JP7056552B2 - Conductive coating and conductive paste for laser etching processing - Google Patents

Description

INDUSTRIAL APPLICABILITY The present invention relates to a method for producing a conductive pattern capable of producing a conductive pattern having a high arrangement density in the plane direction, and a conductive paste or a film (or a thin film) obtained from the conductive paste that can be suitably used for this manufacturing method. ). More specifically, the present invention is a conductive film provided to obtain a conductive pattern having a high arrangement density in the planar direction by removing a part of the conductive film (or a conductive thin film) by a luminous flux of excitation light. Regarding. The conductive pattern of the present invention can typically be used for electrode circuit wiring of a transparent touch panel.

In recent years, the performance and miniaturization of electronic devices equipped with transparent touch panels such as mobile phones, notebook computers, and electronic books have been rapidly advancing. In order to improve the performance and miniaturization of these electronic devices, in addition to miniaturization, high performance, and improvement of the degree of integration of the mounted electronic components, it is required to increase the density of the electrode circuit wiring that joins these electronic components to each other. Has been done. In recent years, in addition to the resistance film method, which has a small number of electrode circuit wirings, as a transparent touch panel method, the capacitance method, which has a dramatically large number of electrode circuit wirings, has rapidly become widespread. There is a strong demand for higher density. In addition, in order to make the display screen larger and due to product design requirements, there is a demand to make the frame where the electrode circuit wiring is arranged narrower, and from this point of view, the high density of the electrode circuit wiring is also required. Is required. In order to satisfy the above requirements, there is a demand for a technique capable of arranging electrode circuit wiring at a higher density than before.

The arrangement density of the electrode circuit wiring in the frame portion of the resistance film type transparent touch panel is such that the width of the line and the space in the plane direction are each 200 μm (hereinafter, abbreviated as L / S = 200/200 μm) or more. It has been conventionally performed to form this by screen printing of a conductive paste. In the capacitive touch panel, the L / S requirement is about 100/100 μm or less, and in some cases, the L / S is required to be 50/50 μm or less. The situation is becoming difficult to deal with.

A photolithography method is an example of a candidate for an electrode circuit wiring forming technique that replaces screen printing. By using the photolithography method, it is sufficiently possible to form thin lines having an L / S of 50/50 μm or less. However, the photolithography method also has a problem. The most typical example of the photolithography method is a method using a photosensitive resist, and generally, a photosensitive resist is applied to a copper foil portion of a surface substrate on which a copper foil layer is formed, and a photomask or laser light is used. A desired pattern is exposed by a method such as direct drawing, a photosensitive resist is developed, and then a copper foil portion other than the desired pattern is dissolved and removed with a chemical to form a fine line pattern of the copper foil. For this reason, the environmental load due to the waste liquid treatment is large, the process is complicated, and there are many problems such as production efficiency, cost, and poor appearance due to copper foil oxidation.

In the photolithography method, there is also a method that does not use a photosensitive resist. For example, in Patent Documents 1 and 2, a dry coating film is formed by using a conductive paste, and a dry coating film is directly drawn on the dry coating film by using a laser beam. Disclosed is a technique for fixing an irradiated portion to a substrate, developing and removing an unirradiated portion, and forming a desired pattern. Compared with a general photolithography method, such a method simplifies the process because it does not use a photosensitive resist, but it is a photolithography method using a conventionally known photosensitive resist. Similarly, there is a problem of developing waste liquid treatment because the developing process of the wet process is required, and since glass frit and nano-sized silver powder are used as the components of the conductive paste, a high temperature of 400 ° C or higher is required in the firing process. Therefore, there is a problem that a large amount of energy is required, and there is a problem that the base material that can be used is limited to those that can withstand the firing process at a high temperature of 400 ° C. or higher. Furthermore, it must be said that the process is complicated and the production efficiency is unsuitable.

Under the above circumstances, as an example of a candidate for an electrode circuit wiring forming technique that replaces screen printing, a part of the conductive film is removed by a luminous flux of excitation light whose technique is disclosed in Patent Documents 3 and 4. The method, the so-called laser etching method, has been attracting attention in recent years. By using the laser etching method, it is sufficiently possible to form fine wires having an L / S of 50/50 μm or less. The laser etching method is a method in which a layer consisting of a binder resin and conductive powder (hereinafter referred to as a conductive thin film) is formed on an insulating base material, and a part thereof is removed from the insulating base material by laser light irradiation. That is.

There is a strong demand for further thinning of the laser etching method, and the etching width tends to be narrower as L / S = 30/30 μm, 20/20 μm, and 15/15 μm. In addition, the distance to remove the coating film by laser etching has become longer due to the larger screen of the touch panel, and the required performance required for the conductive paste for laser etching processing is increasing day by day, and the circuit disconnection that has not been realized until now. , Defects due to short circuit have become a big problem, and improvement is required. In order to obtain high-quality fine lines by the laser etching method, the quality of the conductive film immediately before laser etching is important, and not only the conductive paste itself but also the printing drying and curing process must be sufficiently controlled.

Japanese Unexamined Patent Publication No. 2010-237573 Japanese Unexamined Patent Publication No. 2011-181338 Japanese Patent Application No. 2012-161485 Japanese Unexamined Patent Publication No. 2014-2992

An object of the present invention is to provide a conductive paste for laser etching processing capable of suppressing defects due to circuit disconnection or short circuit even in a difficult pattern such as a narrow laser etching width and a long laser etching distance. An object of the present invention is to realize a conductive film having characteristics necessary for obtaining high-quality fine lines in a laser etching method.

As a result of diligent studies, the present inventors have found a conductive film for laser etching processing that is most suitable for the laser etching method. That is, the invention of the present application has the following configuration.

[1] In a conductive film composed of a conductive composition composed of a conductive filler and a binder resin, the presence density of ring-shaped dent defects having a diameter of 50 μm or less on the surface of the film is 50 pieces / cm2 or less. Characteristic conductive film.
[2] The conductive film according to [1], wherein the surface roughness Ra of the portion of the conductive film having no ring-shaped dent is 0.1 or more and 1.0 μm or less.
[3] The conductive film according to [1] or [2], wherein the average film thickness of the conductive film is 2 μm or more and 20 μm or less.
[4] The conductive composition contains at least silver particles having an average particle diameter of 0.3 μm or more and 6 μm or less, silicon dioxide particles having an average particle diameter of 5 nm or more and 200 nm or less, and a polymer binder resin. The conductive film according to any one of [1] to [3], which is characterized in that it does not contain a solvent.
[5] The conductive composition contains at least silver particles having an average particle diameter of 0.3 μm or more and 6 μm or less, carbon particles having an average particle diameter of 5 nm or more and 200 nm or less, and a polymer binder resin, substantially. The conductive film according to any one of [1] to [3], which is characterized by containing no solvent.
[6] The conductive composition contains at least silver particles having an average particle diameter of 0.3 μm or more and 6 μm or less, ion-catching agent particles having an average particle diameter of 50 nm or more and 3000 nm or less, and a polymer binder resin. The conductive film according to any one of [1] to [3], which is characterized by containing no solvent.
[7] A method for forming an electric wiring, which comprises a process of removing a part of the conductive film according to any one of [1] to [6] by a luminous flux of excitation light.

[8] At least a polymer binder resin (A), a metal powder (B) having an average particle size of 0.3 μm or more and 6 μm or less, an organic solvent (C), and silicon dioxide particles having an average particle size of 5 nm or more and 200 nm or less (D). ) Is contained in the conductive paste for laser etching processing.
[9] The binder resin (A) is one or a mixture of two or more selected from the group consisting of polyester resin, polyurethane resin, epoxy resin, phenoxy resin, vinyl chloride resin, and fibrous derivative resin. The conductive paste for laser etching processing according to [8].
[10] The laser etching according to [8] or [9], wherein the binder resin (A) has a number average molecular weight of 5,000 to 60,000 and a glass transition temperature of less than 120 ° C. Conductive paste for processing.
[11] The solvent is a mixture of at least two solvents having different boiling points, and the boiling point of the first solvent, which accounts for 45 to 90% by mass of the total amount of the solvent, is 200 ° C. or higher and 270 ° C. or lower, and the second. The boiling point of the solvent is lower than the boiling point of the first solvent by 10 ° C. or more, and is 55 to 10% by mass of the total amount of the solvent. Conductive paste.
[12] The conductive paste for laser etching processing according to any one of [8] to [11], wherein the acid value of the binder resin (A) is less than 200 equivalents / 106 g.
[13] The conductive paste for laser etching processing according to any one of [8] to [12], wherein the number of coarse silver particles of 15 μm or more is 100 or less per 1.0 g of the paste.

[14] Metal powder (B) having an average particle diameter of at least 0.3 μm or more and 6 μm or less, carbon particles (E) having an average particle diameter of 5 nm or more and 200 nm or less, a polymer binder resin (A), and a solvent (C). A conductive paste for laser etching processing, which is characterized by containing.
[15] The binder resin (A) is one or a mixture of two or more selected from the group consisting of polyester resin, polyurethane resin, epoxy resin, phenoxy resin, vinyl chloride resin, and fibrous derivative resin. The conductive paste for laser etching processing according to [14].
[16] The laser etching according to [14] or [15], wherein the binder resin (A) has a number average molecular weight of 5,000 to 60,000 and a glass transition temperature of less than 120 ° C. Conductive paste for processing.
[17] The solvent (C) is a mixture of at least two solvents having different boiling points, and the boiling point of the first solvent, which accounts for 45 to 90% by mass of the total amount of the solvent, is 200 ° C. or higher and 270 ° C. or lower. The laser according to any one of [14] to [16], wherein the boiling point of the second solvent is 10 ° C. or more lower than the boiling point of the first solvent, and is 55 to 10% by mass of the total amount of the solvent. Conductive paste for etching.
[18] The conductive paste for laser etching processing according to any one of [14] to [17], wherein the acid value of the binder resin (A) is less than 200 equivalents / 106 g.
[19] The conductive paste for laser etching processing according to any one of [14] to [18], wherein the number of coarse silver particles of 15 μm or more is 100 or less per 1.0 g of the paste.

[20] Silver particles (A) having an average particle size of at least 0.3 μm or more and 6 μm or less, and carbon (E) or silicon dioxide particles (D) having an average particle size of 5 nm or more and 200 nm or less.
Inorganic particles (H) with an average particle size of 0.1 μm or more and 3 μm or less
Polymer binder resin (A),
Solvent (C)
A conductive paste for laser etching processing, which is characterized by containing.
[21] The binder resin (A) is one or a mixture of two or more selected from the group consisting of polyester resin, polyurethane resin, epoxy resin, phenoxy resin, vinyl chloride resin, and fibrous derivative resin. The conductive paste for laser etching processing according to the feature [20].
[22] The laser etching process according to [20 or [21], wherein the binder resin (A) has a number average molecular weight of 5,000 to 60,000 and a glass transition temperature of less than 120 ° C. For conductive paste.
[23] The solvent is a mixture of at least two kinds of solvents having different boiling points, and the boiling point of the first solvent occupying 45 to 90% by mass of the total amount of the solvent is 200 ° C. or higher and 270 ° C. or lower, and the second The boiling point of the solvent according to any one of [20] to [22], which is 10 ° C. or more lower than the boiling point of the first solvent and is 55 to 10% by mass of the total amount of the solvent. Conductive paste.
[24] The conductive paste for laser etching processing according to any one of [20] to [23], wherein the acid value of the binder resin (A) is less than 200 equivalents / 106 g.
[25] The conductive paste for laser etching processing according to any one of [20] to [24], wherein the number of coarse silver particles of 15 μm or more is 100 or less per 1.0 g of the paste.

