Self-sealing inorganic sealing LED light source and inorganic sealing method

Abstract

The application discloses a kind of self-sealing inorganic sealing welding LED light source and inorganic sealing welding method, LED light source includes substrate, LED chip and light window, substrate top surface is equipped with electrode layer, welding layer, and LED chip is welded on electrode layer;Light window includes tube shell, lens, and the lower end of tube shell is welded on welding layer;It is equipped with ring cup-shaped light cup around LED chip in tube shell, and the outer side of the bottom surface of light cup is equipped with the positioning gap of opening outward along circumference, and the corresponding position of welding layer is equipped with the positioning dam for cooperating with positioning gap to position light cup, and positioning dam is equipped with the sealing glue for bonding fixed light cup, and part of sealing glue overflow is connected with welding layer and is sealed;Positioning dam includes inner dam, middle dam and outer dam sequentially arranged from inside to outside, and satisfy middle dam height h2>Inner dam height h1≥Outer dam height h3.The application has the advantages of good air tightness and high light extraction efficiency.

Description

Technical Field

[0001] This invention relates to the field of LED light source technology, and in particular to a self-sealing inorganic sealing LED light source and an inorganic sealing method. Background Technology

[0002] Deep ultraviolet LEDs, with their significant advantages such as being mercury-free and environmentally friendly, having a fast response speed, and being small in size, have become the core solution for replacing traditional harmful mercury lamps and achieving sterilization and disinfection functions.

[0003] However, deep ultraviolet light possesses extremely high photon energy, which can severely damage the silicone materials widely used in traditional visible light LED packaging, leading to yellowing, brittleness, and consequently, severe light decay and hermeticity failure. Although early attempts were made to use organic packaging materials or semi-inorganic packaging (using inorganic lenses but still bonded with organic adhesives) in low-end, low-power deep ultraviolet LED packaging, these methods have become insufficient to meet the demands for long lifespan and high stability as market requirements for device reliability continue to increase. Therefore, developing a fully inorganic packaging technology with excellent UV aging resistance is an inevitable trend for achieving high-reliability packaging of deep ultraviolet LEDs.

[0004] Currently, a mainstream all-inorganic packaging system has gradually developed in the industry. This system uses a quartz lens as the optical window, combined with a ceramic substrate, and employs gold-tin eutectic bonding for chip bonding. Laser sealing technology is then used to connect the lens housing to the substrate. While this technology addresses the aging problem of organic materials to some extent, existing technologies still face the following key bottlenecks in practical applications:

[0005] 1) Airtightness and reliability issues: Existing laser sealing processes are prone to thermal stress at the sealing interface, leading to microcracks in the weld; at the same time, voids are easily formed in the solder layer. These defects allow external moisture to penetrate into the device, seriously affecting its service life and reliability.

[0006] 2) Low light extraction efficiency: Deep ultraviolet LED chips (especially high-aluminum chips) have a unique light field distribution, with a large proportion of lateral light emission from their TM mode (transverse magnetic mode). This portion of light is easily blocked and lost by the dams in the packaging structure. In addition, due to the abrupt change in refractive index between the chip, air, and packaging materials, strong Fresnel reflection is easily induced. Combined with the absorption and reflection losses of light by the metal window itself, this results in a low overall light extraction efficiency of the device, which greatly restricts the improvement of device power.

[0007] 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

[0008] The purpose of this invention is to overcome the shortcomings of the prior art and provide a self-sealing inorganic LED light source with good airtightness and high light extraction efficiency, as well as an inorganic sealing method.

[0009] This invention can be achieved through the following technical solutions:

[0010] To solve the above technical problems, the present invention provides a self-sealing inorganic sealing LED light source, including a substrate, an LED chip and a light window. The top surface of the substrate is provided with an electrode layer and a welding layer disposed around the electrode layer. The LED chip is welded to the electrode layer. The light window includes a housing disposed around the LED chip and a lens welded to the top opening of the housing. The lower end of the housing is welded to the welding layer.

[0011] The tube shell is provided with a ring-shaped reflector cup surrounding the LED chip. The outer side of the bottom surface of the reflector cup is provided with a positioning notch with an outward opening along the circumferential direction. The corresponding position of the welding layer is provided with a positioning dam for cooperating with the positioning notch to position the reflector cup. The positioning dam is provided with sealant for bonding and fixing the reflector cup. Some of the sealant overflows to the connection between the tube shell and the welding layer and seals it.

[0012] The positioning dam includes an inner dam, a middle dam, and an outer dam arranged sequentially from the inside to the outside, and satisfies the following conditions: the height of the middle dam h2 > the height of the inner dam h1 ≥ the height of the outer dam h3.

[0013] To further address the technical problems addressed by this invention, this invention provides a self-sealing inorganic LED light source in which the inner surface of the reflector cup is a first reflective surface that gradually slopes outward from bottom to top, and a reflective layer is provided on the first reflective surface. The first reflective surface is an inclined surface or an arc-shaped surface. The top surface of the reflector cup is a second reflective surface, and a reflective layer is also provided on the second reflective surface. The second reflective surface and the bottom surface of the lens are spaced apart.

[0014] To further address the technical problem to be solved by this invention, this invention provides a self-sealing inorganic sealing LED light source in which the positioning notch has an inner top surface, and the inner top surface is a sloping surface that gradually slopes outward from bottom to top.

[0015] To further address the technical problem addressed by this invention, the present invention provides a self-sealing inorganic sealing LED light source in which the inclination angle α of the inner top surface relative to the horizontal plane is not less than 15°.

[0016] To further address the technical problems addressed by this invention, the present invention provides a self-sealing inorganic LED light source in which the cross-section of the positioning notch is a sideways trapezoidal shape, with an outer ring height of h4, an inner ring height of h5, and a radial width of l; the cross-section of the reflector cup has a height of H and a width of L, satisfying the following conditions: h4≤1 / 2H, h5≤1 / 3H, l≤1 / 2L.

[0017] To further address the technical problems to be solved by this invention, this invention provides a self-sealing inorganic sealing LED light source in which the height h2 of the central dam is greater than the inner ring height h5 of the positioning notch.

[0018] To further address the technical problems addressed by this invention, the present invention provides a self-sealing inorganic sealing LED light source in which the outer wall of the reflector cup and the inner wall of the tube shell are spaced by a distance d1, the outer dam and the inner wall of the tube shell are spaced by a distance d2, and the inner dam and the inner ring of the positioning notch are spaced by a distance d3, wherein the following conditions are met: 50μm≤d1≤300μm, 50μm≤d2≤200μm, and d3≤100μm.

[0019] To further address the technical problems addressed by this invention, the present invention provides a self-sealing inorganic LED light source in which the surface of the LED chip is covered with an optical coupling medium, the optical coupling medium having an inverted trapezoidal structure that encloses the LED chip, or the optical coupling medium filling the cavity formed by the reflector cup.

[0020] This invention can also be achieved through the following technical solutions:

[0021] An inorganic sealing method for LED light sources, used for encapsulating the aforementioned self-sealing inorganic LED light source, includes the following steps:

[0022] Step S1: Prepare materials, namely, prepare the designed substrate, light window, reflector, LED chip, and sealant.

[0023] Step S2, chip welding, that is, using the die bonding method to weld the LED chip onto the electrode layer of the substrate;

[0024] Step S3, dispensing, that is, applying sealant to the inner and outer dams using a dispensing machine, and forming the sealant into a raised shape to cover the middle dam;

[0025] Step S4: Cover the reflector cup. After aligning the reflector cup in the correct position, place it on the welding layer. Use the inner dam to position the reflector cup in conjunction with the positioning notch at the bottom of the reflector cup. During the process of pressing down the reflector cup, the sealant will come into contact with the inner top surface of the positioning notch. The inner top surface will press the excess sealant into the gap inside the positioning notch.

[0026] Step S5, shaping treatment, that is, shaping the sealant to initially shape it;

[0027] Step S6, sealing and welding, that is, positioning and pressing the light window onto the substrate, so that the bottom of the tube shell contacts the welding layer on the upper surface of the substrate, and then sealing and welding to fix the light window.

[0028] Step S7, softening treatment, that is, treating the sealant to soften it and reduce its viscosity, controlling the treatment conditions so that the sealant outside the middle dam crosses the outer dam, flows to the contact position between the pipe shell and the weld layer and fills the gap;

[0029] Step S8, sealant curing: After the sealant has flowed and filled evenly, the processing conditions are changed to allow the sealant to fully cure, thereby achieving the bonding and fixing of the reflector cup and the sealing of the connection between the tube shell and the welded layer.

[0030] To further address the technical problem to be solved by this invention, the present invention provides an inorganic sealing method for LED light sources, which further includes the following steps between step S5 and step S6:

[0031] Step S5.5: Apply UV-resistant optical coupling medium to the surface of the LED chip to form an inverted trapezoidal structure that encapsulates the LED chip, or fill the cavity enclosed by the reflector cup with optical coupling medium.

[0032] Compared with the prior art, the present invention has the following advantages:

[0033] 1. Design of a "self-sealing" flow channel based on the height difference of the triple dam.

