WO2023284475A1 - Optical module - Google Patents

Abstract

An optical module, comprising a housing and a circuit board. The circuit board is disposed in the housing and comprise multiple plate layers; the multiple plate layers comprise a top layer, a bottom layer, and at least one intermediate layer between the top layer and the bottom layer; and every two adjacent plate layers are insulated. The circuit board further comprises a ground layer, a signal line, a signal gold finger, a ground wire, a ground gold finger, and a reflow hole. The ground layer is located in the at least one intermediate layer. The signal line is located in the top layer or the bottom layer. The signal gold finger is located in the same plate layer as the signal line and is electrically connected to the signal line. The ground wire is located in the same plate layer as the signal line and is electrically connected to the ground layer. The ground gold finger is located in the same plate layer as the signal line, is electrically connected to the ground wire by means of a ground through hole, and is arranged adjacent to the signal gold finger. The projection of the reflow hole in the at least one intermediate layer is located in the projection of the ground gold finger in the at least one intermediate layer; and the reflow hole has one end that is connected to the ground gold finger but does not run through the ground gold finger and the other end that runs through one or more intermediate layers among the at least one intermediate layer and then is electrically connected to the ground layer.

Description

optical module

This application claims the priority of the Chinese patent application with application number 202121704110.8 submitted on July 26, 2021, and the priority of the Chinese patent application with application number 202121630484.X submitted on July 16, 2021, all of which The contents are incorporated by reference in this application.

technical field

The present disclosure relates to the technical field of optical communication, in particular to an optical module.

Background technique

With the development of cloud computing, mobile Internet, video conferencing and other new business and application models, the development and progress of optical communication technology has become more and more important. In optical communication technology, the optical module is a tool for realizing mutual conversion of photoelectric signals, and is one of the key components in optical communication equipment. With the development of optical communication technology, the transmission rate of optical modules continues to increase.

Contents of the invention

An optical module is provided, and the optical module includes a casing and a circuit board. The circuit board is arranged in the housing, and the circuit board includes a plurality of board layers, and the multiple board layers include a top layer, a bottom layer, and at least one intermediate layer between the top layer and the bottom layer, and each phase Two adjacent plies are insulated from each other. The circuit board also includes a ground layer, a signal wire, a signal gold finger, a ground wire, a ground gold finger and a return hole. The ground plane is located in the at least one intermediate layer. The signal lines are located in the top layer or the bottom layer. The signal gold finger is located in the same board layer as the signal line, is arranged at one end of the signal line and is electrically connected to the signal line. The ground wire and the signal wire are located in the same board layer, disposed on at least one side of the signal wire, and electrically connected to the ground layer through a ground via hole. The grounding gold finger is located in the same board layer as the signal line, is disposed at one end of the grounding line and is electrically connected to the grounding line, and is disposed adjacent to the signal gold finger. The projection of the reflow hole on the at least one intermediate layer is located in the projection area of the grounding gold finger on the at least one intermediate layer, and one end of the reflow hole is connected to the grounding gold finger but does not pass through the grounding gold finger. The grounding gold finger, the other end of the return hole penetrates through one or more intermediate layers of the at least one intermediate layer and is electrically connected to the grounding layer.

Description of drawings

In order to illustrate the technical solutions in the present disclosure more clearly, the following will briefly introduce the accompanying drawings used in some embodiments of the present disclosure. Apparently, the accompanying drawings in the following description are only appendices to some embodiments of the present disclosure. Figures, for those of ordinary skill in the art, other drawings can also be obtained based on these drawings. In addition, the drawings in the following description can be regarded as schematic diagrams, and are not limitations on the actual size of the product involved in the embodiments of the present disclosure, the actual process of the method, the actual timing of signals, and the like.

Figure 1 is a connection diagram of an optical communication system according to some embodiments;

Fig. 2 is a structural diagram of an optical network terminal according to some embodiments;

Fig. 3A is a structural diagram of an optical module according to some embodiments;

Fig. 3B is a structural diagram of another optical module according to some embodiments;

FIG. 4A is an exploded structure diagram of the optical module shown in FIG. 3A;

FIG. 4B is an exploded structure diagram of the optical module shown in FIG. 3B;

5 is a structural diagram of a circuit board according to some embodiments;

FIG. 6 is a structural diagram of an upper surface of a circuit board according to some embodiments;

7 is a cross-sectional structure diagram of a circuit board according to some embodiments;

Fig. 8 is a structural diagram of the part inside the dashed box in Fig. 6;

Fig. 9 is a sectional structure diagram of the circuit board in Fig. 8 along the line A-A;

Fig. 10 is another kind of cross-sectional structural view of the circuit board in Fig. 8 along the A-A line;

Fig. 11 is a cross-sectional structure diagram of an optical module according to some embodiments;

Fig. 12 is a structural diagram of a light emitting device and a light receiving device connected to a circuit board according to some embodiments;

13 is a structural diagram of a first side of a first flexible circuit board according to some embodiments;

14 is a structural diagram of a second side of a first flexible circuit board according to some embodiments;

Figure 15 is a partial enlarged view at E in Figure 13;

Figure 16 is a partial enlarged view at F in Figure 14;

Figure 17 is an exploded structural view of an optical module and a flexible circuit board according to some embodiments;

FIG. 18 is a block diagram of a circuit board according to some embodiments.

detailed description

The technical solutions in some embodiments of the present disclosure will be clearly and completely described below in conjunction with the accompanying drawings. Apparently, the described embodiments are only some of the embodiments of the present disclosure, not all of them. All other embodiments obtained by persons of ordinary skill in the art based on the embodiments provided in the present disclosure belong to the protection scope of the present disclosure.

Throughout the specification and claims, unless the context requires otherwise, the term "comprise" and other forms such as the third person singular "comprises" and the present participle "comprising" are used Interpreted as the meaning of openness and inclusion, that is, "including, but not limited to". In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiments", "example", "specific examples" example)" or "some examples (some examples)" etc. are intended to indicate that specific features, structures, materials or characteristics related to the embodiment or examples are included in at least one embodiment or example of the present disclosure. Schematic representations of the above terms are not necessarily referring to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be included in any suitable manner in any one or more embodiments or examples.

Hereinafter, the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly specifying the quantity of indicated technical features. Thus, a feature defined as "first" and "second" may explicitly or implicitly include one or more of these features. In the description of the embodiments of the present disclosure, unless otherwise specified, "plurality" means two or more.

In describing some embodiments, the expressions "coupled" and "connected" and their derivatives may be used. For example, the term "connected" may be used in describing some embodiments to indicate that two or more elements are in direct physical or electrical contact with each other. As another example, the term "coupled" may be used when describing some embodiments to indicate that two or more elements are in direct physical or electrical contact. However, the terms "coupled" or "communicatively coupled" may also mean that two or more components are not in direct contact with each other, but yet still co-operate or interact with each other. The embodiments disclosed herein are not necessarily limited by the context herein.

"At least one of A, B and C" has the same meaning as "at least one of A, B or C" and both include the following combinations of A, B and C: A only, B only, C only, A and B A combination of A and C, a combination of B and C, and a combination of A, B and C.

"A and/or B" includes the following three combinations: A only, B only, and a combination of A and B.

The use of "suitable for" or "configured to" herein means open and inclusive language that does not exclude devices that are suitable for or configured to perform additional tasks or steps.

Additionally, the use of "based on" is meant to be open and inclusive, as a process, step, calculation, or other action that is "based on" one or more stated conditions or values may in practice be based on additional conditions or beyond stated values.

As used herein, "about", "approximately" or "approximately" includes the stated value as well as the average within the acceptable deviation range of the specified value, wherein the acceptable deviation range is as determined by one of ordinary skill in the art. Determined taking into account the measurement in question and the errors associated with the measurement of a particular quantity (ie, limitations of the measurement system).

In optical communication technology, optical signals are used to carry information to be transmitted, and the optical signals carrying information are transmitted to information processing equipment such as computers through optical fibers or optical waveguides and other information transmission equipment to complete information transmission. Due to the passive transmission characteristics of optical signals when they are transmitted through optical fibers or optical waveguides, low-cost, low-loss information transmission can be achieved. In addition, the signals transmitted by information transmission equipment such as optical fibers or optical waveguides are optical signals, while the signals that can be recognized and processed by information processing equipment such as computers are electrical signals. To establish an information connection between devices, it is necessary to realize the mutual conversion between electrical signals and optical signals. Common information processing equipment includes routers, switches, and electronic computers.

