阅读说明：本技术 配线基板的制造方法及导电性墨液 (Method for manufacturing wiring board and conductive ink ) 是由 端善久 川上浩 于 2018-06-05 设计创作，主要内容包括：本发明的课题在于提供一种能够简便地制造配线基板的配线基板的制造方法及导电性墨液。本发明的配线基板的制造方法使用转印膜,所述转印膜具有：支撑体；保护层,形成于支撑体的一个表面且能够从支撑体中剥离；及接受层,形成于保护层的表面且接受包含导电性物质及溶剂的导电性墨液中的溶剂,所述配线基板的制造方法具有：配线图案形成工序,通过使用导电性墨液从转印膜中的与形成有支撑体的面相反的一侧的面进行印刷来在转印膜上形成配线图案；粘贴工序,在配线图案形成工序之后,使形成有配线图案的转印膜中的与形成有支撑体的面相反的一侧的面与基板抵接来粘贴转印膜与基板；及剥离工序,在粘贴工序之后,从粘贴于基板的转印膜中剥离支撑体而得到配线基板。(The invention provides a method for manufacturing a wiring substrate and conductive ink, which can simply manufacture the wiring substrate. The method for manufacturing a wiring board of the present invention uses a transfer film having: a support body; a protective layer formed on one surface of the support and peelable from the support; and a receiving layer formed on a surface of the protective layer and receiving a solvent in a conductive ink containing a conductive material and the solvent, the method for manufacturing the wiring board including: a wiring pattern forming step of forming a wiring pattern on a transfer film by printing using a conductive ink from a surface of the transfer film opposite to a surface on which a support is formed; a bonding step of bonding the transfer film and the substrate by bringing a surface of the transfer film on which the wiring pattern is formed, which is opposite to the surface on which the support is formed, into contact with the substrate after the wiring pattern forming step; and a peeling step of peeling the support from the transfer film bonded to the substrate after the bonding step to obtain the wiring substrate.)

1. A method for manufacturing a wiring substrate, using a transfer film having:

a support body;

a protective layer formed on one surface of the support and peelable from the support; and

a receiving layer formed on a surface of the protective layer and receiving the solvent in a conductive ink containing a conductive material and a solvent,

the method for manufacturing the wiring substrate comprises the following steps:

a wiring pattern forming step of forming a wiring pattern on the transfer film by printing using the conductive ink from a surface of the transfer film opposite to the surface on which the support is formed;

a bonding step of bonding the transfer film and the substrate by bringing a surface of the transfer film on which the wiring pattern is formed, which is opposite to a surface on which the support is formed, into contact with the substrate after the wiring pattern forming step; and

and a peeling step of peeling the support from the transfer film bonded to the substrate after the bonding step to obtain a wiring substrate.

2. The method of manufacturing a wiring substrate according to claim 1,

the transfer film also has a solvent permeation layer formed on a surface of the receiving layer and having a gap through which the solvent permeates.

3. The method of manufacturing a wiring substrate according to claim 1 or 2,

the printing is carried out by an inkjet method.

4. The manufacturing method of a wiring substrate according to any one of claims 1 to 3,

the bonding step is performed under heating.

5. The method of manufacturing a wiring substrate according to claim 4,

the heating temperature in the pasting step is 80 ℃ or higher.

6. The manufacturing method of a wiring substrate according to any one of claims 1 to 5,

repeating the following steps to laminate a plurality of wiring patterns on the substrate: after a new transfer film on which the wiring pattern obtained in the wiring pattern forming step is formed is attached to the wiring substrate obtained in the peeling step, the support in the new transfer film is peeled.

7. The manufacturing method of a wiring substrate according to any one of claims 1 to 6,

after the wiring pattern forming step, the wiring pattern is exposed.

8. The manufacturing method of a wiring substrate according to any one of claims 1 to 7,

the conductive material is a metal nanowire having an aspect ratio of 200 or more.

9. The manufacturing method of a wiring substrate according to any one of claims 1 to 8,

the conductive ink further includes a compound represented by formula (I),

[ chemical formula 1]

In the formula (I), X represents a gold atom, a palladium atom or a platinum atom.

10. The method of manufacturing a wiring substrate according to claim 9,

the conductive material is a metal nanowire having an aspect ratio of 200 or more,

the mass ratio of the metal nanowires to the compound represented by the formula (I) is more than 10 and less than 1000.

11. The manufacturing method of a wiring substrate according to any one of claims 1 to 10,

the conductive ink also contains magnetic particles.

12. The manufacturing method of a wiring substrate according to any one of claims 1 to 11,

the conductive ink further contains a coloring material.

13. A conductive ink comprising:

a solvent; a compound represented by the formula (I); and metal nanowires having an aspect ratio of 200 or more,

[ chemical formula 2]

In the formula (I), X represents a gold atom, a palladium atom or a platinum atom.

14. The conductive ink according to claim 13,

the mass ratio of the metal nanowires to the compound represented by the formula (I) is more than 10 and less than 1000.

15. The conductive ink according to claim 13 or 14, further comprising magnetic particles.

16. The conductive ink according to any one of claims 13 to 15, further comprising a colorant.

Technical Field

The present invention relates to a method for manufacturing a wiring board and a conductive ink.

Background

A wiring board having a wiring pattern formed on a substrate is known. Specific examples of such a wiring pattern formation method include: a method of forming a wiring pattern by etching a metal layer provided on a substrate; a method of forming a wiring pattern using a conductive paste or a conductive ink; and a method of forming a wiring pattern by electroless plating.

Among these methods, patent document 1 discloses a method for producing a wiring pattern using a conductive ink (a method for producing a wiring board). Specifically, the following method is shown: after the support film is peeled off from the transfer film in which the support film, the adhesive layer, the conductive layer (wiring pattern) obtained using conductive ink, and the protective layer are sequentially laminated, the conductive layer is bonded to the substrate via the adhesive layer (claim 1, claim 4, and the like).

Prior art documents

Patent document

Patent document 1: international publication No. 2015/068654

Disclosure of Invention

Technical problem to be solved by the invention

In the method for manufacturing a wiring board described in patent document 1, a protective layer for protecting the wiring pattern needs to be formed after the wiring pattern forming step and before the step of bonding the transfer film to the substrate. Therefore, the steps from the wiring pattern forming step to the pasting step cannot be smoothly performed, and the steps become complicated.

Accordingly, an object of the present invention is to provide a method for manufacturing a wiring board, which can easily manufacture a wiring board, and a conductive ink.

Means for solving the technical problem

As a result of intensive studies on the above-described problems, the present inventors have found that a wiring board can be easily manufactured by printing a specific transfer film in which a support, a protective layer, and a receiving layer are laminated in this order from the side opposite to the support using a conductive ink, and using the obtained transfer film, and have reached the present invention.

