JP5083704B2 - Bismuth sealing material - Google Patents

Description

  The present invention relates to sealing a flat display device such as a plasma display panel (hereinafter referred to as PDP), a field emission display (hereinafter referred to as FED), a fluorescent display tube (hereinafter referred to as VFD), a crystal resonator, and an IC. The present invention relates to a bismuth-based sealing material suitable for sealing electronic parts such as packages.

  Conventionally, glass has been used as a sealing material for flat display devices and the like. Glass is excellent in chemical durability and heat resistance as compared with a resin-based adhesive, and is suitable for ensuring airtightness of a flat display device or the like.

  These glasses require various properties such as mechanical strength, fluidity, and electrical insulation depending on the application, but they can be used at least at temperatures that do not degrade the fluorescence properties of phosphors used in flat panel displays, etc. It is required to be. Therefore, as a glass that satisfies the above characteristics, lead borate glass (see, for example, Patent Document 1) containing a large amount of PbO that has an extremely large effect of lowering the melting point of the glass has been widely used.

However, recently, environmental problems have been pointed out with respect to PbO contained in lead borate glass, and it is desired to replace lead borate glass with glass containing no PbO. Therefore, various low melting glass has been developed as a substitute for lead borate glass. Among them, the bismuth glass (also referred to as Bi ₂ O ₃ —B ₂ O ₃ glass) described in Patent Document 2 is a lead borate glass in various properties such as chemical durability and mechanical strength. Therefore, it is expected as an alternative candidate.

By the way, the sealing material used for PDP goes through the following processes. First, using a kneading apparatus such as a three-roll mill, the sealing material and the vehicle are uniformly dispersed to form a paste. In general, a vehicle contains an organic solvent, a resin, and the like, and a nitrocellulose, an acrylic resin, or the like that is thermally decomposed well at a temperature below the softening point of glass is used as the resin. Next, a paste prepared on the outer peripheral edge of the back substrate of the PDP is applied, and the vehicle components are pyrolyzed or incinerated at a high temperature to perform primary firing (glaze firing, temporary firing). The primary firing is performed under temperature conditions where the resin used in the vehicle is completely pyrolyzed. Further, secondary firing (main firing) of the sealing material is performed to seal the front substrate and the rear substrate of the PDP. Finally, the inside of the PDP is evacuated through the exhaust pipe, and then a necessary amount of rare gas is injected to seal the exhaust pipe. In this way, the PDP is manufactured.
Japanese Unexamined Patent Publication No. Sho 63-315536 JP-A-6-24797

  In recent years, the primary firing of the sealing material and the primary firing of the phosphor material are sometimes performed simultaneously for the purpose of improving the production efficiency of the PDP.

  The phosphor material is used for use after the phosphor powder is uniformly dispersed in a vehicle made of an organic solvent or resin and processed into a paste. Generally, as a resin used for this vehicle, ethyl cellulose having good viscosity characteristics and the like are used. Note that ethyl cellulose has a higher decomposition temperature and inferior thermal decomposability than nitrocellulose and acrylic resins.

  The primary firing of the phosphor material is performed under the condition that the thermal decomposition of ethyl cellulose is completed in a short time, and specifically, is performed at about 500 ° C. Therefore, since the decomposition temperature of ethyl cellulose is higher than the decomposition temperature of nitrocellulose, when the primary firing of the sealing material and the primary firing of the phosphor material are performed simultaneously, the firing temperature is about 500 ° C.

  In addition, as a resin used for the vehicle in which the phosphor material is dispersed, a method using a resin having good thermal decomposability may be considered, but such a resin is not sufficiently viscous and the workability of applying the phosphor material is deteriorated. Therefore, conversely, there is a possibility that the manufacturing efficiency of the PDP is lowered.

  Further, the secondary firing provided after the primary firing of the sealing material is performed at a temperature that does not deteriorate the fluorescent characteristics of the phosphor, and is performed at as low a temperature as possible in consideration of energy efficiency and the like. Specifically, the secondary firing of the sealing material is performed at a temperature of about 450 to 500 ° C.

  By the way, Patent Document 2 describes a bismuth-based sealing material that can be used for sealing electronic parts. However, this bismuth-based sealing material has poor devitrification resistance as compared with lead borate-based glass. In particular, when a refractory filler powder is contained, the devitrification property is remarkable. Accordingly, when the bismuth-based sealing material described in Patent Document 2 is used, the bismuth-based glass is devitrified when the sealing material and the phosphor material are subjected to primary firing at the same time, that is, when firing at about 500 ° C. In the subsequent secondary firing, the sealing material becomes difficult to flow, and as a result, it becomes impossible to ensure the airtight reliability of the PDP.