The optical module realizes the mutual conversion function of the above-mentioned optical signal and electrical signal in the technical field of optical fiber communication. The optical module includes an optical port and an electrical port. The optical module realizes optical communication with information transmission equipment such as optical fiber or optical waveguide through the optical port, and realizes the electrical connection with the optical network terminal (such as an optical modem) through the electrical port. Mainly used for power supply, two-wire synchronous serial (Inter-Integrated Circuit, I2C) signal transmission, data signal transmission and grounding, etc.; optical network terminals transmit electrical signals to computers through network cables or wireless fidelity technology (Wi-Fi), etc. information processing equipment.

Fig. 1 is a connection diagram of an optical communication system according to some embodiments. As shown in FIG. 1 , the optical communication system includes a remote server 1000 , a local information processing device 2000 , an optical network terminal 100 , an optical module 200 , an optical fiber 101 and a network cable 103 .

One end of the optical fiber 101 is connected to the remote server 1000 , and the other end is connected to the optical network terminal 100 through the optical module 200 . Optical fiber itself can support long-distance signal transmission, such as signal transmission of several kilometers (6 kilometers to 8 kilometers). On this basis, if repeaters are used, theoretically unlimited distance transmission can be achieved. Therefore, in a common optical communication system, the distance between the remote server 1000 and the optical network terminal 100 can usually reach thousands of kilometers, tens of kilometers or hundreds of kilometers.

One end of the network cable 103 is connected to the local information processing device 2000 , and the other end is connected to the optical network terminal 100 . The local information processing device 2000 may be any one or more of the following devices: routers, switches, computers, mobile phones, tablet computers, televisions, and so on.

The physical distance between the remote server 1000 and the optical network terminal 100 is greater than the physical distance between the local information processing device 2000 and the optical network terminal 100 . The connection between the local information processing device 2000 and the remote server 1000 is completed by 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 module 200 and the optical network terminal 100 .

The optical network terminal 100 includes a substantially rectangular parallelepiped housing (housing), and an optical module interface 102 and a network cable interface 104 disposed on the housing. The optical module interface 102 is configured to be connected to the optical module 200 , so that the optical network terminal 100 establishes a bidirectional electrical signal connection with the optical module 200 . The network cable interface 104 is configured to access the network cable 103, so that the optical network terminal 100 establishes a bidirectional electrical signal connection with the network cable. A connection is established between the optical module 200 and the network cable 103 through the optical network terminal 100 . For example, the optical network terminal 100 transmits the electrical signal from the optical module 200 to the network cable 103, and transmits the electrical signal from the network cable 103 to the optical module 200, so the optical network terminal 100, as the host computer of the optical module 200, can monitor the optical module 200 jobs. In addition to the optical network terminal 100, the host computer of the optical module 200 may also include an optical line terminal (Optical Line Terminal, OLT) and the like.

The optical module 200 includes an electrical port and an optical port. The optical port is configured to be connected to the optical fiber 101, so that the optical module 200 establishes a bidirectional optical signal connection with the optical fiber 101; electrical signal connection. The optical module 200 implements mutual conversion between optical signals and electrical signals, so that a connection is established between the optical fiber 101 and the optical network terminal 100 . For example, the optical signal from the optical fiber 101 is converted into an electrical signal by the optical module 200 and then input into the optical network terminal 100 , and the electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module 200 and input into the optical fiber 101 . Since the optical module 200 is a tool for realizing mutual conversion of photoelectric signals and does not have the function of processing data, the information does not change during the above photoelectric conversion process.

The remote server 1000 establishes a two-way signal transmission channel with the local information processing device 2000 through the optical fiber 101 , the optical module 200 , the optical network terminal 100 and the network cable 103 .

Fig. 2 is a structural diagram of an optical network terminal according to some embodiments. In order to clearly show the connection relationship between the optical module 200 and the optical network terminal 100 , FIG. 2 only shows the structure of the optical network terminal 100 related to the optical module 200 . As shown in Figure 2, the optical network terminal 100 also includes a circuit board 105 arranged in the casing, a cage 106 arranged on the surface of the circuit board 105, a radiator 107 arranged on the cage 106, and an electrical connection arranged in the cage 106 device. The electrical connector is configured to be connected to the electrical port of the optical module 200; the heat sink 107 has a protruding structure such as a fin that increases the heat dissipation area.

The optical module 200 is inserted into the cage 106 of the optical network terminal 100 , and the optical module 200 is fixed by the cage 106 . The heat generated by the optical module 200 is conducted to the cage 106 and then diffused through the radiator 107 . After the optical module 200 is inserted into the cage 106 , the electrical port of the optical module 200 is connected to the electrical connector in the cage 106 , so that the optical module 200 establishes a bidirectional electrical signal connection with the optical network terminal 100 . In addition, the optical port of the optical module 200 is connected to the optical fiber 101 , so that the optical module 200 establishes a bidirectional optical signal connection with the optical fiber 101 .

Fig. 3A is a structural diagram of an optical module according to some embodiments, and Fig. 4A is an exploded structural diagram of the optical module shown in Fig. 3A. As shown in FIG. 3A and FIG. 4A , the optical module 200 includes a shell, a circuit board 300 and a light emitting device 400 disposed in the shell. Fig. 3B is a structural diagram of another optical module according to some embodiments, and Fig. 4B is an exploded structural diagram of the optical module shown in Fig. 3B. As shown in FIG. 3B and FIG. 4B , the optical module 200 includes a shell, a circuit board 300 disposed in the shell, a light emitting device 400 and a light receiving device 500 . When the optical module 200 includes the light emitting device 400 but does not include the light receiving device 500, the optical module can be referred to as an optical transmitting module; It may be called an optical receiving module; when the optical module 200 includes both the light emitting device 400 and the light receiving device 500, the optical module may be called an optical transceiver module.

The casing includes an upper casing 201 and a lower casing 202. The upper casing 201 is covered on the lower casing 202 to form the above-mentioned casing with two openings; the outer contour of the casing generally presents a square shape.

In some embodiments, the lower case 202 includes a bottom plate 2021 and two lower side plates 2022 located on both sides of the bottom plate 2021 and perpendicular to the bottom plate 2021; the upper case 201 includes a cover plate 2011, and the cover plate 2011 covers the lower case 202 on the two lower side panels 2022 to form the above-mentioned housing.

In some embodiments, the lower case 202 includes a bottom plate 2021 and two lower side plates 2022 located on both sides of the bottom plate 2021 and perpendicular to the bottom plate 2021; The two upper side plates perpendicular to the cover plate 2011 are combined with the two lower side plates 2022 to cover the upper case 201 on the lower case 202 .

The direction of the line connecting the two openings 204 and 205 may be consistent with the length direction of the optical module 200 , or may not be consistent with the length direction of the optical module 200 . For example, the opening 204 is located at the end of the optical module 200 (the right end in FIGS. 3A and 3B ), and the opening 205 is also located at the end of the optical module 200 (the left end in FIGS. 3A and 3B ). Alternatively, the opening 204 is located at the end of the optical module 200 , while the opening 205 is located at the side of the optical module 200 . The opening 204 is an electrical port, and the golden finger 310 of the circuit board 300 protrudes from the electrical port 204, and is inserted into a host computer (for example, an optical network terminal 100); the opening 205 is an optical port, which is configured to be connected to an external optical fiber 101 to The optical fiber 101 is connected to the light emitting device 400 and the light receiving device 500 in the optical module 200 .

The assembly method of combining the upper housing 201 and the lower housing 202 is used to facilitate the installation of optical devices such as the circuit board 300, the light emitting device 400, and the light receiving device 500 into the above housing, and the upper housing 201 and the lower housing 202 Form package protection for these devices. In addition, when assembling components such as the circuit board 300 , the light emitting device 400 and the light receiving device 500 , it facilitates the deployment of positioning components, heat dissipation components, and electromagnetic shielding components of these components, which is conducive to automatic production.

In some embodiments, the upper housing 201 and the lower housing 202 are made of metal materials, which is beneficial to realize electromagnetic shielding and heat dissipation.

In some embodiments, the optical module 200 further includes an unlocking component 203 located outside its housing. The unlocking component 203 is configured to realize the fixed connection between the optical module 200 and the upper computer, or release the fixed connection between the optical module 200 and the upper computer.

