Micro-LED repairing and bonding method based on viscoelastic conductive photoresist

Abstract

The invention belongs to the technical field of microelectronic materials, and discloses a Micro-LED repairing and bonding method based on viscoelastic conductive photoresist. According to the method, a conductive photoresist pattern containing conductive nanoparticles, a photoresist matrix, a photosensitive gasified polymer and a viscoelastic polymer is prepared, a repair structure is pushed to be transferred to a bonding pad defect position by utilizing specific wavelength laser to trigger gasification decomposition, and a Micro-LED chip is temporarily fixed by virtue of viscoelasticity; and finally, the permanent bonding of the high-conductivity bonding pad and the chip is formed by heating and curing, so that the industrial pain points of difficulty in repairing the damage of the bonding pad, low precision, poor conductivity and the like in the mass transfer of the Micro-LED are solved. The system integrates a laser repairing module, a positioning calibration module and a thermocuring module, can efficiently repair defects of a driving substrate of a high-density Micro-LED display, remarkably improves the yield and reliability, and is suitable for manufacturing and maintaining Micro-LED displays such as vehicle-mounted displays, wearable equipment and outdoor large-screen displays.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microelectronic materials, and particularly relates to a Micro-LED repairing and bonding method based on a viscoelastic conductive photoresist. BACKGROUND

[0002] With the rapid development of display technology, Micro LED (micro light emitting diode) has become a strong contender for the next generation of display technology with its high brightness, high contrast, low power consumption, long life and fast response, and has shown broad application prospects in many fields such as high-end display, virtual reality, automotive display, etc. In Micro LED display technology, chip bonding and repairing are key links to achieve high-performance display.

[0003] The existing repairing and bonding technology still faces many challenges, and the specific problems are as follows: Traditional Micro-LED bonding technology usually relies on pre-fabricating metal bumps on the pads of the driving backplane, and realizing the interconnection of chips and substrates through hot pressing or reflow soldering. This technical route has many inherent limitations: first, the additional metal bump fabrication link (such as evaporation, electroplating, photolithography, etching) significantly increases the process complexity and manufacturing cost; second, in the process of hot pressing bonding, rigid metal bumps are difficult to effectively buffer stress, which is easy to cause damage or dislocation of micron-level chips, and its bending resistance is also insufficient for flexible display applications. More troublesome is the repairing link. Once the existing bonding materials (such as anisotropic conductive adhesive, thermosetting epoxy resin, etc.) are cured, they form a permanent three-dimensional cross-linked network and cannot be reversed. When a single Micro-LED chip fails, it cannot be removed by local processing, and often has to be discarded as a whole or use extremely complex and low success rate forced measures such as laser ablation, causing huge resource waste and low production efficiency, which has become an insurmountable obstacle for Micro-LED to move towards large-scale production.

[0004] To simplify the process, the industry has explored a method of adding conductive fillers (such as silver nanowires, carbon nanotubes) into photoresist to prepare a conductive adhesive layer. However, such material systems often have difficulty in balancing contradictory performance requirements: to ensure chip fixation and support, the material needs to have high modulus, but this will sacrifice the viscoelastic properties of stress absorption, and after curing, it also faces the fundamental problem of being irreparable. In addition, the uneven dispersion of conductive fillers can easily lead to unstable conductive networks, causing uneven current distribution, pixel brightness fluctuations and other display quality problems. Therefore, developing a new material and method that can simultaneously meet the requirements of high conductivity, dynamic viscoelasticity adaptability, and reversible processability, and realizing compatibility with existing microfabrication processes, has become an urgent need to break through the industrialization barriers of Micro-LED technology.

[0005] The present technology aims to solve the three major bottlenecks of thermal mismatch displacement, secondary bonding yield loss, and high-density pixel alignment accuracy in Micro-LED repair, paving the way for the mass production of Micro-LED in low-thermal-stress processes, flexible wear, high-precision near-eye displays, and high-reliability vehicle screens. SUMMARY

[0006] To solve the problems of Micro LED display technology in the process of mass transfer, bonding and repair in the prior art, the present application provides a Micro-LED repair and bonding method based on viscoelastic conductive photoresist, which fundamentally solves the contradiction between precision and efficiency, temporary fixing and permanent bonding, and repairability in traditional processes. The comprehensive performance advantage provides a reliable technical path for the large-scale application of Micro-LED in high-density integration, flexible display and other frontier fields.

