n in different polymers may be the same or different.

  FIG. 1 is an enlarged cross-sectional view showing a part of the cross section in the thickness direction of the ceramic green sheet of the present invention. FIG. 2 is an enlarged cross-sectional view showing the binder part in FIG. 1 further enlarged. . 1 and 2, 1 is a ceramic powder, and 2 is a binder including a first phase 2a and a second phase 2b. Ceramic powders 1 are bonded together via a binder 2 to form a ceramic green sheet 3.

  For example, as shown in FIG. 3, the ceramic green sheet 3 is subjected to processing such as formation of through holes 11 by mechanical punching and printing of the conductive paste 12, and a plurality of ceramic green sheets 3 as necessary. If the ceramic powders 1 are sintered while the binder 2 is decomposed and removed, the ceramic substrate (not shown) for mounting electronic components or the like is produced. FIG. 3 is a cross-sectional view showing a step in producing a ceramic substrate for mounting electronic components using the ceramic green sheet 3 of the present invention.

  In the ceramic green sheet 3 of the present invention, the binder 2 has a first phase 2a mainly composed of a modified polyvinyl alkylene oxide chain formed by bonding a polyalkylene oxide chain and a polyvinyl alkylene oxide chain, and has 4 or less carbon atoms. A second phase 2b mainly composed of a polymethacrylic acid ester chain obtained by polymerizing a methacrylic acid ester of alcohol, and the first phase 2a and the second phase 2b are composed of a vinyl group of the first phase 2a and a second phase 2b. Due to the bonding with the vinyl group of the phase 2b, the first phase 2a is the sea, and the second phase 2b is an island, and is bonded to each other.

  That is, in the binder 2 in the ceramic green sheet 3 of the present invention, a relatively high mechanical strength portion and a relatively flexible portion are combined in a sea-island microphase separation structure. In addition, the suppression of cracks and the securing of mechanical strength as the ceramic green sheet 3 are possible.

  According to such a ceramic green sheet 3, a flexible vinyl-modified polyalkylene oxide chain (the main component of the first phase 2a) and a relatively high-stiffness alcohol methacrylate having 4 or less carbon atoms are polymerized. By using the resulting polymethacrylic acid ester chain (the main component of the second phase 2b) (hereinafter simply referred to as polymethacrylic acid ester chain) as the binder 2, it is flexible and cracks are generated when punching through holes. It is possible to provide the ceramic green sheet 3 which is difficult to be deformed and has high dimensional stability.

That is, the binder 2 can be made flexible by the portion of the first phase 2a, which is the sea whose main component is a vinyl-modified polyalkylene oxide chain. The binder 2 has a sea-island structure in which the second phase 2b mainly composed of the polymethacrylic acid ester chain having high rigidity is dispersed as islands in the sea part mainly composed of vinyl-modified polyalkylene oxide. Therefore, it is possible to suppress the ceramic green sheet 3 from being deformed excessively by the second phase 2b. In this case, the second phase 2b in the binder 2 having the sea-island structure functions as a pseudo cross-linking point, the Young's modulus of the binder 2 is increased, and the mechanical strength of the ceramic green sheet 3 can be ensured. Therefore, it is possible to suppress deformation of the ceramic green sheet 3 or deformation of the shape of the through hole due to stress at the time of forming the through hole, pressure at the time of stacking the plurality of ceramic green sheets 3, or the like.

  Since the first phase 2a is formed with the vinyl-modified polyalkylene oxide chain as the main component and the second phase 2b is formed with the polymethacrylic acid ester as the main component, the second phase is added to the vinyl group of the first phase 2a. By bonding the vinyl group of the phase 2b, the first phase 2a and the second phase 2b are easily bonded. Therefore, the production of the binder 2 is easy and the workability is good.

  Therefore, it is possible to provide a ceramic green sheet 3 that can effectively suppress the occurrence of cracks, can ensure mechanical strength, suppress deformation, and can be easily manufactured. .

  The ratio of the first phase 2a and the second phase 2b in the binder 2 may be appropriately set according to the material, the particle size, the shape of the ceramic powder 1 to be used, and the use conditions such as the processing density of the through holes. For example, if the ceramic powder 1 has a small particle size and a large surface area, the binder 2 may contain about 40 to 80% by mass of the vinyl-modified polyalkylene oxide chain that is a flexible component.

