Image sensor packaging piece and packaging method thereof
By using a step-structured support frame in the image sensor package to connect to the photosensitive area, combining non-smooth surfaces and low reflectivity film materials, stray light and reliability problems in the prior art are solved, and more efficient production and imaging quality are achieved .
Patent Information
- Application Number
- CN202310684271.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2023-06-09
- Publication Date
- 2024-12-10
AI Technical Summary
The existing image sensor packaging technology has problems such as stray light influence, reliability problems, long production cycles, and high costs. It is especially difficult to achieve good imaging quality and large-scale production in high-pixel large-size products.
The supporting structure is connected to the outer periphery of the photosensitive area of the image sensor chip. The inner wall of the support structure is designed as a step structure to reduce the influence of reflected light, and is cut in the pad part to increase the distance between the photosensitive area and the support structure, combined with non-smooth Surface and low reflectivity film materials to reduce stray light.
Effectively reduces the impact of stray light on image sensors, improves imaging quality, simplifies production processes, reduces costs, and improves the reliability and flexibility of packaging.
Smart Images
Figure CN119108403A_ABST
Abstract
Description
Technical Field
[0001] The present invention relates to the field of semiconductor manufacturing, and in particular to an image sensor package and a packaging method thereof. Background Art
[0002] At present, the mainstream packaging methods of image sensors (CIS: CMOS Image Sensor) include: chip scale package (CSP), chip on board (COB) and flip chip (FC).
[0003] CIS's CSP is a wafer level packaging technology that is currently widely used in low-end and low-pixel (2M pixels or less) image sensors. This packaging technology uses wafer-level glass to bond with the wafer and uses a cofferdam to separate the image sensor chips on the wafer. Then, in the pad area of the polished wafer, a silicon through-hole technology (TSV: Through Silicon Via) is used to make a metal connection on the pad surface or the side of the hole inside the pad surface, or a T-shaped metal contact chip size packaging technology on the side of the pad after cutting. After extending the line on the back of the wafer, a solder ball grid array (BGA: BallGridArray) is made, and then a single sealed cavity image sensor unit is formed after cutting. The module assembly structure is formed by the SMT method at the back end. However, CSP packaging has the following obvious problems: 1. Impact on product performance: The absorption, refraction, reflection and scattering of light by thick supporting glass has a great impact on the performance of image sensors, especially those with small pixel sizes; 2. Reliability issues: The difference in thermal expansion coefficients between components in the packaging structure and the sealed gas in the cavity will cause reliability problems in the subsequent SMT process or changes in the product use environment; 3. Large investment scale, high environmental pollution control requirements, long production cycle, and high unit chip cost, especially for high-pixel and large-size image sensor products.
[0004] CIS's COB packaging is a die-level packaging technology that is currently widely used in high-end, high-pixel products (5M pixels or above) image sensors. This packaging technology uses bonding metal wires to bind the back of the chip after grinding and cutting to the pad of the PCB board, and installs a bracket and lens with an IR glass sheet to form an assembled module structure. However, COB packaging has the following obvious problems: 1. It is very difficult to control dust, requiring an ultra-high clean room level and high manufacturing and maintenance costs; 2. The product design is customized, the cycle is long, and the flexibility is insufficient; 3. It is not easy to mass produce.
[0005] CIS's FC package is a recently emerging die level packaging technology for high-end, high-pixel (5M pixels or above) image sensors. This packaging technology connects the chip pads that have been polished and cut with gold element bumps directly to the pads of the PCB through the action of thermal ultrasound to form a packaging structure. The module assembly structure is formed by the SMT method through the pads or solder balls on the outside of the PCB. However, the FC package has the following obvious problems: 1. The package has very high requirements for the PCB substrate, has a similar thermal expansion coefficient to Si, and is very expensive; 2. The manufacturing reliability is very difficult, and the consistency of the connection between all bumps and pads by thermal ultrasound is very high. The bumps and pads are hard connected and have poor ductility; 3. It is difficult to control dust, the process environment requirements are high, and the cost is very high.
