Angled glass edge for image sensor packaging

Abstract

The present disclosure relates to angled glass edges for image sensor packages. For example, a digital image sensor package includes an image sensor substrate and a glass cover. The image sensor substrate carries a photodiode. The glass cover has a bottom surface, a top surface opposite the bottom surface, and sidewalls defining a peripheral edge of the glass cover. The glass cover overlies the photodiode. The surface area of ​​the top surface of the glass cover is greater than the surface area of ​​the bottom surface of the glass cover, such that the sidewalls are not perpendicular to the top and bottom surfaces of the glass.

Description

[0001] Related applications

[0002] This application claims priority to U.S. Provisional Patent Application No. 63 / 034,464, filed on June 4, 2020, which is incorporated herein by reference to the maximum extent permitted by law. Technical Field

[0003] The present disclosure relates to the field of digital image sensors, and more particularly to a design of a glass cover for an image sensor of an image sensor package, which reduces the incidence of stray light on the image sensor, thereby reducing noise in an image acquired by the image sensor. Background Art

[0004] Digital image sensors are widely used in various electronic devices (such as laptops, smartphones, and tablets) to provide image capture capabilities.

[0005] Figure 1 A known digital image sensor package 10 in a die-on-glass packaging arrangement is shown. An image sensor substrate 12 is disposed on a printed circuit board 11, and a photodiode 13 is formed in or on image sensor substrate 12. A transparent adhesive layer 14 physically couples a glass cover 15 above image sensor substrate 12. While this design is relatively simple and widely produced, a problem exists: some incident light IL may follow a path that enters the top side of glass 15 and then reflects from the sidewalls of glass 15 on a path that causes it to strike photodiode 13. This path causes this incident light IL to carry no usable information about the captured scene, and instead simply causes noise in the information about the scene captured by photodiode 13.

[0006] Attempts have been made to alleviate or eliminate this problem. Figure 2 As shown in the digital image sensor package 10' of FIG. 1 , light absorbing material 17 may be placed at the edge of glass 15 so that incident light IL that would otherwise reflect from the sidewalls of glass 15 is absorbed, minimizing noise in the information about the scene captured by photodiode 13. While this design is feasible, it adds additional steps to the manufacture of image sensor package 10', may be incompatible with the physical layout of some digital image sensor packages, and may be unreliable because light absorbing material 17 may become detached.

[0007] Therefore, further development is needed. Summary of the Invention

[0008] Disclosed herein is a digital image sensor package, comprising: an image sensor substrate carrying a photodiode; and a glass cover having a bottom surface, a top surface opposite the bottom surface, and sidewalls defining a peripheral edge of the glass cover, wherein the glass cover covers over the photodiode; wherein the surface area of ​​the top surface of the glass cover is greater than the surface area of ​​the bottom surface of the glass cover, such that the sidewalls are not perpendicular to the top and bottom surfaces of the glass.

[0009] The sidewall and the top surface of the glass cover may form an acute angle, and the sidewall and the bottom surface of the glass cover may form an obtuse angle.

[0010] The outer surface of the side wall may be flat.

[0011] The space between the sidewalls and the image sensor substrate may not contain light absorbing material.

[0012] At least a portion of the bottom surface of the glass cover can be physically coupled to the image sensor substrate.

[0013] The printed circuit board may carry the image sensor substrate.

[0014] Mounting hardware may physically couple a portion of the bottom surface of the glass cover to the printed circuit board.

[0015] The mounting hardware may include a first portion physically coupled to and extending upward from the printed circuit board, a second portion extending inward from a periphery of the image sensor substrate toward the photodiode, and an intermediate connecting portion connecting the first portion to the second portion. A portion of the bottom surface of the glass cover may be physically coupled to the second portion of the mounting hardware.