The present invention relates to a conductive film for laser etching processing. The present inventors specified a specific film expression when developing a fine line forming technique using a so-called laser etching method in which a silver paste film coated and dried on a substrate is partially removed by laser light. It was found that the pattern was observed, and the place where the fine line was broken after laser etching was that when the laser light passed through the specific pattern part, the laser light was partially scattered and the line width was wider than originally desired to be cut. It was found that the paste layer was ablated, which resulted in the breakage of the fine lines. The particular pattern consists of a ring-shaped recess and a protrusion in the center of the ring. In such a pattern (hereinafter referred to as a ring-shaped dent), when the paste coating film is dried, the paste surface layer first changes from constant rate drying to reduced rate drying, and the path for the solvent to volatilize from the inside of the paste layer is closed, so that the paste is pasted. It is considered that the paste surface layer is lifted due to the increase in the internal pressure in the layer.

Drying of the conductive paste film is a composite system consisting of inorganic particles whose physical properties do not change directly in the drying process, a binder resin which is a dispersion medium whose physical properties change in the drying process, and a solvent. In such a case, the volatilization of the solvent in the lapse rate drying region is affected by the drying barrier created by the accumulation of inorganic particles at the same time as the diffusion in the dispersion medium layer, so that the drying path through which the solvent passes through the film is the apparent film thickness. It will be longer than that.
Therefore, the first method for reducing the ring-shaped dent defect, which is a problem of the present invention, is to set the drying conditions after reaching the reduced rate drying state to mild and dry at a low temperature for a sufficiently long time. be. By such a technique, it is possible to realize a conductive film having excellent laser etching processability, which has few ring-shaped dent defects, which is the object of the present invention.

On the other hand, taking a long drying time causes a problem in productivity. By preliminarily blending the conductive paste composition with a component that easily forms a drying path in the lapse rate drying process, the present inventors can obtain good quality without lowering the drying temperature in the lapse rate drying region. It has been found that the conductive coating material to have is realized.
In the present invention, silicon dioxide particles having an average particle diameter of 5 nm or more and 200 nm or less, carbon particles having an average particle diameter of 5 nm or more and 200 nm or less, and an average particle diameter of 50 nm or more and 3000 nm or less, which are added separately from the conductive particles, are added. The ion-catching agent particles of the above form a network in the dry coating film of the paste, form a path for solvent volatilization in the paste layer, and have an action of promoting diffusion. More preferably, by using a mixed solvent satisfying a specific condition as the solvent, the volatilization of the solvent is further promoted, and as a result, the movement of the solvent becomes smooth even after the paste coating film reaches the reduced rate drying. By combining such a method, a ring-shaped dent is reduced, and a suitable conductive film capable of suppressing a circuit disconnection defect in a pattern formed by laser etching processing with L / S = 50/50 μm or less is obtained. be able to.
Further, in this composition, the residual solvent is less likely to remain inside the coating film, and as a result, the adhesion is improved. In addition, since the residual solvent is rapidly volatilized during laser etching to prevent flushing due to its emission, a positive effect on productivity can be further obtained.

It is a reflection image, a concave-convex image, and a cross-sectional profile of a ring-shaped dent generated in a conductive thin film obtained by screen-printing a silver paste and drying it with a laser microscope. It is a schematic diagram of the laser etching processing aptitude evaluation test piece.

The conductive film of the present invention is composed of a conductive composition composed of a conductive filler and a binder resin, and the presence density of ring-shaped dent defects having a diameter of 50 μm or less on the surface of the film is 50 pieces / cm2 or less. Characteristically, the surface roughness Ra of the portion of the conductive film having no ring-shaped dent is 0.1 or more and 1.0 μm or less, and more preferably the average film thickness of the conductive film is 2 μm or more and 20 μm or less. be.
FIG. 1 shows an example of the ring-shaped dent defect in the present invention. The defect of the ring-shaped dent is that the portion where the film thickness is reduced from the surroundings forms a ring shape, and the center is surrounded by the ring and has a caldera volcanic cross-sectional shape. Although the process in which the defects of this form occur has not been observed in detail, it is considered to occur in the drying process of the conductive film because it is not observed on the surface of the undried film immediately after printing.

The laser etching method is a method of forming fine lines by removing an unnecessary portion of a conductive film obtained by applying and drying a conductive paste by laser ablation. It is easy to understand that if the coating film before laser etching has defects such as "bubble marks" and "missing" that the conductive film does not exist, that part becomes a disconnection defect after etching. can. The defect of the ring-shaped dent is a relatively large unevenness on the surface of the coating film, but there is not necessarily a portion where the conductive film is not completely present. Nevertheless, the portion where the ring-shaped dent defect is present tends to break the fine wire after the laser etching process.
It is considered that this phenomenon is caused by the fact that the central convex part of the ring-shaped dent defect is placed in a semi-insulated state in the coating film by the surrounding ring-shaped dent, and heat is accumulated in the central part, causing abnormal ablation. Be done.

Therefore, in order to obtain good laser etching properties, it is better that the number of ring-shaped dent defects existing in the conductive film is small, and it is essential that the abundance density is 50 pieces / cm2 or less, preferably 20 pieces. Pieces / cm2 or less, more preferably 8 pieces / cm2 or less, still more preferably 3 pieces / cm2 or less.
Further, in the present invention, the surface roughness Ra of the portion where the ring-shaped dent does not exist is preferably 0.1 or more and 1.0 μm or less, more preferably 0.1 or more and 0.8 μm or less, and further preferably 0. It is 1 μm or more and 0.6 μm or less.
The average film thickness of the conductive film of the present invention is 2 μm or more and 20 μm or less, preferably 3 μm or more and 14 μm or less, and more preferably 4 μm or more and 11 μm or less.

In the conductive film having few ring-shaped dent defects of the present invention, a conductive paste composed of a conductive filler, a binder resin and a solvent is applied at a low temperature for a sufficiently long time, for example, at about 60 ° C to 100 ° C for 60 to 300 minutes. It can be realized by drying and solidifying under some conditions. However, in the actual manufacturing process, it is virtually impossible to spend such a long time in the drying process of the conductive paste.

In the present invention, at least one of the methods (1) to (3) shown below can be used to obtain a conductive film having few ring-shaped dent defects, which is the object of the present invention.
(1) A method in which a conductive paste containing a solvent is used for silver particles having an average particle size of at least 0.3 μm or more and 6 μm or less, silicon dioxide particles having an average particle size of 5 nm or more and 200 nm or less, and a polymer binder resin.
(2) A method in which a conductive paste containing a solvent is used for silver particles having an average particle diameter of at least 0.3 μm or more and 6 μm or less, carbon particles having an average particle diameter of 5 nm or more and 200 nm or less, and a polymer binder resin.
(3) A method of using silver particles having an average particle diameter of 0.3 μm or more and 6 μm or less, ion-catching agent particles having an average particle diameter of 50 nm or more and 3000 nm or less, and a conductive paste containing a solvent in a polymer binder resin.

The conductive paste of the present invention is at least (A) a polymer binder resin,
(B) Metal powder having an average particle diameter of 0.3 μm or more and 6 μm or less (C) Organic solvent (D) Contains silicon dioxide particles having an average particle diameter of 5 nm or more and 200 nm or less. In this composition, the silicon dioxide particles form a network in the paste dry coating film and have an action of promoting solvent volatilization in the paste layer. More preferably, by using a mixed solvent satisfying a specific condition as the solvent, the volatilization of the solvent is further promoted, and as a result, the movement of the solvent becomes smooth even after the paste coating film reaches the reduced rate drying. As a result, the ring-shaped dent is reduced, and it is possible to suppress the disconnection defect of the circuit in the pattern formed by the laser etching process of L / S = 50/50 μm or less. Further, in this composition, the residual solvent is less likely to remain inside the coating film, and as a result, the adhesion is improved.

The conductive paste of the present invention has at least metal particles (B) having an average particle diameter of 0.3 μm or more and 6 μm or less.
Carbon particles (E) with an average particle diameter of 5 nm or more and 200 nm or less,
Polymer binder resin (A),
Organic solvent (C)
Contains. In this composition, the carbon particles form a network in the dry coating film and have an action of promoting solvent volatilization in the paste layer. More preferably, by using a mixed solvent satisfying a specific condition as the solvent, the volatilization of the solvent is further promoted, and as a result, the movement of the solvent becomes smooth even after the paste coating film reaches the reduced rate drying. As a result, the ring-shaped dent is reduced, and it is possible to suppress the disconnection defect of the circuit in the pattern formed by the laser etching process of L / S = 50/50 μm or less. Further, in this composition, the residual solvent is less likely to remain inside the coating film, and as a result, the adhesion is improved.

The conductive paste of the present invention comprises at least (B) silver particles having an average particle size of 0.3 μm or more and 6 μm or less, and (G) carbon or silicon dioxide particles having an average particle size of 5 nm or more and 200 nm or less.
(H) Inorganic particles with an average particle diameter of 0.1 μm or more and 3 μm or less,
(A) Polymer binder resin,
(E) Contains a solvent. In this composition, in addition to (G) carbon or silicon dioxide particles, (H) inorganic particles having an average particle diameter of 0.1 μm or more and 3 μm or less form a network in the dry coating film of the paste and form a network in the paste layer. It has the effect of promoting solvent volatilization. More preferably, by using a mixed solvent satisfying a specific condition as the solvent, the volatilization of the solvent is further promoted, and as a result, the movement of the solvent becomes smooth even after the paste coating film reaches the reduced rate drying. As a result, the ring-shaped dent is reduced, and it is possible to suppress the disconnection defect of the circuit in the pattern formed by the laser etching process of L / S = 50/50 μm or less. Further, in this composition, the residual solvent is less likely to remain inside the coating film, and as a result, the adhesion is improved. In addition, since the residual solvent is rapidly volatilized during laser etching to prevent flushing due to its emission, a positive effect on productivity can be further obtained.

