JP2006290683A - Dielectric film and method for manufacturing the same - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a method for manufacturing a dense dielectric film to be laminated on a glass substrate for a display panel without causing warpage in the substrate, and a method for manufacturing a dielectric film by using a glass composition free of harmful matter such as lead and small in environmental load. <P>SOLUTION: This dielectric film has two or more dielectric layers capable of suppressing warpage of the glass substrate. A lowermost layer (A) of the dielectric layers is formed of a glass composition comprising, in terms of oxides, 1-15 mol% SiO<SB>2</SB>, 10-50 mol% B<SB>2</SB>O<SB>3</SB>, 30-50 mol% ZnO and 0-12 mol% alkali metal oxide expressed by general formula: R<SB>2</SB>O (R represents at least one alkali metal element selected from K, Na and Li), and has a glass transition temperature of 480-540°C. On the other hand, the glass transition temperature of the glass composition forming a dielectric layer (B) provided on the lowermost layer is 430-480°C. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a dielectric film and a method of manufacturing the same, and more particularly, a dense dielectric film that is laminated without causing warpage on a glass substrate for a display panel, and an environmental load that does not contain harmful substances such as lead. The present invention relates to a method for manufacturing a dielectric film using a glass composition having a small size.

  A display panel, for example, a plasma display panel (hereinafter referred to as PDP) has been spotlighted as a large flat display, has been put into practical use as a large television receiver, and has begun to spread rapidly. A fluorescent display tube (hereinafter referred to as VFD) is used as a display device for measuring instruments such as automobiles, audio equipment, and digital multimeters as a display device for characters and symbols, and a field emission display (hereinafter referred to as FED). ) Is expected as a future display device to replace CRT.

A PDP is a pair of glass plates facing each other with a slight gap and sealed around the bottom so that a discharge space having a phosphor is obtained at the bottom. Can be projected. A glass plate on the side where an image is displayed on the PDP is called a front plate, and the other is called a back plate. A back plate of a general AC type PDP has a structure as shown in FIG.
Striped partition walls 16 are formed on the back plate 10b, and one electrode 13 (also referred to as an address electrode) is formed in parallel with the partition walls on the bottom surfaces of the recesses of the partition walls 16, and a dielectric is formed on the surface of the electrodes. Layer 15 is formed and covers the electrodes. The wall surfaces of the partition walls 16 are coated with a phosphor 17 that emits light when irradiated with ultraviolet rays.
The front plate 10a is provided with a transparent electrode 11 made of striped ITO or the like and transmitting visible light, and a bus electrode 12 made of one silver or the like provided on the transparent electrode. A dielectric film 15 made of glass or the like is formed so as to cover this electrode, and an MgO film 14 is formed by vapor deposition so as to cover this dielectric film. In order to form a PDP having such a structure, an existing thick film technique is used for electrodes, dielectrics, partitions, and the like formed of silver.

On the other hand, a general VFD has a vacuum vessel composed of a face glass 21 and a glass substrate 22 as shown in FIG. 3, and the electrons emitted from the filament 26 in the vacuum vessel are controlled by a lattice electrode 23 and are segmented. By colliding with the electrode 24, the fluorescent substance on the segment electrode 24 is stimulated to emit light to display characters, symbols, and the like. A segment electrode serving as a display portion is formed on the glass substrate, and a wiring 27 that transmits a signal to the electrode and an insulating layer 25 that insulates between the wiring 27 and the segment electrode 24 are disposed.
Thick film technology is often used to form electrodes and insulators on glass substrates, and the wiring to segment electrodes is often formed with thick film silver paste. The segment electrode is formed of a thick film paste mainly composed of graphite. Note that the insulating layer is printed so as to form a through-hole in order to ensure conduction between the segment electrode and the wiring.

  On the other hand, the FED shown in FIG. 4 forms an electron-emitting device 36 that emits electrons on one glass substrate 31b of a vacuum container composed of two opposing glass substrates 31, and the emitted electrons. Is made to collide with the phosphor 33 of the other glass substrate 31a to emit stimulating light. A glass substrate 31b on which the electron-emitting device 36 is formed has a wiring 38 for sending a signal to the electron-emitting device 36, a dielectric 37 covering the wiring 38, and a gate electrode 34 provided on the spacer 35. Is formed. The electron-emitting device 36 is provided at a place where the spacer 35 is not provided. In order to increase the mechanical strength of the VFD vacuum vessel composed of a glass substrate or the like, a pillar-shaped structure formed of a dielectric material or the like is provided between two glass substrates (not shown). There is. Each component of the FED is formed by using thin film technology, while the dielectric is formed by thick film technology.

Since these PDP, VFD, and FED use high strain point glass (for example, PD-200 manufactured by Asahi Glass Co., Ltd.) or soda lime glass as a substrate, the firing temperature is limited to 600 ° C. at the highest. Therefore, a dense fired film cannot be obtained unless the softening point of the glass is lower than this temperature.
Conventional glass has realized this softening point by containing lead and bismuth. Patent Documents 1 and 2 disclose glass containing lead, and Patent Document 3 discloses glass containing bismuth. If the conventional glass containing lead which is a harmful substance is used, the dielectric of the obtained thick film glass paste does not warp the substrate by firing.

  However, these lead and bismuth contained in glass are released into the global environment as waste when the display device is discarded, as well as when manufacturing the display device, causing contamination, pollution, etc. of soil, groundwater, rivers, etc. It will cause environmental problems.

  In order to solve this problem, Patent Documents 4 and 5 disclose glass containing P. However, glass containing P has a problem in water resistance and has difficulty in practical use. Patent Documents 3 and 6 to 10 disclose the composition of B-Si-Zn glass.

However, when such lead-free glass is used, the substrate of the thick film glass paste obtained may be greatly warped when fired. In particular, in a dielectric that forms a glass film over the entire surface of the substrate, the warpage of the substrate becomes significant. If the substrate is warped, when assembling the device, it becomes impossible to seal in the sealing process, so a vacuum container cannot be obtained, and as a result, there is a problem that the device cannot be obtained and a problem in ensuring accuracy. Will occur.
Therefore, in patent document 10, in order to prevent a deformation | transformation of a glass substrate, it is supposed that the partition wall formation material for PDP will be baked at 600 degrees C or less. However, no consideration is given to the constituent components of the glass composition used therefor.

