Patent Application
20240405154
The present application claims the benefit of Chinese patent application No. 202310614589.3 filed on May 29, 2023, titled “Mass transfer method for LED lamp beads”, the entire contents of which are incorporated herein by reference.
The present application relates to semiconductor displays, and in particular, to a mass transfer method for LED lamp beads.
During the manufacturing of LED lamp beads, such as mini-LED/micro-LED, a series of processes are carried out to make LED lamp beads one by one on a growth substrate, and then LED lamp beads are transferred to a driver circuit substrate. Because the size of LED lamp beads is extremely small, the number of LED lamp beads that need to be transferred is extremely large. The technique of transferring a large number of micro-components from one substrate to another is known as mass transfer.
Due to the characteristics of mini-LED/micro-LED, the size of the LED lamp bead is very small. There remains a challenge of transferring and installing a large number of micron-sized LED lamp bead chip particles to the driver circuit substrate when using the mini-LED/micro-LED for display. This requires technical support with higher precision and higher transfer volume.
There are two difficulties in the mass transfer of LED lamp beads: first, the manufactured LED lamp beads are transferred from the growth substrate and to the driver board, and the transfer thickness of the manufactured LED lamp beads only accounts for about 3% of the overall thickness of the LED lamp beads and the growth substrate, so the fine operation technology required is difficult to operate; second, the quantities need to be transferred at one time is very large, for example, for a full high-definition display product (with a resolution of 1920*1080), there are 1920*1080*3=6,220,800 LED lamp beads to be transferred, so the efficiency of transferring millions of LED lamp beads is low.
The present application is to provide a mass transfer method for LED lamp beads, aiming to at least solve the technical problems of high difficulty and low efficiency in the existing mass transfer of LED lamp beads.
The present application provides a mass transfer method for LED lamp beads, the method includes:
In one of the embodiments, a first workbench includes a first operating platform and a first support column rotatably connected to the first operating platform, and the growth substrate is detachably fixed on one side of the first operating platform away from the first support column;
In one of the embodiments, a circular track groove is provided on one of the first operating platform and the first support column, and a sliding wheel is provided on the other one of the first operating platform and the first support column, the sliding wheel is slidably disposed in the circular track groove.
In one of the embodiments, the first workbench further includes a first air pipe and a first airbag, the first air pipe is fixedly installed on the first operating platform with an end of the first air pipe extending to protrude from the growth substrate, the first airbag is mounted at the end of the first air pipe and communicates with the first air pipe, the first airbag is pressed against the first substrate when inflated, so as to press and fix the growth substrate on the first operating platform.
In one of the embodiments, step S320 includes:
In one of the embodiments, each LED lamp bead has a first electrode facing away from the first substrate, a lamp mount in the lamp mount array is a lamp recess, and a second electrode is provided on a bottom of the recess.
In one of the embodiments, the first electrode includes a first anode and a first cathode, and the second electrode includes a second anode and a second cathode.
The first cathode is a first annular electrode, the first anode is a first solid block electrode, the first annular electrode is disposed around the first solid block electrode with a gap between the first annular electrode and the first solid block electrode. The second cathode is a second annular electrode, the second anode is a second solid block electrode, and the second annular electrode is disposed around the second solid block electrode with a gap between the second annular electrode and the second solid block electrode.
In one embodiment, a gap between the second annular electrode and a wall of the lamp recess is smaller than the gap between the first annular electrode and the first solid block electrode.
In one of the embodiments, after step S100, the method further includes: washing the growth substrate with a cleaning solution, so that a water film is formed on a surface of the LED lamp bead array;
and/or, after step S200, the method further includes: washing the driver circuit substrate with a cleaning solution, so that a water film is formed on a surface of the lamp mount array.
In one of the embodiments, step S400 is specifically:
The advantageous effect of the mass transfer method for LED lamp beads provided by the present application is: the LED lamp bead array including a plurality of LED lamp beads is transferred at one time through the growth substrate, in which the growth substrate is moved above the driver circuit substrate, and the growth substrate and/or driver circuit substrate is rotated, so that the LED lamp bead array is aligned with the lamp mount array, and then the release layer is evaporated so that the LED lamp bead array is separated from the first substrate, and the first substrate is removed. By aligning the LED lamp bead array with the lamp mount array, there is no need to transfer individual LED lamp beads with an extremely small thickness, which solves the technical problems of high difficulty and low efficiency in the existing mass transfer of LED lamp beads, thereby increasing the transfer amount of LED lamp beads, improving the alignment accuracy, and reducing the cost at the same time.