The type of the binder resin (A) in the present invention is not particularly limited as long as it is a thermoplastic resin, but polyester resin, epoxy resin, phenoxy resin, butyral resin, polyamide resin, polyamideimide resin, polycarbonate resin, polyurethane resin, phenol resin, and the like. Acrylic resin, polystyrene, styrene-acrylic resin, styrene-butadiene copolymer, phenol resin, polyethylene resin, polycarbonate resin, phenol resin, alkyd resin, styrene-acrylic resin, styrene-butadiene copolymer resin, polysulfone resin, poly Examples thereof include ether sulfone resin, vinyl chloride-vinyl acetate copolymer resin, ethylene-vinyl acetate copolymer, polystyrene, silicone resin, fluororesin and the like, and these resins can be used alone or as a mixture of two or more kinds. Can be used. Among these, one or a mixture of two or more selected from the group consisting of polyester resin, polyurethane resin, epoxy resin, phenoxy resin, vinyl chloride resin, and fibrous derivative resin is preferable. Further, among these resins, at least one of a polyester resin, a polyurethane resin containing a polyester component as a copolymerization component (hereinafter, may be referred to as a polyester polyurethane resin), an epoxy resin, and a phenoxy resin can be used. More preferable as a binder resin.

One of the advantages of using the polyester resin as the binder resin in the present invention is the high degree of freedom in molecular design. The dicarboxylic acid and glycol components constituting the polyester resin can be selected and the copolymerization component can be freely changed, and it is easy to add a functional group in the molecular chain or to the end of the molecule. Therefore, the characteristics of the resin such as the glass transition temperature of the obtained polyester resin and the affinity with the base material and other components blended in the conductive paste can be appropriately adjusted.

Examples of the dicarboxylic acid that can be used as a copolymerization component of the polyester resin used as the binder resin in the present invention include aromatic dicarboxylic acids such as terephthalic acid, isophthalic acid, orthophthalic acid, and 2,6-naphthalenedicarboxylic acid. An aliphatic dicarboxylic acid such as succinic acid, glutaric acid, adipic acid, sebacic acid, dodecandicarboxylic acid, and azelaic acid, a dibasic acid having 12 to 28 carbon atoms such as dimeric acid, 1,4-cyclohexanedicarboxylic acid, 1,3 -Cyclohexanedicarboxylic acid, 1,2-cyclohexanedicarboxylic acid, 4-methylhexahydrohydride phthalic acid, 3-methylhexahydrohydride phthalic acid, 2-methylhexahydrohydride phthalic acid, dicarboxyhydrogenated bisphenol A, dicarboxyhydrogen Examples thereof include alicyclic dicarboxylic acids such as added bisphenol S, dimer acid, hydrogenated dimer acid, hydrogenated naphthalenedicarboxylic acid and tricyclodecanedicarboxylic acid, and hydroxycarboxylic acids such as hydroxybenzoic acid and lactic acid. Further, as long as the effects of the present invention are not impaired, trivalent or higher carboxylic acids such as trimellitic anhydride and pyromellitic anhydride, unsaturated dicarboxylic acids such as fumaric acid, and / or 5-sulfoisophthalic acid sodium salts and the like. Dicarboxylic acid containing a metal sulfonate metal base may be used in combination as a copolymerization component.

Examples of polyols that can be used as a copolymerization component of the polyester resin used as the binder resin in the present invention include ethylene glycol, propylene glycol, 1,3-propanediol, 1,4-butanediol, and 1,5-. Pentandiol, neopentaneglycol, 1,6-hexanediol, 3-methyl-1,5-pentanediol, 2-methyl-1,5-pentanediol, 2-methyl-1,3-propanediol, 2,2 -Diethyl-1,3-propanediol, 2-butyl-2-ethyl-1,3-propanediol, 1,9-nonanediol, aliphatic diols such as 1,10-decanediol, 1,4-cyclohexanedi Examples thereof include alicyclic diols such as methanol, 1,3-cyclohexanedimethanol, 1,2-cyclohexanedimethanol, and dimerdiol. Further, a trivalent or higher-valent polyol such as trimethylolethane, trimethylolpropane, glycerin, pentaerythritol, and polyglycerin may be used in combination as a copolymerization component as long as the effects of the invention are not impaired.

The polyester resin used as the binder resin in the present invention contains 10 mol of the aliphatic dicarboxylic acid among all the acid components constituting the polyester resin from the viewpoints of adhesion, compatibility with other resins used in combination, and thermal shock resistance. % Or more is preferably copolymerized, more preferably 20 mol% or more, still more preferably 30 mol% or more. If the copolymerization ratio of the aromatic dicarboxylic acid component is too high, the glass transition temperature of the obtained polyester resin becomes 60 ° C or higher, and the storage stability deteriorates due to the deterioration of compatibility with the resin used in combination, and the straight line of laser etching processing. There is a possibility that the property will be reduced and the adhesion of the obtained conductive thin film after laser etching will be reduced.

It is also a preferred embodiment to use a polyurethane resin as the binder resin in the present invention. As in the case of polyester resin, for polyurethane resin, glass transition is performed by selecting an appropriate component as a copolymerization component constituting the polyurethane resin and by imparting a functional group in the molecular chain or to the end of the molecule. The characteristics of the resin such as the temperature and the affinity with the base material and other components blended in the conductive paste can be appropriately adjusted.

The copolymerization component of the polyurethane resin is also not particularly limited, but a polyester polyurethane resin using a polyester polyol as a copolymerization component is preferable from the viewpoint of design freedom, moisture and heat resistance, and maintenance of durability. Preferable examples of the polyester polyol include those that are polyols among the polyester resins that can be used as the binder resin in the present invention described above.

The polyurethane resin used as the binder resin in the present invention can be obtained, for example, by reacting a polyol with a polyisocyanate. Examples of the polyisocyanide that can be used as a copolymerization component of the polyurethane resin include 2,4-toluene diisocyanate, 2,6-toluene diisocyanate, p-phenylene diisocyanate, 4,4'-diphenylmethane diisocyanate, and m-phenylene diisocyanate. , 3,3'-dimethoxy-4,4'-biphenylene diisocyanate, 2,6-naphthalene diisocyanate, 3,3'-dimethyl-4,4'-biphenylene diisocyanate, 4,4'-diphenylene diisocyanate, 4,4 '-Diisocyanide diphenyl ether, 1,5-naphthalenediocyanide, m-xylene diisocyanate, isophorone diisocyanate, tetramethylene diisocyanate, hexamethylene diisocyanate, toluene diisocyanate, etc. It may be either. Further, as long as the effect of the present invention is not impaired, an isocyanate compound having a trivalent or higher valence may be used in combination as a copolymerization component.

The polyurethane resin used as the binder resin in the present invention can be copolymerized with a compound having a functional group capable of reacting with isocyanate, if necessary. As the functional group capable of reacting with isocyanate, a hydroxyl group and an amino group are preferable, and those having either one or both may be used. Specific examples thereof include dimethylol butanoic acid, dimethylol propionic acid, 1,2-propylene glycol, 1,2-butylene glycol, 1,3-butylene glycol, 2,3-butylene glycol, 2,2.
-Dimethyl-1,3-propanediol, 3-methyl-1,5-pentanediol, 2,2,4-trimethyl-1,3-pentanediol, 2-ethyl-1,3-hexanediol, 2,2 -Dimethyl-3-hydroxypropyl-2', 2'-dimethyl-3'-hydroxypropanol, 2-normalbutyl-2-ethyl-1,3-propanediol, 3-ethyl-1,5-pentanediol, 3-propyl-1,5-pentanediol, 2,2-diethyl-1,3-propanediol, 3-octyl-1,5-pentanediol, 3-phenyl-1,5-pentanediol, 2,5- Compounds having two hydroxyl groups in one molecule, such as dimethyl-3-sodiumsulfo-2,5-hexanediol and dimerdiol (for example, PRIPOOL-2033 manufactured by Unichema International), trimethylolethane, trimethylolpropane, etc. Alcohol having 3 or more hydroxyl groups in one molecule such as glycerin, pentaerythritol, polyglycerin, etc., aminoalcohol having one or more hydroxyl groups and amino groups in one molecule such as monoethanolamine, diethanolamine, triethanolamine, etc., ethylenediamine , 1,6-Hexanediamine, 1,8-octanediamine, 1,9-nonanediamine, 1,10-decanediamine, 1,11-undecanediamine, 1,12-dodecanediol and other aliphatic diamines and methaxylenediol amines. , 4,4'-Diaminodiphenylmethane, 3,4'-diaminodiphenyl ether, 4,4'-diaminodiphenyl ether and other aromatic diamines and the like, examples thereof include compounds having two amino groups in one molecule. The above-mentioned compound having a functional group capable of reacting with two or more isocyanates in one molecule having a number average molecular weight of less than 1,000 may be used alone or in combination of two or more without any problem.

The epoxy resin used as the binder resin in the present invention includes, for example, glycidyl ether types such as bisphenol A glycidyl ether, bisphenol S glycidyl ether, novolak glycidyl ether, and brominated bis, hexahydrophthalic acid glycidyl ester, and dimer acid glycidyl ester. Examples include glycidyl ester type, triglycidyl isocyanurate, or alicyclic or aliphatic epoxiside such as 3,4? Epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil. The above may be used together. Of these, bisphenol A glycidyl ether is preferable from the viewpoint of durability of the coating film, and those having two or more glycidyl ether groups in one molecule are more preferable.

The number average molecular weight of the binder resin in the present invention is not particularly limited, but the number average molecular weight is preferably 5,000 to 60,000, more preferably 10,000 to 40,000. If the number average molecular weight is too low, it is not preferable in terms of durability and moisture heat resistance of the formed conductive thin film. On the other hand, if the number average molecular weight is too high, the cohesive force of the resin is increased and the durability as a conductive thin film is improved, but the suitability for laser etching processing is significantly deteriorated.

The glass transition temperature of the binder resin in the present invention is preferably 120 ° C. or lower, more preferably 100 ° C. or lower. When the glass transition temperature is low, the linearity after laser etching becomes good, and the adhesion to the substrate after laser etching tends to be good.

The acid value of the binder resin in the present invention is not particularly limited, but if the acid value is too high, the water absorption of the formed conductive thin film becomes high, and the hydrolysis of the binder resin is promoted by the catalytic action of the carboxyl group. There is a possibility, which may lead to a decrease in the reliability of the conductive thin film. Hydrolysis is more pronounced at lower glass transition temperatures. Therefore, by setting the acid value of the binder resin to a low acid value, preferably less than 400 eq / ton, more preferably 300 eq / ton or less, the conductivity of the conductive thin film has both high reliability and laser etching linearity and adhesion. We have come to realize a sex paste.

The metal powder (B) used in the present invention includes precious metal powder such as silver powder, gold powder, platinum powder and palladium powder, base metal powder such as copper powder, nickel powder, aluminum powder and brass powder, and noble metal such as silver. Examples thereof include alloyed base metal powders and the like, for example, silver-coated copper powders. These metal powders may be used alone or in combination. Among these, in consideration of conductivity, stability, cost and the like, silver powder alone and / or silver-plated copper powder plated with silver or silver-plated alloy powder is preferable.

