KR102042179B1 - Pick-and-remove system and method for emissive display repair - Google Patents

Abstract

The present invention provides a system and method for restoring a light emitting display. After assembly, the light emitting substrate is inspected to determine the defective array position, and the defective item is removed using an adsorption and removal process. In one aspect, the light emitting substrate comprises one well, and the light emitting elements are arranged in the well, but are not electrically connected to the light emitting substrate. If the light emitting device is a light emitting diode (LED), the light emitting substrate may be exposed to ultraviolet light to photoexcite the LED array, so that the LED mask is measured to determine the defective array position. Defective items may be misaligned, misplaced, or determined as invalid light emitting elements or debris. After the identification of these defective items, the defective items are removed using an automatic adsorption and removal process. Adsorption and removal processes can be repurposed to fill empty wells with replacement light emitting devices.

Description

PICK-AND-REMOVE SYSTEM AND METHOD FOR EMISSIVE DISPLAY REPAIR}

The present invention relates to a fluid assembled light emitting display, and more particularly to a system and method for restoring a light emitting display.

Current competitive technologies for large size displays are liquid crystal displays (LCDs), organic light emitting device (OLED) displays and recent inorganic LED displays. Disadvantages of LCDs directly addressed by this application are 1) low efficiency where only about 5% of the light generated by the backlight is shown to the user as an image, and 2) low dynamic range in which the LC material cannot completely block light and produce black pixels. to be. The disadvantage of OLED displays is the low reliability and low efficiency of the blue OLED material (~ 5% quantum efficiency (QE)). The use of inorganic micro-LEDs (μLEDs) in displays provides very high efficiency because the display does not absorb light using color filters and polarizers. As used herein, a uLED is a kind of LED having a diameter or cross-sectional area of less than 100 microns. The inorganic uLED display has a very high contrast since black pixels are set not to emit light. For inorganic uLED displays, blue gallium nitride (GaN) LEDs have an efficiency of 35-40% and reliability exceeds 50,000 hours, as established in general lighting. Sony has developed a passive matrix of uLEDs arranged in a display array using a pick and place system. However, because large displays require millions of LEDs, displays made with this process require more time and money than other technologies.

Moving microelectronic devices, optoelectronic devices, and subsystems with fluids of donor substrates / wafers to large area and / or irregular substrates provides new opportunities for extending the application of electronic and optoelectronic devices. For example, LED microstructures that display pixel sizes, such as bars, pins, or disks, are first fabricated on small wafers and then transferred to large area panel glass substrates, eliminating the need for backlighting. Can make

The possibility of misplaced or damaged LEDs occurs in any light emitting display manufacturing process. Given the fact that large displays can consist of millions of LEDs, detecting and replacing defective LEDs can be a wide range of tasks. For stamped transmission assemblies of arranged micro devices, one method (US Pat. No. 7723764) electrically tests a fully integrated array to identify a defective device and then cuts the drive lines of the defective device. And replace with a replacement device mounted on top of the defective device.

More generally, restoration steps are used to mitigate the negative effects of missing, misplaced, or failed devices by insulating the electrical contacts, covering the defects, and releasing the electrical contacts. U.S. Pat.No. 99252375 describes such defects by cutting of drive circuits as well as inspection and selective passivation of missing or defective array elements. Most are focused on producing flawless arrays. However, for arrays of millions of devices, a very low defect rate can make the product unusable.

Likewise, defects may occur when manufacturing large displays in a fluid assembly process. Therefore, it would be desirable to develop the ability to repair low rates of defects due to fluid self-assembly. More specifically, it would be advantageous if there was a systematic method for identifying the location of empty wells or broken light emitting devices and the location of subsequent corrections, and then selectively removing all remaining misaligned devices in the device area.

The present invention discloses a process in which a relatively small number of defects resulting from fluid self-assembly of a light emitting display can be systematically identified and repaired. Inspection of each alignment position is necessary to confirm the occupancy of the device intact and precisely directed. Inspection can be performed using microscopy and digital image processing methods (standard for industrial electronics manufacturing), but in one aspect, the light is induced in the assembled array, resulting in a totally intact and precisely positioned and aligned non-functional Identify additional devices. Misplaced or misdirected devices are also considered nonfunctional.

