FR2819628A1 - Back tile structure for a plasma visual display screen incorporating a dielectric layer of a porous oxide material to reduce the number of firing operations during fabrication - Google Patents

Abstract

A back tile structure for a plasma visual display screen has a substrate carrying a network of electric conducting electrodes, a dielectric layer, a network of barriers and a network of red, green and blue luminphores arranged between the barriers. A back tile structure for a plasma visual display screen has a substrate carrying a network of electric conducting electrodes, a dielectric layer, a network of barriers and a network of red, green and blue luminphores arranged between the barriers. The dielectric layer is made of a porous material composite of a powder with a granulometry of 0.4-10 microns or of an aerogel or of a mixture of the two with a thickness of 3-30 microns. The composition of the porous material is an oxide or mixture of oxides or solution of oxides. The oxides are chosen from those of silicon, aluminium, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkaline oxides, glasses of borosilicate or borophosphosilicate. Independent claims are also included for the fabrication of such a back tile and for a plasma visual display screen incorporating such a back tile.

Description

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Plasma panel type display devices use the principle of an electroluminescent discharge in a gas to produce UV rays which are then converted into visible light by phosphors. The manufacturing process for these plasma screens is made up of many stages, essentially including deposition, etching and cooking operations. The cost of these operations is high in particular due to the large number of firings at more than 450oc.

deux cycles thermiques entre 520 et 600oC. Une couche d'oxyde de magnésium est ensuite déposée sur la surface du diélectrique cuit. The structure of these plasma panels consists of a front panel on which one or more networks of electrodes are deposited, in general a network of transparent electrodes lined with so-called bus electrodes which serve to reduce the line resistance of the transparent electrodes and which are often silver and baked at around 550oC. These electrodes are then covered with a dielectric layer which is itself baked in one or

two thermal cycles between 520 and 600oC. A layer of magnesium oxide is then deposited on the surface of the baked dielectric.

un cycle thermique entre 520 et 600oc. On réalise ensuite un réseau de barrières dont la fonction est de séparer les colonnes de cellules de couleurs différentes et de maintenir un espacement constant entre les substrats avant et arrière dans le dispositif final. Ce réseau de barrières peut être réalisé par sérigraphie en plusieurs niveaux mais il est très souvent obtenu par dépôt d'une couche épaisse et continue d'un matériau tel qu'un verre à bas point de fusion, photolithographie d'un masque en résine sur cette couche puis sablage. The rear substrate carries a network of electrodes called data electrodes often made from a silver paste and which then undergo a first baking between 520 and 600oc. These electrodes can also be produced by photolithography of a thin layer. These electrodes are covered with a dielectric layer also baked in

a thermal cycle between 520 and 600oc. A network of barriers is then produced, the function of which is to separate the columns of cells of different colors and to maintain constant spacing between the front and rear substrates in the final device. This network of barriers can be produced by screen printing in several levels but it is very often obtained by depositing a thick and continuous layer of a material such as a glass with low melting point, photolithography of a resin mask on this layer then sanding.

520OC de manière à éliminer les composés organiques utilisés lors du dépôt des luminophores. Le procédé appliqué sur le substrat arrière contient donc souvent au moins trois cuissons à 520oC ou plus, ce qui a pour effet de distordre le substrat rendant incertaine la superposition des niveaux sur le substrat arrière puis la superposition du substrat avant et du substrat arrière. Ces cuissons multiples ont également un coût The purpose of the sandblasting operation is to remove the material from the thick layer between the patterns drawn by the resin. The resin is then removed during a step called stripping which consists in dissolving said resin in an aqueous solution or not. A cooking operation then has the effect of sintering and greatly densifying the material of the barriers. This cooking takes place between 520 and 580oc. The phosphors are then deposited in the channels formed by the barriers, then the substrate is baked between 450 and

520OC so as to eliminate the organic compounds used when depositing the phosphors. The process applied to the rear substrate therefore often contains at least three firing at 520 ° C. or more, which has the effect of distorting the substrate making it uncertain the superposition of the levels on the rear substrate then the superposition of the front substrate and the rear substrate. These multiple cookings also have a cost

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 high making the current process very expensive.

The present invention consists of a rear substrate structure for a plasma panel of the coplanar type. The structure object of this invention shown in Figure 1 consists of a glass substrate [1] on which is deposited an array of electrodes [2], this array then being covered by a dielectric layer [3] of a porous material d 'white diffusing appearance, the network of barriers [4] being carried by this dielectric layer, the top [5] of the barriers may be dark to increase the contrast of the panel, the phosphors [6] being deposited between the barriers. The sealing joint [7] intended to seal the front and rear substrates of the plasma screen can advantageously be deposited on this rear slab.

The glass substrate is made of soda-lime glass or special glass having a higher softening temperature as proposed by the manufacturers of flat glass. The thickness can vary from 1 to 6 millimeters, the typical value being 3 mm. The electrode array consists of parallel electrodes at least in the useful area of the screen. The network pitch depends on the resolution requested on the screen, the typical values being between 200 and 450 u. m. The pitch may not be constant, the distance between two electrodes may in particular depend on the colors corresponding to the electrodes. The width of the electrodes is between one third and two thirds of the pitch. The dielectric layer consists of a porous material composed of a powder with an average particle size between 0.4 and 10 μm or an airgel or a mixture of a powder with an average particle size between 0.4 and 10 μ. m and an airgel, the composition of this porous material being an oxide or mixture of oxides or solution of oxides among the oxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkaline oxides, borosilicate or borophosphosilicate glasses. This composition can be added with one or more glasses with a low melting point of lead silicate or borosilicate or bismuth in a mass fraction of less than 40%. The thickness of this layer can vary from 3 to 30 u. m. The body of the barriers consists of a porous material composed of a powder with an average particle size between 0.7 and 12 μm or an airgel or a mixture of a powder with an average particle size between 0.7 and 12 m and d '' an airgel, the composition of this porous material being an oxide or mixture of oxides or solution of oxides among the oxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium , lead, bismuth, alkaline oxides, borosilicate or borophosphosilicate glasses. This composition can

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 be added with one or more glasses with a low melting point of lead silicate or borosilicate or bismuth in mass fraction less than 40%. The height of the barriers can vary from 70 to 200! lm, a typical value being 110! lm. Their width is between 40 and 150 µm, a typical value being 80 µm, and may not be uniform over the height of the barriers. When the barriers have a dark layer at the top, the material constituting this layer is also porous. The composition of this porous material is chosen from the compositions described above for the body of the barriers, without necessarily being the same composition as that of the body of the barriers, and with a particle size between 0.7 and 6 p. m. This composition is however added, to obtain the dark shade, a complex oxide which is a mixture or a solution of oxides chosen from oxides of iron, cobalt, copper, chromium, aluminum and nickel. These compositions of black or dark blue oxides are known and widely marketed. An additional fraction of one or more glasses with a low melting point of lead silicate or borosilicate or bismuth can be added without, however, the total mass fraction of the composition being greater than 70%. The thickness of this layer can vary from 2 to 20 µm. Luminophores are the compounds conventionally used in plasma screens, for example yttrium oxide doped with europium for red, zinc silicate doped with manganese or mixed oxide of barium-aluminum magnesium doped with manganese for green, and mixed barium-aluminum magnesium oxide doped with europium for blue. They are deposited in a layer 10 to 30 μm thick on the dielectric layer between the barriers as well as on the sides of the barriers.

