JP2017186605A - Copper paste composition for laser etching - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a copper paste composition for laser etching capable of obtaining a copper cured film having high conductivity by coating and heating (sintering) and exhibiting excellent oxidation resistance even when laser-etching the copper cured film to form a fine cupper wiring having high conductivity.SOLUTION: The copper paste composition for laser etching comprises: surface coated copper particles (A) including a first coating layer formed of an amine compound shown by the formula (1) and a second coating layer formed of aliphatic monocarboxylic acid bonded to the amine compound by chemical bonding on the first coating layer; a binder (B); an antioxidant (C) and a solvent (D). Raw material copper particles for (A) before surface coating has the average particle size D50 of 0.5- 2 μm, and the content of particles having a particle size of 3 μm in the raw material copper particles is 5 mass% or less. [where, in the formula (1), m is an integer of 0-3, n is an integer of 0-2, m is any of 0-3 when n=0, and m is any of 1-3 when n=1 or n=2.]SELECTED DRAWING: None

Description

  TECHNICAL FIELD The present invention relates to a copper paste composition for laser etching capable of obtaining a fine copper wiring having high conductivity by laser etching.

  Conventionally, in the field of electronic materials, etc., a conductive composition mainly composed of a conductive metal as a means of ensuring electrical continuity such as circuit formation for printed wiring boards, lead wiring for touch panels, and various electrical joints. Things are widely used. Silver is frequently used as the conductive metal in the conductive composition because of its excellent oxidation resistance and low volume resistivity. Here, the conductive composition is a fluid composition such as a silver paste described in Patent Document 1, for example. A pattern is drawn by a printing technique, and light or heat is applied. Curing is performed to form conductive wiring. The lower limit of the width of the wiring that can be formed is 50 μm (L / S = 50/50 μm) for the width of the line (L) and the space (S) in the conventional screen printing method. The relationship between the widths of L and S is similarly expressed), and it is generally difficult to form finer wiring with a higher density.

However, with the recent progress of downsizing and larger screens of mobile electronic devices, there is a demand for higher density of conductive wiring in the device, wiring finer than L / S = 50/50 μm, Therefore, there is a demand for a wiring of about L / S = 30/30 μm or less. In order to cope with such a situation, a method of processing a wiring by laser light called laser etching is spreading.
Patent Document 2 discloses a silver paste for laser etching containing a photothermally convertible carbon filler having a predetermined particle diameter and silver particles having an average particle diameter of 5 nm to 30 μm. It is described that the conductive wiring of L / S = about 30/30 μm having high conductivity was formed by processing the film with a solid UV laser (wavelength 355 nm).
Patent Document 3 discloses a conductive paste for laser etching containing metal particles having a center diameter of 80 nm to 4 μm, a binder resin, and an organic solvent, and is excellent in workability and conductivity in laser etching. It is described. However, the metal particles used in Patent Document 3 are only silver particles.

On the other hand, silver has a problem that it is expensive and is likely to cause migration. Therefore, in recent years, it has been studied to use copper having a low volume resistivity, low cost, and excellent migration resistance as a conductive composition next to silver. ing. For example, Patent Document 4 is obtained by dispersing copper particles having an average particle size of 0.5 to 20 μm pretreated with aliphatic polycarboxylic acids in a dispersion medium and reducing the pH at 3 or less and an oxidation-reduction potential of 100 to 300 mV. A copper paste using surface-modified copper particles is disclosed.
However, the copper particles used in the copper paste are easily oxidized, and copper oxide having a high volume resistivity is likely to be generated on the particle surface, which is not a material suitable for severe processing conditions such as laser etching.

JP 2011-246498 A Japanese Patent Application Laid-Open No. 2015-115314 International Publication No. 2014/013899 JP 2011-017067 A

  The object of the present invention is to obtain a copper cured film having high conductivity by applying heat (firing) processing, and exhibiting excellent oxidation resistance even during laser etching of the copper cured film, thereby providing high conductivity. An object of the present invention is to provide a copper paste composition for laser etching that can form a fine copper wiring.

As a result of intensive studies, the inventors of the present invention applied a specific coating agent to a surface of a copper particle having a specific particle diameter by using a specific coating method, thereby curing copper having high conductivity by coating and baking. It was found that a film can be formed, and in particular, fine copper wiring having high conductivity can be obtained by laser etching, and the present invention has been completed.
That is, according to this invention, it is a copper paste composition containing surface-coated copper particles (A), a binder (B), an antioxidant (C), and a solvent (D), and the surface-coated copper particles (A) The raw material copper particles before surface coating have an average particle diameter D50 of 0.5 to 2 μm, and the content of particles having a particle diameter of 3 μm or more in the raw material copper particles is 5% by mass or less. The copper particles (A) are a first coating layer of an amine compound represented by the formula (1) that is bonded to copper on the surface of the raw material copper particles by a chemical bond and / or a physical bond, and the first coating layer. And a second coating layer of an aliphatic monocarboxylic acid having 8 to 20 carbon atoms bonded to the amine compound by a chemical bond, and the copper paste composition comprises the surface-coated copper particles (A) The binder (B) 10-3 with respect to 100 parts by mass There is provided a copper paste composition for laser etching containing 0 part by mass, 0.1 to 7.0 parts by mass of the antioxidant (C), and 1 to 30 parts by mass of the solvent (D).
[In the formula (1), m is an integer of 0 to 3, n is an integer of 0 to 2, and when n = 0, m is any of 0 to 3, when n = 1 or n = 2, m is any one of 1-3. ]

The copper paste composition for laser etching of the present invention is excellent in fine wiring processing by laser etching because the particle diameter of the raw material copper particles of the surface-coated copper particles (A), which is the component thereof, is specified. Hereinafter, unless otherwise specified, the term “copper particles” refers to raw material copper particles.
Furthermore, since the surface-coated copper particles (A) have a first coating layer of an amine compound and a second coating layer of a specific aliphatic monocarboxylic acid, the surface of the copper particles is not easily oxidized during laser etching. Since it has extremely excellent oxidation resistance, fine wiring having high conductivity can be formed by laser etching.

It is a figure showing the IR spectrum measurement result of the particle | grain surface of surface-coated copper particle (A). It is a figure showing IR spectrum measurement result of ethylenediamine. It is a figure which shows the optical microscope image of the copper cured film formed using the copper paste composition for laser etching obtained in Example 1. FIG. It is a figure which shows the optical microscope image of the copper wiring (L / S = 30.2 / 9.8 micrometers) formed by carrying out the laser etching process of the copper cured film shown in FIG. It is a figure which shows the optical microscope image of the copper cured film formed using the copper paste composition obtained by the comparative example 1. FIG. It is a figure which shows the optical microscope image of the copper wiring (L / S = 23.4 / 16.6micrometer) formed by carrying out the laser etching process of the copper cured film shown in FIG.

Hereinafter, embodiments of the present invention will be described in detail.
<Constituent components of copper paste composition for laser etching>
[Surface-coated copper particles (A); hereinafter simply referred to as (A)]
The copper particles before surface coating for (A) have an average particle diameter D50 of 0.5 to 2 μm, and the content of particles having a particle diameter of 3 μm or more in the copper particles is 5 mass% or less. D50 is preferably 1.0 μm or more and 1.5 μm or less. The smaller the average particle size, the easier it is for organic components having a higher laser absorption rate, such as a binder resin, to enter between the copper particles in the cured copper film, and the laser etching processability is improved. However, on the other hand, the specific surface area of the particles increases and the surface of the particles is likely to be covered by non-conductive copper oxide due to oxidation, which may reduce the conductivity of the wiring to be formed. Therefore, if D50 is less than 0.5 μm, the conductivity of the wiring may be lowered, and if it exceeds 2 μm, the laser etching processability may be lowered. For the same reason, when the content of particles having a particle diameter of 3 μm or more exceeds 5% by mass, the laser etching processability may be deteriorated.

