Micro-LED Display Repair

In this work, the degradation in luminous characteristics of red, green, and blue (RGB) micro-LEDs (10 m 10 m) under electrical stress at 360 K has been investigated. After 280 h aging, AlGaInP-based red exhibit a 31.7% reduction maximum external quantum efficiency, which is significantly greater than reductions observed InGaN-based green micro-LEDs. Specifically, peak wavelength redshift by 0.6 nm, blueshift 1.0 0.5 nm for RGB micro-LEDs, respectively. The color purity decreases 3.6% 0.7%, respectively, resulting 7% gamut.

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A display device with improved yield by sensing and repairing defective subpixels in an LED display. The display has regular subpixels with LEDs and repair subpixels. In the regular subpixels, a sensing layer is placed between the LED and insulation layer. If an LED is not transferred, the sensing layer shorts to the high potential power line. In the repair subpixels, an additional LED is placed on the insulation layer. This allows detecting and repairing subpixel LED non-transfers without full display testing.

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A transparent display module and apparatus with improved manufacturing, inspection, and repairability for self-emitting transparent displays. The module has a grid pattern on a transparent substrate, with micro-pixel ICs and inorganic LEDs placed at the grid intersections. Transparent areas are left between the grids. This allows easier manufacturing, inspection, and repair compared to traditional dense pixel layouts. The transparent areas simplify inspection by providing clear areas to see through the display. The grid pattern allows efficient repair by isolating damaged pixels to just the grid surrounding them.

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Display panel and device design with reversible mini LED soldering for multiple repairs without damaging the substrate. The display uses conductive connectors made of a thermoplastic material with conductive particles distributed in it. These connectors are used to solder mini LEDs to the substrate pads. The thermoplastic property allows easy peeling of LEDs for repairs without damaging the substrate. When cooled, the connectors solidify and hold the LEDs securely. This enables repeat LED replacements without substrate damage.

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Apparatus and method for reworking ultra-small LED chips to quickly and accurately remove defective chips from a substrate and replace them with good chips. The rework involves using transfer technique with stick-shaped detach and attach press heads with adhesive layers of varying strengths. The detach head removes misaligned/defective chips from the weaker first adhesive layer on the substrate to a stronger second adhesive layer. The attach head replaces them from a weaker third adhesive layer onto the first layer. Driving units move the heads above the substrate in X,Y,Z. This allows efficient and precise reworking of ultra-small LED arrays without misalignment issues during chip transfer.

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Self-assembly apparatus for semiconductor microLED displays that allows resolving assembly defects after self-assembly. The apparatus has a fluid chamber to accommodate a fluid and microLEDs. An assembly substrate with electrodes is immersed in the fluid. A magnet array applies a magnetic force to guide microLED assembly. Power is supplied to the electrodes to attract microLEDs. After assembly, a repair substrate with pair electrodes is fed into the fluid. Power is applied to the pair electrodes to attract misplaced microLEDs from the assembly substrate. The repair substrate is then removed. This allows extracting and repositioning misassembled microLEDs without disassembling the display.

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Repairing techniques for micro LED displays to increase yield and reduce cost when defective micro LEDs are found after transfer to the system substrate. The techniques include replacing defective micro LEDs with spare ones, converting color of spares to match defects, mapping spare locations, and spatial coordinate variation to mitigate visual artifacts. It also involves calibration to correct for spatial non-uniformity induced by repair techniques.

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Repairing techniques for micro LED displays to increase yield and reduce costs by leveraging spare devices instead of physical replacement when micro LEDs fail. The repair techniques include remapping data from defective subpixels to surrounding spare subpixels, converting spare subpixels to match defective subpixel colors, and compensating for defective subpixel brightness in spare subpixels. The goal is to improve display quality without adding extra micro LEDs.

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Transferring micro-LEDs using a stamp with shape memory polymer nanotips to pick up and release the devices. The stamp has nanotips that can selectively adhere to the micro-LEDs due to shape memory properties. The nanotips heat to a critical temperature, contact the LED, press to attach, cool below critical temp, align on substrate, then heat again to transfer. This allows precise pickup, placement, and repair of micro-LEDs.

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MicroLED display technology with improved yield and production efficiency by selectively removing defective microLEDs before transfer to the final substrate. The method involves testing the microLEDs on a temporary substrate, removing any failures, and then transferring the remaining good microLEDs to the permanent display substrate. This prevents filling gaps with extra microLEDs, which can have lower yield. The key is controlling the transfer and removal rates so more defective microLEDs are removed than replaced.

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Method for manufacturing LED devices that enables efficient mass transfer, selective transfer, and repair of LEDs between substrates. The process involves attaching the LEDs from a source substrate to a carrier, removing the source substrate, and then transferring a portion of the LEDs from the carrier to the target substrate using laser lift-off. In selective transfer, the laser is focused only on the LEDs to be detached. This allows targeted replacement or repair of LEDs without disturbing the rest.

