COB Packaging Structure of UVC-LED and Its Manufacturing Method

Abstract

The present invention discloses a COB packaging structure of a UVC-LED and a manufacturing method thereof, which includes a ceramic circuit board, a ceramic dam, a transparent cover plate, a UVC-LED chip, a ceramic insulating plate and a reflective layer plate. The structure design of the COB packaging structure of the UVC-LED provided by the present invention is ingenious and reasonable. The light emitted by the UVC-LED chip is reflected out of the transparent cover plate through the reflective coating of the flared hole, effectively improving the directivity of the light and greatly increasing the light output efficiency of the COB light source. Moreover, the ceramic insulating plate has stable performance compared with insulating glue, avoiding the risk of short circuit caused by aging and having high safety. A metal protective layer is plated at the adhesive joint of the transparent cover plate to prevent the insulating glue from being aged by UVC light irradiation and extend the service life. The manufacturing method of the COB packaging structure of the UVC-LED provided by the present invention has simple process and low cost and is suitable for industrial production.

Description

Technical Field

[0001] The present invention relates to the technical field of LEDs, and particularly relates to a COB packaging structure for UVC-LEDs and a manufacturing method thereof. Background Art

[0002] UVC ultraviolet rays have a short wavelength (200-280nm) and high energy, and can destroy the molecular structures in the cells of microorganisms (such as bacteria, viruses and other pathogens), such as DNA and RNA, etc., causing them to die immediately or be unable to reproduce offspring, achieving an efficient and rapid broad-spectrum sterilization effect. Traditional ultraviolet lamps are mainly low-pressure mercury lamps, which generate ultraviolet rays with a wavelength of 253nm by the excitation of mercury atoms, but they have the disadvantages of mercury toxicity, slow response time and high energy consumption. The UVC-LED solid-state light source has the advantages of environmental protection, adjustable power, low energy consumption, etc., and is currently the only solid-state light source solution to replace the mercury-excited ultraviolet light source.

[0003] Aiming at the disadvantage of the low power of a single UVC-LED light source, the COB (Chip on board) packaging technology is adopted to integrate multiple UVC-LED chips on the same substrate, which can realize an integrated light source module with a high power density, thereby improving the sterilization and disinfection effect. Since the light emitted by the COB light source towards the substrate direction will be strongly absorbed by the substrate, in order to further improve the light output power density of the COB light source of UVC-LEDs, technicians adopt the method of preparing a mirror structure on the substrate to reflect this part of the light.

[0004] Chinese Patent No. CN110223972A, with the name of "An Inverted COB Light Source with a Mirror Structure and a Preparation Method Thereof", discloses an inverted COB light source with a mirror structure and a preparation method thereof. After curing an insulating transparent glue on the COB substrate with the chips welded, a high-reflection metal layer is plated to improve the reflectivity of the bottom of the COB substrate. However, there is a risk of aging of the insulating transparent glue after the COB light source works for a long time, resulting in a short circuit between the high-reflection metal layer and the substrate circuit.

[0005] Chinese Patent No. CN206076228U, with the name of "A New Structure COB Packaging Structure", discloses a new structure COB packaging structure, in which a plurality of LED chips are fixed on a plate coated with reflective white glue to improve heat dissipation and reduce light decay. However, the LED chips are electrically connected by welding wires between them and between the edge LED chips and the conductive circuit layer, the welding wire cost is high, and there is also a risk of short circuit caused by aging of the reflective white glue. Summary of the Invention

[0006] Aiming at the above deficiencies, one of the purposes of the present invention is to provide a COB packaging structure for UVC-LEDs with a clever and reasonable structure, which effectively improves the light extraction efficiency and is stable and reliable.

[0007] Another purpose of the present invention is to provide a manufacturing method for the COB packaging structure of UVC-LEDs, which has a simple process, low cost, and is suitable for industrial production.

