CN110596833B

CN110596833B - Optical module

Info

Publication number: CN110596833B
Application number: CN201911001434.2A
Authority: CN
Inventors: 孙金星
Original assignee: Hisense Broadband Multimedia Technology Co Ltd
Current assignee: Hisense Broadband Multimedia Technology Co Ltd
Priority date: 2019-10-21
Filing date: 2019-10-21
Publication date: 2021-05-14
Anticipated expiration: 2039-10-21
Also published as: CN110596833A

Abstract

The application provides an optical module, including: the circuit board is a multilayer circuit board, an AWG (arrayed waveguide grating) surface mounting metal layer and an FPC (flexible printed circuit) welding point are arranged on the surface layer of the circuit board, a first gap is arranged between the AWG surface mounting metal layer and the FPC welding point, and no metal heat-conducting substance exists in the first gap; intervals are arranged between the projection area of the AWG surface mount metal layer and the projection area of the FPC welding point in the plurality of layers of the circuit board inner layers, and no metal heat-conducting substance exists in the intervals; the light emission secondary module is connected with a flexible circuit board, and the flexible circuit board is welded and connected with an FPC (flexible printed circuit) welding point; the light receiving sub-module comprises an array waveguide grating, and the array waveguide grating is attached to the AWG attaching metal layer. The application provides an optical module, effectively avoids user welded connection FPC's heat to concentrate quick conduction to AWG pastes dress position, effectively prevents that the heat of welded connection circuit board and flexible circuit board from causing array waveguide grating to damage.

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 is mainly used for photoelectric and electro-optical conversion, an electric signal is converted into an optical signal by a transmitting end of the optical module and is transmitted out through an optical fiber, and a received optical signal is converted into an electric signal by a receiving end of the optical module. The current packaging form of the optical module mainly includes a TO (Transistor-out) package and a COB (Chip on Board) package.

However, with the demand for the diversity of optical modules, an optical module including both a TO package and a COB package is now emerging. For example, the transmitter sub-module is packaged in a TO package, and the receiver sub-module is packaged in a COB package. Specifically, the method comprises the following steps: the light emission secondary module is connected with a circuit board of the optical module through an FPC (flexible printed circuit), and the FPC is connected with the circuit board of the optical module through welding; related components of the optical receive sub-module are directly mounted on a circuit board of the optical module, such as a PD (Photo-Diode) chip and an AWG (Arrayed Waveguide Grating). Under the influence of assembly conditions, the optical module is generally assembled with the components of the receive sub-module first, and then the tosa is assembled by FPC soldering. However, the AWG temperature cannot be higher than 150 ℃, and the temperature when the FPC is soldered to the circuit board of the optical module is usually not lower than 300 ℃, which has been found to easily cause AWG damage due to high temperature during the assembly and production process of the optical module.

Therefore, in order to prevent the AWG from being damaged due to the FPC welding in the optical module assembly production process, the distance between the FPC welding point and the welding point of the AWG is usually set to be as large as possible in the production design, but because the area of the circuit board of the optical module is relatively small, other electric devices need to be arranged on the circuit board, the distance between the FPC welding point and the welding point of the AWG is usually only about 2mm, the distance between the FPC welding point and the welding point of the AWG is very close, and the AWG cannot be prevented from being influenced by the high welding temperature of the FPC. Therefore, how to solve the AWG problem is a technical problem that those skilled in the art need to solve.

Disclosure of Invention

The application provides an optical module, which effectively prevents array waveguide grating damage caused by heat of a welding connection circuit board and a flexible circuit board.

The application provides an optical module, includes:

the circuit board is a multilayer circuit board and is provided with a grounding circuit and a signal circuit and used for providing grounding electric connection and signal electric connection, an AWG (arrayed waveguide Grating) surface mounting metal layer and an FPC (flexible printed Circuit) welding point are arranged on the surface layer of the circuit board, a first gap is arranged between the AWG surface mounting metal layer and the FPC welding point, and no metal heat conducting substance exists in the first gap;

the optical transmitter submodule is connected with the signal circuit of the circuit board and used for generating a data optical signal;

the optical receiving sub-module is connected with the signal circuit of the circuit board and used for receiving the data optical signal;

intervals are arranged between the projection area of the AWG surface mount metal layer and the projection area of the FPC welding point in the plurality of layers of the circuit board inner layers, and no metal heat-conducting substance exists in the intervals;

the light emission secondary module is connected with a flexible circuit board, and the flexible circuit board is connected with the FPC welding point in a welding mode;

the light receiving sub-module comprises an array waveguide grating, and the array waveguide grating is attached to the AWG attaching metal layer.

