Mass transfer method for Micro-LED

Abstract

The invention discloses a mass transfer method for a Micro-LED, and the method comprises the steps: enabling a bonding layer formed by a polyamide composition to serve as a protection layer of the Micro-LED, carrying out the protection of a Micro-LED chip, carrying out the pressing of the Micro-LED chip with another transparent substrate, and carrying out the laser irradiation of the bonding layer formed by the polyamide composition, so as to release the transferred Micro-LED chip. According to the invention, the breakage of the Micro-LED chip can be effectively avoided, and the yield of mass transfer of the Micro-LED is improved. The polyamide composition provided by the invention has low glass transition temperature and high absorption characteristic, so that the polyamide composition can be used as a low-temperature bonding material of a Micro-LED and a transfer material of laser dissociation, and the yield of mass transfer in a double-layer structure can be improved.

Description

Technical Field

[0001] The present application relates to a manufacturing method of semiconductor devices, and particularly to a mass transfer method for Micro-LEDs. Background Art

[0002] As Figure 1 shown, the existing mass transfer adopts a double-layer structure. First, a laser sacrificial layer 3 is coated on a transparent substrate 4, then a bonding adhesive layer 2 is coated, and finally a wafer 1 (or Micro-LED chip) is directly pressed by vacuum lamination; in the double-layer structure, for the double-layer structure, if the yield of single-layer laser dissociation and degumming is 90%, the yield of the double-layer structure is only 81%. Therefore, increasing the layer structure will reduce the mass transfer yield. Summary of the Invention

[0003] In view of this, the present application provides a mass transfer method for Micro-LEDs. After protecting the Micro-LED chip with a bonding layer formed by a polyamide composition as a protective layer of the Micro-LED, it is pressed with another transparent substrate, and then the bonding layer formed by the polyamide composition is irradiated with a laser to release the transferred Micro-LED chip; the specific scheme adopted is as follows:

[0004] A mass transfer method for Micro-LEDs includes the following steps:

[0005] S1. Provide a first substrate with Micro-LED chips;

[0006] S2. Coat a bonding layer with a polyamide composition on the first substrate. The bonding layer covers the first substrate and coats the Micro-LED chips; the thickness of the bonding layer is greater than the thickness of the Micro-LED chips; and the bonding layer is cured;

[0007] S3. From the side away from the first substrate, bond a second substrate to the cured and formed bonding layer by vacuum lamination. The second substrate is a transparent substrate;

[0008] S4. Dissociate and release the Micro-LED chips from the first substrate with a laser, and separate the second substrate from the first substrate; the Micro-LED chips are transferred to the second substrate through the bonding layer;

[0009] S5. Then dissociate and release the Micro-LED chips from the second substrate with a laser and transfer them to a TFT substrate or a circuit board with circuits.

[0010] The content of polyamide in the polyamide composition is 10 - 70 wt%, and the rest are solvents and additives; preferably, the content of polyamide in the polyamide composition is 15 wt - 50 wt%; the polyamide is a copolymer of diester and diamine, having the structure shown in formula (I):

[0011]

[0012] n is an integer from 1 to 200; preferably, n is an integer from 5 - 150; more preferably, n is an integer from 5 - 50; R1, R2, and R3 are each independently selected from at least one of C6 - 14 aryl, alkyl, aralkyl, alkoxy, hydroxyl, siloxanyl, polyethylene glycol group, polypropylene glycol group, heteroaryl, 5 - or 6 - membered nitrogen - containing heterocyclic group.

[0013] In some embodiments, in step S4, after transferring the Micro - LED chip to the second substrate, it further includes the steps of cleaning the second substrate with the Micro - LED chip and removing the residual glue.

[0014] In some embodiments, repeating steps S3 and S4 can arrange the three primary colors or different chip pitches.

[0015] In some embodiments, R1, R2, and R3 are each independently selected from the following groups:

[0016]

[0017] 5 - or 6 - membered nitrogen - containing heterocyclic group;

[0018] n1 - n8 are integers from 1 to 100; X is O, S, or the following divalent group:

[0020]

[0021] A and B are each independently selected from one of O, S, and CH2 groups.

