Mass transfer method, temporary substrate, transfer substrate and LED display device

Abstract

The present invention relates to a mass transfer method, a temporary substrate, a transfer substrate and an LED display device. The mass transfer method includes arranging a plurality of first grooves on a temporary substrate, forming a first boss between any two adjacent first grooves, and arranging a first adhesive layer on the first boss; transferring an LED chip on a growth substrate to the temporary substrate so that the LED chip is bonded to the first adhesive layer; using a second adhesive layer on the transfer substrate to bond to a side of the LED chip away from the temporary substrate, heating the first adhesive layer to melt it and flow it into the first groove, so as to transfer the LED chip to the transfer substrate; transferring the LED chip on the transfer substrate to a display backplane. The first adhesive layer melts and flows into the first groove to prevent it from remaining on the electrode surface of the LED chip, and to prevent the vaporized adhesive from causing the LED chip to deviate or flip, thereby ensuring that the LED chip and the pad group are accurately aligned and improving the transfer efficiency.

Description

Technical Field

[0001] The invention relates to the field of display, and in particular to a mass transfer method, a temporary substrate, a transfer substrate and an LED display device. Background Art

[0002] At present, Micro Light-emitting Diode (Micro LED) display panel, as a new generation of display technology, has the advantages of higher brightness, better luminous efficiency and lower power consumption, making Micro LED widely used.

[0003] Micro LED display panels generally include multiple pixel areas, each of which includes a red LED chip, a blue LED chip, and a green LED chip. During the display panel preparation process, the three chips need to be transferred from their respective growth substrates to the display backplane. The above transfer method is mainly based on laser peeling of LED chips. However, this transfer method easily leaves residual glue on the LED chip. In addition, the glue is easily vaporized after being affected by high temperature, and the gas after the glue vaporizes causes the LED chip to shift or flip, affecting the transfer quality. Summary of the invention

[0004] In view of the above-mentioned deficiencies in the prior art, the purpose of the present application is to provide a mass transfer method, a temporary substrate, a transfer substrate and an LED display device, aiming to solve the problem that the glue is likely to remain on the LED chip when transferring the LED chip, and to solve the problem that the vaporized glue is likely to cause the LED chip to shift or flip.

[0005] The first aspect of the present application provides a mass transfer method, including: setting a plurality of first grooves on a temporary substrate so that a first boss is formed between any two adjacent first grooves, and then setting a first adhesive layer on the first boss; transferring an LED chip on a growth substrate to the temporary substrate so that the LED chip is bonded to the first adhesive layer; using a second adhesive layer on a transfer substrate to bond the side of the LED chip away from the temporary substrate, and then heating the first adhesive layer so that the first adhesive layer melts and at least partially flows into the first groove, so as to transfer the LED chip to the transfer substrate; transferring the LED chip on the transfer substrate to a display back panel.

[0006] In the above-mentioned mass transfer method, since a first groove is provided on the temporary substrate, when the LED chip on the temporary substrate is transferred to the transfer substrate, the first adhesive layer can partially or completely flow into the first groove after melting, thereby preventing the first adhesive layer from remaining on the electrode surface of the LED chip, and also preventing the LED chip from shifting or flipping after the first adhesive layer vaporizes, thereby ensuring that the electrode surface of the LED chip and the pad group are accurately aligned, thereby improving the transfer efficiency.

[0007] In some embodiments, the LED chip on the growth substrate is transferred to the temporary substrate so that the LED chip is bonded to the first adhesive layer, including: transferring the LED chip on the growth substrate to the temporary substrate so that the LED chip is bonded to the first adhesive layer, so that the LED chip covers a plurality of the first grooves, so that at least one of the first grooves covered by the LED chip is located below the positive electrode or the negative electrode of the LED chip.

[0008] In some embodiments, a plurality of first grooves are provided on the temporary substrate, specifically including: a plurality of first grooves having linear or ring-shaped extension paths are provided on the temporary substrate.

[0009] In some embodiments, a plurality of first grooves are provided on the temporary substrate, specifically comprising: a plurality of first grooves with a depth greater than 10 microns are provided on the temporary substrate. Thus, the first grooves have a sufficient depth, thereby providing sufficient accommodation space to accommodate the melted first adhesive layer.

[0010] In some embodiments, a plurality of first grooves are provided on the temporary substrate, specifically including: a plurality of first grooves having a width less than 1 micron are provided on the temporary substrate. Thus, the first grooves have a sufficient width, thereby providing sufficient accommodation space to accommodate the melted first adhesive layer. In addition, the first grooves of this width do not affect the contact between the LED chip and the temporary substrate.

[0011] In some embodiments, a first adhesive layer is provided on the first boss, specifically comprising: coating an adhesive material on the surface of the temporary substrate where the first groove is provided, and then removing the adhesive material in the first groove so that the adhesive material remaining on the first boss forms the first adhesive layer.

[0012] In some embodiments, before the second adhesive layer on the transfer substrate is bonded to the side of the LED chip away from the temporary substrate, the mass transfer method further includes: arranging a plurality of second grooves on the transfer substrate so that a second boss is formed between any two adjacent second grooves, and then arranging a second adhesive layer on the second boss; transferring the LED chip on the transfer substrate to the display backplane, specifically including: contacting the LED chip on the transfer substrate with the display backplane, and then heating the second adhesive layer so that the second adhesive layer melts and at least partially flows into the second groove, so as to transfer the LED chip to the display backplane. In the mass transfer method provided by this embodiment, since the second groove is arranged on the transfer substrate, when the LED chip on the transfer substrate is transferred to the display backplane, the second adhesive layer melts and can partially or completely flow into the second groove, thereby preventing the second adhesive layer from remaining on the light emitting surface of the LED chip, so as to improve the light emitting rate and light emitting uniformity of the LED chip, and also preventing the second adhesive layer from vaporizing and causing the LED chip to shift or flip, so as to ensure that the electrode surface of the LED chip and the pad group are accurately aligned, thereby improving the transfer efficiency.

