JP6232889B2 - Conductive paste, metal thin film, and manufacturing method thereof - Google Patents

Description

  The present invention relates to an electrically conductive paste containing a resin binder having a main chain hydrolyzable as a resin binder, and a metal thin film excellent in conductivity produced by baking a coating film formed using the electrically conductive paste with superheated steam. About.

  In recent years, a technique for forming a desired pattern from a conductive paste containing a metal fine particle dispersion by a printing method such as a screen printing method to form wirings on a circuit board has attracted attention.

  Silver, copper, and nickel are generally used as the metal as the metal fine particles. Silver is not only expensive, but also has poor migration resistance and can become a serious defect depending on the application against the increasing demand for circuit miniaturization. Nickel has poor conductivity. Copper is highly desired as metal fine particles for conductive pastes because it is inexpensive and has good migration resistance. However, copper is easily oxidized, and the resulting oxide has poor conductivity. The conductivity deteriorates due to the heat treatment at the time of producing or storing the conductive copper paste or at the time of forming the copper thin film from the conductive copper paste, and the oxide layer formed on the copper surface during the storage of the copper thin film. Furthermore, the negative effects of copper oxidation also occur when a cover film is laminated to the copper paste circuit to prevent oxidation and insulation.

  A method for treating a conductive copper paste coating film containing copper fine particles in a reducing atmosphere is disclosed. In addition to the well-known heat treatment in nitrogen gas containing 3% of hydrogen gas (Non-patent Document 1), several methods are disclosed. For example, in the microwave surface wave plasma treatment (Patent Document 1), the thickness of the coat that can be treated is limited to 2 mm or less. Further, formic acid gas treatment (Patent Document 2) can be performed at a low temperature of 200 ° C. or lower, but there are concerns about the toxicity of formic acid and the difficulty of treatment with a thick coating film.

  There has been disclosed a photosintering method in which only a coating film containing copper oxide is heated to form a copper coating without irradiating high-energy pulse light and raising the temperature of the substrate. (For example, Patent Document 3) Although this method has an advantage that it can be processed at room temperature in a short time, there is a problem that an irradiation apparatus is expensive and conditions for not damaging the substrate are narrow.

  Furthermore, a method of applying pressure during heating and baking is disclosed. For example, Patent Document 4 and Patent Document 5 disclose a method of forming a conductive film by heat-treating a dispersion of conductive fine particles and then applying pressure while heating. These methods are advantageous in terms of cost and are easy to sinter with silver particles, but in the case of copper particles, the oxidation reaction proceeds easily during heating and pressurization, and the oxide film on the particle surface sinters. Therefore, a film having high conductivity cannot be obtained.

  Patent Document 6 discloses a method of obtaining a copper film by placing a shielding object directly on a coating film containing copper particles and subjecting it to heat and pressure treatment. In this method, the reaction with oxygen in the outside air can be suppressed to some extent, but there is a limit, and if the shield cannot be recycled, a problem of waste arises.

  In Patent Document 7, by applying a conductive paste using copper as a conductive powder to a base material and then performing a superheated steam treatment, it is in a lower oxygen state than in a firing treatment in the atmosphere, and more than air. By using water vapor having a large specific heat capacity, heat-firing can be performed safely and in a short time, and thus a technique has been disclosed in which the specific resistance of a coated metal thin film can be reduced.

  It is known that by reducing the particle size of the metal particles, the firing temperature between the metal particles can be significantly reduced compared to the melting point of the metal bulk. When the average particle size of metal fine particles is about several nanometers to several tens of nanometers, the melting point of the metal particles is significantly lower than that of bulk metal, and the particles are fused at a low temperature. Thus, a conductive thin film is obtained.

  In the conductive paste containing copper fine particles, the copper fine particles are easily oxidized, and the problem is that the tendency becomes more remarkable in the case of copper nanoparticles having a nano particle size. Since the conductivity of the oxidized copper fine particles is remarkably lowered, it is a big problem to suppress oxidation while maintaining dispersibility in order to use as a conductive copper paste.

