High-precision leveling device and leveling method applied to Micro LED mass transfer

Abstract

The invention relates to the technical field of leveling equipment, and provides a high-precision leveling device and leveling method applied to micro LED mass transfer, the high-precision leveling device comprises a temporary substrate and a mounting reference structure, and the temporary substrate is fixed on the lower surface of the mounting reference structure; a lower base plate is arranged above the rotary table, and a plurality of Z-axis displacement tables are installed on the lower base plate; the upper base plate is arranged above the lower base plate, and the Z-axis displacement table is connected with the bottom of the upper base plate; the TFT back plate is mounted on the upper substrate, and the TFT back plate is arranged on the lower side of the temporary substrate; the displacement sensor is installed on the upper base plate and corresponds to the Z-axis displacement table, and the top end of the displacement sensor abuts against the installation reference structure; and the displacement sensor and the TFT backboard are driven by the rotary table to rotate relative to the temporary substrate. By detecting the end face runout of the temporary substrate, the unbalance amount is compensated, and the high-precision leveling effect is achieved.

Description

Technical Field

[0001] The present invention relates to the technical field of leveling equipment, and in particular to a high-precision leveling device and a leveling method for MicroLED mass transfer. Background Art

[0002] MicroLED mass transfer refers to the process of correctly and efficiently moving millions or even tens of millions of micron-sized LED chips to the circuit substrate. This technology is a key step in MicroLED display technology, involving the transfer of chips from a growth substrate (such as a sapphire substrate) to a target substrate (such as a glass TFT substrate). However, transferring millions of micron-sized μLEDs to a driving circuit substrate with high yield, high precision, and high efficiency remains a difficult problem for the industry. During the μLED transfer process, as the transfer area increases (≮6 inches), the parallelism between the TFT backplane and the temporary substrate directly affects the transfer yield.

[0003] At present, the transfer area in the industry is ≯50X50mm, and the transfer alignment accuracy is greater than 10um, so the parallelism requirement between the TFT backplane and the temporary substrate is relatively low, which has a low impact on the transfer yield. As the transfer area increases, the parallelism between the temporary substrate and the TFT backplane directly affects the transfer accuracy. Therefore, a leveling device that can facilitate high-precision adjustment of the TFT backplane and the temporary substrate is designed. Summary of the invention

[0004] The purpose of the present invention is to provide a high-precision leveling device and leveling method for MicroLED mass transfer, which can detect the circular runout of parallel surfaces and compensate for it, so as to achieve high-precision leveling.

[0005] The embodiments of the present invention are realized through the following technical solutions: a high-precision leveling device for MicroLED mass transfer, comprising a temporary substrate and a mounting reference structure, wherein the temporary substrate is fixed to the lower surface of the mounting reference structure; a turntable, wherein a lower substrate is provided above the turntable, and a plurality of Z-axis displacement stages are installed on the lower substrate; an upper substrate, which is provided above the lower substrate, and the Z-axis displacement stage is connected to the bottom of the upper substrate; a TFT backplane, which is installed on the upper substrate, and the TFT backplane is provided on the lower side of the temporary substrate; a displacement sensor, which is installed on the upper substrate and arranged corresponding to the Z-axis displacement stage, and the top of the displacement sensor is in contact with the mounting reference structure; the displacement sensor and the TFT backplane are driven to rotate relative to the temporary substrate by the turntable.

[0006] Furthermore, the installation reference structure includes a first suction cup, and the temporary substrate is adsorbed on the middle part of the first suction cup; a second suction cup is installed on the upper substrate, and the TFT backplane is adsorbed on the second suction cup.

[0007] Furthermore, the lower end surface of the first suction cup is provided with an annular reference surface, and the top end of the displacement sensor abuts against the annular reference surface.

[0008] Furthermore, the installation reference structure also includes a top plate, a base and a support column, the turntable is installed on the base, and both ends of the support column are respectively connected to the top plate and the base; the first suction cup is fixedly connected to the top plate.

[0009] Furthermore, a ball joint structure is provided between the Z-axis translation stage and the upper base plate for connection.

[0010] Furthermore, at least three Z-axis translation stages are provided, and the Z-axis translation stages are evenly spaced and distributed around the middle of the lower substrate.

[0011] Furthermore, a tension spring is connected between the upper substrate and the lower substrate, and the tension spring is arranged close to the Z-axis translation stage.

