JP7138844B2 - Sintered body using bismuth-based glass - Google Patents

Description

TECHNICAL FIELD The present invention relates to a bismuth-based glass and a sintered body using the same, and more particularly to a bismuth-based glass suitable for sealing metal members and a sintered body using the same.

Low-melting-point glass is used for sealing metal members and the like. The low-melting-point glass is required to have properties such as chemical durability, mechanical strength, electrical insulation, etc., depending on the application.

Lead-based glass containing a large amount of PbO has been widely used as a low-melting-point glass that satisfies these required properties (see Patent Document 1).

However, PbO has the problem of having a large environmental load. Therefore, it is desired to replace lead-based glass with lead-free glass, and various lead-free glasses have been developed. In particular, the bismuth-based glass described in Patent Document 2 and the like has a low melting point, so it is a strong candidate as a substitute for lead-based glass.

JP-A-63-315536 JP-A-2000-128574

However, bismuth-based glass reacts with metal members (for example, SUS, Ni alloy, kovar, etc.) when they are sealed together, causing deterioration of the metal members, and metal bismuth from bismuth-based glass. It may precipitate and lower the electrical insulation.

Therefore, the present invention has been made in view of the above circumstances. An object of the present invention is to create a bismuth-based glass in which defects are unlikely to occur.

The present inventor found that the above technical problems can be solved by strictly limiting the glass composition range of the bismuth-based glass, and proposes the present invention. That is, the bismuth-based glass of the present invention has, as a glass composition, Bi ₂ O ₃ 30 to less than 55%, B ₂ O ₃ 5 to 20%, ZnO 15 to 40%, MgO + CaO + SrO + BaO (MgO, CaO, SrO and BaO) 2 to 20%, and SiO ₂ 0 to 12%.

Moreover, the bismuth-based glass of the present invention preferably has a mass ratio of Bi ₂ O ₃ /B ₂ O ₃ of more than 1.50 and less than 6.00. Here, “Bi ₂ O ₃ /B ₂ O ₃ ” refers to the value obtained by dividing the content of Bi ₂ O ₃ by the content of B ₂ O ₃ .

In the bismuth-based glass of the present invention, the content of Li ₂ O+Na ₂ O+K ₂ O (total amount of Li ₂ O, Na ₂ O and K ₂ O) is preferably less than 0.5% by mass.

Further, the bismuth-based glass of the present invention preferably has a softening point of 470 to 550°C. Here, the "softening point" is a value measured with a macro-type differential thermal analysis (DTA) device using a glass powder having an average particle diameter _D50 of 3.0 μm as a measurement sample. DTA is performed in the air at a rate of temperature increase of 10° C./min, and the measurement is started from room temperature. The “average particle size D ₅₀ ” represents the particle size at which the cumulative amount is 50% cumulatively from the smaller size of the particles in the volume-based cumulative particle size distribution curve measured by a laser diffraction method or the like.

Further, the bismuth-based glass of the present invention preferably has a linear thermal expansion coefficient of more than 78×10 ⁻⁷ /° C. and 120×10 ⁻⁷ /° C. or less. Here, the "linear thermal expansion coefficient" is a value measured in a temperature range of 30 to 300°C with a push rod type linear thermal expansion coefficient measuring (TMA) device.

Moreover, the bismuth-based glass of the present invention preferably has a sealing temperature of 650° C. or lower in the air. Here, the "sealing temperature" is evaluated by a flow button test. Specifically, a mass of glass powder (average particle diameter D ₅₀ : 3.0 μm) corresponding to the specific gravity is dry-pressed into a button shape with an outer diameter of 20 mm using a mold, and then the button is placed on a Ni alloy substrate. After firing at various firing temperatures, the diameter of the button (flow button) after firing is measured, and the minimum temperature at which the diameter exceeds 20 mm is taken as the sealing temperature. The firing is performed by raising the temperature from room temperature to the firing temperature at a rate of 10° C./min, maintaining the temperature at the firing temperature for 10 minutes, and then decreasing the temperature from the firing temperature to the room temperature at a rate of 10° C./min.

Further, the bismuth-based glass of the present invention is preferably used for sealing metal members.

