A phosphor-free multi-primary-color LED packaging structure and its packaging method

Abstract

The present invention discloses a phosphor-free multi-primary-color LED packaging structure and its packaging method. The packaging structure includes a packaging substrate, a plurality of LED chips placed at intervals, a die bonding layer, leads, and a composite encapsulation glue structure. There are a plurality of LED chips bonded through the die bonding layer on the packaging substrate. The LED chips are electrically connected to the substrate circuit through the leads. There is a composite encapsulation glue structure on the multi-primary-color LED chips. The composite encapsulation glue structure is composed of a first encapsulation glue layer of pure encapsulation glue and a second encapsulation glue layer doped with micro-nano scattering particles, and the second encapsulation glue layer is located around the first encapsulation glue layer. In this way, it is ensured that most of the light directly exits from the first encapsulation glue layer, and the large-angle light undergoes a scattering effect with the micro-nano particles in the second encapsulation glue layer doped with micro-nano particles, thereby improving the angular uniformity of the light emitted by different LED chips, realizing the mixing of light with a large viewing angle, and at the same time ensuring a high light extraction efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of LED packaging, and particularly relates to a phosphor-free multi-primary-color LED packaging structure and a packaging method thereof. Background Art

[0002] LED (Light Emitting Diodes) is a semiconductor light-emitting device based on the principle of electroluminescence of P-N junctions, which has the advantages of high electro-optical conversion efficiency, long service life, environmental protection, energy saving, small size, etc. It has begun to be widely used in many fields such as backlighting, street lamps, automotive headlights, headlamps and indoor lighting. With the continuous improvement of LED efficiency and the promotion of application products, people's demand for LED lighting has gradually changed from "illuminating" to "illuminating comfortably". Therefore, spatial color uniformity has become one of the important evaluation indicators of LED lighting quality.

[0003] Currently, there are mainly two ways to synthesize white light LEDs. One is to use blue LED chips to excite phosphors to synthesize white light; the other is to synthesize white light through multi-color LED chips (such as blue, cyan, green, yellow and red LED chips). Synthesizing white light by combining blue light chips with yellow phosphors has problems such as excessive blue light, lack of cyan light and insufficient red light in its spectrum. More and more studies have shown that there is a serious problem of blue light leakage in the white light LED light source synthesized by this method over time. Since the proportion of blue light in the spectrum is relatively large, it will have a non-visual biological effect on users, affect melatonin secretion, cause biological clock disorders, poor sleep quality, etc. In addition, the yellow phosphor will age with the use time, resulting in problems such as a decrease in the luminous efficiency of the LED and color temperature drift. Therefore, the method of synthesizing white light by combining blue light chips with yellow phosphors has serious deficiencies.

[0004] Synthesizing white light using multi-color LED chips has the advantages of long life, continuously adjustable spectrum and high light quality, and has a broader prospect in the fields of intelligent lighting, health lighting and visible light communication. Multi-primary-color white light LEDs can effectively solve the problems of color temperature drift and blue light leakage caused by phosphor aging during the use of phosphor-converted LEDs. According to the prediction of the LED lighting plan released by the US Department of Energy, the limit efficiency of phosphor-converted white light LEDs is about 250 lm / W, while the limit efficiency of multi-primary-color white light LEDs is about 350 lm / W. Therefore, high-quality, high-reliability and high-light-efficiency multi-primary-color white light LEDs are an inevitable trend for the next generation of green and healthy lighting.

[0005] In LED packaging, optical regulation is an essential part, which directly affects the light extraction efficiency and mixing efficiency of LEDs and is a key link to meet the requirements of multi-primary-color LED lighting applications. Traditional packaging structures such as the flip-chip package and SMD package cannot meet the requirements of uniform mixing and high extraction efficiency of multi-primary-color LEDs. When using multi-primary-color LEDs to directly synthesize white light, the spatial distribution positions of different color LED chips are different. Due to the mismatch of the light intensities of different color LED chips at different angles, the color temperatures of the light emitted from the LED packaging module are inconsistent in all spatial viewing angles, resulting in a color temperature deviation. Moreover, when applying the multi-primary-color LED packaging module to a lamp, the secondary lens of the lamp will exacerbate the color temperature deviation at different spatial viewing angles, especially in the case of large viewing angles, and even color separation may occur, resulting in the target plane obtaining not the white light synthesized by the multi-primary-color chips but regional color spots, greatly reducing the lighting quality and not meeting the requirements of high-quality lighting. Summary of the Invention

[0006] The first object of the present invention is to provide a phosphor-free multi-primary-color LED packaging structure. This packaging structure uses a packaging colloid layer doped with scattering particles to solve the problem of non-uniform light emission of different color LED chips, not only improving the spatial color uniformity but also ensuring a high light extraction efficiency at the same time.

