JP3666937B2 - Thick film pattern forming method - Google Patents

Description

[0001]
[Industrial application fields]
The present invention relates to a method for forming a thick film pattern in a manufacturing process of a liquid crystal display device, a fluorescent display device, a plasma display panel, a hybrid integrated circuit, etc., and in particular, a thick film pattern formation suitably used for a barrier forming method for a plasma display panel. It is about the method.
[0002]
[Prior art]
In general, a plasma display panel, which is a gas discharge panel, has a large number of cells as minute discharge spaces sandwiched between two substrates, and each cell emits light by emitting light, or phosphor is generated by ultraviolet rays generated. Is made to emit light. Between these micro cells, a barrier is provided in order to prevent mutual interference between the cells and to keep the distance between the two substrates constant. In a normal case, this barrier is formed by patterning by screen printing on one substrate using a barrier forming paste.
[0003]
By the way, in the plasma display panel described above, in order to obtain as high luminance light emission as possible by making the discharge space as large as possible, a wall having vertical walls and a narrow and high barrier is required. In particular, a high-definition display requires a high aspect ratio barrier such as a width of 30 to 50 μm with respect to a height of 100 μm, for example. However, since the film thickness that can be formed by one printing in the above-mentioned screen printing is at most several tens of μm, it is necessary to repeat printing and drying many times, generally 10 times or more, resulting in poor productivity. There is a point. In addition, since the coating formed by screen printing has a concave shape at the periphery and becomes convex, there is a problem that sagging will accumulate and the bottom part will spread if overprinted many times, making the barrier finer There were limits. Further, in screen printing, there is a problem that pitch accuracy is limited due to distortion of the printing plate, and it cannot cope with an increase in the size of the panel.
[0004]
As a method for solving such a problem, a barrier formation method using a subtractive method has been proposed (Electronic Materials, 1983, No. 11, p138). That is, after the barrier formation layer is formed, a subtractive resist mask is formed on the upper surface by printing or photolithography, and the barrier formation material in the opening of the resist mask is removed. Among them, a so-called sand blasting method in which fine etching mixed with compressed gas is performed at high speed to perform physical etching is particularly expected. If this sandblasting method is used, it is possible to process the barrier material into a desired shape having a narrow wall surface and a narrow width and a high height. Further, by adopting a photolithography process for resist patterning, the pattern accuracy can be increased, so that it is possible to cope with an increase in size.
[0005]
[Problems to be solved by the invention]
Although the sandblasting method has the advantages as described above, grinding requires a large amount of energy and powder (grinding material), and the time required for grinding is long. In addition, there is a problem that the constituent material such as the gap between the barrier patterns or the electrode, the dielectric layer, and the glass substrate exposed to the periphery of the panel is damaged by sandblasting. For this reason, the barrier forming layer to be ground is required to be ground as easily as possible.
[0006]
By the way, the barrier-forming material generally contains ceramic powders such as alumina and zirconia that do not soften during the firing process and low melting point glass powder that flows and adheres during the firing process. Further, in order to form these powders before firing, a glass paste containing a small amount of resin that can be burned off by vaporization, combustion, decomposition, etc. by firing is used. In order to easily grind the barrier-forming material having such a structure, it is preferable that the powder is filled as loosely as possible, the porosity is high, and the adhesion between the powders is weak. In order to achieve this, the following means are specifically taken.
(1) Minimize the amount of resin used.
(2) A large powder is used, or a powder having a high non-sphericity and a low filling rate is used.
(3) A fragile resin having low flexibility is used.
[0007]
However, the barrier-forming materials that are easily ground by these methods have low mechanical strength, especially when water or alkaline aqueous solution penetrates, resulting in extremely low strength. In addition, since the barrier material in the surface portion is brought to the peeled resist, there arises a problem that the smoothness of the surface is deteriorated. For this reason, there was a limit in improving the ease of grinding of the barrier material. Note that this is not limited to the above-described barrier formation of the plasma display panel, and generally a problem also occurs when a thick film pattern is formed by a subtractive method.
[0008]
The present invention has been made in view of such circumstances, and its object is to form a thick film pattern by the subtractive method and to facilitate the grinding of the pattern forming material and the surface smoothness of the finished pattern. An object of the present invention is to provide a method for forming a thick film pattern in which both are satisfied.