The advantage of such a structure is that it is very porous and therefore allows very easy degassing when pumping the panel before final filling.

granulométrie moyenne comprise entre 0. 3 et 3 ! lm. Le liant minéral est un verre dont la température de ramollissement est comprise entre 350oC et 450oC, par exemple un borosilicate de plomb, et dont la granulométrie moyenne est comprise entre 0.5 et 3 um. La proportion de liant minéral dans la poudre métallique est comprise entre 5% et 40%. La solution liquide est composée d'un solvant tel qu'un glycol (par exemple de l'éthylène glycol ou du propylène glycol ou du butylène glycol) ou un ester de glycol ou un The present invention also consists of a method for producing the structure described above. To make the electrodes according to the invention, a paste is prepared containing silver powder or silver-rich alloy, a mineral binder and a liquid solution containing a solvent added with a resin. Silver powder has a

average particle size between 0.3 and 3! lm. The mineral binder is a glass whose softening temperature is between 350 ° C. and 450 ° C., for example a lead borosilicate, and whose average particle size is between 0.5 and 3 μm. The proportion of mineral binder in the metal powder is between 5% and 40%. The liquid solution is composed of a solvent such as a glycol (for example ethylene glycol or propylene glycol or butylene glycol) or a glycol ester or a

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sérigraphie puis séchées entre 100 et 200oc. A ce point du procédé, aucune cuisson à plus de 300oC n'est pratiquée sur le substrat et ses électrodes. heavy alcohol or a heavy ketone or terpineol, the solvent being added with a resin such as cellulose, acrylic, etc. The solvent can also be water and the resin is then a PVA (alcohol polyvinyl) or PVP (polyvinylpyrrolidone). The amount of resin in the solvent is between 0.5 and 10%, typically 2% to 5%. The quantity of liquid solution is such that the viscosity is compatible with screen printing, that is to say between 5,000 and 100,000 centipoises. The electrodes are then deposited by

serigraphy then dried between 100 and 200oc. At this point in the process, no cooking at more than 300oC is carried out on the substrate and its electrodes.

However, the electrodes can also be produced by conventional technology, that is to say by depositing from a conventional silver paste, containing inorganic binders fusible at higher temperature than those mentioned above, then baking between 520 and 600oc. The electrodes can also be produced by photoetching of a metal layer deposited by sputtering, for example aluminum or a chromium-copper-chromium stack.

de granulométrie inférieure à 3 u. m d'un verre d'oxydes dont la température de ramollissement est inférieure à 450oC. La quantité de solution aqueuse dans la pâte est telle que la viscosité est compatible avec la technique de dépôt, c'est-à-dire entre 5000 et 100 000 centipoises si la pâte est déposée par sérigraphie, moins de 4000 centipoises si la pâte est déposée en spray. D'autres techniques de dépôt sont cependant utilisables To produce the dielectric layer according to the invention, a paste is prepared from an aqueous solution of a polyvinyl alcohol with a mass concentration of between 3 and 20%, an aqueous solution optionally added with anti-foaming agents or agent. texture, for example glycols such as triethylene glycol, this paste also containing an oxide or a mixture of oxides or solution of oxides among the oxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium , cerium, tin, vanadium, lead, bismuth, alkaline oxides, borosilicate or borophosphosilicate glasses, with a particle size between 0.4 and 10 am. This paste is optionally added with a binding agent in the form of a colloidal solution of an oxide or a hydroxide chosen from oxides and hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium. , cerium, tin, vanadium, lead, bismuth, alkali oxides or a binding agent in the form of an oxide or hydroxide airgel chosen from oxides and hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkali oxides or a binder in powder form

particle size less than 3 u. m of a glass of oxides with a softening temperature below 450oC. The quantity of aqueous solution in the dough is such that the viscosity is compatible with the deposition technique, that is to say between 5000 and 100,000 centipoises if the dough is deposited by screen printing, less than 4000 centipoises if the dough is deposited in spray. Other deposition techniques can however be used

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sans limiter le champ d'application de l'invention. On procède ensuite au séchage entre 50 C et 200oc. L'épaisseur de cette couche après séchage peut varier de 3 à 30 um. La concentration élevée de résine dans le dépôt après séchage qui provient de la forte concentration de résine dans la solution décrite ci-dessus, ainsi que la présence de plastifiants et la polymérisation forte de la résine permettent à la couche de n'être que très peu sensible à l'opération de sablage ultérieure pour former le motif des barrières.

without limiting the scope of the invention. The drying is then carried out between 50 ° C. and 200 ° C. The thickness of this layer after drying can vary from 3 to 30 μm. The high concentration of resin in the deposit after drying which comes from the high concentration of resin in the solution described above, as well as the presence of plasticizers and the strong polymerization of the resin allow the layer to be very little sensitive to the subsequent sanding operation to form the barrier pattern.

The barriers are then created. We proceed in three or four stages. First of all, a layer is deposited which will form the body of the barriers, that is to say most of the height of the barriers. If the structure incorporates a dark layer at the top of the barriers, then deposit a thinner layer which will constitute the top of the barriers. In a third step, the mask is produced by photolithography which will serve to delimit the pattern of the barriers. Finally, the layers deposited and not protected by the mask are abraded by sandblasting. The advantage of the process of the invention is that it does not require the removal of the mask necessary for sandblasting because it is destroyed during the final heat treatment.

