Inverted Mini LED chip and preparation method thereof, Mini LED device and preparation method thereof

Abstract

The invention relates to the technical field of LED packaging, and discloses an inverted Mini LED chip and a preparation method thereof, and a Mini LED device and a preparation method thereof, and the preparation method of the inverted Mini LED chip comprises the steps: providing an inverted Mini LED chip wafer; arranging a first buffer film on one side, far away from the chip layer, of the substrate, arranging a first blue film on the first buffer film, and cutting the substrate and the first buffer film to obtain a single flip Mini LED chip; carrying out a spot measurement test; arranging a second buffer film on the chip layer, and cutting; expanding the film to reach a preset distance; sorting is carried out, and sorting is carried out to different second blue films; a third blue film is arranged on the second buffer film, the first buffer film and the second blue film are removed, and the substrate is exposed; the first buffer film and the second buffer film each comprise a substrate layer and a UV bonding layer. According to the invention, the buffer film protects the chip layer during sorting and die bonding, the chip is prevented from being damaged due to the ejector pin, efficient stripping can be realized, and the structure of the chip layer is not damaged.

Description

Technical Field

[0001] The present invention relates to the technical field of LEDs, and in particular, to an inverted Mini LED chip and a preparation method thereof, a Mini LED device and a preparation method thereof. Background Art

[0002] Inverted Mini LED chips are widely used in the COB direct display solution. By individually controlling the RGB three primary color chips, high-definition and high-resolution displays are achieved, with significant advantages such as rich colors, energy conservation, long lifespan, and light weight. It is gradually becoming the mainstream technology in the display screen market.

[0003] Currently, the manufacturing process of inverted Mini LED chips is continuously refined. Through grinding and polishing techniques, the thickness of the chips is generally controlled within 100 μm, and the size is maintained at about 3*6 mil. During the chip production process, the Mini LED chip wafer is first cut into individual chips, followed by optoelectronic performance testing, and the chips are classified according to a specific Bin table to select chips that meet the customer's specification parameter requirements. In the packaging application link, the Mini LED chips are fixed on the substrate through die bonding technology, and then the electrical connection between the chips and the substrate is achieved through reflow soldering, while ensuring that the chips are firmly adhered to the substrate.

[0004] However, in the sorting process of inverted Mini LED chips and the die bonding process at the packaging end, there is a technical problem that needs to be solved urgently. Due to the extremely thin thickness of inverted Mini LED chips, the ejector pin and the suction nozzle need to work together during transfer, but the force of the ejector pin often causes the chips to be damaged or broken. Especially for red inverted Mini LED chips, the GaAs material used is more brittle and more likely to cause breakage, which has a greater impact on the production yield and stability of inverted Mini LED chips. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to provide an inverted Mini LED chip and a preparation method thereof, in which the buffer film protects the chip layer during sorting and die bonding, avoiding high-efficiency and rapid peeling, and does not damage the chip layer structure.

[0006] The technical problem to be solved by the present invention is also to provide a Mini LED device and a preparation method thereof, which improve the luminous efficiency and extend the service life.

[0007] To solve the above technical problems, the first aspect of the present invention provides a preparation method of an inverted Mini LED chip, including:

[0008] Provide an inverted Mini LED chip wafer, which includes a substrate and a plurality of chip layers arranged at intervals on the substrate;

[0009] A first buffer film is provided on the side of the substrate away from the chip layer, a first blue film is provided on the first buffer film, and the substrate and the first buffer film are cut to obtain single inverted Mini LED chips, and the cutting positions correspond to the intervals between adjacent chip layers;

[0010] Perform spot testing;

[0011] A second buffer film is provided on the chip layer, the second buffer film is cut, and the cutting positions correspond to the intervals between adjacent chip layers; and the film is expanded to make the distance between adjacent single inverted Mini LED chips reach a preset distance;

[0012] Perform sorting, and sort the single inverted Mini LED chips onto different second blue films;

[0013] A third blue film is provided on the second buffer film, and the first buffer film and the second blue film are removed by UV light irradiation to expose the substrate;

[0014] Wherein, both the first buffer film and the second buffer film include a substrate layer and a UV adhesive layer.

[0015] As an improvement of the above solution, performing sorting and sorting the single inverted Mini LED chips onto different second blue films includes:

[0016] Use a sorting device to test the single inverted Mini LED chips and classify them according to the test results;

[0017] Align the top needle with the surface of the first blue film of the inverted Mini LED chip to be transferred, align the suction nozzle with the surface of the second buffer film layer, transfer the single inverted Mini LED chips of the same type to the same second blue film, and arrange them at intervals on the second blue film.

