JP6075715B2 - Bismuth glass and sealing material using the same - Google Patents

Description

  The present invention relates to bismuth-based glass and a sealing material using the same, and more particularly to a bismuth-based glass suitable for sealing treatment with laser light (hereinafter referred to as laser sealing) and a sealing material using the same.

  In recent years, organic EL displays have attracted attention as flat display panels. Since the organic EL display can be driven by a direct current voltage, the driving circuit can be simplified, and there are advantages such as a liquid crystal display that is not dependent on the viewing angle, bright due to self-emission, and has a high response speed. Currently, organic EL displays are mainly used in small portable devices such as mobile phones, but in the future, application to ultra-thin televisions is expected. Note that the organic EL display is mainly driven by disposing an active element such as a thin film transistor (TFT) in each pixel in the same manner as a liquid crystal display.

  The organic EL display is composed of two glass substrates, a negative electrode such as metal, an organic light emitting layer, a positive electrode such as ITO, and an adhesive material. Conventionally, an organic resin adhesive material such as an epoxy resin having a low temperature curability or an ultraviolet curable resin has been used as the adhesive material. However, organic resin adhesive materials cannot completely block gas intrusion. For this reason, when an organic resin adhesive material is used, the airtightness inside the organic EL display cannot be maintained, and as a result, the organic light emitting layer having low water resistance is easily deteriorated, and the organic EL display There was a problem that the display characteristics of the display deteriorated with time. In addition, the organic resin-based adhesive material has an advantage that the glass substrates can be bonded to each other at a low temperature. However, since the water resistance is low, when the organic EL display is used for a long time, the reliability of the display is likely to be lowered. .

  On the other hand, the sealing material containing glass powder is excellent in water resistance as compared with the organic resin-based adhesive material, and is suitable for ensuring airtightness inside the organic EL display.

  However, since glass powder generally has a softening temperature of 300 ° C. or higher, it has been difficult to apply it to an organic EL display. More specifically, when sealing glass substrates with the above-mentioned sealing material, the entire organic EL display is put into an electric furnace and baked at a temperature equal to or higher than the softening temperature of the glass powder to soften and flow the glass powder. It was necessary to let them. However, since the active element used in the organic EL display has only heat resistance of about 120 to 130 ° C., sealing the glass substrates by this method damages the active element due to heat, and the organic EL display. Display characteristics will deteriorate. In addition, since the organic light emitting material also has poor heat resistance, sealing the glass substrates by this method damages the organic light emitting material due to heat and degrades the display characteristics of the organic EL display.

  In view of such circumstances, in recent years, laser sealing has been studied as a method for sealing an organic EL display. According to laser sealing, since only the portion to be sealed can be locally heated, it is possible to seal the glass substrates together while preventing thermal degradation of the active element or the like.

US Pat. No. 6,416,375 JP 2006-315902 A

  Patent Documents 1 and 2 describe laser-sealing glass substrates of a field emission display. However, Patent Documents 1 and 2 do not describe a specific material configuration, and it is unclear what material configuration is suitable for laser sealing. For this reason, even if the sealing material is irradiated with the laser beam, the sealing material cannot absorb the laser beam accurately, and it is difficult to efficiently convert the laser beam into heat energy at the portion to be sealed. It was. If the output of the laser beam is increased, laser sealing can be performed without optimizing the material structure. In this case, however, the active element or the like may be heated to deteriorate the display characteristics of the organic EL display. is there.

  Further, according to the investigation by the present inventors, the fluidity of the sealing material is required for laser sealing. When the fluidity of the sealing material is high, the sealing strength is improved, and airtight defects such as leaks are less likely to occur due to mechanical impact or the like.

  Further, according to the investigation by the present inventors, it is also required to lower the melting point of the sealing material for laser sealing. If the melting point of the sealing material is lowered, the sealed portion is hardly broken by the thermal shock of local heating.

  Therefore, the present invention has been made in view of the above circumstances, and its technical problem is to easily convert laser light into thermal energy, exhibit good fluidity, and contribute to lowering the melting point, and bismuth glass. It is to improve long-term reliability of an organic EL device or the like by providing a sealing material using this.

