JP4941880B2 - Bismuth-based glass composition and bismuth-based sealing material - Google Patents

Description

  The present invention relates to a bismuth-based glass composition and a bismuth-based sealing material suitable for bonding, sealing, sealing, coating, and the like of electronic components.

  Conventionally, glass has been used as an adhesive material and sealing material for electronic components, and as a coating material for protecting and insulating electrodes and resistors formed on electronic components.

  These glasses are required to have various properties such as chemical durability, mechanical strength, fluidity, and electrical insulation depending on the application, but can be fired at low temperatures as a property common to all applications. Can be mentioned. Therefore, in any application, low-melting glass (for example, see Patent Document 1) containing a large amount of PbO that has an extremely large effect of lowering the melting point of glass has been widely used.

  Recently, however, environmental problems have been pointed out with respect to low-melting glass containing PbO, and it is desired to replace it with a low-melting glass containing no PbO.

Therefore, various low melting glass has been developed as an alternative to low melting glass containing PbO. Among them, bismuth-based low-melting glass (for example, see Patent Document 2) has the same characteristics as chemical melting durability and mechanical strength compared to low-melting glass containing PbO, and thus glass containing PbO. It is expected as an alternative candidate.
Japanese Unexamined Patent Publication No. Sho 63-315536 JP 2000-128574 A

  By the way, for example, when used as a sealing material of a plasma display panel (hereinafter referred to as PDP), the following heat treatment process is performed. As the sealing material, a paste in which a low-melting glass powder and a refractory filler powder are uniformly dispersed in a vehicle made of an organic solvent or a resin is used.

  First, a sealing material (paste) is applied to the peripheral portion of the back plate of the PDP, and the vehicle components are pyrolyzed or incinerated in a high temperature atmosphere, and pre-baked.

  Next, main baking of the sealing material is performed, and the front plate and the back plate of the PDP are sealed.

  Finally, the air inside the PDP is exhausted through the exhaust pipe, and a required amount of rare gas is injected to seal the exhaust pipe. In this way, the PDP is manufactured.

  In recent years, in order to improve work efficiency, the firing of the phosphor material and the temporary firing of the sealing material may be performed simultaneously. In general, when the firing temperature of the phosphor material is compared with the temporary firing temperature, the firing temperature of the phosphor material is higher and is about 500 ° C. Therefore, when the thermal stability of the sealing material is low, devitrification occurs at this point, and the fluidity in the subsequent main firing (450 to 480 ° C.) is impaired, and air-tight sealing may not be achieved.

  An object of the present invention is a bismuth-based glass that does not substantially contain PbO and can be hermetically sealed at 450 to 480 ° C. without devitrification or crystal precipitation even if pre-baked at about 500 ° C. It is to provide a composition and a bismuth-based sealing material.

The present inventors can suppress devitrification and crystal precipitation even if pre-baked at about 500 ° C. by adding 0.01 to 5 mol% of Sb ₂ O ₃ to the bismuth-based glass composition, It has been found that it can be satisfactorily sealed at 450 to 480 ° C., and is proposed as the present invention.

The bismuth-based glass composition of the present invention is expressed in mol%, Bi ₂ O ₃ 35-50%, B ₂ O ₃ 20-35%, ZnO 10-25%, BaO + SrO + MgO + CaO 3-15%, BaO 1-15%. CuO + Fe ₂ O ₃ 1 to 11%, Sb ₂ O ₃ 0.1 to 5%.

Further, the bismuth-based sealing material of the present invention is expressed in mol%, Bi ₂ O ₃ 35-50%, B ₂ O ₃ 20-35%, ZnO 10-25%, BaO + SrO + MgO + CaO 3-15%, BaO 1 1 A sealing material in which a powder made of a bismuth glass composition containing 15%, CuO + Fe ₂ O ₃ 1-11%, Sb ₂ O ₃ 0.1-5% and a refractory filler powder are mixed. The ratio is expressed by volume%, and the powder made of the bismuth glass composition is 40 to 90%, and the refractory filler powder is 60 to 10%.

The bismuth-based glass composition of the present invention can suppress devitrification and crystal precipitation even when pre-baked at a temperature of about 500 ° C. by adding 0.01 to 5 mol% of Sb ₂ O _3. It can be hermetically sealed at ˜480 ° C.

  The reason for limiting the composition of the bismuth-based glass composition of the present invention as described above is as follows.

Bi ₂ O ₃ is a main component for lowering the glass softening point and glass transition point, and its content is 30 to 50%. When the content of Bi ₂ O ₃ is less than 30%, the softening point and glass transition point of the glass tend to be high, and there is a tendency that it cannot be hermetically sealed at 450 to 480 ° C. It tends to be devitrified. The content of Bi ₂ O ₃ is preferably 33 to 45%, and more preferably 35 to 40%.