[0007] The technical solution of the present application is as follows: The present application aims to provide a Micro-LED repair and bonding method based on viscoelastic conductive photoresist, comprising the following steps: (1) providing a donor substrate with a viscoelastic conductive repair structure matching the size of the pad; (2) scanning and irradiating the viscoelastic conductive repair structure with a laser beam to trigger the decomposition of photosensitive gasification polymer to produce gas and push the viscoelastic conductive repair structure to separate from the donor substrate; (3) transferring the viscoelastic conductive repair structure to the pad defect position on the driving substrate to complete the repair of the defect position; (4) laser transferring a Micro-LED chip to the surface of the uncured viscoelastic conductive repair structure and temporarily fixing the Micro-LED chip using its viscoelasticity; (5) heating and curing the viscoelastic conductive repair structure to crosslink the viscoelastic conductive repair structure into a pad, thereby realizing permanent bonding of the Micro-LED chip and the pad.

[0008] Preferably, the viscoelastic conductive repair structure in step (1) is prepared from a viscoelastic conductive photoresist by a patterning process, Preferably, the viscoelastic conductive photoresist contains the following components by mass percentage: conductive nanoparticles 10-30 wt%, photoresist matrix 30-40 wt%, azidated polyethylene glycol as photosensitive gasification polymer 5-15 wt%, viscoelastic polymer 10-35 wt%, Irgacure 369 as photoinitiator 3-8 wt%, which is sensitive to 365 nm wavelength and has a 266 nm transmittance ≥ 80%, organic solvent 10-30 wt%.

[0009] Preferably, the conductive nanoparticles are one of gold nanoparticles, anti-oxidation coated copper nanoparticles or ITO nanoparticles, with a particle size ≤ 50 nm.

[0010] Preferably, the photoresist base is SU-8 epoxy resin, with a resolution ≤ 2 μm after 365 nm exposure.

[0011] Preferably, the viscoelastic polymer is polyurethane acrylate (PUA) with a glass transition temperature Tg < 25℃, a molecular weight of 20,000-50,000 Da, a Tg = -10℃-24℃, and a storage modulus G' after curing that is raised to 10 6 -10 7 Pa.

[0012] Preferably, the organic solvent is γ-butyrolactone, propylene glycol methyl ether acetate (PGMEA) or a mixed solvent of the two in a mixing ratio of 1:1.

[0013] Preferably, the wavelength of the laser beam in step (2) is 266 nm, and the energy density of the scanning irradiation is 50-150 mJ / cm².

[0014] Preferably, the Micro-LED chip in step (4) is transferred by ultraviolet laser lift-off; the temporary adhesion after the Micro-LED chip contacts the target pad is ≥ 5 N / cm²; and the chip positioning accuracy is ± 1 μm.

[0015] Preferably, the temperature of the heating and curing treatment in step (4) is 200℃, and the resistivity of the pad formed after curing is ≤ 5×10 -5 Ω·cm, and the Micro-LED chip bonding shear strength is ≥ 20 MPa.

[0016] Compared with the prior art, the present application has the following advantages: 1. The present application creatively uses a 266 nm laser to trigger a non-contact transfer mechanism for the decomposition of a photosensitive gasification polymer to produce gas, which completely avoids mechanical contact compared with the traditional physical compression or thermal expansion transfer method, can achieve ultra-high positioning accuracy of ≤ ± 1 μm, solves the problem of pad position deviation (usually > 5 μm) caused by mechanical contact in the prior art, significantly improves the high-density integration capability of the Micro-LED display, and meets the extreme precision requirements of the super-high resolution Micro-LED display for mass transfer technology.

[0017] 2. The present application optimizes the dispersion of conductive nanoparticles (10-30 wt%) in the SU-8 base and forms a percolation network by 200℃ heat curing, so that the pad resistivity after repair is reduced to ≤ 5×10-5 Ω·cm, the pad resistivity of the traditional repair method (>10 -3 Ω·cm) is improved by two orders of magnitude, effectively ensuring the current injection efficiency and display uniformity of the Micro-LED chip.

