A light sensor package structure and a manufacturing method thereof

Abstract

The present application relates to the technical field of component packaging, in particular to a light sensor packaging structure and a preparation method thereof, the packaging structure comprising a pre-molded substrate, the pre-molded substrate having a groove; a sensing chip arranged in the groove, the upper surface of the sensing chip having a light sensing area; a light shielding layer filled between the side surface of the sensing chip and the inner side wall of the groove, the light shielding layer covering at least part of the side surface of the sensing chip, and the upper surface of the light shielding layer being not higher than the upper surface of the light sensing area; and a transparent sealing layer filled in the groove and covering at least the upper surface of the light shielding layer and the upper surface of the light sensing area. Through the above arrangement, the performance of the packaging structure is significantly improved, and the signal-to-noise ratio of the sensor is improved.

Description

Technical Field

[0001] This invention relates to the field of component packaging technology, and in particular to a photosensor packaging structure and its fabrication method. Background Technology

[0002] In existing photosensor packaging structures, the sensing chip (IC) is typically mounted on a planar substrate, wire bonded around the sensing chip, and then encapsulated with a transparent encapsulation layer. However, when the photosensor is operating, ambient light or stray light can penetrate the transparent encapsulation layer and enter the chip from its side surface, especially into the logic circuit area or non-photosensitive area. This generates photocurrent, resulting in optical noise in the sensor's output signal, which severely affects the sensor's signal-to-noise ratio (SNR) and detection accuracy. Summary of the Invention

[0003] This invention provides a photosensitive sensor packaging structure and fabrication method, which can solve at least one problem in the background art to improve the performance of the packaging structure and significantly improve the signal-to-noise ratio of the sensor.

[0004] This invention provides a photosensitive sensor packaging structure, comprising: A pre-molded substrate having a groove; A sensing chip is disposed in the groove, and the upper surface of the sensing chip has a photosensitive area; A light-shielding layer is filled between the side surface of the sensing chip and the inner sidewall of the groove. The light-shielding layer covers at least a portion of the side surface of the sensing chip, and the upper surface of the light-shielding layer is not higher than the upper surface of the photosensitive area. A transparent sealing layer is filled into the groove, covering at least the upper surface of the light-shielding layer and the upper surface of the photosensitive area.

[0005] Furthermore, the pre-molded substrate includes a metal lead frame and a molding compound covering at least a portion of the metal lead frame, the metal lead frame being exposed at the bottom of the groove to support the sensing chip.

[0006] Furthermore, it also includes metal wires, the sensing chip is electrically connected to the metal lead frame through the metal wires, and the light-shielding layer also covers the connection between the metal wires and the solder pads of the sensing chip; and the solder pads are located at the periphery of the upper surface of the sensing chip and are spaced apart from the photosensitive area.

[0007] Furthermore, the light-shielding layer completely covers the entire side surface of the sensing chip.

[0008] Furthermore, the coverage height h1 of the light-shielding layer covering the side surface of the sensing chip is 50% to 90% of the thickness H of the sensing chip.

[0009] Furthermore, on at least one side of the sensor chip side surface, the coverage height h1 of the light-shielding layer covering the sensor chip side surface is greater than the coverage height h2 covering one side of the inner wall of the groove.

[0010] Furthermore, on at least one side of the sensor chip side surface, the upper surface of the light-shielding layer gradually decreases from the side closer to the sensor chip towards the side closer to the inner wall of the groove.

[0011] Furthermore, the depth h3 of the groove is less than or equal to the thickness H of the sensing chip, and the top of the inner sidewall of the groove is lower than or flush with the upper surface of the sensing chip.

[0012] This invention also provides a method for fabricating a photosensor packaging structure, comprising the following steps: A pre-molded substrate is provided, the pre-molded substrate having a groove; The sensing chip is fixed in the groove, and the upper surface of the sensing chip has a photosensitive area; and the sensing chip is electrically connected to the metal lead frame in the pre-molded substrate by a metal wire. A light-shielding layer is filled between the side surface of the sensing chip and the inner sidewall of the groove. The light-shielding layer covers at least a portion of the side surface of the sensing chip and the connection between the metal wire and the bonding pad of the sensing chip. The upper surface of the light-shielding layer is not higher than the upper surface of the photosensitive area. A transparent sealing layer is filled into the groove, and at least covers the upper surface of the light-shielding layer and the upper surface of the photosensitive area.

[0013] Furthermore, when filling the light-shielding layer, the flow range of the light-shielding layer is limited by the surface tension of the light-shielding layer itself and the inner sidewall of the groove, so that the coverage height h1 of the light-shielding layer covering the side surface of the sensing chip is greater than the coverage height h2 covering one side of the inner sidewall of the groove, and the upper surface of the light-shielding layer forms an arc-shaped concave surface, an arc-shaped convex surface, or an inclined surface.