[0007] The second object of the present invention is to provide a phosphor-free multi-primary-color LED packaging method. This packaging method avoids the use of phosphors, simplifies the packaging process, and at the same time improves the reliability of the packaging module, and can solve the defects of excessive blue light emission, lack of cyan light, and insufficient red light in the traditional packaging method.

[0008] The first object of the present invention is achieved as follows:

[0009] A phosphor-free multi-primary-color LED packaging structure, characterized in that it includes a packaging substrate, several LED chips placed at intervals, a die bonding layer, leads, and a composite packaging glue structure; several LED chips bonded through the die bonding layer are provided on the packaging substrate, each LED chip is connected to the substrate circuit through a lead, and a composite packaging glue structure is provided on the LED chip. The composite packaging glue structure is composed of a first packaging glue layer of pure packaging glue and a second packaging glue layer doped with micro-nano scattering particles, and the second packaging glue layer is located around the first packaging glue layer. In this way, it is ensured that most of the light directly exits from the first packaging glue layer, and the light at large angles undergoes scattering with the micro-nano scattering particles in the second packaging glue layer doped with micro-nano scattering particles, thereby improving the angular uniformity of the light emission of different LED chips, realizing mixing of light at large viewing angles, and at the same time ensuring a high light extraction efficiency.

[0010] Furthermore, the composite encapsulation glue structure realizes light extraction and light mixing of multi-primary color LED chips, wherein the first encapsulation glue layer is one of a hemisphere cap lens structure, a spherical segment lens structure, a spherical frustum lens structure, a circular frustum lens structure, a free-form surface lens structure, a trapezoidal structure lens structure, a square lens structure, a cylindrical lens structure or a polygonal lens structure.

[0011] Furthermore, the height h of the first encapsulation glue layer in the vertical direction is 1 mm to 50 mm, the characteristic length s of the first encapsulation glue layer [1] in the horizontal direction is 2 mm to 100 mm, and the ratio s1 / s3 of the characteristic length s1 at the top of the first encapsulation glue layer to the characteristic length s3 at the bottom in the horizontal direction is 0 to 1.

[0012] Furthermore, the thickness s2 of the second encapsulation glue layer in the horizontal direction is 0 mm to 50 mm, the horizontal direction thickness is constant or gradually changing in the vertical direction, and the height of the second encapsulation glue layer in the vertical direction is the same as or less than the height of the first encapsulation glue layer in the vertical direction.

[0013] Furthermore, the material of the first encapsulation glue layer is one of silicone, polyurethane or epoxy resin. Since the refractive index of the LED light-emitting surface material is relatively large (for example, the refractive index of GaP is 3.32 and that of GaN is 2.5), total internal reflection will occur at the encapsulation glue-air interface, resulting in only light at certain angles being able to exit the device, and light at other larger angles being reflected back into the chip and unable to be extracted. The refractive index of the encapsulation glue is between the LED device material and air. By utilizing the refractive index difference between different materials, the critical total internal reflection angle can be increased to achieve light extraction.

[0014] Furthermore, the second encapsulation glue layer is one of silicone, polyurethane or epoxy resin doped with micro-nano scattering particles. The micro-nano scattering particles are silicone resin, polycarbonate or polymethyl methacrylate organic micro-nano scattering particles, or the micro-nano scattering particles are inorganic micro-nano scattering particles such as silicon dioxide, titanium dioxide, aluminum nitride, zirconium dioxide, barium sulfate or calcium carbonate. The particle size of the micro-nano scattering particles is 0.005 μm to 20 μm, and the doping concentration of the micro-nano scattering particles is 0.001% to 20%.

[0015] Furthermore, at least two types of LED chips with different wavelengths are provided on the encapsulation substrate. The LED chips are GaN binary material chips or AlGaNP quaternary material chips, and the LED chips are arranged and distributed in a circular or polygonal shape. According to the theory of colorimetry, different color temperatures of light can be achieved by using LED chips with different wavelengths. For example, golden yellow light with a low color temperature can be synthesized by using two LED chips with different wavelengths of yellow light and red light; white light of five primary colors with a high color rendering index can be synthesized by using five LED chips with different wavelengths of blue light, cyan light, green light, yellow light, and red light.

[0016] Furthermore, one of encapsulation glue, high-reflectivity reflective glue, high-reflectivity reflective paint, or encapsulation glue doped with high-concentration scattering particles is dot-coated around the LED chip. The purpose is to reduce the light absorption on the side walls of the chip and increase the light extraction.

[0017] Furthermore, the encapsulation substrate is one of a copper substrate, an aluminum substrate, a silicon substrate, a ceramic substrate, or a PCB board, and the reflective layer on the surface of the encapsulation substrate is a high-reflectivity reflective paint layer or a high-reflectivity reflective glue layer. Due to the total reflection and Fresnel reflection at the encapsulation glue-air interface, part of the light is reflected back to the encapsulation substrate, and the light extraction is increased through the high-reflectivity coating on the substrate.

[0018] The second object of the present invention is achieved as follows:

[0019] A method for encapsulating a phosphor-free multi-primary color LED achieves high spatial color uniformity through a second encapsulation glue layer doped with micro-nano scattering particles. The specific implementation steps are as follows:

[0020] A: Prepare several LED chips with two or more different wavelengths, and bond several spaced LED chips through a die attach layer;

[0021] B: Adopt the wire bonding process to connect the upper electrode of the chip to the circuit on the encapsulation substrate through gold wire, aluminum wire, copper wire, or silver wire to achieve electrical connection;

[0022] C: Prepare encapsulation glue, and use the mold top or dot coating process to make a first encapsulation glue layer on the encapsulation substrate to achieve the light extraction of different LED chips, and heat the first encapsulation glue layer to cure the first encapsulation glue layer;

[0023] D: Uniformly mix micron scattering particles or nano scattering particles with the encapsulation glue, and use the mold top or dot coating process to make a second encapsulation glue layer doped with micro-nano scattering particles around the first encapsulation glue layer to achieve the mixing of light of different LED chips, and heat the entire encapsulation module to cure the second encapsulation glue layer to obtain a finished product.

[0024] Compared with the prior art, the above technical solutions proposed by the present invention have the following advantages:

[0025] 1. The phosphor-free multi-primary-color LED packaging structure proposed by the present invention uses a composite packaging colloid layer doped with scattering particles to solve the problems of uneven light emission of different color LED chips, light mixing and light extraction of multi-primary-color LED packaging. The scattering effect of micro-nano scattering particles not only improves the spatial color uniformity, but also ensures a high light extraction efficiency at the same time, and improves the problem of light loss caused by the backward scattering of micro-nano particles. At the same time, by directly synthesizing white light with multi-primary-color LED chips, the full-spectrum light emission has a more ideal light color quality, and truly realizes green, healthy and high-quality LED lighting;

[0026] 2. The phosphor-free multi-primary-color LED packaging method proposed by the present invention avoids the use of phosphors, simplifies the packaging process, and at the same time improves the reliability of the packaging module, and can solve the defects of excessive blue light emission, lack of cyan light and insufficient red light in the traditional packaging method. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Figure 1 Schematic diagram of the packaging structure of Embodiment 1 of the present invention;

[0028] Figure 2 Schematic diagram of the distribution of multi-primary-color LED chips on the substrate in Embodiment 1 of the present invention;

[0029] Figure 3 Schematic diagram of the three-dimensional structure of the packaging module in Embodiment 1 of the present invention;

[0030] Figure 4 Comparison diagram of the color temperature change of the traditional ball cap packaging structure and the packaging structure of Embodiment 1 of the present invention with respect to the spatial viewing angle;

[0031] Figure 5 Comparison diagram of the color temperature change of the traditional ball cap packaging structure and the packaging structure of Embodiment 2 of the present invention with respect to the spatial viewing angle;

[0032] Figure 6 Schematic diagram of the packaging structure of Embodiment 3 of the present invention;

[0033] Figure 7 Schematic diagram of the distribution of multi-primary-color LED chips on the substrate in Embodiment 3 of the present invention

[0034] Figure 8 Schematic diagram of the packaging structure of Embodiment 4 of the present invention;

[0035] Figure 9 Schematic diagram of the packaging structure of Embodiment 5 of the present invention;

[0036] Figure 10 Schematic diagram of the packaging structure of Embodiment 6 of the present invention;

[0037] Figure 11Schematic diagram of the distribution of the golden-yellow light LED chips in Embodiment 6 of the present invention on the substrate;

[0038] Figure 12 Schematic diagram of the packaging structure in Embodiment 7 of the present invention. Detailed implementation manners

[0039] The present invention will be further described below in conjunction with embodiments and in comparison with the accompanying drawings.