The sintered body of the present invention is a sintered body obtained by sintering glass powder made of bismuth-based glass into a predetermined shape, and the bismuth-based glass is preferably the bismuth-based glass described above. Here, "glass powder" refers to glass having an average particle diameter D50 of ₅₀ µm or less.

The bismuth-based glass of the present invention has, as a glass composition, Bi ₂ O ₃₀ to less than 55%, B ₂ O ₅ to 20%, ZnO 15 to 40%, MgO + CaO + SrO + BaO (MgO, CaO, SrO and BaO 2 to 20%, and 0 to 12% of SiO ₂ . The reasons for limiting the glass composition as described above are as follows. In addition, in description of the following content ranges, % display points out the mass %.

Bi ₂ O ₃ is a main component that lowers the softening point, but is a component that easily reacts with metal members. The content of Bi ₂ O ₃ is less than 30-55%, preferably 33-54%, more preferably 35-53%. If the content of Bi ₂ O ₃ is too small, the softening point becomes too high, making it difficult to soften and flow in a temperature range of 650° C. or lower, and sealing defects and the like tend to occur. On the other hand, when the content of Bi ₂ O ₃ increases, the metal members (for example, SUS, Ni alloy, etc.) are likely to deteriorate when they are sealed, and metal bismuth is precipitated from the bismuth-based glass. As a result, the electrical insulation tends to deteriorate.

B ₂ O ₃ is an essential component as a glass-forming component. The content of B ₂ O ₃ is 5-20%, preferably 8-16%, more preferably 10-14%. When the content of B ₂ O ₃ decreases, the thermal stability (resistance to devitrification) tends to decrease. On the other hand, if the content of B ₂ O ₃ is too high, the softening point becomes too high, making it difficult to soften and flow in a temperature range of 650° C. or less, and sealing defects and the like tend to occur.

The mass ratio Bi ₂ O ₃ /B ₂ O ₃ is preferably greater than 1.50 and less than 6.00, more preferably 2-5, and even more preferably 3-4.5. When the mass ratio of Bi ₂ O ₃ /B ₂ O ₃ becomes small, the softening point becomes too high, and softening and flowing becomes difficult in a temperature range of 650° C. or less, and sealing failures and the like tend to occur. On the other hand, when the mass ratio of Bi ₂ O ₃ /B ₂ O ₃ increases, the metal members (for example, SUS, Ni alloy, etc.) are likely to deteriorate when they are sealed. Bismuth is deposited, and the electrical insulation tends to deteriorate.

ZnO is a component that enhances thermal stability. The content of ZnO is 15-40%, preferably 20-30%, more preferably 22-28%. As the ZnO content decreases, the thermal stability tends to decrease. On the other hand, when the ZnO content increases, the coefficient of linear thermal expansion decreases, making it difficult to match the coefficient of linear thermal expansion with that of the metal member.

When the content of B ₂ O ₃ is small, it becomes important to regulate the mass ratio ZnO/Bi ₂ O ₃ . The mass ratio ZnO/Bi ₂ O ₃ is preferably 0.17-1.8, more preferably 0.3-1.5, still more preferably 0.4-1.3. As the mass ratio ZnO/Bi ₂ O ₃ decreases, the thermal stability tends to decrease. On the other hand, when the mass ratio ZnO/Bi ₂ O ₃ increases, the coefficient of linear thermal expansion decreases, making it difficult to match the coefficient of linear thermal expansion with that of the metal member. _In addition _, "ZnO/ _Bi2O3 " refers to the value obtained by dividing the content of ZnO by the content of _Bi2O3 .

MgO, CaO, SrO, and BaO are components that improve thermal stability and suppress reduction of bismuth during sealing. The total content of MgO, CaO, SrO and BaO is 2-20%, preferably 6-18%, more preferably 8-15%. If the total amount of MgO, CaO, SrO and BaO is too small, thermal stability tends to decrease. Furthermore, when metal members (for example, SUS, Ni alloy, etc.) are sealed, deterioration of the metal members is likely to occur, and metal bismuth is likely to precipitate from the bismuth-based glass, resulting in a decrease in electrical insulation. On the other hand, if the total amount of MgO, CaO, SrO and BaO is too large, the softening point becomes too high, making it difficult to soften and flow in the temperature range of 650° C. or lower, and poor sealing and the like tend to occur.

