Method for manufacturing plasma display unit substrate

Abstract: A method for manufacturing a substrate for a large size plasma display unit with highly accurate and microscopic pitches in a simple process at low cost comprises the steps of mixing ceramic or glass powders with a binder, applying said mix to the back face plate (2) which comprises ceramic or glass, forming bulkheads (3) on the back face plate by rotating a roll (12) having a grooved surface (13) to pressure-patterning the applied mix.

Description: BACKGROUND OF THE INVENTION FIELD OF THE INVENTION The present invention relates to a method for manufacturing flat plate with a precise bulkhead. DESCRIPTION OF THE PRIOR ART The plasma display unit used for thin type large screen color display units, etc. has a construction in which opposite electrodes are installed in the space surrounded with bulkheads called microscopic display cells, and the space is sealed with dischargeable gas such as noble gas, etc., and plasma is generated by discharges between opposite electrodes, and the phosphor is allowed to emit light by the plasma to use it as a light emitting element of the screen. For the specific construction, as shown in FIG. 12, a large number of bulkheads 102 are formed on the whole surface of the back face plate 101, space between each bulkhead 102 and bulkhead 102 is designated as a cell 103, and the substance with an electrode 104 equipped on the bottom surface of this cell 103 is designated as a substrate 105. With respect to this substrate 105, phosphor is applied to the inner wall surface 106 of the cell 103, whereas the front panel 108 with the electrode 107 equipped is joined on the bulkhead 102 of the substrate 105, and gas is sealed in the cell 103 to form a plasma display unit. The electrodes 104, 107 are, in actuality, arranged in such a manner to intersect each other at right angles, but in FIG. 12, they are arranged in parallel for description. Now, in manufacturing the substrate 105 for the plasma display unit, a large number of electrodes 104 are formed on the back face plate 101 then the bulkhead 106 is formed between each electrodes 104, and for the manufacturing method of this bulkhead 106, the print lamination method, additive method, sandblast method, and photosensitive paste method are well known. The print lamination method is to print to form a bulkhead 102 of a specified pattern on the back face plate 101 by the thick film printing method using pastes of the material comprising the bulkhead 102, and since the thickness formed by one printing is about 30 µm, the bulkhead 102 which requires about 200 µm height by repeating printing and drying (see Japanese Non-examined Patent Publication No. Hei 2-213020). The additive method is to apply photosensitive resin on the back face plate 101, to curve grooves by the light on the photosensitive resin, and to embed pulverized glass in the groove to form the bulkhead 102. In addition, the sand blast method is to form a glass layer of a specified thickness on the whole surface of the back face plate 101, on this surface, to form the resist mask in the form of the bulkhead 102 and then, to remove the glass layer of the portion other than the bulkhead 102 by sandblasting (see Japanese Non-examined Patent Publication No. Hei 4-259728). In addition to this, the photosensitive paste method is to apply the paste with photosensitive resin mixed on the back face plate 101, and after masking, to irradiate light to directly form the bulkhead 102. A further method for manufacturing a plasma display unit substrate and a corresponding plasma display unit substrates is disclosed in EP-A-0802170, published on October 22, 1997, and in EP-A-0836892, published on April 22, 1998. These documents form part of the state of the art only under Article 54(3) EPC and do not disclose to use polyvinylbutyral resin for manufacturing the plasma display unit substrate. Therefore it is the object of the invention to provide a manufacturing method for a plasma display unit substrate that can provide a plasma display unit substrate having highly precise bulkheads with a smooth surface free of deformation at a specific height. SUMMARY OF THE INVENTION According to the present invention the above object is achieved by a method according to claim 1, by a method according to claim 5 and by a plasma display unit substrate according to claim 7. The dependent claims are related to further advantageous aspects of the invention. BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1 is a perspective view showing a plasma display unit substrate related to the invention; FIG. 2 is a perspective view showing the outline of the manufacturing method of the invention; FIG. 3 is a longitudinal sectional view showing the condition in which electrodes are affixed to the whole surface of the back face plate by printing related to the invention; FIG. 4 is a longitudinal sectional view showing the condition with the mixture paste adhering to the back face plate; FIG. 5 is a