B ₂ O ₃ is essential as a glass forming component, and its content is 20 to 35%. When the content of B ₂ O ₃ is less than 20%, the glass network is not sufficiently formed and tends to be devitrified, and the fluidity necessary for operations such as adhesion, sealing, sealing, and coating is provided. It may not be obtained. On the other hand, if it exceeds 35%, the viscosity of the glass tends to increase, and it may be difficult to hermetically seal at a temperature of 450 to 480 ° C. The content of B ₂ O ₃ is preferably 15 to 30%, and more preferably 18 to 28%.

  ZnO has the effect of suppressing devitrification during glass melting, and its content is 10 to 25%. When the content is less than 10% or more than 25%, crystals are likely to precipitate in the preliminary firing step at a temperature of about 500 ° C., and the fluidity is poor and the hermetically sealed under the firing conditions of 450 to 480 ° C. There is a tendency not to. The ZnO content is preferably 13 to 22%.

  BaO, SrO, MgO and CaO have an effect of suppressing devitrification at the time of glass melting, and the total content thereof is 1 to 15%, preferably 3 to 10%. If the total amount of these components is less than 1%, it is difficult to obtain the above effect, and if it exceeds 15%, the glass transition point becomes high, and it may be impossible to hermetically seal at 450 to 480 ° C. The BaO content is preferably 1 to 15%, particularly preferably 2 to 13%. Moreover, about each content of SrO, MgO, and CaO, it is 0 to 5%, It is preferable that it is 0 to 3% especially.

The total amount of CuO and Fe ₂ O ₃ is 1 to 11%. When the total amount of CuO and Fe ₂ O ₃ is more than 11%, devitrification is likely to occur when pre-baked at a temperature of about 500 ° C. For this reason, it may not be possible to seal hermetically. On the other hand, if the total amount of CuO and Fe ₂ O ₃ is less than 1%, devitrification at the time of glass melting tends to be inhibited. More preferably, the total amount of CuO and Fe ₂ O ₃ is 3 to 8%.

Sb ₂ O ₃ is a component that is added to prevent devitrification during pre-firing and impair the fluidity at the time of sealing, and is an essential component. Further, if Sb ₂ O ₃ is used, the glass tends not to be devitrified even if it is reheated and resealed. Its content is 0.01-5%. In order to lower the softening point, it is necessary to contain a large amount of Bi ₂ O ₃ , but when it is 30% or more in terms of mol%, there is a tendency for crystals to precipitate when calcined at a temperature of about 500 ° C. Become prominent. This is caused by Bi ₂ O ₃ (bismite) formed by bismuth oxide alone at the time of pre-firing and 2Bi ₂ O ₃ .B ₂ O ₃ or 12Bi formed from Bi ₂ O ₃ and B ₂ O _{3. 2} O ₃ · B ₂ O ₃ is believed to be due to precipitation. If a large amount of these crystals are precipitated, the fluidity is hindered, but Sb ₂ O ₃ stabilizes the glass network of Bi ₂ O ₃ —B ₂ O ₃ , and a large amount of these crystals are precipitated. There is a function to suppress this. However, addition of 5% or more is not preferable because crystals tend to precipitate on the glass. The content of Sb ₂ O ₃ is preferably 0.3 to 1.5%.

  The bismuth-based glass composition of the present invention may contain the following components in addition to the components described above.

  CuO is a component that suppresses devitrification when the glass is melted, and its content is preferably 0.1 to 10%. When the content of CuO is more than 10%, the precipitation rate of crystals tends to be extremely high and the fluidity tends to deteriorate. On the other hand, if the CuO content is less than 0.1%, it is difficult to obtain the effect of suppressing devitrification when the glass is melted. The CuO content is more preferably 1 to 8%.

Fe ₂ O ₃ is a component that suppresses devitrification when the glass is melted, and the content thereof is preferably 0.1 to 10%. When Fe ₂ O ₃ exceeds 10%, the glass becomes unstable and tends to devitrify when pre-baked at a temperature of about 500 ° C. On the other hand, when the content of Fe ₂ O ₃ is less than 0.1%, it is difficult to obtain the effect of suppressing devitrification when the glass is melted. The content of Fe ₂ O ₃ is more preferably 0.3 to 5%.