  In the present specification, the particle diameter and the average particle diameter D50 indicate values measured by a laser diffraction type microtrack particle diameter distribution measuring apparatus. Examples of the measuring apparatus include Microtrack particle size distribution measuring apparatus MT3000II series (laser diffraction / scattering method) manufactured by Microtrack Bell Co., Ltd.

Examples of the copper particles used in the present invention include known copper particles generally used for copper paste and copper ink. The shape may be any of a spherical shape, a plate shape, a dendritic shape, a rod shape, and a fibrous shape, and may be an indefinite shape such as a hollow shape or a porous shape. Furthermore, a core-shell shape in which the shell is copper and the core is a material other than copper may be used. In particular, in the case of a copper paste composition for laser etching produced using plate-like particles, when a copper cured film is formed to form a wiring on a substrate, the copper paste composition originates from the particle shape. It is particularly preferable to use plate-like particles because the shrinkage in curing in the substrate plane direction is suppressed, so that deformation is suppressed and adhesion to the substrate is excellent. In this specification, the definition of the plate-like particle is that the value of the ratio “D50 / average thickness” between the average particle diameter D50 of the copper particles and the average thickness of the particles is 1.5 to 20. In the present specification, the thickness of the particle means a length in a direction perpendicular to the planar spread of the plate-like particle. In addition, the average thickness of the particles is the measured value of the thickness of the particles calculated by image analysis by selecting arbitrary 100 particles in the observation result image of the particles obtained by scanning electron micrograph (SEM) observation. Average value.
Moreover, although the copper particle used for (A) may be one kind, you may mix and use the copper particle of a different shape.

(A) is a first coating layer of an amine compound represented by formula (1) that is bonded to copper on the surface of the copper particles by chemical bonding or physical bonding, and the amine compound is formed on the first coating layer. And a second coating layer of an aliphatic monocarboxylic acid having 8 to 20 carbon atoms bonded by a chemical bond.
[In the formula (1), m is an integer of 0 to 3, n is an integer of 0 to 2, and when n = 0, m is any of 0 to 3, when n = 1 or n = 2, m is any one of 1-3. ]

The first coating layer (A) is a layer of an amine compound that is chemically and / or physically bonded and adsorbed to copper on the surface of the copper particles. From the viewpoint of oxidation resistance, it is ideal that the amine compound is uniformly coated on the copper particle surface in the form of a monomolecular film. However, in practice, it is difficult to achieve such an ideal state. There may be a portion where the amine compound is not adsorbed on the copper surface, or there may be a portion where two or more molecules are laminated and adsorbed.
Therefore, the first coating layer in the present invention includes not only a layer in which the amine compound uniformly coats the copper surface but also a coating layer in which a copper surface on which the amine compound is not adsorbed partially exists.
In addition, it shall confirm by IR measurement of the copper surface mentioned later that the amine compound adsorb | sucks on the copper surface, and forms the 1st coating layer.

Here, the adsorption by the chemical bond indicates that the amine compound forms a bond by electrostatic interaction with the copper surface and is adsorbed on the copper surface. The electrostatic interaction as used herein refers to hydrogen bonding, interaction between ions (ionic bonding), and the like. Moreover, adsorption | suction by a physical coupling | bonding refers to adsorb | sucking to the copper surface by the physical adsorption | suction by van der Waals force. In particular, the amino group has a high electron donating property, and it is considered that the amino group forms a bond by forming a coordination to copper. Therefore, the amine compound mainly forms a bond on the copper surface by a chemical bond by electrostatic interaction. It is considered that the first coating layer is formed by adsorption. However, there may be some adsorption due to physical bonding.
Further, there may be a portion in which two or more molecules of amine compounds are bonded by, for example, hydrogen bonding.

The second coating layer (A) is a layer laminated on the first coating layer, and is an aliphatic monocarboxylic acid having 8 to 20 carbon atoms that is bonded to the amine compound of the first coating layer by a chemical bond. Layer.
Here, the chemical bond means that the carboxyl group of the aliphatic monocarboxylic acid and the amino group of the amine compound are bonded by electrostatic interaction. The electrostatic interaction as used herein refers to hydrogen bonding, interaction between ions (ionic bonding), and the like. That is, the second coating layer is a layer of an aliphatic monocarboxylic acid bonded to the amine compound of the first coating layer by electrostatic interaction. Ideally, it is preferable that the amine compound of the first coating layer and the aliphatic monocarboxylic acid react with each other at a ratio of 1: 1 to form the second coating layer. It is difficult to become. Accordingly, there may be an amine compound in the first coating layer that is not partially bonded to the aliphatic monocarboxylic acid, and in the second coating layer, two or more molecules of the aliphatic monocarboxylic acid are laminated by physical adsorption or the like. There may be a portion that is adsorbed.
Therefore, the second coating layer in the present invention is not only a layer in which the aliphatic monocarboxylic acid uniformly covers the first coating layer, but also the aliphatic monocarboxylic acid is an amine compound, as in the first coating layer. It also includes a coating layer formed so that a part that is not bonded is partially present.
In addition, it shall confirm by IR measurement of the copper surface mentioned later that the aliphatic monocarboxylic acid adsorb | sucks and forms the 2nd coating layer similarly to the 1st coating layer.

  Furthermore, when there is a part of the copper surface to which the amine compound is not bonded, there may be a portion where the aliphatic monocarboxylic acid is directly adsorbed on the copper surface, and such surface-coated copper particles are also present. It is (A) within the scope of the invention.

  The amine compound that forms the first coating layer is an amine compound represented by the above formula (1). Specifically, hydrazine, methylenediamine, ethylenediamine, 1,3-propanediamine, dimethylenetriamine, trimethylenetetraamine, tetramethylenepentamine, diethylenetriamine, triethylenetetraamine, tetraethylenepentamine, dipropylenetriamine, triethylene Examples include propylene tetraamine and tetrapropylene pentaamine. A 1st coating layer may be formed with one type of amine compound among these, and may be formed using a plurality of types.

  When the value of m in the formula (1) is 4 or more, the number of amino groups per unit area on the copper particle surface of amino groups contributing to chemical bonding and reducing properties decreases, so that the desired oxidation resistance May become insufficient, and copper surface oxidation may easily proceed. Further, when n in the formula (1) is 3 or more, the molecular chain becomes too long, resulting in steric hindrance with the adjacent amine compound during coating, and the copper particle surface cannot be sufficiently coated. Therefore, there is a possibility that the surface oxidation of copper is likely to proceed.

The aliphatic monocarboxylic acid having 8 to 20 carbon atoms forming the second coating layer used in the present invention is a linear saturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms or linear unsaturated group having 8 to 20 carbon atoms. Examples thereof include aliphatic monocarboxylic acids, branched saturated aliphatic monocarboxylic acids having 8 to 20 carbon atoms, and branched unsaturated aliphatic monocarboxylic acids having 8 to 20 carbon atoms. Specific examples of the linear saturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include caprylic acid, pelargonic acid, capric acid, undecylic acid, lauric acid, tridecanoic acid, myristic acid, pentadecanoic acid, palmitic acid, and margarine. Examples include acid, stearic acid, nonadecanoic acid, and arachidic acid. Examples of the linear unsaturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include myristoleic acid, palmitoleic acid, petroceric acid, and oleic acid. Examples of the branched saturated aliphatic monocarboxylic acid having 8 to 20 carbon atoms include 2-ethylhexanoic acid. The said aliphatic monocarboxylic acid may be used by 1 type, and may mix and use several types.
If the carbon number is 7 or less, the dispersibility of the surface-coated copper particles may be low because the alkyl chain length is short. When the carbon number is 21 or more, the hydrophobicity of the aliphatic monocarboxylic acid is increased, so that the compatibility with the binder is increased. When the copper paste composition for laser etching is used, the aliphatic monocarboxylic acid is converted from the second coating layer. Is easily detached and eluted to the binder side.

