Photosensitive detector

Abstract

The utility model provides a photosensitive detector, photosensitive detector includes circuit substrate (100), photosensitive detection element (200) and package structure (300), photosensitive detection element (200) sets up on circuit substrate (100), package structure (300) carries out the package to photosensitive detection element (200), package structure (300) includes light transmission package cover board (310) and connecting layer (320), light transmission package cover board (310) is opposite with photosensitive detection element (200) arrangement, the surface of light transmission package cover board (310) towards photosensitive detection element (200) is formed with recess (311), the inner side wall surface roughness of recess (311) is not less than set value, connecting layer (320) surrounds recess (311) setting, and connecting light transmission package cover board (310) with circuit substrate fixed connection.

Description

Technical Field

[0001] This utility model relates to the field of detectors, specifically to a photosensitive detector. Background Technology

[0002] With the development of micro-electromechanical systems (MEMS) technology, the use of photosensitive sensors and photodetectors is becoming increasingly common.

[0003] Typically, a photodetector includes a circuit board, a photosensitive element disposed on the circuit board, and a packaging structure that encapsulates the photosensitive element on the circuit board. The top of the packaging structure is transparent, allowing light to enter the photodetector through the top of the packaging structure and illuminate the photosensitive surface of the photosensitive element.

[0004] Improving the detection accuracy of photodetectors has always been a pursuit in this field. Utility Model Content

[0005] This invention aims to address one of the technical problems in related technologies to a certain extent. To this end, this invention provides a photosensitive detector with relatively high detection accuracy.

[0006] To achieve the above objectives, this utility model provides a photodetector, which includes a circuit board, a photosensitive detection element, and a packaging structure. The photosensitive detection element is disposed on the circuit board, and the packaging structure encapsulates the photosensitive detection element. The packaging structure includes a light-transmitting packaging cover and a connecting layer. The light-transmitting packaging cover is disposed opposite to the photosensitive detection element, and a groove is formed on the surface of the light-transmitting packaging cover facing the photosensitive detection element. The surface roughness of the inner sidewall of the groove is not less than a set value. The connecting layer is disposed around the groove and fixes the light-transmitting packaging cover to the circuit board.

[0007] Optionally, the surface roughness of the inner sidewall of the groove is between Ra0.2 and Ra0.8.

[0008] Optionally, the surface roughness of the inner sidewall of the groove is greater than the surface roughness of the inner top wall of the groove.

[0009] Optionally, the angle between the sidewall of the groove and the circuit board is an acute angle.

[0010] Optionally, the angle between the sidewall of the groove and the circuit board is between 60° and 70°.

[0011] Optionally, the groove has a rectangular cross-section, and the cross-sectional area of ​​the groove gradually decreases from the opening of the groove to the top wall of the groove.

[0012] Optionally, the light-transmitting encapsulation cover has an integral structure; or

[0013] The light-transmitting encapsulation cover includes a glass microlens and a glass pad layer. The glass pad layer is disposed around the glass microlens to form the groove, and the glass pad layer is connected between the glass microlens and the connecting layer.

[0014] Optionally, the photodetector further includes at least one air intake element disposed on the circuit board and located inside the connection layer.

[0015] Optionally, the suction element is offset from the orthographic projection of the top wall of the groove onto the circuit board.

[0016] Optionally, the depth of the groove is between 100 μm and 500 μm.

[0017] In the photodetector provided in this embodiment of the present invention, because the surface roughness of the inner wall of the groove is relatively high, some light signals from the environment or the target are diffusely reflected rather than specularly reflected after being irradiated on the inner wall. This can reduce stray light irradiating the photodetector element to a certain extent (i.e., suppress stray light interference), thereby improving the imaging quality and detection accuracy of the photodetector element. Attached Figure Description

[0018] The present invention will be further described below with reference to the accompanying drawings:

[0019] Figure 1 This is a schematic diagram of one embodiment of the photosensitive detector provided in this utility model.

[0020] Figure 2 This is a schematic diagram of the sandblasting process;

[0021] Figure 3 This is a schematic diagram illustrating the groove structure. Detailed Implementation

[0022] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described are intended to explain this utility model and should not be construed as limiting it.

