WO2023185216A1 - 一种光模块 - Google Patents

一种光模块 Download PDF

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Publication number
WO2023185216A1
WO2023185216A1 PCT/CN2023/072133 CN2023072133W WO2023185216A1 WO 2023185216 A1 WO2023185216 A1 WO 2023185216A1 CN 2023072133 W CN2023072133 W CN 2023072133W WO 2023185216 A1 WO2023185216 A1 WO 2023185216A1
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WO
WIPO (PCT)
Prior art keywords
frequency signal
circuit board
width
connection area
pin
Prior art date
Application number
PCT/CN2023/072133
Other languages
English (en)
French (fr)
Inventor
王雪阳
姚建伟
于冬梅
邵宇辰
王欣南
张加傲
于琳
Original Assignee
青岛海信宽带多媒体技术有限公司
Priority date (The priority date is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the date listed.)
Filing date
Publication date
Priority claimed from CN202210343045.3A external-priority patent/CN114879321B/zh
Priority claimed from CN202210709079.XA external-priority patent/CN115236808A/zh
Application filed by 青岛海信宽带多媒体技术有限公司 filed Critical 青岛海信宽带多媒体技术有限公司
Publication of WO2023185216A1 publication Critical patent/WO2023185216A1/zh

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Classifications

    • G—PHYSICS
    • G02—OPTICS
    • G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
    • G02B6/00—Light guides; Structural details of arrangements comprising light guides and other optical elements, e.g. couplings
    • G02B6/24—Coupling light guides
    • G02B6/42—Coupling light guides with opto-electronic elements

Definitions

  • the present disclosure relates to the field of optical communication technology, and in particular, to an optical module.
  • optical communication technology optical modules are tools for realizing mutual conversion of optical and electrical signals. They are 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.
  • an embodiment of the present disclosure provides an optical module, including: a circuit board including: a first signal pad; a flexible circuit board, one end connected to the circuit board, including: a second conductive layer provided with a first signal lead; The pin is connected to the first signal pad through the first solder; the ground conductive area is located on one side of the first signal pin; the second covering film is attached to the lower surface of the second conductive layer; the edge of the second covering film Disposed between the first signal pin and the ground conductive area; the second cover film does not cover the first signal pin, and the second cover film does not cover the first signal pad; the second cover film covers the ground conductive area.
  • embodiments of the present disclosure also provide an optical module, including: a circuit board; a light emitting component electrically connected to the circuit board for converting electrical signals into optical signals; and a flexible circuit board electrically connected to the circuit board and the light emitting component.
  • the component has: a first high-frequency signal line; a first high-frequency signal pad; a first connection area and a second connection area between the first high-frequency signal line and the first high-frequency signal pad; A high-frequency signal line, the first connection area, the second connection area and the first high-frequency signal pad are connected in sequence, The width of the first high-frequency signal pad is greater than the width of the first high-frequency signal line.
  • the width of one end of the first connection area is the same as the width of the first high-frequency signal line, and the width of the other end is the same as the width of the second connection area.
  • the width of the second connection area is greater than The first high frequency signal pad width.
  • Figure 1 is a connection diagram of an optical communication system according to some embodiments.
  • Figure 2 is a structural diagram of an optical network terminal according to some embodiments.
  • Figure 3 is a structural diagram of an optical module according to some embodiments.
  • Figure 4 is an exploded view of an optical module according to some embodiments.
  • Figure 5 is a schematic diagram of the internal structure of an optical module according to some embodiments.
  • Figure 6 is a schematic diagram of the connection between a light emitting component and a flexible circuit board according to some embodiments
  • Figure 7 is a schematic cross-sectional structural diagram of a flexible circuit board according to some embodiments.
  • Figure 8 is a schematic partial structural diagram of the Bottom surface of a flexible circuit board according to some embodiments.
  • Figure 9 is a schematic diagram 2 of the partial structure of the Bottom surface of a flexible circuit board according to some embodiments.
  • Figure 10 is a partial cross-sectional schematic diagram of the connection between a circuit board and a flexible circuit board according to some embodiments
  • Figure 11 is a partial cross-sectional schematic diagram 2 of the connection between a circuit board and a flexible circuit board according to some embodiments;
  • Figure 12 is a partial cross-sectional schematic diagram 3 of the connection between a circuit board and a flexible circuit board according to some embodiments;
  • Figure 13 is a schematic diagram of the connection between a flexible circuit board and a circuit board according to some embodiments.
  • Figure 14 is a surface structure diagram of a flexible circuit board according to some embodiments.
  • Figure 15 is an enlarged schematic diagram of a surface structure of a flexible circuit board according to some embodiments.
  • Figure 16 is another surface structure diagram of a flexible circuit board according to some embodiments.
  • Figure 17 is a schematic diagram of simulation results of a flexible circuit board according to some embodiments.
  • Figure 18 is a schematic diagram 2 of simulation results of a flexible circuit board according to some embodiments.
  • first and second are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Therefore, features 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.
  • connection and its derivatives may be used.
  • some embodiments may be described using the term “connected” to indicate that two or more components are in direct physical or electrical contact with each other.
  • a and/or B includes the following three combinations: A only, B only, and a combination of A and B.
  • optical signals are used to carry the information to be transmitted, and the optical signals carrying the information are transmitted to information processing equipment such as computers through information transmission equipment such as optical fibers or optical waveguides to complete the process.
  • Transmission of information Since light has passive transmission characteristics when transmitted through optical fibers or optical waveguides, low-cost, low-loss information transmission can be achieved.
  • 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 computers and other information processing equipment are electrical signals. Therefore, in order to distinguish between information transmission equipment such as optical fibers or optical waveguides and computers and other information processing equipment To establish an information connection between them, it is necessary to realize the mutual conversion of electrical signals and optical signals.
  • Optical modules realize the mutual conversion function of the above-mentioned optical signals and electrical signals in the field of optical communication technology.
  • 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 (for example, optical modem) through the electrical port.
  • the electrical connection Mainly used for power supply, I2C signal transmission, data information transmission and grounding; optical network terminals transmit electrical signals to computers and other information processing equipment through network cables or wireless fidelity technology (Wi-Fi).
  • Figure 1 is a connection diagram of an optical communication system.
  • 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.
  • 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.
  • the optical fiber itself can support long-distance signal transmission, such as signal transmission of thousands of meters (6 kilometers to 8 kilometers). On this basis, if a repeater is used, unlimited distance transmission can be theoretically achieved. Therefore, in a common optical communication system, the distance between the remote server 1000 and the optical network terminal 100 can usually reach several kilometers, tens of kilometers, or hundreds of kilometers.
  • the local information processing device 2000 can be any one or more of the following devices: router, switch, computer, mobile phone, tablet computer, television, etc.
  • 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 module 200 includes an optical port and an electrical port.
  • the optical port is configured to access the optical fiber 101, so that the optical module 200 establishes a bidirectional optical signal connection with the optical fiber 101;
  • the electrical port is configured to access the optical network terminal 100, so that The optical module 200 establishes a bidirectional electrical signal connection with the optical network terminal 100 .
  • the optical module 200 realizes mutual conversion between optical signals and electrical signals, thereby enabling the connection between the optical fiber 101 and the optical network terminal 100 Establish information connections between them. 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.
  • 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 converting optical signals and electrical signals and does not have the function of processing data, the information does not change during the above-mentioned photoelectric conversion process.
  • the optical network terminal 100 includes a substantially rectangular parallelepiped housing, and an optical module interface 102 and a network cable interface 104 provided on the housing.
  • the optical module interface 102 is configured to access the optical module 200, so that the optical network terminal 100 and the optical module 200 establish a bidirectional electrical signal connection;
  • the network cable interface 104 is configured to access the network cable 103, so that the optical network terminal 100 and the network cable 103 Establish a two-way electrical signal connection.
  • the optical module 200 and the network cable 103 are connected through the optical network terminal 100 .
  • 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. Therefore, the optical network terminal 100 serves as the host computer of the optical module 200 and can monitor the optical module. 200 job.
  • the host computer of the optical module 200 may also include an optical line terminal (Optical Line Terminal, OLT), etc.
  • the remote server 1000 establishes a bidirectional 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.
  • Figure 2 is a structural diagram of an optical network terminal. In order to clearly show the connection relationship between the optical module 200 and the optical network terminal 100, Figure 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 provided in the housing, a cage 106 provided on the surface of the circuit board 105, a heat sink 107 provided on the cage 106, and electrical connections provided inside 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 fins and other protrusions that increase 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 heat sink 107.
  • the electrical port of the optical module 200 is connected to the electrical connector inside the cage 106, so that the optical module 200 and the optical network terminal 100 establish a bidirectional electrical signal connection.
  • the optical port of the optical module 200 is connected to the optical fiber 101, so that the optical module 200 and the optical fiber 101 establish a bidirectional optical signal connection.
  • Figure 3 is a structural diagram of an optical module according to some embodiments
  • Figure 4 is a diagram of an optical module according to some embodiments.
  • the optical module 200 includes a shell, a circuit board 105 and an optical transceiver component 400 disposed in the shell.
  • the housing includes an upper housing 201 and a lower housing 202.
  • the upper housing 201 is covered on the lower housing 202 to form the above-mentioned housing with two openings; the outer contour of the housing generally presents a square body.
  • 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 is closed On the two lower side plates 2022 of the lower housing 202, the above-mentioned housing is formed.
  • 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 two lower side plates 2022 located on both sides of the cover plate 2011.
  • the two upper side plates of the cover plate 2011 are vertically arranged, and are combined with the two lower side plates 2022 to realize that the upper housing 201 is covered on the lower housing 202 .
  • the direction of the connection line between the two openings 204 and 205 may be consistent with the length direction of the optical module 200 , or may be inconsistent with the length direction of the optical module 200 .
  • the opening 204 is located at the end of the optical module 200 (the right end of FIG. 3 ), and the opening 205 is also located at the end of the optical module 200 (the left end of FIG. 3 ).
  • the opening 204 is located at an end of the optical module 200 and the opening 205 is located at a side of the optical module 200 .
  • the opening 204 is an electrical port, and the golden finger of the circuit board 105 extends from the electrical port 204 and is inserted into the host computer (for example, the optical network terminal 100); the opening 205 is an optical port configured to access the external optical fiber 101 so that the external The optical fiber 101 connects the optical transceiver component 400 inside the optical module 200.
  • the assembly method of combining the upper housing 201 and the lower housing 202 facilitates the installation of components such as the circuit board 105 and the optical transceiver assembly 400 into the housing.
  • the upper housing 201 and the lower housing 202 form packaging protection for these components.
  • the deployment of positioning components, heat dissipation components, and electromagnetic shielding components of these components is facilitated, which is conducive to automated production.
  • the upper housing 201 and the lower housing 202 are generally made of metal materials, which facilitates electromagnetic shielding and heat dissipation.
  • the optical module 200 also includes an unlocking component located outside its housing.
  • the unlocking component is configured to achieve a fixed connection between the optical module 200 and the host computer, or to release the fixation between the optical module 200 and the host computer. connect.
  • the unlocking component is located on the outer walls of the two lower side plates 2022 of the lower housing 202 and has a A snap component that matches the host computer cage (for example, the cage 106 of the optical network terminal 100).
  • the optical module 200 is inserted into the cage of the host computer, the optical module 200 is fixed in the cage of the host computer by the engaging parts of the unlocking part.
  • the engaging parts of the unlocking part move accordingly, thereby changing the engaging parts.
  • the connection relationship with the host computer is to release the engagement relationship between the optical module 200 and the host computer, so that the optical module 200 can be pulled out from the cage of the host computer.