The present inventors adopt a bismuth-based glass containing a large amount of Bi ₂ O ₃ and can introduce the predetermined amount of CuO and / or Fe ₂ O ₃ into the glass composition to solve the above technical problem. It is proposed as a heading and the present invention. That is, the bismuth-based glass of the present invention has a glass composition represented by mass% in terms of the following oxide, Bi ₂ O ₃ 70 to 90%, B ₂ O ₃ 2 to 12%, ZnO 1 to 15%, CuO + Fe _2. It is characterized by containing 0.2 to 15% of O _{3 and} 0.1 to 20% of MgO + CaO + SrO + BaO. Here, “CuO + Fe ₂ O ₃ ” is the total amount of CuO and Fe ₂ O ₃ . “MgO + CaO + SrO + BaO” is the total amount of MgO, CaO, SrO and BaO.

  Bismuth-based glass has a feature that it is difficult to foam during laser sealing compared to other glass-based glasses. For this reason, when bismuth-type glass is used, the situation where the mechanical strength of a sealing part falls due to foaming can be prevented. Furthermore, bismuth-based glass has a feature that it has higher thermal stability than other glass-based glasses. For this reason, when bismuth-based glass is used, it is possible to prevent the sealing strength from being reduced due to devitrification during laser sealing.

  Moreover, if the glass composition range of bismuth-type glass is regulated as described above, the softening point can be lowered while maintaining thermal stability. As a result, good fluidity can be secured at a low temperature (500 ° C. or lower, preferably 480 ° C. or lower, more preferably 450 ° C. or lower).

Further, the bismuth-based glass of the present invention contains CuO + Fe ₂ O ₃ in an amount of 0.2% by mass or more (preferably 1% by mass or more, more preferably 2% by mass or more, still more preferably 3% by mass or more, particularly preferably 4% by mass. % Or more, most preferably 5% by mass or more). If it does in this way, a laser beam etc. will be efficiently converted into thermal energy and only the part which should be sealed can be heated locally. As a result, it is possible to seal the glass substrates together while preventing the active element and the organic light emitting layer from being thermally damaged. In the case of laser sealing, the temperature at a site 1 mm away from the irradiation site is 100 ° C. or lower, and thermal damage to the active element and the organic light emitting layer can be prevented. On the other hand, in the bismuth-based glass of the present invention, the content of CuO + Fe ₂ O ₃ is regulated to 15% by mass or less. If it does in this way, it will become difficult to devitrify glass at the time of laser sealing.

Second, the bismuth-based glass of the present invention preferably has a CuO + Fe ₂ O ₃ content of 4% by mass or more.

  Third, the bismuth-based glass of the present invention preferably has a molar ratio BaO / ZnO value of 0.01-2.

Fourth, the bismuth-based glass of the present invention preferably has a molar ratio Bi ₂ O ₃ / B ₂ O ₃ of 1.6 or more.

Fifth, the bismuth-based glass of the present invention preferably has a molar ratio Bi ₂ O ₃ / ZnO of 1.55 or more.

  Sixth, the bismuth-based glass of the present invention preferably has a BaO content of 0.1% by mass or more. If it does in this way, thermal stability and low temperature sealing property can be improved.

Seventh, the bismuth-based glass of the present invention has a CuO + Fe ₂ O ₃ content of 5 mass% or more, a molar ratio Bi ₂ O ₃ / B ₂ O ₃ of 1.5 or less, and a molar ratio BaO / ZnO. The value of is preferably 0.7 or more. In this way, both low melting point characteristics and thermal stability can be achieved at a high level, and when laser light is irradiated onto the glass, the laser light is converted into thermal energy with high efficiency, so that the glass is sufficiently softened. It can flow and can improve the sealing strength between glass substrates.

  Eighth, the sealing material of the present invention is characterized in that it contains 55 to 100% by volume of glass powder made of the above bismuth glass and 0 to 45% by volume of refractory filler powder. In this way, the thermal expansion coefficient of the sealing material can be lowered so as to match the thermal expansion coefficient of the object to be sealed.

  Ninthly, in the sealing material of the present invention, the refractory filler powder is preferably one or more selected from cordierite, willemite, alumina, zirconium phosphate, zircon, zirconia, and tin oxide.