[0013] In some embodiments, a plurality of second grooves are provided on the transfer substrate, specifically comprising: a plurality of second grooves with a depth greater than 10 microns are provided on the transfer substrate. Thus, the second grooves have a sufficient depth, thereby providing sufficient accommodation space to accommodate the melted second adhesive layer.

[0014] In some embodiments, a plurality of second grooves are provided on the transfer substrate, specifically comprising: a plurality of second grooves having a width less than 1 micron are provided on the transfer substrate. Thus, the second grooves have a sufficient width, thereby providing sufficient accommodation space to accommodate the melted second adhesive layer. In addition, the second grooves of this width do not affect the contact between the LED chip and the transfer substrate.

[0015] In some embodiments, before transferring the LED chips on the growth substrate to the temporary substrate, the mass transfer method further includes: detecting the bad LED chips on the growth substrate; transferring the LED chips on the growth substrate to the temporary substrate, specifically including: transferring at least some of the LED chips on the growth substrate except the bad LED chips to the temporary substrate. In this way, the bad LED chips on the growth substrate can be known, so that when transferring the LED chips to the transfer substrate, the bad LED chips can be avoided, ensuring that the LED chips transferred to the display backplane have a better appearance and better wavelength consistency.

[0016] In some embodiments, after the LED chips on the transfer substrate are transferred to the display backplane, the mass transfer method further includes: adding another LED chip to the corresponding position of the bad LED chip on the display backplane. In this way, the pad group corresponding to the bad LED chip can be prevented from being vacant, so that the pixels on the LED display device finally prepared are relatively complete, thereby improving the display effect.

[0017] The second aspect of the present application provides a temporary substrate, which is used in any of the mass transfer methods described in the first aspect of the present application, wherein a plurality of first grooves are provided on the temporary substrate, and a first boss is formed between any two adjacent first grooves, and a first adhesive layer is provided on the first boss. When the temporary substrate is used in the mass transfer method, the melted adhesive material will flow into the first grooves during the transfer process, and no adhesive material will remain on the transferred LED chip, which can prevent the first adhesive layer from remaining on the electrode surface of the LED chip, and can also prevent the LED chip from shifting or flipping after the first adhesive layer is vaporized, thereby ensuring that the electrode surface of the LED chip and the pad group are accurately aligned, thereby improving the transfer efficiency.

[0018] A third aspect of the present application provides a transfer substrate, which is applied to the mass transfer method described in any one of the first aspects of the present application, wherein a plurality of second grooves are arranged on the transfer substrate, a second boss is formed between any two adjacent second grooves, and a second adhesive layer is arranged on the second boss.

[0019] The fourth aspect of the present application provides an LED display device, comprising a display backplane and a plurality of LED chips, wherein the plurality of LED chips are transferred to the display backplane by the mass transfer method described in any one of the first aspects of the present application. The above-mentioned LED light-emitting device is prepared by using the above-mentioned mass transfer method, so that there is almost no glue residue on the LED chip of the finally prepared LED light-emitting device, so the connection stability of the LED chip is strong, and the quality of the LED light-emitting device is guaranteed. BRIEF DESCRIPTION OF THE DRAWINGS

[0020] Figure 1 It is a schematic diagram of the structure of a growth substrate provided by the prior art.

[0021] Figure 2 It is a structural schematic diagram of a growth substrate from another perspective provided by the prior art.

[0022] Figure 3 It is a schematic diagram of the structure in which a temporary substrate provided by the prior art is bonded to a growth substrate.

[0023] Figure 4 It is a schematic diagram of the structure of the process of transferring LED chips from a temporary substrate to a growth substrate provided by the prior art.

[0024] Figure 5 It is a structural schematic diagram of a temporary substrate with LED chips transferred provided by the prior art.

[0025] Figure 6 It is a structural schematic diagram of another perspective of transferring LED chips on a temporary substrate provided by the prior art.

[0026] Figure 7 It is a structural schematic diagram of transferring LED chips to a display backplane on a transfer substrate provided by the prior art.

[0027] Figure 8 It is a schematic diagram of the structure of a display back panel with LED chips transferred provided by the prior art.

[0028] Fig. 9 This is a flow chart of a mass transfer method provided by an embodiment of the present application.

[0029] Figures 10 to 18 It is a process flow diagram of a mass transfer method provided in one embodiment of the present application.

[0030] Fig.19 This is a flow chart of a mass transfer method provided by another embodiment of the present application.

[0031] Figure 20 to Figure 23 It is a process flow diagram of a mass transfer method provided in another embodiment of the present application.

[0032] Fig.24 This is a flow chart of a mass transfer method provided by yet another embodiment of the present application.

[0033] Fig.25 This is a flow chart of a mass transfer method provided in yet another embodiment of the present application.

[0034] Figure 26 to Figure 31 This is a process flow diagram of a mass transfer method provided in yet another embodiment of the present application.

[0035] Fig.32 This is a flow chart of a mass transfer method provided by yet another embodiment of the present application.

