JP3951722B2 - Conductive laminate and method for producing the same - Google Patents

Description

[0001]
BACKGROUND OF THE INVENTION
The present invention relates to a patterned conductive laminate and a method for manufacturing the same. In particular, the present invention relates to a patterned conductive laminated body such as a printed wiring body used for an electronic device or the like, and a manufacturing method thereof. In particular, the present invention relates to a conductive laminate that can be applied to a wide range of substrates by being formed at a low heat treatment temperature using an inkjet method in a simpler, cheaper and shorter period of time, and a method for manufacturing the same. .
[0002]
[Prior art]
To date, wiring boards used in electronic devices and the like have continued to grow steadily while playing an indispensable role. However, in recent years, with higher performance of electronic devices, especially information communication related devices, and market expansion and fragmentation, further miniaturization of wiring patterns has been demanded, and a variety of products has been accelerated. There is a need for a shorter period. In addition, the proportion of the printed wiring board in the entire electronic device is large, and the cost reduction of the printed wiring board is the most important issue.
[0003]
As a manufacturing method of a laminate having a conductor circuit such as a printed wiring board, an etched foil method is currently used in which an unnecessary portion of a copper foil of a copper-clad laminate is selectively removed by, for example, etching to form a conductor pattern. Although it is a mainstream method, there are other methods such as a method of selectively depositing electroless copper plating or the like on a substrate and a method of printing a conductive paste.
[0004]
However, the etched foil method can cope with further miniaturization of the wiring pattern, but there are many steps such as resist coating and development, as well as copper foil etching, shortening the manufacturing and prototyping period and reducing the cost. It is difficult to make. At present, even in the electroless plating method, a method that does not require a resist coating and developing process has not been put into practical use, and an etching process can be omitted, but as in the etched foil method, manufacturing and prototyping are possible. It is difficult to shorten the period and reduce the cost. In the method of forming a wiring pattern by electroless plating after forming the pattern of the catalyst layer without undergoing the resist coating and development process, which is likely to be put to practical use in the future, the patterning method of the catalyst layer However, a simple and inexpensive method has not been put into practical use at present. In the method of printing the conductive paste, it has been put into practical use by using screen printing, and a manufacturing method using an inkjet method has been proposed. Therefore, it is necessary to go through a baking process at a minimum of 200 ° C., and there are problems such as the narrow selection range of the base material and the influence on the substrate.
[Problems to be solved by the invention]
[0005]
The present invention has been made in view of the above problems, and by providing a layer having ultrafine pores on a substrate, a metal fine particle solution containing no binder can be directly applied by an ink jet method, and the number of steps is reduced. It is an object of the present invention to provide a conductive laminate and a method for producing the same, which is small and inexpensive and does not require a heat treatment step of about 200 ° C. or higher.
[0006]
[Means for Solving the Problems]
According to the first aspect of the present invention, a metal fine particle solution in which metal fine particles are dispersed in a solvent is applied in a pattern by an ink jet method on a substrate having an aggregation promoting layer containing one or more types of inorganic oxide fine particles on the surface. And a heat treatment step of drying the metal fine particle solution formed on the aggregation promoting layer to form a patterned metal fine particle aggregation layer, and applying heat at 200 ° C. or higher during the drying step and after the drying step. It is a manufacturing method of the electroconductive laminated body characterized by not having .
[0007]
Invention of Claim 2 is a manufacturing method of the electroconductive laminated body of Claim 1 whose heat processing temperature in the said drying process is 150 degrees C or less .
[0008]
The invention according to claim 3 is the method for producing a conductive laminate according to claim 1 or 2 , wherein a solvent permeation layer is provided between the aggregation promoting layer and the base material .
[0009]
Invention of Claim 4 provides the film thickness of the said aggregation promotion layer in the range of 10-10000 nm, The manufacturing method of the electroconductive laminated body of any one of Claim 1 thru | or 3 characterized by the above-mentioned. is there.
[0010]
Invention of Claim 5 provides the film thickness of the said solvent osmosis | permeation layer in the range of 1-100 micrometers, It is a manufacturing method of the electroconductive laminated body of any one of Claims 1 thru | or 4 characterized by the above-mentioned. is there.
