Method for transmitting signals across vacuum for sCMOS image sensor

Abstract

The present application relates to a kind of sCMOS image sensor multi-species signal cross vacuum integration transmission method, comprising: preparation four-layer high-speed vacuum compression flexible circuit board, it includes control signal layer, power loop layer, segmented power layer, high-speed LVDS image data transmission layer from top to bottom;A slit is opened on the bottom disc of vacuum closed cavity, and the middle section of four-layer high-speed vacuum compression flexible circuit board is sealed between the slit and the slit and is penetrated;sCMOS image sensor is connected with the front section of four-layer high-speed vacuum compression flexible circuit board;High-speed high-density rectangular connector is connected with the rear section of four-layer high-speed vacuum compression flexible circuit board;The upper cover of vacuum closed cavity is fixed and sealed with the bottom disc under vacuum condition.This application can ensure the long-term reliability of vacuum cavity, reduce the number of potential leakage points, while having small volume, high space utilization, multi-signal high-quality transmission, simple structure, high reliability, low maintenance and upgrading cost and other advantages.

Description

Methods for integrated transmission of multiple types of signals across vacuum in sCMOS image sensors Technical Field

[0001] This invention belongs to the field of optoelectronic imaging technology, specifically relating to a simple, efficient, and reliable method for cross-vacuum integrated transmission of multiple types of signals from an sCMOS image sensor. Background Technology

[0002] Scientific-grade image sensors, specifically sCMOS image sensors, are widely used in fields such as astronomical observation and life sciences for detecting weak light signals due to their high sensitivity. During use, sCMOS image sensors often require deep cooling to further reduce imaging dark current and enhance detection capabilities. In deep cooling, to prevent water vapor and other impurities in the air from condensing and contaminating the imaging focal plane, the sCMOS image sensor needs to be placed in an airtight cavity. Typical methods for constructing this cavity include filling it with inert gas and evacuating it to a vacuum. The vacuum-sealed cavity method further isolates heat conduction and enhances the depth of cooling, making it the most effective method for deep cooling of sCMOS image sensors. However, the creation and maintenance of the required vacuum environment increases the design complexity. This is because the imaging circuitry and numerous electronic components required for sCMOS image sensors are complex. Constructing a highly reliable vacuum-sealed cavity requires minimizing the number of components inside to reduce the long-term impact of components on maintaining vacuum levels. Ideally, only the sCMOS image sensor should be placed inside the vacuum cavity, while all other peripheral control and processing circuitry should be outside the cavity. However, due to the complex structure and comprehensive functions of sCMOS image sensors, they generally feature numerous signal types and a large number of input / output (IO) pins. For example, the domestically produced high-end sCMOS image sensor GSENSE400 has a total of 114 PGA pins, including analog power supply, digital power supply, pixel power supply, voltage reference source, reference clock, SPI, LVDS, and digital control IO. Directly leading out these diverse, numerous, and differently required pins one by one from the vacuum chamber would undoubtedly increase the number of potential leaks, reduce vacuum reliability, and increase sealing difficulty, making it clearly impractical. Currently, some manufacturers have developed vacuum through-connectors, but using existing vacuum through-connectors is limited by insufficient IO count and large size. Furthermore, for the multi-channel high-speed LVDS transmission technology used in sCMOS image data output (reaching hundreds of megahertz), conventional vacuum through-connectors would severely damage the high-speed signal quality and fail to meet the stringent requirements of sCMOS image sensors. Therefore, how to achieve convenient and efficient cross-vacuum integrated transmission of various signals from sCMOS image sensors, including low-noise power supply and high-speed LVDS image data, is a major problem plaguing relevant practitioners. Summary of the Invention

[0003] The technical problem this invention aims to solve is how to achieve integrated transmission of multiple types of signals from an sCMOS image sensor across a vacuum, including low-noise power supply and high-speed LVDS image data, while ensuring the long-term reliability of the vacuum chamber, reducing the number of potential leaks, and overcoming the problems of traditional conventional vacuum through-connectors being bulky, having limited I / O counts, and failing to guarantee high-speed signal transmission quality. Therefore, the purpose of this invention is to provide a method for integrated transmission of multiple types of signals from an sCMOS image sensor across a vacuum.