In the optical module that this application provided, set up first clearance through between AWG pastes dress position on the circuit board top layer and the FPC welding position, no metal heat conduction material in the first clearance to AWG pastes dress position and all sets up the interval on a plurality of layers of the projection region of circuit board inlayer and FPC welding position between the projection region of circuit board inlayer, is to set up the metal in the interval and leads the material. So, when carrying out flexible circuit board welded connection circuit board, because do not have metal heat-conducting material from the FPC welding point to between the array waveguide grating, effectively avoid user welded connection flexible circuit board's heat to concentrate quick conduction to AWG and paste dress the position, and can evenly conduct to AWG and paste dress the position through the medium of circuit board self to lead to the fact the damage because of the high temperature of avoiding welding flexible circuit board to array waveguide grating. Therefore, the application provides the optical module, effectively prevents that the heat of welded connection circuit board and flexible circuit board from causing array waveguide grating to damage.

Drawings

In order to more clearly explain the technical solution of the present application, the drawings needed to be used in the embodiments will be briefly described below, and it is obvious to those skilled in the art that other drawings can be obtained according to the drawings without any creative effort.

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

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

fig. 3 is a schematic structural diagram of an optical module provided in an embodiment of the present application;

fig. 4 is an exploded structural schematic diagram of an optical module provided in an embodiment of the present application;

FIG. 5 is a first block diagram of a circuit board according to an embodiment of the present disclosure;

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

FIG. 7 is a third diagram illustrating a structure of a circuit board according to an embodiment of the present disclosure;

FIG. 8 is a front view of a circuit board in an embodiment of the present application;

FIG. 9 is a schematic diagram of a surface metal wiring structure of a circuit board according to an embodiment of the present invention;

FIG. 10 is a diagram illustrating a second metal routing structure of a circuit board according to an embodiment of the present invention;

FIG. 11 is a schematic diagram of a third metal wiring structure of a circuit board according to an embodiment of the present invention;

FIG. 12 is a diagram illustrating a fourth metal routing structure of a circuit board according to an embodiment of the present invention;

fig. 13 is a schematic diagram of a fifth-layer metal wiring structure of the circuit board in the embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.

One of the core links of optical fiber communication is the interconversion of optical and electrical signals. The optical fiber communication uses optical signals carrying information to transmit in information transmission equipment such as optical fibers/optical waveguides, and the information transmission with low cost and low loss can be realized by using the passive transmission characteristic of light in the optical fibers/optical waveguides; meanwhile, the information processing device such as a computer uses an electric signal, and in order to establish 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, it is necessary to perform interconversion between the electric signal and the optical signal.

The optical module realizes the function of interconversion of optical signals and electrical signals in the technical field of optical fiber communication, and the interconversion of the optical signals and the electrical signals is the core function of the optical module. The optical module is electrically connected with an external upper computer through a golden finger on an internal circuit board of the optical module, and the main electrical connection comprises power supply, I2C signals, data signals, grounding and the like; the electrical connection mode realized by the gold finger has become the mainstream connection mode of the optical module industry, and on the basis of the mainstream connection mode, the definition of the pin on the gold finger forms various industry protocols/specifications.

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

One end of the optical fiber 101 is connected with a remote server, one end of the network cable 103 is connected with a local information processing device, and the connection between the local information processing device and the remote server is completed by the connection between the optical fiber 101 and the network cable 103; and the connection between the optical fiber 101 and the network cable 103 is completed by the optical network unit 100 having the optical module 200.

An optical port of the optical module 200 is connected with the optical fiber 101, and establishes bidirectional optical signal connection with the optical fiber 101; an electrical port of the optical module 200 is accessed into the optical network unit 100, and establishes bidirectional electrical signal connection with the optical network unit 100; the interconversion between the optical signal and the electrical signal is realized inside the optical module 200, so that the connection between the optical fiber 101 and the optical network unit 100 is realized; specifically, the 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 unit 100, and the electrical signal from the optical network unit 100 is converted into an optical signal by the optical module 200 and input to the optical fiber 101. The optical module 200 is a tool for realizing the mutual conversion of the photoelectric signals, and has no function of processing data, and information is not changed in the photoelectric conversion process.