[0011]
The invention according to claim 6 is characterized in that the fine metal particles are any one of Ag, Al, Cu, Au, Pt, and Pd, or a combination or alloy of two or more kinds thereof. It is a manufacturing method of the conductive laminated body of any one of these .
[0012]
The invention according to claim 7 is the method for producing a conductive laminate according to any one of claims 1 to 6 , wherein the metal fine particle solution does not contain a binder .
[0013]
The invention according to claim 8 has an aggregation promoting layer containing at least one kind of inorganic oxide fine particles on a substrate made of a plastic film or sheet, the metal fine particles are aggregated on the surface of the aggregation promoting layer, and patterning is performed. The conductive laminate is characterized in that a metal fine particle agglomerated layer is formed .
[0014]
The invention according to claim 9 is the conductive laminate according to claim 9 , wherein the total content of the inorganic oxide fine particles in the aggregation promoting layer is 20% by weight or more .
[0015]
The invention according to claim 10 is characterized in that one or more solvent permeation layers containing one or more kinds of inorganic oxide fine particles are provided between the aggregation promoting layer and the base material. It is an electroconductive laminated body as described in above .
[0016]
The eleventh aspect of the present invention is the conductivity according to any one of the eighth to tenth aspects , wherein the total content of the inorganic oxide fine particles in the solvent permeation layer is 20% by weight or more. It is a laminate .
[0017]
In the invention described in claim 12, the kind and composition ratio of the inorganic oxide fine particles contained in the solvent permeation layer is different from the kind and / or composition ratio of the inorganic oxide fine particles contained in the aggregation promoting layer. It is different, It is an electroconductive laminated body of any one of Claims 8 thru | or 11 characterized by the above-mentioned .
[0018]
A thirteenth aspect of the present invention is the conductive laminate according to any one of the eighth to twelfth aspects , wherein the thickness of the aggregation promoting layer is in the range of 10 to 10,000 nm .
[0019]
The invention according to claim 14 is the conductive laminate according to any one of claims 8 to 13 , wherein the solvent permeation layer has a thickness of 1 to 100 μm .
[0020]
The invention according to claim 15 is characterized in that the metal fine particles are any one of Ag, Al, Cu, Au, Pt, Pd, or a combination or alloy of two or more thereof. It is an electroconductive laminated body of any one of these .
[0024]
DETAILED DESCRIPTION OF THE INVENTION
Embodiments of the present invention will be specifically described below.
[0025]
First, as shown in FIG. 1, in the present invention, one or more aggregation promoting layers 2 containing inorganic oxide fine particles are formed on a substrate 4, and wiring pattern-shaped metal fine particles are formed on the aggregation promoting layer 2. This is a conductive laminate in which the aggregate layer 1 is formed. Here, the aggregation promoting layer 2 may be formed on the entire surface or partially.
The aggregation promoting layer of the present invention is a layer for aggregating metal fine particles on or near the aggregation promoting layer by applying a metal fine particle solution.
Moreover, although the said aggregation promotion layer may be provided on a base material, the base material itself may contain the aggregation promotion layer.
[0026]
In this way, by applying a metal fine particle solution not containing a binder on the aggregation promoting layer in a pattern by an ink jet method, pores existing in the inorganic oxide fine particles themselves and gaps between the inorganic oxide fine particles are formed. The solvent selectively permeates mainly into the aggregation promoting layer having pores, and accordingly, aggregation of the metal fine particles is promoted in a portion close to the surface, and an appropriate metal fine particle aggregated layer is formed in a target pattern. Further, since the binder does not need to be burned away by firing, a metal fine particle layer in which metal fine particles are aggregated can be formed at a low heat treatment temperature necessary for drying after applying the metal fine particle solution.
[0027]
Next, it is preferable not only to provide the aggregation promoting layer 3 directly on the substrate 1 but also to provide the solvent permeation layer 2 and further provide the aggregation promoting layer 3. In addition, in FIG. 1, although the structure of the printed wiring body when the solvent permeation layer 2 and the aggregation promotion layer 3 are each provided as one layer is shown, it is not limited to this structure.
