Packaging structure and miniature LED device

Abstract

The utility model provides a packaging structure and a miniature LED device, and relates to the field of semiconductor display manufacturing. The packaging structure comprises a driving chip, a micro LED chip, a substrate layer and a boron nitride protection layer, the driving chip is provided with a bonding area; the micro LED chip is bonded to the bonding area; the substrate layer is connected to one side, deviating from the driving chip, of the micro LED chip; the boron nitride protection layer is arranged on the side, facing the micro LED chip, of the driving chip and covers the periphery of the bonding area. During laser lift-off processing, a laser beam irradiates the substrate layer and the periphery of the substrate layer from the side, away from the micro LED chip, of the substrate layer, and the boron nitride protection layer shields the driving chip, so that the laser beam is prevented from directly irradiating the part, except a bonding area, of the driving chip, the condition that a metal circuit on the driving chip is damaged at high temperature is improved, and the service life of the driving chip is prolonged. Therefore, the product yield is improved, the price cost is reduced, and the product performance is guaranteed.

Description

Technical Field

[0001] This utility model relates to the field of semiconductor display manufacturing, and in particular to a packaging structure and a micro LED device. Background Technology

[0002] Micro-LED (Micro Light Emitting Diode) technology, also known as LED miniaturization and matrixing technology, refers to the integration of high-density, tiny LEDs on a single chip, thereby enabling each pixel of an LED display to be addressable and individually driven, reducing the pixel level from millimeters to micrometers.

[0003] In the manufacturing process of micro LEDs, the LLO (Laser Lift-off) process is crucial. Many products exhibit driving abnormalities after the LLO process, such as short circuits or open circuits, leading to reduced product yield, increased costs, and adverse effects on product performance. Utility Model Content

[0004] In order to solve the problems existing in the prior art, one of the objectives of this utility model is to provide a packaging structure.

[0005] This utility model provides the following technical solution:

[0006] A packaging structure, comprising:

[0007] The driver chip has a bonding area;

[0008] The micro LED chip is bonded to the bonding region;

[0009] A substrate layer, connected to the side of the microLED chip opposite to the driver chip; and

[0010] A boron nitride protective layer is disposed on the side of the driver chip facing the micro LED chip and covers the periphery of the bonding area.

[0011] As a further optional embodiment of the packaging structure, the boron nitride protective layer is a boron nitride vapor-deposited film or a boron nitride coated film.

[0012] As a further optional embodiment of the encapsulation structure, the thickness of the boron nitride vapor-deposited film or the boron nitride coated film is 1 μm-10 μm.

[0013] As a further alternative to the packaging structure, the boron nitride protective layer is a boron nitride sheet, which is attached to the side of the driver chip facing the micro LED chip.

[0014] As a further alternative to the aforementioned packaging structure, the thickness of the boron nitride sheet is 10 μm-20 μm.

[0015] As a further optional embodiment of the packaging structure, the thickness of the boron nitride protective layer is greater than the thickness of the micro LED chip;

[0016] The encapsulation structure further includes an encapsulating adhesive layer, which is disposed in the bonding area and encapsulates the micro LED chip.

[0017] As a further optional embodiment of the packaging structure, the packaging structure further includes a first optical lens, which is embedded inside the boron nitride protective layer and located on the side of the encapsulating adhesive layer opposite to the driver chip.

[0018] As a further optional embodiment of the packaging structure, the packaging structure further includes a housing and a second optical lens, the housing being disposed on the side of the boron nitride protective layer away from the driver chip, and the second optical lens being disposed at the end of the housing away from the boron nitride protective layer.

[0019] As a further optional embodiment of the packaging structure, the packaging structure further includes a fluorescent layer embedded inside the boron nitride protective layer and located on the side of the encapsulating adhesive layer opposite to the driver chip.

[0020] Another objective of this invention is to provide a miniature LED device.

[0021] This utility model provides the following technical solution:

[0022] A miniature LED device includes the above-described packaging structure.

[0023] The embodiments of this utility model have the following beneficial effects:

[0024] During laser lift-off processing of the aforementioned packaging structure, the laser beam irradiates the substrate and its surroundings from the side of the substrate layer away from the micro LED chip. At this time, the boron nitride protective layer covering the bonding area shields the driver chip, preventing the laser beam from directly irradiating parts of the driver chip other than the bonding area. This mitigates damage to the metal circuitry on the driver chip at high temperatures, thereby improving product yield, reducing costs, and ensuring product performance.

[0025] To make the above-mentioned objectives, features and advantages of this utility model more apparent and understandable, preferred embodiments are described below in detail with reference to the accompanying drawings. Attached Figure Description

[0026] To more clearly illustrate the technical solutions of the embodiments of this utility model, the drawings used in the embodiments will be briefly introduced below. It should be understood that the following drawings only show some embodiments of this utility model and should not be regarded as a limitation on the scope. For those skilled in the art, other related drawings can be obtained based on these drawings without creative effort.

[0027] Figure 1 This diagram shows an overall structural schematic of a packaging structure provided by an embodiment of the present invention;

[0028] Figure 2 A schematic diagram of a packaging structure provided in another embodiment of the present invention is shown.

[0029] Explanation of key component symbols:

[0030] 100 - Driver chip; 110 - Bonding area; 120 - First pad; 200 - Micro LED chip; 300 - Substrate layer; 400 - Boron nitride protective layer; 500 - Heat dissipation metal plate; 510 - Second pad; 600 - Flexible circuit board; 700 - Encapsulating adhesive layer; 800 - First optical lens; 900 - Housing; 1000 - Second optical lens; 1100 - Phosphor layer. Detailed Implementation

[0031] The embodiments of this utility model are described in detail below. Examples of these embodiments are shown in the accompanying drawings, wherein the same or similar reference numerals denote the same or similar elements or elements having the same or similar functions throughout. The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain this utility model, and should not be construed as limiting this utility model.

[0032] It should be noted that when an element is said to be "fixed" to another element, it can be directly on the other element or there may be an intervening element. When an element is said to be "connected" to another element, it can be directly connected to the other element or there may be an intervening element. Conversely, when an element is said to be "directly" on another element, there is no intervening element. The terms "vertical," "horizontal," "left," "right," and similar expressions used in this document are for illustrative purposes only.

[0033] In this utility model, unless otherwise explicitly specified and limited, the terms "installation," "connection," "joining," and "fixing," etc., should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral part; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; they can refer to the internal communication of two components or the interaction between two components. Those skilled in the art can understand the specific meaning of the above terms in this utility model according to the specific circumstances.

[0034] Furthermore, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance or implicitly specifying the number of technical features indicated. Thus, a feature defined as "first" or "second" may explicitly or implicitly include one or more of that feature. In the description of this utility model, "a plurality of" means two or more, unless otherwise explicitly specified.

[0035] Unless otherwise defined, all technical and scientific terms used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this application belongs. The terminology used herein in the template description is for the purpose of describing particular embodiments only and is not intended to be limiting of the invention. The term "and / or" as used herein includes any and all combinations of one or more of the associated listed items.

[0036] The inventors of this application have discovered that during the manufacturing process of micro LEDs, many products exhibit driving abnormalities, such as short circuits or open circuits, after the LLO process. This is because the metal circuitry on the surface of the driver chip 100 is scanned by a laser, and the high temperature generated by the laser causes varying degrees of damage to the metal circuitry. Some metal circuitry is completely burned out, forming an open circuit and losing conductivity; others are partially burned out, forming a short circuit. These abnormalities further reduce product yield, increase costs, and adversely affect product performance.

[0037] To resolve the above issues, please refer to Figure 1 This embodiment provides a packaging structure, specifically a cost-effective micro-LED laser lift-off structure. The packaging structure includes a driver chip 100, a micro-LED chip 200, a substrate layer 300, and a boron nitride protective layer 400.

[0038] The driver chip 100 has a bonding region 110. Correspondingly, the micro LED chip 200 is bonded to the bonding region 110, and the substrate layer 300 is connected to the side of the micro LED chip 200 opposite to the driver chip 100.

[0039] In addition, a boron nitride protective layer 400 is disposed on the side of the driver chip 100 facing the micro LED chip 200 and covers the periphery of the bonding region 110.

[0040] During laser lift-off processing of the aforementioned packaging structure, the laser beam irradiates the substrate 300 and its surroundings from the side of the substrate 300 away from the micro LED chip 200. At this time, the boron nitride protective layer 400 covering the bonding region 110 shields the driver chip 100, preventing the laser beam from directly irradiating the portion of the driver chip 100 other than the bonding region 110. This mitigates the damage to the metal circuitry on the driver chip 100 at high temperatures, thereby improving product yield, reducing costs, and ensuring product performance.

[0041] If the metal circuitry on the surface of the driver chip 100 is protected by applying black adhesive to it, insufficient adhesive application precision often results in the black adhesive covering the surface of the substrate layer 300, making it difficult to peel off. Furthermore, during laser peeling, the gallium nitride layer connecting the micro-LED chip 200 and the substrate layer 300 gradually decomposes under laser irradiation. Liquid black adhesive can easily seep into the gap between the substrate layer 300 and the gallium nitride layer, covering the gallium nitride layer and making it difficult to clean. Moreover, the carbonization of the black adhesive at high temperatures severely affects the brightness of the micro-LED chip 200. Finally, the black adhesive needs to be cleaned off after laser peeling, making the process cumbersome.

[0042] In contrast, the aforementioned packaging structure, by providing a boron nitride protective layer 400 to protect the metal lines on the surface of the driver chip 100, reduces processes such as glue preparation, dispensing, and washing, thereby improving production efficiency. It also lowers material costs by eliminating the costs of dispensing machines, black glue, and washing solutions, and reduces the amount of glue used, thus reducing the package height. Furthermore, it improves production yield, allows for batch laser peeling without being limited by glue usage time, and increases both production volume and efficiency.

[0043] It should be noted that boron nitride is a crystal composed of nitrogen and boron atoms. The chemical composition of boron nitride is 43.6% boron and 56.4% nitrogen. It has four different variants: hexagonal boron nitride (HBN), rhombohedral boron nitride (RBN), cubic boron nitride (CBN), and wurtzite-type boron nitride (WBN).

[0044] Rhombohedral boron nitride is typically grayish-white or dark gray, with the specific color depending on its purity and preparation method. High-purity rhombohedral boron nitride is usually white, while industrial-grade rhombohedral boron nitride is dark gray. Rhombohedral boron nitride is a hard, wear-resistant ceramic material with excellent high-temperature stability; its physical and chemical properties also vary depending on its purity.

[0045] Wurtzite boron nitride is black in color. It is a hexagonal crystal with a diamond-like crystal structure and extremely high hardness, even exceeding that of diamond.

[0046] Pure cubic boron nitride is colorless and transparent, but due to the influence of raw material purity and synthesis process, cubic boron nitride can exhibit a variety of colors such as black, brown, amber, orange, and yellow.

[0047] Hexagonal boron nitride (BON) is a high-performance inorganic non-metallic material with a theoretical density of 2.27 g / cm³. BON crystals exhibit a layered structure similar to graphite. In powder form, it is loose, lubricated, hygroscopic, and lightweight, with a pure white appearance, hence the name "white graphite." Due to its unique crystal structure, BON possesses a range of special properties, such as high-temperature resistance, thermal shock resistance, corrosion resistance, lubricity, and electrical insulation.

[0048] In this embodiment, the boron nitride protective layer 400 is made of hexagonal boron nitride.

[0049] First, hexagonal boron nitride (BON) exhibits high heat resistance, maintaining structural and performance stability at high temperatures. BON only sublimates when heated to above 3000°C in nitrogen gas at 0.1 MPa, and its strength at 1800°C is twice that at room temperature, thus demonstrating excellent thermal shock resistance. This high-temperature resistance allows BON to maintain its reflective properties in high-temperature environments, making it suitable for laser reflection applications requiring high-temperature operation.

[0050] Secondly, hexagonal boron nitride has a high thermal conductivity of approximately 34 W / m·K, similar to that of stainless steel. This high thermal conductivity helps dissipate heat, reducing heat accumulation caused by laser irradiation and thus extending the material's lifespan.

[0051] Furthermore, hexagonal boron nitride possesses excellent electrical insulation and corrosion resistance, exhibiting good high-temperature insulation properties. High-purity hexagonal boron nitride can achieve a maximum volume resistivity of 10¹⁶–10¹⁸ Ω·m, remaining at 10⁴–10⁶ Ω·m even at 1000℃. This electrical insulation helps prevent laser energy conduction and reduces its impact on the reflecting surface. Simultaneously, hexagonal boron nitride exhibits good chemical stability, is not wetted by most molten metals, glasses, and salts, and possesses high resistance to acid, alkali, and molten metal corrosion.

[0052] In summary, the high heat resistance, high thermal conductivity, excellent electrical insulation, and corrosion resistance of hexagonal boron nitride (BON) give it significant advantages in laser reflection applications. These properties collectively ensure the stability and reliability of BON in laser reflection applications. Therefore, this embodiment uses a boron nitride protective layer 400 made of hexagonal boron nitride, which can effectively protect the portion of the driver chip 100 it covers, preventing damage to the metal circuitry on the surface of this portion of the driver chip 100 under laser irradiation.

[0053] In some embodiments, the boron nitride protective layer 400 is a boron nitride vapor-deposited film or a boron nitride coated film.

[0054] Understandably, a boron nitride vapor-deposited film can be formed by evaporating a hexagonal boron nitride film onto the surface of the driver chip 100. Alternatively, a boron nitride coated film can be formed by coating a hexagonal boron nitride film onto the surface of the driver chip 100.

[0055] The processing procedure is as follows:

[0056] The first step is to manufacture a driver chip 100 that matches the size of the micro LED chip 200, according to the product design requirements.

[0057] The second step involves adhering hexagonal boron nitride material to the surface of the driver chip 100 using a vapor deposition or powder spraying process, forming a boron nitride vapor-deposited film or a boron nitride coating film. During this process, the bonding area 110 of the driver chip 100 needs to be shielded to prevent the hexagonal boron nitride material from adhering and causing poor contact.

[0058] The boron nitride vapor-deposited film or boron nitride coating film has the characteristics of being white and opaque, high temperature resistant and fast thermal conductivity. At the same time, the white color has a reflective effect, which can effectively reflect the laser light shining on the surface of the driver chip 100, thereby protecting the circuit on the surface of the driver chip 100 from being damaged.

[0059] The third step is to bond the micro LED chip 200 and the driver chip 100 together using a flip-chip bonding device, so that the positive and negative lines of the micro LED chip 200 and the driver chip 100 are connected.

[0060] The fourth step involves using the bonded product from the third step for LLO laser lift-off. By setting the irradiation area through the laser program, the sapphire substrate and gallium nitride on top of the micro LED chip 200 are lifted off, thereby achieving an ultra-thin, high-performance product.

[0061] The fifth step involves using appropriate external force (such as mechanical force and pulling force) to separate the LLO-equipped micro LED chip 200 from the substrate 300, so that the substrate 300 detaches and does not remain on the micro LED chip 200.

[0062] The sixth step is to conduct a power-on test on the product obtained in the fifth step to display the effect, ultimately meeting the customer's requirements.

[0063] Furthermore, the thickness of the boron nitride vapor-deposited film or boron nitride coated film is 1μm-10μm.

[0064] Taking boron nitride vapor-deposited films as an example, ensuring a thickness of at least 1 μm guarantees sufficient protective effect. Conversely, limiting the thickness of boron nitride vapor-deposited films to no more than 10 μm avoids the time required for film formation, thus improving production efficiency.

[0065] Optionally, the thickness of the boron nitride vapor-deposited film or the boron nitride coated film can be 1 μm, 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm or any value between 1 μm and 10 μm.

[0066] In other embodiments, the boron nitride protective layer 400 is a boron nitride sheet attached to the side of the driver chip 100 facing the micro LED chip 200.

[0067] Specifically, a hexagonal boron nitride material is first processed into a sheet shape to obtain a boron nitride sheet. Then, before or after bonding the driver chip 100 and the micro LED chip 200, the boron nitride sheet is attached and fixed to the driver chip 100 with adhesive. The boron nitride sheet has an opening design to avoid obstructing the micro LED chip 200.

[0068] Furthermore, the thickness of the boron nitride sheet is 10μm-20μm.

[0069] Understandably, ensuring the boron nitride sheet thickness is no less than 10 μm ensures sufficient strength, preventing breakage during transfer and attachment after processing. Conversely, ensuring the boron nitride sheet thickness is no more than 20 μm avoids excessive overall product thickness, facilitating miniaturization and weight reduction.

[0070] Optionally, the thickness of the boron nitride sheet can be 10 μm, 11 μm, 12 μm, 13 μm, 14 μm, 15 μm, 16 μm, 17 μm, 18 μm, 19 μm, 20 μm or any value between 10 μm and 20 μm.

[0071] In some embodiments, the above-described packaging structure further includes a heat dissipation metal plate 500 and a flexible circuit board 600.

[0072] The heat dissipation metal plate 500 is located on the side of the driver chip 100 opposite to the micro LED chip 200, and the driver chip 100 is disposed on the heat dissipation metal plate 500. The driver chip 100 is provided with a first pad 120, and the heat dissipation metal plate 500 is provided with a second pad 510. The first pad 120 and the second pad 510 are connected by a gold wire.

[0073] In addition, one end of the flexible circuit board 600 is connected to the heat dissipation metal plate 500, and then electrically connected to the driver chip 100, while the other end of the flexible circuit board 600 is used to connect to external circuits.

[0074] Please see Figure 2 In some embodiments, the thickness of the boron nitride protective layer 400 is greater than the thickness of the micro LED chip 200.

[0075] In addition, the above-mentioned encapsulation structure also includes an encapsulating adhesive layer 700. The encapsulating adhesive layer 700 is disposed in the bonding region 110 and encapsulates the micro LED chip 200.

[0076] Understandably, after laser stripping, the boron nitride protective layer 400 can remain on the surface of the driver chip 100. Since the thickness of the boron nitride protective layer 400 is greater than the thickness of the micro-LED chip 200, a groove structure is formed on the aforementioned encapsulation structure corresponding to the bonding region 110. Based on this, encapsulating adhesive is applied within this groove structure, and the boron nitride protective layer 400 can block the adhesive, limiting its flow range. After the encapsulating adhesive cures, the resulting encapsulating adhesive layer 700 encapsulates the micro-LED chip 200, protecting it.

[0077] Preferably, the boron nitride protective layer 400 is made of boron nitride sheet, which is thicker and has a better effect in blocking the encapsulating adhesive.

[0078] Furthermore, the above-mentioned packaging structure also includes a first optical lens 800. The first optical lens 800 is embedded inside the boron nitride protective layer 400 and is located on the side of the encapsulating adhesive layer 700 opposite to the driver chip 100.

[0079] In use, the first optical lens 800 can focus the light emitted by the micro LED chip 200, making the beam more parallel. In addition, the first optical lens 800 is embedded inside the boron nitride protective layer 400. When installing the first optical lens 800, the boron nitride protective layer 400 can be used to position the first optical lens 800, reducing installation difficulty and improving installation accuracy.

[0080] Furthermore, the above-described packaging structure also includes a housing 900 and a second optical lens 1000. The housing 900 is disposed on the side of the boron nitride protective layer 400 away from the driver chip 100, and the second optical lens 1000 is disposed at the end of the housing 900 away from the boron nitride protective layer 400.

[0081] In use, the second optical lens 1000 can focus the parallel light after it has been focused by the first optical lens 800, adjust the focal length of the entire package structure, and thus control the imaging.

[0082] Specifically, the housing 900 is cylindrical and surrounds the micro LED chip 200, with its axis parallel to the optical path of the parallel light. One end of the housing 900 along its own axis is fixed to the boron nitride protective layer 400 with encapsulating adhesive, while the second optical lens 1000 is mounted on the other end of the housing 900.