The optical network unit is provided with an optical module interface 102, which is used for accessing the optical module 200 and establishing bidirectional electrical signal connection with the optical module 200; the optical network unit is provided with a network cable interface 104, which is used for accessing the network cable 103 and establishing bidirectional electric signal connection with the network cable 103; the optical module 200 and the network cable 103 are connected through the optical network unit 100. Specifically, the optical network unit 100 transmits a 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, and the optical network unit 100 monitors the operation of the optical module 200 as an upper computer of the optical module 200. Unlike the optical module 200, the optical network unit 100 has a certain information processing capability.

To this end, the remote server establishes a bidirectional signal transmission channel with the local information processing device through the optical fiber 101, the optical module 200, the optical network unit 100, and the network cable 103.

Common information processing apparatuses include routers, switches, electronic computers, and the like; the optical network unit 100 is a host computer of the optical module 200, and provides a data signal to the optical module 200 and receives a data signal from the optical module 200, and a common host computer of the optical module 200 also includes an optical line terminal and the like.

Fig. 2 is a schematic diagram of an optical network unit structure. As shown in fig. 2, the optical network unit 100 includes a circuit board 105, and a cage 106 is disposed on a surface of the circuit board 105; an electric connector is arranged in the cage 106 and used for connecting an electric port of an optical module such as a golden finger; the cage 106 is provided with a heat sink 107, and the heat sink 107 has a convex structure such as a fin for increasing a heat radiation area.

The optical module 200 is inserted into an optical network unit, specifically, an electrical port of the optical module is inserted into an electrical connector in the cage 106, and an optical port of the optical module 200 is connected with the optical fiber 101.

The cage 106 is positioned on the circuit board, enclosing the electrical connectors on the circuit board in the cage; the optical module 200 is inserted into a cage, the optical module 200 is held by the cage, and heat generated by the optical module 200 is conducted to the cage through an optical module case and finally diffused by a heat sink 107 on the cage.

Fig. 3 is a schematic structural diagram of an optical module 200 according to an embodiment of the present disclosure, and fig. 4 is an exploded structural diagram of the optical module 200 according to an embodiment of the present disclosure. As shown in fig. 3 and 4, an optical module 200 provided in an embodiment of the present application includes an upper housing 201, a lower housing 202, an unlocking handle, a circuit board 203, and an optical transceiver.

The upper housing 201 is covered on the lower housing 202 to form a package cavity with two openings, and the outer contour of the package cavity is generally in a square shape. Specifically, the lower housing 202 includes a main board and two side boards located at two sides of the main board and arranged perpendicular to the main board; the upper shell 201 comprises a cover plate, and the cover plate covers two side plates of the upper shell 201 to form a wrapping cavity; the upper casing 201 may further include two side walls disposed at two sides of the cover plate and perpendicular to the cover plate, and the two side walls are combined with the two side plates to cover the upper casing 201 on the lower casing 202.

The two openings may be two ends (204, 205) in the same direction, or two openings in different directions; one of the openings is an electric port 204, a golden finger of the circuit board 203 extends out of the electric port 204 and is inserted into an upper computer such as an optical network unit, the other opening is an optical port 205 and is used for external optical fiber access to connect an optical transceiver inside the optical module 200, and photoelectric devices such as the circuit board 203 and the optical transceiver are located in a package cavity.

The assembly mode of combining the upper shell 201 and the lower shell 202 is adopted, so that devices such as a circuit board 203, an optical transceiver and the like can be conveniently installed in the shells, and the outermost packaging protection shell of the optical module is formed by the upper shell and the lower shell. The upper shell 201 and the lower shell 202 are generally made of metal materials, which is beneficial to realizing electromagnetic shielding and heat dissipation; generally, the housing of the optical module 200 is not integrated, so that when devices such as a circuit board are assembled, the positioning component, the heat dissipation structure and the electromagnetic shielding structure cannot be mounted, and the production automation is not facilitated.

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

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

The circuit board 203 is provided with circuit traces, electronic components (such as capacitors, resistors, triodes and MOS transistors) and chips (such as an MCU, a laser driver chip, a limiting amplifier chip, a clock data recovery CDR, a power management chip, and a data processing chip DSP).

