JP2007269590A - Glass composition and display panel using the same - Google Patents

Abstract

[PROBLEMS] To produce a display panel that does not contain harmful lead, has a low dielectric constant, has a low softening point, has a high glass transition point, has a good thermal expansion coefficient matching with the substrate, has high water resistance, and is highly reliable. A possible glass composition is provided.
In the oxide glass, the ratio of elements excluding oxygen (O) among the contained elements is expressed in atomic%, boron (B) is more than 72% and 88% or less, lithium (Li), The total amount of sodium (Na) and potassium (K) is 6% to 16%, the total of magnesium (Mg), calcium (Ca), strontium (Sr), and barium (Ba) is 1% to 8%, silicon A glass composition in which (Si) is 0% or more and 12% or less and zinc (Zn) is more than 2% and 18% or less.
[Selection] Figure 1

Description

  The present invention relates to a glass composition suitable for electrode coating and a display panel using the same.

  In display devices and integrated circuits such as plasma display panels (hereinafter abbreviated as PDP), field emission displays, liquid crystal display devices, fluorescent display devices, ceramic laminated devices, and hybrid integrated circuits, electrodes made of Ag, Cu, etc. are provided on the surface thereof. And a substrate having wiring is used. In order to protect these electrodes and wirings, there are cases where they are covered with an insulating glass material. Here, a PDP which is a representative display device will be described as an example.

  Generally, a PDP has a structure in which a pair of electrodes regularly arranged on two opposing glass substrates are provided, and a gas mainly composed of an inert gas such as Ne or Xe is enclosed between the electrodes. A voltage is applied to the electrodes to generate a discharge in minute cells around the electrodes, thereby causing each cell to emit light and display. These electrodes are covered and protected with an insulating material called a dielectric layer.

  For example, a transparent electrode is formed on a glass substrate that serves as a front plate of an AC type PDP, and a metal electrode such as Ag, Cu, or Al having a lower resistivity is further formed thereon. A dielectric layer is formed to cover the composite electrode, and a protective layer (MgO layer) is further formed thereon.

As the dielectric layer formed to cover the electrodes, a thin film such as SiO ₂ can be formed by a method such as CVD, but usually a glass with a low softening point is used from the viewpoint of equipment and cost. The dielectric layer using the glass having a low softening point is formed by applying a paste containing glass powder so as to cover the electrodes by a screen printing method, a die coating method, or the like, and then baking the paste.

  The characteristics required for the glass composition forming the dielectric layer are: (1) it is formed on the electrode and is therefore insulative; (2) in a large area panel, the warp of the glass substrate, the dielectric In order to prevent peeling and cracking of the layer, the thermal expansion coefficient of the glass composition should be set to a value not much different from that of the substrate material. (3) For the front plate, light generated from the phosphor can be efficiently used. For use as display light, it is an amorphous glass having a high visible light transmittance, and (4) a softening point (softening temperature) is low so as to conform to the heat resistance of the substrate glass. .

As glass substrates used for PDP, there are soda lime glass, which is a window glass made by the float process and is generally easily available, and high strain point glass developed for PDP. These are usually up to 600 ° C. Heat resistance of 75 × 10 ^{−7 to} 85 × 10 ⁻⁷ / ° C.

Therefore, for the above-mentioned (2), the thermal expansion coefficient of ^{60 × 10 -7 ~90 × 10 -7} / ℃ about the glass composition is desirable. In the case of (4) described above, the glass paste must be fired at 600 ° C. or lower, which is the strain point of the glass substrate, so that the softening point is sufficiently softened even when fired at a temperature of 600 ° C. or lower. Is at least 595 ° C. or less, more desirably about 590 ° C. or less.

Currently, PbO—SiO ₂ glass mainly composed of PbO is mainly used as a glass material that satisfies the above demands.

However, in consideration of environmental problems in recent years, a dielectric layer containing no Pb is required, and the dielectric constant of the glass material is required to be further lowered in order to reduce the power consumption of the PDP. ing. As the glass not containing Pb, a Bi ₂ O ₃ —B ₂ O ₃ —ZnO—SiO ₂ glass material (for example, having a low softening point by containing Bi instead of Pb as a main component) Patent Literature 1) and the like have been developed, but these Bi-based materials also have a problem that the relative dielectric constant is as high as about 9 to 13 like the Pb-based materials. Therefore, in order to achieve both a low dielectric constant and a low softening point, a relative dielectric constant of 7 by using a zinc borate glass (alkali metal oxide-B ₂ O ₃ —ZnO—SiO ₂ system) containing an alkali metal instead of Pb. Materials that have achieved back and forth have also been proposed (for example, Patent Documents 2 to 4).
JP 2001-139345 A JP-A-9-278482 JP 2000-313635 A Japanese Patent Laid-Open No. 2002-274883

  However, the lower the desired dielectric constant, the better. However, no glass having a relative dielectric constant of 6.5 or less and a low softening point has been found. In addition, with the alkali zinc borate glasses that have been studied in the past, a glass having a high glass transition point (glass transition temperature) should be realized in addition to satisfying a low softening point and an appropriate thermal expansion coefficient. Was difficult.

