KR20010029403A - Composite of dielectric for display - Google Patents

Abstract

PURPOSE: A dielectric substance composition for a display is provided which has a low firing temperature, high transmissivity and high permittivity . CONSTITUTION: The dielectric substance composition comprises: (i) 50-85 wt.% of PbO; (ii) 7-25 wt.% of SiO2; (iii) 7-25 wt.% of B2O3; (iv) 0-15 wt.% of ZnO; (v) 0-5 wt.% of SrO; (vi) 0-5 wt.% of Bi2O3; (vii) 0-5 wt.% of CeO2; (viii) 0-5 wt.% of MgO; and (ix) 0-5 wt.% of CaO, where (SiO2+B2O3)≤15-30 wt.% and (ZnO+SrO+Bi2O3+CeO2+MgO+Cao)≤10 wt.%.

Description

Dielectric composition for display device {COMPOSITE OF DIELECTRIC FOR DISPLAY}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to dielectric compositions for display devices, and to dielectric compositions having low firing temperatures, high transmittances, and high dielectric constants.

Recently, various display devices such as a liquid crystal display (LCD), a plasma display (PDP), and a field effect display (FED) have been developed. Among them, the plasma display is an apparatus for providing an image by using light emitted from the plasma during gas discharge, and the discharged plasma is separated by a fine partition wall to form a unit cell.

As shown in FIG. 1, the cross-sectional structure of the plasma display includes an upper plate 11 and a lower plate 1, and an address electrode 3, a transparent electrode 12, a bus electrode 13, and a partition wall 5 therebetween. And the protective film 15, the phosphor 6, and the like. In the plasma display, an image is generated by selectively emitting a unit cell formed by a fine partition wall 5 by a driving circuit. When a plasma display is realized, vacuum plasma of plasma generated from a unit cell of several hundred micrometers is used. As the visible light emitted from the phosphor 6 passes through the top plate 11, the image is transmitted to the outside. In the case of the surface-discharge AC-plasma display as shown in FIG. 1, since the wall charge is used, the higher the dielectric constant of the top dielectric 14 is, the lower the discharge voltage is, which is advantageous for improving luminous efficiency.

In addition, in the case of visible light emitted from the phosphor 6 excited by vacuum ultraviolet rays, the upper dielectric material 14 has a high transmittance, and the lower the dielectric material 4 and the partition wall 5 have a higher reflectivity, the better the plasma display luminous efficiency. Do.

Processors used to form plasma display dielectric materials include screen printers, which have low thermal expansion coefficient, thermal stability, low firing temperature and dense structure, electrode materials and MgO protective films. Properties such as good matching, high light transmittance of the top dielectric, and high light reflectance of the bottom dielectric and partition material.

The composition of the parent glass of most dielectric materials currently applied for this property is shown in Table 1. Conventionally, PbO-B ₂ O ₃ -SiO ₂ -based glass containing 40 to 80% of a large amount of PbO component is made into a fine powder of 10 μm or less, mixed with an organic solvent, and then screen printed. It is made of a paste or tape casting slurry and applied to a glass substrate to a thickness of about 10 to 25 μm. After application, it is plasticized at 300 to 350 ° C. for 15 to 20 minutes to remove the organic solvent, and then 580 to Sintering is carried out at a temperature range of 590 DEG C to obtain a transparent dielectric layer.

Furtherance Frosted glass PbO: 50 ~ 85 wt%, SiO ₂ : 10 ~ 20wt%, B ₂ O ₃ : 10 ~ 20wt%, K ₂ O: 0 ~ 10wt%, Na ₂ O: 0 ~ 10wt%

However, in the case of the current top dielectric, as shown in Table 2, the plasma discharge voltage is increased due to the low dielectric constant (12-14), the light emission efficiency is decreased due to the low light transmittance (75-85%), and the high firing temperature is achieved. Due to this, there is a problem that the glass substrate is deformed or broken.

Firing temperature Light transmittance (400 ~ 800nm) Dielectric constant (1 MHz) Coefficient of thermal expansion Withstand voltage 580 ~ 590 ℃ 75 to 85 12 to 14 65 ~ 90 × 10 ^-7 / ℃ 1.5KV

In addition, in the case of the partition material, pores remain inside the partition after firing, so that pollutant atoms are adsorbed, thereby reducing discharge purity and discharge efficiency. In addition, the partition wall is easily collapsed by an external impact, and has a disadvantage in that luminous efficiency is low due to low reflectance.