To make the layer which will form the body of the barriers according to the invention, a paste is prepared from an aqueous solution of a polyvinyl alcohol with a mass concentration of between 0.5 and 8%, an aqueous solution optionally added with anti-foaming agents or texture agent, for example glycols such as triethylene glycol, this paste also containing an oxide or a mixture of oxides or solution of oxides among the oxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkaline oxides, borosilicate or borophosphosilicate glasses, with a particle size between 0.7 and 12 lam. This paste is optionally added with a binding agent in the form of a colloidal solution of an oxide or a hydroxide chosen from oxides and hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium , cerium, tin, vanadium, lead, bismuth, alkaline oxides or a binding agent in the form of an oxide airgel chosen from oxides and hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkaline oxides or a binding agent in the form of a powder with a particle size less than 3 µm from a glass of oxides whose softening temperature is less than 450oC. The amount of aqueous solution is such that the viscosity is compatible with the deposition technique, that is to say between 5,000 and 100,000 centipoises if the paste is deposited by screen printing. Other deposition techniques can however be used without limiting the scope of the invention. We proceed

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ensuite au séchage entre 50 C et 200oC. L'épaisseur de cette couche sèche peut varier de 70 à 200 gm. La faible concentration de résine dans le dépôt après séchage, qui provient de la faible concentration de résine dans la solution décrite ci-dessus, permet à la couche d'être très sensible à l'opération de sablage ultérieure pour former le motif des barrières.

then drying between 50 C and 200oC. The thickness of this dry layer can vary from 70 to 200 gm. The low concentration of resin in the deposit after drying, which comes from the low concentration of resin in the solution described above, allows the layer to be very sensitive to the subsequent sanding operation to form the pattern of the barriers.

l'invention. On procède ensuite au séchage entre 50 C et 200oC. L'épaisseur de cette couche sèche peut varier de 2 à 20 u. m. De même que pour la couche destinée à former le corps des barrières et décrite précédemment, la faible concentration de résine dans le dépôt après séchage, qui provient de la faible concentration de résine dans la solution décrite cidessus, permet à la couche d'être très sensible à l'opération de sablage ultérieure pour former le motif des barrières. To produce, when it is present in the structure, the top layer of the barriers according to the invention, a paste is prepared containing an oxide or a mixture of oxides or solution of oxides of composition among the compositions mentioned above for the production of the body paste from the barriers. This paste is added with a granolumetric powder of between 0.7 and 6 μm of a mixture or solution of oxides chosen from the oxides of iron, cobalt, copper, chromium, aluminum and nickel. This paste can also be added with an additional fraction of glasses of silicate or borosilicate of lead or bismuth without however that the total mass fraction of glassy material in the paste exceeds 70%. The amount of aqueous solution is such that the viscosity is compatible with the deposition technique, that is to say between 5,000 and 100,000 centipoises if the paste is deposited by screen printing. Other deposition techniques can however be used without limiting the scope of

the invention. The drying is then carried out between 50 ° C. and 200 ° C. The thickness of this dry layer can vary from 2 to 20 μm. As for the layer intended to form the body of the barriers and described above, the low concentration of resin in the deposit after drying, which comes from the low concentration of resin. in the solution described above, allows the layer to be very sensitive to the subsequent sanding operation to form the pattern of the barriers.

The third step in producing the barriers according to the invention consists in making a mask which will have the function of blocking the erosion of the underlying layers by the jet of particles in the sandblasting operation.

According to the invention, this mask is produced by depositing a layer of photosensitive resin.

This resin may be weakly loaded with a mineral material.

In the case where the resin is not loaded with a mineral material, the liquid solution is an aqueous solution of a polyvinyl alcohol (PVA) the grade of which can be chosen from a very wide range and a photosensitizer. The amount of PVA in the solvent is between 6 and 25%. For the photosensitizer, it may be ammonium, sodium or potassium dichromate or else diazotized compounds known to cause the polymerization of PVA under exposure to ultraviolet rays. The concentration of the photosensitizer varies with the nature of the

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 photosensitizer. For bichromates, for example, the quantity of photosensitizer expressed as a percentage of a solution at 100 grams per liter of the dichromate considered is generally chosen between 1 to 10% by mass of the aqueous PVA solution. This solution is optionally supplemented with anti-foaming agents and texturing or plasticizing agents such as for example glycols such as triethylene glycol. The quantity of resin is such that the viscosity is compatible with the deposition technique, that is to say between 5,000 and 100,000 centipoises if the paste is deposited by screen printing. Other deposition techniques can however be used without limiting the scope of the invention.

In the case where the resin is loaded with a mineral material, a solution is prepared as before for a resin not loaded with the photosensitizer and the anti-foaming and texturing agents, then a mineral filler composed of a powder of smaller particle size is added. at 3 μm or a colloidal solution or an airgel, the composition of this mineral filler being an oxide or a hydroxide or mixture of oxides or hydroxides or solution of oxides or hydroxides among the oxides and hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkali oxides, this charge can also be composed of borosilicate or borophosphosilicate glasses or, in fraction mass by less than 40%, one or more glasses of oxides whose softening temperature is less than 450oC. The mass fraction of the mineral filler in the dough is between 0 and 20%. The amounts of resin and additives in the liquid solution are such that the viscosity is compatible with the deposition technique, that is to say between 5,000 and 100,000 centipoises if the paste is deposited by screen printing. Other deposition techniques can however be used without limiting the scope of the invention.

After the deposition, the drying is carried out between 40 ° C. and 100 ° C. The thickness of this dry layer can vary from 2 to 25 µm, a typical value being 9 µm. This layer consisting of a high proportion of resin intended to form the mask for sandblasting is very little sensitive to erosion during sandblasting.

The photolithography phases are shown diagrammatically in FIGS. 2a and 2b.

The substrate [1] supports the electrodes [2], the dielectric layer [3], as well as the barrier layers [8] and [9] intended to respectively form the body and the top of the barriers. The layer [10] intended to form the sandblasting mask is exposed to a flow of ultraviolet rays [11] (FIG. 2a) through an exposure mask [12]. The sunscreen mask contains the pattern of the barriers, the areas of the mask opaque to UV rays

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correspondant aux zones à graver car la résine à base de PVA est de type négatif Le flux UV nécessaire pour obtenir une polymérisation dépend fortement de l'épaisseur de résine et il est généralement compris entre 100 et 2000 mJ/cm2. On procède ensuite au développement de la résine. Cette opération consiste à dissoudre la résine dans les zones non insolées (figure 2b). Elle s'opère en projetant sur la surface de la couche un jet de gouttelettes d'eau. On sèche ensuite la surface. On procède alors au sablage pour former les barrières. Cette opération consiste à projeter sur la surface des grains de matériau comme par exemple du verre ou du sable ou du carbonate de sodium. Cette technologie de sablage est déjà utilisée pour former les barrières dans les écrans à plasma mais elle utilise comme masque de sablage une résine en film sec pour protéger de l'abrasion le matériau précurseur des barrières.

corresponding to the areas to be etched because the PVA-based resin is of the negative type. The UV flux required to obtain a polymerization strongly depends on the thickness of the resin and it is generally between 100 and 2000 mJ / cm2. Then proceed to the development of the resin. This operation consists in dissolving the resin in the non-exposed areas (Figure 2b). It is carried out by projecting onto the surface of the layer a jet of water droplets. The surface is then dried. Sandblasting is then used to form the barriers. This operation consists in projecting onto the surface grains of material such as for example glass or sand or sodium carbonate. This sandblasting technology is already used to form the barriers in plasma screens but it uses a dry film resin as a sanding mask to protect the precursor material of the barriers from abrasion.