[0004] To achieve the above objectives, the present invention adopts the following technical solution:

[0005] A method for integrating and transmitting multiple types of signals across a vacuum using an sCMOS image sensor includes the following steps:

[0006] Step 1: Fabricate a four-layer high-speed vacuum-laminated flexible circuit board. The four-layer high-speed vacuum-laminated flexible circuit board, in its stacked structure, includes, from top to bottom, a control signal layer, a power circuit layer, a split power layer, and a high-speed LVDS image data transmission layer. Each layer is stacked and laminated using a vacuum lamination process, and an electromagnetic shielding film is applied to the upper and lower surfaces after stacking and lamination. In terms of connection sequence, the four-layer high-speed vacuum-laminated flexible circuit board is divided into a front section electrically connected to the sCMOS image sensor, a rear section connected to the high-speed, high-density rectangular connector, and a middle section for transmitting signals from the sCMOS image sensor to the high-speed, high-density rectangular connector.

[0007] Step 2: A slit is made on the chassis of the vacuum-sealed cavity, and the middle section of the four-layer high-speed vacuum-pressed flexible circuit board passes through the slit and is sealed to the slit;

[0008] Step 3: Connect the sCMOS image sensor to the front section of the four-layer high-speed vacuum-bonded flexible circuit board, with both located inside the vacuum-sealed cavity; connect the high-speed, high-density rectangular connector to the rear section of the four-layer high-speed vacuum-bonded flexible circuit board, with both located outside the vacuum-sealed cavity;

[0009] Step 4: Install and seal the top cover of the vacuum-sealed cavity to the chassis under vacuum conditions.

[0010] This invention solves the problem that when sCMOS scientific-grade image sensors are placed in a vacuum-sealed cavity to improve their application performance, it is impossible to achieve effective transmission and efficient integration of large quantities of various types of signals at different rates and various power sources. It has the following beneficial effects:

[0011] (1) The vacuum sealed cavity contains only a single sCMOS image sensor element, while all other drive control systems and required components are located in the normal air environment, which is beneficial to the preparation of the vacuum sealed cavity and the long-term maintenance of the vacuum level.

[0012] (2) The present invention provides a dedicated four-layer high-speed vacuum-pressed flexible circuit board (4-FPC). The dedicated 4-FPC is designed to classify and integrate the transmission of hundreds of signals from sCMOS image sensors. Through a slit in the vacuum-sealed cavity, various signals can be effectively transmitted from sCMOS to the high-speed, high-density rectangular connector, which greatly reduces the potential leakage points in the sealed cavity in the traditional IO through-through method and vacuum through-connector method.

[0013] (3) Compared with traditional FFC, the 4-FPC of the present invention can be stacked in multiple layers, impedance controlled, and shielded to achieve synchronous and effective transmission of various power supplies, low-speed control signals and high-speed LVDS differential signals of hundreds of megahertz. It also has good electromagnetic compatibility, small size and high space utilization.

[0014] (4) For the drive and control system of sCMOS image sensor, all the signals required for its operation are already on the high-speed, high-density rectangular connector in the air environment. All development, testing, modification and upgrading of the imaging system do not require damage or opening of the vacuum sealed cavity. When the vacuum sealed cavity is prepared, a one-time permanent sealing process can be directly adopted without considering the difficulty of subsequent disassembly and assembly and its maintainability. This is conducive to reducing the design difficulty of the vacuum sealed cavity and reducing the cavity volume. Attached Figure Description

[0015] Figure 1 is a flowchart of the method for cross-vacuum integrated transmission of multiple types of signals from an sCMOS image sensor according to the present invention;

[0016] Figure 2 is a schematic diagram of the stacked structure of the four-layer high-speed vacuum-pressed flexible circuit board in this invention and a schematic diagram after stacking and pressing.

