Wavelength conversion device and method for preparing the same

Abstract

This solution belongs to the field of lighting technology and discloses a wavelength conversion device and a preparation method thereof. The preparation method of the wavelength conversion device includes preparing a fluorescent ceramic: processing a fluorescent ceramic material into a first hollow cylinder, cutting the first hollow cylinder to form two or more sector ring cylinders having an inner side surface, an outer side surface and a cut surface, and performing polishing treatment; preparing a pre-bonding layer: coating a reflective slurry on the inner side surface, the outer side surface and the cut surface of each sector ring cylinder, and baking to obtain a sector ring cylinder with a pre-bonding layer; assembling the sector ring cylinders: assembling the sector ring cylinders with the pre-bonding layer together and performing pre-sintering to form a second hollow cylinder; preparing a fluorescent chip: cutting the second hollow cylinder into a plurality of annular sheets, and then sintering to obtain a fluorescent chip; encapsulating the fluorescent chip: performing an encapsulation treatment on the fluorescent chip to obtain a wavelength conversion device. The reflective layer realizes the improvement of the luminous efficiency and the tolerance limit of the blue light power of the wavelength conversion device.

Description

Technical Field

[0001] This solution belongs to the field of lighting technology, and particularly relates to a wavelength conversion device and a preparation method thereof. Background Art

[0002] The wavelength conversion materials used in the field of laser lighting are usually organic silicone fluorescence systems. Based on the advantages of high brightness and relatively simple preparation process, organic silicone fluorescent materials have become the mainstream technology for wavelength conversion devices in current laser lighting sources. However, as laser light sources develop towards higher power and higher brightness, the problems of poor heat conduction and heat dissipation of organic fluorescent materials, yellowing of the fluorescent layer due to heat during long-term use, and decline in efficiency gradually emerge. Ceramic fluorescent materials, based on the advantages of high thermal conductivity, high heat resistance, and good heat dissipation, have become wavelength conversion materials with great application prospects. The prior art uses silver with high thermal conductivity as the fluorescent reflection layer of ceramic fluorescent materials, and then welds it to a high thermal conductivity substrate. The made ceramic fluorescent materials have the problem of low light efficiency utilization. Based on this, it is necessary to improve the luminous efficiency of ceramic fluorescent materials. Summary of the Invention

[0003] This solution aims to overcome at least one defect in the prior art, and provides a preparation method of a wavelength conversion device, enabling the wavelength conversion device to simultaneously have high luminous efficiency, high ultimate laser power resistance, and excellent aging resistance.

[0004] To solve the above technical problems, the following technical solutions are adopted:

[0005] In the first aspect, a preparation method of a wavelength conversion device is provided, including the following steps:

[0006] Prepare fluorescent ceramics: Process the fluorescent ceramic material into a first hollow cylinder, cut the first hollow cylinder with the axial section as the boundary to form two or more fan-shaped columnar bodies with inner sides, outer sides, and cut surfaces, and polish the inner sides, outer sides, and cut surfaces of the fan-shaped columnar bodies;

[0007] Prepare a pre-bonding layer: Coat a reflective slurry on the inner sides, outer sides, and cut surfaces of each fan-shaped columnar body, and bake to obtain fan-shaped columnar bodies with pre-bonding layers on the inner sides, outer sides, and cut surfaces;

[0008] Assemble the fan-shaped columnar bodies: Assemble the fan-shaped columnar bodies with pre-bonding layers together, and pre-sinter to form a second hollow cylinder assembled and co-sintered by fan-shaped columnar bodies with reflective layers on all four sides;

[0009] Prepare a fluorescent chip: Cut the second hollow cylinder along the direction perpendicular to the axis to form a plurality of annular sheets, and then sinter to obtain a fluorescent chip;

[0010] Package the fluorescent chip: Perform packaging treatment on the fluorescent chip to obtain a wavelength conversion device.

[0011] In this solution, the fluorescent ceramic material is first processed into a sector-ring column, and then a reflective slurry is coated on the inner side, outer side and cut surface of the sector-ring column, baked, and then assembled and co-fired. During the co-firing process, the reflective layers formed by the curing of the reflective slurry between two adjacent sector-ring columns are fused with each other, realizing the bonding of the cut surfaces of the sector-ring columns in pairs. Thus, a second hollow cylinder formed by assembling and co-firing sector-ring columns with reflective layers on all four sides is formed. The two adjacent sector-ring columns have a certain bonding strength, which is convenient for overall cutting. Then, cutting is carried out to obtain a ring-shaped sheet, which is integrally obtained by assembling several sector-ring-shaped sheets, and then sintered to obtain a fluorescent chip with very strong bonding. For the fluorescent chip, since the two adjacent sector-ring-shaped sheets are very firmly bonded, during use, laser can be prevented from hitting the reflective layer (such as a silver-plated layer or a sintered silver layer, etc.) of the heat dissipation substrate from the splicing position of the two adjacent sector-ring-shaped sheets, resulting in the burning of the thin reflective layer. Therefore, the finally prepared wavelength conversion device can withstand a high blue light power and has a high limit luminous flux. At the same time, the reflective layer plays a reflective role on the inner side, outer side and cut surface of the sector-ring-shaped sheet, which can improve the fluorescence collection efficiency, and the light efficiency can be comparable to that of a silica gel fluorescent color wheel. The two functions of bonding and reflection played by the reflective layer enable the finally prepared wavelength conversion device to achieve a higher limit luminous flux and luminous efficiency. In addition, this method can also facilitate mass production, facilitate the sequential preparation of more fluorescent chips, and improve production efficiency.