[0006] Figure 1 The present invention is a packaging structure of an image sensor in the prior art. The first end of the metal wire 130 is bonded to the pad 120 of the image sensor chip 100, and the other end of the metal wire 130 is suspended from the image sensor chip 100. A support frame 200 and a light-transmitting cover plate 300 located on the support frame 200 are assembled on the upper part of the photosensitive area 110 of the image sensor chip 100. The support frame 200 is connected to the PCB circuit board. In the prior art, when incident light irradiates the image sensor chip 100, the inner support structure 210 of the support frame 200 will bring stray light due to the close distance between the inner support structure 210 and the photosensitive area 110, thereby affecting the imaging quality of the image. Summary of the invention
[0007] Based on the problems existing in the prior art, the present invention proposes a packaging method for reducing the influence of stray light on image sensors, comprising: providing a mounting frame and an image sensor chip; arranging a supporting structure in the mounting frame; connecting the supporting structure to the periphery of a photosensitive area of the image sensor chip; wherein the inner side wall of the supporting structure is a step structure, which is used to reduce the influence of light reflected from the inner side wall on the photosensitive area.
[0008] The present invention also proposes an image sensor package comprising: a mounting frame and an image sensor chip; a support structure is arranged inside the mounting frame; the support structure is connected to the periphery of the photosensitive area of the image sensor chip; wherein the inner side wall of the support structure is a step structure, which is used to reduce the influence of the light reflected by the inner side wall on the photosensitive area.
[0009] In some embodiments, the step structure includes at least two step structures extending upward or at least two step structures extending downward; and the mounting frame is connected to the circuit board.
[0010] In some embodiments, the step structure includes a multi-step structure extending both upward and downward.
[0011] In some embodiments, at least one layer of film is formed on the inner wall surface of the support structure, which is suitable for reducing the reflectivity of the inner wall to reduce the influence of the light reflected by the inner wall on the photosensitive area.
[0012] In some embodiments, the material of the at least one film includes oxide and fluoride.
[0013] In some embodiments, the inner side wall surface of the support structure is a non-smooth surface, which is suitable for reducing the influence of the light reflected by the inner side wall on the photosensitive area.
[0014] In some embodiments, the step structure includes a first layer structure and a second layer structure; the first layer structure is fixedly connected to the periphery of the photosensitive area of the image sensor chip; the inner side wall of the first layer structure is more than 100um away from the edge of the photosensitive area; the second layer structure is located above the first layer structure and is fixedly connected to the mounting frame; the side wall of the second layer structure is more than 30um away from the side wall of the first layer structure.
[0015] In some embodiments, it also includes: the metal wire; the front side of the image sensor chip includes the photosensitive area and a pad surrounding the photosensitive area; the first end of the metal wire is electrically connected to the pad; and the second end of the metal wire is suspended on the image sensor chip.
[0016] In some embodiments, the pad is partially located in a scribe line region of the image sensor chip; and the first end of the metal wire is electrically connected to the pad located in the scribe line region.
[0017] In some embodiments, the mounting frame is provided with a glass cover plate; at least one of the upper surface or the lower surface of the glass cover plate is coated with a black shading film; a window is opened in the middle of the black shading film, and the distance between the edge of the window and the edge of the incident imaging light is greater than 100um.
[0018] Compared with the prior art, the inner side wall of the support structure of the embodiment of the present invention is a step structure, which can reduce the influence of stray light on the image sensor; further, the pad portion of the image sensor chip is a cutting path, which can further increase the distance from the photosensitive area of the image sensor to the inner side wall of the support structure, and further reduce the influence of stray light on the image sensor. BRIEF DESCRIPTION OF THE DRAWINGS
[0019] Figure 1 It is a schematic diagram of the packaging structure of an image sensor in the prior art.
[0020] Figure 2 FIG. 1 is a schematic structural diagram of an image sensor package according to an embodiment of the present invention.
[0021] Figure 3 FIG. 4 is a schematic structural diagram of an image sensor package according to another embodiment of the present invention.
[0022] Figure 4 FIG. 4 is a schematic structural diagram of an image sensor package according to another embodiment of the present invention.
