Classifications

• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel
  • H01J11/20—Constructional details
  • H01J11/22—Electrodes, e.g. special shape, material or configuration
  • H01J11/24—Sustain electrodes or scan electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01B—CABLES; CONDUCTORS; INSULATORS; SELECTION OF MATERIALS FOR THEIR CONDUCTIVE, INSULATING OR DIELECTRIC PROPERTIES
  • H01B1/00—Conductors or conductive bodies characterised by the conductive materials; Selection of materials as conductors
  • H01B1/20—Conductive material dispersed in non-conductive organic material
  • H01B1/22—Conductive material dispersed in non-conductive organic material the conductive material comprising metals or alloys
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J11/00—Gas-filled discharge tubes with alternating current induction of the discharge, e.g. alternating current plasma display panels [AC-PDP]; Gas-filled discharge tubes without any main electrode inside the vessel; Gas-filled discharge tubes with at least one main electrode outside the vessel
  • H01J11/10—AC-PDPs with at least one main electrode being out of contact with the plasma
  • H01J11/12—AC-PDPs with at least one main electrode being out of contact with the plasma with main electrodes provided on both sides of the discharge space
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J9/00—Apparatus or processes specially adapted for the manufacture, installation, removal, maintenance of electric discharge tubes, discharge lamps, or parts thereof; Recovery of material from discharge tubes or lamps
  • H01J9/02—Manufacture of electrodes or electrode systems
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2211/00—Plasma display panels with alternate current induction of the discharge, e.g. AC-PDPs
  • H01J2211/20—Constructional details
  • H01J2211/22—Electrodes
  • H01J2211/225—Material of electrodes
• • H—ELECTRICITY
  • H01—ELECTRIC ELEMENTS
  • H01J—ELECTRIC DISCHARGE TUBES OR DISCHARGE LAMPS
  • H01J2211/00—Plasma display panels with alternate current induction of the discharge, e.g. AC-PDPs
  • H01J2211/20—Constructional details
  • H01J2211/34—Vessels, containers or parts thereof, e.g. substrates
  • H01J2211/44—Optical arrangements or shielding arrangements, e.g. filters or lenses
  • H01J2211/444—Means for improving contrast or colour purity, e.g. black matrix or light shielding means

Definitions

• the present invention relates to an electrode composition for plasma display panels (PDP), and more particularly to improvements in the conductive components included in black bus electrodes.
• PDP plasma display panels
• black components are included in the bus electrodes of the front panel to improve the contrast.
• Single- and double-layered types of bus electrodes are known in the art.
• a black component is included along with a conductive component such as silver in the single-layered type.
• a white electrode containing a conductive component such as silver is stacked with a black electrode (black bus electrode) containing the black component.
• Ruthenium oxide e.g. Japanese Patent JP3779297), Co 3 O 4 (JP3854753), Cr-Cu-Co (US patent publication 2006- 0216529), lanthanum compounds (JP3548146), and CuO-Cr 2 O 3 -Mn 2 O 3 (JP3479463) are known as black components.
• Black components with a high degree of blackness are preferred for improving the contrast in PDP. Blackness is usually assessed as the L value in PDP. On the other hand, low contact resistance is also an element that is considered important as well as blackness. Because black components have higher resistance than conductive metals such as silver or copper, there has long been a need to find a way to combine the mutually conflicting factors of lower contact resistance and higher blackness to improve contrast.
• Ruthenium oxides and ruthenium compounds have a high degree of blackness as the black component and are also conductive, and have conventionally been preferred for use to obtain high blackness and low contact resistance in PDP.
• a highly conductive, inexpensive metal for example copper, nickel or palladium
• copper characteristically tends to oxidize, and must therefore be sintered in a reducing atmosphere.
• nickel has relatively low conductivity. Palladium releases oxygen, particularly during reduction, as a result of the redox reaction during the sintering process, and thus results in a considerable loss of the bus electrode properties.
