KR101131584B1

KR101131584B1 - Conductive film for flexible flat cable

Info

Publication number: KR101131584B1
Application number: KR20100026153A
Authority: KR
Inventors: 정준영
Original assignee: 나노인텍 주식회사
Priority date: 2010-03-24
Filing date: 2010-03-24
Publication date: 2012-03-30
Also published as: KR20110107021A

Abstract

The present invention relates to a conductive film for impedance correction and shielding of a flexible flat cable (hereinafter referred to as 'FFC'). According to the present invention, a conductive layer; An adhesive layer for the cable attached to the flexible flat cable; And an insulating layer disposed between the conductive layer and the adhesive layer for the cable.

Description

Conductive film for flexible flat cable {CONDUCTIVE FILM FOR FLEXIBLE FLAT CABLE}

The present invention relates to a conductive film for impedance correction and shielding of a flexible flat cable (hereinafter referred to as 'FFC').

In general, various types of data transmission and reception cables are used in electronic devices. Recently, as the high performance and high functionalization of electronic devices is rapidly progressing, various types of cables suitable for this have been developed and used, and in particular, FFCs having easy bending characteristics are frequently used. Recently, various electronic devices have been developed that realize high-definition image quality, such as high-definition LCD and PDP televisions, notebook computers, or digital scanners, and other electronic devices have also been digitized. It is required.

As the signal transmission speed increases, radiation (Electromagnetic Interference (EMI)), which is unnecessarily generated in the FFC, has become a problem. That is, when the signal is formed at a high frequency due to the high speed of signal transmission, unnecessary radiation noise (propagation) is easily leaked, and when noise is injected into another adjacent cable or the like, causing an adverse effect such as a malfunction or loss of signal transmission. Occurs.

In order to solve the problem of device malfunction and signal transmission loss, the most important is to solve the impedance matching and EMI problems of the FFC, but the conventional FFC cannot solve the impedance matching and EMI problems by itself. Is required.

An object of the present invention is to provide a conductive film for FFC that can be attached to the FFC and can simultaneously solve the problem of impedance matching and EMI of the FFC regardless of the structure of the FFC and the material of the insulator.

In order to achieve the object of the present invention, according to an aspect of the present invention,

Conductive layer; An adhesive layer for the cable attached to the flexible flat cable; And an insulating layer disposed between the conductive layer and the adhesive layer for the cable.

The conductive flat cable for flexible cable further includes an insulator layer support layer positioned between the adhesive layer for the cable and the insulator layer, the insulator layer support layer may be made of polyethylene terephthalate mixed with non-conductive carbon.

The insulating layer may be formed of polypropylene or may be formed of polypropylene or polyethylene having pores.

The conductive film for the flexible flat cable further includes a conductive layer support layer positioned between the conductive layer and the insulating layer, and the conductive layer support layer may be made of polyethylene terephthalate mixed with non-conductive carbon.

The conductive layer may include one or more metals selected from the group consisting of silver, copper, aluminum, and nickel.

The conductive film for the flexible flat cable further includes a protective layer positioned opposite to the adhesive layer for the cable with the conductive layer therebetween, and the protective layer may be made of polyethylene terephthalate mixed with non-conductive carbon.

The flexible flat cable conductive film may further include a primer layer formed between the insulating layer and the adhesive layer for the cable.

According to the present invention, the object of the present invention described above can be achieved. Specifically, since the FFC conductive film including the conductive layer and the insulating layer is easily attached to the FFC, irrespective of the type and structure shape of the insulator of the FFC, it simultaneously solves impedance matching and EMI problems, thereby eliminating signal transmission loss and providing high speed. Enable signal transmission. In addition, since the FFC conductive film according to the present invention is excellent in flexibility, the FFC can maintain its original purpose as it is.