[0018] As an improvement of the above solution, cutting the substrate and the first buffer film to obtain single inverted Mini LED chips includes:

[0019] Through the first buffer film, use laser stealth cutting to cut the substrate to form a splitting point, and the cutting position corresponds to the interval between adjacent chip layers;

[0020] At the corresponding position of the splitting point, cut the first buffer film, and the cutting channel penetrates the first buffer film;

[0021] Perform splitting treatment on the cut inverted Mini LED chip wafer to obtain single inverted Mini LED chips.

[0022] As an improvement of the above solution, a first buffer film is provided on the side of the substrate away from the chip layer, and the UV adhesive layer is bonded to the substrate;

[0023] A second buffer film is provided on the chip layer, and the UV adhesive layer is bonded to the chip layer;

[0024] The thickness of the substrate layer is 10μm - 100μm, the thickness of the UV adhesive layer is 3μm - 30μm, and the substrate layer is a transparent insulating layer.

[0025] As an improvement of the above solution, the thickness of the first buffer film is 13μm - 130μm, and the thickness of the substrate is 60μm - 200μm.

[0026] As an improvement of the above solution, the thickness of the second buffer film is 13μm - 130μm, the thickness of the chip layer is 5μm - 15μm, and the width of the second buffer film is greater than the width of the chip layer on a single flip-chip Mini LED chip.

[0027] As an improvement of the above solution, the chip layer includes an epitaxial layer, a current blocking layer, and a transparent conductive layer arranged in sequence. The transparent conductive layer covers the current blocking layer. A P-type electrode and a groove extending to the epitaxial layer are provided on the transparent conductive layer. An N-type electrode is provided in the groove. A passivation layer and a pad are provided on the transparent conductive layer. The passivation layer covers the P-type electrode and the groove, and the pad is electrically connected to the P-type electrode and the N-type electrode after passing through the passivation layer.

[0028] The second aspect of the present invention provides a flip-chip Mini LED chip, which is prepared according to the preparation method of the flip-chip Mini LED chip described above.

[0029] The third aspect of the present invention provides a Mini LED device, including the flip-chip Mini LED chip described above.

[0030] The fourth aspect of the present invention provides a preparation method of the Mini LED device described above, including:

[0031] Transferring and die-bonding the flip-chip Mini LED chip onto a substrate;

[0032] Encapsulating the flip-chip Mini LED chip on the substrate.

[0033] Implementing the present invention has the following beneficial effects:

[0034] In the present invention, a first buffer film and a first blue film are provided on the substrate, which can isolate the direct contact between the substrate and the testing equipment, reduce the damage to the substrate caused by friction, thereby ensuring the integrity of the substrate. Moreover, during the point measurement, it can disperse the tiny vibrations or pressures generated when the probe contacts the chip electrode, protect the structure of the flip-chip Mini LED chip, and improve the light-emitting performance and electrical performance of the flip-chip Mini LED chip. Subsequently, a second buffer film is provided on the chip layer, which plays a protective role for the chip layer during sorting and subsequent die bonding operations, avoiding the failure of the flip-chip Mini LED chip due to the rigid action of the ejector pin, and further extending the service life of the chip.

[0035] In addition, both the first buffer film and the second buffer film include a substrate layer and a UV adhesive layer. They not only have good physical support and protection effects on the chip layer and the substrate, but also are tightly bonded when the buffer film contacts the substrate and the chip layer, effectively shortening the production cycle. More importantly, they can be quickly removed by UV light irradiation when not needed later, and there is no residue on the surfaces of the substrate and the chip layer, nor will they damage the structure of the chip layer. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 : Schematic structural diagram of the flip-chip Mini LED chip wafer in step (1) of the present invention;

[0037] Figure 2 : Schematic structural diagram after step (21) of the present invention is completed;

[0038] Figure 3 : Schematic structural diagram of the first buffer film or the second buffer film in the present invention;

[0039] Figure 4 : Schematic working diagram of step (22) of the present invention;

[0040] Figure 5 : Schematic working diagram of step (23) of the present invention;

[0041] Figure 6 : Schematic structural diagram after step (24) of the present invention is completed;

[0042] Figure 7 : Schematic structural diagram after step (41) of the present invention is completed;

[0043] Figure 8 : Schematic structural diagram after step (42) of the present invention is completed;

[0044] Figure 9 : Schematic working diagram of step (52) of the present invention;

[0045] Figure 10 : Schematic structural diagram after step (52) of the present invention is completed;

[0046] Figure 11 : Schematic structural diagram after step (6) of the present invention is completed;

[0047] Figure 12 : Schematic working diagram of transferring and die - bonding the flip - chip Mini LED chips onto the carrier board in the present invention.