The circuit board 203 connects the electrical appliances in the optical module together according to the circuit design through circuit wiring to realize the electrical functions of power supply, electrical signal transmission, grounding and the like.

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

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

Further, the optical transceiver of the optical module 200 provided by the present application includes the tosa 207 and the rosa for the conversion between the electro-optical and the optical-electrical, wherein the tosa 207 adopts the TO package, the rosa adopts the COB package, and the tosa 207 and the rosa have the corresponding optical ports respectively. As shown in fig. 5, the tosa 207 is connected to the circuit board 203 through a flexible circuit board 208, and the tosa 207 mounts the circuit board 203 through the flexible circuit board 208, so as to supply power, transmit electrical signals, and the like to the tosa 207 through the circuit board 203. The optical receive sub-module comprises devices such as a PD chip and an array waveguide grating 206, wherein: the arrayed waveguide grating 206 is covered on the PD chip, the arrayed waveguide grating 206 is used for transmitting the light beam received by the optical module through the optical port 205 to the PD chip, and the PD chip converts the received optical signal into an electrical signal. Specifically, the optical module 200 receives an optical signal from the optical fiber 101, the optical signal is transmitted through the optical port 205 of the optical module 200 to the arrayed waveguide grating 206, the arrayed waveguide grating 206 reflects the optical signal transmitted thereto to the PD chip, and the PD chip converts the received optical signal into an electrical signal.

Fig. 5 is a first schematic structural diagram of a circuit board 203 according to an embodiment of the present application. As shown in fig. 5, the circuit board 203 has the arrayed waveguide grating 206 mounted thereon, the circuit board 203 is connected to one end of a flexible circuit board 208, and the other end of the flexible circuit board 208 is used to connect the tosa 207, so that the tosa 207 is connected to the circuit board 203 through the flexible circuit board 208. In the embodiment of the present application, in order to ensure that the package cavity formed by the upper housing 201 and the lower housing 202 can accommodate the components such as the circuit board 203 and the tosa 207, and avoid interference between the components, the circuit board 203 is selected to be a hard circuit board with an irregular shape. Alternatively, as shown in fig. 5, the circuit board 203 is divided into a left portion and a right portion along the length direction thereof (the left portion and the right portion are relative concepts), the rosa is disposed on the right portion of the circuit board 203, the rosa 207 is connected to the left portion of the circuit board 203 through the flexible circuit board 208, and the length of the left portion of the circuit board 203 is smaller than that of the right side of the circuit board 203, so that a sufficient space is left for placing the rosa 207. The Circuit Board 203 is preferably a PCB (Printed Circuit Board).

In the present embodiment, the flexible circuit board 208 is soldered to the circuit board 203. Optionally, the circuit board 203 is provided with an FPC pad 2032 at a position for solder connection to the flexible circuit board 208. As shown in fig. 5, the left portion of the circuit board 203 is provided with an FPC pad 2032 near the end of the tosa 207, and the flexible circuit board 208 is soldered to the FPC pad 2032.

The arrayed waveguide grating 206 is an optical device, and has a high requirement on installation, for example, to ensure installation stability and relative position stability with an LD chip, so that the arrayed waveguide grating 206 has a high requirement on the flatness of its installation position, but the circuit board 203 itself cannot meet the requirement on the flatness of its installation position by the arrayed waveguide grating 206 due to the limitation of its manufacturing process, and therefore, a coating needs to be disposed on the circuit board 203 at the position for mounting the arrayed waveguide grating 206 to ensure the flatness of its position. The convenience of the coating setting is considered, the coating is prevented from hindering the heat dissipation of the LD chip, the coating is made of metal, the requirement of the arrayed waveguide grating 206 on the smoothness of the circuit board 203 can be met, and meanwhile the heat dissipation of surrounding heating devices can be assisted.

Fig. 6 is a schematic structural diagram of a circuit board 203 according to an embodiment of the present disclosure, fig. 7 is a schematic structural diagram of a circuit board 203 according to an embodiment of the present disclosure, as shown in fig. 6, an AWG mounting metal layer 2031 is disposed at a position on a surface layer of the circuit board 203 for mounting the arrayed waveguide grating 206, and as shown in fig. 7, the arrayed waveguide grating 206 is mounted on the AWG mounting metal layer 2031. Preferably, the AWG mounting metal layer 2031 is a good conductor metal layer such as copper.

