An inorganic fluorescent conversion element for laser lighting and display and its preparation and application

Abstract

The present invention belongs to the technical field of laser lighting and laser display, and discloses an inorganic fluorescent conversion element for laser lighting and display, and its preparation and application. The inorganic fluorescent conversion element comprises a fluorescent glass layer (1), a Ti / Cu seed layer (3), a composite coating (2), and a heat dissipation substrate (4); wherein the upper surface of the heat dissipation substrate (4) is covered by the fluorescent glass layer (1), and the side surfaces and upper surfaces thereof are both coated by the Ti / Cu seed layer (3); the Ti / Cu seed layer (3) is a stacked structure of a Ti layer and a Cu layer; and the composite coating (2) is a metal copper electroplating layer doped with nano- and / or micron-sized heat-conducting particles (22). The present invention utilizes the fully coated heat-conducting structure of the composite coating to improve the heat dissipation performance of the fluorescent glass layer, while the Ti layer in the seed layer also improves the back extraction of photons, effectively improving the luminous brightness of the laser light source (especially the white laser light source).

Description

Technical Field

[0001] The present invention belongs to the technical field of laser lighting and laser display, and more specifically, relates to an inorganic fluorescent conversion element for laser lighting and display, and the preparation and application thereof. Background Art

[0002] Laser illumination technology is known for its ultra-high power (e.g., 30 W / mm 2 Laser display technology, with its advantages of high brightness (e.g., over 5,000 lumens), high collimation, long illumination distance, and higher conversion efficiency at high current densities, is gradually replacing traditional light sources and is widely used in automotive headlights, aviation lighting, medical and health care, specialty lighting, visible light communications, and other fields. Laser display technology is also the mainstream technology for future high-end displays such as large-screen projection, automotive flat-panel displays, digital cinemas, and mobile phone projection.

[0003] Current laser lighting and laser backlight display technologies often utilize fluorescent conversion white light laser sources, where a blue laser chip remotely excites a yellow phosphor layer. This approach includes both transmissive and reflective laser sources. Due to the small irradiation spot size and high laser power density of the blue laser chip, the phosphor layer must withstand high laser radiation energy and fluorescence conversion heat. Traditional organic fluorescent resins have poor heat resistance and low thermal conductivity, and are susceptible to thermal corrosion and carbonization under high-power-density laser excitation, making them difficult to meet the packaging requirements of white light laser sources. Consequently, conversion materials based on fluorescent glass have gradually become a research focus.

[0004] Fluorescent glass is an inorganic composite material composed of glass and phosphors, which has the advantages of high thermal stability, easy control of optical properties, simple preparation process and low cost. However, due to the low thermal conductivity of the fluorescent glass layer, traditional single-sided heat dissipation structures such as ceramic-based and sapphire-based ones are prone to thermal deposition failure on the outer surface away from the heat dissipation substrate under high-power laser excitation, which has a great impact on the luminous brightness and thermal stability of the white laser light source (for example, the existing technology has used Cu sheets to form fluorescent glass through medium and low temperature co-firing, but under the high temperature conditions of the laser, the fluorescent glass will be damaged due to the difference in thermal expansion coefficient); at the same time, the reflective fluorescent conversion element has a serious light absorption effect, which makes it difficult to meet the laser drive or excitation requirements, limiting the development of laser lighting technology. Therefore, there is an urgent need to propose a high luminescence saturation threshold (greater than 30W / mm 2 ), inorganic fluorescent conversion elements with high light extraction (luminous efficiency greater than 200 lm / W) to meet the needs of high-power laser lighting and laser display. Summary of the Invention

[0005] To address the aforementioned deficiencies or improvements in the prior art, the present invention aims to provide an inorganic fluorescent conversion element for laser lighting and display, as well as its preparation and application. The fully encapsulated thermally conductive structure of the composite coating improves the heat dissipation performance of the fluorescent glass layer. The Ti layer in the seed layer also enhances backscattering of photons, effectively increasing the luminous brightness of the laser light source (particularly white laser light sources). The inorganic fluorescent conversion element of the present invention does not utilize organic adhesives, thus preventing the failure or even carbonization of organic materials under high-power laser excitation and high temperatures. This improves the long-term reliability of the inorganic fluorescent conversion element and addresses the failure of traditional single-sided heat dissipation structures under high-power laser excitation.