• JP2002-299832 also discloses a technique in which Pd-containing Ag prepared by co-precipitation is used to form electrodes on a glass substrate. It is claimed that this results in better adhesion between the glass substrate and the electrodes, low resistance, and better migration resistance.
• JP2002-299832 is characterized by the use of Ag and Pd co- precipitated powder instead of a mixture of Ag powder and Pd powder or Ag-Pd alloy (Paragraph 0011 ). PDP electrodes were disclosed as the electrode application.
• the current invention relates to adding a small amount of a precious metal to a black electrode to enable the formation of a black bus electrode having higher blackness, having lower contact resistance and having less Ag-induced yellowing of the panel.
• the present invention is a conductive composition for a black bus electrode for plasma display, comprising a conductive powder, glass powder, organic binder, organic solvent, and black pigment, wherein the conductive powder is platinum particle or gold particle.
• the present invention is also a front panel of a plasma display panel on which bus electrodes are formed, wherein the bus electrodes have a black-and-white double-layered structure comprising a black electrode and a white electrode, and the black electrode comprises platinum or gold as conductive particle.
• the conductive composition of the present invention is used to form a black bus electrode that has a high degree of blackness and low contact resistance. It was evident that the prescribed precious metal provided low contact resistance even when added in low amounts such as 0.01 -1.0 wt% based on the total amount of the composition.
• FIG. 1 is a perspective expansion plan schematically illustrating an AC plasma display panel device
• Fig. 2 illustrates a series of processes for producing double- layered bus electrodes on a glass substrate with transparent electrodes, with each figure illustrating (A) the stage where a paste for forming black bus electrodes is applied, (B) the stage where a paste for forming white electrodes is applied, (C) the stage where a given pattern is exposed to light, (D) the development stage, and (E) the sintering stage; and
• the present invention provides a composition that is used for black electrodes in cases where the bus electrode is the double-layered type comprising a white electrode and black electrode.
• black electrodes of the double-layered type are described as black bus electrodes.
• a first embodiment of the invention relates to a conductive composition for a plasma display black bus electrode, comprising a conductive powder, glass powder, organic binder, organic solvent, and black pigment, wherein the conductive powder is platinum particle or gold particle.
• the constituents of the conductive composition in the invention will first be described in order.
• the conductive composition of the invention is ordinarily in the form of a paste.
• the conductive powder is added for vertical (the direction in which the electrodes are stacked) conduction in black bus electrodes.
• Precious metal is used as a conductive powder.
• the precious metal is platinum(Pt) or gold(Au).
• a mixture of platinum and gold can be used and such embodiment is within the scope of the present invention. It has been found that platinum and gold works efficiently as conductive metal in black electrodes of PDP front panel, even in the case where a small amount is added in paste. Other precious metal particles are inferior as compared with gold and platinum, due to oxidation during sintering and other deleterious issues.
• the conductive powder of the present invention can be manufactured by conventional method for metal particles. Commercially available powder can be used.
• the configuration of the conductive powder is not particularly limited, and may be in the form of spherical particles or flakes (rods, cones, or plates).
• the mean particle diameter (PSD D50) of the conductive powder is preferably 0.1 to 5 ⁇ m. If a particle has too small of a particle diameter it tends to result in greater contact resistance, making it necessary to increase the amount of the conductive powder that is added. Too great a particle diameter tends to result in higher costs and poses the danger of damage due to the substantial protrusion of particles at the surface where the electrode is formed.
• the mean particle diameter (PSD D50) means the particle diameter corresponding to 50% of the integrated value of the number of particles when the particle size distribution is prepared.
• the particle size distribution can be prepared using a commercially available measuring device such as the X100 by Microtrac.
• the mean particle diameter (PSD D50) of the conductive powder is preferably 0.8 to 2.0 times, more preferably 1.0 to 1.8 times, still more preferably 1.0 to 1.6 times the thickness of the sintered film of the black bus electrodes that are formed.