[0023] The terms "an embodiment," "example," or "trademark" used in this specification refer to a particular feature, structure, or characteristic described in connection with the embodiment itself that may be included in at least one embodiment disclosed in this utility model. The phrase "in an embodiment" appearing in various places throughout the specification does not necessarily refer to the same embodiment.

[0024] After the photosensitive detection element and other supporting electronic components in a photodetector are mounted on the circuit board, they all need to protrude a certain height from the circuit board. This requires leaving sufficient space for the photosensitive detection element when using a transparent encapsulation cover. Because the thickness of the encapsulation solder cannot be too thick, in order to leave enough space for the photosensitive detection element during encapsulation, a groove opposite to the photosensitive detection element is usually formed on the transparent encapsulation cover. In related technologies, when processing the transparent encapsulation cover of the photodetector, due to limitations in process precision and processing cost, it is difficult to make the inner sidewall of the groove formed on the transparent cover vertical. That is to say, there is always an angle between the inner sidewall and the inner top wall of the groove. Furthermore, in related technologies, dry etching or wet etching methods are often used to form the grooves on the packaging cover. In this case, the inner surface of the groove is often mirrored. As mentioned above, there is an angle between the inner sidewall and the inner top wall of the groove. This causes light to be reflected at the inner sidewall of the groove and then shine on the photosensitive element of the photodetector again, causing light pollution to the photosensitive element and reducing the detection accuracy of the photosensitive element.

[0025] In view of this, the present invention provides a photosensitive detector, such as... Figure 1 As shown, the photodetector includes a circuit board 100, a photosensitive detection element 200, and a packaging structure 300. The photosensitive detection element 200 is disposed on the circuit board 100, and the packaging structure 300 encapsulates the photosensitive detection element 200. The packaging structure 300 includes a light-transmitting packaging cover plate 310 and a connecting layer 320. The light-transmitting packaging cover plate 310 is disposed opposite to the photosensitive detection element 200. A groove 311 is formed on the surface of the light-transmitting packaging cover plate 310 facing the photosensitive detection element 200. The surface roughness of the inner sidewall of the groove is not less than a set value. The connecting layer 320 is disposed around the groove 311 and fixes the light-transmitting packaging cover plate 310 to the circuit board 100.

[0026] Because the surface roughness of the inner wall of the groove 311 is relatively high, some light signals from the environment or the target will undergo diffuse reflection rather than specular reflection after being irradiated on the inner wall. This can reduce stray light irradiating the photosensitive detection element to a certain extent (i.e., suppress stray light interference) and improve the imaging quality and detection accuracy of the photosensitive detection element.

[0027] In this embodiment of the invention, the value of the set point is not specifically limited, as long as it can form diffuse reflection on the inner surface of the sidewall of the groove 311 and suppress stray light. Optionally, the set point can be between Ra0.2 and Ra0.8.

[0028] To ensure that sufficient target light (or detection light) can pass through the light-transmitting encapsulation cover 310 and illuminate the photosensitive detection element 200, optionally, the surface roughness of the inner sidewall of the groove 311 is greater than the surface roughness of the inner top wall of the groove 311.

[0029] To reduce manufacturing costs, optionally, the angle θ between the sidewall of the groove 311 and the circuit board substrate is an acute angle.

[0030] To improve the overall strength of the light-transmitting encapsulation cover 310, as an optional implementation, the angle θ between the sidewall of the groove 311 and the circuit board 100 is greater than 60°, thereby ensuring that the photodetector has a certain thickness and overall strength.

[0031] Alternatively, the angle θ between the sidewall of the groove 311 and the circuit board 100 is between 60° and 70°.

[0032] In this embodiment of the invention, the specific shape of the groove 311 is not particularly limited, as long as the angle between its sidewall and the circuit board 100 is an acute angle. For ease of manufacturing, the cross-section of the groove 311 is rectangular, and the cross-sectional area of ​​the groove 311 gradually decreases from the opening of the groove 311 to the top wall of the groove 311.

[0033] In this embodiment of the invention, no particular limitation is made on how the light-transmitting encapsulation cover 310 with the groove 311 is obtained. As an optional implementation, a single-layer glass mother plate can be processed to form the groove 311, that is, the light-transmitting encapsulation cover 310 has an integral and single-layer structure. For example, the groove 311 can be formed on the glass mother plate by sandblasting. The sandblasting process will be described in detail below, and will not be repeated here.

