Conductive ink, method for producing copper-nickel sintered film, and copper-nickel sintered film

Abstract

Provided are a conductive ink capable of forming metal wiring having low volume resistivity, a method for producing a copper-nickel sintered film, and a copper-nickel sintered film.　This conductive ink comprises copper particles, a copper complex, and a nickel complex, the copper complex being a complex represented by Cu(HCOO)2(L)m and the nickel complex being a complex represented by Ni(HCOO)2(L)n, where L is at least one selected from the group consisting of 2-amino-2-methyl-1-propanol, 1-amino-2-propanol, 2-amino-1-butanol, 2-(methylamino) ethanol, and 2-aminoethanol, m is a natural number of 2-6, and n is a natural number of 2-6, the ratio of copper contained in the copper complex to the total of the copper particles and the copper contained in the copper complex being 0.5-15.0 mass%, and the ratio of nickel contained in the nickel complex to the total of the copper particles, the copper contained in the copper complex, and the nickel contained in the nickel complex being 0.5-7.0 mass%.

Description

Conductive ink, method for manufacturing copper-nickel sintered film, and copper-nickel sintered film

[0001] This invention relates to conductive ink, a method for producing a copper-nickel sintered film, and a copper-nickel sintered film.

[0002] In recent years, printed electronics has been developed as a wiring technology for semiconductor devices, electronic circuits, and other components. Printed electronics is attracting attention because it can reduce manufacturing costs compared to existing semiconductor manufacturing technologies such as photolithography.

[0003] Inks using complexes have been developed for use in printed electronics (for example, Patent Document 1). Patent Document 1 discloses a conductive ink for copper-nickel alloy electrodes that is inexpensive, has excellent atmospheric stability, and enables smooth metal wiring on the surface, as well as a substrate with copper-nickel alloy electrodes and a method for manufacturing the same.

[0004] WO2022 / 130892A1

[0005] With the miniaturization of semiconductor elements and electronic circuits, the width of these metal wirings tends to decrease. However, it is preferable for the metal wiring to have sufficient thickness to suppress heat generation caused by the decrease in width and to allow a certain amount of current to flow even when miniaturized.

[0006] However, when attempting to manufacture metal wiring using conventional metal complex inks, particularly conductive inks containing copper particles, copper complexes, and nickel complexes, it was not possible to form fine-width metal wiring. Furthermore, while it was sometimes possible to form fine-width metal wiring using conductive inks containing copper complexes and nickel complexes but without copper particles, it was not possible to give the metal wiring sufficient thickness. Moreover, in metal wiring manufactured using conductive inks containing copper particles and nickel complexes but without copper complexes, although the oxidation of copper can be suppressed by the nickel metal coating the surface of the copper particles, the nickel metal inhibits the formation of conductive paths by copper. Therefore, unless the activity of copper is increased beforehand by removing the oxide film on the copper particles, it was difficult to form metal wiring with low resistivity and satisfying electrical properties.

[0007] Therefore, the present invention aims to provide a conductive ink, a method for manufacturing a copper-nickel sintered film, and a copper-nickel sintered film, which can form metal wiring with low volume resistivity.

[0008] To solve the above problems, the conductive ink of the present invention comprises copper particles, a copper complex, and a nickel complex, wherein the copper complex is Cu(HClO) ２ (L) ｍ The complex is represented by Ni(HClOO) ２ (L) ｎ The complex is represented by , where L is at least one selected from 2-amino-2-methyl-1-propanol, 1-amino-2-propanol, 2-amino-1-butanol, 2-(methylamino)ethanol, and 2-aminoethanol, m is a natural number from 2 to 6, n is a natural number from 2 to 6, the ratio of copper contained in the copper complex to the total amount of copper contained in the copper particles and the copper complex is 0.5% by mass to 15.0% by mass, and the ratio of nickel contained in the nickel complex to the total amount of copper contained in the copper particles and the copper complex and the nickel contained in the nickel complex is 0.5% by mass to 7.0% by mass.

[0009] The ratio of nickel contained in the nickel complex to the total amount of copper contained in the copper particles and the copper complex and nickel contained in the nickel complex may be 0.5% by mass to 4.7% by mass.

[0010] The number-average particle size of the copper particles may be 0.03 μm to 0.6 μm.

[0011] The copper particles may include at least two types of copper particles with different number-average particle diameters, and when the total mass of the copper particles with a large number-average particle diameter is W1 and the total mass of the copper particles with a small number-average particle diameter is W2, the mass ratio may be W1:W2 = 60 to less than 100: greater than 0 to 40.

[0012] In the conductive ink of the present invention, the shear viscosity at a shear rate of 0.1 / s may be 1.0 Pa·s to 1000.0 Pa·s, and the shear viscosity at a shear rate of 10 / s may be 1.0 Pa·s to 100.0 Pa·s.

[0013] The conductive ink of the present invention may contain an organic solvent.

[0014] Furthermore, in order to solve the above problems, the present invention provides a method for manufacturing a copper-nickel sintered film, which includes a sintering step of heating the conductive ink of the present invention to sinter the conductive ink, wherein a nickel sintered film is coated on the surface of the copper sintered film, and the ratio of nickel to the total of copper and nickel is 0.5% to 7.0% by mass.

[0015] Prior to the sintering step, a coating step may be included in which the conductive ink of the present invention is applied to a substrate.

[0016] The method for manufacturing a copper-nickel sintered film of the present invention may include a drying step of drying the conductive ink after the coating step at 80°C to 120°C, and the sintering step may be a step of sintering the conductive ink by heating at 160°C to 250°C.

[0017] The method for producing a copper-nickel sintered film of the present invention may include a light irradiation step of irradiating the copper-nickel sintered film after the sintering step with light.

[0018] Furthermore, in order to solve the above problems, the copper-nickel sintered film of the present invention is a copper-nickel sintered film in which a nickel-sintered film is coated on the surface of a copper-sintered film, and the ratio of nickel to the total of copper and nickel is 0.5% by mass to 7.0% by mass.

[0019] The initial volume resistivity R of the copper-nickel sintered film ０ It may be 200 μΩ·cm or less.

[0020] In the copper-nickel sintered film of the present invention, R may be 200 μΩ·cm or less, where R is the volume resistivity after an accelerated oxidation test in which the film is left standing at 180°C for 8 hours in air.

[0021] The present invention provides a conductive ink, a method for manufacturing a copper-nickel sintered film, and a copper-nickel sintered film, all of which can form metal wiring with low volume resistivity.

[0022] This figure shows optical microscope images of the surface of metal wiring with widths of 30 μm and 100 μm, formed by screen printing using the conductive ink of Example 5, and the results of measuring the thickness of the cross-section. This figure shows optical microscope images of the surface of metal wiring with widths of 200 μm and 2000 μm, formed by screen printing using the conductive ink of Example 5, and the results of measuring the thickness of the cross-section. This figure shows optical microscope images of the surface of metal wiring with widths of 30 μm and 100 μm, formed by screen printing using the conductive ink of Example 11, and the results of measuring the thickness of the cross-section. This figure shows optical microscope images of the surface of metal wiring with widths of 200 μm and 2000 μm, formed by screen printing using the conductive ink of Example 11, and the results of measuring the thickness of the cross-section. This figure shows optical microscope images of the surface of metal wiring with widths of 30 μm and 100 μm, formed by screen printing using the conductive ink of Example 20, and the results of measuring the thickness of the cross-section. This figure shows optical microscope images of the surface of metal wiring with widths of 200 μm and 2000 μm, formed by screen printing using the conductive ink of Example 20, and the results of measuring the thickness of the cross-section. This figure shows optical microscope images of the surface of metal wiring with widths of 30 μm and 100 μm, formed by screen printing using the conductive ink of Example 25, and the results of measuring the thickness of the cross-section. This figure shows optical microscope images of the surface of metal wiring with widths of 200 μm and 2000 μm, formed by screen printing using the conductive ink of Example 25, and the results of measuring the thickness of the cross-section. This figure shows optical microscope images of the surface of metal wiring with widths of 30 μm and 100 μm, formed by screen printing using the conductive ink of Comparative Example 5, and the results of measuring the thickness of the cross-section. This figure shows optical microscope images of the surface of metal wiring with widths of 200 μm and 2000 μm, formed by screen printing using the conductive ink of Comparative Example 5, and the results of measuring the thickness of the cross-section. This figure shows optical microscope images of the surface of metal wiring with widths of 30 μm and 100 μm, formed by screen printing using the conductive ink of Comparative Example 7. This figure also shows optical microscope images of the surface of metal wiring with widths of 200 μm and 2000 μm, formed by screen printing using the conductive ink of Comparative Example 7, and the results of measuring the thickness of the cross-section.

[0023] The conductive ink, the method for manufacturing the copper-nickel sintered film, and one embodiment of the copper-nickel sintered film of the present invention will be described below.

[0024] [Conductive Ink] The conductive ink of this embodiment includes copper particles, a copper complex, and a nickel complex, as described below.

[0025] <Copper Particles> By including copper particles together with copper and nickel complexes in the conductive ink, it is possible to form a thick metal wiring with a thickness of several micrometers or more as a copper-nickel sintered film obtained by sintering the conductive ink, in which nickel is coated onto copper.

[0026] For example, by including copper particles in conductive ink, thick metal wiring with a thickness of several micrometers or more can be formed on a substrate or other coating surface in a single application using screen printing or similar methods. This is possible because copper reduced from a copper complex precipitates on the surface of the copper particles, forming good conductive paths made of copper. Furthermore, nickel reduced from a nickel complex precipitates on these conductive paths, coating the copper and preventing oxygen from coming into contact with it, thereby preventing copper oxidation.

[0027] Specifically, the metal wiring formed with the conductive ink of this embodiment can exhibit good volume resistivity due to the conductive path of copper, and the nickel coating over the copper can suppress the increase in the volume resistivity of the metal wiring over time.

