JP6111587B2 - Method for manufacturing conductive substrate - Google Patents

Description

  The present invention relates to a method for manufacturing a conductive substrate.

  Conventionally, for the production of circuit boards with conductive wiring on the base material, a photoresist is applied on the base material bonded with metal foil, the desired circuit pattern is exposed, and the pattern is formed by chemical etching. Have been used. According to the photoresist method, since the metal foil is used as the conductive wiring, a high-performance conductive substrate having a small volume resistivity can be manufactured. On the other hand, this method has a number of steps, is complicated, and has disadvantages such as requiring a photoresist material.

  On the other hand, by using a metal particle dispersion in which metal particles are dispersed, a pattern is printed directly on a substrate by a printing process such as screen printing or ink jet printing, and the metal particles are sintered. The method of forming is drawing attention. According to the technique of printing a pattern directly on a substrate, productivity is dramatically improved as compared with a conventional photoresist method or the like.

  It is known that the melting point of the metal particles dramatically decreases as the metal particles are refined. This is because the specific surface area of the particles increases and the surface energy increases as the particle size of the metal particles decreases. If this effect is utilized, the sintering of metal particles can proceed at a lower temperature than in the past, and circuit formation by printing is possible even for resin substrates with low heat resistance that have been difficult to use conventionally. Was expected to be possible. However, it is difficult to prepare a dispersion having better dispersibility and dispersion stability as the particle size of the metal particles is smaller.

Patent Document 1 describes a method of forming a circuit pattern with a conductive metal paste using an inkjet printing method. In Patent Document 1, in order to prevent the metal ultrafine particles from being in direct contact with each other, a compound having a group containing nitrogen, oxygen, and sulfur atoms capable of coordinative bonding with the metal element contained in the metal ultrafine particles, A technique for coating metal ultrafine particles is described. Alkylamine, alkanethiol, alkanediol, etc. are mentioned as a compound which has the group containing nitrogen, oxygen, and a sulfur atom utilized for the film of a metal surface. In Patent Document 1, specifically, a relatively low molecular weight compound having 4 to 20 carbon atoms is mentioned so that the alkylamine or the like is detached from the metal surface when the conductive metal paste is baked. Yes.
However, the technique of Patent Document 1 disperses metal particles using a low molecular weight compound, and the dispersion stability of the metal particles is insufficient. When the dispersion stability of the metal particles is insufficient, a metal film having good conductivity cannot be obtained even when fired.

  In Patent Document 2, a pattern is drawn on a substrate with a printed wiring board forming ink made of a dispersion containing metal oxide or metal hydroxide fine particles, and the metal oxide or metal hydroxide fine particles are drawn. A method of forming a conductive pattern by reducing at least a part is disclosed. According to the method of Patent Document 2, fine particles such as the metal oxide are reduced by energy irradiation or by combining energy irradiation and a reducing agent. Examples of the energy irradiation method include laser beams, electron beams, ion beams, and heat rays. However, in Patent Document 2, since a low molecular weight reducing agent is used, the reducing agent may suddenly boil at the time of high-power energy irradiation as described above, and the metal film may be damaged.

Patent Document 3 describes a metal particle dispersion containing a specific metal particle, a polymer dispersant having a specific polyester skeleton, and a dispersion medium.
According to Patent Document 3, it is described that the specific polymer dispersant exhibits a high effect on the dispersibility of the metal particles and is easily volatilized in a subsequent sintering step.

JP 2002-324966 A JP 2004-253794 A International Publication No. 2011/040189 Pamphlet

In order to improve the dispersibility and dispersion stability of the metal particles, when the metal particles are dispersed using a polymer dispersant as a dispersant, especially when fired at a low temperature or when fired in a short time In some cases, the polymer dispersant may remain in the metal film, the volume resistivity of the obtained substrate becomes high, and sufficient performance as a conductive substrate may not be obtained.
In the method of obtaining a metal film by firing metal particles, the firing temperature and oxidation of the metal particles have been problems. That is, when firing at a high temperature for a long time to remove the dispersant, sintering inhibition is likely to occur due to oxidation of the metal particles. There is also a need for a conductive substrate using a low heat resistant substrate. Therefore, there is a demand for a method for producing a conductive substrate having excellent conductivity while firing metal particles at a low temperature or in a short time.

  The present invention has been made under such circumstances, and provides a method for producing a conductive substrate in which an organic component having excellent conductivity is obtained with little remaining organic components in a film after baking. The purpose is to do.

As a result of intensive studies to achieve the above object, the inventors of the present invention formed a coating film using a metal particle dispersion for a conductive substrate containing metal particles and a specific dispersant, and applied pulsed light. By using and baking the said coating film, the metal oxidation was suppressed, the organic matter was hard to remain | survive, and the knowledge that the metal film which has the outstanding electroconductivity was obtained was acquired.
The present invention has been completed based on such knowledge.

The method for producing a conductive substrate according to the present invention comprises a metal particle for a conductive substrate containing metal particles, a dispersant containing a polyallylamine derivative having a structural unit represented by the following general formula (I), and a solvent. Preparing a dispersion;
A step of applying a coating liquid containing a metal particle dispersion for a conductive substrate on a base material to form a coating film,
And a step of firing the coating film to form a metal particle sintered film by irradiating with pulsed light.

（一般式（Ｉ）中、Ｒ^１は遊離のアミノ基、下記一般式（ＩＩ）、又は下記一般式（ＩＩＩ）で表される基を表し、複数あるＲ^１は同一であっても異なってもよい。但し、複数あるＲ^１のうち少なくとも１個は一般式（ＩＩＩ）で示される基である。）

(In the general formula (I), R ¹ represents a free amino group, a group represented by the following general formula (II) or the following general formula (III), and a plurality of R ¹ may be the same or different. Provided that at least ^one of the plurality of R ¹ is a group represented by the general formula (III).)

