Photoelectric detector TO packaging structure

Abstract

The utility model discloses a TO packaging structure of a photoelectric detector. The packaging structure comprises a metal shell, a light window arranged at the top of the shell, a tube socket fixed at the bottom of the shell, and a detector chip arranged on the tube socket. The micro-lens array is integrated on the inner surface of the light window, and the focus of the micro-lens array coincides with the light-sensitive surface of the detector chip. The micro-lens array is composed of hexagonal convex lens units which are closely arranged and covers a light-transmitting area of the light window, and efficient convergence of incident light is achieved. The light window is of a double-layer structure and comprises an outer plane glass layer and a hot-melting integrated micro-lens array layer, and the risk of failure of a gluing interface is avoided. The light window is hermetically connected with the metal shell through the annular welding part, and the micro-lens array is located on the inner side of the annular welding part to ensure the stability of an optical path. A signal pin on the tube socket is connected with a chip electrode through a gold wire, and a gold wire bridging path is located below the focus of the micro lens, so that incident light is prevented from being shielded.

Description

TECHNICAL FIELD

[0001] The utility model relates to the field of optoelectronic device packaging technology, and specifically relates to a photoelectric detector TO packaging structure. BACKGROUND

[0002] The photoelectric detector TO packaging structure is a widely used device packaging form, and its typical structure comprises a metal shell, a top light-transmitting window, a bottom tube seat and an embedded detector chip. In the prior art, the light window is usually made of flat glass or sapphire material and is directly sealed on the top of the metal shell to allow light transmission. However, such a flat light window lacks optical focusing function, and the incident light cannot be efficiently converged to the photosensitive area of the detector chip due to the interface refraction and scattering effect in the transmission process. Especially when the photosensitive area of the detector chip is extremely small, a large amount of incident light cannot be effectively utilized due to scattering loss, resulting in a significant reduction in photoelectric conversion efficiency.

[0003] To solve the problem of light coupling efficiency of the flat light window, some technical solutions attempt to add a separate condensing lens outside the light window. Such a lens is usually fixed on the surface of the light window by a gluing process and focuses the incident light by using the curvature of the lens. However, the gluing interface is prone to aging, cracking and other problems under long-term high temperature, high humidity or temperature cycling conditions, which causes the lens to deviate or even fall off, seriously affecting the packaging reliability and service life. Whether it is a flat light window or an external lens solution, the core contradiction lies in the difficulty of balancing optical performance and reliability: the flat light window has a simple process but low light efficiency; the external lens can improve the light efficiency, but introduces new failure risks due to the gluing interface.

[0004] Therefore, there is a need for a photoelectric detector TO packaging structure to solve the above technical problems. SUMMARY

[0005] The utility model aims at making up for the deficiency of prior art and provides a photoelectric detector TO packaging structure.

[0006] To achieve the above-mentioned purpose, the utility model provides the following technical scheme: a photoelectric detector TO packaging structure, comprising a metal shell, a light window arranged on the top of the metal shell, a tube seat fixed on the bottom of the metal shell, a detector chip arranged on the tube seat, a microlens array arranged on the inner surface of the light window, and the focal point of the microlens array coincides with the photosensitive surface of the detector chip.

[0007] Preferably, the photoelectric detector TO packaging structure, wherein the microlens array is composed of a plurality of convex lens units, each convex lens unit is arranged in a hexagonal shape, and covers the entire light-transmitting area of the light window.

[0008] Preferably, the photoelectric detector TO packaging structure, wherein the light window is a double-layer structure, comprising an outer layer of planar glass layer and a microlens array layer, and the microlens array layer is integrally connected with the outer layer of planar glass layer by hot melting.

[0009] Preferably, the photoelectric detector TO packaging structure, wherein the radius of curvature of the microlens array is 0.1-0.5mm, and the central axis of each lens unit is perpendicular to the light-sensitive surface of the detector chip.

[0010] Preferably, the photoelectric detector TO packaging structure, wherein the light window and the metal shell are sealingly connected through an annular welding portion, and the microlens array is located in the inner side region of the annular welding portion.

[0011] Preferably, the photoelectric detector TO packaging structure, wherein the tube seat is further provided with a signal pin and a ground pin, the signal pin is connected with the electrode of the detector chip through a gold wire, and the jumper path of the gold wire is located below the focal point of the microlens array.

