WO2021057096A1 - Optical transmitter and optical module - Google Patents

Abstract

An optical transmitter (10) and an optical module (200). The optical transmitter (10) is provided with a laser chip (114), a first metal wire (1151), a second metal wire (1152), a transistor seat (11), and a substrate (112) fixed on the transistor seat (11), signal line transmission layers (1131, 1132) being provided on the substrate (112). The laser chip (114) is connected to a signal line transmission layer (1132) corresponding to the anode thereof by means of two or more metal wires (1151, 1152), and only the first metal wire (1151) is directly welded onto a pad (1141) of the laser chip (114). The area of a solder joint formed by the first metal wire (1151) on the pad (1141) is larger than half of the area of the pad (1141). The remaining second metal wire (1152) is welded such that an upper second metal wire (1152) is welded to a first metal wire (1151) at the bottom portion thereof. As such, the number of metal wires (1151, 1152) may be increased without increasing the area of the pad (1141) of the laser chip (114). Compared with a single wire, the total diameter of the metal wires (1151, 1152) may be increased, which may thereby reduce the inductance generated during the working process of the optical module (200) thereof, and which may be beneficial in improving the high-speed photoelectric performance of the optical module (200).

Description

Optical transmitter and optical module

This application is required to be submitted to the Chinese Patent Office on September 25, 2019, with the application number of 201910912788.6, and the invention titled "Optical Transmitter and Optical Module". It is required to be submitted to the China Patent Office on September 25, 2019, with the application number of 201921607886.0, The priority of the Chinese patent application with the title of "Optical Transmitter and Optical Module", the entire content of which is incorporated in this application by reference.

Technical field

This application relates to the field of optical communication technology, and in particular to an optical module.

Background technique

The optical transceiver module, referred to as the optical module, is a standard module in the field of optical communication equipment. A standard optical module usually includes optical emission sub-modules, optical receiving sub-modules, microprocessors and other devices. In addition, there are some optical modules in which separate optical emission sub-modules and optical receiving sub-modules are encapsulated in a metal shell to make bidirectional Optical sub-module, also known as optical transceiver sub-module.

Compared with other packaging technologies, TO (Through-hole)-based packaging technology has the advantages of small parasitic parameters and low process cost. Therefore, the optical transmitter in the optical emission sub-module often adopts the coaxial TO packaging method. Specifically, the light emitter is mainly composed of two parts: a base and a cap. Among them, the pillar of the base is pasted with a ceramic substrate, the surface of the ceramic substrate is plated with a signal transmission layer, the back electrode of the laser chip is pasted on a signal line transmission layer by solder, and the front electrode is connected to the laser chip by a metal wire welded to the laser chip. Another signal line on the transmission layer. Due to the small size of the laser chip, the area of the pad used for welding the metal wire in the front electrode is also very small, so only one ball bonding point, that is, only one metal wire can be hit on the above-mentioned pad.

However, considering the control of the size of the metal ball solder joints, the metal wire will be thinner, that is, the diameter will be smaller, and the parasitic inductance introduced will be relatively large. The higher the communication rate of the optical module, the greater the parasitic inductance introduced by the metal wire, and the more obvious the impact on the high-speed photoelectric performance of the optical module.

Summary of the invention

According to the first aspect of the embodiments of the present application, there is provided an optical transmitter, including:

Tube socket, used to carry components;

The substrate is carried by the tube base, and has a first signal line transmission layer and a second signal line transmission layer formed of metal material on the surface;

In the laser chip, the cathode on the bottom surface is arranged on the surface of the first signal line transmission layer to realize electrical connection, and the anode on the top surface forms a bonding pad;

One end of the first metal wire is welded to the pad, and the other end is welded to the surface of the second signal line transmission layer, and the area of the solder joint formed on the pad by the first metal wire is larger than one-half of the area of the pad;

One end of the second metal wire is welded to one end of the first metal wire, and the other end is welded to the surface of the second signal line transmission layer;

The anode is electrically connected to the second signal line transmission layer through the first metal wire and the second metal wire.

