WO2016087600A1 - Method for producing a ceramic conversion element, ceramic conversion element and optoelectronic device - Google Patents
Method for producing a ceramic conversion element, ceramic conversion element and optoelectronic device Download PDFInfo
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- WO2016087600A1 WO2016087600A1 PCT/EP2015/078559 EP2015078559W WO2016087600A1 WO 2016087600 A1 WO2016087600 A1 WO 2016087600A1 EP 2015078559 W EP2015078559 W EP 2015078559W WO 2016087600 A1 WO2016087600 A1 WO 2016087600A1
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- Prior art keywords
- ceramic
- conversion element
- pixel regions
- basic body
- reflective
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- 239000000919 ceramic Substances 0.000 title claims abstract description 159
- 238000006243 chemical reaction Methods 0.000 title claims abstract description 105
- 230000005693 optoelectronics Effects 0.000 title claims abstract description 21
- 238000004519 manufacturing process Methods 0.000 title claims abstract description 9
- 238000000034 method Methods 0.000 claims abstract description 45
- OAICVXFJPJFONN-UHFFFAOYSA-N Phosphorus Chemical compound [P] OAICVXFJPJFONN-UHFFFAOYSA-N 0.000 claims abstract description 13
- 238000004049 embossing Methods 0.000 claims abstract description 12
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- 239000000463 material Substances 0.000 claims description 14
- 238000000151 deposition Methods 0.000 claims description 10
- 230000008021 deposition Effects 0.000 claims description 10
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 9
- 229910052799 carbon Inorganic materials 0.000 claims description 9
- 239000004005 microsphere Substances 0.000 claims description 9
- 239000011224 oxide ceramic Substances 0.000 claims description 7
- 239000002002 slurry Substances 0.000 claims description 7
- 238000011049 filling Methods 0.000 claims description 6
- 230000000737 periodic effect Effects 0.000 claims description 6
- 239000004065 semiconductor Substances 0.000 claims description 5
- 239000004809 Teflon Substances 0.000 claims description 4
- 229920006362 Teflon® Polymers 0.000 claims description 4
- GWEVSGVZZGPLCZ-UHFFFAOYSA-N Titan oxide Chemical compound O=[Ti]=O GWEVSGVZZGPLCZ-UHFFFAOYSA-N 0.000 claims description 4
- TZCXTZWJZNENPQ-UHFFFAOYSA-L barium sulfate Chemical compound [Ba+2].[O-]S([O-])(=O)=O TZCXTZWJZNENPQ-UHFFFAOYSA-L 0.000 claims description 4
- TWNQGVIAIRXVLR-UHFFFAOYSA-N oxo(oxoalumanyloxy)alumane Chemical compound O=[Al]O[Al]=O TWNQGVIAIRXVLR-UHFFFAOYSA-N 0.000 claims description 4
- 238000005096 rolling process Methods 0.000 claims description 4
- OGIDPMRJRNCKJF-UHFFFAOYSA-N titanium oxide Inorganic materials [Ti]=O OGIDPMRJRNCKJF-UHFFFAOYSA-N 0.000 claims description 4
- 238000005229 chemical vapour deposition Methods 0.000 claims description 3
- 238000004070 electrodeposition Methods 0.000 claims description 3
- 238000000313 electron-beam-induced deposition Methods 0.000 claims description 3
- 238000009713 electroplating Methods 0.000 claims description 3
- 238000001704 evaporation Methods 0.000 claims description 3
- 230000008020 evaporation Effects 0.000 claims description 3
- 229910052574 oxide ceramic Inorganic materials 0.000 claims description 3
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- 238000007741 pulsed electron deposition Methods 0.000 claims description 3
- 238000004062 sedimentation Methods 0.000 claims description 3
- 238000004544 sputter deposition Methods 0.000 claims description 3
- 239000002131 composite material Substances 0.000 claims description 2
- 239000002086 nanomaterial Substances 0.000 claims description 2
- 239000004038 photonic crystal Substances 0.000 claims description 2
- 239000013079 quasicrystal Substances 0.000 claims description 2
- 239000002356 single layer Substances 0.000 claims description 2
- 238000004549 pulsed laser deposition Methods 0.000 claims 2
- 230000005670 electromagnetic radiation Effects 0.000 description 9
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- 229910052788 barium Inorganic materials 0.000 description 7
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- 229910052688 Gadolinium Inorganic materials 0.000 description 3
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- 229910052727 yttrium Inorganic materials 0.000 description 3
- 239000000853 adhesive Substances 0.000 description 2
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- 150000004645 aluminates Chemical class 0.000 description 2
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- 229910003460 diamond Inorganic materials 0.000 description 2
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- 230000003628 erosive effect Effects 0.000 description 2
- 229910001938 gadolinium oxide Inorganic materials 0.000 description 2
- 229940075613 gadolinium oxide Drugs 0.000 description 2
- CMIHHWBVHJVIGI-UHFFFAOYSA-N gadolinium(iii) oxide Chemical compound [O-2].[O-2].[O-2].[Gd+3].[Gd+3] CMIHHWBVHJVIGI-UHFFFAOYSA-N 0.000 description 2
- 239000011521 glass Substances 0.000 description 2
- 229910003443 lutetium oxide Inorganic materials 0.000 description 2
- 150000004767 nitrides Chemical class 0.000 description 2
- MPARYNQUYZOBJM-UHFFFAOYSA-N oxo(oxolutetiooxy)lutetium Chemical compound O=[Lu]O[Lu]=O MPARYNQUYZOBJM-UHFFFAOYSA-N 0.000 description 2
- SIWVEOZUMHYXCS-UHFFFAOYSA-N oxo(oxoyttriooxy)yttrium Chemical compound O=[Y]O[Y]=O SIWVEOZUMHYXCS-UHFFFAOYSA-N 0.000 description 2
- 238000003825 pressing Methods 0.000 description 2
- 229910052782 aluminium Inorganic materials 0.000 description 1
- XAGFODPZIPBFFR-UHFFFAOYSA-N aluminium Chemical compound [Al] XAGFODPZIPBFFR-UHFFFAOYSA-N 0.000 description 1
- JNDMLEXHDPKVFC-UHFFFAOYSA-N aluminum;oxygen(2-);yttrium(3+) Chemical compound [O-2].[O-2].[O-2].[Al+3].[Y+3] JNDMLEXHDPKVFC-UHFFFAOYSA-N 0.000 description 1
- 238000013459 approach Methods 0.000 description 1
- 239000006229 carbon black Substances 0.000 description 1
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- 238000002844 melting Methods 0.000 description 1
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- 229910052755 nonmetal Inorganic materials 0.000 description 1
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- 238000010345 tape casting Methods 0.000 description 1
- 229910019901 yttrium aluminum garnet Inorganic materials 0.000 description 1
Classifications
-
- 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
- H01L33/505—Wavelength conversion elements characterised by the shape, e.g. plate or foil
-
- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01L—SEMICONDUCTOR DEVICES NOT COVERED BY CLASS H10
- H01L25/00—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof
- H01L25/03—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes
- H01L25/04—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers
- H01L25/075—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00
- H01L25/0753—Assemblies consisting of a plurality of individual semiconductor or other solid state devices ; Multistep manufacturing processes thereof all the devices being of a type provided for in the same subgroup of groups H01L27/00 - H01L33/00, or in a single subclass of H10K, H10N, e.g. assemblies of rectifier diodes the devices not having separate containers the devices being of a type provided for in group H01L33/00 the devices being arranged next to each other
Definitions
- the present application is directed to a method for produci a ceramic conversion element, a ceramic conversion element and an optoelectronic device with a ceramic conversion element .
