Light-emitting device

Abstract

The utility model relates to the technical field of semiconductor luminescence, and discloses a luminescent device, which comprises a substrate, a luminescent chip, a first fluorescent glue layer and a second fluorescent glue layer. The light-emitting chip is arranged on the substrate. The first fluorescent glue layer at least covers the upper surface of the light-emitting chip. And first fluorescent particles are arranged in the first fluorescent glue layer. The second fluorescent glue layer at least covers the upper surface of the first fluorescent glue layer, and second fluorescent particles are arranged in the second fluorescent glue layer. The heat conductivity of the first fluorescent glue layer is greater than that of the second fluorescent glue layer. The two fluorescent glue layers with different thermal conductivities are arranged, so that the problem of poor thermal conductivity of the fluorescent glue layers can be solved, the temperature of the fluorescent glue layers is reduced, and glue cracks are effectively avoided; meanwhile, the consistency of light emitting color and brightness is better, and the product quality and reliability are greatly improved; the product is easier to manufacture, and the yield is greatly improved.

Description

TECHNICAL FIELD

[0001] The utility model belongs to the technical field of semiconductor light emitting, and particularly relates to a light emitting device. BACKGROUND

[0002] The prior art light emitting device covers a fluorescent glue layer, and there are usually two methods:

[0003] The prior art first method is bonding. The fluorescent glue layer is pre-formed, and then the fluorescent glue layer is pasted to the upper surface of the light emitting chip through adhesive. Referring to Figure 5 , the light emitting device comprises, from bottom to top, a substrate 1, a light emitting chip 2, an adhesive layer 4 and a fluorescent glue layer 3.

[0004] The problem is that the heat generated by the light-excited fluorescent particles in the fluorescent glue layer 3 needs to be conducted downward, but the adhesive layer 4 has poor thermal conductivity, so that the heat in the fluorescent glue layer 3 cannot be well conducted out, and the fluorescent glue layer 3 cracks due to high temperature, reducing the product yield.

[0005] The prior art second method is a mold pressing process. The fluorescent glue is directly pressed to the upper surface of the light emitting chip by using a mold, and the mold is removed after solidification and molding, so that the fluorescent glue layer is formed on the light emitting chip. Referring to Figure 6 , the light emitting device comprises, from bottom to top, a substrate 1, a light emitting chip 2 and a fluorescent glue layer 3.

[0006] The problem is that (1) the concentration of the fluorescent particles in the fluorescent glue layer 3 affects the heat conduction. When other conditions are constant, the fluorescent glue layer 3 with high concentration of fluorescent particles has better thermal conductivity than the fluorescent glue layer 3 with low concentration of fluorescent particles. When the same total amount of fluorescent particles is excited by light, the fluorescent glue layer 3 with low concentration has a thick glue layer, small error rate of glue layer thickness and is easy to manufacture, but has poor heat conduction; the fluorescent glue layer 3 with high concentration has a thin glue layer, good heat conduction, but has a large error rate and high manufacturing precision, and low yield. Of course, the heat conduction performance can also be improved by adding other heat-conducting particles to the fluorescent glue layer 3 with low concentration, but this will affect the light brightness on the one hand, and the flowability of the fluorescent glue will be poor, increasing the manufacturing difficulty. (2) The thickness of the incoming light emitting chip 2 has an error, and the thickness cannot be completely consistent, while the mold pressing height is consistent, so that the thickness of the formed fluorescent glue layer 3 is different, the color of the light after the light passes through the fluorescent glue layer 3 is inconsistent, the light emitting device is displayed, the light color is not uniform, and the product quality is low.

[0007] Based on the above, the current problem to be solved is to provide a light emitting device with good heat conduction performance, consistent light color and brightness, easy to manufacture and high product yield. Utility model content

[0008] The utility model discloses a light emitting device, which aims to solve the problem of cracking of the fluorescent glue layer of the light emitting device due to poor heat conduction performance, inconsistent light color and brightness, high manufacturing precision and low product yield in the prior art.

[0009] The utility model discloses a light emitting device, which aims to solve the problem of cracking of the fluorescent glue layer of the light emitting device due to poor heat conduction performance, inconsistent light color and brightness, high manufacturing precision and low product yield in the prior art.

[0010] A substrate;

[0011] A light emitting chip is arranged on the substrate;

[0012] A first fluorescent glue layer covers at least the upper surface of the light emitting chip, and first fluorescent particles are arranged in the first fluorescent glue layer;

[0013] A second fluorescent glue layer covers at least part of the upper surface of the first fluorescent glue layer, and second fluorescent particles are arranged in the second fluorescent glue layer;

[0014] The thermal conductivity of the first fluorescent glue layer is greater than that of the second fluorescent glue layer.