[0028] On the other hand, in the case of conductive ink that does not contain copper particles, it is not possible to form a metal wiring of sufficient thickness with a single application, and multiple applications are required to obtain sufficient thickness. However, when attempting to form fine metal wiring by screen printing, the method of repeatedly applying the ink multiple times can cause misalignment of the metal wiring after printing, making it difficult to form metal wiring with a consistent shape. Furthermore, metal wiring formed by repeatedly applying conductive ink may contain a mixture of copper layers, nickel layers, and alloys containing both copper and nickel, which may prevent it from exhibiting sufficient electrical properties.

[0029] When the number average particle diameter of the copper particles is 0.03 μm to 0.6 μm, a sufficient thickness of the metal wiring can be ensured, and the surface has few irregularities, and a crack-free metal wiring can be obtained. More preferably, the number average particle diameter of the copper particles is 0.3 μm to 0.5 μm.

[0030] As the copper particles, at least two kinds of copper particles having different number average particle diameters may be included. The copper particles having a large number average particle diameter can ensure a sufficient thickness of the metal wiring, and the copper particles having a small number average particle diameter neck (fuse) and bridge the copper particles having a large number average particle diameter, so that a good conductive path can be formed, and a thick metal wiring having a low volume resistivity can be formed.

[0031] For example, when the total mass of the copper particles having a large number average particle diameter is W1 and the total mass of the copper particles having a small number average particle diameter is W2, the mass ratio is W1:W2 = 60 to less than 100: more than 0 to 40, so that a metal wiring having a sufficiently low volume resistivity and a sufficient thickness can be formed.

[0032] <Copper complex> The copper complex is a complex represented by the general formula Cu(HCOO) ２ (L) ｍ In the general formula, L is at least one selected from 2-amino-2-methyl-1-propanol, 1-amino-2-propanol, 2-amino-1-butanol, 2-(methylamino)ethanol, and 2-aminoethanol, and m is a natural number from 2 to 6.

[0033] This copper complex is (CH ３ ) ２ C(NH ２ )CH ２ OH (2-amino-2-methyl-1-propanol, hereinafter sometimes referred to as "AMP"), CH ３ C(OH)CH ２ NH ２ (1-amino-2-propanol, hereinafter sometimes referred to as "APol"), CH ３ C(NH ２ )CH ２ OH (2-amino-1-butanol, hereinafter sometimes referred to as "ABol"), CH ３NHCH ２ CH ２ OH (2-(methylamino)ethanol, sometimes referred to as "MAEol"), NH ２ CH ２ CH ２ At least one of the following is selected from OH (2-aminoethanol, sometimes referred to as "AEol"), and copper formate (Cu(HClO)) is used as a ligand. ２ This can be described as a state in which 2 to 6 molecules are coordinated to ).

[0034] Below, (HCOO) ２ Cu((CH ３ ) ２ C(NH ２ )CH ２ OH) ２～６ The copper complex shown is called "Cu-AMP" (HCOO). ２ Cu(CH ３ C(OH)CH ２ NH ２ ) ２～６ The copper complex shown is called "Cu-APol" (HCOO). ２ Cu(CH ３ C(NH ２ )CH ２ OH) ２～６ The copper complex shown is called "Cu-ABol" (HCOO). ２ Cu(CH ３ NHCH ２ CH ２ OH) ２～６ The copper complex shown is called "Cu-MAEol" (HCOO). ２ Cu(NH ２ CH ２ CH ２ OH) ２～６ The copper complex shown is sometimes referred to as "Cu-AEol".

[0035] By including the above-mentioned copper complex along with copper particles and nickel complex in the conductive ink, it is possible to form a thick metal wiring with a thickness of several micrometers or more as a copper-nickel sintered film obtained by sintering the conductive ink, in which nickel is coated onto copper.

[0036] In other words, because the conductive ink contains a copper complex, copper reduced from the copper complex can be deposited on the surface of the copper particles, thus forming a good conductive path of copper. Since the unoxidized copper immediately after reduction from the copper complex is deposited on the surface of the copper particles, the electrical properties of the conductive path are good. Furthermore, nickel reduced from the nickel complex is deposited on the conductive path, coating the copper immediately after reduction, which prevents oxygen from coming into contact with the copper and thus prevents the oxidation of the copper.

[0037] Specifically, the metal wiring formed by the conductive ink of this embodiment can exhibit good volume resistivity due to the conductive paths formed by the deposition of reduced copper on copper particles, and furthermore, by coating the copper conductive paths with nickel, the increase in the volume resistivity of the metal wiring over time can be suppressed.

[0038] On the other hand, in the case of conductive inks that do not contain copper complexes, nickel reduced from the nickel complex precipitates on the surface of the copper particles. In this case, in addition to the formation of conductive paths where copper particles are in direct contact with each other, conductive paths are also formed through nickel between the copper particles without direct contact. Therefore, the nickel metal inhibits the formation of conductive paths between copper particles. Conductive paths, especially those mediated by nickel, are affected by the volume resistivity of nickel. Furthermore, even in conductive paths between copper particles, if an oxide film is present on the surface of the copper particles, the volume resistivity may increase due to its influence. Due to these combined factors, conductive inks that do not contain copper complexes and consist of copper particles and nickel complexes may make it difficult to form metal wiring with low volume resistivity unless the copper activity is increased beforehand by removing the oxide film from the copper particles, or even if the copper activity is increased.

[0039] <Percentage of copper in the copper complex> In this embodiment, the conductive ink has a copper content in the copper complex that is 0.5% to 15.0% by mass relative to the total amount of copper in the copper particles and the copper complex. That is, if we define "Cu(complex)" as the mass of metallic copper reduced and deposited from the copper complex in the conductive ink, and "copper particles" as the mass of copper particles in the conductive ink, then the relationship 0.5 ≤ Cu(complex) × 100 / [Cu(complex) + copper particles] ≤ 15 can be expressed by equation.

[0040] The above-mentioned copper ratio of 0.5% to 15.0% by mass ensures that the amount of copper deposited on the surface of the copper particles by the copper complex is sufficient and not excessive, thus facilitating the formation of good conductive paths. If the above-mentioned copper ratio is low, the amount of copper complex is low, and as is observed in conductive inks that do not contain copper complexes, it tends to be difficult to form metal wiring with low volume resistivity. On the other hand, if the above-mentioned copper ratio is high, the amount of copper particles is low, and as is observed in conductive inks that do not contain copper particles, it may not be possible to form metal wiring of sufficient thickness with a single application.

[0041] <Nickel complexes> Nickel complexes have the general formula Ni(HCOO) ２ (L) ｎ The complex is represented by the formula. In the general formula, L is at least one selected from 2-amino-2-methyl-1-propanol, 1-amino-2-propanol, 2-amino-1-butanol, 2-(methylamino)ethanol, and 2-aminoethanol, and n is a natural number from 2 to 6.

[0042] This nickel complex is (CH ３ ) ２ C(NH ２ )CH ２ OH (2-amino-2-methyl-1-propanol, hereafter sometimes referred to as "AMP"), CH ３ C(OH)CH ２ NH ２ (1-amino-2-propanol, sometimes referred to as "APol") CH ３ C(NH ２ )CH ２OH (2-amino-1-butanol, hereinafter sometimes referred to as "ABol"), CH ３ NHCH ２ CH ２ OH (2-(methylamino)ethanol, hereinafter sometimes referred to as "MAEol"), NH ２ CH ２ CH ２ OH (2-aminoethanol, hereinafter sometimes referred to as "AEol"), at least one selected from them can be said to be in a state where 2 to 6 molecules are coordinated to nickel formate (Ni(HCOO) ２ ).

[0043] Hereinafter, the nickel complex represented by (HCOO) ２ Ni((CH ３ ) ２ C(NH ２ CH ２ OH)) ２～６ is referred to as "Ni-AMP", (HCOO) ２ Ni(CH ３ C(OH)CH ２ NH ２ ) ２～６ is referred to as "Ni-APol", (HCOO) ２ Ni(CH ３ C(NH ２ CH ２ OH)) ２～６ is referred to as "Ni-ABol", (HCOO) ２ Ni(CH ３ NHCH ２ CH ２ OH)) ２～６ is referred to as "Ni-MAEol", (HCOO) ２ Ni(NH ２ CH ２ CH ２ OH)) ２～６ may be referred to as "Ni-AEol".

[0044] By including the above nickel complex together with copper particles and a copper complex in the conductive ink, as a copper-nickel sintered film obtained by sintering the conductive ink, a thick metal wiring with a thickness of several μm or more in which nickel covers copper can be formed.

[0045] As described above, the copper particles and copper complex in the conductive ink cause reduced copper from the copper complex to precipitate on the surface of the copper particles, forming good conductive paths for copper. Furthermore, if the conductive ink contains a nickel complex, reduced nickel from the nickel complex precipitates on the conductive paths, coating the copper immediately after reduction. This prevents oxygen from coming into contact with the copper, thus preventing copper oxidation.

[0046] On the other hand, in the case of conductive inks that do not contain nickel complexes, although reduced copper from the copper complex is deposited on the surface of copper particles, nickel is not present to suppress the oxidation of the copper particles or the deposited copper. Therefore, although excellent volume resistivity can be achieved immediately after the formation of the metal wiring due to good conductive paths, oxidation of the conductive paths progresses over time, and it may not be possible to maintain excellent volume resistivity.

[0047] <Ratio of nickel in the nickel complex> In this embodiment, the conductive ink has a nickel content of 0.5% to 7.0% by mass relative to the total amount of copper in the copper particles and copper complex and nickel in the nickel complex. That is, if we let the mass of metallic copper deposited by reduction from the copper complex in the conductive ink be "Cu(complex)", the mass of copper particles in the conductive ink be "copper particles", and the mass of metallic nickel deposited by reduction from the nickel complex in the conductive ink be "Ni(complex)", then the relationship 0.5 ≤ Ni(complex) × 100 / [Cu(complex) + copper particles + Ni(complex)] ≤ 7.0 can be expressed by equation.