For example, the unlocking part 203 is located on the outer side of the two lower side plates 2022 of the lower housing 202, and has an engaging part that matches the cage 106 of the upper computer; The locking part fixes the optical module 200 in the cage 106; when the unlocking part 203 is pulled, the locking part of the unlocking part 203 moves accordingly, thereby changing the connection relationship between the locking part and the upper computer, so as to release the connection between the optical module 200 and the upper computer. engagement relationship, so that the optical module 200 can be pulled out from the cage 106 .

The circuit board 300 includes circuit traces, electronic components and chips, etc. The electronic components and chips are connected together according to the circuit design through the circuit traces, so as to realize functions such as power supply, electrical signal transmission and grounding. The electronic components may include, for example, capacitors, resistors, transistors, and metal-oxide-semiconductor field-effect transistors (Metal-Oxide-Semiconductor Field-Effect Transistor, MOSFET). The chip can include, for example, a Microcontroller Unit (MCU), a laser driver chip, a limiting amplifier (Limiting Amplifier), a clock data recovery chip (Clock and Data Recovery, CDR), a power management chip, a digital signal processing (Digital Signal Processing , DSP) chip.

In some embodiments, the aforementioned chip is an integrated chip capable of realizing at least two functions. For example, a laser driver chip and an MCU are integrated into an integrated chip, or a laser driver chip, an MCU and a limiting amplifier are integrated into an integrated chip. A chip is an integration of circuits. In the aforementioned integrated chip, the functions of each circuit have not disappeared due to integration, but the appearance has changed. The integrated chip still has the function of the original circuit. Therefore, the circuit board 300 includes the technical scheme of an integrated chip that integrates the functions of the laser driver chip, the MCU and the limiting amplifier, which is different from the technology in which the circuit board 300 includes three independent chips of the independent laser driver chip, the MCU and the limiting amplifier. Compared with the scheme, the functions and functions are the same.

The circuit board 300 is generally a rigid circuit board. Due to its relatively hard material, the rigid circuit board can also realize the bearing function, such as the rigid circuit board can stably carry the above-mentioned electronic components and chips; the rigid circuit board can also be inserted into the cage 106 of the host computer in the electrical connector.

The circuit board 300 also includes a gold finger 310 formed on the surface of its end, and the gold finger 310 is composed of a plurality of independent pins. The circuit board 300 is inserted into the cage 106 , and is conductively connected with the electrical connector in the cage 106 by the golden finger 310 . The gold finger 310 can be arranged only on the surface of one side of the circuit board 300 (for example, the upper surface shown in FIG. 4A and FIG. 4B ), and can also be arranged on the surface of the upper and lower sides of the circuit board 300, so as to adapt to the occasion where the number of pins is large. . The gold finger 310 is configured to establish an electrical connection with the host computer to realize power supply, grounding, I2C signal transmission, data signal transmission and the like.

Of course, some optical modules 200 also use flexible circuit boards. Flexible circuit boards are generally used in conjunction with rigid circuit boards as a supplement to rigid circuit boards.

The light emitting device 400 is configured to realize the transmission of light signals, and the light receiving device is configured to realize the reception of light signals.

The light emitting device 400 generally includes a laser, a lens, and a photodetector, and the lens and the photodetector are respectively located on two opposite sides of the laser. For example, the lens is located on the light emitting side of the laser, and the photodetector is located on the backlight side of the laser. The light emitting side and the backlight side of the laser respectively emit light beams, and the intensity of the light beam emitted from the light emitting side of the laser is greater than the intensity of the light beam emitted from the backlight side of the laser. For example, the intensity of the beam emitted from the light emitting side of the laser accounts for 95% of the total intensity of the beam emitted by the laser, while the intensity of the beam emitted from the backlight side of the laser accounts for 5% of the total intensity of the beam emitted by the laser. The lens is configured to converge the light beam emitted from the light output side of the laser into converged light, so as to facilitate the coupling of the converged light to the external optical fiber 101 . The light detector is configured to receive the light beam emitted from the backlight side of the laser to detect the optical power of the laser, so as to ensure the stability of the optical power of the laser.

FIG. 5 is a structural diagram of a circuit board according to some embodiments. Fig. 6 is a structural diagram of the upper surface of a circuit board according to some embodiments, and no electronic components are connected to the circuit board in Fig. 6 . As shown in Figures 5 and 6, the circuit board 300 includes a plurality of functional chips 600 formed on its surface (such as the aforementioned MCU, laser driver chip, limiting amplifier, CDR, power management chip, DSP, etc.) The golden finger 310 on one end of the surface connects multiple functional chips 600 in the optical module 200 according to the circuit design through circuit wiring, so as to realize electrical functions such as power supply, electrical signal transmission, and grounding.

The circuit traces of the circuit board 300 include signal wires and ground wires. A plurality of functional chips 600 are connected to the gold fingers 310 through signal lines. Signal crosstalk easily occurs between two adjacent signal lines, thereby affecting the performance of the optical module 200 . The ground line is located on the adjacent side of the signal line to form a signal return path, thereby reducing signal crosstalk.

In order to realize functions such as power supply, electrical signal transmission, and grounding for multiple functional chips 600, the circuit board 300 has a multi-layer structure, and each layer includes different circuit traces, and then through The via hole guides the signal to the position of the gold finger 310 on the top layer, and then connects to the outside (for example, the optical network terminal 100 ) through the gold finger 310 . The signal lines in the circuit board 300 include high-speed signal lines and low-speed signal lines. The high-speed signal lines are, for example, differential signal lines, and the low-speed signal lines are, for example, power lines. Exemplarily, high-speed signal lines are disposed in the top and bottom layers of the circuit board 300 , while low-speed signal lines are disposed in the middle board layer of the circuit board 300 .

The gold finger 310 generally includes a signal gold finger and a ground gold finger, the signal gold finger is connected to the signal line, and the ground gold finger is connected to the ground line. In order to form a signal return path, the ground gold fingers are arranged on both sides of the signal gold fingers, and one end of the ground wire connected to the ground gold fingers is connected to the ground layer of the circuit board 300 through the ground via hole in the circuit board 300 . However, due to this signal return path, the signal return of the ground gold finger can only reach the ground via hole of the ground wire, and then be connected to the ground plane through the ground via hole. The signal return path is less, and the signal return path is longer, which is easy to cause loss.

In order to solve the above problems, some embodiments of the present disclosure provide a circuit board 300 , which includes a signal line 320 , a signal gold finger 311 , a ground line 330 and a ground gold finger 312 . The signal line 320 is arranged on the top layer of the circuit board 300 , and the signal golden finger 311 is arranged at one end of the signal line 320 and is configured to be connected to a host computer. The ground wire 330 is disposed on at least one side of the signal wire 320 , and one end of the ground wire 330 is connected to the ground gold finger 312 , and the ground gold finger 312 is disposed adjacent to the signal gold finger 311 . The circuit board 300 includes a plurality of buried holes, one end of which is connected to the grounding gold finger 312 but does not penetrate through the grounding gold finger 312 , and the other end of the buried hole is connected to the ground layer in the circuit board 300 . The signal return path of the signal gold finger 311 is increased from the original single and longer return path, that is, through the ground gold finger 312 to the ground via hole 3001 of the ground wire 330, and then returns to the ground layer 3002 through the ground via hole 3001, which is increased to two There are two return paths, one for returning to the ground layer 3002 through the grounding gold finger 312, and the other for returning to the buried hole through the grounding gold finger 312, and then returning to the grounding layer 3002 through the buried hole. The number of signal return paths of the signal golden finger 311 is increased and the length of the signal return paths is shortened, which is beneficial to reduce loss and increase signal frequency.

Fig. 7 is a cross-sectional structure diagram of a circuit board according to some embodiments. As shown in FIGS. 6 and 7 , the circuit board 300 includes a first ply 301 , a second ply 302 , a third ply 303 , a fourth ply 304 , a fifth ply 305 , and a sixth ply stacked in sequence. 306 , the seventh board layer 307 and the eighth board layer 308 , a dielectric layer is filled between every two adjacent board layers, and the dielectric layer is made of insulating material. Exemplarily, the medium layer may use glass fiber or epoxy resin. Each layer of the circuit board 300 is made of copper.

In some embodiments, the outermost layers of the circuit board 300 are called the top layer and the bottom layer, respectively, and the other layers are called the middle layer 309 . That is, the top layer in FIG. 7 is the first ply 301, the bottom layer is the eighth ply 308, and the middle layer 309 includes the second ply 302, the third ply 303, the fourth ply 304, the fifth ply 305, The sixth ply 306 and the seventh ply 307 . One or several board layers in the middle layer 309 include the ground layer 3002 .