  • Figure 5 is a schematic diagram of the internal structure of an optical module provided by an embodiment of the present disclosure.
  • the optical transceiver component 300 includes a round square tube body 310.
  • the light emitting component 400 and the light receiving component 500 are embedded in the round square tube body 310.
  • the light emitting component 400 and the light receiving component 500 are electrically connected to the circuit board 105 through the flexible circuit board 600 respectively, so that the light emitting component 400 is used to output signal light and the light receiving component 500 is used to receive signal light from outside the optical module to realize the optical module.
  • Electro-optical and photoelectric conversion a lens assembly is usually provided in the round tube body 310, and the lens assembly is used to change the propagation direction of the signal light output by the light emitting assembly 400 or the signal light input by an external optical fiber.
  • One end of the flexible circuit board 600 is electrically connected to the light emitting component 400 or the light receiving component 500, and the other end is electrically connected to the circuit board 105, thereby realizing the electrical connection between the light emitting component 400 or the light receiving component 500 and the circuit board 105; specifically, the flexible circuit board 600 is electrically connected to the light emitting component 400 or the light receiving component 500.
  • the circuit board 600 includes a first connection part and a second connection part, the first connection part is electrically connected to the light emitting component 400 or the light receiving component 500, the second connection part is electrically connected to the circuit board 105; the first connection part and the second connection part
  • the flexible circuit boards 600 are provided with corresponding pads respectively, and the first connection part is electrically connected to the light emitting component 400 or the light receiving component 500 through the pads, and the second connection part is electrically connected to the circuit board 105;
  • the flexible circuit board 600 is provided with a first Insulating dielectric layer, a metal via is provided between the top surface and the bottom surface of the first insulating dielectric layer, and a second insulating dielectric layer is provided inside the circuit board 105.
  • the electrical signal passes through the top surface of the circuit board 105.
  • the surface is transmitted to the bottom surface of the flexible circuit board 600, and then through the metal via hole, transmitted to the top surface of the flexible circuit board 600, and then transmitted to the light emitting component 400 through the high-frequency signal line on the surface of the flexible circuit board 600.
  • the light emitting component 400 After receiving the electrical signal, the laser in it converts the electrical signal into an optical signal and transmits it to the outside of the optical module.
  • Pin through holes include laser anode pin through holes, laser cathode pin through holes, low frequency signal pin through holes and ground pin through holes.
  • the laser anode pin passes through the laser anode pin through hole, and Weld and connect with the laser positive signal pad;
  • the laser negative pin passes through the laser negative pin through hole and is welded and connected with the laser negative signal pad;
  • the low frequency signal pin passes through the low frequency signal pin through hole and is welded with the low frequency signal Pan welding connection.
  • the laser positive signal pad is the laser positive signal pad 610
  • the laser negative signal pad is the laser negative signal pad 640
  • Figure 14 also includes a grounding through hole 693, on the tube base
  • the ground pin passes through the ground through hole 693, one end of the ground through hole 693 is connected to the ground plane, and then the tube base is electrically connected to the ground plane through the ground pin;
  • the ground plane is the ground layer 690 in Figure 17, and the ground layer 690 and the ground pad 691 and ground pad 692 are electrically connected, and then ground pad 691 and ground pad 692 are electrically connected to ground on the circuit board 105 .
  • the circuit board 105 includes circuit wiring, electronic components and chips.
  • the electronic components and chips are connected together according to the circuit design through the circuit wiring to realize functions such as power supply, electrical signal transmission and grounding.
  • Electronic components include, for example, capacitors, resistors, transistors, and metal-oxide-semiconductor field-effect transistors (MOSFETs).
  • Chips include, for example, microcontroller units (MCU), laser driver chips, limiting amplifiers, clock and data recovery (Clock and Data Recovery, CDR) chips, power management chips, digital signal processing, DSP) chip.
  • MCU microcontroller units
  • CDR clock and Data Recovery
  • DSP digital signal processing
  • the circuit board 105 is generally a rigid circuit board. Due to its relatively hard material, the rigid circuit board can also perform a load-bearing function. For example, the rigid circuit board can smoothly carry the above-mentioned electronic components and chips; when the optical transceiver component is located on the circuit board, the rigid circuit board The circuit board can also provide smooth loading; the rigid circuit board can also be inserted into the electrical connector in the host computer cage.
  • the circuit board 105 also includes gold fingers formed on its end surface, and the gold fingers are composed of a plurality of mutually independent pins.
  • the circuit board 105 is inserted into the cage 106 and is electrically connected to the electrical connector in the cage 106 by the gold finger.
  • the golden fingers can be provided only on one side of the circuit board 105 (for example, the upper surface shown in FIG. 4 ), or they can be provided on the upper and lower surfaces of the circuit board 105 to adapt to situations where a large number of pins are required.
  • the golden finger is configured to establish an electrical connection with the host computer to realize power supply, grounding, I2C signal transmission, data signal transmission, etc.
  • flexible circuit boards are also used in some optical modules.
  • Flexible circuit boards are generally used in conjunction with rigid circuit boards as a supplement to rigid circuit boards. Of course, flexible circuit boards are also used in some optical modules. Flexible circuit boards are generally used in conjunction with rigid circuit boards as a supplement to rigid circuit boards. For example, a flexible circuit board can be used to connect the rigid circuit board and the optical transceiver component.
  • the optical transceiver component 400 includes a light emitting device and a light receiving device.
  • the light emitting device is configured to transmit an optical signal
  • the light receiving device is configured to receive an optical signal.
  • the light emitting device and the light receiving device are combined together to form an integrated optical transceiver component.
  • a flexible circuit board is usually provided to connect with the circuit board.
  • One end of the flexible circuit board is provided with a gold finger.
  • the uppermost metal layer is defined as the TOP layer 520
  • the lowermost metal layer is defined as the Bottom layer 540.
  • the TOP layer 520 and the Bottom layer 540 are electrically connected through via holes.
  • the first covering film 510 is attached above the TOP layer 520
  • the second covering film 550 is provided below the Bottom layer 540 .
  • the Bottom layer 540 of the flexible circuit board is connected to the corresponding pad on the circuit board through solder.
  • the signal line pins include impedance signal pins and non-impedance signal pins.
  • the impedance signal pins are signals connected by signal lines with impedance matching requirements. Pins, such as the driving signal of the laser chip and the driving signal of the transimpedance amplifier chip. Impedance matching signal lines need to match impedance to reduce signal noise and improve communication stability.
  • the flexible circuit board includes: a first conductive layer connected to the light emitting device and/or the light receiving device; a second conductive layer located below the first conductive layer and provided with a first signal pin connected to the first signal pad ;
  • the second covering film is attached to the lower surface of the second conductive layer.
  • the isolation layer 530 disposed between the first conductive layer and the second conductive layer is the base material of the flexible circuit board. The second cover film does not cover the first signal pin, and the second cover film does not cover the first signal pad on the circuit board.
  • one or more intermediate conductive layers may be disposed between the first conductive layer and the second conductive layer.
  • the first conductive layer and the second conductive layer, the first conductive layer and the intermediate conductive layer , the second conductive layer and the intermediate conductive layer are electrically connected through via holes.
  • Figure 7 is a schematic cross-sectional structural diagram of a flexible circuit board provided by the present disclosure.
  • the structural schematic diagram of the flexible circuit board is shown in Figure 7, which includes at least two metal layers.
  • the uppermost metal layer, that is, the first conductive layer is the TOP layer 520
  • the bottom metal layer is the TOP layer 520.
  • the second conductive layer is the Bottom layer 540
  • an isolation layer 530 is provided between the TOP layer 520 and the Bottom layer 540.
  • the first cover film 510 is covered on the upper surface of the TOP layer 520
  • the second cover film 550 is provided on the lower surface of the Bottom layer 540 .
  • Figure 8 is a schematic diagram of the partial structure of the bottom surface of the flexible circuit board provided by the present disclosure.
  • one end of the flexible circuit board is equipped with gold fingers, including ground pin 541 and non-impedance signal pins. 542 and impedance signal pin 543.
  • the ground pin 541, the non-impedance signal pin 542 and the impedance signal pin 543 are flush with one end close to the end of the flexible circuit board, and are not flush with the other end.
  • the left side of the golden finger shown in Figure 8 is called the first end, and the right side is called the second end.
  • the second ends of the ground pin 541, the non-impedance signal pin 542 and the impedance signal pin 543 are set flush, and the first ends are not flush.
  • the other end of the ground pin 541 is connected to the ground conductive area 544 .
  • the impedance signal pin 543 is provided with a first via 5431 and is connected to the impedance matching signal line.
  • the impedance matching signal line of the flexible circuit board is provided on the TOP layer 520 .
  • the non-impedance signal pin 542 is provided with a second via 5421, which is connected to the non-impedance matching signal line.
  • a second covering film 550 is provided on the surface of the Bottom layer 540 to cover part of the Bottom layer.
  • the impedance matching signal line and the non-impedance matching signal line are provided on the TOP layer 520 .
  • ground conductive area 544 is greater than the width of ground pin 541 .
  • the second covering film 550 does not cover the impedance signal pin 543 and does not cover the first via hole 5431 .
  • the second covering film 550 does not cover the impedance signal pin, the impedance matching pad on the circuit board and the impedance signal pin are connected through the first solder, and the absence of the first solder connection is caused by the second covering film 550
  • the stumps are conducive to reducing the noise impact caused by the stumps.
  • the second covering film 550 covers part of the non-impedance signal pins to increase the non-impedance
  • the connection area between the signal pin and the flexible circuit board enhances the connection stress between the non-impedance signal pin and the flexible circuit board, which can effectively prevent the signal pin from falling off the flexible board after being stressed.
  • the solder is connected to the gold fingers and toes of the flexible circuit board, and the stress is concentrated on the edge of the second covering film 550 , located at the connection between the second covering film 550 and the gold fingers and toes.
  • the first ends of the non-impedance signal pin 542 and the ground pin 541 are pressed by the second covering film 550, and the impedance signal pin 543 is away from the stress concentration point, thereby preventing all signal pins on the flexible circuit board from falling off.
  • the second covering film 550 covers part of the ground pin 541, and the exposed part of the ground pin 541 is soldered to the circuit board through a third solder.
  • the ground conductive area has a large extension area, and the second covering film 550 completely covers the ground conductive area, the ground signal line, and partially covers the ground pin 541 .
  • the second covering film 550 covers part of the non-impedance signal pin 542 and does not cover the second via hole 5421 . In this way, non-impedance signals lead to A first stub is formed between the pin 542 and the second covering film 550, and a second stub is formed between the second covering film 550 and the second signal pad.
  • the non-impedance signal When the non-impedance signal is transmitted from the circuit board to the flexible circuit board, An open signal flow is formed at the first stub and the second stub, generating signal noise.
  • the second covering film 550 covers part of the non-impedance signal pin 542, thereby enhancing the connection stress between the non-impedance signal pin 542 and the flexible circuit board isolation layer 530.
  • the non-impedance signal pin 542 is connected to the second signal pad through a second solder.
  • the second covering film 550 does not cover the impedance signal pin 543 and does not cover the first via hole 5431 .
  • a second covering film 550 is provided between the non-impedance signal pin 542 and the second signal pad on the circuit board.
  • the non-impedance signal is transmitted from the circuit board to the flexible circuit board, it passes through the first stub.
  • An open-circuit signal flow is formed at the second stub, resulting in signal noise.
  • the second covering film 550 does not cover the impedance signal pin.
  • the impedance matching pad on the circuit board and the impedance signal pin are connected through the first solder. There is no stub caused by the second covering film 550 at the first solder connection. It is helpful to reduce the noise impact caused by stumps.