  10thly, it is preferable that the sealing material of this invention does not contain PbO substantially. Here, “substantially does not contain PbO” refers to a case where the content of PbO in the sealing material is less than 1000 ppm (mass). In this way, environmental demands in recent years can be satisfied.

  Eleventh, the sealing material of the present invention preferably has a softening point of 500 ° C. or lower. If the softening point is too high, the glass does not sufficiently soften and flow even when irradiated with laser light, and it is necessary to increase the output of the laser light in order to increase the sealing strength between the glass substrates. If the output of the laser beam is high, the thermal shock between the laser beam irradiation part and the non-irradiation part becomes large at the time of laser sealing, and cracks and the like are likely to occur in the sealing part. Here, the “softening point” refers to a value measured with a macro-type differential thermal analysis (DTA) apparatus, DTA starts measurement from room temperature, and the rate of temperature rise is 10 ° C./min. In addition, the softening point measured with the macro type | mold DTA apparatus points out the temperature (Ts) of the 4th bending point shown in FIG. In addition, although the minimum of a softening point is not specifically limited, If the thermal stability of the said bismuth-type glass is considered, 390 degreeC or more is preferable.

Twelfth, the sealing material of the present invention is preferably used for laser sealing. If it does in this way, a sealing material can be heated locally and the thermal damage of an active element or an organic light emitting layer can be prevented. The type of laser light source is not particularly limited. For example, a semiconductor laser, a YAG laser, a CO ₂ laser, an excimer laser, an infrared laser, and the like are preferable in terms of easy handling. In addition, the emission center wavelength is preferably 500 to 1600 nm, particularly preferably 750 to 1300 nm, in order for the bismuth-based glass to absorb laser light accurately.

  Thirteenth, the sealing material of the present invention is preferably used for sealing an organic EL device or a solar cell.

It is outline data which shows the softening point (Ts) when it measures with a macro type DTA apparatus.

  The reason for limiting the glass composition range of the bismuth-based glass of the present invention is shown below. In addition, the following% display points out the mass% except the case where there is particular notice.

Bi ₂ O ₃ is a main component for lowering the softening point, and its content is 70 to 90%, preferably 75 to 90%, more preferably 80 to 90%, still more preferably 82 to 88%. . If the content of Bi ₂ O ₃ is less than 70%, the softening point becomes too high, and the glass is difficult to soften even when irradiated with laser light or the like. On the other hand, when the content of Bi ₂ O ₃ is more than 90%, the glass becomes thermally unstable, and the glass is easily devitrified at the time of melting or irradiation.

B ₂ O ₃ is a component that forms a glass network of bismuth-based glass, and its content is 2 to 12%, preferably 3 to 10%, and more preferably 3 to 8%. If the content of B ₂ O ₃ is less than 2%, the glass becomes thermally unstable, and the glass tends to devitrify during melting or irradiation. On the other hand, if the content of B ₂ O ₃ is more than 12%, the softening point becomes too high, and the glass is difficult to soften even when irradiated with laser light or the like.

The value of the molar ratio Bi ₂ O ₃ / B ₂ O ₃ is preferably 1.6 or more, 1.65 or more, 1.9 or more, particularly 2.5 or more. If the value of the molar ratio Bi ₂ O ₃ / B ₂ O ₃ is too small, the softening point becomes too high, and the glass is difficult to soften even when irradiated with laser light or the like. Incidentally, when the content of CuO + _Fe 2 _{O 3} is large, for example, when the content of CuO + _Fe 2 _{O 3} is more than 5 mass%, the value of the molar ratio _{Bi 2 O 3 / B 2 O} 3 is too large, the glass It becomes thermally unstable and the glass tends to be devitrified during melting or irradiation. Therefore, in that case, the value of the molar ratio Bi ₂ O ₃ / B ₂ O ₃ is preferably 2.3 or less, 2.0 or less, 1.8 or less, 1.7 or less, 1.6 or less, particularly 1. 5 or less.

  ZnO is a component that suppresses devitrification at the time of melting or irradiation and lowers the thermal expansion coefficient, and its content is 1 to 15%, preferably 1.5 to 10%. If the ZnO content is less than 1%, the devitrification suppressing effect at the time of melting or irradiation becomes poor. On the other hand, when the content of ZnO is more than 15%, the component balance in the glass composition is impaired, and conversely, the glass is easily devitrified.