（一般式（ＩＩ）、及び一般式（ＩＩＩ）中、Ｒ^２は遊離のカルボン酸を有するポリエステル、遊離のカルボン酸を有するポリアミド、及び、遊離のカルボン酸を有するポリエステルアミドのいずれかからカルボキシ基を除いた残基を表す。）

(In General Formula (II) and General Formula (III), R ² represents a carboxy group from any of a polyester having a free carboxylic acid, a polyamide having a free carboxylic acid, and a polyester amide having a free carboxylic acid. (Represents a residue excluding)

  In the method for producing a conductive substrate of the present invention, it is preferable that the pulsed light is pulsed light of a xenon lamp from the viewpoint that metal oxidation is suppressed and organic matter hardly remains.

  In the manufacturing method of the electroconductive board | substrate of this invention, it is preferable from the point which is excellent in electroconductivity that the said metal particle is a metal particle containing 1 or more types chosen from gold | metal | money, silver, copper, and these oxides. .

  ADVANTAGE OF THE INVENTION According to this invention, the manufacturing method of the electroconductive board | substrate with which the remaining of the organic component in the film | membrane after baking can be obtained and the electroconductive board | substrate which has the outstanding electroconductivity can be obtained can be provided.

FIG. 1 is a schematic view showing an example of a conductive substrate obtained by the production method of the present invention.

  Hereinafter, the manufacturing method of the electroconductive board | substrate which concerns on this invention is demonstrated.

  The method for producing a conductive substrate according to the present invention comprises a metal particle for a conductive substrate containing metal particles, a dispersant containing a polyallylamine derivative having a structural unit represented by the following general formula (I), and a solvent. A step of preparing a dispersion, a step of applying a coating liquid containing a metal particle dispersion for a conductive substrate on a substrate, forming a coating film, and irradiating pulsed light to form the coating film And a firing process.

（一般式（Ｉ）中、Ｒ^１は遊離のアミノ基、下記一般式（ＩＩ）、又は下記一般式（ＩＩＩ）で表される基を表し、複数あるＲ^１は同一であっても異なってもよい。但し、複数あるＲ^１のうち少なくとも１個は一般式（ＩＩＩ）で示される基である。）

(In the general formula (I), R ¹ represents a free amino group, a group represented by the following general formula (II) or the following general formula (III), and a plurality of R ¹ may be the same or different. Provided that at least ^one of the plurality of R ¹ is a group represented by the general formula (III).)

（一般式（ＩＩ）、及び一般式（ＩＩＩ）中、Ｒ^２は遊離のカルボン酸を有するポリエステル、遊離のカルボン酸を有するポリアミド、及び、遊離のカルボン酸を有するポリエステルアミドのいずれかからカルボキシ基を除いた残基を表す。）

(In General Formula (II) and General Formula (III), R ² represents a carboxy group from any of a polyester having a free carboxylic acid, a polyamide having a free carboxylic acid, and a polyester amide having a free carboxylic acid. (Represents a residue excluding)

  According to the manufacturing method of the present invention, it is possible to provide a method for manufacturing a conductive substrate, in which a remaining organic component in the fired film is small and a conductive substrate having excellent conductivity can be obtained. Moreover, according to the manufacturing method of the present invention, a conductive substrate with reduced surface film roughness can be obtained.

Although there is an unexplained part as an action that exhibits the specific effect as described above by the specific combination, it is estimated as follows.
Conventionally, in the metal particle dispersion, a relatively low molecular weight dispersant has been used in order to suppress the remaining organic components during sintering. However, low molecular weight dispersants have insufficient dispersibility and dispersion stability. In addition, with a low molecular weight dispersant, when fired with pulsed light, the film is easily damaged by bumping of components, and the metal film is roughened. As described above, the metal film having a rough surface cannot provide good conductivity.
On the other hand, the metal particle dispersion used in the present invention is obtained by dispersing metal particles using a polyallylamine derivative having a structural unit represented by the general formula (I) as a dispersant. By stabilizing the nitrogen site by strongly adsorbing to the metal particles, the metal particles are less likely to agglomerate and are excellent in dispersibility and dispersion stability.
In addition, when the above specific dispersant is used, even when a metal film is formed by low-temperature firing, there is little residual dispersant, surface roughness of the film is reduced, and the resulting metal film has a volume resistivity. It has low and excellent conductivity. Although this mechanism is not yet elucidated, the use of the above-mentioned specific dispersants improves the dispersibility of metal particles compared to conventional polymer dispersants, and facilitates fusion by making the dispersed particles smaller. Is estimated. Moreover, it is estimated that the nitrogen part contained in the structural unit represented with general formula (I) has the reducibility and the oxidation inhibitory effect in the said specific dispersing agent. Furthermore, since the coating film of the coating liquid containing the metal particle dispersion using the specific dispersant has good uniformity and smoothness, it is estimated that the sintering proceeds uniformly. It is estimated that excellent electrical conductivity can be achieved by these synergistic effects. Furthermore, since the specific dispersant is easily decomposed or volatilized by irradiation with pulsed light and hardly remains in the metal film, it can be easily sintered even when irradiated with pulsed light for a very short time. Therefore, it is presumed that the oxidation of the metal particles can be suppressed also in this respect.

The method for producing a conductive substrate of the present invention comprises at least a step of preparing a metal particle dispersion for a conductive substrate, a step of forming a coating film, and a step of firing treatment, and the effect of the present invention. As long as the process is not impaired, other processes may be included as necessary.
Hereafter, each process of the manufacturing method of such an electroconductive board | substrate of this invention is demonstrated in order.