[0008] To achieve the above purposes, the technical solutions provided by the present invention are as follows:

[0009] A COB packaging structure for UVC-LEDs, which includes a ceramic circuit board, a ceramic dam, a transparent cover plate, UVC-LED chips, a ceramic insulating board, and a reflective layer board. A number of UVC-LED chips are distributed on the ceramic circuit board to form a light-emitting area. The ceramic insulating board is arranged on the ceramic circuit board and has an opening for the UVC-LED chips to be exposed. The reflective layer board is arranged on the ceramic insulating board and has a flared hole corresponding to the opening. The surface of the reflective layer board and the hole wall of the flared hole are both provided with a reflective coating. The ceramic dam is arranged on the ceramic circuit board and surrounds the light-emitting area. The transparent cover plate is arranged on the ceramic dam and closes the upper position of the light-emitting area.

[0010] As an improvement of the present invention, the inclination angle of the hole wall of the flared hole is 15°-45°, which has a good reflection effect and improves the light extraction efficiency.

[0011] As an improvement of the present invention, the reflective coating is a high-reflection aluminum layer, molybdenum layer, or magnesium oxide layer with a reflectivity of 70-99% and a thickness of 100-5000 nm, which has a high light reflectivity.

[0012] As an improvement of the present invention, the ceramic dam is fixed on the ceramic circuit board through an insulating adhesive. The transparent cover plate is fixed on the ceramic dam through an insulating adhesive. It is easy to achieve by pasting with an insulating adhesive.

[0013] As an improvement of the present invention, the insulating adhesive is one or several of epoxy resin, silicone resin, or silicone rubber. It has a firm paste, a tight fit, and a long service life.

[0014] As an improvement of the present invention, a metal protective layer is provided between the transparent cover plate and the insulating adhesive. The metal protective layer is a metal film formed by superimposing or combining one or several of titanium, copper, aluminum, or chromium. The thickness of the metal film is 50-400 nm. The metal protective layer is used to prevent the insulating adhesive from aging due to UVC light irradiation and extend the service life.

[0015] As an improvement of the present invention, the substrate of the ceramic circuit board is made of alumina or aluminum nitride material.

[0016] As an improvement of the present invention, the ceramic insulating plate is a plate body made of alumina, zirconia or ZTA ceramic material with a thickness less than 0.15 mm, which is high temperature resistant, stable in property, good in insulation and has a coefficient of thermal expansion matching that of the ceramic circuit board.

[0017] As an improvement of the present invention, the reflective layer plate is a metal plate body made of one or several of silver, aluminum, copper, iron, stainless steel or iron-nickel alloy.

[0018] As an improvement of the present invention, the UVC-LED chip is a deep ultraviolet light-emitting diode chip with a light-emitting wavelength of 200-280 nm.

[0019] As an improvement of the present invention, the ceramic dam is a dam body made of alumina, aluminum nitride or zirconia material, which has high hardness, a coefficient of thermal expansion matching that of the ceramic circuit board and good cooperation stability.

[0020] As an improvement of the present invention, the transparent cover plate is sapphire glass, quartz glass or borosilicate glass. It is scratch-resistant, wear-resistant, high temperature resistant and has high spectral transmittance, with good light transmission effect.

[0021] A manufacturing method of a COB packaging structure of a UVC-LED includes the following steps:

[0022] (1) Weld the UVC-LED chip on the ceramic circuit board;

[0023] (2) Fix the ceramic dam on the ceramic circuit board and enclose all the UVC-LED chips;

[0024] (3) Pre-drill openings corresponding to the positions of the UVC-LED chips on the ceramic insulating plate, fix the ceramic insulating plate on the ceramic circuit board, and make each UVC-LED chip be located at the middle position of its corresponding opening;

[0025] (4) Stick a mask on one surface of the reflective layer plate, perform wet etching to obtain flared holes, tear off the mask, and coat the reflective layer plate by vacuum thermal evaporation, vacuum sputtering coating, electroplating or combined coating methods to form a reflective coating on the surface of the reflective layer plate and the hole walls of the flared holes;

[0026] (5) Press the other surface of the reflective layer plate against the ceramic insulating plate, and make the flared holes on the reflective layer plate correspond exactly to the openings on the ceramic insulating plate, so that the UVC-LED chips passing through the openings can extend into the flared holes; the diameter of the flared hole near the ceramic insulating plate is smaller at one end and gradually increases at the other end;

[0027] (6) A metal protective layer is deposited on the adhesive of the transparent cover plate by means of vacuum thermal evaporation coating, vacuum sputtering coating, electroplating, sintering or combined coating, and then an insulating adhesive is coated on the metal protective layer and fixed on the ceramic dam through this insulating adhesive to encapsulate all UVC-LED chips in a closed space;

[0028] Steps (1)-(3) and (4) are not in a sequential order.