1 is a cross-sectional view showing a laminated structure of a conductive film for FFC according to an embodiment of the present invention.
2 is a cross-sectional view showing another embodiment of the protective layer shown in FIG.
3A and 3B are diagrams showing impedance measurements of sample A. FIG.
4A and 4B are diagrams showing impedance measurements of Sample B. FIG.
5A and 5B are diagrams showing eye pattern measurement values of Sample A. FIG.
6A and 6B are diagrams showing eye pattern measurement values of Sample B. FIG.

In general, FFC requires its own characteristic impedance of 100Ω. However, when the conductor is directly attached to the FFC for the purpose of shielding, the shielding effect can be obtained, but the differential impedance value is significantly lower than the characteristic impedance value, resulting in transmission signal loss.

The conductive film for FFC according to the present invention is based on the thickness and dielectric constant of the insulation of each layer affecting the impedance and the signal transmission speed.

Hereinafter, with reference to the accompanying drawings, it will be described in detail the configuration and operation of one embodiment according to the present invention.

1 is a cross-sectional view showing a laminated structure of a conductive film for FFC according to an embodiment of the present invention. Referring to FIG. 1, the FFC conductive film 100 includes a protective layer 110, a protective layer adhesive layer 120, a conductive layer 130, and a conductive layer support layer, which are sequentially positioned from top to bottom in the drawing. Adhesive layer 140, conductive layer support layer 150, insulating layer adhesive layer 160, insulating layer 170, primer layer 180, insulating layer support layer adhesive layer 182, An insulating layer support layer 185, a cable adhesive layer 190, and a release paper layer 191 are included.

The protective layer 110 prevents electrical contact with other components and protects the conductive layer 130. In this embodiment, the protective layer 110 is a polyethylene terephthalate (PET) mixed with a non-conductive carbon (also referred to as a 'black pigment') having a relatively low dielectric constant of 1.5 to impart impedance stability and light shielding properties. It demonstrates that it consists of a film. 2 shows another embodiment of a protective layer. Referring to FIG. 2, the protective layer 210 includes a PET layer 211 and a nonconductive carbon layer 212. The protective layer 210 may be formed by printing non-conductive carbon on the surface of the PET film 211. In this invention, it is more preferable to use what formed with black pigment embedded in PET as a protective layer rather than using what formed by printing black ink on PET film. In the case of the protective layer 210 that prints black ink on the PET film, since the unprinted portion may be formed on the micro portion, the appearance defect is likely to occur and the thickness of the product increases, but the black pigment is applied to the PET. In the case of the internally formed protective layer 110, the thickness of the product does not increase and the possibility of appearance defects is significantly reduced.

The adhesive layer 120 for the protective layer adheres the protective layer 110 to the conductive layer 130. The adhesive layer 120 for the protective layer may be formed by laminating a double-sided base tape or an inorganic tape on the protective layer 110. Alternatively, the protective layer adhesive layer 120 may be formed of a thermal lamination layer.

The conductive layer 130 functions as a shield material. The conductive layer 130 may include one or more metals selected from the group consisting of silver, copper, aluminum, and nickel. It is preferable that the conductive layer 130 has a surface resistivity of 10 mA / square or less. In addition, it is preferable that the thickness of the conductive layer 130 is 0.01-25 micrometers. The conductive layer 130 may be formed by coating aluminum on the conductive layer support layer 150 by vacuum deposition or by thermally laminating an aluminum thin foil on the conductive layer support layer 150.

The adhesive layer 140 for the conductive layer support layer adheres the conductive layer support layer 150 to the conductive layer 130. The adhesive layer 140 for the conductive layer support layer is formed by dry lamination (hereinafter referred to as 'thermal lamination'). The adhesive layer 140 for the conductive layer support layer may be formed of polyester and an isocyanate curing agent.

The conductive layer support layer 150 supports the conductive layer 130 and functions as an insulating material. In the present embodiment, it will be described that the conductive layer support layer 150 is made of polyethyleneterephthalate. The support layer 150 may be formed to a thickness of 1 to 50㎛ polyethylene terephthalate by extrusion. The conductive layer support layer 150 also serves as an auxiliary layer for correcting fine impedance. The conductive layer support layer 150 may be formed by embedding black pigment in PET. In addition, the conductive layer support layer 150 may be omitted. When the conductive layer support layer 150 is omitted, the conductive layer 130 is directly formed on the insulating layer 170 so that grounding is not required and only impedance matching is required. Can be used.

