JP2003313080A - Ceramic multilayer green sheet and method for forming pattern thereon - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a ceramic green sheet on which a favorable pattern can be formed by a photolithographic method by using a photosensitive paste without producing residue during developing or delamination during calcining, and to provide a method for forming a pattern. <P>SOLUTION: The ceramic multilayer green sheet consists of a layered body of a plurality of ceramic green sheets in which the binder included in at least the uppermost layer has a solvent resistance higher than that of the binder included in other layers. Preferably, the binder included in the uppermost layer consists of a copolymer of (meth)acrylic ester or its derivative and the thickness of the uppermost layer is 3 to 50% of the thickness of the whole sheet. Various kinds of patterns such as a conductor pattern and a resistor pattern can be efficiently formed by applying a photosensitive paste on the ceramic multilayer green sheet, drying, then selectively exposing according to a specified pattern and developing. <P>COPYRIGHT: (C)2004,JPO

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a ceramic laminated green sheet and a method for forming a pattern such as a conductor pattern and a resistor pattern on it. In the present specification, the ceramic green sheet is preferably used for high-density mounting in which a green sheet made of ceramic for manufacturing a passive element, a semiconductor element, etc. are mounted and they are mutually wired. A fired ceramic substrate, particularly a green sheet made of a ceramic preferably used for a multilayer ceramic substrate is referred to, and a ceramic laminated green sheet is a ceramic green sheet having a plurality of layers. The ceramic laminated green sheet of the present invention can be particularly advantageously used for forming a fine circuit pattern of the surface layer and inner layer electrodes of the ceramic multilayer substrate.

[0002]

2. Description of the Related Art Multilayer ceramic substrates are mainly manufactured by a green sheet laminating method. The green sheet laminating method is a method of printing a conductor layer, laminating a large number of green sheets that have been subjected to via hole processing, thermocompressing them, and then firing them simultaneously to form a multilayer substrate. Conventionally, as a method for forming a conductor pattern on a ceramic green sheet substrate, a screen printing method using a conductive paste has been adopted. However, with this method, it is difficult to form a fine pattern of L (line width) / S (width interval) = 60 μm / 60 μm or less.

On the other hand, a method of forming a fine conductor pattern by using a photolithography method using a photosensitive conductive paste has been conventionally known (for example, Japanese Patent Laid-Open No. 63-265979). Japanese Patent Laid-Open No. 5-6
7405, JP-A-11-249301, and JP-A-5-204151). However, this method can be advantageously applied to the case where a ceramic substrate after firing is used, but it is preferable to form a conductor pattern using a photosensitive conductive paste on a conventional green sheet that has not been fired, and then simultaneously fire it. In the case of, since the solvent resistance and the developer resistance of the green sheet are inferior, the polymer binder in the green sheet swells or is damaged by the organic solvent or the monomer contained in the photosensitive conductive paste, Further, it is very difficult to cleanly remove the unexposed portion during development, and there is a problem that a residue is generated.

As a measure against such a problem, Japanese Unexamined Patent Publication (Kokai) No. 8-34096 proposes to form a resin layer made of a cured film of a photosensitive resin composition on a ceramic green sheet. However, when such a resin layer is formed on a ceramic green sheet, delamination (a phenomenon in which peeling or cracks occur between the ceramic sheet and the conductor pattern layer after firing) occurs during firing. was there. Also, 40
It may be difficult to completely burn (debinding) at a low temperature of 0 to 450 ° C.

[0005]

SUMMARY OF THE INVENTION The present invention has been made to solve the problems of the prior art as described above.
Its main purpose is to form a good pattern by a photolithography method without generating a residue when a photosensitive paste is applied on a ceramic green sheet, dried and developed, or delamination during firing. It is intended to provide a method capable of efficiently forming various patterns such as a conductor pattern and a resistor pattern on a green sheet and a ceramic green sheet.