It is preferable to add Al ₂ O ₃ , which is a component that suppresses devitrification during glass melting, because the precipitation of crystals can be further suppressed. The content is preferably 0 to 5%, particularly preferably 0.1 to 3%. Addition of 5% or more tends to increase the softening point of the glass and make it difficult to hermetically seal at a temperature of 450 to 480 ° C.

SiO ₂ can be added up to 1% for the purpose of enhancing the weather resistance. If it exceeds 1%, the softening point of the glass tends to be high, and it tends to be difficult to hermetically seal at a temperature of 450 to 480 ° C.

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

P ₂ O ₅ is a component that suppresses devitrification, but if its content is more than 1%, it tends to cause phase separation, which is not preferable.

MoO ₃ , La ₂ O ₃ , Y ₂ O ₅ and CeO ₂ are components that stabilize the glass. However, if the total amount of these is more than 3%, the softening point of the glass becomes high, and 450 to 480 ° C. It tends to be difficult to seal tightly at a temperature of.

PbO is preferably substantially not contained for environmental reasons. In addition, it means that it does not contain substantially, and it means that content is 0.1% or less. Further, when PbO is contained in the low melting point glass, when used as an insulator, Pb ²⁺ may diffuse into the glass and lower the electrical insulation.

The bismuth-based glass composition having the above composition does not cause devitrification or crystal precipitation even when pre-baked at a temperature of about 500 ° C., and can be hermetically sealed at a temperature of 450 to 480 ° C. Glass having a thermal expansion coefficient of about 100 to 120 × 10 ⁻⁷ / ° C. at 30 to 300 ° C. Therefore, when a material having substantially the same thermal expansion coefficient as that of the bismuth-based glass composition is bonded, sealed, covered, etc., it can be directly bonded, sealed, or covered with the powder made of the bismuth-based glass composition.

On the other hand, a material whose thermal expansion coefficient is not compatible with the bismuth glass composition, such as alumina (70 × 10 ⁻⁷ / ° C.), high strain point glass (85 × 10 ⁻⁷ / ° C.), soda plate glass (90 × 10 ^−7). When adhering, sealing, or covering such as / ° C.), a bismuth glass composition and a refractory filler powder may be mixed to form a sealing material. It is important that the thermal expansion coefficient of the sealing material is designed to be lower by about 10 to 30 × 10 ⁻⁷ / ° C. than the object to be sealed. This is for preventing distortion of the sealing material by setting the strain applied to the sealing material after compression to the compression (compression) side. In addition to adjusting the thermal expansion coefficient, for example, a refractory filler powder can be added to improve mechanical strength.

  When mixing the refractory filler powder, the mixing ratio is preferably 40 to 90% by volume of the powder made of the bismuth-based glass composition and 60 to 10% by volume of the refractory filler powder. The reason why the ratio of the two is defined in this way is that when the refractory filler powder is less than 10% by volume, the above-mentioned effect tends to be difficult to obtain. There is a tendency not to.

  As the refractory filler powder, powders of willemite, cordierite, β-eucryptite, zircon, tin oxide, mullite, quartz glass, alumina and the like can be used alone or in combination.

  In particular, willemite and cordierite are preferable because they have a small coefficient of thermal expansion and are difficult to react with bismuth glass.

  Further, it is preferable that the refractory filler powder is coated with alumina, zinc oxide, zircon, titania, zirconia or the like because the reaction between the glass and the refractory filler powder can be suppressed. In particular, alumina is preferable because it has a high melting point and hardly reacts with glass.

  The specific uses of the bismuth-based glass sealing material of the present invention include (I) a hermetic sealing material for a plasma display panel (PDP), a forming material for an insulating layer and a dielectric layer, a forming material for a barrier rib, II) A hermetic sealing material for a fluorescent display tube (VFD), a material for forming an insulating layer, and (III) a sealing material for magnetic head-cores or cores and sliders.

  A sealing material in which a bismuth-based glass composition and a refractory filler powder are mixed may be used as a sealing material in the form of a powder, but it is handled when the sealing material and vehicle are uniformly kneaded and used as a paste. Cheap.

  The vehicle mainly includes a solvent and a resin, and the resin is added for the purpose of adjusting the viscosity of the paste.

  As the 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, water, 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.

  As the resin, acrylic resin, ethyl cellulose, polyethylene glycol derivative, nitrocellulose, polymethylstyrene, polyethylene carbonate, methacrylic acid ester and the like can be used.

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

  Table 1 shows examples (samples a to e) and comparative examples (samples f to g) of bismuth-based glass compositions, and Table 2 shows examples (samples 1 to 4) of bismuth-based sealing materials. 3 shows comparative examples (samples 5 and 6), respectively. Comparative examples f and g correspond to Examples 2 and 9 of JP-A-2000-128574, respectively.