That is, the present inventors have found that the above problems can be solved by the following configuration.

[1]

A method for manufacturing a wiring substrate, using a transfer film, the transfer film having:

a support body;

a protective layer formed on one surface of the support and peelable from the support; and

a receiving layer formed on the surface of the protective layer and receiving the solvent in the conductive ink containing a conductive material and a solvent,

the method for manufacturing the wiring substrate comprises the following steps:

a wiring pattern forming step of forming a wiring pattern on the transfer film by printing using the conductive ink from a surface of the transfer film opposite to the surface on which the support is formed;

a bonding step of bonding the transfer film and the substrate by bringing a surface of the transfer film on which the wiring pattern is formed, which is opposite to a surface on which the support is formed, into contact with the substrate after the wiring pattern forming step; and

and a peeling step of peeling the support from the transfer film bonded to the substrate to obtain a wiring substrate after the bonding step.

[2]

The method for manufacturing a wiring board according to item [1], wherein the transfer film further includes a solvent permeation layer formed on the surface of the receiving layer and having a gap for allowing the solvent to permeate therethrough.

[3]

The method of manufacturing a wiring board according to item [1] or [2], wherein the printing is performed by an ink jet method.

[4]

The method of manufacturing a wiring board according to any one of [1] to [3], wherein the bonding step is performed under heating.

[5]

The method of manufacturing a wiring board according to item [4], wherein the heating temperature in the pasting step is 80 ℃ or higher.

[6]

The method of manufacturing a wiring substrate according to any one of [1] to [5], wherein the following steps are repeated to laminate a plurality of wiring patterns on the substrate: after a new transfer film on which the wiring pattern obtained in the wiring pattern forming step is formed is attached to the wiring substrate obtained in the peeling step, the support in the new transfer film is peeled.

[7]

The method of manufacturing a wiring board according to any one of [1] to [6], wherein the wiring pattern is exposed after the wiring pattern forming step.

[8]

The method of manufacturing a wiring board according to any one of [1] to [7], wherein the conductive substance is a metal nanowire having an aspect ratio of 200 or more.

[9]

The method for manufacturing a wiring substrate according to any one of [1] to [8], wherein the conductive ink further contains a compound represented by formula (I) described later.

In the formula (I) described later, X represents a gold atom, a palladium atom or a platinum atom.

[10]

The method of manufacturing a wiring board according to item [9], wherein the conductive material is a metal nanowire having an aspect ratio of 200 or more,

the mass ratio of the metal nanowires to the compound represented by the formula (I) is more than 10 and less than 1000.

[11]

The method for manufacturing a wiring substrate according to any one of [1] to [10], wherein the conductive ink further contains magnetic particles.

[12]

The method for manufacturing a wiring substrate according to any one of [1] to [11], wherein the conductive ink further contains a coloring material.

[13]

A conductive ink comprising: a solvent; a compound represented by the formula (I) described later; and metal nanowires having an aspect ratio of 200 or more.

In the formula (I) described later, X represents a gold atom, a palladium atom or a platinum atom.

[14]

The conductive ink according to [13], wherein a mass ratio of the metal nanowire to the compound represented by the formula (I) is more than 10 and less than 1000.

[15]

The conductive ink according to [13] or [14], further comprising magnetic particles.

[16]

The conductive ink according to any one of [13] to [15], further comprising a coloring material.

Effects of the invention

As described below, according to the present invention, it is possible to provide a method for manufacturing a wiring board, which can easily manufacture a wiring board protected by an insulating layer, and a conductive ink. In particular, the present invention can provide a method for manufacturing a wiring board without performing a process such as development, etching, or baking.

Drawings

Fig. 1 is a cross-sectional view schematically showing an example of a transfer film used in the manufacturing method of the present invention.

Fig. 2 is a diagram conceptually showing an example of the structure of the receiving layer in the transfer film used in the manufacturing method of the present invention.

Fig. 3 is a view conceptually showing the structure of a solvent permeation layer in a transfer film used in the manufacturing method of the present invention.

Fig. 4 is a diagram schematically showing an example of the pasting step in the manufacturing method of the present invention.

Fig. 5 is a view schematically showing an example of the peeling step in the manufacturing method of the present invention.

Fig. 6 is a diagram schematically showing an example of the pasting step in the manufacturing method of the present invention.

Fig. 7 is a view schematically showing an example of the peeling step in the production method of the present invention.

Fig. 8 is a diagram schematically showing an example of the pasting step in the manufacturing method of the present invention.

Fig. 9 is a view schematically showing an example of the peeling step in the manufacturing method of the present invention.

Detailed Description

The present invention will be explained below.

The following description of the constituent elements may be based on a representative embodiment of the present invention, but the present invention is not limited to such an embodiment.

In the present invention, the numerical range represented by the term "to" means a range in which the numerical values recited before and after the term "to" are included as the lower limit value and the upper limit value.

In the present invention, "(meth) acrylic acid" represents a general term of "acrylic acid" and "methacrylic acid".

A method for manufacturing a wiring board according to the present invention (hereinafter, also referred to as "present manufacturing method") is a method for manufacturing a wiring board using a transfer film (hereinafter, also referred to as "specific transfer film"), the specific transfer film including: a support body; a protective layer formed on one surface of the support and peelable from the support; and a receiving layer formed on the surface of the protective layer and receiving the solvent in the conductive ink containing the conductive material and the solvent.

The manufacturing method further includes: a wiring pattern forming step of forming a wiring pattern on the specific transfer film by printing using the conductive ink from a surface of the transfer film opposite to the surface on which the support is formed;

a bonding step of bonding the specific transfer film and the substrate by bringing a surface of the specific transfer film on which the wiring pattern is formed, which is opposite to the surface on which the support is formed, into contact with the substrate after the wiring pattern forming step; and

and a peeling step of peeling the support from the specific transfer film bonded to the substrate after the bonding step to obtain a wiring substrate.

In the present manufacturing method, since the specific transfer film on which the protective layer is formed in advance is printed, the step of forming the protective layer is not required between the wiring pattern forming step and the pasting step, and the steps from printing to pasting can be smoothly performed. Thus, according to the manufacturing method, the wiring board can be manufactured by a simple process. In addition, according to the present manufacturing method, it is possible to directly attach wiring to a portion where development, etching, or baking is not possible, for example, a surface of a device or the like.

Hereinafter, the material used in the present manufacturing method will be described in detail, and then each step will be described in detail.

[ specific transfer film ]

The specific transfer film used in the present manufacturing method has: a support body; a protective layer formed on one surface of the support and peelable from the support; and a receiving layer formed on the surface of the protective layer and receiving the solvent in the conductive ink containing the conductive material and the solvent.