  If the glass for simply covering the electrode is sufficient, it is sufficient to realize a low softening point, an appropriate thermal expansion coefficient, and a low dielectric constant. However, in the PDP, after the electrode coating is performed, heat of about 500 ° C. is again applied to the glass layer in an annealing process of the MgO layer or a sealing process for joining the front plate and the back plate. Since the dielectric layer glass has a softening point of slightly less than 600 ° C, it does not soften even when a temperature of about 500 ° C is applied. However, when this heating temperature significantly exceeds the glass transition point, the physical properties of the glass change rapidly. For this reason, particularly in a large-area display, the dielectric layer is peeled off from the substrate or cracks are generated, resulting in a decrease in insulation and reliability. According to the inventor's study, in order to reheat at about 500 ° C., the glass transition point required for glass is preferably 465 ° C. or higher, and more preferably 480 ° C. or higher. Also, in display devices other than PDPs, circuit boards, and the like, if heat treatment is performed again at a high temperature after coating, there is a risk that similar problems will occur.

According to the inventor's study, it is necessary to increase the amount of B ₂ O ₃ in order to lower the dielectric constant in the alkali borate glass, but the glass transition point decreases when the amount of B ₂ O ₃ is increased. There was a trend. In conventional glass for electrode coating, no attention is paid to the glass transition point. Therefore, even if a material having a low softening point, a low dielectric constant, and an appropriate coefficient of thermal expansion is obtained, a high glass is also provided. A material having a transition point has not been obtained.

Furthermore, B in ₂ O ₃ amount of content is large alkali glass, for B ₂ O ₃ is readily soluble in water, there is a problem in that a high low water resistance / moisture resistance. Low water resistance may cause insulation failure due to water splashing on the dielectric layer glass when the substrate is cut, and high hygroscopicity increases the amount of moisture in the system and In some cases, the properties of the MgO protective film formed on the layer deteriorate.

  The present invention can produce a highly reliable display panel with a low softening point, low dielectric constant, good thermal expansion coefficient matching with the substrate, high glass transition point, high water resistance. An object of the present invention is to provide a simple glass composition.

The glass composition of the present invention is an oxide glass, and the ratio of elements other than oxygen (O) among the contained elements is
72 atomic% <boron (B) ≤ 88 atomic%
6 atomic% ≤ R ≤ 16 atomic%
1 atomic% ≦ M ≦ 8 atomic%
0 atomic% ≦ silicon (Si) <12 atomic%
2 atom% <zinc (Zn) ≤ 18 atom%
(Here, R is at least one selected from lithium (Li), sodium (Na), and potassium (K), and M is magnesium (Mg), calcium (Ca), strontium (Sr), barium (Ba 1) or more selected from the above)).

  Moreover, the 1st display panel of this invention is a display panel by which the electrode is coat | covered with the dielectric material layer containing a glass composition, Comprising: This glass composition is the said glass composition by this invention. A second display panel of the present invention is a display panel in which electrodes are covered with a dielectric layer, the dielectric layer directly covering the electrodes, and a first dielectric layer on the first dielectric layer. A glass composition contained in the second dielectric layer, wherein the first dielectric layer is substantially free of alkali metal elements and the second dielectric layer is formed. .

  According to the present invention, a highly reliable display panel having a low softening point, a low dielectric constant, a good thermal expansion coefficient matching with a substrate, a high glass transition point, a high water resistance, and the like. Can be provided.

  As a result of detailed studies, the inventor has found that the softening point is low, the thermal expansion coefficient is well matched with the substrate, and the glass transition point is sufficient in the composition range as described below, despite the extremely low dielectric constant. In addition, the present inventors have found that a glass composition can be obtained, which is high in water resistance and high in water resistance, and which eliminates the disadvantages of conventional zinc borate glasses containing alkali metals.

According to the present invention, the softening point is 595 ° C. or lower, the glass transition point is 465 ° C. or higher, the thermal expansion coefficient is 60 × 10 ⁻⁷ / ° C. to 90 × 10 ⁻⁷ / ° C., and the relative dielectric constant It is possible to obtain a glass composition having a value of 6.5 or less.

(Embodiment 1)
Hereinafter, the reason for limitation of each component in the glass composition of this invention is demonstrated.

  B is a main component of the glass composition of the present invention. The more B, the lower the dielectric constant and the lower the softening point but the lower the glass transition point. What is particularly problematic is that the temperature drop at the glass transition point is larger than the temperature drop at the softening point. As described above, the softening point needs to be 595 ° C. or less, and the glass transition point needs to be 465 ° C. or more. Therefore, the difference between the softening point and the glass transition point is 130 ° C. or less, more desirably 110 ° C. or less. However, the difference increases as B increases. The reason why the amount is limited to more than 72 atomic% and not more than 88 atomic% is that when B is less than 72 atomic%, the dielectric constant increases or the softening point increases, and B exceeds 88 atomic%. This is because if the amount is too large, the glass transition point becomes too low.

  Alkali metals (Li, Na, K) are another main component of the glass composition of the present invention. Increasing the amount of alkali metal has the effect of reducing the difference between the softening point and the glass transition point, but increases the dielectric constant and tends to cause yellowing. The reason why the total amount is 6 atomic% or more and 16 atomic% or less is that if it is less than 6 atomic%, the softening point becomes too high, and if it exceeds 16 atomic%, the dielectric constant and the thermal expansion coefficient become too large. Because.

