JPWO2013175965A1 - Conductive composition and circuit board on which conductive film is formed - Google Patents

Abstract

A conductive composition for forming a conductive film having good electrical characteristics, and a circuit board on which a conductive circuit is formed with high productivity and low cost by such a conductive composition are provided by a new light baking technique. A conductive composition containing conductive fine particles in a solvent for firing by light irradiation, characterized by containing a photoreaction initiator or a photoacid generator. In a preferred embodiment, the conductive composition further contains a dispersant, and the solvent is an organic solvent, water, or a mixture thereof. A coating substrate obtained by applying and drying the conductive composition can be irradiated with light using a flash lamp or the like to produce a circuit board on which a conductive circuit is formed by firing the conductive composition. it can.

Description

  The present invention relates to a conductive composition and a circuit board on which a conductive film is formed, and more specifically, a conductive circuit pattern of a printed wiring board, a conductive circuit pattern formed on a front substrate and a rear substrate of a plasma display panel, and the like. The present invention relates to a conductive composition that can be baked by light irradiation using a flash lamp useful for forming a film.

  Conventionally, a thermosetting conductive resin composition has been widely used for forming electrodes of resistance film type touch panels, circuit patterns of printed wiring boards, and the like by applying or printing on a film substrate or a glass substrate and curing by heating. ing. In addition, for the formation of conductor patterns in plasma display panels, fluorescent display tubes, electronic parts, etc., pattern formation is generally performed by screen printing using a conductive paste containing a very large amount of metal powder or glass powder. .

  However, in such a method, since heating and baking at high temperature are necessary, there is a difficulty in that the substrate is limited to a material that is not affected by high temperature. Many of the lower cost or flexible substrates, such as cellulose (paper), polyethylene terephthalate (PET), polyester, and many other plastics, cannot withstand these temperatures. Similarly, other components on the substrate, such as organic semiconductors, can also decompose at high temperatures.

  In recent years, a so-called photobaking technique has been developed and attracts attention as a means for solving such problems. For example, in Patent Document 1, a dispersion containing at least nanoparticles having a particle size of less than 1 μm is pattern-printed on a substrate and irradiated with pulsed light emission, whereby some of the nanoparticles including most metal nanoparticles are included. Disclosed is a method for forming a circuit pattern in which particles exhibit behavior as a black body, exhibit high electromagnetic radiation absorption, and have a small thermal mass so that the particles are rapidly heated and fused to form a cured circuit pattern. ing. In the case of this method, since the thermal conductivity of the substrate is poor and the pulse length is short, only a minimum amount of energy is transmitted to the substrate, so that the problems of the conventional methods of thermosetting and baking can be solved.

Special table 2008-522369

  According to the so-called photobaking technique described above, the problems of the conventional methods of thermosetting and baking can be solved, but there is a problem that it is difficult to obtain good electrical characteristics, and it is not widely put into practical use at present. .

The present invention has been made in view of such problems of the prior art. The basic object of the present invention is to provide a conductive composition for forming a conductive film having good electrical characteristics as a new light. It is to be provided by a firing technique.
Another object of the present invention is to provide a circuit board on which a conductive film is formed with good productivity and low cost by such a conductive composition.

In order to achieve the above object, it has been found that in the technique of firing a conductive composition by light irradiation, the electrical properties of the conductive composition can be improved by using a photoreaction initiator or a photoacid generator.
That is, according to the present invention, a conductive composition containing conductive fine particles in a solvent for firing by light irradiation, characterized by containing a photoreaction initiator or a photoacid generator. A conductive composition is provided.
In a preferred embodiment, the conductive composition further contains a dispersant, and the solvent is an organic solvent, water, or a mixture thereof.

  Furthermore, according to the present invention, there is provided a circuit board characterized by having a conductive film formed by irradiating a coating film obtained by applying and drying the conductive composition.