In order to more clearly illustrate the technical proposals in embodiments of the present application, accompanying drawings that are used in the description of the embodiments or exemplary existing technologies are briefly introduced hereinbelow. Apparently, the drawings in the following description are merely some embodiments of the present application. For those skilled in the art, other drawings can also be obtained according to these drawings without any creative effort.
The reference signs in the drawings are as follows:
Embodiments of the present application are described in detail below, examples of which are shown in the drawings. The same or similar reference numerals designate the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the drawings are exemplary and are intended to explain the present application and should not be construed as limiting the present application.
Reference throughout this specification to “one embodiment” or “an embodiment” means that a particular feature, structure or characteristic described in combination with the embodiment is included in at least one embodiment of the present application. Thus, the terms “in one embodiment” or “in some embodiments” appear in various places throughout the specification, not all referring to the same embodiments. Furthermore, the particular features, structures or characteristics may be combined in any suitable manner in one or more embodiments.
In the description of the present application, it should be understood that orientations or positional relationships indicated by terms “length”, “width”, “upper”, “lower”, “front”, “back”, “left”, “right”, “vertical”, “horizontal”, “top”, “bottom”, “inner”, “outer”, etc. are based on the orientations or positional relationships shown in the drawings, and are only for the convenience of describing the present application and simplifying the description, and are not for any indication or implication that the referred device or element must have a specific orientation, be constructed and operate in a specific orientation should not be construed as a limitation on the application.
In addition, the terms “first” and “second” are used for descriptive purposes only and cannot be understood as indicating or implying relative importance or implicitly indicating the quantity of indicated technical features. Therefore, features defined as “first” and “second” may explicitly or implicitly include one or more of these features.
In the present application, unless otherwise clearly specified and defined, terms such as “installation”, “connected”, “connection” and “fix” should be understood in a broad sense, for example, it can be a fixed connection or a detachable connection, or integrated; it can be mechanically connected or electrically connected; it can be directly connected or indirectly connected through an intermediary, and it can be the internal communication of two components or the interaction relationship between two components. Those of ordinary skill in the art can understand the specific meanings of the above terms in the present application according to specific situations.
The size of LED lamp beads, such as mini-LED and micro-LED, is small thus it is difficult to achieve mass transfer. Micro-LED (micro light-emitting diode) is a new generation of display technology. Compared with OLED (organic light-emitting display) technology, micro-LED has higher brightness and better luminous efficiency but lower power consumption, so the market prospect of micro-LED is very promising. The structure of micro-LED includes such as epi-up, flip-chip, and vertical structures. However, the size of each micro-LED is only 10 μm to 50 μm, which is exceptionally small, and the mass transfer thereof is more difficult.
There are two difficulties in the mass transfer of LED lamp beads: first, the manufactured LED lamp beads are transferred from the growth substrate and to the driver board, and the transfer thickness of the manufactured LED lamp beads only accounts for about 3% of the overall thickness of the LED lamp beads and the growth substrate, so the fine operation technology required is difficult to operate; second, the quantities need to be transferred at one time is very large, for example, for a full high-definition display product (with a resolution of 1920*1080), there are 1920*1080*3=6,220,800 LED lamp beads to be transferred, so it is necessary to consider that the transfer technology of millions of LED lamp beads must meet the existing efficiency requirements.
A related mass transfer method adopts the use of a combined transfer printing technology of mechanical press and laser welding. The LED lamp beads on the growth substrate are transferred to the driver circuit substrate by a transfer unit, and the LED lamp beads on the substrate are pressed down and fitted to the driver circuit substrate by a mechanical press so as to be welded to the driver substrate by a welding unit, and a monitoring unit monitors the effect, temperature, welding status, and the like. The current technical capability of mechanical transfer can transfer 50-100 LED lamp beads per second, the size of the lamp beads that can be transferred is 200 μm-50 μm, and the transfer accuracy reaches 2 μm-5 μm. Therefore, the mass transfer method in the related art has the following problems: first, the number of LED lamp beads transferred per second is small. Taking an efficiency of 100 LEDs per second as an example, for an FHD product, (1920*1080*3)/100/60/60≈17 hours. That is, it takes 17 hours to produce an FHD product, and it takes about 6 hours even with equipment with three presses, and the daily output is too low; second, the press unit needs to operate the LED lamp beads one by one, which causes wearing of the press and equipment damage; third, the structural design of the press is relatively sharp, which may cause damage to the LED bead.
