JP2002313226A - Electrode forming method of thin display device and electrode material - Google Patents

Abstract

PROBLEM TO BE SOLVED: To improve accuracy of the total pitch of a pattern and to prevent the pattern form breaking, when forming a fine pattern extending over a large area in screen printing method. SOLUTION: An electron pattern 19 is formed on a panel substrate 11 by a process of forming an electrode pattern wider than a prescribed width of an electrode wire by screen printing method using a photosensitive paste 14, and a process of applying light exposure on the conductive paste pattern 16 formed by the screen printing method using a photomask 17 having an electrode pattern 18 of which, a width of wiring is narrower than the width of the conductive paste pattern. The electrode pattern 19 is formed through the developing of the pattern, after exposure.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a method of manufacturing an electrode pattern of a thin display device using both screen printing and an exposure method, and more particularly, to a plasma display panel (PDP), a fluorescent display tube (VFD), and a field emission device. The present invention relates to a method of manufacturing an electrode pattern in a thin display device such as a display (FED) by using a photolithography technique from an electrode pattern formed by screen printing to obtain a predetermined electrode pattern width.

[0002]

2. Description of the Related Art As a method of forming a thick film electrode of a thin display device, a screen printing method, a photolithography method, and the like are used in mass production.

The screen printing method uses a screen mask in which openings corresponding to a predetermined pattern are formed in advance, and applies a conductive paste made of a metal powder, an inorganic binder, an organic binder, a solvent, or the like to the pattern openings of the screen mask. Is a method of transferring a conductive paste pattern onto a panel substrate through a substrate, which has been widely used for a long time. FIGS. 4A to 4D are explanatory views showing a method of forming electrodes by screen printing in the order of steps. Panel substrate 51 shown in (a) (not shown in the figure, transparent electrode pattern may be formed in advance)
And a screen 56 in which an emulsion is applied to a mesh knitted with a material such as a metal, which is stretched with an appropriate tension on a screen frame 52 at an appropriate distance (clearance) from the panel substrate 51 shown in FIG. After being aligned with the pattern opening 55 corresponding to the pattern, it is placed flat.

[0004] A squeegee 53 and a conductive paste 54 are arranged on a screen 56. After applying an appropriate printing pressure to the squeegee 53 as shown in (c), the squeegee is moved at a constant speed to the left toward (c). At that time, the conductive paste 54 is extruded from the opening of the electrode pattern 55 formed on the screen 56, and the conductive paste pattern 57 is transferred to the panel substrate 51. As explained above,
The screen printing method has a feature that the conductive paste is applied only to necessary portions, so that the conductive paste is less wasted.

[0005] The photolithography method is a method in which a photosensitive conductive material containing a photosensitive agent is formed on the entire surface of a substrate, and then an electrode pattern is formed by exposure and development. In this method, for example, photocurable Fodel silver (manufactured by DuPont) is used as a sheet-shaped photosensitive conductive material.

FIGS. 5 (a) to 5 (d) are explanatory views showing a method of forming an electrode by a photolithography method using a photosensitive conductive material containing a photo-soluble photosensitive agent in the order of steps. FIG. 5E is an enlarged cross-sectional view of a portion A illustrated in FIG.
A photosensitive conductive material 62 shown in (b) is formed on the entire surface of the panel substrate 61 shown in (a). Examples of the forming method include a method in which a sheet-shaped photosensitive conductive material is attached by lamination, and a method in which a paste-like material is applied and dried on the entire surface by a coater or screen printing. The photomask 64 on which the electrode pattern 63 is formed as shown in (c) and the panel substrate 61 are aligned, and exposed to light such as ultraviolet light to break molecular bonds of the photosensitive agent, and the exposed portion is exposed to an aqueous solution of sodium carbonate or the like. Make it soluble in the developer. By performing the development shown in (d), the conductive material other than the predetermined electrode pattern 65 is removed. In the enlarged view shown in (e), the conductive material is isotropically etched during the development of the electrode pattern.
This shows that the formed electrode pattern 65 has an inverted trapezoidal shape with respect to the panel substrate surface 66.

In the formation of an electrode pattern by the photolithographic method, the pattern accuracy of the total pitch and the pattern line width is superior to that of the screen printing method since the electrode pattern can be formed with the pattern accuracy of the photomask used for exposing the electrode pattern.