[0018] 3, The temporary adhesion of ≥5 N / cm2 is provided by the polyurethane acrylate (PUA) viscoelastic polymer system at room temperature to ensure the fixing of the chip, and the storage modulus is improved to 10 6 -10 7 Pa to form a rigid support, which perfectly solves the contradiction between temporary fixing and permanent bonding in the prior art, and the bonding shear strength can reach ≥20 Mpa, which can provide a solid and reliable mechanical support for the Micro-LED chip, and ensure the stability of the device during long-term work.

[0019] 4, The integrated repair system cooperates with 532 nm laser positioning repair, 266 nm laser transfer and machine vision alignment (accuracy ≤±1 μm), which significantly improves the production efficiency compared with the time-consuming process of traditional single-point repair, and provides a reliable defect repair solution for the large-scale manufacturing of Micro-LED display. BRIEF DESCRIPTION OF DRAWINGS

[0020] Figure 1 The donor substrate with the viscoelastic conductive photoresist bump array described in embodiment 1; Figure 2 The Micro-LED display device schematic diagram with chip missing described in embodiment 1; Figure 3 The laser transfer process schematic diagram of the viscoelastic conductive photoresist bump described in embodiment 1; Figure 4 The laser repair process schematic diagram of the Micro-LED display device described in embodiment 1.

[0021] The marks in the figure represent as follows: 101, Micro-LED display device driving circuit; 102, viscoelastic conductive photoresist bump; 103, Micro-LED display device substrate; 104, Micro-LED chip; 105, donor substrate (COW) originally having Micro-LED chip; 106, laser; 107, donor substrate with viscoelastic conductive photoresist bump array; 108, missing pad on the Micro-LED display device. DETAILED DESCRIPTION

[0022] The present invention will be further described below with reference to preferred embodiments. The endpoints and any values ​​of the ranges disclosed in the present invention are not limited to the precise ranges or values. These ranges or values ​​should be understood to include values ​​close to these ranges or values. For numerical ranges, the endpoint values ​​of the various ranges, the endpoint values ​​of the various ranges and individual point values, and individual point values ​​can be combined with each other to obtain one or more new numerical ranges, which should be regarded as specifically disclosed herein.

[0023] Unless otherwise specified, the experimental methods in the following embodiments are conventional methods, performed in accordance with the techniques or conditions described in the literature in this field or in accordance with the product instructions.

[0024] Unless otherwise specified, all materials and reagents used in the following examples are commercially available.

[0025] Example 1 This embodiment provides a Micro-LED repair and bonding method based on viscoelastic conductive photoresist, including the following steps: (1) The above photoresist is applied through a process of spin coating, pre-baking, exposure, and development, as shown in the example. Figure 1 A viscoelastic conductive repair structure 102 matching the pad size is formed on the donor substrate shown, and it is mounted on the donor substrate 107 mounting stage. The viscoelastic conductive repair structure is fabricated from a viscoelastic conductive photoresist through a patterning process. In this embodiment, the viscoelastic conductive photoresist, by mass percentage, comprises: 10 wt% conductive gold nanoparticles; 30 wt% SU-8 epoxy resin as the photoresist matrix, with a resolution of 2 μm after exposure at 365 nm; 5 wt% photosensitive vaporization polymer azid-modified polyethylene glycol; 35 wt% viscoelastic polymer acrylate with a molecular weight of 20,000 Da and Tg = -10℃; 8 wt% photoinitiator Irgacure 369; and 12 wt% γ-butyrolactone as an organic solvent. The above raw materials are thoroughly mixed to obtain the viscoelastic conductive photoresist. (2) The positioning and calibration system identifies the location of the missing pads on the driving substrate, and uses a 266 nm laser beam to precisely scan and irradiate the viscoelastic conductive repair structure with an energy density of 100 mJ / cm², triggering the decomposition of the photosensitive vaporized polymer to generate gas, which pushes the viscoelastic conductive repair structure away from the donor substrate. The laser-induced pneumatic transfer process is as follows: Figure 2 As shown; (3) The viscoelastic conductive repair structure was captured by a vacuum adsorption device and transferred and fixed with an accuracy of ±2μm under the guidance of a machine vision system. Figure 3The pad defect position 108 on the shown driving substrate 103 is repaired, and the repair of the defect position is completed; (4) The wavelength of the chip laser transfer module is 266 nm. The Micro-LED chip 104 is laser transferred from the donor substrate 105 to the surface of the uncured viscoelastic conductive repair structure by using the ultraviolet laser stripping technology. The temporary fixing of the Micro-LED chip is realized by using the viscosity of the uncured material of the viscoelastic conductive repair structure surface (temporary adhesion force 10 N / cm², chip positioning accuracy ±1 μm). (5) The whole device is placed in a heating and curing module at 200°C, and the viscoelastic conductive repair structure is heated and cured to make the viscoelastic conductive repair structure crosslink and change into a pad, as shown. Figure 4 Finally, the permanent bonding of the Micro-LED chip and the pad is realized.

