WO2022037317A1 - 波长转换装置及其制备方法 - Google Patents

波长转换装置及其制备方法 Download PDF

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Publication number
WO2022037317A1
WO2022037317A1 PCT/CN2021/105907 CN2021105907W WO2022037317A1 WO 2022037317 A1 WO2022037317 A1 WO 2022037317A1 CN 2021105907 W CN2021105907 W CN 2021105907W WO 2022037317 A1 WO2022037317 A1 WO 2022037317A1
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layer
silver
light
wavelength conversion
conversion device
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PCT/CN2021/105907
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English (en)
French (fr)
Inventor
李乾
田梓峰
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深圳市绎立锐光科技开发有限公司
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Priority to US18/022,073 priority Critical patent/US20230369544A1/en
Priority to EP21857412.7A priority patent/EP4194947A4/en
Publication of WO2022037317A1 publication Critical patent/WO2022037317A1/zh

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    • G—PHYSICS
    • G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
    • G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
    • G03B21/00—Projectors or projection-type viewers; Accessories therefor
    • G03B21/14—Details
    • G03B21/20—Lamp housings
    • G03B21/2006—Lamp housings characterised by the light source
    • G03B21/2033—LED or laser light sources
    • G03B21/204—LED or laser light sources using secondary light emission, e.g. luminescence or fluorescence
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21K—NON-ELECTRIC LIGHT SOURCES USING LUMINESCENCE; LIGHT SOURCES USING ELECTROCHEMILUMINESCENCE; LIGHT SOURCES USING CHARGES OF COMBUSTIBLE MATERIAL; LIGHT SOURCES USING SEMICONDUCTOR DEVICES AS LIGHT-GENERATING ELEMENTS; LIGHT SOURCES NOT OTHERWISE PROVIDED FOR
    • F21K9/00—Light sources using semiconductor devices as light-generating elements, e.g. using light-emitting diodes [LED] or lasers
    • F21K9/60—Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction
    • F21K9/64—Optical arrangements integrated in the light source, e.g. for improving the colour rendering index or the light extraction using wavelength conversion means distinct or spaced from the light-generating element, e.g. a remote phosphor layer
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
    • F21V9/30—Elements containing photoluminescent material distinct from or spaced from the light source
    • F21V9/32—Elements containing photoluminescent material distinct from or spaced from the light source characterised by the arrangement of the photoluminescent material
    • F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
    • F21—LIGHTING
    • F21V—FUNCTIONAL FEATURES OR DETAILS OF LIGHTING DEVICES OR SYSTEMS THEREOF; STRUCTURAL COMBINATIONS OF LIGHTING DEVICES WITH OTHER ARTICLES, NOT OTHERWISE PROVIDED FOR
    • F21V9/00—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters
    • F21V9/40—Elements for modifying spectral properties, polarisation or intensity of the light emitted, e.g. filters with provision for controlling spectral properties, e.g. colour, or intensity
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/44—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the coatings, e.g. passivation layer or anti-reflective coating
    • H01L33/46—Reflective coating, e.g. dielectric Bragg reflector
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/64—Heat extraction or cooling elements
    • H01L33/641—Heat extraction or cooling elements characterized by the materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L2933/00—Details relating to devices covered by the group H01L33/00 but not provided for in its subgroups
    • H01L2933/0008—Processes
    • H01L2933/0033—Processes relating to semiconductor body packages
    • H01L2933/0041—Processes relating to semiconductor body packages relating to wavelength conversion elements
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/501—Wavelength conversion elements characterised by the materials, e.g. binder
    • H01L33/502—Wavelength conversion materials
    • H—ELECTRICITY
    • H01—ELECTRIC ELEMENTS
    • H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
    • H01L33/00—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof
    • H01L33/48—Semiconductor devices having potential barriers specially adapted for light emission; Processes or apparatus specially adapted for the manufacture or treatment thereof or of parts thereof; Details thereof characterised by the semiconductor body packages
    • H01L33/50—Wavelength conversion elements
    • H01L33/507—Wavelength conversion elements the elements being in intimate contact with parts other than the semiconductor body or integrated with parts other than the semiconductor body

Definitions

  • the present invention relates to the technical field of lighting and projection, and in particular, to a wavelength conversion device, a preparation method thereof, and a light-emitting device using the wavelength conversion device.
  • the continuous laser irradiation makes the working environment of the wavelength conversion device very harsh; in order to withstand the continuous irradiation of the laser light, a large amount of heat generated by the light-emitting layer during the wavelength conversion process cannot be eliminated.
  • the problem of thermal quenching caused by the rapid increase of its own temperature, the host material of the light-emitting layer has been developed from traditional organic materials to inorganic materials such as glass and ceramics with better thermal conductivity and heat resistance.
  • the connection between the light-emitting layer and the substrate generally adopts a solder layer or a sintered silver layer.
  • the sintered silver layer has better thermal conductivity than the solder layer, but there are some problems, such as:
  • the organic solvent in the middle area of the organic silver paste is difficult to volatilize, and the nano-spherical silver particles are easily sintered to cause excessive shrinkage in size.
  • the sintered silver layer has problems such as decreased cohesion and easy falling off due to large and large stress. At the same time, more pores are formed during the sintering process, which reduces the contact area between the nano-spherical silver particles and reduces the thermal conductivity.
  • the present invention provides a wavelength conversion device with high overall device reliability, good thermal conductivity and heat dissipation performance, and high luminous efficiency and a preparation method thereof.
  • the wavelength conversion device can be suitable for continuous high-power laser irradiation. .
  • the invention provides a wavelength conversion device, comprising a light-emitting layer, a reflective film, a sintered silver layer and a substrate stacked in sequence; the light-emitting layer converts the excitation light into outgoing light of different wavelengths, and the reflective film is coated on the On the light-emitting layer, it is used to reflect the light emitted from the light-emitting layer; the sintered silver layer connects the light-emitting layer and the substrate, and the sintered silver layer is connected to each other through surface contact. Flake silver particles.
  • the nano-spherical silver particles are melted and the flaky silver particles are combined to form a sintered silver layer.
  • the large-sized flake silver particles in the sintered silver layer improve the shrinkage of the sintered silver paste, reduce the sintering stress, and improve the adhesion performance of the sintered silver layer; at the same time, the large-sized flake silver particles in the sintered silver layer are mutually They are connected by surface contact, and the large-sized flake silver particles themselves serve as heat conduction channels and the surface contact heat transfer between each other greatly improves the thermal conductivity of the sintered silver layer.
  • the thermal conductivity of the sintered silver layer is 80-250 W/(m ⁇ k).
  • the content of flaky silver particles in the sintered silver layer is 2-20wt%, preferably 5-15wt%, more preferably 7-10wt%.
  • the light-emitting layer is a light-emitting ceramic layer, and the light-emitting layer made of ceramic material has the characteristics of excellent heat resistance and thermal conductivity.
  • the reflective film is a silver reflective film
  • the silver reflective film has the characteristics of compactness and high reflectivity.
  • a transition layer is arranged between the luminescent ceramic layer and the silver reflective film, the transition layer enhances the bonding force between the luminescent ceramic layer and the silver reflective film, and the transition layer can be an Al 2 O 3 layer or a SiO layer 2 layers; in addition, between the luminescent ceramic layer and the silver reflective film, alternating layers of high-refractive-index dielectric films and low-refractive-index dielectric films sequentially stacked on the silver reflective film can also be arranged, such as high-refractive index dielectric films.
  • the entire film layer can not only play the role of increasing reflection, but also serve as a transition layer between the silver reflective film and the luminescent ceramic layer to enhance the Ag film and the luminous Bonding of ceramic layers.
  • an anti-diffusion layer is arranged between the silver reflective film and the sintered silver layer, and the anti-diffusion layer can be a Ni layer, mainly to prevent the diffusion of Ag atoms in the silver reflective film and ensure that the silver reflective film has sufficient Reflectivity.
  • the substrate may be a substrate with bearing capacity and high thermal conductivity, such as a metal or ceramic substrate.
  • copper metal as a substrate has very good thermal conductivity
  • ceramic substrates such as AlN or SiC are selected mainly to reduce the stress caused by the difference in thermal expansion coefficient between the luminescent ceramic layer and the metal substrate during thermal expansion and contraction. , so that the reliability of the wavelength conversion device is higher.
  • the thermal conductivity of ceramics is lower than that of copper substrates and the heat dissipation capacity is reduced, its high reliability can be applied to many high-precision light sources.
  • the present invention also provides a light-emitting device, comprising an excitation light source and the above-mentioned wavelength conversion device, and the light-emitting device is suitable for the fields of illumination and projection.
  • the present invention also provides a method for preparing a wavelength conversion device, comprising the following steps:
  • Step 1 preparing a light-emitting layer, and polishing the surface of the light-emitting layer
  • Step 2 forming a reflective film on the polished surface of the light-emitting layer through a physical sputtering or evaporation process
  • Step 3 apply the silver paste mixed with nano-spherical silver particles and flake silver particles on one surface of the substrate;
  • Step 4 superimpose the surface of the light-emitting layer coated with the reflective film on the surface of the substrate coated with the silver paste;
  • Step 5 Sinter the entire device.
  • the content of flake silver particles in the silver paste in step 3 is 2-20wt%, preferably 5-15wt%, more preferably 7-10wt%.
  • the light-emitting layer prepared in step 1 is a light-emitting ceramic layer.
  • the reflective film formed on the polished surface of the luminescent ceramic layer by a physical sputtering or evaporation process is a silver reflective film.
  • it also includes forming a transition layer on the polished surface of the luminescent ceramic layer by physical sputtering or evaporation, and the transition layer can be an Al 2 O 3 layer or a SiO 2 layer; further
  • it also includes alternating layers of a low-refractive-index dielectric film and a high-refractive-index dielectric film formed by physical sputtering or evaporation, which are sequentially laminated on the polished surface of the luminescent ceramic layer, such as a high-refractive-index dielectric film.
  • step 2 it also includes forming an anti-diffusion layer on the silver reflective film by physical sputtering or evaporation, and the anti-diffusion layer may be a metal Ni layer.
  • the substrate in step 3 is a metal substrate or a ceramic substrate
  • the metal substrate may be a copper metal substrate
  • the ceramic substrate may be an AlN or SiC substrate.
  • the present invention includes the following beneficial effects:
  • a sintered silver layer with extremely high thermal conductivity is used between the light-emitting layer and the heat dissipation substrate to connect and conduct. It is formed by the mixing and sintering of silver particles, and the melting of nano-spherical silver particles to combine large-sized flake silver particles.
  • the large-sized flake silver particles in the prepared sintered silver layer improve the shrinkage of the sintered silver paste, reduce the sintering stress, and improve the adhesion performance of the sintered silver layer; at the same time, the large-sized flake silver particles in the sintered silver layer are mutually They are in surface contact, and the large-sized silver particles themselves serve as heat conduction channels and the surface contact heat transfer between them can improve the thermal conductivity of the sintered silver layer.
  • FIG. 1 is a schematic structural diagram of a wavelength conversion device according to Embodiment 1 of the present invention.
  • FIG. 2 is a schematic structural diagram of a wavelength conversion device according to Embodiment 2 of the present invention.
  • FIG. 3 is a schematic structural diagram of a wavelength conversion device according to Embodiment 3 of the present invention.
  • FIG. 4 is a schematic structural diagram of the sintered silver layer of the present invention.
  • the current sintered silver is mainly used in small-sized packages in device packaging, and relatively few applications in areas larger than 4*4mm 2 .
  • the organic solvent in the middle area of sintered silver it is difficult for the organic solvent in the middle area of sintered silver to volatilize during the sintering process, and the nano-silver particles are likely to cause excessive shrinkage and large stress during sintering, which affects the packaging performance (such as decreased adhesion);
  • more pores are formed in the sintered silver layer, which reduces the contact area between the silver nanoparticles and reduces the thermal conductivity.
  • a sintered silver layer with excellent performance is prepared by mixing and sintering nano-silver particles and large-sized flake silver particles, and the sintered silver layer is applied as a heat-conducting bonding layer between a light-emitting layer and a substrate in a wavelength conversion device, thereby obtaining device reliability. High and good thermal conductivity wavelength conversion device.
  • the present invention provides a wavelength conversion device 100 , which includes a light-emitting layer 101 , a reflective film 102 , a sintered silver layer 103 and a substrate 104 that are stacked in sequence.
  • the light-emitting layer 101 converts the excitation light into outgoing light of different wavelengths
  • the reflective film 102 is coated on the light-emitting layer 101 to reflect the outgoing light from the light-emitting layer 101 ;
  • the sintered silver layer 103 connects the light-emitting layer 101 and the substrate 104 , the sintered silver layer 103 contains flake silver particles connected with each other through surface contact.
  • the light-emitting layer 101 is usually a light-emitting ceramic layer with good heat dissipation and heat resistance.
  • the light-emitting material that is, the wavelength conversion material
  • its composition is not particularly limited.
