JP2018062445A - Bismuth glass and sealing material prepared therewith - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a bismuth glass that has both softening fluidity and laser adsorption ability at high levels, and a sealing material prepared therewith.SOLUTION: A bismuth glass contains, as a glass composition, expressed in mass% based on the following oxides: BiOof 25 to 45%; BOof 20 to 35%; and CuO+MnO of 15 to 40%, with the molar ratio CuO/MnO of 0.5 to 6.2.SELECTED DRAWING: None

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. Conventionally, an organic resin adhesive having low-temperature curability has been used as an adhesive material for organic EL displays. However, organic resin adhesives cannot completely block the ingress of gas and moisture, so active elements with low water resistance and organic light emitting layers are likely to deteriorate, and the display characteristics of organic EL displays deteriorate over time. Has occurred.

  On the other hand, since the sealing material containing glass powder is hard to permeate | transmit gas and a water | moisture content compared with an organic resin adhesive, the airtightness inside an organic electroluminescent display can be ensured.

  However, since the glass powder has a softening temperature higher than that of the organic resin adhesive, there is a possibility that the active element and the organic light emitting layer are thermally deteriorated at the time of sealing. Under such circumstances, laser sealing has attracted attention. According to laser sealing, it is possible to locally heat only the part to be sealed, and seal an object to be sealed such as an alkali-free glass substrate without causing thermal degradation of the active element or the organic light emitting layer. can do.

  In recent years, it has been studied to maintain the characteristics of the hermetic package and to extend its life. For example, in an airtight package in which an LED element is mounted, a low-temperature fired substrate (LTCC) having aluminum nitride and a thermal via is used as a substrate from the viewpoint of thermal conductivity. In this case as well, the substrate and lid (lid) are used. ) Is preferably laser sealed. In particular, in an airtight package on which an LED element that emits light in the ultraviolet wavelength region is mounted, it becomes easy to maintain light emission characteristics in the ultraviolet wavelength region by laser sealing. Furthermore, thermal degradation of the LED element can be prevented by laser sealing. Further, even in an airtight package on which a MEMS (Micro Electric Mechanical System) element is mounted, laser sealing is preferable in order to prevent deterioration of the characteristics of the MEMS element.

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

  Sealing materials used for laser sealing generally include glass powder, refractory filler powder and laser absorber. The glass powder is a component that softens and flows during laser sealing, reacts with an object to be sealed, and ensures sealing strength. The refractory filler powder is a material that acts as an aggregate and reduces the coefficient of thermal expansion, and does not soften and flow during laser sealing. The laser absorbing material is a material for absorbing laser light at the time of laser sealing and converting it into thermal energy, and does not soften and flow at the time of laser sealing.

Conventionally, lead borate glass has been used as the glass powder, but in recent years, lead-free glass has been used from an environmental point of view. In particular, bismuth-based glass is promising as a lead-free glass because it has a low melting point and excellent softening fluidity. However, in the bismuth-based glass, the main component Bi ₂ O ₃ has almost no laser absorption capability, and thus the laser absorption capability tends to be insufficient. For this reason, in order to supplement the laser absorption capability of bismuth-based glass, the content of the laser absorber must be increased. However, if the content of the laser absorbing material increases, the laser absorbing material dissolves into the bismuth-based glass during laser sealing, thereby devitrifying the bismuth-based glass, and the desired softening fluidity cannot be secured. .

  Therefore, the present invention has been made in view of the above circumstances, and its technical problem is to create a bismuth-based glass that can achieve both softening fluidity and laser absorption capability at a high level and a sealing material using the same. That is.

As a result of intensive studies, the present inventors have found that the above technical problem can be solved by introducing predetermined amounts of CuO and MnO into bismuth-based glass, and propose the present invention. That is, the bismuth-based glass of the present invention contains, as a glass composition, mol% in terms of the following oxide, Bi ₂ O ₃ 25 to 45%, B ₂ O ₃ 20 to 35%, CuO + MnO 15 to 40%, The molar ratio CuO / MnO is 0.5 to 6.2. Here, “CuO + MnO” refers to the total amount of CuO and MnO. “CuO / MnO” refers to the value obtained by dividing the CuO content by the MnO content.

  The bismuth-based glass of the present invention contains 20 mol% or more of CuO and MnO in the total amount in the glass composition. CuO and MnO are components that greatly increase the laser absorption ability. Therefore, if the total amount of CuO and MnO is regulated to 20 mol% or more, the laser absorption ability can be remarkably enhanced. In particular, the ability to absorb laser light having a wavelength of 808 nm, which is widely used industrially, can be significantly increased.

