WO2016017732A1 - Bismuth glass composition, powder material and powder material paste - Google Patents

Bismuth glass composition, powder material and powder material paste Download PDF

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Publication number
WO2016017732A1
WO2016017732A1 PCT/JP2015/071601 JP2015071601W WO2016017732A1 WO 2016017732 A1 WO2016017732 A1 WO 2016017732A1 JP 2015071601 W JP2015071601 W JP 2015071601W WO 2016017732 A1 WO2016017732 A1 WO 2016017732A1
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Prior art keywords
powder material
mass
content
glass composition
powder
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PCT/JP2015/071601
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French (fr)
Japanese (ja)
Inventor
久美子 姫井
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日本電気硝子株式会社
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Publication of WO2016017732A1 publication Critical patent/WO2016017732A1/en

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Classifications

    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/062—Glass compositions containing silica with less than 40% silica by weight
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/062—Glass compositions containing silica with less than 40% silica by weight
    • C03C3/064—Glass compositions containing silica with less than 40% silica by weight containing boron
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/062—Glass compositions containing silica with less than 40% silica by weight
    • C03C3/064—Glass compositions containing silica with less than 40% silica by weight containing boron
    • C03C3/066—Glass compositions containing silica with less than 40% silica by weight containing boron containing zinc
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
    • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/083—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound
    • C03C3/085—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal
    • C03C3/087—Glass compositions containing silica with 40% to 90% silica, by weight containing aluminium oxide or an iron compound containing an oxide of a divalent metal containing calcium oxide, e.g. common sheet or container glass
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C3/00—Glass compositions
    • C03C3/04—Glass compositions containing silica
    • C03C3/076—Glass compositions containing silica with 40% to 90% silica, by weight
    • C03C3/089—Glass compositions containing silica with 40% to 90% silica, by weight containing boron
    • C03C3/091—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium
    • C03C3/093—Glass compositions containing silica with 40% to 90% silica, by weight containing boron containing aluminium containing zinc or zirconium
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
    • C03C8/14—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions
    • C03C8/16—Glass frit mixtures having non-frit additions, e.g. opacifiers, colorants, mill-additions with vehicle or suspending agents, e.g. slip
    • C—CHEMISTRY; METALLURGY
    • C03—GLASS; MINERAL OR SLAG WOOL
    • C03C—CHEMICAL COMPOSITION OF GLASSES, GLAZES OR VITREOUS ENAMELS; SURFACE TREATMENT OF GLASS; SURFACE TREATMENT OF FIBRES OR FILAMENTS MADE FROM GLASS, MINERALS OR SLAGS; JOINING GLASS TO GLASS OR OTHER MATERIALS
    • C03C8/00—Enamels; Glazes; Fusion seal compositions being frit compositions having non-frit additions
    • C03C8/24—Fusion seal compositions being frit compositions having non-frit additions, i.e. for use as seals between dissimilar materials, e.g. glass and metal; Glass solders

Definitions

  • the present invention relates to a bismuth-based glass composition, a powder material, and a powder material paste.
  • the present invention relates to a bismuth-based glass composition, a powder material, and a powder material paste suitable for forming an insulating protective layer on a varistor element body and an electronic circuit.
  • the insulating protective layer is formed to protect and insulate electrodes, resistors, etc. formed on a soda lime glass substrate, an alumina substrate or the like. It is also formed to protect and insulate the varistor element body.
  • a powder material paste has been used to form an insulating protective layer. This powder material paste is generally a mixture of glass powder and vehicle, and ceramic powder may be added as necessary.
  • the insulating protective layer is formed by applying a powder material paste on an electrode or the like and then baking it.
  • the firing temperature is limited to 800 ° C. or less in order to prevent a situation where the properties of the electrode and the like deteriorate due to the reaction between the electrode and the powder material.
  • the powder material (powder material paste) is required to be able to be fired at a temperature of 800 ° C. or lower.
  • the powder material is required not to cause warping of the substrate or the varistor element body after firing and not to be easily peeled off from the substrate or varistor element body.
  • Patent Document 1 PbO—B 2 O 3 —SiO 2 -based glass has been used as a powder material that satisfies the above required characteristics (see Patent Document 1).
  • Patent Documents 2 to 4 describe Bi 2 O 3 —B 2 O 3 —ZnO-based glasses.
  • the electronic circuit on which the insulating protective layer is formed may be subjected to a plating treatment in order to impart characteristics such as corrosion resistance, optical characteristics, mechanical characteristics, and electrical characteristics.
  • the insulating protective layer is immersed in the plating solution.
  • the plating solution is usually an acidic solution. For this reason, when plating is performed, the insulating protective layer is required to have acid resistance. That is, acid resistance is required for the powder material.
  • the Bi 2 O 3 —B 2 O 3 —ZnO-based glasses described in Patent Documents 2 to 4 have low acid resistance, so that they are easily eroded by the plating solution, and it is difficult to maintain characteristics such as insulation. Have.
  • the present invention has been made in view of the above circumstances, and its technical problem is that it can be fired at a temperature of 800 ° C. or less without containing PbO, and warps from the substrate or the like from the substrate or the like. It is to create a bismuth-based glass composition, a powder material, and a powder material paste that do not easily peel and are not easily eroded by a plating solution.
  • the present inventor adopted bismuth-based glass as a glass system and strictly controlled the content ratio of SiO 2 , ZrO 2 , and Al 2 O 3 in the glass composition, thereby The present inventors have found that technical problems can be solved and propose the present invention. That is, the bismuth-based glass composition of the present invention has a glass composition of Bi 2 O 3 40 to 55%, SiO 2 28 to 40%, ZrO 2 over 5 to 9%, Al 2 O 3 2 to 10%, B 2 O 3 0 to 5%, and the mass ratio (SiO 2 + ZrO 2 ) / Al 2 O 3 is smaller than 15.
  • Bismuth glass generally has low acid resistance.
  • the content of SiO 2 is restricted to 25% by mass or more, and the content of ZrO 2 is restricted to more than 5% by mass. By doing so, acid resistance is improved.
  • the content of ZrO 2 is excessive when the content of SiO 2 is large, zircon (ZrSiO 4 ) crystals that reduce acid resistance during molding are precipitated, making it difficult to ensure desired acid resistance. There is. Further, the glass may be phase-divided during molding, and it may be difficult to ensure desired acid resistance.
  • the content of Al 2 O 3 in the glass composition is 2% by mass or more and the mass ratio (SiO 2 + ZrO 2 ) / Al 2 O 3 is regulated to less than 15.
  • the precipitation of zircon crystals and the phase separation of glass during molding are suppressed.
  • the content of MgO is 5% by mass or less
  • the content of CaO is 5% by mass or less
  • the content of SrO is 5% by mass or less
  • the content of ZnO is 5% by mass or less. It is preferable that
  • the bismuth-based glass composition of the present invention does not substantially contain PbO.
  • substantially free of PbO means that PbO is allowed to be mixed in at an impurity level, but avoids aggressive introduction. Specifically, the content of PbO in the glass composition Is less than 1000 ppm.
  • the powder material of the present invention preferably has a softening point of 800 ° C. or lower.
  • the “softening point” refers to the temperature at the fourth inflection point measured with a macro-type differential thermal analyzer (DTA).
  • the powder material paste of the present invention is a powder material paste containing a powder material and a vehicle, wherein the powder material is the powder material described above.
  • Bi 2 O 3 is a component that lowers the softening point, but is a component that lowers acid resistance.
  • the content of Bi 2 O 3 is 40 to 55%, preferably 41 to 54%, 42 to 53%, particularly 43 to 52%.
  • the softening point is unduly raised and it becomes difficult to fire at a temperature of 800 ° C. or lower.
  • the content of Bi 2 O 3 increases, the acid resistance tends to decrease, and the insulating protective layer is easily eroded by the plating solution, and as a result, it becomes difficult to insulate and protect the electrodes of the electronic circuit.