The specific transfer film may be formed on the surface of the receiving layer and have a solvent permeation layer having a gap through which the solvent in the conductive ink permeates.

Hereinafter, a specific transfer film will be described in detail with reference to the drawings, taking as an example a case where the specific transfer film has a solvent permeation layer.

Fig. 1 is a cross-sectional view schematically showing an example of a specific transfer film. As shown in fig. 1, the transfer film 10 includes a support 12, a protective layer 14 formed on one surface of the support 12, a receiving layer 16 formed on a surface of the protective layer 14, and a solvent permeation layer 18 formed on a surface of the receiving layer 16.

As will be described in detail later, the transfer film 10 is printed from the solvent permeation layer 18 side using conductive ink, the solvent permeation layer 18 is attached to the substrate P, and then the support 12 is peeled from the protective layer 14, whereby the laminate composed of the solvent permeation layer 18, the receiving layer 16, and the protective layer 14 is transferred to the substrate P to form a wiring pattern on the substrate P.

Therefore, in a state where the laminate of the solvent permeation layer 18, the receiving layer 16, and the protective layer 14 is transferred to the substrate P, the protective layer 14 becomes the surface, and the solvent permeation layer 18 becomes the substrate P side.

(support)

The support 12 supports the protective layer 14, the receiving layer 16, and the solvent permeation layer 18 until the transfer film 10 is attached to the substrate P.

The support 12 may be formed of various known sheet-like materials (films) that can support the protective layer 14, the receiving layer 16, and the solvent permeation layer 18. In particular, when the bonding step (i.e., the heating and bonding) described later is performed under heating, it is preferable to use the support 12 having sufficient heat resistance.

Specific examples of the support 12 include resin films made of various resin materials. Specific examples of the resin material to be the support 12 include polyester resins such as polyethylene terephthalate (pet) and polyethylene naphthalate (pen), polycarbonate resins, acrylic resins, methacrylic resins, and polyimide resins.

The thickness of the support 12 is not particularly limited, and may be set appropriately according to the forming material or the like so as to be able to support the protective layer 14, the receiving layer 16, and the solvent permeation layer 18 before the application step described later is performed, and to be able to be peeled appropriately without breaking or the like after the transfer film 10 is applied to the substrate P.

Specifically, the thickness of the support 12 is preferably 20 to 200. mu.m, and more preferably 50 to 130 μm.

(protective layer)

The protective layer 14 is formed on one surface of the support 12.

The protective layer 14 is a layer that protects the receiving layer 16 after a peeling step described later.

The protective layer 14 preferably comprises a polymer.

The glass transition temperature (Tg) of the polymer that can be contained in the protective layer 14 is preferably 0 ℃ or higher, more preferably 20 ℃ or higher, and further preferably 30 ℃ or higher. When the Tg of the polymer is 0 ℃ or higher, the releasability between the support 12 and the protective layer 14 in a release step described later is further improved.

The upper limit of Tg of the polymer that can be contained in the protective layer 14 is preferably 80 ℃. When the Tg of the polymer is 80 ℃ or less, the (film-forming) protective layer 14 can be formed satisfactorily, and the film-forming temperature can be reduced, whereby the selection range of the support 12 can be expanded.

The Tg of the polymer may be measured by a known method, or may be a value described in various documents, or when a commercially available polymer is used, a value described in a product catalog or the like may be used, or a value calculated from the composition of the polymer may be used. Specific examples of the method for measuring the glass transition temperature include a method of measuring the glass transition temperature by differential scanning calorimetry in accordance with JIS (Japanese Industrial Standards) K7121.

The dissolution parameter (SP value) of the polymer that can be contained in the protective layer 14 is preferably 8.5 (cal/cm)³)^1/2Above, more preferably 9.0 (cal/cm)³)^1/2The above. The SP value of the polymer was set to 8.5 (cal/cm)³)^1/2As described above, since the protective layer 14 can be formed of a polymer having high polarity and strong molecular cohesion, there are advantages such as good scratch resistance of the protective layer 14, high tensile strength of the protective layer 14, and good peelability.

The dissolution parameter of the polymer may be measured by a known method, or may be a value described in various documents, or when a commercially available polymer is used, a value described in a product catalog or the like may be used.

And the SI unit of the dissolution parameter is [ (MPa)^1/2]。[(cal/cm³)^1/2]Can be converted into SI unit [ (MPa) by 2.05 times^1/2]. Namely, "[ (MPa)^1/2]＝[(cal/cm³)^1/2]×2.05”。

When the wiring pattern is formed on the substrate P using the transfer film 10, the solvent permeation layer 18 and the substrate P are bonded to each other in a state where the solvent permeation layer 18 is in contact with the substrate P as described above, and then the support 12 is peeled off.

The lower limit of the thickness of the protective layer 14 is not particularly limited as long as the thickness capable of sufficiently protecting the receiving layer 16 is appropriately set according to the material for forming the protective layer 14.

The thickness of the protective layer 14 is preferably 1 μm or more, more preferably 2 μm or more. The protective layer 14 may have a 1-layer structure or a multilayer structure.

The polymer that can be contained in the protective layer 14 can be any of various known polymers.

Examples thereof include urethane polymers, acrylic polymers, vinyl acetate polymers, vinyl chloride polymers, rubber polymers, styrene polymers, silicone polymers, ester polymers, amide polymers, and copolymers containing a plurality of repeating units constituting these polymers. Among these, urethane polymers are preferable from the viewpoint of more excellent releasability of the support 12.

Further, a commercially available polymer that can be contained in the protective layer 14 may be used.

Specific examples of polymers having a Tg of 0 ℃ or higher among commercially available products include SUPERFLEX 170 (urethane polymer), SUPERFLEX 820 (urethane polymer), SUPERFLEX 830HS (urethane polymer), SUPERFLEX 870 (urethane polymer) manufactured by DKS co., ltd.; VINYBLAN 287 (vinyl chloride-acrylic polymer), VINYBLAN 900 (vinyl chloride-acrylic polymer), VINYBLAN 2684 (acrylic polymer), VINYBLAN 2685 (acrylic polymer), VINYBLAN 2687 (acrylic polymer), VINYBLAN 715S (vinyl chloride-based polymer) manufactured by nissin chemical co., ltd.; SUMIKA chemtex co., SUMIKA FLEX 752HQ (ethylene-vinyl acetate copolymer resin emulsion), SUMIKA FLEX 808HQ (ethylene-vinyl acetate-vinyl chloride copolymer resin emulsion), SUMIKA FLEX 850HQ (ethylene-vinyl acetate-vinyl chloride copolymer resin emulsion), SUMIKA FLEX 830 (ethylene-vinyl acetate-vinyl chloride copolymer resin emulsion); nipol LX433C (styrene butadiene rubber), Nipol LX2507H (styrene butadiene rubber), Nipol LX416 (styrene butadiene rubber), Nipol LX814 (acrylic polymer), Nipol LX855EX1 (acrylic polymer) manufactured by Zeon Corporation; mowinyl 742A (acrylic polymer), Mowinyl 1711 (acrylic polymer), Mowinyl 6520 (acrylic polymer), Mowinyl 7980 (acrylic polymer), Mowinyl 081F (vinyl acetate-ethylene copolymer), Mowinyl 082 (vinyl acetate-ethylene copolymer), and the like, manufactured by Nippon Synthetic Chemical Industry co.

