CN113946019B

CN113946019B - Optical module

Info

Publication number: CN113946019B
Application number: CN202010681155.1A
Authority: CN
Inventors: 张加傲; 王欣南; 慕建伟
Original assignee: Hisense Broadband Multimedia Technology Co Ltd
Current assignee: Hisense Broadband Multimedia Technology Co Ltd
Priority date: 2020-07-15
Filing date: 2020-07-15
Publication date: 2022-11-29
Anticipated expiration: 2040-07-15
Also published as: CN113946019A

Abstract

The application provides an optical module, includes: the circuit board comprises a top layer, a bottom layer and an inner layer positioned between the top layer and the bottom layer, wherein the top layer, the bottom layer and the inner layer are all provided with circuit wiring; the golden finger assembly is arranged at the first end of the circuit board, is positioned on the top layer or the bottom layer, and comprises a plurality of grounding golden fingers and a plurality of high-frequency signal golden fingers which are isolated from each other and are used for transmitting high-frequency signals, and the grounding golden fingers and the high-frequency signal golden fingers are respectively and electrically connected with corresponding circuit wires; the hollowed area is arranged in the inner layer, and the high-frequency signal golden finger is covered by the projection of the top layer or the bottom layer; and the board edge reference ground is paved on the first end and is perpendicular to the board edge in the length direction of the circuit board, is positioned on the inner layer and is electrically connected with the ground on the circuit board. A board edge reference ground is laid on an inner layer of the first end of the circuit board, and the board edge reference ground is grounded to destroy the propagation of electromagnetic radiation generated by the high-frequency signal golden fingers, so that the crosstalk between channels on the high-frequency signal golden fingers can be reduced.

Description

Optical module

Technical Field

The application relates to the technical field of optical fiber communication, in particular to an optical module.

Background

The optical communication technology can be applied to novel services and application modes such as cloud computing, mobile internet, video and the like. In optical communication, an optical module is a tool for implementing interconversion of optical signals and is one of the key components in optical communication equipment.

In use of the optical module, an electrical interface of the optical module is plugged into a cage of the optical network terminal, the electrical interface connecting connectors in the cage. Specifically, one end of the circuit board in the optical module is provided with a golden finger, one end of the circuit board provided with the golden finger extends out of the electrical interface of the optical module, and when the electrical interface is inserted into the cage of the optical network terminal, the connector is electrically connected with the golden finger in a contact mode.

In order to realize the function of the optical module, the golden finger assembly arranged at one end of the circuit board comprises a grounding golden finger, a golden finger for transmitting power signals, a golden finger for transmitting communication signals and the like, wherein the golden finger for transmitting the communication signals comprises a golden finger for transmitting control signals, a high-frequency signal golden finger and the like. In order to facilitate the connection of the golden fingers and the corresponding connectors, each golden finger needs a certain width, but the size of the optical module circuit board is relatively small, so the golden fingers are arranged more densely. The dense arrangement of the gold fingers will cause the crosstalk between the channels formed at the positions.

Disclosure of Invention

The embodiment of the application provides an optical module, which can reduce crosstalk between channels at golden fingers.

The application provides an optical module, includes:

the circuit board comprises a top layer, a bottom layer and an inner layer positioned between the top layer and the bottom layer, wherein circuit wiring is arranged on the top layer, the bottom layer and the inner layer;

the golden finger assembly is arranged at the first end, is positioned at the top layer or the bottom layer, and comprises a plurality of grounding golden fingers and a plurality of high-frequency signal golden fingers which are isolated from each other and used for transmitting high-frequency signals, wherein the grounding golden fingers and the high-frequency signal golden fingers are respectively and electrically connected with corresponding circuit wires;

the hollowed area is arranged on the inner layer, and the high-frequency signal golden finger is covered by the projection of the top layer or the bottom layer;

the board edge reference ground is paved on the first end of the circuit board, is vertical to the board edge in the length direction of the circuit board, is positioned on the inner layer and is electrically connected with the ground on the circuit board.

The optical module provided by the application comprises a circuit board, a golden finger assembly, a hollowed area and a board edge reference ground. The circuit board comprises a top layer, a bottom layer and an inner layer arranged between the top layer and the bottom layer, wherein the top layer, the bottom layer and the inner layer of the circuit board are respectively provided with circuit wires, and a golden finger assembly is arranged at a first end of the circuit board; the golden finger assembly comprises a grounding golden finger and a high-frequency signal golden finger for transmitting high-frequency signals, the grounding golden finger and the high-frequency signal golden finger are arranged at the first end of the circuit board in an isolated mode, and the grounding golden finger and the high-frequency signal golden finger are respectively electrically connected with corresponding circuit wiring. The hollowed area is arranged on the inner layer of the circuit board, and the high-frequency signal golden finger is covered on the projection of the top layer or the bottom layer of the circuit board; the board edge reference ground is laid on the board edge of the circuit board, is positioned at the first end and is vertical to the length direction of the circuit board, the other board edge reference is positioned on the inner layer of the circuit board, and the board edge reference ground is electrically connected with the ground on the circuit board. The inner layer of the circuit board is provided with a hollowed area for improving the impedance of the high-frequency signal golden finger.

