KR101217099B1 - Flexible flat cable - Google Patents

Abstract

PURPOSE: A flexible flat cable is provided to control impedance by controlling line width and line interval of a conducting line. CONSTITUTION: A flexible flat cable comprises a plurality of conducting lines(11), a first insulation film(13), a second insulation film(15), a third insulation film(17), a fourth insulation film(19), and a conductive metal layer(21), and a fifth insulation film(25). The plurality of the conducting lines is formed on the first insulation film. The second insulation film is attached on the first insulation film for covering the plurality of the conducting lines. The first and the second insulation film are formed as heat adhesive property synthetic resin including an insulation property, flexibility, and stability. The third and the fourth insulation film are individually formed on the second and the third insulation film. A conductive metal layer is formed on the fourth insulation film through a photolithography method. The fifth insulation film is formed on the conductive metal layer.

Description

Flexible Flat Cable {Flexible Flat Cable}

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to flexible flat cables, and more particularly, to flexible flat cables, which are used as relay cables for components in electronic device products and the like and in which a plurality of conductors are formed in thin films.

2. Description of the Related Art Generally, in a variety of electronic apparatuses such as a printer, a scanner, a TV, a PC, a notebook, a monitor and a multifunctional apparatus, a flexible flat cable (hereinafter referred to as FFC) is used as a relay cable for electrically connecting components have. Since the FFC is excellent in flexibility, it can be used for moving as flexure. It is used in a wide range of fields because it has a lower manufacturing cost than a flexible printed circuit (FPC) have.

However, the FFC has not conventionally required electrical characteristics such as characteristic impedance. Therefore, it is possible to satisfy the required specifications by simply pressing the insulating film made of synthetic resin on both sides of the FFC through a plurality of conductive wires arranged in parallel at regular intervals so that the conductive metal is formed in the form of conductive wire so that the conductive metal does not come into contact with each other. did.

On the other hand, in recent years, various kinds of electronic apparatuses such as a notebook-type personal computer or a digital scanner that realizes high-definition image quality have been developed, so that a high-speed signal transmission has been required. In addition, as digitization progresses in other electronic apparatus products, it has become a technical problem that speeding up of signal transmission is indispensable.

In general, a signal transmission cable is required to be compatible with high-speed transmission since a signal transmission speed becomes high and a resistance to noise is reduced. However, in such a cable, there is a problem of unnecessary electromagnetic interference (EMI) at the same time as increasing the signal transmission speed. That is, in signal transmission, as the signal becomes a high frequency, unnecessary electromagnetic waves are easily leaked and injected into adjacent cables or the like, which causes adverse effects such as malfunction or transmission loss.

Therefore, the electromagnetic wave was shielded by depositing a shielding layer made of a conductive metal layer on the surface of the insulating film or by adhering a shielding tape.

FFC capable of shielding electromagnetic waves according to the prior art is disclosed in Korean Patent No. 10-0899107 (name of the invention: flexible flat cable).

Flexible flat cable according to the prior art is a plurality of conductive wires formed of a conductive metal arranged in parallel at a predetermined interval so as not to contact with each other and a heat-adhesive synthetic resin to be bonded to each other by laminating through the plurality of conductive wires First and second insulating films formed on one side of the plurality of wires, the first and second insulating films being shorter than the length of the plurality of wires and exposing both ends of the plurality of wires; A third insulating film adhered to one surface of the second insulating film to adjust impedance of the plurality of conductive wires, a fourth insulating film adhered to the surface of the third insulating film, and a surface of the fourth insulating film A conductive metal layer formed of a conductive metal to shield electromagnetic waves, and conductive on the conductive metal layer A conductive anti-oxidation layer formed by coating with a synthetic resin including a metal powder made of an alloy of metal or conductive metals to prevent oxidation while being electrically connected to the conductive metal layer, and formed to be shorter than a length of the first insulating film, so that the conductive And a fifth insulating film covering the anti-oxidation layer so that both ends thereof are exposed in the longitudinal direction to define the ground portion.

In the above-described FFC, a plurality of conductive wires between the first and second insulating films are arranged in parallel at regular intervals such that a conductive metal such as copper or tin is formed in the form of a conductive wire and does not contact each other.

