CN110798967A - Flexible board structure, TO optical module and optical transmission device - Google Patents

Abstract

The invention discloses a flexible board structure, a TO optical module and an optical transmission device, wherein the flexible board structure includes a first area connected with a TO optical device and a second area connected with the first area, and the first area is formed with a TO The high-speed signal hole corresponding to the high-speed signal pin of the optical device, the flexible board structure includes a first cover film, a first metal layer, a base material and a second metal layer stacked in sequence from top to bottom, and the first metal layer is configured to provide The ground plane, the second metal layer is formed with a high-speed signal link, the first cover film is configured to be assembled toward the TO optical device, the first cover film is formed with a through hole adjacent to the high-speed signal hole in the first area, and the first metal layer is located on the ground plane. The through hole is exposed, the through hole is filled with a conductive material connected to the first metal layer, and the conductive material extends upward beyond the first cover film. The present invention can be suitable for high-speed signal transmission, and has simple manufacturing process and lower manufacturing cost.

Description

Flexible board structure, TO optical module and optical transmission device

technical field

The invention relates to the technical field of optical communication, in particular to a flexible board structure, a TO optical module and an optical transmission device.

Background technique

At present, driven by the demand of the fifth-generation communication network 5G wireless fronthaul and ultra-large broadband data centers, the speed requirements of its core components, the optical transceiver modules, are getting higher and higher. In terms of 5G wireless fronthaul, 25Gbps optical modules have become the mainstream, and the market demand is huge. In addition, high-speed optical modules are more widely used in data centers.

The commonly used packaging forms of optical modules include TO packaging and Box packaging. TO package (as shown in Figure 1) is simple in process and low in cost. It is the mainstream packaging form of optical modules in the past, but it cannot be applied in high-speed and ultra-high-speed optical modules. The Box package uses a ceramic socket to assemble optical chips, electrical chips and optical devices, etc., to achieve high-speed packaging, but its cost is extremely high, 5-10 times the price of TO packaging, and the packaging process requirements are extremely high.

The TO package has a simple manufacturing process and extremely low cost, but it can only be maturely applied to low-speed optical modules with a rate of 10G and below. The reason is that the special structure of the TO packaged optical module causes the internal laser chip and the external circuit Driver driver The high-speed link is too long and the path is complex. The entire link trace is located in the PCB hard board, the FPC soft board and the TO pins (as shown in Figure 1), especially the interface between the TO optical device and the FPC soft board. Ultra-high-speed signals will cause serious signal reflection and loss here, which often causes the performance of optical modules to fail to meet the index requirements. Figure 2 is a schematic diagram of a TO optical device. The pins of the TO optical device need to be inserted into the pre-designed pin holes of the FPC soft board. There is a circle of pads around the pin holes. Solder is used to connect the pins and the pads through the soldering process. Finally, the extra length of the pins is cut off to complete the connection between the FPC flexible board and the TO optical device.

The interface between the FPC flexible board and the TO optical device is the most important reason for the deterioration of ultra-high-speed signal transmission. The design of the line can meet the standard impedance requirements, but the conversion of the transmission mode at the interface often brings about the resonant problem with devastating effects, which is the key technical bottleneck that TO packaging has been unable to apply to high-speed and ultra-high speed. The probability of appearing at low speed is very small.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a flexible board structure, which can be suitable for high-speed signal transmission when used in a TO optical module.

Another object of the present invention is to provide a TO optical module, which can be suitable for high-speed signal transmission.

Another object of the present invention is to provide an optical transmission device, which can be suitable for high-rate signal transmission.

In order to achieve the above object, the present invention provides a flexible board structure for connecting with a TO optical device, the flexible board structure includes a first area connected with the TO optical device and a second area connected with the first area , a high-speed signal hole corresponding to the high-speed signal pin of the TO optical device is formed on the first area, and the flexible board structure includes a first cover film, a first metal layer, a base material and A second metal layer configured to provide a ground plane, the second metal layer formed with a high-speed signal link, the first cap film configured to mount toward the TO optical device, the first The cover film is formed with a through hole adjacent to the high-speed signal hole in the first region, the first metal layer is exposed at the through hole, and the through hole is filled with a connection to the first metal layer. a conductive material that extends upward beyond the first cover film.

Preferably, the through hole is a circular hole with a diameter between 0.6 mm and 0.9 mm.

Preferably, the first cover film is provided with one or more through holes adjacent to each of the high-speed signal holes.

Preferably, the conductive material is thermally cured in the through hole.

Preferably, the conductive material is conductive glue or metal solder.

Preferably, the flexible board structure further includes a second cover film, and the second cover film covers the second metal layer.

