Patent Publication Number: US-2023163111-A1

Title: Led chip packaging module, fabrication method thereof, and display

Description:
CROSS-REFERENCE TO RELATED APPLICATIONS 
     This application is a continuation of International Application No. PCT/CN2021/096807, filed on May 28, 2021, which claims priority to Chinese Patent Application No. 202010736548.8, filed on Jul. 28, 2020. The disclosures of the aforementioned applications are hereby incorporated by reference in their entireties. 
    
    
     TECHNICAL FIELD 
     This disclosure relates to the field of semiconductor technologies, and in particular, to an LED chip packaging module, a fabrication method thereof, and a display. 
     BACKGROUND 
     A micro LED is also referred to as a micro light emitting diode, and is a self-light-emitting lighting device possibly applied to a next-generation display technology after a liquid crystal display (LCD) and an active-matrix organic light-emitting diode (AMOLED). 
     A core technology of a micro LED display is to combine millions to tens of millions of LED chips with sizes of tens of microns to form pixels of the display. Since an LED chip is a semiconductor device, structures such as metal electrodes on a surface of the LED chip may be processed in a semiconductor fabrication process. If the LED chip is to be sequentially arranged, according to design, on a drive backplane of a thin film transistor (TFT), a passive matrix (PM) line, or the like, mass transfer, micro bonding, and other processes are required. Different from conventional LED packaging processes in which only one single LED chip is transferred each time, in a mass transfer technology, a polydimethylsiloxane (PDMS) base material or another transfer head or stamp simultaneously transfers tens of thousands to hundreds of thousands of LED chips, to meet an output requirement for transferring more than a million LED chips in a short time period. 
     A size of a micro LED chip is only tens of microns. In a future objective for mass production, the size of the micro LED chip is expected to be reduced to 5 to 10 microns. Therefore, a size of a micro bump fabricated on the micro LED chip and a bonding process also needs to be reduced to less than 10 microns. In a conventional micro LED chip fabrication technology, bonding a micro LED chip and a drive backplane of a display is very difficult, and this adversely affects improvement of a production yield of display products. 
     SUMMARY 
     Embodiments of this disclosure provide an LED chip packaging module, a fabrication method thereof, and a display, to reduce bonding difficulty between a micro LED chip and a drive backplane of a display, and improve a yield of display products. 
     To achieve the foregoing objective, embodiments of this disclosure provide the following technical solutions. 
     According to a first aspect, an embodiment of this disclosure provides an LED chip packaging module, including: 
     a re-distribution layer RDL, where a plurality of first pads are disposed on a lower surface of the RDL; a micro light emitting diode micro LED chip disposed on an upper surface of the RDL, where an electrode of the micro LED chip faces the RDL and is connected to the RDL; and a micro integrated circuit micro IC disposed on the upper surface and/or the lower surface of the RDL, where an electrode of the micro IC faces the RDL and is connected to the RDL. The first pad is electrically connected to the micro IC by using the RDL. The micro IC is electrically connected to the micro LED chip by using the RDL. The first pad is configured to receive an external drive signal. The micro IC is configured to control, based on the external drive signal, a working state of the micro LED chip electrically connected to the micro IC. When the micro LED chip packaging module provided in this embodiment of this disclosure is driven by an external drive signal, the drive signal first controls the micro IC, and then the micro IC controls, based on the drive signal, a working state of at least one micro LED chip connected to the micro IC. In this way, a pad configured for connecting the electrode of the micro LED chip to external devices such as a drive backplane does not need to be disposed on the LED chip packaging module. This can reduce a quantity of pads between the micro LED chip packaging module and the external devices such as the drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     In an implementation, the micro LED chip forms a plurality of pixels, and each of the pixels includes at least one micro LED chip. Therefore, one or more micro LED chips may flexibly form pixels with different color capabilities, for example, full-color pixels and monochromatic pixels. 
     In an implementation, one micro IC is disposed corresponding to each of the pixels. The micro IC is disposed adjacent to the pixel corresponding to the micro IC. The micro IC is electrically connected, by using the RDL, to the micro LED chip in the pixel corresponding to the micro IC. In this way, each micro IC independently controls one pixel, forming a one-to-one control solution. 
     In an implementation, one micro IC is disposed corresponding to a plurality of pixels. The micro IC is disposed between the plurality of pixels corresponding to the micro IC. The micro IC is electrically connected, by using the RDL, to the micro LED chip in the plurality of pixels corresponding to the micro IC. In this way, each micro IC independently controls the plurality of pixels, forming a one-to-many control solution. This can reduce a quantity of micro ICs. 
     In an implementation, when the micro IC is located on the upper surface of the RDL, the electrode of the micro IC and the electrode of the micro LED chip are located in a same plane. This fabricates an RDL with a flat and smooth upper surface, to improve display performance of an LED chip packaging module. 
     In an implementation, the LED chip packaging module further includes a light isolation structure disposed on the upper surface of the RDL. The light isolation structure is distributed between adjacent pixels, and/or the light isolation structure is distributed between adjacent micro LED chips. The light isolation structure prevents light ray leakage from gaps between the pixels and the micro LED chips, reduces crosstalk between the pixels, increases or converges a visual angle of light emitting of the micro LED chip, improves light emitting efficiency, and improves display effect. 
     In an implementation, the LED chip packaging module further includes a transparent packaging layer disposed on the upper surface of the RDL. The transparent packaging layer covers a surface of the micro LED chip and/or the micro IC. The transparent packaging layer may fasten positions of the micro LED chip and/or the micro IC to each other and protect the micro LED chip and/or the micro IC. 
     In an implementation, the transparent packaging layer includes, on a side far away from the RDL, a packaging plane parallel to the upper surface of the RDL. A micro-nano structure is disposed on the packaging plane. The micro-nano structure improves light emitting efficiency of the micro LED chip, improves a light emitting field pattern, or improves another optical feature. 
     In an implementation, the LED chip packaging module further includes a color conversion material. Surfaces of some or all of the micro LED chips are coated with the color conversion material, to convert chromatic light emitted by the micro LED chips into another color. The color conversion material can enable a monochromatic micro LED chip to emit different chromatic light, reduce use of micro LED chips of different colors during fabrication of the LED chip packaging module, or implement light emitting correction on the LED chip packaging module in a later phase. 
     In an implementation, the pixel includes N primary micro LED chips and N secondary micro LED chips that are in a one-to-one correspondence with the N primary micro LED chips. The secondary micro LED chip is configured to take over the job of the corresponding primary micro LED chip when the corresponding primary micro LED chip fails, and N is a positive integer. In this way, when any primary micro LED chip fails, the micro IC may drive a secondary micro LED chip of a same color to take over the job of the failed micro LED chip, so that the pixel can still display a color normally, thereby maintaining display integrity of the LED chip packaging module and improving a yield of the LED chip packaging module. 
     In an implementation, the pixel includes N primary micro LED chips and a secondary micro LED chip. The secondary micro LED chip is configured to take over, when any one of the primary micro LED chips fails, the job of the failed primary micro LED chip, and N is a positive integer. In this way, when any primary micro LED chip fails, a transparent packaging layer around the secondary micro LED chip may be first removed by using a laser. Then, a color conversion material whose color is the same as that of the failed micro LED chip is sprayed, so that after being driven by the micro IC, the secondary micro LED chip can emit chromatic light whose color is the same as that of the failed micro LED chip. Therefore, the pixel can still normally display a color, and a quantity of secondary micro LED chips is reduced. 
     In an implementation, the pixel includes N primary micro LED chips. A secondary micro LED chip is further included between adjacent two pixels. The secondary micro LED chip is configured to take over, when any one of the primary micro LED chips in adjacent two pixels fails, the job of the failed primary micro LED chip, and N is a positive integer. In this way, when any primary micro LED chip fails, a transparent packaging layer around the secondary micro LED chip may be first removed by using a laser. Then, a color conversion material whose color is the same as that of the failed micro LED chip is sprayed, so that after being driven by the micro IC, the secondary micro LED chip can emit chromatic light whose color is the same as that of the failed micro LED chip. Therefore, the pixel can still normally display a color, and a quantity of secondary micro LED chips is reduced. 
     In an implementation, when a light ray emitted by the micro LED chip to an external environment does not pass through the RDL, an insulation flat layer of the RDL is a non-transparent material. In this way, the RDL can absorb or reflect the light ray emitted by the micro LED chip, to improve luminosity. 
     In an implementation, when a light ray emitted by the micro LED chip to an external environment passes through the RDL, an insulation flat layer of the RDL is a transparent material. In this way, the light ray emitted by the micro LED chip can efficiently pass through the RDL, to improve luminosity. 
     According to a second aspect, an embodiment of this disclosure provides another LED chip packaging module, including: 
     a re-distribution layer RDL, where a plurality of first pads are disposed on a lower surface of the RDL; and a micro light emitting diode micro LED chip disposed on an upper surface of the RDL, where an electrode of the micro LED chip faces the RDL and is connected to the RDL. The first pad is electrically connected to the micro LED chip by using the RDL. The first pad is configured to receive an external drive signal. The external drive signal is used to control a working state of the micro LED chip. When the micro LED chip packaging module provided in this embodiment of this disclosure is driven by an external drive signal, the drive signal is directly sent to at least one micro LED chip by using a pad and the RDL, so that one drive signal controls one or more micro LED chips. In this way, a pad configured for directly connecting the electrode of the micro LED chip to external devices such as a drive backplane does not need to be disposed on the LED chip packaging module. This can reduce a quantity of pads between the micro LED chip packaging module and the external devices such as the drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     In an implementation, the micro LED chip forms a plurality of pixels, and each of the pixels includes at least one micro LED chip. Therefore, one or more micro LED chips may flexibly form pixels with different color capabilities, for example, full-color pixels and monochromatic pixels. 
     In an implementation, each of the first pads is electrically connected to the micro LED chip of at least one of the pixels by using the RDL. In this way, the external drive signal may be sent to a micro LED chip in one or more pixels by using the first pad and the RDL, to control a display status of the one or more pixels. 
     In an implementation, the LED chip packaging module further includes a light isolation structure disposed on the upper surface of the RDL. The light isolation structure is distributed between adjacent pixels, and/or the light isolation structure is distributed between adjacent micro LED chips. The light isolation structure prevents light ray leakage from gaps between the pixels and the micro LED chips, reduces crosstalk between the pixels, increases or converges a visual angle of light emitting of the micro LED chip, improves light emitting efficiency, and improves display effect. 
     In an implementation, the LED chip packaging module further includes a transparent packaging layer disposed on the upper surface of the RDL. The transparent packaging layer covers a surface of the micro LED chip. The transparent packaging layer may fasten positions of the micro LED chip and/or the micro IC to each other and protect the micro LED chip and/or the micro IC. 
     In an implementation, the transparent packaging layer includes, on a side far away from the RDL, a packaging plane parallel to the upper surface of the RDL. A micro-nano structure is disposed on the packaging plane. The micro-nano structure improves light emitting efficiency of the micro LED chip, improves a light emitting field pattern, or improves another optical feature. 
