Light receiving assembly

Abstract

The utility model provides a light receiving assembly, including rigid-flex board, tube shell and place light receiving component group in the tube shell, rigid-flex board includes DC soft board including DC interface, RF soft board including RF interface and hard board, the tail of DC soft board and RF soft board are pressed and connected through hard board, and the rigid-flex board combination area and the tube shell are welded and fixed, and the light receiving component group is placed in the tube shell. The tail portion of the rigid-flex board enters the tube shell, a gold thread binding area is arranged on the rigid-flex board entering the tube shell, the light receiving component set is electrically connected with the gold thread binding area through gold wire bonding, an optical fiber through hole is formed in the rear portion of the tube shell, and the light receiving component set comprises a plurality of signal transmission channels, a ceramic substrate, a TEC module and a thermistor. According to the utility model, the rigid-flex board is directly connected to the tube shell and participates in gold wire bonding, so that the requirement of the optical receiving assembly for multi-channel small size is ensured, and the problem of poor isolation between channels of the original transition substrate can be solved.

Description

Technical Field

[0001] This utility model relates to the technical fields of quantum communication, quantum computing, lidar, etc., and specifically to an optical receiving component. Background Technology

[0002] In existing optoelectronic modules, the function of the optical transmitting unit (TOSA) is to convert electrical signals into optical signals and transmit them through optical fiber, while the function of the optical receiving unit (ROSA) is to receive the optical signals transmitted through the optical fiber and convert them back into electrical signals. Both TOSA and ROSA modules are generally packaged in TO, BOX, or butterfly packages, with one end being an electrical interface and the other an optical interface. To meet the requirements of higher transmission speeds, the form of the electrical interface is constantly being improved. However, existing electrical interfaces are all built into the housing to achieve both the hermeticity of the housing and the transfer of electrical signals.

[0003] To ensure high bandwidth and high isolation, the electrical interface uses an RF connector integrated with the housing. However, in multi-channel optoelectronic module assembly schemes, the overall size of the optoelectronic module is difficult to reduce due to the size limitations of the RF connector. Therefore, to reduce the overall size, existing solutions use a transition substrate to connect the electrical signals inside and outside the cavity in applications where isolation requirements are not high, such as... Figure 1 and Figure 2 As shown, this ensures the requirements for multi-channel packaging and small size.

[0004] To simultaneously meet the technical requirements of small size and high transmission frequency, existing multi-channel optoelectronic module packages utilize a transition substrate sintered with the housing to provide a microstrip line interface. The electrical signal connection between the packaged optoelectronic module and the PCB board is achieved through an FPC board (…). Figure 1 Or gold wire bonding ( Figure 2 Connect using the following method:

[0005] Impedance discontinuities exist at the connection points between the FPC board and the casing, as well as between the FPC board and the PCB board, leading to bandwidth reduction in high-frequency signal processing. Furthermore, these connections are primarily achieved through soldering, raising reliability concerns. Additionally, conventional methods at these connections cannot achieve complete isolation of the transmission lines, limiting isolation to a maximum of 30dB@10G bandwidth. While gold wire bonding uses only one connection point on each surface, the exposed gold wires in the casing result in poor reliability in practical applications unless overall potting is performed, which increases process complexity. Moreover, the need for gold wire bonding exposes the transmission lines on both the PCB and the casing's transition substrate, indirectly hindering the achievement of high isolation levels for the optoelectronic module assembly. Utility Model Content

[0006] The technical problem to be solved by this invention is how to improve the isolation between channels of a multi-channel optical receiving component.

[0007] This utility model solves the above-mentioned technical problems through the following technical means: an optical receiving component, including a rigid-flex board (1), a housing (2), and an optical receiving component group placed inside the housing (2). The rigid-flex board (1) includes a DC flexible board (12) with a DC interface, an RF flexible board (14) with an RF interface, and a rigid board (16). The tails of the DC flexible board (12) and the RF flexible board (14) are pressed together by the rigid board (16). The rigid-flex board bonding area at the tail of the rigid-flex board (1) is welded and fixed to the housing (2). The tail of the rigid-flex board (1) enters the interior of the housing (2). A gold wire bonding area (19) is provided on the rigid-flex plate (1) inside the tube shell (2). The optical receiving component group is electrically connected to the gold wire bonding area (19) by gold wire bonding. An optical fiber via (22) is opened at the rear of the tube shell (2). The optical receiving component group includes multiple signal transmission channels, a ceramic substrate (42), a TEC module (43), and a thermistor (44). The components of the multiple signal transmission channels, the ceramic substrate (42), and the thermistor (44) are all mounted on the TEC module (43). The TEC module (43) is installed at the bottom of the groove (21) of the tube shell (2).