[0012] In addition, if the wavelength conversion device is made into a selectively light-emitting structure, that is, the wavelength conversion device does not perform continuous rotational motion, but can be selectively located on the laser light path, this structure can also prevent the emitted light from spilling into adjacent sector-ring-shaped sheets and generating stray light, which is beneficial to improving the purity of the emitted light.

[0013] Preferably, in the step of preparing the fluorescent ceramic, sector-ring columns of different materials are prepared by using different fluorescent ceramic materials; correspondingly, in the step of preparing the assembled sector-ring columns, sector-ring columns of different materials are assembled and co-fired.

[0014] More preferably, in the step of preparing the fluorescent ceramic, sector-ring columns of the first color, the second color and the third color are prepared by using fluorescent ceramic materials of the first color, the second color and the third color respectively; correspondingly, in the step of assembling the sector-ring columns, sector-ring columns of the first color, the second color and the third color are assembled and co-fired to form a second hollow cylinder with three-color splicing. For example, the first-color fluorescent ceramic material can use yellow fluorescent powder particles, the second-color fluorescent ceramic material can use green fluorescent powder particles, and the third-color fluorescent ceramic material can use red fluorescent powder particles.

[0015] Preferably, in the step of preparing the fluorescent ceramic, the polishing treatment makes the surface roughness of the inner side, outer side and cut surface of the sector-ring column satisfy Ra≤0.5μm.

[0016] Optionally, in the step of assembling the sector-ring column, the reflective layer is a sintered silver layer, which is obtained by sintering 0.3-3wt% glass powder particles and the balance silver powder particles, the reflective paste is silver paste, and the silver paste includes glass powder particles, silver powder particles and organic solvents.

[0017] Preferably, in the step of preparing the pre-bonding layer, the baking conditions are: baking at 120±10°C for 30±5min.

[0018] Preferably, in the step of assembling the sector-ring column, the pre-sintering conditions are: pre-sintering at 700±50°C for 30±5min.

[0019] Preferably, in the step of preparing the fluorescent chip, after cutting into multiple annular sheets, sintering at 900±50°C for 30±5min to obtain the fluorescent chip. This sintering method is applicable to the scheme where the reflection substrate bonded by silica gel is silver-plated reflective aluminum or the bottom of the fluorescent chip is coated with a metal oxide diffuse reflection layer. Or, after cutting into multiple annular sheets, coating silver paste on the bottom of the annular sheets, baking at 120±10°C for 30±5min, and then sintering at 900±50°C for 30±5min to obtain a fluorescent chip with a sintered silver layer on the bottom. This sintering method is applicable to the scheme of sintering silver on the bottom of the fluorescent chip.

[0020] Preferably, in the step of assembling the sector-ring column: the thickness of the sintered silver layer is 5-15μm; the glass powder particles are Zn / B / Si / K / O series glass powder; the softening temperature of the glass powder particles is 600-750°C; the particle size of the glass powder particles is 2-5μm; the particle size D50 of the silver powder particles is 0.3-5μm.

[0021] Optionally, in the step of assembling the sector-ring column, the reflective layer can also be a diffuse reflection layer, and the thickness of the diffuse reflection layer is 50-80μm.

[0022] Preferably, the step of encapsulating the fluorescent chip is specifically:

[0023] Bonding silver-plated reflective aluminum to the bottom of the fluorescent chip through transparent glue (silica gel); or coating a metal oxide diffuse reflection layer on the bottom of the fluorescent chip and then bonding a heat dissipation substrate; or sintering silver on the surface of the heat dissipation substrate and then welding the fluorescent chip with a sintered silver layer on the bottom to the surface of the heat dissipation substrate.

[0024] Second aspect, a wavelength conversion device prepared by the above method is provided. Specifically, the wavelength conversion device includes a fluorescent chip, a glue layer, and a silver-plated reflective aluminum layer stacked in sequence; or, the wavelength conversion device includes a fluorescent chip, a metal oxide diffuse reflection layer, and a heat dissipation substrate stacked in sequence; or, the wavelength conversion device includes a fluorescent chip, a sintered silver reflective layer, a solder layer, a sintered silver reflective layer, and a heat dissipation substrate stacked in sequence.

[0025] The beneficial effects of this solution compared with the prior art are as follows: In this solution, the fluorescent ceramic material is first processed into a sector-ring column with pre-bonding layers on the inner side, outer side, and cut surface, and then assembled and co-fired. During the sintering process, the pre-bonding layer forms a reflective layer, and the reflective layers between adjacent two sector-ring columns are fused with each other, realizing the bonding of the sector-ring columns in pairs. The adjacent sector-ring columns of the circular columns have a certain bonding strength, which is convenient for overall cutting. After cutting into circular sheets, sintering is carried out again to obtain a fluorescent chip with very firm bonding, so that the finally prepared wavelength conversion device can withstand high blue light power. Combining the reflection function of the reflective layer on the inner side, outer side, and cut surface of the sector-ring sheet, the finally prepared wavelength conversion device can improve the luminous efficiency and is suitable for mass production with high production efficiency. Description of the Drawings

[0026] The drawings are only for illustrative purposes and should not be construed as limitations to this solution; for better illustration of this solution, some components in the drawings will be omitted, enlarged or reduced, which do not represent the dimensions of the actual product; for those skilled in the art, it is understandable that some well-known structures and their descriptions in the drawings may be omitted.