     According to a third aspect, an embodiment of this disclosure provides an LED chip packaging method, including: 
     detachably disposing a micro LED chip and a micro IC on a first base plate, where an electrode of the micro LED chip and an electrode of the micro IC are disposed to face the first base plate; coating surfaces of the micro LED chip, the micro IC, and the first base plate with a transparent packaging layer; after the transparent packaging layer is cured, removing the first base plate, so that the transparent packaging layer forms a first plane that exposes the electrode of the micro LED chip and the electrode of the micro IC; fabricating an RDL on the first plane, where the micro IC is electrically connected to the micro LED chip by using the RDL; and fabricating a first pad on a lower surface that is of the RDL and that is away from the transparent packaging layer. The first pad is electrically connected to the micro IC by using the RDL. The first pad is configured to receive an external drive signal. The micro IC is configured to control, based on the external drive signal, a working state of the micro LED chip electrically connected to the micro IC. When the micro LED chip packaging module fabricated according to the method provided in this embodiment of this disclosure is driven by an external drive signal, the drive signal first controls the micro IC, and then the micro IC controls, based on the drive signal, a working state of at least one micro LED chip connected to the micro IC. In this way, a pad configured for connecting an electrode of the micro LED chip to external devices such as a drive backplane does not need to be disposed on the LED chip packaging module. This can reduce a quantity of pads between the micro LED chip packaging module and the external devices such as the drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     In an implementation, the detachably disposing a micro LED chip and a micro IC on a first base plate includes: disposing a plurality of micro LED chips on the first base plate to form a plurality of pixels. Each of the pixels includes at least one of the micro LED chips, and one micro IC is disposed adjacently on one side of each of the pixels. Therefore, one or more micro LED chips may flexibly form pixels with different color capabilities, for example, full-color pixels and monochromatic pixels. In addition, the pixels and micro ICs are configured in a one-to-one correspondence. 
     In an implementation, the RDL electrically connects the micro LED chip in each of the pixels to the micro IC adjacent to the micro LED chip. Therefore, each micro IC independently controls one pixel, forming a one-to-one control solution. 
     In an implementation, the detachably disposing a micro LED chip and a micro IC on a first base plate includes: disposing a plurality of micro LED chips on the first base plate to form a plurality of pixels, where each of the pixels includes at least one of the micro LED chips, and disposing at least one micro IC between a plurality of pixels. Therefore, one or more micro LED chips may flexibly form pixels with different color capabilities, for example, full-color pixels and monochromatic pixels. In addition, the pixels and micro ICs are configured in a one-to-many correspondence. 
     In an implementation, the RDL electrically connects each micro IC to the micro LED chip in at least one of the pixels. In this way, each micro IC independently controls the plurality of pixels, forming a one-to-many control solution. This can reduce a quantity of micro ICs. 
     In an implementation, before the coating surfaces of the micro LED chip, the micro IC, and the first base plate with a transparent packaging layer, the method further includes: fabricating a light isolation structure on the surface of the first base plate. The light isolation structure may be disposed between adjacent pixels, or may be disposed between adjacent micro LED chips. The light isolation structure prevents light ray leakage from gaps between the pixels and the micro LED chips, reduces crosstalk between the pixels, increases or converges a visual angle of light emitting of the micro LED chip, improves light emitting efficiency, and improves display effect. 
     In an implementation, before the coating surfaces of the micro LED chip, the micro IC, and the first base plate with a transparent packaging layer, the method further includes: coating surfaces of some or all of the micro LED chips with a color conversion material. The color conversion material is used to convert chromatic light emitted by the micro LED chips into another color. The color conversion material can enable a monochromatic micro LED chip to emit different chromatic light, reduce use of micro LED chips of different colors during fabrication of the LED chip packaging module, or implement light emitting correction on the LED chip packaging module in a later phase. 
     In an implementation, after the coating surfaces of the micro LED chip, the micro IC, and the first base plate with a transparent packaging layer, the method further includes: polishing a side that is of the transparent packaging layer and that is away from the first base plate, to form a packaging plane parallel to the first base plate; and fabricating a micro-nano structure on the packaging plane. The micro-nano structure improves light emitting efficiency of the micro LED chip, improves a light emitting field pattern, or improves another optical feature. 
     In an implementation, a first attachment layer is disposed on the surface of the first base plate, and the first attachment layer is configured to detachably dispose the micro LED chip and the micro IC. In this way, the micro LED chip and the micro IC may be temporarily fastened on the first base plate by using the first attachment layer. 
     In an implementation, before the detachably disposing a micro LED chip and a micro IC on a first base plate, the method further includes: growing a micro LED epitaxial wafer structure on a surface of a substrate; fabricating the epitaxial wafer structure into a plurality of micro LED chips in a standard semiconductor fabrication process; turning over the substrate and the micro LED chip on the substrate as a whole, and then detachably disposing the substrate and the micro LED chip on a second base plate; and removing the substrate. In this way, the plurality of micro LED chips that are disposed independently of each other may be obtained at a time. 
     In an implementation, a second attachment layer is disposed on a surface of the second base plate, and the second attachment layer is configured to detachably disposing the micro LED chip. In this way, the micro LED chip may be temporarily fastened on the second base plate by using the first attachment layer. 
     In an implementation, the detachably disposing a micro LED chip and a micro IC on a first base plate includes: attaching a plurality of micro LED chips from the second base plate at a time, disposing the plurality of attached micro LED chips on the first base plate, attaching, at a time, at least one micro IC from a third base plate on which the micro IC is detachably disposed, and disposing the attached micro IC on the first base plate. This implements mass transfer of the micro LED chip and the micro IC, and improves fabrication efficiency of the LED chip packaging module. 
     According to a fourth aspect, an embodiment of this disclosure provides another LED chip packaging method, including: 
     detachably disposing a micro LED chip on a first base plate, where an electrode of the micro LED chip is disposed to face the first base plate; coating surfaces of the micro LED chip and the first base plate with a transparent packaging layer; after the transparent packaging layer is cured, removing the first base plate, so that the transparent packaging layer forms a first plane that exposes the electrode of the micro LED chip; fabricating an RDL on the first plane, and mounting the micro IC on a lower surface that is of the RDL and that is away from the transparent packaging layer, where an electrode of the micro IC is disposed to face the RDL, and the micro IC is electrically connected to the micro LED chip by using the RDL; and fabricating a first pad on the lower surface of the RDL. The first pad is electrically connected to the micro IC by using the RDL. The first pad is configured to receive an external drive signal. The micro IC is configured to control, based on the external drive signal, a working state of the micro LED chip electrically connected to the micro IC. When the micro LED chip packaging module fabricated according to the method provided in this embodiment of this disclosure is driven by an external drive signal, the drive signal first controls the micro IC, and then the micro IC controls, based on the drive signal, a working state of at least one micro LED chip connected to the micro IC. In this way, a pad configured for connecting an electrode of the micro LED chip to external devices such as a drive backplane does not need to be disposed on the LED chip packaging module. This can reduce a quantity of pads between the micro LED chip packaging module and the external devices such as the drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     In an implementation, a plurality of micro LED chips are disposed on the first base plate to form a plurality of pixels, and each of the pixels includes at least one of the micro LED chips. Therefore, one or more micro LED chips may flexibly form pixels with different color capabilities, for example, full-color pixels and monochromatic pixels. 
     In an implementation, the RDL electrically connects each micro IC to the micro LED chip in at least one of the pixels. Therefore, each micro IC independently controls one pixel, forming a one-to-one control solution. Each micro IC independently controls the plurality of pixels, forming a one-to-many control solution. This can reduce a quantity of micro ICs. 
     In an implementation, the coating surfaces of the micro LED chip and the first base plate with a transparent packaging layer further includes: fabricating a light isolation structure on the surface of the first base plate. The light isolation structure may be disposed between adjacent pixels, or may be disposed between adjacent micro LED chips. The light isolation structure prevents light ray leakage from gaps between the pixels and the micro LED chips, reduces crosstalk between the pixels, increases or converges a visual angle of light emitting of the micro LED chip, improves light emitting efficiency, and improves display effect. 
     In an implementation, after the coating surfaces of the micro LED chip and the first base plate with a transparent packaging layer, the method further includes: polishing a side that is of the transparent packaging layer and that is away from the first base plate, to form a packaging plane parallel to the first base plate; and fabricating a micro-nano structure on the packaging plane. The micro-nano structure improves light emitting efficiency of the micro LED chip, improves a light emitting field pattern, or improves another optical feature. 
     According to a fifth aspect, an embodiment of this disclosure provides still another LED chip packaging method, including: 
     detachably disposing a micro LED chip on a first base plate, where an electrode of the micro LED chip is disposed to face the first base plate; coating surfaces of the micro LED chip and the first base plate with a transparent packaging layer; after the transparent packaging layer is cured, removing the first base plate, so that the transparent packaging layer forms a first plane that exposes the electrode of the micro LED chip; and fabricating an RDL on the first plane, and fabricating a first pad on a lower surface that is of the RDL and that is away from the transparent packaging layer. The first pad is electrically connected to the micro LED chip by using the RDL. The first pad is configured to receive an external drive signal. The external drive signal is used to control a working state of the micro LED chip electrically connected to the first pad. When the micro LED chip packaging module fabricated according to the method provided in this embodiment of this disclosure is driven by an external drive signal, the drive signal is directly sent to at least one micro LED chip by using a pad and the RDL, so that one drive signal controls one or more micro LED chips. In this way, a pad configured for directly connecting the electrode of the micro LED chip to external devices such as a drive backplane does not need to be disposed on the LED chip packaging module. This can reduce a quantity of pads between the micro LED chip packaging module and the external devices such as the drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     In an implementation, a plurality of micro LED chips are disposed on the first base plate to form a plurality of pixels, and each of the pixels includes at least one of the micro LED chips. Therefore, one or more micro LED chips may flexibly form pixels with different color capabilities, for example, full-color pixels and monochromatic pixels. 
     In an implementation, the coating surfaces of the micro LED chip and the first base plate with a transparent packaging layer further includes: fabricating a light isolation structure on the surface of the first base plate. The light isolation structure may be disposed between adjacent pixels, or may be disposed between adjacent micro LED chips. The light isolation structure prevents light ray leakage from gaps between the pixels and the micro LED chips, reduces crosstalk between the pixels, increases or converges a visual angle of light emitting of the micro LED chip, improves light emitting efficiency, and improves display effect. 
     In an implementation, after the coating surfaces of the micro LED chip and the first base plate with a transparent packaging layer, the method further includes: polishing a side that is of the transparent packaging layer and that is away from the first base plate, to form a packaging plane parallel to the first base plate; and fabricating a micro-nano structure on the packaging plane. The micro-nano structure improves light emitting efficiency of the micro LED chip, improves a light emitting field pattern, or improves another optical feature. 
     According to a sixth aspect, an embodiment of this disclosure provides a display, including: a drive backplane, a display driver integrated circuit DDIC configured to generate an external drive signal, and at least one LED chip packaging module according to any one of the first aspect, the second aspect, and the implementations of the first aspect and the second aspect. The DDIC and the at least one LED chip packaging module are disposed on the drive backplane. The drive backplane includes a second pad at a position corresponding to that of a first pad of the at least one LED chip packaging module. The second pad is connected to the DDIC by using a line. The first pad is configured for the LED chip packaging module to receive the external drive signal. The first pad is soldered to the second pad. The LED chip packaging module provided in embodiments of this disclosure has a smaller quantity of first pads, and a smaller quantity of second pads may be correspondingly disposed on the drive backplane. This reduces soldering difficulty between the LED chip packaging module and the drive backplane, and improves a display yield. 
     According to a seventh aspect, an embodiment of this disclosure provides an electronic device, including the display provided in the sixth aspect. 
