A multi-chip dTOF packaging structure and packaging method

Abstract

The present invention relates to a multi-chip dTOF packaging structure and a packaging method. The packaging structure includes a carrier board and an upper cover connected to the carrier board. A downward connecting portion is provided around the carrier board. An optical emission chip is provided on the carrier board. A receiving groove is also provided on the carrier board, and an optical receiving chip is provided in the receiving groove. Connecting arms adapted to the connecting portion extend downward around the upper cover. A light filtering area and a shielding area are provided on the upper cover. The light filtering area includes an emission light passing area corresponding to the optical emission chip and a reflected light passing area corresponding to the optical receiving chip. A blocking structure for separating the emission light passing area and the reflected light passing area is fixedly provided inside the packaging structure. By using the carrier board with a receiving groove to accommodate the optical receiving chip, a staggered layer is formed between the optical emission chip and the optical receiving chip, reducing the interference between light emission and light reception. Moreover, the integrated design of the upper cover reduces the product thickness, increases the wire bonding space, and improves the overall yield of the product.

Description

Technical Field

[0001] The present invention relates to the technical field of miniature module dTOF packaging, and particularly to a multi-chip dTOF packaging structure and a packaging method thereof. Background Art

[0002] The direct time of flight (dTOF) method measures the distance between the object to be measured (or the detection area of the object to be measured) and the sensor by measuring the time interval t (commonly known as the pulse ranging method) from the emission to the reception of the pulse signal emitted by the measuring instrument.

[0003] In the dTOF packaging structure, the light-emitting chip (VCSEL Die) and the light-receiving chip (Sensor Die) are two important optical components. During operation, the two components cooperate with each other. The light-emitting chip emits light to the object, and the light-receiving chip receives the light reflected by the object, so as to calculate the distance between the object to be measured and the sensor according to the time interval from emission to reception. For the existing multi-chip dTOF packaging structure, see Figure 1 which includes a carrier board 1, a light-emitting chip 2 and a light-receiving chip 3 mounted on the carrier board, and an upper cover 5 provided with a light-emitting light passing hole 501 and a reflected light passing hole 502, and a filter 7 covering the light-emitting light passing hole 501 and the reflected light passing hole 502 is provided below the light-emitting light passing hole 501 and the reflected light passing hole 502.

[0004] Among them, when the light-emitting light passing hole and the reflected light passing hole on the upper cover where the filter needs to be mounted are made by the hole forming process, burrs are easily generated, which affects the light passing function. And when the filter is mounted on the upper cover, glue overflow is likely to occur and contaminate the light passing hole, resulting in poor appearance and low yield. In addition, the partition structure of the upper cover is integrally formed with the upper cover, which makes the mold opening process of the upper cover complex, the production efficiency of the product is low, and the dispensing at the partition structure is relatively complex, which is likely to cause glue overflow problems, affecting the adjacent circuits and the photosensitive area on the light-receiving chip, or due to the dispensing process problem, the middle partition is not sealed and light transmission occurs, affecting the product function; at the same time, the wire bonding space of the product is compact and the overall thickness is relatively thick. Summary of the Invention

[0005] The technical problem solved by the present invention is to provide a multi-chip dTOF packaging structure and a packaging method for the corresponding packaging structure with high production efficiency, stable product quality and high reliability.

[0006] To solve the above technical problems, the present invention provides the following technical solutions:

[0007] The first aspect of the present application provides a multi-chip dTOF packaging structure, including: a carrier board and an upper cover connected to the carrier board. An optical emission chip is disposed on the carrier board, and a receiving groove is also provided on the carrier board. An optical receiving chip is disposed in the receiving groove; a downwardly recessed connecting portion is provided around the carrier board, and connecting arms adapted to the connecting portion are provided by downward extension around the upper cover; a filter region and a shielding region are provided on the upper cover. The filter region includes an emission light passing region corresponding to the optical emission chip and a reflected light passing region corresponding to the optical receiving chip, and a blocking structure for separating the emission light passing region and the reflected light passing region is fixedly disposed inside the packaging structure.

[0008] Further, the upper cover is integrally formed and made of glass material. An AR anti-reflection film is plated on the outer surface of the filter region, and an IR infrared cut-off film is plated on the inner surface.

