Packaging device and packaging method of micro LED chip

Abstract

This invention belongs to the field of semiconductor packaging technology, specifically relating to a packaging device and method for micro LED chips. The method involves a bonding head grasping a micro LED chip array and aligning it with the electrodes of a target substrate. Upon contact, the device senses the contact pressure of each block and independently adjusts the local pressure of the corresponding block to dynamic equilibrium based on pressure deviation. Packaging is then completed through ultrasonic solid-state bonding or thermo-press reflow bonding. The core of the device is a bonding head containing a modular adaptive array. Components include a sealed cavity, a pressure-bearing substrate, an integrated pressure sensor, a micro linear actuator, and control components. A thermal isolation component provides high-temperature protection. This invention achieves adaptive local pressure adjustment of the bonding head, resulting in high pressure adjustment accuracy, stable operation under high-temperature environments, and effective compensation for structural deviations between the chip and the substrate, significantly improving packaging yield while simplifying equipment structure and reducing manufacturing costs.

Description

Technical Field

[0001] This invention belongs to the field of semiconductor packaging technology, and specifically relates to a packaging device and packaging method for a micro LED chip. Background Technology

[0002] Mass transfer and packaging of micro-LED chips is a core technological challenge in manufacturing next-generation microdisplays. This process requires the efficient and high-precision bonding of tens of thousands, or even millions, of micrometer-sized chips to corresponding electrodes on a target substrate. Ensuring the uniformity and adaptability of bonding pressure during this process is crucial for achieving high packaging yields and product reliability.

[0003] In existing technologies, pressure control schemes for micro-LED chip packaging are mainly divided into two categories: passive pressure equalization schemes, such as those using polydimethylsiloxane elastic stamps or homogeneous elastomers, which achieve macroscopic pressure equalization through overall pressurization. This scheme is simple in structure and low in cost, but it cannot cope with local pressure imbalances caused by microscopic differences in the thickness of micro-LED chips, warping of the target substrate, uneven electrode height, or the introduction of tiny foreign objects. This can easily lead to batch solder joint defects or chip breakage, resulting in poor product reliability.

[0004] Active electronic control schemes, such as integrating a multi-channel piezoelectric ceramic actuator array into the bonding head and cooperating with a central controller and a multi-channel force sensor network to achieve closed-loop pressure regulation, have significant drawbacks, despite their ability to achieve precise control. First, the system is complex, requiring large-scale multi-channel signal acquisition, high-speed real-time computation, and precision drive circuitry, resulting in high equipment cost and large size. Second, reliability is poor; multi-channel collaborative operation may lead to signal delays and synchronization errors, and the inherent delay of the electronic control loop is difficult to match the instantaneous dynamic changes at the bonding interface. Third, in bonding processes requiring heat, such as hot pressing or reflow soldering, the dense electronic components are difficult to effectively insulate against heat, easily leading to performance degradation or failure. Therefore, there is an urgent need for a packaging device and method for micro-LED chips. Summary of the Invention

[0005] In view of the above-mentioned shortcomings in the prior art, the present invention provides a packaging device and packaging method for micro LED chips to solve the problems in the background art.

[0006] To solve the above-mentioned technical problems, the present invention adopts the following technical solution: A method for packaging a micro LED chip includes the following steps: Step 1: Using a bonding head with a segmented partitioning structure, the micro-bump array on the lower side of the bonding head's pressure-bearing substrate, which corresponds to the arrangement pattern of the micro-LED chip array, is used to adsorb and grasp the micro-LED chip array, and the micro-LED chip array is aligned with the target substrate electrode. Step 2: Make the micro LED chip array contact the target substrate electrode, and obtain the contact pressure of each block on the bonding head through the sensing link consisting of a sealed cavity configured independently for each block, a fluid medium, and an integrated pressure sensor; the contact pressure is sensed by the pressure change of the fluid medium, and the pressure sensing part of the pressure sensor is in direct contact with the fluid medium. Step 3: Based on the deviation between the contact pressure of each block and the corresponding target pressure, implement independent local pressure adaptive adjustment for each block to achieve dynamic balance in the overall pressure distribution of the micro LED chip array. Step 4: Under dynamic equilibrium, complete the bonding of the micro LED chip to the target substrate to ensure a reliable metallurgical connection between the chip and the substrate electrodes.