  In view of the above circumstances, the present invention provides a bismuth-based sealing material that does not devitrify even when subjected to primary firing at 500 ° C. and flows well during secondary firing at 450 to 500 ° C. Contributing to the improvement of device manufacturing efficiency is a technical issue.

As a result of diligent efforts, the present inventor is a bismuth-based sealing material containing 40 to 95% by weight of a bismuth-based glass powder and 5 to 60% by weight of a refractory filler powder. , _Bi 2 _O 3 _30~50% by _{mole%, B 2 O 3 10~ 30} %, ZnO + CuO ( total amount of ZnO and CuO) 35 to _50%, while regulating the _Fe 2 O 3 _0.1~10% The present inventors have found that the above problems can be solved by not containing PbO substantially, and propose the present invention. Here, “substantially not containing PbO” in the present invention refers to a case where the PbO content in the glass composition is 1000 ppm or less.

  The bismuth-based sealing material of the present invention contains 5 to 60% by weight of refractory filler powder. If it does in this way, the thermal expansion coefficient of a sealing material and a to-be-sealed material can be matched, an undue stress does not remain easily in the sealing layer after baking, and a sealing layer becomes difficult to carry out an impact destruction.

The bismuth-based sealing material of the present invention regulates the glass composition of bismuth-based glass as described above. That is, by containing a certain amount or more of Bi ₂ O ₃ in the bismuth glass, the softening point of the bismuth glass is lowered and the fluidity of the bismuth sealing material is improved. Further, the thermal stability of the bismuth-based sealing material is improved by setting the content of ZnO + CuO to 35 mol% or more. Thus, if the glass composition of the bismuth-based glass is regulated as described above, even if the primary firing of the sealing material and the primary firing of the phosphor are performed simultaneously, the bismuth-based sealing material is not devitrified and thereafter In this secondary firing, the bismuth-based sealing material flows well, and the production efficiency of PDP or the like can be increased.

  The bismuth-based glass according to the present invention does not substantially contain PbO. In this way, environmental demands in recent years can be satisfied.

Secondly, the bismuth-based sealing material of the present invention contains bismuth-based glass powder 40 to 95% by weight, refractory filler powder 5 to 60% by weight, and the bismuth-based glass powder has a molar composition as a glass composition. _{Bi 2 O 3 34~50%, B} 2 O 3 10~ 30%, ZnO + CuO 35~50%, contains _Fe 2 O 3 _0.1~10%, it contains substantially no PbO preferred% .

Thirdly, bismuth sealing material of the present invention, the bismuth-based glass powder, as a glass composition, the molar ratio _{Bi 2 O 3 / (ZnO +} CuO) is preferably a 0.7 to 1.1. In the bismuth-based glass according to the present invention, Bi ₂ O ₃ is a component that lowers the softening point of the glass and increases the fluidity of the bismuth-based sealing material. Thermal stability is reduced. On the other hand, ZnO + CuO is a component that enhances the thermal stability of the bismuth-based sealing material. However, if its content is large, the softening point of the glass increases and the fluidity of the bismuth-based sealing material decreases. Therefore, if the value of the molar ratio Bi ₂ O ₃ / (ZnO + CuO) is regulated as described above, the thermal stability and fluidity of the bismuth-based sealing material can be made compatible at a high level.

Fourth, bismuth sealing material of the present invention, the bismuth-based glass powder, as a glass composition, in _{mol%, BaO + SrO + MgO +} CaO 0~15%, S iO 2 + Al 2 O 3 0~10%, Sb 2 O 3 _{0~5%, WO 3 0~5%,} In 2 O 3 + Ga 2 O 3 is preferably contained 0-5%.

Fifth, in the bismuth-based sealing material of the present invention, the bismuth-based glass powder preferably contains 0.1 to 10% of CuO as a glass composition in mol%.

