Manufacturing Cost Reduction for Micro-LED Displays

Microdisplay chip with precise alignment and reduced volume when transferring LED chips to a PCB. The microdisplay chip has a transfer substrate with grooves for each LED chip. The LED chips are placed in the matching grooves on the transfer substrate. This prevents chip shifting during transfer and ensures accurate alignment when bonded to the PCB. The grooves also limit the LED chip thickness to prevent protrusion from the PCB. The LED epitaxy, current spreading layer, and bonding layers are all contained within the grooves. This reduces the overall display chip size.

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Mass transfer method for LED chips to improve efficiency, yield, and reduce cost compared to using PDMS adhesive. The method involves transferring LED chips from a temporary substrate to a backing substrate without using PDMS. Instead, the LED chips have patterns on sacrificial layers and support layers. The patterns allow breaking the sacrificial layers to release the chips onto the backing substrate. This avoids the need for PDMS and its limitations. The patterns can be made using photoresist layers on the substrates. The LED chips are first transferred onto a temporary substrate with glue, then to a backing substrate with another glue. The sacrificial layers are removed to break the connecting arms between the LED chips and release them onto the backing substrate.

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Method to transfer mini LED chips in high density arrays onto display substrates for mini LED displays with high yield and efficiency. The method involves coating the mini LED chips with a thin film layer and then bonding the film side to a carrier substrate. Liquid silicone is injected between the chips and cured to form a silicone layer. This coated layer can be transferred to the display substrate by peeling it off the carrier. The silicone prevents damage to the mini LED electrodes during transfer. The coated mini LED chips are then aligned and soldered onto the display substrate.

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LED chip assembly, manufacturing method, chip transfer, and display backplane with improved yield, reliability, and flexibility. The LED chips are bonded to a carrier substrate using a sacrificial layer and high-temperature bonding layer instead of organic adhesive. This allows higher temperature processing to create the chips without limiting yield. The sacrificial layer units between chips are covered by a removable barrier layer. During transfer, only the barrier over exposed sacrificial units is removed, allowing selective chip transfer without moving all chips. This provides more compact chip layout and better yield compared to one-to-one correspondence. The display backplane uses these chips to improve yield and reliability.

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Improving the precision of mass transfer of microLEDs by modifying the surface of the chips. A sacrificial passivation layer is added above the bonding pads. The sacrificial layer has a flat surface with uniform characteristics similar to the GaN epitaxial layer. It is roughened to match the roughness of the GaN after laser stripping. This eliminates step and material differences that degrade transfer accuracy. The roughened sacrificial layer provides a consistent surface for adsorption and transfer compared to the GaN surface.

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Micro-LED display with integrated electronics on the same substrate to avoid transfer steps. The microLED chip preparation involves growing the microLED lattice and driving circuit on the same substrate. This allows integrating the microLED display and electronics without transfer steps. The closed linear power supply has the power line encircling the modules to simplify connections.

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Mass transfer method for micro LED displays that improves yield and reduces displacement errors during transfer. The method involves partially etching the original substrate with the micro LED array still attached. Then a temporary substrate is bonded to the micro LED side. Final etching completes the transfer by lifting off the original substrate through the temporary substrate. This sequential etching reduces micro LED loss and displacement compared to direct etching.

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RGB three-color integrated Mini-LED chip, manufacturing method, and display panel that simplify production and packaging of Mini-LED displays. The integrated chip contains all three RGB colors in a single mini LED instead of having separate red, green, and blue mini LEDs for each pixel. This reduces the number of transfer steps and improves yield compared to assembling discrete RGB mini LEDs. The manufacturing method involves growing an epitaxial layer with the three color LED layers stacked vertically. The chip is then diced to separate individual RGB integrated mini LEDs. This allows full-color displays using mini LEDs with simpler and more efficient transfer and assembly compared to discrete RGB mini LEDs.

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A stable and reliable method for transferring microLED chips to a display substrate. The method involves transferring the microLED chips to the substrate while they are still attached to supporting pillars. This prevents poor electrical connections caused by solder overflow. The pillars provide space for the molten solder to surround the microLED without bridging to adjacent devices. The pillars are later removed to leave the microLEDs firmly connected to the substrate. This improves transfer stability and reliability compared to directly transferring bare microLEDs.

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Efficient and accurate transfer of micro LED chips onto a driving substrate for displays using a wafer-level preprocessing and packaging technique. The method involves extracting micro LED crystals from a wafer, placing them into square tubes, arranging the tubes in a pixelated array, cutting the array into sheets, and attaching the sheets to a driving substrate. This allows large numbers of tiny LEDs to be precisely transferred and assembled into displays using a wafer-level packaging process instead of pick-and-place.

