High-efficiency ultraviolet light source and packaging method thereof

Abstract

The invention discloses a high-efficiency ultraviolet light source and a packaging method thereof. The ultraviolet light source comprises a substrate, an ultraviolet LED chip and a light window, an inner electrode layer and a welding layer are arranged on the upper surface of the substrate, and the ultraviolet LED chip is welded on the inner electrode layer; the light window comprises a lens and an integrated tube shell; the integrated tube shell comprises a surrounding shell arranged around the ultraviolet LED chip and a reflection cup located on the inner side of the surrounding shell and arranged around the ultraviolet LED chip. A horizontal part extending outwards is arranged at the lower end of the surrounding shell, and the bottom surface of the horizontal part and the welding layer of the substrate are sealed and welded together; the upper surface of the reflection cup is constructed to be a reflection surface which is gradually raised from inside to outside, and a reflection layer is arranged on the reflection surface; the surrounding shell and the reflection cup are integrally formed, a downward-concave welding flux groove is formed in the connecting position of the surrounding shell and the reflection cup, a welding flux ring is arranged in the welding flux groove, and the edge of the lower surface of the lens is pressed on the welding flux ring and welded and fixed. The invention has the advantages of low light loss and high light extraction efficiency.

Description

Technical Field

[0001] This invention relates to the field of LED packaging technology, and in particular to a high-efficiency ultraviolet light source and its packaging method. Background Technology

[0002] Deep ultraviolet (DUV) LEDs, employing the AlGaN luminescent material system, exhibit a strong transverse magnetic (TM) mode of emission when the wavelength is below 280nm, resulting in high light intensity on the chip's sides. However, the high energy of DUV light is highly destructive to traditional organic encapsulation materials (such as silicone and epoxy resin), causing aging, yellowing, and even cracking. This leads to serious problems for DUV LEDs using traditional organic encapsulation, including low reliability and short lifespan.

[0003] To address the aforementioned issues, "all-inorganic packaging," which enables high reliability and long lifespan, has become the main technological approach for deep ultraviolet LED packaging. Early all-inorganic packaging often employed three-dimensional support structures or three-dimensional lens structures. However, due to the processing characteristics of inorganic materials such as quartz glass, the fabrication of three-dimensional structures is difficult and extremely costly, making it difficult to achieve low-cost, high-yield mass production.

[0004] Currently, a technical solution based on sintering a planar lens and a metal housing using a glass solder ring has emerged in the industry. This solution involves sintering and fixing a planar quartz light window with glass solder to form a lens assembly, and then laser-sealing the metal light window to the substrate. Because glass solder and laser sealing technology can achieve extremely high hermeticity, this process has become an effective solution for the mass production of all-inorganic deep ultraviolet LEDs.

[0005] However, the existing planar light window combined with a metal casing packaging structure still has significant defects in optical performance: First, besides achieving a high extraction rate for forward-emitting light, a large proportion of the relatively oblique light emitted by the chip undergoes total internal reflection or Fresnel reflection when it reaches the flat glass interface, resulting in absorption loss as it is reflected back into the package. Second, combined with the aforementioned TM mode luminescence characteristics, the even more oblique light emitted from the side of the deep ultraviolet LED chip (side light) directly illuminates the sidewall of the metal casing, thus being absorbed and lost by the sidewall material. In summary, although the existing all-inorganic packaging structure solves the problems of hermeticity and lifespan, its low light extraction efficiency (LEE) severely limits the overall optical power output of the device.

[0006] Therefore, it is necessary to further improve and refine the existing technology to overcome these shortcomings, and this invention is made based on this situation. Summary of the Invention

[0007] The object of the present invention is to overcome the deficiencies of the prior art and provide an ultraviolet light source with less light loss and high light extraction efficiency and its packaging method.

[0008] The present invention can be realized through the following technical solutions:

[0009] To solve the above technical problems, the present invention provides a high-efficiency ultraviolet light source, including a substrate, an ultraviolet LED chip, and an optical window; an inner electrode layer is provided on the upper surface of the substrate, and a welding layer is provided around the inner electrode layer, and the ultraviolet LED chip is welded on the inner electrode layer; the optical window includes a lens directly above the ultraviolet LED chip and an integral housing for supporting the lens; the integral housing includes a surrounding shell surrounding the ultraviolet LED chip and a reflecting cup located inside the surrounding shell and surrounding the ultraviolet LED chip; the lower end of the surrounding shell is provided with a horizontally extending portion, and the bottom surface of the horizontally extending portion is sealed and welded to the welding layer of the substrate; the upper surface of the reflecting cup is configured as a reflecting surface that gradually rises from the inside to the outside, and a reflecting layer is provided on the reflecting surface; the surrounding shell and the reflecting cup are integrally formed, and a concave solder groove is provided at the connection between the two, and a solder ring is provided in the solder groove, and the edge of the lower surface of the lens is pressed on the solder ring and welded and fixed.

[0010] To further solve the technical problems to be solved by the present invention, in the high-efficiency ultraviolet light source provided by the present invention, the height h2 of the outer side wall of the solder groove is greater than the height h1 of its inner side wall.

[0011] To further solve the technical problems to be solved by the present invention, in a high-efficiency ultraviolet light source provided by the present invention, the inner end radius of the solder groove is r, the outer end radius of the solder groove is R, and the radius of the lens is R0, and the three satisfy the following relationship: R0 > (r + R) / 2.