When the optical module is used, the first end of the circuit board is used for extending into a cage of an optical network terminal, so that high-frequency signal golden fingers and the like are densely distributed in the cage of the optical network terminal, when a certain group of high-frequency signal golden fingers transmit high-frequency signals, electromagnetic radiation is generated and is directly transmitted to other high-frequency signal golden fingers, and then signals transmitted by other high-frequency signal golden fingers are interfered; meanwhile, other high-frequency signal golden fingers also generate electromagnetic radiation when transmitting high-frequency signals, and the electromagnetic radiation is directly transmitted to a certain group of high-frequency signal golden fingers, so that interference is generated on signals transmitted by the high-frequency signal golden fingers. In the application, the board edge reference ground is laid on the inner layer of the first end of the circuit board, the board edge reference ground is closer to the edge of the circuit board than the hollowed area, the board edge reference ground is grounded, the transmission of electromagnetic radiation generated by the high-frequency signal golden fingers is damaged, and therefore crosstalk between channels on the high-frequency signal golden fingers can be reduced.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present application, the drawings required for the embodiments or the prior art description will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present application, and it is obvious for those skilled in the art to obtain other drawings without creative efforts.

Fig. 1 is a schematic diagram of a connection relationship of an optical communication terminal;

FIG. 2 is a schematic diagram of an optical network unit;

fig. 3 is a schematic structural diagram of an optical module according to an embodiment of the present disclosure;

FIG. 4 is a schematic diagram of an exploded structure of an optical module according to an embodiment of the present application;

fig. 5 is a schematic view of an internal mechanism of an optical module according to an embodiment of the present disclosure;

fig. 6 is a schematic structural diagram of a circuit board according to an embodiment of the present disclosure;

fig. 7 is a partial schematic structural diagram of a contact connection between a circuit board and a connector when an optical module is inserted into a cage according to an embodiment of the present disclosure;

fig. 8 is a partially exploded view of a first end of a circuit board according to an embodiment of the present disclosure;

fig. 9 is a partially exploded view of a first end of a circuit board according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be described clearly and completely with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only some embodiments of the present application, and not all embodiments. All other embodiments obtained by a person of ordinary skill in the art based on the embodiments in the present application without making any creative effort belong to the protection scope of the present application.

The terminology used herein is for the purpose of describing particular embodiments only and is not intended to be limiting of the application. As used in this application and the appended claims, the singular forms "a," "an," and "the" are intended to include the plural forms as well, unless the context clearly indicates otherwise. It should also be understood that the term "and/or" as used herein refers to and encompasses any and all possible combinations of one or more of the associated listed items.

In the following, some embodiments of the present application will be described in detail with reference to the drawings, and features in the following examples and examples may be combined with each other without conflict.

One of the core links of optical fiber communication is the interconversion of optical and electrical signals. The optical fiber communication uses optical signals carrying information to transmit in information transmission equipment such as optical fibers/optical waveguides, and the information transmission with low cost and low loss can be realized by using the passive transmission characteristic of light in the optical fibers/optical waveguides; in order to establish information connection between information transmission devices such as optical fibers and optical waveguides and information processing devices such as computers, interconversion between electrical signals and optical signals is required.

The optical module realizes the function of interconversion between optical signals and electrical signals in the technical field of optical fiber communication, and interconversion between optical signals and electrical signals is the core function of the optical module. The optical module is electrically connected with an external upper computer through a golden finger on an internal circuit board, and the main electrical connection comprises power supply, I2C signals, data signals, grounding and the like; the optical module realizes optical connection with external optical fibers through an optical interface, the external optical fibers are connected in various ways, and various optical fiber connector types are derived; the method is characterized in that the electric connection is realized by using a golden finger at an electric interface, which becomes the mainstream connection mode of the optical module industry, and on the basis, the definition of pins on the golden finger forms various industry protocols/specifications; the optical connection mode realized by adopting the optical interface and the optical fiber connector has become the mainstream connection mode in the optical module industry, on the basis of the mainstream connection mode, the optical fiber connector also forms various industrial standards, such as an LC interface, an SC interface, an MPO interface and the like, the optical interface of the optical module also has adaptive structural design aiming at the optical fiber connector, and the optical fiber adapters arranged at the optical interface have various types.

Fig. 1 is a schematic diagram of connection relationship of an optical communication terminal. As shown in fig. 1, the connection of the optical communication terminal mainly includes the interconnection among the optical network terminal 100, the optical module 200, the optical fiber 101 and the network cable 103;

one end of the optical fiber 101 is connected with a far-end server, one end of the network cable 103 is connected with local information processing equipment, and the connection between the local information processing equipment and the far-end server is completed by the connection between the optical fiber 101 and the network cable 103; and the connection between the optical fiber 101 and the network cable 103 is completed by the optical network terminal 100 having the optical module 200.

An optical interface of the optical module 200 is externally accessed to the optical fiber 101, and establishes bidirectional optical signal connection with the optical fiber 101; the electrical interface of the optical module 200 is externally connected to the optical network terminal 100, and establishes a bidirectional electrical signal connection with the optical network terminal 100; bidirectional interconversion of optical signals and electric signals is realized inside the optical module, so that information connection is established between the optical fiber and the optical network terminal; specifically, an optical signal from the optical fiber 101 is converted into an electrical signal by an optical module and then input to the optical network terminal 100, and an electrical signal from the optical network terminal 100 is converted into an optical signal by an optical module and input to the optical fiber 101.