According to the investigation by the present inventors, MnO-introduced raw materials such as MnO ₂ have an oxidizing action when melted. And when CuO and MnO are used together and the molar ratio CuO / MnO is regulated to 0.5 to 6.2 like the bismuth glass of the present invention, Cu ₂ O present in the glass at the time of melting is MnO. Oxidized by the introduced raw material, copper oxide having an oxidation number of 2 or more (for example, CuO) is increased, whereby the laser absorption ability in the near infrared wavelength region can be greatly enhanced.

  As described above, the bismuth-based glass of the present invention has a very high laser absorption capability because the total amount of CuO and MnO is 20 mol% or more and the molar ratio CuO / MnO is regulated to 0.5 to 6.2. When used as a sealing material, the amount of the laser absorbing material introduced can be reduced as much as possible. As a result, both softening fluidity and laser absorption ability can be achieved at a high level.

  Secondly, the bismuth-based glass of the present invention preferably further contains 1 to 20 mol% of ZnO in the glass composition.

  Third, the bismuth glass of the present invention preferably has a MnO content of 3 to 25 mol%.

  Fourth, it is preferable that the bismuth glass of the present invention does not substantially contain PbO. Here, “substantially does not contain PbO” refers to a case where the content of PbO in the glass composition is less than 0.1% by mass.

  Fifth, the sealing material of the present invention is a sealing material containing a glass powder made of bismuth-based glass and a refractory filler powder. The glass powder content is 50 to 95% by volume, and the refractory filler powder is contained. The amount is preferably 1 to 40% by volume, and the bismuth-based glass is preferably the bismuth-based glass.

  Sixth, in the sealing material of the present invention, the refractory filler powder is made of cordierite, willemite, alumina, zirconium phosphate compound, zircon, zirconia, tin oxide, quartz glass, β-eucryptite, spodumene. It is preferable that it is 1 type, or 2 or more types selected.

  Seventh, the sealing material of the present invention preferably has a laser absorber content of 5% by volume or less.

Eighth, the sealing material of the present invention is preferably used for laser sealing. In this way, thermal degradation of the element can be prevented during sealing. The light source of the laser beam used for laser sealing is not particularly limited, but 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. Further, the emission center wavelength of the laser beam is preferably 500 to 1600 nm, particularly preferably 750 to 1300 nm, in order for the sealing material to absorb the laser beam accurately.

The bismuth-based glass of the present invention contains, as a glass composition, mol%, Bi ₂ O ₃ 25 to 45%, B ₂ O ₃ 20 to 35%, CuO + MnO 15 to 40%, and a molar ratio CuO / MnO. It is 0.5-6.2. The reason for limiting the glass composition range of bismuth-based glass as described above is shown below. In addition, in description of a glass composition,% display points out mol%.

Bi ₂ O ₃ is a main component of bismuth-based glass and is a component that improves softening fluidity. The content of Bi ₂ O ₃ is 25 to 45%, preferably 30 to 42%, more preferably 35 to 40%. If the content of Bi ₂ O ₃ is too small, too high softening point, be irradiated with laser light, the glass is hardly softened flow. On the other hand, if the content of Bi ₂ O ₃ is too large, the thermal expansion coefficient becomes unreasonably high, and cracks are likely to occur in the material to be sealed and the sealing material layer during laser sealing, resulting in poor airtightness. Become. Further, the glass becomes thermally unstable, and the glass tends to be devitrified during laser sealing.

B ₂ O ₃ is a component that forms a glass network. The content of B ₂ O ₃ is 20 to 35%, preferably 22 to 32%, more preferably 24 to 30%. When the content of B ₂ O ₃ is too small, glass becomes thermally unstable, the glass is liable to devitrify during laser sealing. On the other hand, if the content of B ₂ O ₃ is too large, the softening point becomes too high, and the glass becomes difficult to soften and flow even when irradiated with laser light.

  CuO and MnO are components that greatly increase the laser absorption ability. The total amount of CuO and MnO is 20 to 40%, preferably 22 to 35%, and more preferably 25 to 30%. When the total amount of CuO and MnO is too small, the laser absorption ability tends to be lowered. On the other hand, if the total amount of CuO and MnO is too large, the softening point becomes too high, and the glass becomes difficult to soften and flow even when irradiated with laser light. Further, the glass becomes thermally unstable, and the glass tends to be devitrified during laser sealing. In addition, the content of CuO is preferably 8 to 30%, more preferably 13 to 25%. The content of MnO is preferably 3 to 25%, more preferably 5 to 15%.