[0012] To further solve the technical problems to be solved by the present invention, in a high-efficiency ultraviolet light source provided by the present invention, before the lens is pressed, the height h3 of the solder ring is higher than the height h2 of the outer side wall of the solder groove; and before the lens is pressed, the inner diameter of the solder ring is r1, the outer diameter of the solder ring is R1, and the following relationship is satisfied: (r + R0) / 2 ≤ r1 < R0, and R1 > R.

[0013] To further solve the technical problems to be solved by the present invention, in a high-efficiency ultraviolet light source provided by the present invention, it further includes a light confinement layer, and the light confinement layer uses an optical coupling medium with a refractive index greater than that of air; the light confinement layer is configured as an inverted trapezoidal structure that wraps the ultraviolet LED chip, or the light confinement layer is filled in the cavity formed by the reflecting cup and the lens.

[0014] To further address the technical problem addressed by this invention, a high-efficiency ultraviolet light source is provided in which the light confinement layer has an inverted trapezoidal structure, and the bottom surface of the lens is pressed against the upper end of the light confinement layer; a surface-active material is sprayed onto the bottom surface of the lens, and the surface-active material is distributed within region A defined by the reflector cup as a mask; the inverted trapezoidal light confinement layer is formed by a convex light confinement layer medium dotted on the ultraviolet LED chip under the pressing action of the bottom surface of the lens.

[0015] To further address the technical problem to be solved by this invention, in a high-efficiency ultraviolet light source provided by this invention, if the light confinement layer has an inverted trapezoidal structure, the angle β between the side of the light confinement layer and the upper surface of the substrate is less than 75°.

[0016] To further address the technical problem to be solved by the present invention, the present invention provides a high-efficiency ultraviolet light source in which an upwardly protruding limiting ring is provided on the upper surface of the substrate or the welding layer. The limiting ring is located below the inner end of the reflector cup, and the upper end of the limiting ring abuts against the lower surface of the reflector cup.

[0017] To further address the technical problem addressed by this invention, the present invention provides a high-efficiency ultraviolet light source in which the reflecting surface of the reflector cup is inclined or curved; if the reflecting surface of the reflector cup is inclined, the angle γ between the inclined surface of the reflector cup and the substrate is in the range of 20°-60°.

[0018] This invention can also be achieved through the following technical solutions:

[0019] A packaging method for a high-efficiency ultraviolet light source as described above includes the following steps:

[0020] Step S1: Provide a substrate, and weld and fix ultraviolet LED chips on the inner electrode layer on the upper surface of the substrate to form a substrate assembly;

[0021] Step S2: Provide a lens and an integrally formed shell, the integral shell including a housing, a reflector cup and a recessed solder groove located at the junction of the two;

[0022] Step S3: Coat the solder ring in the solder tank, press the edge of the bottom surface of the lens onto the solder ring, and weld it to fix the lens to the integrated tube shell to form a sealed optical window assembly.

[0023] Step S4: Cover the light window assembly onto the substrate assembly, so that the horizontal part at the lower end of the casing is in contact with the welding layer on the substrate, and perform sealing welding.

[0024] To further address the technical problem addressed by this invention, the high-efficiency ultraviolet light source packaging method provided by this invention includes a mold-assisted positioning process in step S3: a mold with positioning posts is provided, the outer diameter of which is adapted to the inner diameter of the lower end of the reflector cup; the positioning posts are inserted into the reflector cup, making the upper end face of the positioning posts flush with the inner end of the solder groove, and pressure is applied between the mold and the lens for welding to prevent deformation of the integral shell.

[0025] To further address the technical problem addressed by this invention, the present invention provides a packaging method for a high-efficiency ultraviolet light source. The high-efficiency ultraviolet light source further includes a light-confining layer filled within a cavity formed by a lens and a reflector cup. Step S4 specifically includes: inverting the light window assembly so that the lens is positioned below; injecting liquid light-confining layer material into the cavity formed by the reflector cup and the lens, and performing vacuum degassing; inverting the substrate assembly onto the light window assembly and pressing it firmly; and sealing the contact position between the horizontal portion and the welding layer.

[0026] To further address the technical problem addressed by this invention, the present invention provides a packaging method for a high-efficiency ultraviolet light source. The high-efficiency ultraviolet light source further includes a light-confining layer that encapsulates an ultraviolet LED chip in an inverted trapezoidal structure. Step S4 specifically includes: using the reflector cup as a mask, performing surface-active treatment on region A defined by the reflector cup on the bottom surface of the lens to improve the surface wettability of region A; dotting a fixed amount of liquid light-confining layer material onto the upper surface of the ultraviolet LED chip to form protrusions using surface tension; aligning and covering the light window assembly onto the substrate assembly, with region A on the bottom surface of the lens contacting and wetting the liquid light-confining layer material, the material diffusing and being confined within region A under the action of surface tension, forming an inverted trapezoidal structure; and sealing and welding the contact position between the horizontal portion and the welding layer.

[0027] Compared with the prior art, the present invention has the following advantages:

[0028] 1. One-piece tubular structure with the casing and reflector cup integrally formed.