Since the optical module 200 has a small structural volume, in order to meet the installation requirement of the circuit board 203 in the housing of the optical module 200, the size of the corresponding circuit board 203 is relatively small, so that in order to meet the requirement of the circuit area layout on the circuit board 203, the circuit board 203 is a multilayer circuit board, and the circuits of the circuit board 203 are integrated and arranged on each layer of the circuit board 203. The number of layers of the circuit board 203 may be selected according to the actual requirements of the circuit layout. Alternatively, the number of layers of the circuit board 203 may be 5, 8, etc.

In order to facilitate the assembly of the tosa 207, the flexible circuit board 208 is usually connected to the tosa 207 before the flexible circuit board 208 is soldered to the circuit board 203, so that in the assembly process of the awg206 and the flexible circuit board 208 on the circuit board 203, the awg206 is first attached to the circuit board 203, and then the flexible circuit board 208 connected to the tosa 207 is soldered to the circuit board 203.

In the process of soldering the circuit board 203 and the flexible circuit board 208, since a large amount of heat is required to weld the solder in the soldering process, when the solder is solidified, a large amount of heat is transferred from the FPC pad 2032 to the circuit board 203, and part of the heat transferred to the circuit board 203 will be transferred to the awg206 through the surface of the circuit board 203, however, the awg206 is usually made of plastic, and when the heat transferred to the awg206 is too much, the awg206 will be deformed, which will affect the normal use of the awg 206.

In the embodiment of the present application, in order to reduce adverse effects on the arrayed waveguide grating 206 caused by the conduction of a large amount of heat to the arrayed waveguide grating 206 during the process of soldering the flexible circuit board 208, a first gap is provided between the AWG mounting metal layer 2031 and the FPC soldering point 2032 on the circuit board 203, and meanwhile, no metal heat-conducting substance is present in the first gap, for example, no circuit trace or no copper is present in the first gap. Because the thermal conductivity of the metal heat-conducting material is higher than that of the circuit board 203, the absence of the metal heat-conducting material in the first gap can prevent the heat conduction rate from being increased from the FPC bonding point 2032 to the arrayed waveguide grating 206 due to the presence of the metal heat-conducting material in the first gap, and prevent the heat generated in the process of welding the circuit board 203 and the flexible circuit board 208 from being transmitted to the arrayed waveguide grating 206 in a concentrated manner, thereby achieving the thermal isolation between the AWG bonding metal layer 2031 on the surface of the circuit board 203 and the FPC bonding point 2032, and preventing the heat welded to the flexible circuit board 208 from being transmitted to the arrayed waveguide grating 206 in a concentrated manner to have adverse effects on the arrayed waveguide.

The heat generated during the soldering process of the circuit board 203 and the flexible circuit board 208 is not only conducted along the surface layer of the circuit board 203 in the transverse direction, but also conducted to the inside of the circuit board 203 in all directions, such as being conducted to the second layer, the third layer, etc. of the circuit board 203 along the surface layer of the circuit board 203 in the longitudinal direction. Therefore, gaps are arranged between the projection area of the AWG surface-mounted metal layer and the projection area of the FPC welding point on the plurality of layers of the inner layers of the circuit board, and no metal heat-conducting substance exists in the gaps. For example, gaps are provided in the projection areas and the peripheries of the first gaps on the second layer, the third layer and the like of the circuit board 203, and no metal heat-conducting substance is provided in the gaps. Specifically, a space is provided on the second layer of the circuit board 203, and the space is located between the projection area of the AWG attachment metal layer 2031 and the projection area of the FPC solder joint 2032 on the second layer of the circuit board 203; a space is provided on the third layer of the circuit board 203 between the projected area of the AWG attachment metal layer 2031 and the projected area of the FPC solder joint 2032 on the third layer of the circuit board 203.

Therefore, when heat generated during the process of soldering the circuit board 203 and the flexible circuit board 208 is conducted into the circuit board 203 along various directions, the adverse effect on the arrayed waveguide grating 206 caused by the fact that the heat generated during the heat conduction process is conducted to the arrayed waveguide grating 206 due to the metal substance existing in the projection area of the first gap on other adjacent layers on the circuit board 203 is avoided. Thus, the AWG mounting metal layer 2031 and the FPC welding point 2032 are thermally isolated from each other on a plurality of layers of the circuit board 203, and heat generated in the process of welding the circuit board 203 and the flexible circuit board 208 is further prevented from being intensively conducted to the arrayed waveguide grating 206.