Sixth, in the bismuth-based sealing material of the present invention, it is preferable that the refractory filler powder does not substantially contain ZnO. Here, “substantially not containing ZnO” in the present invention refers to a case where the ZnO content in the refractory filler is 1000 ppm or less. In this way, even if the bismuth-based glass is crystalline, a part of the refractory filler dissolves in the bismuth-based glass during the primary firing of the bismuth-based sealing material, and the dissolved refractory filler becomes the bismuth-based glass. When devitrification is suppressed and the primary firing temperature is high, for example, even if the primary firing temperature is 500 ° C. or higher, devitrification is less likely to occur in the bismuth-based sealing material. That is, in this way, even if the bismuth-based glass is crystalline, the bismuth-based sealing material can exhibit an amorphous behavior during firing.

Seventh, the bismuth-based sealing material of the present invention is such that the refractory filler powder is one or more selected from cordierite, β-eucryptite, quartz glass, alumina, mullite, and alumina-silica ceramics. It is preferable that

Eighth, in the bismuth-based sealing material of the present invention, the refractory filler powder is preferably cordierite. In this way, even if the bismuth-based glass is crystalline, a portion of cordierite dissolves in the bismuth-based glass during the primary firing of the bismuth-based sealing material, and the melted cordierite becomes the bismuth-based glass. When devitrification is suppressed and the primary firing temperature is high, for example, even if the primary firing temperature is 500 ° C. or higher, devitrification is less likely to occur in the bismuth-based sealing material. That is, in this way, even if the bismuth-based glass is crystalline, the bismuth-based sealing material can exhibit an amorphous behavior during firing.

Ninth, the bismuth-based sealing material of the present invention is preferably non-crystalline (amorphous). The term “non-crystalline” as used in the present invention refers to a substance in which no crystallization peak is observed at a temperature of 600 ° C. or less by DTA (in air, temperature rising rate 10 ° C./min, measurement started from room temperature). If the bismuth-based sealing material is made non-crystalline, the bismuth-based sealing material is not easily devitrified even when fired at 450-500 ° C. after firing at 500 ° C., and the fluidity can be reliably maintained. it can.

Tenth, the bismuth-based sealing material of the present invention is preferably used for sealing a PDP. Since the bismuth-based sealing material of the present invention can simultaneously perform the primary firing of the sealing material and the primary firing of the phosphor, the production process of the PDP can be simplified. As a result, the production efficiency of the PDP can be improved. It can be improved dramatically.

  The reason why the glass composition of the bismuth glass according to the present invention is limited as described above will be described below. In addition, the following% display points out mol% unless there is particular limitation.

Bi ₂ O ₃ is a main component for lowering the softening point of glass, and its content is 30 to 50%, preferably 32 to 45%, more preferably 34 to 40%, and still more preferably 34 to 40%. 37%. When the content of Bi ₂ O ₃ is less than 30%, the softening point of the glass becomes too high and it becomes difficult to fire at a temperature of 500 ° C. or lower. On the other hand, when the content of Bi ₂ O ₃ is more than 50%, the thermal stability of the bismuth-based sealing material tends to be lowered, and the raw material cost of the glass increases.

B ₂ O ₃ is an essential component as a glass forming component, and its content is 10 to 30 %, preferably 15 to 30%, more preferably 15 to 28%, and still more preferably 18 to 23%. If the content of B ₂ O ₃ is less than 10%, the glass network is not easily formed, so that the glass is easily devitrified. On the other hand, if the content of B ₂ O ₃ is more than 30 %, the viscosity of the glass tends to increase, and it becomes difficult to fire at a temperature of 500 ° C. or lower.

  ZnO + CuO has an effect of suppressing devitrification of the glass at the time of melting, and has an effect of suppressing devitrification of the bismuth-based sealing material. ZnO and CuO should just contain at least 1 type, and content of ZnO + CuO is 35 to 50%, Preferably it is 35 to 45%. When the content of ZnO + CuO is less than 35%, it is difficult to obtain the above effect. When there is more content of ZnO + CuO than 50%, the softening point of glass will become high and it will become difficult to bake at the temperature of 500 degrees C or less.

  ZnO has an effect of suppressing devitrification of the bismuth-based sealing material, and its content is preferably 25 to 48%, more preferably 30 to 42%. When the ZnO content is less than 25%, it is difficult to obtain the effect of suppressing devitrification of the bismuth-based sealing material. On the other hand, if the ZnO content is more than 48%, the softening point of the glass becomes high and it becomes difficult to fire at a temperature of 500 ° C. or lower.