[0007] Furthermore, the independent adjustment in step 3 is achieved by adjusting the volume of the sealed cavity corresponding to each block. Decreasing the volume increases the pressure inside the cavity, thereby increasing the chip contact pressure; increasing the volume decreases the pressure inside the cavity, thereby decreasing the chip contact pressure.

[0008] Furthermore, the sealed cavity is controlled by a miniature linear electric actuator; the sealed cavity is filled with a high-temperature stable and incompressible or low-compressibility fluid medium.

[0009] Furthermore, the dynamic balance is that the pressure fluctuation amplitude of all blocks does not exceed ±5% of the preset pressure threshold within 100 milliseconds; after 1000 tests, the metallurgical bonding rate is ≥99% under this fluctuation amplitude.

[0010] Furthermore, the contact pressure in step 2 is sensed by a high-temperature resistant pressure sensor, and the sensing part of the pressure sensor is in contact with the fluid medium in the sealed cavity.

[0011] Furthermore, in step 4, the bonding process involves applying ultrasonic energy to the bonding interface while maintaining dynamic equilibrium pressure to complete solid-phase bonding, or heating the bonding interface with an external heat source under dynamic equilibrium pressure to achieve thermocompression bonding or solder reflow bonding. When thermocompression bonding is used, the sealed cavity, pressure sensor, and control components are provided with thermal insulation protection.

[0012] Furthermore, the pressure transmission path of the sensing link is that the contact pressure between the micro LED chip and the target substrate electrode is transmitted to the sealed cavity through the pressure-bearing substrate, causing the fluid medium inside the cavity to generate a corresponding pressure change. The pressure-sensing part of the integrated pressure sensor is in direct contact with the fluid medium, converting the fluid pressure change into a detectable electrical signal, thereby realizing the sensing of contact pressure.

[0013] Furthermore, a packaging device for a micro LED chip includes a bonding head with a modular adaptive array. The modular adaptive array is composed of multiple relatively independent modular adaptive components, each corresponding to a block on the working surface of the bonding head. The modular adaptive component includes a sealed cavity, a pressure-bearing substrate, an integrated pressure sensor, a micro linear actuator, and a control component. The sealed cavity is made of fluororubber material with a temperature resistance of ≥250℃, and is filled with a low-compressibility fluid medium (such as perfluoropolyether oil) that does not decompose at 200-300℃. The integrated pressure sensor is used to measure the fluid pressure inside the sealed cavity; it converts fluid pressure changes into a linear electrical signal with a pressure-to-electrical-signal conversion coefficient of 0.1-0.5V / N, thereby achieving accurate sensing of contact pressure. The output of the miniature linear electric actuator is connected to the sealed cavity via a transmission connection, which is used to change the volume of the cavity. The control unit is electrically connected to the miniature linear electric actuator and is used to control the operation of the miniature linear electric actuator based on the deviation between the fluid pressure and the target pressure.

[0014] Furthermore, the control component is isolated from the high-temperature environment by a thermal isolation assembly, which includes a vacuum insulation layer (quartz glass material) with a thickness of 1.0-2.0 mm and an aerogel insulation pad with a thermal conductivity of ≤0.02 W / (m・K) and a thickness of 0.8-1.5 mm. Testing showed that when the bonding interface temperature is 250℃, the operating temperature of the control component is ≤80℃, and there is no performance degradation of the sensor and actuator.

[0015] Furthermore, the lower surface of the pressure-bearing substrate is provided with a micro-bump array corresponding to the arrangement pattern of the micro LED chip array. The control components of the block adaptive component constitute a distributed control node, with each node operating independently and processing the pressure sensing and adjustment of its block in parallel.