The protective layer 14 may contain 2 or more polymers, and preferably 2 or more polymers each have a Tg of 0 ℃ or more.

When the protective layer 14 contains 2 or more polymers, the transfer film 10 having excellent transferability and scratch resistance of the protective layer can be obtained by expressing the characteristics of each polymer. For example, if a urethane polymer and an ethylene-vinyl acetate-vinyl chloride copolymer polymer are used together, the transfer film 10 having excellent releasability of the support 12 and excellent abrasion resistance of the protective layer 14 can be obtained.

The content of the polymer having a Tg of 0 ℃ or higher is preferably 20% by mass or higher, more preferably 30% by mass or higher, and further preferably 50% by mass or higher, with respect to the total mass of the protective layer 14. When the content of the polymer having a Tg of 0 ℃ or higher is 20 mass% or higher, it is preferable from the viewpoints of favorable peelability between the support 12 and the protective layer 14, favorable scratch resistance of the protective layer 14, favorable bendability (bendability), and the like.

The protective layer 14 may include a surfactant.

When the protective layer 14 contains a surfactant, the peeling property between the support 12 and the protective layer 14 can be improved.

The surfactant can be a known surfactant corresponding to the material for forming the protective layer 14. Specific examples of the surfactant include ethers such as polyoxyethylene nonylphenyl ether, polyoxyethylene octylphenyl ether, polyoxyethylene dodecylphenyl ether, polyoxyethylene oleyl ether, polyoxyethylene lauryl ether, and polyoxyethylene alkyl ether (for example, Emalgen series such as Emalgen 108 and 109P manufactured by Kao Corporation, NIPPON SHOKUBAI CO., LTD. manufactured by SOFTANOL EP-5035, 7085, 9050, PLURONIC L-31, L-34, and L-44 manufactured by ADEKA Corporation);

esters such as polyoxyethylene oleate, polyoxyethylene distearate, sorbitan laurate, sorbitan monostearate, sorbitan monooleate, sorbitan sesquioleate, polyoxyethylene monooleate, and polyoxyethylene stearate;

polyoxyethylene acetylene glycol ether, polyoxyethylene distyrenated phenyl ether, polyoxyethylene tribenzylated phenyl ether, and the like (for example, Surfynol104, 104PG50, 105PG50, 82, 420, 440, 465, 485, OLFINE STG, and the like, manufactured by Nissin Chemical co., ltd.); polyethylene glycol ethers (polyethylene glycol ethers); and nonionic surfactants.

The content of the surfactant is preferably 0.01 to 5% by mass, and more preferably 0.1 to 2% by mass, based on the total mass of the protective layer 14.

The protective layer 14 may contain components other than those described above as necessary, and examples thereof include various additives such as waxes, inorganic pigments, ultraviolet absorbers, and antioxidants.

(receiving layer)

The receiving layer 16 is formed on the surface of the protective layer 14.

The receiving layer 16 is a layer that receives a solvent (water and/or an organic solvent) included in the conductive ink. Specifically, the receiving layer 16 receives the solvent contained in the conductive ink that has permeated the solvent permeation layer 18 and passed mainly through the solvent permeation layer 18. The receiving layer 16 can receive the components (which may be liquid or solid) that have passed through the solvent permeation layer 18, without being limited to the solvent contained in the conductive ink.

Examples of the receiving layer 16 include a layer formed using a polymer that swells upon receiving a solvent, and a layer having voids (micropores) in which microparticles insoluble in a solvent (dispersion medium) contained in the conductive ink are fixed with a binder.

In the example of fig. 1, the case where the transfer film 10 has the solvent permeation layer 18 is described, but when the transfer film 10 does not have the solvent permeation layer 18, the conductive material (and the coloring material used as needed) is held in the receiving layer 16.

Fig. 2 conceptually shows an example of the structure of the receiving layer 16.

The receiving layer 16 shown in fig. 2 is formed by fixing a plurality of receiving particles 20 insoluble in conductive ink with a binder, and receives ink in the gaps between the receiving particles 20.

When the conductive ink contains a coloring material (described later), the particles 20 are preferably made of a material that does not cause aggregation with a fixing agent for fixing the coloring material in the conductive ink between the particles 20, and for example, a material having a non-polarity or a low polarity is used.

Specific examples of the receptor particles 20 include polymer fine particles such as polyolefin, acrylic acid, polystyrene, and polyester, and inorganic fine particles such as calcium carbonate, kaolin, aluminum silicate, calcium silicate, colloidal silica, alumina, and aluminum hydroxide.

Specific examples of the binder for fixing the receptor particles 20 include water-soluble polymers such as gelatin, polyvinyl alcohol, polyvinyl pyrrolidone, alginic acid, water-soluble polyesters, and water-soluble acrylic resins. When the conductive ink contains metal nanowires, polyvinylpyrrolidone that is stable even in aqueous ink and solvent ink is preferable.

When the conductive ink contains a coloring material, the coloring material may be received by the receiving layer 16. In this case, if the receiving layer 16 itself has light scattering ability, light may be scattered and brightness or chroma may be reduced when a wiring pattern is formed (for example, when the wiring board is developed for use in which a backlight is attached to the background). Therefore, the receiving layer 16 is preferably small in light scattering ability and transparent.

In view of this, in order to make the receiving layer 16 transparent by suppressing light scattering and light absorption, it is preferable to use particles that are colorless and have a particle size smaller than the wavelength of visible light, or particles that are colorless and have a refractive index difference of 0.1 or less from the binder that fixes the receiving particles 20. Examples of the combination in which the difference in refractive index between the receiving particles 20 and the binder is 0.1 or less include a combination in which silica is used as the receiving particles 20 and polyvinyl alcohol (pva) is used as the binder.

The thickness of the receptor layer 16 is not particularly limited, and may be appropriately set according to the material for forming the receptor layer 16 such as the receptor particles 20. Specifically, the thickness of the receiving layer 16 is preferably 5 to 50 μm, and more preferably 10 to 40 μm.

The receiving layer 16 may have a 1-layer structure or a multilayer structure.