The solvent permeation layer of the present invention is a layer for promoting the permeation of the solvent. That is, by providing the solvent permeation layer, it is possible to facilitate the permeation of the solvent as compared with the case where only the aggregation promoting layer is provided.
[0028]
Here, the substrate 1 in the present invention is not particularly limited, and is used as a substrate for printed wiring, such as a paper / phenol resin-based substrate, a paper / epoxy-based substrate, and a paper / polyester-based substrate. Materials, glass / epoxy base materials, glass / polyimide base materials, polyimide, polyetherimide, polysulfone, polyethersulfone, polyetheretherketone, polytetrafluoroethylene, phenol resin, epoxy resin, polyester resin, etc. However, it can be appropriately selected from known glass films or sheets having appropriate mechanical rigidity including various glass substrates. Further, when the base material itself includes an aggregation promoting layer, it is preferably a paper or fiber base material.
[0029]
The metal fine particles can be prepared relatively easily by a number of known techniques represented by the method published by Carey-Lea in 1889 (Am. J. Sci., Vol. 37, pp. 491, 1889). It is.
[0030]
The content of the metal fine particles contained in the metal fine particle solution is preferably 1.0 to 20% by weight, and more preferably 3.0 to 10% by weight.
[0031]
The particle diameter of the metal fine particles used in the metal fine particle solution is preferably a primary particle diameter of 50 nm or less from the viewpoint of fine processing and prevention of nozzle clogging. When the primary particle size is 50 nm or more, the pattern resolution tends to be lowered, and the nozzles are likely to clog.
[0032]
Further, examples of the metal species of the metal fine particles include Ag, Au, Cu, Al, Pd, and the like, but those mainly composed of Ag or Cu are particularly preferable from the viewpoint of conductivity and cost. Moreover, in order to improve chemical stability, these two or more kinds of alloys may be used.
[0033]
As the solvent used for the metal fine particle solution, water is mainly used because of its low viscosity, excellent safety, easy handling, low cost, no odor, etc. Preferably, pure water or ultrapure water that has undergone a purification step such as ion exchange or distillation is preferred.
[0034]
Further, for the purpose of improving the drying property and the fixing property, water having a high volatility such as ethanol and propanol can be added to water as a main solvent in a small amount.
[0035]
In addition to the solvent, the metal fine particle solution includes a dispersing agent such as citric acid used during preparation, a reducing agent that has not been completely washed out, and other additives, but the metal dispersion performance in the solution. Since it may cause deterioration or conductivity deterioration after coating, and conductivity cannot be ensured without performing post-coating baking treatment, it is preferable not to add other additives.
[0036]
As described above, it is desirable not to add an additive to the metal fine particle solution, but a dispersion stabilizer or a wetting agent may be added for the purpose of improving the dispersibility of the metal fine particles or preventing nozzle clogging.
[0037]
As the dispersant for improving the dispersibility, carboxylic acids such as citric acid, stearic acid, lauric acid and oleic acid, and sulfonic acids such as phenyldiazosulfonic acid and dodecylbenzenesulfonic acid are preferably used.
[0038]
Examples of the wetting agent for preventing nozzle clogging include glycerin, ethylene glycol, diethylene glycol, triethylene glycol, propylene glycol, dipropylene glycol, hexylene glycol, 1,4-butanediol, 1,5-pentanediol, 1, High-boiling and low-volatile polyhydric alcohols such as 2,4-butanetriol, 2,2′-thiodiethanol, polyethylene glycol, and polypropylene glycol are used, or monoetherified products, dietherified products, and esterified products thereof such as Ethylene glycol monomethyl ether, ethylene glycol monoethyl ether, ethylene glycol monobutyl ether, diethylene glycol monomethyl ether, diethylene glycol monoethyl ether, diethylene Glycol monobutyl ether and the like, and other N-methyl-2-pyrrolidone, 1,3-dimethylimidazolidinone, monoethanolamine, N, N-dimethylethanolamine, N, N-diethylethanolamine, diethanolamine, N- Nitrogen-containing organic solvents such as n-butyldiethanolamine, triisopropanolamine, and triethanolamine can be used.
