KR100430590B1 - Manufacturing method of barrier ribs for plasma display panel by sandblasting thick films with different etching rate - Google Patents

Abstract

The present invention is to manufacture a partition formed on the back plate of the AC plasma display device using a sandblasting method, to shorten the thick film and the protective film manufacturing process to excellent productivity and production yield of the partition wall manufacturing method and composition for thick film formation thereof. It is about. According to the method provided by the present invention, since it is possible to simplify the manufacturing process by eliminating the exposure step in the partition fabrication process, the productivity of the manufacturing process is very high, which has the advantage of reducing the manufacturing cost of the plasma display back panel. have.

Description

Manufacturing method of barrier ribs for plasma display panel using thick film having different sandblasting etching rate {sanduishing thick films with different etching rate}

The present invention relates to a method of manufacturing a back plate-shaped partition wall for a plasma display panel (PDP), and more particularly, to manufacture a partition wall using a thick film for partition walls and a protective film having different sandblasting speeds. Adjusting sandblasting properties by appropriate pre-firing of a thick film containing powder and ceramic powder with a certain amount of a solvent, a dispersant, a binder, and a plasticizer, and a protective film having a different sandblasting etching rate on the thick film. Forming by a printing method, etching the thick film into a partition shape by sand blasting, firing the formed partition wall, and the like.

Plasma display display devices are flat display devices, and are mainly used as large display devices of 40 inches or more because of their excellent image quality, thin thickness, and light weight. In the plasma display display device, a pixel is formed at a point where the barrier rib formed on the rear plate, the address electrode, and the surface discharge electrode formed on the front plate vertically intersect to form an image. The structure of the plasma display display device is schematically illustrated in FIG. 1. When a voltage is applied between the sustain electrode 4 of the front plate 1 and the address electrode 5 of the back plate 8, plasma is formed in the space formed between the partition walls 6 and is generated between the surface discharge sustain electrodes. The vacuum ultra violet is excited from the plasma to excite the partition 6 and the phosphor 7 coated on the bottom surface between the partition walls to generate red, green and blue visible light.

The partition wall defines a pixel in the plasma display display element, thereby preventing mixing of the pixels and providing a space in which the phosphor can be applied, thereby increasing the luminous efficiency of the display element. Sand blasting (sand blasting) method is mainly used as a method of forming such a partition. This process is schematically shown in FIG. This method is described in detail in Japanese Patent Application No. 11-120905, Korean Patent Application No. 2000-10322, and the like. The paste containing the glass powder for the partition material and the ceramic filler is coated on a back plate substrate such as a glass plate. After repeating the application and drying 6 to 7 times to form a thickness of about 200㎛, by coating a dry photoresist (DFR) with excellent etching resistance to sandblasting on the dried thick film, The remaining portion except for the portion where the partition wall is to be formed is removed through the exposure and development processes. Then, a ceramic powder, such as calcium carbonate (CaCO ₃ ), is sprayed with the pressurized air to etch the portion where the photoresist is removed to form a partition.

This method is mainly used to manufacture a partition for a conventional plasma display display device because the process is relatively stable, but has the following disadvantages.

First, in order to form a thick film having a predetermined thickness using a paste, the printing and drying processes should be repeated six or more times, and the productivity of this process is very low. Therefore, there is a problem that a lot of investment in production equipment is required to satisfy the required production.

Second, in the case of forming the thick film for the partition wall by the paste multilayer printing method, the sandblasting characteristics of each layer of the printed thick film are different so that the lateral shape of the partition wall becomes uneven, which causes the unevenness of the pixel brightness of the plasma display device. do. That is, the first printed thick film layer experiences at least six repeated drying cycles (when printing seven layers), while the last printed thick film layer experiences only one drying cycle. Accordingly, each layer formed by the multilayer printing method has a different sandblasting etching rate, which causes non-uniformity of the etching surface. If the side of the etched barrier is nonuniform, it affects the area and thickness of the phosphor to be applied, which ultimately affects the brightness of the pixel. Therefore, a method of forming a thick film having a uniform etching rate is essential.