The mass transfer method of LED lamp beads 121 in an embodiment of the present application will be described in conjunction with
S100: referring to
Specifically, the first substrate 11 is a sapphire substrate, a gallium nitride substrate, an aluminum nitride substrate, a silicon substrate, a gallium arsenide substrate, and a silicon carbide substrate, the present application does not limit the specific type of the first substrate 11. Optionally, the first substrate 11 is a wafer substrate, and the wafer substrate refers to a silicon wafer used for manufacturing silicon semiconductor circuits, and the raw material thereof is silicon. High-purity polycrystalline silicon is dissolved, and silicon crystal seeds are added and then slowly pulled out to form a cylindrical single-crystal silicon. The silicon ingot is ground, polished, and sliced to form a silicon wafer, that is, a wafer substrate.
Optionally, step S100 includes manufacturing the LED lamp bead array 12 on the first substrate 11. Specifically, a conventional LED chip is miniaturized, arrayed, and thinned utilizing the miniaturization process technology. For example, it undergoes processes like substrate, epitaxy process, epi-wafer, cleaning, evaporation, yellow light process, chemical etching, fusion, grinding, cutting, testing, and the like, the LED lamp beads 121 can be made into different shapes in the chemical etching stage. That is, the shape of the LED lamp beads 121, including the shape of the first electrode 1211, can be designed in the chemical etching stage.
S200: referring to
Specifically, the second substrate 21 is a sapphire substrate, a gallium nitride substrate, an aluminum nitride substrate, a silicon substrate, a gallium arsenide substrate, and a silicon carbide substrate, the present application does not limit the specific type of the second substrate 21.
The lamp mount array 22 is matched with the LED lamp bead array 12, including the situation that the LED lamp bead array 12 is designed and manufactured in accordance with the size, pitch, and arrangement of the lamp mount array 22, the situation that the lamp mount array 22 is designed and manufactured in accordance with the size, pitch, and arrangement of the LED lamp bead array 12, and the situation that the lamp mount array 22 and the LED lamp bead array 12 are designed and manufactured in accordance with a preset array, so as to match each other.
The present method may be performed by performing step S100 before step S200, or may be performed by performing step S200 before step S100, or may also be performed by simultaneously performing step S100 and step S200.
S300: referring to
S400: referring to
Optionally, after step S400, the method further includes: manufacturing a protective layer by physical deposition, and encapsulating the LED lamp bead array 12 on the driver circuit substrate 20.
In the present application, the LED lamp bead array 12 including a plurality of LED lamp beads 121 is transferred at one time through the growth substrate 10, and the growth substrate 10 is moved to a position above the driver circuit substrate 20. The LED lamp bead array 12 is aligned with the lamp mount array 22 by rotating the growth substrate 10 and/or the driver circuit substrate 20, and then the release layer 14 is evaporated to separate the LED lamp bead array 12 from the first substrate 11 so that the first substrate 11 is removed, and the LED lamp bead array 12 remains its alignment with the lamp mount array 22, thus there is no need to transfer individual LED lamp beads 121 which have a very small thickness and the technical problem of high difficulty and low efficiency in the existing mass transfer of the LED lamp beads 121 can be solved, thereby improving the transfer amount, the transfer efficiency and the alignment accuracy of the LED lamp beads 121 and reducing the cost at the same time.
When the LED lamp bead 121 is a micro-LED lamp bead 121, the micro-LED lamp bead 121 includes a red lamp bead, a blue lamp bead and a green lamp bead. In this case, in step 100, a first substrate, a second substrate and a third substrate are provided, the first substrate includes a red-light substrate and a red-light lamp bead array arranged on one surface of the red-light substrate, and the second substrate includes a blue-light substrate and a blue-light lamp bead array arranged on one surface of the blue-light substrate, the third substrate includes a green-light substrate and a green-light lamp bead array arranged on one surface of the green-light substrate. The red-light lamp bead array of the first substrate, the blue-light lamp bead array of the second substrate and the green-light lamp bead array of the third substrate are combined into the LED lamp bead array 12, which matches the lamp mount array 22 of the driver circuit substrate 20.
