Chip pressing machine and chip mass transfer method

Abstract

The present invention discloses a chip point press machine and a chip mass transfer method, comprising a fixed seat, a horizontal movable seat, a vertical movable seat, a voice coil motor, a piezoelectric ceramic actuator and a flexible ejector pin, wherein the horizontal movable seat is slidably connected to the fixed seat, the vertical movable seat is slidably connected to the horizontal movable seat, the voice coil motor is arranged at one end of the fixed seat, the output end of the voice coil motor is connected to the horizontal movable seat, the piezoelectric ceramic actuator is arranged on the vertical movable seat, the top end of the flexible ejector pin is arranged to abut against the telescopic end of the piezoelectric ceramic actuator, and the bottom end of the flexible ejector pin extends to the bottom of the vertical movable seat. The voice coil motor and the piezoelectric ceramic actuator are used as power sources to control the movement of the flexible ejector pin in the x-axis direction and the z-axis direction, respectively, so that the overall system has good system sensitivity, rapidity and adaptability, can better realize high-speed and high-precision transmission control, and make the mass transfer of Micro-LED chips in the z-axis direction faster and more efficient.

Description

Technical Field

[0001] The present invention relates to the field of Micro-LED chip mass transfer, and in particular to a chip pressing machine and a chip mass transfer method. Background Art

[0002] Micro-LED refers to a display technology that uses self-luminous micron-sized LEDs as light-emitting pixel units and assembles them on a driving panel to form a high-density LED array. To make a display, the surface of the chip must be processed into an array structure similar to an LED display, and each pixel must be addressable and individually driven to light up. If driven by a complementary metal oxide semiconductor circuit, it is an active addressing drive architecture, and the Micro-LED array chip and CMOS can be connected through packaging technology.

[0003] The display principle of Micro-LED is to miniaturize, array and thin-film the LED in the structural design, and the size can reach about 1~10μm level; then transfer Micro-LED in batches to the circuit substrate, and the receiving substrate can be a hard or soft transparent or opaque substrate; finally, use the physical deposition method to make a protective layer and add electrodes for packaging, and the simple structure of Micro-LED display can be completed. Because it uses CMOS (Complementary Metal Oxide Semiconductor) integrated circuit technology to make the driving circuit, it realizes the display technology of addressing control and individual driving of each pixel. Compared with LCD and OLED technology, Micro-LED technology has various excellent properties such as high brightness, long life, high contrast, fast response time, high resolution and color saturation, low energy consumption, large viewing angle and high resolution. In addition, it has the advantages of self-luminescence, simple structure, small size and energy saving. It can be used to solve many problems in current display applications, including wearable devices such as mobile phones and tablets. More than 80% of the energy consumption of these devices is on the display. The use of low-energy display technology can provide longer battery life; and strong ambient light will cause the image displayed on the display to be white and the recognition will be poor. The use of high-brightness display technology can make its application scope wider. At present, in the eyes of many manufacturers, this technology has been regarded as the mainstream of the next generation of display technology and has begun to be actively deployed.

[0004] However, in the process of Micro-LED industrialization, a core technical problem that will inevitably be faced is the mass transfer technology; mass transfer, also known as thin film transfer, is the technology of transferring Micro-LED devices to a specific driving substrate and assembling them into a two-dimensional periodic array. Because Micro-LED components are extremely small, the transferred pixels are very large, and the allowable error in the transfer process is extremely small, the transfer accuracy needs to be strictly controlled. In addition, in order to suppress the optical crosstalk between individual pixels and achieve high-quality imaging effects, it is necessary to thin the substrate as much as possible or even peel off the substrate, which further increases the difficulty of the mass transfer solution. In principle, Micro-LED devices require that they must ensure very high efficiency, yield rate and transfer accuracy during the mass transfer process, which makes Micro-LED urgently need to find a better mass transfer process during the research and development process to solve the problem of promoting and using Micro-LED technology.