    
    
     
       BRIEF DESCRIPTION OF DRAWINGS 
         FIG.  1    is a schematic flowchart of a current massive transfer and micro-nano bonding process of a micro LED; 
         FIG.  2    is a schematic diagram of a current inter-pixel optical structure; 
         FIG.  3    is a flowchart of an LED chip packaging method according to an embodiment of this disclosure; 
         FIG.  4    is a schematic diagram of a structure formed according to steps of an LED chip packaging method according to an embodiment of this disclosure; 
         FIG.  5    is a schematic diagram of a full-color pixel of a micro LED display; 
         FIG.  6    is a schematic diagram of an arrangement manner of a micro LED chip and a micro IC; 
         FIG.  7    is a schematic diagram of another arrangement manner of a micro LED chip and a micro IC; 
         FIG.  8    is a schematic diagram of fabricating a light isolation structure by using an LED chip packaging method according to an embodiment of this disclosure; 
         FIG.  9    is a schematic diagram of fabricating a color conversion material by using an LED chip packaging method according to an embodiment of this disclosure; 
         FIG.  10    is a schematic diagram of fabricating a light isolation structure and a color conversion material by using an LED chip packaging method according to an embodiment of this disclosure; 
         FIG.  11    is a schematic diagram of fabricating a micro-nano structure by using an LED chip packaging method according to an embodiment of this disclosure; 
         FIG.  12    is a schematic diagram of a structure of an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  13    is a schematic diagram of an arrangement manner of a micro LED chip and a micro IC in an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  14    is a schematic diagram of another arrangement manner of a micro LED chip and a micro IC in an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  15    is a schematic diagram of still another arrangement manner of a micro LED chip and a micro IC in an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  16    is a schematic diagram of another structure of an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  17    is a schematic diagram of an arrangement manner of primary and secondary micro LED chips in an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  18    is a schematic diagram of another arrangement manner of primary and secondary micro LED chips in an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  19    is a schematic diagram of still another arrangement manner of primary and secondary micro LED chips in an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  20    is a schematic diagram of yet another arrangement manner of primary and secondary micro LED chips in an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  21    is a flowchart of another LED chip packaging method according to an embodiment of this disclosure; 
         FIG.  22    is a schematic diagram of still another arrangement manner of a micro LED chip and a micro IC; 
         FIG.  23    is a schematic diagram of still another structure of an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  24    is a flowchart of still another LED chip packaging method according to an embodiment of this disclosure; 
         FIG.  25    is a schematic diagram of yet another structure of an LED chip packaging module according to an embodiment of this disclosure; 
         FIG.  26    is an example diagram of a pad and an RDL line of an LED chip packaging module; 
         FIG.  27    is a schematic diagram of a structure of a display according to an embodiment of this disclosure; and 
         FIG.  28    is a schematic diagram of splicing an LED chip packaging module of a display according to an embodiment of this disclosure. 
     
    
    
     DESCRIPTION OF EMBODIMENTS 
     To facilitate understanding of technical solutions in embodiments of this disclosure, before specific implementations of embodiments of this disclosure are described, some technical terms in the technical field to which embodiments of this disclosure belong are first briefly described. 
     Gallium nitride (GaN) is a compound of nitrogen and gallium. It is a binary III/V direct bandgap semiconductor commonly used in light-emitting diodes. 
     Metallic organic chemical vapor deposition (MOCVD) is a method for growing semiconductor thin films on base plates. The method may also be referred to as metal-organic vapor-phase epitaxy (MOVPE), organometallic vapor-phase epitaxy (OMVPE), and organometallic chemical vapor deposition (OMCVD). The “MO” or “OM” indicates that a precusor used in a growing process of a semiconductor thin film is a metal compound “metal-organic” or an organic metal compound. The following three letters “CVD” or “VPE” indicates that the grown semiconductor thin film is an amorphous thin film or a crystalline thin film. 
     A re-distribution layer (RDL) is a metal layer additionally disposed on a chip, so that an electrode or an input/output pad (I/O pad) of the chip can be re-disposed at another position of the chip, to connect to another integrated circuit or chip, or connect to an electrode or I/O pad of a different chip. 
     A display driver integrated circuit (DDIC) may generally include a microcontroller, a microprocessor, and an interface for a peripheral device, and is configured to generate a proper voltage, current, time sequence signal, or the like to drive pixels of a display, so that the display generates a corresponding image. 
     A surface-mount technology (SMT) is an electronic assembly technology. In this technology, electronic devices, such as resistors, capacitors, transistors, and integrated circuits, are mounted on a printed circuit board and form an electrical connection through brazing. Therefore, no through holes need to be reserved for pins of the devices. The used devices are also referred to as surface-mount devices (SMD). 
     Crosstalk, also referred to as crosstalk interference, indicates a coupling between two signal lines. A reason is that signal lines that are close to each other may interfere with each other due to undesired inductive and capacitive couplings. The capacitive coupling causes a coupling current, and the inductive coupling causes a coupling voltage. 
     Epitaxy, also referred to as epitaxial growth, is a technology used in a semiconductor device fabrication process to fabricate a new semiconductor layer by growing a new crystal on an original chip. A crystal or grain grown according to an epitaxy technology may also be referred to as an epitaxy, an epitaxial layer, or an epitaxial wafer. 
     A micro-nano structure is a functional structure that is manually designed, has a micron or nanoscale size, and is disposed in a specific manner. 
     A micro LED is also referred to as a micro light emitting diode, and is a self-light-emitting lighting device possibly applied to a next-generation display technology after a liquid crystal display (LCD) and an active-matrix organic light-emitting diode (AMOLED). A core technology of a micro LED display combines millions to tens of millions of LED chips with sizes of tens of microns to form pixels of the display. Therefore, a process of the micro LED display is greatly different from a process of combining an LED and a backlight layer by using a liquid crystal layer, and a vapor deposition process of an organic material for an AMOLED. 
     Since an LED chip is a semiconductor device, structures such as metal electrodes on a surface of the LED chip may be processed in a semiconductor fabrication process. If the LED chip is to be sequentially arranged, according to design, on a drive backplane of a thin film transistor (TFT), a passive matrix (PM) line, or the like, mass transfer, micro bonding, and other processes are required to transfer and fasten the LED chip on the drive backplane. Different from conventional LED packaging processes in which only one single LED chip is transferred each time, in a mass transfer technology, a polydimethylsiloxane (PDMS) base material or another transfer head or stamp simultaneously transfers tens of thousands to hundreds of thousands of LED chips, to meet an output requirement for transferring more than a million LED chips in a short time period. A size of a micro LED chip is only tens of microns. In a future objective for mass production, the size of the micro LED chip is expected to be reduced to 5 to 10 microns. Therefore, a size of a micro bump fabricated on the micro LED chip and a bonding process also needs to be reduced to less than 10 microns. In a conventional micro LED chip fabrication technology, it is difficult to meet such process requirement. 
     The following briefly describes a current mass transfer and micro-nano bonding process of a micro LED with reference to some accompanying drawings, so that a person skilled in the art can understand a technical scenario of embodiments of this disclosure and a disadvantage of the mass transfer and micro-nano bonding process during application of the micro LED. 
       FIG.  1    is a schematic flowchart of a current massive transfer and micro-nano bonding process of a micro LED. As shown in  FIG.  1   , a micro LED chip (for example, a blue or green micro LED chip) made of a GaN/InGaN material is used as an example. To obtain a structure of the micro LED chip, an LED epitaxial wafer structure (LED epi-layer)  020  may be first grown on a surface of a substrate  010  made of a sapphire sub material. Then, the epitaxial wafer structure  020  is fabricated into a large number of micro LED chips  030  with sizes of about 10 microns in a standard semiconductor fabrication process. In addition to an ohmic electrode  040  (the ohmic electrode  040  includes a P/N electrode of the LED chip) fabricated to reduce a current flowing into a semiconductor, a micro bump  050  prepared for a subsequent bonding process needs to be fabricated on a surface of the micro LED chip  030 . The micro bump  050  is prepared on the ohmic electrode  040 . To reduce a temperature required by the bonding process, the micro bump may be made of a low-temperature bonding metal alloy including indium In, tin Sn, and copper Au. After a chip fabrication process is completed, the substrate  010  and the epitaxial wafer structure  020  on the substrate  010  may be turned over and attached to a base plate  1 . The base plate carrier  1  may be made of a material such as glass, and a surface of the base plate carrier  1  has an attachment layer  061 . The attachment layer  061  is in contact with the micro bump  050 , to temporarily fasten the epitaxial wafer structure  020  without damaging a device structure. Next, to remove the sapphire substrate  010 , a laser may be used to irradiate the epitaxial wafer structure  020  from the sapphire substrate  010 . A wavelength of the laser is not absorbed by the sapphire substrate  010 , but reacts with the GaN material. In this way, the epitaxial wafer structure  020  is separated from the sapphire substrate  010 . 
     After the epitaxial wafer structure  020  is separated from the sapphire substrate  010 , the micro LED chip  030  is separately attached to the base plate carrier  1 . In this case, a required micro LED chip  030  may be selectively attached or absorbed from the base plate carrier  1  by using a patterned transfer head (stamp). The stamp may be made by using a van der Waals force (van der waals force) PDMS material. Alternatively, the micro LED chip  030  may be absorbed by using other mechanisms such as electrostatic force and magnetic force. After the micro LED chip  030  is attached by using the stamp, the micro LED chip  030  may be transferred to another base plate carrier  2 . A surface of the base plate carrier  2  also has an attachment layer  062  or an attachment apparatus, to temporarily fasten the micro LED chip  030 . Generally, to enable the PDMS stamp to smoothly attach the micro LED chip  030  from the base plate carrier  1  and to smoothly and temporarily fasten the micro LED chip  030  on the base plate carrier  2 , the attachment force should meet: attachment layer  061 &lt;PDMS&lt;attachment layer  062 . Therefore, the attachment layer  061  and the attachment layer  062  may be made of different materials. Transferring the micro LED chip  030  from the base plate carrier  1  to the base plate carrier  2  by using the stamp has the following objectives, including: adjusting a spacing between the micro LED chips  030 , making the micro LED chips  030  form a full-color arrangement (for example, a red, green, and blue RGB arrangement) on the surface of the base plate carrier  2 , or performing a double-sided fabrication process of another chip. 
     After the micro LED chips  030  are arranged on the surface of the base plate carrier  2 , all the micro LED chips  030  may be attached at a time by using another stamp and transferred to a corresponding area of a drive backplane  070 . Then, the micro bump  050  is used to enable positive and negative electrodes of the surface of the micro LED chip  030  to be mechanically and electrically connected to corresponding electrodes  080  on the drive backplane. The following process procedure is generally used herein: The positive and negative electrodes of the surface of the micro LED chip  030  are aligned with the corresponding electrodes  080  on the drive backplane. The micro LED chip  030  is pressed and heated to soften a solder material of the micro bump  050 , so that the positive and negative electrodes of the surface of the micro LED chip  030  are connected to and share metal with the corresponding electrodes  080  on the drive backplane, and the temperature is reduced. 
     It may be understood that the micro bump and bonding process shown in  FIG.  1    can implement an electrical connection between the positive and negative electrodes on the surface of the micro LED chip and the corresponding electrodes on the drive backplane. However, the size of the micro LED chip is increasingly miniaturized. When the size of the micro LED chip is reduced to an extent, for example, 10 to 15 microns or less, the micro bump and bonding process shown in  FIG.  1    is difficult to overcome problems in process implementation and a production yield. Details are as follows: 
     1. The micro bump generally includes solder materials such as indium In or tin Sn, which reduces a bonding temperature. However, these materials are also prone to diffuse in an alloy. To prevent the solder material from diffusing to an ohmic metal layer, which affects a device feature and a yield, a gold Au or another metal layer in the micro bump usually needs to be thickened, which is not conducive to miniaturization of the micro LED chip. In addition, when the micro LED chip is connected to the drive backplane in the bonding process, the chip and the drive backplane are mechanically and electrically connected by using the micro bump. Changes in parameters such as a contact status between the stamp and the chip, pressure and temperature evenness, and cooling in the bonding process may cause changes in a distance, an angle, and a direction between the chip and the backplane. As a result, a field pattern of each micro LED chip is slightly different. A user may perceive pixel disorder when viewing the display. 
