Pursuant to 35 U.S.C. § 119(a), this application claims the benefit of earlier filing date and right of priority to the Korean Application No. 2001-17475, filed on Apr. 2, 2001, the content of which is hereby incorporated by reference herein in its entirety.
1. Field of the Invention
The present invention relates to a method of fabricating a lower substrate of a Plasma Display Panel (PDP) and particularly, to a method of fabricating a lower substrate of a plasma display panel capable of easily forming a separating wall of a high aspect ratio and preventing formation of air layer between a green sheet and substrate and generation of cracks between separating walls.
2. Description of the Background Art
Generally, a PDP is a flat panel display device for displaying images such as letters or graphics by emitting a fluorescent substance by 147 nm of ultraviolet ray generated in discharging He+Xe or Ne+Xe gas. Such PDP can be easily made as a thin film and large screen and accordingly, recently, technology for improving the picture quality is rapidly developed.
The dielectric layer 12 and passivation layer 10 are formed in order on the upper glass substrate. The dielectric layer 12 stores wall charge in plasma discharging and the passivation layer 10 protects the couple of electrodes 4 and dielectric layer 12 against sputtering of gas in plasma discharging and increase emitting efficiency of a secondary battery. Mixed gas of He+Xe or Ne+Xe is injected and sealed to each discharging cell.
The separating wall 8 for preventing electric and optical crosstalk among discharging cells is the most important factor for determining displaying quality and emitting efficiency of the PDP and accordingly, as the panel of the PDP becomes larger and highly finer, much study about the separating wall is performed. Conventionally, there are several applied methods for fabricating the separating wall, such as screen printing method, sand blasting method, additive method, photo-sensitive paste method, Low Temperature Cofired Ceramic on Metal (LTCCM) method and the like.
The screen printing method has an advantage that the process is simple and the cost is low. However, the screen and glass substrate 14 must be arrayed at every printing time and printing and drying of a glass paste must be repeated several times. Also, in case the screen and the glass substrate is wrongly arrayed, since the separating wall transforms, precision of the separating wall is lowered.
The sand blasting method has an advantage that the separating wall can be formed on a large substrate. However, since much amount of glass paste is removed by grinder (namely, grains of sand) in the sand blasting method, material is wasted, thus to increase the fabrication cost. Moreover, the method has a disadvantage that the glass substrate 14 can be cracked or damaged by the impact occurred by the grinder.
The additive method is also appropriate to form a separating wall on the large substrate, but there occurs a problem that the separating wall is broken (damaged) when the residual substance is generated or the separating wall is generated since the photo-resist and the glass paste are not easily separated.
In the photo-sensitive paste method, the used photo-sensitive paste costs much and it is difficult to expose the lower portion of the photo-sensitive paste.
Compared with the above described methods, since the LTCCM method is simple and fabrication of the separating wall with high precision and high ratio, recently, the method is most widely used.
As shown in
In case the material of the substrate 32 is metal, it is desirable that fine glass powder is injected on the substrate 32 in the dry process or wet process before combining the substrate 32 and green sheet 30 so that the combination between the metal surface and green sheet 30 is easy. The injected fine powder is heated at the temperature of about 500 to 600° C. and fused and attached. The green sheet 30 is combined by laminating on the fused and attached metal substrate 32 on which the glass powder is fused and attached.
Then, as shown in
As shown in
Under the condition that the fluidity of the green sheet 30 is increased, after arraying metallic pattern 38 where a groove 38a is formed as shown in
Then, as shown in
After plasticizing the separating wall, reflecting material such as TiO2 is printed on the electrode passivation layer 36 and plasticized before printing the fluorescent substance 6.
As described above, with the LTCCM method, the process can be simple and separating wall can be formed in high precision. However, in the LTCCM method, formation of the separating wall 8 in the high aspect rate having larger height than the width is difficult and the green sheet 30 protruded in the shape of the separating wall is torn in separating the metallic pattern 38 and green sheet 30 or an air layer is generated between the substrate 32 and the green sheet 30 in forming by pressurizing. Such problem is caused by organic material contained in the green sheet 30. In case the amount of organic material in the green sheet 30 is large, the fluidity of the green sheet 30 is improved, but the height of the shaped separating wall is lowered again when the organic material is burnt out in plasticizing the green sheet 30 and the electrode passivation layer 36 after moving the organic material having higher fluidity into the groove 38a of the metallic pattern in forming the separating wall. Also, the portion protruded into the shaped separating wall 8 (upper portion of the separating wall) is torn in separating the metallic pattern 38 and green sheet 30.
On the other hand, since the fluidity of the green sheet 30 is low in case the amount of the contained organic material in the green sheet 30 is small, movement of the green sheet 30 into the groove of the metallic pattern 38a is difficult and accordingly, the separating wall can not be formed.
Also, with the conventional method of fabricating the separating wall using the LTCCM method, the air layer 40 is generated between the green sheet 32 and substrate 30 by difference of frictional force in shaping the wall as shown in
Therefore, the present invention provides a method of fabricating a lower substrate of a Plasma Display Panel (PDP) capable of easily forming a separating wall of a high aspect rate and preventing generation of air layer between a green sheet and substrate in forming a separating wall and cracks on the green sheet between adjacent separating walls.