• the current flows in the direction, in which the white and black electrodes are stacked, on account of the PDP structure.
• the bus electrodes are formed on an ITO electrode, the current flows in the direction from the ITO electrode ⁇ black bus electrode ⁇ white electrode.
• the conductive powder is therefore preferably capable of ensuring conductivity in that direction.
• the mean particle diameter of the conductive powder is more than 1 times the thickness of the sintered film of the black bus electrode that is formed, most of the conductive powder will be in contact with both the white electrode and the transparent electrode such as the ITO electrode. In this case the contact resistance will be low.
• the upper limit of the mean particle size is not restricted in terms of contact resistance, however, large particles may cause some problems like wash-off of the particle during manufacturing process.
• a process for sintering the TOG forming the dielectric is required after the electrode formation in the PDP manufacturing process, but an unexpected effect is that the contact resistance can be lowered after the TOG sintering process.
• the paste for producing the black stripes and the paste for producing the black bus electrodes may sometimes be the same, as disclosed in JP2004-063247A, and the present invention is particularly useful when such a process is adopted.
• Ag is included in the black stripe, yellowing caused by the diffusion of Ag can become a particular problem, but the use of the conductive powder of the present invention prevents such Ag diffusion-induced yellowing.
• the content of the precious metal is preferably less than 1.Owt%, more preferably less than 0.5wt%, and still more preferably less than 0.25wt% in terms of promoting better blackness and reducing material cost.
• the lower limit of the precious metal is preferably more than 0.01 wt%, more preferably more than 0.05wt%, and still more preferably more than 0.1 wt% in terms of conductivity between the transparent electrode and the white electrode.
• the content of the conductive powder may be extremely low since there is no need for horizontal conduction to be taken into account.
• the amount of the conductive powder is preferred to be lower from the standpoint of controlling the costs associated with the precious metal.
• increasing precious metal content may lead to some increase in L-value, so for better blackness (i.e. lower L-value) lower levels of precious metal are preferred.
• enough of the conductive powder is to be added to bring about the effects of the present invention.
• a glass powder is used as a binder in the present invention to promote sintering of the conductive powder or black pigment components in the black bus electrodes.
• the glass powder used in the invention is not particularly limited. Powder with sufficiently low softening point to ensure adhesion with the substrate is normally used.
• the softening point of the glass powder is normally to be 325 0 C to 700 0 C, preferably 35O 0 C to 65O 0 C, and more preferably 375 0 C to 600 0 C. If melting takes place at a temperature lower than 325 0 C, the organic substances will tend to become enveloped, and subsequent degradation of the organic substances will cause blisters to be produced in the paste.
• a softening point over 700 0 C will weaken the paste adhesion and may damage the PDP glass substrate.
• Types of glass powder include bismuth-based glass powder, boric acid-based glass powder, phosphorus-based glass powder, Zn-B based glass powder, and lead-based glass powder.
• the use of lead-free glass powder is preferred in consideration of the burden potentiality imposed on the environment by the use of lead based powder
• Glass powder can be prepared by methods well known in the art.
• the glass component can be prepared by mixing and melting raw materials such as oxides, hydroxides, carbonates etc, making the product into a cullet by quenching, followed by mechanical pulverization (wet or dry milling). There after, if needed, classification is carried out to the desired particle size.
• the specific surface area of the glass powder is preferred to be no more than 10 m 2 /g. At least 90 wt% of the glass powder is preferred to have a particle diameter of 0.4 to 10 ⁇ m.
• the glass powder content is preferred to be 10 wt% to 50 wt%, based on the total amount of the composition. A proportion of glass powder within this range will ensure bonding with the adjacent PDP constituents, thereby ensuring the formation of sufficiently strong black bus electrodes.
• (C) Organic Binder An organic binder is used to allow constituents such as the conductive powder, glass powder, and black pigment to be dispersed in the composition. The organic binder is burned off.
