KR101771951B1 - Method of fabricating a transparent flexible circuit board - Google Patents

Abstract

A method of manufacturing a transparent double-sided circuit board, comprising the steps of: (a) forming a hole by drilling a substrate having a conductive film on both surfaces thereof as a starting material so as to penetrate the substrate; (b) coating the surface of the conductive film of the substrate and the inner wall of the hole with a conductive film; (c) a line having a width of W and a line having a distance of L (W? L) are formed by coating an etched mask on which a circuit pattern in which a network structure of a predetermined mesh shape is repeated is coated on the substrate surface and the exposed conductive film is etched, Forming a circuit embodying a wire in a net in which a mesh shape is repeated; (d) stripping the etch mask and forming a coverlay (C / L) on the circuit; And (e) a step of finishing the exposed copper (Cu) surface to form a film, wherein a ratio of the width W of the line to the length of the lapan interval L is adjusted to adjust the light transmittance The method comprising the steps of: preparing a transparent double-sided circuit board (PCB)

Description

[0001] METHOD OF FABRICATING A TRANSPARENT FLEXIBLE CIRCUIT BOARD [0002]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent flexible circuit board (FPCB), and more particularly, to a method of manufacturing a transparent flexible circuit board in which a circuit is formed on both sides of a substrate.

As electronic products are miniaturized and portability is increased, a function of bending or folding is required. Accordingly, a circuit board constituting an electronic product is required to be formed in a form having a function of bending or bending.

A new type of display device such as a head-up display (HUD) or a head-mounted display (HMD) has been introduced to the market and transparent electronic products such as electronic devices built in automobile glass have been developed, It is required to have a transparent and flexible characteristic.

In particular, oxide transparent electrodes such as indium tin oxide (ITO) and indium zinc oxide (IZO) are used as sign boards for LED modules. 1 is a photograph showing an ITO electrode applied to an LED module according to a related art. However, since the ITO electrode according to the prior art lacks the high resistance value and the bending force of the ITO electrode, there is a technical limitation in applying the ITO electrode to the flexible circuit board.

Meanwhile, as the number of pins of the LED chip increases for various color hues and signal control, there is an increasing need to develop a manufacturing technique for implementing a substrate circuit for driving an LED chip on both sides instead of a cross section. In addition, there is a disadvantage that the heat dissipation characteristics are insufficient when the LED driving module is manufactured in a cross section.

1. Korean Patent Publication No. 10-2005-0024072. 2. Korean Patent Publication No. 10-2008-0000017.

A first object of the present invention is to provide a method for manufacturing a double-sided transparent flexible circuit board.

A second object of the present invention is to provide, in addition to the first object, a method of manufacturing a double-sided transparent flexible circuit board having a conductor having good flexibility and conductivity.

A third object of the present invention is to provide a method for manufacturing a double-sided transparent flexible circuit board with improved heat dissipation in addition to the first and second objects.

In order to accomplish the above object, the present invention provides a method of manufacturing a transparent double-sided circuit board, comprising the steps of: (a) forming a transparent base film on a surface of a substrate coated with a conductive film as a starting material, Thereby forming a hole; (b) coating the surface of the conductive film of the substrate and the inner wall of the hole with a conductive film; (c) a line having a width of W and a line having a distance of L (W? L) are formed by coating an etched mask on which a circuit pattern in which a network structure of a predetermined mesh shape is repeated is coated on the substrate surface and the exposed conductive film is etched, Forming a circuit embodying a wire in a net in which a mesh shape is repeated; (d) stripping the etch mask and forming a coverlay (C / L) on the circuit; And (e) a step of finishing the exposed copper (Cu) surface to form a film, wherein a ratio of the width W of the line to the length of the lapan interval L is adjusted to adjust the light transmittance The method comprising the steps of: preparing a transparent double-sided circuit board (PCB)

According to the present invention, since the conductor constituting the double-sided circuit portion forms a net structure by the fine lines and the mesh, transparency can be imparted to the conductor even when opaque conductive metal or conductive film (for example, copper foil) is used. Accordingly, the resistance of the circuit can be reduced by forming a conductive line using a metal having excellent conductivity and flexibility, and a two-layer circuit having a constant electric conductivity without breaking the circuit despite repeated bending operations is provided.

1 is a photograph showing an ITO electrode applied to an LED module according to a prior art.
FIGS. 2A to 2C are views showing various embodiments for manufacturing a lead wire applied to a double-sided transparent flexible circuit board according to the present invention. FIG.
3A to 3J show a method of manufacturing a double-sided transparent flexible circuit board according to the present invention.
Figs. 4A and 4B are views showing the case where PTH is arranged on the mounting pad portion and the case where LVH is arranged, respectively, in accordance with the preferred embodiment of the present invention. Fig.
5A and 5B are views showing a chip mounted on a both-side transparent substrate manufactured according to the present invention.