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 method of fabricating a lower substrate of a plasma display panel, including the steps of preparing a secondary green sheet having larger amount than a first green sheet containing organic material, combining the first and second green sheets on the metal substrate by laminating the sheets, forming an electrode on the second green sheet, forming an electrode passivation layer on the second green sheet and shaping a separating wall by pressurizing the first and second green sheets to be metallic pattern having a groove.
The first green sheet can be solidly combined with a metal substrate since relatively small organic material is contained and the second green sheet can be easily moved by a small pressure in forming the separating wall since large amount of organic material is contained in the second green sheet.
About 5 to 15% of organic material and 85 to 95% of glass powder are mixed on the first green sheet and 15 to 30% of organic material and 70 to 85% of glass powder are mixed on the second green sheet. The organic material includes butylbenzylpthalate and polyvinylbutiral (PVB) and can include ethanol, methylethylketone and fish oil.
The foregoing and other, features, aspects and advantages of the present invention will become more apparent from the following detailed description when taken in conjunction with the accompanying drawings.
The accompanying drawings, which are included to provide a further understanding of the invention and are incorporated in and constitute a part of this specification, illustrate embodiments of the invention and together with the description serve to explain the principles of the invention.
In the drawings:
Reference will now be made in detail to the preferred embodiments of the present invention, examples of which are illustrated in the accompanying drawings.
As described above, the first green sheet 60A and the second green sheet 60B function differently because the sheets contain organic material in different amounts. The first green sheet 60A contains about 5 to 15% of organic material and 85 to 95% of glass powder, the organic materials including butylbenzylpthalate and polyvinylbutiral (PVB). The second green sheet contains more organic material than the first green sheet, for instance, about 15 to 30% of organic material and 70 to 85% of glass powder. Also, the organic material in the first green sheet 60A and the second green sheet 60B can include ethanol, methylethylketone (MEK), fish oil and the like.
The first green sheet 60A and second green sheet 60B is fabricated by forming a first slurry and second slurry containing the above described organic material, shaping in a sheet form by the doctor blading process under the condition that the first slurry and the second slurry are positioned on a polyester film and drying the resultant material.
Then, as shown in
Then, as shown in
As shown in
As described above, the metallic pattern 68 having a groove 68a for forming the separating wall is arrayed on the substrate 62 to which the first green sheet 60A and second green sheet 60B are attached as shown in
As the substrate 62 is pressurized by the metallic pattern, the separating wall 8 is formed by moving the second green sheet 60B and the electrode passivation layer 66 into the groove 68a in the metallic pattern. At this time, the first green sheet moves into the groove 68a having lower but almost same fluidity as that of the second green sheet 60B due to having smaller amount of organic material than the second green sheet 60B.
Then, as shown in
According to the method of fabricating the lower substrate of the PDP in accordance with the present invention, the friction between the first green sheet 60A and the second green sheet 60B in forming the separating wall is smaller and the friction between the first green sheet 60A and the substrate 62 in forming the separating wall also is smaller. Furthermore, the second green sheet 68B can move into the groove in the metallic pattern 68 with less pressure due to the smaller amount of organic material contained in the second green sheet 68B in forming the separating wall. Therefore, forming the separating wall 8 at a high rate is possible and generation of air layer between the first green sheet 60A and the second green sheet 60B or between the substrate 62 and the first green sheet 60A is prevented. Furthermore, as shown in
As described above, in the method of fabricating the lower substrate of the PDP in accordance with the present invention, the separating wall composed of the second green sheet is formed by connecting the first green sheet containing less organic material on the substrate and laminating the second green sheet having more organic material on the substrate. Therefore, with a relatively small pressure applied to the metallic pattern, the separating wall can be formed at a high rate by the second green sheet having higher fluidity. Furthermore, since the friction between the first green sheet and the second green sheet and between the first green sheet and the substrate is small, generation of air layer between the first green sheet and the second green sheet or between the substrate and the first green sheet can be prevented and generation of a crack on the green sheets among the adjacent separating walls can be prevented.
As the present invention may be embodied in several forms without departing from the spirit or essential characteristics thereof, it should also be understood that the above-described embodiments are not limited by any of the details of the foregoing description, unless otherwise specified, but rather should be construed broadly within its spirit and scope as defined in the appended claims, and therefore all changes and modifications that fall within the metes and bounds of the claims, or equivalence of such metes and bounds are therefore intended to be embraced by the appended claims.
Number | Date | Country | Kind |
---|---|---|---|
2001-17475 | Apr 2001 | KR | national |
Number | Name | Date | Kind |
---|---|---|---|
5747931 | Riddle et al. | May 1998 | A |
5866240 | Prabhu et al. | Feb 1999 | A |
6140759 | Sreeram et al. | Oct 2000 | A |
6149482 | Sakasegawa et al. | Nov 2000 | A |
Number | Date | Country |
---|---|---|
11219659 | Aug 1999 | JP |
11288662 | Oct 1999 | JP |
2000-067760 | Mar 2000 | JP |
2000067760 | Mar 2000 | JP |
P2000-127630 | May 2000 | JP |
Number | Date | Country | |
---|---|---|---|
20020168914 A1 | Nov 2002 | US |