  When an appropriate resin binder is blended with the conductive resin binder, the resin binder uniformly disperses the conductive metal powder in the dispersion process using the affinity for the metal particles, and improves the conductivity of the formed metal thin film. And the effect of improving the adhesion between the metal thin film and the insulating base. However, the resin binder is insulative and may inhibit the fusion of the conductive metals during firing, thereby inhibiting the conductivity of the metal thin film.

  When forming a conductive pattern using a dispersion containing copper fine particles, in order to ensure good conductivity, the resin binder adsorbed on the copper fine particles is decomposed or detached, and the copper fine particles are sufficiently separated from each other. It is necessary to contact and promote fusion. However, until now, there has not been much consideration regarding the decomposability and detachability of the resin binder, and there is a possibility that the polymer will not sufficiently decompose in the firing process, and the formed wiring may not be able to ensure good conductivity There is.

JP 2010-192841 A International Publication No. 2011/034016 International Publication No. 2006/071419 JP 2005-177710 A JP 2008-124446 A JP 2010-146734 A Japanese Patent No. 485590

Nakayomi et al., “Electronic circuit creation using a new copper nanoparticle paste”, Proceedings of MES 2006 16th Microelectronics Symposium, October 2006, p.51

  The present invention has been made against the background of such prior art problems. That is, an object of the present invention is to provide a conductive metal thin film that can be produced by a baking method using a superheated steam treatment, that can lower the baking temperature, and that can be widely applied to substrates that do not have heat resistance. Is to provide a sex paste.

As a result of intensive studies to achieve the above object, the present inventors have completed the present invention.
That is, the present invention
(1) A conductive paste containing conductive metal powder, a resin binder, and a solvent, wherein the resin binder contains a polymer having a hydrolyzable main chain, and the hydrolyzable main chain The conductive paste for superheated steam treatment, characterized in that the polymer having at least a basic group and a polymer containing an ester bond in the main chain, or a polymer containing an acid group in the side chain and an amide bond in the main chain at least .
(2) The conductive paste according to (1), wherein the conductive metal powder contains at least one selected from copper, copper oxide, and copper complex.
(3) A coating film is formed using the conductive paste according to any one of (1) to (2), and then a metal thin film is obtained by performing a baking treatment at a baking temperature of 200 ° C. or higher with superheated steam. A method for producing a metal thin film.
(4) The metal thin film manufactured by the method as described in said (3).

  Since the conductive paste of the present invention can lower the temperature at which conductivity is exhibited in baking by superheated steam treatment, it can be widely applied to substrates that do not have heat resistance.

  The conductive paste of the present invention contains conductive metal powder, a solvent, and a resin binder whose main chain is hydrolyzable as essential components. The ratio of each component is preferably 400 parts by mass, more preferably 350 parts by mass, and even more preferably 300 parts by mass with respect to 100 parts by mass of the conductive metal powder. Preferably the minimum of a solvent is 50 mass parts, More preferably, it is 30 mass parts, More preferably, it is 20 mass parts. The upper limit of the resin binder whose main chain is hydrolyzable is 10 parts by mass, more preferably 12 parts by mass, and still more preferably 15 parts by mass. The lower limit of the resin binder whose main chain is hydrolyzable is preferably 1 part by mass, more preferably 2 parts by mass, and even more preferably 3 parts by mass. If the proportion of the solvent and the resin binder whose main chain is hydrolyzable is less than this range, there are problems such as failure to disperse well and poor adhesion to the substrate after firing. If it exceeds this, the resin binder whose main chain is hydrolyzable becomes difficult to be thermally decomposed, and there is a problem that conductivity is not exhibited or electrical resistance is increased.

  As the conductive metal powder used in the present invention, either a metal particle fused by heat treatment or a powder not fused can be used. Examples of the metal type of the conductive metal powder used in the present invention include copper, nickel, cobalt, silver, platinum, gold, molybdenum, and titanium, and copper is particularly preferable. Moreover, the metal nanoparticle in this invention contains the metal powder which consists of any one or more of a metal, a metal oxide, a metal complex, and a metal alloy, and consists of copper powder, copper oxide powder, and copper complex powder. A metal powder containing at least one selected from the group is particularly preferred. In addition, a metal powder in which a part or all of the surface is coated with a metal, metal oxide, metal complex or metal alloy, a structure in which different kinds of metals are laminated, or an organic or inorganic material plated with metal may be used. . These metal fine particles may be a commercially available product or can be prepared using a known method.

