Paste composition for joining ceramics and metal

Abstract

To provide a paste composition enabling a ceramic member and a metal member to be joined at high adhesion and high strength by sintering the members under air atmosphere, without necessitating special environment and precious metal, and a joining method using the paste composition.SOLUTION: According to the present invention, a paste composition for joining ceramics and metals is provided, comprising aluminum powder, an organic vehicle, and glass frit. In the paste composition, the glass frit consists of 10 to 20% by mass of SiO2, 1 to 10% by mass of MgO, 30 to 40% by mass of B2O3, 0 to 10% by mass of CaO, 0 to 10% by mass of BaO, 20 to 30% by mass of Al2O3, and 10 to 20% by mass of Li2O. A joining method using the paste composition is also provided.SELECTED DRAWING: None

Description

[Technical Field]

[0001] The present invention relates to a paste composition for joining ceramics and metals and a joining method using the same. [Background technology]

[0002] Many methods for joining ceramics and metals have been proposed and realized. For example, Japanese Patent Application Laid-Open No. 2022-024309 (Patent Document 1) discloses a method of joining a ceramic substrate and a copper or copper alloy plate by soldering. Japanese Patent Application Laid-Open No. 2023-059749 (Patent Document 2) discloses a method of directly joining an aluminum member containing 0.01 to 0.2 mass% Ti and 0.001 to 0.1 mass% B to a ceramic substrate by molten metal joining. Furthermore, Japanese Patent Application Laid-Open No. 2016-039163 (Patent Document 3) discloses a method of brazing a copper plate or an aluminum plate via a brazing filler metal. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-024309 [Patent Document 2] Patent Publication No. 2023-059749 [Patent Document 3] Japanese Patent Application Laid-Open No. 2016-039163 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the bonding methods and paste compositions used in the bonding methods described in Patent Documents 1 to 3 described above have strict conditions that require bonding between ceramics and metals in a vacuum atmosphere, under pressure, or in a batch environment, making them unsuitable for mass production. Furthermore, even in methods that allow bonding between ceramics and metals in an air atmosphere, expensive noble metals must be used as bonding materials, resulting in high costs.

[0005] Therefore, the present invention has been made in consideration of the above-mentioned problems, and aims to provide a paste composition for joining ceramics and metals, which uses aluminum powder as a main raw material and can join ceramic members and metal members without requiring a special environment such as a vacuum atmosphere or pressure, and which can obtain high joining strength by firing in an air atmosphere without using precious metals, and a joining method using the same. [Means for solving the problem]

[0006] In order to solve the above problems, the present inventors have conducted extensive research into the amount of aggregate to be blended in a paste composition for joining ceramic members and metal members, the composition of each aggregate, and other factors. As a result, they have found that the above problems can be solved by using a glass frit having a specific composition or an aluminum powder containing specific components, or by blending a specific amount of aggregate in a paste composition, and have thus completed the present invention.

[0007] That is, according to the present invention, there are provided a paste composition for joining ceramics and metals, and a joining method using the same, which comprises aluminum powder, an organic vehicle, and glass frit, wherein the glass frit contains 10% by mass or more and 20% by mass or less of SiO2, 1% by mass or more and 10% by mass or less of MgO, 30% by mass or more and 40% by mass or less of B2O3, 0% by mass or more and 10% by mass or less of CaO, 0% by mass or more and 10% by mass or less of BaO, 20% by mass or more and 30% by mass or less of Al2O3, and 10% by mass or more and 20% by mass or less of Li2O.

[0008] According to the bonding paste composition of the present invention and the bonding method using the same, the bonding of ceramic members and metal members does not require a special environment such as a vacuum atmosphere or pressure, and a high level of bonding strength can be obtained by firing in an air atmosphere without using precious metals.

[0009] Furthermore, the bonding paste composition of the present invention and the bonding method using the same enable bonding by low-temperature firing by blending a specific glass frit with aluminum powder, and as a result, bonding of the metal and ceramics becomes possible as long as the melting point of the metal member is 670°C or higher.

[0010] In the bonding paste composition of the present invention and the bonding method using the same, in order to achieve higher wettability to the base material and obtain higher bonding strength, it is preferable that the aluminum powder contains 9 mass % or more and 15 mass % or less of Si.