SUMMARY OF THE INVENTION An object of the present invention is to increase the dielectric constant of a dielectric having a low dielectric constant, to increase luminous efficiency, and to reduce dielectric manufacturing process time by baking at a low temperature, and to provide a dielectric composition for a display device capable of satisfying thermal and electrical characteristics. have.

In addition, another object of the present invention is to provide a dielectric composition for a display device which increases the density and reflectance of the partition wall, maintains the partition shape against external impact, and improves luminous efficiency.

1 is a schematic diagram schematically showing the structure of a plasma display.

Figure 2a is a SEM photograph showing the surface roughness of the conventional lower plate dielectric.

Figure 2b is a SEM photograph showing the surface roughness of the lower plate dielectric according to the present invention.

Figure 3a is a graph showing the surface roughness of the conventional lower plate dielectric.

Figure 3b is a graph showing the surface roughness of the lower plate dielectric according to the present invention.

4A is a graph showing the reflectivity of a conventional lower plate dielectric.

Figure 4b is a graph showing the reflectivity of the lower plate dielectric according to the present invention.

*** Explanation of symbols for the main parts of the drawing ***

1: 2 Bottom 2: Lower Film

3: address electrode 4: lower plate dielectric

5: bulkhead 6: phosphor

11: top plate 12: transparent electrode

13: Bus electrode 14: Top dielectric

It is a shield 15

This invention is a dielectric composition for display elements, and has the composition of the following base glass.

PbO: 50 to 85 wt%, SiO ₂ : 7 to 25 wt%, B ₂ O ₃ : 7 to 25 wt%, ZnO: 0 to 15 wt%, SrO: 0 to 5 wt%, Bi ₂ O ₃ : 0 to 5 wt%, CeO ₂ : 0 ~ 5wt%, MgO: 0 ~ 5wt%, CaO: 0 ~ 5wt%

Here, (SiO ₂ + B ₂ O ₃ ) ≤ 15-30 wt%,

(ZnO + SrO + Bi ₂ O ₃ + CeO ₂ + MgO + CaO) ≤ 10 wt%.

In addition, the present invention is selected from PbTiO ₃ , Bi ₂ O ₃ , BaTiO ₃ , CaTiO ₃ , CaSnO ₃ , BaZrO ₃ , CaZrO ₃ , PbZrO ₃ , CaSiTiO as the oxide filler, if necessary for the dielectric composition of the above-mentioned composition range It further comprises any one or more, and the ratio of the mother glass and the oxide filler is characterized in that 100: 0 ~ 50.

On the other hand, in the dielectric production method, the dielectric composition is paste or slurry, and then formed by directly printing a thick film on the substrate by screen printing, tape casting, or the like, and then firing it with green tape. In this case, the firing temperature of the dielectric composition is characterized by having a low firing temperature of 560 ℃ or less.

In addition, the present invention is characterized in that the firing temperature of the composition further comprises an oxide filler in the dielectric composition is 550 ~ 600 ℃.

Table 3 shows the features of the present invention.

Furtherance Frosted glass PbO: 50 to 85 wt%, SiO ₂ : 7 to 25 wt%, B ₂ O ₃ : 7 to 25 wt%, ZnO: 0 to 15 wt%, SrO: 0 to 5 wt%, Bi ₂ O ₃ : 0 to 5 wt%, CeO ₂ : 0 ~ 5wt%, MgO: 0 ~ 5wt%, CaO: 0 ~ 5wt% (SiO ₂ + B ₂ O ₃ ) ≤ 15 ~ 30wt% (ZnO + SrO + Bi ₂ O ₃ + CeO ₂ + MgO + CaO) ≤ 10 wt% Filler PbTiO ₃ , Bi ₂ O ₃ , BaTiO ₃ , CaTiO ₃ , CaSnO ₃ , BaZrO ₃ , CaZrO ₃ , PbZrO ₃ , CaSiTiO Parent glass, filler ratio Bust Glass: Filler 100: 0 ~ 50

The dielectric composition according to the present invention can be used as a top or bottom dielectric material for plasma displays. It may also be used as a barrier material or black matrix by further adding other ingredients as described below. In addition, the present invention can be used for dielectric materials of various display devices.

Unlike K ₂ O and Na ₂ O in conventional dielectric compositions for displays, the present invention improves the dielectric constant by including ZnO, SrO, Bi ₂ O ₃ , CeO ₂ , MgO, CaO and the like instead of these materials. At the same time, the firing temperature was lowered and other physical properties were improved. In particular, the dielectric constant can be further improved by adding an oxide filler in a predetermined ratio depending on the purpose of use.