[0009] Further, the shielding region is a metal layer plated on the surface of the upper cover. The copper layer is exposed on the side surface of the carrier board at the stepped connecting portion, and the copper layer includes a ground wire for electrostatic protection. After the upper cover is embedded in the carrier board at the stepped connecting portion, the metal layer is connected to the carrier board ground wire.

[0010] Further, the cross-sections of the emission light passing region and the reflected light passing region gradually decrease from top to bottom.

[0011] Further, the optical receiving chip is mounted in the receiving groove by a DAF film. After mounting, the surface of the optical receiving chip does not exceed the upper surface of the carrier board.

[0012] Further, the blocking structure is mounted on the optical receiving chip by a DAF film.

[0013] Further, the optical emission chip is mounted on the carrier board by glue, and the pads of the optical emission chip are welded and conducted with the carrier board pads by gold wires.

[0014] Further, the connecting arms of the upper cover and the connecting portion of the carrier board are fixedly connected by glue.

[0015] The second aspect of the present application provides a multi-chip dTOF packaging method for preparing the above-mentioned chip packaging structure, including the following steps:

[0016] Step a: Mount the optical emission chip on the carrier board;

[0017] Step b: Mount the optical receiving chip in the receiving groove of the carrier board;

[0018] Step c: Mount the blocking structure on the surface of the optical receiving chip between the emission light passing region and the reflected light passing region;

[0019] Step d: Use gold wires to weld and conduct the pads of the light-emitting chip and the light-receiving chip to the carrier board pads respectively;

[0020] Step e: Apply glue in the connection area of the carrier board to fixedly connect the upper cover and the carrier board.

[0021] Furthermore, the blocking structure is mounted on the surface of the light-receiving chip by a DAF film.

[0022] Advantages of the present invention:

[0023] In the present invention, the carrier board with a receiving groove accommodates the light-receiving chip, so that a staggered layer is formed between the light-emitting chip and the light-receiving chip. In the horizontal direction, infrared rays will not interfere with the light-receiving chip receiving the reflected light, reducing the interference between light emission and reception.

[0024] The upper cover adopts an integrated design, with a light filtering area and a shielding area. The shielding area adopts a metal plating process. After the upper cover is covered and fixed with the carrier board, the shielding area of the upper cover is connected to the ground wire of the carrier board, enabling the product to have a good shielding function. The light filtering area adopts an internal and external coating process, eliminating the light filter upper cover process, solving the problems of complex light filter dispensing and offset, improving efficiency and yield. At the same time, the integrated design reduces the product thickness and increases the WB wire bonding space.

[0025] In addition, the blocking area adopts a DAF mounting process, which will not cause pollution problems to the photosensitive area of the light-receiving chip, improving efficiency and yield. And when the upper cover and the carrier board are connected, an embedded connection is formed through the design of the connection part and the connection arm, with high product reliability. Description of the Drawings

[0026] Figure 1 It is a schematic diagram of a multi-chip dTOF packaging structure in the prior art;

[0027] Figure 2 It is a schematic diagram of mounting a light-emitting chip on the carrier board in this embodiment;

[0028] Figure 3 It is a schematic diagram of mounting a light-receiving chip in the receiving groove of the carrier board in this embodiment;

[0029] Figure 4 It is a schematic diagram of mounting the blocking structure in this embodiment;

[0030] Figure 5 It is a schematic diagram of welding and conducting the pads of the light-emitting chip and the light-receiving chip to the carrier board pads with gold wires in this embodiment;

[0031] Figure 6 It is a schematic diagram of fixing the upper cover and the carrier board with glue in this embodiment;

[0032] Figure 7Schematic flow diagram of the multi-chip dTOF packaging method of the present invention.

[0033] Description of reference numerals:

[0034] 1 - Carrier board; 11 - Accommodating groove; 12 - Connection part; 13 - Glue; 2 - Light-emitting chip; 3 - Light-receiving chip; 4 - Blocking structure; 5 - Upper cover; 51 - Transmitted light passing area; 52 - Reflected light passing area; 501 - Transmitted light passing hole; 502 - Reflected light passing hole; 53 - Connection arm; 6 - Gold wire; 7 - Filter film. Detailed implementation manners

[0035] To further understand the present invention, the preferred implementation manners of the present invention will be described below in conjunction with specific embodiments. However, it should be understood that these descriptions are only for further explaining the features and advantages of the present invention, rather than limiting the claims of the present invention.