As described above, the conductive composition of the present invention has the greatest feature in that it contains a photoreaction initiator or a photoacid generator in the conductive composition for firing by light irradiation. As a result, a conductive film such as a circuit pattern having good electrical characteristics can be formed.
This is not necessarily clear, but photoinitiators have the property of being excited by absorbing light energy, so the coexistence of the photoinitiator makes it possible to absorb the light energy of the conductive fine particles themselves. It is thought that it can improve. Thereby, it is considered that the particles are rapidly heated, fused and fired to exhibit good conductivity.
On the other hand, when the composition contains a photoacid generator, it is considered that the photoacid generator functions as a surface treatment agent for the conductive fine particles, thereby exhibiting good conductivity.

  In the case of the method using the conductive composition of the present invention, a conductor circuit can be formed by irradiating the conductive composition patterned on the substrate with light, so that the conductor circuit can be produced with high productivity and at low cost. Can be provided. In addition, according to the method using the conductive composition of the present invention, since a minimum amount of energy is transmitted to the substrate, there is an advantage that the usable substrate is not limited.

Hereinafter, each component of the conductive composition of the present invention will be described.
As the conductive fine particles used in the conductive composition of the present invention, silver (Ag), gold (Au), nickel (Ni), copper (Cu), aluminum (Al), tin (Sn), lead (Pb) , Zinc (Zn), iron (Fe), platinum (Pt), iridium (Ir), osmium (Os), palladium (Pd), rhodium (Rh), ruthenium (Ru), tungsten (W), molybdenum (Mo) And metal such as tin and its alloys, metal oxides such as tin oxide (SnO ₂ ), indium oxide (In ₂ O ₃ ), ITO (Indium Tin Oxide), and carbon black, etc. Or it can use as 2 or more types of mixed powder. Moreover, in order to prevent the conductive fine particles from being oxidized and to improve the dispersibility in the composition, those treated with a fatty acid are preferred. Among the fatty acids, especially low-carbon carboxylic acids having 6 to 8 carbon atoms, specifically hexanoic acid, heptanoic acid, octanoic acid, sorbic acid, benzoic acid, salicylic acid, m-hydroxybenzoic acid, p-hydroxybenzoic acid. It is preferable that the length is about.
As the conductive fine particles, Cu, Ag, and Al are preferable, and Ag is more preferable.

  Various shapes such as a spherical shape, a flake shape, and a dendrite shape can be used as the shape of the conductive fine particles. In the conductive composition of the present invention, the primary particle size of the conductive fine particles may be less than 1 μm. More preferably, it is 300 nm or less, still more preferably 100 nm or less, particularly preferably 60 nm or less, and most preferably 20 nm or less.

  The primary particle diameter of the conductive fine particles is an average particle diameter calculated from 10 random conductive fine particles observed with an electron microscope.

  The compounding quantity of electroconductive fine particles will be 5 to 90 mass% of the whole electroconductive composition, Preferably it is 10 to 70 mass%, More preferably, it is 15 to 50 mass%. Proportion is appropriate. When the blending amount of the conductive fine particles is less than 5% by mass, the line width shrinkage or disconnection of the electrode circuit is likely to occur. On the other hand, when the blending amount exceeds 90% by mass, a stable and good dispersion (paste) is obtained. Since it becomes difficult to produce, it is not preferable.

  As the photoinitiator, any photoinitiator or sensitizer can be used as long as it can excite by absorbing light energy and can generate radicals, for example, regardless of the name. Can be used. Specific photoinitiators include alkylphenone compounds, benzoin compounds, acetophenone compounds, anthraquinone compounds, thioxanthone compounds, benzophenone compounds, xanthone compounds, tertiary amine compounds, oxime ester compounds, acylphosphine oxide compounds, titanocene. A compound etc. can be mentioned. Of these, alkylphenone and titanocene compounds are preferred.

Examples of the alkylphenone initiator include α-hydroxyalkylphenone compounds, α-aminoalkylphenone compounds, and ketal compounds.
Examples of commercially available α-hydroxyalkylphenone initiators include Irgacure (registered trademark) 127, Irgacure 184, Irgacure 2959, Darocur (registered trademark) 1173 manufactured by BASF Japan.