MnO-introduced raw materials such as MnO ₂ have an oxidizing action when melted. In the bismuth-based glass, when CuO and MnO are used in combination and the molar ratio CuO / MnO is regulated to 0.5 to 6.2, Cu ₂ O present in the glass at the time of melting is oxidized by the MnO introduced raw material. As a result, the number of copper oxides having an oxidation number of 2 or more increases, and thereby the laser absorption ability in the near infrared wavelength region can be greatly enhanced. The molar ratio CuO / MnO is 0.5 to 6.2, preferably 0.7 to 6.0, and more preferably 1.0 to 3.5. If the molar ratio CuO / MnO is too small, the glass becomes thermally unstable, and the glass tends to devitrify during laser sealing. On the other hand, if the molar ratio CuO / MnO is too large, Cu ₂ O is not sufficiently oxidized at the time of melting, and it becomes difficult to obtain a desired laser absorption ability.

ZnO is a component that decreases the thermal expansion coefficient. The content of ZnO is preferably 0 to 25%, more preferably 1 to 20%, still more preferably 5 to 15%. When there is too little content of ZnO, a thermal expansion coefficient will become high easily. On the other hand, when the content of ZnO is too large, when the content of Bi ₂ O ₃ is 35% or more, the glass becomes thermally unstable, and the glass is easily devitrified at the time of laser sealing.

  In addition to the above components, for example, the following components may be added.

Fe ₂ O ₃ is a component that enhances the laser absorption ability, and is a component that suppresses devitrification during laser sealing when the content of Bi ₂ O ₃ is 35% or more. The content of Fe ₂ O ₃ is preferably 0 to 5%, 0.1 to 3%, particularly 0.2 to 2%. When the content of Fe ₂ O ₃ is too large, is impaired balance of components in the glass composition, the glass is liable to devitrify reversed.

Al ₂ O ₃ is a component that improves water resistance. The content is preferably 0 to 5%, 0 to 3%, particularly preferably 0.1 to 2%. When the content of Al ₂ O ₃ is too large, too high softening point, be irradiated with laser light, the glass is hardly softened flow.

  MgO, CaO, SrO and BaO are components that enhance the thermal stability. However, if the content of MgO, CaO, SrO and BaO is too large, it becomes difficult to lower the thermal expansion coefficient while ensuring softening fluidity. Therefore, the total amount and individual content of MgO, CaO, SrO and BaO are preferably 0-7%, 0-5%, 0-3%, 0-2%, 0-1%, especially 0-1. %.

SiO ₂ is a component that improves water resistance. The content is preferably 0 to 10%, 0 to 5%, particularly preferably 0 to less than 1%. When the content of SiO ₂ is too large, the softening point becomes too high, and the glass is softened and hardly flows even when irradiated with laser light.

Li ₂ O, Na ₂ O, K ₂ O, and Cs ₂ O are components that lower the softening point, but have an action of promoting devitrification at the time of melting. Therefore, the total content of these components is preferably 2% or less, particularly preferably less than 1%.

P ₂ O ₅ is a component that suppresses devitrification at the time of melting. However, if the amount of P ₂ O ₅ added is too large, the glass tends to undergo phase separation at the time of melting. Therefore, the content of P ₂ O ₅ is preferably 0 to 5%, particularly preferably less than 0 to 1%.

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 contents of La ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O ₃ are too large, The softening point becomes too high, and the glass becomes difficult to soften even when irradiated with laser light. Therefore, the contents of La ₂ O ₃ , Y ₂ O ₃ and Gd ₂ O ₃ are each preferably 0 to 5%, particularly preferably 0 to less than 1%.

TiO ₂ , V ₂ O ₅ , Cr ₂ O ₃ , Co ₂ O ₃ , MoO ₃ , NiO and CeO ₂ are components that enhance the laser absorption ability. The content of each component is preferably 0-7%, 0-4%, especially 0-1%. When there is too much content of each component, it will become easy to devitrify glass at the time of laser sealing.

  It is preferable that PbO is not substantially contained from an environmental viewpoint.

  The sealing material of the present invention is a sealing material containing a glass powder made of bismuth-based glass and a refractory filler powder. The glass powder content is 50 to 95% by volume, and the refractory filler powder content is 1 to 1. It is preferably 40% by volume and the bismuth glass is the above bismuth glass.