<Process for preparing metal particle dispersion for conductive substrate>
This step is a step of preparing a metal particle dispersion for a conductive substrate containing metal particles, a dispersant containing a polyallylamine derivative having a structural unit represented by the following general formula (I), and a solvent. .

（一般式（Ｉ）中、Ｒ^１は遊離のアミノ基、下記一般式（ＩＩ）、又は下記一般式（ＩＩＩ）で表される基を表し、複数あるＲ^１は同一であっても異なってもよい。但し、複数あるＲ^１のうち少なくとも１個は一般式（ＩＩＩ）で示される基である。）

(In the general formula (I), R ¹ represents a free amino group, a group represented by the following general formula (II) or the following general formula (III), and a plurality of R ¹ may be the same or different. Provided that at least ^one of the plurality of R ¹ is a group represented by the general formula (III).)

（一般式（ＩＩ）、及び一般式（ＩＩＩ）中、Ｒ^２は遊離のカルボン酸を有するポリエステル、遊離のカルボン酸を有するポリアミド、及び、遊離のカルボン酸を有するポリエステルアミドのいずれかからカルボキシ基を除いた残基を表す。）

(In General Formula (II) and General Formula (III), R ² represents a carboxy group from any of a polyester having a free carboxylic acid, a polyamide having a free carboxylic acid, and a polyester amide having a free carboxylic acid. (Represents a residue excluding)

  The said metal particle dispersion for conductive substrates is excellent in the dispersibility and dispersion stability of a metal particle by disperse | distributing a metal particle using the said specific dispersing agent. In addition, the polyallylamine derivative having the structural unit represented by the general formula (I) is easily decomposed or volatilized at the time of firing treatment with pulse light described later, and hardly remains in the sintered metal film. Moreover, it is estimated that the amino group which a polyallylamine derivative has, or the nitrogen atom derived from an amide bond decomposes | disassembles at the time of baking, and has the effect which suppresses the oxidation of a metal particle or reduces.

The metal particle dispersion for a conductive substrate obtained by this step contains at least metal particles, a dispersant, and a solvent, and other components as necessary as long as the effects of the present invention are not impaired. It may contain.
Hereinafter, each component of the metal particle dispersion for conductive substrates will be described in order.

(Metal particles)
In the present invention, the metal particles may be appropriately selected from metal particles that produce conductivity after firing. Examples of the metal type include gold, silver, copper, nickel, tin, iron, chromium, platinum, palladium, rhodium, iridium, ruthenium, osmium, indium, zinc, molybdenum, manganese, titanium, and aluminum. In the present invention, metal particles include particles in an alloy state, particles of a metal compound, and the like in addition to particles in a metal state. In addition, for example, when the surface of a metal particle is oxidized to form a metal oxide, or when two or more kinds of metals form a core-shell structure, the metal is contained in one particle. In addition, one or more of an alloy and a metal compound may be contained.
The metal particles are, among other things, metal particles containing at least one selected from gold, silver, copper, nickel, and oxides thereof because they have high conductivity and can easily maintain fine particles. Metal particles containing at least one selected from gold, silver, copper and oxides thereof are more preferable.

As said metal compound, a metal oxide, a metal hydroxide, an organometallic compound etc. are mentioned, for example. These metal compounds are preferably those which are decomposed during firing to be in a metal state. Examples of the metal compound having silver include silver oxide and organic silver compounds. Moreover, as a metal compound which has copper, copper oxides, such as cuprous oxide, cupric oxide, and these mixtures, etc. are mentioned, for example.
Examples of the alloy include a copper-nickel alloy, a silver-palladium alloy, a copper-tin alloy, a silver-copper alloy, and a copper-manganese alloy.
The metal particles may have a surface coated with an organic protective agent.

  A metal particle can be used individually by 1 type or in combination of 2 or more types among the metal particles containing 1 or more types of the said metal, an alloy, and a metal compound particle.

  What is necessary is just to select suitably the preparation method of the said metal particle from a conventionally well-known method. For example, a physical method of pulverizing metal powder by mechanochemical method, etc .; chemical dry method such as chemical vapor deposition method (CVD method), vapor deposition method, sputtering method, thermal plasma method, laser method; thermal decomposition method The metal particles can be obtained using a chemical wet method such as a chemical reduction method, an electrolysis method, an ultrasonic method, a laser ablation method, a supercritical fluid method, or a microwave synthesis method.

For example, in the vapor deposition method, fine particles are produced by bringing a vapor of a metal heated and brought into contact with a low vapor pressure liquid containing a dispersant under a high vacuum.
Further, as one type of chemical reduction method, there is a method in which a metal oxide and a reducing agent are mixed in a solvent in the presence of a complexing agent and an organic protective agent.

The complexing agent is a compound in which a donor atom of a ligand of the complexing agent and a metal ion or a metal atom are bonded to form a metal complex compound. Preferred examples of the donor atom include a nitrogen atom, an oxygen atom, and a sulfur atom. Examples of the complexing agent in which the nitrogen atom is a donor atom include, but are not limited to, nitrogen-containing heterocyclic compounds such as amines, imidazole, and pyridine.
The organic protective agent is used for dispersion stabilization of purified metal particles and particle size control, specifically, protein systems such as gelatin, gum arabic, and casein; starch, dextrin In addition to hydrophilic polymers such as hydroxyethyl cellulose; hydrophilic synthetic polymers such as polyvinyl alcohol; and relatively low molecular weight compounds such as fatty acids and alkylamines. Among these, from the viewpoint of dispersion stability, a protein-based organic protective agent is preferable.
In addition to the above method, commercially available metal particles can be used as appropriate.