  Alkaline earth metals (Mg, Ca, Sr, Ba) are essential components of the present invention. Since this invention contains many B, a glass transition point falls and the difference of a softening point and a glass transition point also tends to spread. When a small amount of Mg, Ca, Sr, or Ba is added, the softening point itself is increased, and the glass transition point is further increased. Therefore, there is an effect of increasing the glass transition point and simultaneously reducing the temperature difference from the softening point. A similar effect is also observed in Zn as described later, but the effect of increasing the glass transition point is greater for alkaline earth metals. In addition, when Zn is added, there is a problem that the crystallization temperature decreases due to an increase in the amount of addition, but when adding alkaline earth metal, there is no problem of crystallization, and furthermore, by adding Zn and alkaline earth metal simultaneously. The problem of crystallization caused by the addition of Zn can be avoided. Moreover, although the addition of alkaline earth metal is not as high as Zn, it also has the effect of increasing the water resistance of the glass. Therefore, in order to make a glass having a low dielectric constant / high B amount composition region as in the present application into a practical material, it is essential to add an alkaline earth metal. The reason why the amount is 8 atomic% or less is that when the amount is too large, the softening point becomes high and the dielectric constant becomes too high.

  When the types of alkaline earth metals are compared in the same amount, both the effect of increasing the glass transition point and the effect of reducing the difference between the softening point and the glass transition point are the largest for Ca, the highest dielectric constant is Ba, and Sr, Among these, Ca is the most preferable because it decreases in the order of Ca and Mg.

  Si is not an essential element of the present invention. The inclusion of Si has the effect of increasing the chemical stability of the glass or increasing the glass transition point. However, since the softening point is set higher than the glass transition point, the difference between the softening point and the glass transition point is increased. Accordingly, Si may not be contained at all, but may be contained somewhat for reasons such as improving chemical stability and adjusting the thermal expansion coefficient. The reason why the upper limit is limited to 12 atomic% or less is that when it exceeds 12 atomic%, the softening point becomes too high and the difference between the softening point and the glass transition point is too wide.

  Zn is an essential component of the present invention. The addition of Zn slightly increases the dielectric constant, softening point, and glass transition point, but the effect is less than that of alkaline earth metals when compared with the same addition amount. However, since the increase in the softening point is small compared to the increase in the glass transition point and the effect of increasing the dielectric constant and the softening point is small, it can be used in a relatively large amount. The effect of reducing the difference is greater than that of alkaline earth metals. Further, the addition of Zn has an effect of improving water resistance even with a small amount. The reason for limiting the amount to more than 2 atomic% is that it is insufficient for imparting water resistance if it is 2 atomic% or less, and the reason for setting it to 18 atomic% or less is that the softening point becomes too high if it exceeds 18 atomic%. Because.

  By setting it as the above composition range, a glass material having good characteristics can be obtained. Furthermore, in order to further improve the characteristics, elements such as B and Si, which are glass network-forming oxides (this is A group element), alkali metals, alkaline earth metals, Zn, etc. It is important that the atomic ratio of an element (this is a group B element) that becomes a network-modifying oxide of glass is within a specific range as described below.

  B and Si belonging to the A group both lower the dielectric constant, but B has the effect of widening the difference between the two while lowering the softening point and the glass transition point, and Si increases the softening point and the glass transition point. However, it has the effect of widening the difference between the two. Therefore, in order to achieve both a low softening point and a low dielectric constant, it is sufficient to increase B, but the difference between the softening point and the glass transition point widens. On the other hand, elements belonging to Group B have the effect of reducing the difference between the softening point and the glass transition point, to some extent.

  For this reason, in order to simultaneously realize a low dielectric constant, a low softening point, and a high glass transition point, the atomic ratio of the A group element and the B group element is important. When the total of the% of each element of A group and B group is set to X and Y, X / Y will be about 2.6-10 in said composition range, More desirably, it is 3.0 or more and 5. 0 or less. This is because, within the range of atomic% of each of the above components and when X / Y is 3.0 or more and 5.0 or less, the relative dielectric constant is 6.0 or less and the difference between the softening point and the glass transition point is 110 ° C. This is because it can be as follows.

  The glass composition of the present invention contains the above components, and typically consists essentially of the above components (in other words, the components other than the above components may not be substantially contained), but the effects of the present invention are obtained. Other components may be contained as long as possible. The total content of other components is preferably 5 atomic percent or less, more preferably 3 atomic percent or less, and even more preferably 1 atomic percent or less.

  Specific examples of other components include rare earth metals such as yttrium (Y) and lanthanum (La), bismuth (Bi), vanadium (V), antimony (Sb), phosphorus (P), molybdenum (Mo), tungsten ( W), titanium (Ti), cobalt (Co), and copper (Cu). Rare earth metals such as yttrium (Y) and lanthanum (La) increase the glass transition point by about 10 to 20 ° C., but also increase the softening point to the same extent. Therefore, when the glass transition point and softening point of the basic composition are low. , This can be high. Bismuth (Bi), vanadium (V), antimony (Sb), phosphorus (P) lowers the glass transition point by about 10 to 20 ° C., but also lowers the softening point to the same extent. This can be reduced if the softening point is high. Molybdenum (Mo) and tungsten (W) have an effect of suppressing the occurrence of yellowing. Titanium (Ti), cobalt (Co), and copper (Cu) color the glass blue. Therefore, when yellowing occurs, the color balance can be prevented from being lost by the complementary blue color. The desirable upper limit of these additives is 5 atomic percent or less, more preferably 3 atomic percent or less, and even more preferably 1 atomic percent or less, as described above. This is because the dielectric constant increases, the raw material cost increases.