[0016] Also disclosed herein is a digital image sensor package comprising: a printed circuit board; an image sensor substrate stacked on the printed circuit board; and a transparent cover associated with the image sensor substrate and having a bottom surface, a top surface opposite the bottom surface, and sidewalls defining a peripheral edge of the transparent cover, wherein the transparent cover overlies the image sensor substrate. The sidewalls and the top surface of the transparent cover form a first angle, and the sidewalls and the bottom surface of the transparent cover form a second angle different from the first angle. The first and second angles cause light entering the transparent cover on a trajectory that would cause the light to strike the sidewall to be reflected to a new trajectory that avoids the image sensor substrate.

[0017] The first angle may be an acute angle, and the second angle may be an obtuse angle.

[0018] At least a portion of the bottom surface of the transparent cover may be physically coupled to the image sensor substrate.

[0019] Mounting hardware may physically couple a portion of the bottom surface of the transparent cover to the printed circuit board.

[0020] The mounting hardware may include a first portion physically coupled to and extending upward from the printed circuit board, a second portion extending inward from a periphery of the image sensor substrate, and an intermediate connecting portion connecting the first portion to the second portion. A portion of the bottom surface of the transparent cover may be physically coupled to the second portion of the mounting hardware.

[0021] The outer surface of the side wall may be flat.

[0022] The space between the sidewalls and the image sensor substrate may not contain light absorbing material.

[0023] This document also discloses a digital image sensor package, including an image sensor and a glass cover covering the image sensor. The glass cover has a trapezoidal cross-section, wherein the top surface of the glass cover has a larger surface area than the bottom surface of the glass cover, the bottom surface faces the image sensor, and the top surface faces away from the image sensor.

[0024] The surface area of ​​the top surface of the glass cover is greater than the surface area of ​​the bottom surface of the glass cover, which may result in a portion of free space being located between the top surface and the image sensor.

[0025] At least a portion of the bottom surface of the glass cover may be physically coupled to the image sensor.

[0026] A printed circuit board may carry an image sensor, and mounting hardware may physically couple a portion of the bottom surface of the cover glass to the printed circuit board. The mounting hardware may include a first portion physically coupled to and extending upward from the printed circuit board, a second portion extending inward from a periphery of the image sensor, and an intermediate connecting portion connecting the first portion to the second portion. A portion of the bottom surface of the cover glass may be physically coupled to the second portion of the mounting hardware.

[0027] The trapezoidal cross-section of the glass cover may include a top surface, a bottom surface, and sidewalls connecting the top surface to the bottom surface. The trapezoidal cross-section of the glass cover may cause light entering the transparent cover on a trajectory that causes the light to hit the sidewalls to be reflected away from the image sensor.

[0028] A method aspect is also disclosed herein. The method is a method for reducing noise captured by an image sensor. The method may include attaching a bottom surface of a glass cover to the image sensor; allowing light to be incident on the glass cover; and shaping the glass cover so that when the light incident on the glass cover strikes a sidewall of the glass cover, the sidewall reflects the light in a trajectory away from the image sensor.

[0029] Shaping the glass cover may include shaping the glass cover to have a trapezoidal cross-section, so that when light incident to the glass cover is incident on a sidewall of the trapezoidal cross-section, the sidewall reflects the light in a trajectory away from the image sensor. BRIEF DESCRIPTION OF THE DRAWINGS

[0030] Figure 1 is a side view of a known digital image sensor package.

[0031] Figure 2 Light absorbing materials are used to alleviate Figure 1 A side view of a known digital image sensor package illustrating disadvantages of the known digital image sensor package.

[0032] Figure 3 is a side view of a glass-on-die digital image sensor package disclosed herein, which solves the problem of Figure 1 Disadvantages of known digital image sensor packages.

[0033] Figure 4 is a side view of a digital image sensor package in the form of a grid array disclosed herein, which is solved by appropriately shaping the glass Figure 1 Disadvantages of known digital image sensor packages. DETAILED DESCRIPTION

[0034] The following disclosure enables those skilled in the art to make and use the subject matter disclosed herein. The general principles described herein may be applied to embodiments and applications other than those described in detail above without departing from the spirit and scope of the present disclosure. The present disclosure is not limited to the embodiments shown, but is to be accorded the widest scope consistent with the principles and features disclosed or suggested herein.

