KR20090080325A - Pb free paste of sealant for plasma display panel and plasma display panel comprising Pb free sealant prepared by baking the paste - Google Patents

Abstract

Pb-free sealing paste for plasma display panels and the plasma display panel comprising the sintered sealing paste are provided to show excellent dispersibility as well as a shape retention property even at high temperature. The area of hysteresis curve of Pb-free sealing paste for plasma display panels is 4500 - 20000 Pa/s. The Pb-free sealing paste for plasma display panels is composed of three or more compounds selected from the group consisting of MgO, Al2O3, SiO2, Bi2O3, BaO and ZnO. The Pb-free sealing paste contains three or more compounds selected from the group consisting of 5-12wt% of ZnO, 7.5-30wt% of B2O3, 57-85wt% of Bi2O3 and 0-1wt% of SiO2. The plasma display panel is coated with the Pb-free sealing paste and they are sintered. The sintering process is performed at 460-500°C.

Description

Plasma display panel comprising Pb free paste of sealant for plasma display panel and plasma display panel comprising Pb free sealant prepared by baking the paste}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a plasma display panel including a lead-free paste for a plasma display sealant and a lead-free sealant fired therefrom. The present invention relates to a plasma display panel including a lead-free sealing material fired by firing.

Plasma display panel is characterized by easy to enlarge the screen, self-luminous type, good display quality, fast response speed. It is attracting attention as a wall-mounted display together with LCDs because it can be thinned.

In general, a plasma display panel applies a predetermined voltage to an electrode while a gas is charged between two electrodes installed in an enclosed space so that a glow discharge occurs and the ultraviolet rays generated during the glow discharge are generated. As a result, the phosphor layer formed in a predetermined pattern is excited to form an image.

The plasma display panel is classified into a direct current type, an alternating current type, and a mixed type according to a driving method. And, depending on the electrode structure, it is divided into having at least two electrodes required for discharge and having three electrodes. In the case of the direct current type, an auxiliary anode is added to induce the auxiliary discharge. In the case of the alternating current type, an address electrode is introduced to separate the selective discharge and the sustain discharge to improve the address speed.

In addition, the AC type may be classified into a counter electrode and a surface discharge electrode structure according to the arrangement of the electrodes for discharging. In the case of the counter electrode structure, the two sustain electrodes forming the discharge are respectively the front substrate and the back substrate. The surface discharge type electrode structure is a structure in which the discharge is formed on one plane of the substrate because two sustain electrodes forming the discharge are positioned on the same substrate.

As a sealing material used in the plasma display panel, a paste containing PbO was used for the purpose of lowering the melting temperature in the process, but regulations such as Restriction of the use of Certain Hazardous Ssubstance (RoHS) Due to this, environmentally friendly plasma display panels have become a big issue, and lead-free materials are being developed to replace PbO-based sealants.

The first technical problem to be achieved by the present invention is to provide a lead-free paste for plasma display sealing material excellent in dispersibility and excellent shape retention at high temperature.

It is a second object of the present invention to provide a plasma display panel including a lead-free sealing material having excellent shape retention at high temperatures.

The present invention for the first technical problem,

Plasma display with a hysteresis curve area of 4500 to 20000 Pa / s, measured at 19.8 ° C with increasing shear force from 1 / s to 60 / s for 60 seconds and decreasing shear force from 60 / s to 1 / s for 60 seconds Provides lead-free paste for use.

According to one embodiment of the invention, the lead-free paste preferably comprises at least three selected from the group consisting of MgO, Al ₂ O ₃ , SiO ₂ , Bi ₂ O ₃ , BaO and ZnO.

According to one embodiment of the invention, the lead-free paste is ZnO 5 to 12% by weight, B ₂ O ₃ 7.5 to 30% by weight, Bi ₂ O ₃ 57 to 85% by weight and SiO ₂ 0 to 1% by weight It is preferable to include at least three selected from.