[0017] Figure 3 shows the structure of various driving power supplies and high and low speed signals for the sCMOS image sensor.

[0018] Figure 4 is a schematic diagram showing the front, middle and rear sections of the four-layer high-speed vacuum-pressed flexible circuit board in this invention in terms of connection sequence structure.

[0019] Figure 5 shows a comparison of the signal model and physical prototype of the traditional FFC and the 4-FPC of the present invention.

[0020] Explanation of reference numerals in the attached diagram: 1. sCMOS image sensor; 2. Four-layer high-speed vacuum-pressed flexible circuit board; 2-1. Control signal layer; 2-2. Power circuit layer; 2-3. Segmented power layer; 2-4. High-speed LVDS image data transmission layer; 2-5. Electromagnetic shielding film; 3. High-speed high-density rectangular connector; 4. Vacuum sealed cavity. Detailed Implementation

[0021] The present invention will be further illustrated by the following examples, but these examples should not be construed as limiting the scope of protection of the present invention.

[0022] In one embodiment, as shown in FIG1, the present invention provides a method for integrated transmission of multiple types of signals across vacuum in an sCMOS image sensor, the method comprising the following steps:

[0023] Step 1: Prepare a four-layer high-speed vacuum-pressed flexible circuit board 2.

[0024] Referring to Figure 2, in the stacked structure, the four-layer high-speed vacuum-pressed flexible circuit board 2 includes, from top to bottom, a control signal layer 2-1 (i.e., TOP layer), a power circuit layer 2-2 (i.e., L2 layer), a split power layer 2-3 (i.e., L3 layer), and a high-speed LVDS image data transmission layer 2-4 (i.e., BOT layer). The layers are stacked and pressed together using a vacuum pressing process, and the various types of sCMOS signals are distributed on each layer according to the design requirements. Taking the GSENSE400BSI sCMOS image sensor as an example, the hundreds of signals in the integration and stacking of various sCMOS signals are divided into four categories: low-speed control signals, power supply loop GND, various sCMOS drive power supplies, and high-speed LVDS image data signals, as shown in Figure 3. Among them, the low-speed control signals mainly include sCMOS address signals, serial communication signals, timing signals, and system reset signals. The corresponding lines of these signals are distributed on the top layer of the 4-FPC. The power supply loop GND mainly serves as the return path for various sCMOS power supplies, i.e., the drive power supply loop. It is distributed on the L2 middle layer of the 4-FPC, which also provides electromagnetic compatibility. The role of sCMOS is as follows: Various driving power supplies mainly include analog power supplies, digital power supplies, pixel power supplies, and voltage reference sources, with current ranges from 1mA to 500mA. Multiple driving power supply voltage lines and decoupling signal lines are distributed on the L3 segmented power layer, and the area occupied by each power supply on this layer is allocated according to its current magnitude. The high-speed LVDS image data signal is mainly responsible for transmitting the high-speed image data from the sCMOS to the subsequent driving system for acquisition. It also requires serpentine line length adjustment and impedance matching control, distributing it on the bottom layer of the 4-FPC BOT. In addition to the LVDS image data lines, the BOT bottom layer also distributes the input clock signal lines and pixel clock signal lines. In summary, the 4-FPC in this invention consists of four signal stacked layers: the TOP layer is the control signal layer, the L2 layer is the power circuit layer or GND layer, the L3 layer is the split power layer, and the BOT layer is the high-speed LVDS image data transmission layer. After the four signal stacks are pressed together, an electromagnetic shielding film is applied to the upper and lower surfaces of the stacks for further electromagnetic shielding to improve the quality of high-speed LVDS signal transmission. The 4-FPC stacked structure of this embodiment is shown in Figure 2.