The adhesive layer 160 for the insulating layer adheres the insulating layer 170 to the support layer 150. The insulating material adhesive layer 140 is formed by thermal paper.

The insulating layer 170 functions as impedance matching (capacitance control). In the present embodiment, as the material of the insulating layer 170, a pure polypropylene (polypropylen) having a very low dielectric constant of 1.5 is used or a polypropylene or polyethylene having fine pores is used. When the micropores are formed, the size of the micropores is preferably 0.1 to 50㎛, the micropores preferably occupy 0.1 to 40% of the entire insulating layer 170. The micropores formed in the insulating layer 170 may be filled with air having a dielectric constant of 1 to further lower the dielectric constant of the insulating layer 170. As the micropores are formed, the composite dielectric constant of the insulating layer 170 is further lowered, which is more advantageous for the capacitance control, and the polypropylene, which is advantageous for the capacitance control because the dielectric constant is lower than the polyethylene, is mainly used in the insulating layer 170, thereby matching impedance. It is advantageous to The insulating layer 170 may be formed to have a thickness of 1 to 100 μm by processing a cross-section corona by extrusion of polypropylene.

The primer layer 180 is provided on the insulating layer 170 so that the insulating layer support layer 185 is easily thermally bonded to the insulating layer 170. The primer layer 180 may include one or more resins selected from the group consisting of acrylic resins, polyester resins, and epoxy resins.

The adhesive layer 182 for the insulating layer support layer adheres the insulating layer support layer 185 to the primer layer 180. The adhesive layer 182 for the insulating layer support layer is formed by thermal paper. The adhesive layer 182 for the insulating layer support layer may be formed of polyester and an isocyanate hardener.

The insulating layer support layer 185 supports the insulating layer 170 and functions as an insulating material. In this embodiment, the insulating layer support layer 185 is described as being made of PET. The insulating layer support layer 185 may be formed to a thickness of 1 to 50㎛ polyethylene terephthalate by extrusion. The insulating layer support layer 185 also serves as an auxiliary layer for correcting fine impedance. The insulating layer support layer 185 may be formed by embedding black pigment in PET. The insulating layer support layer 185 serves to complement the insulating layer 170 having a weak mechanical strength by forming micropores.

The adhesive layer 190 for the cable is an adhesive layer formed to attach the conductive film 100 to the FFC. The adhesive layer 190 for cables may be formed by laminating a double-sided base tape or an inorganic tape on the insulating layer support layer 185. When the adhesive layer 190 for the cable is formed of a tape, the cable adhesive layer 190 may include at least one resin selected from the group consisting of an acrylic resin and a polyethylene terephthalate resin. Unlike this, the adhesive layer 190 for cables may be formed by coating a hot melt on the primer layer 180 using a coating apparatus. When the adhesive layer 190 for the cable is formed of a hot melt, the adhesive layer 190 includes at least one resin selected from the group consisting of a polyurethane resin, an acrylic resin, and a polyethyleneterephthalate resin. Can be. It is preferable that the thickness of the adhesive material layer 190 for cables is 10-100 micrometers. The method of forming the adhesive layer 190 for cables may be appropriately selected according to the working conditions of the FFC to be attached. The adhesive layer 190 for a cable also serves as an auxiliary layer for correcting fine impedance.

The release paper layer 191 is attached to the adhesive layer 190 for the cable and is separated and removed from the adhesive layer 190 for the cable when the conductive film 100 for the FFC is attached to the FFC (not shown).

An example of the manufacturing method for the FFC conductive film 100 of the above embodiment is as follows.

First, a stacked structure of the conductive layer 130 and the conductive layer support layer 150 is formed. It is coated with a conductive material for forming the conductive layer 130 by vacuum deposition on the film forming the conductive layer support layer 150, or a thin foil and conductive layer support layer made of a conductive material for forming the conductive layer 130 ( 150) may be carried out by thermally laminating the film to form.

