Inorganic packaging structure of deep ultraviolet LED and preparation method thereof

Abstract

According to the deep ultraviolet LED inorganic packaging structure and the preparation method thereof provided by the invention, the inorganic packaging structure of the deep ultraviolet LED avoids the problem of yellowing cracking failure of an organic material under ultraviolet irradiation in semi-inorganic packaging through a full-inorganic packaging design (without an organic adhesive), and guarantees the packaging reliability; compared with existing inorganic packaging, the lens surface metallization step is omitted, the technological process is greatly simplified, the production efficiency is improved, and the cost is reduced; meanwhile, the bottom plate of the packaging support and the box dam are integrally formed, the welding nugget portion formed through ultrafast laser induction is matched, the tight attachment and sealing effect of the optical lens and the box dam can be ensured, finally, efficient balance of deep ultraviolet LED packaging in reliability, production efficiency and economical efficiency is achieved, and the problem of the pain point of an existing packaging technology is effectively solved.

Description

Technical Field

[0001] This invention relates to the field of semiconductor optoelectronics, and more particularly to an inorganic packaging structure for deep ultraviolet LEDs. Background Technology

[0002] Deep ultraviolet (DUV) LEDs (Light-Emitting Diodes) are light sources with emission wavelengths between 200nm and 280nm. Thanks to their excellent sterilization and disinfection capabilities, they show great promise in fields such as medicine, food, and water treatment. Currently, their mainstream packaging methods are mainly divided into two categories: semi-inorganic packaging and inorganic packaging. The core difference between these two packaging methods lies in the fixing process between the lens and the packaging substrate. Different fixing processes directly determine their respective performance characteristics and applicable scenarios.

[0003] Semi-inorganic packaging uses traditional organic adhesives as the connecting medium, sealing and fixing the lens and the bracket through bonding. This process is mature and continues the traditional LED packaging technology system. Inorganic packaging, on the other hand, requires metallization soldering of the lens edges before laser bonding to connect the lens and bracket. The entire process does not use organic materials, making it a fully inorganic sealing process. From a performance and cost perspective, semi-inorganic packaging has significant advantages: it is a mature process, easy to mass-produce, and has significantly lower packaging costs. However, it has a key drawback—when the ultraviolet energy of a deep ultraviolet LED reaches a certain intensity, the organic adhesive gradually yellows and cracks, eventually leading to packaging failure. Inorganic packaging precisely overcomes this defect. Its fully inorganic structure gives it extremely high reliability and is completely unaffected by ultraviolet radiation. However, this process also has drawbacks such as relatively complex procedures, higher packaging costs, and lower production efficiency.

[0004] Therefore, there is an urgent need for an inorganic packaging structure for deep ultraviolet LEDs to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this invention is to provide an inorganic packaging structure for deep ultraviolet LEDs, which solves the technical problem that existing packaging structures for deep ultraviolet LEDs cannot simultaneously meet the requirements of reliability and economy.

[0006] To solve the above-mentioned technical problems, the present invention provides an inorganic packaging structure for deep ultraviolet LEDs, including a packaging bracket, an optical lens, and at least one deep ultraviolet LED chip. The packaging bracket includes a base plate and a dam. The dam is disposed around the outer periphery of the base plate and integrally formed with the base plate. A groove is formed on the upper surface of the base plate, and the deep ultraviolet LED chip is fixed to the bottom of the groove. The optical lens is disposed on the upper surface of the dam, and its edge is attached to the upper surface of the dam and completely covers the groove. In this process, the surface of the optical lens facing the groove and the upper surface of the dam are ionized and fused together by ultrafast laser technology to form a weld nugget.

[0007] Preferably, the minimum distance between the weld nugget and the opening edge of the groove is 2~10mm.

[0008] Preferably, the ratio of the orthographic projection area of ​​the weld nugget on the upper surface of the dam to the orthographic projection area of ​​the optical lens on the upper surface of the dam is 0.1 to 0.2.

[0009] Preferably, the deep ultraviolet LED chip has an emission wavelength of 200~400nm, and the thickness of the deep ultraviolet LED chip is less than or equal to the depth of the groove.

[0010] Preferably, the optical lens has a transmittance of ≥70% for light with a wavelength of 200~400nm.

[0011] Preferably, the side surface of the optical lens facing the groove is the welding surface, and the shape of the welding surface is a plane; the side surface of the optical lens away from the groove is the light-emitting surface, and the shape of the light-emitting surface is selected from any one of a plane, a hemisphere, an ellipsoid, a Fresnel sphere, and a polyhedral sphere.

[0012] Preferably, a Zener diode is also provided in the groove, and the Zener diode is connected in parallel with the deep ultraviolet LED chip; the Zener diode is unidirectional or bidirectional, and the turn-on voltage of the Zener diode is greater than the operating voltage of the deep ultraviolet LED chip.

[0013] Preferably, the material of the packaging bracket includes ceramic, metal, or ceramic with a metal layer on the surface, and the material of the optical lens includes glass or sapphire.

[0014] Accordingly, the present invention also provides a method for preparing an inorganic packaging structure for a deep ultraviolet LED as described in any of the above claims, the method comprising the following steps: S10, at least one deep ultraviolet LED chip is fixed to the bottom of the groove using a eutectic process; S20, an optical lens is placed on the upper surface of the dam, and an ultrafast laser process is used to induce the contact area between the side surface of the optical lens facing the groove and the upper surface of the dam, so that the area is ionized and fused together to form a weld nugget; the ultrafast laser process includes at least two laser beams, one laser beam is focused on the side surface of the optical lens facing the groove, and the other laser beam is focused on the upper surface of the dam.

[0015] Preferably, the wavelength of the laser is 600~1200nm, the frequency is 200kHz~2MHz, and the average power is greater than 10W.

[0016] The beneficial effects of this invention are as follows: Unlike the prior art, this invention provides an inorganic packaging structure for deep ultraviolet LEDs and its preparation method. The inorganic packaging structure for deep ultraviolet LEDs includes a packaging bracket, an optical lens, and at least one deep ultraviolet LED chip. The packaging bracket includes a base plate and a dam. The dam is arranged around the outer periphery of the base plate and integrally formed with the base plate. A groove is formed on the upper surface of the base plate, and the deep ultraviolet LED chip is fixed to the bottom of the groove. The optical lens is covered on the upper surface of the dam, and its edge is in contact with the upper surface of the dam and completely covers the groove. The side surface of the optical lens facing the groove and the upper surface of the dam are ionized and fused together by ultrafast laser technology to form a solder nugget. The inorganic packaging structure for deep ultraviolet LEDs provided by this invention avoids the problem of yellowing and cracking failure of organic materials under ultraviolet radiation in semi-inorganic packaging through a fully inorganic packaging design (without organic binders), ensuring packaging reliability. Compared with existing inorganic packaging, it eliminates the lens surface metallization step, greatly simplifying the process, improving production efficiency and reducing costs. At the same time, the base plate of the packaging bracket and the dam are integrally formed, and with the solder nugget formed by ultrafast laser induction, it can ensure a tight fit and sealing effect between the optical lens and the dam. Ultimately, it achieves a high-efficiency balance between reliability, production efficiency and economy in deep ultraviolet LED packaging, effectively solving the pain points of existing packaging technologies. Attached Figure Description

[0017] Figure 1 This is an axial schematic diagram of the inorganic packaging structure of the deep ultraviolet LED provided in the embodiment of the present invention; Figure 2 This is a top view of the inorganic packaging structure of the deep ultraviolet LED provided in the embodiment of the present invention; Figure 3 This is a front view of the inorganic packaging structure of the deep ultraviolet LED provided in an embodiment of the present invention; Figure 4 This is a method flow diagram of the inorganic packaging structure of deep ultraviolet LEDs provided in the embodiments of the present invention; In the attached diagram: 100—Inorganic packaging structure of deep ultraviolet LED; 10—Packaging bracket; 11—Base plate; 12—Dam; 101—Groove; 20—Deep ultraviolet LED chip; 30—Zener diode; 40—Optical lens; 50—Bond core. Detailed Implementation

[0018] The technical solutions of the present invention will be clearly and completely described below with reference to the embodiments of the present invention. Obviously, the described embodiments are only some embodiments of the present invention, and not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0019] To address the shortcomings of existing technologies, this invention provides a deep ultraviolet (DUV) LED inorganic packaging structure and its fabrication method. This structure not only overcomes the defects of existing semi-inorganic packaging (organic materials are susceptible to UV damage and failure) and inorganic packaging (complex processes and high costs), but also achieves multiple advantages such as UV resistance, water resistance, simple processing, and controllable costs. In particular, compared with existing inorganic packaging processes, it eliminates the need for metallization of the lens surface, significantly simplifying the process and improving production efficiency. This structure can reliably protect the DUV LED chip, effectively expanding its application in fields with high reliability requirements such as medical disinfection and water treatment.

[0020] Please see Figures 1 to 3 , Figure 1 This is an axial schematic diagram of the inorganic packaging structure 100 of the deep ultraviolet LED provided in an embodiment of the present invention; Figure 2 This is a top view of the inorganic packaging structure 100 of the deep ultraviolet LED provided in this embodiment of the invention; Figure 3 This is a front view of the inorganic packaging structure 100 for deep ultraviolet LEDs provided in an embodiment of the present invention. The inorganic packaging structure 100 for deep ultraviolet LEDs includes a packaging bracket 10, an optical lens 40, and at least one deep ultraviolet LED chip 20. The packaging bracket 10 includes a base plate 11 (with internal metal wiring) and a dam 12. The dam 12 is arranged around the outer periphery of the base plate 11 and is integrally formed with the base plate 11. A groove 101 is formed on the upper surface of the base plate 11, and the deep ultraviolet LED chip 20 is fixed to the bottom of the groove 101. The optical lens 40 is covered on the upper surface of the dam 12, and its edge is in contact with the upper surface of the dam 12 and completely covers the groove 101. In this process, the surface of the optical lens 40 facing the groove 101 and the upper surface of the dam 12 are ionized and fused together by an ultrafast laser process to form the weld nugget 50.

[0021] Specifically, the inorganic packaging structure 100 for deep ultraviolet LEDs provided by this invention, through its all-inorganic design (without organic binders), avoids the problem of yellowing and cracking of organic materials under ultraviolet radiation in semi-inorganic packaging, ensuring the reliability of the packaging against ultraviolet radiation. Compared with existing inorganic packaging, there is no need to metallize the optical lens 40. Combined with the process of forming the solder nugget 50 by ultrafast laser-induced ionization fusion, the process is greatly simplified, production efficiency is improved, and costs are reduced. At the same time, the base plate 11 of the packaging bracket 10 and the dam 12 are integrally formed. Together with the solder nugget 50, it can ensure that the optical lens 40 and the dam 12 are tightly attached, achieving a good sealing and waterproof effect. Ultimately, it provides reliable protection for the deep ultraviolet LED chip 20, helping to expand its application in fields with high reliability requirements.

[0022] In this embodiment of the invention, the shortest distance between the solder nugget 50 and the opening edge of the groove 101 is 2~10mm. This shortest distance effectively avoids the groove 101 area where the deep ultraviolet LED chip 20 is located, preventing damage to the deep ultraviolet LED chip 20 from heat or energy generated during ultrafast laser welding, thus ensuring stable operation of the deep ultraviolet LED chip 20. It also provides sufficient space for the solder nugget 50 to ensure structural integrity and strong connection, thereby improving the sealing and bonding effect between the optical lens 40 and the dam 12. Simultaneously, this distance range takes into account the compactness of the packaging structure, avoiding redundancy in packaging volume due to excessive spacing, ultimately further optimizing the reliability and practicality of the deep ultraviolet LED inorganic packaging structure.

[0023] In this embodiment of the invention, the ratio of the orthographic projection area of ​​the solder nugget 50 on the upper surface of the dam 12 to the orthographic projection area of ​​the optical lens 40 on the upper surface of the dam 12 is 0.1 to 0.2. This ratio ensures that the solder nugget 50 has sufficient area to achieve a stable connection between the optical lens 40 and the dam 12, guaranteeing the sealing reliability of the encapsulation structure. It also prevents the solder nugget 50 from being too large and occupying too much of the effective projection area of ​​the optical lens 40, reducing obstruction of deep ultraviolet light emission and ensuring the light extraction efficiency of the lens. Furthermore, this ratio precisely balances the requirements of connection strength and light extraction performance, avoiding connection failure due to an excessively small ratio or affecting light efficiency due to an excessively large ratio, thus further optimizing the overall performance of the deep ultraviolet LED inorganic encapsulation structure.

[0024] In this embodiment of the invention, the deep ultraviolet LED chip 20 can be a single chip or a combination of multiple chips. The emission wavelength of the deep ultraviolet LED chip 20 is 200~400nm (preferably a short-wave ultraviolet UVC chip of 200~280nm), and the thickness of the deep ultraviolet LED chip 20 is less than or equal to the depth of the groove 101.

[0025] Specifically, the deep ultraviolet LED chip 20, with its emission wavelength of 200~400nm, can accurately cover the functional requirements of deep ultraviolet radiation, ensuring the realization of core performances such as sterilization and disinfection. The design that the thickness of the deep ultraviolet LED chip 20 is less than or equal to the depth of the groove 101 not only allows the deep ultraviolet LED chip 20 to be completely contained within the groove 101, avoiding damage to the deep ultraviolet LED chip 20 caused by external force or the pressing of the optical lens 40, but also ensures a tight fit between the optical lens 40 and the upper surface of the dam 12, without affecting the formation of the solder core 50 and the sealing effect. Ultimately, the comprehensive performance of the deep ultraviolet LED inorganic packaging structure is optimized from multiple dimensions of adaptability, functionality and protection.

[0026] In this embodiment of the invention, the optical lens 40 has a transmittance of ≥70% for light with wavelengths of 200~400nm. This transmittance design effectively reduces the loss of deep ultraviolet light during lens transmission, ensuring efficient emission of deep ultraviolet light emitted by the deep ultraviolet LED chip 20. This high transmittance design ensures that the deep ultraviolet LED still possesses sufficient ultraviolet light intensity after packaging, meeting the energy requirements of ultraviolet light in applications such as sterilization, disinfection, and water treatment. Furthermore, this transmittance index is compatible with the emission wavelength of the deep ultraviolet LED chip 20, further improving the light efficiency of the packaging structure and providing crucial support for the stable application of the product in fields with high reliability requirements.

[0027] In this embodiment of the invention, the side surface of the optical lens 40 facing the groove 101 is a welding surface, and the shape of the welding surface is a plane; the side surface of the optical lens 40 away from the groove 101 is a light-emitting surface, and the shape of the light-emitting surface is selected from any one of a plane, a hemisphere, an ellipsoid, a Fresnel sphere, and a polyhedral sphere.

[0028] Specifically, the optical lens 40 has a flat welding surface facing the groove 101, ensuring close contact with the upper surface of the dam 12. This provides a stable interface for ultrafast laser welding, facilitating the formation of a structurally complete and firmly connected weld nugget 50, thus improving the sealing and reliability of the packaging. Simultaneously, the light-emitting surface adopts a variety of shapes, including planar and hemispherical, allowing for flexible adaptation to different application scenarios' requirements for light emission angle and intensity distribution, optimizing the deep ultraviolet light emission effect. This design works synergistically to improve both welding stability and optical performance, further enhancing the practicality and adaptability of the deep ultraviolet LED inorganic packaging structure.

[0029] In this embodiment of the invention, a Zener diode 30 is also provided in the groove 101, and the Zener diode 30 is connected in parallel with the deep ultraviolet LED chip 20; the Zener diode 30 is a unidirectional or bidirectional type, and the turn-on voltage of the Zener diode 30 is greater than the operating voltage of the deep ultraviolet LED chip 20.

[0030] Specifically, the Zener diode 30 has a turn-on voltage greater than the operating voltage of the deep ultraviolet LED chip 20. It can conduct and discharge voltage when an overvoltage occurs in the circuit, preventing the chip from being damaged by overvoltage and effectively protecting the safety of the deep ultraviolet LED chip 20. At the same time, the Zener diode 30 supports both unidirectional and bidirectional conduction, which can adapt to the protection requirements of different circuit scenarios and improve the circuit adaptability of the package structure.

[0031] In this embodiment of the invention, the material of the encapsulation bracket 10 includes ceramic, metal or ceramic with a metal layer on the surface, and the material of the optical lens 40 includes glass or sapphire.

[0032] Specifically, the encapsulation bracket 10 is made of ceramic, metal, or ceramic with a metal layer on the surface, while the optical lens 40 is made of glass or sapphire. Due to the characteristics of all-inorganic materials, it can withstand deep ultraviolet irradiation and avoid material aging. It also provides crucial support from the perspective of the solder nugget 50 formation. The metal or ceramic bracket with a metal layer on the surface can efficiently absorb ultrafast laser energy. Working synergistically with the glass / sapphire lens, which is also adapted to laser technology, it helps the contact area of ​​the two to quickly ionize and fuse, ensuring a dense structure and strong connection of the solder nugget 50. At the same time, ceramic materials have insulation properties, metal materials have excellent thermal conductivity, and ceramic with a metal layer on the surface can balance insulation and thermal conductivity, adapting to different heat dissipation and insulation requirements. The high light transmittance of glass and sapphire also ensures the deep ultraviolet light emission efficiency. This material combination not only lays the foundation for the stable formation of the solder nugget 50 but also optimizes the encapsulation effect from multiple dimensions, including structural stability, functional adaptability, and optical performance, further improving the reliability and practicality of the deep ultraviolet LED inorganic encapsulation structure.

[0033] Please see Figure 4 The present invention also provides a method for preparing an inorganic encapsulation structure 100 for a deep ultraviolet LED as described in any of the above claims, the method comprising the following steps: S10, at least one deep ultraviolet LED chip 20 is fixed to the bottom of the groove 101 by a eutectic process; wherein, the eutectic process can achieve a firm connection between the deep ultraviolet LED chip 20 and the packaging bracket 10 and efficient heat dissipation, ensuring the stability of chip operation. Specifically, after step S10 is completed, it also includes: connecting a Zener diode 30 in parallel next to the deep ultraviolet LED chip 20; wherein, connecting the deep ultraviolet LED chip 20 and the Zener diode 30 in parallel can form targeted overvoltage protection, further protecting the chip safety.

[0034] S20, the optical lens 40 is placed on the upper surface of the dam 12, and an ultrafast laser process is used to induce the contact area between the side surface of the optical lens 40 facing the groove 101 and the upper surface of the dam 12, so that the area is ionized and fused together to form the weld nugget 50; the ultrafast laser process includes at least two laser beams, one laser beam is focused on the side surface of the optical lens 40 facing the groove 101, and the other laser beam is focused on the upper surface of the dam 12.

[0035] In step S20, a process design employing at least two laser beams focused on the surfaces of the optical lens 40 and the dam 12 respectively can precisely induce ionization and fusion of the contact area (narrow region) between the two to form the solder nugget 50. This eliminates the need for metallization of the optical lens 40, significantly simplifying the process and improving production efficiency, while ensuring a tight connection and reliable sealing of the solder nugget 50. The overall fabrication process is simple, efficient, and cost-controllable, and can stably produce highly reliable packaging structures, providing strong support for the large-scale application of deep ultraviolet LEDs.

[0036] In step S20, the wavelength of the laser is 600~1200nm, the frequency is 200kHz~2MHz, and the average power is greater than 10W.

[0037] Specifically, a suitable wavelength and sufficient average power can rapidly induce ionization and fusion in the contact area, ensuring a dense structure and strong connection in the weld nugget 50. A frequency of 200kHz to 2MHz meets the efficiency requirements of mass production while avoiding thermal damage to the deep ultraviolet LED chip 20 due to excessive energy concentration. This parameter design provides stable and reliable energy support for the ultrafast laser welding process, ensuring both sealing performance and improved production efficiency without the need for lens metallization. This further guarantees the fabrication quality and large-scale application potential of the deep ultraviolet LED inorganic packaging structure.

[0038] In summary, unlike existing technologies, the deep ultraviolet LED inorganic packaging structure and its fabrication method provided by this invention achieve a breakthrough in addressing the pain points of existing packaging technologies through innovative design. Structurally, it employs a one-piece molded packaging bracket 10 combined with all-inorganic materials, along with an ultrafast laser-induced solder nugget 50. This avoids the problem of organic materials failing under ultraviolet irradiation in semi-inorganic packaging and eliminates the need for the lens metallization step in existing inorganic packaging. In terms of fabrication, it uses a eutectic process to fix the chip and dual-beam laser precision welding of the optical lens 40, coupled with optional Zener diode 30 overvoltage protection. This not only significantly simplifies the process, improves production efficiency, and reduces costs, but also ensures the UV resistance, sealing performance, and reliability of the packaging structure. Ultimately, this invention achieves a balance between reliability, economy, and production efficiency in deep ultraviolet LED packaging, providing strong support for its large-scale application in high-end fields such as medical disinfection and water treatment.

[0039] It should be noted that all the above embodiments belong to the same inventive concept, and the descriptions of each embodiment have different focuses. Where the description in a particular embodiment is not detailed, please refer to the description in other embodiments.

[0040] The above embodiments merely illustrate implementation methods of the present invention, and while the descriptions are relatively specific and detailed, they should not be construed as limiting the scope of the invention patent. It should be noted that those skilled in the art can make various modifications and improvements without departing from the concept of the present invention, and these all fall within the protection scope of the present invention. Therefore, the protection scope of this invention patent should be determined by the appended claims.

Claims

1. An inorganic encapsulation structure of a deep ultraviolet LED, characterized by, The package bracket, the optical lens and at least one deep ultraviolet LED chip are included, the package bracket includes a bottom plate and a dam which is arranged around the periphery of the bottom plate and is integrally formed with the bottom plate, an upper surface of the bottom plate is provided with a groove, and the deep ultraviolet LED chip is fixed to the bottom of the groove; the optical lens is arranged on the upper surface of the dam, the edge thereof is attached to the upper surface of the dam, and the optical lens completely covers the groove; The side surface of the optical lens facing the groove and the upper surface of the dam are ionized and fused with each other by an ultrafast laser process to form a nugget part.

2. The inorganic encapsulation structure of a DUV LED according to claim 1, wherein, The shortest distance between the nugget part and the opening edge of the groove is 2-10 mm.

3. The inorganic encapsulation structure of a DUV LED of claim 1, wherein, The ratio of the area of the projection of the nugget part on the upper surface of the dam to the area of the projection of the optical lens on the upper surface of the dam is 0.1-0.

2.

4. The inorganic encapsulation structure of a DUV LED of claim 1, wherein, The light-emitting wavelength of the deep ultraviolet LED chip is 200-400 nm, and the thickness of the deep ultraviolet LED chip is less than or equal to the depth of the groove.

5. The inorganic encapsulation structure of a DUV LED of claim 4, wherein, The transmittance of the optical lens to light with a wavelength of 200-400 nm is greater than or equal to 70%.

6. The inorganic encapsulation structure of a DUV LED of claim 5, wherein, The side surface of the optical lens facing the groove is a welding surface, and the shape of the welding surface is a plane; the side surface of the optical lens away from the groove is a light-emitting surface, and the shape of the light-emitting surface is selected from any one of a plane, a hemispherical surface, an ellipsoidal surface, a Fresnel spherical surface and a polyhedral spherical surface.

7. The inorganic encapsulation structure of a DUV LED of claim 1, wherein, A Zener diode is further arranged in the groove, the Zener diode is connected in parallel with the deep ultraviolet LED chip, the Zener diode is of a unidirectional conduction type or a bidirectional conduction type, and the turn-on voltage of the Zener diode is greater than the working voltage of the deep ultraviolet LED chip.

8. The inorganic encapsulation structure of a DUV LED of claim 1, wherein, The material of the package bracket includes ceramic, metal or ceramic provided with a metal layer on the surface, and the material of the optical lens includes glass or sapphire.

9. A method of producing an inorganic encapsulation structure of a deep ultraviolet LED as claimed in any one of claims 1 to 8, characterized by, The method includes the following steps: S10, at least one deep ultraviolet LED chip is fixed to the bottom of the groove by a eutectic process; S20, the optical lens is placed on the upper surface of the dam, and an ultrafast laser process is used to induce the contact area between the side surface of the optical lens facing the groove and the upper surface of the dam, so that the contact area is ionized and fused with each other to form the nugget part; the ultrafast laser process includes at least two lasers, the focal point of one of the lasers is focused on the side surface of the optical lens facing the groove, and the focal point of the other laser is focused on the upper surface of the dam.

10. The method of claim 9, wherein the method further comprises: The wavelength of the laser is 600-1200 nm, the frequency is 200 KHZ-2 MHZ, and the average power is greater than 10 W.

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