JP2010028030A - Manufacturing method of printed wiring board - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a manufacturing method of a printed wiring board wherein a conductive portion is not broken easily and the conductive property of the conductive portion is excellent in forming the conductive portion having a predetermined shape on the board by using a polymer type conductive ink. <P>SOLUTION: The manufacturing method of a printed wiring board provides for a printed wiring board having a board and a conductive portion provided on its one side surface. The manufacturing method has a process A for forming a coated film as the conductive portion by coating the one surface with a polymer type conductive ink and a process B for impressing an electric field between the other surface of the board and the outermost surface of the coated film, and moving conductive microparticles included in the coated film to the outermost surface side of the coated film. <P>COPYRIGHT: (C)2010,JPO&INPIT

Description

  The present invention relates to a method for manufacturing a printed wiring board, and more particularly to a method for manufacturing a printed wiring board excellent in conductivity of a conductive portion formed using a polymer-type conductive ink.

Conventionally, by using a conductive paste (polymer type conductive ink) in which conductive fine particles are contained in a resin composition (binder), a circuit having a predetermined shape (conductive) is formed on a substrate by a printing method such as an inkjet method or a screen printing method. The printed wiring board is manufactured.
As a printed wiring board provided with a conductive portion made of such a conductive paste, for example, a non-contact type IC card in which antenna wiring is formed on the board with a conductive paste is disclosed (for example, Patent Document 1, 2). In this non-contact type IC card, after the conductive paste is printed on the surface of the inlet sheet, the inlet sheet is heated to cure the thermosetting binder resin component in the conductive paste, thereby forming the antenna wiring.
JP 2003-242472 A JP 2003-223626 A

  However, although the conductive part made of the conductive paste has high adhesion to the substrate, there is a problem that the resistance value is relatively high because of the large amount of the resin composition with respect to the conductive fine particles. Further, when the conductive portion is formed on the plastic substrate using the conductive paste, there is a problem that when the substrate is bent, the conductive portion is destroyed and the conductivity is impaired.

  The present invention has been made in view of the above circumstances, and when a conductive part having a predetermined shape is formed on a substrate using a polymer-type conductive ink, the conductive part is not easily destroyed, and An object of the present invention is to provide a method for manufacturing a printed wiring board having excellent conductivity of a conductive portion.

  A method for manufacturing a printed wiring board according to the present invention is a method for manufacturing a printed wiring board comprising a substrate and a conductive portion provided on one surface of the substrate, wherein the polymer-type conductive material is provided on one surface of the substrate. Applying ink to form a coating film forming a conductive portion, and applying an electric field between the other surface of the substrate and the outermost surface of the coating film, the conductive fine particles contained in the coating film And a step B of moving to the outermost surface side of the coating film.

  According to the method for manufacturing a printed wiring board of the present invention, there is provided a method for manufacturing a printed wiring board comprising a substrate and a conductive portion provided on one surface of the substrate, wherein the polymer is formed on one surface of the substrate. A conductive film contained in the coating film by applying an electric field between the other surface of the substrate and the outermost surface of the coating film. Step B of moving the fine particles to the outermost surface side of the coating film, the obtained printed wiring board has a higher content of conductive fine particles per unit volume on the outermost surface side of the conductive portion, As a result, a large number of conductive fine particles come into close contact with each other, and the large number of conductive fine particles form one conductor along the longitudinal direction of the conductive portion. Therefore, the conductive portion is excellent in conductivity, and the conductive portion is not easily broken even when the printed wiring board is bent.

The best mode of the method for producing a printed wiring board of the present invention will be described.
This embodiment is specifically described for better understanding of the gist of the invention, and does not limit the present invention unless otherwise specified.

  A method for manufacturing a printed wiring board according to the present invention is a method for manufacturing a printed wiring board comprising a substrate and a conductive portion provided on one surface of the substrate, wherein the polymer-type conductive material is provided on one surface of the substrate. Applying ink to form a coating film forming a conductive portion, and applying an electric field between the other surface of the substrate and the outermost surface of the coating film, the conductive fine particles contained in the coating film And a step B of moving to the outermost surface side of the coating film.

Hereinafter, with reference to FIGS. 1-4, one Embodiment of the manufacturing method of the printed wiring board of this invention is described.
First, as shown in FIG. 1, a polymer-type conductive ink is applied to one surface 1a of the substrate 1 by a printing method to form an undried coating film 2 forming a conductive portion of a predetermined shape (step A). ).
In this step A, the shape of the undried coating film 2 is the shape of a conductive portion made of a predetermined circuit, antenna, or the like.
As a printing method, an ink jet method, a screen printing method, or the like is used.

