KR20150134777A - Transparent flexible-rigid circuit board and manufacturing method thereof - Google Patents

Abstract

The flexible circuit portion of the circuit board according to the present invention comprises: a transparent base film; On the transparent base film, a line having a thickness T and a width W and a mesh having a lanthanum spacing L (W? L) are repeatedly formed. By adjusting the length ratio of L and W, light transmittance and electrical conductivity A first circuit of a regulating net structure; And the transparent insulating layer formed on the upper surface of the transparent base film so as to cover the circuit, the flexible circuit portion has transparency.
In the hard circuit portion according to the present invention, an insulating layer and a conductive layer are stacked on a predetermined area of the upper surface of the transparent insulating layer of the flexible circuit part, and a series of general printed circuit board processes such as photo, etching, plating, And a second circuit formed by transferring a predetermined pattern to the conductive layer. Wherein the flexible circuit portion has transparency.

Description

FIELD OF THE INVENTION [0001] The present invention relates to a transparent soft circuit board and a manufacturing method thereof,

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transparent flexible circuit board (R / F), in particular, a flexible circuit board and a rigid circuit board are integrated into one body, And a manufacturing technology thereof.

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.

Furthermore, in recent years, new types of display devices such as a head-up display (HUD) or a head-mounted display (HMD) have been introduced to the market and transparent electronic products such as electronic devices built in automobile glasses have been developed, It is required that the circuit board to be driven be transparent and flexible.

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

1. Choi, Won-Kook, "Flexible Electronic Substrate Using Vacuum Web Coating: Flexible Circuit Substrate, RFID, Transparent Touch Panel," Packaging Society Volume 183, July 2008, pp.11-123, 1228-2863.

A first object of the present invention is to provide a circuit board and a manufacturing method in which a transparent flexible circuit part and a hard circuit part are integrated into one.

A second object of the present invention is to provide a circuit structure of a transparent flexible circuit part having a good electrical conductivity and a soft characteristic that it is not damaged by repeated bending operations, And the light transmittance in the flexible circuit portion is guaranteed to be 80% or more with respect to the visible light region.

In order to achieve the above object, a flexible circuit part of a circuit board according to the present invention comprises: a transparent base film; On the transparent base film, a line having a thickness T and a width W and a mesh having a lanthanum spacing L (W? L) are repeatedly formed. By adjusting the length ratio of L and W, light transmittance and electrical conductivity A first circuit of a regulating net structure; And the transparent insulating layer formed on the upper surface of the transparent base film so as to cover the circuit, the flexible circuit portion has transparency.

In the hard circuit portion according to the present invention, an insulating layer and a conductive layer are stacked on a predetermined area of the upper surface of the transparent insulating layer of the flexible circuit part, and a series of general printed circuit board processes such as photo, etching, plating, And a second circuit formed by transferring a predetermined pattern to the conductive layer.

The present invention provides a method of fabricating a circuit board in which a flexible circuit portion and a rigid circuit portion are integrated into one, comprising the steps of: (a) preparing a core substrate on which a first conductive layer is coated on a transparent base film; (b) a circuit pattern is transferred to the first conductive layer to fabricate a first circuit, wherein the circuit pattern of the first circuit includes a line having a thickness T and a width W and a line having a width L (W? L) Fabricating a first circuit of a net structure that regulates the light transmittance and the electrical conductivity by regulating the length ratio of L and W to the mesh; (c) forming a transparent insulating layer on the entire surface of the first circuit formed on the upper surface of the transparent base film; And (d) a second insulating layer and a second conductive layer are stacked on a predetermined region of the upper surface of the transparent insulating layer, and a series of general printed circuit board processes such as photo, etching, plating, Forming a second circuit by transferring a predetermined pattern onto the layer.

In addition, the step of forming a transparent insulating layer according to the present invention includes the steps of: (c1) printing and curing a transparent ink; (c2) applying and curing a transparent adhesive; (c3) contacting the transparent coverlay and subjecting the laminate to heat-pressure lamination.

Since the conductor constituting the flexible circuit part of the present invention forms a net structure by the fine lines and the mesh, transparency can be imparted to the conductor even when an opaque conductive metal (for example, copper foil) is used, By using this excellent metal to form a conductor, it is possible to reduce the surface resistance of the circuit and to provide a circuit having a constant electric conductivity without breaking the circuit despite repeated bending operations.

The present invention makes it possible to manufacture a head-up display, a head-mounted display or a new concept of a transparent electronic product by providing a method of manufacturing a circuit board in which a flexible circuit portion and a general hard-circuit portion are integrated into one, .

BRIEF DESCRIPTION OF THE DRAWINGS FIG. 1A and FIG. 1B are views schematically showing an embodiment of a transparent soft circuit board according to the present invention. FIG.
2A to 2I are views showing an embodiment of a method of manufacturing a transparent soft circuit board according to the present invention.
Figs. 3A to 3C are views showing various embodiments of the copper-net circuit of the net structure according to the present invention

Hereinafter, a transparent soft circuit board and a manufacturing method according to the present invention will be described in detail with reference to the accompanying drawings.