The shape of the metal powder used in the present invention is not particularly limited. Examples of conventionally known metal powder shapes include flake-like (flint-like), spherical, dendrite-like, and spherical primary particles described in JP-A-9-306240. There are three-dimensionally agglomerated shapes (aggregated) and the like, and from the viewpoint of laser etching properties, it is preferable to use spherical, agglomerated and flake-shaped metal powders, and more preferably flake-shaped and agglomerated-like. Is.

The center diameter (D50) of the metal powder used in the present invention is preferably 6 μm or less, more preferably 4 μm or less, and further preferably 2 μm or less. By using a metal powder having a center diameter of 6 μm or less, the fine wire shape of the laser-etched portion tends to be good. When a metal powder having a center diameter larger than 6 μm is used, the shape of the fine wires after the laser etching process deteriorates, and as a result, the fine wires may come into contact with each other, resulting in a short circuit. Furthermore, there is a possibility that the conductive thin film once peeled off and removed by laser etching processing will adhere to the processed portion again. The lower limit of the center diameter of the metal powder is not particularly limited, but from the viewpoint of cost, it is easy to aggregate when the particle size is fine, and as a result, it becomes difficult to disperse. Therefore, the center diameter is preferably 80 nm or more, preferably 0.3 μm or more. Is more preferable. When the center diameter is smaller than 80 nm, the cohesive force of the metal powder increases, the laser etching processing suitability deteriorates, and it is not preferable from the viewpoint of cost.

The center diameter (D50) is a particle size (μm) at which the cumulative value is 50% in the cumulative distribution curve (volume) obtained by some measuring method. In the present invention, the cumulative distribution curve is measured in the total reflection mode using a laser diffraction / scattering type particle size distribution measuring device (MICROTRAC HRA manufactured by Nikkiso Co., Ltd.).

The content of the metal powder is preferably 400 parts by mass or more and more preferably 560 parts by mass or more with respect to 100 parts by mass of the binder resin from the viewpoint of good conductivity of the formed conductive thin film. Further, the content of the component is preferably 1,900 parts by mass or less, and more preferably 1,230 parts by mass or less with respect to 100 parts by mass of the binder resin from the viewpoint of good adhesion to the substrate. Silver particles (silver powder) can be preferably used in the present invention.

The organic solvent (C) that can be used in the present invention is not particularly limited, but the boiling point is preferably 100 ° C. or higher and lower than 300 ° C., more preferably, from the viewpoint of keeping the volatilization rate of the organic solvent in an appropriate range. Has a boiling point of 150 ° C. or higher and lower than 280 ° C. The conductive paste of the present invention is typically prepared by dispersing a binder resin, a metal powder, an organic solvent and other components as necessary with a three-roll mill or the like, but the boiling point of the organic solvent is low at that time. If it is too much, there is a concern that the solvent will volatilize during dispersion and the composition ratio of the conductive paste will change. On the other hand, if the boiling point of the organic solvent is too high, a large amount of the solvent may remain in the coating film depending on the drying conditions, which may cause a decrease in the reliability of the coating film.

Further, as the organic solvent that can be used in the present invention, one in which the binder resin is soluble and the metal powder can be dispersed well is preferable. Specific examples include ethyl diglycol acetate (EDGAC), butyl glycol acetate (BMGAC), butyl diglycol acetate (BDGAC), cyclohexanone, toluene, isophorone, γ-butyrolactone, benzyl alcohol, Solvento 100, 150 manufactured by Exxon Chemical Co., Ltd., 200, a mixture of dimethyl esters of propylene glycol monomethyl ether acetate, adipic acid, succinic acid and glutaric acid (for example, DBE manufactured by DuPont Co., Ltd.), tarpionale and the like, among which a binder resin is blended. EDGAC, BMGAC, BDGAC and their mixed solvents are preferable from the viewpoints of excellent solubility of the components, moderate solvent volatility during continuous printing, and good suitability for printing by a screen printing method or the like.

The content of the organic solvent is preferably 5 parts by weight or more and 40 parts by weight or less, and more preferably 10 parts by weight or more and 35 parts by weight or less with respect to 100 parts by weight of the total weight of the paste. If the content of the organic solvent is too high, the viscosity of the paste becomes too low, and there is a tendency that sagging is likely to occur during fine line printing. On the other hand, if the content of the organic solvent is too low, the viscosity of the paste becomes extremely high, and for example, the screen printability when forming the conductive thin film is remarkably lowered, and the film thickness of the formed conductive thin film is increased. It may become thicker and the laser etching processability may decrease.

The type of silicon dioxide particles (D) used in the conductive paste of the present invention is not limited, but silica, fumed silica (for example, Aerosil manufactured by Nippon Aerosil Co., Ltd.), colloidal silica and the like can be used. When silicon dioxide particles are not used, the filler filling property in the conductive thin film is poor, the solvent bumps, and ring-shaped dents are likely to occur. On the other hand, by using silicon dioxide particles, the filler filling property in the conductive thin film is improved, so that the solvent is less likely to bump and ring-shaped dents can be suppressed.

The average primary particle diameter of the silicon dioxide particles used in the present invention is preferably 200 nm or less, more preferably 50 nm or less, and further preferably 20 μm or less. If the particle size of the silicon oxide particles is large, the filling property of the filler is poor and the ring-shaped dent cannot be suppressed.

The content of the silicon dioxide particles used in the present invention is preferably 25 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the metal powder.

As the carbon particles (E) used in the conductive paste of the present invention, Ketjen black, acetylene black, furnace black, channel black, lamp black and the like can be used. When carbon particles are not used, the filler filling property in the conductive thin film is poor, and the solvent pushes up the coating film surface layer during drying, and ring-shaped dents are likely to occur. On the other hand, by blending an appropriate amount of carbon particles, the filler filling property in the conductive thin film is improved, the solvent path is dispersed and uniformized, and the solvent path is not concentrated in one place, so that ring-shaped dents can be suppressed.

The average primary particle diameter of the carbon particles used in the present invention is preferably 200 nm or less, more preferably 50 nm or less, and even more preferably 20 μm or less. If the particle size of the silicon oxide particles is large, the filling property of the filler is poor and the ring-shaped dent cannot be suppressed.

The content of the carbon particles used in the present invention is preferably 25 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the metal powder. The carbon particles of the present invention also have an action as a laser light absorber.

The following inorganic substances can be added as the inorganic particles (H) to be blended in the conductive paste of the present invention. Inorganic substances include various carbides such as silicon carbide, boron carbide, titanium carbide, zirconium carbide, hafnium carbide, vanadium carbide, tantalum carbide, niobium carbide, tungsten carbide, chromium carbide, molybdenum carbide, calcium carbide, and diamond carbon lactam; boron nitride. , Various nitrides such as titanium nitride and zirconium nitride, various hobodies such as zirconium borohydride; various oxides such as titanium oxide (titania), calcium oxide, magnesium oxide, zinc oxide, copper oxide and aluminum oxide; calcium titanate , Various titanium acid compounds such as magnesium titanate and strontium titanate; sulfides such as molybdenum disulfide; sulfated products such as barium sulfate and magnesium sulfate; various fluorides such as magnesium fluoride and carbon fluoride; aluminum stearate, Various metal soaps such as calcium stearate, zinc stearate, magnesium stearate; in addition, talc, bentonite, talc, calcium carbonate, bentonite, kaolin, glass fiber, mica and the like can be used. By adding these inorganic substances, it may be possible to improve printability, heat resistance, mechanical properties, and long-term durability.

As the inorganic particles to be blended in the conductive paste of the present invention, an inorganic ion capturing agent can be preferably used. The inorganic ion capture agent is an inorganic particle having a primary particle diameter of submicron, and is a hydrotalcite hybridized with a metal oxide or a hydroxide. Examples of commercially available products include IXE and IXEPLAS manufactured by Toagosei Co., Ltd.

The average particle size of the inorganic particles used in the present invention is 0.1 μm or more and 3 μm or less, which is preferable. It is 1 μm or more and 1.2 μm, more preferably 0.13 μm or more and 0.85 μm or less. If the particle size of the inorganic particles is large, the filling property of the filler is poor and the ring-shaped dent cannot be suppressed.

The content of the inorganic particles used in the present invention is preferably 25 parts by mass or less, more preferably 10 parts by mass or less, based on 100 parts by mass of the metal powder.

The laser light absorber (F) may be blended in the conductive paste of the present invention. Here, the laser light absorber is an additive having strong absorption at the wavelength of the laser light, and the laser light absorber itself may be conductive or non-conductive. For example, when a YAG laser having a wavelength of the fundamental wave of 1064 nm is used as a light source, a dye and / or a pigment having a strong absorption at a wavelength of 1064 nm can be used as a laser light absorber. By blending the laser light absorber, the conductive thin film of the present invention absorbs the laser light with high efficiency, and the volatilization and thermal decomposition of the binder resin due to heat generation are promoted, and as a result, the suitability for laser etching processing is improved.

Among the laser light absorbers that can be used in the present invention, examples of those having conductivity include carbon-based fillers such as carbon black and graphite powder. There are no restrictions on the type of carbon black, such as Ketjen black, acetylene black, furnace black, channel black, and lamp black. Among these, Ketjen black is preferable from the viewpoint of conductivity and laser absorption. The formulation of a carbon-based filler also has the effect of enhancing the conductivity of the conductive thin film of the present invention. For example, since carbon black has an absorption wavelength in the vicinity of 1060 nm, it has a wavelength of 1064 nm such as a YAG laser and a fiber laser. When irradiated with laser light, the conductive thin film absorbs the laser light with high efficiency, which increases the sensitivity to laser light irradiation, which is good even when the scanning speed of laser irradiation is increased and / or when the laser light source has a low output. The effect of obtaining laser etching processing suitability can be expected. The content of the carbon-based filler is preferably 0.1 to 5 parts by weight, more preferably 0.3 to 2 parts by weight, based on 100 parts by weight of the metal powder. If the blending ratio of the carbon-based filler is too low, the effect of increasing the conductivity and the effect of increasing the sensitivity to laser light irradiation are small. On the other hand, if the blending ratio of the carbon-based filler is too high, the conductivity of the conductive thin film tends to decrease, and further, the resin is adsorbed to the void portion of the carbon, and the adhesion to the base material decreases. Points may occur.