  • it can be aluminate phosphor, halophosphoric acid phosphor One of the phosphors, garnet-based phosphors or quantum dots.
  • the luminescent ceramic layer 101 may be a YAG pure-phase luminescent ceramic, or a complex-phase luminescent ceramic prepared by mixing YAG with Al 2 O 3 powder or AlN powder.
  • Al 2 O 3 can be used to encapsulate YAG:Ce phosphor powder to form a luminescent ceramic layer.
  • the thickness of the luminescent ceramic layer is about 50-250um when comprehensively considering luminous efficiency and thermal conductivity.
  • an anti-reflection film 101a may be disposed on the upper surface of the light-emitting layer 101 facing the incident light.
  • the anti-reflection film 101a can play the role of anti-reflection and anti-reflection, that is, reducing the reflectivity of the incident excitation light on the upper surface of the light-emitting layer 101 and increasing the transmittance of the excitation light on the light-emitting layer 101, which is beneficial to improve the light output on the surface of the light-emitting layer 101 effectiveness.
  • the thickness of the anti-reflection film 101a is preferably 0.01um ⁇ 0.1um.
  • the reflective film 102 coated on the light-emitting layer 101 may be a silver reflective film, which is generally coated on one surface of the light-emitting layer 101 by techniques such as physical sputtering or evaporation, and the obtained silver reflective film It has the characteristics of compactness and high reflectivity, and the thickness of the silver reflective film is preferably 10nm to 1um.
  • a transition layer 101b can be first plated on the luminescent ceramic layer, and then the silver reflective film is plated.
  • 101b can be an Al 2 O 3 layer or a SiO 2 layer; in addition, an alternating film of a low-refractive-index dielectric film and a high-refractive-index dielectric film that are sequentially stacked on the luminescent ceramic layer can also be arranged between the luminescent ceramic layer and the silver reflective film.
  • the entire film layer can not only play the role of increasing reflection, but also serve as a transition layer between the silver reflective film and the luminescent ceramic layer, enhancing the Combination of Ag film and luminescent ceramic layer.
  • the thickness of the transition layer 101b is about 10-200 nm.
  • a layer of anti-diffusion layer 102a can be plated on the silver reflective film and then connected to the sintered silver layer 103; the anti-diffusion layer 102a It can be a metal Ni layer with a thickness of about 10-500nm.
  • the sintered silver layer 103 of the present application is prepared by sintering nano-spherical silver particles and large-sized flake silver particles.
  • the radius of curvature of nano-spherical silver particles is relatively consistent in all directions, and it is easy to melt and flow during the sintering process; while large-sized flake silver particles are generally cuboid or flat, and their length in the length direction or flat direction is much larger than that in the sintering process.
  • the length in the thickness direction is not easy to melt during the sintering process, which prevents the material from shrinking excessively; in this way, during the sintering process, the large-sized flake silver particles support each other, and are melted and bonded by nano-spherical silver particles, and finally form a card containing a card
  • the sintered silver layer 103 of the large-sized flake silver particles in the bridge structure and in surface contact with each other has a larger contact area between the flake silver particles, which better forms a thermal conduction network.
  • the sintered silver layer 103 may be a structure in which flaky silver stacked between layers is bonded by molten silver, as shown in FIG. 4 , where 1 represents large-sized flaky silver particles, and 2 represents the melting point between them. Silver for connection.
  • the raw silver paste for sintering the silver layer is an organic silver paste mixed with nano-spherical silver particles and large-sized flake silver particles, which contains a small amount of organic solvent, and the content of flake silver particles is 2-20wt%, preferably 5-15 wt %, more preferably 7-10 wt %, the size of the flake silver particles is above the micron level.
  • the sintering activity is very small compared to the nano-spherical silver particles.
  • the nano-spherical silver particles are sintered and melted to bond and connect the flaky silver particles, and the content of the flaky silver particles in the formed sintered silver layer is almost unchanged.
  • the introduction of large-sized flake silver particles can well solve the problems of excessive size shrinkage and large stress of nano-spherical silver particles during the sintering process, and improve the bonding performance of the sintered silver layer;
  • the flaky silver particles are in surface contact, which can greatly improve the thermal conductivity compared with the spherical point contact between the nano-spherical silver particles.
  • the addition amount of large-sized flake silver particles is a key factor for the obtained sintered silver layer to achieve efficient heat conduction and tight bonding.
  • the content of flaky silver particles is less than 2wt%, less flaky silver particles can not effectively improve the problem of excessive size shrinkage during sintering of nano-silver particles in the process of preparing the sintered silver layer. Due to the lack of sufficient heat conduction channels in the layer, the effect of enhancing thermal conductivity is not obvious; when the content of flake silver particles is greater than 20wt%, the flake silver particles basically do not participate in sintering during the sintering process, and there will be between them.
  • the thermal conductivity of the sintered silver layer 103 is 80-250W/(m ⁇ k), and the thickness is 2-30um.
  • the substrate 104 may be a metal substrate or a ceramic substrate with high thermal stability and thermal conductivity.
  • a copper substrate with high thermal conductivity, low price and good strength is preferred.
  • a layer of Au can be plated by evaporation or sputtering.
  • the protective layer protects the surface of the copper substrate from being oxidized and corroded, and the thickness of the Au layer protective layer is preferably 0.01um-0.1um.
  • copper metal as the substrate 104 has very good thermal conductivity, and ceramic substrates such as AlN or SiC are selected mainly because the thermal expansion coefficients of the luminescent ceramic layer and the ceramic substrate are close, which makes the wavelength conversion device more reliable. high. Although the thermal conductivity of ceramics is lower than that of copper substrates and the heat dissipation capacity is reduced, its high reliability can be applied to many high-precision light sources.
  • the wavelength conversion device 100 of this embodiment includes a luminescent ceramic layer 101 formed by stacking Al 2 O 3 encapsulated YAG:Ce phosphors in sequence, an Al 2 O 3 transition layer 101b, and a silver reflective film 102 , Ni anti-diffusion layer 102a, sintered silver layer 103, and gold-plated copper substrate 104.
  • the specific preparation method of the wavelength conversion device 100 is as follows:
  • Step 1 prepare a light-emitting layer, and polish the surface of the light-emitting layer
  • the powder After mixing Al 2 O 3 powder, YAG:Ce phosphor particles, MgO powder additive and Y 2 O 3 powder additive, drying and pulverizing to obtain powder, the powder is loaded into a graphite mold and sintered into a block in SPS , and then through annealing, cutting, grinding and polishing to obtain a luminescent ceramic layer 101 with a thickness of about 50um to 250um.
  • the ceramics processed to a certain thickness are polished on one side, and the polishing accuracy is within 15nm of roughness, and the surface looks and feels like a mirror surface.
  • Step 2 Coating of Luminescent Ceramic Layer
  • the luminescent ceramic layer 101 is placed in an electron beam evaporation machine, and reacted with O 2 after volatilization by the Al target, and an Al 2 O 3 transition layer 101b is deposited on the polished surface of the luminescent ceramic layer 101 with a thickness of about 10-200 nm.
  • the above samples are then taken out and put into a magnetron sputtering coater, and a layer of Ag reflective film 102 is firstly coated on the Al 2 O 3 transition layer 101b.
  • the film layer requires uniform crystallization and no abnormal stacking. It can provide good reflection performance; then also in the magnetron sputtering coating machine, replace the target head, and coat a layer of Ni anti-diffusion layer 102a on the Ag reflective film 102, the Ni layer does not need to be too thick, and its thickness is about 10nm ⁇ 500nm, It mainly plays the role of preventing the diffusion of Ag atoms.
  • the coated luminescent ceramic layer 101 is cut into a size of 5 ⁇ 5mm 2 for subsequent bonding.
  • the copper substrate 104 is processed into a substrate with an area of 20 ⁇ 20 mm 2 and a thickness of 3 mm, and several screw holes are left on the edge of the substrate to be fastened with other carrier screws. After the surface of the copper substrate 104 is polished, a layer of Au is plated with a thickness of about 0.01um-0.1um by means of evaporation or sputtering.
  • Step 4 Sintering combination of the coated luminescent ceramic layer and the copper substrate
  • a silver paste mixed with nano-spherical silver particles and large-sized flake silver particles is brushed on the copper substrate 104, the silver paste contains a small amount of organic solvent, and the content of the large-sized flake silver particles is 10 wt%.
  • the coated side of the luminescent ceramic layer 101 is covered on the silver paste, and then pressed and pressed with a jig, and then heated between 150°C and 300°C, preferably at 200°C-250°C; , the nano-spherical silver particles are melted, but the large-sized flake silver particles are not melted. After the nano-spherical silver particles are melted, the large flake silver particles are fused and connected together.
  • the formed sintered silver layer has low stress and good bonding performance, and at the same time, there are few internal holes.
  • the thermal conductivity of the sintered silver layer is 250W/(m ⁇ k), which has excellent thermal conductivity; the thickness of the sintered silver layer is about 2um to 30um, so that the luminescent ceramic layer 101 and the copper substrate 104 are closely connected together, as shown in the figure.
  • the wavelength conversion device 200 of this embodiment is similar to the wavelength conversion device 100 of the first embodiment, and includes an antireflection film 201a, a luminescent ceramic layer 201, an Al 2 O 3 transition layer 201b, a silver Reflective film 202 , Ni anti-diffusion layer 202 a , sintered silver layer 203 and AlN ceramic substrate 204 .
  • the specific preparation method of the wavelength conversion device 200 is as follows:
  • Step 1 prepare a light-emitting layer, and polish both sides of the light-emitting layer
  • the powder After mixing Al 2 O 3 powder, YAG:Ce phosphor particles, MgO powder additive and Y 2 O 3 powder additive, drying and pulverizing to obtain powder, the powder is loaded into a graphite mold and sintered into a block in SPS , and then through annealing, cutting, grinding and polishing to obtain a luminescent ceramic layer 201 with a thickness of about 50um to 250um.
  • the ceramics processed to a certain thickness are polished on both sides, and the polishing accuracy is within 15nm of roughness, and the surface looks and feels like a mirror.
  • Step 2 Coating of Luminescent Ceramic Layer
  • the luminescent ceramic layer 201 is placed in the electron beam evaporation machine, and the Al target is volatilized and reacted with O 2 , and a layer of Al 2 O 3 transition layer 201b is deposited on one polished surface of the luminescent ceramic layer 201 with a thickness of about 10-200nm. .
  • the above samples are then taken out and put into a magnetron sputtering coater, and a layer of Ag reflective film 202 is firstly coated on the Al 2 O 3 transition layer 201b.
  • the film layer requires uniform crystallization and no abnormal stacking. It can provide good reflection performance; then also in the magnetron sputtering coating machine, replace the target head, and coat a layer of Ni anti-diffusion layer 202a on the Ag reflective film 202, the Ni layer does not need to be too thick, and its thickness is about 10nm ⁇ 500nm, It mainly plays the role of preventing the diffusion of Ag atoms.
  • an anti-reflection AR film 201a is plated on another polished surface of the luminescent ceramic layer 201 (the upper surface of the luminescent ceramic layer 201 in this embodiment) with a thickness of about 0.01-0.1um to improve light extraction efficiency.
  • the coated luminescent ceramic layer 101 is cut into a size of 5 ⁇ 5mm 2 for subsequent bonding.
  • An AlN ceramic substrate with high thermal conductivity is selected, and its thermal conductivity is greater than 100 W/(m ⁇ k), and a SiC ceramic substrate can also be selected in other embodiments.
  • the AlN ceramic substrate is processed into a substrate with an area of 10 ⁇ 10 mm 2 and a thickness of 1 to 3 mm.
  • the present invention relates to the technical field of lighting and projection, and in particular, to a wavelength conversion device, a preparation method thereof, and a light-emitting device using the wavelength conversion device.
  • the continuous laser irradiation makes the working environment of the wavelength conversion device very harsh; in order to withstand the continuous irradiation of the laser light, a large amount of heat generated by the light-emitting layer during the wavelength conversion process cannot be eliminated.
  • the problem of thermal quenching caused by the rapid increase of its own temperature, the host material of the light-emitting layer has been developed from traditional organic materials to inorganic materials such as glass and ceramics with better thermal conductivity and heat resistance.
  • the connection between the light-emitting layer and the substrate generally adopts a solder layer or a sintered silver layer.
  • the sintered silver layer has better thermal conductivity than the solder layer, but there are some problems, such as:
  • the organic solvent in the middle area of the organic silver paste is difficult to volatilize, and the nano-spherical silver particles are easily sintered to cause excessive shrinkage in size.
  • the sintered silver layer has problems such as decreased cohesion and easy falling off due to large and large stress. At the same time, more pores are formed during the sintering process, which reduces the contact area between the nano-spherical silver particles and reduces the thermal conductivity.
  • the present invention provides a wavelength conversion device with high overall device reliability, good thermal conductivity and heat dissipation performance, and high luminous efficiency and a preparation method thereof.
  • the wavelength conversion device can be suitable for continuous high-power laser irradiation. .
