A laser light source partition packaging structure for a dTOF ranging system

Abstract

The application discloses a kind of partitioned packaging structure of laser light source for dTOF ranging system, the light-emitting hole of the laser light source is divided into multiple groups, each group corresponds to a light-emitting area respectively;Each area has several rows of light-emitting holes, and the rows of light-emitting holes in all areas are periodically interleaved arranged;Each row of light-emitting holes is communicated with the wire bonding area of the side edge of laser light source, and the wire bonding area is electrically connected with the pad of the corresponding peripheral power supply circuit by gold wire;The wire bonding areas connected by the multiple rows of light-emitting holes belonging to the same area are connected to the same pad.The partitioned packaging of the laser light source of the application is simple and compact, makes full use of the limited total area of light source light-emitting, and is easy to package, manufacture and produce.

Description

TECHNICAL FIELD

[0001] The present application relates to the field of optoelectronic technology, in particular to a laser light source partition packaging structure for a dTOF ranging system. BACKGROUND

[0002] 3D imaging devices can greatly enrich the user experience and improve product competitiveness. Unlike traditional 2D imaging devices such as cameras, which can only obtain the planar 2D information of an object, 3D imaging devices can also obtain the depth information of an object, which is a ranging system and can construct a three-dimensional 3D model. Therefore, 3D imaging devices are widely used in industrial measurement, part modeling, medical diagnosis, security monitoring, machine vision, biometric identification, augmented reality AR, virtual reality VR and other fields, and have great application value.

[0003] TOF is the abbreviation of Time-Of-Flight, which is the time interval from the emission time of the emitted light to the reflection of the object to the receiving end. According to the principle of constant light speed, distance measurement can be realized, which is a commonly used technical solution for 3D imaging devices. There are two TOF technical routes: iTOF(indirect-TOF) and dTOF(direct-TOF). The iTOF technology emits a time-periodically modulated laser to the surface of the object through a laser emitting device, and the returned light produces a time delay relative to the incident light in time sequence, which is specifically manifested as a phase delay. The size of the phase delay has a corresponding calculation relationship with the flight time of the light. iTOF measures the phase delay to "indirectly" obtain the flight time of the light, and then realizes distance measurement. The dTOF technology directly measures the flight time Δt. It uses a pulse debugging signal mode, and each pixel inside the sensor directly measures the round-trip time of the photon. It has the advantage of high sensitivity, avoids various problems caused by measuring the phase difference of the round-trip signal, and does not have the process of photoelectron accumulation. Its measurement accuracy is less affected by light noise, and the requirement of low signal-to-noise ratio is conducive to the reduction of system power consumption. In terms of ranging range, anti-interference and power consumption, dTOF has more advantages and wider application scenarios.

[0004] The time flight depth camera described in the existing patent applications with publication numbers CN209894976U and CN212905431U is very important for a ranging system or a 3D imaging device based on the principle of dTOF technology. Compared with an iTOF ranging system, the dTOF ranging system often needs a laser light source to emit laser light in different regions at different times due to the particularity of the receiving end sensor. Specifically, different dTOF optical system schemes have different partition methods, and the corresponding laser light source packaging method on the PCBA carrier plate is also different. SUMMARY

[0005] The present application provides a laser light source partition packaging structure for a dTOF ranging system, which is simple and compact in partition and packaging of the laser light source, fully utilizes the limited total area of the light source, and is easy to package, manufacture and produce.

[0006] In order to achieve the above purpose, the present application adopts the following technical scheme:

[0007] A laser light source partition packaging structure for a dTOF ranging system, the light emitting holes of the laser light source are divided into multiple groups, each group corresponding to a light emitting region;

[0008] Each region has a plurality of rows of light emitting holes, and the rows of light emitting holes in all regions are periodically interleaved;

[0009] Each row of light emitting holes is in communication with a wire bonding region on the side of the laser light source, and the wire bonding region is electrically connected to a pad of the corresponding peripheral power supply circuit through a gold wire;

[0010] The wire bonding regions connected to the multiple rows of light emitting holes in the same region are connected to the same pad.

[0011] The present application divides the laser light source into multiple independently controlled light emitting regions, and the wire bonding regions connected to the light emitting holes in each region are electrically connected to the pads through gold wires. When the peripheral circuit supplies power to any pad, the light emitting holes in the corresponding region will be lit to emit laser light, realizing the function of multiple partitioned light emission.

[0012] As a preferred embodiment, the laser light source has at least two conductive connection layers, and the multiple regions are uniformly arranged on different conductive connection layers.

[0013] According to the structure of the laser light source, when there are multiple wire connection layers, the light emitting regions can be arranged on different conductive connection layers, and the adjacent conductive connection layers are electrically isolated by an insulating layer to prevent electrical conduction between different regions.

