KR100880182B1 - Flexible printed circuit board of large capacity signal transmission medium - Google Patents

Abstract

A flexible printed circuit board for a large capacity signal transmission medium is provided to maintain constant signal transmission quality by maintaining impedance for transmitting the signal with the large capacity. A copper foil signal wiring(310) receives the signal with the large capacity from the TV main board and transmits the signal to a display device. A copper foil ground layer(320) grounds the signal with the large capacity returned from the display device. An insulating layer(330) is adhered between the copper foil signal wiring and the copper foil grounding layer. A first pad(312) and a second pad(314) of the copper foil signal wiring have the width of 80 to 110 um range. The thickness of the first pad and the second pad of the copper foil signal wiring and the copper foil ground layer is 30 to 40 um range. The thickness of the insulating layer has 20 to 30 um range.

Description

Flexible printed circuit board of large capacity signal transmission medium

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to printed circuit boards and, more particularly, to flexible printed circuit boards used as a medium for transmitting large signals such as low-volage differential signaling (LVDS).

Currently, digital TVs can view images through an LCD panel or a PDP panel. Digital TV mainly uses LCD or PDP for display. In order to reduce the thickness of TV products, PCB thickness needs to be slim and flexible structure is needed due to the large size of TV. 1 is a diagram illustrating a conventional flexible flat cable (FFC) for a LVDS signal transmission medium applied to the digital TV structure shown. Such a conventional FFC for LVDS signal transmission medium is easy to manufacture, but difficult to automate, ie, many manual operations, lack of LVDS signal transmission capability, problems with EMC, and poor quality and long-term use due to manual operation. As it is about 1000 ㎛, it is difficult to use for thin products and automation of production is difficult.

SUMMARY OF THE INVENTION The present invention has been made in view of the above-described problems, and an object thereof is to provide a flexible printed circuit board for a high-capacity signal transmission medium having excellent flexibility while maintaining an impedance suitable for accurately transmitting a high-capacity signal such as LVDS. have.

In order to achieve the above object, in the flexible printed circuit board for a high-capacity signal transmission medium according to the present invention, a first pad having a positive phase and a second pad having a negative phase are alternately spaced at regular intervals and alternately arranged in pairs. Copper large-capacity signal wiring for receiving a large-capacity signal from the TV main board and transmitting the large-capacity signal to the display device; A copper foil grounding layer attached to the copper foil large-capacity signal line at a distance to ground the large-capacity signal transmitted to the display device and returned; And an insulating layer adhered between the copper foil high-capacity signal wire and the copper foil ground layer to maintain a constant distance between the copper foil high-capacity signal wire and the copper foil ground layer. The first pad and the second pad of the copper foil high-capacity signal wiring have a width in the range of 80 to 110 μm so that the two pads are controlled to an impedance of 80-110 Ω, And the thickness of the copper foil ground layer each has a range of 30 to 40 μm, and the thickness of the insulating layer has a range of 20 to 30 μm.

Advantageously, said large-capacity signal comprises an LVDS signal and said insulating layer is formed by polyimide having a dielectric constant of 2.7.

More preferably, the flexible printed circuit board for a high-capacity signal transmission medium may include a first adhesive layer having a thickness of 5 to 15 μm that bonds the first pad and the second pad of the copper foil high-capacity signal wiring to the insulating layer using a first adhesive; A second adhesive layer having a thickness of 5 to 15 μm that bonds the copper foil ground layer and the insulating layer with a second adhesive; And a copper foil power wire having a thickness of 30 to 40 μm attached at a distance from one of the first pad and the second pad of the copper foil large-capacity signal wire. A third adhesive layer having a thickness of 20 to 30 μm laminated on the first adhesive layer to cover the copper foil high capacity signal wire and the copper foil power wire: 7 to 17 μm thick attached to the third adhesive layer to protect the copper foil high capacity signal wire A first coverlay layer; A fourth adhesive layer having a thickness of 20 to 30 μm applied to the surface of the copper foil ground layer; And a second coverlay layer having a thickness of 7 to 17 μm attached to the fourth adhesive layer to protect the copper foil ground layer, wherein the total thickness is in the range of 174 to 274 μm.

According to the present invention, excellent LVDS signal transmission performance and flexibility, various shapes of FPCB can be manufactured, excellent heat resistance, low impedance change, maintain constant signal transmission quality, automation of manufacturing, and overall FPCB It can be manufactured to a thickness of 200 μm or less, so it can be used for thin and thin products, and it is possible to manufacture fine signal lines and has excellent characteristics in EMC.

Hereinafter, a flexible printed circuit board for a high-capacity signal transmission medium according to an embodiment of the present invention will be described in detail with reference to the accompanying example drawings.

2 is a block diagram showing a general digital TV structure. Referring to FIG. 2, the digital TV converts a digital broadcast signal into a digital signal on the TV itself, that is, the TV main board 110 to convert low-voltage differential signaling (LVDS) through the LVDS transmission medium 120 to the LCD panel or PDP. The image is transmitted to the display device 130 such as a panel and displayed in the form of an image determined by the viewer.

