KR20060080901A - Device of signal delivery using optical flexible pcb - Google Patents

Abstract

The present invention relates to a signal transmission device using a flexible optical PCB including a polymer optical waveguide (Optical Waveguide) that is an optical signal transmission line. In the existing rigid coupling structure between the light source / photodetector and the optical waveguide using the lens, the manufacturing process can be simplified by using the optical waveguide to minimize the optical loss due to the alignment error, and the optical transmission / reception module It can be assembled by a manual alignment method can improve the economics and mass production. In addition, currently using a rigid substrate and a flexible PCB by the electrical connection to the mobile phone and laptop, etc. In the future, the flexible optical PCB of the present invention can be easily applied in various fields that require high-speed, large-capacity information transmission.

Optical waveguide, optical transmission module, optical reception module, flexible PCB

Description

Signal transmission device using flexible optical PCC {Device of signal delivery using optical flexible PCB}

1 is a signal transmission structure using a conventional rigid optical PCB.

2 is a detailed structural diagram of an optical signal transmission using a conventional rigid optical PCB.

3 is a cross-sectional view of an optical signal transmission apparatus using a flexible optical PCB according to the present invention.

Figure 4 is an enlarged cross-sectional view of the optical transmission module of the optical signal transmission apparatus using the flexible optical PCB of FIG.

5 is an enlarged cross-sectional view of an optical receiving module of the optical signal transmission apparatus using the flexible optical PCB of FIG. 3.

Figure 6 is an illustration of the optical coupling loss graph according to the optical connection distance (t) in the optical signal transmission apparatus using a flexible optical PCB according to the present invention.

7 is an overall configuration of the optical signal transmission device using a flexible optical PCB according to the present invention combined with a conventional rigid PCB.

<Brief description of the major symbols in the drawings>

1: Optical signal transmission device using flexible optical PCB

2: optical waveguide layer

3: copper wiring layer

4: dielectric layer

5: film cover layer

6: 45 ° reflecting surface of transmitter

7: 45 ° reflecting surface of receiver

8: electrical connector of transmitter

9: electrical connector on receiver

10: light source element

11: Transmit Chip

12: solder bump

16: Heat sink of transmitter

20: photodetector element

21: receiving chip

The present invention relates to an optical signal transmission device using an optical printed circuit board (PCB), and relates to an optical signal transmission device using a flexible optical PCB having a polymer optical waveguide layer embedded in a flexible PCB substrate.

Optical interconnect technologies are widely used for data transfer between systems over distances, data transfer between backplanes in systems, board-to-board connections within systems, and data transfer between chips on board.

In addition, various connection methods have been tried. Among them, for the application of board-to-board optical connection, which has a relatively short transmission distance, it is necessary to develop a structure applicable to the current PCB (Printed circuit board) technology. There is a need. Up to now, rigid optical PCBs in which optical fibers or polymer optical waveguides are stacked in PCBs have been mainly studied, but in the future, as the application fields of flexible PCBs such as many electronic products become wider, high-speed signal transmission through flexible PCBs becomes more and more. This is a required situation.

1 and 2 illustrate a typical optical connection module structure using an optical PCB of a type in which a conventional optical fiber or polymer optical waveguide is stacked in a PCB, and the optical module structure of FIG. A four-sided polymer optical waveguide 100 is embedded, and optical elements, IC circuits, and microlenses necessary for transmitting and receiving optical signals on a printed circuit board 102 are BGA ( Ball Grid Array) is an integrated structure on a substrate, and the optical module structure of FIG. 2 includes an optical transmission module in which a polymer optical waveguide 100 is stacked in a PCB, an optical via hole is drilled, and an optical device is integrated thereon. The optical reception module 200 is integrated, and the optical connection between the polymer optical waveguide 100 and the optical transmission module 200 has an optical waveguide for beam reflection of the optical signal in the optical via hole. It is a structure that is inserted.

However, the conventional optical module as shown in FIG. 1 has a structure that can be applied to a rigid PCB having a thickness of 1.2 mm to 3.2 mm, and in order to maintain an efficient optical connection efficiency because the divergence angle of the commonly used light source is VCSEL of 15 °. There was a problem that microlenses should be used on the module and the optical PCB.