[0008] As a further optimized technical solution, each signal transmission channel includes a PD chip (412), an integrated resistor-capacitor circuit (413), an FA optical fiber (414), and an independent channel transmission line. The PD chip (412), the integrated resistor-capacitor circuit (413), and the thermistor (44) are all mounted on a ceramic substrate (42), and the ceramic substrate (42) and the FA optical fiber (414) are mounted on the TEC module (43).

[0009] As a further optimized technical solution, the connection structure between the DC flexible board (12) and the optical receiving component group is as follows:

[0010] 1) The DC flexible board (12) and the resistor terminal of the integrated resistor-capacitor circuit (413) are connected by gold wire bonding. The capacitor terminal of the integrated resistor-capacitor circuit (413) is grounded. The node between the resistor and the capacitor is connected to the negative terminal of the PD chip (412) by gold wire bonding.

[0011] 2) The DC flexible board (12) and the positive and negative terminals of the TEC module (43) are connected by gold wire bonding;

[0012] 3) The DC flexible board (12) and the thermistor (44) are connected by gold wire bonding;

[0013] The connection structure between the RF flexible board (14) and the optical receiving component group is as follows:

[0014] The RF flexible board (14) is connected to the ceramic substrate (42) by gold wire bonding, and the ceramic substrate (42) is connected to the positive electrode of the PD chip (412) by gold wire bonding.

[0015] As a further optimized technical solution, the ceramic substrate (32) is close to the rigid-flex plate (1) and is kept horizontal with the RF flexible board (14) of the rigid-flex plate (1).

[0016] As a further optimized technical solution, the top layer of the ceramic substrate (32) adopts the form of a coplanar waveguide GSG, the bottom layer is covered with a ground plane, and the ground planes of the top layer and the bottom layer are connected by vias. The side of the ceramic substrate (32) is metallized to connect the ground planes of the top layer and the bottom layer.

[0017] As a further optimized technical solution, the contact surface between the flexible and rigid plate bonding area at the tail of the flexible and rigid plate (1) and the shell (2) is metallized to form a metallized area (18), and the flexible and rigid plate (1) is welded to the shell (2) through the metallized area (18).

[0018] As a further optimized technical solution, the DC flexible board (12) and the RF flexible board (14) are arranged vertically, and except for the tail pressing area, the other parts between the DC flexible board (12) and the RF flexible board (14) are suspended in the middle.

[0019] As a further optimized technical solution, the gold wire binding area (19) is set in a stepped shape.

[0020] As a further optimized technical solution, the signal routing of the RF flexible board (14) is set as a three-layer board, with the top and bottom layers being ground planes and the middle layer being the signal line. The signal in the middle layer is routed in the manner of coplanar waveguide GSG, and the signal line is shielded around vias.

[0021] In the RF flexible board (14) and DC flexible board (12), the signal lines of the front thermoforming area (13) are routed on the upper surface of the RF flexible board (14) and DC flexible board (12), and the pads on the upper surface of the RF flexible board (14) and DC flexible board (12) are surrounded by a ground plane.

[0022] As a further optimized technical solution, the DC flexible board (12) and the RF flexible board (14) have different lengths.

[0023] The advantages of this utility model are:

[0024] 1) This utility model designs a rigid-flex board for signal transmission and directly connects the rigid-flex board to the tube shell to participate in gold wire bonding. This not only ensures the multi-channel and small size requirements of the optical receiving component, but also solves the problem of poor isolation between channels in the original transition substrate.

[0025] 2) In this utility model, the contact position between the rigid-flexible bonding plate and the tube shell is metallized to ensure the airtightness of the light receiving component.

[0026] 3) The external electrical interface of the rigid-flex board is designed with a two-layer structure, namely a DC interface flexible board and an RF interface flexible board, which are of different lengths to facilitate external installation.