longitudinal sectional view showing the condition of bulkheads formed on the back face plate with a roll; FIG. 6 is a longitudinal sectional view of the back face plate when the electrode paste is applied; FIG. 7 is a longitudinal sectional view showing the condition of the surface shown in FIG. 6 where bulkheads are formed on the back face plate with a roll; FIG. 8 is a longitudinal view of the condition with black-based material applied to the back face plate; FIG. 9 is a longitudinal sectional view showing the condition of the surface shown in FIG. 8 where bulkheads are formed on the back face plate with a roll; FIG. 10 is a longitudinal sectional view showing the condition where the mold releasing agent is affixed to the back face plate; FIG. 11 is a longitudinal sectional view showing the condition where the irregular surface of the back face plate is applied with polyvinylbutyral resin to produce a smooth surface; FIG. 12 is a longitudinal sectional view showing the outline of the conventional plasma display unit; FIG. 13 is a longitudinal sectional view showing the condition with the back face plate applied with the mixture paste; FIG. 14 is a longitudinal sectional view showing the condition with bulkheads formed on the rear face plate by a roll; FIG. 15 is a longitudinal sectional view showing the condition with the mixture paste applied in advance to the back face plate according to the invention; FIG. 16 is a longitudinal sectional view showing the condition where the circumferential grooves of the roll according to the invention are filled first with black-based material powders, then with a mixture paste; FIG. 17 is a longitudinal sectional view showing the condition where black-based material is formed at the tip end of the bulkhead of the back face plate according to the invention; FIG. 18 is a perspective view showing the condition where phosphor holding grooves are carved on the inner wall surface of the bulkhead of the invention; FIG. 19 is a side view showing the condition where a circular arc is formed at the tip end portion on both edges of the bulkhead of the invention; FIG. 20 is a sectional view of a roll ; FIG. 21 is a perspective view of bulkheads formed by the roll of FIG. 20; FIG. 22 is a perspective view of the substrate according to the invention, to which weirs for preventing phosphor from flowing out are equipped; and FIG. 23 is a perspective view of the substrate to which a frame is installed. DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS Referring now to the drawings, preferred embodiments according to the invention will be described in detail hereinafter. As shown in FIG. 1, the substrate 1 for plasma display units is equipped with a plurality of bulkheads 3 comprising ceramics or glass on one surface of back face plate 2 comprising ceramics or glass, and a cell 4 is formed between bulkheads 3. And on the bottom surface of this cell 4, an electrode 5 is equipped, and after phosphor is applied to the inner wall surface 6 of the cell 4, the upper end of the bulkhead 3 is covered with a front plate 108 equipped with an electrode 107 as shown in FIG. 12, and gas is sealed in the cell 4, thereby enabling composing a plasma display unit. And discharging electricity between electrodes 5, 107 allows the phosphor applied to the inner wall surface 6 of the cell 4 to emit light. In actuality, electrodes 5, 107 are arranged to cross at right angles each other. Though not illustrated, it is possible to adopt a 3-electrode system in which the electrode 107 is formed with a pair of electrodes. In this case, the system will be of a plane discharge type in which maintenance discharge is generated between a pair of electrodes 107 and is controlled by the electrode 5 of back face plate 2. Next discussion will be made on the manufacturing method of the substrate 1. FIG. 2 schematically shows the general view. On one surface of the back face plate 2 comprising ceramics or glass shown in FIG. 3, electrodes 5 are formed at specified intervals by screen printing. As shown in FIG. 4, a paste 11 of a mixture of ceramics or glass powders is applied to the back face plate 2 with the electrode 5. Then, as shown in FIG. 5, the surface of a roll 13 having circumferential grooves 12 of a specified width and a specified depth at specified intervals corresponding to bulkheads 3 is brought into contact with the surface applied with the paste 11 after drying, and the roll is pressurized and rotated to form bulkheads 3 on the back face plate 2. That is, by bringing the roll 13 in contact and pressurizing the roll, the paste 11 enters the circumferential grooves 12 of the roll 13 and solidifies, and bulkheads 3 are formed. The pressurizing force of the roll 13 is, for example, about 7 kg per 1 cm of contact length with the paste 11 in the axial direction of the roll 13, and 700 kg at contact length of 100 cm. Thereafter hardening bulkheads 3 by heat treatment can produce the substrate 1. As described above, because according to this invention, all we need