According to the second aspect of the embodiments of the present application, an optical module is provided, and the optical transmitter provided in the first aspect of the embodiments of the present application is provided in the optical module.

Description of the drawings

In order to explain the technical solutions of the present application more clearly, the following will briefly introduce the drawings needed in the embodiments. Obviously, for those of ordinary skill in the art, without paying creative labor, Other drawings can also be obtained from these drawings.

Figure 1 is a schematic diagram of the connection relationship of an optical communication terminal;

Figure 2 is a schematic diagram of the optical network terminal structure;

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

4 is a schematic diagram of an exploded structure of an optical module provided in an embodiment of the application;

FIG. 5 is a schematic structural diagram of an optical transceiver sub-module provided in an embodiment of the application;

6 is a schematic diagram of an exploded structure of a light emitting sub-module provided in an embodiment of the application;

FIG. 7 is a schematic diagram of a first structure of an optical transmitter provided in an embodiment of the application;

FIG. 8 is a schematic diagram of a second structure of an optical transmitter provided in an embodiment of the application.

detailed description

The technical solutions in the embodiments of the present application will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present application. Obviously, the described embodiments are only a part of the embodiments of the present application, rather than all the embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative work shall fall within the protection scope of this application.

One of the core links of optical fiber communication is the conversion of photoelectric signals. Optical fiber communication uses information-carrying optical signals to be transmitted in optical fibers/optical waveguides, and the passive transmission characteristics of light in optical fibers can realize low-cost and low-loss information transmission. However, information processing equipment such as computers uses electrical signals, which requires mutual conversion between electrical signals and optical signals in the signal transmission process.

The optical module implements the above-mentioned photoelectric conversion function in the field of optical fiber communication technology, and the mutual conversion of optical signals and electrical signals is the core function of the optical module. The optical module realizes the electrical connection with the external host computer through the golden finger on the circuit board. The main electrical connections include power supply, I2C signal, data signal transmission and grounding, etc. The electrical connection method realized by the golden finger has become the optical module industry. The standard method, based on this, the circuit board is a necessary technical feature in most optical modules.

FIG. 1 is a schematic diagram of the connection relationship of optical communication terminals provided by some embodiments of the application. As shown in FIG. 1, the connection of the optical communication terminal mainly includes the interconnection between the optical network terminal 100, the optical module 200, the optical fiber 101, and the network cable 103;

One end of the optical fiber 101 is connected to the remote server, and one end of the network cable 103 is connected to the local information processing equipment. The connection between the local information processing equipment and the remote server is realized through the connection of the optical fiber 101 and the network cable 103 to the optical module 200.

The optical interface of the optical module 200 is connected to the optical fiber 101 to establish a two-way optical signal connection with the optical fiber 101; the electrical interface of the optical module 200 is connected to the optical network terminal 100 to establish a two-way electrical signal connection with the optical network terminal 100; the optical module realizes The mutual conversion of optical signals and electrical signals realizes the establishment of information connection between the optical fiber and the optical network terminal. Specifically, the optical signal from the optical fiber 101 is converted into an electrical signal by the optical module 200 and then input into the optical network terminal 100, and the electrical signal from the optical network terminal 100 is converted into an optical signal by the optical module 200 and input into the optical fiber 101. The optical module 200 is a tool for realizing the mutual conversion of photoelectric signals, and does not have the function of processing data. During the foregoing photoelectric conversion process, the information has not changed.

The optical network terminal 100 has an optical module interface 102, which is used to connect to the optical module 200 and establish a two-way electrical signal connection with the optical module 200; the optical network terminal has a network cable interface 104, which is used to connect to the network cable 103 and establish a two-way connection with the network cable 103. Electrical signal connection; a connection is established between the optical module 200 and the network cable 103 through the optical network terminal 100. Specifically, the optical network terminal 100 transmits the signal from the optical module to the network cable 103, and transmits the signal from the network cable 103 to the optical module 200 , The optical network terminal 100 is used as the upper computer of the optical module to monitor the operation of the optical module.