[0027] Figure 1 It is an action decomposition diagram of the preparation method of the wavelength conversion device.

[0028] Description of the reference numerals: The first hollow cylinder 110, the sector-ring column 120, the inner side 121, the outer side 122, the cut surface 123, the reflective paste 210, the reflective layer 220, the second hollow cylinder 310, the fluorescent chip 320. Detailed Embodiments

[0029] The preparation method of the wavelength conversion device proposed in this solution includes the steps of preparing the fluorescent ceramic, preparing the pre-bonding layer, assembling the sector-ring columns, preparing the fluorescent chip, and encapsulating the fluorescent chip. The specific content of each step will be described in detail below.

[0030] I. Preparation of the fluorescent ceramic

[0031] Please refer to Figure 1(I-II), process the fluorescent ceramic material into a first hollow cylinder 110, and cut the first hollow cylinder 110 with the axial section as the boundary to form two or more (the "two or more" described in this article includes two) sector ring cylinders 120 having an inner side 121, an outer side 122 and a cut surface 123, and polish the inner side 121, the outer side 122 and the cut surface 123 of the sector ring cylinder 120.

[0032] The fluorescent ceramic material can be a pure fluorescent ceramic or a composite fluorescent ceramic sintered from fluorescent particles and metal oxide particles. This solution preferably uses a composite fluorescent ceramic, in which the mass ratio of the fluorescent particles to the metal oxide particles is (0.3-4):1. The fluorescent particles can be (Y,Gd)3(Al,Ga)5O 12 :Ce, α-Sialon:Eu system yellow phosphor particles, LuAG, GaYAG, β-Sialon:Eu and other green phosphor particles, and CaAlSiN3:Eu red phosphor particles, which are sintered by mixing one or more of them, and the particle shape is preferably spherical or quasi-spherical. The metal oxide particles can be one or more of alumina, magnesia, yttrium oxide, yttrium aluminum garnet, and magnesium aluminum spinel, preferably alumina, and the shape is preferably spherical or quasi-spherical.

[0033] The preparation of the composite fluorescent ceramic includes the following steps:

[0034] 1. Pulp making: Weigh the above-mentioned fluorescent particles and metal oxide particles according to a set ratio, add a certain mass of anhydrous ethanol solvent, introduce them into a ball mill tank dispersion device, and perform ball milling and dispersion for 6-12 h to obtain a mixed fluorescent slurry in which the fluorescent particle phase and the metal oxide particle phase are uniformly dispersed.

[0035] 2. Powder making: Dry the above-mentioned mixed fluorescent slurry at a temperature of 80±5°C for 8-24 h to remove the anhydrous ethanol solvent in the slurry; then introduce it into a mortar and grind it by hand so that the powder agglomerates are ground into fine powders, and after passing through a sieve, a uniformly dispersed mixed fluorescent powder is obtained.

[0036] 3. Sintering: Introduce the above-mentioned mixed fluorescent powder into a graphite mold, and use the SPS spark plasma sintering process with simultaneous pressurization and heating to set the sintering temperature, the applied pressure and the sintering time to obtain a composite fluorescent ceramic material with a hollow cylinder structure.

[0037] A hollow cylinder refers to a cylinder from which the central part has been cut off by coaxial cylindrical surfaces. An axial section refers to a section passing through the axis of the cylinder. A sector-annular column refers to a column whose cross-section formed by dividing the hollow cylinder by an axial section is sector-annular. The inner side surface of the sector-annular column is the inner wall of the hollow cylinder, its outer side surface is the outer wall of the hollow cylinder, and its cut surface coincides with the axial section that divides the hollow cylinder. After polishing, the surface roughness of the inner side surface, outer side surface, and cut surface of the sector-annular column satisfies Ra ≤ 0.5 μm.

[0038] II. Preparation of the pre-bonding layer

[0039] Please refer to Figure 1 (II~Ⅲ), apply the reflective slurry 210 on the inner side surface 121, outer side surface 122, and cut surface 123 of each sector-annular column 120, and bake to obtain the sector-annular column 120 with the pre-bonding layer 220 on the inner side surface 121, outer side surface 122, and cut surface 123.

[0040] Most of the organic solvents in the reflective slurry are removed during the baking process to form the pre-bonding layer. The pre-bonding layer is sintered subsequently to obtain the reflective layer 220. The pre-bonding layer facilitates the reflective layer of each sector-annular column to maintain a specific thickness and also facilitates fitting together and co-sintering.