[0025] Referring to Figure 4, in terms of connection sequence structure, the four-layer high-speed vacuum-laminated flexible circuit board 2 can be divided into three parts: front section, middle section, and back section. The front section connects to the sCMOS image sensor 1; the middle section is a multi-signal integration and transmission path, integrating hundreds of sCMOS I / Os into a limited number of signal lines. This part crosses the vacuum environment, with its front end connected to the 4-FPC front section and its rear end connected to the 4-FPC back section, transmitting signals from the sCMOS image sensor 1 inside the vacuum chamber to the high-speed, high-density rectangular connector 3 at the back end; the back section connects to the high-speed, high-density matrix connector 3, and through this connector, it makes electrical connections to the subsequent image acquisition and processing board.

[0026] Currently, FFC (Flexible Printed Circuit) is widely used in the development of image sensors both domestically and internationally as the transmission medium for signals inside and outside the cavity. However, it suffers from several problems, including poor high-speed performance, large size, and low space utilization. This is especially true for sCMOS image sensors with hundreds of high-speed I / O pins, where FFC is clearly insufficient to meet the requirements for transmitting various types of signals across a vacuum. Therefore, by analyzing the characteristics of various signals in sCMOS image sensors, this invention proposes a dedicated four-layer high-speed flexible printed circuit board (4-FPC). The layers of the 4-FPC are vacuum-bonded, resulting in superior performance. Furthermore, impedance matching and electromagnetic shielding can be implemented, making it ideal for transmitting high-speed sensitive signals. Moreover, compared to the single-layer, linear arrangement of FFC signals, which results in a large size and a small number of signals, the 4-FPC of this invention allows for multi-layer signal stacking and vacuum bonding, enabling multi-IO transmission in a smaller size. This provides advantages such as small size, high space utilization, and high-quality transmission of multiple signals. Figure 5 shows a comparison of the signal model and physical object of the traditional FFC and the 4-FPC of the present invention. Figure 5(a) shows the comparison of the signal model and physical object of the traditional FFC, and Figure 5(b) shows the comparison of the signal model and physical object of the 4-FPC of the present invention.

[0027] Optionally, the four-layer high-speed vacuum-pressed flexible circuit board 2 in this embodiment adopts four-layer signal stacking, and its overall thickness is 0.5mm.

[0028] Step 2: A slit is made on the chassis of the vacuum sealed cavity 4, and the middle section of the four-layer high-speed vacuum-pressed flexible circuit board 2 passes through the slit and is sealed with the slit.

[0029] Optionally, the chassis of the vacuum sealed cavity 4 is made of all-copper structure with a thickness of 7mm, and a through slit with a width of 1mm is provided on it.

[0030] Optionally, epoxy resin or other materials can be used to seal the through-slit in the middle section of the four-layer high-speed vacuum-pressed flexible circuit board 2.

[0031] Step 3: Connect the sCMOS image sensor 1 to the front section of the four-layer high-speed vacuum-pressed flexible circuit board 2, with both located inside the vacuum-sealed cavity 4; connect the high-speed high-density rectangular connector 3 to the rear section of the four-layer high-speed vacuum-pressed flexible circuit board 2, with both located outside the vacuum-sealed cavity 4.

[0032] In this step, through-hole connections are used to effectively connect all I / O pins of the sCMOS image sensor 1 to the corresponding 4-FPC layers. Both the sCMOS image sensor 1 and the front sections of the four-layer high-speed vacuum-laminated flexible circuit board 2 are located inside the vacuum-sealed cavity 4. The high-speed, high-density rectangular connector 3 is connected to the rear section of the four-layer high-speed vacuum-laminated flexible circuit board 2, and both the high-speed, high-density rectangular connector 3 and the rear section of the four-layer high-speed vacuum-laminated flexible circuit board 2 are located outside the vacuum-sealed cavity 4.

[0033] Step 4: Install and seal the top cover of the vacuum-sealed chamber 4 to the chassis under vacuum conditions. This completes the cross-vacuum integration and transmission of hundreds of different types of signals from the sCMOS image sensor.

