COB high luminous efficiency packaging structure and packaging method

Abstract

The invention discloses a COB high luminous efficiency packaging structure and a packaging method. The COB high luminous efficiency packaging structure comprises a mirror surface aluminum substrate, a plurality of normal LED chips, a reflection scattering layer and a packaging glue layer. The mirror surface aluminum substrate is provided with a solid crystal area, and the plurality of normal LED chips are arranged in the solid crystal area at intervals and are electrically connected with the mirror surface aluminum substrate; a reflecting and scattering layer is arranged among the plurality of normally-mounted LED chips, and a preset distance is formed between the bottom of the reflecting and scattering layer and the adjacent normally-mounted LED chips; the reflectivity of the reflecting and scattering layer is smaller than that of the mirror surface aluminum substrate; and the packaging adhesive layer covers the normally-mounted LED chip and the reflection and scattering layer. By adopting the COB high-luminous-efficiency packaging structure provided by the invention, the problem of yellow spots can be improved while the luminous efficiency is improved.

Description

Technical Field

[0001] This invention relates to the field of COB packaging technology, and in particular to a COB high-efficiency packaging structure and packaging method. Background Technology

[0002] Multi-chip COB (Chip On Board) packaging is a low-cost packaging method that directly attaches multiple LED chips to a substrate using die bond adhesive, thereby significantly shortening the process flow. Figure 1 The existing COB (Chip-on-Board) packaging structure includes a substrate 1', an LED chip 2', and an encapsulating layer 3'. The encapsulating layer has a high refractive index, while air has a low refractive index. Most of the light emitted by the LED chip is totally internally reflected back to the substrate at the interface between the encapsulating layer and air. Since the substrate is often made of mirrored aluminum, the reflected light is further reflected at the substrate. The light is weakened by absorption by the substrate and encapsulating layer during multiple reflections until it reaches a dam 4' with diffuse reflection characteristics and a certain tilt angle, at which point it finally exits the encapsulating layer. This significantly reduces luminous efficiency. Furthermore, the light after multiple total internal reflections is fully excited by the phosphor in the encapsulating layer 3', resulting in an overall yellowish color. Finally, the light exits at the dam 4', causing a yellowish ring to form on the outermost edge. While coating the substrate surface with white oil or creating a microporous structure on the substrate surface can reduce total internal reflection losses, this approach has drawbacks such as affecting the substrate's reflectivity and presenting processing difficulties. Summary of the Invention

[0003] The technical problem to be solved by the present invention is to provide a COB high luminous efficiency packaging structure that can improve luminous efficiency while improving the macular problem.

[0004] To address the aforementioned technical problems, this invention provides a COB high-efficiency packaging structure, comprising a mirrored aluminum substrate, multiple upright LED chips, a reflective and scattering layer, and an encapsulating adhesive layer.

[0005] The mirror aluminum substrate has a die-bonding area, and a plurality of upright LED chips are spaced apart in the die-bonding area and electrically connected to the mirror aluminum substrate.

[0006] A reflective scattering layer is provided between multiple upright LED chips, and the bottom of the reflective scattering layer is at a predetermined distance from the adjacent upright LED chip; the reflectivity of the reflective scattering layer is less than the reflectivity of the mirror aluminum substrate;

[0007] The encapsulating adhesive layer covers the upright LED chip and the reflective scattering layer.

[0008] As an improvement to the above scheme, the total reflectivity of the reflection and scattering layer is 90% to 95%, and the diffuse reflectivity of the reflection and scattering layer is 85% to 92%.

[0009] As an improvement to the above solution, the preset distance is 50μm to 150μm;

[0010] The top surface of the upright LED chip is higher than the top surface of the reflective scattering layer; the thickness difference between the top surface of the reflective scattering layer and the top surface of the upright LED chip is 50μm to 100μm.

[0011] As an improvement to the above solution, the sidewall of the reflective scattering layer forms a preset angle with the surface of the mirror aluminum substrate, the preset angle being 55° to 85°.

[0012] As an improvement to the above scheme, the reflective scattering layer has an island-like structure, with each sidewall of the reflective scattering layer forming a first reflective surface and the top surface of each reflective scattering layer forming a second reflective surface, wherein the radius of curvature of the first reflective surface is smaller than the radius of curvature of the second reflective surface.

[0013] As an improvement to the above solution, the ratio of the surface area of ​​the mirror aluminum substrate to the surface area of ​​the reflective scattering layer is 1:(0.05~0.3).

[0014] As an improvement to the above scheme, the reflective scattering layer includes white reflective particles and an adhesive, wherein the weight ratio of the white reflective particles to the adhesive is (0.2~0.5):1;

[0015] The white reflective particles have a particle size of 0.5 μm to 1.5 μm.

[0016] As an improvement to the above scheme, the white reflective particles include a first white reflective particle and a second white reflective particle, wherein the reflectivity of the first reflective particle is greater than 90%, and the refractive index of the second white reflective particle is greater than 1.8; the weight ratio of the first reflective particle to the second white reflective particle is (2.5~4.5):1.

[0017] As an improvement to the above scheme, the first white reflective particles include one or more of titanium dioxide powder, barium sulfate powder, and aluminum oxide powder; the particle size of the first white reflective particles is 1 μm to 1.5 μm.

[0018] The second white reflective particles include one or more of titanium oxide powder, boron nitride powder, magnesium oxide powder, and zirconium oxide powder; the particle size of the second white reflective particles is 0.5 μm to 1 μm.

[0019] Accordingly, the present invention also provides a COB high-efficiency encapsulation method for preparing the above-mentioned high-efficiency COB encapsulation structure, comprising the following steps:

[0020] Provide a mirror-finished aluminum substrate;

[0021] Die-bonding adhesive is applied in dots to the die-bonding area of ​​the mirror aluminum substrate;

[0022] Apply reflective scattering adhesive between adjacent die-bonding regions;

[0023] A positive-mount LED chip is disposed within the die-bonding region;

[0024] The die-attach adhesive and reflective scattering adhesive are cured to fix the upright LED chip and form a reflective scattering layer;

[0025] The upright LED chip is electrically connected to the mirrored aluminum substrate;

[0026] An encapsulating adhesive layer is formed on the upright LED chip and the reflective scattering layer.

[0027] Implementing this invention has the following beneficial effects:

[0028] In the high-efficiency COB packaging structure provided by this invention, a reflective scattering layer is provided between the upright LED chips. The bottom of the reflective scattering layer is at a preset distance from the adjacent upright LED chip, and the reflectivity of the reflective scattering layer is less than that of the mirror aluminum substrate. While not affecting the reflection of light emitted from the side of the upright LED chip by the mirror aluminum substrate, the diffuse reflection effect of the reflective scattering layer is fully utilized to improve the light emission efficiency of the upright LED chip, thereby improving the luminous efficiency and significantly improving the yellow spot problem. Attached Figure Description

[0029] Figure 1 This is a schematic diagram of an existing COB packaging structure;

[0030] Figure 2 This is a schematic diagram of a COB high-efficiency packaging structure provided in an embodiment of the present invention;

[0031] Figure 3 This is a schematic diagram of a COB high-efficiency packaging structure provided in an embodiment of the present invention;

[0032] Figure 4 yes Figure 3 Enlarged view of part A;

[0033] Figure 5 This is a schematic flowchart of a COB high-efficiency packaging method provided in an embodiment of the present invention. Detailed Implementation

[0034] To make the objectives, technical solutions, and advantages of the present invention more apparent, the present invention will be further described in detail below with reference to the accompanying drawings. It is hereby stated that any directional terms such as "up," "down," "left," "right," "front," "back," "inside," and "outside" that appear or will appear herein are based solely on the accompanying drawings and are not intended to limit the present invention.

[0035] like Figure 2 and Figure 3 As shown, this embodiment of the invention provides a COB high-efficiency packaging structure, including a mirror aluminum substrate 1, multiple upright LED chips 2, a reflective and scattering layer 3, and an encapsulating adhesive layer 4;

[0036] The mirror aluminum substrate 1 is provided with a die bonding area, and a plurality of upright LED chips 2 are spaced apart in the die bonding area and electrically connected to the mirror aluminum substrate 1.

[0037] A reflective scattering layer 3 is provided between multiple upright LED chips 2, and the bottom of the reflective scattering layer 3 is at a preset distance S from the adjacent upright LED chip 2; the reflectivity of the reflective scattering layer 3 is less than the reflectivity of the mirror aluminum substrate 1;

[0038] The encapsulating adhesive layer 4 covers the upright LED chip 2 and the reflective scattering layer 3.

[0039] In the high-efficiency COB packaging structure provided by the present invention, a reflective scattering layer 3 is provided between the upright LED chips 2. The bottom of the reflective scattering layer 3 is at a preset distance S from the adjacent upright LED chips 2, and the reflectivity of the reflective scattering layer 3 is less than that of the mirror aluminum substrate 1. While not affecting the reflection of light emitted from the side of the upright LED chips 2 by the mirror aluminum substrate 1, the diffuse reflection effect of the reflective scattering layer 3 is fully utilized to improve the light emission efficiency of the upright LED chips 2, thereby improving the luminous efficiency and significantly improving the yellow spot problem.

[0040] In one embodiment, the total reflectivity of the reflective scattering layer 3 is 90%–95%, and the diffuse reflectivity is 85%–92%. It is understood that the total reflectivity and diffuse reflectivity of the reflective scattering layer 3 are determined using the integrating sphere method. Specifically, the sample is placed at the sample test port. After light is reflected by the sample, it is reflected multiple times by the inner surface of the integrating sphere, and finally the exit angle of the light is measured from the detector, which is the total reflectivity of the sample, including specular reflection and diffuse reflection. A light trap is set symmetrically on the sphere with respect to the light entrance aperture. After light is reflected by the sample, specularly reflected light exits from the light trap, while diffusely reflected light is reflected by the inner surface of the integrating sphere and finally detected by the detector, which is the diffuse reflectivity of the sample. The reflective scattering layer 3 can randomly scatter and reflect the light emitted by the upright LED chip 2, avoiding the loss caused by multiple total internal reflections and improving light extraction efficiency. Under the action of the reflective scattering layer 3, the light from adjacent upright LED chips 2 cross-mixes, which can enhance the uniformity of light mixing, increase the emission angle, and avoid the generation of color spots and yellow spots. The addition of the reflective scattering layer 3 can also reduce the energy accumulation of light in specific areas, avoid local overheating which can exacerbate the thermal quenching of phosphors, and extend the phosphor's lifespan.

[0041] In a preferred embodiment, the preset distance S is 50μm to 150μm. Reserving the preset distance S ensures sufficient space for the reflective and scattering layer 3 while also considering the reliability of the die bonding process for the upright LED chip 2.

[0042] In one embodiment, the top surface of the upright LED chip 2 is higher than the top surface of the reflective scattering layer 3. Light emitted from the side of the upright LED chip 2 can be substantially blocked and refracted by the reflective scattering layer 3, minimizing light loss caused by absorption by adjacent upright LED chips 2. In a preferred embodiment, the thickness difference H is 50 μm to 100 μm.

[0043] The sidewall of the reflective scattering layer 3 forms a preset angle θ with the surface of the mirror aluminum substrate 1, wherein the preset angle θ is 55° to 85°. The tilted sidewall alters the light reflection path, making it easier for light emitted from the sidewall of the upright LED chip 2 to exit the light surface and avoid absorption by the mirror aluminum substrate 1. Simultaneously, the preset angle θ reduces the probability of total internal reflection at the interface between the upright LED chip 2 and the reflective scattering layer 3, resulting in multiple cross-mixing of light from adjacent upright LED chips 2 within the reflective scattering layer 3, leading to a more uniform light distribution. In a preferred embodiment, the preset angle θ is 55° to 85°. Controlling the preset angle θ within this preferred range balances luminous efficiency and uniformity. If the preset angle θ is too small, the light still strikes the mirror aluminum substrate 1 at a high angle, resulting in insufficient reflection; if the preset angle θ is too large, the light is excessively concentrated towards the center, leading to uneven light distribution. Optionally, the sidewall of the reflective scattering layer 3 can be a flat or curved surface. In one embodiment, the sidewall of the reflective scattering layer 3 is planar, and the angle θ between the plane of the sidewall and the horizontal plane of the mirror aluminum substrate 1 is 55° to 85°. Setting the sidewall as planar can improve the manufacturing efficiency. In another embodiment, the sidewall is curved. Setting the sidewall as curved increases the area of ​​the sidewall, allowing light to be fully refracted and reflected on the sidewall of the curved surface, further improving the light extraction efficiency. Specifically, the curved surface can be formed by the reflective scattering layer 3 protruding towards the upright LED chip 2, and the angle θ between the tangent at the apex of the curved surface and the horizontal plane of the mirror aluminum substrate 1 is 55° to 85°.

[0044] In a preferred embodiment, such as Figure 3 and Figure 4As shown, the reflective scattering layer 3 has an island-like structure. Each reflective scattering layer 3 has a sidewall forming a first reflective surface 31 and a top surface forming a second reflective surface 32. The radius of curvature of the first reflective surface 31 is smaller than that of the second reflective surface 32. The first reflective surface 31 with a larger radius of curvature is more gently sloping, resulting in a more concentrated reflected beam, approximating specular reflection, weaker scattering, and energy concentrated in the specular reflection direction. The second reflective surface 32 with a smaller radius of curvature is sharper, resulting in a more divergent reflected beam, which can generate more diffuse reflection or lateral scattering, thus reducing total internal reflection on the surface of the mirror aluminum substrate and improving luminous efficiency while ensuring light emission from the sidewalls.

[0045] In one embodiment, the ratio of the surface area of ​​the mirror aluminum substrate 1 to the surface area of ​​the reflective scattering layer 3 is 1:(0.05 to 0.3), exemplarily 1:0.08, 1:0.1, 1:0.15, 1:0.2, or 1:0.25, but not limited thereto. The increased diffuse reflection area is controlled to be 5% to 30% of the area of ​​the mirror aluminum substrate 1, changing the angle of the total internal reflection light without reducing the high reflectivity of the mirror aluminum substrate 1.

[0046] In one embodiment, the mirror aluminum substrate 1 is further provided with a dam 5, and the upright LED chip 2 is disposed within the dam 5.

[0047] In one embodiment, the reflective scattering layer 3 comprises white reflective particles and an adhesive, wherein the weight ratio of the white reflective particles to the adhesive is (0.2–0.5):1, exemplarily 0.25:1, 0.3:1, 0.35:1, 0.4:1, or 0.45:1, but is not limited thereto. A weight ratio that is too small will make it difficult to achieve a good reflective scattering effect, while a weight ratio that is too large will cause the white reflective particles to settle, affecting the reflective scattering effect. The adhesive can be epoxy resin or silicone, etc., and is not specifically limited here.

[0048] The white reflective particles have a particle size of 0.5 μm to 1.5 μm. If the particle size of the white reflective particles is too small, some light will be strongly scattered, resulting in color distortion. At the same time, small-sized white reflective particles are more likely to agglomerate, affecting the uniformity of the reflective scattering layer 3. If the particle size of the white reflective particles is too large, the scattering cross-section of the white reflective particles is too large, reducing the diffuse reflection effect. At the same time, the white luminescent particles have a fast settling velocity and are prone to accumulating at the bottom of the reflective scattering layer 3, affecting the reflection and scattering effects.

[0049] In a preferred embodiment, the white reflective particles include a first white reflective particle and a second white reflective particle. The first white reflective particle has a reflectivity greater than 90%, and the second white reflective particle has a refractive index greater than 1.8. The weight ratio of the first white reflective particle to the second white reflective particle is (2.5–4.5):1, exemplarily 2.8:1, 3:1, 3.5:1, 4:1, or 4.2:1, but not limited thereto. The first white reflective particle can directly reflect light, while the second white reflective particle enhances light scattering through the refractive index difference, breaking the total internal reflection path and improving light extraction efficiency. Simultaneously, the second white reflective particle can selectively modulate specific wavelengths to match the excitation spectrum of the phosphor in the encapsulating adhesive layer 4, improving color uniformity.

[0050] Preferably, the first white reflective particles comprise one or more of titanium dioxide powder, barium sulfate powder, and aluminum oxide powder. The particle size of the first white reflective particles is 1 μm to 1.5 μm.

[0051] The second white reflective particles comprise one or more of titanium oxide powder, boron nitride powder, magnesium oxide powder, and zirconium oxide powder. The particle size of the second white reflective particles is 0.5 μm to 1 μm.

[0052] Mixing white reflective particles of different sizes can reduce curing shrinkage stress and decrease the risk of cracking. The second white reflective particle can fill the gaps between the first white reflective particles. After mixing, the white reflective particles of different sizes form a reflective scattering adhesive with the adhesive, which can also prevent agglomeration and sedimentation, adjust the viscosity of the system, and make the reflective scattering adhesive easier to apply and less prone to overflow and diffusion.

[0053] More preferably, the first white reflective particle is barium sulfate powder with a particle size of 1.2 μm, and the second white reflective particle is boron nitride powder with a particle size of 0.6 μm. Barium sulfate has a high refractive index, which can shorten the optical path of scattering and refraction, reduce light absorption, and achieve high reflectivity with a relatively thin reflective scattering layer. The addition of boron nitride powder fills the pores of the large-particle-size barium sulfate powder, increasing the refractive index. At the same time, the high thermal conductivity of boron nitride powder can also improve the overall heat dissipation performance of the COB packaging structure. Through the synergistic effect of large-particle-size barium sulfate powder and small-particle-size boron nitride powder, the reflection, refraction, and thermal conductivity of the reflective scattering layer are coordinated, thereby better balancing the light efficiency and thermal stability of the COB packaging structure.

[0054] Correspondingly, such as Figure 5 As shown, this embodiment of the invention also provides a COB high-efficiency encapsulation method for preparing the above-mentioned high-efficiency COB encapsulation structure, comprising the following steps:

[0055] S1. Provide a mirror-finished aluminum substrate.

[0056] The mirror aluminum substrate can reflect the side light of the upright LED chip to the light-emitting surface, reducing the absorption loss of the mirror aluminum substrate and improving the light extraction efficiency. Moreover, the mirror aluminum substrate can quickly conduct heat from the upright LED chip, with little impact on the thermal conductivity of the packaged device.

[0057] In one embodiment, circuit wiring can be achieved by setting an insulating layer and copper circuits on a mirror aluminum substrate, or by using DPC technology. This method is compatible with various die bonding materials such as silver paste and solder paste. The specific wiring method is not specifically limited here.

[0058] S2. Apply die bond adhesive to the die bond area of ​​the mirror aluminum substrate.

[0059] Die-attach adhesive is used to fix upright LED chips. Optional materials include silver paste, solder paste, insulating silicone, etc., without specific limitations.

[0060] S3. Apply reflective scattering adhesive between adjacent solidification zones.

[0061] It is understood that the order of S2 and S3 is not specifically limited here. That is to say, the die bond adhesive can be applied first and then the reflective scattering adhesive can be applied, or the reflective scattering adhesive can be applied first and then the die bond adhesive can be applied, or a die bonder with dual adhesive trays can be used to apply the die bond adhesive and the reflective scattering adhesive simultaneously.

[0062] In one embodiment, the reflective scattering layer can also be obtained by photolithography of reflective scattering adhesive. If the reflective scattering layer is formed by photolithography, it can be formed before die bonding, and then the upright LED chip can be die bonded and wire bonded. Specifically, the reflective scattering adhesive is applied to the light-emitting surface of the mirror aluminum substrate using a dispensing machine or stencil printing, and then the mask is irradiated with a UV lamp to wash away the excess, thus obtaining the reflective scattering layer.

[0063] S4. Place a positively mounted LED chip in the die-bonding area. Make the LED chip contact with the die-bonding material.

[0064] S5. Cure the die bond adhesive and reflective scattering adhesive to fix the upright LED chip and form a reflective scattering layer.

[0065] S6. Electrically connect the upright LED chip to the mirror aluminum substrate.

[0066] S7. An encapsulating adhesive layer is formed on the upright LED chip and the reflective scattering layer.

[0067] The COB high-efficiency packaging method provided by this invention can realize the setting of the reflective and scattering layer between small-pitch upright LED chips without adding any additional complex processes, resulting in high manufacturing efficiency.

[0068] The present invention will be further described below with reference to specific embodiments:

[0069] Example 1

[0070] This embodiment provides a high-efficiency COB packaging structure, including a mirror aluminum substrate, multiple upright LED chips, a reflective scattering layer, and an encapsulating adhesive layer. A die-bonding region is provided on the mirror aluminum substrate, and multiple upright LED chips are spaced apart within the die-bonding region and electrically connected to the mirror aluminum substrate. A reflective scattering layer is provided between the multiple upright LED chips, and the bottom of the reflective scattering layer is at a predetermined distance of 100 μm from the adjacent upright LED chip. The reflectivity of the reflective scattering layer is less than the reflectivity of the mirror aluminum substrate. The encapsulating adhesive layer covers the upright LED chips and the reflective scattering layer.

[0071] The total reflectivity of the reflection-scattering layer is 92%, and the diffuse reflectivity of the reflection-scattering layer is 88%.

[0072] The top surface of the reflective scattering layer is flush with the top surface of the mounted LED chip.

[0073] The sidewalls of the reflective scattering layer are perpendicular to the surface of the mirror aluminum substrate.

[0074] The ratio of the surface area of ​​the mirror aluminum substrate to the surface area of ​​the reflective scattering layer is 1:0.1.

[0075] The reflective scattering layer consists of white reflective particles and an adhesive, with a weight ratio of 0.6:1. The white reflective particles have a particle size of 2 μm and are titanium dioxide powder.

[0076] The packaging method for a high-efficiency COB packaging structure includes the following steps:

[0077] S1. Provide a mirror-finished aluminum substrate.

[0078] S2. Apply die bond adhesive to the die bond area of ​​the mirror aluminum substrate.

[0079] S3. Apply reflective scattering adhesive between adjacent solidification zones.

[0080] S4. Set the positive LED chip in the die bonding area.

[0081] S5. Curing die bond adhesive and reflective scattering adhesive to fix the upright LED chip and form a reflective scattering layer.

[0082] S6. Electrically connect the standard LED chip to the mirrored aluminum substrate.

[0083] S7. Form an encapsulating adhesive layer on the upright LED chip and the reflective scattering layer.

[0084] Example 2

[0085] This embodiment provides a high-efficiency COB light source, which differs from Embodiment 1 in that the top surface of the upright LED chip is higher than the top surface of the reflective scattering layer, with a thickness difference of 60 μm. All other aspects are the same as in Embodiment 1.

[0086] Example 3

[0087] This embodiment provides a high-efficiency COB light source, which differs from Embodiment 2 in that the sidewall of the reflective scattering layer is planar, and the sidewall of the reflective scattering layer forms a preset angle with the surface of the mirror aluminum substrate, the preset angle being 65°. All other aspects are the same as in Embodiment 2.

[0088] Example 4

[0089] This embodiment provides a high-efficiency COB light source, which differs from Embodiment 3 in that the sidewall of each reflective scattering layer forms a first reflective surface, and the top surface of each reflective scattering layer forms a second reflective surface. The radius of curvature of the first reflective surface is smaller than that of the second reflective surface. All other aspects are the same as in Embodiment 3.

[0090] Example 5

[0091] This embodiment provides a high-efficiency COB light source, which differs from Embodiment 4 in that the reflective scattering layer includes white reflective particles and an adhesive, with a weight ratio of white reflective particles to adhesive of 0.4:1. The white reflective particles have a particle size of 1.2 μm and are titanium dioxide powder. All other aspects are the same as in Embodiment 4.

[0092] Example 6

[0093] This embodiment provides a high-efficiency COB light source, which differs from Embodiment 5 in that the white reflective particles include a first white reflective particle and a second white reflective particle. The first reflective particle is barium sulfate powder with a particle size of 1.2 μm, and the second white reflective particle is boron nitride powder with a particle size of 0.6 μm. The weight ratio of the first reflective particle to the second white reflective particle is 3:1. All other aspects are the same as in Embodiment 5.

[0094] Comparative Example 1

[0095] This comparative example provides a high-efficiency COB light source, which differs from Example 1 in that the mirror aluminum substrate, except for the die-bonding area where the upright LED chip is fixed, is coated with a reflective scattering layer, and the thickness of the reflective scattering layer is 50μm.

[0096] The COB packaging structures obtained in Examples 1 to 6 and Comparative Example 1 were used to power the chips with a constant current source at 42V and 1.2A DC. The steady state was defined as the chip remaining lit continuously for 50 minutes. Performance testing was then performed.

[0097] (1) Light emission angle: The light intensity distribution in each direction is measured by the light distribution curve measurement method, and the angle range in which the light intensity drops to 10% is calculated.

[0098] (2) Luminous efficiency: The luminous efficiency under steady state was tested by integrating sphere spectroscopy.

[0099] (3) Color uniformity: The color uniformity of each angle in the space is tested by using the two-dimensional illuminance distribution analysis method, and the CIE uniformity is calculated.

[0100] (4) Macular condition: Observe with the naked eye whether there is a macular spot, and calculate the CCT spatial variation value ΔCCT when the spatial correlated color temperature of the light source spot is 4500K.

[0101] The specific test results are shown in the table below.

[0102]

[0103]

[0104] The above is a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and modifications can be made without departing from the principles of the present invention. These improvements and modifications are also considered to be within the scope of protection of the present invention.

Claims

1. A COB high-efficiency luminous efficacy packaging structure, characterized in that, Includes a mirrored aluminum substrate, multiple upright LED chips, a reflective and scattering layer, and an encapsulating adhesive layer; The mirror aluminum substrate has a die-bonding area, and a plurality of upright LED chips are spaced apart in the die-bonding area and electrically connected to the mirror aluminum substrate. A reflective scattering layer is provided between multiple upright LED chips, and the bottom of the reflective scattering layer is at a predetermined distance from the adjacent upright LED chip; the reflectivity of the reflective scattering layer is less than the reflectivity of the mirror aluminum substrate; The encapsulating adhesive layer covers the upright LED chip and the reflective scattering layer.

2. The COB high-efficiency packaging structure as described in claim 1, characterized in that, The total reflectivity of the reflective scattering layer is 90%–95%, and the diffuse reflectivity of the reflective scattering layer is 85%–92%.

3. The COB high-efficiency packaging structure as described in claim 1, characterized in that, The preset distance is 50μm to 150μm; The top surface of the upright LED chip is higher than the top surface of the reflective scattering layer; the thickness difference between the top surface of the reflective scattering layer and the top surface of the upright LED chip is 50μm to 100μm.

4. The COB high-efficiency packaging structure as described in claim 1, characterized in that, The sidewall of the reflective scattering layer forms a preset angle with the surface of the mirror aluminum substrate, and the preset angle is 55° to 85°.

5. The COB high-efficiency packaging structure as described in claim 1, characterized in that, The reflective scattering layer has an island-like structure, with each sidewall of the reflective scattering layer forming a first reflective surface and the top surface of each reflective scattering layer forming a second reflective surface. The radius of curvature of the first reflective surface is smaller than the radius of curvature of the second reflective surface.

6. The COB high-efficiency packaging structure as described in claim 1, characterized in that, The ratio of the surface area of ​​the mirror aluminum substrate to the surface area of ​​the reflective scattering layer is 1:(0.05~0.3).

7. The COB high-efficiency packaging structure as described in claim 1, characterized in that, The reflective scattering layer comprises white reflective particles and an adhesive, wherein the weight ratio of the white reflective particles to the adhesive is (0.2-0.5):1; The white reflective particles have a particle size of 0.5 μm to 1.5 μm.

8. The COB high-efficiency packaging structure as described in claim 7, characterized in that, The white reflective particles include a first white reflective particle and a second white reflective particle. The first reflective particle has a reflectivity greater than 90%, and the second white reflective particle has a refractive index greater than 1.

8. The weight ratio of the first reflective particle to the second white reflective particle is (2.5 to 4.5):

1.

9. The COB high-efficiency packaging structure as described in claim 8, characterized in that, The first white reflective particles include one or more of titanium dioxide powder, barium sulfate powder, and aluminum oxide powder; the particle size of the first white reflective particles is 1 μm to 1.5 μm. The second white reflective particles include one or more of titanium oxide powder, boron nitride powder, magnesium oxide powder, and zirconium oxide powder; the particle size of the second white reflective particles is 0.5 μm to 1 μm.

10. A method for high-efficiency COB packaging, used to prepare the high-efficiency COB packaging structure as described in any one of claims 1 to 9, characterized in that, Includes the following steps: Provide a mirror-finished aluminum substrate; Die-bonding adhesive is applied in dots to the die-bonding area of ​​the mirror aluminum substrate; Apply reflective scattering adhesive between adjacent die-bonding regions; A positive-mount LED chip is disposed within the die-bonding region; The die-attach adhesive and reflective scattering adhesive are cured to fix the upright LED chip and form a reflective scattering layer; The upright LED chip is electrically connected to the mirrored aluminum substrate; An encapsulating adhesive layer is formed on the upright LED chip and the reflective scattering layer.

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