The output of the initial test test determines whether the valid device is occupied, invalid or damaged, or occupied. Through a restoration, the first step is to remove the invalid or damaged device from the alignment position. The second step in reconstruction is to fill the empty position with the effective element. The source of such devices may be the storage of new light emitting devices that are located in a misplaced device or vessel from the site (substrate surface) and sufficiently separated for individual adsorption by the adsorption and removal device. Both removal and replacement steps can be performed with a single device adsorption and removal subsystem. Alternatively, the replacement can be accomplished by one or more repeated fluid assembly steps.

The third step of restoration is to remove the remaining non-capturing elements. In fluid assembly, control of the accuracy of individual device trajectories is not always possible, and after assembly, misplaced devices may exist between the wells on the substrate surface. For low fill-factor arrays, the capture position represents a small percentage of the entire array area, and identifying the location of the misplaced individual elements is expensive and unnecessary. Rather, the misplaced device remaining in one large step can be eliminated, thus allowing the selection of the device in the wrong location on the device at the correct location in this step. The success of this restoration step is verified by a previous final inspection and further integrates the elements into the receiving substrate. If this test indicates that there is a persistent defect in the array, the restoration process is repeated accordingly.

Thus, a method for restoring a light emitting display is provided. The method provides a light emitting substrate comprising an array of positioned light emitting elements. After assembly, the light emitting substrate is inspected to determine the defective array position, and the defective item is removed from the light emitting substrate. In one aspect, the light emitting substrate comprises a well array and the light emitting element is arranged in the well but is not electrically connected to the light emitting substrate.

In another aspect, the light emitting element is a light emitting diode (LED). Subsequently, inspecting the light emitting substrate comprises irradiating the light emitting substrate with ultraviolet (UV) radiation, photoexciting the array of LEDs, and using an optically filtered test to validate the effective LED at the defective array location. Identifying with. The defective item may be identified as a missing light emitting device, a misaligned, misplaced or invalid light emitting device or debris (eg, a damaged light emitting device portion). After determining misaligned light emitting elements, misplaced light emitting elements, invalid light emitting elements or debris, a robotic adsorption and removal process is used to remove the defective item. The automated adsorption and removal process may use an electrostatic, mechanical or adhesive fixation mechanism as described in more detail below.

Placement of a replacement light emitting element within a defective array location can be accomplished using fluid assembly or reused adsorption and removal processes. After the replacement light emitting element is installed in any empty well, the light emitting substrate is re-inspected to determine the defective array position. If the retest passes, annealing is performed on the light emitting substrate so that the light emitting element is electrically connected to the light emitting substrate.

Further details of the light emitting substrate restoration process and the light emitting substrate restoration system are provided as follows.

1A-1C are schematic diagrams of a light emitting display restoration system.
2A and 2B are diagrams of an electrostatic adsorption and removal device.
3A-3F show one exemplary mechanical adsorption and removal apparatus.
4A-4C show an adhesive adsorption and removal device.
5A-5C illustrate an exemplary light emitting device replacement process.
6 is a high level restoration process flow diagram.
7A-7D are top views of exemplary light emitting substrates after one fluid assembly process.
8A and 8B are flowcharts illustrating a method of restoring a light emitting substrate.

1A-1C are schematic block diagrams of a light emitting display repair system. The light emitting display restoration system 100 includes an inspection subsystem 102, the inspection subsystem 102 inspecting the light emitting substrate 104, and the light emitting substrate 104 arranged in an array shape. Well 106. As shown, the light emitting device 108 is located within the well 106 but is not electrically connected to the light emitting substrate 104. Alternatively, although not shown, the light emitting device may be installed at a predetermined array position on the top surface of the planar light emitting substrate. Typically, the light emitting device 108 is deposited into the well 106 via a fluid assembly process, as disclosed in the related patent application described in the application to which this application claims priority. However, the wells may be filled using conventional automated pick-and-place devices. The action of the inspection subsystem is to identify the defective array location. The defective array location 110 (circled in dashed lines) is shown.

Preferably, the defective light emitting element 108 can be replaced more easily because the defective array location can be determined without electrical (eg, soldered) connection to the substrate. The luminescent display restoration system 100 includes a pick-and-remove subsystem 112, wherein the sorbent and removal subsystem 112 includes a defective item from the light emitting substrate 104. 113) is removed.

In one aspect, the light emitting element 108 is a light emitting diode (LED). In this case, the inspection subsystem 102 includes an illuminator 116, which illuminates the light emitting substrate 104 (or an individual LED 108). Light is irradiated and photoexciting is performed with respect to LED. Dual-mode image sensor 118 identifies the presence of LED 108 through visual contrast and edge detection in one mode, and wavelength-specific filtering in another mode. To effectively identify the LED 108 by detecting the desired photoluminescence excited by the light generating carrier.