The second phase 2b which is an island in the binder 2 is, for example, a spherical or elliptical sphere having a particle size of about 0.1 to 2 μm, and is distributed almost uniformly within the first phase 2a which is the sea.

  Further, the second phase 2b that is an island may be independent of each other, or may be a part of each other bonded together. In the case where the plurality of second phases 2b are partly bonded to each other, for example, since the plurality of second phases 2b are connected in a network shape, the rigidity of the ceramic green sheet 3 is improved. It is valid.

  The vinyl-modified polyalkylene oxide chain that is the main component of the first phase 2a is, for example, an ether bond (—O—) in the molecular chain including the polyalkylene oxide chain PAO and the polyvinyl alkylene oxide chain PVAO as shown in FIG. The ether bond portion is easily deformed including rotation. Therefore, the sea portion constituting the binder 2 is flexible. FIG. 4 is a structural formula schematically showing the chemical structure of the binder 2 of the ceramic green sheet 3 of the present invention. FIG. 4 shows an example in which a polyethylene oxide chain is used as the polyalkylene oxide chain PAO and a polyglycidyl acrylate chain is used as the polyvinyl alkylene oxide chain PVAO.

  Examples of the polyalkylene oxide chain PAO other than the polyethylene oxide chain include a polypropylene oxide chain and a polytetramethylene oxide chain.

  Examples of the polyvinyl alkylene oxide chain PVAO other than the polyglycidyl acrylate chain include a polymethacryloyl glycidyl chain, a polyallyl glycidyl ether chain, and a polyvinyl phenyl glycidyl ether chain.

  Polymethacrylic acid ester chain PME formed by polymerizing methacrylic acid ester of alcohol having 4 or less carbon atoms has a short carbon number of alcohol and 4 or less, so that the plasticizing effect of side chain ester is reduced, so that rigidity is low. high. Such polymethacrylic acid ester chain PME has a high glass transition point of about 50 ° C. or higher. Therefore, it is possible to ensure good flexibility at a temperature (about 10 to 35 ° C.) at the time of processing such as drilling or lamination of the general ceramic green sheet 3.

In the example shown in FIG. 4, methyl alcohol is used as the alcohol. That is, in this example, polymethyl methacrylate obtained by polymerizing methyl methacrylate is used as the polymethacrylate chain PME that is the main component of the second phase 2b.

  Examples of the alcohol having 4 or less carbon atoms include methyl alcohol, ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, isobutyl alcohol, s-butyl alcohol, and t-butyl alcohol.

  Further, the bond between the vinyl group of the first phase 2a and the vinyl group of the second phase 2b is, for example, as shown in FIG. 5, with a vinyl-modified polyalkylene oxide chain (vinyl group not yet formed) as the main component of the first phase 2a. Reaction product) is mixed with unpolymerized methacrylic acid ester to be the second phase 2b to polymerize the methacrylic acid ester, and the vinyl group at the end of the polymer chain is radicalized to the unreacted vinyl group of the first phase 2a. It can be carried out by a polymerization reaction.

  In addition, it is considered that the polyalkylene oxide chain PAO and the polyvinyl alkylene oxide chain PVAO which are repeating units of the vinyl-modified polyalkylene oxide are alternately bonded to a certain length as shown in FIG. 6, for example. . As described above, in the vinyl-modified polyalkylene oxide chain, the polyalkylene oxide chain PAO and the polyvinyl alkylene oxide chain PVAO are bonded without being biased, so that the first phase 2a which is the sea of the binder 2 having the sea-island structure is The second phase 2b can be bonded to the polymethacrylic acid ester in the binder 2 without being biased. Therefore, the second phase 2b, which is an island, can be dispersed in the binder 2 without being biased. FIG. 6 is a structural formula schematically showing the chemical structure of the binder 2 of the present invention. In FIG. 6, the same parts as those in FIGS. 2 and 4 are denoted by the same reference numerals.

In this case, the proportion of the polyvinyl alkylene oxide chain VPAO in the vinyl-modified polyalkylene oxide chain (that is, the proportion of the vinyl group contained) may be about 3 to 30%.
When the ratio of the polyvinyl alkylene oxide chain PVAO in the vinyl-modified polyalkylene oxide chain is the above-mentioned level, the strength of the bond of the first phase 2a with respect to the second phase 2b bonded by the bond between the vinyl groups is sufficient. Can be high. Moreover, it can suppress that the 2nd phase 2b which is an island of a sea island structure becomes small too much.