Third, improvement in the process of forming the sandblasting protective film is required. In order to form the barrier rib by etching the thick film by sandblasting, a protective film must be formed. As described above, the DFR must be laminated on the barrier thick film and subjected to exposure, development, and drying. This method requires expensive large-area exposure and development equipment, and has a problem of lowering the yield of products due to the high possibility of defects during the protective film forming process and the DFR removal process after sandblasting. therefore. It is necessary to improve this protective film forming process.

Accordingly, an object of the present invention is to solve the problems of the prior art as described above and solve the technical problems that have been desired from the past.

Looking specifically at this,

Firstly, the thick film for sandblasting etching process is replaced by the printing method to provide a highly productive thick film forming process;

Secondly, sandblasting provides a composition of a dry film having a uniform shape on the side wall of the barrier rib during etching;

Third, instead of the exposure and development process, which is an expensive protective film formation process during sandblasting, a manufacturing process capable of manufacturing the partition wall of the plasma display panel with economical and high quality by using a low cost equipment and a high productivity process and its use It is an object to provide a dry film.

1 is a cross-sectional perspective view schematically showing the structure of a plasma display panel;

2 is a process diagram schematically showing a process of manufacturing a partition by a conventional sandblasting method;

3 is a process diagram schematically showing a part of a partition fabrication process according to an embodiment of the present invention;

4A is a graph schematically showing a sandblasting etch rate according to a preliminary firing temperature, and FIG. 4B is a graph schematically showing a sandblasting etch rate according to a preliminary firing time;

5 is a graph of the effect of sandblasting etch angle on the etch rate of sandblasting;

6 is a schematic diagram showing an etching angle defined in the present invention.

Explanation of symbols for the main parts of the drawings

1: top plate 2: top plate dielectric

3: MgO protective layer 4: Sustain electrode

5 address electrode 6 partition wall

7: phosphor 8: back panel

9: backplane dielectric layer

The partition wall manufacturing method of the present invention for achieving the above object, in forming the partition wall on the back plate of the AC plasma display device,

(A) mixing a glass and ceramic mixed powder, an organic binder, a dispersant and the like into a solvent to produce a slurry for thick film production;

(B) using the slurry to form a thick film on a glass substrate on which a back plate dielectric and an electrode are printed, and prefiring it to a predetermined temperature profile to form a dry film;

(C) printing the paste containing the partition material as a protective film on the dry film in a pattern of the partition by the screen printing method and then drying the paste;

(D) mechanically etching the thick film thus obtained by sandblasting to form partition moldings; And,

(E) baking the resulting partition molding to form a partition.

As described above, one of the most important features of the present invention is that the thick film for fabricating the barrier ribs is manufactured in a single process, and that there is no need to remove the protective film component used in the etching process later. Therefore, the thick film formation and drying in step (B) need not be repeated two or more times, and there is no need to go through the process of removing the protective film after step (D) or afterwards.

In step (A), the composition of the slurry for thick film production is

(a) 100 parts by weight of a powder mixture of 50:50 to 95: 5 (volume ratio) of the glass powder and the ceramic powder;

(b) 20 to 40 parts by weight of the solvent;

(c) 2 to 8 parts by weight of the organic binder;

(d) 0.5 to 3 parts by weight of dispersant;

(e) 0 to 12 parts by weight of a plasticizer;

(f) 1 to 3 parts by weight of other additives.

As the glass powder, PbO-B ₂ O ₃ -SiO _{2 type} , B ₂ O ₃ -SiO ₂ -Bi ₂ O ₃ -P ₂ O _{5 type} , Bi ₂ O ₃ -B ₂ having an average particle size of 0.2 to 10 μm One or two or more mixtures selected from O ₃ -ZnO-BaO-SiO ₂ systems and the like may be used, and as the ceramic powder, alumina (Al ₂ O ₃ ), titanium oxide ( One or more mixtures selected from TiO ₂ ), zirconia (ZrO ₂ ), manganese oxide (MnO), copper oxide (CuO), iron oxide (Fe ₂ O ₃ ), and the like may be used.

The solvent is methyl ethyl ketone, ethyl alcohol, isopropyl alcohol, toluene, toluene, diethyl ether, trichloroethylene, methanol A single solution such as) or a mixed solution of two or more may be used.

The organic binder is cellulose, ethyl cellulose, polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), polyacrylate esters, and the like. One or more mixtures selected may be used and their average molecular weight is 30,000 to 100,000.

