White light COB light source and preparation method thereof

Abstract

The invention discloses a white light COB light source and a preparation method, and relates to the technical field of LED illumination, and the preparation method specifically comprises the following steps: fixing a blue light flip chip above a PCB through solder paste, fixing a fluorescent diaphragm above the chip, dripping a layer of glue above the chip and the fluorescent diaphragm, and curing to obtain the white light COB light source. The fluorescent membrane can be a single-layer fluorescent membrane or a double-layer fluorescent membrane, is suitable for different fields, has good optical performance, can replace a QD membrane, and reduces the cost.

Description

Technical Field

[0001] The present invention relates to the technical field of LED lighting, and in particular to a white light COB light source and a preparation method thereof. Background Art

[0002] LED lamp, or light-emitting diode lamp, is a commonly used light-emitting semiconductor device. Generally, a chip of electroluminescent semiconductor material is solidified onto a bracket, and then the chip and circuit board are connected by wires, and finally sealed with epoxy resin. It has the advantages of high efficiency, energy saving, and green environmental protection, so it has been widely used in the field of lighting.

[0003] However, LED lamps have a relatively low illumination brightness and are not suitable for large-area lighting. They also have poor heat dissipation performance and are prone to aging, which can easily lead to light decay and reduced lifespan. Therefore, with the continuous development of LED technology, COB (Chip On Board) light sources have gradually emerged as a new type of LED packaging technology. COB light sources directly package multiple LED chips on a metal substrate to form an integrated light-emitting surface. This packaging method not only improves the luminous efficiency of the light source, but also simplifies the production process. It is widely used in places that require large-area lighting, such as shopping mall lighting and stage lighting. At the same time, in order to meet the light sources that require high color reproduction for projectors, televisions, etc., the existing technology introduces QD films (quantum dot films). The structure from bottom to top is generally PCB, blue light flip chip, glue, and QD film, which can significantly enhance the color performance of the display screen, making the colors more vivid, rich and realistic, achieving a wider color gamut coverage, and closer to the effect of natural light. In the QD film, quantum dots are activated by LED backlight sources. When the blue light emitted by the blue LED lamp passes through the quantum dot film, part of the blue light is converted into green and red light by the quantum dots. The unconverted blue light and the green and red light emitted by the quantum dots together form white light, which becomes the light source of the LCD screen. Due to the size effect of quantum dots, the half-peak width of the red, green and blue colors of its spectrum is very narrow, and the half-peak width of the R, G and B colors emitted after the filter is also very narrow, and the monochrome color purity of the display is very high. However, the production process of QD film is relatively complicated and the cost is high, which cannot meet the needs of the majority.

[0004] In summary, in order to solve the above problems, it is of great significance to find a method for preparing a white light COB light source with simple process, low cost, high brightness and wide color gamut. Summary of the invention

[0005] The object of the present invention is to provide a white light COB light source and a preparation method thereof to solve the problems raised in the prior art.

[0006] To achieve the above object, the present invention provides the following technical solutions:

[0007] A method for preparing a white light COB light source, characterized in that it comprises the following steps:

[0008] Fix the blue light flip chip on the PCB board with solder paste, fix the fluorescent film on the chip, drip a layer of glue on the chip and the fluorescent film, and solidify it to obtain a white light COB light source.

[0009] Preferably, the fluorescent film includes one of a single-layer fluorescent film and a double-layer fluorescent film.

[0010] Preferably, the preparation method of the single-layer fluorescent film comprises the following steps: mixing glue, green powder, red powder, silicone light diffuser, and gas-phase silica anti-precipitation agent uniformly to obtain a mixture, and using a molding process to obtain a single-layer fluorescent film.

[0011] Among the raw materials of the single-layer fluorescent film, the mass ratio of glue, green powder, red powder, silicone light diffuser, and fumed silica anti-precipitation agent is 100:10-15:40-60:0.5-2.5:0.5-1.5.

[0012] Preferably, the double-layer fluorescent film is obtained by stacking a green fluorescent film and a red fluorescent film; wherein the green fluorescent film in the double-layer fluorescent film is in contact with the blue light flip chip.

