JP2012054113A - Copper paste composition and ceramic structure - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper paste composition, which allows the formation of metalization wiring with good adhesion on a ceramic substrate.SOLUTION: The copper paste composition includes at least copper powder, non-lead glass frit and copper oxide (I). The copper powder includes first copper particles and second copper particles, which are different from each other in softening start temperature. If the softening start temperature of the first copper particles is represented by T1(°C), and the softening start temperature of the second copper particles is represented by T2(°C), the value of T1-T2 is equal to or higher than 200°C. The non-lead glass frit at least includes bismuth, boron and silicon oxides, and has a softening start temperature equal to or lower than 400°C.

Description

  The present invention relates to a copper paste composition suitable for forming a metallized wiring or the like of a ceramic wiring board and a ceramic structure obtained by applying a copper paste composition to a ceramic sintered body and firing it.

  The metallized wiring of the ceramic wiring board is usually formed of a metal paste composition. The metal paste composition contains metal powder and glass frit, and is obtained by adding and kneading a resin binder and a solvent thereto.

  As the metal powder, copper powder that is excellent in electrical conductivity and thermal conductivity and inexpensive is often used (for example, see Patent Document 1). Glass frit improves the adhesion of the metallized wiring to the ceramic substrate. Conventionally, glass containing frit has been used, but lead is harmful. Replacement with lead glass frit is progressing.

Here, in the case of forming a metallized wiring by printing and applying a copper paste composition to a ceramic substrate and firing, firing is performed in a non-oxygen atmosphere in order to prevent copper from being oxidized and lowering its conductivity. To do.
However, when a copper paste composition containing non-lead glass frit is fired in a non-oxygen atmosphere, there is a problem that it is difficult to obtain adhesion between the metallized wiring and the ceramic substrate.

Japanese Patent Laid-Open No. 2-106808

  An object of the present invention is to provide a copper paste composition capable of forming a metallized wiring having excellent adhesion to a ceramic substrate.

As a result of intensive studies to solve the above problems, the present inventor has found a solution means having the following configuration, and has completed the present invention.
(1) A copper paste composition containing at least a copper powder, a lead-free glass frit and copper (I) oxide, wherein the copper powder has a plurality of first copper particles and a second plurality of copper particles having different softening start temperatures. When a plurality of copper particles are included, a softening start temperature of the first plurality of copper particles is T1 (° C.), and a softening start temperature of the second plurality of copper particles is T2 (° C.), T1 -T2 value is 200 ° C or higher, and the non-lead glass frit contains at least each oxide of bismuth, boron and silicon, and has a softening start temperature of 400 ° C or lower. .
(2) When the average particle diameter of the first plurality of copper particles is D1 (μm) and the average particle diameter of the second plurality of copper particles is D2 (μm), the value of D1-D2 is 1. The copper paste composition according to (1), which is 8 μm or more.
(3) The copper paste composition according to (1) or (2), wherein the non-lead glass frit further includes oxides of zirconium, chromium, aluminum, zinc, and sodium.
(4) The copper paste composition according to any one of (1) to (3), further including a resin binder including an acrylic resin and a nitrocellulose resin.
(5) The acrylic resin has glass transition temperatures different from each other, and both the H component and the L component made of (meth) acrylic acid ester are in a ratio such that the total molar fraction of both components is 80 mol% or more. When the glass transition temperature of the homopolymer in the H component is Tgh (° C.) and the glass transition temperature of the homopolymer in the L component is Tgl (° C.), the Tgh is 100 ° C. or higher. And the value of Tgh-Tgl is 50 ° C. or more, and the copolymer contains at least one selected from hydroxyl group-containing (meth) acrylic acid ester and polyalkylene oxide chain-containing (meth) acrylic acid ester. The copper paste composition according to (4), wherein a polar functional group-containing (meth) acrylic acid ester is further copolymerized.
(6) The copper paste composition according to any one of (1) to (5), further including a thixotropic agent.
(7) The copper paste composition according to (6), wherein the thixotropic agent includes hydrogenated castor oil and amide wax.
(8) The copper paste composition according to any one of (1) to (7), which is for postfire.
(9) The copper paste composition according to any one of (1) to (8), which is fired at a maximum temperature of 900 to 1000 ° C. in a non-oxygen atmosphere.
(10) A ceramic structure obtained by applying the copper paste composition according to any one of (1) to (9) to a ceramic sintered body and firing it.
(11) The ceramic structure according to (10), which is a multi-piece ceramic wiring board.

  According to the present invention, there is an effect that a metallized wiring having excellent adhesion to a ceramic substrate can be formed even when fired in a non-oxygen atmosphere. In addition, since the lead-free glass frit is used, adverse effects on the environment and the human body can be reduced.

  The copper paste composition of the present invention contains at least copper powder, non-lead glass frit, and copper (I) oxide. The copper powder includes a plurality of first plurality of copper particles and a plurality of second plurality of copper particles, each having a different softening start temperature.

  Specifically, the softening start temperature of the first plurality of copper particles is higher than the softening start temperature of the second plurality of copper particles, and the softening start temperature of the first plurality of copper particles is T1 (° C.), When the softening start temperature of the second plurality of copper particles is T2 (° C.), the value of T1-T2 is 200 ° C. or higher, preferably 200 to 300 ° C., more preferably 200 to 250 ° C. Thereby, a metallized wiring having excellent adhesion to the ceramic substrate can be formed. The reason for this is presumed as follows.

  That is, when the softening start temperature of the copper powder is lowered, the fluidity at the time of firing is improved and adhesion to the ceramic substrate is easily obtained, but the strength of the metallized wiring is lowered. Electronic components such as LEDs cannot be mounted with high reliability using low-strength metallized wiring. On the other hand, if the softening start temperature of the copper powder is increased, strength can be imparted to the metallized wiring, but the fluidity during firing is reduced and adhesion to the ceramic substrate is difficult to obtain. When the first plurality of copper particles having a high softening start temperature and the second plurality of copper particles having a low softening start temperature are included in the copper powder, and the temperature difference between the two is 200 ° C. or more, the first plurality The copper particles can provide strength to the metallized wiring, and the second plurality of copper particles can provide adhesion to the ceramic substrate, and as a result, excellent adhesion to the ceramic substrate while maintaining strength. Is formed.