  • the raw material cost is likely to increase.
  • SiO 2 is a component that forms a glass skeleton and a component that increases acid resistance.
  • the content of SiO 2 is 28 to 40%, preferably 29 to 38%, in particular 30 to 36%.
  • the acid resistance is likely to be lowered, and the insulating protective layer is easily eroded by the plating solution. As a result, it is difficult to insulate and protect the electrodes of the electronic circuit.
  • the content of SiO 2 is increased, the softening point is unreasonably raised and it becomes difficult to fire at a temperature of 800 ° C. or lower.
  • Al 2 O 3 is a component that enhances acid resistance and is a component that stabilizes glass, particularly a component that suppresses the precipitation of zircon crystals.
  • the content of Al 2 O 3 is 2 to 10%, preferably 2.5 to 9%, particularly 3 to 8%.
  • the content of Al 2 O 3 is reduced, the glass becomes unstable and zircon crystals are likely to precipitate during molding.
  • the content of Al 2 O 3 is increased, the softening point is unreasonably raised and it becomes difficult to fire at a temperature of 800 ° C. or lower.
  • the mass ratio (SiO 2 + ZrO 2 ) / Al 2 O 3 is 15 or less, preferably 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, particularly 9 or less.
  • the mass ratio (SiO 2 + ZrO 2 ) / Al 2 O 3 is excessive, zircon crystals are likely to precipitate during molding, and the glass is likely to be phase-separated.
  • CaO is a component that lowers the softening point and is a component that stabilizes the glass.
  • the content of CaO is preferably 0 to 5%, 0 to 4%, particularly 0 to 3%.
  • the content of CaO is increased, the acid resistance is likely to be lowered, and the insulating protective layer is easily eroded by the plating solution. As a result, it is difficult to insulate and protect the electrodes of the electronic circuit.
  • ZnO is a component that lowers the softening point but is a component that reduces acid resistance.
  • the content of ZnO is 0 to 5%, preferably 0 to 4%, particularly 0 to 3%.
  • the content of ZnO is increased, the acid resistance is significantly reduced, and the insulating protective layer is easily eroded by the plating solution, and as a result, it becomes difficult to insulate and protect the electrodes of the electronic circuit.
  • Cs 2 O, Rb 2 O, or the like may be introduced up to 5%, particularly up to 1%, alone or in total.
  • Y 2 O 3 , La 2 O 3 , Ta 2 O 5 , SnO 2 , TiO 2 , Nb 2 O 5 , P 2 O 5 , CuO , CeO 2 , V 2 O 5, etc. may be introduced in a total amount or independently up to 10%, particularly up to 1%.
  • PbO is a component that lowers the softening point, but it is also an environmentally hazardous substance, so it is preferable to avoid substantial introduction.
  • the powder material of the present invention is a powder material containing a glass powder made of the bismuth-based glass composition and a ceramic powder, wherein the glass powder content is 50 to 100% by mass, and the ceramic powder content is 0. It is characterized by ⁇ 50 mass%.
  • the glass powder can be produced, for example, by forming molten glass into a film and then crushing and classifying the obtained glass film.
  • the average particle diameter D 50 of the glass powder is preferably 3.0 ⁇ m or less, and the maximum particle diameter D max is preferably 20 ⁇ m or less.
  • the “average particle diameter D 50 ” refers to a value measured with a laser diffractometer, and in an accumulated particle size distribution curve based on volume when measured by a laser diffraction method, the accumulated amount is accumulated from the smaller particle.
  • the particle diameter is 50%.
  • Maximum particle size D max refers to a value measured by a laser diffractometer, and in the volume-based cumulative particle size distribution curve measured by the laser diffraction method, the accumulated amount is accumulated from the smaller particle.
  • the particle size is 99%.
  • the content of the ceramic powder is preferably 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, and particularly less than 1% by mass. If the ceramic powder is too much, the proportion of the glass powder becomes relatively small, and it becomes difficult to form a dense insulating protective layer, so that the insulating protective layer is easily eroded by the plating solution. It becomes difficult to insulate and protect the electrodes. If ceramic powder is added, the thermal expansion coefficient, mechanical strength, and acid resistance of the powder material can be adjusted.
  • the ceramic powder can be used as the ceramic powder.
  • alumina, zirconia, mullite, silica, cordierite, titania, tin oxide, and the like can be added.
  • the softening point is preferably 800 ° C. or lower, 790 ° C. or lower, particularly 680 to 780 ° C. If the softening point is too high, in order to obtain a dense insulating protective layer, the firing temperature must be increased, in which case the electrode and the powder material react and the characteristics of the electrode and the like are likely to deteriorate. .
  • the thermal expansion coefficient is preferably 45 to 65 ⁇ 10 ⁇ 7 / ° C., particularly 50 to 60 ⁇ 10 ⁇ 7 / ° C. If it does in this way, it will become easy to prevent the curvature of a board
  • the “thermal expansion coefficient” is a value measured in a temperature range of 30 to 300 ° C. by a thermomechanical analyzer (TMA).
  • the powder material paste of the present invention is a powder material paste containing a powder material and a vehicle, wherein the powder material is the powder material described above.
  • the vehicle is a material for dispersing glass powder into a paste, and is usually composed of a thermoplastic resin, a plasticizer, a solvent, and the like.
  • the powder material paste can be prepared by preparing a powder material and a vehicle, and mixing and kneading them at a predetermined ratio.
  • Thermoplastic resin is a component that increases the film strength after drying and also a component that imparts flexibility.
  • the content of the thermoplastic resin in the powder material paste is preferably 0.1 to 20% by mass.
  • the thermoplastic resin polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose and the like are preferable, and it is preferable to use one or more of these.
  • Solvent is a component for dissolving the thermoplastic resin.
  • the content of the solvent in the powder material paste is preferably 10 to 30% by mass.
  • the solvent terpineol, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol monoisobutyrate and the like are preferable, and it is preferable to use one or more of these.
  • a powder material paste is applied on an electronic circuit on which electrodes, resistors, etc. are formed by a screen printing method, a batch coating method, After forming a coating layer having a predetermined thickness, it is dried to obtain a dry film. Thereafter, the predetermined insulating protective layer (baked film) can be formed by baking the dried film at a temperature of 700 to 800 ° C. for 5 to 20 minutes. If the firing temperature is too low or the firing time (holding time) is too short, the dried film will not sinter sufficiently, 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 electrode and the powder material react with each other, and the characteristics of the electrode and the like easily deteriorate.
  • the method for forming the insulating protective layer the method using a powder material paste has been described as an example, but other methods may be adopted.
  • a method such as a green sheet method, a photosensitive paste method, or a photosensitive green sheet method may be adopted.
  • the bismuth-based glass composition, powder material and powder material paste of the present invention are preferably used for forming an insulating protective layer, and particularly preferably used for forming an insulating protective layer on a varistor element body.
  • electrodes, resistors, and the like are formed on the varistor element body made of ZnO oxide, and an insulating protective layer is formed thereon. Thereafter, a plating treatment with a plating solution is performed.
  • the bismuth-based glass composition, the powder material, and the powder material paste of the present invention can be fired at a temperature of 800 ° C. or less without containing PbO, and warp of the varistor element body and the varistor element body. It is particularly suitable for this application because it does not easily peel off from the film and is not easily eroded by the plating solution.
  • Table 1 shows examples (samples Nos. 1 to 4) and comparative examples (samples Nos. 5 and 6) of the present invention.
  • Each sample was prepared as follows. First, raw materials were prepared and mixed uniformly so as to have the glass composition shown in the table. Next, it was put in a platinum crucible and melted at 1350 to 1450 ° C. for 2 hours, and then formed into a film.
  • the above glass film was pulverized with a ball mill and then classified into an air stream to obtain a glass powder having an average particle size D 50 of 3.0 ⁇ m or less and a maximum particle size D max of 20 ⁇ m or less.