Next, the insulating layer 170 is thermally laminated to the support layer 150.

Next, the primer layer 180 is formed on the insulating layer 170. The thickness of the insulating layer 170 is arbitrarily set in consideration of characteristic impedance (for example, 100 mA (± 10%)).

Next, the film forming the insulating layer support layer 185 on the primer layer 180 is thermally laminated.

Next, a double-sided base tape or an inorganic tape is attached to the insulating layer support layer 185 or a hot melt is coated to form the adhesive layer 190 for the cable. At this time, the adhesive layer for the cable changes the thickness while measuring the impedance of the FFC (not shown) to correct the differential impedance to finally match the differential impedance.

Next, the protective layer 110 is laminated on the conductive layer 130.

When the FFC conductive film 100 is attached to and used in an FFC (not shown), EMI is effectively blocked by the conductive layer 130 that serves as a shielding action, and may be generated by the conductive layer 130. The sharp drop in the impedance value of the FFC (not shown) is matched by the support layer 150, the insulating layer 170, and the adhesive layer 190 for cables. As the insulating layer 170 is made of a porous polypropylene material which is most effective for impedance matching and capacitance control, the differential impedance of the FFC (not shown) is a valid value (for example, 100 Ω (± 10%). ), Low jitter and clear eye pattern, making it suitable for high-speed transmission of FFC. In addition, since the polypropylene film having a low dielectric constant is used as the insulating layer 170, the overall thickness of the conductive film 100 for FFC can be made significantly thin, thereby maintaining the mobility of the original purpose of the FFC.

The FFC conductive film 100 may be manufactured by appropriately combining the thicknesses of the insulating layer support layer 185 and the insulating layer 170 having an insulating function, the dielectric constant, and the thickness of the adhesive layer 190 for cables, and insulation. The layer 170 is made of polypropylene or polyethylene with low pores of low dielectric constant, or pure polypropylene, and the conductive layer 130 is easy to control the capacitance of the FFC when the aluminum is deposited and the aluminum thin film is used. The product can be manufactured with an impedance of close to 100 Hz. In addition, if the conductive film 100 for the FFC is composed of an appropriate combination based on the insulating layer 170 made of the above-mentioned film, the number of wiring poles, the cable length, and the ground line of the FFC (not shown) may be set. It is also possible to arbitrarily set the wiring arrangement to be included so that the FFC can be applied in any form. The FFC applying the conductive film 100 for FFC is easy to apply to various electronic devices requiring high-speed transmission of signals, such as a liquid crystal monitor system in which a high-precision image is transmitted. Can be avoided.

Hereinafter, the results of measuring the impedance and eye pattern of the FFC by attaching various samples of the conductive film for FFC according to the embodiment of the present invention on the surface of the FFC. After attaching the conductive film for the FFC to the FFC, the differential impedance of the FFC was measured using an Agilent oscilloscope (86100C) and TDR module (54754 A).

First, a test on Sample A and Sample B was conducted. The difference between Sample A and Sample B is the thickness of the insulating layer formed of polypropylene (130 in FIG. 1), wherein the insulating layer of Sample A is about 20 μm thicker than the insulating layer of Sample B, and the thicknesses of the remaining layers are the same. Do. Two measurements were taken for each sample. The impedance measurement result graphs of Sample A are shown in FIGS. 5A and 5B, and the impedance measurement result graphs of Sample B are shown in FIGS. 6A and 6B.

Table 1 below shows impedance measurements for Sample A and Table 2 below shows impedance measurements for Sample B. As shown in Table 1 and Table 2, the differential impedance measurements corresponded to ± 10% for both 100 Ω characteristic impedance. However, if you look closely at the impedance measurements, for sample A with a thicker insulating layer, it was measured in the range of ± 5%, and for sample B, it was measured in the range of ± 10%.