[0034] The multi-signal cross-vacuum integrated transmission method proposed in this embodiment is applicable to various types of sCMOS image sensors, such as the GSENSE400 sCMOS image sensor from Changguang Chenxin Technology Co., Ltd., with a data rate of 2.4Gbps. The high-speed, high-density rectangular connector 3 uses the High Density Differential Pair Array connector DPAM-08-07.0-S-8-2-A manufactured by Samtec Corporation, USA. It achieves a maximum transmission rate of 14Gbps and provides up to 144 effective I / Os within a small size of only 24.59mm (length), 21.62mm (width), and 6.66mm (height).

[0035] The proposed method for integrating and transmitting various signals across a vacuum using an sCMOS image sensor enables the use of only a minimal number of components within a vacuum-sealed cavity. Specifically, only the sCMOS image sensor is present, while all other components reside in a normal air environment. This ensures that no other electronic components within the vacuum cavity slowly release gas, preventing a decrease in vacuum level. Furthermore, the sealed cavity contains only a narrow slit, significantly reducing the number of potential leakage points compared to hundreds of I / O through-holes, thus improving the sealing of the vacuum environment and maintaining vacuum levels over the long term. In addition, because this invention categorizes, integrates, and transmits all signals required for the sCMOS image sensor's operation—including analog power, digital power, pixel power, timing control signals, and high-speed LVDS image data signals—it allows for modifications to all drive systems of the sCMOS image sensor without opening or damaging the vacuum cavity. This simplifies subsequent upgrades, debugging, and maintenance of the control and acquisition electronics systems, resulting in a very simple structure, high reliability, and low maintenance and upgrade costs.

[0036] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0037] The embodiments described above are merely illustrative of several implementations of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. A method for integrating and transmitting multiple types of signals across a vacuum using an sCMOS image sensor, characterized in that, The process includes the following steps: Step 1: Prepare a four-layer high-speed vacuum-pressed flexible circuit board (2). The four-layer high-speed vacuum-pressed flexible circuit board (2) includes, from top to bottom, a control signal layer (2-1), a power circuit layer (2-2), a split power layer (2-3), and a high-speed LVDS image data transmission layer (2-4) in the stacked structure. Each layer is stacked and pressed together using a vacuum pressing process, and an electromagnetic shielding film (2-5) is respectively covered on the upper and lower surfaces after stacking and pressing. In terms of connection sequence structure, the four-layer high-speed vacuum-pressed flexible circuit board (2) is divided into a front section that is electrically connected to the sCMOS image sensor (1), a rear section that is connected to the high-speed high-density rectangular connector (3), and a section for transmitting signals from the sCMOS image sensor (1) to the sCMOS image sensor (1). Step 2: A slit is opened on the chassis of the vacuum sealed cavity (4), and the middle section of the four-layer high-speed vacuum-pressed flexible circuit board (2) passes through the slit and is sealed with the slit; Step 3: The sCMOS image sensor (1) is connected to the front section of the four-layer high-speed vacuum-pressed flexible circuit board (2), and the two are located inside the vacuum sealed cavity (4); The high-speed high-density rectangular connector (3) is connected to the rear section of the four-layer high-speed vacuum-pressed flexible circuit board (2), and the two are located outside the vacuum sealed cavity (4); Step 4: The top cover of the vacuum sealed cavity (4) is installed, fixed and sealed to the chassis under vacuum.

2. The method for cross-vacuum integrated transmission of multiple types of signals from an sCMOS image sensor according to claim 1, characterized in that, The middle section of the four-layer high-speed vacuum-pressed flexible circuit board (2) through the slit is sealed with epoxy resin.

3. The method for cross-vacuum integrated transmission of multiple types of signals from an sCMOS image sensor according to claim 1, characterized in that, The thickness of the four-layer high-speed vacuum-pressed flexible circuit board (2) is 0.5 mm.

4. The method for cross-vacuum integrated transmission of multiple types of signals from an sCMOS image sensor according to claim 1, characterized in that, The chassis of the vacuum sealed cavity (4) is made of all copper with a thickness of 7mm, and the slit is 1mm wide.

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