[0027] 4) The DC flexible board and RF flexible board of the rigid-flex board participate in the signal connection inside the casing respectively. Ground planes are designed on the top and bottom layers of the ceramic substrate and connected by vias to further improve the isolation between channels. Attached Figure Description

[0028] Figure 1 This is a structural diagram of an existing optoelectronic module assembly that uses a transition substrate packaging method and an FPC board for electrical connection.

[0029] Figure 2 This is a structural diagram of an existing optoelectronic module assembly that uses a transition substrate packaging method and gold wire bonding for electrical connection.

[0030] Figure 3 This is an overall cross-sectional view of the rigid-flex PCB encapsulation method used in this embodiment of the utility model;

[0031] Figure 4 This is a structural diagram of the rigid-flexible bonding plate in an embodiment of this utility model;

[0032] Figure 5This is a structural diagram of the ROSA component in an embodiment of this utility model;

[0033] Figure 6 This is an internal cross-sectional view of the ROSA component in an embodiment of this utility model;

[0034] Figure 7 This is a layout diagram of the components in each channel of the ROSA component in this embodiment of the present invention;

[0035] Figure 8 This is a connection diagram of the optical receiving component and PCB using a rigid-flex PCB encapsulation in this embodiment of the present invention. Detailed Implementation

[0036] To make the objectives, technical solutions, and advantages of the embodiments of this utility model clearer, the technical solutions of the embodiments of this utility model will be clearly and completely described below in conjunction with the embodiments of this utility model. Obviously, the described embodiments are only some embodiments of this utility model, not all embodiments. Based on the embodiments of this utility model, all other embodiments obtained by those skilled in the art without creative effort are within the protection scope of this utility model.

[0037] It should be noted that, unless otherwise specified, the following embodiments and features can be combined with each other. Furthermore, the illustrations provided in the following embodiments are merely schematic representations of the basic concept of this utility model. The illustrations only show components relevant to this utility model and are not drawn according to the actual number, shape, and size of the components in implementation. In actual implementation, the form, quantity, and proportion of each component can be arbitrarily changed, and the component layout may also be more complex.

[0038] It should be noted that the directional terms mentioned in the embodiments, such as "up," "down," "front," "back," "left," and "right," are only for reference to the directions in the accompanying drawings and are not intended to limit the scope of protection of this disclosure. Throughout the drawings, the same elements are represented by the same or similar reference numerals. Conventional structures or constructions will be omitted where they may cause confusion in understanding this disclosure.

[0039] The use of ordinal numbers such as "first," "second," "third," etc., in the specification and claims to modify the corresponding elements does not imply that the element has any ordinal number, nor does it represent the order of one element with another element, or the order of manufacturing methods. The use of these ordinal numbers is only to enable a named element to be clearly distinguished from another element with the same name.

[0040] Example 1

[0041] This embodiment proposes a multi-channel optoelectronic module assembly with an integrated FPC flexible board and housing packaging method, suitable for packaging multi-channel array optical transmitting and receiving components. For high-speed transceiver components, their external electrical interfaces are divided into DC interfaces and RF (radio frequency) interfaces. In this embodiment, the DC interface and RF interface are respectively fabricated on two FPC flexible boards. The two FPC flexible boards are laminated together at the rear middle by a rigid board (such as FR4, the material of the rigid board is not limited), such as... Figure 3 and Figure 4 As shown, a rigid-flex board 1 containing both DC and RF interfaces is formed. A metallized area 18 is formed at the contact surface between the rigid-flex board 1 and the housing 2 at the rear of the rigid-flex board 1, facilitating welding between the rigid-flex board 1 and the housing 2 and ensuring airtightness. The rear of the rigid-flex board 1 enters the housing 2, where it participates in gold wire bonding. A mounting slot 21 is provided inside the housing 2 to accommodate transceiver components, and a fiber optic via 22 is provided at the rear of the housing 2 for fiber optic connection.

[0042] The rigid-flex board 1 includes a DC flexible board 12, an RF flexible board 14, and a rigid board 16 arranged vertically. The DC flexible board 12 and the RF flexible board 14 are pressed together at their ends by the rigid board 16, while the rest of the DC flexible board 12 and the RF flexible board 14 are suspended in the middle. The rigid board 16 mainly provides support for the two flexible boards and can participate in the encapsulation of the housing 2. Metallization is performed around the pressing area of ​​the rigid-flex board 1 to form a metallized area 18, which facilitates welding with the housing 2 and ensures the airtightness of the housing 2.

