CN114879321B - Optical module - Google Patents

Abstract

The optical module comprises a circuit board, a light emitting assembly and a flexible circuit board; the flexible circuit board is provided with a first high-frequency signal wire and a first high-frequency signal pad, a first connecting area and a second connecting area are arranged between the first high-frequency signal wire and the first high-frequency signal pad, one end of the first connecting area has the same width as the first high-frequency signal wire, the other end has the same width as the second connecting area, and the width of the second connecting area is larger than that of the first high-frequency signal pad; because the second connection area is widened, the capacitance per unit length between the first high-frequency signal wire and the first high-frequency signal pad is increased, the impedance of the joint of the first high-frequency signal wire and the first high-frequency signal pad can be reduced, the impedance continuity between the first high-frequency signal wire and the second connection area can be ensured through the transition of the first connection area, and the signal integrity between the first high-frequency signal wire and the first high-frequency signal pad is further optimized.

Description

Optical module

Technical Field

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

Background

The optical module as a photoelectric conversion device includes a circuit board, a light emitting end, and a light receiving end, and in some structures, electrical connection of the circuit board with the light emitting end or the light receiving end is achieved through a flexible circuit board (FPC, flexible Printed Circuit).

In an optical module using a flexible circuit board, signal connection between an optical transmitting end or an optical receiving end and a circuit board is achieved through the flexible circuit board, so that impedance continuity of the flexible circuit board directly affects signal integrity of the entire channel.

Disclosure of Invention

The application provides an optical module for optimizing impedance continuity of a connection part of a high-frequency signal wire and a bonding pad on the surface of a flexible circuit board.

The application provides an optical module, including:

a circuit board;

the light emitting assembly is electrically connected with the circuit board and is used for converting the electric signal into an optical signal;

the flexible circuit board is electrically connected with the circuit board and the light emitting component, and the surface is provided with:

a first high-frequency signal line;

a first high frequency signal pad;

the high-frequency signal wire is characterized in that a first connecting area and a second connecting area are arranged between the first high-frequency signal wire and the first high-frequency signal bonding pad, the first high-frequency signal wire, the first connecting area, the second connecting area and the first high-frequency signal bonding pad are sequentially connected, the width of the first high-frequency signal bonding pad is larger than that of the first high-frequency signal wire, one end of the first connecting area is identical to that of the first high-frequency signal wire, the other end of the first connecting area is identical to that of the second connecting area, and the width of the second connecting area is larger than that of the first high-frequency signal bonding pad.

The optical module comprises a circuit board and an optical emission assembly, wherein the circuit board and the optical emission assembly are electrically connected through a flexible circuit board; the surface of the flexible circuit board is provided with a first high-frequency signal wire and a first high-frequency signal pad, and the impedance of the joint of the first high-frequency signal wire and the first high-frequency signal pad in the original design is higher; for this purpose, a first connection area and a second connection area are arranged between the first high-frequency signal wire and the first high-frequency signal pad, one end of the first connection area has the same width as the first high-frequency signal wire, the other end has the same width as the second connection area, and the second connection area has a width larger than that of the first high-frequency signal pad; because the width of the second connecting area is larger than that of the first high-frequency signal pad, the second connecting area is widened, so that the capacitance per unit length between the first high-frequency signal wire and the first high-frequency signal pad is increased, the impedance of the joint of the first high-frequency signal wire and the first high-frequency signal pad is reduced, and the impedance continuity between the first high-frequency signal wire and the first high-frequency signal pad is optimized; and the impedance continuity between the first high-frequency signal wire and the second connection area can be ensured through the transition of the first connection area, the gradual development of the width between the first high-frequency signal wire and the first high-frequency signal pad is realized, the impedance continuity between the first high-frequency signal wire and the first high-frequency signal pad is further optimized, the signal integrity is improved, and the high-frequency performance is optimized.

Drawings

In order to more clearly illustrate the technical solutions of the present disclosure, the drawings that need to be used in some embodiments of the present disclosure will be briefly described below, and it is apparent that the drawings in the following description are only drawings of some embodiments of the present disclosure, and other drawings may be obtained according to these drawings to those of ordinary skill in the art. Furthermore, the drawings in the following description may be regarded as schematic diagrams, not limiting the actual size of the products, the actual flow of the methods, the actual timing of the signals, etc. according to the embodiments of the present disclosure.