  • the softening point and thermal expansion coefficient were evaluated using the obtained glass powder.
  • Softening point is the temperature of the fourth inflection point measured with a macro-type differential thermal analyzer (DTA).
  • DTA differential thermal analyzer
  • the coefficient of thermal expansion was determined by pressing each glass powder and firing it at (softening point +10) ° C., then processing to a diameter of 5 mm and a length of 20 mm to obtain a measurement sample, and then a thermomechanical analyzer (TMA) ) Measured in a temperature range of 30 to 300 ° C.
  • TMA thermomechanical analyzer
  • the glass powder and the vehicle were mixed and kneaded in a three-roll mill to obtain a powder material paste.
  • the coated film is dried, and the temperature is (softening point + 10) ° C. in an electric furnace. Bake for 10 minutes at temperature. Acid resistance was evaluated using the obtained substrate with a fired film. Specifically, the substrate with the fired film was immersed in 5% by mass sulfuric acid at 40 ° C. for 5 hours, washed with water, dried, then measured for mass decrease, and evaluated the rate of mass decrease before and after immersion. In addition, it means that acid resistance is so low that the ratio of mass reduction is large.
  • sample No. Nos. 1 to 4 could be fired at a temperature of 800 ° C. or lower due to their low softening point, and further had good moldability and acid resistance.
  • Sample No. No. 5 had a low softening point, but a slight phase separation tendency was observed. As a result, moldability and acid resistance were low.
  • Sample No. No. 6 had poor moldability and acid resistance.
  • the bismuth-based glass composition, powder material, and powder material paste of the present invention are suitable for forming an insulating protective layer on a varistor element body and an electronic circuit. It can also be applied to uses such as wearing materials.

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  • Chemical & Material Sciences (AREA)
  • Life Sciences & Earth Sciences (AREA)
  • Engineering & Computer Science (AREA)
  • Chemical Kinetics & Catalysis (AREA)
  • General Chemical & Material Sciences (AREA)
  • Geochemistry & Mineralogy (AREA)
  • Materials Engineering (AREA)
  • Organic Chemistry (AREA)
  • Glass Compositions (AREA)

Abstract

The present invention addresses the technical problem of inventing: a bismuth glass composition which is able to be fired at a temperature of 800°C or less and is not susceptible to warping of the substrate or the like and separation from a substrate or the like, while being not susceptible to erosion by a plating solution even in cases where the bismuth glass composition does not contain PbO; a powder material; and a powder material paste. A bismuth glass composition according to the present invention is characterized by containing as a glass composition, in mass%, 40-55% of Bi2O3, 28-40% of SiO2, more than 5% but 9% or less of ZrO2, 2-10% of Al2O3 and 0-5% of B2O3, while having a (SiO2 + ZrO2)/Al2O3 mass ratio smaller than 15.

Description

ビスマス系ガラス組成物、粉末材料及び粉末材料ペーストBismuth glass composition, powder material and powder material paste
　本発明は、ビスマス系ガラス組成物、粉末材料及び粉末材料ペーストに関し、例えば、バリスタ素体、電子回路上の絶縁保護層の形成に好適なビスマス系ガラス組成物、粉末材料及び粉末材料ペーストに関する。 The present invention relates to a bismuth-based glass composition, a powder material, and a powder material paste. For example, the present invention relates to a bismuth-based glass composition, a powder material, and a powder material paste suitable for forming an insulating protective layer on a varistor element body and an electronic circuit.
　絶縁保護層は、ソーダライムガラス基板、アルミナ基板等に形成された電極、抵抗体等を保護、絶縁するために形成される。またバリスタ素体等を保護、絶縁するためにも形成される。従来から、絶縁保護層の形成には、粉末材料ペーストが用いられている。この粉末材料ペーストは、一般的に、ガラス粉末とビークルの混合物であり、必要に応じて、セラミック粉末が添加される場合がある。 The insulating protective layer is formed to protect and insulate electrodes, resistors, etc. formed on a soda lime glass substrate, an alumina substrate or the like. It is also formed to protect and insulate the varistor element body. Conventionally, a powder material paste has been used to form an insulating protective layer. This powder material paste is generally a mixture of glass powder and vehicle, and ceramic powder may be added as necessary.
　絶縁保護層は、粉末材料ペーストを電極等の上に塗布した後、焼成することにより形成される。ここで、焼成温度は、電極等と粉末材料の反応により、電極等の特性が劣化する事態を防止するために、８００℃以下に制限される。このため、粉末材料（粉末材料ペースト）には、８００℃以下の温度で焼成可能であることが要求される。また、粉末材料には、焼成後に、基板やバリスタ素体に反りを発生させず、基板やバリスタ素体から容易に剥離しないことも要求される。 The insulating protective layer is formed by applying a powder material paste on an electrode or the like and then baking it. Here, the firing temperature is limited to 800 ° C. or less in order to prevent a situation where the properties of the electrode and the like deteriorate due to the reaction between the electrode and the powder material. For this reason, the powder material (powder material paste) is required to be able to be fired at a temperature of 800 ° C. or lower. In addition, the powder material is required not to cause warping of the substrate or the varistor element body after firing and not to be easily peeled off from the substrate or varistor element body.
　上記の要求特性を満たす粉末材料として、従来まで、ＰｂＯ－Ｂ２Ｏ３－ＳｉＯ２系ガラスが使用されてきた（特許文献１参照）。 Conventionally, PbO—B 2 O 3 —SiO 2 -based glass has been used as a powder material that satisfies the above required characteristics (see Patent Document 1).
　近年、環境保護の観点から、環境負荷物質の削減、例えばＰｂＯの削減が推進されており、ＰｂＯ－Ｂ２Ｏ３－ＳｉＯ２系ガラスに代わって、各種無鉛ガラスが提案されるに到っている。例えば、特許文献２～４には、Ｂｉ２Ｏ３－Ｂ２Ｏ３－ＺｎＯ系ガラスが記載されている。 In recent years, from the viewpoint of environmental protection, reduction of environmentally hazardous substances, for example, PbO, has been promoted, and various lead-free glasses have been proposed in place of PbO—B 2 O 3 —SiO 2 based glass. Yes. For example, Patent Documents 2 to 4 describe Bi 2 O 3 —B 2 O 3 —ZnO-based glasses.
特開昭５８－６４２４５号公報JP 58-64245 A 特開２００９－２２１０２７号公報JP 2009-2221027 A 特開２００７－６３１０５号公報JP 2007-63105 A 特許第４５９８００８号公報Japanese Patent No. 4598008
　ところで、絶縁保護層が形成された電子回路には、防食性、光学特性、機械的特性、電気的特性等の特性を付与するために、メッキ処理が施される場合がある。このメッキ処理では、絶縁保護層がメッキ溶液に浸漬される。 By the way, the electronic circuit on which the insulating protective layer is formed may be subjected to a plating treatment in order to impart characteristics such as corrosion resistance, optical characteristics, mechanical characteristics, and electrical characteristics. In this plating process, the insulating protective layer is immersed in the plating solution.
　メッキ溶液は、通常、酸性溶液である。このため、メッキ処理が施される場合、絶縁保護層には、耐酸性が要求される。すなわち粉末材料には、耐酸性が要求される。 The plating solution is usually an acidic solution. For this reason, when plating is performed, the insulating protective layer is required to have acid resistance. That is, acid resistance is required for the powder material.
　しかしながら、特許文献２～４に記載のＢｉ２Ｏ３－Ｂ２Ｏ３－ＺｎＯ系ガラスは、耐酸性が低いため、メッキ溶液によって侵食され易く、絶縁性等の特性を維持し難いという問題を有している。 However, the Bi 2 O 3 —B 2 O 3 —ZnO-based glasses described in Patent Documents 2 to 4 have low acid resistance, so that they are easily eroded by the plating solution, and it is difficult to maintain characteristics such as insulation. Have.