As the UV emitting unit 116, a UV laser, UV LED, xenon arc lamp, mercury arc lamp or xenon mercury arc lamp can be used. When current leakage occurs in the LED 108, since recombination of excited electrons does not emit light, light emission due to the photoluminescence effect in the semiconductor layer is dominant. If the LED 108 is not defective, the photoluminescence effect occurs in both the active layer and the semiconductor layer. In this case, since light emission due to the photoluminescence effect in the active layer is dominant, the generated light has a color different from that of the defective LED. Thus, light having a predetermined wavelength is generated, and thus it is possible to determine whether the LED 108 is defective.

The image sensor 118 captures the wavelength of the light produced in the absence of defects, without defects, and without the LED 108, and compares the measurement results with a predetermined standard. In another aspect, inspection imaging can use spectroscopy instead of wavelength selective filters to more accurately quantify the photoluminescence of UV-excited LEDs. LED inspection may include a non-binary brightness assessment of uniformity criteria to determine the rejection threshold, and the LED inspection may be red-blue-green (RGB) color per pixel for subsequent calibration. You can check your balance.

The spectrometer collects all emitted light and records its distribution. Since this measurement typically does not include position data as is the case with charge-coupled devices (CCDs) or CMOS sensors, the position data must record the xy (horizontal) position of the test head. That is, only one LED can be inspected at a time. In contrast, a band gap filtered camera can examine a larger field of view (but with less quantification of wavelengths).

For gallium nitride (GaN) LEDs, the dominant wavelength is in the blue or green color spectrum, depending on the LED doping. For AlGaInP LEDs, the dominant wavelength is in the red spectrum. The filtered image sensor evaluates the wavelength by comparing the detected photoluminescence with a predetermined map cross reference location on the substrate. Defective array positions are determined by wavelengths of light that do not match the missing or expected color map. The inspection is performed before applying the color filter or color correction layer. Therefore, depending on the display design, the light emitting substrate 102 can be manufactured from one type (one color) of LEDs, two types (two colors) of LEDs, or three types (three colors) of LEDs. In one aspect, the image sensor may be replaced with a spectrometer which inevitably enables quantitative wavelength measurements through a smaller field of view. In another aspect, the filtered image sensor 118 compares the measured desired wavelength light intensity with a predetermined standard to determine if the LED is defective.

In summary, the inspection subsystem 102 determines which item is defective and identifies the missing light emitting device (well that is not filled by the light emitting device), misaligned light emitting device ("inverted" light emitting device). Filled wells), misplaced light emitting elements (wells not filled by LEDs), invalid light emitting elements and debris (e.g., damaged light emitting elements, debris from the manufacture of light emitting substrates, or solid objects in fluid assembly fluids) can do. In the case of misaligned light emitting elements, misplaced light emitting elements, or invalid light emitting elements and debris, the adsorption and removal system 112 may remove such defective items 113, as described in more detail below. Automatic adsorption and removal devices are used, and the use of automatic adsorption and removal devices employs fixing mechanisms such as static electricity, mechanical and adhesive. As will be understood in the art, adsorption and removal devices are systems for accurately measuring target locations (defective items) in relation to known optical / camera subsystems and / or known references such as substrate edges or corners. It includes.

2A and 2B show an electrostatic adsorption and removal device. The micro light emitting element is fixed to the transfer head by generating a static charge on the transfer head, which includes the separation and attraction of charge in the micro element. Removal is performed by releasing the charge separation of the head. The electrostatic adsorption and removal apparatus 200 includes a transfer head 202 capable of generating static electricity to adsorb the defective item 204 to the transfer head 202 (see FIG. 2A). Reference numeral 206 denotes the attraction by static electricity. The defective item 204 (see FIG. 2B) may be released when static electricity on the transfer head 202 dissipates. In one aspect, the transfer head is basically a capacitor that concentrates charge on the adsorption surface (protected by a thin dielectric). For example, the positive charge on the transfer head pulls electrons to the LED top surface, creating a small attraction. This process is effective because the light emitting element has a very small mass.