So far, the remote server has established a two-way signal transmission channel with the local information processing equipment through optical fibers, optical modules, optical network terminals and network cables.

Common information processing equipment includes routers, switches, electronic computers, etc.; the optical network terminal is the upper computer of the optical module, which provides data signals to the optical module and receives data signals from the optical module. The common optical module upper computer also has an optical network Unit ONU, optical line terminal OLT, data center server, data center switch, etc.

Figure 2 is a schematic diagram of the optical network terminal structure. As shown in FIG. 2, the optical network terminal 100 has a circuit board 105, and a cage 106 is provided on the surface of the circuit board 105; an electrical connector is provided in the cage 106 for accessing the electrical interface of the optical module, such as a golden finger; A heat sink 107 is provided on the cage 106, and the heat sink 107 has a convex structure such as fins to increase the heat dissipation area.

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

The cage 106 is located on the circuit board and wraps the electrical connectors on the circuit board in the cage; the optical module is inserted into the cage, and the optical module is fixed by the cage, and the heat generated by the optical module is transmitted to the cage 106 through the optical module housing, and finally passes through the cage The upper radiator 107 performs diffusion.

FIG. 3 is a schematic structural diagram of an optical module 200 according to an embodiment of this application, and FIG. 4 is a schematic structural diagram of an optical module 200 according to an embodiment of this application. As shown in FIGS. 3 and 4, the optical module 200 provided by the embodiment of the present application includes an optical transceiver sub-module 205, and also includes an upper housing 201, a lower housing 202, an unlocking handle 203 and a circuit board 204.

The upper shell 201 and the lower shell 202 form a wrapping cavity with two openings, which can be opened at both ends (206, 207) in the same direction, or at two openings in different directions; one of the openings The electrical interface 206 is used for inserting into a host computer such as an optical network terminal, and the other opening is an optical interface 207, which is used for external optical fiber access to connect the internal optical fiber. Optoelectronic devices such as the circuit board 204 are located in the package cavity.

In some embodiments, the upper housing 201 and the lower housing 202 are made of metal materials, which is beneficial to realize electromagnetic shielding and heat dissipation; the assembly method of the upper housing 201 and the lower housing 202 is adopted to facilitate the installation of the circuit board 204 and other components on the In the housing, the housing of the optical module is generally not made into an integrated structure, so when assembling circuit boards and other devices, positioning components, heat dissipation and electromagnetic shielding structures cannot be installed, and it is not conducive to production automation.

The unlocking handle 203 is located on the outer wall of the package cavity/lower housing 202. Pulling the end of the unlocking handle can make the unlocking handle move relative to the outer wall surface; when the optical module is inserted into the upper computer, the unlocking handle 203 fixes the optical module to the cage of the upper computer Here, by pulling the unlocking handle 203 to release the engagement relationship between the optical module and the host computer, the optical module can be withdrawn from the cage of the host computer.

The optical transceiver module 205 is used to transmit and receive laser light, so that the optical module 200 transmits and receives optical signals. FIG. 5 is a schematic structural diagram of an optical transceiver sub-module provided in an embodiment of the application. As shown in FIG. 5, the optical transceiver module 300 includes an optical transmitter 10, a rectangular tube body 20, and an optical receiver 40.

As shown in FIG. 5, the circular square tube body 20 is used to carry and fix the light transmitter 10 and the light receiver 40. In the embodiment of the present application, the circular square tube body 20 generally adopts a metal material, which is beneficial to realize electromagnetic shielding and heat dissipation. A first nozzle and a second nozzle are provided on the circular square tube body 20. Generally, the first nozzle and the second nozzle are respectively arranged on adjacent side walls of the circular square tube body 20. In some embodiments of the present application, the first nozzle is disposed on the side wall of the circular square tube body 20 in the length direction, and the second nozzle is disposed on the side wall of the circular square tube body 20 in the width direction.