• composition of the invention When the composition of the invention is used to produce a photosensitive composition, the development in an aqueous system is preferred to be taken into consideration in selecting the organic binder.
• One with high resolution is preferred to be selected.
• Examples of useful organic binders include copolymers or interpolymers prepared from (1 ) non-acidic comonomers containing Ci to Cio alkyl acrylates, Ci to Cio alkyl methacrylates, styrene, substituted styrene, or combinations thereof, and (2) acidic comonomers containing ethylenic unsaturated carboxylic acid-containing components.
• acidic comonomers When acidic comonomers are present in the electrode paste, the acidic functional groups will permit development in aqueous bases such as 0.8% sodium carbonate aqueous solution.
• the acidic comonomer content is preferred to be 15 wt% to 30 wt%, based on the polymer weight.
• a lower amount of acidic comonomer may complicate the development of the applied electrode paste, on account of aqueous bases, while too much acidic comonomer may reduce stability of the paste under a development condition, thereby resulting in only partial development in the areas where images are to be formed.
• Suitable acidic comonomers include (1 ) ethylenic unsaturated monocarboxylic acids such as acrylic acid, methacrylic acid, or crotonic acid; (2) ethylenic unsaturated dicarboxylic acids such as fumaric acid, itaconic acid, citraconic acid, vinylsuccinic acid, and maleic acid; (3) hemiesters of (1 ) and (2); and (4) anhydrides of (1 ) and (2). Two or more kinds of acidic comonomers may be used concurrently. Methacrylic polymers are more desirable than acrylic polymers in consideration of the combustibility in low-oxygen atmospheres.
• the non-acidic comonomer is an alkyl acrylate or alkyl methacrylate noted above, the non-acidic comonomer is preferred to be 70 wt% to 75 wt%, based on the polymer weight.
• the non-acidic comonomer is styrene or substituted styrene, the non-acidic comonomer is preferred to account for about 50 wt%, based on the polymer weight, and the remaining 50 wt% is preferred to be an acid anhydride such as a hemiester of maleic anhydride, ⁇ -methylstyrene is a preferred substituted styrene.
• the organic binder can be produced using techniques that are well known in the field of polymers. For example, an acidic comonomer can be mixed with one or more copolymerizable non-acidic comonomers in an organic solvent having a relatively low boiling point (75 to 15O 0 C) to obtain a 10 to 60% monomer mixture. Polymerization is then brought about by adding a polymerization catalyst to the resulting monomer. The resulting mixture is heated to the reflux temperature of the solvent. When the polymer reaction is substantially completed, the resulting polymer solution is cooled to room temperature to recover a sample.
• an acidic comonomer can be mixed with one or more copolymerizable non-acidic comonomers in an organic solvent having a relatively low boiling point (75 to 15O 0 C) to obtain a 10 to 60% monomer mixture. Polymerization is then brought about by adding a polymerization catalyst to the resulting monomer. The resulting mixture is heated to the reflux temperature of the solvent. When the polymer reaction is substantially completed
• the molecular weight of the organic binder is not particularly limited, but is preferably less than 50,000, more preferably less than 25,000, and even more preferably less than 15,000.
• the Tg (glass transition temperature) of the organic binder is preferred to be over 9O 0 C. Binders with a Tg below that temperature generally result in a highly adhesive paste when the electrode paste is dried at the usual temperature of 9O 0 C or below after screen printing. A lower glass transition temperature can be used for materials that are applied by means other than screen printing.
• the organic binder content is preferred to be 5 to 25 wt%, based on the total amount of the composition.
• the primary purpose for using an organic solvent is to allow the dispersion of solids contained in the composition to be readily applied to the substrate.
• the organic solvent is preferred to first of all be one that allows the solids to be dispersed while maintaining suitable stability.
• the rheological properties of the organic solvent are preferred to endow the dispersion with favorable application properties.