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Transferring large numbers of micro LED chips from a growth substrate to a display substrate with improved yield by using a temporary substrate with recessed grooves to hold the micro LED chips. The micro LEDs are first grown on a wafer, then transferred to the temporary substrate with recessed grooves. The wafer substrate is removed, leaving the micro LEDs in the recessed grooves. The temporary substrate with micro LEDs is then transferred to the display substrate. This allows easier pickup and transfer of the micro LEDs due to the recessed grooves.

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A transfer structure and method for precisely moving and transferring micro LED chips to display devices with high efficiency and yield. The structure uses guide rails spaced apart from the transfer substrate with wells between them to accommodate the micro LEDs. This allows the LEDs to be scanned and guided between the rails using a liquid and absorbent material. The spacing between the guide rails is greater than the LED width to allow passage. This fluidic self assembly transfer method enables precise and automated transfer of large numbers of micro LEDs to the display substrate.

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Method for transferring micro LED chips from a growth substrate to a display backplane with improved efficiency and reduced damage compared to traditional methods using masks. The method involves using a transfer template with microstructures on one side. The LED chips are grown on the microstructures. During transfer, a laser removes the chips from the template without a mask. The microstructures prevent lateral forces from flipping or tilting the chips during laser peeling. The microstructures also prevent light from damaging the backplane. This allows direct chip-to-chip transfer without aligning masks.

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A method to transfer LED chips from their growth substrates to a display backplane without offset issues during laser lift-off and transfer. The method involves coating a non-conductive adhesive layer on the display backplane. The LED chips are transferred one at a time from their growth substrates onto the adhesive layer. The adhesive prevents offset during laser lift-off. The LED chips are then electrically connected to the backplane and pressed to form metal eutectic bonds. This allows precise alignment without shifting during transfer.

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A method to transfer micro LED chips from their growth substrate to a display backplane without multiple pick-and-place steps that can misalign the chips. The method involves spreading insulating adhesive between adjacent micro LEDs on the growth substrate. The substrate is then placed above the display backplane with a gap larger than the chip height. The adhesive is heated to soften and flow, connecting the substrate and backplane. The growth substrate is removed, leaving the micro LEDs suspended on the adhesive columns. They fall onto the backplane pads along the column channels. This prevents misalignment and provides a controlled transfer path.

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Mass transfer method for micro LED displays that allows reliable transfer of micro LED chips from growth substrate to display backplane without alignment issues. The method involves filling insulating adhesive between adjacent micro LED chips on the growth substrate, heating to soften and extend the adhesive to the display backplane, separating the micro LED chips from growth substrate, then pressing to drop onto backplane pads via the adhesive column. This prevents misalignment and falling off. The adhesive has shapes like trapezoids or columns with gaps between chip and adhesive to avoid obstruction during bonding.

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Micro-LED chip with stacked LED units to reduce the number of transfers needed to create displays. The chip has two staggered LED units, one stacked on top of the other. This allows three primary colors to be formed by alternating red, green, and blue stacked LEDs instead of transferring three separate monochrome chips for each pixel. The chips have metal backing layers and planarization layers to facilitate manufacturing.

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Method for manufacturing Micro & Mini Micro-pitch LED display modules with very small pixel pitches (less than 0.5 mm) that overcomes limitations of conventional LED display technology. The method involves a unique packaging process using substrates with ball-bonded chips and flip-chip ICs. The display is made by stacking and bonding a top substrate with LEDs and a bottom substrate with flip-chip ICs using solder balls. This allows high-density, ultra-small pitch LED displays to be manufactured without the need for complex multi-layer substrates or physical resolution limits. The method involves steps like silk screening solder paste, soldering balls, applying flux, and reflowing to connect the chips and ICs.

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Manufacturing method for a red light Micro-LED chip that allows creating a substrate-free Micro-LED chip to improve yield and efficiency compared to conventional methods. The method involves growing the red LED structure on a temporary substrate, then transferring it to a receiving substrate using a specialized technique called microtransfer printing. This involves picking up the LED structure using a stamp with suction cups, moving it to the receiving substrate, and releasing it. The stamp conforms to the LED structure shape to avoid damage during transfer. After printing, the temporary substrate is removed, leaving the red Micro-LED chip on the receiving substrate.

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A method to improve transfer efficiency and yield of micro LED displays by transferring multiple colors from a temporary substrate to an array substrate simultaneously instead of separately. This reduces the overall number of micro LED transfers for an array compared to transferring each color separately. By transferring all required colors at once, it eliminates multiple transfers for each color when fabricating the display. This improves transfer efficiency and yield compared to traditional methods that involve multiple transfers for each color.

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