[0016] Compared with the prior art, the present invention has the following beneficial effects: This invention utilizes a modular distributed pressure control architecture to divide the bonding head working surface into multiple independent and controllable blocks. Each block is equipped with a complete pressure sensing and adjustment unit, enabling independent adaptive adjustment of local pressure in each block. Compared to passive pressure equalization schemes, it can accurately compensate for pressure imbalances caused by microscopic factors such as chip thickness differences and substrate warping, significantly improving packaging yield. Compared to active electronic control schemes, it uses distributed control nodes to replace complex central control systems, avoiding multi-channel signal delays and synchronization errors, greatly improving response speed, while simplifying equipment structure and reducing manufacturing costs, achieving a balance between precise control and simplified structure. This invention divides the bonding head into ≥10 independent controllable blocks, utilizes hydrostatic pressure transmission and a micro linear electro-actuator to achieve local pressure adaptive adjustment, with pressure fluctuation amplitude not exceeding ±5% within 100 milliseconds, improving packaging yield to over 99%, and can work stably in a high-temperature environment of 250℃, effectively compensating for pressure imbalance caused by chip thickness differences and substrate warping, while simplifying equipment structure and reducing manufacturing costs. Based on the principle of hydrostatic pressure transmission and combined with the precise driving characteristics of a micro linear electro-actuator, rapid response and stable transmission of pressure regulation are achieved. The high-temperature resistant design of the fluid medium and core components, along with thermal isolation components, enables the device to operate stably for a long time in a high-temperature bonding environment, avoiding component aging, medium leakage or performance failure caused by high temperature. The micro-bump array design on the lower surface of the pressure-bearing substrate not only ensures the stability of chip gripping, but also achieves uniform pressure transmission, further improving the reliability of the package connection. The modular design avoids the extreme complexity caused by setting actuators for individual chips, while providing much finer control granularity than global pressure equalization. Combined with a micro-bump array, it can effectively ensure pressure uniformity within a block, compensate for pressure differences between different blocks in parallel and independently, and achieve highly uniform bonding that takes into account both macro and micro aspects. Attached Figure Description

[0017] Fig. 1 This is a flowchart of a packaging method for a micro LED chip according to the present invention; Fig. 2 This is a cross-sectional view of the block adaptive component structure; Fig. 3 This is a schematic diagram of a micro-LED chip array on a target substrate. The reference numerals in the accompanying drawings include: 1. Target substrate; 2. Chip block; 3. Micro LED chip; 4. Block adaptive component; 41. Sealed cavity; 42. Fluid medium; 43. Pressure-bearing substrate; 44. Air suction channel; 45. Pressure sensor; 46. Micro linear electro-actuator; Detailed Implementation

[0018] To enable those skilled in the art to better understand the present invention, the technical solution of the present invention will be further described below in conjunction with the accompanying drawings and embodiments.

[0019] The accompanying drawings are for illustrative purposes only and are schematic diagrams, not actual images. They should not be construed as limiting the scope of this application. To better illustrate the embodiments of the present invention, some parts in the drawings may be omitted, enlarged, or reduced, and do not represent the actual dimensions of the product. It is understandable to those skilled in the art that some well-known structures and their descriptions may be omitted in the drawings.

[0020] In the accompanying drawings of the embodiments of the present invention, the same or similar reference numerals correspond to the same or similar components. In the description of the present invention, it should be understood that if terms such as "upper," "lower," "left," "right," "inner," and "outer" indicate the orientation or positional relationship based on the orientation or positional relationship shown in the drawings, they are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, the terms used to describe positional relationships in the drawings are only for illustrative purposes and should not be construed as limiting the present application. For those skilled in the art, the specific meaning of the above terms can be understood according to the specific circumstances.

[0021] In the description of this invention, unless otherwise explicitly specified and limited, the term "connection" or similar designation indicating a connection between components should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral part; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication between two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this invention based on the specific circumstances.