  Besides these, a small amount of Al, Zr, Mn, Nb, Ta, Te, Ag, etc. may be added to adjust the thermal expansion coefficient, stabilize the glass, and improve chemical durability. If possible. Also about these, Preferably it is 5 atomic% or less, More preferably, it is 3 atomic% or less, More preferably, it is 1 atomic% or less.

  It is preferable that the glass composition of the present invention does not substantially contain lead (Pb). This is because the addition of Pb may cause problems such as effects on the environment, increase in dielectric constant, coloring of glass, and increase in raw material cost.

  Since the glass composition of the present invention contains an alkali metal as a component, when used as a dielectric material for protecting Ag and Cu, depending on the firing conditions, Ag and Cu are oxidized and ionized. The problem of spreading inside can occur. Ag and Cu ions are reduced again and deposited as colloidal metal, causing a so-called yellowing in which the dielectric layer and the glass substrate appear to be colored yellow. When yellowing occurs, the display performance deteriorates particularly when used as a dielectric layer for a front panel of a PDP. In this case, if the glass composition of the present invention is used as a second dielectric layer laminated on the first dielectric layer that is in direct contact with the electrode, the layer substantially free of alkali metal is used as a whole. Yellowing can be prevented while keeping the dielectric constant low.

  In the present specification, “substantially free” means, as described above, a very small amount of a component that is industrially difficult to remove and does not affect properties in the ratio of elements excluding oxygen (O). Specifically, it means that the content is 1 atomic% or less, more preferably 0.1 atomic% or less.

Note that in this specification, the ratio of elements is expressed as a ratio of only cations, but since it is an oxide glass, oxygen exists as anions in the glass. When the above cations are expressed by unit oxides as usual, B ₂ O ₃ , SiO ₂ , ZnO, K ₂ O, Na ₂ O, Li ₂ O, MgO, CaO, SrO, BaO are obtained. . However, such notation does not limit the valence of each cation in the glass.

In addition, the glass composition ratio is expressed by the weight percentage of the oxide as described above. For example, Li, Na, and K give similar contributions to the characteristics of the glass as an alkali metal. It may be written. However, since the number of atoms contained in Li and K is completely different even at the same weight%, it is essentially not appropriate to describe each component ratio in weight%. Although it may be expressed in terms of mol% of the oxide, for example, K ₂ O = 20 mol%, ZnO = 20 mol%, B ₂ O ₃ = 60 mol%, K ₂ O = 10 mol%, ZnO = 30 mol% When B ₂ O ₃ = 60 mol%, B ₂ O ₃ is the same 60 mol%, but the number of B atoms contained in the glass is not the same, so it is difficult to say that this mol% notation is desirable. It is for this reason that this application describes in atomic%.

For convenience, claim 1 of this application is expressed in terms of weight percent,
52 wt% <boron (B) ≤ 90 wt%
2 wt% ≤ R ≤ 19 wt%
1 wt% ≤ M ≤ 29 wt%
0 wt% ≤ silicon (Si) ≤ 20 wt%
3.5% by weight <zinc (Zn) ≦ 35% by weight
It becomes. In particular, in R and M, the upper and lower limits are wider than the original atomic% display because the R and M elements have a range of atomic weights.

However, the most desirable as R is K which hardly causes yellowing, and the most desirable as M is Ca for the reason described above. Therefore, considering this point, a more desirable range is described in wt%. Then
60% by weight <boron (B) ≦ 85% by weight
6 wt% ≤ R ≤ 19 wt%
1 wt% ≤ M ≤ 12 wt%
0 wt% ≤ silicon (Si) ≤ 19 wt%
3.5% by weight <zinc (Zn) ≦ 34% by weight
It becomes.

  Similarly, in claim 2, zinc (Zn) is preferably in the range of more than 15% by weight and 34% by weight or less.

(PDP configuration)
A PDP will be described as a specific example of the display panel of the present invention. FIG. 1 is a partially cutaway perspective view showing the main configuration of the PDP according to the present embodiment. FIG. 2 is a cross-sectional view of this PDP. This PDP is an AC surface discharge type, and has the same configuration as that of the conventional PDP except that the dielectric layer is formed of the glass composition described above.

  This PDP is configured by bonding a front plate 1 and a back plate 8 together. The front plate 1 is formed so as to cover the front glass substrate 2, the display electrode 5 composed of the transparent electrode 3 and the bus electrode 4 formed on the inner side surface (surface facing the discharge space 14), and the display electrode 5. A dielectric layer 6 and a dielectric protective layer 7 made of magnesium oxide and formed on the dielectric layer 6 are provided. The display electrode 5 is formed by laminating a bus electrode 4 made of Ag or the like on the transparent electrode 3 made of ITO or tin oxide in order to ensure good conductivity.