As T1, it is preferable that it is 500-600 degreeC, and it is more preferable that it is 530-570 degreeC. As T2, it is preferable that it is 270-370 degreeC, and it is more preferable that it is 300-340 degreeC. T1 and T2 are obtained by changing the average particle diameter of each of the first and second plurality of copper particles or the reaction conditions, the reducing agent, the deoxidizing material, etc. during the production of the first and second plurality of copper particles. It can be adjusted arbitrarily. In the present embodiment, the softening start temperature of a plurality of copper particles is a value measured by TMA (Thermomechanical Analysis), and a constant load is applied to a measurement tablet made of a plurality of copper particles. It is the thermal shrinkage start temperature measured by this. TMA is performed, for example, by applying a certain load to the measurement tablet while raising the temperature in a reducing atmosphere or an atmosphere of nitrogen gas of 150 ml / min. The temperature rising rate in TMA is, for example, 10 ° C./min. The tablet for measurement is formed into a cylindrical shape having a diameter of 5 mm and a height of 10 mm, for example, by pressing a mixture containing a plurality of copper particles and wax at 10 ton / cm ² .

  Moreover, it is preferable that the first plurality of copper particles and the second plurality of copper particles have different average particle diameters. Specifically, it is preferable that the average particle diameter of the first plurality of copper particles is larger than the average particle diameter of the second plurality of copper particles. Thereby, intensity | strength can be provided to metallization wiring by the 1st some copper particle with a high softening start temperature and a large average particle diameter. In addition, the second plurality of copper particles having a low softening start temperature and a small average particle diameter are filled with no gap between the first plurality of copper particles, and are melted in this state. Metallized wiring can be formed.

  More specifically, when the average particle diameter of the first plurality of copper particles is larger than the average particle diameter of the second plurality of copper particles, the second plurality of copper particles around the first plurality of copper particles. As a result, it becomes easier to obtain the effect of including the first and second copper particles described above, and the bulk strength of the metallized wiring is improved. Further, the first and second plurality of copper particles can easily form a close-packed structure, thereby reducing the resistance of the metallized wiring and suppressing the generation of voids. Thereby, the effect which suppresses the fall of the adhesion resulting from the plating chemical | medical agent in the metal-plating wiring invading into a metallizing wiring mentioned later, and chemically attacking the glass to contain can also be anticipated.

  In particular, when the average particle diameter of the first plurality of copper particles is D1 (μm) and the average particle diameter of the second plurality of copper particles is D2 (μm), the value of D1-D2 is 1.8 μm or more. It is preferable that it is 1.8 to 2.0 μm. Thereby, the effect by making the average particle diameter of the 1st, 2nd some copper particle mentioned above different from each other can be improved more.

  The average particle diameter of the first plurality of copper particles is preferably 2 to 5 μm, and more preferably 2 to 3 μm. The average particle diameter of the second plurality of copper particles is preferably 0.1 to 1 μm, and more preferably 0.1 to 0.7 μm.

  The ratio of the first plurality of copper particles is preferably greater than the ratio of the second plurality of copper particles. Specifically, by mass ratio, the first plurality of copper particles: the second plurality of copper particles is preferably 9: 1 to 6: 4, and more preferably 9: 1 to 7: 3. preferable. Accordingly, the second plurality of copper particles are likely to be present around the first plurality of copper particles, and as a result, the effect of including the first and second plurality of copper particles is easily obtained. Become.

On the other hand, the lead-free glass frit contains at least each oxide (Bi ₂ O ₃ , B ₂ O ₃ , SiO ₂ ) of bismuth (Bi), boron (B), and silicon (Si). Bismuth (Bi ₂ O ₃ —B ₂ O ₃ —SiO ₂ ) -based glass. Bi ₂ O ₃ , B ₂ O ₃ , and SiO ₂ are all glass skeletons. In particular, Bi ₂ O ₃ has the effect of lowering the glass softening start temperature and the effect of improving the adhesion to the ceramic substrate. B ₂ O ₃ has the effect of lowering the softening start temperature of the glass and the effect of stabilizing the glass. SiO ₂ has the effect of improving the chemical resistance and water resistance of the glass against plating agents and the like.

Lead-free glass frit, in terms of oxide, the Bi ₂ O ₃ 50 to 94 wt%, the B ₂ O ₃ 5 to 30 wt%, a SiO ₂ 1 to 50% by weight, that a proportion of the preferred. This ratio is a value obtained by measurement by XRF (fluorescent X-ray analysis) and ICP (Inductively Coupled Plasma) analysis.

Further, the lead-free glass frit includes zirconium (Zr), chromium (Cr), aluminum (Al), zinc (Zn), and sodium (Na) oxides (ZrO ₂ , Cr ₂ O ₃ , Al ₂ O ₃ , It is preferable to further contain ZnO, Na ₂ O). Of these oxides, ZrO ₂ and Al ₂ O ₃ have the effect of improving chemical resistance. Cr ₂ O ₃ , ZnO and Na ₂ O have the effect of improving the adhesion to the ceramic substrate. Therefore, when the lead-free glass frit further contains these oxides, the adhesion and chemical resistance of the metallized wiring to the ceramic substrate are improved.

When the lead-free glass frit further contains ZrO ₂ , Cr ₂ O ₃ , Al ₂ O ₃ , ZnO, and Na ₂ O, the lead-free glass frit contains 50 to 93. Bi ₂ O ₃ in terms of oxide. 1 wt%, the B ₂ O ₃ 5 to 30 wt%, the SiO ₂ comprises in a proportion of 1 to 50 mass%, further ZrO ₂ 0.1 to 10 wt%, the Cr ₂ O ₃ 0.1 to 3 It is preferable to contain 0.1% by mass to 10% by mass of Al ₂ O ₃ , 0.1 to 10% by mass of ZnO, and 0.5 to 10% by mass of Na ₂ O.

As the lead-free glass frit, in terms of oxide, Bi ₂ O ₃ is 80 mass%, B ₂ O ₃ is 15 mass%, SiO ₂ is 2 mass%, ZrO ₂ is 0.7 mass%, Cr ₂ O ₃ Is preferably 0.6% by mass, Al ₂ O ₃ 0.3% by mass, ZnO 0.1% by mass, and Na ₂ O 1.3% by mass. The lead-free glass frit having this composition corresponds to GF1 used in Examples described later.

  The softening start temperature of the lead-free glass frit is 400 ° C. or lower, preferably 300 to 400 ° C., more preferably 340 to 400 ° C. As a result, the wettability to the copper powder and the ceramic substrate is improved, and the lead-free glass frit sufficiently penetrates into the copper powder and the ceramic substrate, so that the adhesion of the metallized wiring to the ceramic substrate can be improved. it can. The softening start temperature of the lead-free glass frit can be arbitrarily adjusted by changing the composition and average particle diameter of the lead-free glass frit.

  The ratio of the lead-free glass frit is preferably 1 to 20 parts by mass, more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the copper powder. The average particle size of the non-lead glass frit is preferably 0.5 to 5 μm.