The plasticizer is one selected from diethyl oxalate, polyethylene, polyethylene glycol, dimethyl phthalate, dibutyl phthalate, dioctyl phthalate, and the like. Or mixtures of two or more may be used.

The dispersant may include fish oil (menhaden fish oil), polyethyleneimine, glyceryl trioleate, polyacrylic acid, corn oil, glycerine, phosphate ester ( phosphate ester) and the like, or a mixture of two or more may be used.

The other additives include a functional agent having a different functional group (coupling agent), to improve the wetting properties of the powder and the binder during slurry production, and to maintain a stable morphology during mechanical etching. In addition, as such other additives, one or a mixture of two or more selected from triamino silane (3-AminopropylTrimethoxy silane), triethoxy silane (3-Aminopropyltriethoxy silane), amino silane (Amino-silane) and the like may be used.

Details of such a partition composition are disclosed in the applicant's patent application No. 2000-27178, filed May 19, 2000, the contents of which are incorporated herein by reference. Looking at one example of making such a composition as a slurry for a thick film as follows. After the mixed powder, dispersant and other additives are added to the solvent and ball milled for 8 to 10 hours, the organic binder can be mixed into the first milled slurry and ball milled again for 8 to 10 hours to produce a stable slurry. .

In step (B), the method of forming the thick film on the glass substrate may be selected from the following two methods.

(1) The slurry from step (A) may be transferred onto a glass substrate using a doctor blade, tape caster, roll coater, extrusion coating, die casting, cap coating apparatus, or the like. A method of directly forming a thick film in one coating process; And

(2) The slurry from step (A) was formed on a carrier film such as a mylar film by using a doctor blade method, a tape casting method, or the like, and dried. Thereafter, a secondary thick film is formed on the glass substrate by a lamination process.

In some cases, in the method (2), an adhesive layer may be added between the dry film and the glass substrate in order to improve the adhesion with the glass substrate. This adhesive layer is formed by applying a glue between glass substrates using a binder having similar properties to those used in slurry production or a binder used in slurry production. The thickness of the layer is not an important factor in the process, but it is preferable to apply uniformly to 10 μm or less.

In order to adjust the sandblasting etching rate of the formed thick film to an appropriate level, prefiring is performed in step (B). The profile of the prefiring temperature varies from 120 to 300 ° C., preferably in the range of 190 to 280 ° C., depending on the composition of the thick film. If the prefiring temperature is 120 ° C. or less, there is a problem in that a desired etching rate cannot be obtained due to the characteristics of the binder of the thick film. There is a problem, and there is a problem of waste of energy due to high temperature in the process. The prefiring time may vary slightly depending on the temperature, and is approximately 1 hour to 1.5 hours. If the firing temperature is high, the firing time is shortened, and if the firing temperature is low, the firing time is long.

In step (C), a paste is printed on a thick film on the pre-fired glass substrate using a printing machine such as a screen printer to form a protective film pattern. As the paste, a paste including a partition material which is currently used commercially for the production of PDP (for example, manufactured by Okuno, Ashai, Japan) may be used. Generally, a pigment and two or more solvents, a binder, and the like in glass powder are used. It is prepared by mixing additives. The protective film-forming paste serves to protect the thick film under the protective film during the etching process in step (D), and therefore, the protective film-forming paste must have a harder and brittle characteristic than the thick film component when dried. The protective film is formed by printing the paste on the surface of the thick film using a screen on which patterns such as stripe type, honeycomb type, and meander type are formed. The protective film formed is dried to have an appropriate strength and etching rate. The drying conditions vary depending on the composition of the paste, and are carried out for 10 to 30 minutes in a temperature range of approximately 25 to 180 ° C, more preferably 90 to 150 ° C. If the drying temperature is 25 ℃ or less, the solvent used in preparing the paste takes longer than 48 hours to dry, and if the drying time is longer, the binder and other additives in the used paste are removed from the material. Therefore, there is a problem that can not obtain the appropriate strength and etching speed

In step (D), factors affecting the etch rate during sandblasting of the thick film containing ceramic powder and the like, the kind and amount of organic composition such as preliminary firing temperature and time of the dry film, binder, plasticizer, etc. , The shape, size, content and sandblasting etch angle of the glass powder and ceramic powder, and the etch rate is affected by many of these variables.