  • the invention provides a wavelength conversion device, comprising a light-emitting layer, a reflective film, a sintered silver layer and a substrate stacked in sequence; the light-emitting layer converts the excitation light into outgoing light of different wavelengths, and the reflective film is coated on the On the light-emitting layer, it is used to reflect the light emitted from the light-emitting layer; the sintered silver layer connects the light-emitting layer and the substrate, and the sintered silver layer is connected to each other through surface contact. Flake silver particles.
  • the nano-spherical silver particles are melted and the flaky silver particles are combined to form a sintered silver layer.
  • the large-sized flake silver particles in the sintered silver layer improve the shrinkage of the sintered silver paste, reduce the sintering stress, and improve the adhesion performance of the sintered silver layer; at the same time, the large-sized flake silver particles in the sintered silver layer are mutually They are connected by surface contact, and the large-sized flake silver particles themselves serve as heat conduction channels and the surface contact heat transfer between each other greatly improves the thermal conductivity of the sintered silver layer.
  • the thermal conductivity of the sintered silver layer is 80-250 W/(m ⁇ k).
  • the content of flaky silver particles in the sintered silver layer is 2-20wt%, preferably 5-15wt%, more preferably 7-10wt%.
  • the light-emitting layer is a light-emitting ceramic layer, and the light-emitting layer made of ceramic material has the characteristics of excellent heat resistance and thermal conductivity.
  • the reflective film is a silver reflective film
  • the silver reflective film has the characteristics of compactness and high reflectivity.
  • a transition layer is arranged between the luminescent ceramic layer and the silver reflective film, the transition layer enhances the bonding force between the luminescent ceramic layer and the silver reflective film, and the transition layer can be an Al 2 O 3 layer or a SiO layer 2 layers; in addition, between the luminescent ceramic layer and the silver reflective film, alternating layers of high-refractive-index dielectric films and low-refractive-index dielectric films sequentially stacked on the silver reflective film can also be arranged, such as high-refractive index dielectric films.
  • the entire film layer can not only play the role of increasing reflection, but also serve as a transition layer between the silver reflective film and the luminescent ceramic layer to enhance the Ag film and the luminous Bonding of ceramic layers.
  • an anti-diffusion layer is arranged between the silver reflective film and the sintered silver layer, and the anti-diffusion layer can be a Ni layer, mainly to prevent the diffusion of Ag atoms in the silver reflective film and ensure that the silver reflective film has sufficient Reflectivity.
  • the substrate may be a substrate with bearing capacity and high thermal conductivity, such as a metal or ceramic substrate.
  • copper metal as a substrate has very good thermal conductivity
  • ceramic substrates such as AlN or SiC are selected mainly to reduce the stress caused by the difference in thermal expansion coefficient between the luminescent ceramic layer and the metal substrate during thermal expansion and contraction. , so that the reliability of the wavelength conversion device is higher.
  • the thermal conductivity of ceramics is lower than that of copper substrates and the heat dissipation capacity is reduced, its high reliability can be applied to many high-precision light sources.
  • the present invention also provides a light-emitting device, comprising an excitation light source and the above-mentioned wavelength conversion device, and the light-emitting device is suitable for the fields of illumination and projection.
  • the present invention also provides a method for preparing a wavelength conversion device, comprising the following steps:
  • Step 1 preparing a light-emitting layer, and polishing the surface of the light-emitting layer
  • Step 2 forming a reflective film on the polished surface of the light-emitting layer through a physical sputtering or evaporation process
  • Step 3 apply the silver paste mixed with nano-spherical silver particles and flake silver particles on one surface of the substrate;
  • Step 4 superimpose the surface of the light-emitting layer coated with the reflective film on the surface of the substrate coated with the silver paste;
  • Step 5 Sinter the entire device.
  • the content of flake silver particles in the silver paste in step 3 is 2-20wt%, preferably 5-15wt%, more preferably 7-10wt%.
  • the light-emitting layer prepared in step 1 is a light-emitting ceramic layer.
  • the reflective film formed on the polished surface of the luminescent ceramic layer by a physical sputtering or evaporation process is a silver reflective film.
  • it also includes forming a transition layer on the polished surface of the luminescent ceramic layer by physical sputtering or evaporation, and the transition layer can be an Al 2 O 3 layer or a SiO 2 layer; further
  • it also includes alternating layers of a low-refractive-index dielectric film and a high-refractive-index dielectric film formed by physical sputtering or evaporation, which are sequentially laminated on the polished surface of the luminescent ceramic layer, such as a high-refractive-index dielectric film.
  • step 2 it also includes forming an anti-diffusion layer on the silver reflective film by physical sputtering or evaporation, and the anti-diffusion layer may be a metal Ni layer.
  • the substrate in step 3 is a metal substrate or a ceramic substrate
  • the metal substrate may be a copper metal substrate
  • the ceramic substrate may be an AlN or SiC substrate.
  • the present invention includes the following beneficial effects:
  • a sintered silver layer with extremely high thermal conductivity is used between the light-emitting layer and the heat dissipation substrate to connect and conduct. It is formed by the mixing and sintering of silver particles, and the melting of nano-spherical silver particles to combine large-sized flake silver particles.
  • the large-sized flake silver particles in the prepared sintered silver layer improve the shrinkage of the sintered silver paste, reduce the sintering stress, and improve the adhesion performance of the sintered silver layer; at the same time, the large-sized flake silver particles in the sintered silver layer are mutually They are in surface contact, and the large-sized silver particles themselves serve as heat conduction channels and the surface contact heat transfer between them can improve the thermal conductivity of the sintered silver layer.
  • FIG. 1 is a schematic structural diagram of a wavelength conversion device according to Embodiment 1 of the present invention.
  • FIG. 2 is a schematic structural diagram of a wavelength conversion device according to Embodiment 2 of the present invention.
  • FIG. 3 is a schematic structural diagram of a wavelength conversion device according to Embodiment 3 of the present invention.
  • FIG. 4 is a schematic structural diagram of the sintered silver layer of the present invention.
  • the current sintered silver is mainly used in small-sized packages in device packaging, and relatively few applications in areas larger than 4*4mm 2 .
  • the organic solvent in the middle area of sintered silver it is difficult for the organic solvent in the middle area of sintered silver to volatilize during the sintering process, and the nano-silver particles are likely to cause excessive shrinkage and large stress during sintering, which affects the packaging performance (such as decreased adhesion);
  • more pores are formed in the sintered silver layer, which reduces the contact area between the silver nanoparticles and reduces the thermal conductivity.
  • a sintered silver layer with excellent performance is prepared by mixing and sintering nano-silver particles and large-size flake silver particles, and the sintered silver layer is applied as a heat-conducting bonding layer between a light-emitting layer and a substrate in a wavelength conversion device, thereby obtaining device reliability. High and good thermal conductivity wavelength conversion device.
  • the present invention provides a wavelength conversion device 100 , which includes a light-emitting layer 101 , a reflective film 102 , a sintered silver layer 103 and a substrate 104 that are stacked in sequence.
  • the light-emitting layer 101 converts the excitation light into outgoing light of different wavelengths
  • the reflective film 102 is coated on the light-emitting layer 101 to reflect the outgoing light from the light-emitting layer 101 ;
  • the sintered silver layer 103 connects the light-emitting layer 101 and the substrate 104 , the sintered silver layer 103 contains flake silver particles connected with each other through surface contact.
  • the light-emitting layer 101 is usually a light-emitting ceramic layer with good heat dissipation and heat resistance.
  • the light-emitting material that is, the wavelength conversion material
  • its composition is not particularly limited.
  • it can be aluminate phosphor, halophosphoric acid phosphor One of the phosphors, garnet-based phosphors or quantum dots.
  • the luminescent ceramic layer 101 may be a YAG pure-phase luminescent ceramic, or a complex-phase luminescent ceramic prepared by mixing YAG with Al 2 O 3 powder or AlN powder.
  • Al 2 O 3 can be used to encapsulate YAG:Ce phosphor powder to form a luminescent ceramic layer.
  • the thickness of the luminescent ceramic layer is about 50-250um when comprehensively considering luminous efficiency and thermal conductivity.
  • an anti-reflection film 101a may be disposed on the upper surface of the light-emitting layer 101 facing the incident light.
  • the anti-reflection film 101a can play the role of anti-reflection and anti-reflection, that is, reducing the reflectivity of the incident excitation light on the upper surface of the light-emitting layer 101 and increasing the transmittance of the excitation light on the light-emitting layer 101, which is beneficial to improve the light output on the surface of the light-emitting layer 101 effectiveness.
  • the thickness of the anti-reflection film 101a is preferably 0.01um ⁇ 0.1um.
  • the reflective film 102 coated on the light-emitting layer 101 may be a silver reflective film, which is generally coated on one surface of the light-emitting layer 101 by techniques such as physical sputtering or evaporation, and the obtained silver reflective film It has the characteristics of compactness and high reflectivity, and the thickness of the silver reflective film is preferably 10nm to 1um.
  • a transition layer 101b can be first plated on the luminescent ceramic layer, and then the silver reflective film is plated.
  • 101b can be an Al 2 O 3 layer or a SiO 2 layer; in addition, an alternating film of a low-refractive-index dielectric film and a high-refractive-index dielectric film that are sequentially stacked on the luminescent ceramic layer can also be arranged between the luminescent ceramic layer and the silver reflective film.
  • the entire film layer can not only play the role of increasing reflection, but also serve as a transition layer between the silver reflective film and the luminescent ceramic layer, enhancing the Combination of Ag film and luminescent ceramic layer.
  • the thickness of the transition layer 101b is about 10-200 nm.
  • a layer of anti-diffusion layer 102a can be plated on the silver reflective film and then connected to the sintered silver layer 103; the anti-diffusion layer 102a It can be a metal Ni layer with a thickness of about 10-500nm.
  • the sintered silver layer 103 of the present application is prepared by sintering nano-spherical silver particles and large-sized flake silver particles.
  • the radius of curvature of the nano-spherical silver particles is relatively consistent in all directions, and it is easy to melt and flow during the sintering process; while the large-sized flake silver particles are generally cuboid or flat, and their length in the longitudinal or flat direction is much larger than that in the sintering process.
  • the length in the thickness direction is not easy to melt during the sintering process, which prevents the material from shrinking excessively; in this way, during the sintering process, the large-sized flake silver particles support each other, and are melted and bonded by nano-spherical silver particles, and finally form a card containing a card
  • the sintered silver layer 103 of the large-sized flake silver particles in the bridge structure and in surface contact with each other has a larger contact area between the flake silver particles, which better forms a thermal conduction network.
  • the sintered silver layer 103 may be a structure in which flaky silver stacked between layers is bonded by molten silver, as shown in FIG. 4 , where 1 represents large-sized flaky silver particles, and 2 represents the melting point between them. Silver for connection.
  • the raw silver paste for sintering the silver layer is an organic silver paste mixed with nano-spherical silver particles and large-sized flake silver particles, which contains a small amount of organic solvent, and the content of flake silver particles is 2-20wt%, preferably 5-15 wt %, more preferably 7-10 wt %, the size of the flake silver particles is above the micron level.
  • the sintering activity is very small compared to the nano-spherical silver particles.
  • the nano-spherical silver particles are sintered and melted to bond and connect the flaky silver particles, and the content of the flaky silver particles in the formed sintered silver layer is almost unchanged.
  • the introduction of large-sized flake silver particles can well solve the problems of excessive size shrinkage and large stress of nano-spherical silver particles during the sintering process, and improve the bonding performance of the sintered silver layer;
  • the flaky silver particles are in surface contact, which can greatly improve the thermal conductivity compared with the spherical point contact between the nano-spherical silver particles.
  • the addition amount of the large-sized flake silver particles is a key factor for the obtained sintered silver layer to achieve efficient heat conduction and tight bonding.
  • the content of flaky silver particles is less than 2 wt%, less flaky silver particles can not effectively improve the problem of excessive size shrinkage during sintering of nano-silver particles during the preparation of the sintered silver layer. Due to the lack of sufficient heat conduction channels in the layer, the effect of enhancing thermal conductivity is not obvious; when the content of flake silver particles is greater than 20wt%, the flake silver particles basically do not participate in sintering during the sintering process, and there will be between them.
  • the thermal conductivity of the sintered silver layer 103 is 80-250 W/(m ⁇ k), and the thickness is 2-30 ⁇ m.
  • the substrate 104 may be a metal substrate or a ceramic substrate with high thermal stability and thermal conductivity.
  • a copper substrate with high thermal conductivity, low price and good strength is preferred.
  • a layer of Au can be plated by evaporation or sputtering.
  • the protective layer protects the surface of the copper substrate from being oxidized and corroded, and the thickness of the Au layer protective layer is preferably 0.01um-0.1um.
  • copper metal as the substrate 104 has very good thermal conductivity, and ceramic substrates such as AlN or SiC are selected mainly because the thermal expansion coefficients of the luminescent ceramic layer and the ceramic substrate are close, which makes the wavelength conversion device more reliable. high. Although the thermal conductivity of ceramics is lower than that of copper substrates and the heat dissipation capacity is reduced, its high reliability can be applied to many high-precision light sources.
  • the wavelength conversion device 100 of this embodiment includes a luminescent ceramic layer 101 formed by stacking Al 2 O 3 encapsulated YAG:Ce phosphors in sequence, an Al 2 O 3 transition layer 101b, and a silver reflective film 102 , Ni anti-diffusion layer 102a, sintered silver layer 103, and gold-plated copper substrate 104.
  • the specific preparation method of the wavelength conversion device 100 is as follows:
  • Step 1 prepare a light-emitting layer, and polish the surface of the light-emitting layer
  • the powder After mixing Al 2 O 3 powder, YAG:Ce phosphor particles, MgO powder additive and Y 2 O 3 powder additive, drying and pulverizing to obtain powder, the powder is loaded into a graphite mold and sintered into a block in SPS , and then through annealing, cutting, grinding and polishing to obtain a luminescent ceramic layer 101 with a thickness of about 50um to 250um.
  • the ceramics processed to a certain thickness are polished on one side, and the polishing accuracy is within 15nm of roughness, and the surface looks and feels like a mirror surface.
  • Step 2 Coating of Luminescent Ceramic Layer
  • the luminescent ceramic layer 101 is placed in an electron beam evaporation machine, and reacted with O 2 after volatilization by the Al target, and an Al 2 O 3 transition layer 101b is deposited on the polished surface of the luminescent ceramic layer 101 with a thickness of about 10-200 nm.
  • the above samples are then taken out and put into a magnetron sputtering coater, and a layer of Ag reflective film 102 is firstly coated on the Al 2 O 3 transition layer 101b.
  • the film layer requires uniform crystallization and no abnormal stacking. It can provide good reflection performance; then also in the magnetron sputtering coating machine, replace the target head, and coat a layer of Ni anti-diffusion layer 102a on the Ag reflective film 102, the Ni layer does not need to be too thick, and its thickness is about 10nm ⁇ 500nm, It mainly plays the role of preventing the diffusion of Ag atoms.
  • the coated luminescent ceramic layer 101 is cut into a size of 5 ⁇ 5mm 2 for subsequent bonding.
  • the copper substrate 104 is processed into a substrate with an area of 20 ⁇ 20 mm 2 and a thickness of 3 mm. Several screw holes are left on the edge of the substrate to be fastened with other carrier screws. After the surface of the copper substrate 104 is polished, a layer of Au is plated with a thickness of about 0.01um-0.1um by means of evaporation or sputtering.
  • Step 4 Sintering combination of the coated luminescent ceramic layer and the copper substrate
  • a silver paste mixed with nano-spherical silver particles and large-sized flake silver particles is brushed on the copper substrate 104, the silver paste contains a small amount of organic solvent, and the content of the large-sized flake silver particles is 10 wt%.
  • the coated side of the luminescent ceramic layer 101 is covered on the silver paste, and then pressed and pressed with a jig, and then heated between 150°C and 300°C, preferably at 200°C-250°C; , the nano-spherical silver particles are melted, but the large-sized flake silver particles are not melted. After the nano-spherical silver particles are melted, the large flake silver particles are fused and connected together.
  • the formed sintered silver layer has low stress and good bonding performance, and at the same time, there are few internal holes.
  • the thermal conductivity of the sintered silver layer is 250W/(m ⁇ k), which has excellent thermal conductivity; the thickness of the sintered silver layer is about 2um to 30um, so that the luminescent ceramic layer 101 and the copper substrate 104 are closely connected together, as shown in the figure.
  • the wavelength conversion device 200 of this embodiment is similar to the wavelength conversion device 100 of the first embodiment, and includes an antireflection film 201a, a luminescent ceramic layer 201, an Al 2 O 3 transition layer 201b, a silver Reflective film 202 , Ni anti-diffusion layer 202 a , sintered silver layer 203 and AlN ceramic substrate 204 .
  • the specific preparation method of the wavelength conversion device 200 is as follows:
  • Step 1 prepare a light-emitting layer, and polish both sides of the light-emitting layer
  • the powder After mixing Al 2 O 3 powder, YAG:Ce phosphor particles, MgO powder additive and Y 2 O 3 powder additive, drying and pulverizing to obtain powder, the powder is loaded into a graphite mold and sintered into a block in SPS , and then through annealing, cutting, grinding and polishing to obtain a luminescent ceramic layer 201 with a thickness of about 50um to 250um.
  • the ceramics processed to a certain thickness are polished on both sides, and the polishing accuracy is within 15nm of roughness, and the surface looks and feels like a mirror.
  • Step 2 Coating of Luminescent Ceramic Layer
  • the luminescent ceramic layer 201 is placed in the electron beam evaporation machine, and the Al target is volatilized and reacted with O 2 , and a layer of Al 2 O 3 transition layer 201b is deposited on one polished surface of the luminescent ceramic layer 201 with a thickness of about 10-200nm. .
  • the above samples are then taken out and put into a magnetron sputtering coater, and a layer of Ag reflective film 202 is firstly coated on the Al 2 O 3 transition layer 201b.
  • the film layer requires uniform crystallization and no abnormal stacking. It can provide good reflection performance; then also in the magnetron sputtering coating machine, replace the target head, and coat a layer of Ni anti-diffusion layer 202a on the Ag reflective film 202, the Ni layer does not need to be too thick, and its thickness is about 10nm ⁇ 500nm, It mainly plays the role of preventing the diffusion of Ag atoms.
  • an anti-reflection AR film 201a is plated on another polished surface of the luminescent ceramic layer 201 (the upper surface of the luminescent ceramic layer 201 in this embodiment) with a thickness of about 0.01-0.1um to improve light extraction efficiency.
  • the coated luminescent ceramic layer 101 is cut into a size of 5 ⁇ 5mm 2 for subsequent bonding.
  • An AlN ceramic substrate with high thermal conductivity is selected, and its thermal conductivity is greater than 100 W/(m ⁇ k), and a SiC ceramic substrate can also be selected in other embodiments.
  • the AlN ceramic substrate is processed into a substrate with an area of 10x10mm 2 and a thickness of 1-3mm. After the surface is polished and polished, a copper layer is made on the surface by a copper cladding process, and then a layer of copper is plated by evaporation or sputtering. Layer Au layer, Au thickness of about 0.01 ⁇ 0.1um.
  • Step 4 Sintering and bonding of the coated luminescent ceramic layer and the ceramic substrate
  • a silver paste mixed with nano-spherical silver particles and large-sized flake silver particles is brushed on the AlN ceramic substrate 204, the silver paste contains a small amount of organic solvent, and the content of the large-sized flake silver particles is 2-20wt%.
  • the side of the luminescent ceramic layer 201 plated with the silver reflective film 102 is covered on the silver paste, and then pressed and pressed with a jig, and then heated between 150°C and 300°C, preferably between 200°C and 200°C. 250 ° C; at this time, the nano-spherical silver particles are melted, but the large-sized flake silver particles are not melted.
  • the formed sintered silver layer 203 has low stress and good bonding performance, and at the same time, there are few internal holes, and the large particles of flaky silver are in contact with each other to form a more effective heat conduction channel, and the heat conduction performance is good.
  • the thermal conductivity of the sintered silver layer 203 is 80-250W/(m ⁇ k), which has excellent thermal conductivity; the thickness of the sintered silver layer 203 is about 2um to 30um, so that the luminescent ceramic layer 201 and the AlN ceramic substrate 204 are closely connected on the Together, a wavelength conversion device 200 as shown in FIG. 2 is obtained.
  • the second embodiment uses an AlN ceramic substrate to replace the copper substrate.
  • the thermal conductivity of the AlN ceramic substrate is lower than that of the copper substrate and the heat dissipation capacity is reduced, the thermal expansion coefficient of the AlN ceramic substrate is closer to that of the luminescent ceramic layer.
  • the wavelength conversion device 200 has higher reliability and can be applied to many high-precision light sources.
  • the wavelength conversion device 300 in this embodiment is similar to the wavelength conversion device 100 in the first embodiment, and includes an antireflection film 301a, a luminescent ceramic layer 301, a high and low refractive index alternately coated dielectric layer 301b, Silver reflective film 302, Ni anti-diffusion layer 302a, sintered silver layer 303, and gold-plated copper substrate 304.
  • the specific preparation method of the wavelength conversion device 300 is as follows:
  • Step 1 prepare a light-emitting layer, and polish both sides of the light-emitting layer
  • the powder After mixing Al 2 O 3 powder, YAG:Ce phosphor particles, MgO powder additive and Y 2 O 3 powder additive, drying and pulverizing to obtain powder, the powder is loaded into a graphite mold and sintered into a block in SPS , and then through annealing, cutting, grinding and polishing to obtain a luminescent ceramic layer 301 with a thickness of about 50um to 250um.
  • the ceramics processed to a certain thickness are polished on both sides, the polishing accuracy is within 15nm of roughness, and the surface appearance is mirror surface.
  • Step 2 Coating of Luminescent Ceramic Layer
  • the alternate film layers are the low-refractive-index dielectric film 301b2 and the high-refractive-index dielectric film 301b1, and the low-refractive-index dielectric film and high-refractive index dielectric films are TiO 2 and SiO 2 respectively.
  • This alternating dielectric film can be 2 layers or dozens of layers. In the third embodiment, it is 2 layers, and the overall thickness is about 10nm-200nm.
  • the alternating refractive index coating dielectric layer 301b can not only play the role of increasing reflection, but also enhance the combination of the silver reflective film 302 and the luminescent ceramic layer 301 .
  • the above samples are then taken out and put into a magnetron sputtering coating machine, and a layer of Ag reflective film 302 is firstly coated on the high and low refractive index alternating coating medium layer 301b.
  • the film layer requires uniform crystallization and no abnormal stacking. , can provide good reflection performance; then also in the magnetron sputtering coating machine, replace the target head, and coat a layer of Ni anti-diffusion layer 302a on the Ag reflective film 302, the Ni layer does not need to be too thick, and its thickness is about 10nm ⁇ 500nm , mainly to prevent the diffusion of Ag atoms.
  • an anti-reflection AR film 301a is plated on another polished surface of the luminescent ceramic layer 301 (the upper surface of the luminescent ceramic layer 301 in this embodiment) with a thickness of about 0.01-0.1um to improve the light extraction efficiency.
  • the coated luminescent ceramic layer 301 is cut into a size of 5x5mm 2 for subsequent bonding.
  • the copper substrate 304 is processed into a substrate with an area of 20 ⁇ 20 mm 2 and a thickness of 3 mm. Several screw holes are left on the edge of the substrate to be fastened with other carrier screws. After the surface of the copper substrate 304 is polished, a layer of Au is plated with a thickness of about 0.01um-0.5um by means of evaporation or sputtering.
  • Step 4 Combination of Luminescent Ceramic Layer and Copper Substrate
  • a silver paste mixed with nano-spherical silver particles and large-sized flake silver particles is brushed on the copper substrate 304, the silver paste contains a small amount of organic solvent, and the content of the large-sized flake silver particles is 2-20 wt%.
  • the silver paste contains a small amount of organic solvent, and the content of the large-sized flake silver particles is 2-20 wt%.
  • one side of the luminescent ceramic layer 301 with the silver-plated reflective film 302 is covered on the silver paste, and then pressed and pressed with a jig, and then heated between 150°C and 300°C, preferably between 200°C and 250°C. °C; at this time, the nano-spherical silver particles are melted, but the large-sized flake silver particles are not melted.
  • the formed sintered silver layer 303 has low stress and good bonding performance, and at the same time, there are few internal holes.
  • the thermal conductivity of the sintered silver layer 303 is 80-250W/(m ⁇ k) and has excellent thermal conductivity; the thickness of the sintered silver layer 303 is about 2um to 30um, so that the luminescent ceramic layer 301 and the copper substrate 304 are closely connected together , the wavelength conversion device 300 shown in FIG. 3 is obtained.
  • This example is the same as Example 1 except that the content of large-sized flake silver particles in the sintered silver layer paste is 7wt% in step 4, and the thermal conductivity of the obtained sintered silver layer is 220W/(m ⁇ k).
  • This example is the same as Example 1, except that the content of large-sized flake silver particles in the sintered silver layer paste in step 4 is 15wt% ⁇ k).
  • This example is the same as Example 1 except that the content of large-sized flake silver particles in the sintered silver layer paste is 5wt% in step 4, and the thermal conductivity of the obtained sintered silver layer is 150W/(m ⁇ k).
  • Example 2 This example is the same as Example 1, except that the content of large-sized flake silver particles in the sintered silver layer paste in step 4 is 1wt%, the rest of the steps are the same as in Example 1.
  • the thermal conductivity of the layer is less than 80 W/(m ⁇ k).
  • step 4 when the content of large-sized flake silver particles in the sintered silver layer paste is selected to be 22 wt%, there are voids between the large-sized flake silver particles during the sintering process, and the overall density is poor.