[0011] The bonding paste composition of the present invention preferably contains 20 to 45 parts by mass of vehicle and 1 to 40 parts by mass of glass frit per 100 parts by mass of aluminum powder. [Effects of the Invention]

[0012] The bonding paste composition of the present invention and the bonding method using the same have the excellent effect of enabling the bonding of ceramic members and metal members to be performed without requiring a special environment such as a vacuum atmosphere or pressure, and also enabling high bonding strength to be obtained by firing in an air atmosphere without using precious metals.

[0013] Furthermore, the bonding paste composition of the present invention and the bonding method using the same enable bonding at low temperatures by blending a specific glass frit with aluminum powder, and as a result, has the excellent effect of enabling bonding between metals and ceramics as long as the melting point of the metal members is 670°C or higher. DETAILED DESCRIPTION OF THE INVENTION

[0014] A bonding paste composition and a bonding method using the same according to one embodiment of the present invention will be described in detail below. Note that the present invention is not limited to the examples shown below, and various modifications are possible within the scope of the technical concept of the present invention.

[0015] The ceramic-to-metal bonding paste composition of the present invention is a paste-like composition containing aluminum powder, an organic vehicle, and glass frit. The bonding paste composition of the present invention can be produced by mixing the above-mentioned materials by a known method. For example, mixing can be performed using a disperser, a planetary mixer, a kneader mixer, or the like.

[0016] <Aluminum powder> The aluminum powder contained in the bonding paste composition exhibits high adhesion to the metal member by forming an intermediate layer at the interface between the metal member and the paste composition in which atoms are diffused between the metal member and the paste composition when the paste composition is applied to the metal member and then fired.

[0017] The shape of the aluminum particles constituting the aluminum powder is not particularly limited. Examples include spherical, flaky, irregular, polyhedral, etc. In particular, if the aluminum particles are spherical, the number of contact points between the metal member and the aluminum particles increases, and a good intermediate layer can be formed.

[0018] The aluminum powder mentioned here includes not only pure aluminum powder but also aluminum alloy powders that contain aluminum as the main component but also other components. In the strict sense, pure aluminum and aluminum alloy powders also contain unavoidable impurities.

[0019] The aluminum powder can be appropriately selected from known pure aluminum and aluminum alloys. For example, when the metal members to be joined are made of a material such as iron, copper, or stainless steel, which has a melting point significantly higher than that of aluminum (670°C or higher), pure aluminum or a known aluminum alloy can be used as the aluminum powder. Furthermore, when the metal members are made of a material whose melting point is close to that of aluminum or an aluminum alloy (600°C or higher but lower than 670°C), an aluminum-silicon alloy can be used. When the aluminum powder contains 9% to 15% by mass of Si, high adhesion to the metal members is achieved by firing at a temperature lower than the aluminum melting point of 660°C.

[0020] <Glass frit> The glass frit used in the present invention preferably contains, within a range that totals 100 mass%, 10 mass% to 20 mass% of SiO2, 1 mass% to 10 mass% of MgO, 30 mass% to 40 mass% of B2O3, 0 mass% to 10 mass% of CaO, 0 mass% to 10 mass% of BaO, 20 mass% to 30 mass% of Al2O3, and 10 mass% to 20 mass% of Li2O.

[0021] If the glass frit has a composition within the above-mentioned range, the glass frit softens upon firing, resulting in high adhesion at the interface between the ceramic member and the paste composition. The amount of glass frit blended in the bonding paste composition is not particularly limited, but is preferably 1 part by mass or more and 40 parts by mass or less, and more preferably 3 parts by mass or more and 15 parts by mass or less, per 100 parts by mass of aluminum powder. If the glass frit is within this range, it will not excessively react with the ceramic member, causing scratches, and will therefore exhibit high adhesion to the ceramic member.

[0022] <Organic vehicle> The organic vehicle may be a solvent in which various additives and resins are dissolved as needed, or a liquid or low-melting resin may be used as the organic vehicle without a solvent.

[0023] The solvent is not particularly limited, and known organic solvents such as aliphatic hydrocarbon solvents, aromatic hydrocarbon solvents, alcohol solvents, ether solvents, ester solvents, ketone solvents, and glycol ether solvents may be used alone or in combination.