[0048] Reference numerals: 1 - substrate; 2 - chip layer; 3 - first buffer film; 4 - first blue film; 5 - second buffer film; 6 - second blue film; 7 - third blue film; 8 - substrate layer; 9 - UV adhesive layer; 10 - splitting point; 11 - nozzle; 12 - ejector pin. Detailed implementation manners

[0049] To make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail with specific embodiments below.

[0050] To solve the above problems, the first aspect of the present invention provides a method for preparing flip - chip Mini LED chips, including:

[0051] (1) Provide a flip - chip Mini LED chip wafer, where the flip - chip Mini LED chip wafer includes a substrate 1 and a plurality of chip layers 2 arranged at intervals on the substrate 1;

[0052] (2) Set a first buffer film 3 on the side of the substrate 1 away from the chip layer 2, set a first blue film 4 on the first buffer film 3, and cut the substrate 1 and the first buffer film 3 to obtain single flip - chip Mini LED chips, and the cutting position corresponds to the interval between adjacent chip layers 2;

[0053] (3) Conduct spot - testing;

[0054] (4) Set a second buffer film 5 on the chip layer 2, cut the second buffer film 5, and the cutting position corresponds to the interval between adjacent chip layers 2; and perform film expansion to make the distance between adjacent single flip - chip Mini LED chips reach a preset distance;

[0055] (5) Conduct sorting, and sort the single flip - chip Mini LED chips onto different second blue films 6;

[0056] (6) Set a third blue film 7 on the second buffer film 5, and irradiate with UV light to remove the first buffer film 3 and the second blue film 6, exposing the substrate 1;

[0057] Among them, both the first buffer film 3 and the second buffer film 5 include a substrate layer 8 and a UV adhesive layer 9.

[0058] In the present invention, a first buffer film 3 and a first blue film 4 are provided on the substrate 1, which can isolate the direct contact between the substrate 1 and the testing equipment, reduce the damage to the substrate 1 caused by friction, thereby ensuring the integrity of the substrate 1, and can disperse the tiny vibrations or pressures generated when the probe contacts the chip electrode during point measurement, protect the structure of the flip-chip Mini LED chip, and improve the light-emitting performance and electrical performance of the flip-chip Mini LED chip. Subsequently, a second buffer film 5 is provided on the chip layer 2, which plays a protective role for the chip layer 2 during sorting and subsequent die bonding operations, and avoids the chip failure of the flip-chip Mini LED chip caused by the rigid action of the ejector pin 12, further extending the service life of the chip.

[0059] Furthermore, both the first buffer film 3 and the second buffer film 5 include a substrate layer 8 and a UV adhesive layer 9, which not only have good physical support and protection for the chip layer 2 and the substrate 1, but also are tightly bonded when the buffer film first contacts the substrate 1 and the chip layer 2, effectively shortening the production cycle. More importantly, it can be quickly removed by UV light irradiation when it is not needed later, and there is no residue on the surfaces of the substrate 1 and the chip layer 2, nor will it damage the structure of the chip layer 2.

[0060] The detailed parameters for each step are as follows. Please refer to Figures 1 to 11 。

[0061] Regarding (1), provide a flip-chip Mini LED chip wafer, and the flip-chip Mini LED chip wafer includes a substrate 1 and a plurality of chip layers 2 spaced on the substrate 1;

[0062] Preferably, as Figure 1 shown, isolation grooves are provided between the chip layers 2 to space the chip layers 2 on the substrate 1, and the isolation grooves are used to cut the flip-chip Mini LED chip wafer to form individual flip-chip Mini LED chips. Optionally, the isolation grooves can be formed by etching the epitaxial layer until the substrate 1 is exposed, and the etching process includes but is not limited to dry etching.