The surface is then cleaned by blowing with pressurized air or by exposure to a stream of water or a spray of water and then drying.

We can then deposit the phosphors. For this, a paste is prepared containing a liquid solution of a resin and a powder of a red phosphor. The liquid resin solution is composed of an aqueous solution of a polyvinyl alcohol (PVA), the grade of which can be chosen from a very wide range. The amount of PVA in the solvent is between 3 and 20%, typically 6% to 15%. This solution is optionally supplemented with anti-foaming and texturing agents, for example glycols such as triethylene glycol. The red phosphor is a yttrium oxide doped with europium whose average particle size is between 0.8 and 5 lam.

The amount of liquid solution in the dough is such that the viscosity is compatible with the deposition technique, that is to say between 5000 and 100,000 centipoises if the dough is deposited by screen printing. This red phosphor is deposited in a network of bands parallel to the barriers, the width of which is approximately equal to the pitch of the network of barriers, and the pitch of which is three times that of the network of barriers. Other deposition techniques can however be used without limiting the scope of the invention.

The drying is then carried out between 40 ° C. and 200 ° C. The quantity of paste deposited is such that the covering of the dielectric between the barriers and of the sides of the barriers is complete. The typical thickness of the layer on the dielectric, in the center of the strip between the barriers is between 10 and 25 pu.

The procedure is then carried out in the same way for the deposition of the green and blue phosphors and so as to form a pattern composed of three bands, red, green and blue, this pattern being repeated over the entire width of the substrate covered by the network of barriers. The

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 Green phosphor is either a complex barium, aluminum and magnesium oxide doped with manganese, or a zinc silicate doped with manganese. The blue phosphor is a complex barium, aluminum and magnesium oxide doped with europium.

The order in which the colors are deposited can be alternated and the chemical nature of the phosphor materials modified without limiting the scope of the invention.

On this rear slab, it is advantageous to deposit the bead of sealing material. This bead can be deposited by extrusion through an orifice of a paste containing a solvent, a resin and a glass frit. The glass forming the frit will be a glass with a low melting point of which there are commercially numerous references suitable for the sealing of glass slabs. This glass will however be a non-crystallizable (or non-devitrifiable) type glass. This cord is then dried between 50 and 200oc.

réalisée. Comme la résine utilisée tout au long du procédé est du PVA, à l'exception peut- être des électrodes, on peut cuire le substrat arrière à une température comprise entre 400 et 480oC, pendant une durée allant de 10 minutes à plusieurs heures, un cycle typique étant 450oC pendant 30 minutes. The completion of the rear slab is completed by baking the entire structure

performed. As the resin used throughout the process is PVA, with the possible exception of electrodes, the back substrate can be baked at a temperature between 400 and 480oC, for a period ranging from 10 minutes to several hours, a typical cycle being 450oC for 30 minutes.

In an improvement of the process of the invention, the layer which serves as a mask during the sandblasting operation produces the black layer at the top of the barriers. It is then not necessary to previously deposit the black layer at the top of the barriers. The paste which is used to produce the mask is identical to that described above for the production of the sandblasting mask, possibly with its mineral filler as described above, but it is additionally charged with a black powder oxide. The oxide is a mixture or solution of oxides chosen from iron, cobalt, copper, chromium, aluminum and nickel oxides. The average particle size of this powder is between 0.7 and 3! lm.

The advantages of this process are manifold. A first advantage is that this process contains only one final baking between 400 and 520oC. The cost of producing this structure is therefore very low compared to the cost of current methods. In addition, no deformation of the glass substrate occurs during the process and the alignment of the barriers on the electrodes then depends only on the quality of the exposure masks. Alignments better than 20 ju. m over the entire surface of the substrate are thus easy to obtain. A second advantage is that the development of the masking resin (PVA) takes place with water, therefore without the addition of a chemical which requires reprocessing of the water. A third advantage lies in the very strong adhesion of the masking layer on the

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 underlying layers because the same resin is used in the layers forming the barriers and the layer forming the mask. A fourth advantage is that the masking layer for the sanding operation does not need to be stripped because the resin which constitutes it is thermally decomposed during the final baking between 400oC and 480oC.

A fifth advantage is that this same layer can also act as a dark layer at the top of barriers. A sixth advantage is that the production cost is very reduced since only one cooking is necessary. A seventh advantage is that this structure can be produced without any heavy metal such as lead or bismuth.

The present invention also consists of a plasma display screen using, in part or totally, the structure described above, and at least the structure of the dielectric layer made of a very porous material.

A first example of embodiment of a rear panel is described below. The soda-lime glass substrate is 1000 mm long and 560 mm wide. The rear panel must have 2880 column electrodes with a 0.32 mm pitch.

The electrodes are produced by screen printing with a silver paste. This silver paste is prepared by mixing 100 grams of an aqueous solution of polyvinyl alcohol of grade 30/70 to 1000 centipoise, 400 grams of silver powder of average particle size 0.8 μm, 20 grams of a solution aqueous colloidal silica with 30% silica and 5 grams of a WLN reference commercial antifoam. The solution is homogenized by agitation with ultrasound. The deposition of this paste is carried out by screen printing through a stainless steel fabric of 140 mesh per centimeter. The canvas is blocked by a resin with the exception of the zones corresponding to the electrodes and to the edge connectors of the slab, that is to say strips of width 150 film. The dough deposited is then dried in a hot air oven at 120OC for 15 minutes. The paste intended for the production of the dielectric layer is then prepared. For this, 120 grams of an aqueous solution of polyvinyl alcohol of grade 30/70 to 1000 centipoise, 150 grams of silica powder with an average particle size of 2 μm, 50 grams of titanium oxide with an average particle size of 0.5 μm are mixed, 40 grams of an aqueous solution of colloidal silica containing 30% of silica and 5 grams of a commercial anti-foam agent of WLN reference. The solution is homogenized by passage through a sorter. The deposition of this paste is carried out by screen printing through a stainless steel cloth of 54 mesh per centimeter over the entire surface of the slab with the exception of a strip of 5 millimeters over the two widths of the substrate and a strip of width 18 millimeters over the two lengths of the substrate, the lengths corresponding to the position of the connectors. The deposited dough is then dried

