CN110798967A

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

Info

Publication number: CN110798967A
Application number: CN201911218682.2A
Authority: CN
Inventors: 黄愚; 陈骁; 李海坚; 周斌; 黄旭
Original assignee: Guangwei Technology (guangzhou) Co Ltd
Current assignee: Guangwei Technology (guangzhou) Co Ltd; Liturex Guangzhou Co Ltd
Priority date: 2019-11-30
Filing date: 2019-11-30
Publication date: 2020-02-14

Abstract

The invention discloses a flexible board structure, a TO optical module and an optical transmission device, wherein the flexible board structure comprises a first area connected with a TO optical device and a second area connected with the first area, a high-speed signal hole corresponding TO a high-speed signal pin of the TO optical device is formed in the first area, 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 is configured TO provide a ground plane, the second metal layer is formed with a high-speed signal link, the first covering film is configured TO be assembled towards the TO optical device, a through hole adjacent TO the high-speed signal hole is formed in the first area of the first covering film, the first metal layer is exposed at the through hole, a conductive material connected with the first metal layer is filled in the through hole, and the conductive material upwards exceeds the first covering film. The invention can be suitable for the transmission of high-speed signals 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

Currently, the requirements for the speed of the optical transceiver module of the core component of the fifth generation communication network 5G are increasing under the push of the requirements of wireless forwarding and ultra-large broadband data centers. In the aspect of 5G wireless forward transmission, a 25Gbps optical module becomes the mainstream, and the market demand is huge. In addition, the use of high-speed optical modules in data centers is more extensive.

Common packaging forms of optical modules include TO packages, Box packages, and the like. The TO package (as shown in FIG. 1) has simple process and low cost, is the mainstream packaging form of the past optical module, but cannot be applied TO the high-speed and ultra-high-speed optical module. The Box package adopts a ceramic tube seat, and optical chips, electric chips, optical devices and the like are assembled in the ceramic tube seat, so that high-speed package can be realized, but the cost is extremely high and is 5-10 times of the price of TO package, and the packaging process requirement is extremely high.

The TO packaging manufacturing process is simple, the cost is extremely low, but the TO packaging manufacturing process can only be applied TO a low-speed optical module with the speed of 10G or below at present, because the special structure of the TO packaging optical module causes that a high-speed link between a laser chip inside the TO packaging optical module and an external circuit Driver is too long and has a complex path, the whole link routing is positioned in a PCB hard board, an FPC soft board and a TO pin (shown in figure 1), particularly at an interface between a TO optical device and the FPC soft board, high-speed and ultrahigh-speed signals can generate serious signal reflection and loss at the interface, and the performance of the optical module can not meet index requirements. Fig. 2 is a schematic diagram of a TO optical device, the pin of which needs TO be inserted into a pin hole pre-designed on an FPC flexible board. And a circle of bonding pads are arranged around the pin hole, the pin and the bonding pads are connected by using tin welding through a welding process, and finally the pin with the redundant length is cut off, so that the connection between the FPC soft board and the TO optical device is completed.

The interface between the FPC flexible board and the TO optical device is the most important reason causing the deterioration of ultra-high speed signal transmission, which is mainly shown in that the transmission modes of a high-speed line on the TO optical device and the FPC flexible board are completely different, even if the design of the high-speed line or the ultra-high speed line can meet the standard impedance requirement, the conversion of the transmission mode at the interface often brings the resonance problem with destructive influence, and the interface is a key technical bottleneck that the TO packaging can not be applied TO high speed and ultra-high speed all the time, and the probability of the problem occurring when the optical module is applied at low speed is very small.

Disclosure of Invention

The invention aims TO provide a flexible board structure which can be applied TO transmission of high-speed signals when used in a TO optical module.

Another object of the present invention is TO provide a TO optical module that can be applied TO transmission of high-rate signals.

It is still another object of the present invention to provide an optical transmission apparatus that can be applied to transmission of high-rate signals.