  In order to further improve the dispersibility in the copper paste composition for laser etching of (A) and reduce the amount of free aliphatic monocarboxylic acid in the copper paste composition, the number of carbon atoms is 10-18. Of these, aliphatic monocarboxylic acids are preferred. Furthermore, linear saturated aliphatic monocarboxylic acids have a finer packing structure than aliphatic monocarboxylic acids having branched chains and unsaturation, and are covered with fewer voids, so that they are linear saturated fatty acids having 10 to 18 carbon atoms. More preferably, an aromatic monocarboxylic acid is used for coating.

(A) shows that two coating layers of a first coating layer of an amine compound represented by the formula (1) and a second coating layer of an aliphatic monocarboxylic acid having 8 to 20 carbon atoms are on the surface of the copper particles. It is characteristic that it is formed.
The amine compound has an effect of removing an oxide on the metal surface and an effect of suppressing oxidation because the amino group has reducibility.
In addition, the amine compound has a higher coordination ability to the metal than the aliphatic monocarboxylic acid due to the effect of the lone pair of nitrogen of the amino group and binds to the copper surface with a stronger bond than the aliphatic monocarboxylic acid. It is considered that the surface coverage is higher than that of carboxylic acid. Moreover, an amine compound tends to form a bond by an electrostatic interaction with an aliphatic monocarboxylic acid. Here, the electrostatic interaction refers to a hydrogen bond and an ion-ion interaction. Therefore, after coating the copper surface with an amine compound having a high surface coverage, the outer surface is further coated with an aliphatic monocarboxylic acid, so that the aliphatic monocarboxylic acid is coated on the copper particles directly rather than directly. The aliphatic monocarboxylic acid can be coated on the copper particles at a high rate. Therefore, the surface-coated copper particles of the present invention have higher oxidation resistance than copper particles coated only with aliphatic monocarboxylic acid due to the oxidation-inhibiting effect of the amine compound and the high coverage of aliphatic monocarboxylic acid. Yes.

  Furthermore, as described above, the aliphatic monocarboxylic acid is considered to have its carboxyl group bonded to the amino group of the amine compound by electrostatic interaction. That is, it is considered that the second coating layer is formed with the carboxyl group of the hydrophilic group facing the first coating layer side of the amine compound and the alkyl group of the hydrophobic group facing the outside. Therefore, (A) of the present invention having the second coating layer of the aliphatic monocarboxylic acid can suppress the aggregation of the copper particles and also suppress the detachment of the amine compound, as compared with the copper particles coated only with the amine compound. be able to.

It can be confirmed that (A) is coated with an amine compound and an aliphatic monocarboxylic acid by measuring an infrared absorption (IR) spectrum of the surface-coated copper particles.
As an example, FIG. 1 shows an IR spectrum of surface-coated copper particles coated with ethylenediamine and myristic acid (Example 1 described later).
When the amine compound used for coating is measured alone, the peak of N—H bending vibration appears at 1598 cm ⁻¹ (FIG. 2), whereas the N—H change observed in the surface-coated copper particles. The peak of angular vibration is shifted to the low wavenumber side of 1576 cm ⁻¹ , indicating that the amine compound is present on the copper particle surface. Further, in FIG. 1, the peak of C═O stretching vibration of the aliphatic monocarboxylic acid is not observed at 1700 cm ^−1, and the peak of the carboxylic acid anion (—COO ⁻ ) is observed near 1400 cm ^−1. It shows that the acid is present by binding with the amine compound by electrostatic interaction.

[Binder (B); hereinafter may be simply referred to as (B)]
10-30 mass parts is preferable with respect to 100 mass parts of (A), and, as for content of (B) in the copper paste composition for laser etching, 15-25 mass parts is more preferable. If content of (B) is 10 mass parts or more, the adhesiveness of copper particles when it is set as a copper cured film and fine copper wiring will be favorable, and laser etching processability will be favorable. Moreover, if it is 30 mass parts or less, the copper cured film and fine copper wiring of a low volume resistivity will be easy to be obtained.
(B) may be any known binder used for metal pastes, and examples include resins such as thermosetting resins, photocurable resins, and thermoplastic resins that cure by applying heat or light. Can do.

  Examples of thermosetting resins include epoxy resins, melamine resins, phenol resins, silicone resins, oxazine resins, urea resins, polyurethane resins, unsaturated polyester resins, vinyl ester resins, xylene resins, acrylic resins, oxetane resins, diallyl phthalate resins, Examples thereof include an oligoester acrylate resin, a bismaleide triazine resin, and a furan resin. Examples of the photocurable resin include silicon resin, acrylic resin, imide resin, and urethane resin.

  Examples of the thermoplastic resin include polyvinyl chloride, polyethylene, polypropylene, polystyrene, acrylonitrile-butadiene-styrene copolymer resin, acrylonitrile-styrene copolymer resin, polymethylmethacrylate, polyvinyl alcohol, polyvinylidene chloride, polyethylene terephthalate, polyamide, Polyacetal, polycarbonate, polyphenylene ether, polybutylene terephthalate, polyvinylidene fluoride, polysulfone resin, polyether sulfone resin, polyphenylene sulfide resin, polyarylate, apolyamideimide, polyetherimide, polyetheretherketone, polyamide, polyimide, liquid crystal polymer And polytetrafluoroethylene.

  As (B), any one of these may be used, or two or more may be mixed and used.

[Antioxidant (C); hereinafter may be simply referred to as (C)]
The content of (C) in the copper paste composition for laser etching is preferably 0.1 to 7.0 parts by mass, more preferably 0.3 to 3.0 parts by mass with respect to 100 parts by mass of (A). . If content of (C) is 0.1 mass part or more, favorable antioxidant performance will be exhibited and it will become easy to obtain a highly conductive copper cured film and copper wiring. On the other hand, if it exceeds 7.0 parts by mass, the storage stability of the copper paste composition for laser etching may be lowered.
(C) is not particularly limited as long as it has functions such as oxidation prevention, reduction, oxide film removal by chelation, radical trapping, etc. on copper of (A). For example, hydrazides, cyclic borane complexes, phosphites, sulfur compounds, polyamines, oximes, nitrogen-containing intermetallic compounds, carotenoids, phenols, ascorbic acid derivatives, Schiff bases, hydroquinone, Examples thereof include dibutylhydroxytoluene and butylhydroxyanisole.

  Examples of hydrazides include formic hydrazide, maleic hydrazide, 4-methylbenzenesulfonic acid hydrazide, salicyl hydrazide, adipic acid dihydrazide, dodecanedioic acid dihydrazide, dodecanedioic acid bis (2- (2-salicyloyl) hydrazide), N′- Examples thereof include isopropylidene-2-nitrobenzenesulfonohydrazide, 1,2-bis (3,5-di-tert-butyl-4-hydroxyhydrocinnamoyl) hydrazine and the like.

  Examples of the cyclic borane complexes include borane-morpholine complex, borane-4-methylmorpholine complex, borane-4-ethylmorpholine complex, borane-pyridine complex, borane-N, N-dimethylaniline complex, borane-1,4-oxathiane. A complex, a borane-piperidine complex, and the like.