CuO is a component having an effect of suppressing devitrification of glass, and its content is preferably 0 to 10%, and more preferably 0.1 to 10%. When the content of CuO is more than 10%, the balance with other components is lacking, and conversely, the precipitation rate of crystals increases, that is, the tendency of devitrification increases, and the fluidity of the bismuth-based sealing material is poor. Furthermore, if the molar ratio Bi ₂ O ₃ / (ZnO + CuO) is restricted to 0.7 to 1.1, preferably 0.8 to 1.1, devitrification of the bismuth-based sealing material is further increased. The effect of suppressing is acquired. When the molar ratio Bi ₂ O ₃ / (ZnO + CuO) is less than 0.7, the softening point of the glass becomes high and it becomes difficult to fire at a temperature of 500 ° C. or lower. When the molar ratio Bi ₂ O ₃ / (ZnO + CuO) is greater than 1.1, it is difficult to obtain the devitrification suppressing effect of the bismuth-based sealing material.

In addition to the above components, the bismuth-based glass according to the present invention may contain the following components.
BaO, SrO, MgO and CaO are components having an effect of suppressing devitrification of the glass at the time of melting, and the total amount of these components (BaO + SrO + MgO + CaO) is preferably 0 to 15%, and 0 to 10%. More preferably. When the content of BaO + SrO + MgO + CaO exceeds 15%, the glass transition point tends to increase. The BaO content is preferably 0 to 10%. When the content of BaO is more than 10%, it becomes difficult to obtain an effect of suppressing devitrification of the glass at the time of melting. The contents of SrO, MgO and CaO are each preferably 0 to 5%. When the content of SrO, MgO and CaO is more than 5%, the balance with other components is lost, and on the contrary, the rate of crystal precipitation increases, that is, the tendency of devitrification increases, and the bismuth-based sealing material There is a tendency for fluidity to deteriorate.

Fe ₂ O ₃ is a component that suppresses devitrification of the glass at the time of melting, and its content is 0.1 to 10%, preferably 0.1 to 5%, more preferably 0.1 to 2%. It is. When the content of Fe ₂ O ₃ is more than 10%, glass tends to undergo phase separation at the time of melting.

SiO ₂ + Al ₂ O ₃ is a component that suppresses crystal precipitation of the glass and improves the water resistance of the glass during firing of the bismuth-based sealing material, and the content thereof is 0 to 10%. Is preferred. When the content of SiO ₂ + Al ₂ O ₃ is more than 10%, the softening point of the glass becomes high and it becomes difficult to fire at a temperature of 500 ° C. or lower. In particular, for the purpose of lowering the firing temperature, it is preferable to regulate the content of SiO ₂ to 0 to 6%. For the same reason, the content of Al ₂ O ₃ is preferably regulated to 0 to 6%.

WO ₃ is a component for suppressing devitrification of glass, and its content is 0 to 5%, preferably 0 to 2%. In order to lower the softening point of the bismuth-based glass, it is necessary to increase the content of the main component Bi ₂ O _3. However, if the Bi ₂ O ₃ content is increased, the bismuth-based sealing material is baked at the time of firing. In addition to the glass glass being easily devitrified, the fluidity of the bismuth-based sealing material tends to be hindered due to the devitrification. In particular, when the content of Bi ₂ O ₃ is 40% or more, the tendency becomes remarkable. Therefore, if an appropriate amount of WO ₃ is added, devitrification of the bismuth-based sealing material can be suppressed even if the Bi ₂ O ₃ content is 40% or more. On the other hand, if the content of WO ₃ is more than 5%, the balance with other components is lost, and conversely, the thermal stability of the bismuth-based sealing material tends to deteriorate.

Sb ₂ O ₃ is a component for suppressing devitrification of the glass, and its content is 0 to 5%, preferably 0 to 2%. In order to lower the softening point of the bismuth-based glass, it is necessary to increase the content of the main component Bi ₂ O _3. However, if the content of Bi ₂ O ₃ is increased, the Bi is sealed during firing of the bismuth-based sealing material. _In addition to easy precipitation of crystals containing ₂ O ₃ as a crystal component, the fluidity of the bismuth-based sealing material tends to be hindered due to the crystals. In particular, when the content of Bi ₂ O ₃ is 40% or more, the tendency becomes remarkable. Therefore, if an appropriate amount of Sb ₂ O ₃ is added, even if the Bi ₂ O ₃ content is 40% or more, the glass network of the bismuth-based glass is stabilized and devitrification of the bismuth-based sealing material is suppressed. An effect is obtained. On the other hand, when the content of Sb ₂ O ₃ is more than 5%, the balance with other components is lost, and conversely, the thermal stability of the bismuth-based sealing material tends to deteriorate.