[0063] Furthermore, after forming the flip-chip Mini LED chip wafer, the substrate 1 is subjected to a thickness reduction treatment to make its thickness meet the requirements. Generally, the thickness of the flip-chip Mini LED chip wafer is controlled to be less than or equal to 100 μm. It can be understood that the flip-chip Mini LED chip wafer can be a red flip-chip Mini LED chip wafer, a green flip-chip Mini LED chip wafer, or a blue flip-chip Mini LED chip wafer.

[0064] In some embodiments, the chip layer 2 includes an epitaxial layer, a current blocking layer, a transparent conductive layer, a passivation layer electrode, and a pad. Optionally, the chip layer 2 includes an epitaxial layer, a current blocking layer, and a transparent conductive layer arranged in sequence, the transparent conductive layer covers the current blocking layer, a P-type electrode and a groove extending to the epitaxial layer are provided on the transparent conductive layer, an N-type electrode is provided in the groove, a passivation layer and a pad are provided on the transparent conductive layer, the passivation layer covers the P-type electrode and the groove, and the pad penetrates the passivation layer and is electrically connected to the P-type electrode and the N-type electrode. It can be understood that the pad includes a P-type pad and an N-type pad, and the P-type pad and the N-type pad penetrate the passivation layer and are electrically connected to the corresponding P-type electrode and N-type electrode.

[0065] Regarding (2), a first buffer film 3 is provided on the side of the substrate 1 away from the chip layer 2, a first blue film 4 is provided on the first buffer film 3, and the substrate 1 and the first buffer film 3 are cut to obtain a single flip-chip Mini LED chip, and the cutting position corresponds to the interval between adjacent chip layers 2;

[0066] Specifically, it includes:

[0067] (21), a first buffer film 3 is provided on the side of the substrate 1 away from the chip layer 2, as Figure 2 shown;

[0068] In this step, providing the first buffer film 3 on the substrate 1 serves as a protective layer. During multiple transfer processes, the ejector pin 12 or the suction nozzle 11 can act on the substrate 1 through the first buffer film 3, and it can also isolate the direct contact between the substrate 1 and various test instruments, protect the flatness of the surface of the substrate 1, and improve the production yield.

[0069] Preferably, the first buffer film 3 includes a substrate layer 8 and a UV adhesive layer 9, as Figure 3 shown. The substrate layer 8 is a transparent insulating layer, and the UV adhesive layer 9 is bonded to the substrate 1. At this time, the first buffer film 3 is equivalent to an electrostatic barrier, which can prevent the conduction of accumulated static electricity during the preparation process, reduce the risk of the back surface of the substrate 1 being interfered by static electricity, avoid electrical short circuits between the back surface of the substrate 1 and test equipment or other conductive objects, and at the same time prevent the reflected light at the substrate 1 from affecting the detection results. Optionally, the raw material for preparing the substrate layer 8 is a transparent insulating plastic material, which can be, for example, epoxy resin, polyimide, etc., but is not limited thereto; the UV adhesive in the UV adhesive layer will be modified and lose its viscosity under the action of UV light, thereby facilitating peeling and removal from the substrate 1.

[0070] Furthermore, the thickness of the first buffer film 3 is 13 μm - 130 μm, and the thickness of the substrate 1 is 60 μm - 200 μm. The first buffer film 3 with a specific thickness cooperates with the substrate 1, enabling the first buffer film 3 to not only play a protective role but also reduce the influence on light propagation, thereby reducing the interference with the test results. If the thickness of the first buffer film 3 is too thick, the signal may be attenuated when passing through the first buffer film 3, resulting in damage to the signal integrity of the test. Moreover, it will also affect the thermal conductivity of the substrate 1, thereby reducing the accuracy of point measurement and sorting classification. Among them, in the first buffer film 3, the thickness of the substrate layer 8 is 10 μm - 100 μm, and the thickness of the UV adhesive layer 9 is 3 μm - 30 μm, which promotes the stable bonding of the first buffer film 3 on the substrate 1, further improves the accuracy of point measurement and sorting, and increases the yield of flip-chip Mini LED chips.

[0071] (22) Through the first buffer film 3, the substrate 1 is cut by laser stealth dicing to form a splitting point 10, and the cutting position corresponds to the interval from the adjacent chip layer 2, as Figure 4 shown;

[0072] (23) At the corresponding position of the splitting point 10, as Figure 5 shown, the first buffer film 3 is cut, and the cutting channel penetrates the first buffer film 3;

[0073] In this step, the cutting method can be dicing wheel cutting, UV light positive scribing, etc.

