LED lamp bead

Abstract

The LED lamp bead comprises a substrate, an LED chip and a convex lens light window, the substrate comprises a ceramic plate, copper circuit layers and a copper plating layer, the copper circuit layers are arranged on the top face and the bottom face of the ceramic plate and are communicated with each other, the copper plating layer is arranged on the top face of the ceramic plate, and the LED chip is connected to the copper circuit layer on the top face of the ceramic plate. The convex lens light window comprises a convex lens and a metal ring which is arranged on the periphery of the convex lens and has certain elasticity, the bottom face of the metal ring is connected with the copper plating layer, and a clamping groove used for clamping and fixing the convex lens is formed in the upper end of the inner side face of the metal ring. The clamping groove is provided with a bearing plane attached to the bottom face of the convex lens and an arc-shaped face attached to the lower portion of the side face of the convex lens. The utility model has the advantages of steadiness and low possibility of falling off.

Description

Technical Field

[0001] The utility model relates to the technical field of LED lamps, in particular to an LED lamp bead. Background Art

[0002] With the rapid development and wide application of LED lighting technology, LED lamps have gradually become the mainstream products in the lighting industry due to their advantages such as high energy efficiency, long service life, fast response speed, and small size. Among the core components of LED lamps, the structural design and performance of LED lamp beads directly affect the optical performance, service life, and reliability of the entire lamp.

[0003] Currently, the common LED lamp bead structures on the market mainly include a substrate, an LED chip, and a convex lens light window. In the prior art, the connection structure between the convex lens and the substrate is often unreasonably designed and cannot effectively cope with the stress changes caused by thermal expansion and contraction. After long-term use, it is easy to cause structural loosening and sealing failure. Especially in the application scenarios of large-size convex lenses, due to the large volume of the convex lens but a small fixed area, the convex lens is more likely to separate from the substrate under equipment vibration or accidental collision, seriously affecting the service life and reliability of the LED lamp bead.

[0004] Therefore, it is necessary to further improve and perfect the prior art to overcome these deficiencies, and the present utility model is made based on this situation. Summary of the Utility Model

[0005] The purpose of the present utility model is to overcome the deficiencies of the prior art and provide an LED lamp bead that is stable and not easily detached.

[0006] The present utility model is realized through the following technical solutions:

[0007] To solve the above technical problems, the present utility model provides an LED lamp bead, including a substrate, an LED chip, and a convex lens light window. The substrate includes a ceramic plate, copper circuit layers provided on the top and bottom surfaces of the ceramic plate and electrically connected to each other, and a copper plating layer provided on the top surface of the ceramic plate. The LED chip is connected to the copper circuit layer on the top surface of the ceramic plate. The convex lens light window includes a convex lens and a metal ring provided around the convex lens and having a certain elasticity. The bottom surface of the metal ring is connected to the copper plating layer. The upper end of the inner side surface of the metal ring is provided with a card slot for clamping the convex lens. The card slot has a supporting plane that fits the bottom surface of the convex lens and an arc surface that fits the lower part of the side surface of the convex lens.

[0008] To further solve the technical problems to be solved by the present utility model, in an LED lamp bead provided by the present utility model, a welding layer is further provided on the contact surface between the card slot and the convex lens.

[0009] In order to further solve the technical problems to be solved by the present utility model, in an LED lamp bead provided by the present utility model, the welding layer uses an inorganic glass solder or a low-temperature metal alloy solder.

[0010] In order to further solve the technical problems to be solved by the present utility model, in an LED lamp bead provided by the present utility model, a positioning dam surrounding the LED chip is provided on the copper plating layer, and the outer side surface of the positioning dam abuts against the inner side surface of the metal ring.

[0011] In order to further solve the technical problems to be solved by the present utility model, in an LED lamp bead provided by the present utility model, the inner side surface of the positioning dam is an inclined surface that gradually inclines outward from bottom to top.

[0012] In order to further solve the technical problems to be solved by the present utility model, in an LED lamp bead provided by the present utility model, the height m of the positioning dam is not higher than the height n of the LED chip.

[0013] In order to further solve the technical problems to be solved by the present utility model, in an LED lamp bead provided by the present utility model, the diameter w of the upper opening of the metal ring is smaller than the diameter D of the bottom surface of the convex lens.

[0014] In order to further solve the technical problems to be solved by the present utility model, in an LED lamp bead provided by the present utility model, the convex lens is an inverted hemispherical shape.