[0043] A gold wire bonding area 19 is provided at the tail of the rigid-flex board 1 inside the housing 2. The gold wire bonding area 19 is stepped. The upper layer of the stepped area is the signal connection area of ​​the DC flexible board 12, which realizes the signal connection of DC bias signal, thermoelectric cooler (TEC) drive signal, thermistor, and backlight detector. Only the connectivity and current carrying capacity need to be ensured. The lower layer of the stepped area is the connection area of ​​the RF flexible board 14, which realizes the radio frequency signal. The signal wiring of the RF flexible board 14 is set as a three-layer board. The top and bottom layers are ground planes, and the middle layer is used for signal lines. The signal lines in the middle layer are routed in the form of coplanar waveguide GSG. The signal lines are shielded by vias to ensure the isolation between signals inside the RF flexible board 14. In the RF flexible board 14 and DC flexible board 12, the signal lines of the front thermoforming area 13 will be routed on the upper surface of the RF flexible board 14 and DC flexible board 12. Therefore, in order to avoid the risk of signal leakage when connected to the user's PCB board, the pads on the upper surface of the RF flexible board 14 and DC flexible board 12 are also wrapped with a ground plane.

[0044] Example 2

[0045] This embodiment provides a ROSA assembly employing the rigid-flex PCB 1 structure and the rigid-flex PCB 1 and housing 2 encapsulation structure described in Embodiment 1.

[0046] like Figure 5 and Figure 6 As shown, the ROSA assembly includes a rigid-flex board 1, a housing 2, and an optical receiving component group placed inside the slot 21 of the housing 2. The optical receiving component group is electrically connected to the gold wire bonding area 19 at the tail of the rigid-flex board 1 through gold wire bonding. The optical receiving component group is connected to the optical fiber through the optical fiber via 22 opened at the rear of the housing 2.

[0047] The optical receiving component assembly includes multiple signal transmission channels, a ceramic substrate 42, a TEC module 43, and a thermistor 44. Taking an 8-channel signal transmission channel as an example, each channel includes a PD (photodetector) chip 412, an integrated resistor-capacitor circuit 413, an FA fiber (optical fiber array) 414, and an independent transmission line. The PD chip 412, the integrated resistor-capacitor circuit 413, and the thermistor 44 are all mounted on the ceramic substrate 42, as shown in the specific layout. Figure 7 As shown, the ceramic substrate 42 and the FA optical fiber 414 are both mounted on the TEC module 43, which is mounted at the bottom of the slot 21 of the housing 2. The entire optical receiving component group uses a TEC module 43 and a thermistor 44 to meet the internal temperature control requirements of the cavity. The externally input optical signal is directly coupled to the photosensitive surface of the PD chip 412 through the FA optical fiber 414. After receiving the optical signal, the PD chip 412 converts it into an electrical signal, which is then output through the ceramic substrate 42 and the RF flexible board 14.

[0048] The PD chip 412 can be made of InGaAs / InP material and coplanar GS electrodes. This chip is suitable for optical receiver applications, with an operating data rate of up to 10Gbps, and can transmit optical signals with wavelengths from 920nm to 1650nm in single-mode optical fiber. The integrated RC circuit 413 includes a resistor and a capacitor connected in series.

[0049] The connection between the DC flexible board 12 and RF flexible board 14 of the rigid-flex board 1 in the ROSA assembly and the optical receiving component group inside the housing 2 is described as follows:

[0050] Connection structure between DC flexible board 12 and optical receiving component group:

[0051] 1) The DC flexible board 12 is connected to the resistor terminal of the integrated RC circuit 413 by gold wire bonding. The capacitor terminal of the integrated RC circuit 413 is grounded. The node between the resistor and the capacitor is connected to the negative terminal of the PD chip 412 by gold wire bonding to provide a DC bias signal.

[0052] 2) Connect the DC flexible board 12 to the positive and negative terminals of the TEC module 43 by gold wire bonding to provide the drive current for the TEC module 43;

[0053] 3) The DC flexible board 12 is connected to the thermistor 44 by gold wire bonding to realize the temperature detection inside the tube shell 2.