[0012] The photoelectric detector TO packaging structure has the following beneficial effects:

[0013] Firstly, the photoelectric detector TO packaging structure integrates the microlens array on the inner surface of the light window, so that the incident light is accurately converged to the light-sensitive surface of the detector chip after being focused by the lens unit, the light scattering loss is effectively reduced, and the photoelectric conversion efficiency is improved.

[0014] Secondly, the photoelectric detector TO packaging structure covers the light transmission area of the light window by the closely arranged hexagonal microlens array, eliminates the edge light leakage problem, and optimizes the layout of the gold wire jumper path to avoid the shielding of the bonding wire to the focused light. BRIEF DESCRIPTION OF DRAWINGS

[0015] Fig. 1 is a schematic diagram of the three-dimensional structure of the utility model;

[0016] Fig. 2 is a schematic diagram of the internal structure of the utility model;

[0017] Fig. 3 is a schematic diagram of the connection between the gold wire and the detector chip of the utility model;

[0018] Fig. 4 is a schematic diagram of the planar structure of the microlens array layer of the utility model.

[0019] In the drawings, the components represented by each reference number are listed as follows:

[0020] 1, metal shell, 2, tube seat, 3, detector chip, 4, light window, 41, outer layer of flat glass layer, 42, microlens array layer, 5, microlens array, 6, annular welding part, 7, signal pin, 8, ground pin, 9, gold wire. DETAILED DESCRIPTION

[0021] The principles and characteristics of the utility model are described below in combination with the drawings, and the examples are only used to explain the utility model and not to limit the scope of the utility model.

[0022] As shown in the drawing, Figs. 1-4 A photoelectric detector TO packaging structure, comprising a metal shell 1, a light window 4 arranged on the top of the metal shell 1, a tube seat 2 fixed on the bottom of the metal shell 1, and a detector chip 3 arranged on the tube seat 2. The metal shell 1 is used as the main packaging structure and is made of a cylindrical shell body of conductive metal material, has a light-transmitting opening on the top and is fixedly connected with the tube seat 2 on the bottom. A closed cavity is formed in the metal shell 1 to provide electromagnetic shielding and physical protection for the detector chip 3, and the surface of the shell is subjected to electroplating treatment to enhance corrosion resistance. The tube seat 2 is installed on the bottom of the metal shell 1 and is made of ceramic or metal composite material, having high thermal conductivity and insulation properties. The tube seat 2 is provided with a chip mounting area for fixing the detector chip 3 and is integrated with a signal pin 7 and a ground pin 8 to realize electrical connection between the chip electrode and the external circuit. The detector chip 3 is a semiconductor photosensitive element, and its photosensitive surface is fixed on the central area of the tube seat 2. The surface of the chip is protected by a passivation layer, and the edge is provided with a metallized electrode which is connected to the signal pin 7 through a gold wire 9.

[0023] The inner surface of the light window 4 is provided with a microlens array 5, and the focal point of the microlens array 5 coincides with the photosensitive surface of the detector chip 3. The microlens array 5 is composed of a plurality of convex lens units, and each lens unit is arranged in a hexagonal shape. The microlens array 5 has a curvature radius of 0.1-0.5 mm, and the central axis of each lens unit is perpendicular to the photosensitive surface of the detector chip 3. The light window 4 and the metal shell 1 are sealingly connected through an annular welding part 6, and the microlens array 5 is located in the inner side area of the annular welding part 6. The microlens array 5 is etched on the inner surface of the light window 4, i.e. the optical structure of the microlens array layer 42, and covers the light-transmitting area in a closely arranged manner. The central axis of each lens unit is perpendicular to the photosensitive surface of the detector chip 3, and the curvature is designed to make the focal point converge to the center of the chip photosensitive surface.

[0024] The optical window 4 has a double-layer structure, comprising an outer planar glass layer 41 and a microlens array layer 42, which are integrally connected to the outer planar glass layer 41 via a thermoforming process. The optical window 4 covers the light-transmitting component at the top opening of the metal casing 1, and is integrally formed from the outer planar glass layer 41 and the microlens array layer 42 through a thermoforming process. The edge of the optical window 4 is sealed to the metal casing 1 via an annular weld 6, ensuring hermetic sealing. The annular weld 6 is located at the annular metal weld between the outer edge of the optical window 4 and the metal casing 1, and is formed into a continuous sealed structure using laser welding or brazing. The inner side of the annular weld 6 defines the effective working area of ​​the microlens array 5, preventing the heat-affected zone of the weld from interfering with optical performance.