[0009]
[Means for Solving the Problems]
In order to achieve the above object, a first method according to the present invention includes a step of forming a pattern forming layer made of a pattern forming material mainly composed of an inorganic powder and a resin binder on an object, and the pattern formation. Thick film pattern formation including a step of forming a resist pattern on a layer, a step of removing a pattern forming material corresponding to the resist opening, a step of peeling the resist, and a step of sintering the pattern forming material by firing In the method, the step of swelling the resin binder in the pattern forming material with a solvent is performed before the step of stripping the resist.
[0010]
In order to achieve the same object, the second method according to the present invention includes a step of forming a pattern forming layer made of a pattern forming material mainly composed of inorganic powder and a resin binder on an object, A thickness including a step of forming a resist pattern on the pattern forming layer, a step of removing the pattern forming material corresponding to the resist opening, a step of peeling the resist, and a step of sintering the pattern forming material by firing. In the film pattern forming method, a step of impregnating a pattern forming material with a polymer solution or a polymer dispersion is performed before the step of stripping the resist.
[0011]
In the following, the present invention will be described in detail by taking the barrier formation of a plasma display panel as an example, but the present invention can be widely applied when a thick film pattern is formed by a so-called subtractive method, and in particular, a sandblast method. It should be noted that this is effective when pattern processing is performed. The “thick film” as used in the present invention is a film obtained by dispersing inorganic powder such as metal, ceramic, glass, etc. in a vehicle, and fixing it after applying it. It does not mean that. Incidentally, the present invention can also be applied to pattern formation with a film thickness of about 2 μm.
[0012]
The resin binder used in the barrier forming material, which is a pattern forming material, needs to burn / decompose / vaporize at a low temperature so that carbides do not remain in the barrier. Cellulosic resins, acrylic resins, poly-α- Methyl styrene, polyvinyl alcohol and the like are preferably used.
[0013]
The barrier forming layer is formed by applying a coating liquid inked with a volatile solvent, applying the coating liquid on a substrate, and then drying by heating. As the coating method of the barrier forming layer, screen printing, blade coating, comma coating, reverse roll coating, spray coating, gun coating, extrusion coating, lip coating, etc. are preferably used. The ink used here is a paste-like coating liquid kneaded by a roll mill using a low-volatile solvent as used in screen printing, or a slurry-like coating liquid kneaded by a ball mill or the like. Either can be used.
[0014]
The application is generally performed on a glass substrate, but in some cases, the application can be performed on a film and transferred onto the glass substrate. It is also possible to form a barrier forming layer and a resist layer on the film side and transfer them simultaneously to the glass substrate.
[0015]
In the first method, as described above, the resin binder is swollen with a solvent before the resist is peeled off. The term “solvent” as used herein refers to organic compounds that are liquid at room temperature, and generally includes those that are used as surfactants or plasticizers. As a method for swelling the resin binder with this solvent, a method of immersing in a solvent, a method of spraying a solvent mist, a method of exposing to a solvent vapor, or the like is used. By swelling the resin binder with the solvent in this way, the volume of the resin binder is increased and the fixing force between the powders is increased. Further, flexibility is imparted to the resin binder which has been excluded from flexibility in order to facilitate grindability in sand blasting, and strength that opposes the pressure caused by spraying or the pressure caused by an air gun is generated.
[0016]
As the solvent used when immersed in the solvent, a solvent that does not dissolve the resin binder easily but only swells is preferably selected. For example, when the resin binder is ethyl cellulose having an ethoxyl group content of about 48 to 49.5% that is generally used, isopropanol, normal propanol, diacetone alcohol, glycol diacetate, methyl cellosolve, carbitol, cyclohexane, Terpineol can be used. Also, high boiling point compounds such as glycerin, dibutyl phthalate, dioctyl phthalate can be used. Also, a mixed solution system can be used. In a method of spraying a solvent mist or a method of exposing to a solvent vapor, a solvent having higher solubility can be used.
[0017]
It is possible to proceed to the resist stripping step immediately after the swelling step, but an appropriate drying step may be performed to adjust the amount of solvent contained in the thick film pattern. When the solvent used is highly volatile, room temperature drying is sufficient, but when a low volatile solvent is used, drying with heating or reduced pressure is preferably performed.
[0018]
In the second method, as described above, the polymer solution or polymer dispersion is impregnated before the resist is stripped. As the impregnation method, a method of immersing in a polymer solution or polymer dispersion or a method of spraying a mist of the polymer solution or polymer dispersion is used. By impregnating the pattern forming material with the polymer solution or the polymer dispersion in this manner, the adhesion between the powders increases and flexibility is imparted.