• the organic solvent may be a single component or a mixture of organic solvents.
• the organic solvent that is selected is preferred to be one in which the polymer and other organic components can be completely dissolved.
• the organic solvent that is selected is preferred to be inert to the other ingredients in the composition.
• the organic solvent is preferred to have sufficiently high volatility, and is preferred to be able to evaporate off from the dispersion even when applied at a relatively low temperature in the atmosphere.
• the solvent is preferred not to be so volatile that the paste on the screen will rapidly dry at ordinary temperature during the printing process.
• the boiling point of the organic solvent at ordinary pressure is preferred to be no more than 300 0 C, and preferably no more than 25O 0 C.
• organic solvents include aliphatic alcohols and esters of those alcohols such as acetate esters or propionate esters; terpenes such as turpentine, ⁇ - or ⁇ -terpineol, or mixtures thereof; ethylene glycol or esters of ethylene glycol such as ethylene glycol monobutyl ether or butyl cellosolve acetate; butyl carbitol or esters of carbitol such as butyl carbitol acetate and carbitol acetate; and Texanol (2,2,4-trimethyl-1 ,3-pentanediol monoisobutyrate).
• the organic solvent content is preferred to be 10 to 40 wt%, based on the total amount of the composition.
• Black pigment is used to ensure the blackness of the black bus electrode.
• the black pigment of the electrode paste in the present invention is not particularly limited. Examples include Co 3 O 4 , chromium-copper-cobalt oxides, chromium-copper-manganese oxides, chromium-iron-cobalt oxides, ruthenium oxides, ruthenium pyochlore, lanthanum oxides (ex. Lai- x Sr x Co ⁇ 3), manganese cobalt oxides, and vanadium oxides (ex. V2O3,
• Co 3 O 4 (thcobalt tetroxide) is preferred in consideration of the burden imposed on the environment, material costs, the degree of blackness, and the electrical properties of the black bus electrode. Two or more types may be used.
• the black pigment content is preferred to be 6 to 20 wt%, and preferably 9 to 16 wt%, based on the total amount of the composition.
• the conductive composition of the invention may contain the following optional components in addition to the above components.
• microelectrodes When forming microelectrodes, patterns are preferred to be formed using a photosensitive composition.
• Photopolymehzation Initiator Desirable photoinitiators will be thermally inactive but produce free radicals when exposed to actinic rays at a temperature of 185 0 C or below. Examples include compounds having two intramolecular rings in a conjugated carbocyclic system. More specific examples of desirable photoinitiators include 9,10-anthraquinone, 2-methyl anthraquinone, 2- ethyl anthraquinone, 2-t-butyl anthraquinone, octamethyl anthraquinone,
• the photoinitiator content is preferred to be 0.02 to 16 wt%, based on the total amount of the composition.
• Photopolymerizable monomers are not particularly limited. Examples include ethylenic unsaturated compounds having at least one polymerizable ethylene group.
• Such compounds can initiate polymer formation through the presence of free radicals, bringing about chain extension and addition polymerization.
• the monomer compounds are non-gaseous; that is, they have a boiling point higher than 100 0 C and have the effect of making the organic binder plastic.
• Desirable monomers that can be used alone or in combination with other monomers include t-butyl (meth)acrylate, 1 ,5-pentanediole di(meth)acrylate, N,N-dimethylaminoethyl (meth)acrylate, ethylene glycol di(meth)acrylate, 1 ,4-butanediol di(meth)acrylate, diethylene glycol di(meth)acrylate, hexamethylene glycol di(meth)acrylate, 1 ,3-propanediol di(meth)acrylate, decamethylene glycol di(meth)acrylate, 1 ,4- cyclohexanediol di(meth)acrylate, 2,2-dimethylol propane di(meth)acrylate, glycerol di(meth)acrylate, tripropylene glycol di(meth)acrylate, glycerol tri(meth)acrylate, thmethylol propane tri(me
• the content of the photopolymerizable monomer is preferred to be 2 to 20 wt%.