[0006] To achieve the above-mentioned object, according to one aspect of the present invention, there is provided an inorganic fluorescent conversion element for reflective laser lighting or laser display, comprising a fluorescent glass layer, a Ti / Cu seed layer, a composite coating and a heat dissipation substrate; wherein,

[0007] Part or all of the upper surface of the heat dissipation substrate is covered by the fluorescent glass layer, and the two are closely connected; when part of the upper surface of the heat dissipation substrate is covered by the fluorescent glass layer, the side surface and the upper surface of the fluorescent glass layer, the side surface of the heat dissipation substrate, and the upper surface not covered by the fluorescent glass layer are all covered by the Ti / Cu seed layer; when the entire upper surface of the heat dissipation substrate is covered by the fluorescent glass layer, the side surface and the upper surface of the fluorescent glass layer, and the side surface of the heat dissipation substrate are all covered by the Ti / Cu seed layer;

[0008] The upper surface and side surfaces of the Ti / Cu seed layer are completely covered by the composite coating; the Ti / Cu seed layer is a stacked structure of a Ti layer and a Cu layer, wherein the Cu layer is in direct contact with the composite coating; the composite coating is a metal copper electroplating layer doped with nano- and / or micron-sized thermally conductive particles.

[0009] As a further preferred embodiment of the present invention, the transmittance of the heat dissipation substrate is not less than 60% in the wavelength range of 430-480 nm, and the material of the heat dissipation substrate is transparent sapphire or diamond.

[0010] As a further preferred embodiment of the present invention, the overall reflectivity of the composite coating is not less than 90% in the wavelength band of 430-480 nm.

[0011] As a further preferred embodiment of the present invention, the thickness of the fluorescent glass layer is 60-200 μm;

[0012] The thickness of the Ti / Cu seed layer is 100-200 nm;

[0013] The thickness of the composite coating is 100-250 μm.

[0014] As a further preferred embodiment of the present invention, the material used for the thermally conductive particles satisfies a thermal conductivity greater than 30 W / (m·K);

[0015] In the composite coating, the volume proportion of the thermally conductive particles is 10% to 50%.

[0016] As a further preferred embodiment of the present invention, the material used for the thermally conductive particles is one or more of diamond, boron nitride or aluminum oxide.

[0017] According to another aspect of the present invention, the present invention provides a method for preparing the above-mentioned inorganic fluorescent conversion element for reflective laser lighting or laser display, comprising the following steps:

[0018] S1. Prepare a fluorescent glass slurry, apply the fluorescent glass slurry on a heat dissipation substrate to form a fluorescent glass slurry layer, and then co-fire to melt the glass, thereby covering a portion of the upper surface of the heat dissipation substrate to form a fluorescent glass layer;

[0019] S2. Depositing a Ti layer and a Cu layer on the side surface and the top surface of the fluorescent glass layer, the side surface of the heat dissipation substrate and the top surface not covered by the fluorescent glass layer by a magnetron sputtering process to obtain a Ti / Cu seed layer;

[0020] S3. Using a copper electroplating solution doped with nano- and / or micron-sized thermally conductive particles, a composite coating is prepared on the upper surface and side surfaces of the Ti / Cu seed layer through an electroplating process, thereby obtaining an inorganic fluorescent conversion element for reflective laser lighting or laser display.

[0021] As a further preferred embodiment of the present invention, in step S1, the coating is performed by screen printing;

[0022] The fluorescent glass paste is made by mixing raw materials including fluorescent powder, glass powder and organic solvent;

[0023] The phosphor is a single-color phosphor or a multi-color phosphor;

[0024] The mass ratio of the phosphor to the glass powder is (0.3-2):1;

[0025] The glass powder is a low-temperature glass powder having a glass transition temperature not exceeding 700°C;

[0026] The temperature used for the co-firing is 550-700° C.; and the sintering time is 40-90 minutes.

