Red light emitting module and preparation method thereof

Abstract

The present invention discloses a red light emitting module and a preparation method thereof, wherein the preparation method comprises providing a high thermal conductivity substrate; mixing a first low-melting point glass powder with inorganic diffuse reflection particles, coating the mixture on the high thermal conductivity substrate, and then sintering the mixture to form a diffuse reflection layer; mixing an inorganic slurry formed by mixing a second low-melting point glass powder with a nitride red powder, coating the mixture on the diffuse reflection layer, and then sintering the mixture to form a red light glass layer, wherein the proportion of the nitride red powder in the inorganic slurry is not less than 25%; wherein the viscosity flow temperature of the second low-melting point glass powder is less than 600°C, the sintering temperature of the second low-melting point glass powder is less than 600°C, and the thermal expansion coefficient of the second low-melting point glass powder is less than 10*10 ‑6 / K. Through the above method, the red light emitting module prepared by the present invention has higher excitation efficiency.

Description

Technical Field

[0001] The invention relates to the field of lasers, and in particular to a red light emitting module and a preparation method thereof. Background Art

[0002] In the existing remote excitation phosphor technology, red phosphor has become a technical bottleneck in the field of laser display due to the serious thermal quenching problem. In low-power excitation light and low-brightness products, silica gel packaging is mainly used; but in high-power excitation light sources and high-brightness products, it can only be obtained by modifying and filtering the emission light of yellow phosphor with a longer wavelength; however, with the development of laser projection products, products are required to be upgraded in the direction of small size, high brightness and high efficiency. This means that the size of the wavelength conversion device inside is getting smaller and smaller, and the laser power density borne by its light-emitting layer is getting larger and larger, which requires higher heat resistance and thermal conductivity of the entire fluorescent material layer after encapsulation; the most prominent of these is the red fluorescent layer, which has the most serious thermal quenching phenomenon and the most prominent thermal effect, resulting in low laser excitation efficiency. Summary of the invention

[0003] The present invention provides a red light emitting module and a preparation method thereof, so as to solve the problem of low excitation efficiency of laser in the red fluorescent layer in the prior art.

[0004] In order to solve the above technical problems, a technical solution adopted by the present invention is: to provide a method for preparing a red light emitting module, the preparation method comprising: providing a high thermal conductivity substrate; mixing a first low-melting point glass powder with inorganic diffuse reflection particles and applying the mixture to the high thermal conductivity substrate, and then sintering to form a diffuse reflection layer; mixing an inorganic slurry formed by mixing a second low-melting point glass powder with a nitride red powder and applying the mixture to the diffuse reflection layer, and then sintering to form a red light glass layer, wherein the proportion of the nitride red powder in the inorganic slurry is not less than 25%; wherein the viscosity flow temperature of the second low-melting point glass powder is less than 600°C, the sintering temperature of the second low-melting point glass powder is less than 600°C, and the thermal expansion coefficient of the second low-melting point glass powder is less than 10*10 -6 / K.

[0005] According to an embodiment of the present invention, the preparation method further comprises: coating a third low-melting-point glass powder between the diffuse reflection layer and the high thermal conductivity substrate onto the high thermal conductivity substrate and sintering to form a glass bonding layer.

[0006] According to an embodiment of the present invention, the viscosity flow temperature of the third low-melting point glass powder is less than or equal to the viscosity flow temperature of the second low-melting point glass powder.

[0007] According to an embodiment of the present invention, the thickness of the glass bonding layer is less than or equal to 30 um.

[0008] According to an embodiment of the present invention, the glass bonding layer, the diffuse reflection layer and the red light glass layer are formed by single-layer sintering or multi-layer co-sintering.

[0009] According to one embodiment provided by the present invention, the high thermal conductivity substrate is one of an aluminum nitride substrate, a silicon carbide substrate, a silicon nitride substrate or a single crystal silicon substrate, and the inorganic diffuse reflective particles include one or more of titanium dioxide, aluminum oxide, yttrium oxide, zinc oxide, and barium sulfate.