[0019]
The solvent or dispersion medium used here is preferably one that does not readily dissolve the resin binder. In addition, the polymer needs to be burned / decomposed / vaporized at a low temperature during the baking process, and examples thereof include cellulose resins, acrylic resins, poly-α-methylstyrene, polyvinyl alcohol, and polyethylene oxide. For example, when the resin binder is ethyl cellulose having an ethoxyl group content of 49.5% or more, a methanol solution or an ethanol solution of ethyl cellulose having an ethoxyl group content of 48 to 49.5% can be used. Further, a diacetone alcohol solution of nitrocellulose, an isopropanol / water mixed solution of cellulose acetate propionate, or the like can be used. Also, aqueous solutions or dispersions such as an aqueous solution of polyvinyl alcohol, an aqueous solution of polyethylene oxide, an aqueous solution of hydroxyethyl cellulose, and an acrylic latex emulsion can be used.
[0020]
Although the resist pattern can be directly patterned by printing, it is preferable to use a photoresist as a resist material and use a photolithography method when performing high-definition processing in a large area. As the photoresist, either a dry film resist or a liquid resist can be used, and they can be used in combination. The resist includes an alkali development type, a water development type, and an organic solvent development type, and an alkali development type or a water development type that has little influence on the environment is preferably used.
[0021]
The resist is preferably removed using a remover. A method of spraying a stripping solution from above the panel by spraying is preferably performed in order to obtain mass production stability. Moreover, the baking process after resist peeling is suitably performed at a peak temperature of 500 to 600 ° C. in an oxidizing atmosphere.
[0022]
[Action]
In the thick film pattern forming method of the present invention having the above-described configuration, the adhesion force between the powders is increased and the resin binder is given flexibility before the resist peeling step. The resist can be peeled off satisfactorily even when a pattern forming material that is easy to grind by a subtractive method is used.
[0023]
【Example】
Hereinafter, examples of the present invention will be described together with comparative examples with reference to process diagrams shown in FIGS. 1 and 2. Here, a case where a barrier is formed on the back plate of the plasma display panel is taken as an example.
[0024]
(Example 1)
First, as shown in FIG. 1A, after an electrode 2 is formed on a substrate 1 made of glass and a dielectric layer 3 is formed thereon, the following composition A (weight%) as a barrier forming material 4 is further formed. ) Glass paste was applied by a reverse roll coater. And after drying for 30 minutes at 100 degreeC with a hotplate, it further dried for 20 minutes at 150 degreeC, and obtained the coating film with an average film thickness of 160 micrometers.
[0025]
<Composition A>
Glass frit (Nippon Electric Glass, GA-21) 46.7
Ground brown alumina (Fujimi Abrasives Industry Co., Ltd., WA # 8000) 12.0
Black pigment (manufactured by Root Special Chemical, heat-resistant black 4200) 18.1
Ethylcellulose (manufactured by Nisshin Kasei Co., Ltd., etosel std. 20) 1.3
Terpineol 10.2.
Butyl carbitol acetate 10.2
Triphenyl phosphate 0.5
Di-2-ethylhexyl phthalate 1.0
[0026]
Next, the substrate 1 was heated to 80 ° C., and a dry film resist 5 was laminated as shown in FIG. The dry film resist 5 used is “NCP225” manufactured by Nippon Synthetic Chemical Industry. Next, as shown in FIG. 1C, exposure was performed with ultraviolet rays through a line pattern mask 6 having a line width of 80 μm and a pitch of 220 μm. The exposure conditions are an intensity of 220 μW / cm ² and an irradiation amount of 120 mJ / cm ² at 364 nm. After the exposure, spray development was performed at a liquid temperature of 30 ° C. with a 1 wt% sodium carbonate aqueous solution. Through the above steps, a resist pattern 7 for sandblasting having a line width of 80 μm and a pitch of 220 μm was obtained as shown in FIG.
[0027]
After the resist pattern 7 was formed, it was dried and aged at 50 ° C. for 2 hours, and then unnecessary portions were removed by sandblasting as shown in FIG. In this case, the distance between the nozzle and the substrate 1 was 10 cm, and sandblasting was performed at a jetting pressure of 3 kg / cm ² using brown fused alumina # 1000 as the abrasive. The grinding time for a diagonal 20 inch substrate was 45 minutes.
[0028]
After the sandblasting process was completed, the entire substrate 1 was immersed in isopropanol as the solvent 8 as shown in FIG. After 5 seconds, it was taken out and dried at room temperature for 5 minutes.
