Powder material, powder-material paste, and fired film

Abstract

Provided is a powder material which contains no environmentally hazardous substances, has excellent insulating properties and acid resistance, and is inhibited from changing in color tone or forming bubbles during firing.　The powder material has a content of a glass powder of 80-99.5 mass%, a content of an inorganic pigment of 0.5-20 mass%, and a content of an inorganic filler of 0-8 mass%, and is characterized in that the glass powder comprises, in terms of mass%, 30-70% SiO2, 8-40% BaO, 0-25% CaO, 0-20% Al2O3, 0-15% B2O3, and 0-10% Zn and the inorganic pigment is any one or more members selected from among blue pigments, yellow pigments, and green pigments.

Description

Powder materials, powder material pastes and fired films

[0001] The present invention relates to a powder material, a powder material paste, and a fired film, and more particularly to a powder material, a powder material paste, and a fired film for forming an overcoat layer on a resistor or the like.

[0002] The overcoat layer is formed to protect and insulate resistors and other components formed on a support such as a plate or cylinder of alumina. A powder material paste has traditionally been used to form the overcoat layer. This powder material paste is typically a mixture of glass powder and a vehicle, with ceramic powder sometimes added as needed.

[0003] The overcoat layer is formed by applying a powder material paste to a resistor or the like, followed by firing. The overcoat layer may be plated to impart properties such as corrosion resistance, optical properties, mechanical properties, and electrical properties. In this plating process, the overcoat layer is immersed in a plating solution. The plating solution is usually an acidic solution. Therefore, when the plating process is performed, the overcoat layer must be acid-resistant. Therefore, the powder material must be acid-resistant, and lead-based glass, which has high acid resistance, is generally used (see Patent Document 1).

[0004] Furthermore, when used as an overcoat layer for enameled resistors and the like used at high rated power, the overcoat layer is required to have high insulating properties. For enameled resistors and the like, it is preferable that the overcoat layer be colored for the sake of aesthetic appearance and shielding of the internal structure, and an inorganic pigment is usually added to the powder material.

[0005] Japanese Unexamined Patent Publication No. 58-64245

[0006] In recent years, efforts have been made to reduce environmental load substances, such as PbO, and there is a strong demand for powder materials that do not contain PbO. ２To achieve a smooth surface, glass powder containing the inorganic pigment as the main component must be fired at a high temperature, for example, 800° C. or higher. During this firing, the glass powder reacts with the inorganic pigment, causing problems such as discoloration and fading of the overcoat layer and foaming.

[0007] An object of the present invention is to provide a powder material that does not contain any environmentally hazardous substances, has excellent insulating properties and acid resistance, and is inhibited from changing color and foaming when fired.

[0008] The powder material of the present invention has a glass powder content of 80 to 99.5 mass %, an inorganic pigment content of 0.5 to 20 mass %, and an inorganic filler content of 0 to 8 mass %, and the glass powder contains, in mass %, SiO ２ 30-70%, BaO 8-40%, CaO 0-25%, Al ２ O ３ 0-20%, B ２ O ３ The inorganic pigment is any one or more selected from the group consisting of blue pigments, yellow pigments, and green pigments.

[0009] By controlling the contents of the glass powder, inorganic pigment, and inorganic filler as described above, it is possible to improve the insulating properties and acid resistance of the overcoat layer and to suppress color change and foaming during firing.

[0010] The powder material of the present invention is characterized in that the inorganic pigment is substantially Cr. ２ O ３ It is preferable that the material does not contain substantially Cr. ２ O ３ "Does not contain Cr" means that the Cr in the pigment ２ O ３ This means that the content of is less than 0.1 mass%.

[0011] In the powder material of the present invention, the inorganic pigment preferably contains substantially no CoO. "Substantially no CoO" means that the CoO content in the pigment is less than 0.1% by mass.

[0012] In the powder material of the present invention, the blue pigment is preferably a Zr-Si-V based composite oxide.

[0013] In the powder material of the present invention, the yellow pigment is preferably any one or more selected from Zr-Si-Pr based composite oxide, Zr-V based composite oxide, and Sn-V based composite oxide.

[0014] In the powder material of the present invention, the green pigment is preferably a Zr-Si-Pr-V based composite oxide.

[0015] The powder material of the present invention is preferably used to form an overcoat layer.

[0016] The powder material paste of the present invention is characterized by containing the above powder material and a vehicle.

[0017] The fired film of the present invention is characterized by being a fired body of the above powder material.

[0018] According to the present invention, it is possible to provide a powder material that does not contain any environmentally hazardous substances, has excellent insulating properties and acid resistance, and suppresses color change and foaming during firing.