The present invention for the second technical problem,

Provided is a plasma display panel including a lead-free sealing material coated with a lead-free paste for plasma display sealing material and fired.

According to one embodiment of the invention, the firing process is preferably carried out at 460 to 500 ℃.

According to one embodiment of the invention, the XRD analysis of the lead-free sealing material shows a (002) peak or (004) peak in the vicinity of 2θ = 18 or 2θ = 37.

According to one embodiment of the present invention, the lead-free sealant may include crystals of a hexagonal structure.

According to one embodiment of the present invention, the lead-free sealant may include bismuth oxide crystals.

Hereinafter, the present invention will be described in detail.

The present invention relates to a lead-free paste for plasma display, wherein the curved area of hysteresis measured with increasing shear force from 1 / s to 60 / s for 60 seconds at 19.8 ° C. and decreasing shear force from 60 / s to 1 / s for 60 seconds is obtained. It provides a lead-free paste for plasma display of 4500 to 20000 Pa / s.

When the hysteresis curve area is within the above range, the lead-free paste is excellent in dispersibility, slow in viscosity change over time, and uniform in line width upon application.

According to one embodiment of the invention, the lead-free paste preferably comprises at least three selected from the group consisting of MgO, Al ₂ O ₃ , SiO ₂ , Bi ₂ O ₃ , BaO and ZnO.

According to another embodiment of the present invention, the lead-free paste is composed of 5 to 12% by weight of ZnO, 7.5 to 30% by weight of B ₂ O ₃ , 57 to 85% by weight of Bi ₂ O ₃ and 0 to 1% by weight of SiO ₂ It may include three or more selected from the group. The lead-free paste within the composition range has a hysteresis area in the range.

In addition, the lead-free paste may include a solvent or a resin as an organic vehicle. The solvent may be a solvent generally used in organic vehicles, and the resin may be acrylic or nitrocellulose.

The lead-free paste according to the present invention may be applied to a plasma display panel and fired to manufacture a plasma display panel including a lead-free sealing material having excellent shape retention performance.

Referring to FIG. 1, the plasma display panel includes a front panel 210 and a rear panel 220.

The front panel 210 is disposed on the front substrate 211 and the rear of the front substrate (more specifically, the rear surface of the front substrate) and the sustain electrode pairs 214 extending over the light emitting cells 226 in a row. And a front dielectric layer 215 and a passivation layer 216 covering the sustain electrode pairs.

The rear panel 220 is disposed on the rear substrate 221 disposed in parallel with the front substrate, and in front of the rear substrate (more specifically, the front substrate 221a of the rear substrate) and the sustain electrode pairs. Barrier ribs formed between the address electrodes 222 extending to intersect, the rear dielectric layer 223 covering the address electrodes, and the front substrate and the rear substrate (more specifically on the rear dielectric layer) to partition the light emitting cells 226. 224, and a red fluorescent film 225a, a green fluorescent film 225b, and a blue fluorescent film made of red, green, and blue phosphors that emit visible light in response to ultraviolet rays emitted from the discharge gas by the sustain discharge. 225c.

The blue fluorescent film, the red fluorescent film and the green fluorescent film can all be used as long as they are commonly available in the manufacture of plasma display panels.

The front substrate 211 and the rear substrate 221 is generally formed of glass, the front substrate is preferably a high light transmittance.

The address electrodes 222 disposed on the front surface 221a of the rear substrate and extending over the light emitting cells 226 are typically formed of a metal having high electrical conductivity, for example, Al. The address electrode 222 is used for the address discharge together with the Y electrode 312. The address discharge is a discharge for selecting the light emitting cells 226 to emit light, and the sustain discharge described later may occur in the light emitting cells 226 in which the address discharges are made.