• a second embodiment of the invention relates to a front panel of a plasma display panel on which bus electrodes have been formed, wherein the bus electrode has a black-and-white double-layered structure comprising a black electrode and a white electrode, and the black electrode comprises silver-palladium alloy as a conductive component.
• the PDP of the invention is preferably an AC plasma display panel (AC PDP).
• Fig. 1 illustrates the structure of an AC PDP device with bus electrodes having a two-layer structure.
• the front panel of the AC PDP has the following structural elements: glass substrate 5, transparent electrodes 1 formed on the glass substrate 5, black bus electrodes 10 formed on the transparent electrodes 1 , and white electrodes 7 formed on the black bus electrodes 10.
• a dielectric coating layer (transparency overglaze layer) (TOG) 8 and an MgO coating layer 11 are generally formed on the white electrodes 7.
• the conductive composition of the invention is used to produce the black bus electrodes 10.
• the rear panel of the AC PDP has the following structural elements: a dielectric substrate 6, discharge spaces 3 filled with ionized gas, second 5 electrodes (address electrodes ) 2 parallel to the transparent electrodes 1 , and barrier walls 4 dividing the discharge spaces.
• the transparent electrodes 1 and second electrodes 2 face each other on either side of the discharge spaces 3.
• the black bus electrodes 10 and white electrodes 7 are formed in0 the following manner. First, a certain pattern is formed through exposure to light. The polymerization reaction will progress in the parts that have been exposed to light, altering the solubility to the developer. The pattern is developed in basic aqueous solution, and the organic parts are then eliminated through sintering at elevated temperature, whereas the 5 inorganic substances are sintered. The black bus electrodes 10 and white electrodes 7 are patterned using the same or very different images. Finally, an electrode assembly comprising sintered, highly conductive black bus electrodes 10 and white electrodes 7 is obtained. The electrode assembly looks black on the surface of the transparent o electrodes 1 , and the reflection of outside light is suppressed when placed on the front glass substrate. Although illustrated in Fig. 1 , the transparent electrodes 1 described below are not necessary when forming the plasma display device of the invention.
• a method for producing the bus electrodes on the front panel of the 5 PDP is described in detail below.
• the method for forming the first embodiment of the bus electrode of the invention comprises a series of processes (Figs. 2A through 2E).
• the transparent electrodes 1 are formed on the glass substrate 5 0 using SnO 2 or ITO in accordance with conventional methods known to those having ordinary skill in the art.
• the transparent electrodes are usually formed with SnO 2 or ITO. They can be formed by ion sputtering, ion plating, chemical vapor deposition, or an electrodeposition technique. Such transparent electrode structures and forming methods are well known in the field of AC PDP technology.
• the conductive composition for black bus electrodes in the invention is then used to apply an electrode paste layer 10, and the black electrode paste layer 10 is then dried in nitrogen or the air (Fig. 2A).
• a photosensitive thick film conductor paste 7 for forming the white electrodes is then applied on the black electrode paste layer 10.
• the white electrode paste layer 7 is then dried in nitrogen or the air (Fig. 2B).
• the white electrode paste used in the invention can be a well known or commercially available photosensitive thick film conductor paste.
• Desirable pastes for use in the invention may contain silver particles, glass powder, photoinitiators, monomers, organic binders, and organic solvents.
• the silver particle configuration may be random or thin flakes, preferably with a particle diameter of 0.3 to 10 ⁇ m.
• the glass powder, photoinitiator, monomer, organic binder, and organic solvent components can be of the same material as those used in the composition for the black bus electrodes. However, the amounts of the components will differ considerably.
• the amount in which the conductive silver particles are blended in particular will be greater in the white electrode paste, such as about 50 to 90 wt%, based on the total weight of the paste.