[0023] Figure 5 FIG. 4 is a schematic diagram of the structure of an image sensor chip according to an embodiment of the present invention. Implementation
[0024] The present invention provides a packaging method for an image sensor, which is used to reduce the influence of stray light on the image sensor, comprising the following steps: providing a mounting frame and an image sensor chip; arranging a supporting structure in the mounting frame; connecting the supporting structure to the periphery of a photosensitive area of the image sensor chip; wherein the inner side wall of the supporting structure is a step structure, which is used to reduce the influence of light reflected by the inner side wall on the photosensitive area.
[0025] The content of the present invention is described below in conjunction with specific embodiments.
[0026] refer to Figures 2 to 4 The image sensor package includes: a mounting frame 20 and an image sensor chip 10; a support structure 21 is arranged inside the mounting frame 20; the support structure 21 is connected to the periphery of the photosensitive area 11 of the image sensor chip 10, and the mounting frame 20 is connected to the PCB circuit board 40; wherein the inner side wall of the support structure 21 is a step structure, which is used to reduce the influence of the light reflected by the inner side wall on the photosensitive area 11.
[0027] The image sensor package also includes: a metal wire 13; the front of the image sensor chip 10 includes a photosensitive area 11 and a pad 12 surrounding the photosensitive area. The first end of the metal wire 13 is electrically connected to the pad 12; the second end of the metal wire 13 is suspended from the image sensor chip 10 and connected to the PCB circuit board 40.
[0028] refer to Figure 5 The pad 12 is partially located in the scribe line 14 area of the image sensor chip 10 ; the first end of the metal wire 13 is electrically connected to the pad 12 partially located in the scribe line 14 area.
[0029] In some embodiments, the step structure of the support structure 21 may include at least two step structures extending upward or at least two step structures extending downward; or, may include multiple step structures extending both upward and downward.
[0030] Specifically, refer to Figure 2 The step structure of the support structure 21 includes a first layer structure 211 and a second layer structure 212. The first layer structure 211 is fixedly connected to the periphery of the photosensitive area 11 of the image sensor chip 10; the distance D1 between the inner side wall of the first layer structure 211 and the edge of the photosensitive area 11 is more than 100 um; the second layer structure 212 is located above the first layer structure 211 and is fixedly connected to the mounting frame 20; the distance D2 between the side wall of the second layer structure 212 and the side wall of the first layer structure 211 is more than 30 um.
[0031] Specifically, refer to Figure 3 The step structure of the support structure 21 includes two step structures 211 and 212 extending downward.
[0032] Specifically, refer to Figure 4 The step structure of the support structure 21 includes multiple step structures 211, 212, and 213 extending upward and downward.
[0033] In some embodiments, at least one film is formed on the inner wall surface of the support structure 21, which is suitable for reducing the reflectivity of the inner wall to reduce the influence of the light reflected by the inner wall on the photosensitive area 11. The material of the at least one film may include oxide, fluoride, etc.
[0034] In some embodiments, the inner wall surface of the support structure 21 is a non-smooth surface, which is suitable for reducing the influence of the light reflected by the inner wall on the photosensitive area.
[0035] In some embodiments, a glass cover plate 30 is disposed on the mounting frame 20; at least one of the upper surface or the lower surface of the glass cover plate 30 is coated with a black shading film 40; a window is opened in the middle of the black shading film 40, and a distance D3 between the edge of the window and the edge of the incident imaging light is greater than 100um.
[0036] Although the present invention is illustrated and described in detail in the drawings and the foregoing description, it should be considered that the illustration and description are illustrative and exemplary rather than restrictive; the present invention is not limited to the above-mentioned embodiments. A person of ordinary skill in the art will be able to understand and implement other changes to the disclosed embodiments by studying the specification, the disclosed content, the drawings and the appended claims. In the actual application of the present invention, a part may perform the functions of multiple technical features cited in the claims. In the claims, the wording "comprising" does not exclude other elements and steps. Any figure marks in the claims should not be construed as limiting the scope.
Claims
1. A packaging method for reducing the influence of stray light on an image sensor, characterized in that: include: Providing a mounting frame and an image sensor chip; a supporting structure is arranged in the mounting frame; connecting the support structure to the periphery of the photosensitive area of the image sensor chip; Wherein, the inner side wall of the support structure is a step structure, which is used to reduce the influence of the light reflected by the inner side wall on the photosensitive area.
2. The method according to claim 1, characterized in that The step structure includes at least two step structures extending upward or at least two step structures extending downward; and the mounting frame is connected to the circuit board.