The address electrodes 222 are covered by the rear dielectric layer 223. The rear dielectric layer 223 prevents charged particles from colliding with the address electrodes 222 and damaging the address electrodes during address discharge. The rear dielectric layer 223 is formed as a dielectric capable of inducing charged particles. Such dielectrics include PbO, B ₂ O ₃ , SiO _2, and the like.

A partition wall 224 partitioning the light emitting cells 226 is formed between the front substrate 211 and the rear substrate 221. The partition wall 224 is discharged between the front substrate 311 and the rear substrate 221. The space is secured, crosstalk between adjacent light emitting cells 226 is prevented, and the surface area of the phosphor layer 225 is increased. The partition wall 224 is formed of a glass component including elements such as Pb, B, Si, Al, and O, and a filler such as ZrO ₂ , TiO ₂ , and Al ₂ O ₃ as necessary. And pigments such as Cr, Cu, Co, Fe, TiO ₂ .

The sustain electrode pairs 214 extend in a direction crossing the direction in which the address electrode 222 extends over the light emitting cells 226 in a row. The sustain electrode pair 214 includes a pair of sustain electrodes 212 and 213 causing a sustain discharge, and the sustain electrode pair 214 is arranged in parallel on each other at predetermined intervals on the front substrate 211. It is. One of the sustain electrodes 212 and 213 is the X electrode 213 and the other is the Y electrode 212. The sustain discharge is caused by the potential difference between the X electrode 213 and the Y electrode 212.

Each of the X electrode 213 and the Y electrode 212 includes the transparent electrodes 213b and 212b and the bus electrodes 213a and 212a. However, in some cases, the X electrode 213 and the Y electrode 212 are common to the scan electrode only with the bus electrode without the transparent electrode. An electrode may be configured.

The transparent electrodes 213b and 212b are formed of a transparent material which is a conductor and does not prevent the light emitted from the phosphor from advancing to the front substrate 211. Such materials include indium tin oxide (ITO) and the like. However, since the transparent conductor such as ITO has a large resistance, if the sustain electrode is composed only of the transparent electrode, the voltage drop in the longitudinal direction of the transparent electrode becomes large, and thus, the power required to drive the plasma display panel increases and the image is increased. Will slow down the response. In order to improve this, bus electrodes 213a and 212a formed of a metal having high electrical conductivity, for example, Ag, are disposed at the outer end of the transparent electrode.

The sustain electrodes 212 and 213 are covered by the front dielectric layer 215. The front dielectric layer 215 can prevent the adjacent X electrode 213 and the Y electrode 212 from being directly energized during the sustain discharge, and prevent the charged particles from damaging the sustain electrodes 212 and 213 by damaging them. there is a high transmittance is formed as a dielectric, as this dielectric material include _{PbO, B 2 O 3, SiO} 2.

A passivation layer 216 may be formed between the front dielectric layer 215. At this time, the protective film prevents charged particles from colliding with the front dielectric layer 215 during the sustain discharge, and emits a lot of secondary electrons during the sustain discharge. The protective film may be formed as MgO.

The discharge gas is filled in the light emitting cell 226. The discharge gas is, for example, a Ne-Xe mixed gas containing 5% to 10% of Xe, and at least a part of Ne may be replaced with He as necessary.

A lead-free paste for a plasma display sealant according to the present invention is applied and dispensed as a sealant disposed between the front panel 210 and the rear panel 220 to bond both panels.

According to one embodiment of the invention, the firing process is carried out at 460 to 500 ℃. When firing at a temperature lower than 460 ℃ may not be enough firing, there may be a fear of "cold cell" defects due to vacuum failure or contamination at the time of sealing due to unbaking, and when firing at a temperature higher than 500 ℃ The "spreadability" due to the high temperature viscosity of the frit is increased, there may be a "noise problem" due to the height problem with the bulkhead.

The firing time is preferably 7 hours to 8 hours. In this range, the sealing material exhibits optimum physical properties.