[0026] In this embodiment, the repair and bonding of the Micro-LED chip are successfully realized by the above method. After testing, the resistivity of the repaired pad is 5×10 -5 Ω·cm, which indicates that the repair structure has excellent conductive performance. At the same time, the chip bonding shear strength reaches 20 MPa, which proves that it has excellent mechanical connection reliability and shear resistance. It can provide strong mechanical support for the Micro-LED chip and effectively prevent the chip from being displaced or falling off due to thermal stress or external force impact during use, meeting the repair requirements of the Micro-LED chip array.

[0027] Embodiment 2 The present embodiment provides a Micro-LED repair and bonding method based on viscoelastic conductive photoresist, which comprises the following steps: (1) The above photoresist is formed into a viscoelastic conductive repair structure matching the size of the pad on the donor substrate by spin coating, pre-baking, exposure, and development processes, and is loaded on the donor substrate loading table; The viscoelastic conductive repair structure is prepared by patterning process of a viscoelastic conductive photoresist. In this embodiment, the raw material composition of the viscoelastic conductive photoresist, calculated by mass percentage, includes: 20 wt% of antioxidant-coated nano-copper particles as conductive nanoparticles; 37 wt% of SU-8 epoxy resin as photoresist matrix, with a resolution of ±1 μm after 365 nm exposure; 10 wt% of azidized polyethylene glycol as photosensitive gaseous polymer; 20 wt% of polyurethane acrylate as viscoelastic polymer, with a molecular weight of 50,000 Da and Tg = 24°C; 3 wt% of Irgacure 369 as photoinitiator; and 10 wt% of γ-butyrolactone as organic solvent; the above raw materials are mixed uniformly to obtain the viscoelastic conductive photoresist; (2) The positioning calibration system identifies the pad defect position on the driving substrate, uses a 266 nm laser beam to accurately scan and irradiate the viscoelastic conductive repair structure at an energy density of 50 mJ / cm2, triggers the decomposition of the photosensitive gasification polymer to produce gas, and pushes the viscoelastic conductive repair structure to separate from the donor substrate; (3) The viscoelastic conductive repair structure is captured by a vacuum suction device and transferred and fixed to the pad defect position on the driving substrate with an accuracy of ±1 μm under the guidance of a machine vision system, completing the repair of the defect position; (4) The wavelength of the chip laser transfer module is 266 nm. The Micro-LED chip is laser transferred from the donor substrate to the surface of the uncured viscoelastic conductive repair structure using the adhesion (temporary adhesion force 8 N / cm2, chip positioning accuracy ±1 μm) of the uncured material on the surface of the viscoelastic conductive repair structure to temporarily fix the Micro-LED chip; (5) The entire device is placed in a heating and curing module at 200°C to heat and cure the viscoelastic conductive repair structure, cross-link the viscoelastic conductive repair structure into a pad, and finally realize permanent bonding of the Micro-LED chip and the pad.

[0028] In this embodiment, a Micro-LED repair and bonding method based on viscoelastic conductive photoresist is used, which is the same as described in Embodiment 1, and will not be described here.

