JPH09169559A - Manufacturing method of green sheet for ceramic substrate - Google Patents

Abstract

(57) 【Abstract】 PROBLEM TO BE SOLVED: When an acrylic resin is added as a binder at the time of producing a green sheet composed of an alkali silicate glass and a filler, the slurry is apt to gel, cracks occur in the sheet, and filling of the green sheet. There was a problem that the rate decreased. SOLUTION: In a method for preparing a slurry in which a binder made of an acrylic resin and a solvent are added to a mixed powder of an alkali silicate glass powder and a ceramic powder, and shaping the slurry into a sheet to produce a green sheet, the alkali silicate glass is used. Has a BET specific surface area of 0.5 to 3 m
A glass powder having a water content of ² / g and a water content of 15,000 ppm or less is used.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method for manufacturing a green sheet for a ceramic substrate, which is made of glass ceramics and is useful as an insulating substrate for a multilayer wiring substrate or a package for housing a semiconductor element.

[0002]

2. Description of the Related Art Generally, a green sheet for a ceramic substrate can be obtained by uniformly placing a slurry containing ceramic powder on a film by a doctor blade method and drying the slurry. In addition to ceramic powder, an organic binder, a plasticizer, a solvent, etc. are added to this slurry.

PVB (polyvinyl butyral) has been generally used as an organic binder to be added to ceramic powder, but when PVB is degreased in a non-oxidizing atmosphere, thermal decomposability occurs. Since residual carbon causes problems such as poor appearance and poor electrical properties, the use of acrylic resins, which have excellent thermal decomposability, is shifting to use in recent years, and in particular acrylic resins having a carboxyl group as a functional group. Is known to have excellent dispersibility.

Recently, as a low temperature firing substrate material which can be fired simultaneously with a wiring layer made of Cu having good electric conductivity,
A so-called glass-ceramic substrate has been developed in which a mixture of glass powder and ceramic filler powder is molded to produce a green sheet, which is fired. Even when producing the green sheet for the glass ceramic substrate, an acrylic resin is generally used as the organic binder.

However, conventional glass ceramics are
Strength is low, if it is mounted on an external electric circuit board of the organic resin, there is such an electrical connection failure is caused by stress due to difference in thermal expansion coefficient in question, whereas, the applicant, Li ₂ We have proposed a glass-ceramic material with high strength obtained by adding an alkali silicate glass containing an alkali metal such as O and filler powder such as forsterite and firing it to precipitate an alkali metal silicate.

[0006]

However, when a green sheet for a glass-ceramic substrate is manufactured, an acrylic resin having a thermally decomposable property, for example, a carboxyl group as a functional group is used as an organic binder and the above-mentioned glass raw material powder is used. When such an alkali silicate glass is adopted, interaction occurs between the carboxyl group of the functional group in the acrylic resin and the cation of the alkali component in the glass,
As a result, the slurry is easily gelled, the dispersibility of the slurry is lowered, cracks occur in the sheet, the filling rate of the green sheet is reduced, the yield of the product is reduced due to variations in firing shrinkage, etc. There was a problem.

[0007]

Means for Solving the Problems As a result of repeated studies on the above problems, the present inventors have found that alkali silicate glass has a higher water content because it easily dissolves water vapor during the manufacturing process as compared with alumina. Many, its water content tends to increase as the specific surface area of glass increases, and by controlling the specific surface area of the alkali silicate glass powder to be used and controlling the water content in the powder to a low level, the slurry gel The present invention has been completed by finding out that it is possible to prevent aging.

That is, in the present invention, a slurry is prepared by adding a binder made of an acrylic resin and a solvent to a mixed powder of an alkali silicate glass powder and a ceramic powder, and molding the slurry into a sheet to produce a green sheet. In the method, the alkali silicate glass has a BET specific surface area of 0.5 to ³ m ² / g and a water content of 15000 ppm.
It is characterized by the following, and the yield point of the alkali silicate glass powder is 400 ° C to 800 ° C.