  • the impedance signal pin is the first signal pin
  • the non-impedance signal pin is the second signal pin
  • the ground pin is the third signal pin.
  • the impedance signal pad is the first signal pad
  • the non-impedance signal pad is the second signal pad
  • the ground pad is the third signal pad.
  • the minimum tolerance of the board manufacturer when laminating the flexible circuit board covering film is ⁇ i, and the minimum length of the annular ring of the tin penetration hole on the pad is j.
  • the designed pad length must ensure the integrity of the annular ring and cannot break it.
  • the board factory's process capability i is greater than j.
  • the minimum length of the edge of the second covering film pressed against the non-impedance signal pin is i
  • the minimum length of the edge of the second covering film pressed against the ground pin is i
  • the shortest edge from the edge of the second covering film to the inner wall of the first via hole The distance is i, so within the fit tolerance range, the second covering film can press the non-impedance signal pins and ground pins (which can prevent the independent pins from falling off due to external pulling force), and at the same time press It covers the grounded conductive area to prevent the gold finger of the Flexible Printed Circuit Board (FPC) from being exposed to the ground copper and causing continuous soldering; it also prevents the second covering film from covering the first via hole and affecting the tin penetration of the pad.
  • the ground conductive area should be kept at a minimum distance from the finger pad according to the etching circuit capabilities
  • Figure 9 is a schematic diagram 2 of the partial structure of the bottom surface of the flexible circuit board provided by the present disclosure. As shown in Figure 9 As shown in , in some embodiments of the present disclosure, taking the inner wall of the via hole close to the second covering film 550 as a reference, the distance between the first end of the impedance signal pin 543 and the inner wall of the hole from the first via hole is a second distance. b (Ensure the integrity of the via hole ring and not break the hole).
  • the distance between the edge of the second covering film 550 and the edge of the impedance signal pin 543 is the first spacing a, and the distance between the edge of the ground conductive area and the edge of the second covering film 550 is the third spacing c, to ensure that the covering film fit tolerance range Even if the impedance signal pin is not pressed, it can also press the ground conductive area to prevent soldering, thereby only forming a short unavoidable stub on the impedance matching signal line.
  • the second covering film 550 can be set to cover the non-impedance signal pin 542 with a length of the fourth spacing e, that is, the second covering film 550 covers the non-impedance signal pin 542, and the second covering film 550
  • the distance between the edge of and the edge of the non-impedance signal line is e.
  • the numerical values of the first distance a and the third distance c may be the same or different.
  • the numerical values of the first distance a and the fourth distance e may be the same or different.
  • the values of the fourth distance e and the third distance c may be the same or different.
  • the edges of the second covering film 550 are arranged flush, that is, the edges of the second covering film 550 are arranged parallel to the edge of the gold finger end. As shown in FIG. 9 , the right edge of the second cover film 550 is arranged parallel to the right end edge of the golden finger.
  • the first spacing a, the third spacing c and the fourth spacing e have the same numerical value.
  • the first pitch a is equal to the third pitch c, and the third pitch c is smaller than the fourth pitch e.
  • the distance between the ground conductive area and the impedance signal pin should be greater than or equal to 2i; the distance between the edge of the second covering film 550 and the edge of the impedance signal pin 543 should be greater than or equal to the minimum tolerance i of the flexible circuit board covering film. ; The distance between the edge of the ground conductive area and the edge of the second covering film 550 is greater than or equal to the minimum tolerance i of the flexible circuit board covering film.
  • the second covering film can not only press the non-impedance signal pins and ground pins (to prevent independent pins from falling off due to external pulling force), but also press the ground conductive area to prevent the copper from being exposed when welding the FPC gold finger and causing continuous welding; and to prevent the second covering film from covering the first via hole and affecting the soldering pad from tin infiltration.
  • the ground conductive area should be kept at a minimum distance from the finger pad according to the etching circuit capabilities of the board manufacturer to ensure the integrity of the reference ground.
  • the distance between the edge of the second covering film and the edge of the first signal pin is equal to the distance between the edge of the second covering film and the edge of the ground conductive area, and the distance between the edge of the ground conductive area and the edge of the first signal pin is greater than Or equal to twice the process tolerance of the cover film.
  • the edge of the second covering film is located at the center of the edge of the ground conductive area and the edge of the first signal pin to prevent the second covering film from covering the impedance signal pin or causing the ground conductive area to be exposed.
  • the distance between the inner wall of the first via hole and the first end of the first signal pin is not zero, so as to prevent the first via hole from being damaged and affecting the penetration of tin from the first conductive layer to the second conductive layer.
  • the distance between the edge of the second covering film and the edge of the first signal pin is greater than the distance between the inner wall of the first via hole and the first end of the first signal pin.
  • the ground pin 541 is provided between the impedance signal pin 543 and the non-impedance signal pin 542 .
  • the circuit board provided by the present disclosure is provided with a non-impedance signal pad, an impedance signal pad and a ground pad. The non-impedance signal pad and the non-impedance signal pin are connected through the second solder, the impedance signal pin and the impedance signal pad are connected through the first solder, and the ground pad and the ground pin are connected through the third solder.
  • Figure 10 is a partial cross-sectional view of the connection between the circuit board and the flexible circuit board provided by the embodiment of the present disclosure.
  • Figure 11 is the partial cross-sectional view of the connection between the circuit board and the flexible circuit board provided by the embodiment of the present disclosure.
  • Figure 12 is the implementation of the present disclosure.
  • the example provides a partial cross-sectional diagram of the connection between the circuit board and the flexible circuit board.
  • Figure 10 is a schematic diagram of the connection between the impedance signal pad of the circuit board and the non-impedance signal pin of the flexible circuit board.
  • the non-impedance signal pad of the circuit board and the non-impedance signal pin of the flexible circuit board There is a second covering film 550 between 542, and two stumps appear at the upper and lower structures of the second covering film 550.
  • the arrow in Figure 10 shows a schematic diagram of non-impedance matching signal flow between the circuit board and the flexible circuit board.
  • a first stub 3013 is formed between the non-impedance signal pin 542 and the second covering film 550 ( Dotted line part), the second stub 3012 is formed between the second cover film 550 and the second signal pad (dotted line part), when the non-impedance signal is transmitted from the circuit board to the flexible circuit board, between the first stub and the second signal pad An open-circuit signal flow is formed at the second stump, resulting in signal noise.
  • the non-impedance matching signal passes from the non-impedance signal pad 301 of the circuit board through the second solder 3011 to the non-impedance signal pin 542 of the flexible circuit board, signal noise is caused at the second stump; the non-impedance matching signal is generated by the non-impedance signal When the pin 542 is transferred to the non-impedance signal line 521 of the TOP layer 520 through the first via hole 5421, a gap is formed between the first end of the non-impedance signal pin 542 covered by the second covering film 550 and the first via hole 5421. The first stump, Causes signal noise.
  • Figure 11 is a schematic diagram of the connection between the ground pad of the circuit board and the ground pin of the flexible circuit board. As shown in Figure 11, there is a second part between the ground pad 302 of the circuit board and the ground pin 541 of the flexible circuit board. Covering film 550 , the ground pad 302 of the circuit board and the ground pin 541 of the flexible circuit board are connected through a third solder 3021 .
  • Figure 12 is a schematic diagram of the connection between the impedance signal pad of the circuit board and the impedance signal pin of the flexible circuit board. As shown in Figure 12, the impedance signal pad and the impedance signal pin 543 of the flexible circuit board are directly connected through solder. There is no second covering film 550 between the impedance signal pad and the impedance signal pin 543 of the flexible circuit board, and the second covering film 550 does not cover the impedance signal pin. The impedance matching pad on the circuit board and the impedance signal pin Through the second solder connection, there are no stubs generated by the second covering film 550 at the second solder connection, which is beneficial to reducing the noise impact caused by the stubs.
  • the second cover film 550 does not cover the impedance signal pin, so only a smaller stub appears on the left side of the second via. Compared with FIG. 10 , the stump between the impedance signal pad 303 and the impedance signal pin 543 of the flexible circuit board is smaller than the stump between the non-impedance signal pad 301 and the non-impedance signal pin 542 .
  • the arrow in Figure 12 shows a schematic diagram of the impedance matching signal flow between the circuit board and the flexible circuit board.
  • the impedance matching signal passes from the impedance signal pad 303 of the circuit board through the first solder 3031 to the flexible circuit board.
  • the impedance signal pin 543 is transmitted to the TOP layer 520 through the second via hole, only a small unavoidable third stump 3032 appears on the left side of the second via hole, as shown in Figure 12 Dotted line part, thereby improving signal transmission performance.
  • the ground pins are arranged on both sides of the impedance signal pin to provide a return ground for signals in the impedance signal pin.
  • the present disclosure discloses an optical module, which includes: a circuit board provided with a first signal pad and a second signal pad.
  • One end of the flexible circuit board is connected to the circuit board and includes: a second conductive layer located below the first conductive layer and provided with a first signal pin and a second signal pin; the first signal pin and the first signal pin are soldered
  • the pads are connected through the first solder; the second covering film is attached to the lower surface of the second conductive layer, and the second covering film does not cover the first signal pin and the first signal pad.
  • the second signal pin and the second signal pad are connected through the second solder, and the second signal pin and the second signal pad cover part of the second cover film.
  • the first signal pad and the first signal pin There is no covering film between them, which avoids stumps caused by the covering film covering the first signal pad and the first signal pin, which is beneficial to reducing signal noise and improving Signal stability.
  • the second covering film does not cover the first signal pin, the first signal pad on the circuit board and the first signal pin are connected through the first solder, and there is no stub caused by the second covering film at the first solder connection. It is helpful to reduce the noise impact caused by stumps.
  • the solder is connected to the gold fingers and toes of the flexible circuit board, and the stress is concentrated on the edge of the second covering film, located at the connection between the second covering film and the gold fingers and toes.
  • the flexible circuit board 600 includes a top surface 601, a bottom surface 603, and a first insulating dielectric layer 602 disposed between the top surface 601 and the bottom surface 603.
  • the first insulating dielectric layer 602 is provided with metal vias therethrough.
  • the circuit board 105 includes a top surface 1051, a bottom surface 1053 and a second insulating dielectric layer 1052 located between the top surface 1051 and the bottom surface 1053; the flexible circuit board 600 and the circuit board 105 are electrically connected through solder 604, Specifically, the flexible circuit board 600 and the corresponding pads of the circuit board 105 are welded together through solder 604; the top surface 1051 of the circuit board 105 is a signal transmission layer, and the electrical signal is transmitted from the top surface 1051 of the circuit board 105 to the flexible circuit board 604 through the solder 604.
  • the bottom surface of the circuit board 600 is then transmitted to the top surface 601 of the flexible circuit board 600 through the metal via hole, and then transmitted to the light emitting component 400 through the high-frequency signal line on the surface of the flexible circuit board 600.
  • the laser in the light emitting component 400 After receiving the electrical signal, the electrical signal is converted into an optical signal and transmitted to the outside of the optical module.
  • the top surface of the flexible circuit board 600 is provided with a laser positive signal pad 610 and a first high-frequency signal pad 620.
  • a first high-frequency signal line 630 is connected between the laser positive signal pad 610 and the first high-frequency signal pad 620.
  • the top surface of the flexible circuit board 600 is provided with a laser negative signal pad 640 and a second high-frequency signal pad 660.
  • the second high-frequency signal pad 660 and the corresponding high-frequency signal pad on the bottom surface of the flexible circuit board 600 are electrically connected through metal via holes. connected, and then electrically connected to the corresponding high-frequency signal pad on the top surface of the circuit board.