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

fig. 2 is a block diagram of an optical network terminal according to some embodiments;

FIG. 3 is a block diagram of an optical module according to some embodiments;

fig. 4 is an exploded view of a light module according to some embodiments;

FIG. 5 is a schematic diagram of an internal architecture of an optical module according to some embodiments;

FIG. 6 is a schematic diagram of a light emitting assembly connected to a flexible circuit board according to some embodiments;

FIG. 7 is a schematic diagram of a flexible circuit board-to-circuit board connection according to some embodiments;

FIG. 8 is a surface structure diagram of a flexible circuit board according to some embodiments;

FIG. 9 is an enlarged schematic view of a surface structure of a flexible circuit board according to some embodiments;

FIG. 10 is another surface structure diagram of a flexible circuit board according to some embodiments;

FIG. 11 is a schematic diagram of simulation results of a flexible circuit board according to some embodiments;

fig. 12 is a second schematic diagram of simulation results of a flexible circuit board according to some embodiments.

Detailed Description

The following description of the embodiments of the present disclosure will be made clearly and fully with reference to the accompanying drawings, in which it is evident that the embodiments described are only some, but not all, of the embodiments of the present disclosure. All other embodiments obtained by one of ordinary skill in the art based on the embodiments provided by the present disclosure are within the scope of the present disclosure.

Throughout the specification and claims, unless the context requires otherwise, the word "comprise" and its other forms such as the third person referring to the singular form "comprise" and the present word "comprising" are to be construed as open, inclusive meaning, i.e. as "comprising, but not limited to. In the description of the specification, the terms "one embodiment", "some embodiments", "exemplary embodiment", "example", "specific example", "some examples", "and the like are intended to indicate that a particular feature, structure, material, or characteristic associated with the embodiment or example is included in at least one embodiment or example of the present disclosure. The schematic representations of the above terms do not necessarily refer to the same embodiment or example. Furthermore, the particular features, structures, materials, or characteristics may be combined in any suitable manner in any one or more embodiments or examples.

The terms "first" and "second" are used below for descriptive purposes only and are not to be construed as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, a feature defining "a first" or "a second" may explicitly or implicitly include one or more such feature. In the description of the embodiments of the present disclosure, unless otherwise indicated, the meaning of "a plurality" is two or more.

In describing some embodiments, expressions of "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 in describing some embodiments to indicate that two or more elements are in direct physical or electrical contact. However, the term "coupled" or "communicatively coupled (communicatively coupled)" may also mean that two or more elements 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 to the disclosure herein.

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

The use of "adapted" or "configured to" herein is meant to be an open and inclusive language that does not exclude devices adapted or configured to perform additional tasks or steps.

As used herein, "about," "approximately" or "approximately" includes the stated values as well as average values within an acceptable deviation range of the particular values as determined by one of ordinary skill in the art in view of the measurement in question and the errors associated with the measurement of the particular quantity (i.e., limitations of the measurement system).

In the optical communication technology, light is used to carry information to be transmitted, and an optical signal carrying the information is transmitted to an information processing device such as a computer through an information transmission device such as an optical fiber or an optical waveguide, so as to complete the transmission of the information. Since the optical signal has a passive transmission characteristic when transmitted through an optical fiber or an optical waveguide, low-cost and low-loss information transmission can be realized. Further, since a signal transmitted by an information transmission device such as an optical fiber or an optical waveguide is an optical signal and a signal that can be recognized and processed by an information processing device such as a computer is an electrical signal, it is necessary to perform mutual conversion between the electrical signal and the optical signal in order to establish an information connection between the information transmission device such as an optical fiber or an optical waveguide and the information processing device such as a computer.

The optical module realizes the function of interconversion between the optical signal and the electric signal in the technical field of optical fiber communication. The optical module comprises an optical port and an electric port, the optical module realizes optical communication with information transmission equipment such as optical fibers or optical waveguides through the optical port, realizes electric connection with an optical network terminal (for example, optical cat) through the electric port, and is mainly used for realizing power supply, I2C signal transmission, data signal transmission, grounding and the like; the optical network terminal transmits the electric signal to information processing equipment such as a computer through a network cable or wireless fidelity (Wi-Fi).