[0029] The beneficial effects of the present invention are as follows: The COB packaging structure of the UVC-LED provided by the present invention has a clever and reasonable structural design. The light emitted by the UVC-LED chips is reflected out of the transparent cover plate through the reflective coating of the flared hole, effectively improving the directivity of the light and greatly increasing the light extraction efficiency of the COB light source; The ceramic insulating plate has stable performance compared with the insulating adhesive, avoiding the risk of short circuit caused by aging; A metal protective layer is deposited on the adhesive of the transparent cover plate to prevent the insulating adhesive from being aged by UVC light irradiation and extend the service life; The manufacturing method of the COB packaging structure of the UVC-LED provided by the present invention has a simple process and low cost, and is suitable for industrial production.

[0030] The present invention will be further described below in conjunction with the drawings and embodiments. Description of the Drawings

[0031] Figure 1 is a schematic cross-sectional structure view of the present invention.

[0032] Figure 2 is a schematic top view structure view of the present invention. Detailed Embodiments

[0033] Embodiment, refer to Figure 1 and Figure 2 A COB packaging structure of a UVC-LED provided in this embodiment includes a ceramic circuit board 1, a ceramic dam 2, a transparent cover plate 3, UVC-LED chips 4, a ceramic insulating plate 5 and a reflective layer plate 6.

[0034] Among them, the ceramic dam 2 is preferably a dam made of alumina, aluminum nitride or zirconia materials, with high hardness and good structural stability. The transparent cover plate 3 is preferably sapphire glass, quartz glass or borosilicate glass, etc. It is scratch-resistant, wear-resistant, high-temperature resistant, and has high spectral transmittance and good light transmission effect.

[0035] The substrate of the ceramic circuit board 1 is preferably aluminum nitride ceramic or alumina ceramic, and a conductive circuit is prepared on it by means of electroplating and wet etching.

[0036] The UVC-LED chip 4 is preferably a deep ultraviolet light-emitting diode chip with a light-emitting wavelength of 200-280 nm. A number of UVC-LED chips 4 are evenly distributed and positioned on the ceramic circuit board 1 and welded to the conductive circuit thereon. The UVC-LED chips 4 can be arranged and distributed on the ceramic circuit board 1 in a matrix or radial manner to form a light-emitting area.

[0037] The ceramic dam 2 is fixed on the ceramic circuit board 1 by an insulating adhesive 7 and encloses the light-emitting area. The insulating adhesive 7 is preferably one or more of epoxy resin, silicone resin or silicone rubber. The ceramic dam 2 is pasted and fixed by the insulating adhesive 7, with firm pasting, close fit and long service life. The height of the ceramic dam 2 is slightly higher than that of the UVC-LED chip 4. In this embodiment, the height of the UVC-LED chip 4 is 0.3 mm and the height of the ceramic dam 2 is 0.55 mm. In other embodiments, the heights of the UVC-LED chip 4 and the ceramic dam 2 can be adjusted accordingly, as long as the height of the ceramic dam 2 is slightly higher than that of the UVC-LED chip 4.

[0038] The ceramic insulating plate 5 is arranged on the ceramic circuit board 1 and has an opening for the UVC-LED chip 4 to be exposed, and the outer contour of the opening is circular. The ceramic insulating plate 5 is preferably a ZTA ceramic plate with a thickness of 0.1 mm. In other embodiments, the ceramic insulating plate 5 can also be a plate body made of alumina or zirconia material with a thickness less than 0.15 mm.

