A soft board structure, a TO optical module and an optical transmission device

Abstract

The application discloses a soft board structure, a TO optical module and an optical transmission device. The soft board structure comprises a first metal layer, a substrate and a second metal layer which are stacked from bottom to top. The first metal layer is configured to provide a ground plane. The second metal layer is formed with a high-speed signal link. The soft board structure is formed with a first high-speed signal through hole and a second high-speed signal through hole. The soft board structure is formed with a first opening and a second opening near the first high-speed signal through hole and the second high-speed signal through hole. The sidewalls of the first opening and the second opening are provided with metal welding materials connected with the first metal layer. When the soft board structure is assembled with a TO optical device, the first opening and the second opening are filled with conductive materials connected with the pipe seat and the metal welding materials. The application can be applied to the transmission of high-speed signals, and has a simple manufacturing process and low manufacturing cost.

Description

Technical Field

[0001] The present invention relates to the field of optical communication technology, and in particular to a flexible board structure, a TO optical module and an optical transmission device. Background Art

[0002] Driven by the demand for 5G wireless fronthaul and ultra-large broadband data centers, the speed requirements for optical transceiver modules, the core components of fifth-generation communication networks, are increasing. In 5G wireless fronthaul, 25Gbps optical modules are becoming mainstream, generating enormous market demand. Furthermore, high-speed optical modules are becoming increasingly common in data centers.

[0003] Common packaging forms for optical modules include TO packaging and Box packaging. Figure 1 ) was the mainstream packaging format for optical modules in the past due to its simple process and low cost, but it was not suitable for high-speed and ultra-high-speed optical modules. The Box package uses a ceramic header to assemble optical chips, electronic chips, and optical components, enabling high-speed packaging. However, it is extremely expensive, 5-10 times the price of a TO package, and requires extremely high packaging technology.

[0004] TO packaging 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 package optical module causes the high-speed link between the internal laser chip and the external circuit driver to be too long and the path is too complicated. The entire link routing is located in the PCB hard board, FPC soft board and TO pins (such as Figure 1 ), especially the interface between TO optical devices and FPC soft boards, where high-speed and ultra-high-speed signals will experience severe signal reflection and loss, often resulting in the optical module performance failing to meet index requirements. Figure 2 This 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. There is a circle of solder pads around the pin holes. Solder is used to connect the pins to the pads through a welding process. Finally, the excess pin length is cut off to complete the connection between the FPC and the TO optical device.

[0005] The interface between the FPC and TO optical devices is the most significant cause of deterioration in ultra-high-speed signal transmission. This is primarily due to the completely different transmission modes of high-speed lines on TO optical devices and FPC. Even if the design of high-speed or ultra-high-speed lines meets standard impedance requirements, the conversion of transmission modes at the interface often leads to devastating resonance problems. This is the key technical bottleneck that has prevented TO packaging from being applied to high-speed and ultra-high-speed applications. This problem is less likely to occur in low-speed optical module applications. Summary of the Invention

[0006] The object of the present invention is to provide a flexible board structure that can be suitable for high-speed signal transmission when used in a TO optical module.

[0007] Another object of the present invention is to provide a TO optical module suitable for transmission of high-speed signals.

[0008] Another object of the present invention is to provide an optical transmission device that is suitable for transmitting high-speed signals.

[0009] To achieve the above-mentioned objectives, the present invention provides a flexible board structure for connecting to a TO optical device, wherein the flexible board structure includes a first metal layer, a substrate, and a second metal layer stacked in sequence from bottom to top, wherein the first metal layer is configured to provide a ground plane, and the second metal layer forms a high-speed signal link. A first high-speed signal through-hole and a second high-speed signal through-hole are formed on the flexible board structure, and a first opening and a second opening are respectively formed on the flexible board structure at positions close to the first high-speed signal through-hole and the second high-speed signal through-hole, and the sidewalls of the first opening and the second opening are provided with metal welding materials connected to the first metal layer.

[0010] Preferably, the first opening and the second opening are notches extending outward through edges of the flexible board structure.