[0054] Connection structure between RF flexible board 14 and optical receiver component group:

[0055] The RF flexible board 14 is connected to the ceramic substrate 42 by gold wire bonding, and the ceramic substrate 42 is connected to the positive terminal of the PD chip 412 by gold wire bonding. After the external optical signal is coupled to the PD chip 412 through the FA optical fiber 414, it is converted into an electrical signal, and then the electrical signal is output through the ceramic substrate 42 and the RF flexible board 14.

[0056] Compared to traditional solutions, the ROSA component packaging proposed in this invention does not use a transition substrate on the casing. Instead, the rigid-flex board 1 is directly integrated into the casing 2 to participate in gold wire bonding and hermetic encapsulation. This maximizes the low transmission loss of RF signals while also facilitating isolation design, achieving a high level of isolation.

[0057] The assembly of this ROSA component includes the following steps:

[0058] 1) The rigid-flexible bonding plate 1 is connected to the tube shell 2 by welding;

[0059] 2) Weld the internal TEC module 43 to the shell 2 (or bond it, as long as the thermal conductivity is guaranteed);

[0060] 3) The ceramic substrate 42 is mounted on the upper surface of the TEC module 43, close to the rigid-flex board 1, and kept horizontal with the RF flexible board 14 of the rigid-flex board 1, in order to reduce the length of the gold wire bonding leads and ensure radio frequency performance.

[0061] 4) Install the PD chip 412 and the thermistor 44 on the ceramic substrate 42 at the specified positions (by means of bonding with conductive adhesive or eutectic bonding);

[0062] 5) The corresponding signals are connected by gold wire bonding, mainly including the connection of the ceramic substrate 42 to the RF flexible board 14 of the rigid-flex board 1, the connection of the DC flexible board 12 of the rigid-flex board 1 to the TEC module 43, the thermistor 44, and the integrated RC circuit 413, the connection of the ceramic substrate 42 to the PD chip 412, and the connection of the PD chip 412 to the integrated RC circuit 413.

[0063] 6) Apply a bias voltage to the PD chip 412 via the DC board 12 of the rigid-flex board 1 for coupling calibration. In this invention, a source meter is used to apply pressure, and the photocurrent of the PD chip 412 can be observed simultaneously, ensuring the PD chip 412 is in working condition. A test optical signal is input through the tail flange of the FA fiber 414. The FA fiber 414 is moved using a coupling alignment frame for optical path coupling calibration. The photocurrent value of the source meter is observed; when the photocurrent value is at its maximum, coupling is complete. Then, the FA fiber 414 is fixed to the upper surface of the TEC module 43 using adhesive. The FA fiber 414 extends to the outside of the cavity through the fiber optic via 22, which is then sealed with adhesive. Alternatively, if the FA fiber 414 is metallized, the fiber optic via 22 can also be sealed with solder.

[0064] 7) Install the top cover to complete product assembly.

[0065] Example 3

[0066] This embodiment provides an application of an optical receiver component. The external electrical interface of the optical receiver component is a microstrip line RF interface designed according to its characteristic impedance, such as... Figure 8 As shown, it needs to be connected to the user's PCB board 100 by direct soldering, for example, using a thermoforming process. Furthermore, the DC flexible board 12 and RF flexible board 14 on the optical receiving component are soldered to the front and back sides of the PCB board 100, respectively.

[0067] The DC flexible board 12 and RF flexible board 14 of the rigid-flex board 1 have different lengths because it is designed so that users can use through-hole technology in the soldering area when designing the PCB board 100. Otherwise, since there are pads on both sides of the PCB board 100, through-holes cannot be designed when routing high-density traces, and only buried blind holes can be used, which will increase the manufacturing process of the PCB board 100.

[0068] In addition, the external signal line interface on the RF flexible board 14 adopts the method of the signal line being wrapped by the external ground plane. In this way, after the RF flexible board 14 is soldered to the PCB board 100, the signal line will be included in the ground plane, forming effective signal isolation.

[0069] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. Such modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of this utility model.

