JP2013006720A - Sealing material paste, and sealing material layer-attached glass substrate using the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To heighten long-term reliability of an organic EL device including an organic EL element package or the like by inventing a sealing material paste and a sealing material layer-attached glass substrate which can be laser-sealed properly by a low-output laser.SOLUTION: In this sealing material paste, namely, in a sealing material paste containing inorganic powder and a vehicle, the inorganic powder contains SnO-containing glass powder, and the vehicle contains a resin binder and a solvent, and the value of inorganic powder/vehicle is 0.45-1.65 in terms of the mass ratio.

Description

  The present invention relates to a sealing material paste and a glass substrate with a sealing material layer using the same, and specifically, a sealing material paste suitable for laser sealing (hereinafter referred to as laser sealing) and the same. The present invention relates to a glass substrate with a sealing material layer.

  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 does not depend on the viewing angle, is bright because of 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 is a problem that the display characteristics of the display deteriorate 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 a sealing material containing glass powder, 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. It was necessary to soften and flow. 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.

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

  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 while preventing thermal degradation of the active element or the like.

  Patent Documents 1 and 2 describe laser sealing of glass substrates of a field emission display. However, Patent Documents 1 and 2 do not describe a specific material configuration, particularly a material configuration of the sealing material paste, and it is unclear what material configuration is suitable for laser sealing. If the output of the laser is increased, laser sealing can be performed without optimizing the material configuration. In this case, however, the active element or the like may be heated to deteriorate the display characteristics of the organic EL display. .

  Therefore, the present invention creates a sealing material paste and a glass substrate with a sealing material layer that can be properly laser-sealed with a low-power laser, thereby enabling long-term use of an organic EL device including an organic EL element package. Increasing reliability is a technical issue.

  As a result of intensive studies, the present inventors have adopted the inorganic powder containing SnO-containing glass powder as the sealing material and solved the above technical problem by strictly regulating the content ratio of the inorganic powder and the vehicle. The present invention is found and proposed as the present invention. That is, the sealing material paste of the present invention is a sealing material paste including an inorganic powder and a vehicle. The inorganic powder includes a SnO-containing glass powder, the vehicle includes a resin binder and a solvent, and the inorganic powder / vehicle has a mass ratio. The value is 0.45 to 1.65. Here, the “SnO-containing glass powder” refers to a glass powder containing 20 mol% or more of SnO as a glass composition.

  The inorganic powder according to the present invention includes at least a SnO-containing glass powder. SnO-containing glass powder has a low softening temperature and can soften and flow at low temperatures. For this reason, the efficiency and reliability of laser sealing can be improved.

  Moreover, when apply | coating sealing material paste on a glass substrate, a screen printing method is normally used. The inventors of the present invention have found that when a sealing material layer formed by applying a sealing material paste and then firing is adhered to an object to be sealed such as a glass substrate, laser sealing can be performed with a low-power laser. That is, in order to increase the efficiency and reliability of laser sealing, it is important to increase the surface smoothness of the sealing material layer. As a result of intensive studies, the present inventors have found that the printability of the sealing material paste has a great influence on the surface state of the sealing material layer.

  Therefore, by adjusting the value of the inorganic powder / vehicle by mass ratio to 0.5 to 1.5, the surface smoothness of the sealing material layer is improved, and the adhesion between the sealing material layer and the glass substrate is remarkable. It is possible to improve the laser sealing with a low-power laser. As a result, it is possible to appropriately ensure the airtightness inside the organic EL device while preventing thermal deterioration of the organic EL element.

  Secondly, in the sealing material paste of the present invention, the vehicle preferably contains a plurality of resin binders having different molecular weights.

  Thirdly, in the sealing material paste of the present invention, the resin binder is preferably an aliphatic polyolefin carbonate and the number average molecular weight thereof is preferably 50,000 to 500,000.

  Fourthly, the sealing material paste of the present invention further comprises N, N′-dimethylformamide, ethylene glycol, dimethyl sulfoxide, dimethyl carbonate, propylene carbonate, butyrolactone, caprolactone, N-methyl-2- It is preferable to include one or more selected from pyrrolidone, phenyl diglycol (PhDG), dibutyl phthalate (DBP), benzyl glycol (BzG), benzyl diglycol (BzDG), and phenyl glycol (PhG).