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dans un four à air chaud à 200oC pendant 15 minutes. L'épaisseur de la couche sèche est de 15 J. m. On réalise ensuite la première couche destinée à former le corps des barrières. Pour cela, on mélange 100 grammes d'une solution aqueuse d'alcool polyvinylique de grade 14/135 à 200 centipoises, 200 grammes de poudre d'alumine de granulométrie moyenne 4 jum, 20 grammes d'oxyde de titane de granulométrie moyenne 0.5 Ilm, 20 grammes d'une solution aqueuse de silice colloïdale à 30% de silice et 5 grammes d'un anti-mousse commercial de référence WLN. La solution est homogénéisée par passage dans un tribroyeur. Le dépôt de cette pâte est réalisé par sérigraphie à travers une toile polyester de 34 mailles au centimètre sur toute la surface de la dalle de la couche diélectrique déposée précédemment. On sèche ensuite la pâte déposée dans un four à air

chaud à 60 C pendant 10 minutes. On procède à trois dépôts successifs avec un séchage intermédiaire pour obtenir une épaisseur totale de 105 Ilm pour la couche sèche. On réalise ensuite la deuxième couche, destinée à former le sommet des barrières. Pour cela, , on mélange 100 grammes d'une solution aqueuse d'alcool polyvinylique de grade 14/135 à 200 centipoises, 100 grammes de poudre d'alumine de granulométrie moyenne 4 Ilm, 120 grammes d'oxyde mixte de cobalt, cuivre et chrome et aluminium, 20 grammes d'une solution aqueuse de silice colloïdale à 30% de silice et 5 grammes d'un anti-mousse commercial de référence WLN. La solution est homogénéisée par passage dans un tribroyeur. Le dépôt de cette pâte est réalisé par sérigraphie à travers une toile polyester de 90 mailles au centimètre sur toute la surface de la dalle de la première couche des barrières

déposée précédemment. On sèche ensuite la pâte déposée dans un four à air chaud à 60 C pendant 5 minutes. L'épaisseur de cette couche sèche est de 10 nm. On réalise alors la couche de masquage pour le sablage. On prépare pour cela une solution avec 100 grammes de PVA de grade 30/70 à 2000 centipoises, solution additionnée de 8 grammes d'une solution à 100 grammes par litre de bichromate de sodium, 5 grammes de triéthylène glycol, de 2 grammes de glycérol et de 3 grammes d'anti-mousse de référence commerciale WLN. La solution est homogénéisée par agitation avec des ultra-sons. Le dépôt de cette pâte est réalisé par sérigraphie à travers une toile polyester de 77 mailles au centimètre sur toute la surface de la dalle des couches des barrières déposées précédemment. On sèche ensuite la pâte déposée dans un four à air chaud à 60 C pendant 4 minutes. L'épaisseur de cette couche sèche est de 6 um. On expose alors cette couche de résine à un flux de 800 mJ/cm de rayons ultra-violet de longueur d'onde 365 nm à travers un masque dont les zones sombres forment des colonnes de largeur 70 um au pas de 0.32 mm et qui correspondent à l'emplacement des futures barrières. On développe cette

in a hot air oven at 200oC for 15 minutes. The thickness of the dry layer is 15 J. m. The first layer is then made to form the body of the barriers. For this, 100 grams of an aqueous solution of polyvinyl alcohol of grade 14/135 are mixed with 200 centipoises, 200 grams of alumina powder with a mean particle size of 4 μm, 20 grams of titanium oxide with a mean particle size of 0.5 μm. , 20 grams of an aqueous solution of colloidal silica containing 30% of silica and 5 grams of a commercial anti-foam agent of WLN reference. The solution is homogenized by passage through a sorter. The deposition of this paste is carried out by screen printing through a polyester fabric of 34 meshes per centimeter over the entire surface of the slab of the dielectric layer previously deposited. The dough deposited is then dried in an air oven

hot at 60 C for 10 minutes. Three successive deposits are made with intermediate drying to obtain a total thickness of 105 μm for the dry layer. The second layer is then produced, intended to form the top of the barriers. For this, 100 grams of an aqueous solution of polyvinyl alcohol of grade 14/135 are mixed with 200 centipoise, 100 grams of alumina powder with a mean particle size of 4 Ilm, 120 grams of mixed oxide of cobalt, copper and chromium and aluminum, 20 grams of an aqueous solution of colloidal silica containing 30% of silica and 5 grams of a commercial anti-foam agent of WLN reference. The solution is homogenized by passage through a sorter. The deposition of this paste is carried out by screen printing through a polyester fabric of 90 mesh per centimeter over the entire surface of the slab of the first layer of the barriers.

previously filed. The dough deposited is then dried in a hot air oven at 60 C for 5 minutes. The thickness of this dry layer is 10 nm. The masking layer is then produced for sandblasting. A solution is prepared for this with 100 grams of PVA of grade 30/70 to 2000 centipoise, solution added with 8 grams of a solution at 100 grams per liter of sodium dichromate, 5 grams of triethylene glycol, of 2 grams of glycerol and 3 grams of WLN commercial reference defoamer. The solution is homogenized by shaking with ultrasound. The deposition of this paste is carried out by screen printing through a polyester fabric of 77 mesh per centimeter over the entire surface of the slab of the layers of the barriers deposited previously. The dough deposited is then dried in a hot air oven at 60 C for 4 minutes. The thickness of this dry layer is 6 µm. This layer of resin is then exposed to a flow of 800 mJ / cm of ultraviolet rays of wavelength 365 nm through a mask, the dark areas of which form columns of width 70 μm in steps of 0.32 mm and which correspond at the location of future barriers. We are developing this

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couche à l'eau en l'exposant 30 secondes à un jet de gouttelettes d'eau à 30oC. On sèche ensuite la surface en portant le substrat à 60 C pendant 10 minutes puis on procède au sablage avec une poudre de carbonate de sodium. On procède ensuite à un nettoyage de la surface par soufflage avec de l'air sous pression. On dépose enfin les luminophores selon un réseau de bandes au pas de 0.96 mm. On prépare pour cela une solution avec 100 grammes de PVA de grade 30/70 à 400 centipoises, 160 grammes d'une poudre de luminophore rouge d'oxyde d'yttrium dopé europium de granulométrie moyenne 2.5 ! lm, 2 grammes d'un tensio-actif de référence commerciale OROTAN 850 et de 5 grammes d'anti-mousse de référence commerciale WLN. La solution est homogénéisée par passage dans un tribroyeur. Le dépôt de cette pâte est réalisé par sérigraphie à travers une toile polyester de 54 mailles au centimètre sur toute la surface de la dalle des couches des barrières déposées précédemment. La toile est bouchée par une résine à l'exception de zones de largeur 0.30 mm au pas de 0.96 mm et correspondant aux bandes du luminophore rouge. On sèche ensuite la pâte déposée dans un four à air chaud à 100oC pendant 5 minutes. On procède de même pour le dépôt du luminophore vert de silicate de zinc de granulométrie moyenne 2 um et du luminophore bleu d'oxyde mixte de barium, aluminium et magnésium dopé à l'europium et de granulométrie moyenne 2 u. m. Sur cette dalle arrière, on dépose le cordon de matériau de scellement à l'aide d'un dispenseur à seringue. On prépare pour cela une solution avec 100 grammes de PVA de grade 14/135 à 200 centipoises, et 250 grammes d'une poudre de fritte de verre non cristallisable de référence commerciale LS0118 de granulométrie moyenne 80 film. Ce cordon est alors

séché à 100OC pendant 10 minutes. On termine la réalisation de la dalle arrière par la cuisson de l'ensemble de la structure réalisée à une température comprise de 480OC pendant 20 minutes. La dalle est alors prête pour être assemblée avec une dalle avant pour former un écran à plasma.

