High-efficiency deep ultraviolet LED light source

Abstract

The utility model discloses a high-efficiency deep ultraviolet LED light source which comprises a support, an LED chip, a reflection cup and a light window covering the LED chip and the reflection cup, the support comprises a substrate, an electrode bonding pad arranged on the upper surface of the substrate, a support bonding pad arranged on the lower surface of the substrate and electrically connected with the electrode bonding pad, and a welding layer arranged on the periphery of the electrode bonding pad, the LED chip is welded on the electrode bonding pad, the reflecting cup is annular and surrounds the periphery of the LED chip, the inner side of the reflecting cup is provided with a reflecting surface which is gradually raised from inside to outside, the upper surface of the substrate is also provided with a positioning box dam, and the bottom surface of the reflecting cup is provided with a positioning notch which is mutually matched with the positioning box dam. The utility model has the advantage that the light extraction efficiency is easily improved on the basis of the existing inorganic packaging.

Description

Technical Field

[0001] This utility model relates to the field of LED light source technology, and in particular to a high-efficiency deep ultraviolet LED light source. Background Technology

[0002] Currently, deep ultraviolet (DUV) LED light sources have broad application prospects in sterilization, medical treatment, and scientific research. However, with the continuous increase in the power of DUV LEDs, their reliability issues are becoming increasingly prominent. Traditional semi-inorganic packaging structures, containing organic materials that are easily aged by deep ultraviolet light, struggle to meet application requirements in terms of reliability. Therefore, the development trend of DUV LED packaging technology is towards inorganic packaging.

[0003] However, existing inorganic packaging structures for deep ultraviolet (DUV) LEDs are relatively complex and costly. Furthermore, a key characteristic of DUV LED chips is their strong lateral light emission. For example... Figure 1 As shown, existing inorganically packaged deep ultraviolet (DUV) LED light source structures typically include a ceramic support, electrode pads, a bonding layer, and an inorganic optical window. The DUV LED chip is bonded to the electrode pads, and the inorganic optical window is bonded to the bonding layer. Because the DUV LED chip emits strong light from its sides, when large-angle light rays are incident on the lens surface, according to Fresnel's law, most of the light is reflected, and the reflected light is easily absorbed by the metal casing. Furthermore, even larger-angle side-emitting light is directly absorbed by the casing. These factors result in a large amount of large-angle light rays not being effectively extracted, severely affecting the light extraction efficiency of the inorganic packaging structure. Figure 7 As shown. Therefore, there is an urgent need for a solution that can improve the structured light extraction efficiency of deep ultraviolet LED inorganic packaging. Utility Model Content

[0004] The purpose of this invention is to overcome the shortcomings of the prior art and provide a high-efficiency deep ultraviolet LED light source that can easily improve light extraction efficiency based on existing inorganic packaging.

[0005] This utility model is achieved through the following technical solution:

[0006] To solve the above-mentioned technical problems, this utility model provides a high-efficiency deep ultraviolet LED light source, including a bracket, an LED chip, a reflector cup, and a light window covering the LED chip and the reflector cup. The bracket includes a substrate, electrode pads on the upper surface of the substrate, bracket pads on the lower surface of the substrate and electrically connected to the electrode pads, and a welding layer on the outer periphery of the electrode pads. The LED chip is welded to the electrode pads. The reflector cup is annular and surrounds the LED chip. The inner side of the reflector cup has a reflective surface that gradually rises from the inside to the outside. The upper surface of the substrate is also provided with a positioning dam, and the bottom surface of the reflector cup has a positioning notch that cooperates with the positioning dam.

[0007] In order to further solve the technical problems to be solved by the utility model, the utility model provides a kind of high-efficiency deep ultraviolet LED light source, the reflecting surface of the reflecting cup and its top surface are coated with first reflecting layer, and its reflectivity is not less than 80%.

[0008] In order to further solve the technical problems to be solved by the utility model, the utility model provides a kind of high-efficiency deep ultraviolet LED light source, the reflecting surface is inclined plane or arc surface;When the reflecting surface is inclined plane, the range of its inclination C is 25 °-55 °.

[0009] In order to further solve the technical problems to be solved by the utility model, the utility model provides a kind of high-efficiency deep ultraviolet LED light source, the upper surface of the substrate is equipped with support layer, the positioning dam is integrally arranged on support layer, and the bottom surface of the reflecting cup is fixed on the positioning dam by bonding.