  Phosphites include triphenyl phosphite, trisnonylphenyl phosphite, tricresyl phosphite, triethyl phosphite, tris (2-ethylhexyl) phosphite, tridecyl phosphite, trilauryl phosphite, tris ( Tridecyl) phosphite, trioleyl phosphite, diphenyl mono (2-ethylhexyl) phosphite, diphenyl monodecyl phosphite, diphenyl mono (tridecyl) phosphite, trilauryl trithiophosphite, tetraphenyldipropylene glycol diphosphite, tetra Phenyl (tetratridecyl) pentaerythritol tetraphosphite, bis (decyl) pentaerythritol diphosphite, bis (tridecyl) pentaerythritol diphosphite Sufaito, tristearyl phosphite, distearyl pentaerythritol diphosphite, tris (2,4-di -tert- butylphenyl) phosphite.

  Examples of sulfur compounds include dilauryl-3,3′-thiodipropionate, ditridecyl-3,3′-thiodipropionate, dimyristyl-3,3′-thiodipropionate, distearyl-3,3 ′. -Thiodipropionate, tetrakis-methylene-3-laurylthiopropionate methane, distearyl-3,3'-methyl-3,3'-thiodipropionate, laurylstearyl-3,3'-thiodipropioate And bis [2-methyl-4- (3-n-alkylthiopropionyloxy) -5-tert-butylphenyl] sulfide, β-laurylthiopropionate, thiocyanuric acid and the like.

  Examples of polyamines include trimethylenetetraamine, tetramethylenepentamine, triethylenetetraamine, tetraethylenepentamine, tripropylenetetraamine, tetrapropylenepentamine, 1,2-phenylenediamine, 1,3-phenylenediamine, , 4-phenylenediamine, 2,5-dimethyl-1,4-phenylenediamine, 2,3,5,6-tetramethyl-1,4-phenylenediamine, N, N-dimethyl-1,4-phenylenediamine, N , N, N′N′-tetramethyl-1,4-phenylenediamine, N, N′-diphenyl-1,4-phenylenediamine, and the like.

  Examples of oximes include salicylaldoxime, acetone oxime, isobutyl methyl ketoxime, dimethylglyoxime, cyclohexanone oxime, methyl ethyl ketoxime, acetoxime, and acetaldehyde oxime.

  Nitrogen-containing intermetallic compounds include 2,2-bipyridyl, 1,10-phenanthroline and the like.

  As (C), any one of these may be used, or two or more kinds may be mixed and used. Salicylhydrazide, adipic acid dihydrazide, dodecanedioic acid dihydrazide, dodecanedioic acid bis (2- (2-salicyloyl) hydrazide), tridecyl phosphite, 1,4-phenylenediamine, 2,2-bipyridyl, and 1,10- From the viewpoint of conductivity, it is preferable to use one or more types selected from phenanthroline.

[Solvent (D); hereinafter may be simply referred to as (D)]
1-30 mass parts is preferable with respect to 100 mass parts of (A), and, as for content of (D) in the copper paste composition for laser etching, 1-20 mass parts is more preferable.
In the copper paste composition for laser etching of the present invention, when light or heat is applied, shrinkage occurs due to volatilization of the solvent or curing of the binder, and the copper particles approach each other due to the shrinkage and express conductivity. Therefore, the amount of solvent is preferably as small as possible in order to develop conductivity, but the above range is preferable in terms of viscosity suitable for application to a substrate.
(D) is not particularly limited as long as it dissolves (B), and examples thereof include ether alcohols, non-ether alcohols, esters, ketones, terpenes, and other hydrocarbons. It is done.

  Examples of ether alcohols include diethyl ether, ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol mono-n-propyl ether, ethylene glycol mono-isopropyl ether, ethylene glycol mono-n-butyl ether, ethylene glycol dimethyl ether, ethylene Glycol methyl ethyl ether, ethylene glycol ethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol diethyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene glycol monomethyl ether acetate, ethylene glycol monomethyl ether, diethylene glycol monoethyl ether Tate, propylene glycol monoethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether, and propylene glycol monomethyl ether, and the like.

  Examples of the non-ether alcohols include methyl alcohol, ethyl alcohol, isopropyl alcohol, cyclohexanol, ethylene glycol, propylene glycol, 1,4-butanediol, and triethylene glycol.

  Examples of the esters include ethyl lactate, butyl lactate, methyl acetate, ethyl acetate, butyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, diethyl oxalate, and diethyl malonate.

  Examples of ketones include acetone, methyl ethyl ketone, methyl isobutyl ketone, and cyclohexanone.

  Examples of terpenes include terpine oil, terpineol, borneol, and α-pinene.

  Other hydrocarbons Examples include tetrahydrofuran, dichloromethane, 1,2-dichloroethane, 1,4-dichlorobutane, trichloroethane, chlorobenzene, o-dichlorobenzene, hexane, heptane, octane, diacetone alcohol, and propylene carbonate.

  As (D), any one of these may be used, or two or more kinds may be mixed and used. In particular, it is preferable to use one or more selected from ether alcohols, esters or terpenes.

  In addition to (A) to (D), the laser etching copper paste composition of the present invention contains various known additives such as a leveling agent, a viscosity modifier, a dispersant, a curing agent, and a foaming agent, as necessary. It can contain suitably.

<Method for producing surface-coated copper particles (A)>
Next, the manufacturing method (A) of the present invention will be described.
(A) can be produced by a method having the following steps 1 to 5. Preferably, a pretreatment step described below is performed before step 1. Since the copper particles may have impurities such as copper salts, dispersants, and copper oxides derived from their production attached to the surface, it is preferable to remove these impurities before step 1. This is because the dispersibility of the copper particles in a highly polar solvent such as water can be improved, and the coverage of the amine compound and the aliphatic monocarboxylic acid on the surface of the copper particles can be improved.

[Pretreatment process]
The method is not particularly limited as long as the impurities can be removed from the surface of the copper particles. For example, there is a cleaning method using an organic solvent or an acid. There are no particular restrictions on the type of organic solvent, but those having good wettability to the surface of the copper particles and easy to remove after the washing treatment may be used alone or in combination. Specific examples include alcohols, ketones, hydrocarbons, ethers, nitriles, isobutyronitriles, water, and 1-methyl-2-pyrrolidone. As the acid, an organic acid or an inorganic acid can be preferably used. Examples of the organic acid include acetic acid, glycine, alanine, citric acid, malic acid, maleic acid, malonic acid and the like. Examples of the inorganic acid include hydrochloric acid, nitric acid, sulfuric acid, hydrogen bromide, phosphoric acid and the like. As a density | concentration of an acid, 0.1-50 mass% is preferable, and in order to suppress the heat of reaction, 0.1-10 mass% is more preferable. If it is less than 0.1% by mass, the removal of impurities may be insufficient, and if it exceeds 50% by mass, there is no difference in effect, and the impurity removal cost may increase.
In addition, when the washing process by an acid is implemented, in order to prevent the residue of the acid to the copper particle surface, it is preferable to wash | clean further with water or an organic solvent after acid washing.

[Step 1]
Step 1 is a step of coating the surface of the copper particles with the amine compound represented by the formula (1).
[In the formula (1), m is an integer of 0 to 3, n is an integer of 0 to 2, and when n = 0, m is any of 0 to 3, when n = 1 or n = 2, m is any one of 1-3. ]
Specifically, the copper particle surface is obtained by adding pretreated copper particles or non-pretreated copper particles to a mixture a in an amine compound solution containing an amine compound, and stirring the mixture a. To form a first coating layer of the amine compound. The stirring method is not particularly limited, and stirring may be performed so that the copper particles and the amine compound are in sufficient contact, and a general stirring method may be used using a known stirrer such as a paddle stirrer or a line mixer.