The value of the molar ratio Bi ₂ O ₃ / ZnO is preferably 1.55 or more, 1.6 to 10, 3 to 9.5, 4 to 9, 5 to 8.5, particularly 5.5 to 8. In this way, both low melting point characteristics and thermal stability can be achieved at a high level.

  MgO + CaO + SrO + BaO is a component that suppresses devitrification during melting or irradiation. The content of MgO + CaO + SrO + BaO is 0.1 to 20%, preferably 0.1 to 15%, more preferably 0.1 to 10%. If the content of MgO + CaO + SrO + BaO is more than 20%, the softening point becomes too high, and the glass becomes difficult to soften even when irradiated with laser light or the like.

  The content of BaO is 0.1 to 15%, preferably 0.1 to 8%. If the content of BaO is more than 15%, the softening point becomes too high, and the glass is difficult to soften even when irradiated with laser light or the like. The content of each of MgO, CaO, and SrO is preferably 0 to 5%, particularly preferably 0 to 2%. If the content of each of MgO, CaO, and SrO is too large, the softening point becomes too high, and the glass is difficult to soften even when irradiated with laser light or the like.

  The value of the molar ratio BaO / ZnO is preferably 0.01-2, 0.03-1.5, 0.05-1.2, 0.1-0.9, 0.4-0.9, in particular 0.7-0.9. In this way, both low melting point characteristics and thermal stability can be achieved at a high level.

CuO + Fe ₂ O ₃ is a component having light absorption characteristics, and is a component that, when irradiated with light having a predetermined emission center wavelength, absorbs light and softens the glass easily. CuO + Fe ₂ O ₃ is a component that suppresses devitrification at the time of melting or irradiation. The content of CuO + Fe ₂ O ₃ is 0.2 to 15%, preferably 1 to 10%, more preferably 2 to 9%, still more preferably 3 to 8%, particularly preferably 4 to 8%, and most preferably 5 ~ 8%. When the content of CuO + Fe ₂ O ₃ is less than 0.2%, the light absorption characteristics are poor, and the glass is difficult to soften even when irradiated with laser light or the like. On the other hand, when the content of CuO + Fe ₂ O ₃ is more than 15%, the component balance in the glass composition is impaired, and conversely, the glass is easily devitrified, and the fluidity is easily lowered.

  CuO is a component having light absorption characteristics. That is, it is a component that, when irradiated with light having a predetermined emission center wavelength, absorbs light and softens the glass easily. Furthermore, it is a component that suppresses devitrification during melting or irradiation. The content of CuO is preferably 0 to 15%, 0.2 to 10%, 1 to 9%, particularly 3 to 7%. When the content of CuO is more than 15%, the component balance in the glass composition is impaired, and conversely, the glass is easily devitrified, and the fluidity is easily lowered. In addition, when there is little content of CuO, a light absorption characteristic will become scarce and even if it irradiates a laser beam etc., it will become difficult to soften glass.

Fe ₂ O ₃ is a component having light absorption characteristics. That is, it is a component that, when irradiated with light having a predetermined emission center wavelength, absorbs light and softens the glass easily. Furthermore, it is a component that suppresses devitrification during melting or irradiation. The content of Fe ₂ O ₃ is preferably 0 to 7%, 0.05 to 7%, 0.1 to 4%, particularly 0.2 to 2%. When the content of Fe ₂ O ₃ is more than 7%, is impaired balance of components in the glass composition, reverse glass becomes liable to devitrify, the fluidity tends to decrease. Incidentally, when the content of Fe ₂ O ₃ is small, the light absorption characteristic is poor, even when irradiated with a laser beam or the like, a glass is hardly softened.

It is assumed that Fe in the glass composition exists in the form of Fe ²⁺ or Fe ³⁺ , but in the present invention, Fe in the glass composition is not limited to either Fe ²⁺ or Fe ^3+. Any of these may be used. Therefore, in the present invention, the case of Fe ²⁺ is handled after being converted to Fe ₂ O ₃ . In particular, when an infrared laser is used, since Fe ²⁺ has an absorption peak in the infrared region, it is preferable to increase the ratio of Fe ²⁺ , and the ratio of Fe ²⁺ / Fe ³⁺ is preferably 0.03 or more (preferably 0.8. (08 or more) is preferable.