[0029] In this embodiment, the repair and bonding of the Micro-LED chip is successfully realized by the above method. After testing, the resistivity of the repaired pad is 3×10 -5 Ω·cm, indicating that the repair structure has excellent conductive performance, and the chip bonding shear strength reaches 30 MPa, proving its excellent mechanical connection reliability and shear resistance, which can provide strong mechanical support for the Micro-LED chip and effectively prevent the chip from being displaced or falling off due to thermal stress or external impact during use, meeting the repair requirements of the Micro-LED chip array.

[0030] Embodiment 3 This embodiment provides a Micro-LED repair and bonding method based on viscoelastic conductive photoresist, including the following steps: (1) The photoresist is formed on the donor substrate by spin coating, pre-baking, exposure, and development processes to form a viscoelastic conductive repair structure matching the size of the pad, and is loaded on the donor substrate loading table; The viscoelastic conductive repair structure is obtained by a patterning process of a viscoelastic conductive photoresist. In the embodiment, the viscoelastic conductive photoresist is prepared from the following raw materials in percentage by mass: 25 wt% of nano-ITO particles as conductive nanoparticles; 40 wt% of SU-8 epoxy resin as photoresist matrix, the resolution of which is ±1 μm after 365 nm exposure; 5 wt% of azidated polyethylene glycol as photosensitive gasification polymer; 10 wt% of polyurethane acrylate as viscoelastic polymer, the molecular weight of which is 35,000 Da and Tg = 10℃; 5 wt% of Irgacure 369 as photoinitiator; and 15 wt% of γ-butyrolactone as organic solvent; and the raw materials are mixed uniformly to obtain the viscoelastic conductive photoresist. (2) The positioning calibration system identifies the pad defect position on the driving substrate, and a 266 nm laser beam is used to accurately scan and irradiate the viscoelastic conductive repair structure at an energy density of 150 mJ / cm² to trigger the decomposition of the photosensitive gasification polymer to produce gas and push the viscoelastic conductive repair structure to separate from the donor substrate; (3) The viscoelastic conductive repair structure is captured by a vacuum adsorption device and transferred and fixed to the pad defect position on the driving substrate with an accuracy of ±1 μm under the guidance of a machine vision system, thereby completing the repair of the defect position; (4) The wavelength of the ultraviolet laser stripping technology of the chip laser transfer module is 266 nm, which is used to transfer the Micro-LED chip from the donor substrate to the surface of the uncured viscoelastic conductive repair structure, and the temporary fixing of the Micro-LED chip is realized by using the adhesion of the uncured material on the surface of the viscoelastic conductive repair structure (temporary adhesion force 5 N / cm², chip positioning accuracy ±1 μm); (5) The entire device is placed in a heating and curing module at 200℃ to perform heating and curing treatment on the viscoelastic conductive repair structure, so that the viscoelastic conductive repair structure is crosslinked to become a pad, and finally the permanent bonding of the Micro-LED chip and the pad is realized.

[0031] In the embodiment, the Micro-LED repair and bonding method based on the viscoelastic conductive photoresist has the same figures and illustrations as those described in Embodiment 1, which will not be described here.

[0032] In the embodiment, the repair and bonding of the Micro-LED chip are successfully realized by the above method. Tests show that the resistivity of the repaired pad is 1×10 -5The Ω·cm indicates that the repair structure has excellent electrical conductivity. At the same time, the chip bonding shear strength reaches 25 MPa, proving that it has excellent mechanical connection reliability and shear resistance. It can provide robust mechanical support for Micro-LED chips and effectively prevent chip displacement or detachment caused by thermal stress or external impact during use, thus meeting the requirements for Micro-LED chip array repair.

[0033] Example 4 To implement the Micro-LED repair and bonding method based on viscoelastic conductive photoresist described in the above embodiments, this embodiment provides a system based on this method, including: (1) Laser repair module: It is equipped with a laser source with an output wavelength of 532nm, which is used to define the repair position; (2) Pad repair module: It includes a donor substrate loading stage, a 532 nm laser scanning head and a vacuum adsorption transfer device; (3) Chip laser transfer module: Equipped with an ultraviolet laser transfer head with an output wavelength of 266nm, used to directly transfer Micro-LED chips to uncured viscoelastic pads; (4) Thermosetting module: Equipped with a heating device to trigger the cross-linking and curing of the repair structure; (5) Positioning and calibration system: Equipped with a machine vision unit to realize the alignment operation of the whole process, with an alignment accuracy of ≤ ±1 μm.

