Composite flexible circuit planar cable

A composite flexible circuit planar cable includes a flat cable, a first section, and a second section. The flat cable includes a plurality of straight line like parallel and non-jumping conductor lines. At least one jumping line is formed on the first section to interchangeably connect a selected conductive line of the first section to an another selected conductive line. The second section may also form at least one jumping line to interchangeably connect a selected conductive line of the second section to an another selected conductive line. Through such a jumping line, electrical connection can be formed between signal terminals and corresponding and interchanged signal terminals. The plurality of conductor lines of the flat cable includes at least a pair of differential signal conductor lines, a grounding line, and a power line.

BACKGROUND OF THE INVENTION

1. Field of the Invention

The present invention relates to a circuit flat cable, and in particular to a composite flexible circuit planar cable that combines a regular flexible planar cable, such as a flexible flat ribbon cable that is often referred to as flexible flat cable, and a regular circuit board.

2. The Related Arts

Processes for manufacturing a flexible circuit board are often classified as (1) forming a flexible board through image transfer, etching conductive layer, and laminating insulation layer, (2) directly printing conducive layer on a flexible board of insulation base material, and (3) forming a standard planar cable by stretching a plurality of parallel straight copper wires with a wind-up machine and laminating insulation layer. Dividing by functionality, there can be carrier boards, planar cables, or flexible circuit board featuring the functions of both carrying board and planar cable. Thus, a flexible circuit board is also referred to in different terms, such as flexible printed circuit board and flexible flat cable. These terms are actually directed to the same product. Based on the classification made according to manufacturing cost, a flexible board made through etching is the most expensive one and printing is the next expensive one, and the standard flexible flat cable is the cheapest one.

With increasing competition and mass production, to further reducing the manufacturing cost, the designs of internal components must be increasingly simplified. And, interconnection between modules can be done with a flexible flat cable to provide a path for signal transmission, and more importantly, to lower down the cost. However, the regular flexible flat cable often generates high frequency and high energy electromagnetic waves when transmitting signals, and also, the signal transmitted by the cable is easily subjected to interference caused by external high frequency noises, leading to distortion of the signal. Further, a flexible flat cable or a circuit board, when extending through a hole that is often put in movement, may generate high voltage static electricity. Under such a condition, fast and effective grounding is very vital.

To handle such drawbacks, a known solution is to coating a metal shielding layer on a surface of the flexible circuit board to shield external electromagnetic noises. However, such a metal shielding layer is effective in isolating the interference caused by external electromagnetic noises, but the metal shielding layer so coated is not effectively connected to ground of an electronic device, so that the performance of the metal shielding layer in shielding electromagnetic noises and eliminating static electricity is not good enough.

Thus, internal modules of a conventional electronic device often commonly use a conventional flexible circuit board made with an etching process as signal connection for easy grounding. However, the cost of the conventional flexible circuit board is much higher than the standard flexible flat cable. Further, one of the reasons that the standard flexible flat cable does not possess the function of electromagnetic noise shielding is that the manufacturing process is carried out by stretching and laminating copper wires so that the copper wires are of small width, making it difficult to control the impedance thereof. Thus, it is a major challenge for the industry to use regular flexible flat cable to replace the usage area of a fraction of the conventional flexible circuit board for reduction of cost and to provide effective shielding against electromagnetic noise and to provide impedance control for signal, and at the same time featuring a conductive connection structure for elimination of static electricity. Further, in some product applications, extension is made through a small hole or a bore of a hinge and tens of thousands of times of tests must be passed for bending durability. This is no exemption for applications of bundle like structure that is formed by partial slitting.

In addition, in an attempt of applying interconnection formed with standard flexible flat cable to provide a path for signal transmission for the purposes of lowering cost, when the positions of the corresponding signal terminals of the modules to be connected are different from each other, electrical connection will not be established between the positions of signal terminals and the positions of corresponding signal terminals.

SUMMARY OF THE INVENTION

To effectively overcome the previously discussed drawbacks, an object of the present invention is to provide a composite flexible circuit cable that combines a standard flexible flat cable and a conventionally etching-made circuit board.