  • a second high-frequency signal line 650 is connected between the laser negative signal pad 640 and the second high-frequency signal pad 660; where if the first high-frequency When the width of the frequency signal line 630 directly transitions to the first high-frequency signal pad 620, or when the width of the second high-frequency signal line 650 directly transitions to the second high-frequency signal pad 660, due to the distortion of the bottom surface of the flexible circuit board 600 The ground layer 690 cannot be connected to the signal pads on the bottom surface, so the first high-frequency signal line 630 and the second high-frequency signal line 650 will be suspended in the corresponding areas of the bottom surface.
  • the impedance continuity of the flexible board will directly affect the signal integrity of the entire link and even the entire optical module. Therefore, the optimized design of the impedance continuity of the flexible board is very important.
  • Figure 14 is a surface structure diagram of a flexible circuit board according to some embodiments
  • Figure 15 is a surface structure of a flexible circuit board according to some embodiments.
  • Figure 16 is another surface structure diagram of a flexible circuit board according to some embodiments.
  • Figures 14 and 15 are schematic structural diagrams of the top surface of the flexible circuit board 600.
  • the top surface of the flexible circuit board 600 is provided with a laser positive signal pad 610, a laser negative signal pad 640, a first high frequency Signal pad 620, second high-frequency signal pad 660, a first high-frequency signal line 630 is provided between the laser positive signal pad 610 and the first high-frequency signal pad 620, and a first high-frequency signal line 630 is provided between the laser negative signal pad 640 and the first high-frequency signal pad 620.
  • a second high-frequency signal line 650 is provided between the second high-frequency signal pads 660.
  • a first transition region 670 is provided between the first high-frequency signal line 630 and the first high-frequency signal pad 620.
  • a second transition region 680 is provided between the high-frequency signal line 650 and the second high-frequency signal pad 660.
  • the impedance at the first transition region 670 and the second transition region 680 is relative to the corresponding high-frequency signal line and the high-frequency signal bonding pad. There will be no large impedance mutation on the pad, which can increase the impedance continuity between the corresponding high-frequency signal line and the corresponding high-frequency signal pad.
  • Figure 16 is a schematic diagram of the bottom surface structure of the flexible circuit board 600.
  • the ground pin on the tube base passes through the ground through hole 693.
  • One end of the ground through hole 693 is connected to the ground plane, and then the tube base is electrically connected to the ground plane through the ground pin; the ground plane is
  • the ground layer 690 in FIG. 16 is electrically connected to the ground pad 691 and the ground pad 692, and then the ground pad 691 and the ground pad 692 are electrically connected to the ground on the circuit board 105.
  • the first transition area 670 includes a first connection area 671 and a second connection area 672
  • the second transition area 680 includes a third connection area 681 and a fourth connection area 682; wherein, the first high frequency
  • the signal line 630, the first connection area 671, and the second connection area 672 are connected to the first high-frequency signal pad 620 in sequence.
  • the width of the first connection area 671 close to the first high-frequency signal line 630 is smaller than the first high-frequency signal pad.
  • the width near the end of the second connection area 672 is greater than the width of the first high-frequency signal pad 620, and the width of the second connection area 672 is greater than the width of the first high-frequency signal pad 620, where the width direction refers to the The length direction of the first high-frequency signal line 630 is perpendicular to the direction; the second connection area 672 is designed to be widened, thereby increasing the width of the first transition area 670 so that the first high-frequency signal line 630 and the first high-frequency signal line 630 are welded together.
  • the first transition area 670 of the present disclosure also includes a first connection area 671 , and the first connection area 671 is close to the first high-frequency signal line 630
  • the width of the side is consistent with the width of the first high-frequency signal line 630
  • the width of the side of the first connection area 671 close to the first high-frequency signal pad 620 is consistent with the width of the second connection area 672 , so that the first The high-frequency signal line 630 and the first high-frequency signal pad 620 make a gentle transition through the first connection area 671 and the second connection area 672 in order to realize the transition from the first high-frequency signal line
  • the width gradually develops to avoid large sudden changes in impedance and ensure impedance continuity.
  • the first connection area 671 is in the shape of a right-angled trapezoid
  • the second connection area 672 is in the shape of a rectangle
  • the first connection area 671 and the second connection area 672 are metal layers, such as copper layers. .
  • the second transition area 680 includes a third connection area 681 and a fourth connection area 682.
  • the second high-frequency signal line 650, the third connection area 681, the fourth connection area 682, and the second high-frequency signal pad 660 are connected in sequence.
  • the width of the side of the third connection area 681 close to the second high-frequency signal line 650 is consistent with the width of the second high-frequency signal line 650
  • the width of the side of the third connection area 681 close to the second high-frequency signal pad 660 is consistent with the width of the side of the third connection area 681 close to the second high-frequency signal line 650 .
  • the width of the second high-frequency signal pad 660 remains consistent, and the width of the second high-frequency signal pad 660 is larger than the width of the second high-frequency signal pad 660; further, the fourth connection area 682 is designed to be widened, thereby increasing the The width of the second transition region 680 increases the capacitance per unit length between the second high-frequency signal line 650 and the second high-frequency signal pad 660, thereby reducing the size of the second high-frequency signal line 650 and the second high-frequency signal pad.
  • the impedance at the 660 connection optimizes the impedance continuity between the second high-frequency signal line 650 and the second high-frequency signal pad 660; and the third connection area 681 can further ensure that the second high-frequency signal line 650 and the fourth
  • the impedance continuity of the connection area 682 further increases the impedance continuity with the second high-frequency signal pad 660, so that the second high-frequency signal line 650 and the second high-frequency signal pad 660 pass through the third connection area 681 in sequence.
  • the fourth connection area 682 makes a gentle transition to achieve a gradual width development from the second high-frequency signal line to the second high-frequency signal pad, avoiding large sudden changes in impedance and ensuring impedance continuity. As can be seen from FIG.
  • the third connection region 681 is in the shape of an isosceles trapezoid
  • the fourth connection region 682 is in the shape of a rectangle
  • the third connection region 681 and the fourth connection region 682 are metal layers, such as copper. layer.
  • the widths of the second connection area 672 and the fourth connection area 682 are respectively increased by 4 mil than the first high-frequency signal pad 620 and the second high-frequency signal pad 660. Specifically, the widths of the left and right sides can be increased by 2 mil.
  • the shapes of the first connection area 671 and the third connection area 681 are approximately trapezoidal; It can be understood that the embodiment of the present disclosure only takes the first connection area 671 and the third connection area 681 as rectangles as an example for description; the second connection area
  • the shape of 672 and the fourth connection area 682 can be a regular shape such as a rectangle, a trapezoid, a circle, or an irregular shape such as a butterfly shape, and the widened size, such as 4mil, 6mil, etc., can be chosen arbitrarily within the allowable range of the process.
  • Both ends of the second connection area 672 protrude symmetrically or asymmetrically relative to the first high-frequency signal pad in the width direction, and the width of the second connection area 672 is wider than the first high-frequency signal pad.
  • the pad width is 4 mil
  • the two ends of the second connection area 672 protrude from the first high-frequency signal pad by 0 and 4 mil, 1 and 3 mil, and 2 and 2 mil respectively.
  • the fourth connection area 682 is similarly arranged; preferably, the width direction of the second connection area 672 is symmetrically protruded relative to the first high-frequency signal pad, and the width direction of the fourth connection area 682 is symmetrically protruding relative to the second high-frequency signal pad.
  • Figure 17 is a schematic diagram 1 of the simulation results of the flexible circuit board according to some embodiments;
  • Figure 18 is a schematic diagram 2 of the simulation results of the flexible circuit board according to some embodiments;
  • Figure 17 specifically shows the connection between the high-frequency signal line and the high-frequency signal pad.
  • the impedance simulation results, Figure 18 specifically shows the reflection amplitude simulation results at the connection between the high-frequency signal line and the high-frequency signal pad;
  • the solutions corresponding to curve 1 and curve 2 in Figure 17 are the traditional solution and the disclosed solution respectively.
  • the traditional solution It refers to the direct connection between the high-frequency signal line and the high-frequency signal pad.
  • the disclosed solution refers to the transitional connection between the high-frequency signal line and the high-frequency signal pad through the first connection area and the second connection area.
  • the solutions corresponding to curve 1 and curve 2 in Figure 18 are the traditional solution and the disclosed solution respectively.
  • the traditional solution refers to the direct connection between the high-frequency signal line and the high-frequency signal pad, and the disclosed solution refers to the high-frequency signal pad.
  • the high-frequency signal line and the high-frequency signal pad are transitionally connected through the first connection area and the second connection area.
  • the impedance at the connection point of the traditional solution is 56.1625 ⁇ , and the impedance at the connection point of the disclosed solution is 54.5496 ⁇ ; the impedance at the connection point between the high-frequency signal line and the high-frequency signal pad of the disclosed solution is reduced.
  • the present disclosure increases impedance continuity between high-frequency signal lines and high-frequency signal pads.
  • the reflection amplitude corresponding to the frequency of 20GHz of the traditional solution is -13.8632dB
  • the reflection amplitude corresponding to the disclosed solution is -15.8888dB.