is to bring the roll 13 in contact and pressurize and rotate the roll, if the roll 13 is fabricated at a high accuracy in advance, precision bulkheads 3 can be easily formed, and even a large-size substrate 1 can be easily manufactured. The manufacturing method of the invention described above can be applied not only to substrates for plasma display units but also precision bulkheads in various members such as ink jet printer heads or optical communication members. Now, for ceramics powders of the paste 11 forming bulkheads 3, any of oxide based ceramics such as alumina (Al 2 O 3 ), zirconia (ZrO 2 ), etc., nonoxide based ceramics, etc. such as silicon nitride (Si 3 N 4 ), aluminum nitride (AlN), silicon carbide (SiC), etc., or apatite (Ca 5 (PO 4 ) 3 (F, Cl, OH)) can be used, and to these ceramics powders, various sintering assistants may be added in a desired quantity. For the above sintering assistants, a desired quantity of silica (SiO 2 ), calcia (CaO), yttoria (Y 2 O 3 ), magnesia (MgO), etc. can be added to alumina powders, oxides of rare earth elements such as yttoria (Y 2 O 3 ) or cerium (Ce), dysprosium (Dy), ytterbium (Yb), etc. to zirconia powders, yttoria (Y 2 O 3 ), alumina (Al 2 O 3 ), etc. to silicon nitride powders, oxides of periodic table group 3b elements (RE 2 O 3 ), etc. to aluminum nitride powders, boron (B), carbon (C), etc. to silicon carbide powders. For glass powders forming bulkheads 3, various glasses with silicate as a main component and containing one or more kinds of lead (Pb), sulphur (S), selenium (Se), alum, etc. may be used. In addition, forming bulkheads 3 with glass and adding ceramics as a filler can improve the strength and optical characteristics. For example, from the purposes to improve light reflectivity and brightness of the panel, alumina, zirconia, titania, zinc oxide, and other white ceramics are added as required, and from the purposes to improve the light shieldability and panel contrast, nickel oxide, copper oxide, chromium oxide, and other deep color ceramics are added as required in accord with purposes. For the grain size of these ceramics or glass powders, scores of microns to submicrons can be suitably used, and specifically 0.2 to 10 µm, and more preferably 0.2 to 5µm. In addition, examples of organic additives to be added to these ceramics or glass powders include polyvinyl alcohol, polyvinylbutyral, acrylic resin, styrene resin, urethane resin, etc. The solvent to be added to the mixture paste 11 is not particularly limited if it is compatible with the organic additives, and examples include toluene, xylene, benzene, ester phthalein, etc. for aromatic solvents, hexanol, octanol, decanol, oxyalcohol, etc. for higher alcohol, or acetate, glyceride, etc. for esters. In particular, ester phthalein, oxyalcohol, etc. can be suitably used, and in addition, in order to gradually evaporate the solvent, two or more solvents can be combined to use. For the content of the solvent, 0.1 parts by weight or more are required for 100 parts by weight of ceramics or glass powders in order to maintain shape holding capability of the formed product from the viewpoint of moldability, while from the viewpoint of lowering the viscosity of the mixture of ceramics or glass powders and organic additives, 35 parts by weight or lower is more preferable, and 1 to 15 parts by weight is most preferable in view of shrinkage at the time of drying and firing. The material of roll 13 in the invention is not particularly limited, but for example, metal, resin, or rubber can be used, and if required, in order to improve the mold releasing capability or to prevent wear, surface treatment such as surface coating, etc. can be carried out. The grooves formed on the roll 13 are not limited to circumferential grooves but may be parallel to the axial direction of the roll 13. The back face plate 2 is an unsintered green sheet or sintered compact, and the material is not particularly limited, but may be, for example, various ceramic green sheets, various glass substrates, porcelain substrates, etc., and is preferable to have a coefficient of thermal expansion similar to that of the material of bulkhead 3. For glass substrates, for example, soda lime glass or in order to improve the warping point, glass with inorganic filler dispersed or other comparatively inexpensive glass can be used. In the mixture paste 11, in order to improve dispersibility of ceramics or glass powders, for example, polyethylene glycol ether, alkyl sulfonate, polycarbonate, alkyl ammonium salt, and other surfactants may be added, and are preferably contained 0.05 - 5 parts by weight to 100 parts by weight of ceramics or glass powder from the viewpoint of improved dispersibility and thermal decomposition. In addition, for the binder in the mixture paste 11, the hardening catalyst called hardening reaction accelerator or polymerization initiator, etc. can be added. For the hardening catalyst, organic peroxides or azo-compounds may be used, whose example include ketone