[0048] The nickel content being between 0.5% and 7.0% by mass allows the nickel reduced from the nickel complex to sufficiently coat the surface of the conductive path formed by the copper particles and the copper reduced from the copper complex. This suppresses oxidation of the conductive path and thus inhibits the increase in volume resistivity over time. However, if the nickel content is low, the amount of nickel complex decreases, and as can be seen in conductive inks that do not contain nickel complexes, oxidation of the conductive path progresses over time, making it difficult to maintain the excellent volume resistivity of the metal wiring.

[0049] The nickel content described above is more preferably 0.5% to 4.7% by mass. Furthermore, it may be 0.5% to 2.8% by mass.

[0050] If a conductive ink containing copper particles, copper complexes, and nickel complexes satisfies these conditions, heating and sintering will release the formic acid and ligands, forming a copper-nickel sintered film together with the copper particles. The resulting copper-nickel sintered film has low volume resistivity, excellent conductivity, and smoothness, and it is possible to form fine metal wiring by printing with the copper complex ink.

[0051] The conductive ink of this embodiment may have a shear viscosity of 1.0 Pa·s to 1000.0 Pa·s at a shear rate of 0.1 / s, and a shear viscosity of 1.0 Pa·s to 100.0 Pa·s at a shear rate of 10 / s. These values ​​are guidelines for indicating the printing characteristics of the conductive ink when screen printing is assumed. When screen printing is performed using conductive ink, i.e., when the shear rate is high, it is important that the conductive ink exhibits excellent fluidity like a liquid to improve screen penetration. After the conductive ink has penetrated the screen and the shear rate is slow, it is important that the conductive ink exhibits solid-like behavior to maintain the printed shape. These characteristics can be satisfied within the above numerical ranges.

[0052] The conductive ink of this embodiment may contain an organic solvent. The organic solvent is not particularly limited, and examples thereof include hydrocarbon solvents, alcohol solvents, ketone solvents, ester solvents, ether solvents, glycol solvents, glyme solvents, halogen solvents, aromatic solvents, and heterocyclic-containing solvents. More specifically, as the alcohol, methanol, ethanol, propanol, butanol, pentanol, etc. can be used, and as the glycol and ether, ethylene glycol, propylene glycol, 1,3-propanediol, 1,2-butanediol, 1,3-butanediol, 1,4-butanediol, diethylene glycol, dipropylene glycol, triethylene glycol, diethylene glycol monoethyl ether, dipropylene glycol monomethyl ether, diethylene glycol monoethyl ether, triethylene glycol dimethyl ether, diethylene glycol monobutyl ether, etc. can be used. In addition, glycerin, diethylene glycol monobutyl acetate, dimethylacetamide, diacetone alcohol, etc. can also be used.

[0053] In addition, as additives, for example, an adhesion promoter, a surface conditioner, an antifoaming agent, a rheology control agent, reducing agents such as ascorbic acid, formic acid, and oxalic acid can be included in the conductive ink.

[0054] [Manufacturing method of conductive ink] The manufacturing method of the above conductive ink is not particularly limited, and for example, the conductive ink can be manufactured by the method described below.

[0055] Note that the following example is an example of manufacturing a copper complex represented by the general formula (HCOO) ２ Cu((CH ３ )) ２ C(NH ２ )CH ２ OH) ２ This complex is (CH ３ ) ２ C(NH ２ )CH ２OH (2-amino-2-methyl-1-propanol, hereafter sometimes referred to as "AMP") acts as a ligand for copper formate (Cu(HClOO) ２ This can be described as a state in which two molecules are coordinated to (HCOO). ２ Cu((CH ３ ) ２ C(NH ２ )CH ２ OH) ２ The copper complex shown is sometimes referred to as "Cu-AMP".

[0056] Furthermore, the nickel complex has the general formula (HCOO). ２ Ni(CH ３ C(OH)CH ２ NH ２ ) ２ This is an example of producing the nickel complex shown. This complex is CH ３ C(OH)CH ２ NH ２ (1-amino-2-propanol, hereafter sometimes referred to as "APol") is used as a ligand for nickel formate (Ni(HClO) ２ This can be described as a state in which two molecules are coordinated to (HCOO). ２ Ni(CH ３ C(OH)CH ２ NH ２ ) ２ The nickel complex shown is sometimes referred to as "Ni-APol".

[0057] <Manufacturing of Copper Complex Ink> (Raw Materials for Copper Complex Ink) The raw material for copper complex ink is Cu(HClO) ２ 4H ２ O powder and (CH ３ ) ２ C(NH ２ )CH ２ Solid OH can be used. (CH ３ ) ２ C(NH ２ )CH ２ OH is Cu (HCOO) ２ Since it coordinates with two molecules, the molar ratio when mixing them is Cu(HClO) ２ 4H ２ O: (CH ３ )２ C(NH ２ )CH ２ It is preferable that the OH ratio be 1:2, and this molar ratio is acceptable within the range of 1:1.8 to 2.2. Cu(HClOO) ２ 4H ２ O powder and (CH ３ ) ２ C(NH ２ )CH ２ OH can be stirred using the following stirring process.

[0058] (Crushing process) Cu (HCOO) ２ 4H ２ O absorbs moisture from the atmosphere, increasing in weight, and may also aggregate and form clumps. Therefore, in order to crush these clumps and facilitate the mixing of the raw materials, Cu(HClO) is used before the stirring process described later. ２ 4H ２ The process may include a grinding step in which the powder of O is ground.

[0059] (Agitation process) The mixture is heated into a container and made into a liquid (CH ３ ) ２ C(NH ２ )CH ２ OH is added and stirred with a hot stirrer at 40°C and 500 rpm, and then Cu(HClO) after the grinding process is added. ２ 4H ２ Add oxygen and continue stirring. After stirring for 24 hours, change the stirring conditions to 25°C and 100 rpm and stir for a total of 96 hours to produce Cu-AMP as a copper complex.

[0060] Furthermore, when producing copper complexes, the mixing equipment and mixing conditions in the stirring process can be set as appropriate.

[0061] <Manufacturing of Nickel Complex Ink> (Raw Materials for Nickel Complex Ink) The raw material for nickel complex ink is Ni(HCOO) ２ ・2H ２ Powdered O and liquid CH ３ C(OH)CH ２ NH ２ CH can be used. ３ C(OH)CH ２ NH ２Ni(HCOO) ２ Since it coordinates with two molecules, the molar ratio when mixing them is Ni(HClO) ２ ・2H ２ O:CH ３ C(OH)CH ２ NH ２ A ratio of 1:4 is preferred, and this molar ratio is acceptable within the range of 1:3.8 to 4.2. Ni(HCOO) ２ ・2H ２ O powder and CH ３ C(OH)CH ２ NH ２ This can be stirred using the following stirring process.

[0062] (Crushing process) Ni (HCOO) ２ ・2H ２ O absorbs moisture from the atmosphere, increasing in weight and sometimes agglomerating to form clumps. Therefore, in order to crush these clumps and facilitate the mixing of the raw materials, Ni(HClO) is used before the stirring process described later. ２ ・2H ２ The process may include a grinding step in which the powder of O is ground.

[0063] (Agitation process) Put CH into a container ３ C(OH)CH ２ NH ２ Add the following and stir with a hot stirrer at 25°C and 500 rpm, then add the Ni(HClO) after the grinding process. ２ ・2H ２ By adding oxygen and continuing stirring for 24 hours, Ni-APol can be produced as a nickel complex.

[0064] Furthermore, when manufacturing nickel complexes, the mixing equipment and mixing conditions in the stirring process can be set as appropriate.

[0065] <Manufacturing of conductive ink> Conductive ink can be manufactured by placing the manufactured copper complex ink, nickel complex ink, copper particles, and ethylene glycol into a container and mixing them using a rotary mixer or the like. The proportions of copper and nickel are as described above, and the amounts of copper particles and organic solvents can be set as appropriate.

[0066] Furthermore, conductive ink can be manufactured using the same procedure when ligands other than those mentioned above are coordinated to copper or nickel to form complexes.

[0067] [Method for Manufacturing Copper-Nickel Sintered Film] Next, one embodiment of the method for manufacturing the copper-nickel sintered film of this embodiment will be described. The sintered film obtained by this manufacturing method is a copper-nickel sintered film in which a nickel sintered film is coated on the surface of a copper sintered film, and the ratio of nickel to the total of copper and nickel is 0.5% to 7.0% by mass. By having a nickel ratio of 0.5% to 7.0% by mass, the nickel reduced from the nickel complex can sufficiently coat the surface of the conductive path made of copper particles and copper reduced from the copper complex, thereby suppressing the oxidation of the conductive path and thus suppressing the increase in volume resistivity over time. However, if the above-mentioned nickel ratio is low, the amount of nickel complex is low, and as can be seen in conductive inks that do not contain nickel complexes as described above, oxidation of the conductive path progresses over time, and the excellent volume resistivity of the metal wiring tends not to be maintained.

[0068] The nickel content described above is more preferably 0.5% to 4.7% by mass. Furthermore, it may be 0.5% to 2.8% by mass.

[0069] The resulting copper-nickel sintered film can be used in applications requiring conductivity in heat-treated films such as metal wiring, conductive adhesives, and die attach materials, and its shape and thickness can be arbitrarily determined. In particular, metal wiring with a line width of approximately 30 μm to 2 mm can be formed by screen printing, and line widths of 2 mm or more are also possible, allowing for the formation of metal wiring of any width.

[0070] <Sintering Process> The method for manufacturing a copper-nickel sintered film includes a sintering process. This process involves heating the conductive ink of the above embodiment to sinter the conductive ink.