[0019] The powder material of the present invention has a glass powder content of 80 to 99.5 mass%, preferably 82 to 95 mass%, and particularly preferably 84 to 92 mass%, a glass powder content of 0.5 to 20 mass%, preferably 3 to 18 mass%, and particularly preferably 7 to 16 mass%, and a glass filler content of 0 to 8 mass%, preferably 0 to 5 mass%, and particularly preferably 0 to 3 mass%. If the glass powder content is too low, the insulating properties and acid resistance tend to deteriorate. On the other hand, if the glass powder content is too high, it becomes difficult to obtain an overcoat layer with a desired color tone. If the inorganic pigment content is too low, it becomes difficult to obtain an overcoat layer with a desired color tone. On the other hand, if the inorganic pigment content is too high, the insulating properties and acid resistance tend to deteriorate. If the inorganic filler content is too high, the insulating properties and acid resistance tend to deteriorate.

[0020] Next, the glass powder will be described.

[0021] (Glass Powder) The glass powder contains, in mass %, SiO ２ 30-70%, BaO 8-40%, CaO 0-25%, Al ２ O ３ 0-20%, B２ O ３ It is preferable that the content range of each component is 0 to 15%, and ZnO 0 to 10%. The reasons for restricting the content range of each component as described above are explained below. In the explanation of the content range of each component, % means mass %.

[0022] SiO ２ is a component that forms the glass skeleton and also enhances insulation properties and acid resistance. ２ The content of SiO is 30 to 70%, preferably 35 to 65%, and more preferably 40 to 60%. ２ When the content of SiO is small, the insulating property and acid resistance tend to decrease. ２ If the content of is large, the softening point tends to increase unduly.

[0023] BaO is a component that lowers the softening point and stabilizes the glass. The BaO content is 8 to 40%, preferably 10 to 35%, and more preferably 15 to 30%. If the BaO content is low, the softening point tends to increase unduly. On the other hand, if the BaO content is high, the acid resistance and thermal stability tend to decrease.

[0024] CaO is a component that lowers the softening point and stabilizes the glass, but also reduces the acid resistance. The CaO content is 0 to 25%, preferably 3 to 20%, and more preferably 5 to 17%. If the CaO content is low, the thermal stability tends to decrease. On the other hand, if the CaO content is high, the acid resistance tends to decrease.

[0025] Al ２ O ３ is a component that enhances acid resistance and thermal stability, but also significantly increases the softening point. ２ O ３ The content of Al is 0 to 20%, preferably 2 to 15%, and more preferably 4 to 12%. ２ O ３ When the content of Al is low, the acid resistance and thermal stability tend to decrease. ２ O ３ If the content of is large, the softening point tends to increase unduly.

[0026] B ２ O ３ is a component that forms a glass skeleton and further expands the vitrification range. ２ O ３ The content of is 0 to 15%, preferably 2 to 13%, and more preferably 3 to 10%. ２ O ３ When the content of B is small, the thermal stability is likely to decrease. ２ O ３ When the content is large, the acid resistance tends to decrease.

[0027] ZnO is a component that lowers the softening point. The ZnO content is 0 to 10%, preferably 1 to 8%, and more preferably 2 to 7%. When the ZnO content is low, the softening point tends to increase. On the other hand, when the ZnO content is high, the acid resistance tends to decrease.

[0028] Considering the environmental aspect, it is preferable that PbO is not substantially contained. Here, "substantially not contained PbO" means that the PbO content is less than 0.1%.

[0029] The softening point of the glass powder is preferably 700 to 920°C, 750 to 890°C, and particularly preferably 800 to 870°C. If the softening point is too low, the resistor and the like tend to react with the powder material during firing, which tends to deteriorate the characteristics of the resistor and the like. On the other hand, if the softening point is too high, the firing temperature must be increased to obtain a dense overcoat layer, which tends to cause the resistor and the like to react with the powder material, which tends to deteriorate the characteristics of the resistor and the like. Here, the "softening point" refers to the value of the fourth inflection point measured with a macro-type differential thermal analyzer (DTA).

[0030] The linear thermal expansion coefficient of the glass powder is 50 to 90 × 10 －７ / °C, particularly 55 to 80 × 10 －７ / °C. This makes it easier to prevent cracking and peeling of the overcoat layer after it is formed on a ceramic support such as alumina. Here, the "linear thermal expansion coefficient" is a value measured in the temperature range of 30 to 380°C using a thermomechanical analyzer (TMA).

