High light efficiency COB packaging structure
By introducing a first encapsulating layer and a second encapsulating layer stacked sequentially in the COB packaging structure, and by utilizing light-scattering particles and patterned structures to improve light emission efficiency, the problems of light attenuation and color temperature drift are solved, thus achieving high-efficiency COB packaging.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Utility models(China)
- Current Assignee / Owner
- FOSHAN EVERCORE OPTOELECTRONICS TECH
- Filing Date
- 2025-07-10
- Publication Date
- 2026-06-26
AI Technical Summary
In existing COB packaging structures, light is weakened by absorption by the substrate and encapsulating adhesive during multiple reflections, resulting in reduced luminous efficiency. Furthermore, uneven gravity distribution on curved surfaces causes color temperature drift, affecting the luminous effect.
The structure employs a first encapsulating layer and a second encapsulating layer stacked sequentially. The first encapsulating layer is used to seal the LED chip and achieve a preset color temperature and emission color. The second encapsulating layer contains light-scattering particles and has a patterned structure. Light is smoothly emitted under the combined action of the light-scattering particles and the patterned structure.
It significantly improves the light emission efficiency, reduces the loss of light due to multiple reflections in the encapsulation layer, avoids color temperature drift, and maintains the stability of the luminescence effect.
Smart Images
Figure CN224419209U_ABST
Abstract
Description
Technical Field
[0001] This utility model relates to the field of COB packaging technology, and in particular to a high-efficiency COB packaging structure. 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 adhesive layer 3'. The encapsulating adhesive 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 adhesive layer and air. The substrate is often made of mirrored aluminum, and the reflected light is further reflected at the substrate. The light is absorbed and weakened by the substrate and encapsulating adhesive during multiple reflections until it encounters a dam 4' with diffuse reflection characteristics and a certain tilt angle, at which point it finally exits the encapsulating adhesive, significantly reducing luminous efficiency. While making the surface of the encapsulating adhesive curved can improve light emission efficiency to some extent, the uneven distribution of gravity on curved surfaces can lead to uneven distribution of phosphors in the encapsulating adhesive, causing color temperature drift and affecting the luminous effect. Utility Model Content
[0003] The technical problem to be solved by this utility model is to provide a high-efficiency COB packaging structure that improves luminous efficiency without affecting color temperature and / or emission color.
[0004] To address the aforementioned technical problems, this utility model provides a high-efficiency COB packaging structure, comprising a substrate, an LED chip, and an encapsulating adhesive layer; the substrate has a dam, the LED chip is disposed within the dam and electrically connected to the substrate, and the encapsulating adhesive layer covers the LED chip; the encapsulating adhesive layer comprises a first encapsulating adhesive layer and a second encapsulating adhesive layer stacked sequentially, the first encapsulating adhesive layer being used to seal the LED chip and achieve a preset color temperature and / or emission color, the second encapsulating adhesive layer containing light-scattering particles, and the surface of the second encapsulating adhesive layer away from the substrate having a patterned structure.
[0005] As an improvement to the above scheme, the graphical structure is one or more of the following: frustum, cone, pyramid, sphere, hemisphere, and spherical crown.
[0006] As an improvement to the above scheme, the astigmatic particles are arranged to form the patterned structure, and the particle size of the astigmatic particles is 0.2 mm to 1 mm.
[0007] As an improvement to the above scheme, the graphical structure includes an array of multiple identical spherical cap structures.
[0008] As an improvement to the above solution, the height of the spherical crown structure is less than or equal to the radius of its base.
[0009] As an improvement to the above scheme, the ratio of the height of the spherical crown structure to the radius of the bottom surface of the spherical crown structure is 1:(1~2.5).
[0010] As an improvement to the above scheme, there is a preset distance between adjacent spherical crown structures, and the ratio of the preset distance to the bottom radius of the spherical crown structure is 1:(1~2).
[0011] As an improvement to the above solution, the patterned structure is distributed on the first encapsulating adhesive layer in one or more of the following ways: triangular array, rectangular array, and hexagonal array.
[0012] As an improvement to the above solution, the thickness of the second encapsulating adhesive layer is 0.2 mm to 1 mm.
[0013] As an improvement to the above solution, the side of the first encapsulating adhesive layer away from the substrate has a planar structure.