[0009]

According to the present invention, when a green sheet is produced by using a mixture of an alkali silicate glass powder and a filler powder, the BET specific surface area of the alkali silicate glass powder is set to 0.5 to 3 m ² / g and the BET specific surface area is set to 0.5 to 3 m ² / g. The amount of water is 15,000p
By setting it to be pm or less, ionization of the carboxyl group due to water of the acrylic resin containing the carboxyl group is suppressed, the filling rate of the sheet can be increased without gelation of the slurry, and cracks in the sheet are generated. It is possible to prevent it, and to significantly improve the yield at the time of manufacturing the green sheet. Thereby, the glass ceramic substrate can be manufactured at low cost.

[0010]

BEST MODE FOR CARRYING OUT THE INVENTION According to the method for producing a glass-ceramic sintered body of the present invention, glass powder and filler powder are used as raw materials. According to the present invention, the glass powder is lithium silicate glass, Alkali silicate glass such as soda aluminum silicate glass is used.

The reason for using such an alkali silicate glass is that the coefficient of thermal expansion is about 13 in order to reduce the difference in thermal expansion when mounted on an organic resin-based external electric circuit board.
This is because by precipitating lithium silicic acid or soda aluminum silicic acid having a high thermal expansion coefficient of ppm / ° C., the glass ceramic sintered body itself is made to have high thermal expansion.

Further, according to the present invention, it is important that the BET specific surface area of the alkali silicate glass is 0.5 to ³ m ² / g. It has a water content of 1500
It is necessary to control to 0 ppm or less, and when the specific surface area is less than 0.5 m ² / g, a dense sintered body cannot be obtained after firing, and when the specific surface area exceeds 3 m ² / g, the glass is Since the water content of 1 is more than 15000 ppm, the slurry is apt to gel and the yield at the time of manufacturing the green sheet is reduced. In particular, it is desirable that the BET specific surface area of glass is 1 to 2.5 m ² / g and the water content is 10000 ppm or less. This water content tends to increase as the BET specific surface area increases. Therefore, in order to control the water content to 15000 ppm or less, the BET specific surface area is adjusted to 3 m ² / g or less by crushing glass. it can.

The glass powder has a yield point of 400.
It is desirable that the temperature is from ℃ to 770 ℃. This is because when molding a mixture consisting of glass and filler, a molding binder such as an organic resin is added, but this binder is removed efficiently and the baking conditions are matched with the metallization that is baked at the same time as the insulating substrate. When the yield point is lower than 400 ° C., the glass starts to be sintered at a low temperature. For example, the sintering start temperature of Ag, Cu or the like is about 600 to 800 ° C. This is because the co-firing is not possible, and the densification of the molded body starts at a low temperature, so that the binder cannot be decomposed and volatilized, and the binder component remains to affect the properties. On the other hand, if the yield point is higher than 770 ° C., it becomes difficult to sinter unless the glass content is increased to 50% by volume or more. Therefore, a large amount of expensive crystalline glass is required, which increases the cost of the sintered body. It will be. Preferably the yield point is 4
It is 00-650 degreeC.

Specific examples of the glass used in the present invention include alkali metal oxides such as Li ₂
Alkali silicate glass containing O or Na ₂ O in an amount of 5 to 30% by weight, particularly 5 to 20% by weight is used, but in order to increase the strength, it is preferable to form an alkaline silicic acid or an alkali aluminum silicic acid. in order to, SiO ₂
Is present in an amount of 60 to 85% by weight in the total amount of glass, and Si
65 to 95% by weight in total of O ₂ and alkali metal oxide
In addition, Al ₂ O ₃ , MgO, TiO ₂ , Na
Alkali silicate type glass containing at least one of ₂ O, K ₂ O, ZnO, P ₂ O ₅ , F, CaO, etc., especially crystallized glass capable of precipitating alkali silicic acid or alkali aluminum silicic acid during the sintering process is used. Is desirable. It is desirable that B ₂ O ₃ be 1% by weight or less in these glasses. Further, the linear thermal expansion coefficient of the glass powder used at 40 ° C to 400 ° C is 6 to 18 ppm / ° C, particularly 7 to 13 p.
It is preferably pm / ° C.