  Such deformation of the glass substrate is assumed to occur because volume shrinkage occurs in the partition walls after firing due to the disappearance of the binder and melting of the low melting glass accompanying the firing process. When the back panel is overlapped, the discharge space section becomes insufficient due to the warping of the end of the barrier rib, and the discharge in a given discharge cell spreads to the adjacent discharge space to the adjacent discharge cell. It is supposed to cause false discharge (interference of discharge occurs). This document mainly describes measures from the viewpoint of device design, such as limiting the place where the dielectric layer is formed, and does not mention improvement of the glass composition itself.

Under these circumstances, when a dielectric is formed by applying a glass paste containing glass that does not contain harmful substances such as lead and bismuth onto a glass substrate for a display such as PDP, the substrate is warped during the firing process. There is a need for a dielectric that can assemble a device that ensures accuracy while substantially suppressing the above, and a glass composition suitable for its production.
JP-A-8-119725 JP 11-60273 A JP-A-9-283035 JP-A-8-301631 JP 2000-128567 A JP-A-9-278482 JP 2000-226231 A JP 2000-226232 A JP 2000-313635 A JP 2000-327370 A JP 2001-319580 A

  In view of the above-mentioned conventional problems, the object of the present invention is a dense dielectric film that is laminated without causing warpage on a glass substrate for a display panel, and a glass composition that does not contain harmful substances such as lead and has a low environmental load. An object of the present invention is to provide a method of manufacturing a dielectric film using an object.

  As a result of intensive research in order to solve the above problems, the present inventors have found that in a dielectric film laminated on a glass substrate such as PDP using a glass composition containing no lead or bismuth, a glass paste By forming at least two dielectric layers so that the glass substrate does not warp in the process of applying and baking, and forming the lowermost layer (glass substrate side) using a specific glass composition, The present inventors have found that a dielectric film that can not only substantially suppress warpage of the glass substrate but also has a dense and excellent withstand voltage characteristic can be obtained, and the present invention has been completed.

That is, according to the first invention of the present invention, there is provided a dielectric film having two or more dielectric layers capable of suppressing the warpage of the glass substrate without substantially containing lead or bismuth, lowermost dielectric layer provided on the substrate (a) is in terms of oxide, the _{SiO 2 1~15mol%, B 2 O} 3 and 10-50 mol%, 30 to 50 mol% of ZnO, and the general formula: It is formed from a glass composition containing 0 to 12 mol% of an alkali metal oxide represented by R ₂ O (wherein R represents at least one alkali metal element selected from K, Na, or Li). And the glass transition point is 480 degreeC-540 degreeC, on the other hand, the glass transition point of the glass composition which forms the dielectric material layer (B) provided on the lowest layer is 430 degreeC-480 degreeC. A dielectric film characterized by It is subjected.

  According to the second invention of the present invention, in the first invention, the glass composition forming the dielectric layer (A) is further selected from BaO, CaO or Sr0 in terms of oxide. A dielectric film comprising 1 to 35 mol% of an alkaline earth metal oxide is provided.

  On the other hand, according to the third invention of the present invention, in the first invention, the glass composition forming the dielectric layer (A) is further composed of alumina, silica, forsterite, zirconia, zircon, titania or heat resistant inorganic. There is provided a dielectric film characterized in that it contains 5 to 20% by weight of at least one inorganic oxide powder selected from pigments based on the total amount of the composition.

According to the fourth aspect of the present invention, in any one of the first to third aspects, the thermal expansion coefficient of the glass composition forming the dielectric layer (A) is 70 to 81 × 10 ⁻⁷ / A dielectric film characterized by a temperature of 0 ° C. is provided.

According to the fifth invention of the present invention, in the first invention, the glass composition forming the dielectric layer (B) is 15 to 40 mol% of SiO ₂ and B ₂ O _{3 in} terms of oxide. the 10-50 mol%, 20 to 50 mol% of ZnO, and the general _formula: (wherein, R, K, exhibits at least one alkali metal element selected from Na or Li.) _R 2 O is represented by A dielectric film containing 12 to 15 mol% of an alkali metal oxide is provided.

  Furthermore, according to the sixth invention of the present invention, in the first invention, the film thickness of the entire dielectric film is 10 to 60 μm, and the film thickness of the dielectric layer (A) is 5 to 50 μm. A dielectric film is provided.

On the other hand, according to the seventh aspect of the present invention relates to the sixth aspect of the present invention, on a glass substrate, in terms of oxide, the SiO _{2 1~15mol%, 10~50mol%} of B 2 _{O 3,} An alkali metal oxide represented by 30 to 50 mol% of ZnO and a general formula: R ₂ O (wherein R represents at least one alkali metal element selected from K, Na, or Li). After forming the lowermost dielectric layer (A) using a glass paste (a) composed of a glass composition having a glass transition point of 480 ° C. to 540 ° C. containing 0 to 12 mol%, a resin and a solvent, further thereon A dielectric paste (B) is formed by applying a glass paste (b) composed of a glass composition having a glass transition point of 480 ° C. to 540 ° C., a resin and a solvent, and baking to form a dielectric layer (B). A method is provided.

  According to the eighth invention of the present invention, in the seventh invention, after the glass paste (a) is applied on the glass substrate and baked to form the lowermost dielectric layer (A), Next, a dielectric paste (B) is formed by applying a glass paste (b) thereon and firing to provide a dielectric film manufacturing method.

The present invention is a dielectric film that does not contain harmful substances such as lead and bismuth and is composed of at least a lower dielectric layer in contact with a glass substrate and a second dielectric layer covering the lower dielectric layer. The dielectric layer is formed using a glass composition having a specific composition. Therefore, when a paste containing a glass composition is applied to a glass substrate for a display panel and baked at a predetermined temperature, the lowermost dielectric layer in contact with the glass substrate suppresses the warpage of the substrate, and the degree of warpage Can be made comparable to a glass composition containing lead or bismuth.
And since the second dielectric layer is formed of a glass paste containing components different from the glass composition forming the lowermost dielectric layer, both the substrate warpage and the electrical characteristics are satisfied. The dielectric film can be made.
For these reasons, the dielectric film of the present invention is useful as a dielectric film constituting a display panel such as PDP, VFD, FED, etc., and has an extremely great industrial value.