[0005] According to the current status of technological development, a large number of representative mass transfer technologies have emerged on the market, such as elastomer stamping, electrostatic transfer, electromagnetic transfer, laser-assisted transfer and fluid self-assembly. However, these technologies generally have two problems: time-consuming and high cost, so that no technology has been widely accepted by the industry in terms of various indicators so far. In the most commonly used process, Micro-LED chips are generally grown on round wafers. In the process of mass transfer, the first step is to cut each single Micro-LED chip on the round wafer, and then accurately arrange each cut single Micro-LED chip on the blue film according to the designed integrated circuit spacing size and other parameters, and then all the Micro-LED chips on the blue film are mass transferred at one time to form a target substrate with an integrated circuit. In this way, it is necessary to first cut each Micro-LED chip on the wafer individually, and then arrange them on the blue film in sequence according to the required spacing size on the integrated circuit, and then transfer them to the integrated circuit in mass. This type of method is time-consuming, has low work efficiency and poor alignment accuracy during transfer. Summary of the invention

[0006] The purpose of the present invention is to provide a chip pressing machine and a chip mass transfer method to solve one or more technical problems existing in the above-mentioned background technology.

[0007] To achieve this object, the present invention adopts the following technical solutions:

[0008] A chip point pressing machine comprises a fixed seat, a horizontal movable seat, a vertical movable seat, a voice coil motor, a piezoelectric ceramic actuator and a flexible ejector pin, wherein the horizontal movable seat is slidably connected to the fixed seat, and the vertical movable seat is slidably connected to the horizontal movable seat, the voice coil motor is arranged at one end of the fixed seat, the output end of the voice coil motor is connected to the horizontal movable seat, the piezoelectric ceramic actuator is arranged on the vertical movable seat, the top end of the flexible ejector pin is arranged to abut against the telescopic end of the piezoelectric ceramic actuator, and the bottom end of the flexible ejector pin extends to the bottom of the vertical movable seat; the voice coil motor is used to drive the horizontal movable seat to reciprocate along the x-axis, and the piezoelectric ceramic actuator is used to drive the flexible ejector pin to reciprocate along the z-axis; when the horizontal movable seat moves along the x-axis direction, the vertical movable seat moves synchronously along the z-axis direction.

[0009] Preferably, it also includes a follower rocker, one end of which is hinged to the other end of the fixed base, the other end of which is hinged to the bottom of the vertical movable seat, and there is a height difference between one end and the other end of the follower rocker.

[0010] Preferably, it also includes a flexible amplification mechanism, a motion output end and a ejector pin fixing plate, wherein the flexible amplification mechanism and the motion output end are both arranged at the bottom of the vertical sliding seat, both sides of the motion output end are connected to one end of the flexible amplification mechanism, the top of the motion output end is against the telescopic end of the piezoelectric ceramic actuator, and the flexible ejector pin is connected to the motion output end through the ejector pin fixing plate.

[0011] Preferably, it also includes a tubular slide rail, which is vertically arranged on the horizontal movable seat, and a sliding seat is provided on one side of the vertical movable seat, and the sliding seat is slidably connected to the tubular slide rail.

[0012] Preferably, it further comprises a horizontal slide rail and a sliding block, wherein the horizontal slide rail is horizontally arranged on the fixed seat, the sliding block is arranged on one side of the horizontal movable seat, and the sliding block is slidably connected to the horizontal slide rail.

[0013] The present invention also provides a chip mass transfer method of a chip pressing machine, the method comprising the following steps:

[0014] S1: Arrange the source substrates of Micro-LEDs on the conveyor belt in sequence, and drive them to move at a uniform speed along the x direction;

[0015] S2: By adjusting the corresponding controllers of the voice coil motor and the piezoelectric ceramic actuator respectively, the output thrust and output frequency of the horizontal movable seat, as well as the output thrust and output frequency of the flexible ejector pin are controlled;

[0016] S3: When the source substrate of the Micro-LED is transferred to the bottom of the chip press, the voice coil motor drives the horizontal movable seat to move in the x-axis direction, and the vertical movable seat drives the piezoelectric ceramic actuator and the flexible ejector pin to move along the z-axis direction, so that the piezoelectric ceramic actuator and the flexible ejector pin can quickly and accurately reach the working position;

[0017] S4: The piezoelectric ceramic actuator drives the flexible ejector to move in the z-axis direction to hit the Micro-LED, causing it to fall into the chip receiving platform below. The impact process takes milliseconds. After the impact is completed, the flexible ejector, horizontal movable seat and vertical movable seat return to their original positions and wait for the next Micro-LED chip to be hit. The process is repeated to achieve a massive transfer of Micro-LED chips.

