A white light COB light source with high uniformity and its processing method

Abstract

This application belongs to the field of semiconductor packaging, and particularly relates to a white light COB light source with high uniformity, which includes: a base, the base includes a support body and pits arrayed on one side surface of the support body; light-emitting chips, the light-emitting chips are correspondingly arranged at the bottoms of the pits one by one; a first encapsulation layer, filled at the bottoms of the pits and at least wrapping part of the side light-emitting surfaces of the light-emitting chips; a phosphor layer, the phosphor layer is arranged on the surface of the first encapsulation layer, and the first encapsulation layer and the phosphor layer jointly wrap the front light-emitting surface and the side light-emitting surfaces of the light-emitting chips. This application has the effect of eliminating light leakage halos.

Description

Technical Field

[0001] This application relates to the field of semiconductor packaging, and particularly to a high-uniformity white light COB light source and its processing method. Background Art

[0002] LED light sources have a wide range of applications in various fields due to their low cost and good lighting effects. Currently, low-cost white light sources are mainly achieved by exciting multi-color phosphors with blue LED chips. The most common technical solution is to use blue LED chips to excite yellow phosphors, and the emitted yellow light and blue light are mixed to form white light.

[0003] With the improvement of living standards, there are also requirements for the color temperature of white light sources. In order to adjust the warmth and coolness of the light, other wavelength phosphors need to be added on the basis of the original yellow phosphors. Specifically, more red phosphors are doped in low-color-temperature white light sources, and more short-wave phosphors and less red phosphors are doped in high-color-temperature white light sources.

[0004] In high-color-temperature white light sources, because the amount of red phosphors used is small, it is difficult to cover the side light-emitting surface of the blue LED chip, resulting in the direct leakage of blue light that is not doped with red from the side of the blue LED chip, causing a distinct blue halo to be doped in the final light-emitting spot, which affects the uniformity of the light-emitting effect. Therefore, a white light source structure is urgently needed to eliminate the blue halo caused by the light leakage of the blue LED chip. Summary of the Invention

[0005] To solve the above problems and make the light-emitting uniformity of the white light source better, on the first aspect, this application provides a high-uniformity white light COB light source.

[0006] The high-uniformity white light COB light source provided by this application adopts the following technical solutions:

[0007] A high-uniformity white light COB light source, comprising:

[0008] A base, the base includes a support body and pits arrayed on one side surface of the support body;

[0009] Light-emitting chips, the light-emitting chips are correspondingly arranged at the bottoms of the pits one by one;

[0010] A first encapsulation layer, filled at the bottoms of the pits and at least covering part of the side light-emitting surfaces of the light-emitting chips;

[0011] A phosphor layer, the phosphor layer is arranged on the surface of the first encapsulation layer, and the first encapsulation layer and the phosphor layer jointly cover the front light-emitting surface and the side light-emitting surfaces of the light-emitting chips.

[0012] By adopting the above technical solution, the light emitted by the light-emitting chip reaches the phosphor layer after propagating in the first encapsulation layer, exciting the phosphor in the phosphor layer, avoiding the occurrence of light leakage, and improving the light-emitting uniformity of the COB light source.

[0013] Optionally, the pit includes a reflection part for arranging the chip and a dam part connected to the reflection part, and the diameter of the reflection part gradually increases from the bottom towards the dam part;

[0014] The diameter of the dam part is a fixed value or the diameter of the dam part gradually decreases from the position connected to the reflection part towards the position away from the reflection part.

[0015] By adopting the above technical solution, the gradually increasing diameter of the reflection part can reflect the light towards the light-emitting direction, improving the light-emitting efficiency; the edge of the dam part can provide surface tension for the phosphor glue in the pit, facilitating dot convexity.

[0016] Optionally, on the cross-section passing through the optical axis of any of the light-emitting chips, the inner wall of the corresponding reflection part is a part of a parabola, and the light-emitting chip is located at the focus position of the parabola;

[0017] Or, on the cross-section passing through the optical axis of any of the light-emitting chips, the inner wall of the corresponding reflection part forms an angle of 130° - 140° with the bottom of the pit.

[0018] By adopting the above technical solution, the light emitted from the side light-emitting surface of the light-emitting chip is approximately parallel after reflection, enabling the light emitted by the light source to have higher collimation.

[0019] Optionally, it further includes a second encapsulation layer, which covers the surface of the phosphor layer facing away from the light-emitting chip, and the surface of the second encapsulation layer away from the light-emitting chip is a plane.

[0020] By adopting the above technical solution, the second encapsulation layer completely covers the light-emitting side of the device, avoiding hydrolysis failure caused by the exposure of the phosphor layer to the air.

[0021] Optionally, the first encapsulation layer is doped with light-diffusing spheres for making the light propagate in all directions in the first encapsulation layer; the concentration of the light-diffusing spheres increases from the light-emitting chip towards the inner wall of the pit.

[0022] By adopting the above technical solution, the first encapsulation layer has a light homogenizing effect on the light, and the light emitted by the light-emitting chip is transmitted to the phosphor layer more uniformly, improving the stimulated emission efficiency in the phosphor layer. Moreover, the first encapsulation layer near the light-emitting end has a weak scattering ability, and the first encapsulation layer far from the light-emitting end has a strong scattering ability, making the surface of the first encapsulation layer near the light-emitting side have a relatively uniform light density.