3. The method according to claim 1, characterized in that The step structure includes a multi-step structure extending upward and downward.
4. The method according to claim 1, characterized in that At least one layer of film is formed on the surface of the inner side wall of the support structure, which is suitable for reducing the reflectivity of the inner side wall to reduce the influence of the light reflected by the inner side wall on the photosensitive area.
5. The method according to claim 1, characterized in that The material of the at least one film includes oxide and fluoride.
6. The method according to claim 1, characterized in that The inner side wall surface of the support structure is a non-smooth surface, which is suitable for reducing the influence of the light reflected by the inner side wall on the photosensitive area.
7. The method according to claim 2, characterized in that The step structure includes a first layer structure and a second layer structure; The first layer structure is fixedly connected to the periphery of the photosensitive area of the image sensor chip; The distance between the inner side wall of the first layer structure and the edge of the photosensitive area is more than 100 um; The second layer structure is located above the first layer structure and is fixedly connected to the installation frame; The distance between the side wall of the second layer structure and the side wall of the first layer structure is greater than 30 um.
8. The method according to claim 7, characterized in that Also includes: The metal wire; The front side of the image sensor chip includes the photosensitive area and a pad surrounding the photosensitive area; The first end of the metal wire is electrically connected to the pad; The second end of the metal wire is suspended on the image sensor chip.
9. The method according to claim 8, characterized in that The pad portion is located in a scribe line area of the image sensor chip; The first end of the metal wire is electrically connected to the portion of the pad located in the scribe line area.
10. The method according to claim 1, characterized in that The mounting frame is provided with a glass cover plate; at least one of the upper surface or the lower surface of the glass cover plate is coated with a black light-shielding film; a window is opened in the middle of the black light-shielding film, and the distance between the edge of the window and the edge of the incident imaging light is more than 100um.
11. An image sensor package, characterized in that: include: An installation frame and an image sensor chip; a support structure is arranged in the installation frame; The support structure is connected to the periphery of the photosensitive area of the image sensor chip; Wherein, the inner side wall of the support structure is a step structure, which is used to reduce the influence of the light reflected by the inner side wall on the photosensitive area; The image sensor package as described in claim 11 is characterized in that the step structure includes at least two step structures extending upward or at least two step structures extending downward; and the mounting frame is connected to the circuit board.
12. The image sensor package according to claim 11, wherein: The step structure includes a multi-step structure extending upward and downward.
13. The image sensor package according to claim 11, wherein: At least one layer of film is formed on the surface of the inner side wall of the support structure, which is suitable for reducing the reflectivity of the inner side wall to reduce the influence of the light reflected by the inner side wall on the photosensitive area.
14. The image sensor package according to claim 11, wherein: The material of the at least one film includes oxide and fluoride.
15. The image sensor package according to claim 11, wherein: The inner side wall surface of the support structure is a non-smooth surface, which is suitable for reducing the influence of the light reflected by the inner side wall on the photosensitive area.
16. The image sensor package according to claim 12, wherein: The step structure includes a first layer structure and a second layer structure; The first layer structure is fixedly connected to the periphery of the photosensitive area of the image sensor chip; The distance between the inner side wall of the first layer structure and the edge of the photosensitive area is more than 200um; The second layer structure is located above the first layer structure and is fixedly connected to the installation frame; The distance between the side wall of the second layer structure and the side wall of the first layer structure is greater than 30 um.
17. The image sensor package according to claim 17, wherein: Also includes: The metal wire; The front side of the image sensor chip includes the photosensitive area and a pad surrounding the photosensitive area; The first end of the metal wire is electrically connected to the pad; The second end of the metal wire is suspended on the image sensor chip.
18. The image sensor package according to claim 18, wherein: The pad portion is located in a scribe line area of the image sensor chip; The first end of the metal wire is electrically connected to the portion of the pad located in the scribe line area.
19. The image sensor package according to claim 1, wherein: The mounting frame is provided with a glass cover plate; at least one of the upper surface or the lower surface of the glass cover plate is coated with a black light-shielding film; a window is opened in the middle of the black light-shielding film, and the distance between the edge of the window and the edge of the incident imaging light is more than 100um.