Another object of the present invention is to provide a circuit flat cable that has wide applications, wherein a circuit board included is a rigid circuit board, a flexible circuit board, or a rigid-flex board. For a standard flexible flat cable or a flexible circuit board used, for easy extension through a small hole or a hinge bore, multiple slits may be made among signal lines for overlapping or being arranged in a bundle-like structure, so as to allow the standard flexible flat cable to easily extend a small hole or a hinge bore in an application and to allow of interchange of wires.

To achieve the above objects, the present invention provides a composite flexible circuit planar cable, which comprises a flat cable, a first section, and a second section. The flat cable comprises a plurality of straight line like parallel and non-jumping conductor lines.

The first section comprise a flat cable connection end, an external connection end, and a plurality of conductive lines extending and laid between the flat cable connection end and the external connection end. The flat cable connection end is connected to the first end of the flat cable and electrically connected to the conductor lines extending to the first end of the flat cable.

The first section may comprise at least one jumping line, which is formed on the first section. The jumping line interchangeably connects a selected conductive line of the first section to an another selected conductive line.

The second section comprises a flat cable connection end, an external connection end, and a plurality of conductive lines extending and laid between the flat cable connection end and the external connection end. The flat cable connection end is connected to the second end of the flat cable and electrically connected to the conductor lines extending to the second end of the flat cable.

The second section may also comprise at least one second jumping line, which is formed on the second section. The second jumping line interchangeably connects a selected conductive line of the second section to an another selected conductive line.

Further, the circuit board has two ends that are provided with corresponding but interchange signal terminals, whereby with a jumping line provided on the circuit board, electrical connection can be established between signal terminals and corresponding but interchanged signal terminals.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

With reference to the drawings and in particular toFIGS. 1 and 2,FIG. 1is a perspective view showing a flat cable and first and second sections according to a first embodiment of the present invention in a separate manner andFIG. 2is a perspective view showing the flat cable and the first and second sections according to the first embodiment of the present invention in an assembled form. As shown in the drawings, the present invention provides a composite flexible circuit planar cable, which comprises a flat cable1, a first section2, and a second section3.

The flat cable1has a first end11and a second end12and a plurality of straight line like parallel and non-jumping conductor lines13extending in a flat cable extension direction11between the first end11and the second end12. The conductor lines13include at least a pair of differential signal conductor lines S11, S12, at least one grounding line13G, and a power line13P.

The first section2has a flat cable connection end21, an external connection end22, and a plurality of conductive lines23extending and laid between the flat cable connection end21and the external connection end22. The flat cable connection end21of the first section2is connected to the first end11of the flat cable1and is electrically connected to the plurality of conductor lines13that extends to the first end11of the flat cable1. The plurality of conductive lines23includes at least conductive line serving as a first grounding conductive line23G, at least a pair of first differential signal lines S21, S22, and a first power line23P. The first grounding conductive line23G is electrically connected to the grounding line13G of the flat cable1. The first differential signal lines S21, S22are electrically connected to the differential signal conductor lines S11, S12of the flat cable1. The first power line23P is electrically connected to the power line13P of the flat cable1. The first section2can be one of a single-sided circuit board, a double-sided circuit board, and a multilayer circuit board.

The second section3has a flat cable connection end31, an external connection end32, and a plurality of conductive lines33extending and laid between the flat cable connection end31and the external connection end32. The flat cable connection end31of the second section3is connected to the second end12of the flat cable1and is electrically connected to the plurality of conductor lines13extending to the second end12of the flat cable1. The plurality of conductive lines33includes at least conductive lines serving as a third grounding conductive line33G, at least a pair of second differential signal lines S31, S32, and the second power line33P. The third grounding conductive lines33G is electrically connected to the grounding line13G of the flat cable1. The second differential signal lines S31, S32are electrically connected to the differential signal conductor lines S11, S12of the flat cable1. The second power line33P is electrically connected to the power line13P of the flat cable1. The second section3can be one of a single-sided circuit board, a double-sided circuit board, and a multilayer circuit board.