  The average particle size of the conductive metal powder used in the present invention is preferably 5 μm or less, more preferably 3 μm or less, still more preferably 1 μm or less, and particularly preferably 800 nm or less.

  If the average particle size of the conductive metal powder is larger than 5 μm, the metal particles may settle in the dispersion, or the printability of the fine circuit may be inferior. Although the minimum of an average particle diameter is not specifically limited, It is preferable that it is 10 nm or more. If the thickness is less than 10 nm, it is difficult to obtain a highly conductive metal thin film because a large amount of dispersion medium is required in order to obtain economical restrictions on the conductive metal powder and to obtain a stable dispersion. The conductive metal powder used in the present invention may be used by mixing products having different particle diameters.

  The resin binder whose main chain used for the conductive paste of the present invention is hydrolyzable is not particularly limited as long as it is a polymer whose main chain is hydrolyzable. By using a resin binder having a hydrolyzable main chain as the resin binder, there is an effect of improving the conductivity and lowering the firing temperature for developing the conductivity. Preferred polymers include a polymer containing a basic group in the side chain and an ester bond in the main chain, and a polymer containing an acid group in the side chain and an amide bond in the main chain.

  When the resin binder whose main chain is hydrolyzable used in the conductive paste of the present invention is a polymer containing a basic group and an ester bond in the main chain, the ester bond is hydrolyzed in the presence of water. It is easy to be done. When superheated steam treatment is applied to the coating film of the conductive paste of the present invention, the polymer having a basic group and a main chain having an ester bond undergoes hydrolysis of the ester bond of the main chain due to the catalytic action of the basic group. The chain is cleaved to lower the molecular weight. As a result, it is expected that the resin binder that has covered the surface of the metal fine particles is detached from the surface, the surface of the metal fine particles is exposed, and is easily brought into contact with each other and fused. Specific examples include polyester resins having a tertiary amino group in the side chain, polyester urethane resins, polycarbonate resins, polyester ether resins, and polyesteramide resins.

Examples of the polyester having a tertiary amino group in the side chain include those having a tertiary amino group-containing diol, a tertiary amino group-containing carboxylic acid, and a tertiary amino group-containing carboxylic acid ester as monomers. Specific raw materials include N, N′-bis (carboxymethyl) -2,6-dimethylpiperazine, N- (2-carboxyethyl) -N ′-(carboxymethyl) piperazine, N, N′-bis ( Dicarboxylic acids such as carboxymethyl) -methylamine, N, N′-dimethyl-N, N′-bis (carboxymethyl) -ethylenediamine and the like, their lower alkyl esters, acid halides, N, N′-bis (2 -Hydroxypropyl) -2,5-dimethylpiperazine, N, N'-bis (hydroxyethyl) amine, 2-methyl-2-
Examples thereof include diols such as (N, N′-dimethylaminomethyl) 1,3-propanediol and 2-methyl-2- (N, N′-diisopropylaminomethyl) 1,3-propanediol. In addition to the monomers, aliphatic and aromatic dicarboxylic acids used in normal polyester polymerization, or their lower esters, diols, oxyacids, and the like can be used in combination.

  The diisocyanate component that can be used for polymerization of polyester polyurethane includes known aliphatic, alicyclic or aromatic organic polyisocyanates containing two isocyanate groups in the molecule. Specifically, for example, 4,4'-diphenylmethane diisocyanate, p-phenylene diisocyanate, toluylene diisocyanate, 1,5-naphthylene diisocyanate, xylylene diisocyanate, hexamethidine diisocyanate, isophorone diisocyanate (IPDI), 4, Examples include 4'-dicyclohexylmethane diisocyanate. In particular, isophorone diisocyanate, 4,4'-diphenylmethane diisocyanate or 2,4-tolylene diisocyanate or a mixture containing them as a main component is preferable.

  When the resin binder having a hydrolyzable main chain used in the conductive paste of the present invention is a polymer containing an acidic group in the side chain and an amide bond in the main chain, the amide bond is present in the presence of water. It is easily hydrolyzed. When the coating film of the conductive paste of the present invention is subjected to superheated steam treatment, the amide bond of the main chain is hydrolyzed by the catalytic action of the acidic group, and the main chain is cleaved to reduce the molecular weight. As a result, it is expected that the resin binder that has covered the surface of the metal fine particles is detached from the surface, the surface of the metal fine particles is exposed, and is easily brought into contact with each other and fused. Examples of the polymer include a polyamide resin having a carboxyl group in the side chain, a polyesteramide resin, and a protein such as gelatin (such as gelatin). Specific examples include nylon (Tresin FS-350E5AS, Nagase ChemteX) obtained by graft polymerization of acrylic acid on methylolated nylon, which is alcohol-soluble nylon, and alkali-treated gelatin. Alkali-treated gelatin contains carboxylic acid because acid amide in collagen is hydrolyzed during the gelatin production process to release ammonia and convert it into a carboxyl group.

  As the resin binder, in addition to a polymer having a main chain hydrolyzable, a polymer in which the main chain does not hydrolyze or hardly hydrolyzes can be blended. The ratio of the main chain to the hydrolyzable total resin binder depends on the type and content of the hydrolyzable binding unit, the firing temperature and time with superheated steam, and is not particularly limited. However, when the resin binder is mostly decomposed during firing, depending on the type of conductive metal powder used, the adhesion to the substrate is not good after firing, or the conductive layer obtained after firing is cracked. There is a case. For this reason, the upper limit of the ratio of the polymer whose main chain is hydrolyzable to the total resin binder is preferably 97% by weight or less, more preferably 95% by weight or less, and particularly preferably 90% by weight or less. If the ratio of the total resin binder of the polymer whose main chain is hydrolysable is too small, thermal decomposition and volume shrinkage are reduced at the time of firing, and the contact state between the conductive metal powders is not good. Become. A preferred blending ratio of the polymer having a hydrolyzable main chain is 5% by weight or more, more preferably 10% by weight or more, and particularly preferably 20% by weight or more.

  The solvent used in the conductive paste of the present invention is selected from those that dissolve the binder resin, and may be an organic compound or water. The solvent has a role of adjusting the viscosity of the dispersion in addition to the role of dispersing the metal fine particles in the dispersion. Examples of the organic solvent suitably used as the solvent include alcohol, ether, ketone, ester, aromatic hydrocarbon, amide and the like.

  You may mix | blend a hardening | curing agent with the electrically conductive paste of this invention as needed. Examples of the curing agent that can be used in the present invention include phenol resins, amino resins, isocyanate compounds, and epoxy resins. The amount of the curing agent used is preferably in the range of 1 to 100% by weight of the binder resin.

  When using the metal powder which is easily oxidized in the air such as copper powder as the conductive metal powder in the conductive paste of the present invention, a reducing agent may be contained. In the present invention, the reducing agent means an agent capable of reducing a metal compound such as a metal oxide, hydroxide, or salt to a metal. Examples of the reducing agent include sodium borohydride, lithium borohydride, hydrazine, aldehydes such as formalin and acetaldehyde, carboxylic acids such as sulfites, formic acid, succinic acid, succinic acid and ascorbic acid, or lactones, ethanol, butanol and octanol. Aliphatic monoalcohols such as alicyclic monoalcohols such as terpineol, monoalcohols such as ethylene glycol, propylene glycol, diethylene glycol and dipropylene glycol, polyhydric alcohols such as glycerin and trimethylolpropane, polyethylene Polyethers such as glycol and polypropylene glycol, alkanolamines such as diethanolamine and monoethanolamine, hydroquinone, resorcinol, aminophenol, Dough sugar, or sodium citrate, and the like. Residue of the reducing agent or the reducing agent decomposition product on the metal thin film may cause deterioration of characteristics of the obtained metal thin film. Therefore, it is desirable that the reducing agent is evaporated by superheated steam treatment. For this reason, when a reducing agent is blended in the conductive paste of the present invention, it is particularly desirable to use alcohols or polyhydric alcohols. Specific preferred examples of the reducing agent include terpineol, ethylene glycol, propylene glycol, diethylene glycol, dipropylene glycol, ascorbic acid, and resorcinol.