[0036] It should be noted that the term "including" and any related variations in the specification and claims of the present invention are intended to cover non-exclusive inclusion. For example, a process, method, system, product or device that includes a series of steps or units is not limited to the listed steps or units, but may optionally further include steps or units not listed, or may optionally further include other steps or units inherent to these processes, methods, products or devices.

[0037] The present invention relates to the technical field of micro-module dTOF packaging. Refer to Figures 2 - 6 , and provides a multi-chip dTOF packaging structure. The carrier board 1 with the accommodating groove 11 accommodates the light-receiving chip 3, so that a staggered layer is formed between the light-emitting chip 2 and the light-receiving chip 3. In the horizontal direction, infrared rays will not interfere with the light-receiving chip 3 receiving the reflected light, reducing the interference between light emission and reception.

[0038] The upper cover 5 adopts an integrated design, increasing the wire bonding space of WB (Wire Bonding) and reducing the product thickness. The original product thickness is about 1.0 mm, and the thickness of the technical product corresponding to the present invention can generally reach about 0.6 mm, improving the overall yield of the product. At the same time, it has a light filtering and shielding function. The shielding area adopts a metal plating process, making the product have a good shielding function. The light filtering area adopts an internal and external coating process, canceling the light filtering film upper cover process, solving the problems of complex dispensing and offset of the light filtering film, and improving the efficiency and yield. The specific technical solutions are as follows:

[0039] The multi-chip dTOF packaging structure includes a carrier board 1 and an upper cover 5 connected to the carrier board 1. A receiving groove 11 is further provided on the carrier board 1, and a light receiving chip 3 is arranged in the receiving groove 11. The depth range of the groove 11 is 135+ / -5um, the thickness of the light receiving chip 3 is 100+ / -5um, and the thickness of the DAF film is 25um. The light receiving chip 3 is fixed in the receiving groove 11 of the carrier board 1 by mounting the DAF film. After mounting, the upper surface of the light receiving chip 3 does not exceed the upper surface of the carrier board 1. A light emitting chip 2 is further provided on the carrier board 1, and the light emitting chip 2 is mounted on the carrier board 1 by glue. In this embodiment, the glue is CT220HK-S1. The light emitting chip 2 and the light receiving chip 3 are respectively welded and conducted with their respective pads and the pads of the carrier board 1 through gold wires 6. The light receiving chip 3 located in the receiving groove 11 and the light emitting chip 2 located on the upper surface of the carrier board 1 form a staggered layer, and infrared rays will not interfere with the light receiving chip 3 receiving the reflected light in the horizontal direction, reducing the interference between light emission and reception.

[0040] A downward stepped connecting portion 12 is provided around the carrier board 1. In this embodiment, the depth of the stepped connecting portion 12 is 0.12 mm and the width is 0.2 mm. A connecting arm 53 adapted to the connecting portion is extended downward around the upper cover 5. The connecting arm 53 of the upper cover 5 and the connecting portion 12 of the carrier board 1 are fixedly connected by non-conductive glue, and their connection is an embedded connection. The stepped design of the connecting portion 12 increases the bonding area of the non-conductive glue and enhances the reliability of the product. And the stepped design makes it easy to control the dispensing operation, avoiding the glue from flowing, so that when the upper cover 5 is closed, the glue overflows and flows a long distance into the packaging structure, affecting the circuit and reducing the product quality.

[0041] The upper cover 5 is integrally formed and made of glass material. An emission light passing area 51 corresponding to the light emitting chip 2 and a reflected light passing area 52 corresponding to the light receiving chip 3 are provided on the upper cover 5, reducing the product thickness and increasing the WB wire bonding space, and improving the overall yield of the product. The cross-sections of the emission light passing area 51 and the reflected light passing area 52 gradually decrease from top to bottom, facilitating the laser emission of the light emitting chip 2 and the light receiving chip 3 to perceive and receive light in a larger range.