[0018] Preferably, in step S2, the output frequency of the voice coil motor is adjusted so that its movement speed along the x-axis direction is equal to the conveying speed of the conveyor belt.

[0019] Preferably, in step S3, the working position is that the flexible ejector pin and the mass center of the Mirco-LED chip are on the same vertical line.

[0020] Compared with the prior art, the beneficial effects of the present invention are as follows: the present invention adopts a voice coil motor and a piezoelectric ceramic actuator as power sources for controlling the movement of the flexible ejector in the x-axis direction and the z-axis direction respectively, so that the overall system has good system sensitivity, rapidity and adaptability, can better realize high-speed and high-precision transmission control, and can make the mass transfer of Micro-LED chips in the z-axis direction realize mass transfer more quickly and efficiently. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] The accompanying drawings further illustrate the present invention, but the contents in the accompanying drawings do not constitute any limitation to the present invention.

[0022] Figure 1 It is a schematic diagram of the positions of the chip voltage generator and the conveyor belt during mass transfer in one embodiment of the present invention;

[0023] Figure 2 is a schematic diagram of the main structure of a chip voltage generator according to one embodiment of the present invention;

[0024] Figure 3 is a schematic structural diagram of a flexible amplification mechanism of one embodiment of the present invention;

[0025] Figure 4 It is a schematic structural diagram of the top of a chip voltage machine according to one embodiment of the present invention.

[0026] Among them: chip pressing machine 1, conveyor belt 2, Micro-LED chip 3, voice coil motor 11, piezoelectric ceramic actuator 12, follower rocker 13, flexible ejector 14, fixed seat 151, horizontal movable seat 152, vertical movable seat 153, flexible amplifying mechanism 16, ejector fixing plate 161, slider 171, horizontal slide rail 172, tubular slide rail 18. DETAILED DESCRIPTION

[0027] The technical solution of the present invention is further described below with reference to the accompanying drawings and through specific implementation methods.

[0028] A chip pressing machine 1 of this embodiment, referring to the attached Figure 2-4 , including a fixed seat 151, a horizontal movable seat 152, a vertical movable seat 153, a voice coil motor 11, a piezoelectric ceramic actuator 12 and a flexible ejector pin 14. The horizontal movable seat 152 is slidably connected to the fixed seat 151, and the vertical movable seat 153 is slidably connected to the horizontal movable seat 152. The voice coil motor 11 is arranged at one end of the fixed seat 151, and the output end of the voice coil motor 11 is connected to the horizontal movable seat 152. The piezoelectric ceramic actuator 12 is arranged on the vertical movable seat 153. The top end of the flexible ejector pin 14 is arranged to abut against the telescopic end of the piezoelectric ceramic actuator 12, and the bottom end of the flexible ejector pin 14 extends to the bottom of the vertical movable seat 153; the voice coil motor 11 is used to drive the horizontal movable seat 152 to reciprocate along the x-axis, and the piezoelectric ceramic actuator 12 is used to drive the flexible ejector pin 14 to reciprocate along the z-axis; when the horizontal movable seat 152 moves along the x-axis, the vertical movable seat 153 moves synchronously along the z-axis.

[0029] This embodiment uses the voice coil motor 11 as the power source for controlling the movement of the flexible ejector pin 14 along the x-axis direction, and has excellent performance. First of all, the voice coil motor 11 is different from other motors. It adopts a direct drive method, without the need for intermediate links such as screws, gears, and reducers, and largely avoids the problems of reverse clearance, inertia, friction, and insufficient rigidity in the transmission system. Due to the use of direct drive technology, the error caused by the intermediate mechanical transmission system is greatly reduced, so that the system has high accuracy, and the repeated positioning accuracy can be controlled at the micron level, which meets the application of ultra-precision occasions. Secondly, the voice coil motor 11 has the advantages of small size, simple structure, stable force characteristics, easy control, low maintenance cost, safe operation and long service life, and compatibility with multi-brand motion controllers. It can also be used in conjunction with a magnetic suspension rotor, so that the dynamics between the stator and the air gap are always kept contactless, and the fixed and dynamic contact friction is eliminated to a certain extent, so that the overall system has good system sensitivity, rapidity and adaptability, and can better realize high-speed and high-precision transmission control. Based on the characteristics of the voice coil motor 11 such as fast response and smooth movement, it is used to control the movement of the flexible ejector pin 14 along the x-axis direction, which not only meets the requirements of high frequency and high precision in this direction, but also ensures the stability of the entire structure. In addition, the output force of the voice coil motor 11 is related to the coil current, so that the movement trajectory in the x-axis direction is precisely controllable and highly repeatable.

