Micro-LED Display Testing and Quality Assurance Techniques

Rapidly verifying many micro-LEDs quickly identifies and removes defective chips. The method uses a wafer-level verification technique, creating an LED verification substrate with contact bumps connecting to the LED chips. The verification substrate containing multiple verification chips is bonded to the LED wafer. Power is applied to the contacts to turn on the LED chips. Any chips that don't emit light are identified as defective and removed.

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An apparatus for inspecting illumination of micro LEDs that addresses the need to efficiently screen and inspect completed micro LEDs before transferring them from a wafer to a target substrate. The apparatus uses a surface-contact probe that touches the front surface of the micro LED assembly and supplies power to the LED ends to turn them on. An imaging unit photographs the LED assembly before and after power is supplied to inspect the overall illumination.

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An apparatus for inspecting the illumination quality of micro LEDs. It uses a surface-contact probe to turn on the micro LEDs and interconnect them, then photographs the lit LED array to inspect their illumination.

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Donor substrates and conductive architectures for on-wafer testing of micro LED display panels. The architectures aim to allow testing of the micro LEDs before transfer to identify good devices. They involve conductive stabilization structures to support and electrically connect the LEDs on the donor substrate. This enables testing of the micro LEDs while still on the donor substrate and prior to transfer to the final display substrate.

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Micro LED display module manufacturing method that improves yield by allowing replacement of defective LEDs before final assembly. The method involves pressurizing the LEDs on the substrate before curing the adhesive layer, to electrically connect them and check their operation. Defective LEDs are identified and replaced with alternatives.

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A method of producing microLED displays that allows efficient and accurate mass transfer of microLED chips onto a display substrate. It involves probing and measuring the chips to create a database of chip characteristics. The chips are then transferred en masse using an expanded tape to match bonding pad spacing. This avoids individual pick-and-place and sorting steps.

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Pick and place apparatus for testing LEDs during production that allows faster and more compact LED testing compared to traditional methods. The apparatus uses a bond head with a translucent portion that allows light from the LEDs to pass through to an optical sensor. This allows the LEDs to be optically tested while they are being picked and placed for electrical testing. The optical characteristics are used to sort the LEDs into bins with similar optical properties. This enables more uniform displays by bonding LEDs from different bins with matching optical characteristics.

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LED manufacturing method that enables testing and repair of small-sized LEDs. The method uses a testing circuit formed on a substrate to electrically connect and test a group of LEDs on the substrate. Any defective LEDs are identified, repaired, or replaced before transferring the suitable LEDs to a target carrier. This allows efficient testing and repair of tiny LEDs, whereas conventional methods are complex due to size constraints.

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Method for inspecting microLED displays to detect defective microLEDs. The method involves sequentially inspecting rows and columns of the microLED array, and determining the coordinates of any defective microLEDs by checking which row and column inspection caused no electrical flow.

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Functionally testing LED devices without direct electrical contact to allow efficient testing of large numbers of LED devices, including micro LED arrays without contacting individual devices. The testing involves injecting current through a capacitor formed using a field plate and dielectric. A voltage ramp drives the electrodes to forward bias the LEDs situated between them, causing a displacement current to flow into the LEDs. The emitted light is measured using cameras above or below the LED substrate to test functionality.

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A method for inspecting and replacing micro LEDs in manufacturing processes like transfer to display substrates. The method involves temporarily attaching the micro LEDs to a substrate or transfer head, inspecting for defects, removing any defective micro LEDs, and replacing them with normal ones before transferring to the final display substrate. This allows detection and replacement of defective micro LEDs during the manufacturing process.

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Micro-LED display panel manufacturing using improved LED probe and transfer methods to enhance yield and throughput. The key steps are probing the LED chips on the wafer to characterize properties and sorting them based on a database, expanding a tape to match substrate pad spacing, and transferring the sorted LED chips to the display panel in one shot. This avoids sequential probing and transfer of individual LED chips.

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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 detection and replacement of defective micro LEDs before they are permanently attached to the display substrate.

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