The content of the alkali metal oxide in the glass is limited to the above range. When the content is less than 5% by weight, the amount of alkali silicic acid crystals produced during firing is small, resulting in high strength and high thermal expansion. This is because good characteristics as a substrate cannot be expected, for example, when the content is more than 30% by weight, the dielectric loss exceeds 100 × 10 ⁻⁴ .

On the other hand, as the filler powder to be mixed with the above glass powder, alumina, silica, quartz, quartz, cristobalite, forsterite, mullite, magnesia, petalite, spinel, wollastonite, nepheline, enstatite, garnite, etc. Among these, forsterite (2MgO.SiO ₂ , linear thermal expansion coefficient 1 as a metal oxide having a linear thermal expansion coefficient of 6 ppm / ° C. or more at 40 ° C. to 400 ° C.
0ppm / ℃), quartz (SiO ₂ , linear thermal expansion coefficient 1
5 ppm / ° C), cristobalite (SiO ₂ , linear thermal expansion coefficient 20 ppm / ° C), wollastonite (CaO.
SiO ₂ , linear thermal expansion coefficient 9 ppm / ° C.), petalite (LiAlSi ₄ O ₁₀ , linear thermal expansion coefficient 8 ppm / ° C.),
Magnesia (MgO, linear thermal expansion coefficient 9ppm / ° C), nepheline (Na ₂ O · Al ₂ O ₃ · SiO ₂ , linear thermal expansion coefficient 9ppm / ° C), alumina (Al ₂ O ₃ , linear thermal expansion coefficient 7ppm / ° C) ) And the like, the linear thermal expansion coefficient of the entire sintered body is 8 to 18 ppm / ° C.
It becomes possible to easily control in the range of.

When the thermal expansion coefficient of each powder deviates from the above range as described above, a difference in thermal expansion between the glass powder and the ceramic powder occurs, which causes a decrease in strength of the sintered body. If the linear thermal expansion coefficient of the ceramic powder is less than 6 ppm / ° C, it may be difficult to set the linear thermal expansion coefficient of the sintered body to 8 to 18 ppm / ° C.

The alkali silicate glass powder and the filler powder are mixed in a ratio of 20 to 80% by volume of glass powder and 80 to 20% by volume of filler powder. This is because the glass used in the present invention has a shrinkage initiation temperature of 700 ° C. or lower without addition of a filler, and part of the glass melts at 800 ° C. or higher, so that it is difficult to simultaneously form a metallized wiring layer. Is. However, by mixing glass powder in a ratio of 20 to 80% by volume and filler powder in a ratio of 80 to 20% by volume, a liquid phase for crystal precipitation and liquid phase sintering of the filler component is formed at a firing temperature. You can Further, since the shrinkage start temperature of the entire molded body can be raised, it is possible to match the simultaneous firing conditions with the metallized wiring layer depending on the type of metallization used by adjusting the content of the filler.

The reason for limiting the amounts of the glass and the filler component to the above range is that the amount of glass is less than 20% by volume,
In other words, if the filler component is more than 80% by volume, a sufficient liquid phase will not be generated even if the above-mentioned glass is used, and therefore it is necessary to fire at a high temperature. In that case, the metallization melts in the metallization simultaneous firing. Also, the glass is 8
If it is more than 0% by volume, in other words, if the filler component is less than 20% by volume, the properties of the sintered body will largely depend on the properties of the glass, making it difficult to control the material properties and lowering the sintering start temperature. Therefore, there arises a problem that it cannot be fired at the same time as the wiring conductor, and the cost of the raw material also increases.

Further, in order to reduce the raw material cost, it is preferable to reduce the content of expensive glass, and particularly 20 to 50% by volume of glass powder, 50 to 80% by volume of filler powder, and further 20 to 40% by volume of glass powder. The filler powder is preferably 60 to 80% by volume.