[0006]

In order to achieve the above object, according to the present invention, it comprises a laminate of a plurality of layers of ceramic green sheets, and the binder contained in at least the uppermost layer is contained in other layers. Provided is a ceramic laminated green sheet, which is characterized by being more excellent in solvent resistance than the binder. In a preferred embodiment, the binder contained in the top layer comprises a (meth) acrylic acid ester copolymer and its derivatives. The thickness of the uppermost layer is 3 to 50% of the total thickness of the sheet.
Is preferred. Further, according to the present invention, the above-mentioned ceramic laminated green sheet is coated with a photosensitive paste, dried, and then selectively exposed to a predetermined pattern, and then developed, and then developed. A method for forming a pattern on a green sheet is provided.

[0007]

BEST MODE FOR CARRYING OUT THE INVENTION As described above, in order to deal with the problem when a pattern is formed on a green sheet which has not been fired using a photosensitive paste, that is, a problem that a residue is generated during development, When a resin layer made of a cured film of a photosensitive resin composition is formed on a ceramic green sheet as described in Kaihei 8-34096,
There is a problem that delamination occurs during firing, and it becomes difficult to completely burn (debinding) at a low temperature of 400 to 450 ° C, and cracks and the like may occur during subsequent cofiring. .

As a result of earnest studies on such problems, the present inventors have found that the polymer binder in the green sheet is swollen or damaged by the organic solvent or monomer contained in the photosensitive conductive paste, or As a result, the surface becomes rough as if it were roughened. As a result, conductive powder is trapped (retained) in the recesses of the green sheet with a rough surface, and it is extremely difficult to cleanly remove the unexposed areas during development. In order to solve this, it is difficult to obtain a residue, and problems such as delamination are caused by the presence of a heterogeneous layer having poor adhesive strength between the green sheet and the pattern layer. In the sense that it contains ceramic powder, it has a structure consisting of a laminate of multiple layers of ceramic green sheets of the same type, and is contained in at least the uppermost layer. Found that there needs to be excellent in solvent resistance than the binder the binder contained in the other layers, in which the present invention has been completed.

That is, the ceramic laminated green sheet of the present invention comprises a laminated body of a plurality of layers of ceramic green sheets, and the binder contained in at least the uppermost layer is more excellent in solvent resistance than the binder contained in other layers. It is characterized in that it is composed of a copolymer of (meth) acrylic acid ester or a derivative thereof which is more excellent in solvent resistance than, for example, polyvinyl butyral which has been conventionally used as a binder. Since the solvent resistance is required only in the uppermost layer that comes into contact with the photosensitive paste, as the binder contained in the other layers, polyvinyl butyral or the like, which is excellent in debinding property as in the conventional case, is used. Can be used.

As described above, the ceramic laminated green sheet of the present invention is provided with a layer having a high solvent resistance and a high developer resistance in the surface layer portion, so that the solvent resistance and the developer resistance are inferior as in the conventional case. As a result, it is possible to prevent the polymer binder in the green sheet from being swollen or attacked by the organic solvent or monomer contained in the photosensitive paste, and also the uppermost layer. Since the other layers thereunder are also of the same type in the sense that they contain ceramic powder, the occurrence of delamination during firing can be avoided.
As a result, even if a pattern is formed on the ceramic laminated green sheet by a photolithography method using a photosensitive paste, the uncured portion of the unexposed portion can be completely removed, and a residue during development or baking A fine pattern can be formed without the occurrence of delamination or the like.

The ceramic laminated green sheet of the present invention and the method for producing the same will be described below. Ceramic green sheets are usually ceramic powder, organic binder, diethyl phthalate, butylbenzyl phthalate,
Ester plasticizers such as dibutyl phthalate, dioctyl phthalate and butyl phthalyl butyl glycolate, ketones such as methyl ethyl ketone, methyl isobutyl ketone and acetone, hydrocarbons such as toluene, xylene and normal hexane, methanol, ethanol and isopropyl alcohol. Dispersion of alcohols such as butanol, solvents such as esters such as ethyl acetate and butyl acetate, and nonionic surfactants such as fatty acid esters and anionic surfactants such as carboxylates and sulfonates as necessary. It is carried out by appropriately blending agents and the like, mixing them to form a slurry, and then forming the slurry on a carrier film by a known method such as a doctor blade method. In the production of the ceramic laminated green sheet in the present invention, Is before Fabricating a multilayer structure as described.