  Each sample (ag) described in Table 1 was prepared as follows.

  First, a glass batch in which raw materials such as various oxides and carbonates were prepared so as to have the glass composition shown in the table was prepared, and this was put in a platinum crucible and melted at 900 to 1000 ° C. for 1 to 2 hours.

  Next, a part of the molten glass was poured out into a stainless steel mold as a sample for measuring the coefficient of thermal expansion, and the other molten glass was formed into a thin piece with a water-cooled roller.

  Finally, the flaky glass was pulverized with a ball mill or a sieve, and passed through a sieve having an opening of 75 μm to obtain each sample having an average particle size of about 10 μm.

  Using the above samples, the density, glass transition point, softening point, and thermal expansion coefficient were evaluated. The results are shown in Table 1.

  The density was measured using a known Archimedes method.

  The glass transition point and softening point were determined by a differential thermal analyzer (DTA).

  The thermal expansion coefficient was determined by a push rod type thermal expansion measuring device.

  In the devitrification state, after holding the sample at 500 ° C. for 30 minutes, the devitrification in the sample was visually evaluated using an optical microscope (magnification 100 times). In addition, “◯” indicates that no devitrification was observed, “Δ” indicates that it was faintly devitrified, and “×” indicates that it was clearly devitrified.

As apparent from Table 1, samples a to e which are examples of the present invention have a density of 6.79 to 6.98 g / cm ³ , a glass transition point of 358 to 373 ° C., and a softening point of 431 to 449 ° C. The coefficient of thermal expansion at 30 to 300 ° C. was 105 to 112 × 10 ⁻⁷ / ° C., and no devitrification was observed.

  On the other hand, the sample f as a comparative example was slightly devitrified, and the sample g was clearly devitrified.

  Tables 2 and 3 show the sealing materials.

  First, samples b to g and refractory filler powder were mixed at the ratios shown in Tables 2 and 3 to prepare sealing material powders (samples 1 to 6).

  Willemite or cordierite was used as the refractory filler powder.

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

  The density, softening point, thermal expansion coefficient, and devitrification state were measured according to the above methods.

  As for the flow diameter, a powder having a weight corresponding to the true specific gravity of the sealing material powder is pressed into a button shape having an outer diameter of 20 mm with a mold, heated in air at a rate of 10 ° C./min, and heated at 500 ° C. for 10 minutes. The diameter of the button when held was measured and evaluated. In addition, it means that fluidity | liquidity is excellent in a flow diameter being 22 mm or more.

As apparent from Tables 2 and 3, Samples 1 to 4 have a density of 5.71 to 6.03 g / cm ³ , a softening point of 447 to 460 ° C., and a thermal expansion coefficient of 30 to 300 ° C. of 70 to 74 ×. 10 ⁻⁷ / ° C. Further, the fluid diameter was 24.0 to 26.2 mm and had good fluidity, and no devitrification was observed.

  On the other hand, samples 6 and 7 were clearly devitrified.

  The bismuth-based glass composition of the present invention is used for bonding, sealing, coating, etc. of electronic parts, specifically, display tubes such as PDP, field emission display (FED), fluorescent display tube (VFD), and cathode ray tube (CRT). And PDP barrier rib applications, PDP barrier rib applications, magnetic head-core-to-core or core-slider sealing material applications, and the like.

Claims (6)

In terms of mol%, Bi ₂ O ₃ 35-50%, B ₂ O ₃ 20-35%, ZnO 10-25%, BaO + SrO + MgO + CaO 3-15%, BaO 1-15%, CuO + Fe ₂ O ₃ 1-11%, A bismuth-based glass composition containing 0.1 to 5% of Sb ₂ O ₃ . Further 0.1 to 10% CuO, bismuth glass composition according to claim 1, characterized in that it contains Fe ₂ O ₃ 0.1~10%.   The bismuth-based glass composition according to claim 1 or 2, which does not substantially contain PbO.   The bismuth-based glass composition according to any one of claims 1 to 3, which is used for adhesion, sealing, sealing or coating.   It is the sealing material which mixed the powder which consists of the bismuth type glass composition in any one of Claims 1-3, and a refractory filler powder, Comprising: A mixing ratio is a volume% display and consists of a bismuth type glass composition. A bismuth sealing material characterized in that the powder is 40 to 90% and the refractory filler powder is 60 to 10%.   The refractory filler powder is one or more filler powders selected from the group consisting of willemite, cordierite, β-eucryptite, zircon, tin oxide, mullite, quartz glass and alumina. The bismuth-based sealing material according to claim 5.