[0015] Further, the first fluorescent particles and the second fluorescent particles are the same kind of fluorescent particles, the concentration of the first fluorescent particles is C1, the concentration of the second fluorescent particles is C2, and C2 < C1 is satisfied.

[0016] Further, C1 and C2 satisfy C2 / C1 ≤ 0.5.

[0017] Further, the first fluorescent particles and the second fluorescent particles are different kinds of fluorescent particles, and the thermal conductivity of the first fluorescent particles is greater than that of the second fluorescent particles.

[0018] Further, the second fluorescent particles include the first fluorescent particles and fluorescent particles with a lower thermal conductivity than the first fluorescent particles, the concentration of the first fluorescent particles is C1, the concentration of the second fluorescent particles is C2, and C2 ≤ C1 is satisfied.

[0019] Further, the thickness of the first fluorescent glue layer 31 is 35-120 um.

[0020] Further, the thickness of the first fluorescent glue layer is less than that of the second fluorescent glue layer.

[0021] Further, the side surface of the first fluorescent glue layer is provided with a reflection surface in the shape of an inverted cone.

[0022] Further, the periphery of the upper surface of the first fluorescent glue layer is provided with a protruding structure extending towards the second fluorescent glue layer, and the height of the upper surface of the protruding structure gradually increases in a direction away from the optical axis.

[0023] Further, the first fluorescent glue layer is provided with an extension part extending to the outside of the four sides of the light emitting chip, and the extension part is used for accumulating the excess first fluorescent glue; a part of the upper surface of the first fluorescent glue layer is covered by the second fluorescent glue layer, and another part of the upper surface of the first fluorescent glue layer is covered by the high-reflection glue layer, so as to form a light emitting surface with a preset shape.

[0024] Compared with the prior art, the light emitting device has the following beneficial effects:

[0025] The first fluorescent glue layer 31 and the second fluorescent glue layer 32 are arranged in the utility model, the light emitting chip 2 generates a large amount of heat, and part of the heat generated by the light excited fluorescent particles is conducted to the light emitting chip 2 through the first fluorescent glue layer 31, the first fluorescent glue layer 31 has high thermal conductivity and good heat conduction performance, so that the glue cracking can be effectively avoided, and the small part of the heat generated by the light excited fluorescent particles in the second fluorescent glue layer 32 is conducted to the light emitting chip 2 through the first fluorescent glue layer 31, so that the influence on the quality of the product is small.

[0026] Meanwhile, the second fluorescent glue layer 32 with different concentrations can compensate for the thickness difference of the light emitting chip 2, the thickness error of the manufacturing precision of the first fluorescent glue layer 31, and the light emitting wavelength difference and the brightness difference, so that the color area can be well compensated, and the product yield can be improved. BRIEF DESCRIPTION OF DRAWINGS

[0027] Figure 1 is a cross-sectional structure schematic view of the light emitting device provided by the utility model;

[0028] Figure 2 is a cross-sectional structure schematic view of another light emitting device provided by the utility model;

[0029] Figure 3 is a cross-sectional structure schematic view of the combination of the light emitting chip, the first fluorescent glue layer, the second fluorescent glue layer and the high-reflection glue layer in the first embodiment provided by the utility model;

[0030] Figure 4 is a cross-sectional structure schematic view of the combination of the light emitting chip, the first fluorescent glue layer, the second fluorescent glue layer and the high-reflection glue layer in the second embodiment provided by the utility model;

[0031] Figure 5 is a cross-sectional structure schematic view of the light emitting device provided by the prior art;

[0032] Figure 6is a cross-sectional structure diagram of a light emitting device provided by the prior art two;

[0033] In the figure: 1 - substrate; 2 - light emitting chip; 3 - fluorescent glue layer; 31 - first fluorescent glue layer; 311 - reflecting surface; 312 - convex structure; 313 - extension; 32 - second fluorescent glue layer; 4 - adhesive layer; 5 - gold wire; 6 - high reflection glue layer; Z - optical axis. DETAILED DESCRIPTION

[0034] In order to make the purpose, technical scheme and advantages of the utility model clearer and more apparent, the utility model is further described in detail below in combination with the drawings and examples. It should be understood that the specific examples described herein are only used to explain the utility model and not to limit the utility model.

[0035] The implementation of the utility model is described in detail below in combination with specific examples.

[0036] In the drawings of the present embodiment, the same or similar reference numerals correspond to the same or similar components; in the description of the present utility model, it should be understood that if the orientations or positional relationships indicated by the terms "upper", "lower", "left", "right" and the like are based on the orientations or positional relationships shown in the drawings, they are only for the convenience of describing the utility model and simplifying the description, and do not indicate or imply that the devices or elements referred to must have a particular orientation, be constructed in a particular orientation and be operated, therefore the terms describing the positional relationships in the drawings are only used for exemplary illustration and cannot be understood as limiting the present patent, and for those skilled in the art, the specific meanings of the above terms can be understood according to the specific circumstances.

[0037] Referring to Figures 1-6 , a preferred embodiment provided by the utility model is shown.

[0038] The light emitting device comprises a substrate 1, a light emitting chip 2, a first fluorescent glue layer 31 and a second fluorescent glue layer 32, referring to Figure 1 . The light emitting device further comprises a gold wire 5 for electrically connecting the substrate 1 and the light emitting chip 2. The light emitting chip 2 is arranged on the substrate 1. The first fluorescent glue layer 31 covers at least the upper surface of the light emitting chip 2, and first fluorescent particles are arranged in the first fluorescent glue layer 31. That is, the first fluorescent glue layer 31 only covers the upper surface of the light emitting chip 2, or covers the upper surface and the side surface of the light emitting chip 2. The second fluorescent glue layer 32 covers at least part of the upper surface of the first fluorescent glue layer 31, and second fluorescent particles are arranged in the second fluorescent glue layer 32. That is, the second fluorescent glue layer 31 only covers part or all of the upper surface of the first fluorescent glue layer 31, or covers the upper surface and the side surface of the first fluorescent glue layer 31. The thermal conductivity of the first fluorescent glue layer 31 is greater than that of the second fluorescent glue layer 32.

[0039] The first fluorescent glue layer 31 solves the heat conduction problem, and the second fluorescent glue layer 32 is used for compensating the thickness difference of the first fluorescent glue layer 31, and the thickness, wavelength and brightness difference of the light emitting chip 2. Specifically, the first fluorescent glue layer 31 has large thermal conductivity and thin thickness, and has a large error rate in production. The second fluorescent glue layer 32 can compensate the thickness difference of the first fluorescent glue layer 31, that is, the first fluorescent glue layer 31 is allowed to have errors within a certain range, so that the forming precision of the first fluorescent glue layer 31 can be reduced, and the productivity and yield can be improved. At the same time, the second fluorescent glue layer 32 with different concentrations can compensate the thickness difference of the light emitting chip 2, the thickness error of the first fluorescent glue layer 31, and the light emitting wavelength difference and brightness difference, and can well compensate the color area.

[0040] Most of the heat generated by the light excitation of the first fluorescent particles is conducted to the light emitting chip 2 by the first fluorescent glue layer 31, and the heat conduction efficiency is high. On the one hand, the second fluorescent glue layer 32 compensates the thickness, wavelength and brightness problems caused by the light emitting chip 2 and the first fluorescent glue layer 31. On the other hand, a small part of the heat generated by the light excitation of the second fluorescent particles in the second fluorescent glue layer 32 is conducted to the light emitting chip 2 through the first fluorescent glue layer 31. Although the thermal conductivity of the second fluorescent glue layer 32 is lower than that of the first fluorescent glue layer 31, the heat is small, so the influence on the quality of the product is small. The heat conductivity of the double fluorescent glue layer structure in the utility model is good, which can effectively prevent the fluorescent glue layer from cracking due to heat; at the same time, the light emitting color and brightness of the light emitting device are consistent, and the quality and reliability of the product are improved. The product has low manufacturing precision and high yield.

[0041] The first fluorescent particles are arranged in the first fluorescent glue layer 31, and the second fluorescent particles are arranged in the second fluorescent glue layer 32, and the specific arrangement mode includes but is not limited to the following modes:

[0042] Mode one: the first fluorescent particles and the second fluorescent particles are the same kind of fluorescent particles, the concentration of the first fluorescent particles is C1, the concentration of the second fluorescent particles is C2, and C2 < C1 is satisfied. Preferably, C1 and C2 satisfy C2 / C1 ≤ 0.5.

[0043] Mode two: the first fluorescent particles and the second fluorescent particles are different kinds of fluorescent particles, and the thermal conductivity of the first fluorescent particles is greater than that of the second fluorescent particles.

[0044] Mode three: the second fluorescent particles are a mixture of multiple fluorescent particles. The second fluorescent particles include the first fluorescent particles and fluorescent particles with lower thermal conductivity than the first fluorescent particles, which can effectively improve the heat conduction performance of the second fluorescent glue layer 32. The concentration of the first fluorescent particles is C1, the concentration of the second fluorescent particles is C2, and C2 ≤ C1 is satisfied.

[0045] Optimization scheme: the preferred thickness range of the first fluorescent glue layer 31 is 35-120 um. Further, the thickness of the first fluorescent glue layer 31 is less than or equal to the thickness of the second fluorescent glue layer 32.