3A-3F show exemplary mechanical adsorption and removal devices. The transfer suction head may be a thin, heatable metal tip connected to the transfer head stage of stepper control xyz (movable in three dimensions). The tip is coated with a phase change material, approaching the substrate surface at the location of the defective item to be removed, and then the resistive heating of the tip to induce melting of the coating material, thereby causing the coating material to Contact with debris within or on the substrate top surface. The coating material then solidifies in cooling and removes loose material at this location when the tip is removed. The material and coating are removed in a bath or spray of solvent to dissolve the coating material, and the tip is immersed in a liquid bath of phase change polymer to recoat the new material. Alternatively, the transfer head 302 is disposable and may be discarded with the attached defective item 310. The greatest advantage of this method is that the z height (vertical) control near the defective array location can have a relatively low precision, such that the phase change material is contacted below gravity and is electrostatic or elastomeric adhesive method. In comparison, more particles of various particle sizes and shapes can be removed. Mechanical forces can be stronger than electrostatic forces or elastomeric adhesion.

Thus, the mechanical adsorption and removal device 300 includes a heat transfer head 302, which is coated with a liquid polymer coating layer 304. The heat transfer head 302 may be heated as shown by the voltage potential 306 (FIG. 3A) to convert the phase change polymer in the solid state to the liquid state 308 or to maintain the polymer in the liquid state. . After contacting the defective item 310 (FIG. 3B), the defective item is attached to the transfer head. As shown in FIGS. 3C and 3D, the transfer head 303 cools and converts the liquid polymer into a solid state 312 attached to the defective material 310. In FIG. 3E, the transfer head 302 removes the polymer using liquid 314 to remove the defective item, and in FIG. 3F, the transfer head 302 removes the polymer from the liquid polymer bath 316. 304).

4A-4C show an adhesive adsorption and removal device. In one aspect, the defective item and the transfer head are naturally bonded and have an overall bond strength proportional to the interface area. Release is achieved by deflection of the elastic surface which reduces the contact area of the hard defective device with the micro device, thereby reducing the holding force between the transfer head and the defective item. Adhesive adsorption and removal device 400 includes a transfer head 402 having a deformable contact surface area 404. The contact surface region 404 is adhesive, and the adhesion is realized by the adhesion of the main body of the contact surface region 404 or by the adhesive layer coated on the contact surface region 404 (see FIG. 4A). Since the transfer head 402 is not in direct contact with the surface of the light emitting substrate 104, the defective item 408 is attached in response to expanding (deforming) the contact surface area size, as shown in FIG. 4B. . Removal of the defective item is released by dipping the transfer head in a solvent or increasing the deformation of the transfer head to reduce the amount of surface area in contact with the defective item (not shown).

One variant of the adhesive method is to coat the transfer head with a liquid which is incidental to using a substrate that does not hold liquid after contact. One example is a polar liquid that holds a hydrophobic substrate surface and a defective item to be removed via surface tension after contact.

Returning to FIG. 1C, the restoration system 100 may further include a replacement subsystem. The empty wells 106 in the light emitting substrate may be filled through a fluid assembly process or may be filled with a reusable adsorption and removal system 120 as shown.

4A-4C can also be interpreted as removing a defective light emitting device from a substrate well using a deformable elastic transfer head. Restoration of the fluid assembled array can be reduced to two basic operations. Two basic operations are removing the light emitting device from the substrate and adding a replacement light emitting device to the light emitting substrate well. Removal of the broken or invalid element 408 from the well 106 requires the adsorption and removal transfer head 402 to overlap with the alignment location (eg, well) prior to close access and adsorption. For removal, the relative position of the transmission head 402 and the element portion 408 of the luminous means is not very important and can generally be achieved without feedback of the additional position in the form of a camera or a linear encoder.

After adsorption, the device is discarded out of the assembly zone and the transfer head is reset to adsorb and remove the next device. For light emitting devices that are recessed in the wells, the adhesive elastomer adsorption head may be deformed and in contact with the device. In the case of an electrostatic transfer head, an enhanced magnetic field may be needed to overcome the increased distance, and the square law has poor grip strength. Adsorption heads coated with phase change materials are also effective in removing broken devices and debris from the wells.