The plurality of conductive wires are interposed between the first insulating film and the second insulating film when the first insulating film and the second insulating film are bonded together. That is, the first and second insulating films are bonded while passing through the joining machines continuously, and the plurality of conductive wires are unwound to have a predetermined interval while being wound on the respective rollers and the like, when the first and second insulating films are joined. It is interposed. Then, the impedance is adjusted by the thickness of the third insulating film.

However, the flexible flat cable according to the prior art has a problem in that the thickness of the insulating film is increased if the impedance is controlled only by the insulating film for controlling the impedance. In addition, there is a problem in that a separate printed circuit board (PCB) or flexible printed circuit board (FPCB) must be connected to each other because the line spacing and line width are not electrically connected between the connectors.

Accordingly, an object of the present invention is to provide a flexible flat cable that can prevent the increase in the thickness of the impedance control insulation film by adjusting the impedance by adjusting the line width and line spacing of the plurality of conductors.

Another object of the present invention is to provide a flexible flat cable that can be electrically connected between connectors having different line spacing and line width without using a separate printed circuit board (PCB) or flexible printed circuit board (FPCB).

A flexible flat cable according to an embodiment of the present invention for achieving the above object is a first interval between the first insulating film and the first insulating film in a predetermined distance so that the middle portion of the line width is narrower than both ends and adjacent to each other. A plurality of conductive wires formed of a thin film of a conductive metal so as to be arranged in parallel with each other, and bonded to cover the plurality of conductive wires on the first insulating film, but having a length shorter than that of the plurality of conductive wires so that both ends thereof are exposed. A second insulation film, a third insulation film formed on the second insulation film to adjust the impedance of the plurality of conductive wires, a fourth insulation film bonded on the third insulation film, and the fourth insulation A conductive metal layer formed of a conductive metal on the surface of the film to shield electromagnetic waves, and formed shorter than a length of the third insulating film; And a fifth insulating film to define a conductive metal layer in the longitudinal direction both ends part is grounded by coating so as to expose.

A flexible flat cable according to another embodiment of the present invention for achieving the above another object is a first insulating film formed so that the other end has a width smaller than one end and the middle portion, and the line width on the first insulating film one side The other side portion and the middle portion is narrower than the end and the plurality of conductors formed of a thin film of conductive metal so that the line spacing is narrower than the other side, and are bonded to cover the plurality of conductors on the first insulating film, A second insulating film having a length shorter than the length of the two conductive wires so that both ends thereof are exposed, a third insulating film formed to be bonded to the second insulating film to control impedance of the plurality of conductive wires, and the third insulating film; A fourth insulating film bonded to the insulating film and a conductive metal formed on the surface of the fourth insulating film to shield electromagnetic waves It is formed shorter than the metal layer and the length of the fourth insulating film and a fifth insulating film for covering limited parts of the ground so that the both ends expose the conductive metal layer in the longitudinal direction.

In the above, a plurality of conductors are formed by vapor deposition or plating, and the plurality of conductors are formed by a lift-off method or a photolithography method.

The plurality of conductive wires are formed by attaching a foil of a conductive metal on the fourth insulating film and patterning the same by a photolithography method.

In the above, the first, second, third, fourth and fifth insulating film is nylon (nylon), polyimide (polyimide), polyvinylacetate, polyurethane (polyurethane), polyester (polyester), polyethylene It is formed of synthetic resin of (polyethylene) or polypropylene (polypropylene).

Therefore, the present invention has an advantage of preventing the increase in the thickness of the impedance control insulation film because the impedance is adjusted by changing the line width and line spacing of the plurality of conductors. In addition, since the line widths and line spacings of the plurality of conductors can be changed, there is an advantage that the line widths and the line widths can be easily electrically connected between connectors having different line spacings and line widths without using a separate PCB or FPCB.

1 is a plan view partially cut a flexible flat cable according to an embodiment of the present invention.
2 is a cross-sectional view taken along the line AA of FIG.
3 is a plan view showing a plurality of conductive wires disposed on the first insulating film according to another embodiment of the present invention.

Hereinafter, with reference to the accompanying drawings will be described in detail the present invention.

1 is a plan view partially cut a flexible flat cable according to an embodiment of the present invention, Figure 2 is a cross-sectional view taken along the line A-A.