[0040] Embodiment 1:

[0041] As Figure 1 shown, a phosphor-free multi-primary-color LED packaging structure includes a ceramic substrate 11, four LED chips 13 placed at intervals, a die bonding layer 12, leads 14, and composite packaging adhesive layers 16 and 17; the four LED chips 13 placed at intervals are bonded to the ceramic substrate 11 through the die bonding layer 12, the LED chips 13 are connected to the substrate circuit 15 through the leads 14, and there are composite packaging adhesive layers 16 and 17 on the LED chips 13. The composite packaging adhesive layer consists of a first packaging adhesive layer 16 and a second packaging adhesive layer 17 doped with micro-nano scattering particles, and the second packaging adhesive layer 17 is located around the first packaging adhesive layer 16.

[0042] Among them, the material of the first packaging adhesive layer 16 is silica gel. The first packaging adhesive layer 16 is in the shape of a frustum of a cone. The height h of the first packaging adhesive layer 16 in the vertical direction is 4 mm. The characteristic lengths s1 and s3 of the first packaging adhesive layer 16 in the horizontal direction at the top and bottom are 12 mm and 15 mm respectively. The ratio s1 / s3 of the characteristic length s1 of the first packaging adhesive layer at the top in the horizontal direction to the characteristic length s3 of the first packaging adhesive layer at the bottom in the horizontal direction is 0.8. The height h of the second packaging adhesive layer 17 in the vertical direction is 4 mm. The thickness of the second packaging adhesive layer 17 in the horizontal direction is constant, and the horizontal thickness s2 is 1.5 mm. The material of the second packaging adhesive layer 17 is silica gel doped with scattering particles. The scattering particles are silicone resin particles, and the doping concentration is 0.6 wt%. The average particle size of the scattering particles is 2 μm.

[0043] As Figure 1 shown, a phosphor-free multi-primary-color LED packaging method improves the spatial color uniformity of the multi-primary-color LED through the second packaging layer doped with micro-nano particles. The specific implementation steps are as follows:

[0044] 1. First, bond the LED chips 13 to the ceramic substrate 11 through the silver paste die bonding layer 12 to achieve the electrical connection between the lower electrodes of the chips 13 and the circuit 15 on the ceramic substrate 11; the arrangement of the 4 LED chips 13 on the ceramic substrate 11 is as Figure 2As shown in the figure, the four LED chips 13 are composed of a blue LED chip 131 with a main wavelength of 460 nm, a green LED chip 132 with a main wavelength of 520 nm, a yellow LED chip 133 with a main wavelength of 560 nm, and a red LED chip 134 with a main wavelength of 620 nm, and are distributed at intervals in a square arrangement on the ceramic substrate 11;

[0045] 2. Adopt the wire bonding process, and connect the upper electrode of the chip 13 to the circuit 15 on the ceramic substrate 11 through the lead 14 to achieve electrical connection;

[0046] 3. Adopt the die-top process to make a spherical table-shaped first encapsulation glue layer 16 on the ceramic substrate 11 to achieve light extraction of different LED chips, heat and cure the first encapsulation glue layer 16, bake and heat it through an oven, with a heating temperature of 150 °C and a heating time of 0.5 hours;

[0047] 4. Uniformly mix the micro-nano particles with the encapsulation glue, and adopt the die-top process to make a second encapsulation glue layer 17 doped with micro-nano particles around the first encapsulation glue layer 16 to achieve color mixing of different LED chips, and heat and cure the entire encapsulation module, with a heating temperature of 150 °C and a heating time of 1 hour.

[0048] As Figure 3 shown is a three-dimensional structure schematic diagram of an encapsulation module with a composite encapsulation structure, including a ceramic substrate 11, a chip 13, a first encapsulation glue layer 16, and a second encapsulation glue layer 17. This method uses a micro-nano particle-doped encapsulation glue layer to improve the light output distribution of different colors of LED chips, thereby improving the spatial color uniformity.

[0049] As Figure 4 shown is a comparison diagram of the color temperature of the traditional ball-cap encapsulation structure and the encapsulation structure of this embodiment changing with the spatial viewing angle. It can be seen from the figure that by adopting the encapsulation structure of this embodiment, high spatial color uniformity of the light output of the multi-primary-color LED encapsulation structure is achieved.

[0050] Example 2:

[0051] The structure of Example 2 is basically the same as that of Example 1. The difference from Example 1 is that the scattering particles used in Example 2 are an inorganic material TiO2, the doping concentration of TiO2 is 0.6 wt%, and the particle size of TiO2 is 2 μm.

[0052] As Figure 5 shown is a comparison diagram of the color temperature of the traditional ball-cap encapsulation structure and the encapsulation structure of Example 2 changing with the spatial viewing angle. It can be seen from the figure that by adopting the encapsulation structure of this embodiment, high spatial color uniformity of the light output of the multi-primary-color LED encapsulation structure is achieved.

[0053] Example 3:

[0054] As Figure 6As shown in the figure, a phosphor-free multi-color LED packaging structure includes an aluminum substrate 61, five LED chips 63 placed at intervals, a die bonding layer 62, leads 64, and composite encapsulation glue layers 66 and 67. The five LED chips 63 placed at intervals are bonded to the aluminum substrate 61 through the die bonding layer 62. The LED chips 63 are connected to the substrate circuit 65 through the leads 64. There are composite encapsulation glue layers 66 and 67 on the LED chips 63. The composite encapsulation glue layer consists of a first encapsulation glue layer 66 and a second encapsulation glue layer 67 doped with micro-nano scattering particles, and the second encapsulation glue layer 67 is located around the first encapsulation glue layer 66.

[0055] Among them, the material of the first encapsulation glue layer 16 is epoxy resin. The first encapsulation glue layer 66 is a cylindrical structure. The height h of the first encapsulation glue layer 66 in the vertical direction is 10 mm. The characteristic length s of the first encapsulation glue layer 66 is 30 mm. The characteristic lengths s1 and s3 of the top and bottom of the first encapsulation glue layer 66 in the horizontal direction are both 30 mm. The ratio s1 / s3 of the characteristic length s1 of the top of the first encapsulation glue layer in the horizontal direction to the characteristic length s3 of the bottom in the horizontal direction is 1. The height h of the second encapsulation glue layer 67 in the vertical direction is 10 mm. The thickness of the second encapsulation glue layer 67 in the horizontal direction is constant, and the horizontal thickness s2 is 5 mm. The material of the second encapsulation glue layer 67 is epoxy resin doped with scattering particles. The scattering particles are zirconia, and the doping concentration is 5 wt%. The average particle size of the scattering particles is 5 μm.

[0056] The arrangement of the 5 LED chips 63 on the aluminum substrate 61 is as Figure 7 shown. The 5 LED chips 63 are composed of a blue LED chip 631 with a main wavelength of 460 nm, a cyan LED chip 632 with a main wavelength of 485 nm, a green LED chip 633 with a main wavelength of 520 nm, a yellow LED chip 634 with a main wavelength of 560 nm, and a red LED chip 635 with a main wavelength of 620 nm, and are distributed at intervals in a circular arrangement on the aluminum substrate 61.

[0057] Example 4:

[0058] As Figure 8 shown, a phosphor-free multi-color LED packaging structure includes a copper substrate 81, several LED chips 83 placed at intervals, a die bonding layer 82, leads 84, and composite encapsulation glue layers 86 and 88. The several LED chips 83 placed at intervals are bonded to the copper substrate 81 through the die bonding layer 82. The LED chips 83 are connected to the substrate circuit 85 through the leads 84. There are composite encapsulation glue layers 86 and 87 on the LED chips 83. The composite encapsulation glue layer consists of a first encapsulation glue layer 86 and a second encapsulation glue layer 87 doped with micro-nano scattering particles, and the second encapsulation glue layer 87 is located around the first encapsulation glue layer 86.

[0059] Among them, the material of the first encapsulation glue layer 16 is polyurethane. The first encapsulation glue layer 86 has a ball cap structure. The height h of the first encapsulation glue layer 86 in the vertical direction is 6 mm. The characteristic lengths s1 and s3 of the top and bottom of the first encapsulation glue layer 86 in the horizontal direction are 0 mm and 20 mm respectively. The ratio s1 / s3 of the characteristic length s1 at the top of the first encapsulation glue layer to the characteristic length s3 at the bottom in the horizontal direction is 0. The height h of the second encapsulation glue layer 87 in the vertical direction is 4 mm. The thickness s2 of the second encapsulation glue layer 87 in the horizontal direction is gradually changing. The thickness s2 in the horizontal direction gradually changes from 0 to 2 mm from top to bottom in the vertical direction. The material of the second encapsulation glue layer 87 is epoxy resin doped with scattering particles. The scattering particles are polycarbonate, with a concentration of 10 wt%, and the average particle size of the scattering particles is 8 μm.