2Al₂O₃5SiO₂) 구조의 성분이 포함된 것을 의미하며, (004) 피크는 Bi₂O_3-x 성분이면서 헥사고날 구조 (hexagonal structure)의 (004) c-축 방향 우선배향 성장 결정이 포함된 것을 의미한다. 이러한 결정의 존재로 인하여, 플라즈마 디스플레이 패널이 고온에서 장시간 동안 작동하는 경우에도 밀봉재는 유동성이 적어 형상을 유지하게 되므로, 내부 격벽과 밀봉재 부위의 높이가 균일하게 유지되어 소음 발생이 현저히 개선되는 효과가 있다. (Bi₂O_{3 -x}의 X는 결 정화된 부분의 성분을 측정했을 때 O의 비율이 Bi에 대비 3/2배에 조금 부족하다는 것을 의미한다)According to another embodiment of the present invention, when the lead-free sealant is analyzed by XRD after firing, a (002) peak or (004) peak is observed around 2θ = 18 or 2θ = 37. (002) peak is Cordierite (Cordierite: 2MgO

2Al ₂ O ₃ 5SiO ₂ ) is included, the (004) peak is Bi ₂ O _3-x component and (004) c-axis preferred orientation growth crystals of the hexagonal structure (hexagonal structure) It means to be included. Due to the presence of such a crystal, even when the plasma display panel is operated for a long time at a high temperature, the sealing material has a low fluidity and maintains a shape. Therefore, the height of the inner partition and the sealing part is kept uniform, which significantly improves noise generation. have. (X in Bi ₂ O _{3 -x} means that the proportion of O is slightly less than 3/2 times that of Bi when measuring the component of the purified part)

Hereinafter, preferred examples and comparative examples of the present invention are described. The following examples are described for the purpose of more clearly expressing the present invention, but the contents of the present invention are not limited to the following examples.

Example

Example  1: manufacture of lead-free paste 1

ZnO 10.2% by weight, 9.0% by weight of B ₂ O ₃ , 80.5% by weight of Bi ₂ O ₃ , 800 g of powder of SiO ₂ 0.3% by weight, 160 L of solvent and 40 g of acrylic resin were added and stirred for 3 hours. Paste 1 was prepared.

Hysteresis was measured for the lead-free paste 1 with increasing shear force from 1 / s to 60 / s for 60 seconds at 19.8 ° C. and decreasing shear force from 60 / s to 1 / s for 60 seconds. The results are shown in FIG. The area of each hysteresis curve was 11080 Pa / s.

Example  2: plasma  Display panel assembly

A 30 μm thick dielectric layer was formed on the electrode layer of the front substrate having the electrode layer formed thereon, and a MgO protective layer was deposited on the transparent dielectric layer by physical vapor deposition (PVD) to form a front substrate.

A phosphor slurry was prepared by mixing 6 parts by weight of ethyl cellulose as a binder with respect to 100 parts by weight of a mixed solvent of butylcarbitol acetate and terpineol in a weight ratio of 3: 7, and mixing BaMgAl ₁₀ O ₁₇ : Eu as a blue phosphor. The prepared phosphor slurry was applied inside the discharge cell of the first substrate on which the partition wall was formed, and the first substrate on which the phosphor slurry was applied was dried and baked at 120 ° C. to form a blue phosphor layer. In addition, a phosphor substrate of (Y, Gd) BO ₃ : Eu and ZnSiO ₄ : Mn was formed in the red and green discharge cells in the same manner to prepare a back substrate.

The lead-free paste 1 was applied using a dispenser to bond the prepared back substrate and the front substrate, and then fired at 500 ° C. for 8 hours, followed by exhaust, gas injection, and aging. Was prepared.

Comparative example

Comparative example  1: Manufacturing Flexible Paste 1

3 wt% SiO ₂ , 11 wt% Al ₂ O _3, 12 wt% B ₂ O ₃ , 800 g of Pb 74 wt%, 160 L of solvent, and 40 g of acrylic resin were added and stirred for 3 hours to prepare flexible paste 1 Prepared.