[0041] The reflective layer can be a diffuse reflection layer formed by metal oxide diffuse reflection particles or a sintered silver layer formed by silver powder particles and glass powder particles. They can both be formed on the inner side surface, outer side surface, and cut surface of the sector-annular column through sintering, playing a role in reflection, improving the fluorescence collection efficiency, and the light efficiency can be comparable to that of organic fluorescent glue. The sintered silver layer is mainly composed of silver powder particles and glass powder particles, where the mass ratio of the glass powder is 0.3 - 3%, and the thickness of the silver layer is 5 - 15 μm. The particle size of the silver powder particles is preferably D50 = 0.3 - 5 μm, the glass powder particles preferably adopt the Zn / B / Si / K / O system, the softening temperature is preferably 600 - 750 °C, and the particle size is preferably 2 - 5 μm. The silver powder particles and glass powder particles are dispersed in an organic solvent (such as terpineol) to form silver paste for coating on the inner side surface, outer side surface, and cut surface of the sector-annular column. When coating the silver paste, the steel mesh printing process can be used to control the viscosity of the silver paste, screen parameters, and printing process to make the thickness of the silver layer 5 - 15 μm.

[0042] The reflective layer is preferably a sintered silver layer. If the reflective layer is a sintered silver layer, the reflective slurry is silver paste. For the sintered silver layer, during the subsequent sintering process, the silver powder particles and glass powder particles are sintered simultaneously to form a sintered silver layer firmly bonded to the sector-annular column. For the silver paste, the baking conditions are: placed in a high-temperature oven and baked at a temperature of 120 ± 10 °C for 30 ± 5 min to remove most of the organic solvents in the silver paste and form the pre-bonding layer.

[0043] III. Fitting together the sector-annular columns

[0044] Please refer to Figure 1 (III-IV), the sector-ring cylinders 120 with a pre-bonding layer 210 are assembled together and pre-sintered to form a second hollow cylinder 310 assembled and co-sintered by the sector-ring cylinders 120 each with a reflective layer 220 on four sides.

[0045] During the assembly and co-sintering process, the reflective layers formed by curing and sintering of the reflective paste between two adjacent sector-ring cylinders are fused with each other and sintered, realizing the pairwise bonding of the cut surfaces of the sector-ring cylinders, thereby forming a second hollow cylinder. The second hollow cylinder is formed by assembling and co-sintering the sector-ring cylinders each with a reflective layer on four sides. The two adjacent sector-ring cylinders have a certain bonding strength, which is convenient for subsequent overall cutting.

[0046] For the pre-bonding layer formed by silver paste, the pre-sintering conditions are: pre-sintering at 700±50°C for 30±5 min.

[0047] IV. Preparation of the fluorescent chip

[0048] Please refer to Figure 1 (IV-V) The second hollow cylinder 310 is cut along the direction perpendicular to the axis to form a plurality of annular sheets, and then sintered to obtain the fluorescent chip 320.

[0049] The second hollow cylinder can be cut into fluorescent chips with any thickness, and the specific thickness can be determined according to the actual requirements of the wavelength conversion device. This solution does not specifically limit the thickness value of the annular sheet. The thickness of the annular sheet set in the embodiment is only for experimental examples. When cutting the second hollow cylinder with a reflective layer, diamond multi-wire cutting can be used to improve the cutting speed. After cutting and then sintering, a fluorescent chip with very firm bonding can be obtained.

[0050] This technical solution uses a fluorescent ceramic as the fluorescent chip. Compared with wavelength conversion materials such as organic fluorescent materials, it can withstand higher blue light power, so the ultimate luminous flux is also higher. Since a reflective layer is provided on the side of the fluorescent chip, it can avoid the loss caused by light exiting from the side, and can greatly improve its luminous efficiency, making the luminous efficiency of the fluorescent chip comparable to that of organic fluorescent materials. Further, after cutting and then sintering, it is possible to achieve firm bonding of adjacent fan-shaped wafers in pairs without gaps, avoiding laser hitting the thin silver layer or other reflective layers below the fluorescent chip from the splicing joint of the two fan-shaped wafers, causing the thin silver layer or other reflective layers to be burned out. As a result, the finally produced wavelength conversion device can withstand higher blue light power than the splicing-type fluorescent ceramic wavelength conversion device without a reflective layer on the side, and the use reliability is also higher. In addition, if the wavelength conversion device is made into a structure with selective light output, that is, the wavelength conversion device does not perform continuous rotational motion but is selectively located on the laser light path, this structure can also avoid the emitted light from overflowing into adjacent fan-shaped wafers and generating stray light, which is beneficial to improving the purity of the emitted light.

[0051] For the sintered silver layer, after cutting into multiple annular wafers, it can be sintered at 900 ± 50 °C for 30 ± 5 min to obtain the fluorescent chip. This sintering method is applicable to the scheme of using silica gel to bond the reflective substrate to silver-plated reflective aluminum or coating the bottom of the fluorescent chip with a metal oxide diffusive reflection layer. Or, after cutting into multiple annular wafers, apply silver paste to the bottom of the annular wafers, bake at 120 ± 10 °C for 30 ± 5 min, and then sinter at 900 ± 50 °C for 30 ± 5 min to obtain a fluorescent chip with a sintered silver layer on the bottom. This sintering method is applicable to the scheme of sintering silver on the bottom of the fluorescent chip.

[0052] V. Encapsulating the fluorescent chip

[0053] Perform encapsulation treatment on the fluorescent chip to produce the wavelength conversion device.