[0008]

In the case of screen printing, plate making variations of about ± 0.5 / 10,000 occur with respect to the total pitch of the electrode pattern shown in FIG. As the size of the PDP increases, for example, in the case of a total pitch of 1 meter, a variation of ± 50 μm occurs. The cell pitch at that time is 4
Since the thickness is about 00 μm, the alignment accuracy between the address electrode pattern and the partition pattern on the other substrate, the back substrate, and the bus electrode pattern and the transparent electrode pattern on the front substrate is insufficient, which causes a reduction in manufacturing yield. I have. Also, since the screen plate uses a metal mesh, there is a lower limit on the pattern line width that can form a stable pattern, and as the pattern line width narrows, paste is applied to the panel substrate in the metal mesh part. This makes it harder to break the wire, which increases the probability of disconnection, and limits the improvement in definition.

In the photolithography method, there is a problem that the portion removed from the substrate at the time of developing the electrode pattern is larger than the portion used as the actual electrode pattern, and the use ratio of the conductive material is reduced. Further, when recovering a metal from a developer, a commonly used conductive material includes a conductive material containing silver as a main component, but the cost of recovering silver from a developing waste liquid after development is higher than silver. Is higher than the cost of raw materials, and there is no recovery advantage.

Further, if the development waste liquid contains lead oxide contained in the glass of the inorganic binder component and chromium oxide in the dark pigment, there is a possibility that a problem of environmental pollution may occur. In the step of forming a conductive material on the entire surface of the substrate and forming an electrode pattern by development, the conductive material is isotropically etched during development, so that the electrode shape is in an inverted trapezoidal overhang state. After firing of the electrode pattern and the dielectric layer covering the electrode pattern, the edge of the electrode pattern curls, the effective dielectric layer thickness at the edge of the electrode pattern decreases, and the dielectric strength between the electrode patterns decreases. There were also problems.

[0011]

According to the present invention, in order to solve the above-mentioned problems, an electrode pattern wider than a predetermined electrode pattern line width is formed in advance by screen printing, and then a predetermined electrode pattern is formed by photolithography. By forming a pattern, a method for forming an electrode for a thin display device, which can reduce waste of a conductive material and ensure pattern accuracy of a total pitch and an electrode pattern width, has been found.

According to the first aspect of the present invention, in forming an electrode pattern on a panel substrate of a thin display device, a step of forming an electrode pattern wider than a predetermined electrode line width by a screen printing method using a photosensitive conductive paste. A step of performing exposure by using a photomask on which an electrode pattern having a line width smaller than the line width is formed, and an electrode having a predetermined electrode line width by development after exposure. The method is characterized by comprising a step of forming a pattern.

According to the second aspect of the present invention, in forming an electrode pattern on a panel substrate of a thin display device, a step of forming an electrode pattern wider than a predetermined electrode line width by a screen printing method using a conductive paste; A step of applying a photosensitive resist on the panel substrate on which the electrode pattern is formed, a step of performing exposure using a photomask on which a pattern narrower than the electrode pattern line width formed by screen printing, and a step of exposing Forming an electrode pattern having a predetermined electrode width by a step of forming a resist pattern by later development of the resist and a step of performing physical or chemical etching on the electrode pattern formed by screen printing. It is.

According to a third aspect of the present invention, in the method of forming an electrode for a thin display device, pattern printing is performed using a screen mask having a width of 1 / 10,000 wider than a predetermined electrode width by a total pitch of electrode stripes. It is characterized by the following.

According to a fourth aspect of the present invention, in the method of forming an electrode for a thin display device, two or more layers of a conductive paste containing a dark pigment and the conductive paste not containing a dark pigment are laminated and printed by photolithography. An electrode pattern having an electrode width of the following is formed.

According to a fifth aspect of the present invention, the glass contained in the inorganic binder component of the conductive paste is crystallized glass.

[0017]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS An embodiment of the present invention will be described below using a PDP electrode as an example.

FIGS. 1A to 1E are explanatory views showing an electrode forming method according to the first embodiment in the order of steps. FIG.
FIG. 2F is an enlarged cross-sectional view of a portion A in FIG. In the first embodiment, a case where a photosensitive conductive paste containing a photo-soluble photosensitive agent is used will be described.However, when a photosensitive conductive paste containing a photo-curable photosensitive agent is used,
The difference from the description in this embodiment is that a photomask in which the negative / positive of the pattern of the photomask is inverted is used.

A feature of the first embodiment is that pattern printing is performed by a screen printing method on a photosensitive conductive paste mixed with a photosensitive agent using a screen mask having an opening width larger than the final electrode width. The electrode pattern forming method itself transfers the photosensitive conductive paste pattern 16 onto the panel substrate 11 as shown in (c) by the same method as the screen printing method.