  Hereinafter, the dielectric film of the present invention and the manufacturing method thereof will be described in detail with reference to the drawings.

1. Dielectric Film The dielectric film of the present invention is a dielectric film having two or more dielectric layers capable of suppressing warpage of the glass substrate substantially without containing lead or bismuth, The lowermost dielectric layer (A) provided in 1 is ₁ to 15 mol% of SiO ₂ , 10 to 50 mol% of B ₂ O ₃ , ₃₀ to 50 mol% of ZnO, and general formula: R _{2 in} terms of oxide. Formed from a glass composition containing 0 to 12 mol% of an oxide of an alkali metal represented by O (wherein R represents at least one alkali metal element selected from K, Na or Li); The glass transition point is 480 ° C. to 540 ° C., while the glass transition point of the glass composition forming the dielectric layer (B) provided on the lowermost layer is 430 ° C. to 480 ° C. Features.

  That is, the dielectric film of the present invention (hereinafter also simply referred to as a dielectric) has a laminated structure as shown in FIG. 1 and is formed on a glass substrate with a glass composition containing no lead or bismuth. It consists of two or more layers, the lowermost dielectric layer (2) in contact with the substrate (4) and the dielectric layer (3) formed thereon, and the lowermost dielectric layer (2) is a glass substrate (4). ) And the dielectric layer (3) is formed thereon, thereby forming the dielectric film (1) having sufficient withstand voltage characteristics.

Up to now, a glass substrate for PDP or the like (hereinafter also simply referred to as a substrate) has used a single type of dielectric forming glass paste, which is applied to the substrate and baked to stack one or more dielectric layers. It had been. However, as described in the background art, when the dielectric is formed of one kind of glass composition substantially not containing lead or bismuth, the glass substrate is warped when the glass paste is fired. The present invention suppresses such warpage of the substrate by forming the dielectric laminated on the glass substrate into a dielectric film of two or more layers using at least two kinds of dielectric forming glass pastes. Intended.
Also, if the firing temperature of the display device is to be lowered, it is difficult to cope with the lowermost layer alone, so the lowermost layer is covered with a dielectric containing glass that is easier to soften, and the desired dielectric strength as a whole dielectric is covered. It is intended to obtain characteristics.

In the present invention, since the lowermost dielectric layer in contact with the glass substrate is a dielectric with a small warp, it can be softened at a lower temperature as a material for the dielectric layer formed thereon, and the substrate can be greatly warped. A glass composition may be used. This is because the lowermost dielectric layer absorbs the warp due to the firing of the laminated dielectric, so the warp of the substrate is not different from the warp that occurs when a dielectric is formed using a glass composition with a small warp. It is.
In other words, after covering the dielectric layer (hereinafter also referred to as the second layer) on the lowermost dielectric layer, when the second layer is fired, the lowermost dielectric immediately softens, This is because the shrinkage of the dielectric laminated thereon is not transmitted to the substrate. On the other hand, a glass substrate is much harder than a dielectric, and can only be warped by the shrinkage of the dielectric at the temperature at which the dielectric is fired.

As described above, when the lowermost dielectric is formed by the glass composition that hardly warps the substrate, even if the second dielectric that easily warps the substrate than the lowermost layer is formed thereon, The soda lime glass substrate is not warped.
However, after forming the lowermost dielectric layer with the glass composition for the second dielectric layer so that the positional relationship of the layers is reversed, the second dielectric layer is made into the glass composition for the lowermost layer. When formed by an object, the warpage of the substrate is not improved at all, and the value of the warpage is a value reflecting the lowermost dielectric material. In other words, the warpage of the substrate is determined by the composition of the glass composition that directly touches the substrate and is not controlled by the glass composition that does not touch the substrate.

In forming a dielectric film on a glass substrate of PDP or VFD, there have been cases where a dielectric is formed by laminating a plurality of dielectric pastes. This is to compensate for defects such as pinholes by forming a dielectric layer again on the dielectric formed on the substrate and found to have defects.
For example, missing or defective pinholes or voids may occur in the dielectric film formed on the front plate of a PDP device, and if the device is manufactured as it is, it will cause electrode disconnection in the lighting inspection upon completion, Even if the product yield may decrease, or even if it does not become defective in the lighting inspection, the cause of the failure over time is inherent, so the product becomes low in reliability.
In view of this, Japanese Patent Laid-Open No. 2000-294141 adds a process of inspecting a dielectric film after printing and baking and before forming an MgO film, and correcting a detected defect / defect. Apply the correction glass paste to the open gaps / defects, and after drying, modify the shape as necessary. For open defects, the defects that are opened by laser irradiation In the same manner, a correction glass paste is applied, and after drying, the shape is corrected as necessary. In this case, a material having substantially the same composition as that of the dielectric layer is usually used for the correction glass paste.

  The present invention does not use a material having the same glass composition as in the case of correcting a defect generated in such a dielectric layer, but a glass composition in which the substrate is difficult to warp and a glass composition having a different component from that of the glass composition. By forming two or more dielectric layers using, it is intended not only to suppress the warpage of the substrate but also to satisfy the withstand voltage characteristics.

The thickness of the dielectric film is not particularly limited, but it is preferable that the entire film thickness is 10 to 60 μm and the film thickness of the lowermost layer is 5 to 50 μm. If the total film thickness is less than 10 μm, it is not preferable in terms of voltage resistance, and if the lowermost layer is less than 5 μm, the substrate may be warped, which is not preferable. It is more preferable that the thicknesses of the dielectrics of the first layer and the second layer be 10 μm or more, since problems of withstand voltage characteristics of the substrate and the entire dielectric do not occur. However, it is not preferable in terms of cost if the total film thickness exceeds 60 μm or the film thickness of the lowermost layer exceeds 50 μm.
In the present invention, since the second dielectric layer has a glass transition point lower than that of the lowermost dielectric layer, when the lowermost dielectric layer and the second dielectric layer are fired simultaneously, the second dielectric layer is It may soften first and inhibit the debinding of the lowermost dielectric. In order to prevent such a situation, the thickness of each dielectric (after firing) is desirably 50 μm or less.

  Note that the dielectric film is not limited to two layers, and two or more layers can be provided as long as the object of the present invention is not impaired. The dielectric material is made of the same material as the second layer on the second dielectric layer. The body can be formed.