[0027] According to another aspect of the present invention, the present invention provides an application of the above-mentioned inorganic fluorescent conversion element for reflective laser lighting or laser display, which is used for laser lighting or laser display, with a luminous flux of more than 5000 lm and a laser power density of 30W / mm 2 above.

[0028] As a further preferred embodiment of the present invention, the laser illumination and the laser display are used for fluorescence conversion of white light laser light sources.

[0029] Compared with the prior art, the above technical solutions conceived by the present invention can achieve the following beneficial effects:

[0030] (1) The inorganic fluorescent conversion element obtained by the present invention has a reflective structure, and the composite coating and the heat dissipation substrate achieve full coverage heat dissipation of the fluorescent conversion element. When the inorganic fluorescent conversion element obtained by the present invention is used, the laser is incident from below the heat dissipation substrate, travels to the fluorescent glass layer, and encounters the phosphor particles to stimulate fluorescence. At the same time, the light is reflected after encountering the Ti layer in the seed layer, thus forming a reflective structure. In the laser field, existing technologies have used Cu sheets to form fluorescent glass through medium and low temperature co-firing. However, due to differences in thermal expansion coefficients, the local temperature will rise rapidly under high-power laser excitation conditions, and the fluorescent glass will be damaged. In addition, electroplating processing technology is rarely used in the laser field. The present invention forms a composite Cu layer by electroplating on a heat dissipation substrate-fluorescent glass sheet, and achieves full coverage heat dissipation through the upper composite Cu layer and the lower heat dissipation substrate. The composite coating can achieve heat conduction above and to the sides of the fluorescent glass layer, thereby improving reliability. At the same time, the Ti layer in the seed layer can also improve the light efficiency (this is because the Cu layer has severe photon absorption, while the Ti layer in the seed layer has a reflective effect and can be used for back-light extraction of the fluorescent glass layer), and the heat dissipation substrate can also achieve heat conduction below the fluorescent glass layer.

[0031] (2) The reflective inorganic fluorescent conversion element obtained by the present invention is a high luminescence saturation threshold (greater than 30W / mm 2 ), high light extraction (luminous efficiency greater than 200 lm / W), and can be used in high-laser saturation threshold fluorescence conversion white laser light sources, meeting the needs of high-power laser lighting and laser displays. The inorganic fluorescence conversion element of this invention can be used in high-brightness fluorescence conversion white laser light sources, capable of withstanding high-power density laser drive or excitation, enabling white laser light engines and devices with ultra-high brightness and reliability, thus promoting the development of laser lighting technology.

[0032] (3) The composite coating of the reflective inorganic fluorescent conversion element obtained by the present invention is doped with micron-sized thermally conductive particles, which improves the overall thermal conductivity of the fluorescent conversion element and effectively alleviates the problem of excessive internal stress and cracking of the electroplated metal layer in micron-sized thick film electroplating. It optimizes the problem of insufficient heat conduction of the fluorescent glass layer and ensures the reliability of the element in long-term operation under high laser power input. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic structural diagram of an inorganic fluorescent conversion element for laser lighting and display provided by an embodiment of the present invention.

[0034] Figure 2 Schematic diagram of the enlarged structure of the composite coating in an embodiment of the present invention.

[0035] Figure 3 This is a flow chart of the preparation process of an inorganic fluorescent conversion element for laser lighting and display provided by an embodiment of the present invention.

[0036] Figure 1 、 Figure 2 In the figure, the meanings of the respective reference numerals are as follows: 1 is a fluorescent glass layer, 2 is a composite coating layer, 3 is a Ti / Cu seed layer, 4 is a heat dissipation substrate, 21 is a copper substrate, and 22 is a thermal conductive particle. DETAILED DESCRIPTION

[0037] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely for the purpose of explaining the present invention and are not intended to limit the present invention. In addition, the technical features involved in the various embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.