[0054] The wavelength conversion device can be designed in a scheme where the bottom of the fluorescent chip is bonded to silver-plated reflective aluminum through transparent glue, or in a scheme where the bottom of the fluorescent chip is coated with a metal oxide diffusive reflection layer and then bonded to the heat dissipation substrate, or in a scheme where silver is sintered on the surface of the heat dissipation substrate and then the fluorescent chip with a sintered silver layer on the bottom is welded to the surface of the heat dissipation substrate.

[0055] The specific scheme of bonding the bottom of the fluorescent chip to silver-plated reflective aluminum through transparent glue is as follows: Use organic transparent silica gel to seal and bond the above-prepared fluorescent chip and silver-plated reflective aluminum, control the thickness of the glue layer, and then place it in a high-temperature oven at about 150 °C and bake for about 2 h to cure the bonding glue and produce the wavelength conversion device.

[0056] The specific solution for coating the bottom of the fluorescent chip with a metal oxide diffuse reflection layer and then bonding the heat dissipation substrate is as follows: Uniformly stir metal oxide particles such as alumina, magnesia, zinc oxide, titanium oxide, zirconia, lithopone, etc. with organic transparent silica gel to obtain a diffuse reflection slurry in which metal diffuse reflection particles are uniformly distributed in the organic transparent silica gel. Coat the diffuse reflection slurry on the surface of the metal aluminum substrate, and control the thickness of the diffuse reflection layer to be 50 - 80 um. Then, cover the above fluorescent chip on the surface of the diffuse reflection slurry, and place it in a high-temperature oven at about 150 °C for baking for about 4 h to cure the bonding glue, thus obtaining a wavelength conversion device.

[0057] The specific solution for sintering silver on the surface of the heat dissipation substrate and then welding the fluorescent chip with sintered silver at the bottom to the surface of the heat dissipation substrate is as follows: Prepare a slurry containing silver powder and glass powder, coat the slurry on the surface of the heat dissipation substrate, and fully sinter the heat dissipation substrate coated with the slurry at 900 ± 50 °C to form a sintered silver reflection layer. Finally, encapsulate the fluorescent chip with sintered silver at the bottom and the heat dissipation substrate with sintered silver on the surface together by means of reflow welding.

[0058] In the above-mentioned fluorescent chip, it can be designed into a multi-color splicing scheme, especially a yellow-green-red three-color splicing scheme, which can improve the color rendering index and color gamut.

[0059] To enable those skilled in the art to better understand this solution, the following further elaborates on this solution in combination with specific embodiments. The process methods used in the embodiments are all conventional methods unless otherwise specified; the materials used are all commercially available unless otherwise specified.

[0060] Example 1

[0061] The wavelength conversion device of this example includes a fluorescent chip, a glue layer, and a silver-plated reflective aluminum stacked in sequence, and its preparation method includes the following steps:

[0062] S1. Select (Y,Gd)3(Al,Ga)5O respectively 12:The composite fluorescent ceramic materials formed by the composite of Ce yellow phosphor particles and alumina (the mass ratio of yellow phosphor particles to alumina is 1:1), the composite fluorescent ceramic materials formed by the composite of LuAG green phosphor particles and alumina (the mass ratio of green phosphor particles to alumina is 1:1), and the composite fluorescent ceramic materials formed by the composite of CaAlSiN3:Eu red phosphor particles and alumina (the mass ratio of red phosphor particles to alumina is 0.3:1) are processed into three first hollow cylinders of yellow, green, and red. Each first hollow cylinder is cut with the axial section as the boundary, and the first hollow cylinder of yellow fluorescent ceramic, the first hollow cylinder of green fluorescent ceramic, and the first hollow cylinder of red fluorescent ceramic are respectively formed into three sector ring cylinders with central angles of 120°, 180°, and 60°. The inner side, outer side, and cut surface of each sector ring cylinder are polished so that the surface roughness Ra≤0.5μm.

[0063] S2. Weigh glass powder particles and silver powder particles according to the mass ratio of glass powder particles to silver powder particles of 1:99. Among them, the glass powder selects the Zn / B / Si / O system, the softening temperature is about 700°C, and the particle size is 2 - 5μm. The particle size of the silver powder particles D50 = 0.8 - 1.6μm. They are dispersed in terpineol to form a silver paste. Using the steel mesh printing process, the silver paste is coated on the inner side, outer side, and cut surface of each sector ring cylinder. Control the viscosity of the silver paste, the screen parameters, and the printing process to make the thickness of the silver paste about 10μm. The sector ring cylinder coated with the silver paste is placed in a high-temperature oven and baked at 120°C for 30min to remove most of the terpineol in the silver paste.

[0064] S3. Then the three baked sector ring cylinders of yellow, green, and red are assembled and placed in a high-temperature sintering furnace, and pre-sintered at about 700°C for about 30min to form a second hollow cylinder assembled and co-fired.

[0065] S4. Using the multi-wire cutting method, the second hollow cylinder is cut along the direction perpendicular to the axis to form a plurality of annular sheets, and an annular sheet with a thickness of 150μm formed by splicing three sector-shaped sheets of yellow, green, and red is obtained. It is placed in a high-temperature sintering furnace and sintered at about 900°C for about 30min to obtain a fluorescent chip with three-color splicing and a sintered silver layer.

[0066] S5. Using organic transparent silicone, the fluorescent chip is sealed with silver-plated reflective aluminum. Control the thickness of the glue layer, and then place it in a high-temperature oven and bake at 150°C for 2h to make the bonding glue cured, thus obtaining the wavelength conversion device.