  In addition to the above components, for example, the following components may be added. The total amount added is preferably 20% or less, 10% or less, and particularly preferably 5% or less.

SiO ₂ is a component that improves water resistance. The content is preferably 0 to 10%, particularly preferably 0 to 3%. When the content of SiO ₂ is more than 10%, the softening point becomes too high, and the glass is difficult to soften even when irradiated with laser light or the like.

Al ₂ O ₃ is a component that improves water resistance. Its content is preferably 0 to 5%, particularly preferably 0.1 to 2%. When the content of Al ₂ O ₃ is more than 5%, the softening point becomes too high and the glass is difficult to soften even when irradiated with laser light or the like.

CeO ₂ is a component that suppresses devitrification during melting or irradiation. The CeO ₂ content is preferably 0 to 5%, 0 to 2%, particularly preferably 0 to 1%. When the content of CeO ₂ is too large, is impaired balance of components in the glass composition, the glass is liable to devitrify reversed.

Sb ₂ O ₃ is a component that suppresses devitrification. The content of Sb ₂ O ₃ is preferably 0 to 5%, 0 to 2%, particularly preferably 0 to 1%. Sb ₂ O ₃ has an effect of stabilizing the network structure of the bismuth-based glass. If Sb ₂ O ₃ is added appropriately, the content of Bi ₂ O ₃ is large, for example, the content of Bi ₂ O ₃ is Even if it is 76% or more, thermal stability becomes difficult to fall. However, when the content of Sb ₂ O ₃ is too large, is impaired balance of components in the glass composition, the glass is liable to devitrify reversed.

Nd ₂ O ₃ is a component that suppresses devitrification. The content of Nd ₂ O ₃ is preferably 0 to 5%, 0 to 2%, particularly preferably 0 to 1%. Nd ₂ O ₃ has an effect of stabilizing the network structure of bismuth-based glass. If Nd ₂ O ₃ is added appropriately, the content of Bi ₂ O ₃ is large, for example, the content of Bi ₂ O ₃ is Even if it is 76% or more, thermal stability becomes difficult to fall. However, when the content of Nd ₂ O ₃ is too large, is impaired balance of components in the glass composition, the glass is liable to devitrify reversed.

WO ₃ is a component that suppresses devitrification. The content of WO ₃ is preferably 0 to 10%, in particular 0 to 2%. However, when the content of WO ₃ is too large, is impaired balance of components in the glass composition, the glass is liable to devitrify reversed.

In ₂ O ₃ + Ga ₂ O ₃ (total amount of In ₂ O ₃ and Ga ₂ O ₃ ) is a component that suppresses devitrification. The content of In ₂ O ₃ + Ga ₂ O ₃ is preferably 0 to 5%, particularly 0 to 3%. _However, when the content of _{In 2 O 3 + Ga 2 O} 3 is too large, is impaired balance of components in the glass composition, the glass is liable to devitrify reversed. In addition, the content of In ₂ O ₃ is preferably 0 to 1%, and the content of Ga ₂ O ₃ is preferably 0 to 0.5%.

Li ₂ O, Na ₂ O, K ₂ O, and Cs ₂ O are components that lower the softening point, but have a function of promoting devitrification at the time of melting. Therefore, the total content of these components is preferably 2% or less.

P ₂ O ₅ is a component that suppresses devitrification at the time of melting. If the amount of P ₂ O ₅ added is more than 1%, the glass is likely to undergo phase separation at the time of melting.

La ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O ₃ are components that suppress phase separation at the time of melting, but if the content of each component is more than 3%, the softening point becomes too high, and laser Even if light or the like is irradiated, the glass becomes difficult to soften.

NiO, V ₂ O ₅ , CoO, MoO ₃ , TiO ₂ and MnO ₂ are components having light absorption characteristics. That is, it is a component that, when irradiated with light having a predetermined emission center wavelength, absorbs light and softens the glass easily. The content of each component is preferably 0-7%, in particular 0-3%. When there is too much content of each component, fluidity | liquidity will fall easily by devitrification.

  As described above, it is preferable that PbO is not substantially contained from an environmental viewpoint.