Ideally, it is desirable to form a first coating layer in which the surface of the copper particles is uniformly coated with a monomolecular film of an amine compound, and it is preferable to form a good first coating layer as close to ideal as possible. . Therefore, the mixing ratio of the copper particles and the amine compound in step 1 is preferably a ratio suitable for forming this good first coating layer.
Specifically, although depending on the particle diameter of the copper particles, 0.1 to 200 parts by mass is preferable with respect to 100 parts by mass of the copper particles. 1-100 mass parts is more preferable at the point which suppresses that a free amine compound remains in surface-coated copper particles. Since the surface area per unit mass increases as the particle diameter of the copper particles decreases, it is preferable to increase the mixing amount of the amine compound as the particle diameter decreases.

  The solvent for preparing the amine compound solution is not particularly limited as long as the amine compound dissolves, has good wettability with the copper particles, and does not react with the amine compound and the aliphatic monocarboxylic acid. Preferably, it is a solvent containing at least one selected from alcohols, ketones, ethers, nitriles, sulfoxides, pyrrolidones, and water. Specifically, alcohols include methanol, ethanol, 1-propanol, isopropyl alcohol, 1-butanol, 2-butanol, 1-pentanol, tert-amyl alcohol, ethylene glycol, butoxyethanol, methoxyethanol, ethoxyethanol, Examples include propylene glycol, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether and dipropylene glycol monomethyl ether. Examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of ethers include diethyl ether and dibutyl ether. Nitriles include acetonitrile, propionitrile, butyronitrile and isobutyronitrile. Examples of the sulfoxides include dimethyl sulfoxide. Examples of pyrrolidones include 1-methyl-2-pyrrolidone.

The treatment temperature for forming the first coating layer may be at or above the temperature at which the coating of the amine compound proceeds and the solution does not solidify, and is preferably a temperature at which the promotion of copper oxidation is low. Specifically, it is preferably performed in the range of −10 to 120 ° C. It is more preferable to carry out in the range of 30 to 100 ° C. in that the coating speed can be further increased and oxidation promotion can be further suppressed.
The treatment time is not particularly limited, but is preferably 5 minutes to 10 hours. Moreover, 5 minutes-3 hours are more preferable at the point of manufacturing cost. If it is less than 5 minutes, the coating with the amine compound may be insufficient. If it exceeds 10 hours, the amine compound forms a salt with carbon dioxide mixed in from the atmosphere, and the surface-coated copper particles May remain as an impurity.

  In addition, the step 1 is preferably performed in an inert gas atmosphere in that it is possible to suppress salt formation between an amine compound and carbon dioxide in the atmosphere and oxidation of copper. For example, bubbling of an inert gas or the like is performed. Preferably it is done. Specific examples of the inert gas include nitrogen, argon, helium and the like. The bubbling may also be used for stirring, that is, if the copper particles and the amine compound can be sufficiently contacted only by bubbling with an inert gas, stirring is not particularly required.

[Step 2]
Step 2 is a step in which an amine compound solution containing a free amine compound that has not been used for forming the first coating layer is removed from the mixture a to obtain an intermediate 1 containing the first coating layer-forming copper particles. . That is, it is a step of removing excess amine compound solution. At this time, it is not necessary to completely remove the excess amine compound, and the intermediate 1 can be obtained by natural sedimentation, separation by centrifugation, or filtration. That is, the intermediate 1 contains a small amount of a free amine compound and a solvent, but may proceed to the next step 3 as it is. In view of simple operation, a method of removing the supernatant amine compound solution by decantation or suction by an aspirator after the copper particles having the first coating layer formed by sedimentation by natural sedimentation is preferable.
In addition, the separated precipitate or filtrate may be washed with a solvent capable of dissolving both the amine compound and the aliphatic monocarboxylic acid having 8 to 20 carbon atoms to obtain the intermediate 1. This washing is preferable because the amount of free amine compound can be reduced. However, washing with water is not preferable because the amine compound forming the first coating layer may be detached.
The intermediate 1 may be dried to reduce the content solvent (the solvent of the amine compound solution), but drying at this stage may oxidize the copper surface, so drying, particularly heat drying, is performed. It is preferable not to.

If a large amount of free amine compound remains in the intermediate 1, impurities generated when the amine compound forms a salt with carbon dioxide or aliphatic monocarboxylic acid in the atmosphere may cause the conductivity of the copper paste composition for laser etching. Unfavorable because it adversely affects.
Therefore, the amount of the amine compound in the intermediate 1 is preferably 10% by mass or less of the amount of copper particles as the total amount of the amine compound and the free amine compound forming the first coating layer. In view of not affecting the formation of the second coating layer of the aliphatic monocarboxylic acid, the content is more preferably 1.0% by mass or less. The amount of amine compound in intermediate 1 can be determined from the difference from the amount of amine compound used in step 1 by measuring the amount of amine compound such as supernatant.

[Step 3]
Step 3 is a step of forming a second coating layer of an aliphatic monocarboxylic acid having 8 to 20 carbon atoms on the first coating layer.
Specifically, an aliphatic monocarboxylic acid solution containing an aliphatic monocarboxylic acid having 8 to 20 carbon atoms is added to the intermediate 1 to obtain a mixture b, and the mixture b is agitated, whereby the first coating layer is formed. To form a second coating layer of an aliphatic monocarboxylic acid. The intermediate 1 may be added to an aliphatic monocarboxylic acid solution containing an aliphatic monocarboxylic acid having 8 to 20 carbon atoms to form a mixture b. The stirring method is not particularly limited, and the stirring may be performed so that the copper particles on which the first coating layer is formed and the aliphatic monocarboxylic acid are in sufficient contact with each other, using a known stirrer such as a paddle stirrer or a line mixer. A general stirring method may be used.

Ideally, a second coating layer in which the first coating layer is uniformly coated with an aliphatic monocarboxylic acid in the form of a monomolecular film is formed by the bond between the amine compound of the first coating layer and the aliphatic monocarboxylic acid. It is desirable that a good second coating layer as close to ideal as possible be formed. Accordingly, the mixing ratio of the copper particles and the aliphatic monocarboxylic acid in step 3 is preferably a ratio suitable for forming this good second coating layer.
Specifically, although depending on the particle diameter of the copper particles, 0.1 to 50 parts by mass is preferable with respect to 100 parts by mass of the copper particles. 0.5-10 mass parts is more preferable at the point which suppresses that a free aliphatic monocarboxylic acid remains in surface-coated copper particles. Since the surface area per unit mass increases as the particle size of the copper particles decreases, it is preferable to increase the amount of the aliphatic monocarboxylic acid mixed as the particle size decreases.

The solvent for preparing the aliphatic monocarboxylic acid solution having 8 to 20 carbon atoms is good in wettability with the copper particles in which the aliphatic monocarboxylic acid is dissolved and the copper particles and the first coating layer are formed. And it will not be specifically limited if it does not react with aliphatic monocarboxylic acid. Any solvent that can be easily removed by drying in the drying step of Step 5 described later is preferable.
A preferable solvent is a solvent containing at least one selected from alcohols, ketones, ethers, nitriles, sulfoxides, and pyrrolidones. Specifically, alcohols are methanol, ethanol, 1-propanol, 2-propanol, 1-butanol, 2-butanol, 1-pentanol, tert-amyl alcohol, ethylene glycol, butoxyethanol, methoxyethanol, ethoxyethanol. , Propylene glycol, propylene glycol monomethyl ether, propylene glycol monopropyl ether, propylene glycol monobutyl ether and dipropylene glycol monomethyl ether. Examples of ketones include acetone, methyl ethyl ketone, and methyl isobutyl ketone. Examples of ethers include diethyl ether and dibutyl ether. Nitriles include acetonitrile, propionitrile, butyronitrile and isobutyronitrile. Examples of the sulfoxides include dimethyl sulfoxide. Examples of pyrrolidones include 1-methyl-2-pyrrolidone.