Among the laser light absorbers that can be used in the present invention, examples of non-conductive laser light absorbers include conventionally known dyes, pigments, and infrared absorbers. More specifically, azo dyes, metal complex salt azo dyes, pyrazolone azo dyes, naphthoquinone dyes, anthraquinone dyes, phthalocyanine dyes, carbonium dyes, quinoneimine dyes, methine dyes, cyanine dyes, squarylium dyes, pyrylium salts, metal thiolate complexes and the like. Examples of dyes and pigments include black pigments, yellow pigments, orange pigments, brown pigments, red pigments, purple pigments, blue pigments, green pigments, fluorescent pigments, metal powder pigments, and other polymer-bound pigments. Specifically, insoluble azo pigments, azolake pigments, condensed azo pigments, chelate azo pigments, phthalocyanine pigments, anthraquinone pigments, perylene and perinone pigments, thioindigo pigments, quinacridone pigments, dioxazine pigments, isoindolinone pigments. , Kinoftalone pigments, dyed lake pigments, azine pigments, nitroso pigments, nitro pigments, natural pigments, fluorescent pigments, and inorganic pigments can be used. Examples of the infrared absorber include NIR-IM1 which is a diimonium salt type infrared absorber and NIR-AM1 which is an aminium salt type (both manufactured by Nagase ChemteX Corporation). These non-conductive laser light absorbers are preferably contained in an amount of 0.01 to 5 parts by weight, preferably 0.1 to 2 parts by weight. If the blending ratio of the non-conductive laser light absorber is too low, the effect of increasing the sensitivity to laser light irradiation is small. If the blending ratio of the non-conductive laser light absorber is too high, the conductivity of the conductive thin film may decrease, and the color of the laser light absorber becomes remarkable, which may not be preferable depending on the application.

Further, the conductive paste of the present invention includes a thixo-imparting agent, a defoaming agent, a flame retardant, a tackifier, a hydrolysis inhibitor, a leveling agent, a plasticizer, an antioxidant, an ultraviolet absorber, a flame retardant, and a pigment. , Dyes can be blended. Further, carbodiimide, epoxy and the like can be appropriately blended as a resin decomposition inhibitor. These can be used alone or in combination.

The conductive paste of the present invention may contain a curing agent (G) capable of reacting with the binder resin to the extent that the effect of the present invention is not impaired. By blending a curing agent, the curing temperature may increase and the load on the production process may increase, but it is expected that the moisture resistance of the coating film will be improved by cross-linking due to the heat generated during the drying of the coating film or laser etching. ..

The curing agent capable of reacting with the binder resin of the present invention is not limited in type, but an isocyanate compound and / or an epoxy resin is particularly preferable from the viewpoint of adhesion, bending resistance, curability and the like. Further, as for the isocyanate compound, it is preferable to use a compound in which an isocyanate group is blocked because the storage stability is improved. Examples of the curing agent other than the isocyanate compound include amino resins such as methylated melamine, butylated melamine, benzoguanamine and urea resin, and known compounds such as acid anhydrides, imidazoles and phenol resins. A known catalyst or accelerator selected according to the type can be used in combination with these curing agents. The amount of the curing agent to be blended is such that the effect of the present invention is not impaired and is not particularly limited, but 0.5 to 50 parts by mass with respect to 100 parts by mass of the binder resin. Preferably, 1 to 30 parts by mass is more preferable, and 2 to 20 parts by mass is further preferable.

Examples of the isocyanate compound that can be blended in the conductive paste of the present invention include aromatic or aliphatic diisocyanates, trivalent or higher polyisocyanates, and may be either low molecular weight compounds or high molecular weight compounds. For example, aliphatic diisocyanates such as tetramethylene diisocyanate and hexamethylene diisocyanate, aromatic diisocyanates such as toluene diisocyanate, diphenylmethane diisocyanate and xylylene diisocyanate, hydride diphenylmethane diisocyanate, hydride xylylene diisocyanate, dimerate diisocyanate, isophorone diisocyanate and the like. Alicyclic diisocyanates, or trimerics of these isocyanate compounds, and excess amounts of these isocyanate compounds and, for example, ethylene glycol, propylene glycol, trimethylolpropane, glycerin, sorbitol, ethylenediamine, monoethanolamine, diethanolamine, triethanolamine. Examples thereof include terminal isocyanate group-containing compounds obtained by reacting with low-molecular-weight active hydrogen compounds such as, various polyester polyols, polyether polyols, and high-molecular-weight active hydrogen compounds of polyamides. Examples of the isocyanate group blocking agent include phenols such as phenol, thiophenol, methylthiophenol, ethylthiophenol, cresol, xylenol, resorcinol, nitrophenol, and chlorophenol; oximes such as acetoxime, methylethylketooxime, and cyclohexanone oxime. Classes; alcohols such as methanol, ethanol, propanol and butanol; halogen-substituted alcohols such as ethylene chlorhydrin and 1,3-dichloro-2-propanol; tertiary alcohols such as t-butanol and t-pentanol. Ε-caprolactam, δ-valerolactam, γ-butyrolactam, β-propyrolactam and other lactams, pyrazole blocking agents, and other aromatic amines, imides, acetylacetones, acetacetic esters, malons. Examples thereof include active methylene compounds such as acid ethyl esters, mercaptans, imines, imidazoles, ureas, diaryl compounds, sodium bicarbonate and the like. Of these, oximes, imidazoles, amines, and pyrazoles are particularly preferable from the curability.

Epoxy compounds used as a curing agent in the present invention include, for example, glycidyl ether types such as bisphenol A glycidyl ether, bisphenol S glycidyl ether, novolak glycidyl ether, brominated bis, hexahydrophthalic acid glycidyl ester, dimer acid glycidyl ester and the like. Examples include glycidyl ester type, triglycidyl isocyanurate, or alicyclic or aliphatic epoxiside such as 3,4? Epoxycyclohexylmethylcarboxylate, epoxidized polybutadiene, and epoxidized soybean oil. The above may be used together. Of these, bisphenol A glycidyl ether is most preferable from the viewpoint of curability, and among them, those having a molecular weight of less than 5000 and having two or more glycidyl ether groups in one molecule are more preferable.

The viscosity of the conductive paste of the present invention is not particularly limited and may be appropriately adjusted according to the method for forming the coating film. For example, when the conductive paste is applied to the substrate by screen printing, the viscosity of the conductive paste is preferably 200 dPa · s or more when measured at the printing temperature with a BH type viscometer 20 rpm, and further. It is preferably 400 dPa · s or more, and most preferably 600 dPa · s or more. The upper limit is not particularly limited, but if the viscosity is too high, the film thickness of the conductive thin film becomes too thick, and the laser etching process suitability may decrease.

The conductive paste of the present invention preferably has an F value of 60 to 95%, more preferably 75 to 95%. The F value is a numerical value indicating a filler mass part with respect to 100 parts by mass of the total solid content contained in the paste, and is represented by F value = (filler mass part / solid content mass part) × 100. The filler mass portion referred to here is a mass portion of the conductive powder, and the solid content mass portion is a mass portion of a component other than the solvent, and includes all the conductive powder, the binder resin, and other curing agents and additives. If the F value is too low, a conductive thin film showing good conductivity cannot be obtained, and if the F value is too high, the adhesion between the conductive thin film and the substrate and / or the surface hardness of the conductive thin film tends to decrease. Therefore, deterioration of printability is inevitable. Here, the conductive powder refers to both a metallic powder and a non-metal conductive powder.

The conductive thin film of the present invention is formed by applying or printing the conductive paste of the present invention on a substrate to form a coating film, and then volatilizing the organic solvent contained in the coating film to dry the coating film. be able to. The method of applying or printing the conductive paste on the substrate is not particularly limited, but printing by the screen printing method is a technique widely used in the industry for forming an electric circuit using the conductive paste and the simplicity of the process. It is preferable from the viewpoint of. Further, the conductive paste can be applied or printed on a portion slightly wider than the conductive thin film portion finally required as an electric circuit to reduce the load of the laser etching process and efficiently obtain the electric circuit of the present invention. It is preferable from the viewpoint of forming.

As the base material to which the conductive paste of the present invention is applied, a material having excellent dimensional stability is preferably used. For example, a film made of a material having excellent flexibility such as polyethylene terephthalate, polyethylene naphthalate, polybutylene terephthalate, or polycarbonate can be mentioned. Further, an inorganic material such as glass can also be used as a base material. The thickness of the base material is not particularly limited, but is preferably 12.5 μm to 1 mm, more preferably 25 μm to 0.5 mm. Considering the mechanical properties, shape stability, handleability, etc. of the pattern forming material, it is within the above range.

Further, by physically and / or chemically treating the surface of the base material to which the conductive paste of the present invention is applied, the adhesion between the conductive thin film and the base material can be improved. Examples of the physical treatment method include a sandblast method, a wet blast method for injecting a liquid containing fine particles, a corona discharge treatment method, a plasma treatment method, an ultraviolet ray or a vacuum ultraviolet irradiation treatment method, and the like. Further, as an example of the chemical treatment method, a strong acid treatment method, a strong alkali treatment method, an oxidizing agent treatment method, a coupling agent treatment method and the like can be mentioned.

Further, the base material may have a transparent conductive layer. The conductive thin film of the present invention can be laminated on the transparent conductive layer. The material of the transparent conductive layer is not particularly limited, and examples thereof include an ITO film containing indium tin oxide as a main component and a silver nanowire film made of nano-sized linear silver. Further, as the transparent conductive layer, not only the one formed on the entire surface of the base material but also the one in which a part of the transparent conductive layer is removed by etching or the like can be used.

The step of volatilizing the organic solvent is preferably performed at room temperature and / or under heating. In the case of heating, the heating temperature is preferably 80 ° C. or higher, more preferably 100 ° C. or higher, still more preferably 110 ° C. or higher, because the conductivity, adhesion and surface hardness of the dried conductive thin film are good. Further, from the viewpoint of heat resistance of the transparent conductive layer of the base and energy saving in the production process, the heating temperature is preferably 150 ° C. or lower, more preferably 135 ° C. or lower, still more preferably 130 ° C. or lower. When the curing agent is blended in the conductive paste of the present invention, the curing reaction proceeds when the step of volatilizing the organic solvent is performed under heating.

The thickness of the conductive thin film of the present invention may be set to an appropriate thickness according to the intended use. However, from the viewpoint of good conductivity of the conductive thin film after drying and good laser etching processing suitability, the film thickness of the conductive thin film is preferably 3 μm or more, 30 μm or less, and more preferably 4 μm. The above is 20 μm or less, more preferably 4 μm or more and 10 μm or less. If the film thickness of the conductive thin film is too thin, the desired conductivity as a circuit may not be obtained. If the film thickness is too thick, the amount of laser irradiation required for the laser etching process becomes excessive, which may damage the substrate. Further, if the film thickness varies widely, the ease of etching of the conductive thin film varies, and short circuits between lines due to insufficient etching and disconnection due to excessive etching tend to occur easily. Therefore, it is better that the variation in film thickness is small.

The surface roughness Ra of the conductive thin film of the present invention is preferably 0.7 μm or less, more preferably 0.5 μm or less, still more preferably 0.4 μm or less. If the surface roughness Ra is too high, knurling is likely to occur at the etching end of the conductive thin film, and there is a possibility that short circuits between the lines and disconnection due to excessive etching are likely to occur. Since the surface roughness Ra is strongly affected by the paste composition (particularly the binder type and the silver powder type), the paste viscosity, and the screen printing conditions, it is necessary to appropriately adjust and control these.