Copper (I) oxide is cuprous oxide (Cu ₂ O) and is usually contained in the copper paste composition in a powder state. Here, the above-mentioned non-lead glass frit tends to hardly exhibit adhesion to the ceramic substrate when fired in a non-oxygen atmosphere. When a copper paste composition containing copper oxide (I) is fired in a non-oxygen atmosphere, a small amount of oxygen is introduced from the copper oxide (I) into the fire atmosphere during firing. In addition, the non-lead glass frit exhibits adhesion to the ceramic substrate.

  The ratio of copper oxide (I) is preferably 1 to 20 parts by mass and more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the copper powder. The average particle diameter when the form of copper oxide (I) is powder is preferably 1 to 5 μm.

  The copper paste composition preferably further contains a coupling agent. The coupling agent has an effect of reducing the contact between the copper powder and oxygen described above. Therefore, when a copper paste composition contains a coupling agent, it can suppress that copper powder is oxidized.

  As the coupling agent, for example, vinylmethoxysilane, vinylethoxysilane, vinyltrichlorosilane, chloropropyltrimethoxysilane, aminopropyltrimethoxysilane, aminopropyltriethoxysilane, N- (aminoethyl) aminopropyltrimethoxysilane, N -(Aminoethyl) aminopropylmethyldimethoxysilane, glycidoxypropyltrimethoxysilane, glycidoxypropylmethyldiethoxysilane, glycidoxypropyltriethoxysilane, p-styryltrimethoxysilane, (3,4 epoxy cyclohexyl) Ethyltrimethoxysilane, methacryloxypropyltrimethoxysilane, methacryloxypropylmethyldimethoxysilane, methacryloxypropylmethyldiethoxysilane, methacrylate Roxypropyltriethoxysilane, acryloxypropyltrimethoxysilane, mercaptopropyltrimethoxysilane, mercaptopropylmethyldimethoxysilane, bis (triethoxysilylpropyl) tetrasulfide, isocyanatepropyltriethoxysilane, tetramethoxysilane, tetraethoxysilane, methyl Silane coupling agents such as trimethoxysilane, methyltriethoxysilane, dimethyltriethoxysilane, phenyltriethoxysilane, hexamethyldisilazane, hexyltrimethoxysilane, decyltrimethoxysilane; tetraisopropyl titanate, isopropyltriisostearoyl titanate, Isopropyltrioctanoyl titanate, isopropyl dimethacrylisostearoyl titanate , Isopropyl isostearoyl diacryl titanate, isopropyl tris (dioctyl pyrophosphate) titanate, tetranormal butyl titanate, butyl titanate dimer, tetra (2-ethylhexyl) titanate, tetramethyl titanate, titanium acetylacetonate, titanium tetraacetylacetonate, titanium Ethyl acetoacetate, titanium octanediolate, tetraoctyl bis (ditridecyl phosphite) titanate, tetra (2,2-diallyloxymethyl-1-butyl) bis (ditridecyl) phosphite titanate, bis (dioctyl pyrophosphate) oxyacetate Titanate, bis (dioctylpyrophosphate) ethylene titanate, titanium lactate, titanium triethanolate Titanium coupling agents such as minates and polyhydroxy titanium stearates; zirconium normal propyrate, zirconium normal butyrate, zirconium monoacetylacetonate, zirconium bisacetylacetonate, zirconium tetraacetylacetonate, zirconium monoethylacetoacetate, zirconium acetate , Zirconium coupling agents such as zirconium acetylacetonate bisethylacetoacetate and zirconium monostearate; aluminum isopropylate, monosec-butoxyaluminum diisopropylate, aluminum sec-butyrate, aluminum ethylate, ethylacetoacetate aluminum diisopropylate , Aluminum tris (ethyl acetoacetate ), Alkyl acetoacetate aluminum diisopropylate, aluminum monoacetylacetonate bis (ethylacetoacetate), aluminum tris (acetylacetonate), aluminum monoisopropoxymonooroxyethylacetoacetate, cyclic aluminum oxide isopropylate, cyclic aluminum oxide Examples thereof include aluminum coupling agents such as octylate and cyclic aluminum oxide stearate, and these may be used alone or in combination. About 0.1-5 mass parts is suitable for the ratio of a coupling agent with respect to 100 mass parts of copper powder.

  The copper paste composition preferably further contains a resin binder. As a resin binder, what contains an acrylic resin and a nitrocellulose resin is preferable. As a result, moderate thixotropy is imparted to the copper paste composition, so that the copper paste composition can be printed and applied to a ceramic substrate with a fine wiring pattern, and metallized wiring can be formed with a uniform line width. can do.

  The acrylic resin has a glass transition temperature different from each other, and both are (meth) acrylic acid ester copolymers obtained by copolymerizing an H component and a L component made of (meth) acrylic acid ester at a ratio described later (hereinafter, “ It is preferably referred to as "copolymer P". (Meth) acrylic acid ester means acrylic acid ester or methacrylic acid ester. The (meth) acrylic acid ester copolymer means a copolymer of acrylic acid ester, a copolymer of methacrylic acid ester, or a copolymer of acrylic acid ester and methacrylic acid ester.

  In the copolymer P, when the glass transition temperature of the homopolymer in the H component is Tgh (° C.) and the glass transition temperature of the homopolymer in the L component is Tgl (° C.), the Tgh is 100 ° C. or higher, preferably 100 to 120 It is preferable that it is 100 degreeC, More preferably, it is 100-110 degreeC, and the value of Tgh-Tgl is 50 degreeC or more. In order to easily control the rheology of the copper paste composition, the value of Tgh-Tgl is preferably 250 ° C. or less, more preferably 150 ° C. or less, and further preferably 100 ° C. or less. . As Tgl, about 10-60 degreeC is suitable.

  Examples of the H component include adamantyl acrylate (Tgh = 153 ° C.), dimethyladamantyl acrylate (Tgh = 106 ° C.), biphenyl acrylate (Tgh = 110 ° C.), cyanobutyl acrylate (Tgh = 111 to 123 ° C.), cyanoheptyl acrylate ( Acrylates such as Tgh = 116 ° C. and cyanomethyl acrylate (Tgh = 160 ° C.); methyl methacrylate (Tgh = 105 ° C.), acrylonitrile methacrylate (Tgh = 110 ° C.), adamantyl methacrylate (Tgh = 141 ° C.), dimethyl adamantyl methacrylate (Tgh = 196 ° C.), tert-butyl methacrylate (Tgh = 118 ° C.), cyanomethylphenyl methacrylate (Tgh = 128 ° C.), cyanophenyl methacrylate Tgh = 155 ° C.), dimethylbutyl methacrylate (Tgh = 108 ° C.), isobornyl methacrylate (Tgh = 110 ° C.), methoxycarbonylphenyl methacrylate (Tgh = 106 ° C.), phenyl methacrylate (Tgh = 110 ° C.), trimethylcyclohexyl methacrylate ( And methacrylates such as Tgh = 125 ° C. and xylenyl methacrylate (Tgh = 125 to 167 ° C.). From the viewpoint of thermal decomposability, methacrylate is preferred. From the viewpoint of cost, methyl methacrylate is preferable.