[0083] Furthermore, the above-described encapsulation structure also includes a phosphor layer 1100. The phosphor layer 1100 is embedded inside the boron nitride protective layer 400 and is located on the side of the encapsulating adhesive layer 700 opposite to the driver chip 100.

[0084] When in use, the light of a specific wavelength emitted by the micro LED chip 200 shines on the fluorescent layer 1100 and excites the fluorescent material in the fluorescent layer 1100, which can produce other types of light, such as white light, warm light, etc.

[0085] Similar to the installation process of the first optical lens 800, the boron nitride protective layer 400 can position the fluorescent layer 1100, reducing the installation difficulty of the fluorescent layer 1100 and improving the installation accuracy of the fluorescent layer 1100.

[0086] For example, the thickness of the micro LED chip 200 is 2-6 μm, the thickness of the first optical lens 800 is 13 μm, and the phosphor layer 1100 is a white phosphor film with a thickness of 3 μm.

[0087] Understandably, the above-described packaging structure may include only one of the first optical lens 800 and the phosphor layer 1100. When the packaging structure includes the first optical lens 800, the thickness of the boron nitride protective layer 400 is greater than the sum of the thicknesses of the micro-LED chip 200 and the first optical lens 800. When the packaging structure includes the phosphor layer 1100, the thickness of the boron nitride protective layer 400 is greater than the sum of the thicknesses of the micro-LED chip 200 and the phosphor layer 1100.

[0088] Alternatively, the above-described packaging structure may also include both the first optical lens 800 and the phosphor layer 1100. In this case, the thickness of the boron nitride protective layer 400 is greater than the sum of the thicknesses of the micro LED chip 200, the first optical lens 800, and the phosphor layer 1100.

[0089] This embodiment also provides a micro LED device, including the above-described packaging structure, and thus possesses all the advantages of the above-described packaging structure, which will not be elaborated here.

[0090] In all examples shown and described herein, any specific values ​​should be interpreted as merely exemplary and not as limitations; therefore, other examples of exemplary embodiments may have different values.

[0091] It should be noted that similar labels and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0092] The embodiments described above are merely examples of several implementations of this utility model, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of this utility model. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of this utility model, and these modifications and improvements all fall within the protection scope of this utility model.

Claims

1. A packaging structure, characterized in that, include: The driver chip has a bonding area; The micro LED chip is bonded to the bonding region; A substrate layer is attached to the side of the micro LED chip opposite to the driver chip. as well as A boron nitride protective layer is disposed on the side of the driver chip facing the micro LED chip and covers the periphery of the bonding area.

2. The packaging structure according to claim 1, characterized in that, The boron nitride protective layer is a boron nitride vapor-deposited film or a boron nitride coated film.

3. The packaging structure according to claim 2, characterized in that, The thickness of the boron nitride vapor-deposited film or the boron nitride coated film is 1μm-10μm.

4. The packaging structure according to claim 1, characterized in that, The boron nitride protective layer is a boron nitride sheet, which is attached to the side of the driver chip facing the micro LED chip.

5. The packaging structure according to claim 4, characterized in that, The thickness of the boron nitride sheet is 10μm-20μm.

6. The packaging structure according to claim 1, characterized in that, The thickness of the boron nitride protective layer is greater than the thickness of the micro LED chip; The encapsulation structure further includes an encapsulating adhesive layer, which is disposed in the bonding area and encapsulates the micro LED chip.

7. The packaging structure according to claim 6, characterized in that, The packaging structure also includes a first optical lens, which is embedded inside the boron nitride protective layer and located on the side of the encapsulating adhesive layer away from the driver chip.

8. The packaging structure according to claim 7, characterized in that, The packaging structure further includes a housing and a second optical lens. The housing is disposed on the side of the boron nitride protective layer away from the driver chip, and the second optical lens is disposed at the end of the housing away from the boron nitride protective layer.

9. The packaging structure according to claim 6, characterized in that, The encapsulation structure further includes a fluorescent layer, which is embedded inside the boron nitride protective layer and located on the side of the encapsulating adhesive layer opposite to the driver chip.

10. A miniature LED device, characterized in that, The packaging structure includes any one of claims 1-9.

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