     2. The micro LED chip cannot be detected before all processes are completed. The micro LED chip can be powered on and a feature analysis and test can be performed only after the micro LED chip is connected to the drive backplane. Therefore, after all the processes shown in  FIG.  1    are completed, if the test shows that the micro LED chip fails due to the micro LED chip itself or a process problem, a non-defective micro LED display can be obtained only after a repair process. However, the repair process relates to removal of the failed micro LED chip, pad cleaning, resetting, transfer and bonding of a single micro LED chip, and other processes. It is difficult to implement the repair process in technology and in a production environment, and each pixel takes unit labor hours far greater than labor hours for mass transfer. In addition, to avoid the repair process, a possible manner is to provide a secondary chip (redundancy). In short, in a redundancy manner, a quantity of secondary micro LED chips is doubled on the micro LED display. When an original micro LED chip fails and cannot operate, a secondary chip takes over the job of the original micro LED chip to maintain complete full-screen light emitting. It is clear that this manner increases production costs of the display and reduces resolution of the display. 
     3. An optical process between micro LED chips or a volumization process of another device is difficult. As shown in  FIG.  2   , in addition to a thickness of a micro LED chip, a thickness of a micro bump needs to be added to each pixel on the micro LED display to form a total thickness of the pixel. Generally, to improve a fault tolerance and a yield of bonding, the thickness H 1  of the micro bump may reach 5 to 8 microns. If the thickness of the micro LED chip is added, a total thickness H 2  of each pixel may reach 10 to 15 microns or even higher. In this case, a depth-to-width ratio of the total thickness H 2  of the pixel to a distance B 1  between pixels is high. For example, if an optical structure  090  that changes a light type or reduces crosstalk is fabricated between the pixels, the excessively high depth-to-width ratio may cause a decrease in precision and a yield of a semiconductor process such as inter-pixel photoetching, and may also adversely affect a volumization objective of another sensing device. 
     To resolve the foregoing technical problem, an embodiment of this disclosure provides an LED chip packaging method. The method may be applied to the field of packaging various LED chips. For example, a micro LED chip or a mini LED chip is packaged on a base plate such as a TFT, to fabricate a micro LED or a mini LED chip packaging module, a display, or the like. 
     The following describes in detail the method provided in this embodiment of this disclosure by using an example in which a micro LED chip is packaged to fabricate a micro LED chip packaging module. It may be understood that the following method steps are also applicable to a packaging process of a mini LED chip or another LED chip. 
       FIG.  3    and  FIG.  4    are respectively a flowchart and a schematic diagram of a structure formed according to steps of an LED chip packaging method according to an embodiment of this disclosure. 
     As shown in  FIG.  3    and  FIG.  4   , the method may include the following steps. 
     Step S 101 : Grow a micro LED epitaxial wafer structure  120  on a surface of a substrate  110 . 
     A material that can be used as the substrate  110  of the epitaxial wafer structure  120  may include, for example, sapphire, aluminum nitride AlN, silicon carbide SiC, a GaN single crystal material, and another material. This is not limited in this disclosure. 
     In a specific implementation, an epitaxial material used to grow the epitaxial wafer structure  120  may be determined based on a color of light emitted by a micro LED chip prepared as required. For example, if a micro LED chip emitting blue chromatic light or green chromatic light needs to be prepared, a GaN/InGaN material may be used to grow the epitaxial wafer structure  120 . For another example, if a micro LED chip emitting red chromatic light needs to be prepared, a material such as GaAsP may be used to grow the epitaxial wafer structure  120 . Other materials that can be used to grow the epitaxial wafer structure  120  may further include SiC, AlGaP, and the like. Due to a limited length of this specification, details are not further described herein. 
     It should be additionally noted herein that, as shown in  FIG.  5   , in a micro LED display  100 , each full-color pixel may include a plurality of micro LED chips. In an example of a most basic pixel structure, the pixel structure may include a micro LED chip R whose epitaxial material emits red chromatic light, a micro LED chip G whose epitaxial material emits green chromatic light, and a micro LED chip B whose epitaxial material emits blue chromatic light. Therefore, to obtain a micro LED chip required by the full-color pixel, different epitaxial wafer structures  120  that can emit different chromatic light may need to be grown on different substrates  110  by using different epitaxial materials during actual production. For example, GaN/InGaN is used on a substrate  110  to grow an epitaxial wafer structure  120  that can emit blue chromatic light, and GaN/InGaN is used on another substrate  110  to grow an epitaxial wafer structure  120  that can emit green chromatic light. 
     Step S 102 : Fabricate the epitaxial wafer structure into a plurality of micro LED chips in a standard semiconductor fabrication process. 
     In a specific implementation, an extra part of the epitaxial wafer structure  120  may be removed by using etching or another material removal technology. A remaining epitaxial wafer structure  120  forms a plurality of independent structures that have sizes of about 10 microns and are disposed at a spacing of on the substrate  110 . Then, an ohmic electrode (referred to as electrode)  140  that can reduce a current flowing into a semiconductor is fabricated on a side that is of each independent structure and that is away from the substrate. In this way, a complete micro LED chip  130  can be formed, and each independent structure finally forms a micro LED chip  130 . 
     Compared with the micro LED chip packaging structure using the micro bump and a soldering process shown in  FIG.  1   , no micro bumps need to be fabricated for the micro LED chip  130  fabricated in this embodiment of this disclosure except that the electrode  140  is included. This reduces a height of the micro LED chip. 
     It should be additionally noted that the foregoing size “10 microns” is merely an example size, and does not constitute a specific limitation on the size of the micro LED chip. Generally, the size of the micro LED chip may reach 1 μm to 60 μm. A person skilled in the art may determine a corresponding semiconductor fabrication process based on a common size range of the micro LED chip. This is not limited in this disclosure. 
     Step S 103 : Turn over the substrate  110  and the micro LED chips  130  on the substrate as a whole, and then detachably dispose the substrate and the micro LED chips on a second base plate  150 . 
     The second base plate  150  may be made of a material such as glass or a silicon wafer, and a second attachment layer  160  is disposed on a surface of the second base plate  150 . After the substrate  110  and the micro LED chips  130  on the substrate  110  are turned over as a whole, the substrate  110  and the micro LED chips  130  on the substrate  110  may be moved to the second base plate  150 . In this way, the second attachment layer  160  faces one end that is of the micro LED chip  130  and that has an electrode  140 . Next, the substrate  110  and the micro LED chip  130  on the substrate  110  are moved downward. In this way, the electrode  140  of the micro LED chip  130  is in contact with the second attachment layer  160  and is attached to the second base plate  150 . The second attachment layer  160  does not fasten the micro LED chip  130  and the second base plate  150  for a long time, and only temporarily and detachably fasten the micro LED chip  130  without damaging a device structure of the micro LED chip  130 . In this way, the micro LED chip  130  can be separated from the second base plate  150  when necessary. 
     Step S 104 : Remove the substrate. 
     In a specific implementation, a laser may be used to irradiate the epitaxial wafer structure of the micro LED chip  130  from the substrate  110 . A wavelength of the laser enables the laser to pass through the substrate  110  without being absorbed by the substrate  110 . The laser reacts with the GaN material of the epitaxial wafer structure, so that the epitaxial wafer structure of the micro LED chip  130  is separated from the substrate  110 , thereby removing the substrate  110 . 
     In addition, a person skilled in the art may also separate the substrate  110  from the micro LED chip  130  by using another semiconductor fabrication process. This is not limited in this disclosure. 
     Step S 105 : Detachably dispose the micro LED chips  130  and a micro IC  180  on a first base plate  170 . The electrode  140  of the micro LED chip  130  and an electrode  230  of the micro IC  180  are disposed to face the first base plate  170 . 
     In an embodiment, a plurality of micro LED chips  130  and the micro IC  180  may be disposed on the first base plate  170  to form a plurality of pixels. Each of the pixels includes at least one of the micro LED chips  130  and one micro IC  180 . 
     For example, as shown in an arrangement a in  FIG.  6   , a pixel includes a micro LED chip B emitting blue chromatic light, a micro LED chip G emitting green chromatic light, and a micro LED chip R emitting red chromatic light. The three micro LED chips are arranged in parallel in a row to form a standard RGB arrangement. Each pixel includes a micro IC  180 , and the micro IC  180  and the micro LED chip are arranged in parallel in a same row. 
     For example, as shown in an arrangement b in  FIG.  6   , a pixel includes a micro LED chip B emitting blue chromatic light, a micro LED chip G emitting green chromatic light, and a micro LED chip R emitting red chromatic light. The three micro LED chips are arranged in parallel in a row to form a standard RGB arrangement. Each pixel includes one micro IC  180 , and the micro IC  180  is disposed above or below the three micro LED chips. 
     For example, as shown in an arrangement c in  FIG.  6   , a pixel may include four micro LED chips, for example, two micro LED chips B emitting blue chromatic light, one micro LED chip R emitting red chromatic light, and one micro LED chip G emitting green chromatic light. The four micro LED chips are arranged in a rectangular manner. A position of each micro LED chip may be considered as a corner of a rectangle. The two micro LED chips B emitting blue chromatic light are disposed in a diagonal manner. Each pixel includes one micro IC  180 . The micro IC  180  may be disposed on one side of four micro LED chips. 
     In another embodiment, a plurality of micro LED chips  130  may be arranged into a plurality of pixels on the first base plate  170 . Each pixel includes at least one micro LED chip  130 . In addition, at least one micro IC  180  is distributed between these pixels. 
     For example, as shown in an arrangement d in  FIG.  7   , a pixel includes a micro LED chip B emitting blue chromatic light, a micro LED chip G emitting green chromatic light, and a micro LED chip R emitting red chromatic light. The three micro LED chips are arranged in parallel in a row to form a standard RGB arrangement. In each row or column of pixels, one micro IC  180  is disposed for every N (N is a positive integer greater than 1) pixels. Each micro IC  180  may control N pixels. 
     For example, as shown in an arrangement e in  FIG.  7   , a pixel includes a micro LED chip B emitting blue chromatic light, a micro LED chip G emitting green chromatic light, and a micro LED chip R emitting red chromatic light. The three micro LED chips are arranged in parallel in a row to form a standard RGB arrangement. In pixels in each square area, one micro IC  180  is disposed for every N (N is a positive integer greater than 1) pixels. Each micro IC  180  may control N pixels in the area. 
     To implement the foregoing arrangement manner, a plurality of second base plates  150  may be prepared in advance. A micro LED chip  130  emitting one type of chromatic light may be detachably disposed on each second base plate  150 . Then, in step S 105 , the micro LED chips  130  emitting different chromatic light may be respectively absorbed from different second base plates  150  and disposed on the first base plate  170 . At least one micro IC  180  may be absorbed at a time from a third base plate on which the micro IC  180  is disposed and disposed on the first base plate  170 . An attachment layer is also disposed on the third base plate, to detachably dispose the micro IC  180 . The foregoing actions of absorbing and disposing the micro LED chip  130  and the micro IC  180  may be repeated for one or more times. One or more chips may be absorbed each time, so that the plurality of micro LED chips and the at least one micro IC  180  finally form a preset pixel arrangement on the first base plate  170 . 
     The first base plate  170  may be made of a material such as glass or a silicon wafer. A first attachment layer  190  is disposed on a surface of the first base plate  170 . This can detachably and temporarily fasten the micro LED chip  130  and the micro IC  180  without damaging device structures of the micro LED chip  130  and the micro IC  180 . When the micro LED chip and the micro IC  180  are detachably disposed on the first base plate  170 , ends of electrodes of the micro LED chip  130  and the micro IC  180  both are in contact with the first attachment layer  190  of the first base plate  170 . 
     Step S 106 : Coat surfaces of the micro LED chips  130 , the micro IC  180 , and the first base plate  170  with a transparent packaging layer  210 . 
     The transparent packaging layer  210  may include, for example, an epoxy resin material and a silicone resin material. The transparent packaging layer  210  needs to be cured for a period of time after coating. After curing, relative positions of the micro LED chip  130  and the micro IC  180  can be fastened. In a preferred manner, a coating height of the transparent packaging layer  210  on the surface of the first base plate  170  may be higher than a total height of the micro LED chip  130  and the micro IC  180 . In this way, after the transparent packaging layer  210  is cured, the transparent packaging layer  210  may be polished or ground, to form a packaging plane  240  that is parallel to the first base plate  170  and that has good flatness. 