Fig. 1 is a connection diagram of an optical communication system according to some embodiments. As shown in fig. 1, the optical communication system mainly 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. The optical fiber itself can support long-distance signal transmission, such as signal transmission of several kilometers (6-8 kilometers), on the basis of which, if a repeater is used, it is theoretically possible to realize ultra-long-distance transmission. Thus, in a typical optical communication system, the distance between the remote server 1000 and the optical network terminal 100 may typically reach several 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 apparatus 2000 may be any one or several of the following: routers, switches, computers, cell phones, tablet computers, televisions, 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 apparatus 2000 and the optical network terminal 100. The connection between the local information processing device 2000 and the remote server 1000 is completed by an optical fiber 101 and a network cable 103; and the connection between the optical fiber 101 and the network cable 103 is made 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 connect with the optical fiber 101 such that the optical module 200 establishes a bi-directional optical signal connection with the optical fiber 101; the electrical port is configured to be accessed into the optical network terminal 100 such that the optical module 200 establishes a bi-directional electrical signal connection with the optical network terminal 100. The optical module 200 performs 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, an optical signal from the optical fiber 101 is converted into an electrical signal by the optical module 200 and then input to the optical network terminal 100, and an electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module 200 and input to the optical fiber 101.

The optical network terminal 100 includes a substantially rectangular parallelepiped housing (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 such that the optical network terminal 100 establishes a bi-directional electrical signal connection with the network cable 103. A connection is established between the optical module 200 and the network cable 103 through the optical network terminal 100. By way of example, since the optical network terminal 100 transmits an electrical signal from the optical module 200 to the network cable 103 and transmits a signal from the network cable 103 to the optical module 200, the optical network terminal 100 can monitor the operation of the optical module 200 as a host computer of the optical module 200. The upper computer of the optical module 200 may include an optical line terminal (Optical Line Terminal, OLT) or the like in addition to the optical network terminal 100.

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.

Fig. 2 is a block diagram of an optical network terminal according to some embodiments, and fig. 2 only shows a structure of the optical network terminal 100 related to the optical module 200 in order to clearly show a connection relationship between the optical module 200 and the optical network terminal 100. As shown in fig. 2, the optical network terminal 100 further includes a PCB circuit board 105 disposed in the housing, a cage 106 disposed on a surface of the PCB circuit board 105, and an electrical connector disposed inside the cage 106. The electrical connector is configured to access an electrical port of the optical module 200; the heat sink 107 has a convex portion 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, the optical module 200 is fixed by the cage 106, and heat generated by the optical module 200 is transferred to the cage 106 and then diffused through the heat sink 107. After the optical module 200 is inserted into the cage 106, the electrical port of the optical module 200 is connected with an electrical connector inside the cage 106, so that the optical module 200 establishes a bi-directional 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 bi-directional electrical signal connection with the optical fiber 101.

Fig. 3 is a block diagram of an optical module according to some embodiments, and fig. 4 is an exploded view of an optical module according to some embodiments. As shown in fig. 3 and 4, the optical module 200 includes a housing, a circuit board 105 disposed in the housing, and an optical transceiver assembly.

The housing includes an upper housing 201 and a lower housing 202, the upper housing 201 being capped on the lower housing 202 to form the above-described housing having two openings 204 and 205; the outer contour of the housing generally presents a square shape.

In some embodiments of the present disclosure, the lower housing 202 includes a bottom plate and two lower side plates disposed at both sides of the bottom plate and perpendicular to the bottom plate; the upper case 201 includes a cover plate, and two upper side plates disposed at two sides of the cover plate and perpendicular to the cover plate, and two side walls are combined with the two side plates to realize that the upper case 201 is covered on the lower case 202.

The direction of the connection line of the two openings 204 and 205 may be identical to the length direction of the optical module 200 or not identical to the length direction of the optical module 200. Illustratively, opening 204 is located at the end of light module 200 (left end of fig. 3) and opening 205 is also located at the end of light module 200 (right end of fig. 3). Alternatively, the opening 204 is located at the end of the light module 200, while the opening 205 is located at the side of the light module 200. The opening 204 is an electrical opening, and the golden finger of the circuit board 105 extends out of the opening 204 and is inserted into an upper computer (such as the optical network terminal 100); the opening 205 is an optical port configured to be connected to the external optical fiber 101, so that the optical fiber 101 is connected to an optical transceiver module inside the optical module 200.