[0071] The heat treatment conditions should be such that ligands such as formic acid and APol, and water (if water is inevitably present in the ink), are evaporated from the copper and nickel complexes, and the copper and nickel particles are sintered. For example, a treatment condition in which the conductive ink is sintered by heating at 160°C to 250°C can be used, and the temperature within this range may be maintained for 5 to 30 minutes to sinter. Alternatively, the conductive ink may be sintered while raising the temperature from room temperature to 160°C to 250°C. If necessary, the temperature may be raised to a set temperature and then maintained at that temperature for 0 to 60 minutes. The heating conditions can also be arbitrarily selected, for example, by setting it to 0.5°C to 20°C / minute. After heating, the sintered film may be cooled to room temperature by air cooling or other means.

[0072] To prevent the film before and after sintering from being affected by oxygen in the air during the heating, warming, and cooling processes, heating, warming, and cooling may be carried out in an inert atmosphere such as argon gas or nitrogen gas, or in a mixed gas atmosphere of nitrogen gas mixed with 3% to 5% hydrogen gas.

[0073] <Light Irradiation Step> The method for manufacturing a copper-nickel sintered film of this embodiment may include a light irradiation step in which light is irradiated onto the copper-nickel sintered film after the sintering step to further promote the sintering of the copper-nickel sintered film. By performing light irradiation, which applies instantaneous heating with powerful light energy to the copper-nickel sintered film, necking (fusion) between coppers, between nickels, and between copper and nickel can be further promoted to form a film in which these metals are more integrated, and an even lower-resistance copper-nickel sintered film can be obtained.

[0074] For light irradiation, xenon flash lamps, LED lamps, lasers, etc., are used. Since light irradiation applies a powerful amount of light energy instantaneously, the substrate may be cooled during irradiation to prevent it from overheating and melting, such as a resin film on which a copper-nickel sintered film is formed. In addition, to prevent condensation on the substrate and the copper-nickel sintered film, light irradiation may be performed in a vacuum atmosphere, an inert gas (argon, nitrogen), or a dry air atmosphere.

[0075] <Coating Process> The method for manufacturing the copper-nickel sintered film of this embodiment may include a coating process in which the conductive ink of this embodiment is applied to a substrate before the sintering process. For example, the conductive ink can be printed on a coating target such as an electronic substrate including an alumina substrate, polyimide film, PET film, PEN film, glass, etc., by screen printing, inkjet printing, gravure printing, gravure offset printing, dispenser, spin coating, etc.

[0076] <Drying Process> The method for manufacturing a copper-nickel sintered film according to this embodiment may include a step of drying the conductive ink after the coating process. Performing a drying process before the sintering process can stabilize the shape of the coated film obtained by applying the conductive ink. The drying conditions are not particularly limited, but for example, drying at 80°C to 120°C, which is the temperature at which the crystal water of copper formate evaporates, can be used. The drying time is not particularly limited, but depending on the amount of conductive ink applied, for example, it can be about 1 to 30 minutes, and drying for 5 minutes or more is more preferable.

[0077] (Other steps) The method for manufacturing the copper-nickel sintered film of this embodiment may include other steps in addition to the steps described above. For example, a step of processing the film into the shape of metal wiring may be performed.

[0078] [Copper-Nickel Sintered Film] In this embodiment, the copper-nickel sintered film has a nickel sintered film coating the surface of the copper sintered film, and the proportion of nickel to the total of copper and nickel is 0.5% to 7.0% by mass. By having a nickel proportion of 0.5% to 7.0% by mass, the nickel reduced from the nickel complex can sufficiently coat the surface of the conductive path made of copper particles and copper reduced from the copper complex, thereby suppressing the oxidation of the conductive path and preventing an increase in volume resistivity over time. However, if the above-mentioned proportion of nickel is low, the amount of nickel complex is low, and as can be seen in conductive inks that do not contain nickel complexes as described above, oxidation of the conductive path progresses over time, and the excellent volume resistivity of the metal wiring tends not to be maintained.

[0079] The copper-nickel sintered film of this embodiment can be manufactured, for example, by the method for manufacturing the copper-nickel sintered film of this embodiment described above.

[0080] The copper-nickel sintered film of this embodiment has an initial volume resistivity R ０ It has the characteristics of low volume resistivity, suppressing a large increase in the volume resistivity of the sintered film over time, and having high smoothness. These characteristics are due to the fact that the nickel sintered film smoothly coats the surface of the copper sintered film, thereby suppressing the oxidation of copper. In other words, the nickel sintered film suppresses the oxidation of copper during sintering, thereby reducing the initial volume resistivity R ０ This allows the volume resistivity to be kept low, and the nickel sintered film suppresses the oxidation of the copper sintered film over time, thereby preventing a significant increase in volume resistivity over time. Note that the initial volume resistivity R of the copper-nickel sintered film is... ０ This is the volume resistivity of the copper-nickel sintered film within one day of manufacturing.

[0081] For example, the initial volume resistivity R of the copper-nickel sintered film in this embodiment ０ R may be 200 μΩ·cm or less. Furthermore, when R is the volume resistivity of the copper-nickel sintered film after an accelerated oxidation test in which it is left standing at 180°C for 8 hours in air, R may be 200 μΩ·cm or less. ０ If R is within this range, a sufficient and stable current can be supplied to the copper-nickel sintered film of metal wiring, etc., from the initial stage to long-term normal use. However, if R as a resistance value is large, the metal wiring itself becomes a resistor, which poses a risk of overheating. To prevent this, R can be reduced by increasing the thickness of the metal wiring to increase its cross-sectional area, but when using metal wiring flexibly, there are limits to the thickness due to issues such as the strength of the metal wiring. From this perspective as well, R ０ And R is preferably 200 μΩ·cm or less.

[0082] Furthermore, the copper-nickel sintered film of this embodiment can be manufactured, for example, by a method for manufacturing a copper-nickel sintered film that includes the light irradiation step of this embodiment described above.

[0083] The copper-nickel sintered film produced by the method for manufacturing a copper-nickel sintered film, which includes a light irradiation step, has a denser sintered structure, resulting in a higher initial volume resistivity R ０ It has the characteristics of low volume resistivity, suppressing a large increase in the volume resistivity of the sintered film over time, and having high smoothness. These characteristics are due to the fact that the nickel sintered film smoothly coats the surface of the copper sintered film, thereby suppressing the oxidation of copper. In other words, the nickel sintered film suppresses the oxidation of copper during sintering, thereby reducing the initial volume resistivity R ０ This allows us to keep the volume resistivity low, and the nickel sintered film suppresses the oxidation of the copper sintered film over time, thereby preventing a significant increase in volume resistivity over time.

[0084] For example, the initial volume resistivity R of a copper-nickel sintered film produced by the method for producing a copper-nickel sintered film including a light irradiation step according to this embodiment. ０ R may be 200 μΩ·cm or less. Furthermore, when R is the volume resistivity of the copper-nickel sintered film after an accelerated oxidation test in which it is left standing at 180°C for 8 hours in air, R may be 200 μΩ·cm or less. ０ If R is within this range, a sufficient and stable current can be supplied to the copper-nickel sintered film of metal wiring, etc., from the initial stage to long-term normal use. However, if R as a resistance value is large, the metal wiring itself becomes a resistor, which poses a risk of overheating. To prevent this, R can be reduced by increasing the thickness of the metal wiring to increase its cross-sectional area, but when using metal wiring flexibly, there are limits to the thickness due to issues such as the strength of the metal wiring. From this perspective as well, R ０ And R is preferably 200 μΩ·cm or less.

[0085] The present invention will be described in detail below based on examples and comparative examples, but the present invention is not limited in any way by the examples. In the examples and comparative examples, conductive inks were first manufactured, and the physical properties of the manufactured conductive inks and the physical properties of the sintered films formed using the conductive inks were evaluated.

[0086] [Manufacturing of conductive ink] <Example 1> (Manufacturing of copper complex ink) ・Raw materials for copper complex ink The raw materials for copper complex ink are copper(II) formate tetrahydrate (Cu(HClO) ２ 4H ２ O) Powder (manufactured by Fujifilm Wako Pure Chemical Corporation) and 2-amino-2-methyl-1-propanol ((CH ３ ) ２ C(NH ２ )CH ２ Solid material of OH) (AMP, manufactured by Fujifilm Wako Pure Chemical Corporation) was used.

[0087] - Grinding process: Copper(II) formate tetrahydrate was ground using a mortar and pestle until it turned whitish in color.

[0088] - Stirring process: One 20 mm diameter stirrer tip and 4.00 g of 2-amino-2-methyl-1-propanol at 40°C were placed in a 30 mL screw-cap tube, and the mixture was stirred using a hot stirrer at 500 rpm and 40°C. Subsequently, 5.06 g of copper(II) formate tetrahydrate, which had been ground, was added to the screw-cap tube. After stirring for 24 hours, the stirring conditions were changed to 100 rpm and 25°C, and stirring was continued. After a total of 96 hours of stirring, Cu-AMP was obtained as a copper complex.

[0089] (Manufacturing of nickel complex ink) ・Raw materials for nickel complex ink The raw materials for nickel complex ink include nickel(II) formate dihydrate (Ni(HClOO) ２ ・2H ２ O) Powder of (manufactured by Fujifilm Wako Pure Chemical Corporation) and liquid 1-amino-2-propanol (CH ３ C(OH)CH ２ NH ２ (Manufactured by APol Pure Chemical Co., Ltd.) was used.

[0090] - Grinding process: Nickel(II) formate dihydrate was ground using a mortar and pestle until it turned whitish in color.

[0091] - Stirring process: One 20 mm diameter stirrer tip and 6.50 g of 1-amino-2-propanol were placed in a 30 mL screw-cap tube, and the mixture was stirred using a hot stirrer at 500 rpm and a temperature of 25°C. Subsequently, 4.00 g of nickel(II) formate dihydrate, which had been ground, was placed in the screw-cap tube. After stirring for 24 hours, Ni-APol was obtained as a nickel complex.

[0092] (Manufacturing of conductive ink) 0.41 g of manufactured Cu-AMP, 0.22 g of Ni-APol, 5.24 g of copper particles (number average particle size 0.4 μm), and 1.1 g of ethylene glycol (EG, manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer (THINKY ARE-310, manufactured by Thinky Corporation) to obtain the conductive ink of Example 1.