[0042] The light-emitting light-transmitting area 51 and the reflected-light light-transmitting area 52 are light-filtering areas, which ensure the emission and reception of light of corresponding wavelengths. The outer surfaces of the light-filtering areas are coated with AR anti-reflection films, and the inner surfaces are coated with IR infrared cut-off films, ensuring that only light with the same wavelength as the emission light source can enter the encapsulation structure and be sensed by the light-receiving chip 3, suppressing incoherent light sources and reducing noise interference. In this embodiment, the carrier board 1 is a multi-layer structure, generally with 2-4 circuit layers. The copper layer is exposed on the side surface of the carrier board 1 at the stepped connecting portion 12, and the copper layer contains a ground wire for electrostatic protection ESD (Electro-Static Discharge). The upper cover 5 is provided with a shielding area by applying a metal coating on the surface. After the upper cover and the carrier board are covered and fixed, the shielding area is connected to the carrier board ground wire at the stepped connecting portion 12, enabling the product to have good shielding function, reducing signal attenuation and electromagnetic interference radiation, thereby increasing signal stability and making the measured distance more accurate. The stability is improved by about 30%, physical damage can be reduced, the mechanical hardness of the upper cover 5 can be increased, and the reliability of the product can be improved; in addition, the ESD electrostatic discharge performance of the product can be increased.

[0043] In this embodiment, the upper cover 5 is integrally formed, and the light-filtering area and the shielding area are constructed by a film coating technology. Compared with the hole forming process, the one-piece forming manufacturing process of the blocking structure, and the process of covering the light-filtering film on the upper cover 5 in the prior art, the processing technology is simple, the processing cycle is shortened. It not only avoids problems such as burrs and poor forming during hole forming, which affect the light transmission effect, but also avoids the complex process of die manufacturing for the blocking structure of the upper cover, the long production cycle and high cost. At the same time, the process of covering the light-filtering film is saved, and the problem of glue overflow and pollution of the light-filtering area during the glue mounting of the light-filtering film is avoided, reducing the product size and thinning the product thickness.

[0044] The light-receiving chip 3 includes a light-emitting light-receiving area and a reflected-light light-receiving area. The light-emitting light-receiving area is used to receive the infrared laser of the corresponding wavelength that is emitted by the light-emitting chip and refracted back by the upper cover. The reflected-light light-receiving area is used to receive the infrared laser of the corresponding wavelength that is reflected by the target object. The reflected-light light-receiving area is located directly below the reflected-light light-transmitting area 52. A blocking structure 4 connecting the upper cover 5 and the light-receiving chip 3 is provided between the light-emitting light-receiving area and the reflected-light light-receiving area on the light-receiving chip 3. The blocking structure 4 is made of liquid crystal polymer 350LCP MGC350 material, with high strength, high rigidity, and good light-blocking effect. It is mounted on the light-receiving chip 3 through a DAF film, which is efficient and fast and avoids the problem of contaminating the photosensitive area, improving production efficiency and product yield. The product calculates the target distance through the time interval between emitting infrared laser and receiving infrared laser, that is, the time difference between the light-emitting light-receiving area and the reflected-light light-receiving area on the light-receiving chip 3 sensing the infrared laser.

[0045] The present invention also provides a multi-chip dTOF packaging method for preparing the above packaging structure. Refer to Figure 7 , which specifically includes:

[0046] Step a: Mount the light-emitting chip 2 on the carrier board 1;

[0047] The light-emitting chip 2 is fixed on the carrier board 1 through CT220HK-S1 type glue, and the light-emitting area is reserved on the front side;

[0048] Step b: Mount the light-receiving chip 3 in the receiving groove 11 of the carrier board 1; [[ID=!3]]

[0049] The light-receiving chip 3 is fixed in the receiving groove 11 of the carrier board 1 by mounting the DAF film, and the light-receiving area is reserved on the front side. After mounting, the surface of the light-receiving chip 3 does not exceed the upper surface of the carrier board 1;

[0050] Step c: Mount the blocking structure 4 on the surface of the light-receiving chip 3 located between the transmitting light passing area 51 and the reflected light passing area 52.

[0051] The blocking structure 4 is mounted using the DAF film. The blocking structure 4 isolates the transmitting light passing area 51 and the reflected light passing area 52, making the measurement result more reliable.

[0052] Step d: Weld and conduct the pads of the light-emitting chip 2 and the light-receiving chip 3 to the pads of the carrier board 1 through the gold wire 6.