In order TO achieve the above object, the present invention provides a flexible printed circuit board structure for connecting TO an optical TO device, the flexible printed circuit board structure including a first region connected TO the optical TO device and a second region connected TO the first region, the first region having a high-speed signal hole corresponding TO a high-speed signal pin of the optical TO device formed thereon, the flexible printed circuit board structure including a first cover film, a first metal layer, a substrate and a second metal layer stacked in this order from top TO bottom, the first metal layer being configured TO provide a ground plane, the second metal layer having a high-speed signal link formed thereon, the first cover film being configured TO be assembled toward the optical TO device, the first cover film having a through hole formed therein adjacent TO the high-speed signal hole, the first metal layer being exposed at the through hole, the through hole being filled with a conductive material connected TO the first metal layer, the conductive material extends upwardly beyond the first cover film.

Preferably, the through hole is a circular hole with the diameter of 0.6mm to 0.9 mm.

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

Preferably, the conductive material is thermally cured within the via.

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

Preferably, the flexible printed circuit board structure further comprises a second cover film covering the second metal layer.

In order TO achieve another purpose, the invention provides a TO optical module which comprises a TO optical device and the soft board structure.

In order TO achieve the above-mentioned another object, the present invention provides an optical transmission device, which includes the TO optical module and a circuit board as described above, wherein an end of the second region of the flexible board structure, which is far away from the first region, is connected TO the circuit board.

Compared with the prior art, the soft board structure has the advantages that through holes for exposing the first metal layer are formed in the positions, adjacent to the high-speed signal holes, of the first cover film, the through holes are filled with conductive materials connected with the first metal layer, and the conductive materials upwards exceed the first cover film; when the optical fiber is used, the impedance of the interface position of the TO optical device and the flexible board structure can be adjusted TO be close TO an expected value, the impedance matching effect is improved, high-frequency noise can be reduced, signal loss is reduced, and the resonant frequency can be increased TO a higher frequency band, so that the resonant frequency can be moved TO a frequency band far away from signal transmission, and the optical fiber can be suitable for high-speed signal transmission.

Drawings

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

Fig. 2 is a schematic perspective view of a TO optical device.

Fig. 3 is a schematic perspective view of a flexible board structure according to an embodiment of the present invention.

Fig. 4 is an exploded view of a flexible printed circuit board according to an embodiment of the present invention, wherein the conductive material is hidden.

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

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

Detailed Description

In order to explain technical contents and structural features of the present invention in detail, the following description is made with reference to the embodiments and the accompanying drawings.

Referring TO fig. 1 TO 6, the present invention discloses a flexible board structure 1 for connecting TO a TO optical device 7, the flexible board structure 1 includes a first region Z1 connected TO the TO optical device 7 and a second region Z2 connected TO the first region Z1, a high-speed signal hole 10 corresponding TO a high-speed signal pin 71 of the TO optical device 7 is formed on the first region Z1, the flexible board structure 1 includes a first cover film 20, a first metal layer 30, a substrate 40 and a second metal layer 50 stacked in sequence from top TO bottom, the first cover film 20 can protect the first metal layer 30 and improve the reliability of the whole package, the first metal layer 30 is configured TO provide a ground 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, the first cover film 20 is formed with a through hole 21 adjacent TO the high-speed signal hole 10 in a first region Z1, the first metal layer 30 is exposed at the through hole 21, the conductive material 22 connected to the first metal layer 30 is filled in the through hole 21, and the conductive material 22 extends upward beyond the first cover film 20. Specifically, the high-speed signal link includes a pad 51, a high-speed signal line 52, and the like formed in the periphery of the high-speed signal hole 10. In addition, in a specific example,

pads

53 and 54 located at the periphery of the dc signal hole 11 and the ground signal hole 12 are also formed on the second metal layer 50.