[0034] This invention innovatively designs a triple-positioning dam structure consisting of an inner dam, a middle dam, and an outer dam, and strictly limits the height difference relationship of "the middle dam is the highest, and the outer dam is the lowest" (h2>h1≥h3). It utilizes the height difference of the dams in conjunction with the rheological properties of the sealant at different temperatures. During secondary heating, the middle dam effectively prevents the sealant from flowing inward, ensuring a stable bond to the reflector cup; simultaneously, it guides the external sealant to break through the lower outer dam and overflow directionally to the laser weld seam between the tube shell and the substrate, automatically filling welding microcracks and pores, significantly solving the technical problem of poor airtightness in existing laser sealing processes.

[0035] 2. The structural fit between the "positioning notch" and the "inner top slope" of the reflector.

[0036] This invention features a positioning notch with an inclined inner top surface at the bottom of the reflector cup. This notch not only works with the retaining wall to achieve precise positioning but also acts as a "compression chamber" and "flow guide" for the sealant. When the reflector cup is pressed down, the inclined inner top surface can compact the high-viscosity adhesive into the gap inside the notch, increasing the bonding area. At the same time, this structure cleverly utilizes physical space to limit the initial position of the adhesive without adding an extra adhesive injection process, preventing uncontrollable overflow during the dispensing stage and ensuring the consistency and reliability of the subsequent "self-sealing" process.

[0037] 3. Total internal reflection deep ultraviolet light extraction optical path design.

[0038] This invention adds an independent annular reflector cup with a highly reflective coating inside a metal casing. The inner surface of the reflector cup is designed as a slope or arc, and the top surface of the reflector cup is spaced apart from the bottom surface of the lens. This structure effectively collects the TM mode light emitted laterally from the deep ultraviolet LED chip and reflects it to the lens, greatly reducing light loss due to absorption by the dam or metal casing. Simultaneously, the reflector cup acts as a physical barrier, preventing deep ultraviolet light from directly irradiating the organic sealant at the bottom, fundamentally solving the problem of easy aging and failure of organic materials in a deep ultraviolet environment, and achieving a long-life encapsulation of "organic bonding and inorganic light emission".

[0039] 4. Optical coupling medium filling and micro-gap thermal expansion compensation mechanism.

[0040] This invention employs a design that encapsulates the chip or fills the reflector cavity with a UV-resistant optical coupling medium, utilizing the micron-level assembly gap (50μm-300μm) between the reflector and the housing / lens as a buffer. The optical coupling medium effectively reduces the abrupt change in refractive index at the chip-air interface, minimizing Fresnel reflection loss and further improving light extraction efficiency. Simultaneously, the reserved micro-gap cleverly solves the problem of thermal expansion of the liquid medium in a fully filled structure, avoiding bubbles or leakage caused by excessive internal pressure and ensuring structural stability under high and low temperature shocks. Attached Figure Description

[0041] The specific embodiments of the present invention will be further described in detail below with reference to the accompanying drawings, wherein:

[0042] Figure 1 This is a cross-sectional schematic diagram of the present invention;

[0043] Figure 2 This is a top view of the substrate;

[0044] Figure 3 This is a structural diagram of the positioning gap and the positioning dam;

[0045] Figure 4 This is a schematic diagram of step S3;

[0046] Figure 5 This is a schematic diagram of step S4;

[0047] Figure 6 This is a cross-sectional schematic diagram of one of the finished products of the present invention;

[0048] Figure 7 This is a cross-sectional schematic diagram of another finished product of the present invention. Detailed Implementation

[0049] 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.

[0050] Example 1: Structure of a self-sealing inorganic LED light source

[0051] like Figures 1 to 7 The self-sealing inorganic LED light source shown includes a substrate 1, an LED chip 2, and a light window 3.

[0052] Specifically, the top surface of the substrate 1 is provided with an electrode layer 11 and a solder layer 12 surrounding the electrode layer 11. The electrode layer 11 includes a positive electrode region and a negative electrode region disposed opposite to each other. The bottom surface of the substrate 1 is provided with a corresponding external electrode 13, which is electrically connected to the corresponding positive and negative electrode layers 11 through vias or side lines inside the substrate, for connecting the LED light source to an external circuit. To improve heat dissipation performance, a thermally conductive solder pad 14 is preferably provided at the center of the bottom surface of the substrate 1.

[0053] The LED chip 2 is soldered onto the electrode layer 11. This LED chip 2 is typically a deep ultraviolet LED chip (wavelength ≤ 280nm) with an emission wavelength in the ultraviolet band, but a mid-ultraviolet LED chip with a wavelength less than 365nm can also be used depending on requirements. The LED chip 2 preferably adopts a flip-chip structure and is fixed by AuSn high-temperature eutectic soldering, nano-solder paste, or SnAgCu eutectic solder to ensure good electrical and thermal conductivity.

[0054] The light window 3 is fastened above the substrate 1 and includes a housing 31 surrounding the LED chip 2 and a lens 32 welded to the top opening of the housing 31. The housing 31 and lens 32 are hermetically sealed using an inorganic solder ring 33 (such as low-temperature glass solder, low-temperature brazing, or metal solder). The housing 31 is preferably made of a metal suitable for sealing, and its shape includes a vertical cylinder 311 and a horizontal portion 312 located around the periphery of the vertical cylinder and extending radially outward. The bottom surface of the horizontal portion 312 is attached to the welding layer 12 of the substrate 1 and fixed by a sealing process. The sealing process here preferably uses a laser sealing process where high-energy laser high-frequency ablation melts the contact surface. Alternatively, AuSn eutectic solder, CuSn low-temperature brazing, or nano-AgCuTi low-temperature brazing solder can be placed between the horizontal portion 312 and the substrate 1, and the sealing process can be completed using the corresponding welding technique.

[0055] Lens 32 can be made of UV-resistant materials such as quartz, sapphire, or CaF2, and its shape can be a plane lens (e.g., Figure 6 (as shown) or a convex lens (such as) Figure 7 (As shown).

[0056] In the core design of this embodiment, to address the issues of light efficiency and sealing, an annular reflector 4 surrounding the LED chip 2 is provided inside the housing 31. The reflector 4 can be made of metal (such as aluminum, iron, copper), glass (such as quartz, sapphire, silicate glass, etc.), or deep ultraviolet-resistant organic materials (such as polyetheretherketone, polyimide, etc.).

[0057] The inner surface of the reflector cup 4 is designed as a first reflective surface 41 that gradually slopes outward from bottom to top. This first reflective surface 41 can be a sloped surface or an arc-shaped surface. The top surface of the reflector cup 4 is designed as a second reflective surface 42. Both the first reflective surface 41 and the second reflective surface 42 are coated with a high reflective layer with a deep ultraviolet reflectivity exceeding 90%, such as a metallic dielectric composite reflective layer composed of Al and MgF2, SiO2, CaF2, etc., or a multi-period Bragg reflector. The second reflective surface 42 is spaced apart from the bottom surface of the lens 32 to avoid stress transmission.

[0058] The bottom surface of the reflector cup 4 is directly bonded to the welding layer 12 with sealant 6. In order to achieve precise positioning and control the flow direction of sealant 6, a positioning notch 43 with an outward opening is provided on the outer side of the bottom surface of the reflector cup 4 along the circumferential direction; correspondingly, a positioning dam 5 that cooperates with the positioning notch 43 is provided on the welding layer 12 of the substrate 1.

[0059] The positioning dams 5 are arranged sequentially from the inside out as an inner dam 51, a middle dam 52, and an outer dam 53, preferably concentrically distributed and integrally integrated with the welding layer 12. The structural parameters of these three dams satisfy the following relationship: the height h2 of the middle dam 52 is greater than the height h1 of the inner dam 51, and the height h1 of the inner dam 51 is greater than or equal to the height h3 of the outer dam 53. The height h3 of the outer dam 53 is not less than 50 μm. This height difference design is to accommodate the flow characteristics of the sealant 6 at different process stages.

[0060] Specifically, the sealant 6 is filled at the positioning dam 5. Due to the special fit between the positioning dam 5 and the positioning notch 43, in the final product, the sealant 6 not only firmly bonds the reflector cup 4 to the substrate 1, but also some of the sealant 6 overflows into the connection gap between the tube shell 31 (horizontal part 312) and the welding layer 12, forming a secondary sealing structure.

[0061] To ensure the machinability and fitting accuracy of the reflector cup 4, the cross-section of the positioning notch 43 is a sideways trapezoidal shape, and its parameters are designed to meet the following requirements: outer ring height h4≤1 / 2H (H is the height of the reflector cup cross-section), inner ring height h5≤1 / 3H, and radial width l≤1 / 2L (L is the width of the reflector cup cross-section).

[0062] Furthermore, to effectively control the initial bonding area of ​​the reflector cup 4 and to effectively control the flow of the sealant 6 (preventing the sealant from overflowing from the outer dam during the process of covering the reflector cup 4), ensuring that the sealant 6 outside the inner dam can effectively overflow, and that the sealant 6 inside the inner dam can effectively fill the cavity of the positioning notch 43, and ensuring effective bonding during the final curing process, the positioning notch 43 has an inner top surface 431, which is a sloping surface that gradually slopes outward from bottom to top. Furthermore, the angle α of the inner top surface 431 relative to the horizontal plane is not less than 15°. This sloping design increases the bonding area and guides the sealant to flow inward during installation and pressing.