[0053] Step e: Apply glue in the connection part area of the carrier board 1 to fixedly connect the upper cover and the carrier board.

[0054] The downward stepped connection part 12 provided on the carrier board 1 and the connection arm 53 of the upper cover 5 adapted thereto make the connection between the upper cover 5 and the carrier board 1 an embedded connection, increasing the bonding surface of the glue 13 and improving the reliability of the product. In this embodiment, AD-1300A (EICT) type glue is used at the connection part 12, and it has good sealing performance and corrosion resistance.

[0055] It should be noted that the steps in the above method can be executed sequentially, or the order of the steps can be changed or new operation steps can be added without conflict. For example, steps a and b can be interchanged under the allowable process conditions without affecting the subsequent steps. In actual process production, the process flow should be selected and adjusted in a timely manner according to actual needs.

[0056] The description of the above embodiments is only used to help understand the method and its core idea of the present invention. It should be pointed out that for those of ordinary skill in the art in this technical field, without departing from the principle of the present invention, several improvements and modifications can be made to the present invention, and these improvements and modifications also fall within the protection scope of the claims of the present invention.

Claims

1. A multi-chip dTOF packaging structure, characterized in that, It includes a carrier board (1) and an upper cover (5) connected to the carrier board; The upper cover is integrally formed and made of glass material; a light filtering area and a shielding area are provided on the upper cover. The light filtering area includes a transmitted light passing area (51) corresponding to the light emitting chip and a reflected light passing area (52) corresponding to the light receiving chip; an AR anti-reflection film is plated on the outer surface of the light filtering area, and an IR infrared cut-off film is plated on the inner surface; The shielding area is that a first metal layer is plated on the surface of the upper cover, and the second layer is exposed on the side surface of the carrier board at the stepped connecting portion. The second layer on the carrier board contains a ground wire for electrostatic protection. After the upper cover is embedded into the carrier board at the stepped connecting portion, the first metal layer is connected to the ground wire of the carrier board; metal layer, and the second metal layer on the carrier board contains a ground wire for electrostatic protection. After the upper cover is embedded into the carrier board at the stepped connecting portion, the first metal layer is connected to the ground wire of the carrier board; A light emitting chip (2) is provided on the carrier board, and a receiving groove (11) is also provided on the carrier board. A light receiving chip (3) is provided in the receiving groove; the light receiving chip is mounted in the receiving groove through a DAF film. After mounting, the surface of the light receiving chip does not exceed the upper surface of the carrier board; A connecting portion (12) that is recessed downward is provided around the carrier board, and connecting arms (53) adapted to the connecting portion are provided by downward extension around the upper cover; A blocking structure (4) for partitioning the transmitted light passing area and the reflected light passing area is fixedly provided inside the packaging structure.

2. The multi-chip dTOF package structure according to claim 1, wherein The cross-sections of the transmitted light passing area and the reflected light passing area gradually decrease from top to bottom.

3. The multi-chip dTOF packaging structure according to claim 1, characterized in that, The blocking structure is mounted on the light receiving chip through a DAF film.

4. The multi-chip dTOF package structure according to claim 1, characterized in that, The light emitting chip is mounted on the carrier board through glue, and the pads of the light emitting chip and the carrier board pads are welded and conducted through a gold wire (6).

5. The multi-chip dTOF package structure according to claim 1, characterized in that, The connecting arms of the upper cover and the connecting portion of the carrier board are fixedly connected through glue.

6. A multi-chip dTOF packaging method, characterized in that, For preparing the multi-chip dTOF packaging structure according to any one of claims 1-5, it includes the following steps: Step a: Mount the light emitting chip on the carrier board; Step b: Mount the light receiving chip in the receiving groove of the carrier board; Step c: Mount the blocking structure on the surface of the light receiving chip between the transmitted light passing area and the reflected light passing area; Step d: Weld and conduct the pads of the light emitting chip and the light receiving chip to the carrier board pads respectively through gold wires; Step e: Apply glue in the connecting portion area of the carrier board to fixedly connect the upper cover and the carrier board.

7. The multi-chip dTOF packaging method according to claim 6, wherein The blocking structure is mounted on the surface of the light receiving chip through a DAF film.

Images