  • the sintered silver layer cannot effectively bond the light-emitting layer and the substrate.
  • Embodiments of the present invention further provide a light-emitting device, the light-emitting device includes an excitation light source and a wavelength conversion device, wherein the wavelength conversion device may have the structures and functions in the foregoing embodiments.
  • the light-emitting device can be applied to a projection system, such as a liquid crystal display (LCD, Liquid Crystal Display) or a digital light path processor (DLP, Digital Light Processor) projector; it can also be applied to a lighting system, such as a car lighting or stage lights; It can be applied in the field of 3D display technology.
  • a projection system such as a liquid crystal display (LCD, Liquid Crystal Display) or a digital light path processor (DLP, Digital Light Processor) projector
  • DLP Digital Light Processor

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Abstract

本发明涉及一种波长转换装置及其制备方法。该波长转换装置包括依次叠置的发光层、反射膜、烧结银层和基板，所述发光层将激发光转换成不同波长的出射光，所述反射膜镀覆在所述发光层上、用于反射从所述发光层出射的所述出射光；所述烧结银层连接所述发光层和所述基板，所述烧结银层中包含相互之间通过面接触连接的片状银颗粒，该烧结银层通过混合有纳米球形银颗粒和片状银颗粒的银浆烧结而成。该波长转换装置具有整体装置导热性能好、发光效率高等特点。

Description

波长转换装置及其制备方法 技术领域
本发明涉及照明和投影技术领域，特别是涉及一种波长转换装置及其制备方法，以及采用该波长转换装置的发光装置。
背景技术
随着显示和照明技术的发展，原始的LED或卤素灯泡作为光源越来越不能满足显示和照明高功率和高亮度的需求。采用固态光源如LD(Laser Diode，激光二极管)发出的激发光以激发波长转换材料的方法能够获得各种颜色的可见光，该技术越来越多的应用于照明和显示中。这种技术具有效率高、能耗少、成本低、寿命长的优势，是现有白光或者单色光光源的理想替代方案。
现有技术中波长转换装置在采用激光光源照射激发时，激光连续照射使波长转换装置的工作环境十分苛刻；为了经受住激光的连续照射，防止出现波长转换过程中发光层产生的大量热量无法排除、使自身温度快速提高而导致热淬灭的问题，发光层的主体材料已经从传统的有机材料发展到导热、耐热更好的玻璃、陶瓷等无机材料。
对于波长转换装置整体的导热性能和发光效率来说，发光层到基板的热传导通道是否通畅也是一个关键因素。目前发光层和基板之间的连接一般采用焊接层或烧结银层，其中烧结银层相比于焊接层的导热能力更好，但是也存在一些问题，例如：
在有机银浆烧结形成烧结银层的过程中，特别是在4*4mm 2以上的大尺寸封装上，有机银浆中间区域的有机溶剂挥发困难，纳米球形银颗粒在烧结时容易造成收缩尺寸过大、应力较大，造成烧结银层粘结性下降、容易脱落等问题；同时烧结过程中形成了较多的孔隙，使得纳米球形银颗粒间接触面积减少，降低了导热性能。
因而需要开发一种整体可靠性好、导热散热性能优异的波长转换装 置。
发明内容
针对上述现有技术存在的缺陷，本发明提供了一种整体装置可靠性高、导热散热性能好、发光效率高的波长转换装置及其制备方法，该波长转换装置能够适用于大功率激光连续照射。
本发明提供了一种波长转换装置，包括依次叠置的发光层、反射膜、烧结银层和基板；所述发光层将激发光转换成不同波长的出射光，所述反射膜镀覆在所述发光层上、用于反射从所述发光层出射的所述出射光；所述烧结银层连接所述发光层和所述基板，所述烧结银层中包含相互之间通过面接触连接的片状银颗粒。
本发明的技术方案中，通过将纳米球形银颗粒和片状银颗粒混合烧结，纳米球形银颗粒融化而将片状银颗结合起来形成烧结银层。在烧结银层中大尺寸片状银颗粒改善了烧结银浆的收缩、减少了烧结应力，提高了烧结银层的粘接性能；同时，烧结银层中的大尺寸片状银颗粒相互之间是面接触连接的，大尺寸片状银颗粒本身作为导热通道以及相互之间的面接触传热作用很好的提高了烧结银层的导热性能。
优选的，所述烧结银层的热导率为80-250W/(m·k)。
优选的，所述烧结银层中片状银颗粒的含量为2-20wt％，优选5-15wt％，更优选7-10wt％。
优选的，所述发光层为发光陶瓷层，陶瓷材料制成的发光层具有耐热、导热性能优异的特点。
优选的，所述反射膜为银反射膜，银反射膜具有致密、高反射率的特点。
优选的，在所述发光陶瓷层和所述银反射膜之间设置一过渡层，过渡层增强了发光陶瓷层和银反射膜之间的结合力，过渡层可以为Al 2O 3层或SiO 2层；另外，在所述发光陶瓷层和所述银反射膜之间也可以设置依次层叠在所述银反射膜上的高折射率介质膜和低折射率介质膜的交替膜层，例如高折射率的SiO 2介质膜和低折射率的TiO 2介质膜，整个膜层既可以起到增加反射的作用，也可以作为银反射膜与发光陶瓷层之 间的过渡层，增强Ag膜与发光陶瓷层的结合。
优选的，在所述银反射膜与所述烧结银层之间设置一防止扩散层，防止扩散层可以为Ni层，主要是防止银反射膜中Ag原子的扩散，保证银反射膜具有足够的反射率。
优选的，所述基板可以选择具有承载能力、导热率高的基板，例如金属或陶瓷基板。
在一些实施例中，铜金属作为基板具有非常好的热导率，而选择AlN或SiC等陶瓷基板主要是为了减轻热胀冷缩时因发光陶瓷层与金属基板的热膨胀系数差异带来的应力，使波长转换装置的可靠性更高。虽然陶瓷作基板时热导率低于铜基板、散热能力有所下降，但是其高可靠性可以应用于很多高精密的光源。
本发明还提供了一种发光装置，包括激发光源及上述波长转换装置，该发光装置适用于照明和投影领域。
另一方面，本发明还提供了一种波长转换装置的制备方法，其包括以下步骤：
步骤1：制备发光层，并对所述发光层的表面进行抛光；
步骤2：通过物理溅射或蒸镀工艺在所述发光层抛光的表面上形成反射膜；
步骤3：将混合有纳米球形银颗粒和片状银颗粒的银浆涂敷在基板的一个表面上；
步骤4：将所述发光层镀覆有反射膜的一面叠置在所述基板的涂敷有所述银浆的表面上；
步骤5：对整个装置进行烧结。
优选的，步骤3中所述银浆中片状银颗粒的含量为2-20wt％，优选5-15wt％，更优选7-10wt％。
优选的，步骤1中制备的发光层为发光陶瓷层。
优选的，步骤2中，通过物理溅射或蒸镀工艺在所述发光陶瓷层抛光的表面上形成的反射膜为银反射膜。更进一步的，在步骤2之前，还包括在所述发光陶瓷层抛光的表面上通过物理溅射或蒸镀形成一层过渡层，过渡层可以为Al 2O 3层或SiO 2层；更进一步的，在步骤2之前， 还包括通过物理溅射或蒸镀形成的依次层叠在所述发光陶瓷层抛光的表面上的低折射率介质膜和高折射率介质膜的交替膜层，例如高折射率的SiO 2介质膜和低折射率的TiO 2介质膜。更进一步的，在步骤2之后，还包括在所述银反射膜上通过物理溅射或蒸镀形成一层防止扩散层，防止扩散层可以是金属Ni层。
优选的，步骤3中所述基板选择金属基板或陶瓷基板，金属基板可以为铜金属基板，陶瓷基板可以为AlN或SiC基板。
与现有技术相比，本发明包括如下有益效果：
本发明的波长转换装置为了获得高效的导热散热能力，其发光层和散热基板之间采用热导率极高的烧结银层连接导通，烧结银层是通过将纳米球形银颗粒和大尺寸片状银颗粒混合烧结、纳米球形银颗粒融化而将大尺寸片状银颗结合起来而形成的。制得的烧结银层中大尺寸片状银颗粒改善了烧结银浆的收缩、减少了烧结应力，提高了烧结银层的粘接性能；同时，烧结银层中的大尺寸片状银颗粒相互之间是面接触的，大尺寸银颗粒本身作为导热通道以及相互之间的面接触传热作用很好的提高了烧结银层的导热性能。
附图说明
附图仅用于示出具体实施例的目的，而并不认为是对本发明的限制。
图1为本发明实施例一的波长转换装置的结构示意图。
图2为本发明实施例二的波长转换装置的结构示意图。
图3为本发明实施例三的波长转换装置的结构示意图。
图4为本发明的烧结银层的结构示意图。
具体实施方式
下面结合附图和实施方式对本发明实施例进行详细说明。
正如背景技术所述，目前的烧结银在器件封装方面主要是应用在小尺寸封装上，在4*4mm 2以上尺寸面积上的应用还是相对较少。在大尺寸封装上，烧结银在烧结过程中中间区域的有机溶剂挥发较困难，且纳米银颗粒在烧结时容易造成收缩尺寸过大、应力较大，影响封装性能(如 粘接性下降)；同时，烧结银层中形成了较多的孔隙，使得纳米银颗粒间接触面积减少，降低了导热性能。
本发明通过混合烧结纳米银颗粒和大尺寸片状银颗粒，制得性能优异的烧结银层，将其应用为波长转换装置中发光层和基板之间的导热粘接层，获得了装置可靠性高、导热效果好的波长转换装置。
请参考图1，本发明提供了一种波长转换装置100，其包括依次叠置的发光层101、反射膜102、烧结银层103和基板104。其中，发光层101将激发光转换成不同波长的出射光，反射膜102镀覆在发光层101上、用于反射从发光层101出射的出射光；烧结银层103连接发光层101和基板104，烧结银层103中包含相互之间通过面接触连接的片状银颗粒。
在本申请中，发光层101通常是具有良好散热、耐热性能的发光陶瓷层，作为其中的发光材料即波长转换材料，其成分没有特别限定，例如可以为铝酸盐荧光粉、卤磷酸荧光粉、石榴石系荧光粉或量子点中的一种。特别的，当波长转换材料选择YAG石榴石系荧光粉时，发光陶瓷层101可以为YAG纯相发光陶瓷，也可以为YAG与Al 2O 3粉或AlN粉混合烧制的复相发光陶瓷。在一具体实施例中可以采用Al 2O 3封装YAG：Ce荧光粉形成发光陶瓷层，优选的，在综合考虑发光效率和导热率的情况下，发光陶瓷层的厚度约为50-250um。
进一步的，在发光层101面向入射光的上表面还可以设置一增透膜101a。增透膜101a可起到增透减反的作用，即减少入射激发光在发光层101上表面的反射率，增加激发光在发光层101的透过率，有利于提升发光层101表面的出光效率。在一具体实施例中，增透膜101a优选厚度为0.01um～0.1um。
在本申请中，镀覆于发光层101上的反射膜102可以为银反射膜，其一般采用物理溅射或蒸镀等技术镀覆于发光层101的一个表面上，制得的银反射膜具有致密、高反射率的特点，优选银反射膜的厚度为10nm～1um。
进一步的，对于发光陶瓷层和银反射膜来说，为了增强两者之间的结合力，可以先在发光陶瓷层上先镀上一层过渡层101b后再镀银反射 膜，这里的过渡层101b可以为Al 2O 3层或SiO 2层；另外，也可以在发光陶瓷层和银反射膜之间设置依次层叠在发光陶瓷层上的低折射率介质膜和高折射率介质膜的交替膜层，例如高折射率的SiO 2介质膜和低折射率的TiO 2介质膜，整个膜层既可以起到增加反射的作用，也可以作为银反射膜与发光陶瓷层之间的过渡层，增强Ag膜与发光陶瓷层的结合。过渡层101b的厚度约为10-200nm。