[0046] To improve the utilization rate of light energy, the side surface of the first fluorescent glue layer 31 is provided with an inverted conical reflecting surface 311, which is used to reflect the large-angle light around the edge to the direction close to the optical axis Z, thereby improving the utilization rate of light energy and the brightness. Figure 2

[0047] When the thickness of the incoming light-emitting chip 2 has a positive deviation, that is, the height of the chip is higher, the first fluorescent glue layer 31 is molded, and the first fluorescent glue is excessive, which may affect the shape of the light-emitting surface and the thickness of the glue layer. In view of the above situation, the second fluorescent glue layer 32 with corresponding concentration and second particles is used for compensation, and the structure is further optimized, as described in the following embodiments.

[0048] Embodiment one: the upper surface of the first fluorescent glue layer 31 is provided with a protruding structure 312 extending to the direction of the second fluorescent glue layer 32, as shown in Figure 3 . The upper surface of the protruding structure 312 is an inclined curved surface or a plane. The height (i.e. the straight-line distance) from the upper surface of the protruding structure 312 to the upper surface of the light-emitting chip 2 gradually increases in the direction away from the optical axis Z. The periphery of the mold for molding the first fluorescent glue layer 31 is made into an inclined surface matching the protruding structure 312. When the first fluorescent glue is pressed onto the light-emitting chip 2 by the mold, the first fluorescent glue at the periphery will extend upward along the inclined surface of the mold, which is beneficial to achieve the preset light-emitting surface shape and glue layer thickness. The side surface of the first fluorescent glue layer 31 and the second fluorescent glue layer 32 can be provided with a high-reflection glue layer 6, which covers the side surface of the first fluorescent glue layer 31 and the second fluorescent glue layer 32, cuts off the side light, and reflects the light to the upper surface of the first fluorescent glue layer 31 and the second fluorescent glue layer 32, thereby improving the utilization rate of light energy.

[0049] Embodiment two: the upper surface of the first fluorescent glue layer 31 extends to the outside of the light-emitting chip 2 to form an extension 313, as shown in Figure 4 . Therefore, the upper surface of the first fluorescent glue layer 31 is larger than the upper surface of the light-emitting chip 2. When the first fluorescent glue layer 31 cannot meet the preset light-emitting surface shape, the second fluorescent glue layer 32 can be used to achieve the preset shape of the light-emitting surface. Preferably, part of the upper surface of the first fluorescent glue layer 31 is covered by the second fluorescent glue layer 32, and another part of the upper surface is covered by the high-reflection glue layer 6. The light-emitting surface of the second fluorescent glue layer 32 can be provided with a circular, rectangular or other shaped light-emitting surface. The high-reflection glue layer 6 is used to shield the area outside the preset shape of the light-emitting surface, thereby achieving precise light control. The high-reflection glue layer 6 can also be provided to cover the side surface of the first fluorescent glue layer 31 and the light-emitting chip 2, thereby achieving the effect of cutting off the side light. ​

[0050] Without limiting the present application, any modification, equivalent replacement and improvement, etc. made within the spirit and principle of the present application shall be included in the protection scope of the present application.

Claims

1. A light emitting device, characterized by, The application relates to a light-emitting chip and a manufacturing method thereof. The application comprises: a substrate (1); a light-emitting chip (2) arranged on the substrate (1); a first fluorescent glue layer (31) covering at least the upper surface of the light-emitting chip (2), wherein the first fluorescent glue layer (31) is provided with first fluorescent particles; a second fluorescent glue layer (32) covering at least part of the upper surface of the first fluorescent glue layer (31), wherein the second fluorescent glue layer (32) is provided with second fluorescent particles; 2. The light emitting device of claim 1, wherein, the thermal conductivity of the first fluorescent glue layer (31) is greater than that of the second fluorescent glue layer (32).

3. The light emitting device of claim 1, wherein, The first fluorescent particles and the second fluorescent particles are different kinds of fluorescent particles, and the thermal conductivity of the first fluorescent particles is greater than that of the second fluorescent particles.

4. The light emitting device of claim 1, wherein, The thickness of the first fluorescent glue layer (31) is 35-120 um.

5. The light emitting device of claim 1, wherein, The thickness of the first fluorescent glue layer (31) is less than or equal to that of the second fluorescent glue layer (32).

6. The light emitting device of claim 1, wherein The side surface of the first fluorescent glue layer (31) is provided with an inverted conical reflecting surface (311).

7. The light emitting device of claim 1, wherein The upper surface of the first fluorescent glue layer (31) is provided with a convex structure (312) extending towards the second fluorescent glue layer (32), and the height of the upper surface of the convex structure (312) gradually increases in the direction away from the optical axis (Z). The four peripheral edges of the first fluorescent glue layer (31) are provided with extension parts (313) extending to the outside of the four peripheries of the light-emitting chip (2), and the extension parts (313) are used for accumulating excess first fluorescent glue; part of the upper surface of the first fluorescent glue layer (31) is covered by the second fluorescent glue layer (32), and the other part of the upper surface is covered by a high-reflection glue layer (6) for forming a light-emitting surface with a preset shape.

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