The average primary particle size of the metal particles may be appropriately set according to the use, but is usually set in the range of 1 to 1000 nm. Especially, it is preferable that the average primary particle diameter of a metal particle is 2-500 nm from the point which is low viscosity, is excellent in a dispersibility and dispersion stability, and does not produce a precipitate easily.
The average primary particle size of the metal particles can be obtained by a method of directly measuring the size of the primary particles from an electron micrograph. Specifically, the minor axis diameter and major axis diameter of each primary particle were measured, and the average was taken as the particle diameter of the particle. Next, for each of 100 or more particles, the volume (mass) of each particle was obtained by approximating a rectangular parallelepiped having the obtained particle size, and the volume average particle size was obtained and used as the average particle size. Note that the same result can be obtained regardless of whether the electron microscope is a transmission type (TEM), a scanning type (SEM), or a scanning transmission type (STEM).

  In the metal particle dispersion for a conductive substrate of the present invention, the content of the metal particles may be appropriately selected depending on the use, but from the viewpoint of dispersibility, The content is preferably 95% by mass, and more preferably in the range of 20 to 90% by mass. In the present invention, when used in combination with a dispersant described later, the metal particles are excellent in dispersibility and dispersion stability even when the content of the metal particles is increased compared to the conventional case, and precipitates are generated. It can be difficult.

(Dispersant)
The dispersant used in the present invention is a dispersant containing a polyallylamine derivative having a structural unit represented by the following general formula (I).

（一般式（Ｉ）中、Ｒ^１は遊離のアミノ基、下記一般式（ＩＩ）、又は下記一般式（ＩＩＩ）で表される基を表し、複数あるＲ^１は同一であっても異なってもよい。但し、複数あるＲ^１のうち少なくとも１個は一般式（ＩＩＩ）で示される基である。）

(In the general formula (I), R ¹ represents a free amino group, a group represented by the following general formula (II) or the following general formula (III), and a plurality of R ¹ may be the same or different. Provided that at least ^one of the plurality of R ¹ is a group represented by the general formula (III).)

（一般式（ＩＩ）、及び一般式（ＩＩＩ）中、Ｒ^２は遊離のカルボン酸を有するポリエステル、遊離のカルボン酸を有するポリアミド、及び、遊離のカルボン酸を有するポリエステルアミドのいずれかからカルボキシ基を除いた残基を表す。）

(In General Formula (II) and General Formula (III), R ² represents a carboxy group from any of a polyester having a free carboxylic acid, a polyamide having a free carboxylic acid, and a polyester amide having a free carboxylic acid. (Represents a residue excluding)

  The nitrogen part of the structural unit represented by the general formula (I) and the metal particles are adsorbed, so that dispersibility and dispersion stability are improved. Therefore, the dispersed particle size of the metal particles can be reduced. it can. Moreover, when the said dispersing agent is used, the smoothness and uniformity of the coating film of the coating liquid containing a metal particle dispersion will be excellent. Therefore, sintering is likely to proceed uniformly. Moreover, the said dispersing agent is easy to be decomposed | disassembled thru | or volatilized by the baking process at the time of manufacturing an electroconductive board | substrate, and the remaining of an organic component is suppressed by the obtained electroconductive board | substrate. Moreover, the dispersant is less likely to cause film roughness even during pulsed light firing. Furthermore, since the nitrogen site has reducibility and suppresses the oxidation of the metal particles during firing, the metal film obtained after firing has less metal oxide. As a result, the obtained metal film is excellent in conductivity, and film roughness is reduced.

The polyallylamine derivative represented by the general formula (I) includes, for example, allylamine polymers and polyesters having a free carboxyl group, polyamides, or co-condensates of esters and amides (polyesteramides). It is obtained by reacting with one or more selected compounds.
More specifically, the polyallylamine derivative represented by the general formula (I) is represented by the following general formula (IV) or the following general formula (V) having an allylamine polymer and a free carboxyl group. It can be obtained by reacting an amino group and a carboxyl group using polyester and at least one selected from the group consisting of polyamides represented by the following general formula (VI) or the following general formula (VII).

（一般式（ＩＶ）中、Ｒ^３は、炭素原子数２〜２０の直鎖もしくは分岐のアルキレン基を表し、ａは２〜１００の整数である。複数あるＲ^３は、互いに同一であっても異なっていてもよい。）

(In the general formula (IV), R ³ represents a linear or branched alkylene group having 2 to 20 carbon atoms, and a is an integer of 2 to 100. A plurality of R ³ are mutually identical. May be different.)

（一般式（Ｖ）中、Ｒ^４は、炭素原子数２〜２０の直鎖もしくは分岐のアルキレン基、Ｃ_６Ｈ_４、又はＣＨ＝ＣＨを表し、Ｒ^５は、炭素原子数２〜２０の直鎖もしくは分岐のアルキレン基、又はポリアルキレングリコールから２つの水酸基を除いた残基を表し、ｂは２〜１００の整数であり、前記アルキレン基は、鎖中にエーテル結合を有してもよい。複数あるＲ^４及びＲ^５は、互いに同一であっても異なっていてもよい。）

(In the general formula (V), R ⁴ represents a linear or branched alkylene group having 2 to 20 carbon atoms, C ₆ H ₄ , or CH═CH, and R ⁵ has 2 to 20 carbon atoms. A linear or branched alkylene group or a residue obtained by removing two hydroxyl groups from polyalkylene glycol, b is an integer of 2 to 100, and the alkylene group may have an ether bond in the chain. The plurality of R ⁴ and R ⁵ may be the same as or different from each other.)