[0014] Based on the above, the photosensor packaging structure provided by the present invention, compared with the prior art, forms a groove by forming a pre-molded substrate. The physical boundary of the groove effectively limits the flow range and filling height of the light-shielding layer, avoiding the risk of the light-shielding layer overflowing into the photosensitive area and improving product yield. At the same time, the light-shielding layer is precisely filled between the side surface of the sensing chip and the inner sidewall of the groove, which can effectively cover the side surface of the sensing chip to cut off the lateral incident path of stray light and prevent stray light from entering the chip from the side surface of the chip to generate photocurrent, thereby significantly reducing optical noise and improving the signal-to-noise ratio of the sensor.

[0015] Based on this, a transparent sealing layer covers the upper surface of the light-shielding layer and the photosensitive area, which not only ensures the smooth light path of the photosensitive area, but also achieves sealed protection for the light-shielding layer and the sensing chip, so that the product has both good optical performance and structural reliability.

[0016] Other features and beneficial effects of the invention will be set forth in the following description, and will be apparent in part from the description, or may be learned by practicing the invention. Attached Figure Description

[0017] To more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the drawings used in the description of the embodiments or the prior art will be briefly introduced below. Obviously, the drawings described below are some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0018] Figures 1-6 Schematic diagrams of different variations of the photosensor packaging structure provided in the embodiments of the present invention; Figure 7 This is a schematic cross-sectional view of the assembly of a method for fabricating a photosensor packaging structure provided in an embodiment of the present invention.

[0019] Explanation of reference numerals in the attached figures: 10. Pre-molded substrate; 11. Metal lead frame; 12. Molded enclosure; 13. Groove; 13a. Inner sidewall; 20. Sensing chip; 20a. Side surface; 21. Photosensitive area; 30. Light-shielding layer; 40. Transparent sealing layer; 50. Metal wire. Detailed Implementation

[0020] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. The technical features designed in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other. All other embodiments obtained by those skilled in the art based on the embodiments of the present invention without creative effort are within the scope of protection of the present invention.

[0021] In the description of this invention, it should be noted that all terms used in this invention (including technical and scientific terms) have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains, and should not be construed as limiting the invention; it should be further understood that the terms used in this invention should be understood to have the same meaning as those in the context of this specification and in the relevant field, and should not be understood in an idealized or overly formal sense, except as expressly defined in this invention.

[0022] Currently, most optical sensing element packaging technologies (such as ambient light sensors or proximity sensors) use planar substrates (such as PCBs or BT substrates) to carry the sensing chip and cover it with transparent encapsulant for protection. However, in actual use, ambient light or stray light can easily penetrate the transparent encapsulant and enter the chip from the side surface, especially into the logic circuit area or non-photosensitive area (such as the wire bonding area), thereby generating photocurrent and causing optical noise in the sensor output signal, which seriously affects the sensor's signal-to-noise ratio and detection accuracy. To solve the problem of lateral light leakage, some existing technologies attempt to place black glue or light-shielding walls around the chip. However, due to the lack of effective boundary constraints on planar substrates, the black glue is prone to overflow during the filling process, contaminating the photosensitive area on the top of the chip and leading to a decrease in product yield.

[0023] To address the technical problems in existing photosensor packaging structures, such as lateral stray light easily entering the chip and generating optical noise, and the lack of effective boundary constraints during the filling process of the light-shielding layer leading to overflow and contamination of the photosensitive area, resulting in decreased yield, this invention provides a photosensor packaging structure. A groove is formed by a pre-molded substrate, and the physical boundary of the groove precisely limits the filling range and height of the light-shielding layer. This prevents the light-shielding layer from overflowing into the photosensitive area while effectively blocking lateral stray light, significantly reducing optical noise and improving product yield.

[0024] The following detailed description is provided in conjunction with specific embodiments and accompanying drawings.

[0025] Example 1 Please see Figures 1-6 This invention provides a photosensitive sensor packaging structure, which includes at least: a pre-molded substrate 10, a sensing chip 20, a light-shielding layer 30, and a transparent sealing layer 40.

[0026] In a specific implementation, the pre-molded substrate 10 has a groove 13, which is formed by recessing inward from the upper surface of the pre-molded substrate 10. This groove 13 provides a space and physical boundary for the sensing chip 20 and subsequent filling materials. The groove 13 can be formed directly as a single piece during the injection molding process of the pre-molded substrate 10, or it can be formed after the pre-molded substrate 10 is formed by machining or etching. The specific method can be reasonably selected according to the actual manufacturing process, and this embodiment does not limit it. The pre-molded substrate 10 adopts a pre-molded lead frame structure, and its groove 13 is formed during injection molding. If additional barriers are made on the substrate or a special mold is used to restrict the flow of the light-shielding layer 30, this will increase the process complexity and packaging cost, which is not conducive to the thinning and cost reduction of the product. Therefore, by having a structure with groove 13 directly in the pre-molded substrate 10, there is no need to build additional barriers or use a special mold, which is beneficial to simplify the process and reduce packaging costs.