The light transmitter 10 is embedded in the first nozzle, through the first nozzle, the light transmitter 10 thermally contacts the circular square tube body 20; the light receiver 40 is embedded in the second nozzle, and the second nozzle thermally contacts the circular square tube体20. In some embodiments of the present application, the optical transmitter 10 and the optical receiver 40 are directly press-fitted into the rectangular tube body 20, and the rectangular tube body 20 is in contact with the optical transmitter 10 and the optical receiver 40 directly or through a thermally conductive medium. In this way, the square tube body 20 can be used for the heat dissipation of the light transmitter 10 and the light receiver 40 to ensure the heat dissipation effect of the light transmitter 10 and the light receiver 40. The optical fiber adapter 30 is embedded on the other side of the circular square tube body 20 and is used for connecting optical fibers to the optical transceiver sub-modules.

It should be noted that, in this embodiment, the optical transmitter 10 and the optical receiver 40 are packaged as an example. In specific implementation, an independent package structure may also be used. FIG. 6 is a schematic diagram of an exploded structure of a light emitting sub-module provided in an embodiment of the application. As shown in FIG. 6, the light emitting sub-module includes a light emitter (consisting of two parts of a tube base 11 and a tube cap 12 ), a package 50, a connector 60 and an optical fiber adapter 30 from left to right.

FIG. 7 is a schematic diagram of a first structure of an optical transmitter provided in an embodiment of this application; FIG. 8 is a schematic diagram of a second structure of an optical transmitter provided in an embodiment of this application. As shown in Figures 7 and 8, the optical transmitter 10 in this embodiment adopts a coaxial TO package. It should be noted that only the structure of the base part is shown in the figure, and the cap part is not shown in the figure. For the specific structure, please refer to the cap in FIG. 6.

Wherein, the tube base 11 is usually designed as a flat cylindrical structure for carrying various devices in the light emitter 10. A number of pin through holes for the pins 116 to pass through are provided on the tube socket 11, and some of the pins pass through the pin through holes and protrude from the top surface of the tube socket 11 to be fixed on the tube socket 11. Then, the other end of the pin 116 can be connected to the circuit board 204 in the optical module.

The pipe socket 11 is provided with a semi-cylindrical column 111, wherein the column 111 can be an integral structure with the pipe socket 11. The column 111 can be made of alloys, such as copper alloys, nickel alloys, etc., which mainly perform heat dissipation and load-bearing functions, such as It is used to carry the laser chip 114 and assist its heat dissipation. It should be noted that the structure for fixing the laser chip 114 is not limited to the column 111 provided in this embodiment, and it can be designed in other shapes, and it can also be replaced with a heat sink fixed on the tube base.

In some embodiments of the present application, as shown in FIG. 8, in order to facilitate the control of the conduction path and heat dissipation of the laser chip 114, the laser chip 114 is attached to the column 111 through the substrate 112, wherein the substrate 112 and the column 111 can be fixedly connected Solder is used for welding and fixing, and the substrate 112 can be made of ceramic materials such as aluminum nitride and alumina. Of course, other materials can also be used. In some embodiments of the present application, the first signal line transmission layer 1131 and the second signal line transmission layer 1132 made of metal are provided on the substrate 112, and the first signal line transmission layer 1131 and the second signal line transmission layer 1132 are arranged between the first signal line transmission layer 1131 and the second signal line transmission layer 1132. With a certain insulation gap, the first signal line transmission layer 1131 and the second signal line transmission layer 1132 are respectively connected to one pin, for example, the first signal line transmission layer 1131 is connected to the laser cathode drive pin and the second signal line transmission layer 1132 is connected to the laser anode drive pin.

As shown in FIG. 8, the cathode and anode of the laser chip 114 in this embodiment are arranged on two opposite surfaces, wherein the lower surface (bottom surface) is provided with a cathode, and the upper surface (top surface) is provided with an anode. In this embodiment, in order to distinguish two opposite surfaces, it is described as an upper surface and a lower surface. The lower surface of the laser chip 114, that is, its cathode, is mounted on the first signal line transmission layer 1131. In order to facilitate wire bonding on the anode of the laser chip 114, the upper surface is provided with a bonding pad 1141, and the bonding pad 1141 is connected to the laser chip. 114's anode connection.