另外，为了防止银反射膜中Ag原子的扩散，保证银反射膜具有足够的反射率，可以在银反射膜上镀上一层防止扩散层102a后再与烧结银层103连接；防止扩散层102a可以为金属Ni层，厚度约为10-500nm。
对于本申请的烧结银层103来说，其是由纳米球形银颗粒和大尺寸片状银颗粒烧结制得。纳米球形的银颗粒在各个方向的曲率半径较为一致，易于在烧结过程中融化流动；而大尺寸片状银颗粒一般为长方体状或扁平状，其在长度方向或扁平方向的长度远大于其在厚度方向的长度，在烧结过程中不易融化，阻碍材料过度收缩；这样，在烧结过程中，大尺寸片状银颗粒之间相互支撑，其间由纳米球形银颗粒熔融粘接，最终形成为包含卡片搭桥结构的、相互之间面接触的大尺寸片状银颗粒的烧结银层103，其各片状银颗粒间的接触面积较大，更好地形成导热网络。例如，烧结银层103可以为层间堆叠的片状银之间由融化的银粘接的结构，如图4所示，其中1表示大尺寸片状银颗粒，2表示它们之间融化的起连接作用的银。
对于烧结银层的原料银浆来说，其是混合有纳米球形银颗粒和大尺寸片状银颗粒的有机银浆，其中含有少量有机溶剂，片状银颗粒的含量为2-20wt％，优选5-15wt％，更优选7-10wt％，片状银颗粒的尺寸为微米级以上。在烧结过程中，由于片状银颗粒的尺寸较大，相比于纳米球形银颗粒烧结活性很小，在150℃-300℃(优选在200℃-250℃)温度烧结时，其难以参与烧结，几乎能维持其形状，纳米球形银颗粒烧结融化将片状银颗粒结合连接，形成的烧结银层中片状银颗粒的含量几乎不变。大尺寸片状银颗粒的引入相对于只有纳米球形银颗粒来说，可以很好地解决烧结过程中纳米球形银颗粒尺寸收缩过大、应力较大的问题，改善烧结银层的粘结性能；同时片状银颗粒间是面接触，相比于纳米球形银 颗粒间的球形点接触，可以很好的提高其导热性能。
如上所述，在烧结银层的原料银浆中，其大尺寸片状银颗粒的添加量是制得的烧结银层实现高效导热、紧密粘接的关键因素。当片状银颗粒的含量小于2wt％时，制备烧结银层的过程中较少的片状银颗粒不能有效的改善纳米银颗粒烧结时出现的尺寸收缩过大的问题，同时制得的烧结银层中也会由于缺少足量的导热通道而使增强导热的作用不明显；当片状银颗粒的含量大于20wt％时，在烧结过程中片状银颗粒基本不参与烧结，它们之间会存在较多孔隙，出现烧结银层整体致密度差的问题。当片状银颗粒的含量为2～20wt％时，优选5-15wt％，更优选7-10wt％，片状银颗粒的引入提高了烧结银层的粘结性能和导热能力。优选的，烧结银层103的热导率为80-250W/(m·k)，厚度为2-30um。
在本申请中，基板104可以为热稳定性和导热率高的金属基板或陶瓷基板。本发明中首选热导率高，价格便宜，强度较好的铜基板，当采用铜基板时，对铜基板的表面经过打磨加工后，可以采用蒸镀或溅射的方式镀上一层Au层保护层，保护铜基板的表面不被氧化腐蚀，Au层保护层的厚度优选为0.01um～0.1um。
需要说明的是，铜金属作为基板104具有非常好的热导率，而选择AlN或SiC等陶瓷基板，主要是考虑到发光陶瓷层与陶瓷基板的热膨胀系数接近，使波长转换装置的可靠性更高。虽然陶瓷作基板时热导率低于铜基板、散热能力有所下降，但是其高可靠性可以应用于很多高精密的光源。
下面结合具体实施例中的制备方法和制得的波长转换装置对本申请作进一步详细说明。以下实施例仅对本申请进行进一步说明，不应理解为对本申请的限制。
实施例一
如图1所示，在本实施例的波长转换装置100中包括依次叠置的Al 2O 3封装YAG:Ce荧光粉形成的发光陶瓷层101、Al 2O 3过渡层101b、银反射膜102、Ni防止扩散层102a、烧结银层103、表面镀金的铜基板104。波长转换装置100的具体制备方法如下：
步骤1：制备发光层，并对所述发光层的表面进行抛光
将Al 2O 3粉末、YAG:Ce荧光粉颗粒、MgO粉末助剂和Y 2O 3粉末助剂混合后，烘干粉碎获得粉体，粉体装入石墨模具中，在SPS中烧结成块，然后经过退火、切割、研磨抛加工，得到厚度约50um～250um的发光陶瓷层101。
将加工到一定厚度的陶瓷单面抛光，抛光精度达到粗糙度15nm以内，表面观感为镜面。
步骤2：发光陶瓷层的镀膜
将发光陶瓷层101放置于电子束蒸镀机内，通过Al靶挥发后与O 2反应，在发光陶瓷层101抛光的表面上沉积一层Al 2O 3过渡层101b，厚度约10～200nm。
再将上述样品取出放入磁控溅射镀膜机内，在Al 2O 3过渡层101b上先镀一层Ag反射膜102，膜层要求结晶均匀，没有异常堆叠，其厚度约10nm～1um，能够提供良好的反射性能；然后同样在磁控溅射镀膜机内，更换靶头，在Ag反射膜102上镀一层Ni防止扩散层102a，Ni层无需太厚，其厚度约10nm～500nm，主要起到防止Ag原子扩散的作用。
镀膜后的发光陶瓷层101分切为5x5mm 2大小，用于后续的粘接。
步骤3：铜基板的制备
将铜基板104加工成面积为20x20mm 2、厚度为3mm的基板，基板边缘留有若干个螺孔，以便与其他载体螺丝紧固。铜基板104表面经过打磨加工后，用蒸镀或溅射的方式镀上一层Au层，厚度约0.01um～0.1um。
步骤4：镀膜发光陶瓷层与铜基板的烧结结合
在铜基板104上刷涂混合有纳米球形银颗粒和大尺寸片状银颗粒的银浆，银浆中含少量有机溶剂，大尺寸片状银颗粒的含量为10wt％。刷涂银浆后，发光陶瓷层101镀膜的一面盖于银浆之上，再用治具加压压紧，然后在150℃～300℃之间加热、优选在200℃-250℃；此时，纳米球形银颗粒熔融，但大尺寸片状银颗粒并不融化，纳米球形银颗粒熔融后将片状银的大颗粒融合连接在一起。形成的烧结银层应力小、粘接性能好，同时内部孔洞较少，大颗粒的片状银相互面接触形成更有效的导热通道，导热性能好。烧结银层热导率为250W/(m·k)，具有优良的热导率；烧结银层的厚度约为2um～30um，使发光陶瓷层101和铜基板104 紧密连接在一起，得到如图1所示的波长转换装置100。
实施例二
如图2所示，本实施例的波长转换装置200与实施例一中的波长转换装置100相似，包括依次叠置的增透膜201a、发光陶瓷层201、Al 2O 3过渡层201b、银反射膜202、Ni防止扩散层202a、烧结银层203和AlN陶瓷基板204。波长转换装置200的具体制备方法如下：
步骤1：制备发光层，并对所述发光层的双面进行抛光
将Al 2O 3粉末、YAG:Ce荧光粉颗粒、MgO粉末助剂和Y 2O 3粉末助剂混合后，烘干粉碎获得粉体，粉体装入石墨模具中，在SPS中烧结成块，然后经过退火、切割、研磨抛加工，得到厚度约50um～250um的发光陶瓷层201。
将加工到一定厚度的陶瓷双面抛光，抛光精度达到粗糙度15nm以内，表面观感为镜面。
步骤2：发光陶瓷层的镀膜
将发光陶瓷层201放置于电子束蒸镀机内，通过Al靶挥发后与O 2反应，在发光陶瓷层201抛光的一个表面上沉积一层Al 2O 3过渡层201b，厚度约10～200nm。
再将上述样品取出放入磁控溅射镀膜机内，在Al 2O 3过渡层201b上先镀一层Ag反射膜202，膜层要求结晶均匀，没有异常堆叠，其厚度约10nm～1um，能够提供良好的反射性能；然后同样在磁控溅射镀膜机内，更换靶头，在Ag反射膜202上镀一层Ni防止扩散层202a，Ni层无需太厚，其厚度约10nm～500nm，主要起到防止Ag原子扩散的作用。
接着在发光陶瓷层201的另一个抛光的表面上(本实施例中发光陶瓷层201的上表面)镀上一层增透AR膜201a，其厚度约为0.01-0.1um，以提高出光效率。
镀膜后的发光陶瓷层101分切为5x5mm 2大小，用于后续的粘接。
步骤3：陶瓷基板的制备
选用高热导率的AlN陶瓷基板，其热导率大于100W/(m·k)，在另一些实施例中也可以选择SiC陶瓷基板。
将AlN陶瓷基板加工成面积10x10mm 2、厚度为1～3mm的基板，表
波长转换装置及其制备方法
技术领域
本发明涉及照明和投影技术领域，特别是涉及一种波长转换装置及其制备方法，以及采用该波长转换装置的发光装置。
背景技术
随着显示和照明技术的发展，原始的LED或卤素灯泡作为光源越来越不能满足显示和照明高功率和高亮度的需求。采用固态光源如LD(Laser Diode，激光二极管)发出的激发光以激发波长转换材料的方法能够获得各种颜色的可见光，该技术越来越多的应用于照明和显示中。这种技术具有效率高、能耗少、成本低、寿命长的优势，是现有白光或者单色光光源的理想替代方案。
现有技术中波长转换装置在采用激光光源照射激发时，激光连续照射使波长转换装置的工作环境十分苛刻；为了经受住激光的连续照射，防止出现波长转换过程中发光层产生的大量热量无法排除、使自身温度快速提高而导致热淬灭的问题，发光层的主体材料已经从传统的有机材料发展到导热、耐热更好的玻璃、陶瓷等无机材料。
对于波长转换装置整体的导热性能和发光效率来说，发光层到基板的热传导通道是否通畅也是一个关键因素。目前发光层和基板之间的连接一般采用焊接层或烧结银层，其中烧结银层相比于焊接层的导热能力更好，但是也存在一些问题，例如：
在有机银浆烧结形成烧结银层的过程中，特别是在4*4mm 2以上的大尺寸封装上，有机银浆中间区域的有机溶剂挥发困难，纳米球形银颗粒在烧结时容易造成收缩尺寸过大、应力较大，造成烧结银层粘结性下降、容易脱落等问题；同时烧结过程中形成了较多的孔隙，使得纳米球形银颗粒间接触面积减少，降低了导热性能。
因而需要开发一种整体可靠性好、导热散热性能优异的波长转换装 置。
发明内容
针对上述现有技术存在的缺陷，本发明提供了一种整体装置可靠性高、导热散热性能好、发光效率高的波长转换装置及其制备方法，该波长转换装置能够适用于大功率激光连续照射。
本发明提供了一种波长转换装置，包括依次叠置的发光层、反射膜、烧结银层和基板；所述发光层将激发光转换成不同波长的出射光，所述反射膜镀覆在所述发光层上、用于反射从所述发光层出射的所述出射光；所述烧结银层连接所述发光层和所述基板，所述烧结银层中包含相互之间通过面接触连接的片状银颗粒。
本发明的技术方案中，通过将纳米球形银颗粒和片状银颗粒混合烧结，纳米球形银颗粒融化而将片状银颗结合起来形成烧结银层。在烧结银层中大尺寸片状银颗粒改善了烧结银浆的收缩、减少了烧结应力，提高了烧结银层的粘接性能；同时，烧结银层中的大尺寸片状银颗粒相互之间是面接触连接的，大尺寸片状银颗粒本身作为导热通道以及相互之间的面接触传热作用很好的提高了烧结银层的导热性能。
优选的，所述烧结银层的热导率为80-250W/(m·k)。
优选的，所述烧结银层中片状银颗粒的含量为2-20wt％，优选5-15wt％，更优选7-10wt％。
优选的，所述发光层为发光陶瓷层，陶瓷材料制成的发光层具有耐热、导热性能优异的特点。
优选的，所述反射膜为银反射膜，银反射膜具有致密、高反射率的特点。
优选的，在所述发光陶瓷层和所述银反射膜之间设置一过渡层，过渡层增强了发光陶瓷层和银反射膜之间的结合力，过渡层可以为Al 2O 3层或SiO 2层；另外，在所述发光陶瓷层和所述银反射膜之间也可以设置依次层叠在所述银反射膜上的高折射率介质膜和低折射率介质膜的交替膜层，例如高折射率的SiO 2介质膜和低折射率的TiO 2介质膜，整个膜层既可以起到增加反射的作用，也可以作为银反射膜与发光陶瓷层之 间的过渡层，增强Ag膜与发光陶瓷层的结合。
优选的，在所述银反射膜与所述烧结银层之间设置一防止扩散层，防止扩散层可以为Ni层，主要是防止银反射膜中Ag原子的扩散，保证银反射膜具有足够的反射率。
优选的，所述基板可以选择具有承载能力、导热率高的基板，例如金属或陶瓷基板。