  As the substrate 1, at least in the surface layer portion, a woven fabric made of inorganic fibers such as glass fibers or alumina fibers, a nonwoven fabric, a mat, paper, or a combination thereof, or a woven fabric made of organic fibers such as polyester fibers or polyamide fibers. Cloth, non-woven fabric, mat, paper, etc., or a combination thereof, or a covering member formed by impregnating them with a resin varnish, polyamide resin substrate, polyester resin substrate, polyolefin resin substrate, polyimide Resin base material, ethylene-vinyl alcohol copolymer base material, polyvinyl alcohol resin base material, polyvinyl chloride resin base material, polyvinylidene chloride resin base material, polystyrene resin base material, polycarbonate resin base material, Acrylonitrile butadiene styrene copolymer resin base material, polyethersulfone type Plastic base materials such as fat base materials, (glass) epoxy resin base materials, or these, mat processing, corona discharge processing, plasma processing, ultraviolet irradiation processing, electron beam irradiation processing, flame plasma processing, ozone processing, or various eases It selects from well-known things, such as what gave surface treatments, such as adhesion processing, and is used.

Examples of polymer-type conductive inks are those in which conductive fine particles such as silver powder, gold powder, platinum powder, aluminum powder, palladium powder, rhodium powder, carbon powder (carbon black, carbon nanotube, etc.) are blended in the resin composition Is mentioned.
If a thermosetting resin is used as the resin composition, the polymer type conductive ink becomes a thermosetting type capable of forming a coating film forming a conductive part at 200 ° C. or less, for example, about 100 to 150 ° C. A path through which electricity of the coating film forming the conductive portion flows is formed by contact of the conductive fine particles forming the coating film with each other, and the resistance value of the coating film is on the order of 10 ⁻⁵ Ω · cm.
Further, as the polymer type conductive ink in the present invention, known ones such as a photocuring type, a penetrating drying type, and a solvent volatilization type are used in addition to the thermosetting type.

  The photocurable polymer type conductive ink contains a photocurable resin in the resin composition and has a short curing time, so that the production efficiency can be improved. Examples of the photo-curing polymer type conductive ink include, for example, a thermoplastic resin alone, or a blend resin composition of a thermoplastic resin and a crosslinkable resin (particularly, a crosslinkable resin composed of polyester and isocyanate) and 60 fine conductive particles. More than 10% by mass and 10% by mass or more of a polyester resin, that is, a solvent volatile type or a crosslinked / thermoplastic combined type (however, the thermoplastic type is 50% by mass or more), thermoplastic A resin resin or a blend resin composition of a thermoplastic resin and a crosslinkable resin (especially a crosslinkable resin composed of polyester and isocyanate) is blended with 10% by mass or more of a polyester resin, that is, a crosslinkable type or a crosslinked / crosslinked resin. A thermoplastic combination type is preferably used.

  Next, as shown in FIG. 2, the positive electrode 21 is disposed in contact with the other surface 1 b of the substrate 1, and the surface (outermost surface) 2 a opposite to the surface in contact with the substrate 1 of the coating film 2. After the negative electrode 22 is arranged close to the substrate, a predetermined voltage is applied to the positive electrode 21 and the negative electrode 22, so that the substrate 1 is placed between the other surface 1 b of the substrate 1 and the outermost surface 2 a of the coating film 2. The electric field is applied in a direction perpendicular to the one surface 1a of 1 and the outermost surface 2a of the coating film 2 and from the one surface 1a of the substrate 1 toward the outermost surface 2a of the coating film 2 (arrow direction in the figure). Multiply. Thereby, as shown in FIG. 3, the conductive fine particles 4 contained in the resin composition 3 of the polymer type conductive ink forming the coating film 2 are moved to the outermost surface 2a side of the coating film 2 (step B).

The magnitude of the voltage applied to the positive electrode 21 and the negative electrode 22 is appropriately adjusted according to the content of the conductive fine particles 4 in the polymer type conductive ink, but the conductive fine particles 4 are on the outermost surface 2 a side of the coating film 2. It is preferable that the movement is sufficient.
The time for applying the voltage to the positive electrode 21 and the negative electrode 22 is not particularly limited, but it is preferable that the conductive fine particles 4 are sufficiently moved to the outermost surface 2a side of the coating film 2.