[0039]
The solvent permeation layer 3 can achieve the purpose by containing 20% by weight or more of inorganic oxide fine particles, and the higher the content, the more preferable.
[0040]
The inorganic oxide fine particles contained in the solvent permeation layer 3 have almost no gaps between the particles when the particle size is too small. On the other hand, when the particles are too large, the gaps between the particles become large and proper solvent penetration occurs. Since it becomes difficult and appropriate aggregation of the metal fine particles in the aggregation promoting layer is difficult to occur, the particle diameter is preferably in the range of 10 nm to 100 μm, and more preferably in the range of 100 nm to 10 μm.
The structure of the inorganic oxide fine particles is preferably a flake shape, a feather shape, or a shape close to a plate shape.
[0041]
The inorganic oxide species of the inorganic oxide fine particles contained in the solvent permeation layer 3 is not particularly limited, and general silicon oxide fine particles and aluminum oxide fine particles can be used.
[0042]
The other component contained in the solvent permeation layer 3 preferably includes a binder and / or a binder precursor monomer from the viewpoint of film strength. The binder includes a polyester resin, an epoxy resin, a phenol resin, an acrylic resin, and a polyamide. Resins, resins such as polyimide resins used as printed wiring base materials and resins contained in adhesives used for copper-clad boards, but are not limited to this, for example Water-soluble polymers such as polyvinyl alcohol and polyethylene glycol, various thermosetting resins and monomers, photocurable resins and monomers can be used.
[0043]
As the content of the binder and / or binder precursor monomer contained in the solvent permeation layer 3, if it is too large, there will be no gap between the inorganic oxide fine particles, and if it is too small, the coating suitability and the coating strength will be poor. Therefore, the amount is preferably in the range of 1 to 100 parts by weight, more preferably in the range of 5 to 20 parts by weight with respect to 100 parts by weight of the inorganic oxide fine particles.
[0044]
Examples of the method for forming the solvent permeation layer 3 include a method in which a material kneaded in a binder using inorganic oxide fine particles is applied or pasted to a base material, and the inorganic oxide fine particles and the binder are dispersed in a solvent. A method of drying and / or curing the binder, if necessary, after applying the coating liquid to the substrate is also mentioned, and it is preferable to select an appropriate forming method depending on the binder to be used.
[0045]
The thickness of the solvent permeation layer 3 is preferably in the range of 100 nm to 100 μm, more preferably in the range of 1 μm to 50 μm.
[0046]
The aggregation promoting layer 2 can achieve the object by containing 20% by weight or more of inorganic oxide fine particles, and the higher the content, the more preferable.
[0047]
As the inorganic oxide fine particles contained in the aggregation promoting layer 2, when the particle size is too small, there are almost no gaps between the particles, and when the particle size is too large, the gaps between the particles become large and appropriate aggregation of the metal fine particles occurs. Since it becomes difficult, the particle diameter is preferably in the range of 1 nm to 10 μm, more preferably in the range of 10 nm to 1 μm, and further preferably a shape close to a sphere.
[0048]
The inorganic oxide species of the inorganic oxide fine particles contained in the aggregation promoting layer 2 is not particularly limited, and general silicon oxide fine particles and aluminum oxide fine particles can be used.
[0049]
The other component contained in the aggregation promoting layer 2 preferably includes a binder and / or a binder precursor monomer from the viewpoint of film strength. The binder includes a polyester resin, an epoxy resin, a phenol resin, an acrylic resin, and a polyamide. Resins, resins such as polyimide resins used as printed wiring base materials and resins contained in adhesives used for copper-clad boards, but are not limited to this, for example Water-soluble polymers such as polyvinyl alcohol and polyethylene glycol, various thermosetting resins and monomers, photocurable resins and monomers can be used.