The transparent soft circuit board according to the present invention is characterized in that a transparent flexible circuit part 100 and a rigid circuit part 200 are integrally formed. Figs. 1A and 1B are views schematically showing an embodiment of a transparent soft circuit board according to the present invention.

1A shows a first embodiment of the present invention. A rigid circuit part 200 is fabricated at both ends of a transparent flexible circuit part 100 in the center. FIG. 1B shows a second embodiment of the present invention, in which the hard circuit part 200 is fabricated at one end of the transparent flexible circuit part 100. FIG.

The present invention is characterized in that a circuit board is manufactured by first fabricating a transparent flexible circuit part, then laminating a prepreg (PREPREG) and a copper foil in an area where a hard circuit part is required, and then proceeding a general printed circuit board process such as etching, plating, .

FIGS. 2A to 2I are views showing a preferred embodiment of a method of manufacturing a transparent soft circuit board according to the present invention, wherein FIGS. 2A to 2F are views showing a step of manufacturing a transparent flexible circuit part, 2I are diagrams showing process steps for fabricating the hard circuit.

Referring to FIG. 2A, as a preferred embodiment of the present invention, a flexible circuit portion can be fabricated first using a flexible copper clad laminate (FCCL) material as a starting material. The transparent flexible copper-clad laminate film (FCCL) according to the present invention is a substrate to which a copper foil 10a is attached on a thin insulating transparent base film 10b having a thickness of about ten micrometers. Particularly, the insulating base film 10b has transparency.

In the following detailed description of the present invention and claims, the concept of the present invention will be described focusing on copper (Cu) as an embodiment of the conductive metal. However, as the metal forming the conductive circuit of the circuit board according to the present invention, Cu). In addition to copper (Cu), any one of or a combination of iron (Fe), gold (Au), silver (Ag), nickel (Ni), platinum (Pt), and molybdenum (Mo)

In the case of a flexible circuit board according to the related art, since the flexible circuit part has good light transmittance (? 80%) while the polyimide (PI) with orange color is used as the base film, Is used. In addition, in the present invention, it is necessary to laminate the prepreg and the copper foil on the flexible circuit part after the flexible circuit part is manufactured and to perform post-heat lamination, so that the transparent base film according to the present invention is not deformed during the lamination process It is necessary to have high heat resistance.

(PET), polypropylene (PP), poly methyl methacrylate (PMMA), polyethyl methacrylate (PMMA), polyethyleneterephthalate (PEN) Polyacetal, nylon, polytetrafluoroethylene (PTFE), polyether ether (PEEK), polyetheretherketone (PAC), polyacetal ketone, and the like, and the thickness is preferably 200 占 퐉 or less.

2B, a dry film (D / F) 20 is brought into direct contact with the copper foil 10a, and then a series of image processes such as photo, development and etching are performed to transfer a circuit pattern onto the dry film 20 do.

However, in manufacturing the copper-clad circuit of the transparent flexible circuit part 100 of the present invention, in order to secure transparency, a plurality of fine lines arranged in a net (net) instead of a conventional copper- And a copper foil circuit is implemented by a plurality of meshes formed by the fine lines. That is, the present invention realizes transparency by configuring a copper foil circuit in the form of a polygonal mesh.

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.

As a preferred embodiment of the present invention, transparency can be realized by increasing the light transmittance by making the width W of the fine lines thin to 1 to 100 mu m and widening the interval L between the lines to 100 to 1000 mu m. The thickness T of the copper foil for realizing the mesh-type copper-clad circuit according to the present invention may be in the range of 1 to 72 탆. As a preferred embodiment of the present invention, it is preferable that the effective width of a circuit composed of repeated lines and meshes is 0.1 to 3 mm in total of the width W of the line and L of the mesh.

3A to 3C are views showing various embodiments of a copper-net circuit structure according to the present invention. FIG. 3A is a view showing a square mesh type copper foil circuit, FIG. 3B is a hexagonal mesh type copper foil circuit, and FIG. 3C is an octagonal mesh type copper foil circuit.

Referring again to FIG. 2C, the mask pattern is transferred to the copper foil 10a by etching the copper foil 10a using the dry film 20 transferred with the pattern as an etching mask. At this time, the copper foil circuit formed by etching is formed into any one of the configurations shown in Figs. 3A to 3C to have transparency. 2D, after the copper foil circuit is formed, the dry film 20 is peeled off.

Although a method of forming a circuit by exemplifying a subtractive process is described above, a circuit pattern may be formed by applying an additive process or a modified semi-additive process (MSAP) Note that it can be formed.

Referring to FIG. 2E, a transparent insulating layer 30 is formed on the copper foil 10a on which the pattern is transferred.