2. Glass Composition In the present invention, the lowermost dielectric layer (A) in contact with the glass substrate and the second dielectric layer (B) are formed of glass compositions having different glass components.

In the present invention, the glass composition for forming a dielectric layer of the lowermost, in terms of oxide, the _{SiO 2 1~15mol%, B 2 O} 3 and 10-50 mol%, 30 to 50 mol% of ZnO, And an oxide of an alkali metal: R ₂ O (wherein R represents at least one alkali metal element selected from K, Na or Li) and a glass transition point of 480 ° C. to The glass composition for forming the second dielectric layer at 540 ° C. has a glass transition point of 430 ° C. to 480 ° C.

(A) Bottom dielectric layer When a glass paste composition containing a glass composition (hereinafter also simply referred to as a glass paste) is applied to a glass substrate and baked to form a dielectric, it affects the warpage of the substrate. Is the bottom dielectric layer. This is because the glass shrinks during the baking process of the glass paste, causing the substrate to warp.

  In the present invention, the lowermost dielectric layer must be formed using a glass composition having a glass transition point of 480-540 ° C. A preferable glass transition point is in the range of 480 to 510 ° C. The glass transition point can be measured by TG-DTA or TMA.

Since a display device bonds two glass substrates together and seals them to form a vacuum vessel, the glass transition point of the glass composition has a close relationship with the heating conditions of the sealing process of the display device. Yes. Since the sealing step is performed by softening and firing the sealing material at 430 ° C., the glass transition point of the glass composition forming the dielectric film of the present invention is set higher than this temperature, and the partition walls already formed And the dielectric must not be softened.
In general, a stable glass can be obtained if the desired softening point is set, but the glass transition point of the glass composition is within this range because the substrate is warped due to the blending with SiO ₂ or an alkali metal oxide. It is important that the composition be within the range.
As described above, the baking temperature of the display device is 600 ° C. at the maximum, but preferably 570 ° C. or less. Since the warpage of the substrate is the most important issue even under such a firing temperature constraint, the glass composition contained in the lowermost dielectric is configured as follows.

SiO ₂ in the glass is an essential component and a component that becomes a glass network former. The content in the glass is 1 to 15 mol% in terms of oxide. If the content is less than 1 mol%, the water resistance and chemical resistance of the glass are inferior, and if it exceeds 15 mol%, a desired softening point is obtained. The alkali metal oxide R ₂ O component to be increased increases and warps the substrate after firing. A preferable content is 3 to 13 mol%.

B ₂ O ₃ in the glass is an essential component, and is a component that lowers the softening point and increases fluidity to stabilize the glass. The content in the glass is 10 to 50 mol% in terms of oxide, and if the content is less than 10 mol%, the softening point becomes high and a desired value cannot be realized, and if it exceeds 50 mol%, the softening point becomes low and the desired value is obtained. The value cannot be realized and the water resistance and chemical resistance of the glass are inferior. A more preferable content is 45 mol% or less.

  ZnO in the glass is an essential component and is a component that lowers the softening point and appropriately adjusts the thermal expansion coefficient. Content in glass is 30-50 mol% in conversion of an oxide. If the content in the glass is less than 30 mol%, the desired softening point cannot be realized, and if it exceeds 50 mol%, vitrification becomes difficult. A more preferable content is 30 to 45 mol%.

This is because if a desired glass is obtained by obtaining a desired softening point, the substrate warps due to the blending with SiO ₂ or an alkali metal oxide.
Alkali metal oxides _{R 2} O is an essential component of the _glass, K 2 O, contains _Na 2 O, or any one or more of Li ₂ O. These are components that lower the softening point and increase the thermal expansion coefficient.
The R ₂ O content in the glass is 0 to 12 mol% in terms of oxide. If this content exceeds 12 mol%, the substrate after firing is greatly warped.

In general, if the thermal expansion of the glass composition is larger than that of the glass substrate, the substrate is warped when the glass composition is applied to the substrate and baked. This is because the glass composition on the substrate contracts as the temperature decreases in the process from the heating during the baking to the temperature falling. That is, since the glass composition tends to shrink by the amount of thermal expansion coefficient, naturally the substrate also shrinks. However, if the shrinkage of the glass composition is larger than the shrinkage of the substrate (that of the glass composition is larger than the thermal expansion coefficient of the substrate). If so, the glass composition side of the substrate will shrink more than the side without the glass composition.
In other words, the substrate warps due to the difference in the degree of shrinkage depending on the surface of the substrate. On the contrary, if the shrinkage of the substrate is larger than the shrinkage of the glass composition, the glass composition is compressed by the substrate and the substrate is not warped.

However, even if the thermal expansion of the glass composition is smaller than that of the substrate, the substrate may be warped.
The present applicant has confirmed that the composition of glass such as R ₂ O has a great influence on the warpage of the substrate and is also caused by the balance of the composition with SiO ₂ and ZnO. Among the glasses having a glass transition point of 500 ° C. and containing no lead, glass containing R ₂ O exceeding 12 mol% and glass containing less than 12 mol% R ₂ O, When the warpage was examined, the former (glass containing a lot of R ₂ O) was more warped. This is because glass containing a large amount of R ₂ O aggregates at a temperature near the softening point, and sinters into a glass film, forcibly shrinks, whereas glass with less R ₂ O has a softening point or higher. This is probably because the glass obtains fluidity at a temperature of 5 and melts with the adjacent glass particles to form a glass film, so that excessive shrinkage does not occur.

Compared with glass containing lead having the same softening point, the glass not containing lead has a feature that it contains a large amount of R ₂ O to obtain a desired softening point. This is why the substrate may be warped when glass containing lead is used, although glass containing lead does not warp after firing.
R ₂ O conducts as R ⁺ ions in the glass and adversely affects electrical insulation. Also from this viewpoint, the content of R ₂ O is limited to 12 mol% or less.

In addition, BaO, which is an alkaline earth metal oxide, has an effect of lowering the softening point of glass, and can be added up to 35 mol%. BaO has the effect of increasing the coefficient of thermal expansion, and the addition amount described above is desirable from this viewpoint. The content in glass is preferably 10 to 20 mol% in terms of oxide.
CaO and SrO can be appropriately added to the glass composition of the present invention. CaO and SrO are not essential components for glass, but the inclusion of these has the effect of stabilizing the glass. However, these have the effect of increasing the thermal expansion coefficient, and if they are contained excessively, the thermal expansion coefficient increases, making them unsuitable for using soda lime glass or the like as a substrate. The content of CaO and SrO in the glass is desirably 35 mol% or less in terms of oxide. In particular, the content of CaO is preferably 1 to 5 mol% in terms of oxide.