  In the sealing material of the present invention, the glass powder content is preferably 50 to 95% by volume, 60 to 80% by volume, and particularly preferably 65 to 75% by volume. When there is little content of glass powder, the softening fluidity | liquidity of a sealing material will fall easily. On the other hand, when the content of the glass powder is large, the content of the refractory filler powder is relatively decreased, and the thermal expansion coefficient of the sealing material may be unduly increased.

The maximum particle diameter _Dmax of the glass powder is preferably 10 μm or less, particularly 5 μm or less. When the maximum particle diameter _Dmax of the glass powder is too large, the time required for laser sealing becomes long, and it becomes difficult to make the gap between the objects to be sealed uniform, and the accuracy of laser sealing tends to decrease. 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%.

  The softening point of the glass powder is preferably 480 ° C. or lower, 450 ° C. or lower, particularly preferably 350 to 430 ° C. If the softening point of the glass powder is too high, the glass becomes difficult to soften during laser sealing, so that the sealing strength cannot be increased unless the output of the laser beam is increased. Here, the “softening point” refers to the temperature at the fourth inflection point when measured by macro-type differential thermal analysis.

  The glass powder is prepared by, for example, preparing a glass batch in which various raw materials are prepared, putting it in platinum melting and melting it at 900 to 1200 ° C. for 1 to 3 hours, and then pouring the molten glass between water-cooled twin rollers to form a film. It is produced by pulverizing the obtained glass film with a ball mill and performing classification such as air classification.

  It is preferable to use one or more of nitrates, sulfates, dioxides, and peroxide salts as a part of the raw materials used for producing the glass powder. Among the coloring components, there is a component (particularly CuO) that increases the laser absorption ability when the oxidation number is high. And if such a raw material is used, the oxidation number of the coloring component in a molten glass can be made high.

  In the sealing material of the present invention, the content of the refractory filler powder is preferably 1 to 40% by volume, 10 to 45% by volume, 20 to 40% by volume, particularly 22 to 35% by volume. If the content of the refractory filler powder is small, the thermal expansion coefficient of the sealing material may be unduly high. On the other hand, when the content of the refractory filler powder is large, the content of the glass powder is relatively small, and the softening fluidity of the sealing material is likely to be lowered.

  Various materials can be used as the refractory filler powder. Among them, cordierite, willemite, alumina, zirconium phosphate compounds, zircon, zirconia, tin oxide, quartz glass, β-eucryptite, spodumene. 1 type or 2 types or more chosen from are preferable. These refractory filler powders have a low thermal expansion coefficient, a high mechanical strength, and a good compatibility with the bismuth glass of the present invention. Β-eucryptite is particularly preferable because it has a high effect of reducing the thermal expansion coefficient of the sealing material.

The maximum particle diameter _Dmax of the refractory filler powder is preferably 15 μm or less, less than 10 μm, less than 5 μm, and particularly less than 0.5 to 3 μm. If the maximum particle diameter _Dmax of the refractory filler powder is too large, it becomes difficult to make the gap between the objects to be sealed uniform, and it becomes difficult to narrow the gap between the objects to be sealed, thereby reducing the thickness of the organic EL display and hermetic package. It becomes difficult to plan. Note that when the gap between the objects to be sealed is large and the difference in thermal expansion coefficient between the objects to be sealed and the sealing material layer is large, cracks or the like are likely to occur in the objects to be sealed or the sealing material layer.

  In the sealing material of the present invention, the content of the laser absorber is preferably 0 to 5% by volume, 0 to 3% by volume, 0 to 1% by volume, particularly 0 to 0.1% by volume. When there is too much content of a laser absorber, a laser absorber will melt in glass at the time of laser sealing, and this will devitrify glass, and it will become easy to fall the softening fluidity of a sealing material.

  In the sealing material of the present invention, the light absorptance of monochromatic light having a wavelength of 808 nm is preferably 75% or more, and more preferably 80% or more. If this light absorptance is low, the sealing material layer cannot absorb light properly at the time of laser sealing, and the sealing strength cannot be increased unless the output of the laser light is increased. If the output of the laser beam is increased, the element may be thermally deteriorated during laser sealing. Here, “light absorptivity in monochromatic light with a wavelength of 808 nm” is obtained by measuring the reflectance and transmittance of monochromatic light at λ = 808 nm with a spectrophotometer for the sealing material layer fired to a film thickness of 5 μm. This corresponds to a value obtained by subtracting the total value of 100% from 100%.