The optical network terminal is provided with an optical module interface 102, which is used for accessing an optical module 200 and establishing bidirectional electric signal connection with the optical module 200; the optical network terminal has a network cable interface 104, which is used for accessing the network cable 103 and establishing a bidirectional electrical signal connection (generally, an electrical signal of an ethernet protocol, which is different from an electrical signal used by an optical module) with the network cable 103; the optical module 200 is connected to the network cable 103 through the optical network terminal 100, specifically, the optical network terminal transmits a signal from the optical module to the network cable and transmits the signal from the network cable to the optical module, and the optical network terminal serves as an upper computer of the optical module to monitor the operation of the optical module. The optical network terminal is an upper computer of the optical module, provides data signals for the optical module, and receives the data signals from the optical module, so that a bidirectional signal transmission channel is established between the remote server and the local information processing equipment through the optical fiber, the optical module, the optical network terminal and the network cable.

Common local information processing apparatuses include routers, home switches, electronic computers, and the like; common optical network terminals include an optical network unit ONU, an optical line terminal OLT, a data center server, a data center switch, and the like.

Fig. 2 is a schematic diagram of an optical network terminal structure. As shown in fig. 2, the optical network terminal 100 includes a circuit board 105, and a cage 106 is disposed on a surface of the circuit board 105; an electrical connector is arranged inside the cage 106 and used for connecting an electrical interface (such as a gold finger) of an optical module; the cage 106 is provided with a heat sink 107, and the heat sink 107 has a projection such as a fin that increases a heat radiation area.

The optical module 200 is inserted into an optical network terminal, the electrical interface of the optical module is inserted into the electrical connector inside the cage 106, and the optical interface of the optical module is connected to the optical fiber 101.

The cage 106 is positioned on the circuit board, and the electrical connector on the circuit board is wrapped in the cage, so that the electrical connector is arranged in the cage; the optical module is inserted into the cage, held by the cage, and the heat generated by the optical module is conducted to the cage 106 and then diffused by the heat sink 107 on the cage.

Fig. 3 is a schematic view of an optical module according to an embodiment of the present disclosure, and fig. 4 is an exploded schematic view of an optical module according to an embodiment of the present disclosure. As shown in fig. 3 and 4, an optical module 200 provided in an embodiment of the present application includes an upper housing 201, a lower housing 202, an unlocking member 203, a circuit board 300, a tosa 206, a rosa 207, an optical fiber adapter 208, and an optical fiber 209.

The upper shell 201 is covered on the lower shell 202 to form a wrapping cavity with two openings; the outer contour of the wrapping cavity is generally a square body, and specifically, the lower shell comprises a main plate and two side plates which are positioned at two sides of the main plate and are perpendicular to the main plate; the upper shell comprises a cover plate, and the cover plate covers two side plates of the upper shell to form a wrapping cavity; the upper shell can also comprise two side walls which are positioned at two sides of the cover plate and are perpendicular to the cover plate, and the two side walls are combined with the two side plates to realize that the upper shell covers the lower shell.

The two openings can be two ends (204, 205) in the same direction, or two openings in different directions; one opening is an electric port 204, and a gold finger of the circuit board extends out of the electric port 204 and is inserted into an upper computer such as an optical network terminal; the other opening is an optical port 205 for external optical fiber access; the optoelectronic devices such as the circuit board 300, the tosa 206, and the rosa 207 are located in the package cavity formed by the upper and lower shells.

The assembly mode of combining the upper shell 201 and the lower shell 202 is adopted, so that the devices such as the light emission sub-module 206, the light receiving sub-module 207, the optical fiber adapter 208, the optical fiber 209 and the like can be conveniently installed in the shells, and the upper shell 201 and the lower shell 202 form an outermost packaging protection shell of the optical module; the upper shell 201 and the lower shell 202 are generally made of metal materials, which is beneficial to realizing electromagnetic shielding and heat dissipation; generally, the housing of the optical module is not made into an integrated component, so that when devices such as a circuit board and the like are assembled, the positioning component, the heat dissipation component and the electromagnetic shielding component cannot be installed, and the production automation is not facilitated.

The unlocking component 203 is located on the outer wall of the wrapping cavity/lower shell 202, and is used for realizing the fixed connection between the optical module and the upper computer or releasing the fixed connection between the optical module and the upper computer.

The unlocking component 203 is provided with a clamping component matched with the upper computer cage; the end of the unlocking component is pulled to enable the unlocking component to move relatively on the surface of the outer wall; the optical module is inserted into a cage of the upper computer, and the optical module is fixed in the cage of the upper computer by a clamping component of the unlocking component; by pulling the unlocking component, the clamping component of the unlocking component moves along with the unlocking component, so that the connection relation between the clamping component and the upper computer is changed, the clamping relation between the optical module and the upper computer is released, and the optical module can be drawn out from the cage of the upper computer.

The tosa and the rosa may be collectively referred to as an optical subassembly. As shown in fig. 4, the optical module provided in the embodiment of the present application includes an tosa 206 and an rosa 207, and the tosa 206 and the rosa 207 are electrically connected to a circuit board 300. Optionally, the tosa 206 and the rosa 207 are located at an end of the circuit board 300, and the tosa 206 and the rosa 207 are physically separated from the circuit board 300. The tosa 206 and the rosa 207 may be connected to the circuit board 300 through flexible circuit boards, respectively.

