JP4930897B2 - Bi2O3-B2O3 sealing material - Google Patents

Description

The present invention relates to a suitable _{B i 2 O 3 -B 2 O} 3 based sealing material for sealing electronic parts.

  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 softening 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.

For this reason, various low-melting-point glasses have been developed as substitutes for PbO-containing glass. Among them, Bi ₂ O ₃ —B ₂ O ₃ -based low melting point glass (for example, see Patent Document 2) has the same characteristics as PbO-containing glass in terms of chemical durability and mechanical strength. It is expected as an alternative candidate for contained glass.
Japanese Unexamined Patent Publication No. Sho 63-315536 JP 2000-128574 A

Patent Document 2 exemplifies bismuth-based low-melting glass compositions that can be used for applications such as adhesion, sealing, sealing, and coating of electronic components. However, this bismuth-based low-melting-point glass (Bi ₂ O ₃ —B ₂ O ₃ -based glass) composition has a high softening point and poor fluidity compared to glass containing PbO, and therefore the firing temperature is high. .

In order to lower the softening point, it is necessary to increase the content of Bi ₂ O ₃ which is a main component. However, if the content of Bi ₂ O ₃ is increased, crystals containing Bi ₂ O ₃ as constituent components can be obtained. It tends to precipitate during firing and fluidity is likely to be impaired. Therefore, the fluidity is not easily increased only by increasing the content of Bi ₂ O ₃ .

An object of the present invention is substantially free of PbO, to provide baked in PbO-containing glass and equivalent 480 ° C. below the temperature Ru can der _{B i 2 O 3 -B 2 O} 3 based sealing material That is.

The present inventors have added a component that lowers the softening point by adding 0.1 to 5 mol% of In ₂ O ₃ and / or Ga ₂ O ₃ to the Bi ₂ O ₃ —B ₂ O ₃ glass composition. It is found that even if the content of Bi ₂ O ₃ is increased, the precipitation of crystals during firing is suppressed, and a firing temperature can be achieved equivalent to that of PbO-containing glass, and is proposed as the present invention.

_Bi 2 _O 3 _-B 2 _{O 3} based sealing material of the present invention, there in _{B i 2 O 3 -B 2 O} 3 based sealing material obtained by mixing a glass powder and the refractory filler powder made of a glass composition Te, in the mixing ratio by volume percentage, the glass powder is 40% to 90%, the refractory filler powder Ri 60-10% der, and _Bi 2 _O 3 _-B 2 _{O 3} based glass composition, mol% It is characterized by containing Bi ₂ O ₃ 35 to 47.7%, B ₂ O ₃ 10 to 35%, and In ₂ O ₃ + Ga ₂ O ₃ 0.1 to 5% .

_Bi 2 _O 3 _-B 2 _{O 3} based sealing material of the present invention, _Bi 2 _O 3 _-B 2 _{O 3} based glass composition In ₂ O ₃ and / or _Ga 2 _{O 3} of the total amount 0. Contains 1-5% . Thus, even by increasing the content of Bi ₂ O ₃ is a component to lower the softening point of the glass, can suppress the precipitation of crystals during the firing. Therefore, although it is excellent in fluidity and does not substantially contain PbO, it can be fired at a temperature equal to or lower than 480 ° C. equivalent to PbO-containing glass.

The reason why the composition of the Bi ₂ O ₃ —B ₂ O ₃ -based glass composition according to the present invention is limited as described above is as follows.

Bi ₂ O ₃ is a main component for lowering the softening point of glass, and its content is 35 to 47.7 %, preferably 36 to 47.7 %, more preferably 37 to 47.7 %. is there. When the content of Bi ₂ O ₃ is less than 35%, the softening point of the glass becomes too high and it becomes difficult to fire at a temperature of 480 ° C. or less, and when it exceeds 47.7 %, devitrification is likely to occur.

B ₂ O ₃ is an essential component as a glass forming component, and its content is 10 to 35%, preferably 15 to 30%, and more preferably 18 to 28%. If the content of B ₂ O ₃ is less than 10%, the glass network is not easily formed, and thus it tends to be devitrified. For this reason, the fluidity necessary for sufficient sealing may not be obtained. On the other hand, if it exceeds 35%, the viscosity of the glass tends to be high, and firing may be difficult at a temperature of 480 ° C. or lower.