The treatment temperature for forming the second coating layer may be at or above the temperature at which the coating of the aliphatic monocarboxylic acid proceeds and the solution does not solidify. Specifically, the treatment temperature is in the range of −10 to 80 ° C. Is preferred. It is more preferable to carry out in the range of 10 to 60 ° C. in terms of further increasing the coating speed and suppressing the elimination of the aliphatic monocarboxylic acid that has formed the second coating layer.
The treatment time is not particularly limited, but is preferably 5 minutes to 10 hours. Moreover, 5 minutes-3 hours are more preferable at the point of manufacturing cost. If it is less than 5 minutes, the coating with the aliphatic monocarboxylic acid may be insufficient, and if it exceeds 10 hours, the component released as a copper-amine compound-fatty acid complex remains in the surface-coated copper particles. This is not preferable because it may adversely affect the conductivity of the copper paste composition for laser etching.

  In addition, the step 3 is also an inert gas atmosphere in that the salt formation between the amine compound of the first coating layer and the free amine compound mixed in a small amount and carbon dioxide in the atmosphere can be suppressed and copper oxidation can be suppressed. For example, it is preferable to perform bubbling of an inert gas. Specific examples of the inert gas include nitrogen, argon, helium and the like. Further, the bubbling may also be used for stirring, that is, if the copper particles on which the first coating layer is formed and the aliphatic monocarboxylic acid can be sufficiently contacted only by bubbling with an inert gas, In particular, stirring may not be performed.

[Step 4]
Step 4 removes the aliphatic monocarboxylic acid solution containing the free aliphatic monocarboxylic acid that was not used to form the second coating layer from the mixture b, and contains the first and second coating layer-forming copper particles. It is the process of obtaining the intermediate body 2 to do. Specifically, the intermediate 2 can be obtained by filtration. As a filtration method, a known method can be applied, and natural filtration, vacuum filtration, pressure filtration, and the like can be exemplified. In addition, in order to remove free aliphatic monocarboxylic acid and free amine compound as much as possible, the filtrate is washed with a solvent that can dissolve both the aliphatic monocarboxylic acid having 8 to 20 carbon atoms and the amine compound. Thus, the intermediate 2 is preferable. By reducing the amount of free aliphatic monocarboxylic acid by washing, the adhesiveness of the composition to the substrate is improved when a copper paste composition for laser etching is obtained.

[Step 5]
Step 5 is a step of drying the intermediate 2 to obtain the surface-coated copper particles (A) of the present invention.
The drying method is not particularly limited, and examples thereof include reduced-pressure drying and freeze-drying. Vacuum drying is preferable from the viewpoint of production cost, and the drying temperature is preferably 20 to 120 ° C. If it is less than 20 ° C., the drying time may be long, and if it is higher than 120 ° C., copper may be oxidized. The degree of vacuum, the drying temperature, and the drying time may be appropriately determined depending on the combination of the respective conditions and the type of the solvent used, and so on until the amount of the solvent in the surface-coated copper particles after drying becomes 1% by mass or less. Any conditions that can be dried are preferred.
The surface-coated copper particles (A) can be produced by the above production method.

<Method for producing copper paste composition for laser etching>
The copper paste composition for laser etching of the present invention can be produced by mixing (A) to (D) and optionally other additives using a kneading (mixing) device. As the kneading apparatus, a three-roll kneader can be used. The kneading temperature is in the range of 10 to 60 ° C., and the number of kneading may be any condition as long as the particles can be uniformly dispersed in the paste. The order of addition (mixing) of (A) to (D) may be any order, and may be added together and kneaded and mixed.
Hereinafter, the copper paste composition for laser etching may be simply referred to as a copper paste composition.

<Method of forming a cured copper film>
A copper paste film can be formed by applying the copper paste composition onto a substrate by screen printing and heating at 100 ° C. to 200 ° C. for 10 to 120 minutes. Heating can be performed using a drying oven, a hot plate, an IR baking apparatus, a light baking apparatus, or the like. As the cured film, the binder (B) is heated under the conditions that the crosslinking (B) is sufficiently cured by heat and thermally cured, and the solvent (D) is removed by drying.

<Method of forming fine copper wiring by laser etching>
[Laser etching]
Laser etching refers to cutting the surface by irradiating a workpiece with laser light from each medium. In the conductive wiring, at the site where the laser beam is irradiated and absorbed, the energy of the applied laser beam is converted into heat, and the irradiated site is peeled off and removed. In the copper paste composition of the present invention and the formed conductive wiring, it is preferable that the portion irradiated with the laser light is efficiently removed from the base material so as to have strong absorption at the wavelength of the irradiation laser light. Therefore, it is preferable to select a laser species having energy in a wavelength region where any component constituting the conductive thin film has strong absorption.
Commonly known processing lasers include CO ₂ lasers, YAG lasers, excimer lasers, fiber lasers, and the like, but lasers of any system, wavelength, and intensity may be used. Of the wiring formed from the copper paste composition, a laser that matches the absorption wavelength of the resin or copper particles and has little damage to the substrate such as PET is particularly suitable. From such a viewpoint, the wavelength of the fundamental wave is preferably in the range of 532 to 10700 nm as the laser type to be irradiated. For example, when using as a substrate a PET film, a transparent conductive laminate in which an ITO layer is formed on a PET film, or a laminate in which an ITO layer is formed on a PET film and part thereof is removed by etching Processing with a fiber laser is more preferable because the base material has no absorption at the wavelength of the fundamental wave and is difficult to damage the base material.
As an apparatus for laser etching, RICOH LA-1100 [manufactured by Ricoh Industrial Solutions Co., Ltd.] can be exemplified.

[Method of forming fine copper wiring]
The cured copper film formed as described above is processed into fine copper wiring by laser etching by the laser light irradiation.
Processing conditions such as laser output, number of processing, scanning speed are not particularly limited, but the copper cured film of the laser light irradiation part can be removed, the copper particles of the copper wiring part are not oxidized, and remain conductive after processing, In addition, the substrate is adjusted so that the underlying substrate is not damaged.
Laser oscillation modes include continuous oscillation, pulse oscillation, etc., but are not particularly limited, and those in which the copper cured film in the irradiated part can be easily removed without damaging the substrate and the wiring in the non-irradiated part. It is preferable to select. In the case of continuous oscillation, the output value is continuously oscillated and irradiated, so it is easy to obtain high output, and it is often used for welding and cutting, but damage to the base material in the irradiated area and copper particles in the unirradiated area Easy to receive. Pulse oscillation oscillates the output value in a pulse shape, enabling processing with reduced thermal effects and adjusting the processing conditions with the repetition frequency and pulse width, avoiding thermal effects such as micromachining. Suitable for processing. Therefore, the pulse mode is more preferable.
The pulse width of the laser is not particularly limited, but with a long pulse laser, energy is accumulated in the irradiated part for a long time, and heat is also transferred to the non-irradiated part in the wiring, causing damage. Conditions are limited. A short pulse laser has a narrow range of damage and is suitable for fine processing. Therefore, it is preferable to process with a pulse width as short as possible.
Although it does not specifically limit about a laser output, It adjusts so that the copper cured film of an irradiation part can be removed and a base material is not damaged. In general, the laser output is preferably adjusted as appropriate in the range of 0.5 to 100 W. If the laser power is too low, removal of the copper wiring may be insufficient. If the laser output is too high, the irradiated portion becomes larger than the laser diameter due to the diffusion of heat from the irradiated portion, and the line width may become too thin or may be disconnected.
The number of times the laser beam is scanned is not particularly limited as long as the copper cured film in the irradiated portion can be removed and the base material is not damaged. As the same pattern is repeated a plurality of times, the cured copper film on the irradiated part can be removed more reliably, but thermal damage may be accumulated in the non-irradiated part.
The laser beam scanning speed is preferably as high as possible from the viewpoint of improving the production efficiency due to the reduction of the tact time. When the scanning speed is too low, not only the production efficiency is lowered, but energy is excessively applied to the copper cured film and the base material, and there is a possibility that the portion to be the copper wiring and the base material are damaged. The upper limit of the processing speed is not particularly limited. However, if the scanning speed is too high, the removal of the cured copper film in the irradiated portion may be incomplete and the circuit may be short-circuited, so that it is preferably 5000 mm / s or less.