[0035] Figure 3 , a digital image sensor package 30 in a glass-on-die packaging arrangement is shown. An image sensor substrate 32 is arranged on a printed circuit board (PCB) 31, and a photodiode 33 is formed in or on the image sensor substrate 32. Over the image sensor substrate 32, a transparent adhesive layer 34 is physically coupled to a cover 35 (e.g., glass, such as a glass lens).

[0036] In more detail, the glass cover 35 has a top surface 35a, a bottom surface 35b, and sidewalls 35c that define the peripheral edge of the glass cover. The bottom surface 35b of the glass cover 35 is physically coupled to the image sensor substrate 32 above the photodiode 33 via a transparent adhesive layer 34. The diameter and / or surface area of ​​the top surface 35a of the glass cover 35 is larger than the diameter and / or surface area of ​​the bottom surface 35b, such that the sidewalls 35c are angled relative to the normal (i.e., angled relative to a direction perpendicular to the bottom surface 35b and / or a plane forming the photodiode 33 with respect to the bottom of the substrate 32 and / or PCB 31). In particular, the angle formed by the sidewalls 35c and the bottom surface 35b is an obtuse angle (greater than 90°), and / or the angle formed by the sidewalls 35c and the top surface 35a is an acute angle (less than 90°).

[0037] As shown in the figure, the angle formed by the side wall 35 c relative to the top surface 35 a and / or the bottom surface 35 b of the glass cover 35 is intended to cause the incident light IL reflected from the side wall 35 c to be reflected along a trajectory that avoids the photodiode 33. In this way, although the incident light IL is reflected from the side wall 35 c, it does not generate noise in the information about the scene captured by the photodiode 33, thereby providing better image quality.

[0038] Additionally, another benefit provided by the shape of the sidewalls 35c of the glass cover 35 is that no light absorbing material (such as in Figure 2 In practice, digital image sensor package 30 has no light absorbing material between sidewall 35 c and the top of image sensor substrate 32, and no such light absorbing material exists between sidewall 35 c and the top of image sensor substrate 32 (such as in FIG. Figure 2 By eliminating such light absorbing material, steps for forming such material and attaching it to the glass cover 35 during manufacturing are eliminated.

[0039] Figure 4 Another digital image sensor package 30' is shown in FIG. The digital image sensor package 30' is arranged in a grid array. Figure 3Like the digital image sensor package 30 of FIG. 1 , an image sensor substrate 32 is provided on a printed circuit board 31, and a photodiode 33 is formed in or on the image sensor substrate 32. However, here, mounting hardware 36 is attached to the printed circuit board 31 and surrounds at least a portion of the periphery of the image sensor substrate 32 in a spaced-apart manner so as not to contact the image sensor substrate 32. The mounting hardware 36 includes a first portion 36 a attached to and extending upward from the printed circuit board 31, a second portion 36 c extending inward from the periphery of the image sensor substrate 32 toward the photodiode 33, and an intermediate connecting portion 36 b connecting the first portion 36 a to the second portion 36 c.

[0040] An adhesive layer 34 (which may be transparent) physically couples a glass cover 35 (e.g., a lens) to the top surface of the second portion 36 c of the mounting hardware 36, such that the glass cover 35 overlies the image sensor substrate 32. The glass cover 35 has a top surface 35 a, a bottom surface 35 b, and sidewalls 35 c. The periphery of the bottom surface 35 b of the glass cover 35 is physically coupled to the second portion 36 c of the mounting hardware 36. The diameter and / or surface area of ​​the top surface 35 a of the glass cover 35 is greater than the diameter and / or surface area of ​​the bottom surface 35 b, such that the sidewalls 35 c are angled relative to the normal (as described above). As previously described, the angle formed by the side wall 35 c and the bottom surface 35 b is an obtuse angle (greater than 90°), and / or the angle formed by the side wall 35 c and the top surface 35 a is an acute angle (less than 90°), and the purpose of the angle formed by the side wall 35 c relative to the top surface 35 a and the bottom surface 35 b of the glass cover 35 is to cause the incident light IL reflected from the side wall 35 c to be reflected along a trajectory that avoids the photodiode 33.