Step S300 and step S400 are respectively performed on the first substrate, the second substrate and the third substrate, without any specific limitations on the order of the substrates.
In a possible embodiment, step S300 and step S400 are first performed on the second substrate, that is, the second substrate is moved to a position above the driver circuit substrate 20, the second substrate and/or the driver circuit substrate 20 is rotated so that the blue-light lamp bead array is aligned with the lamp mount array 22; the release layer of the second substrate is evaporated to remove the blue-light substrate. Next, step S300 and step S400 are repeated on the first substrate, that is, the first substrate is moved to a position above the driver circuit substrate 20, and the first substrate and/or the driver circuit substrate 20 is rotated so that the red-light lamp bead array is aligned with the lamp mount array 22; the release layer of the first substrate is evaporated to remove the red-light substrate. Finally, step S300 and step S400 are repeated on the third substrate, that is, the third substrate is moved to a position above the driver circuit substrate 20, and the third substrate and/or the driver circuit substrate 20 is rotated so that the green-light lamp bead array is aligned with the lamp mount array 22; the release layer of the third substrate is evaporated to remove the green-light substrate.
In some embodiments, referring to
Step S300 specifically includes the following steps S310-S330:
S310: grasping the first workbench 30 by a robot arm, and moving the first workbench 30 to a position above the driver circuit substrate 20.
S320: rotating the first operating platform 31, that is, rotating the growth substrate 10, so that the LED lamp bead array 12 is aligned with the lamp mount array 22.
S330: separating the growth substrate 10 from the first operating platform 31.
In the present application, the growth substrate 10 can be conveniently moved and rotated by means of the first workbench 30 and the robot arm, so as to realize the alignment of the LED lamp bead array 12 and the lamp mount array 22.
Optionally, when the LED lamp bead 121 is a micro-LED lamp bead 121, the number of the first workbench 30 is three, the number of the robot arm is also three, and the three first workbenches 30 and the three robot arms respectively correspond to the first substrate, the second substrate and the third substrate, so that step S300 and step S400 are respectively performed on the first substrate, the second substrate and the third substrate in no particular order.
In one of the embodiments, referring to
In a possible example, referring to
In one possible example, referring to
Optionally, the first operating platform 31 is provided with a circular track groove 33, and the first support columns 32 are each provided with a sliding wheel 39.
In one of the embodiments, referring to
It can be understood that, in other embodiments, the growth substrate 10 may also be detachably fixed on the first operating platform 31 through a stretchable pressing block, or the growth substrate 10 may be detachably bonded to the first operating platform 31, which is not particularly limited here.
In one embodiment, the first support columns 32 are detachably connected to the first operating platform 31 through first suction cups 37, which is convenient for fixing and separating the first support columns 32 and the first operating platform 31, without the need for operations like removing screws and the like, which is conducive to improving efficiency.
In one embodiment, the growth substrate 10 may be processed and manufactured on the first workbench 30. Specifically, the first substrate 11 is detachably fixed on the first operating platform 31, and then the LED lamp bead array 12 is formed on the first substrate 11 through a manufacturing process.
In one of the embodiments, referring to
S321: placing the driver circuit substrate 20 on the second operating platform 41 of the second workbench 40, the first operating platform 31 is provided with a first optical alignment mark 38, and the second operating platform 41 is provided with a second optical alignment mark 48. The numbers of the first optical alignment mark 38 and the second optical alignment mark 48 are equal.
Optionally, the number of the first optical alignment mark 38 may be one or more. For example, referring to
Optionally, the number of the second optical alignment mark 48 may be one or more. For example, referring to
S322: rotating the first operating platform 31 to align the first optical alignment mark 38 with the second optical alignment mark 48. By means of the first optical alignment mark 38 and the second optical alignment mark 48, the alignment of the growth substrate 10 and the driver circuit substrate 20 can be conveniently determined and calibrated.
Specifically, referring to
Specifically, referring to
In some embodiments, referring to
In a possible example, the number of circular limiting groove 43 is one or more than two, and the more than two circular limiting grooves are arranged concentrically.