After the defective and broken device is removed from the well, the old location and the first empty area are subject to assembly of the new replacement device. This can be done through fluid assembly in a manner similar to the initial assembly, with the inspection / removal steps repeated until the array achieves the desired functional yield. Alternatively, the pick-and-remove xyz transfer head used for removal can be used to place the new device again. The additional process requires much higher precision in placement than removal, so the new head is taken from the stage area and passed through the bottom-up camera so that the transmission head modifies the relative position between the device center and the head center. In the case of radially asymmetrical elements, the angular direction may be modified at this point. The device is then placed in a substrate well and the device is deposited in a groove. In the case of electrostatic attachment, the deposition of the device can be achieved by blocking the electric field, but the inherent stiction of the micro-sized device may require mechanically assisted separation.

If the reliability of the adsorption and removal parallel movement is insufficient relative to the size of the array and the device, a transfer head, which can be deflected without damaging the conveyed device, is located near the alignment position and gently presses the device onto the assembly surface. Then, as shown in Figs. 5A to 5C, the transfer head moves the contacted element in the region of the groove so that the element is pressed into the groove and held mechanically. Due to the size and brittleness of the device, the downward force is carefully controlled and monitored by the piezoelectric force meter of the adsorption and removal head. In this way, assembly can still be achieved without complete knowledge and control of the relative positions of the adsorbed elements and wells.

The final reconstruction step is large area cleaning, which uses the differential force to remove off-place (misplaced) devices from the substrate. In this case, the well includes an alignment position, and the light emitting element or light emitting element in the field is located on the substrate surface and is not limited transversely by the well. As such, the adhesive surface in intimate contact with the substrate surface exerts a significantly stronger force on the device that is not in the correct position relative to the accurately positioned device in which it is recessed. This attraction can be realized by coulombic, dielectric electrophoretic or chemical adhesion. Another method takes advantage of the lateral retention of wells on correctly positioned devices and provides mechanical cutting forces on the substrate surface to remove misplaced devices. Cutting force may be provided by a direct force provided by a fluid or brush or solid surface flowing across the substrate. Inclined substrates and gravity may be used to guide the unassembled device out of the assembly area and to enter the collecting groove. In such a case, the substrate may be coupled to the directional vibration oscillator to reduce device stiction, and the substrate may be coated with a carrier fluid to assist in the movement of misaligned devices.

The method of final cleaning of non-fluid and specific gravity forces the surface of the substrate surface by removing the cylinder of the misplaced element, the rigid sheet corresponding to the assembled substrate dimensions, the flexible sheet or the brush with a critical dimension larger than the size of the element by translating the surface. When the cutting force is applied to the device, the correctly positioned device is not removed, and the incorrectly positioned device in the substrate is removed when the body is peeled off by removing a thin, flexible film such as polydimethylsiloxane (PDMS). Comes off together. In addition to the assembly retained by the elements in the recessed wells, this method is also applicable to alternative assemblies, where the device in the correct position is more firmly secured than the misplaced device, and the larger bond between the two adhesive forces. Add driving force. However, the misplaced device can be recovered in ink and recycled for future fluid assembly. After restoration, the substrate is inspected again and confirmed that no misplaced elements remain on the substrate due to damage of all alignment positions and the occupancy of valid elements.

5A-5C illustrate an exemplary light emitting device replacement process. The transmission head 500 is shown having a replacement light emitting element 502 attached thereto, and again deposits the light emitting element using any one of the above automatic adsorption and removal devices. The transfer head 500 secures the replacement light emitting element 502 to the top surface 504 of the light emitting substrate 104 at a location proximate to the well 106 being filled (see FIG. 5A). The transfer head 500 moves the replacement light emitting element 502 to the top surface 504 over the opening of the well 106, as indicated by arrow 506, to push the replacement light emitting element into the well (FIGS. 5B and 5C). Reference).

6 is a high level restoration process flow diagram. The system disclosed herein is well suited for processes that can be systematically identified and repaired when relatively few defects occur from fluid self-assembly. In step 602, a light emitting substrate is prepared, wherein the light emitting substrate includes a matrix of column and row wiring necessary for selectively operating individual light emitting elements, and also optionally includes an active matrix driving circuit, which is the priority of the present application. Is described in the related application claiming. Step 602 also includes forming a well on the top surface of the light emitting substrate. In step 604 the fluid assembly process secures the light emitting device in the light emitting substrate well. In step 606, an initial inspection is performed using the inspection subsystem described in FIG. 1. Inspection of each light emitting device is necessary to verify the occupancy of the device intact and intact. Inspection may be performed with digital image processing methods that are standard in the manufacture of microscopes and industrial electronics, but may also excite luminescence using UV light emission to further identify precisely located and aligned devices that are not intact but invalid. Correctly positioned but misaligned devices are also considered invalid.