[0036] Figures 33 to 40 This is a schematic diagram of the process flow of a mass transfer method provided in yet another embodiment of the present application.

[0037] Explanation of the reference numerals: Prior art: 10 - growth substrate, 20 - LED chip, 30 - temporary substrate, 40 - transfer substrate, 50 - display backplane.

[0038] The present application: 100 - growth substrate, 200 - LED chip, 200a - bad point LED chip, 300 - temporary substrate, 310 - first groove, 320 - first boss, 330 - first adhesive layer, 400 - transfer substrate, 410 - second groove, 420 - second boss, 430 - second adhesive layer, 500 - display backplane. DETAILED DESCRIPTION

[0039] In order to facilitate the understanding of the present application, the present application will be described more fully below with reference to the relevant drawings. The preferred embodiments of the present application are given in the drawings. However, the present application can be implemented in many different forms and is not limited to the embodiments described herein. On the contrary, the purpose of providing these embodiments is to make the disclosure of the present application more thoroughly and comprehensively understood.

[0040] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as those commonly understood by those skilled in the art to which this application belongs. The terms used herein in the specification of this application are only for the purpose of describing specific embodiments and are not intended to limit this application.

[0041] For details, please refer to Figures 1 to 6 ,visible, Figure 1 It is a schematic diagram of the structure of a growth substrate provided by the prior art; Figure 2 is a schematic structural diagram of a growth substrate from another perspective provided in an embodiment of the present application; Figure 3 It is a schematic diagram of the structure in which a temporary substrate provided in an embodiment of the present application is bonded to a growth substrate; Figure 4 This is a schematic diagram of the process of transferring an LED chip from a temporary substrate to a growth substrate provided in an embodiment of the present application; Figure 5 This is a schematic diagram of the structure of a temporary substrate with an LED chip transferred thereon provided in an embodiment of the present application; Figure 6 This is a structural schematic diagram of another perspective of transferring an LED chip on a temporary substrate provided in an embodiment of the present application.

[0042] Generally, when the LED chip 20 is transferred to the display backplane 50, three colors of Micro LED chips are transferred. For the convenience of description, the red LED chip, blue LED chip and green LED chip are transferred separately. The following takes one LED chip 20 as an example for explanation. The same principle applies to the other two LED chips, which will not be repeated in this application.

[0043] The LED chip 20 is transferred to the display back panel 50 , and the specific process is as follows.

[0044] Step S10: Provide a growth substrate 10 (wafer), on which an LED chip 20 is grown. Then, the LED chip 20 is bonded to the temporary substrate 30 using the adhesive material on the temporary substrate 30. Then, the growth substrate 10 on the LED chip 20 is peeled off. Thus, the LED chip 20 can be transferred to the temporary substrate 30.

[0045] Step S11: selectively bond the LED chip 20 to the transfer substrate 40 using the adhesive material on the transfer substrate 40; Figure 7 , Figure 7 The transfer substrate 40 is shown to selectively bond the LED chip 20 on the temporary substrate 30 .

[0046] Step S12: Transfer the LED chip 20 on the transfer substrate 40 to the display backplane 50. Figure 8 , Figure 8 4 shows a schematic diagram of a successful transfer of the LED chip 20 onto the display backplane 50. The process of transferring the LED chip 20 from the transfer substrate 40 to the display backplane 50 is also a mass welding process. Therefore, after the transfer is completed, the LED chip 20 has completed the gold-indium eutectic bonding.

[0047] During the mass transfer process, the adhesive glue on the temporary substrate 30 is likely to remain on the electrode surface of the LED chip, and the residual glue may cause the electrode surface of the LED chip to not be in good contact with the pad group. In addition, the residual glue may also vaporize at high temperature, causing the position of the LED chip to shift, resulting in the LED chip not being able to accurately align with the pad group, and in severe cases, causing the LED chip to flip, resulting in low transfer efficiency.

[0048] It is understandable that LED chips generally include positive electrodes and negative electrodes. The display backplane is generally provided with a positive electrode pad group corresponding to the positive electrode, and a negative electrode pad group corresponding to the negative electrode. After the LED chip is transferred to the display backplane, the positive electrode of the LED chip needs to be electrically connected to the positive electrode pad group, and the negative electrode needs to be electrically connected to the negative electrode pad group, so that the LED chip can work smoothly. However, if the glue remains on the electrode surface of the LED chip, it is easy to cause the positive electrode to be unable to be electrically connected to the positive electrode pad group, or the negative electrode to be unable to be electrically connected to the negative electrode pad group. If the LED chip is flipped due to the vaporization of the glue, after the LED chip is transferred, its positive electrode is located on the side away from the positive electrode pad group, and the negative electrode is located on the side away from the negative electrode pad group, which directly causes the positive electrode to be unable to contact the positive electrode pad group, and the negative electrode to be unable to contact the negative electrode pad group, let alone electrical connection.

[0049] In order to solve the above problems, a mass transfer method provided in the embodiment of the present application is referred to Fig. 9 , the mass transfer method specifically includes the following steps.

[0050] Step S100: Reference Fig.10 and Fig.11 , a plurality of first grooves 310 are arranged on the temporary substrate 300 , so that a first boss 320 is formed between any two adjacent first grooves 310 , and then a first adhesive layer 330 is arranged on the first boss 320 .