  The L component can be selected from the acrylates and methacrylates exemplified for the H component as long as the Tgh-Tgl value is 50 ° C. or higher. Also in the L component, methacrylate is preferable from the viewpoint of thermal decomposability, and butyl methacrylate (Tgl = 20 ° C.) or isobutyl methacrylate (Tgl = 48 ° C.), which is a general-purpose methacrylate, is preferable from the viewpoint of cost.

  It is preferable to copolymerize the H component and the L component described above with respect to the copolymer P obtained by copolymerizing them in such a ratio that the total molar fraction of the H component and the L component is 80 mol% or more. That is, the total number of moles of monomer units constituting the copolymer P is Pm, the number of moles of H component monomer units constituting the copolymer P is Hm, and the number of moles of L component monomer units constituting the copolymer P is It is preferable to set the copolymer composition ratio so that (Hm + Lm) /Pm≧0.8 when Lm is satisfied.

  Each ratio of the H component and the L component is not particularly limited, and may be appropriately selected according to the desired rheology of the copper paste composition. The rheology of the copper paste composition tends to be dominated by elastic properties when the H component is large, and by viscous properties when the L component is large. From the viewpoint of viscoelastic balance, the molar ratio of Hm to Lm is preferably Hm: Lm = 7: 3 to 3: 7, and more preferably 6: 4 to 4: 6.

  Moreover, it is preferable that the copolymer P is further copolymerized with a polar functional group-containing (meth) acrylic acid ester. As a result, the thermal decomposability of the resin binder can be improved, an appropriate viscosity and thixotropy can be imparted to the copper paste composition, and the viscosity stability over time can be maintained.

  The polar functional group-containing (meth) acrylic acid ester is preferably at least one selected from a hydroxyl group-containing (meth) acrylic acid ester and a polyalkylene oxide chain-containing (meth) acrylic acid ester.

  Examples of hydroxyl group-containing (meth) acrylic acid esters include hydroxyethyl acrylate, hydroxyethyl methacrylate, hydroxybutyl acrylate, hydroxybutyl methacrylate, hydroxypropyl acrylate, hydroxypropyl methacrylate, dihydroxyethyl acrylate, dihydroxyethyl methacrylate, dihydroxypropyl acrylate, dihydroxy Propyl methacrylate, dihydroxybutyl acrylate, dihydroxybutyl methacrylate, (poly) ethylene glycol monoacrylate, (poly) ethylene glycol monomethacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerin monoacrylate, glycerin monometa Relate and the like.

  Examples of the polyalkylene oxide chain-containing (meth) acrylic acid ester include polymethylene oxide monoacrylate, polymethylene oxide monomethacrylate, polyethylene oxide monoacrylate, polyethylene oxide monomethacrylate, polypropylene oxide monoacrylate, and polypropylene oxide monomethacrylate. .

  The end of the exemplified hydroxyl group-containing (meth) acrylate ester and polyalkylene oxide chain-containing (meth) acrylate ester is, for example, terminated with a hydroxyl group, or terminated with an alkoxy group such as a methyl group or an ethyl group. Those are preferably used. Specific examples include methoxy (poly) ethylene glycol monomethacrylate and the like. The proportion of the polar functional group-containing (meth) acrylic acid ester is preferably 20 mol% or less with respect to Pm.

  The copolymer P described above can be produced by, for example, solution polymerization, suspension polymerization, emulsion polymerization, and the like, and solution polymerization is preferable from the viewpoint of easy handling. A more detailed description of the copolymer P is described in, for example, JP 2008-202041 A.

  On the other hand, when the resin binder contains a nitrocellulose resin together with the acrylic resin described above, the rheological properties of the copper paste composition represented by the viscosity and thixotropy suitable for printability such as screen printing are further improved. be able to.

  The nitrocellulose resin is usually obtained by esterifying the hydroxyl group of natural cellulose with nitric acid ester. However, the solubility and viscosity in the solvent described later depend on the degree of substitution (nitrification degree) or the degree of polymerization at that time. It is desirable to select a cellulose resin. The ratio of the nitrocellulose resin is preferably 1 to 20% by mass and more preferably 5 to 15% by mass with respect to the total amount of the acrylic resin and the nitrocellulose resin.

  Examples of the resin binder other than the acrylic resin and nitrocellulose resin described above include polymers such as acrylic, polyvinyl acetal, cellulose, polyvinyl alcohol, polyvinyl acetate, polyvinyl chloride, and polypropylene carbonate. You may use these 1 type or in mixture of 2 or more types. These polymers may be homopolymers of one kind of monomer or may be copolymers of different kinds of monomers.

  Examples of the monomer constituting the acrylic polymer include methyl acrylate, methyl methacrylate, ethyl acrylate, ethyl methacrylate, n-propyl acrylate, n-propyl methacrylate, isopropyl acrylate, isopropyl methacrylate, n-butyl acrylate, and n-butyl. Methacrylate, isobutyl acrylate, isobutyl methacrylate, tert-butyl acrylate, tert-butyl methacrylate, cyclohexyl acrylate, cyclohexyl methacrylate, 2-ethylhexyl acrylate, 2-ethylhexyl methacrylate, isononyl acrylate, isononyl methacrylate, isodecyl acrylate, isodecyl methacrylate, etc. Is mentioned.

  These copolymers having an acrylic ester or an alkyl methacrylate as the main chain include, for example, a monomer having a carboxylic acid group, an alkylene oxide group, a hydroxyl group, a glycidyl group, an amino group or an amide group as a copolymerization component. Can be used suitably. Further, other copolymerizable acrylonitrile, styrene, ethylene, vinyl acetate, n-vinylpyrrolidone, and the like may be copolymerized with the copolymer having the acrylic acid ester or methacrylic acid alkyl ester as the main chain.

  Examples of the monomer having a carboxylic acid group include acrylic acid, methacrylic acid, maleic acid, itaconic acid, and fumaric acid. Examples of the monomer having an alkylene oxide group include methylene oxide, ethylene oxide, and propylene oxide. Examples of the monomer having a hydroxyl group include 2-hydroxyethyl acrylate, 2-hydroxyethyl methacrylate, 2-hydroxybutyl acrylate, 2-hydroxybutyl methacrylate, diethylene glycol monoacrylate, diethylene glycol monomethacrylate, glycerin monoacrylate, glycerin monomethacrylate, Trimethylolpropane triacrylate, trimethylolpropane trimethacrylate, etc. Examples of the monomer to be used include glycidyl acrylate and glycidyl methacrylate, and examples of the monomer having an amino group or an amide group include dimethylaminoethyl acrylate, dimethylaminoethyl methacrylate, diethylaminoethyl acrylate, diethylaminoethyl methacrylate, N-tert- Examples include butylaminoethyl acrylate, N-tert-butylaminoethyl methacrylate, acrylamide, cyclohexyl acrylamide, cyclohexyl methacrylamide, N-methylol acrylamide, and diacetone acrylamide.