[0023] Optionally, the phosphor layer includes:

[0024] A first phosphor layer, which is sprayed on the side of the first encapsulation layer away from the bottom of the pit, and the first phosphor layer and the first encapsulation layer jointly wrap the front light-emitting surface and the side light-emitting surface of the light-emitting chip;

[0025] A second phosphor glue layer, which is dispensed in the pit, and the upper surface of the second phosphor glue layer is flush with or higher than the edge of the pit;

[0026] A third phosphor layer, which is sprayed on the side of the second phosphor glue layer away from the first phosphor layer, covering the upper surface of the second phosphor glue layer and the surface of the carrier between adjacent pits.

[0027] By adopting the above technical solution, on the one hand, the first phosphor layer and the third phosphor glue have smaller thicknesses and larger phosphor densities, leaving enough processing space for the second phosphor glue layer on the premise of ensuring the dimming effect; on the other hand, the second phosphor glue layer has a lower phosphor density, separating the first phosphor layer and the third phosphor layer, avoiding an overly thick high-density phosphor layer, and ensuring the light transmittance. The combination of the two enables the COB light source to have a higher light efficiency.

[0028] Optionally, the edge of the second phosphor glue layer fits the edge of the pit, and the middle of the second phosphor glue layer bulges and is higher than the surface of the carrier.

[0029] By adopting the above technical solution, the opposite two side surfaces of the second phosphor glue layer are not flush. When light is reflected back and forth in the second phosphor glue layer, each time it reaches the same side surface, it has a different incident angle. Even if it cannot exit due to the angle problem for the first time, the angle will change during subsequent back-and-forth reflections until the exit condition is met, thereby improving the light utilization rate.

[0030] Optionally, the powder concentration in the first phosphor layer is greater than the powder concentration in the third phosphor layer; and / or

[0031] The wavelengths of the light emitted after the first phosphor layer, the second phosphor glue layer, and the third phosphor layer are excited decrease in sequence.

[0032] By adopting the above technical solution, light is more likely to pass through the third phosphor layer and is more likely to be reflected by the first phosphor layer. During the process of light reflection between the third phosphor layer and the first phosphor layer, light is more likely to exit from the side of the third phosphor layer; during the process of light propagating from bottom to top, the light emitted by stimulated emission of the lower layer will not be absorbed by the phosphor of the upper layer. The phosphor mainly absorbs the short-wave light emitted by the light-emitting chip during stimulated emission, which can improve the light extraction efficiency.

[0033] In a second aspect, the present application provides a processing method for a white light COB light source with high uniformity.

[0034] The processing method for a white light COB light source with high uniformity provided by the present application adopts the following technical solution:

[0035] A processing method for a white light COB light source with high uniformity includes the following steps:

[0036] B1. Provide a lamp holder and a base provided on the lamp holder;

[0037] B2. Open a plurality of recesses arranged in an array on one side of the base;

[0038] B3. Correspondingly arrange a light-emitting chip at the bottom of each recess;

[0039] B4. Fill encapsulation glue around the light-emitting chip to form a first encapsulation layer;

[0040] B5. Process a phosphor layer on the surface of the first encapsulation layer and the light-emitting chip;

[0041] B6. Coat encapsulation glue on the side of the phosphor layer facing away from the light-emitting chip to form a second encapsulation layer, and the surface of the second encapsulation layer away from the light-emitting chip is a plane.

[0042] By adopting the above technical solution, the phosphor layer directly wraps the surface of the light-emitting chip or indirectly wraps it via the first encapsulation layer, avoiding light leakage and improving the uniformity of light extraction.

[0043] Optionally, the step B5 includes:

[0044] Spray phosphor glue on the surface of the first encapsulation layer and the light-emitting chip to form a first phosphor layer;

[0045] Dot glue on the side of the first phosphor layer facing away from the light-emitting chip to prepare a second phosphor glue layer. The edge of the second phosphor glue layer in each recess is flush with the edge of the recess, and the center of the second phosphor glue layer bulges and is higher than the base;

[0046] A phosphor glue layer is sprayed on the surface of the base between the second phosphor glue layer and the adjacent pit to form a third phosphor layer.

[0047] By adopting the above technical solution, when the space above the light-emitting chip is limited, the uniform coating of the first phosphor layer, the second phosphor glue layer and the third phosphor glue layer is ensured, and the light transmittance is also ensured.

[0048] In summary, the present application includes at least one of the following beneficial technical effects:

[0049] 1. When the space above the light-emitting chip is limited, through the overlapping arrangement of the powder spraying process, the dispensing process and the powder spraying process, the uniform coating of the first phosphor layer, the second phosphor glue layer and the third phosphor glue layer is ensured, and the light transmittance is also ensured, avoiding the light being unable to emit due to the stacking of too thick high-density powder layers, and improving the light extraction efficiency of the COB light source;

[0050] 2. The first phosphor layer completely covers the light-emitting path of the light-emitting chip, eliminating the halo caused by light leakage;

[0051] 3. The light emitted by the light-emitting chip sequentially passes through the first phosphor layer, the second phosphor glue layer and the third phosphor layer, and the wavelength of the light excited by the phosphor is greater than the wavelength that the subsequent phosphor layer can absorb. Therefore, the loss of the excited light during propagation can be further reduced, and the light extraction intensity can be improved. BRIEF DESCRIPTION OF THE DRAWINGS