Further, the total weight average molecular weight of the vinyl-modified polyalkylene oxide chain is preferably 5000 to 100,000, more preferably 100,000 to 500,000, for example, when the ceramic powder 1 is aluminum oxide, borosilicate glass, or the like. If the weight average molecular weight of the vinyl-modified polyalkylene oxide chain is 50000 or more, the surface of the ceramic powder 1 can be sufficiently covered, and if it is 1000000 or less, the viscosity of the slurry is more effectively suppressed. Thus, it becomes easier to form the sheet better (for example, suppressing variation in thickness and variation in the filling degree of the ceramic powder 1). The weight average molecular weight of such a vinyl-modified polyalkylene oxide chain can be controlled by the amount of polymerization initiator or chain transfer agent used during polymerization.

  The first phase 2a may contain residual components (not shown) such as unreacted polyalkylene oxide chain PAO and polyvinyl alkylene oxide chain PVAO together with the main component vinyl-modified polyalkylene oxide chain. is there.

The weight average molecular weight of a polymethacrylic acid ester chain PME obtained by polymerizing a methacrylic ester of an alcohol having 4 or less carbon atoms, which is the main component of the second phase 2b, is preferably 5,000 to 100,000. If the weight average molecular weight is 5000 or more, the chain length of the polymethacrylic acid ester chain PME is sufficiently long, which is advantageous for securing the rigidity as the binder 2. If it is 100000 or less, the concentration of the terminal vinyl group Since it is easy to ensure a sufficiently high (ratio of vinyl groups in the polymethacrylic acid ester chain PME having a certain chain length), the bond of the second phase 2b to the first phase 2a can be further strengthened.

  The number average molecular weight of the polymethacrylic acid ester chain PME can be controlled by the ratio of the vinyl group (polyvinyl alkylene oxide chain PVAO) in the first phase 2a as described above, for example. That is, the number average molecular weight can be lowered by increasing the proportion of the polyvinyl alkylene oxide chain PVAC in the first phase 2a, and the number average molecular weight can be increased by decreasing the proportion.

  The ceramic powder 1 includes aluminum oxide, silicon oxide, magnesium oxide, calcium oxide, borosilicate glass, lithium glass, ferrite, forsterite, steatite, mullite, zirconia, barium titanate, aluminum nitride, silicon nitride. Etc. are used.

  In addition to the ceramic powder 1 and the binder 2, various additives may be added to the ceramic green sheet 3. Examples of such additives include coloring materials such as titanium oxide, chromium oxide, iron oxide, and molybdenum oxide, phosphate esters such as tributyl phosphate and triphenyl phosphate, DOP (dioctyl phthalate), DBP (dibutyl phthalate), and the like. Plasticizers such as phthalates, and dispersants such as polyacrylic acid, polymethacrylic acid, and polyvinylamine are suitably used.

  The ratio of the first phase 2a and the second phase 2b in the binder 2 may be appropriately set according to the material, the particle size, the shape of the ceramic powder 1 to be used, and the use conditions such as the processing density of the through holes. For example, if the ceramic powder 1 has a small particle size and a large surface area, the ratio of the first phase 2a mainly composed of a vinyl-modified polyalkylene oxide chain that is a flexible component is set to about 40 to 80% by volume. do it.

The second phase 2b which is an island in the binder 2 is, for example, a spherical or elliptical sphere having a particle size of about 0.1 to 2 μm, and is distributed almost uniformly within the first phase 2a which is the sea.

  Further, the second phase 2b that is an island may be independent of each other, or may be a part of each other bonded together. In the case where the plurality of second phases 2b are partially bonded to each other, for example, the plurality of second phases 2b have a structure connected in a network, so that the mechanical strength of the entire ceramic green sheet 3 is increased. It is more effective for improvement.

(Production method)
Next, the manufacturing method of the ceramic green sheet of this invention is demonstrated, referring drawings. FIGS. 7A and 7B are reaction formulas schematically showing chemical reactions in the step of preparing a binder in the method for producing a ceramic green sheet of the present invention.