By adopting the assembly mode of combining the upper shell 201 and the lower shell 202, devices such as the circuit board 105, the optical transceiver component and the like are conveniently installed in the shell, and the upper shell 201 and the lower shell 202 can form packaging protection for the devices. In addition, when devices such as the circuit board 105 are assembled, the positioning component, the heat dissipation component and the electromagnetic shielding component of the devices are conveniently arranged, and the automatic implementation and production are facilitated.

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

In some embodiments, the optical module 200 further includes an unlocking member 203 located on an outer wall of the housing, where the unlocking member 203 is configured to achieve a fixed connection between the optical module 200 and the host computer, or to release the fixed connection between the optical module 200 and the host computer.

Illustratively, the unlocking member 203 is located on the outer walls of the two lower side plates of the lower housing 202, and includes a snap-in member that mates with the cage of the host computer (e.g., cage 106 of the optical network terminal 100). When the optical module 200 is inserted into the cage of the upper computer, the optical module 200 is fixed in the cage of the upper computer by the clamping component of the unlocking component 203; when the unlocking member 203 is pulled, the engaging member of the unlocking member 203 moves along with the unlocking member, so as to change the connection relationship between the engaging member and the host computer, so as to release the engagement relationship between the optical module 200 and the host computer, and thus the optical module 200 can be pulled out from the cage of the host computer.

The circuit board 105 includes circuit traces, electronic components, and chips, which are connected together by circuit traces according to a circuit design to perform functions such as power supply, electrical signal transmission, and grounding. The electronic components may include, for example, capacitors, resistors, transistors, metal-Oxide-Semiconductor Field-Effect Transistor (MOSFET). The chips may include, for example, a micro control unit (Microcontroller Unit, MCU), limiting amplifier (limiting amplifier), clock data recovery chip (Clock and Data Recovery, CDR), power management chip, digital signal processing (Digital Signal Processing, DSP) chip.

The circuit board 105 is generally a hard circuit board, and the hard circuit board can also realize a bearing function due to the relatively hard material, for example, the hard circuit board can stably bear chips; the hard circuit board can also be inserted into an electrical connector in the upper computer cage.

The circuit board 105 further includes a gold finger formed on an end surface thereof, the gold finger being composed of a plurality of pins independent of each other. The circuit board 105 is inserted into the cage 106 and is connected by a gold finger to an electrical connector in the cage 106. The golden finger may be disposed on a surface of only one side of the circuit board 105 (for example, an upper surface shown in fig. 4), or may be disposed on surfaces of both upper and lower sides of the circuit board 105, so as to adapt to a situation where the number of pins is large. The golden finger is configured to establish electrical connection with the upper computer to achieve power supply, grounding, I2C signal transmission, data signal transmission and the like. Of course, flexible circuit boards may also be used in some optical modules. The flexible circuit board is generally used in cooperation with the rigid circuit board to supplement the rigid circuit board.

Fig. 5 is a schematic diagram of an internal structure of an optical module according to an embodiment of the present application. As shown in fig. 5, in the optical module provided in this embodiment, the optical transceiver module 300 includes a circular square tube 310, and an optical transmitter module 400 and an optical receiver module 500 embedded on the circular square tube 310; the light emitting component 400 and the light receiving component 500 are respectively and electrically connected with the circuit board 105 through the flexible circuit board 600, so that the light emitting component 400 is used for outputting signal light and the light receiving component 500 is used for receiving signal light from the outside of the light module, and the photoelectric conversion of the light module is realized; a lens assembly is generally disposed in the circular square tube 310, and the lens assembly is used to change the propagation direction of the signal light output from the light emitting assembly 400 or the signal light input from the external optical fiber. One end of the flexible circuit board 600 is electrically connected with the light emitting component 400 or the light receiving component 500, and the other end is electrically connected with the circuit board 105, so that the light emitting component 400 or the light receiving component 500 is electrically connected with the circuit board 105; specifically, the flexible circuit board 600 includes a first connection part electrically connected to the light emitting assembly 400 or the light receiving assembly 500 and a second connection part electrically connected to the circuit board 105; the first connection part and the second connection part are respectively provided with corresponding bonding pads, and the first connection part is electrically connected with the light emitting assembly 400 or the light receiving assembly 500 through the bonding pads, and the second connection part is electrically connected with the circuit board 105; the flexible circuit board 600 is internally provided with a first insulating dielectric layer, a metal via hole is arranged between the top surface and the bottom surface of the first insulating dielectric layer, the circuit board 105 is internally provided with a second insulating dielectric layer, taking a light emitting end as an example, an electric signal is transmitted from the top surface of the circuit board 105 to the bottom surface of the flexible circuit board 600, then is transmitted to the top surface of the flexible circuit board 600 through the metal via hole, then is transmitted to the light emitting assembly 400 through a high-frequency signal wire on the surface of the flexible circuit board 600, and after the electric signal is received by a laser in the light emitting assembly 400, the electric signal is converted into an optical signal and is emitted to the outside of the optical module.