[0074] (24) A first blue film 4 is set on the first buffer film 3, and the cut flip-chip Mini LED chip wafer is split to obtain single flip-chip Mini LED chips, as Figure 6 shown;

[0075] In this step, according to the position of the cutting channel formed on the first buffer film 3 and the splitting point 10 formed on the substrate 1, a force is applied to the flip-chip Mini LED chip wafer to split the substrate 1, obtaining single flip-chip Mini LED chips. In the present invention, laser stealth dicing can perform precise cutting inside the substrate 1 without directly mechanically impacting the edge of the chip. By using temperature cutting methods such as dicing wheel cutting and UV light positive scribing to process the first buffer film 3, the surface of the cutting channel formed on the first buffer film 3 is made more neat and complete. The final splitting is a natural separation based on the previous cutting, which can improve the quality of the chips, effectively reduce the breakage rate of the chips during the cutting process, and increase the production yield.

[0076] Regarding (3), perform a point measurement test;

[0077] When performing the spot test, the front side of the flip-chip Mini LED chip wafer faces upward, that is, the electrode on the chip layer 2 faces upward, and a first buffer film 3 and a first blue film 4 are provided under the substrate 1 to facilitate the spot test.

[0078] Regarding (4), a second buffer film 5 is provided on the chip layer 2, and the second buffer film 5 is cut, and the cutting position corresponds to the interval between adjacent chip layers 2; and the film is expanded so that the distance between adjacent single flip-chip Mini LED chips reaches a preset distance;

[0079] Specifically include:

[0080] (41) A second buffer film 5 is provided on the chip layer 2, such as Figure 7 As shown;

[0081] In this step, a second buffer film 5 is provided on the chip layer 2 to protect the chip layer 2 and prevent the chip from directly contacting the ejector pins 12 or the nozzles 11 during movement, while buffering the pressure and effectively preventing the chip from mechanical damage.

[0082] Preferably, the second buffer film 5 includes a substrate layer 8 and a UV adhesive layer 9, wherein the substrate layer 8 is a transparent insulating layer, and the UV adhesive layer 9 is bonded to the chip layer 2, so that the fixation and operation of the chip are more convenient, and batch testing and transportation are convenient. Moreover, the transparent substrate is selected so that the second buffer film 5 does not block the light path, and a stable optical environment is maintained during the sorting test. The insulating properties of the substrate can prevent the accumulation and conduction of static electricity, and ensure that the electrical properties of the chip are not interfered by static electricity during the test. It can be understood that the raw material for preparing the substrate layer 8 is a transparent insulating plastic material, and exemplary ones may be epoxy resin, polyimide, etc. The UV adhesive in the UV adhesive layer will be modified and lose its viscosity under the action of UV light, and then it is easy to peel off and remove from the substrate 1.

[0083] Furthermore, the thickness of the second buffer film 5 is 13μm-130μm, and the thickness of the chip layer 2 is 5μm-15μm. The second buffer film 5 of a specific thickness is used in conjunction with the chip layer 2. While playing a protective role, it can also reduce the reflection of light at the interface during testing, so that the original light can smoothly pass through the second buffer film 5 and emit, thereby maintaining the luminous performance and electrical performance of the flip-chip Mini LED chip, and improving the accuracy of spot testing and sorting and classification. If the thickness of the second buffer film 5 is too thick, it will reduce the light extraction efficiency, resulting in an increase in the contact resistance between the probe and the chip layer 2, and the accuracy of the test will be reduced. Among them, in the second buffer film 5, the thickness of the substrate layer 8 is 10μm-100μm, and the thickness of the UV adhesive layer 9 is 3μm-30μm, which promotes the stable bonding of the second buffer film 5 on the chip, avoids chip offset, and further improves the accuracy of spot testing and sorting, and improves the yield of flip-chip Mini LED chips.

[0084] (42) The second buffer film 5 is cut, and the cutting position corresponds to the interval between the adjacent chip layers 2; and the film is expanded so that the distance between adjacent single flip-chip Mini LED chips reaches a preset distance, such as Figure 8 As shown;

[0085] In this step, the second buffer film 5 is cut at the interval between adjacent chip layers 2. The formed cutting path penetrates the second buffer film 5 to facilitate the expansion process. The cutting method can be wheel cutting, UV light positive scratching, etc.

[0086] Preferably, the width of the second buffer film 5 is greater than the width of the chip layer 2 on a single flip-chip Mini LED chip, thereby providing good protection for the chip layer 2 .