[0010] In order to solve the above technical problems, another technical solution adopted by the present invention is: to provide a red light emitting module, the red light emitting module comprises a red light glass layer, a diffuse reflection layer and a high thermal conductivity substrate stacked in sequence; the diffuse reflection layer is mainly formed by mixing and sintering a first low-melting point glass powder and inorganic diffuse reflection particles; the red light glass layer is mainly formed by mixing and sintering a second low-melting point glass powder and a nitride red powder, the viscosity flow temperature of the second low-melting point glass powder is less than 600°C, the sintering temperature of the second low-melting point glass powder is less than 600°C, and the thermal expansion coefficient of the second low-melting point glass powder is less than 10*10 -6 / K.

[0011] According to an embodiment of the present invention, the red light emitting module further comprises a glass bonding layer disposed between the diffuse reflection layer and the high thermal conductivity substrate, wherein the glass bonding layer is mainly formed by sintering a third low melting point glass powder.

[0012] According to one embodiment provided by the present invention, the thickness of the glass bonding layer is less than or equal to 30um, the third low-melting point glass powder is the same as the second low-melting point glass powder, or the viscosity flow temperature of the third low-melting point glass powder is lower than the viscosity flow temperature of the second low-melting point glass powder.

[0013] According to one embodiment provided by the present invention, the high thermal conductivity substrate is one of an aluminum nitride substrate, a silicon carbide substrate, a silicon nitride substrate or a single crystal silicon substrate, and the inorganic diffuse reflective particles include one or more of titanium dioxide, aluminum oxide, yttrium oxide, zinc oxide, and barium sulfate.

[0014] The beneficial effects of the present invention are as follows: Different from the prior art, the present invention provides an inorganic package for the nitride red powder by low-temperature sintering. The heat dissipation performance of the nitride red powder can be effectively improved and the degradation rate of the nitride red powder can be reduced. The reliability of the entire red light emitting module can be effectively improved, and the threshold of the red light emitting module tolerating the laser power density can be improved as a whole. Compared with the silicone packaging method, the red light emitting module provided by the present invention has a higher and more stable luminous brightness under high-power laser excitation and has a higher excitation efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1It is a schematic flow chart of a first embodiment of a method for preparing a red light emitting module provided by the present invention;

[0016] Figure 2 yes Figure 1 A cross-sectional scanning electron micrograph of the prepared red light emitting module;

[0017] Figure 3 yes Figure 1 Test data diagram of the excitation effect of the prepared red light emitting module and the existing red light silicone color wheel under excitation light;

[0018] Figure 4 is a structural schematic diagram of a first embodiment of a red light emitting module provided by the present invention;

[0019] Figure 5 It is a structural schematic diagram of the second embodiment of the red light emitting module provided by the present invention. DETAILED DESCRIPTION

[0020] The following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work are within the scope of protection of the present invention.

[0021] In addition, if there are descriptions involving "first", "second", etc. in the embodiments of the present invention, the descriptions of "first", "second", etc. are only used for descriptive purposes and cannot be understood as indicating or suggesting their relative importance or implicitly indicating the number of the indicated technical features. Therefore, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features. In addition, the technical solutions between the various embodiments can be combined with each other, but they must be based on the ability of ordinary technicians in the field to implement them. When the combination of technical solutions is contradictory or cannot be implemented, it should be deemed that such a combination of technical solutions does not exist and is not within the scope of protection required by the present invention.

[0022] See also Figure 1 , Figure 1 1 is a flow chart of a first embodiment of a method for preparing a red light emitting module provided by the present invention, which specifically includes the following steps:

[0023] S11, providing a high thermal conductivity substrate.

[0024] A high thermal conductivity substrate is provided. Specifically, the high thermal conductivity substrate can be one of an aluminum nitride substrate, a silicon carbide substrate, a silicon nitride substrate or a single crystal silicon substrate. The substrate has a relatively high thermal conductivity. Specifically, the thermal conductivity of the high thermal conductivity substrate provided by the present invention is greater than 80w / mk.

[0025] S12, mixing the first low-melting-point glass powder with the inorganic diffuse reflection particles, coating the mixture on the glass bonding layer, and then sintering the mixture to form a diffuse reflection layer.

[0026] The first low-melting-point glass powder is uniformly mixed with inorganic diffuse reflection particles, coated on a high thermal conductivity substrate, and then sintered to form a diffuse reflection layer.