[0051] refer to Fig.12 The specific process of forming the first adhesive layer 330 is as follows: coating the surface of the temporary substrate 300 with the first groove 310 with adhesive material, and then removing the adhesive material in the first groove 310, so that the adhesive material remaining on the first boss 320 forms the first adhesive layer 330. In detail, the temporary substrate 300 having the first groove 310 and the first adhesive layer 330 can be prepared by combining a mask method and plasma. More specifically, a plurality of first grooves 310 are processed on the temporary substrate 300 by a mask method, and then the adhesive material in the first groove 310 is cleaned by a plasma method.

[0052] It is understandable that the first adhesive layer 330 can be made of a low melting point adhesive material, and specifically, can be made of a polyurethane hot melt adhesive material.

[0053] It can also be understood that the temporary substrate 300 is generally in the shape of a thin plate, such as a circle, a rectangle or a square. It includes two surfaces arranged opposite to each other, wherein the first groove 310 can be arranged on any one of the surfaces. Taking the temporary substrate 300 as an example, a plurality of first grooves 310 with linear extension paths can be arranged on the temporary substrate 300. At this time, the plurality of first grooves 310 are arranged in parallel with each other and all extend along the length direction of the temporary substrate 300, or extend along the width direction of the temporary substrate 300, or extend along an angle of about 40 degrees with the length direction, thereby making the guide route of the first adhesive layer 330 melted after heating longer, and increasing the discharge efficiency of the first adhesive layer 330 melted after heating.

[0054] Of course, in some other embodiments, a first annular groove 310 is provided on the temporary substrate 300, and the first annular groove 310 surrounds a circular first boss 320. Thus, each first boss 320 is surrounded by an annular first groove 310, and the melted first adhesive layer 330 can be better guided. In addition, the supporting surface of the first boss 320 surrounded by the first groove 310 of this structure is larger. When the LED chip 200 is bonded to the first boss 320, the bonding reliability of the LED chip 200 is better, and the transfer efficiency can be improved.

[0055] A first boss 320 may be surrounded by one circle of first grooves 310, or may be surrounded by two, three, four, etc. circles of first grooves 310, wherein there is a gap between two adjacent first grooves 310. Then, after the LED chip 200 is transferred to the temporary substrate 300, the LED chip 200 may cover the first boss 320 and one circle of the first grooves 310, or may cover the first boss 320 and two, three, four, etc. circles of the first grooves 310, and at least one section of the first grooves 310 covered by the LED chip 200 is located between the positive electrode and the negative electrode of the LED chip 200, thereby allowing the first adhesive layer 330 to be better guided after melting to prevent the adhesive from adhering to the electrode surface of the LED chip.

[0056] That is, providing a plurality of first grooves 310 on the temporary substrate 300 may specifically include: providing a plurality of first grooves 310 having linear or ring-shaped extension paths on the temporary substrate 300 .

[0057] Step S110 : transferring the LED chip 200 on the growth substrate 100 to the temporary substrate 300 , so that the LED chip 200 is bonded to the first adhesive layer 330 .

[0058] Specifically, refer to Fig.13 and Fig.14 , the side of the growth substrate 100 having the LED chip 200 can be faced to the side of the temporary substrate 300 having the first adhesive layer 330, and the LED chip 200 can be made to contact the first adhesive layer 330, and then the LED chip 200 can be peeled off from the growth substrate 100 using a laser, thereby transferring the LED chip 200 to the temporary substrate 300. At this time, the LED chip 200 is bonded to the first adhesive layer 330.

[0059] Among them, in some embodiments, the LED chip 200 on the growth substrate 100 is transferred to the temporary substrate 300 so that the LED chip 200 is bonded to the first adhesive layer 330, which can specifically include: transferring the LED chip 200 on the growth substrate 100 to the temporary substrate 300, so that after the LED chip 200 is bonded to the first adhesive layer 330, the LED chip 200 covers at least one of the first grooves 310, and at least one of the first grooves 310 covered by the LED chip 200 is located between the positive electrode and the negative electrode of the LED chip 200.

[0060] That is, one LED chip 200 can be made to cover at least one first groove 310, so there is a first boss 320 on each side of the first groove 310. After the LED chip 200 is transferred to the temporary substrate 300, the positive electrode of the LED chip 200 is bonded to the first adhesive layer 330 on the first boss 320 on one side of the first groove 310, and the negative electrode of the LED chip 200 is bonded to the first adhesive layer 330 on the first boss 320 on the other side of the first groove 310. At this time, the first groove 310 covered by the LED chip 200 is located between the positive electrode and the negative electrode of the LED chip 200.

[0061] Then in the subsequent steps, after the first adhesive layer 330 on the two first bosses 320 connecting the positive electrode and the negative electrode of the LED chip 200 melts, it can flow into the first groove 310 located between the positive electrode and the negative electrode, thereby preventing the adhesive from remaining on the electrode surface of the LED chip 200.

[0062] Specifically, the width of the first boss 320 may be set to be between 10 microns and 14 microns, for example, the width of the first boss 320 may be 10 microns, 11 microns, 12 microns, 13 microns or 14 microns, etc. Generally, the width of an LED chip is about 27 microns, so setting the width of the first boss 320 to be between 10 microns and 14 microns allows one LED chip 200 to cover at least one first groove 310.

[0063] It is also possible to make one LED chip 200 correspondingly cover at least a plurality of first grooves 310, where the plurality means more than two. For example, making the LED chip 200 correspondingly cover two first grooves 310, wherein the two first grooves 310 are both located between the positive electrode and the negative electrode of the LED chip 200, or, wherein one of the first grooves 310 is located between the positive electrode and the negative electrode of the LED chip 200, and the other first groove 310 is located below the positive electrode or below the negative electrode.

