Compositions: ceramic – Ceramic compositions – Glass compositions – compositions containing glass other than...
Reexamination Certificate
2000-05-31
2002-03-26
Group, Karl (Department: 1755)
Compositions: ceramic
Ceramic compositions
Glass compositions, compositions containing glass other than...
C501S017000, C501S032000, C501S077000, C501S078000, C501S079000
Reexamination Certificate
active
06362119
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a barium borosilicate glass and a glass ceramic composition useful for insulating pastes for electronic parts, ceramic color pastes for automobile windows, glazes for dishes and the like.
2. Discussion of Background
A glass powder or a glass ceramic composition containing a glass powder is widely used for e.g. insulating pastes for electronic parts and ceramic color pastes for automobile windows. Hereinafter, the glass powder and the glass ceramic composition will be referred to as a glass frit.
A glass frit for the above applications is required to have various properties, and various glass frits are used depending upon the properties required. For example, a glass frit containing lead, bismuth or cadmium has been conventionally used as a glass frit having excellent water resistance and acid resistance and capable of being fired at a temperature of from 600 to 850° C.
In recent years, as a glass frit having such properties, one containing no lead, bismuth nor cadmium has been required.
SUMMARY OF THE INVENTION
It is an object of the present invention to provide a glass and a glass ceramic composition containing no lead, bismuth nor cadmium, and having a softening point and a thermal expansion coefficient suitable for various applications, particularly for an application wherein a chemical durability such as water resistance is required and the firing temperature is from 600 to 850° C.
The present invention provides a barium borosilicate glass which consists essentially of, as represented by wt %:
B
2
O
3
5
to 35%,
SiO
2
0.5
to 30%,
BaO
25
to 75%,
Al
2
O
3
0.5
to 13%,
SnO
2
0
to 2%,
CeO
2
0
to 2%,
MgO + CaO + SrO
0
to 10%,
ZnO
0
to 20%,
TiO
2
0
to 5%,
ZrO
2
0
to 5%,
Li
2
O
0
to 5%,
Na
2
O
0
to 5%, and
K
2
O
0
to 5%,
and a glass ceramic composition which comprises, as represented by mass%, from 50 to 99.9% of a powder of said barium borosilicate glass, from 0 to 50% of a ceramic filler and from 0 to 30% of a heat resistant pigment, wherein the total content of the ceramic filler and the heat resistant pigment is from 0.1 to 50%.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS
The barium borosilicate glass of the present invention (hereinafter referred to simply as the glass of the present invention) is usually formed into a powder, followed by coating and firing to obtain a sintered product, and used as a powder.
The powder of the glass of the present invention may be kneaded with a vehicle containing a resin component such as ethyl cellulose and a solvent such as &agr;-terpineol to obtain a paste, which is used for e.g. screen printing. Otherwise, it may be formed into a slurry, which is then formed into a green sheet, and a multi-layer construction may be prepared by using said green sheet. Here, the multi-layer construction may, for example, be prepared in such a manner that e.g. an electronic circuit pattern is formed on the green sheet by e.g. screen printing, and the resulting green sheets are laminated, followed by firing.
The powder of the glass of the present invention is useful for e.g. insulating pastes for electronic parts, materials for sealing electronic parts, color pastes for automobile windows and glazes for dishes. Examples of the insulating pastes for electronic parts include overcoat pastes for hybrid IC (HIC), crossover pastes for HIC, multi-layer insulating glass pastes for HIC and overcoat pastes for print heads.
The glass of the present invention has a softening point (T
S
) i.e. a softening point by a differential thermal analysis of preferably from 600 to 800° C. If it is less than 600° C., softening flow tends to be too significant during firing at a temperature of from 600 to 850° C., even if e.g. a ceramic filler is used together. It is more preferably at least 630° C., particularly preferably at least 650° C. If it exceeds 800° C., softening flow tends to be too small during firing at a temperature of from 600 to 850° C. It is more preferably at most 770° C., particularly preferably at most 750° C.
It is preferred that the glass of the present invention is less likely to undergo crystallization during firing. Namely, the glass of the present invention has a crystallization temperature (T
C
) of preferably at least 950° C., or a difference between T
C
and T
S
(T
C
-T
S
) of preferably at least 50° C. (T
C
-T
S
) is more preferably at least 100° C., particularly preferably at least 130° C. Here, T
C
is a crystallization peak temperature obtained by a differential thermal analysis, and in a case where no crystallization peak is confirmed even if the differential thermal analysis is carried out up to 1,000° C., T
C
is assumed to be infinite (∞).
The average coefficient of linear expansion of the glass of the present invention at a temperature of from 50 to 350° C., i.e. the above average coefficient of linear expansion of the sintered product of the powder of the glass of the present invention, is preferably from 55×10
−7
to 100×10
−7
/° C. If it is less than 55×10
−7
/° C., expansion coefficient matching with e.g. an AlN substrate having the above average coefficient of linear expansion of, for example, 45×10
−7
/° C., tends to be difficult, whereby application in which coating on e.g. an AlN substrate and firing are carried out, tends to be difficult. If it exceeds 100×10
−7
/° C., expansion coefficient matching with e.g. soda lime silica glass having the above average coefficient of linear expansion of, for example, 78×10
−7
/° C., tends to be difficult, even if e.g. a filler is used together, whereby application in which coating on e.g. a soda lime silica glass and firing are carried out, tends to be difficult. It is more preferably at most 85×10
−7
/° C. Hereafter the average coefficient of linear expansion at a temperature of from 50 to 350° C. will be referred to simply as expansion coefficient.
The glass of the present invention preferably consists essentially of, as represented by mass% based on the following oxides:
B
2
O
3
5
to 35%,
SiO
2
0.5
to 30%,
BaO
25
to 75%,
Al
2
O
3
0.5
to 13%,
SnO
2
0.2
to 2%,
CeO
2
0
to 2%,
MgO + CaO + SrO
0
to 10%,
ZnO
0
to 20%,
TiO
2
0
to 5%,
ZrO
2
0
to 5%,
Li
2
O
0
to 5%,
Na
2
O
0
to 5%, and
K
2
O
0
to 5%.
Now, the composition of the glass of the present invention will be described below, representing by mass%.
B
2
O
3
is a network former and essential. If it is less than 5%, the softening point tends to be too high. It is preferably at least 7%, more preferably at least 8%. If it exceeds 35%, the chemical durability, particularly water resistance, will decrease. It is preferably at most 33%.
SiO
2
is a network former and essential. If it is less than 0.5%, the chemical durability, particularly water resistance, will decrease. It is preferably at least 0.7%, more preferably at least 5%, particularly preferably at least 6%. If it exceeds 30%, the softening point tends to be too high. It is preferably at most 28%, more preferably at most 26%.
The total of contents of B
2
O
3
and SiO
2
is preferably at most 49%, more preferably at most 47%.
BaO is a flux component and essential. If it is less than 25%, the softening point tends to be too high. It is preferably at least 27%, more preferably at least 28%. If it exceeds 75%, the glass tends to be devitrified during melting. It is preferably at most 73%, more preferably at most 71%.
Al
2
O
3
is an essential component to increase the chemical durability, particularly water resistance and/or acid resistance, and to suppress crystallization during firing. If it is less than 0.5%, its effect, i.e. the effect of increasing the chemical durability or the effect of suppressing crystallization during firing, tends to be too small. It is preferably at least 0.7%, more preferably at least 1%. If it exceeds 13%, the glass tends to be devitrified during melting. It is preferably at most 11%, more preferably at most 10%, particularly preferably at most 6%.
SnO
2
is not essen
Asahi Glass Company Limited
Group Karl
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