peroxide, diacyl peroxide, peroxiketal, peroxiester, hydroperoxide, peroxycarbonate, t-butylperoxi-2-ethylhexanoate, bis (4-t-butyl cyclohexyl) peroxydicarbonate, dicumyl peroxide, and other organic peroxides, and azobisisoburyronitrile, and other azo-compounds. Now, other embodiment will be described. In FIG. 6, on the back face plate 2, paste 11 of a mixture of ceramics or glass powders and the binder is applied, and on the applied mixture paste 11, electrode paste 14 is applied. As with the method described above, the roll 13 having a plurality of circumferential grooves 12 is brought in contact with the back face plate, and pressurized and rotated; then, as shown in FIG. 7, bulkheads 3 are formed, and electrode pastes 14 are accurately arranged between the bulkhead 3 and the bulkhead 3, which are designated as electrode 5. If no electrode paste 14 at the tip end of the bulkhead 3 is required, it may be scraped away. In the method described above, an example in which electrodes 5 are accurately arranged between the bulkhead 3 and the bulkhead 3 is described, but when black-based material is installed at the tip end of the bulkhead 3 in order to improve adhesion between the back face plate 2 and the front plate 108 and provide contrast to the image, a black-based material 15 is further applied on the mixture paste 11 as shown in FIG. 8. In the same manner as described above, a roll 13 with a plurality of circumferential grooves 12 is rotated with the roll held in contact with the black-based material 15 as shown in FIG. 9 to form bulkheads 3 on the back face plate 2, and the black-based material 15 can be accurately installed at the tip end of the bulkhead 3. For the black-based material, for example, black glass is used. In addition, in order to positively release bulkheads 3 from molds after forming with the roll 13, as shown in FIG. 10, a mold releasing agent 16 may be applied on the mixture paste 11 affixed to the top surface of the back face plate 2. On the surface of the back face plate 2 comprising ceramics or glass, about ±10 µm irregularities exist, but as shown in FIG. 11, polybutyral resin 17 is applied to smoothen the surface of the back face plate 2 , and on the surface, bulkheads 3 may be formed. Even if there exist slight irregularities on the surface of the back face plate 2, it is possible to rotate the roll 13 smoothly by applying polybutyral resin 17, and the back face plate 2 can be formed accurately on the bulkhead 3. Thereafter, even polybutyral resin 17 exists when heated, the bulkhead 3 moves until it comes in contact with the back face plate 2. The back face plate 2 comprising in this way can be affixed to the front plate 108 without any problem. [EMBODIMENT] EMBODIMENT 1 For the roll 13, on a metal roll 50 mm in diameter by 200 mm long, 900 circumferential grooves 50 µm wide by 200 µm deep were carved at a 220 µm pitch. On the other hand, for the back face plate 2, 200×250 mm soda lime glass sheet was prepared. For the paste 11, low-melting point lead glass powders with alumina and titania added were mixed and kneaded with a binder to make a paste, and was applied to the glass sheet by a doctor blade technique. The roll was pressurized at a pressure of 7 kg/cm from above the film, and as the roll was rotated, the glass sheet was fed at the same time, and bulkheads were formed. The formed product obtained was fired at 550 - 600°C. With the above-mentioned operation, a plasma display unit substrate equipped with bulkheads 40 µm wide by 150 µm high was obtained. EMBODIMENT 2 As with the case of Embodiment 1, a roll with circumferential grooves and glass sheet with the paste applied were prepared. On the paste applied surface, a conductive paste primarily comprising Ag was applied for the electrode paste 14 and dried at 80°C. The roll was pressurized at 7 kg/cm and rotated, and bulkheads were formed on the glass sheet. The formed product obtained was fired at 550 - 600°C. With the above operation, a plasma display unit substrate equipped with bulkheads 40 µm wide by 150 µm high was obtained. In this event, spaces between bulkheads are filled with the conductive paste and functioned as electrodes. EMBODIMENT 3 As with the case of Embodiment 1, a roll with circumferential grooves was prepared. For the paste, a white paste with titania added and a black paste with nickel oxide was added as black-based material 15 were prepared. The white paste was applied on the glass sheet material and dried, and then, the black paste was applied on the white paste applied surface. At 7 kg/cm pressure, bulkheads were formed by the roll. The formed product obtained was fired at 550 - 600°C, and a plasma display unit substrate whose tip end of the bulkhead was black was obtained. EMBODIMENT 4 Polybutyral resin made solvent by the volatile solvent was applied to the glass sheet surface and dried. When bulkheads were formed by the same technique as in the case of Embodiment 1, variations of bulkhead height caused by variation in thickness of glass sheet were ±3 µm in this embodiment, which used to be ±10 µm. As shown in FIG. 13, the paste 211 of a mixture of ceramics or glass powders were filled into circumferential grooves 12 of the roll 13 equipped with circumferential grooves 12 of a specified width and depth at specified intervals in correspondence with the bulkhead 3. Then, as shown in FIG. 14, the roll 13 was brought in contact with the back face plate 2, pressurized and rotated to form bulkheads 3 on the back face plate 2. That is, rotating the roll 13 while in contact with the back face plate 2 causes the paste 211 filled in the circumferential grooves 12 to elect with the profile of circumferential groove 12 maintained, and thereby bulkheads 3 are formed. The pressurizing force of the roll 13 is about 7 kg per 1 cm of contact length with the paste 211 in the axial direction of the roll 13, and 700 kg per 100 cm contact length. Thereafter, hardening bulkheads 3 by heat treatment produces a substrate 1. As described above, according to the invention, only pressurizing and rotating the roll 13 while bringing it in contact with the back face plate is required, and if the roll 13 is fabricated in advance at a high accuracy, bulkheads 3 of high accuracy can be easily formed, and even a large-size substrate 1 can be easily manufactured. While the roll 13 is rotated on the back face plate 2 and at the same time filling the circumferential grooves 12 on the roll 13 with the paste 211 can continuously form even long bulkheads 3. In addition, it is possible to construct in such a manner that the paste 211 is injected from the inside of the roll 13 in such event and it is fed to the circumferential grooves 12. The manufacturing method of the invention described above can be applied to precision bulkheads in various members such as ink jet printer heads or optical communication members in addition to the substrates for plasma display units as with the case described above. For the ceramic powders of the mixture paste 211 for forming bulkheads 3, sintering assistants, and glass powders for forming bulkheads, those used in the previous cases are used. The point to form bulkheads 3 and add ceramics as a filler, grain size of ceramics or glass powders, organic additives to be added to ceramics or glass powders, solvents added to the paste 211 of the mixture, suitable solvents, content of the solvent, material of roll 13, back face plate 2, improvement of dispersibility of ceramics or glass powders in the mixture paste 211, and the binder in the paste 211 of the mixture are all same as with the cases mentioned above. Now, still other embodiment will be described. In FIG. 15, the paste 211 of the mixture of ceramics or glass powders and binders are applied to the back face plate 2 in advance. In this way, on the paste 211 of mixture applied, the roll 13 with its circumferential grooves 12 filled with the mixture paste 211 are rotated to form bulkheads 3 on the back face plate 2. Doing this way allows the paste of the mixture filled in the roll 13 to satisfactorily adhere to the paste 211 of the mixture on the back face plate 2. When a black-based material is provided at the tip end of bulkheads 3 in order to improve the adhesion between the back face plate 2 and the front plate 108 and to provide contrast to the image as shown in FIG. 16, the circumferential grooves 12 of the roll 13 shall be first filled with the black-based material 215, and then the mixture paste 211 is filled. Rotating the roll 13 on the back face plate 2 can form bulkheads 3 with the black-based material 215 provided at the tip end as shown in FIG. 17. For the black-based material, for example, black glass if used. EMBODIMENT 5 For the roll 13, a metal roll 50 mm in diameter by 200 mm long was used, and 900 pieces of circumferential grooves 50 µm wide by 200 µm deep were carved at a 220 µm pitch. For the paste 211, alumina and titania were added to the zinc-based low-melting point glass and blended with a binder to prepare the white paste. To the back face plate 2 comprising 200×250 mm soda lime glass sheet, polybutyral resin which was made into a solution with volatile solvent comprising toluene and ethanol was applied, and the solvent components were dried. The roll was filled with the white paste and dried. The roll was brought in contact with the glass sheet, and glass sheet was fed with the roll rotated, and the paste inside the roll circumferential grooves were transferred on to the glass sheet. The formed product obtained was fired at 550 - 600°C to make a substrate for plasma display units. EMBODIMENT 6 For the black-based material 15, alumina and nickel oxide were added to lead-base low-melting point glass, were mixed to produce a black paste. The roll grooves insides were filled with black paste, and wiping away an excess paste, the black paste was left only at the bottom of the roll circumferential grooves. Thereafter, in the same procedure as in the case of Embodiment 5, plasma display units were prepared. The tip end portion of the