- Ceramic conversion elements are, for example, described in WO 2014/090893 Al, US 8, 492, 182 B2 and US 2011/0210658 Al .
- WO 2013/164737 Al describes a pixelated chip with a plurality of separated conversion elements, while S. Zhang et al . , CMOS-controlled color-tunable smart display, IEEE
- a ceramic basic body in the green state comprises a phosphor, which converts light of a first wavelength range into light of a second wavelength range.
- the second wavelength range is different from the first wavelength range and comprises preferably longer wavelengths than the first wavelength range .
- a ceramic basic body in the green state can be manufactured as described in the following. First of all, a slurry is produced by mixing ceramic phosphor particles with an organic binder. Then the ceramic basic body is preformed from the slurry by a ceramic-forming method such as tape casting, injection molding, slip casting, dry pressing, isostatic pressing or hot isostatic pressing. The preformed ceramic basic body in the green state has preferably the form of a cuboid or a plate.
- the ceramic basic body in the green state is structured such that pixel regions are formed within the ceramic basic body.
- the pixel regions are separated from each other by grooves, while the ceramic basic body comprises a continuously connecting part, which connects the pixel regions along a main surface of the ceramic basic body.
- the structuring of the ceramic basic body in the green state can be performed by laser structuring, such as laser
- the ceramic basic body in the green state can be pixelated by laser structuring and then be sintered. Since the work piece shrinks when going from the green state to the sintered state, a benefit of this approach is that the structures can be made approximately 15% to 20% smaller than what is possible by directly scribing in the sintered state. In particular, the width of the grooves between the pixel regions and/or the width of the pixel regions itself can be made approximately 15% to 20% smaller than what is possible by directly scribing in the sintered state.
- laser structuring such as laser scribing is a preferred method for structuring the ceramic basic body into pixel regions in the green state.
- micro- embossing can be used as a method for structuring the ceramic basic body in the green state. While in the green state, the ceramic basic body is embossed with a stamp that transfers the pattern of the stamp within the ceramic basic body.
- the embossing can be accomplished in a number of ways such as with a hot press, a stamp or a roller, for example a nip or a gravure .
- Laser structuring has the advantage over hot embossing for structuring the ceramic basic body that the handling is easier. Further, the yield is better when using laser
- embossing which requires a new stamp for every new pattern of pixel regions, laser structuring of different patterns can be performed with the same tool.
- a further method for structuring the ceramic basic body in the green state is gravure rolling.
- Gravure rolling has the advantage over hot embossing with a stamp that the green tape is easier released.
- the ceramic basic body is sintered after the structuring. If the ceramic basic body in the green state is sintered, it shrinks by approximately 15% to 20%.
- the ceramic basic body is in the green state when structured.
- a ceramic basic body is already provided in a sintered state and then structured. Hot-embossing is not suited to structure the ceramic basic body in the sintered state.
- the ceramic basic body in the sintered state also has preferably the form of a cuboid or a plate.
- the ceramic basic body in the sintered state comprises a phosphor, which converts light of a first wavelength range into light of a second wavelength range.
- the ceramic basic body consists of the phosphor.
- the sintered ceramic basic body is structured such that pixel regions are formed within the sintered ceramic basic body.
- the pixel regions are separated from each other by grooves, while the sintered ceramic basic body further comprises a continuously connecting part, which connects the pixel regions along a main surface of the sintered basic body.
- the sintered ceramic basic body can be structured by laser structuring, mechanical manipulation such as sawing or grinding, or erosion methods such as sand-blasting or jet cutting.
- a sawing method diamond sawing can be used, while as a jet cutting method, water-jet cutting can be used.
- a basic ceramic body in the green state or in the sintered state is provided in a first step and then structured.
- the printing can be performed directly or with the help of a template.
- the mold has the desired structure of the
- the structured ceramic conversion element in the green state is sintered. During the sintering step the ceramic conversion element and in particular the structure of the conversion element shrinks by approximately 15% to 20%, limits included. According to a further aspect of the invention sidewalls of the pixel regions are coated with a reflective and/or
- the reflective and/or an absorbing material forms a reflective and/or absorbing layer on the sidewalls.
- the sidewalls are coated with a mixture of an absorbing material and a reflective material.
- the absorbing material of the mixture absorbs electromagnetic radiation in the blue spectral range and the reflecting material of the mixture reflects electromagnetic radiation in the yellow spectral range or vice versa.
- the reflective and/or absorbing layer can be deposited by one of the following methods: evaporation, pulsed laser
- the coating of the sidewalls of the pixel regions is performed in the sintered state of the ceramic conversion element.
- a metal such as silver or aluminum can be used.
- a carbon filled polymer or a wavelength selective absorber can be used as a reflective material for the layer.
- a carbon filled polymer is typically suited to absorb electromagnetic radiation of a broad range of visible wavelengths.
- a wavelength selective absorber is preferably suited to absorb electromagnetic radiation of the blue spectral range and to transmit
- the wavelength selective absorber is
- the wavelength selective absorber absorbs only electromagnetic radiation of the blue spectral range or electromagnetic radiation of the yellow spectral range. This helps to prevent cross-talk between neighboured pixel
- a polymer filled with an absorbing substance such as carbon black or a pigment
- an absorbing substance such as carbon black or a pigment
- the following materials are suited to be used as absorbing material: nano-structured carbon, silicon, a metal, a non-metal.
- the top surfaces of the pixel regions of the conversion element are covered during the deposition of the reflective and/or absorbing layer, for example with a mask. In such a way the top surfaces, which might be intended to be light-exit surfaces of the finished ceramic conversion element, are free from the reflective or absorbing material of the layer with advantage.
- the top surfaces of the pixel regions which are intended to be light exit surfaces, can be cleaned after the deposition of the reflective and/or absorbing layer, for example by grinding and/or polishing.
- the grooves between the pixel regions can be filled with a reflective and/or absorbing material.
- the grooves are filled completely with the reflective and/or absorbing material, such that it is arranged in a flush manner with the top surfaces of the pixel regions. If the grooves are filled completely with the reflective and/or the absorbing material, the main surface of the ceramic
- the conversion element which comprises the light-emitting surfaces of the pixel regions, forms a continuous plane.