[0030] This embodiment uses a piezoelectric ceramic actuator 12 as a power source to control the movement of the flexible ejector 14 along the z-axis direction, which can make the overall mechanism lighter and simpler. Based on its high frequency, high precision, high repeatability, smooth movement, instant response and other characteristics, the movement of the flexible ejector 14 in the z-axis direction is more accurate, efficient and easier to control. Since the main component of the piezoelectric ceramic actuator 12 is a motor made by using the principle that the shape of piezoelectric materials changes after an electric field is applied. Compared with traditional electromagnetic motors, the structure is smaller and more compact, and the power output is greater in relative size. The efficiency of electromagnetic motors decreases as the size decreases, while the efficiency of piezoelectric ceramic actuators 12 is constant. Under the same volume and weight, the energy storage density of piezoelectric ceramic actuators 12 is 10 times that of electromagnetic motors. The most advanced piezoelectric ceramic actuators 12 can achieve extremely compact and high-speed micro-positioning. Secondly, the principle of direct transmission of the piezoelectric ceramic actuator 12 eliminates the auxiliary transmission parts in traditional electromagnetic motors, avoiding the influence of inter-tooth gaps that greatly reduce the positioning accuracy of electromagnetic servo motors. Furthermore, the piezoelectric ceramic actuator 12 does not require mechanical coupling components, eliminates the inherent jitter of electromagnetic motors, and can be designed to achieve nanometer-level positioning accuracy. In addition, piezoelectric devices can respond within a few microseconds, can achieve accelerations greater than 1500g (response time is in the micrometer level), and do not generate magnetic fields or be affected by electromagnetic interference. It is suitable for most scenarios, has good stability, and has strong instant response capabilities.

[0031] Based on the characteristics of the piezoelectric ceramic actuator 12, such as fast output frequency, high precision and controllable, fast response, strong repeatability and smooth movement, the mass transfer of Micro-LED chips 3 in the z-axis direction can be achieved more quickly and efficiently.

[0032] Preferably, it also includes a follower rocker 13, one end of which is hinged to the other end of the fixed base, and the other end of the follower rocker 13 is hinged to the bottom of the vertical movable seat 153, and there is a height difference between one end and the other end of the follower rocker 13.

[0033] By setting the follower rocker 13, the piezoelectric ceramic actuator 12 and the flexible ejector pin 14 are provided with additional displacement in the z-axis direction, so that they can reach their working positions more quickly and accurately, and have a certain correction effect on the displacement error in the needle direction transmitted from the voice coil motor 11 and generated by the follower rocker 13. At the same time, constraints in the x-axis and z-axis directions are also provided for them, limiting the displacement range in the two directions, ensuring the safe distance between the flexible ejector pin 14 and the conveyor belt 2, and planning a fixed stroke for them, so that the working trajectory of the flexible ejector pin 14 is smoother and more controllable.

[0034] Preferably, it also includes a flexible amplifying mechanism 16, a motion output end and a ejector pin fixing plate 161, the flexible amplifying mechanism 16 and the motion output end are both arranged at the bottom of the vertical sliding seat, both sides of the motion output end are connected to one end of the flexible amplifying mechanism 16, the top of the motion output end is against the telescopic end of the piezoelectric ceramic actuator 12, and the flexible ejector pin 14 is connected to the motion output end through the ejector pin fixing plate 161.

[0035] The setting of the flexible amplification mechanism 16 enables the piezoelectric ceramic actuator 12 to have good performance of slow-release impact and amplification stroke. The flexible amplification mechanism 16 uses the principle of lever to realize the function of motion amplification. The application of the flexible amplification mechanism 16 here can improve the performance of the overall mechanism. Based on its assembly, it can achieve the degree of gap-free, friction-free, and integrated, making the overall motion mechanism more compact and simple. Moreover, only by changing the design of the structure of the flexible amplification mechanism 16, its amplification factor can be changed, thereby changing the motion stroke of the flexible ejector pin 14 it carries. And only by reasonably selecting the processing material, the overall stiffness, natural frequency, stability, mechanical efficiency and other properties of the flexible mechanism can be improved.