Specifically, in this embodiment, two metal wires are selected, namely the first metal wire 1151 and the second metal wire 1152. The first metal wire 1151 and the second metal wire 1152 can be gold wire wires made of gold. Can be other metal materials. One end of the first metal wire 1151 is soldered to the pad 1141, and the other end is connected to the second signal line transmission layer 1132. The part where the first metal wire 1151 contacts the pad 1141 is called a solder joint, and the first metal The area of the solder joint formed by the wire 1151 on the pad 1141 is larger than one-half of the area of the pad 1141. At the same time, one end of the second metal wire 1152 is welded to the first metal wire 1151, wherein the second metal wire 1152 is preferably welded close to the solder joint formed by the first metal wire 1151 and the pad 1141, or directly welded On the solder joint; the other end of the second metal wire 1152 is also connected to the second signal line transmission layer 1132.

In this way, the anode of the laser chip 114 is connected to the second signal line transmission layer 1132 through two metal wires, and because the first metal wire 1151 is directly welded to the pad 1141, and the second metal wire 1152 is welded to the first metal wire. On the wire 1151, only one solder joint is formed on the bonding pad 1141 of the laser chip with the two metal wires. Therefore, the light emitter provided by the implementation of the present application can increase the number of metal wires without increasing the area of the laser chip pad, and can increase the total diameter of the metal wires compared with a single metal wire. According to the inductance calculation formula, the inductance L∝1/r,r is the radius of the wire. Therefore, when the total diameter of the metal wire increases, the parasitic inductance generated during the operation of the optical module will also decrease, and the electromagnetic interference caused by it will also decrease. It will be reduced accordingly, which in turn will help improve the high-speed optoelectronic performance of the optical module.

Of course, this embodiment only takes the welding of two metal wires as an example, and more wires, such as three or four wires, can be set as needed, and the upper metal wire is welded to the metal wire at the bottom during wire bonding.

In an embodiment of the present application, in order to increase the firmness of the metal wire welding and reduce the contact resistance between the metal wire and the pad, in this embodiment, when the metal wire is welded, the first metal wire 1151 is now After one end of the metal solder ball 1153 is melted into a round ball by high temperature, then, by applying a certain pressure, the first metal wire 1151 is soldered to the pad 1141 through the metal solder ball 1153. Similarly, one end of the second metal wire 1152 is melted into a round metal solder ball 1154 at high temperature. In order to facilitate the welding of the second metal wire 1152, a certain pressure is applied to make the second metal wire 1152 pass through the metal The solder ball 1154 is soldered on the metal solder ball 1153 of the first metal wire 1151.

In order to ensure the firmness of the bonding wire, in this embodiment, the diameter of the metal solder ball 1154 of the second metal wire 1152 is less than or equal to the diameter of the metal solder ball 1153 of the first metal wire 1151. That is, when multiple metal wires are welded, each wire The diameter of the solder balls decreases sequentially from top to bottom. In this embodiment, the direction close to the pad is referred to as bottom.

According to the inductance L∝Ln, Ln is the length of the wire, it can be seen that the longer the metal wire, the greater the parasitic inductance generated. Therefore, the length of each metal wire should be as short as possible, but it needs to be welded to the second signal wire. Conditions on the transport layer 1132. Based on the above reasons, this embodiment sets the length difference between the first metal wire 1151 and the second metal wire 1152 to be as small as possible. At the same time, since the second metal wire 1152 is welded to the first metal wire 1151, the length of both There will be a difference. Therefore, in this embodiment, the difference between the two is set to be less than the first preset value and greater than or equal to 0, and its specific value is set according to the requirement that both wires can be soldered on the signal line transmission layer.

In some embodiments of the present application, in order to increase the welding speed, in this embodiment, the other end of the first metal wire 1151 is welded to the second signal line transmission layer 1132 by pressure welding, for example, gold wire bonding is used. The wedge presses it on the second signal line transmission layer 1132. In the first metal wire 1151, the contact point with the second signal line transmission layer 1132 is called the first solder joint 1155. Similarly, the other end of the second metal wire 1152 is welded to the second signal line transmission layer 1132 by pressure welding, and the contact point with the second signal line transmission layer 1132 is called the second solder joint 1156.