[0027] A sensing chip 20 is disposed within a recess 13, and the upper surface of the sensing chip 20 has a photosensitive area 21. It should be understood that the photosensitive area 21 is the functional area of ​​the sensing chip 20 used to receive external light and perform photoelectric conversion. The sensing chip 20 can be an ambient light sensing chip, a proximity sensing chip, or other types of optical sensing chips. The sensing chip 20 can be fixed to the bottom of the recess 13 using an adhesive (such as non-conductive adhesive), the thickness of which can be adjusted according to the actual chip size and process requirements.

[0028] The light-shielding layer 30 is filled between the side surface 20a of the sensing chip 20 and the inner sidewall 13a of the groove 13. The light-shielding layer 30 covers at least a portion of the side surface 20a of the sensing chip 20, and the upper surface of the light-shielding layer 30 is not higher than the upper surface of the photosensitive area 21.

[0029] Preferably, the light-shielding layer 30 can be black epoxy resin, black silicone or other colloidal materials with light-shielding function (hereinafter referred to as black glue), which absorbs or blocks stray light incident from the side, and prevents stray light from entering the logic circuit area or non-photosensitive area inside the chip from the side surface 20a of the sensing chip 20 to generate photocurrent.

[0030] As an example, the upper surface of the light-shielding layer 30 is not higher than the upper surface of the photosensitive area 21. That is, the upper surface of the light-shielding layer 30 can be lower than the upper surface of the photosensitive area 21 or flush with the upper surface of the photosensitive area 21, thereby ensuring that the light-shielding layer 30 will not cover or contaminate the photosensitive area 21, and ensuring that the photosensitive area 21 can normally receive external incident light.

[0031] The light-shielding layer 30 covers at least a portion of the side surface 20a of the sensing chip 20. It can completely cover the entire side surface or cover the main area of ​​the side surface (the lower half) to cut off the lateral incident path of stray light. In addition, the light-shielding layer 30 fills the gap between the side surface 20a of the sensing chip 20 and the inner sidewall 13a of the groove 13, which also provides secondary protection and curing for the chip side and wire bonding joints, thereby improving the product's resistance to thermal stress and moisture.

[0032] A transparent sealing layer 40 is filled within the groove 13, covering at least the upper surface of the light-shielding layer 30 and the upper surface of the photosensitive area 21. As an example, the transparent sealing layer 40 is a light-transmitting material (such as transparent epoxy resin, transparent silicone, etc.), covering the photosensitive area 21 to protect it and ensure that external light can pass through the transparent sealing layer 40 to reach the photosensitive area 21. Simultaneously, the transparent sealing layer 40 covers the upper surface of the light-shielding layer 30 to seal and protect it, preventing the light-shielding layer 30 from aging or peeling off due to external environmental corrosion, thus improving the long-term reliability of the product. The transparent sealing layer 40 can be filled into the groove 13 using dispensing or injection molding processes.

[0033] It should be noted that the number of grooves 13 and the number and type of sensing chips 20 in this embodiment are merely exemplary classification methods. Those skilled in the art can reasonably adjust the number of grooves and chip types according to actual product design requirements (such as multi-sensor chip integration, collaborative operation of sensing chips and light-emitting chips, etc.), all of which fall within the protection scope of this invention.

[0034] Optionally, the pre-molded substrate 10 includes a metal lead frame 11 and a molding compound 12 covering at least a portion of the metal lead frame 11, with the metal lead frame 11 exposed at the bottom of the recess 13 to carry the sensing chip 20.

[0035] In a specific implementation, the pre-mold substrate 10 consists of a metal leadframe 11 and a molding compound 12. The molding compound 12 covers at least a portion of the metal leadframe 11, while the middle area of ​​the metal leadframe 11 is exposed to the bottom of the groove 13, thus forming a support surface for carrying the sensing chip 20. This pre-mold structure is integrally formed through injection molding, and the groove 13 is formed during injection molding. The manufacturing process is mature, the structure is stable and reliable, and there is no need to construct additional barriers in subsequent processes. The metal leadframe 11 can be made of copper, copper alloy, or other conductive metal materials, and the molding compound 12 can be made of epoxy resin molding compound or other insulating encapsulation materials. It should be understood that the metal leadframe 11 is not only used to carry the sensing chip 20, but also to realize the electrical connection between the sensing chip 20 and external circuits. The bottom or side of the metal leadframe 11 can be further formed with pins or pads for connection with external circuit boards.