The ink absorption capacity of the receiving layer 16 is preferably 3 to 40mL/m²More preferably 6 to 30mL/m². The higher the ink absorption capacity of the receiving layer 16, the higher the conductivity becomes.

Here, the ink absorption capacity is a value obtained by the following measurement method. An ink jet recording medium was cut into 10cm square pieces to obtain test pieces, 1mL of diethylene glycol was dropped on the ink-receiving layer of the obtained test pieces, and then excess diethylene glycol that was not completely absorbed was wiped off, and the ink absorption capacity (mL/m) was determined from the difference in mass of the receiving layer before and after dropping and the specific gravity of diethylene glycol²)。

(solvent permeation layer)

A solvent-permeable layer 18 is formed on the surface of the receiving layer.

The solvent permeation layer 18 is a layer having voids that allow the solvent contained in the conductive ink to permeate therethrough.

The solvent permeation layer 18 also has a function of retaining a conductive material (for example, metal nanowires) that can be contained in the conductive ink after the transfer film 10 is printed with the wiring pattern. The solvent-permeable layer 18 may hold a component that cannot pass through the voids among the components contained in the conductive ink.

The solvent permeation layer 18 can function as an adhesive layer (adhesive layer, pressure-sensitive adhesive layer) for adhering the transfer film 10 to the substrate P after the transfer film 10 is printed with the wiring pattern.

The structure of the solvent permeation layer 18 is conceptually illustrated in FIG. 3.

In the solvent-permeated layer 18 shown in fig. 3, the gaps through which the solvent contained in the conductive ink permeates are formed by the gaps L between the plurality of thermoplastic resin particles 26 dispersed throughout the layer. The gaps L formed by the thermoplastic resin particles 26 are continuous in the thickness direction, and thus, a gap penetrating the solvent-permeable layer 18 in the thickness direction is formed.

In the solvent permeation layer 18, the solvent contained in the conductive ink attached to the surface 24 passes through the gap penetrating in the thickness direction, and the solvent contained in the conductive ink is supplied to the receiving layer 16 through the solvent permeation layer 18.

The conductive material contained in the conductive ink adheres to the surface of the thermoplastic resin particles 26 or is held in the solvent-permeated layer 18 by being sandwiched between the voids. In addition, a part of the conductive material may be supplied to the receiving layer 16 through the gap.

In the solvent-permeated layer 18, the particle size, particle distribution, and the like of the thermoplastic resin particles 26 are preferably selected so that the gap L (inter-particle distance) of the thermoplastic resin particles 26 is adjusted to 0.1 μm or more so as not to hinder the penetration of the conductive ink.

In the solvent permeation layer 18, the particle size of the thermoplastic resin particles 26 is preferably set to 0.1 to 10 μm so as not to prevent the conductive ink from permeating and not to diffuse the conductive ink in a direction parallel to the main surface of the transfer film 10.

The thermoplastic resin particles 26 are preferably made of a material having a softening temperature of 40 to 100 ℃ so as not to soften or form a film at an ambient temperature such as room temperature and prevent the penetration of ink from being hindered until the transfer film 10 is bonded to the substrate P.

Examples of such a material include styrene copolymer resins such as styrene, acrylic acid, and butadiene, polyolefin resins, resins containing polymethacrylic acid and derivatives thereof, acrylate resins, polyacrylamide resins, polyester resins, and polyamide resins.

In addition, the solvent permeation layer 18 preferably contains tackifier particles 28 (tackifier resin particles 28) dispersed therein for improving the adhesion to the substrate P.

As a material constituting the tackifier particles 28, rosin ester, alicyclic resin, phenol resin, chlorinated polyolefin resin, urethane resin, or the like can be used. Alternatively, the tackifier may be contained in the thermoplastic resin particles 26, instead of being dispersed as particles in the solvent-permeable layer 18. For example, when heat bonding is performed, if the tackifier enters the thermoplastic resin during heat bonding, the adhesion with the substrate P can be enhanced.

The solvent permeation layer 18 is located closer to the substrate P than the receiving layer 16 on which the wiring substrate is mounted in a state where the transfer film 10 is transferred to the substrate P. That is, when the conductivity of the wiring substrate formed on the substrate P by the transfer film 10 is confirmed, the solvent permeation layer 18 serves as a base of the receiving layer 16 for retaining an image.

Therefore, the solvent permeation layer 18 may be formed as a white layer or a light scattering layer by mixing and adding a white inorganic pigment, organic resin fine particles including a white polycarbonate and/or a (meth) acrylic resin, or light scattering particles, for example, to the solvent permeation layer 18. This is preferable when the wiring board (wiring pattern) to which the transfer film 10 is transferred is to be clearly reflected, because the wiring pattern having excellent visibility and clarity can be obtained.

The thickness of the solvent permeation layer 18 is not particularly limited as long as the thickness that can be bonded to the substrate P with sufficient adhesion force is appropriately set according to the material or the like for forming the solvent permeation layer 18 such as the thermoplastic resin particles 26. Specifically, the thickness of the solvent permeation layer 18 is preferably 0.5 to 5 μm, more preferably 0.8 to 3 μm.

The solvent permeation layer 18 may have a 1-layer structure or a multi-layer structure.

(method of manufacturing transfer film)

The transfer film 10 can be produced by a known method corresponding to a material for forming each layer. An example of the method for manufacturing the transfer film 10 is described below.

First, a resin film to be the support 12 is prepared.

On the other hand, a coating liquid for forming the protective layer 14 is prepared by dissolving or dispersing a compound (for example, a polymer having a Tg of 0 ℃ or higher) or the like to be the protective layer 14 in ion-exchanged water or the like.

Then, a coating liquid for forming the receiving layer 16 is prepared by dissolving or dispersing the ink-receiving particles 20 (for example, silica particles) and a compound to be the receiving layer 16 such as a binder in ion-exchanged water or the like.

A coating liquid for forming the solvent-permeable layer 18 is prepared by dissolving or dispersing the thermoplastic resin particles 26 (for example, polyethylene particles) and a compound that becomes the solvent-permeable layer 18, such as a binder, in ion-exchanged water or the like.

Then, first, a coating liquid for forming the protective layer 14 is applied to the surface of the support 12 and dried, thereby forming the protective layer 14. The coating method of the coating liquid may be performed by a known method such as a bar coating method, a die coating method, and a dip coating (dip coating). The coating liquid may be dried by a known method corresponding to the coating liquid, such as drying by heating with warm air or a heater. In this regard, the receiving layer 16 and the solvent-permeable layer 18 are also the same.

Next, a coating liquid for forming the receptor layer 16 is applied to the surface of the formed protective layer 14 and dried, thereby forming the receptor layer 16.