In ₂ O ₃ + Ga ₂ O ₃ is a component for suppressing devitrification of the glass, and prevents crystals from being deposited on the bismuth-based glass during firing of the bismuth-based sealing material, thereby impairing fluidity. It is a component added for the purpose. The content of In ₂ O ₃ + Ga ₂ O ₃ is 0 to 5%, preferably 0 to 3%, more preferably 0.1 to 3%. In order to lower the softening point of the bismuth-based glass, it is necessary to increase the content of the main component Bi ₂ O _3. However, if the content of Bi ₂ O ₃ is increased, the Bi is sealed during firing of the bismuth-based sealing material. _In addition to easy precipitation of crystals containing ₂ O ₃ as a crystal component, fluidity of the bismuth-based sealing material tends to be hindered due to this devitrification. In particular, when the content of Bi ₂ O ₃ is 40% or more, the tendency becomes remarkable. Therefore, if an appropriate amount of In ₂ O ₃ + Ga ₂ O ₃ is added, an effect of suppressing devitrification of the bismuth-based sealing material can be obtained even if the Bi ₂ O ₃ content is 40% or more. On the other hand, when the content of In ₂ O ₃ + Ga ₂ O ₃ is more than 5%, the balance with other components is lacking, and conversely, the thermal stability of the bismuth-based sealing material tends to deteriorate. In particular, for the purpose of suppressing devitrification of the bismuth-based sealing material, the content of In ₂ O ₃ is preferably regulated to 0 to 4%. For the same reason, the Ga ₂ O ₃ content is preferably regulated to 0 to 4%.

Alkali metal oxides of Li ₂ O, Na ₂ O, K ₂ O and Cs ₂ O are components that lower the softening point of the glass, but since these have an action of promoting devitrification of the glass during melting, The total amount of the components is preferably 2% or less.

P ₂ O ₅ is a component that suppresses the devitrification of the glass at the time of melting. However, if the content is large, the glass is easily phase-separated at the time of melting. Therefore, the content of P ₂ O ₅ is preferably 1% or less.

MoO ₃ + La ₂ O ₃ + Y ₂ O ₃ + CeO ₂ (total amount of MoO ₃ , La ₂ O ₃ , Y ₂ O ₃ and CeO ₂ ) has an effect of suppressing the phase separation of the glass at the time of melting. When the total amount of the components is large, the softening point of the glass becomes high and it becomes difficult to fire at a temperature of 500 ° C. or lower. Therefore, the total amount of these components is preferably 3% or less.

As described above, the bismuth-based glass according to the present invention does not substantially contain PbO because of environmental requirements. Further, when PbO is contained in the bismuth-based glass, when used as an insulating material, Pb ²⁺ may diffuse into the glass and the electrical insulating property may be lowered.

  The bismuth-based glass according to the present invention can contain other components up to 10% in addition to the above components.

A suitable content range of each component can be appropriately selected to obtain a preferable glass composition range. Among them, _Bi 2 _O 3 _34~50% in _{molar%, B 2 O 3 10~ 30} %, ZnO + CuO 35~50%, 0.1~10% CuO, a _Fe 2 O 3 _0.1~10% A glass composition range that contains and substantially does not contain PbO is preferred . In this way, the thermal stability of the bismuth sealing material can be further enhanced.

The bismuth-based glass having the above glass composition can suppress devitrification when fired at 500 ° C. or higher after being mixed with a refractory filler, and is reheated to a temperature of 450 to 500 ° C. and sealed. Is possible. The bismuth glass having the above glass composition has a coefficient of thermal expansion at 30 to 300 ° C. of about 90 to 110 × 10 ⁻⁷ / ° C.

The bismuth-based sealing material of the present invention is a material whose thermal expansion coefficient is not compatible with bismuth-based glass, for example, high strain point glass (85 × 10 ⁻⁷ / ° C.), soda plate glass (90 × 10 ⁻⁷ / ° C.). When sealing such as, it is important that the thermal expansion coefficient is designed to be lower by about 10 to 30 × 10 ⁻⁷ / ° C. than the sealed object. This is to prevent the bismuth-based sealing material from being destroyed by setting the strain applied to the bismuth-based sealing material after compression to the compression (compression) side. In addition to adjusting the thermal expansion coefficient, for example, a refractory filler powder can be added to improve mechanical strength.