[0012] A leveling method based on the above-mentioned high-precision leveling device applied to MicroLED mass transfer includes the following steps:

[0013] S1, Debug:

[0014] Adjust the Z-axis translation stage so that the displacement sensor contacts the end surface of the mounting reference structure, and then rotate the turntable one circle;

[0015] Record the runout value of the displacement sensor in one circle and the corresponding runout azimuth, adjust the Z-axis translation stage to ensure that the runout value of one circle is within the detection accuracy of the displacement sensor, and complete the debugging;

[0016] S2, base plate installation:

[0017] The Z-axis translation stage moves with equal position values ​​to install the temporary substrate and TFT backplane at corresponding positions;

[0018] S3, get data:

[0019] The Z-axis translation stage moves to the working position and reads the data of several displacement sensors respectively;

[0020] S4, Leveling:

[0021] The data difference of the displacement sensor is used as the driving value of the Z-axis translation stage to compensate the upper substrate. The upper substrate is driven by the Z-axis translation stage in multiple directions to achieve leveling with different displacement values.

[0022] The technical solution of the embodiment of the present invention has at least the following advantages and beneficial effects: the present invention forms a detection surface through a plurality of displacement sensors, and is driven by a turntable to rotate around the Z axis. By detecting the circular runout of the plane and compensating for the runout value, a high degree of parallelism between the two plates is achieved with higher accuracy. BRIEF DESCRIPTION OF THE DRAWINGS

[0023] In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for use in the embodiments are briefly introduced below. It should be understood that the following drawings only show certain embodiments of the present invention and therefore should not be regarded as limiting the scope. For ordinary technicians in this field, other related drawings can be obtained based on these drawings without creative work.

[0024] Figure 1 A schematic diagram of the structure of a high-precision leveling device for MicroLED mass transfer provided by an embodiment of the present invention;

[0025] Figure 2 A front view of a high-precision leveling device for MicroLED mass transfer in the present invention;

[0026] Figure 3 is an exploded view of the leveling module of the present invention;

[0027] Figure 4 It is a structural schematic diagram of the installation reference structure in the present invention;

[0028] Figure 5 It is a structural schematic diagram when the temporary substrate and the TFT backplane are leveled;

[0029] Figure 6 It is a control schematic diagram of the leveling device in the present invention.

[0030] Icons: 1-installation reference structure, 11-first suction cup, 12-top plate, 13-support column, 14-base, 2-temporary substrate, 3-turntable, 4-lower substrate, 5-Z-axis translation stage, 51-ball joint structure, 6-upper substrate, 61-second suction cup, 7-displacement sensor, 8-TFT backplane, 9-tension spring. DETAILED DESCRIPTION

[0031] In order to make the purpose, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Generally, the components of the embodiments of the present invention described and shown in the drawings here can be arranged and designed in various different configurations.

[0032] Therefore, the following detailed description of the embodiments of the present invention provided in the accompanying drawings is not intended to limit the scope of the invention claimed for protection, but merely represents selected embodiments of the present invention. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0033] It should be noted that similar reference numerals and letters denote similar items in the following drawings, and therefore, once an item is defined in one drawing, further definition and explanation thereof is not required in subsequent drawings.

[0034] Example

[0035] The following is further described in conjunction with specific embodiments. Figure 1-Figure 6 As shown, this embodiment is a high-precision leveling device for MicroLED mass transfer, including a temporary substrate 2 and a mounting reference structure 1, the temporary substrate 2 is fixed to the lower surface of the mounting reference structure 1, that is, the temporary substrate 2 and the mounting reference structure 1 are in a stationary and stable state, that is, the temporary substrate 2 and the mounting reference structure 1 are located in the same plane; a turntable 3, a lower substrate 4 is provided above the turntable 3, and a plurality of Z-axis displacement stages 5 are installed on the lower substrate 4, and the Z-axis displacement stage 5 is located at a corner of the lower substrate 4, which can drive the corner at this position to achieve a slight upward and downward movement; an upper substrate 6, which is provided above the lower substrate 4, and the Z-axis displacement stage 5 is connected to the bottom of the upper substrate 6; a TFT backplane 8, which is installed on the upper substrate 6, and the TFT backplane 8 is provided at the temporary substrate 2 Lower side; displacement sensor 7, which is installed on the upper substrate 6 and arranged corresponding to the Z-axis displacement stage 5, and the top of the displacement sensor 7 is in contact with the installation reference structure 1; the displacement sensor 7 and the TFT backplane 8 are driven to rotate relative to the temporary substrate 2 through the turntable 3; specifically, the turntable 3 can simultaneously drive the upper substrate 6, the lower substrate 4, the Z-axis displacement stage 5 and the TFT backplane 8 to rotate synchronously around the Z-axis, and during one rotation of the turntable 3, the displacement sensor 7 will be driven to detect the end face circular runout of the temporary substrate 2 and the installation reference structure 1 in a rotating state, and the plane where the TFT backplane 8 is located is parallel to the plane where the upper substrate 6 where the displacement sensor 7 is located, and multiple Z-axis displacement stages 5 are controlled to be adjusted according to the detected runout imbalance, so that the parallelism between the TFT backplane 8 and the temporary substrate 2 is improved.