So, the optical module 200 that this application embodiment provided, set up first clearance through between the array waveguide grating pastes dress position on the circuit board 203 top layer and the flexible circuit board welded connection position, no metal heat conduction material in the first clearance, and array waveguide grating pastes dress position and flexible circuit board welded connection position all sets up the interval on a plurality of layers of circuit board between the projection on circuit board 203, all set up the metal heat conduction material in the interval, effectively avoid the concentrated quick conduction of heat of welded connection circuit board 203 and flexible circuit board 208 to the subsides dress position of array waveguide grating 206, make the heat of welded connection circuit board 203 and flexible circuit board 208 paste the dress position through the even conduction of circuit board 203 self medium to array waveguide grating 206, thereby avoid the high temperature of welded connection flexible circuit board 208 to cause the damage to array waveguide grating 206.

Preferably, the plurality of layers of the circuit board 203 are sequentially connected with the surface layer of the circuit board 203. Wherein the several layers may be selected as the second, third, and fourth layers, etc. of the circuit board 203. In the present embodiment, the second, third, and fourth layers of the circuit board 203 are preferred. Thus, thermal isolation between the AWG mounting metal layer 2031 and the FPC bonding point 2032 can be achieved, and waste of multiple layers of the circuit board 203 can be avoided.

Fig. 8 is a front view of a surface layer of a circuit board 203 according to an embodiment of the present application. The AWG position is shown as an AWG attach metal layer 2031 for attaching the arrayed waveguide grating 206, the FPC bonding position is shown as an FPC bonding point 2032 for bonding the flexible circuit board 208, and a first gap is formed between the AWG position and the FPC bonding position. Fig. 9 is a schematic view of a surface metal wiring structure of the circuit board 203, as shown in fig. 9, no metal heat-conducting material is present in the first gap, for example, no circuit trace is present in the first gap.

In the embodiment of the present application, in order to describe more accurately that the second layer, the third layer and the fourth layer of the circuit board 203 are all provided with intervals between the projection area of the AWG mounting metal layer 2031 and the projection area of the FPC soldering point 2032, the second layer of the circuit board 203 is provided with a second gap, the third layer of the circuit board 203 is provided with a third gap, and the fourth layer of the circuit board 203 is provided with a fourth gap. The relevant arrangements on the second, third and fourth layers on the circuit board 203 are described below in conjunction with the detailed drawings.

Fig. 10 is a schematic diagram of a second-layer metal wiring structure of the circuit board 203. As shown in fig. 10, a gap is formed between the projection area of the AWG attachment metal layer 2031 and the FPC bonding point 2032 on the second layer of the circuit board 203, which is denoted as a second gap, and no metal heat-conducting material such as circuit trace is present in the second gap. Therefore, the second layer of the circuit board 203 is thermally isolated between the projected area of the AWG attachment metal layer 2031 and the projected area of the FPC bonding point 2032, and heat generated during the process of welding the circuit board 203 and the flexible circuit board 208 is prevented from being intensively conducted from the second gap to the AWG attachment metal layer 2031, thereby adversely affecting the difference of the arrayed waveguide grating 206 attached thereto.

Fig. 11 is a schematic diagram of a third-layer metal wiring structure of the circuit board 203. As shown in fig. 11, a gap is formed between the third layer of the circuit board 203 and the projection area of the AWG attachment metal layer 2031 and the FPC pad 2032, and the gap is referred to as a third gap, and no metal heat-conducting substance such as a circuit trace is present in the third gap. Therefore, the third layer of the circuit board 203 is thermally isolated between the projected area of the AWG attachment metal layer 2031 and the projected area of the FPC bonding point 2032, and heat generated in the process of welding the circuit board 203 and the flexible circuit board 208 is prevented from being intensively transferred from the third gap to the AWG attachment metal layer 2031, thereby adversely affecting the difference of the arrayed waveguide grating 206 attached thereto.

Fig. 12 is a schematic diagram of a fourth-layer metal wiring structure of the circuit board 203. As shown in fig. 12, a gap is formed between the projection area of the AWG attachment metal layer 2031 and the FPC bonding point 2032 on the fourth layer of the circuit board 203, which is denoted as a fourth gap, and no metal heat-conducting material such as circuit trace is present in the fourth gap. Therefore, the fourth layer of the circuit board 203 is thermally isolated between the projected area of the AWG attachment metal layer 2031 and the projected area of the FPC bonding point 2032, and heat generated in the process of welding the circuit board 203 and the flexible circuit board 208 is prevented from being intensively conducted from the fourth gap to the AWG attachment metal layer 2031, thereby adversely affecting the difference of the arrayed waveguide grating 206 attached thereto.