One method of making a ceramic green sheet into a multi-layer structure is to form a ceramic slurry on a carrier film by a doctor blade method, dry it into a green sheet, and then again form a doctor blade method or a printing method. Is a method of repeating film formation. Similar film formation is possible even if the doctor blade method is replaced with a calendar roll method or a curtain coating method. As another method, each ceramic slurry is formed into a single layer on a carrier film, and the upper layer ceramic green sheets thus individually produced are laminated on the lower layer ceramic green sheet, and rolled or pressed. There is a method of bonding by thermocompression. In either method, it is necessary that the ceramic slurry or ceramic green sheet applied to the uppermost layer contains a binder having a higher solvent resistance than the binder contained in the ceramic green sheets of the other layers. is there.

The ceramic powder contained in the ceramic laminated green sheet includes ceramic powder alone, glass-ceramic composite system, crystallized glass system, non-glass system, etc., but is not limited to a specific firing temperature. Any known ceramic raw material for low temperature firing or high temperature firing can be used. Usually 850 for low temperature
Ceramic raw materials that can be sintered at up to 1000 ° C. and at high temperatures of 1400 to 1650 ° C.

The ceramic powder that can be used alone is not particularly limited and various ones can be exemplified. For example, partially stabilized zirconia, stabilized zirconia, alumina, titania, mullite, spinel, beryllia, magnesia, Examples thereof include zircon powder, cordierite powder, barium titanate powder, lead titanate powder, lead zirconate titanate powder, silicon nitride, and materials containing aluminum nitride as a main component or a mixture thereof. Further, a material to which silica, clay, a transition metal oxide or the like is added as a sintering aid may be used. As a stabilizer for the partially stabilized zirconia, yttria, magnesia, ceria, calcia, ytterbia, and other rare earth metal oxides can be used.

As the binder contained in the ceramic laminated green sheet of the present invention, a conventionally known resin can be used, but it has a combustion property of 400 to 45.
Complete combustion (debinding) at a low temperature of 0 ° C is required. As the binder used in the lower layer, binders such as polyvinyl butyral (PVB), cellulose and derivatives thereof which have been conventionally used as binders for ceramic green sheets can be used. On the other hand, as the binder used in the uppermost layer, as described above, it is necessary to use those having excellent solvent resistance and developer resistance than these binders,
Examples thereof include acrylic binders such as copolymers of (meth) acrylic acid esters such as methyl (meth) acrylate and isobutyl (meth) acrylate and derivatives thereof. In this specification, (meth) acrylate is a general term for acrylate and methacrylate, and the same applies to other similar expressions.

Further, in order to suppress the generation of residues during development, it is effective to smooth the uppermost layer. In order to improve the smoothness of the uppermost layer, the grain size of the ceramic powder contained in it is made finer than the grain size of the ceramic powder contained in the other layer, or the content ratio of the binder is increased. Good. In addition, the smoothness of the uppermost layer can be improved by adjusting the particle size distribution and using the ceramic powder having a high bulk density. As a method of reducing the particle size of the ceramic powder, a method of prolonging the crushing time of the slurry with a ball mill or an attritor mill can be used. For example, when the crushing time of an ordinary ball mill is one day, a slurry in which the particle size of ceramic powder is made fine can be obtained by carrying out the crushing for four days. The ratio of ceramic powder to binder is 90:
10 to 70:30 is suitable, but in order to improve the smoothness of the uppermost layer, the amount of the binder in the slurry used in the uppermost layer is made larger than that in the other layers. For example, the ratio of the ceramic powder to the binder in the uppermost layer is 80:20 to 70:30, and the other layers below it are 90:10 to 8 similar to the conventional green sheet.
By setting the ratio to 0:20, the smoothness is improved, and the generation of the residue of the inorganic powder such as silver powder on the green sheet after development can be suppressed.