  Examples of the polyvinyl acetal polymer include polyvinyl butyral, polyvinyl ethylal, polyvinyl propylal, polyvinyl octylal, polyvinyl phenylal, and derivatives thereof.

  Examples of the cellulose polymer include methyl cellulose, ethyl cellulose, carboxymethyl cellulose, hydroxypropyl cellulose, hydroxypropyl methyl cellulose, and cellulose acetate.

  The weight average molecular weight of the resin binder is preferably 20,000 to 100,000. Thereby, the viscosity, thixotropy, or stringiness suitable for printability, such as screen printing, can be provided to a copper paste composition. The ratio of the resin binder is preferably 1 to 20 parts by mass and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the copper powder.

  In addition, about the composition and composition ratio of the resin binder in a copper paste composition, it can measure by using GC-Mass (gas chromatograph mass spectrometry) or NMR (nuclear magnetic resonance analysis) etc., for example. Further, the above Tgh and Tgl can be measured by using a DSC (differential thermal scanning calorimeter) or the like for a homopolymer polymerized from each raw material monomer. Further, Tgh and Tgl are measured by a measuring device such as DSC, Fox's formula; 1 / Tg = w1 / Tg1 + w2 / Tg2 (wherein w1, Tg1 and w2, Tg2 are homopolymers) The weight fraction of components 1 and 2 and the glass transition temperature are shown.).

  The copper paste composition preferably further contains a solvent. As the solvent, a high boiling point solvent is suitable. Examples of the high boiling point solvent include terpineol, dihydroterpineol, ethyl carbitol, butyl carbitol, carbitol acetate, butyl carbitol acetate, diisopropyl ketone, methyl cellosolve acetate, Cellosolve acetate, butyl cellosolve, butyl cellosolve acetate, cyclohexanone, cyclohexanol, isophorone, cypropylene glycol, propylene glycol monomethyl ether, propylene glycol monomethyl ether acetate, butyl carbitol methyl-3-hydroxyhexanoate, trimethylpentanediol Monoisobutyrate, pine oil, mineral spirit, etc. are mentioned, and these are used alone or in combination of two or more. It may be.

  The selection of the solvent is important, and the rheological properties of the copper paste composition depend on the compatibility with the above-described resin binder. In general, as the difference in SP value (solubility parameter) between the resin binder and the solvent increases, the copper paste composition tends to increase in viscosity or increase in thixotropy. Moreover, when the solubility with respect to the solvent of a resin binder is high, while handling becomes easy, it becomes easy to maintain the temporal stability of the viscosity of a copper paste composition. It is preferable that the ratio of a solvent is 1-20 mass parts with respect to 100 mass parts of copper powder, and it is more preferable that it is 10-20 mass parts.

  The copper paste composition preferably further contains a thixotropic agent. Examples of the thixotropic agent include hydrogenated castor oil, amide wax, oxidized polyethylene, polysaccharide aliphatic ester, and the like. These may be used alone or in combination.

  Of the exemplified thixotropic agents, those containing hydrogenated castor oil and amide wax are particularly preferred. As a result, moderate thixotropy is imparted to the copper paste composition, so that the copper paste composition can be printed and applied to a ceramic substrate with a fine wiring pattern, and metallized wiring can be formed with a uniform line width. can do.

  The ratio of the thixotropic agent is preferably 0.1 to 5 parts by mass, more preferably 0.1 to 2 parts by mass with respect to 100 parts by mass of the copper powder. When hydrogenated castor oil and amide wax are included as a thixotropic agent, the ratio of hydrogenated castor oil and amide wax is, by mass ratio, hydrogenated castor oil: amide wax = 9: 1 to 1: 9. Is preferable, 9: 1 to 5: 5 is more preferable, and 8: 2 to 6: 4 is more preferable.

  A plasticizer or a lubricant may be added to the copper paste composition. Examples of plasticizers or lubricants include dimethyl phthalate, dibutyl phthalate, di-2-ethylhexyl phthalate, diheptyl phthalate, di-n-octyl phthalate, diisononyl phthalate, diisodecyl phthalate, butyl benzyl phthalate, ethyl phthalyl ethyl glycolate, butyl Phthalates such as phthalylbutyl glycolate; Aliphatic esters such as di-2-ethylhexyl adipate and dibutyl diglycol adipate; Diethylene glycol, triethylene glycol, polyethylene glycol, diethylene glycol methyl ether, triethylene glycol methyl ether, diethylene glycol Ethyl ether, diethylene glycol-n-butyl ether, triethylene glycol-n-butyl ether Ethylene glycols such as ethylene glycol phenyl ether, ethylene glycol n-acetate, diethylene glycol monohexyl ether, diethylene glycol monovinyl ether; dipropylene glycol, tripropylene glycol, polypropylene glycol, dipropylene glycol methyl ether, tripropylene glycol methyl ether , Dipropylene glycol monoethyl ether, dipropylene glycol-n-butyl ether, tripropylene glycol-n-butyl ether, propylene glycol phenyl ether, ethylene glycol benzyl ether, ethylene glycol isoamyl ether, and the like; glycerin, diglycerin, poly Glycerin type such as glycerin And the like. About 0.1-10 mass parts is suitable for the ratio of a plasticizer or a lubricant with respect to 100 mass parts of copper powder.

  A dispersant may be added to the copper paste composition. Examples of the dispersant include polyoxyethylene glycol, polyoxypropylene glycol, polyoxyethylene alkyl ether, polyoxyethylene alkyl phenyl ether, glycerin fatty acid partial ester, sorbitan fatty acid partial ester, pentaerythritol fatty acid partial ester, polyoxyethylene sorbitan acid Nonionic surfactants such as fatty partial esters, polyoxyethylene alkyl ether carboxylates, fatty acid alkanolamides, polyoxyalkylene alkylamines, alkyldialkylamine oxides; alkylamine salts, dialkylamine salts, quaternary ammonium salts, etc. Cationic surfactants; ether carboxylates, dialkyl sulfosuccinates, alkane sulfonates, alkyl benzene sulfonic acids , Alkyl naphthalene sulfonate, polyoxyethylene alkyl sulfophenyl ether salt, alkyl phosphate ester salt, polyoxyethylene alkyl ether phosphate ester salt, fatty acid alkyl ester sulfate ester, alkyl sulfate ester salt, polyoxyethylene alkyl ether sulfate ester Anionic surfactants such as salts, fatty acid monoglyceride sulfates, acylated amino acid salts; amphoteric surfactants such as betaine amphoteric surfactants and amino acid amphoteric surfactants; polyvinyl alcohol, starch, starch derivatives, carboxy Examples thereof include cellulose derivatives such as methylcellulose, methylcellulose, and hydroxyethylcellulose, and polymer-type emulsifying dispersants such as sodium polyacrylate. About 0.1-1 mass part is suitable for the ratio of a dispersing agent in conversion of solid content with respect to 100 mass parts of copper powder.