[0093] <Example 2> In the same manner as in Example 1, 0.18 g of Cu-AMP, 0.5 g of Ni-APol, 5.7 g of copper particles (number average particle size 0.4 μm), and 2.0 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 2.

[0094] <Example 3> In the same manner as in Example 1, 0.72 g of Cu-AMP, 0.46 g of Ni-APol, 5.18 g of copper particles (number average particle size 0.4 μm), and 0.65 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 3.

[0095] <Example 4> In the same manner as in Example 1, 2.7 g of Cu-AMP, 0.34 g of Ni-APol, and 3.80 g of copper particles (number average particle size 0.4 μm) were placed in a container and mixed for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 4. Ethylene glycol was not used.

[0096] <Example 5> In the same manner as in Example 1, 0.68 g of Cu-AMP, 0.84 g of Ni-APol, 4.88 g of copper particles (number average particle size 0.4 μm), and 0.61 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 5.

[0097] <Example 6> In the same manner as in Example 1, 0.66 g of Cu-AMP, 1.15 g of Ni-APol, 4.80 g of copper particles (number average particle size 0.4 μm), and 0.60 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 6.

[0098] <Example 7> In the same manner as in Example 1, 0.64 g of Cu-AMP, 1.21 g of Ni-APol, 4.58 g of copper particles (number average particle size 0.4 μm), and 0.57 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 7.

[0099] <Example 8> In the same manner as in Example 1, 0.40 g of Cu-AMP, 1.51 g of Ni-APol, 5.00 g of copper particles (number average particle size 0.4 μm), and 0.36 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 8.

[0100] <Example 9> In the same manner as in Example 1, 0.64 g of Cu-AMP, 1.62 g of Ni-APol, 4.60 g of copper particles (number average particle size 0.4 μm), and 0.14 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 9.

[0101] <Example 10> In the same manner as in Example 1, 0.15 g of Cu-AMP, 1.86 g of Ni-APol, and 4.5 g of copper particles (number average particle size 0.4 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 10. Ethylene glycol was not used.

[0102] <Example 11> In the same manner as in Example 1, 0.58 g of Cu-AMP, 1.73 g of Ni-APol, 4.17 g of copper particles (number average particle size 0.4 μm), and 0.52 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 11.

[0103] <Example 12> In the same manner as in Example 1, 1.50 g of Cu-AMP, 1.64 g of Ni-APol, and 3.8 g of copper particles (number average particle size 0.4 μm) were placed in a container and mixed for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 12. Ethylene glycol was not used.

[0104] <Example 13> In the same manner as in Example 1, 2.30 g of Cu-AMP, 1.47 g of Ni-APol, and 3.23 g of copper particles (number average particle size 0.4 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 13. Ethylene glycol was not used.

[0105] <Example 14> In the same manner as in Example 1, 4.50 g of Cu-AMP, 2.20 g of Ni-APol, and 4.72 g of copper particles (number average particle size 0.4 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 14. Ethylene glycol was not used.

[0106] <Example 15> In the same manner as in Example 1, 0.54 g of Cu-AMP, 2.10 g of Ni-APol, 3.88 g of copper particles (number average particle size 0.4 μm), and 0.48 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 15.

[0107] <Comparative Example 1> In the same manner as in Example 1, 0.69 g of Cu-AMP, 3.65 g of Ni-APol, and 5.00 g of copper particles (number average particle size 0.4 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Comparative Example 1. Ethylene glycol was not used.

[0108] <Example 16> (Copper complex ink) A copper complex ink was manufactured in the same manner as in Example 1.

[0109] (Manufacturing of nickel complex ink) ・Raw materials for nickel complex ink The raw materials for nickel complex ink include nickel(II) formate dihydrate (Ni(HClOO) ２ ・2H ２ O) Powder and liquid DL-2-amino-1-butanol (CH) (manufactured by Fujifilm Wako Pure Chemical Corporation) ３ C(NH ２ )CH ２ OH) (ABol, manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0110] - Grinding process: Nickel(II) formate dihydrate was ground using a mortar and pestle until it turned whitish in color.

[0111] - Stirring process: One 20 mm diameter stirrer tip and 7.70 g of DL-2-amino-1-butanol were placed in a 30 mL screw-cap tube, and the mixture was stirred using a hot stirrer at 500 rpm and a temperature of 25°C. Subsequently, 4.00 g of nickel(II) formate dihydrate, which had been ground, was placed in the screw-cap tube. After stirring for 24 hours, Ni-ABol was obtained as a nickel complex.

[0112] (Manufacturing of conductive ink) 0.41 g of Cu-AMP manufactured in the same manner as in Example 1, 0.24 g of Ni-ABol, 5.22 g of copper particles (number average particle size 0.4 μm), and 1.1 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 16.

[0113] <Example 17> In the same manner as in Example 16, 0.18 g of Cu-AMP, 0.55 g of Ni-ABol, 5.70 g of copper particles (number average particle size 0.4 μm), and 2.00 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 17.

[0114] <Example 18> In the same manner as in Example 16, 0.71 g of Cu-AMP, 0.50 g of Ni-ABol, 5.14 g of copper particles (number average particle size 0.4 μm), and 0.64 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 18.

[0115] <Example 19> In the same manner as in Example 16, 2.60 g of Cu-AMP, 0.37 g of Ni-ABol, and 3.67 g of copper particles (number average particle size 0.4 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 19. Ethylene glycol was not used.

[0116] <Example 20> In the same manner as in Example 16, 0.67 g of Cu-AMP, 0.91 g of Ni-ABol, 4.82 g of copper particles (number average particle size 0.4 μm), and 0.60 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 20.

[0117] <Example 21> In the same manner as in Example 16, 0.66 g of Cu-AMP, 1.30 g of Ni-ABol, 4.80 g of copper particles (number average particle size 0.4 μm), and 0.50 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 21.

[0118] <Example 22> In the same manner as in Example 16, 0.30 g of Cu-AMP, 1.31 g of Ni-ABol, 4.49 g of copper particles (number average particle size 0.4 μm), and 0.56 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 22.

[0119] <Example 23> In the same manner as in Example 16, 0.62 g of Cu-AMP, 1.32 g of Ni-ABol, 4.49 g of copper particles (number average particle size 0.4 μm), and 0.56 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 23.

[0120] <Example 24> In the same manner as in Example 16, 0.14 g of Cu-AMP, 2.00 g of Ni-ABol, and 4.40 g of copper particles (number average particle size 0.4 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 24. Ethylene glycol was not used.

[0121] <Example 25> In the same manner as in Example 16, 0.56 g of Cu-AMP, 1.87 g of Ni-ABol, 4.06 g of copper particles (number average particle size 0.4 μm), and 0.51 g of ethylene glycol were placed in a container and mixed for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 25.

[0122] <Example 26> In the same manner as in Example 16, 1.42 g of Cu-AMP, 1.72 g of Ni-ABol, and 3.60 g of copper particles (number average particle size 0.4 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 26. Ethylene glycol was not used.

[0123] <Example 27> In the same manner as in Example 16, 2.13 g of Cu-AMP, 1.50 g of Ni-ABol, and 3.00 g of copper particles (number average particle size 0.4 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 27. Ethylene glycol was not used.

[0124] <Example 28> In the same manner as in Example 16, 4.50 g of Cu-AMP, 2.45 g of Ni-ABol, 4.72 g of copper particles (number average particle size 0.4 μm), and 0.47 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 28.

[0125] <Example 29> In the same manner as in Example 16, 0.52 g of Cu-AMP, 2.26 g of Ni-ABol, 3.75 g of copper particles (number average particle size 0.4 μm), and 0.47 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 16, to obtain the conductive ink of Example 29.

[0126] <Comparative Example 2> In the same manner as in Example 16, 0.69 g of Cu-AMP, 4.10 g of Ni-ABol, and 5.00 g of copper particles (number average particle size 0.4 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotation-revolution mixer in the same manner as in Example 16 to obtain the conductive ink of Comparative Example 2. Ethylene glycol was not used.

[0127] <Example 30> (Copper complex ink) A copper complex ink was manufactured in the same manner as in Example 1.

[0128] (Manufacturing of nickel complex ink) ・Raw materials for nickel complex ink The raw materials for nickel complex ink include nickel(II) formate dihydrate (Ni(HClOO) ２ ・2H ２ O) Powder of (manufactured by Fujifilm Wako Pure Chemical Corporation) and liquid 2-(methylamino)ethanol (CH ３ NHCH ２ CH ２ OH) (MAEol, manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0129] - Grinding process: Nickel(II) formate dihydrate was ground using a mortar and pestle until it turned whitish in color.

[0130] - Stirring process: One 20 mm diameter stirrer tip and 6.50 g of 2-(methylamino)ethanol were placed in a 30 mL screw-cap tube, and the mixture was stirred using a hot stirrer at 500 rpm and a temperature of 25°C. Subsequently, 4.00 g of nickel(II) formate dihydrate, which had been ground, was placed in the screw-cap tube. After stirring for 24 hours, Ni-MAEol was obtained as a nickel complex.

[0131] (Manufacturing of conductive ink) 0.69 g of Cu-AMP manufactured in the same manner as in Example 1, 2.07 g of Ni-MAEol, 5.00 g of copper particles (number average particle size 0.4 μm), and 0.63 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 30.

[0132] <Example 31> (Copper complex ink) A copper complex ink was manufactured in the same manner as in Example 1.

[0133] (Manufacturing of nickel complex ink) ・Raw materials for nickel complex ink The raw materials for nickel complex ink include nickel(II) formate dihydrate (Ni(HClOO) ２ ・2H ２ O) Powder and liquid 2-aminoethanol (NH) (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) ２ CH ２ CH ２ OH) (AEol, manufactured by Tokyo Chemical Industry Co., Ltd.) was used.

[0134] - Grinding process: Nickel(II) formate dihydrate was ground using a mortar and pestle until it turned whitish in color.