  In the method for producing a ceramic green sheet of the present invention, a binder made of an organic resin and ceramic powder are kneaded together with an organic solvent to prepare a slurry, and then the slurry is formed into a sheet and the organic solvent in the slurry is removed. For example, in the manufacturing method in which the ceramic powder 1 is bonded with the binder 2 as shown in FIG. 1, the binder 2 is prepared in the following steps.

The slurry is formed by a doctor blade method, for example, as shown in FIG. In FIG. 8, 21 is a hopper that holds a certain amount of slurry (no symbol), 22 is a roller, and 23 is a strip of paper. By feeding the belt-like paper 23 at a constant speed by the roller 22 and applying the slurry on the belt-like paper 23 with a constant thickness from the hopper 21, the slurry is formed into a sheet. The coating thickness of the slurry is adjusted by moving (sliding) the doctor blade 24 arranged at the slurry outlet in the hopper 21 up and down. In addition, FIG. 8 is sectional drawing which shows an example of the process of shape | molding a slurry in a sheet form in the manufacturing method of the ceramic green sheet of this invention.

  First, as shown in FIG. 7 (a), ring-opening polymerization of an alkylene oxide and a glycidyl vinyl compound, and a vinyl-modified polyalkylene oxide chain that is a copolymer of a polyalkylene oxide chain PAO and a polyvinyl alkylene oxide chain PVAO. A binder for the first phase containing as a main component is prepared.

  In the example shown in FIG. 7A, ethylene oxide is used as the alkylene oxide, and glycidyl methacrylate is used as the glycidyl vinyl compound. Examples of alkylene oxides other than ethylene oxide include propylene oxide and tetramethylene oxide. Examples of glycidyl vinyl compounds other than glycidyl acrylate include methacryloyl glycidyl, allyl glycidyl ether, and vinylphenyl glycidyl ether.

  In this case, the mixing ratio of alkylene oxide and vinyl alkylene oxide is such that the ratio of the polyvinyl alkylene oxide chain PVAO in the vinyl-modified polyalkylene oxide chain after polymerization is the same as the ratio in the ceramic green sheet 3 of the present invention. Set as follows.

  Next, in water, as shown in FIG. 7B, together with the first phase binder, a methacrylic acid ester monomer having 4 or less carbon atoms is emulsified or suspended and mixed. Polymerization is performed to form a polymethacrylic acid ester chain, and the vinyl group of the second phase binder mainly composed of the polymethacrylic acid ester chain is subjected to a radical polymerization reaction with the vinyl group of the first phase binder.

  In the example shown in FIG. 7B, methyl methacrylate is used as the methacrylate ester. Examples of the alcohol having 4 or less carbon atoms include ethyl alcohol, propyl alcohol, butyl alcohol, isopropyl alcohol, isobutyl alcohol, s-butyl alcohol and t-butyl alcohol in addition to methyl alcohol.

  By this radical polymerization reaction between the vinyl group of the second phase binder and the vinyl group of the first phase binder, the first phase binder is the sea and the second phase binder is the island, and the sea island structure is the first. The phase binder and the second phase binder can be coupled together.

  In the binder formed by coupling the first phase binder and the second phase binder, the first phase binder and the second phase binder, which are coupled to each other, respectively, for example, the book as shown in FIG. It becomes the first phase 2a and the second phase 2b in the binder 2 of the ceramic green sheet 3 of the invention.

  The polymethacrylic acid ester chain PME generally has a linear structure, and the molecular chain itself is linear, but is suspended or emulsified in water as described above and bonded to the first phase binder. The hydrophobic second phase binder bonded to the hydrophilic first phase binder becomes an island shape and is dispersed in the first phase binder (so-called emulsion). For this reason, the second phase binder is dispersed in the first phase binder as islands in a granular shape such as a spherical shape or an elliptical spherical shape.

  According to the method for producing a ceramic green sheet, the polymethacrylic acid ester is added to the first phase binder comprising the vinyl modified polyalkylene oxide chain containing the polyvinyl alkylene oxide chain PVAO as a main component, including the steps described above for preparing the binder 2. Since the second phase binder mainly composed of chain PME is bonded, it is easy to bond the vinyl group of the second phase binder to the vinyl group of the first phase binder by a radical polymerization reaction. .