[0027] The inorganic diffuse reflective particles include one or more of titanium dioxide, aluminum oxide, yttrium oxide, zinc oxide, and barium sulfate.

[0028] S13, coating an inorganic slurry formed by uniformly mixing the second low-melting-point glass powder and the nitride red powder on the diffuse reflection layer, and then sintering to form a red light glass layer.

[0029] The inorganic slurry formed by mixing the second low-melting-point glass powder and the nitride red powder is mixed and coated on the diffuse reflection layer and then sintered to form a red light glass layer.

[0030] Specifically, the viscosity flow temperature of the second low melting point glass powder is less than 600° C., the sintering temperature of the second low melting point glass powder is less than 600° C., and the thermal expansion coefficient of the second low melting point glass powder is less than 10*10 -6 / K. The nitride red powder in this embodiment is specifically a phosphor, preferably, specifically (Sr,Ca)AlSiN3:Eu2+ phosphor. However, for the (Sr,Ca)AlSiN3:Eu2+ phosphor, it is easy to thermally decompose above 600°C. Therefore, by providing a low-melting-point glass powder with a viscosity flow temperature and a sintering temperature both less than 600°C, the reaction with the nitride red powder can be reduced during the sintering process, thereby reducing the degradation rate of the nitride red powder, thereby maintaining the excellence of the nitride red powder, and making the sintered red light glass layer more efficient under laser excitation.

[0031] The first low-melting point glass powder and the second low-melting point glass powder can be the same glass powder or different glass powders, but the viscosity flow temperature and sintering temperature of the first low-melting point glass powder must be less than 600°C.

[0032] In a specific embodiment, the refractive index of the first low-melting point glass frit is less than 1.5.

[0033] In a specific embodiment, when sintering the red light glass layer, the proportion of nitride red powder in the inorganic slurry mixed with nitride red powder and the second low-melting point glass powder is not less than 25%. In a preferred embodiment, the proportion of nitride red powder in the inorganic slurry mixed with nitride red powder and the second low-melting point glass powder can be greater than 33.3%, which can prevent the red light glass layer, the diffuse reflection layer and the high thermal conductivity substrate from falling off and enhance the adhesion.

[0034] In a specific embodiment, the thermal expansion coefficients of the first low-melting-point glass powder and the second low-melting-point glass powder are both less than 10*10 -6 / K.

[0035] Specifically, since the thermal expansion coefficient of the high thermal conductivity substrate is generally small, in order to prevent the problem of low adhesion between the red light glass layer, the diffuse reflection layer and the high thermal conductivity substrate due to the large difference in thermal expansion coefficient between the first low melting point glass powder and / or the second low melting point glass powder and the high thermal conductivity substrate during sintering, a high thermal conductivity substrate with a thermal expansion coefficient less than 10*10 -6 The first low melting point glass powder of / K and the second low melting point glass powder can increase the adhesion between the red light glass layer, the diffuse reflection layer and the high thermal conductivity substrate layers, prevent the red light glass layer and / or the diffuse reflection layer from falling off, so as to enhance the structural reliability of the red light emitting module.

[0036] Preferably, in order to prevent heat accumulation during the sintering process, which may cause the diffuse reflection layer and the red light glass layer to be unable to cool quickly, a high thermal conductivity substrate with a thermal conductivity greater than 80W / mk is used to quickly dissipate the heat during sintering, thereby reducing the temperature of the diffuse reflection layer and the red light glass layer, thereby improving the reliability of the red light-emitting module.

[0037] In a preferred embodiment, the sintering temperature and glass transition temperature of the first low-melting-point glass powder and the second low-melting-point glass powder are less than 100° C. Therefore, it is ensured that the sintering stress with the high thermal conductivity substrate can be reduced during the sintering process. Figure 2 As shown, during the sintering process, the red light glass layer will have certain pores, so some of the sintering stress of the red light glass layer can be dissipated through the pores, thereby improving the adhesion between the red light glass layer, the diffuse reflection layer and the high thermal conductivity substrate of the red light emitting module.