[0010] In order to further solve the technical problems to be solved by the utility model, the utility model provides a kind of high-efficiency deep ultraviolet LED light source, the electrode pad extends outward, the positioning dam is integrally arranged on electrode pad, the bottom surface of the reflecting cup is fixed on the positioning dam by bonding, and the reflecting cup is insulated.

[0011] In order to further solve the technical problems to be solved by the utility model, the utility model provides a kind of high-efficiency deep ultraviolet LED light source, the positioning dam is directly arranged on the upper surface of the substrate, and the bottom surface of the reflecting cup is fixed on the positioning dam by bonding;The height of the positioning dam is consistent with the height of electrode pad and welding layer.

[0012] In order to further solve the technical problems to be solved by the utility model, the utility model provides a kind of high-efficiency deep ultraviolet LED light source, the positioning notch has inner top surface gradually rising from inside to outside, for extruding glue outward when pasting.

[0013] In order to further solve the technical problems to be solved by the utility model, the utility model provides a kind of high-efficiency deep ultraviolet LED light source, the lower end of the reflecting surface on the reflecting cup has vertical step, and the height h1 of the step is not higher than the height h2 of electrode pad.

[0014] In order to further solve the technical problems to be solved by the utility model, the utility model provides a kind of high-efficiency deep ultraviolet LED light source, the surface of the electrode pad is coated with second reflecting layer, and its reflectivity is not less than 80%, and the position of chip electrode and zener electrode is not coated.

[0015] In order to further solve the technical problems to be solved by the utility model, the utility model provides a kind of high-efficiency deep ultraviolet LED light source, the light window includes annular enclosure, lens being arranged at the top of enclosure, solder ring is arranged between the upper end of enclosure and the periphery of lens, the front and back of lens are both provided with antireflection film.

[0016] Compared with prior art, the utility model has the following advantages:

[0017] 1.The high-efficiency deep ultraviolet LED light source of the utility model introduces annular reflecting cup, which is arranged around the periphery of LED chip, and has a reflecting surface gradually rising from inside to outside on the inner side, which can reflect the light emitted laterally by the LED chip to the lens of the light window, significantly reducing the absorption of light in the support and the light window, thereby effectively improving the light extraction efficiency.

[0018] 2.In order to realize the accurate positioning of the reflecting cup, the utility model sets a positioning dam on the upper surface of the substrate, and sets a positioning notch on the bottom surface of the reflecting cup, which cooperates with the positioning dam. Through this structure design, the relative position of the reflecting cup and the LED chip can be ensured, so that the size, shape and position of the reflecting cup correspond to the angle distribution of the light intensity of the chip, thereby realizing the best light extraction effect.

[0019] 3.The structure of the reflecting cup is also optimized in the utility model, and a vertical step is arranged at the bottom of the reflecting surface of the reflecting cup, and the height of the step is controlled within a certain range, which is convenient for processing and manufacturing.

[0020] 4.The inner top surface of the positioning notch is inclined, which facilitates the glue to be as far as possible to the outside when gluing and pasting on the positioning dam, so as to avoid that too much glue lifts up the reflecting cup. In addition, the inclined inner top surface can also increase the contact area of the glue and the reflecting cup, and improve the adhesion.

[0021] 5.The utility model coats high-reflective plating layer on the surface of electrode pad, further improving the light reflection efficiency. BRIEF DESCRIPTION OF DRAWINGS

[0022] The specific embodiments of the utility model will be further described in detail below in combination with the drawings, in which:

[0023] Figure 1 It is a structural schematic diagram of prior art;

[0024] Figure 2 It is a sectional view schematic diagram of the embodiment one of the utility model;

[0025] Figure 3 It is a sectional view schematic diagram of the embodiment two of the utility model;

[0026] Figure 4 It is a sectional view schematic diagram of the embodiment three of the utility model;

[0027] Figure 5 is Figure 2 a local enlarged view of B in figure 1;

[0028] Figure 6 is a top view of the bracket of embodiment one;

[0029] Figure 7 is a graph of the relationship between the exit angle and the light intensity of a small-size LED chip;

[0030] Figure 8 is a graph of the relationship between the exit angle and the light intensity of a large-size LED chip. DETAILED DESCRIPTION

[0031] In order for those skilled in the art to better understand the technical scheme of the present application, the present application will be further described in detail below in combination with the drawings and specific embodiments.

[0032] As Figures 2 to 6 shown, the present application provides a high-efficiency deep-ultraviolet LED light source, aiming to simply realize the purpose of improving light extraction efficiency on the basis of existing inorganic packaging. It mainly includes a bracket, an LED chip 1, a reflecting cup 2, and a light window 3 covering the LED chip 1 and the reflecting cup 2. Among them, the LED chip 1 is preferably a deep-ultraviolet LED chip to meet the demand of deep-ultraviolet application.

[0033] The bracket is the supporting structure of the entire light source, which includes a substrate 4 and a circuit layer. The circuit layer includes an electrode pad 5, a bracket pad 6, and a welding layer 7. The substrate 4 is preferably made of ceramic material, which has good insulation and heat dissipation performance. The electrode pad 5 is arranged on the upper surface of the substrate 4 and is used for die bonding and welding of the LED chip 1, that is, the LED chip 1 is welded on the electrode pad 5. The bracket pad 6 is arranged on the lower surface of the substrate 4 and is electrically connected with the electrode pad 5 through a circuit lead wire, which is used for welding with an external circuit to realize the connection of the power supply. The welding layer 7 is arranged on the outer periphery of the electrode pad 5 and is used to provide support for the welding of the light window 3 and the substrate 4, ensuring the reliability of the packaging. The welding layer 7 usually adopts a metal layer with a certain thickness plated on the surface of the substrate 4, including but not limited to copper. In order to simplify the process flow and improve the production efficiency, the electrode pad 5, the bracket pad 6, and the welding layer 7 are preferably formed by plating a metal layer on the surface of the substrate 4 and etching channels through an etching process.

[0034] In order to improve the light extraction efficiency, the present application introduces the reflecting cup 2. The reflecting cup 2 is in a ring structure and is arranged around the periphery of the LED chip 1.

[0035] The height of the reflecting cup 2 is slightly higher than that of the chip. The inner side of the reflecting cup 2 has a reflecting surface 21 gradually rising from inside to outside, which is used to reflect the light emitted laterally by the LED chip 1 to the lens of the light window 3, thereby reducing the absorption of the light in the support and the light window. The reflecting surface 21 is coated with a first reflecting layer 211, and the reflectivity of the first reflecting layer 211 is not less than 80%, preferably more than 90%, so as to ensure good reflecting effect. Preferably, as shown in Figure 2 the top surface of the reflecting cup 2 (denoted as cup top surface 24) is also coated with the first reflecting layer 211, and the light is further reflected.

[0036] The first reflecting layer 211 is preferably a metal reflecting layer, and is further preferably an Al (aluminum) reflecting layer. In consideration of the chemical stability of aluminum, the outer surface of the Al reflecting layer can be further provided with a high light-transmitting protective layer, such as silicon oxide, magnesium fluoride, calcium fluoride, etc. The first reflecting layer 211 can also be a dielectric reflecting layer. The high-refractive material is preferably aluminum oxide, hafnium oxide, scandium oxide, titanium oxide, etc., and the low-refractive material is preferably magnesium fluoride, calcium fluoride, lithium fluoride, silicon oxide, etc. In consideration of the uniformity of the coating film and the processing difficulty, the reflecting surface 21 is preferably an inclined surface, and can also be an arc surface. In order to achieve the effect of near-mirror reflection, the roughness of the reflecting surface 21 should be less than 1 μm, and the smaller the better.

[0037] The base body of the reflecting cup 2 can be metal, crystal, glass, ceramic and organic material. The metal can be commonly used metal such as aluminum, copper, iron, etc., the crystal can be quartz, sapphire, calcium fluoride, magnesium fluoride, etc., the glass can be aluminosilicate glass, borosilicate glass, fluoride glass, etc., the ceramic can be aluminum oxynitride transparent ceramic, aluminum nitride, aluminum oxide ceramic, etc., and the organic material is not a preferred material, but can be used in low-cost solutions of small and medium power. In order to realize the low-cost mass production of the reflecting cup, molding, die casting, molding and other processes can be used, and higher flatness can be realized by combining polishing process.

[0038] In order to ensure the relative position of the reflecting cup 2 and the LED chip 1, the size, shape and position of the reflecting cup are corresponding to the angle distribution of the light intensity of the chip, so as to achieve the best light extraction effect. The present application precisely positions the reflecting cup 2. As shown in Figure 2 a positioning dam 8 is arranged on the upper surface of the substrate 4, and the bottom surface of the reflecting cup 2 has a positioning notch 22 matched with the positioning dam 8, so as to realize the precise positioning of the reflecting cup 2 through the cooperation of the positioning dam 8 and the positioning notch 22.

[0039] As shown in Figure 5 the positioning notch 22 has an inner top surface 221 gradually rising from inside to outside, that is, the inner top surface 221 is in the form of an inclined surface, which facilitates the outward discharge of the glue when the glue is pasted on the positioning dam 8, so as to avoid that too much glue lifts up the reflecting cup 2. In addition, the inclined inner top surface 221 can also increase the contact area between the glue and the reflecting cup 2, and improve the adhesion.

[0040] As shown in Figure 2 , by introducing the reflective cup 2, the originally laterally emitted and easily absorbed light is reflected by the reflective cup 2 and changes direction to be incident to the lens 32 at a very small angle, effectively limiting Fresnel reflection, so that the light can be effectively extracted, thereby improving the light extraction efficiency.

[0041] The luminous distribution of the prior art deep ultraviolet LED chip is shown in Figure 7 , which is the distribution of a small-size deep ultraviolet LED chip, and its light emission characteristics are different from those of a conventional blue light LED, which has the strongest light emission at 0° angle (and the included angle A with the vertical direction), but has the maximum light emission intensity at about 35°. The light at this angle is incident to the lens surface to produce about 5% reflection, and the light at a larger angle is more easily reflected, reaching 10% at 60° (75% of the maximum light emission intensity). After the reflective cup is added, the light at a large angle can be reflected, and after changing direction, it is incident to the lens surface at a very small angle, thereby suppressing the absorption of deep ultraviolet light by the support and light window, and improving the light extraction efficiency. In this case, when the reflective surface 21 is a slope, the preferred inclination angle C (as shown in Figure 2 ) of the reflective surface 21 is in the range of 25°-55°.

[0042] For a large-size deep ultraviolet LED chip, as shown in Figure 8 , its light emission distribution is different, and as the chip size increases, the forward (vertical direction) light emission is significantly enhanced, and the lateral light emission is reduced, resulting in an increase in the proportion of light that needs to be reflected by the lens. The light emission intensity is maximum at about 15°. In this case, the preferred inclination angle range of the reflective surface 21 is reduced. Therefore, the inclination angle range of the reflective surface 21 should be designed according to the specific situation to achieve the best light extraction effect.

[0043] As shown in Figure 2 , in embodiment one, in order to facilitate the positioning of the dam 8 and the fixing of the reflective cup 2, a support layer 9 is provided on the upper surface of the substrate 4, the positioning dam 8 is integrally provided on the support layer 9, and the bottom surface of the reflective cup 2 is fixed on the positioning dam 8 by adhesion.

[0044] As shown in Figure 3 , embodiment two is different from the above-mentioned embodiment one in that the support layer 9 is cancelled in this embodiment, the electrode pad 5 extends outward, the positioning dam 8 is integrally provided on the electrode pad 5, the bottom surface of the reflective cup 2 is fixed on the positioning dam 8 by adhesion, and the reflective cup 2 in this embodiment must be insulated, and is not suitable for a reflective cup 2 made of conductive material.

[0045] As shown in Figure 4The embodiment three shown is different from the embodiment one above in that the support layer 9 is cancelled, the positioning dam 8 is directly arranged on the upper surface of the substrate 4, and the bottom surface of the reflective cup 2 is directly fixed on the positioning dam 8 by adhesion.

[0046] Preferably, the height of the positioning dam 8 is consistent with the height of the electrode pad 5 and the welding layer 7, and the positioning dam 8 is formed by plating a metal layer on the surface of the substrate 4 and etching the channel by an etching process, or a barrier layer of the channel is first made and then etched, which simplifies the manufacturing process.

[0047] Considering the problem that the machining of the acute angle at the bottom of the reflective surface of the reflective cup 2 is difficult, the structure of the reflective cup 2 is optimized. Figure 4 As shown, the lower end of the reflective surface 21 on the reflective cup 2 has a vertical step 23, the height h1 of the step is not higher than the height h2 of the electrode pad 5, and preferably, the height h1 of the step is greater than 50 μm and less than 150 μm, facilitating the machining and manufacturing.

[0048] In order to further improve the light reflection efficiency, as shown, a second reflective layer 51 (high reflection plating layer) is coated on the surface of the electrode pad 5, the reflectivity of which is not less than 80%, and the positions of the chip electrode and the Zener diode electrode are not coated, so as to ensure the reliability of the electrode connection. Figure 6

[0049] As shown, the light window 3 includes an annular enclosure 31 and a lens 32 arranged on the top of the enclosure 31. A solder ring 33 is arranged between the upper end of the enclosure 31 and the periphery of the lens 32, for fixing the lens 32 on the enclosure 31. In order to improve the transmittance of the deep ultraviolet light, the front and back surfaces of the lens 32 are both provided with an anti-reflection film. Figure 2 The enclosure 31 is preferably a metal tube, and preferably a Kovar alloy with low thermal conductivity, which is matched with the thermal expansion coefficients of the ceramic support and the lens as much as possible, so as to improve the reliability of the packaging. The lens 32 can be quartz, sapphire, CaF2, MgF2, fluoride glass, transparent ceramic, etc. with high light transmittance; and the solder ring 33 can be a low-temperature glass sealing material such as bismuth-based glass, phosphate glass, borate glass, etc.

[0050] It is worth noting that the thin reflective cup used in the prior art is difficult to machine at a small scale (mainly because it is difficult to improve the flatness), and it is also difficult to package. The LED light source with the inorganic packaging structure of the reflective cup of the utility model is easy to machine and package, and is easier to mass-produce.

[0051]

[0052] ​​The above merely is the preferred embodiment of the present application, and it should be pointed out that, for the ordinary skilled in the art, without departing from the creative concept of the present application, a number of improvements and refinements can be made, and these all belong to the protection scope of the present application.

Claims

1. A high efficiency deep ultraviolet LED light source characterized by: The application relates to a LED lamp, which comprises a support, an LED chip (1), a reflecting cup (2) and a light window (3) covering the LED chip (1) and the reflecting cup (2), the support comprises a substrate (4), an electrode pad (5) arranged on the upper surface of the substrate (4), a support pad (6) arranged on the lower surface of the substrate (4) and electrically connected with the electrode pad (5), and a welding layer (7) arranged on the periphery of the electrode pad (5), the LED chip (1) is welded on the electrode pad (5), the reflecting cup (2) is annular and surrounds the periphery of the LED chip (1), the inner side of the reflecting cup (2) is provided with a reflecting surface (21) gradually rising from the inside to the outside, the upper surface of the substrate (4) is further provided with a positioning dam (8), and the bottom surface of the reflecting cup (2) is provided with a positioning notch (22) matched with the positioning dam (8).

2. The high efficiency deep UV LED light source of claim 1, wherein: The reflecting surface (21) and the top surface of the reflecting cup (2) are coated with a first reflecting layer (211) with a reflectivity not lower than 80%.

3. The high efficiency deep UV LED light source of claim 1, wherein: The reflecting surface (21) is an inclined surface or an arc surface; when the reflecting surface (21) is an inclined surface, the inclination angle C ranges from 25 DEG to 55 DEG.

4. The high efficiency deep UV LED light source of claim 1, wherein: The upper surface of the substrate (4) is provided with a supporting layer (9), the positioning dam (8) is integrally arranged on the supporting layer (9), and the bottom surface of the reflecting cup (2) is fixed on the positioning dam (8) through adhesion.

5. The high efficiency deep UV LED light source of claim 1, wherein: The electrode pad (5) extends outward, the positioning dam (8) is integrally arranged on the electrode pad (5), the bottom surface of the reflecting cup (2) is fixed on the positioning dam (8) through adhesion, and the reflecting cup (2) is insulated.

6. The high efficiency deep UV LED light source of claim 1, wherein: The positioning dam (8) is directly arranged on the upper surface of the substrate (4), and the bottom surface of the reflecting cup (2) is fixed on the positioning dam (8) through adhesion; the height of the positioning dam (8) is consistent with the height of the electrode pad (5) and the welding layer (7).

7. The high efficiency deep UV LED light source of claim 1, wherein: The positioning notch (22) has an inner top surface (221) gradually rising from the inside to the outside.

8. The high efficiency deep UV LED light source of claim 1, wherein: The lower end of the reflecting surface (21) on the reflecting cup (2) has a vertical step (23), and the height h1 of the step is not higher than the height h2 of the electrode pad (5).

9. The high efficiency deep UV LED light source of claim 1, wherein: The surface of the electrode pad (5) is coated with a second reflecting layer (51) with a reflectivity not lower than 80%, and the positions of the chip electrode and the Zener electrode are not coated.

10. The high efficiency deep UV LED light source of claim 1, wherein: The light window (3) comprises an annular enclosure (31) and a lens (32) arranged on the top of the enclosure (31), a solder ring (33) is arranged between the upper end of the enclosure (31) and the periphery of the lens (32), and the front and back surfaces of the lens (32) are both provided with an anti-reflection film.

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