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Abstract

一种光模块（200）包括：电路板（105）设有第一信号焊盘；柔性电路板（600），一端与所述电路板（105）连接，包括第二导电层（540），设有第一信号引脚和接地导电区（544），第一信号引脚与第一信号焊盘通过第一焊锡（3031）连接；第二覆盖膜（550），贴附于第二导电层（540）的下表面，且第二覆盖膜（550）不覆盖第一信号引脚和第一信号焊盘。第二覆盖膜（550）覆盖部分的接地导电区（544）。

Description

一种光模块
相关申请的交叉引用
本公开要求在2022年03月31日提交中国专利局、申请号为202210343045.3的中国专利申请的优先权；要求在2022年06月21日提交中国专利局、申请号为202210709079.X的中国专利申请的优先权，其全部内容通过引用结合在本公开中。
技术领域
本公开涉及光通信技术领域，尤其涉及一种光模块。
背景技术
随着云计算、移动互联网、视频等新型业务和应用模式发展，光通信技术的发展进步变的愈加重要。而在光通信技术中，光模块是实现光电信号相互转换的工具，是光通信设备中的关键器件之一，并且随着光通信技术发展的需求光模块的传输速率不断提高。
发明内容
第一方面，本公开实施例提供一种光模块，包括：电路板，包括：第一信号焊盘；柔性电路板，一端与电路板连接，包括：第二导电层，设有第一信号引脚，与第一信号焊盘通过第一焊锡连接；接地导电区，位于第一信号引脚的一侧；第二覆盖膜，贴附于第二导电层的下表面；第二覆盖膜的边缘设置于第一信号引脚与接地导电区之间；第二覆盖膜不覆盖第一信号引脚，且第二覆盖膜不覆盖第一信号焊盘；第二覆盖膜覆盖接地导电区。
第二方面，本公开实施例还提供一种光模块，包括：电路板；光发射组件，与电路板电连接，用于将电信号转换为光信号；柔性电路板，电连接电路板和光发射组件，表面设有：第一高频信号线；第一高频信号焊盘；第一高频信号线和第一高频信号焊盘之间设有第一连接区域和第二连接区域，第一高频信号线、第一连接区域、第二连接区域和第一高频信号焊盘依次连接， 第一高频信号焊盘宽度大于第一高频信号线宽度，第一连接区域一端宽度与第一高频信号线宽度相同，另一端宽度与第二连接区域宽度相同，第二连接区域宽度大于第一高频信号焊盘宽度。
附图说明
为了更清楚地说明本公开中的技术方案，下面将对本公开一些实施例中所需要使用的附图作简单地介绍，显而易见地，下面描述中的附图仅仅是本公开的一些实施例的附图，对于本领域普通技术人员来讲，还可以根据这些附图获得其他的附图。此外，以下描述中的附图可以视作示意图，并非对本公开实施例所涉及的产品的实际尺寸、方法的实际流程、信号的实际时序等的限制。
图1为根据一些实施例的一种光通信系统的连接关系图；
图2为根据一些实施例的一种光网络终端的结构图；
图3为根据一些实施例的一种光模块的结构图；
图4为根据一些实施例的一种光模块的分解图；
图5为根据一些实施例的光模块内部结构示意图；
图6为根据一些实施例的光发射组件与柔性电路板连接示意图；
图7为根据一些实施例的柔性电路板剖面结构示意图；
图8为根据一些实施例的柔性电路板的Bottom面局部结构示意图；
图9为根据一些实施例的柔性电路板的Bottom面局部结构示意图二；
图10为根据一些实施例的电路板与柔性电路板连接的局部剖面示意图一；
图11为根据一些实施例的电路板与柔性电路板连接的局部剖面示意图二；
图12为根据一些实施例的电路板与柔性电路板连接的局部剖面示意图三；
图13为根据一些实施例的柔性电路板与电路板连接示意图；
图14为根据一些实施例的柔性电路板的一表面结构图；
图15为根据一些实施例的柔性电路板的一表面结构放大示意图；
图16为根据一些实施例的柔性电路板的另一表面结构图；
图17为根据一些实施例的柔性电路板的仿真结果示意图一；
图18为根据一些实施例的柔性电路板的仿真结果示意图二。
具体实施方式
下面将结合附图，对本公开一些实施例中的技术方案进行清楚、完整地描述，显然，所描述的实施例仅仅是本公开一部分实施例，而不是全部的实施例。基于本公开所提供的实施例，本领域普通技术人员所获得的所有其他实施例，都属于本公开保护的范围。
除非上下文另有要求，否则，在整个说明书和权利要求书中，术语“包括(comprise)”及其其他形式例如第三人称单数形式“包括(comprises)”和现在分词形式“包括(comprising)”被解释为开放、包含的意思，即为“包含，但不限于”。在说明书的描述中，术语“一些实施例(some embodiments)”或“示例(example)”旨在表明与该实施例或示例相关的特定特征、结构、材料或特性包括在本公开的至少一个实施例或示例中。上述术语的示意性表示不一定是指同一实施例或示例。此外，所述的特定特征、结构、材料或特点可以以任何适当方式包括在任何一个或多个实施例或示例中。
以下，术语“第一”、“第二”仅用于描述目的，而不能理解为指示或暗示相对重要性或者隐含指明所指示的技术特征的数量。由此，限定有“第一”、“第二”的特征可以明示或者隐含地包括一个或者更多个该特征。在本公开实施例的描述中，除非另有说明，“多个”的含义是两个或两个以上。
在描述一些实施例时，可能使用了“连接”及其衍伸的表达。例如，描述一些实施例时可能使用了术语“连接”以表明两个或两个以上部件彼此间有直接物理接触或电接触。
“A和/或B”，包括以下三种组合：仅A，仅B，及A和B的组合。
本文中“被配置为”的使用意味着开放和包容性的语言，其不排除被配置为执行额外任务或步骤的设备。
如本文所使用的那样，“大致”或“近似”包括所阐述的值以及处于特定值的可接受偏差范围内的平均值，其中所述可接受偏差范围如由本领域普通技术人员考虑到正在讨论的测量以及与特定量的测量相关的误差(即，测量系统的局限性)所确定。
光通信系统中，使用光信号携带待传输的信息，并使携带有信息的光信号通过光纤或光波导等信息传输设备传输至计算机等信息处理设备，以完成 信息的传输。由于光通过光纤或光波导传输时具有无源传输特性，因此可以实现低成本、低损耗的信息传输。此外，光纤或光波导等信息传输设备传输的信号是光信号，而计算机等信息处理设备能够识别和处理的信号是电信号，因此为了在光纤或光波导等信息传输设备与计算机等信息处理设备之间建立信息连接，需要实现电信号与光信号的相互转换。
光模块在光通信技术领域中实现上述光信号与电信号的相互转换功能。光模块包括光口和电口，光模块通过光口实现与光纤或光波导等信息传输设备的光通信，通过电口实现与光网络终端(例如，光猫)之间的电连接，电连接主要用于供电、I2C信号传输、数据信息传输以及接地等；光网络终端通过网线或无线保真技术(Wi-Fi)将电信号传输给计算机等信息处理设备。
图1为光通信系统的连接关系图。如图1所示，光通信系统包括远端服务器1000、本地信息处理设备2000、光网络终端100、光模块200、光纤101及网线103。
光纤101的一端连接远端服务器1000，另一端通过光模块200与光网络终端100连接。光纤本身可支持远距离信号传输，例如数千米(6千米至8千米)的信号传输，在此基础上如果使用中继器，则理论上可以实现无限距离传输。因此在通常的光通信系统中，远端服务器1000与光网络终端100之间的距离通常可达到数千米、数十千米或数百千米。
网线103的一端连接本地信息处理设备2000，另一端连接光网络终端100。本地信息处理设备2000可以为以下设备中的任一种或几种：路由器、交换机、计算机、手机、平板电脑、电视机等。
远端服务器1000与光网络终端100之间的物理距离大于本地信息处理设备2000与光网络终端100之间的物理距离。本地信息处理设备2000与远端服务器1000之间的连接由光纤101与网线103完成；而光纤101与网线103之间的连接由光模块200和光网络终端100完成。
光模块200包括光口和电口，光口被配置为接入光纤101，从而使得光模块200与光纤101建立双向的光信号连接；电口被配置为接入光网络终端100中，从而使得光模块200与光网络终端100建立双向的电信号连接。光模块200实现光信号与电信号的相互转换，从而使得光纤101与光网络终端100之 间建立信息连接。示例地，来自光纤101的光信号由光模块200转换为电信号后输入至光网络终端100中，来自光网络终端100的电信号由光模块200转换为光信号输入至光纤101中。由于光模块200是实现光信号与电信号相互转换的工具，不具有处理数据的功能，在上述光电转换过程中，信息并未发生变化。
光网络终端100包括大致呈长方体的壳体(housing)，以及设置在壳体上的光模块接口102和网线接口104。光模块接口102被配置为接入光模块200，从而使得光网络终端100与光模块200建立双向的电信号连接；网线接口104被配置为接入网线103，从而使得光网络终端100与网线103建立双向的电信号连接。光模块200与网线103之间通过光网络终端100建立连接。示例地，光网络终端100将来自光模块200的电信号传递给网线103，将来自网线103的电信号传递给光模块200，因此光网络终端100作为光模块200的上位机，可以监控光模块200的工作。光模块200的上位机除光网络终端100之外还可以包括光线路终端(Optical Line Terminal，OLT)等。
远端服务器1000通过光纤101、光模块200、光网络终端100及网线103，与本地信息处理设备2000之间建立双向的信号传递通道。
图2为光网络终端的结构图，为了清楚地显示光模块200与光网络终端100的连接关系，图2仅示出了光网络终端100的与光模块200相关的结构。如图2所示，光网络终端100还包括设置于壳体内的电路板105，设置在电路板105表面的笼子106，设置在笼子106上的散热器107，以及设置在笼子106内部的电连接器。电连接器被配置为接入光模块200的电口；散热器107具有增大散热面积的翅片等凸起部。
光模块200插入光网络终端100的笼子106中，由笼子106固定光模块200，光模块200产生的热量传导给笼子106，然后通过散热器107进行扩散。光模块200插入笼子106中后，光模块200的电口与笼子106内部的电连接器连接，从而光模块200与光网络终端100建议双向的电信号连接。此外，光模块200的光口与光纤101连接，从而使光模块200与光纤101建立双向的光信号连接。
图3为根据一些实施例的一种光模块的结构图，图4为根据一些实施例 的一种光模块的分解图。如图3和图4所示，光模块200包括壳体(shell)，设置于壳体内的电路板105及光收发组件400。
壳体包括上壳体201和下壳体202，上壳体201盖合在下壳体202上，以形成具有两个开口的上述壳体；壳体的外轮廓一般呈现方形体。
在本公开的一些实施例中，下壳体202包括底板2021以及位于底板2021两侧、与底板2021垂直设置的两个下侧板2022；上壳体201包括盖板2011，盖板2011盖合在下壳体202的两个下侧板2022上，以形成上述壳体。
在一些实施例中，下壳体202包括底板2021以及位于底板2021两侧、与底板2021垂直设置的两个下侧板2022；上壳体201包括盖板2011以及位于盖板2011两侧、与盖板2011垂直设置的两个上侧板，由两个上侧板与两个下侧板2022结合，以实现上壳体201盖合在下壳体202上。