[0038] In the prior art, silica gel is generally used to encapsulate phosphors to obtain the relevant fluorescent layer. Since the thermal conductivity of silica gel is generally 0.1 to 0.2 W / mK, its heat conduction effect is poor. Since the excitation light source generally uses blue light, the Stokes displacement during the excitation process is large, and the heat generated in the fluorescent layer is large, and it cannot be conducted out in time, resulting in heat accumulation in the fluorescent layer, temperature rise, further reducing the wavelength conversion efficiency, and increasing the heat generation, which will rapidly aggravate the thermal quenching effect of the fluorescent material. In comparison, the present invention uses nitride red powder and mixes it with a second low-melting point glass powder to sinter it into a red light glass layer on a high thermal conductivity substrate to form a red light emitting module. The high thermal conductivity substrate can quickly conduct heat to the red light glass layer, so that the entire red light emitting module has good thermal conductivity. On the other hand, compared with YAG:Ce3+ or red light ceramics, the nitride red powder provided by the present invention has better light excitation performance and lower light loss.

[0039] like Figure 3 As shown, during the testing of the red light emitting module prepared by the present invention and the existing red light silicone color wheel, under a lower power blue laser, such as a 15.3W blue laser, the luminous flux of the red light emitting module is 8% lower than that of the red light silicone color wheel, and the color coordinates of the two are close, indicating that the preparation method of the present invention has a lower degradation rate for nitride red powder.

[0040] And from Figure 3 It can be further determined that when the blue laser power increases to 40.2W, the red light silicone color wheel turns black and becomes damaged, while the red light emitting module prepared by the present invention can still achieve conversion and higher power, and can continuously improve the luminous flux. Compared with the silicone packaging method, it has better adaptability, brightness and stability. Therefore, the red light emitting module provided by the present invention can be better suitable for high-power lasers or LED light sources.

[0041] Preferably, the viscosity flow temperature of the second low melting point glass powder is less than 580°C, the sintering temperature of the second low melting point glass powder is less than 580°C, and the thermal expansion coefficient of the second low melting point glass powder is less than 8*10 -6 / K.

[0042] Preferably, the viscosity flow temperature of the second low melting point glass powder is less than 560°C, the sintering temperature of the second low melting point glass powder is less than 560°C, and the thermal expansion coefficient of the second low melting point glass powder is less than 6*10 -6 / K.

[0043] The first low-melting-point glass powder and the second glass powder can be the same. In addition, by reducing the viscosity flow temperature and sintering temperature of the first low-melting-point glass powder and the second low-melting-point glass powder, the degradation rate of the nitride red powder during the sintering process can be further reduced. And by reducing the thermal expansion coefficient of the first low-melting-point glass powder and the second glass powder, the thermal expansion coefficient can be further approached to the thermally conductive substrate, thereby reducing the sintering stress and enhancing the reliability of the entire red light emitting module.

[0044] In other embodiments, the preparation method provided by the present invention may further include coating a third low-melting-point glass powder between the diffuse reflection layer and the high thermal conductivity substrate onto the high thermal conductivity substrate and sintering to form a glass bonding layer.

[0045] Specifically, the third low melting point glass powder can be first applied to the high thermal conductivity substrate and sintered to form a glass bonding layer, and then the first low melting point glass powder is mixed with inorganic diffuse reflection particles and applied to the glass bonding layer and sintered to form a diffuse reflection layer.

[0046] Among them, the third low-melting point glass powder can be the same as or different from the second low-melting point glass powder, but if the third low-melting point glass powder is different from the second low-melting point glass powder, the viscosity flow temperature of the third low-melting point glass powder is less than or equal to the viscosity flow temperature of the second low-melting point glass powder.

[0047] In a specific embodiment, the thickness of the glass bonding layer is less than 30 um. Preferably, the thickness of the glass bonding layer is less than 20 um.

[0048] In another embodiment, the thickness of the glass bonding layer is less than 10 um.

[0049] In a specific embodiment, if a glass bonding layer is required to be prepared between the diffuse reflection layer and the high thermal conductivity substrate, the proportion of nitride red powder in the inorganic slurry mixed with nitride red powder and the second low melting point glass powder is not less than 25%, thereby ensuring the adhesion between the layers of the red light emitting module.

