JP2001216891A - Method of forming rib for plasma display panel - Google Patents

Abstract

PROBLEM TO BE SOLVED: To exert a superior sand blasting performance and enable recycling of the grinding powder. SOLUTION: In this method of forming a rib 3 of a plasma display panel by a sand blasting method, superior sand blasting performance can be achieved by using inorganic powders, having a prescribed distribution of particle size and a predetermined hardness as the grinding material, and as the grinding material and a ground rib forming material in the grinding powder can be separated from each other by a classification process, the sand blast waste can be recycled, and environmental problems due to the disposing of the sand blast waste can be also avoided.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a process for manufacturing a plasma display panel (hereinafter referred to as "PDP"), and more particularly to a technical field of forming a rib constituting a discharge space of a PDP by a sandblasting method. .

[0002]

2. Description of the Related Art In general, a PDP has a structure in which a pair of electrodes arranged regularly on two opposing glass substrates are provided, and a gas mainly composed of Ne, Xe or the like is sealed between the electrodes. Then, a voltage is applied between these electrodes,
By generating a discharge in a minute cell around the electrode, each cell emits light to perform display. In order to display information, regularly arranged cells are selectively caused to emit light. There are two types of PDPs, a direct current type (DC type) in which the electrodes are exposed to the discharge space, and an alternating current type (AC type) in which the electrodes are covered with an insulating layer. And a refresh driving method and a memory driving method.

FIG. 1 shows a configuration example of an AC type PDP. This figure shows the front plate and the back plate separated from each other. As shown in the figure, two glass substrates 1 and 2 are arranged in parallel and opposed to each other, and both become the back plate. The ribs 3 provided on the glass substrate 2 in parallel with each other are held at regular intervals. On the back side of the glass substrate 1 serving as a front plate, composite electrodes composed of a sustain electrode 4 which is a transparent electrode and a bus electrode 5 which is a metal electrode are formed in parallel with each other, and a dielectric layer 6 is covered thereover. The protective layer 7 (MgO layer) is further formed thereon. On the front side of the glass substrate 2 serving as the back plate, address electrodes 8 are formed between the ribs 3 so as to be orthogonal to the composite electrodes and are formed in parallel with each other. Are formed, and a phosphor layer 10 is provided so as to cover the wall surface of the rib 3 and the cell bottom surface. This AC type PDP is of a surface discharge type, and has a structure in which an AC voltage is applied between composite electrodes on the front panel to discharge. Then, the phosphor layer 10 emits light by the ultraviolet light generated by the discharge, so that an observer can visually recognize the light transmitted through the front plate.

Conventionally, the ribs on the back plate of such a PDP have been formed by overprinting by screen printing. However, recently, the ribs are often formed by a so-called sand blast method from the viewpoint of accuracy. When ribs are formed by this sandblasting method, a low-melting point glass powder, an inorganic powder such as a refractory filler is used as a main component or a component, and a rib paste obtained by adding an appropriate binder resin and a solvent to the substrate is applied to a substrate. After forming a rib forming material layer by drying and providing a photosensitive resin composition layer having sandblast resistance thereon, patterning is performed on a cell defining mask by a photolithography method, and through the mask A procedure of performing sand blasting, removing the mask, and firing is adopted. However, glass beads, SiC, S
Inorganic powders such as iO ₂ , Al ₂ O ₃ and ZrO ₂ are used.

[0005]

By the way, recently, P
There is an increasing demand for DPs to be larger, have higher definition, have higher brightness, and have a longer life. In order to meet these demands, low-melting glass ribs are formed on a substrate such as glass by sand blasting to reduce the rib width and increase the uniformity and increase the phosphor application area. Development is underway. Incidentally, such a PDP has, for example, a rib width of about 50 μm, a rib height of 100 to 150 μm, and a gap between the ribs of 100 μm.
It is about μm.

In the sand blasting method, patterning is performed by shaving off and removing unnecessary portions of a rib forming layer with a grinding material sprayed from a nozzle. However, if there are coarse particles in the inorganic powder used for the grinding material. As a result, defects such as rib breaks and cuts increase, and high quality ribs cannot be formed, which adversely affects PDP performance. Also, if the hardness of the abrasive used is small, the crushing of the abrasive itself proceeds, so that the life is shortened. Conversely, if the hardness is too high, damage to the blasting device increases.

