JP2002167232A - Glass powder and glass powder composition - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide glass powder and a glass powder composition enabling to produce a very thin and flat green sheet for electronic parts generating no crack nor streak, and having no defects such as unevenness on the surface. SOLUTION: This glass powder comprises borosilicate glass and has maximum particle size of 20 μm or below, D50/D10-a ratio of 50% particle size D50 to 10% particle size D10 of 3.1 or below and an amount of boric acid adhered on the surface of 0.6 mass% or below. The glass powder composition comprises the glass powder and a ceramic filler blended into the glass powder.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

The present invention relates to a glass powder and a glass powder composition used for producing a green sheet for electronic parts.

[0002]

2. Description of the Related Art Generally, green sheets are used for manufacturing electronic component substrates such as a multilayer substrate and a dielectric chip. As shown in FIG. 2, a green sheet forming apparatus using a doctor blade method is used for producing a green sheet. In this apparatus, a carrier film 1 is pulled out from a supply roll 1a and conveyed over a plurality of support rollers 2. A doctor blade 3a is provided above the carrier film 1, and glass powder or a ceramic filler is mixed with the glass powder. A coater unit 3 for storing a slurry 4 prepared from the glass powder composition, the organic binder, the organic solvent and the like is provided. When forming a green sheet, the slurry 4 in the coater unit 3 is applied from the gap 3b between the doctor blade 3a and the carrier film 1 with the movement of the carrier film 1 to form a slurry 4a in the form of a sheet, which is dried. The green sheet 10 is dried by the unit 5, and then the green sheet 10 is pulled out together with the carrier film 1 by a pair of draw-out rollers 6 a and 6 b and wound up on a take-up roll 11.

[0003] When producing the glass powder used for the slurry 4, the molten glass is first solidified and roughly pulverized into a cullet having an appropriate particle size, and then finely pulverized to obtain a glass powder having a required particle size. In particular, very thin green sheets are used for small or thin multilayer boards for electronic components and dielectric chips, and the glass powder used for these green sheets has a maximum particle size of 20 μm or less. Finely pulverized to a particle size distribution of

It is known that borosilicate glass releases boric acid from glass components during grinding. Therefore, as the fine pulverization method, a wet pulverization method using a lower alcohol such as ethanol as a pulverizing medium, which can chemically react most of the free boric acid with a lower alcohol and volatilize and remove as a borate ester, is generally used. Can be

[0005]

However, when pulverized by a wet pulverization method so that the maximum particle size becomes 20 μm or less, an undesired fine powder is generated in large quantities and the specific surface area of the glass powder is increased. When a slurry for a green sheet is produced using glass powder containing a large amount of fine powder and having a large specific surface area as a raw material, the viscosity of the slurry becomes extremely high, and sheet molding becomes difficult. To solve this, a method of adding a large amount of diluting solvent to the viscosity suitable for molding to reduce the viscosity can be taken, but the drying shrinkage of the green sheet in the drying process after sheet molding becomes too large, so the green sheet surface Green sheets without defects due to cracks and streaks cannot be obtained.

On the other hand, as a pulverization method capable of obtaining a powder having a small particle size distribution, there is a dry pulverizer such as a jet mill having a classifier in the pulverizer.

However, when borosilicate glass is pulverized by these dry pulverizers, boric acid in the glass component is released from a new interface of fine particles generated by the pulverization, and all the released boric acid is removed from the surface of the powdered glass. Adheres to In the case where a slurry for a green sheet is prepared from a glass powder having a considerable amount of free boric acid attached to the glass surface as a raw material,
As shown in FIG. 3, countless streaks of convex portions 10a and concave portions 10b and local concave portions 10c are formed on the surface of the formed green sheet 10. These irregularities become surface defects of the substrate when the electronic component substrate is manufactured, and thus there is a problem that such a green sheet 10 becomes defective.

The present invention solves the above-mentioned conventional problems and provides a glass powder and a glass powder composition capable of efficiently producing a very thin and smooth green sheet for electronic parts without cracks, streaks, or surface irregularities. The purpose is to provide things.

[0009]

The glass powder according to the present invention is made of borosilicate glass and has a maximum particle size of 20 μm.
D50 / D10, which is the ratio of 50% particle diameter D50 to 10% particle diameter D10, is 3.1 or less, and the amount of boric acid attached to the surface is 0.6% by mass or less. And

The amount of boric acid adhering to the glass powder surface is as follows:
If it is less than 0.6% by mass and exceeds 0.3% by mass, although the slurry does not gel completely, it still tends to slightly gel, and a smooth green sheet without irregularities is obtained. Method and conditions are extremely limited. Therefore, it is preferable to reduce the amount of boric acid adhered to the surface to 0.3% or less by further reducing the fine powder in the glass powder or increasing the compounding ratio of the ceramic filler.