　そこで、本発明は上記事情に鑑み成されたものであり、その技術的課題は、ＰｂＯを含まなくても、８００℃以下の温度で焼成可能であると共に、基板等の反りや基板等からの剥離が生じ難く、しかもメッキ溶液によって侵食され難いビスマス系ガラス組成物、粉末材料及び粉末材料ペーストを創案することである。 Therefore, the present invention has been made in view of the above circumstances, and its technical problem is that it can be fired at a temperature of 800 ° C. or less without containing PbO, and warps from the substrate or the like from the substrate or the like. It is to create a bismuth-based glass composition, a powder material, and a powder material paste that do not easily peel and are not easily eroded by a plating solution.
　本発明者は、種々の実験を行った結果、ガラス系としてビスマス系ガラスを採択すると共に、ガラス組成中のＳｉＯ２、ＺｒＯ２、Ａｌ２Ｏ３の含有割合を厳密に規制することにより、上記技術的課題を解決し得ることを見出し、本発明として提案するものである。すなわち、本発明のビスマス系ガラス組成物は、ガラス組成として、質量％で、Ｂｉ２Ｏ３　４０～５５％、ＳｉＯ２　２８～４０％、ＺｒＯ２　５超～９％、Ａｌ２Ｏ３　２～１０％、Ｂ２Ｏ３　０～５％を含有し、質量比（ＳｉＯ２＋ＺｒＯ２）／Ａｌ２Ｏ３が１５より小さいことを特徴とする。 As a result of various experiments, the present inventor adopted bismuth-based glass as a glass system and strictly controlled the content ratio of SiO 2 , ZrO 2 , and Al 2 O 3 in the glass composition, thereby The present inventors have found that technical problems can be solved and propose the present invention. That is, the bismuth-based glass composition of the present invention has a glass composition of Bi 2 O 3 40 to 55%, SiO 2 28 to 40%, ZrO 2 over 5 to 9%, Al 2 O 3 2 to 10%, B 2 O 3 0 to 5%, and the mass ratio (SiO 2 + ZrO 2 ) / Al 2 O 3 is smaller than 15.
　ビスマス系ガラスは、一般的に、耐酸性が低いが、本発明のビスマス系ガラス組成物では、ＳｉＯ２の含有量を２５質量％以上、且つ、ＺｒＯ２の含有量を５質量％超に規制することにより、耐酸性を高めている。一方、ＳｉＯ２の含有量が多い場合に、ＺｒＯ２の含有量が過剰になると、成形時に耐酸性を低下させるジルコン（ＺｒＳｉＯ４）結晶が析出して、所望の耐酸性を確保し難くなる場合がある。また成形時にガラスが分相して、所望の耐酸性を確保し難くなる場合もある。そこで、本発明のビスマス系ガラス組成物では、ガラス組成中のＡｌ２Ｏ３の含有量を２質量％以上、且つ質量比（ＳｉＯ２＋ＺｒＯ２）／Ａｌ２Ｏ３を１５未満に規制することにより、成形時のジルコン結晶の析出及びガラスの分相を抑制している。 Bismuth glass generally has low acid resistance. However, in the bismuth glass composition of the present invention, the content of SiO 2 is restricted to 25% by mass or more, and the content of ZrO 2 is restricted to more than 5% by mass. By doing so, acid resistance is improved. On the other hand, when the content of ZrO 2 is excessive when the content of SiO 2 is large, zircon (ZrSiO 4 ) crystals that reduce acid resistance during molding are precipitated, making it difficult to ensure desired acid resistance. There is. Further, the glass may be phase-divided during molding, and it may be difficult to ensure desired acid resistance. Therefore, in the bismuth-based glass composition of the present invention, the content of Al 2 O 3 in the glass composition is 2% by mass or more and the mass ratio (SiO 2 + ZrO 2 ) / Al 2 O 3 is regulated to less than 15. Thus, the precipitation of zircon crystals and the phase separation of glass during molding are suppressed.
　本発明のビスマス系ガラス組成物は、更にＢａＯを１～９質量％含むことが好ましい。 The bismuth-based glass composition of the present invention preferably further contains 1 to 9% by mass of BaO.
　本発明のビスマス系ガラス組成物は、ＭｇＯの含有量が５質量％以下、ＣａＯの含有量が５質量％以下、ＳｒＯの含有量が５質量％以下、且つＺｎＯの含有量が５質量％以下であることが好ましい。 In the bismuth-based glass composition of the present invention, the content of MgO is 5% by mass or less, the content of CaO is 5% by mass or less, the content of SrO is 5% by mass or less, and the content of ZnO is 5% by mass or less. It is preferable that
　本発明のビスマス系ガラス組成物は、実質的にＰｂＯを含まないことが好ましい。ここで、「実質的にＰｂＯを含まない」とは、不純物レベルでのＰｂＯの混入を許容するものの、積極的な導入を回避する趣旨であり、具体的にはガラス組成中のＰｂＯの含有量が１０００ｐｐｍ未満の場合を指す。 It is preferable that the bismuth-based glass composition of the present invention does not substantially contain PbO. Here, “substantially free of PbO” means that PbO is allowed to be mixed in at an impurity level, but avoids aggressive introduction. Specifically, the content of PbO in the glass composition Is less than 1000 ppm.
　本発明の粉末材料は、上記のビスマス系ガラス組成物からなるガラス粉末とセラミック粉末とを含有する粉末材料であって、ガラス粉末の含有量が５０～１００質量％、セラミック粉末の含有量が０～５０質量％であることを特徴とする。 The powder material of the present invention is a powder material containing a glass powder made of the bismuth-based glass composition and a ceramic powder, wherein the glass powder content is 50 to 100% by mass, and the ceramic powder content is 0. It is characterized by ˜50 mass%.
　本発明の粉末材料は、軟化点が８００℃以下であることが好ましい。ここで、「軟化点」は、マクロ型示差熱分析計（ＤＴＡ）で測定した第四の変曲点の温度を指す。 The powder material of the present invention preferably has a softening point of 800 ° C. or lower. Here, the “softening point” refers to the temperature at the fourth inflection point measured with a macro-type differential thermal analyzer (DTA).
　本発明の粉末材料は、絶縁保護層の形成に用いることが好ましい。 The powder material of the present invention is preferably used for forming an insulating protective layer.
　本発明の粉末材料ペーストは、粉末材料とビークルとを含有する粉末材料ペーストにおいて、粉末材料が上記に記載の粉末材料であることを特徴とする。 The powder material paste of the present invention is a powder material paste containing a powder material and a vehicle, wherein the powder material is the powder material described above.
　本発明のビスマス系ガラス組成物は、ガラス組成として、質量％で、Ｂｉ２Ｏ３　４０～５５％、ＳｉＯ２　２８～４０％、ＺｒＯ２　５超～９％、Ａｌ２Ｏ３　２～１０％、Ｂ２Ｏ３　０～５％を含有し、質量比ＳｉＯ２＋ＺｒＯ２／Ａｌ２Ｏ３が１５より小さいことを特徴とする。上記のように各成分の含有範囲を規制した理由を以下に説明する。なお、各成分の含有範囲の説明において、％表示は、質量％を意味する。 The bismuth-based glass composition of the present invention is, as a glass composition, by mass, Bi 2 O 3 40 to 55%, SiO 2 28 to 40%, ZrO 2 over 5 to 9%, Al 2 O 3 2 to 10%. , B 2 O 3 0 to 5%, and the mass ratio SiO 2 + ZrO 2 / Al 2 O 3 is smaller than 15. The reason why the content range of each component is regulated as described above will be described below. In addition, in description of the containing range of each component,% display means the mass%.