[0038] Example 1

[0039] An inorganic fluorescent conversion element for laser lighting and laser display, such as Figure 1As shown, it includes: a fluorescent glass layer 1, a composite coating 2, a Ti / Cu seed layer 3, and a heat sink substrate 4; wherein the fluorescent glass layer 1 is located on the upper surface of the heat sink substrate 4, the Ti / Cu seed layer 3 is located on the upper surface and side surfaces of the heat sink substrate 4 and the fluorescent glass layer 1, and the composite coating 2 is arranged above and on the side surfaces of the Ti / Cu seed layer 3 (completely covering the Ti / Cu seed layer 3; wherein the Ti / Cu seed layer 3 is a stacked structure of a Ti layer and a Cu layer, the Ti layer is in direct contact with the fluorescent glass layer 1, and the Cu layer is in direct contact with the composite coating 2); the heat sink substrate 4 meets the requirement of a transmittance greater than 60% in the wavelength band of 430-480nm; the composite coating 2 meets the requirement of a reflectivity greater than 90% in the wavelength band of 430-480nm; the inorganic fluorescent conversion element is a reflective structure, and high-power blue light (e.g., 3W; of course, other power settings above 3W can also be used) excites yellow phosphor from one side of the heat sink substrate to obtain white light for laser lighting or display.

[0040] The preparation method of the inorganic fluorescent conversion element is as follows: Figure 3 As shown, it mainly includes the following steps:

[0041] Step 1: Preparation of phosphor. Select a sapphire substrate with a thickness of 1mm; select a sapphire substrate with a length and width of 15mm; mix 0.5g of YAG phosphor with 1.5g of Schott glass powder (chemical composition is 25B2O3-10SiO2-35ZnO-6Li2O-12La2O3-12WO3; the Arabic numerals before each component in the chemical composition represent the molar percentage of the component. Taking 25B2O3 as an example, the molar percentage of B2O3 in the glass powder is 25%; the same below), and 0.35g of turpentine alcohol to form a fluorescent glass slurry, and apply it on the surface of a sapphire heat dissipation substrate with a thickness of 1mm through a screen printing process; the area of ​​the fluorescent glass layer is 20mm 2 (Of course, other area settings can also be used, as long as part or all of the upper surface of the heat sink substrate is covered by the fluorescent glass layer; for example, 20~40mm 2 other areas within the interval); and then sintered at 700°C (sintering time is 90 min) to obtain a fluorescent glass film with a thickness of 0.1 mm.

[0042] Step 2: A seed layer is prepared on the upper surface of the fluorescent glass layer and the side of the sapphire by magnetron sputtering. The materials are Ti metal and Cu metal (the target materials are titanium target and copper target with a purity of 99.999%), which are used for backlight extraction from the fluorescent glass layer. The process parameters of magnetron sputtering are: vacuum degree 3.0×10 −4The conditions were: 1 Pa, substrate temperature 25°C, target-substrate distance 6 cm, DC power 1500 W, argon flow rate 30 mL / min, sputtering pressure 0.5 Pa, and sputtering time 100 s (the Ti target was sputtered first, followed by the Cu target; the sputtering time for the Ti target was 50 s, and the sputtering time for the Cu target was 50 s). The resulting seed layer had a thickness of 100 nm, of which the Ti layer had a thickness of 50 nm and the Cu layer had a thickness of 50 nm.

[0043] Step 3: Electroplating copper on the outer surface of the seed layer. The working temperature of the electroplating additive is 25°C; the current density is 6.5 A / cm 2 The plating rate was 100 μm / h. The plating solution consisted of 187.5 g / L copper sulfate pentahydrate, 60 g / L sulfuric acid, 50 mg / L sodium chloride, 300 mg / L polyethylene glycol, and 6 mg / L sodium thiazolinyldithiopropanesulfonate. The stirring rate was 400 rpm. Diamond micropowder with a particle size of 100 microns was added to the plating solution at a concentration of 50 g / L.

[0044] Comparative Example 1

[0045] The preparation process of this comparative example 1 is substantially the same as that of Example 1, with the only difference being that no thermally conductive particles are added to the electroplating solution in step 3; the corresponding electroplated copper layer will crack due to excessive internal stress, and a device with the desired structure cannot be obtained.

[0046] Comparative Example 2

[0047] Comparative Example 2 is a method for preparing a conventional sapphire-based fluorescence conversion element, which only includes step 1 of Example 1 (all parameters and conditions in step 1 are consistent with those in step 1 of Example 1), without steps 2 and 3.

[0048] Example 2

[0049] An inorganic fluorescent conversion element for laser lighting and display, such as Figure 1As shown, it includes: a fluorescent glass layer 1, a composite coating 2, a Ti / Cu seed layer 3, and a heat sink substrate 4; wherein the fluorescent glass layer 1 is located on the upper surface of the heat sink substrate 4, the Ti / Cu seed layer 3 is located on the upper surface and side surfaces of the heat sink substrate 4 and the fluorescent glass layer 1, and the composite coating 2 is arranged above and on the side surfaces of the Ti / Cu seed layer 3 (completely covering the Ti / Cu seed layer 3; wherein the Ti / Cu seed layer 3 is a stacked structure of a Ti layer and a Cu layer, the Ti layer is in direct contact with the fluorescent glass layer 1, and the Cu layer is in direct contact with the composite coating 2); the heat sink substrate 4 meets the requirement of a transmittance greater than 70% in the wavelength band of 430-480nm; the composite coating 2 meets the requirement of a reflectivity greater than 90% in the wavelength band of 430-480nm; the inorganic fluorescent conversion element is a reflective structure, and high-power blue light (e.g., power 3W) excites yellow phosphor from one side of the heat sink substrate to obtain white light for laser lighting or display.

[0050] The preparation method of the inorganic fluorescent conversion element is as follows: Figure 3 As shown, it mainly includes the following steps:

[0051] Step 1: Preparation of phosphor. Select a 1.5mm thick sapphire substrate with a length and width of 15mm. Mix 1g of YAG phosphor with 0.5g of low-temperature glass powder (chemical composition: 20Bi2O3-60B2O3-10ZnO-10BaO) and 0.32g of turpentine to form a fluorescent glass paste. Apply it to the surface of a 1.5mm thick sapphire heat sink substrate using a screen printing process. The fluorescent glass layer covers an area of ​​40mm. 2 ; After sintering at 550℃ (sintering time is 40min), a fluorescent glass film with a thickness of 0.2 mm was obtained.

[0052] Step 2: A seed layer is prepared on the upper surface of the fluorescent glass layer and the side of the sapphire by magnetron sputtering. The materials are Ti metal and Cu metal (the target materials are titanium target and copper target with a purity of 99.999%), which are used for backlight extraction from the fluorescent glass layer. The process parameters of magnetron sputtering are: vacuum degree of 3.5×10 −4 Pa, substrate temperature 30°C, target-substrate distance 6.5 cm, DC power supply power 1200 W, argon flow rate 45 mL / min, sputtering pressure 0.5 Pa, sputtering time 200 s (Ti target sputtered first, then Cu target; the sputtering time of Ti target was 100 s, and the sputtering time of Cu target was 100 s). The resulting seed layer thickness was 200 nm, of which the thickness of the Ti layer was 100 nm and the thickness of the Cu layer was 100 nm.

[0053] Step 3: Electroplating copper on the outer surface of the seed layer. The working temperature of the electroplating additive is 25°C; the current density is 8 A / cm 2The plating rate was 100 μm / h. The plating solution consisted of 195.5 g / L copper sulfate pentahydrate, 75 g / L sulfuric acid, 45 mg / L sodium chloride, 300 mg / L polyethylene glycol, and 8.5 mg / L sodium thiazolinyldithiopropanesulfonate. The stirring rate was 500 rpm. Diamond micropowder with a particle size of 400 μm and a dosage of 10 g / L was added to the plating solution.