[0034] As an alternative implementation, the light-transmitting encapsulation cover 310 may further include a glass microlens and a glass pad layer, the glass pad layer surrounding the glass microlens to form a groove 311, and the glass pad layer connecting the glass microlens and the connecting layer 320. In this implementation, the glass microlens and the glass pad layer can be fixedly connected by a glass thermocouple.

[0035] In this embodiment of the invention, the specific material of the connecting layer 320 is not specifically limited, as long as it can fix the light-transmitting encapsulation cover 310 to the circuit board 100. As an optional implementation, the connecting layer 320 is a low-temperature soldering layer.

[0036] As an optional implementation, the photodetector further includes at least one suction element 400 disposed on the circuit board 100 and located inside the connection layer 320.

[0037] By setting the gas-absorbing element 400, residual gas molecules (such as water vapor, oxygen, nitrogen, etc.) inside the photodetector, as well as trace amounts of gas released by the material, can be adsorbed to maintain a high vacuum environment.

[0038] Optionally, the orthographic projections of the suction element 400 and the top wall of the groove 311 on the circuit board 100 are offset, thereby reducing the impact on reflected light.

[0039] In this embodiment of the invention, the depth of the groove 311 is not specifically limited. The depth of the groove 311 can be determined based on the thickness of the light-transmitting encapsulation cover 310 and the height of the photosensitive detection element 200 protruding from the circuit board 100, as long as sufficient installation space is provided for the photosensitive detection element 200. As an optional implementation, the depth of the groove 311 is between 100μm and 500μm.

[0040] As mentioned above, grooves 311 can be formed on a single-layer glass motherboard by sandblasting. The following will combine... Figure 2 and Figure 3 This paper describes how to manufacture the photosensitive detector provided in the embodiments of this utility model.

[0041] Specifically, processing a single-layer glass motherboard may include:

[0042] A mask layer 10 is formed on the glass mother plate 31, and a plurality of through holes are formed on the mask layer 10;

[0043] A glass mother plate 31 with a mask layer 10 is placed on the worktable 21 of the sandblasting device and located below the sandblasting nozzle of the spray gun 41. A baffle 51 is set between the sandblasting nozzle and the glass mother plate 31 to control the sandblasting range of the sandblasting nozzle.

[0044] The spray gun 41 is controlled to perform sandblasting. During the sandblasting process, the side wall angle of the groove formed by sandblasting is detected in real time until the groove position with the side wall tilt angle and depth both meet the requirements is obtained.

[0045] It should be noted that, in this embodiment of the invention, the sandblasting angle α of the spray gun can be determined by the following formula:

[0046]

[0047] Where θ is the angle between the sidewall of the groove and the surface of the glass mother plate;

[0048] BC is the depth of the groove;

[0049] d is the distance between the blasting nozzle and the surface of the mask layer;

[0050] Δ is a correction value used to adjust the size of angle α, thereby controlling the verticality of the sandblasting jet.

[0051] α is the spray angle of the spray gun.

[0052] In this embodiment of the invention, by adjusting the values ​​of α, d, and Δ, θ can be made to be between 60° and 70°.

[0053] In this embodiment of the invention, the roughness of the inner surface of the groove is controlled by selecting the diameter of the sand grains and the sandblasting time. Specifically, the roughness of the groove surface is related to the diameter of the sand grains and the sandblasting time as shown in the following formula (2).

[0054]

[0055] Where Ra is the surface roughness of the inner wall of the groove;

[0056] k and γ are empirical constants related to the properties of glass materials and sandblasting processes;

[0057] P is the sandblasting pressure;

[0058] t is the sandblasting time;

[0059] d p The diameter of the sand grain is denoted as .

[0060] Typically, the sandblasting pressure P is between 0.2 MPa and 0.5 MPa.

[0061] To better control the sandblasting process, laser angle sensors, scanning electron microscopes, and roughness measuring instruments can be used to detect various parameters of the formed groove.