[0022] In some embodiments, the glass transition temperature Tg of the polyamide is 30 - 250 °C; preferably, the glass transition temperature of the polyamide is 100 - 200 °C.

[0023] In some embodiments, the thickness of the bonding layer is 1.01 - 100 times the thickness of the Mico - LED chip; preferably, the thickness of the bonding layer is 1.01 - 10 times the thickness of the Mico - LED chip.

[0024] In some embodiments, the diester or diamine monomer can be one or a mixture of more than one monomer.

[0025] In some embodiments, the energy released by the laser in steps S4 and S5 is 100 - 2000 J / cm 2 , or the energy released by the laser in steps S4 and S5 is 300 - 1000 J / cm 2 .

[0026] Advantages of the present application:

[0027] 1) Compared with the existing method: directly pressing the Micro-LED on the carrier containing transfer glue without protecting the Micro-LED; in the present application, the bonding layer with the polyamide composition is thicker than the thickness of the Micro-LED chip. After protecting the Mico-LED with the bonding layer having the polyamide composition first and then pressing it with another transparent substrate, the rupture of the Micro-LED chip can be effectively avoided, and the yield of the massive transfer of Mirco-LED can be improved.

[0028] 2) The polyamide composition provided by the present application has a low glass transition temperature and high absorption characteristics, so it can be used both as a low-temperature bonding material for Micro-LED and a transfer material for laser dissociation, that is, it has both Figure 2 the functions of the laser sacrificial layer and the bonding adhesive layer in

[0029] . Belonging to a single-layer structure; compared with the double-layer structure, the single-layer structure can improve the yield of massive transfer. Description of the drawings

[0030] Figure 1 is a schematic diagram of the existing double-layer structure of massive transfer.

[0031] Figure 2 is a schematic diagram of the structure of Micro-LED transferred from the first substrate to the second substrate in the present application.

[0032] 1. Wafer, 2. Bonding adhesive layer, 3. Laser sacrificial layer, 4. Transparent substrate;

[0033] 5. First substrate, 6. Bonding layer, 7. Second substrate, 8. Micro-LED chip. Detailed implementation manners

[0034] To facilitate the understanding of the content described herein, several terms are defined below.

[0035] The term "about" means an acceptable error of a specific value as determined by a person of ordinary skill in the art, and the error range depends on how the value is measured or determined.

[0036] In the present application, the term "alkyl" refers to a saturated straight-chain or branched-chain hydrocarbon group, preferably having 1 to 14 carbon atoms, more preferably having 1 to 6 or 1 to 4 carbon atoms; examples thereof include (but are not limited to) methyl, ethyl, n-propyl, isopropyl, n-butyl, isobutyl, tert-butyl, pentyl, hexyl and similar groups.

[0037] In the present application, the term "polyether group" refers to a saturated straight-chain or branched-chain ether group, preferably an ethoxy group or a propoxy group having 1 to 20 repeating units, more preferably having 1 to 10 repeating units.

[0038] In the present application, the term "aryl" refers to an aromatic ring system having 6 to 14 carbon atoms, such as a 6-carbon monocyclic, 10-carbon bicyclic- or 14-carbon tricyclic aromatic ring system; examples of aryl include (but are not limited to) phenyl, tolyl, naphthyl, fluorenyl, anthracenyl, phenanthryl and similar groups.

[0039] In the present application, the term "alkoxy" refers to an alkyl group attached to an oxygen atom, preferably having 1 to 8 carbon atoms, more preferably having 1 to 4 carbon atoms.

[0040] In the present application, the term "heterocyclic group" refers to a saturated, partially saturated (such as named with prefixes such as dihydro, trihydro, tetrahydro, hexahydro, etc.) or unsaturated 3- to 14-membered ring group composed of carbon atoms and at least one heteroatom selected from N, O or S, preferably a 4- to 10-membered ring group, more preferably a 5- or 6-membered ring group; preferably having 1 to 4 heteroatoms, more preferably having 1 to 3 heteroatoms; for example, a 5- or 6-membered heterocyclic group having 1 to 3 heteroatoms selected from N, O or S. The heterocyclic group of the present application can be a monocyclic, bicyclic or tricyclic ring system, including fused rings (such as fused rings formed together with another heterocyclic ring or another aromatic carbon ring).

[0041] The mass transfer method for Micro-LEDs comprises the following steps:

[0042] S1. Providing a first substrate 5 having Micro-LED chips 8;

[0043] S2. Coating a bonding layer 6 having a polyamide composition on the first substrate 5, the bonding layer 6 covering the first substrate 5 and encapsulating the Micro-LED chips 8; the thickness of the bonding layer 6 is greater than the thickness of the Micro-LED chips 8; and curing the bonding layer 6;

[0044] S3. Bond the second substrate 7 to the cured and film-formed bonding layer 6 by vacuum lamination from the side away from the first substrate. The second substrate is a transparent substrate.

[0045] S4. Dissociate and release the Micro-LED chip from the first substrate with a laser, and separate the second substrate 7 from the first substrate 5. The Micro-LED chip is transferred to the second substrate 7 through the bonding layer.

[0046] S5. Then, dissociate and release the Micro-LED chip from the second substrate with a laser and transfer it to a TFT substrate or a circuit board with circuitry.

[0047] The polyamide composition of the present application comprises formula (I):.

[0048]

[0049] In formula (I), n is an integer from 1 to 200, preferably an integer from 5 to 150, more preferably an integer from 5 to 50.

[0050] R1, R2, and R3 are each independently divalent groups, including but not limited to C1-C 14 alkyl, C6-C 14 aryl or aralkyl, or a group containing a heteroatom-containing unsaturated group; and R1, R2, and R3 thereof may be a single repeating group or a combination of two or more different groups.

[0051] According to an embodiment of the present application, R1 or R2 or R3 may be selected from the following divalent groups:

[0052]

[0053] 5- or 6-membered nitrogen-containing heterocyclic group;

[0054] wherein n1-n8 may be an integer from 1 to 100. X is O, S, or the following divalent group.

[0055]

[0056] A and B may be any one of O, S, and CH2 groups.

[0057] The polyamide of formula (I) of the present application can be prepared by the following method:

[0058] (a) React an excess of diamine of formula (2) with benzoate of formula (3) to form a compound of formula (4):

[0059]

[0060] (b) After the reaction in step (a) is completed, a diester monomer (such as formula (5)) is added and reacted with the compounds of formula (2) and (4) to form a compound of formula (6);

[0061]

[0062] The integer of n7 can be controlled to be from 1 to 200 by the molar ratio of formula (3) to formula (5).

[0063] According to an embodiment of the present application, the polyamide composition of the present application may include a polyamide and a solvent. For example (but not limited thereto), the solvent may be selected from the following group: dimethyl sulfoxide (DMSO), diethyl sulfoxide, N,N-dimethylformamide (DMF), N,N-diethylformamide, N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), N-vinyl-2-pyrrolidone (NVP), phenol, o-cresol, m-cresol, p-cresol, xylenol, halogenated phenol, catechol, tetrahydrofuran (THF), dioxane, dioxolane, propylene glycol methyl ether (PGME), tetraethylene glycol dimethyl ether (TGDE), methanol, ethanol, butanol, butyl cellosolve, γ-butyrolactone (GBL), xylene, toluene, hexamethyl phthalic amide, propylene glycol methyl ether acetate (PGMEA), and mixtures thereof; the solvent is preferably a polar aprotic solvent, for example, a solvent selected from the following group: dimethyl sulfoxide (DMSO), diethyl sulfoxide, N,N-dimethylformamide (DMF), N,N-diethylformamide, N,N-dimethylacetamide (DMAc), N,N-diethylacetamide, N-methyl-2-pyrrolidone (NMP), N-ethyl-2-pyrrolidone (NEP), γ-butyrolactone (GBL).

[0064] According to an embodiment of the present application, based on the total weight of the overall polyamide, the content of the polyamide is about 10 wt% to about 70 wt%, preferably about 15 wt% to about 50 wt%, and the remaining part is the solvent. The amount of the solvent is not particularly limited as long as it can make the composition conducive to coating.

[0065] There are no special restrictions on the preparation method of the polyamide of the present application. For example, after the polyamide shown in formula (I) is prepared, an appropriate solvent can be added, and additives (such as leveling agents, defoaming agents, coupling agents, dehydrating agents, catalysts, etc.) can be added in appropriate proportions as needed, and then stirred evenly under a nitrogen system to obtain it.

[0066] The bonding layer with the polyamide composition described in the present application can be obtained by coating the aforementioned polyamide composition on a substrate and curing it by heating. The polyamide of the present application is a thermosetting polyamide polymer, which has excellent physical properties, mechanical properties and low coefficient of thermal expansion. The aforementioned substrate can be any known to those skilled in the relevant art, such as glass, sapphire or quartz.

[0067] In the traditional method for synthesizing polyamide, it is not easy to control the molecular weight. However, due to too high molecular weight, the viscosity is too large, resulting in poor operability and easy to produce defects such as poor leveling during coating.

[0068] The molecular weight of the polyamide oligomer of the present application is lower than that of the traditional polyamide, and the viscosity is smaller, with good operability. It can be formulated into a high solids content, and at this time, the coating contains less solvent. Therefore, the soft baking time can be shortened and the soft baking temperature can be reduced, reducing the volume shrinkage phenomenon caused by the volatilization of a large amount of solvent. It has the advantages of fast drying and film-forming speed and reducing the number of coating times required to reach the required thickness of the product.

[0069] Using the polyamide composition of the present application, it has a low glass transition temperature and high absorption and other characteristics. Therefore, it can be applied to the transfer material for low-temperature bonding and laser dissociation of Micro-LEDs, and has the functions of both a laser dissociation layer and a bonding layer; compared with the double-layer structure, it can provide a high yield of mass transfer.

[0070] The thickness of the polyamide composition coated in the present application depends on the height of the Micro-LED chip. The thickness of the polyamide composition is greater than the height of the Micro-LED, and the preferred range of the polyamide thickness is 1.01 to 100 times that of the LED chip, and the best preferred range of the polyamide thickness is 1.01 to 10 times that of the LED chip.

[0071] The curing temperature of the polyamide composition provided in the present application depends on the boiling point of the solvent used. Generally, after soft baking at 50 to 100 °C, it is then cured and leveled at a high temperature to improve the surface flatness.

[0072] After the polyamide composition provided in the present application is cured into a film, the bonding method used is vacuum pressing. The vacuum degree is 0.01 to 10 Torr, the bonding temperature is 100 to 250 °C, and the bonding pressure is 0.1 to 10 kg / cm 2 . The bonding time is 1 to 10 min.

[0073] After the polyamide composition provided by this application is cured into a film, it can be stored at room temperature without affecting laser dissociation or adhesion characteristics. Compared with epoxy materials, after curing, epoxy materials need to be processed within a short time, otherwise the adhesion characteristics will be affected and the yield will become poor.

[0074] After the laser dissociation of the polyamide composition provided by this application, plasma can be used for cleaning.

[0075] The above laser can be an Nd-YAG laser or a CO2 laser, with wavelengths of 248nm, 266nm or 355nm, but not limited thereto.

[0076] Examples

[0077] The abbreviations mentioned in the following examples are defined as follows:

[0078] A-0:

[0079] A-1:

[0080] A-2:

[0081] A-3:

[0082] A-4:

[0083] A-5:

[0084] A-6:

[0085] A-7:

[0086] A-8:

[0087] B-1:

[0088] B-2:

[0089] B-3:

[0090] B-4:

[0091] B-5:

[0092] Preparation Example 1:

[0093] Take 0.02 moles of methyl benzoate (abbreviated as A-0) and place it in a 1 L reaction kettle filled with nitrogen. Add 100 mL of DMSO, add 0.5 moles of B-1 at 50 °C, and then add 0.5 wt% phosphoric acid. Stir for 2 hours. After warming back to 25 °C, add 0.49 moles of A-1 and stir for 1 hour. Then raise the temperature to 50 °C and stir for 12 hours. Add DMSO to adjust the solid content to 20% to obtain a polyamide composition (PA-1).

[0094] Preparation Examples 2 to 19:

[0095] Using the same method as in Preparation Example 1, as shown in Table 1, replace A-1 in the original Preparation Example 1 with A-2 to A-8 respectively to form Polyamide Preparation Examples 2 - 8, and obtain the corresponding polyamide compositions (PA-2 to PA-8);

[0096] Using the same method as in Preparation Example 1, as shown in Table 1, replace A-1 in Preparation Example 1 with A-8, and replace B1 in Preparation Example 1 with B-2 to B-5 respectively to obtain Preparation Examples 9 - 12, and obtain the corresponding polyamide compositions (PA-9 to PA-12);

[0097] Using the same method as in Preparation Example 1, as shown in Table 1, replace A-1 in Preparation Example 1 with A-6, and replace B1 in Preparation Example 1 with B-3 to B-5 respectively to obtain Preparation Examples 13 - 15, and obtain the corresponding polyamide compositions (PA-13 to PA-15);

[0098] Using the same method as in Preparation Example 1, as shown in Table 1, replace A-1 in Preparation Example 1 with A-4 / A-8 and A-6 / A-8 with a molar ratio of 0.5:0.5 respectively, and replace B-1 in Preparation Example 1 with B-3 to obtain Preparation Examples 16 - 17, and obtain the corresponding polyamide compositions (PA-16 to PA-17);

[0099] Using the same method as in Preparation Example 1, as shown in Table 1, replace A-1 in Preparation Example 1 with A-4 / A-8 and A-6 / A-8 with a molar ratio of 0.5:0.5 respectively, and replace B-1 in Preparation Example 1 with B-5 to obtain Preparation Examples 18 - 19, and obtain the corresponding polyamide compositions (PA-18 to PA-19).

[0100] PA1:

[0101] PA2:

[0102] PA3:

[0103] PA4:

[0104] PA5:

[0105] PA6:

[0106] PA7:

[0107] PA8:

[0108] PA9:

[0109]

[0110] PA10:

[0111] PA11:

[0112]

[0113] PA12:

[0114] PA13:

[0115]

[0116] PA14:

[0117] PA15:

[0118]

[0119] PA16:

[0120]

[0121] PA17:

[0122]

[0123] PA18:

[0124]

[0125] PA19:

[0126]

[0127] Examples:

[0128] The polyamide compositions prepared in Preparation Examples 2 to 19 were coated on a quartz glass or copper foil substrate by spin coating. First, they were soft-baked on a hot plate at 90 °C for 5 to 15 minutes to prevent surface adhesion, and then high-temperature cured and leveled in a nitrogen oven at a curing temperature of 150 to 250 °C for 1 hour. The samples to be tested were obtained (the thickness of the dried coating was 5 μm).

[0129] Comparative Example:

[0130] 0.5 moles of dimethyl terephthalate (abbreviated as A-1) was placed in a 1 L reactor filled with nitrogen. 100 mL of DMSO was added. 0.5 moles of B-1 was added at 50 °C, and then 0.5 wt% phosphoric acid was added. The mixture was stirred for 12 hours. DMSO was added again to adjust the solid content to 10%, obtaining a polyamide composition (PA-0).

[0131] Using the polyamide composition of the comparative example, since the viscosity was not controlled, the viscosity was too high to be coated.

[0132] <Test Method>

[0133] 1. Glass transition temperature test:

[0134] The PA sample coated on the copper foil substrate was etched with an acidic copper etching solution, then washed with pure water and dried in an oven. It was sent to a DSC to measure its glass transition temperature. The test results are recorded in Table 1.

[0135] 2. Ultraviolet light absorbance test:

[0136] The absorbance sample was coated on quartz glass, and its absorbance value was measured with an ultraviolet-visible spectrometer. Its thickness was controlled at 1 μm, and the test results are recorded in Table 2.

[0137] 3. Bonding adhesion test:

[0138] The polyamide film coated on the non-alkali glass was bonded to another sapphire substrate by vacuum bonding. The fixed vacuum pressure was below 0.1 Torr, and the fixed pressure was 0.5 kg / cm 2 , and the fixed bonding time was 5 minutes. The bonding temperature was the glass transition temperature plus 50 °C. After bonding, the sample was cut into a 1*1 cm size sample, and the interface adhesion (kg / cm 2 ) was confirmed with a tensile testing machine. The test results are recorded in Table 3.

[0139] 4. Laser dissociation test:

[0140] The polyamide film coated on the non-alkali glass was bonded to another sapphire substrate by vacuum bonding, and then the dissociation energy test was performed with a laser of a specific wavelength. The test results are recorded in Table 4.

[0141] 5. Polyamide composition thickness test:

[0142] The polyamide composition was coated on the red light Micro-LED chip substrate. After baking and hardening, it was bonded to another transparent substrate by vacuum bonding. Whether there would be fragmentation due to different polyamide composition thicknesses and bonding pressures was observed and recorded in Table 5.

[0143] <Test Results>

[0144] Table 1 Test Results of Glass Transition Temperature

[0145]

[0146] Note 1: Without indicating the molar ratio, it means using 100% single monomer.

[0147] Table 2 Test Results of Ultraviolet Light Absorbance

[0148] Polyamide Examples A(@248nm) A(@266nm) A(@355nm) PA-1 0.37 0.21 0.09 PA-2 0.41 0.24 0.11 PA-3 0.49 0.30 0.12 PA-4 0.51 0.34 0.14 PA-5 0.48 0.28 0.12 PA-6 0.55 0.35 0.15 PA-7 0.13 0.02 0 PA-8 0.31 0.15 0.08 PA-9 0.21 0.15 0.09 PA-10 0.37 0.21 0.10 PA-11 0.36 0.19 0.09 PA-12 0.38 0.2 0.09 PA-13 2.29 2.18 1.21 PA-14 2.15 2.07 1.05 PA-15 2.22 2.13 1.15 PA-16 2.31 2.32 1.24 PA-17 1.97 1.88 1.04 PA-18 2.29 2.27 1.11 PA-19 1.82 1.75 1.01

[0149] Note 1: The above are the measurement data for a thickness of 1 μm.

[0150] Table 3 Test Results of Bonding Adhesion

[0151] Polyamide Examples Bonding Temperature (°C) Kg / cm2 PA-1 201 35 PA-2 223 32 PA-3 215 29 PA-4 248 25 PA-5 187 37 PA-6 199 34 PA-7 123 47 PA-8 162 41 PA-9 82 45 PA-10 211 36 PA-11 204 37 PA-12 228 32 PA-13 268 21 PA-14 251 23 PA-15 259 22 PA-16 223 31 PA-17 232 33 PA-18 233 32 PA-19 241 35

[0152] Table 4 Test Results of Laser Dissociation

[0153]

[0154] Note 1: NA means the energy is greater than 2000 mJ / cm 2 。

[0155] Table 5 Test Results of Thickness and Bonding Pressure of Polyamide Composition

[0156]

[0157] Note 1: The height of the Micro-LED chip (including electrodes) is 35 μm.

[0158] Note 2: NG means fragmentation occurred, and OK means no damage.

[0159] According to the experimental data in Table 1, when there are more aromatic ring structures, the structure is more rigid and the glass transition temperature is higher, as shown in PA-1 to PA-4. When esters and diamines are monomers of soft segments, their glass transition temperature is the lowest, such as PA-7 and PA-9. And according to the examples of PA-1 to PA-19, their highest glass transition temperature is 218 °C, and the lamination temperature needs to be 268 °C, slightly higher than the specification value of 250 °C. Therefore, two different ester monomers can be used in combination with diamine monomers to form a lower glass transition temperature.