In the flexible flat cable according to the embodiment of the present invention, the plurality of conductive wires 11, the first and second insulating films 13 and 15, the third insulating film 17, the fourth insulating film 19, and the conductive metal layer 21 and the fifth insulating film 25.

A plurality of conductive wires 11 are formed of a conductive metal such as aluminum, copper, or tin on the first insulating film 13. The plurality of conductive lines 11 are formed to be arranged in parallel at regular intervals so as not to contact each other with the adjacent ones by a method such as deposition or plating. It is narrower than the end and formed narrow. In the above, the middle portion of the plurality of conductive lines 11 increases the line spacing while decreasing the line width, and the decrease of the line width and the increase of the line spacing respectively increase the impedance.

In the above, both ends of the plurality of conductive wires 11 are electrically connected by being coupled to connectors of other components. Therefore, both ends of the plurality of conductive wires 11 must correspond to the line width and line spacing of the connector of the other component to be joined and cannot be arbitrarily changed. Accordingly, the plurality of conductive lines 11 increases the line spacing while increasing the impedance while reducing the line width of the intermediate portion transmitting the signal without changing the line width and the line spacing at both ends.

The plurality of conductive wires 11 may be formed by forming a release layer on the first insulating film 13 to expose a portion where the conductive wire is to be formed, and removing the release layer after deposition or plating.

In addition, the plurality of conductive wires 11 may be formed by depositing or plating a metal to form the conductive wire on the first insulating film 13 and then patterning the same by a photolithography method. In addition, the plurality of conductive wires 11 may be formed by attaching a foil to form a conductive wire on the first insulating film 13 with an adhesive or an adhesive and then patterning the photolithography method.

In the above, the plurality of conductive wires 11 may be plated with Ni / Au, Ni, Sn, or the like at both ends in the longitudinal direction, and may be oxidized while improving conductivity to prevent an increase in resistance.

The second insulating film 15 is bonded onto the first insulating film 13 to cover the plurality of conductive wires 11. The first insulating film 13 is the same as the length of the conductive wire 11 and the second insulating film 15 is formed shorter than the length of the plurality of conductive wires 11 so that both ends of the conductive wire 11 in the longitudinal direction Expose

The first and second insulating films 13 and 15 are formed of a heat-adhesive synthetic resin having insulation, heat resistance, flexibility, and resilience while having mechanical strength such as tensile strength, and have a thickness of about 10 to 250 μm. . Therefore, the first and second insulating films 13 and 15 may be made of nylon, polyimide, polyvinylacetate, polyurethane, polyester, and polyethylene. Or it may be formed of a synthetic resin such as polypropylene.

The third insulating film 17 is formed on the second insulating film 15 and the fourth insulating film 19 is formed on the third insulating film 17 by bonding with an adhesive or an adhesive. In the above, the third insulating film 17 is used as a dielectric layer to increase the impedance to match the impedance of the plurality of conductors 11 to prevent transmission loss due to the reduction of capacitance. Is formed to expose both ends of the plurality of conductive wires 11 in the longitudinal direction.

The third and fourth insulating films 17 and 19 may be nylon, polyimide, polyvinylacetate, and poly like the first and second insulating films 13 and 15. It may be formed of a synthetic resin such as urethane (polyurethane), polyester (polyester), polyethylene (polyethylene) or polypropylene (polypropylene). In addition, the fourth insulating film 19 is firmly adhered to the interlayer using an adhesive such as polyurethane, polyester, polyvinylacetate copolymer, polyvinyl acetate copolymer, acrylic copolymer, etc. on the third insulating film 17. To attach. In addition, the fourth insulating film 19 may be attached onto the third insulating film 17 with an adhesive such as acrylic, polyurethane, or silicone.

The third insulating film 17 may match the impedance even if the thickness is reduced by increasing the line spacing while increasing the line spacing of the middle portions of the plurality of conductive lines 11. Therefore, since the thickness of the third insulating film 17 is reduced, it is possible to reduce the overall thickness of the flexible flat cable.

In addition, the fourth insulating film 19 is made of a conductive metal such as aluminum, silver, gold, copper, nickel, molybdenum, nickel, or tin, which is generated from the conductive wire 11 during signal transmission and radiated to the outside or the conductive wire from the outside ( The conductive metal layer 21 for shielding the electromagnetic wave applied to 11) is formed to a thickness of about 100 to 50 µm.