两个开口204和205的连线所在的方向可以与光模块200的长度方向一致，也可以与光模块200的长度方向不一致。例如，开口204位于光模块200的端部(图3的右端)，开口205也位于光模块200的端部(图3的左端)。或者，开口204位于光模块200的端部，而开口205则位于光模块200的侧部。开口204为电口，电路板105的金手指从电口204伸出，插入上位机(例如，光网络终端100)中；开口205为光口，被配置为接入外部光纤101，以使外部光纤101连接光模块200内部的光收发组件400。
采用上壳体201、下壳体202结合的装配方式，便于将电路板105、光收发组件400等器件安装到壳体中，由上壳体201、下壳体202对这些器件形成封装保护。此外，在装配电路板105和光收发组件400等器件时，便于这些器件的定位部件、散热部件以及电磁屏蔽部件的部署，有利于自动化地实施生产。
在一些实施例中，上壳体201及下壳体202一般采用金属材料制成，利于实现电磁屏蔽以及散热。
在一些实施例中，光模块200还包括位于其壳体外部的解锁部件，解锁部件被配置为实现光模块200与上位机之间的固定连接，或解除光模块200与上位机之间的固定连接。
示例地，解锁部件位于下壳体202的两个下侧板2022的外壁上，具有与 上位机笼子(例如，光网络终端100的笼子106)匹配的卡合部件。当光模块200插入上位机的笼子里，由解锁部件的卡合部件将光模块200固定在上位机的笼子里；拉动解锁部件时，解锁部件的卡合部件随之移动，进而改变卡合部件与上位机的连接关系，以解除光模块200与上位机的卡合关系，从而可以将光模块200从上位机的笼子里抽出。
图5为本公开实施例提供的一种光模块的内部结构示意图。如图5所示，本实施例提供的光模块中，光收发组件300包括圆方管体310，圆方管体310上嵌设在圆方管体310上的光发射组件400和光接收组件500；光发射组件400和光接收组件500分别通过柔性电路板600电连接电路板105，使光发射组件400用于输出信号光以及光接收组件500用于接收来自光模块外部的信号光，实现光模块电光以及光电的转换；圆方管体310中通常设置有透镜组件，透镜组件用于改变光发射组件400输出信号光或外部光纤输入信号光的传播方向。柔性电路板600一端与光发射组件400或光接收组件500电连接，另一端与电路板105电连接，进而实现光发射组件400或光接收组件500与电路板105的电连接；具体地，柔性电路板600包括第一连接部和第二连接部，第一连接部与光发射组件400或光接收组件500电连接，第二连接部与电路板105电连接；第一连接部和第二连接部分别设有相应焊盘，通过焊盘实现第一连接部与光发射组件400或光接收组件500电连接，以及第二连接部与电路板105电连接；柔性电路板600内部设有第一绝缘介质层，第一绝缘介质层的顶表面和底表面之间设有金属过孔，电路板105内部设有第二绝缘介质层，以光发射端为例，电信号从电路板105的顶表面传输至柔性电路板600的底表面，然后经过金属过孔，传输至柔性电路板600的顶表面，然后通过柔性电路板600表面的高频信号线传输至光发射组件400，光发射组件400中的激光器在接收到电信号后，将电信号转换为光信号，并发射至光模块外部。
如图6所示，管座上设有若干管脚，包括激光器正极管脚、激光器负极管脚、低频信号管脚和接地管脚，相应地，在柔性电路板靠近管座的表面设有相应管脚通孔，包括激光器正极管脚通孔、激光器负极管脚通孔、低频信号管脚通孔和接地管脚通孔，激光器正极管脚穿过激光器正极管脚通孔，并 与激光器正极信号焊盘焊接连接；激光器负极管脚穿过激光器负极管脚通孔，并与激光器负极信号焊盘焊接连接；低频信号管脚穿过低频信号管脚通孔，并与低频信号焊盘焊接连接。进一步结合图14，在图14中，激光器正极信号焊盘为激光器正极信号焊盘610，激光器负极信号焊盘为激光器负极信号焊盘640；在图14中还包括接地通孔693，管座上的接地管脚穿过接地通孔693，接地通孔693一端连接地平面，进而管座通过接地管脚电连接地平面；地平面为图17中的接地层690，接地层690与接地焊盘691和接地焊盘692电连接，然后接地焊盘691和接地焊盘692电连接至电路板105上的地。电路板105包括电路走线、电子元件及芯片，通过电路走线将电子元件和芯片按照电路设计连接在一起，以实现供电、电信号传输及接地等功能。电子元件例如包括电容、电阻、三极管、金属氧化物半导体场效应管(Metal-Oxide-Semiconductor Field-Effect Transistor，MOSFET)。芯片例如包括微控制单元(Microcontroller Unit，MCU)、激光驱动芯片、限幅放大器(limiting amplifier)、时钟数据恢复(Clock and Data Recovery，CDR)芯片、电源管理芯片、数字信号处理(Digital Signal Processing，DSP)芯片。
电路板105一般为硬性电路板，硬性电路板由于其相对坚硬的材质，还可以实现承载作用，如硬性电路板可以平稳地承载上述电子元件和芯片；当光收发组件位于电路板上时，硬性电路板也可以提供平稳地承载；硬性电路板还可以插入上位机笼子中的电连接器中。
电路板105还包括形成在其端部表面的金手指，金手指由相互独立的多个引脚组成。电路板105插入笼子106中，由金手指与笼子106内的电连接器导通连接。金手指可以仅设置在电路板105一侧的表面(例如图4所示的上表面)，也可以设置在电路板105上下两侧的表面，以适应引脚数量需求大的场合。金手指被配置为与上位机建立电连接，以实现供电、接地、I2C信号传递、数据信号传递等。当然，部分光模块中也会使用柔性电路板。柔性电路板一般与硬性电路板配合使用，以作为硬性电路板的补充。当然，部分光模块中也会使用柔性电路板。柔性电路板一般与硬性电路板配合使用，以作为硬性电路板的补充。例如，硬性电路板与光收发组件之间可以采用柔性电路板连接。
光收发组件400包括光发射器件及光接收器件，光发射器件被配置为实现光信号的发射，光接收器件被配置为实现光信号的接收。示例地，光发射器件及光接收器件结合在一起，形成一体地光收发组件。
实现电路板与光发射器件和/或光接收器件的电连接，通常设有柔性电路板与电路板连接。柔性电路板的一端设有金手指，最上方一层金属层义为TOP层520，最下方一层金属层为Bottom层540，TOP层520与Bottom层540通过过孔实现电路连接。TOP层520的上方贴附第一覆盖膜510，Bottom层540的下方设置第二层覆盖膜550。柔性电路板的Bottom层540与电路板上相应焊盘通过焊锡连接。
柔性电路板的金手指处设有接地引脚和信号线引脚，其中信号线引脚包括阻抗信号引脚和非阻抗信号引脚，阻抗信号引脚为有阻抗匹配要求的信号线连接的信号引脚，如激光芯片的驱动信号、跨阻放大芯片的驱动信号。阻抗匹配信号线需要匹配阻抗，用来减少信号噪声，提高通信稳定程度。
柔性电路板包括：第一导电层，与光发射器件和/或光接收器件连接；第二导电层，位于第一导电层的下方，设有第一信号引脚，与第一信号焊盘连接；第二覆盖膜，贴附于第二导电层的下表面。第一导电层与第二导电层之间设置隔离层530是柔性电路板的基材。第二覆盖膜不覆盖第一信号引脚，且第二覆盖膜不覆盖电路板上的第一信号焊盘。
在本公开的一些实施例中，第一导电层与第二导电层之间还可设置一层或多层中间导电层，第一导电层与第二导电层、第一导电层与中间导电层、第二导电层与中间导电层之间通过过孔实现电连接。
图7为本公开提供的柔性电路板的剖面结构示意图。本公开提供的实施例中，柔性电路板的结构示意图如图7中所示，包括至少两个金属层，最上方一层金属层即第一导电层为TOP层520，最下方一层金属层即第二导电层层为Bottom层540，TOP层520与Bottom层540之间设置一层隔离层530。在TOP层520的上表面覆盖第一覆盖膜510，在Bottom层540的下表面设置第二覆盖膜550。
图8为本公开提供的柔性电路板的Bottom面局部结构示意图。如图8中所示，柔性电路板的一端设有金手指，包括接地引脚541、非阻抗信号引脚 542和阻抗信号引脚543。接地引脚541、非阻抗信号引脚542和阻抗信号引脚543靠近柔性电路板端部的一端平齐设置，另一端不平齐。本公开中将图8中所示金手指的左侧称为第一端，右侧称为第二端。
即接地引脚541、非阻抗信号引脚542和阻抗信号引脚543的第二端平齐设置，第一端不平齐。
接地引脚541的另一端与接地导电区544连接。阻抗信号引脚543设有第一过孔5431，与阻抗匹配信号线连接，柔性电路板的阻抗匹配信号线设置于TOP层520。非阻抗信号引脚542设有第二过孔5421，与非阻抗匹配信号线连接。Bottom层540的表面设置第二覆盖膜550，覆盖Bottom层的部分区域。在本公开实施例中，阻抗匹配信号线与非阻抗匹配信号线设置于TOP层520。
接地导电区544的宽度大于接地引脚541的宽度。
为减少信号噪声，第二覆盖膜550不覆盖阻抗信号引脚543，且不覆盖第一过孔5431。在本公开中，第二覆盖膜550不覆盖阻抗信号引脚，电路板上的阻抗匹配焊盘与阻抗信号引脚通过第一焊锡连接，第一焊锡连接处不存在由第二覆盖膜550引起的残桩，有利于减少残桩带来的噪声影响。
为了增强柔性电路板上信号引脚与柔性电路板的连接应力，避免信号引脚受力后从柔性板脱落而造成断路，第二覆盖膜550覆盖部分的非阻抗信号引脚，增加了非阻抗信号引脚与柔性电路板之间的连接面积，增强了非阻抗信号引脚与柔性电路板之间的连接应力，可有效避免信号引脚受力后从柔性板脱落。
焊锡与柔性电路板的金手指引脚连接，应力集中在第二覆盖膜550的边缘，位于第二覆盖膜550与金手指引脚的连接处。非阻抗信号引脚542和接地引脚541第一端被第二覆盖膜550压住，阻抗信号引脚543远离应力集中点，从而避免了柔性电路板上的所有信号引脚的脱落。
第二覆盖膜550覆盖部分接地引脚541，接地引脚541裸露部分通过第三焊锡与电路板焊接。接地导电区具有较大的延展面积，第二覆盖膜550完全覆盖接地导电区、接地信号线，并部分覆盖接地引脚541。第二覆盖膜550覆盖部分非阻抗信号引脚542，且不覆盖第二过孔5421。如此，非阻抗信号引 脚542与第二覆盖膜550之间形成第一残桩，第二覆盖膜550与第二信号焊盘之间形成第二残桩，非阻抗信号在由电路板传递至柔性电路板上时，在第一残桩和第二残桩处形成开路信号流，产生信号噪声。而，第二覆盖膜550覆盖部分非阻抗信号引脚542，增强了非阻抗信号引脚542与柔性电路板隔离层530的连接应力。非阻抗信号引脚542与第二信号焊盘之间通过第二焊锡连接。
第二覆盖膜550不覆盖阻抗信号引脚543，且不覆盖第一过孔5431。在本公开中，非阻抗信号引脚542与电路板上第二信号焊盘之间设有第二覆盖膜550，非阻抗信号在由电路板传递至柔性电路板上时，在第一残桩和第二残桩处形成开路信号流，产生信号噪声。而第二覆盖膜550不覆盖阻抗信号引脚，电路板上的阻抗匹配焊盘与阻抗信号引脚通过第一焊锡连接，第一焊锡连接处不存在由第二覆盖膜550引起的残桩，有利于减少残桩带来的噪声影响。
在本公开中阻抗信号引脚为第一信号引脚，非阻抗信号引脚为第二信号引脚，接地引脚为第三信号引脚。阻抗信号焊盘为第一信号焊盘，非阻抗信号焊盘为第二信号焊盘，接地焊盘为第三信号焊盘。
板厂在贴合柔性电路板覆盖膜的最小公差为±i，焊盘上的渗锡孔孔环长度最小为j，设计焊盘长度必须保证孔环的完整，不能破环，板厂制程能力i大于j。