When the flexible board structure 1 is used, the impedance of the interface position of the TO optical device 7 and the flexible board structure 1 can be adjusted TO be close TO an expected value, so that the impedance matching effect is improved, high-frequency noise can be reduced, signal loss is reduced, the resonant frequency can be moved TO a frequency band far away from signal transmission, the flexible board structure is suitable for transmission of high-speed signals, and meanwhile, the flexible board structure has a simple manufacturing process and lower manufacturing cost.

Referring to fig. 3 to 5, in some embodiments, the through hole 21 is a circular hole with a diameter of 0.6mm to 0.9 mm. Of course, the through hole 21 may be a circular hole with other diameter or a non-circular hole in other embodiments.

Referring to fig. 3 to 5, in some embodiments, the first cover film 20 is provided with one or more through holes 21 at positions adjacent to each high-speed signal hole 10. That is, for each high-speed signal hole 10, one or more than one through hole 21 may be provided at a position close thereto and the through hole 21 is filled with the conductive material 22 upwardly beyond the first coverlay 20 to improve the transmission capability of the high-speed signal.

Referring to fig. 3 and 6, in some embodiments, the conductive material 22 is thermally cured within the through-holes 21, and the missile material is preferably a conductive paste or metallic solder. Of course, in other embodiments, the conductive material 22 is not limited to the thermosetting type conductive material 22.

Referring TO fig. 2 and 3, in a specific example, the first region Z1 further forms 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 disposed along the longitudinal direction of the flexible board structure 1, the ground signal hole 12 is closer TO the second region Z2 than the dc signal hole 11, the first region Z1 forms two high-speed signal holes 10, the two high-speed signal holes 10 are located between the dc signal hole 11 and the ground signal hole 12 in the longitudinal direction of the flexible board structure 1, the two high-speed signal holes 10 are located on two sides of the dc signal hole 11 and the ground signal hole 12 in the transverse direction (the direction perpendicular TO the longitudinal direction) of the flexible board structure 1, and the first region Z1 forms a through hole 21 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, and in the case where the flexible board structure 1 has the high-speed signal hole 10, the direct-current signal hole 11, and the ground signal hole 12 which are arranged identically, the through hole 21 may be provided outside the through hole 21 or on the side away from the second region Z2. Further, it should be noted that the flexible board structure 1 of the present invention is not limited TO the arrangement of the TO optical devices 7 with a specific number of pins and a specific pin arrangement, and the present invention can be applied TO the flexible board structure 1 as long as the TO optical devices 7 have the high-speed signal pins 71, and accordingly, the high-speed signal holes 10 matched with the TO optical devices are formed on the flexible board structure 1.

Referring to fig. 4 to fig. 6, in some embodiments, the flexible printed circuit board 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 further discloses a TO optical module, which includes a TO optical device 7 and the flexible board structure 1 according TO the above embodiment.

Referring TO fig. 1, the present invention further discloses an optical transmission device, which includes the TO optical module and the circuit board 8, wherein an end of the second area Z2 of the flexible printed circuit board structure 1, which is far away from the first area Z1, is connected TO the circuit board 8.

In summary, since the through hole 21 exposing the first metal layer 30 is formed in the first cover film 20 of the flexible printed circuit board structure 1 adjacent TO the high-speed signal hole 10, and the conductive material 22 connected TO the first metal layer 30 and extending upward beyond the first cover film 20 is filled in the through hole 21, when in use, the impedance of the interface position between the TO optical device 7 and the flexible printed circuit board structure 1 can be adjusted TO be near the expected value, so as TO improve the impedance matching effect, reduce the high-frequency noise and the signal loss, and move the resonant frequency TO a frequency band far away from the signal transmission, so that the flexible printed circuit board structure 1 can be applied TO the transmission of high-speed signals, and has a simple manufacturing process and a very low manufacturing cost. The TO packaging structure can realize high-quality signal transmission at 25Gbps and higher speed without a high-cost BOX packaging form.

The above disclosure is only a preferred embodiment of the present invention, and should not be taken as limiting the scope of the invention, so that the appended claims are intended to cover all such modifications and changes as fall within the true spirit of the invention.

Claims

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.