3 is an exploded perspective view showing a flexible printed circuit board for a high-capacity signal transmission medium according to an embodiment of the present invention. 4 is a cross-sectional view of the flexible printed circuit board for the high-capacity signal transmission medium shown in FIG. 3. FIG. 5 is a view showing a photograph of a flexible printed circuit board for a high-capacity signal transmission medium shown in FIG. 3.

A flexible printed circuit board for a high-capacity signal transmission medium according to an embodiment of the present invention includes a copper foil high-capacity signal wire 310, a copper foil ground layer 320, and an insulating layer 330.

In the copper foil large-capacity signal wiring 310, a plurality of pairs of first pads 312 having a positive phase and a second pad 314 having a negative phase are alternately spaced apart at regular intervals and alternately arranged in pairs, and are separated from the TV main board 110. The large-capacity signal is received and transmitted to the display device 130. 3 and 4 show four pairs of first pad 312 and second pad 314, but the invention is not so limited. That is, 5 to 16 pairs of the first pad 312 and the second pad 314 may be applied.

The large signal includes an LVDS signal. As the industry develops, the necessity of transmitting a large amount of data at a high speed gradually increases, and the existing TTL-level communication is subject to many limitations, and the emergence of a new communication protocol is required. Therefore, the existing serial interface was used as a synchronous parallel interface, and the transmission width was extended to 8, 16, 32 bits and so on. However, each interface has advantages and disadvantages, and there are various problems such as complicated EMI countermeasures, increased wire rods, increased power consumption, and increased costs. As a solution to these physical bottlenecks, LVDS has been proposed and used as a standard in IEEE and ANSI / EIA.

As the demand for high-speed data generation and processing increases, the ability to transfer data from one point to another has become a measure of overall system performance. Therefore, LVDS is in the spotlight as a solution to solve the problem of high-speed data transmission. Devices such as software-defined radios (SDRs), high-performance data converters, high-resolution flat panel monitors, and digital televisions already have LVDS technology. LVDS is a high-speed digital interface, a common interface standard for high-speed data transmission. It features low power consumption and excellent noise immunity for high-speed data transfer rates. Since standardizing on ANSI / TIA / EIA-644, LVDS has been used in a variety of applications and industries. The ANSI / TIA / EIA-644 standard only defines the electrical characteristics of the LVDS interface driver outputs and receiver inputs. It does not define specific communication protocols, required process technology, media, or voltage supply. The ANSI / TIA / EIA-644-1995 standard also specifies specifications for the physical layer as an electronic interface, which defines only the electrical characteristics of the driver and receiver, and details of protocols, interconnections, or connectors. The characteristics are different for each application, so they are not defined separately. The LVDS standardization group only defines standards for electrical properties to drive LVDS as a versatile interface. Therefore, each application using LVDS should refer to its protocol and interconnect standards.

Because of its versatile and non-specific application, LVDS is being adopted in a variety of commercial and military applications. As the demand for bandwidth increases, high-performance technologies such as PCI Express and Hyper transport based on high-speed LVDS connections are emerging. Low power consumption, excellent noise immunity and the availability of a variety of commercial LVDS components make LVDS a reliable and long-term solution for high-speed data transmission in a variety of defense and aerospace applications.

At present, there are various application fields using LVDS. There are stackable hubs for data communications, as well as mobile wireless base station and ATM switch applications, computer FPDs and servers, peripherals such as printers and digital copiers, industrial high resolution displays and automotive FPD markets. In such applications, high-speed data moves within or between systems, and data movement within a system is called an intra system. LVDS solutions are mainly used in this area. Information movement between systems requires standard communication protocols such as IEEE1394, Fiber Channel, and Gigabit Ethernet. The hardware and software of these protocols are expensive, making them difficult to implement in intra systems. Therefore, inexpensive and easy LVDS links are mainly adopted in intra systems. As such, the LVDS solution is advantageous for data transfer on board and between boards, modules, shelves, racks, or boxes. The transmission medium can also be a copper wire or a trace of a PCB. In the future, LVDS will also implement protocols for intersystem communication.

The copper foil ground layer 320 is attached to the copper foil large-capacity signal wire 310 at a distance to ground the large-capacity signal transmitted to the display device 130 and returned.

The insulating layer 330 is bonded between the copper foil high-capacity signal wire 310 and the copper foil ground layer 320 so as to insulate between the copper foil high-capacity signal wire 310 and the copper foil ground layer 320. Keep it. The insulating layer 330 is preferably formed of polyimide having a dielectric constant of 2.7. Insulator material has a constant dielectric constant, the general polyimide has a dielectric constant of 4.2 ~ 4.7, it is difficult to thin the thickness, while the material used in the present invention has a dielectric constant of 2.7 to obtain a desired impedance value even at low thickness To help.

First pad 312 and second of copper foil high-capacity signal wire 310 such that first pad 312 and second pad 314 of copper foil high-capacity signal wire 310 are controlled to 80-110 Ω impedance. The width of the pad 314 is in the range of 80 to 110 μm, and the thicknesses of the first pad 312 and the second pad 314 and the copper foil ground layer 320 of the copper foil high-capacity signal wire 310 are respectively. It is preferably in the range of 30 to 40 μm, and the thickness of the insulating layer 330 is in the range of 20 to 30 μm.