[0007] Further, when the above-mentioned abrasive material of the inorganic fine powder is used, a large amount of the abrasive material mixed with the shavings of the rib material is generated, and it is difficult to separate and reuse the two. However, this has to be disposed of as waste material, but this is a major environmental and cost problem.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-mentioned circumstances, and an object of the present invention is to provide a PDP rib which exhibits good sand blast performance and enables reuse of waste sand blast. It is to provide a forming method.

[0009]

In order to achieve the above object, the present invention provides a method for forming a rib forming material layer on a substrate, forming a mask for sand blasting in a pattern thereon, and then forming the mask on the mask. After removing unnecessary portions of the rib-forming material layer by spraying abrasive from above, and then removing the sandblast-resistant mask and forming a rib of a desired pattern through a firing step. As a grinding material for the rib forming material layer, the Vickers hardness is 1000 to 2500, and the cumulative% diameter is D ₅₀ = 10 to 15 μm in the volume-based particle size distribution.
m, an inorganic powder having a distribution of D ₉₀ <30 μm and D ₁₀ > 4 μm. Here, the cumulative 10% diameter D ₁₀ > 4 μm means that the diameter corresponding to 10% of the volume accumulation is 4%.
μm, and the cumulative 50% diameter D ₅₀ =
10 to 15 μm means that the diameter corresponding to 50% of the volume accumulation is 10 to 15 μm, and the cumulative% 90 diameter D ₉₀ <
30 μm means that the diameter corresponding to 90% of the volume accumulation is 30 μm.
m.

[0010]

DESCRIPTION OF THE PREFERRED EMBODIMENTS It is important that the sandblasted abrasive used in the present invention is a classified powder having a predetermined particle size distribution together with the material constituting the sandblasted abrasive. It is preferably adjusted by means. In order to cope with the enlargement, high definition, high brightness, and long life of the PDP, it is important to manufacture the ribs without any defects or to prevent the occurrence of defective reserves.
When the particle size of the abrasive is less than 4 μm, the grinding ability is too small, and when the particle size exceeds 30 μm, the rib pattern is broken or the abrasive pierces the rib, and the rib defect or the defect reserve The occurrence becomes remarkable, and it becomes difficult to form high-quality ribs. Also, it is difficult to classify the abrasive having a particle size of less than 4 μm from the ground rib.

The Vickers hardness of the abrasive is 1000
If it is less than 2, the probability that the abrasive itself is broken by the impact during sandblasting increases, and conversely, the Vickers hardness becomes 25.
If it exceeds 00, although there is no problem in the grinding force, the components of the blasting device are cut off, leading to an increase in the maintenance cost.

When the ground rib material is reused, it is important to separate the ground material and the rib material in the grinding powder. In this case, there is a situation that it is desired to prevent the abrasive material from being mixed into the rib material as much as possible. However, when the grinding material is crushed, the size becomes close to the particle size of the shavings of the rib material, and separation from the rib material becomes difficult. Furthermore, when the degree of mixing increases, it becomes difficult to adjust the composition of the inorganic component. Above all,
If the abrasive component is not originally contained in the rib material,
I want to avoid contamination as much as possible. For this purpose, the abrasive itself should be hard to be crushed, and should not be easily mixed into the rib material at the time of classification. Incidentally, the average particle size of the abrasive is 10 to 15 μm, and the average particle size of the inorganic powder constituting the rib material is 1 to 2 μm.

As the inorganic powder used for the sandblasting abrasive, any kind of inorganic powder can be used as long as the above conditions are satisfied. In particular, Al ₂ O ₃ (alumina) and ZrO ₂ (zirconia) are used. It is suitable.

The raw material components of the above sandblasted abrasive are:
Usually, the particle size distribution is obtained in a wide state, but a powder having a substantially uniform particle size is obtained, and the powder having a particle size distribution described above is subjected to a dry classifier.
Specifically, it is preferable to cut the coarse powder and the fine powder using a dry classifier (for example, “Toroplex” manufactured by Hosokawa Micron) in order to make the particle size uniform. Also,
Although there is a method of pulverizing and classifying to obtain a powder that accurately maintains the maximum particle powder, it is not preferable because the pulverization lowers the plasticity of the material powder.