[0036] Knowable Figure 3As shown, the above-mentioned installation reference structure 1 includes a first suction cup 11. Since the temporary substrate 2 is located below the first suction cup 11, a relatively stable and convenient fixing solution is provided. The first suction cup 11 is vacuum adsorbed on the back side of the temporary substrate 2, and the temporary substrate 2 is tightly attached to the surface of the first suction cup 11, and the temporary substrate 2 is adsorbed on the middle part of the first suction cup 11; a second suction cup 61 is installed on the upper substrate 6, and the TFT backplane 8 is adsorbed on the second suction cup 61, and the first suction cup 11, the second suction cup 61, the temporary substrate 2 and the TFT backplane 8 all maintain a highly coaxial state.

[0037] like Figure 6 As shown, an annular reference surface is provided on the lower end surface of the first suction cup 11, and the annular reference surface is ensured to be coplanar with the temporary substrate 2, which can be regarded as the moving trajectory of the displacement sensor 7 during real-time detection of the jump. The top of the displacement sensor 7 is in contact with the annular reference surface. It should be noted that the mounting surface of the displacement sensor 7 is consistent with the adsorption surface of the second suction cup 61 adsorbed on the TFT backplane 8. Therefore, after the displacement sensor 7 is detected and compensated, the parallelism between the mounting surface of the displacement sensor 7 and the annular reference surface reflects the parallelism between the TFT substrate and the temporary substrate 2.

[0038] like Figure 4 As shown, the installation reference structure 1 also includes a top plate 12, a base 14 and a support column 13. The turntable 3 is installed on the base 14. The two ends of the support column 13 are respectively connected to the top plate 12 and the base 14. The support column 13 is located at the four corners of the base 14 to help level the top plate 12, and the support column 13 may have telescopic adjustment capabilities, so that when the first suction cup 11 is fixedly connected to the top plate 12, the installation reference structure 1 completes the rough leveling of the TFT back plate 8 and the temporary substrate 2, and is used in conjunction with the fine leveling of the leveling module.

[0039] In addition, refer to Figure 3 As shown, a ball joint structure 51 is provided between the Z-axis translation stage 5 and the upper base plate 6 for connection. During the leveling process, when the Z-axis translation stage 5 drives the upper base plate 6 to move up and down, based on the ball joint structure 51, the upper base plate 6 has a higher degree of freedom. On this basis, due to the high leveling accuracy requirement, there is also a small gap between the kinematic pairs of the ball joint structure 51. By connecting a tensioning spring 9 between the upper base plate 6 and the lower base plate 4, the elastic tension of the tensioning spring 9 tightens the upper base plate 6 and the lower base plate 4, thereby compensating for the gap. Moreover, the tensioning spring 9 is arranged close to the Z-axis translation stage 5, and the tension of the tensioning spring 9 can maximize the concentrated effect on the ball joint structure 51.

[0040] In this embodiment, at least three Z-axis translation stages 5 are provided to realize three-point leveling, which can be adjusted manually and locked, or electrically controlled, and the Z-axis translation stages 5 are evenly spaced around the middle of the lower substrate 4. The lower substrate 4 is arranged in a triangle, and each Z-axis translation stage 5 is installed exactly at the sharp corner. The vibration of the displacement sensor 7 is analyzed by the translation stage controller, and the vibration difference is used as the driving compensation value to achieve Z-axis displacement consistent with it, thereby ensuring high-precision parallelism between the TFT backplane 8 and the temporary substrate 2.

[0041] In addition, the leveling operation method of the high-precision leveling device applied to MicroLED mass transfer is as follows, which includes the following steps:

[0042] Debugging: adjust the Z-axis translation stage 5 so that the displacement sensor 7 contacts the end face of the installation reference structure 1, and then rotate the turntable 3 for one circle; record the runout value of the displacement sensor 7 for one circle and the corresponding runout azimuth, adjust the Z-axis translation stage 5 to ensure that the runout value for one circle is within the detection accuracy of the displacement sensor 7, and complete the debugging;

[0043] Substrate installation: The Z-axis translation stage 5 performs equidistant position movement to install the temporary substrate 2 and the TFT backplane 8 at corresponding positions;

[0044] Acquiring data: the Z-axis translation stage 5 moves to the working position, and reads the data of several displacement sensors 7 respectively;

[0045] Leveling: The data difference of the displacement sensor 7 is used as the driving value of the Z-axis displacement stage 5 to compensate the upper substrate 6. The upper substrate 6 is driven by the Z-axis displacement stage 5 in multiple directions to achieve leveling with different displacement values.