Further, a coating liquid for forming the solvent permeation layer 18 is applied to the surface of the formed receptor layer 16 and dried, thereby forming the solvent permeation layer 18. Thus, the transfer film 10 is obtained.

[ base plate ]

The substrate P is not particularly limited, and various known products such as resin molded products (for example, films) such as various sensors such as cards and wearable circuit boards, metal products such as silicon wafers, and products formed of paper such as coated cardboard and corrugated cardboard can be used.

Examples of the material constituting the resin molded article include polyester resins such as polyethylene terephthalate (pet) and polyethylene naphthalate (pen), polycarbonate resins, acrylic resins, methacrylic resins, polyimide resins, and the like.

In the substrate P, large three-dimensional objects, films and papers having low heat resistance are easily affected by the processes such as development, etching and baking, and therefore, may be difficult to use in the conventional method. Therefore, in the present manufacturing method, a large three-dimensional object, a film having low heat resistance, paper, or the like can be preferably used as the substrate P.

[ conductive ink ]

The conductive ink of the present invention contains a conductive material and a solvent. Conductivity means electrical conduction.

(conductive material)

The conductive substance is not particularly limited as long as it has conductivity, and examples thereof include metals such as copper, chromium, lead, nickel, gold, platinum, palladium, silver, tin, and zinc, and alloys of these metals.

The conductive material may be in any shape such as a spherical shape or a linear shape, but from the viewpoint of more excellent conductivity, a linear shape is preferable, and a linear shape made of a metal or an alloy of metals (that is, a metal nanowire) is preferable.

The metal nanowires preferably comprise silver and metals other than silver. The metal other than silver is preferably a metal more noble than silver, more preferably gold, platinum, or palladium, and still more preferably gold.

The metal other than silver may be alloyed with silver or may be coated with silver nanowires to be cores, but the coated silver nanowires are preferable. When the silver nanowire is coated, the metal other than silver does not necessarily have to coat the entire surface of the silver nanowire that becomes the core, as long as a part thereof is coated.

Since the ionization energy of a metal more noble than silver is higher than that of silver, silver nanowires are alloyed with the metal or the surface is plated to be introduced. This can improve the oxidation resistance of the metal nanowire. Further, if a small amount (specifically, preferably 0.5 to 10 parts by mass, more preferably 1 to 5 parts by mass, per 100 parts by mass of silver) of a metal that is more noble than silver is contained in the silver nanowires, the heat resistance of the nanowires can be improved.

The content of each metal atom in the metal nanowire can be measured, for example, by dissolving the metal nanowire with an acid or the like and then using an ICP (high frequency inductively coupled plasma) emission spectrometer.

The shape of the metal nanowire is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include any shape such as a cylindrical shape, a rectangular parallelepiped shape, and a columnar shape having a polygonal cross section.

From the viewpoint of easy conduction and reduction in the resistance of the wiring pattern, the average length of the long axis of the metal nanowire is preferably 1 μm or more, more preferably 5 μm or more, and still more preferably 10 μm or more. From the viewpoint of dispersion stability and ejection stability of inkjet printing, the upper limit of the average length of the long axis of the metal nanowire is 1000 μm or less.

The average length of the minor axis of the metal nanowire is preferably 3nm or more and less than 200nm, more preferably 5 to 100 nm. The metal nanowire has excellent heat resistance if the average length of the minor axis is 3nm or more, and has a sufficient surface area if the average length of the minor axis is less than 200nm, so that the conductivity of the metal nanowire is further improved.

The average length of the long axis of the metal nanowires is a value obtained by arbitrarily selecting 200 metal nanowires from a Transmission Electron Microscope (TEM) image including a plurality of metal nanowires observed by a TEM and arithmetically averaging the lengths of the long axes of the metal nanowires. Similarly, the average length of the short axis of the metal nanowire is a value obtained by arbitrarily selecting 200 metal nanowires from a TEM image including a plurality of metal nanowires and arithmetically averaging the lengths of the short axes of the metal nanowires.

The aspect ratio of the metal nanowire is preferably 200 or more. When the aspect ratio of the metal nanowire is 200 or more, the wiring pattern is more easily conducted when the wiring pattern is printed by an ink-jet method, and as a result, the resistance can be further reduced.

The upper limit of the aspect ratio of the metal nanowire is usually 10000 or less.

In addition, the aspect ratio of the metal nanowire refers to a ratio of the average length of the major axis to the average length of the minor axis in the metal nanowire.

The aspect ratio of the metal nanowire and the content of the metal other than silver can be controlled by appropriately selecting the concentrations of the metal salt, the inorganic salt, and the organic acid (or the salt thereof), the kind of the solvent used in forming the particle, the concentration of the reducing agent, the addition rate of each component, the temperature, and the like in the method for producing the metal nanowire.

Specific examples of the method for producing a metal nanowire include the methods described in paragraphs 0019 to 0024 of Japanese patent application laid-open No. 2011-149092.

The content of the conductive material is preferably 0.1 to 20% by mass, and more preferably 0.3 to 15% by mass, based on the total mass of the conductive ink.

Conventionally, the metal nanowires preferably have the following heat resistance as heat resistance.

Specifically, when wiring patterns (wiring boards) formed using metal nanowires are used for various device applications, heat resistance is generally required to withstand a step of bonding (faceting) using a thermoplastic resin of 150 ℃ or higher and a solder reflow step of a wiring portion of 220 ℃ or higher in the manufacturing process of various devices. From the viewpoint of providing a highly reliable transparent conductor to the production process, the heat-resistant layer preferably has heat resistance to heating at 240 ℃ for 30 minutes, and more preferably has heat resistance to heating at 240 ℃ for 60 minutes.

If heating is performed, the silver nanowires are deformed to be approximately spherical in order to minimize the surface area. Specifically, the wire may be broken, the chips may be deformed into a nearly spherical shape, and if the chips are exposed to heat and a high humidity environment for a long time, the resistance value may increase, and eventually conduction may be disabled.

In order to solve such a problem, even when silver nanowires are used, since a strong insulating layer (protective layer) can be formed on the surface of the wiring board after the peeling step by using both the pasting step and the peeling step in the present manufacturing method, the variation in the resistance value can be suppressed even when the wiring board is exposed to an environment of 85 ℃ and 85% RH (relative humidity) for 120 hours.

(solvent)

The solvent has a function of adjusting the viscosity of the conductive ink by dispersing or dissolving components contained in the conductive ink, for example.

Examples of the solvent include water and an organic solvent. Either one of the water and the organic solvent may be used, or both of them may be used. When water and an organic solvent are used together, it is preferable to use an organic solvent mixed with water.