Next, the photomask 17 on which the electrode pattern 18 having the final electrode width shown in FIG.
The conductive paste pattern 16 is aligned with the upper conductive paste pattern 16 and exposed to light such as ultraviolet light of several hundred mJ. By performing development using an alkaline developer such as an aqueous sodium carbonate solution shown in (e), the conductive material other than the conductive paste pattern 19 having a predetermined line width is removed. As shown in (f), the conductive paste pattern 16 is isotropically etched in the developing step, so that the cross-sectional shape of the conductive paste pattern 19 on the glass substrate surface 20 is formed to be substantially rectangular, and in the subsequent firing step. In addition, it is possible to avoid the problem that the edge of the electrode pattern is curled and the dielectric strength is reduced.

FIGS. 2A to 2F are explanatory views showing an electrode forming method according to the second embodiment. The feature of the second embodiment is that a predetermined electrode pattern is formed by physical or chemical etching using a photosensitive resist pattern as a mask instead of using a conductive paste containing no photosensitive agent. Except for using a screen mask having an opening width wider than the final electrode width, the process is the same as the conventional screen printing method up to the step of transferring the conductive paste 24 to the glass substrate 21. After the conductive paste pattern 26 is dried or baked as shown in (c), a photosensitive resist 27 is applied to the entire surface. As the photosensitive resist, a method of forming a liquid resist on the surface of a panel substrate using a coating device such as a roll coater or a slot coater or a method of attaching a dry film resist with a laminator is used. In this embodiment, an example of a positive resist will be described. However, in the case of a negative resist such as a dry film resist, the same effect can be obtained by using a negative / positive inverted photomask. After that, the electrode pattern of the photomask 28 and the conductive paste pattern 26 on the glass substrate 21 are aligned and exposed with light such as ultraviolet rays.
By developing the resist shown in (e), a resist pattern 30 having a predetermined line width is formed. After the conductive material other than the resist is etched with an etching solution such as a nitric acid shown in (f), the resist is peeled off to form the electrode pattern 31. Since the etching of the conductive paste pattern 26 by isotropic etching is the same as in the first embodiment, the cross-sectional shape of the electrode pattern 31 is formed to be substantially square, and the electrode edge curls in the subsequent firing step. In addition, it is possible to avoid the problem of lowering the dielectric strength. In addition, in the case of performing physical etching such as sandblasting using a dry film resist pattern, the progress of etching in the vertical direction increases as the etching progresses, making it difficult for side etching of the electrode pattern to enter. And a preferable shape can be obtained.

FIG. 3 is an explanatory diagram of the third embodiment.
Rear substrate 4 of plasma display panel shown in FIG.
1, an address electrode 40 is formed. FIG. 5 (b)
(D) shows the relative position of each pattern depending on the manufacturing accuracy of the screen mask. The relative positional relationship between the electrode forming position 44 on the substrate surface 45 of the part A and the opening 42 of the screen mask 43 in the part A shown in FIG. The relative positional relationship with the opening 46 of the screen mask 47 in the portion B is shown. Here, assuming that the total pitch shown in FIG. 5A is 1000 mm, the manufacturing accuracy with respect to the total pitch of the screen mask is ± 0.5 /.
Since it is 10,000, the positional accuracy of the pattern with respect to the total pitch of the screen mask is within ± 50 μm. Assuming that the line width of the address electrode 40 is 70 μm, the opening width of the openings 42 and 46 of the mask may be set to 170 μm.

FIG. 5B shows the relative positional relationship between the electrode forming positions 44 and 48 and the openings 42 and 46 of the screen mask when the total pitch at which the electrodes are originally formed and the total pitch of the screen mask are the same. If this screen mask is used, a conductive paste can be applied to the electrode formation position.

FIG. 5C shows the electrode forming positions 44 and 4 when the total pitch of the screen mask is 0.5 / 10,000 larger than the total pitch at which the electrodes are originally formed.
8 shows the relative positional relationship between the opening 8 and the openings 42 and 46 of the screen mask. Also in this case, it can be seen that the conductive paste can be applied to the electrode forming positions at both ends of the total pitch. FIG. 5D shows that the total pitch of the screen mask is 0.5 /
In this case, the conductive paste can be applied to the electrode forming positions at both ends of the total pitch.

That is, by forming the opening width of the screen mask with an opening width that is 1 / 10,000 of the total pitch at which the electrodes are originally formed than the line width at which the electrodes are originally formed, the total pitch of the screen mask can be manufactured. Tolerances can be absorbed. Further, by increasing the opening width of the screen mask, it is possible to prevent disconnection when applying the conductive paste. In this example,
Although the back substrate has been described, the bus electrodes on the front substrate can be formed in a similar manner.