[0135] - Stirring process: One 20 mm diameter stirrer tip and 5.30 g of 2-aminoethanol were placed in a 30 mL screw-cap tube, and the mixture was stirred using a hot stirrer at 500 rpm and a temperature of 25°C. Subsequently, 4.00 g of nickel(II) formate dihydrate, which had been ground, was added to the screw-cap tube. After stirring for 24 hours, Ni-AEol was obtained as a nickel complex.

[0136] (Manufacturing of conductive ink) 0.69 g of Cu-AMP manufactured in the same manner as in Example 1, 1.83 g of Ni-AEol, 5.00 g of copper particles (number average particle size 0.4 μm), and 0.63 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 31.

[0137] <Comparative Example 3> (Copper Complex Ink) A copper complex ink was manufactured in the same manner as in Example 1.

[0138] (Manufacturing of nickel complex ink) ・Raw materials for nickel complex ink The raw materials for nickel complex ink include nickel(II) formate dihydrate (Ni(HClOO) ２ ・2H ２ O) Powder and liquid 2-ethylhexylamine (CH) (manufactured by Fujifilm Wako Pure Chemical Corporation) ３ CH ２ CH ２ CH ２ CH ２ (CH ２ CH ３ )CH ２ NH ２ (2EHA manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) and ethylene glycol (manufactured by Fujifilm Wako Pure Chemical Industries, Ltd.) were used.

[0139] - Grinding process: Nickel(II) formate dihydrate was ground using a mortar and pestle until it turned whitish in color.

[0140] - Stirring process: One 20 mm diameter stirrer tip, 1.0 g of ethylene glycol, and 5.6 g of 2-ethylhexylamine were placed in a 30 mL screw-cap tube, and the mixture was stirred using a hot stirrer at 500 rpm and a temperature of 25°C. Subsequently, 4.00 g of nickel(II) formate dihydrate, which had been ground, was added to the screw-cap tube. After stirring for 24 hours, 2-ethylhexylamine was added as a ligand to nickel(II) formate (Ni(HClO)). ２ (HCOO) is coordinated to two molecules. ２ Ni(CH ３ CH ２ CH ２ CH ２ CH ２ (CH ２ CH ３ )CH ２ NH ２ ) ２ A nickel complex represented by (sometimes referred to as "Ni-2EHA") was obtained.

[0141] (Manufacturing of conductive ink) 11.0 g of Cu-AMP, manufactured in the same manner as in Example 1, and 1.00 g of Ni-2EHA were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Comparative Example 3. Copper particles were not used, and ethylene glycol was not newly added in the manufacturing of the conductive ink.

[0142] <Comparative Example 4> Cu-AMP manufactured in the same manner as in Example 1 was used as the conductive ink for Comparative Example 4. Nickel complex, copper particles, and ethylene glycol were not used in the conductive ink of Comparative Example 4.

[0143] <Comparative Example 5> 0.58 g of Cu-AMP produced in the same manner as in Example 1, 1.75 g of Ni-2EHA produced in the same manner as in Comparative Example 3, 4.17 g of copper particles (number average particle size 0.4 μm), and 0.52 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer in the same manner as in Example 1 to obtain the conductive ink of Comparative Example 5.

[0144] <Comparative Example 6> 0.58 g of Cu-AMP produced in the same manner as in Example 1, 1.75 g of Ni-2EHA produced in the same manner as in Comparative Example 3, 4.17 g of copper particles (number average particle size 0.4 μm), and 2.60 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Comparative Example 6. The conductive ink of Comparative Example 6 corresponds to the conductive ink of Comparative Example 5 diluted with ethylene glycol.

[0145] <Comparative Example 7> 1.10 g of Cu-AMP produced in the same manner as in Example 1, 3.30 g of Ni-2EHA produced in the same manner as in Comparative Example 3, and 1.00 g of copper particles (number average particle size 0.4 μm) were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Comparative Example 7. No ethylene glycol was newly added in the production of the conductive ink.

[0146] <Comparative Example 8> 0.46 g of Cu-AMP prepared in the same manner as in Example 1, 5.8 g of copper particles (number average particle size 0.4 μm), and 1.20 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Comparative Example 8. The conductive ink of Comparative Example 8 is an ink that does not contain a nickel complex.

[0147] Tables 1-1 to 1-3 show the composition, copper ratio, and nickel ratio of the conductive inks for Examples 1 to 31 and Comparative Examples 1 to 8. In Tables 1-1 to 1-3, the copper ratio is the ratio of copper contained in the copper complex to the total amount of copper contained in the copper particles and the copper complex, and the nickel ratio is the ratio of nickel contained in the nickel complex to the total amount of copper contained in the copper particles and the copper complex and the nickel contained in the nickel complex.

[0148]

[0149]

[0150]

[0151] [Evaluation of physical properties using conductive ink] The following physical properties were evaluated using the conductive inks of Examples 1 to 31 and Comparative Examples 1 to 8 that were manufactured.

[0152] <Viscosity Measurement of Conductive Ink> Viscosity was measured using an Anton Paar MCR302e rheometer with a φ25 mm disposable parallel plate. The gap between the upper and lower plates was fixed at 0.2 mm, and the shear rate was set to 0.01 sec. －１ from 100 seconds －１ The shear viscosity was measured while increasing the viscosity up to a certain point. From the obtained flow curve, it was determined that the shear rate was 0.1 / s (0.1 sec). －１ When viscosity and shear rate are 10 / s (10 sec) in the case of ) －１ The viscosity was read in the case of ).

[0153] [Physical properties of sintered films] Sintered films were manufactured using the conductive inks of Examples 1 to 31 and Comparative Examples 1 to 8, and their volume resistivity was measured.

[0154] <Manufacturing of Sintered Film> Using a mesh capable of forming electrode wiring patterns by screen printing, conductive ink was printed onto a 50 μm thick polyimide film substrate in the shape of a line width of 2000 μm and a length of 14 mm to form a coated film. This coated film was placed in a reflow oven and heated from room temperature to 200°C at a heating rate of 10°C / min under a nitrogen atmosphere, and then held at 200°C for 10 minutes to obtain a heat-treated sintered film. After that, it was allowed to cool under a nitrogen atmosphere and removed from the reflow oven.

[0155] <Measurement of volume resistivity> (Initial volume resistivity R) ０ (Measurement) A HIOKI RM3548 resistance meter was used as the resistance meter, and pin-type leads were used as electrode terminals, with measurements taken using the four-terminal method. The resistance value of the sintered film was measured by contacting both ends of the sintered film within one day of manufacture with the electrode terminals, and the obtained "resistance value × width of sintered film × thickness of sintered film ÷ length of sintered film" was calculated to determine the initial volume resistivity R ０ The result was calculated.

[0156] (Measurement of volume resistivity R after accelerated oxidation test) Initial volume resistivity R ０After measuring the initial volume resistivity R, the sintered film was subjected to an accelerated oxidation test by standing it at 180°C in air for 8 hours, and the subsequent volume resistivity R was compared to the initial volume resistivity R. ０ It was measured using the same method as the previous measurement.

[0157] <Surface Roughness Measurement> (Arithmetic Mean Roughness Ra) The arithmetic mean roughness Ra of the fabricated sintered film was measured using a stylus-type scanning meter, SURFCOM TOUCH 50, manufactured by Tokyo Seimitsu Co., Ltd.

[0158] Tables 2-1 to 2-3 show the viscosity of the conductive ink and the initial volume resistivity R of the sintered film in Examples 1 to 31 and Comparative Examples 1 to 8. ０ Volume resistivity R, R / R after accelerated oxidation test ０ The measurement results for surface roughness Ra are shown.

[0159]

[0160]

[0161]

[0162] (Results) The sintered films of Examples 1 to 31 had an initial volume resistivity R ０ Furthermore, the volume resistivity R after the accelerated oxidation test was low, at 200 μΩ·cm or less. Also, as a guideline for observing the change in volume resistivity, Tables 2-1 to 2-3 show the R / R ratio. ０ This was shown.

[0163] R / R ０ The closer the value is to 1, the less the change in volume resistivity over time. If the volume resistivity R after the oxidation-accelerated test is 200 μΩ·cm or less, then R / R ０ R / R of sintered films of Examples 1 to 31 is acceptable even if it is 6 or less, and is more preferable if it is 4 or less, 3 or less, or 2 or less. ０ All of them were 6 or less.

[0164] Furthermore, while a surface roughness Ra of 1 μm or less is a guideline, the results in Tables 2-1 to 2-3 show that there were no problems with the smoothness of the sintered films in Examples 1 to 31.

[0165] Furthermore, the viscosity of the conductive inks in Examples 1 to 31 was 1.0 Pa·s to 1000.0 Pa·s at a shear rate of 0.1 / s, and 1.0 Pa·s to 100.0 Pa·s at a shear rate of 10 / s, which were all good results.

[0166] The sintered films of Comparative Examples 1 and 2, in which the nickel content exceeds 7% by mass, have an initial volume resistivity R ０ Both the initial volume resistivity R after the oxidation acceleration test exceeded 200 μΩ·cm. Furthermore, the sintered film of Comparative Example 4, which used only the copper complex Cu-AMP, the sintered films of Comparative Examples 6 and 7, which used Ni-2EHA as the nickel complex, and the sintered film of Comparative Example 8, which used conductive ink without a nickel complex, all showed an initial volume resistivity R ０ The volume resistivity R after the oxidation-accelerated test exceeded 200 μΩ·cm.

[0167] [Physical Properties of Sintered Films with Different Wiring Widths] Figures 1A to 6B show optical microscope images of the surface of metal wiring with widths ranging from 30 μm to 2000 μm, formed by screen printing using conductive inks from Examples 5, 11, 20, 25, and Comparative Examples 5 and 7, along with the results of measuring the cross-sectional thickness. The metal wiring was formed as follows.