Using the sandblasted abrasive of the present invention, P
An ordinary method is employed to form the DP ribs. First, a rib forming material layer is formed by applying and drying a rib forming paste on a substrate, and a photosensitive resin composition layer having sandblast resistance is provided thereon, and then activated through a photomask. By selectively irradiating a light beam and subsequently developing, a sand blast mask pattern is formed, and the exposed portion of the rib forming material layer is ground with the above sand blast abrasive. In this case, the injection pressure is preferably 1.0 to 3.0 as in the case of the ordinary sandblast method.
Sandblasting is performed by injecting at a rate of 5 kg / cm ^{2 to} 100 g / min.

The rib-forming paste for forming the rib-forming material layer has a composition in which an inorganic powder such as a low-melting glass powder and a refractory filler is a main component or a component, and an appropriate binder resin and a solvent are added thereto. Paste. In order to produce this paste, first, an inorganic powder mixed with a low-melting glass powder, a refractory filler, a pigment and the like is pulverized by a ball mill to adjust the particle size thereof. Next, the crushed inorganic powder is sieved to remove large-sized ones, and dried to complete a frit, and a binder resin and a solvent are added to the frit to form an ink, thereby obtaining a paste. Then, as described above, the rib forming paste is applied to the substrate and dried to form a rib forming material layer, and a sand blast mask is formed thereon, and then the abrasive is sprayed from the spray nozzle. Spray and perform sandblasting.

The grinding powder generated during sandblasting is collected and classified into a coarse powder side and a fine powder side by a cyclone attached to the blasting device. Since the coarse powder side is an abrasive, it is reused as it is. On the other hand, the fine powder side is composed of some abrasives, crushed abrasives, and fragments of the rib-forming material ground from the substrate. Separated from the ground rib forming material. Some of these abrasives are reused as abrasives. Since the crushed abrasive and the rib material contain the crushed abrasive, the composition is adjusted and the crushed abrasive and the rib material are reused for producing a repaste.

When preparing the re-paste, since the resin is already mixed in the recovered rib material on the fine powder side, it is necessary to adjust not only the frit composition but also the resin amount in the composition adjustment. Therefore, the method of preparing the repaste is different from a new one, and after mixing the vehicle with the insufficient component and the corresponding diluent solvent into the resin-mixed frit to form a paste,
A new paste is mixed at a predetermined ratio.

[0019]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail below with reference to a series of steps for forming high-definition ribs on a PDP substrate.

(Step of Forming Electrode Layer) The planar size is 1
A glass substrate having a size of 000 × 600 mm and a thickness of 2.8 mm is prepared, and a large number of parallel striped electrodes are formed on one surface of the glass substrate at an interval of 150 μm by screen printing.

(Step of forming rib-forming material layer) A low-melting-point glass paste using a cellulose-based resin or an acrylic-based resin as a binder is collectively coated on the entire surface of the glass substrate on the electrode side by a die coater. Dry for a minute and solidify to form a rib-forming material layer. Since the low-melting-point glass layer is formed from a low-melting-point glass paste using a cellulose-based resin or an acrylic-based resin as a binder, the grinding property by blasting (hereinafter referred to as blasting property) is extremely good.

(Step of forming a mask for sandblasting) A dry film ("Audil BF603" manufactured by Tokyo Ohka Kogyo Co., Ltd.) is laminated on the entire surface of the rib forming material layer.
Exposure and subsequent development are performed to form a patterned resist layer on the rib forming material layer as a sandblast mask. As the developing solution, a 0.2% aqueous solution of sodium carbonate is used. The pattern of the resist layer of this embodiment has a width of 5
The electrodes on the surface of the glass substrate have a distance of 1 μm between the resist layers.
It is arranged so as to be located substantially at the center between 00 μm.

(Sand blasting process) The substrate is transported on a number of transport rollers and is loaded into the blasting chamber. Then, a sandblast abrasive is sprayed from a spray nozzle toward the rib forming material layer and the resist layer side of the workpiece having the rib forming material layer and the resist layer formed on the surface of the substrate, that is, the glass substrate. Eight injection nozzles are provided that are capable of reciprocating in a direction perpendicular to the direction of transport of the workpiece. Each injection nozzle is 150mm ×
A slit nozzle that injects the abrasive almost vertically from a 0.5 mm slit is employed, and this slit nozzle itself has a wider spray distribution than a conventional round nozzle (10 mmφ). In order to further improve the processing uniformity, the nozzle driving speed is increased.