[0039] The reflective layer plate 6 is arranged on the ceramic insulating plate 5. The reflective layer plate 6 is preferably a metal plate body made of one or several of silver, aluminum, copper, iron, stainless steel or iron-nickel alloy. The reflective layer plate 6 has a flared hole 61 corresponding to the opening, and the inclination angle of the hole wall of the flared hole 61 is 15°-45°, with good reflection effect and improved light extraction efficiency. The diameter of the flared hole 61 at the end close to the ceramic insulating plate 5 is smaller, and the other end gradually increases. A reflective coating 62 is provided on the surface of the reflective layer plate 6 and the hole wall of the flared hole 61. The reflective coating 62 is preferably a high-reflection aluminum layer, molybdenum layer or magnesium oxide layer with a reflectivity of 70-99% and a thickness of 100-5000 nm, with high UVC light reflectivity.

[0040] The transparent cover plate 3 is arranged on the ceramic dam 2 and closes the upper position of the light-emitting area. Specifically, the transparent cover plate 3 is pasted and fixed on the ceramic dam 2 by an insulating adhesive 8, and the pasting installation by the insulating adhesive 8 is easy to achieve. The insulating adhesive 8 is preferably one or more of epoxy resin, silicone resin or silicone rubber. The pasting is firm, the fit is close and the service life is long.

[0041] Preferably, a metal protection layer 9 is further provided between the transparent cover plate 3 and the insulating glue 8. The metal protection layer 9 is a metal film formed by one or several of titanium, copper, aluminum or chromium in superposition or combination, and the thickness of the metal film is 50-400 nm. The metal protection layer is used to prevent the insulating glue from aging due to UVC light irradiation and extend the service life.

[0042] A manufacturing method of a COB packaging structure of a UVC-LED includes the following steps:

[0043] (1) Weld the UVC-LED chip 4 to the ceramic circuit board 1;

[0044] (2) Paste and fix the ceramic dam 2 to the ceramic circuit board 1 through the insulating glue 7, and enclose all the UVC-LED chips 4;

[0045] (3) An opening corresponding to the position of the UVC-LED chip 4 is pre-opened on the ceramic insulating plate 5, the ceramic insulating plate 5 is fixed on the ceramic circuit board 1, and the ceramic insulating plate 5 is limited by the ceramic dam 2, so that each UVC-LED chip 4 is respectively located in the middle position of the corresponding opening;

[0046] (4) Paste a mask on one surface of the reflective layer board 6, perform wet etching to obtain a flared hole 61, tear off the mask, and coat the reflective layer board by means of vacuum thermal evaporation, vacuum sputtering coating, electroplating or combined coating, so as to form a reflective coating 62 on the surface of the reflective layer board and the hole wall position of the flared hole 61;

[0047] The steps (1)-(3) and (4) are not in a sequential order, that is, steps (1)-(3) can be completed first, or step (4) can be completed first, and then steps (1)-(3) are executed;

[0048] (5) Press the other surface of the reflective layer board 6 against the ceramic insulating plate 5, and limit the reflective layer board 6 by the ceramic dam 2, so that the flared hole 61 on the reflective layer board 6 is aligned with the opening on the ceramic insulating plate 5 correspondingly, so that the UVC-LED chip 4 passing through the opening can extend into the flared hole 61; the diameter of the flared hole 61 at one end close to the ceramic insulating plate 5 is smaller, and the other end is gradually increasing;

[0049] (6) A metal protection layer 9 is coated at the glue application position of the transparent cover plate 3 by means of vacuum thermal evaporation, vacuum sputtering coating, electroplating, sintering or combined coating, then an insulating glue 8 is coated on the metal protection layer 9, and the ceramic dam 2 is paste-fixed through the insulating glue 8 to cover all the UVC-LED chips 4. During operation, the light emitted by the UVC-LED chip 4 is reflected out of the transparent cover plate 3 through the reflective coating 62 of the flared hole 61, effectively improving the light directivity and having a high UVC light output efficiency.

[0050] Based on the disclosure and teachings of the above specification, those skilled in the art to which the present invention pertains can also make changes and modifications to the above embodiments. Therefore, the present invention is not limited to the specific embodiments disclosed and described above, and some modifications and changes to the present invention should also fall within the scope of protection of the claims of the present invention. In addition, although some specific terms are used in this specification, these terms are only for convenience of description and do not constitute any limitation to the present invention. As described in the above embodiments of the present invention, other structures and methods obtained by adopting the same or similar structures are within the scope of protection of the present invention.