[0067] Example 2

[0068] The wavelength conversion device of this example includes a fluorescent chip, a first silver layer, a solder layer, a second silver layer, and an aluminum heat dissipation substrate stacked in sequence. Its preparation method includes the following steps:

[0069] S1. Select (Y,Gd)3(Al,Ga)5O 12 :Ce yellow phosphor particles and alumina composite to form a composite phosphor ceramic material (the mass ratio of yellow phosphor particles to alumina is 1:1), LuAG green phosphor particles and alumina composite to form a composite phosphor ceramic material (the mass ratio of green phosphor particles to alumina is 1:1), and CaAlSiN3:Eu red phosphor particles and alumina (the mass ratio of red phosphor particles to alumina is 0.3:1) composite to form a composite phosphor ceramic material, and process and form three first hollow cylinders of yellow, green, and red. Cut each first hollow cylinder with the axial section as the boundary. The first hollow cylinder of yellow phosphor ceramic, the first hollow cylinder of green phosphor ceramic, and the first hollow cylinder of red phosphor ceramic respectively form three sector ring cylinders with central angles of 120°, 180°, and 60°. Polish the inner side, outer side, and cut surface of each sector ring cylinder so that the surface roughness Ra ≤ 0.5 μm.

[0070] S2. Weigh glass powder particles and silver powder particles according to the mass ratio of glass powder particles to silver powder particles of 1:99. Among them, the glass powder selects the Zn / B / Si / O system, the softening temperature is about 700 °C, and the particle size is 2 - 5 μm. The particle size of the silver powder particles D50 = 0.8 - 1.6 μm, and disperse them in terpineol to form silver paste; adopt the steel mesh printing process, coat the silver paste on the inner side, outer side, and cut surface of each sector ring cylinder, control the viscosity of the silver paste, screen parameters, and printing process so that the thickness of the silver paste is about 10 μm; put the sector ring cylinder coated with silver paste into a high-temperature oven and bake at 120 °C for 30 min to remove most of the terpineol in the silver paste.

[0071] S3. Then assemble the baked sector ring cylinders of yellow, green, and red, put them into a high-temperature sintering furnace, and pre-sinter at about 700 °C for about 30 min to form a second hollow cylinder assembled and co-sintered.

[0072] S4. Adopt the multi-wire cutting method to cut the second hollow cylinder along the direction perpendicular to the axis to form multiple annular sheets, and obtain an annular sheet with a thickness of 150 μm assembled by yellow, green, and red sector-shaped sheets. Coat silver paste on the bottom of the annular sheet, bake at 120 ± 10 °C for 30 ± 5 min, and then sinter at 900 ± 50 °C for 30 ± 5 min to obtain a fluorescent chip with a first silver layer coated on the bottom.

[0073] S5. Also coat silver paste on the surface of the aluminum heat dissipation substrate, sinter it fully at 900 ± 50 °C to form a second silver layer on the aluminum heat dissipation substrate, and finally encapsulate the fluorescent chip with the first silver layer coated on the bottom and the aluminum heat dissipation substrate with the second silver layer coated on the surface together by the reflow welding method.

[0074] Comparative Example 1

[0075] A wavelength conversion device, comprising a fluorescent chip, a glue layer, and a silver-plated reflective aluminum layer stacked in sequence, and a preparation method thereof includes the following steps:

[0076] S1. Respectively select a composite fluorescent ceramic material formed by (Y,Gd)3(Al,Ga)5O 12 :Ce yellow phosphor particles and alumina (the mass ratio of yellow phosphor particles to alumina is 1:1), a composite fluorescent ceramic material formed by LuAG green phosphor particles and alumina (the mass ratio of green phosphor particles to alumina is 1:1), and a composite fluorescent ceramic material formed by CaAlSiN3:Eu red phosphor particles and alumina (the mass ratio of red phosphor particles to alumina is 0.3:1) to process and form three hollow cylinders of yellow, green, and red. Cut each hollow cylinder with the axial section as the boundary, and the yellow fluorescent ceramic hollow cylinder, the green fluorescent ceramic hollow cylinder, and the red fluorescent ceramic hollow cylinder respectively form three fan-shaped columnar bodies with central angles of 120°, 180°, and 60°.

[0077] S2. Adopt a multi-wire cutting method to slice the fan-shaped columnar body along the direction perpendicular to the axis to obtain a fan-shaped sheet with a thickness of 150 μm, and splice the yellow, green, and red fan-shaped sheets into a circular fluorescent chip.

[0078] S3. Use organic transparent silica gel to seal the fluorescent chip and the silver-plated reflective aluminum, control the thickness of the glue layer, and then put it into a high-temperature oven and bake at 150 °C for 2 h to cure the bonding glue, thereby obtaining the wavelength conversion device.