In the electric circuit of the present invention, at least a part of the conductive thin film formed on the substrate by the conductive paste of the present invention is irradiated with laser light, and a part of the conductive thin film is removed from the substrate. It is an electric circuit having a wiring portion formed by the above. If such an electric circuit forming method is adopted, unlike the photolithography method, the pattern forming process can be a dry process, and no waste liquid containing a metal component is generated, so that waste liquid treatment is not required and it is environmentally friendly. It can be said that it is a process. In addition, since the process is simple, investment in manufacturing equipment can be suppressed, and maintenance after operation of manufacturing equipment is easy. The method of forming the conductive thin film on the substrate by the conductive paste is not particularly limited, but it can be performed by printing or painting.

The method of irradiating the laser beam is not particularly limited, but a laser etching processing device that has become widespread in recent years or a device with further improved dimensional accuracy can be used. Since the laser etching processing apparatus can use the data produced by image processing application software such as CAD as it is for laser processing, it is extremely easy to switch the manufacturing pattern. This can be mentioned as one of the advantages over the pattern formation in the conventional screen printing method.

In the portion where the laser beam is irradiated and absorbed, the energy of the laser beam is converted into heat, and thermal decomposition and / or volatilization occurs due to the temperature rise, and the irradiated portion is peeled off and removed. In order to efficiently remove the portion of the conductive thin film of the present invention irradiated with the laser beam from the substrate, it is preferable that the conductive thin film of the present invention has strong absorption at the wavelength of the irradiation laser beam. Therefore, as the laser type, it is preferable to select a laser type having energy in a wavelength region in which any component constituting the conductive thin film of the present invention has strong absorption.

Examples of the laser type include an excima laser (wavelength of the fundamental wave is 193 to 308 nm), a YAG laser (wavelength of the fundamental wave is 1064 nm), a fiber laser (wavelength of the fundamental wave is 1060 nm), and a semiconductor laser. Basically, there is no problem with any method and wavelength of laser type. By selecting a laser type that matches the absorption wavelength region of any of the components of the conductive thin film and can irradiate a wavelength at which the substrate does not have strong absorption, the conductive thin film at the laser beam irradiation site is selected. Can be efficiently removed and damage to the base material can be avoided. From this point of view, the wavelength of the laser to be irradiated is preferably 190 nm to 1100 nm, more preferably 500 nm to 1000 nm. When a conductive thin film having polyester in the layer structure or a thin film in which a part of the conductive thin film having polyester in the layer structure is removed by etching is used as the base material, it is possible to use a YAG laser or a fiber laser. Since the base material does not absorb the wavelength of the fundamental wave, it is particularly preferable in that it does not easily damage the base material.

The laser output and frequency are not particularly limited, but the conductive thin film at the laser beam irradiation site can be removed with an etching width of 10 to 40 μm, and the underlying substrate is adjusted so as not to be damaged. In general, it is preferable to appropriately adjust the laser output in the range of 0.5 to 100 W, a frequency of 10 to 1000 kHz, and a pulse width of 1000 ns or less. If the laser output is too low, the removal of the conductive thin film tends to be insufficient, but such a tendency can be avoided to some extent by reducing the scanning speed of the laser or increasing the number of scannings. If the laser output is too high, the portion where the conductive thin film is peeled off due to the diffusion of heat from the irradiated portion becomes extremely larger than the laser beam diameter, and the line width may become too narrow or the wire may be broken. In this respect, the laser output is preferably adjusted appropriately in the range of 0.5 to 20 W, frequency 10 to 800 kHz, and pulse width 800 ns or less, more preferably 0.5 to 12 W, frequency 10 to 600 kHz, and pulse width 600 ns. It is as follows. The lower limit of the pulse width is preferably 1 fs or more, more preferably 1 ps or more, and most preferably 1 ns or more.

The higher the scanning speed of the laser beam is, the better from the viewpoint of improving the production efficiency by reducing the tact time. Specifically, 1000 mm / s or more is preferable, 1500 mm / s or more is more preferable, and 2000 mm / s or more is more preferable. ,. The upper limit is not particularly limited, but is approximately 10,000 mm / s or less. If the scanning speed is too slow, not only the production efficiency is lowered, but also the conductive thin film and the substrate may be damaged by the thermal history. The upper limit of the processing speed is not particularly set, but if the scanning speed is too high, the removal of the conductive thin film at the laser beam irradiation site may be incomplete and the circuit may be short-circuited. Further, if the scanning speed is too fast, it is unavoidable to reduce the scanning speed at the corner portion of the formed pattern as compared with the straight portion, so that the thermal history of the corner portion becomes higher than that of the straight portion, and the corner Laser etching of the part The physical properties of the conductive thin film around the part may be significantly deteriorated.

The scanning of the laser beam may be performed by moving the projectile of the laser beam, moving the irradiated object irradiated with the laser beam, or a combination of both, and can be realized by using, for example, an XY stage. It is also possible to scan the laser beam by changing the irradiation direction of the laser beam using a galvano mirror or the like.

By using a condenser lens (achromatic lens or the like) when irradiating the laser beam, the energy density per unit area can be increased. The advantage of this method is that the energy density per unit area can be increased compared to the case of using a mask, so even a laser oscillator with a small output can perform laser etching at a high scanning speed. Is possible. When irradiating a conductive thin film with focused laser light, it is necessary to adjust the focal length. The focal length needs to be adjusted especially by the film thickness applied to the substrate, but it can be adjusted so as not to damage the substrate and to peel off / remove a predetermined conductive thin film pattern. preferable.

It is one of the preferred embodiments that the scanning of the laser beam is repeated a plurality of times in the same pattern. Even if there is a conductive thin film part that is incompletely removed in the first scan, or if the components that make up the removed conductive thin film adhere to the substrate again, the laser light irradiation part is detected in multiple scans. It is possible to completely remove the conductive thin film of. The number of scans is preferably 4 times, more preferably 3 times. The upper limit is not particularly limited, but care must be taken because the area around the processed portion may be damaged, discolored, and the physical characteristics of the coating film deteriorate due to the heat history received multiple times. Further, from the viewpoint of production efficiency, it is natural that the smaller the number of scans is, the better.

It is also one of the preferred embodiments that the scanning of the laser beam is not repeated a plurality of times in the same pattern. As long as the characteristics of the obtained conductive thin film, conductive laminate and electric circuit are not adversely affected, it is natural that the smaller the number of scans, the better the production efficiency.

Since the conductive thin film of the present invention contains an expensive conductive powder in a high concentration, it is included in the conductive thin film removed from the base material in consideration of the total cost required for manufacturing the electric circuit to be manufactured. It is important to collect and reuse the conductive powder. By installing a high-performance dust collector near the laser beam irradiation site and constructing a system that efficiently recovers the conductive powder, it is possible to make the processing method sufficiently profitable.

The conductive thin film, the conductive laminate and / or the electric circuit of the present invention can be used as a component of a touch panel. The touch panel may be of a resistance film type or a capacitance type. Although it can be applied to any touch panel, since this paste is suitable for forming fine wires, it can be particularly preferably used for electrode wiring of a capacitive touch panel. As the base material constituting the touch panel, a film or glass base material having a transparent conductive layer such as an ITO film or a silver nanowire film, or a base material from which they are partially removed by etching is used. Is preferable.

Examples and comparative examples are given below to explain the present invention in more detail, but the present invention is not limited to the examples. The measured values described in Examples and Comparative Examples were measured by the following methods.

1. 1. The number average molecular weight sample binder resin was dissolved in tetrahydrofuran so that the resin concentration was about 0.5% by weight, and filtered through a polytetrafluoroethylene membrane filter having a pore size of 0.5 μm to prepare a GPC measurement sample. GPC measurement of a resin sample at a column temperature of 30 ° C. and a flow rate of 1 ml / min using a gel permeation chromatograph (GPC) Prominence manufactured by Shimadzu Corporation as a mobile phase and a differential refractometer (RI meter) as a detector. Was done. The number average molecular weight was calculated by using a standard polystyrene conversion value and omitting a portion corresponding to a molecular weight of less than 1000. As the GPC column, shodex KF-802, 804L, 806L manufactured by Showa Denko KK was used.

2. 2. Glass transition temperature (Tg)
Place 5 mg of the sample binder resin in an aluminum sample pan, seal it, and use a differential scanning calorimetry (DSC) DSC-220 manufactured by Seiko 25 Instruments Co., Ltd. to a temperature rise rate of 20 ° C / min up to 200 ° C. It was determined by the temperature of the intersection of the extension line of the baseline below the glass transition temperature and the tangent line showing the maximum inclination at the transition part.

3. 3. 0.2 g of the acid value sample binder resin was precisely weighed and dissolved in 20 ml of chloroform. Then, a phenolphthalein solution was used as an indicator, and titration was performed with 0.01 N potassium hydroxide (ethanol solution). The unit of acid value was eq / ton, that is, equivalent per ton of sample. Note that tons here are metric tons.

4. Resin composition The sample binder resin was dissolved in chloroform-d, and the resin composition was determined by 1H-NMR analysis using a 400 MHz-NMR device manufactured by VARIAN.

5. Preparation of Conductive Laminated Test Piece A 400 mesh stainless steel screen was used for each of the 100 μm thick annealed PET film (Toray Industries, Inc. Lumirror S) and ITO film (Oike Kogyo Co., Ltd., KH150). A conductive paste was printed by a screen printing method to form a solid coating pattern with a width of 25 mm and a length of 450 mm, and then heated in a hot air circulation type drying oven at 130 ° C. for 30 minutes to obtain a conductive laminate test piece. .. The coating thickness at the time of printing was adjusted so that the dry film thickness was 4 to 10 μm.

6. Adhesion The conductive laminate test piece was evaluated by a peeling test using cellophane tape (registered trademark) (manufactured by Nichiban Co., Ltd.) according to JIS K-5400-5-6: 1990. However, the number of cuts in each direction of the grid pattern was 11, and the cut interval was 1 mm. 100/100 indicates that there is no peeling and the adhesion is good, and 0/100 indicates that all have peeled off.

7. Specific resistance The sheet resistance and film thickness of the conductive laminate test piece were measured, and the specific resistance was calculated. As the film thickness, a gauge stand ST-022 (manufactured by Ono Sokki Co., Ltd.) was used, the thickness of the cured coating film was measured at 5 points with the thickness of the PET film as the zero point, and the average value was used. The sheet resistance was measured for four test pieces using MILLIOHMMETER4338B (manufactured by Hewlett-Packard), and the average value thereof was used. The range that can be detected by this milliohm meter is 1 × 10-2 (Ω · cm) or less, and the specific resistance of 1 × 10-2 (Ω · cm) or more is out of the measurement limit.

8. Moisture resistance test:
The conductive laminate test piece was heated at 80 ° C. for 300 hours, then heated at 85 ° C. and 85% RH (relative humidity) for 300 hours, and then left at room temperature for 24 hours, and then various evaluations were performed.