[0024] More specifically, examples of aliphatic hydrocarbon solvents include compounds such as pentane, hexane, heptane, cyclohexane, and methylcyclohexane, as well as mixtures of petroleum ether, isoparaffinic oil, and naphthenic oil. Examples of aromatic hydrocarbon solvents include compounds such as benzene, toluene, xylene, ethylbenzene, and naphthalene, as well as mixtures of white spirit. Examples of alcohol solvents include methanol, ethanol, propanol, isopropanol, and butanol. Examples of ether solvents include diethyl ether and tetrahydrofuran. Examples of ester solvents include ethyl acetate, propyl acetate, butyl acetate, acetic acid, pentyl, hexyl acetate, methyl propionate, ethyl propionate, propyl propionate, butyl propionate, pentyl propionate, hexyl propionate, methyl butyrate, ethyl butyrate, propyl butyrate, butyl butyrate, pentyl butyrate, hexyl butyrate, γ-butyrolactone, and ε-caprolactone. Examples of ketone solvents include acetone, methyl ethyl ketone, diethyl ketone, cyclohexanone, etc. Examples of glycol ether solvents include cellosolve, ethyl cellosolve, butyl cellosolve, methyl carbitol, ethyl carbitol, butyl carbitol, propylene glycol monomethyl ether, propylene glycol dimethyl ether, propylene glycol monomethyl ether acetate, dipropylene glycol monomethyl ether, dipropylene glycol monomethyl ether acetate, etc.

[0025] Examples of the various additives that can be used include antioxidants, corrosion inhibitors, antifoaming agents, thickeners, tackifiers, coupling agents, electrostatic agents, polymerization inhibitors, thixotropic agents, and anti-settling agents.

[0026] Specifically, for example, polyethylene glycol ester compounds, polyethylene glycol ether compounds, polyoxyethylene sorbitan ester compounds, sorbitan alkyl ester compounds, aliphatic polycarboxylic acid compounds, phosphate ester compounds, amide amine salts of polyester acids, polyethylene oxide compounds, fatty acid amide waxes, etc. can be used.

[0027] Any known resin can be used without any particular limitation, and examples of the resin include thermosetting resins such as ethyl cellulose, nitrocellulose, polyvinyl butyral, phenolic resin, melamine resin, urea resin, xylene resin, alkyd resin, unsaturated polyester resin, acrylic resin, polyimide resin, furan resin, urethane resin, isocyanate compound, and cyanate compound, polyethylene, polypropylene, poly-α-olefin, polystyrene, ABS resin, polymethyl methacrylate, polyvinyl chloride, polyvinylidene chloride, polyvinyl acetate, polyvinyl alcohol, polyacetal, polycarbonate, polyethylene terephthalate, polybutylene terephthalate, polyphenylene oxide, polysulfone, polyimide, polyethersulfone, polyarylate, polyether ether ketone, polytetrafluoroethylene, and silicone resins, which can be used in combination of two or more.

[0028] The amount of organic vehicle to be added is not particularly limited, but for example, in order to obtain good printability, it is preferably 10 parts by mass or more and 500 parts by mass or less, and more preferably 20 parts by mass or more and 45 parts by mass or less, per 100 parts by mass of aluminum powder.

[0029] <Ceramics components> The ceramic members to be bonded using the bonding paste composition of the present invention are not particularly limited as long as they are ceramics, and examples thereof include, but are not limited to, metal oxides such as iron oxide, alumina, silica, and zirconia, nitrides such as aluminum nitride, silicon nitride, and boron nitride, carbides such as silicon carbide, and composites of two or more of these materials.

[0030] <Metal parts> The metal members to be bonded using the bonding paste composition of the present invention can be any metal with a melting point higher than that of aluminum powder, without any particular limitation. Examples include iron, gold, copper, silver, aluminum, titanium, nickel, chromium, and alloys containing two or more of these metals. Furthermore, when aluminum, an aluminum alloy, or a material with a melting point close to that of aluminum is used as the metal member, aluminum powder containing 9% by mass to 15% by mass of Si can be selected as described above.

[0031] <Joining ceramics and metals> The method for joining a ceramic member and a metal member using the bonding paste composition of the present invention involves applying the bonding paste composition of the present invention to the joining surfaces of either or both of the ceramic member and the metal member by any method, and then joining the two members together and firing them. Furthermore, the two members with their joining surfaces joined together may be dried after application or before firing as necessary to remove the solvent.