In the optical module provided by the embodiment of the application, the optical fiber adapters 208 and the optical fibers 209 are included, for convenience of description, the optical fiber 209 connected with the optical transmit sub-module 206 is referred to as a first optical fiber, the optical fiber 209 connected with the optical receive sub-module 207 is referred to as a second optical fiber, the optical fiber adapter 208 connected with the first optical fiber is referred to as a first optical fiber adapter, and the optical fiber adapter 208 connected with the second optical fiber is referred to as a second optical fiber adapter. The number of the first optical fiber, the second optical fiber, the first fiber adapter and the second fiber adapter is more than one, and the specific number needs to be combined with the number of the tosa 206 and the rosa 207. Typically, an optical transmit sub-assembly 206 corresponds to a first optical fiber and a first fiber optic adapter, and an optical receive sub-assembly 207 corresponds to a second optical fiber and a second fiber optic adapter.

As shown in fig. 4, the optical module provided in this embodiment includes two tosas 206 and two tosas 207, so the optical module includes 4 optical fiber adapters 208 and 4 optical fibers 209, two first optical fibers and two first optical fiber adapters are used for the two tosas 206, and two second optical fibers and two second optical fiber adapters are used for the two tosas 207.

One end of the first optical fiber adapter is connected with the tosa 206 through a first optical fiber, and the other end is connected with an external optical fiber, so that the signal light generated by the tosa is output to the external optical fiber through the first optical fiber; one end of the second optical fiber adapter is connected to the optical receive sub-module 207 through a second optical fiber, and the other end is connected to an external optical fiber, so that signal light from the outside of the optical module is transmitted to the second optical fiber through the external optical fiber and transmitted to the optical receive sub-module 207 through the second optical fiber.

The circuit board 300 is provided with circuit traces, electronic components (such as capacitors, resistors, triodes, and MOS transistors), and chips (such as an MCU, a clock data recovery CDR, a power management chip, and a data processing chip DSP).

The circuit board 300 connects the electrical devices in the optical module together according to circuit design through circuit wiring to realize power supply, electrical signal transmission, grounding and other electrical functions.

The circuit board is generally a rigid circuit board, and the rigid circuit board can also realize a bearing effect due to relatively hard materials of the rigid circuit board, for example, the rigid circuit board can stably bear a chip; when the optical transceiver is positioned on the circuit board, the rigid circuit board can also provide stable bearing; the hard circuit board can also be inserted into an electric connector in the upper computer cage, and specifically, a metal pin/golden finger is formed on the surface of the tail end of one side of the hard circuit board and is used for being connected with the electric connector; these are not easily implemented with flexible circuit boards.

A flexible circuit board is also used in a part of the optical module to supplement a rigid circuit board; the flexible circuit board is generally used in combination with a rigid circuit board, for example, the rigid circuit board may be connected to the optical transceiver device by using the flexible circuit board.

Fig. 5 is a schematic diagram of an internal structure of an optical module provided in an embodiment of the present application, and fig. 6 is a schematic diagram of a structure of a circuit board provided in the embodiment of the present application. As shown in fig. 5 and 6, the circuit board 300 provided in the embodiment of the present application includes a first end 310, and a gold finger assembly 320 is disposed on the first end 310. The circuit board 300 includes two surfaces with relatively large areas and opposite positions, and for convenience of description, one of the surfaces is referred to as a top layer of the circuit board 300, and the other surface is referred to as a bottom layer of the circuit board 300; the gold finger assembly 320 is disposed more than on the top layer of the circuit board 300, and the gold finger assembly 320 is also disposed on the bottom layer of the circuit board 300 opposite to the top layer shown in fig. 5 and 6. For convenience of description, in the embodiment of the present application, the gold finger assembly 320 includes a first group of gold fingers and a second group of gold fingers, and the first group of gold fingers and the second group of gold fingers respectively include a plurality of gold fingers. Optionally, the first group of gold fingers is disposed on the top layer of the circuit board 300, and the second group of gold fingers is disposed on the bottom layer of the circuit board 300.

The gold finger assembly 320 comprises a plurality of gold fingers isolated from each other, and the plurality of gold fingers isolated from each other comprise a gold finger for grounding, a gold finger for transmitting a power signal and a gold finger for transmitting a communication signal. The golden finger for transmitting the power signal is used to enable the power device on the circuit board 300 to be powered on for operation, and the golden finger for transmitting the communication signal is used to enable the golden finger to perform communication signal transmission, so although the golden finger for transmitting the communication signal is also used to substantially transmit an electrical signal, the function of the electrical signal transmitted by the golden finger for transmitting the communication signal is different from the function of the electrical signal transmitted by the golden finger for transmitting the power signal. It should be noted that the signal type transmitted by the gold finger for transmitting the communication signal may specifically be a control signal, a high-frequency signal, a clock signal, or the like, and further, the gold finger for transmitting the communication signal includes the gold finger for transmitting the high-frequency signal.

For convenience of description, in the embodiments of the present application, a gold finger used for grounding is referred to as a grounding gold finger, and a gold finger used for transmitting a high-frequency signal is referred to as a high-frequency signal gold finger. In the embodiment of the present invention, the circuit board 300 is provided with circuit traces such as ground, high-frequency signal lines, etc., and the golden fingers in the golden finger assembly 320 are electrically connected to the corresponding circuit traces, respectively. For example, the grounding fingers are connected to the ground on the circuit board 300, and the high-frequency signal fingers are electrically connected to the corresponding high-frequency signal lines on the circuit board 300.