Fifth, in the sealing material paste of the present invention, the SnO-containing glass powder contains, as a glass composition, mol%, SnO 35 to 70%, P ₂ O ₅ 10 to 30%, and its maximum particle size. It is preferable that _D99 is 10 μm or less. Here, the “maximum particle size D ₉₉ ” refers to a value measured by a laser diffraction particle size distribution meter, and in the volume-based cumulative particle size distribution curve measured by the laser diffraction particle size distribution meter, the accumulated amount is a particle size. The particle size is 99% cumulative from the smaller of the two.

Sixth, the sealing material paste of the present invention, the inorganic powder further comprises a refractory filler, and it is preferable that the maximum particle diameter D ₉₉ is 5μm or less. Since the refractory filler has a low thermal expansion coefficient, it is possible to reduce the thermal expansion coefficient of the sealing material layer.

  Seventhly, in the sealing material paste of the present invention, the inorganic powder preferably further contains a pigment. Since the pigment is excellent in color developability, the laser absorbability is good.

Eighth, in the sealing material paste of the present invention, the pigment is preferably amorphous carbon or graphite, and the average particle diameter D _{50 of the} primary particles is preferably 1 to 100 nm. Here, the “average particle diameter D ₅₀ ” refers to a value measured with a laser diffraction particle size distribution meter, and in the cumulative particle size distribution curve based on volume when measured with a laser diffraction particle size distribution meter, the integrated amount is the particle size. The particle diameter is 50% cumulative from the smaller of the two.

  Ninthly, the sealing material paste of the present invention is preferably used for sealing an organic EL device. Here, the “organic EL device” includes an organic EL display, organic EL lighting, and the like.

Tenth, the sealing material paste of the present invention is preferably subjected to a binder removal treatment in an inert atmosphere. Here, the “inert atmosphere” includes a neutral gas atmosphere such as an N ₂ gas atmosphere and an Ar gas atmosphere, and a reduced pressure atmosphere such as a vacuum atmosphere.

Eleventh, the sealing material paste of the present invention is preferably used for laser sealing, particularly laser sealing in an inert atmosphere. As described above, when laser sealing is performed, only the portion to be sealed can be locally heated, so that the glass substrates can be sealed together while preventing thermal degradation of the active element or the like. Various lasers can be used for laser sealing. In particular, 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.

  Twelfth, the glass substrate with a sealing material layer of the present invention is a glass substrate with a sealing material layer formed by applying a sealing material paste to a glass substrate and then firing the glass substrate. It is a material paste, and the sealing material layer has an average thickness of 8 μm or less. Here, “average thickness of the sealing material layer” refers to a value measured by a non-contact type laser film thickness meter.

  Thirteenthly, the glass substrate with a sealing material layer of the present invention preferably has a surface roughness (Ra) of the sealing material layer of 1.1 μm or less. Here, “surface roughness (Ra)” is a value measured with a surface roughness meter.

  Fourteenth, the glass substrate with a sealing material layer of the present invention preferably has a surface roughness (RMS) of the sealing material layer of 1.7 μm or less. Here, “surface roughness (RMS)” is a value measured with a surface roughness meter.

  15thly, as for the glass substrate with a sealing material layer of this invention, the average thickness of a sealing material layer is 2.2-8 micrometers, and the surface roughness (Ra) of a sealing material layer is 1.1 micrometers or less. It is characterized by being.

  Sixteenth, in the glass substrate with a sealing material layer of the present invention, the average thickness of the sealing material layer is 2.2 to 8 μm, and the surface roughness (RMS) of the sealing material layer is 1.7 μm or less. It is characterized by being.

It is a schematic diagram which shows the softening temperature Ts of the inorganic powder when measured with a macro type DTA apparatus.