The characteristics of the dielectric composition of the present invention will be described in detail through a method of manufacturing a dielectric for plasma display.

The raw material powder is weighed according to the designed composition ratio, mixed in a mixer for a predetermined time, and then melted in a platinum crucible using an electric melting furnace. At this time, the melting conditions were melted for about 1 to 5 hours at about 1200 ~ 1500 ℃, and then stirred several times using a stirrer to maintain homogeneity, and then passed the molten glass through a quenching roller (quenching roller) The quenched, quenched glass shards were milled for 16 hours by ball milling, and then passed through # 170 and # 270 siever in order to obtain glass powder having a particle size of 10 μm or less in average particle size. At this time, the milling condition is 250g of mill jar filling, 44EA / jar of cylinder type ball, milling speed 70rpm, lubricant is IPA solution (2ml), milling time is 16 hours.

The glass powder thus prepared is placed in a dry oven at 150 ° C. and dried for 2 hours or more, and then mixed with a vehicle solution in which a predetermined amount of an organic binder and an organic solvent are mixed, for screen printing paste, and Make a slurry for tape casting.

At this time, the mixing ratio of the glass powder and the vehicle solution is usually 95: 5 to 50: 50 by weight, preferably about 70: 30, and the ratio is adjusted according to the paste or slurry state.

In addition, the vehicle may include 40 to 90 wt% of diethylene glycol mono-n-butyl ethyl acetate (BCA), 3 to 20 wt% of ethyl cellulose (Ethylcellulose) and diethylene glycol mono-ene- Butyl ether (Diethylene Glycol Mono-n-Buthyl Ether) is composed of 3 ~ 40wt%.

On the other hand, when a suitable amount of photosensitive resin is mixed in a vehicle solution, it can be applied also as a photosensitive partition material.

Although the glass powder prepared from the dielectric composition of the present invention varies depending on the thick film process, a viscosity of about 70,000 to 100,000 cps is appropriate for screen printing paste, and a viscosity of about 700 to 1,000 cps is suitable for a slurry for tape casting. It is suitable.

In addition, the firing temperature was determined from the DTA (Differential Thermal Analysis) analysis of the mixed powder, in the case of the dielectric composition according to the present invention, after applying a green tape having a thickness of about 200㎛ on the glass substrate by paste or tape casting After removing the organic solvent and the organic binder by plasticizing at a temperature of 350 to 550 ° C., firing at a temperature of 550 to 600 ° C. may form an upper or lower plate dielectric.

Looking at the physical properties of the dielectric composition according to the present invention are shown in Table 4. Compared with the conventional dielectric composition, the firing temperature is lowered, and the light transmittance, the dielectric constant, and the like are remarkably improved.

Firing temperature Light transmittance (400 ~ 800nm) Dielectric constant (1 MHz) Coefficient of thermal expansion Withstand voltage 550 ~ 600 ℃ 80-95 13 to 35 60 ~ 85 × 10 ^-7 / ℃ 1.5KV

A lower plate dielectric was prepared from the dielectric composition of the present invention and its properties were investigated. 2A and 2B are SEM photographs showing surface roughnesses of a conventional lower plate dielectric and a lower plate dielectric prepared from the dielectric composition of the present invention, respectively. While the conventional lower plate dielectric has a rough surface, the lower plate dielectric according to the present invention can be seen that the surface is flattened and smooth. 3A and 3B are graphs showing surface roughnesses of the conventional lower plate dielectric and the lower plate dielectric according to the present invention, respectively. The conventional lower plate dielectric has a surface roughness (Ra) of 3886 Å, whereas the lower plate dielectric of the present invention has a surface roughness of 1486 Å and shows very improved results. These values are shown as the average value of roughness for the scan distance after scanning a portion of the lower dielectric. Here, roughness means surface flatness of each scan point, and the scan distance was based on 100 μm. In addition, while the difference between the highest height (12,000) and the minimum height (-6000) is large in FIG. 3A, it can be seen that the difference is not sharp from 8,000 to 1000 in FIG. 3B.

4A and 4B are graphs showing reflectances of the conventional lower dielectric and the lower dielectric according to the present invention, respectively. Laser light in the visible region was incident on the dielectric layer, and its reflection was measured and shown according to each wavelength. In the case of the conventional lower plate dielectric, reflectances of 50%, 43%, and 37% are respectively shown at 450 nm, 550 nm, and 700 nm, whereas the lower plate dielectric according to the present invention shows very improved reflectances of 65%, 58%, and 49%, respectively. have.