- reflective material for filling the grooves one of the following materials is suited: a polymer filled with titanium oxide particles, a polymer filled with aluminum oxide
- a polymer filled with YAG particles (YAG for yttrium-aluminum-garnet) , a polymer filled with barium sulphate particles, a polymer filled with yttrium oxide particles, a polymer filled with lutetium oxide particles, a polymer filled with gadolinium oxide particles, a polymer filled with particles of metal aluminates, a polymer filled with particles of metal nitrides, Teflon, a Teflon-based composite, aluminum oxide ceramic, YAG ceramic, titanium oxide ceramic, yttrium oxide ceramic, lutetium oxide ceramic, gadolinium oxide ceramic, metal aluminates, metal nitrides.
- a carbon or a carbon-filled polymer As absorbing material for filling the grooves between the pixel regions a carbon or a carbon-filled polymer is suited. Also, the materials mentioned above for the absorbing layer are suited as absorbing material filling the grooves.
- the grooves are filled with a ceramic
- the grooves can be filled in the green state of the ceramic basic body with a pre-ceramic material such as a slurry of the filling
- the ceramic conversion element can be sintered in one single step.
- phosphor which converts light of the first wavelength range into light of the second wavelength range
- the ceramic conversion element comprises two or more different kinds of phosphors.
- a ceramic conversion element comprises a plurality of pixel regions.
- the pixel regions are separated from each other by grooves.
- direct adjacent pixel regions are separated from each other by one groove.
- the pixel regions are optically isolated from each other.
- the optical isolation of the micro-pixels prevents crosstalk and therefore leads to a higher an improved light confinement into the pixel region of the ceramic conversion element.
- the ceramic conversion element further comprises a connecting part, which connects the pixel regions along a main surface of the conversion element, such that the ceramic conversion element is formed as one single piece. Therefore, the pixel regions are connected to each other by the connecting part.
- the connecting part has a main surface parallel to the main surface comprising the top surfaces of the pixel regions.
- the main surface of the connecting part is intended to be a light exit surface of the ceramic conversion element.
- the top surfaces of the pixel regions are intended to be part of a light exit surface of the ceramic conversion element.
- the light exit surface of the conversion element can be flat or roughened.
- the light exit surface can be formed of a natural ceramic surface.
- the light exit surface of the ceramic conversion element is structured with an array of microlenses or microspheres. The microspheres can be arranged in an ordered or random manner. Further, monolayer or multilayer arrangement of the
- a diameter of the microspheres is preferably between 100 nanometer and 5000 nanometer
- the light exit surface of the ceramic conversion element is structured with a photonic crystal or a pattern with non-periodic order such as a quasicrystal . Also the structuring of the light exit surface of the ceramic conversion element with a pattern according to a deterministic aperiodic nano structure (DANS) is possible.
- a layer with a graded refractive index is deposited, such that a surface of the layer forms the light exit surface of the conversion element.
- the ceramic conversion element is particularly preferably formed of a dense ceramic material, which allows efficient operation at higher temperatures and higher light fluxes than conversion elements formed from a resin, such as silicone, mixed with phosphor particles.
- the ceramic conversion element is formed of a phosphor.
- the pixel regions can have different shapes such as square, circular, triangular, hexagonal or a combination thereof.
- a length of a pixel region is preferably smaller or equal than approximately 500 microns.
- a length of the pixel region is between 50 microns and 500 microns, limits included.
- a length of the pixel region is between 100 microns and 150 microns, limits included.
- a length of the pixel region can be for example a width or a diameter.
- the pixel regions of the ceramic conversion element can be arranged periodic, non-periodic, with uniform pixel sizes or with non-uniform sizes.
- the pixel regions of the ceramic conversion element can be arranged in a periodic manner, for example in a square, a triangular or a hexagonal array. Also non-periodic arrangements can be performed.
- a groove of the ceramic conversion element has sidewalls, which are arranged in front of each other.
- the sidewalls of the groove can be, for example, formed in a vertical manner, in a V-shaped manner or in an inverted V-shaped manner.
- the sidewalls of the groove can be irregularly shaped .
- a depth of the groove lies preferably between 10% to 85% of the total thickness of the ceramic conversion element, limits included.
- the groove has a depth of at least 50% of the thickness of the ceramic conversion element.
- the groove has a depth of at least 70% of the thickness of the ceramic conversion element.
- the width of a groove which means the distance between the sidewalls of the groove, is between 5 microns and 50 microns, limits included.
- the width of the groove is smaller or equal to 15 microns.
- the ceramic conversion element preferably has a total
- the size of a main surface of the ceramic conversion element is preferably between 0.25 mm 2 and 100 mm 2 , limits included. Particularly preferably, the area of the main surface of the conversion element is between 1 mm 2 and 25 mm 2 , limits included .
- the pixelated ceramic conversion element can be used together with a light emitting pixelated semiconductor chip to form an optoelectronic device. As a pixelated light emitting
- a light-emitting diode chip can be used.
- a laser diode chip can be used in order to selectively illuminate the desired pixel regions of the ceramic conversion element.
- the light-emitting chip such as a laser diode chip or a light-emitting diode chip, emits light of a first wavelength range, which is at least partially converted by the ceramic conversion element into light of the second wavelength range.
- the first wavelength range is preferably from the blue or the ultraviolet spectral range.
- the first wavelength range is preferably from the blue or the ultraviolet spectral range.
- wavelength range has a dominant wavelength between 365 nm and 475 nm, limits included.
- the pixelated ceramic conversion element is combined with a similarly structured light-emitting chip, such as a light-emitting diode chip.
- a similarly structured light-emitting chip such as a light-emitting diode chip.
- the light- emitting diode chip has pixel regions, which are formed and arranged in the same way as the pixel regions of the ceramic conversion element.
- the pixel regions of the conversion element and the pixel regions of the light-emitting chip are preferably aligned to each other such that the top surfaces of the pixel regions of the ceramic conversion element and of the pixelated light- emitting chip cover each other.
- the ceramic conversion element and the light-emitting chip can be attached to each other by an adhesive, such as silicone or epoxy resin.
- an adhesive such as silicone or epoxy resin.
- a glass in particular a low-melting glass, is suited to attach the ceramic conversion element and the light-emitting chip to each other.
- the pixel regions of the light-emitting chip and the pixel regions of the ceramic conversion element face each other.
- a main face of the connecting part forms a light exit surface of the optoelectronic device.
- the ceramic conversion element is arranged on the pixelated light-emitting chip such that the connecting element faces the pixel regions of the light-emitting diode.
- the top surfaces of the pixel regions of the conversion element are part of a light exit surface of the optoelectronic device.
- An optoelectronic device as described herein is particularly useful for automotive applications, such as automotive headlamps, projection systems or displays.
- Figures 13 and 14 each shows a schematic sectional view of a ceramic conversion element according to an embodiment.
- Figures 15 and 16 each shows a schematic sectional view of an optoelectronic device according to an embodiment.
- a ceramic basic body 1 in the sintered state is provide in a first step
- the ceramic basic body 1 in the sintered state comprises a phosphor (not shown) , which is suited to convert light of a first wavelength range and to light of a second wavelength range.
- the ceramic basic body 1 in the sintered state is structured by laser structuring ( Figure 2) .