[0046] In summary, the leveling device and method make installation and inspection easy, the leveling accuracy can reach ±0.5um, the constructed system cost is low, and can be directly applied to the production line.

[0047] The above are only preferred embodiments of the present invention and are not intended to limit the present invention. For those skilled in the art, the present invention may have various modifications and variations. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A high-precision leveling device for MicroLED mass transfer, characterized in that: It comprises a temporary substrate (2) and an installation reference structure (1), wherein the temporary substrate (2) is fixed to the lower surface of the installation reference structure (1); A turntable (3), wherein a lower base plate (4) is provided above the turntable (3), and a plurality of Z-axis displacement stages (5) are mounted on the lower base plate (4); An upper substrate (6) is arranged above the lower substrate (4), and the Z-axis displacement stage (5) is connected to the bottom of the upper substrate (6); A TFT backplane (8) mounted on the upper substrate (6), and the TFT backplane (8) is arranged on the lower side of the temporary substrate (2); A displacement sensor (7), which is mounted on the upper substrate (6) and arranged corresponding to the Z-axis displacement stage (5), and the top end of the displacement sensor (7) is in contact with the mounting reference structure (1); The displacement sensor (7) and the TFT back plate (8) are driven to rotate relative to the temporary substrate (2) by the turntable (3).

2. The high-precision leveling device for MicroLED mass transfer according to claim 1, characterized in that: The installation reference structure (1) comprises a first suction cup (11), and the temporary substrate (2) is adsorbed on the middle part of the first suction cup (11); A second suction cup (61) is mounted on the upper substrate (6), and the TFT back plate (8) is adsorbed on the second suction cup (61).

3. The high-precision leveling device for MicroLED mass transfer according to claim 2, characterized in that: The lower end surface of the first suction cup (11) is provided with an annular reference surface, and the top end of the displacement sensor (7) abuts against the annular reference surface.

4. The high-precision leveling device for MicroLED mass transfer according to claim 2, characterized in that: The installation reference structure (1) further comprises a top plate (12), a base (14) and a support column (13); the turntable (3) is installed on the base (14); and two ends of the support column (13) are respectively connected to the top plate (12) and the base (14); The first suction cup (11) is fixedly connected to the top plate (12).

5. The high-precision leveling device for MicroLED mass transfer according to claim 1, characterized in that: A ball joint structure (51) is provided between the Z-axis displacement stage (5) and the upper base plate (6) for connection.

6. The high-precision leveling device for MicroLED mass transfer according to claim 5, characterized in that: At least three Z-axis translation stages (5) are provided, and the Z-axis translation stages (5) are evenly spaced and distributed around the middle of the lower substrate (4).

7. The high-precision leveling device for MicroLED mass transfer according to any one of claim 6, characterized in that: A tension spring (9) is connected between the upper substrate (6) and the lower substrate (4), and the tension spring (9) is arranged close to the Z-axis displacement stage (5).

8. A leveling method for a high-precision leveling device for MicroLED mass transfer based on any one of claims 1 to 7, characterized in that: The following steps are involved: S1, Debug: Adjust the Z-axis displacement stage (5) so that the displacement sensor (7) contacts the end surface of the mounting reference structure (1), and then rotate the turntable (3) one circle; Record the runout value of the displacement sensor (7) in one circle and the corresponding runout azimuth, adjust the Z-axis displacement stage (5), ensure that the runout value in one circle is within the detection accuracy of the displacement sensor (7), and complete the debugging; S2, base plate installation: The Z-axis displacement stage (5) moves with equal distance displacement values ​​to install the temporary substrate (2) and the TFT back plate (8) at corresponding positions; S3, get data: The Z-axis displacement stage (5) moves to a working position and reads data from a plurality of displacement sensors (7) respectively; S4, Leveling: The data difference of the displacement sensor (7) is used as the driving movement value of the Z-axis displacement stage (5) to compensate the upper substrate (6), and the upper substrate (6) is driven by the Z-axis displacement stages (5) in multiple directions to achieve displacements of different values ​​to complete leveling.

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