obtained bulkheads was formed with black glass. In the substrate 1 for plasma display units of the invention, when phosphor is applied to the inner wall surface 6 of the bulkhead 3, phosphor holding grooves 321 are carved on the inner wall surface 6 in the longitudinal direction as shown in FIG. 18 so that phosphor can be satisfactorily held without dripping. Carving holding grooves in the lateral direction in the inner wall surface 6 is not preferable in view of the strength of bulkheads 3, and holding grooves 321 in the longitudinal direction are preferable for bulkheads 3 from the viewpoint of strength. The depth of the holding grooves 321 is preferably about Rmax 3 - 10 µm in the surface roughness when the inner wall surface 6 is measured with a surface roughness gauge. This is because since the grain size of phosphor is 3 µm, the size of the holding groove 321 is 3µm at minimum, whereas if it is greater than 10 µm, it will have detrimental effects on the strength of bulkheads 3. If holding grooves 321 are formed on bulkheads 3 when bulkheads 3 are released from the circumferential grooves 12 of the roll 13 in the longitudinal direction when bulkheads 3 are formed by the roll 13, no special process if required and holding grooves 321 can be formed at low cost. In order to prevent breakage of the tip ends on both edges of bulkheads 3, as shown in FIG. 19, the tip end portion on both edges are formed in a form of a circular arc 323. When tip end portions on both edges of bulkheads 3 are formed in a form of circular arc 323, no chipping is generated even when the front plate 108 comes in contact. The total length of bulkheads 3 is, for example, about 70 cm, and on both edges of the bulkhead, circular arcs 323 are formed in the range smaller than 3µm in the lengthwise direction. When bulkheads 3 are formed with the roll 13, bulkheads 3 with sufficient height are unable to be formed at the beginning and at the end of forming, and result in a circular arc form 323. That is, by bulkheads 3 are formed with the roll 13 no special process is required for forming a circular arc 323 at the tip end portions on both edges of bulkheads 3, and the circular arcs 323 can be formed at low cost. In addition, the cross-sectional form of circumferential grooves 12 of the roll 13 may be made into a profile that fits to the required bulkheads 3. For example, as shown in FIG. 20, if the bottom surface of the circumferential groove 12 of the roll 13 is made into a recessed curved form, the tip end of bulkheads 3 can be made into a protruded curved form as shown in FIG. 21. EMBODIMENT 7 For the roll 13, on a metal roll 50 mm in diameter by 200 mm long, 900 circumferential grooves 50 µm wide by 200 µm deep were carved at a 220 µm pitch. On the other hand, for the back face plate 2, 200×250 mm soda lime glass sheet was prepared. For the paste, low-melting point lead glass powders with alumina and titania added were mixed and kneaded with a binder to make a paste, and was applied to the glass sheet by a doctor blade technique. The roll was pressurized at a pressure of 7 kg/cm from above the film, and as the roll was rotated, the glass sheet was fed at the same time, and bulkheads were formed. The formed product obtained was fired at 550 - 600°C. With the above-mentioned operation, a plasma display unit substrate equipped with bulkheads 40 µm wide by 150 µm high was obtained. On the inner wall surface of this bulkhead, Rmax 3 - 10 µm longitudinal grooves were formed when the bulkhead was separated from the roll, which could be used for phosphor holding grooves 321. In addition, by forming with a roll, both edges of the bulkhead were short for a specified height, and circular arc forms 323 were able to be formed in the range of less than 3 µm in the lengthwise direction. As the substrate 1 for plasma display units of the invention is shown in FIG. 22, a large number of bulkheads 3 are formed on the back face plate 2. To the inner wall surface of bulkheads 3, phosphor is applied, dripping phosphor collects in the cell 4 between the bulkhead 3 and the bulkhead 3, and there is a fear of the collecting phosphor to flow out of the substrate 1. Therefore, in this invention, weirs for preventing flow-out of phosphor 431 are provided on both edges between bulkheads 3. That is, when bulkheads 3 are formed by rolling the mixture paste 11 applied to the back face surface 2 with a roll 13, leaving the un-rolled portions of the mixture paste 11 at the head end and the tail end can form phosphor flow-out prevention weirs 431 as illustrated. The existence of this flow-out prevention weir 431 can prevent phosphor from flowing out from the cell 4 or flowing into the adjoining cells 4. In this way, the flow-out prevention weir 431 can be formed simultaneously when bulkheads 3 are formed by the roll 13, requires no special process and can offer at inexpensive cost. Because the back face plate 2 is thin, there is a fear of causing warpage at the time of firing. In this invention, as shown in FIG. 23, a frame 