  The back plate 8 includes a back glass substrate 9, an address electrode 10 formed on the inner surface thereof, a dielectric layer 11 formed so as to cover the address electrode 10, and a partition wall 12 provided on the top surface of the dielectric layer 11. And a phosphor layer 13 formed between the barrier ribs 12. The phosphor layer 13 is formed so that the red phosphor layer 13 (R), the green phosphor layer 13 (G), and the blue phosphor layer 13 (B) are arranged in this order.

  For the dielectric layer 6 and / or the dielectric layer 11, preferably the dielectric layer 6, the glass composition according to the present invention described above is used.

As the phosphor constituting the phosphor layer 13, for example, BaMgAl ₁₀ O ₁₇ : Eu is used as a blue phosphor, Zn ₂ SiO ₄ : Mn is used as a green phosphor, and Y ₂ O ₃ : Eu is used as a red phosphor. Can do.

  The front plate 1 and the back plate 8 are arranged so that the longitudinal directions of the display electrodes 5 and the address electrodes 10 are orthogonal to each other and face each other, and are joined using a sealing member (not shown).

  In the discharge space 14, a discharge gas (filled gas) made of a rare gas component such as He, Xe, or Ne is sealed at a pressure of about 66.5 to 79.8 kPa (500 to 600 Torr).

  The display electrode 5 and the address electrode 10 are each connected to an external drive circuit (not shown), and a discharge is generated in the discharge space 14 by a voltage applied from the drive circuit, and a short wavelength (wavelength generated by the discharge). The phosphor layer 13 is excited by ultraviolet rays of 147 nm and emits visible light.

  The dielectric layer 6 is usually made into a glass paste by adding a binder, a solvent or the like for imparting printability to the glass powder, and this glass paste is applied and fired on an electrode formed on a glass substrate. Formed by.

  Glass paste contains glass powder, solvent and resin (binder), but other components such as surfactant, development accelerator, adhesion aid, antihalation agent, storage stabilizer, antifoaming agent, You may include the additive according to various objectives, such as antioxidant, a ultraviolet absorber, a pigment, dye.

  The kind of resin (binder) contained in the glass paste is not particularly limited as long as the reactivity with the raw material powder is low. From the viewpoints of chemical stability, cost and safety, for example, cellulose derivatives such as nitrocellulose, methylcellulose, ethylcellulose and carboxymethylcellulose, polyvinyl alcohol, polyvinyl butyral, polyethylene fglycol, carbonate resins, urethane resins, acrylic resins At least one selected from resins and melamine resins can be used.

  The kind of the solvent contained in the glass paste is not particularly limited as long as the reactivity with the raw material powder is low. From the viewpoints of chemical stability, cost and safety, and compatibility with the binder, for example, ethylene glycol monoalkyl ethers, ethylene glycol monoalkyl ether acetates, diethylene glycol dialkyl ethers, propylene glycol monoalkyl Organic solvents such as ethers, propylene glycol dialkyl ethers, propylene glycol alkyl ether acetates, esters of aliphatic carboxylic acids, and alcohols such as terpineol and benzyl alcohol can be used.

  Typically, the glass paste is applied by a screen method, a bar coater, a roll coater, a die coater, a doctor blade or the like, and baked. However, without being limited thereto, for example, it can be formed by a method of attaching and baking a sheet containing the glass composition.

  The thickness of the dielectric layer 6 is preferably about 10 μm to 50 μm in order to achieve both insulation and light transmittance.

  Next, a PDP having a two-layer dielectric layer will be described with reference to FIG. FIG. 3 is a cross-sectional view of a PDP in which the dielectric layer on the front plate has a two-layer structure. Instead of the dielectric layer 6, a two-layer structure of a first dielectric layer 15 and a second dielectric layer 16 is shown. 2 is the same as the PDP in FIG. 2 except that the same dielectric layer is used (the same members (films) are denoted by the same reference numerals and description thereof is omitted).

  As shown in FIG. 3, the first dielectric layer 15 covers the display electrode 5, and the second dielectric layer 16 is disposed to cover the first dielectric layer 15. Thus, when the dielectric layer has a two-layer structure, the glass composition contained in the second dielectric layer 16 is the glass composition of the present invention, and the first dielectric layer 15 substantially contains an alkali metal element. It is preferable to have no layer. Since the first dielectric layer 15 that is in direct contact with the display electrode 5 does not substantially contain an alkali metal element, at least the first dielectric layer 15 is yellowed due to colloidal deposition of Ag or Cu, and the breakdown voltage is reduced. Can be prevented. Moreover, since the diffusion of Ag or Cu ions is suppressed in the first dielectric layer 15, the second dielectric layer 16 can also be prevented from being discolored or having a reduced withstand voltage.

  According to the glass composition of the present invention, a glass composition having a relative dielectric constant of 6.5 or less can be provided. If this glass composition is used for the second dielectric layer 16, even if a material having a slightly higher dielectric constant is used for the first dielectric layer 15, a dielectric layer having a low dielectric constant as a whole can be formed. Considering that the relative permittivity of conventional Pb-based glass and Bi-based glass is 9 to 13, the power consumption can be reduced even with the above two-layer configuration.

  The dielectric layer having the two-layer structure can be formed by applying the glass composition for the second dielectric layer 16 after the first dielectric layer 15 is formed, and baking it. When a glass composition is used for the dielectric layer 15, the glass layer preferably has a softening point higher than the softening point of the glass composition contained in the second dielectric layer 16.