4a and 4b schematically show the sandblasting etch rate with the preliminary firing temperature and time, according to the study of the inventors, the etching rate increases exponentially as the preliminary firing temperature increases (FIG. 4a). The etching rate was found to increase approximately linearly with reference to the preliminary firing time (see FIG. 4B).

On the other hand, the etching rate of the thick film according to the sandblasting angle is generally very different behavior depending on the mechanical properties of the thick film. FIG. 5 schematically shows the change in the etching rate according to the sandblasting angle of the thick film having two different mechanical properties. Sandblasting angle in this specification, as shown in Figure 6, means the average angle (θ) that the etching medium is sprayed with respect to the horizontal plane of the thick film to the protective film. It is 90 degrees when the spraying direction is perpendicular to the horizontal plane of the thick film or the protective film (lower feature in FIG. 6), and 0 ° when parallel to the horizontal plane (left feature in FIG. 6). In view of the extremely fine size of the bulkhead, the etching medium is almost parallel to each other for the thick film or the protective film corresponding to the size of the partition to be produced, although the etching medium sprayed from the related apparatus during sandblasting is radially sprayed from the ejection outlet. Can be regarded as behaving.

The graph A of FIG. 5 shows the sandblasting characteristics of the strong, brittle thick film. In this material, the maximum etching rate is shown when the sandblasting angle is 90 °. This is because the etching is performed by a mechanism in which the etching medium is cracked by the collision with the thick film during sandblasting. The thick film having such characteristics is generated when the binder organic material is brittle when the preliminary firing temperature is high or the preliminary firing time is long and the organic matter in the thick film is evaporated in a large amount, thereby increasing the pore content.

In comparison, the thick film having a high ductility exhibits a maximum etching rate at a sandblasting angle of about 30 ° as shown in the B graph of FIG. 5. The phenomenon of exhibiting the maximum etching rate at the low etching angle is because the thick film is etched by the grinding mechanism of the grinding medium during sandblasting. In other words, the grinding media collide with the thick film surface at an angle and are etched in such a manner that the soft thick film is scraped off. Thick films having such etching characteristics appear when the preliminary firing temperature is low and the preliminary firing time is short, so that a large amount of organic material remains in the thick film or the organic material contains a relatively large amount of plasticizer and thus has ductility. The angle representing this maximum etching rate decreases to around 0 ° as the ductility increases, and increases to around 90 ° as the brittleness increases.

Therefore, as in the present invention, if two layers (thick film and protective film) having different sandblasting etching characteristics are formed on the glass substrate on which the back plate dielectric and the electrode are formed, separate materials and manufacturing processes such as DFR are not used. It is possible to form a protective film for sandblasting without. That is, it is possible to form a protective film by using a black matrix paste or a general partition paste that is conventionally used.

In the present invention, the slurry used for the thick film is a lot of pores by the volatilization of the organic material is formed during the preliminary firing to form a porous structure, the paste used for the protective film is relatively bonded while the drying process Because I am contained a lot in the material, it forms a relatively dense structure compared to the thick film. Thus, for two structures (protective film, thick film) having such different sandblasting etching characteristics, for example, sandblasting with an etching angle of 35 ° to 45 ° results in a relatively high etching speed at such an etching angle. Since the visible thick film is preferentially etched and the etching of the protective film is very small, as a result, the thick film under the protective film is not etched, so that the partition wall is formed according to the shape of the protective film. In addition, since the protective film can be used as a partition material for the PDP backplane by itself, it does not need to be removed separately.

Therefore, the present invention, in order to control the etching rate of the formed thick film, by performing the pre-baking of the thick film and drying of the protective film in the range of the temperature and time described above, to maximize the difference between the etching rate of the pre-baked thick film and the protective film paste. It involves making. However, since the etching rate may vary depending on the composition of the slurry constituting the thick film, the prebaking temperature and time of the thick film, and the like, the control of the etching angle does not exert the effects of the present invention. Therefore, the present invention also includes maximizing the etching rate of the prebaked thick film and protective film paste by changing the sandblasting angle in the range of 0 to 90 ° when etching by the sandblasting method.

