Mini / Micro LED

Abstract

The utility model relates to the technical field of LED display, and discloses a Mini / Micro LED. The Mini / Micro LED comprises a substrate, a plurality of anisotropic conductive adhesives and a plurality of Mini / Micro LED chips, and the substrate is provided with a plurality of bonding pads; each piece of anisotropic conductive adhesive is respectively and correspondingly arranged on each bonding pad; each piece of Mini / Micro LED chip is respectively and correspondingly arranged on each piece of anisotropic conductive adhesive; wherein each anisotropic conductive adhesive comprises an insulating adhesive layer and a plurality of insulating conductors, the insulating adhesive layer is respectively connected with the substrate and the Mini / Micro LED chip, the plurality of insulating conductors are all arranged in the insulating adhesive layer, and the insulating conductors are arranged in the insulating adhesive layer. And the insulating conductors penetrate through the insulating glue layer and are electrically connected with the Mini / Micro LED chip and the bonding pad respectively, so that stable conductivity is realized, simultaneous conduction of all the insulating conductors is not needed, the welding difficulty is reduced, and the welding quality is stable.

Description

TECHNICAL FIELD

[0001] The utility model relates to LED display technical field especially relates to a Mini / Micro LED. BACKGROUND

[0002] Micro light emitting diode (Micro-LED) usually refers to the LED chip size specification on the basis of traditional LED chip structure, and the size is reduced to within 200 microns, and red, green and blue three colors Micro LED are arranged on thin film transistor (TFT) or complementary metal oxide semiconductor (COMS) according to certain rules, then the micro device capable of realizing full-color display is formed. This kind of display has independently controlled display pixels, has independent light emitting control, high brightness, low power consumption, super high resolution and super high color saturation and so on, and the power consumption of Micro-LED micro display device is only about 10% of liquid crystal panel. Like OLED, it can realize each pixel single addressing, and single driving light emitting. Mini / Micro LED display technology has entered the accelerated development stage in the past two years.

[0003] In the prior art, the chip and the substrate are electrically connected by melting the tin paste, but the tin paste is not uniform in the melting process, the contact between the tin paste and the pads of the substrate and the positive and negative pins of the chip is insufficient, and false welding occurs, resulting in unstable electrical conductivity of the chip and the substrate. UTILITY MODEL CONTENTS

[0004] The utility model discloses a Mini / Micro LED, which aims to solve the technical problem of unstable electrical conductivity of the existing Mini / Micro LED.

[0005] To achieve the above-mentioned purpose, the utility model provides a Mini / Micro LED, Mini / Micro LED includes the substrate, the substrate is equipped with a plurality of pads;

[0006] A plurality of anisotropic conductive adhesives, each anisotropic conductive adhesive is correspondingly arranged on each pad;

[0007] A plurality of Mini / Micro LED chips, each Mini / Micro LED chip is correspondingly arranged on each anisotropic conductive adhesive;

[0008] Each of the anisotropic conductive pastes comprises an insulating adhesive layer and a plurality of insulating conductive bodies, the insulating adhesive layer is connected with the substrate and the Mini / Micro LED chip respectively, the plurality of insulating conductive bodies are arranged in the insulating adhesive layer, and the insulating conductive bodies penetrate the insulating adhesive layer to be electrically connected with the Mini / Micro LED chip and the pad respectively.

[0009] Further, in an embodiment, the insulating conductive body comprises an insulating film and a metal conductive particle ball, the insulating film is wrapped around the metal conductive particle ball, the top and bottom of the insulating film are respectively provided with a first avoiding opening and a second avoiding opening, and the top and bottom of the metal conductive particle ball are respectively electrically connected with the Mini / Micro LED chip and the pad through the first avoiding opening and the second avoiding opening.

[0010] Further, in an embodiment, the diameter of the metal conductive particle ball is 10-20 μm.

[0011] Further, in an embodiment, the material of the metal conductive particle ball is one of tin powder, silver powder, nickel powder, gold powder, tin alloy powder, copper powder, and aluminum powder.

[0012] Further, in an embodiment, the material of the insulating film is one of resin, polymer, or thermoplastic polymer.

[0013] Further, in an embodiment, the thickness of the insulating film is 3%-25% of the diameter of the metal conductive particle ball.

[0014] Further, in an embodiment, the material of the insulating adhesive layer is modified epoxy resin.

[0015] Further, in an embodiment, the pad comprises a positive pad and a negative pad, the Mini / Micro LED chip comprises a positive pin and a negative pin, the positive pin is electrically connected with the positive pad through the metal conductive particle ball, and the negative pin is electrically connected with the negative pad through the metal conductive particle ball.

[0016] Further, in an embodiment, the substrate can be a circuit board or a glass substrate.

[0017] Further, in an embodiment, the plurality of insulating conductive bodies are uniformly arranged in the insulating adhesive layer.

[0018] In the technical solution provided by this utility model, a substrate is provided with multiple pads, and an anisotropic conductive adhesive is provided on each pad. A Mini / Micro LED chip is then placed on the anisotropic conductive adhesive. Since the anisotropic conductive adhesive includes an insulating adhesive layer and multiple insulating conductors, the multiple insulating conductors are disposed on the insulating adhesive layer. The insulating adhesive layer fixes the Mini / Micro LED chip on the pad, and the multiple insulating conductors make the Mini / Micro LED chip and the pad electrically connected. Since multiple insulating conductors are provided in one anisotropic conductive adhesive, only one or two insulating conductors need to be electrically connected to the Mini / Micro LED chip and the pad to make the Mini / Micro LED chip light up normally and the conductivity is stable. It is not necessary for all insulating conductors to be conductive at the same time, which reduces the welding difficulty and ensures stable welding quality. Attached Figure Description

[0019] One or more embodiments are illustrated by way of example with reference to the accompanying drawings. These illustrations do not constitute a limitation on the embodiments. Elements having the same reference numerals in the drawings are denoted as similar elements. Unless otherwise stated, the figures in the drawings are not to be limited by scale.

[0020] Figure 1 This is a partial enlarged view of an embodiment of the Mini / Micro LED of this utility model;

[0021] Among them, 100 is a Mini / Micro LED; 10 is a substrate; 101 is a pad; 102 is a positive pad; 103 is a negative pad; 20 is an anisotropic conductive adhesive; 201 is an insulating adhesive layer; 202 is an insulating conductor; 203 is an insulating film; 204 is a metal conductive particle ball; 205 is a first clearance opening; 206 is a second clearance opening; 30 is a Mini / Micro LED chip; 301 is a positive lead; 302 is a negative lead; and 303 is the chip body. Detailed Implementation

[0022] To facilitate understanding of this utility model, a more detailed description is provided below with reference to the accompanying drawings and specific embodiments. It should be noted that when an element is described as being "fixed to" another element, it can be directly on the other element, or one or more intermediate elements may exist between them. When an element is described as being "connected to" another element, it can be directly connected to the other element, or one or more intermediate elements may exist between them. The terms "vertical," "horizontal," "left," "right," "inner," "outer," and similar expressions used in this specification are for illustrative purposes only. In the description of this utility model, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating relative importance or implying the number of indicated technical features. Thus, unless otherwise stated, features defined as "first" or "second" may explicitly or implicitly include one or more of that feature; "multiple" means two or more. The term "comprising" and any variations thereof mean non-exclusive inclusion, where one or more other features, integers, steps, operations, units, components, and / or combinations thereof may be present or added.

[0023] Furthermore, unless otherwise expressly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to fixed connections, detachable connections, or integral connections; they can refer to mechanical connections or electrical connections; they can refer to direct connections or indirect connections via an intermediate medium, or internal communication between two components. All technical and scientific terms used in this specification have the same meaning as commonly understood by one of ordinary skill in the art to which this invention pertains. The terminology used in this specification is for the purpose of describing particular embodiments only and is not intended to limit the invention. The term "and / or" as used in this specification includes any and all combinations of one or more of the associated listed items.

[0024] Furthermore, the technical features involved in the different embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0025] Please refer to Figure 1 An embodiment of this utility model discloses a Mini / Micro LED100.

[0026] In one embodiment, such as Figure 1 As shown, the Mini / Micro LED 100 includes a substrate 10, a plurality of anisotropic conductive adhesives 20 and a plurality of Mini / Micro LED chips 30. The Mini / Micro LED chips 30 are electrically connected to the substrate 10 through the anisotropic conductive adhesives 20.

[0027] The substrate 10 can be a circuit board or a glass substrate 10. The substrate 10 has a plurality of pads 101, including a positive pad 102 and a negative pad 103.

[0028] Multiple anisotropic conductive adhesives 20 are provided at the positions corresponding to multiple pads 101. Each anisotropic conductive adhesive 20 is disposed on each pad 101. Each anisotropic conductive adhesive 20 includes an insulating adhesive layer 201 and multiple insulating conductors 202. The insulating adhesive layer 201 is connected to the substrate 10 and the Mini / Micro LED chip 30, respectively. The multiple insulating conductors 202 are disposed within the insulating adhesive layer 201. The insulating adhesive layer 201 is fixedly connected to the substrate 10 and the Mini / Micro LED chip 30. The top and bottom of the insulating adhesive layer 201 are provided with a third clearance opening and a fourth clearance opening for each insulating conductor 202, so that one end of the insulating conductor 202 can be electrically connected to the pad 101 through the fourth clearance opening. The material of the insulating adhesive layer 201 is modified epoxy resin, so that the insulating adhesive layer 201 not only achieves insulation in the X-axis and Y-axis directions to avoid short circuits, but also serves to bond the Mini / Micro LED chip 30. The connection function of fixing the LED chip 30 to the pad 101 also enables the insulating conductor 202 to conduct in the Z-axis direction.

[0029] The Mini / Micro LED chip 30 can be an unencapsulated Mini / Micro LED chip 30 or an encapsulated Mini / Micro LED chip 30. Multiple Mini / Micro LED chips 30 are correspondingly disposed on multiple anisotropic conductive adhesives 20, with each Mini / Micro LED chip 30 disposed on each anisotropic conductive adhesive 20. The other end of the insulating conductor 202 is electrically connected to the Mini / Micro LED chip 30 through a third clearance port. Because multiple insulating conductors 202 are disposed in one anisotropic conductive adhesive 20, only one or two insulating conductors 202 need to be electrically connected to the Mini / Micro LED chip 30 and the pad 101, allowing the Mini / Micro LED chip 30 to light up normally with stable conductivity. It eliminates the need for all metal conductive particles to conduct simultaneously, reducing welding difficulty and ensuring stable welding quality. Of course, the more metal conductive particles that conduct, the more stable the conductivity and the longer the service life.

[0030] Furthermore, the insulating conductor 202 includes an insulating film 203 and a metal conductive particle sphere 204. The outer surface of the metal conductive particle sphere 204 is covered with an insulating film 203. The top and bottom of the insulating film 203 are respectively provided with a first clearance opening 205 and a second clearance opening 206, so that the top of the metal conductive particle sphere 204 can be exposed and pass through the first clearance opening 205 to be electrically connected to the Mini / Micro LED chip 30. The bottom of the metal conductive particle sphere 204 can be exposed and pass through the second clearance opening 206 to be electrically connected to the pad 101 of the substrate 10, thereby achieving conduction in the Z-axis direction and insulation in the X-axis and Y-axis directions to avoid short circuits. Moreover, multiple insulating conductors 202 are provided between a Mini / Micro LED chip 30 and the pad 101, so that only one or two insulating conductors 202 need to be electrically connected to the Mini / Micro LED chip 30 and the pad 101 to normally light up the Mini / Micro LED chip 30, avoiding unstable conductivity caused by poor soldering.

[0031] Specifically, the material of the metal conductive particle spheres 204 is one of tin powder, silver powder, nickel powder, gold powder, tin alloy powder, copper powder, and aluminum powder. Tin powder is preferred as the material of the metal conductive particle spheres 204 because tin powder has good conductivity. The insulating film 203 is made of resin, polymer, or thermoplastic polymer, and its chemical composition differs from that of the insulating adhesive layer 201. This prevents the insulating film 203 from dissolving in the insulating adhesive layer 201 during heating. The insulating film 203 coats the surface of the metal conductive particle spheres 204, and its thickness is 3%-25% of the diameter of the metal conductive particle spheres 204. This makes the insulating film 203 relatively thin, allowing it to soften easily under heating during manufacturing. Under vertical pressure, the insulating film 203 is also prone to cracking in the Z-axis direction, forming a first clearance opening 205 and a second clearance opening 206. This enables the Mini / Micro LED 100 to conduct in the Z-axis direction and insulate in the X and Y-axis directions, preventing short circuits.

[0032] Furthermore, the pad 101 includes a positive pad 102 and a negative pad 103, both of which are disposed on the same surface of the substrate 10 and face towards the Mini / Micro LED chip 30. The LED chip 30 includes a positive electrode pin 301, a negative electrode pin 302, and a chip body 303. The positive electrode pin 301 and the negative electrode pin 302 are both disposed on the same surface of the chip body 303 and face the positive electrode pad 102 and the negative electrode pad 103, respectively. The positive electrode pin 301 is electrically connected to the metal conductive particle ball 204 through a first clearance port 205, and the positive electrode pad 102 is electrically connected to the metal conductive particle ball 204 through a second clearance port 206. That is, the positive electrode pin 301 is electrically connected to the positive electrode pad 102 through the metal conductive particle ball 204. The negative electrode pin 302 is electrically connected to the metal conductive particle ball 204 through the first clearance port 205, and the negative electrode pad 103 is electrically connected to the metal conductive particle ball 204 through the second clearance port 206. The negative electrode pin 302 is electrically connected to the negative electrode pad 103 through the metal conductive particle ball 204. Furthermore, the diameter of the metal conductive particle sphere 204 is 10μm-20μm, and the thickness of the insulating film 203 is 3%-25% of the diameter of the metal conductive particle sphere 204, making the insulating conductor 202 small in size. Therefore, there are multiple insulating conductors 202 between the positive electrode pin 301 and the positive electrode pad 102, and multiple insulating conductors 202 between the negative electrode pin 302 and the negative electrode pad 103. Moreover, the maximum driving current of each Mini / Micro LED chip 30 is usually less than 3-5mA. Under normal operation, the driving current is often only a few tenths of a milliampere. Therefore, only one insulating conductor 202 is electrically connected to the Mini / Micro LED chip 30 and the pad 101. Similarly, only one insulating conductor 202 is needed to electrically connect the negative electrode pin 302 and the negative electrode pad 103 to enable the Mini / Micro LED chip 30 to light up normally. The conductivity is good, and it is not necessary for all metal conductive particles to be conductive at the same time, which reduces the welding difficulty and ensures stable welding quality.

[0033] The present invention also discloses a first embodiment of a method for manufacturing Mini / Micro LEDs, comprising:

[0034] S1. Prepare metal conductive particle spheres by mechanical separation process or spraying process, wherein the diameter of the metal conductive particle spheres is 10μm-20μm;

[0035] In this step, the metal conductive particles are made of one or more of the following materials: tin powder, silver powder, nickel powder, gold powder, tin alloy powder, copper powder, and aluminum powder, which enables the metal conductive particles to conduct electricity.

[0036] For example, when the material of the conductive metal particles is tin balls, the specific steps for preparing conductive metal particle balls using a mechanical separation process are as follows: Tin powder is heated above its melting point, making it liquid; the molten tin is divided into tiny droplets using a high-speed rotating disk or vibrating nozzle, and the droplet diameter is controlled to 10μm-20μm by controlling the rotation speed and vibration frequency of the rotating disk; the liquid tin droplets form spheres under centrifugal or mechanical force, and due to surface tension, the molten tin naturally tends to form spheres; the liquid tin droplets are rapidly cooled in air or an inert gas (such as nitrogen) to solidify into tin balls with a diameter of 10μm-20μm; tin balls meeting the required size are screened using a sieve or particle size classification device, and unqualified particles are removed, finally obtaining tin balls with a diameter of 10μm-20μm. The principle of preparing tin balls using a mechanical separation process is to form tin balls by separating molten tin metal into fine particles. This method typically involves mechanical force or vibration to control the size and distribution of the liquid tin droplets.

[0037] When the material of the conductive metal particles is tin balls, the specific steps for preparing conductive metal particle balls using a spraying process are as follows: Tin powder is heated above its melting point to completely melt it; the molten tin is sprayed through a nozzle while a high-pressure inert gas (such as nitrogen or argon) disperses the tin flow into tiny droplets; the molten tin is introduced into a high-speed rotating disc or spray cup, where centrifugal force throws the molten tin out to form tiny tin droplets; during the spraying process, the tin droplets are rapidly cooled in air or inert gas, and due to surface tension, they naturally form spheres and solidify; the cooled tin balls are collected by a collection device, and then separated into tin balls with a diameter of 10μm-20μm using screening or grading equipment. The principle of preparing tin balls using the spraying process is to use high-speed airflow or centrifugal force to decompose molten tin into tiny droplets, which form tin balls during the cooling process.

[0038] S2. An insulating coating is applied to the surface of the conductive metal particles using a coating process, and then air-dried to form an insulating film. The thickness of the insulating film is 3%-25% of the diameter of the conductive metal particles.

[0039] In this step, an insulating coating with a thickness of 3%-25% of the diameter of the metal conductive particle spheres is coated on the surface of the metal conductive particle spheres using a chemical coating process or a physical coating process. The insulating coating is then air-dried at 50°C-80°C for 10-30 minutes, with the airflow speed controlled at 1m / s-2m / s. This process allows the insulating coating to cure and form an insulating film with uniform thickness, good adhesion, and stable mechanical properties. At this point, the insulating film encapsulates the metal conductive particle spheres.

[0040] The insulating film is made of one or more of resins, polymers, or thermoplastic polymers. For example, the resin can be epoxy resin, which has excellent mechanical strength, electrical insulation, and heat resistance; the polymer can be polyimide, which has excellent heat resistance, electrical insulation, and flexibility, making it suitable for high-temperature processes; the thermoplastic polymer can be polyethylene terephthalate, polyethylene, polypropylene, or ethylene-vinyl acetate copolymer, with polyethylene terephthalate being relatively inexpensive and possessing good electrical properties and mechanical strength. This allows the insulating film made from these materials to prevent short circuits in the conductive metal particles, to ensure the conductive metal particles conduct electricity along the Z-axis under specific pressure, and to protect the conductor from external environmental influences (such as oxidation); it also ensures the positioning and pressing effect of the conductor during bonding, i.e., stability during hot pressing.

[0041] If the thickness of the insulating film exceeds 25%, it may prevent the vertical surface from breaking during compression. If the insulating film does not break, it remains in an insulating state, and current cannot pass through, thus preventing the metal conductive sphere from conducting. If the thickness of the insulating film is less than 3%, it becomes too thin and may result in insufficient mechanical strength. Therefore, the thickness of the insulating film is controlled between 3% and 25% of the diameter of the metal conductive sphere. This allows the insulating film to easily break in the Z-axis direction and expose the metal conductive sphere under appropriate pressure and temperature conditions, enabling current to pass through the metal conductive sphere.

[0042] For example, when the insulating film material is selected from materials with a melting or softening temperature of around 150°C, such as polyethylene (PE), polypropylene (PP), or EVA, the insulating film softens when the temperature rises to around 150°C during the encapsulation process. Furthermore, due to the thinness of the insulating film, it is prone to cracking in the Z-axis direction under vertical pressure.

[0043] It is worth noting that: the Z-axis is perpendicular to the surface of the substrate and is consistent with the direction of the conductive path, which is the direction in which the insulating film breaks and exposes the metal conductive particles; the X-axis and Y-axis are both parallel to the surface of the substrate and are the directions in which insulation needs to be maintained between the metal conductive particles, i.e., the unbroken parts of the insulating film.

[0044] S3. Provide an insulating adhesive, place the metal conductive particle balls coated with the insulating film into the insulating adhesive, and stir to form an anisotropic conductive adhesive.

[0045] In this step, the insulating adhesive is made of modified epoxy resin, and the chemical composition of the insulating adhesive is different from that of the insulating film to prevent the insulating film from dissolving. The modified epoxy resin has an open time of 4 to 8 hours. The open time refers to the time window during which the adhesive can be operated after application but before it is fully cured. During this 4 to 8 hour period, the Mini / Micro LED chip can be inspected. When a defective product is detected, the insulating adhesive can be reactivated by heating to melt it. This allows the defective Mini / Micro LED chip to be easily removed and replaced with a good one without damaging the chip. This makes the repair process easier and less costly. Among them, epoxy resin is modified through specific chemical modification to form modified epoxy resin, and the modified epoxy resin does not contain volatile solvents, making it environmentally friendly and suitable for industrial applications; after curing, the modified epoxy resin has good conductivity and is suitable for replacing traditional solder paste in the photovoltaic industry; it can be cured by heating at 150℃ for 30 minutes, which is a low curing temperature; after curing, the modified epoxy resin can achieve a shear strength of more than 20 MPa against materials such as stainless steel, and has high bonding strength.

[0046] Metal conductive particles coated with an insulating film are placed into insulating adhesive and stirred using an appropriate stirring method to minimize agglomeration and ensure even distribution within the adhesive, forming anisotropic conductive adhesive. This adhesive not only allows Mini / Micro LED chips to be soldered onto the substrate pads but also enables targeted removal and replacement of Mini / Micro LED chips after reheating and remelting, reducing maintenance difficulty and costs.

[0047] It is worth noting that the uniformity mentioned in this application is relative uniformity, not absolute uniformity.

[0048] S4. Provide a hydrophobic nano-steel mesh with a plurality of steel holes and a substrate with a plurality of pads, and print the anisotropic conductive adhesive onto the pads through the hydrophobic nano-steel mesh.

[0049] In this step, a substrate with several pads is provided, and steel holes are made on a steel plate according to the distribution of the pads on the substrate to form a steel mesh. A hydrophobic nano-coating is coated on the steel mesh to prevent the anisotropic conductive adhesive from sticking to the steel holes, forming a hydrophobic nano-steel mesh. The hydrophobic nano-steel mesh is placed on the substrate, with the steel holes corresponding to the pads one by one. Then, the anisotropic conductive adhesive is added to the surface of the hydrophobic nano-steel mesh away from the pads. The anisotropic conductive adhesive is then evenly coated on the hydrophobic nano-steel mesh by a scraping method, so that the anisotropic conductive adhesive is printed onto the pads through the steel holes.

[0050] S5. Peel off the hydrophobic nano-steel mesh;

[0051] In this step, the hydrophobic nano-steel mesh is gradually separated from top to bottom or bottom to top to ensure that the anisotropic conductive adhesive filled on the pads remains intact and clear, facilitating the subsequent mounting of Mini / Micro LED chips onto the anisotropic conductive adhesive.

[0052] S6. Provide a Mini / Micro LED chip, mount the Mini / Micro LED chip onto an anisotropic conductive adhesive located on the pad, and apply heat and pressure to cause the insulating film of the anisotropic conductive adhesive to longitudinally rupture, exposing the metal conductive particles encased in the insulating film. This allows the metal conductive particles to contact the Mini / Micro LED chip and the pad respectively, forming a vertical conductive path. The insulating adhesive of the anisotropic conductive adhesive is then initially cured to obtain a Mini / Micro LED.

[0053] In this step, the Mini / Micro LED chip can be either unpackaged or packaged. The unpackaged or packaged Mini / Micro LED chip is mounted onto anisotropic conductive adhesive on the pads using mass transfer or SMT processes. Since the anisotropic conductive adhesive is directly applied to the pads via a hydrophobic nano-steel mesh, a separate dispensing process is unnecessary, saving process steps and reducing costs. Then, the unpackaged or packaged Mini / Micro LED chip on the anisotropic conductive adhesive is heated and pressurized to 120℃-250℃. This softens the insulating film of the anisotropic conductive adhesive, and under vertical mechanical pressure, excess insulating adhesive overflows, causing the insulating film to rupture in the Z-axis direction, exposing the metal conductive particles encased within the insulating film. These metal conductive particles are flattened under vertical mechanical force, arranging themselves in a neat row, and each metal conductive particle is positioned relative to the Mini / Micro LED pad. The LED chip and the pads form a conductive path. After heating for a certain period of time, the insulating adhesive of the anisotropic conductive adhesive begins to cure initially, resulting in a Mini / Micro LED.

[0054] In this embodiment, conductive metal particles with a diameter of 10μm-20μm are prepared by mechanical separation or spraying. An insulating coating is then applied to the surface of these particles, forming an insulating film with a thickness of 3%-25% of the particle diameter. This insulating film softens when heated to 120℃-250℃ and ruptures under vertical pressure, exposing the conductive metal particles. The conductive metal particles coated with the insulating film are then immersed in insulating adhesive and stirred to form anisotropic conductive adhesive. This adhesive secures the Mini / Micro LED chip, the conductive metal particles, and the pads, improving electrical connection stability. The anisotropic conductive adhesive is printed onto the pads using a hydrophobic nano-steel mesh. The Mini / Micro LED chip is then mounted onto the anisotropic conductive adhesive on the pads, and heating and pressurizing are applied to cause the insulating film of the anisotropic conductive adhesive to rupture longitudinally (Z-axis direction), exposing the conductive metal particles encased within the insulating film. This allows the conductive metal particles to bond with the Mini / Micro LED chip. The LED chip and the pads contact to form a vertical conductive path, allowing the insulating adhesive of the anisotropic conductive adhesive to initially cure, resulting in a Mini / Micro LED. This allows the Mini / Micro LED chip to light up normally when only two of the numerous conductive metal particles are connected, eliminating the need for all particles to be simultaneously conductive. This improves conductivity, reduces soldering difficulty, and enhances soldering quality. Furthermore, the insulating adhesive has an open time of 4-8 hours, allowing for easy removal and replacement of defective Mini / Micro LED chips without damaging the chip itself. This reduces repair difficulty and costs.

[0055] The present invention also discloses a second embodiment of a method for manufacturing Mini / Micro LEDs, comprising:

[0056] S10. Prepare metal conductive particle spheres by mechanical separation process or spraying process, wherein the diameter of the metal conductive particle spheres is 10μm-20μm;

[0057] In this step, the description of step S10 above refers to S1 of the first embodiment, and will not be repeated here.

[0058] S11. The conductive metal particles are immersed in a chemical solution using chemical deposition. An insulating coating is formed on the surface of the conductive metal particles through a chemical reaction. The insulating coating is then air-dried to form an insulating film; or...

[0059] The insulating coating material is deposited onto the surface of the metal conductive particles using physical vapor deposition to form an insulating coating, and the insulating coating is then air-dried to form an insulating film.

[0060] In this step, chemical deposition is a process that uses a suitable reducing agent to reduce metal ions in the plating solution and deposit them on the substrate surface. Specifically, conductive metal particles are immersed in a chemical solution, causing the metal ions in the insulating coating material to be reduced and deposited on the surface of the conductive metal particles, forming an insulating coating with a thickness of 3%-25% of the diameter of the conductive metal particles. The insulating coating is then air-dried at 50°C-80°C for 10-30 minutes, with the airflow speed controlled at 1m / s-2m / s, allowing the insulating coating to solidify and form an insulating film with uniform thickness, good adhesion, and stable mechanical properties. At this point, the insulating film encapsulates the conductive metal particles.

[0061] Physical vapor deposition (PVD) is a method that uses physical methods (such as evaporation and sputtering) to vaporize the coating material and deposit it onto the substrate surface to form a film. Specifically, in a vacuum environment, the insulating coating material is deposited onto the surface of conductive metal particles by evaporation or sputtering, forming an insulating coating with a thickness of 3%-25% of the diameter of the conductive metal particles. The insulating coating is then air-dried at 50°C-80°C for 10-30 minutes, with the airflow velocity controlled at 1m / s-2m / s, allowing the insulating coating to solidify and form an insulating film with uniform thickness, good adhesion, and stable mechanical properties. At this point, the insulating film encapsulates the conductive metal particles.

[0062] The insulating film not only allows the conductive metal particles to contact the pads of the Mini / Micro LED chip and the substrate to form vertical conductive paths, but also prevents short circuits caused by the conduction of two adjacent conductive metal particles in the X and Y axes, thus providing insulation. Because two adjacent conductive metal particles are insulated in the X and Y axes, even when multiple Mini / Micro LED chips are assembled, short circuits between adjacent chips will not occur. Therefore, when designing the holes in the hydrophobic nano-steel mesh, the diameter of the holes can be designed to be larger than the size of a single pad on the substrate (one pad corresponds to one Mini / Micro LED chip). Specifically, the diameter of the holes can be designed to accommodate the size of three pads. Since the diameter of the holes is twice that of holes accommodating one pad, it makes it easier for the anisotropic conductive adhesive to fill the pads through the holes during printing. This makes it more suitable for soldering small-pixel Mini / Micro LED chips and is applicable to ultra-high resolution Mini / Micro LEDs. For LED displays, the diameter of the steel hole can be designed to accommodate two, four, five, or six pads, etc. This embodiment does not impose a specific limit on the number of pads that the diameter of the steel hole can accommodate.

[0063] S12. Provide an insulating adhesive, and place metal conductive particles coated with the insulating film into the insulating adhesive. Stir at low speed to ensure that multiple metal conductive particles are evenly distributed in the insulating adhesive, forming an anisotropic conductive adhesive; or,

[0064] An insulating adhesive is provided. Metal conductive particles coated with the insulating film are placed into the insulating adhesive. The adhesive is stirred by a combination of rotation and revolution of a planetary mixer, so that multiple metal conductive particles are evenly distributed in the insulating adhesive to form an anisotropic conductive adhesive.

[0065] In this step, an insulating adhesive with a certain viscosity and consistency is provided. The consistency of the insulating adhesive is such that it ensures good adhesion while making it easier to disperse the metal conductive particles coated with the insulating film. The metal conductive particles coated with the insulating film are placed into the insulating adhesive and stirred at a low speed. The low-speed stirring method can reduce the aggregation and bubble generation of the metal conductive particles coated with the insulating film, which helps to make the metal conductive particles coated with the insulating film evenly distributed in the insulating adhesive. A dispersant can also be added to the insulating adhesive. The dispersant can reduce the interaction between the metal conductive particles coated with the insulating film and reduce agglomeration. The dispersant can be a surfactant or an organic solvent.

[0066] In addition to low-speed mixing, planetary mixing can also be used. The combined rotation and revolution of a planetary mixer can be used to mix the metal conductive particles coated with an insulating film, making the metal conductive particles coated with the insulating film more evenly distributed.

[0067] Because the current driving a single Mini / Micro LED chip is extremely small—typically less than 3-5 mA for each chip, and often only a fraction of a milliamp during normal operation—current can be established as long as a single conductive metal particle touches the pads of the Mini / Micro LED chip to the pads of the substrate. This allows the Mini / Micro LED chip to light up normally.

[0068] Therefore, under these low current requirements, even if some solder balls do not make complete contact during the soldering process, it will not affect the normal power supply and illumination of the chip. However, to ensure stability and reliability during long-term operation, it is necessary to ensure that all solder balls make good contact with the pads. Therefore, due to the viscosity and consistency of the adhesive, a small amount of adhesion may occur between the metal conductive particles coated with the insulating film. However, this small amount of adhesion does not affect the basic working principle of the metal conductive particles.

[0069] The steps in S4 include:

[0070] S13. A steel plate is provided, and steel holes are opened on the steel plate according to the pads of the substrate to form a steel mesh;

[0071] S14. Coat the steel mesh with a layer of nano-hydrophobic coating to obtain a hydrophobic nano-steel mesh;

[0072] S15. Provide a substrate with a plurality of pads, place the hydrophobic nano-steel mesh on the substrate and align it so that each of the steel holes is aligned with each of the pads respectively.

[0073] S16. Apply the anisotropic conductive adhesive to the side of the hydrophobic nano-steel mesh away from the pads, and uniformly coat the anisotropic conductive adhesive onto the hydrophobic nano-steel mesh, so that the anisotropic conductive adhesive is printed onto the pads through the steel holes.

[0074] In this step, the substrate can be either a circuit board or a glass substrate. The anisotropic conductive adhesive is printed using a stencil printer. First, a hydrophobic nano-stencil is prepared. Specifically, a steel plate is provided, and steel holes of the same size as the pads on the substrate are made on the steel plate, with the same distribution of the steel holes as the pads. A nano-hydrophobic coating is then coated onto the stencil to obtain the hydrophobic nano-stencil. The nano-hydrophobic coating can be a fluoride-based nano-coating, a silane-based nano-coating, or a nano-silica coating. For example, the fluoride-based nano-coating material is polytetrafluoroethylene or a perfluoroalkyl silane compound. Fluoride-based nano-coatings have extremely high hydrophobicity, with a water contact angle of 120°-150°, keeping the stencil surface clean and improving printing accuracy; they also have extremely low surface energy, preventing the anisotropic conductive adhesive from adhering to the steel holes in the hydrophobic nano-stencil, reducing clogging and extending the stencil's lifespan; and they exhibit excellent corrosion resistance and chemical stability. The silane nanocoating material is octyltriethoxysilane or methyltrichlorosilane, which has good hydrophobicity, with a water contact angle of 110°-130°, preventing anisotropic conductive adhesive from adhering to the steel pores of the hydrophobic nano-steel mesh; it has strong chemical bonding, stable coating, and wear resistance; it is easy to process and prepare, and has excellent adhesion, making it suitable for forming a long-term effective anti-stick layer on the steel mesh surface. The nano-silica coating has good hydrophobicity, and its performance can be enhanced through chemical modification; it has good wear resistance and thermal stability; it is low in cost, making it suitable for mass-produced steel mesh surface treatment.

[0075] After preparing the hydrophobic nano-stencil and the substrate, the substrate is first mounted on the fixture of the stencil printing machine. The fixture has adjustable supports and positioning pins to ensure accurate substrate positioning. Then, the hydrophobic nano-stencil is fixed to the frame of the printing machine. The printing machine's vision positioning system automatically detects the substrate's positioning marks (fiducial marks) for correction, aligning the substrate with the hydrophobic nano-stencil. Each stencil hole is aligned with each pad, meaning each stencil hole is directly below each pad. Finally, the substrate is fixed to the printing platform using vacuum adsorption or mechanical clamping. To prevent movement during printing, the squeegee (usually made of metal or polyurethane) in the stencil printer pushes the anisotropic conductive adhesive onto the surface of the hydrophobic nano-stencil, and applies it along the mesh at a set speed and pressure. The squeegee moves back and forth across the mesh, forcing the anisotropic conductive adhesive through the perforations on the mesh onto the substrate pads, ensuring a uniform height of the adhesive on the pads. Excess adhesive is collected by the squeegee and returned to the top of the mesh. After the mesh is fully filled, the stencil printer's control system slowly lifts the mesh, gradually separating it from the substrate. The squeegee speed is 20-100 mm / s, the squeegee pressure is 0.5-1.5 kg, and the printing environment should be kept clean and dry with humidity below 60%.

[0076] S17. Peel off the hydrophobic nano-steel mesh;

[0077] In this step, the description of step S18 above refers to S5 of the first embodiment, and will not be repeated here.

[0078] The steps in S6 include:

[0079] S18. The Mini / Micro LED chip is mounted onto the anisotropic conductive adhesive located on the pad using mass transfer or SMT processes.

[0080] S19. The Mini / MicroLED chip, which is mounted on the anisotropic conductive adhesive on the pad, is heated by a hot-pressing process, and pressure is applied longitudinally to the Mini / Micro LED chip. This softens the insulating film of the anisotropic conductive adhesive and causes it to crack in the Z-axis direction, exposing the metal conductive particles encased in the insulating film. The metal conductive particles are compressed and come into contact with the Mini / Micro LED chip and the pad respectively to form a vertical conductive path. This causes the insulating adhesive of the anisotropic conductive adhesive to initially cure, thus obtaining the Mini / Micro LED.

[0081] In this step, depending on the different mounting targets, either mass transfer technology or standard SMT technology is used.

[0082] When mounting unencapsulated Mini / Micro LED chips, a mass transfer process can be employed. Specifically, a transfer head with a flexible mold or electromagnetic adsorption head is used to pick up Mini / Micro LED chips in batches from a temporary carrier. A vision recognition system precisely aligns the picked-up Mini / Micro LED chips with the anisotropic conductive adhesive on the pads. The Mini / Micro LED chips are then released onto the anisotropic conductive adhesive. The alignment accuracy is ±1μm~2μm, the release pressure is 0.2MPa~1.0 MPa, and the temperature is 80°C~150°C. This mass transfer process enables the large-scale transfer and precise mounting of Mini / Micro LED chips from the carrier onto the anisotropic conductive adhesive on the pads, improving mounting efficiency, saving time, reducing costs, and ensuring high-quality electrical connections and mechanical strength.

[0083] When mounting pre-packaged Mini / Micro LED chips, standard SMT processes are used to mount the chips onto anisotropic conductive adhesive pads. Specifically, a pick-and-place machine uses a transfer head with a flexible mold or electromagnetic adsorption head to pick up the pre-packaged Mini / Micro LED chip. The pick-and-place machine's vision system precisely aligns the chip with the anisotropic conductive adhesive pads. The chip is then accurately placed onto the adhesive, ensuring high-quality electrical connections and mechanical strength.

[0084] The hot-pressing process involves applying pressure while heating. Specifically, the Mini / Micro LED chip, mounted on anisotropic conductive adhesive pads, is heated, and pressure is applied longitudinally to the chip. When the temperature reaches 120℃-250℃, the insulating film of the anisotropic conductive adhesive softens. Then, a uniform vertical pressure of 30N·m-100N·m is applied to the Mini / Micro LED chip via a planar pressure plate, causing the softened insulating film to rupture in the Z-axis direction, forming a first and second clearance opening. Since the insulating film encapsulates the metal conductive particles, when the insulating film ruptures, the metal conductive particles are exposed through the first and second clearance openings. The exposed metal conductive particles then interact with the Mini / Micro LED chip. The LED chip and the pads form a vertical conductive path. Since the insulating film is intact in the X and Y directions and is cured, it is protected from damage caused by external forces or environmental factors during use. This prevents short circuits caused by contact between two adjacent metal conductive particles in the X and Y directions, thus creating permanent insulation in the X and Y directions. Under pressure, this results in a tighter contact between the Mini / Micro LED chip, the metal conductive particles, and the pads, improving the stability of the electrical connection.

[0085] A Mini / Micro LED chip is soldered onto a pad, and the current driving a single Mini / Micro LED chip is very small. The maximum driving current of each Mini / Micro LED chip is usually less than 3-5mA, and in many cases, the driving current is only a few tenths of a milliamp during normal operation.

[0086] The current required to drive a single Mini / Micro LED chip is very small, and the anisotropic conductive adhesive on a pad contains multiple metal conductive particles. Since only one Mini / Micro LED chip is soldered onto a single pad, it is only necessary to ensure that one or two of the multiple metal conductive particles are conductive to enable the Mini / Micro LED chip to light up normally. It is not necessary for all the metal conductive particles to be conductive at the same time, which reduces the difficulty of soldering and improves the quality of soldering.

[0087] S20. The Mini / Micro LED chip is tested;

[0088] In this step, since the insulating adhesive requires 4-8 hours to fully cure, it is in a preliminary curing state during this period. Therefore, the insulating adhesive has an open time of 4-8 hours, during which the Mini / Micro LED chip can be tested.

[0089] S21. When the Mini / Micro LED chip is defective, the Mini / Micro LED chip is heated to dissolve the anisotropic conductive adhesive, the defective Mini / Micro LED chip is removed and replaced with a good Mini / Micro LED chip.

[0090] In this step, when a defective Mini / Micro LED chip is detected, the anisotropic conductive adhesive can be reactivated by heating to 120°C-250°C, causing the insulating adhesive to melt. Since the junction temperature of the Mini / Micro LED chip is 125°C-150°C, heating to 120°C-250°C not only remelts the insulating adhesive but also does not damage the Mini / Micro LED chip. After the insulating adhesive melts, the defective Mini / Micro LED chip can be easily removed and replaced with a good one. The insulating adhesive has an open time of 4-8 hours, allowing for repair and replacement of defective products during maintenance. This reduces maintenance difficulty, ensures a product yield close to 100%, avoids scrapping the entire substrate or display module, and minimizes maintenance costs. The insulating adhesive has an open time of 4 to 8 hours, which allows for the rework of defective Mini / Micro LED chips by heating during the open time, ensuring a product yield close to 100% and avoiding the scrapping of the entire substrate or display module. If problems are only discovered after curing, the entire substrate or display module may be scrapped. Rework during the open time greatly reduces production waste and material loss. This allows the production line to flexibly handle quality inspection and rework, reducing the risk of batch scrapping.

[0091] The open time of the insulating adhesive can also be adjusted by heating specific chemical materials in the insulating adhesive; for example, materials that extend the open time can be retarders or plasticizers; materials that accelerate curing can be catalysts or initiators; moisture-curing adhesives can also be used, so that the insulating adhesive gradually cures by absorbing moisture (humidity) from the air.

[0092] The Mini / Micro LED chips can be blue, green, or red. The maximum junction temperature for blue and green Mini / Micro LED chips is 150°C. At this temperature, even continuous heating for 30 minutes will not significantly affect their lifespan. The maximum junction temperature for red Mini / Micro LED chips is 125°C. Laboratory tests show that hot-pressing at 150°C for 30 minutes will not significantly affect the lifespan of red Mini / Micro LED chips. The heating temperature and time are coordinated: when heating to 250°C, the heating time is 1-8 seconds; when heating to 150°C, the heating time is 30 minutes to ensure that the anisotropic conductive adhesive is reactivated, melting the insulating adhesive without damaging the Mini / Micro LED chips. LED chips; however, heating temperatures exceeding 250°C and heating times exceeding 10 seconds may damage Mini / Micro LED chips.

[0093] In this embodiment, conductive metal particles with a diameter of 10μm-20μm are prepared by mechanical separation or spraying. An insulating coating is then applied to the surface of these particles, forming an insulating film with a thickness of 3%-25% of the particle diameter. This insulating film softens when heated to 120℃-250℃ and ruptures under vertical pressure, exposing the conductive metal particles. The conductive metal particles coated with the insulating film are then immersed in insulating adhesive and stirred to form anisotropic conductive adhesive. This adhesive secures the Mini / Micro LED chip, the conductive metal particles, and the pads, improving electrical connection stability. The anisotropic conductive adhesive is printed onto the pads using a hydrophobic nano-steel mesh. The Mini / Micro LED chip is then mounted onto the anisotropic conductive adhesive on the pads, and heating and pressurizing are applied to cause the insulating film of the anisotropic conductive adhesive to rupture longitudinally (Z-axis direction), exposing the conductive metal particles encased within the insulating film. This allows the conductive metal particles to bond with the Mini / Micro LED chip. The LED chip and the pads contact to form a vertical conductive path, allowing the insulating adhesive of the anisotropic conductive adhesive to initially cure, resulting in a Mini / Micro LED. This allows the Mini / Micro LED chip to light up normally when only one of the many conductive metal particles is conductive, eliminating the need for all particles to be conductive simultaneously. This reduces soldering difficulty and improves soldering quality. Furthermore, the insulating adhesive has an open time of 4-8 hours, allowing for easy removal and replacement of defective Mini / Micro LED chips without damaging the chip itself. This reduces repair difficulty and costs.

[0094] The above embodiments are only used to illustrate the technical solutions of this utility model, and are not intended to limit it. Under the concept of this utility model, the technical features of the above embodiments or different embodiments can also be combined, the steps can be implemented in any order, and there are many other variations of different aspects of this utility model as described above. For the sake of brevity, they are not provided in detail. Although this utility model has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that modifications can still be made to the technical solutions described in the foregoing embodiments, or equivalent substitutions can be made to some of the technical features. These modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions of the embodiments of this utility model.

Claims

1. A Mini / Micro LED, characterized in that, The Mini / Micro LED includes: A substrate, wherein the substrate is provided with multiple pads; Multiple anisotropic conductive adhesives are provided, with each anisotropic conductive adhesive being disposed on each of the pads. Multiple Mini / Micro LED chips, each of which is respectively disposed on each of the anisotropic conductive adhesives; Each of the anisotropic conductive adhesives includes an insulating adhesive layer and a plurality of insulating conductors. The insulating adhesive layer is connected to the substrate and the Mini / Micro LED chip respectively. The plurality of insulating conductors are disposed within the insulating adhesive layer and penetrate through the insulating adhesive layer to be electrically connected to the Mini / Micro LED chip and the pad respectively.

2. The Mini / Micro LED according to claim 1, characterized in that, The insulating conductor includes an insulating film and metal conductive particles. The insulating film covers the metal conductive particles. The top and bottom of the insulating film are respectively provided with a first clearance opening and a second clearance opening. The top and bottom of the metal conductive particles pass through the first clearance opening and the second clearance opening respectively and are electrically connected to the Mini / Micro LED chip and the pad.

3. The Mini / Micro LED according to claim 2, characterized in that, The diameter of the metal conductive spheres is 10μm-20μm.

4. The Mini / Micro LED according to claim 2, characterized in that, The material of the metal conductive granules is one of tin powder, silver powder, nickel powder, gold powder, tin alloy powder, copper powder, and aluminum powder.

5. The Mini / Micro LED according to claim 2, characterized in that, The insulating film is made of one of the following materials: resin, polymer, or thermoplastic polymer.

6. The Mini / Micro LED according to claim 2, characterized in that, The thickness of the insulating film is 3%-25% of the diameter of the metal conductive particle sphere.

7. The Mini / Micro LED according to claim 1, characterized in that, The insulating adhesive layer is made of modified epoxy resin.

8. The Mini / Micro LED according to claim 2, characterized in that, The pads include a positive pad and a negative pad. The Mini / Micro LED chip includes a positive pin and a negative pin. The positive pin is electrically connected to the positive pad through the metal conductive particle ball, and the negative pin is electrically connected to the negative pad through the metal conductive particle ball.

9. The Mini / Micro LED according to claim 1, characterized in that, The substrate can be a circuit board or a glass substrate.

10. The Mini / Micro LED according to claim 1, characterized in that, Multiple insulating conductors are uniformly distributed within the insulating adhesive layer.

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