In addition, in the optical module structure as shown in FIG. 2, the height of the reflecting surface of the carrier for reflecting the optical signal must match the core position of the optical waveguide stacked in the optical PCB. The position tolerance in the optical waveguide is maintained at 10% of the total thickness, so the position tolerance in the thickness direction of the optical waveguide core is 120 to 320 μm depending on the thickness of the board, and the passive alignment method of the reflective surface of the carrier and the core of the optical waveguide There is a problem that is very difficult to match, and when the substrate thickness is very thin, such as in the case of a flexible PCB, a few hundred μm or less, there is a problem that it is very difficult to precisely manufacture the carrier.

Disclosure of Invention An object of the present invention is to provide an optical signal transmission apparatus using a flexible optical PCB having a multilayer polymer optical waveguide layer capable of transmitting optical signals to various layers constituting a conventional flexible PCB.

The present invention relates to an optical signal transmission device using a flexible optical PCB, comprising a multilayer flexible material optical PCB having a multilayer optical waveguide layer capable of transmitting optical signals, and positioned on a top layer of the flexible optical PCB to transmit electrical signals to optical signals. And an optical transmission module for converting the optical signal to the multilayer optical waveguide layer and receiving the optical signal emitted from the optical transmission module and converting the optical signal into an electrical signal. The optical transmission module is a light source device using a vertical light emitting laser and a diode for converting an electrical signal into an optical signal, and is electrically connected to the light source device through flip chip bonding, and drives the optical signal to be emitted from the light source device. And a transmitting chip, wherein the optical receiving module is electrically connected to the photodetector using a vertical photosensitive diode that converts the received optical signal into an electrical signal, and is electrically connected to the photodetector through flip chip bonding and converted from the photodetector. And a receiving chip for amplifying the signal.

Figure 3 shows the overall structure (1) of the flexible optical PCB according to the present invention, referring to Figure 3, the layer configuration of the flexible optical PCB of the present invention is a polymer optical waveguide layer that is a transmission line of the optical signal ( 2) a copper wiring layer 3, a dielectric layer 4, a film cover layer 5, etc., which serve as transmission lines for electric signals.

The polymer optical waveguide layer 2 has a 45 ° reflecting surface 6 which transmits an optical signal at a right angle, and has a transmitting part and a receiving part. As shown in FIG. It consists of a clad layer. In addition, the polymer optical waveguide layer 2 may be manufactured by a conventional method such as a lithography process, hot embossing or rolling, and the 45 ° reflecting surfaces 6 and 7 are formed at precise positions by a grooving method using a diamond blade. For the purpose of improving the reflection efficiency, a metal such as gold or aluminum is coated on the reflective surface.

At the top layer of the flexible optical PCB, an optical transmission module 100 having a function of converting an electrical signal into an optical signal and an optical receiving module 200 having a function of converting the optical signal into an electrical signal are integrated. The optical signal emitted from the optical transmission module 100 is reflected by the 45 ° reflecting surface 6 formed in the polymer optical waveguide layer 2 through the dielectric layer 4 due to the difference in the refractive index of the polymer, and thus the polymer optical waveguide. While guided along (2), the light is reflected from the 45 ° reflecting surface 7 under the light receiving module 200 on the opposite side and is incident to the light receiving module 200. The electrical signal for driving the optical transmission module 200 is input by the electrical connector 8 at the end of the flexible optical PCB, and the electrical signal output from the optical reception module 200 is connected to the electrical connector 9 on the opposite side. Is output through The electrical connectors 8, 9 consist of solder fusing, pressure contacts, clamp-type connectors, and the like, which are commonly used in flexible PCBs.

In the optical transmission module 100 of FIG. 4, only a VCSEL 10 (vertical-cavity surface-emitting laser) for converting an electrical signal into an optical signal as an active element is integrated or driven so that an optical signal is emitted from the VCSEL 10. The transmitting chip 11 having a function of letting it work is integrated together. The solder chip 12 is bonded to the transmitting chip 11 for electrical connection with the flexible optical PCB.

Similarly, in the optical receiving module 200 of FIG. 5, only a photodiode 20 for converting a received optical signal into an electrical signal is used as an active element or a receiving chip 21 for amplifying an electrical signal. Are integrated. In addition, heat sinks 16 and 26 made of metal or the like are directly attached to the optical transmitting module 100 and the optical receiving module 200 for the purpose of removing heat generated from the transmitting or receiving optical modules 100 and 200. Or fixed to the opposite side of the flexible optical PCB.