In the processing chamber, an abrasive is sprayed together with the compressed air onto the side of the glass substrate on the side of the resist layer and the rib forming material layer, so that the rib forming material layer other than the rib forming material layer immediately below the resist layer is removed. A rib is formed by grinding and removing. The rib thus formed has a width of 50 μm and a height of 1 μm.
The distance between the ribs is 50 μm, and the distance between the ribs is 100 μm. Specifically, when a sandblast abrasive is injected from the injection nozzle to the resist layer and the rib-forming material layer side of the substrate in the blasting chamber, the rib-forming material layer immediately below the resist layer is protected by the resist, so the abrasive material is used. Although not ground or engraved, all portions of the rib forming material layer other than the rib forming material layer immediately below the resist layer are ground and removed.

(Firing Step) The workpiece on which the ribs are formed on the surface of the glass substrate is gradually heated to a temperature at which the low-melting glass lead glass is completely melted and the binder is incinerated, thereby forming the ribs. The low melting glass and the binder of the resist are completely burned, and the low melting glass is melted and fired to form ribs.

The ribs are formed by the above steps. In the present embodiment, a test was conducted by performing the above sandblasting using various inorganic powders as abrasives. The particle size distribution meter used in the present invention is "Microtrack FRA" manufactured by Nikkiso Co., Ltd.

First, as a first test, sandblasting was performed on the above-described substrate using various inorganic powders having the same average particle size but different hardness as the abrasive, and the life of the abrasive itself and the blasting device were determined. The damage was evaluated. The results are as shown in Table 1. As can be seen from Table 1, if the Vickers hardness of the abrasive is less than 1000, the life of the abrasive itself is shortened, and if it exceeds 2500, the blast device is damaged.

[0028]

[Table 1]

In a second test, the same type of alumina
(WA series manufactured by Fujimi Incorporated)
However, using a material having a different cumulative 50% diameter as the abrasive
Sandblasting of the substrate of
The rib defect was evaluated. The results are shown in Table 2.
It is. As can be seen from Table 2, the cumulative 50% diameter D ₅₀
Is less than 10 μm, the grinding speed becomes
After that, rib defects came to be seen.

[0030]

[Table 2]

As a third test, alumina (WA series manufactured by Fujimi Incorporated) having the same cumulative 50% diameter D ₅₀ (10 to 15 μm) but different particle size distributions
Using sand as a grinding material, sand blasting the above substrate and classifying it with rib defects (grinding material mixing on the fine powder side)
Was evaluated. Table 3 shows the results.
As can be seen from Table 3, the cumulative 90% diameter D ₉₀ <30 μ
Alumina having a distribution of m and a cumulative 10% diameter D ₁₀ > 4 μm could be sandblasted without generating rib defects, and classification by a cyclone attached to the blasting device could be performed well.

[0032]

[Table 3]

[0033]

As described above, according to the method for forming a rib of a PDP of the present invention, when forming a rib pattern by a sandblast method, an inorganic powder having a predetermined hardness and a predetermined particle size distribution is ground. By using it as a material, good sandblasting performance is exhibited, and the grinding material and the ground rib-forming material can be separated from the grinding powder by a classification process. Environmental problems due to waste material disposal can also be avoided.

[Brief description of the drawings]

FIG. 1 is a perspective view showing an example of a plasma display panel in which a front plate and a back plate are separated from each other.

[Explanation of symbols]

 1, 2 glass substrate 3 rib 4 sustain electrode 5 bus electrode 6 dielectric tank 7 protection tank 8 address electrode 9 dielectric tank 10 phosphor layer

Claims (1)

[Claims] 1. A rib forming material layer is formed on a substrate, and a sand blast resistant mask is formed thereon in a pattern. Then, an abrasive is sprayed from above the mask to remove unnecessary portions of the rib forming material layer. Is removed, and then a mask for sand blast resistance is removed, and a rib forming method of a plasma display panel comprising a step of forming a rib having a desired pattern through a firing step is performed. ２2,500, and further, in the volume-based particle size distribution, the cumulative% diameters are D ₅₀ = 10 to 15 μm, D ₉₀ <30 μm, D ₁₀ > 4 μm, respectively.
A method of forming a rib for a plasma display panel, comprising using an inorganic powder having a distribution of: