Conductive silver glue for Micro-Led pasting and preparation method and application method thereof

Abstract

The present invention discloses a conductive silver paste for Micro-LED pasting and a preparation method and application method thereof, wherein the preparation method comprises: step S1: preparing materials by mass; step S2: dispersing silver salt, alcohol amine and alcohol ester solvent with a planetary dispersing device under light-proof conditions to obtain a uniform liquid silver amine complex liquid, and storing it in a light-proof frozen state for standby use; step S3: dispersing the liquid epoxy resin, anhydride curing agent and silver complex liquid with a planetary dispersing device under sunlight-proof conditions to obtain a conductive silver paste with a viscosity of 1000cps-5000cps. This scheme can be applied to EHD nozzles with a diameter of 3μm, and can also ensure that the interface adhesion between the receiving substrate and the Micro-LED chip is greater than the force between the chip and the substrate, and after the conductive silver paste is cured, a conductive path is formed to realize conductive contact between the Micro-Led chip and the metal substrate, so that the Micro-Led chip is 100% lit.

Description

Technical Field

[0001] The invention relates to the field of adhesives, and in particular to a conductive silver adhesive for Micro-Led pasting in a Micro-Led mass transfer process, and a preparation method and an application method thereof. Background Art

[0002] Micro light emitting diode (Micro LED) usually refers to the traditional Micro LED chip structure, which is reduced to less than 50μm in size and regularly arranged on thin film transistors (TFT) or complementary metal oxide semiconductors (COMS), which significantly improves the display resolution and image quality, has a wider viewing angle, higher contrast, and better image quality. It is suitable for a variety of display scenarios such as virtual reality, small projectors, micro displays, visible light communications, and medical research. Compared with OLED, the self-luminous technology display allows the integration of sensors and circuits to achieve embedded sensing functions. In addition, Micro LED also has the characteristics of high clarity, high brightness, good contrast, and high response speed. Due to the high integration of Micro LED, the overly dense Micro LED setting leads to low utilization of Micro LED, resulting in waste. Therefore, in actual use, it is necessary to transfer Micro LED to a sparsely arranged driver circuit board through a large amount (tens of thousands or even hundreds of thousands of pieces).

[0003] Existing Micro-LED mass transfer technologies include Figure 1 As shown, a wafer substrate carrying a large number of Micro LEDs is usually covered on a receiving substrate provided with a conductive adhesive, and then the Micro LED chip is separated from the wafer substrate. The common separation method is laser separation, or as in the invention patent with the authorization announcement number CN111477650B, the photosensitive adhesive layer is irradiated by a light spot array to separate the Micro LED chip from the wafer substrate, so that the Micro LED chips are transferred to the receiving substrate in batches. The current research focus of Micro-LED mass transfer technology is on the separation of Micro LED and wafer substrate, and after the Micro LED chip is transferred to the receiving substrate, its lighting rate is closely related to the conductive adhesive provided on the surface of the receiving substrate.

[0004] In the Micro-LED mass transfer technology, it is necessary to ensure that the interface adhesion between the receiving substrate and the Micro-LED chip is greater than the force between the chip and the substrate. Therefore, the regulation of interface adhesion is crucial to mass transfer. At the same time, the Micro LED chips need to be arranged according to a certain pattern, so they need to be fixed-point pasted on the receiving substrate. Since the size of the Micro LED chip is ≤50μm (preferably 10μm and below), the dispensing interface of the conductive glue should also be controlled within a diameter range of 50μm (preferably 10μm). To ensure the dispensing size of the conductive glue, an EHD nozzle with a caliber of 3μm-5μm is required to spray the conductive glue on the receiving substrate. When the viscosity of the conductive glue is too large, the EHD nozzle cannot spray. In addition, it is also necessary to ensure that the conductive glue will not wetting and diffuse on the surface of the receiving substrate, thereby causing a short circuit, as well as the conductive properties of the conductive glue, so as to ensure that the Micro LED chip is 100% lit.

[0005] Common conductive adhesive materials include: 1. Traditional solder paste SMT packaging and silver glue sealing use micron-level metal conductive fillers such as silver / tin. Its printing / dispensing process is difficult to prepare electrodes with a size of less than 50μm, so it cannot be used for Micro-LED chip pasting; 2. Nano conductive ink, such as the inkjet conductive ink disclosed in the invention with authorization announcement numbers CN101560349B and CN115058153A, has low interfacial adhesion (viscosity <100 pa.s), and it is difficult for Micro-Led chips to adhere to the conductive ink during the mass transfer process. In addition, there is no strong adhesive phase in the nano conductive ink, and the bonding between the chip and the receiving substrate after curing is weak, which affects the photoelectric properties of Micro-Led; 3. Conductive adhesive containing conductive metal powder is easy to form agglomeration, and the finer the powder, the more obvious the soft agglomeration, resulting in clogging of the EHD nozzle; Summary of the invention

[0006] Therefore, in order to solve the above problems and achieve 100% lighting of the Micro LED chip, the present invention provides a conductive silver paste for Micro-Led pasting and a preparation method and an application method thereof.

[0007] The present invention is achieved through the following technical solutions:

[0008] The preparation method of conductive silver paste for Micro-Led pasting comprises the following steps:

[0009] Step S1: Prepare the following materials by weight:

[0010] 1.5-15 parts of silver salt;

[0011] 0.5 to 5 parts of alcoholamine;

[0012] 15-30 parts of liquid epoxy resin;

[0013] 2.5-5 parts of anhydride curing agent;

[0014] 40-70 parts of alcohol ester solvent;

[0015] The liquid epoxy resin is a low-viscosity epoxy resin with a viscosity of 3000mpa.s-10000mpa.s, and the acid anhydride curing agent is a liquid acid anhydride curing agent;

[0016] Step S2: dispersing the silver salt, alcohol amine and alcohol ester solvent in a light-proof condition using a planetary dispersing device to obtain a uniform liquid silver amine complex solution, and storing it in a light-proof and frozen state for later use;

[0017] Step S3: dispersing the liquid epoxy resin, anhydride curing agent and silver complex liquid using a planetary dispersing device under sunlight-proof conditions to obtain a conductive silver paste with a viscosity of 1000 cps-5000 cps.

[0018] Preferably, the number of C atoms in the molecule of the alcoholamine does not exceed 4.

[0019] Preferably, the silver salt is one or more of silver oxalate, silver acetate, and silver carboxylate.

[0020] Preferably, the alcoholamine is one or more of ethanolamine, triethanolamine, propanolamine and butanolamine.

[0021] Preferably, the acid anhydride curing agent is one or more of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methylnadic anhydride.

[0022] Preferably, the alcohol ester solvent is one or more of ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol butyl ether acetate, ethylene glycol butyl ether acetate, and diethylene glycol butyl ether acetate.

[0023] The conductive silver paste for Micro-Led pasting is prepared by the preparation method of the conductive silver paste for Micro-Led pasting as described above.

[0024] The application method of conductive silver paste for Micro-Led pasting is characterized by:

[0025] Step I: Prepare the conductive silver glue for Micro-Led pasting as described above;

[0026] Step II: The conductive silver glue is printed on the receiving substrate by EHD, the EHD nozzle diameter is 3μm-5μm, and spherical conductive droplets with a diameter of <10μm are formed at each dispensing position after printing;

[0027] Step III: Place the carrier carrying a large number of Micro-Led chips upside down on a receiving substrate sprayed with spherical conductive silver glue, so that each Micro-Led chip is covered on the corresponding spherical conductive droplet;

[0028] Step IV: separating the Micro-Led chip from the carrier;

[0029] Step V: Bake the receiving substrate with the Micro-Led chip at 60°C for 10 minutes, and then continue to heat it to 160°C for curing for 30 minutes.

[0030] Preferably, steps I to III are all carried out at 20°C-25°C.

[0031] Preferably, a water drop angle between the spherical conductive droplet and the surface of the receiving substrate is greater than 30°.

[0032] The beneficial effects of the technical solution of the present invention are mainly reflected in:

[0033] 1. In the conductive silver glue for Micro-Led pasting disclosed in the present invention, silver salt is mixed with alcohol amine and alcohol ester solvents to form a silver amine complex liquid, which is then mixed with liquid epoxy resin and acid anhydride curing agent. No additional conductive powder is added, and the EHD nozzle will not be blocked due to powder agglomeration in the conductive glue or excessive colloid viscosity. It can be applicable to EHD nozzles with a diameter of 3μm. In addition, low-viscosity epoxy resin with a viscosity of 3000mpa.s-10000mpa.s and liquid acid anhydride curing agent are strictly formulated. The liquid acid anhydride curing agent is mutually soluble in the epoxy resin and the alcohol ester solvent, so that the viscosity of the conductive glue is between 1000cps-5000cps, ensuring that the conductive glue is applicable to EHD nozzles with a diameter of 3μm while also ensuring that the interface adhesion between the receiving substrate and the Micro-LED chip is greater than the force between the chip and the substrate.

[0034] 2. The silver-amine complex liquid of the conductive silver glue used for Micro-Led pasting is mixed with silver salt through alcohol amine and is in liquid state before curing. When the conductive silver glue is heated and cured, the alcohol amine undergoes a reduction reaction. The silver-amine complex in the conductive silver glue can be reduced to thin silver and nano-silver particles without adding other reducing agents. A conductive path is formed in the cured conductive silver glue, which can ensure conductive contact between the Micro-Led chip and the metal substrate, so that the Micro-Led chip is 100% lit.

[0035] 3. The water drop angle of the conductive silver glue is precisely controlled by the alcohol ester solvent so that the water drop angle is greater than 30°, thereby preventing the conductive silver glue from wetting and spreading after being coated on the surface of the receiving substrate, preventing short circuits caused by the expansion of the conductive silver glue, and further ensuring the lighting rate of the Micro-Led chip. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] Figure 1 It is a schematic diagram of the process of applying the conductive silver glue for Micro-Led pasting;

[0037] Figure 2 This is a partial scanning electron microscope image of the conductive silver paste for Micro-Led pasting prepared in Example 2 of the present invention;

[0038] Figure 3 yes Figure 2 Magnified image of . DETAILED DESCRIPTION

[0039] In order to make the purpose, advantages and features of the present invention more clearly and in detail, the following preferred embodiments are used for illustration and explanation. The embodiments are only typical examples of the application of the technical solution of the present invention. Any technical solution formed by equivalent replacement or equivalent transformation falls within the scope of protection claimed by the present invention.

[0040] At the same time, it is stated that in the description of the scheme, it should be noted that the terms "center", "upper", "lower", "left", "right", "front", "back", "inside", "outside" and the like indicate positions or positional relationships based on the positions or positional relationships shown in the drawings, which are only for the convenience and simplification of description, and do not indicate or imply that the device or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore cannot be understood as a limitation on the present invention. In the present invention, the meaning of "multiple" is two or more, unless otherwise clearly and specifically defined.

[0041] The present invention discloses a method for preparing a conductive silver paste for Micro-Led pasting, comprising the following steps:

[0042] Step S1: Prepare the following materials by weight:

[0043] 1.5-15 parts of silver salt;

[0044] 0.5 to 5 parts of alcoholamine;

[0045] 15-30 parts of liquid epoxy resin;

[0046] 2.5-5 parts of anhydride curing agent;

[0047] 40-70 parts of alcohol ester solvent;

[0048] The liquid epoxy resin is a low-viscosity epoxy resin with a viscosity of 3000mpa.s-10000mpa.s, and the acid anhydride curing agent is a liquid acid anhydride curing agent, which is miscible with the epoxy resin and the alcohol ester solvent. At the same time, due to the precise size of the Micro-Led chip, the conductive silver glue for Micro-Led pasting is usually sprayed on the receiving substrate using an EHD nozzle with a caliber of 3μm-5μm. The liquid acid anhydride curing agent can be used to avoid needle clogging during the spraying process. The combination with the low-viscosity epoxy resin can also effectively regulate the overall viscosity of the conductive silver glue to avoid blockage caused by too high viscosity or reduced adhesion due to too low viscosity.

[0049] Step S2: Dispersing the silver salt, alcohol amine and alcohol ester solvent with a planetary dispersing device under light-proof conditions to obtain a uniform liquid silver amine complex solution, and storing it in a dark and frozen state for standby use. In some embodiments, the revolution speed of the planetary dispersing device is 800RPM-1200RPM, and the rotation speed is 600RPM-800RPM. The dispersion time is not limited and can be adjusted according to the observation situation, which will not be described in detail here;

[0050] Step S3: Disperse the liquid epoxy resin, anhydride curing agent and silver complex liquid by a planetary dispersing device under sunlight-proof conditions to obtain a conductive silver paste with a viscosity of 1000cps-5000cps. In some embodiments, the revolution speed of the planetary dispersing device is 800RPM-1200RPM, and the rotation speed is 600RPM-800RPM. The dispersion time can be adjusted according to the observed situation, which will not be elaborated here. Within this viscosity range, the conductive silver paste can be sprayed on the receiving substrate through an EHD nozzle with a diameter of 3μm, and also has good adhesion performance, ensuring that all Micro-Led chips are transferred from the substrate to the silver paste.

[0051] In a preferred embodiment, the number of C atoms in the molecule of the alcoholamine does not exceed 4, and the alcoholamine is liquid at 20° C.-25° C. and has good solubility.

[0052] In some embodiments, the silver salt is one or more of silver oxalate, silver acetate, and silver carboxylate; the alcoholamine is one or more of ethanolamine, triethanolamine, propanolamine, and butanolamine; the acid anhydride curing agent is one or more of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride, and methylnadic anhydride; the alcohol ester solvent is one or more of ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol butyl ether acetate, ethylene glycol butyl ether acetate, diethylene glycol butyl ether acetate, etc.

[0053] The present invention also discloses a conductive silver paste for Micro-Led pasting, which is prepared by adopting the above-mentioned preparation method of the conductive silver paste for Micro-Led pasting.

[0054] As shown in Table 1 below, according to the above-mentioned preparation method of conductive silver paste for Micro-Led pasting, the following Examples 1 to 7 were prepared to obtain 7 kinds of conductive silver paste for Micro-Led pasting; at the same time, the following Comparative Examples 1 to 5 were provided to obtain 5 kinds of comparative conductive silver pastes, wherein, except that some material proportions of Comparative Examples 2 to 4 were different from the material proportions in the preparation method of conductive silver paste for Micro-Led pasting disclosed in the present invention, the remaining preparation steps and the types of materials used were all referred to the preparation method of conductive silver paste for Micro-Led pasting disclosed in the present invention; Comparative Example 1 used nanosilver instead of silver salt and alcohol amine, and the remaining material types and proportions and preparation processes were all referred to the preparation method of conductive silver paste for Micro-Led pasting disclosed in the present invention; Comparative Example 5 used solid anhydride curing agent (pyromellitic dianhydride powder) instead of liquid anhydride curing agent, and the remaining material types and proportions and preparation processes were all referred to the preparation method of conductive silver paste for Micro-Led pasting disclosed in the present invention.

[0055] Table 1: Material ratios of Examples 1 to 7 and Comparative Examples 1 to 4 in parts by mass;

[0056]

[0057] Subsequently, the viscosity of the conductive silver paste prepared in the above-mentioned embodiments 1 to 7 and comparative examples 1 to 5 was tested respectively, and the conductive silver paste prepared in the above-mentioned embodiments and comparative examples was spray-printed on the Al / Cu / Ag metal substrate through an EHD nozzle with a diameter of 3 μm. If a spherical conductive droplet with a diameter of <10 μm is formed on the metal substrate, the conductive droplet is tested for a water drop angle and a continuous spraying time. Finally, the Micro-Led chip (2*2mm bare silicon wafer) was transferred to the metal substrate printed with the conductive droplets to ensure that each Micro-Led chip was covered and pasted on the corresponding conductive droplet, and then the temperature was raised to 60°C, baked for 10 minutes, and continued to rise to 160°C for curing for 30 minutes. The lighting rate, bonding strength and lighting rate of the Micro-Led chip after curing were tested respectively. The test results are shown in Table 2 below:

[0058] Table 2: Test results of Examples 1 to 7 and Comparative Examples 1 to 4;

[0059]

[0060] As shown in Table 2 above, the bonding strength and lighting rate of the conductive silver paste for Micro-Led pasting prepared by Examples 1 to 7 are both high. At the same time, the viscosity of the conductive silver paste for Micro-Led pasting is within the range of 1000cps-5000cps, so it is not easy to cause material blockage, and the bonding performance of the conductive silver paste can be ensured; especially in Examples 2 and 6, the conductive silver paste not only has excellent bonding strength and lighting rate, but also has significantly better anti-aging performance than other examples and comparative examples. After aging at 120°C for 30 minutes, the lighting rate can still reach 100%. At the same time, the continuous spraying time is long (the continuous spraying time of the conductive silver paste prepared in Example 2 is >4hrs), it is not easy to cause material blockage at the nozzle, and the water drop angle of the spherical conductive droplets formed on the metal substrate is greater than 30°, and it is not easy to wet and diffuse to cause short circuit after dispensing.

[0061] Embodiments 3 and 7 can achieve a lighting rate of 100%, but since the ratio of silver salt and alcohol amine is significantly increased in Embodiment 3, its continuous spraying time is shorter than that of Embodiments 1 to 6. Although it does not affect other properties, if the ratio of silver salt and alcohol amine is further increased, blockage will occur in a shorter spraying time as shown in Control Example 4; Embodiment 7 uses a higher ratio of alcohol ester solvent compared to other embodiments, so the viscosity of the conductive silver paste prepared by Embodiment 7 is relatively low, and the water drop angle of the spherical conductive droplets formed on the metal substrate is also small, and the wettability is better, but no short circuit caused by the expansion of the conductive silver paste was found in the experiment, so its lighting rate is still 100%.

[0062] To further prove that the above-mentioned conductive silver paste for Micro-Led pasting can form a conductive path after curing, the conductive silver paste prepared in Example 2 was scraped on the PI film with a thickness of <10 μm, heated to 60°C, baked for 10 minutes, and further heated to 160°C and cured for 30 minutes to form a cured conductive adhesive layer. The cured conductive adhesive layer was magnified and observed using a scanning electron microscope (SEM), as shown in FIG. Figure 2 , Figure 3 As shown, it can be clearly seen that the uniformly dense silver particles are restored in the conductive adhesive layer after curing, and a conductive path is formed in the conductive adhesive layer, ensuring that the lighting rate of the Micro-Led chip reaches 100%.

[0063] As shown in Table 2 above, the continuous spraying time of the conductive silver paste prepared in Control Example 1 is significantly shorter than that of other embodiments and comparative examples, and its bonding strength is insufficient, resulting in a low lighting rate. This is because Control Example 1 uses nanosilver with an average particle size of 80 nm instead of silver salt and alcohol amine, and the nanosilver powder is prone to soft agglomeration during the dispersion process, causing blockage at the EHD nozzle, which in turn leads to the inability to spray continuously; Control Example 2 does not use alcohol ester solvents, so the viscosity is extremely high, so the problem of short continuous spraying time due to blockage is also caused; in Control Example 3, liquid epoxy resin and acid anhydride curing agent are not added, and silver ammonia complex is directly used as conductive silver paste, resulting in inability to use; Control Example 5 uses solid acid anhydride curing agent instead of liquid acid anhydride curing agent. On the one hand, the solid curing agent is easy to agglomerate and block, and on the other hand, the solid acid anhydride curing agent is difficult to dissolve in alcohol ester solvents compared to liquid acid anhydride curing agent, resulting in a short continuous spraying time of the conductive silver paste.

[0064] The present invention also discloses an application method of a conductive silver paste for Micro-Led pasting, which is characterized by: Step I: preparing the conductive silver paste for Micro-Led pasting as described above.

[0065] Step II: The conductive silver glue is printed on the receiving substrate by EHD, the EHD nozzle has a diameter of 3 μm-5 μm, and preferably an EHD nozzle with a diameter of 3 μm is used. After printing, spherical conductive droplets with a diameter of <10 μm are formed at each dispensing position.

[0066] Step III: Place the carrier carrying a large number of Micro-Led chips upside down on a receiving substrate sprayed with spherical conductive silver glue, so that each Micro-Led chip is covered on the corresponding spherical conductive droplet; in some embodiments, the carrier can directly use a wafer substrate (such as Figure 1 As shown), in some other embodiments, the carrier may also be other transfer carriers, such as the transfer carrier disclosed in the invention with authorization announcement number CN114220828B; or the transfer carrier disclosed in any other prior art, which will not be repeated again.

[0067] Step IV: Separate the Micro-Led chip from the carrier; in some embodiments, the separation method of the Micro-Led chip and the carrier can adopt a traditional laser heating separation method. In some other embodiments, other separation methods can also be used according to the connection method between the Micro-Led chip and the carrier, such as the method disclosed in the invention with publication number CN111477650A, which continuously acts on the photosensitive adhesive layer through a light spot array to reduce the adhesion and release the chip to fall to the target substrate. It will not be repeated here.

[0068] Step V: Bake the receiving substrate with the Micro-Led chip at 60°C for 10 minutes, and then continue to heat it to 160°C for 30 minutes to solidify the conductive silver glue between the Micro-Led chip and the receiving substrate. During the curing process, the alcohol amine undergoes a reduction reaction, reducing the silver ammonia complex into a thin silver layer and 100-200nm silver particles, and forming a conductive path between the Micro-Led chip and the receiving substrate.

[0069] In some embodiments, steps I to III are all performed at 20° C.-25° C., and a water drop angle between the spherical conductive droplet and the surface of the receiving substrate is greater than 30°.

[0070] There are many implementation methods of the present invention, and all technical solutions formed by equivalent transformation or equivalent transformation fall within the protection scope of the present invention.

Claims

1. A method for preparing conductive silver paste for Micro-Led pasting, characterized in that: The following steps are involved: Step S1: Prepare the following materials by weight: 1.5-15 parts of silver salt; 0.5 to 5 parts of alcoholamine; 15-30 parts of liquid epoxy resin; 2.5-5 parts of anhydride curing agent; 40-70 parts of alcohol ester solvent; The liquid epoxy resin is a low-viscosity epoxy resin with a viscosity of 3000mpa.s-10000mpa.s, and the acid anhydride curing agent is a liquid acid anhydride curing agent; Step S2: dispersing the silver salt, alcohol amine and alcohol ester solvent in a light-proof condition using a planetary dispersing device to obtain a uniform liquid silver amine complex solution, and storing it in a light-proof and frozen state for later use; Step S3: dispersing the liquid epoxy resin, the acid anhydride curing agent and the silver complex liquid using a planetary dispersing device under sunlight-proof conditions to obtain a conductive silver paste with a viscosity of 1000 cps-5000 cps.

2. The method for preparing the conductive silver paste for Micro-Led pasting according to claim 1, characterized in that: The number of C atoms in the molecule of the alcoholamine does not exceed 4.

3. The method for preparing the conductive silver paste for Micro-Led pasting according to claim 1, characterized in that: The silver salt is one or more of silver oxalate, silver acetate, and silver carboxylate.

4. The method for preparing the conductive silver paste for Micro-Led pasting according to claim 1, characterized in that: The alcoholamine is one or more of ethanolamine, triethanolamine, propanolamine and butanolamine.

5. The method for preparing the conductive silver paste for Micro-Led pasting according to claim 1, characterized in that: The acid anhydride curing agent is one or more of methyltetrahydrophthalic anhydride, methylhexahydrophthalic anhydride and methylnadic anhydride.

6. The method for preparing the conductive silver paste for Micro-Led pasting according to claim 1, characterized in that: The alcohol ester solvent is one or more of ethylene glycol ethyl ether acetate, diethylene glycol ethyl ether acetate, propylene glycol methyl ether acetate, propylene glycol butyl ether acetate, ethylene glycol butyl ether acetate, and diethylene glycol butyl ether acetate.

7. Conductive silver glue for Micro-Led pasting, characterized by: The conductive silver paste for Micro-Led pasting is prepared by the preparation method of any one of claims 1 to 6.

8. The application method of conductive silver paste for Micro-Led pasting is characterized by: Step I: Prepare the conductive silver paste for Micro-Led pasting as claimed in claim 7; Step II: The conductive silver glue is printed on the receiving substrate by EHD, the EHD nozzle diameter is 3μm-5μm, and spherical conductive droplets with a diameter of <10μm are formed at each dispensing position after printing; Step III: Place the carrier carrying a large number of Micro-Led chips upside down on a receiving substrate sprayed with spherical conductive silver glue, so that each Micro-Led chip is covered on the corresponding spherical conductive droplet; Step IV: separating the Micro-Led chip from the carrier; Step V: Bake the receiving substrate with the Micro-Led chip at 60°C for 10 minutes, and then continue to heat it to 160°C for curing for 30 minutes.

9. The method for applying the conductive silver paste for Micro-Led pasting according to claim 8, characterized in that: The step I and step II are both carried out at 20°C-25°C.

10. The method for applying the conductive silver paste for Micro-Led pasting according to claim 8, characterized in that: The water drop angle between the spherical conductive droplet and the surface of the receiving substrate is greater than 30°.

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