432 is formed around the plurality of bulkheads 3 formed. This frame 432 can be formed simultaneously when bulkheads 3 are formed by the roll 13, and as described before, at the head end and the tail end, un-rolled portions of mixture paste 11 are left, and at the same time, un-rolled portions are also left on both side portions, and a frame 432 is formed in such a manner that the frame surrounds the plurality of bulkheads 3 formed. The frame is formed to be higher than the bottom surface of the cell 4 and lower than the tip end surface of bulkheads 3. In this way, the frame 432 is able to be formed simultaneously when bulkheads 3 are formed by the roll 13, and does not need any special process, and can be offered at low price. To this frame, an exhaust system and other apparatus may be easily installed as required. EMBODIMENT 8 For the roll 13, on a metal roll 50 mm in diameter by 200 mm long, 900 circumferential grooves 50 µm wide by 200 µm deep were carved at a 200 µm pitch. On the other hand, for the back face plate 2, 200×250 mm soda lime glass sheet was prepared. For the paste 11, low-melting point lead glass powders with alumina and titania added were mixed and kneaded with a binder to make a paste, and was applied 80 µm thick to the glass sheet by a doctor blade technique. The roll was pressurized at a pressure of 7 kg/cm from above the film, and as the roll was rotated, the glass sheet was fed at the same time, and bulkheads were formed. The formed product obtained was fired at 550 - 600°C. With the above-mentioned operation, a plasma display unit substrate equipped with bulkheads 40 µm wide by 150 µm high was obtained. In this event, the flow-out prevention weirs 431 and the frame 432 were able to be formed as shown in FIG. 22 and 23. On the other hand, bulkheads 3 are able to be formed by filling the circumferential grooves 12 with the mixture paste 11 and bringing them into the back face plate 2 and pressurizing. As shown in FIG. 13, the circumferential grooves 12 of the roll 13 which has circumferential grooves 12 in specified width and depth at specified intervals in correspondence to bulkheads 3 are filled with the paste 211 of a mixture of glass powders and binder. Now as shown in FIG. 14, the roll 13 is brought in contact with the back face plate 2 and rotated while pressurizing to form bulkheads 3. The pressurizing force of the roll 13 is about 7 kg per 1 cm of contact length with the axial direction paste 211 of the roll 13, and 700 kg at 100 cm of contact length. This invention is characterized by the use of polybutyral resin for a binder in order to improve the degreasing capability and to improve green strength of bulkheads 3 by thermal decomposition at the time of sintering bulkheads 3. Decomposition of butyral resin is finished at 250 - 400°C, and the bulkheads 3 are provided with the strength that can stand the pressure of 60 kg/cm 2 or higher as a panel.When bulkheads 3 are formed with the roll 13, resin that is easy to form is used, but bulkheads 3 formed with the resin easy to be formed are subject to thermal deformation. To prevent this, UV curable resin is added, and irradiating with ultraviolet rays cures bulkheads 3 and thermal deformation is not generated. EMBODIMENT 9 For the roll 13, on a metal roll 50 am in diameter by 200 mm long, 900 circumferential grooves 50 µm wide by 200 µm deep were carved at a 220 µm pitch. On the other hand, for the back face plate 2, 200×250 mm soda lime glass sheet was prepared. For the paste 211, low-melting point lead glass powders with alumina and titania added were mixed and kneaded with a binder to make a paste, and was applied to the glass sheet by a doctor blade technique. The roll was pressurized at a pressure of 7 kg/cm from above the film, and as the roll was rotated, the glass sheet was fed at the same time, and bulkheads were formed. The formed product obtained was fired at 550 - 600°C. In this event, the product was heated from 250 to 400°C at a rate of 2°C/min. With the above-mentioned operation, a plasma display unit substrate equipped with bulkheads 40µm wide by 150µm high was obtained. EMBODIMENT 10 Bulkheads were formed with all the conditions same as those of Embodiment 9, with exception that to the paste 211, UV curable epoxy resin was added. After the bulkheads were cured by irradiating with ultraviolet rays, the product was fired in the same manner as with the above case. Because the bulkheads are difficult to be deformed even when butyral resin is softened, the heating rate from 250 to 400°C was able to be increased to 10°C/min. With the above-mentioned operation, a plasma display unit substrate equipped with bulkheads 40 µm wide by 150 µm high was obtained. EFFECT OF THE INVENTION Because this invention intends to be a method for manufacturing flat plates with highly precise bulkheads in which a mixture of ceramics powder or glass powder and the binder is applied to the plate material comprising ceramics or glass and bulkheads are formed on the plate material by rotating