[0031] Average particle size D of glass powder ５０ is preferably 50 μm or less, and the maximum particle size D ｍａｘ If the particle size of the glass powder is too large, the surface smoothness of the overcoat layer is likely to deteriorate. ５０ " refers to a value measured by a laser diffraction device, and represents the particle diameter at which the integrated amount accumulates from the smallest particle to 50% in the cumulative particle size distribution curve on a volume basis measured by the laser diffraction method. ｍａｘ " refers to a value measured using a laser diffraction device, and represents the particle size at which the integrated amount, cumulative from the smallest particle, accounts for 99% of the total on a volume-based cumulative particle size distribution curve measured using a laser diffraction method.

[0032] Next, inorganic pigments will be described.

[0033] (Inorganic Pigments) Inorganic pigments are mainly classified into oxide-based, nitride-based, and sulfide-based pigments. Since the powder material of the present invention is used after being fired at high temperatures of 700°C or higher, it is preferable that the inorganic pigment be an oxide-based pigment with high heat resistance. However, nitride-based and sulfide-based inorganic pigments, which have lower heat resistance than oxide-based pigments, are not suitable for use.

[0034] Considering the environmental aspect, inorganic pigments are essentially Cr ２ O ３ It is preferable that the inorganic pigment does not contain CoO. ５０ It is preferable to use a material with a thickness of about 0.2 to 5 μm.

[0035] The inorganic pigment is any one or more selected from a blue pigment, a yellow pigment, and a green pigment. The blue pigment is preferably a Zr-Si-V composite oxide, the yellow pigment is preferably any one or more selected from a Zr-Si-Pr composite oxide, a Zr-V composite oxide, and a Sn-V composite oxide, and the green pigment is preferably a Zr-Si-Pr-V composite oxide. This can suppress color changes (discoloration and / or fading) and foaming during firing. It can also improve the aesthetics and shielding properties of the overcoat layer. The overcoat layer exhibits a green color when a blue pigment and a yellow pigment are used in combination.

[0036] The black pigment, Co—Fe—Mn composite oxide, easily reacts with glass powder during firing, causing the overcoat layer to foam, while the green pigment, Ti—Co—Ni—Zn composite oxide, has low heat resistance, causing the overcoat layer to easily fade.

[0037] Next, the inorganic filler will be described.

[0038] (Inorganic Filler) As the inorganic filler, powders of cordierite, willemite, β-eucryptite, mullite, zircon, lead titanate, etc. can be used in order to adjust the linear thermal expansion coefficient, etc. The particle size of the inorganic filler is an average particle size D ５０ It is preferable to use a material with a thickness of about 0.2 to 5 μm.

[0039] Next, the powder material, the powder material paste, and the method for producing the fired film of the present invention will be described.

[0040] First, molten glass is formed into a film, and the resulting glass film is crushed and classified to produce glass powder. Then, the glass powder, inorganic pigment, and inorganic filler are mixed in a predetermined ratio to obtain a powder material.

[0041] The powder material and the vehicle are then mixed and kneaded in a predetermined ratio to produce a powder material paste. The vehicle may contain, for example, an organic solvent, a resin, a plasticizer, a dispersant, etc.

[0042] The organic solvent is a material for forming a paste from the glass powder, and examples thereof include terpineol (Ter), diethylene glycol monobutyl ether (BC), diethylene glycol monobutyl ether acetate (BCA), 2,2,4-trimethyl-1,3-pentanediol monoisobutyrate, and dihydroterpineol, which can be used alone or in combination. The content of the organic solvent is preferably 10 to 40 mass %.

[0043] The resin is a component that increases the strength of the film after drying and imparts flexibility, and its content is generally about 0.1 to 20 mass %. The resin may be a thermoplastic resin, specifically, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose, etc., which may be used alone or in combination.

[0044] The plasticizer is a component that controls the drying rate and provides flexibility to the dried film, and its content is generally about 0 to 10% by mass. Examples of the plasticizer that can be used include butyl benzyl phthalate, dioctyl phthalate, diisooctyl phthalate, dicapryl phthalate, dibutyl phthalate, and acetyl tributyl citrate, and these can be used alone or in combination.

[0045] As the dispersant, ionic or nonionic dispersants can be used, and ionic dispersants include polycarboxylic acid dispersants such as carboxylic acids and dicarboxylic acids, and amine dispersants, while nonionic dispersants include polyester condensation dispersants and polyhydric alcohol ether dispersants. The amount used is generally 0 to 5% by mass.

[0046] Next, a powder material paste is applied to a support such as alumina on which a resistor has been formed, using a slit coating method, dip coating method, or the like, to form an overcoat layer of a predetermined thickness, and then dried to obtain a dry film. The dried film is then fired at a temperature of 800 to 920°C for 10 to 30 minutes to form a predetermined overcoat layer (fired film). If the firing temperature is too low or the firing time (holding time) is too short, the dried film will not be sufficiently sintered, making it difficult to form a dense fired film. On the other hand, if the firing temperature is too high or the holding time is too long, the resistor and the powder material will react, which will likely deteriorate the characteristics of the resistor and the like.