- the laser light is symbolized in Figure 2 by an arrow 2.
- a ceramic conversion element 3 in the sintered state is achieved as shown in Figure 3.
- the ceramic conversion element 3 has a plurality of pixel regions 4, which are connected by a continuously connecting part 5 along a main surface 6 of the connecting part 5.
- the continuously connecting part 5 is formed as a plate in the present case.
- Each pixel region 4 has a square base area.
- the pixel regions 4 are arranged on the continuously connecting part 5 at equidistant distances. Directly adjacent pixel regions 4 are separated from each other by a groove 7.
- the groove 7 has two vertical sidewalls 8, 8', which face each other.
- Figure 4 shows a schematic plan view of the ceramic
- a ceramic basic body 1' is provided in the green state.
- the ceramic basic body 1' in the green state comprises a phosphor (not shown), which is suited to convert light of a first wavelength range and to light of a second wavelength range.
- the ceramic basic body 1' in the green state is structured by laser structuring ( Figure 5) .
- the laser light is again symbolized by an arrow 2.
- laser structuring pixel regions 4 are formed within the ceramic basic body 1' in the green state.
- the pixel regions 4 are arranged on a continuously connecting part 5 in an equidistant manner as already described in connection with Figures 3 and 4.
- the conversion element in the green state of Figure 6 is sintered such that the organic binder is removed from the ceramic conversion element 3 ( Figure 7) .
- the conversion element shrinks by about 15% to 20%.
- a ceramic basic body 1' in the green state is provided in a first step ( Figure 8) .
- the ceramic basic body 1' in the green state is structured by micro-embossing with a stamp 9 or a press such as a plate press, a rotary press ( Figure 9) .
- a stamp 9 or a press such as a plate press, a rotary press
- Figure 11 the stamp 9 is removed from the ceramic basic body 1' in the green state.
- the ceramic basic body 1', individual parts of the structured ceramic basic body 1' in the green state can be singulated for example by punching. Singulation in this context means the separation of the ceramic basic body 1' into smaller pieces.
- the individual parts of the ceramic basic body 1' in the green state can be pre-fired and sintered to remove the binder and other organic constituents and to facilitate densification of the ceramic material.
- the ceramic basic body 1' shrinks ( Figure 12) .
- the period of the micro-array which means the center-to center distance of directly adjacent pixel regions, might be in the range of 100 microns to 150 microns, limits included.
- the distances between two directly adjacent pixel regions 4 are preferably between 5 microns and 15 microns, limits included.
- the pixel regions 4 are separated from each other by grooves 7.
- the depth of each groove 7 is preferably between 10% to 85% of the total thickness of the ceramic conversion element 3. Particularly preferably, the depth of the groove 7 is 85% of the total thickness of the ceramic conversion element 3.
- the total thickness of the conversion element 3 is preferably between 20 microns and 500 microns, limits included and particularly preferably between 100 microns and 200 microns, limits included.
- the total area of a main surface of the ceramic conversion element 3 is
- the ceramic conversion element 3 according to the embodiment of Figure 13 has grooves 7, which are completely filled with an absorbing and/or a reflective material 10 as described in further detail above. According to the
- the grooves 7 are filled completely such that the filling material fits flush with a top surface of the pixel regions 4. In such a way a completely continuous plane is formed.
- the ceramic conversion element 3 according to the embodiment of Figure 14 has pixel regions 4 with sidewalls 8, which are covered with a reflective and/or absorbing layer 11.
- the optoelectronic device according to the embodiment of Figure 15 comprises a pixelated ceramic conversion element 3 as, for example, described with respect to Figures 3, 4, 13 or 14. Further, the optoelectronic device comprises a
- the pixelated light- emitting chip 12 has pixel regions 4', which are shaped in the same way as the pixel regions 4 of the ceramic conversion element 3.
- the pixel regions 4 of the ceramic conversion element 3 and the pixel regions 4' of the pixelated light- emitting chip 12 are aligned to each other in such a way that their top surfaces cover each other.
- the pixel regions 4 of the ceramic conversion element 3 and the pixel regions 4' of the pixelated light-emitting chip 12 face each other. They can be fixed to each other by an adhesive (not shown) .
- the optoelectronic device according to the embodiment of Figure 16 also comprises a pixelated ceramic conversion element 3 as already described in connection with Figures 3, 4, 13 and 14 as well as a pixelated light-emitting chip 12.
- the ceramic conversion element 3 is arranged such that its connecting part 5 faces towards the pixel regions 4 of the pixelated light-emitting chip 12.
- the invention is not limited to the description of the embodiments. Rather, the invention comprises each new feature as well as each combination of features, particularly each combination of features of the claims, even if the feature or the combination of features itself is not explicitly given in the claims or embodiments.
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Abstract
A method for producing a ceramic conversion element comprising the following steps is provided: - providing a ceramic basic body in the green state, said ceramic basic body comprises a phosphor, which converts light of a first wavelength range into light of a second wavelength range, - structuring the ceramic basic body in the green state such that pixel regions are formed within the ceramic basic body, said pixel regions being separated from each other by grooves, while the ceramic basic body comprises a continuously connecting part, which connects the pixel regions along a main surface, wherein - the structuring is performed by one of the following methods: laser structuring, micro-embossing, sawing, grinding, etching in combination with a mask, sand blasting, jet cutting. Alternatively, a ceramic basic body in the sintered state is provided and structured accordingly. Further, a conversion element as well as a optoelectronic device is described.
Description
Description
METHOD FOR PRODUCING A CERAMIC CONVERSION ELEMENT, CERAMIC CONVERSION ELEMENT AND OPTOELECTRONIC DEVICE
The present application is directed to a method for produci a ceramic conversion element, a ceramic conversion element and an optoelectronic device with a ceramic conversion element .
Ceramic conversion elements are, for example, described in WO 2014/090893 Al, US 8, 492, 182 B2 and US 2011/0210658 Al .
Further, WO 2013/164737 Al describes a pixelated chip with a plurality of separated conversion elements, while S. Zhang et al . , CMOS-controlled color-tunable smart display, IEEE
Photonics Journal, vol. 4, no. 5, October 2012, pages 1639 to 1646 describes a color tunable smart display.
It is an object of the present invention to provide a ceramic conversion element for a micro-pixelated light emitting diode (LED), which allows easy handling and alignment. Further, a fabrication method for such a ceramic conversion element as well as an optoelectronic device with such a ceramic
conversion element should be provided.
According to an aspect of a method for producing a ceramic conversion element a ceramic basic body in the green state is provided. The ceramic basic body comprises a phosphor, which converts light of a first wavelength range into light of a second wavelength range. The second wavelength range is different from the first wavelength range and comprises preferably longer wavelengths than the first wavelength range .
A ceramic basic body in the green state can be manufactured as described in the following. First of all, a slurry is produced by mixing ceramic phosphor particles with an organic binder. Then the ceramic basic body is preformed from the slurry by a ceramic-forming method such as tape casting, injection molding, slip casting, dry pressing, isostatic pressing or hot isostatic pressing. The preformed ceramic basic body in the green state has preferably the form of a cuboid or a plate.