[0064] For example, the LED chip 200 covers three first grooves 310, one of which is located between the positive electrode and the negative electrode of the LED chip, another is located below the positive electrode of the LED chip, and another is located below the negative electrode of the LED chip. Thus, the first adhesive layer 330 can be better guided after melting, preventing the adhesive from adhering to the electrode surface of the LED chip 200.

[0065] Of course, the positive electrode of an LED chip 200 may cover two or more first grooves 310, and the negative electrode thereof may cover two or more first grooves 310. Thus, after the first adhesive layer 330 melts, the adhesive corresponding to the positive electrode and the negative electrode may be guided along the first grooves 310 below them, thereby preventing the adhesive from remaining on the positive electrode and the negative electrode.

[0066] Step S120: Reference Fig.15 and Fig.16 , use the second adhesive layer 430 on the transfer substrate 400 to adhere to the side of the LED chip 200 away from the temporary substrate 300, and then heat the first adhesive layer 330 so that the first adhesive layer 330 melts and at least partially flows into the first groove 310, so as to transfer the LED chip 200 to the transfer substrate 400.

[0067] Specifically, a laser can be used to irradiate the side of the temporary substrate 300 away from the first adhesive layer 330, and then the heat is transferred to the first adhesive layer 330, so that the first adhesive layer 330 melts, and the melted liquid adhesive can flow into the first groove 310. At this time, the first adhesive layer 330 loses its adhesion to the LED chip 200, and the LED chip 200 is bonded by the second adhesive layer 430, thereby being transferred to the transfer substrate 400.

[0068] It is understandable that the second adhesive layer 430 can be made of the same material as the first adhesive layer 330. Then, when the laser irradiates the side of the temporary substrate 300 away from the first adhesive layer 330, there is an LED chip 200 between the first adhesive layer 330 and the second adhesive layer 430, and the heat is less or cannot be transferred to the second adhesive layer 430. As a result, the first adhesive layer 330 can be melted and lose its adhesion to the LED chip 200, and the first adhesive layer 330 and the second adhesive layer 430 can be prepared with the same material, thereby facilitating processing and reducing costs.

[0069] Of course, in other embodiments, the second adhesive layer 430 may be made of a material with slightly stronger adhesion than that of the second adhesive layer 430 and a slightly higher melting point than that of the first adhesive layer 330. Thus, the second adhesive layer 430 can be prevented from melting when the first adhesive layer 330 is heated, so that the second adhesive layer 430 can be better bonded to the LED chip 200 to improve the transfer efficiency.

[0070] Step S130 : transferring the LED chip 200 on the transfer substrate 400 to the display backplane 500 .

[0071] Specifically, refer to Fig.17 and Fig.18, the side of the transfer substrate 400 bonded with the LED chip 200 can face the display backplane 500, so that the LED chip 200 corresponds to the pad group on the display backplane 500, and then the transfer substrate 400 is irradiated with a laser away from the display backplane 500, so that the second adhesive layer 430 loses its adhesion to the LED chip 200. As a result, the LED chip 200 is detached from the transfer substrate 400 and transferred to the display backplane 500, and then the bonding of the LED chip 200 and the display backplane 500 is completed.

[0072] In the mass transfer method provided by the above-mentioned embodiment, since a first groove 310 is provided on the temporary substrate 300, when the LED chip 200 on the temporary substrate 300 is transferred to the transfer substrate 400, the first adhesive layer 330 can partially or completely flow into the first groove 310 after melting, thereby preventing the first adhesive layer 330 from remaining on the electrode surface of the LED chip 200, and also preventing the LED chip 200 from shifting or flipping after the first adhesive layer 330 vaporizes, thereby ensuring that the electrode surface of the LED chip 200 and the pad group are accurately aligned, thereby improving the transfer efficiency.

[0073] The present application embodiment also provides another mass transfer method, referring to Fig.19 , the mass transfer method provided in this embodiment includes the following steps.

[0074] Step S200: a plurality of first grooves 310 with a depth greater than 10 microns are provided on the temporary substrate 300, so that a first boss 320 is formed between any two adjacent first grooves 310, and then a first adhesive layer 330 is provided on the first boss 320. Specifically, the depth of the first groove 310 can be 11 microns, 12 microns, or 13 microns, etc.

[0075] In this embodiment, the depth of the first groove 310 is greater than 10 microns. It can be understood that the depth of the first groove 310 is a dimension extending along the thickness direction of the temporary substrate 300. Therefore, the first groove 310 has a sufficient depth, so as to provide sufficient accommodation space to accommodate the melted first adhesive layer 330.

[0076] It can be understood that the maximum depth of the first groove 310 can be two-thirds of the thickness of the temporary substrate 300 , thereby ensuring that the depth of the first groove 310 is deep enough and that the temporary substrate 300 has sufficient structural strength.

[0077] Step S210: Reference Fig. 20 and Fig.21, the LED chip 200 on the growth substrate 100 is transferred to the temporary substrate 300, so that the LED chip 200 is bonded to the first bonding adhesive layer 330. This step is the same as step S110 in the above embodiment and will not be described in detail.

[0078] Step S220: Reference Fig. 22 and Fig.23 , the second adhesive layer 430 on the transfer substrate 400 is bonded to the side of the LED chip 200 away from the temporary substrate 300, and then the first adhesive layer 330 is heated to melt the first adhesive layer 330 and at least partially flow into the first groove 310, so as to transfer the LED chip 200 to the transfer substrate 400. This step is the same as step S120 in the above embodiment and will not be described in detail.