  When the refractory filler powder is mixed, the mixing ratio is 40 to 95% by weight for the bismuth glass powder, 5 to 60% by weight for the refractory filler powder, preferably 50 to 92% by weight for the bismuth glass powder, The filler powder is 8 to 50% by weight, more preferably 60 to 90% by weight of the bismuth glass powder and 10 to 40% by weight of the refractory filler powder. The reason for specifying the ratio of the two in this way is that when the refractory filler powder is less than 5% by weight, it becomes difficult to match the sealing material with the thermal expansion coefficient, and the bismuth-based sealing material is likely to be destroyed by residual stress. When the amount is more than 55% by weight, the fluidity of the bismuth-based sealing material is deteriorated and it is difficult to maintain the airtightness of a flat display device or the like.

  Refractory filler powder is required to have low reactivity to the extent that thermal stability does not decrease even when added to bismuth-based glass powder, and depending on the application, low thermal expansion coefficient and high mechanical strength are required. Is done. Further, as the refractory filler powder, it is preferable to use a refractory filler powder substantially not containing PbO because of environmental demands. The refractory filler powder is preferably a refractory filler powder containing no ZnO, and is one or more selected from cordierite, β-eucryptite, quartz glass, alumina, mullite, and alumina-silica ceramics. Is preferred. These refractory filler powders have good compatibility with bismuth-based glass and have a property that it is difficult to reduce the thermal stability of the bismuth-based sealing material. In particular, cordierite is a part of cordierite that melts into bismuth glass during the primary firing of the bismuth-based sealing material, and the melted cordierite suppresses devitrification of the bismuth glass, and the primary firing temperature is reduced. When the temperature is high, for example, even if the primary firing temperature is 500 ° C. or higher, devitrification hardly occurs in the bismuth-based sealing material. Furthermore, cordierite has characteristics of low expansion and excellent mechanical strength.

  The refractory filler powder is preferably coated with alumina, zinc oxide, zircon, titania, zirconia, or the like because the reaction between the bismuth glass powder and the refractory filler powder can be adjusted.

  The bismuth-based sealing material having the above-described structure does not devitrify even when subjected to primary firing at 500 ° C., and can effectively avoid a situation in which crystals grow during the subsequent secondary firing, and is required for secondary firing. Can be ensured. Therefore, it can be said that the bismuth-based sealing material of the present invention is a non-crystalline (amorphous) glass having high thermal stability and hardly causing devitrification by multiple heat treatments.

  The bismuth-based sealing material of the present invention has been described mainly for PDP applications, but it goes without saying that it can be suitably used for other applications that undergo a plurality of heat treatment steps. Specific applications include (I) PDP insulating layer and dielectric layer forming materials, (II) VFD insulating layer forming materials, and (III) magnetic head-core or core-slider sealing. Can be mentioned.

  The bismuth-based sealing material of the present invention may be used in a powder state, but is easy to handle when the bismuth-based sealing material and the vehicle are uniformly kneaded and used as a paste. The vehicle is mainly composed of an organic solvent and a resin, and the resin is added for the purpose of adjusting the viscosity of the paste. Moreover, surfactant, a thickener, etc. can also be added as needed. The produced paste is applied using an applicator such as a dispenser or a screen printer.

  As organic solvents, N, N′-dimethylformamide (DMF), α-terpineol, higher alcohol, γ-butyllactone (γ-BL), tetralin, butyl carbitol acetate, ethyl acetate, isoamyl acetate, diethylene glycol monoethyl ether , Diethylene glycol monoethyl ether acetate, benzyl alcohol, toluene, 3-methoxy-3-methylbutanol, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, Tripropylene glycol monobutyl ether, propylene carbonate, dimethyl sulfoxide (DMSO), N Methyl-2-pyrrolidone and the like can be used. In particular, α-terpineol is preferable because it is highly viscous and has good solubility in resins and the like.

  As the resin, acrylic resin, ethyl cellulose, polyethylene glycol derivative, nitrocellulose, polymethylstyrene, polyethylene carbonate, methacrylic acid ester and the like can be used. In particular, acrylic resin and nitrocellulose are preferable because they have good thermal decomposability.