Hereinafter, the embodiments of the present invention will be described more specifically with reference to Examples and Comparative Examples, but the present invention is not limited thereto.
The raw material copper particles used in each example and comparative example, and the measurement method, processing method, and evaluation method are shown below.

<Raw material copper particles>
Copper particles 1, 2, 3; 1100YP (Mitsui Metals Mining Co., Ltd.). Copper particles 1, 2, and 3 are due to differences in production lots.
Copper particles 4; 1400 YP (Mitsui Metals Mining Co., Ltd.)
Copper particle 5; 1200 YP (Mitsui Metals Mining Co., Ltd.)
Table 1 shows the average particle diameter D50, the content of the particle diameter of 3 μm or more, the average thickness of the particles, and the value of D50 / average thickness of each copper particle.

<Pretreatment of copper particles>
Each raw material copper particle was subjected to the same pretreatment by the following method.
220 g of copper particles were put into a mixed solution of 352 g of toluene and 88 g of isopropanol, and refluxed at 70 ° C. for 30 minutes while being stirred and dispersed. After refluxing, toluene and isopropanol were removed from the copper particle-containing mixture by vacuum filtration. The filtered copper particles were put into 440 g of 3.5% hydrochloric acid aqueous solution and stirred at 30 ° C. for 30 minutes. After stirring, the aqueous hydrochloric acid solution was removed from the aqueous hydrochloric acid solution containing copper particles by filtration under reduced pressure. Subsequently, the filtered copper particles were put into 440 g of isopropanol and stirred at 30 ° C. for 15 minutes. After stirring, isopropanol was removed from the copper particle-containing isopropanol by filtration under reduced pressure, and the filtered copper particles were dried under reduced pressure at 25 ° C. for 12 hours to obtain pretreated copper particles.
The filtration under reduced pressure was performed by reducing the pressure of the 5C filter paper Kiriyama funnel with a diaphragm pump. Further, the drying under reduced pressure was performed by putting the filtered copper particles in a vacuum oven and reducing the pressure of the oven with an oil pump.

<Infrared absorption (IR) spectrum analysis>
Measuring instrument model: FT / IR-6100 manufactured by JASCO Corporation
Measuring method: ATR method, decomposition; 2 cm ⁻¹ , integration count: 80 times

<Laser etching processing>
Laser etching was performed on the cured copper film obtained by curing the copper paste composition using the following apparatus. The processing conditions were adjusted, and the substrate was processed under conditions where there was no residue of the copper paste composition and fine wiring could be formed, and the substrate damage was the least.
RICOH LA-1100 [manufactured by Ricoh Industrial Solutions Co., Ltd.], laser used; fiber laser (50 ps to 1 ns), wavelength: 1064 nm

<Electrical conductivity evaluation>
The conductivity was evaluated by the resistance value and volume resistivity measured as follows.
First, a cured copper film having a film thickness of 6 to 8 μm was formed on the substrate, and the cured copper film-coated substrate was cut into a sample plate having a width of 0.5 mm and a length of 8.0 mm. The copper cured film of the sample plate was laser-etched to form nine copper wirings having a line width of 0.02 to 0.04 mm and a length of 5.0 mm on the sample plate.
The resistance value of the copper cured film on the sample plate before laser etching processing and the copper wiring after processing was measured using a digital multimeter. Furthermore, the volume resistivity was calculated from the resistance value by the following formula (2).
The lower the resistance value and volume resistivity, the easier the current flows, that is, the higher the conductivity.
The measurement models and measurement conditions are shown below.
Measuring instrument model: Digital multimeter PC720M [manufactured by Sanwa Denki Keiki Co., Ltd.]
Measurement conditions: Two-terminal method Volume resistivity;
[Volume resistivity (Ω · cm)] = [{film thickness (cm)} × {line width (cm)} ÷ {length (cm)}] × [number (−)] × [resistance value (Ω) ] (2)
In addition, the line width and length of Formula (2) are the width and length of a sample board in the case of the copper cured film before a process, and in the case of the copper wiring after a process, a line width is one wiring. It is the width and the length is 5.0 mm which is one length. The resistance value of the copper wiring after processing was measured by pressing a digital multi-tester probe (φ about 1 mm) against both ends of nine copper wirings having a line width of 0.02 to 0.04 mm and a length of 5.0 mm. This was conducted together.

Example 1
<Production of surface-coated copper particles (A); (A1)>
[Step 1]
200 g of the pretreated copper particles 1 was put into 600 g of water, and nitrogen bubbling was performed for 30 minutes while stirring at 25 ° C. After heating up this copper particle containing water to 60 degreeC, 400 g of 50 mass% ethylenediamine aqueous solution was dripped at the said copper particle containing water at 30 mL / min, and it stirred for 40 minutes, hold | maintaining 60 degreeC. Stirring was performed using a mechanical stirrer at a rotation speed of 150 rpm. Hereinafter, stirring was performed at the same rotational speed using the same stirring device.
[Step 2]
Stirring was stopped and the mixture was allowed to stand for 5 minutes, and then about 800 g of the supernatant was extracted and removed. Subsequently, 800 g of isopropanol was added as a washing solvent to the precipitate, and the mixture was stirred at 30 ° C. for 3 minutes. Stirring was stopped and the mixture was allowed to stand for 5 minutes, and then about 800 g of the supernatant was extracted and removed to obtain Intermediate 1.
[Step 3]
After adding 1000 g of an isopropanol solution of 2% by mass myristic acid to Intermediate 1, the mixture was stirred at 30 ° C. for 30 minutes.
[Step 4]
After stopping the stirring, the isopropanol solution of myristic acid was removed by filtration under reduced pressure to obtain Intermediate 2. The vacuum filtration was performed by reducing the pressure of the 5C filter paper Kiriyama funnel with a diaphragm pump.
[Step 5]
The intermediate body 2 was dried under reduced pressure at 25 ° C. for 3 hours to obtain surface-coated copper particles (A1). The drying under reduced pressure was performed by placing the intermediate 2 in a vacuum oven and reducing the pressure of the oven with an oil pump.

The IR spectrum of the surface of the obtained (A1) was measured. An IR spectrum diagram of (A1) is shown in FIG.
When ethylenediamine used for coating is measured alone, the peak of N—H bending vibration appears at 1598 cm ⁻¹ (FIG. 2), whereas the N—H bending angle observed in the surface-coated copper particles. The peak of vibration is shifted to a low wavenumber side of 1576 cm ⁻¹ , indicating that ethylenediamine is coordinated on the copper particle surface. In FIG. 1, the peak of C═O stretching vibration of myristic acid is not observed at 1700 cm ^−1, and the peak of carboxylate anion (—COO ⁻ ) is observed near 1400 cm ⁻¹ , and myristic acid is an amine. It shows that the compound exists by electrostatic interaction.
From the IR spectrum, it can be determined that both the ethylenediamine of the first coating layer and the myristic acid of the second coating layer are bonded by chemical bonds to form each coating layer.