　Ｂｉ２Ｏ３は、軟化点を低下させる成分であるが、耐酸性を低下させる成分である。Ｂｉ２Ｏ３の含有量は４０～５５％であり、好ましくは４１～５４％、４２～５３％、特に４３～５２％である。Ｂｉ２Ｏ３の含有量が少なくなると、軟化点が不当に上昇して、８００℃以下の温度で焼成し難くなる。一方、Ｂｉ２Ｏ３の含有量が多くなると、耐酸性が低下し易くなり、メッキ溶液により、絶縁保護層が侵食され易くなり、結果として、電子回路の電極等を絶縁保護し難くなる。更に、Ｂｉ２Ｏ３の含有量が多くなると、原料コストが高騰し易くなる。 Bi 2 O 3 is a component that lowers the softening point, but is a component that lowers acid resistance. The content of Bi 2 O 3 is 40 to 55%, preferably 41 to 54%, 42 to 53%, particularly 43 to 52%. When the content of Bi 2 O 3 is reduced, the softening point is unduly raised and it becomes difficult to fire at a temperature of 800 ° C. or lower. On the other hand, when the content of Bi 2 O 3 increases, the acid resistance tends to decrease, and the insulating protective layer is easily eroded by the plating solution, and as a result, it becomes difficult to insulate and protect the electrodes of the electronic circuit. Furthermore, when the content of Bi 2 O 3 is increased, the raw material cost is likely to increase.
　ＳｉＯ２は、ガラス骨格を形成する成分であると共に、耐酸性を高める成分である。ＳｉＯ２の含有量は２８～４０％であり、好ましくは２９～３８％、特に３０～３６％である。ＳｉＯ２の含有量が少なくなると、耐酸性が低下し易くなり、メッキ溶液により、絶縁保護層が侵食され易くなり、結果として、電子回路の電極等を絶縁保護し難くなる。一方、ＳｉＯ２の含有量が多くなると、軟化点が不当に上昇して、８００℃以下の温度で焼成し難くなる。 SiO 2 is a component that forms a glass skeleton and a component that increases acid resistance. The content of SiO 2 is 28 to 40%, preferably 29 to 38%, in particular 30 to 36%. When the content of SiO 2 is reduced, the acid resistance is likely to be lowered, and the insulating protective layer is easily eroded by the plating solution. As a result, it is difficult to insulate and protect the electrodes of the electronic circuit. On the other hand, when the content of SiO 2 is increased, the softening point is unreasonably raised and it becomes difficult to fire at a temperature of 800 ° C. or lower.
　ＺｒＯ２は、耐酸性を高める成分である。ＺｒＯ２の含有量は５超～９％であり、好ましくは５．５～８．５％、特に６～８％である。ＺｒＯ２の含有量が少なくなると、耐酸性が低下し易くなり、メッキ溶液により、絶縁保護層が侵食され易くなり、結果として、電子回路の電極等を絶縁保護し難くなる。一方、ＺｒＯ２の含有量が多くなると、成形時にジルコン結晶が析出し易くなり、また軟化点が不当に上昇して、８００℃以下の温度で焼成し難くなる。 ZrO 2 is a component that increases acid resistance. The content of ZrO 2 is more than 5 to 9%, preferably 5.5 to 8.5%, particularly 6 to 8%. When the content of ZrO 2 decreases, the acid resistance tends to decrease, and the insulating protective layer is easily eroded by the plating solution. As a result, it becomes difficult to insulate and protect the electrodes of the electronic circuit. On the other hand, when the content of ZrO 2 is increased, zircon crystals are likely to precipitate during molding, and the softening point is unduly raised, making it difficult to fire at a temperature of 800 ° C. or lower.
　Ａｌ２Ｏ３は、耐酸性を高める成分であり、またガラスを安定化させる成分、特にジルコン結晶の析出を抑制する成分である。Ａｌ２Ｏ３の含有量は２～１０％であり、好ましくは２．５～９％、特に３～８％である。Ａｌ２Ｏ３の含有量が少なくなると、ガラスが不安定になって、成形時にジルコン結晶が析出し易くなる。一方、Ａｌ２Ｏ３の含有量が多くなると、軟化点が不当に上昇して、８００℃以下の温度で焼成し難くなる。 Al 2 O 3 is a component that enhances acid resistance and is a component that stabilizes glass, particularly a component that suppresses the precipitation of zircon crystals. The content of Al 2 O 3 is 2 to 10%, preferably 2.5 to 9%, particularly 3 to 8%. When the content of Al 2 O 3 is reduced, the glass becomes unstable and zircon crystals are likely to precipitate during molding. On the other hand, when the content of Al 2 O 3 is increased, the softening point is unreasonably raised and it becomes difficult to fire at a temperature of 800 ° C. or lower.
　Ｂ２Ｏ３は、ガラス骨格を形成し、ガラス化範囲を広げる成分であるが、その含有量が多くなると、耐酸性が大幅に低下する虞がある。よって、Ｂ２Ｏ３の含有量は０～５％であり、好ましくは０～４％、０～３％、特に０．５～２％である。 B 2 O 3 is a component that forms a glass skeleton and widens the vitrification range, but when its content increases, the acid resistance may be significantly reduced. Therefore, the content of B 2 O 3 is 0 to 5%, preferably 0 to 4%, 0 to 3%, particularly 0.5 to 2%.
　質量比（ＳｉＯ２＋ＺｒＯ２）／Ａｌ２Ｏ３が１５以下であり、好ましくは１４以下、１３以下、１２以下、１１以下、１０以下、特に９以下である。質量比（ＳｉＯ２＋ＺｒＯ２）／Ａｌ２Ｏ３が過大になると、成形時にジルコン結晶が析出し易くなったり、ガラスが分相し易くなる。 The mass ratio (SiO 2 + ZrO 2 ) / Al 2 O 3 is 15 or less, preferably 14 or less, 13 or less, 12 or less, 11 or less, 10 or less, particularly 9 or less. When the mass ratio (SiO 2 + ZrO 2 ) / Al 2 O 3 is excessive, zircon crystals are likely to precipitate during molding, and the glass is likely to be phase-separated.
　上記成分以外にも、例えば、以下の成分を導入してもよい。 In addition to the above components, for example, the following components may be introduced.
　ＭｇＯは、軟化点を低下させる成分であり、またガラスを安定化させる成分である。ＭｇＯの含有量は、好ましくは０～５％、０～４％、特に０～３％である。ＭｇＯの含有量が多くなると、耐酸性が低下し易くなり、メッキ溶液により、絶縁保護層が侵食され易くなり、結果として、電子回路の電極等を絶縁保護し難くなる。 MgO is a component that lowers the softening point and is a component that stabilizes the glass. The content of MgO is preferably 0 to 5%, 0 to 4%, particularly 0 to 3%. When the content of MgO increases, the acid resistance tends to decrease, and the insulating protective layer is easily eroded by the plating solution. As a result, it becomes difficult to insulate and protect the electrodes of the electronic circuit.
　ＣａＯは、軟化点を低下させる成分であり、またガラスを安定化させる成分である。ＣａＯの含有量は、好ましくは０～５％、０～４％、特に０～３％である。ＣａＯの含有量が多くなると、耐酸性が低下し易くなり、メッキ溶液により、絶縁保護層が侵食され易くなり、結果として、電子回路の電極等を絶縁保護し難くなる。 CaO is a component that lowers the softening point and is a component that stabilizes the glass. The content of CaO is preferably 0 to 5%, 0 to 4%, particularly 0 to 3%. When the content of CaO is increased, the acid resistance is likely to be lowered, and the insulating protective layer is easily eroded by the plating solution. As a result, it is difficult to insulate and protect the electrodes of the electronic circuit.
　ＳｒＯは、軟化点を低下させる成分であり、またガラスを安定化させる成分である。ＳｒＯの含有量は、好ましくは０～５％、０～４％、特に０～３％である。ＳｒＯの含有量が多くなると、耐酸性が低下し易くなり、メッキ溶液により、絶縁保護層が侵食され易くなり、結果として、電子回路の電極等を絶縁保護し難くなる。 SrO is a component that lowers the softening point and is a component that stabilizes the glass. The SrO content is preferably 0 to 5%, 0 to 4%, in particular 0 to 3%. When the SrO content increases, the acid resistance tends to decrease, and the insulating protective layer is easily eroded by the plating solution. As a result, it becomes difficult to insulate and protect the electrodes of the electronic circuit.