（一般式（ＶＩ）中、Ｒ^６は、炭素原子数２〜２０の直鎖もしくは分岐のアルキレン基を表し、ｃは２〜１００の整数である。複数あるＲ^６は、互いに同一であっても異なっていてもよい。）

(In General Formula (VI), R ⁶ represents a linear or branched alkylene group having 2 to 20 carbon atoms, and c is an integer of 2 to 100. A plurality of R ⁶ are the same as each other. May be different.)

（一般式（ＶＩＩ）中、Ｒ^４は、上記一般式（Ｖ）におけるＲ^４と同様である。Ｒ^７は、炭素原子数２〜２０の直鎖もしくは分岐のアルキレン基を表し、ｄは２〜１００の整数である。複数あるＲ^４及びＲ^７は、互いに同一であっても異なっていてもよい。）

(In the general formula (VII), ^{R 4} is, .R ⁷ is the same as ^{R 4} in the general formula (V) is a linear or branched alkylene group having a carbon number of 2 to 20, d is 2 It is an integer of ˜100. Plural R ⁴ and R ⁷ may be the same or different from each other.

  The polyallylamine derivative used in the present invention is an allylamine polymer, a polyester in which repeating components of the general formula (IV) and the general formula (V) are randomly polymerized, a repetition of the general formula (VI) and the general formula (VII). Manufactured by reacting a polyamide in which the components are randomly polymerized, and further a polyester amide in which the repeating components of the general formulas (IV) and / or (V) and general formulas (VI) and / or (VII) are randomly polymerized. be able to.

The polyallylamine derivative preferably contains 2 to 2500 repeating units represented by the general formula (I) as the main chain allylamine polymer, more preferably 2 to 1000, and more preferably 2 to 300. More preferred. Among them, as the allylamine polymer of the main chain, it is preferable to use a polyallylamine having a polymerization degree of 2 to 2500 which is an allylamine homopolymer, more preferably a polyallylamine having a polymerization degree of 2 to 1000, and further a polymerization degree of 2 More preferably, ~ 300 polyallylamine is used.
In the present invention, a polyallylamine having a polymerization degree of 2 to 1000, a polyester having a free carboxyl group, represented by the following general formula (IV) or (V), and represented by the following general formula (VI) or (VII): A polyallylamine derivative obtained by reacting one kind of polyamide to be used alone or in combination of two or more kinds is preferred.

The polyallylamine derivative used in the present invention is preferably a residue obtained by removing a carboxyl group from a polyester in which R ² has a free carboxylic acid. The polyester preferably has a number average molecular weight in the range of 300-20000, and more preferably in the range of 500-15000.
In the formula (I), the ratio of the group represented by the general formula (III) in the n R ¹ is preferably 60 to 95 mol%.

  Commercially available products of the polyallylamine derivatives include Azisper PB821, PB822, PB824, PB880 (manufactured by Ajinomoto Fine Techno).

  In this invention, what is necessary is just to set suitably content of the dispersing agent in the metal particle dispersion for conductive substrates in the range which does not impair the effect of this invention. Especially, it is preferable that it is 1-50 mass parts with respect to 100 mass parts of metal particles, and it is more preferable that it is 5-20 mass parts. If it is more than the said lower limit, the dispersibility and dispersion stability of a metal particle can be improved, and sedimentation can be suppressed. Moreover, if it is below the said upper limit, the residue of organic substance will be suppressed more and the electroconductive board | substrate excellent in electroconductivity can be obtained.

(solvent)
In the present invention, the solvent of the metal particle dispersion does not react with each component in the metal particle dispersion, and can be appropriately selected from organic solvents that can dissolve or disperse them. Specifically, alcohols such as methyl alcohol, ethyl alcohol, N-propyl alcohol, and isopropyl alcohol; ether alcohols such as methoxy alcohol, ethoxy alcohol, methoxyethoxyethanol, ethoxyethoxyethanol, and propylene glycol monomethyl ether; ethyl acetate, Esters such as butyl acetate, 3-methoxybutyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, ethyl lactate; ketones such as acetone, methyl isobutyl ketone, cyclohexanone; methoxyethyl acetate, methoxypropyl acetate, methoxybutyl acetate, Ethoxyethyl acetate, ethyl cellosolve acetate, methoxyethoxyethyl acetate, ethoxyethoxyethyl acetate Ether alcohol acetates such as tate and propylene glycol monomethyl ether acetate; ethers such as diethyl ether, ethylene glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether and tetrahydrofuran; N, N-dimethylformamide, N, N-dimethylacetamide, N -Aprotic amides such as methylpyrrolidone; lactones such as γ-butyrolactone; unsaturated hydrocarbons such as benzene, toluene, xylene and naphthalene; saturated hydrocarbons such as n-heptane, n-hexane and n-octane Organic solvents such as those of the system.

Among these, ether alcohols such as propylene glycol monomethyl ether; ether alcohol acetates such as methoxyethyl acetate, ethoxyethyl acetate, ethyl cellosolve acetate, methoxyethoxyethyl acetate, ethoxyethoxyethyl acetate, propylene glycol monomethyl ether acetate; ethylene Ether systems such as glycol dimethyl ether, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, and propylene glycol diethyl ether; ester systems such as 3-methoxybutyl acetate, methyl methoxypropionate, ethyl ethoxypropionate, and ethyl lactate can be suitably used. .
Among them, as the solvent used in the present invention, MBA (3-methoxybutyl acetate), PGMEA (propylene glycol monomethyl ether acetate), DMDG (diethylene glycol dimethyl ether), diethylene glycol methyl ethyl ether, PGME (propylene glycol monomethyl ether) or these can be used. What mixed is preferable from the point of the solubility of a dispersing agent, and the applicability | paintability.

  The content of the solvent in the metal particle dispersion of the present invention is not particularly limited as long as it can uniformly dissolve or disperse each component of the metal particle dispersion. In the present invention, the solid content in the metal particle dispersion is preferably in the range of 5 to 95% by mass, and more preferably in the range of 20 to 90% by mass. By being the said range, it can be set as the viscosity suitable for application | coating.

(Other ingredients)
The metal particle dispersion of the present invention may contain other components as necessary within a range not impairing the effects of the present invention.
Other components include, for example, complexing agents, organic protective agents, reducing agents, surfactants for improving wettability, silane coupling agents for improving adhesion, antifoaming agents, repellency inhibitors, and antioxidants. Agents, anti-aggregation agents, viscosity modifiers and the like. Moreover, as long as the effect of this invention is not impaired, the other dispersing agent may be contained.

(Method for producing metal particle dispersion)
In the present invention, the method for producing the metal particle dispersion may be any method that can disperse the metal particles satisfactorily, and can be appropriately selected from conventionally known methods. Specifically, for example, the dispersing agent is mixed and stirred in the solvent to prepare a dispersing agent solution, and then the dispersing agent solution is mixed with metal particles and other components as necessary. A metal particle dispersion can be prepared by dispersing using a stirrer or a disperser.
Examples of the disperser for performing the dispersion treatment include an ultrasonic disperser, a roll mill such as a two-roll, a three-roll, etc., an attritor, a Banbury mixer, a paint shaker, a kneader, a homogenizer, a ball mill, a sand mill, and a bead mill.

<Process for forming coating film>
This step is a step of forming a coating film by applying a coating liquid containing a conductive substrate metal particle dispersion on a substrate.

(Coating liquid containing metal particle dispersion for conductive substrate)
The coating liquid containing the conductive substrate metal particle dispersion can be used as it is as the coating liquid, but if necessary, a coating liquid can be added by adding a solvent or other components. It is good.
Examples of the solvent and other components include the solvents mentioned in the metal particle dispersion for conductive substrates, surfactants, silane coupling agents, antifoaming agents, anti-repelling agents, antioxidants, and aggregation inhibitors. Viscosity modifiers can be used. Furthermore, a resin binder such as an acrylic resin or a polyester resin may be added from the viewpoints of film forming properties, printability, and dispersibility within a range that does not impair the effects of the present invention.

(Base material)
What is necessary is just to select the base material used for this invention suitably from the base materials used for an electroconductive board | substrate according to a use. For example, soda lime glass, alkali-free glass, borosilicate glass, high strain point glass, quartz glass and other inorganic materials such as alumina and silica can be used, and polymer materials and paper can also be used. it can. Since the metal fine particle dispersion for conductive substrate used in the present invention can obtain a metal film having excellent conductivity even when baked at a temperature lower than conventional, soda lime glass or Even a polymer material can be suitably used, and is particularly useful in that a resin film can be used.

  Examples of the resin film include polyimide, polyamide, polyamideimide, polyethylene terephthalate (PET), polyethylene naphthalate (PEN), polyphenylene sulfide, polyether ether ketone, polyether sulfone, polycarbonate, polyether imide, epoxy resin, and phenol resin. , Glass-epoxy resins, polyphenylene ethers, acrylic resins, polyolefins such as polyethylene and polypropylene, polycycloolefins such as polynorbornene, and liquid crystalline polymer compounds.

  In addition, on the surface of the substrate, the shape of the pattern when the coating film of the coating liquid containing the metal particle dispersion is formed in a pattern is controlled, or the coating liquid coating film containing the metal particle dispersion You may perform the process for providing the adhesiveness between. The treatment method for the substrate surface can be appropriately selected from conventionally known methods. Specifically, for example, corona treatment, UV treatment, vacuum ultraviolet lamp treatment, dry treatment such as plasma treatment, amine silane coupling agent, imidazole silane coupling agent, titanium coupling agent, aluminum coupling agent treatment, etc. Chemical layer treatment, porous silica, porous membrane formation treatment such as cellulose-based receiving layer, active energy ray curable resin layer, thermosetting resin layer, thermoplastic resin layer and other resin layer formation treatment . By providing the substrate surface with liquid repellency by this treatment, when the coating film of the coating liquid containing the metal particle dispersion is formed in a pattern on the substrate, the wetting and spreading of the coating liquid is suppressed, and high-definition is achieved. A pattern can be formed. In addition, by forming an ink receiving layer such as a porous film on the surface of the substrate, it is possible to penetrate the solvent component and form a high-definition pattern. On the contrary, the applicability | paintability with respect to a base material can be improved by giving lyophilic property to the base-material surface. These treatments on the surface of the substrate can be used properly according to the purpose and purpose.

  What is necessary is just to select the shape of the said base material suitably according to a use, and although it may be flat form or may have a curved surface, it is usually flat form. In the case of using a flat substrate, the thickness of the substrate may be appropriately set according to the application, and may be, for example, about 10 μm to 1 mm.

(Application method)
What is necessary is just to select the method of apply | coating the said coating liquid on the said base material suitably from a conventionally well-known method. Examples include gravure printing, gravure offset printing, reverse offset printing, screen printing, spray coating, spin coating, comma coating, bar coating, knife coating, slot die coating, offset printing, flexographic printing, inkjet printing, dispenser printing, and the like. It is done. Among these, gravure printing, gravure offset printing, reverse offset printing, flexographic printing, screen printing, and inkjet printing are preferable because fine patterning can be performed. In particular, since the metal particle dispersion used in the present invention is excellent in dispersibility, it does not cause clogging or discharge bending of the inkjet discharge nozzle, and can be suitably used for inkjet printing. .