[0025] The socket 2 is also equipped with a signal pin 7 and a ground pin 8. The signal pin 7 is connected to the electrode of the detector chip 3 via a gold wire 9, and the bridging path of the gold wire 9 is located below the focal point of the microlens array 5 to prevent the projection of the gold wire 9 from blocking the incident light. The signal pin 7 and the ground pin 8 pass through the metal conductive terminals of the socket 2. The signal pin 7 is bonded to the electrode of the detector chip 3 via the gold wire 9, and the ground pin 8 is directly connected to the metal shell 1 to achieve electromagnetic shielding. The root of the pin is sealed with glass to ensure airtightness.

[0026] During packaging, the detector chip 3 is first die-bonded to the center of the socket 2, and the chip electrodes and signal pins 7 are interconnected using a gold wire bonding machine. Then, the pre-formed optical window 4 is placed at the top opening of the metal casing 1, with the microlens array layer 42 facing inwards. A laser welding process is used to form a ring-shaped weld 6 along the junction of the optical window 4 and the metal casing 1, achieving a hermetically sealed connection between the optical window 4 and the casing. During welding, a fixture is used to ensure that the central axis of each unit of the microlens array 5 is perpendicularly aligned with the photosensitive surface of the detector chip 3. Finally, the socket 2 is fixed to the bottom of the metal casing 1 by resistance welding, completing the overall package assembly. After filling the package with inert gas, hermeticity testing and optical focus calibration are performed.

[0027] Working principle: the incident light rays pass through the outer layer of plane glass layer 41 into the light window 4, through the refractive effect of the inner layer of microlens array 5, each lens unit converges parallel light to its focal position. Because the focal point of the microlens array 5 coincides with the photosensitive surface of the detector chip 3, the scattered light is refocused to the effective photosensitive area of the chip, improving the utilization of light energy. The hexagonal closely arranged lens unit design makes the light transmission area gapless, eliminating the edge light leakage. The double-layer integrated structure of the light window 4 avoids the refractive index mismatch problem of the bonding interface, reduces the interface reflection loss. The annular welding part 6 seals the package at the same time, and the inner side area limits the effective optical path of the microlens array 5, preventing the welding thermal deformation from affecting the focusing accuracy. The crosslinking path of the gold wire 9 is located below the focal point, which uses the vertical space separation of the chip surface and the gold wire 9 to avoid the shielding of the bonding wire to the incident light. The thermal expansion coefficient of the tube seat 2 and the metal shell 1 is matched, which reduces the thermal stress caused by temperature change, and ensures the long-term alignment stability of the microlens array 5 and the photosensitive surface of the chip.

[0028] The above is only the preferred embodiment of the present application, and is not used to limit the present application, any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A photodetector TO packaging structure, comprising a metal housing (1), an optical window (4) disposed on the top of the metal housing (1), and a tube socket (2) fixed to the bottom of the metal housing (1), wherein a detector chip (3) is disposed on the tube socket (2), characterized in that: The inner surface of the light window (4) is provided with a microlens array (5). The focal point of the microlens array (5) coincides with the photosensitive surface of the detector chip (3). The microlens array (5) is composed of multiple convex lens units, and each convex lens unit is arranged in a hexagon. The light window (4) has a double-layer structure, including an outer planar glass layer (41) and a microlens array layer (42). The microlens array layer (42) and the outer planar glass layer (41) are integrally connected by a hot-melt method. The light window (4) and the metal shell (1) are sealed and connected by an annular welding part (6). The microlens array (5) is located in the inner area of ​​the annular welding part (6).

2. The photodetector TO packaging structure according to claim 1, characterized in that: The microlens array (5) covers the entire light-transmitting area of ​​the light window (4).

3. The photodetector TO packaging structure according to claim 1, characterized in that: The radius of curvature of the microlens array (5) is 0.1~0.5mm, and the central axis of each lens unit is perpendicular to the photosensitive surface of the detector chip (3).

4. The photodetector TO packaging structure according to claim 1, characterized in that: The socket (2) is provided with a signal pin (7) and a ground pin (8). The signal pin (7) is connected to the electrode of the detector chip (3) through a gold wire (9), and the bridging path of the gold wire (9) is located below the focal point of the microlens array (5).

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