[0079] Comparative Example 2

[0080] A wavelength conversion device, comprising a fluorescent chip, a glue layer, and a silver-plated reflective aluminum layer stacked in sequence, and a preparation method thereof includes the following steps:

[0081] S1. Respectively select a composite fluorescent ceramic material formed by (Y,Gd)3(Al,Ga)5O 12:A composite fluorescent ceramic material formed by the combination of Ce yellow phosphor particles and alumina (the mass ratio of yellow phosphor particles to alumina is 1:1), a composite fluorescent ceramic material formed by the combination of LuAG green phosphor particles and alumina (the mass ratio of green phosphor particles to alumina is 1:1), and a composite fluorescent ceramic material formed by the combination of CaAlSiN3:Eu red phosphor particles and alumina (the mass ratio of red phosphor particles to alumina is 0.3:1) are processed into yellow, green, and red hollow cylinders. Each hollow cylinder is cut along the axial section. The yellow fluorescent ceramic hollow cylinder, the green fluorescent ceramic hollow cylinder, and the red fluorescent ceramic hollow cylinder respectively form three sector ring cylinders with central angles of 120°, 180°, and 60°. The inner side, outer side, and cut surface of each sector ring cylinder are polished so that the surface roughness Ra ≤ 0.5 μm.

[0082] S2. Weigh glass powder particles and silver powder particles according to the mass ratio of glass powder particles to silver powder particles of 1:99. Among them, the glass powder selects the Zn / B / Si / O system, has a softening temperature of about 700 °C, and a particle size of 2 - 5 μm. The particle size of the silver powder particles D50 = 0.8 - 1.6 μm. They are dispersed in terpineol to form a silver paste. Using the steel screen printing process, the silver paste is coated on the inner side, outer side, and cut surface of each sector ring cylinder. Control the viscosity of the silver paste, screen parameters, and printing process so that the thickness of the silver paste is about 10 μm. The sector ring cylinder coated with the silver paste is placed in a high-temperature oven and baked at 120 °C for 30 min to remove most of the terpineol in the silver paste.

[0083] S3. The baked yellow, green, and red sector ring cylinders are placed in a high-temperature sintering furnace and sintered at about 900 °C for about 30 min to form sector ring cylinders with a sintered silver layer.

[0084] S4. Using the multi-wire cutting method, the sector ring cylinder with a sintered silver layer is sliced along the direction perpendicular to the axis to obtain a sector ring-shaped sheet with a thickness of 150 μm. The yellow, green, and red sector ring-shaped sheets are assembled into a circular fluorescent chip.

[0085] S5. Using organic transparent silicone, the fluorescent chip is sealed with silver-plated reflective aluminum. Control the thickness of the glue layer, and then place it in a high-temperature oven and bake at 150 °C for 2 h to make the bonding glue cure, thus obtaining a wavelength conversion device.

[0086] The wavelength conversion devices prepared in Example 1, Example 2, Comparative Example 1, and Comparative Example 2 are assembled on a laser light source system for testing. The laser light source system uses a blue laser source with a maximum blue light output power of 80 W and a laser spot size of Φ1.2 mm. The test items include: the blue light power limit value and limit luminous flux of the wavelength conversion device, the luminous flux at a low blue light power of 4 w, and the high and low temperature cycle test.

[0087] (1) Test of the blue light power limit value and the limit luminous flux: Install the wavelength conversion devices in the embodiments 1 and 2 of this case, and the comparative examples 1 and 2 into the light source system respectively. As the blue light power increases, when the luminous flux no longer rises or even decreases, the power at this time is the blue light power limit value of the wavelength conversion device. The luminous flux measured at the limit blue light power is the limit luminous flux value of the wavelength conversion device.

[0088] (2) Test of the luminous flux at a 4W blue light power: Install the wavelength conversion devices in the embodiments 1 and 2 of this case, and the comparative examples 1 and 2 into the above light source system respectively, and test the luminous flux at a blue light power of 4W, a test distance of 10m and an imaging lens of 130mm to evaluate the luminous efficiency of the wavelength conversion device.

[0089] (3) High and low temperature cycle test: Test the change in the luminous flux of the wavelength conversion devices before and after high and low temperature aging in the above embodiments 1, 2, comparative example 1 and comparative example 2. When the luminous flux after aging drops to less than 90% of that before aging, it is the tolerable limit aging duration, and calculate the number of cycles to evaluate its reliability. High and low temperature test environment: high temperature 85°C, low temperature -40°C. One cycle is 2h.

[0090] The test results are shown in Table 1 below.

[0091] Table 1

[0092] Test item Blue light resistance power limit value / w Limit luminous flux / lm 4w luminous flux / lm Number of high and low temperature cycle resistances Example 1 62 11262 786 Above 1000 Example 2 66 11328 722 Above 1000 Comparative example 1 54 8688 663 650 Comparative example 2 58 10356 779 650

[0093] As can be seen from Table 1, the blue light power limit values of both Embodiment 1 and Embodiment 2 reach above 62W, the limit luminous fluxes reach above 11262lm, the 4W luminous fluxes reach above 722lm, and the high and low temperature cycle numbers reach above 1000, indicating that the finally obtained wavelength conversion device can withstand high blue light power, has a high limit luminous flux, high luminous efficiency, stable performance and good reliability.

[0094] Comparing Embodiment 1 with Comparative Examples 1 and 2, it can be seen that for the wavelength conversion device where the adjacent fan-shaped ring cylinders are not adhesively bonded to each other through a reflective layer, the blue light power limit value, the limit luminous flux, the 4W luminous flux and the high and low temperature cycle number all decrease. This is because there are gaps at the joints of the adjacent fan-shaped ring cylinders in Comparative Examples 1 and 2 and they are not adhesively bonded to each other through a reflective layer, and the blue laser passes through these gaps and hits the silver-plated layer below the fluorescent chip, causing the silver-plated layer to be burned out, so it cannot withstand higher blue light power and the reliability of use is also greatly reduced; in Comparative Example 1, since there is no reflective layer on all four sides of each fan-shaped sheet to play a reflective role, the limit luminous flux and the luminous efficiency also decrease significantly.