[0022] Example 1: As Figs. 1-3 As shown, the present invention discloses a method for packaging a micro LED chip, comprising the following steps: Step 1: Using a bonding head with a segmented partitioning structure, the micro-bump array on the lower side of the bonding head's pressure-bearing substrate, which corresponds to the arrangement pattern of the micro-LED chip array, is used to adsorb and grasp the micro-LED chip array, and the micro-LED chip array is aligned with the target substrate electrode. Specifically, the bonding head uses a motion platform and a vision positioning system to align the micro LED chip array with the target substrate electrodes, ensuring that the alignment deviation between the blocks and the corresponding electrode areas meets the bonding process requirements.

[0023] Step 2: Make the micro LED chip array contact the target substrate electrode, and obtain the contact pressure of each block on the bonding head through the sensing link consisting of the independently configured sealed cavity of each block, the fluid medium and the integrated pressure sensor; the contact pressure is sensed by the pressure change of the fluid medium, and the pressure sensing part of the pressure sensor is in direct contact with the fluid medium.

[0024] Specifically, the drive bonding head moves smoothly downward, causing the pads of the micro LED chip array to make initial contact with the target substrate electrodes. At this time, the integrated pressure sensors of each block's adaptive components are activated. Through the pressure change of the fluid medium in the sealed cavity, the contact pressure of the chip in the corresponding block is indirectly obtained. The fluid pressure and the direct contact pressure have a linear relationship, and the pressure is transmitted to the control components.

[0025] Step 3: Based on the deviation between the contact pressure of each block and the corresponding target pressure, implement independent local pressure adaptive adjustment for each block to achieve dynamic balance in the overall pressure distribution of the micro LED chip array. Specifically, the control components of each block will sense the fluid pressure and compare it with a preset target pressure, where the preset target pressure is set according to the chip size and solder characteristics. If the sensed fluid pressure is lower than the target pressure, the control components will drive the micro linear electro-actuator to extend and squeeze the sealed cavity to reduce its volume. Due to the incompressibility or low compressibility of the fluid medium in the cavity, the reduction in volume will directly lead to an increase in the cavity pressure. This pressure will be transmitted to the pressure-bearing substrate through hydrostatic pressure, which will push the microbump array to increase the contact pressure on the chip in the corresponding block. If the sensed fluid pressure exceeds the target pressure, the control unit drives the miniature linear electro-actuator to retract, releasing the sealed cavity and increasing its volume. This reduces the pressure inside the cavity, causing the pressure-bearing substrate to slightly retract under the chip's reaction force. The micro-bump array reduces the contact pressure on the chips within the corresponding blocks. All blocks complete the sensing-comparison-adjustment closed-loop operation in parallel and independently until the pressure distribution of the entire micro-LED chip array reaches dynamic equilibrium.

[0026] Step 4: Under dynamic equilibrium conditions, complete the bonding of the micro-LED chip to the target substrate, ensuring a reliable metallurgical connection between the chip and the substrate electrodes. Bonding is achieved by applying ultrasonic energy to the bonding interface while maintaining dynamic equilibrium pressure to complete solid-state bonding, or by heating the bonding interface with an external heat source under dynamic equilibrium pressure to achieve thermocompression bonding or solder reflow bonding. When using thermocompression bonding, thermal insulation protection is provided for the sealed cavity, pressure sensor, and control components.

[0027] Specifically, the bonding method is selected based on the chip type and process requirements; ultrasonic solid-state bonding, for thermistor chips such as those with built-in photosensitive elements and low-temperature resistant chips, applies ultrasonic energy to the bonding interface while maintaining dynamic equilibrium, using vibrational mechanical energy to break down the interface oxide layer, promote metal atom diffusion, and form a solderless metallurgical bond; hot pressing or solder reflow, for chips with solder bumps, heats the bonding interface to the solder melting point through an external heat source, while a thermal isolation component protects the sealed cavity, sensor and its control components, achieving solder melting and reflow for metallurgical connection under balanced pressure; after bonding is completed, the control component drives the electric actuator to reset, and the bonding head detaches from the chip array.

[0028] The criteria for determining the dynamic equilibrium state is that the fluctuation range of the fluid pressure of all block adaptive components does not exceed ±5% of the preset pressure threshold within a predetermined time (e.g., within 100 milliseconds).