Referring toFIGS. 3 and 4,FIG. 3is a cross-sectional view showing the structure of the first section that has an upper surface covered with a shielding layer andFIG. 4is a cross-sectional view showing the structure of the first section that has an upper surface and a lower surface both covered with a shielding layer. As shown in the drawings, the flat cable1may further comprise an upper insulation layer14and a lower insulation layer15. The upper insulation layer14and the lower insulation layer15are respectively formed on the upper surface and the lower surface of plurality of straight line like parallel and non-jumping conductor lines13. The upper insulation layer14and the lower insulation layer15can be made of a material selected from insulation materials of PET (Polyethylene Terephthalate) or PI (Polyimide).

The first section2will be taken as an example for further explanation. In consideration of transmission performance of signal and reduction of interference during the transmission of signal, an upper shielding layer41(as shown inFIG. 3) may be set to cover the upper surface212of the circuit board211and the conductive lines23, if desired, or alternatively, an upper shielding layer41and a lower shielding layer42are set to respectively cover the upper surface212of the circuit board211and the conductive lines23and the lower surface213. It is certainly feasible to only cover the lower surface213of the circuit board211with a lower shielding layer42if desired.

Referring toFIGS. 5 and 6,FIG. 5is a schematic view showing a first embodiment according to the present invention andFIG. 6is a cross-sectional view taken along line6-6ofFIG. 5. Both the first section and the second section are single-sided boards. The first section2is taken as an example for explanation. The conductive lines23are laid on the circuit board211. The upper surface of the conductive lines23is covered with an insulation layer24. The insulation layer24forms a hole structure H1at a location corresponding to the first grounding conductive line23G and a hole structure H2corresponding to the second grounding conductive line23G′.

In a second embodiment according to the present invention, besides the first grounding conductive line23G of the first section2is electrically connected to the grounding line13G of the flat cable1, the first grounding conductive line23G of the first section2(which is defined herein as a “selected conductive line”) is connected via a jumping line25to the second grounding conductive line23G′ (which is defined herein as “another selected conductive line”). The third grounding conductive line33G of the second section3is electrically connected to the grounding line13G of the flat cable1. As shown inFIG. 6, the jumping line25is formed by applying sliver slurry coated wiring to the insulation layer24for interchangeably connecting the first grounding conductive lines23G (the selected conductive line) to the second grounding conductive line23G′ (the another selected conductive line) and covered with a cover layer26.

Referring toFIG. 7, a schematic view of a second embodiment of the present invention is shown. As shown in the drawing, in the second embodiment of the present invention, the first differential signal lines S21, S22of the first section2are electrically connected to the differential signal conductor lines S11, S12of the flat cable1. The first differential signal lines S21, S22(selected conductive lines) are respectively interchangeably connected via jumping lines251,252to the first differential signal lines S21′, S22′ (another selected conductive lines). The second differential signal lines S31, S32of the second section3are electrically connected to the differential signal conductor lines S11, S12of the flat cable1. This arrangement is applied to the situation where the positions of signal terminals of the first section2and the second section3do not correspond to each other and the jumping lines251,252are useful to make the signals of the first section2jumping to another designated position of signal terminal.

Referring toFIGS. 8-10,FIG. 8is a top plan view showing a third embodiment according to the present invention;FIG. 9is a rear view of the third embodiment of the present invention; andFIG. 10is a cross-sectional view taken along line10-10ofFIG. 8. Both the first section and the second section are double-sided boards. The first section2will be taken as an example for explanation. Upper wiring23A is formed on an upper surface of a circuit board211and an upper insulation layer24A is formed on a surface of the upper wiring23A. Lower wiring23B is formed on a lower surface of the circuit board211and a lower insulation layer24B is formed on a surface of the lower wiring23B.

The first section2comprises at least a via hole5extending in a perpendicular direction12through the upper insulation layer24A, a first grounding conductive line23G of the upper wiring23A, the circuit board211, a second grounding conductive line23G′ of the lower wiring23B, the lower insulation layer24B, and the lower conductor layer44and forming a hole wall structure51. A conductive cover section6is set to cover the hole wall structure51of the via hole5.

The first grounding conductive lines23G of the upper wiring23A and the second grounding conductive line23G′ of the lower wiring23B are set in electrical connection with each other through the conductive cover section6of the via hole5. The via hole5may realize jumping of conductive lines and the jumping helps improving utilization of electrical connection. The conductive cover section6can be formed with a process including coating of dry film, exposure, development, and etchings. The conductive material used for the conductive cover section6can be selected from copper, silver, gold, and a combination thereof.