[0050]
When the content of the binder and / or binder precursor monomer contained in the aggregation promoting layer 2 is too large, there is no gap between the inorganic oxide fine particles, and when it is too small, the coating suitability and the coating strength are poor. Therefore, the amount is preferably in the range of 1 to 100 parts by weight, more preferably in the range of 5 to 20 parts by weight with respect to 100 parts by weight of the inorganic oxide fine particles.
[0051]
Examples of the method for forming the aggregation promoting layer 2 include a method in which a material kneaded in a binder using inorganic oxide fine particles is applied or pasted to a base material, and the inorganic oxide fine particles and the binder are dispersed in a solvent. A method of drying and / or curing the binder, if necessary, after applying the coating liquid to the substrate is also mentioned, and it is preferable to select an appropriate forming method depending on the binder to be used.
[0052]
The heat treatment temperature of the heat treatment performed during the drying is preferably 150 ° C. or less. Within this range, there is little thermal effect on the substrate, and the range of substrate selection is expanded.
[0053]
The film thickness of the aggregation promoting layer 2 is preferably in the range of 5 nm to 10 μm, more preferably in the range of 10 nm to 2 μm.
[0054]
As a coating method when the solvent permeation layer 3 and the aggregation promoting layer 2 are formed by coating, a usual film forming method such as a spin coating method, an ink jet method, a roll coating method, a spray method, a bar coating method, or a dip method is used. Is possible.
[0055]
As a coating method of the metal fine particle solution that forms an aggregate of patterned metal fine particles, a general-purpose printer can be used, it can be applied at low cost, the coating liquid loss is low, the number of processes is small, and general-purpose Since a wiring pattern can be formed using a computer and general-purpose software, the inkjet method is the most suitable method.
[0056]
A conductive laminate consisting of an aggregation promoting layer and an aggregate of patterned metal fine particles, or a printed wiring body consisting of a solvent permeation layer, an aggregation promoting layer and an aggregate of patterned metal fine particles is formed on one side of a substrate. Alternatively, they may be formed on both surfaces, and may be further laminated via an insulating layer.
[0057]
A method of connecting conductors arranged on both sides when a conductive laminate is formed on both sides of a substrate and a laminate in which a conductive laminate is formed on one side and / or both sides, and conductors of different layers As the connection method, a known method such as connection by a jumper wire in the through hole or embedding of a conductive paste in the through hole can be used.
[0058]
【Example】
A. Preparation of Silver Fine Particle Aqueous Solution A silver fine particle dispersed aqueous solution was prepared by a method (Am. J. Sci., Vol. 37, pp. 491, 1889) published by Carey-Lea in 1889. The average primary particle diameter was about 7 nm by TEM observation. Furthermore, it diluted with distilled water and prepared so that Ag density | concentration might be 7 weight%.
[0059]
B. Preparation of coating solution for forming solvent permeation layer 25 parts by weight of flaky alumina sol aqueous solution (Alumina sol 520 manufactured by Nissan Chemical Industries, 20% by weight of alumina) and 5 parts by weight of 10% by weight aqueous solution of polyvinyl alcohol (PVA217 manufactured by Kuraray) A solution prepared by mixing distilled water at a ratio of 100 parts by weight was prepared by stirring for 30 minutes.
[0060]
C. Preparation of a coating solution for forming an aggregation promoting layer 25 parts by weight of a spherical silica sol aqueous solution (Snowtex Ak, manufactured by Nissan Chemical Industries, silica content 20% by weight) and 5 parts by weight of a 10% by weight aqueous solution of polyvinyl alcohol (PVA217, manufactured by Kuraray) And the solution which mixed distilled water in the ratio of 100 weight part was prepared by stirring for 30 minutes.
[0061]
On a polyethylene terephthalate (PET) film (A4300 manufactured by Toyobo Co., Ltd.), a coating solution for forming a solvent permeation layer was applied by a wire bar coating method so that the film thickness after drying was 10 μm, and dried at 120 ° C. for 1 minute. A solvent permeation layer was formed. On this solvent permeation layer, a coating solution for forming an aggregation promoting layer was applied by wire bar coating so that the film thickness after drying was 0.1 μm, and dried at 120 ° C. for 1 minute to form an aggregation promoting layer. . Further, a silver fine particle aqueous solution was applied on the aggregation promoting layer in the form of a wiring pattern by an ink jet method and then dried at 120 ° C. for 1 minute to prepare a conductive laminate. When observed with an optical microscope, it was confirmed that fine pattern portions of L / S = 40 μm / 40 μm were also formed with high accuracy. Moreover, when the continuity state was confirmed by a continuity test, it was confirmed that there was no short circuit or disconnection.