[0013] Preferably, the preparation method of the double-layer fluorescent film comprises the following steps:

[0014] (1) Weighing glue, green powder, silicone light diffuser, and fumed silica anti-precipitation agent as raw materials, stirring and mixing them evenly, and using a molding process to obtain a green fluorescent film;

[0015] (2) Weigh glue, red powder, silicone light diffuser, and fumed silica anti-precipitation agent as raw materials, stir and mix them evenly, and use a molding process to obtain a red fluorescent film.

[0016] Among them, among the raw materials of the green fluorescent diaphragm, the mass ratio of glue, green powder, silicone light diffuser, and fumed silica anti-precipitation agent is 100:10-15:0.5-2.5:0.5-1.5; among the raw materials of the red fluorescent diaphragm, the mass ratio of glue, red powder, silicone light diffuser, and fumed silica anti-precipitation agent is 100:40-60:0.5-2.5:0.5-1.5.

[0017] Preferably, the molding process includes the following steps: the mixture is placed in a vacuum degassing machine for degassing, added into a mold for compression molding, and taken out for baking and curing; the compression molding parameters are: pressure of 10-12MPa, temperature of 60-70°C, and time of 5-10min; the baking and curing parameters are: baking temperature of 80-120°C, and time of 0.5-1h. Preferably, the thickness of the fluorescent film is 80-150μm.

[0018] Among them, in the double-layer fluorescent film, the thickness ratio of the green fluorescent film to the red fluorescent film is 1:4.

[0019] Preferably, the glue is silica gel; the green powder is nitride green powder; and the red powder is KSF red powder.

[0020] Compared with the prior art, the present invention has the following beneficial effects:

[0021] (1) The present invention designs a new type of white light COB structure. Starting from the upper side of the PCB board, the design structure is equipped with a blue light flip chip, a fluorescent film, and glue. Compared with the traditional white light COB structure, the present invention replaces the QD film with a fluorescent film. The fluorescent film is prepared by a molding process, which is simple in process and low in cost. The fluorescent film can effectively absorb and convert the blue light emitted by the LED chip to produce white light with high light efficiency. At the same time, because the process adopts hot pressing after mixing the fluorescent powder and silica gel, the prepared fluorescent film material is relatively tightly combined internally, and a vacuum degassing treatment is also performed, which helps to reduce the gaps and defects between the interfaces, so that the light efficiency is further improved. At the same time, the flexibility and elasticity of silica gel also give the fluorescent film impact and shock resistance, which helps to reduce possible damage caused by accidental impact.

[0022] (2) The present invention provides two methods for preparing white light COBs, which can meet the needs of different scenarios. The present invention mixes green phosphor, red phosphor and silica gel to prepare a single-layer fluorescent film, which is then fixed on a blue light flip chip to obtain a white light COB with a single-layer fluorescent film. The fluorescent film made of such mixed phosphors can form a more uniform color light mixing effect when emitting light, thereby improving the uniformity of light output. This helps to reduce the problems of light spots and uneven brightness and improve lighting efficiency. Compared with double-layer fluorescent diaphragms, the integrated preparation method reduces the steps and equipment required for layered fixation, and the cost can be further reduced. If the color temperature of white light needs to be adjusted, it is only necessary to adjust the mixing ratio of green fluorescent powder and red fluorescent powder. However, it is not convenient to accurately control the required color temperature, and formula development is required. Such a structure is suitable for scenes that require large-scale mass production, unified specifications, and low cost, such as street lights. The present invention also makes green fluorescent powder and red fluorescent powder into fluorescent diaphragms respectively, fixes the green fluorescent diaphragm on one side close to the blue light flip chip, and fixes the red fluorescent diaphragm on the other side of the green fluorescent diaphragm, thereby obtaining a white light COB with a double-layer fluorescent diaphragm. Compared with a single layer, such a double-layer fluorescent film structure can achieve precise color temperature control. It only needs to control the thickness of the fluorescent film, which makes it easier to individually control and adjust the ratio of green light and red light to accurately achieve the required spectral characteristics to meet the needs of different application scenarios. At the same time, the double-layer structure helps to reduce reabsorption, thereby improving light efficiency and brightness. Such a structure is suitable for scenes that require a higher color gamut index and color accuracy, such as high-end lighting, display equipment, etc., and can also replace QD films.