  As a method for dispersing the conductive metal powder in the paste, a general method for dispersing the powder in a liquid can be used. For example, after mixing a conductive metal powder and a binder resin solution and, if necessary, a mixture of an additional solvent, dispersion may be performed by an ultrasonic method, a mixer method, a three-roll method, a ball mill method, or the like. Of these dispersing means, a plurality of dispersing means can be combined for dispersion. These dispersion treatments may be performed at room temperature, or may be performed by heating in order to reduce the viscosity of the dispersion. If necessary, the reducing agent used may be added at any stage before, during, or after dispersion of the conductive metal powder.

  In order to form a coating film from the conductive paste of the present invention, a general method used when the dispersion is applied or printed on an insulating substrate can be used. For example, a conductive paste is applied or printed by a method such as a screen printing method, a dip coating method, a spray coating method, a spin coating method, a roll coating method, a die coating method, an ink jet method, a relief printing method, an intaglio printing method, and then air-dried. A coating film can be formed by evaporating at least a part of the dispersion medium by heating or decompression. The coating film may be provided on the entire surface of the insulating base material or may be provided partially, or may be a pattern formed product such as a conductive circuit.

  The thickness of the metal thin film of the present invention can be appropriately set according to necessary characteristics such as electric resistance and adhesiveness, and is not particularly limited. The range of the thickness of the conductive thin film that can be formed varies depending on the dispersion composition and the method of coating or printing, but is preferably 0.05 to 40 μm, more preferably 0.1 to 20 μm, and still more preferably 0.2 to 10 μm. It is. In order to obtain a thick metal thin film, it is necessary to increase the thickness of the coating film, which is likely to cause economic deterioration such as an adverse effect due to residual solvent and a need to reduce the coating film forming speed. On the other hand, if the coating film is too thin, the occurrence of pinholes tends to be significant.

  In forming the conductive thin film of the present invention, it is possible to perform overprinting or multilayer printing. Here, overprinting refers to printing the same pattern a number of times, thereby increasing the thickness of the conductive thin film, or conducting with a high aspect ratio (ratio of film thickness to line width). Can be obtained. Multi-layer printing refers to printing different patterns in a superimposed manner, whereby different functions can be exhibited for each layer. Partial overprinting and / or multilayer printing may be performed, and overprinting and multilayer printing may be performed in combination. It is also possible to perform multilayer printing with a thin film different from the conductive thin film of the present invention, for example, an insulating layer.

A metal thin film can be produced by forming a coating film using the conductive paste of the present invention and then performing a heat treatment with superheated steam using the coating film. Superheated steam is high-temperature steam that has obtained energy of, for example, several hundred degrees Celsius by adding secondary energy to a saturated steam gas at 100 degrees Celsius. Superheated steam has a heat capacity approximately four times that of high-temperature air, and it is known that when heated with superheated steam, the substance is heated in a short time.
The coating film formed using the conductive paste of the present invention is preferably subjected to a drying treatment and then fired with superheated steam. A preferable drying temperature is 60 to 120 ° C., and a drying time is 3 to 20 minutes. The drying treatment and baking with superheated steam may be performed continuously or may be performed through other steps. After coating, baking with superheated steam without a drying step is likely to cause bumping, which is not preferable. The drying process and the superheated steam process may be performed continuously or another process may be sandwiched therebetween. Examples of the process sandwiched between the drying process and the superheated steam process include a process of applying a reducing agent to the coating film. In this case, the coating film may or may not contain a reducing agent in advance, and when it is contained, it is any of the same type, different type, and a mixture of the same type and different type. It is also possible. By the treatment of applying a reducing agent to the coating film, effects such as a reduction in volumetric efficiency of the coating film and a reduction in overheat treatment time may be exhibited.