  Further, since this reaction is performed in water, the first phase mainly composed of hydrophilic vinyl-modified polyalkylene oxide chain surrounds the second phase binder mainly composed of hydrophobic polymethacrylic acid ester chain PME. It is also easy to produce the binder 2 with a sea-island structure.

  Further, the produced binder 2 has a first-phase binder (first phase 2a) mainly composed of a flexible vinyl-modified polyalkylene oxide chain, and a second-phase binder (second phase 2b) is relatively rigid. The main component is polymethacrylic acid ester chain PME formed by polymerizing methacrylic acid ester of alcohol having a high carbon number of 4 or less, so that it is effective in relieving stress and suppressing excessive deformation. It becomes the binder 2 which is possible.

  Accordingly, it is possible to provide a method for producing a ceramic green sheet that can effectively suppress the occurrence of cracks, can ensure mechanical strength, suppress deformation, and can be easily manufactured. Can do.

  One embodiment of the ceramic green sheet of the present invention will be described.

The ceramic powder used was a powder of an aluminum oxide sintered body having an average particle diameter of 1.7 μm as a main component, to which about 3% by mass of silicon oxide and calcium oxide borosilicate glass powder was added. The ceramic green sheet contains 90% by mass of the ceramic powder and 10% by mass of the binder, and the thickness is adjusted to about 100 μm and is produced by a doctor blade method.

In the examples described below, the chemical structure of the binder is analyzed by ( ¹ H-NMR (proton-nuclear magnetic resonance), and the second phase, which is an island in the first phase, which is the sea that constitutes the binder. The shape was confirmed by thinly cutting the ceramic green sheet to obtain a sample, coloring this with an osmium salt, and then observing it with a TEM (transmission electron microscope).

Example 1
In Example 1, the first phase constituting the binder is composed of a polyethylene oxide chain and a polyacryloylethylene oxide chain prepared by copolymerization of ethylene oxide and glycidyl methacrylate as a vinyl-modified polyalkylene oxide chain as a main component. A copolymer was used. The first phase contained 95% by mass of the main component vinyl (acryloyl) -modified polyethylene oxide chain. The weight average molecular weight of the vinyl-modified polyalkylene oxide chain was about 135000.

  Moreover, the polymethyl methacrylate chain | strand was used for the 2nd phase as the polymethacrylic acid ester chain | strand which is a main component. In the second phase, methyl methacrylate was emulsified and mixed with the first phase binder in water and radically polymerized to bind to the first phase. The polymethacrylic acid ester chain had a weight average molecular weight of about 980,000.

Ratio of second phase in binder (area ratio in sample cross section) (%), and second
The size of the phase (maximum passing dimension on the observation surface of the sample) (μm) was adjusted to the value shown in Table 1, and for each, the rigidity of the ceramic green sheet produced using the binder and the cracking at the time of through-hole formation The presence or absence was confirmed. In Table 1, those using the binder of Example 1 are entered as “1” in the remarks column.

(Example 2)
In Example 2, polymethacrylic acid isobutyl chain (alcohol having 4 carbon atoms) is used as the polymethacrylic acid ester chain which is the main component of the second phase, and the other conditions are the same as in Example 1. A binder was produced. The ratio and size of the second phase in the binder of Example 2 were also set in the same manner as in Example 1. A ceramic green sheet was prepared using this binder, and the rigidity and the presence or absence of cracks during the formation of the through hole were confirmed in the same manner as in Example 1. In Table 1, for those using the binder of Example 2, Actual 2 is entered in the remarks column.

(Comparative example)
In addition, as a comparative example, a polypentyl methacrylate chain produced using pentyl alcohol (alcohol having 5 carbon atoms) which is an alcohol having 5 carbon atoms and 2-ethylhexyl alcohol which is an alcohol having 8 carbon atoms are used. A ceramic green sheet was prepared with a binder having the polyethyl methacrylate 2-ethylhexyl chain as the main component of the second phase, and the rigidity and presence of cracks were confirmed in the same manner as in Examples 1 and 2 above. .