[0041] Figure 3-Figure 4 The glass cover 35 can be formed to have the above-mentioned angles by an appropriate cutting method (e.g., using mechanical sawing or chemical etching). For example, the angle formed by the sidewall 35c relative to the top surface 35a can be in the range of 40° to 60°, and the angle formed by the sidewall 35c relative to the bottom surface 35b can be in the range of 120° to 140°. Other suitable angles can also be used. The top surface 35a and the bottom surface 35b are shown as straight rather than curved, although in some applications, the top surface 35a and the bottom surface 35b can be concave or convex as desired. In addition, in some examples, the sidewall 35c can be concave or convex as desired.

[0042] Although some of the incident light IL may still make its way to the photodiode 33 and reflect from the sidewall 35c, Figure 1-Figure 2 Compared with the design using Figure 3-Figure 4 The design reduces this.

[0043] It should be noted that although the cover 35 is described as being constructed of glass, it may be constructed of other materials, such as acrylic. Figure 3-Figure 4 In FIG. 3 , cover 35 may be a lens, but may not be a lens and may simply serve as a cover for image sensor substrate 32 .

[0044] While the present invention has been described with respect to a limited number of embodiments, those skilled in the art will appreciate that, having benefit of this disclosure, other embodiments can be devised which do not depart from the scope of the present disclosure. Accordingly, the scope of the present disclosure is limited only by the claims appended hereto.

Claims

1. A digital image sensor package, comprising: an image sensor substrate, carrying a photodiode; as well as a glass cover having a bottom surface, a top surface opposite the bottom surface, and sidewalls defining a peripheral edge of the glass cover, wherein the glass cover is monolithic and covers over all of the photodiodes; wherein the surface area of ​​the top surface of the glass cover is greater than the surface area of ​​the bottom surface of the glass cover such that the sidewalls are non-perpendicular to one or both of the top and bottom surfaces of the glass; and wherein the surface area of ​​the top surface of the image sensor substrate is greater than the surface area of ​​the bottom surface of the glass cover, wherein the sidewall and the top surface of the glass cover form an acute angle, and wherein the sidewall and the bottom surface of the glass cover form an obtuse angle. 2 . The digital image sensor package of claim 1 , wherein an outer surface of the sidewall is flat. 3 . The digital image sensor package of claim 1 , wherein the space between the sidewalls and the image sensor substrate does not contain a light absorbing material. 4 . The digital image sensor package of claim 1 , wherein at least a portion of the bottom surface of the glass cover is physically coupled to the image sensor substrate. 5 . The digital image sensor package according to claim 1 , further comprising a printed circuit board carrying the image sensor substrate. 6 . The digital image sensor package of claim 5 , further comprising mounting hardware that physically couples a portion of the bottom surface of the glass cover to the printed circuit board.

7. The digital image sensor package of claim 6 , wherein the mounting hardware comprises a first portion physically coupled to and extending upward from the printed circuit board, a second portion extending inward from a periphery of the image sensor substrate toward the photodiode, and an intermediate connecting portion connecting the first portion to the second portion, wherein a portion of the bottom surface of the glass cover is physically coupled to the second portion of the mounting hardware.