[0036] By utilizing the physical boundary formed by the groove 13 structure designed by the pre-molded substrate 10 itself, which is composed of metal lead frame 11 and molding body 12, to restrict the flow of the light shielding layer 30 during filling, the problem that traditional planar packaging easily leads to the light shielding layer 30 contaminating the photosensitive area is solved, and the production yield is improved.

[0037] Optionally, it also includes a metal wire 50, through which the sensing chip 20 is electrically connected to the metal lead frame 11. The light-shielding layer 30 also covers the connection between the metal wire 50 and the solder pad of the sensing chip 20; and the solder pad is located at the periphery of the upper surface of the sensing chip 20 and is spaced apart from the photosensitive area 21.

[0038] In specific implementation, the upper surface of the sensing chip 20, in addition to the photosensitive area 21, is also provided with solder pads (wire bonding joints, not shown in the figure). These solder pads are distributed around the periphery of the photosensitive area 21, meaning there is a certain distance between the area where the solder pads are located and the photosensitive area 21. This distance is used to isolate the wire bonding area from the photosensitive area, preventing mechanical damage or contamination to the photosensitive area during the wire bonding process. One end of the metal wire 50 is connected to the solder pad of the sensing chip 20, and the other end is connected to the metal lead frame 11, thereby achieving electrical conductivity between the sensing chip 20 and the metal lead frame 11. It should be understood that the metal wire 50 can be made of gold wire, copper wire, or alloy wire, and the connection is achieved through wire bonding. The light-shielding layer 30 covers not only the side surface 20a of the sensing chip 20 but also the connection point (i.e., the wire bonding joint area) between the metal wire 50 and the solder pad of the sensing chip 20. By covering the wire bonding solder joint area with a 30mm light-shielding layer, the design provides secondary protection and curing for the solder joint area, improving the mechanical strength and thermal stress resistance of the solder joint connection, and enhancing the product's moisture resistance and long-term reliability.

[0039] Optionally, such as Figure 1 , Figures 4-6 The light-shielding layer 30 completely covers the entire side surface 20a of the sensing chip 20.

[0040] In specific implementation, the light-shielding layer 30 completely covers all the side surfaces 20a of the sensing chip 20. That is, the light-shielding layer 30 forms a complete ring-shaped covering structure around the four side surfaces of the sensing chip 20, achieving 100% optical shielding of the side surfaces of the sensing chip 20. This can completely eliminate stray light entering the side surfaces of the sensing chip 20 from any direction, achieving the best lateral optical blocking effect and significantly improving the signal-to-noise ratio of the sensor.

[0041] It should be understood that when the light-shielding layer 30 completely covers the entire side surface 20a, the upper surface of the light-shielding layer 30 is still not higher than the upper surface of the photosensitive area 21. That is, although the light-shielding layer 30 completely covers the side surface, its upper surface only reaches below the photosensitive area 21 or is flush with the lower surface of the photosensitive area 21, and will not cover the photosensitive area 21.

[0042] Optionally, such as Figure 2 , Figure 3 The light-shielding layer 30 covers the side surface 20a of the sensing chip 20 with a coverage height h1 of 50% to 90% of the thickness H of the sensing chip 20.

[0043] In specific implementation, the height h1 covered by the light-shielding layer 30 along the side surface 20a of the sensing chip 20 from bottom to top is 50% to 90% of the thickness H of the sensing chip 20. It should be understood that the coverage height h1 here is the height measured upward from the lower surface of the sensing chip 20 (i.e., the bottom surface of the sensing chip 20 that contacts the bottom of the groove 13) along the side surface 20a. Setting the coverage height h1 to 50% to 90% of the chip thickness H means that the light-shielding layer 30 covers the lower half and middle area of ​​the side surface 20a, while leaving the upper half (or upper part) near the photosensitive area 21 uncovered. This partial coverage method is suitable for scenarios where the amount of adhesive dispensing needs to be precisely controlled. A coverage height h1 of not less than 50% ensures that the light-shielding layer 30 covers the wire bonding joint area (usually located in the lower half of the chip side surface), ensuring that the wire bonding joint area is effectively protected from light. The light-shielding layer 30 can ensure that it covers the chip sidewall area directly below the wire bonding joint, preventing stray light from entering the chip from the side surface of this area and generating photocurrent, thereby effectively protecting the internal logic circuit near the wire bonding area. If the coverage height h1 is not higher than 90%, a sufficient safety distance can be reserved between the upper surface of the light-shielding layer 30 and the upper surface of the photosensitive area 21, effectively reducing the risk of the light-shielding layer 30 overflowing upwards into the photosensitive area 21 during the filling process, which is conducive to improving product yield.

[0044] Optionally, such as Figures 1-5 On at least one side of the side surface 20a of the sensing chip 20, the coverage height h1 of the light-shielding layer 30 on the side surface 20a of the sensing chip 20 is greater than the coverage height h2 on one side of the inner sidewall 13a of the groove 13.