As shown in fig. 6, a plurality of pins are arranged on the tube seat, including a laser positive electrode pin, a laser negative electrode pin, a low-frequency signal pin and a grounding pin, correspondingly, corresponding pin through holes are arranged on the surface, close to the tube seat, of the flexible circuit board, including a laser positive electrode pin through hole, a laser negative electrode pin through hole, a low-frequency signal pin through hole and a grounding pin through hole, and the laser positive electrode pin penetrates through the laser positive electrode pin through hole and is welded and connected with a laser positive electrode signal bonding pad; the laser negative electrode pin penetrates through the laser negative electrode pin through hole and is connected with the laser negative electrode signal bonding pad in a welding way; the low-frequency signal pin penetrates through the low-frequency signal pin through hole and is connected with the low-frequency signal bonding pad in a welding mode. With further reference to fig. 8, in fig. 8, the laser positive signal pad is a laser positive signal pad 610 and the laser negative signal pad is a laser negative signal pad 640; in fig. 8, the ground pin 693 is further included, the ground pin on the tube seat passes through the ground hole 693, one end of the ground hole 693 is connected with the ground plane, and the tube seat is electrically connected with the ground plane through the ground pin; the ground plane is ground layer 690 in fig. 11, ground layer 690 is electrically connected to ground pad 691 and ground pad 692, and ground pad 691 and ground pad 692 are then electrically connected to ground on circuit board 105.

As shown in fig. 7, 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, wherein the first insulating dielectric layer 602 is provided with a metal via hole therethrough; the circuit board 105 includes a top surface 1051, a bottom surface 1053, and a second dielectric layer 1052 disposed between the top surface 1051 and the bottom surface 1053; the flexible circuit board 600 and the circuit board 105 are electrically connected by soldering with solder 604, specifically, the corresponding bonding pads of the flexible circuit board 600 and the circuit board 105 are soldered together by soldering with solder 604; the top surface 1051 of the circuit board 105 is a signal transmission layer, an electrical signal is transmitted from the top surface 1051 of the circuit board 105 to the bottom surface of the flexible circuit board 600 through solder 604, then transmitted to the top surface 601 of the flexible circuit board 600 through metal vias, then transmitted to the light emitting assembly 400 through high frequency signal lines on the surface of the flexible circuit board 600, and after receiving the electrical signal, a laser in the light emitting assembly 400 converts the electrical signal into an optical signal and emits the optical signal to the outside of the optical module.

The top surface of the flexible circuit board 600 is provided with a laser anode signal pad 610 and a first high-frequency signal pad 620, a first high-frequency signal wire 630 is connected between the laser anode 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 cathode signal pad 640 and a second high-frequency signal pad 660, the second high-frequency signal pad 660 is electrically connected with a corresponding high-frequency signal pad on the bottom surface of the flexible circuit board 600 through a metal via hole and then is electrically connected with a corresponding high-frequency signal pad on the top surface of the circuit board, and a second high-frequency signal wire 650 is connected between the laser cathode signal pad 640 and the second high-frequency signal pad 660; when the width of the first high frequency signal line 630 is directly transited to the first high frequency signal pad 620 or the width of the second high frequency signal line 650 is directly transited to the second high frequency signal pad 660, the ground layer 690 on the bottom surface of the flexible circuit board 600 cannot be connected to the signal pad on the bottom surface, so that the first high frequency signal line 630 and the second high frequency signal line 650 are suspended in the corresponding area on the bottom surface, and the suspension causes abrupt impedance changes of the first high frequency signal line 630 and the second high frequency signal line 650, which may cause significant increases, resulting in serious impedance discontinuities, causing large signal reflection, and affecting signal integrity and high frequency performance.