  The bismuth-based glass has good weather resistance, high thermal stability, and good fluidity at low temperatures. As a result, airtightness of the organic EL device or the like can be ensured over a long period of time.

  The sealing material of the present invention contains 55 to 100% by volume of glass powder made of the bismuth-based glass and 0 to 45% by volume of refractory filler powder, preferably 60 to 100% by volume of bismuth-based glass powder, and refractory filler. It is 0-40 volume% of powder, More preferably, it is 60-85 volume% of bismuth-type glass powder, and 15-40 volume% of refractory filler powders. Since the bismuth-based glass has a low melting point, it flows well at low temperatures. Further, when a refractory filler powder is added to the bismuth-based glass powder, the thermal expansion coefficient of the sealing material can be adjusted, so that the thermal expansion coefficient of the sealed object can be easily matched. As a result, it is possible to prevent a situation in which undue stress remains at the sealing portion. However, when the content of the refractory filler powder is more than 45% by volume, the content of the bismuth-based glass powder is relatively reduced, and it becomes difficult to ensure desired fluidity.

  The refractory filler powder is preferably one or more selected from cordierite, willemite, alumina, zirconium phosphate, zircon, zirconia, and tin oxide. These refractory filler powders have a low coefficient of thermal expansion, a high mechanical strength, and good compatibility with bismuth-based glass powders. Furthermore, in addition to the above refractory filler powders, refractory filler powders such as quartz glass and β-eucryptite are used for adjustment of the thermal expansion coefficient of the sealing material, adjustment of fluidity and improvement of mechanical strength. Can be added.

As the glass substrate for an organic EL device, an alkali-free glass substrate (for example, OA-10G manufactured by Nippon Electric Glass Co., Ltd.) is usually used. The coefficient of thermal expansion of the alkali-free glass substrate is usually 40 × 10 ⁻⁷ / ° C. or less. When sealing alkali-free glass substrates together, it is necessary to match the thermal expansion coefficient of the sealing material to the alkali-free glass substrate. Therefore, it is important to reduce the thermal expansion coefficient of the sealing material as much as possible, and the thermal expansion coefficient of the sealing material is preferably 80 × 10 ⁻⁷ / ° C. or less, particularly preferably 70 × 10 ⁻⁷ / ° C. or less. . By doing so, since the stress applied to the sealed portion is reduced, it becomes easy to prevent stress destruction of the sealed portion. Here, the “thermal expansion coefficient” refers to a value measured with a push rod type thermal expansion coefficient measurement (TMA) apparatus, and the measurement temperature range is 30 to 300 ° C.

  In the sealing material of the present invention, the softening point is preferably 480 ° C. or lower, 450 ° C. or lower, and particularly preferably 430 ° C. or lower. If the softening point is too high, the glass tends to be difficult to soften even when irradiated with laser light or the like, and in order to increase the sealing strength between the glass substrates, it is necessary to increase the output of the laser light or the like.

In the sealing material of the present invention, the maximum particle diameter _Dmax of the refractory filler powder is preferably 15 μm or less, less than 10 μm, less than 5 μm, particularly preferably less than 3 μm. If the maximum particle diameter _Dmax of the refractory filler powder is too large, it is difficult to make the gap between the glass substrates uniform, and it is difficult to make the organic EL device thin. Further, if the maximum particle diameter _Dmax of the refractory filler powder is too large, the gap between the two glass substrates becomes large. In such a case, even if the difference in thermal expansion coefficient between the glass substrate and the sealing material is large, the glass substrate In addition, cracks and the like are less likely to occur at the sealed portion. Here, the “maximum particle diameter D _max ” refers to a value measured by a laser diffractometer, and in the volume-based cumulative particle size distribution curve measured by the laser diffraction method, the accumulated amount is accumulated from the smaller particle. The particle size is 99%.

In the sealing material of the present invention, the maximum particle diameter _Dmax of the bismuth-based glass powder is preferably 10 μm or less, particularly preferably 5 μm or less. If the maximum particle diameter _Dmax of the bismuth-based glass powder is too large, it becomes difficult to narrow the gap between the two glass substrates. In this case, the time required for laser sealing can be shortened, and the heat of the glass substrate and the sealing material can be reduced. Even if the difference in the expansion coefficient is large, cracks and the like are hardly generated in the glass substrate and the sealing portion.