As borosilicate glass, 10 to 30% of B ₂ O ₃ , 65 to 85% of SiO ₂ , R ₂ O +
RO 0-5% (R is an alkali metal element such as K or Mg)
Any composition can be used.

The glass powder composition of the present invention is made of borosilicate glass, has a maximum particle size of 20 μm or less,
D50 / is the ratio of 50% particle diameter D50 to 10% particle diameter D10.
It is characterized by comprising a glass powder having a D10 of 3.1 or less and an amount of boric acid adhering to the surface of 0.6% by mass or less, and a ceramic filler mixed with the glass powder.

As the ceramic filler, alumina,
Silica, cordierite, α-quartz, mullite, cristobalite, garnite, forsterite, enstatite, zircon, zirconia, and the like can be used, and a suitable ceramic filler may be selected or used in combination depending on the application. The ceramic filler preferably has a maximum particle diameter of 20 μm or less for producing a thin green sheet, and has a particle size distribution substantially equal to that of glass powder.

[0014]

The glass powder and the glass powder composition according to the present invention have a particle size distribution in which the glass powder is made of borosilicate glass and has a maximum particle size of 20 μm or less,
D50 / D10, which is the ratio of the particle diameter D50 to the 10% particle diameter D10, is 3.1 or less, and the particle size distribution of D50 or less is sharp and the amount of fine powder is small. Can be stably lowered.
Further, since the amount of boric acid adhering to the surface of the glass powder is 0.6% by mass or less, the slurry for a green sheet using such a glass powder or a glass powder composition does not exhibit thixotropic properties, and gelation occurs. However, the green sheet formed by the doctor blade method using this slurry is good without cracks, streaks, or surface irregularity defects.

[0015]

FIG. 1 is a graph showing an example of the particle size distribution of a glass powder according to an embodiment of the present invention. In the figure, the histogram is counted in each particle size section shown on the horizontal axis. Frequency percentage of powdered glass, line graph frequency%
, Respectively.

First, as Example 1 of the present invention, as a borosilicate glass, B ₂ O ₃ 20% by mass percentage and SiO ₂
Prepare a 75%, K ₂ O + MgO 5% composition,
After coarse pulverization into a cullet of an appropriate particle size, wet pulverization was performed using ethanol as a pulverizing medium, and further, a pulverized slurry was separated by settling to obtain only a glass powder having a desired particle size, and the fine powder was separated together with ethanol. This is put into a dryer, and most of the free boric acid is chemically reacted with a lower alcohol to volatilize and remove as a borate ester. As shown in FIG. Diameter D50 is 3.92 μm and 10% particle diameter D
10 is 1.41 μm, and the ratio D50 / D10 of D50 and D10 is 2.8.
In addition, a glass powder having a small amount of fine powder of 1.5 μm or less and a small amount of free boric acid having a surface adhering boric acid amount of 0.25% by mass was obtained.

In Example 2, a cullet of the same glass as in Example 1 was prepared, wet-milled similarly with ethanol, and ground slurry was obtained in the same manner as in Example 1 to obtain only a glass powder having a target particle diameter. After sedimentation, the fine powder was separated with ethanol. This was dried at a lower temperature than in the examples, and the maximum particle diameter and the 50% particle diameter D50 and 10% were determined.
% D10 / D10 which is the ratio of the particle diameter D10 is the same as that of the example, but the amount of boric acid adhering to the surface is 0.48% by mass, and a glass powder in which boric acid adheres slightly to the powder surface was obtained. .

As Comparative Example 1, a cullet of the same glass as in the example was prepared, and wet crushing was performed using ethanol.
By drying this pulverized slurry, the maximum particle size and boric acid adhering to the surface are the same as those in the example, but the 50% particle diameter D50 is 3.89 μm and the 10% particle diameter D10 is 1.17 μm.
m, a glass powder containing a large amount of fine powder having a ratio D50 / D10 of D50 / D10 of 3.3 to 1.5 μm or less was obtained.

As Comparative Example 2, a cullet of the same glass as in the example was prepared, and dry crushed using a jet mill.
D50 / D10, which is the ratio of the maximum particle diameter to the 50% particle diameter D50 and the 10% particle diameter D10, is the same as that of the embodiment, but the amount of boric acid adhered to the surface is 0.72% by mass, and boric acid adheres to the powder surface. A glass powder with a large content was obtained.

A slurry 4 was prepared by blending a solvent such as an alumina powder filler, an acrylic binder, a plasticizer, an alcohol, and a ketone with each of the glass powders of Examples 1 and 2 and Comparative Examples 1 and 2. Was supplied to the coater section 3 of the green sheet forming apparatus shown in FIG. 2 to produce a green sheet 10, and the film forming properties and the appearance of the green sheet of Examples and Comparative Examples 1 and 2 were observed.