Hereinafter, a method of manufacturing a double-sided transparent flexible circuit board according to the present invention will be described in detail with reference to FIGS. 2 to 5.

FIGS. 2A to 2C are views illustrating various embodiments of manufacturing a wire to be applied to the double-sided transparent flexible circuit board according to the present invention. 2A to 2C, in order to secure transparency and flexibility, a lead wire to be applied to the circuit board of the present invention may be formed by a wire having a predetermined width and thickness, And a wire net is formed of a mesh net composed of the wire net. That is, the present invention realizes transparency by constructing a wire in the form of a net having a polygon such as a quadrangle, a hexagon, or an octagon as a basic unit.

As a result, the conductive line according to the present invention has a net structure by a fine line and a mesh, and even if an opaque metal is used, a sufficient space is provided between the fine line and the fine line Thereby imparting transparency to the lead wire. Accordingly, the conductor or electrode portion according to the present invention has excellent conductivity, transparency and flexibility, and not only breaks the circuit even in a bending operation, but also has good light transmittance.

The net-shaped conductor according to the present invention can be made of copper (Cu), but it is not necessarily limited to copper. Any one or a combination of iron (Fe), gold (Au), silver (Ag), nickel (Ni), platinum (Pt), chromium (Cr) and molybdenum (Mo) have.

It is preferable that the line width W of the net-shaped conductor according to the present invention is 70 mu m or less and the interval L between the lines forming the net shape is 200 mu m or more. Further, the thickness T of the mesh line according to the present invention can be used in a range of 72 mu m or less. As a preferred embodiment of the present invention, the effective width of a circuit composed of repeated lines and meshes is preferably in the range of 0.1 to 3 mm in total of the width W of the line and the L of the mesh.

3A to 3J are views showing a method of manufacturing a double-sided transparent flexible circuit board according to the present invention. Hereinafter, the concept of the present invention will be described by exemplifying the figure (Cu) in the detailed description, but it is not necessarily limited to copper (Cu).

Referring to FIG. 3A, as a preferred embodiment of the present invention, a flexible copper clad laminate (FCCL) material can be fabricated as a starting material.

The transparent flexible copper-clad laminate film (FCCL) according to the present invention is a substrate in which a copper foil 10a is coated on both surfaces of a thin insulating insulating transparent base film 10b of about ten micrometers. In particular, the insulating base film 10b has transparency do.

Since the FCCL 10 according to the present invention has good light transmittance (? 80%), it is characterized by using a transparent base film. As a preferred embodiment of the transparent base film 10b according to the present invention, the transparent base film 10b may be made of a material selected from the group consisting of polyethylene terephthalate (PET), polyethyle naphthalate (PEN), poly methyl sulfone (PES), ply amide imide (PP) methyl methacrylate), TAC (triacetyl cellulose), PC (poly carbonate), PAC (poly acrylic), COC (cyclic olefin copolymer), polystyrene, transparent polyimide, nylon, polytetrafluoroethylene polyether ether ketone) and the like, and the thickness is preferably 200 μm or less.

The base film 10b and the copper foil 10a are adhered to each other with an adhesive agent (not shown). Preferably, the adhesive agent has a light transmittance of 80% or more. An epoxy resin, an acrylic resin, a urethane resin, PAI-based resin, polystyrene-based resin, cyanoacrylate-based resin, or the like, or one or more resins may be impregnated and used.

Referring to FIG. 3B, holes 12 can be formed for electrically connecting circuits on both surfaces by using a laser drill or a mechanical drill method. As a preferred embodiment of the present invention, a Plated Through Hole (PTH) or a Laser Via Hole (LVH) can be fabricated (see PTH in FIG. 4A and LVH in FIG. 4B).

Referring to FIG. 3C, when copper plating is performed, copper (Cu) is coated on the both surfaces 10a of the FCCL 10 and the inner walls of the holes 12. Referring to FIG. 3D, a dry film (D / F) 20 is closely contacted to both surfaces of the substrate.

Subsequently, when the exposure and development work is carried out in accordance with a predetermined circuit pattern (see Figs. 3E and 3F), the circuit pattern is transferred to the dry film 20. The circuit pattern is formed by etching the copper foil 10a whose surface is exposed using the dry film 20 transferred with the pattern as an etching mask. At this time, the pattern of the wire of the net structure type according to the present invention is formed.

That is, as described above, in manufacturing a circuit according to the present invention, in order to secure transparency, a plurality of fine lines arranged in a net shape and a plurality of fine lines And the copper foil circuit is implemented by a plurality of net structures formed by the copper foil. That is, the present invention realizes transparency by constituting a copper foil circuit in the form of a polygonal net.