[0032] Methods for applying the paste composition to the joining surfaces include, but are not limited to, screen printing, methods using a dispenser, a bar coater, a doctor blade, and the like.

[0033] The ceramic and metal members whose joining surfaces are joined may be fired in air, under vacuum, or under an inert atmosphere, but firing in air is preferable for its simplicity. The firing may be carried out in a single heating step, or may be carried out in stages by dividing the heating into a drying step for volatilizing or removing the solvent in the paste composition, a degreasing step for removing the resin component in the vehicle, and a firing step for the aluminum powder.

[0034] The firing temperature should be such that the maximum temperature is equal to or higher than the melting point of the aluminum powder used and lower than the melting point of the metal members to be joined. The firing temperature varies depending on the members to be joined and the composition of the aluminum powder used, but is usually at least 10°C higher than the melting point of the aluminum powder and at least 10°C lower than the melting point of the metal members. Furthermore, because a high firing temperature increases costs, it is more preferable to fire at a firing temperature of 800°C or lower even when joining metal members with a melting point higher than that of aluminum.

[0035] The firing time is not particularly limited as long as it is long enough to complete the bonding between the ceramic member and the metal member. Specifically, the time for maintaining a temperature above the melting point of the aluminum powder is preferably 5 minutes or more, and more preferably 10 minutes or more. Furthermore, since productivity decreases as the firing time increases, the firing time is preferably 2 hours or less, and more preferably 1 hour or less. [Example]

[0036] 1. Preparation of bonding paste composition The bonding paste composition according to one embodiment of the present invention and the bonding paste composition of the comparative example were produced using the following raw materials and conditions (see "Table 1").

[0037] [Example 1] The volume average particle diameter (D 50100 parts by mass of aluminum powder having a particle size of 7.0 μm and 11 parts by mass of glass powder having SiO, MgO, BO, CaO, BaO, AlO, and LiO contents of 11%, 5%, 35%, 5%, 5%, 24%, and 15% by mass, respectively, were added to 35 parts by mass of a resin liquid in which ethyl cellulose was dissolved in butyl diglycol, and the mixture was mixed using a Disper mixer (device name: Homo Disper 2.5 type, manufactured by Primix), to prepare the paste composition of Example 1.

[0038] [Example 2] The volume average particle diameter (D 50 A paste composition of Example 2 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm was used.

[0039] [Example 3] The volume average particle diameter (D 50 A paste composition of Example 3 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm was used.

[0040] [Example 4] The volume average particle diameter (D 50 A paste composition of Example 4 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm was used.

[0041] [Example 5] The volume average particle diameter (D 50 A paste composition of Example 5 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 10%, 8%, 34%, 8%, 3%, 22%, and 15% by mass, respectively, were used.

[0042] [Example 6] The volume average particle diameter (D 50 The paste composition of Example 6 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 20%, 1%, 36%, 4%, 5%, 23%, and 11% by mass, respectively, were used.

[0043] [Example 7] The volume average particle diameter (D 50 The paste composition of Example 7 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 11%, 2%, 40%, 3%, 4%, 28%, and 12% by mass, respectively, were used.

[0044] [Example 8] The volume average particle diameter (D 50 The paste composition of Example 8 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 13%, 8%, 31%, 3%, 8%, 21%, and 16% by mass, respectively, were used.

[0045] [Example 9] The volume average particle diameter (D 50The paste composition of Example 8 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 19%, 3%, 35%, 8%, 3%, 21%, and 11% by mass, respectively, were used.

[0046] [Comparative Example 1] The volume average particle diameter (D 50 A paste composition of Comparative Example 1 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 17%, 5%, 36%, 5%, 5%, 23%, and 9% by mass, respectively, were used.

[0047] Comparative Example 2 The volume average particle diameter (D 50 A paste composition of Comparative Example 2 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 15%, 3%, 32%, 3%, 3%, 21%, and 23% by mass, respectively, were used.

[0048] Comparative Example 3 The volume average particle diameter (D 50 A paste composition of Comparative Example 3 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 14%, 6%, 36%, 4%, 4%, 18%, and 18% by mass, respectively, were used.

[0049] Comparative Example 4 The volume average particle diameter (D 50 A paste composition of Comparative Example 4 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 12%, 3%, 32%, 3%, 3%, 33%, and 14% by mass, respectively, were used.