Further, the glass composition of the present invention can be added to ZrO ₂ as appropriate. ZrO ₂ is not an essential component of glass, but has an effect of improving water resistance and chemical resistance. However, if the content in the glass exceeds 15 mol% in terms of oxide, the softening point of the glass is raised and a desired value cannot be realized.
Al ₂ O ₃ is not an essential component of glass, but has an effect of improving water resistance and chemical resistance. However, if the content in the glass exceeds 15 mol% in terms of oxide, the softening point becomes high and a desired value cannot be realized.

Powder particle size of the glass composition, it is desirably 10μm or less at D _50, more preferably not more than 5 [mu] m. When the particle size is larger than 10 μm, a dense dielectric cannot be obtained. The particle size of the powder of the glass composition can be confirmed with Microtrac (registered trademark). In order to obtain a powder having a desired particle size, it can be pulverized by a known means such as a ball mill or a jet mill.

  In order to prepare the glass composition, a single glass composition may be used, or a plurality of glass compositions may be prepared and mixed. Even in a glass composition that is not practical for causing the warpage of the substrate, the warpage of the substrate can be improved by mixing each component so as to become the glass composition defined in the present invention.

In order to form a dielectric such as PDP, an inorganic oxide can be mixed with the glass composition. Examples of the inorganic oxide include alumina, silica, forsterite, zirconia, zircon, titania, and heat-resistant inorganic pigment, and one or more inorganic oxides selected from these can be added to the glass composition. Transparency may be impaired by adding an inorganic oxide, but in the case of a PDP transparent dielectric, an inorganic oxide can be added within a range that can ensure the transmittance of the glass film, thereby making the mechanical properties of the glass film The strength can be improved.
As heat-resistant inorganic pigments, Fe-Co-Cr composite oxide, Cu-Cr-Mn composite oxide, Cu-Cr-Fe composite oxide, Ni-Mn-Fe-Co composite oxide, Fe-Mn composite oxide Products, black pigments of Fe—Cu—Mn-based composite oxides, green pigments of Cr oxides, and the like can be used.
The particle size _{D 50} of the inorganic oxide, 10 [mu] m or less, more preferably equal to or less than 5 [mu] m. If it is larger than this, a dense dielectric cannot be obtained.

The thermal expansion coefficient of the glass ceramic material is determined by the glass composition and the inorganic oxide, and can be controlled by changing these combinations. The coefficient of thermal expansion is desirably in the range of 50 to 87 × 10 ⁻⁷ / ° C. The thermal expansion coefficient of a substrate such as soda lime glass is 83 to 87 × 10 ⁻⁷ / ° C., and if it is not less than this value, the device warps during firing.
The thermal expansion coefficient of silica is 140 × 10 ⁻⁷ / ° C., and that of forsterite is 95 × 10 ⁻⁷ / ° C., and the effect of increasing the thermal expansion coefficient can be obtained by blending these into the glass composition. Silica (quartz) is known to undergo phase transition, and the thermal expansion coefficient changes abruptly when phase transition occurs to cristobalite or the like. Cracks may occur in the partition walls and the dielectric due to changes in the thermal expansion coefficient. Quartz glass can be used to prevent such a situation. Quartz glass has a thermal expansion coefficient of 55 × 10 ⁻⁷ / ° C., and the effect of lowering the thermal expansion coefficient can be obtained by blending it with the glass composition.

Although only one type of inorganic oxide powder may be selected, it is not limited thereto, and a plurality of types can be combined. TiO ₂ can be added to make the barrier ribs and dielectric white. Moreover, the addition of TiO ₂ is also effective when it is desired to increase the dielectric constant.
The content of the inorganic oxide powder varies depending on the application, but is desirably less than that of glass, and is 5 to 20% by weight, preferably 8 to 15% by weight. In the case of PDP, if the content is less than 5% by weight, a dense dielectric film can be formed, but a white dielectric cannot be realized. Moreover, when it exceeds 20 weight%, there exists a problem that it becomes impossible to implement | achieve a precise | minute dielectric material.

(B) Second dielectric layer In the present invention, the glass composition for forming the second dielectric layer must have a glass transition point of 430 ° C to 480 ° C. Further, _SiO 2 _15~40mol% in terms of _{oxide, B 2 O 3 10~50mol%,} ZnO 20~50mol%, total _{R 2 O (K} 2 _O of an alkali metal oxide, Na 2 O, _Li 2 O ) It is desirable to contain 12-15 mol%.

  Originally, it would be efficient if the entire layer could be formed with only the dielectric corresponding to the lowermost layer that would not easily warp the substrate. However, electrical characteristics such as withstand voltage may not be satisfied. Since the lowermost dielectric using a glass composition that hardly causes warpage of the substrate is subject to compositional restrictions as described above, the electrical characteristics are sacrificed. For this reason, the second dielectric layer needs to have an optimal composition so as to compensate for the electrical characteristics of the sacrificial lowermost dielectric layer and obtain desired electrical characteristics as a whole.

  Here, the electrical characteristics of the dielectric film are affected by whether or not the glass constituting the dielectric film is firmly fixed. If the glass is softened and the glass and filler particles are firmly fixed, high withstand voltage characteristics can be ensured without mechanically breaking even when an electrical impact is applied. For this purpose, it is necessary that the glass particles are sufficiently softened.

Moreover, in the manufacturing process of a display device, the firing temperature is required to be lowered in order to ensure energy saving and dimensional accuracy. However, as described above, the amount of SiO ₂ , ZnO, R ₂ O, or the like is defined in the glass contained in the lowermost dielectric layer. Therefore, even if increasing the component for enhancing the fluidity of such stable glass B ₂ O ₃ and an alkaline earth oxide, it is difficult to lower than its glass transition point 480 ° C.. The glass contained in the lowermost dielectric may be insufficient for lowering the firing temperature due to its compositional restrictions. Therefore, the second dielectric layer must be formed using a glass composition having a glass transition point of 430 to 480 ° C.