(Measurement and results)
The mechanical strength of the ceramic green sheet was measured with a tensile meter. In addition, the through hole is formed by mechanical punching using a metal pin, and a rectangular shape having an opening diameter of 100 □ μm is 100 × 100 so that the distance between adjacent ones is 100 μm. Arranged vertically and horizontally. And the presence or absence of the crack was performed by the microscopic inspection by a coloring test.

  The test results are shown in Table 1. In Table 1, the columns * M, * V, * P, and * H indicate the ceramic green sheets of the comparative examples, respectively. * M uses only polymethyl methacrylate as a binder. * P is a polypentyl methacrylate chain as the main component of the second phase, and * H is a polymethacrylic acid as the main component of the second phase. A 2-ethylhexyl chain is used. In addition, the ratio of the 2nd phase in * P and * H which shows the result of a comparative example was 25%, and the magnitude | size of the 2nd phase was 0.9 or 1.0 micrometer.

  As can be seen from the results shown in Table 1, in any of the ceramic green sheets of the present invention, the mechanical strength was high and the occurrence of cracks was effectively suppressed. On the other hand, the ceramic green sheet of the comparative example was produced using only polymethyl methacrylate as the binder. * M has a relatively high mechanical strength, but many cracks are generated on the tape surface, and vinyl-modified polyethylene is used as the binder. In the case of * V produced using only an oxide chain, although the generation of cracks was suppressed, the mechanical strength was low. Moreover, in the example (* P and * H) in which the second phase of the binder was produced using alcohols having 5 and 8 carbon atoms, the mechanical strength was low.

Moreover, when the result (Example 2) of the sample No. 13 whose carbon number of the alcohol used for formation of the polymethacrylic acid ester chain is 4 is compared with the result of the comparative example * P having 5 carbon number, Example The mechanical strength (about 3.4 MPa) of the ceramic green sheet is sufficiently high, whereas the mechanical strength (about 0.9 MPa) of the ceramic green sheet of the comparative example is low. As a result, the second
The effect which made the polymethacrylic acid ester chain | strand which is a main component of a phase polymerize the methacrylic acid ester of C4 or less alcohol has been confirmed.

  As described above, in the ceramic green sheet of the present invention, it is confirmed that the occurrence of cracks can be effectively suppressed, and that the ceramic green sheet can have sufficient rigidity to suppress deformation due to pressurization or the like. We were able to.

DESCRIPTION OF SYMBOLS 1 ... Ceramic powder 2 ... Binder 2a ... 1st phase 2b ... 2nd phase 3 ... Ceramic green sheet PAO ... Polyalkylene oxide chain PVAO Polyvinyl alkylene oxide chain PME・ Polymethacrylate chain

Claims (2)

A ceramic green sheet formed by bonding ceramic powder with a binder made of an organic resin, wherein the binder is mainly composed of a vinyl-modified polyalkylene oxide chain formed by bonding a polyalkylene oxide chain and a polyvinyl alkylene oxide chain. Including a first phase and a second phase mainly composed of a polymethacrylic acid ester chain obtained by polymerizing a methacrylic acid ester of an alcohol having 4 or less carbon atoms, wherein the first phase and the second phase are The first phase is a sea and the second phase is an island by bonding between the vinyl group of the first phase and the vinyl group of the second phase, and is bonded to each other. Ceramic green sheet. A ceramic green sheet in which a binder made of an organic resin and a ceramic powder are kneaded with an organic solvent to prepare a slurry, and then the slurry is formed into a sheet and the organic solvent is removed and the ceramic powder is bonded with the binder. In the manufacturing method, the binder is
A step of ring-opening polymerization of an alkylene oxide and a glycidyl vinyl compound to produce a first-phase binder mainly composed of a vinyl-modified polyalkylene oxide chain, which is a copolymer of a polyalkylene oxide chain and a polyvinyl alkylene oxide chain. When,
In water, the methacrylic acid ester monomer of alcohol having 4 or less carbon atoms is mixed or emulsified and suspended together with the first phase binder, and the methacrylic acid ester monomer is polymerized to form a polymethacrylic acid ester chain. The vinyl group of the second phase binder mainly composed of the polymethacrylic acid ester chain is subjected to radical polymerization reaction with the vinyl group of the first phase binder, and the first phase binder is the sea, and the second A method for producing a ceramic green sheet, comprising preparing a first phase binder and a second phase binder in a sea-island structure in which a phase binder is an island.

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