     Step S 107 : After the transparent packaging layer  210  is cured, remove the first base plate  170 , so that the transparent packaging layer  210  forms a first plane  250  that exposes the electrode  140  of the micro LED chip  130  and the electrode  230  of the micro IC  180 . 
     Because the ends of the electrodes of the micro LED chip  130  and the micro IC  180  are in contact with the first attachment layer  190  of the first base plate  170 , after the micro LED chip  130  and the micro IC  180  are separated from the first base plate  170 , the electrodes of the micro LED chip  130  and the micro IC  180  are exposed from the first plane  250  of the transparent packaging layer  210 . 
     Step S 108 : Fabricate an RDL  220  on the first plane  250 . 
     The RDL  220  includes an insulation flat layer and a plurality of RDL lines distributed at the insulation flat layer. The insulation flat layer may be made of silicon or a polymeric material. The RDL line may be made of a conductive material such as copper by using a semiconductor fabrication process technology such as photoetching, vapor deposition, or electroplating. The RDL line may be a single-layer line or a multi-layer line. This is not limited in embodiments of this disclosure. 
     The RDL line may be divided into two parts according to different directions of the RDL line. A first part of the RDL line is connected to the electrode  140  of the micro LED chip  130  and the electrode  230  of the micro IC  180 , so that each micro IC  180  is electrically connected to at least one micro LED chip  130  by using the RDL  220 . One end of a second part of the RDL line is connected to the electrode  230  of the micro IC  180 , and the other end is exposed on a lower surface  260  of the RDL  220 . In this way, if an external drive signal is introduced into the other end of the second part of the RDL line, the drive signal may be transmitted to the micro IC  180 . 
     Step S 109 : Fabricate a pad  270  and a bump  330  on the lower surface  260  of the RDL  220 . 
     The pad  270  is connected to the other end of the second part of the RDL line. Therefore, the pad  270  can be electrically connected to the micro IC  180  by using the RDL  220 . The bump (bump)  330  is fabricated on the pad  270 , so that the pad  270  is connected to an external device such as a drive backplane. 
     After this step is completed, a complete micro LED chip packaging module is obtained. The module may be mechanically and electrically connected to another module such as a drive backplane or a display driver integrated circuit (DDIC) or a drive system by using the pad  270 , to obtain a complete display. 
     When the micro LED chip packaging module is driven by an external drive signal, the drive signal first controls the micro IC  180 , and then the micro IC  180  controls, based on the drive signal, a working state of at least one micro LED chip  130  connected to the micro IC. This can reduce a quantity of pads between the micro LED chip packaging module and an external device such as a drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, or even far greater than a size of the micro LED chip, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     In an embodiment, as shown in  FIG.  8   , after the micro LED chip  130  and the micro IC  180  are transferred to the first base plate  170 , and before the surfaces of the micro LED chip  130 , the micro IC  180 , and the first base plate  170  are coated with the transparent packaging layer  210 , that is, between step S 105  and step S 106 , a light isolation structure  280 , a black matrix (black matrix), and the like may be fabricated between adjacent pixels, or between the micro LED chips  130 , or between the micro LED chip  130  and the micro IC  180 , to prevent light ray leakage from a gap between the pixels, reduce crosstalk between the pixels, increase or converge a visual angle of light emitting of the micro LED chip  130 , and improve light emitting efficiency, and the like, thereby improving display effect of the micro LED display. 
     In an embodiment, as shown in  FIG.  9   , when one pixel includes a plurality of micro LED chips  130  emitting same chromatic light, to obtain full-color pixels, after the micro LED chip  130  and the micro IC  180  are transferred to the first base plate  170 , and before the surfaces of the micro LED chip  130 , the micro IC  180 , and the first base plate  170  are coated with the transparent packaging layer  210 , that is, between steps S 105  and S 106 , surfaces of some or all of the micro LED chips  130  in the pixels may alternatively be coated with a color conversion material  290 , so that different micro LED chips  130  emit different chromatic light by using the color conversion material. For example, when the pixel includes three micro LED chips  130  emitting blue chromatic light, one of the micro LED chips  130  may be coated with a red color conversion material  290 , and the other micro LED chip  130  may be coated with a green color conversion material  290 . In this way, the three micro LED chips  130  in the pixel finally emit red, green, and blue light, to form a full-color RBG pixel. 
     In an embodiment, as shown in  FIG.  10   , before coating with the color conversion material  290 , the light isolation structure  280 , the black dot matrix (black matrix), or the like may be first fabricated between pixels, between micro LED chips  130 , or between the micro LED chip  130  and the micro IC  180 , to separate color conversion materials  290  of different colors, and finally improve display effect of the LED chip packaging module and a display including the LED chip packaging module. 
     In an embodiment, as shown in  FIG.  11   , after the surfaces of the micro LED chip  130 , the micro IC  180 , and the first base plate  170  are coated with the transparent packaging layer  210  (that is, after step S 106 ), a micro-nano structure  310  may be further fabricated on the packaging plane  240  of the transparent packaging layer  210 , to improve light emitting efficiency of the micro LED display, improve a light emitting field pattern, or improve another optical features. For example, the micro-nano structure  310  may be, for example, a densely arranged stripe-shaped protrusion structure. 
     An embodiment of this disclosure further provides an LED chip packaging module. The LED chip packaging module may be obtained by using the foregoing method described in the embodiments of this disclosure, or may be obtained by using another fabrication method. 
       FIG.  12    is a schematic diagram of a structure of an LED chip packaging module according to an embodiment of this disclosure. As shown in  FIG.  12   , the LED chip packaging module includes an RDL  220 , a plurality of micro LED chips  130 , at least one micro IC  180 , and a transparent packaging layer  210 . 
     The plurality of micro LED chips  130  and the at least one micro IC  180  are distributed on an upper surface  320  of the RDL  220 . Each micro LED chip  130  is provided with at least one electrode  140  that faces the upper surface  320  of the RDL  220  and that is connected to the RDL  220 . Each micro IC  180  is provided with at least one electrode  230  that faces the upper surface  320  of the RDL  220  and that is connected to the RDL  220 . Each micro IC  180  is electrically connected to at least one micro LED chip  130  by using the RDL  220 . The upper surface  320  of the RDL  220  is coated with the transparent packaging layer  210 . A thickness of the transparent packaging layer  210  in a direction perpendicular to the upper surface  320  of the RDL  220  is greater than or equal to a thickness of the micro LED chip  130  and the micro IC  180  in the direction perpendicular to the upper surface  320  of the RDL  220 . Therefore, the transparent packaging layer  210  can cover the micro LED chip  130  and the micro IC  180 , and the transparent packaging layer  210  may further form a packaging plane  240  parallel to the RDL  220  through polishing. At least one pad  270  is further disposed on a lower surface  260  of the RDL  220 . Each pad  270  is electrically connected to the at least one micro IC  180  by using the RDL  220 . A bump (bump)  330  may be further fabricated for each pad  270 , to solder the pad  270  of the RDL  220  to a pad on a drive backplane of a display, so that the LED chip packaging module is mechanically and electrically connected to the drive backplane. 
     In this embodiment of this disclosure, the micro IC  180  may be disposed in a plurality of manners relative to the RDL  220 . For example: 
     (1) All of the micro ICs  180  may be disposed on the upper surface  320  of the RDL  220 , as shown in  FIG.  12   . 
     (2) All of the micro ICs  180  may be disposed on the lower surface  260  of the RDL  220 . In this configuration manner, only the micro LED chip  130  needs to be disposed on the upper surface  320  of the RDL  220 , and no space needs to be reserved for the micro IC  180 . This improves pixel density of the LED chip packaging module and improves display effect. In addition, the micro IC  180  may have larger disposing space and a more flexible layout manner on the lower surface  260  of the RDL  220 . Therefore, the micro IC  180  with a larger size and stronger performance may be disposed, thereby improving performance of the LED chip packaging module. 
     (3) Some of the micro ICs  180  are disposed on the upper surface  320  of the RDL  220 , and the other micro ICs  180  are disposed on the lower surface  260  of the RDL  220 . In this configuration manner, the micro IC  180  on the upper surface  320  and the micro IC  180  on the lower surface  260  may each control some of the micro LED chips  130 . The micro IC  180  on the upper surface  320  and the micro IC  180  on the lower surface  260  may control same or different micro LED chips  130 . In this configuration manner, the upper surface  320  of the RDL  220  only needs to reserve space for some of the micro ICs  180 . This improves pixel density of the LED chip packaging module and improves display effect. In an implementation, a small-sized micro IC  180  may be disposed on the upper surface  320  of the RDL  220 . A large-sized micro IC  180  may be disposed on the lower surface  260  of the RDL  220 . This maximizes surface space utilization of the RDL  220 . 
     It should be noted that when the micro IC  180  is disposed on the lower surface  260  of the RDL  220 , a height of the micro IC  180  in a direction perpendicular to the lower surface  260  should be less than a sum of heights of the pad  270  and the bump  330 . In this way, the micro IC  180  does not affect soldering of the LED chip packaging module to the drive backplane of the display. 
     In an embodiment, as shown in  FIG.  12   , the RDL  220  includes an insulation flat layer  221  and a plurality of RDL lines distributed at the insulation flat layer  221 . For ease of description, the RDL lines are divided into a first RDL line  222  and a second RDL line  223  based on different directions of the RDL lines and devices connected to the RDL lines. Two ends of the first RDL line  222  are respectively referred to as a first end  2221  and a second end  2222 . Two ends of the second RDL line  223  are respectively referred to as a third end  2231  and a fourth end  2232 . The first end  2221  and the second end  2222  of the first RDL are located on the upper surface  320  of the RDL  220 . The third end  2231  of the second RDL line  223  is located on the upper surface  320  of the RDL  220 . The fourth end  2232  of the second RDL line  223  is located on the lower surface  260  of the RDL  220 . A pad  270  may be disposed at the fourth end  2232  of the second RDL line  223 , to be electrically connected to another device. The first end  2221  of the first RDL line  222  is configured to connect to the electrode  140  of the micro LED chip  130 . Each first RDL line  222  may have at least one first end  2221 , configured to connect to an electrode  140  of at least one micro LED chip  130 . The second end  2222  of the first RDL line  222  is configured to connect to the electrode  230  of the micro IC  180 . An electrode  230  of each micro IC  180  may be connected to a second end  2222  of at least one first RDL line  222 . The third end  2231  of the second RDL line  223  is configured to connect to the electrode  230  of the micro IC  180 . A third end  2231  of each second RDL line  223  may be connected to an electrode  230  of at least one micro IC  180 . The second end  2222  of the first RDL line  222  and the third end  2231  of the second RDL line  223  are connected to different electrodes  230 . A bump  330  is disposed on the pad  270  of the fourth end  2232  of the second RDL line  223 , to connect to an external device and receive an external drive signal. 
     When the micro LED chip packaging module provided in this embodiment of this disclosure is driven by an external drive signal, the drive signal first controls the micro IC  180 , and then the micro IC  180  controls, based on the drive signal, a working state of at least one micro LED chip  130  connected to the micro IC. This can reduce a quantity of I/O pads between the micro LED chip packaging module and an external device such as a drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, or even far greater than a size of the micro LED chip, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     In an embodiment, as shown in  FIG.  13   , micro LED chips  130  in the LED chip packaging module may form a plurality of pixels in a specific arrangement manner. Each pixel includes at least one micro LED chip  130 . To form a full-color pixel arrangement, each pixel may include three micro LED chips  130 , for example, a micro LED chip B emitting blue chromatic light, a micro LED chip G emitting green chromatic light, and a micro LED chip R emitting red chromatic light. The three chips may be located in a same row to form a standard RGB arrangement. In addition, each pixel may further include a micro IC  180 . The micro IC  180  is electrically connected to the three micro LED chips  130  in the pixel by using the RDL  220 , and is configured to control working states of the three micro LED chips  130 , for example, a lighting time point and intensity. Therefore, the pixel ca display various colors. In this case, each micro IC  180  is configured to control a working state of only one pixel. 