In the embodiment of the present application, since the optical module 200 has a small structural volume, and in order to meet the requirement of mounting the circuit board 300 in the housing of the optical module 200, the size of the corresponding circuit board 300 is relatively smaller, so that in order to meet the requirement of laying out the circuit area on the circuit board 300, the circuit board 300 is a multi-layer circuit board, and further, the circuits of the circuit board 300 are integrally laid out on each layer of the circuit board 300. The number of layers of the circuit board 300 can be selected according to the actual requirements of the circuit layout, and adjacent layers are isolated from each other by an insulating material. Alternatively, the number of layers of the circuit board 300 may be 5, 8, 10, etc.

In the embodiment of the present application, the circuit board 300 includes a top layer, a bottom layer, and a plurality of inner layers located between the top layer and the bottom layer, and each layer has a circuit trace disposed thereon. The inner layers typically include multiple layers, such as 10 layers for circuit board 300 and 8 layers for the inner layers. The gold fingers in the gold finger assembly 320 are disposed on the top and bottom layers of the circuit board 300. If the golden finger needs to be connected with a circuit trace located on the top layer or the bottom layer of the circuit board 300, the circuit trace directly extends to the corresponding golden finger; if the golden finger needs to be connected with the circuit trace located in the inner layer of the circuit board 300, the circuit trace directly extends to the projection area of the corresponding golden finger on the inner layer of the circuit board 300, and then the corresponding golden finger is electrically connected through the metal via hole. If a certain circuit trace is the third layer of the circuit board 300 and the corresponding gold finger is located on the top layer of the circuit board 300, the circuit trace extends to the projection area of the corresponding gold finger on the third layer of the circuit board 300, and a via hole from the top layer to the third layer is arranged in the projection area of the corresponding gold finger of the circuit board 300, and the circuit trace is electrically connected to the corresponding gold finger through the via hole; the number of vias typically includes several.

Fig. 7 is a schematic partial structural diagram of a contact connection between a circuit board and a connector when an optical module provided in an embodiment of the present application is inserted into a cage. As shown in fig. 7, the gold fingers of the gold finger assembly 320 are disposed on the top layer 301 and the bottom layer 302 of the circuit board 300, and when the optical module is inserted into the cage, the gold fingers at the first end of the circuit board 300 are electrically connected to the corresponding connectors in a contacting manner.

As shown in fig. 7, the circuit board 300 provided in this embodiment is a 10-layer board, that is, the circuit board 300 includes 10 metal layers for disposing circuit traces. Specifically, the circuit board 300 comprises a top layer 301, a bottom layer 302 and an inner layer 303 arranged between the top layer 301 and the bottom layer 302, wherein the top layer 301 is a first layer of the circuit board 300, the bottom layer 302 is a tenth layer of the circuit board 300, and then the inner layers 303 comprise a second layer, a third layer and a fourth layer of the circuit board 300, wherein the fourth layer is 8230the third layer is 8230the eighth layer and the ninth layer is the ninth layer. The top layer 301, the second layer 8230, the ninth layer 8230, the bottom layer 302 are sequentially stacked and arranged, and adjacent layers are mutually isolated through insulating materials. As the top layer 301, the second layer 8230, the ninth layer 302 and the bottom layer 302 are thinner, the structure of one layer in the circuit board 300 shown in FIG. 7 is mainly formed by insulating materials, and the second layer 8230, the ninth layer 8230and the ninth layer are respectively clamped between corresponding structure layers formed by the insulating materials. Wherein the shaded areas on the top layer 301 in fig. 7 are circuit traces formed by copper.

In the embodiment of the application, the connector comprises a connector G for connecting the grounding golden finger and a connector S for connecting the high-frequency signal golden finger, and the connector G is in contact connection with the corresponding golden finger below the connector S. In the local circuit board 300 shown in fig. 7, the number of the connectors G and S connected to the local circuit board is not more than one, and the number of the grounding fingers and the number of the high-frequency signal fingers are not more than one. In this embodiment, the grounding gold finger and the high-frequency signal gold finger are electrically connected to corresponding circuit traces on the circuit board 300, respectively.

The circuit traces electrically connected to the grounding fingers and the high-frequency signal fingers on the top layer 301 of the circuit board 300 shown in fig. 7 are located on the top layer 301 of the circuit board 300, but the circuit traces are not limited to the top layer 301 of the circuit board 300 in the embodiment of the present invention, for example, the circuit traces electrically connected to the grounding fingers or the high-frequency signal fingers on the top layer 301 may be located on the inner layer 303. If the circuit trace electrically connected to the grounding gold finger or the high-frequency signal gold finger on the top layer 301 can be located on the inner layer 303, the circuit trace is extended to the projection area of the gold finger on the inner layer 303, a metal via hole from the gold finger to the projection area is arranged, and the circuit trace and the gold finger are electrically connected through the metal via hole. Accordingly, the circuit traces on the bottom layer 302 to which the grounding fingers or the high-frequency signal fingers are electrically connected may be located on the bottom layer 302 and may also be located on the inner layer 303.

