Repair of Micro-LED Displays: A Survey

Efficiently repairing defective pixels in microLED displays using mass transfer of backup chips instead of removing and replacing individual defective pixels. The repair process involves loading main recesses on the substrate with main microLED chips using mass transfer. When all main microLEDs are tested and defective pixels are found, backup microLED chips are mass transferred into the empty backup recesses in the affected subpixels. Since the backup chips match the main chips' color, they can replace defective ones to restore functionality. This reduces repair time compared to removing/replacing single defective pixels.

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A method to repair display devices with defective LED pixels by removing the insulation around the defective pixel and then removing the faulty pixel itself. This allows replacing just the faulty pixel instead of discarding the entire display. The insulation is removed using localized irradiation to access the pixel. This enables repairing display devices with faulty pixels without damaging adjacent pixels.

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Method for repairing display modules with missing LEDs using laser transfer to replace the defective LEDs. The method involves detecting the positions of missing LEDs on the target display substrate, loading it along with a transfer substrate onto stages, arranging them, and moving both stages at constant speed in a row or column direction while transferring a laser consecutively to the missing LED positions. This transfers replacement LEDs from the transfer substrate to the target substrate at the detected missing locations.

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Efficiently repairing defective micro-LEDs in displays. A method for transferring a replacement micro-LED from a donor substrate to the position of a defective LED on the target substrate. The method uses a laser to extract the defective LED from the target substrate, identifies a matching replacement LED on a donor substrate, and then transfers the laser to the identified replacement LED to the vacant position on the target substrate.

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A display panel that can be easily repaired when damaged due to electrostatic discharge (ESD) to reduce display defects. The panel has redundant driving circuits parallel to the primary driving circuits. If a main circuit is damaged, the connecting line to its pixels is opened so the pixels are driven by the redundant circuit instead. This allows repairing a damaged display circuit by rerouting the drive signals through a backup circuit.

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Repairing techniques for micro-LED displays to increase the yield of manufacturing. The techniques involve mapping data from defective subpixels to surrounding spare subpixels to correct display defects without removing and replacing micro-LEDs. The repair can involve mapping defective subpixel colors to spare subpixels using color conversion coatings or filters. The spare subpixels are distributed around the pixel to maintain spatial uniformity.

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Repairing damaged LED chips in a display by replacing them rather than just removing them. The repair method involves using a pick and place module to remove the damaged LED chip, apply a volatile adhesive to the replacement chip, and then heat it to fix it in place. This allows swapping out faulty LEDs without soldering, making chip replacement feasible for repair. The repair is done using a laser to weaken the bond of the damaged chip before removal.

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Method for repairing light emitting device assemblies with missing pixels due to failed transfers. The repair involves transferring functional replacement devices from a source substrate to the backplane at the vacant pixel locations. This involves steps like forming assemblies with the replacement devices, attaching them to temporary carriers, removing them from the source substrate, bonding to the backplane, and removing temporary carriers. This allows repairing imperfect displays with missing pixels from the initial transfer process.

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Reducing defects in micro LED displays through a multi-step repair process during manufacturing. The process involves detecting and replacing defective micro LEDs at three stages: first on the sapphire growth substrate, second on an interposer substrate, and third on the final display backplane. By repairing before transferring to each subsequent substrate, it reduces risk of damage to wiring.

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Repairing defects in emissive displays like microLED displays assembled using fluidic self-assembly. The repair involves inspecting the assembled display to identify defective locations, then selectively removing the defective components like missing, misaligned, or broken LEDs. The inspection uses techniques like UV illumination and filtered imaging to distinguish functional LEDs from defective ones. A robotic pick-and-remove tool handles the defective components without vacuum suction to avoid clogging and slowing due to small port sizes.

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Method of inspecting and replacing micro-LEDs in a display. The method involves temporarily attaching micro-LEDs to a substrate or transfer head, inspecting them for defects, removing any defective ones, and replacing them with normal micro-LEDs. This allows the detection and replacement of defective micro-LEDs before they are permanently attached to the display substrate.

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Micro-LED lighting device with a repair mechanism to improve manufacturing yield and enable in-situ repair. The device has a redundant micro-LED that can be activated if the main micro-LED fails. The redundant LED has separate electrical connections that can be switched on to bypass the main LED. The repair mechanism allows the redundant LED to be activated and connected when the main LED fails, providing a backup lighting source. This allows failed micro-LEDs to be repaired by switching to the redundant LED. The repair mechanism improves yield and product reliability.

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The micro-LED display panel production technique enables the detection and replacement of abnormal micro-LEDs during the transfer process. This simplifies micro-LED repair by detecting LED functionality during transfer. The technique uses a photosensitive conductive bonding layer between the LED and substrate. When the LED emits light, typically, the layer is cured to bond the LED. But if the LED is abnormal, the layer remains uncured, and the LED is not bonded.

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Repair techniques to increase the yield and reduce the cost of emissive displays by identifying and fixing defects in micro-LED displays. The techniques include mapping data from defective sub-pixels to surrounding spare sub-pixels, converting spare sub-pixels to match defective sub-pixel colors, and replacing defective sub-pixels with spare sub-pixels using calculated spatial variations.

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The method for repairing micro-LED components is replacing a defective micro-LED with a known-good one. It involves using a conductive pick-up head to bring the excellent micro-LED into contact with the defective position on the receiving substrate. The pick-up head is bonded to the good LED using a conductive adhesive. Local joule heating is applied through the pick-up head to melt the bonding layer between the good LED and the substrate. The pick-up head is then lifted, leaving the excellent LED in place.

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Micro LED display panel and repair method with individual pixel replaceability to simplify repair and improve success rate. The display has anode electrodes divided into spaced plates connected by lines. Each plate drives a micro LED. If a micro LED fails, the connection line to its plate is cut, leaving the other micro LEDs unaffected. This allows targeted repair without affecting the rest of the display. The cut line clearly identifies the repair location.

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Repairing microLED displays with high yield and efficiency by transferring known-good microLEDs to replace defective ones. The repair process involves: identifying microLED defects on the display, growing replacement microLEDs on a separate substrate, aligning them with the defect locations, and lifting off the replacement microLEDs using laser to transfer them to the display. This avoids contamination of the display surface and simplifies repair compared to picking up individual microLEDs.

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A method for repairing micro LEDs by locally heating and melting the bonding material between the micro LED and substrate using a conductive pick-up head. This allows targeted repair of defective micro LEDs without heating the entire substrate. The method involves bringing the good micro LED on the pick-up head in contact with the faulty position, locally heating the bonding layer through the pick-up head to melt it, then lifting the pick-up head to leave the repaired micro LED on the substrate.

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