  In the sealing material paste of the present invention, the value of the inorganic powder / vehicle by mass ratio is preferably 0.45 to 1.65, particularly preferably 0.5 to 1.5. When the value of the inorganic powder / vehicle is less than 0.45, the viscosity of the sealing material paste becomes too low, and bleeding occurs during the coating operation such as screen printing, and the film thickness of the coating film is the target value. Bigger than. In particular, when the coating film is formed in a frame shape, the tendency becomes remarkable at the corner. Further, when the value of the inorganic powder / vehicle is less than 0.45, when the sealing material paste is transferred to the glass substrate, the separation of the plate is deteriorated, so that the surface roughness of the sealing material layer is increased. On the other hand, when the value of the inorganic powder / vehicle is larger than 1.5, the viscosity of the sealing material paste becomes too high, and the coating film thickness varies greatly during coating operations such as screen printing. Since the leveling property of the film is also lowered, the surface roughness of the sealing material layer is increased. Therefore, when the value of the inorganic powder / vehicle is out of the above range, it becomes difficult to uniformly adhere the sealing material layer and the glass substrate before laser sealing, so laser sealing is performed with a low-power laser. It becomes difficult.

  In the sealing material paste of the present invention, the vehicle preferably includes a plurality of resin binders having different molecular weights, and the resin binder is more preferably the same type of resin binder. When reducing the average thickness of the sealing material layer, it is necessary to reduce the content of the inorganic powder in the sealing material paste. However, when the content of the inorganic powder is reduced, the viscosity of the sealing material paste is lowered, and the printability is easily lowered. As a result, the surface roughness of the sealing material layer increases, and it becomes difficult to perform laser sealing at a low output. Therefore, when multiple resin binders with different molecular weights are used, especially when a high molecular weight resin binder is used in combination, the viscosity of the sealing material paste is adjusted even if the content of the inorganic powder in the sealing material paste is reduced. It becomes easy. Further, when a plurality of resin binders of the same kind are used, it becomes easier to adjust the viscosity of the sealing material paste.

  In the sealing material paste of the present invention, the resin binder is preferably an aliphatic polyolefin carbonate, particularly polyethylene carbonate or polypropylene carbonate. These resin binders have the characteristic that it is difficult to alter the SnO-containing glass powder during binder removal or laser sealing. Moreover, those number average molecular weights are 50000-500000, Especially 80000-300000 are preferable. If it does in this way, it will become easy to optimize the viscosity of sealing material paste.

  In the sealing material paste of the present invention, N, N′-dimethylformamide, ethylene glycol, dimethyl sulfoxide, dimethyl carbonate, propylene carbonate, butyrolactone, caprolactone, N-methyl-2-pyrrolidone, phenyl diglycol ( It is preferable to include one or more selected from PhDG), dibutyl phthalate (DBP), benzyl glycol (BzG), benzyl diglycol (BzDG), and phenyl glycol (PhG). These solvents have the characteristic that it is difficult to alter the SnO-containing glass powder during binder removal or laser sealing. In particular, among these solvents, one or two selected from propylene carbonate, phenyl diglycol (PhDG), dibutyl phthalate (DBP), benzyl glycol (BzG), benzyl diglycol (BzDG), and phenyl glycol (PhG). The above is preferable. The boiling point of these solvents is 240 ° C. or higher. For this reason, when these solvents are used, it becomes easy to suppress the volatilization of the solvent during application work such as screen printing, and as a result, the sealing material paste can be used stably for a long period of time. . Furthermore, phenyl diglycol (PhDG), dibutyl phthalate (DBP), benzyl glycol (BzG), benzyl diglycol (BzDG), and phenyl glycol (PhG) have high affinity with pigments. For this reason, even if the addition amount of these solvents is small, the situation where a pigment separates in the sealing material paste can be suppressed.

SnO-containing glass powder, as a glass composition, in mol%, SnO 35 to _70%, preferably contains _P 2 O 5 _10~30%. The reason for limiting the glass composition range as described above will be described below. In addition, in description of the content range of each component,% display points out mol% except the case where there is particular notice.

  SnO is a component that lowers the melting point of glass, and its content is preferably 35 to 70%, 40 to 70%, and particularly preferably 50 to 68%. If the SnO content is 50% or more, the glass powder is softened and flowed easily during laser sealing. When the content of SnO is less than 35%, the viscosity of the glass becomes too high, and it becomes difficult to perform laser sealing with a desired laser output. On the other hand, if the SnO content is more than 70%, vitrification becomes difficult.