Accordingly, the glass contained in the second dielectric layer is preferably defined as follows.
The content of SiO _{2 in} the glass is not particularly limited, but is preferably 15 to 40 mol% in terms of oxide. If the content is less than 15 mol%, the water resistance and chemical resistance of the glass are inferior, and if it exceeds 40 mol%, a desired softening point is obtained, so that the alkali metal oxide R ₂ O component described later increases and warps the substrate after firing. Produce. A preferable content is 18 to 35 mol%.

The content of B ₂ O ₃ in the glass is not particularly limited, but is 10 to 50 mol% in terms of oxide, and if the content is less than 10 mol%, the softening point becomes high and a desired value can be realized. However, if it exceeds 50 mol%, the softening point becomes low and the desired value cannot be realized, and the water resistance and chemical resistance of the glass are inferior. A more preferable content is 45 mol% or less.

  The content of ZnO in the glass is not particularly limited, but is 20 to 50 mol% in terms of oxide. If the content in the glass is less than 20 mol%, the desired softening point cannot be realized, and if it exceeds 50 mol%, vitrification becomes difficult. A more preferable content is 25 to 45 mol%.

The content of the alkali metal oxide R ₂ O (one or more of K ₂ O, Na ₂ O, or Li ₂ O) is not particularly limited, but is 12 to 15 mol% in terms of oxide. is there. Since this content is 12 mol% or more, since it is easy to obtain, it is preferable. However, if the content exceeds 15 mol%, the electrical characteristics are deteriorated, which is not preferable. That is, as described above, R ₂ O conducts as R ⁺ ions in the glass and adversely affects the electrical insulation.

Further, BaO which is an alkaline earth metal oxide is not particularly limited, but has an effect of lowering the softening point of the glass, and can be added up to 35 mol%. BaO has the effect of increasing the thermal expansion coefficient. The content in glass is preferably 10 to 20 mol% in terms of oxide.
In the present invention, CaO and SrO can be appropriately added to the glass composition forming the second dielectric layer. Inclusion of these has the effect of stabilizing the glass. However, these have the effect of increasing the thermal expansion coefficient, and if they are contained excessively, the thermal expansion coefficient becomes large and is inappropriate for using soda lime glass or the like as a substrate. The content of CaO and SrO in the glass is desirably 35 mol% or less in terms of oxide. In particular, the content of CaO is preferably 1 to 5 mol% in terms of oxide.

Further, the glass composition can be added to ZrO ₂ as appropriate. ZrO ₂ has an effect of improving water resistance and chemical resistance. However, if the content in the glass exceeds 15 mol% in terms of oxide, the softening point of the glass is raised and a desired value cannot be realized.
Al ₂ O ₃ is not an essential component of glass, but has an effect of improving water resistance and chemical resistance. However, if the content in the glass exceeds 15 mol% in terms of oxide, the softening point becomes high and a desired value cannot be realized.

Powder particle size of the glass composition, like the bottom layer, it is desirably 10μm or less at D _50, more preferably not more than 5 [mu] m. When the particle size is larger than 10 μm, a dense dielectric cannot be obtained.

The reason why the dielectric layer is formed by using the glass composition of the material different from the lowermost layer and the second layer in this way is that the substrate is warped in the conventional glass composition, so that the lowermost layer is formed. However, it is necessary to suppress the warpage of the substrate using the glass composition defined in the present invention. However, if all the dielectric films are formed using only this glass composition, the withstand voltage characteristic becomes insufficient. is there.
However, the second dielectric layer is not required to have a function of suppressing the warp of the glass substrate and is not strictly restricted in terms of composition, so that the degree of freedom in material design is expanded. That is, the second dielectric layer may have a composition not defined above as long as the object of the present invention is not impaired. For example, the glass composition used for the second dielectric layer can be made to have desired characteristics by increasing SiO ₂ or R ₂ O. However, the glass transition point is limited to 430 ° C. to 540 ° C. as long as soda lime glass is used for the substrate even if the compositional freedom of the second layer glass composition is widened.

4). Glass Paste Composition In the present invention, the glass paste composition comprises the above glass composition, resin, and solvent as essential components, and an inorganic oxide powder, a dispersant and the like are appropriately added as necessary.

The resin is a component that maintains the viscosity of the paste, maintains the shape after coating and drying, and improves the chemical resistance of the dried film. The resin must decompose or burn in the firing process and be completely removed below the softening point of the glass composition. This is because a resin that burns at a temperature higher than the softening point traps the generated degassing in the softened glass film and generates many voids such as bubbles.
From this point of view, preferred resins include ethyl cellulose, acrylic, polyvinyl butyral, and methylstyrene. Acrylic includes methacrylic resin. These resins may be used alone or a plurality of types may be mixed.
The amount of the resin in the glass paste composition is usually 0.5 to 10% by weight with respect to 100% by weight of the inorganic component. Here, the inorganic component is composed of a glass composition and an inorganic oxide (ceramic) added as necessary. When the amount of the resin is less than 0.5% by weight, the glass ceramic composition powder in the paste is settled, which impairs the storage stability of the paste. On the other hand, if the amount of the resin is more than 10% by weight, the viscosity becomes high and a viscosity suitable for coating cannot be obtained unless a large amount of solvent is added.

The solvent is an essential component for improving the flowability of the paste. Moreover, not only can the resin be dissolved, but it must be volatilized in the drying process. If only the volatility is emphasized and a solvent having a boiling point of less than 150 ° C. is used, the paste dries in the coating process, resulting in poor workability.
From this point of view, the boiling point of the solvent is desirably 150 ° C. or higher. From the solubility of the resin, terpinol, dihydroterpinol, butyl carbitol acetate, butyl carbitol, 2,2,4-trimethyl-1,3-pentane Diol monobutyrate or the like is selected.
The amount of the solvent is 20 to 45% by weight with respect to 100% by weight of the inorganic component, although it depends on the type of the solvent. When the blending amount is less than 20% by weight, it is difficult to form a paste. When the blending amount exceeds 45% by weight, the shrinkage of the film during drying increases and cracks tend to occur in the dried film. In addition, when the solvent is large, not only energy consumption during drying is increased, but also shrinkage during drying is increased, and cracks may occur in the dried film due to uneven drying temperature.