[0052] Figure 1 is a top view of a high-uniformity white light COB light source according to Embodiment 1 of the present application;

[0053] Figure 2 is along Figure 1 the cross-sectional view taken along line A-A in

[0054] Figure 3 is Figure 2 the partial enlarged view of area B in

[0055] Figure 4 is a schematic diagram of step B2 of a processing method of a high-uniformity white light COB light source according to Embodiment 2 of the present application;

[0056] Figure 5 is a schematic diagram of step B3 of a processing method of a high-uniformity white light COB light source according to Embodiment 2 of the present application;

[0057] Figure 6 is a schematic diagram of step B4 of a processing method of a high-uniformity white light COB light source according to Embodiment 2 of the present application;

[0058] Figure 7It is a schematic diagram of step B5 of a processing method for a high-uniformity white light COB light source according to Embodiment 2 of the present application;

[0059] Figure 8 It is a schematic diagram of step B6 of a processing method for a high-uniformity white light COB light source according to Embodiment 2 of the present application;

[0060] Figure 9 It is a schematic diagram of step B7 of a processing method for a high-uniformity white light COB light source according to Embodiment 2 of the present application;

[0061] Figure 10 It is a schematic diagram of step B8 of a processing method for a high-uniformity white light COB light source according to Embodiment 2 of the present application.

[0062] Explanation of reference numerals: 1, base; 11, support body; 12, pit; 121, reflection part; 122, dam part; 2, first encapsulation layer; 3, first phosphor layer; 4, second phosphor glue layer; 5, third phosphor layer; 6, second encapsulation layer; 7, light-emitting chip; 8, lamp holder; 9, pad. Detailed implementation manners

[0063] The following will Figure 1-10 make a further detailed description of the present application.

[0064] Currently, there are mainly two implementation methods for white light sources. One is that the mixed light of multiple color light chips shows white light. The other is to coat phosphors of other spectra on the surface of short-wavelength LED chips, especially blue LED chips. Part of the light emitted by the blue LED chips is absorbed by the phosphors and excites light of other colors. These excited lights are mixed with the unabsorbed blue light to show white light. In the actual application process, especially in the workpiece of powder spraying processing, because the amount of the bottom phosphor is small and it is difficult to coat the side light-emitting surface of the blue LED chip, the light emitted from the uncoated side light-emitting surface will remain in the light-emitting spot, forming an obvious blue halo and destroying the uniformity of the light emission; in the former, the multi-color light chips also rely on the excitation of the blue LED chip on the color phosphor. Otherwise, the driving voltages of the LED chips of different spectra have a large gap, and the combined use places a great pressure on the driving IC.

[0065] Therefore, how to solve the light leakage problem of the powder spraying processing technology and eliminate the short-wavelength halo in the light-emitting spot is of extremely important significance for improving the light-emitting uniformity of the white light source.

[0066] Embodiment 2 of the present application discloses a high-uniformity white light COB light source.

[0067] Embodiment 1

[0068] Refer to Figure 1 、Figure 2 The highly uniform white light COB light source includes a light-emitting area and positive and negative electrode pads 9 located on the sides of the light-emitting area. The light-emitting area is provided with a white light COB light source. The white light COB light source includes a base 1 and a light-emitting chip 7, as well as a first packaging layer 2, a phosphor layer and a second packaging layer 6 arranged layer by layer. The phosphor layer includes a first phosphor layer 3, a second phosphor glue layer 4, and a third phosphor layer 5 arranged layer by layer. The pad 9 is electrically connected to the light-emitting chip 7.

[0069] It is stipulated that in this embodiment, the light emitting side of the device is the upward direction, and the side away from the light emitting side is the downward direction.

[0070] In this embodiment, the white light COB light source and the soldering pad 9 are both arranged on the lamp holder 8. The lamp holder 8 is a square plate with a circular receiving hole in the middle. The inner diameter of the circular receiving hole matches the outer diameter of the base 1. The support body 11 is embedded in the circular receiving hole and the two are fixedly connected. The thickness of the support body 11 is less than the depth of the circular receiving hole. Two soldering pads 9 are arranged on the upper surface of the lamp holder 8 except for the circular receiving hole. The surface of the lamp holder 8 except for the circular receiving hole and the soldering pads 9 is coated with white paint.

[0071] It should be noted that the lamp holder 8 and the bracket in this embodiment can be designed as separate parts or integrally formed.

[0072] Please refer to Figure 3 The support seat includes a support body 11, which can be an aluminum plate or a highly reflective ceramic substrate. A plurality of pits 12 are provided on the surface of the support body 11, and the pits 12 are arranged in an array. The bottom surface of the pits 12 is circular. Except for the pits 12 located on the outermost circle, six pits 12 are arranged around each inner pit 12. In this way, the number of light-emitting chips 7 arranged in the light-emitting area can be increased, which is conducive to improving the chip density and is suitable for high-power and high-light-efficiency settings.

[0073] A reflective layer is provided on the inner wall of each pit 12. The center line of any three adjacent pits 12 forms an equilateral triangle, and there is a spacing greater than or equal to 100um between the edges of adjacent pits 12 to ensure structural stability, and the spacing is preferably 200um.

[0074] Preferably, the pit 12 includes a reflecting portion 121 for setting the chip and a dam portion 122 connected to the reflecting portion 121, and the diameter of the reflecting portion 121 gradually increases from the bottom to the dam portion 122; the diameter of the dam portion 122 is a constant value or the diameter of the dam portion 122 gradually decreases from the position connected to the reflecting portion 121 to the position away from the reflecting portion 121.

[0075] Further preferably, on the cross-section passing through the optical axis of any light-emitting chip 7, the inner wall of the corresponding reflecting portion 121 is a part of a parabola, and the light-emitting chip 7 is located at the focal position of the parabola; or, on the cross-section passing through the optical axis of any light-emitting chip 7, the included angle α between the inner wall of the corresponding reflecting portion 121 and the bottom of the pit 12 ranges from 130° to 140°.

[0076] Preferably, the reflective layer is mirror aluminum, and the reflectivity of white light is greater than or equal to 98%.

[0077] It should be noted that, for the consideration of processing efficiency, a preferred processing method is to use a drill bit with a frustum-shaped tip to synchronously process the reflecting portion 121 and the dam portion 122 of the pit 12 on the plate-shaped carrier 11, and then achieve the reflection effect of the inner wall of the pit 12 through polishing and PVD processes.

[0078] A light-emitting chip 7 is provided at the bottom of each pit 12. The light-emitting chip 7 is preferably a blue LED chip. The light-emitting chip 7 is electrically connected to two pads 9. Specifically, the light-emitting chip 7 is a flip-chip. After the light-emitting chips 7 are grouped and connected in series by gold wires, they are connected in parallel between the two pads 9. Exemplarily, a circuit layer is printed on the upper surface of the lamp holder 8, and electrodes corresponding to the pads 9 one by one are provided at the upper end of the side wall of the circular accommodating hole. The electrodes are electrically connected to the pads 9 through the circuit layer and are electrically connected to the light-emitting chip 7.

[0079] A first encapsulation layer 2 is filled around each light-emitting chip 7, and the first encapsulation layer 2 is transparent. In this embodiment, the first encapsulation layer 2 has the same thickness as the light-emitting chip 7, and the surface of the light-emitting chip 7 is flush with the first encapsulation layer 2 to achieve the effect of covering the side light-emitting surface of the light-emitting chip 7.

[0080] It should be noted that the setting of the first encapsulation layer 2 is to avoid light leakage from the side of the light-emitting chip 7 caused by the first phosphor layer 3 being too thin. The first encapsulation layer 2 raises the position where the first phosphor layer 3 is to be sprayed on the side of the light-emitting chip 7. Preferably, the first phosphor layer 3 can wrap the epitaxial layer and the electrode layer of the light-emitting chip 7.

[0081] Therefore, in other implementation schemes of this embodiment, the first encapsulation layer 2 can optionally completely wrap the light-emitting chip 7, or be slightly thinner than the light-emitting chip 7. For the latter case, the thickness of the first encapsulation layer 2 is slightly lower than the thickness of the light-emitting chip 7, and this thickness difference is between 18 - 25 um, preferably 20 um. After spraying the first phosphor layer 3, it is ensured that the first phosphor layer 3 and the first encapsulation layer 2 can jointly wrap the front light-emitting surface and the side light-emitting surface of the light-emitting chip 7. The surface of the first encapsulation layer 2 adjacent to the light-emitting side of the light-emitting chip 7 is a plane, so that light is more likely to be directly emitted without being reflected back.

[0082] The first phosphor layer 3 is sprayed on the upper surface of the first packaging layer 2 and the light-emitting chip 7, with a thickness greater than or equal to 20 um. The first phosphor doped in the first phosphor layer 3 radiates a first light after being excited by the blue light.

[0083] In order to first excite the long wavelength light emitted upward from the light emitting chip 7, the long wavelength fluorescence transmitted upward will no longer excite the phosphor with a shorter wavelength. In this embodiment, the surface of the first phosphor layer 3 is further provided with a second phosphor glue layer 4 and a third phosphor layer 5.

[0084] The second phosphor layer 4 is dotted in each pit 12 to cover the upper surface of the first phosphor layer 3, the edge of the upper surface of the second phosphor layer 4 is in contact with the edge of the pit 12, and the center of the upper surface of the second phosphor layer 4 is raised and higher than the upper surface of the support body 11. The second phosphor doped in the second phosphor layer 4 radiates the second light after being excited by the blue light.

[0085] The third phosphor layer 5 is sprayed on the upper surface of the second phosphor glue layer 4 and the upper surface of the support body 11 except the pit 12. The third phosphor doped in the third phosphor layer 5 radiates a third light after being excited by the blue light.

[0086] The first phosphor layer 3 and the third phosphor layer 5 are formed by spraying, and the mass ratio of the first phosphor or the third phosphor to the glue is between 1:1-10:1. The second phosphor glue layer 4 is prepared by dispensing, and the mass ratio of the second phosphor to the glue is between 1:5-1:1. The refractive index of the first phosphor layer 3, the second phosphor glue layer 4 and the third phosphor layer 5 is higher than that of the first packaging glue layer, and the preferred refractive index difference is greater than or equal to 0.2. The wavelength of the first light, the wavelength of the second light and the wavelength of the third light decrease in sequence. For example, the first light is red light, the second light is orange light, and the third light is yellow light.

[0087] A second encapsulation layer 6 is disposed on the side of the third phosphor layer 5 facing away from the light emitting chip 7 . The lower surface of the second encapsulation layer 6 is in contact with the upper surface of the third phosphor layer 5 . The upper surface of the second encapsulation layer 6 is flat and flush with the upper surface of the lamp holder 8 .

[0088] Of course, it can be understood that the number of phosphor layers is not limited to the three layers of the present embodiment, and there can be more settings, such as four types, and generally at most 4-5 types, because the color coordinates of too many types of phosphors are difficult to control, and the divergence will become very large. For the four types of phosphors, we first spray the powder with the longest wavelength, then mix the powder with the middle wavelength of the two powders in the glue, and finally spray the powder with the shortest wavelength.

[0089] In this embodiment, powder spraying is first performed, followed by dispensing, and then powder spraying again. Firstly, powder spraying is easier to control the thickness, thus enabling the overall control of the thickness of the entire phosphor layer. Secondly, powder spraying can increase the concentration of phosphors in the first phosphor layer 3 and the third phosphor layer 5, reducing the probability of side light leakage. Moreover, the phosphor glue layer covered in the middle layer is equivalent to introducing a colloidal interface with a refractive index change, which can improve the light extraction efficiency.

[0090] The implementation principle of Embodiment 1 is as follows:

[0091] The light-emitting chip 7 is powered on to work and emits original light. Among them, the light emitted from the positive light-emitting surface directly irradiates the first phosphor layer 3, and the light emitted from the side light-emitting surface irradiates the first phosphor layer 3 after passing through the first encapsulation layer 2, or irradiates the first phosphor layer 3 after passing through the propagation and reflection of the first encapsulation layer 2 and the reflection layer.

[0092] Inside the first phosphor layer 3, part of the original light penetrates the first phosphor layer 3 to reach the second phosphor glue layer 4, and the other part of the original light is absorbed by the first phosphor. Then, the first phosphor radiates the first red light, and the first light is directly or indirectly transmitted to the second phosphor glue layer 4.

[0093] Inside the second phosphor glue layer 4, because the wavelength of the first light is greater than the absorbable band of the second phosphor, the first light penetrates the second phosphor glue layer 4 to reach the third phosphor layer 5; part of the original light is absorbed by the second phosphor, and the second phosphor radiates the second orange light, and the second light and the unabsorbed original light are transmitted to the third phosphor layer 5 together.

[0094] Inside the third phosphor layer 5, because the wavelengths of the first light and the second light are greater than the absorbable band of the third phosphor, the first light and the second light penetrate the third phosphor layer 5 to reach the second encapsulation layer 6; part of the original light is absorbed by the third phosphor, and the third phosphor radiates the third yellow light, and the third light and the unabsorbed original light are transmitted to the second encapsulation layer 6 together.

[0095] Inside the second encapsulation layer 6, the blue original light, the red first light, the orange second light, and the yellow third light are mixed and emitted, presenting white light. Since the first phosphor layer 3 completely blocks the propagation path of the original light, there is no light leakage phenomenon in the light-emitting spot of this embodiment, and the light-emitting uniformity is greatly increased.

[0096] It should be noted that the process of stimulated emission of the phosphor does not have a directionality. Some of the light propagates towards the light-emitting direction at the point of radiation, while another part of the light will deviate from the light-emitting direction until it is reflected or refracted and then exits. Moreover, during the propagation of the light, when it irradiates on the surface of the phosphor, it is not necessarily absorbed, and there is also a situation of reflection. These reasons may lead to a decrease in the light extraction efficiency, which also exists in existing white light sources and is not a negative technical effect caused by the technical solution of this embodiment.

[0097] In addition, the above analysis only discusses the main situations of light propagation and excitation within each layer. In fact, there is also light reflection within each layer, causing the light to return from the upper layer to the adjacent lower layer; there are also reflection and refraction at the junctions of each layer. Refraction will change the propagation direction of the light, but will not change the nature of the light exiting.

[0098] The following analyzes the reflection of light.

[0099] Since the refractive indices of the first phosphor layer 3, the second phosphor glue layer 4, and the third phosphor layer 5 are higher than that of the first encapsulation glue, on the upper surface of the first encapsulation layer 2, the light incident from the first encapsulation layer 2 into the third phosphor layer 5 is unobstructed, while there is a probability of total reflection when the light is incident from the third phosphor layer 5 into the first encapsulation layer 2. This can reduce the probability of the light being reflected to the bottom of the pit 12, shorten the optical path, and increase the light extraction intensity.

[0100] The same situation also occurs on the lower surface of the second encapsulation layer 6. Due to the convex points on the upper surface of the second phosphor glue, the lower surface of the second encapsulation layer 6 is not parallel to the upper surface of the first encapsulation layer 2 and the bottom of the pit 12. After the light is reflected by the lower surface of the second encapsulation layer 6 and then reflected back to the lower surface of the second encapsulation layer 6 via other surfaces, the incident angle at this time is not the same as the incident angle when it first reaches the lower surface of the second encapsulation layer 6. If the new incident angle still does not meet the incident conditions of the second encapsulation layer 6, it will be reflected again until the conditions are met.

[0101] Between the first phosphor layer 3, the second phosphor glue layer 4, and the third phosphor layer 5, both the first phosphor layer 3 and the third phosphor layer 5 are processed by powder spraying, while the second phosphor glue layer 4 is made by dispensing. On the one hand, it avoids the high-density powder accumulation caused by continuous powder spraying, reduces the powder spraying accumulation thickness, and reduces the proportion of light that is reflected by the accumulated powder and cannot exit; on the other hand, it avoids the problems of insufficient single-layer thickness and uneven coating caused by multi-layer dispensing. In addition, although the concentration of the second phosphor in the second phosphor glue layer 4 is low, the thickness of the second phosphor layer is large, and there is a probability that the second phosphor layer will be reflected back whether it is incident on the first phosphor layer 3 or the third phosphor layer 5. Therefore, in the finally emitted white light, the situation where the proportion of the second light is too small will not occur.

[0102] Exemplarily, the concentration of the first phosphor in the first phosphor layer 3 is greater than the concentration of the third phosphor in the third phosphor layer 5, which can further reduce the negative impact of the third phosphor layer 5 on the light extraction efficiency and improve the light extraction intensity.

[0103] Example 2

[0104] The difference between this embodiment and Example 1 is that: the first encapsulation layer 2 in this embodiment is doped with light diffusing spheres for scattering the light irradiated on the surface of the light diffusing spheres in all directions.

[0105] Preferably, the concentration of the light diffusing spheres increases from the light-emitting chip 7 towards the inner wall of the pit 12.

[0106] The implementation principle of Example 2 is as follows:

[0107] When the light exits from the side light-emitting surface of the light-emitting chip 7, it propagates in the first encapsulation layer 2, and the propagation directions of most of the light are perpendicular to the light exit direction until the propagation direction is changed after being scattered by the light diffusing spheres and then directly exits or exits after reflection. The intensity of the light decreases from the light-emitting chip 7 towards the inner wall of the pit 12, and the concentration of the light diffusing spheres increases from the light-emitting chip 7 towards the inner wall of the pit 12. That is, the probability of the light being scattered and exiting increases, making the light have a relatively uniform intensity on the upper surface of the entire first encapsulation layer 2.

[0108] The embodiments of the present application also disclose a processing method for a high-uniformity white light COB light source.

[0109] Example 3

[0110] The processing method for a high-uniformity white light COB light source includes the following steps:

[0111] B1. Provide a lamp holder 8 and a base 1 disposed on the lamp holder 8, and two pads 9 are provided on the lamp holder 8.

[0112] Exemplarily, the base 1 is an aluminum circular plate.

[0113] B2. Refer to Figure 4 , and form pits 12 arranged in an array on one side of the base 1.

[0114] Exemplarily, the pits 12 are cylindrical, and the connection lines of the centers of three adjacent pits 12 form an equilateral triangle. The bottom and side walls of the pits 12 are provided with a reflective layer, and the reflective layer is preferably mirror aluminum.

[0115] Optionally, a reflective cup as in Example 1 is provided at the bottom of the pit 12.

[0116] B3. Refer to Figure 5A light emitting chip 7 is arranged at the bottom of each pit 12 in a one-to-one correspondence, and the pad 9 is electrically connected to the light emitting chip 7 .

[0117] Exemplarily, the light emitting chip 7 is a blue light LED chip, and the light emitting chip 7 is located at the center of the bottom surface of the pit 12 .

[0118] B4. Reference Figure 6 , the packaging glue is filled around the light emitting chip 7 to form a first packaging layer 2.

[0119] Exemplarily, the upper surface of the first encapsulation layer 2 is flush with the upper surface of the light emitting chip 7 .

[0120] B5. Reference Figure 7 The phosphor glue is sprayed on the surface of the first packaging layer 2 and the light-emitting chip 7 to form a first phosphor layer 3 .

[0121] It should be noted that, due to the limitation of the processing technology, part of the first phosphor may remain on the surface of the support body 11 between adjacent pits 12 . This part of the first phosphor is preferably removed before the second phosphor glue layer 4 is applied.

[0122] B6. Reference Figure 8 A second phosphor glue layer 4 is prepared by dispensing glue on the side of the first phosphor layer 3 away from the light-emitting chip 7 , the edge of the second phosphor glue layer 4 in each pit 12 is flush with the edge of the pit 12 , and the center of the second phosphor glue layer 4 bulges higher than the base 1 .

[0123] It should be noted that, referring to the description in Example 1, the purpose of the protrusion on the upper surface of the second phosphor glue layer 4 is to avoid the appearance of two relative parallel reflective surfaces. In other implementation schemes of this embodiment, the upper surface of the second phosphor glue layer 4 can also be concave. In this case, it can also have a divergent effect on the light, so that the brightness of the light-free area between the pits 12 is increased, and the light output effect is more uniform.

[0124] B7, Reference Figure 9 The phosphor glue is sprayed on the surface of the base 1 between the second phosphor glue layer 4 and the adjacent pits 12 to form a third phosphor layer 5 .

[0125] Exemplarily, the wavelengths of the light emitted by the first phosphor layer 3 , the second phosphor glue layer 4 , and the third phosphor layer 5 under stimulated radiation decrease in sequence.

[0126] Optionally, if more colors of phosphors need to be added, the color with the longest wavelength is selected to process the first phosphor layer 3, and the color with the shortest wavelength is selected to process the third phosphor layer 5. The remaining colors of phosphors are mixed and evenly distributed in the second phosphor glue layer 4. The total number of colors of phosphors is preferably less than or equal to five.

[0127] B8. Refer to Figure 10 , on the side of the third phosphor layer 5 away from the light-emitting chip 7, an encapsulant is coated to form a second encapsulation layer 6, and the surface of the second encapsulation layer 6 away from the light-emitting chip 7 is a plane.

[0128] It should be noted that the processing step sequence provided in this embodiment is only a preferred embodiment, and the technical solutions obtained by swapping the steps according to the principle of this application are also within the protection scope of this application.

[0129] The implementation principle of Embodiment 3 is as follows:

[0130] Similar to Embodiment 1, the original light emitted by the light-emitting chip 7 sequentially passes through the first phosphor layer 3, the second phosphor glue layer 4, and the third phosphor layer 5. In each layer, part of the original light is absorbed and correspondingly excites the first light, the second light, and the third light. The red first light, the orange second light, the yellow third light, and the unabsorbed part of the blue original light are mixed and emitted, presenting as white light.

[0131] For the current COB light source processing technology, the thickness of the phosphor glue coated on the light-emitting chip 7 is only several hundred micrometers. In this case, if three layers of phosphor glue are to be stacked, if dispensing or scraping coating is used, it will be difficult to coat evenly due to the insufficient thickness of a single layer; if three-layer powder spraying is used, the light will be difficult to emit due to the too small powder spacing and too large stacking thickness. Therefore, this embodiment selects a three-layer structure of spraying - dispensing - spraying. The first phosphor layer 3 and the third phosphor layer 5 are prepared by powder spraying process to achieve the effect of saving thickness, while the second phosphor glue layer 4 ensures the smooth propagation of light with a smaller powder density.

[0132] Embodiment 4

[0133] The difference between this embodiment and Embodiment 3 is as follows:

[0134] Step B4 of this embodiment includes:

[0135] Mix light diffusing spheres in silicone rubber or silicone resin to obtain an encapsulant;

[0136] Coat the encapsulant on the surface of the base 1 around the light-emitting chip 7 and between adjacent pits 12;

[0137] Let it stand and wait for the encapsulant on the surface of the base 1 between adjacent pits 12 to flow down along the inner wall of the pits 12;

[0138] Cure the encapsulant to obtain the first encapsulation layer 2.

[0139] Preferably, after the encapsulant is cured, the residual encapsulant outside the pits 12 is removed.

[0140] The implementation principle of Embodiment 4 is as follows:

[0141] The encapsulation glue contains light diffusion spherules with a relatively large density and organosilicon glue or silicone resin with a relatively small density and strong fluidity. During the process of standing still and waiting for the encapsulation glue to flow downward, the light diffusion spherules with a relatively large density will settle downward. Therefore, this part of the flowing encapsulation glue will contain more light diffusion spherules at the position close to the side wall of the pit 12, while near the light-emitting chip 7, the concentration of the light diffusion spherules decreases. That is to say, during the dispensing process of the same encapsulation glue, the first encapsulation layer 2 at the near-light end has a weaker divergence ability, and the first encapsulation layer 2 at the far-light end has a stronger divergence ability, so that the upper surface of the entire first encapsulation layer 2 has a relatively uniform light intensity.

[0142] It should be noted that the processing technology of this embodiment will inevitably result in a higher concentration of light diffusion spherules below the first encapsulation layer 2. This phenomenon can be compensated by appropriately increasing the thickness of the first encapsulation layer 2, so that even if some light diffusion spherules settle to the bottom of the first encapsulation layer 2, the effective light diffusion spherules actually participating in light regulation will not decrease.

[0143] The above are all the preferred embodiments of the present application, and the protection scope of the present application is not limited accordingly. Therefore, all equivalent changes made according to the structure, shape, and principle of the present application shall be covered within the protection scope of the present application.

Claims

1. A highly uniform white light COB light source, characterized in that: include: A base (1), the base (1) comprising a base body (11) and an array of recessed holes (12) formed on a surface of one side of the base body (11); Light-emitting chips (7), the light-emitting chips (7) being arranged in a one-to-one correspondence at the bottom of the pit (12); A first packaging layer (2) is filled in the bottom of the pit (12) and at least wraps a portion of the side light emitting surface of the light emitting chip (7); A phosphor layer, the phosphor layer being arranged on the surface of the first encapsulation layer (2), the first encapsulation layer (2) and the phosphor layer jointly wrapping the front light emitting surface and the side light emitting surface of the light emitting chip (7); wherein the phosphor layer comprises: a first phosphor layer (3), the first phosphor layer (3) being sprayed on a side of the first encapsulation layer (2) away from the bottom of the pit (12), and the first phosphor layer (3) and the first encapsulation layer (2) together wrapping a front light emitting surface and a side light emitting surface of the light emitting chip (7); A second phosphor glue layer (4), wherein the second phosphor glue layer (4) is glued into the recess (12); A third phosphor layer (5), the third phosphor layer (5) being sprayed on the side of the second phosphor glue layer (4) facing away from the first phosphor layer (3), covering the upper surface of the second phosphor glue layer (4) and the surface of the support body (11) between adjacent pits (12); the mass ratio of the first phosphor included in the first phosphor layer (3) to the glue liquid is between 1:1-10:1, the mass ratio of the third phosphor included in the third phosphor layer (5) to the glue liquid is between 1:1-10:1, the mass ratio of the second phosphor included in the second phosphor glue layer (4) to the glue liquid is between 1:5-1:1, and the first phosphor The thickness of the first phosphor layer (3) and the thickness of the third phosphor layer (5) are respectively less than the thickness of the second phosphor glue layer (4); the upper surface of the edge of the second phosphor glue layer (4) is flush with the upper surface of the support body (11); the middle protrusion of the second phosphor glue layer (4) is higher than the surface of the support body (11); the refractive index of the first phosphor layer (3), the second phosphor glue layer (4) and the third phosphor layer (5) are all higher than that of the first encapsulation layer (2); and the difference between the refractive index of the first phosphor layer (3), the second phosphor glue layer (4) and the third phosphor layer (5) and the refractive index of the first encapsulation layer (2) is greater than or equal to 0.2; and A second encapsulation layer (6), the second encapsulation layer (6) covers a surface of the phosphor layer on a side facing away from the light-emitting chip (7).