As a first embodiment of the method for forming the transparent insulating layer 30 according to the present invention, a transparent ink or a transparent solder resist (SR) can be applied. The transparent ink is a liquid of urethane or acrylic series. Since the transparent ink formed on the upper surface of the transparent base film 10b is filled with transparent ink and flattened, the light transmittance due to scattering of light is prevented.

As a second embodiment of the method for forming the transparent insulating layer 30 according to the present invention, a transparent coverray (C / L) can be contacted. The transparent coverlay is a material in which a transparent film is coated with a transparent film. The transparent film can be made of the same material as the transparent base film 10b described above, and has good light transmittance (? 80% ), An acrylic resin, an urethane-based resin, a PET-based resin, a PAI-based resin, a polystyrene-based resin, a cyanoacrylate-based resin, or the like can 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 again to FIG. 2E, after the transparent insulating layer 30 is formed by attaching a transparent ink, an adhesive, or a transparent coverlay, the transparent ink is cured by heating, or the transparent insulating layer 30 Laminate. As a preferred embodiment of the present invention, thermosetting can be performed when a transparent solder resist (SR) is applied, and when a transparent coverray (C / L) is contacted, the laminate is laminated by heating and pressing.

The rigid circuit portion can be manufactured only after the transparent flexible circuit portion is manufactured as described above. Referring to FIG. 2F, the prepreg 40 and the copper foil 50 are laminated on the portion where the hard circuit is to be fabricated, and laminated by heating and pressing. At this time, as mentioned above, the transparent base film 10b has high heat resistance and is not warped or deformed.

Referring to FIG. 2G, a via hole 60 is formed through a CNC drilling process or a laser drilling process on a portion where interlayer via-hole connection is required. 2H, copper plating is performed to cover the inner wall of the via hole 60 with copper (Cu) to energize the upper and lower copper foils of the hard circuit portion.

Then, a dry film is coated on the hard circuit area, an image process is carried out, a pattern is transferred to form an etching mask, and the upper and lower copper foils are etched to form a copper foil circuit. 2I is a view showing a state in which solder resist (PSR) 70 is applied on the upper and lower copper circuit circuits. The subsequent process may be a conventional circuit board process such as a finish process, an external process, and an inspection process.

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.

In addition, 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 makes it possible to integrate the flexible circuit part and the general hard circuit part which can be transparent and bent. As a result, it becomes possible to manufacture a head-up display, a head-mounted display or a new concept transparent electronic product.

10a: Copper foil
10b: transparent base film
30: transparent insulating layer
40: Insulating layer
70: Solder resist

Claims (5)

In a circuit board fabricated by integrating a flexible circuit portion and a rigid circuit portion into one,
The flexible circuit unit includes:
A transparent base film;
On the transparent base film, a line having a thickness T and a width W and a mesh having a lanthanum spacing L (W? L) are repeatedly formed. By adjusting the length ratio of L and W, light transmittance and electrical conductivity A first circuit of a regulating net structure;
And a transparent insulating layer formed on an upper surface of the transparent base film so as to cover the circuit, wherein the rigid circuit portion has transparency,
An insulating layer and a conductive layer are laminated on a predetermined area of the upper surface of the transparent insulating layer, and a series of general printed circuit board processes such as photolithography, etching, plating, and via hole processing are performed to transfer a predetermined pattern to the conductive layer The second circuit
Wherein the circuit board comprises: The circuit board of claim 1, wherein the transparent insulation layer comprises any one of cured transparent ink, cured adhesive, or laminated laminated transparent coverlay. A method of manufacturing a circuit board in which a flexible circuit part and a rigid circuit part are integrated into one,
(a) preparing a core substrate on which a first conductive layer is coated on a transparent base film;
(b) a circuit pattern is transferred to the first conductive layer to fabricate a first circuit, wherein the circuit pattern of the first circuit includes a line having a thickness T and a width W and a line having a width L (W? L) Fabricating a first circuit of a net structure that regulates the light transmittance and the electrical conductivity by regulating the length ratio of L and W to the mesh;
(c) forming a transparent insulating layer on the entire surface of the first circuit formed on the upper surface of the transparent base film; And
(d) a second insulating layer and a second conductive layer are stacked on a predetermined region of the upper surface of the transparent insulating layer, and a series of general printed circuit board processes such as photolithography, etching, plating, And transferring a predetermined pattern to the second circuit.
≪ / RTI > 4. The method of claim 3, wherein forming the transparent insulation layer in step (c)
(c1) printing and curing a transparent ink;
(c2) applying and curing a transparent adhesive;
(c3) a step of contacting the transparent coverlay and heat-pressing the laminate,
≪ / RTI > 5. The circuit board manufacturing method according to claim 4, wherein the core substrate on which the first conductive layer is coated on the transparent base film of step (a) comprises a flexible copper clad laminate (FCCL).

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