The impedance continuity of the flexible board directly affects the signal integrity of the entire link and even the entire optical module, and is therefore very important for the optimal design of the impedance continuity of the flexible board.

The following describes the solution provided in the present application in detail with reference to fig. 8, 9 and 10; FIG. 8 is a surface structure diagram of a flexible circuit board according to some embodiments; FIG. 9 is an enlarged schematic view of a surface structure of a flexible circuit board according to some embodiments; fig. 10 is another surface structure diagram of a flexible circuit board according to some embodiments.

Fig. 8 and 9 are schematic diagrams of the top surface structure of the flexible circuit board 600, as shown in fig. 8 and 9, the top surface of the flexible circuit board 600 is provided with a laser positive electrode signal pad 610, a laser negative electrode signal pad 640, a first high-frequency signal pad 620 and a second high-frequency signal pad 660, a first high-frequency signal line 630 is provided between the laser positive electrode signal pad 610 and the first high-frequency signal pad 620, a second high-frequency signal line 650 is provided between the laser negative electrode signal pad 640 and the second high-frequency signal pad 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 second high-frequency signal line 650 and the second high-frequency signal pad 660, and the impedance at the first transition region 670 and the second transition region does not have a larger impedance mutation relative to the corresponding high-frequency signal line 680 and the high-frequency signal pad, so that the impedance continuity between the corresponding high-frequency signal line and the corresponding high-frequency signal pad can be increased.

Fig. 10 is a schematic view of the bottom surface structure of a flexible circuit board 600, wherein a ground pin on a header passes through a ground through hole 693, one end of the ground through hole 693 is connected to a ground plane, and the header is electrically connected to the ground plane through the ground pin; the ground plane is ground layer 690 in fig. 10, ground layer 690 is electrically connected to ground pad 691 and ground pad 692, and ground pad 691 and ground pad 692 are then electrically connected to ground on circuit board 105.

Further, as shown in fig. 9, the first transition region 670 includes a first connection region 671 and a second connection region 672, and the second transition region 680 includes a third connection region 681 and a fourth connection region 682; wherein the first high-frequency signal line 630, the first connection region 671, the second connection region 672 and the first high-frequency signal pad 620 are sequentially connected, the width of the first connection region 671 near the end of the first high-frequency signal line 630 is smaller than the width of the Yu Shudi high-frequency signal pad 620, the width near the end of the second connection region 672 is larger than the width of the first high-frequency signal pad 620, and the width of the second connection region 672 is larger than the width of the first high-frequency signal pad 620, wherein the width direction refers to the direction perpendicular to the length direction of the first high-frequency signal line 630; the second connection region 672 is widened, so that the width of the first transition region 670 is increased, the capacitance per unit length between the first high-frequency signal line 630 and the first high-frequency signal pad 620 is increased, the impedance at the connection position of the first high-frequency signal line 630 and the first high-frequency signal pad 620 is reduced, and the impedance continuity between the first high-frequency signal line and the first high-frequency signal pad is optimized; in order to ensure the impedance continuity between the second connection region 672 and the first high-frequency signal line 630, the first transition region 670 further includes a first connection region 671, the width of one side of the first connection region 671 close to the first high-frequency signal line 630 is consistent with the width of the first high-frequency signal line 630, the width of one side of the first connection region 671 close to the first high-frequency signal pad 620 is consistent with the width of the second connection region 672, and thus the first high-frequency signal line 630 and the first high-frequency signal pad 620 sequentially pass through the first connection region 671 and the second connection region 672 to perform gentle transition, so that gradual development of the width from the first high-frequency signal line to the first high-frequency signal pad is realized, larger abrupt changes of impedance are avoided, and the impedance continuity is ensured. As can be seen from fig. 9, the shape of the first connection region 671 is a right trapezoid shape, the shape of the second connection region 672 is a rectangular shape, and the first connection region 671 and the second connection region 672 are metal layers, such as copper layers.