[0036] Preferably, it also includes a tubular slide rail 18, which is vertically arranged on the horizontal movable seat 152, and a sliding seat is provided on one side of the vertical movable seat 153, and the sliding seat is slidably connected to the tubular slide rail 18. Therefore, through the cooperation between the sliding seat and the tubular slide rail 18, the movement between the vertical movable seat 153 and the horizontal movable seat 152 is guided, so that when the horizontal movable seat 152 moves in the horizontal direction (x axis), the vertical movable seat 153 moves in the vertical direction (z axis) at the same time under the action of the follower rocker 13, thereby correcting the displacement error generated in the needle direction.

[0037] Preferably, it further comprises a horizontal slide rail 172 and a slider 171, wherein the horizontal slide rail 172 is horizontally arranged on the fixed seat 151, and the slider 171 is arranged on one side of the horizontal movable seat 152, and the slider 171 is slidably connected with the horizontal slide rail 172. Thus, through the cooperation between the slider 171 and the horizontal slide rail 172, the movement between the horizontal movable seat 152 and the fixed seat 151 is guided.

[0038] The present invention applies the basic mechanical transmission principle. Through the power transmission and coordination of the voice coil motor 11 and the piezoelectric ceramic actuator 12, the flexible ejector pin 14 can simultaneously realize high-frequency and high-precision reciprocating motion in the x-axis direction and the z-axis direction. With the flexible amplification mechanism 16 and the follower rocker 13, the overall structure is more stable, reliable, exquisite and simple, and the maintenance difficulty and cost are relatively low. Moreover, since both motors can control the output frequency by adjusting the applied voltage, it overcomes the problems of the traditional mass transfer process being complicated and cumbersome, high production cost, low transfer efficiency and quality, health and safety risks in the production process, and poor user experience.

[0039] This embodiment also provides a chip mass transfer method of the chip pressing machine 1, the method comprising the following steps:

[0040] S1: See attached Figure 1 , arranging the source substrates of the Micro-LEDs on the conveyor belt 2 in sequence, and driving the conveyor belt 2 to move them at a uniform speed along the x direction;

[0041] S2: By adjusting the corresponding controllers of the voice coil motor 11 and the piezoelectric ceramic actuator 12 respectively, the output thrust and output frequency of the horizontal movable seat 152 and the output thrust and output frequency of the flexible ejector pin 14 are controlled;

[0042] S3: When the source substrate of the Micro-LED is transferred to the bottom of the chip pressing machine 1, the voice coil motor 11 drives the horizontal movable seat 152 to move in the x-axis direction, and at the same time, the vertical movable seat 153 drives the piezoelectric ceramic actuator 12 and the flexible ejector pin 14 to move in the z-axis direction under the action of the follower rocker 13, so that the piezoelectric ceramic actuator 12 and the flexible ejector pin 14 can quickly and accurately reach the working position;

[0043] S4: The piezoelectric ceramic actuator 12 drives the flexible ejector pin 14 to move in the z-axis direction to hit the Micro-LED, causing it to fall into the chip receiving platform below. The impact process takes milliseconds. After the impact is completed, the flexible amplifying mechanism 16 resets the flexible ejector pin 14 in the z-axis direction, and the horizontal movable seat 152 and the vertical movable seat 153 return to their original positions under the action of the voice coil motor 11 and the follower rocker 13, waiting for the impact on the next Micro-LED chip 3. The process is repeated to achieve a massive transfer of Micro-LED chips 3.

[0044] Preferably, in step S2 , the output frequency of the voice coil motor 11 is adjusted so that its movement speed along the x-axis direction is equal to the conveying speed of the conveyor belt 2 .

[0045] Preferably, in step S3, the working position is that the flexible ejector pin 14 and the mass center of the Mirco-LED chip are on the same vertical line.

[0046] Thus, when the flexible ejector pin 14 is consistent with the speed of the Micro-LED substrate in the x-axis direction and the flexible ejector pin 14 and the center of mass of the Micro-LED are on the same vertical line, the flexible ejector pin 14 impacts the Micro-LED in the z-axis direction to ensure the accuracy of the impact.