  Additives known as thick film glass pastes such as antifoaming agents, dispersing agents, and plasticizers can be added to the glass paste composition. In order to produce such a glass paste composition, no special means is required, and a known method such as a roll mill or a ball mill can be used.

The glass paste composition differs only in the glass composition depending on whether the dielectric layer to be formed is the lowermost layer or the second layer, and the other components are substantially the same.
That is, the second dielectric layer-forming glass composition is a material capable of lowering the glass transition point than the lowermost dielectric layer, even if the lowermost dielectric layer causes warping of the substrate. If it can be adopted. The second dielectric layer forming glass composition laminated on the lowermost layer does not participate in the warp of the substrate.
The glass paste composition is printed on a soda lime glass substrate by a method such as screen printing, the solvent is removed by drying, and is baked to form a dielectric film.

5. Method for producing a dielectric film manufacturing method of the present invention the dielectric film, on a glass substrate, in terms of oxide, the _{SiO 2 1~15mol%, B 2 O} 3 and 10-50 mol%, 30 to 50 mol of ZnO % And a general formula: R ₂ O (wherein R represents at least one alkali metal element selected from K, Na, or Li) 0 to 12 mol% of an oxide of an alkali metal After forming the lowermost dielectric layer (A) using a glass paste (a) composed of a glass composition having a glass transition point of 480 ° C. to 540 ° C., a resin and a solvent, the glass transition point is 480 on the dielectric layer (A). A glass paste (b) composed of a glass composition, a resin and a solvent at a temperature of 540 ° C. to 540 ° C. is applied and baked to form a dielectric layer (B).

In order to manufacture the dielectric film by the method of the present invention, from the viewpoint of suppressing the warpage of the glass substrate, first, the lowermost dielectric is formed with a glass paste (also referred to as a thick film paste) that is less likely to warp the substrate. Then, a dielectric film composed of at least two dielectric layers is formed thereon by forming a dielectric having a composition specific to electrical characteristics in order to realize a withstand voltage characteristic.
For example, the lowermost dielectric glass paste (a) is formed on a glass substrate by printing and firing, and then the second dielectric glass paste (b) is printed and fired. Alternatively, the first dielectric glass paste (a) is printed and dried, and then the second and subsequent dielectric glass pastes (b) are sequentially printed, dried and laminated, and then fired at once. By forming.

In the process of firing the dielectric, even if the lowermost dielectric and the second-layer dielectric are fired separately or simultaneously, the same effects can be obtained on the warpage and electrical characteristics of the substrate.
The warpage of the substrate depends on the dielectric of the lowermost layer, and even if the dielectric of the lowermost layer is not fired and completed, the dielectric of the lowermost layer affects the second layer and the dielectric on the second layer and the substrate. There is no difference from the case where the lowermost dielectric is fired in advance. This is because if the lowermost dielectric is not fired, the lowermost dielectric is not fixed to the substrate, so that the warpage of the second dielectric that is fired at the same time is not transmitted to the substrate.
Thus, if the dielectric material of a several layer is formed with a different glass paste composition, the characteristic of both the curvature of a board | substrate and an electrical property can be satisfied.

As described above, since soda lime glass is frequently used as a glass substrate in PDP, VFD, and FED, it is necessary to fire the glass paste composition applied on the glass substrate at a temperature of 600 ° C. or lower.
In addition, the formation of the dielectric is not limited to printing of a thick film glass paste, for example, a green sheet material obtained by applying and drying a dielectric glass paste may be pasted. it can.

  The display device forms a vacuum container by bonding and sealing two glass substrates or the like. The sealing process is performed by heating up to about 430 ° C. and softening and baking the sealing material. Since the glass transition point of the glass composition used in the present invention is higher than this temperature, the barrier ribs and dielectrics already formed are used. The dimensional accuracy of the display device can be ensured without softening.

  Examples of the present invention and comparative examples are shown below, but the present invention is not limited to these examples.

(Evaluation of substrate warpage)
The warpage of the substrate was evaluated by the following method after applying the glass paste to the glass substrate and firing it. In order to make it easy to detect the warping of the substrate after baking, a soda-lime glass substrate with a 50 mm x 50 mm square and a thickness of 0.55 mm is used, and a glass paste is screen-printed on one side and dried at 120 ° C for 5 minutes. Then, baking was performed in a belt-type baking furnace at a peak condition of 580 ° C. × 5 minutes, and a glass film having a baking film thickness of 20 μm was baked to obtain an evaluation substrate.
The surface of the substrate on which the glass paste was not baked was traced by 40 mm with a surface roughness meter (manufactured by Tokyo Seimitsu, surfcom E-MD-S39A type), and the warpage of the glass substrate was confirmed. The thermal expansion coefficient of the substrate is 86 × 10 ⁻⁷ / ° C.
The warping of the substrate is “positive warping” when the side where the glass paste is applied is warped concavely, and the opposite (“warping negatively” when it is convex toward the side where the paste is applied). It was. The obtained results are shown as absolute values. If the warpage of the substrate is in the range of 0 to 50 μm, there is no practical problem.

(Evaluation of withstand voltage)
A silver paste was baked on a glass substrate to form a silver electrode, and the glass paste was printed and fired with the combinations shown in Table 2 to form a laminated dielectric. A silver paste was printed on the dielectric and fired (peak temperature 500 ° C. × 5 minutes) to obtain a silver electrode. When viewed from the cross section, the dielectric (width: 3 mm × 3 mm) is sandwiched between silver electrodes. A direct current potential was applied between the silver electrodes of this sample, and the potential at which dielectric breakdown occurred was recorded.