The thickness of the uppermost layer is 3 to 50%, preferably 3 to 3% of the total thickness of the ceramic laminated green sheet.
0% When a binder having a poor debinding property is used as the binder for the uppermost layer, if the thickness of the uppermost layer exceeds 30% of the total thickness, the green sheet is baked to remove the resin composition. It is not preferable because it may take time or carbon may remain after firing in an inert atmosphere, which may cause insulation failure or delamination. Normally, the thickness of the ceramic green sheet is about several tens of μm to several hundreds of μm depending on the application, so the optimum film thickness of the uppermost layer is not constant, but considering the ease of film formation and debinding property, For example, when the total film thickness is 400 μm, about 20 μm is appropriate, and for example, the total film thickness is 4 μm.
In the case of 0 μm, about 5 μm is appropriate.

The thickness ratio of the uppermost layer to the lower layer must be within the range of 3:97 to 50:50, preferably within the range of 5:95 to 30:70. Is. Considering the removability (debinding property) of the resin composition, the thinner the uppermost layer, the better. However, when the unevenness of the ceramic green sheet of the lower layer has a depth of several μm or more, if the film thickness of the uppermost layer is less than 5 μm, the uppermost layer using fine ceramic powder is less than 5 μm. Even if it is used, the effect of reducing unevenness is weakened, so that the uppermost layer is preferably 5 μm or more.

Next, a method for forming a pattern on the ceramic multi-layer green sheet manufactured as described above by using a photosensitive paste by a photolithography method will be described. As the photosensitive paste, a photosensitive conductive paste, a photosensitive resistor paste, a photosensitive dielectric paste, a photosensitive insulating paste, etc. are used, and each of them contains a resin binder, a photopolymerizable monomer, a photopolymerization initiator, etc. The conductive resin composition contains a conductive powder, a resistor powder, and a dielectric powder. Known and commonly used components can be used for the components of these photosensitive pastes.

First, a photosensitive paste such as a photosensitive conductive paste or a photosensitive resistor paste is applied on the ceramic laminated green sheet prepared as described above by a dip coating method, a screen printing method, a squeegee, It is applied by a known method using a dispenser or a roller, and dried. After that, the coating film is selectively exposed to a predetermined pattern through a photomask, photocured, and developed to form a high-definition pattern on the ceramic laminated green sheet.

Here, as a light source used for exposure,
Low-pressure mercury lamps, high-pressure mercury lamps, ultra-high-pressure mercury lamps, halogen lamps, germicidal lamps, laser lights, black lamps, electrodeless lamps, etc. are used. Of these, an ultra-high pressure mercury lamp is preferable. The exposure conditions vary depending on the film thickness of the applied photosensitive paste, but the range of 50 to 5000 mJ / cm ² is preferable. When the exposure amount is in this range, photocuring is sufficiently achieved, so that solvent resistance and developer resistance are improved.

The development after exposure can be carried out by a dipping method or a spraying method as in the conventional case. When the resin binder is a photosensitive resin having a carboxyl group, it can be developed with an alkaline aqueous solution. As the alkaline aqueous solution, a metallic alkaline aqueous solution such as an aqueous solution of sodium hydroxide or calcium hydroxide can be used, but it is preferable to use the organic alkaline aqueous solution because the alkaline component can be easily removed during firing. Specific examples of the organic alkali include tetramethylammonium hydroxide, trimethylbenzylammonium hydroxide, monoethanolamine, diethanolamine and the like. The concentration of the alkaline aqueous solution is usually 0.2 to 1%. An organic solvent can be used as the developing solution. Further, water may be added to the organic solvent within a range in which its dissolving power is not lost. In addition, it is preferable to wash with water or neutralize the acid after the development to remove an unnecessary developer.