Since the solder joints of the metal wires on the second signal line transmission layer 1132 are usually formed by pressing on the second signal line transmission layer 1132, in order to prevent the subsequent welding of the metal wires from affecting the welded metal wires In this embodiment, the welding points of the first metal wire 1151 and the second metal wire 1152 on the second signal line transmission layer 1132 have a certain distance L between each other. At the same time, because the distance between the two metal wires is larger, the length of the corresponding metal wire is longer. Therefore, to reduce the inductance value of the metal wire as much as possible and the requirement of the gold wire bonding wedge for the solder joint spacing, you can set adjacent The distance L between the welding points of the metal wires on the second signal line transmission layer 1132 is any value between 50 and 150 um.

In the city, if the second metal wire 1152 is soldered to the metal solder ball 1153 of the first metal wire 1151 through the metal solder ball 1154, the first metal wire 1151 and the second metal wire 1152 form a certain angle θ. Taking into account factors such as the distance between the two signal line transmission layers, the size of the laser chip and its pasting position, this embodiment sets the angle between the first metal wire 1151 and the second metal wire 1152 to be greater than or equal to 15° and less than 180 °.

The embodiment of the present application is only an example of attaching a laser chip to the tube socket. In the specific implementation process, two or more may be attached to realize the emission of multi-optical optical signals.

In addition, other components can also be provided in the tube socket of the light emitter, such as a backlight detector 117 for detecting the luminous power of the laser chip 114, and for obtaining the temperature of the column 111 to achieve the working temperature of the laser chip 114. The thermistor for monitoring, and the thermoelectric cooler for radiating the laser chip 114, etc.

Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the application, not to limit them; although the application has been described in detail with reference to the foregoing embodiments, those of ordinary skill in the art should understand that: The technical solutions recorded in the foregoing embodiments are modified, or some of the technical features are equivalently replaced; these modifications or replacements do not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims (9)

1. A light emitter, which is characterized in that it comprises:

   Tube socket, used to carry components;

   A substrate, which is carried by the tube base, and has a first signal line transmission layer and a second signal line transmission layer formed of a metal material on the surface;

   In the laser chip, the cathode on the bottom surface is arranged on the surface of the first signal line transmission layer to realize electrical connection, and the anode on the top surface forms a bonding pad;

   One end of the first metal wire is welded to the pad, and the other end is welded to the surface of the second signal line transmission layer. The area of the solder joint formed by the first metal wire on the pad is larger than the pad Half of the area;

   One end of the second metal wire is welded to one end of the first metal wire, and the other end is welded to the surface of the second signal line transmission layer;

   The anode is electrically connected to the second signal line transmission layer through the first metal wire and the second metal wire.
2. 4. The light emitter of claim 1, wherein the difference in length between the first metal wire and the second metal wire is greater than or equal to 0 and less than a first preset value.
3. The optical transmitter of claim 1, wherein the first metal wire forms a first solder joint on the second signal line transmission layer, and the second metal wire transmits on the second signal line. A second solder joint is formed on the layer, and there is a certain distance between the first solder joint and the second solder joint.
4. The light emitter according to claim 3, wherein the distance between the first solder joint and the second solder joint is any value between 50-150um.
5. The light emitter according to claim 1, wherein one end of the first metal wire is melted into a metal solder ball and then soldered on the pad, and one end of the second metal wire is melted into a metal solder ball. The ball is then welded on the metal solder ball of the first metal wire.
6. The light transmitter of claim 5, wherein the angle between the first metal wire and the second metal wire is greater than or equal to 15° and less than 180°.
7. The light emitter of claim 1, wherein the diameter of the metal solder ball of the second metal wire is smaller than or equal to the diameter of the metal solder ball of the first metal wire.
8. The light transmitter according to claim 1, wherein the first metal wire and the second metal wire are gold wire wires.
9. An optical module, characterized in that the optical module comprises the optical transmitter according to any one of claims 1 to 8.

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