In the embodiment of the present application, in order to improve the impedance of the high-frequency signal gold finger, etc. is provided with a hollowed area in the projection area of the inner layer 303 of the circuit board 300. The hollowed area means that the area is at most provided with circuit wires connected with corresponding golden fingers, and other metals are not laid (other circuit wires are not arranged). In order to fully ensure the effect of the hollowed-out area, the width of the hollowed-out area is greater than or equal to the width of the corresponding high-frequency signal gold finger, and the like, for example, the side edge of the hollowed-out area is located below the grounding gold finger beside the high-frequency signal gold finger, and the length direction extends to the board edge of the circuit board 300 as far as possible, so that the projection of the hollowed-out area on the surface of the circuit board 300 covers the corresponding gold finger as far as possible. Of course, if there is not enough area of the inner layer 303 of the circuit board 300 to realize that the hollowed area completely covers the corresponding gold finger, the corresponding gold finger may not be completely covered. The shape of the hollowed area can be regular or irregular, and the hollowed area can be adjusted according to the paving area of the area and the circuit wiring.

In the high-speed optical module, the golden fingers are arranged relatively densely, so when a certain connector S transmits a high-frequency signal, the connector S and the corresponding high-frequency signal golden finger generate electromagnetic radiation, the electromagnetic radiation is transmitted to other connectors S and other high-frequency signal golden fingers, and if the electromagnetic radiation is transmitted to other connectors S and other high-frequency signal golden fingers, the electromagnetic radiation interferes with signals transmitted on other connectors S and other high-frequency signal golden fingers; accordingly, when the electromagnetic radiation generated by the other connectors S and the other high-frequency signal fingers is transmitted to the certain connector S and the corresponding high-frequency signal fingers, if the electromagnetic radiation generated by the other connectors S and the other high-frequency signal fingers is transmitted to the certain connector S and the corresponding high-frequency signal fingers, the signals transmitted by the certain connector S and the corresponding high-frequency signal fingers will be interfered. Thus, in the using process of the optical module, if the electromagnetic radiation generated by the connector S and the corresponding high-frequency signal golden finger is transmitted to other connectors S and high-frequency signal golden fingers, crosstalk will be generated between the high-frequency signal golden finger and each channel of the connector S. It was found through testing that the inter-channel crosstalk at 20GHz sometimes exceeds-30 dB.

In order to reduce the crosstalk generated between the high frequency signal gold fingers and the channels at the connector S, in the embodiment of the present application, the board edge of the first end 310 of the circuit board 300 is provided with the board edge reference ground 330. The board edge reference ground 330 is disposed on a board edge perpendicular to the length direction of the circuit board 300, i.e. the board edge reference ground 330 is the edge of the first end 310 of the circuit board 300. In order to prevent the board edge reference ground 330 from affecting the arrangement of the gold finger assembly 320, the board edge reference ground 330 is arranged on the inner layer 303 of the circuit board 300. Further, the board edge reference ground 330 is located at the edge of the inner layer 303, that is, the board edge reference ground 330 is located at the edge of the inner layer projection area of the golden finger assembly 320, which is closer to the edge of the inner layer 303 than the hollowed area provided on the inner layer 303. Optionally, the board edge reference ground 330 is in contact with a hollowed-out area of the same layer, such as on the circuit board 300, where the hollowed-out area extends to the board edge reference ground 330 of the same layer.

The board edge reference ground 330 is typically formed by metallization, such as copper, and the board edge reference ground 330 is electrically connected to a ground on the circuit board 300. Electromagnetic radiation generated by the connector S and the corresponding high-frequency signal golden finger is transmitted to the board edge reference ground 330, the board edge reference ground 330 absorbs energy of the electromagnetic radiation, transmission of the electromagnetic radiation is blocked, crosstalk generated between the high-frequency signal golden finger and each channel at the connector S can be further reduced, and the crosstalk between channels of 20GHz is found to be lower than-30 dB through tests. Optionally, a board edge reference ground 330 is provided at each board edge of the inner layer 303. The board edge reference ground 330 on each layer may be connected to a grounding gold finger through a metal via. In order to ensure the effect of suppressing the interference of the board edge reference ground 330, the width of the board edge reference ground 330 is not less than 20 mils.

Fig. 8 is a partially exploded view of a first end of a circuit board according to an embodiment of the present application, and fig. 8 shows a partial structure of a top layer 301 of a circuit board 300. As shown in fig. 8, the gold finger assembly 320 provided in this embodiment includes a segment of gold fingers arranged according to a protocol rule, wherein the gold fingers including a first group of gold fingers include a first high-frequency signal gold finger 321 and a second high-frequency signal gold finger 322. Of course, the first set of fingers may include not only the first high frequency signal fingers 321 and the second high frequency signal fingers 322, but also other high frequency signal fingers. The first high-frequency signal gold finger 321 and the second high-frequency signal gold finger 322 are generally used to transmit differential signals, and therefore gold fingers of the first high-frequency signal gold finger 321 and the second high-frequency signal gold finger 322 are generally present in pairs. As shown in fig. 8, the first group of gold fingers in the gold finger assembly 320 provided by the present embodiment further includes a first grounding gold finger 323, a second grounding gold finger 324, and a third grounding gold finger 325. The first grounding finger 323 is disposed at one side of the first high-frequency signal finger 321, the second grounding finger 324 is disposed at the other side of the first high-frequency signal finger 321, and the third grounding finger 325 is disposed at one side of the second high-frequency signal finger 322 far from the first high-frequency signal finger 321.