  Specific examples of the α-aminoalkylphenone initiator include 2-methyl-1- [4- (methylthio) phenyl] -2-morpholinopropanone-1, 2-benzyl-2-dimethylamino-1- ( 4-morpholinophenyl) -butan-1-one, 2- (dimethylamino) -2-[(4-methylphenyl) methyl] -1- [4- (4-morpholinyl) phenyl] -1-butanone, N, Examples include α-aminoacetophenone-based initiators such as N-dimethylaminoacetophenone, and commercially available products include Irgacure 369, Irgacure 379, and Irgacure 907 manufactured by BASF Japan.

  Specific examples of the ketal initiator include acetophenone dimethyl ketal and benzyl dimethyl ketal, and commercially available products include Irgacure 651 manufactured by BASF Japan.

Specific examples of the titanocene compound include bis (cyclopentadienyl) -bis [2,6-difluoro-3- (2- (1-pyr-1-yl) ethyl) phenyl] titanium, bis (cyclo Pentadienyl) -bis [2,6-difluoro-3-((2,5-dimethyl-1-pyr-1-yl) methyl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6 -Difluoro-3-((2-isopropyl-5-methyl-1-pyr-1,6-yl) methyl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3- ( (3-Trimethylsilyl-2,5-dimethyl-1-pyr-1-yl) methyl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3-((2,5 Dimethyl-3- (bis (2-methoxyethyl) aminomethyl) -1-pyr-1-yl) methyl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3-(( 2,5-bis (morpholinomethyl) -1-pyr-1-yl) methyl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,3,5,6-tetrafluoro-4- (3- (1-pyr-1-yl) propyl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3- (2- (4,5,6,7-tetrahydro-isoindole-2) -Yl) ethyl) phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3- (6- (9-carbazol-9-yl) hexyl) phenyl] titanium Bis (cyclopentadienyl) -bis [2,6-difluoro-3- (3- (2,3,4,5,6,7,8,9-octahydro-1-carbazol-9-yl) propyl) Phenyl] titanium, bis (cyclopentadienyl) -bis [2,6-difluoro-3- (2- (N-allylmethylsulfonylamino) ethyl) phenyl] titanium, bis (η ⁵ -2,4-cyclopentadiene -1-yl) -bis (2,6-difluoro-3- (1H-pyrrol-1-yl) phenyl) titanium and the like. Examples of commercially available products include Irgacure 784 manufactured by BASF Japan, which absorbs in the visible light region.

  The typical photoinitiators are listed above, but those that generate radically active species by light irradiation using a flash lamp or the like, and those that help the function of the growing species may be used. It is not limited. The blending amount of the photoinitiator (the total amount of the photoinitiator assistant and the sensitizer when contained) is 0.01 to 30% by mass with respect to the total mass of the photoinitiator and the conductive particles. The range is preferably 0.05 to 15% by mass, more preferably 0.1 to 5% by mass. When the blending amount of the photoreaction initiator is 0.01% by mass or more, the effect of the present invention can be obtained satisfactorily. However, exceeding 30% by mass is not preferable because it hinders firing.

  Any photoacid generator can be used regardless of its name as long as it can be excited by absorbing light energy to generate an acid, for example. Specific photoacid generators include, for example, diazonium salts, iodonium salts, bromonium salts, chloronium salts, sulfonium salts, selenonium salts, pyrylium salts, thiapyrylium salts, pyridinium salts and other onium salts; tris (trihalomethyl) -s -Triazines (eg 2,4,6-tris (trichloromethyl) -s-triazine), 2- [2- (5-methylfuran-2-yl) ethenyl] -4,6-bis (trichloromethyl) -s -Triazine, 2- [2- (furan-2-yl) ethenyl] -4,6-bis (trichloromethyl) -s-triazine, 2- (4-methoxyphenyl) -4,6-bis (trichloromethyl) ) -S-triazine, 2-methyl-4,6-bis (trichloromethyl) -s-triazine and other halogenated compounds; sulfonic acid 2-nitrobenzyl ester; iminosulfonate; 1-oxo-2-diazonaphthoquinone-4-sulfonate derivative; N-hydroxyimide = sulfonate; tri (methanesulfonyloxy) benzene derivative; bissulfonyldiazomethanes; sulfonylcarbonylalkanes; Examples include sulfonylcarbonyldiazomethanes; disulfone compounds; iron allene complexes. These photoacid generators can be used alone or in combination of two or more.