  The coating solution on the substrate may be dried by a usual method after printing. The film thickness of the printed portion after drying can be controlled by appropriately changing the coating amount, the average primary particle diameter of the metal particles, and the like, and may be appropriately adjusted according to the application. It is the range of 01-50 micrometers, Preferably, it is 0.1-20 micrometers.

<Step of firing the coating film>
This step is a step of firing the coating film by irradiating pulsed light (hereinafter sometimes referred to as pulsed light firing).
Pulsed light baking is a method of baking in an extremely short time by irradiation with pulsed light. Here, in the present invention, the pulsed light means light having a relatively short lighting time, and the lighting time is called a pulse width. The light source of the pulsed light is not particularly limited, and examples thereof include a flash lamp and a laser in which a rare gas such as xenon is sealed. Among these, it is preferable to irradiate light having a continuous wavelength spectrum from ultraviolet rays to infrared rays, preferably pulse light of a xenon lamp, and specifically, a xenon flash lamp is preferably used. When such a light source is used, the same effect as when UV irradiation is performed simultaneously with heating can be obtained, and baking can be performed in an extremely short time. In addition, when such a light source is used, by controlling the pulse width and irradiation energy, it is possible to heat only the coating film of the coating liquid containing the metal particle dispersion and the vicinity thereof, and to the substrate. The influence of heat can be suppressed.

In the present invention, the pulse width of the pulsed light may be adjusted as appropriate, but is preferably set between 1 μs and 10,000 μs, and more preferably within the range of 10 μs to 5000 μs. The irradiation energy per one pulse light is ^{preferably 0.1J / cm 2 ~100J / cm 2} , 0.5J / cm 2 ~50J / cm 2 is more preferable.
In pulsed light firing, the number of pulsed light irradiations may be appropriately adjusted according to the composition, film thickness, area, etc. of the coating film, and the number of times of irradiation may be only once or may be repeated two or more times. Good. Especially, it is preferable to set the frequency | count of irradiation to 1-100 times, and it is preferable to set it as 1-50 times. When the pulsed light is irradiated a plurality of times, the irradiation interval of the pulsed light may be adjusted as appropriate. In particular, the irradiation interval is preferably set within a range of 10 μsec to 2 seconds, and more preferably set within a range of 100 μsec to 1 second.
By setting the pulsed light as described above, it is possible to suppress the influence on the base material and to suppress the oxidation of the metal particles, and the dispersant contained in the metal particle dispersion also desorbs or decomposes. Therefore, it is possible to obtain a conductive substrate that is easily conductive and excellent in conductivity.

Such pulsed light baking can heat only the coating film of the coating liquid containing the metal particle dispersion and the vicinity thereof, and the coating film can be baked at a low temperature and in a short time. In addition, a smooth sintered metal particle film can be formed. In the pulsed light baking, the heating temperature and the processing depth can be controlled by appropriately adjusting the pulse width and irradiation energy of the pulsed light. As a result, a non-uniform film is rarely formed and grain growth can be prevented, so that a very dense and smooth film can be obtained. In addition, since firing is possible in an extremely short time, oxidation of the metal particles can be suppressed, and a sintered film having excellent conductivity can be obtained.
The pulsed light baking can be performed in the air under atmospheric pressure, but may be performed under an inert atmosphere, a reducing atmosphere, or under reduced pressure. Moreover, you may perform pulsed light baking, heating a coating film.

The thickness of the metal film of the conductive substrate thus obtained may be adjusted as appropriate according to the application, but the thickness is usually about 0.01 to 50 μm, and 0.05 nm to 30 μm. It is preferable that it is 0.1-20 micrometers.
The volume resistivity of the metal film is preferably 1.0 × 10 ⁻⁴ Ω · cm or less.

  In the production method of the present invention, a coating liquid containing a metal particle dispersion is applied in a pattern on a substrate to form a coating film, and the coating film is baked to form a patterned metal film. It may be a method for manufacturing a patterned conductive substrate.

  The conductive substrate obtained by the method for manufacturing a conductive substrate of the present invention has excellent conductivity because the remaining organic components after sintering are suppressed. An electronic member using such a conductive substrate can be effectively used for an electromagnetic wave shielding film having a low surface resistance, a conductive film, a flexible printed wiring board, and the like.

  Hereinafter, the present invention will be specifically described with reference to examples. These descriptions do not limit the present invention.

(Synthesis Example 1 Production of copper particles)
64 g of cupric oxide and 5.1 g of gelatin as an organic protective agent were added to 650 mL of pure water and mixed to prepare a mixed solution. The pH of the mixture was adjusted to 10 using 15% aqueous ammonia, and then heated from room temperature to 90 ° C. over 20 minutes. After raising the temperature, a mixture of 6.4 g of a 1% mercaptoacetic acid solution and 75 g of 80% hydrazine monohydrate in 150 mL of pure water was added as a complexing agent while stirring. Reaction with dicopper gave copper particles. When the obtained copper particles were observed with a scanning transmission electron microscope (STEM), the average primary particle size was 50 nm.

(Example 1 Production of conductive substrate 1)
(1) Preparation of metal particle dispersion 1 6 parts by mass of the copper particles of Synthesis Example 1 and a dispersant containing a polyallylamine derivative having a structural unit represented by the general formula (I) (Ajinomoto Fine-Techno, Ajisper PB880) 0.45 parts by mass (0.45 parts by mass in terms of solid content) and 8.55 parts by mass of PGMEA were mixed and pre-dispersed with a paint shaker (manufactured by Asada Tekko) for 1 hour with 2 mm zirconia beads, and further with 0 as main dispersion. 1 mm zirconia beads were dispersed for 4 hours to obtain a metal particle dispersion 1.