[0029]
Then, as shown in FIG.2 (c), the resist pattern 7 was peeled using the peeling liquid. Specifically, a 2.0 w% aqueous solution of sodium hydroxide was used as the stripping solution, and spray stripping was performed at 30 ° C. And after giving water washing, it dried for 15 minutes in 80 degreeC oven. Next, firing was performed at a peak temperature of 560 ° C., and a barrier forming material was bound as shown in FIG. Thereby, there was no damage such as chipping, and a good barrier 9 having a high surface smoothness was formed. Moreover, the disconnection of the electrode 2 did not occur.
[0030]
(Comparative Example 1)
In Example 1, after completion of the sandblasting process, the resist pattern 7 was peeled off without being immersed in isopropanol, and then fired at a peak temperature of 560 ° C. to bind the barrier forming material to the substrate 1. When the barrier formed in this way was observed with a microscope, a large number of chips of 50 μm or more were found. Further, unevenness of about 5 μm was observed on the entire surface.
[0031]
(Example 2)
In Example 1, instead of immersing the substrate 1 after the sandblasting treatment in the solvent, the following steps were performed. That is, a 10 wt% solution in which nitrocellulose (1/2 second RS, manufactured by Hercules Co., Ltd.) was dissolved in diacetone alcohol was sprayed with a sprayer and sprayed on the substrate 1. And after drying for 15 minutes at 60 degreeC, the barrier formation material was bound through the peeling process and baking process of the resist pattern 7 similarly to the Example. Also in the present example, a good barrier 9 having a shape with high surface smoothness and no damage such as chipping was formed. Moreover, the disconnection of the electrode 2 did not occur.
[0032]
【The invention's effect】
As described above, the thick film pattern forming method of the present invention is to swell the resin binder in the remaining pattern forming material with a solvent after removing the pattern forming material corresponding to the resist opening by the subtractive method, Alternatively, the resist peeling process is performed after the pattern forming material is impregnated with the polymer solution or polymer dispersion, so that the adhesion force between the inorganic powders in the pattern forming material is increased and the subtractive grinding is performed. Since the flexibility is added to the resin binder that has been removed from the flexibility to facilitate the process, the resist forming process takes the surface part of the patterning material to the resist or damages the patterning material. A thick film pattern with good surface smoothness can be obtained.
[Brief description of the drawings]
FIG. 1 is a process diagram of the first half showing an embodiment of a thick film pattern forming method according to the present invention.
2 is a process diagram of the latter half subsequent to FIG. 1. FIG.
[Explanation of symbols]
1 Substrate 2 Electrode 3 Dielectric layer 4 Barrier forming material (pattern forming material)
5 Resist 6 Mask 7 Resist pattern 8 Solvent 9 Barrier

Claims (8)

Corresponding to a step of forming a pattern forming layer made of a pattern forming material mainly composed of an inorganic powder and a resin binder on an object, a step of forming a resist pattern on the pattern forming layer, and a resist opening In the thick film pattern forming method including the step of removing the pattern forming material, the step of peeling the resist, and the step of sintering the pattern forming material by baking, the step of removing the resist before the step of peeling the resist A method for forming a thick film pattern comprising the step of swelling a resin binder with a solvent. 2. The thick film pattern forming method according to claim 1, wherein the step of removing the pattern forming material corresponding to the resist opening is performed by a sandblast method. 3. The thick film pattern forming method according to claim 1, wherein the thick film pattern to be formed is a barrier of a plasma display panel. 4. The thick film pattern forming method according to claim 1, wherein the resist material is peelable with an alkaline aqueous solution, and the resin binder in the pattern forming material is water-insoluble. Corresponding to a step of forming a pattern forming layer made of a pattern forming material mainly composed of an inorganic powder and a resin binder on an object, a step of forming a resist pattern on the pattern forming layer, and a resist opening In the thick film pattern forming method including the step of removing the pattern forming material, the step of stripping the resist, and the step of sintering the pattern forming material by baking, the polymer is applied to the pattern forming material before the step of stripping the resist. A method for forming a thick film pattern comprising the step of impregnating with a solution or a polymer dispersion. 6. The thick film pattern forming method according to claim 5, wherein the step of removing the pattern forming material corresponding to the resist opening is performed by a sandblast method. 7. The thick film pattern forming method according to claim 5, wherein the thick film pattern to be formed is a barrier of a plasma display panel. 8. The thick film pattern forming method according to claim 5, 6 or 7, wherein the resist material can be peeled off with an alkaline aqueous solution, and the resin binder in the pattern forming material is water-insoluble.

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