According to a further aspect of the invention, the ceramic basic body in the green state is structured such that pixel regions are formed within the ceramic basic body. The pixel regions are separated from each other by grooves, while the ceramic basic body comprises a continuously connecting part, which connects the pixel regions along a main surface of the ceramic basic body. The structuring of the ceramic basic body in the green state can be performed by laser structuring, such as laser
scribing, micro-embossing, mechanical manipulation such as sawing or grinding, etching in combination with a mask, erosion methods such as sandblasting or jet cutting, or gravure rolling and other similar methods. As a sawing method diamond sawing can be used, while as a jet cutting method, water-jet cutting can be used. As a mask a photolithographic mask might be suited. For example, the ceramic basic body in the green state can be pixelated by laser structuring and then be sintered. Since the work piece shrinks when going from the green state to the sintered state, a benefit of this approach is that the
structures can be made approximately 15% to 20% smaller than what is possible by directly scribing in the sintered state. In particular, the width of the grooves between the pixel regions and/or the width of the pixel regions itself can be made approximately 15% to 20% smaller than what is possible by directly scribing in the sintered state
Therefore, laser structuring such as laser scribing is a preferred method for structuring the ceramic basic body into pixel regions in the green state.
According to a further aspect of the invention micro- embossing can be used as a method for structuring the ceramic basic body in the green state. While in the green state, the ceramic basic body is embossed with a stamp that transfers the pattern of the stamp within the ceramic basic body. The embossing can be accomplished in a number of ways such as with a hot press, a stamp or a roller, for example a nip or a gravure .
Laser structuring has the advantage over hot embossing for structuring the ceramic basic body that the handling is easier. Further, the yield is better when using laser
structuring for the structuring step in comparison to other methods. Over photolithographic methods and micro-embossing methods laser structuring has further cost advantages. In particular, the stamps required for hot embossing can be difficult in production and therefore quite expensive. Also, laser structuring offers easy access to alternative
pixilation patterns with complex designs such as irregular shapes or aperiodic arrangements. In contrast to hot
embossing, which requires a new stamp for every new pattern
of pixel regions, laser structuring of different patterns can be performed with the same tool.
A further method for structuring the ceramic basic body in the green state is gravure rolling. Gravure rolling has the advantage over hot embossing with a stamp that the green tape is easier released.
According to a further aspect of the invention, the ceramic basic body is sintered after the structuring. If the ceramic basic body in the green state is sintered, it shrinks by approximately 15% to 20%.
Regarding the method explained above, the ceramic basic body is in the green state when structured. Alternatively, it is also possible that a ceramic basic body is already provided in a sintered state and then structured. Hot-embossing is not suited to structure the ceramic basic body in the sintered state. The ceramic basic body in the sintered state also has preferably the form of a cuboid or a plate.
The ceramic basic body in the sintered state comprises a phosphor, which converts light of a first wavelength range into light of a second wavelength range. Particularly
preferably, the ceramic basic body consists of the phosphor.
The sintered ceramic basic body is structured such that pixel regions are formed within the sintered ceramic basic body. The pixel regions are separated from each other by grooves, while the sintered ceramic basic body further comprises a continuously connecting part, which connects the pixel regions along a main surface of the sintered basic body.
According to an aspect of the invention, the sintered ceramic basic body can be structured by laser structuring, mechanical manipulation such as sawing or grinding, or erosion methods such as sand-blasting or jet cutting. As a sawing method diamond sawing can be used, while as a jet cutting method, water-jet cutting can be used.
According to the methods described above, a basic ceramic body in the green state or in the sintered state is provided in a first step and then structured. Alternatively, it is also possible to directly form a structured ceramic body in the green state from the slurry, for example by printing or injection molding. The printing can be performed directly or with the help of a template. When using injection molding to directly form a structured ceramic conversion element from the slurry, the mold has the desired structure of the
conversion element. After directly manufacturing of the structured ceramic conversion element in the green state from the slurry, the structured ceramic conversion element in the green state is sintered. During the sintering step the ceramic conversion element and in particular the structure of the conversion element shrinks by approximately 15% to 20%, limits included. According to a further aspect of the invention sidewalls of the pixel regions are coated with a reflective and/or
absorbing material. Preferably, the reflective and/or an absorbing material forms a reflective and/or absorbing layer on the sidewalls.
Preferably, the sidewalls are coated with a mixture of an absorbing material and a reflective material. For example, the absorbing material of the mixture absorbs electromagnetic
radiation in the blue spectral range and the reflecting material of the mixture reflects electromagnetic radiation in the yellow spectral range or vice versa. The reflective and/or absorbing layer can be deposited by one of the following methods: evaporation, pulsed laser
deposition, pulsed electron deposition, sputtering, chemical vapour deposition, electron beam deposition, electroplating, electrodeposition, electroless deposition, sedimentation. Preferably, the coating of the sidewalls of the pixel regions is performed in the sintered state of the ceramic conversion element. As a reflective material for the layer, a metal such as silver or aluminum can be used. As absorbing material a carbon filled polymer or a wavelength selective absorber can be used. A carbon filled polymer is typically suited to absorb electromagnetic radiation of a broad range of visible wavelengths. A wavelength selective absorber is preferably suited to absorb electromagnetic radiation of the blue spectral range and to transmit
electromagnetic radiation of the yellow spectral range.
Alternatively, the wavelength selective absorber is
preferably suited to absorb electromagnetic radiation of the yellow spectral range and to transmit or to reflect
electromagnetic radiation of the blue spectral range. In particular, the wavelength selective absorber absorbs only electromagnetic radiation of the blue spectral range or electromagnetic radiation of the yellow spectral range. This helps to prevent cross-talk between neighboured pixel
regions.
Further, a polymer filled with an absorbing substance, such as carbon black or a pigment, can be used as absorbing
material. Also the following materials are suited to be used as absorbing material: nano-structured carbon, silicon, a metal, a non-metal. For example, the top surfaces of the pixel regions of the conversion element are covered during the deposition of the reflective and/or absorbing layer, for example with a mask. In such a way the top surfaces, which might be intended to be light-exit surfaces of the finished ceramic conversion element, are free from the reflective or absorbing material of the layer with advantage.
Alternatively, the top surfaces of the pixel regions, which are intended to be light exit surfaces, can be cleaned after the deposition of the reflective and/or absorbing layer, for example by grinding and/or polishing.