Also shown in fig. 8 is a first inner layer 3031 of the circuit board 300, the first inner layer 3031 being a second layer of the circuit board 300. The plate edge of the first inner layer 3031 is provided with a first plate edge reference ground 331. The width of the first board edge with reference to the ground 331 is not less than 20 mils. Correspondingly, the board edge reference ground may also be disposed on other inner layers in the circuit board 300, and the board edge reference ground on the other inner layers may be disposed with reference to the first board edge reference ground 331 on the first inner layer 3031. The plate edges can be directly or indirectly electrically connected with reference to the ground. For example, metal through holes are arranged on the board edge reference ground, and the electric connection between the board edge reference grounds is realized through the corresponding metal through holes. Further, the board edge is electrically connected with the grounding golden finger directly or indirectly with reference to the ground. Specifically, a plurality of metal via holes 3311 are disposed on the first inner layer 3031, and the first board edge reference ground 331 is connected to the board edge reference grounds on the other inner layers through the metal via holes 3311; alternatively, a grounded gold finger on the top layer 301 or the bottom layer 302 is connected.

As shown in fig. 8, a first hollowed-out area 0311 and a second hollowed-out area 0312 are further disposed on the first inner layer 3031, the projection of the first hollowed-out area 0311 on the top layer 301 completely covers the first high-frequency signal gold finger 321, and the projection of the second hollowed-out area 0312 on the top layer 301 completely covers the second high-frequency signal gold finger 322. However, if the area occupied by the wires and the floor space around the first hollowed-out area 0311 and the second hollowed-out area 0312 is large, the area occupied by the first hollowed-out area 0311 and the second hollowed-out area 0312 can be reduced appropriately, so that the projection of the first hollowed-out area 0311 on the top layer 301 does not completely cover the first high-frequency signal gold finger 321, and the projection of the second hollowed-out area 0312 on the top layer 301 does not completely cover the second high-frequency signal gold finger 322. The first hollowed-out area 0311 helps to increase the impedance of the first high frequency signal finger 321, and the second hollowed-out area 0312 helps to increase the impedance of the second high frequency signal finger 322. Optionally, the first hollowed-out area 0311 and the second hollowed-out area 0312 extend to the first plate edge reference ground 331. First hollowed-out area 0311 and second hollowed-out area 0312 may be regular shapes. The first cut-out 0311 may be referenced to as a cut-out on another layer of inner layer 303.

As shown in fig. 8, the width of the first hollow portion 0311 is greater than the width of the first high-frequency signal gold finger 321, and the width of the second hollow portion 0312 is greater than the width of the second high-frequency signal gold finger 322. Optionally, one side of the first hollowed-out region 0311 is located in the projection region of the first grounding finger 323 on the first inner layer 3031, and the other side of the first hollowed-out region 0311 is located in the projection region of the second grounding finger 324 on the first inner layer 3031; one side of the second hollowed-out region 0312 is located in the projection area of the second grounding finger 324 on the first inner layer 3031, and the other side of the second hollowed-out region 0312 is located in the projection area of the third grounding finger 325 on the first inner layer 3031. If the first hollowed area 0311 and the second hollowed area 0312 can be used for routing and paving, the first hollowed area 0311 can be communicated with the second hollowed area 0312.

In addition, a hollowed-out region is also provided in the other inner layer 303 of the circuit board 300. Optionally, hollowed-out regions are provided on consecutive inner layers 303 of the layer adjacent to the high-frequency signal gold finger. For example, the first high-frequency signal gold finger 321 is provided with a first hollow area on the second layer to the fifth layer, the second layer to the eighth layer, and the like of the projection area on the circuit board 300, and the second high-frequency signal gold finger 322 is provided with a second hollow area on the second layer to the fifth layer, the second layer to the ninth layer, and the like of the projection area on the circuit board 300.

Fig. 9 is a partially exploded view of a first end of a circuit board according to an embodiment of the present disclosure, and compared with fig. 8, fig. 9 further shows a second inner layer 3032 of the circuit board 300, where the second inner layer 3032 is a third layer of the circuit board 300. The plate edges of the second inner layer 3032 are provided with a second plate edge reference ground 332. The width of the second plate edge reference ground 332 is not less than 20 mils. A plurality of metal through holes 3321 are arranged on the second board edge reference ground 332, and the second board edge reference ground 332 is connected with the first board edge reference ground 331 or the board edge reference ground on other inner layers through the metal through holes 3321.

As shown in fig. 9, a first hollowed area 0321 and a second hollowed area 0322 are further disposed on the second inner layer 3032, the projection of the first hollowed area 0321 on the top layer 301 covers the first high-frequency signal gold finger 321, and the projection of the second hollowed area 0322 on the top layer 301 covers the second high-frequency signal gold finger 322. First hollowed-out region 0321 helps to further increase the impedance of first high frequency signal finger 321, and second hollowed-out region 0322 helps to further increase the impedance of second high frequency signal finger 322. First hollowed out area 0321 and second hollowed out area 0322 extend to second plate edge reference ground 332.

As shown in fig. 9, the width of the first hollowed-out area 0321 is greater than the width of the first high-frequency signal gold finger 321, and the width of the second hollowed-out area 0322 is greater than the width of the second high-frequency signal gold finger 322. Optionally, one side of the first hollowed-out region 0321 is located in the projection region of the first grounding gold finger 323 on the second inner layer 3032, and the other side of the first hollowed-out region 0321 is located in the projection region of the second grounding gold finger 324 on the second inner layer 3032; one side of the second hollowed area 0322 is located in the projected area of the second grounding finger 324 on the second inner layer 3032, and the other side of the second hollowed area 0322 is located in the projected area of the third grounding finger 325 on the second inner layer 3032.