[0045] In specific implementation, on the same cross-section, the coverage height h1 of the light-shielding layer 30 on the side surface 20a of the sensing chip 20 is greater than the coverage height h2 of the light-shielding layer 30 on the inner sidewall 13a of the groove 13. That is, the upper surface of the light-shielding layer 30 is higher on the side closer to the sensing chip 20 than on the side closer to the inner sidewall 13a of the groove 13. In other words, the upper surface of the light-shielding layer 30 has a higher coverage height h1 on the side surface 20a of the sensing chip 20, and a lower coverage height h2 on the inner sidewall 13a of the groove 13. By setting h1>h2, on the one hand, the light-shielding layer 30 has a higher coverage height on the side surface 20a of the sensing chip 20, which can ensure that the light-shielding layer 30 fully covers the side surface 20a of the sensing chip 20 and effectively block stray light from entering the sensitive circuit area inside the sensing chip 20 from this area; on the other hand, the light-shielding layer 30 has a lower coverage height h2 on the inner sidewall 13a of the groove 13, which allows for a larger filling space for the transparent sealing layer 40 near the inner wall of the groove 13. This is beneficial for the transparent sealing layer 40 to flow fully into the groove 13 during subsequent filling, avoiding voids or interface delamination between the transparent sealing layer 40 and the light-shielding layer 30 due to insufficient space, thereby improving the structural integrity and sealing reliability of the package.

[0046] Optionally, such as Figures 1-5 On at least one side of the side surface 20a of the sensing chip 20, the upper surface of the light-shielding layer 30 gradually decreases from the side closer to the sensing chip 20 toward the side closer to the inner sidewall 13a of the groove 13.

[0047] In specific implementation, the upper surface of the light-shielding layer 30 is higher near the side surface 20a of the sensing chip 20 and lower near the inner sidewall 13a of the groove 13, exhibiting a continuous downward descent from the side surface 20a of the sensing chip 20 towards the inner sidewall 13a of the groove 13. It should be understood that this "gradual descent" can be a gentle slope or a continuous arc. This shape is formed naturally by utilizing the surface tension characteristics of the light-shielding layer 30 (black adhesive) itself, constrained by the physical boundaries of the groove 13. This gradual descent ensures that the height of the light-shielding layer 30 near the sensing chip 20 effectively covers the chip side surface and wire bonding area, while the lower height near the inner sidewall 13a of the groove provides better filling space for the transparent sealing layer 40. This shape itself also reflects that the filling process of the light-shielding layer 30 is effectively guided and restricted by the physical boundary of the groove 13. The height of the light-shielding layer 30 is precisely controlled by the synergistic effect of the surface tension of the light-shielding layer 30 and the shape of the groove 13. The light-shielding layer 30 can be prevented from overflowing into the photosensitive area 21 without the need for additional baffles, thus simplifying the manufacturing process.

[0048] Optionally, such as Figures 1-5 Combination Figure 7 The depth h3 of the groove 13 is less than or equal to the thickness H of the sensing chip 20, and the top of the inner sidewall 13a of the groove 13 is lower than or flush with the upper surface of the sensing chip 20.

[0049] In specific implementation, such as Figure 6 As shown, when the depth h3 of the groove 13 is equal to the thickness H of the sensing chip 20, the top of the inner sidewall 13a of the groove 13 is flush with the upper surface of the sensing chip 20. At this time, the sidewall of the groove 13 completely covers the lower half and middle part of the sensing chip 20, providing sufficient physical protection and filling space for the light-shielding layer 30. Figures 1-5 When the depth h3 of the groove 13 is less than the thickness H of the sensing chip 20, the top of the inner sidewall 13a of the groove 13 is lower than the upper surface of the sensing chip 20. That is, the upper part of the sensing chip 20 (including the photosensitive area 21) protrudes above the top of the inner sidewall 13a of the groove 13. This structure can reduce the optical obstruction of the photosensitive area 21 by the inner sidewall 13a of the groove 13, increase the light-receiving field of view of the photosensitive area 21, and improve the optical receiving efficiency of the photosensor.

[0050] It should be understood that the depth h3 of the groove 13 is the height measured from the bottom of the groove 13 (i.e., the bearing surface of the metal lead frame 11 exposed at the bottom of the groove 13) to the top of the inner sidewall 13a of the groove 13. In addition, the depth h3 of the groove 13 can also be greater than the thickness H of the sensing chip 20 (i.e., forming a deep groove protection). In this case, the top of the inner sidewall 13a of the groove 13 is higher than the upper surface of the sensing chip 20, which can provide more adequate physical protection for the sensing chip 20. However, the field of view of the photosensitive area 21 will be affected to some extent. The specific choice can be made according to the optical and protection requirements of the actual product. This embodiment does not limit this.