FIG. 6 shows the distance between the optical output unit or optical input unit of the optical element in the optical transmission module 100 or the optical reception module 200 and the center of the core of the polymer optical waveguide 2 in the flexible optical PCB structure as shown in FIG. 3. Is a graph showing the optical connection loss according to the " optical coupling distance t " In an embodiment of the present invention, ray tracing, a technique commonly used in a multimode optical connection system, was used as an experimental method for measuring optical loss.

According to FIG. 6, it can be seen that the dependence of the optical connection loss on the optical connection distance t varies considerably depending on the width and height of the core in which the optical signal is guided in the polymer optical waveguide 2. The optical connection distance (t) is 50-400 μm, considering both the thickness of the flexible PCB 10 ~ 100 μm, the thickness of the clad and core of the polymer optical waveguide (2), and the height of the solder bumps (12). In this range, when the width and height of the optical waveguide 2 were both 50 μm, the loss was the smallest among the sizes of the tested cores, and the range was -0.5 to -2.3 dB, which was very small. Considering the waveguide loss (0.1 to 0.3 dB / cm) of the polymer optical waveguide and the receiving sensitivity of -16 dBm of the conventional receiving chip and the average power of the VCSEL 10 as 0 dBm, the optical signal can be transmitted through the flexible optical PCB. The distance (D) is up to 40 ~ 150cm can be applied to the optical connection between the board as well as the optical connection between the chip.

7 is an example of applying the basic structure of the flexible optical PCB of FIG. 7 shows a connection between the rigid PCB 300 and the board on which the layers are placed through the hybrid coupling of the flexible optical PCB 1 of the present invention. This is based on the flexibility that is a feature of the present invention and also a feature of the flexible optical PCB, and it is expected that the flexible optical PCB of the present invention will be utilized as a means for high-speed, large-capacity information transmission required in many various electronic products.

As described above, in the present invention, the structure of the flexible optical PCB can transmit a high-speed signal that is difficult to transmit with a conventional electrical flexible PCB, and because the optical coupling distance is short, there is no need to use a micro lens, and the optical transmission and reception module Can be assembled by a manual alignment method to improve the economics. In addition, the flexible optical PCB of the present invention can be easily applied to electronic products such as mobile phones and laptops.

As described above, in the present invention, a high speed signal can be transmitted by the structure of the flexible optical PCB, and the optical coupling distance is short, there is no need to use a micro lens, and the optical transmission and reception module is assembled by a manual alignment method. It is possible to reduce the manufacturing cost is possible to improve the economics there is an advantage. In addition, in the future, there is an advantage that the flexible optical PCB of the present invention can be easily applied to various electronic products such as mobile phones and notebooks requiring high speed and large data transfer and various applications.

Claims (5)

An optical signal transmission device using a flexible optical PCB, comprising a multilayer flexible material optical PCB having a multilayer optical waveguide layer capable of transmitting an optical signal, and positioned at the top layer of the flexible optical PCB to convert electrical signals and optical signals to each other. And optical signal transmission apparatus using a flexible optical PCB comprising an optical transmission and reception module for transmitting and receiving mutually with the optical waveguide layer. The optical waveguide layer of claim 1, wherein the optical waveguide layer has 45 ° inclined surfaces at both ends of the optical waveguide for reflecting 90 ° of vertically incident and emitted optical signals, and the 45 ° inclined surface is mirror coated to increase optical coupling efficiency. Optical signal transmission device using a flexible optical PCB characterized in that. The optical transmission module of claim 1, wherein the optical transmission module comprises a light source device using a vertical light emitting laser and a diode that converts an electrical signal into an optical signal, and is electrically connected to the light source device through flip chip bonding. Optical signal transmission apparatus using a flexible optical PCB, characterized in that it comprises a transmission chip for driving the optical signal to be emitted. The apparatus of claim 3, wherein the optical transmission module further includes a heat sink for dissipating heat on the light source element. The optical receiving module of claim 1, wherein the optical receiving module is electrically connected to the photodetector using a vertical photosensitive diode that converts the received optical signal into an electrical signal, and is electrically connected to the photodetector through flip chip bonding. Optical signal transmission device using a flexible optical PCB, characterized in that it comprises a receiving chip for amplifying the electrical signal.

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