The slurry for a green sheet using the glass powder of Example 1 did not show a significant increase in viscosity and thixotropic properties and had good film-forming properties.
A smooth green sheet free of cracks and stripes and having no irregularities on the surface was obtained.

The green sheet slurry using the glass powder of Example 2 did not become a gel, but became a slurry having a slightly poor fluidity. When this was deposited on a green sheet, if the production process was in a stable state, a smooth green sheet free of cracks and streaks and having no irregularities on the surface was obtained. However, when a slight disturbance such as a disturbance in the supply speed of the slurry is applied, stripes are generated on the formed green sheet, and it is difficult to obtain a stable and good green sheet.

On the other hand, the viscosity of the green sheet slurry using the glass powder of Comparative Example 1 was significantly increased, and a slurry having a viscosity suitable for film formation could not be obtained unless diluted with a large amount of solvent. Was. Further, when a green sheet was formed into a film using a slurry adjusted to a predetermined viscosity by dilution, many cracks and streaks occurred on the surface.

Further, the slurry for a green sheet using the glass powder of Comparative Example 2 exhibited a thixotropic property and became a gel, and when a film was formed on the green sheet, countless irregular defects were generated on the surface.

The particle size distribution of the glass and the 50% particle diameter D
The value of 50 and the value of 10% particle diameter D10 were measured using a laser diffraction particle size distribution analyzer "Microtrack SPA" manufactured by Nikkiso Co., Ltd.

The amount of boric acid adhering to the surface of the glass powder is determined by dispersing the glass powder in pure water and adding a considerable amount of a polyhydric alcohol such as mannitol to form a complex boric acid compound. This complex borate compound is converted to Na with a known normality.
It was measured by a neutralization titration method in which the content was neutralized and quantified from OH.

In the above embodiment, the glass powder and the ceramic filler are compounded after being individually pulverized. However, the ceramic filler is put into a pulverizer for pulverizing the glass cullet and the glass and the ceramic filler are mixed. Grinding and mixing may be performed simultaneously.

[0028]

According to the present invention, a glass powder composed of borosilicate glass having a small amount of undesired fine powder and a small amount of free boric acid adhering to the surface of the glass powder, and a glass powder composition using such a glass powder Can be provided, so that a very thin and smooth green sheet free from cracks and streaks and having no defects such as unevenness on the surface can be obtained, which is a practically excellent effect.

[Brief description of the drawings]

FIG. 1 is a graph showing an example of the particle size distribution of the glass powder of the present invention.

FIG. 2 is an explanatory view of a green sheet forming apparatus.

3A and 3B are explanatory views of a green sheet manufactured using a conventional glass powder, wherein FIG. 3A is a cross-sectional view of the conventional green sheet, and FIG. 3B is an explanatory view of a surface defect of the conventional green sheet.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 1 Carrier film 2 Support roller 3 Coater part 3a Doctor blade 4 Slurry 5 Drying part 6a, 6b Pull-out roller 10 Green sheet

 ──────────────────────────────────────────────────続 き Continued on the front page F term (reference) 4G062 AA09 AA15 BB05 DA06 DA07 DB01 DC04 DD01 DE01 DF01 EA01 EA02 EA03 EA10 EB01 EB02 EB03 EC01 EC02 EC03 ED01 ED02 ED03 EE01 EE02 EE03 EF01 EF01 EF03 EF01 EF03 FE01 FF01 FG01 FH01 FJ01 FK01 FL01 GA01 GA10 GB01 GC01 GD01 GE01 HH01 HH03 HH05 HH07 HH09 HH11 HH13 HH15 HH17 HH20 JJ01 JJ03 JJ05 JJ07 JJ10 KK01 KK03 KK05 KK07 PP15 PP06 PP15

Claims (4)

[Claims] 1. A borosilicate glass having a maximum particle diameter of 20 μm or less, a ratio of 50% particle diameter D50 to a 10% particle diameter D10 of D50 / D10 of 3.1 or less, and a surface A glass powder characterized in that the amount of adhering boric acid is 0.6% by mass or less. 2. The glass powder according to claim 1, wherein the amount of boric acid attached to the surface is 0.3% by mass or less. 3. A borosilicate glass having a maximum particle diameter of 20 μm or less, a ratio of 50% particle diameter D50 to a 10% particle diameter D10 of D50 / D10 of 3.1 or less, and a surface A glass powder composition comprising: a glass powder having an attached boric acid amount of 0.6% by mass or less; and a ceramic filler mixed in the glass powder. 4. The glass powder composition according to claim 3, wherein the amount of boric acid attached to the surface is 0.3% by mass or less.