     In an embodiment, as shown in  FIG.  14   , each pixel may include three micro LED chips  130  and one micro IC  180 . The three micro LED chips  130  may be located in a same row to form a standard RGB arrangement. The micro IC  180  may be separately disposed in another row. 
     It may be understood that, in addition to the arrangement manner shown in this embodiment of this disclosure, the micro LED chip  130  may have another arrangement manner, for example, a pentile arrangement or a RGB-Delta arrangement. This is not limited in embodiments of this disclosure. 
     In an embodiment, as shown in  FIG.  15   , each pixel may include three micro LED chips  130 , to form a standard RGB arrangement. In each row or column of pixels, one micro IC  180  may be disposed for every N (N is a positive integer greater than 1) pixels. Each micro IC  180  may be electrically connected to micro LED chips  130  in N pixels adjacent to a row or column in which the micro IC  180  is located by using the RDL, to control working states of the micro LED chips  130  in the N pixels adjacent to the micro IC  180 . 
     It may be understood that, when each micro IC  180  is configured to control color rendering of the N pixels, the micro IC  180  may alternatively configure pixels in another distribution manner. Each micro IC  180  may be electrically connected to a plurality of pixels adjacent to the micro IC  180  by using the RDL, to control color rendering of these pixels. This is not limited in embodiments of this disclosure. 
     In an embodiment, as shown in  FIG.  16   , some or all of the micro LED chips  130  in each pixel may be micro LED chips emitting same chromatic light. In this case, surfaces of the some or all of the micro LED chips  130  may be coated with a color conversion material. The color conversion material converts the chromatic light emitted by the micro LED chip  130  into another color. For example, when one pixel includes three micro LED chips  130  emitting blue chromatic light, to obtain a full-color pixel, a surface of one of the micro LED chips  130  may be coated with a red color conversion material  290 R, to convert the blue light emitted by the micro LED chip  130  into red light. A surface of another micro LED chip  130  may be coated with a green color conversion material  290 G, to convert the blue light emitted by the micro LED chip  130  into green light. 
     In an embodiment, as shown in  FIG.  16   , a light isolation structure  280  may be further disposed between the micro LED chip  130  and the micro IC  180 . The light isolation structure  280  may alternatively be disposed between two adjacent micro LED chips  130 . One end of the light isolation structure  280  is connected to the RDL  220 , and the other end extends in a direction away from the RDL  220 . The light isolation structure  280  improves light emitting efficiency of the micro LED chip  130 , reduces crosstalk between pixels, increases or converges a light emitting visual angle of the micro LED chip  130 , separates color conversion materials  290  of different colors, and finally improves display effect of the LED chip packaging module and a display including the LED chip packaging module. 
     It may be understood that, to improve display effect of the LED chip packaging module and a display including the LED chip packaging module, the LED chip packaging module may include a structure such as a black matrix in addition to the light isolation structure  280 . This is not limited in embodiments of this disclosure. 
     In some embodiments, the packaging plane  240  of the transparent packaging layer  210  has a micro-nano structure  310 . The micro-nano structure  310  may be, for example, a densely arranged stripe-shaped protrusion structure. The micro-nano structure  310  improves light emitting efficiency of the micro LED display, improves a light emitting field pattern, and improves another optical feature. 
     In an embodiment, each pixel of the LED chip packaging module may further include at least one secondary micro LED chip. When detecting the LED chip packaging module and finding that a primary micro LED chip in a pixel fails, the micro IC may drive the secondary micro LED chip of the pixel to take over the job of the failed micro LED chip. In this way, the pixel can still display colors normally, thereby maintaining display integrity of the LED chip packaging module and improving a yield of the LED chip packaging module. 
     In an embodiment, as shown in  FIG.  17   , each primary micro LED chip in a pixel may correspond to a secondary micro LED chip whose light emitting color is the same as a light emitting color of the primary micro LED chip. Therefore, one full-color pixel may include six micro LED chips, that is, two micro LED chips R 1  and R 2  that emit red chromatic light, two micro LED chips G 1  and G 2  that emit green chromatic light, and two micro LED chips B 1  and B 2  that emit blue chromatic light. When all primary micro LED chips are normal, the secondary micro LED chips do not work. The micro IC drives only the primary chips to work. When any primary micro LED chip fails, the micro IC drives a secondary micro LED chip of the same color to take over the job of the failed micro LED chip. 
     For example, when the primary micro LED chip G 1  emitting the green chromatic light fails, but is in an off state or a leakage current is lower than a threshold (the threshold may be, for example, 1% of a normal drive current), the micro IC may directly drive the secondary micro LED chip G 2  emitting the green chromatic light. When the primary micro LED chip G 1  emitting the green chromatic light fails, but is in an on state or a leakage current is higher than the threshold, a laser may first break the failed micro LED chip G 1  emitting the green chromatic light or the corresponding line, so that the failed chip becomes an off state, and then the secondary micro LED chip G 2  emitting the green chromatic light is driven. 
     In an embodiment, as shown in  FIG.  18   , because a failure probability of two micro LED chips in a pixel is far lower than a failure probability of one micro LED chip, each pixel may also include only one secondary micro LED chip, to improve size utilization of the LED chip packaging module, improve pixel density, and reduce costs. 
     For example, one full-color pixel may include four micro LED chips, that is, a primary micro LED chip R 1  emitting red chromatic light, a primary micro LED chip G 1  emitting green chromatic light, a primary micro LED chip B 1  emitting blue chromatic light, and a secondary micro LED chip B 2 . It is assumed that the secondary micro LED chip emits blue chromatic light. When the primary micro LED chip B 1  emitting blue chromatic light fails, the micro IC can directly drive the secondary micro LED chip B 2 . When the primary micro LED chip R 1  or G 1  that emits red chromatic light or green chromatic light fails, the transparent packaging layer  210  around the secondary micro LED chip B 2  may be removed first by using a laser. Then, the color conversion material  290  whose color is the same as that of the failed micro LED chip is sprayed. In this way, the secondary micro LED chip B 2  can emit chromatic light whose color is the same as that of the failed micro LED chip after being driven by the micro IC. 
     In some other embodiments, one secondary micro LED chip may be further configured to replace a failed micro LED chip in more than one pixel, to reduce a quantity of secondary micro LED chips, improve size utilization of the LED chip packaging module, improve pixel density, and reduce costs. 
     For example, as shown in  FIG.  19   , one full-color pixel may include three micro LED chips, that is, a micro LED chip R 1  emitting red chromatic light, a micro LED chip G 1  emitting green chromatic light, and a micro LED chip B 1  emitting blue chromatic light. The three micro LED chips may be arranged in a triangle. The micro LED chip R 1  emitting the red chromatic light and the micro LED chip G 1  emitting the green chromatic light are located in a same row and disposed in parallel. The micro LED chip B 1  emitting the blue chromatic light is located above the other two chips. The secondary micro LED chip may be the micro LED chip B 2  emitting the blue chromatic light, and is disposed between micro LED chips B 1  that emit blue chromatic light of two adjacent pixels, to form an arrangement manner in which the primary micro LED chip and the secondary micro LED chip are alternately disposed in a same row. In this arrangement manner, when a micro LED chip B 1  that is of a pixel and that emits blue chromatic light fails, the micro IC may directly drive a secondary micro LED chip B 2  adjacent to the micro IC. When a micro LED chip R 1  or G 1  that is of a pixel and that emits red chromatic light or green chromatic light fails, the transparent packaging layer around a secondary micro LED chip B 2  closest to the failed chip may be removed first by using a laser. Then, the color conversion material whose color is the same as that of the failed micro LED chip is sprayed. In this way, the secondary micro LED chip B 2  can emit chromatic light whose color is the same as that of the failed micro LED chip after being driven by the micro IC. 
     For example, as shown in  FIG.  20   , three micro LED chips in a full-color pixel may form a standard RGB arrangement. Then, every two adjacent pixels in a same row or a same column are grouped into a group. A secondary micro LED chip B 2  is disposed between the two pixels, so that the secondary micro LED chip B 2  can be used to replace a failed micro LED chip in the group of pixels. 
     It may be understood that the implementations shown in  FIG.  17    to  FIG.  20    are merely used as examples to describe technical concepts of embodiments of this disclosure, and do not constitute a specific limitation on embodiments of this disclosure. In addition to the foregoing shown implementations, a person skilled in the art may further use other implementations under inspiration of the technical concepts. These implementations do not go beyond the protection scope of embodiments of this disclosure. 
     It should also be additionally noted that currently, there may be two light emitting directions of the micro LED chip. One is light emitting from a back side. In other words, a light ray emitted by the micro LED chip to an external environment does not pass through the RDL. The other is light emitting from a front side. In other words, a light ray emitted by the micro LED chip to an external environment needs to pass through the RDL. When the micro LED chip emits light from the back side, the insulation flat layer in the RDL may be made of a non-transparent material, and has an opaque feature. In this case, the insulation flat layer can absorb or reflect a light ray emitted by the micro LED chip, to improve luminosity. When the micro LED chip emits light from the front side, the insulation flat layer in the RDL may be made of a non-transparent material, and has a high penetration or a transparent feature, so that a light ray emitted by the micro LED chip can efficiently pass through the RDL, to improve luminosity. 
     An embodiment of this disclosure further provides another LED chip packaging method. As shown in  FIG.  21   , the method may include the following steps. 
     Step S 101  to step S 104  are the same as step S 101  to step S 104  shown in  FIG.  4   , and details are not described herein again. 
     Step S 110 : Detachably dispose the micro LED chip  130  on a first base plate  170 . The electrode  140  of the micro LED chip  130  is disposed to face the first base plate  170 . 
     A difference between step S 110  and step S 105  lies in that: In step S 110 , the micro IC  180  is not placed on the first base plate  107 . 
     In an embodiment, a plurality of micro LED chips  130  may be disposed on the first base plate  170  to form a plurality of pixels. Each of the pixels includes at least one of the micro LED chips  130 . 
     For example, as shown in an arrangement a in  FIG.  22   , a pixel includes a micro LED chip B emitting blue chromatic light, a micro LED chip G emitting green chromatic light, and a micro LED chip R emitting red chromatic light. The three micro LED chips are arranged in parallel in a row to form a standard RGB arrangement. 
     For example, as shown in an arrangement b in  FIG.  22   , a pixel may include four micro LED chips, for example, two micro LED chips B emitting blue chromatic light, one micro LED chip R emitting red chromatic light, and one micro LED chip G emitting green chromatic light. The four micro LED chips are arranged in a rectangular manner. A position of each micro LED chip may be considered as a corner of a rectangle. The two micro LED chips B emitting blue chromatic light are disposed in a diagonal manner. 
     A first attachment layer  190  is disposed on a surface of the first base plate  170 . This can detachably and temporarily fasten the micro LED chip  130  without damaging a device structure of the micro LED chip  130 . When the micro LED chip is detachably disposed on the first base plate  170 , an end of an electrode of the micro LED chip  130  is in contact with the first attachment layer  190  of the first base plate  170 . 
     Step S 111 : Coat surfaces of the micro LED chip  130  and the first base plate  170  with a transparent packaging layer  210 . 