[0011] Preferably, the first through-hole and the second through-hole are respectively formed at positions closest to the first high-speed signal through-hole and the second high-speed signal through-hole on the edge of the flexible board structure.

[0012] Preferably, the first opening and the second opening are circular, elliptical, triangular or rectangular.

[0013] Preferably, the metal welding material extends along the side walls of the first opening and the second opening.

[0014] Preferably, the flexible board structure further includes a first covering film provided on the lower side of the first metal layer, and the first metal layer is exposed in an area corresponding to the TO optical device.

[0015] To achieve the above-mentioned another object, the present invention provides a TO optical module, including a TO optical device and a flexible board structure, the TO optical device including a tube holder and a first high-speed signal pin and a second high-speed signal pin provided on the tube holder, the flexible board structure as described above, the flexible board structure being installed on the TO optical device, the first high-speed signal through-hole and the second high-speed signal through-hole correspondingly housing the first high-speed signal pin and the second high-speed signal pin, and the first through-hole and the second through-hole being filled with a conductive material connecting the tube holder and the metal welding material.

[0016] Preferably, the conductive material is metal solder or conductive adhesive.

[0017] To achieve another of the above objectives, the present invention provides an optical transmission device, comprising the TO optical module and a circuit board as described above, wherein one end of the flexible board structure away from the TO optical device is connected to the circuit board.

[0018] Compared with the prior art, the present invention forms a first opening and a second opening on the flexible board structure near the first high-speed signal through-hole and the second high-speed signal through-hole, respectively, and provides metal welding materials connected to the first metal layer on the side walls of the first opening and the second opening, respectively. After the flexible board structure and the TO optical device are assembled, the metal welding materials of the flexible board structure and the stem metal of the TO optical device can be connected by using the conductive material filled in the first opening and the second opening, thereby improving the grounding performance of the TO optical module to improve the backflow of high-speed signals, and adjusting the impedance at the interface between the TO optical device and the flexible board structure to near the desired value, thereby improving the impedance matching effect, reducing high-frequency noise, reducing signal loss, and moving the resonant frequency to a frequency band far away from signal transmission, so that the present invention can be suitable for the transmission of high-speed signals, while having a simple manufacturing process and low manufacturing cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0019] Figure 1 It is a structural schematic diagram of an optical transmission device.

[0020] Figure 2 It is a schematic diagram of the three-dimensional structure of a TO optical device.

[0021] Figure 3 It is a schematic diagram of the three-dimensional structure of the flexible board structure according to an embodiment of the present invention.

[0022] Figure 4 It is a schematic diagram of the exploded structure of the flexible circuit board structure according to an embodiment of the present invention.

[0023] Figure 5 2 is another exploded structural diagram of the flexible circuit board structure according to an embodiment of the present invention.

[0024] Figure 6 It is a schematic diagram of the partial structure of the flexible board structure assembled on the TO optical device according to an embodiment of the present invention. DETAILED DESCRIPTION

[0025] In order to explain the technical content and structural features of the present invention in detail, the following is a further description in conjunction with the embodiments and the accompanying drawings.

[0026] See also Figures 1 to 6The present invention discloses a flexible circuit board structure 1 for connecting to a TO optical device 7. The flexible circuit board structure 1 includes a first metal layer 20, a substrate 30, and a second metal layer 40 stacked sequentially from bottom to top. The first metal layer 20 is configured to provide a ground plane, and the second metal layer 40 forms a high-speed signal link. The flexible circuit board structure 1 is formed with a first high-speed signal via 11 and a second high-speed signal via 12. The flexible circuit board structure 1 has a first opening 13 and a second opening 14 formed near the first and second high-speed signal vias 11 and 12, respectively. The sidewalls of the first and second openings 13 and 14 are provided with metal solder 15 connected to the first metal layer 20. Specifically, the high-speed signal link includes pads 41 and high-speed signal lines 42 formed on the periphery of the high-speed signal vias 11 and 12. In addition, in this specific example, the second metal layer 40 is further formed with solder pads 43 and 44 located around the DC signal via 16 and the ground signal via 17. The DC signal via 16 and the ground signal via 17 are used to mate with the DC signal pin 73 and the ground signal pin 74 of the TO optical device 7. It should be noted that the flexible circuit board structure 1 of the present invention can be configured to correspond to TO optical devices 7 having different numbers and pin arrangements. In this specific example of the present invention, the number of the first opening 13 and the second opening 14 is one, but this is not limiting.