[0087] Regarding (5), sorting is performed to sort the single flip-chip Mini LED chips onto different second blue films 6;

[0088] Specifically include:

[0089] (51) Use sorting equipment to test a single flip-chip Mini LED chip and classify it according to the test results;

[0090] Optionally, the classification standard may be a Bin table, and classification may be performed according to parameters such as brightness, wavelength, forward voltage, etc. according to customer needs.

[0091] (52) Align the ejector pin 12 with the surface of the first blue film 4 of the flip-chip Mini LED chip to be transferred, and align the suction nozzle 11 with the surface of the second buffer film 5 layer, as shown in FIG. Figure 9 As shown, the same type of single flip-chip Mini LED chips are transferred to the same second blue film 6 and arranged at intervals on the second blue film 6, as shown in FIG.Figure 10 as shown

[0092] In this step, the first buffer film 3 and the second buffer film 5 protect the substrate 1 and the chip layer 2 respectively, avoiding direct contact with the suction nozzle 11 and the ejector pin 12. In particular, the chip layer 2 is protected, reducing the probability of damage to the chip layer 2 under the vacuum action of the suction nozzle 11.

[0093] Regarding (6), a third blue film 7 is provided on the second buffer film 5, and the first buffer film 3 and the second blue film 6 are removed by UV light irradiation, exposing the substrate 1, as Figure 11 shown

[0094] In this step, a third blue film 7 is provided on the second buffer film 5, and multiple flip-chip Mini LED chips are integrated into a whole. Subsequently, the first buffer film 3 and the second blue film 6 are removed under UV light irradiation, exposing the substrate 1, and a complete flip-chip Mini LED chip is obtained. The substrate 1 can be directly fixed on the substrate in the COB direct display application, and the operation is simple and efficient.

[0095] Correspondingly, the present invention also provides a flip-chip Mini LED chip, which is prepared according to the above preparation method.

[0096] Correspondingly, the present invention also provides a Mini LED device, including the flip-chip Mini LED chip, which has high luminous efficiency and long service life.

[0097] Correspondingly, the present invention also provides a preparation method of a Mini LED device, including:

[0098] (1) Transfer and die-bond the flip-chip Mini LED chip on the substrate;

[0099] In this step, a die bonder can be used to transfer and fix the flip-chip Mini LED chip on the substrate. Specifically, as Figure 12 shown, the ejector pin 12 is aligned with the surface of the third blue film 7, the suction nozzle 11 is aligned with the substrate 1, and the flip-chip Mini LED chip is transferred. During the transfer of the flip-chip Mini LED chip, the second buffer film 5 and the third blue film 7 effectively protect the chip layer 2, preventing the chip from failing due to the rigid action of the ejector pin 12. Subsequently, the second buffer film 5 and the third blue film 7 are peeled off under UV light irradiation to expose the electrode surface, and electrical connection between the electrode and the substrate is achieved through welding to form an electrical path.

[0100] (2) Package the flip-chip Mini LED chip on the substrate.

[0101] In this step, it includes forming a dam bracket around the flip-chip Mini LED chip on the substrate, and filling fluorescent glue, encapsulation glue, etc. in the dam bracket. The present invention is not limited thereto.

[0102] The following further illustrates the present invention with specific embodiments:

[0103] Embodiment 1

[0104] This embodiment provides a flip-chip Mini LED chip, and its preparation method includes:

[0105] (1) Provide a flip-chip Mini LED chip wafer, and the flip-chip Mini LED chip wafer includes a substrate and a plurality of chip layers arranged at intervals on the substrate;

[0106] (2) Set a first buffer film on the side of the substrate away from the chip layer. The first buffer film includes a substrate layer and a UV adhesive layer; subsequently, through the first buffer film, the substrate is cut by laser scribing to form a splitting point, and the cutting position corresponds to the interval between adjacent chip layers; then, at the corresponding position of the splitting point, the first buffer film is cut, and the cutting channel penetrates the first buffer film; finally, a first blue film is set on the first buffer film, and the cut flip-chip Mini LED chip wafer is split to obtain single flip-chip Mini LED chips;

[0107] Among them, in the first buffer film, the thickness of the substrate layer is 20μm, and the thickness of the UV adhesive layer is 5μm;

[0108] (3) Perform spot measurement testing;

[0109] (4) Set a second buffer film on the chip layer. The second buffer film includes a substrate layer and a UV adhesive layer; subsequently, the second buffer film is cut, and the cutting position corresponds to the interval between adjacent chip layers; and the film is expanded to make the distance between adjacent single flip-chip Mini LED chips reach a preset distance;

[0110] Among them, in the second buffer film, the thickness of the substrate layer is 20μm, and the thickness of the UV adhesive layer is 5μm.