Additionally or alternatively to a coating of the sidewalls of the pixel regions with a reflective and/or absorbing layer, the grooves between the pixel regions can be filled with a reflective and/or absorbing material. Preferably, the grooves are filled completely with the reflective and/or absorbing material, such that it is arranged in a flush manner with the top surfaces of the pixel regions. If the grooves are filled completely with the reflective and/or the absorbing material, the main surface of the ceramic
conversion element, which comprises the light-emitting surfaces of the pixel regions, forms a continuous plane. As reflective material for filling the grooves one of the following materials is suited: a polymer filled with titanium oxide particles, a polymer filled with aluminum oxide
particles, a polymer filled with YAG particles (YAG for
yttrium-aluminum-garnet) , a polymer filled with barium sulphate particles, a polymer filled with yttrium oxide particles, a polymer filled with lutetium oxide particles, a polymer filled with gadolinium oxide particles, a polymer filled with particles of metal aluminates, a polymer filled with particles of metal nitrides, Teflon, a Teflon-based composite, aluminum oxide ceramic, YAG ceramic, titanium oxide ceramic, yttrium oxide ceramic, lutetium oxide ceramic, gadolinium oxide ceramic, metal aluminates, metal nitrides.
As absorbing material for filling the grooves between the pixel regions a carbon or a carbon-filled polymer is suited. Also, the materials mentioned above for the absorbing layer are suited as absorbing material filling the grooves.
If the grooves are filled with a ceramic, the grooves can be filled in the green state of the ceramic basic body with a pre-ceramic material such as a slurry of the filling
material. Then the ceramic conversion element can be sintered in one single step.
As phosphor, which converts light of the first wavelength range into light of the second wavelength range, one of the following materials is suited: (REi_xCex) 3AI5O12, wherein RE=Y, Lu, Tb, Gd, individually or in combination; 0<x<=0.1,
(RE!_xCex) 3Al5-2yMgySiyOi2-y, wherein RE=Y, Lu, Tb, Gd,
individually and/or in any combinations; 0<x<=0.1; 0<=y<=0.5, (RE!_xCex) 3Al5-ySiyOi2-y y, wherein RE=Y, Lu, Tb, Gd,
individually and/or in any combinations; 0<x<=0.1; 0<=y<=0.5, (AEi_xEux) 2S15 8, wherein AE=Ca, Sr, Ba, individually and/or in any combinations; 0<x<=0.1, (AEi_xEux) AIS1N3, wherein AE=Ca, Sr, Ba, individually and/or in any combinations; 0<x<=0.1, (AEi_xEux) 3Ga3 5, wherein AE=Ca, Sr, Ba, individually and/or in
any combinations; 0<x<=0.1, (AEi_xEux) S12O2 2, wherein AE=Ca, Sr, Ba, individually and/or in any combinations; 0<x<=0.1, (AExEuy) Sii2-2x-3yAl2x+3yOyN16-y, wherein AE=Ca, Sr, Ba,
individually and/or in any combinations; 0.2<=x<=2.2;
0<y<=0.1, (AEi-xEux) 2S1O4, wherein AE=Ca, Sr, Ba, individually and/or in any combinations; 0<x<=0.1, (AEi_xEux) 3S1O5, wherein AE=Ca, Sr, Ba, individually and/or in any combinations;
0<x<=0.1. It is also possible that the ceramic conversion element comprises two or more different kinds of phosphors.
A ceramic conversion element according to an aspect of the invention comprises a plurality of pixel regions. The pixel regions are separated from each other by grooves. In
particular, direct adjacent pixel regions are separated from each other by one groove. With the help of the grooves the pixel regions are optically isolated from each other. The optical isolation of the micro-pixels prevents crosstalk and therefore leads to a higher an improved light confinement into the pixel region of the ceramic conversion element.
According to a further aspect of the invention the ceramic conversion element further comprises a connecting part, which connects the pixel regions along a main surface of the conversion element, such that the ceramic conversion element is formed as one single piece. Therefore, the pixel regions are connected to each other by the connecting part. The connecting part has a main surface parallel to the main surface comprising the top surfaces of the pixel regions.
According to an aspect of the invention, the main surface of the connecting part is intended to be a light exit surface of
the ceramic conversion element. Alternatively, the top surfaces of the pixel regions are intended to be part of a light exit surface of the ceramic conversion element. The light exit surface of the conversion element can be flat or roughened. The light exit surface can be formed of a natural ceramic surface. Further, it is also possible that the light exit surface of the ceramic conversion element is structured with an array of microlenses or microspheres. The microspheres can be arranged in an ordered or random manner. Further, monolayer or multilayer arrangement of the
microspheres are possible. A diameter of the microspheres is preferably between 100 nanometer and 5000 nanometer,
particularly preferably between 200 nanometer and 1000 nanometer.
According to a further embodiment of the invention, the light exit surface of the ceramic conversion element is structured with a photonic crystal or a pattern with non-periodic order such as a quasicrystal . Also the structuring of the light exit surface of the ceramic conversion element with a pattern according to a deterministic aperiodic nano structure (DANS) is possible. According to a further embodiment of the ceramic conversion element, on the main surface of the connecting part or on the top surfaces of the pixel regions a layer with a graded refractive index is deposited, such that a surface of the layer forms the light exit surface of the conversion element.
Since the pixels are connected to each other, easy alignment of the pixelated ceramic conversions element with a pixelated semiconductor body can be achieved. In particular, the
alignment of the ceramic conversion element has only to be performed once and not separately for each pixel region as in the case of arrangement of separate conversion elements on every pixel region. Further, the handling of the ceramic conversion element, which comprises a plurality of pixel regions, can be performed with known and reliable equipment and is much easier than handling very small single conversion elements for each pixel. The ceramic conversion element is particularly preferably formed of a dense ceramic material, which allows efficient operation at higher temperatures and higher light fluxes than conversion elements formed from a resin, such as silicone, mixed with phosphor particles. Particularly preferably, the ceramic conversion element is formed of a phosphor.
The pixel regions can have different shapes such as square, circular, triangular, hexagonal or a combination thereof. A length of a pixel region is preferably smaller or equal than approximately 500 microns. For example, a length of the pixel region is between 50 microns and 500 microns, limits included. Preferably, a length of the pixel region is between 100 microns and 150 microns, limits included. A length of the pixel region can be for example a width or a diameter.
The pixel regions of the ceramic conversion element can be arranged periodic, non-periodic, with uniform pixel sizes or with non-uniform sizes.
The pixel regions of the ceramic conversion element can be arranged in a periodic manner, for example in a square, a
triangular or a hexagonal array. Also non-periodic arrangements can be performed.
A groove of the ceramic conversion element has sidewalls, which are arranged in front of each other. The sidewalls of the groove can be, for example, formed in a vertical manner, in a V-shaped manner or in an inverted V-shaped manner.
Furthermore, the sidewalls of the groove can be irregularly shaped .
A depth of the groove lies preferably between 10% to 85% of the total thickness of the ceramic conversion element, limits included. Preferably, the groove has a depth of at least 50% of the thickness of the ceramic conversion element.
Particularly preferably, the groove has a depth of at least 70% of the thickness of the ceramic conversion element.
Preferably, the width of a groove, which means the distance between the sidewalls of the groove, is between 5 microns and 50 microns, limits included. Preferably, the width of the groove is smaller or equal to 15 microns.
The ceramic conversion element preferably has a total
thickness of between 20 microns and 500 microns, limits included.
The size of a main surface of the ceramic conversion element is preferably between 0.25 mm2 and 100 mm2, limits included. Particularly preferably, the area of the main surface of the conversion element is between 1 mm2 and 25 mm2, limits included .