As a result, the conductor formed by the copper foil has a net-like structure by a fine line and a mesh. Even if an opaque metal is used, a sufficient empty space is placed between the fine line and the fine line. Thereby imparting transparency thereto. Accordingly, the transparent flexible circuit part according to the present invention not only breaks the circuit even in a flexing operation, but also has good light transmittance by forming a conductive line excellent in conductivity and flexibility.

Referring to FIG. 3H, after the copper foil circuit embodying the wire of the present invention is formed, the dry film 20 used as the etching mask is peeled off.

Referring to FIG. 3I, a coverlay (C / L) 30 is closely attached to both sides of a substrate. The coverlay 30 according to the present invention should be made of a material having transparency and may be made of an epoxy resin, an acrylic resin, a urethane resin, a PET resin, a PAI resin, a polystyrene resin, And an adhesive using a cyanoacrylate resin as a raw material or one or more resins may be impregnated and used.

As a preferable example of a transparent adhesive capable of replacing transparent coverlay, a transparent adhesive having a light transmittance of 80% or more is preferably used as the transparent adhesive in the case of an epoxy resin, an acrylic resin, a urethane resin, a PET resin, a PAI resin, a polystyrene resin, An epoxy resin containing an acrylonitrile-butadiene rubber (NBR), an ethylene / acrylic ester copolymer resin, and the like as a raw material, such as an acrylate resin, a phenol acrylate resin, a phenoxy acrylate resin, a fluorine resin, an ethylene- Or one or more resins may be impregnated and used. Referring to FIG. 3J, a finishing process such as gold plating or OSP coating is performed.

4A and 4B are views showing the case where PTH is arranged on the mounting pad portion and the case where LVH is arranged according to the preferred embodiment of the present invention. 4A and 4B, transparency of the substrate can be secured by manufacturing PTH and LVH at the chip mounting site or at the bottom of the chip mounting site.

5A and 5B are views showing a chip mounted on a double-sided transparent substrate manufactured according to the present invention. 5A and 5B, the copper foil 10a forms a wire or electrode having a net structure, and the LED chip 50 is mounted.

The foregoing has somewhat improved the features and technical advantages of the present invention in order to better understand the claims of the invention described below. Additional features and advantages that constitute the claims of the present invention will be described in detail below. It should be appreciated by those skilled in the art that the disclosed concepts and specific embodiments of the invention can be used immediately as a basis for designing or modifying other structures to accomplish the invention and similar purposes.

The inventive concepts and embodiments disclosed herein may be used by those skilled in the art as a basis for modifying or designing other structures to accomplish the same purpose of the present invention. It will be apparent to those skilled in the art that various modifications, substitutions and alterations can be made hereto without departing from the spirit or scope of the invention as defined in the appended claims.

The circuit board manufacturing technique of the present invention is characterized in that a flexible and flexible circuit is formed on both sides of the substrate. The present invention can form a two-layer circuit so that a variety of signals can be transmitted by making copper (Cu) on both sides of the substrate patterned in a mesh pattern so that both surfaces are transparent and a copper foil circuit can be formed on both sides. In addition, the heat radiation effect of the substrate can be improved by implementing the double-sided circuit, and the transparency of the substrate can be ensured by arranging the hole position below the chip to be mounted. As a result, it becomes possible to manufacture a head-up display, a head-mounted display, or a new concept transparent electronic product.

Claims (8)

A method of manufacturing a transparent flexible circuit board on which circuits are formed on both sides,
(a) A transparent and ductile base film A hole is formed by drilling the FCCL substrate so that the FCCL substrate having both surfaces thereof covered with a copper foil is passed through the FCCL substrate, Wherein the step of laying is performed so as to be positioned at the lower end of the mounting site;
(b) performing copper plating to cover the surface of the double-sided copper foil of the FCCL board and the inner wall of the hole with copper;
(c) arranging and etching an etched mask on which a circuit pattern in which a predetermined mesh-like net structure is repeated is transferred to both surfaces of the FCCL substrate, thereby obtaining a mask having a width W (W? 70 占 퐉) L, L ≥ 200 mu m);
(d) removing the etching mask and forming a coverlay (C / L) on the copper foil circuit; And
(e) Finishing the exposed copper (Cu) surface to form a coating
Wherein a sum of the width W of the line and the lane distance L is in the range of 0.1 to 3 mm and the length ratio of the width W of the line to the lane distance L is set to Wherein the circuit is implemented on both sides of the substrate by adjusting the light transmittance and the electrical conductivity. delete delete delete delete delete delete delete

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