[0111] (5) Use a sorting device to test the single flip-chip Mini LED chips, and classify them according to the Bin table according to the test results; then, align the top needle with the surface of the first blue film of the flip-chip Mini LED chip to be transferred, and align the suction nozzle with the surface of the second buffer film layer, and transfer the single flip-chip Mini LED chips of the same type to the same second blue film and arrange them at intervals on the second blue film;

[0112] (6) Set a third blue film on the second buffer film, and irradiate with UV light to remove the first buffer layer and the second blue film, exposing the substrate.

[0113] Correspondingly, this embodiment also provides a Mini LED device, and its manufacturing method includes:

[0114] (1) Transfer and die-bond the flip-chip Mini LED chip onto a substrate;

[0115] (2) Package the flip-chip Mini LED chip on the substrate.

[0116] Embodiment 2

[0117] This embodiment provides a flip-chip Mini LED chip, and its manufacturing method is basically the same as that of Embodiment 1, except that:

[0118] In step (2), in the first buffer film, the thickness of the substrate layer is 20 μm, and the thickness of the UV adhesion layer is 10 μm;

[0119] In step (4), in the second buffer film, the thickness of the substrate layer is 20 μm, and the thickness of the UV adhesion layer is 5 μm.

[0120] Correspondingly, this embodiment also provides a Mini LED device, which is prepared by using the manufacturing method in Embodiment 1.

[0121] Embodiment 3

[0122] This embodiment provides a flip-chip Mini LED chip, and its manufacturing method is basically the same as that of Embodiment 2, except that:

[0123] In step (2), in the first buffer film, the thickness of the substrate layer is 40 μm, and the thickness of the UV adhesion layer is 5 μm;

[0124] In step (4), in the second buffer film, the thickness of the substrate layer is 20 μm, and the thickness of the UV adhesion layer is 5 μm.

[0125] Correspondingly, this embodiment also provides a Mini LED device, which is prepared by using the manufacturing method in Embodiment 1.

[0126] Embodiment 4

[0127] This embodiment provides a flip-chip Mini LED chip, and its manufacturing method is basically the same as that of Embodiment 3, except that:

[0128] In step (2), in the first buffer film, the thickness of the substrate layer is 20 μm, and the thickness of the UV adhesion layer is 5 μm;

[0129] In step (4), in the second buffer film, the thickness of the substrate layer is 40 μm, and the thickness of the UV adhesion layer is 5 μm.

[0130] Correspondingly, this embodiment also provides a Mini LED device, which is prepared by using the preparation method in Embodiment 1.

[0131] Embodiment 5

[0132] This embodiment provides a flip-chip Mini LED chip, and its preparation method is basically the same as that in Embodiment 4, except that:

[0133] In step (2), in the first buffer film, the thickness of the substrate layer is 20 μm, and the thickness of the UV adhesion layer is 5 μm;

[0134] In step (4), in the second buffer film, the thickness of the substrate layer is 40 μm, and the thickness of the UV adhesion layer is 10 μm.

[0135] Control group

[0136] This comparative example provides a flip-chip Mini LED chip, which is basically the same as Embodiment 1, except that in step (2), the first buffer film is not provided; in step (4), the second buffer film is not provided.

[0137] Performance test

[0138] Select 500,000 flip-chip Mini LED chips obtained in the embodiments and comparative examples, and test their breakage rate and the accuracy of sorting and classification. The test results are shown in Table 1 below.

[0139] Table 1 Performance test results of the embodiments and comparative examples

[0140] Breakage rate Accuracy of sorting and classification Example 1 0.11％ 99.7％ Example 2 0.09％ 99.1％ Example 3 0.05％ 99.5％ Example 4 0.03％ 99.5％ Example 5 0.02％ 99.5％ Control group 0.4％ 99.8％

[0141] As can be seen from the above results, setting the first buffer film on the substrate and the second buffer film on the chip layer plays a protective role for the chip layer during spot testing, sorting, and subsequent die bonding operations, avoiding the failure of the flip-chip Mini LED chip due to the rigid action of the ejector pin, improving the yield, further extending the service life of the chip, and also maintaining the high accuracy of the flip-chip Mini LED chip during sorting and classification.