[0054] Comparative Example 3

[0055] The preparation process of this comparative example 3 is substantially the same as that of Example 2, except that no thermally conductive particles are added to the electroplating solution in step 3; the corresponding electroplated copper layer will crack due to excessive internal stress, and a device with the desired structure cannot be obtained.

[0056] Comparative Example 4

[0057] Comparative Example 4 is a method for preparing a conventional sapphire-based fluorescence conversion element, which only includes step 1 of Example 2 (all parameters and conditions in step 1 are consistent with those in step 1 of Example 2), without steps 2 and 3.

[0058] The fully encapsulated heat-dissipating inorganic fluorescent conversion element prepared in Example 1 has a luminous efficiency of 214 lm / W under 3 W laser irradiation, compared to the traditional sapphire-based fluorescent conversion element prepared in Comparative Example 2, which has a luminous efficiency of only 186 lm / W. The laser power saturation threshold is 10 W / mm higher than that of the device obtained in Comparative Example 2. 2 Increased to 36 W / mm 2 The corresponding luminous flux under the saturation threshold is increased from 1836 lm in the device obtained in Comparative Example 2 to 5384 lm. It can be seen that the fully encapsulated heat-dissipating inorganic fluorescent conversion element prepared in Example 1 can meet the requirements of high thermal conductivity and high light extraction in laser lighting applications.

[0059] The fully encapsulated heat-dissipating inorganic fluorescent conversion element prepared in Example 2 has a luminous efficiency of 205 lm / W under 3 W laser irradiation, compared to the traditional sapphire-based fluorescent conversion element prepared in Comparative Example 4, which has a luminous efficiency of only 178 lm / W. The laser power saturation threshold is 17 W / mm higher than that of the device obtained in Comparative Example 4. 2 Increased to 42 W / mm 2 The corresponding luminous flux under the saturation threshold is increased from 2085 lm of the device obtained in Comparative Example 4 to 5983 lm. It can be seen that Example 2 also meets the requirements of high thermal conductivity and high light extraction for laser lighting applications.

[0060] Example 3

[0061] The preparation process of Example 3 is basically the same as that of Example 2, except that the sapphire substrate in step 1 is replaced with a diamond substrate of the same size. -1 ·K -1 ), the prepared fluorescence conversion element has a laser power saturation threshold of 17 W / mm compared to the traditional sapphire-based fluorescence conversion element. 2 Increased to 58 W / mm 2 ; The corresponding luminous flux at the saturation threshold is increased from 2085 lm of the device obtained in Comparative Example 4 to 7856 lm.

[0062] The above embodiments are merely examples. For example, in addition to covering a partial area of ​​the upper surface of the heat sink substrate, the fluorescent glass layer may also cover the entire upper surface of the heat sink substrate. For another example, the length, width and thickness of the heat sink substrate 4 may all be configured in other ways (for example, the thickness of the heat sink substrate 4 may also be other thicknesses within the range of 0.3 mm to 3 mm; the overall thickness of the corresponding inorganic fluorescent conversion element may vary from 0.5 mm to 3.5 mm). Furthermore, in addition to sapphire substrates, substrates with good thermal conductivity, such as diamond substrates, may also be used, as long as the heat sink substrate + glass layer as a whole has a certain rigidity. The thickness of the Ti layer and the thickness of the Cu layer in the seed layer may also be adjusted separately. The fluorescent glass slurry may also adopt other formulations reported in the prior art.

[0063] It will be easily understood by those skilled in the art that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included in the scope of protection of the present invention.