  The copper paste composition according to the present invention described above is suitable for forming a metallized wiring or the like of a ceramic wiring board. Here, the metallized wiring is required to be formed on the ceramic substrate with a predetermined wiring pattern with high positional accuracy. This requirement is remarkable in a multi-piece ceramic wiring board that manufactures a large number of mounting boards on which electronic components such as LEDs are mounted from one ceramic wiring board.

  The metallized wiring is usually formed by either a co-fired method or a post-fired method. In the cofire method, a copper paste composition is printed and applied onto a ceramic green sheet, and these are simultaneously fired to form a metallized wiring on a ceramic substrate. According to the cofire method, a ceramic wiring board can be efficiently obtained by simultaneous firing, but the metallized wiring formed on the ceramic wiring board is misaligned due to shrinkage variation of the ceramic green sheet during firing. It is easy to generate.

  On the other hand, in the post-fire method, the ceramic green sheet is fired in advance to obtain a ceramic substrate that is a ceramic sintered body, and the copper paste composition is printed on the ceramic substrate and fired, and then metallized on the ceramic substrate. A wiring is formed. Therefore, according to the postfire method, by forming the copper paste on the ceramic substrate once fired and shrunk, it is possible to suppress misalignment due to shrinkage variation at the time of firing. It can be formed on the ceramic substrate with a predetermined wiring pattern with high positional accuracy. The copper paste composition according to the present invention can be suitably used as this copper paste composition for postfire.

  The post-fire method will be described more specifically. First, a ceramic green sheet is produced. In producing the ceramic green sheet, first, if necessary, a sintering aid is added to the raw material powder and mixed to obtain a mixture. Examples of the raw material powder include ceramic powder and glass frit.

  Examples of the ceramic powder include metal oxide particles, nonmetal oxide particles, and nonoxide particles. Specific examples of the ceramic powder include Li, K, Mg, B, Al, Si, Cu, Ca, Br, Ba, Zn, Cd, Ga, In, lanthanoid, actinoid, Ti, Zr, Hf, Bi, V, Examples thereof include carbides, nitrides, borides, sulfides, and the like of elements such as Nb, Ta, W, Mn, Fe, Co, and Ni.

Other examples of the ceramic powder include composite oxides of at least one selected from SiO ₂ , Al ₂ O ₃ , ZrO ₂ and TiO ₂ and an alkaline earth metal oxide. Other examples of the ceramic powder include ZnO, MgO, MgAl ₂ O ₄ , ZnAl ₂ O ₄ , MgSiO ₃ , Mg ₂ SiO ₄ , Zn ₂ SiO ₄ , Zn ₂ TiO ₄ , SrTiO ₃ , CaTiO ₃ , MgTiO _3. , BaTiO ₃ , CaMgSi ₂ O ₆ , SrAl ₂ Si ₂ O ₈ , BaAl ₂ Si ₂ O ₈ , CaAl ₂ Si ₂ O ₈ , Mg ₂ Al ₄ Si ₅ O ₁₈ , Zn ₂ Al ₄ Si ₅ O ₁₈ , AlN, Examples thereof include composite oxides containing at least one selected from Si ₃ N ₄ , SiC, Al ₂ O ₃ and SiO ₂ , that is, spinel, mullite, cordierite and the like. The average particle size of the ceramic powder is suitably about 1 to 10 μm.

Examples of the glass constituting the glass frit include SiO ₂ —B ₂ O ₃ glass, SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ glass, and SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —MO. Glass (wherein M represents Ca, Sr, Mg, Ba or Zn), SiO ₂ —Al ₂ O ₃ —M ¹ O—M ² O glass (wherein M ¹ and M ² are Each of them is the same or different and represents Ca, Sr, Mg, Ba or Zn.), SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —M ¹ O—M ² O-based glass (wherein M ¹ and M ² are the same as above.), SiO ₂ —B ₂ O ₃ —M ³ ₂ O glass (wherein M ³ represents Li, Na or K), SiO ₂ —B _{2 O 3 -Al 2 O 3 -M} 3 2 O -based glass (where, M ³ are the same as above.), Pb-based glass, Bi-based glass and the like It is.

  Other examples of the glass include glass containing at least one selected from alkali metal oxides, alkaline earth metal oxides, and rare earth oxides. These exemplified glasses include those that become amorphous glass by firing treatment. In addition, these exemplified glasses are crystallized glass that precipitates lithium silicate, quartz, cristobalite, cordierite, mullite, anorthite, serdian, spinel, garnite, willemite, dolomite, or petalite by firing. It may also contain crystallized glass that precipitates crystals of these substituted derivatives. The average particle size of the glass frit is suitably about 1 to 5 μm.

Examples of the sintering aid include B ₂ O ₃ , ZnO, MnO ₂ , alkali metal oxides, alkaline earth metal oxides, and rare earth metal oxides.

  A slurry is obtained by adding an additive such as a resin binder and a plasticizer, a solvent, and the like to the mixture obtained as described above. As the resin binder of the ceramic green sheet, for example, polymers such as acrylic, polyvinyl acetal, cellulose, polyvinyl alcohol, polyvinyl acetate, polyvinyl chloride, or polypropylene carbonate can be used. The same thing as what was illustrated in the composition is mentioned. The ratio of the resin binder is preferably 1 to 20 parts by mass and more preferably 5 to 15 parts by mass with respect to 100 parts by mass of the raw material powder.

  As a plasticizer, dibutyl phthalate etc. other than the plasticizer same as what was illustrated in the copper paste composition are mentioned. The proportion of the plasticizer is preferably 1 to 20 parts by mass and more preferably 1 to 10 parts by mass with respect to 100 parts by mass of the raw material powder.

  As the solvent, for example, toluene is suitable, but the present invention is not limited to this. About 50-150 mass parts is suitable for the ratio of a solvent with respect to 100 mass parts of raw material powders.

  Next, the obtained slurry is formed into a predetermined thickness by a forming method such as a doctor blade method, a rolling method, or a press method, and dried at an ambient temperature of 70 to 100 ° C. for about 1 hour. Get. The thickness of the ceramic green sheet is not particularly limited, and may be adjusted to a desired thickness according to the application. The ceramic green sheets may be laminated to form a ceramic green sheet laminate.