[0168] (Formation of Metal Wiring) Using a mesh capable of forming electrode wiring patterns by screen printing, conductive ink was printed onto a polyimide film substrate in the shape of line widths of 30 μm, 100 μm, 200 μm, and 2000 μm with a length of 30 mm to form a coated film. This coated film was set in a reflow oven and heated from room temperature to 200°C at a heating rate of 5°C / min under a nitrogen atmosphere, and then held at 200°C for 10 minutes to obtain a sintered film of metal wiring. After that, it was allowed to cool under a nitrogen atmosphere and removed from the reflow oven, and optical microscope images of the obtained metal wiring were taken, and the thickness was measured using a stylus-type scanning meter, SURFCOM TOUCH 50, manufactured by Tokyo Seimitsu Co., Ltd.

[0169] (Results) The metal wiring in Examples 5, 11, 20, and 25 all had a thickness within the range of 2 μm to 9 μm, and no defects such as uneven color, breaks, or uneven wire width were observed, indicating that the metal wiring was of good quality. Figures 1A to 4B show the results for Examples 5, 11, 20, and 25, but similarly good metal wiring was obtained in the other examples as well.

[0170] The optical microscope images (2) in Figures 5A and 5B, which show the results for Comparative Example 5, are enlarged versions of the optical microscope images (1) for the 30 μm, 100 μm, and 200 μm widths, while the 2000 μm width image is a photograph of a different part than the optical microscope image (1). In Comparative Example 5, the 30 μm width metal wiring was broken, making it impossible to measure the cross-section. The 100 μm and 200 μm width wirings showed areas where the width narrowed, and the 2000 μm width wiring showed bulging, indicating poor metal wiring formation in all cases.

[0171] Furthermore, it was suspected that the poor formation of the metal wiring was due to the high viscosity of the conductive ink in Comparative Example 5. Therefore, screen printing was performed using the conductive ink of Comparative Example 6, which is equivalent to the conductive ink of Comparative Example 5 diluted with ethylene glycol. However, the results were the same as in Comparative Example 5, with poor formation of the metal wiring still observed, and the printing characteristics did not improve.

[0172] The photographs in the optical microscope images (2) in Figures 6A and 6B, which show the results for Comparative Example 7, are enlarged versions of the optical microscope image (1) for the 30 μm, 100 μm, and 200 μm widths, and a photograph of a different part from the optical microscope image (1) for the 2000 μm width. In Comparative Example 7, the 30 μm width metal wiring was broken, and cross-sectional measurement was not possible. For the 100 μm and 200 μm width wirings, color unevenness was observed on the surface of the wiring, and for the 2000 μm width wiring, blistering occurred and then ruptured, indicating poor metal wiring formation in all cases.

[0173] In Comparative Examples 1, 2, and 8, although good metal wiring was obtained similarly to Examples 1 to 31, the volume resistivity was high, as shown in Tables 2-1 to 2-3. In Comparative Examples 3 and 4, since the conductive ink did not contain copper particles, thin metal wiring with a thickness of less than 1 μm was formed.

[0174] [Evaluation of physical properties of copper-nickel sintered films sintered under different sintering temperatures] Conductive ink was sintered under different sintering temperatures, and the volume resistivity of the resulting copper-nickel sintered films was measured.

[0175] [Manufacturing of conductive ink] <Example 32> 0.32 g of Cu-AMP, 0.43 g of Ni-APol, 5.00 g of copper particles (number average particle size 0.4 μm), and 0.9 g of ethylene glycol, prepared in the same manner as in Example 1, were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 32.

[0176] <Example 33> In the same manner as in Example 1, 0.32 g of Cu-AMP, 1.30 g of Ni-APol, 5.00 g of copper particles (number average particle size 0.4 μm), and 0.5 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 33.

[0177] <Example 34> The same conductive ink as in Example 33 was manufactured.

[0178] <Example 35> The same conductive ink as in Example 33 was manufactured.

[0179] <Example 36> In the same manner as in Example 1, 0.32 g of Cu-AMP, 2.05 g of Ni-APol, 5.00 g of copper particles (number average particle size 0.4 μm), and 0.15 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 36.

[0180] <Example 37> The same conductive ink as in Example 36 was manufactured.

[0181] <Example 38> The same conductive ink as in Example 36 was manufactured.

[0182] Table 3 shows the composition, copper ratio, and nickel ratio of the conductive inks for Examples 32 to 38. In Table 3, the copper ratio is the ratio of copper in the copper complex to the total amount of copper in the copper particles and copper complex, and the nickel ratio is the ratio of nickel in the nickel complex to the total amount of copper in the copper particles and copper complex and nickel in the nickel complex. The heat treatment temperature during sintering, which will be described later, is also shown.

[0183]

[0184] [Physical properties of sintered films] Sintered films were manufactured using the conductive inks of Examples 32 to 38, and their volume resistivity R was measured.

[0185] <Manufacturing of Sintered Film> Using a mesh capable of forming electrode wiring patterns by screen printing, conductive ink was printed onto a 50 μm thick polyimide film substrate in the shape of a line width of 2000 μm and a length of 14 mm to form a coated film. This coated film was placed in a reflow oven and heated from room temperature to 160°C and 250°C respectively at a heating rate of 10°C / min under a nitrogen atmosphere, and then held at 160°C and 250°C respectively for 10 minutes to obtain a heat-treated sintered film. After that, it was allowed to cool under a nitrogen atmosphere and removed from the reflow oven.

[0186] <Measurement of volume resistivity> (Initial volume resistivity R) ０ (Measurement) A HIOKI RM3548 resistance meter was used as the resistance meter, and pin-type leads were used as electrode terminals, with measurements taken using the four-terminal method. The resistance value of the sintered film was measured by contacting both ends of the sintered film within one day of manufacture with the electrode terminals, and the obtained "resistance value × width of sintered film × thickness of sintered film ÷ length of sintered film" was calculated to determine the initial volume resistivity R ０ The result was calculated.

[0187] (Measurement of volume resistivity R after accelerated oxidation test) Initial volume resistivity R ０ After measuring the initial volume resistivity R, the sintered film was subjected to an accelerated oxidation test by standing it at 180°C in air for 8 hours, and the subsequent volume resistivity R was compared to the initial volume resistivity R. ０ It was measured using the same method as the previous measurement.

[0188] Table 4 shows the heat treatment temperature during sintering and the initial volume resistivity R of the sintered film in Examples 32 to 38. ０ Volume resistivity R, R / R after accelerated oxidation test ０ The measurement results are shown below.

[0189]

[0190] (Results) The sintered films of Examples 32 to 38 had an initial volume resistivity R ０ Furthermore, the volume resistivity R after the oxidation acceleration test was low, at 200 μΩ·cm or less, and R / R ０ All values ​​were 6 or less. These results indicate that a sintered film with low volume resistivity and good conductivity can be obtained by setting the sintering temperature to 160°C to 250°C.

[0191] [Evaluation of Physical Properties of Copper-Nickel Sintered Films Using Two Types of Copper Particles] Conductive inks were prepared using two types of copper particles with different number-average particle sizes, and the volume resistivity of copper-nickel sintered films formed using these conductive inks was measured. For comparison, the results of Example 35, which used one type of copper particle with a number-average particle size of 0.4 μm, are also shown in Tables 5 and 6.

[0192] (Copper particles) As for the copper particles, we used copper particles with a number-average particle diameter of 0.4 μm, as described above, and newly, copper particles with a number-average particle diameter of 0.2 μm.

[0193] [Manufacturing of conductive ink] <Example 39> 0.32 g of Cu-AMP manufactured in the same manner as in Example 1, 1.30 g of Ni-APol, 4.25 g of copper particles (number average particle size 0.4 μm), 0.75 g of copper particles (number average particle size 0.2 μm), and 0.5 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 39.

[0194] <Example 40> In the same manner as in Example 1, 0.32 g of Cu-AMP, 1.30 g of Ni-APol, 3.75 g of copper particles (number average particle size 0.4 μm), 1.25 g of copper particles (number average particle size 0.2 μm), and 0.5 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 40.

[0195] <Example 41> In the same manner as in Example 1, 0.32 g of Cu-AMP, 1.30 g of Ni-APol, 3.00 g of copper particles (number average particle size 0.4 μm), 2.00 g of copper particles (number average particle size 0.2 μm), and 0.5 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 41.

[0196] Table 5 shows the composition, copper ratio, and nickel ratio of the conductive inks for Examples 35, 39-41. In Table 5, the copper ratio is the ratio of copper in the copper complex to the total amount of copper in the copper particles and copper complex, and the nickel ratio is the ratio of nickel in the nickel complex to the total amount of copper in the copper particles and copper complex and nickel in the nickel complex.

[0197]

[0198] [Physical properties of sintered films] Sintered films were manufactured using the conductive inks of Examples 35, 39-41, and their volume resistivity was measured.

[0199] <Manufacturing of Sintered Film> Using a mesh capable of forming electrode wiring patterns by screen printing, conductive ink was printed onto a 50 μm thick polyimide film substrate in the shape of a line width of 2000 μm and a length of 14 mm to form a coated film. This coated film was placed in a reflow oven and heated from room temperature to 250°C at a heating rate of 10°C / min under a nitrogen atmosphere, and then held at 250°C for 10 minutes to obtain a heat-treated sintered film. After that, it was allowed to cool under a nitrogen atmosphere and removed from the reflow oven.

[0200] <Measurement of volume resistivity> (Initial volume resistivity R) ０(Measurement) A HIOKI RM3548 resistance meter was used as the resistance meter, and pin-type leads were used as electrode terminals, with measurements taken using the four-terminal method. The resistance value of the sintered film was measured by contacting both ends of the sintered film within one day of manufacture with the electrode terminals, and the obtained "resistance value × width of sintered film × thickness of sintered film ÷ length of sintered film" was calculated to determine the initial volume resistivity R ０ The result was calculated.