  Commercially available photoacid generators include CYRACURE UVI-6950, UVI-6970, manufactured by Union Carbide, and Optomer SP-150, SP-151, SP-152, SP-170, manufactured by ADEKA. Examples thereof include triarylsulfonium salts such as SP-171, CI-2855 manufactured by Nippon Soda Co., Ltd., and Decesa KI85B manufactured by Degussa, and unsubstituted or substituted aryldiazonium salts and diaryliodonium salts. Examples of the sulfonic acid derivative include PAI-101 (all are trade names) manufactured by Midori Chemical.

  The blending amount of such a photoacid generator is 0.01 to 30% by mass, preferably 0.05 to 15% by mass, more preferably 0.1% with respect to the total mass of the photoacid generator and the conductive particles. A range of ˜5% by weight is suitable. When the blending amount of the photoacid generator is 0.01% by mass or more, the effect of the present invention can be obtained satisfactorily. However, exceeding 30% by mass is not preferable because it hinders firing.

  In order to obtain a stable paste, it is preferable to add a dispersant suitable for the conductive fine particles to the conductive composition of the present invention. Examples of the dispersant include a compound having a polar group having an affinity for the conductive fine particles or a polymer compound, for example, an acid-containing compound such as a phosphate ester, a copolymer containing an acid group, a hydroxyl group-containing polycarboxylic acid ester, Polysiloxane, a long-chain polyaminoamide and a salt of an acid ester can be used. Examples of commercially available dispersants that can be suitably used include BYK (registered trademark) -101, -103, -108, -110, -112, -130, -184, -2001, -2020 (any (Made by Big Chemie). The amount of such a dispersant is 0.1 to 10% by mass, preferably 1 to 5% by mass, based on the total amount of the composition.

  In the conductive composition of the present invention, an organic solvent or water can be used as a solvent for dispersing conductive fine particles. Specific examples of the organic solvent include, for example, ketones such as methyl ethyl ketone and cyclohexanone; aromatic hydrocarbons such as toluene, xylene and tetramethylbenzene; cellosolve, methylcellosolve, carbitol, methylcarbitol, butylcarbitol, propylene Glycol ethers such as glycol monomethyl ether, dipropylene glycol monomethyl ether, dipropylene glycol monoethyl ether, triethylene glycol monoethyl ether; ethyl acetate, butyl acetate, cellosolve acetate, butyl cellosolve acetate, carbitol acetate, butyl carbitol acetate, Acetic esters such as propylene glycol monomethyl ether acetate; ethanol, propanol, ethylene glycol , Propylene glycol, terpineol (α-terpineol), alcohols such as isobornylcyclohexanol; aliphatic hydrocarbons such as octane and decane; petroleum solvents such as petroleum ether, petroleum naphtha, hydrogenated petroleum naphtha, and solvent naphtha These may be used alone or in combination of two or more. Among these, from the viewpoint of environmental hygiene, alcohols and water, particularly alcohols are preferable from the viewpoint of dispersion stability.

  The blending ratio of the solvent is not particularly limited as long as it is a quantitative ratio for obtaining a paste having good dispersion stability, but is 20 to 80% by mass, preferably 30 to 75% by mass of the total amount of the composition. %, More preferably 40 to 70% by mass. When the blending ratio of the solvent exceeds 80% by mass, it takes time for drying, and environmental hygiene problems due to evaporation of volatile components may occur.

  In the conductive composition of the present invention, a fluidity-imparting agent, a stabilizer, an antifoaming agent, a leveling agent, an anti-blocking agent, and a silane are added at a quantitative ratio that does not impair the effects of the present invention. Various additives such as coupling agents, thickeners, thixotropic agents, inorganic fillers, and coloring agents can also be added in small amounts.

  In the production of a circuit board, a conductive composition having the above-described composition is applied onto a substrate by a known coating method such as screen printing, ink jet, bar coater, blade coater, etc., for example, about 50-100 ° C. To form a coating film with a predetermined pattern. For pattern formation, a masking method, a resist, or the like can be used.