Next, the obtained ceramic green sheet is placed on, for example, an Al ₂ O ₃ setter or the like, and debindered with a predetermined temperature profile in a firing furnace having a mixed atmosphere such as nitrogen-hydrogen-steam. Thereafter, firing is performed at a maximum temperature of 1500 to 1600 ° C. to obtain a ceramic substrate.

A copper paste composition is printed and applied in a predetermined wiring pattern on the obtained ceramic substrate. For example, a screen printing method or the like is suitable for printing. Next, after drying for about 1 hour at an ambient temperature of 70 to 90 ° C., the ceramic substrate is placed on, for example, an Al ₂ O ₃ setter or the like, and a predetermined temperature profile is set in a firing furnace in a non-oxygen atmosphere. Remove the binder.

  The non-oxygen atmosphere is not particularly limited as long as the atmosphere is substantially free of oxygen, and examples thereof include a nitrogen atmosphere, a nitrogen-hydrogen mixed atmosphere, and a nitrogen-water vapor mixed atmosphere.

  Thereafter, firing is performed at a maximum temperature of 900 to 1000 ° C. to obtain a ceramic wiring substrate in which metallized wiring is formed on the ceramic substrate. When the maximum firing temperature is less than 900 ° C., the sintering of copper particles and glass components becomes insufficient, the adhesion strength of the metallized wiring decreases, and voids occur frequently in the metallized wiring, and the plating agent in the plating process is metallized. There is a possibility that the adhesiveness may be lowered due to penetration into the wiring and chemical attack of the contained glass. Moreover, when the maximum temperature of baking exceeds 1000 degreeC, copper and glass will be oversintered and there exists a possibility of causing a deformation | transformation of metallized wiring. Further, in the vicinity of the interface between the metallized wiring and the ceramic substrate, the glass component contributing to the adhesion may be excessively softened and flow out, and the adhesion may be lowered. The thickness and pattern of the metallized wiring are not particularly limited, and may be formed in a desired thickness and pattern depending on the application.

  The metallized wiring of the obtained ceramic wiring board contains copper as described above. In order to suppress the oxidation of copper, it is preferable to form a plating layer on the metallized wiring. Examples of the method for forming the plating layer include an electrolytic plating method and an electroless plating method. The layer configuration and thickness of the plating layer are not particularly limited, and a desired layer configuration and thickness can be adopted. As a specific example, two layers formed by forming a nickel (Ni) plating layer having a thickness of about 1 to 2 μm and a gold (Au) plating layer having a thickness of about 0.1 to 1 μm on the metallized wiring in this order. Examples thereof include a plating layer having a structure. In general, since the acid resistance and alkali resistance of glass components and copper particles are not sufficient, adhesion should be achieved by using a chemical solution near neutrality as much as possible and by reducing the plating process time. It is possible to further suppress the decrease in the above.

  EXAMPLES Hereinafter, although an Example is given and this invention is demonstrated further in detail, this invention is not limited to a following example.

[Examples 1 to 21 and Comparative Examples 1 to 14]
<Production of ceramic wiring board>
(Production of ceramic substrate)
First, a ceramic substrate was produced. The materials used for the production of the ceramic substrate are as follows.
Raw material powder: A glass frit made of SiO ₂ —B ₂ O ₃ —Al ₂ O ₃ —CaO—ZnO glass having an average particle diameter of 3.5 μm was used.
Resin binder: An acrylic polymer having a weight average molecular weight of 400,000 was used.
Plasticizer: Dibutyl phthalate was used.
Solvent: Toluene was used.

  11 parts by mass of a resin binder, 5 parts by mass of a plasticizer, and 80 parts by mass of a solvent were added to 100 parts by mass of the raw material powder, and mixed by a ball mill for 36 hours to obtain a slurry. This slurry was molded by a doctor blade method and dried at 80 ° C. for 1 hour using a warm air drying furnace to obtain a ceramic green sheet having a thickness of 300 μm.

This ceramic green sheet was placed on an Al ₂ O ₃ setter and debindered with a predetermined temperature profile in a firing furnace in a nitrogen-hydrogen-water vapor mixed atmosphere. Thereafter, firing was performed at a maximum temperature of 1500 to 1600 ° C. to obtain a ceramic substrate having a thickness of 250 μm.

(Preparation of copper paste composition)
Next, a copper paste composition was prepared. The materials used for the preparation of the copper paste composition are as follows.

Copper powder: Cu1 to Cu4 shown in Table 1 were used. In Table 1, T1 indicates the softening start temperature of the first plurality of copper particles, and T2 indicates the softening start temperature of the second plurality of copper particles. The softening start temperature of a plurality of copper particles is a value measured by TMA (Thermomechanical Analysis), and is measured by applying a certain load to a measurement tablet made of a plurality of copper particles. It is the heat shrink start temperature. TMA is performed, for example, by applying a certain load to the measurement tablet while raising the temperature in a reducing atmosphere or an atmosphere of nitrogen gas of 150 ml / min. The temperature rising rate in TMA is, for example, 10 ° C./min. The tablet for measurement is formed into a cylindrical shape having a diameter of 5 mm and a height of 10 mm, for example, by pressing a mixture containing a plurality of copper particles and wax at 10 ton / cm ² . D1 represents the average particle diameter of the first plurality of copper particles, and D2 represents the average particle diameter of the second plurality of copper particles.

Non-lead glass frit: GF1 to GF15 shown in Table 2 were used.

Copper (I) oxide: Copper (I) oxide having an average particle diameter of 2.5 μm was used.
Resin binder: RB1 to RB13 shown in Table 3 were used.

  In Table 3, in the column of composition, MMA is methyl methacrylate, BMA is butyl methacrylate, MPEGMA is methoxypolyethylene glycol monomethacrylate, NC is nitrocellulose resin, PEGMA is polyethylene glycol monomethacrylate, GLMA is glycerin monomethacrylate, 2HEMA is 2- Hydroxyethyl methacrylate, MAA is methacrylic acid, IBMA is isobutyl methacrylate, EMA is ethyl methacrylate, and 2EHMA is 2-ethylhexyl methacrylate.

  In the composition column, “-co-” indicates a copolymer composition, and the numerical value indicates a constituent ratio (molar ratio). Regarding the glass transition temperature, the glass transition temperature of the H component was described as Tgh, and the glass transition temperature of the L component was described as Tgl. Tgh and Tgl are values measured using DSC for homopolymers polymerized from the respective raw material monomers. The H component and the L component are described as satisfying the formula: (Hm + Lm) /Pm≧0.8. The weight average molecular weight is a value obtained by measuring by gel permeation chromatography (GPC) and converting the obtained measurement value to polystyrene.