[0029] Select micro LED chips and target substrates from the same batch, build a test platform, and perform trial packaging by changing the pressure. If the packaged chips show poor soldering, it indicates that the pressure is below the threshold and the baseline value needs to be increased. If the chips are damaged, it indicates that the pressure is above the threshold and the baseline value needs to be decreased. If the connection is reliable, the current pressure is used as the initial baseline value. Perform small-batch packaging according to the initial baseline value, and count the poor soldering rate and the breakage rate. If the poor soldering rate is >1%, increase the baseline value by 5%-10%; if the breakage rate is >0.5%, decrease the baseline value by 5%-10%. If the chip batch, solder type, or bonding method is changed, the above test needs to be repeated and the threshold value recalibrated.

[0030] The specific experiments were as follows: 1μm micro LED chips from the same batch were selected and packaged at pressures of 0.5N, 1.0N, 1.5N, 2.0N, 2.5N, and 3.0N. At 0.5N, significant solder joint defects appeared, indicating the pressure was below the threshold and the baseline value needed to be increased. At 1.0N, solder joint defects still occurred, indicating the pressure was still below the threshold and needed further increase. At 1.5N, the metallurgical bonding rate reached 98.5%, with no solder joint defects or chip breakage, and the connection was reliable; this pressure was determined as the initial baseline value. At 2.0N, there were no solder joint defects but a small number of chip breaks occurred, indicating the pressure was above the threshold and the baseline value needed to be decreased. At 2.5N and 3.0N, chip breakage worsened, indicating the pressure was far above the threshold and the baseline value needed to be significantly decreased. After packaging 1000 chips in a small batch at the initial baseline value of 1.5N, the solder joint defect rate was 0.8% and the breakage rate was 0.3%, both below the set standards, and no adjustment of the baseline value was needed.

[0031] During the packaging process, if the pressure sensor detects that the pressure in a certain area frequently exceeds the fluctuation threshold (such as due to continuous high pressure caused by substrate warping), the target pressure reference value of that area can be finely adjusted individually by the control component to ensure overall balance.

[0032] Furthermore, a packaging device for micro LED chips includes a bonding head made of a material with a low coefficient of thermal expansion to ensure structural stability during bonding and avoid positional displacement caused by temperature changes. Its working surface is arranged with multiple adaptive block components according to the partitioning pattern of the electrodes on the target substrate 1. Each adaptive block component includes a sealed cavity 41, a pressure-bearing substrate 43, an integrated pressure sensor 45, a micro linear actuator 46, and a control component. The adaptive block components employ distributed independent control. For an array of 10,000 chips, the working surface of the bonding head is divided into 200 blocks, with each block corresponding to 50 chips. For an array of 50,000 chips, it is divided into 500 blocks, with each block corresponding to 100 chips. Each chip block 2 contains 50 micro LED chips.

[0033] Specifically, the miniature linear electric actuator 46 is connected to the sealed cavity 41 via a threaded drive; the air suction channel 44 is perpendicularly connected to the pressure-bearing substrate 43; the volume of the sealed cavity 41 is 1-5μL; the thickness of the pressure-bearing substrate 43 is 2-3mm; and the pressure-sensing part of the integrated pressure sensor 45 is in direct contact with the fluid medium inside the sealed cavity 41.

[0034] The sealed cavity 41 can be made of high-temperature resistant fluororubber or silicone rubber, with a temperature resistance of not less than 250℃, to ensure the consistency of sealing performance and deformation at high temperatures; the cavity is filled with perfluoropolyether oil or fluorinated liquid, such fluid medium 42 does not decompose and has low expansion at 200-300℃, ensuring the stability of pressure transmission.

[0035] The pressure-bearing substrate 43 is connected to the lower surface of the sealed cavity 41 and is used to support the micro LED chip 3 in a block. The lower surface of the pressure-bearing substrate 43 is provided with a micro bump array corresponding to the array arrangement pattern of the micro LED chip 3. The lower surface of the pressure-bearing substrate 43 is ultra-precision polished and a micro bump array adapted to the array arrangement pattern of the micro LED chip 3 is prepared by micro-etching process. The height of the bumps meets the chip support and gripping requirements and realizes uniform pressure transmission.