FIG. 8 is a structural diagram of the part inside the dashed box in FIG. 6 . As shown in FIG. 8 , the first board layer 301 includes signal wires 320 (eg, differential signal wires), ground wires 330 , signal gold fingers 311 (eg, differential signal gold fingers) and ground gold fingers 312 . Exemplarily, when the signal line 320 is a differential signal line 320 , the differential signal line 320 includes a positive differential signal line 321 and a negative differential signal line 322 . The ground line 330 includes a first sub-ground line 331 and a second sub-ground line 332 . The first sub-ground line 331 and the second sub-ground line 332 are respectively disposed on two sides of the positive differential signal line 321 and the negative differential signal line 322 . The ground gold finger 312 includes a first sub-ground gold finger 3121 and a second sub-ground gold finger 3122 . When the signal gold finger 311 is a differential signal gold finger 311 , the differential signal gold finger 311 includes a positive differential signal gold finger 3111 and a negative differential signal gold finger 3112 . One end of the first sub-ground wire 331 is connected to the first sub-ground gold finger 3121, one end of the second sub-ground wire 332 is connected to the second sub-ground gold finger 3122, one end of the positive differential signal line 321 is connected to the positive differential signal gold finger 3111, and the negative One end of the differential signal line 322 is connected to the negative differential signal golden finger 3112 . The positive differential signal gold finger 3111 and the negative differential signal gold finger 3112 are disposed between the first sub-ground gold finger 3121 and the second sub-ground gold finger 3122 . The positive differential signal gold finger 3111 is disposed between the first sub-ground gold finger 3121 and the negative differential signal gold finger 3112 , and the negative differential signal gold finger 3112 is disposed between the positive differential signal gold finger 3111 and the second sub-ground gold finger 3122 .

In order to facilitate the connection between the gold finger 310 and the host computer, the gold finger 310 is located at the end of the circuit board 300. For the convenience of expression, the end of the circuit board 300 where the gold finger 310 is located is referred to as the end in this disclosure. The other end is called the origin.

Usually, the distance between the end of the positive differential signal gold finger 3111 and the end of the negative differential signal gold finger 3112 to the end face of the circuit board 300 is greater than the distance between the end of the first sub-ground gold finger 3121 and the end of the second sub-ground gold finger 3122. The distance between the end face of the circuit board 300 and the grounding gold finger 312 form a semi-enclosed structure with the positive differential signal gold finger 3111 and the negative differential signal gold finger 3112, which is beneficial to shorten the signal return path and reduce loss.

The circuit board 300 also includes a plurality of buried holes, and the plurality of buried holes are located under the first sub-ground gold finger 3121 . Different board layers in the circuit board 300 are usually used to realize different circuit connections, and then realize the circuit of each board layer in the middle layer 309 and the golden finger 310 of the first board layer 301 through the buried hole between the board layers. the connection between.

In order to increase the signal return path of the positive differential signal gold finger 3111, in some embodiments, the circuit board 300 further includes a first return hole group 340, and the first return hole group 340 is located on the first sub-ground gold finger 3121 on the middle layer 309 within the projection area. One end of the first return hole group 340 is connected to the first sub-ground gold finger 3121 , and the other end is connected to the ground layer 3002 of the middle layer 309 , and is configured to connect the first sub-ground gold finger 3121 and the ground wire 330 of the middle layer 309 .

The return path of the signal of the positive differential signal gold finger 3111 is changed from the original single return path, that is, to the ground layer through the first sub-ground gold finger 3121, to two return paths, which are respectively the return flow through the first sub-ground gold finger 3121 to the ground layer, and to the ground layer through the first sub-ground gold finger 3121 to the first return hole group 340 . In this way, the latter increases the signal return path and reduces losses.

One end of the first return hole group 340 is connected to the first sub-ground gold finger 3121, and the other end is connected to the ground layer 3002 of the intermediate layer 309, that is, the other end of the first return hole group 340 can be connected to the second board layer 302, the third The grounding layer 3002 of one or several of the board layers 303 , the fourth board layer 304 , the fifth board layer 305 , the sixth board layer 306 and the seventh board layer 307 is connected. Exemplarily, if the other end of the first return hole group 340 is connected to the ground layer 3002 of the third board layer 303 , the first return hole group 340 runs through the board layer between the top layer and the third board layer 303 . Alternatively, if the other end of the first return hole group 340 is connected to the ground layer 3002 of the fourth board layer 304 , the first return hole group 340 runs through the board layer between the top layer and the fourth board layer 304 .

FIG. 9 is a cross-sectional structure diagram of the circuit board in FIG. 8 along line A-A. As shown in FIG. 9, in some embodiments, the other end of the first return hole group 340 is connected to the ground layer 3002 of the third board layer 303, and the first return hole group 340 runs through the gap between the top layer and the third board layer 303. ply. The return path of the signal of the positive differential signal gold finger 3111 includes two paths, one is to return to the ground layer 3002 through the first sub-ground gold finger 3121 and the ground via hole 3001 on the top layer, and the other is to pass through the first sub-ground gold finger on the top layer 3121 to the first return hole group 340, and then flow back to the ground layer 3002 through the first return hole group 340. In this way, the number of signal return paths is increased, the length of the signal return paths is reduced, and the loss is reduced.

In some embodiments, one end of the first return hole group 340 is connected to the first sub-ground gold finger 3121 , and the other end may be connected to the ground layer 3002 of the second board layer 302 . FIG. 10 is another cross-sectional structure diagram of the circuit board in FIG. 8 along line A-A. As shown in Figure 10, the return path of the signal of the positive differential signal gold finger 3111 includes two paths, one is to return to the ground layer 3002 through the first sub-ground gold finger 3121 and the ground via hole 3001 on the top layer, and the other is to flow back to the ground layer 3002 through the top layer The first sub-ground gold finger 3121 flows to the first return hole set 340 , and then flows back to the ground layer 3002 through the first return hole set 340 . In this way, the number of signal return paths is increased, the length of the signal return paths is reduced, and the loss is reduced.

The projection of the first return hole group 340 on the middle layer 309 overlaps with the ground layer 3002 of the middle layer 309, and the number of return holes in the first return hole group 340 can be based on the overall length of the first sub-ground gold finger 3121 and the single return hole to set the diameter. Exemplarily, the number of return holes in the first return hole group 340 may be 1 to 8, for example, 1, 2, 3, 4, 5, 6, 7 or 8.

As shown in FIG. 8 , in some embodiments, the first return hole group 340 includes five return holes, which are called first according to the distance between each return hole and the end of the first sub-ground gold finger 3121 from small to large. The backflow hole 341 , the second backflow hole 342 , the third backflow hole 343 , the fourth backflow hole 344 and the fifth backflow hole 345 .

In some embodiments, the first return holes 341 , the second return holes 342 , the third return holes 343 , the fourth return holes 344 and the fifth return holes 345 may be equally spaced on the first sub-ground gold finger 3121 , or Can be distributed unevenly. The distance between the return holes is the distance between the central axes of the adjacent return holes.

In order to facilitate the preparation and improve the yield of the finished product, usually the first return hole 341, the second return hole 342, the third return hole 343, the fourth return hole 344 and the fifth return hole 345 are equally spaced on the first sub-ground gold finger 3121 Distribution, and the first return hole 341 and the second return hole 342, the second return hole 342 and the third return hole 343, the third return hole 343 and the fourth return hole 344, the fourth return hole 344 and the fifth return hole 345 The distance between them is equal to the distance from the first return hole 341 to the end of the first sub-ground gold finger 3121, and the distance from the fifth return hole 345 to the beginning of the first sub-ground gold finger 3121, which makes the circuit board 300 more convenient to prepare, and makes The appearance of the circuit board 300 is more beautiful.

Usually, the diameter of a single return hole should be smaller than the width of the first sub-ground gold finger 3121 , and the projection of the first sub-ground gold finger 3121 on the middle layer 309 completely covers each return hole. For high-speed signals, the smaller the diameter of a single reflow hole, the better, but in consideration of the actual processing capacity, the diameter of a single reflow hole is generally 3mil-8mil (mil, 1mil=0.001 inch=0.0254mm). Exemplarily, the diameter of the return hole can be 3mil, 4mil, 5mil, 6mil, 7mil, 8mil. In some embodiments, the surface of the inner wall of each reflow hole is covered with a metal layer configured to enhance signal reflow.

In some embodiments, each reflow hole is a buried hole, that is, each reflow hole does not penetrate the gold finger of the top layer, nor does it penetrate the ground layer 3002 of the board layer farthest from the top layer connected to it in the middle layer 309 .