P ₂ O ₅ is a glass-forming oxide and is a component that increases the thermal stability of glass. The content is preferably 10 to 30%, 15 to 27%, particularly preferably 15 to 25%. When the content of P ₂ O ₅ is less than 10%, the thermal stability of the glass tends to be lowered. On the other hand, when the content of P ₂ O ₅ is more than 30%, reduces the weather resistance of the glass, it becomes difficult to ensure long-term reliability of the organic EL device or the like.

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

  ZnO is an intermediate oxide and a component that stabilizes the glass. The content is preferably 0 to 30%, 1 to 20%, particularly preferably 1 to 15%. When there is more content of ZnO than 30%, the thermal stability of glass will fall easily.

B ₂ O ₃ is a glass-forming oxide, a component that stabilizes the glass, and a component that enhances the weather resistance of the glass. The content is preferably 0 to 20%, 1 to 20%, particularly preferably 2 to 15%. If the content of B ₂ O ₃ is more than 20%, the viscosity of the glass becomes too high, and it becomes difficult to perform laser sealing with a desired laser output.

Al ₂ O ₃ is an intermediate oxide, a component that stabilizes the glass, and a component that lowers the thermal expansion coefficient of the glass. The content is preferably 0 to 10%, 0.1 to 10%, particularly preferably 0.5 to 5%. When the content of Al ₂ O ₃ is more than 10%, the softening temperature of the glass powder is unduly increased, and it becomes difficult to perform laser sealing with a desired laser output.

SiO ₂ is a glass-forming oxide and is a component that stabilizes the glass. The content is preferably 0 to 15%, particularly preferably 0 to 5%. When the content of SiO ₂ is more than 15%, the softening temperature of the glass powder rises unreasonably and it becomes difficult to perform laser sealing with a desired laser output.

Li ₂ O is a component that lowers the melting point of glass, and its content is preferably 0 to 5%. The content of Li 2 _O is more than 5%, the thermal stability of the glass tends to decrease. Na ₂ O is a component that lowers the melting point of glass, and its content is preferably 0 to 10%, particularly preferably 0 to 5%. When the content of Na 2 _O is greater than 10%, thermal stability of the glass tends to decrease. K ₂ O is a component that lowers the melting point of glass, and its content is preferably 0 to 5%. When the content of K 2 _O is more than 5%, the thermal stability of the glass tends to decrease.

MgO + Ta ₂ O ₅ + MoO ₃ + WO ₃ is a component that increases the thermal stability of the glass, and its content is preferably 0 to 10%, particularly preferably 0 to 5%. If the content of MgO + Ta ₂ O ₅ + MoO ₃ + WO ₃ is more than 10%, the softening temperature of the glass powder rises unreasonably, making it difficult to perform laser sealing with a desired laser output. The contents of MgO, Ta ₂ O ₅ , MoO ₃ , and WO ₃ are each preferably 0 to 5%. Here, “MgO + Ta ₂ O ₅ + MoO ₃ + WO ₃ ” refers to the total amount of MgO, Ta ₂ O ₅ , MoO ₃ , and WO ₃ .

  BaO is a component that enhances the thermal stability of the glass, and its content is preferably 0 to 10%. When there is more content of BaO than 10%, the component balance of a glass composition will be impaired and it will become easy to devitrify glass conversely.

La ₂ O ₃ is a component that enhances the thermal stability of the glass and is a component that enhances the weather resistance of the glass. The content is preferably 0 to 15%, 0 to 10%, particularly preferably 0 to 5%. When the content of La ₂ O ₃ is more than 15%, batch cost soars.

In ₂ O ₃ is a component that enhances the thermal stability of the glass, and its content is preferably 0 to 5%. When the content of In ₂ O ₃ is more than 5%, the batch cost increases.

F ₂ is a component to lower the melting point of the glass, the content thereof is preferably 0 to 5%. When the content of F ₂ is greater than 5%, the thermal stability of the glass tends to decrease.

  In addition to the above components, other components (CaO, SrO, etc.) can be added, for example, up to 10%.

  It is preferable that SnO containing glass powder does not contain PbO substantially from an environmental viewpoint. Here, “substantially no PbO” refers to the case where the content of PbO in the glass composition is 1000 ppm (mass) or less.