Those skilled in the art to which the present invention pertains will be able to easily recognize it based on the above contents even if not all specific examples for such various conditions.

In Fig. 3, in step (B), the partition wall is formed by the method (1), that is, a method of directly forming a thick film in a single coating process on a glass substrate, by the process of steps (B) to (D). The process of forming the molding is schematically illustrated.

Although specific examples of the present invention will be described with reference to the following examples, the contents of the present invention should not be construed to be limited thereto.

(Example 1)

Methyl ethyl ketone (MEK) as a solvent in 100 parts by weight of a mixed powder of glass powder (PbO-B ₂ O ₃ -SiO ₂ system: average particle size: 1.5 μm) and ceramic powder (average particle size: 2.2 μm) of 70:30 (volume ratio) 30 parts by weight of a mixed solvent of 1: 1 (volume) of toluene and 3 parts by weight of BYK-110 (USA.BYK-Chemie) as a dispersant, and a coupling agent (coupling agent / Tri-methoxy silane) as other additives. After adding 1 part by weight to ball mill for 8 hours, 3 parts by weight of ethylene cellulose (Ethyl cellulose) as an organic binder was mixed into the slurry after the first milling, and then ball milled again for 8 hours to prepare a stable slurry.

The slurry thus prepared was formed on a glass substrate (size: 7.5 inches to 75 inches) on which an electrode and a back plate dielectric layer were formed, using a tape caster, to form a direct thick film at a height of 200 μm, at 280 ° C. for 1 hour 30 minutes. Prebaking during the process. Using a screen printing apparatus on the dry film after preliminary firing process, paste (Japan. Okuno coperation) containing partition material is formed into a partition wall shape with a stripe pattern of about 30 μm thickness, 50 μm width, and 420 μm pitch. The protective film was printed. The substrate on which the paste was printed was dried at 120 ° C. for 20 minutes so as to maximize the etching rate difference with the thick film. Sandblasting was performed on the thick film thus formed using a known sandblasting process at an etching angle of 45 ° to form a partition wall having a height of 155 µm and a thickness of 50 µm. The formed partition was calcined at 560 ° C. for about 1 hour, whereby a partition for plasma display having a height of 123 μm and a thickness of 42 μm was produced by sintering shrinkage.

(Example 2)

MEK / toluene mixed solvent as a solvent in 100 parts by weight of 80:20 (volume ratio) of glass powder (PbO-B ₂ O ₃ -SiO ₂ system: average particle size: 1.5 μm) and alumina powder (average particle size: 2.2 μm) 30 parts by weight, 4 parts by weight of B-82 (Rohm and Hass) in a PMMA binder, 9 parts by weight of DBP as a plasticizer, 2 parts by weight of glyceryl trioleate as a dispersant, stearic acid as a lubricant 0.5 parts by weight was added to prepare a slurry.

The slurry thus obtained was applied to the mylar film at 200 μm with a tape casting apparatus using a doctor blade, and then dried at 25 ° C. for 24 hours. The dry film thus obtained was laminated by applying pressure on the glass substrate on which the back dielectric and the electrode were printed. In the same manner as in Example 1, prefiring, protective film pattern formation, sand blasting, firing, and the like were produced, whereby a partition for plasma display having a height of 124 µm and a thickness of 43 µm was produced.

The barrier rib manufacturing method on the plasma display back plate provided by the present invention does not require a separate manufacturing process such as a protective film, exposure, development, etc., so that the barrier rib manufacturing apparatus can be simplified and the shape can be uniform.

Moreover, since the protective film obtained by the composition of this invention can be used as a partition by baking, it is possible to suppress the breakage of the partition which arises when a DFR film is released, and the generation | occurrence | production of a micro crack in a partition, and the product reliability of a partition It is possible to improve the yield, improve the yield of the product and improve the uniformity of the quality.

Therefore, the partition wall forming process provided in the present invention can greatly reduce the manufacturing cost of the back plate for the plasma display device.