In the above-mentioned composition, it is desirable that the amount of the filler component is appropriately adjusted according to the yield point of glass. That is, the yield point of glass is 400 ° C to 65 ° C.
When the temperature is as low as 0 ° C., the sinterability at low temperature is enhanced, so that the content of the filler can be relatively large, 50 to 80% by volume.
On the other hand, the yield point of crystalline glass is 650 ° C to 77 ° C.
When the temperature is as high as 0 ° C., the sinterability is lowered, so that it is desirable to mix the filler in a relatively small amount of 20 to 50% by volume.

In order to produce a green sheet for producing a wiring board using the above glass powder and filler powder, a suitable organic resin binder, a plasticizer and a solvent are added to the mixed powder mixed in the above ratio. Add and mix to prepare a slurry.

An acrylic resin is used as the organic resin binder used. This is because the acrylic resin has good decomposition and removal properties and little carbon residue when the binder is removed in a non-oxidizing atmosphere when co-firing with Cu or the like as compared with other organic resins. Is.
Further, by having a carboxyl group as a functional group, the dispersibility of the ceramic powder can be improved. As specific acrylic resins, acrylic resins, acrylic acid ester copolymers, methacrylic acid ester copolymers, acrylic acid ester-methacrylic acid ester copolymers and the like are used, and as the monomers constituting these, Acrylic acid, methyl acrylate, ethyl acrylate, butyl acrylate, cyclohexyl acrylate,
2-ethylhexyl acrylate, methacrylic acid, methyl methacrylate, ethyl methacrylate, butyl methacrylate, cyclohexyl methacrylate, 2-methacrylic acid
Examples include ethylhexyl and the like.

By polymerizing a monomer having a carboxyl group with these monomers, an acrylic resin having a carboxyl group as a functional group can be obtained.

Further, as the plasticizer, it is desirable to select a plasticizer having high plasticization efficiency, that is, a plasticizer capable of exhibiting plasticity by addition in a small amount in order to avoid deterioration of flexibility of the green sheet. As a plasticizer satisfying this condition, adipates or phthalates may be used.

Further, as the solvent, aromatic solvents such as benzene, toluene, xylene, alcohol solvents such as methanol, ethanol, isopropyl alcohol (IPA), butanol, acetone, methyl ethyl ketone,
A ketone solvent such as methyl isobutyl ketone can be used alone or as a mixture.

These are 5 to 30% by weight of the above binder and 3% of the plasticizer to the glass-ceramic mixed powder.
A slurry can be prepared by mixing ˜20% by weight and a solvent in a ratio of 30 to 80% by weight and thoroughly mixing them with a ball mill or the like. The viscosity of the slurry at this time is 10
-50 poise is suitable.

Next, using the obtained slurry, a sheet-shaped molded body (green sheet) can be produced by a known method such as a doctor blade method, a press molding method, a rolling method, a calender roll method or the like. .

According to the present invention, the filling rate of the green sheet thus obtained, that is, the powder density of the green sheet with respect to the theoretical density of the powder is 50% or more, and the sheet has no cracks in appearance. It is necessary that cracks and the like do not occur, and if the filling rate is lower than 50%, firing shrinkage increases, so that non-defective sheets are selected by this filling rate and visual inspection.

In order to specifically manufacture a wiring board using this green sheet, a metal powder suitable for forming a wiring layer on the surface of the green sheet, for example, copper powder, and an organic binder, a plasticizer, A metallizing paste obtained by adding and mixing a solvent is applied by a screen printing method, an offset printing method or the like. Further, if necessary, through holes are formed and filled with a metallizing paste, and then a plurality of green sheets are laminated, pressure-bonded, and then fired.

Upon firing, the organic resin binder is first removed. When Cu is used as the wiring conductor, it is performed in a nitrogen atmosphere containing water vapor at 100 to 800 ° C. Subsequent firing is performed at 850 to 1050 ° C.
_2. Performed in a non-oxidizing atmosphere such as Ar. In particular, when metallization of Cu or the like and simultaneous firing are performed in the production of a wiring board, the yield point of the glass to be blended is 400 ° C to 65 ° C.
At 0 ° C., the content of the filler is preferably 50 to 80% by volume.