  Thereafter, the coating film having the predetermined pattern is irradiated with light using a flash lamp or the like. At this time, the conductive fine particles, which are the majority of the nanoparticles in the coating film, behave as a black body, exhibit a high light energy absorption rate, and heat the particles rapidly due to the small thermal mass of the particles. A conductive film having a circuit pattern that is fused and fired is formed.

There are no particular limitations on the substrate, and various types can be used. Specifically, a cellulose (paper) film, a polypropylene (PP) film, a polyester film, a resinous film such as a polyimide film, a glass substrate, a ceramic substrate, a BT (bismaleimide triazine) substrate, a glass epoxy substrate, Substrates such as a glass polyimide substrate, a phenol substrate, and paper phenol can be used.
Examples of the polyester film include a polyethylene terephthalate (PET) film and a polyethylene naphthalate (PEN) film.
Among these, the conductive composition of the present invention is preferably used for a resinous film or a substrate containing a resin.

  Firing by light irradiation is preferably light irradiation using a flash lamp. A flash lamp is a lamp in which a luminescent gas (Xe, Kr, Ar, Ne, etc.) is sealed in a tube made of quartz, glass, etc., and emits light for a very short time of light emission time of 1 μs to 5000 μs. Irradiation with a broad spectrum is possible. A xenon flash lamp in which Xe is enclosed is preferable because it is easily available.

  EXAMPLES Hereinafter, although an Example and a comparative example are shown and this invention is demonstrated concretely, it cannot be overemphasized that this invention is not limited to the following Example. In the following description, “part” is based on mass unless otherwise specified.

Examples 1 to 3 and Comparative Example 1
<Preparation of conductive paste>
Each component other than silver powder was blended at a blending ratio (mass ratio) shown in Table 1, and after mixing for 10 minutes with a stirrer, silver powder was blended and mixed for 10 minutes with a stirrer. Examples 1-3 and Comparative Examples 1 conductive pastes were obtained.

<Measurement of specific resistance value>
After masking with a cellophane adhesive tape with a gap of about 2 mm on the PET film, and applying a conductive paste with a scraper, the cellophane adhesive tape is peeled off and then removed at 80 ° C. for 30 minutes using a hot air circulating drying oven. Drying was performed. The film thickness of the obtained pattern was measured using a surf coder (SE-30H, manufactured by Kosaka Laboratories), and the pattern width was measured using MEASURING MICROSCOPE (manufactured by OLYMPUS, STM-MJS). A resistance value of 1 cm was measured using a DIGITAL MULTITIMER (CUSTORATION, CORDICATION CDM-26).
Next, using a photographic camera (Pocket Fujica 350 Flash manufactured by Fuji Film Co., Ltd.), the flash was irradiated from a height of 3 mm on the pattern, and then the resistance value of the pattern length of 1 cm was measured again.
The specific resistance value was calculated from the film thickness, pattern width, and resistance value measured above. The obtained results are shown in Table 2 below.

  As shown in Table 2, the conductive pastes of Examples 1 to 3 to which the photoinitiator was added had a specific resistance value that was lower than that of Comparative Example 1 to which no photoinitiator was added, and the conductive material. As good results.

Examples 4 and 5
Each component other than silver powder was blended at the blending ratio (mass ratio) shown in Table 3, and after mixing for 10 minutes with a stirrer, silver powder was blended and mixed for 10 minutes with a stirrer. Sex paste was obtained.
About each obtained electrically conductive paste, the specific resistance value was measured from the film thickness, the pattern width, and the resistance value like the above. The results are shown in Table 4.

  As shown in Table 4, the conductive pastes of Examples 4 and 5 to which the photoacid generator was added had a lower specific resistance value than that of Comparative Example 1 to which no photoacid generator was added, and the conductive material. As good results.

Claims (4)

  A conductive composition containing conductive fine particles in a solvent for firing by light irradiation, comprising a photoreaction initiator or a photoacid generator.   Furthermore, a dispersing agent is contained, The electrically conductive composition of Claim 1 characterized by the above-mentioned.   The conductive composition according to claim 1, wherein the solvent is an organic solvent, water, or a mixture thereof.   A circuit board comprising a conductive film formed by irradiating a coating film obtained by applying and drying the conductive composition according to any one of claims 1 to 3 on a substrate.