layer with water by exposing it for 30 seconds to a jet of water droplets at 30oC. The surface is then dried, bringing the substrate to 60 ° C. for 10 minutes, then sanding is carried out with a powder of sodium carbonate. The surface is then cleaned by blowing with pressurized air. Finally, the phosphors are deposited according to a network of bands with a pitch of 0.96 mm. For this, a solution is prepared with 100 grams of PVA of grade 30/70 to 400 centipoise, 160 grams of a powder of red phosphor of europium doped yttrium oxide of average particle size 2.5! lm, 2 grams of a commercial reference surfactant OROTAN 850 and 5 grams of commercial reference defoamer WLN. The solution is homogenized by passage through a sorter. The deposition of this paste is carried out by screen printing through a polyester fabric of 54 mesh per centimeter over the entire surface of the slab of the layers of the barriers deposited previously. The canvas is plugged with a resin, with the exception of zones 0.30 mm wide in steps of 0.96 mm and corresponding to the bands of the red phosphor. The dough deposited is then dried in a hot air oven at 100oC for 5 minutes. We proceed in the same way for the deposition of the green phosphor of zinc silicate of average particle size 2 μm and of the blue phosphor of mixed barium oxide, aluminum and magnesium doped with europium and of average particle size 2 μm On this rear slab, remove the bead of sealing material using a syringe dispenser. For this, a solution is prepared with 100 grams of PVA grade 14/135 to 200 centipoise, and 250 grams of a non-crystallizable glass frit powder of commercial reference LS0118 with an average particle size of 80 films. This cord is then

dried at 100OC for 10 minutes. The completion of the rear slab is completed by baking the entire structure produced at a temperature of 480OC for 20 minutes. The slab is then ready to be assembled with a front slab to form a plasma screen.

A second embodiment of a rear slab is described below. The soda-lime glass substrate is 1300 mm long and 750 mm wide. The rear panel must have 3360 column electrodes with a pitch of 0.4 mm.

The electrodes are produced by screen printing with a silver paste. This silver paste is prepared by mixing 100 grams of an aqueous solution of polyvinyl alcohol of grade 30/70 with 1200 centipoise, 300 grams of silver powder of average particle size 1! lm, 50 grams of a glass of lead borosilicate with 20% silica and with an average particle size of 1.5 μm and 4 grams of a commercial WLN reference defoamer. The solution is homogenized by agitation with ultrasound.

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The deposition of this paste is carried out by screen printing through a stainless steel fabric of 140 mesh per centimeter. The fabric is blocked by a resin with the exception of strips of width 180 μm corresponding to the electrodes and the edge connectors of the slab. The dough deposited is then dried in a hot air oven at 120oC for 10 minutes. The paste intended for the production of the dielectric layer is then prepared. For this, 120 grams of an aqueous solution of polyvinyl alcohol of grade 30/70 to 1200 centipoise are mixed, 150 grams of barium titanate powder with an average particle size of 1 μm, 30 grams of an aqueous solution of colloidal silica with 30% silica, 30 grams of a 22% solution of lithium silicate and 5 grams of a WLN reference commercial defoamer.

The solution is homogenized by passage through a sorter. The deposition of this paste is carried out by screen printing through a stainless steel fabric of 77 mesh per centimeter over the entire surface of the slab with the exception of a strip of 6 millimeters over the two widths of the substrate and a strip of width 20 millimeters over the two lengths of the substrate, the lengths corresponding to the position of the connectors. The dough deposited is then dried in a hot air oven at 200oC for 15 minutes. The thickness of the dry layer is 10 u. m. The first layer is then made to form the body of the barriers.

chaud à 60 C pendant 10 minutes. On procède à quatre dépôts successifs avec un séchage intermédiaire pour obtenir une épaisseur totale de 115 am pour la couche sèche. On réalise alors la couche de masquage pour le sablage qui aura également comme fonction de rendre sombre le sommet des barrières. On prépare pour cela une solution avec 100 grammes de PVA de grade 30/70 à 2000 centipoises, solution additionnée de 6 grammes d'une solution à 100 grammes par litre de bichromate d'ammonium, 40 grammes d'oxyde mixte de chrome, cobalt et aluminium de granulométrie moyenne 1.8 um, 10 grammes de triéthylène glycol et de 3 grammes d'anti-mousse de référence commerciale WLN. La solution est homogénéisée par agitation avec des ultra-sons. Le dépôt de cette pâte est réalisé par sérigraphie à travers une toile polyester de 54 mailles au centimètre sur For this, 100 grams of an aqueous solution of polyvinyl alcohol of grade 25/140 to 50 centipoises are mixed, 200 grams of alumina powder of average particle size 4 μm, 30 grams of alumina powder of average particle size 0.8 μm , 10 grams of an aqueous solution of colloidal silica containing 30% of silica and 5 grams of a commercial anti-foam agent of WLN reference. The solution is homogenized by passage through a sorter. The deposition of this paste is carried out by screen printing through a polyester fabric of 43 meshes per centimeter over the entire surface of the slab of the dielectric layer deposited previously. The dough deposited is then dried in an air oven

hot at 60 C for 10 minutes. Four successive deposits are made with intermediate drying to obtain a total thickness of 115 am for the dry layer. The masking layer for sanding is then produced, which will also have the function of making the top of the barriers dark. A solution is prepared for this with 100 grams of PVA of grade 30/70 to 2000 centipoise, solution added with 6 grams of a solution at 100 grams per liter of ammonium dichromate, 40 grams of mixed chromium oxide, cobalt and aluminum with an average particle size of 1.8 μm, 10 grams of triethylene glycol and 3 grams of commercial reference defoamer WLN. The solution is homogenized by shaking with ultrasound. The deposition of this paste is carried out by screen printing through a polyester canvas of 54 mesh per centimeter on