[0032]

【Example】

Example 1 As an alkali silicate glass, a weight ratio of lithium silicate glass 74% SiO ₂ -14% Li ₂ O-4% Al ₂ O ₃ -2
_{% P 2 O 5 -2% K} 2 O-2% ZnO-2% Na 2 O
(Yield point 480 ° C) Soda aluminum silicate glass 34% SiO ₂ -15% Na ₂ O-15% Al ₂ O _3-
17% P ₂ O ₅ -8% K ₂ O-11% ZnO (yield point 6
00 ° C.), a plurality of types of glass having different BET specific surface areas and water contents were prepared. The BET specific surface area of these glasses was measured by a gas adsorption method, and the water content was measured by a thermal desorption gas analysis method. Various filler powders were weighed and mixed with this glass so as to have the composition shown in Table 1.

Further, to 100 g of this mixed powder, 12 g of an organic resin of isobutyl methacrylate (i-BMA) or normal butyl methacrylate (n-BMA) containing a carboxyl group as a functional group, and dibutyl phthalate (DBP) as a plasticizer. 10 g, toluene as a solvent 55 g, and isopropyl alcohol 5 g were added, and mixed by a ball mill for 24 hours to form a slurry. The viscosity of the obtained slurry was measured at a shear rate of 10 S ^-1 . This slurry was made 0.2 by a doctor blade method.
A green sheet was produced by molding to a thickness of mm. As organic resins, Sample Nos. 1 to 14 were the above i-B.
MA and Sample Nos. 15 to 19 used the above n-BMA, respectively.

The filling rate of the obtained green sheet was evaluated. The filling rate was determined by cutting a green sheet into a square of 35 mm × 30 mm, measuring the thickness and weight to determine the green sheet density, and determining the filling rate from the specific gravity of the raw material powder. In addition, 20 sheets were prepared for each sample, and as a result of the appearance inspection of the sheets, the number of sheets where cracks were observed was examined. The results are shown in Table 1.

[0035]

[Table 1]

As is clear from the results in Table 1, samples Nos. 3, 6, 10 and 1 having a BET specific surface area of more than 3 m ² / g.
3, 14, 18, and 19 all have a water content of 15,000.
As a result, the viscosity of the slurry was as high as 50 poise or more, the filling rate was low, and many cracks were observed in the appearance inspection.

On the other hand, all of the samples of the present invention have a slurry viscosity of 50 poise or less and a filling rate of 50% or more, cracks are hardly observed, and a sheet having a high yield can be manufactured. there were.

Further, with respect to the green sheet of the present invention,
As a result of removing the binder in a nitrogen atmosphere at 730 ° C., no residual carbon was detected in any case, and the binder was excellent in decomposing and removing properties.

[0039]

As described in detail above, according to the present invention, in the production of a glass ceramic substrate composed of an alkali silicate glass and a filler, the specific surface area and the water content of the alkali silicate glass are controlled to improve the filling rate. A good green sheet without cracks can be obtained. Thereby, the yield at the time of manufacturing the green sheet can be improved and an inexpensive substrate can be manufactured.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Koichi Yamaguchi 1-4-4 Yamashita-cho, Kokubu-shi, Kagoshima

Claims (2)

[Claims] 1. A method for preparing a green sheet by preparing a slurry by adding a binder made of an acrylic resin and a solvent to a mixed powder of an alkali silicate glass powder and a ceramic powder, and molding the slurry into a sheet to produce a green sheet, BET specific surface area of alkali silicate glass is 0.5-3m
² / g, water content is 15000ppm or less, a method for producing a green sheet for a ceramic substrate. 2. The method for producing a green sheet for a ceramic substrate according to claim 1, wherein the acrylic resin contains a carboxyl group as a functional group.