[0036] An integrated pressure sensor 45 is used to measure the fluid pressure inside a sealed cavity 41. Specifically, the pressure sensor 45 can be a piezoresistive MEMS pressure sensor 45, with the pressure-sensing part in direct contact with the fluid medium 42 to ensure the accuracy of pressure measurement under high-temperature conditions.

[0037] The output of the miniature linear actuator 46 is connected to the sealed cavity 41 for changing the volume of the cavity. Specifically, the miniature linear actuator 46 and the sealed cavity 41 are connected by a threaded drive, and the air suction channel 44 is perpendicularly connected to the pressure-bearing substrate 43. The miniature linear actuator 46 adopts a piezoelectric ceramic linear motor, and its stroke and response speed meet the requirements of cavity volume adjustment, realizing precise pressure fine adjustment. Its shell is made of heat-insulating material to reduce high temperature conduction. The chip is electrically connected to the sensor and actuator through fine gold wires to realize signal transmission and control command output.

[0038] The control unit is electrically connected to the miniature linear actuator 46 and is used to control the operation of the miniature linear actuator 46 based on the deviation between the fluid pressure and the target pressure. The control unit is isolated from the high-temperature environment by a thermal insulation component, which includes a vacuum insulation layer (quartz glass) with a thickness of 1.0-2.0 mm and an aerogel insulation pad (0.8-1.5 mm thick) with a thermal conductivity ≤0.02 W / (m・K). Testing shows that when the bonding interface temperature is 250℃, the operating temperature of the control unit is ≤80℃, and there is no performance degradation of the sensor and actuator. The control unit integrates a pressure signal processing module, a control algorithm module, and a power drive module, encapsulated in a high-temperature resistant ceramic shell. The vacuum insulation layer is located between the control unit, the sensor, and the bonding head body to block heat conduction. The insulation pad covers the sealed cavity 41, the sensor, and the actuator, creating an effective temperature difference between the unit's interior and the bonding interface, ensuring that the internal components are not affected during high-temperature bonding.

[0039] Example 2: The micro LED chip packaging device includes a target substrate support platform, a high-precision motion platform, a vision positioning system, and a core bonding head. The bonding head body is made of Invar steel, and its working surface is arranged with adaptive block components according to the electrode partitioning pattern of the target substrate. The number of blocks is set according to the chip array size, with each block corresponding to multiple micro LED chips. The adaptive block components include a sealed cavity made of fluororubber, filled with perfluoropolyether oil to ensure sealing performance and pressure transmission stability at high temperatures; a pressure-bearing substrate made of sapphire, with a micro-bump array on its lower surface having bump heights of 5-10 μm and diameters of 2-3 μm, with spacing consistent with the pad spacing of the micro LED chips (10-20 μm), prepared using ultra-precision polishing and micro-etching processes to ensure chip support stability and uniform pressure transmission; an integrated pressure sensor using a piezoresistive MEMS pressure sensor, with range and resolution adapted to the bonding pressure measurement requirements; and a micro linear actuator using a piezoelectric ceramic linear motor, with stroke and response speed meeting the cavity volume adjustment requirements.

[0040] The vacuum insulation layer, in conjunction with the aerogel insulation pad, enables temperature difference control between the unit's interior and the bonding interface. The vacuum insulation layer, made of highly transparent, high-temperature resistant quartz glass with a thickness of 1.0-2.0 mm, is positioned between the control components, integrated pressure sensor, miniature linear actuator, and bonding head body. The aerogel insulation pad, made of silica aerogel with a thermal conductivity not exceeding 0.02 W / (m·K) and a thickness of 0.8-1.5 mm, tightly covers the outer wall of the sealed cavity, the exterior of the integrated pressure sensor, and the output end of the miniature linear actuator. Its extremely low thermal conductivity blocks heat conduction while also providing some elasticity to absorb stress caused by cavity deformation.