8. A digital image sensor package, comprising: printed circuit boards; an image sensor substrate stacked on the printed circuit board and including a photodiode; as well as a transparent cover associated with the image sensor substrate and having a bottom surface, a top surface opposite the bottom surface, and sidewalls defining a peripheral edge of the transparent cover, wherein the transparent cover is monolithic and covers over all of the photodiodes of the image sensor substrate, wherein the top surface of the image sensor substrate has a surface area greater than a surface area of ​​the bottom surface of the transparent cover; wherein the sidewall and the top surface of the transparent cover form a first angle, and the sidewall and the bottom surface of the transparent cover form a second angle different from the first angle, and wherein the first angle and the second angle are such that light entering the transparent cover in a first trajectory is reflected in a second trajectory, the first trajectory causing the light to strike the sidewall, and the second trajectory avoiding the image sensor substrate, The first angle is an acute angle, and the second angle is an obtuse angle. 9 . The digital image sensor package of claim 8 , wherein at least a portion of the bottom surface of the transparent cover is physically coupled to the image sensor substrate.

10. The digital image sensor package of claim 8, further comprising mounting hardware that physically couples a portion of the bottom surface of the transparent cover to the printed circuit board.

11. The digital image sensor package of claim 10 , wherein the mounting hardware comprises a first portion physically coupled to and extending upward from the printed circuit board, a second portion extending inward from a periphery of the image sensor substrate, and an intermediate connecting portion connecting the first portion to the second portion, wherein a portion of the bottom surface of the transparent cover is physically coupled to the second portion of the mounting hardware. 12 . The digital image sensor package of claim 8 , wherein an outer surface of the sidewall is flat. 13 . The digital image sensor package of claim 8 , wherein a space between the sidewalls and the image sensor substrate does not contain a light absorbing material.

14. A digital image sensor package, comprising: image sensors, including photodiodes; as well as a glass cover covering all the photodiodes of the image sensor and having a trapezoidal cross-section, wherein a top surface of the glass cover has a larger surface area than a bottom surface of the glass cover, the bottom surface faces the image sensor, and the top surface faces away from the image sensor; wherein the glass cover is monolithic and a top surface of the image sensor has a surface area greater than a surface area of ​​a bottom surface of the glass cover, wherein the sidewall of the glass cover and the top surface form an acute angle, and wherein the sidewall of the glass cover and the bottom surface form an obtuse angle. 15 . The digital image sensor package of claim 14 , wherein the surface area of ​​the top surface of the glass cover is greater than the surface area of ​​the bottom surface of the glass cover such that a portion of free space is located between the top surface and the image sensor. 16 . The digital image sensor package of claim 14 , wherein at least a portion of the bottom surface of the glass cover is physically coupled to the image sensor.

17. The digital image sensor package according to claim 14, further comprising: a printed circuit board carrying the image sensor; as well as mounting hardware to physically couple a portion of the bottom surface of the glass cover to the printed circuit board; The mounting hardware includes a first portion physically coupled to the printed circuit board and extending upward from the printed circuit board, a second portion extending inward from a periphery of the image sensor, and an intermediate connecting portion connecting the first portion to the second portion, wherein a portion of the bottom surface of the glass cover is physically coupled to the second portion of the mounting hardware.

18. The digital image sensor package of claim 14 , wherein the trapezoidal cross-section of the glass cover comprises the top surface, the bottom surface, and sidewalls connecting the top surface to the bottom surface; and wherein the trapezoidal cross-section of the glass cover causes light entering the transparent cover on a trajectory that causes the light to strike the sidewalls to be reflected away from the image sensor.

19. A method of reducing noise captured by an image sensor, the method comprising: attaching a bottom surface of a glass cover to the image sensor; allowing light to impinge upon said glass covering; shaping the glass cover so that when light impinging on the glass cover strikes a sidewall of the glass cover, the sidewall reflects the light in a trajectory away from the image sensor, wherein the sidewall and the top surface of the glass cover form an acute angle, and wherein the sidewall and the bottom surface of the glass cover form an obtuse angle.

20. The method of claim 19, wherein shaping the glass cover comprises: The glass cover is shaped to be trapezoidal in cross-section so that when light striking the glass cover strikes a sidewall of the trapezoidal cross-section, the sidewall reflects the light in a trajectory away from the image sensor.

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