[0015] In order to further solve the technical problems to be solved by the present utility model, in an LED lamp bead provided by the present utility model, the relationship between the height h between the top of the metal ring and the bottom surface of the convex lens and the height L of the convex lens satisfies: 1 / 3L > h > 1 / 5L.

[0016] In order to further solve the technical problems to be solved by the present utility model, in an LED lamp bead provided by the present utility model, the bottom of the metal ring is provided with an outwardly extending edge.

[0017] Compared with the prior art, the present utility model has the following advantages:

[0018] The LED lamp bead of the present utility model provides a reliable, flexible and easy-to-realize mass-production fixing solution for the convex lens optical window. By ingeniously designing a metal ring with a specific slot structure, which is connected to the substrate and uses the design that the upper opening size is smaller than the bottom diameter of the convex lens, firm and rigid mechanical clamping of the convex lens is achieved. This core innovation significantly improves the reliability of lens fixing and effectively solves the problems of loosening or falling off that may be faced by traditional bonding methods. The optionally provided positioning dam effectively ensures the precise alignment of the lens and the chip and protects the chip area from pollutants, and the inclined inner side surface design also helps to optimize the light extraction efficiency. Brief Description of the Drawings

[0019] Figure 1 is a schematic cross-sectional view of the present utility model;

[0020] Figure 2 is a schematic cross-sectional view of the convex lens light window;

[0021] Figure 3 is a schematic cross-sectional view of the substrate;

[0022] Figure 4 is the light intensity distribution diagram of the light emitted by a light source with a half-intensity angle of 60°;

[0023] Figure 5 is the light intensity distribution diagram of the light emitted by a light source with a half-intensity angle of 90°;

[0024] Figure 6 is the schematic diagram of the bayonet top height of the metal ring and the light output distribution. Detailed Embodiment

[0025] In order to enable those skilled in the art to better understand the technical solution of the present utility model, the present utility model will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0026] As Figures 1 to 3 shown, the present utility model provides an LED lamp bead. The LED lamp bead has a compact structure, is stable and reliable, and is particularly suitable for deep ultraviolet (DUV) application scenarios. The LED lamp bead mainly includes: a substrate 1, an LED chip 2 disposed on the substrate 1, and a convex lens light window 3 fixed on the substrate 1 and covering the LED chip 2.

[0027] The substrate 1 is used to carry the LED chip 2, provide an electrical connection path and a heat dissipation path. The substrate 1 includes a ceramic plate 11. In order to achieve upper and lower circuit connection and effective heat conduction, copper circuit layers 12 are provided on both the top surface and the bottom surface of the ceramic plate 11, and the copper circuit layers 12 on the top surface and the bottom surface are electrically and thermally conducted through circuit vias 121 provided inside the ceramic plate 11. On the top surface of the ceramic plate 11, a copper plating layer 13 is further provided around the LED chip 2. This copper plating layer 13 is mainly used for subsequent connection and fixation with the fixing structure (such as a metal ring 32) of the convex lens light window 3 and plays a certain reflection role. The ceramic plate 11 is usually made of a ceramic material with good thermal conductivity and electrical insulation properties, such as but not limited to aluminum nitride (AlN) ceramic or alumina (Al2O3) ceramic.

[0028] The LED chip 2 is disposed on the copper circuit layer 12 on the top surface of the substrate 1, and it is the light-emitting source of the lamp bead. In this embodiment, the LED chip 2 preferably adopts a deep ultraviolet LED chip, which can emit ultraviolet light within a specific wavelength range, such as for applications like sterilization and disinfection.

[0029] Next, the key part of the present invention - the fixing structure of the convex lens light window 3 will be described in detail.

[0030] The convex lens light window 3 is used to shape, focus or diffuse the light emitted by the LED chip. The convex lens light window 3 includes an inverted hemispherical or quasi-hemispherical convex lens 31, and a metal ring 32 provided around the convex lens 31 and having a certain elasticity. The convex lens 31 is usually made of a material with high light transmittance in the deep ultraviolet band to ensure effective transmission of light energy. Preferred materials include quartz convex lenses, sapphire convex lenses, or high-transmittance glass convex lenses designed specifically for this band.

[0031] The metal ring 32 is the key structure connecting the convex lens 31 and the substrate 1. The bottom surface of the metal ring 32 is connected and fixed to the copper plating 13 on the top surface of the substrate 1 (by welding or bonding). The upper end of its inner side is provided with a card slot 321 for clamping the convex lens 31. The shape of the card slot 321 is designed according to the bottom edge of the convex lens 31, specifically including a supporting plane 3211 that fits the bottom edge of the convex lens 31, and an arc surface 3212 that fits the lower part of the side surface of the convex lens 31.

[0032] This design forms a relatively large contact area through the contact between the supporting plane 3211 and the arc surface 3212 of the card slot 321 and the convex lens 31. More importantly, the metal ring 32 firmly clamps the edge of the convex lens 31 in the card slot through its structural characteristics (for example, through the necking process as described later). This mechanical clamping method can effectively fix the convex lens 31 in place, greatly avoiding the loosening or falling off of the convex lens 31 during use due to reasons such as vibration, thermal expansion and contraction.

[0033] As Figure 1 shown, in some application environments, such as when the LED lamp bead is integrally sealed in a lamp tube or a larger cavity for application, when the airtightness requirement for a single LED lamp bead itself is not high, relying only on the physical clamping of the convex lens 31 by the metal ring 32 can fully ensure that the lens will not fall off, and the structure is very reliable and the cost is relatively low.

[0034] As Figure 2As shown, for usage environments with high airtightness requirements, such as when the lamp beads themselves need to have vacuum or specific gas environment tightness, it is necessary to strengthen the connection between the metal ring 32 and the convex lens 31, as well as the connection between the metal ring 32 and the substrate 1. Specifically, in this embodiment, a welding layer 33 or an adhesive layer is further provided between the contact surfaces of the card slot 321 and the convex lens 31 to achieve airtight connection. The contact surfaces for bonding / welding include the side surface (i.e., the arc surface 3212) and the bottom surface (i.e., the supporting plane 3211) of the metal ring card slot and the contact areas at the corresponding positions of the convex lens. The selection of the welding or bonding material is crucial. Preferably, materials that can provide good airtightness and are compatible with the lens and metal ring materials are used. For example, inorganic glass solders with a certain toughness (such as bismuthate glass, phosphate glass, borosilicate glass, etc.) can be used. These solders form a dense glass phase after curing and have good airtightness. Or, low-temperature metal alloy solders (such as gold-tin alloy (AuSn), tin-silver-copper alloy (SnAgCu), tin-bismuth alloy (SnBi), etc.) can be used. These solders can complete welding at relatively low temperatures, reduce thermal stress, and can form reliable metal bonds to achieve sealing.

[0035] At the same time, the contact surface between the metal ring 32 and the copper plating layer 13 is also fixed by welding or bonding to achieve airtightness at the substrate level.

[0036] Furthermore, in order to expand the contact area between the bottom of the metal ring 32 and the copper plating layer 13 and improve the connection strength and airtightness, the bottom of the metal ring 32 is provided with an outwardly extending edge 322, which can also be vividly called a welding edge. The design dimensions of this edge 322 have an important impact on the connection process and airtightness. Preferably, the thickness of the edge 322 is designed between 50μm and 200μm, and the radial width of the welding edge is designed between 200μm and 400μm. Under these dimension design conditions, it is convenient to use conventional bonding / welding materials such as silver glue and solder paste for connection, and high-precision laser welding can also be achieved. At the same time, the larger width of the welding edge provides sufficient sealing tolerance space, which helps to achieve high-reliability airtight packaging with a high yield.

[0037] Regarding the material selection of the metal ring 32, it is particularly important for achieving high-airtightness welding. Preferably, the metal ring material is selected as an alloy with a small coefficient of thermal expansion (CTE) and easy to process, such as Kovar alloy, Invar alloy, Super Invar alloy, etc. Using such alloy systems, their coefficients of thermal expansion are close to those of lens materials such as glass, sapphire, and quartz. When welding (especially high-temperature welding), the stress generated due to the mismatch of material thermal expansion can be significantly reduced, thereby obtaining a stable, reliable, and high-airtight connection between the lens and the metal ring, and avoiding cracking or peeling of the sealing layer due to excessive stress.

[0038] On the basis of the foregoing embodiments, in order to further improve the positioning accuracy of the convex lens optical window 3 and protect the LED chip 2, a positioning structure may be provided on the substrate.

[0039] Furthermore, a positioning dam 4 (preferably a copper dam) surrounding the LED chip 2 may be provided on the copper plating layer 13. The outer side surface of the positioning dam 4 is designed to be in close contact with the inner side surface of the metal ring 32. This design enables the positioning dam 4 to provide precise radial positioning for the installation of the convex lens optical window 3 (including its metal ring 32), ensuring that the optical axis center of the convex lens can be accurately aligned with the light-emitting center of the LED chip, which is very important for optimizing the light-emitting angle and spot uniformity, and solves the problem that it is not easy to accurately align the convex lens during the installation process.

[0040] In addition, the positioning dam 4 also has an important auxiliary function. During the bonding or soldering process of the metal ring 32 and the copper plating layer 13, the positioning dam 4 can play a physical blocking role to prevent materials such as solder paste, silver glue, or flux from spreading to the LED chip area. This effectively protects the chip surface and the surrounding area from contamination, thereby suppressing the adverse effects that these materials may have on the light-emitting efficiency and long-term use reliability of the LED chip.

[0041] Preferably, the inner side surface of the positioning dam 4 (i.e., the side facing the LED chip 2) is an inclined surface 41 that gradually slopes outward from bottom to top. The inclination angle formed by the inclined surface 41 and the top surface of the substrate is preferably set in the range of 45° ± 5°. Although the reflectivity of the copper plating layer 13 itself is not particularly high, combined with the inclined surface shape of the positioning dam 4, the light emitted laterally by the LED chip can be deflected. If a high-reflection layer (such as a rhodium or aluminum reflective film) needs to be provided on the surface of the inclined surface 41, then the inclined surface 41 can more effectively deflect the light emitted laterally by the chip upward and guide it into the light-emitting angle range of the convex lens 31, thereby improving the overall light extraction efficiency. The angle design of the inclined surface 41 (such as being close to 45 degrees) helps to reflect the lateral light upward and reduce the proportion absorbed by the sidewall or blocked by the metal ring.

[0042] More preferably, the height m of the positioning dam 4 is designed to be not higher than the height n of the LED chip 2. This is to ensure that when installing the convex lens optical window 3, the top of the positioning dam 4 will not come into contact with the bottom edge of the convex lens 31, ensuring that the convex lens optical window can be successfully and accurately positioned and clamped by the metal ring, avoiding installation difficulties or causing structural stress.

[0043] On the basis of the foregoing embodiments, the size design for how the metal ring achieves reliable clamping is further defined in detail later.

[0044] Such as Figure 1As shown, in order to ensure that the metal ring 32 can firmly hold the convex lens 31 without falling off, the inner diameter w of the upper opening of the metal ring 32 must be smaller than the maximum diameter D of the bottom surface of the convex lens 31. In the actual manufacturing process, usually the upper opening of the metal ring 32 is pre-made slightly larger than the bottom diameter of the convex lens 31 to facilitate putting the convex lens 31 into the card slot 321 of the metal ring. Subsequently, the upper end of the metal ring 32 is processed by mechanical means (such as stamping, necking die) to make the inner diameter w of its upper opening smaller, and finally meet the relationship of w < D. In this way, the upper opening of the metal ring 32 will be like an "inverted hook" and tightly hold the bottom edge of the convex lens 31 to achieve the hard physical fixation of the convex lens 31.

[0045] Furthermore, the present utility model optimally defines the relationship between the height h of the metal ring 32 holding the convex lens 31 (that is, the vertical height between the top end of the metal ring 32 and the bottom surface of the convex lens 31) and the overall height L of the convex lens 31. This relationship satisfies: 1 / 3L > h > 1 / 5L. The design of this height range is based on the comprehensive consideration of light output efficiency and clamping reliability.

[0046] The test principle of the far-field light intensity angular distribution is as follows: At a distance far from the light source, a test is set up that can rotate around the light source as the center point from -90° to 90° (the angle with the normal line of the light source plane). Because the distance between the detector and the light source is many times larger than the size of the light source (far-field test), the influence of the internal size of the light source and the light output optical path can be ignored.

[0047] In the embodiment of the present utility model, the far-field light intensity angular distribution test as shown in Figures 4 - 5 is adopted. In the figure, the dark semi-circular line is the position corresponding to 50% of the half-intensity, the arrow is the position of the half-intensity corresponding light ray, and the included angle θ between the two light rays is the light output half-intensity angle range. For a typical convex lens light source, the light emitted by the LED chip is refracted by the lens, and its light intensity is mainly concentrated in the central area to form a main light spot. As shown in Figure 6 in the figure, in the range with a relatively large light output angle (for example, corresponding to the angle α greater than 70° between the light ray emitted from the center of the chip and refracted by the lens edge and the light output optical axis Y-axis, that is, the angle β of the light output range greater than 140°), the proportion of the light intensity in the total intensity is very small, usually less than 2%.

[0048] The height h of the bayonet top of the metal ring (that is, the vertical height between the top end of the metal ring 32 and the bottom surface of the convex lens 31) determines the range of the metal ring covering the lens edge. Setting h within the range covering this small part of low-intensity light is acceptable, and even the main light spot shape can be optimized by blocking this part of stray light, while reducing the use of metal materials. As shown in Figure 6As shown, corresponding to the height L of the convex lens, a height of approximately 1 / 3L roughly corresponds to the position where light rays emitted from the center of the chip, after refraction at the edge of the lens, form an angle γ1 of about 20° with the horizontal plane (i.e., α1 is approximately equal to 70°, or the angle of the light-emitting range is approximately equal to 140°). Therefore, limiting h to less than 1 / 3L can avoid blocking most of the effective light intensity.

[0049] Meanwhile, to ensure that the metal ring 32 can reliably hold the convex lens 31 (i.e., ensure that after the necking process, the inner diameter w of the upper end of the metal ring is always smaller than the bottom diameter D of the lens), the height h of the top of the bayonet needs to be higher than a minimum value. This minimum value needs to take into account the shape of the lens and the tolerance of the necking process. As Figure 6 shown, for a typical lens shape, a height of 1 / 5L approximately corresponds to the position where light rays emitted from the center of the chip, after refraction at the edge of the lens, form an angle γ2 of approximately equal to 11.5° with the horizontal plane (i.e., α2 is approximately equal to 78.5°, or the angle of the light-emitting range is approximately equal to 167°). Setting h higher than 1 / 5L can ensure that the metal ring has enough "hook" on the edge part of the lens after necking, and there is a certain process margin. Even with manufacturing tolerances, it can effectively ensure w < D and achieve a stable clamping.

[0050] Therefore, limiting the height h of the top of the metal ring bayonet to the range of 1 / 5L to 1 / 3L can not only ensure reliable mechanical clamping of the convex lens but also minimize the impact on the main light beam, achieving the best balance between performance and structural stability.

Claims

1. An LED lamp bead, characterized in that: It includes a substrate (1), an LED chip (2) and a convex lens optical window (3). The substrate (1) includes a ceramic plate (11), copper circuit layers (12) provided on the top and bottom surfaces of the ceramic plate (11) and electrically connected to each other, and a copper plating layer (13) provided on the top surface of the ceramic plate (11). The LED chip (2) is connected to the copper circuit layer (12) on the top surface of the ceramic plate (11). The convex lens optical window (3) includes a convex lens (31) and a metal ring (32) provided around the convex lens (31) and having a certain elasticity. The bottom surface of the metal ring (32) is connected to the copper plating layer (13). An upper end of an inner side surface of the metal ring (32) is provided with a clamping groove (321) for clamping the convex lens (31). The clamping groove (321) has a supporting plane (3211) that fits the bottom surface of the convex lens (31) and an arc surface (3212) that fits the lower part of the side surface of the convex lens (31).

2. The LED lamp bead according to claim 1, characterized in that: A welding layer (33) is further provided on a contact surface between the clamping groove (321) and the convex lens (31).

3. An LED lamp bead according to claim 2, characterized in that: The welding layer (33) is made of an inorganic glass solder or a low-temperature metal alloy solder.

4. An LED lamp bead according to claim 1, characterized in that: A positioning dam (4) surrounding the LED chip (2) is provided on the copper plating layer (13). An outer side surface of the positioning dam (4) abuts against an inner side surface of the metal ring (32).

5. An LED lamp bead according to claim 4, characterized in that: An inner side surface of the positioning dam (4) is an inclined surface (41) that gradually inclines outward from bottom to top.

6. An LED lamp bead according to claim 4, characterized in that: A height m of the positioning dam (4) is not higher than a height n of the LED chip (2).

7. An LED lamp bead according to claim 1, characterized in that: A diameter w of an upper end opening of the metal ring (32) is smaller than a diameter D of the bottom surface of the convex lens (31).

8. An LED lamp bead according to claim 1, characterized in that: The convex lens (31) is an inverted hemispherical shape.

9. An LED lamp bead according to claim 1, characterized in that: A relationship between a height h between a top end of the metal ring (32) and a bottom surface of the convex lens (31) and a height L of the convex lens (31) satisfies: 1 / 3L > h > 1 / 5L.

10. An LED lamp bead according to claim 1, characterized in that: An edge (322) extending outward is provided at a bottom of the metal ring (32).

Images