  In order to ensure insulation between the transparent electrode 3 and the bus electrode 4 and the second dielectric layer 16 and prevention of an interface reaction, the film thickness of the first dielectric layer 15 is preferably 1 μm or more.

  In order to achieve both insulation and transmittance, it is preferable that the total film thickness of the first dielectric layer 15 and the second dielectric layer 16 be about 10 μm to 50 μm.

(Production method of PDP)
A method for manufacturing the PDP will be described with an example. First, the front plate 1 is produced. A plurality of line-shaped transparent electrodes 3 made of ITO or tin oxide are formed on one main surface of the flat front glass substrate 2. Subsequently, after applying the silver paste on the transparent electrode 3, the silver paste is fired by heating the entire front glass substrate 2 to form the display electrode 5.

  A glass paste containing the glass composition of the present invention as a dielectric layer 6 is applied to the main surface of the front glass substrate 2 by a blade coater method so as to cover the display electrode 5. Thereafter, the entire front glass substrate 2 is held at 90 ° C. for 30 minutes to dry the glass paste, and then baked at a temperature of about 580 ° C. for 10 minutes.

  A film of magnesium oxide (MgO) is formed on the dielectric layer 6 by an electron beam evaporation method, and baked to form the dielectric protective layer 7. The firing temperature at this time is around 500 ° C.

  As shown in FIG. 3, in the method for manufacturing a PDP having a dielectric layer having a two-layer structure, a first dielectric layer 15 is formed so as to cover the display electrode 5 and the first dielectric is formed. A glass paste for the second dielectric layer 16 is applied on the body layer 15, dried and fired to form the second dielectric layer 16.

  Next, the back plate 8 is produced. After applying a plurality of silver pastes in a line shape on one main surface of the flat back glass substrate 9, the back glass substrate 9 is heated and baked to form the address electrodes 10.

  A partition wall 12 is formed by applying a glass paste on the dielectric layer 11 between the adjacent address electrodes 10 and heating the entire back glass substrate 9 to fire the glass paste.

  By applying phosphor inks of R, G, and B colors between adjacent barrier ribs 12 and heating the entire back glass substrate 9 to about 500 ° C. and firing the phosphor ink, The phosphor layer 13 is formed by removing the resin component (binder) and the like.

  The front plate 1 and the back plate 8 thus obtained are bonded together using sealing glass. The temperature at this time is around 500 ° C. Thereafter, after the sealed interior is evacuated to high vacuum, a rare gas is sealed. A PDP is obtained as described above.

  The above-mentioned PDP and its manufacturing method are merely examples, and the present invention is not limited to this. However, as described above, the dielectric layer is not only fired itself, but also firing of the MgO layer and sealing of the front plate and the back plate. At the time of wearing, heat treatment at about 500 ° C. is performed for a short time. At this time, if the glass transition point of the dielectric layer is too low, the coefficient of thermal expansion becomes large in the temperature range exceeding the glass transition point, so that the dielectric layer is cracked or peeled off and cannot be used. According to the inventors' investigation, the glass transition point of the glass composition contained in the dielectric layer is preferably 465 ° C. or higher, and more preferably 480 ° C. or higher.

  The PDP to which the present invention is applied is typically a surface discharge type as described above, but is not limited to this and can also be applied to a counter discharge type. Further, the present invention is not limited to the AC type, and can be applied to a DC type PDP having a dielectric layer.

  The glass composition of the present invention is not limited to the PDP, and can be effectively used for a display panel that needs to be subjected to a high-temperature heat treatment at about 500 ° C. again after the heat treatment for forming the glass layer.

  The glass composition of the present invention is suitable for a display panel in which the electrode covered with the dielectric layer contains at least one selected from Ag and Cu. The electrode may be mainly composed of Ag.

  Hereinafter, the present invention will be described in more detail with reference to examples.

Example 1
As starting materials, oxides or carbonates of various kinds of metals of reagent grade or better were used. These raw materials were weighed so that the atomic ratio of each element was as shown in (Table 1), mixed well, put into a platinum crucible, and melted in an electric furnace at 900 to 1100 ° C. for 2 hours. The obtained melt was quenched by pressing with a brass plate to produce a glass cullet. The glass cullet was pulverized, and the softening point Ts and the peak temperature of crystallization exotherm (= crystallization start temperature) Tx were measured using a macro type differential thermal analyzer.

Next, the glass cullet was remelted to form a 4 mm × 4 mm × 20 mm glass rod, and the glass transition point Tg and the thermal expansion coefficient α were measured using a thermomechanical analyzer. Further, the glass cullet was remelted to form a 20 mm × 20 mm × 1 mm plate, the surface was mirror-polished, electrodes were deposited, and the relative dielectric constant ε was measured at a frequency of 1 kHz using an LCR meter. . Further, the glass cullet is remelted to prepare a block of 20 mm × 10 mm × 5 mm, this block is immersed in hot water at 80 ° C. for 24 hours, and the volume dissolved from the weight change before and after the immersion is calculated. Was dissolved by the surface area of the sample before immersion, and the dissolved thickness (= dissolved amount) Δt was measured. The measurement results are shown in (Table 1). In all the tables below, the unit of glass transition point Tg, softening point Ts, peak temperature (= crystallization start temperature) Tx is ° C., the unit of thermal expansion coefficient α is × 10 ⁻⁷ / ° C., dissolution amount Δt The unit of is μm.