9. Surface Roughness In the conductive laminate test piece 1, the surface roughness Ra was measured using a surface roughness meter (Handy Surf E-35B, manufactured by Tokyo Seimitsu Co., Ltd., calculated based on JIS-1994).

10. Evaluation of Laser Etching Appropriateness A conductive paste was printed in a rectangle of 2.5 × 10 cm on a polyester substrate (Toray Industries, Inc. Lumirror S (thickness 100 μm)) by a screen printing method. The screen plate is 400 mesh, the wire diameter is 18 μm, the emulsion is processed, the emulsion thickness is 10 μ, and the printing machine is SSA-TF150E manufactured by Tokai Shoji Co., Ltd. The printing conditions are clearance speed 100 mm / s, scraper speed 75 mm / s, pushing. Amount 1.0 mm / s, clearance 1.5 mm, squeegee pressure 0.4 MPa, squeegee angle 75 degrees, squeegee hardness 80 degrees. After printing, it was dried at 130 ° C. for 30 minutes in a hot air circulation type drying oven to obtain a conductive thin film. The paste was diluted and adjusted so that the film thickness was 5 to 7 μm. Next, the conductive thin film prepared by the above method was laser-etched to prepare 10 patterns having four linear portions having a length of 50 mm as shown in FIG. 2, and used as a laser etching aptitude evaluation test piece. .. The laser etching process was performed by scanning the laser beam three times at a pitch of 40 μm (L / S = 20/20 μm). The conditions were that a fiber laser (wavelength: 1064 nm) was used as the laser light source, the frequency was 300 kHz, the scanning speed was 2500 mm / s, the pulse width was 15 ns, and the output was appropriately adjusted, and the laser etching process was performed.

11. Laser etching aptitude evaluation (1) Conductivity between both ends of the thin wire The laser etching aptitude evaluation test piece was evaluated based on whether the continuity between both ends of the thin wire was secured. Specifically, a tester is applied to each of the terminals 1a-terminal 1c, the terminal 2a-terminal 2c, the terminal 3a-terminal 3c, and the terminal 4a-terminal 4c to check the presence or absence of continuity, and the following evaluation criteria are used. Judgment. Since 10 test pieces were prepared and 4 pieces were prepared for each piece, evaluation was performed using 40 thin lines.
◯; There is continuity between both ends of the thin wire for all 40 thin wires Δ; Of the 40 thin wires, less than 10 have no continuity between both ends of the thin wire.
X; Of the 40 thin wires, 10 or more have no continuity between both ends of the thin wires.

12. Laser etching aptitude evaluation (2) Insulation between adjacent thin wires In the laser etching aptitude evaluation test piece, evaluation was made based on whether insulation between adjacent fine wires was secured. Specifically, the presence or absence of continuity was confirmed by applying a tester to each of the terminals 1a-terminal 2a, the terminal 2a-terminal 3a, and the terminal 3a-terminal 4a, and the determination was made according to the following evaluation criteria. Ten test pieces were prepared, and there were three levels per piece, and evaluation was carried out at a total of 30 levels.
◯; Insulation between adjacent thin wires of all 30 levels Δ; Insulation between adjacent thin wires of 20 levels or more ×; Insulation between adjacent thin wires of less than 20 levels

13. Evaluation of ring-shaped dents A conductive paste was printed in a rectangular shape of 0.5 × 80 mm on a polyester substrate (Toray Industries, Inc. Lumirror S (thickness 100 μm)) by a screen printing method. The screen plate is 400 mesh, the wire diameter is 18 μm, the emulsion is processed, the emulsion thickness is 10 μ, and the printing machine is SSA-TF150E manufactured by Tokai Shoji Co., Ltd. The printing conditions are clearance speed 100 mm / s, scraper speed 75 mm / s, pushing. Amount 1.0 mm / s, clearance 1.5 mm, squeegee pressure 0.4 MPa, squeegee angle 75 degrees, squeegee hardness 80 degrees. After printing, it was dried at 130 ° C. for 30 minutes in a hot air circulation type drying oven to obtain a conductive thin film. In the obtained conductive thin film, the number of ring-shaped dents was measured using a laser microscope (KEYENCE VHX-1000), and the determination was made according to the following evaluation criteria.
Number of ring-shaped dents (pieces / cm2)
◎ 0-5
○ 6-20
△ 21-50
× 51 or more

<Examples 1 to 3, Comparative Example 1>
Four types of conductive pastes were prepared according to the compounding ratios shown in Table 1. First, the binder resin is dissolved in an appropriate amount of solvent so that the solid content concentration becomes 35% by mass, and the obtained binder resin solution, silver powder 1, curing agent, curing catalyst, remaining solvent amount, and other additives are weighed and mixed. After premixing, the mixture was passed through a chilled three-roll kneader twice and dispersed. Next, a 795 mesh (stainless steel mesh filter (wire diameter 16 μm, opening 16 μm) filtration filter was attached to a paste filter (PF320A manufactured by Protech), and the paste was filtered.
Then, the obtained conductive paste was printed on a predetermined pattern so that the dry film thickness was 17 μm, and then dried at 120 ° C. for 30 minutes to obtain a conductive thin film. The basic physical properties were measured using the obtained conductive thin film, and then the laser etching process was examined. The evaluation results are shown in Table 1.

Table 1

In addition, Table 1,
Silver powder 1: Aggregated silver powder (D50: 1.3 μm)
Silver powder 2: Flaky silver powder (D50: 1.3 μm)
Silver powder 3: Spherical silver powder (D50: 1.3 μm)
Binder resin 1: PKHC manufactured by InChem (phenoxy resin, number average molecular weight 21000, Tg = 89 ° C)
Binder resin 2: PKHC modified product manufactured by InChme (phenoxy resin, number average molecular weight 21000, Tg = 97 ° C.)
Binder resin 3: Toyobo Byron 103 (Tg = 47 ° C., acid value 25)
Silica 1: AEROSIL 300 manufactured by Nippon Aloesil (primary particle size: 7 nm)
Carbon 1: Lion ECP600JD (primary particle size: 34 nm)
Inorganic filler 1: Toagosei ion supplement IXE-PLAS A2 (median diameter: 0.2 μm)
Solvent 1: Ethylene glycol monobutyl ether acetate
Solvent 2: Diethylene glycol monoethyl ether acetate
Solvent 3: Diethylene glycol monobutyl ether acetate
Hardener 1: Baxenden blocked isocyanate BI7960
Hardener 1: Baxenden blocked isocyanate BI7982
Curing catalyst: KS1260 manufactured by Kyodo Yakuhin Co., Ltd.
Dispersant 1: Disperbyk 167 manufactured by Big Chemie Japan Co., Ltd.
Additive 1: Carboxylic acid amine salt Additive 2: Carboxylic acid.

<Application example 1>
Using the obtained conductive paste P1, printing was performed so that the drying film thickness was 17 μm, and the drying temperature and the drying time were changed to evaluate the ring-shaped dent defect, the conductivity at both ends of the thin wire, and the insulation at both ends of the thin wire. The results are shown in Tables 2 to 4. It has been shown that when the product is dried at a low temperature for a long time, the dents in the ring are reduced, and the conductivity at both ends of the thin wire and the insulation at both ends of the thin wire tend to be improved.

Table 2

Table 3

Table 4

<Application example 2>
Using the obtained conductive pastes P2 to P4, printing was performed so that the drying film thickness was 17 μm, and the drying temperature and drying time were changed to obtain ring-shaped dent defects, fine wire both ends conductivity, and thin wire both ends insulation. evaluated. The results are shown in Tables 5-7.

Table 5

Table 6

＜応用例３＞
得られた導電ペ-ストＰ１～Ｐ４を用い、各々乾燥条件を変えてリング状凹み欠点が少なくなる条件を見つけ、細線両端間導通性、細線両端間絶縁性を評価した。結果を表８．に示す。Table 7

<Application example 3>
Using the obtained conductive pastes P1 to P4, the conditions for reducing the ring-shaped dent defects were found by changing the drying conditions, and the conductivity between both ends of the thin wire and the insulation between both ends of the thin wire were evaluated. The results are shown in Table 8. Shown in.

Table 8

<Example 11>
The conductive paste was adjusted according to the compounding ratio shown in Table 11. First, the binder resin is dissolved in an appropriate amount of solvent so that the solid content concentration becomes 35% by mass, and the obtained binder resin solution, silver powder 1, curing agent, curing catalyst, remaining solvent amount, and other additives are weighed and mixed. After premixing, the mixture was passed through a chilled three-roll kneader twice and dispersed. Next, a filter of 795 mesh (stainless steel mesh filter (line diameter 16 μm, opening 16 μm)) was attached to a paste filter (PF320A manufactured by Protech), and the above paste was filtered. Then, the obtained conductive paste was obtained. Was printed on a predetermined pattern and dried at 130 ° C. for 30 minutes to obtain a conductive thin film. Basic physical properties were measured using this conductive thin film, and then laser etching processing was examined. , Shown in Table 11.

<Examples 12 to 21, Comparative Examples 11 to 13>
Examples 12 to 21 and Comparative Examples 11 to 13 were carried out by changing the resin and the composition of the conductive paste. Table 11 shows the formulation and evaluation results of the conductive paste. In the examples, good coating film physical characteristics could be obtained by heating in an oven at a relatively low temperature of 130 ° C. × 30 minutes for a short time. In addition, the adhesion to the ITO film and the evaluation after the moist heat environment test were also good.

Table 11

In Table 11,
Silver powder 1: Aggregated silver powder (D50: 1.3 μm)
Silver powder 2: Flaky silver powder (D50: 1.3 μm)
Silver powder 3: Spherical silver powder (D50: 1.3 μm)
Binder resin 1: PKHC manufactured by InChem (phenoxy resin, number average molecular weight 21000, Tg = 89 ° C)
Binder resin 2: PKHC modified product manufactured by InChme (phenoxy resin, number average molecular weight 21000, Tg = 97 ° C.)
Binder resin 3: Toyobo Byron 600 (Tg = 45 ° C., acid value 30)
Binder resin 4: Toyobo Byron 103 (Tg = 47 ° C., acid value 25)
Binder resin 5: Toyobo Byron 270 (Tg = 67 ° C., acid value 30)
Silica 1: AEROSIL 300 manufactured by Nippon Aloesil (primary particle size: 7 nm)
Silica 2: AEROSIL 130 manufactured by Nippon Aloesil (primary particle size: 16 nm)
Silica 3: Made by Nippon Aloesil AEROSIL R972 (primary particle size: 16 nm)
Solvent 1: Ethylene glycol monobutyl ether acetate Solvent 2: Diethylene glycol monoethyl ether acetate Solvent 3: Diethylene glycol monobutyl ether acetate Hardener 1: Baxenden blocked isocyanate BI7960
Hardener 1: Baxenden blocked isocyanate BI7982
Curing catalyst: KS1260 manufactured by Kyodo Yakuhin Co., Ltd.
Dispersant 1: Disperbyk 167 manufactured by Big Chemie Japan Co., Ltd.
Additive 1: Carboxylic acid amine salt Additive 2: Carboxylic acid.