In ₂ O ₃ and Ga ₂ O ₃ are components added to prevent crystals from precipitating and fluidity from being impaired during firing, and are essential components. Moreover, devitrification can be prevented even if the sealing portion is reheated and resealed. The total amount of In ₂ O ₃ and Ga ₂ O ₃ is 0.1 to 5%, preferably 0.1 to 3%. In order to lower the softening point, it is necessary to increase the content of Bi ₂ O ₃ as a main component. However, if the content of Bi ₂ O ₃ is increased, Bi ₂ O ₃ is used as a crystalline constituent during firing. Crystals that are likely to precipitate, and fluidity is likely to be impaired. In particular, when Bi ₂ O ₃ is 35% or more in terms of mol%, the tendency becomes remarkable. As the cause, and Bi ₂ O ₃ during sintering a crystalline product formed by bismuth oxide alone (Bisumaito), Bi ₂ O ₃ and composed of B ₂ O ₃ Metropolitan _{2Bi 2 O 3 · B 2 O} 3 or 12Bi ₂ O ₃ · B ₂ O ₃ is believed to be due to precipitation as a crystal. When this crystal is precipitated, the fluidity is impaired, but In ₂ O ₃ and Ga ₂ O ₃ are selectively bonded to Bi ₂ O ₃ before the above crystals are precipitated, thereby suppressing the crystal precipitation. There is work to do. In particular, In ₂ O ₃ is superior to Ga ₂ O ₃ in this effect. However, it is not preferable to add more than 5% of the total amount of In ₂ O ₃ and Ga ₂ O ₃ because, on the contrary, crystals tend to precipitate during firing.

Bi ₂ O ₃ -B ₂ O ₃ based glass composition according to the present invention may contain the following components in addition to components described above.

  BaO, SrO, MgO and CaO have an effect of suppressing devitrification when the glass is melted, and are essential components. The total content of these 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 transition point tends to be high. The BaO content is preferably 1 to 10%, particularly preferably 2 to 10%. Further, the contents of SrO, MgO, and CaO are each preferably 0 to 5%, particularly preferably 0.5 to 3%.

  ZnO has an effect of suppressing devitrification at the time of glass melting, and its content is 5 to 30%, preferably 10 to 20%. When the content is less than 5% or more than 30%, the glass is easily crystallized at the time of firing, resulting in poor fluidity.

  CuO is a component that suppresses devitrification during glass melting, and its content is 0 to 15%, preferably 2 to 10%. If the CuO content is more than 15%, crystals tend to precipitate very easily during firing and the fluidity tends to deteriorate.

Fe ₂ O ₃ is a component that suppresses devitrification during glass melting, and its content is 0 to 5%, preferably 0.1 to 2%. When Fe ₂ O ₃ is greater than 5%, there is a tendency not to vitrified Bunsho during melting.

Moreover, it is preferable to add Al ₂ O ₃ which is a component that suppresses devitrification at the time of glass melting, because the precipitation of crystals can be further suppressed even during firing. Its content is 0 to 5%, preferably 0.1 to 3%. When the addition amount is more than 5%, the softening point of the glass becomes high and it becomes difficult to fire at a temperature of 480 ° C. or lower.

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 becomes high and it becomes difficult to fire at a temperature of 480 ° C. or lower.

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

P ₂ O ₅ is a component that suppresses devitrification at the time of melting. However, if the addition amount is more than 1%, it is not preferable because the glass tends to phase-separate at the time of melting.

MoO ₃ , La ₂ O ₃ , Y ₂ O ₅ and CeO ₂ are components that suppress the phase separation of the glass at the time of melting, but if the total amount of these is more than 3%, the softening point of the glass becomes high, It becomes difficult to fire at a temperature of 480 ° C. or lower.

PbO is preferably substantially not contained for environmental reasons. In addition, 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.

_Bi 2 _O 3 _-B 2 _{O 3} based glass composition having a composition described above, a non-crystalline glass which exhibits good fluidity at 480 ° C. temperature below the thermal expansion coefficient at 30 to 300 ° C. is about 110 to 120 is a × ^{10 -7} / ℃.

On the other hand, Bi ₂ O ₃ —B ₂ O ₃ -based glass composition and a material that does not match the thermal expansion coefficient, such as alumina (70 × 10 ⁻⁷ / ° C.), high strain point glass (85 × 10 ⁻⁷ / ° C.), When sealing soda plate glass (90 × 10 ⁻⁷ / ° C.) or the like, a glass powder made of a Bi ₂ O ₃ —B ₂ O ₃ glass composition and a refractory filler powder are mixed to form a sealing material Should be . 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 40 to 90% by volume of the glass powder made of the Bi ₂ O ₃ —B ₂ O ₃ glass composition, and 60 to 10% by volume of the refractory filler powder . The reason for defining the ratio of the two in this way is that when the refractory filler powder is less than 10% by volume, the above-described effect is hardly obtained, and when it exceeds 60% by volume, the fluidity tends to be poor.