  As is clear from Table 1, sample No. consisting only of B and K No. 1 has a very low relative dielectric constant ε, but both the glass transition point Tg and the softening point Ts are low, and Ts−Tg is 137 ° C. Moreover, there was no water resistance and it melt | dissolved completely. This sample No. 1, sample No. 1 in which Zn, Mg, Ca, Sr, and Ba were added alone, respectively. In 2-16, with addition, both the glass transition point Tg and the softening point Ts increased, Ts-Tg also decreased, and the water resistance also improved. However, a large amount of addition is necessary to sufficiently increase the glass transition point Tg by addition of Zn. As shown in FIG. 4, there is a problem that the crystallization start temperature Tx is lowered (with respect to the crystallization start temperature Tx, since a very small amount of crystals are generated at a temperature considerably lower than the exothermic peak, If the difference in softening point Ts is 50 ° C. or less, there is a risk that a small amount of crystals are mixed in the glass layer after firing and the transmittance is lowered, which causes a problem in actual use). In addition, when the alkaline earth was added, the glass transition point Tg and softening point Ts increased and the crystallization start temperature Tx increased with a relatively small amount, but Ts−Tg was 120 ° C. or higher, and the dissolution amount Δt. Exceeded 100 μm, and both showed uneasy results in actual use.

  On the other hand, sample No. 1 using both Zn and alkaline earth. 17 to 23, the glass transition point Tg and the softening point Ts can be set to appropriate values in the range where the relative dielectric constant ε is 6.0 or less, there is no problem of crystallization, and the dissolution amount Δt is also about 20 μm. And there were few. No. In 24, the amount of B was small and the softening point Ts was high.

  Sample No. with more or less B In 25-31, when the amount of B exceeded 88 mol%, the glass transition point Tg was too low, and at 72 mol%, the softening point Ts was too high. No. Together with the results of 17 to 24, it was found that the amount of B needs to be over 72 mol% and 88 mol% or less.

  Sample No. with fixed Zn content and increased Ca content. In 32 to 35, when Ca exceeded 8 mol%, the softening point Ts was high, and the relative dielectric constant ε was too large.

  Sample No. with different types of alkaline earth Both 33 and 36 to 38 showed good results, but Ca had the smallest difference between the glass transition point Tg and the softening point Ts, and the dielectric constant ε was also low and good. In addition, No. 4 used in combination with four alkaline earths. In 39, average characteristics were obtained.

(Example 2)
A glass cullet and a glass rod in which the atomic ratio of each metal element is (Table 2) are prepared in the same manner as in Example 1, and the glass transition point Tg, softening point Ts, crystal are produced in the same manner as in Example 1. The initiation temperature Tx, thermal expansion coefficient α, relative dielectric constant ε, and dissolution amount Δt were measured. In all samples, the crystallization start temperature Tx exceeded 700 ° C., and the dissolution amount Δt was less than 20 μm. The other measurement results are shown in Table 2.

  No. which increased K amount and decreased B amount. In 41 to 45, the softening point Ts was too high when the K amount was small, and the relative dielectric constant ε was high when the K amount was large.

  Sample No. 8 was replaced by Na or Li to make 6 atomic% or 16 atomic%. In 46 to 49, at the same addition amount, the softening point Ts was Li <Na <K, the thermal expansion coefficient α was Li <Na <K, and the relative dielectric constant ε was Li> Na> K. Was not seen. In addition, sample No. using Li, Na, and K together. In 50, it became an average characteristic. Therefore, the amount of Li + Na + K is desirably 6 atomic% or more and 16 atomic% or less.

  Sample No. which had increased Si amount with respect to other components. In 51-56, the softening point Ts rose with the addition amount increase. Therefore, Si needs to be 12 atomic% or less, more desirably 10 atomic% or less, and further desirably 5 atomic% or less.

The inventor examined combinations of various compositions other than those shown in Examples 1 and 2 above, but in any case, 72 atomic% <B ≦ 88 atomic%, 6 atomic% ≦ Li + Na + K ≦ 16 atoms. %, 1 atomic% ≦ Mg + Ca + Sr + Ba ≦ 8 atomic%, 0 atomic% ≦ Si ≦ 12 atomic%, 2 atomic% <Zn ≦ 18 atomic%, by adjusting the composition, a relative dielectric constant of 6.5 or less, A glass having a glass transition point of 465 ° C. or more, a softening point of 595 ° C. or less, a thermal expansion coefficient of 60 × 10 ^{−7 to} 90 × 10 ⁻⁷ / ° C., and a glass having good characteristics with a melt thickness of 100 μm or less. Was possible. Moreover, it was possible to make a glass transition point 480 degreeC or more by making Zn amount 7 atomic% or more, more desirably 7.5 atomic% or more.

(Example 3)
In the same manner as in Example 1, various raw material powders were mixed and placed in a platinum crucible so that the atomic ratio of B: K: Ca: Zn = 80.5: 10: 2: 7.5 was obtained. After melting at 1150 ° C. for 2 hours, a glass cullet was produced by a twin roller method. The glass cullet was pulverized by a dry ball mill to produce a powder. The average particle size of the obtained glass powder was about 5 μm. The relative dielectric constant of the present glass was 5.7, the glass transition point was 485 ° C., the softening point was 582 ° C., and the thermal expansion coefficient was 72 × 10 ⁻⁷ / ° C.