[0201] (Measurement of volume resistivity R after accelerated oxidation test) Initial volume resistivity R ０ After measuring the initial volume resistivity R, the sintered film was subjected to an accelerated oxidation test by standing it at 180°C in air for 8 hours, and the subsequent volume resistivity R was compared to the initial volume resistivity R. ０ It was measured using the same method as the previous measurement.

[0202] Table 6 shows the heat treatment temperature during sintering and the initial volume resistivity R of the sintered film in Examples 35, 39-41. ０ Volume resistivity R, R / R after accelerated oxidation test ０ The measurement results are shown below.

[0203]

[0204] (Results) The sintered films of Examples 39 to 41 had an initial volume resistivity R similar to that of the sintered film of Example 35. ０ Furthermore, the volume resistivity R after the oxidation acceleration test was low, at 200 μΩ·cm or less, and R / R ０ All values ​​were 6 or less. These results indicate that a sintered film with low volume resistivity and good conductivity can be obtained by setting the sintering temperature to 160°C to 250°C.

[0205] Furthermore, by using two types of copper particles with different number-average particle sizes, as in Examples 39 to 41, the initial volume resistivity R is increased compared to Example 35, which uses only one type of copper particle. ０ In both cases, the resistivity was found to be lower in the volume resistivity R after the oxidation-accelerated test.

[0206] [Evaluation of physical properties of copper-nickel sintered films sintered by light irradiation] Below, copper-nickel sintered films formed using conductive ink were irradiated with light, and the volume resistivity of the resulting copper-nickel sintered films was measured.

[0207] [Manufacturing of conductive ink] <Example 42> 0.32 g of Cu-AMP manufactured in the same manner as in Example 1, 1.50 g of Ni-APol, 5.00 g of copper particles (number average particle size 0.4 μm), and 0.5 g of ethylene glycol were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 42.

[0208] <Example 43> In the same manner as in Example 1, 0.99 g of Cu-AMP, 1.50 g of Ni-APol, 5.00 g of copper particles (number average particle size 0.4 μm), and 0.5 g of ethylene glycol were placed in a container, and the mixture was kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 43.

[0209] <Example 44> In the same manner as in Example 1, 2.04 g of Cu-AMP, 1.50 g of Ni-APol, and 5.00 g of copper particles (number average particle size 0.4 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 44. Ethylene glycol was not used.

[0210] <Example 45> In the same manner as in Example 1, 2.04 g of Cu-AMP, 1.35 g of Ni-APol, 3.00 g of copper particles (number average particle size 0.4 μm), and 2.00 g of copper particles (number average particle size 0.2 μm) were placed in a container and kneaded for 6 minutes at a rotation speed of 2000 rpm using a rotary-orbit mixer, as in Example 1, to obtain the conductive ink of Example 45. Ethylene glycol was not used.

[0211] <Example 46> The conductive ink of Example 46 was obtained under the same conditions as in Example 45.

[0212] Table 7 shows the composition, copper ratio, and nickel ratio of the conductive inks for Examples 42 to 46. In Table 7, the copper ratio is the ratio of copper in the copper complex to the total amount of copper in the copper particles and copper complex, and the nickel ratio is the ratio of nickel in the nickel complex to the total amount of copper in the copper particles and copper complex and nickel in the nickel complex.

[0213]

[0214] [Physical Properties of Sintered Films] Sintered films were manufactured using the conductive inks of Examples 42 to 46, and further sintered films were produced by irradiating the sintered films with light. The volume resistivity of these films was then measured.

[0215] <Manufacturing of Sintered Films> Using a mesh capable of forming electrode wiring patterns by screen printing, conductive ink was printed onto a 50 μm thick polyimide film substrate in the shape of lines with a width of 2000 μm and a length of 14 mm to form a coated film. This coated film was placed in a reflow oven and heat-treated under a nitrogen atmosphere by raising the temperature from room temperature to 250°C at a heating rate of 10°C / min, and then holding at 250°C for 10 minutes to obtain the sintered films of Examples 42 to 46. After that, the films were allowed to cool under a nitrogen atmosphere and removed from the reflow oven.

[0216] <Manufacturing of sintered film including light irradiation process> Using a XENON S-2210 (manufactured by XENON Corporation), the manufactured sintered film was irradiated once with a xenon flash lamp to perform light irradiation. For the sintered films of Examples 42 to 45, the conditions for light irradiation were a distance of 160 mm between the sintered film and the flash lamp, a voltage of 3000 V, and a pulse width of 300 μs. For the sintered film of Example 46, the conditions for light irradiation were a distance of 160 mm between the sintered film and the flash lamp, a voltage of 2100 V, and a pulse width of 300 μs.

[0217] <Measurement of volume resistivity> (Initial volume resistivity R) ０ (Measurement) A HIOKI RM3548 resistance meter was used as the resistance meter, and pin-type leads were used as electrode terminals, with measurements performed using the four-terminal method. The electrode terminals were brought into contact with both ends of the sintered film immediately after manufacturing and before the light irradiation process, and the resistance values ​​of these sintered films were measured. The initial volume resistivity R of the sintered film immediately after manufacturing and before the light irradiation process was calculated by formulating "resistivity value × width of sintered film × thickness of sintered film ÷ length of sintered film". ０ The result was calculated.

[0218] (Measurement of volume resistivity R of sintered film after accelerated oxidation test) Initial volume resistivity R ０After measuring the initial volume resistivity R of the sintered film immediately following the light irradiation process, an accelerated oxidation test was performed by leaving the film standing at 180°C in air for 48 hours. ０ It was measured using the same method as the previous measurement.

[0219] Table 8 shows the heat treatment temperature during sintering in Examples 42-46, and the initial volume resistivity R of the sintered film immediately after manufacturing and before the light irradiation process. ０ The initial volume resistivity R of the sintered film immediately after the light irradiation process. ０ , and the volume resistivity R of the sintered film after the accelerated oxidation test, and the R / R of the sintered film after the light irradiation process. ０ The measurement results are shown below.

[0220]

[0221] (Results) In Examples 42 to 46, the initial volume resistivity R of the sintered film immediately after manufacturing and before the light irradiation process was ０ The initial volume resistivity R of the sintered film immediately after the light irradiation process. ０ The volume resistivity R after the oxidation acceleration test was low, at 200 μΩ·cm or less. Furthermore, the R / R ratio after the light irradiation process was also low. ０ All of these values ​​were 6 or less. From these results, it was found that in Examples 42 to 46, a sintered film with low volume resistivity and good conductivity can be obtained.

[0222] Furthermore, in all of Examples 42 to 46, the volume resistivity of the sintered film subjected to the light irradiation process was lower than that of the sintered film not subjected to the light irradiation process, and even after the accelerated oxidation test, the volume resistivity remained lower than the initial value of the sintered film. These results indicate that by performing the light irradiation process, a sintered film with lower resistivity and superior oxidation resistance can be obtained.

Claims

1. The material comprises copper particles, a copper complex, and a nickel complex, wherein the copper complex is Cu(HClO) ２ (L) ｍ The complex is represented by Ni(HCOO) ２ (L) ｎ A conductive ink comprising a complex represented by , wherein L is at least one selected from 2-amino-2-methyl-1-propanol, 1-amino-2-propanol, 2-amino-1-butanol, 2-(methylamino)ethanol, and 2-aminoethanol, m is a natural number from 2 to 6, n is a natural number from 2 to 6, the ratio of copper contained in the copper complex to the total amount of copper contained in the copper particles and the copper complex is 0.5% by mass to 15.0% by mass, and the ratio of nickel contained in the nickel complex to the total amount of copper contained in the copper particles and the copper complex and the nickel contained in the nickel complex is 0.5% by mass to 7.0% by mass.

2. The conductive ink according to claim 1, wherein the ratio of nickel contained in the nickel complex to the total amount of copper contained in the copper particles and the copper complex and nickel contained in the nickel complex is 0.5% by mass to 4.7% by mass.

3. The conductive ink according to claim 1, wherein the number-average particle diameter of the copper particles is 0.03 μm to 0.6 μm.

4. The conductive ink according to claim 1, wherein the copper particles include at least two types of copper particles having different number-average particle diameters, and when the total mass of the copper particles with a large number-average particle diameter is W1 and the total mass of the copper particles with a small number-average particle diameter is W2, the mass ratio is W1:W2 = 60 to less than 100: greater than 0 to 40.

5. The conductive ink according to claim 1, wherein the shear viscosity at a shear rate of 0.1 / s is 1.0 Pa·s to 1000.0 Pa·s, and the shear viscosity at a shear rate of 10 / s is 1.0 Pa·s to 100.0 Pa·s.

6. The conductive ink according to claim 1, comprising an organic solvent.

7. A method for producing a copper-nickel sintered film, comprising a sintering step of heating the conductive ink described in claim 1 to sinter the conductive ink, wherein a nickel sintered film is coated on the surface of a copper sintered film, and the ratio of nickel to the total of copper and nickel is 0.5% by mass to 7.0% by mass.

8. A method for manufacturing a copper-nickel sintered film according to claim 7, comprising a coating step of applying the conductive ink described in claim 1 to a substrate before the sintering step.

9. The method for producing a copper-nickel sintered film according to claim 8, comprising a drying step of drying the conductive ink after the coating step at 80°C to 120°C, wherein the sintering step is a step of sintering the conductive ink by heating at 160°C to 250°C.

10. A method for manufacturing a copper-nickel sintered film, comprising a light irradiation step of irradiating the copper-nickel sintered film after the sintering step described in claim 7 with light.

11. A copper-nickel sintered film in which a nickel-sintered film is coated on the surface of a copper-sintered film, wherein the ratio of nickel to the total amount of copper and nickel is 0.5% by mass to 7.0% by mass.

12. Initial volume resistivity R of the copper-nickel sintered film ０ The copper-nickel sintered film according to claim 11, wherein the impedance is 200 μΩ·cm or less.

13. The copper-nickel sintered film according to claim 12, wherein R is 200 μΩ·cm or less, when R is the volume resistivity after an accelerated oxidation test in which the film is left standing at 180°C for 8 hours in air.

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