(2) Production of Conductive Substrate 1 The metal particle dispersion 1 obtained in the above (1) is applied on a polyimide film (trade name: Kapton 300H, manufactured by Toray DuPont, thickness 75 μm) with a wire bar. The film was dried at 100 ° C. for 15 minutes to give a coating film having a film thickness of 1 μm. Thereafter, using a pulsed xenon lamp device (SINTERON 2000 (manufactured by Xenon Corporation)), irradiation was performed once with a pulse width of 500 μsec and an applied voltage of 3.8 kV to obtain a conductive substrate 1.

(Example 2 Production of conductive substrate 2)
(1) Preparation of Metal Particle Dispersion 2 In Example 1 (1), instead of the copper particles of Synthesis Example 1, the silver particles (DOWA Electronics, T2S-A06, particle size 60 nm) were 3.75 parts by mass. In addition to the addition of 0.3 parts by mass of another dispersant (manufactured by Ajinomoto Finetechno, Azisper PB821) containing a polyallylamine derivative having a structural unit represented by the general formula (I) instead of Azisper PB880, Example In the same manner as in Example 1, a metal particle dispersion 2 was obtained.

(2) Production of conductive substrate 2 A conductive substrate in the same manner as in Example 1 except that the metal particle dispersion 2 was used in place of the metal particle dispersion 1 in Example 1 (2). 2 was obtained.

(Example 3 Production of conductive substrate 3)
(1) Preparation of Metal Particle Dispersion 3 In Example 1 (1), instead of the copper particles of Synthesis Example 1, silver particles (DOWA Electronics, T2S-A06, particle size 60 nm) were 3.75 parts by mass. In addition to the addition of 0.3 parts by mass of another dispersant (Ajinomoto Finetechno, Azisper PB824) containing a polyallylamine derivative having a structural unit represented by the general formula (I) instead of Azisper PB880, Examples In the same manner as in Example 1, a metal particle dispersion 3 was obtained.

(2) Production of conductive substrate 3 A conductive substrate in the same manner as in Example 1 except that the metal particle dispersion 3 was used in place of the metal particle dispersion 1 in (2) of Example 1. 3 was obtained.

(Comparative Example 1 Production of Comparative Conductive Substrate 1)
The metal particle dispersion 2 obtained in (1) of Example 2 was applied on a glass substrate (trade name: OA-10G, manufactured by Nippon Electric Glass Co., Ltd., thickness 0.7 mm) with a wire bar at 80 ° C. The film was dried for 15 minutes to give a coating film having a thickness of 2 μm. The obtained coating film was baked for 30 minutes in a mixed gas atmosphere of 300 ° C., 3% by volume of hydrogen / 97% by volume of nitrogen, and the comparative conductive substrate 1 was obtained.

(Conductivity evaluation)
Using a surface resistance meter ("Loresta GP" manufactured by Dia Instruments, PSP type probe), the four probes are brought into contact with the metal films of the conductive substrates of the above examples and comparative examples, and the sheet resistance value is obtained by the four probe method. Was measured. The results are shown in Table 1. The lower the sheet resistance value, the better the conductivity. The upper limit of sheet resistance measured by this measurement method was 10 ⁸ Ω / □.

[Summary of results]
From the results of Examples 1 to 3, a coating formed using a coating liquid containing metal particles and a metal particle dispersion having a dispersant containing a polyallylamine derivative having a structural unit represented by the general formula (I). A conductive substrate having excellent conductivity could be obtained by firing the film by irradiating it with pulsed light.
Moreover, when the electroconductive board | substrate obtained by Examples 1-3 was observed visually, the film | membrane roughness of the surface was not recognized. By using a metal particle dispersion having a dispersant containing a polyallylamine derivative having a structural unit represented by the general formula (I), film roughness can be reduced even by baking treatment using pulsed light, which has been easy to occur. It became clear that it did not occur.
In the conductive substrate of Comparative Example 1 subjected to hydrogen gas firing, the dispersant component remained. The polyallylamine derivative having the structural unit represented by the general formula (I) is presumed to be hardly decomposed by baking with hydrogen gas.
From such a result, by combining a metal particle and a fine particle dispersion for a conductive substrate containing a dispersant containing a polyallylamine derivative having a structural unit represented by the general formula (I) and pulsed light firing, It was revealed that a conductive substrate having excellent conductivity and no surface film roughness can be obtained.

1 Base material 2 Metal film 100 Substrate

Claims (3)

Preparing a metal particle dispersion for a conductive substrate containing metal particles, a dispersant containing a polyallylamine derivative having a structural unit represented by the following general formula (I), and a solvent;
A step of applying a coating liquid containing a metal particle dispersion for a conductive substrate on a base material to form a coating film,
And a step of firing the coating film to form a metal particle sintered film by irradiating with pulsed light.

(In the general formula (I), R ¹ represents a free amino group, a group represented by the following general formula (II) or the following general formula (III), and a plurality of R ¹ may be the same or different. Provided that at least ^one of the plurality of R ¹ is a group represented by the general formula (III).)

(In General Formula (II) and General Formula (III), R ² represents a carboxy group from any of a polyester having a free carboxylic acid, a polyamide having a free carboxylic acid, and a polyester amide having a free carboxylic acid. (Represents a residue excluding)   The method for manufacturing a conductive substrate according to claim 1, wherein the pulsed light is pulsed light of a xenon lamp.   The manufacturing method of the electroconductive board | substrate of Claim 1 or 2 whose said metal particle is a metal particle containing 1 or more types chosen from gold | metal | money, silver, copper, and these oxides.

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