     The transparent packaging layer  210  may include, for example, an epoxy resin material and a silicone resin material. The transparent packaging layer  210  needs to be cured for a period of time after coating. After curing, relative positions between the micro LED chips  130  can be fastened. In a preferred manner, a coating height of the transparent packaging layer  210  on the surface of the first base plate  170  may be higher than a height of the micro LED chip  130 . In this way, after the transparent packaging layer  210  is cured, the transparent packaging layer  210  may be polished or ground, to form a packaging plane  240  that is parallel to the first base plate  170  and that has good flatness. 
     Step S 112 : After the transparent packaging layer  210  is cured, remove the first base plate  170 , so that the transparent packaging layer  210  forms a first plane  250  that exposes the electrode of the micro LED chip  130 . 
     Because the end of the electrode of the micro LED chip  130  is in contact with the first attachment layer  190  of the first base plate  170 , after the micro LED chip  130  is separated from the first base plate  170 , the electrode of the micro LED chip  130  is exposed from the first plane  250  of the transparent packaging layer  210 . 
     Step S 113 : Fabricate an RDL  220  on the first plane  250 . 
     The RDL  220  includes an insulation flat layer and a plurality of RDL lines distributed at the insulation flat layer. The insulation flat layer may be made of silicon or a polymeric material. The RDL line may be made of a conductive material such as copper by using a semiconductor fabrication process technology such as photoetching, vapor deposition, or electroplating. The RDL line may be a single-layer line or a multi-layer line. This is not limited in embodiments of this disclosure. 
     The RDL line may be divided into two parts according to different directions of the RDL line. One end of a first part of the RDL line is connected to the electrode of the micro LED chip  130 . The other end is exposed on a lower surface  260  of the RDL  220 . Both ends of a second part of the RDL line are exposed on the lower surface  260  of the RDL  220 . 
     Step S 114 : Mount at least one micro IC  180  on the lower surface  260  of the RDL. 
     Some of electrodes of the micro ICs  180  are connected to the first part of the RDL line, to implement an electrical connection between the micro IC  180  and the at least one micro LED chip  130  by using the RDL  221 . Some of the micro ICs  180  are connected to one end of the second part of the RDL line. In this case, if an external drive signal is introduced to the other end of the second part of the RDL line, the drive signal may be transmitted to the micro IC  180 . 
     Step S 115 : Fabricate a pad  270  and a bump  330  on the lower surface  260  of the RDL  220 . 
     The pad  270  is connected to the other end of the second part of the RDL line. Therefore, the pad  270  can be electrically connected to the micro IC  180  by using the RDL. The bump  330  is fabricated on the pad  270 , so that the pad  270  is connected to an external device such as a drive backplane. 
     After this step is completed, a complete micro LED chip packaging module is obtained. The module may be mechanically and electrically connected to another module such as a drive backplane or a display driver integrated circuit (DDIC) or a drive system by using the bump  330 , to obtain a complete display. 
     When the micro LED chip packaging module is driven by an external drive signal, the drive signal first controls the micro IC  180 , and then the micro IC  180  controls, based on the drive signal, a working state of at least one micro LED chip  130  connected to the micro IC. This can reduce a quantity of I/O pads between the micro LED chip packaging module and an external device such as a drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, or even far greater than a size of the micro LED chip, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     A structure shown in  FIG.  8    to  FIG.  11    may also be added to the micro LED chip packaging module fabricated according to the method in  FIG.  21   , to implement a corresponding feature. Due to a limited length of this specification, details are not further described herein. 
     An embodiment of this disclosure further provides an LED chip packaging module. The LED chip packaging module may be obtained by using the method, for example, shown in  FIG.  21   , in embodiments of this disclosure, or may be obtained by using another fabrication method. 
       FIG.  23    is a schematic diagram of still another structure of an LED chip packaging module according to an embodiment of this disclosure. As shown in  FIG.  24   , the LED chip packaging module includes an RDL  220 , a plurality of micro LED chips  130 , at least one micro IC  180 , and a transparent packaging layer  210 . 
     The plurality of micro LED chips  130  are distributed on an upper surface  320  of the RDL  220 . Each micro LED chip  130  is provided with at least one electrode  140  that faces the upper surface  320  of the RDL  220  and that is connected to the RDL  220 . The at least one micro IC  180  is distributed on a lower surface  260  of the RDL  220 . Each micro IC  180  is provided with at least one electrode  230  that faces the lower surface  260  of the RDL  220  and that is connected to the RDL  220 . Each micro IC  180  is electrically connected to at least one micro LED chip  130  by using the RDL  220 . The upper surface  320  of the RDL  220  is coated with the transparent packaging layer  210 . A thickness of the transparent packaging layer  210  in a direction perpendicular to the upper surface  320  of the RDL  220  is greater than or equal to a thickness of the micro LED chip  130  in the direction perpendicular to the upper surface  320  of the RDL  220 . Therefore, the transparent packaging layer  210  can cover the micro LED chip  130 , and the transparent packaging layer  210  may further form a packaging plane  240  parallel to the RDL  220  through polishing. At least one pad  270  is further disposed on a lower surface  260  of the RDL  220 . Each pad  270  is electrically connected to the at least one micro IC  180  by using the RDL  220 . A bump (bump)  330  may be further fabricated for each pad  270 , to solder the pad  270  of the RDL  220  to a pad on a drive backplane of a display, so that the LED chip packaging module is mechanically and electrically connected to the drive backplane. 
     Further, as shown in  FIG.  23   , the RDL  221  includes an insulation flat layer  221  and a plurality of RDL lines distributed at the insulation flat layer  221 . For ease of description, the RDL lines are divided into a first RDL line  222  and a second RDL line  223  based on different directions of the RDL lines and devices connected to the RDL lines. Two ends of the first RDL line  222  are respectively referred to as a first end  2221  and a second end  2222 . Two ends of the second RDL line  223  are respectively referred to as a third end  2231  and a fourth end  2232 . The first end  2221  of the first RDL line  222  is located on the upper surface  320  of the RDL  220 . The second end  2222  of the first RDL line  222  is located on the lower surface  260  of the RDL  220 . The third end  2231  and the fourth end  2232  of the second RDL line  223  are located on the lower surface  260  of the RDL  220 . A pad may be disposed at the fourth end  2232  of the second RDL line  223 , to be electrically connected to another device. The first end  2221  of the first RDL line  222  is configured to connect to the electrode  140  of the micro LED chip  130 . Each first RDL line  222  may have at least one first end  2221 , configured to connect to an electrode  140  of at least one micro LED chip  130 . The second end  2222  of the first RDL line  222  is configured to connect to the electrode  230  of the micro IC  180 . An electrode  230  of each micro IC  180  may be connected to a second end  2222  of at least one first RDL line  222 . The third end  2231  of the second RDL line  223  is configured to connect to the electrode  230  of the micro IC  180 . A third end  2231  of each second RDL line  223  may be connected to an electrode  230  of at least one micro IC  180 . The second end  2222  of the first RDL line  222  and the third end  2231  of the second RDL line  223  are connected to different electrodes  230 . A bump  330  is disposed on the pad  270  of the fourth end  2232  of the second RDL line  223 , to connect to an external device and receive an external drive signal. 
     When the micro LED chip packaging module provided in this embodiment of this disclosure is driven by an external drive signal, the drive signal first controls the micro IC  180 , and then the micro IC  180  controls, based on the drive signal, a working state of at least one micro LED chip  130  connected to the micro IC. This can reduce a quantity of I/O pads between the micro LED chip packaging module and an external device such as a drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, or even far greater than a size of the micro LED chip, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     In this embodiment of this disclosure, the micro LED chips  130  may form a standard RGB arrangement, a pentile arrangement, an RGB-Delta arrangement, an arrangement manner shown in  FIG.  17    to  FIG.  20   , or another arrangement manner. Details are not described herein again. 
     An embodiment of this disclosure further provides another LED chip packaging method. As shown in  FIG.  24   , the method includes step S 101  to step S 104  and step S 110  to step S 112  that are the same as those in  FIG.  21   . 
     Step S 116 : Fabricate an RDL  220  on the first plane  250 . 
     The RDL  220  includes an insulation flat layer and a plurality of RDL lines distributed at the insulation flat layer. One end of each RDL line is connected to an electrode  140  of at least one micro LED chip. The other end is exposed on the lower surface  260 . 
     Step S 117 : Fabricate, on the lower surface  260 , a pad  270  connected to the RDL line. 
     Each pad  270  may be connected to one or more RDL lines. When each pad is connected to a plurality of RDL lines, the pad  270  may be in an irregular shape based on different exposed positions that is of the RDL lines connected to the pad  270  and that is on the lower surface  260 . 
     After this step is completed, a complete micro LED chip packaging module is obtained. The module may be mechanically and electrically connected to another module such as a drive backplane or a display driver integrated circuit (DDIC) or a drive system by using the pad  270 , to obtain a complete display. 
     When the micro LED chip packaging module is driven by an external drive signal, the drive signal is directly sent to at least one micro LED chip  130  by using a pad  270  and the RDL  220 , so that one drive signal controls one or more micro LED chips  130 . This can reduce a quantity of pads between the packaging module and an external device such as a drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, or even far greater than a size of the micro LED chip, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     An embodiment of this disclosure further provides an LED chip packaging module. The LED chip packaging module may be obtained by using the method, for example, shown in  FIG.  24   , in embodiments of this disclosure, or may be obtained by using another fabrication method. 
       FIG.  25    is a schematic diagram of yet another structure of an LED chip packaging module according to an embodiment of this disclosure. As shown in  FIG.  25   , the LED chip packaging module includes an RDL  220 , a plurality of micro LED chips  130  and a transparent packaging layer  210 . 
     The plurality of micro LED chips  130  are distributed on an upper surface  320  of the RDL  220 . Each micro LED chip  130  is provided with at least one electrode  140  that faces the upper surface  320  of the RDL  220  and that is connected to the RDL  220 . The upper surface  320  of the RDL  220  is coated with the transparent packaging layer  210 . A thickness of the transparent packaging layer  210  in a direction perpendicular to the upper surface  320  of the RDL  220  is greater than or equal to a thickness of the micro LED chip  130  in a direction perpendicular to the upper surface  320  of the RDL  220 . Therefore, the transparent packaging layer  210  can cover the micro LED chip  130 , and the transparent packaging layer  210  may further form a packaging plane  240  parallel to the RDL  220  through polishing. At least one pad  270  is further disposed on a lower surface  260  of the RDL  220 . Each pad  270  is electrically connected to the at least one micro LED chip  130  by using the RDL  220 . The at least one pad  270  may be soldered with a pad  340  on a drive backplane  300  of a display, so that the LED chip packaging module is mechanically and electrically connected to the drive backplane. 
       FIG.  26    is an example diagram of a pad and an RDL line of an LED chip packaging module. As shown in  FIG.  26   , when one pixel includes three micro LED chips, and each micro LED chip includes a p-type ohmic electrode and an n-type ohmic electrode, a quantity of pads  270  corresponding to the micro LED chip may be 4. The p-type ohmic electrode of each micro LED chip may correspond to one pad  270 . Each p-type ohmic electrode is connected to a pad  270  corresponding to the p-type ohmic electrode by using an RDL line  224 . In addition, another pad  270  may be connected to three n-type ohmic electrodes of three micro LED chips by using an additional RDL line  225 . Therefore, one pixel needs only four external pads  270 . If the method shown in  FIG.  1    is used, one pixel needs six external pads. It can be learned that the LED chip packaging module provided in this embodiment of this disclosure can reduce a quantity of external I/O pads. In addition, because the quantity of external I/O pads of the LED chip packaging module is reduced, when a size of the LED chip packaging module remains unchanged, a size of the pad  270  may be enlarged, and a size of a pad  340  that is on the drive backplane  300  and that is aligned with the pad  270  may be enlarged (as shown in  FIG.  25   ), to reduce bonding difficulty between the LED chip packaging module and the drive backplane  300 , and improve a product yield. 