  It is preferable that SnO containing glass powder does not contain a transition metal oxide substantially. If it does in this way, it will become difficult to reduce the thermal stability of glass. Here, “substantially no transition metal oxide” refers to the case where the content of the transition metal oxide in the glass composition is 3000 ppm (mass) or less, preferably 1000 ppm (mass) or less.

In the sealing material paste of the present invention, the maximum particle diameter D ₉₉ of the SnO-containing glass powder is preferably 10 μm or less, particularly preferably 7 μm or less. If it does in this way, the softening temperature of the outermost surface of an application layer can fall, and the softening fluidity | liquidity of an application layer can be improved. As a result, the surface smoothness of the sealing material layer is improved, the time required for laser sealing is shortened, and even if the difference in thermal expansion coefficient between the sealing material layer and the glass substrate is large, the sealing portion or glass Cracks are less likely to occur on the substrate.

The inorganic powder according to the present invention preferably further contains a refractory filler. In this way, the thermal expansion coefficient and mechanical strength of the sealing material layer can be increased. Zircon, zirconia, tin oxide, quartz, β-spodumene, cordierite, mullite, quartz glass, β-eucryptite, β-quartz, zirconium phosphate, zirconium phosphate tungstate, zirconium tungstate as refractory filler NbZr (PO ₄ ) _{3 and} other compounds having a basic structure of [AB ₂ (MO ₄ ) ₃ ],
A: Li, Na, K, Mg, Ca, Sr, Ba, Zn, Cu, Ni, Mn etc. B: Zr, Ti, Sn, Nb, Al, Sc, Y etc. M: P, Si, W, Mo etc. Alternatively, these solid solutions can be used, but zirconium phosphate, zirconium tungstate phosphate, and NbZr (PO ₄ ) ₃ are particularly preferable because they have a large effect of reducing the thermal expansion coefficient.

Maximum particle diameter _{D 99} of the refractory filler is 5μm or less, in particular 3μm or less. If it does in this way, the surface smoothness of a sealing material layer can be improved. In particular, when the average thickness of the sealing material layer is 8 μm or less, the effect becomes remarkable.

The pigment according to the present invention is preferably an inorganic pigment and is a kind selected from carbon, Co ₃ O ₄ , CuO, Cr ₂ O ₃ , Fe ₂ O ₃ , MnO ₂ , SnO, TinO _2n-1 (n is an integer) or Two or more types are more preferable, and carbon is particularly preferable. These pigments have excellent color developability and good laser absorptivity. As carbon, amorphous carbon or griffite is preferable. These carbon has a property of easily processing the average particle diameter _{D 50} of the primary particles in the 1 to 100 nm.

  The pigment content is preferably 0.05 to 1% by mass, particularly preferably 0.1 to 0.8% by mass. When there is too little content of a pigment, it will become difficult to convert the light of a laser into heat energy. On the other hand, if the pigment content is too large, the sealing material layer becomes difficult to soften and flow during laser sealing, and it becomes difficult to increase the sealing strength.

The average particle diameter D50 of the primary particles of the pigment is preferably 1 to 100 nm, 3 to 70 nm, 5 to 60 nm, and particularly preferably 10 to ₅₀ nm. If the average particle diameter D ₅₀ of the primary particles of the pigment is too small, the pigments tend to aggregate together, making it difficult to disperse the pigment uniformly, and the sealing material layer is locally softened and fluidized during laser sealing. There is a risk of not. On the other hand, too large an average particle diameter D ₅₀ of the primary particles of the pigment, the pigment is difficult to uniformly disperse, sealing material layer during the laser sealing there is a possibility not to locally soften flow.

  The pigment preferably contains substantially no Cr-based oxide from the environmental viewpoint. Here, “substantially free of Cr-based oxide” refers to a case where the content of Cr-based oxide in the pigment is 1000 ppm (mass) or less.