[0063] The sealant 6 can be made of organic adhesives with viscosity controlled by temperature or ultrasound, such as stage B epoxy resin, silicone-modified phenolic resin, or polyurethane structural adhesive.

[0064] In this embodiment, the combination of the rheological properties of sealant 6 and the curing process is key to achieving self-sealing. To ensure that sealant 6 has good stackability during the dispensing stage, sufficient holding power during the intermediate stage, and excellent penetration and sealing properties during the final stage, this invention strictly limits the viscosity of sealant 6 at different temperature stages:

[0065] First, during the room temperature dispensing stage, the sealant 6 needs to possess certain thixotropic and shape-retaining properties. The viscosity of the sealant 6 at room temperature is set to be no less than 2000 mPa·s. This setting serves two purposes: firstly, it ensures that the sealant 6, when applied between the inner dam 51 and the outer dam 53, can stably accumulate and remain non-flowing, thus effectively confining it within the inner and outer dams; secondly, the higher initial viscosity allows the sealant 6 to form a convex structure covering the middle dam 52 (i.e., the sealant level is higher than the middle dam), providing a material basis for the subsequent contact and wetting of the inner top surface 431 of the positioning notch 43 during the pressing of the reflector cup 4.

[0066] Secondly, during the initial setting stage (i.e., step S5, heating and setting), the sealant 6 undergoes a heating process, during which its internal molecular chains cross-link or solvent evaporates, resulting in a significant increase in viscosity. At this point, the viscosity of the sealant 6 is required to be no less than 5000 mPa·s. This high viscosity state plays two key roles: firstly, it provides sufficient initial tack to firmly position the reflector cup 4 on the welding layer 12, preventing the reflector cup 4 from shifting; secondly, in the subsequent laser sealing process of the light window 3 (step S6), the high-frequency vibration and local high temperature of the equipment can easily cause splashing or displacement of the low-viscosity fluid, while the sealant 6, in its high-viscosity "semi-cured" state, can resist these disturbances, ensuring that the adhesive will not overflow the outer dam 53 outside of the predetermined time, thereby guaranteeing the cleanliness and yield of the laser sealing process.

[0067] Finally, in the secondary heating and flow stage (i.e., step S7), the system temperature is raised to a specific range, and the thermoplastic or delayed curing properties of the sealant 6 are used to temporarily soften it. At this time, the viscosity of the sealant 6 is significantly reduced, requiring it to be no greater than 4000 mPa·s. In this low viscosity state, the sealant 6 exhibits excellent flowability. Combined with the aforementioned dam height difference design (h2>h1≥h3), since the middle dam 52 is relatively high and its inner space is closed, the low-viscosity adhesive cannot cross the middle dam 52. It can only continue to fill the tiny gaps inside the middle dam under the action of surface tension, further compacting the adhesion of the reflector cup 4. At the same time, the adhesive located outside the middle dam 52, because the outer dam 53 is relatively low, can smoothly break through the restriction of the outer dam 53 after thinning, overflow outwards and migrate directionally to the contact area between the shell 31 and the weld layer 12, filling the microcracks and gaps in the laser weld.

[0068] To accommodate the rheological behavior of the sealant 6 and ensure the controllability of its flow path, this embodiment features a precisely designed fit clearance between the reflector 4, the dam structure, and the casing 31:

[0069] Specifically, a gap d1 is defined between the outer wall of the reflector 4 and the inner wall of the casing 31, a gap d2 is defined between the outer dam 53 and the inner wall of the casing 31, and a gap d3 is defined between the inner dam 51 and the inner ring of the positioning notch 43. These gaps satisfy the following numerical range:

[0070] 50μm≤d1≤300μm: The interval d1 is mainly for the convenience of installing the reflector cup 4 and the tube shell 31.

[0071] 50μm≤d2≤200μm: The interval d2 determines the volume and velocity of the overflow adhesive reaching the weld. Controlling it within this range ensures that the adhesive overflowing from the outer dam 53 can be accurately guided to the root of the weld, avoiding both insufficient adhesive leading to seal failure and excessive adhesive contaminating the inner wall of the casing 31.

[0072] d3≤100μm: This size limit further optimizes the compactness of the dam system, ensuring that the inner dam 51 plays a positioning assistance role in a limited space, while not interfering with the flow field of the external adhesive.

[0073] The organic combination of the above-mentioned rheological properties and geometric parameters ensures that the sealant 6, when liquefied and flowing, can smoothly and densely fill the weld between the shell 31 and the substrate 1 under the dual drive of capillary action and surface tension, while preventing the uncontrollable spread of the adhesive, and finally achieving highly reliable self-sealing inorganic encapsulation.

[0074] Furthermore, to optimize the adhesive blocking effect, the height h2 of the central dam 52 is greater than the inner ring height h5 of the positioning notch 43. This ensures that the adhesive inside the central dam 52 is effectively blocked by the central dam 52, thereby filling the portion of the positioning notch 43 located inside the central dam 52, to achieve effective bonding between the reflector cup 4 and the welding layer 12.

[0075] As a preferred embodiment, such as Figure 6 As shown, the surface of the LED chip 2 can also be dot-coated with a UV-resistant optical coupling medium 7 to form an inverted trapezoidal structure encapsulating the LED chip 2, thereby reducing the interfacial refractive index difference and improving light extraction efficiency. Alternatively, as... Figure 7 As shown, the optical coupling medium 7 can completely fill the cavity formed by the reflector cup 4. Since there is a tiny gap between the reflector cup 4 and the optical window 3, the full-fill method facilitates venting to avoid air bubbles, and can also utilize the tiny gap to accommodate the thermal expansion of the optical coupling medium without leakage.

[0076] The optical coupling medium 7 is preferably made of fluorinated oil, but can also be made of fluororesin, amorphous fluoropolymer, or other UV-resistant transparent materials.

[0077] Example 2: Inorganic Sealing Method for LED Light Sources

[0078] This invention also discloses an inorganic sealing method for LED light sources, used to encapsulate the aforementioned self-sealing inorganic LED light source, comprising the following steps:

[0079] Step S1: Prepare materials, namely, the designed substrate 1, light window 3, reflector 4, LED chip 2, and sealant 6. The sealant 6 is an organic adhesive with temperature-controlled viscosity characteristics, such as stage B epoxy resin, silicone-modified phenolic resin, or polyurethane structural adhesive. Considering the deep ultraviolet environment, polyimide adhesive or low-volatile silicone is preferred for sealant 6.

[0080] Step S2 involves chip bonding, specifically die bonding (currently, deep ultraviolet LED chips mostly use high-temperature eutectic bonding, but solder paste, nano-silver paste, etc., can also be used) to bond the LED chip 2 to the electrode layer 11 of the substrate 1. The LED chip 2 is typically a flip-chip deep ultraviolet LED chip, and AuSn high-temperature eutectic bonding is used. Flux is applied before eutectic bonding, followed by heating in a vacuum eutectic furnace, and effective bonding is achieved after cooling. Alternatively, bonding materials with good conductivity and heat dissipation properties, such as nano-solder paste or SnAgCu eutectic solder, can also be used.

[0081] Step S3, dispensing: Sealant 6 is applied using a dispensing machine within the inner dam 51 and outer dam 53, forming a raised shape to cover the middle dam 52. Preferably, the highest point of the raised sealant 6 is higher than the position of the inner top surface 431 of the positioning notch 43 corresponding to the middle dam, to ensure that the sealant 6 contacts the inner top surface 431 when the reflector cup 4 is installed. At this time, the sealant 6 is at room temperature, with a viscosity of not less than 2000 mPa·s, exhibiting certain thixotropic properties to maintain its shape.

[0082] Step S4: Cover the reflector cup 4. After aligning the reflector cup 4, place it on the welding layer 12. Use the inner dam 51 in conjunction with the positioning notch 43 at the bottom of the reflector cup 4 to position the reflector cup 4. During the downward pressing of the reflector cup 4, the sealant 6 will come into contact with the inner top surface 431 of the positioning notch 43. The inner top surface 431 will press the excess sealant 6 into the internal gap of the positioning notch 43. The inclined inner top surface 431 design helps to increase the bonding area. The positioning notch 43 is located on the outer side of the middle dam 52. Due to its higher opening, the adhesive has a certain amount of compression space during the installation of the reflector cup 4, and its high viscosity prevents it from overflowing out of the outer dam.

[0083] Step S5, shaping treatment, involves shaping the sealant 6 (preferably heat treatment, but ultrasonic treatment is also possible) to initially shape it. For example, heating at 40-100℃ for 3-30 minutes can be used. It is worth noting that different sealant 6 materials require different heating conditions. At this point, the viscosity of the sealant 6 increases (not less than 5000 mPa·s), completing the initial bonding and fixation between the reflector cup 4 and the welding layer 12, and preventing adhesive displacement during subsequent laser sealing.

[0084] Step S5.5 (optional), such as Figure 6 As shown, before laser sealing, a UV-resistant optical coupling medium 7 (such as fluorinated oil, fluororesin, amorphous fluoropolymer, or other UV-resistant transparent materials) is dotted onto the surface of the LED chip 2 to form a certain inverted trapezoidal structure encapsulating the LED chip 2. This reduces the refractive index difference at the front light-emitting interface, improves light extraction efficiency, and the inverted trapezoidal optical coupling medium 7 also facilitates the upward extraction of side light. Figure 7 As shown, this step can also involve filling the cavity enclosed by the reflector cup 4 with the optical coupling medium 7. Because there is a small gap between the reflector cup 4 and the light window 3 (there is a gap between the top surface of the reflector cup 4 and the lens, and a gap between the outer surface of the reflector cup 4 and the inner surface of the tube shell 31), the amount of optical coupling medium is easier to control. It is less likely to cause the risk of bubbles being generated due to the lack of air vents when the optical coupling medium is completely filled, and it is also less likely to cause the risk of easy flow when only a small amount of optical coupling medium is added.

[0085] Step S6, sealing (preferably using a high-energy laser high-frequency dot welding process to melt the contact surface, or alternatively using AuSn eutectic solder, CuSn low-temperature brazing, or nano-AgCuTi low-temperature brazing solder placed between the horizontal part 312 and the substrate 1 and using the corresponding welding process to complete the sealing. Here, laser sealing is taken as an example), that is, the optical window 3 is positioned and pressed onto the substrate 1, so that the bottom of the tube shell 31 contacts the welding layer 12 on the upper surface of the substrate 1, and then the contact surface is melted by high-energy laser high-frequency dot welding, thereby achieving welding fixation. Since the laser energy is too high and cannot be continuously output, there is a risk of melting and reduced airtightness. Therefore, the sealing is carried out by high-frequency high-density dot welding.

[0086] Step S7, softening treatment, i.e., re-processing (preferably by heat treatment) the sealant 6 to soften it and reduce its viscosity (viscosity to no more than 4000 mPa·s), making the sealant 6 thinner and more fluid. The processing conditions are controlled so that the sealant 6 outside the middle dam 52 flows over the outer dam 53 to the contact position between the pipe shell 31 and the weld layer 12, filling the gap left by the laser sealing weld to achieve an airtight seal. The heating conditions can be performed using a treatment scheme of heating at 80-150℃ for 10-60 minutes. It is worth noting that the heating conditions vary depending on the sealant 6 material.

[0087] Since the outer dam 53 is close to the contact point between the shell 31 and the substrate 1, it can fill the gap at the contact point and effectively cover the contact surface between the shell 31 and the substrate 1 under the action of capillary action and surface adhesion, thus achieving a seal.

[0088] In addition, due to the high height of the central dam and the low height of the inner side of the positioning notch 43, and due to the surface tension of the adhesive, the sealant 6 inside the central dam will not flow, thus ensuring that the bonding of the reflector cup 4 is not affected.

[0089] Due to the shielding effect of the reflector cup 4, even though the sealant 6 is an organic material, the deep ultraviolet radiation it receives is extremely weak, thus ensuring long-term reliability.

[0090] Step S8, sealant curing: After the sealant 6 has flowed and filled evenly, the processing conditions are changed (e.g., the heat treatment conditions) to allow the sealant 6 to fully cure, thus achieving the bonding and fixation of the reflector cup 4 and the sealing of the connection between the tube shell 31 and the weld layer 12. The heating conditions can be implemented using a treatment scheme of heating at 120-180℃ for 30-120 minutes. It is worth noting that the heating conditions differ depending on the sealant 6 material.

[0091] It is worth noting that, generally speaking, deep ultraviolet LED packaging cannot contain organic materials, mainly because organic materials will decompose and deform under deep ultraviolet irradiation, leading to failure. However, this invention uses a reflector cup with a very small gap between it and the light window. Even if a little light leaks through the small gaps at the edges of the lens and reflector cup, it will be absorbed by the light window and reflector cup, with almost no light reaching the bottom of the reflector cup. This ensures the long-term use of the organic material (i.e., sealant 6). Furthermore, considering the volatilization during the curing process, the sealant 6 of this invention can preferably be made of non-volatile or almost non-volatile materials such as polyimide adhesive or silicone adhesive, thus ensuring environmental friendliness.

[0092] 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 self-sealing inorganic LED light source, characterized in that: The device includes a substrate (1), an LED chip (2), and a light window (3). The top surface of the substrate (1) is provided with an electrode layer (11) and a welding layer (12) surrounding the electrode layer (11). The LED chip (2) is welded to the electrode layer (11). The light window (3) includes a housing (31) surrounding the LED chip (2) and a lens (32) welded to the top opening of the housing (31). The lower end of the housing (31) is welded to the welding layer (12). The tube shell (31) is provided with a ring-shaped reflector cup (4) surrounding the LED chip (2). The outer side of the bottom surface of the reflector cup (4) is provided with a positioning notch (43) with the opening facing outward. The corresponding position of the welding layer (12) is provided with a positioning dam (5) for cooperating with the positioning notch (43) to position the reflector cup (4). The positioning dam (5) is provided with sealant (6) for bonding and fixing the reflector cup (4). Part of the sealant (6) overflows to the connection between the tube shell (31) and the welding layer (12) and seals it. The positioning dam (5) includes an inner dam (51), a middle dam (52) and an outer dam (53) arranged sequentially from the inside to the outside, and satisfies that the height h2 of the middle dam (52) > the height h1 of the inner dam (51) ≥ the height h3 of the outer dam (53); The positioning notch (43) has an inner top surface (431), which is a sloping surface that gradually slopes outward from bottom to top.