In the sealing material of the present invention, the thermal expansion coefficient is preferably 75 × 10 ⁻⁷ / ° C. or less, particularly 50 × 10 ⁻⁷ / ° C. or more and 71 × 10 ⁻⁷ / ° C. or less. In this way, when the material to be sealed has a low expansion, the stress remaining in the material to be sealed or the sealing material layer is reduced, so that cracks are hardly generated in the material to be sealed or the sealing material layer. 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 510 ° C. or lower, 480 ° C. or lower, particularly 350 to 450 ° C. If the softening point of the sealing material is too high, the sealing material layer becomes difficult to soften and flow at the time of laser sealing, so that the sealing strength cannot be increased unless the output of the laser beam is increased.

  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 sealing material 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 sealing material paste. Moreover, surfactant, a thickener, etc. can also be added as needed. The sealing material paste is applied to an object to be sealed using an applicator such as a dispenser or a screen printer, and then subjected to a binder removal step.

  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.

  The present invention will be described in detail based on examples. The following examples are merely illustrative. The present invention is not limited to the following examples.

  Tables 1 and 2 show examples of the present invention (sample Nos. 1 to 6) and comparative examples (samples No. 7 to 11).

The glass powder described in the table was produced as follows. First, a glass batch in which various raw materials 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 ° C. for 1 hour. During melting, the molten glass was homogenized by stirring with a platinum rod. Next, a part of the obtained molten glass was poured out between water-cooled twin rollers and formed into a film shape, and the remaining molten glass was poured out into a carbon mold and formed into a rod shape. Finally, after grinding the resulting glass film with a ball mill, the average particle diameter _{D 50} of 1.0 .mu.m, a maximum particle diameter _{D max} is then classified by an air classifier so as to 4.0 .mu.m. Further, the rod-shaped glass was put into an electric furnace maintained at a temperature about 20 ° C. higher than the annealing point, and then slowly cooled to room temperature at a temperature lowering rate of 3 minutes / minute.

Β-eucryptite was used as the refractory filler powder. The refractory filler powder is adjusted to an average particle diameter D _{50 of} 1.0 μm and a maximum particle diameter D _{max of} 3.0 μm by air classification.

  Glass powder and refractory filler powder were mixed at the mixing ratio shown in the table. 1 to 11 were produced. Sample No. About 1-11, a thermal expansion coefficient, a light absorptivity, softening fluidity | liquidity, sealing strength, and airtightness were evaluated. “N / A” in the table means that evaluation is not possible.

  A thermal expansion coefficient is the value measured in the temperature range of 30-300 degreeC with the TMA apparatus. In addition, as a measurement sample of TMA, after each sample was sintered precisely, it was processed into a predetermined shape.

  The light absorption rate was measured as follows. First, each sample and vehicle (tripropylene glycol monobutyl ether containing ethyl cellulose resin) were uniformly kneaded with a three-roll mill and made into a paste, and then an alkali-free glass substrate (OA-10 manufactured by Nippon Electric Glass Co., Ltd., 40 mm × (40 mm × 0.5 mm thickness) on a 30 mm × 30 mm square and dried in a drying oven at 120 ° C. for 10 minutes. Next, the temperature was raised from room temperature at 10 ° C./minute, baked at 510 ° C. for 10 minutes, then cooled to room temperature at 10 ° C./minute, and fixed on the glass substrate. Subsequently, with respect to the obtained fired film having a thickness of 5 μm, the reflectance and transmittance of monochromatic light having a wavelength λ = 808 nm were measured with a spectrophotometer, and a value obtained by subtracting the total value from 100% was absorbed. Rate.

For softening fluidity, for each sample, a powder having a mass corresponding to 0.6 cm ³ minutes was dry-pressed into a button shape having an outer diameter of 20 mm using a mold, and this was placed on an alumina substrate having a thickness of 25 mm × 25 mm × 0.6 mm. After being placed and heated in air at a rate of 10 ° C / min, held at 510 ° C for 10 minutes, then cooled to room temperature at 10 ° C / min, and evaluated by measuring the diameter of the resulting button It is a thing. Specifically, the case where the flow diameter was 16.0 mm or more was evaluated as “◯”, and the case where it was less than 16.0 mm was evaluated as “x”.