In order to increase the signal return path of the negative differential signal gold finger 3112, in some embodiments, the circuit board 300 further includes a second return hole group 350, and the second return hole group 350 is located on the middle layer 309 of the second sub-ground gold finger 3122 within the projection area. One end of the second return hole group 350 is connected to the second sub-ground gold finger 3122 , and the other end is connected to the ground layer 3002 of the middle layer 309 , and is configured to connect the second sub-ground gold finger 3122 and the ground layer 3002 .

The signal return path of the negative differential signal gold finger 3112 is changed from the original single return path, that is, to the ground layer 3002 through the second sub-ground gold finger 3122 and the ground via hole 3001, to two return paths, respectively through the second sub- The ground gold finger 3122 and the ground via hole 3001 return to the ground layer 3002 , and flow back to the ground layer 3002 through the second sub-ground gold finger 3122 to the second return hole group 350 . In this way, the number of signal return paths is increased, the length of the signal return paths is reduced, and the loss is reduced.

The setting of the second return hole group 350 between different board layers can refer to the first return hole group 340. One end of the second return hole group 350 is connected to the second sub-ground gold finger 3122, and the other end is connected to the ground layer of the middle layer 309. 3002 connection, that is, the other end of the second return hole group 350 can be connected to the second layer 302, the third layer 303, the fourth layer 304, the fifth layer 305, the sixth layer 306 and the seventh layer 307 The ground layer 3002 of a certain layer or several layers of the species is connected. Exemplarily, if the other end of the second return hole group 350 is connected to the ground layer 3002 of the third board layer 303 , the second return hole group 350 runs through the board layer between the top layer and the third board layer 303 . Alternatively, if the other end of the second return hole group 350 is connected to the ground layer 3002 of the fourth board layer 304 , the second return hole group 350 runs through the board layer between the top layer and the fourth board layer 304 .

The projection of the second return hole group 350 on the middle layer 309 overlaps with the ground layer 3002 of the middle layer 309, and the number of return holes in the second return hole group 350 can be based on the overall length of the second sub-ground gold finger 3122 and the single return hole to set the diameter. Exemplarily, the number of return holes in the second return hole group 350 may be 1 to 8, for example, 1, 2, 3, 4, 5, 6, 7 or 8.

In some embodiments, the second return hole group 350 includes five return holes, which are called the sixth return hole 351, the seventh return hole in sequence according to the distance between each return hole and the end of the second sub-ground gold finger 3122 from small to large. The return hole 352 , the eighth return hole 353 , the ninth return hole 354 and the tenth return hole 355 .

In some embodiments, the sixth return holes 351 , the seventh return holes 352 , the eighth return holes 353 , the ninth return holes 354 and the tenth return holes 355 may be equally spaced on the second sub-ground gold finger 3122 , or Can be distributed in non-divided intervals. The distance between the return holes is the distance between the central axes of the adjacent return holes.

In order to facilitate the preparation and improve the yield of finished products, for example, the sixth reflow hole 351, the seventh reflow hole 352, the eighth reflow hole 353, the ninth reflow hole 354 and the tenth reflow hole 355 are connected to the second sub-ground gold finger 3122. The top is equally spaced, and the sixth return hole 351 and the seventh return hole 352, the seventh return hole 352 and the eighth return hole 353, the eighth return hole 353 and the ninth return hole 354, the ninth return hole 354 and the tenth return hole The distance between the reflow holes 355 is equal to the distance from the sixth reflow hole 351 to the end of the second sub-ground gold finger 3122, and the distance from the tenth reflow hole 355 to the beginning of the second sub-ground gold finger 3122, making the circuit board 300 more convenient to prepare , and make the appearance of the circuit board 300 more beautiful.

If the signal line 320, the ground line 330, the signal gold finger 311, and the ground gold finger 312 on the top layer are respectively called the top layer signal line, the top layer ground wire, the top layer signal gold finger, and the top layer ground gold finger, then similarly, the circuit board 300 It also includes bottom signal wires (for example, high-speed signal wires), bottom ground wires, bottom signal gold fingers, and bottom ground gold fingers on the bottom layer. The bottom ground gold finger is set close to the bottom signal gold finger. The circuit board 300 also includes a bottom layer return hole group to correspond to the bottom layer signal golden fingers disposed on the bottom layer, so as to increase the number of signal return paths or reduce the length of the signal return paths. The arrangement of the bottom return hole group refers to the arrangement of the first return hole group 340 and the second return hole group 350 . The projection of the bottom ground gold finger on the middle layer 309 covers the bottom return hole group, and one end of the bottom return empty group is connected to the bottom ground gold finger, and the other end is connected to the ground layer 3002 of the middle layer 309 .

As shown in FIG. 4B , the light-emitting device 400 and the light-receiving device 500 are located on the edge of the circuit board 300 , and the light-emitting device 400 and the light-receiving device 500 are stacked one above the other. Exemplarily, the light emitting device 400 is closer to the upper case 201 than the light receiving device 500 , but not limited thereto, and the light receiving device 500 may be closer to the upper case 201 than the light emitting device 400 . When the light-emitting device 400 is closer to the upper housing 201 than the light-receiving device 500 , the light-emitting device 400 and the light-receiving device 500 are disposed in the enclosure cavity formed by the upper housing 201 and the lower housing 202 . The lower case 202 can support the light receiving device 500 ; for example, the lower case 202 supports the light receiving device 500 through spacers, and the light receiving device 500 supports the light emitting device 400 .

In other embodiments, the light-emitting device 400 and the light-receiving device 500 may also be an integrated transceiver structure. Exemplarily, the light emitting device 400 and the light receiving device 500 are located at the end of the circuit board 300 and connected to the circuit board 300 through a flexible circuit board. The light emitting device 400 and the light receiving device 500 can be connected to the circuit board 300 through one flexible circuit board, or can be connected to the circuit board 300 through multiple flexible circuit boards.

In some embodiments, the light emitting device 400 and the light receiving device 500 are physically separated from the circuit board 300 respectively, and are connected to the circuit board 300 through a flexible circuit board or an electrical connector.

The crosstalk between signals not only exists in the circuit traces of the circuit board 300, but also exists between the signal lines of the flexible circuit board.

FIG. 11 is a cross-sectional structure diagram of an optical module according to some embodiments. As shown in FIG. 11 , the light emitting device 400 and the light receiving device 500 are electrically connected to the circuit board 300 through a plurality of flexible circuit boards. The plurality of flexible circuit boards includes a first flexible circuit board 360 , a second flexible circuit board 370 and a third flexible circuit board 380 . The light emitting device 400 is connected to the circuit board 300 through the first flexible circuit board 360 and the third flexible circuit board 380, the light receiving device 500 is connected to the circuit board 300 through the second flexible circuit board 370, and the third flexible circuit board 380 is arranged on the second flexible circuit board 380. Between the first flexible circuit board 360 and the second flexible circuit board 370 .

In some embodiments, the first flexible circuit board 360 includes a high-speed signal line configured to transmit high-speed signals between the circuit board 300 and the light-emitting device 400, and the first flexible circuit board 360 transmits high-speed signals to the light-emitting device 400 . The third flexible circuit board 380 includes low-speed signal lines such as power lines, and is configured for the circuit board 300 to supply power to electronic components in the light emitting device 400 . The second flexible circuit board 370 includes high-speed signal lines configured to transmit high-speed current signals converted by the light receiving device 500 to the circuit board 300 , and the light receiving device 500 transmits high-speed signals to the circuit board 300 through the second flexible circuit board 370 . Therefore, separate transmission of high-speed signals between the light emitting device 400 , the light receiving device 500 and the circuit board 300 is realized through the first flexible circuit board 360 and the second flexible circuit board 370 . In addition, the second flexible circuit board 370 may further include some power lines configured to enable the circuit board 300 to supply power to the electronic components in the light receiving device 500 .

In other embodiments, the multiple flexible circuit boards further include a fourth flexible circuit board on which low-speed signal lines such as power lines are laid, and the light-receiving device 500 is connected to the circuit board 300 through the fourth flexible circuit board, and the fourth flexible circuit board Configured for the circuit board 300 to supply power to electronic components within the light receiving device 500 , the fourth flexible circuit board may be disposed between the second flexible circuit board 370 and the third flexible circuit board 380 . In this case, the second flexible circuit board 370 does not need to include a power line.