the mixture-applied surface with the mixture-applied surface pressurized with the roll surface carved with a plurality of grooves, it is possible to provide a method for manufacturing precision bulkheads at inexpensive cost and reliably. This invention intends to manufacture highly precise bulkheads by a method for manufacturing flat plates with highly precise bulkheads. The invention intends to be a method for manufacturing plasma display unit substrate in which polyvinylbutyral resin is applied to the back face plate comprising ceramics or glass, on the polyvinylbutyral resin, therefore a mixture of ceramics powder or glass powder and the binder is applied, bulkheads are formed on the back face plate by rotating the roll on the mixture-applied surface while pressurizing with the roll surface with a plurality of grooves, and the smoothness of the back face plate and the adhesion between the back face plate and the bulkhead are improved by the polyvinylbutyral resin applied, the roll can be smoothly rotated by applying polybutyral resin even if there are irregularities on the surface of the back face plate, and bulkhead can be formed accurately on the back face plate. The invention intends to be a method for manufacturing plasma display unit substrates in which polyvinylbutyral resin is applied to the back face plate comprising ceramics or glass, on the polyvinylbutyral resin, therefore a mixture of ceramics powder or glass powder and the binder is applied, bulkheads are formed on the back face plate by rotating the roll on the mixture-applied surface while pressurizing with the roll surface with a plurality of grooves, and the smoothness of the back face plate and the adhesion between the back face plate and the bulkhead are improved by the polyvinylbutyral resin applied, it is possible to smoothly rotate, the roll by applying polybutyral resin even if slight irregularities are present on the surface of the back face plate, and to accurately form bulkheads on the back face plate.

Claims: A method for manufacturing a plasma display unit substrate comprising the steps: preparing a back face plate (2) comprising ceramics or glass, applying a polyvinylbutyral resin on the back face plate so as to improve the smoothness of the back face plate (2); applying a mixture of ceramics powder or glass powder and a binder on the polyvinylbutyral resin; forming bulkheads (3) on the back face plate (2) by rotating a roll (13) on the mixture applied surface while pressurizing with the roll surface carved with a plurality of grooves, whereby the adhesion between the back face plate and the bulkhead is improved by the polyvinylbutyral resin. A method for manufacturing a plasma display unit substrate according to claim 1, further comprising the step: applying an electrode paste on the mixture before forming the bulkheads. A method for manufacturing a plasma display unit substrate according to claim 1, further comprising the step of applying a black basis material on the applied mixture. A method for manufacturing a plasma display unit substrate according to claim 1, further comprising the step: applying a mold release agent on the applied mixture. A method for manufacturing a plasma display unit substrate comprising the steps: preparing a back face plate (2) comprising ceramics or glass, applying a polynivinylbutyral resin on the back face plate (2), preparing a roll having a plurality of grooves carved therein filled with a mixture of ceramic powder or glass powder and a binder, bringing the roll in contact with the polyvinylbutyral resin applied on the back face plate (2), and rotating the roll to form bulkheads on the back face plate in order to enable manufacture of a large-size plasma display unit substrate equipped with highly accurate and microscopic pitches, wherein the smoothness of the back face plate (2) is improved by the polyvinylbutyral resin and wherein the adhesion between the back face plate (2) and the bulkheads is improved by the polyvinylbutyral resin. A method four manufacturing a plasma display unit substrate according to claim 5, in which the plurality of grooves carved in the roll are filled first with a black basis material powder before filling the mixture of ceramics powder or glass powder and the binder, so that the bulkheads are formed on the back face plate with the bulkhead tip end formed with the black basis material. A plasma display unit substrate manufactured by a method according to any of the preceeding claims.

Inventors: KATOH MASASHI, NISHIOKA YASUHIKO, SAKASEGAWA KIYOHIRO, YONEYAMA KENICHI, YOSHIDA MAKOTO, KATOH, MASASHI, NISHIOKA, YASUHIKO, SAKASEGAWA, KIYOHIRO, YONEYAMA, KENICHI, YOSHIDA, MAKOTO, Katoh, Masashi, c/o Kyocera Corporation, Nishioka, Yasuhiko, c/o Kyocera Corporation, Sakasegawa, Kiyohiro, c/o Kyocera Corporation, Yoneyama, Kenichi, c/o Kyocera Corporation, Yoshida, Makoto, c/o Kyocera Corporation
Applicants: KYOCERA CORP, KYOCERA CORPORATION
Application year: 1998
Main classification: H01J9
IPC codes: C03C17, H01J9