[0062]
【The invention's effect】
As described above, according to the present invention, a metal fine particle aqueous solution not containing a binder can be directly applied by an ink jet method, and since a step of baking a binder or the like is unnecessary, a heat treatment temperature is low, that is, a substrate is selected. While being able to widen the width and maintaining a fine pattern forming ability, it is possible to provide an electrically conductive laminate and a method for manufacturing the same that are significantly less in number of steps than conventional techniques.
[Brief description of the drawings]
FIG. 1 is a cross-sectional view showing an example of a conductive laminate according to the present invention.
[Explanation of symbols]
DESCRIPTION OF SYMBOLS 1 Aggregation layer of metal fine particle of wiring pattern 2 Aggregation promotion layer 3 Solvent permeation layer 4 Base material 5 Inorganic oxide fine particle

Claims (15)

A step of applying a metal fine particle solution in which metal fine particles are dispersed in a solvent onto a substrate having an aggregation promoting layer containing one or more inorganic oxide fine particles on the surface by an ink jet method ;
A drying step of drying the metal fine particle solution formed on the aggregation promoting layer to form a patterned metal fine particle aggregate layer,
The manufacturing method of the electroconductive laminated body characterized by not having the heat processing process which heats 200 degreeC or more at the time of the said drying process and after a drying process . The method for producing a conductive laminate according to claim 1 , wherein a heat treatment temperature in the drying step is 150 ° C. or less. The method for producing a conductive laminate according to claim 1, further comprising a solvent permeation layer between the aggregation promoting layer and the base material . The method for producing a conductive laminate according to any one of claims 1 to 3, wherein a thickness of the aggregation promoting layer is provided in a range of 10 to 10,000 nm. The method for producing a conductive laminate according to any one of claims 1 to 4, wherein a film thickness of the solvent permeation layer is provided in a range of 1 to 100 µm. The conductive metal according to any one of claims 1 to 5, wherein the metal fine particles are any one of Ag, Al, Cu, Au, Pt, and Pd, or a combination or alloy of two or more kinds thereof. For producing a conductive laminate. The method for producing a conductive laminate according to any one of claims 1 to 6, wherein the metal fine particle solution does not contain a binder. Having an aggregation promoting layer containing at least one kind of inorganic oxide fine particles on a substrate made of a plastic film or sheet ;
A conductive laminate in which metal fine particles are aggregated on the surface of the aggregation promoting layer and a patterned metal fine particle aggregate layer is formed . The conductive laminate according to claim 9, wherein the total content of the inorganic oxide fine particles in the aggregation promoting layer is 20% by weight or more. The conductive laminate according to claim 8 or 9, wherein at least one solvent permeation layer containing at least one kind of inorganic oxide fine particles is provided between the aggregation promoting layer and the substrate . 11. The conductive laminate according to claim 8, wherein the total content of the inorganic oxide fine particles in the solvent permeation layer is 20% by weight or more. Claim 8 wherein the type and composition ratio of inorganic oxide fine particles contained in the layer of solvent permeation layer, wherein different from the type and / or the composition ratio of the inorganic oxide particles contained in the aggregation-promoting layer The electroconductive laminated body of any one of thru | or 11 .   The conductive laminate according to any one of claims 8 to 12, wherein a thickness of the aggregation promoting layer is in a range of 10 to 10,000 nm. 14. The conductive laminate according to claim 8 , wherein the solvent permeation layer has a thickness of 1 to 100 μm.   The metal fine particles are any one of Ag, Al, Cu, Au, Pt, and Pd, or a combination or alloy of two or more thereof. Conductive laminate.

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