Among MgO, CaO, SrO and BaO, SrO and BaO have good compatibility with bismuth-based glass, so they have a large effect of increasing thermal stability and suppress reduction of bismuth during sealing. The effect is also great. The total amount of SrO and BaO is preferably 2-18%, more preferably 6-17%, still more preferably 8-16%. The SrO content is preferably 0 to 12%, more preferably 1 to 10%, still more preferably 3 to 7%. Also, the content of BaO is preferably 0 to 12%, more preferably 1 to 10%, still more preferably 3 to 7%. When the contents of SrO and BaO decrease, the thermal stability tends to decrease. Furthermore, when metal members (for example, SUS, Ni alloy, etc.) are sealed, deterioration of the metal members is likely to occur, and metal bismuth is precipitated from the bismuth-based glass, easily degrading electrical insulation. On the other hand, when the content of SrO and BaO increases, the softening point becomes too high, making it difficult to soften and flow in a temperature range of 650° C. or less, and sealing defects and the like tend to occur. The content of MgO is preferably 0 to 5%, more preferably 0 to 3%, still more preferably 0 to less than 1%. The CaO content is preferably 0 to 5%, more preferably 0 to 3%, even more preferably 0 to less than 1%. If the contents of MgO and CaO are too high, the softening point becomes too high, making it difficult to soften and flow in a temperature range of 650° C. or lower, and sealing defects and the like tend to occur.

The mass ratio Bi ₂ O ₃ /(MgO+CaO+SrO+BaO) is preferably 1.6-7.5, more preferably 2-5.5. When the mass ratio Bi ₂ O ₃ /(MgO+CaO+SrO+BaO) becomes small, the softening point becomes too high, making it difficult to soften and flow in a temperature range of 650° C. or lower, and poor sealing and the like tend to occur. On the other hand, when the mass ratio Bi ₂ O ₃ /(MgO+CaO+SrO+BaO) increases, the metal members (for example, SUS, Ni alloys, etc.) are likely to deteriorate when they are sealed. is deposited, and the electrical insulation tends to deteriorate. "Bi2O3/ ₍ MgO ₊ CaO+SrO ₊ BaO)" refers to a value obtained by dividing the content of Bi2O3 by the content of MgO, CaO _, SrO and BaO.

_SiO2 is a component that enhances water resistance and weather resistance. The content of SiO ₂ is 0-12%, preferably 1-10%, more preferably 3-8%. When the content of SiO ₂ decreases, it becomes difficult to obtain the above effects. On the other hand, when the content of SiO ₂ increases, the softening point becomes too high, making it difficult to soften and flow in the temperature range of 650° C. or less, and sealing defects and the like tend to occur.

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

Li ₂ O, Na ₂ O and K ₂ O are components that lower the softening point, but are components that promote devitrification. Therefore, the total and individual contents of Li ₂ O, Na ₂ O and K ₂ O are preferably 2% or less, more preferably less than 0.5%, even more preferably less than 0.1%.

Sb ₂ O ₃ is a component that enhances thermal stability. However, when the content of Sb ₂ O ₃ increases, the metal members (for example, SUS, Ni alloy, etc.) are likely to deteriorate when they are sealed, and metal bismuth is precipitated from the bismuth-based glass. As a result, the electrical insulation tends to deteriorate. Therefore, the content of Sb ₂ O ₃ is preferably 0 to less than 1%, more preferably 0 to less than 0.1%.

CuO is a component that enhances thermal stability. However, when the content of CuO increases, the metal members (for example, SUS, Ni alloy, etc.) are likely to deteriorate when they are sealed, and metal bismuth is precipitated from the bismuth-based glass, resulting in electrical Insulation tends to deteriorate. Therefore, the CuO content is preferably 0 to 3%, more preferably 0 to less than 1%, and even more preferably 0 to less than 0.1%.

P ₂ O ₅ is a component that enhances thermal stability, but when its content increases, it tends to promote phase separation of the glass. Therefore, the content of P ₂ O ₅ is preferably 2% or less, more preferably less than 0.5%, even more preferably less than 0.1%.