[0079] Step S230: transferring the LED chip 200 on the transfer substrate 400 to the display backplane 500. This step is the same as step S130 in the above embodiment and will not be described in detail.

[0080] The present application embodiment also provides another mass transfer method, referring to Fig.24 The steps of the mass transfer method provided in this embodiment specifically include:

[0081] Step S300 : a plurality of first grooves 310 with a width less than 1 μm are arranged on the temporary substrate 300 , so that a first boss 320 is formed between any two adjacent first grooves 310 , and then a first adhesive layer 330 is arranged on the first boss 320 .

[0082] In this embodiment, the width of the first groove 310 is less than 1 micron. It can be understood that the width of the first groove 310 is a dimension extending along a thickness direction perpendicular to the temporary substrate 300. Thus, the first groove 310 has a sufficient width, so that sufficient accommodation space can be provided to accommodate the melted first adhesive layer 330. In addition, the first groove 310 of this width reserves enough space for the first boss 320, so that a larger area of ​​the first adhesive layer 330 can be set on the first boss 320, so that the first adhesive layer 330 can better support the LED chip, thereby preventing the LED chip from tipping over. The width of the first groove 310 can be 0.9 micron, 0.8 micron, 0.7 micron, etc.

[0083] Step S310: Transfer the LED chip 200 on the growth substrate 100 to the temporary substrate 300, so that the LED chip 200 is bonded to the first bonding adhesive layer 330. This step is the same as step S110 in the above embodiment, and will not be described in detail.

[0084] Step S320: Use the second adhesive layer 430 on the transfer substrate 400 to adhere to the side of the LED chip 200 away from the temporary substrate 300, and then heat the first adhesive layer 330 to melt the first adhesive layer 330 and at least partially flow into the first groove 310, so as to transfer the LED chip 200 to the transfer substrate 400. This step is the same as step S120 in the above embodiment and will not be repeated.

[0085] Step S330: transferring the LED chip 200 on the transfer substrate 400 to the display backplane 500. This step is the same as step S130 in the above embodiment and will not be described in detail.

[0086] The present application embodiment also provides another method for mass transfer, referring to Fig.25 The mass transfer method provided in this embodiment specifically includes the following steps.

[0087] Step S400: multiple first grooves 310 are provided on the temporary substrate 300, so that a first boss 320 is formed between any two adjacent first grooves 310, and then a first adhesive layer 330 is provided on the first boss 320. This step is the same as step S100 in the above embodiment and will not be described in detail.

[0088] Step S410: Transfer the LED chip 200 on the growth substrate 100 to the temporary substrate 300, so that the LED chip 200 is bonded to the first bonding adhesive layer 330. This step is the same as step S110 in the above embodiment and will not be described in detail.

[0089] Step S420: Reference Fig.26 A plurality of second grooves 410 are arranged on the transfer substrate 400 , so that a second boss 420 is formed between any two adjacent second grooves 410 , and then a second adhesive layer 430 is arranged on the second boss 420 .

[0090] Specifically, the specific process of forming the second adhesive layer 430 is as follows: coating the surface of the transfer substrate 400 with the second groove 410 with adhesive material, and then removing the adhesive material in the second groove 410, so that the adhesive material remaining on the second boss 420 forms the second adhesive layer 430. In detail, the transfer substrate 400 having the second groove 410 and the second adhesive layer 430 can be prepared by combining a mask method and a plasma method.

[0091] It is understandable that the second adhesive layer 430 can be made of a low melting point adhesive material, and specifically, can be made of a polyurethane hot melt adhesive material.

[0092] It can also be understood that the transfer substrate 400 is generally in the shape of a thin plate, such as a circle, a rectangle or a square. It includes two surfaces arranged opposite to each other, wherein the second groove 410 can be arranged on any of the surfaces. Taking the transfer substrate 400 as an example, a plurality of second grooves 410 with linear extension paths can be arranged on the transfer substrate 400. In this case, the plurality of second grooves 410 are arranged parallel to each other and all extend along the length direction of the transfer substrate 400, or extend along the width direction of the transfer substrate 400, or extend along an angle of about 40 degrees with the length direction, thereby making the guide path of the second adhesive layer 430 melted after heating longer, thereby increasing the discharge efficiency of the second adhesive layer 430 melted after heating.

[0093] Of course, in some other embodiments, a second annular groove 410 is provided on the transfer substrate 400, and the annular second groove 410 surrounds a circular second boss 420. Thus, each second boss 420 is surrounded by an annular second groove 410, and the melted second adhesive layer 430 can be better guided; in addition, the second boss 420 surrounded by the second groove 410 of this structure has a larger supporting surface, and when the LED chip 200 is bonded to the second boss 420, the bonding reliability of the LED chip 200 is better, which can improve the transfer efficiency.

[0094] That is, the plurality of second grooves 410 may be provided on the transfer substrate 400 , which may specifically include: a plurality of second grooves 410 with linear or annular extension paths are provided on the transfer substrate 400 .

[0095] In some more specific embodiments, the depth of the second groove 410 can be set to be greater than 10 microns. It can be understood that the depth of the second groove 410 is the dimension extending along the thickness direction of the transfer substrate 400. Therefore, the second groove 410 has a sufficient depth, so as to provide a sufficient accommodation space to accommodate the melted second adhesive layer 430. It can be understood that the depth of the second groove 410 can be at most two-thirds of the thickness of the transfer substrate 400, thereby making the depth of the second groove 410 deep enough and ensuring that the transfer substrate 400 has sufficient structural strength.