  When methanol, ethanol, ethylene glycol, or propylene glycol is contained in superheated steam, conductivity may be improved. Examples of the method for producing superheated steam containing an alcohol compound include a method of heating a saturated vapor of a solution in which an alcohol compound is dissolved in water, and a method of mixing and heating an alcohol compound and water, and each saturated vapor. The optimum range of the alcohol compound content in the superheated steam varies depending on the type of the compound, but is used in the range of 0.01 to 20% by weight. When the content of the alcohol compound is less than 0.01% by weight, the effect of improving the conductivity is not observed, and when it exceeds 20% by weight, the binder resin may be significantly dissolved or decomposed. A preferred range is from 0.1 to 5% by weight.

  The temperature of the superheated steam used in the present invention is 150 ° C. or higher, particularly 200 ° C. or higher. The upper limit of the temperature is determined by the heat resistance characteristics of the insulating base material and binder resin used, but 400 ° C. or lower is preferable. The heating time is also selected from the amount and characteristics of the object to be processed, but is preferably 10 seconds to 30 minutes. If the temperature of the superheated steam is too low, a conductive layer having a low specific resistance cannot be obtained. If the temperature of the superheated steam is too high, most or all of the binder resin is removed, the adhesion between the conductive thin film and the insulating substrate may be impaired, and the insulating substrate may be deteriorated. In particular, care must be taken when using an insulating substrate made of an organic material.

  When copper powder is used as the conductive metal powder in the conductive paste of the present invention, the surface of the copper powder is easily oxidized in the air, so that the thin film layer can be subjected to rust prevention treatment. As a preferable rust prevention treatment method, a method of providing an adsorption layer of an organic compound or an inorganic compound capable of adsorbing copper on the surface of the conductive thin film layer can be exemplified. Here, when the conductive metal powder contained in the conductive thin film layer contains conductive metal powders that are not fused to each other, the adsorption layer is formed on the surface of each conductive metal powder. Is preferred. Another preferred rust prevention treatment method includes a method of providing a waterproof insulating resin layer on the conductive thin film layer. A method of providing an organic compound or inorganic compound adsorption layer on the surface of the conductive thin film layer and further covering with an insulating resin layer is an example of a preferred embodiment of the present invention.

  Examples of the organic compound or inorganic compound (hereinafter sometimes referred to as a surface treatment agent) that can form an adsorption layer on the surface of the conductive thin film layer in the present invention include nitrogen-containing heterocyclic compounds such as benzotriazole, tolyltriazole, and tetrazole, Examples thereof include sulfur-containing compounds such as mercaptopropionic acid, mercaptoacetic acid, thiophenol and triazinedithiol, amino compounds such as octylamine and isobutylamine, silane coupling agents, titanium coupling agents and chromate treatment agents. The adsorption layer is formed by immersing the conductive thin film in the treatment agent in which the surface treatment agent is dissolved, or by applying the treatment agent to the conductive thin film. When the thickness of the surface treatment agent layer is increased, the conductivity may be lowered or the adhesive processability may be deteriorated. Therefore, the thickness of the surface treatment layer is preferably a thin layer of 0.05 μm or less. Examples of the method for thinning the surface treatment agent layer include reducing the concentration of the treatment liquid and removing excess surface treatment agent with a solvent that dissolves the surface treatment agent.

  Examples of the waterproof insulating resin provided on the conductive thin film layer in the present invention include a polyester resin, an acrylic resin, a polyurethane resin, and a butyral resin. By coating the copper thin film layer with one or more of these resins, the rust prevention effect can be exhibited. The method for coating the conductive thin film layer with a waterproof insulating resin is not particularly limited, but the method is a method in which a resin solution is applied or printed on a copper thin film layer, and then the solvent is stripped off. A method of bonding to the thin film layer can be exemplified as a preferable method. Bonding a polyimide film or a polyester film with an adhesive is an example of a particularly preferred embodiment. The thickness of the insulating resin layer is desirably 1 to 30 μm.

  In order to describe the present invention in more detail, examples are given below, but the present invention is not limited to the examples. In addition, the measured value described in the Example is measured by the following method.