按照上述板厂的极限量产能力设计柔性电路板，最大程度地优化阻抗线信号的传输性能。一般情况下，第二覆盖膜的边缘压非阻抗信号引脚最小长度为i，第二覆盖膜的边缘压接地引脚最小长度为i，第二覆盖膜的边缘到第一过孔内壁边最短距离为i，这样在贴合公差范围内，第二覆盖膜即能压住非阻抗信号引脚、接地引脚(可防止独立引脚受外界的拉力而引脚脱落的风险)，同时也压住了接地导电区，防止焊接柔性印刷电路板(Flexible Printed Circuit board，FPC)金手指时露地铜而造成连焊；又防止第二覆盖膜盖住第一过孔影响焊盘渗锡。接地导电区按照板厂蚀刻线路能力距离手指焊盘做最小间距，来保证参考地的完整。
图9为本公开提供的柔性电路板的Bottom面局部结构示意图二。如图9 中所示，在本公开的一些实施例中，以靠近第二覆盖膜550的过孔内壁为基准，阻抗信号引脚543的第一端到距离第一过孔的孔内壁间距为第二间距b(保证过孔孔环的完整性，不能破孔)。第二覆盖膜550边缘与阻抗信号引脚543的边缘的距离为第一间距a，接地导电区边缘与第二覆盖膜550边缘的间距为第三间距c，以保证在覆盖膜贴合公差范围内即不压阻抗信号引脚，也能压住接地导电区防止连焊，从而只在阻抗匹配信号线上形成一个很短的不可避免的残桩。
对于非阻抗信号线引脚可设置为第二覆盖膜550覆盖非阻抗信号引脚542长度为第四间距e，即，第二覆盖膜550覆盖非阻抗信号引脚542，且第二覆盖膜550的边缘与非阻抗信号线边缘距离为e。上锡后应力集中在覆盖膜的边界，阻抗信号引脚远离了应力集中点，从而避免了FPC Bottom面阻抗信号引脚的脱落。
在本公开提供的实施例中，第一间距a与第三间距c的数值可以相同，也可不同。第一间距a与第四间距e的数值可以相同，也可不同。第四间距e与第三间距c的数值可以相同，也可不同。
通常，为方便制备，第二覆盖膜550的边缘平齐设置，即第二覆盖膜550的边缘与金手指端部边缘平行设置。如图9中所示的，第二覆盖膜550的右侧边缘与金手指的右端边缘平行设置。第一间距a、第三间距c与第四间距e的数值相同。
以下为本公开的一种柔性电路板示例，第一间距a等于第三间距c，且第三间距c小于第四间距e。
因此，接地导电区与阻抗信号引脚之间的距离应大于或等于2i；第二覆盖膜550边缘与阻抗信号引脚543的边缘的距离大于或等于贴合柔性电路板覆盖膜的最小公差i；接地导电区边缘与第二覆盖膜550边缘的间距大于或等于贴合柔性电路板覆盖膜的最小公差i。确保在贴合公差范围内，第二覆盖膜既能压住非阻抗信号引脚、接地引脚(可防止独立引脚受外界的拉力而引脚脱落的风险)，同时也压住了接地导电区，防止焊接FPC金手指时露地铜而造成连焊；又防止第二覆盖膜盖住第一过孔影响焊盘渗锡。接地导电区按照板厂蚀刻线路能力距离手指焊盘做最小间距，来保证参考地的完整。
第二覆盖膜的边缘与所述第一信号引脚的边缘的距离，等于第二覆盖膜的边缘与接地导电区边缘的距离，且接地导电区边缘与第一信号引脚的边缘的距离大于或等于覆盖膜的制程公差的二倍。第二覆盖膜的边缘位于接地导电区边缘与第一信号引脚边缘的中心位置，避免第二覆盖膜覆盖阻抗信号引脚，或导致接地导电区暴露。
第一过孔的内壁与第一信号引脚的第一端的距离不为零，避免第一过孔破损，影响第一导电层向第二导电层渗锡。
第二覆盖膜的边缘与第一信号引脚的边缘的距离，大于第一过孔的内壁与第一信号引脚的第一端的距离。
在本公开提供的一些实施例中，接地引脚541设置于阻抗信号引脚543与非阻抗信号引脚542之间。为与本公开提供的柔性电路板相匹配，本公开提供的电路板设有非阻抗信号焊盘、阻抗信号焊盘和接地焊盘。非阻抗信号焊盘与非阻抗信号引脚通过第二焊锡连接，阻抗信号引脚与阻抗信号焊盘通过第一焊锡连接，接地焊盘与接地引脚通过第三焊锡连接。
图10为本公开实施例提供的电路板与柔性电路板连接的局部剖面示意图一；图11为本公开实施例提供的电路板与柔性电路板连接的局部剖面示意图二；图12为本公开实施例提供的电路板与柔性电路板连接的局部剖面示意图三。其中，图10为电路板的阻抗信号焊盘与柔性电路板的非阻抗信号引脚连接示意图，如图10中所示，电路板的非阻抗信号焊盘与柔性电路板的非阻抗信号引脚542之间设有第二覆盖膜550，第二覆盖膜550的上下结构处出现两个残桩。图10中箭头所示为电路板与柔性电路板之间非阻抗匹配信号流通示意图，如图10中所示，非阻抗信号引脚542与第二覆盖膜550之间形成第一残桩3013(虚线部分)，第二覆盖膜550与第二信号焊盘之间形成第二残桩3012(虚线部分)，非阻抗信号在由电路板传递至柔性电路板上时，在第一残桩和第二残桩处形成开路信号流，产生信号噪声。非阻抗匹配信号由电路板的非阻抗信号焊盘301经第二焊锡3011，到柔性电路板的非阻抗信号引脚542时，在第二残桩引发信号噪声；非阻抗匹配信号由非阻抗信号引脚542经第一过孔5421传递至TOP层520的非阻抗信号线521时，在第二覆盖膜550覆盖下的非阻抗信号引脚542第一端与第一过孔5421之间形成的第一残桩， 引发信号噪声。
图11为电路板的接地焊盘与柔性电路板的接地引脚连接示意图，如图11中所示，电路板的接地焊盘302与柔性电路板的接地引脚541之间局部设有第二覆盖膜550，电路板的接地焊盘302与柔性电路板的接地引脚541之间通过第三焊锡3021连接。
图12为电路板的阻抗信号焊盘与柔性电路板的阻抗信号引脚连接示意图，如图12中所示，阻抗信号焊盘与柔性电路板的阻抗信号引脚543之间直接通过焊锡连接，阻抗信号焊盘与柔性电路板的阻抗信号引脚543之间不存在第二覆盖膜550，而第二覆盖膜550不覆盖阻抗信号引脚，电路板上的阻抗匹配焊盘与阻抗信号引脚通过第二焊锡连接，第二焊锡连接处不存在由第二覆盖膜550产生的残桩，有利于减少残桩带来的噪声影响。第二覆盖膜550不覆盖阻抗信号引脚，因此仅在第二过孔的左侧出现一个较小的残桩。与图10中相比，阻抗信号焊盘303与柔性电路板的阻抗信号引脚543之间的残桩，比非阻抗信号焊盘301与非阻抗信号引脚542之间的残桩小。
图12中箭头所示为电路板与柔性电路板之间阻抗匹配信号流通示意图，如图12中所示，阻抗匹配信号由电路板的阻抗信号焊盘303经第一焊锡3031，到柔性电路板的阻抗信号引脚543，再经第二过孔传递至TOP层520时，仅在第二过孔的左侧出现一个很小的不可避免的第三残桩3032，如12图中所示的虚线部分，从而提高信号传输性能。
接地引脚设置于阻抗信号引脚的两侧，为阻抗信号引脚内的信号提供回流地。
本公开公开了一种光模块，包括：电路板，设有第一信号焊盘和第二信号焊盘。柔性电路板一端与所述电路板连接，包括：第二导电层，位于第一导电层的下方，设有第一信号引脚和第二信号引脚；第一信号引脚与第一信号焊盘通过第一焊锡连接；第二覆盖膜，贴附于第二导电层的下表面，第二覆盖膜不覆盖第一信号引脚和第一信号焊盘。第二信号引脚与第二信号焊盘通过第二焊锡连接，第二覆盖膜覆盖部分的第二信号引脚和第二信号焊盘在本公开中第一信号焊盘与第一信号引脚之间不存在覆盖膜，避免了因覆盖膜覆盖第一信号焊盘和第一信号引脚而造成残桩，有利于减少信号噪声，提高 信号稳定程度。第二覆盖膜不覆盖第一信号引脚，电路板上的第一信号焊盘与第一信号引脚通过第一焊锡连接，第一焊锡连接处不存在由第二覆盖膜引起的残桩，有利于减少残桩带来的噪声影响。焊锡与柔性电路板的金手指引脚连接，应力集中在第二覆盖膜的边缘，位于第二覆盖膜与金手指引脚的连接处。第二信号引脚和接地引脚541第一端被第二覆盖膜压住，第一信号引脚远离应力集中点，从而避免了FPC Bottom面的所有信号引脚的脱落。如图13所示，柔性电路板600包括顶表面601、底表面603及设于顶表面601和底表面603之间的第一绝缘介质层602，第一绝缘介质层602贯穿设有金属过孔；电路板105包括顶表面1051、底表面1053及设于顶表面1051和底表面1053之间的第二绝缘介质层1052；柔性电路板600和电路板105之间通过焊锡604焊接实现电连接，具体是柔性电路板600和电路板105对应焊盘之间通过焊锡604焊接在一起；电路板105的顶表面1051为信号传输层，电信号从电路板105的顶表面1051通过焊锡604传输至柔性电路板600的底表面，然后经过金属过孔，传输至柔性电路板600的顶表面601，然后通过柔性电路板600表面的高频信号线传输至光发射组件400，光发射组件400中的激光器在接收到电信号后，将电信号转换为光信号，并发射至光模块外部。
柔性电路板600顶表面设有激光器正极信号焊盘610和第一高频信号焊盘620，激光器正极信号焊盘610和第一高频信号焊盘620之间连接有第一高频信号线630，柔性电路板600顶表面设有激光器负极信号焊盘640和第二高频信号焊盘660，第二高频信号焊盘660与柔性电路板600底面相应高频信号焊盘通过金属过孔电连接，然后与电路板顶面的相应高频信号焊盘电连接，激光器负极信号焊盘640和第二高频信号焊盘660之间连接有第二高频信号线650；其中如果第一高频信号线630的宽度直接过渡至第一高频信号焊盘620时，或者第二高频信号线650的宽度直接过渡至第二高频信号焊盘660时，由于柔性电路板600底表面的接地层690与底表面的信号焊盘不能相连接，因此会导致第一高频信号线630和第二高频信号线650在底表面对应的区域处存在悬空，该悬空会造成第一高频信号线630和第二高频信号线650阻抗突变，会出现明显升高，导致出现严重的阻抗不连续点，造成较大的信号反射，影响信号完整性及高频性能。
柔性板的阻抗连续性直接会影响整个链路乃至光模块整体的信号完整性，因此对于柔性板阻抗连续性的优化设计非常重要。
下面结合图14、图15及图16对本公开提供的方案进行具体说明；图14为根据一些实施例的柔性电路板的一表面结构图；图15为根据一些实施例的柔性电路板的一表面结构放大示意图；图16为根据一些实施例的柔性电路板的另一表面结构图。
图14和图15为柔性电路板600顶表面结构示意图，如图14和图15所示，柔性电路板600顶表面设有激光器正极信号焊盘610、激光器负极信号焊盘640、第一高频信号焊盘620、第二高频信号焊盘660，在激光器正极信号焊盘610和第一高频信号焊盘620之间设有第一高频信号线630，在激光器负极信号焊盘640和第二高频信号焊盘660之间设有第二高频信号线650，在第一高频信号线630和第一高频信号焊盘620之间设有第一过渡区域670，在第二高频信号线650和第二高频信号焊盘660之间设有第二过渡区域680，第一过渡区域670和第二过渡区域680处的阻抗相对于相应高频信号线和高频信号焊盘不会出现较大的阻抗突变，可增加相应高频信号线和相应高频信号焊盘之间的阻抗连续性。
图16为柔性电路板600底表面结构示意图，管座上的接地管脚穿过接地通孔693，接地通孔693一端连接地平面，进而管座通过接地管脚电连接地平面；地平面为图16中的接地层690，接地层690与接地焊盘691和接地焊盘692电连接，然后接地焊盘691和接地焊盘692电连接至电路板105上的地。