[0096] In some more specific embodiments, the width of the second groove 410 can be set to be less than 1 micron. It can be understood that the width of the second groove 410 is a dimension extending along a direction perpendicular to the thickness of the transfer substrate 400. Therefore, the second groove 410 has a sufficient width, so as to provide sufficient accommodation space to accommodate the melted second adhesive layer 430. In addition, the second groove 410 of this width does not affect the contact between the LED chip 200 and the transfer substrate 400.

[0097] Step S430: Reference Figure 27 to Figure 29 , the second adhesive layer 430 on the transfer substrate 400 is bonded to the side of the LED chip 200 away from the temporary substrate 300, and then the first adhesive layer 330 is heated to melt the first adhesive layer 330 and at least partially flow into the first groove 310, so as to transfer the LED chip 200 to the transfer substrate 400. This step is the same as step S120 in the above embodiment and will not be described in detail.

[0098] Step S440: Reference Fig.30 and Fig.31 , the LED chip 200 on the transfer substrate 400 is brought into contact with the display back panel 500, and then the second adhesive layer 430 is heated so that the second adhesive layer 430 melts and at least partially flows into the second groove 410, so as to transfer the LED chip 200 to the display back panel 500.

[0099] Specifically, a laser can be used to irradiate the side of the transfer substrate 400 away from the second adhesive layer 430, and then the heat is transferred to the second adhesive layer 430 to melt the second adhesive layer 430. The melted liquid adhesive can flow into the second groove 410. At this time, the second adhesive layer 430 loses its adhesion to the LED chip 200, and the LED chip 200 is transferred to the display back panel 500.

[0100] The mass transfer method provided in this embodiment has a second groove 410 provided on the transfer substrate 400. Therefore, when the LED chip 200 on the transfer substrate 400 is transferred to the display backplane 500, the second adhesive layer 430 can partially or completely flow into the second groove 410 after melting, thereby preventing the second adhesive layer 430 from remaining on the light emitting surface of the LED chip 200, so as to improve the light output rate and light uniformity of the LED chip 200. It can also prevent the LED chip 200 from being offset or flipped after the second adhesive layer 430 is vaporized, thereby ensuring that the electrode surface of the LED chip 200 and the pad group are accurately aligned, thereby improving the transfer efficiency.

[0101] The present application embodiment also provides another mass transfer method, referring to Fig.32 , the mass transfer method provided in this embodiment includes the following steps.

[0102] Step S500: multiple first grooves 310 are provided on the temporary substrate 300, so that a first boss 320 is formed between any two adjacent first grooves 310, and then a first adhesive layer 330 is provided on the first boss 320. This step is the same as step S100 in the above embodiment and will not be described in detail.

[0103] Step S510: Reference Fig.33 , detect the bad LED chip 200a on the growth substrate 100. Specifically, the optical characteristics and appearance quality of the LED chip 200 transferred to the temporary substrate 300 can be detected in advance by using Micro Automated Optical Inspection (AOI) or Micro Photoluminescence (PL) detection equipment, and the corresponding data mapping (Mapping Data) can be generated. In this way, the bad LED chip 200a on the growth substrate 100 can be known, so that when the LED chip is transferred to the temporary substrate 300, the bad LED chip 200a can be avoided, ensuring that the LED chip 200 transferred to the display backplane 500 has a good appearance and good wavelength consistency.

[0104] Step S520: Reference Fig.34 and Fig.35 , at least part of the LED chips 200 on the growth substrate 100 except for the bad LED chips 200a are transferred to the temporary substrate 300, so that the LED chips 200 are bonded to the first adhesive layer 330. Specifically, the laser irradiates the normal LED chips 200 in a targeted manner, avoiding the bad LED chips 200a, so that the normal LED chips 200 are peeled off from the growth substrate 100, thereby ensuring that the LED chips 200 transferred to the display backplane 500 are all LED chips 200 with normal appearance and good wavelength consistency, so that the final prepared LED display device has good light emission consistency.

[0105] Step S530: Reference Fig.36 and Fig.37 , use the second adhesive layer 430 on the transfer substrate 400 to adhere to the side of the LED chip 200 away from the temporary substrate 300, and then heat the first adhesive layer 330 corresponding to the LED chip 200, so that the first adhesive layer 330 melts and at least partially flows into the first groove 310, so as to transfer at least part of the LED chips 200 except the dead point LED chip 200a to the transfer substrate 400.

[0106] Step S540: Reference Fig.38 and Fig.39 , the LED chip 200 on the transfer substrate 400 is transferred to the display backplane 500. This step is the same as step S130 in the above embodiment, and will not be described in detail.

[0107] Understandably, reference Fig.40After the LED chips 200 on the transfer substrate 400 are transferred in batches to the display backplane 500, another LED chip 200 can be added to the pad group corresponding to the bad LED chip 200a. In this way, the pad group corresponding to the bad LED chip 200a can be prevented from being vacant, so that the pixels on the LED display device finally prepared are relatively complete, thereby improving the display effect.