  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 hardly react with Bi ₂ O ₃ —B ₂ O ₃ 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.

As a specific application of _Bi 2 _O 3 _-B 2 _{O 3} based sealing Chakuzairyo of the present invention, (1) sealing Chakuzairyo of plasma display panels (PDP), a (2) fluorescent display (VFD) Examples of the sealing material for the package include ( 3) a sealing material for the magnetic head and the core or the core and the slider.

A sealing material obtained by mixing a glass powder composed of a Bi ₂ O ₃ —B ₂ O ₃ glass composition and a refractory filler powder may be used as a sealing material as it is, but the sealing material and vehicle Are uniformly kneaded and used as a paste for easy handling.

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

  Solvents include N, N′-dimethylformamide (DMF), α-terpineol, higher alcohol, γ-butyrolactone (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, ethyl cellulose, polyethylene glycol derivatives, 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.

Tables 1 to 3 show glass compositions of Examples (samples a to m) and Comparative Examples (samples n to o). Sample h is a reference example.

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

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

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

  Finally, the glass flakes were pulverized with a ball mill and passed through a sieve having an opening of 105 μm to obtain samples having an average particle diameter of about 10 μm.

  Using the above samples, the glass transition point, softening point, thermal expansion coefficient, firing temperature and gloss were evaluated.

  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.

  The firing temperature was evaluated as follows.

  First, a sample having a mass corresponding to the true specific gravity of each sample was put into a mold and pressed into a button shape having an outer diameter of 20 mm and a height of about 5 mm. Next, this button was placed on a plate glass, placed in an electric furnace, heated at a rate of 10 ° C./min, and held at various temperatures for 30 minutes. Of the buttons having an outer diameter of 21 to 22 mm, the firing temperature of the button fired at the lowest temperature was defined as the firing temperature of the sample.

  For crystallization, the button was held at the firing temperature for 30 minutes, and then the inside of the button was observed using an optical microscope to evaluate the presence or absence of crystals.

As is apparent from Tables 1 to 3, samples a to m which are examples of the present invention have a glass transition point of 328 to 365 ° C, a softening point of 395 to 435 ° C, and a thermal expansion coefficient of 105 to 30 to 300 ° C. It was -119 * 10 < ^-7 > / degreeC, and the calcination temperature was 470 degrees C or less. Moreover, as for the baking state, the crystal | crystallization did not precipitate in all the samples am, and the surface had glossiness.

  On the other hand, samples o and p, which are comparative examples, had a firing temperature of 470 ° C. or less, but crystals were precipitated and the surface was not glossy.

  Tables 4 to 6 show sealing materials. In addition, in the column of the filler in a table | surface, A points out willemite and B points out cordierite.

Next, samples a to m and refractory filler powder were mixed at the ratios shown in Tables 4 to 6 to prepare sealing material powders (samples 1 to 15). Sample No. 1 to 7 and 9 to 13 are examples of the present invention. Reference numerals 14 and 15 denote comparative examples, respectively. Sample No. 8 is a reference example.

Samples 1 to 4 are sealing materials for VFD, and are materials for sealing two soda glass plates (coefficient of thermal expansion 90 × 10 ⁻⁷ / ° C.). Samples 5 to 15 are sealing materials for PDP, and are materials for sealing two high strain point glass plates (coefficient of thermal expansion 85 × 10 ⁻⁷ / ° C.).

  Moreover, willemite or cordierite was used for the refractory filler powder.

Willemite is prepared by blending zinc oxide, optical stone powder and aluminum oxide in a composition of ZnO 70%, SiO ₂ 25%, Al ₂ O ₃ 5% by mass, and after mixing, firing at 1440 ° C. for 15 hours. Then, the fired product was pulverized and passed through a 250 mesh stainless steel sieve to obtain a powder having an average particle size of 10 μm. Cordierite is prepared by mixing magnesium oxide, aluminum oxide, and optical stone powder in a ratio of 2MgO · 2Al ₂ O ₃ · 5SiO ₂ , mixing and firing at 1400 ° C. for 10 hours. The powder was pulverized and passed through a 250 mesh stainless steel sieve to obtain an average particle size of 10 μm.