[0023] (3) The double-layer structure adopted by the present invention is that the blue light of the blue light flip chip first passes through the green fluorescent film and then passes through the red fluorescent film. This is because the red fluorescent film has a strong absorption capacity for blue light. If the red fluorescent film is close to the side of the blue light flip chip, most of the blue light will be absorbed by the red light, resulting in a decrease in the blue light used to excite the green fluorescent film, thereby reducing the brightness, light effect and color fidelity; while in the structure of the present invention, the blue light first passes through the green fluorescent film to emit green light, and then a part of the green light and the blue light together excite the red fluorescent film, thereby emitting red light, and the remaining light is emitted together with the red light to obtain white light. Another reason for this design is that the quantum efficiency of the red fluorescent film is lower than that of the green fluorescent film, that is, under the same excitation light energy, the red light will be lower than the green light, and such a structure in which part of the green light and the blue light jointly excite the red fluorescent film can improve the luminous efficiency, thereby improving the brightness and light effect, and can improve the color gamut index, thereby achieving an effect close to that of the QD film.

[0024] (4) The present invention introduces an organosilicon light diffuser in the process of preparing the fluorescent film, which can increase the reflection and refraction of light inside the film, so that the light is more evenly distributed in the film, while allowing more light to pass through the fluorescent substance and then be converted into fluorescence, thereby improving the color uniformity of the light and also improving the luminous efficiency. The present invention also introduces a gas-phase silica anti-precipitation agent, which can change the rheological properties of the system and make it thixotropic, thereby effectively preventing the sedimentation of the fluorescent substance during the preparation and storage process, improving stability, and indirectly improving the production efficiency and the yield rate of the light source. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 This is the production structure diagram of a single-layer fluorescent film COB light source;

[0026] Figure 2 This is the production structure diagram of the double-layer fluorescent film COB light source;

[0027] Figure 3 This is the front view of the COB light source. DETAILED DESCRIPTION

[0028] Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making any creative work shall fall within the scope of protection of the present invention.

[0029] It should be noted that there is no special restriction on the purchasing manufacturers of all the raw materials involved in the present invention, and exemplarily include: blue light flip chip: 3535 / 4040 / 4343 / 4848 / 5252, provided by Jucan Optoelectronics Technology Co., Ltd.; glue: silica gel, CL1000, provided by Dow Corning; green powder: nitride green powder, BG-601 series, D50, 0.3~0.7μm, provided by Mitsubishi Chemical Corporation of Japan; red powder: KSF red powder, LD-3 / F2, D50: 30~35μm, provided by Jiangsu Borui Optoelectronics Co., Ltd.; silicone light diffuser: KMP-590, provided by Suzhou Bingsheng New Materials Technology Co., Ltd.; fumed silica anti-precipitation agent: QS102, provided by Borida (Dongguan) New Materials Co., Ltd.

[0030] In the following examples, parts are by mass, and raw materials are all commercially available.

[0031] The thickness of the fluorescent film in the following embodiments is 100 μm, and the thickness of the green fluorescent film and the red fluorescent film in the double-layer structure are 20 μm and 80 μm respectively.

[0032] Example 1: Step 1: Preparation of single-layer fluorescent film white light COB:

[0033] S1: Preparation of a single-layer fluorescent film: (1) Weigh glue, green powder, red powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:12.5:50:1.5:1, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 65°C for 10 min at 10 MPa. After taking it out, bake it at 150°C for 1 h to obtain a single-layer fluorescent film;

[0034] S2: Preparation of single-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the fluorescent film on the chip, drip a layer of glue on the chip and the fluorescent film, and solidify it to obtain a single-layer fluorescent film white light COB light source;

[0035] Step 2: Preparation of double-layer fluorescent film white light COB:

[0036] S1: Preparation of green fluorescent film: (1) Weigh glue, green powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:12.5:1.5:1, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 65°C for 10 min at 10 MPa. After taking it out, bake it at 150°C for 1 h to obtain a green fluorescent film;

[0037] S2: Preparation of red fluorescent film: (1) Weigh glue, red powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:50:1.5:1, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 65°C for 10 min at 10 MPa. After taking it out, bake it at 150°C for 1 h to obtain a red fluorescent film;

[0038] S3: Preparation of double-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the green fluorescent film on the chip, fix the red fluorescent film on the green fluorescent film, drop a layer of glue on the chip and the fluorescent film, and solidify it to obtain a double-layer fluorescent film white light COB light source.

[0039] Example 2: Step 1: Preparation of single-layer fluorescent film white light COB:

[0040] S1: Preparation of a single-layer fluorescent film: (1) Weigh glue, green powder, red powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:10:40:0.5:0.5, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 60°C for 5 min at 10 MPa. After taking it out, bake it at 140°C for 0.5 h to obtain a single-layer fluorescent film;

[0041] S2: Preparation of single-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the fluorescent film on the chip, drip a layer of glue on the chip and the fluorescent film, and solidify it to obtain a single-layer fluorescent film white light COB light source;

[0042] Step 2: Preparation of double-layer fluorescent film white light COB:

[0043] S1: Preparation of green fluorescent film: (1) Weigh glue, green powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:10:0.5:0.5, mix them evenly, transfer them to a vacuum degassing machine for degassing treatment, and obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, hot press it at 60°C with 10 MPa for 5 min, take it out and bake it at 140°C for 0.5 h to obtain a green fluorescent film;

[0044] S2: Preparation of red fluorescent film: (1) Weigh glue, red powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:40:0.5:0.5, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 60°C for 5 min at 10 MPa. After taking it out, bake it at 140°C for 0.5 h to obtain a red fluorescent film;

[0045] S3: Preparation of double-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the green fluorescent film on the chip, fix the red fluorescent film on the green fluorescent film, drop a layer of glue on the chip and the fluorescent film, and solidify it to obtain a double-layer fluorescent film white light COB light source.

[0046] Example 3: Step 1: Preparation of single-layer fluorescent film white light COB:

[0047] S1: Preparation of a single-layer fluorescent film: (1) Weigh glue, green powder, red powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:15:60:2.5:1.5, mix them evenly, transfer them to a vacuum degassing machine for degassing treatment, and obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, hot press it at 70°C at 15 MPa for 10 min, take it out and bake it at 160°C for 1 h to obtain a single-layer fluorescent film;

[0048] S2: Preparation of single-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the fluorescent film on the chip, drip a layer of glue on the chip and the fluorescent film, and solidify it to obtain a single-layer fluorescent film white light COB light source;

[0049] Step 2: Preparation of double-layer fluorescent film white light COB:

[0050] S1: Preparation of green fluorescent film: (1) Weigh glue, green powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:15:2.5:1.5, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 70°C for 10 min at 15 MPa. After taking it out, bake it at 160°C for 1 h to obtain a fluorescent film crude product; (3) De-mold the fluorescent film crude product, trim it, and inspect it to obtain a green fluorescent film;

[0051] S2: Preparation of red fluorescent film: (1) Weigh glue, red powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:60:2.5:1.5, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 70°C for 10 min at 15 MPa. After taking it out, bake it at 160°C for 1 h to obtain a red fluorescent film;

[0052] S3: Preparation of double-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the green fluorescent film on the chip, fix the red fluorescent film on the green fluorescent film, drop a layer of glue on the chip and the fluorescent film, and solidify it to obtain a double-layer fluorescent film white light COB light source.

[0053] Comparative Example 1: A white light COB light source is prepared using a PCB board, a blue light flip chip, glue, and a QD film, as follows:

[0054] The blue light flip chip is fixed on the PCB board through solder paste, the QD film (thickness is 100μm) is fixed on the chip, and a layer of glue is dripped on the chip and QD film, and cured to obtain a white light COB light source.

[0055] Comparative Example 2: Based on Example 1, the thickness of the fluorescent film is increased to 200 μm, and the other processes remain unchanged, as follows:

[0056] The thickness of the fluorescent film is 200 μm, and the thickness of the green fluorescent film and the red fluorescent film in the double-layer structure are 40 μm and 160 μm respectively.

[0057] Step 1: Preparation of single-layer fluorescent film white light COB:

[0058] S1: Preparation of a single-layer fluorescent film: (1) Weigh glue, green powder, red powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:12.5:50:1.5:1, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 65°C for 10 min at 10 MPa. After taking it out, bake it at 150°C for 1 h to obtain a single-layer fluorescent film;

[0059] S2: Preparation of single-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the fluorescent film on the chip, drip a layer of glue on the chip and the fluorescent film, and solidify it to obtain a single-layer fluorescent film white light COB light source;

[0060] Step 2: Preparation of double-layer fluorescent film white light COB:

[0061] S1: Preparation of green fluorescent film: (1) Weigh glue, green powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:12.5:1.5:1, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 65°C for 10 min at 10 MPa. After taking it out, bake it at 150°C for 1 h to obtain a green fluorescent film;

[0062] S2: Preparation of red fluorescent film: (1) Weigh glue, red powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:50:1.5:1, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 65°C for 10 min at 10 MPa. After taking it out, bake it at 150°C for 1 h to obtain a red fluorescent film;

[0063] S3: Preparation of double-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the green fluorescent film on the chip, fix the red fluorescent film on the green fluorescent film, drop a layer of glue on the chip and the fluorescent film, and solidify it to obtain a double-layer fluorescent film white light COB light source.

[0064] Comparative Example 3: Based on Example 1, during the preparation of the fluorescent film, no silicone light diffusing agent was added, as follows:

[0065] Step 1: Preparation of single-layer fluorescent film white light COB:

[0066] S1: Preparation of a single-layer fluorescent film: (1) Weigh glue, green powder, red powder, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:12.5:50:1, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 65°C for 10 min at 10 MPa. After taking it out, bake it at 150°C for 1 h to obtain a single-layer fluorescent film;

[0067] S2: Preparation of single-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the fluorescent film on the chip, drip a layer of glue on the chip and the fluorescent film, and solidify it to obtain a single-layer fluorescent film white light COB light source;

[0068] Step 2: Preparation of double-layer fluorescent film white light COB:

[0069] S1: Preparation of green fluorescent film: (1) Weigh glue, green powder and fumed silica anti-precipitation agent respectively in a mass ratio of 100:12.5:1, mix them evenly, transfer them to a vacuum degassing machine for degassing treatment, and obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, hot press it at 65°C at 10 MPa for 10 min, take it out and bake it at 150°C for 1 h to obtain a green fluorescent film;

[0070] S2: Preparation of red fluorescent film: (1) Weigh glue, red powder, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:50:1, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 65°C for 10 min at 10 MPa. After taking it out, bake it at 150°C for 1 h to obtain a red fluorescent film;

[0071] S3: Preparation of double-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the green fluorescent film on the chip, fix the red fluorescent film on the green fluorescent film, drop a layer of glue on the chip and the fluorescent film, and solidify it to obtain a double-layer fluorescent film white light COB light source.

[0072] Comparative Example 4: Based on Example 1, during the preparation of a double-layer fluorescent film white light COB light source, the order of the green fluorescent film and the red fluorescent film was exchanged, and the other processes remained unchanged, as follows:

[0073] Step 1: Preparation of single-layer fluorescent film white light COB:

[0074] S1: Preparation of green fluorescent film: (1) Weigh glue, green powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:12.5:1.5:1, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 65°C for 10 min at 10 MPa. After taking it out, bake it at 150°C for 1 h to obtain a green fluorescent film;

[0075] S2: Preparation of red fluorescent film: (1) Weigh glue, red powder, silicone light diffuser, and fumed silica anti-precipitation agent respectively in a mass ratio of 100:50:1.5:1, mix them evenly, and transfer them to a vacuum degassing machine for degassing to obtain a degassing mixture; (2) Transfer the degassing mixture to a mold, spread it evenly, and hot press it at 65°C for 10 min at 10 MPa. After taking it out, bake it at 150°C for 1 h to obtain a red fluorescent film;

[0076] S3: Preparation of double-layer fluorescent film white light COB: fix the blue light flip chip on the PCB board through solder paste, fix the red fluorescent film on the chip, fix the green fluorescent film on the red fluorescent film, drop a layer of glue on the chip and the fluorescent film, and solidify it to obtain a double-layer fluorescent film white light COB light source.

[0077] Performance test: According to GB / T 39394-2020 "Test methods for LED lamps, LED lamps and LED modules" at room temperature of 25°C, the light performance of Example 1 and Comparative Example 1 was tested using a PMS-80 visible light spectrum analysis system, and the experimental data are shown in Table 1; the brightness of each embodiment was measured using a brightness meter, and the experimental data are shown in Table 2;

[0078] Table 1

[0079]

[0080] Table 2

[0081]

[0082] Conclusion: (1) It can be seen from Table 1 that compared with the white light COB light source prepared by the present invention, the data of the white light COB light source prepared by the double-layer fluorescent film is closer to that prepared by the QD film, and it can replace the QO film. The single-layer structure may have a reabsorption phenomenon, which makes the performance slightly weaker; (2) It can be seen from Table 2 that in Comparative Example 2, the thickness of the fluorescent film is increased, which increases the propagation path of light in the fluorescent film, thereby causing a decrease in the luminous brightness; in the process of preparing the fluorescent film in Comparative Example 3, no silicone light diffuser is added, which reduces the reflection and refraction inside the film, reduces the amount of light passing through the fluorescent material, and causes a decrease in brightness; Comparative Example 4 exchanges the order of the green fluorescent film and the red fluorescent film, so that most of the blue light emitted by the blue flip chip is absorbed by the red fluorescent film, which reduces the overall brightness.

[0083] In summary, the PCB board, blue light flip chip, fluorescent film, and glue structure provided by the present invention can fully stimulate the luminous characteristics of the fluorescent film, improve the brightness, have good luminous efficiency and color gamut index, and the fluorescent film has good uniformity and high yield rate, and can be used as a substitute for QD film to save costs.

[0084] Finally, it should be noted that the above description is only a preferred embodiment of the present invention and is not intended to limit the present invention. Although the present invention has been described in detail with reference to the aforementioned embodiments, those skilled in the art can still modify the technical solutions described in the aforementioned embodiments or replace some of the technical features therein by equivalents. Any modification, equivalent replacement, improvement, etc. made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims

1. A method for preparing a white light COB light source, characterized in that: The following steps are involved: Fix the blue light flip chip on the PCB board with solder paste, fix the fluorescent film on the chip, drip a layer of glue on the chip and the fluorescent film, and solidify it to obtain a white light COB light source.

2. The method for preparing a white light COB light source according to claim 1, characterized in that: The fluorescent film includes one of a single-layer fluorescent film and a double-layer fluorescent film.

3. The method for preparing a white light COB light source according to claim 2, characterized in that: The preparation method of the single-layer fluorescent film comprises the following steps: mixing glue, green powder, red powder, silicone light diffuser, and fumed silica anti-precipitation agent uniformly to obtain a mixture, and using a molding process to obtain the single-layer fluorescent film.

4. The method for preparing a white light COB light source according to claim 3, characterized in that: Among the raw materials of the single-layer fluorescent film, the mass ratio of glue, green powder, red powder, silicone light diffuser, and gas-phase silica anti-precipitation agent is 100:10-15:40-60:0.5-2.5:0.5-1.

5.

5. The method for preparing a white light COB light source according to claim 2, characterized in that: The double-layer fluorescent film is obtained by stacking a green fluorescent film and a red fluorescent film; wherein the green fluorescent film in the double-layer fluorescent film is in contact with the blue light flip chip.

6. The method for preparing a white light COB light source according to claim 2, characterized in that: The preparation method of the double-layer fluorescent film comprises the following steps: (1) Weighing glue, green powder, silicone light diffuser, and fumed silica anti-precipitation agent as raw materials, stirring and mixing them evenly, and using a molding process to obtain a green fluorescent film; (2) Weigh glue, red powder, silicone light diffuser, and fumed silica anti-precipitation agent as raw materials, stir and mix them evenly, and use a molding process to obtain a red fluorescent film.

7. The method for preparing a white light COB light source according to claim 6, characterized in that: Among the raw materials of the green fluorescent diaphragm, the mass ratio of glue, green powder, silicone light diffuser, and fumed silica anti-precipitation agent is 100:10-15:0.5-2.5:0.5-1.5; among the raw materials of the red fluorescent diaphragm, the mass ratio of glue, red powder, silicone light diffuser, and fumed silica anti-precipitation agent is 100:40-60:0.5-2.5:0.5-1.

5.

8. A method for preparing a white light COB light source according to any one of claims 3 and 6, characterized in that: The molding process The method comprises the following steps: placing the mixed material into a vacuum degassing machine for degassing treatment, adding the mixed material into a mold for compression molding, and taking the mixed material out for baking and curing; the compression molding parameters are: pressure of 10-12MPa, temperature of 60-70°C, and time of 5-10min; and the baking and curing parameters are: baking temperature of 140-160°C, and time of 0.5-1h.

9. The method for preparing a white light COB light source according to claim 1, characterized in that: The thickness of the fluorescent film is 80-150 μm. 10 . A white light COB light source prepared by the method for preparing a white light COB light source according to claim 1 .

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