In order to achieve the above-mentioned other object, the present invention provides a TO optical module, including a TO optical device and the above-mentioned flexible board structure.

In order to achieve the above-mentioned further object, the present invention provides an optical transmission device, comprising the above-mentioned TO optical module and a circuit board, and the end of the second area of the flexible board structure away from the first area is connected to the the circuit board.

Compared with the prior art, the flexible board structure of the present invention is formed with a through hole exposing the first metal layer at a position adjacent to the high-speed signal hole on the first cover film, and the through hole is filled with a connection with the first metal layer. The conductive material extends upwards beyond the first cover film; during use, the impedance of the interface between the TO optical device and the flexible board structure can be adjusted to be near the desired value to improve the impedance matching effect, and at the same time, it can reduce high-frequency noise and reduce signal. loss, the resonant frequency can be raised to a higher frequency band, so that the present invention can move the resonant frequency to a frequency band far away from signal transmission, so that the present invention can be applied to high-speed signal transmission.

Description of drawings

FIG. 1 is a schematic structural diagram of an optical transmission device.

FIG. 2 is a schematic three-dimensional structure diagram of a TO optical device.

FIG. 3 is a schematic three-dimensional structural diagram of a flexible board structure according to an embodiment of the present invention.

FIG. 4 is a schematic diagram of an exploded structure of a flexible board structure according to an embodiment of the present invention, wherein the conductive material is hidden.

FIG. 5 is another schematic diagram of the exploded structure of the flexible board structure according to the embodiment of the present invention, in which the conductive material is hidden.

6 is a schematic cross-sectional view of a partial structure of a flexible board structure according to an embodiment of the present invention.

Detailed ways

In order to describe the technical content and structural features of the present invention in detail, further description will be given below with reference to the embodiments and the accompanying drawings.

Please refer to FIGS. 1 to 6 , the present invention discloses a flexible board structure 1 for connecting with a TO optical device 7 , the flexible board structure 1 includes a first region Z1 connected with the TO optical device 7 and a first region Z1 connected with the TO optical device 7 The second area Z2 connected by Z1, the high-speed signal hole 10 corresponding to the high-speed signal pin 71 of the TO optical device 7 is formed in the first area Z1, and the flexible board structure 1 includes the first cover film 20 stacked in sequence from top to bottom , the first metal layer 30, the base material 40 and the second metal layer 50, the first cover film 20 can play the role of protecting the first metal layer 30 and improving the reliability of the entire package, and the first metal layer 30 is configured to provide grounding Plane, the second metal layer 50 is formed with a high-speed signal link, the first cover film 20 is configured to be assembled toward the TO optical device 7, and the first cover film 20 is formed with a through hole 21 adjacent to the high-speed signal hole 10 in the first area Z1 , the first metal layer 30 is exposed at the through hole 21 , the through hole 21 is filled with a conductive material 22 connected to the first metal layer 30 , and the conductive material 22 extends upward beyond the first cover film 20 . Specifically, the high-speed signal link includes pads 51 , high-speed signal lines 52 and the like formed on the periphery of the high-speed signal hole 10 . In addition, in a specific example, pads 53 and 54 located on the periphery of the DC signal hole 11 and the ground signal hole 12 are further formed on the second metal layer 50 .

Because the flexible board structure 1 of the present invention can adjust the impedance of the interface position between the TO optical device 7 and the flexible board structure 1 to be near the desired value during use, the impedance matching effect can be improved, and high-frequency noise and signal loss can be reduced at the same time. The resonant frequency is moved to a frequency band far away from the signal transmission frequency band, so that the present invention can be applied to the transmission of high-speed signals, and at the same time, it has a simple manufacturing process and a lower manufacturing cost.

Referring to FIGS. 3 to 5 , in some embodiments, the through hole 21 is a circular hole with a diameter between 0.6 mm and 0.9 mm. Of course, it is not limited to this, and in other embodiments, the through hole 21 may also be a circular hole with other diameters or a non-circular hole.

Referring to FIGS. 3 to 5 , in some embodiments, the first cover film 20 is provided with one or more through holes 21 adjacent to each of the high-speed signal holes 10 . That is, for each high-speed signal hole 10, one or more than one through hole 21 may be provided near it and filled with conductive material 22 upward beyond the first cover film 20 at the through hole 21 to improve high speed the transmission capacity of the signal.

Referring to FIG. 3 and FIG. 6 , in some embodiments, the conductive material 22 is thermally cured in the through hole 21 , and the missile material is preferably conductive glue or metal solder. Of course, in other embodiments, the conductive material 22 is not limited to the heat-curable conductive material 22 .