In the third embodiment of the present invention, besides the first grounding conductive line23G of the first section2being electrically connected to the grounding line13G of the flat cable1, the first grounding conductive line23G of the first section2(the selected conductive line) is also interchangeably connected, through jumping via the via hole5, to the second grounding conductive line23G′ (the another selected conductive line). The second grounding conductive line33G of the second section3is electrically connected to the grounding line13G of the flat cable1.

Referring toFIGS. 11-13,FIG. 11is a schematic view showing the flat cable is slit to form a plurality of slit lines;FIG. 12is a schematic view showing the flat cable is slit and stacked; andFIG. 13is a schematic view showing the flat cable is slit and bundled. The flat cable1can be slit along intervals between the conductor lines13to form a plurality of slit lines16. Separation is then made of the plurality of conductor lines to form a plurality of conductor line segments. At least one tear protection hole7is formed at one end of the slit lines16. The tear protection hole7functions to prevent undesired tearing of the flat cable.

The plurality of conductor line segments can be stacked to form a bundle structure17(as shown inFIG. 12), or alternatively, the plurality of conductor line segments, after being arranged in a bundle structure17, can be wrapped with a wrapping member8(as shown inFIG. 13) in order to reduce the area of the flat cable. Besides improving design flexibility of circuit board, this also helps extending through a bore91of a hinge structure9or a small hole (not shown).

Referring toFIGS. 14 and 15,FIG. 14is a schematic view showing a third embodiment according to the present invention andFIG. 15is a schematic view showing a folded condition of the third embodiment according to the present invention. The first section2has a flat cable connection end21and a plugging end22that are perpendicular to each other. The second section3has a flat cable connection end31and an external connection end32that are perpendicular to each other.

At least one fold line L is formed along the extension direction I1of the flat cable1and extends through the flat cable1, the first section2, and the second section3. At least one slit line16is formed along the fold line L and extends between the interfaces between the flat cable1and the first and second sections2,3. The fold line L and the slit line16allow the flat cable1, the first section2, and the second section3of the second embodiment to be stacked in a size-reduced structure (as shown inFIG. 15) so that the area occupied by the flat cable in a circuit design can be reduced. Further, this allows the flat cable to extend through a small hole a bore of a hinge structure.

Referring to16, a schematic view showing a fourth embodiment according to the present invention is given. As shown in the drawing, the first section2has a flat cable connection end21and a plugging end22that are perpendicular to each other. The second section3has a flat cable connection end31and an external connection end32that are perpendicular to each other. The external connection end22of the first section2and the external connection end32of the second section3are set in opposite directions. In a practical application, the external connection end22of the first section2and the external connection end32of the second section3can be external connection terminals, insertion slots, connectors, soldering terminals, electronic components, or surface mounting components for connection with an external device (such as a main board of electronic device and liquid crystal display device).

It can be appreciated from the above description that the present invention provides a composite flexible circuit planar cable, which comprises a flat cable, a first section, and a second section, wherein the flat cable is a commercially available standard flexible flat cable and the first section and the second section can be selected from one of single-sided boards, double-sided board, and multilayer boards.

The present invention provides the following advantages:

(1) A standard flexible flat cable is provided for effecting signal connection sot that as compared to an arrangement that uses a flexible circuit board for transmission of signal, the present invention allows of reduction of manufacturing cost of electronic device.

(2) The present invention provides a shielding layer selectively covering the upper surface and the lower surface of the first section and the second section so as to provide improved electromagnetic shielding and elimination of static electricity.

(3) The present invention provides a combined flat cable structure of a bundle like standard flexible flat cable and a circuit board for wire extension through a hinge of an electronic device.

(4) The present invention provides the first section and the second section in such a way that the flat cable connection end and the external connection end arc pointing at different or identical directions so that a combined flat cable structure of a flexible flat cable and circuit board that uses such circuit boards provides line extension arrangement of multiple directions and a more appropriate use of space. Further, via hole technology may be used for wire jumping of conductor lines.

(5) The present invention provides a wire jumping arrangement, which comprises silver plate printing or a via hole that form in the first section or the second section a jumping line to interchangeably connect lines to proper positions of terminals thereby improving utilization of circuit connection.