(Example 1-5)
The glass used was one having a composition shown in Table 1 (glass A-F) so as to contain 0 to 12 mol% of an alkali metal oxide without containing Pb and Bi. This glass composition was melted at 1300 ° C., rapidly cooled, and pulverized with a ball mill. The particle size of the obtained glass powder was measured with Microtrac (registered trademark), and the glass transition point and softening point were measured with TG-DTA (Seiko Denshi TG / DTA320 type). Table 1 shows the particle size of the obtained glass powder. In addition, content of each component in Table 1 is oxide conversion mol%.
The glass powder was pressure-formed into a rod shape and fired at 570 ° C. for 30 minutes to obtain a sample having a diameter of 4 mm and a length of 10 mm. This sample was set in TMA (TMA320 type manufactured by Seiko Denshi Co., Ltd.), and the thermal expansion coefficient was measured.
40% by weight of vehicle was added to 100% by weight of a mixture of 10% by weight of Cu—Cr—Mn composite oxide powder with respect to 90% by weight of glass powder, and mixed by a roll mill to obtain a glass paste composition. The vehicle was obtained by mixing 10% by weight of ethyl cellulose (molecular weight 80000) in the resin and 90% by weight of terpinol in the solvent and heating to 60 ° C. to obtain a vehicle. Next, using this glass paste composition, the warpage of the substrate was evaluated by the above method.
Furthermore, a glass paste was printed on the glass film for the substrate and baked in a belt-type baking furnace at 560 ° C. for 5 minutes to obtain a glass film having a total thickness of 40 μm. The back surface of the substrate was traced with a surface roughness meter to confirm the warpage of the substrate. In addition, the withstand voltage characteristics were evaluated as described above. Table 2 shows the types of glass used in the first and second layers, the warpage of the substrate, the withstand voltage characteristics, and the like.

(Comparative Example 1-4)
As glass for forming the dielectric of the first layer, an alkali metal oxide content exceeding 12 mol% or containing Pb (Comparative Examples 1, 3, 4) is the same as the example. Thus, glass compositions shown in Table 1 were prepared. The glass transition point, softening point, thermal expansion coefficient, and particle size were measured. Next, the substrate warpage and withstand voltage characteristics were evaluated in the same manner as in the examples. In Comparative Example 2, both the first layer and the second layer were laminated using only glass A with little warpage to form a dielectric film. Table 2 shows the types of glass used in the first and second layers, the warpage of the substrate, the withstand voltage characteristics, and the like.

"Evaluation"
The thermal expansion coefficients of the glass compositions prepared in the above examples and comparative examples are all smaller than that of the substrate. However, when the glass compositions of Comparative Examples 1 and 3 are used for forming the lowermost layer, the warpage of the substrate is too large and exceeds the practical level. It can be seen that the dielectric (Comparative Example 2) in which only the glass A with little warpage is laminated has a lower withstand voltage than the dielectric (Comparative Example 1) in which the glass A is laminated on the glass E.
On the other hand, in the glass composition of Example 1-4, the warpage of the substrate is within a practical level, which is similar to the conventional lead-containing glass shown as Comparative Example 4. Thereby, it turns out that the glass composition of this invention is useful as a dielectric material formed in the glass substrate for display devices, such as PDP.

It is sectional drawing which shows the laminated structure of the dielectric film of this invention. It is a partially broken perspective view which shows the front board and back board of the structure of a general AC type PDP. It is a partially broken perspective view which shows the structure of VFD. It is sectional drawing which shows the structure of FED.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Dielectric film 2 1st dielectric layer 3 2nd dielectric layer 4 Glass substrate 10a Front board 10b Back board 11 Transparent electrode 12 Bus electrode 13 Address electrode 14 MgO electrode 15 Dielectric film 16 Partition 17 Phosphor 21 Face Glass 22 Glass electrode 23 Grid electrode 24 Segment electrode 25 Insulating layer 26 Filament 27 Wiring 28 Terminal 31a, 31b Glass substrate 32 Anode 33 Phosphor 34 Gate electrode 35 Spacer 36 Emitter electrode 37 Resistance layer 38 Cathode electrode B Blue G Green R Red

Claims (8)

A dielectric film having two or more dielectric layers capable of suppressing warpage of the glass substrate substantially without containing lead or bismuth,
Lowermost dielectric layer provided on a glass substrate (A) is in terms of oxide, the _{SiO 2 1~15mol%, B 2 O} 3 and 10-50 mol%, 30 to 50 mol% of ZnO, and the general formula : Formed from a glass composition containing 0 to 12 mol% of an oxide of an alkali metal represented by R ₂ O (wherein R represents at least one alkali metal element selected from K, Na or Li). The glass transition point is 480 ° C. to 540 ° C., while the glass transition point of the glass composition forming the dielectric layer (B) provided on the lowermost layer is 430 ° C. to 480 ° C. A dielectric film characterized by being.   The glass composition forming the dielectric layer (A) further contains 1 to 35 mol% of an alkaline earth metal oxide selected from BaO, CaO or Sr0 in terms of oxide. The dielectric film according to claim 1.   The glass composition forming the dielectric layer (A) further comprises at least one inorganic oxide powder selected from alumina, silica, forsterite, zirconia, zircon, titania or heat-resistant inorganic pigment with respect to the total amount of the composition. The dielectric film according to claim 1, further comprising 5 to 20% by weight. The dielectric film according to claim 1, wherein a thermal expansion coefficient of the glass composition forming the dielectric layer (A) is 70 to 81 × 10 ⁻⁷ / ° C. Glass composition forming dielectric layer (B) is in terms of oxide, the _{SiO 2 15~40mol%, B 2 O} 3 and 10-50 mol%, 20 to 50 mol% of ZnO, and the general formula: _{R 2} The alkali metal oxide represented by O (wherein R represents at least one alkali metal element selected from K, Na, or Li) is contained in an amount of 12 to 15 mol%. The dielectric film described in 1.   2. The dielectric film according to claim 1, wherein the entire dielectric film has a thickness of 10 to 60 μm, and the dielectric layer (A) has a thickness of 5 to 50 μm. On a glass substrate, in terms of oxide, the _{SiO 2 1~15mol%, B 2 O} 3 and 10-50 mol%, 30 to 50 mol% of ZnO, and the general _{formula: R} 2 O (wherein, R, K , A glass composition having a glass transition point of 480 ° C. to 540 ° C., a resin and a solvent containing 0 to 12 mol% of an oxide of an alkali metal represented by Na or Li. After forming the lowermost dielectric layer (A) using the glass paste (a) comprising, a glass paste comprising a glass composition having a glass transition point of 480 ° C. to 540 ° C., a resin and a solvent ( The method for producing a dielectric film according to claim 1, wherein b) is applied and fired to form the dielectric layer (B).   A glass paste (a) is applied onto a glass substrate and baked to form a lowermost dielectric layer (A). Next, a glass paste (b) is applied thereon and baked to form a dielectric. 8. The method of manufacturing a dielectric film according to claim 7, wherein the body layer (B) is formed.

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