Claims (6)

In manufacturing the partition on the back plate of the AC plasma display device, (A) mixing a glass and ceramic mixed powder, an organic binder, a dispersant and the like into a solvent to produce a slurry for thick film production; (B) By using the slurry, a thick film is formed on the glass substrate on which the back plate dielectric and the electrode are printed, and prebaked to a predetermined temperature profile to form a relatively porous structure than the following patterned protective film. Forming a dry film having; (C) A paste containing a partition material as a protective film on the dry film is printed by a screen printing method in a pattern of the partition wall and then dried to form a relatively dense patterned protective film in which a binder is more remaining than the dry film. Forming; (D) sand blasting the thick film on which the patterned protective film is formed to form a partition molding by preferentially etching the thick film by an etching rate difference between the thick film and the protective film; And (E) firing the resulting partition molding to form a partition wall. According to claim 1, In the step (A), the composition of the slurry for thick film production, (a) 100 parts by weight of a powder mixture of 50:50 to 95: 5 (volume ratio) of the glass powder and the ceramic powder; (b) 20 to 40 parts by weight of the solvent; (c) 2 to 8 parts by weight of the organic binder; (d) 0.5 to 3 parts by weight of dispersant; And (e) 0 to 12 parts by weight of a plasticizer; In the step (C), the protective film production paste is a partition manufacturing method, characterized in that using a conventional PDP backplane partition wall production paste. The method for producing a partition wall according to claim 1 or 2, wherein the method of forming a thick film on the glass substrate (step (B)) is selected from the following two methods. (1) The slurry from step (A) may be transferred onto a glass substrate using a doctor blade, tape caster, roll coater, extrusion coating, die casting, cap coating apparatus, or the like. A method of directly forming a thick film in one coating process; And (2) The slurry from step (A) was formed on a carrier film such as a mylar film by using a doctor blade method, a tape casting method, or the like, and dried. Thereafter, a secondary thick film is formed on the glass substrate by a lamination process. The method according to claim 1 or 2, wherein, in order to control the etching rate of the formed thick film, in the step (B), prebaking is performed for 0.5 to 1.5 hours in a temperature range of 120 to 300 ° C, and the step (C) And a paste containing the partition material as a protective film at 10 to 30 minutes in a temperature range of 25 to 190 ° C. to maximize the difference in etching rates between the pre-fired thick film and the protective film paste. The method according to claim 1 or 2, wherein when etching by the sandblasting method, the sandblasting angle is varied from 0 ° to 90 ° to maximize the etching rate between the prefired thick film and the protective film paste. Partition wall manufacturing method characterized in that. According to claim 2, wherein the glass powder has an average particle size of 0.2 to 10㎛ PbO-B ₂ O ₃ -SiO ₂ system, B ₂ O ₃ -SiO ₂ -Bi ₂ O ₃ -P ₂ O ₅ system, Bi ₂ One or a mixture of two or more selected from O ₃ -B ₂ O ₃ -ZnO-BaO-SiO ₂ , etc., The ceramic powder may be alumina (Al ₂ O ₃ ), titanium oxide (TiO ₂ ), zirconia (ZrO ₂ ), manganese oxide (MnO), copper oxide (CuO), or iron oxide (a ceramic powder having an average particle size of 0.2 to 10 μm). Fe ₂ O ₃ ) and the like, or a mixture of two or more, The solvent is methyl ethyl ketone, ethyl alcohol, isopropyl alcohol, toluene, toluene, diethyl ether, trichloroethylene, methanol A single solution or a mixed solution of two or more, The organic binder is selected from cellulose, ethyl cellulose, polyvinyl butyral (PVB), polymethyl methacrylate (PMMA), polyacrylate esters, and the like. One or two or more mixtures having an average molecular weight of 30,000 to 100,000, The plasticizer may be selected from diethyl oxalate, polyethylene, polyethylene glycol, dimethyl phthalate, dibutyl phthalate, dioctyl phthalate, or the like. Is a mixture of two or more, The dispersant may include fish oil (menhaden fish oil), polyethyleneimine, glyceryl trioleate, polyacrylic acid, corn oil, glycerine, phosphate ester one or two or more mixtures selected from esters, etc., and the other additives include a coupling agent having different functional groups, tri-methoxypropyl trimethoxysilane, and tri-aminopropyltriethoxy silane. ), A method for producing a partition, characterized in that one or two or more mixtures selected from amino silane (Amino-silane).