Hysteresis was measured for the paste of Comparative Example 1 under the same conditions as in Example 1. The area of the hysteresis curve was 4012 Pa / s.

Comparative example  2: plasma  Display panel assembly

The panel was assembled similarly to Example 3 except having used the flexible paste 1 of the comparative example 1. In this process, when the paste of Comparative Example 1 was applied using a dispenser, a problem of uneven line width was observed.

XRD  Measure

The pastes of Example 1 and Comparative Example 1 were calcined at 500 ° C. for 20 minutes and then analyzed using XRD. XRD measurement conditions are as follows.

XRD  Measuring conditions

Tube voltage & tube current: 40 kV X 40mA

Scan method, range, step, time: continuous scan, 10˚ ~ 90˚, 0.02˚, 5sec / step

Slit system: D.S. = A.S.S. = 1.0 °, R.S. = 0.2 mm

3A and 3B are graphs showing the results of XRD analysis after baking the pastes of Example 1 and Comparative Example 1 at 500 ° C. for 20 minutes. 3a and 3b, it can be seen that in Example 1, unlike in Comparative Example 1 (004) peak is observed. This is a peak due to the presence of crystals of bismuth oxide, which could be confirmed by an optical microscope.

Figures 4a, 4b and 4c is an enlarged photograph of the surface observed after firing the paste of Example 1 for 20 minutes at 500 ℃. 4A, 4B and 4C, it can be seen that bismuth oxide crystals were formed after firing.

plasma  Display panel performance comparison

The plasma display panels of Example 2 and Comparative Example 2 were operated for 2 hours, and noise generation was compared. As a result, it was confirmed that the plasma display panel of Example 2 was significantly less noise than the plasma display panel of Comparative Example 2.

The presence of bismuth oxide crystals in the sealing material was significantly higher in noise generation even after the plasma display panel of Example 2 using the lead-free paste of Example 1 than the plasma display panel of Comparative Example 2 using the flexible paste of Comparative Example 1. It is consistent with the fact that it has been improved.

1 is a perspective view schematically showing a conventional plasma display panel.

2 is a graph measuring hysteresis of the lead-free paste of Example 1. FIG.

3A and 3B are graphs showing the results of XRD analysis after firing the pastes of Example 1 'and Comparative Example 1. FIG.

4A, 4B and 4C are enlarged photographs of the surface observed after firing the paste of Example 1 at different magnifications, respectively.

Claims (8)

Plasma display with a hysteresis curve area of 4500 to 20000 Pa / s, measured at 19.8 ° C with increasing shear force from 1 / s to 60 / s for 60 seconds and decreasing shear force from 60 / s to 1 / s for 60 seconds Lead-free paste for sealants. The lead-free paste of claim 1, wherein the lead-free paste comprises at least three selected from the group consisting of MgO, Al ₂ O ₃ , SiO ₂ , Bi ₂ O ₃ , BaO, and ZnO. The method of claim 1, wherein the lead-free paste is selected from the group consisting of 5 to 12% by weight of ZnO, 7.5 to 30% by weight of B ₂ O ₃ , 57 to 85% by weight of Bi ₂ O _3, and SiO ₂ 0 to 1% by weight. A lead-free paste for plasma display sealing material comprising the above. A plasma display panel comprising a lead-free sealing material obtained by applying and baking the lead-free paste for plasma display sealing material according to any one of claims 1 to 3. The method of claim 4, wherein Wherein the firing process is performed at 460 to 500 ° C. The method of claim 4, wherein XRD analysis results of the lead-free sealing material characterized by showing a (002) peak or (004) peak in the vicinity of 2θ = 18 or 2θ = 37. The method of claim 4, wherein And the lead-free sealant comprises crystals of a hexagonal structure. The method of claim 4, wherein And the lead-free sealant comprises bismuth oxide crystals.

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