[0142] The above-disclosed is only a preferred embodiment of the present invention. Of course, it cannot be used to limit the scope of the rights of the present invention. Therefore, equivalent changes made according to the claims of the present invention still fall within the scope covered by the present invention.

Claims

1. A method for preparing a flip-chip Mini LED chip, characterized in that: include: A flip-chip Mini LED chip wafer is provided, wherein the flip-chip Mini LED chip wafer comprises a substrate and a plurality of chip layers spaced apart on the substrate; A first buffer film is disposed on a side of the substrate away from the chip layer, a first blue film is disposed on the first buffer film, and the substrate and the first buffer film are cut to obtain a single flip-chip Mini LED chip, where the cutting position corresponds to the interval between adjacent chip layers; Conduct spot test; A second buffer film is provided on the chip layer, and the second buffer film is cut, with the cutting position corresponding to the interval between adjacent chip layers; and the film is expanded so that a preset distance is reached between adjacent single flip-chip Mini LED chips; Sorting is performed to sort the single flip-chip Mini LED chips onto different second blue films; A third blue film is arranged on the second buffer film, and the first buffer film and the second blue film are removed by UV light irradiation to expose the substrate; Wherein, the first buffer film and the second buffer film both include a substrate layer and a UV adhesive layer.

2. The method for preparing a flip-chip Mini LED chip according to claim 1, characterized in that: Sorting, sorting single flip-chip Mini LED chips onto different second blue films includes: Use sorting equipment to test individual flip-chip Mini LED chips and classify them according to the test results; Align the top needle with the first blue film surface of the flip-chip Mini LED chip to be transferred, and align the suction nozzle with the surface of the second buffer film layer, transfer the same type of single flip-chip Mini LED chip to the same second blue film, and arrange them at intervals on the second blue film.

3. The method for preparing a flip-chip Mini LED chip according to claim 1, wherein: Cutting the substrate and the first buffer film to obtain a single flip-chip Mini LED chip includes: Through the first buffer film, the substrate is cut by laser hidden cutting to form a cleavage point, and the cutting position corresponds to the interval between adjacent chip layers; Cutting the first buffer film at a position corresponding to the cleavage point, wherein the cutting path penetrates the first buffer film; The cut flip-chip Mini LED chip wafer is split to obtain a single flip-chip Mini LED chip.

4. The method for preparing a flip-chip Mini LED chip according to claim 1, wherein: A first buffer film is arranged on a side of the substrate away from the chip layer, and the UV adhesive layer is bonded to the substrate; A second buffer film is arranged on the chip layer, and the UV adhesive layer is bonded to the chip layer; The thickness of the substrate layer is 10 μm-100 μm, the thickness of the UV adhesive layer is 3 μm-30 μm, and the substrate layer is a transparent insulating layer.

5. The method for preparing a flip-chip Mini LED chip according to claim 1, wherein: The thickness of the first buffer film is 13 μm-130 μm, and the thickness of the substrate is 60 μm-200 μm.

6. The method for preparing a flip-chip Mini LED chip according to claim 1, wherein: The thickness of the second buffer film is 13 μm-130 μm, the thickness of the chip layer is 5 μm-15 μm, and the width of the second buffer film is greater than the width of the chip layer on a single flip-chip Mini LED chip.

7. The method for preparing a flip-chip Mini LED chip according to claim 1, wherein: The chip layer includes an epitaxial layer, a current blocking layer and a transparent conductive layer which are arranged in sequence, the transparent conductive layer covers the current blocking layer, a P-type electrode and a groove extending to the epitaxial layer are arranged on the transparent conductive layer, an N-type electrode is arranged in the groove, a passivation layer and a pad are arranged on the transparent conductive layer, the passivation layer covers the P-type electrode and the groove, and the pad penetrates the passivation layer and is electrically connected to the P-type electrode and the N-type electrode.

8. A flip-chip Mini LED chip, characterized in that: The flip-chip Mini LED chip is prepared according to the method for preparing the flip-chip Mini LED chip according to any one of claims 1 to 7.

9. A Mini LED device, characterized in that: Comprising the flip-chip Mini LED chip as described in claim 8.

10. A method for preparing a Mini LED device according to claim 9, characterized in that: include: Transfer and bond the flip-chip Mini LED chip onto the substrate; The flip-chip Mini LED chip is packaged on a substrate.

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