Claims

1. An inorganic fluorescent conversion element for reflective laser lighting or laser display, characterized in that: It comprises a fluorescent glass layer (1), a Ti / Cu seed layer (3), a composite coating (2) and a heat dissipation substrate (4); wherein, Part or all of the upper surface of the heat dissipation substrate (4) is covered by the fluorescent glass layer (1), and the two are closely connected; when part of the upper surface of the heat dissipation substrate (4) is covered by the fluorescent glass layer (1), the side surface and the upper surface of the fluorescent glass layer (1), the side surface of the heat dissipation substrate (4) and the upper surface not covered by the fluorescent glass layer (1) are all covered by the Ti / Cu seed layer (3); when the entire upper surface of the heat dissipation substrate (4) is covered by the fluorescent glass layer (1), the side surface and the upper surface of the fluorescent glass layer (1), and the side surface of the heat dissipation substrate (4) are all covered by the Ti / Cu seed layer (3); The upper surface and side surfaces of the Ti / Cu seed layer (3) are completely covered by the composite coating (2); the Ti / Cu seed layer (3) is a stacked structure of a Ti layer and a Cu layer, wherein the Cu layer is in direct contact with the composite coating (2); and the composite coating (2) is a metal copper electroplating layer doped with nano- and / or micron-sized thermally conductive particles (22).

2. The inorganic fluorescent conversion element for reflective laser lighting or laser display according to claim 1, wherein: The heat dissipation substrate (4) has a transmittance of not less than 60% in the wavelength range of 430-480 nm, and the heat dissipation substrate (4) is made of transparent sapphire or diamond.

3. The inorganic fluorescent conversion element for reflective laser lighting or laser display according to claim 1, wherein: The overall reflectivity of the composite coating (2) is not less than 90% in the wavelength range of 430-480 nm.

4. The inorganic fluorescent conversion element for reflective laser lighting or laser display according to claim 1, wherein: The thickness of the fluorescent glass layer (1) is 60-200 μm; The thickness of the Ti / Cu seed layer (3) is 100-200 nm; The thickness of the composite coating (2) is 100-250 μm.

5. The inorganic fluorescent conversion element for reflective laser lighting or laser display according to claim 1, wherein: The material used for the thermally conductive particles (22) satisfies a thermal conductivity greater than 30 W / (m·K); In the composite coating (2), the volume proportion of the heat-conducting particles (22) is 10% to 50%.

6. The inorganic fluorescent conversion element for reflective laser lighting or laser display according to claim 5, wherein: The material used for the thermally conductive particles (22) is one or more of diamond, boron nitride or aluminum oxide.

7. The method for preparing an inorganic fluorescent conversion element for reflective laser lighting or laser display according to any one of claims 1 to 6, characterized in that: The following steps are involved: S1. Prepare a fluorescent glass slurry, apply the fluorescent glass slurry on a heat dissipation substrate to form a fluorescent glass slurry layer, and then co-fire to melt the glass, thereby covering a portion of the upper surface of the heat dissipation substrate to form a fluorescent glass layer; S2. Depositing a Ti layer and a Cu layer on the side surface and the top surface of the fluorescent glass layer, the side surface of the heat dissipation substrate and the top surface not covered by the fluorescent glass layer by a magnetron sputtering process to obtain a Ti / Cu seed layer; S3. Using a copper electroplating solution doped with nano- and / or micron-sized thermally conductive particles, a composite coating is prepared on the upper surface and side surfaces of the Ti / Cu seed layer through an electroplating process, thereby obtaining an inorganic fluorescent conversion element for reflective laser lighting or laser display.

8. The preparation method according to claim 7, wherein: In step S1, the coating is performed by screen printing; The fluorescent glass paste is made by mixing raw materials including fluorescent powder, glass powder and organic solvent; The phosphor is a single-color phosphor or a multi-color phosphor; The mass ratio of the phosphor to the glass powder is (0.3-2):1; The glass powder is a low-temperature glass powder having a glass transition temperature not exceeding 700°C; The temperature used for the co-firing is 550-700° C.; and the sintering time is 40-90 minutes.

9. Use of the inorganic fluorescent conversion element for reflective laser lighting or laser display according to any one of claims 1 to 6, characterized in that: For laser lighting or laser display, the luminous flux is more than 5000 lm and the laser power density is 30W / mm 2 above.

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