The second transition region 680 includes a third connection region 681 and a fourth connection region 682, the second high frequency signal line 650, the third connection region 681, the fourth connection region 682, and the second high frequency signal pad 660 are sequentially connected, a lateral width of the third connection region 681 near the second high frequency signal line 650 is consistent with a width of the second high frequency signal line 650, a lateral width of the third connection region 681 near the second high frequency signal pad 660 is consistent with a width of the second high frequency signal pad 660, and a width of the second high frequency signal pad 660 is greater than a width of the second high frequency signal pad 660; further, the width of the second transition region 680 is increased by widening the fourth connection region 682, so that the capacitance per unit length between the second high-frequency signal line 650 and the second high-frequency signal pad 660 is increased, the impedance at the connection between the second high-frequency signal line 650 and the second high-frequency signal pad 660 is reduced, and the impedance continuity between the second high-frequency signal line 650 and the second high-frequency signal pad 660 is optimized; and the third connection area 681 can further ensure the impedance continuity between the second high-frequency signal line 650 and the fourth connection area 682, so as to further increase the impedance continuity between the second high-frequency signal line 650 and the second high-frequency signal pad 660, so that the second high-frequency signal line 650 and the second high-frequency signal pad 660 sequentially pass through the third connection area 681 and the fourth connection area 682 to perform gentle transition, thereby realizing gradual development of the width from the second high-frequency signal line to the second high-frequency signal pad, avoiding larger abrupt change of impedance, and ensuring impedance continuity. As can be seen from fig. 10, the third connection region 681 has the shape of an isosceles trapezoid, the fourth connection region 682 has the shape of a rectangle, and the third connection region 681 and the fourth connection region 682 are metal layers, such as copper layers.

Further, in the embodiment of the present application, the widths of the second connection region 672 and the fourth connection region 682 are increased by 4 mils compared with the first high-frequency signal pad 620 and the second high-frequency signal pad 660, respectively, and specifically, may be increased by 2 mils on both left and right sides, respectively; the shapes of the first connection region 671 and the third connection region 681 are approximately trapezoidal; it is to be understood that the embodiment of the present application will be described by taking the first connection region 671 and the third connection region 681 as examples. The shapes of the second connection region 672 and the fourth connection region 682 may be regular shapes such as rectangular, trapezoid, circular, etc., irregular shapes such as butterfly, etc., and any value of the widened sizes, such as 4mil,6mil, etc., within the allowable process range should be taken as the protection scope of the present application; the second connection region 672 has both ends protruding symmetrically or asymmetrically with respect to the first high-frequency signal pad in the width direction, and the second connection region 672 has a width 4mil larger than the first high-frequency signal pad, for example, the first high-frequency signal pads protruding from both ends of the second connection region 672 are 0 and 4mil, 1 and 3mil, 2 and 2mil, respectively. The fourth connection region 682 is likewise arranged; among them, it is preferable that the second connection region 672 protrudes symmetrically with respect to the first high-frequency signal pad in the width direction at both ends, and the fourth connection region 682 protrudes symmetrically with respect to the second high-frequency signal pad in the width direction at both ends, and at this time, the coupling performance between the first high-frequency signal line and the second high-frequency signal line is good. FIG. 11 is a schematic diagram of simulation results of a flexible circuit board according to some embodiments; FIG. 12 is a second schematic diagram of simulation results of a flexible circuit board according to some embodiments; fig. 11 is a simulation result of impedance at a connection point of a high-frequency signal line and a high-frequency signal pad, and fig. 12 is a simulation result of reflection amplitude at a connection point of a high-frequency signal line and a high-frequency signal pad; the schemes corresponding to the curve 1 and the curve 2 in fig. 11 are a conventional scheme and a scheme of the application, wherein the conventional scheme refers to direct connection between a high-frequency signal wire and a high-frequency signal pad, and the scheme of the application refers to transitional connection between the high-frequency signal wire and the high-frequency signal pad through a first connection area and a second connection area; the schemes corresponding to the curve 1 and the curve 2 in fig. 12 are a conventional scheme and the scheme of the application, wherein the conventional scheme refers to direct connection between a high-frequency signal wire and a high-frequency signal pad, and the scheme of the application refers to transitional connection between the high-frequency signal wire and the high-frequency signal pad through a first connection area and a second connection area.