The pixelated ceramic conversion element can be used together with a light emitting pixelated semiconductor chip to form an optoelectronic device. As a pixelated light emitting
semiconductor chip a light-emitting diode chip can be used. Alternatively, a laser diode chip can be used in order to selectively illuminate the desired pixel regions of the ceramic conversion element.
The light-emitting chip, such as a laser diode chip or a light-emitting diode chip, emits light of a first wavelength range, which is at least partially converted by the ceramic conversion element into light of the second wavelength range.
The first wavelength range is preferably from the blue or the ultraviolet spectral range. In particular, the first
wavelength range has a dominant wavelength between 365 nm and 475 nm, limits included.
Preferably, the pixelated ceramic conversion element is combined with a similarly structured light-emitting chip, such as a light-emitting diode chip. Preferably, the light- emitting diode chip has pixel regions, which are formed and arranged in the same way as the pixel regions of the ceramic conversion element.
The pixel regions of the conversion element and the pixel regions of the light-emitting chip are preferably aligned to each other such that the top surfaces of the pixel regions of the ceramic conversion element and of the pixelated light- emitting chip cover each other.
The ceramic conversion element and the light-emitting chip can be attached to each other by an adhesive, such as
silicone or epoxy resin. Further, a glass, in particular a low-melting glass, is suited to attach the ceramic conversion element and the light-emitting chip to each other. According to an aspect of the optoelectronic device the pixel regions of the light-emitting chip and the pixel regions of the ceramic conversion element face each other. In this case, a main face of the connecting part forms a light exit surface of the optoelectronic device.
Alternatively, it is possible that the ceramic conversion element is arranged on the pixelated light-emitting chip such that the connecting element faces the pixel regions of the light-emitting diode. In this case, the top surfaces of the pixel regions of the conversion element are part of a light exit surface of the optoelectronic device.
An optoelectronic device as described herein is particularly useful for automotive applications, such as automotive headlamps, projection systems or displays.
Further preferred embodiments and developments of the
invention are described in the following in connection with the Figures.
In connection with the schematic views of Figures 1 to 4 a first embodiment of a method is described.
In connection with the schematic views of Figures 5 to 7 a second embodiment of a method is described.
In connection with the schematic views of Figures 8 to 12 a further embodiment of a method is described.
Figures 13 and 14 each shows a schematic sectional view of a ceramic conversion element according to an embodiment. Figures 15 and 16 each shows a schematic sectional view of an optoelectronic device according to an embodiment.
Equal or similar elements as well as elements of equal function are designated with the same reference signs in the figures. The figures and the proportions of the elements shown in the figures are not regarded as being shown to scale. Rather, single elements, in particular layers, can be shown exaggerated in magnitude for the sake of better presentation .
According to the method of Figures 1 to 4, a ceramic basic body 1 in the sintered state is provide in a first step
(Figure 1) . The ceramic basic body 1 in the sintered state comprises a phosphor (not shown) , which is suited to convert light of a first wavelength range and to light of a second wavelength range.
In a next step the ceramic basic body 1 in the sintered state is structured by laser structuring (Figure 2) . The laser light is symbolized in Figure 2 by an arrow 2. With the help of laser structuring a ceramic conversion element 3 in the sintered state is achieved as shown in Figure 3.
The ceramic conversion element 3 has a plurality of pixel regions 4, which are connected by a continuously connecting part 5 along a main surface 6 of the connecting part 5. The continuously connecting part 5 is formed as a plate in the present case. Each pixel region 4 has a square base area.
Further, the pixel regions 4 are arranged on the continuously connecting part 5 at equidistant distances. Directly adjacent pixel regions 4 are separated from each other by a groove 7. The groove 7 has two vertical sidewalls 8, 8', which face each other.
Figure 4 shows a schematic plan view of the ceramic
conversion element 3 according to Figure 3. It can be seen that the pixel regions 4 are arranged in a regular pattern having columns and rows.
According to the method of Figures 5 to 7 a ceramic basic body 1' is provided in the green state. The ceramic basic body 1' in the green state comprises a phosphor (not shown), which is suited to convert light of a first wavelength range and to light of a second wavelength range.
In a next step the ceramic basic body 1' in the green state is structured by laser structuring (Figure 5) . The laser light is again symbolized by an arrow 2. By laser structuring pixel regions 4 are formed within the ceramic basic body 1' in the green state. The pixel regions 4 are arranged on a continuously connecting part 5 in an equidistant manner as already described in connection with Figures 3 and 4.
In a next step the conversion element in the green state of Figure 6 is sintered such that the organic binder is removed from the ceramic conversion element 3 (Figure 7) . During the sintering process the conversion element shrinks by about 15% to 20%.
According to the embodiment of Figures 8 to 12 a ceramic basic body 1' in the green state is provided in a first step
(Figure 8) . Then the ceramic basic body 1' in the green state is structured by micro-embossing with a stamp 9 or a press such as a plate press, a rotary press (Figure 9) . By pressing the stamp 9 within the ceramic basic body 1' in the green state, the pattern of the stamp 9 is transferred to the ceramic basic body 1' in the green state (Figure 10) . Then, the stamp 9 is removed from the ceramic basic body 1' in the green state (Figure 11) .
Once the pattern of the stamp 9 has been pressed into the ceramic basic body 1' in the green state in order to
structure the ceramic basic body 1', individual parts of the structured ceramic basic body 1' in the green state can be singulated for example by punching. Singulation in this context means the separation of the ceramic basic body 1' into smaller pieces.
Afterwards, the individual parts of the ceramic basic body 1' in the green state can be pre-fired and sintered to remove the binder and other organic constituents and to facilitate densification of the ceramic material. During the sintering step, the ceramic basic body 1' shrinks (Figure 12) . The period of the micro-array, which means the center-to center distance of directly adjacent pixel regions, might be in the range of 100 microns to 150 microns, limits included.
The distances between two directly adjacent pixel regions 4 are preferably between 5 microns and 15 microns, limits included. The pixel regions 4 are separated from each other by grooves 7. The depth of each groove 7 is preferably between 10% to 85% of the total thickness of the ceramic
conversion element 3. Particularly preferably, the depth of the groove 7 is 85% of the total thickness of the ceramic conversion element 3. The total thickness of the conversion element 3 is preferably between 20 microns and 500 microns, limits included and particularly preferably between 100 microns and 200 microns, limits included. The total area of a main surface of the ceramic conversion element 3 is
preferably between 1 mm2 and 100 mm2, limits included. In contrast to the ceramic conversion element 3 of Figures 3 and 4, the ceramic conversion element 3 according to the embodiment of Figure 13 has grooves 7, which are completely filled with an absorbing and/or a reflective material 10 as described in further detail above. According to the
embodiment of Figure 13, the grooves 7 are filled completely such that the filling material fits flush with a top surface of the pixel regions 4. In such a way a completely continuous plane is formed. In contrast to the ceramic conversion element 3 of Figures 3 and 4, the ceramic conversion element 3 according to the embodiment of Figure 14 has pixel regions 4 with sidewalls 8, which are covered with a reflective and/or absorbing layer 11.