[0050] Comparative Example 5 The volume average particle diameter (D 50 A paste composition of Comparative Example 5 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 13%, 5%, 32%, 5%, 12%, 21%, and 12% by mass, respectively, were used.

[0051] Comparative Example 6 The volume average particle diameter (D 50 A paste composition of Comparative Example 6 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 11%, 6%, 33%, 12%, 4%, 22%, and 12% by mass, respectively, were used.

[0052] Comparative Example 7 The volume average particle diameter (D 50The paste composition of Comparative Example 7 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 18%, 4%, 28%, 6%, 4%, 24%, and 16% by mass, respectively, were used.

[0053] [Comparative Example 8] The volume average particle diameter (D 50 A paste composition of Comparative Example 8 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 12%, 5%, 43%, 3%, 3%, 22%, and 12% by mass, respectively, were used.

[0054] Comparative Example 9 The volume average particle diameter (D 50 A paste composition of Comparative Example 9 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 15%, 0%, 36%, 4%, 6%, 25%, and 14% by mass, respectively, were used.

[0055] [Comparative Example 10] The volume average particle diameter (D 50 A paste composition of Comparative Example 10 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 12%, 13%, 35%, 3%, 3%, 22%, and 12% by mass, respectively, were used.

[0056] [Comparative Example 11] The volume average particle diameter (D 50 A paste composition of Comparative Example 11 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 8%, 8%, 36%, 4%, 4%, 26%, and 14% by mass, respectively, were used.

[0057] [Comparative Example 12] The volume average particle diameter (D 50 A paste composition of Comparative Example 12 was prepared under the same conditions as in Example 1, except that 100 parts by mass of aluminum powder (aluminum-silicon alloy powder) having a particle size of 7.0 μm and 11 parts by mass of glass powder in which the contents of SiO, MgO, BO, CaO, BaO, AlO, and LiO were 22%, 6%, 32%, 3%, 3%, 22%, and 12% by mass, respectively, were used.

[0058] 2. Evaluation of Paste Composition <Measurement of aluminum powder> The volume average particle diameter (D 50 ) indicates the particle diameter (μm) at 50% of the volume average particle diameter in the volume cumulative particle size distribution curve. The volume average particle diameter was measured using a laser diffraction / scattering particle size distribution measuring device (instrument name: Microtrac MT3000II series, manufactured by Microtrac-Bell). For example, the volume average particle diameter (D 50 ) means the particle size (μm) at a cumulative frequency of 50% in a volume cumulative particle size distribution curve in which the vertical axis is cumulative frequency (%) and the horizontal axis is particle size (μm).

[0059] <Evaluation of bonding (adhesion)> (1) Preparation of evaluation samples In order to evaluate the bonding (adhesion) between a metal member and a ceramic member using the paste composition, an evaluation sample was prepared as follows. The paste compositions of the above-mentioned Examples and Comparative Examples were printed on an Al2O3 substrate measuring 50.8 mm x 50.8 mm x 1 mm thick using a screen printer over an area of ​​50 mm x 50 mm so as to give a film thickness of 20 to 40 μm. A 50mm x 20mm x 1mm thick SUS304 plate was placed on the Al2O3 substrate so that the center of its plane overlapped the center of the printed area on the Al2O3 substrate. Similarly to the SUS304 plate, a 50mm x 20mm x 1mm thick A1050 plate (JIS aluminum wrought material A1050) was placed on the Al2O3 substrate so that the center of its plane overlapped the center of the printed area on the Al2O3 substrate. The Al2O3 substrate with the SUS304 plate overlaid and the Al2O3 substrate with the A1050 plate overlaid were each placed in a batch oven set at an ambient temperature of 100°C for 15 minutes. This operation volatilized and thermally decomposed part of the organic components in the paste composition of each sample, and dried the paste composition.

[0060] The dried sample was fired in a batch-type electric furnace. The firing profile for SUS304 plates was as follows: when using SUS304 plates, the plates were heated at a rate of 20°C / min for 20 minutes, then at a rate of 10°C / min for 30 minutes, held at 700°C for 10 minutes, and then naturally cooled to room temperature. When using A1050 plates, the plates were heated at a rate of 20°C / min for 20 minutes, then at a rate of 10°C / min for 23 minutes, held at 630°C for 10 minutes, and then naturally cooled to room temperature.