The conductive metal layer 21 is formed on the fourth insulating film 19 to expose a release layer (not shown) to expose the portion where the conductive metal layer is to be formed, and after the conductive metal is deposited or plated, the release layer is removed. Method, that is, by a lift-off method.

In addition, the conductive metal layer 21 may be formed by a photolithography method in which a conductive metal is deposited or plated on the fourth insulating film 19 and then patterned.

As the method of depositing the conductive metal layer 21, a deposition method such as evaporation, chemical vapor deposition (CVD) or physical vapor deposition (PVD) may be used.

In addition, the conductive metal layer 21 may be formed by bonding a foil of the conductive metal on the fourth insulating film 19 with an adhesive or an adhesive and then patterning the photolithography method.

In addition, the conductive metal layer 21 may be formed on the fourth insulating film 19 by using a printing method such as silk screen, conductive ink or conductive pate containing powder of the conductive metal.

In the case where the conductive metal layer 21 is formed by a deposition or plating method, a polyurethane-based resin, a polyester-based resin, or an acrylic to facilitate deposition or plating between the fourth insulating film 19 and A primer layer coated with a synthetic resin such as an (acryl) resin and a vinyl resin may be formed.

In addition, when the conductive metal layer 21 is formed by a deposition or plating method, a conductive antioxidant layer may be formed on the conductive metal layer 21. The conductive antioxidant layer prevents the metal layer 21 from being exposed to air and oxidized, and includes a conductive powder such as aluminum, gold, silver, copper, or nickel, or a metal powder made of an alloy of these metals. Synthetic resins such as (polyurethane), polyester (polyester), acrylic (acryl) or polyvinyl (vinyl) may be formed by a method such as coating.

Like the first and second insulating films 13 and 15, the fifth insulating film 25 may be made of nylon, polyimide, polyvinylacetate, polyurethane, and polyester ( A synthetic resin such as polyester, polyethylene, or polypropylene is formed on the conductive metal layer 21 to a thin thickness of about 10 to 50 μm. The fifth insulating film 25 is formed to be shorter than the length of the second insulating film 15 so that both ends of the conductive metal layer 21 are exposed in the longitudinal direction. The portion exposed without being covered by the fifth insulating film 25 at both ends of the conductive metal layer 21 becomes the ground portion 27.

As described above, in the flat cable according to the embodiment of the present invention, both ends coupled to the connectors of the other parts of the plurality of conductors 11 have a line of an intermediate portion for transmitting signals without changing the line width and line spacing. You can increase the impedance by increasing the line spacing while decreasing the width. Therefore, it is possible to prevent the thickness of the third insulation film 17 for impedance adjustment from increasing.

3 is a plan view illustrating a plurality of conductive wires disposed on a first insulating film according to another exemplary embodiment of the present invention.

In the flexible flat cable according to another embodiment of the present invention, a plurality of conductive wires 11 are disposed when line widths and line spacings of both connectors (not shown) to which both ends are coupled are different. That is, in the flexible flat cable, a plurality of conductive wires 11 are arranged such that one end of a large line width is coupled with a connector having a large line width and the other end of the small line width is coupled with a connector having a small line width. Therefore, in the flexible flat cable, the other end has a smaller width than the one end, so the first insulation film 13 also has the other end smaller than the one end and the middle part.

The plurality of conductive wires 11 are adjacent to each other on the first insulating film 13 by a conductive metal such as aluminum, silver, gold, copper, molybdenum, nickel or tin by a conductive metal such as vapor deposition or plating. It is formed to be arranged in parallel at regular intervals so as not to contact each other. In the above, the plurality of conductive wires 11 are formed such that a portion coupled with the connector having a large line width at one end thereof has a large line width and the other portions have a reduced line width. In addition, since the other end of the first insulating film 13 has a width smaller than the other end and the other end, the plurality of conductive wires 11 are symmetrically bent to the middle part in the narrower portion, thereby narrowing the narrow line interval. It is formed to have.

The plurality of conductive wires 11 may be formed by forming a release layer on the first insulating film 13 to expose a portion where the conductive wire is to be formed, and removing the release layer after deposition or plating.