[0095] Obviously, the above embodiments of the present solution are merely examples for clearly illustrating the present solution, rather than limitations on the implementation manners of the present solution. For those of ordinary skill in the art, other different forms of changes or alterations can be made based on the above description. It is not necessary and impossible to enumerate all the implementation manners here. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principle of the present solution shall be included within the protection scope of the claims of the present solution.

Claims

1. A method for preparing a wavelength conversion device, characterized in that: The steps include: Preparation of fluorescent ceramics: forming the fluorescent ceramic material into a first hollow cylinder, cutting the first hollow cylinder with the axial section as the boundary to form two or more sector ring cylinders having inner side surfaces, outer side surfaces and cut surfaces, and polishing the inner side surfaces, outer side surfaces and cut surfaces of the sector ring cylinders; Preparation of pre-bonding layer: coating the inner side, outer side and cut surface of each fan ring column with a reflective slurry, and baking the coating to obtain a fan ring column having a pre-bonding layer on the inner side, outer side and cut surface; Splicing the sector ring cylinders: Splicing the sector ring cylinders with pre-bonding layers together and pre-sintering them to form a second hollow cylinder composed of the sector ring cylinders with reflective layers on all four sides and co-fired; Preparing a fluorescent chip: cutting the second hollow cylinder in a direction perpendicular to the axial direction to form a plurality of annular slices, and then sintering them to obtain a fluorescent chip; Encapsulating the fluorescent chip: Encapsulating the fluorescent chip to obtain the wavelength conversion device.

2. The method for preparing a wavelength conversion device according to claim 1, wherein: In the step of preparing the fluorescent ceramic, different fluorescent ceramic materials are used to prepare fan ring columns of different materials; in the step of splicing the fan ring columns, fan ring columns of different materials are spliced and co-fired.

3. The method for preparing a wavelength conversion device according to claim 2, wherein: In the step of preparing the fluorescent ceramic, fluorescent ceramic materials of the first color, the second color and the third color are respectively used to make fan-ring cylinders of the first color, the second color and the third color; in the step of splicing the fan-ring cylinders, the fan-ring cylinders of the first color, the second color and the third color are spliced and co-fired to form a second hollow cylinder spliced with three colors.

4. The method for preparing a wavelength conversion device according to claim 1, wherein: In the step of preparing the fluorescent ceramic, the polishing process is performed so that the surface roughness of the inner side surface, the outer side surface and the cut surface of the sector ring cylinder meets Ra≤0.5μm.

5. The method for preparing a wavelength conversion device according to any one of claims 1 to 4, characterized in that: In the step of assembling the fan ring cylinder, the reflective layer is a sintered silver layer, which is obtained by sintering 0.3-3wt% glass powder particles and the remaining silver powder particles. The reflective slurry is a silver paste, which includes glass powder particles, silver powder particles and an organic solvent.

6. The method for preparing a wavelength conversion device according to claim 5, wherein: In the step of preparing the pre-bonding layer, the baking conditions are: baking at 120±10°C for 30±5min; In the step of assembling the fan ring cylinder, the pre-sintering conditions are: 700±50°C for 30±5min; In the step of preparing the fluorescent chip, after cutting to form multiple annular pieces, the sintering conditions are: sintering at 900±50°C for 30±5 minutes; or after cutting to form multiple annular pieces, the sintering conditions are: coating silver paste on the bottom of the annular piece, baking at 120±10°C for 30±5 minutes, and then sintering at 900±50°C for 30±5 minutes, to obtain a fluorescent chip with sintered silver coated on the bottom.

7. The method for preparing a wavelength conversion device according to claim 5, wherein: In the step of assembling the fan ring cylinder: The thickness of the sintered silver layer is 5 to 15 μm; and / or The glass powder particles are Zn / B / Si / K / O series glass powder; and / or The softening temperature of the glass powder particles is 600-750° C.; and / or The particle size of the glass powder particles is 2 to 5 μm; and / or The particle size D50 of the silver powder particles is 0.3 to 5 μm.

8. The method for preparing a wavelength conversion device according to any one of claims 1 to 4, characterized in that: In the step of assembling the sector ring cylinder, the reflective layer is a diffuse reflective layer, and the thickness of the diffuse reflective layer is 50 to 80 μm.

9. The method for preparing a wavelength conversion device according to any one of claims 1 to 4, characterized in that: The steps of packaging the fluorescent chip are specifically as follows: Adhere silver-plated reflective aluminum to the bottom of the fluorescent chip using transparent glue; or Applying a metal oxide diffuse reflection layer on the bottom of the fluorescent chip and then bonding a heat dissipation substrate thereto; or Silver is sintered on the surface of the heat dissipation substrate, and then the phosphor chip with the bottom covered with sintered silver is soldered to the surface of the heat dissipation substrate.

10. A wavelength conversion device prepared by the method according to any one of claims 1 to 9.

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