[0108] The present application embodiment also provides a temporary substrate 300, referring to Figures 11 to 13 The temporary substrate 300 is applied to the mass transfer method described in any of the above embodiments. A plurality of first grooves 310 are provided on the temporary substrate 300. A first boss 320 is formed between any two adjacent first grooves 310. A first adhesive layer 330 is provided on the first boss 320. When the temporary substrate 300 is applied to the mass transfer method, the melted adhesive material will flow into the first groove 310 during the transfer process, and no adhesive material will remain on the transferred LED chip 200, which can prevent the first adhesive layer 330 from remaining on the electrode surface of the LED chip 200. It can also prevent the first adhesive layer 330 from vaporizing and causing the LED chip 200 to shift or flip, ensuring that the electrode surface of the LED chip 200 and the pad group are accurately aligned, thereby improving the transfer efficiency.

[0109] The present application embodiment also provides a transfer substrate 400, referring to Fig.26 , the temporary substrate 400 is applied to the mass transfer method described in any of the above embodiments, and a plurality of second grooves 410 are provided on the temporary substrate 400, and a second boss 420 is formed between any two adjacent second grooves 410, and a second adhesive layer 440 is provided on the second boss 420. When the temporary substrate 400 is applied to the mass transfer method, the melted adhesive material will flow into the second grooves 410 during the transfer process, and no adhesive material will remain on the transferred LED chip 200, which can prevent the second adhesive layer 440 from remaining on the light-emitting surface of the LED chip 200, and can also prevent the second adhesive layer 440 from vaporizing and causing the LED chip 200 to shift or flip, thereby ensuring that the electrode surface of the LED chip 200 and the pad group are accurately aligned, thereby improving the transfer efficiency.

[0110] Based on the mass transfer method provided in any of the above embodiments, another embodiment of the present application provides a display device, which specifically includes a display backplane and multiple LED chips, wherein the LED chips are transferred to the display backplane using the mass transfer method provided in any of the above embodiments.

[0111] It should be understood that the application of the present invention is not limited to the above examples. For ordinary technicians in this field, improvements or changes can be made based on the above description. All these improvements and changes should fall within the scope of protection of the claims attached to the present invention.

Claims

1. A mass transfer method, characterized in that: include: Arranging a plurality of first grooves on the temporary substrate so that a first boss is formed between any two adjacent first grooves, and then arranging a first adhesive layer on the first boss; Transferring the LED chip on the growth substrate to the temporary substrate, so that the LED chip is bonded to the first adhesive layer; wherein the LED chip covers a plurality of the first grooves, and at least one of the first grooves covered by the LED chip is located below the positive electrode or the negative electrode of the LED chip; Using the second adhesive layer on the transfer substrate to adhere to the side of the LED chip away from the temporary substrate, and then heating the first adhesive layer so that the first adhesive layer melts and at least partially flows into the first groove, so as to transfer the LED chip to the transfer substrate; The LED chip on the transfer substrate is transferred to the display backplane.

2. The method for mass transfer according to claim 1, characterized in that: At least one of the first grooves covered by the LED chip is located between the positive electrode and the negative electrode of the LED chip.

3. The mass transfer method according to claim 1 or 2, characterized in that: The provision of a plurality of first grooves on the temporary substrate specifically includes: provision of a plurality of first grooves with linear or ring-shaped extension paths on the temporary substrate.

4. The method for mass transfer according to claim 1 or 2, characterized in that: Providing a plurality of first grooves on the temporary substrate specifically includes: providing a plurality of first grooves with a depth greater than 10 micrometers on the temporary substrate; And / or, a plurality of first grooves are provided on the temporary substrate, specifically including: a plurality of first grooves with a width less than 1 micrometer are provided on the temporary substrate.

5. The method for mass transfer according to claim 1 or 2, characterized in that: Providing a first adhesive layer on the first boss specifically includes: coating an adhesive material on the surface of the temporary substrate provided with the first groove, and then removing the adhesive material in the first groove so that the adhesive material remaining on the first boss forms the first adhesive layer.

6. The method for mass transfer according to claim 1 or 2, characterized in that: Before the LED chip is bonded to the side of the temporary substrate by the second adhesive layer on the transfer substrate, the mass transfer method further comprises: arranging a plurality of second grooves on the transfer substrate so that a second boss is formed between any two adjacent second grooves, and then arranging a second adhesive layer on the second boss; Transferring the LED chip on the transfer substrate to the display backplane specifically includes: contacting the LED chip on the transfer substrate with the display backplane, and then heating the second adhesive layer so that the second adhesive layer melts and at least partially flows into the second groove, so as to transfer the LED chip to the display backplane.

7. The method for mass transfer according to claim 6, characterized in that: The step of providing a plurality of second grooves on the transfer substrate specifically includes: providing a plurality of second grooves with a depth greater than 10 micrometers on the transfer substrate; And / or, a plurality of second grooves are provided on the transfer substrate, specifically including: a plurality of second grooves with a width less than 1 micrometer are provided on the transfer substrate.

8. A temporary substrate, the temporary substrate being used in the mass transfer method according to any one of claims 1 to 7, characterized in that: A plurality of LED chips are pasted on the temporary substrate, a plurality of first grooves are arranged on the temporary substrate, a first boss is formed between any two adjacent first grooves, a first adhesive layer is arranged on the first boss, and the plurality of LED chips are pasted on the first boss through the first adhesive layer.

9. A transfer substrate, the transfer substrate being applied to the mass transfer method according to any one of claims 1 to 7, characterized in that: A plurality of LED chips are pasted on the transfer substrate, a plurality of second grooves are arranged on the transfer substrate, a second boss is formed between any two adjacent second grooves, a second adhesive layer is arranged on the second boss, and the plurality of LED chips are pasted on the second boss through the second adhesive layer.

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