  Hereinafter, the present invention will be described in detail based on examples.

Tables 1 to 3 show bismuth-based glass compositions (samples A to H, J) according to examples of the present invention and bismuth-based glass compositions (samples K to M) according to comparative examples of the present invention. Sample I is a reference example.

Each sample described in Tables 1 to 3 was prepared as follows.

First, a glass batch in which raw materials such as various oxides and carbonates were prepared so as to have the glass composition shown in the table was prepared, and this was put in a platinum crucible and melted at 900 to 1100 ° C. for 1 to 2 hours. Next, a part of the molten glass was poured out into a stainless steel mold as a sample for measuring the coefficient of thermal expansion, and the other molten glass was formed into a thin piece with a water-cooled roller. Finally, the glass flakes were pulverized with a ball mill and passed through a sieve having a mesh size of 105 mesh to obtain samples having an average particle diameter D _{50 of} 10 μm.

  The glass transition point, softening point, and thermal expansion coefficient were evaluated using the above samples.

  The softening point was determined by DTA.

  The glass transition point was determined by a TMA apparatus. The thermal expansion coefficient was measured in a temperature range of 30 to 380 ° C. using a TMA apparatus.

As is apparent from Tables 1 to 3, samples A to J according to the examples of the present invention have a glass transition point of 332 to 355 ° C., a softening point of 418 to 435 ° C., and a thermal expansion coefficient at 100 to 30 ° C. of 100. a ~112 × 10 ^-7 / ℃, sample K~M according to a comparative example of the present invention has a glass transition point of three hundred and forty-seven to three hundred sixty-three ° C., a softening point of 418 to 425 ° C., the thermal expansion coefficient at 30 to 380 ° C. It was 96-112 * 10 < ^-7 > / degreeC.

Samples A to M and refractory filler powder were mixed at the ratios shown in Tables 4 to 6 to prepare bismuth-based sealing materials. Tables 4 to 6 show bismuth-based sealing materials (sample Nos. 1 to 9 and 11) which are examples of the present invention and bismuth-based sealing materials (samples 12 to 14) which are comparative examples of the present invention. Show. Sample No. Reference numeral 10 is a reference example.

Sample No. 1-4 and 14 are bismuth sealing materials for sealing a soda glass substrate for VFD (thermal expansion coefficient 90 × 10 ⁻⁷ / ° C.). Sample No. 5 to 13 are bismuth-based sealing materials for sealing a high strain point glass substrate for PDP (thermal expansion coefficient 85 × 10 ⁻⁷ / ° C.).

Cordierite powder having an average particle diameter D ₅₀ of 10 μm was used as the refractory filler powder.

  Using the above samples, the thermal expansion coefficient, flow diameter, devitrification state, and resealability were evaluated.

  The thermal expansion coefficient was measured in a temperature range of 30 to 380 ° C. using a TMA apparatus.

  The flow diameter was dry-pressed with a die having a weight corresponding to the true specific gravity of the bismuth-based sealing material into a button shape having an outer diameter of 20 mm, and the button sample was put into an air-flow electric furnace and then 10 in air. The temperature was raised at a rate of ° C./minute, held at the temperature shown in the table for 10 minutes, then lowered to room temperature at a rate of 10 ° C./minute, and the diameter of the fired button obtained was evaluated. In addition, it is meaning that fluidity | liquidity is favorable in a flow diameter being 20 mm or more.

  The devitrification state and resealability were evaluated as follows.

  First, each sample and vehicle (acrylic resin-containing α-terpineol) were uniformly kneaded with a three-roll mill and formed into a paste, and then a substrate (40 × 40 × 2.8 mm) to be sealed for each sample. The film was applied linearly (length 40 × width 3 × 1.5 mm thickness) to the end of the (thickness) and dried at 130 ° C. for 15 minutes in a drying oven. Next, the temperature was raised from room temperature at 10 ° C./minute, the substrate was baked at 500 ° C. for 30 minutes, and then the temperature was lowered to room temperature at 10 ° C./minute. Subsequently, after placing a glass plate (glass spacer) having a thickness of 150 μm at the center of the substrate and covering the same size substrate, both substrates are fixed with clips and fired under the firing conditions in the table. did. The firing was performed at a temperature raising / lowering rate of 10 ° C./min.

  The devitrification state was evaluated by observing the surface of the obtained fired body, and “◯” indicates that no crystal was observed on the surface, and “X” indicates that crystal was observed on the surface.