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toute la surface de la dalle des couches des barrières déposées précédemment. On sèche ensuite la pâte déposée dans un four à air chaud à 80 C pendant 4 minutes. L'épaisseur de cette couche sèche est de 9 ! lm. On expose alors cette couche de résine à un flux de 1500 mJ/cm2 de rayons ultra-violet de longueur d'onde 365 nm à travers un masque dont les zones sombres forment des colonnes de largeur 80 um au pas de 0.4 mm et qui correspondent à l'emplacement des futures barrières. On développe cette couche à l'eau en

l'exposant 40 secondes à un jet de gouttelettes d'eau à 35OC. On sèche ensuite la surface en portant le substrat à 100oC pendant 10 minutes puis on procède au sablage avec une poudre de carbonate de sodium. On procède ensuite à un nettoyage à l'eau froide de la surface et séchage par soufflage avec de l'air sous pression. On dépose enfin les luminophores selon un réseau de bandes au pas de 1.2 mm. On prépare pour cela une solution avec 100 grammes de PVA de grade 30/70 à 400 centipoises, 160 grammes d'une poudre de luminophore rouge d'oxyde d'yttrium dopé europium de granulométrie moyenne 2.5 nm, 2 grammes d'un tensio-actif de référence commerciale OROTAN 850 et de 5 grammes d'anti-mousse de référence commerciale WLN. La solution est homogénéisée par passage dans un tribroyeur. Le dépôt de cette pâte est réalisé par sérigraphie à travers une toile polyester de 54 mailles au centimètre sur toute la surface de la dalle des couches des barrières déposées précédemment. La toile est bouchée par une résine à l'exception de zones de largeur 0.36 mm au pas de 1.2 mm et correspondant aux bandes du luminophore rouge. On sèche ensuite la pâte déposée dans un four à air chaud à 100oC pendant 5 minutes. On procède de même pour le dépôt du luminophore vert de silicate de zinc de granulométrie moyenne 2 um et du luminophore bleu d'oxyde mixte de

barium, aluminium et magnésium dopé à l'europium et de granulométrie moyenne 2 nm. Sur cette dalle arrière, on dépose le cordon de matériau de scellement à l'aide d'un dispenseur à seringue. On prépare pour cela une solution avec 100 grammes de PVA de grade 14/135 à 60 centipoises, et 250 grammes d'une poudre de fritte de verre non cristallisable de référence commerciale Lao 118 de granulométrie moyenne 80 ! lm. Ce cordon est alors séché à 100oC pendant 10 minutes. On termine la réalisation de la dalle arrière par la cuisson de l'ensemble de la structure réalisée à une température comprise de 450OC pendant 40 minutes. La dalle est alors prête pour être assemblée avec une dalle avant pour former un écran à plasma.

the entire surface of the slab of the layers of the barriers previously deposited. The dough deposited is then dried in a hot air oven at 80 C for 4 minutes. The thickness of this dry layer is 9! lm. This layer of resin is then exposed to a flow of 1500 mJ / cm2 of ultraviolet rays of wavelength 365 nm through a mask whose dark areas form columns of width 80 µm with a pitch of 0.4 mm and which correspond at the location of future barriers. We develop this layer with water in

exposing him 40 seconds to a jet of water droplets at 35OC. The surface is then dried, bringing the substrate to 100 ° C. for 10 minutes, then sanding is carried out with a powder of sodium carbonate. The surface is then cleaned with cold water and blown dry with pressurized air. Finally, the phosphors are deposited in a network of bands with a pitch of 1.2 mm. For this, a solution is prepared with 100 grams of PVA of grade 30/70 to 400 centipoise, 160 grams of a phosphor red phosphor powder of europium doped yttrium with an average particle size of 2.5 nm, 2 grams of a tensio- OROTAN 850 commercial reference active ingredient and 5 grams of WLN commercial reference defoamer. The solution is homogenized by passage through a sorter. The deposition of this paste is carried out by screen printing through a polyester fabric of 54 mesh per centimeter over the entire surface of the slab of the layers of the barriers deposited previously. The canvas is blocked by a resin with the exception of areas of width 0.36 mm in steps of 1.2 mm and corresponding to the bands of the red phosphor. The dough deposited is then dried in a hot air oven at 100oC for 5 minutes. The same is done for the deposition of the green phosphor of zinc silicate with a mean particle size of 2 μm and of the blue phosphor of mixed oxide of

barium, aluminum and magnesium doped with europium and with an average particle size of 2 nm. On this rear slab, the bead of sealing material is deposited using a syringe dispenser. For this, a solution is prepared with 100 grams of PVA grade 14/135 to 60 centipoise, and 250 grams of a non-crystallizable glass frit powder of commercial reference Lao 118 with an average particle size of 80! lm. This cord is then dried at 100oC for 10 minutes. The completion of the rear slab is completed by baking the entire structure produced at a temperature of 450 ° C. for 40 minutes. The slab is then ready to be assembled with a front slab to form a plasma screen.

Claims (15)

 Claims: 1) A rear slab structure for a plasma display screen characterized in that the substrate carries a network of electrically conductive electrodes, a dielectric layer, a network of barriers and a network of red, green and blue phosphors deposited between the barriers, the structure also being characterized in that the dielectric layer consists of a porous material composed of a powder with an average particle size of between 0.4 and 10 μm or an airgel or a mixture of a powder of average particle size between 0.4 and 10! lm and an airgel, the composition of this porous material being an oxide or mixture of oxides or solution of oxides among the oxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkaline oxides, borosilicate or borophosphosilicate glasses, the thickness of this layer being between 3 and 30 μm. 2) A rear panel structure for a plasma display screen according to claim 1 characterized in that the composition of the porous material contains a mass fraction of less than 40% of one or more glasses with a low melting point of silicate or borosilicate of lead or bismuth 3) A rear slab structure for plasma display screen according to one of claims 1 or 2 characterized in that the barriers are made of a porous material composed of a powder of average particle size between