MoO ₃ , La ₂ O ₃ , Y ₂ O ₅ and CeO ₂ are components that improve thermal stability. It becomes difficult to soften and flow at , and sealing defects and the like are likely to occur. Therefore, the total and individual contents of MoO ₃ , La ₂ O ₃ , Y ₂ O ₅ and CeO ₂ are preferably 2% or less, more preferably less than 0.5%, still more preferably less than 0.1%. be.

For environmental reasons, it is preferably substantially free of PbO, ie the content of PbO is less than 0.1%. In addition, when PbO is added to the glass composition, Pb ²⁺ may diffuse into the glass when used as an insulator, resulting in a decrease in electrical insulation.

In addition to the above components, other components _{( Nd2O3} , _{Fe2O3 ,} etc.) may be added up to 5%.

The bismuth-based glass of the present invention preferably has the following properties.

The coefficient of linear thermal expansion is preferably more than 78×10 ⁻⁷ /° C. and 120×10 ⁻⁷ /° C. or less, more preferably 80×10 ⁻⁷ /° C. or more and 105×10 ⁻⁷ /° C. or less. . If the coefficient of linear thermal expansion is out of the above range, it becomes difficult to match the coefficient of linear thermal expansion with that of metal members such as SUS and Ni alloys.

The softening point is preferably 470-550°C, more preferably 500-540°C. If the softening point is too low, the amount of Bi ₂ O ₃ in the glass composition tends to increase, and as a result, the reactivity with metal members tends to increase. On the other hand, if the softening point is too high, the metal member and its surrounding members may be thermally deteriorated.

The sealing temperature in the atmosphere is preferably 650° C. or lower, more preferably 635° C. or lower. If the sealing temperature is too high, the metal member and its surrounding members may be thermally deteriorated.

The bismuth-based glass of the present invention is preferably in powder form. In this way, by adding a vehicle and forming a paste, it is possible to dramatically improve coating workability and the like.

The vehicle mainly consists of a solvent and a resin binder, and the resin binder is added for the purpose of adjusting the viscosity of the paste. Moreover, a surfactant, a thickening agent, etc. can also be added as needed. The prepared paste is usually applied to a substrate or the like using an applicator such as a dispenser or a screen printer, and then subjected to a binder removal step.

As a resin binder, acrylic acid ester (acrylic resin), ethyl cellulose,
Polyethylene glycol derivatives, nitrocellulose, polymethylstyrene, polyethylene carbonate, methacrylic acid esters and the like can be used.

Solvents include N,N'-dimethylformamide (DMF), α-terpineol, higher alcohols, γ-butyl lactone (γ-BL), tetralin, butyl carbitol acetate, ethyl acetate, isoamyl acetate, diethylene glycol monoethyl ether, diethylene glycol monoethyl ether acetate, benzyl alcohol, toluene, 3-
Methoxy-3-methylbutanol, triethylene glycol monomethyl ether, triethylene glycol dimethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monobutyl ether, tripropylene glycol monomethyl ether, tripropylene glycol monobutyl ether, propylene carbonate, dimethyl sulfoxide (DMSO) , N-methyl-2-pyrrolidone and the like can be used. In particular, α-
Terpineol is preferred because it has high viscosity and good solubility for resin binders and the like.

Further, if the bismuth-based glass is made into a powder form, it can be easily processed into a composite material by adding a refractory filler. As a result, it becomes easier to adjust the coefficient of linear thermal expansion and increase the mechanical strength. can.

When the refractory filler is added, the mixing ratio is preferably 45 to 99% by volume of the glass powder and 1 to 55% by volume of the refractory filler. The reason is that if the refractory filler is less than 1% by volume, the effect based on the refractory filler is poor, and if the refractory filler is more than 55% by volume, the fluidity of the composite material is significantly reduced.

Powders of willemite ceramics, β-eucryptite, cordierite, zircon ceramics, tin oxide ceramics, zirconium phosphate ceramics, mullite, quartz glass, and alumina are used alone or in combination as refractory fillers. can do.

The bismuth-based glass of the present invention is preferably processed into a sintered body obtained by sintering glass powder into a predetermined shape. In this way, it can be stably arranged on the portion to be sealed.