[0027] After the flexible board structure 1 of the present invention is assembled with the TO optical device 7, the metal welding material 15 of the flexible board structure 1 and the metal of the tube seat 70 of the TO optical device 7 can be connected by using the conductive material T filled in the first opening 13 and the second opening 14, thereby improving the grounding performance of the TO optical module to improve the backflow of high-speed signals, and adjusting the impedance at the interface position between the TO optical device 7 and the flexible board structure 1 to near the expected value, thereby improving the impedance matching effect, reducing high-frequency noise, reducing signal loss, and moving the resonant frequency to a frequency band far away from signal transmission, so that the present invention can be applied to the transmission of high-speed signals, while having a simple manufacturing process and low manufacturing cost.

[0028] See also Figure 3 In some embodiments, the first opening 13 and the second opening 14 are notches extending outward through the edge of the flexible circuit board structure 1. This design facilitates filling the first and second openings 13, 14 with the conductive material T after the flexible circuit board structure 1 and the TO optical device 7 are assembled. Of course, in other embodiments, the first and second openings 13, 14 are not limited to notches. For example, the first and second openings 13, 14 can also be through-hole structures located adjacent to the first and second high-speed signal vias 11, 12, respectively.

[0029] As a preferred embodiment, first opening 13 and second opening 14 are formed at the edge of flexible circuit board structure 1, closest to first high-speed signal via 11 and second high-speed signal via 12, respectively. This facilitates adjusting the impedance at the interface between TO optical device 7 and flexible circuit board structure 1 and shifting the resonant frequency away from the signal transmission frequency band. "Closest" here refers to a relatively small area. In this embodiment, the number of first opening 13 and second opening 14 is typically one, but this is not a limitation.

[0030] See also Figure 3 and Figure 6 In this specific example, the flexible circuit board structure 1 is configured to correspond to the four-pin TO optical device 7. The first high-speed signal via 11 and the second high-speed signal via 12 are arranged on the same diameter in the area of ​​the flexible circuit board structure 1 corresponding to the TO optical device 7. The first opening 13 and the second opening 14 are located on the same diameter as the first high-speed signal via 11 and the second high-speed signal via 12. Of course, for the flexible circuit board structure 1 corresponding to the four-pin TO optical device 7, the arrangement of the first opening 13, the second opening 14, the first high-speed signal via 11, and the second high-speed signal via 12 is not limited to the above-described specific solution.

[0031] In some specific embodiments, the first opening 13 and the second opening 14 may be circular, elliptical, triangular, rectangular or other shapes, which are not limited herein.

[0032] See also Figure 3 In some embodiments, the metal welding material 15 extends along the sidewalls of the first opening 13 and the second opening 14 . Accordingly, the metal welding material 15 may be in a strip shape, a ring shape, or the like.

[0033] See also Figures 3 to 5 In some embodiments, the flexible circuit board structure 1 further includes a first cover film 50 disposed on the underside of the first metal layer 20, with the first metal layer 20 exposed in the area corresponding to the TO optical device 7. Of course, in other embodiments, the area of ​​the first metal layer 20 corresponding to the TO optical device 7 may also be covered by the first cover film 50; furthermore, the first cover film 50 is not necessarily required to be disposed on the underside of the first metal layer 20.

[0034] See also Figure 4 and Figure 5 In some embodiments, the flexible board structure 1 further includes a second covering film 60 disposed on the second metal layer 40. Of course, the second covering film 60 may not be disposed, and this is not limited here.