1. Intrinsic Viscosity Measurement Method The reduced viscosity of a dilute toluene solution of a polymer (concentration range: 1 to 10 g / L) was measured using an Ubbelohde viscometer and extrapolated so that the concentration was zero.
2. Method for measuring molecular weight The number average molecular weight in terms of polystyrene was measured by GPC (gel permeation chromatography).
3. Measurement Method of Electric Resistivity (Specific Resistance) The electric resistivity was measured by a four-terminal method using a low resistivity meter (trade name: Loresta CP, manufactured by Mitsubishi Chemical) and a four-point probe (NSCP probe).
4). Evaluation method of adhesion Using 1cm width of cello tape (registered trademark) “CT405AP-15” manufactured by Nichiban Co., Ltd., and sticking 5cm length of the adhesive tape on the metal thin film surface, the metal thin film surface is damaged when peeled off It was judged by visual observation whether it received or not. When some damage such as peeling, floating and cracking was observed on the metal thin film, it was judged as x, and when no damage was found, it was judged as ○.

Example 1
A composition having the following blending ratio was put into a four-necked flask equipped with a stirrer and stirred and heated to obtain polyester 1 according to a conventional method.
Dimethyl terephthalate 50 parts Dimethyl sebacate 30 parts 2-Methyl-2- (N, N'-dimethylaminomethyl) 1,3-propanediol 20 parts Neopentyl glycol 45 parts The composition of the obtained polyester 1 is terephthalic acid / Dimethyl sebacate / 2-methyl-2- (N, N′-dimethylaminomethyl) 1,3-propanediol / neopentyl glycol = 65/35 // 25/75 (molar ratio), intrinsic viscosity is 0 .7.

A composition having the following blending ratio was put into a four-necked flask equipped with a stirrer and stirred and heated to obtain polyester 2 according to a conventional method.
Dimethyl terephthalate 50 parts 2-methyl-2- (N, N′-dimethylaminomethyl) 1,3-propanediol dimethyl isophthalate 38 parts The composition of the obtained polyester 2 is terephthalic acid / 2-methyl-2- (N, N′-dimethylaminomethyl) 1,3-propanediol = 50/50 (molar ratio) and the intrinsic viscosity was 0.6.

A composition having the following blending ratio was put into a four-necked flask equipped with a stirrer and stirred and heated to obtain polyester 3 according to a conventional method.
Dimethyl terephthalate 50 parts Dimethyl isophthalate 20 parts Dimethyl sebacate 30 parts Neopentyl glycol 45 parts Ethylene glycol 55 parts The composition of the obtained polyester 3 is terephthalic acid / isophthalic acid / sebacic acid // ethylene glycol / neopentyl glycol = The number average molecular weight was 15,000 at 50/20/30 // 70/30 (molar ratio).

The composition of the following ratio was disperse | distributed with the 3 roll mill, and the dispersion paste 1 was obtained. Furthermore, it printed so that the thickness after drying might be set to 10 micrometers on a polyimide film with the screen printing method, and it dried with hot air at 80 degreeC for 5 minutes, and obtained metal thin film laminated body 1A.
2.5 parts of 35% by weight n-butyl carbitol acetate solution of polyester 1

Copper fine particles (RCA-16, manufactured by DOWA Electronics Co., Ltd., average particle size 0.8 μm) 20 parts ethyl carbitol acetate 4 parts

Example 2
The composition of the following ratio was disperse | distributed with the 3 roll mill, and the dispersion paste 1 was obtained. Furthermore, it printed so that the thickness after drying might be set to 10 micrometers on a polyimide film with the screen printing method, and it dried with hot air at 80 degreeC for 5 minutes, and obtained metal thin film laminated body 2A.
35% by weight n-butyl carbitol acetate solution of polyester 2 0.8 parts 35% by weight n-butyl carbitol acetate solution of polyester 3 1.7 parts copper fine particles (RCA-16, manufactured by DOWA Electronics Co., Ltd., average particle size) 0.8 μm) 20 parts ethyl carbitol acetate 4 parts