2. The highly uniform white light COB light source according to claim 1, characterized in that: The pit (12) comprises a reflective portion (121) on which the chip is arranged and a dam portion (122) connected to the reflective portion (121), wherein the diameter of the reflective portion (121) gradually increases from the bottom toward the dam portion (122); The diameter of the dam portion (122) is a constant value, or the diameter of the dam portion (122) gradually decreases from a position connected to the reflection portion (121) to a position away from the reflection portion (121).

3. The highly uniform white light COB light source according to claim 2, characterized in that: In a cross section passing through the optical axis of any of the light-emitting chips (7), the inner wall of the corresponding reflective portion (121) is a part of a parabola, and the light-emitting chip (7) is located at the focal position of the parabola; Alternatively, in a cross section passing through the optical axis of any of the light-emitting chips (7), the inner wall of the corresponding reflective portion (121) and the bottom of the pit (12) are spaced at an angle of 130°-140°.

4. The highly uniform white light COB light source according to claim 1, characterized in that: A surface of the second encapsulation layer (6) that is away from the light-emitting chip (7) is a plane.

5. The highly uniform white light COB light source according to claim 1, characterized in that: The first packaging layer (2) is doped with light diffusion spherical particles, which are used to make light propagate in all directions within the first packaging layer (2); The concentration of the light diffusion spherical particles increases gradually from the light emitting chip (7) to the inner wall of the pit (12).

6. The highly uniform white light COB light source according to claim 1, characterized in that: The powder concentration in the first phosphor layer (3) is greater than the powder concentration in the third phosphor layer (5); and / or After being excited, the wavelengths of light emitted by the first phosphor layer (3), the second phosphor glue layer (4) and the third phosphor layer (5) decrease in sequence.

7. A method for processing a highly uniform white light COB light source, characterized in that: The following steps are involved: B1. Providing a lamp stand (8) and a base (1) disposed on the lamp stand (8); B2, providing an array of recessed holes (12) on one side of the base (1), so that the base (1) comprises a support body (11) and the recessed holes (12) provided in an array on a surface of one side of the support body (11); B3. Arranging light-emitting chips (7) at the bottom of each of the pits (12) in a one-to-one correspondence; B4, filling the surroundings of the light-emitting chip (7) with packaging glue to form a first packaging layer (2); B5. Processing a phosphor layer on the surface of the first packaging layer (2) and the light-emitting chip (7), wherein step B5 comprises: Spraying phosphor glue on the surface of the first packaging layer (2) and the light-emitting chip (7) to form a first phosphor layer (3); A second phosphor glue layer (4) is prepared by dispensing glue on a side of the first phosphor layer (3) facing away from the light-emitting chip (7), wherein the center of the second phosphor glue layer (4) is bulged and higher than the base (1); A phosphor glue is sprayed on the surface of the base (1) between the second phosphor glue layer (4) and the adjacent pits (12) to form a third phosphor layer (5), and the third phosphor layer (5) covers the upper surface of the second phosphor glue layer (4) and the surface of the base (11) between the adjacent pits (12); the mass ratio of the first phosphor included in the first phosphor layer (3) to the glue liquid is between 1:1-10:1, the mass ratio of the third phosphor included in the third phosphor layer (5) to the glue liquid is between 1:1-10:1, the mass ratio of the second phosphor included in the second phosphor glue layer (4) to the glue liquid is between 1:5-1:1, and the mass ratio of the third phosphor included in the third phosphor layer (5) to the glue liquid is between 1:1-10:

1. The thickness of the first phosphor layer (3) and the thickness of the third phosphor layer (5) are respectively smaller than the thickness of the second phosphor glue layer (4); the upper surface of the edge of the second phosphor glue layer (4) is flush with the upper surface of the support body (11); the middle part of the second phosphor glue layer (4) is raised and higher than the surface of the support body (11); the refractive index of the first phosphor layer (3), the second phosphor glue layer (4) and the third phosphor layer (5) is higher than that of the first encapsulation layer (2); and the difference between the refractive index of the first phosphor layer (3), the second phosphor glue layer (4) and the third phosphor layer (5) and the refractive index of the first encapsulation layer (2) is greater than or equal to 0.2; B6. Coating a packaging adhesive on the side of the phosphor layer facing away from the light-emitting chip (7) to form a second packaging layer (6), wherein the surface of the second packaging layer (6) on the side facing away from the light-emitting chip (7) is a plane.

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