[0034] Comparative Example 1 This comparative example provides a Micro-LED repair and bonding method based on viscoelastic conductive photoresist, including the following steps: (1) The above photoresist is spin-coated, pre-baked, exposed and developed to form a viscoelastic conductive repair structure matching the pad size on the donor substrate and mounted on the donor substrate mounting stage. The viscoelastic conductive repair structure is fabricated from a viscoelastic conductive photoresist using a patterning process. In this embodiment, the viscoelastic conductive photoresist, by mass percentage, comprises: 5 wt% conductive gold nanoparticles; 30 wt% SU-8 epoxy resin as the photoresist matrix, with a resolution of ±2 μm after exposure at 365 nm; 15 wt% photosensitive vaporization polymer azid-modified polyethylene glycol; 35 wt% viscoelastic polymer urethane acrylate with a molecular weight of 35,000 Da and Tg = 10℃; 5 wt% photoinitiator Irgacure 369; and 10 wt% γ-butyrolactone as an organic solvent. The above raw materials are thoroughly mixed to obtain the viscoelastic conductive photoresist. (2) The positioning and calibration system identifies the location of the missing pads on the driving substrate, and uses a 266 nm laser beam to precisely scan and irradiate the viscoelastic conductive repair structure with an energy density of 150 mJ / cm², triggering the decomposition of the photosensitive vaporized polymer to generate gas, and pushing the viscoelastic conductive repair structure to detach from the donor substrate. (3) The viscoelastic conductive repair structure is captured by a vacuum adsorption device and transferred and fixed to the pad defect position on the drive substrate with an accuracy of ±1μm under the guidance of a machine vision system, thus completing the repair of the defect position. (4) Using the ultraviolet laser stripping technology with a wavelength of 266 nm of the chip laser transfer module, the Micro-LED chip is transferred from the donor substrate to the surface of the uncured viscoelastic conductive repair structure. The adhesion of the uncured material on the surface of the viscoelastic conductive repair structure (temporary adhesion force of 8 N / cm², chip positioning accuracy of 1 μm) is used to temporarily fix the Micro-LED chip. (5) Place the entire device in a heating and curing module at 200°C to heat and cure the viscoelastic conductive repair structure, so that the viscoelastic conductive repair structure is cross-linked and transformed into a pad, and finally achieves permanent bonding between the Micro-LED chip and the pad.

[0035] In this comparative example, the diagrams and illustrations of a Micro-LED repair and bonding method based on viscoelastic conductive photoresist are the same as those described in Example 1, and will not be repeated here.

[0036] In this comparative example, the repair and bonding of the Micro-LED chip were achieved using the method described above. However, due to the low doping ratio of the conductive nanoparticles (5 wt%), the percolation threshold could not be reached after exposure and even thermal curing crosslinking. Testing showed that the resistivity of the repaired pad was 5 × 10⁻⁶. -2 The resistance is too high (Ω·cm), failing to meet the requirements for repairing Micro-LED chip arrays.

[0037] Comparative Example 2 This comparative example provides a method for repairing and bonding Micro-LEDs based on viscoelastic conductive photoresist.

[0038] Unlike Comparative Example 1, the viscoelastic conductive repair structure is fabricated from a viscoelastic conductive photoresist using a patterning process. In this embodiment, the viscoelastic conductive photoresist, by mass percentage, comprises: 10 wt% conductive gold nanoparticles; 30 wt% SU-8 epoxy resin as the photoresist matrix, with a resolution of ±2 μm after exposure at 365 nm; 15 wt% photosensitive vaporization polymer azide-modified polyethylene glycol; 10 wt% viscoelastic polymer polyurethane acrylate with a molecular weight of 60,000 Da and Tg = 30℃; 5 wt% photoinitiator Irgacure 369; and 30 wt% γ-butyrolactone as an organic solvent. The above raw materials are thoroughly mixed to obtain the viscoelastic conductive photoresist. Apart from the above, the remaining steps in this comparative example are the same as those described in Comparative Example 1, and will not be repeated here. In this comparative example, the insufficient addition of viscoelastic polymer resulted in a significant decrease in the viscoelasticity of the prepared conductive photoresist, failing to provide sufficient temporary adhesion and buffering. When the Micro-LED chip was transferred to its surface via laser, the material, due to insufficient mechanical support, could not effectively support and fix the chip, causing chip displacement or detachment, ultimately leading to the failure of the Micro-LED chip array repair process. This result, conversely, confirms that viscoelastic polymers play an indispensable and crucial role in achieving temporary fixation and reliable bonding of chips in the repair method provided by this invention.