In step 608 the defective array location is restored. The output of the initial inspection test (step 606) corresponds to a three-dimensional array of known alignment positions, and at the same time indicates whether the position has been occupied by an effective element, by an invalid element, and is not fragmented or occupied. Step 608a removes the invalid element or debris from the alignment position. Successfully performing this step effectively creates a two-dimensional well that describes the positions occupied or vacant in the effective device.

Step 608b fills the empty position with the effective element. The source of such devices may be the storage of new light emitting devices that are located in a misplaced device or vessel from the site (substrate surface) and sufficiently separated for individual adsorption by the adsorption and removal device. Thus, steps 608a and 608b can both realize the adsorption and removal operations of a single element. Alternatively, unoccupied wells may be filled using a second fluid assembly process.

In step 608c, the remaining misplaced light emitting element is removed. A misplaced light emitting element occupies the surface of the light emitting substrate outside of the wells on the surface of the substrate or outside the designated location. In fluid assembly (step 602), control of the accuracy for individual device trajectories is not always possible, and after assembly, misplaced devices may be present between the wells on the substrate surface. In the case of low charge factor arrays, the alignment position represents a small percentage of the total array area and is expensive and unnecessary to identify the position of the misplaced individual elements. Rather, because the misplaced device remaining in one large step can be eliminated, it is possible to select the device in the wrong place on the device at the correct location in this step. For example, a brush, wiper, gas or liquid can be applied to the top surface of the light emitting substrate. Alternatively, if step 608b uses a fluid assembly process, step 608b and step 608c may be combined.

The success of this reconstruction step is verified by a final inspection prior to step 610 and further integration of elements into the receiving substrate in a subsequent step 612. If this test indicates that there is a persistent defect in the array, the restoration process is repeated accordingly.

While the rest of the substrate can be inspected to assess the extent of the remaining light emitting devices, the easiest way to remove misplaced devices is for selective large scale operations. Otherwise, this process limits the initial inspection (step 606) to the well position and includes inspection of the entire substrate area in the final inspection (step 610) prior to integration. Therefore, two inspection methods, large area test and separate location test, are presented. If the fluid-assembled device is a micro-sized LED (uLED) with a diameter or cross section smaller than 100 microns, the optical excitation and wavelength selection measurements of the μLEDs may identify the presence of the μLEDs in the correct position. With sufficiently efficient optics, large area imaging can characterize the distribution of μLEDs on the assembly substrate. If separate inspection or imaging is lower than the entire area, the imaging system is arranged or transitioned over the assembly substrate surface, and the processed image data is occupied by valid, unoccupied, misplaced, invalid elements, or detects debris. It is used to generate one matrix corresponding to the substrate alignment position.

7A-7D are top views of exemplary light emitting substrates after a fluid assembly process. Integration is broken because it depends on the entire device for electrode contact, but the effective device is also removed. 7A shows the results of visual inspection. As shown, most of the wells 106 are occupied with light emitting elements 108, while some wells are empty. Assuming that the light emitting element is an LED, FIG. 7B shows the result obtained by exposing the light emitting substrate to UV light radiation. Some locations 300 marked "x" are occupied but do not feed back the expected intensity or wavelength, indicating that the LED occupying it is defective. FIG. 7C shows the well 302 in need of removing a defective LED and FIG. 7D shows the well 304 refilled with a replacement LED.

In one aspect, the restoration tool is a triaxial adsorption and removal head, and has a mode to recover from major defects in fluid assembly because of the ability to handle microelements, leaving missing elements, misaligned elements and remaining on the substrate surface. Restores misplaced devices, correctly positioned but broken devices. Industry standard pick and place operations are generally performed by air pressure-based holding forces between the head and the device, which requires that the vacuum port be smaller than the device processing surface. In the case of microdevices, the vacuum method is not suitable because the microscale port diameter creates significant air pressure resistance that limits gas flow and slows down operation. In addition, these small ports are likely to be clogged. At the micro scale, replacement treatment methods are preferred.

For use with the restoration system described herein, the contact surface of the adsorption and removal transfer head may be smaller than the minimum array pitch (between the wells) and larger than the light emitting element contact surface, thereby transferring a single micro device. As mentioned above, the method of holding the device in the major head may be electrostatic, mechanical or adhesive. Alternatively, the transfer head includes a vacuum-tensioned mechanical attachment through microelectromechanical system (MEMS) tweezers, topographically intrinsic features, or microporous features with holes significantly smaller than the device dimensions. For devices without symmetry, four-axis adsorption and removal transfer heads can be used.