[0061] (2) Evaluation of bonding (adhesion) (2-1) Adhesion between the paste composition and the ceramic substrate The adhesion of the sample after firing was evaluated as follows. The adhesion between the paste composition and the ceramic substrate was evaluated according to the tape test method in the peel test method of JIS H 8504. For the above-mentioned fired sample, adhesive tape was applied to the exposed printed portion of the paste composition on the Al2O3 substrate and then peeled off. If no peeling of the paste composition layer occurred, it was rated as "A", if peeling of less than 3% of the applied area occurred, it was rated as "B", and if peeling of 3% or more occurred, it was rated as "F" (fail).

[0062] (2-2) Adhesion between the paste composition and SUS304 or A1050 plate To evaluate the adhesion between the paste composition and the SUS304 plate or A1050 plate, the cross sections of the bonding interface of a sample in which a SUS304 plate was bonded to an Al2O3 substrate and a sample in which an A1050 plate was bonded to an Al2O3 substrate were observed using a scanning electron microscope. If mutual diffusion of the contained elements was confirmed, the sample was rated as "A" (pass), and if mutual diffusion was not confirmed, the sample was rated as "F" (fail).

[0063] Table 1 shows the compositions of aluminum powder and glass frit in each paste composition of Examples 1 to 9 and Comparative Examples 1 to 12, and the evaluation results of the bonding (adhesion) of each paste composition. [Table 1]

[0064] <Consideration> As shown in Table 1, by comparing the paste compositions of Examples 1 to 9 and Comparative Examples 1 to 12, it was found that the paste compositions of Examples 1 to 9 preferably use a glass frit containing 10% by mass or more and 20% by mass or less of SiO2, 1% by mass or more and 10% by mass or less of MgO, 30% by mass or more and 40% by mass or less of B2O3, 0% by mass or more and 10% by mass or less of CaO, 0% by mass or more and 10% by mass or less of BaO, 20% by mass or more and 30% by mass or less of Al2O3, and 10% by mass or more and 20% by mass or less of Li2O, more preferably 4% by mass or more and 10% by mass or less of MgO and 13% by mass or more and 20% by mass or less of Li2O, thereby achieving high adhesion between the paste composition and the ceramic member and between the paste composition and the SUS304 plate, and thereby enabling high-strength joining of the ceramic member and the metal member.

[0065] Table 1 also reveals that the paste compositions of Examples 1 to 9 preferably contain at least 20 to 45 parts by mass of vehicle and 1 to 40 parts by mass of glass frit per 100 parts by mass of aluminum powder.

[0066] Furthermore, by comparing the paste compositions of Examples 4 to 9 with those of Comparative Examples 1 to 12, it was found that the paste compositions of Examples 4 to 9 use aluminum-silicon alloy powder with an Si content of 9% by mass or more and 15% by mass or less as the aluminum powder, which results in high adhesion between the paste composition and the A1050 plate, which is pure aluminum with a low melting point, and enables ceramic members and metal members to be joined with high strength.

Claims

1. The composition comprises aluminum powder, an organic vehicle, and a glass frit, The glass frit is SiO ２ is 10% by mass or more and 20% by mass or less, MgO is 1% by mass or more and 10% by mass or less, B ２ O ３ is 30% by mass or more and 40% by mass or less, CaO is 0% by mass or more and 10% by mass or less, BaO is 0% by mass or more and 10% by mass or less, Al ２ O ３ is 20% by mass or more and 30% by mass or less, and Li ２ A paste composition for joining ceramics to metals, characterized in that O is contained in an amount of 10 to 20 mass %.

2. 2. The paste composition according to claim 1, wherein the aluminum powder contains 9% by mass or more and 15% by mass or less of Si.

3. 2. The paste composition according to claim 1, wherein the blending amount of the vehicle is 20 parts by mass or more and 45 parts by mass or less, and the blending amount of the glass frit is 1 part by mass or more and 40 parts by mass or less, relative to 100 parts by mass of the aluminum powder.

4. A joining method, comprising joining a ceramic member and a metal member using the paste composition according to any one of claims 1 to 3.

5. 5. The joining method according to claim 4, wherein the melting point of the metal members is 670° C. or higher.

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