Please refer to FIG. 2 and FIG. 3 , in a specific example, the first region Z1 is further formed with a DC signal hole 11 and a ground signal hole 12 corresponding to the DC signal pin 72 and the ground signal pin 73 of the TO optical device 7 , The DC signal hole 11 and the ground signal hole 12 are arranged along the longitudinal direction of the flexible board structure 1. The ground signal hole 12 is closer to the second area Z2 than the DC signal hole 11. The first area Z1 is formed with two high-speed signal holes 10. The high-speed signal holes 10 are located between the DC signal holes 11 and the ground signal holes 12 in the longitudinal direction of the FPC structure 1, and are respectively located in the DC signal holes 11 in the lateral direction (the direction perpendicular to the longitudinal direction) of the FPC structure 1 On both sides of the ground signal hole 12 , through holes 21 are respectively formed in the first region Z1 on one side of the two high-speed signal holes 10 close to the second region Z2 . Of course, this is only a specific embodiment of the present invention. In the case where the flexible board structure 1 has the same arrangement of high-speed signal holes 10 , DC signal holes 11 and ground signal holes 12 , the through holes 21 can also be arranged on the side of the through holes 21 . The outer side or the side away from the second zone Z2. Moreover, it should be noted that the flexible board structure 1 of the present invention is not limited to be set for the TO optical device 7 with a specific number of pins and a specific pin arrangement, as long as the TO optical device 7 has high-speed signal pins 71, the corresponding , the flexible board structure 1 is formed with a high-speed signal hole 10 to be matched with it, and the present invention can be applied.

Referring to FIGS. 4 to 6 , in some embodiments, the flexible board structure 1 further includes a second cover film 60 , and the second cover film 60 covers the second metal layer 50 .

Please refer to FIG. 1 to FIG. 3 , the present invention also discloses a TO optical module, which includes a TO optical device 7 and the flexible board structure 1 as described in the above-mentioned embodiment.

Please refer to FIG. 1 , the present invention also discloses an optical transmission device, comprising the TO optical module and the circuit board 8 as described above, and the end of the second area Z2 of the flexible board structure 1 away from the first area Z1 is connected to the circuit board 8.

To sum up, since the flexible board structure 1 of the present invention is formed with a through hole 21 exposing the first metal layer 30 at a position on the first cover film 20 adjacent to the high-speed signal hole 10 , and the through hole 21 is filled with the first metal layer 30 . A metal layer 30 is connected to the conductive material 22 of the first cover film 20 and extends upwards. When in use, the impedance of the interface position between the TO optical device 7 and the flexible board structure 1 can be adjusted to be close to the desired value, so as to improve the impedance matching effect. By reducing high-frequency noise and signal loss, the resonant frequency can be moved to a frequency band far away from signal transmission, so that the present invention can be suitable for high-speed signal transmission, and has simple manufacturing process and extremely low manufacturing cost. The present invention utilizes the TO package structure to realize high-quality signal transmission of 25 Gbps and higher rates, without requiring a high-cost BOX package.

The above disclosures are only preferred examples of the present invention, and cannot be used to limit the scope of rights of the present invention. Therefore, the equivalent changes made according to the claims of the present invention all belong to the scope covered by the present invention.

Claims (8)

1. A flexible board structure for connecting TO an optical device, comprising a first region connected TO the TO optical device and a second region connected TO the first region, the first region is formed with high-speed signal holes corresponding TO the high-speed signal pins of the TO optical device, the flexible board structure comprises a first covering film, a first metal layer, a base material and a second metal layer which are sequentially stacked from top to bottom, the first metal layer configured to provide a ground plane, the second metal layer formed with a high speed signal link, the first cover film is configured TO be fitted toward the TO optical device, the first cover film is formed with a through hole adjacent TO the high-speed signal hole in the first region, the first metal layer is exposed at the through hole, the through hole is filled with a conductive material connected with the first metal layer, and the conductive material extends upwards beyond the first cover film.

2. The flexible board structure according to claim 1, wherein the through-holes are circular holes having a diameter of 0.6mm to 0.9 mm.

3. The flexible printed circuit board structure of claim 1, wherein said first cover film is provided with one or more through holes adjacent to each of said high speed signal holes.

4. The flexible board structure according to claim 1, wherein the conductive material is thermally cured in the through-hole.

5. The flexible board structure of claim 4, wherein the conductive material is conductive paste or metal solder.

6. The flexible board structure according to claim 1, further comprising a second cover film covering the second metal layer.

7. A TO optical module comprising a TO optical device and the flexible board structure according TO any one of claims 1 TO 6.

8. An optical transmission device comprising the TO optical module according TO claim 7 and a circuit board, wherein an end of the second region of the flexible board structure, which is away from the first region, is connected TO the circuit board.

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