[0029] This invention employs an integrated design of the casing and the reflector cup. On the one hand, it overcomes the problems of high processing difficulty and cost of three-dimensional lenses or brackets in traditional all-inorganic packaging, and the reflector cup with extremely high surface flatness can be obtained by stamping or hot pressing, which is convenient for depositing high-reflectivity films. On the other hand, this structure can achieve high airtightness through laser sealing, which reduces mass production costs while ensuring the long-term reliability of ultraviolet LEDs.

[0030] 2. Unique anti-overflow solder bath with dimensional fit design

[0031] A recessed solder groove is provided at the connection between the housing and the reflector cup, with the outer groove wall height limited to being greater than the inner one (h2>h1) and a specific lens / solder ring size relationship. This forms a physical barrier structure, effectively preventing glass solder from overflowing inward and contaminating the reflector cup during lens hot-pressing and sintering. At the same time, this "groove + offset silkscreen" combination allows for minor lens mounting deviations, and significantly improves the hermeticity and bonding strength of the package by increasing the solder contact area and the tortuosity of the sealing path.

[0032] 3. Introduce a refractive index-matched light confinement layer (optical coupling mechanism)

[0033] A light confinement layer is created by filling the space between the chip and the lens with fluorinated oil or fluorinated resin with a refractive index greater than air (e.g., n≈1.4). This design addresses the strong lateral emission characteristics of deep ultraviolet LED chips and the high refractive index of the sapphire substrate. It significantly reduces the refractive index difference between the chip's emitting surface and the ambient medium, effectively suppressing total internal reflection at the interface. This allows light that would otherwise be confined within the chip or lost due to total internal reflection to be extracted, significantly improving the device's light extraction efficiency.

[0034] 4. Inverted trapezoidal / fully filled limiting structure based on surface tension self-assembly

[0035] This paper innovatively proposes a process for achieving the self-assembly of an "inverted trapezoidal" light confinement layer by locally modifying the bottom surface of the lens (hydrophilic / hydrophobic treatment), along with a fully filled process using a "limiting ring". Its inverted trapezoidal structure eliminates the need for physical sidewalls, adapting to reflector cup designs with larger tilt angles and facilitating high-density, small-size light source packaging. Furthermore, during the formation of the inverted trapezoidal structure, the reflector cup is cleverly used as a mask to directionally treat the surface in region A of the bottom surface of the lens, easily forming the inverted trapezoidal structure. The fully filled structure, through the design of the limiting ring on the substrate, effectively solves the problem of liquid optical materials overflowing under gravity, ensuring process stability. Attached Figure Description

[0036] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0037] Figure 1 This is a structural schematic diagram of Embodiment 1 of the present invention;

[0038] Figure 2 This is a schematic diagram of the structure of Embodiment 2 of the present invention;

[0039] Figure 3 This is a schematic cross-sectional view of the first type of integrated tubular shell;

[0040] Figure 4 This is a cross-sectional schematic diagram of the second type of integrated tube shell;

[0041] Figure 5This is a cross-sectional schematic diagram of the third type of integrated tubular shell;

[0042] Figure 6 This is one of the schematic diagrams illustrating the assembly process of the lens and the integrated housing;

[0043] Figure 7 This is the second schematic diagram of the assembly process of the lens and the integrated housing;

[0044] Figure 8 This is a schematic diagram of the packaging process in Embodiment 2;

[0045] Figure 9 This is the second schematic diagram of the packaging process in Embodiment 2;

[0046] Figure 10 This is a schematic diagram of the packaging process in Embodiment 1;

[0047] Figure 11 This is the second schematic diagram of the packaging process in Example 1. Detailed Implementation

[0048] To enable those skilled in the art to better understand the technical solution of the present invention, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0049] like Figures 1-11 As shown, this embodiment provides a high-efficiency ultraviolet light source. This device aims to significantly improve the light extraction efficiency of deep ultraviolet LEDs while ensuring high airtightness and reliability. The ultraviolet light source mainly includes a substrate 1, an ultraviolet LED chip 2, and a light window assembly packaged on the substrate 1.

[0050] The substrate 1, serving as the overall support and heat dissipation component, is preferably made of a high thermal conductivity material such as ceramic or metal to meet the heat dissipation requirements of the deep ultraviolet LED. An inner electrode layer 11 and a solder layer 12 surrounding the inner electrode layer 11 are provided on the upper surface of the substrate 1. The ultraviolet LED chip 2 is fixed to the inner electrode layer 11 by eutectic bonding or solder paste soldering. In this embodiment, the ultraviolet LED chip 2 is preferably a deep ultraviolet LED chip with an emission wavelength less than 280nm, but a short-wavelength ultraviolet chip (wavelength less than 360nm) with a strong aging effect on organic materials can also be used depending on actual needs. To achieve electrical connection, an outer electrode layer 14 for connecting to an external power supply is provided on the lower surface of the substrate 1. This outer electrode layer 14 and the corresponding inner electrode layer 11 are typically electrically connected through conductive vias inside the substrate or side circuit layers.

[0051] The light window assembly is fastened to the substrate 1 to form a sealed cavity. Specifically, the light window assembly includes a lens 3 located directly above the ultraviolet LED chip 2, and an integrated housing 4 for supporting the lens 3. The lens 3 is preferably a convex lens to enhance light emission, but a planar lens may also be used depending on the application.

[0052] Regarding the specific structure of the integrated housing 4, it includes a casing 41 surrounding the ultraviolet LED chip 2, and a reflective cup 42 located inside the casing 41 and also surrounding the ultraviolet LED chip 2. Considering the compatibility with the lens 3 (usually made of high ultraviolet transmittance materials such as quartz, sapphire, or glass) and the substrate 1, the integrated housing 4 is preferably made of a material that is easy to process and has a low coefficient of thermal expansion, such as Kovar alloy, iron-nickel alloy, or Invar alloy.

[0053] The lower end of the casing 41 integrally extends a horizontal portion 411. The bottom surface of the horizontal portion 411 is tightly bonded to the welding layer 12 on the upper surface of the substrate 1 and sealed together by laser ablation. To ensure high hermeticity of the packaging structure, the contact surface between the welding layer 12 and the horizontal portion 411 is processed to have high flatness, thereby ensuring the quality of laser welding. Of course, the welding method between the horizontal portion 411 and the welding layer 12 can also be eutectic welding or thermal resistance welding; no specific limitation is made here.

[0054] like Figure 1 As shown, to improve light extraction efficiency, the upper surface of the reflective cup 42 is constructed as a reflective surface 421 that gradually rises from the inside out. To further reduce light loss, a reflective layer 4211 is provided on the reflective surface 421, which has excellent reflectivity and extremely low absorption for deep ultraviolet light. In specific implementations, it is preferable to form a high-reflectivity layer in the deep ultraviolet band on the reflective surface 421 by sputtering or evaporation processes; the material can be a metal reflective layer, a dielectric reflective layer, or a Bragg reflective layer.

[0055] In terms of geometry, the reflective surface of the reflective cup 42 can be designed as a slope (i.e., annular slope) or an arc (i.e., annular arc).

[0056] When a beveled design is adopted, the angle γ between the beveled surface of the reflective cup 42 and the substrate 1 (the reflective surface is actually an annular bevel, and the angle γ here is the angle between the annular bevel and the horizontal plane where the substrate 1 is located) is preferably controlled within the range of 20°-60°. Furthermore, there are specific technical differences regarding the optimal range of this angle:

[0057] Firstly, for ultraviolet light source embodiments employing a fully filled light confinement layer (i.e., the light confinement layer 6 fills the cavity formed by the reflector cup 42 and the lens 3), the optimal angle range for the included angle γ is 20°-45°. This angle range is of critical technical significance: if the included angle is less than 20°, the package size will be too large, making it difficult to increase power density; if the included angle is greater than 45°, because the fully filled medium changes the optical path environment, an excessively large tilt angle will cause laterally transmitted light to be easily reflected back into the chip 2 after touching the reflector cup wall, or even total internal reflection lock-in, resulting in severe absorption loss and preventing effective light extraction.

[0058] Secondly, for the ultraviolet light source embodiment employing an inverted trapezoidal light confinement layer (i.e., the light confinement layer 6 is only partially filled and is inverted trapezoidal), the optimal angle range for the included angle γ is 30°-60°. The principle behind setting this angle range is that if near-horizontal light is incident on the reflector cup 42, an included angle of 45° is best, as it is most conducive to converting the light into vertically upward emitted light. However, in practical applications, considering the refraction and deflection of deep ultraviolet light at the inverted trapezoidal medium interface, and the potential effects of multiple Fresnel reflections on the light path, a relatively wide and steeper range (30°-60°) needs to be set to cover light with different incident angles to ensure optimal overall light extraction efficiency.

[0059] Furthermore, when using a curved surface design, the reflector cup 42 can be a regular curved surface or a free-form surface. If a regular curved surface is used, such as a toroidal sphere, parabola, or ellipsoid, it is preferable to place the ultraviolet LED chip 2 at the focal point of the regular curved reflector cup 42, using geometric optical properties to organize the scattered light into parallel or converging light. If a free-form surface is used, a specific surface equation is calculated through computer-aided optical simulation, aiming to accurately focus the light rays emitted from the ultraviolet LED chip 2 at various angles to the central region at the bottom of the lens 3, thereby maximizing the use of the optical performance of the lens 3 and improving the central light intensity.

[0060] To achieve a reliable connection between the lens 3 and the housing, this embodiment improves the connection structure. The housing 41 and the reflector cup 42 are integrally formed, which not only ensures the flatness of the reflector cup 42 and solves the problem of difficult flatness control in traditional split reflector cups, but also facilitates direct forming using thin sheet material through stamping or hot pressing to obtain an extremely flat curved surface shape. A recessed solder groove 43 is provided at the connection transition between the housing 41 and the reflector cup 42, and the solder groove 43 is filled with a solder ring 5. The edge of the lower surface of the lens 3 is pressed onto the solder ring 5 and fixed by high-temperature sintering. The solder ring 5 is preferably made of glass solder, and the integral housing 4 and the lens 3 are fused together by a sintering process to form an internal space with high airtightness for accommodating the ultraviolet LED chip 2. Of course, the welding method between the integral housing 4 and the lens 3 can also be brazing, eutectic bonding, or other welding methods.

[0061] like Figures 3 to 5 As shown, the cross-sectional shape of the solder bath 43 can vary depending on the processing technology. For example, Figure 3 The bottom surface of the solder bath 43 shown is a plane; Figure 4 The solder trough 43 shown has a V-shaped cross-section; Figure 5 The solder trough 43 shown has a U-shaped cross-section. Regardless of the shape, its core purpose is to effectively restrict the flow of molten glass solder (solder ring 5).

[0062] In this embodiment, the solder ring 5 is preferably coated by screen printing. The solder ring 5 is slightly offset outwards, which, together with the integrally formed solder groove 43, enables precise positioning. This structure of "offset screen printing" combined with "groove restriction" not only ensures that the solder completely fills the bottom of the solder groove 43, but also compresses the sidewall solder during the pressing of the lens 3, increasing the sintering contact area and forming a tortuous sealing path, thereby significantly improving the bonding strength and airtightness.

[0063] To ensure the above effects, prevent solder from overflowing inwards and contaminating the reflector cup 42, and tolerate slight mounting misalignment of the lens 3, such as... Figure 6 As shown, the dimensional relationship between the solder groove 43 and the solder ring 5 in this embodiment is optimized as follows:

[0064] First, the solder trough 43 has an outer wall and an inner wall to form a physical barrier, preventing solder from overflowing into the reflector cup 42 during lens pressing. Preferably, the height h2 of the outer wall of the solder trough 43 is designed to be greater than the height h1 of its inner wall, and the height difference between h2 and h1 is not less than 50 μm (this height difference is sufficient to provide a blocking effect when the overall height of the integrated housing 4 typically does not exceed 800 micrometers). Furthermore, the solder ring 5 is slightly offset outwards.

[0065] Second, let the inner end radius of the solder groove 43 be r, the outer end radius be R, and the radius of the lens 3 be R0. The three satisfy the relationship: R0 > (r + R) / 2. This relationship ensures that the lens can fully cover the solder area, and the solder groove 43 can effectively limit the position of the lens.

[0066] Third, in the initial state before the lens 3 is pressed, the height h3 of the solder ring 5 should be higher than the height h2 of the outer side wall of the solder groove 43; at the same time, let the inner diameter of the solder ring 5 be r1 and the outer diameter be R1, then the relationship is satisfied: (r + R0) / 2 ≤ r1 < R0, and R1 > R.

[0067] The above dimensional coordination ensures that during the pressing process of the lens 3, the solder ring 5 will neither be completely offset nor overflow into the reflector cup 42. Even if the lens 3 has a slight offset, the melted solder can fill the groove, ensuring the consistency and airtightness of the welding.

[0068] In addition, as Figure 7 shown, in order to ensure the sintering accuracy, a special mold 7 is introduced in the sintering process of the present invention. The mold 7 has a positioning column 71, and the outer diameter of the positioning column 71 is adapted to the inner diameter of the lower end of the reflector cup 42. During sintering, the positioning column 71 is clamped into the reflector cup 42, and the upper end surface of the positioning column 71 is flush with the inner end height of the solder groove 43. According to the sintering process conditions, a certain pressure can be applied between the mold 7 and the lens 3. Due to the good toughness of the integrated package 4 and the supporting effect of the mold 7, it can be ensured that the entire component does not deform during the high-temperature sintering process, ensuring the operability of the process and the yield of the finished product.

[0069] Furthermore, in order to solve the problem of low light extraction efficiency of the ultraviolet LED chip, the ultraviolet light source further includes a light confinement layer 6 disposed between the chip and the lens.

[0070] Regarding the principle and material selection of the light confinement layer:

[0071] In the traditional deep ultraviolet LED inorganic package, the space between the chip and the lens is usually filled with air or nitrogen, and its refractive index is about 1, while the deep ultraviolet LED chip 2 usually uses a sapphire substrate, and its refractive index is about 1.77. This large refractive index difference causes serious total reflection inside the chip, and a large amount of light cannot be emitted. Therefore, the light confinement layer 6 in this embodiment uses an optical coupling medium with a refractive index greater than that of air, and its refractive index is usually around 1.4. By introducing the light confinement layer 6, the refractive index difference between the ultraviolet LED chip 2 and the surrounding medium is greatly reduced, thereby significantly reducing total reflection and improving the light extraction efficiency of the chip.

[0072] In terms of material selection, the light confinement layer 6 can be filled with either liquid materials such as fluorinated oil or curable materials such as fluororesin. To ensure the best light coupling effect, the distance between the top surface of the ultraviolet LED chip 2 and the bottom surface of the lens 3 is preferably controlled within 100μm, and the smaller the distance, the better, within the range allowed by the process.

[0073] Depending on the filling pattern, the present invention provides two preferred implementation structures:

[0074] Implementation Method 1: Inverted Trapezoidal Structure (Partially Filled)

[0075] like Figure 1 , Figure 10 and Figure 11 As shown, the light confinement layer 6 is constructed as an inverted trapezoidal structure that encloses the ultraviolet LED chip 2, meaning that the light confinement layer 6 only partially fills the cavity formed by the reflector cup 42 and the lens 3. The bottom surface of the lens 3 is pressed against the upper end of the light confinement layer 6.

[0076] Considering that the quartz lens 3 has poor natural wettability with fluorinated oil or fluorinated resin, and that direct application of adhesive makes it difficult to control its shape, this embodiment employs a special interface treatment process. Specifically, a surface-active material is pre-applied to the bottom surface of the lens 3, and this surface-active material is distributed within region A defined by the reflector cup 42 as a mask.

[0077] like Figure 10 As shown, the manufacturing process is as follows: Using the reflector cup 42 as a mask, directional surface treatment is performed on region A of the bottom surface of the lens 3. Treatment methods include directional sputtering of a dielectric layer, directional surface roughening, directional plasma cleaning, or directional spraying of a dielectric layer and coupling agent. Through these treatments, the surface wettability of region A is significantly improved.

[0078] Subsequently, as Figure 11 As shown, fluorinated oil or fluororesin is dotted onto the surface of the UV LED chip 2, forming a convex medium using the surface tension of the chip surface. Then, the light window is closed, and the area A on the bottom surface of the lens 3, after being wetted, rapidly absorbs and guides the diffusion of the fluorinated oil or fluororesin. Due to the surface tension generated by the difference in wettability at the edge of area A, the liquid stops at the boundary of area A, thus forming a... Figure 1 The structure shown resembles an inverted trapezoid, wider at the top and narrower at the bottom. This surface tension self-assembly process achieves a simple and effective shaping of the light confinement layer 6, making it highly suitable for mass production.

[0079] In this structure, curable organic deep UV-resistant materials such as fluoropolymers are preferred. Compared to fluoropolymers, fluoropolymers can be fixed after curing, avoiding the deformation or displacement problems that occur with fluoropolymers under later thermal shocks or prolonged high-temperature operation.

[0080] From an optical design perspective, if the light confinement layer 6 has an inverted trapezoidal structure, the angle β between its side surface and the upper surface of the substrate 1 is preferably less than 75°. This is because the total internal reflection angle corresponding to fluorinated oil or fluorinated resin (refractive index approximately 1.4) is approximately 45°, while the proportion of light emitted by a typical ultraviolet LED chip within a vertical angle of 60° exceeds 90%. To ensure that this portion of light can undergo total internal reflection and be emitted upwards when it exits the sidewall of the light confinement layer 6, the side tilt angle β should satisfy: β < 90° - (60° - 45°) = 75°.

[0081] Implementation Method 2: Fully Filled Structure

[0082] like Figure 2 , Figure 8 and Figure 9 As shown, the light-confining layer 6 can also be completely filled within the cavity formed by the reflector cup 42 and the lens 3.

[0083] The manufacturing process of this structure mainly employs the "inverted potting method". For example... Figure 8 As shown, the light window assembly containing lens 3 and integrated housing 4 is first inverted, and adhesive is injected into the accommodating cavity by injection or dispensing. Then, vacuum degassing is performed to ensure that there are no air bubbles in the adhesive and that the accommodating cavity is completely filled. Finally, the substrate 1 with the die-bonded ultraviolet LED chip 2 is inverted and covered, and after pressing, the contact position between the welding layer 12 and the horizontal part 411 is laser-sealed.

[0084] If the light confinement layer 6 is made of a fluid fluorinated oil material, in order to prevent the fluorinated oil from overflowing from the gap between the reflector cup 42 and the substrate 1 under gravity, such as... Figure 2 and Figure 9 As shown, a protruding limiting ring 13 is also provided directly below the inner end of the reflector cup 42. The limiting ring 13 can be directly disposed on the upper surface of the substrate 1, or it can be integrally disposed on the upper surface of the welding layer 12, or the inner end of the welding layer 12 itself can serve as the limiting ring 13 (this method requires the welding layer 12 to have sufficient height). The limiting ring 13 is located directly below the inner end of the reflector cup 42, and its upper end abuts against the lower surface of the reflector cup 42 (preferably tightly pressed together to form a sealed connection and prevent the light-containing layer 6 from overflowing).

[0085] The height of the limiting ring 13 is preferably not less than 50 μm and not more than 200 μm. This height design adapts to the height position of the reflector cup 42 and also takes into account the slight deformation that may occur in the reflector cup 42 during processing and sintering. Utilizing the deformation characteristics of the limiting ring 13 (usually made of electroplated copper, which is relatively soft), excellent sealing performance can be achieved without generating excessive stress on the light window assembly, thus preventing fluorinated oil leakage.

[0086] Comparison of the two implementation methods and their application scenarios:

[0087] The fully filled structure is relatively simple to process and easy to implement, but in order to reflect more light toward the lens, the tilt angle of the reflector cup 42 is required to be small, which will result in a larger overall device area, making it unsuitable for high-density light source applications. On the other hand, although the coating process of the inverted trapezoidal structure is more complex, it allows the reflector cup 42 to have a larger tilt angle, which can make the device smaller and improve the light output density, making it suitable for scenarios with high integration requirements.

[0088] This invention also discloses a packaging method for a high-efficiency ultraviolet light source, comprising the following steps:

[0089] Step S1: Provide a substrate 1, and weld and fix the ultraviolet LED chip 2 on the inner electrode layer 11 on the upper surface of the substrate 1 to form a substrate assembly;

[0090] Step S2: Provide lens 3 and integrally formed tube shell 4, wherein the integral tube shell 4 includes a casing 41, a reflector cup 42 and a recessed solder groove 43 located at the connection between the two.

[0091] Step S3: Coat the solder ring 5 in the solder tank 43, press the edge of the bottom surface of the lens 3 onto the solder ring 5, and weld it to fix the lens 3 to the integrated tube shell 4 to form a sealed optical window assembly.

[0092] Step S4: Cover the light window assembly onto the substrate assembly, so that the horizontal portion 411 at the lower end of the housing 41 is attached to the welding layer 12 on the substrate 1, and perform sealing welding (e.g., sintering).

[0093] This method involves fabricating the substrate assembly (including the chip) and the light window assembly (lens + housing) separately. This split process avoids the high-temperature sintering process (typically at high temperatures) of the lens and housing directly affecting the sensitive deep ultraviolet LED chip, preventing damage due to thermal stress. Simultaneously, it allows for independent testing of the airtightness and structural integrity of the light window assembly before final sealing, screening out defective products and preventing the scrapping of expensive deep ultraviolet LED chips due to packaging defects, significantly reducing production costs.

[0094] Furthermore, in step S3, the welding process uses a mold 7 for assisted positioning: a mold 7 with a positioning post 71 is provided, the outer diameter of which is adapted to the inner diameter of the lower end of the reflector cup 42; the positioning post 71 is inserted into the reflector cup 42, so that the upper end face of the positioning post 71 is flush with the inner end of the solder groove 43, and pressure is applied between the mold 7 and the lens 3 for welding to prevent deformation of the integral tube shell 4.

[0095] Furthermore, in step S3, as Figure 6As shown, the solder ring 5 is coated using a screen printing method, and its size and position preferably satisfy the relationship described above. This method ensures a large sealing contact area and prevents the solder from contaminating the reflector cup 42.

[0096] Furthermore, the high-efficiency ultraviolet light source also includes a light-confining layer 6 filled within the cavity formed by the lens 3 and the reflector cup 42. Step S4 specifically includes: inverting the light window assembly so that the lens 3 is positioned below; injecting liquid light-confining layer material into the cavity formed by the reflector cup 42 and the lens 3, and performing vacuum degassing; inverting the substrate assembly onto the light window assembly and pressing it firmly, and sealing the contact position between the horizontal portion 411 and the welding layer 12 (e.g., laser sealing). This method employs a process of "inverted light window injection + vacuum degassing + inverted substrate," cleverly utilizing gravity and a vacuum environment to solve the problems of bubbles and overflow that are easily generated in traditional potting, ensuring the purity of the light path.

[0097] Furthermore, the high-efficiency ultraviolet light source also includes a light confinement layer 6 encasing the ultraviolet LED chip 2 in an inverted trapezoidal structure. Step S4 specifically includes: using the reflector cup 42 as a mask, performing surface activation treatment on the area A defined by the reflector cup 42 on the bottom surface of the lens 3 to improve the surface wettability of area A; dotting a fixed amount of liquid light confinement layer material on the upper surface of the ultraviolet LED chip 2 to form protrusions using surface tension; aligning and covering the light window assembly onto the substrate assembly, with area A on the bottom surface of the lens 3 contacting and wetting the liquid light confinement layer material, the material diffusing and being confined within area A under the action of surface tension, forming an inverted trapezoidal structure; sealing the contact position between the horizontal part 411 and the welding layer 12 (e.g., laser sealing). Finally, the light confinement layer material can be cured; if the viscosity of the light confinement layer is sufficient, the curing step can be omitted. This embodiment innovatively utilizes the reflector cup as a mask for surface activation treatment, and utilizes the principle of "surface tension self-assembly" to allow the liquid medium to automatically form an inverted trapezoidal structure at the moment of pressing. This method can precisely control the shape of the fluid without the need for additional micro-molds, which greatly simplifies the manufacturing difficulty of complex optical structures and is suitable for mass production.

[0098] Obviously, the above embodiments of the present invention are merely examples for clearly illustrating the present invention, and are not intended to limit the implementation of the present invention. Those skilled in the art can make other variations or modifications based on the above description. It is neither necessary nor possible to exhaustively describe all embodiments here. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the claims of the present invention.

Claims

1. A high-efficiency ultraviolet light source, characterized in that: It includes a substrate (1), an ultraviolet LED chip (2), and an optical window; on the upper surface of the substrate (1), there are provided an inner electrode layer (11) and a welding layer (12) arranged around the inner electrode layer (11). The ultraviolet LED chip (2) is welded on the inner electrode layer (11); the optical window includes a lens (3) directly above the ultraviolet LED chip (2) and an integral shell (4) for supporting the lens (3); the integral shell (4) includes an enclosing shell (41) arranged around the ultraviolet LED chip (2) and a reflecting cup (42) located inside the enclosing shell (41) and arranged around the ultraviolet LED chip (2); at the lower end of the enclosing shell (41), there is provided a horizontally extending portion (411), and the bottom surface of the horizontally extending portion (411) is hermetically welded to the welding layer (12) of the substrate (1); the upper surface of the reflecting cup (42) is configured as a reflecting surface (421) that gradually rises from the inside to the outside, and a reflecting layer (4211) is provided on the reflecting surface (421); the enclosing shell (41) and the reflecting cup (42) are integrally formed, and at the connection between the two, there is a downward concave solder groove (43), and a solder ring (5) is provided in the solder groove (43). The edge of the lower surface of the lens (3) is pressed on the solder ring (5) and welded and fixed.

2. The high-efficiency ultraviolet light source according to claim 1, characterized in that: The height h2 of the outer side wall of the solder groove (43) is greater than the height h1 of its inner side wall.

3. The high-efficiency ultraviolet light source according to claim 2, characterized in that: The inner end radius of the solder groove (43) is r, the outer end radius of the solder groove (43) is R, and the radius of the lens (3) is R0. The three satisfy the following relationship: R0 > (r + R) / 2.

4. A high-efficiency ultraviolet light source according to claim 3, characterized in that: Before the lens (3) is pressed, the height h3 of the solder ring (5) is higher than the height h2 of the outer side wall of the solder groove (43); and before the lens (3) is pressed, the inner diameter of the solder ring (5) is r1, and the outer diameter of the solder ring (5) is R1, satisfying the following relationship: (r + R0) / 2 ≤ r1 < R0, and R1 > R.

5. A high-efficiency ultraviolet light source according to claim 1, characterized in that: It further includes a light limiting layer (6). The light limiting layer (6) uses an optical coupling medium with a refractive index greater than that of air; the light limiting layer (6) is configured as an inverted trapezoidal structure that wraps the ultraviolet LED chip (2), or the light limiting layer (6) is filled in the cavity formed by the reflecting cup (42) and the lens (3).

6. A high-efficiency ultraviolet light source according to claim 5, characterized in that: If the light limiting layer (6) is an inverted trapezoidal structure, the bottom surface of the lens (3) is pressed on the upper end of the light limiting layer (6); a surface active material is sprayed on the bottom surface of the lens (3), and the surface active material is distributed in the area A defined by the reflecting cup (42) as a mask; the inverted trapezoidal light limiting layer (6) is formed by the convex light limiting layer (6) medium dot-coated on the ultraviolet LED chip (2) under the pressing action of the bottom surface of the lens (3).

7. A high-efficiency ultraviolet light source according to claim 6, characterized in that: If the light limiting layer (6) is an inverted trapezoidal structure, the included angle β between the side surface of the light limiting layer (6) and the upper surface of the substrate (1) is less than 75°.

8. A high-efficiency ultraviolet light source according to claim 1, characterized in that: The upper surface of the substrate (1) or the welding layer (12) is also provided with an upwardly protruding limiting ring (13). The limiting ring (13) is located below the inner end of the reflector cup (42), and the upper end of the limiting ring (13) abuts against the lower surface of the reflector cup (42).

9. A high-efficiency ultraviolet light source according to claim 1, characterized in that: The reflective surface (421) of the reflective cup (42) is inclined or curved; if the reflective surface (421) of the reflective cup (42) is inclined, the angle γ between the inclined surface of the reflective surface (421) of the reflective cup (42) and the substrate (1) is in the range of 20°-60°.

10. A method for packaging a high-efficiency ultraviolet light source according to any one of claims 1-9, characterized in that, Includes the following steps: Step S1: Provide a substrate (1), and weld and fix the ultraviolet LED chip (2) on the inner electrode layer (11) on the upper surface of the substrate (1) to form a substrate assembly; Step S2: Provide a lens (3) and an integrally formed tube shell (4), the integral tube shell (4) including a casing (41), a reflector cup (42) and a recessed solder groove (43) located at the connection between the two; Step S3: Coat the solder ring (5) in the solder tank (43), press the edge of the bottom surface of the lens (3) onto the solder ring (5) and weld it to fix the lens (3) to the integrated tube shell (4) to form a sealed optical window assembly. Step S4: Cover the light window assembly onto the substrate assembly, so that the horizontal part (411) at the lower end of the casing (41) is attached to the welding layer (12) on the substrate (1) and perform sealing welding.

11. The packaging method for a high-efficiency ultraviolet light source according to claim 10, characterized in that, In step S3, the welding process uses a mold (7) for assisted positioning: a mold (7) with a positioning post (71) is provided, the outer diameter of which is adapted to the inner diameter of the lower end of the reflector cup (42); the positioning post (71) is inserted into the reflector cup (42) so that the upper end face of the positioning post (71) is flush with the inner end of the solder groove (43), and pressure is applied between the mold (7) and the lens (3) for welding to prevent deformation of the integral tube shell (4).

12. The packaging method for a high-efficiency ultraviolet light source according to claim 10, characterized in that, The high-efficiency ultraviolet light source also includes a light-confining layer (6) filled in the cavity formed by the lens (3) and the reflector cup (42); step S4 specifically includes: inverting the light window assembly so that the lens (3) is located below; injecting liquid light-confining layer material into the cavity formed by the reflector cup (42) and the lens (3) and performing vacuum debubbling; inverting the substrate assembly onto the light window assembly and pressing it tightly, and sealing the contact position between the horizontal part (411) and the welding layer (12).

13. The packaging method for a high-efficiency ultraviolet light source according to claim 10, characterized in that, The high-efficiency ultraviolet light source also includes a light confinement layer (6) that encapsulates the ultraviolet LED chip (2) in an inverted trapezoidal structure; step S4 specifically includes: using the reflector cup (42) as a mask, performing surface activity treatment on the area A defined by the reflector cup (42) on the bottom surface of the lens (3) to improve the surface wettability of area A; applying a fixed amount of liquid light confinement layer material to the upper surface of the ultraviolet LED chip (2) to form a protrusion using surface tension; aligning the light window assembly and covering it on the substrate assembly, so that area A on the bottom surface of the lens (3) contacts and wets the liquid light confinement layer material, and the material diffuses and is confined within area A under the action of surface tension to form an inverted trapezoidal structure; and sealing the contact position between the horizontal part (411) and the welding layer (12) by welding.

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