在一些实施例中，铜金属作为基板具有非常好的热导率，而选择AlN或SiC等陶瓷基板主要是为了减轻热胀冷缩时因发光陶瓷层与金属基板的热膨胀系数差异带来的应力，使波长转换装置的可靠性更高。虽然陶瓷作基板时热导率低于铜基板、散热能力有所下降，但是其高可靠性可以应用于很多高精密的光源。
本发明还提供了一种发光装置，包括激发光源及上述波长转换装置，该发光装置适用于照明和投影领域。
另一方面，本发明还提供了一种波长转换装置的制备方法，其包括以下步骤：
步骤1：制备发光层，并对所述发光层的表面进行抛光；
步骤2：通过物理溅射或蒸镀工艺在所述发光层抛光的表面上形成反射膜；
步骤3：将混合有纳米球形银颗粒和片状银颗粒的银浆涂敷在基板的一个表面上；
步骤4：将所述发光层镀覆有反射膜的一面叠置在所述基板的涂敷有所述银浆的表面上；
步骤5：对整个装置进行烧结。
优选的，步骤3中所述银浆中片状银颗粒的含量为2-20wt％，优选5-15wt％，更优选7-10wt％。
优选的，步骤1中制备的发光层为发光陶瓷层。
优选的，步骤2中，通过物理溅射或蒸镀工艺在所述发光陶瓷层抛光的表面上形成的反射膜为银反射膜。更进一步的，在步骤2之前，还包括在所述发光陶瓷层抛光的表面上通过物理溅射或蒸镀形成一层过渡层，过渡层可以为Al 2O 3层或SiO 2层；更进一步的，在步骤2之前， 还包括通过物理溅射或蒸镀形成的依次层叠在所述发光陶瓷层抛光的表面上的低折射率介质膜和高折射率介质膜的交替膜层，例如高折射率的SiO 2介质膜和低折射率的TiO 2介质膜。更进一步的，在步骤2之后，还包括在所述银反射膜上通过物理溅射或蒸镀形成一层防止扩散层，防止扩散层可以是金属Ni层。
优选的，步骤3中所述基板选择金属基板或陶瓷基板，金属基板可以为铜金属基板，陶瓷基板可以为AlN或SiC基板。
与现有技术相比，本发明包括如下有益效果：
本发明的波长转换装置为了获得高效的导热散热能力，其发光层和散热基板之间采用热导率极高的烧结银层连接导通，烧结银层是通过将纳米球形银颗粒和大尺寸片状银颗粒混合烧结、纳米球形银颗粒融化而将大尺寸片状银颗结合起来而形成的。制得的烧结银层中大尺寸片状银颗粒改善了烧结银浆的收缩、减少了烧结应力，提高了烧结银层的粘接性能；同时，烧结银层中的大尺寸片状银颗粒相互之间是面接触的，大尺寸银颗粒本身作为导热通道以及相互之间的面接触传热作用很好的提高了烧结银层的导热性能。
附图说明
附图仅用于示出具体实施例的目的，而并不认为是对本发明的限制。
图1为本发明实施例一的波长转换装置的结构示意图。
图2为本发明实施例二的波长转换装置的结构示意图。
图3为本发明实施例三的波长转换装置的结构示意图。
图4为本发明的烧结银层的结构示意图。
具体实施方式
下面结合附图和实施方式对本发明实施例进行详细说明。
正如背景技术所述，目前的烧结银在器件封装方面主要是应用在小尺寸封装上，在4*4mm 2以上尺寸面积上的应用还是相对较少。在大尺寸封装上，烧结银在烧结过程中中间区域的有机溶剂挥发较困难，且纳米银颗粒在烧结时容易造成收缩尺寸过大、应力较大，影响封装性能(如 粘接性下降)；同时，烧结银层中形成了较多的孔隙，使得纳米银颗粒间接触面积减少，降低了导热性能。
本发明通过混合烧结纳米银颗粒和大尺寸片状银颗粒，制得性能优异的烧结银层，将其应用为波长转换装置中发光层和基板之间的导热粘接层，获得了装置可靠性高、导热效果好的波长转换装置。
请参考图1，本发明提供了一种波长转换装置100，其包括依次叠置的发光层101、反射膜102、烧结银层103和基板104。其中，发光层101将激发光转换成不同波长的出射光，反射膜102镀覆在发光层101上、用于反射从发光层101出射的出射光；烧结银层103连接发光层101和基板104，烧结银层103中包含相互之间通过面接触连接的片状银颗粒。
在本申请中，发光层101通常是具有良好散热、耐热性能的发光陶瓷层，作为其中的发光材料即波长转换材料，其成分没有特别限定，例如可以为铝酸盐荧光粉、卤磷酸荧光粉、石榴石系荧光粉或量子点中的一种。特别的，当波长转换材料选择YAG石榴石系荧光粉时，发光陶瓷层101可以为YAG纯相发光陶瓷，也可以为YAG与Al 2O 3粉或AlN粉混合烧制的复相发光陶瓷。在一具体实施例中可以采用Al 2O 3封装YAG：Ce荧光粉形成发光陶瓷层，优选的，在综合考虑发光效率和导热率的情况下，发光陶瓷层的厚度约为50-250um。
进一步的，在发光层101面向入射光的上表面还可以设置一增透膜101a。增透膜101a可起到增透减反的作用，即减少入射激发光在发光层101上表面的反射率，增加激发光在发光层101的透过率，有利于提升发光层101表面的出光效率。在一具体实施例中，增透膜101a优选厚度为0.01um～0.1um。
在本申请中，镀覆于发光层101上的反射膜102可以为银反射膜，其一般采用物理溅射或蒸镀等技术镀覆于发光层101的一个表面上，制得的银反射膜具有致密、高反射率的特点，优选银反射膜的厚度为10nm～1um。
进一步的，对于发光陶瓷层和银反射膜来说，为了增强两者之间的结合力，可以先在发光陶瓷层上先镀上一层过渡层101b后再镀银反射 膜，这里的过渡层101b可以为Al 2O 3层或SiO 2层；另外，也可以在发光陶瓷层和银反射膜之间设置依次层叠在发光陶瓷层上的低折射率介质膜和高折射率介质膜的交替膜层，例如高折射率的SiO 2介质膜和低折射率的TiO 2介质膜，整个膜层既可以起到增加反射的作用，也可以作为银反射膜与发光陶瓷层之间的过渡层，增强Ag膜与发光陶瓷层的结合。过渡层101b的厚度约为10-200nm。
另外，为了防止银反射膜中Ag原子的扩散，保证银反射膜具有足够的反射率，可以在银反射膜上镀上一层防止扩散层102a后再与烧结银层103连接；防止扩散层102a可以为金属Ni层，厚度约为10-500nm。
对于本申请的烧结银层103来说，其是由纳米球形银颗粒和大尺寸片状银颗粒烧结制得。纳米球形的银颗粒在各个方向的曲率半径较为一致，易于在烧结过程中融化流动；而大尺寸片状银颗粒一般为长方体状或扁平状，其在长度方向或扁平方向的长度远大于其在厚度方向的长度，在烧结过程中不易融化，阻碍材料过度收缩；这样，在烧结过程中，大尺寸片状银颗粒之间相互支撑，其间由纳米球形银颗粒熔融粘接，最终形成为包含卡片搭桥结构的、相互之间面接触的大尺寸片状银颗粒的烧结银层103，其各片状银颗粒间的接触面积较大，更好地形成导热网络。例如，烧结银层103可以为层间堆叠的片状银之间由融化的银粘接的结构，如图4所示，其中1表示大尺寸片状银颗粒，2表示它们之间融化的起连接作用的银。
对于烧结银层的原料银浆来说，其是混合有纳米球形银颗粒和大尺寸片状银颗粒的有机银浆，其中含有少量有机溶剂，片状银颗粒的含量为2-20wt％，优选5-15wt％，更优选7-10wt％，片状银颗粒的尺寸为微米级以上。在烧结过程中，由于片状银颗粒的尺寸较大，相比于纳米球形银颗粒烧结活性很小，在150℃-300℃(优选在200℃-250℃)温度烧结时，其难以参与烧结，几乎能维持其形状，纳米球形银颗粒烧结融化将片状银颗粒结合连接，形成的烧结银层中片状银颗粒的含量几乎不变。大尺寸片状银颗粒的引入相对于只有纳米球形银颗粒来说，可以很好地解决烧结过程中纳米球形银颗粒尺寸收缩过大、应力较大的问题，改善烧结银层的粘结性能；同时片状银颗粒间是面接触，相比于纳米球形银 颗粒间的球形点接触，可以很好的提高其导热性能。
如上所述，在烧结银层的原料银浆中，其大尺寸片状银颗粒的添加量是制得的烧结银层实现高效导热、紧密粘接的关键因素。当片状银颗粒的含量小于2wt％时，制备烧结银层的过程中较少的片状银颗粒不能有效的改善纳米银颗粒烧结时出现的尺寸收缩过大的问题，同时制得的烧结银层中也会由于缺少足量的导热通道而使增强导热的作用不明显；当片状银颗粒的含量大于20wt％时，在烧结过程中片状银颗粒基本不参与烧结，它们之间会存在较多孔隙，出现烧结银层整体致密度差的问题。当片状银颗粒的含量为2～20wt％时，优选5-15wt％，更优选7-10wt％，片状银颗粒的引入提高了烧结银层的粘结性能和导热能力。优选的，烧结银层103的热导率为80-250W/(m·k)，厚度为2-30um。
在本申请中，基板104可以为热稳定性和导热率高的金属基板或陶瓷基板。本发明中首选热导率高，价格便宜，强度较好的铜基板，当采用铜基板时，对铜基板的表面经过打磨加工后，可以采用蒸镀或溅射的方式镀上一层Au层保护层，保护铜基板的表面不被氧化腐蚀，Au层保护层的厚度优选为0.01um～0.1um。
需要说明的是，铜金属作为基板104具有非常好的热导率，而选择AlN或SiC等陶瓷基板，主要是考虑到发光陶瓷层与陶瓷基板的热膨胀系数接近，使波长转换装置的可靠性更高。虽然陶瓷作基板时热导率低于铜基板、散热能力有所下降，但是其高可靠性可以应用于很多高精密的光源。
下面结合具体实施例中的制备方法和制得的波长转换装置对本申请作进一步详细说明。以下实施例仅对本申请进行进一步说明，不应理解为对本申请的限制。
实施例一
如图1所示，在本实施例的波长转换装置100中包括依次叠置的Al 2O 3封装YAG:Ce荧光粉形成的发光陶瓷层101、Al 2O 3过渡层101b、银反射膜102、Ni防止扩散层102a、烧结银层103、表面镀金的铜基板104。波长转换装置100的具体制备方法如下：
步骤1：制备发光层，并对所述发光层的表面进行抛光
将Al 2O 3粉末、YAG:Ce荧光粉颗粒、MgO粉末助剂和Y 2O 3粉末助剂混合后，烘干粉碎获得粉体，粉体装入石墨模具中，在SPS中烧结成块，然后经过退火、切割、研磨抛加工，得到厚度约50um～250um的发光陶瓷层101。
将加工到一定厚度的陶瓷单面抛光，抛光精度达到粗糙度15nm以内，表面观感为镜面。
步骤2：发光陶瓷层的镀膜
将发光陶瓷层101放置于电子束蒸镀机内，通过Al靶挥发后与O 2反应，在发光陶瓷层101抛光的表面上沉积一层Al 2O 3过渡层101b，厚度约10～200nm。
再将上述样品取出放入磁控溅射镀膜机内，在Al 2O 3过渡层101b上先镀一层Ag反射膜102，膜层要求结晶均匀，没有异常堆叠，其厚度约10nm～1um，能够提供良好的反射性能；然后同样在磁控溅射镀膜机内，更换靶头，在Ag反射膜102上镀一层Ni防止扩散层102a，Ni层无需太厚，其厚度约10nm～500nm，主要起到防止Ag原子扩散的作用。
镀膜后的发光陶瓷层101分切为5x5mm 2大小，用于后续的粘接。
步骤3：铜基板的制备
将铜基板104加工成面积为20x 20mm 2、厚度为3mm的基板，基板边缘留有若干个螺孔，以便与其他载体螺丝紧固。铜基板104表面经过打磨加工后，用蒸镀或溅射的方式镀上一层Au层，厚度约0.01um～0.1um。
步骤4：镀膜发光陶瓷层与铜基板的烧结结合
在铜基板104上刷涂混合有纳米球形银颗粒和大尺寸片状银颗粒的银浆，银浆中含少量有机溶剂，大尺寸片状银颗粒的含量为10wt％。刷涂银浆后，发光陶瓷层101镀膜的一面盖于银浆之上，再用治具加压压紧，然后在150℃～300℃之间加热、优选在200℃-250℃；此时，纳米球形银颗粒熔融，但大尺寸片状银颗粒并不融化，纳米球形银颗粒熔融后将片状银的大颗粒融合连接在一起。形成的烧结银层应力小、粘接性能好，同时内部孔洞较少，大颗粒的片状银相互面接触形成更有效的导热通道，导热性能好。烧结银层热导率为250W/(m·k)，具有优良的热导率；烧结银层的厚度约为2um～30um，使发光陶瓷层101和铜基板104 紧密连接在一起，得到如图1所示的波长转换装置100。
实施例二
如图2所示，本实施例的波长转换装置200与实施例一中的波长转换装置100相似，包括依次叠置的增透膜201a、发光陶瓷层201、Al 2O 3过渡层201b、银反射膜202、Ni防止扩散层202a、烧结银层203和AlN陶瓷基板204。波长转换装置200的具体制备方法如下：
步骤1：制备发光层，并对所述发光层的双面进行抛光