In addition, the plurality of conductive wires 11 may be formed by depositing or plating a metal to form the conductive wire on the first insulating film 13 and then patterning the same by a photolithography method. In addition, the plurality of conductive wires 11 adhere a foil of a conductive metal such as aluminum, silver, gold, copper, molybdenum, nickel or tin to form a conductive wire on the first insulating film 13 with an adhesive or an adhesive. It may then be formed by patterning by a photolithographic method.

In the above, the plurality of conductive wires 11 may be plated with Ni / Au, Ni, Sn, or the like at both ends in the longitudinal direction, and may be oxidized while improving conductivity to prevent an increase in resistance.

Although not shown in FIG. 2, a second insulating film, a third insulating film, a fourth insulating film, a conductive metal layer, and a fifth insulating film are formed on the first insulating film 13 to cover the plurality of conductive wires 11. Can be.

Since the plurality of conductive lines 11 are easily changed in line width and line spacing, the plurality of conductive lines 11 may be easily electrically connected between connectors having different line spacing and line width without using a separate PCB or FPCB.

In addition, the flexible flat cable according to another embodiment of the present invention is a plurality of conductive wires on the first insulating film when the line width and the line spacing of both connectors to which both ends are respectively coupled, as in another embodiment of the present invention The middle portion is formed in a straight line shape, and the remaining both sides may be formed in a straight line shape so that the line spacing gradually narrows from one side to the other side.

In addition, the flexible flat cable according to another embodiment of the present invention can adjust the impedance value required by adjusting the line width and line spacing of each of the plurality of conductors. In addition, the plurality of conductive lines may have a form of a straight line, a curve, or a waveform.

As described above, the present invention is merely an embodiment, and the present invention is not limited to the above-described embodiments, and various modifications may be made by those skilled in the art within the technical spirit of the present invention. .

11: Lead wire 13, 15: 1st and 2nd insulating film
17: third insulating film 19: fourth insulating film
21 conductive metal layer 25 fifth insulating film
27: grounding part

Claims (7)

A first insulating film,
A plurality of conductive wires formed of a thin film of a conductive metal such that a line width is narrower than both ends on the first insulating film and arranged in parallel at a predetermined interval so as not to be in contact with adjacent ones;
A second insulating film bonded to the plurality of conductive wires on the first insulating film but having a length shorter than the length of the plurality of conductive wires so that both ends thereof are exposed;
A third insulating film formed to be bonded to the second insulating film to adjust impedance of the plurality of conductive wires;
A fourth insulating film bonded to the third insulating film,
A conductive metal layer formed of a conductive metal on the surface of the fourth insulating film to shield electromagnetic waves;
And a fifth insulating film formed shorter than the length of the fourth insulating film to cover the conductive metal layer so that both ends thereof are exposed in the longitudinal direction to define a grounding part.
The flexible flat cable of claim 1, wherein the plurality of conductors are formed by deposition or plating.
The flexible flat cable of claim 2, wherein the plurality of conductors are formed of a conductive metal by a lift-off method.
The flexible flat cable of claim 2, wherein the plurality of conductive wires are formed of a conductive metal by a photolithography method.
The flexible flat cable of claim 1, wherein the plurality of conductive wires are formed by attaching a foil of a conductive metal on the fourth insulating film and patterning the same by a photolithography method.
The method according to claim 1, wherein the first, second, third, fourth and fifth insulating film is nylon, polyimide, polyvinylacetate, polyurethane, polyester ), Flexible flat cable formed of synthetic resin of polyethylene or polypropylene. A first insulating film formed so that the other end has a width smaller than the one end and the middle part;
A plurality of conductive wires formed of a thin film of a conductive metal such that the line width is narrower on one side than the one end and the middle part on the first insulating film, and the line spacing is narrower on the other side than one side;
A second insulating film bonded to the plurality of conductive wires on the first insulating film but having a length shorter than the length of the plurality of conductive wires so that both ends thereof are exposed;
A third insulating film formed to be bonded to the second insulating film to adjust impedance of the plurality of conductive wires;
A fourth insulating film bonded to the third insulating film,
A conductive metal layer formed of a conductive metal on the surface of the fourth insulating film to shield electromagnetic waves;
And a fifth insulating film formed shorter than the length of the third insulating film to cover the conductive metal layer so that both ends thereof are exposed in the longitudinal direction to define a ground portion.

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