进一步，如图15所示，第一过渡区域670包括第一连接区域671和第二连接区域672，第二过渡区域680包括第三连接区域681和第四连接区域682；其中，第一高频信号线630、第一连接区域671、第二连接区域672与第一高频信号焊盘620依次连接，第一连接区域671靠近第一高频信号线630端的宽度小于第一高频信号焊盘620的宽度，靠近第二连接区域672端的宽度大于第一高频信号焊盘620的宽度，第二连接区域672的宽度大于第一高频信号焊盘620的宽度，其中宽度方向指的是与第一高频信号线630长度方向相垂直的方向；通过第二连接区域672作加宽设计，从而增加第一过渡区域670的宽度，使得第一高频信号线630和第一高频信号焊盘620之间单位长度电 容变大，从而降低第一高频信号线630与第一高频信号焊盘620连接处的阻抗，优化第一高频信号线和第一高频信号焊盘之间的阻抗连续性；为了保证第二连接区域672与第一高频信号线630之间的阻抗连续性，本公开第一过渡区域670还包括第一连接区域671，第一连接区域671靠近第一高频信号线630的侧边的宽度与第一高频信号线630的宽度保持一致，第一连接区域671靠近第一高频信号焊盘620的侧边的宽度与第二连接区域672的宽度保持一致，这样第一高频信号线630与第一高频信号焊盘620之间依次通过第一连接区域671、第二连接区域672进行平缓过渡，实现从第一高频信号线到第一高频信号焊盘间宽度渐变式发展，避免阻抗出现较大的突变，保证阻抗连续性。从图15中可以看出，第一连接区域671的形状为直角梯形状，第二连接区域672的形状为矩形形状，且第一连接区域671和第二连接区域672为金属层，如铜层。
第二过渡区域680包括第三连接区域681和第四连接区域682，第二高频信号线650、第三连接区域681、第四连接区域682、第二高频信号焊盘660依次连接，第三连接区域681靠近第二高频信号线650的侧边的宽度与第二高频信号线650的宽度保持一致，第三连接区域681靠近第二高频信号焊盘660的侧边的宽度与第二高频信号焊盘660的宽度保持一致，第二高频信号焊盘660的宽度比第二高频信号焊盘660的宽度大；进而通过第四连接区域682作加宽设计，从而增加第二过渡区域680的宽度，使得第二高频信号线650和第二高频信号焊盘660之间单位长度电容变大，从而降低第二高频信号线650和第二高频信号焊盘660连接处的阻抗，优化第二高频信号线650和第二高频信号焊盘660之间的阻抗连续性；且通过第三连接区域681可以进一步保证第二高频信号线650与第四连接区域682的阻抗连续性，进而增加与第二高频信号焊盘660的阻抗连续性，这样第二高频信号线650与第二高频信号焊盘660之间依次通过第三连接区域681、第四连接区域682进行平缓过渡，实现从第二高频信号线到第二高频信号焊盘间宽度渐变式发展，避免阻抗出现较大的突变，保证阻抗连续性。从图15中可以看出，第三连接区域681的形状为等腰梯形形状，第四连接区域682的形状为矩形形状，且第三连接区域681和第四连接区域682为金属层，如铜层。
进一步，本公开实施例中第二连接区域672和第四连接区域682的宽度分别比第一高频信号焊盘620和第二高频信号焊盘660增加4mil，具体可以左右两侧各增加2mil；第一连接区域671和第三连接区域681的形状近似梯形；可以理解的是，本公开实施例仅以第一连接区域671和第三连接区域681为矩形为例进行说明；第二连接区域672和第四连接区域682的形状可以是矩形、梯形、圆形等规则形状，也可以是蝶形等不规则形状，以及加宽的大小，如4mil，6mil等在工艺允许范围内的任意取值都应作为本公开的保护范围；第二连接区域672的两端宽度方向上相对于第一高频信号焊盘对称突出或者非对称突出，以第二连接区域672宽度比第一高频信号焊盘宽度大4mil为例，第二连接区域672的两端突出第一高频信号焊盘分别为0和4mil、1和3mil、2和2mil。第四连接区域682同样类似设置；其中优选第二连接区域672两端宽度方向上相对于第一高频信号焊盘对称突出，第四连接区域682两端宽度方向上相对于第二高频信号焊盘对称突出，此时第一高频信号线和第二高频信号线之间的耦合性能较好。图17为根据一些实施例的柔性电路板的仿真结果示意图一；图18为根据一些实施例的柔性电路板的仿真结果示意图二；图17具体为高频信号线与高频信号焊盘连接处的阻抗仿真结果，图18具体为高频信号线与高频信号焊盘连接处的反射幅度仿真结果；图17中的曲线1和曲线2对应的方案分别为传统方案和本公开方案，传统方案指的是高频信号线与高频信号焊盘之间直接进行连接，本公开方案指的是高频信号线与高频信号焊盘之间通过第一连接区域和第二连接区域进行过渡连接；图18中的曲线1和曲线2对应的方案分别为传统方案和本公开方案，传统方案指的是高频信号线与高频信号焊盘之间直接进行连接，本公开方案指的是高频信号线与高频信号焊盘之间通过第一连接区域和第二连接区域进行过渡连接。
从图17中可以看出，传统方案连接处阻抗为56.1625Ω，本公开方案连接处阻抗为54.5496Ω；本公开高频信号线与高频信号焊盘连接处的阻抗降低，相对于传统方案，本公开增加了高频信号线与高频信号焊盘之间的阻抗连续性。
从图18中可以看出，传统方案频率20GHz对应的反射幅度为-13.8632dB，本公开方案对应的反射幅度为-15.8888dB，数值绝对值越大表示性能越好，因 此本公开实施例提供的方案具有一定优势。
由于以上实施方式均是在其他方式之上引用结合进行说明，不同实施例之间均具有相同的部分，本说明书中各个实施例之间相同、相似的部分互相参见即可。在此不再详细阐述。
本领域技术人员在考虑说明书及实践本申请的公开后，将容易想到本申请的其他实施方案。本申请旨在涵盖本申请的任何变型、用途或者适应性变化，这些变型、用途或者适应性变化遵循本申请的一般性原理并包括本申请未公开的本技术领域中的公知常识或惯用技术手段。说明书和实施例仅被视为示例性的，本申请的真正范围和精神由权利要求的内容指出。以上所述，仅为本公开的具体实施方式，但本公开的保护范围并不局限于此，任何熟悉本技术领域的技术人员在本公开揭露的技术范围内，想到变化或替换，都应涵盖在本公开的保护范围之内。因此，本公开的保护范围应以所述权利要求的保护范围为准。

Claims (19)

  1. 一种光模块，包括：
    电路板，包括：第一信号焊盘；
    柔性电路板，一端与所述电路板连接，包括：
    第二导电层，设有第一信号引脚，与所述第一信号焊盘通过第一焊锡连接；
    接地导电区，位于所述第一信号引脚的一侧；
    第二覆盖膜，贴附于所述第二导电层的下表面；
    所述第二覆盖膜的边缘设置于所述第一信号引脚与所述接地导电区之间；
    所述第二覆盖膜不覆盖所述第一信号引脚，且所述第二覆盖膜不覆盖所述第一信号焊盘；
    所述第二覆盖膜覆盖所述接地导电区。
  2. 根据权利要求1所述的光模块，其中，所述电路板还设有第二信号引脚；
    所述电路板设有第二信号焊盘；
    与所述第二信号焊盘通过第二焊锡连接；
    所述第二覆盖膜覆盖部分的所述第二信号引脚，且所述第二覆盖膜覆盖部分的所述第二信号焊盘；
    其中所述第一信号引脚为阻抗信号引脚；所述第二信号引脚为非阻抗信号引脚。
  3. 根据权利要求2所述的光模块，其中，所述第二信号引脚的第二端与所述第一信号引脚的第二端平齐；所述第二信号引脚的第一端与所述第一信号引脚的第一端不平齐。
  4. 根据权利要求1所述的光模块，其中，所述第二焊锡的部分设置于所述第二覆盖膜与所述第二信号焊盘之间。
  5. 根据权利要求1所述的光模块，其中，所述柔性电路板包括：第一导电层，设置于所述第二导电层的上方；
    所述第一信号引脚设有第一过孔，与所述第一导电层连接；
    所述第一过孔的内壁与所述第一信号引脚的第一端的距离不为零。
  6. 根据权利要求2所述的光模块，其中，所述第二导电层还包括接地引 脚；
    所述接地引脚的第一端与所述接地导电区连接；
    第二覆盖膜覆盖部分所述接地引脚；
    所述接地引脚设置于所述第一信号引脚与所述第二信号引脚之间。
  7. 根据权利要求2所述的光模块，其中，所述第二覆盖膜的边缘与所述第一信号引脚的边缘的距离，大于所述第一过孔的内壁与所述第一信号引脚的第一端的距离。
  8. 根据权利要求2所述的光模块，其中，所述第二覆盖膜的边缘与所述第一信号引脚的边缘的距离，等于所述第二覆盖膜的边缘与所述接地导电区边缘的距离。
  9. 根据权利要求2所述的光模块，其中，所述接地导电区边缘与所述第一信号引脚的边缘的距离大于或等于所述覆盖膜的制程公差的二倍。
  10. 根据权利要求2所述的光模块，其中，还包括：光接收器件和/或光发射器件；
    所述第一信号引脚为阻抗信号引脚，与所述光接收器件和/或光发射器件中的阻抗匹配信号线连接；所述第二信号引脚为非阻抗信号引脚，与所述光接收器件和/或光发射器件的非阻抗匹配信号线连接。
  11. 一种光模块，包括：
    电路板；
    光发射组件，与所述电路板电连接，用于将电信号转换为光信号；
    柔性电路板，电连接所述电路板和光发射组件，表面设有：
    第一高频信号线；
    第一高频信号焊盘；
    所述第一高频信号线和所述第一高频信号焊盘之间设有第一连接区域和第二连接区域，所述第一高频信号线、所述第一连接区域、所述第二连接区域和所述第一高频信号焊盘依次连接，所述第一高频信号焊盘宽度大于所述第一高频信号线宽度，所述第一连接区域一端宽度与所述第一高频信号线宽度相同，另一端宽度与所述第二连接区域宽度相同，所述第二连接区域宽度大于所述第一高频信号焊盘宽度。
  12. 根据权利要求11所述的光模块，其中，所述第一连接区域靠近所述第一高频信号线端的宽度小于所述第一高频信号焊盘宽度，靠近所述第二连 接区域端的宽度大于所述第一高频信号焊盘宽度。
  13. 根据权利要求11所述的光模块，其中，所述第二连接区域两端宽度方向分别相对于所述第一高频信号焊盘对称突出。
  14. 根据权利要求11所述的光模块，其中，所述第一连接区域设为直角梯形状，所述第二连接区域设为矩形状；
    所述第一连接区域和所述第二连接区域均为金属层。
  15. 根据权利要求11所述的光模块，其中，所述第二连接区域的宽度比所述第一高速信号焊盘的宽度大4密耳或6密耳。
  16. 根据权利要求11所述的光模块，其中，所述柔性电路板表面设有：
    第二高频信号线；
    第二高频信号焊盘；
    所述第二高频信号线和所述第二高频信号焊盘之间设有第三连接区域和第四连接区域，所述第二高频信号线、所述第三连接区域、所述第四连接区域和所述第二高频信号焊盘依次连接，所述第二高频信号焊盘宽度大于所述第二高频信号线宽度，所述第三连接区域一端宽度与所述第二高频信号线宽度相同，另一端宽度与所述第四连接区域宽度相同，所述第四连接区域宽度大于所述第二高频信号焊盘宽度。
  17. 根据权利要求16所述的光模块，其中，所述第三连接区域靠近所述第二高频信号线端的宽度小于所述第二高频信号焊盘宽度，靠近所述第四连接区域端的宽度大于所述第二高频信号焊盘宽度。18、根据权利要求16所述的光模块，其中，所述第四连接区域两端宽度方向相对于所述第二高频信号焊盘对称突出。
  18. 根据权利要求17所述的光模块，其中，所述第三连接区域设为等腰梯形状，所述第四连接区域设为矩形状；
    所述第三连接区域和所述第四连接区域均为金属层。
  19. 根据权利要求11所述的光模块，其中，所述柔性电路板底表面与所述电路板顶表面通过锡焊电连接；
    所述柔性电路板顶表面相应焊盘和所述柔性电路板底表面相应焊盘之间设有金属过孔。
PCT/CN2023/072133 2022-03-31 2023-01-13 一种光模块 WO2023185216A1 (zh)

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