Solvent: A mixed solvent in which terpineol and butyl carbitol acetate were mixed at a mass ratio of 5: 5 was used.
Thixo drugs: TA1 to TA5 shown in Table 4 were used.

  A copper paste composition was prepared using the above-described copper powder, non-lead glass frit, resin binder and thixotropic agent in combinations shown in Tables 5 and 6. Specifically, 5 parts by mass of non-lead glass frit, 10 parts by mass of copper oxide (I), 5 parts by mass of acrylic resin (resin binder), nitrocellulose resin (resin binder) with respect to 100 parts by mass of copper powder 0.5 parts by mass, 15 parts by mass of solvent, and 0.8 parts by mass of thixotropic agent. Then, it mixed with the 3 roll mill until aggregates, such as copper powder and a resin binder, were no longer observed visually, and obtained the copper paste composition.

(Production of ceramic wiring board)
A ceramic wiring substrate was produced using the ceramic substrate and copper paste composition obtained above. First, the copper paste composition was printed on the ceramic substrate obtained above by a screen printing method using predetermined wiring patterns A and B. The wiring patterns A and B are as follows.

Wiring pattern A: A wiring pattern having the following target design values after firing.
Shape: 1mm x 1mm square Film thickness: 12μm

Wiring pattern B: A fine wiring pattern with the target design value after firing set to the following values.
Line width: 50 μm
Film thickness: 12μm

Next, after drying at 80 ° C. for 1 hour using a hot air drying furnace, the ceramic substrate is placed on an Al ₂ O ₃ setter, and the binder is removed at a predetermined temperature profile in a firing furnace in a non-oxygen atmosphere. did. As the non-oxygen atmosphere, a mixed atmosphere of nitrogen and water vapor was employed. Thereafter, firing was performed at a maximum temperature of 950 ° C. to obtain a ceramic wiring board.

  A plating layer was formed by a conventional method on the metallized wiring of the obtained ceramic wiring board. As the plating layer, a two-layer plating layer formed by forming a Ni plating layer having a thickness of 1.5 μm and an Au plating layer having a thickness of 0.2 μm on the metallized wiring in this order was employed.

<Evaluation>
The obtained ceramic wiring board was evaluated for adhesion strength and wiring line width. Each evaluation method is shown below, and the results are also shown in Tables 5 and 6.

(Adhesion strength)
The adhesion strength was evaluated using a ceramic wiring board on which the metallized wiring of the wiring pattern A was formed. Specifically, the adhesion strength between the metallized wiring of wiring pattern A and the ceramic substrate was measured by conducting a 180 ° tensile test using lead-free solder. The test conditions are as follows.
Tensile tester: “STA-1150” manufactured by A & D Co., Ltd.
Pulling speed: 5mm / min Lead-free solder: Thickness 2-3mm
Number of measurements: 3 times The values in Table 1 are average values of n = 3.

Evaluation conditions were set as follows.
A: Adhesive strength was 3 kgf / mm ² or more.
○: Adhesion strength was 2 kgf / mm ² or more and less than 3 kgf / mm ² .
X: The adhesion strength was less than 2 kgf / mm ² .

(Wiring line width)
The wiring line width was evaluated using a ceramic wiring board on which the metallized wiring of the wiring pattern B was formed. Specifically, the line width of the metallized wiring of the wiring pattern B on which the plating layer was formed was measured with a shape measuring microscope (“VK8510” manufactured by Keyence Corporation). The measurement was performed at five arbitrarily selected locations, and the average values are shown in Table 1. The target design value including the plating layer of the metallized wiring is a line width of 50 ± 5 μm.

As is apparent from Tables 5 and 6, in Examples 1 to 21, it can be seen that metallized wiring having excellent adhesion to the ceramic substrate is formed even when fired in a non-oxygen atmosphere. Lead-free glass frit is _{ZrO 2, Cr 2 O 3,} Al 2 O 3, ZnO, In Example 1～12,16～21 further comprising a Na ₂ O, exhibited particularly excellent adhesion strength. Moreover, in Examples 1-15, the metallized wiring was able to be formed with the uniform line width, and the favorable fine printability was shown.

  On the other hand, Comparative Examples 1 to 3 in which the value of T1-T2 is less than 200 ° C. and Comparative Examples 4 to 14 in which the softening start temperature of the lead-free glass frit exceeds 400 ° C. all showed inferior adhesion strength.

Claims (11)

A copper paste composition containing at least copper powder, non-lead glass frit and copper (I) oxide,
The copper powder includes a first plurality of copper particles and a second plurality of copper particles having different softening start temperatures from each other, and the softening start temperature of the first plurality of copper particles is T1 (° C.). When the softening start temperature of the plurality of copper particles 2 is T2 (° C), the value of T1-T2 is 200 ° C or higher,
The lead-free glass frit contains at least bismuth, boron, and silicon oxides, and has a softening start temperature of 400 ° C. or lower.   When the average particle diameter of the first plurality of copper particles is D1 (μm) and the average particle diameter of the second plurality of copper particles is D2 (μm), the value of D1-D2 is 1.8 μm or more. The copper paste composition according to claim 1.   The copper paste composition according to claim 1 or 2, wherein the non-lead glass frit further contains oxides of zirconium, chromium, aluminum, zinc, and sodium.   The copper paste composition according to any one of claims 1 to 3, further comprising a resin binder containing an acrylic resin and a nitrocellulose resin. The acrylic resins have different glass transition temperatures and are copolymerized with a H component and a L component each made of (meth) acrylic acid ester in a proportion such that the total molar fraction of both components is 80 mol% or more. Made of a copolymer,
When the glass transition temperature of the homopolymer in the H component is Tgh (° C.) and the glass transition temperature of the homopolymer in the L component is Tgl (° C.), the Tgh is 100 ° C. or more, and the value of Tgh−Tgl is 50 ° C or higher,
Claims wherein the copolymer is further copolymerized with at least one polar functional group-containing (meth) acrylate selected from a hydroxyl group-containing (meth) acrylate and a polyalkylene oxide chain-containing (meth) acrylate. Item 5. The copper paste composition according to Item 4.   The copper paste composition according to any one of claims 1 to 5, further comprising a thixotropic agent.   The copper paste composition according to claim 6, wherein the thixotropic agent includes hydrogenated castor oil and amide wax.   It is an object for postfires, The copper paste composition in any one of Claims 1-7.   The copper paste composition according to any one of claims 1 to 8, which is fired at a maximum temperature of 900 to 1000 ° C in a non-oxygen atmosphere.   A ceramic structure obtained by applying the copper paste composition according to claim 1 to a ceramic sintered body and firing it.   The ceramic structure according to claim 10, which is a multi-piece ceramic wiring board.