[0014] The present invention has the following beneficial effects:
[0015] The high-efficiency COB packaging structure provided by this invention includes a first encapsulating layer and a second encapsulating layer stacked sequentially. The first encapsulating layer seals the LED chip and achieves a preset color temperature and / or emission color. The second encapsulating layer is doped with light-scattering particles and has a patterned structure, which can improve the light emission efficiency. The high-efficiency COB packaging structure provided by this invention can significantly improve luminous efficiency without affecting the performance of the first encapsulating layer. Attached Figure Description
[0016] Figure 1 This is a schematic diagram of an existing COB packaging structure;
[0017] Figure 2 This is a schematic diagram of a high-efficiency COB packaging structure provided in an embodiment of the present invention;
[0018] Figure 3 This is a schematic diagram of a high-efficiency COB packaging structure provided in another embodiment of the present invention;
[0019] Figure 4 This is a top view of a high-efficiency COB packaging structure provided in an embodiment of the present invention. Detailed Implementation
[0020] To make the objectives, technical solutions, and advantages of this utility model clearer, the following will describe this utility model in further detail with reference to the accompanying drawings. It is hereby declared that the terms "up," "down," "left," "right," "front," "back," "inner," and "outer," etc., appearing or about to appear in this document, are based solely on the accompanying drawings and are not intended to specifically limit this utility model.
[0021] like Figure 2 As shown, this utility model embodiment provides a high-efficiency COB packaging structure, including a substrate 1, an LED chip 2, and an encapsulating adhesive layer 3; the substrate 1 is provided with a dam 4, the LED chip 2 is disposed within the dam 4 and electrically connected to the substrate 1, and the encapsulating adhesive layer 3 covers the LED chip 2; the encapsulating adhesive layer 3 includes a first encapsulating adhesive layer 31 and a second encapsulating adhesive layer 32 stacked sequentially, the first encapsulating adhesive layer 31 is used to seal the LED chip 2 and achieve a preset color temperature and / or emission color, the second encapsulating adhesive layer 32 contains light-scattering particles, and the surface of the second encapsulating adhesive layer 32 away from the substrate 1 is provided with a patterned structure 321.
[0022] In conventional COB packaging structures, the encapsulating layer 3 is typically doped with phosphor particles. The encapsulating layer 3 has a high refractive index, while air has a low refractive index. Most of the light emitted by the LED chip 2 is totally internally reflected back to the substrate 1 at the interface between the encapsulating layer 3 and air. The substrate 1 is often made of mirrored aluminum, and the reflected light is then reflected again at the substrate 1. The light is weakened by absorption by the substrate 1 and the encapsulating layer during multiple reflections until it comes into contact with the dammed layer 4, which has diffuse reflection characteristics and a certain tilt angle, before finally escaping from the encapsulating layer. This process is detrimental to improving luminous efficiency. Although making the surface of the encapsulating layer curved can improve light emission efficiency to some extent, the uneven distribution of gravity on the curved surface can lead to uneven distribution of phosphor in the encapsulating layer 3, causing color temperature drift and affecting the luminous effect.
[0023] In the high-efficiency COB packaging structure provided by this utility model, the encapsulating adhesive layer 3 includes a first encapsulating adhesive layer 31 and a second encapsulating adhesive layer 32 stacked sequentially. The first encapsulating adhesive layer 31 is used to seal the LED chip 2 and achieve a preset color temperature and / or emission color. It can be understood that the first encapsulating adhesive layer 31 is doped with phosphor particles, and the second encapsulating adhesive layer 32 contains light-scattering particles. The second encapsulating adhesive layer 32 has a patterned structure 321 on the side away from the substrate 1. The light that was originally totally reflected at the interface between the encapsulating adhesive layer 3 and the air is smoothly emitted under the combined action of the light-scattering particles and the patterned structure 321, thereby improving the light emission efficiency. Moreover, the setting of the second encapsulating adhesive layer 32 does not affect the original structure and properties of the first encapsulating adhesive layer 31. In addition, due to the presence of the second encapsulating adhesive layer 32, the heat accumulation caused by multiple reflections of light in the encapsulating adhesive layer is reduced, effectively reducing light decay.
[0024] It is understood that the patterned structure 321 is one or more of the following shapes: frustum, cone, pyramid, sphere, and hemisphere. Compared to a plane, the patterned structure 321 can significantly reduce total internal reflection and improve light extraction efficiency.
[0025] In one embodiment, the light-scattering particles are arranged to form the patterned structure 321, and the particle size of the light-scattering particles is 0.2 mm to 1 mm. If the particle size of the light-scattering particles is too small, it is difficult to form a good scattering effect; if the particle size of the light-scattering particles is too large, a large amount of colloid is required to bind the light-scattering particles to form the second encapsulating adhesive layer 32. Preferably, the particle size of the light-scattering particles is 0.4 mm to 0.6 mm.
[0026] In a preferred embodiment, the patterned structure 321 includes an array of multiple identical spherical cap structures. The symmetry of the spherical cap structures ensures uniform scattering of light regardless of its direction of incidence, avoiding specific angle light spots that may occur with pyramidal structures. Furthermore, the radius of curvature of the spherical cap structures effectively reduces the probability of total internal reflection at the interface, further improving light extraction efficiency. Moreover, continuous curvature changes can disperse light over a wider angular range, making it particularly suitable for scenarios requiring wide-angle illumination.
[0027] In one implementation, such as Figure 2 and Figure 3 As shown, the height h of the spherical cap structure is less than or equal to the bottom radius r of the spherical cap structure. Setting the height h of the spherical cap structure to be less than or equal to the bottom radius r of the spherical cap structure can more effectively suppress total internal reflection of light at the interface, reduce the loss of light due to multiple reflections in the encapsulating adhesive layer 3, thereby further improving the light extraction efficiency. Moreover, the spherical cap structure can also prevent the light emitted from the second encapsulating adhesive layer 32 from interfering with each other.
[0028] Preferably, the ratio of the height h of the spherical crown structure to the bottom radius r of the spherical crown structure is 1:(1~2.5). Setting the ratio of the height h of the spherical crown structure to the bottom radius r of the spherical crown structure within a preset range can further adjust the light emission efficiency.
[0029] It is understood that adjacent spherical cap structures can be arranged closely together or spaced apart. For example... Figure 2 As shown, the hemispherical patterned structures 321 can be closely arranged, meaning there are no gaps between adjacent patterned structures 321. In a preferred embodiment, as... Figure 3 As shown, there is a preset distance s between adjacent spherical structures, and the ratio of the preset distance s to the base radius r of the spherical structure is 1:(1~2). If the ratio of the preset distance s to the base radius r of the spherical structure is too small, light may be reflected multiple times between the spherical structures of adjacent hemispheres, increasing absorption loss; if the ratio of the preset distance s to the base radius r of the spherical structure is too large, light may undergo total internal reflection at the spaced plane surfaces and not be effectively scattered by the spherical structures, increasing surface reflection loss.
[0030] On a top view, the patterned structure 321 is distributed on the first encapsulating adhesive layer 31 in one or more of the following ways: triangular array, rectangular array, and hexagonal array. For example... Figure 4 As shown, in one embodiment, the patterned structure 321 is distributed in a rectangular array on the first encapsulating adhesive layer 31.
[0031] It should be noted that the thickness d of the second encapsulating layer 32 also has a significant impact on the light extraction efficiency of the LED chip 2. In a preferred embodiment, the thickness d of the second encapsulating layer 32 is 0.2 mm to 1 mm. If the thickness d of the second encapsulating layer 32 is too small, the adhesive in the second encapsulating layer 32 may not be able to completely fill the gaps in the spherical cap structure, resulting in a decrease in the surface quality of the second encapsulating layer 32 and thus a decrease in scattering efficiency. If the thickness d of the second encapsulating layer 32 is too large, the material of the second encapsulating layer 32 will slightly absorb light, resulting in a longer absorption path and increased light loss. The thickness of the first encapsulating layer 31 can be the same as or slightly smaller than that of a conventional COB encapsulation structure, and is not specifically limited here.
[0032] In a preferred embodiment, the side of the first encapsulating adhesive layer 31 away from the substrate 1 has a planar structure, and the planar structure will not adversely affect the uniformity of phosphor distribution in the first encapsulating adhesive layer 31.
[0033] The packaging method for the high-efficiency COB light source includes the following steps:
[0034] S1. Provide a substrate.
[0035] Optionally, the substrate is one of a copper substrate, an aluminum substrate, a silicon substrate, a ceramic substrate, or a PCB board.
[0036] S2. A dam is set on the substrate.
[0037] S3. Install LED chips inside the dam and electrically connect the LED chips to the substrate.
[0038] S4. A first encapsulating adhesive layer is formed within the dam, wherein the first encapsulating adhesive layer is doped with phosphor particles and the first encapsulating adhesive layer at least covers the LED chip.
[0039] Specifically, the first encapsulating layer includes phosphor particles and encapsulating adhesive. The encapsulating adhesive can be one or more of silicone, polyurethane, and epoxy resin. The doping concentration of the phosphor particles in the first encapsulating layer is 15wt% to 50wt%.
[0040] S5. A second encapsulating layer is formed on the first encapsulating layer, wherein the second encapsulating layer is doped with light-scattering particles.
[0041] Specifically, the second encapsulating layer includes light-diffusing particles and encapsulating adhesive. The encapsulating adhesive can be one or more of silicone, polyurethane, and epoxy resin. The doping concentration of the light-diffusing particles in the second encapsulating layer is 80wt% to 95wt%.
[0042] In one embodiment, the second encapsulating adhesive layer is prepared by the following method:
[0043] (1) Mix the light-scattering particles and the encapsulating adhesive to obtain a mixed colloid.
[0044] (2) The mixed colloid is dispensed onto the surface of the first encapsulation adhesive layer, leveled, and cured to obtain the second encapsulation adhesive layer.
[0045] Specifically, after obtaining the mixed colloid, a needle with a diameter larger than that of the scattering particles is selected, and the mixed colloid is dispensed onto the surface of the first encapsulation adhesive layer using a dispensing machine. After natural leveling or accelerated leveling by centrifugal force, it is then baked and cured.
[0046] Understandably, due to the addition of a second encapsulating layer, the height of the dam can be increased compared to a conventional high-efficiency COB light source structure, so that the surface of the second encapsulating layer is flush with the top of the dam.
[0047] The above description is the preferred embodiment of this utility model. It should be noted that for those skilled in the art, several improvements and modifications can be made without departing from the principle of this utility model, and these improvements and modifications are also considered to be within the protection scope of this utility model.
Claims
1. A high-efficiency COB packaging structure, characterized in that, The device includes a substrate, an LED chip, and an encapsulating adhesive layer. A dam is provided on the substrate, and the LED chip is disposed within the dam and electrically connected to the substrate. The encapsulating adhesive layer covers the LED chip. The encapsulating adhesive layer includes a first encapsulating adhesive layer and a second encapsulating adhesive layer stacked sequentially. The first encapsulating adhesive layer is used to seal the LED chip and achieve a preset color temperature and / or emission color. The second encapsulating adhesive layer contains light-scattering particles, and the surface of the second encapsulating adhesive layer away from the substrate has a patterned structure.
2. The high-efficiency COB packaging structure as described in claim 1, characterized in that, The graphical structure is one or more of the following: frustum, cone, pyramid, sphere, hemisphere, and spherical crown.
3. The high-efficiency COB packaging structure as described in claim 1, characterized in that, The astigmatic particles are arranged to form the patterned structure, and the particle size of the astigmatic particles is 0.2 mm to 1 mm.
4. The high-efficiency COB packaging structure as described in claim 3, characterized in that, The graphical structure comprises an array of multiple identical spherical cap structures.
5. The high-efficiency COB packaging structure as described in claim 4, characterized in that, The height of the spherical crown structure is less than or equal to the radius of its base.
6. The high-efficiency COB packaging structure as described in claim 5, characterized in that, The ratio of the height of the spherical crown structure to the radius of its base is 1:(1~2.5).
7. The high-efficiency COB packaging structure as described in claim 4, characterized in that, There is a preset distance between adjacent spherical crown structures, and the ratio of the preset distance to the bottom radius of the spherical crown structure is 1:(1~2).
8. The high-efficiency COB packaging structure as described in claim 1, characterized in that, The patterned structure is distributed on the first encapsulating adhesive layer in one or more of the following ways: triangular array, rectangular array, and hexagonal array.
9. The high-efficiency COB packaging structure as described in claim 1, characterized in that, The thickness of the second encapsulating adhesive layer is 0.2mm to 1mm.
10. The high-efficiency COB packaging structure as described in claim 1, characterized in that, The side of the first encapsulating adhesive layer away from the substrate has a planar structure.