  The resealability was evaluated as “◯” when the bismuth-based sealing material flowed by firing and the distance between the substrates was 150 μm, and “×” when the distance was larger than 150 μm. In addition, it is thought that the sample of evaluation of "(circle)" was not devitrified by the 1st baking (500 degreeC for 30 minutes).

As is clear from Tables 4-6, Sample No. The bismuth-based sealing material of 1 to 11 had a thermal expansion coefficient of 68.7 to 78.0 × 10 ⁻⁷ / ° C. at 30 to 380 ° C. Further, no crystals were precipitated under the firing conditions described in the table, and the resealability was good.

  On the other hand, Sample No. The bismuth-based sealing materials of 12 to 14 had poor resealability in addition to the precipitation of crystals under the firing conditions described in the table. Sample No. The reason why the resealability of 12 to 14 bismuth-based sealing materials was poor is that crystals were already deposited by the first firing. Sample No. Since the total composition of ZnO + CuO is less than 35% in the bismuth glass according to Nos. 12 and 13, the bismuth-based sealing material has already been devitrified by firing at 500 ° C. for 30 minutes, and the bismuth-based glass is obtained in the second firing. It is considered that crystals precipitated on the glass further grew and the fluidity of the bismuth-based sealing material was impaired. Sample No. Since the total amount of ZnO + CuO of the bismuth glass according to No. 14 is more than 50%, the bismuth-based sealing material has already been devitrified by firing at 500 ° C. for 30 minutes, and the bismuth-based glass is obtained by the second firing. It is considered that the precipitated crystals further grew and the fluidity of the bismuth-based sealing material was impaired.

  As described above, the bismuth-based sealing material of the present invention is suitable for sealing flat display devices such as PDP, FED, and VFD, and sealing electronic parts such as crystal resonators and IC packages. The bismuth-based sealing material of the present invention includes (I) a PDP insulating layer and dielectric layer forming material, (II) a VFD insulating layer forming material, and (III) magnetic head-cores or core and slider. It can be used as a sealing material.

Claims (10)

A bismuth-based sealing material containing 40 to 95% by weight of a bismuth-based glass powder and 5 to 60% by weight of a refractory filler powder, wherein the bismuth-based glass powder has a glass composition of Bi ₂ O ₃ 30 in mol%. _{~50%, B 2 O 3 10~} 30%, ZnO + CuO 35~50%, Fe 2 O 3 containing 0.1% to 10%, and substantially bismuth-based sealing, characterized in that do not contain PbO material. A bismuth-based sealing material containing 40 to 95% by weight of a bismuth-based glass powder and 5 to 60% by weight of a refractory filler powder, wherein the bismuth-based glass powder has a glass composition of Bi ₂ O ₃ 34 in mol%. _{~50%, B 2 O 3 10~} 30%, ZnO + CuO 35~50%, contains _Fe 2 O 3 _0.1~10%, and substantially in claim 1, characterized in that do not contain PbO The bismuth-based sealing material described. The bismuth-based sealing material according to claim 1 or 2, wherein the bismuth-based glass powder has a glass composition having a molar ratio Bi ₂ O ₃ / (ZnO + CuO) of 0.7 to 1.1. . Bismuth glass powder, as a glass composition, in _{mole%, BaO + SrO + MgO +} CaO 0~15%, S iO 2 + Al 2 O 3 0~10%, Sb 2 O 3 0~5%, WO 3 0~5%, In 2 The bismuth-based sealing material according to any one of claims 1 to _{3, comprising} 0 to 5% of O ₃ + Ga ₂ O ₃ .   The bismuth-based sealing material according to any one of claims 1 to 4, wherein the bismuth-based glass powder contains 0.1 to 10% of CuO as a glass composition in mol%.   The bismuth-based sealing material according to any one of claims 1 to 5, wherein the refractory filler powder does not substantially contain ZnO.   The refractory filler powder is one or more selected from cordierite, β-eucryptite, quartz glass, alumina, mullite, and alumina-silica ceramics. A bismuth-based sealing material according to any one of the above.   The bismuth-based sealing material according to any one of claims 1 to 7, wherein the refractory filler powder is cordierite.   The bismuth-based sealing material according to any one of claims 1 to 8, which is non-crystalline.   The bismuth-based sealing material according to claim 1, which is used for sealing a plasma display panel.