[0047] Although the method of forming the overcoat layer (fired film) has been described using a powder material paste as an example, other methods may also be used, such as a green sheet method, a photosensitive paste method, or a photosensitive green sheet method.

[0048] The present invention will be described in detail below based on examples. However, the present invention is not limited to the following examples. The following examples are merely illustrative.

[0049] Tables 1 and 2 show examples of the present invention (samples Nos. 1 to 7) and a comparative example (sample No. 8).

[0050]

[0051]

[0052] (Preparation of Glass Powder) First, raw materials were prepared and uniformly mixed to obtain the glass composition shown in the table. Then, the raw materials were placed in a platinum crucible and melted at 1400°C for 2 hours. Next, a portion of the molten glass was poured into a stainless steel mold as a sample for measuring the linear thermal expansion coefficient, and the remaining molten glass was formed into a film using a water-cooled roller. The obtained glass film was pulverized in a ball mill and then air-classified to determine the average particle size D ５０ is 30 μm or less, maximum particle size D ｍａｘ The glass powder thus obtained was evaluated for its softening point.

[0053] The linear thermal expansion coefficient was measured by measuring the above-mentioned measurement sample for the linear thermal expansion coefficient in the temperature range of 30 to 380°C using a thermomechanical analyzer (TMA).

[0054] The softening point was determined as the value of the fourth inflection point measured by a macro-type differential thermal analyzer (DTA).

[0055] (Preparation of Powder Material) Subsequently, the glass powder, inorganic pigment 1, and inorganic pigment 2 were mixed in the ratios shown in the table to prepare powder materials.

[0056] Next, the powder material and a vehicle (terpineol containing 5% by mass of ethyl cellulose and 3% by mass of acetyl tributyl citrate) were mixed and kneaded using a two-screw mixer to obtain a powder material paste. The powder material paste was then applied to an alumina substrate using a baker applicator to obtain a fired film (overcoat layer) of approximately 100 μm. The applied film was then dried and fired in an electric furnace for 30 minutes at the firing temperature listed in Table 1 to form a fired film. The resulting alumina substrate with the fired film was used to evaluate its acid resistance and post-fired condition.

[0057] Acid resistance was evaluated as follows: an alumina substrate with a fired film was immersed in 0.05 mol / L sulfuric acid at 30°C for 30 minutes, washed with water, dried, and then the surface was observed. Those that were visually shiny and had no visible erosion were rated "Good", and those that were matte and had visible erosion were rated "Poor".

[0058] The condition after firing was evaluated as follows. The fired film was polished to a thickness of approximately 50 μm, and the surface condition of the polished fired film was observed under a stereomicroscope. The fired film was evaluated as "Good" when no color change or foaming was observed, and as "Poor" when color change or foaming was observed.

[0059] As is clear from the table, Samples Nos. 1 to 7 had high acid resistance and were in good condition after firing, while Sample No. 8 had foaming in the fired film.

[0060] The powder material, powder material paste, and fired film of the present invention are particularly suitable for overcoat layers, particularly overcoat layers for enamel resistors, but can also be used for other purposes, such as binders for electronic component materials and sealing materials.

Claims

1. The glass powder content is 80 to 99.5% by mass, the inorganic pigment content is 0.5 to 20% by mass, and the inorganic filler content is 0 to 8% by mass, and the glass powder contains, in mass%, SiO ２ 30-70%, BaO 8-40%, CaO 0-25%, Al ２ O ３ 0-20%, B ２ O ３ 0 to 15% of ZnO and 0 to 10% of ZnO, wherein the inorganic pigment is any one or more selected from the group consisting of a blue pigment, a yellow pigment, and a green pigment.

2. Inorganic pigments are essentially Cr ２ O ３ 2. The powder material according to claim 1, wherein the powder material does not contain:

3. The powder material according to claim 1 or 2, characterized in that the inorganic pigment contains substantially no CoO.

4. The powder material according to claim 1 or 2, wherein the blue pigment is a Zr-Si-V based composite oxide.

5. The powder material according to claim 1 or 2, characterized in that the yellow pigment is one or more selected from the group consisting of Zr-Si-Pr based composite oxide, Zr-V based composite oxide, and Sn-V based composite oxide.

6. The powder material according to claim 1 or 2, wherein the green pigment is a Zr-Si-Pr-V based composite oxide.

7. The powder material according to claim 1 or 2, which is used to form an overcoat layer.

8. A powder material paste comprising the powder material according to claim 1 or 2 and a vehicle.

9. A sintered film characterized by being a sintered body of the powder material according to claim 1 or 2.

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