A sintered body is obtained by adding a vehicle to glass powder and granulating it with a spray dryer or the like, then putting the obtained granules into a mold and press molding to produce a pressed body, which is then sintered. It can be made by tying.

The bismuth-based glass of the present invention is preferably used for sealing metal members (for example, metal packages). Since the bismuth-based glass of the present invention can suppress reaction with Ni alloy, SUS, and Kovar during sealing, it is preferably used for sealing metal members made of Ni alloy, SUS, and Kovar. . It should be noted that the bismuth-based glass of the present invention is preferably used for insulating coating of metal members in addition to sealing applications.

The present invention will be described in detail below based on examples.

Table 1 shows examples of the present invention (samples Nos. 1 to 4) and comparative examples (samples Nos. 5 and 6).

Each sample in Table 1 was prepared as follows. First, a glass batch was prepared by mixing raw materials such as various oxides and carbonates so as to have the glass composition shown in the table. Next, part of the molten glass was poured into a stainless steel mold as a sample for measuring the coefficient of linear thermal expansion, and the rest of the molten glass was formed into a film using a water-cooled roller. Finally, the film-like glass was pulverized with a ball mill or a Raikai machine and then air-classified to obtain a glass powder having an average particle diameter _D50 of about 3.0 μm.

Using the above samples, the softening point, linear thermal expansion coefficient, sealing temperature, and reactivity with the Ni alloy were evaluated. Table 1 shows the results.

The coefficient of linear thermal expansion is a value measured with a TMA apparatus in a temperature range of 30 to 300°C.

The softening point is a value measured with a macro-type DTA device. The measurement was performed in the atmosphere at a temperature elevation rate of 10° C./min, and the measurement was started from room temperature.

The sealing temperature is evaluated by a flow button test. More specifically, glass powder with a mass corresponding to the specific gravity is dry-pressed into a button shape with an outer diameter of 20 mm using a mold, and then the button is placed on a Ni alloy substrate and fired at various firing temperatures. , the diameter of the button (flow button) after firing was measured, and the minimum temperature at which the diameter exceeded 20 mm was taken as the sealing temperature. In measuring the sealing temperature, the temperature was raised from room temperature to the firing temperature at a rate of 10°C/min, held at the firing temperature for 10 minutes, and then lowered from the firing temperature to room temperature at a rate of 10°C/min.

As for the reactivity with the Ni alloy, if the Ni alloy substrate did not deteriorate after the flow button test was performed at the sealing temperature shown in the table, and metal bismuth did not precipitate from the fired button, it was evaluated as "○". ", and those in which deterioration of the Ni alloy substrate occurred, or those in which metal bismuth was precipitated from the button after firing were evaluated as "x".

As can be seen from the table, sample no. Samples 1 to 4 had a sealing temperature of 645° C. or less because the glass composition was restricted to a predetermined range, and the evaluation of reactivity with the Ni alloy was good. On the other hand, sample no. In No. 5, since the sealing temperature was 670° C., the evaluation of reactivity with the Ni alloy was poor. Moreover, sample no. In No. 6, the content of Bi ₂ O ₃ was large, so the evaluation of reactivity with the Ni alloy was poor.

Claims (3)

A sintered body obtained by sintering glass powder made of bismuth-based glass into a predetermined shape,
The bismuth-based glass is As a glass composition, in mass%, Bi₂O.₃ less than 30-55%, B₂O.₃ 5-20%, ZnO 15-40%, MgO + CaO + SrO + BaO 2-20%, SiO₂ 0-12%, Li ₂ O+Na ₂ O+K ₂ O 0 to less than 0.5%containsIt has a softening point of 470 to 550 ° C and a linear thermal expansion coefficient of 78 × 10 ^-7 /°C and 120 x 10 ^-7 /°C or less, used for sealing metal memberscharacterized bysintered body. The bismuth-based glass is Mass ratio Bi₂O.₃/B₂O.₃is greater than 1.50 and less than 6.00.sintered body. The bismuth-based glass is Claim 1, characterized in that the sealing temperature is 650°C or less in the atmosphere.or 2described insintered body.