The sealing strength was evaluated as follows. First, after each sample and vehicle (tripropylene glycol monobutyl ether containing ethyl cellulose resin) were uniformly kneaded with a three-roll mill and formed into a paste, an alkali-free glass substrate (OA-10, □ manufactured by Nippon Electric Glass Co., Ltd.) 40 mm × 0.5 mm thickness, thermal expansion coefficient 38 × 10 ⁻⁷ / ° C.) along the edge of the non-alkali glass substrate in a frame shape (5 μm thickness, 0.6 mm width). Dry at 10 ° C. for 10 minutes. Next, the temperature is raised from room temperature at 10 ° C./minute, baked at 510 ° C. for 10 minutes, and then lowered to room temperature at 10 ° C./minute, incineration of the resin component in the paste (debinding treatment) and sealing material Fixing was performed to form a sealing material layer on the alkali-free glass substrate. Next, another alkali-free glass substrate (□ 40 mm × 0.5 mm thickness) in which no sealing material layer is formed is accurately stacked on the alkali-free glass substrate having the sealing material layer, and then sealed. By irradiating a laser beam having a wavelength of 808 nm along the sealing material layer from the alkali-free glass substrate side having the material layer, the sealing material layer was softened and flowed, and the alkali-free glass substrates were hermetically sealed. . The laser light irradiation conditions (output and irradiation speed) were adjusted according to the average thickness of the sealing material layer. Finally, after the obtained sealing structure was dropped onto the concrete from 1 m above, “○” indicates that no peeling occurred at the interface between the alkali-free glass and the sealing material layer, The sealing strength was evaluated with “Δ” indicating that the interface of the adhesive material layer was partially peeled, and “x” indicating that the interface between the alkali-free glass and the sealing material layer was completely peeled.

  Airtightness was evaluated as follows. The sealing structure obtained by the above method was held for 24 hours in a constant temperature and humidity chamber maintained at 121 ° C., 100% humidity and 2 atm. After that, the sealing structure was observed with an optical microscope. The sealing material layer did not change in quality and the invasion of moisture was not recognized in the sealing structure. The airtightness was evaluated with “Δ” indicating that the sealing material layer was altered and “X” indicating that water had entered the sealing structure.

As can be seen from Table 1, sample no. In Nos. 1 to 6, since the glass composition of the glass powder was regulated within a predetermined range, the evaluation of thermal expansion coefficient, light absorption rate, softening fluidity, sealing strength, and airtightness was good. On the other hand, sample No. Since No. 7 had a large molar ratio CuO / MnO, the light absorptance was low, and the evaluation of sealing strength and airtightness was slightly inferior. Sample No. In No. 8, since the molar ratio CuO / MnO was small, devitrification occurred at the time of firing and laser sealing, and due to this devitrification, evaluation of softening fluidity, sealing strength, and airtightness was poor. Sample No. No. 9 had a low light absorptivity because the total amount of CuO and MnO was small, and the evaluation of sealing strength and airtightness was poor. Sample No. In No. 10, since the total amount of CuO and MnO was large, sintering of the sealing material layer was insufficient, and all evaluations were impossible. Sample No. Since No. 11 had a large content of Bi ₂ O ₃ , all evaluations were impossible due to devitrification.

  The bismuth glass of the present invention and the sealing material using the glass are dye-sensitized solar cells, 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 solar cells such as, laser sealing of airtight packages such as MEMS packages and LED packages.

Claims (8)

As a glass composition, in mol% terms of _{oxide, Bi 2 O 3 25~45%,} B 2 O 3 20~35%, containing 15 to 40% CuO + MnO, is and the molar ratio CuO / MnO 0.5 Bismuth-type glass characterized by being -6.2.   Furthermore, 1-20 mol% of ZnO is contained in a glass composition, The bismuth-type glass of Claim 1 characterized by the above-mentioned.   Content of MnO is 3-25 mol%, The bismuth-type glass of Claim 1 or 2 characterized by the above-mentioned.   The bismuth-based glass according to any one of claims 1 to 3, which does not substantially contain PbO. In a sealing material containing a glass powder made of bismuth-based glass and a refractory filler powder,
The glass powder content is 50 to 95% by volume, the refractory filler powder content is 1 to 40% by volume, and the bismuth glass is the bismuth glass according to any one of claims 1 to 4. A sealing material characterized by that.   The refractory filler powder is one or more selected from cordierite, willemite, alumina, zirconium phosphate compounds, zircon, zirconia, tin oxide, quartz glass, β-eucryptite, and spodumene. The sealing material according to claim 5.   The sealing material according to claim 5 or 6, wherein the content of the laser absorbing material is 5% by volume or less.   The sealing material according to claim 5, wherein the sealing material is used for laser sealing.