Impedance measurement of sample A Classification FFC 1 FFC 2 Average Measuring impedance Measured value (minimum) 98.8 96.5 97.65 Measured value (maximum) 102.4 101.7 102.05

Impedance measurement of sample B Classification FFC 1 FFC 2 Average Measuring impedance
Measured value (minimum) 90.7 90.6 90.65 Measured value (maximum) 97.2 96.9 97.05

Based on the impedance measurement results, the eye pattern measurement results for Sample A and Sample B are somewhat different. The eye patterns of sample A are shown in FIGS. 7A and 7B, and the eye patterns of sample B are shown in FIGS. 8A and 8B. As shown, the sample A had less jitter and the eye pattern was clearly measured than the sample B. This means that as the value of the differential impedance approaches 100 kHz, the characteristic impedance value, the desired signal value can be transmitted without distortion.

Next, a test was performed on Sample C and Sample D. The difference between Sample C and Sample D is the thickness of the cable adhesive layer (190 in FIG. 1), wherein the cable adhesive layer of Sample C is about 20 μm thinner than the cable adhesive layer of Sample D, and the thickness of the remaining layers is Same as each other. Table 3 below shows impedance measurements for Sample C and Sample D.

Impedance measurements of Samples C and D Classification Sample C Sample D Measuring impedance
Measured value (minimum) 93.8 95.8 Measured value (maximum) 97.4 99.2

The eye pattern of the sample D is clearly displayed as shown in Figs. 7A and 7B. However, the eye pattern of Sample C becomes somewhat unclear, as shown in Figs. 8A and 8B.

Next, a test was performed on sample D. Sample D uses polyethylene instead of polypropylene as the insulating layer (170 in FIG. 1) in the sample, and the other conditions are the same. Table 4 shows the impedance measurements of Sample E.

Classification Sample E Measuring impedance
Measured value (minimum) 99.7 Measured value (maximum) 105.2

As shown in Table 4, the differential impedance of Sample E corresponds to the ideal range value. However, the eye pattern of sample E is unclear. This, in turn, means that the dielectric constants of polypropylene and polyethylene are different so that it is significantly advantageous to use polypropylene with a low dielectric constant in controlling capacitance.

Although the present invention has been described with reference to the above embodiments, the present invention is not limited thereto. The above embodiments may be modified or changed without departing from the spirit and scope of the present invention, and those skilled in the art will recognize that such modifications and changes also belong to the present invention.

100: FFC conductive film 110: protective layer
130: conductive layer 150: conductive layer support layer
170: insulating layer 180: primer layer
185: insulating layer support layer 190: adhesive layer for the cable

Claims

Conductive layer;
An adhesive layer for the cable attached to the flexible flat cable; And
An insulating layer located between the conductive layer and the adhesive layer for the cable;
It comprises a, and further comprising an insulating layer support layer positioned between the adhesive layer for the cable and the insulating layer, wherein the insulating layer support layer is a flexible flat cable, characterized in that made of polyethylene terephthalate mixed with non-conductive carbon For conductive film.

delete

The method according to claim 1,
The insulating layer is a flexible film for flexible flat cable, characterized in that formed of polypropylene.

The method according to claim 1,
The insulating layer is a flexible flat cable conductive film, characterized in that formed of polypropylene or polyethylene with pores.

The method according to claim 1,
And a conductive layer support layer positioned between the conductive layer and the insulating layer, wherein the conductive layer support layer is made of polyethylene terephthalate mixed with non-conductive carbon.

The method according to claim 1,
The conductive layer is a conductive film for a flexible plan cable, characterized in that it comprises at least one metal selected from the group consisting of silver, copper, aluminum, nickel.

The method according to claim 1,
And a protective layer positioned opposite to the adhesive layer for the cable with the conductive layer interposed therebetween, wherein the protective layer is made of polyethylene terephthalate mixed with non-conductive carbon.

The method according to claim 1,
A conductive film for a flexible cable, characterized in that it further comprises a primer layer formed between the insulating layer and the adhesive layer for the cable.