  The sealing material of the present invention may be used in a powder state, but is easy to handle when it is uniformly kneaded with a vehicle and processed into a paste. The vehicle is mainly composed of a solvent and a resin. 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 to a glass substrate using an applicator such as a dispenser or a screen printer, and is subjected to a binder removal process.

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

  As a solvent, 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.

  The present invention will be described in detail based on examples. Tables 1 and 2 show examples of the present invention (sample Nos. 1 to 8) and comparative examples (samples No. 9 and 10). The following examples are merely illustrative. The present invention is not limited to the following examples.

Each sample described in the table 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 in the table was prepared, and this was put in a platinum crucible and melted at 1000 to 1100 ° C. for 1 hour. Next, the obtained molten glass was formed into a thin piece with a water-cooled roller. Finally, after grinding the flaky glass ball mill, and air classification, the average particle diameter _{D 50} of 2.5 [mu] m, maximum particle diameter _{D max} to obtain each glass powder of 10 [mu] m.

Cordierite, willemite, β-eucryptite and zirconium phosphate were used as the refractory filler powder. Each refractory filler powder has an average particle diameter D ₅₀ adjusted to 2.5 μm and a maximum particle diameter D _max adjusted to 10 μm by air classification. The maximum particle diameter _Dmax is preferably less than 10 μm, less than 5 μm, particularly preferably less than 3 μm, as described above.

  As shown in the table, bismuth-based glass powder and refractory filler powder were mixed, and sample No. 1-10 were produced. Sample No. About 1-10, the thermal expansion coefficient, the glass transition point, the softening point, the laser sealing strength, the fluidity, and the airtightness after laser sealing were evaluated.

  The thermal expansion coefficient and the glass transition point were measured with a TMA apparatus. The thermal expansion coefficient was measured in a temperature range of 30 to 300 ° C. In addition, after each sample was sintered densely, what was processed into the predetermined shape was used as a measurement sample.

  The softening point was determined with a DTA apparatus. The measurement was performed in air, and the rate of temperature increase was 10 ° C./min.

  For fluidity, a powder having a mass corresponding to the synthesis density of each sample was dry-pressed into a button shape having an outer diameter of 20 mm using a mold and placed on a 40 mm × 40 mm × 2.8 mm thick high strain point glass substrate. Then, the temperature was increased in air at a rate of 10 ° C./min, held at the softening point of each sample + 30 ° C. for 10 minutes, and then cooled to room temperature at 10 ° C./min. It evaluated by measuring. Specifically, the case where the flow diameter was 20 mm or more was evaluated as “◯”, and the case where it was less than 20 mm was evaluated as “x”. The synthetic density is a theoretical density calculated by mixing the density of the glass powder and the density of the refractory filler powder at a predetermined volume ratio.

  The laser sealing strength was evaluated as follows. First, after each sample and vehicle (α-terpineol containing ethyl cellulose resin) were uniformly kneaded with a three-roll mill and made into a paste, an alkali-free glass substrate (OA-10 manufactured by Nippon Electric Glass Co., Ltd., 40 mm × 0) 0.5 mm thickness) on the edge of the non-alkali glass substrate and coated in a frame shape (30 μm thickness, 0.6 mm width) and dried in a drying oven at 125 ° C. for 10 minutes. Next, the temperature was raised from room temperature at 10 ° C./minute, and after baking for 10 minutes at a temperature of the softening point of each sample + 30 ° C., the temperature was lowered to room temperature at 10 ° C./minute to incinerate the resin components in the paste (debinding) Treatment) and fixing of the sealing material. Next, another alkali-free glass substrate (□ 40 mm × 0.5 mm thickness) is accurately stacked on the alkali-free glass substrate to which the sealing material is fixed, and then the alkali-free material having the fixed sealing material. By irradiating a laser beam having a wavelength of 808 nm along the sealing material from the glass substrate side, the sealing material was softened and fluidized, and the alkali-free glass substrates were hermetically sealed. In addition, the irradiation conditions (output, irradiation speed) of the laser beam were adjusted according to the average film thickness of the sealing material. Finally, both glass substrates after laser sealing are dropped onto the concrete from 1 m above, and “○” indicates that no peeling occurred at the laser-sealed portion, and “×” indicates that peeling occurred. evaluated.