Fig. 13 is a schematic diagram of a fifth-layer metal wiring structure of the circuit board 203. As shown in fig. 13, there is a circuit trace between the projected areas of the AWG attach metal layer 2031 and the FPC pad 2032 on the fifth layer of the circuit board 203.

As shown in fig. 9 to 13, in the embodiment of the present application, gaps are provided between the projection areas of the AWG attachment metal layer 2031 and the FPC bonding point 2032 on the second layer, the third layer, and the fourth layer of the circuit board 203, and no metal heat-conducting substance such as circuit routing exists in the gaps, and a power plane or a signal line is routed from the fifth layer of the circuit board 203 between the projection area of the AWG attachment metal layer 2031 and the projection area of the FPC bonding point 2032.

In this application embodiment, through the top layer at circuit board 203, the second floor, third layer and fourth layer set up the clearance, and do not set up metal heat-conducting material in the clearance, the heat of welded connection FPC208 is at the top layer of circuit board 203 to the self medium of AWG206 transmission mainly through circuit board 203, and FPC welding point 2032 is at the second floor of circuit board 203, third layer and fourth layer projection area also are the self medium of circuit board 203 to AWG206, because self medium is plastics, can make even the conduction on circuit board 203 of heat of welded connection FPC208, effectively avoid the concentrated quick conduction to AWG subsides the dress position of welded connection FPC's heat, and then avoid the high temperature of welded FPC208 to cause the damage to AWG.

And then through the top layer at circuit board 203, the second floor, the interval is set up to the third layer and the fourth layer, and do not set up the metal heat conduction material in the interval, can set up the interval between AWG pastes dress metal layer 2031 and FPC welding point 2032 on the circuit board 203 within 1-2mm, for example 1.5mm, can reach the high temperature that avoids welding flexible circuit board 208 and cause the damage to arrayed waveguide grating 206, can also increase the installation compactness of each device on the circuit board 203, be convenient for adapt to the little size demand of circuit board 203.

In the present embodiment, the projections of the second gap, the third gap and the fourth gap on the surface layer of the circuit board 203 cover the first gap. Further, in order to sufficiently avoid the concentrated and rapid conduction of the heat of the solder-connected FPC to the AWG mounting position, the widths of the second gap, the third gap, and the fourth gap are greater than or equal to the width of the first gap, that is, the distance between the projection area of the AWG mounting metal layer 2031 on the second layer, the third layer, and the fourth layer of the circuit board 203 and the projection area of the FPC solder joint 2032 on the circuit board 203 for thermal isolation is greater than or equal to the distance between the surface layers of the circuit board 203 for thermal isolation.

All the embodiments in the present specification are described in a progressive manner, and the same and similar parts among the embodiments may be referred to each other, and each embodiment focuses on the differences from the other embodiments, and the relevant points may be referred to the part of the description of the method embodiment. It is noted that other embodiments of the present invention will become readily apparent to those skilled in the art from consideration of the specification and practice of the invention herein. This application is intended to cover any variations, uses, or adaptations of the invention following, in general, the principles of the invention and including such departures from the present disclosure as come within known or customary practice within the art to which the invention pertains. It is intended that the specification and examples be considered as exemplary only, with a true scope and spirit of the invention being indicated by the following claims.

It will be understood that the present application is not limited to the precise arrangements described above and shown in the drawings and that various modifications and changes may be made without departing from the scope thereof. The scope of the application is limited only by the appended claims.

Claims

1. A light module, comprising:

2. The optical module of claim 1, wherein the plurality of layers of the inner layer of the circuit board are sequentially connected to a surface layer of the circuit board.

3. The optical module of claim 2, wherein the plurality of layers of the circuit board inner layer are a second layer, a third layer, and a fourth layer of the circuit board.

4. The optical module of claim 2, wherein the spacing width provided on the number of layers is greater than or equal to the width of the first gap.

5. The optical module of claim 1, wherein the width of the first gap is 1-2 mm.

6. The optical module of claim 5, wherein the width of the first gap is 1.5 mm.