[0051] Optionally, the upper surface of the light-shielding layer 30 is an arc-shaped concave surface, an arc-shaped convex surface, or an inclined surface, and the lowest point or highest point of the arc-shaped concave surface or the arc-shaped convex surface is located between the side surface 20a of the sensing chip 20 and the inner sidewall 13a of the groove 13.

[0052] In practical implementation, the upper surface of the light-shielding layer 30 can be presented as an arc-shaped concave surface (e.g., Figure 4 As shown), curved convex surface (such as...) Figure 5 (as shown) or inclined plane (such as) Figure 1 (As shown) and other forms. Specifically, when the upper surface of the light-shielding layer 30 is an arc-shaped concave surface, the lowest point of the arc-shaped concave surface is located in the area between the side surface 20a of the sensing chip 20 and the inner sidewall 13a of the groove 13, that is, the upper surface of the light-shielding layer 30 exhibits a shape that is low in the middle and high on both sides. When the upper surface of the light-shielding layer 30 is an arc-shaped convex surface, the highest point of the arc-shaped convex surface is located in the area between the side surface 20a of the sensing chip 20 and the inner sidewall 13a of the groove 13, that is, the upper surface of the light-shielding layer 30 exhibits a shape that is high in the middle and low on both sides. It should be understood that the actual shape of the upper surface of the light-shielding layer 30 is affected by a variety of factors, such as the filling amount of the light-shielding layer 30, the material viscosity, the surface tension, and the size ratio of the groove 13. These different upper surface morphologies all fall within the protection scope of this invention. Their common feature is that the upper surface of the light-shielding layer 30 is not higher than the upper surface of the photosensitive area 21. That is, regardless of the specific shape of the upper surface of the light-shielding layer 30, its highest point will not exceed the upper surface of the photosensitive area 21, thereby ensuring that the photosensitive area 21 is not contaminated. Simultaneously, the upper surface of the light-shielding layer 30 is a continuous non-planar shape, which facilitates the interfacial bonding between the light-shielding layer 30 and the transparent sealing layer 40, ensuring the overall structural integrity of the package.

[0053] It should be noted that the morphology of the upper surface of the light-shielding layer 30 (such as an arc-shaped concave surface, an arc-shaped convex surface, an inclined surface, etc.) may vary depending on the filling amount, material viscosity and process parameters of the light-shielding layer 30. The specific morphologies listed in the embodiments of the present invention are for illustrative purposes only and do not constitute a limitation on the scope of protection of the present invention.

[0054] Example 2 like Figure 7 As shown, this embodiment of the invention also provides a method for fabricating a photosensor packaging structure, comprising the following steps: Step S10: Provide a pre-molded substrate 10, which has a groove 13.

[0055] The pre-plastic substrate 10 can be integrally formed by injection molding, and the groove 13 can be formed simultaneously during the injection molding process, or the groove 13 can be formed by mechanical processing after the pre-plastic substrate 10 is formed.

[0056] Step S20: Fix the sensing chip 20 in the groove 13. The upper surface of the sensing chip 20 has a photosensitive area 21.

[0057] The sensing chip 20 can be bonded and fixed to the bearing surface of the metal lead frame 11 at the bottom of the groove 13 using a non-conductive adhesive, and then cured. After the sensing chip 20 is fixed, a wire bonding process is performed to electrically connect the pads of the sensing chip 20 to the metal lead frame 11 through metal wires 50.

[0058] Step S30: A light-shielding layer 30 is filled between the side surface 20a of the sensing chip 20 and the inner sidewall 13a of the groove 13. The light-shielding layer 30 covers at least a portion of the side surface 20a of the sensing chip 20, and the upper surface of the light-shielding layer 30 is not higher than the upper surface of the photosensitive area 21.

[0059] The light-shielding layer 30 (black glue) can be injected into the gap between the side surface 20a of the sensing chip 20 and the inner sidewall 13a of the groove 13 using a dispensing machine or a spray valve. The surface tension of the light-shielding layer 30 and the physical boundary of the groove 13 are used to control the filling height and flow range of the light-shielding layer 30, ensuring that the upper surface of the light-shielding layer 30 does not exceed the upper surface of the photosensitive area 21, thus avoiding contamination of the photosensitive area 21. Simultaneously, the sidewall of the groove 13 restricts the outward diffusion of the light-shielding layer 30, achieving height control. After filling, the light-shielding layer 30 undergoes a curing process.

[0060] Step S40: Fill the groove 13 with the transparent cover layer 40, and at least cover the upper surface of the light-shielding layer 30 and the upper surface of the photosensitive area 21.

[0061] The liquid transparent sealing layer 40 material can be filled into the groove 13 by dispensing or injection molding, so that it covers the upper surface of the light-shielding layer 30 and the upper surface of the photosensitive area 21, and then cured to form the transparent sealing layer 40.