8A and 8B are flowcharts illustrating a method of restoring a light emitting substrate. This method is depicted as a series of numbered steps for clarity, but numbering does not necessarily specify the order of the steps. It should be understood that some of these steps may be performed without the need to skip, perform in parallel, or maintain a strict order. In general, however, this method follows the numerical order of the steps indicated. This method starts from step 800.

Step 802 provides a light emitting substrate comprising an array of light emitting elements disposed thereon. Step 804 examines the light emitting substrate to detect defective array locations. Step 806 uses an adsorption and removal process to remove the defective item from the defective array location on the light emitting substrate. After filling the empty well with the replacement light emitting device in step 808, step 810 re-inspects the light emitting substrate to determine the defective array position, and after passing the re-inspection, step 812 anneals the light emitting substrate. In response to the annealing, step 814 electrically connects the light emitting device to the light emitting substrate.

In one aspect, step 802 provides a light emitting substrate having an array of wells, where the light emitting element is located in the well, but is not electrically connected to the light emitting substrate. If the light emitting device is an LED, inspecting the light emitting substrate in step 804 includes substeps. Step 804a irradiates the light emitting substrate with UV illumination. Step 804b performs optical excitation on the LED array, and step 804c identifies the defective array location by measuring the brightness of the LED at a predetermined wavelength. Defective items may include misaligned light emitting devices, misplaced light emitting devices, invalid light emitting devices, or debris. After identifying the defective item described above, step 806 removes the light emitting device from the defective array location using an automatic adsorption and removal process. The automatic adsorption and removal process used may use one of the retention mechanisms such as electrostatic, mechanical or adhesive.

In the case of the electrostatic mechanism, step 806a creates an electrostatic charge between the adsorption and removal transfer head and the defective item. Step 806b pulls the defective item to the transfer head in response to the electrostatic charge, and step 806c releases (dissipates) the electrostatic charge to release the defective item from the transfer head, or the step may include Discard the transfer head with the item.

In the case of a mechanical mechanism, step 806d coats the adsorption and removal transfer head with a liquid polymer. After contacting the defective light emitting element with the transfer head, step 806e cools the transfer head and step 806f converts the polymer to a solid state attached to the defective light emitting element. Step 806g cleans the transfer head to remove the defective light emitting element, and step 806h recoats the transfer head with a liquid polymer. Alternatively, step 806i discards the transfer head with the defective item attached.

In the case of the adhesive mechanism, step 806j provides a transfer head having a deformable contact surface area of adsorption and removal for the light emitting element, but which is adhesive to the defective light emitting element. Step 806k expands the deformable contact surface area of the transfer head to contact the defective light emitting element to respond to the contact, and step 806l attaches the defective light emitting element to the transfer head. More specifically, the deformable contact surface in step 806j may initially be a first flat surface area, and step 806k extends the deformable contact surface area of the transfer head to contact the defective light emitting element located in the well of the substrate. A second convex surface area is created. Step 806m discards the defective item.

In one aspect, the light emitting substrate comprises an array of wells filled with light emitting elements, and step 808 fills the empty wells using a repurposed automated adsorption and removal process as follows. Step 808a attaches the replacement light emitting element to the adsorption and removal transfer head. Step 808b places the replacement light emitting device on the top surface of the light emitting substrate at a location proximate the well to be filled. Step 808c moves the replacement light emitting device to the top surface. In response to the movement over the opening of the well of the replacement light emitting device, step 808d uses an elastic strain force to guide the replacement light emitting device into the well.

Systems and methods have been provided for the restoration of light emitting substrates. Examples of specific process steps and hardware units have been provided to illustrate the present invention. However, the present invention is not limited only to these examples. Those skilled in the art can devise other variations and embodiments of the present invention.