  In the inorganic powder according to the present invention, the softening temperature is preferably 450 ° C. or lower, 420 ° C. or lower, and particularly preferably 400 ° C. or lower. When the softening temperature is higher than 450 ° C., the efficiency of laser sealing tends to decrease. The lower limit of the softening temperature is not particularly limited, but it is preferable to limit the softening temperature to 300 ° C. or higher in consideration of the thermal stability of the SnO-containing glass powder. Here, the “softening temperature” refers to a value measured with a macro-type differential thermal analysis (DTA) apparatus in a nitrogen atmosphere, DTA starts measurement from room temperature, and the rate of temperature rise is 10 ° C./min. . In addition, the softening temperature measured with the macro type | mold DTA apparatus points out temperature Ts of the 4th bending point shown in FIG.

The sealing material paste of the present invention is preferably subjected to a binder removal treatment in an inert atmosphere, and particularly preferably subjected to a binder removal treatment in an N ₂ atmosphere. If it does in this way, it will become easy to prevent the situation which SnO containing glass powder changes in the case of binder removal.

The sealing material paste of the present invention is preferably used for laser sealing in an inert atmosphere, and particularly preferably used for laser sealing in an N ₂ atmosphere. If it does in this way, it will become easy to prevent the situation which SnO containing glass powder changes in the case of laser sealing.

  The glass substrate with a sealing material layer of the present invention is a glass substrate with a sealing material layer formed by applying a sealing material paste to a glass substrate and then firing, and the sealing material paste is the above-mentioned sealing material paste, The average thickness of the sealing material layer is 5 μm or less. In this way, even if the difference in thermal expansion coefficient between the sealing material layer and the glass substrate is large, cracks and the like are hardly generated in the sealing portion and the glass substrate. Therefore, the content of the refractory filler in the inorganic powder can be reduced, and the softening fluidity of the sealing material layer can be increased. As a result, the surface roughness of the sealing material layer is reduced, so that the irradiated laser light can be efficiently converted into thermal energy, and the glass substrates are sealed together by low-power, high-speed laser irradiation. It becomes possible.

  In the glass substrate with a sealing material layer of the present invention, the surface roughness (Ra) of the sealing material layer is preferably 1.1 μm or less, 0.8 μm or less, 0.6 μm or less, and particularly preferably 0.5 μm or less. If it does in this way, the adhesiveness of a sealing material layer and a glass substrate can be improved.

  In the glass substrate with a sealing material layer of the present invention, the surface roughness (RMS) of the sealing material layer is preferably 1.7 μm or less, 1.3 μm or less, 1.0 μm or less, and particularly preferably 0.8 μm or less. If it does in this way, the adhesiveness of a sealing material layer and a glass substrate can be improved.

  As for the glass substrate with a sealing material layer of this invention, the average thickness of a sealing material layer is 8 micrometers or less, 2.2-8 micrometers, Especially 2.5-5 micrometers is preferable. In this way, the efficiency of laser sealing can be increased. If the average thickness of the sealing material layer is set to 2.2 μm or more, the variation in the thickness of the coating film is reduced, so that the reliability of laser sealing can be improved.

Moreover, a non-alkali glass substrate (for example, OA-10G manufactured by Nippon Electric Glass Co., Ltd.) is usually used for the glass substrate for organic EL devices. 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 layer with the alkali-free glass substrate. For this purpose, it is necessary to increase the content of the refractory filler in the inorganic powder, but the softening fluidity of the sealing material paste is lowered. Therefore, if the average thickness of the sealing material layer is regulated to 8 μm or less, the amount of thermal strain in the glass substrate at the time of laser sealing can be reduced, so the difference in thermal expansion coefficient between the sealing material layer and the glass substrate is large. However, cracks and the like hardly occur in the sealed portion and the glass substrate.

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

SnO-containing glass powder was prepared as follows. First, after preparing the raw materials so as to have a predetermined glass composition (mol%, SnO 59%, P ₂ O ₅ 20%, ZnO 5%, B ₂ O ₃ 15%, Al ₂ O ₃ 1%), This prepared raw material was put in an alumina crucible and melted at 900 ° C. for 1 to 2 hours under a nitrogen atmosphere. Next, the obtained molten glass was formed into a film shape with a water-cooled roller. Subsequently, the glass film was pulverized by a ball mill and classified to obtain SnO-containing glass powder. The density of the obtained SnO-containing glass powder is 3.88 g / cm ³ , and the particle size thereof is as follows: average particle size D ₅₀ : 1.5 μm, 90% particle size D ₉₀ : 3.5 μm, maximum particle size D ₉₉ : It was 5.7 μm.