As can be seen from fig. 11, the impedance of the junction in the conventional scheme is 56.1625 Ω, and the impedance of the junction in the scheme of the present application is 54.5496 Ω; the impedance of the junction of the high-frequency signal wire and the high-frequency signal pad is reduced, and compared with a traditional scheme, the impedance continuity between the high-frequency signal wire and the high-frequency signal pad is improved.

As can be seen from FIG. 12, the reflection amplitude corresponding to the frequency of 20GHz in the conventional scheme is-13.8632 dB, the reflection amplitude corresponding to the scheme in the application is-15.8888 dB, and the larger the absolute value is, the better the performance is, so that the scheme provided by the embodiment of the application has certain advantages.

The foregoing is merely a specific embodiment of the disclosure, but the protection scope of the disclosure is not limited thereto, and any person skilled in the art who is skilled in the art will recognize that changes or substitutions are within the technical scope of the disclosure. Therefore, the protection scope of the present disclosure shall be subject to the protection scope of the claims.

Claims (10)

1. An optical module, comprising:

a circuit board;

the light emitting assembly is electrically connected with the circuit board and is used for converting the electric signal into an optical signal;

the flexible circuit board is electrically connected with the circuit board and the light emitting component, and the surface is provided with:

a first high-frequency signal line;

a first high-frequency signal pad which is not connected with the ground layer on the surface of the flexible circuit board, so that a suspension area exists on the bottom surface of the first high-frequency signal wire; a first connection area and a second connection area are arranged between the first high-frequency signal wire and the first high-frequency signal bonding pad, and the second connection area is positioned on the surface of the suspension area; the first high-frequency signal wire, the first connection area, the second connection area and the first high-frequency signal pad are sequentially connected, and the width of the first high-frequency signal pad is larger than that of the first high-frequency signal wire;

one end of the first connecting area is the same as the first high-frequency signal line in width, the other end of the first connecting area is the same as the second connecting area in width, and the second connecting area is larger than the first high-frequency signal bonding pad in width;

wherein the first connection region is trapezoidal, and the second connection region is rectangular.

2. The optical module of claim 1, wherein a width of the first connection region near the first high frequency signal terminal is smaller than the first high frequency signal pad width, and a width near the second connection region is larger than the first high frequency signal pad width.

3. The optical module according to claim 1, wherein both ends of the second connection region are protruded symmetrically with respect to the first high frequency signal pad, respectively, in a width direction.

4. The optical module of claim 1, wherein the first connection region is provided in a right trapezoid shape and the second connection region is provided in a rectangular shape;

the first connection region and the second connection region are both metal layers.

5. The optical module of claim 1, wherein the width of the second connection region is 4 mils or 6 mils greater than the width of the first high frequency signal pad.

6. The optical module of claim 1, wherein the flexible circuit board surface is provided with:

a second high-frequency signal line;

a second high frequency signal pad;

the high-frequency signal wire is characterized in that a third connecting area and a fourth connecting area are arranged between the second high-frequency signal wire and the second high-frequency signal bonding pad, the second high-frequency signal wire, the third connecting area, the fourth connecting area and the second high-frequency signal bonding pad are sequentially connected, the width of the second high-frequency signal bonding pad is larger than that of the second high-frequency signal wire, one end of the third connecting area is identical to that of the second high-frequency signal wire, the other end of the third connecting area is identical to that of the fourth connecting area, and the width of the fourth connecting area is larger than that of the second high-frequency signal bonding pad.

7. The optical module of claim 6, wherein a width of the third connection region near the second high frequency signal terminal is smaller than the second high frequency signal pad width, and a width near the fourth connection region is larger than the second high frequency signal pad width.

8. The optical module according to claim 6, wherein both ends of the fourth connection region are protruded symmetrically with respect to the second high frequency signal pad in a width direction.

9. The light module of claim 7 wherein the third connection region is configured as an isosceles trapezoid and the fourth connection region is configured as a rectangle;

the third connection region and the fourth connection region are both metal layers.

10. The optical module of claim 1, wherein the flexible circuit board bottom surface is electrically connected to the circuit board top surface by soldering;

and a metal via hole is arranged between the corresponding bonding pad on the top surface of the flexible circuit board and the corresponding bonding pad on the bottom surface of the flexible circuit board.