Although the description has been made assuming that the manufacturing accuracy of the total pitch of the screen mask is ± 0.5 / 10,000 of the current technical level, if the manufacturing technology of the screen mask is improved and the manufacturing accuracy is improved, the opening width of the mask will be increased. Can be further narrowed, so that the amount of the conductive material removed in the photolithography step is reduced, and the effect of the present invention can be further exhibited.

The invention according to claim 4 is particularly effective for forming bus electrodes on the front substrate. That is, in the case of the front substrate, there is an effect of improving display contrast by darkening the lower layer of the bus electrode. Metal oxide powder may be used for the dark pigment, and blackening is possible by including at least one, and preferably three or more, of oxides of Fe, Co, Mn, Cu, and Ru. . However, it is preferable not to include the oxide of Cr from the problem of environmental pollution. The conductive powder preferably contains at least one selected from Ag, Pd, Au and Ni. The manufacturing process is the same as the first and second embodiments except that the first electrode pattern is formed by repeating the electrode pattern formation by screen printing described in the first embodiment and the second embodiment a plurality of times. .

It is preferable from an environmental point of view that the glass material contained in the conductive paste to bind the particles of the metal powder with the inorganic binder component does not contain lead oxide. As a glass material containing no lead oxide, SiO ₂ —B ₂ O ₃ —A
l ₂ O ₃ —BaO or BiO—SiO ₂ —B ₂ O ₃ —B
aO-Al ₂ O ₃ system may be used materials composed mainly of.

According to a fifth aspect of the present invention, after the electrode pattern is formed, the electrode pattern material and the dielectric material are prevented from coming into contact with each other and causing a reaction by firing when forming a dielectric layer. At the firing temperature of the layer, the reaction between the electrode pattern material and the dielectric material can be prevented by using a glass material that does not re-soften as the inorganic binder.

[0030]

According to the first to fifth aspects of the present invention,
Combines the characteristics of not wasting screen printing materials and the ability to form electrodes with high precision and high precision by the photolithography method, and realizes an environment-friendly method for forming electrodes for plasma display panels, and the manufacturing cost of plasma display panels Can be reduced.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of an electrode forming method according to a first embodiment.

FIG. 2 is an explanatory diagram of an electrode forming method according to a second embodiment.

FIG. 3 is an explanatory diagram according to a third embodiment.

FIG. 4 is an explanatory diagram of an electrode forming method by a screen printing method.

FIG. 5 is an explanatory diagram of an electrode forming method by a photolithographic method.

[Explanation of symbols]

 DESCRIPTION OF SYMBOLS 11 Panel board 12 Screen mask 13 Squeegee 14 Conductive paste 16 Conductive paste pattern 17 Photomask

Continued on the front page (51) Int.Cl. ⁷ Identification code FI Theme coat II (reference) G03F 7/40 521 G03F 7/40 521 F term (reference) 2H025 AA00 AB17 AC01 AD01 AD03 CC12 FA03 FA17 FA39 FA40 FA42 FA47 2H096 AA00 BA20 CA05 DA02 GA08 HA17 HA30 JA04 5C027 AA02 5C040 GC19

Claims (5)

[Claims] A step of forming an electrode pattern wider than a predetermined electrode line width by a screen printing method using a photosensitive conductive paste in forming an electrode pattern on a panel substrate of the thin display device; Exposing the formed electrode pattern using a photomask on which an electrode pattern having a line width smaller than the line width is formed, and developing the electrode pattern after the exposure to form an electrode having the predetermined electrode line width. An electrode forming method for a thin display device, comprising a step of forming a pattern. 2. A method of forming an electrode pattern on a panel substrate of a thin display device, comprising the steps of forming an electrode pattern wider than a predetermined electrode line width by a screen printing method using a conductive paste; A step of applying a photosensitive resist on the formed panel substrate, and a step of performing exposure using a photomask on which a pattern narrower than the electrode pattern line width formed by screen printing is formed. A step of forming a resist pattern by developing a resist, and a step of physically or chemically etching the electrode pattern formed by screen printing, wherein the electrode pattern having the predetermined electrode width is formed. A method for forming an electrode of a display device. 3. The screen printing of the electrode pattern according to claim 1, wherein the screen printing of the electrode pattern is performed using a screen mask having a width of 1 / 10,000 wider than a predetermined electrode pattern line width by a total pitch of the electrode pattern. Item 3. An electrode forming method for a thin display device according to item 2. 4. The method according to claim 1, wherein two or more layers of the conductive paste containing a dark pigment and the conductive paste containing no dark pigment are printed. Method for forming an electrode of a thin display device. 5. The electrode material for a thin display device according to claim 1, wherein the glass contained in the inorganic binder component of the conductive paste is crystallized glass.