According to the present invention, a first adhesive having a thickness of 5 to 15 μm that adheres the first pad 312 and the second pad 314 and the insulating layer 330 of the copper foil high-capacity signal wiring 310 using a first adhesive agent. Adhesive layer 340; A second adhesive layer 350 having a thickness of 5 to 15 μm that bonds the copper foil ground layer 320 to the insulating layer 330 using a second adhesive; And a copper foil power wire 360 having a thickness of 30 to 40 μm attached at a distance from one of the first pad 312 and the second pad 314 of the copper foil large-capacity signal wire 310.

According to an embodiment of the present invention, a third adhesive layer 370 having a thickness of 20 to 30 μm is laminated on the first adhesive layer so that the copper foil high-capacity signal wiring 310 and the copper foil power wiring 360 are covered: the third adhesive layer 170. A first coverlay layer 180 having a thickness of about 7 μm to about 17 μm attached to the copper foil to protect the high-capacity signal line 310; A fourth adhesive layer 390 having a thickness of 20 to 30 μm applied to the surface of the copper foil ground layer 320; And a second coverlay layer 400 having a thickness of 7 to 17 μm attached to the fourth adhesive layer 390 to protect the copper foil ground layer 320.

It is preferable that the total thickness of the flexible printed circuit board for a large-capacity signal transmission medium having such a configuration has a range of 174 to 274 µm.

Although the present invention has been described as a specific preferred embodiment, the present invention is not limited to the above-described embodiments, and the present invention is not limited to the above-described embodiments without departing from the gist of the present invention as claimed in the claims. Anyone with a variety of variations will be possible.

The flexible printed circuit board for high capacity signal transmission media according to the present invention can be used for all high capacity signal transmission media including LVDS.

1 is a diagram illustrating a flexible flat cable for a conventional LVDS signal transmission medium.

2 is a block diagram showing a general digital TV structure.

3 is an exploded perspective view showing a flexible printed circuit board for a high-capacity signal transmission medium according to an embodiment of the present invention.

4 is a cross-sectional view of the flexible printed circuit board for the high-capacity signal transmission medium shown in FIG. 3.

FIG. 5 is a view showing a photograph of a flexible printed circuit board for a high-capacity signal transmission medium shown in FIG. 3.

<Explanation of symbols for the main parts of the drawings>

110: TV main board

120: signal transmission medium

130: display device

310: copper foil large signal wiring

320: copper foil ground layer

330: insulation layer

340: first adhesive layer

350: second adhesive layer

360: copper foil power wiring

370: third adhesive layer

380: first coverlay layer

390: fourth adhesive layer

400: second coverlay layer

Claims (4)

A copper foil large-capacity signal line in which a first pad having a positive phase and a second pad having a negative phase are spaced at regular intervals and alternately arranged in a plurality of pairs, and receiving a large-capacity signal from a TV main board and transmitting the large-capacity signal to a display device; A copper foil grounding layer attached to the copper foil large-capacity signal line at a distance to ground the large-capacity signal transmitted to the display device and returned; And An insulating layer adhered between the copper foil high-capacity signal wire and the copper foil ground layer to insulate the copper foil high-capacity signal wire and the copper foil ground layer, The widths of the first pad and the second pad of the copper foil high-capacity signal wiring have a range of 80 to 110 μm so that the first pad and the second pad of the copper foil high-capacity signal wiring are controlled to 80-110 Ω impedance, respectively. A flexible printed circuit for a high-capacity signal transmission medium having a thickness of the first pad and the second pad of the high-capacity signal wiring and the copper foil ground layer each having a range of 30 to 40 μm, and the thickness of the insulating layer having a range of 20 to 30 μm. Board. 2. The flexible printed circuit board of claim 1, wherein the high-capacity signal comprises an LVDS signal and the insulating layer is formed of polyimide having a dielectric constant of 2.7. According to claim 1, A first adhesive layer 340 having a thickness of 5 ~ 15 ㎛ to bond the first and second pads and the insulating layer of the copper foil high-capacity signal wiring using a first adhesive;  A second adhesive layer having a thickness of 5 to 15 μm that bonds the copper foil ground layer and the insulating layer with a second adhesive; And And 30 to 40 μm thick copper foil power wiring attached at a distance from one of the first pad and the second pad of the copper foil large-capacity signal wiring. The third adhesive layer of claim 3, wherein the third adhesive layer having a thickness of 20 to 30 μm is laminated on the first adhesive layer to cover the copper foil large-capacity signal wiring and the copper foil power wiring. A first coverlay layer having a thickness of 7 to 17 μm attached to the third adhesive layer to protect the copper foil large signal wiring; A fourth adhesive layer having a thickness of 20 to 30 μm applied to the surface of the copper foil ground layer; And A second coverlay layer having a thickness of 7 to 17 μm attached to the fourth adhesive layer to protect the copper foil ground layer; Flexible printed circuit board for high-capacity signal transmission media with a total thickness in the range of 174 to 274 μm.

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