2. The self-sealing inorganic LED light source according to claim 1, characterized in that: The inner side of the reflector cup (4) is a first reflective surface (41) that gradually slopes outward from bottom to top. A reflective layer is provided on the first reflective surface (41), which is an inclined or arc-shaped surface. The top surface of the reflector cup (4) is a second reflective surface (42), which is also provided with a reflective layer. The second reflective surface (42) and the bottom surface of the lens (32) are spaced apart.

3. The self-sealing inorganic LED light source according to claim 1, characterized in that: The inclination angle α of the inner top surface (431) relative to the horizontal plane is not less than 15°.

4. The self-sealing inorganic LED light source according to claim 1, characterized in that: The cross-section of the positioning notch (43) is a sideways trapezoidal shape, with an outer ring height of h4, an inner ring height of h5, and a radial width of l; the cross-section of the reflector cup (4) has a height of H and a width of L, satisfying the following conditions: h4≤1 / 2H, h5≤1 / 3H, l≤1 / 2L.

5. The self-sealing inorganic sealing LED light source according to claim 4, characterized in that: The height h2 of the central dam (52) is greater than the inner ring height h5 of the positioning gap (43).

6. The self-sealing inorganic LED light source according to claim 4, characterized in that: There is a gap d1 between the outer wall of the reflector cup (4) and the inner wall of the shell (31), a gap d2 between the outer dam (53) and the inner wall of the shell (31), and a gap d3 between the inner dam (51) and the inner ring of the positioning notch (43), wherein the following conditions are met: 50μm≤d1≤300μm, 50μm≤d2≤200μm, and d3≤100μm.

7. The self-sealing inorganic LED light source according to claim 1, characterized in that: The surface of the LED chip (2) is covered with an optical coupling medium (7), which is an inverted trapezoidal structure that encloses the LED chip (2), or the optical coupling medium (7) is filled in the cavity formed by the reflector (4).

8. An inorganic sealing method for LED light sources, used for encapsulating the self-sealing inorganic LED light source according to any one of claims 1-7, characterized in that, Includes the following steps: Step S1: Prepare materials, namely, prepare the designed substrate (1), light window (3), reflector (4), LED chip (2), and sealant (6). Step S2, welding the chip, that is, using the die bonding method to weld the LED chip (2) onto the electrode layer (11) of the substrate (1); Step S3, dispensing, that is, applying sealant (6) to the inner dam (51) and outer dam (53) with a dispensing machine, and making the sealant (6) form a raised shape to cover the middle dam (52). Step S4, cover the reflector cup (4), that is, after aligning the reflector cup (4) in the correct position, place it on the welding layer (12), and use the inner dam (51) in conjunction with the positioning notch (43) at the bottom of the reflector cup (4) to position the reflector cup (4). During the process of pressing down the reflector cup (4), the sealant (6) will contact the inner top surface (431) of the positioning notch (43), and the inner top surface (431) will press the excess sealant (6) into the gap inside the positioning notch (43). Step S5, shaping treatment, that is, shaping treatment of the sealant (6) to make it initially shaped; Step S6, sealing, that is, positioning and pressing the light window (3) onto the substrate (1), so that the bottom of the tube shell (31) contacts the welding layer (12) on the upper surface of the substrate (1), and then sealing the light window (3) to achieve welding and fixing. Step S7, softening treatment, that is, treating the sealant (6) to soften it and reduce its viscosity, controlling the treatment conditions so that the sealant (6) outside the middle dam (52) crosses the outer dam (53), flows to the contact position between the pipe shell (31) and the weld layer (12) and fills the gap; Step S8, sealant curing, that is, after the sealant (6) has flowed and filled evenly, the processing conditions are changed to make the sealant (6) completely cured, so as to achieve the bonding and fixing of the reflector cup (4) and the sealing of the connection between the tube shell (31) and the welding layer (12).

9. The inorganic sealing method for an LED light source according to claim 8, characterized in that, The following steps are also included between step S5 and step S6: Step S5.5: Apply UV-resistant optical coupling medium (7) to the surface of the LED chip (2) to form an inverted trapezoidal structure that encloses the LED chip (2), or fill the cavity enclosed by the reflector (4) with optical coupling medium (7).

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