Claims

1. An optical receiving assembly, characterized by: The application relates to a soft and hard combined board (1), a tube shell (2) and a light receiving component group arranged in the tube shell (2), wherein the soft and hard combined board (1) comprises a DC soft board (12) comprising a DC interface, an RF soft board (14) comprising an RF interface and a hard board (16), tail portions of the DC soft board (12) and the RF soft board (14) are connected by press fitting of the hard board (16), a soft and hard board combination area of the tail portion of the soft and hard combined board (1) is welded and fixed with the tube shell (2), the tail portion of the soft and hard combined board (1) enters the inside of the tube shell (2), a gold wire binding area (19) is arranged on the soft and hard combined board (1) entering the inside of the tube shell (2), the light receiving component group is electrically connected with the gold wire binding area (19) through gold wire bonding, an optical fiber via hole (22) is formed at the rear portion of the tube shell (2), the light receiving component group comprises a plurality of signal transmission channels, a ceramic substrate (42), a TEC module (43) and a thermistor (44), wherein the plurality of signal transmission channels, the ceramic substrate (42) and the thermistor (44) are all arranged on the TEC module (43), and the TEC module (43) is arranged on the bottom of a groove (21) of the tube shell (2).

2. An optical receiving assembly as claimed in claim 1, characterized in that: Each signal transmission channel comprises a PD chip (412), a resistance and capacitance integrated circuit (413), an FA optical fiber (414) and an independent channel transmission line, wherein the PD chip (412), the resistance and capacitance integrated circuit (413) and the thermistor (44) are all arranged on the ceramic substrate (42), and the ceramic substrate (42) and the FA optical fiber (414) are arranged on the TEC module (43).

3. An optical receiving assembly as claimed in claim 2, characterized in that: The connection structure of the DC soft board (12) and the light receiving component group is as follows: 1) the DC soft board (12) and the resistance end of the resistance and capacitance integrated circuit (413) are connected through gold wire bonding, the capacitance end of the resistance and capacitance integrated circuit (413) is grounded, and the node between the resistance and the capacitance is connected with the negative electrode of the PD chip (412) through gold wire bonding; 2) the DC soft board (12) and the positive and negative ends of the TEC module (43) are connected through gold wire bonding; 3) the DC soft board (12) and the thermistor (44) are connected through gold wire bonding; The connection structure of the RF soft board (14) and the light receiving component group is as follows: The RF soft board (14) and the ceramic substrate (42) are connected through gold wire bonding, and the ceramic substrate (42) and the positive electrode of the PD chip (412) are connected through gold wire bonding.

4. An optical receiving assembly as claimed in claim 1, characterized in that: The ceramic substrate (42) is close to the soft and hard combined board (1) and is kept horizontal with the RF soft board (14) of the soft and hard combined board (1).

5. An optical receiving assembly as claimed in claim 1, characterized in that: The top layer of the ceramic substrate (42) adopts the form of a coplanar waveguide GSG, the bottom layer is paved with a ground plane, and the ground planes of the top layer and the bottom layer are connected through a via hole, the side surface of the ceramic substrate (42) is metallized and used for connecting the ground planes of the top layer and the bottom layer.

6. An optical receiving assembly as claimed in claim 1, characterized in that: The soft and hard board combination area of the tail portion of the soft and hard combined board (1) is metallized to form a metallized area (18) with the contact surface of the tube shell (2), and the soft and hard combined board (1) is welded with the tube shell (2) through the metallized area (18).

7. An optical receiving assembly as claimed in claim 1, characterized in that: The DC soft board (12) and the RF soft board (14) are arranged in up and down, and the DC soft board (12) and the RF soft board (14) are suspended in the middle of other parts except the tail compression area.

8. An optical receiving assembly as claimed in claim 1, characterized in that: The gold wire binding area (19) is arranged in a step shape.

9. An optical receiving assembly as claimed in claim 1, characterized in that: The signal wiring of the RF soft board (14) is arranged in a three-layer board, the upper and lower layers are ground planes, the middle layer is a signal line, and the middle layer signal is wired in a coplanar waveguide GSG mode, and the signal line is shielded by using a via hole; In the RF soft board (14) and the DC soft board (12), the signal line of the hot-press welding area (13) located in the front part is wired on the upper surface layer of the RF soft board (14) and the DC soft board (12), and the periphery of the pad on the upper surface layer of the RF soft board (14) and the DC soft board (12) is wrapped with a ground plane.

10. An optical receiving assembly as claimed in claim 1, characterized in that: The length of the DC soft board (12) is inconsistent with that of the RF soft board (14).

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