[0041] The packaging process of micro LED chips is as follows: the bonding head moves to the location of the micro LED chip array and uses the micro-bump array on the lower surface of the pressure substrate to adsorb and fix the chip array; then it is transferred to the target substrate, and the vision positioning system completes the precise alignment of the chip array with the electrodes of the target substrate to ensure that the alignment deviation meets the process requirements.

[0042] The drive bonding head moves downward at a steady speed of 0.1-0.3 mm / s to avoid impact that could damage the chip or cause pressure sensing deviation. This allows the chip pads to make initial contact with the target substrate electrodes. The contact pressure is transmitted through the pressure-bearing substrate to the perfluoropolyether oil in the sealed cavity, causing a corresponding pressure change in the fluid. The integrated pressure sensors in each block are activated, capturing the fluid pressure changes in real time at a set sampling frequency and converting them into electrical signals, which are then transmitted to the control components to complete the accurate sensing of the contact pressure.

[0043] The control unit compares the acquired fluid pressure electrical signal with a preset target pressure: if the fluid pressure is lower than the target pressure, the control unit drives a miniature linear actuator to extend, compressing the sealed cavity to reduce its volume, thereby increasing the fluid pressure inside the cavity. This pressure is then transmitted to the pressure-bearing substrate through the fluid medium, increasing the chip contact pressure. If the fluid pressure is higher than the target pressure, the control unit drives the miniature linear actuator to retract, releasing the sealed cavity to increase its volume, reducing the fluid pressure inside the cavity, and decreasing the chip contact pressure. All blocks are adjusted in parallel until the fluid pressure fluctuation of all blocks does not exceed a reasonable range within a preset pressure threshold within a preset time, achieving dynamic pressure equilibrium.

[0044] The external hot stage is activated to heat the bonding interface to the solder melting point. The thermal isolation component controls the internal temperature of the unit below the component's tolerance temperature to prevent high temperature from affecting the performance of the sensing link and control components. The set time is maintained under balanced pressure to complete the solder reflow and metallurgical connection. Then the hot stage cools down to room temperature at a set speed, the micro linear actuator is reset, the bonding head is detached from the chip array, and the packaging process is completed.

[0045] The above are merely embodiments of the present invention. The circuits, electronic components, and modules involved are all prior art, fully achievable by those skilled in the art, and require no further explanation. The content protected by this application does not involve improvements to the software and methods. Commonly known structures and characteristics in the solutions are not described in detail here. Those skilled in the art are aware of all common technical knowledge in the field prior to the application date or priority date, are able to access all prior art in that field, and have the ability to apply conventional experimental methods prior to that date. Those skilled in the art can, under the guidance of this application, improve and implement this solution in combination with their own capabilities. Some typical known structures or methods should not be obstacles for those skilled in the art to implement this application. It should be noted that those skilled in the art can make several modifications and improvements without departing from the structure of the present invention. These should also be considered within the scope of protection of the present invention, and will not affect the effectiveness of the implementation of the present invention or the practicality of the patent.

Claims

1. A method for packaging a micro LED chip, characterized in that: Includes the following steps: Step 1: Using a bonding head with N independent controllable blocks, where N is a positive integer ≥10, the micro-bump array corresponding to the arrangement pattern of the micro-LED chip array on the lower side of the pressure-bearing substrate of the bonding head is used to adsorb and grasp the micro-LED chip array, and the micro-LED chip array is aligned with the target substrate electrode. Step 2: Make the micro LED chip array contact the target substrate electrode, and obtain the contact pressure of each block on the bonding head through the sensing link consisting of the independently configured sealed cavity of each block, the fluid medium and the integrated pressure sensor. Contact pressure is sensed by the pressure change of the fluid medium, and the pressure sensing part of the pressure sensor is in direct contact with the fluid medium; Step 3: Based on the deviation between the contact pressure of each block and the corresponding target pressure, implement independent local pressure adaptive adjustment for each block to achieve dynamic balance in the overall pressure distribution of the micro LED chip array. Step 4: Under dynamic equilibrium, complete the bonding of the micro LED chip to the target substrate to ensure a reliable metallurgical connection between the chip and the substrate electrodes.