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

  The flow diameter is a temperature described in the table by pressing a powder having a weight corresponding to the true specific gravity of the sealing material powder into a button shape having an outer diameter of 20 mm using a mold and raising the temperature in air at a rate of 10 ° C./min. The diameter of the button when held for 10 minutes was measured and evaluated. In addition, it means that fluidity | liquidity is excellent in a flow diameter being 21 mm or more.

  Resealability was evaluated as follows.

  First, each sample and acrylic resin-containing α-terpineol were uniformly kneaded to form a paste, and then linear (80 × 100 × 3 mm) at the end of a substrate (100 × 100 × 3 mm) made of the same material as the material to be sealed. × 3 × 3 mm) and dried at 120 ° C. for 15 minutes. Next, the substrate was held at a temperature 10 ° C. higher than the firing temperature described in the table for the time described in the table, and then left in the room to cool the substrate. Subsequently, a glass plate having a thickness of 150 μm was placed in the middle of the substrate, and the substrates with the same dimensions were covered from above. Then, both substrates were fixed with clips, and fired again under the conditions described in the table.

  Evaluation was made as “◯” when the distance between the substrates was 150 μm after reflowing by firing, and “X” when the distance between the substrates was larger than 150 μm without sufficiently softening and flowing again. In addition, what was "(circle)" by this evaluation is considered that the devitrification did not arise in the heat processing at the time of binder removal.

As is clear from Tables 4 to 6, Samples 1 to 13 had a coefficient of thermal expansion of 70.6 to 79.4 × 10 ⁻⁷ / ° C. at 30 to 300 ° C. Moreover, the flow diameter of 21.0-21.9mm was shown on the baking conditions shown in the table | surface, and it had favorable fluidity | liquidity. Further, no crystal was deposited, and the resealability was excellent.

  On the other hand, in Samples 14 and 15, crystals were precipitated and the resealability was poor.

  In Samples 14 and 15, the resealability was not good because the crystals had already precipitated during the first firing, and the crystals grew during the second firing, preventing the softening flow of the glass. it is conceivable that.

The Bi ₂ O ₃ —B ₂ O ₃ sealing material of the present invention is used for sealing electronic parts, specifically, PDP, field emission display (FED), surface electric field display (SED), VFD, cathode ray tube (CRT). ) sealing the display tube, such as applications, magnetic head - is suitable for sealing application of cores or core and the slider or the like.

Claims (6)

It is a sealing material in which a glass powder composed of a Bi ₂ O ₃ —B ₂ O ₃ glass composition and a refractory filler powder are mixed, and the mixing ratio is expressed by volume%, and the glass powder is 40 to 90%, refractory filler powder is 60 to 10%, and _Bi 2 _O 3 _-B 2 _{O 3} based glass composition, by _{mol%, Bi 2 O 3 35~ 47.7%} , B 2 O 3 10~ A Bi ₂ O ₃ —B ₂ O ₃ sealing material containing 35% and In ₂ O ₃ + Ga ₂ O ₃ 0.1 to 5%. Bi ₂ O ₃ -B ₂ O ₃ based glass composition, in _{mol%, BaO + SrO + MgO + Bi} 2 O according to claim 1, characterized in that CaO containing 1~15% _{3 -B} 2 _O 3 system sealing Material . Bi ₂ O ₃ -B ₂ O ₃ based glass composition, in mol%, 5 to 30% ZnO, claim wherein 0 to _15% CuO, in that it contains _Fe 2 O 3 _0~5% 1 Or Bi ₂ O ₃ —B ₂ O ₃ -based sealing material according to 2 ; Bi ₂ O ₃ -B ₂ O ₃ based glass composition is substantially _Bi 2 _O 3 _-B 2 _{O 3} based sealing according to any one of claims 1-3, characterized in that do not contain PbO Material . Refractory filler powder, to willemite, cordierite, beta-eucryptite, oxidation tin, mullite, characterized in that it is a one or two or more filler powder selected from the group consisting of quartz glass and alumina _Bi 2 _O 3 _-B 2 _{O 3} based sealing material according to any one of claims 1 to 4. Bi ₂ O ₃ -B ₂ O ₃ based sealing material according to any one of claims 1 to 5, characterized in that for use in fluorescent display tube or the sealing of the plasma display panel.