[0014] As preferred, the emitting surface of the laser light source is provided with an identification alignment mark and a traceability code area. The identification alignment mark is used for machine grabbing identification and accurate alignment of the VCSEL in the packaging manufacturing process, which can be any simple pattern such as a star, a cross. The traceability code area is used to place the identity code of the laser light source, which can be a letter, a number, a two-dimensional code, etc.

[0015] As preferred, each row of emitting holes is connected with a wire bonding area, and each wire bonding area is connected with a pad through a gold wire.

[0016] When all the emitting areas are located in the same conductive connection layer, there should be no intersection between different areas, and the wire bonding areas corresponding to different areas should be mutually seated. In this case, each row of emitting holes can be provided with an independent wire bonding area, and multiple wire bonding areas can be connected to the same pad through gold wires.

[0017] As preferred, multiple rows of emitting holes belonging to the same area are connected to the same wire bonding area, and the wire bonding area is connected to the pad through multiple gold wires.

[0018] The emitting holes belonging to the same group can also be connected to the same wire bonding area, which is usually arranged in a long strip shape. In addition, due to the limited current carrying capacity of a single gold wire, multiple gold wires are usually used to connect the wire bonding area and the pad of the power supply circuit in order to increase the current carrying capacity.

[0019] As preferred, the emitting holes in adjacent two rows are distributed in a staggered manner.

[0020] Generally, the emitting holes in adjacent rows are arranged in a 1 / 2 staggered manner, i.e., the emitting holes in the next row are located on the middle line between the adjacent emitting holes in the previous row. If the ranging system has sufficient requirements in terms of light source area and total number of emitting holes, 1 / 3 staggered arrangement, 1 / 4 staggered arrangement, etc. can also be used. Alternatively, the emitting holes can be arranged without staggering.

[0021] As preferred, in each row of emitting holes, the boundary of the area between the adjacent two emitting holes is inwardly retracted; correspondingly, the boundary of the area of the adjacent row of emitting holes is protruded, which is complementary to the retracted position.

[0022] Through the retraction and pattern of the boundary of each row of emitting holes, a nearly rhombus-shaped boundary shape (which can also be understood as a wavy or toothed shape) is formed. The protruding part of the rhombus is located at the intersection of the previous row and the next row of emitting holes, which can fully utilize the gap in the y direction generated by the intersection of different rows to maximize the area of the grouping area, i.e., the planar area of the respective conductive connection layer, so as to enable it to carry a larger injection current and have better heat dissipation performance, thereby improving the light emitting efficiency of the emitting holes.

[0023] As preferred, the area boundary of different conductive connection layers can be partially overlapped, further expanding the range of the light emitting area, and improving the light emitting efficiency and heat dissipation performance of the light emitting hole.

[0024] As preferred, the wire bonding area position of the light emitting hole in different areas is staggered. When multiple wire bonding areas are in the same layer of the laser light source, there should be no intersection between different areas, otherwise series conduction will occur, and the grouping and partitioning function will be lost. BRIEF DESCRIPTION OF DRAWINGS

[0025] Figure 1 A schematic diagram of a laser light source partition packaging structure according to an embodiment of the present application;

[0026] Figure 2 A schematic diagram of the structure stack of a VCSEL light source according to an embodiment of the present application;

[0027] Figure 3 A schematic diagram of a laser light source partition packaging structure according to an embodiment of the present application;

[0028] Figure 4 A schematic diagram of a laser light source partition packaging structure according to an embodiment of the present application;

[0029] Figure 5 A schematic diagram of a laser light source partition packaging structure according to an embodiment of the present application;

[0030] Figure 6 A schematic diagram of a laser light source partition packaging structure according to an embodiment of the present application. DETAILED DESCRIPTION

[0031] In the following description, numerous specific details are set forth in order to provide a thorough understanding of the present application. However, it will be apparent to one skilled in the art that the present application can be practiced without the specific details presented herein. In other instances, well-known methods have not been described in detail in order to avoid obscuring aspects of the present application. Reference throughout this specification to "an aspect" means any one of the aspects described herein, or any combination of those aspects, or any other aspect of the present application.

[0032] Embodiments of the present application are described in detail below with reference to the attached drawing figures, wherein the same or like component have the same or similar designations. The embodiments described below are presented by way of example to explain the present application, and are not intended to limit the present application.

[0033] In the present application, unless otherwise explicitly specified and limited, the terms "mounting", "connecting", "connecting", "fixing" and the like should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium, or it can be connected inside two elements. For those skilled in the art, the specific meaning of the above terms in the present application can be understood according to the specific circumstances.