2. The packaging method for a micro LED chip as described in claim 1, characterized in that: The independent adjustment in step 3 is achieved by adjusting the volume of the sealed cavity corresponding to each block. Decreasing the volume increases the pressure inside the cavity, thereby increasing the chip contact pressure; increasing the volume decreases the pressure inside the cavity, thereby decreasing the chip contact pressure.

3. The packaging method for a micro LED chip as described in claim 2, characterized in that: The sealed cavity is controlled by a miniature linear electric actuator; the sealed cavity is filled with a high-temperature stable and incompressible or low-compressibility fluid medium.

4. The packaging method for a micro LED chip as described in claim 1, characterized in that: The dynamic balance is defined as the pressure fluctuation amplitude of all blocks not exceeding ±5% of the preset pressure threshold within 100 milliseconds.

5. The packaging method for a micro LED chip as described in claim 1, characterized in that: The contact pressure in step 2 is sensed by a high-temperature resistant pressure sensor, and the sensing part of the pressure sensor is in contact with the fluid medium in the sealed cavity.

6. The packaging method for a micro LED chip as described in claim 1, characterized in that: In step 4, bonding is achieved by applying ultrasonic energy to the bonding interface under pressure that maintains dynamic equilibrium, thus completing solid-phase bonding, or by heating the bonding interface with an external heat source under pressure that maintains dynamic equilibrium, thus achieving hot-press bonding or solder reflow bonding. When hot-press bonding is used, the sealed cavity, pressure sensor, and control components are provided with thermal insulation protection.

7. The packaging method for a micro LED chip as described in claim 1, characterized in that: In step 2, the pressure transmission path of the sensing link is that the contact pressure between the micro LED chip and the target substrate electrode is transmitted to the sealed cavity through the pressure-bearing substrate, causing the fluid medium in the cavity to generate a corresponding pressure change. The pressure sensing part of the integrated pressure sensor is in direct contact with the fluid medium, converting the fluid pressure change into a linear electrical signal. The pressure-to-electrical signal conversion coefficient is 0.1-0.5V / N, realizing accurate sensing of contact pressure.

8. A packaging apparatus for a micro LED chip, applicable to the packaging method for a micro LED chip as described in claims 1-7, characterized in that: The device includes a bonding head with a modular adaptive array. The modular adaptive array is composed of multiple relatively independent modular adaptive components, each of which corresponds to a block on the working surface of the bonding head. The modular adaptive components include a sealed cavity, a pressure-bearing substrate, an integrated pressure sensor, a miniature linear electric actuator, and control components. The sealed cavity is made of fluororubber material with a temperature resistance of ≥250℃, and is filled with a low-compressibility fluid medium that does not decompose at 200-300℃. The pressure-bearing substrate is connected to the lower surface of the sealed cavity and is used to support the micro LED chip in a block. The integrated pressure sensor is used to measure the fluid pressure inside the sealed cavity; it converts fluid pressure changes into a linear electrical signal with a pressure-to-electrical-signal conversion coefficient of 0.1-0.5V / N, thereby achieving accurate sensing of contact pressure. The output of the miniature linear electric actuator is connected to the sealed cavity via a transmission connection, which is used to change the volume of the cavity. The control unit is electrically connected to the miniature linear electric actuator and is used to control the operation of the miniature linear electric actuator based on the deviation between the fluid pressure and the target pressure.

9. The packaging device for a micro LED chip as described in claim 8, characterized in that: The control component is isolated from the high-temperature environment by a thermal isolation assembly, which includes a vacuum insulation layer made of high-transmittance, high-temperature resistant quartz glass with a thickness of 1.0-2.0 mm, and a silica aerogel insulation pad with a thickness of 0.8-1.5 mm and a gas thermal conductivity ≤0.02 W / (m・K).

10. The packaging apparatus for a micro LED chip as described in claim 8, characterized in that: The lower surface of the pressure-bearing substrate is provided with a micro-bump array corresponding to the arrangement pattern of the micro LED chip array. The control components of the block adaptive component constitute a distributed control node, with each node operating independently and processing the pressure sensing and adjustment of its block in parallel.

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