In the traditional optical module 200, the light-emitting device 400 and the light-receiving device 500 are usually connected to the circuit board 300 by using a flexible circuit board (for ease of description, the flexible circuit board connecting the light-emitting device 400 and the circuit board 300 is called a flexible circuit board. Board 1, the flexible circuit board connecting the light receiving device 500 and the circuit board 300 is referred to as flexible circuit board 2). When the light-emitting device 400 and the light-receiving device 500 are stacked up and down, the distance between the flexible circuit board 1 and the flexible circuit board 2 is relatively short (close to being arranged side by side). Generally, the flexible circuit board includes a two-layer structure, one layer is a high-speed signal line and power line layer, and the other layer is a ground layer. Even if the high-speed signal line and power line corresponding to the light emitting device 400 are laid on the side of the flexible circuit board 1 away from the flexible circuit board 2, and the ground wire is laid on the side of the flexible circuit board 1 close to the flexible circuit board 2, the flexible circuit board 2 The high-speed signal line and the high-speed signal line and power line layer of the flexible circuit board 1 are only separated by the ground layer of the flexible circuit board 1, so it is difficult to achieve a good isolation effect on the radiation generated by the multi-channel high-speed signal line.

In the optical module 200 provided by some embodiments of the present disclosure, the second flexible circuit board 370 is arranged between the first flexible circuit board 360 and the third flexible circuit board 380, and the second flexible circuit board 370 includes at least a power line and The ground wire, so that the radiation crosstalk generated between the high-speed signal lines on the first flexible circuit board 360 and the high-speed signal lines on the second flexible circuit board 370 can be shielded by the third flexible circuit board 380, which helps to reduce the high-speed The bit error rate caused by the radiation crosstalk generated by the signal line to the optical signal transmitted or received by the optical module 200 .

In the traditional optical module 200, when the light-emitting device 400 is only connected to the circuit board 300 through the flexible circuit board 1, if the light-emitting device 400 includes multiple signal paths, such as 4, 8, etc., high-speed signal lines, power lines, etc. The number of wires will reach dozens. If dozens of wires are arranged side by side on the flexible circuit board 1 , a relatively wide flexible circuit board 1 is required, which will lead to tight layout of the circuit board 300 . The optical module 200 provided by some embodiments of the present disclosure shares the layout requirements of the flexible circuit board 1 through the first flexible circuit board 360 and the third flexible circuit board 380, which is beneficial to alleviate the connection line (high speed) connecting the light emitting device 400 and the circuit board 300 The tense layout of the signal line, power line, etc.) promotes the development of more than 200 signal channels of the optical module to a certain extent.

Fig. 12 is a structural diagram of a light emitting device and a light receiving device connected to a circuit board according to some embodiments. As shown in FIG. 12 , the light emitting device 400 is stacked above the light receiving device 500 . One end of the first flexible circuit board 360 is connected to the light emitting device 400 and the other end is connected to the circuit board 300 . One end of the third flexible circuit board 380 is connected to the light emitting device 400 and the other end is connected to the circuit board 300 . That is, the light emitting device 400 is connected to the circuit board 300 through the first flexible circuit board 360 and the third flexible circuit board 380 , and the first flexible circuit board 360 is disposed above the third flexible circuit board 380 . One end of the second flexible circuit board 370 is connected to the light receiving device 500, and the other end is connected to the circuit board 300. The light receiving device 500 is connected to the circuit board 300 through the second flexible circuit board 370, and the second flexible circuit board 370 is arranged on the second flexible circuit board 370. Below the third flexible circuit board 380 , the third flexible circuit board 380 is disposed between the first flexible circuit board 360 and the second flexible circuit board 370 . If the light receiving device 500 is stacked on the light emitting device 400, the second flexible circuit board 370 is arranged above the third flexible circuit board 380, and the first flexible circuit board 360 is arranged below the third flexible circuit board 380, It is realized that the third flexible circuit board 380 is disposed between the first flexible circuit board 360 and the second flexible circuit board 370 .

As shown in FIG. 12 , limited by the size of the optical module 200, the distance between the light emitting device 400, the light receiving device 500 and the circuit board 300 is relatively short, so that the distance between the light emitting device 400, the light receiving device 500 and the circuit board 300 As shown in Figure 11, the flexible circuit board in between has a relatively large curvature. When the rigidity of the flexible circuit board reaches a certain level, if the flexible circuit board encounters a strong bending, it is easy to break. In order to reduce the rigidity of the flexible circuit board and prevent the flexible circuit board from breaking due to strong bending, some embodiments of the present disclosure also provide a new structure of the flexible circuit board. The first flexible circuit board 360 is taken as an example below for illustration.

Fig. 13 is a structural diagram of a first side of a first flexible circuit board according to some embodiments, and Fig. 14 is a structural diagram of a second side of a first flexible circuit board according to some embodiments. As shown in FIGS. 13 and 14 , the first flexible circuit board 360 in some embodiments of the present disclosure includes a first base 361 , a first metal layer 362 located on the first surface of the first base 361 , and a second metal layer 362 located on the second surface of the first base 361 . The second metal layer 363 on the surface. The first metal layer 362 includes at least one high-speed signal line group 3621 and at least one first reference ground 3622, and a first reference ground 3622 is provided on both sides of a high-speed signal line group 3621, thereby separating different high-speed signal line groups 3621 open. The first metal layer also includes at least one first hollowed out area 3623, at least one first hollowed out area 3623 is located in the corresponding first reference ground 3622; no metal is set in the first hollowed out area 3623, that is, the first metal layer 362 The position of the first hollowed out area 3623 is hollowed out. The second metal layer 363 includes at least one second reference ground 3631 and at least one second hollowed out area 3632, at least one second hollowed out area 3632 is located in the corresponding second reference ground 3631; no second hollowed out area 3632 is provided The metal, that is, the second metal layer 363 is hollowed out at the second hollowed out region 3632 . In some embodiments, the first substrate 361 is based on polyimide or polyester film.

By setting the high-speed signal line group 3621, the first reference ground 3622 and the first hollowed out area 3623 on the first metal layer 362, and making the first hollowed out area 3623 located in the first reference ground 3622, the first reference ground is reduced. Ground 3622 to lay metal in the area. Similarly, by setting the second reference ground 3631 and the second hollowed out area 3632 on the second metal layer 363, and making the second hollowed out area 3632 located in the second reference ground 3631, the laying of the second reference ground 3631 is reduced. area of metal. The setting of the first hollowed out area 3623 and the second hollowed out area 3632 reduces the rigidity of the first flexible circuit board 360, so as to prevent the first flexible circuit board 360 from breaking when it encounters strong bending.

In some embodiments, at least one first hollowed out area 3623 and at least one second hollowed out area 3632 are uniformly arranged in at least one first reference ground 3622 and at least one second reference ground 3631 respectively, so as to ensure the first flexible The rigidity of each part of the circuit board 360 is approximately the same. Exemplarily, the first hollowed out area 3623 is set at the middle position of the corresponding first reference ground 3622 , and the second hollowed out area 3632 is set at the middle position of the corresponding second reference ground 3631 . In addition, both sides of at least one high-speed signal line group 3621 are provided with a first reference ground 3622, so the first reference ground 3622 can realize the shielding of high-speed signals between multiple signal channels, thereby reducing adjacent signals (for example, differential signals) The crosstalk among them can avoid affecting the performance of the optical module 200 due to the crosstalk of signals in the multi-signal channels on the flexible circuit board. As shown in FIG. 13 , each high-speed signal wire group 3621 may include a pair of high-speed signal wires or one high-speed signal wire, which can be selected according to actual needs.

FIG. 15 is a partial enlarged view at E in FIG. 13 , and FIG. 16 is a partial enlarged view at F in FIG. 14 . As shown in Figures 15 and 16, in some embodiments, the projection of a second reference ground 3631 on the first substrate 361 covers the projection of the corresponding high-speed signal line group 3621 on the first substrate 361, the high-speed signal line The group 3621 is surrounded by the first reference ground 3622 on both sides and the second reference ground 3631 on the back, which can shield high-speed signals between multiple signal channels and reduce crosstalk between adjacent high-speed signal line groups 3621 . The width of the traces forming each first reference ground 3622 is greater than the width of the traces forming each high-speed signal line group 3621, so that the crosstalk between adjacent high-speed signal line groups 3621 can be further reduced to ensure high-speed signal between multiple signal channels. shielding performance.