[0062] After obtaining grooves with the required sidewall tilt angle and depth, the sandblasting process ends, the mask layer is peeled off, and the subsequent bonding process is carried out. The bonding process includes:

[0063] The surface of the circuit board is treated with oxygen plasma or chemical activation.

[0064] Solder is applied to the circuit board. For example, transient liquid phase bonding or eutectic bonding can be used. The soldering materials are mostly low-melting-point metals (Sn, In) and high-melting-point metals (Cu, Au).

[0065] Align the light-transmitting encapsulation cover with the circuit board;

[0066] Low-temperature bonding is performed, with bonding temperatures between 100°C and 300°C, to ensure that thermal stress during the encapsulation process is minimized.

[0067] After packaging, the resulting photodetector needs to undergo performance testing, specifically including:

[0068] Environmental stability testing: The packaged samples are subjected to environmental tests such as high temperature, damp heat, and thermal cycling to evaluate the long-term stability and sealing of the photodetector.

[0069] Optical performance testing: The reflectance and transmittance of the packaged sample were detected using an infrared spectrometer to verify the improvement of the reflection effect by the sandblasting process.

[0070] Mechanical performance testing: Shear and tensile mechanical tests are performed on the packaged samples to ensure that the mechanical strength of the packaged parts meets the requirements in actual applications.

[0071] After testing, it was found that the photodetector provided in this embodiment of the invention can effectively reduce the impact of sidewall stray light on detection performance, and has better airtightness, thermal stability and optical performance.

[0072] The above are merely specific embodiments of this utility model, but the scope of protection of this utility model is not limited thereto. Those skilled in the art should understand that this utility model includes, but is not limited to, the contents described in the accompanying drawings and the specific embodiments above. Any modifications that do not depart from the functional and structural principles of this utility model will be included within the scope of the claims.

Claims

1. A photodetector, the photodetector comprising a circuit board (100), a photosensitive element (200), and a packaging structure (300), wherein the photosensitive element (200) is disposed on the circuit board (100), and the packaging structure (300) encapsulates the photosensitive element (200), characterized in that, The encapsulation structure (300) includes a light-transmitting encapsulation cover plate (310) and a connecting layer (320). The light-transmitting encapsulation cover plate (310) is disposed opposite to the photosensitive detection element (200). A groove (311) is formed on the surface of the light-transmitting encapsulation cover plate (310) facing the photosensitive detection element (200). The surface roughness of the inner sidewall of the groove (311) is not less than a set value. The connecting layer (320) is disposed around the groove (311) and fixes the light-transmitting encapsulation cover plate (310) to the circuit board.

2. The photodetector according to claim 1, characterized in that, The surface roughness of the inner wall of the groove (311) is between Ra0.2 and Ra0.

8.

3. The photodetector according to claim 1, characterized in that, The surface roughness of the inner sidewall of the groove (311) is greater than the surface roughness of the inner top wall of the groove.

4. The photodetector according to claim 1, characterized in that, The angle (θ) between the sidewall of the groove (311) and the circuit board (100) is an acute angle.

5. The photodetector according to claim 4, characterized in that, The angle (θ) between the sidewall of the groove (311) and the circuit board (100) is between 60° and 70°.

6. The photodetector according to claim 4, characterized in that, The groove (311) has a rectangular cross-section, and the cross-sectional area of ​​the groove (311) gradually decreases from the opening of the groove (311) to the top wall of the groove (311).

7. The photodetector according to any one of claims 1 to 6, characterized in that, The light-transmitting encapsulation cover (310) has an integral structure; or The light-transmitting encapsulation cover (310) includes a glass microlens (312) and a glass pad layer (313). The glass pad layer (313) is disposed around the glass microlens (312) to form the groove (311). The glass pad layer (313) is connected between the glass microlens (312) and the connecting layer (320).

8. The photodetector according to any one of claims 1 to 6, characterized in that, The photodetector also includes at least one air intake element (400), which is disposed on the circuit board (100) and located inside the connection layer (320).

9. The photodetector according to claim 8, characterized in that, The suction element (400) and the top wall of the groove (311) are offset from each other on the circuit board (100).

10. The photodetector according to any one of claims 1 to 6, characterized in that, The depth of the groove (311) is between 100 μm and 500 μm.

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