[0062] When incident light passes through the transparent sealing layer 40 and illuminates the sensing chip 20, only direct light can enter the photosensitive area 21, be received by the sensing chip 20, and be converted into an electrical signal. Obliquely incident or stray light, when illuminating the side surface 20a of the sensing chip 20, is absorbed or blocked by the light-shielding layer 30 covering the side surface 20a, preventing it from entering the logic circuit area or non-photosensitive area inside the chip to generate photocurrent. This effectively eliminates lateral optical noise and significantly improves the signal-to-noise ratio and detection accuracy of the sensor. Simultaneously, since the upper surface of the light-shielding layer 30 is not higher than the upper surface of the photosensitive area 21, the photosensitive area 21 can receive external incident light without obstruction, ensuring the normal operation of the sensing chip 20.

[0063] Optionally, after fixing the sensing chip 20 in the groove 13 and before filling the light-shielding layer 30, the sensing chip 20 is electrically connected to the metal lead frame 11 in the pre-molded substrate 10 via the metal wire 50; when filling the light-shielding layer 30, the light-shielding layer 30 simultaneously covers the connection between the metal wire 50 and the solder pad of the sensing chip 20.

[0064] In practice, after the sensing chip 20 is fixed to the bottom of the groove 13 and cured, a wire bonding process is first used to electrically connect the sensing chip 20 to the metal lead frame 11, and then the light-shielding layer 30 is filled. This process sequence of wire bonding followed by filling the light-shielding layer 30 avoids spatial interference or solder joint contamination caused by pre-filling the light-shielding layer 30. During the subsequent filling of the light-shielding layer 30, the light-shielding layer 30 covers not only the side surface 20a of the sensing chip 20, but also the sides and bottom of the connection point between the metal lead frame 50 and the pad of the sensing chip 20 (i.e., the wire bonding solder joint area). On the one hand, the light-shielding layer 30 covers the side of the solder pad, providing lateral light-shielding protection for the wire bonding area and blocking stray light from entering the chip from the chip sidewall interface adjacent to the solder pad, thus preventing stray light from inducing photocurrent in this area. On the other hand, after the light-shielding layer 30 is cured, it forms mechanical reinforcement and sealing protection for the wire bonding area, improving the mechanical strength, thermal stress resistance and moisture resistance of the solder joint connection, and enhancing the long-term reliability of the product.

[0065] Preferably, when filling the light-shielding layer 30, the surface tension of the light-shielding layer 30 itself and the inner sidewall 13a of the groove 13 limit the flow range of the light-shielding layer 30, so that the coverage height h1 of the light-shielding layer 30 covering the side surface 20a of the sensing chip 20 is greater than the coverage height h2 covering one side of the inner sidewall 13a of the groove 13, and the upper surface of the light-shielding layer 30 forms an arc-shaped concave surface, an arc-shaped convex surface, or an inclined surface.

[0066] In practice, when the light-shielding layer 30 (black glue) is injected into the gap between the side surface 20a of the sensing chip 20 and the inner wall 13a of the groove 13 using a dispensing machine or a spray valve, the light-shielding layer 30, in its liquid state, is subjected to its own surface tension, forming an arc-shaped concave surface, an arc-shaped convex surface, or an inclined surface on its upper surface. Simultaneously, the inner wall 13a of the groove 13 acts as a physical boundary, restricting the lateral flow range of the light-shielding layer 30, preventing it from spreading outwards to non-target areas, and confining its flow range within the gap between the side surface 20a of the sensing chip 20 and the inner wall 13a of the groove 13. Through the synergistic effect of the surface tension of the light-shielding layer 30 and the physical boundary of the inner wall 13a of the groove 13, precise height control of the light-shielding layer 30 can be achieved after filling without the need for additional molds or retaining structures.

[0067] Furthermore, the specific structure, function, and role of the photosensor packaging structure can be referred to the aforementioned Embodiment 1, and will not be repeated here.

[0068] In summary, the photosensor packaging structure and fabrication method provided in this embodiment, by forming a groove on a pre-molded substrate, precisely limits the filling range and height of the light-shielding layer using the physical boundary of the groove, avoiding the risk of the light-shielding layer overflowing into the photosensitive area during the filling process, and significantly improving product yield. At the same time, the light-shielding layer is precisely filled between the side surface of the sensing chip and the inner sidewall of the groove, which can effectively cover the side surface of the sensing chip to cut off the lateral incident path of stray light, isolate optical crosstalk, and prevent stray light from entering the chip from the side surface of the sensing chip to generate photocurrent, thereby significantly reducing optical noise and improving the signal-to-noise ratio and detection accuracy of the sensor. The transparent sealing layer covers the upper surface of the light-shielding layer and the upper surface of the photosensitive area, which not only ensures the unobstructed optical path of the photosensitive area, but also achieves sealed protection for the light-shielding layer and the sensing chip, so that the product has both good optical performance and structural reliability.