In this process B, the electroconductive fine particles 4 are moved to the outermost surface 2a side of the coating film 2 using electromigration or ion migration.
Electromigration is a phenomenon in which a metal component moves across or across a non-metallic medium due to the influence of an electric field. In this phenomenon, the metal component is in a metal state before and after movement, and exhibits conductivity. In that sense, it can be said that the phenomenon (the occurrence of a corrosive product) in which a stain appears to exude due to metal corrosion (oxidation, halogenation, etc.) is not electromigration. However, corrosive products are often confused because their occurrence is similar to electromigration (eg, dendritic). The major difference between the two migrations is the presence or absence of an electric field. Corrosive products occur without an electric field, but electromigration does not occur without an electric field.

Ion migration will be described.
A case where the polymer type conductive ink includes, for example, silver (Ag) particles as the conductive fine particles will be exemplified.
The potential difference between the positive electrode 21 and the negative electrode 22 and the presence of water adsorbed on the surface of the coating film 2 from the surrounding atmosphere cause ionization of silver particles as shown in the following formula (1). Water ionization occurs as shown in (2).
Ag → Ag ⁺ (1)
H ₂ O → H ⁺ + OH ⁻ (2)

Ag ⁺ and OH ⁻ are precipitated as AgOH on the positive electrode 21 side as shown in the following formula (3).
Ag ⁺ + OH ⁻ → AgOH (3)
Furthermore, AgOH decomposes as shown in the following formula (4) is dispersed in the positive electrode 21 side Ag ₂ O, and the colloidal.
2AgOH⇔Ag ₂ O + H ₂ O (4)

Thereafter, a hydration reaction occurs as shown in the following formula (5).
Ag ₂ O + H ₂ O⇔2AgOH⇔2Ag ⁺ + 2OH ⁻ (5)
When the reaction shown in the above formula (5) proceeds, Ag ⁺ moves to the negative electrode 22 side, and as a result, Ag dendritic precipitation proceeds on the outermost surface 2a side of the coating film 2.

  Next, the undried coating film 2 is heated and dried to form the conductive portion 5 (step C).

  The printed circuit board 10 provided with the board | substrate 1 and the electroconductive part 5 provided in the one surface 1a of the board | substrate 1 by the above process AC is obtained.

  According to the method for manufacturing a printed wiring board of this embodiment, polymer-type conductive ink is applied to one surface 1a of the substrate 1 to form an undried coating film 2 that forms a conductive portion, and the other side of the substrate 1 is formed. An electric field is applied between the surface 1b of the coating film 2 and the outermost surface 2a of the coating film 2 to move the conductive fine particles 4 contained in the coating film 2 to the outermost surface 2a side of the coating film 2, and then the coating film 2 is heated. Since the conductive portion 5 is formed by drying, the content of the conductive fine particles 4 per unit volume is increased on the surface (outermost surface) 5a side opposite to the surface in contact with the substrate 1 of the conductive portion 5, As a result, the large number of conductive fine particles 4 come into close contact with each other, and the large number of conductive fine particles 4 form one conductor along the longitudinal direction of the conductive portion 5. Therefore, the conductive portion 5 is excellent in conductivity, and the conductive portion 5 is not easily broken even when the printed wiring board 10 is bent.

  In this embodiment, an electric field is applied between the other surface 1b of the substrate 1 and the outermost surface 2a of the coating film 2 in the undried state, so that the outermost surface 2a side of the coating film 2 is present. However, the present invention is not limited to this. In the present invention, an undried coating film applied on a substrate is heated and dried to form a conductive portion, and then an electric field is applied between the other surface of the substrate and the outermost surface of the conductive portion. Also good.

It is a schematic sectional drawing which shows one Embodiment of the manufacturing method of the printed wiring board of this invention. It is a schematic sectional drawing which shows one Embodiment of the manufacturing method of the printed wiring board of this invention. It is a schematic sectional drawing which shows one Embodiment of the manufacturing method of the printed wiring board of this invention, and is the figure which expanded the area | region enclosed with the broken line A of FIG. It is a schematic sectional drawing which shows one Embodiment of the manufacturing method of the printed wiring board of this invention.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 ... Board | substrate, 2 ... Coating film, 3 ... Resin composition, 4 ... Conductive fine particle, 5 ... Conductive part, 10 ... Printed wiring board, 21 ... Positive electrode, 22 ... negative electrode.

Claims (1)

A printed wiring board manufacturing method comprising a substrate and a conductive portion provided on one surface of the substrate,
Step A of applying a polymer type conductive ink on one surface of the substrate to form a coating film forming a conductive portion;
A step B in which an electric field is applied between the other surface of the substrate and the outermost surface of the coating film, and the conductive fine particles contained in the coating film are moved to the outermost surface side of the coating film. A printed wiring board manufacturing method characterized by the above.

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