A required number of ceramic laminated green sheets on which a predetermined pattern such as a conductor pattern is formed as described above are overlapped, and heat is applied at a temperature of about 90 to 130 ° C. and a pressure of about 50 to 200 kg / cm ^2. Pressure bonding is performed to produce a multilayer sheet substrate. After that, the ceramic multilayer substrate can be manufactured by firing the multilayer sheet substrate in an appropriate firing atmosphere and firing temperature according to the types of the ceramic laminated green sheet and the conductor powder used therein.

[0024]

EXAMPLES The present invention will be specifically described below with reference to Examples and Comparative Examples, but it goes without saying that the present invention is not limited to the following Examples. In the following, "part" and "%" are based on mass unless otherwise specified.

Example 1 <Preparation of Green Sheet as Lower Layer> The composition of glass-ceramic powder is 50% alumina powder with 96% purity and 50% silica silicate glass. The shelf silicate glass composition is S
_{iO 2: 54%, Al 2} O 3: 14%, CaO: 20%,
_{MgO: 2%, B 2 O} 3: 9%. As the glass-ceramic powder, a powder having an average particle diameter of 2.2 μm and a specific surface area of 1.5 m ² / g was finely powdered with an attritor in advance. Next, to 100 parts of this glass-ceramic powder, 12 parts of polyvinyl butyral resin (BM-2 manufactured by Sekisui Chemical Co., Ltd.) as a binder and DOP as a plasticizer.
2 parts of (dioctyl phthalate), sorbitan fatty acid ester (manufactured by Kao Corporation: SP-030) 2 as a dispersant
Parts, a toluene / 2-propanol mixed solution (volume ratio 50/50) as an organic solvent is mixed at a predetermined ratio and mixed well, and mixed with an attritor mill (using a zirconia ball having a diameter of 5 mm) for 5 hours, followed by vacuum degassing. It foamed and prepared the slurry. The slurry thus prepared was applied to a carrier film by a doctor blade method and dried to prepare a ceramic green sheet as a lower layer of 300 μm in thickness. <Preparation of Slurry for Producing Top Layer> As the glass-ceramic powder, a glass-ceramic powder having the same composition as the glass-ceramic powder used for producing the lower layer green sheet was used. Next, 100 parts of this powder, 12 parts of acrylic resin (Koreisha Chemical Co., Ltd .: Oricox KC-800) as a binder, 2 parts of DOP (dioctyl phthalate) as a plasticizer, and sorbitan fatty acid ester as a dispersant (Kao Corporation) (Manufactured by: SP-030) and 2 parts of a toluene / 2-propanol mixed solution (volume ratio 50/50) as an organic solvent are mixed at a predetermined ratio and sufficiently mixed,
Further, the mixture was mixed with an attritor mill (using a zirconia ball having a diameter of 5 mm) for 10 hours and degassed in vacuum to prepare a slurry. <Production of Ceramic Laminated Green Sheet> Next, the above-mentioned ceramic slurry for the uppermost layer is applied onto the lower ceramic green sheet having a thickness of 300 μm by a doctor blade method and dried to form an uppermost layer having a film thickness of 30 μm. A ceramic laminated green sheet having two layers was formed.

Example 2 A two-layer ceramic laminated green sheet was produced in the same manner as in Example 1 except that 20 parts of acrylic resin was used as the binder of the slurry for producing the uppermost layer.

Comparative Example 1 The lower layer green sheet produced in Example 1 was used as a comparative example.

Application Example A conductive pattern was formed on the ceramic laminated green sheets prepared in Examples 1 and 2 and the ceramic green sheet prepared in Comparative Example 1 by the method described below.
The unexposed area after development was microscopically observed for the presence of residues. In addition, a green sheet having a pattern formed by the method described below was fired, and the presence or absence of delamination was visually observed. The results are summarized in Table 1. As is clear from the results shown in this table, according to the ceramic laminated green sheet of the present invention, it is possible to form a good fine pattern without the occurrence of a residue during development or delamination during firing. You can Further, according to the present invention, a fine pattern having a line width / width interval of 20 μm / 30 μm or less could be obtained by a photolithography method using a photosensitive conductive paste. Moreover, after firing, a conductor pattern without disconnection was obtained.