As shown in FIG. 15 and FIG. 16 , in some embodiments, the projection of a second reference ground 3631 on the first base 361 covers the projection of the corresponding first reference ground 3622 on the first base 361 . The first flexible circuit board 360 also includes a via hole 364, the via hole 364 is located in the overlapping area of the second reference ground 3631 and the first reference ground 3622, and the corresponding first reference ground 3622 and the second reference ground 3622 are connected through the via hole 364. The reference ground 3631 is used to shield high-speed signals among multiple signal channels on the first flexible circuit board 360 , so as to reduce crosstalk between adjacent high-speed signal line groups 3621 on the first flexible circuit board 360 . In some embodiments, the first flexible circuit board 360 further includes a plurality of via holes 364, and the plurality of via holes 364 are distributed on both sides of at least one first hollowed out area 3623. Exemplarily, the plurality of via holes 364 are uniformly distributed on both sides of at least one first hollowed-out area 3623 .

As shown in FIG. 15 and FIG. 16 , in some embodiments, the projection of a second hollowed out area 3632 on the first base 361 covers the projection of the corresponding first hollowed out area 3623 on the first base 361 . Exemplarily, the projection of the second hollowed out area 3632 on the first base 361 can coincide with the projection of the first hollowed out area 3623 on the first base 361 , so that the rigidity of each part of the first flexible circuit board 360 can be compared uniform, thereby preventing the first flexible circuit 360 from breaking when it encounters strong bending.

In some embodiments, the second flexible circuit board 370 includes a second substrate, a third metal layer disposed on the first surface of the second substrate, and a fourth metal layer disposed on the second surface of the second substrate. The third metal layer includes at least one third reference ground and at least one third hollowed out area, at least one third hollowed out area is located in the corresponding third reference ground; no metal is set in the third hollowed out area, that is, the third metal The layer is hollowed out at the location of the third hollowed out region. The fourth metal layer includes at least one high-speed signal line group and at least one fourth reference ground, and a fourth reference ground is provided on both sides of a high-speed signal line group, so that different high-speed signal lines on the second flexible circuit board 370 Groups are spaced apart. The fourth metal layer also includes at least one fourth hollowed out area, and at least one fourth hollowed out area is located in the corresponding fourth reference ground; no metal is set in the fourth hollowed out area, that is, the fourth metal layer is located in the fourth hollowed out area. Areas are hollowed out. The second flexible circuit board 370 uses the third reference ground to set the third hollowed out area and the fourth reference ground to set the fourth hollowed out area, which reduces the area of laying metal on the second flexible circuit board 370, thereby reducing the second flexible circuit board 370. The rigidity of the circuit board 370 prevents the second flexible circuit board 370 from breaking when subjected to strong bending.

In some embodiments, the projection of a third reference ground on the second substrate covers the projection of the corresponding high-speed signal line group on the second flexible circuit board 370 on the second substrate, and thus the projection on the second flexible circuit board 370 The high-speed signal line group is surrounded by the fourth reference ground on both sides and the third reference ground on its back, which can shield the high-speed signals between multiple signal channels on the second flexible circuit board 370, reducing the distance between adjacent high-speed signal line groups. Crosstalk between.

In some embodiments, a projection of a third reference ground on the second base covers a projection of a corresponding fourth reference ground on the second base. The second flexible circuit board 370 also includes a via hole, which is located in the area where the third reference ground and the fourth reference ground overlap, and the corresponding third reference ground and the fourth reference ground are connected through the via hole to perform the first The shielding of high-speed signals between multiple signal channels on the second flexible circuit board 370 facilitates reducing crosstalk between adjacent high-speed signal line groups on the second flexible circuit board 370 .

In some embodiments, a projection of a third hollowed out area on the second base body covers a projection of a corresponding fourth hollowed out area on the second base body. Exemplarily, the projection of the third hollowed out area on the second base coincides with the projection of the fourth hollowed out area on the second base, so that the rigidity of each part of the second flexible circuit board 370 is relatively uniform, thereby avoiding the first The second flexible circuit board 370 breaks when subjected to strong bending.

For the structural description and beneficial effects of the second flexible circuit board 370 in some embodiments of the present disclosure, please refer to the description of the first flexible circuit board 360 .

In some embodiments, the third flexible circuit board 380 includes a third substrate, a fifth metal layer disposed on the first surface of the third substrate, and a sixth metal layer disposed on the second surface of the third substrate. The fifth metal layer includes at least one low-speed signal line group and at least one fifth reference ground, and a fifth reference ground is provided on both sides of a low-speed signal line group, so that different low-speed signal lines on the third flexible circuit board 380 Groups are spaced apart. The fifth metal layer also includes at least one fifth hollowed out area, at least one fifth hollowed out area is located in the corresponding fifth reference ground; no metal is set in the fifth hollowed out area, that is, the fifth metal layer is located in the fifth hollowed out area. Area locations are hollowed out. The sixth metal layer includes at least one sixth reference ground and at least one sixth hollowed out area, at least one sixth hollowed out area is located in the corresponding sixth reference ground; no metal is set in the sixth hollowed out area, that is, the sixth metal The layer is hollowed out at the location of the sixth hollowed out region. By setting the fifth hollowed out area on the fifth reference ground and the sixth hollowed out area on the sixth reference ground, the area where metal is laid on the third flexible circuit board 380 is reduced, thereby reducing the rigidity of the third flexible circuit board 380 , to prevent the third flexible circuit board 380 from being broken when subjected to strong bending.

In some embodiments, the structure description and beneficial effect of the third flexible circuit board 380 can refer to the description of the first flexible circuit board 360 .

Figure 17 is an exploded view of an optical module and a flexible circuit board according to some embodiments. As shown in Figure 17, in the optical module 200, the light emitting device 400 includes an electrical connector 420, the light emitting device 400 is connected to the first flexible circuit board 360 and the third flexible circuit board 380 through the electrical connector 420, and the electrical connector 420 It is configured to realize electrical connection of the light emitting device 400 with the first flexible circuit board 360 and the third flexible circuit board 380 . Exemplarily, the electrical connector 420 includes a boss 421 configured to connect the first flexible circuit board 360 and the third flexible circuit board 380 . The boss 421 includes a first connection surface 4211 and a second connection surface 4212, the first connection surface 4211 and the second connection surface 4212 respectively include pads, one end of the first flexible circuit board 360 is welded on the first connection surface 4211, the second One end of the three flexible circuit boards 380 is welded on the second connection surface 4212 . The first connection surface 4211 and the second connection surface 4212 respectively form steps with the top surface and the bottom surface of the electrical connector 420, and the steps are configured to limit the ends of the first flexible circuit board 360 and the third flexible circuit board 380, thereby facilitating The first flexible circuit board 360 and the third flexible circuit board 380 are soldered to the electrical connector 420 .

In some embodiments, the light receiving device 500 includes an opening 520 , that is, the cavity of the light receiving device 500 is provided with the opening 520 , and one end of the second flexible circuit board 370 passes through the opening 520 . One end of the second flexible circuit board 370 is inserted into and fixed in the cavity of the light receiving device 500 to be electrically connected with electrical devices such as a light receiving chip and a transimpedance amplifier, and the other end of the second flexible circuit board 370 is electrically connected to the circuit board 300 .

FIG. 18 is a block diagram of a circuit board according to some embodiments. As shown in FIG. 18 , the circuit board 300 includes a first soldering area 391 , a second soldering area 393 and a third soldering area 392 located on the top surface of the circuit board 300 . The first welding area 391 , the second welding area 393 and the third welding area 392 are arranged in parallel at the end of the circuit board 300 , and the second welding area 393 is located at the leftmost end of the circuit board 300 . The first welding area 391 is configured to solder the other end of the first flexible circuit board 360, the second welding area 393 is configured to solder the other end of the second flexible circuit board 370, and the third welding area 392 is configured to be soldered. the other end of the third flexible circuit board 380 . The first welding area 391, the second welding area 393 and the third welding area 392 are arranged on the same side of the circuit board 300 and are all arranged at the end of the circuit board 300, which is conducive to optimizing the layout of the circuit board 300 and improving the layout of the circuit board 300. space utilization. In other embodiments, the first soldering area 391 , the second soldering area 393 and the third soldering area 392 are not limited to be disposed at the end of the top surface of the circuit board 300 , and may also be disposed at the end of the bottom surface of the circuit board 300 . The first welding area 391 , the second welding area 393 and the third welding area 392 are arranged on the same surface of the circuit board 300 to facilitate the welding of the first flexible circuit board 360 , the second flexible circuit board 370 and the third flexible circuit board 380 .