     When the micro LED chip packaging module provided in this embodiment of this disclosure is driven by an external drive signal, the drive signal is directly sent to at least one micro LED chip  130  by using a pad  270  and the RDL  220 , so that one drive signal controls one or more micro LED chips  130 . This can reduce a quantity of pads between the packaging module and an external device such as a drive backplane. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, or even far greater than a size of the micro LED chip, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. 
     In this embodiment of this disclosure, the micro LED chips  130  may form a standard RGB arrangement, a pentile arrangement, an RGB-Delta arrangement, an arrangement manner shown in  FIG.  17    to  FIG.  20   , or another arrangement manner. Details are not described herein again. 
     It may be understood that, according to embodiments of the LED chip packaging module provided in this disclosure, two or three of the structures shown in  FIG.  12   ,  FIG.  23   , and  FIG.  25    may also appear in one LED chip packaging module at the same time. Due to a limited length of this specification, this is not further described in this embodiment of this disclosure. 
     An embodiment of this disclosure further provides a micro LED display. As shown in  FIG.  27   , the display may include a drive backplane  300 , a DDIC  400 , and at least one LED chip packaging module  200  provided in the foregoing embodiments of this disclosure. 
     The drive backplane  300  may be, for example, a glass backplane, a thin film base plate, a plastic backplane, or a TFT backplane. Correspondingly, the DDIC  400  may be packaged on the drive backplane  300  by using a packaging technology such as chip on plastic (COP) packaging technology, chip on film (COF) packaging technology, or chip on glass (COG) packaging technology. 
     A plurality of pads  340  are disposed on the drive backplane  300 , and these pads  340  are in a one-to-one correspondence with positions of pads  270  of the LED chip packaging module  200 . The LED chip packaging module  200  and the drive backplane  300  may be packaged together by using a packaging technology such as an SMT. Therefore, the pads  340  on the drive backplane  300  and the pads  270  of the LED chip packaging module  200  are soldered together in a one-to-one correspondence, to form electrical and mechanical connections. The pads  340  on the drive backplane  300  are further connected to the DDIC  400  by using a line, so that a drive signal of the DDIC  400  can be sent to the LED chip packaging module  200 . 
     In an embodiment, the micro LED display may include only one LED chip packaging module  200 . This type of display may be applied to, for example, an electronic device having a small-sized display, such as a smart band or a smartwatch. In this case, a quantity of the pads  340  of the drive backplane  300  may be the same as a quantity of pads  270  of one LED chip packaging module  200 . Alternatively, a quantity of pads  340  may be not less than a quantity of pads  270  of one LED chip packaging module  200 . 
     According to the technical solution of this embodiment of this disclosure, when the micro LED display includes one LED chip packaging module  200 , and the LED chip packaging module  200  includes X (column)×Y (row) pixels, a quantity range of external pads  270  of the LED chip packaging module  200  may be between X+Y and X×Y×Z, where Z is a quantity of external I/Os of each pixel. Correspondingly, a quantity of pads  340  of the drive backplane  300  may also be between X+Y and X×Y×Z. 
     For example, when the DDIC  400  drives each pixel in the LED chip packaging module  200  by using a scan line and a data line architecture, a quantity of external pads  270  of the LED chip packaging module  200  may be only X+Y+M, where M is a few necessary pads such as pads corresponding to a clock signal (clock) and a ground signal (ground). Correspondingly, a quantity of pads  340  of the drive backplane may also be X+Y+M. 
     In an embodiment, the micro LED display may include only a plurality of LED chip packaging modules  200 . The plurality of LED chip packaging modules  200  are spliced on the drive backplane  300  to form a completed display area. For example, this type of display may be applied to an electronic device having a small size and a large size, for example, a smart band, a smart watch, a mobile phone, a tablet computer, an e-reader, a television, a display, and a virtual/hybrid/augmented reality device. In this case, a quantity of the pads  340  of the drive backplane  300  may be the same as a total quantity of pads  270  of the plurality of LED chip packaging module  200 . Alternatively, a quantity of pads  340  may be not less than a total quantity of pads  270  of the plurality of LED chip packaging module  200 . 
     According to the technical solution of this embodiment of this disclosure, when the micro LED display includes K LED chip packaging modules  200 , and each LED chip packaging module  200  includes X (column)×Y (row) pixels, a total quantity range of external pads  270  of the K LED chip packaging modules  200  may be between (X+Y)×K and X×Y×Z×K, where Z is a quantity of external I/Os of each pixel. Correspondingly, a quantity of pads  340  of the drive backplane  300  may also be between (X+Y)×K and X×Y×Z×K. 
     For example, when the DDIC  400  drives each pixel in the LED chip packaging module  200  by using a scan line (scan line) and a data line (data line) architecture, a quantity of external pads  270  of each LED chip packaging module  200  may be only X+Y+M, where M is a few necessary pads such as pads corresponding to a clock signal (clock) and a ground signal (ground). Correspondingly, a quantity of pads  340  of the drive backplane  300  may also be (X+Y+M)×K. 
     Further, as shown in  FIG.  28   , it should be additionally noted that, when two adjacent LED chip packaging modules  200  are spliced, to prevent a splicing gap or offset between the two LED chip packaging modules  200  from being perceived by a user, a spacing Y 1  between two adjacent micro LED pixels between the two adjacent LED chip packaging modules  200  may be within a specific range, and is preferably between 0.5 and 2 times a pixel spacing Y 0  in the LED chip packaging module  200 . In addition, an angle deviation Δθ between the two adjacent LED chip packaging modules  200  is less than a specific angle threshold. The threshold is preferably 5°, to achieve effect of seamless splicing of the two adjacent LED chip packaging modules  200  from a perspective of user perception. 
     For example, for a general display, a black matrix or another light isolation structure may be disposed between pixels. A width of the light isolation structure forms a part of a pixel spacing. However, when edges of the two LED chip packaging modules  200  to be spliced are pixels, the two LED chip packaging modules  200  may be first spliced, and then the light isolation structure is fabricated at a splicing position. Therefore, during splicing, due to factors such as alignment tolerance, a distance between an edgemost chip (a micro LED chip or a micro IC) of one LED chip packaging module  200  and an edgemost chip (a micro IC or a micro LED chip) of another LED chip packaging module  200  may be less than a width of the light isolation structure. In this case, the spacing between the two adjacent micro LED pixels at the module splicing position is less than the pixel spacing in the LED chip packaging module  200 . 
     For example, for a display with a pixel density of 300 pixels per inch (pixel per inch, ppi), a pixel spacing may be 80 μm. If a size of a micro LED chip is 10 μm, and a spacing between RGB chips is 5 μm, it may be deduced that a distance between a rightmost micro LED chip emitting red light of a pixel and a leftmost micro LED chip emitting blue light of an adjacent pixel is 30 μm. Therefore, as long as edges of the two LED chip packaging modules  200  to be spliced do not include the light isolation structure and a distance between the edges is less than 40 μm during splicing, the distance between two adjacent micro LED pixels at a module splicing position can be less than 80 μm, and a limit can reach 40 μm. 
     An embodiment of this disclosure further provides an electronic device. The electronic device includes any display or LED chip packaging module provided in the foregoing embodiments of this disclosure. In some embodiments, the electronic device may include a mobile phone, a tablet computer, a smart band, a smart watch, an e-reader, a television, a display, a virtual/hybrid/augmented reality device, a smart home device (for example, a smart speaker or a smart peephole) with a display, a home appliance device (for example, a refrigerator, an air purifier, a washing machine, or a water heater) with a display, and a traffic device (for example, an in-vehicle infotainment system, an autonomous driving platform, and a dashcam) with a display. 
     In addition, the electronic device provided in this embodiment of this disclosure may further include other components such as a processor, a memory, a battery, a speaker, an earpiece, and a camera. This is not specifically limited herein. 
     The technical solutions provided in embodiments of this disclosure have the following beneficial effect. 
     First, in the technical solutions provided in embodiments of this disclosure, a micro-nano bonding process is not used in a process of fabricating an LED chip packaging module. A micro bump does not need to be fabricated on an electrode of a micro LED chip. This avoids a problem that a device feature is affected because a solder material of the micro bump is diffused to an ohmic metal layer, improves a production yield, and avoid a problem that a packaging process of an LED chip with a high PPI is difficult due to a limitation of the micro-nano bonding process. In addition, because the micro-nano bonding process is not used, a total thickness of pixels is reduced, and a depth-to-width ratio of the total thickness of pixels to a distance between the pixels is reduced. Therefore, an optical process between micro LED chips or pixels or a volumization process of another device becomes easier, which improves a production yield. 
     In addition, in the technical solutions provided in embodiments of this disclosure, compared with a conventional micro-nano bonding process technology, a quantity of I/O pads on an LED chip packaging module and a drive backplane is significantly reduced. Therefore, for the LED chip packaging module and the drive backplane that have a same size, a size of each pad may be larger, or even far greater than a size of the micro LED chip, to greatly reduce bonding difficulty between the LED chip packaging module and the drive backplane, and improve a product yield. For example, it is assumed that each pixel of the LED chip packaging module includes three micro LED chips, and a spacing between pixels is 0.1 mm. If a module includes 100×100 pixels, 10,000 pixels in total, a size of the entire module is 10 mm×10 mm. There are 30,000 micro LED chips in total. To fabricate this module, if a conventional micro-nano bonding process is used, each micro LED chip includes at least two electrodes: a positive electrode and a negative electrode. Therefore, at least 60,000 pads need to be placed in a 10 mm×10 mm area. When a fan-shaped package design is used, a maximum area and a maximum diameter of each pad are about 0.00167 mm 2  and 0.04 mm. A very small size causes very high process difficulty. However, if the method provided in embodiments of this disclosure is used, for example, three micro LED chips in each pixel are controlled by one micro IC to light up time or intensity. A DDIC of the drive backplane only needs to perform I/O communication with the micro IC, for example, notify, in a scanning manner, each micro IC that a color, brightness, and the like of the micro LED chip need to be controlled. Therefore, the LED chip packaging module only needs to be provided with a pad configured to perform I/O communication with the DDIC. A signal transmitted from the DDIC to the micro IC is programmable and only need to meet a specific display architecture. For example, if scan line and data line architectures are used to sequentially operate each group of pixels in the LED chip packaging module, the I/Os required by the LED chip packaging module for receiving external input signals or currents include only 100 I/Os corresponding to a scan line, 100 I/Os corresponding to a data line, and a few necessary clock signals (clock) and ground signals (ground). Therefore, a total quantity of external pads of the LED chip packaging module can be reduced to less than 300. In an extreme case, the quantity of external pads can reach 200. A maximum quantity of external pads is 100×100×Z, where Z indicates a quantity of external I/Os of each pixel. It can be learned that, in a 10 mm×10 mm area, a maximum area and a maximum diameter of each pad may reach 0.33 mm 2  and 0.577 mm. Therefore, a size of an external pad of the LED chip packaging module may be far greater than a size of the micro LED chip, thereby greatly reducing bonding difficulty between the LED chip packaging module and the drive backplane, and even implementing bonding by using a simpler SMT process. 
     In addition, the LED chip packaging module already includes micro ICs that can drive a small quantity of micro LED chips. The micro ICs of the micro LED chips form a drivable loop by using an RDL. Therefore, a probe may be used to input a drive signal from an I/O pad of the LED chip packaging module to directly perform display effect detection on the LED chip packaging module, to select LED chip packaging modules that have no defect or that have similar optoelectronic features, and combine the LED chip packaging modules into a display, thereby improving a yield rate and utilization. 
     In addition, the micro LED chip of the LED chip packaging module is fastened by using a transparent packaging layer, and a surface on which an electrode of each micro LED chip is located is located on a same plane. Therefore, heights and tilt angles of all micro LED chips can be consistent, thereby improving display uniformity.