As described above, the present invention, unlike the prior art, ensures the characteristics of thermal stability and high dielectric constant as a dielectric material for display elements, solves the problem of deformation of the substrate by using glass powder of low firing temperature, and fires as the firing temperature is lowered. Less time can be used to shorten the overall process.

In addition, since the transition point is low and the surface is smoothly formed, it is possible to obtain an effect of increasing the adhesive force with the partition wall when used as the top dielectric. At the same time, it is possible to obtain stable voltage characteristics by minimizing the generation of pores.

On the other hand, the dielectric composition according to the present invention can be used as a white composition for the partition material by mixing additives such as Al ₂ O ₃ , TiO ₂ , ZnO, ZrO ₂ , BPO ₄ , PbTiO ₃ , BaTiO ₃ . In addition, a carbon-based compound such as Co (OH) ₂ , CuOCr ₂ O ₃ , Cr-Fe-Co compound, graphite, or the like may be mixed with the dielectric composition to be used as a black composition for a black matrix or a barrier material. .

As such, when the dielectric composition of the present invention is used as a partition material, a compact structure is possible, and thus, the shape of the partition is maintained against external impact, and since there are few pores, the adsorption of polluting atoms is not only reduced, but the luminous efficiency is increased by increasing the reflectance. Can be increased.

Meanwhile, the dielectric material composition of the present invention can be applied to various display dielectrics and spacer materials such as inorganic EL and field effect displays in addition to plasma displays.

According to the present invention, the dielectric constant of the dielectric is improved compared to the conventional dielectric composition for plasma display, the luminous efficiency is increased, and the adhesion to the partition wall can be increased by good surface planarization, and at the same time, the generation of pores can be minimized to obtain stable voltage characteristics. In addition, low-temperature firing can prevent deformation of the substrate, reduce process time, and produce a dielectric that satisfies other thermal and electrical properties. In addition, when applied as a partition material, it has a compact structure, which is resistant to external impact, reduces the adsorption of polluting atoms, and increases luminous efficiency by increasing reflectance.

Claims (10)

The composition as follows PbO: 50 to 85 wt%, SiO ₂ : 7 to 25 wt%, B ₂ O ₃ : 7 to 25 wt%, ZnO: 0 to 15 wt%, SrO: 0 to 5 wt%, Bi ₂ O ₃ : 0 to 5 wt%, CeO ₂ : 0 ~ 5wt%, MgO: 0 ~ 5wt%, CaO: 0 ~ 5wt%, Here, (SiO ₂ + B ₂ O ₃ ) ≤ 15 ~ 30wt%, A dielectric composition for a display device satisfying a relationship of (ZnO + SrO + Bi ₂ O ₃ + CeO ₂ + MgO + CaO) ≤ 10 wt%. The method of claim 1, wherein the dielectric composition further comprises at least one selected from the group consisting of PbTiO ₃ , Bi ₂ O ₃ , BaTiO ₃ , CaTiO ₃ , CaSnO ₃ , BaZrO ₃ , CaZrO ₃ , PbZrO ₃ , CaSiTiO as an oxide filler Dielectric composition for display device. The dielectric composition of claim 2, wherein the ratio of the dielectric composition and the oxide filler further included is 100: 0 to 50. A dielectric composition for display elements, wherein the dielectric composition of claim 1 is used as a top or bottom dielectric material of a plasma display. The dielectric composition of claim 1, further comprising at least one selected from Al ₂ O ₃ , TiO ₂ , ZnO, ZrO ₂ , BPO ₄ , PbTiO ₃ , and BaTiO ₃ as an additive to the dielectric composition. A dielectric composition for display elements, wherein the dielectric composition of claim 5 is used as a barrier material of a plasma display. The dielectric composition of claim 5, further comprising any one or more selected from Co (OH) ₂ , CuOCr ₂ O ₃ , Cr-Fe-Co compounds, and carbon-based compounds. A dielectric composition for display elements, wherein the dielectric composition of claim 7 is used as a black matrix or barrier material of a plasma display. The dielectric composition of claim 1, wherein a vehicle solution is mixed with the dielectric composition in a range of 5 to 50 wt%. Diethylene Glycol Mono-n-Buthyl Ethyl Acetate (BCA) 40-90 wt%, Ethylcellulose 3-20 wt% and Diethylene Glycol Mono-N-butylethyl acetate Glycol Mono-n-Buthyl Ether) Dielectric composition for a display device comprising a vehicle solution consisting of 3 to 40wt%.