<Formation and Firing of Conductive Pattern> (a) The photosensitive conductive paste was prepared by the following method. As powder components of the paste composition, 97% of conductive powder (spherical silver powder, specific surface area 0.8 m ² / g) and glass frit (glass composition SiO ₂ : 54%, Al ₂ O ₃ : 14).
%, CaO: 20%, MgO : 2%, B 2 O 3: 9%, an average particle diameter of 0.9 .mu.m, powder having a specific surface area of 6.9m ² / g) 3
% Mixed powder was used. Next, to 550 parts of this mixed powder, a solution prepared by dissolving 100 parts of an acrylic copolymer-modified polymer having a carboxyl group composed of methacrylic acid and methyl methacrylate as a binder in ethyl carbitol acetate, and trimethylolpropane trimethacrylate 20 as a monomer. Part, dipentaerythritol hexaacrylate 20 parts, as a photopolymerization initiator 2-
Methyl-1- [4- (methylthio) phenyl] -2-morpholinoaminopropanone-1 10 parts and 2,4-diethylthioxanthone were mixed and mixed well, and then further mixed and dispersed with three rollers. A photosensitive conductive paste was prepared. (B) Coating film formation The above-mentioned photosensitive conductive paste was applied to each of the ceramic laminated green sheets prepared in Examples 1 and 2 and the ceramic green sheet prepared in Comparative Example 1 using a 250 mesh polyester screen. The whole surface was printed under a yellow lamp and kept at 80 ° C. for 20 minutes to be dried. The thickness of the coating film after drying was adjusted to about 20 μm. (C) Exposure The coating film formed as described above is exposed to 200 mJ / from the upper surface using a chrome mask having a fine pattern.
It was exposed to ultraviolet light with an ultrahigh pressure mercury lamp with an output of cm ² . (D) Development Next, it was immersed in a 0.4% aqueous solution of sodium carbonate at 25 ° C. for development, and thereafter, the portion which had not been photocured was washed with water using a spray. (E) The coating film printed on the fired ceramic laminated green sheet was held in the atmosphere at 450 ° C. for 1 hour to remove the binder, and then fired at 900 ° C. for 1 hour to obtain a ceramic substrate.

[0030]

[Table 1]

[0031]

As described above, the ceramic laminated green sheet of the present invention comprises a laminated body of a plurality of layers of ceramic green sheets, and the binder contained in at least the uppermost layer is better than the binder contained in other layers. Since it is also made of an excellent solvent resistance, the conventional ceramic green sheet is coated with a photosensitive paste, dried, and no residue is generated when developed, or delamination during firing, etc., Various high-definition and good patterns such as conductor patterns and resistor patterns can be efficiently formed by the photolithography method. In addition, since a pattern can be formed on the ceramic laminated green sheet using a photosensitive paste, a ceramic multilayer substrate having various patterns such as a fine conductor pattern of L / S = 20 μm / 30 μmm and a resistor pattern can be simultaneously formed. It can be formed by firing. As a result, it is possible to further reduce the size and increase the density of the ceramic multilayer substrate.

   ─────────────────────────────────────────────────── ─── Continued front page    (72) Inventor Satoshi Ozawa             Saitama Prefecture Hiki-gun Arashiyama-cho Oza Oita             Yo Ink Manufacturing Co., Ltd. Arashiyama Office F term (reference) 4G030 AA07 AA08 AA35 AA36 AA37                       CA03 CA08 GA20 PA21 PA22

Claims (3)

[Claims] 1. A laminated body of a plurality of layers of ceramic green sheets, wherein the binder contained in at least the uppermost layer is more excellent in solvent resistance than the binder contained in the other layers. Ceramic laminated green sheet. 2. The ceramic laminated green sheet according to claim 1, wherein the binder contained in the uppermost layer comprises a copolymer of (meth) acrylic acid ester and its derivative. 3. The ceramic laminated green sheet according to claim 1 is coated with a photosensitive paste, dried, and then selectively exposed in a predetermined pattern, and then developed. A method for forming a pattern on a ceramic laminated green sheet.