[0039] The above description is merely an embodiment of the present invention and does not limit the patent scope of the present invention. Any equivalent structural or procedural transformations made based on the content of the present invention specification, or direct or indirect applications in other related technical fields, are similarly included within the patent protection scope of the present invention.

Claims

1. A method for repairing and bonding a micro-LED based on a viscoelastic conductive photoresist, characterized in that, The method comprises the following steps: (1) providing a donor substrate with a viscoelastic conductive repair structure matching the size of the pad; (2) scanning and irradiating the viscoelastic conductive repair structure with a laser beam to trigger the decomposition of the photosensitive gasification polymer to generate gas and push the viscoelastic conductive repair structure to separate from the donor substrate; (3) transferring the viscoelastic conductive repair structure to the pad defect position on the driving substrate to complete the repair of the defect position; (4) laser transferring a Micro-LED chip to the surface of the uncured viscoelastic conductive repair structure and temporarily fixing the Micro-LED chip by using the viscoelasticity thereof; (5) performing a heating and curing treatment on the viscoelastic conductive repair structure to crosslink the viscoelastic conductive repair structure into a pad, thereby realizing the permanent bonding of the Micro-LED chip and the pad.

2. The method of claim 1, wherein the method is a viscoelastic conductive photoresist-based Micro-LED repair and bonding method. The viscoelastic conductive repair structure in step (1) is prepared by a patterning process of a viscoelastic conductive photoresist.

3. The method of claim 2, wherein the method is a viscoelastic conductive photoresist-based Micro-LED repair and bonding method. The viscoelastic conductive photoresist contains the following components by mass percentage: 10-30 wt% of conductive nanoparticles, 30-40 wt% of a photoresist base, 5-15 wt% of azidated polyethylene glycol as a photosensitive gasification polymer, 10-35 wt% of a viscoelastic polymer, 3-8 wt% of Irgacure 369 as a photoinitiator, and 10-30 wt% of an organic solvent.

4. The method of claim 3, wherein the method is a method for repairing and bonding a micro-LED based on a viscoelastic conductive photoresist. The conductive nanoparticles are one of nano-gold particles, antioxidant-coated nano-copper particles, or nano-ITO particles, and the particle size of the conductive nanoparticles is ≤50 nm.

5. The Micro-LED repair and bonding method based on viscoelastic conductive photoresist as described in claim 3, characterized in that, The photoresist base is SU-8 epoxy resin, and the resolution after 365 nm exposure is ≤2 μm.

6. The method of claim 3, wherein the method is a viscoelastic conductive photoresist-based Micro-LED repair and bonding method. The viscoelastic polymer is polyurethane acrylate, and the molecular weight is 20,000-50,000 Da, and Tg = -10℃-24℃.

7. The method of claim 3, wherein the method is a viscoelastic conductive photoresist-based Micro-LED repair and bonding method. The organic solvent is γ-butyrolactone, propylene glycol methyl ether acetate, or a mixed solvent of the two, and the mixing ratio is 1:

1.

8. The method of claim 1, wherein the method is a viscoelastic conductive photoresist-based Micro-LED repair and bonding method. The wavelength of the laser beam in step (2) is 266 nm, and the energy density of the scanning and irradiation is 50-150 mJ / cm².

9. The method of claim 1, wherein the method is a viscoelastic conductive photoresist-based Micro-LED repair and bonding method. The Micro-LED chip in step (4) is transferred by ultraviolet laser peeling, the temporary adhesion after the contact between the Micro-LED chip and the pad is ≥5 N / cm², and the chip positioning accuracy is ±1 μm.

10. The method of claim 1, wherein the method is a viscoelastic conductive photoresist-based Micro-LED repair and bonding method. The temperature of the heating and curing treatment in step (5) is 200℃.

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