[0034] As Figure 1 shown is an embodiment of the present application, the laser light source 10 is preferably a vertical cavity surface emitting laser (VCSEL), which includes multiple rows of light emitting holes 1010 arranged in parallel and staggered, each of which can emit a laser beam. In this embodiment, the light emitting holes of the laser light source 10 are divided into four groups corresponding to regions 106, 107, 108, and 109, which are arranged periodically from top to bottom. In this diagram, each region includes three rows of light emitting holes 1010. The light emitting holes of region 106 are connected to the wire bonding area 101 for conduction. The wire bonding area 101 is long and narrow, located on the side of the laser light source 10, and is used to connect the pads of the peripheral power supply circuit of the light source chip through "gold wire" to achieve the purpose of the peripheral power supply circuit injecting current into the corresponding region of the light emitting hole to emit laser. In Figure 1 , the electrical connection between the wire bonding area 101 and the pads 201 of the peripheral power supply circuit is realized by the conduction of the gold wire 2010. The current carrying capacity of a single gold wire is limited, and generally multiple gold wires are used to connect the wire bonding area and the power supply circuit pad to increase the current carrying capacity, as Figure 1 shows six gold wires for connection.

[0035] Similarly, the wire bonding area 102 connected to the light emitting holes of region 107 is electrically connected to the pads 202 through the gold wire 2011, the wire bonding area 103 connected to the light emitting holes of region 108 is electrically connected to the pads 203 through the gold wire, and the wire bonding area 104 connected to the light emitting holes of region 109 is electrically connected to the pads 204 through the gold wire.

[0036] Therefore, when the peripheral circuit selects to supply power to any pad 201, 202, 203, or 204, the VCSEL light emitting holes of the corresponding region will be lit to emit laser light, achieving the function of four groups of divided light emission. The specific lighting sequence and the number of regions lit at the same time (for example, lighting two or more regions at a time) can be configured by different dTOF ranging systems as needed.

[0037] In this embodiment, the long and narrow wire bonding area 101 intersects with the light emitting hole region 107 of the VCSEL in the top view, as Figure 1As shown by the dotted circles in the figure, they are located in different layers in the cross-section diagram and are not in an electrically conductive state. Figure 2 The partial cross-sectional view shown shows that the laser light source 10 includes two conductive connection layers: a first conductive connection layer 301 and a second conductive connection layer 303 . Figure 1 The white transparent part of the laser light source 10, including the light-emitting hole area 106, area 108, bonding area 101 and bonding area 103, are all located in the first conductive connection layer 301. The shaded part, including the light-emitting hole area 107, area 109, bonding area 102 and bonding area 104, are all located in the second conductive connection layer 303. There is also an insulating layer 302 between the first conductive connection layer 301 and the second conductive connection layer 303 for electrical isolation to prevent electrical conduction between different areas and the loss of the partitioning and grouping function. The laser light source 10 also includes other layers, which are all conventional process layers in the VCSEL structure and are not described in detail here.

[0038] In this embodiment, the laser light source 10 further includes an identification mark 1011 and a traceability code area 1012. The identification mark 1011 is used for machine recognition and accurate alignment during the VCSEL packaging and manufacturing process and can be any simple pattern, such as a star or a cross. The traceability code area 1012 is used to place the laser light source's identification code and can be a pattern such as letters, numbers, or a QR code.

[0039] It should be pointed out that Figure 1 In this embodiment, adjacent rows of light-emitting apertures are arranged in a 1 / 2 staggered arrangement, meaning that the light-emitting apertures in the next row are located on the midline between adjacent light-emitting apertures in the previous row. This is a common practice in the industry and offers the advantage of maximizing the spacing between any two light-emitting apertures, given the same VCSEL area and a predetermined total number of light-emitting apertures. This allows for faster heat dissipation, higher current carrying capacity, and improved luminous efficiency. If the ranging system meets the requirements for light source area and total number of light-emitting apertures, a 1 / 3 staggered arrangement, a 1 / 4 staggered arrangement, or even a non-zero staggered arrangement can also be employed, without departing from the scope of this embodiment.

[0040] It should be pointed out that Figure 1 In the embodiment, bonding areas 101 to 104 and pads 201 to 204 are all elongated strips. However, in practical applications, these shapes are not limited to these and can be configured in various shapes, such as zigzag, racetrack, or L-shaped, as needed. Furthermore, the four-group partitioning scheme of the VCSEL with two conductive connection layers can also be used for partitioning in two, three, five, or six groups. The conductive connection layers of this embodiment can even be expanded to three or four layers as needed. All of these scenarios fall within the scope of this embodiment.