 0, 7 and 12 u. m or an airgel or a mixture of a powder with an average particle size of between 0.7 and 12! lm and an airgel, the composition of this porous material being an oxide or mixture of oxides or solution of oxides among the oxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkali oxides, glasses of borosilicate or borophosphosilicate, glasses with low melting point of silicate or borosilicate of lead or bismuth in mass fraction lower than 40%, the height of these barriers being between 70 and 200! lm. 4) A back tile structure for a plasma display screen according to claim 3 characterized in that the barriers have at their top a dark layer composed of a porous material consisting of a powder with an average particle size between 0.7 and 6 µm or an airgel or a mixture of a powder with an average particle size of between 0.7 and 6 μm and an airgel, the composition of this porous material being an oxide or <Desc / Clms Page number 16>  mixture of oxides or solution of oxides among the oxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkali oxides, borosilicate glasses or of borophosphosilicate, composition containing a solution of oxides chosen from oxides of iron, cobalt, copper, chromium, aluminum and nickel, composition also containing one or more glasses with a low melting point lead or bismuth silicate or borosilicate in a mass fraction of less than 70%, the thickness of this layer being between 2 and 20 μm. 5) A rear slab structure for a plasma display screen according to claim 3 characterized in that a sealing bead composed of a non-crystallizable type sealing glass is deposited at the periphery of the useful area of the slab, only the connectors at the ends of the electrodes being located outside of this sealing bead. 6) A method for producing a rear panel of a plasma display screen composed of a network of electrically conductive electrodes, a dielectric layer, a network of barriers and a network of red phosphors , green and blue deposited between the barriers and characterized in that after completion of the electrodes and their possible cooking, this process comprises only one cooking at more than 400oC and that this cooking is carried out at the end of the process for producing the rear panel, in particular after the phosphors have been deposited 7) A process for producing a rear panel of a plasma display screen according to claim 6 characterized in that the dielectric layer is produced by depositing on the electrodes a paste obtained from an aqueous solution a polyvinyl alcohol with a mass concentration between 3 and 20%, an aqueous solution optionally supplemented with anti-foaming agents or a texturing agent, and an oxide or hydroxide or a mixture of oxides or hydroxides or solution of oxides or hydroxides among the oxides or hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkali oxides, borosilicate or borophosphosilicate, with a granolumetry of between 0.4 and 10 μm, this paste optionally containing a binding agent in the form of a colloidal solution of an oxide or a hydroxide chosen from oxides and hydroxides of silicon, alumin ium, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, oxides <Desc / Clms Page number 17>  less than 3 Am of a glass of oxides whose softening temperature is less than 450oC, then drying between 50 and 200oC of this layer of paste deposited on the electrodes., the thickness of this dry layer being between 3 and 30 u. m.

 alkalis or a binding agent in the form of an oxide or hydroxide airgel chosen from oxides and hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead , bismuth, alkaline oxides or a binding agent in the form of a powder with particle size 8) A method for producing a rear panel of a plasma display screen according to claim 7 characterized in that the barriers are produced by depositing a layer which will form the body of the barriers, then by depositing a photosensitive layer intended to form a masking of the underlying layers, then by photolithography of this masking layer according to the pattern of the barriers, then by abrasion by sandblasting of the body and top layers of the barriers in places not protected by the mask. 9) A method for producing a rear panel of a plasma display screen according to claim 8 characterized in that the layer intended to form the body of the barriers is produced by depositing a paste obtained from a aqueous solution of a polyvinyl alcohol with a mass concentration between 0.5 and 8%, aqueous solution possibly added with anti-foaming agents or texturing agent, and containing an oxide or hydroxide or a mixture of oxides or hydroxides or solution of oxides or hydroxides among the oxides or hydroxides of silicon, aluminum , boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkaline oxides, borosilicate or borophosphosilicate glasses, with a particle size between 0.7 and 12 μm, this paste optionally containing a binding agent in the form of a colloidal solution of an oxide or a hydroxide chosen from oxides and hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium , cerium, tin, vanadium, lead, bismuth, alkaline oxides or a binding agent in the form of an aerogel of oxide or hydroxide chosen from oxides and hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkaline oxides or a binding agent in the form of a powder with a particle size less than 3 μm from a glass of oxides whose temperature <Desc / Clms Page number 18>  softening is less than 450oC, then drying between 50 and 200OC of this layer of paste deposited on the dielectric layer, the thickness of this dry layer being between 70 and 200 u. m. 10) A method of producing a rear panel of a plasma display screen according to claim 8 characterized in that the layer intended to form the sandblasting mask is produced by deposition and drying between 40 C and 200oC and photolithography d '' a layer of resin obtained by depositing an aqueous solution of a polyvinyl alcohol with a mass concentration of 6 to 25% in water and added with a photosensitizer chosen from sodium or potassium or ammonium dichromates or diazotized compounds, the thickness of this dry layer being between 2 and 25 μm.

11) A method for producing a rear panel of a plasma display screen according to claim 8 characterized in that the layer intended to form the sandblasting mask is produced by deposition and drying between 40 ° C. and 200 ° C. and photolithography of '' a layer of resin obtained by depositing an aqueous solution of a polyvinyl alcohol with a mass concentration of 6 to 25% in water and added with a photosensitizer chosen from sodium or potassium or ammonium dichromates or diazotized compounds, this solution also being added with a mineral filler composed of a powder with a particle size of less than 3 μm or a colloidal solution or an airgel, the composition of this mineral filler being an oxide or a hydroxide or mixture of oxides or hydroxides or solution of oxides or hydroxides among the oxides and hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkaline oxides, this charge can also be composed of glasses of borosilicate or borophosphosilicate or, in fraction less than 40% of the mass of the charge, glasses of oxides whose temperature softening is less than 450oC, the mass fraction of the mineral filler in the dough being between 0 and 20%, the thickness of this dry layer being between 2 and 25 u. m. 12) A method for producing a rear panel of a plasma display screen according to claim 9 and one of two claims 10 and 11 characterized in that a layer intended to form the top of the barriers is produced after depositing the layer intended to form the body of the barriers and before depositing the masking layer, and that this layer is obtained by depositing a paste <Desc / Clms Page number 19>  prepared from an aqueous solution of a polyvinyl alcohol with a mass concentration between 0.5 and 8%, an aqueous solution optionally added with anti-foaming agents or texturing agent, and containing a porous material consisting of a powder with an average particle size between 0.7 and 6 µm or an airgel or a mixture of a powder with an average particle size between 0.7 and 6 µm and an airgel, the composition of this porous material being an oxide or hydroxide or mixture of oxides or hydroxides or solution of oxides or hydroxides among the oxides or hydroxides of silicon, aluminum, boron, phosphorus, calcium, magnesium, barium, titanium, zirconium, cerium, tin, vanadium, lead, bismuth, alkali oxides , glasses of borosilicate or borophosphosilicate, composition added with a powder of average particle size between 0.7 and 6 u. m of a mixture of oxides chosen from oxides of iron, cobalt, copper, chromium, aluminum and nickel, this composition can also be added with one or more glasses with a low melting point of lead or bismuth silicate or borosilicate in fraction less than 70% of the mass of the filler, then drying between 50 and 200oC of this layer of paste, the thickness of this dry layer being between 2 and 20 μm. 13) A method for producing a rear panel of a plasma display screen according to claim 9 and one of two claims 10 and 11 characterized in that the paste intended to form the layer of sandblasting mask is added a powder with an average particle size of between 0.7 and 3 μm of a mixture of oxides chosen from oxides of iron, cobalt, copper, chromium, aluminum and nickel. 14) A plasma display screen characterized in that the structure of the rear panel of this screen is produced according to claim 1 or 2 15) Plasma display screen according to claim 14 characterized in that the structure of the rear panel of this screen is produced according to claim 3