[0047] The technical principle of the present invention is described above in conjunction with specific embodiments. These descriptions are only for explaining the principle of the present invention and cannot be interpreted as limiting the scope of protection of the present invention in any way. Based on the explanations herein, those skilled in the art can associate other specific implementations of the present invention without paying creative labor, and these methods will fall within the scope of protection of the present invention.

Claims

1. A chip pressing machine, characterized in that: The invention comprises a fixed seat, a horizontal movable seat, a vertical movable seat, a voice coil motor, a piezoelectric ceramic actuator and a flexible ejector pin, wherein the horizontal movable seat is slidably connected to the fixed seat, and the vertical movable seat is slidably connected to the horizontal movable seat, the voice coil motor is arranged at one end of the fixed seat, the output end of the voice coil motor is connected to the horizontal movable seat, the piezoelectric ceramic actuator is arranged on the vertical movable seat, the top end of the flexible ejector pin is arranged to abut against the telescopic end of the piezoelectric ceramic actuator, and the bottom end of the flexible ejector pin extends to the bottom of the vertical movable seat; the voice coil motor is used to drive the horizontal movable seat to reciprocate along the x-axis, and the piezoelectric ceramic actuator is used to drive the flexible ejector pin to reciprocate along the z-axis; when the horizontal movable seat moves along the x-axis direction, the vertical movable seat moves synchronously along the z-axis direction; It also includes a flexible amplification mechanism, a motion output end and a pin fixing plate, wherein the flexible amplification mechanism and the motion output end are both arranged at the bottom of the vertical movable seat, both sides of the motion output end are connected to one end of the flexible amplification mechanism, the top of the motion output end is against the telescopic end of the piezoelectric ceramic actuator, and the flexible pin is connected to the motion output end through the pin fixing plate.

2. A chip pressing machine according to claim 1, characterized in that: It also includes a follower rocker, one end of which is hinged to the other end of the fixed seat, the other end of which is hinged to the bottom of the vertical movable seat, and there is a height difference between one end and the other end of the follower rocker.

3. A chip pressing machine according to claim 1, characterized in that: It also includes a tubular slide rail, which is vertically arranged on the horizontal movable seat. A sliding seat is provided on one side of the vertical movable seat, and the sliding seat is slidably connected to the tubular slide rail.

4. A chip pressing machine according to claim 1, characterized in that: It also includes a horizontal slide rail and a slider. The horizontal slide rail is horizontally arranged on the fixed seat, and the slider is arranged on one side of the horizontal movable seat. The slider is slidably connected to the horizontal slide rail.

5. A method for transferring a large number of chips using a chip pressing machine according to any one of claims 1 to 4, characterized in that: The method comprises the following steps: S1: Arrange the source substrates of Micro-LEDs on the conveyor belt in sequence, and drive them to move at a uniform speed along the x direction; S2: By adjusting the corresponding controllers of the voice coil motor and the piezoelectric ceramic actuator respectively, the output thrust and output frequency of the horizontal movable seat, as well as the output thrust and output frequency of the flexible ejector pin are controlled; S3: When the source substrate of the Micro-LED is transferred to the bottom of the chip press, the voice coil motor drives the horizontal movable seat to move in the x-axis direction, and the vertical movable seat drives the piezoelectric ceramic actuator and the flexible ejector pin to move along the z-axis direction, so that the piezoelectric ceramic actuator and the flexible ejector pin can quickly and accurately reach the working position; S4: The piezoelectric ceramic actuator drives the flexible ejector to move in the z-axis direction to hit the Micro-LED, causing it to fall into the chip receiving platform below. The impact process takes milliseconds. After the impact is completed, the flexible ejector, horizontal movable seat and vertical movable seat return to their original positions and wait for the next Micro-LED chip to be hit. The process is repeated to achieve a massive transfer of Micro-LED chips.

6. The method for transferring a large number of chips using a chip pressing machine according to claim 5, characterized in that: In step S2, the output frequency of the voice coil motor is adjusted so that its movement speed along the x-axis direction is equal to the conveying speed of the conveyor belt.

7. The method for transferring a large number of chips using a chip pressing machine according to claim 5, characterized in that: In step S3, the working position is that the flexible ejector pin and the mass center of the Mirco-LED chip are on the same vertical line.

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