[0041] Figure 3 is another embodiment of the present application, which is different from Figure 1 in that the boundary shape of the area 106, the area 107, the area 108, and the area 109 surrounding the light emitting holes is approximately a rhombus (irregular boundary), and the convex part of the rhombus is at the place where the light emitting holes of the upper row and the lower row are staggered, which is different from Figure 1 the long strip-shaped partition. The advantage of this is to make full use of the gap in the y direction caused by the staggering between different rows to expand the area of the grouping area, i.e. the planar area of the respective conductive connection layer, as much as possible, so that it can carry a larger injection current and has better heat dissipation performance, thereby improving the light emitting efficiency of the light emitting holes. Since the first conductive connection layer and the second conductive connection layer do not interfere with each other, the area 106 and the area 108 are in the same layer, and the area 107 and the area 109 are in the same layer, then in some embodiments, the boundary of the area 106 and the area 108 can be further expanded above the area 107 and the area 109, and the boundary of the area 107 and the area 109 can be further expanded below the area 106 and the area 108, as shown in Figure 4 , which further improves the light emitting efficiency and heat dissipation performance of the light emitting holes.

[0042] Figure 5 is another embodiment of the present application, which is different from Figure 1 in that the light emitting hole areas 106, 107, 108, 109, and the wire bonding areas 101, 102, 103, 204 are all in the same layer of the laser light source 10, i.e. there is only one layer of conductive connection layer in total, so there cannot be any intersection between different areas, otherwise it will cause series conduction and lose the function of grouping and partitioning. It can be seen that the wire bonding area 101 is composed of three separate small wire bonding areas instead of the long strip-shaped one in Figure 1 . This is done to avoid intersection conduction with the light emitting hole area 107 and the wire bonding area 102, and each small wire bonding area is electrically connected and conducted to the pad 201 of the power supply circuit through the gold wire 2010. The same situation also occurs in the wire bonding area 103. The packaging method of this embodiment realizes the partitioning of four groups of VCSEL laser light sources in only one layer of conductive connection layer, which has the advantages of one less layer of VCSEL stacking structure and simpler manufacturing process, but the disadvantage is that the spacing between the light emitting holes cannot be made smaller and denser.

[0043] It should be noted that Figure 5 the shapes of the wire bonding areas 101 to 104 and the pads 201 to 204 in the embodiment are not limited to this as shown in the figure, and different shapes can be set as needed, such as zigzag, racetrack, L-shaped, etc. The boundary shape of the light emitting hole areas 106, 107, 108, 109 can also be made as shown in Figure 3The illustrated approximate rhombus. Moreover, the four-component partitioning mode with a conductive connection layer can also be used in two-component, three-component, five-component, six-component, and other partitioning modes.

[0044] Figure 6 Another embodiment of the present application is that the laser light source 10 has a conductive connection layer, is partitioned into three components, region 106, region 107, and region 108, and the rows of light emitting holes are staggered by 1 / 3. The pads 201, 202, and 203 of the peripheral power supply circuit are arranged on different sides of the laser light source VCSEL, and the wire bonding region 102 is also changed to an L shape to enable wire bonding with the pad 202 located below. The advantage of this embodiment is that it avoids double wire bonding (also known as staggered high-low wire bonding in the industry) caused by side-by-side pads, simplifies the packaging manufacturing process of the laser light source, and improves product yield.

[0045] The above description is only a preferred embodiment of the present application and is not intended to limit the present application. Any modifications, equivalent replacements, improvements, and the like made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A laser light source partition packaging structure for a dTOF ranging system, characterized by: The light-emitting holes of the laser light source are divided into multiple groups, each group corresponds to a light-emitting area, and the number of light-emitting areas is 3 or 4 groups; Each area has several rows of light-emitting holes, and the rows of light-emitting holes in all areas are arranged periodically and interspersed; Each row of light-emitting holes is connected to a bonding area on the side of the laser light source, and the bonding area is electrically connected to the corresponding pad of the peripheral power supply circuit through a gold wire; The wiring areas connected by multiple rows of light-emitting holes belonging to the same area are connected to the same pad; Two adjacent rows of light-emitting holes are staggered. Within each row of light-emitting holes, the boundary between the two adjacent rows shrinks inward. Correspondingly, the boundary of the adjacent row of light-emitting holes is raised, complementing the shrinking position, so that the boundary of the two adjacent rows of light-emitting holes forms a complementary shape at the staggered position, where the shrinking area between the light-emitting holes in the previous row corresponds to the convex area of ​​the light-emitting holes in the next row. All bonding areas are on the same layer, with only one conductive connection layer. Some bonding areas are L-shaped, and some bonding areas are composed of multiple separate small bonding areas.

2. The laser light source partition packaging structure for a dTOF ranging system according to claim 1, characterized in that: The light-emitting surface of the laser light source is provided with an identification alignment mark and a traceability code area.

3. The laser light source partition packaging structure for a dTOF ranging system according to claim 1, characterized in that: The positions of the bonding areas connecting the light-emitting holes in different areas are staggered.

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