Claims

1. A COB packaging structure of UVC-LED, characterized in that: It includes a ceramic circuit board, a ceramic dam, a transparent cover plate, a UVC-LED chip, a ceramic insulating plate and a reflective layer plate. A plurality of UVC-LED chips are distributed on the ceramic circuit board to form a light-emitting area. The ceramic insulating plate is arranged on the ceramic circuit board and has multiple openings for exposing the UVC-LED chips. Each UVC-LED chip is located in the middle of an opening corresponding to the ceramic circuit board. The reflective layer plate is arranged on the ceramic insulating plate and has an expanded hole corresponding to the opening. The surface of the reflective layer plate and the wall of the expanded hole are both provided with a reflective coating. The ceramic dam is arranged on the ceramic circuit board and encloses the light-emitting area. The transparent cover plate is arranged on the ceramic dam and seals the upper part of the light-emitting area. The transparent cover is fixed on the ceramic dam by insulating glue; A metal protective layer is provided between the transparent cover and the insulating adhesive; The metal protective layer is a metal film formed by stacking or combining one or more of titanium, copper or chromium, and the thickness of the metal film is 50-400 nm.

2. The COB packaging structure of UVC-LED according to claim 1, characterized in that: The inclination angle of the hole wall of the expanded hole is 15° to 45°.

3. The COB packaging structure of UVC-LED according to claim 1, characterized in that: The reflective coating is a highly reflective aluminum layer, molybdenum layer or magnesium oxide layer with a reflectivity of 70-99% and a thickness of 100-5000 nm.

4. The COB packaging structure of UVC-LED according to claim 1, characterized in that: The ceramic dam is fixed to the ceramic circuit board by insulating glue.

5. The COB packaging structure of UVC-LED according to claim 4, characterized in that: The insulating adhesive is one or more of epoxy resin, silicone resin or silicone rubber.

6. The COB packaging structure of UVC-LED according to any one of claims 1 to 5, characterized in that: The substrate of the ceramic circuit board is made of aluminum nitride or aluminum oxide; The ceramic insulating plate is made of alumina, zirconia or ZTA ceramic material with a thickness of less than 0.15 mm; The reflective layer is a metal plate made of one or a mixture of silver, aluminum, copper, iron, stainless steel or iron-nickel alloy; The UVC-LED chip is a deep ultraviolet light emitting diode chip with a light emission wavelength of 200 to 280 nm; The ceramic dam is a dam body made of aluminum oxide, aluminum nitride or zirconium oxide; The transparent cover plate is made of sapphire glass, quartz glass or high-boron glass.

7. A method for manufacturing the COB packaging structure of a UVC-LED according to any one of claims 1 to 6, characterized in that: It includes the following steps: (1) Solder the UVC-LED chip to the ceramic circuit board; (2) Fix the ceramic dam on the ceramic circuit board and surround all UVC-LED chips; (3) Pre-openings corresponding to the positions of the UVC-LED chips are formed on the ceramic insulating plate, and the ceramic insulating plate is fixed to the ceramic circuit board so that each UVC-LED chip is located in the middle of the corresponding opening; (4) attaching a mask to one surface of the reflective layer, performing wet etching to obtain an expanded hole, removing the mask, and coating the reflective layer by vacuum thermal evaporation, vacuum sputtering, electroplating, or a combination of these methods to form a reflective coating on the surface of the reflective layer and the wall of the expanded hole; (5) The other surface of the reflective layer is placed in close contact with the ceramic insulating plate, and the expanded hole on the reflective layer is aligned with the opening on the ceramic insulating plate so that the UVC-LED chip passing through the opening can extend into the expanded hole; wherein the diameter of the expanded hole close to one end of the ceramic insulating plate is smaller and the diameter of the other end is gradually enlarged; (6) A metal protective layer is plated on the adhesive portion of the transparent cover plate by vacuum thermal evaporation, vacuum sputtering coating, electroplating, sintering or a combination of coating methods, and then an insulating adhesive is coated on the metal protective layer, and the insulating adhesive is adhered and fixed to the ceramic dam to encapsulate all UVC-LED chips in a closed space; The steps (1)-(3) and (4) are performed in no particular order.

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