JP6277751B2 - Copper particle dispersion paste and method for producing conductive substrate - Google Patents

Description

  The present invention relates to a copper particle-dispersed paste and a method for producing a conductive substrate using these.

  A method of forming a circuit pattern by printing a pattern directly on a base material by a printing process such as screen printing or ink jet printing using a metal particle dispersion in which metal particles are dispersed, and sintering the metal particles. Attention has been paid. 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. Is expected to be possible. However, as the particle size of the metal particles is reduced, aggregation tends to occur, dispersibility and dispersion stability cannot be ensured, and there is a problem in application suitability such that scumming and streaks occur during application. If there is a problem in coating suitability and a highly uniform coating film cannot be formed, the accuracy of the circuit pattern will deteriorate, the metal particles will not be present uniformly and densely, and the conductivity after sintering will deteriorate. Thus, it has been difficult in the past to achieve both dispersion stability and coating suitability of the metal particle dispersion and low-temperature sintering.

  Further, a metal particle dispersion using silver particles is difficult to oxidize and is excellent in conductivity, but silver itself is expensive or has problems of ion migration. Therefore, development of a metal particle dispersion using copper as an inexpensive metal with excellent migration resistance is required. However, since copper particles are generally more easily oxidized than silver particles, there is a problem that conductivity is difficult to be expressed.

As a method for printing a pattern directly on a substrate, when a printing method suitable for thick film formation such as screen printing is used, a metal particle-dispersed paste having a high solid content concentration or high viscosity is used.
In Patent Document 1, in a conductive paste having conductive powder, an organic binder, an additive, and a solvent as essential components, a thermosetting resin and a hydroxystyrene type having a weight average molecular weight of 1,000 to 2,000,000 are used as the organic binder. A conductive paste containing a polymer and / or a derivative thereof and containing benzoic acid and / or a derivative thereof as the additive is described. According to Patent Document 1, it is described that a conductive coating film excellent in conductivity, adhesion, and printability can be formed by applying or printing the conductive paste and then heat-curing.
However, in the technique of Patent Document 1, it is essential to include a thermosetting resin. The conductive paste containing a thermosetting resin exhibits conductivity by bringing particles into contact with each other by curing shrinkage of the resin during heating. In the case of using copper particles, conductivity is developed while suppressing oxidation by curing with a thermosetting resin, but in order to increase the contact points between particles, substantially deformed particles are used, so dispersibility and application suitability are increased. There was a problem. In addition, because of the contact between particles, there is a limit to the conductivity that can be expressed. On the other hand, as in the case of using nanoparticles, when the particles are sintered to express conductivity, the thermosetting resin becomes a factor that inhibits the sintering.

Patent Document 2 discloses a conductive material obtained by uniformly mixing copper powder, fine copper powder, and a copper salt of an aliphatic monocarboxylic acid dissolved in (dialkylamino) alkylamine together with an aliphatic polyhydric alcohol as a dispersion solvent. Or conductive paste obtained by uniformly mixing copper particles dispersed in copper powder and fine copper powder and further (dialkylamino) alkylamine together with aliphatic polyhydric alcohol as a dispersion solvent. According to Patent Document 2, it is described that it does not use a thermosetting resin or glass frit to maintain adhesion to the underlayer and electrical contact with the underlayer, and is suitable for the production of a thick conductor layer. ing.
In the technique of Patent Document 2, micron-sized copper powder is filled with fine copper powder or copper particles, and the heat treatment at 300 ° C. or higher is used to fuse the copper particles with the copper powder, thereby fusing the copper particles together. This increases the contact area between copper powders and reduces the resistivity. However, since the method of Patent Document 2 does not include a component corresponding to the binder resin, there is a problem in that paste applicability is poor. Further, when the conductive paste is used, the sintering temperature is high, and it is necessary to further lower the sintering temperature for use on a low heat-resistant film such as a PET film.

On the other hand, the present inventors have disclosed in Patent Document 3 a dispersion containing metal fine particles, a dispersant, and a dispersion medium as a metal fine particle dispersion having low viscosity and improved ink jet suitability, and the molecular weight of the dispersant is 300. Disclosed are fine metal particle dispersions that are ˜500 aliphatic alcohol polyether compounds and / or aliphatic amine polyether compounds.
Since the metal fine particle dispersion of Patent Document 3 has a low viscosity, it is difficult to increase the thickness of the film, and it is easy to wet and spread, so that fine lines cannot be drawn and fine patterning is difficult.

JP 2012-72418 A JP 2013-47365 A JP 2012-214641 A

As described above, the conductive paste using copper powder has a problem that it is easy to oxidize compared to silver and it is difficult to reduce resistance. In order to reduce resistance, thermosetting resins are used as binders to cure while suppressing oxidation, or pastes that do not contain binders have been proposed, but paste dispersibility and application suitability, especially printability, have been proposed. There was a problem. A copper particle-dispersed paste excellent in copper particle dispersibility and coating suitability and capable of forming a film having high conductivity after firing at a low temperature or in a short time has not been obtained.
The present invention has been made under such circumstances, and is excellent in dispersibility and coating suitability, a copper particle-dispersed paste capable of forming a film having high conductivity after firing at a low temperature or in a short time, and a low temperature Alternatively, an object of the present invention is to provide a method for producing a conductive substrate, which can obtain a conductive substrate having good pattern accuracy and excellent conductivity by baking in a short time.

As a result of intensive studies to achieve the above object, the present inventors have combined a thermoplastic resin with copper particles having an average particle diameter of 10 nm to 1 μm, and when making a paste having a specific high viscosity, By using a tertiary amine having a specific structure having a weight average molecular weight of 3000 or less as a dispersant, the dispersibility of the copper particles and the coating suitability are excellent, and even when baked at a low temperature or in a short time, it is high. The knowledge that the film which has electroconductivity can be formed was acquired.
The present invention has been completed based on such knowledge.

Moreover, the copper particle-dispersed paste according to the present invention comprises copper particles having an average particle size of 10 nm to 1 μm, a tertiary amine having a weight average molecular weight of 3000 or less represented by the following general formula (I), a thermoplastic resin, contains a solvent state, and are shear rate of 1000 (1 / s) measured viscosity is 50 mPa · s or higher at 25 ° C., the relative copper particles 100 parts by weight, the thermoplastic resin is 1 to 25 mass and wherein the part der Rukoto.
The method for producing a conductive substrate according to the present invention includes a copper particle having an average particle size of 10 nm to 1 μm, a tertiary amine having a weight average molecular weight of 3000 or less represented by the following general formula (I), a thermoplastic resin, contains a solvent state, and are shear rate of 1000 (1 / s) measured viscosity is 50 mPa · s or higher at 25 ° C., the relative copper particles 100 parts by weight, the thermoplastic resin is 1 to 25 mass the parts der Ru copper particles dispersed paste, and a step of forming a coating film by coating on a substrate, characterized by a step of firing the coating film.

（Ｒ^１は炭素数１〜２０の脂肪族炭化水素基である。Ｒ^２及びＲ^３はそれぞれ独立に、炭素数１〜２０の脂肪族炭化水素基、又は、−（ＣＨ_２ＣＨ_２Ｏ）_ｎ−（ＣＨ_２ＣＨ（ＣＨ_３）Ｏ）_ｍ−Ｈで表される基（ｍ、ｎは０以上の整数であり、ｍ及びｎの少なくとも１つは１以上）である。）

(R ¹ is an aliphatic hydrocarbon group having 1 to 20 carbon atoms. R ² and R ³ are each independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms or — (CH ₂ CH ₂ O). _n— (CH ₂ CH (CH ₃ ) O) _m —H (m, n is an integer of 0 or more, and at least one of m and n is 1 or more).

  In the copper particle-dispersed paste and the method for producing a conductive substrate according to the present invention, the tertiary amine is 1 to 10 parts by mass, and the thermoplastic resin is 1 to 25 parts by mass. This is preferable from the viewpoint of excellent coating suitability and low-temperature sintering properties.

  In the copper particle-dispersed paste and the method for producing a conductive substrate according to the present invention, it is preferable that the thermoplastic resin contains a phenoxy resin, and it is preferable that the thermoplastic resin is a phenoxy resin. When a phenoxy resin is used as the thermoplastic resin, the printability is excellent and the pattern resolution is excellent.

  In the method for manufacturing a conductive substrate according to the present invention, the baking step may be a step of baking by surface wave plasma generated by application of microwave energy or a step of baking by irradiation with flash light. From the viewpoint of excellent low-temperature sinterability.

  According to the present invention, a copper particle-dispersed paste that is excellent in dispersibility and coating suitability and can form a film having high conductivity after baking at low temperature or in a short time, and pattern accuracy by baking at low temperature or in a short time Therefore, it is possible to provide a method for manufacturing a conductive substrate, which can provide a conductive substrate having good conductivity and excellent conductivity.

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

Hereinafter, the copper particle dispersion paste according to the present invention and the method for producing a conductive substrate will be described.
In the present invention, (meth) acryl represents each of acryl and methacryl, and (meth) acrylate represents each of acrylate and methacrylate.

[Copper particle dispersion paste]
The copper particle-dispersed paste according to the present invention includes copper particles having an average particle size of 10 nm to 1 μm, a tertiary amine having a weight average molecular weight of 3000 or less represented by the following general formula (I), a thermoplastic resin, and a solvent. And a viscosity measured at a shear rate of 1000 (1 / s) at 25 ° C. is 50 mPa · s or more.

（Ｒ^１は炭素数１〜２０の脂肪族炭化水素基である。Ｒ^２及びＲ^３はそれぞれ独立に、炭素数１〜２０の脂肪族炭化水素基、又は、−（ＣＨ_２ＣＨ_２Ｏ）_ｎ−（ＣＨ_２ＣＨ（ＣＨ_３）Ｏ）_ｍ−Ｈで表される基（ｍ、ｎは０以上の整数であり、ｍ及びｎの少なくとも１つは１以上）である。）

(R ¹ is an aliphatic hydrocarbon group having 1 to 20 carbon atoms. R ² and R ³ are each independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms or — (CH ₂ CH ₂ O). _n— (CH ₂ CH (CH ₃ ) O) _m —H (m, n is an integer of 0 or more, and at least one of m and n is 1 or more).

In the present invention, a copper resin having a specific average particle diameter is combined with a thermoplastic resin to form a paste, and further, a tertiary amine having a specific structure and molecular weight is combined. It is estimated that the specific effects as described above are exhibited.
In the present invention, in order to obtain high conductivity using copper particles that are easily oxidized, attention was paid to a copper particle-dispersed paste that is difficult to be oxidized and can be fired at a low temperature or in a short time. When a thermosetting resin is used as a binder resin, high temperature heating is required and sintering of copper powder is inhibited. Therefore, in the present invention, application suitability is imparted in order to form a paste having a specific viscosity. However, a thermoplastic resin that hardly inhibits the sintering of the copper particles is combined. In the paste-like solvent and thermoplastic resin having a predetermined high viscosity, the copper particles are not easily settled but are likely to aggregate. In order to impart dispersibility of the copper particles, it is desirable to use a compound having a functional group that strongly adsorbs to the copper particle surface. On the other hand, if the compound is adsorbed too strongly, the compound is removed from the copper particles in the firing step. It becomes difficult to separate, and as a result, it is considered that it becomes a factor of conductivity deterioration. In that regard, in the present invention, a tertiary amine having a specific structure with a relatively low molecular weight, which adsorbs relatively weakly on the surface of the copper particles, is combined. The specific tertiary amine has sufficient affinity for the thermoplastic resin by the aliphatic hydrocarbon chain or alkylene oxide chain, but can be adsorbed relatively weakly on the surface of the copper particle at the nitrogen site. While improving the dispersibility in a plastic resin, it is excellent also in the detachability at the time of baking. As described above, since the copper particles can be uniformly dispersed in the thermoplastic resin, the coating suitability is improved and the pattern accuracy at the time of pattern printing is increased. In addition, since the aliphatic hydrocarbon chain or alkylene oxide chain of the specific tertiary amine has a structure that is easily decomposed during firing, it is estimated that it will have excellent conductivity when fired at a low temperature or in a short time. The
Furthermore, it is presumed that in the present invention, the effect of suppressing oxidation of the copper particles is enhanced by the specific tertiary amine adhering to the surface of the copper particles. Therefore, it is estimated that sintering inhibition due to oxidation during firing hardly occurs, and a film having high conductivity can be formed after firing.

The coated copper particles and copper particle dispersion of the present invention may contain other components in addition to the above essential components as long as the effects of the present invention are not impaired.
Hereinafter, each component of the copper particle dispersion paste of the present invention will be described in detail in order.

<Copper particles>
In the present invention, the copper particles are typically metallic copper particles. However, since copper is a metal that is very easily oxidized, the surface of the metallic copper particles is partially oxidized into an oxide. Cases may be included.

In the present invention, copper particles having an average particle diameter of 10 nm to 1 μm are used. When the thickness is less than 10 nm, a large amount of a dispersant and a binder resin are required to impart dispersion stability and coating suitability, resulting in deterioration of conductivity. On the other hand, if it is larger than 1 μm, sintering at a low temperature is difficult to proceed, and there is a problem in printability of fine wiring. In the present invention, it is possible to achieve both dispersibility, dispersion stability, printability, low-temperature firing, and conductivity by using particles having an average particle size in the range of 10 nm to 1 μm. Among them, it is preferable to use particles having an average particle size in the range of 10 nm to 600 nm from the viewpoint of achieving both dispersibility, dispersion stability, printability, low-temperature firing, and conductivity.
In addition, the average particle diameter of the said copper particle can be calculated | required by the method of measuring the magnitude | size of a primary particle directly from an electron micrograph. Specifically, a particle image was measured with a transmission electron micrograph (TEM) (for example, H-7650 manufactured by Hitachi High-Tech), and an average value of the lengths of the longest portions of 30 primary particles selected at random was calculated. The average primary particle size can be obtained.

  What is necessary is just to select the preparation method of the said copper particle from a conventionally well-known method suitably. 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 copper 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 copper-containing compound and a reducing agent are mixed in a solvent in the presence of a complexing agent and an organic protective agent.
In addition to the above method, commercially available copper particles can be used as appropriate.
The shape of the particles is not particularly limited, but is preferably spherical from the viewpoint of dispersibility and printability.

  In the copper particle-dispersed paste of the present invention, the content of the copper particles may be appropriately selected depending on the use, but from the viewpoint of dispersibility, it is 20 to 95% by mass with respect to the total amount of the copper particle-dispersed paste. It is preferable that it is within a range of 25 to 90% by mass.

<Tertiary amine>
The tertiary amine used in the present invention is a tertiary amine having a weight average molecular weight of 3000 or less represented by the following general formula (I).

（Ｒ^１は炭素数１〜２０の脂肪族炭化水素基である。Ｒ^２及びＲ^３はそれぞれ独立に、炭素数１〜２０の脂肪族炭化水素基、又は、−（ＣＨ_２ＣＨ_２Ｏ）_ｎ−（ＣＨ_２ＣＨ（ＣＨ_３）Ｏ）_ｍ−Ｈで表される基（ｍ、ｎは０以上の整数であり、ｍ及びｎの少なくとも１つは１以上）である。）

(R ¹ is an aliphatic hydrocarbon group having 1 to 20 carbon atoms. R ² and R ³ are each independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms or — (CH ₂ CH ₂ O). _n— (CH ₂ CH (CH ₃ ) O) _m —H (m, n is an integer of 0 or more, and at least one of m and n is 1 or more).

In R ¹ , R ² and R ³ , the aliphatic hydrocarbon group having 1 to 20 carbon atoms may be linear, branched or cyclic, and is a saturated or unsaturated aliphatic hydrocarbon group. It may be.
Among these, the aliphatic hydrocarbon group having 1 to 20 carbon atoms is a linear or branched saturated aliphatic hydrocarbon group from the viewpoint of dispersibility, detachability during firing, and decomposability. preferable.
Examples of the aliphatic hydrocarbon group having 1 to 20 carbon atoms include a methyl group, an ethyl group, various propyl groups, various butyl groups, various pentyl groups, various hexyl groups, various octyl groups, various decyl groups, and various dodecyl groups. , Various hexadecyl groups, various octadecyl groups, and the like, but are not limited thereto. Various types mean not only straight chain but also various branched chains. For example, various butyl groups include not only n-butyl group but also sec-butyl group, isobutyl group and t-butyl group. Is willing to do.

A group represented by — (CH ₂ CH ₂ O) _n — (CH ₂ CH (CH ₃ ) O) _m —H in R ² and R ³ (m and n are integers of 0 or more; m and n The upper limit of m and n may be appropriately selected so that the weight average molecular weight of the tertiary amine used is 3000 or less.
When the alkylene oxide chain contains only an ethylene oxide chain or a propylene oxide chain, n or m is preferably 1 to 30, and more preferably 1 to 10.
The alkylene oxide chain may contain both an ethylene oxide chain and a propylene oxide chain. In that case, n + m is preferably 2 to 60, and more preferably 2 to 54.

The tertiary amine represented by the general formula (I) used in the present invention has a weight average molecular weight of 3000 or less, and preferably has a weight average molecular weight of 250 or more from the viewpoint of dispersibility.
In addition, the tertiary amine represented by the general formula (I) used in the present invention has a boiling point of 150 to 300 ° C. from the viewpoint of dispersion stability over time and ease of removal during firing. Is preferred.

Further, when all of R ^1, R ² and R ³ is an aliphatic hydrocarbon group having 1 to 20 carbon atoms, from the viewpoint of improving the conductivity of the sintered film. In the case where all of R ¹ , R ² and R ³ are aliphatic tertiary amines such as aliphatic hydrocarbon groups having 1 to 20 carbon atoms, dispersibility is easily maintained and they are removed from the film during firing. Therefore, it is estimated that the conductivity of the sintered film is improved. When all of R ¹ , R ² and R ³ are aliphatic hydrocarbon groups having 1 to 20 carbon atoms, the weight average molecular weight is preferably 150 to 500, more preferably 150 to 300, from the viewpoint of improving conductivity. It is preferable that

Specific examples in the case where all of R ¹ , R ² and R ³ are aliphatic hydrocarbon groups having 1 to 20 carbon atoms include ethyldimethylamine, propyldimethylamine, dimethylbutylamine, dimethyloctylamine, dimethyldecylamine, dimethyl Examples include dodecylamine, dimethyltetradecylamine, dimethylhexadecylamine, dimethyloctadecylamine, triethylamine, tripropylamine, and tributylamine, but are not limited thereto.

On the other hand, when at least one of R ² and R ³ contains a group represented by — (CH ₂ CH ₂ O) _n — (CH ₂ CH (CH ₃ ) O) _m —H, the dispersion stability is particularly important. The weight average molecular weight is preferably 800 to 3000, more preferably 1000 to 3000. In such a case, since the coating property is good, a highly uniform coating film is obtained, and as a result, it is estimated that the film after baking has high conductivity.

In addition, when at least one of R ² and R ³ contains a group represented by — (CH ₂ CH ₂ O) _n — (CH ₂ CH (CH ₃ ) O) _m —H, the low-temperature sinterability is particularly high. From the viewpoint, the weight average molecular weight is preferably less than 300. In such a case, it is presumed that a film having good conductivity can be obtained because it is easily removed from the film by baking at a low temperature for a short time.

As the tertiary amine used in the present invention, one kind of tertiary amine may be used, or two or more kinds of tertiary amines may be mixed and used.
In the copper particle-dispersed paste of the present invention, the content of the tertiary amine represented by the general formula (I) may be appropriately selected. However, the oxidation resistance, dispersibility, and low-temperature sinterability of the copper particles From the above point, the tertiary amine is preferably 10 parts by mass or less, more preferably 1 part by mass to 10 parts by mass, and more preferably 2 parts by mass to 10 parts by mass with respect to 100 parts by mass of the copper particles. Part.
Moreover, in the copper particle dispersion paste of the present invention, the content of the tertiary amine represented by the general formula (I) is that of the copper particle dispersion paste from the viewpoint of oxidation resistance, dispersibility, and low temperature sinterability. It is preferable that it is 1-15 mass% with respect to the whole quantity, and it is still more preferable that it exists in the range of 1-10 mass%.

<Thermoplastic resin>
The thermoplastic resin used in the present invention is a resin that is softened by heating, imparts a viscosity that makes the copper particle-dispersed paste into a paste, improves application suitability, and is released from the copper particles without being cured during heating. Doing so does not hinder low-temperature sintering.
The thermoplastic resin used in the present invention preferably has a glass transition temperature of 150 ° C. or lower, more preferably 100 ° C. or lower, from the viewpoint of low-temperature sinterability and the conductivity of the sintered film. In addition, the glass transition temperature here is based on the differential scanning calorimetry (DSC) measurement measured according to JIS-K7121.

  Examples of the thermoplastic resin used in the present invention include phenoxy resin, polyvinyl acetal resin, polyvinyl butyral resin, (meth) acrylic resin, polyester resin, vinyl chloride / vinyl acetate copolymer, and the like.

Among the thermoplastic resins used in the present invention, a phenoxy resin is preferably used. The phenoxy resin is a polyhydroxy polyether synthesized from bisphenols and epichlorohydrin. As the phenoxy resin, a part of the hydroxyl group may be alkyl esterified or alkyl etherified.
In the copper particle-dispersed paste according to the present invention, when a phenoxy resin is used, when combined with the specific tertiary amine, the printability is improved particularly among coating suitability, and the pattern resolution is improved when pattern printing is performed. Has the merit of being excellent. The phenoxy resin is presumed to be a resin suitable for imparting thixotropy necessary for printing in addition to the compatibility with the specific tertiary amine.
The suitable phenoxy resin is preferably contained in the total thermoplastic resin in an amount of 50% by mass or more, more preferably 70% by mass or more, and further preferably 90% by mass or more. Especially, it is preferable from the point which is excellent in the resolution of a pattern to use at 100 mass% in all the thermoplastic resins used in this invention.

  The thermoplastic resin used in the present invention preferably has a weight average molecular weight of 10,000 to 100,000, more preferably 30,000 to 60,000, from the viewpoint of excellent printability and low-temperature sinterability. In addition, the weight average molecular weight in this invention can be measured by the gel permeation chromatography (GPC) method (polystyrene conversion).

In the copper particle dispersion paste of the present invention, one type of thermoplastic resin may be used, or two or more types may be used in combination.
In the copper particle-dispersed paste of the present invention, the content of the thermoplastic resin may be appropriately set according to various physical properties such as the viscosity of the paste, but is excellent in dispersibility, printability, low-temperature sinterability, and conductivity. From 100 parts by mass of the copper particles, it is preferably 25 parts by mass or less, more preferably 1 to 25 parts by mass, further preferably 1 to 10 parts by mass, and further 2 to 10 parts by mass. It is preferable that it is a mass part. If content of a thermoplastic resin is more than the said lower limit, it can be made excellent in the dispersibility and dispersion stability of a copper particle dispersion paste, and printability. Moreover, if it is below the said upper limit, it is excellent in low temperature sinterability and the electroconductivity of the film | membrane after baking.

<Solvent>
In the copper particle dispersion paste of the present invention, the solvent is not particularly limited as long as it is an organic solvent that does not react with each component in the copper particle dispersion paste and can dissolve or disperse them. An optimum solvent may be appropriately selected depending on the solid content concentration of the paste.
Among them, as the solvent used in the present invention, ether alcohol acetate solvents and ether solvents are preferably used. For example, methoxybutyl acetate, propylene glycol monomethyl ether acetate, diethylene glycol dimethyl ether, diethylene glycol methyl ethyl ether, propylene glycol monomethyl ether ), Dipropylene glycol monomethyl ether, or a mixture thereof is preferable from the viewpoints of solubility and printability of tertiary amines and thermoplastic resins.

  The content of the solvent in the copper particle dispersion paste of the present invention is not particularly limited as long as it can uniformly dissolve or disperse each component of the copper particle dispersion paste. In the present invention, the solid content in the copper particle-dispersed paste is preferably in the range of 20 to 95% by mass, and more preferably in the range of 25 to 90% by mass. By being the said range, it can be set as the viscosity suitable for printing.

<Other ingredients>
The coated copper particles and the copper particle-dispersed paste 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.

<Paste viscosity>
In the present invention, the viscosity of the paste measured at a shear rate of 1000 (1 / s) at 25 ° C. is 50 mPa · s or more. Among these, from the viewpoint of good printability, the viscosity is preferably 5000 mPa · s or less, and more preferably 100 to 3000 mPa · s.
In the present invention, the viscosity of the paste is measured at a shear rate of 1000 (1 / s) using a viscoelasticity measuring device (for example, product name MCR301, manufactured by Anton Paar Japan). can do.

<Method for producing copper particle dispersion paste>
In this invention, the manufacturing method of a copper particle dispersion | distribution paste should just be a method in which a copper particle can disperse | distribute favorably, and can be suitably selected and used from a conventionally well-known method.
For example, first, copper particles are prepared, the copper particles, the tertiary amine represented by the general formula (I), a thermoplastic resin, a solvent, and other components are mixed as necessary, A copper particle-dispersed paste can be prepared by dispersing using a stirrer or a disperser. Also, for example, after the thermoplastic resin is mixed and stirred in the solvent to prepare a resin solution, the prepared copper particles, tertiary amine, and other components as necessary are mixed into the resin solution. Alternatively, a copper particle-dispersed paste may be prepared by dispersing using a known stirrer or disperser.

  The copper particle-dispersed paste obtained in the present invention is suitably used for conductive substrate applications described later, and is particularly preferably used for conductive pattern printing. The copper particle-dispersed paste obtained in the present invention is not limited to the above-mentioned uses, and can be applied to various metal films. For example, it can be used for mirror surfaces for optical devices, various decoration uses, and the like.

[Method of manufacturing conductive substrate]
The method for producing a conductive substrate according to the present invention includes a copper particle having an average particle size of 10 nm to 1 μm, a tertiary amine having a weight average molecular weight of 3000 or less represented by the general formula (I), a thermoplastic resin, A step of applying a copper particle-dispersed paste containing a solvent and having a viscosity of 50 mPa · s or more measured at a shear rate of 1000 (1 / s) at 25 ° C. on a substrate; and And a step of firing the coating film.

  According to the method for producing a conductive substrate of the present invention, as described above, a copper particle-dispersed paste excellent in oxidation resistance, dispersibility, applicability, and sinterability at low temperature or in a short time is used. A conductive substrate having a highly uniform circuit pattern in which copper particles with suppressed oxidation are present uniformly and densely, having a good pattern accuracy, and having excellent conductivity after sintering. Can be obtained.

Since the step of preparing the copper particle dispersed paste in the method for producing a conductive substrate according to the present invention may be the same as the step of preparing the copper particle dispersed paste described above, the description thereof is omitted here.
Hereinafter, each process of the process of forming a coating film and the process of baking the said coating film is demonstrated in order.
In addition, the manufacturing method of the said electroconductive board | substrate which concerns on this invention may have another process as needed, unless the effect of this invention is impaired.

<The process of apply | coating the coating liquid containing a copper particle dispersion paste on a base material, and forming a coating film>
This step is a step of forming a coating film by applying a copper particle-dispersed paste on a substrate. Hereinafter, details of this process will be described. In addition, since the component of the said copper particle dispersion | distribution paste can be made to be the same as that of the said copper particle dispersion | distribution paste which concerns on this invention, description here is abbreviate | omitted.

(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, an inorganic material such as glass, alumina, or silica can be used, and a polymer material or paper can also be used. Since the metal fine particle dispersion for conductive substrate according to the present invention can obtain a metal film having excellent conductivity even when baked at a temperature lower than conventional, soda lime glass, which has been difficult to apply conventionally, 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 particular, in the present invention, a resin film having a glass transition temperature of 100 ° C. or lower can be used. In addition, the glass transition temperature here is based on the differential scanning calorimetry (DSC) measurement measured according to JISK7121.

  Moreover, in order to control the shape of the pattern when the coating film of the copper particle dispersion paste is formed in a pattern on the substrate surface, or to provide adhesion between the coating film of the copper particle dispersion paste. You may perform the process of. 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 copper particle-dispersed paste is formed in a pattern on the substrate, the wet spread of the paste is suppressed and a high-definition pattern is formed. It is possible. 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 suitably the method of apply | coating the said paste on the said base material from the conventionally well-known methods. Among these, gravure printing, gravure offset printing, reverse offset printing, flexographic printing, and screen printing are preferable from the viewpoint that fine patterning can be performed when the conductive pattern is printed using the copper particle dispersion paste.

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

<Step of baking the coating film>
This step is a step of baking the coating film obtained in the above step to form a metal film.
The firing method can be appropriately selected from conventionally known firing methods. Specific examples of the firing method include, for example, methods such as heating in a firing furnace (oven), infrared heating, firing in a reducing gas atmosphere, firing by laser annealing, microwave heating, and the like.
Since the copper particle-dispersed paste of the present invention can be fired at a low temperature or in a short time, it can be fired at a lower temperature than the conventional method.

In the present invention, in particular, the firing process is a process of firing with surface wave plasma generated by application of microwave energy (hereinafter sometimes referred to as plasma firing), or firing by flash light irradiation. It is preferably one of the processing steps (hereinafter sometimes referred to as flash light baking).
When these methods are used, thermal damage to the substrate can be reduced, and oxidation of the metal during firing can be suppressed. Moreover, since it is baking for a short time, there also exists a merit that productivity is high.

(Plasma firing)
Firing using microwave surface wave plasma is preferably performed in an inert gas atmosphere or a reducing gas atmosphere from the viewpoint of the conductivity of the obtained sintered film.
In particular, in the present invention, the microwave surface wave plasma is preferably generated in a reducing gas atmosphere, and more preferably generated in a hydrogen gas atmosphere. As a result, the insulating oxide present on the surface of the copper particles is reduced and removed, and a conductive pattern with good conductive performance is formed.

  The generation method of the microwave surface wave plasma may be appropriately selected from conventionally known methods. For example, the method described in International Publication No. 2011/040189 pamphlet can be used.

(Flash light firing)
Flash light firing is a method of firing in an extremely short time by irradiation with flash light. Here, in the present invention, flash light refers to light having a relatively short lighting time, and the lighting time is referred to as a pulse width. The light source of the flash 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 them, it is preferable to irradiate light having a continuous wavelength spectrum from ultraviolet to infrared, and specifically, it is preferable to use a xenon flash lamp. 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 copper particle-dispersed paste and its vicinity, and the influence of heat on the substrate is affected. Can be suppressed.
In the present invention, the pulse width of the flash light may be appropriately adjusted, 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 flash light is ^{preferably 0.1J / cm 2 ~100J / cm 2} , 0.5J / cm 2 ~50J / cm 2 is more preferable.
In flash light firing, the number of times of flash light irradiation 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 flash light is irradiated a plurality of times, the irradiation interval of the flash 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 flash light as described above, it is possible to suppress the influence on the base material and to suppress the oxidation of the copper particles, and the specific tertiary amine contained in the copper particle dispersed paste or A conductive substrate that is easy to desorb or decompose thermoplastic resin and has excellent conductivity can be obtained.

Such flash light baking can heat only the coating film of the copper particle-dispersed paste and the vicinity thereof, and the coating film can be fired at a low temperature in a short time. A particle sintered film can be formed. In the flash light firing, the heating temperature and the processing depth can be controlled by appropriately adjusting the pulse width and irradiation energy of the flash 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. Moreover, since baking is possible in a very short time, the oxidation of copper particles can be suppressed and a sintered film having excellent conductivity can be obtained.
The flash 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 flash light baking, heating a coating film.

The thickness of the metal film of the conductive substrate thus obtained may be appropriately adjusted according to the use, but the thickness is usually about 0.01 to 50 μm, and 0.05 to 30 μm. It is preferable that the thickness is 0.1 to 20 μm.
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 copper particle-dispersed paste is applied in a pattern on a substrate, a coating film is formed, and the coating film is baked to form a patterned metal film. The manufacturing method of a conductive substrate may be sufficient.
The conductive substrate obtained by the method for producing a conductive substrate of the present invention has good pattern accuracy and excellent conductivity. 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 having an average particle size of 500 nm)
24 g of cupric oxide, 0.065 g of 3-mercaptopropionic acid as a complexing agent, and 3.8 g of gelatin as a protective colloid are added to 400 ml of pure water, mixed, and the pH of the mixed solution is adjusted with 10% sulfuric acid. After adjusting to 4, the temperature was raised from room temperature to 90 ° C. over 20 minutes. After heating, 80% hydrazine monohydrate was added with stirring and reacted with cupric oxide over 2 hours to obtain copper particles. When the obtained copper particles were observed with a TEM, the average primary particle size was 500 nm.

(Synthesis Example 2 Production of copper particles having an average particle diameter of 50 nm)
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 the temperature rise, a solution prepared by mixing 6.4 g of a 1% mercaptoacetic acid solution and 28 g of 80% hydrazine monohydrate in 150 mL of pure water was added as a complexing agent with stirring. Reaction with dicopper gave copper particles. When the obtained copper particles were observed with a TEM, the average primary particle size was 50 nm.

Example 1
(1) Preparation of Copper Particle Dispersed Paste In an ointment bottle having a volume of 50 mL, 10 g of copper powder having an average particle diameter of 500 nm obtained in Synthesis Example 1, and 3 having a weight average molecular weight of 3000 or less represented by the above general formula (I) 0.4 g of Solsperse 20000 (monodiethylaminoalkyl ether, weight average molecular weight 1000-3000, manufactured by Lubrizol) as a secondary amine, and phenoxy resin (PKHB, manufactured by Inchem, weight average molecular weight 32000, glass transition temperature 84 ° C.) as a thermoplastic resin 4 g, 0.8 g of dipropylene glycol monomethyl ether (DPM) (manufactured by Toho Chemical Co., Ltd.) was added as a solvent, and the mixture was stirred at 2000 rpm × 2 minutes × 3 pass with a vacuum defoaming stirrer (manufactured by Awatori Rentaro Shinky). The mixed solution after stirring was passed five times through a three-roll mill (manufactured by Kodaira Seisakusho) to prepare a paste.
DPM was further added to the prepared paste at a weight ratio of 15%, and the mixture was stirred with a vacuum defoaming stirrer at 2000 rpm × 2 minutes × 3 pass to prepare the copper particle-dispersed paste 1 of Example 1.
(2) Production of conductive substrate by flash light baking After applying the copper particle-dispersed paste obtained in (1) above to a PET film (A4100 manufactured by Toyobo Co., Ltd.) with a wire bar, 100 ° C. using an air-dry oven. Dried for 10 minutes. Using a pulsed xenon lamp device (manufactured by Xenon), the coating film after drying is irradiated with a coating width of 1 inch from the lamp under the condition of a pulse width of 500 μsec and a single irradiation. did. The applied voltage is shown in Table 1.

(Example 2)
(1) Preparation of copper particle-dispersed paste In Example 1, a tertiary amine having a weight average molecular weight of 3000 or less represented by the above general formula (I) was converted from Solsperse 20000 to Amit 102 (POE (2) laurylamine, molecular weight). The copper particle-dispersed paste 2 of Example 2 was prepared in the same manner as in Example 1 except that it was changed to 270 Kao).
POE (m) represents a polyoxyethylene chain (— (CH ₂ CH ₂ O) m—) (m is the number of repetitions of POE).
(2) Production of conductive substrate by flash light firing Except for changing the copper particle-dispersed paste to the copper particle-dispersed paste 2 obtained above, the conductive substrate 2 of Example 2 was prepared in the same manner as Example 1. Manufactured.

(Example 3)
(1) Preparation of copper particle-dispersed paste In Example 1, a tertiary amine having a weight average molecular weight of 3000 or less represented by the general formula (I) was converted from Solsperse 20000 to Nimine L207 (POE (7) laurylamine, molecular weight). The copper particle-dispersed paste 3 of Example 3 was prepared in the same manner as in Example 1 except that it was changed to 493 NOF Corporation.
(2) Production of conductive substrate by flash light baking Except for changing the copper particle dispersion paste to the copper particle dispersion paste 3 obtained above, the conductive substrate 3 of Example 3 was prepared in the same manner as in Example 1. Manufactured.

Example 4
(1) Preparation of copper particle-dispersed paste In Example 1, a tertiary amine having a weight average molecular weight of 3000 or less represented by the above general formula (I) was converted from Solsperse 20000 to Farmin DM2098 (dimethyllaurylamine, molecular weight 213, Kao Corporation). The copper particle-dispersed paste 4 of Example 4 was prepared in the same manner as in Example 1 except that it was changed to).
(2) Production of conductive substrate by flash light baking Except for changing the copper particle-dispersed paste to the copper particle-dispersed paste 4 obtained above, the conductive substrate 4 of Example 4 was prepared in the same manner as Example 1. Manufactured.

(Example 5)
(1) Preparation of copper particle-dispersed paste In Example 1, a tertiary amine having a weight average molecular weight of 3000 or less represented by the above general formula (I) was converted from Solsperse 20000 to Farmin DM0898 (dimethyloctylamine, molecular weight 157, Kao). The copper particle-dispersed paste 5 of Example 5 was prepared in the same manner as Example 1 except that it was changed to).
(2) Production of conductive substrate by flash light firing Except for changing the copper particle-dispersed paste to the copper particle-dispersed paste 5 obtained above, the conductive substrate 5 of Example 5 was changed in the same manner as in Example 1. Manufactured.

(Example 6)
(Preparation of copper particle dispersion paste)
The same procedure as in Example 1 was performed except that the thermoplastic resin was changed from a phenoxy resin to an acrylic resin (Dainal BR105, manufactured by Mitsubishi Rayon, weight average molecular weight 55000, glass transition temperature 50 ° C.) in Example 1. The copper particle dispersion paste 6 of Example 6 was prepared.
(2) Production of conductive substrate by flash light firing Except for changing the copper particle-dispersed paste to the copper particle-dispersed paste 6 obtained above, the conductive substrate 6 of Example 6 was changed in the same manner as Example 1. Manufactured.

(Example 7)
(1) Preparation of copper particle dispersion paste In Example 1, except that the thermoplastic resin was changed from a phenoxy resin to a vinyl acetal resin (manufactured by S-LEC SV12 Sekisui Chemical, weight average molecular weight 30000, glass transition temperature 77 ° C). In the same manner as in Example 1, a copper particle-dispersed paste 7 of Example 7 was prepared.
(2) Production of conductive substrate by flash light baking Except for changing the copper particle dispersion paste to the copper particle dispersion paste 7 obtained above, the conductive substrate 7 of Example 7 was changed in the same manner as in Example 1. Manufactured.

(Example 8)
(1) Preparation of Copper Particle Dispersed Paste In an ointment bottle with a volume of 50 mL, 5 g of copper powder with an average particle diameter of 50 nm obtained in Synthesis Example 2, and a weight average molecular weight represented by the above general formula (I) of 3000 or less 3 Solsperse 20000 (monodiethylaminoalkyl ether, weight average molecular weight 1000-3000, manufactured by Lubrizol Corp.) 0.4 g as a secondary amine, and phenoxy resin (PKHW-34, manufactured by Inchem, weight average molecular weight 32000, glass transition temperature 84 ° C.) 1.18 g and 13.4 g of dipropylene glycol monomethyl ether (DPM) (manufactured by Toho Chemical Co., Ltd.) as a solvent were added, and the mixture was stirred at 2000 rpm × 2 minutes × 3 pass with a vacuum defoaming stirrer (manufactured by Awatori Rentaro Shinki). The mixed solution after stirring was passed five times through a three-roll mill (manufactured by Kodaira Seisakusho) to prepare a copper particle-dispersed paste 8 of Example 8.
(2) Production of conductive substrate by flash light baking Except for changing the copper particle dispersion paste to the copper particle dispersion paste 8 obtained above, the conductive substrate 8 of Example 8 was prepared in the same manner as Example 1. Manufactured.

Example 9
(1) Preparation of copper particle dispersion paste The copper particle dispersion paste 4 of Example 4 was prepared.
(2) Production of conductive substrate by plasma firing After applying copper particle dispersion paste 4 to a polyimide film (Kapton 300H, manufactured by Toray DuPont) with a wire bar, using an air-drying oven at 100 ° C. for 10 minutes. Dried. Using a microwave surface wave plasma processing apparatus (MSP-1500, manufactured by Micro Electronics Co., Ltd.) while introducing hydrogen gas at a gas flow rate of 20 ccm and an introduction pressure of 20 Pa, the microwave output is 550 W. And baked for 180 seconds to obtain a conductive substrate.

(Comparative Example 1)
(1) Preparation of comparative copper particle-dispersed paste In Example 8, in place of the tertiary amine having a weight average molecular weight of 3000 or less represented by the general formula (I), Nopco Spurs 5600 (manufactured by Sannopco polycarboxylic acid dispersant) A comparative copper particle-dispersed paste 1 was prepared in the same manner as in Example 8, except that
When the dispersibility evaluation described later was performed, the comparative copper particle-dispersed paste 1 had poor dispersibility of the copper particles, and the particles settled and separated. Therefore, a conductive substrate using the comparative copper particle dispersion paste 1 was not manufactured.

(Comparative Example 2)
(1) Preparation of Comparative Copper Particle Dispersion Paste In Example 1, phosphanol RS410 (phosphate ester dispersant) was used instead of the tertiary amine having a weight average molecular weight of 3000 or less represented by the general formula (I). Comparative copper particle-dispersed paste 2 was prepared in the same manner as in Example 1 except that Toho Chemical Industries) was used.
(2) Manufacture of Comparative Conductive Substrate by Flash Light Baking Comparative conductivity of Comparative Example 2 was the same as Example 1 except that the copper particle dispersed paste was changed to the comparative copper particle dispersed paste 2 obtained above. A substrate 2 was manufactured.

(Comparative Example 3)
(1) Preparation of comparative copper particle dispersion paste Comparative copper particle dispersion paste 3 was prepared in the same manner as in Example 1 except that the thermoplastic resin was not added.
As a result of evaluation of printability, which will be described later, the comparative copper particle-dispersed paste 3 was found to be dull or streaked and could not be applied uniformly in the surface. Therefore, a conductive substrate using the comparative copper particle dispersion paste 3 was not manufactured.

(Comparative Example 4)
(1) Preparation of Comparative Copper Particle Dispersed Paste In Example 1, a secondary amine distearyllamine (trade name) was used instead of the tertiary amine having a weight average molecular weight of 3000 or less represented by the general formula (I). A comparative copper particle-dispersed paste 4 was prepared in the same manner as in Example 1 except that Farmin D86 (molecular weight 522, Kao) was used.
(2) Production of Comparative Conductive Substrate by Flash Light Baking Comparative conductivity of Comparative Example 4 was the same as Example 1 except that the copper particle dispersed paste was changed to the comparative copper particle dispersed paste 4 obtained above. A substrate 4 was manufactured.

(Comparative Example 5)
(1) Preparation of Comparative Copper Particle Dispersion Paste In Example 1, the same procedure as in Example 1 was used except that Resist Top PL 6220 (manufactured by Gunei Chemical Industry), which is a thermosetting resin, was used instead of the thermoplastic resin. Comparative copper particle dispersion paste 5 was prepared.
(2) Manufacture of Comparative Conductive Substrate by Flash Light Baking Comparative conductivity of Comparative Example 5 was the same as Example 1 except that the copper particle dispersion paste was changed to the comparative copper particle dispersion paste 5 obtained above. A substrate 5 was manufactured.

(Comparative Example 6)
(1) Preparation of Comparative Copper Particle Dispersion Paste In Example 1, instead of a tertiary amine having a weight average molecular weight of 3000 or less represented by the general formula (I), a primary amine, laurylamine (trade name: Farmin 20D). Comparative copper particle-dispersed paste 6 was prepared in the same manner as in Example 1 except that molecular weight 185 manufactured by Kao Corporation was used.
(2) Production of conductive substrate by plasma firing The comparative conductive substrate 6 of Comparative Example 6 was prepared in the same manner as in Example 9 except that the copper particle dispersed paste was changed to the comparative copper particle dispersed paste 6 prepared above. Manufactured.

[Evaluation]
<Viscosity evaluation>
The viscosity of the copper particle dispersion paste was measured using a viscoelasticity measuring device (product name: MCR301, manufactured by Anton Paar Japan) at a temperature of 25 ° C. and a shear rate of 1000 (1 / s). The results are shown in Table 1.

<Dispersibility evaluation>
As an evaluation of the dispersibility of the copper particle-dispersed paste, the copper particle-dispersed pastes obtained in the examples and comparative examples were allowed to stand for 24 hours after preparation and then visually observed to confirm the presence or absence of sedimentation. The results are shown in Table 1.
[Dispersibility evaluation criteria]
A: No separation, no sedimentation of particles is observed Z: Thermoplastic resin is deposited, or particles are sedimented and separated

<Applicability evaluation>
The copper particle dispersion paste obtained in each Example and Comparative Example was applied to a PET film (A4100 manufactured by Toyobo Co., Ltd.) with a wire bar, and then applied to the coating film by visually observing the film quality of the coating film of the copper particle dispersion paste before firing. Evaluation was performed. The results are shown in Table 1.
[Applicability evaluation criteria]
A: There is no blur or streak and it can be applied uniformly.
Z: Scratches and streaks are observed, and it cannot be applied uniformly in the surface.

<Printability evaluation>
The copper particle dispersion paste obtained in each Example and Comparative Example was printed on a PET film (A4100 manufactured by Toyobo Co., Ltd.) using a gravure offset printing machine to obtain a film on which the copper particle dispersion paste was printed. The results are shown in Table 1.
[Printability evaluation criteria]
A: A line with a line width of 30 μm can be resolved B: A line with a line width of 30 μm cannot be resolved, a line width of 100 μm can be resolved Z: A line with a line width of 100 μm cannot be resolved

<Electrical conductivity evaluation>
Conductivity evaluation was performed on the obtained conductive substrate. Using a surface resistance meter ("Loresta GP" manufactured by Dia Instruments, PSP type probe), 4 probes are brought into contact with the metal film of the conductive substrate of each example and comparative example, and the sheet resistance value is obtained by the 4 probe method. It was measured.
Table 1 shows the results of the respective conductive substrates subjected to flash light baking. Moreover, the specific resistance of Example 9 which performed plasma baking was 59.4 microhm * cm, and the specific resistance of the comparative example 6 was 148 microhm * cm.

(Summary of results)
When a high-viscosity copper particle-dispersed paste containing copper particles and a thermoplastic resin is used, by using a tertiary amine having a specific structure having a weight average molecular weight of 3000 or less as a dispersant, the dispersibility of the copper particles, and Examples 1 to 9 have revealed that a film having excellent conductivity can be formed and a film having high conductivity can be formed even when baked at a low temperature or in a short time. Moreover, when the copper particle dispersion paste according to the present invention is used, it is possible to form a circuit pattern with high accuracy because of excellent printability. In particular, it was found that when a phenoxy resin is used as the thermoplastic resin, the printability is improved, and the pattern resolution is excellent when pattern printing is performed.
On the other hand, the copper particle-dispersed paste of Comparative Example 1 using a polycarboxylic acid-based dispersant has a poor dispersibility of the copper particles, and the particles have settled and separated, so that a conductive substrate cannot be produced. . Further, the copper particle dispersion paste of Comparative Example 2 using a phosphate ester dispersant is excellent in dispersibility, coating suitability and printability of copper particles, but has high conductivity when fired at a low temperature or in a short time. Was not obtained. In addition, when the copper particle-dispersed paste of Comparative Example 3 to which no thermoplastic resin was added was evaluated for printability, scumming and streaks were observed and could not be applied uniformly in the surface. Moreover, the copper particle dispersion paste of Comparative Example 4 using a secondary amine having a weight average molecular weight of 3000 or less as a dispersant has poor dispersibility, poor applicability and printability, and is fired at a low temperature or in a short time. The conductivity was inferior. Moreover, the copper particle dispersion paste of Comparative Example 5 using a thermosetting resin instead of the thermoplastic resin is excellent in the dispersibility, coating suitability and printability of the copper particles, but when fired at a low temperature or in a short time. Low conductivity and cracks occurred. Further, the copper particle-dispersed paste of Comparative Example 6 using a primary amine having a weight average molecular weight of 3000 or less as a dispersant was inferior in conductivity when fired at a low temperature or in a short time.

1 Base material 2 Metal film 100 Substrate

Claims (7)

It contains copper particles having an average particle size of 10 nm to 1 μm, a tertiary amine having a weight average molecular weight of 3000 or less represented by the following general formula (I), a thermoplastic resin, and a solvent, and has a shear rate at 25 ° C. 1000 (1 / s) der viscosity of 50 mPa · s or more measured at is, with respect to the copper particles 100 parts by weight, the thermoplastic resin is Ru 1 to 25 parts by mass der, copper particles dispersed paste.

(R ¹ is an aliphatic hydrocarbon group having 1 to 20 carbon atoms. R ² and R ³ are each independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms or — (CH ₂ CH ₂ O). _n— (CH ₂ CH (CH ₃ ) O) _m —H (m, n is an integer of 0 or more, and at least one of m and n is 1 or more).   The copper particle-dispersed paste according to claim 1, wherein the tertiary amine is 1 to 10 parts by mass and the thermoplastic resin is 1 to 25 parts by mass with respect to 100 parts by mass of the copper particles.   The copper particle-dispersed paste according to claim 1 or 2, wherein the thermoplastic resin contains a phenoxy resin. It contains copper particles having an average particle size of 10 nm to 1 μm, a tertiary amine having a weight average molecular weight of 3000 or less represented by the following general formula (I), a thermoplastic resin, and a solvent, and has a shear rate at 25 ° C. 1000 (1 / s) der viscosity of 50 mPa · s or more measured at is, with respect to the copper particles 100 parts by weight, the thermoplastic resin is 1 to 25 parts by mass der Ru copper particles dispersed paste, substrate The manufacturing method of an electroconductive board | substrate which has the process of apply | coating on top and forming a coating film, and the process of baking the said coating film.

(R ¹ is an aliphatic hydrocarbon group having 1 to 20 carbon atoms. R ² and R ³ are each independently an aliphatic hydrocarbon group having 1 to 20 carbon atoms or — (CH ₂ CH ₂ O). _n— (CH ₂ CH (CH ₃ ) O) _m —H (m, n is an integer of 0 or more, and at least one of m and n is 1 or more).   The method for manufacturing a conductive substrate according to claim 4, wherein the baking step is a step of baking by surface wave plasma generated by application of microwave energy or a step of baking by irradiation with flash light.   The method for producing a conductive substrate according to claim 4 or 5, wherein the tertiary amine is 1 to 10 parts by mass and the thermoplastic resin is 1 to 25 parts by mass with respect to 100 parts by mass of the copper particles. .   The method for producing a conductive substrate according to claim 4, wherein the thermoplastic resin contains a phenoxy resin.

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