[0160] The data in Table 2 are the absorption values of each example at wavelengths of 248 / 266 / 355 nm. According to the data, polyaromatic rings and heteroatoms contribute to increasing the absorption value. For example, PA-4 to PA-6 have better absorption. When both the diester and diamine are aromatic rings (PA-13 to PA16), their absorption values at 248 nm / 266 nm can exceed 2. However, due to the relatively high glass transition temperature, soft-segment diester monomers (PA-16 to PA-19) are used to maintain the absorption values at above 1.0 at the three wavelengths.

[0161] The data in Table 3 are the corresponding lamination temperature parameters set according to the glass transition temperature in Table 1, and their tensile strength values are measured. According to the experimental results, the tensile strength values are all greater than 20 kg / cm 2 。

[0162] From the data in Table 4, it can be seen that if it is desired that the laser release energy at 248 / 266 nm is less than 1000 mJ, the corresponding absorption should be as high as possible. From the examples in the table, the lowest laser release energy can be 350 mJ (@248 nm).

[0163] From the data in Table 5, it can be seen that chip fragmentation is related to the thickness of the polyamide composition, the lamination pressure, and the lamination temperature. In the examples with a relatively high lamination temperature, the thickness of the polyamide composition should be more than twice the chip height to avoid chip fragmentation under a relatively high lamination pressure, such as the example of PA-16. When the lamination temperature is relatively low, the thickness of the polyamide composition can be 1 to 1.5 times the chip height according to the lamination pressure.

Claims

1. A mass transfer method for Micro-LED, characterized in that: The following steps are involved: S1. Providing a first substrate having a Micro-LED chip; S2, coating a bonding layer having a polyamide composition on the first substrate, the bonding layer covering the first substrate and encapsulating the Micro-LED chip; the thickness of the bonding layer is greater than the thickness of the Micro-LED chip; and curing the bonding layer; S3, bonding the second substrate to the cured bonding layer by vacuum pressing from a side away from the first substrate, wherein the second substrate is a transparent substrate; S4, using a laser to release the Micro-LED chip from the first substrate, and to separate the second substrate from the first substrate; the Micro-LED chip is transferred to the second substrate through the bonding layer; S5, using laser to release the Micro-LED chip from the second substrate and transfer it to a TFT substrate or circuit board with circuits. The content of polyamide in the polyamide composition is 10-70wt%, and the rest is solvent and additives; the polyamide is a copolymer of diester and diamine, and has a structure shown in formula (I): n is an integer from 1 to 200; R1, R2, R3 are independently selected from C 6-14 At least one of an aryl group, an alkyl group, an aralkyl group, an alkoxy group, a hydroxyl group, a siloxane group, a polyethylene glycol group, a polypropylene glycol group, a heteroaryl group, and a 5- or 6-membered nitrogen-containing heterocyclic group.

2. The method for mass transfer according to claim 1, characterized in that: In the step S4, after the Micro-LED chip is transferred to the second substrate, the step of cleaning the second substrate with the Micro-LED chip and removing residual glue is also included.

3. The method for mass transfer according to claim 1 or 2, characterized in that: Repeating steps S3 and S4 can arrange the three primary colors or different chip spacings.

4. The method for mass transfer according to claim 1, characterized in that: The R1, R2, and R3 are independently selected from the following groups: 5- or 6-membered nitrogen-containing heterocyclic group; n1-n8 is an integer from 1 to 100; X is O, S or the following divalent groups: A and B are each independently selected from one of O, S and CH2 groups.

5. The method for mass transfer according to claim 1, characterized in that: The glass transition temperature Tg of the polyamide is 30-250°C; preferably, the glass transition temperature of the polyamide is 100-200°C.

6. The method for mass transfer according to claim 1, wherein: The thickness of the bonding layer is 1.01-100 times the thickness of the Mico-LED chip. Preferably, the thickness of the bonding layer is 1.01-10 times the thickness of the Mico-LED chip.

7. The method for mass transfer according to claim 1, characterized in that: The diester or diamine monomer may be one or more mixed monomers.

8. The method for mass transfer according to claim 1, characterized in that: The energy released by the laser in steps S4 and S5 is 100-2000 J / cm 2 Preferably, the energy released by the laser in steps S4 and S5 is 300-1000 J / cm 2 .

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