[0050] In a specific embodiment, the glass bonding layer, the diffuse reflection layer and the red light glass layer can be sintered in a single layer, that is, the glass bonding layer, the diffuse reflection layer and the red light glass layer can be sintered in sequence on a high thermal conductivity substrate.

[0051] In another embodiment, since the sintering temperatures of the first low-melting-point glass powder, the second low-melting-point glass powder and the third low-melting-point glass powder are the same or similar, the glass bonding layer, the diffuse reflection layer and the red light glass layer can be formed by co-sintering multiple layers. That is, the third low-melting-point glass powder, the mixture of the first low-melting-point glass powder and inorganic diffuse reflection particles, and the second low-melting-point glass powder and nitride red powder are sequentially arranged on the high thermal conductivity substrate to form an inorganic slurry, and sintered simultaneously.

[0052] In another embodiment, one of the glass bonding layer, the diffuse reflection layer and the red light glass layer may be sintered as a single layer, and the other two layers may be co-sintered, which is not limited here.

[0053] In the above-mentioned embodiments, by preparing a glass bonding layer between the diffuse reflection layer and the high thermal conductivity substrate, on the one hand, because the glass bonding layer has better melt fluidity at high temperature than the red light glass layer and the diffuse reflection layer, during the sintering and cooling process, specifically near the glass transition temperature, the sintering shrinkage of the red light glass layer and the diffuse reflection layer can be dissipated by the better fluidity of the pure glass layer. The thermal stress between the red light glass layer and the diffuse reflection layer and the high thermal conductivity substrate during the sintering process can be effectively reduced to improve the bonding performance between the layers, thereby increasing the reliability of the red light emitting module.

[0054] like Figure 4 As shown, the present invention further provides a red light emitting module 20, which includes a red light glass layer 100, a diffuse reflection layer 200 and a high thermal conductivity substrate 300 stacked in sequence.

[0055] The diffuse reflection layer 200 is mainly formed by mixing and sintering a first low-melting-point glass powder and inorganic diffuse reflection particles.

[0056] The red light glass layer 100 is mainly formed by mixing and sintering the second low melting point glass powder and the nitride red powder, and the viscosity flow temperature of the second low melting point glass powder is less than 600°C, the sintering temperature of the second low melting point glass powder is less than 600°C, and the thermal expansion coefficient of the second low melting point glass powder is less than 10*10 -6 / K.

[0057] like Figure 5 As shown, the red light emitting module 20 provided by the present invention further includes a glass bonding layer 400, which is disposed between the diffuse reflection layer 200 and the high thermal conductivity substrate 300. The glass bonding layer 400 is mainly formed by sintering the third low melting point glass powder.

[0058] The thickness of the glass bonding layer 400 is less than or equal to 30 um, the third low-melting point glass frit is the same as the second low-melting point glass frit, or the viscosity flow temperature of the third low-melting point glass frit is lower than the viscosity flow temperature of the second low-melting point glass frit.

[0059] In a specific embodiment, the high thermal conductivity substrate 300 is one of an aluminum nitride substrate, a silicon carbide substrate, a silicon nitride substrate or a single crystal silicon substrate, and the inorganic diffuse reflective particles include one or more of titanium dioxide, aluminum oxide, yttrium oxide, zinc oxide, and barium sulfate.

[0060] In summary, the present invention provides a red light emitting module and a preparation method thereof, by adopting low temperature sintering inorganic packaging for nitride red powder. The heat dissipation performance of nitride red powder can be effectively improved and the degradation rate of nitride red powder can be reduced. Furthermore, by preparing a glass bonding layer on the diffuse reflection layer and the high thermal conductivity substrate, the adhesion between the layers of the red light emitting module can be increased. Through the above-mentioned method, the reliability of the entire red light emitting module can be effectively improved, and the threshold of the red light emitting module to withstand laser power density can be improved as a whole. Compared with the silica gel packaging method, the red light emitting module provided by the present invention has higher and more stable luminous brightness under high-power laser excitation. In addition, in the preparation method provided by the present invention, the mixture of the first low-melting point glass powder and the white diffuse reflection particles and the inorganic slurry formed by uniformly mixing the second low-melting point glass powder and the nitride red powder can be suitable for a printing process with controllable thickness and shape, so that the process of the entire preparation method is simple and reliable, so that the red light emitting module can be mass-produced.