  Airtightness after laser sealing was evaluated as follows. In the same manner as in the evaluation of the laser sealing strength, the sealing material was applied and fixed on an alkali-free glass substrate (□ 40 mm × 0.5 mm thickness). Subsequently, a metal Ca film (□ 20 mm, 300 nm thickness) is formed on another alkali-free glass substrate (□ 40 mm × 0.5 mm thickness) by vacuum deposition, and the humidity and oxygen concentration are controlled in a glove box. After the non-alkali glass substrate on which the sealing material is fixed and the non-alkali glass substrate on which the metal Ca film is formed are accurately stacked, the sealing material is applied to the sealing material from the non-alkali glass substrate side having the fixed sealing material. Then, the sealing material was softened and flowed by irradiating laser light having a wavelength of 808 nm, and the alkali-free glass substrates were hermetically sealed. In addition, the irradiation conditions (output, irradiation speed) of the laser beam were adjusted according to the average film thickness of the sealing material. The alkali-free glass substrate after laser sealing was held in a constant temperature and humidity chamber at 40 ° C.-90 RH% for 1500 hours. Thereafter, the case where the metallic Ca film maintained the metallic luster was evaluated as “◯”, and the case where it became transparent was evaluated as “X”. The metal Ca film becomes transparent calcium hydroxide when it reacts with moisture.

As apparent from Tables 1 and 2, Sample No. 1-8 have a glass transition point of 351-400 ° C., a softening point of 407-444 ° C., a thermal expansion coefficient α of 66-85 × 10 ⁻⁷ / ° C., fluidity, laser sealing strength and after laser sealing. The evaluation of airtightness was also good. On the other hand, sample No. Since Nos. 9 and 10 did not contain CuO + Fe ₂ O ₃ in the glass composition, the sealing material did not soften even when irradiated with laser light, and laser sealing could not be performed properly.

  The sealing material of the present invention is used for laser sealing of solar cells such as dye-sensitized solar cells and CIGS thin film compound solar cells in addition to laser sealing of organic EL devices such as organic EL displays and organic EL lighting devices. It is also suitable for laser sealing of MEMS packages.

Claims (13)

As a glass composition, in mass% in terms of _{oxide, Bi 2 O 3 70~90%,} B 2 O 3 2~12%, 1~15% ZnO, CuO + Fe 2 O 3 7.6 ~15%, CuO A bismuth-based glass containing 3 to 15%, MgO + CaO + SrO + BaO 0.1 to 20% , BaO 0.1 to 15% . Bismuth glass of claim 1 in which the content of Fe ₂ O ₃ is characterized in that 0.1 to 7 wt%. The bismuth-based glass according to claim 1 or 2, wherein the molar ratio BaO / ZnO has a value of 0.7-2 . The molar ratio _Bi 2 _O 3 _/ B 2 bismuth glass according to any one of claims 1 to 3, the value of _{O 3} is characterized in that it is a 1.6 to 2.3. The molar ratio _Bi 2 _O 3 / bismuth-based glass according to claim 1, the value of ZnO is equal to or not less than 1.55. The bismuth-based glass according to any one of claims 1 to 5, wherein the content of BaO is 0.9 mass% or more. The value of the molar ratio _{Bi 2 O 3 / B 2 O} 3 is 1.5 or less, and the molar ratio of BaO / ZnO value of claims 1～3,5,6, characterized in that at least 0.7 The bismuth-type glass in any one.   A sealing material comprising 55 to 100% by volume of a glass powder comprising the bismuth-based glass according to claim 1 and 0 to 45% by volume of a refractory filler powder.   The sealing material according to claim 8, wherein the refractory filler powder is one or more selected from cordierite, willemite, alumina, zirconium phosphate, zircon, zirconia, and tin oxide.   The sealing material according to claim 8 or 9, which does not substantially contain PbO.   The sealing material according to any one of claims 8 to 10, wherein a softening point is 500 ° C or lower.   It is used for the sealing process by a laser beam, The sealing material in any one of Claims 8-11 characterized by the above-mentioned.   The sealing material according to any one of claims 8 to 12, which is used for sealing an organic EL device or a solar cell.