<Manufacture of copper paste composition>
(A1) 100 g, 62.7 mass% ethyl carbitol solution of resol type phenol resin as a binder [PL-5208, manufactured by Gunei Chemical Industry Co., Ltd.] 27 g [(B); 17 g phenol resin, solvent (D1); Ethyl carbitol 10 g] and 1.4 g of 1,4-phenylenediamine as an antioxidant (C) were mixed. Next, using a planetary mixer [ARV-310, manufactured by Shinkey Co., Ltd.], the mixture was stirred at room temperature for 30 seconds at a rotation speed of 1500 rpm to perform primary kneading.
Next, secondary kneading was performed using a three-roll mill [EXAKT-M80S, manufactured by Nagase Screen Printing Laboratory Co., Ltd.] five times under conditions of room temperature and a distance between rolls of 5 μm.
Next, 2.6 g of ethyl carbitol acetate as a solvent (D2) was added to the kneaded product obtained by the secondary kneading, and the mixture was stirred for 90 seconds at a rotation speed of 1000 rpm at room temperature under a vacuum condition using a planetary mixer. A copper paste composition was produced by foam kneading.
The solvent (D) of Example 1 is a mixed solvent of the above (D1) and (D2). Table 2 shows the blending ratio of each component in the copper paste composition. Here, (A1) + (B) + (C) + (D1) + (D2) is the total amount of the copper paste composition, and (B) + (D1) and (D1) + (D2) in the table ) Values are shown for reference.

<Formation of cured copper film, preparation of sample plate and conductivity evaluation>
The obtained copper paste composition was applied to a pattern of width × length × thickness = 1 cm × 3 cm × 30 μm on a PET film (Lumirror S10, film thickness 125 μm, manufactured by Toray Industries, Inc.) using a metal mask. . A cured copper film was manufactured by heating the PET film coated with the pattern at 120 ° C. for 30 minutes.
The obtained copper cured film-coated PET film was cut into the above-mentioned dimensions before processing, “line width 0.5 mm × length 8.0 mm” with a cutter to prepare a sample plate. The film thickness of the sample plate was 7.1 μm. The resistance value of the copper cured film of the sample plate was measured with the digital multimeter PC720M. Furthermore, the volume resistivity was calculated by the formula (2). Table 2 shows the resistance value and volume resistivity of the sample plate as a result before processing by laser etching. Moreover, the optical microscope image of this copper cured film surface is shown in FIG.

<Formation of copper wiring by laser etching and conductivity evaluation>
The copper cured film of the sample plate is laser-etched under the following conditions with the above RICOH LA-1100 to form a fine copper wiring with “line (L) + space (S)” of 40 μm, and the resistance value is Measured with a digital multimeter PC720M. Furthermore, the volume resistivity was calculated by the formula (2). Table 2 shows the resistance value and volume resistivity of the copper wiring as results after processing by laser etching. Moreover, the optical microscope image of the obtained copper wiring surface is shown in FIG. It can be seen from FIG. 4 that good fine wiring with L / S = 30.2 / 9.8 μm is obtained.
(Laser etching conditions)
Output: 4.3W
Number of scans: 2pass
Scanning speed: 3000 mm / s
Processing pitch: 40 μm {Line (L) width + Space (S) width}

(Example 2)
Surface-coated copper particles (A) (A2) were produced in the same manner as in Example 1 except that the copper particles 2 were used as the raw material copper particles.
Except for using (A2), a cured copper film and a copper wiring were formed in the same manner as in Example 1, and the conductivity was evaluated. Fine wiring with L / S = 31.2 / 8.8 μm was obtained. The results are shown in Table 2.

(Example 3)
Surface-coated copper particles (A) (A3) were produced in the same manner as in Example 1 except that copper particles 3 were used as the raw material copper particles.
Except for using (A3), a cured copper film and a copper wiring were formed in the same manner as in Example 1, and the conductivity was evaluated. Fine wiring with L / S = 30.5 / 9.5 μm was obtained. The results are shown in Table 2.

(Comparative Example 1)
Surface-coated copper particles (CA1) were produced in the same manner as in Example 1 except that the copper particles 4 were used as the raw material copper particles.
A cured copper film and a copper wiring were formed in the same manner as in Example 1 except that (CA1) was used and the laser etching conditions were changed as follows, and the conductivity was evaluated. The results are shown in Table 2. Moreover, the optical microscope image of the obtained copper cured film is shown in FIG. 5, and the optical microscope image of the copper wiring surface is shown in FIG.
The resistance value “OL” in Table 2 indicates that the measurable upper limit value of the device exceeds 6.0 × 10 ⁶ Ω. A volume resistivity exceeding 1.6 × 10 ^{2 in} Table 2 indicates that the resistance value exceeds the value calculated using the upper limit value (the same applies hereinafter).
As can be seen from FIG. 6, a wiring with L / S = 23.4 / 16.6 μm is obtained, but the wiring has a rough shape and is inferior in laser etching processability as compared with Example 1.
Output: 7.0W
Number of scans: 2pass
Scanning speed: 2000mm / s
Processing pitch: 40 μm {Line (L) width + Space (S) width}

(Comparative Example 2)
Surface-coated copper particles (CA2) were produced in the same manner as in Comparative Example 1 except that the copper particles 5 were used as the raw material copper particles.
A cured copper film and a copper wiring were formed in the same manner as in Comparative Example 1 except that (CA2) was used, and the conductivity was evaluated. A wiring showing clear L / S was not obtained. The results are shown in Table 2.

(Comparative Example 3)
A cured copper film and a copper wiring were formed in the same manner as in Example 1 except that only the pretreated copper particles 1 were used instead of the surface-coated copper particles, and the conductivity was evaluated. A wiring with L / S = 31.0 / 9.0 μm was obtained. The results are shown in Table 2.

In Examples 1 to 3, both the cured copper film before laser etching and the copper wiring after processing have a low resistance value and volume resistivity, and show good conductivity. In addition, the decrease in conductivity before and after processing is small, and the oxidation resistance during laser etching is excellent.
On the other hand, in Comparative Examples 1 and 2, the conductivity of the cured copper film before processing is excellent, but the conductivity after processing is extremely lowered. The reason for this is that the surface coated copper particles are oxidized by the heat generated during laser irradiation because the particle diameter of the surface coated copper particles is large and the laser output required for laser etching must be increased. Can be considered. That is, Comparative Examples 1 and 2 are extremely inferior in oxidation resistance during laser etching.
Comparative Example 3 had a resistance value of O.D. before laser etching. L. It became. This is presumably because the copper particles were not surface-coated, and copper oxidation proceeded by heating at 120 ° C. when forming the cured film.

Claims (1)

A copper paste composition containing surface-coated copper particles (A), a binder (B), an antioxidant (C), and a solvent (D),
The raw material copper particles before surface coating for the surface coated copper particles (A) have an average particle diameter D50 of 0.5 to 2 μm, and the content of particles having a particle diameter of 3 μm or more in the raw material copper particles is 5 mass. % Or less,
The surface-coated copper particles (A) include a first coating layer of an amine compound represented by formula (1) that is bonded to copper on the surface of the raw material copper particles by chemical bonds and / or physical bonds, Having a second coating layer of an aliphatic monocarboxylic acid having 8 to 20 carbon atoms bonded to the amine compound by a chemical bond on one coating layer;
The copper paste composition is based on 100 parts by mass of the surface-coated copper particles (A), 10-30 parts by mass of the binder (B), 0.1-7.0 parts by mass of the antioxidant (C), And 1-30 parts by mass of the solvent (D),
Copper paste composition for laser etching.
[In the formula (1), m is an integer of 0 to 3, n is an integer of 0 to 2, and when n = 0, m is any of 0 to 3, when n = 1 or n = 2, m is any one of 1-3. ]