Zirconium phosphate powder was used as a refractory filler. By adjusting the pulverization and classification conditions of zirconium phosphate, zirconium phosphates a and b having different particle sizes were obtained. The density of the zirconium phosphate powder is 3.80 g / cm ³ , and the particle size of a is an average particle diameter D ₅₀ : 1.6 μm, 90% particle diameter D ₉₀ : 3.3 μm, D ₉₉ : 5.1 μm. And b was an average particle diameter D ₅₀ : 1.1 μm, a 90% particle diameter D ₉₀ : 1.8 μm, and a maximum particle diameter D ₉₉ : 2.4 μm.

Ketjen black (graphite) was used as the pigment. The average particle diameter _{D 50} of the primary particles of the pigment was 20 nm.

  The particle sizes of the SnO-containing glass powder, the refractory filler, and the pigment are values measured on a volume basis by a laser diffraction particle size distribution meter.

  99.6% by mass of inorganic powder (SnO-containing glass powder 60 to 90% by volume, refractory filler 10 to 40% by volume) prepared in the above and 0.4% by mass of pigment are mixed to obtain sealing materials AD. Was made. The softening temperature and the thermal expansion coefficient were measured for the obtained sealing materials A to D. The results are shown in Table 1.

  The softening temperature is a value measured with a macro DTA apparatus. The measurement was performed at a heating rate of 10 ° C./min in a nitrogen atmosphere, and the measurement was started from room temperature.

  A thermal expansion coefficient is the value measured in the measurement temperature range 30-300 degreeC using the push rod type | mold TMA apparatus. As a measurement sample, a sintered body that was densely sintered was processed into a predetermined shape.

  Table 2 shows examples (samples No. 1 to 4) and comparative examples (samples No. 5 and 6) of the present invention.

  First, an inorganic powder and a vehicle were kneaded with a three-roll mill at a mass ratio in the table until uniform, to prepare a sealing material paste. Two types of polyethylene carbonate (hereinafter referred to as PEC) were used as the resin binder. The number average molecular weight of one PEC was 130,000, and the number average molecular weight of the other PEC was 230,000. As the solvent, propylene carbonate (hereinafter referred to as PC) and phenyl diglycol (hereinafter referred to as PhDG) were used. Note that PC / PhDG was prepared at a mass ratio of 90/10. Moreover, PEC / (PC + PhDG) was adjusted to 25/75 by mass ratio.

  Next, the above-mentioned sealing material paste was applied in a frame shape to a peripheral portion of a glass substrate having a length of 40 mm, a width of 50 mm, and a thickness of 0.5 mm (OA-10G manufactured by Nippon Electric Glass Co., Ltd.) with a screen printer. After screen printing, it was dried at 85 ° C. for 10 minutes in an air atmosphere. Subsequently, it is baked for 10 minutes at a softening temperature + 50 ° C. in a nitrogen atmosphere to incinerate the resin binder in the sealing material paste (debinding treatment) and to fix the sealing material paste to the glass substrate. Thus, a glass substrate with a sealing material layer was obtained.

  The average thickness and surface roughness (Ra, RMS) were measured for the obtained sealing material layer (fired film).

  The average thickness of the sealing material layer is a value measured with a non-contact type laser film thickness meter.

  The surface roughness (Ra, RMS) of the sealing material layer is a value measured with a surface roughness meter.

  Subsequently, a glass substrate (OA-10G manufactured by Nippon Electric Glass Co., Ltd.) having a length of 50 mm, a width of 50 mm, and a thickness of 0.5 mm is disposed on the sealing material layer in a nitrogen atmosphere, and then the sealing material layer. By irradiating a laser having a wavelength of 808 nm along the sealing material layer from the side of the glass substrate on which the glass substrate was formed, the sealing material layer was softened and flowed, and the glass substrates were hermetically sealed. The laser irradiation speed is 20 mm / s, and the laser output is as described in the table. Finally, a high-temperature, high-humidity, high-pressure test: HAST test (Highly Accelerated Temperature and Humidity Stress test) was performed on the glass substrate after hermetic sealing, and the presence or absence of peeling at the sealed portion was observed. The laser sealing property was evaluated by setting “○” as “◯” and “×” as the case where peeling was observed. The conditions of the HAST test are 121 ° C., humidity 100%, 2 atm, 24 hours.

