Compositions: ceramic – Ceramic compositions – Glass compositions – compositions containing glass other than...
Reexamination Certificate
2000-05-17
2003-07-29
Bell, Mark L. (Department: 1755)
Compositions: ceramic
Ceramic compositions
Glass compositions, compositions containing glass other than...
C501S076000, C501S017000, C501S032000
Reexamination Certificate
active
06599851
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to a composition of a dielectric for a plasma display panel, and more particularly, to a composition of a material for barrier ribs physically separating discharge cells and a composition of a material for a dielectric thick film for a rear substrate of a plasma display panel.
2. Description of the Background Art
Recently, a research and development for flat panel display apparatuses such as a liquid crystal display (LCD), a field emission display(FED) or a plasma display panel(PDP) is actively being conducted. Especially, the PDP is the most remarkable owing to its advantages in that it is easily produced due to its simple structure, a memory function, and a wide view angle more than 160° is attained, and a large screen more than 40 inches can be implemented.
FIG. 1
is a schematic view showing a structure of a plasma display panel in accordance with a conventional art.
As shown in the drawing, the plasma display panel includes two pieces of flat panels
10
and
20
horizontally disposed to each other, and discharge cells
30
formed to be sealed between the flat panels
10
and
20
.
In detail, address electrodes
11
are formed on the upper surface of the rear substrate
10
, and a lower dielectric thick film
12
for charging a wall charge is formed on the upper surface of the address electrodes
11
and on the rear substrate
10
. Barrier ribs
13
are formed on the upper surface of the lower dielectric thick film
12
with the address electrodes
11
therebetween. The barrier ribs
13
serve to compart physically the discharge cells
30
. Florescent materials
14
are coated on the wall side of the barrier ribs
13
and on the upper surface of the lower dielectric thick film
12
.
Meanwhile, transparent electrodes
21
are formed at one face of the front substrate
20
placed at the upper position of the rear substrate
10
, and the upper dielectric thick film
22
is coated on the one face of the front substrate
20
and the transparent electrodes
21
. A protective film
23
is coated on the surface of the upper dielectric thick film
22
.
In the conventional art, the barrier ribs are fabricated by LTCCM (low temperature cofired ceramic on metal) method that is favorable to obtain a high aspect ratio. That is, after fabricating a green sheet, the green sheet is attached on the upper surface of the rear substrate for a plasma display panel, on which a predetermined metal mold is mounted and pressurized with an uniform pressure to mold a barrier rib form. And then, the metal mold is removed, and the thusly obtained green sheet in the barrier rib is dried at the temperature of 300~350° C. for 15~20 minutes to remove an organic solvent and is sintered at the temperature of 750~800° C., thereby forming the barrier ribs.
The green sheet as a material for the barrier ribs is made in a manner that an organic solvent (vehicle) is mixed with a parents glass powder to fabricate a slurry, which is then configured on the sheet by using a tape casting device. A composition ratio of the parents glass powder as the principle material of the green sheet is as shown in the below Table 1.
TABLE 1
Composition
SiO
2
ZnO
B
2
O
3
MgO
Wt %
20~30
20~40
15~25
20~30
Characteristics of the barrier ribs of the conventional art having above composition ratio are as shown in the below Table 2.
TABLE 2
Coefficient of
Sintering
Dielectric
thermal expansion
Withstand
temperature
constant
(10
−7
/° C.)
voltage (kV)
750~850
6~9
75~85
>1.5
That is, the material of the barrier ribs that is generally used in the conventional art has a drawback in that since it has a high content of a substance of which sintering temperature is high, such as SiO
2
, B
2
O
3
or MgO, so that its sintering temperature is high. High sintering temperature causes a deformation to a thin metal substrate, the rear substrate of the plasma display panel during sintering.
Therefore, a material for the barrier ribs that would have a low dielectric constant, a low coefficient of thermal expansion, a high withstand voltage and a low sintering temperature is required.
SUMMARY OF THE INVENTION
Therefore, an object of the present invention is to provide a composition of a dielectric for a plasma display panel in use for fabricating a barrier rib having a low sintering temperature, a low coefficient of thermal expansion, a low dielectric constant and a high withstand voltage.
To achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, there is provided a composition of a dielectric for a plasma display panel comprising a parents glass powder containing 20~40 wt % of ZnO, 15~30 wt % of SiO
2
, 10~20 wt % of B
2
O
3
, 0~30 wt % of PbO, 0~20 wt % of MgO, 1~10 wt % of CaO, 1~10 wt % of Al
2
O
3
, 0~10 wt % of K
2
O, 0~8 wt % of Na
2
O, 0~5 wt % of Li
2
O, 0~2 wt % of Sb
2
O
3
, and 0~2 wt % of As
2
O
3
.
In order to achieve the above object, in the composition of a dielectric for a plasma display panel, the sum of the ingredients of PbO, MgO and CaO is less than 40 wt %.
In order to achieve the above object, in the composition of a dielectric for a plasma display panel, the sum of the ingredients of Li
2
O, K
2
O and Na
2
O is less than 10 wt %.
In order to achieve the above object, the composition of a dielectric for a plasma display panel comprises of a mixture of a parents glass powder and an oxide filler in a predetermined ratio.
In order to achieve the above object, the oxide filler in the composition of a dielectric for a plasma display panel refers to at least one of Mg
2
Al
4
Si
5
O
18
, 2MgOSiO
2
, Zn
2
SiO
4
, PbTiO
2
, quartz, Al
2
O
3
, TiO
2
, ZrO
2
, MgOAl
2
O
3
, 3Al
2
O
3
(2SiO
2
), MgTiO
3
, Zn2SiO
4
, LiAl (SiO
4
) and BPO
4
.
In order to achieve the above object, in the composition of a dielectric for a plasma display panel, 5~50% of oxide filler is mixed with 100% of parents glass powder.
In order to achieve the above object, the composition of a dielectric for a plasma display panel is used for a dielectric thick film to be formed on a rear substrate or on barrier ribs.
REFERENCES:
patent: 4578619 (1986-03-01), Braude
patent: 5674634 (1997-10-01), Wang et al.
patent: 5725919 (1998-03-01), Roberts et al.
patent: 6184163 (2001-02-01), Lee et al.
patent: 6271161 (2001-08-01), Ryu et al.
patent: 6287995 (2001-09-01), Lee
patent: 2001/0051585 (2001-12-01), Ryu et al.
patent: 53-82825 (1978-07-01), None
patent: 2000-095542 (2000-04-01), None
Copy of Japanese Communication.
Bell Mark L.
Bolden Elizabeth A
Fleshner & Kim LLP
LG Electronics Inc.
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