Example 3
The composition of the following ratio was disperse | distributed with the 3 roll mill, and the dispersion paste 2 was obtained. Furthermore, it printed so that the thickness after drying might be set to 10 micrometers on a polyimide film with a screen printing method, and it dried with hot air at 80 degreeC for 5 minutes, and obtained metal thin film laminated body 3A.
2.5 parts of aqueous solution of polyamide 1 (Toresin FS-350E5AS, polyacrylic acid grafted product of methylolated nylon 35% by weight n-butyl carbitol acetate solution)
Copper fine particles (RCA-16, manufactured by DOWA Electronics Co., Ltd., average particle size 0.8 μm) 20 parts
4 parts ethyl carbitol acetate

Example 4
The composition of the following ratio was disperse | distributed with the 3 roll mill, and the dispersion paste 3 was obtained. Furthermore, it printed so that the thickness after drying might be set to 10 micrometers on a polyimide film with the screen printing method, and it dried with hot air at 80 degreeC for 5 minutes, and obtained metal thin film laminated body 4A.
35 wt% n-butyl carbitol acetate solution of alkali-treated gelatin 2.5 parts copper fine particles (RCA-16, manufactured by DOWA Electronics Co., Ltd., average particle size 0.8 μm) 20 parts ethyl carbitol acetate 4 parts

Comparative Example 1
The polyester 1 solution described in Example 1 was dispersed as a polyester 3 solution to obtain a dispersion paste 4. Furthermore, it printed so that the thickness after drying might be set to 10 micrometers on a polyimide film with a screen printing method, and it dried with hot air at 80 degreeC for 5 minutes, and obtained metal thin film laminated body 5A.

Comparative Example 2
A dispersion paste was prepared by using polyamide 1 described in Example 3 as polyamide 2 (Toresin F-30K, 30% by weight n-butyl carbitol acetate solution of methylolated nylon) to obtain dispersion paste 5. Furthermore, it printed so that the thickness after drying might be set to 10 micrometers on a polyimide film with a screen printing method, and it dried with hot air at 80 degreeC for 5 minutes, and obtained metal thin film laminated body 6A.

  Subsequently, five samples of the metal thin film laminates 1A to 6A were each subjected to a firing treatment with superheated steam at 150, 180, 200, 230, and 250 ° C. for 10 minutes, and five kinds of metal thin film laminates having different firing temperatures. 1B-6B were obtained. A steam superheater (“DHF Super-Hi 10” manufactured by Daiichi High-Frequency Industry Co., Ltd.) was used as a superheated steam generator, and the heat treatment was performed in a heat treatment furnace supplying 10 kg / hour of superheated steam. As the firing temperature increases, the specific resistance of the metal thin film laminate decreases. About the metal thin film laminated bodies 1B-6B, the specific resistance in each processing temperature was plotted, and the temperature (conductivity expression baking temperature) which begins to express specific resistance 50micrometer (ohm * cm) and adhesive force were evaluated. The evaluation results are shown in Table 1.

  According to the present invention, in a method for producing a conductive copper thin film by superheated steam treatment, the copper thin film can be formed at a lower temperature than the conventional one and a predetermined specific resistance value can be formed. Moreover, since it has adhesive force with an insulating base material, even if it uses it for a flexible insulating base material, it is hard to generate | occur | produce problems, such as peeling from an insulating base material and a float, with a time-dependent change. The metal thin film of the present invention is useful as a metal thin film forming material such as a metal / resin laminate, an electromagnetic shielding metal thin film, a plating conductive layer, a metal wiring material, a conductive material, and the like. It can be applied to electrodes and the like.

Claims (4)

A conductive paste containing conductive metal powder, a resin binder, and a solvent, wherein the resin binder contains a polymer having a hydrolyzable main chain, and the polymer having a hydrolyzable main chain A conductive paste for superheated steam treatment, which is a polymer containing an ester bond in at least a basic group and a main chain, or a polymer containing an acid group in at least a side chain and an amide bond in the main chain . The conductive paste according to claim 1 , wherein the conductive metal powder contains at least one selected from copper, copper oxide, and copper complex. The manufacturing method of a metal thin film which forms a coating film using the electrically conductive paste in any one of Claims 1-2 , and then performs a baking process by 200 degreeC or more of baking temperature with superheated steam, and obtains a metal thin film. A metal thin film produced by the method according to claim 3 .