The organic solvent is not limited to this, but an alcohol solvent having a normal boiling point of 50 to 250 ℃ is preferable, and an alcohol solvent having a normal boiling point of 55 to 200 ℃ is more preferable. When an alcohol solvent having a normal boiling point of 50 to 250 ℃ is used, there are advantages in that ejection stability is improved and the drying rate of the conductive ink is improved when printing is performed by an inkjet method.

The alcohol compound is not particularly limited and can be appropriately selected according to the purpose, and examples thereof include methanol, ethanol, ethylene glycol, diethylene glycol, triethylene glycol, polyethylene glycol 200, polyethylene glycol 300, glycerin, propylene glycol, dipropylene glycol, 1, 3-propanediol, 1, 2-butanediol, 1, 4-butanediol, 1, 5-pentanediol, I-ethoxy-2-propanol, ethanolamine, diethanolamine, 2- (2-aminoethoxy) ethanol, and 2-dimethylaminoisopropanol, with ethanol and ethylene glycol being preferred. The alcohol compound may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The organic solvent preferably contains an organic solvent having a boiling point of 100 ℃ or higher among the organic solvents described above, from the viewpoint of suppressing ejection failure due to drying of the conductive ink in the head of the inkjet recording apparatus. The content of the organic solvent having a boiling point of more than 100 ℃ is preferably 5 to 30% by mass, more preferably 8 to 25% by mass, based on the total mass of the conductive ink.

(Compound represented by the formula (I))

The conductive ink preferably contains a compound represented by the following formula (I) (hereinafter, also referred to as "compound (I)"). The compound (I) is also known as noble metal thioglucose. When the conductive ink contains the compound (I), migration of the wiring pattern can be suppressed.

In the present invention, migration (electromigration) means that a conductive substance such as a metal is ionized and ions are moved (migrated).

[ chemical formula 1]

In the formula (I), X represents a gold atom, a palladium atom or a platinum atom, and a gold atom is preferable from the viewpoint of achieving both the stability and the conductivity of the wiring pattern.

Among the above conductive materials, metal nanowires (particularly silver nanowires) are very useful because they exhibit conductivity even when a wiring pattern is formed at room temperature. However, since metals generally have a surface oxidation property, migration is likely to occur as the surface area of the nano-region increases, and as a result, the wiring pattern may be broken.

In order to solve such a problem, the compound (I) can suppress migration, and therefore can suppress occurrence of disconnection or the like of the wiring pattern. Therefore, the conductive ink preferably uses the metal nanowire and the compound (I) at the same time.

The content of the compound (I) is preferably 0.005 to 0.5% by mass, more preferably 0.01 to 0.3% by mass, and still more preferably 0.02 to 0.1% by mass, based on the total mass of the conductive ink. When the content of the compound (I) is within the above range, the above effects are further exhibited.

When the conductive material contained in the conductive ink is a metal nanowire, the mass ratio of the metal nanowire to the compound (I) is preferably more than 10 and less than 1000, more preferably more than 20 and less than 150, and further preferably more than 50 and less than 120. When the mass ratio exceeds 10, the action of sulfur atoms in the molecular skeleton of the compound (I) can be suppressed, and thus the conductivity of the wiring pattern can be further improved. If the mass ratio is less than 1000, the durability of the wiring board is further improved.

(magnetic particle)

The conductive ink may contain magnetic particles. When a magnetic field is applied to the head at the time of printing the wiring pattern by the ink jet method, the magnetic particles are aligned along the magnetic field. Accordingly, the conductive substance (particularly, the metal nanowires) is also aligned along the magnetic field, and therefore the conductive substance is less likely to block the ejection nozzle. As a result, the ejection stability of the conductive ink is improved.

Specific examples of the magnetic particles include magnetite (Fe)₃O₄) Maghemite (gamma-Fe)₂O₃)1 or more kinds of iron oxide particles.

The content of the magnetic particles is preferably 0.1 to 20% by mass, more preferably 0.5 to 10% by mass, and still more preferably 1 to 5% by mass, based on the total mass of the conductive ink.

The magnetic particles may be added to the conductive ink in the form of a magnetic fluid in which the magnetic particles are dispersed in a liquid medium.

(coloring material)

The conductive ink may contain a coloring material. This allows the wiring pattern to be in a color corresponding to the substrate or to be drawn using the wiring pattern.

The coloring material may be a dye, a pigment, or the like, and is preferably a dye in view of being dissolved in a solvent and easily held by the receiving layer. The type of the dye and the pigment is not particularly limited, and known materials can be used.

The content of the coloring material is preferably 0.02 to 10% by mass, more preferably 0.1 to 5% by mass, and still more preferably 0.2 to 3% by mass, based on the total mass of the conductive ink.

The content of the coloring material is preferably 0.1 to 100 parts by mass, more preferably 1 to 50 parts by mass, and still more preferably 2 to 20 parts by mass, per 100 parts by mass of the conductive material in the conductive ink.

(other Components)

The conductive ink may contain other components than the above components to such an extent that the conductivity is not affected. Examples of the other components include polymerizable compounds, vulcanization inhibitors, corrosion inhibitors, surfactants, antioxidants, viscosity modifiers, and preservatives.

Among these, the conductive ink preferably contains a corrosion inhibitor. By containing the corrosion inhibitor, a higher rust prevention effect may be exhibited.

As the corrosion inhibitor, azoles are preferred, and specific examples thereof include benzotriazole, tolyltriazole, mercaptobenzothiazole, mercaptobenzotriazole, mercaptobenzothiazole, (2-benzothiazolylthio) acetic acid, 3- (2-benzothiazolylthio) propionic acid, and alkali metal salts, ammonium salts and amine salts thereof. The corrosion inhibitor may be used alone in 1 kind, or may be used in combination in 2 or more kinds.

The corrosion inhibitor may be added after being dissolved in a solvent suitable for the conductive ink.

When the conductive ink contains the corrosion inhibitor and the compound (I), the mass ratio of the corrosion inhibitor to the compound (I) is preferably 0.01 or less.

From the viewpoint of minimizing the decrease in conductivity due to metal corrosion, the conductive ink preferably does not contain inorganic ions such as alkali metal ions, alkaline earth metal ions, and halide ions.

(physical Properties of conductive ink)

The conductivity of the conductive ink is preferably 1mS/cm or less, more preferably 0.1mS/cm or less, and still more preferably 0.05mS/cm or less. The conductivity can be measured using a portable conductivity meter CM-31P (trade name, DKK-TOA CORPORATION).

The viscosity of the conductive ink at 25 ℃ is preferably 0.5 to 100 mPas, more preferably 1 to 50 mPas. The viscosity can be measured using VISCOMATE VM-1G-L (trade name, Tokyo garsu Kikai co., Ltd. (TGK)).