100,200,300,400 --- Luminous Display Restoration System
102 --- Inspection Subsystem
104 --- Light Emitting Board
Will --- Well
108,502 --- Light emitting element
110 --- Array Position
112 --- Adsorption and Removal Subsystem
113,204,310,408 --- Defective Item
206 --- Reference
308 --- liquid state
312 --- solid state
314 --- liquid
316 --- liquid polymer tub
120 --- reused adsorption and removal system
506 --- arrow
504 --- surface

Claims (25)

In a pick-and-remove method for restoring a light emitting display,
Providing a light emitting substrate comprising an array of positioned light emitting elements,
Inspecting the light emitting substrate to determine a defective array position, and
Removing the defective item from the defective array location using an adsorption and removal system in response to the inspection;
Providing the light emitting substrate includes a light emitting substrate having a well array, the light emitting element being located in the well, but not electrically connected to the light emitting substrate,
Using the adsorption and removal system comprises using a phase change retention mechanism,
Using the phase change maintenance mechanism,
Coating a pick-and-remove transfer head with a liquid polymer;
Contacting the defective item with the transfer head to allow the transfer head to cool;
Converting the polymer to a solid state and attaching to the defective item,
Coating the adsorption and removal transport head comprises coating one adsorption and removal transport head from a plurality of adsorption and removal transport heads,
The method,
After attaching the defective item, discarding it together with the transfer head, the adsorption and removal method for restoring a light emitting display.
delete The method of claim 1,
Examining the light emitting substrate to determine the defective array location includes determining a defective item, wherein the defective item is a missing light emitting device, a misaligned light emitting device, or a misplaced light. And a defective item selected from the group consisting of a light emitting element, an invalid light emitting element and a debris.
The method of claim 3, wherein
The step of using the adsorption and removal system may include removing misaligned light emitting devices, misplaced light emitting devices, invalid light emitting devices, and debris using the adsorption and removal system. Adsorption and removal methods for restoration.
delete delete delete delete The method of claim 1,
After removing the defective item, filling the empty well with a replacement light emitting device using a process selected from the group consisting of fluid assembly or reused adsorption and removal systems. Adsorption and removal method.
The method of claim 9,
After filling a replacement light emitting element in the empty well, re-inspecting the light emitting substrate to check a defective array position,
After retesting, annealing the light emitting substrate, and
And in response to the annealing, electrically connecting the light emitting element to the light emitting substrate.
The method of claim 1,
Providing the light emitting substrate includes providing a light emitting diode (LED) light emitting device,
Examining the light emitting substrate,
Irradiating the light emitting substrate by ultraviolet (UV) irradiation;
Photoexciting the array of LEDs, and
And determining the defective array position by measuring the brightness of the LED at a predetermined wavelength.
delete delete The method of claim 9,
Providing the light emitting substrate includes providing a light emitting substrate having an array of wells in which the light emitting elements are filled;
Filling an empty well with a replacement light emitting device using the reused adsorption and removal system,
Attaching the replacement light emitting element to the adsorption and removal transfer head,
Positioning a replacement light emitting device on the top surface of the light emitting substrate at a location proximate the filled well,
Moving the replacement light emitting device to an upper surface, and
In response to moving the replacement light emitting device over an opening in a well, guiding the replacement light emitting device into a well using an elastic strain force.
In a light emitting display restoration system,
The luminescent display restoration system includes an inspection subsystem and an adsorption and removal subsystem,
The inspection subsystem inspects a light emitting substrate comprising an array of wells, a light emitting element is disposed within the well, is not electrically connected to the light emitting substrate, and identifies a defective array position;
The adsorption and removal subsystem removes the defective item from the light emitting substrate,
The adsorption and removal subsystem uses a mechanical adsorption and removal device to remove defective items,
The mechanical adsorption and removal device,
A heat transfer head and a liquid polymer coating layer,
The liquid-state polymer coating layer coats the heat transfer head,
The heat transfer head cools after contacting the defective item and converts the liquid state polymer into a solid state to attach to the defective item,
And the heat transfer head is discarded together with the attached defective item.
The method of claim 15,
The light emitting device is a light emitting diode (LED),
Inspection subsystem includes illuminator and dual mode image sensor,
The illuminator irradiates ultraviolet (UV) spectral light onto the light emitting substrate and photoexcites the LED.
Wherein said dual mode image sensor performs visual contrast and edge detection in a first mode and performs wavelength specific filtering in a second mode to identify effective LEDs.
The method of claim 15,
And said inspection subsystem identifies a defective item selected from the group consisting of missing light emitting elements, misaligned light emitting elements, misplaced light emitting elements, invalid light emitting elements and debris.
delete delete delete delete delete delete delete The method of claim 15,
And a replacement subsystem to fill the empty wells with replacement light emitting elements, wherein the replacement subsystem uses a fluid assembly method or a reused adsorption and removal device.

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