  As apparent from Table 2, the sample No. Nos. 1 to 4 had good laser sealing properties under all laser irradiation conditions. On the other hand, Sample No. In cases 5 and 6, when the laser output was 15 W or less, peeling was observed at the sealed portion after the HAST test. Sample No. No. 5 is considered to have failed to exhibit sufficient laser sealing properties because the surface smoothness of the sealing material layer was poor. Sample No. No. 6, although the surface roughness Ra was small, the paste viscosity was too low, and the coating film thickness variation increased due to bleeding, etc., and as a result, sufficient sealing performance could be exhibited under low output conditions of 15 W or less. Probably not.

In addition to organic EL devices such as organic EL displays and organic EL lighting, the sealing material of the present invention can be used for laser sealing of solar cells such as dye-sensitized solar cells, laser sealing of lithium ion secondary batteries, and MEMS. It is also suitable for laser sealing of packages.

Claims (16)

In sealing material paste containing inorganic powder and vehicle,
The inorganic powder comprises SnO-containing glass powder;
The vehicle contains a resin binder and a solvent,
A sealing material paste, wherein the value of inorganic powder / vehicle in a mass ratio is 0.45 to 1.65.   The sealing material paste according to claim 1, wherein the vehicle includes a plurality of resin binders having different molecular weights.   The sealing material paste according to claim 1 or 2, wherein the resin binder is an aliphatic polyolefin carbonate and has a number average molecular weight of 50,000 to 500,000.   As the solvent, N, N′-dimethylformamide, ethylene glycol, dimethyl sulfoxide, dimethyl carbonate, propylene carbonate, butyrolactone, caprolactone, N-methyl-2-pyrrolidone, phenyl diglycol (PhDG), dibutyl phthalate ( It contains 1 type, or 2 or more types chosen from DBP), benzyl glycol (BzG), benzyl diglycol (BzDG), and phenyl glycol (PhG), The sealing as described in any one of Claims 1-3 characterized by the above-mentioned. Landing material paste. The SnO-containing glass powder contains, as a glass composition, mol%, SnO 35 to 70%, P ₂ O ₅ 10 to 30%, and its maximum particle size D ₉₉ is 10 μm or less. Item 5. The sealing material paste according to any one of Items 1 to 4. The sealing material paste according to any one of claims 1 to 5, wherein the inorganic powder further contains a refractory filler and has a maximum particle size _D99 of 5 µm or less.   The sealing material paste according to any one of claims 1 to 6, wherein the inorganic powder further contains a pigment. Pigment is amorphous carbon or graphite, the sealing material paste according to claim 7 having an average particle diameter D ₅₀ of the primary particles is characterized by a 1 to 100 nm.   The sealing material paste according to any one of claims 1 to 8, which is used for sealing an organic EL device.   The sealing material paste according to any one of claims 1 to 9, wherein the paste is subjected to a debinding process in an inert atmosphere.   The sealing material paste according to any one of claims 1 to 10, wherein the paste is used for laser sealing. In a glass substrate with a sealing material layer formed by applying a sealing material paste to a glass substrate and firing it,
The sealing material paste is the sealing material paste according to any one of claims 1 to 10, and an average thickness of the sealing material layer is 8 µm or less. Glass substrate.   The surface roughness (Ra) of the sealing material layer is 1.1 μm or less, and the glass substrate with a sealing material layer according to claim 12.   14. The glass substrate with a sealing material layer according to claim 12, wherein the sealing material layer has a surface roughness (RMS) of 1.7 μm or less.   A glass substrate with a sealing material layer, wherein the sealing material layer has an average thickness of 2.2 to 8 μm and a surface roughness (Ra) of the sealing material layer of 1.1 μm or less. An average thickness of a sealing material layer is 2.2 to 8 μm, and a surface roughness (RMS) of the sealing material layer is 1.7 μm or less.