  To this powder, ethyl cellulose as a binder and α-terpineol as a solvent were added and mixed with three rolls to obtain a glass paste.

  Next, an ITO (transparent electrode) material was applied in a predetermined pattern on the surface of a front glass substrate made of flat soda-lime glass having a thickness of about 2.8 mm and dried. Next, a plurality of silver pastes, which are a mixture of silver powder and an organic vehicle, were applied in a line shape, and then the front glass substrate was heated, whereby the silver paste was baked to form display electrodes.

  The glass paste mentioned above was apply | coated to the front glass substrate which produced the display electrode using the blade coater method. Thereafter, the front glass substrate was held at 90 ° C. for 30 minutes to dry the glass paste, and baked at a temperature of 585 ° C. for 10 minutes to form a dielectric layer having a thickness of about 30 μm.

  Magnesium oxide (MgO) was deposited on the dielectric layer by an electron beam deposition method, and then baked at 500 ° C. to form a protective layer.

  On the other hand, a back plate was produced by the following method. First, an address electrode mainly composed of silver was formed in a stripe shape on a rear glass substrate made of soda lime glass by screen printing, and then a dielectric layer having a thickness of about 8 μm was formed in the same manner as the front plate. .

  Next, partition walls were formed on the dielectric layer using glass paste between adjacent address electrodes. The partition was formed by repeating screen printing and baking.

  Subsequently, the phosphor layer of red (R), green (G), and blue (B) is applied to the surface of the dielectric layer exposed between the wall surfaces of the barrier ribs and the barrier ribs, and then dried and fired to phosphor layer Was made. The materials described above were used as the phosphor.

The produced front plate and back plate were bonded at 500 ° C. using a Bi—Zn—B—Si—O-based sealing glass. Then, after the inside of the discharge space was evacuated to a high vacuum (1 × 10 ⁻⁴ Pa), Ne—Xe-based discharge gas was sealed so as to have a predetermined pressure. In this way, a PDP was produced.

  It was confirmed that the fabricated panel operated without any problem without causing any defects in the dielectric layer.

Example 4
Similarly to Example 3, a BK—Ca—Zn—O-based glass paste was prepared for the second dielectric layer. Separately, for the first dielectric layer, Bi—Zn—B—Ca—Si—O-based glass containing Bi, substantially free of alkali metal, having a relative dielectric constant of 11 and a softening point of 587 ° C. A paste was prepared.

  Using these pastes, in the same manner as in Example 3, the dielectric layer of the front plate directly covers the electrodes, and the second dielectric formed on the first dielectric layer. A PDP panel having a two-layer structure of body layers was prepared. The first dielectric layer was fired at 590 ° C. to a thickness of about 10 μm, and the second dielectric layer was fired at 580 ° C. to a thickness of about 20 μm.

  It was confirmed that the fabricated panel operated without any problem without causing any defects in the dielectric layer.

  The present invention can be suitably applied to the formation of a dielectric layer for covering insulating coating glass for electrodes, particularly display electrodes and address electrodes of plasma display panels.

The partial cutaway perspective view which shows an example of the structure of PDP by this invention Cross-sectional view of the PDP shown in FIG. Sectional drawing which shows another example of a structure of PDP by this invention

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Front plate 2 Front glass substrate 3 Transparent electrode 4 Bus electrode 5 Display electrode 6 Dielectric layer 7 Dielectric protective layer 8 Back plate 9 Back glass substrate 10 Address electrode 11 Dielectric layer 12 Partition 13 Phosphor layer 14 Discharge space 15 1st 1 dielectric layer 16 2nd dielectric layer

Claims (6)

It is an oxide glass, and the ratio of elements excluding oxygen (O) among the contained elements is
72 atomic% <boron (B) ≤ 88 atomic%
6 atomic% ≤ R ≤ 16 atomic%
1 atomic% ≦ M ≦ 8 atomic%
0 atomic% ≤ silicon (Si) ≤ 12 atomic%
2 atom% <zinc (Zn) ≤ 18 atom%
(Wherein R is one or more selected from Li, Na and K, and M is one or more selected from Mg, Ca, Sr and Ba). The glass composition according to claim 1, wherein zinc (Zn) is more than 7 atomic% and not more than 18 atomic%. The softening point is 595 ° C. or lower, the glass transition point is 465 ° C. or higher, the thermal expansion coefficient is 60 × 10 ⁻⁷ / ° C. to 90 × 10 ⁻⁷ / ° C., and the relative dielectric constant is 6.5 or lower. The glass composition according to claim 1 or 2. The display panel by which the electrode is coat | covered with the dielectric material layer containing a glass composition, Comprising: The said glass composition is a glass panel in any one of Claims 1-3. A display panel in which electrodes are covered with a dielectric layer, wherein the dielectric layer directly covers the electrodes, and a second dielectric layer formed on the first dielectric layer A display panel, wherein the first dielectric layer is substantially free of alkali metal elements, and the second dielectric layer is the glass composition according to claim 1. The display panel according to claim 4, wherein the electrode includes at least one selected from silver (Ag) and copper (Cu).

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