[0035] See also Figure 1 and Figure 6The present invention further discloses a TO optical module, including a TO optical device 7 and a flexible board structure 1. The TO optical device 7 includes a tube seat 70 and a first high-speed signal pin 71 and a second high-speed signal pin 72 provided on the tube seat 70. The flexible board structure 1 is as described in the above embodiment. The flexible board structure 1 is installed on the TO optical device 7. The first high-speed signal through-hole 11 and the second high-speed signal through-hole 12 are correspondingly provided with the first high-speed signal pin 71 and the second high-speed signal pin 72. The first through-hole 13 and the second through-hole 14 are filled with a conductive material T connecting the tube seat 70 and the metal welding material 15.

[0036] The metal welding material 15 of the flexible board structure 1 of the TO optical module of the present invention and the metal of the tube seat 70 of the TO optical device 7 are connected by the conductive material T filled in the first opening 13 and the second opening 14, thereby improving the grounding performance of the TO optical module to improve the backflow of high-speed signals, and adjusting the impedance at the interface position between the TO optical device 7 and the flexible board structure 1 to near the desired value, improving the impedance matching effect, and at the same time reducing high-frequency noise and signal loss, and moving the resonant frequency to a frequency band far away from signal transmission, making the present invention suitable for high-speed signal transmission. The present invention utilizes the TO package structure to achieve high-quality signal transmission at 25Gbps and higher rates without the need for high-cost BOX packaging.

[0037] Specifically, the conductive material T is metal solder or conductive adhesive, which is not limited here, as long as a stable connection between the metal solder 15 and the metal of the tube holder 70 can be achieved.

[0038] Please combine Figure 1 The present invention also discloses an optical transmission device, including the TO optical module and the circuit board 8 as described above, wherein one end of the flexible board structure 1 away from the TO optical device 7 is connected to the circuit board 8.

[0039] The above disclosure is only a preferred embodiment of the present invention and cannot be used to limit the scope of the present invention. Therefore, equivalent changes made according to the claims of the present invention are within the scope of the present invention.

Claims

1. A flexible board structure for connecting with a TO optical device, characterized in that: The flexible board structure includes a first metal layer, a substrate, and a second metal layer stacked in sequence from bottom to top, the first metal layer is configured to provide a ground plane, the second metal layer forms a high-speed signal link, a first high-speed signal through-hole and a second high-speed signal through-hole are formed on the flexible board structure, and a first through-hole and a second through-hole are respectively formed on the flexible board structure at positions close to the first high-speed signal through-hole and the second high-speed signal through-hole, the side walls of the first through-hole and the second through-hole are provided with metal welding materials connected to the first metal layer, and the metal welding materials are connected to the tube seat of the TO optical device through the conductive material filled in the first through-hole and the second through-hole.

2. The flexible board structure according to claim 1, characterized in that: The first opening and the second opening are notches that penetrate outwardly through the edge of the soft board structure.

3. The flexible board structure according to claim 2, characterized in that: The first through-hole and the second through-hole are respectively formed at positions on the edge of the flexible board structure that are closest to the first high-speed signal through-hole and the second high-speed signal through-hole.

4. The flexible board structure according to claim 2, wherein: The first opening and the second opening are circular, elliptical, triangular or rectangular.

5. The flexible board structure according to claim 1, wherein: The metal welding material extends along the side walls of the first opening and the second opening.

6. The flexible board structure according to claim 1, wherein: The invention also includes a first covering film provided on the lower side of the first metal layer, and the first metal layer is exposed in an area corresponding to the TO optical device.

7. A TO optical module, characterized in that: The TO optical device comprises a TO optical device and a flexible board structure, wherein the TO optical device comprises a tube holder and a first high-speed signal pin and a second high-speed signal pin provided on the tube holder. The flexible board structure is as described in any one of claims 1 to 6, wherein the flexible board structure is mounted on the TO optical device, wherein the first high-speed signal through-hole and the second high-speed signal through-hole are correspondingly provided with the first high-speed signal pin and the second high-speed signal pin, and the first through-hole and the second through-hole are filled with a conductive material connecting the tube holder and the metal welding material.

8. The TO optical module according to claim 7, wherein: The conductive material is metal solder or conductive glue.

9. An optical transmission device, characterized in that: It comprises the TO optical module and circuit board as claimed in claim 7, wherein one end of the flexible board structure away from the TO optical device is connected to the circuit board.

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