The circuit board 300 includes high-speed signal lines respectively located on its top surface and bottom surface, that is, the top surface of the circuit board 300 is provided with a high-speed signal line directly electrically connected to the first welding area 391, and the bottom surface of the circuit board 300 is arranged with the third welding area 392. Electrically connected high-speed signal lines, the high-speed signal lines laid on the bottom surface of the circuit board 300 are electrically connected to the third welding area 392 through via holes. In some other embodiments, the third welding area 392 can also be arranged on the bottom surface of the circuit board 300 , and the second welding area 393 can also be arranged on the bottom surface of the circuit board 300 . Furthermore, the first welding zone 391 and the third welding zone 392 can be located on different sides of the circuit board 300, and the second welding zone 393 can be located on the same surface as the first welding zone 391 on the circuit board 300, or can be located on the same surface as the third welding zone 392. different sides of the circuit board 300 .

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present disclosure, rather than to limit them; although the present disclosure has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: it can still Modifications are made to the technical solutions described in the foregoing embodiments, or equivalent replacements are made to some of the technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the various embodiments of the present invention.

Claims (20)

1. An optical module, comprising:

   case;

   The circuit board is arranged in the housing, the circuit board includes a plurality of board layers, and the plurality of board layers includes a top layer, a bottom layer, and at least one intermediate layer between the top layer and the bottom layer, each adjacent The two plies are insulated from each other; where,

   The circuit board also includes:

   a ground layer in the at least one intermediate layer;

   a signal line located in the top layer or the bottom layer;

   The signal gold finger is located in the same board layer as the signal line, is arranged at one end of the signal line and is electrically connected to the signal line;

   A ground wire, located in the same board layer as the signal wire, is arranged on at least one side of the signal wire and is electrically connected to the ground layer through a ground via hole;

   The grounding gold finger is located in the same board layer as the signal line, is arranged at one end of the grounding line and is electrically connected to the grounding line, and is arranged adjacent to the signal gold finger; and

   A return hole, the projection of the return hole on the at least one intermediate layer is located in the projection area of the grounding gold finger on the at least one intermediate layer, one end of the return hole is connected to the grounding gold finger but The other end of the return hole passes through one or more intermediate layers of the at least one intermediate layer and is electrically connected to the ground layer without penetrating through the grounding gold finger.
2. The optical module according to claim 1, wherein,

   The signal lines include positive differential signal lines and negative differential signal lines;

   The ground wire includes a first sub-ground wire and a second sub-ground wire;

   The first sub-ground wire is arranged at one end of the positive differential signal line and is electrically connected to the positive differential signal line, and the second sub-ground wire is arranged at one end of the negative differential signal line and is electrically connected to the negative differential signal line. The differential signal lines are electrically connected, and the positive differential signal line and the negative differential signal line are located between the first sub-ground line and the second sub-ground line.
3. The optical module according to claim 1 or 2, wherein,

   The grounding gold finger includes a first sub-grounding gold finger and a second sub-grounding gold finger;

   The signal gold fingers include positive differential signal gold fingers and negative differential signal gold fingers;

   One end of the first sub-ground wire is electrically connected to the first sub-ground gold finger, one end of the second sub-ground wire is electrically connected to the second sub-ground gold finger, and one end of the positive differential signal line It is electrically connected to the positive differential signal gold finger, and one end of the negative differential signal line is electrically connected to the negative differential signal gold finger.
4. The optical module according to claim 3, wherein the circuit board includes a plurality of return holes, at least two return holes in the plurality of return holes form a first return hole group;

   The projection of the first return hole group on the at least one intermediate layer is located in the projection area of the first sub-ground gold finger on the intermediate layer; one end of the first return hole group is connected to the second A sub-ground gold finger is electrically connected, and the other end of the first return hole group is connected to the ground layer.
5. The optical module according to claim 4, wherein the distance between two adjacent reflow holes in the first reflow hole group is the same.
6. The optical module according to claim 5, wherein the at least two return holes in the first return hole group are located in a row;

   The distance between the two return holes located at two ends of the first return hole group and the two ends of the first sub-ground gold finger is the same as the distance between two adjacent return holes.
7. The optical module according to any one of claims 4-6, wherein a diameter of each return hole in the first return hole group is smaller than a width of the first sub-ground gold finger.
8. The optical module according to claim 7, wherein the diameter of each return hole is in the range of 3mil to 8mil.
9. The optical module according to claim 4, wherein at least two of the plurality of return holes form a second return hole group;

   The projection of the second return hole group on the at least one intermediate layer is located in the projection area of the second sub-ground gold finger on the intermediate layer; one end of the second return hole group is connected to the first A sub-ground gold finger is electrically connected, and the other end of the second return hole group is connected to the ground layer.
10. The optical module according to claim 1, wherein the distance between the end of the signal gold finger away from the signal line and the end of the circuit board is greater than the distance between the end of the ground gold finger away from the ground line and the end of the circuit board. distance from the end of the board.
11. The optical module according to claim 1, further comprising:

    an optical emitting device, electrically connected to the circuit board, configured to emit optical signals to the outside of the optical module;

    a light receiving device, electrically connected to the circuit board, stacked with the light emitting device, and configured to receive an optical signal from outside the optical module; and

    A flexible circuit board, one end of the flexible circuit board is electrically connected to the light emitting device and the light receiving device, and the other end of the flexible circuit board is electrically connected to the circuit board.
12. The optical module according to claim 11, wherein the flexible circuit board comprises:

    A first flexible circuit board, one end of the first flexible circuit board is electrically connected to the light-emitting device, and the other end of the first flexible circuit board is electrically connected to the circuit board;

    a second flexible circuit board, one end of the second flexible circuit board is electrically connected to the light receiving device, and the other end of the second flexible circuit board is electrically connected to the circuit board;

    A third flexible circuit board, one end of the third flexible circuit board is electrically connected to the light-emitting device, the other end of the first flexible circuit board is electrically connected to the circuit board, and the third flexible circuit board It is arranged between the first flexible circuit board and the second flexible circuit board.
13. The optical module according to claim 12, wherein the first flexible circuit board comprises:

    first substrate;

    The first metal layer, located on the first surface of the first substrate, includes at least one high-speed signal line group, at least one first reference ground, and at least one first hollowed out area, and both sides of a high-speed signal line group are arranged There is a first reference ground, the at least one first hollowed out area is located in the corresponding first reference ground, and no metal is arranged in the at least one first hollowed out area; and

    The second metal layer, located on the second surface of the first substrate opposite to the first surface, includes at least one second reference ground and at least one second hollowed out area, and the at least one second hollowed out area Located in the corresponding second reference ground, no metal is arranged in the at least one second hollowed-out area.
14. The optical module according to claim 13, wherein the at least one first hollowed out area is evenly arranged in the at least one first reference ground, and the at least one second hollowed out area is evenly arranged in the at least one first reference ground At least one second reference ground.
15. The optical module according to claim 13 or 14, wherein the projection of a second reference ground on the first substrate covers the projection of the corresponding high-speed signal line group on the first substrate.
16. The optical module according to any one of claims 13-15, wherein a trace width of a first reference ground is greater than a trace width of an adjacent high-speed signal line group.
17. The optical module according to any one of claims 13-16, wherein a projection of a second reference ground on the first substrate covers a projection of a corresponding first reference ground on the first substrate.
18. The optical module according to any one of claims 13-17, wherein the first flexible circuit board further includes a via hole, and the via hole is located in a region where a second reference ground coincides with a corresponding first reference ground , so that the second reference ground is electrically connected to the corresponding first reference ground.
19. The optical module according to any one of claims 13-18, wherein a projection of a second hollowed out area on the first base body covers a projection of a corresponding first hollowed out area on the first base body.
20. The optical module according to any one of claims 13-19, wherein the second flexible circuit board comprises:

    second substrate;

    The third metal layer, located on the first surface of the second substrate, includes at least one third reference ground and at least one third hollowed out area, and the at least one third hollowed out area is located in the corresponding third reference ground , no metal is disposed in the at least one third hollowed-out region; and

    The fourth metal layer, located on the second surface of the second base body opposite to the first surface, includes at least one high-speed signal line group, at least one fourth reference ground and at least one fourth hollowed out area, a high-speed Both sides of the signal line group are provided with a fourth reference ground, the at least one fourth hollowed out area is located in the corresponding fourth reference ground, and no metal is arranged in the at least one fourth hollowed out area;

    The third metal layer is arranged opposite to the second metal layer.

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