Accordingly, in the embodiment of the present application, the second group of gold fingers on the bottom layer of the circuit board 300 may include high frequency signal gold fingers such as a third high frequency signal gold finger and a fourth high frequency signal gold finger. The first high frequency signal gold finger 321 is opposite to the third high frequency signal gold finger, and the second high frequency signal gold finger 322 is opposite to the fourth high frequency signal gold finger. The third high-frequency signal gold finger and the fourth high-frequency signal gold finger are also provided with a hollowed area in the projection area of the inner layer 303. For example, the third hollowed regions are disposed on the ninth layer to the sixth layer, the ninth layer to the second layer, and the like of the projection region of the third high-frequency signal gold finger on the circuit board 300, and the fourth hollowed regions are disposed on the ninth layer to the sixth layer, the ninth layer to the second layer, and the like of the projection region of the fourth high-frequency signal gold finger on the circuit board 300.

The second group of gold fingers in the gold finger assembly 320 provided by this embodiment further includes a fourth grounding gold finger, a fifth grounding gold finger and a sixth grounding gold finger. The fourth grounding golden finger is arranged on one side of the third high-frequency signal golden finger, the fifth grounding golden finger is arranged on the other side of the third high-frequency signal golden finger, and the sixth grounding golden finger is arranged on one side, far away from the third high-frequency signal golden finger, of the fourth high-frequency signal golden finger.

The width of the third hollowed area is larger than that of the third high-frequency signal golden finger, and the width of the fourth hollowed area is larger than that of the fourth high-frequency signal golden finger. Optionally, one side of the third hollowed area is located in the projection area of the fourth grounding golden finger on the inner layer, and the other side of the third hollowed area is located in the projection area of the fifth grounding golden finger on the inner layer; one side edge of the fourth hollowed area is located in the projection area of the fifth grounding golden finger on the inner layer, and the other side edge of the fourth hollowed area is located in the projection area of the sixth grounding golden finger on the inner layer.

Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit the same; although the present application has been described in detail with reference to the foregoing embodiments, it should be understood by those of ordinary skill in the art that: the technical solutions described in the foregoing embodiments may still be modified, or some technical features may be equivalently replaced; and such modifications or substitutions do not depart from the spirit and scope of the corresponding technical solutions in the embodiments of the present application.

Claims

1. A light module, comprising:

the circuit board comprises a top layer, a bottom layer and an inner layer positioned between the top layer and the bottom layer, wherein the top layer, the bottom layer and the inner layer are all provided with circuit wiring;

the golden finger assembly is arranged at the first end of the circuit board, is positioned at the top layer or the bottom layer, and comprises a plurality of grounding golden fingers and a plurality of high-frequency signal golden fingers which are isolated from each other and used for transmitting high-frequency signals, wherein the grounding golden fingers and the high-frequency signal golden fingers are respectively and electrically connected with corresponding circuit wires;

the board edge reference ground is paved on the first end edge of the circuit board, is perpendicular to the board edge of the circuit board in the length direction, is positioned on the inner layer and is electrically connected with the ground on the circuit board;

the board edge is disposed referenced between the hollowed-out area and a first end edge of the circuit board.

2. The optical module according to claim 1, wherein the circuit board comprises a plurality of inner layers, the board edges of the inner layers are all provided with the board edge reference ground, and the board edges on the adjacent layers are connected through the metal via holes.

3. The light module of claim 2, wherein the gold finger assembly comprises a first set of gold fingers and a second set of gold fingers;

the first group of golden fingers are arranged on the top layer and comprise first high-frequency signal golden fingers, a plurality of continuous inner layers close to the top layer are provided with first hollowed areas, and the projections of the first hollowed areas on the top layer cover the first high-frequency signal golden fingers;

the second group of golden fingers are arranged on the bottom layer and comprise third high-frequency signal golden fingers, a plurality of continuous inner layers close to the bottom layer are provided with third hollowed areas, and the projections of the third hollowed areas on the bottom layer cover the third high-frequency signal golden fingers.

4. The optical module of claim 2, wherein the board edges are electrically connected to the grounding gold fingers by metal vias with reference to ground, respectively.

5. The optical module of claim 1, wherein the board edge has a width with reference to ground of not less than 20 mils.

6. The optical module according to claim 1, wherein the hollowed-out area extends in a length direction of the circuit board to a board edge reference ground on the same layer as the circuit board, and the hollowed-out area completely covers the corresponding high-frequency signal golden finger.

7. The optical module of claim 1, wherein the width of the hollowed area is greater than the width of the high-frequency signal gold finger.

8. The optical module as claimed in claim 3, wherein the first set of gold fingers further includes a first grounding gold finger, a side of the first high frequency signal gold finger is disposed with the first grounding gold finger, and a projection of the first grounding gold finger on the inner layer covers a side of the first hollowed-out area.

9. The optical module as claimed in claim 3, wherein the second set of gold fingers further includes a fourth grounding gold finger, a side of the third high frequency signal gold finger is disposed with the fourth grounding gold finger, and a projection of the fourth grounding gold finger on the inner layer covers a side of the third hollowed-out area.