In one possible example, referring to
In one of the embodiments, referring to
It can be understood that, in other embodiments, the driver circuit substrate 20 may also be detachably fixed on the second operating platform 41 through a retractable pressing block, or the driver circuit substrate 20 may be detachably bonded to the second operating platform 41, which is not particularly limited here.
In one embodiment, the second support columns 42 are detachably connected to the second operating platform 41 through the second suction cups 47, facilitating fixing and separation between the second support columns 42 and the second operating platform 41, without the need for operations such as removing screws and the like, which is conducive to improving efficiency.
In some embodiments, referring to
In one embodiment, referring to
The shapes and dimensions of the first anode 1212, the first cathode 1213, the second anode 2222 and the second cathode 2223 are independently designed, and can be ring-shaped, dot-shaped, polygonal, circular, elliptical, or irregular.
In one embodiment, referring to
In another embodiment, referring to
Specifically, the gap X1 between the second annular electrode and the wall of the lamp recess 222 is smaller than the gap X2 between the first annular electrode and the first solid block electrode. With this design, even if the LED lamp bead 121 is displaced in the lamp recess 222, the displacement will not be greater than X1, otherwise, the second annular electrode will contact the wall of the lamp recess 222, restricting a further displacement of the LED lamp bead 121. The gap X2 is always greater than the gap X1, such that, even if the LED lamp bead 121 is displaced, the first anode 1212 of the LED lamp bead 121 will not contact the second cathode 2223 in the lamp recess 222 of the driver circuit substrate 20 to cause a short circuit.
In one embodiment, the driver circuit substrate 20 is designed to have a square shape, and the mounting position of the LED lamp bead 121 is etched out on the driver circuit substrate 20 through an etching process, and the size of the LED lamp bead is determined according to the resolution of the product. The lamp recess 222 is designed such that other positions except for the lamp recess 222 are designed to be flat.
In one embodiment, referring to
In one embodiment, referring to
In one embodiment, the lamp recess 222 is wider at the top and narrower at the bottom, so that the LED lamp bead 121 can be smoothly inserted into the lamp recess 222 during the transfer.
In some embodiments, after step S100, the method further includes: washing the growth substrate 10 with a cleaning solution, so that a water film is formed on the surface of the LED lamp bead array 12.
In some embodiments, after step S200, the method further includes: washing the driver circuit substrate 20 with a cleaning solution, so that a water film is formed on the surface of the lamp mount array 22.
In this way, since the growth substrate 10 and the driver circuit substrate 20 will inevitably contact with each other during the aligning process, and there will inevitably be friction therebetween when adjusting their positions, in order to avoid damage to the LED lamp bead 121 and the first electrode 1211 thereof, a cleaning solution is used. On the one hand, it can be ensured that there is no foreign matter in the joint portion of the growth substrate 10 and the driver circuit substrate 20, so that impurities that affect the quality can be avoided, and on the other hand, after cleaning, a layer of water film can be formed on the surfaces of the growth substrate 10 and the driver circuit substrate 20 facing each other, the water film can reduce friction and protect the LED lamp bead 121 from being damaged during alignment. After the alignment is completed, the driver circuit substrate 20 can be properly heated to evaporate the water film.
In some embodiments, referring to
S410: abutting bosses 51 of the roller 50 against a back surface of the growth substrate 10.
S420: heating the bosses 51 to evaporate the release layer 14.
It can be understood that, in other embodiments, the material of the release layer is a material that has a reduced or failed connecting ability upon irradiation by laser beams. For example, the first substrate 11 is a transparent substrate, and when the side of the first substrate 11 away from the LED lamp bead array 12 is irradiated by laser beams, the laser beams can pass through the first substrate 11 and reach the other side of the first substrate 11, so that the release layer is evaporated, and the LED lamp beads 121 are able to detach from the first substrate 11.
Specifically, the release layer is made of GaN, which can be partially decomposed to generate nitrogen gas when irradiated by laser beams, and the nitrogen gas generates thrust to push the LED lamp beads 121 away from the first substrate 11 and fall off from the first substrate 11.
In some other embodiments, the release layer is a photoresist, which can also achieve the separation.
The above descriptions are only preferred embodiments of the present application, and are not intended to limit the present application. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present application should fall within the scope of protection of the present application.
| Number | Date | Country | Kind |
|---|---|---|---|
| 202310614589.3 | May 2023 | CN | national |