　ＢａＯは、軟化点を低下させる成分であり、またガラスを安定化させる成分、特に分相を抑制する成分である。ＢａＯの含有量は、好ましくは０～９％、１～９％、２～８％、特に３～７％である。ＢａＯの含有量が少なくなると、ガラスが不安定になり易い。一方、ＢａＯの含有量が多くなると、耐酸性が低下し易くなり、メッキ溶液により、絶縁保護層が侵食され易くなり、結果として、電子回路の電極等を絶縁保護し難くなる。 BaO is a component that lowers the softening point and is a component that stabilizes the glass, particularly a component that suppresses phase separation. The content of BaO is preferably 0-9%, 1-9%, 2-8%, in particular 3-7%. When the content of BaO decreases, the glass tends to become unstable. On the other hand, when the content of BaO increases, the acid resistance tends to decrease, and the insulating protective layer is easily eroded by the plating solution, and as a result, it becomes difficult to insulate and protect the electrodes of the electronic circuit.
　ＺｎＯは、軟化点を低下させる成分であるが、耐酸性を低下させる成分である。ＺｎＯの含有量は０～５％であり、好ましくは０～４％、特に０～３％である。ＺｎＯの含有量が多くなると、耐酸性が大幅に低下し、メッキ溶液により、絶縁保護層が侵食され易くなり、結果として、電子回路の電極等を絶縁保護し難くなる。 ZnO is a component that lowers the softening point but is a component that reduces acid resistance. The content of ZnO is 0 to 5%, preferably 0 to 4%, particularly 0 to 3%. When the content of ZnO is increased, the acid resistance is significantly reduced, and the insulating protective layer is easily eroded by the plating solution, and as a result, it becomes difficult to insulate and protect the electrodes of the electronic circuit.
　上記成分以外にも、要求特性を損なわない範囲で種々の成分を導入してもよい。例えば、軟化点を低下させるために、Ｃｓ２Ｏ、Ｒｂ２Ｏ等を合量又は単独で５％まで、特に１％まで導入してもよい。またガラスを安定化させたり、耐水性や耐酸性を高めるために、Ｙ２Ｏ３、Ｌａ２Ｏ３、Ｔａ２Ｏ５、ＳｎＯ２、ＴｉＯ２、Ｎｂ２Ｏ５、Ｐ２Ｏ５、ＣｕＯ、ＣｅＯ２、Ｖ２Ｏ５等を合量又は単独で１０％まで、特に１％まで導入してもよい。 In addition to the above components, various components may be introduced as long as the required characteristics are not impaired. For example, in order to lower the softening point, Cs 2 O, Rb 2 O, or the like may be introduced up to 5%, particularly up to 1%, alone or in total. Moreover, in order to stabilize glass and to improve water resistance and acid resistance, Y 2 O 3 , La 2 O 3 , Ta 2 O 5 , SnO 2 , TiO 2 , Nb 2 O 5 , P 2 O 5 , CuO , CeO 2 , V 2 O 5, etc. may be introduced in a total amount or independently up to 10%, particularly up to 1%.
　ＰｂＯは、軟化点を低下させる成分であるが、環境負荷物質でもあるため、実質的な導入を回避することが好ましい。 PbO is a component that lowers the softening point, but it is also an environmentally hazardous substance, so it is preferable to avoid substantial introduction.
　本発明の粉末材料は、上記のビスマス系ガラス組成物からなるガラス粉末とセラミック粉末とを含有する粉末材料であって、ガラス粉末の含有量が５０～１００質量％、セラミック粉末の含有量が０～５０質量％であることを特徴とする。 The powder material of the present invention is a powder material containing a glass powder made of the bismuth-based glass composition and a ceramic powder, wherein the glass powder content is 50 to 100% by mass, and the ceramic powder content is 0. It is characterized by ˜50 mass%.
　ガラス粉末は、例えば、溶融ガラスをフィルム状に成形した後、得られたガラスフィルムを粉砕、分級することにより作製することができる。 The glass powder can be produced, for example, by forming molten glass into a film and then crushing and classifying the obtained glass film.
　ガラス粉末の平均粒径Ｄ５０は３．０μｍ以下が好ましく、最大粒径Ｄｍａｘは２０μｍ以下が好ましい。ガラス粉末の粒度が大き過ぎると、絶縁保護層中に大きな泡が残存し易くなる。ここで、「平均粒径Ｄ５０」とは、レーザー回折装置で測定した値を指し、レーザー回折法により測定した際の体積基準の累積粒度分布曲線において、その積算量が粒子の小さい方から累積して５０％である粒子径を表す。また「最大粒径Ｄｍａｘ」とは、レーザー回折装置で測定した値を指し、レーザー回折法により測定した際の体積基準の累積粒度分布曲線において、その積算量が粒子の小さい方から累積して９９％である粒子径を表す。 The average particle diameter D 50 of the glass powder is preferably 3.0 μm or less, and the maximum particle diameter D max is preferably 20 μm or less. When the particle size of the glass powder is too large, large bubbles are likely to remain in the insulating protective layer. Here, the “average particle diameter D 50 ” refers to a value measured with a laser diffractometer, and in an accumulated particle size distribution curve based on volume when measured by a laser diffraction method, the accumulated amount is accumulated from the smaller particle. The particle diameter is 50%. “Maximum particle size D max ” refers to a value measured by a laser diffractometer, and in the volume-based cumulative particle size distribution curve measured by the laser diffraction method, the accumulated amount is accumulated from the smaller particle. The particle size is 99%.
　セラミック粉末の含有量は、好ましくは４０質量％以下、３０質量％以下、２０質量％以下、１０質量％以下、５質量％以下、特に１質量％未満である。セラミック粉末が多過ぎると、相対的にガラス粉末の割合が少なくなり過ぎて、緻密な絶縁保護層を形成し難くなるため、メッキ溶液により、絶縁保護層が侵食され易くなり、結果として、電子回路の電極等を絶縁保護し難くなる。なお、セラミック粉末を添加すると、粉末材料の熱膨張係数、機械的強度、耐酸性を調整することが可能になる。 The content of the ceramic powder is preferably 40% by mass or less, 30% by mass or less, 20% by mass or less, 10% by mass or less, 5% by mass or less, and particularly less than 1% by mass. If the ceramic powder is too much, the proportion of the glass powder becomes relatively small, and it becomes difficult to form a dense insulating protective layer, so that the insulating protective layer is easily eroded by the plating solution. It becomes difficult to insulate and protect the electrodes. If ceramic powder is added, the thermal expansion coefficient, mechanical strength, and acid resistance of the powder material can be adjusted.
　セラミック粉末として、種々の材料が使用可能であり、例えば、アルミナ、ジルコニア、ムライト、シリカ、コーディエライト、チタニア、酸化スズ等を一種又は二種以上添加することができる。 Various materials can be used as the ceramic powder. For example, one or more of alumina, zirconia, mullite, silica, cordierite, titania, tin oxide, and the like can be added.
　本発明の粉末材料において、軟化点は、好ましくは８００℃以下、７９０℃以下、特に６８０～７８０℃である。軟化点が高過ぎると、緻密な絶縁保護層を得るためには、焼成温度を上昇しなければならず、その場合、電極等と粉末材料が反応して、電極等の特性が劣化し易くなる。 In the powder material of the present invention, the softening point is preferably 800 ° C. or lower, 790 ° C. or lower, particularly 680 to 780 ° C. If the softening point is too high, in order to obtain a dense insulating protective layer, the firing temperature must be increased, in which case the electrode and the powder material react and the characteristics of the electrode and the like are likely to deteriorate. .