• the material is usually exposed to UV rays through a target 13 or photo tool having a configuration corresponding to the pattern of the black bus electrodes and white electrodes (Fig. 2C).
• the parts (10a, 7a) of the black electrode paste layer 10 and white electrode paste layer 7 that have been exposed to light are developed in a basic aqueous solution such as 0.4 wt% sodium carbonate aqueous solution or another alkaline aqueous solution.
• a basic aqueous solution such as 0.4 wt% sodium carbonate aqueous solution or another alkaline aqueous solution.
• the parts (10b, 7b) of the layers 10 and 7 that have not been exposed to light are removed.
• the parts 10a and 7a that have been exposed to light remain (Fig. 2D).
• the patterns after development are then formed.
• the material that has been formed is sintered at a temperature of 450 to 65O 0 C (Fig. 2E). At this stage, the glass powder melts and becomes firmly attached to the substrate.
• the sintering temperature is selected according to the substrate material.
• a precious metal-containing alloy is used as the conductive component of the black bus electrodes, and sintering can be done at about 600 0 C. As noted above, the reason is to ensure vertical conduction in PDP black bus electrodes. Sintering at lower temperature is also preferred because sintering at elevated temperatures tends to result in greater Ag diffusion.
• the front panel glass substrate assembly produced by the method in Fig. 2 can be used in AC PDP. Returning to Fig.
• the front glass substrate assembly is coated with a dielectric layer 8 and then an MgO layer 11.
• the front panel glass substrate 5 is then combined with a rear panel glass substrate 6.
• the conductive composition of the present invention can also be used to form black stripes in a PDP. Attempts to form the black stripes and black bus electrodes with the same composition have been proposed in order to simplify the manufacturing process (such as Japanese Laid- Open Patent Application 2004-063247), and the conductive composition of the invention can be employed in such a process.
• Texanol (2,2,4-thmethyl-1 ,3-pentanediol monoisobutyrate) as the organic solvent and an acrylic polymer binder having a molecular weight of 6,000 to 7,000 as the organic binder were mixed, and the mixture was heated to 100 0 C while stirred. The mixture was heated and stirred until all of the organic binder had dissolved. The resulting solution was cooled to 75 0 C.
• the black electrode paste was applied to a glass substrate by screen printing using a 200 to 400 mesh screen. Suitable screen and viscosity of the black electrode paste was selected, to ensure the desired film thickness was obtained.
• the paste was applied on a glass substrate on which transparent electrodes (thin film ITO) had been formed.
• the paste was then dried for 20 minutes at 100 0 C in a hot air circulating furnace, so as to form black bus electrodes having a dried film thickness of 4.5 to 5.0 ⁇ m.
• the white electrode paste was applied by screen printing using a 400 mesh screen so as to cover the black electrodes. This was again dried for 20 minutes at 100 0 C. The thickness of the dried double-layered structure was 12.5 to 15 ⁇ m.
• the double-layered structure was exposed to light through a photo tool using a collimated UV radiation source (illumination: 18 to 20 mW/cm 2 ; exposure: 200 mj/cm 2 ).
• a peak temperature of 59O 0 C was reached (first sintering) by sintering in a belt furnace in air using a 1.5 hour profile.
• TOG Coating TOG paste was then screen printed using a 150 stainless steel mesh screen. This was again dried for 20 minutes at 100 0 C. Sintering (second sintering) was done at a peak temperature of 58O 0 C in a belt furnace in air using a 2.0 hour profile.
• the degree of blackness as viewed from the rear panel of the glass substrate was determined.
• colors (L * , a * , b * ) were determined using a device by Nippon Denshoku. A standard white plate was used for calibration at this time.
• L * indicates the brightness
• a * indicates red and green
• b * indicates yellow and blue.
• An L * of 100 indicates pure white, and 0 indicates pure black. The higher the numerical value of a * , the redder the color. The higher the numerical value of b * , the yellower the color.

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