The optoelectronic device according to the embodiment of Figure 15 comprises a pixelated ceramic conversion element 3 as, for example, described with respect to Figures 3, 4, 13 or 14. Further, the optoelectronic device comprises a
pixelated light-emitting chip 12. The pixelated light- emitting chip 12 has pixel regions 4', which are shaped in the same way as the pixel regions 4 of the ceramic conversion element 3. The pixel regions 4 of the ceramic conversion
element 3 and the pixel regions 4' of the pixelated light- emitting chip 12 are aligned to each other in such a way that their top surfaces cover each other. Furthermore, the pixel regions 4 of the ceramic conversion element 3 and the pixel regions 4' of the pixelated light-emitting chip 12 face each other. They can be fixed to each other by an adhesive (not shown) .
The optoelectronic device according to the embodiment of Figure 16 also comprises a pixelated ceramic conversion element 3 as already described in connection with Figures 3, 4, 13 and 14 as well as a pixelated light-emitting chip 12. In contrast to the optoelectronic device of Figure 10, the ceramic conversion element 3 is arranged such that its connecting part 5 faces towards the pixel regions 4 of the pixelated light-emitting chip 12.
The invention is not limited to the description of the embodiments. Rather, the invention comprises each new feature as well as each combination of features, particularly each combination of features of the claims, even if the feature or the combination of features itself is not explicitly given in the claims or embodiments.
Claims
1. Method for producing a ceramic conversion element
comprising the steps:
- providing a ceramic basic body in the green state, said ceramic basic body comprises a phosphor, which converts light of a first wavelength range into light of a second wavelength range,
- structuring the ceramic basic body in the green state such that pixel regions are formed within the ceramic basic body, said pixel regions being separated from each other by
grooves, while the ceramic basic body comprises a
continuously connecting part, which connects the pixel regions along a main surface, wherein
- the structuring is performed by one of the following methods: laser structuring, micro-embossing, sawing,
grinding, etching in combination with a mask, sand blasting, jet cutting and gravure rolling.
2. The method of claim 1, wherein the ceramic basic body is sintered after the structuring.
3. The method claim 2, wherein sidewalls of the pixel regions are coated with a reflective and/or an absorbing layer.
4. The method of claim 3, wherein the reflective and/or absorbing layer is deposited on the sidewalls by one of the following methods: evaporation, pulsed laser deposition, pulsed electron deposition, sputtering, chemical vapour deposition, electron beam deposition, electroplating, electrodeposition, electroless deposition, sedimentation.
5. The method of claim 3, wherein top-surfaces of the pixel regions are covered during the deposition of the reflective and/or absorbing layer.
6. The method of claim 3, wherein the top-surfaces of the pixel regions are cleaned after the deposition of the
reflective and/or absorbing layer by grinding and/or
polishing .
7. The method of claim 2, wherein the grooves are filled with a reflective material and/or an absorbing material.
8. The method of claim 7, wherein the reflective material is chosen from the following group: a polymer filled with titanium oxide particles, a polymer filled with aluminum oxide particles, a polymer filled with YAG-particles , a polymer filled with barium sulfate particles, teflon, a teflon-based composite, aluminum oxide ceramic, YAG-ceramic, titanium oxide ceramic.
9. The method of claim 7, wherein the absorbing material is a carbon or a carbon-filled polymer.
10. The method of claim 1, wherein the grooves are filled with a reflective and/or absorbing slurry and the ceramic basic body is sintered after filling the grooves.
11. Method for producing a ceramic conversion element
comprising the steps:
- providing a sintered ceramic basic body, said sintered ceramic basic body comprises a phosphor, which converts light of a first wavelength range into light of a second wavelength range,
- structuring the sintered basic body such that pixel regions are formed within the sintered ceramic basic body, said pixel regions being separated from each other by grooves, while the sintered ceramic basic body comprises a continuously
connecting part, which connects the pixel regions along a main surface, wherein
- the structuring is performed by one of the following methods: laser structuring, sawing, grinding, sand blasting, jet cutting.
12. The method of claim 11, wherein sidewalls of the pixel regions are coated with a reflective and/ or absorbing layer.
13. The method of claim 12, wherein the reflective and/or absorbing layer is deposited on the sidewalls by one of the following methods: evaporation, pulsed laser deposition, pulsed electron deposition, sputtering, chemical vapour deposition, electron beam deposition, electroplating,
electrodeposition, electroless deposition, sedimentation.
14. The method of claim 12, wherein top-surfaces of the pixel regions are covered during the deposition of the reflective and/or absorbing layer.
15. The method of claim 12, wherein the top-surfaces of the pixel regions are cleaned after the deposition of the
reflective and/or absorbing layer by grinding and/or
polishing .
16. The method of claim 11, wherein the grooves are filled with a reflective material and/or absorbing material.
17. The method of claim 16, wherein the absorbing material is a carbon or a carbon-filled polymer.
18. A ceramic conversion element, comprising:
- a plurality of pixel regions, said pixel regions being separated by each other by grooves, and
- a connecting part, which connects the pixel regions along a main surface, such that the ceramic conversion element is formed as one single piece,
- said ceramic conversion element comprising a phosphor, which converts light of a first wavelength range into light of a second wavelength range.
19. The ceramic conversion element of claim 18, wherein the grooves are filled with a reflective and/or absorbing
material .
20. The ceramic conversion element of claim 18, wherein the sidewalls of the pixel-regions are covered with a reflective and/or absorbing layer.
21. The ceramic conversion element of claim 18, wherein a light exit surface of the ceramic conversion element is formed by a main surface of the connecting part or top surfaces of the pixel regions are part of a light exit surface of the ceramic conversion element.
22. The ceramic conversion element of claim 21, wherein the light exit surface is structured with one of the following structures: an array of microlenses, an array of
microspheres, an array of ordered microspheres, an array of randomly arranged microspheres, an array of a monolayer of microspheres, an array of multilayers of microspheres, a
photonic crystal, a surface structure with non-periodic order, quasicrystals , a deterministic aperiodic nano
structure pattern.
23. The ceramic conversion element of claim 21, wherein the light exit surface is formed by a layer with a graded
refractive index.
24. An optoelectronic device with a light emitting pixelated semiconductor chip and a ceramic conversion element according to claim 23.
25. The optoelectronic device according to claim 24, wherein the light emitting pixelated semiconductor chip has pixel regions, which are formed and arranged in the same way as the pixel regions of the ceramic conversion element.
26. The optoelectronic device of claim 24, wherein a main face of the connecting part forms a light exit surface of the optoelectronic device.
27. The optoelectronic device of claim 24, wherein main faces of the pixel regions of the conversion element are part of the light exit surface of the optoelectronic device.
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Cited By (3)
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WO2019025208A1 (en) * | 2017-08-02 | 2019-02-07 | Osram Opto Semiconductors Gmbh | Optoelectronic component and method for producing an optoelectronic component |
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