将Al 2O 3粉末、YAG:Ce荧光粉颗粒、MgO粉末助剂和Y 2O 3粉末助剂混合后，烘干粉碎获得粉体，粉体装入石墨模具中，在SPS中烧结成块，然后经过退火、切割、研磨抛加工，得到厚度约50um～250um的发光陶瓷层201。
将加工到一定厚度的陶瓷双面抛光，抛光精度达到粗糙度15nm以内，表面观感为镜面。
步骤2：发光陶瓷层的镀膜
将发光陶瓷层201放置于电子束蒸镀机内，通过Al靶挥发后与O 2反应，在发光陶瓷层201抛光的一个表面上沉积一层Al 2O 3过渡层201b，厚度约10～200nm。
再将上述样品取出放入磁控溅射镀膜机内，在Al 2O 3过渡层201b上先镀一层Ag反射膜202，膜层要求结晶均匀，没有异常堆叠，其厚度约10nm～1um，能够提供良好的反射性能；然后同样在磁控溅射镀膜机内，更换靶头，在Ag反射膜202上镀一层Ni防止扩散层202a，Ni层无需太厚，其厚度约10nm～500nm，主要起到防止Ag原子扩散的作用。
接着在发光陶瓷层201的另一个抛光的表面上(本实施例中发光陶瓷层201的上表面)镀上一层增透AR膜201a，其厚度约为0.01-0.1um，以提高出光效率。
镀膜后的发光陶瓷层101分切为5x5mm 2大小，用于后续的粘接。
步骤3：陶瓷基板的制备
选用高热导率的AlN陶瓷基板，其热导率大于100W/(m·k)，在另一些实施例中也可以选择SiC陶瓷基板。
将AlN陶瓷基板加工成面积10x10mm 2、厚度为1～3mm的基板，表 面经过打磨抛光加工后，在其表面用覆铜工艺做一层铜层，再用蒸镀或溅射的方式镀上一层Au层，Au厚度约0.01～0.1um。
步骤4：镀膜发光陶瓷层与陶瓷基板的烧结结合
在AlN陶瓷基板204上刷涂混合有纳米球形银颗粒和大尺寸片状银颗粒的银浆，银浆中含少量有机溶剂，大尺寸片状银颗粒的含量为2-20wt％。刷涂银浆后，发光陶瓷层201镀覆银反射膜102的一面盖于银浆之上，再用治具加压压紧，然后在150℃～300℃之间加热、优选在200℃-250℃；此时，纳米球形银颗粒熔融，但大尺寸片状银颗粒并不融化，纳米球形银熔融后将片状银的大颗粒融合连接在一起。形成的烧结银层203应力小、粘接性能好，同时内部孔洞较少，大颗粒的片状银相互面接触形成更有效的导热通道，导热性能好。烧结银层203热导率为80-250W/(m·k)，具有优良的热导率；烧结银层203的厚度约为2um～30um，使发光陶瓷层201和AlN陶瓷基板204紧密连接在一起，得到如图2所示的波长转换装置200。
与实施例一相比，实施例二采用AlN陶瓷基板替换铜基板，虽然AlN陶瓷基板的热导率低于铜基板、散热能力有所下降，但是其与发光陶瓷层的热膨胀系数更接近，获得的波长转换装置200可靠性更高，可适用于很多高精密的光源。
实施例三
如图3所示，本实施例的波长转换装置300与实施例一中的波长转换装置100相似，包括依次叠置的增透膜301a、发光陶瓷层301、高低折射率交替镀膜介质层301b、银反射膜302、Ni防止扩散层302a、烧结银层303、表面镀金的铜基板304。波长转换装置300的制备方法具体为：
步骤1：制备发光层，并对所述发光层的双面进行抛光
将Al 2O 3粉末、YAG:Ce荧光粉颗粒、MgO粉末助剂和Y 2O 3粉末助剂混合后，烘干粉碎获得粉体，粉体装入石墨模具中，在SPS中烧结成块，然后经过退火、切割、研磨抛加工，得到厚度约50um～250um的发光陶瓷层301。
将加工到一定厚度的陶瓷双面抛光，抛光精度达到粗糙度15nm以内， 表面观感为镜面。
步骤2：发光陶瓷层的镀膜
将发光陶瓷层301放置于电子束蒸镀机内，在发光陶瓷层301抛光的一个表面上交替镀膜，交替膜层为低折射率介质膜301b2和高折射率介质膜301b1，低折射率介质膜和高折射率介质膜分别为TiO 2和SiO 2，这种交替介质膜可以是2层，也可以是数十层，在本实施例三中为2层，整体厚约10nm～200nm，这个高低折射率交替镀膜介质层301b既可以起到增加反射的作用，也可增强银反射膜302与发光陶瓷层301的结合。
再将上述样品取出放入磁控溅射镀膜机内，在高低折射率交替镀膜介质层301b上先镀一层Ag反射膜302，膜层要求结晶均匀，没有异常堆叠，其厚度约10nm～1um，能够提供良好的反射性能；然后同样在磁控溅射镀膜机内，更换靶头，在Ag反射膜302上镀一层Ni防止扩散层302a，Ni层无需太厚，其厚度约10nm～500nm，主要起到防止Ag原子扩散的作用。
接着在发光陶瓷层301的另一个抛光的表面上(本实施例中发光陶瓷层301的上表面)镀上一层增透AR膜301a，其厚度约为0.01-0.1um，以提高出光效率。
镀膜后的发光陶瓷层301分切为5x5mm 2大小，用于后续的粘接。
步骤3：铜基板的制备
将铜基板304加工成面积为20x20mm 2、厚度为3mm的基板，基板边缘留有若干个螺孔，以便与其他载体螺丝紧固。铜基板304表面经过打磨加工后，用蒸镀或溅射的方式镀上一层Au层，厚度约0.01um～0.5um。
步骤4：发光陶瓷层与铜基板的结合
在铜基板304上刷涂混合有纳米球形银颗粒和大尺寸片状银颗粒的银浆，银浆中含少量有机溶剂，大尺寸片状银颗粒的含量为2-20wt％。刷涂银浆后，发光陶瓷层301镀银反射膜302的一面盖于银浆之上，再用治具加压压紧，然后在150℃～300℃之间加热、优选在200℃-250℃；此时，纳米球形银颗粒熔融，但大尺寸片状银颗粒并不融化，纳米球形银熔融后将片状银的大颗粒融合连接在一起。形成的烧结银层303应力小、粘接性能好，同时内部孔洞较少，大颗粒的片状银相互面接触形成 更有效的导热通道，导热性能好。烧结银层303热导率为80-250W/(m·k)，具有优良的热导率；烧结银层303的厚度约为2um～30um，使发光陶瓷层301和铜基板304紧密连接在一起，得到如图3所示的波长转换装置300。
实施例四
本实施例除了在步骤4烧结银层浆料中大尺寸片状银颗粒的含量为7wt％之外，其余步骤与实施例1相同，制得的烧结银层的热导率为220W/(m·k)。
实施例五
本实施例除了在步骤4烧结银层浆料中大尺寸片状银颗粒的含量为15wt％之外，其余步骤与实施例1相同，制得的烧结银层的热导率为200W/(m·k)。
实施例六
本实施例除了在步骤4烧结银层浆料中大尺寸片状银颗粒的含量为5wt％之外，其余步骤与实施例1相同，制得的烧结银层的热导率为150W/(m·k)。
实施例七
本实施例除了在步骤4烧结银层浆料中大尺寸片状银颗粒的含量为1wt％之外，其余步骤与实施例1相同，烧结过程中银层浆料面积收缩明显、制得的烧结银层的热导率小于80W/(m·k)。
实施例八
本实施例在步骤4中，当烧结银层浆料中大尺寸片状银颗粒的含量选为22wt％时，烧结过程中大颗粒的片状银之间存在空隙、整体致密度差，制得的烧结银层无法有效粘接发光层和基板。
本发明实施例还提供了一种发光装置，该发光装置包括激发光源和波长转换装置，其中波长转换装置可以具有上述各实施例中的结构与功能。该发光装置可以应用于投影系统，例如液晶显示器(LCD，Liquid Crystal Display)或数码光路处理器(DLP，Digital Light Processor)投影机；也可以应用于照明系统，例如汽车照明灯或舞台灯；也可以应用于3D显示技术领域中。
本说明书中各个实施例采用递进的方式描述，每个实施例重点说明的都是与其他实施例的不同之处，各个实施例之间相同相似部分互相参见即可。
以上所述仅为本发明的实施方式，并非因此限制本发明的专利范围，凡是利用本发明说明书及附图内容所作的等效结构或等效流程变换，或直接或间接运用在其他相关的技术领域，均同理包括在本发明的专利保护范围内。

Claims (24)

  1. 一种波长转换装置，其特征在于，包括依次叠置的发光层、反射膜、烧结银层和基板；
    所述发光层将激发光转换成不同波长的出射光，所述反射膜镀覆在所述发光层上、用于反射从所述发光层出射的所述出射光；所述烧结银层连接所述发光层和所述基板，所述烧结银层中包含相互之间通过面接触连接的片状银颗粒。
  2. 根据权利要求1所述的波长转换装置，其特征在于，所述烧结银层的热导率为80-250W/(m·k)。
  3. 根据权利要求1所述的波长转换装置，其特征在于，所述烧结银层中片状银颗粒的含量为2-20wt％。
  4. 根据权利要求1所述的波长转换装置，其特征在于，所述烧结银层中片状银颗粒的含量为5-15wt％。
  5. 根据权利要求1所述的波长转换装置，其特征在于，所述烧结银层中片状银颗粒的含量为7-10wt％。
  6. 根据权利要求1-5任一项所述的波长转换装置，其特征在于，所述发光层为发光陶瓷层。
  7. 根据权利要求6所述的波长转换装置，其特征在于，所述反射膜为银反射膜。
  8. 根据权利要求7所述的波长转换装置，其特征在于，在所述发光陶瓷层和所述银反射膜之间设置一过渡层。
  9. 根据权利要求8所述的波长转换装置，其特征在于，所述过渡层为Al 2O 3层或SiO 2层。
  10. 根据权利要求8所述的波长转换装置，其特征在于，在所述发光陶瓷层和所述银反射膜之间设置依次层叠在所述银反射膜上的高折射率介质膜和低折射率介质膜的交替膜层。
  11. 根据权利要求7所述的波长转换装置，其特征在于，在所述银反射膜与所述烧结银层之间设置有一防止扩散层。
  12. 根据权利要求1-5任一项所述的波长转换装置，其特征在于，所 述基板为金属基板或陶瓷基板。
  13. 一种发光装置，包括激发光源以及权利要求1-12任一项所述的波长转换装置。
  14. 一种波长转换装置的制备方法，其特征在于，包括以下步骤：
    步骤1：制备发光层，并对所述发光层的表面进行抛光；
    步骤2：通过物理溅射或蒸镀工艺在所述发光层抛光的表面上形成反射膜；
    步骤3：将混合有纳米银颗粒和片状银颗粒的银浆涂敷在基板的一个表面上；
    步骤4：将所述发光层镀有反射膜的一面叠置在所述基板的涂敷有所述银浆的表面上；
    步骤5：对整个装置进行烧结。
  15. 根据权利要求14所述的波长转换装置的制备方法，其特征在于，在步骤3中，所述银浆中片状银颗粒的含量为2-20wt％。
  16. 根据权利要求14所述的波长转换装置的制备方法，其特征在于，在步骤3中，所述银浆中片状银颗粒的含量为5-15wt％。
  17. 根据权利要求14所述的波长转换装置的制备方法，其特征在于，在步骤3中，所述银浆中片状银颗粒的含量为7-10wt％。
  18. 根据权利要求14-17任一项所述的波长转换装置的制备方法，其特征在于，步骤1中制备发光层为：混合陶瓷基质和发光材料粉末，然后将混合粉末压制、烧结以获得发光陶瓷层。
  19. 根据权利要求18所述的波长转换装置的制备方法，其特征在于，在步骤2中，通过物理溅射或蒸镀工艺在所述发光陶瓷层抛光的表面上形成的反射膜为银反射膜。
  20. 根据权利要求19所述的波长转换装置的制备方法，其特征在于，在步骤2之前，还包括在所述发光陶瓷层抛光的表面上通过物理溅射或蒸镀形成一层过渡层。
  21. 根据权利要求20所述的波长转换装置的制备方法，其特征在于，所述过渡层为Al 2O 3层或SiO 2层。
  22. 根据权利要求19所述的波长转换装置的制备方法，其特征在于， 在步骤2之前，还包括在所述发光陶瓷层抛光的表面上通过物理溅射或蒸镀形成的低折射率介质膜和高折射率介质膜的交替膜层。
  23. 根据权利要求19所述的波长转换装置的制备方法，其特征在于，在步骤2之后，还包括在所述银反射膜上通过物理溅射或蒸镀形成一层防止扩散层。
  24. 根据权利要求14-17任一项所述的波长转换装置的制备方法，其特征在于，步骤3中所述基板为金属基板或陶瓷基板。
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