[0069] In addition, the light-shielding layer covering the side surface of the sensing chip and the wire bonding joints provides secondary protection and curing for the chip sides and wire bonding joints, effectively improving the product's resistance to thermal stress and moisture resistance. At the same time, there is no need to set up additional barriers or metal light shields, and the package size is not increased, which is conducive to product thinning and cost reduction.

[0070] Furthermore, those skilled in the art should understand that although many problems exist in the prior art, each embodiment or technical solution of the present invention can be improved in only one or a few aspects, without necessarily solving all the technical problems listed in the prior art or background art simultaneously. Those skilled in the art should understand that any content not mentioned in a claim should not be construed as a limitation on that claim.

[0071] Although this document frequently uses terms such as pre-molded substrate, metal lead frame, molding compound, recess, inner sidewall, sensor chip, side surface, photosensitive area, light-shielding layer, transparent encapsulation layer, and metal wire, the possibility of using other terms is not excluded. These terms are used merely for the convenience of describing and explaining the essence of the invention; interpreting them as any additional limitation would be contrary to the spirit of the invention.

[0072] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some or all of the technical features; and these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of the present invention.

Claims

1. A photosensitive sensor packaging structure, characterized in that, include: A pre-molded substrate having a groove; A sensing chip is disposed in the groove, and the upper surface of the sensing chip has a photosensitive area; A light-shielding layer is filled between the side surface of the sensing chip and the inner sidewall of the groove. The light-shielding layer covers at least a portion of the side surface of the sensing chip, and the upper surface of the light-shielding layer is not higher than the upper surface of the photosensitive area. A transparent sealing layer is filled into the groove, covering at least the upper surface of the light-shielding layer and the upper surface of the photosensitive area.

2. The photosensor packaging structure according to claim 1, characterized in that: The pre-molded substrate includes a metal lead frame and a molding compound covering at least a portion of the metal lead frame, the metal lead frame being exposed at the bottom of the groove to support the sensing chip.

3. The photosensor packaging structure according to claim 2, characterized in that: It also includes metal wires, the sensing chip is electrically connected to the metal lead frame through the metal wires, and the light-shielding layer also covers the connection between the metal wires and the solder pads of the sensing chip; and the solder pads are located at the periphery of the upper surface of the sensing chip and are spaced apart from the photosensitive area.

4. The photosensor packaging structure according to claim 1, characterized in that: The light-shielding layer completely covers the entire side surface of the sensing chip.

5. The photosensor packaging structure according to claim 1, characterized in that: The coverage height h1 of the light-shielding layer covering the side surface of the sensing chip is 50% to 90% of the thickness H of the sensing chip.

6. The photosensor packaging structure according to claim 1, characterized in that: On at least one side of the sensor chip side surface, the coverage height h1 of the light-shielding layer covering the sensor chip side surface is greater than the coverage height h2 covering one side of the inner wall of the groove.

7. The photosensor packaging structure according to claim 1, characterized in that: On at least one side of the sensor chip side surface, the upper surface of the light-shielding layer gradually decreases from the side closer to the sensor chip towards the side closer to the inner wall of the groove.

8. The photosensor packaging structure according to claim 1, characterized in that: The depth h3 of the groove is less than or equal to the thickness H of the sensing chip, and the top of the inner sidewall of the groove is lower than or flush with the upper surface of the sensing chip.

9. A method for fabricating a photosensor packaging structure, characterized in that, Includes the following steps: A pre-molded substrate is provided, the pre-molded substrate having a groove; The sensing chip is fixed in the groove, and the upper surface of the sensing chip has a photosensitive area; and the sensing chip is electrically connected to the metal lead frame in the pre-molded substrate by a metal wire. A light-shielding layer is filled between the side surface of the sensing chip and the inner sidewall of the groove. The light-shielding layer covers at least a portion of the side surface of the sensing chip and the connection between the metal wire and the bonding pad of the sensing chip. The upper surface of the light-shielding layer is not higher than the upper surface of the photosensitive area. A transparent sealing layer is filled into the groove, and at least covers the upper surface of the light-shielding layer and the upper surface of the photosensitive area.

10. The method for fabricating the photosensor packaging structure according to claim 9, characterized in that: When filling the light-shielding layer, the flow range of the light-shielding layer is limited by the surface tension of the light-shielding layer itself and the inner sidewall of the groove, so that the coverage height h1 of the light-shielding layer covering the side surface of the sensing chip is greater than the coverage height h2 covering one side of the inner sidewall of the groove, and the upper surface of the light-shielding layer forms an arc-shaped concave surface, an arc-shaped convex surface or an inclined surface.

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