[ method for manufacturing Wiring Board ]

An example of the present manufacturing method will be described in detail with reference to fig. 1 to 5.

First, conductive ink is ejected from a nozzle of a head of an inkjet recording apparatus and is ejected onto the surface 24 of the solvent permeation layer 18 of the transfer film 10. The solvent contained in the ejected conductive ink passes through the gaps of the thermoplastic resin particles 26, thereby penetrating into the solvent-permeable layer 18 and being retained by the receiving layer 16. On the other hand, the conductive material (for example, metal nanowires) contained in the ejected conductive ink adheres to the surface of the thermoplastic resin particles 26 or is fixed by being sandwiched between the thermoplastic resin particles 26. Thus, the wiring pattern is held by the solvent permeation layer 18 (wiring pattern forming step).

Further, as a method of printing, an ink jet method is exemplified from the viewpoint of being able to appropriately cope with on-demand printing (on-demand printing), but a known printing method such as a screen printing method may be used.

After the wiring pattern forming step, the transfer film 10 having the wiring pattern formed thereon and the substrate P are laminated by bringing the solvent permeation layer 18 of the transfer film 10 into contact with the substrate P. Next, the transfer film 10 (solvent permeation layer 18) and the substrate P are heated (heat-bonded ) by heating from the support 12 side as necessary while pressing the transfer film 10 and the substrate P as necessary (bonding step, see fig. 4).

Here, the heating temperature in the heat bonding is preferably 80 ℃ or higher, more preferably 90 ℃ or higher, and further preferably 100 ℃ or higher. By heating and bonding at a temperature of 80 ℃ or higher, the adhesion between the transfer film 10 and the substrate P is further improved.

The lower limit of the heating temperature is preferably 150 ℃ or less, more preferably 140 ℃ or less, and still more preferably 130 ℃ or less. In particular, if the temperature is 130 ℃ or lower, there is an advantage that when the substrate P is a PET film, precipitation of low molecular weight substances (for example, oligomers) present in PET can be suppressed, or deformation of the substrate P can be suppressed.

The temperature is a temperature at which the transfer film reaches the maximum film surface temperature in the pasting step.

After the above-described attaching step, the support 12 is peeled off from the transfer film 10 attached to the substrate P. As a result, as shown in fig. 5, a wiring board 100 is obtained by transferring a laminate in which a solvent permeation layer 18 having a wiring pattern formed thereon, a receiving layer 16, and a protective layer 14 are laminated in this order on a substrate P (peeling step, see fig. 5).

Although not performed in the above-described manufacturing method, it is preferable to expose the wiring pattern after the wiring pattern forming step. This causes the wiring pattern to be optically sintered, which lowers the electrical resistance of the wiring pattern.

The exposure is not particularly limited as long as it is performed after the wiring pattern formation step, but is preferably performed before the peeling step.

The exposure is performed by irradiating ultraviolet rays using a trade name "PulseForge 3300" manufactured by Novacentrix corporation, for example.

The exposure conditions may be set to a degree that deformation of the transfer film 10 does not occur, according to known conditions. For example, the irradiation energy is preferably 1 to 20J/cm²The pulse irradiation time is preferably 10 to 10000. mu.s, and the number of irradiation times is preferably 5 to 30.

In the present manufacturing method, as shown in fig. 4 and 5, the wiring substrate 100 may be manufactured using a transfer film in a cut sheet form, but a long transfer film may be used, and the transfer film may be attached to the substrate while the transfer film and the substrate are moved at the same speed in the longitudinal direction of the transfer film to manufacture the wiring substrate.

Fig. 4 and 5 show an example of manufacturing a wiring board 100 in which 1 set of laminates (the solvent permeation layer 18, the receiving layer 16, and the protective layer 14 on which the wiring pattern is formed) is laminated on the substrate P, but in the present manufacturing method, a wiring board (multilayer wiring board) in which 2 or more sets of laminates are laminated on the substrate P may be manufactured.

That is, another embodiment of the present manufacturing method includes a method of obtaining a wiring board by repeating the following steps to laminate a plurality of wiring patterns on the substrate: after a new transfer film on which the wiring pattern obtained in the wiring pattern forming step is formed is attached to the wiring substrate obtained in the peeling step, the support in the new transfer film is peeled. Thus, a wiring board (multilayer wiring board) in which a plurality of wiring patterns are laminated on a substrate is obtained.

Hereinafter, an example of manufacturing a wiring board in which 2 or more sets of the laminate are laminated on the substrate P will be specifically described with reference to the drawings.

First, a new transfer film X1 on which the wiring pattern obtained in the wiring pattern formation step is formed is prepared (preparation step).

As shown in fig. 6, transfer film X1 is formed by laminating protective layer 14A, receiving layer 16A, and solvent-permeated layer 18A having a wiring pattern formed thereon in this order on one surface of support 12A.

Next, the solvent permeation layer 18A of the transfer film X1 is brought into contact with the protective layer 14 of the wiring substrate 100 obtained by the peeling step described in fig. 5, and the transfer film X1 and the wiring substrate 100 are bonded (the bonding step of the transfer film X1, refer to fig. 6).

Next, the support 12A is peeled from the transfer film X1 (peeling step using transfer film X1, see fig. 7). As a result, as shown in fig. 7, a wiring board 200 in which 2 laminates having wiring patterns were laminated on the substrate P was obtained.

Here, when 2 or more transfer films are prepared in the preparation step, the wiring substrate can be further multilayered. This embodiment will be described with reference to fig. 8 and 9.

As shown in fig. 8, transfer film X2 is formed by laminating protective layer 14B, receiving layer 16B, and solvent-permeable layer 18B having a wiring pattern formed thereon in this order on one surface of support 12B.

First, after the peeling step using the transfer film X1, the transfer film X2 and the wiring substrate 200 are bonded by bringing the solvent permeation layer 18B of the transfer film X2 into contact with the protective layer 14A of the wiring substrate 200 (the bonding step using the transfer film X2, see fig. 8).

Next, the support 12B is peeled from the transfer film X2 (peeling step using transfer film X2, see fig. 9). As a result, as shown in fig. 9, a wiring board 300 in which 3 laminates having wiring patterns were laminated on the substrate P was obtained.

By repeating the steps shown in fig. 8 and 9 in this manner, a wiring board in which a laminate having wiring patterns is laminated in an arbitrary number can be obtained.

The wiring board obtained by the present manufacturing method is preferably used for forming a circuit for maintaining the safety of a card-like object such as a riding card, a credit card, an electronic money card, an ID (identification) card, a card key, or various score cards for a train, a bus, or the like, a complicated RF (radio frequency) chip for enhancing the confidentiality of various information, and an antenna circuit for energy collection.

In particular, the wiring board is preferably a thin film.