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An allGaNbased monolithic activematrix microLED system that integrates metalinsulatorsemiconductor highelectronmobility transistors (MIS HEMTs) with lightemitting diodes (LEDs) is demonstrated. The proposed structure employs direct electron injection from the 2D gas (2DEG) in a HEMT, serving as ntype layer, into quantum wells of LEDs. A 2HEMT1LED pixel configuration fabricated one epitaxial growth, enabling precise control LED light output through combination select and drive HEMTs. achieved maximum optical density 0.5 Wcm 2 . 2 matrix constructed row column lines connected via HEMTs, demonstrating capability for individual control.

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Abstract Microlight emitting diode (LED) based LED on silicon (LEDoS) is a promising candidate for nextgeneration AR and VR displays due to superior pixel performance potential high resolution. Traditional RGB pixels are placed single plane, which limits the To overcome this, vertically stacked using heterogeneous monolithic 3D integration (M3D) have been explored. However, previously reported vertical LED not considered heat dissipation capability of pixels, indeed important in future micro displays, utilized materials incompatible with standard CMOS processes, further limiting their practicality LEDoS. The critical regions constraint, bonding medium, typically organic polymer materials. Therefore, handle issue, fullcolor LEDs demonstrated oxide (SiO 2 ) yttrium (Y O 3 ), as mediums. These CMOScompatible offer thermal conductivity at least 10 times higher than conventional polymers. InGaN/GaN blue bonded oxides show improved management, leading external quantum efficiency (EQE) better color characteristics, including narrower full width half maximum (FWHM) purity. ... Read More

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Display device with improved reliability and repairability by preventing or substantially preventing dark spot defects in subpixels. The display has separate first and second conductive patterns that are electrically disconnected from each other. The subpixel electrodes are also disconnected from each other. This allows replacing a reversed connected defective LED without removing it. A laser is used to cut the connections between the electrodes and underlying conductive patterns, then connect them in the correct forward direction. This allows reusing the defective LED by changing its driving current direction. Having multiple sub-electrodes per end of the LED provides redundant current paths to improve reliability.

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Display device with improved transfer process for LED arrays to prevent defects when transferring the LEDs to the display panel. The display device has an adhesive layer on the panel with selective areas that adhere to the LEDs. During transfer, a mask is used to cure and prevent adhesion on the selective areas. This allows transferring only the LEDs in contact with the adhering areas while avoiding transfer of unplaced LEDs. The non-adhering areas provide space for LED repositioning. The adhesive force is higher on the LED contact areas. This prevents transfer defects like LEDs going to wrong positions.

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Transparent display device with improved resolution and repair capability. The display has sub-pixels containing red, green, and blue LEDs, along with a reserve sub-pixel with stacked red, green, and blue LEDs. If any LED in a normal sub-pixel fails, the reserve LEDs can replace them. Stacking the reserve LEDs reduces area compared to parallel LEDs. The reserve LED electrodes are transparent to allow light from lower LEDs to escape. This allows repair and area savings while maintaining light output.

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Display device with easily replaceable parts for improved repairability and recyclability compared to sealed devices. The display has a display panel sandwiched between an inner plate and a support plate. Coupling members connect the inner plate and support plate. This allows disassembly and replacement of just the inner panel or support plate without disturbing the rest of the display. The main frame holds the display panel and has features like guides, fasteners, and a bottom frame for securing the display. This enables easy removal and replacement of just the display panel or inner components, facilitating repair, recycling, and disassembly.

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Flexible electronic device with overlapping bumps for improved repairability of large display tiles. The device has a substrate with adjacent through holes and overlapping bumps. The bumps are adjacent along a direction. The electronic element is overlapped with the substrate and electrically connected to one of the bumps. The distance between the through holes is different from the distance between the bumps in the overlapped direction. This allows replacing a damaged bump without removing the undamaged bump and element. The substrate separates the replaced bump from the element.

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Transfer method for micro flip chips that allows reusing original bonding positions after defective chips are removed. The method uses conductive adhesive as the bonding material between the micro flip chips and substrate. Laser irradiation separates defective chips by causing gasification of the adhesive, without damaging the substrate contacts. The adhesive absorbs laser energy and expands, generating airflow to lift off the chips. This immediate separation prevents contact damage from prolonged laser exposure.

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Micro LED display element with reduced missing pixel defect and improved yield. The element has multiple LEDs packaged together with common electrodes and pads. This allows bonding all LEDs at once instead of separately. The shared electrodes and pads eliminate interference and misalignment issues during die bonding. It also reduces bonding time compared to individual LEDs. The larger element size enables repair through vacuum adsorption holes.

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