<Example 31>
The conductive paste was adjusted according to the compounding ratio shown in Table 12. First, the binder resin is dissolved in an appropriate amount of solvent so that the solid content concentration becomes 35% by mass, and the obtained binder resin solution, silver powder 1, curing agent, curing catalyst, remaining solvent amount, and other additives are weighed and mixed. After premixing, the mixture was passed through a chilled three-roll kneader twice and dispersed. Next, a filter of 795 mesh (stainless steel mesh filter (line diameter 16 μm, opening 16 μm)) was attached to a paste filter (PF320A manufactured by Protech), and the above paste was filtered. Then, the obtained conductive paste was obtained. Was printed on a predetermined pattern and dried at 130 ° C. for 30 minutes to obtain a conductive thin film. Basic physical properties were measured using this conductive thin film, and then laser etching processing was examined. , Shown in Table 12.

<Examples 32 to 39, Comparative Examples 1 to 3>
Examples 32 to 39 and Comparative Examples 31 to 33 were carried out by changing the resin and the composition of the conductive paste. Table 12 shows the formulation and evaluation results of the conductive paste. In the examples, good coating film physical characteristics could be obtained by heating in an oven at a relatively low temperature of 130 ° C. × 30 minutes for a short time. In addition, the adhesion to the ITO film and the evaluation after the moist heat environment test were also good.

Table 12

In Table 12,
Silver powder 1: Aggregated silver powder (D50: 1.3 μm)
Silver powder 2: Flaky silver powder (D50: 1.3 μm)
Silver powder 3: Spherical silver powder (D50: 1.3 μm)
Binder resin 1: PKHC manufactured by InChem (phenoxy resin, number average molecular weight 21000, Tg = 89 ° C)
Binder resin 2: PKHC modified product manufactured by InChme (phenoxy resin, number average molecular weight 21000, Tg = 97 ° C.)
Binder resin 3: Toyobo Byron 600 (Tg = 45 ° C., acid value 30)
Binder resin 4: Toyobo Byron 103 (Tg = 47 ° C., acid value 25)
Binder resin 5: Toyobo Byron 270 (Tg = 67 ° C., acid value 30)
Carbon 1: Lion ECP600JD (primary particle size: 34 nm)
Carbon 2: Lion carbon ECP (primary particle size: 39.5 nm)
Carbon 3: Tokai Carbon Talker Black # 5500 (Arithmetic Mean Particle Diameter: 25nm)
Carbon 4: Tokai Carbon Toe or Black # 4400 (Arithmetic Mean Particle Diameter: 38nm)
Solvent 1: Ethylene glycol monobutyl ether acetate Solvent 2: Diethylene glycol monoethyl ether acetate Solvent 3: Diethylene glycol monobutyl ether acetate Hardener 1: Baxenden blocked isocyanate BI7960
Hardener 1: Baxenden blocked isocyanate BI7982
Curing catalyst: KS1260 manufactured by Kyodo Yakuhin Co., Ltd.
Dispersant 1: Disperbyk 167 manufactured by Big Chemie Japan Co., Ltd.
Additive 1: Carboxylic acid amine salt Additive 2: Carboxylic acid.

<Example 41>
The conductive paste was adjusted according to the blending ratios shown in Tables 13 and 14. First, the binder resin is dissolved in an appropriate amount of solvent so that the solid content concentration becomes 35% by mass, and the obtained binder resin solution, silver powder 1, curing agent, curing catalyst, remaining solvent amount, and other additives are weighed and mixed. After premixing, the mixture was passed through a chilled three-roll kneader twice and dispersed. Next, a filter of 795 mesh (stainless steel mesh filter (line diameter 16 μm, opening 16 μm)) was attached to a paste filter (PF320A manufactured by Protech), and the above paste was filtered. Then, the obtained conductive paste was obtained. Was printed on a predetermined pattern and dried at 130 ° C. for 30 minutes to obtain a conductive thin film. Basic physical properties were measured using this conductive thin film, and then laser etching processing was examined. , Table 13 and Table 14.

<Examples 42 to 57, Comparative Examples 41 to 43>
Examples 42 to 57 and Comparative Examples 41 to 43 were carried out by changing the resin and the composition of the conductive paste. The formulation and evaluation results of the conductive paste are shown in Tables 13 and 14. In the examples, good coating film physical characteristics could be obtained by heating in an oven at a relatively low temperature of 130 ° C. × 30 minutes for a short time. In addition, the adhesion to the ITO film and the evaluation after the moist heat environment test were also good.

Table 13

Table 14

In Tables 13 and 14,
Silver powder 1: Aggregated silver powder (D50: 1.3 μm)
Silver powder 2: Flaky silver powder (D50: 1.3 μm)
Silver powder 3: Spherical silver powder (D50: 1.3 μm)
Binder resin 1: PKHC manufactured by InChem (phenoxy resin, number average molecular weight 21000, Tg = 89 ° C)
Binder resin 2: PKHC modified product manufactured by InChme (phenoxy resin, number average molecular weight 21000, Tg = 97 ° C.)
Binder resin 3: Toyobo Byron 600 (Tg = 45 ° C., acid value 30)
Binder resin 4: Toyobo Byron 103 (Tg = 47 ° C., acid value 25)
Binder resin 5: Toyobo Byron 270 (Tg = 67 ° C., acid value 30)
Silica 1: AEROSIL 300 manufactured by Nippon Aloesil (primary particle size: 7 nm)
Silica 2: AEROSIL 130 manufactured by Nippon Aloesil (primary particle size: 16 nm)
Silica 3: Made by Nippon Aloesil AEROSIL R972 (primary particle size: 16 nm)
Carbon 1: Lion ECP600JD (primary particle size: 34 nm)
Carbon 2: Lion carbon ECP (primary particle size: 39.5 nm)
Inorganic filler 1: Toagosei ion supplement IXE-700F (Median diameter: 1.5 μm)
Inorganic filler 2: Toagosei ion supplement IXE-100 (Median diameter: 1.0 μm)
Inorganic filler 3: Toagosei ion supplement IXE-PLAS A1 (Median diameter: 0.5 μm)
Inorganic filler 4: Toagosei ion supplement IXE-PLAS A2 (Median diameter: 0.2 μm)
Inorganic filler 5: Toagosei ion supplement IXE-PLAS B1 (Median diameter: 0.4 μm)
Inorganic filler 6: Titanium oxide CR-57 manufactured by Ishihara Sangyo (average particle size: 0.25 μm)
Inorganic filler 7: Titanium oxide A-100 manufactured by Ishihara Sangyo (average particle size: 0.15 μm)
Inorganic filler 8: Barium sulfate B-1 manufactured by Sakai Chemical Co., Ltd.
Inorganic filler 9: Barium sulfate B-65 manufactured by Sakai Chemical Co., Ltd.
Solvent 1: Ethylene glycol monobutyl ether acetate
Solvent 2: Diethylene glycol monoethyl ether acetate
Solvent 3: Diethylene glycol monobutyl ether acetate
Hardener 1: Baxenden blocked isocyanate BI7960
Hardener 1: Baxenden blocked isocyanate BI7982
Curing catalyst: KS1260 manufactured by Kyodo Yakuhin Co., Ltd.
Dispersant 1: Disperbyk 167 manufactured by Big Chemie Japan Co., Ltd.
Additive 1: Carboxylic acid amine salt

The conductive film of the present invention is obtained by drying and solidifying a conductive paste composed of a conductive filler, a binder resin and a solvent, and since there are no specific defects on the surface, it is excellent in laser etching processing and has excellent L / S. Since it is possible to form fine lines of 50/50 μm or less in good yield, it can be applied to all applications for forming fine circuits by applying printing technology, especially for touch panels, displays, digitizers, antistatic, etc. Can be used in the field.

1a, 2a, 3a, 4a: Terminals 1a, 2a, 3a, 4a, respectively
1b, 2b, 3b, 4b: Fine lines 1b, 2b, 3b, 4b, respectively
1c, 2c, 3c, 4c: Terminals 1c, 2c, 3c, 4c, respectively

Claims (10)

In a conductive film composed of a conductive composition composed of a conductive filler and a binder resin, the presence density of ring-shaped dent defects having a diameter of 50 μm or less on the surface of the film is 50 particles / cm2 or less, and the conductive composition is described. The substance contains silver particles having an average particle diameter of 0.3 μm or more and 6 μm or less, ion-catching agent particles having an average particle diameter of 0.13 μm or more and 0.85 μm or less, and a polymer binder resin, and further having an average particle diameter of 5 nm or more. A conductive film containing carbon particles of 200 nm or less or silicon dioxide particles having an average particle diameter of 5 nm or more and 200 nm or less, and substantially free of a solvent. The conductive film according to claim 1, wherein the surface roughness Ra of the portion of the conductive film having no ring-shaped dent is 0.1 or more and 1.0 μm or less. The conductive film according to claim 1 or 2, wherein the average film thickness of the conductive film is 2 μm or more and 20 μm or less. A method for forming electrical wiring, which comprises a process of removing a part of the conductive film according to any one of claims 1 to 3 by means of a light flux of excitation light. At least (B) metal particles with an average particle size of 0.3 μm or more and 6 μm or less, and (G) carbon or silicon dioxide particles with an average particle size of 5 nm or more and 200 nm or less.
(H) Ion catching agent particles having an average particle diameter of 0.13 μm or more and 0.85 μm or less,
(A) Polymer binder resin ,
(E) A conductive paste for laser etching processing, which comprises a solvent. The claim is characterized in that the polymer binder resin is one or a mixture of two or more selected from the group consisting of polyester resin, polyurethane resin, epoxy resin, phenoxy resin, vinyl chloride resin, and fibrous derivative resin. Item 5. The conductive paste for laser etching processing according to Item 5. The conductive paste for laser etching according to claim 5 or 6, wherein the polymer binder resin has a number average molecular weight of 5,000 to 60,000 and a glass transition temperature of less than 120 ° C. .. The solvent is a mixture of at least two kinds of solvents having different boiling points, and the boiling point of the first solvent occupying 45 to 90% by mass of the total amount of the solvent is 200 ° C. or higher and 270 ° C. or lower, and the second solvent. The conductive paste for laser etching processing according to any one of claims 5 to 7, wherein the boiling point is lower than the boiling point of the first solvent by 10 ° C. or more and is 55 to 10% by mass of the total amount of the solvent. The conductive paste for laser etching processing according to any one of claims 5 to 8, wherein the polymer binder resin has an acid value of less than 200 equivalents / ¹⁰⁶ g. The conductive paste for laser etching processing according to any one of claims 5 to 9, wherein the number of coarse silver particles of 15 μm or more is 100 or less per 1.0 g of the paste.

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