　本発明の粉末材料において、熱膨張係数は、４５～６５×１０－７／℃、特に５０～６０×１０－７／℃が好ましい。このようにすれば、絶縁保護層を形成した後に、基板等の反りや絶縁保護層の剥離を防止し易くなる。ここで、「熱膨張係数」は、熱機械分析装置（ＴＭＡ）により３０～３００℃の温度範囲で測定した値である。 In the powder material of the present invention, the thermal expansion coefficient is preferably 45 to 65 × 10 −7 / ° C., particularly 50 to 60 × 10 −7 / ° C. If it does in this way, it will become easy to prevent the curvature of a board | substrate etc. and peeling of an insulating protective layer after forming an insulating protective layer. Here, the “thermal expansion coefficient” is a value measured in a temperature range of 30 to 300 ° C. by a thermomechanical analyzer (TMA).
　本発明の粉末材料ペーストは、粉末材料とビークルとを含有する粉末材料ペーストにおいて、粉末材料が上記の粉末材料であることを特徴とする。ここで、ビークルは、ガラス粉末を分散させて、ペースト化するための材料であり、通常、熱可塑性樹脂、可塑剤、溶剤等により構成される。 The powder material paste of the present invention is a powder material paste containing a powder material and a vehicle, wherein the powder material is the powder material described above. Here, the vehicle is a material for dispersing glass powder into a paste, and is usually composed of a thermoplastic resin, a plasticizer, a solvent, and the like.
　粉末材料ペーストは、粉末材料とビークルを用意し、これらを所定の割合で混合、混練することにより作製することができる。 The powder material paste can be prepared by preparing a powder material and a vehicle, and mixing and kneading them at a predetermined ratio.
　熱可塑性樹脂は、乾燥後の膜強度を高める成分であり、また柔軟性を付与する成分である。粉末材料ペースト中の熱可塑性樹脂の含有量は０．１～２０質量％が好ましい。熱可塑性樹脂として、ポリブチルメタアクリレート、ポリビニルブチラール、ポリメチルメタアクリレート、ポリエチルメタアクリレート、エチルセルロース等が好ましく、これらの内、一種又は二種以上を用いることが好ましい。 Thermoplastic resin is a component that increases the film strength after drying and also a component that imparts flexibility. The content of the thermoplastic resin in the powder material paste is preferably 0.1 to 20% by mass. As the thermoplastic resin, polybutyl methacrylate, polyvinyl butyral, polymethyl methacrylate, polyethyl methacrylate, ethyl cellulose and the like are preferable, and it is preferable to use one or more of these.
　溶剤は、熱可塑性樹脂を溶解させるための成分である。粉末材料ペースト中の溶剤の含有量は１０～３０質量％が好ましい。溶剤として、ターピネオール、ジエチレングリコールモノブチルエーテルアセテート、２，２，４－トリメチル－１，３－ペンタジオールモノイソブチレート等が好ましく、これらの内、一種又は二種以上を用いることが好ましい。 Solvent is a component for dissolving the thermoplastic resin. The content of the solvent in the powder material paste is preferably 10 to 30% by mass. As the solvent, terpineol, diethylene glycol monobutyl ether acetate, 2,2,4-trimethyl-1,3-pentadiol monoisobutyrate and the like are preferable, and it is preferable to use one or more of these.
　粉末材料ペーストを用いて、電子回路に絶縁保護層を形成するには、まず電極、抵抗体等が形成された電子回路上に、スクリーン印刷法、一括コート法等により粉末材料ペーストを塗布し、所定の膜厚の塗布層を形成した後、乾燥させて、乾燥膜を得る。その後、乾燥膜を７００～８００℃の温度で５～２０分間焼成することにより、所定の絶縁保護層（焼成膜）を形成することができる。なお、焼成温度が低過ぎたり、焼成時間（保持時間）が短過ぎると、乾燥膜が十分に焼結せず、緻密な焼成膜を形成し難くなる。一方、焼成温度が高過ぎたり、保持時間が長過ぎると、電極等と粉末材料が反応して、電極等の特性が劣化し易くなる。 In order to form an insulating protective layer in an electronic circuit using a powder material paste, first, a powder material paste is applied on an electronic circuit on which electrodes, resistors, etc. are formed by a screen printing method, a batch coating method, After forming a coating layer having a predetermined thickness, it is dried to obtain a dry film. Thereafter, the predetermined insulating protective layer (baked film) can be formed by baking the dried film at a temperature of 700 to 800 ° C. for 5 to 20 minutes. If the firing temperature is too low or the firing time (holding time) is too short, the dried film will not sinter sufficiently, 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 electrode and the powder material react with each other, and the characteristics of the electrode and the like easily deteriorate.
　絶縁保護層の形成方法として、粉末材料ペーストを用いる方法を例にして説明したが、それ以外の方法を採択することもできる。例えば、グリーンシート法、感光性ペースト法、感光性グリーンシート法等の方法を採択してもよい。 As the method for forming the insulating protective layer, the method using a powder material paste has been described as an example, but other methods may be adopted. For example, a method such as a green sheet method, a photosensitive paste method, or a photosensitive green sheet method may be adopted.
　本発明のビスマス系ガラス組成物、粉末材料及び粉末材料ペーストは、絶縁保護層の形成に用いることが好ましく、特にバリスタ素体上の絶縁保護層の形成に用いることが好ましい。バリスタ素体では、ＺｎＯ酸化物からなるバリスタ素体に電極、抵抗体等が形成されると共に、その上に絶縁保護層が形成される。その後、メッキ溶液によるメッキ処理が施される。上記のように、本発明のビスマス系ガラス組成物、粉末材料及び粉末材料ペーストは、ＰｂＯを含まなくても、８００℃以下の温度で焼成可能であると共に、バリスタ素体の反りやバリスタ素体からの剥離が生じ難く、しかもメッキ溶液によって侵食され難いため、本用途に特に好適である。 The bismuth-based glass composition, powder material and powder material paste of the present invention are preferably used for forming an insulating protective layer, and particularly preferably used for forming an insulating protective layer on a varistor element body. In the varistor element body, electrodes, resistors, and the like are formed on the varistor element body made of ZnO oxide, and an insulating protective layer is formed thereon. Thereafter, a plating treatment with a plating solution is performed. As described above, the bismuth-based glass composition, the powder material, and the powder material paste of the present invention can be fired at a temperature of 800 ° C. or less without containing PbO, and warp of the varistor element body and the varistor element body. It is particularly suitable for this application because it does not easily peel off from the film and is not easily eroded by the plating solution.
　以下、実施例に基づいて、本発明を詳細に説明する。なお、本発明は以下の実施例に何ら限定されない。以下の実施例は単なる例示である。 Hereinafter, the present invention will be described in detail based on examples. The present invention is not limited to the following examples. The following examples are merely illustrative.
　表１は、本発明の実施例（試料Ｎｏ．１～４）及び比較例（試料Ｎｏ．５、６）を示している。 Table 1 shows examples (samples Nos. 1 to 4) and comparative examples (samples Nos. 5 and 6) of the present invention.
Figure JPOXMLDOC01-appb-T000001
Figure JPOXMLDOC01-appb-T000001
　次のようにして、各試料を調製した。まず表中に示すガラス組成になるように、原料を調合して、均一に混合した。次いで、白金ルツボに入れて１３５０～１４５０℃で２時間溶融した後、フィルム状に成形した。 Each sample was prepared as follows. First, raw materials were prepared and mixed uniformly so as to have the glass composition shown in the table. Next, it was put in a platinum crucible and melted at 1350 to 1450 ° C. for 2 hours, and then formed into a film.