[0061] The above are only implementation modes of the present invention, and are not intended to limit the patent scope of the present invention. Any equivalent results or equivalent process changes made using the contents of the present invention's specification and drawings, or directly or indirectly applied in other related technical fields, are also included in the patent protection scope of the present invention.

Claims

1. A method for preparing a red light emitting module, characterized in that: The preparation method comprises: Provide high thermal conductivity substrate; Mixing a first low-melting-point glass powder with inorganic diffuse reflection particles, coating the mixture on the high thermal conductivity substrate, and then sintering the mixture to form a diffuse reflection layer; The inorganic slurry formed by mixing the second low-melting-point glass powder and the nitride red powder is mixed and coated on the diffuse reflection layer and then sintered to form a red light glass layer, wherein the nitride red powder accounts for no less than 25% of the inorganic slurry; The viscosity flow temperature of the second low-melting-point glass powder is less than 600°C, the sintering temperature of the second low-melting-point glass powder is less than 600°C, and the thermal expansion coefficient of the second low-melting-point glass powder is less than 10*10 -6 / K, the nitride red powder is (Sr,Ca)AlSiN3:Eu2+ phosphor; Wherein, the preparation method further comprises: A third low-melting-point glass powder is applied to the high-thermal-conductivity substrate between the diffuse reflection layer and the high-thermal-conductivity substrate and sintered to form a glass bonding layer; The viscosity flow temperature of the third low-melting point glass powder is less than or equal to the viscosity flow temperature of the second low-melting point glass powder.

2. The preparation method according to claim 1, characterized in that: The thickness of the glass bonding layer is less than or equal to 30 um.

3. The preparation method according to claim 1, characterized in that: The glass bonding layer, the diffuse reflection layer and the red light glass layer are formed by single-layer sintering or multi-layer co-sintering.

4. The preparation method according to claim 1, characterized in that: The high thermal conductivity substrate is one of an aluminum nitride substrate, a silicon carbide substrate, a silicon nitride substrate or a single crystal silicon substrate, and the inorganic diffuse reflective particles include one or more of titanium dioxide, aluminum oxide, yttrium oxide, zinc oxide, and barium sulfate.

5. A red light emitting module, characterized in that: The red light emitting module comprises a red light glass layer, a diffuse reflection layer, a glass bonding layer and a high thermal conductivity substrate stacked in sequence; The diffuse reflection layer is mainly formed by mixing and sintering a first low-melting-point glass powder and inorganic diffuse reflection particles; The red light glass layer is mainly formed by mixing and sintering a second low-melting point glass powder and a nitride red powder, wherein the viscosity flow temperature of the second low-melting point glass powder is less than 600° C., the sintering temperature of the second low-melting point glass powder is less than 600° C., and the thermal expansion coefficient of the second low-melting point glass powder is less than 10*10-6 / K; The glass bonding layer is mainly formed by coating a third low-melting-point glass powder between the diffuse reflection layer and the high thermal conductivity substrate and sintering the third low-melting-point glass powder, and the viscosity flow temperature of the third low-melting-point glass powder is less than or equal to the viscosity flow temperature of the second low-melting-point glass powder.

6. The red light emitting module according to claim 5, characterized in that: The red light emitting module further comprises a glass bonding layer disposed between the diffuse reflection layer and the high thermal conductivity substrate, wherein the glass bonding layer is mainly formed by sintering a third low melting point glass powder.

7. The red light emitting module according to claim 6, characterized in that: The thickness of the glass bonding layer is less than or equal to 30 um, the third low-melting point glass powder is the same as the second low-melting point glass powder, or the viscosity flow temperature of the third low-melting point glass powder is lower than the viscosity flow temperature of the second low-melting point glass powder.

8. The red light emitting module according to any one of claims 5 to 7, characterized in that: The high thermal conductivity substrate is one of an aluminum nitride substrate, a silicon carbide substrate, a silicon nitride substrate or a single crystal silicon substrate, and the inorganic diffuse reflective particles include one or more of titanium dioxide, aluminum oxide, yttrium oxide, zinc oxide, and barium sulfate.

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