[0060] Example 5:

[0061] As Figure 9 shown, a phosphor-free multi-primary-color LED encapsulation structure includes a silicon substrate 91, four LED chips 93 placed at intervals, a die bonding layer 92, leads 94, and composite encapsulation glue layers 96 and 97. The four LED chips 93 placed at intervals are bonded to the silicon substrate 91 through the die bonding layer 92. The LED chips 93 are connected to the substrate circuit 95 through the leads 94. There are composite encapsulation glue layers 96 and 97 on the LED chips 93. The composite encapsulation glue layer is composed of a first encapsulation glue layer 96 and a second encapsulation glue layer 97 doped with micro-nano scattering particles, and the second encapsulation glue layer 97 is located around the first encapsulation glue layer 96.

[0062] Among them, the material of the first encapsulation glue layer 96 is silica gel. The first encapsulation glue layer 96 has a cylindrical structure with a curved top surface. The height h of the first encapsulation glue layer 96 in the vertical direction is 35 mm. The characteristic lengths s1 and s3 of the top and bottom of the first encapsulation glue layer 96 in the horizontal direction are 0 mm and 50 mm respectively. The ratio s1 / s3 of the characteristic length s1 at the top of the first encapsulation glue layer to the characteristic length s3 at the bottom in the horizontal direction is 0. The height h of the second encapsulation glue layer 97 in the vertical direction is 25 mm. The thickness s2 of the second encapsulation glue layer 97 in the horizontal direction is gradually changing. The thickness s2 in the horizontal direction gradually changes from 0 to 10 mm from top to bottom in the vertical direction. The material of the second encapsulation glue layer 77 is silica gel doped with scattering particles. The scattering particles are silicon dioxide, with a concentration of 10 wt%, and the average particle size of the scattering particles is 1 μm.

[0063] Example 6:

[0064] As Figure 10As shown in the figure, a phosphor-free multi-primary-color LED packaging structure includes a ceramic substrate 101, four LED chips 103 placed at intervals, a die bonding layer 102, leads 104, and composite encapsulation glue layers 106 and 107; the four LED chips 103 placed at intervals are bonded to the ceramic substrate 101 through the die bonding layer 102, the LED chips 103 are connected to the substrate circuit 105 through the leads 104, and there are composite encapsulation glue layers 106 and 107 on the LED chips 103. The composite encapsulation glue layer consists of a first encapsulation glue layer 106 and a second encapsulation glue layer 107 doped with micro-nano scattering particles, and the second encapsulation glue layer 107 is located around the first encapsulation glue layer 106.

[0065] A white glue layer 109 with a high diffuse reflectivity is fabricated on the surface of the encapsulation substrate 101, and a white glue 108 with a high diffuse reflectivity is dot-coated around the LED chips 103. The thickness of the white glue 108 with a high diffuse reflectivity dot-coated around the LED chips 103 is the same as the thickness of the LED chips, both being 0.2 mm. The arrangement of the 4 LED chips 103 on the ceramic substrate 101 is as Figure 11 shown. The 4 LED chips 103 are composed of two yellow LED chips 1031 with a peak wavelength of 560 nm and two red LED chips 1032 with a peak wavelength of 620 nm, and are distributed at intervals in a rectangular arrangement on the ceramic substrate 101. The material of the first encapsulation glue layer 106 is silica gel. The first encapsulation glue layer 106 is in the shape of a truncated cone. The height h in the vertical direction of the first encapsulation glue layer 106 is 4 mm. The characteristic lengths s1 and s3 in the horizontal direction at the top and bottom of the first encapsulation glue layer 106 are 12 mm and 15 mm respectively. The ratio s1 / s3 of the characteristic length s1 in the horizontal direction at the top of the first encapsulation glue layer to the characteristic length s3 in the horizontal direction at the bottom is 0.8. The height h in the vertical direction of the second encapsulation glue layer 107 is 4 mm. The thickness in the horizontal direction of the second encapsulation glue layer 107 is constant, and the thickness s2 in the horizontal direction is 1.5 mm. The material of the second encapsulation glue layer 107 is silica gel doped with scattering particles. The scattering particles are barium sulfate particles, the doping concentration is 1 wt%, and the average particle size of the scattering particles is 2 μm.

[0066] Example 7:

[0067] As Figure 12As shown in the figure, a phosphor-free multi-primary-color LED packaging structure includes a ceramic substrate 121, four LED chips 123 placed at intervals, a die bonding layer 122, leads 124, and composite encapsulation glue layers 126 and 127; the four LED chips 123 placed at intervals are bonded to the ceramic substrate 121 through the die bonding layer 122, the LED chips 123 are connected to the substrate circuit 125 through the leads 124, and there are composite encapsulation glue layers 126 and 127 on the LED chips 123. The composite encapsulation glue layer is composed of a first encapsulation glue layer 126 and a second encapsulation glue layer 127 doped with micro-nano scattering particles, and the second encapsulation glue layer 127 is located around the first encapsulation glue layer 126.

[0068] A silver layer 128 with a high reflectivity is vapor-deposited on the surface of the ceramic substrate 121. The material of the first encapsulation glue layer 126 is silica gel. The first encapsulation glue layer 126 is in the shape of a frustum of a cone. The height h of the first encapsulation glue layer 126 in the vertical direction is 4 mm. The characteristic lengths s1 and s3 in the horizontal direction at the top and bottom of the first encapsulation glue layer 126 are 12 mm and 15 mm respectively. The ratio s1 / s3 of the characteristic length s1 in the horizontal direction at the top of the first encapsulation glue layer to the characteristic length s3 in the horizontal direction at the bottom is 0.8. The height h of the second encapsulation glue layer 127 in the vertical direction is 4 mm. The thickness in the horizontal direction of the second encapsulation glue layer 127 is constant, and the thickness s2 in the horizontal direction is 1.5 mm. The material of the second encapsulation glue layer 127 is silica gel doped with scattering particles. The scattering particles are barium sulfate particles, the doping concentration is 1 wt%, and the average particle size of the scattering particles is 2 μm.

[0069] The above is the preferred embodiment of the present invention, but the present invention should not be limited to the content disclosed in this embodiment and the drawings. Therefore, all equivalent or modified implementations completed without departing from the spirit disclosed by the present invention fall within the protection scope of the present invention.

Claims

1. A phosphor-free multi-primary color LED package structure, characterized by: The invention comprises a packaging substrate, a plurality of spaced-apart LED chips of two or more different wavelengths, a die-bonding layer, leads, and a composite packaging adhesive structure. The packaging substrate is provided with a plurality of LED chips bonded via the die-bonding layer, each LED chip being connected to the substrate circuit via leads. The composite packaging adhesive structure is provided on the LED chips, and the composite packaging adhesive structure comprises a first packaging adhesive layer of pure packaging adhesive and a second packaging adhesive layer doped with micro-nano scattering particles, wherein the second packaging adhesive layer is located around the first packaging adhesive layer. The horizontal thickness of the second packaging adhesive layer is constant in the vertical direction or gradually increases from top to bottom. A white adhesive layer with high diffuse reflectivity is formed on the surface of the packaging substrate, and the white adhesive with high diffuse reflectivity is dotted around the LED chips. in, The first encapsulation layer is spherical, and the ratio s1 / s3 of the horizontal characteristic length s1 of the top of the first encapsulation layer to the horizontal characteristic length s3 of the bottom is 0.

8. The vertical height of the second encapsulation layer is the same as the height of the spherical shape, both being 4 mm. The horizontal thickness of the second encapsulation layer is constant, and the horizontal thickness s2 is 1.5 mm. or, The first encapsulation layer has a cylindrical structure, a vertical height h of 10 mm, a characteristic length s of the first encapsulation layer of 30 mm, and characteristic horizontal lengths s1 and s3 of the top and bottom of the first encapsulation layer of 30 mm. The ratio s1 / s3 of the characteristic horizontal length s1 of the top and the characteristic horizontal length s3 of the bottom of the first encapsulation layer is 1. The second encapsulation layer has a vertical height h of 10 mm and a constant horizontal thickness s2 of 5 mm. or, The first encapsulating adhesive layer is a spherical cap structure, with a vertical height h of 6 mm, and characteristic horizontal lengths s1 and s3 of 0 mm and 20 mm at the top and bottom, respectively. The ratio s1 / s3 of the characteristic horizontal length s1 at the top and the characteristic horizontal length s3 at the bottom of the first encapsulating adhesive layer is 0. The second encapsulating adhesive layer has a vertical height h of 4 mm and a gradient horizontal thickness s2, which gradiently changes from 0 to 2 mm from top to bottom in the vertical direction. or, The first encapsulation adhesive layer is a cylindrical structure with a curved top surface, and its vertical height h is 35 mm. The characteristic horizontal lengths s1 and s3 of the top and bottom of the first encapsulation adhesive layer are 0 mm and 50 mm respectively, and the ratio s1 / s3 of the characteristic horizontal length s1 of the top and the characteristic horizontal length s3 of the bottom of the first encapsulation adhesive layer is 0; the vertical height h of the second encapsulation adhesive layer is 25 mm, and the horizontal thickness s2 is gradual, and the horizontal thickness s2 gradually changes from 0 to 10 mm from top to bottom in the vertical direction.

2. The phosphor-free multi-primary color LED package structure according to claim 1, characterized in that: The material of the first packaging adhesive layer is one of silicone, polyurethane or epoxy resin.

3. The phosphor-free multi-primary color LED package structure according to claim 1, characterized in that: The second encapsulation adhesive layer is one of silica gel, polyurethane or epoxy resin doped with micro-nano scattering particles. The micro-nano scattering particles are one of silicone resin, polycarbonate or polymethyl methacrylate, silicon dioxide, titanium dioxide, aluminum nitride, zirconium dioxide, barium sulfate or calcium carbonate. The particle size of the micro-nano scattering particles is 0.005μm to 20μm.

4. The phosphor-free multi-primary color LED package structure according to claim 1, characterized in that: At least two LED chips with different wavelengths are arranged on the packaging substrate. The LED chips are GaN binary material chips or AlGaNP quaternary material chips. The LED chips are arranged and distributed in a circular or polygonal shape.

5. The phosphor-free multi-primary color LED package structure according to claim 1, characterized in that: The packaging substrate is one of a copper substrate, an aluminum substrate, a silicon substrate, a ceramic substrate or a PCB board.

6. A phosphor-free multi-primary color LED packaging method, characterized by: High spatial color uniformity is achieved through a second encapsulation adhesive layer doped with micro-nano scattering particles. The specific implementation steps are as follows: A: Prepare a number of LED chips with two or more different wavelengths and bond these LED chips spaced apart using a die-bonding layer; B: Use a wire bonding process to connect the top electrode of the chip to the circuit on the encapsulation substrate using gold, aluminum, copper, or silver wire to achieve electrical connection; C: Prepare encapsulation glue, use a mold top or dispensing process to make a first encapsulation glue layer on the encapsulation substrate to extract light from different LED chips, and heat the first encapsulation glue layer to cure it; D: Evenly mix the micron scattering particles or nano scattering particles with the encapsulation adhesive, and use a mold top or spot coating process to form a second encapsulation adhesive layer doped with micro-nano scattering particles around the first encapsulation adhesive layer to achieve mixed light from different LED chips. The entire encapsulation module is heated to cure the second encapsulation adhesive layer to obtain a finished product; in, The first encapsulation layer is spherical, and the ratio s1 / s3 of the horizontal characteristic length s1 of the top of the first encapsulation layer to the horizontal characteristic length s3 of the bottom is 0.

8. The vertical height of the second encapsulation layer is the same as the height of the spherical shape, both being 4 mm. The horizontal thickness of the second encapsulation layer is constant, and the horizontal thickness s2 is 1.5 mm. or, The first encapsulation layer has a cylindrical structure, a vertical height h of 10 mm, a characteristic length s of the first encapsulation layer of 30 mm, and characteristic horizontal lengths s1 and s3 of the top and bottom of the first encapsulation layer of 30 mm. The ratio s1 / s3 of the characteristic horizontal length s1 of the top and the characteristic horizontal length s3 of the bottom of the first encapsulation layer is 1. The second encapsulation layer has a vertical height h of 10 mm and a constant horizontal thickness s2 of 5 mm. or, The first encapsulating adhesive layer is a spherical cap structure, with a vertical height h of 6 mm, and characteristic horizontal lengths s1 and s3 of 0 mm and 20 mm at the top and bottom, respectively. The ratio s1 / s3 of the characteristic horizontal length s1 at the top and the characteristic horizontal length s3 at the bottom of the first encapsulating adhesive layer is 0. The second encapsulating adhesive layer has a vertical height h of 4 mm and a gradient horizontal thickness s2, which gradiently changes from 0 to 2 mm from top to bottom in the vertical direction. or, The first encapsulation adhesive layer is a cylindrical structure with a curved top surface, and its vertical height h is 35 mm. The characteristic horizontal lengths s1 and s3 of the top and bottom of the first encapsulation adhesive layer are 0 mm and 50 mm respectively, and the ratio s1 / s3 of the characteristic horizontal length s1 of the top and the characteristic horizontal length s3 of the bottom of the first encapsulation adhesive layer is 0; the vertical height h of the second encapsulation adhesive layer is 25 mm, and the horizontal thickness s2 is gradual, and the horizontal thickness s2 gradually changes from 0 to 10 mm from top to bottom in the vertical direction.

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