　得られたガラスフィルムをついて、成形性を評価した。ガラスフィルムの表面に失透結晶（ブツ）が認められず、分相も認められなかったものを「○」、失透結晶及び／又は分相が僅かに認められたものを「△」、失透結晶及び／又は分相が顕著に認められたものを「×」として評価した。 The moldability was evaluated using the obtained glass film. “O” indicates that no devitrification crystals (bumps) are observed on the surface of the glass film and no phase separation is observed, and “△” indicates that devitrification crystals and / or phase separation is slightly observed. A sample in which a permeable crystal and / or phase separation was remarkably recognized was evaluated as “x”.
　続いて、上記のガラスフィルムをボールミルにて粉砕した後、気流分級して平均粒径Ｄ５０３．０μｍ以下、最大粒径Ｄｍａｘ２０μｍ以下のガラス粉末を得た。得られたガラス粉末を用いて、軟化点及び熱膨張係数を評価した。 Subsequently, the above glass film was pulverized with a ball mill and then classified into an air stream to obtain a glass powder having an average particle size D 50 of 3.0 μm or less and a maximum particle size D max of 20 μm or less. The softening point and thermal expansion coefficient were evaluated using the obtained glass powder.
　軟化点は、マクロ型示差熱分析計（ＤＴＡ）で測定した第四の変曲点の温度である。 Softening point is the temperature of the fourth inflection point measured with a macro-type differential thermal analyzer (DTA).
　熱膨張係数は、各ガラス粉末を加圧形成し、（軟化点＋１０）℃で焼成した後、直径５ｍｍ、長さ２０ｍｍに加工して、測定試料を得た上で、熱機械分析装置（ＴＭＡ）により３０～３００℃の温度範囲で測定した値である。 The coefficient of thermal expansion was determined by pressing each glass powder and firing it at (softening point +10) ° C., then processing to a diameter of 5 mm and a length of 20 mm to obtain a measurement sample, and then a thermomechanical analyzer (TMA) ) Measured in a temperature range of 30 to 300 ° C.
　次に、上記ガラス粉末とビークル（エチルセルロースを５質量％、且つアセチルクエン酸トリブチルを３質量％含むターピネオール）を混合し、３本ロールミルにて混練して、粉末材料ペーストを得た。更に、約１０μｍの焼成膜（絶縁保護層）が得られるように、粉末材料ペーストをアルミナ基板上にスクリーン印刷法で塗布した後、塗布膜を乾燥し、電気炉で（軟化点＋１０）℃の温度で１０分間焼成した。得られた焼成膜付き基板を用いて、耐酸性を評価した。具体的には、焼成膜付き基板を４０℃の５質量％硫酸に５時間浸漬した上で、水洗、乾燥した後、質量減少を測定し、浸漬前後の質量減少の割合を評価した。なお、質量減少の割合が大きい程、耐酸性が低いことを意味する。 Next, the glass powder and the vehicle (terpineol containing 5% by mass of ethyl cellulose and 3% by mass of tributyl acetylcitrate) were mixed and kneaded in a three-roll mill to obtain a powder material paste. Further, after applying the powder material paste on the alumina substrate by screen printing so that a fired film (insulating protective layer) of about 10 μm can be obtained, the coated film is dried, and the temperature is (softening point + 10) ° C. in an electric furnace. Bake for 10 minutes at temperature. Acid resistance was evaluated using the obtained substrate with a fired film. Specifically, the substrate with the fired film was immersed in 5% by mass sulfuric acid at 40 ° C. for 5 hours, washed with water, dried, then measured for mass decrease, and evaluated the rate of mass decrease before and after immersion. In addition, it means that acid resistance is so low that the ratio of mass reduction is large.
　表１から明らかなように、試料Ｎｏ．１～４は、軟化点が低いため８００℃以下の温度で焼成可能であり、更に成形性や耐酸性が良好であった。試料Ｎｏ．５は、軟化点が低かったが、分相傾向が僅かに認められた。結果として、成形性や耐酸性が低かった。試料Ｎｏ．６は、成形性や耐酸性が不良であった。 As is clear from Table 1, sample No. Nos. 1 to 4 could be fired at a temperature of 800 ° C. or lower due to their low softening point, and further had good moldability and acid resistance. Sample No. No. 5 had a low softening point, but a slight phase separation tendency was observed. As a result, moldability and acid resistance were low. Sample No. No. 6 had poor moldability and acid resistance.
　本発明のビスマス系ガラス組成物、粉末材料及び粉末材料ペーストは、バリスタ素体、電子回路上の絶縁保護層の形成に好適であるが、それ以外にも、例えば、電子部品材料用バインダ、封着用材料等の用途に適用することもできる。 The bismuth-based glass composition, powder material, and powder material paste of the present invention are suitable for forming an insulating protective layer on a varistor element body and an electronic circuit. It can also be applied to uses such as wearing materials.

Claims (8)

  1. 　ガラス組成として、質量％で、Ｂｉ２Ｏ３　４０～５５％、ＳｉＯ２　２８～４０％、ＺｒＯ２　５超～９％、Ａｌ２Ｏ３　２～１０％、Ｂ２Ｏ３　０～５％を含有し、質量比（ＳｉＯ２＋ＺｒＯ２）／Ａｌ２Ｏ３が１５より小さいことを特徴とするビスマス系ガラス組成物。 As a glass composition, Bi 2 O 3 40 to 55%, SiO 2 28 to 40%, ZrO 2 over 5 to 9%, Al 2 O 3 2 to 10%, B 2 O 3 0 to 5% by mass% A bismuth-based glass composition comprising: a mass ratio (SiO 2 + ZrO 2 ) / Al 2 O 3 of less than 15.
  2. 　更にＢａＯを１～９質量％含むことを特徴とする請求項１に記載のビスマス系ガラス組成物。 The bismuth-based glass composition according to claim 1, further comprising 1 to 9% by mass of BaO.
  3. 　ＭｇＯの含有量が５質量％以下、ＣａＯの含有量が５質量％以下、ＳｒＯの含有量が５質量％以下、且つＺｎＯの含有量が５質量％以下であることを特徴とする請求項１又は２に記載のビスマス系ガラス組成物。 The MgO content is 5% by mass or less, the CaO content is 5% by mass or less, the SrO content is 5% by mass or less, and the ZnO content is 5% by mass or less. Or the bismuth-type glass composition of 2.
  4. 　実質的にＰｂＯを含まないことを特徴とする請求項１～３の何れかに記載のビスマス系ガラス組成物。 The bismuth-based glass composition according to any one of claims 1 to 3, which is substantially free of PbO.
  5. 　請求項１～４の何れかに記載のビスマス系ガラス組成物からなるガラス粉末とセラミック粉末とを含有する粉末材料であって、
    　ガラス粉末の含有量が５０～１００質量％、セラミック粉末の含有量が０～５０質量％であることを特徴とする粉末材料。     A powder material comprising a glass powder and a ceramic powder comprising the bismuth-based glass composition according to any one of claims 1 to 4,
    A powder material having a glass powder content of 50 to 100% by mass and a ceramic powder content of 0 to 50% by mass.
  6. 　軟化点が８００℃以下であることを特徴とする請求項５に記載の粉末材料。 The powder material according to claim 5, wherein the softening point is 800 ° C or lower.
  7. 　絶縁保護層の形成に用いることを特徴とする請求項５又は６に記載の粉末材料。 The powder material according to claim 5 or 6, which is used for forming an insulating protective layer.
  8. 　粉末材料とビークルとを含有する粉末材料ペーストにおいて、
    　粉末材料が請求項５～７の何れかに記載の粉末材料であることを特徴とする粉末材料ペースト。     In a powder material paste containing a powder material and a vehicle,
    A powder material paste, wherein the powder material is the powder material according to any one of claims 5 to 7.
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JPS6114151A (en) * 1984-06-28 1986-01-22 オーエンス‐イリノイ・インコーポレーテツド Chemical-resistant lead-free glass frit composition
JPH05262536A (en) * 1991-06-14 1993-10-12 Cookson Group Plc Glass flux composition

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