CONVERSION ELEMENTS COMPRISING AN INFILTRATION MATRIX

Abstract

The invention relates to a conversion element comprising a wavelength-converting conversion material, a matrix material in which the conversion material is inserted, and a substrate on which the matrix material and the conversion material are directly arranged, the matrix material comprising at least one condensed sol-gel material selected from the following group: water glass, metal phosphate, aluminium phosphate, monoaluminium phosphate, modified monoaluminium phosphate, alkoxytetramethoxysilane, tetraethyl orthosilicate, methyltrimethoxysilane, methyltriethoxysilane, titanium alkoxide, silica sol, metal alkoxide, metal oxane or metal alkoxane, the conversion element being arranged in the beam path of a laser source, the conversion element being mounted in a mechanically immobile manner in relation to the laser source, and the radiation of the laser source being dynamically arranged in relation to the conversion element.

Claims

1. A conversion element comprising: at least one matrix including at least one infiltration matrix, 10 to 50 vol % of at least one phosphor, optionally at least one additive, wherein the conversion element has a porosity of 0 to 20 vol %.

2. The conversion element according to claim 1, wherein the at least one matrix is selected from the group consisting of condensed water glass, condensed monoaluminum phosphate, condensed metal phosphate, and combinations thereof.

3. The conversion element according to claim 1, wherein the at least one infiltration matrix is selected from ZrO.sub.2, TiO.sub.2, Al.sub.2O.sub.3, SiO.sub.2, Y.sub.2O.sub.3, HfO.sub.2 and combinations thereof.

4. The conversion element according to claim 1, wherein the at least one phosphor is selected from the group consisting of (Y,Gd,Tb,Lu).sub.3(Al,Ga).sub.5O.sub.12:Ce.sup.3+, (Sr,Ca)AlSiN.sub.3: Eu.sup.2+, (Sr,Ba,Ca,Mg).sub.2Si.sub.5N.sub.8:Eu.sup.2+, (Ca, Sr,Ba).sub.2SiO.sub.4:Eu.sup.2+, α-SiAlON:Eu.sup.2+, β-SiAlON:Eu.sup.2+, (Sr,Ca)S :Eu.sup.2+, (Sr,Ba,Ca).sub.2(Si,Al).sub.5N,O).sub.8:Eu.sup.2+, (Ca, Sr).sub.8Mg(SiO.sub.4).sub.4Cl.sub.2:Eu.sup.2+, (Sr,Ba)Si.sub.2N.sub.2O.sub.2:Eu.sup.2+, perovskites, CdSe, InP and ZnSe.

5. The conversion element according to one of the preceding claim 1, wherein the at least one additive is selected from nanoparticles, scattering particles, nanoplatelets, curing agents, filler particles and catalysts.

6. A process of producing a conversion element comprising the following steps: providing at least one matrix material, adding at least one phosphor to the matrix material, optionally adding at least one curing agent to the phosphor-matrix material mixture, applying the phosphor and matrix material mixture and the curing agent optionally present to a substrate, applying at least one infiltration material to the phosphor matrix material mixture and the optionally present curing agent to form a pre-conversion element, heating and/or drying the pre-conversion element.

7. The process according to claim 6, wherein the at least one matrix material is selected from the group consisting of solutions comprising water glass, monoaluminum phosphate, metal phosphate and mixtures thereof, which are condensed in a subsequent step.

8. The process according to claim 6, wherein the at least one infiltration material is selected from the group consisting of solutions with tetraethyl orthosilicate (TEOS), tetramethyl orthosilicate (TMOS), triethoxymethylsilane (MeTEOS), trimethoxymethylsilane (MeTMOS), polysilazane, silicone, polysiloxane and precursors thereof, water glass, monoaluminum phosphate, metal phosphate and mixtures thereof, which are crosslinked in a subsequent step.

9. The process according to claim 6, wherein the at least one phosphor is selected from the group consisting of (Y,Gd,Tb,Lu).sub.3(Al,Ga).sub.5O.sub.12:Ce.sup.3+, (Sr,Ca)AlSiN.sub.3:Eu.sup.2+, (Sr,Ba,Ca,Mg).sub.2Si.sub.5N.sub.8:Eu.sup.2+, (Ca,Sr,Ba).sub.2SiO.sub.4:Eu.sup.2+, α-SiAlON:Eu.sup.2+, β-SiAlON:Eu.sup.2+, (Sr,Ca)S:Eu.sup.2+, (Sr,Ba,Ca).sub.2(Si,Al).sub.5N,O).sub.8:Eu.sup.2+, (Ca,Sr).sub.8Mg(SiO.sub.4).sub.4Cl.sub.2:Eu.sup.2+, (Sr,Ba)Si.sub.2N.sub.2O.sub.2:Eu.sup.2+, perovskites, CdSe, InP and ZnSe.

10. The process according to claim 9, further comprising the step of: adding at least one additive to the phosphor—matrix material mixture.

11. The process according to claim 10, wherein the at least one additive is selected from the group consisting of nanoparticles, catalysts, scattering particles, nanoplatelets, curing agents and filler particles.

12. The process according to claim 6, wherein heating is to a temperature in the range of 50° C. to 500° C.

13. The conversion element produced according to one of the claim 6.

14. A semiconductor optoelectronic device comprising at least one conversion element according to claim 1.

15. A conversion element comprising: at least one matrix including at least one infiltration matrix, wherein the infiltration matrix infiltrates into the pores of the matrix forming its own matrix in the pores of the matrix, 10 to 50 vol % of at least one phosphor, optionally at least one additive, wherein the conversion element has a porosity of 0 to 20 vol %.

Description

[0150] Figures

[0151] Identical elements, elements of the same kind or elements having the same effect are denoted by the same reference numbers in the figures. The figures and the proportions of the elements shown in the figures with respect to each another are not to be regarded as to scale. Individual elements, especially layer thicknesses, may rather be shown in an exaggerated large manner for better representability and/or understanding.

[0152] FIG. 1 shows a conversion element A without infiltration matrix and a conversion element B according to the invention including infiltration matrix.

[0153] FIG. 2 shows an SEM image of a porous silicate matrix

[0154] FIG. 3 shows an SEM image of a conversion element according to the invention including infiltration matrix

[0155] FIG. 4 shows comparative microscope images of conversion elements after sawing. On the left side, a conversion element without infiltration matrix is shown, and on the right side, a conversion element according to the invention including infiltration matrix is shown.

[0156] FIGS. 5a, 5b show SEM images (micrographs) of a porous matrix after bonding to a chip and glob topping with TiO.sub.2-filled silicone.

[0157] FIGS. 6a, 6b show an SEM image (micrograph) (FIG. 6a) and a cutout thereof (FIG. 6b) of a conversion element according to the invention including infiltration matrix and substrate after bonding to a chip and glob topping with TiO.sub.2-filled silicone.

[0158] FIG. 7 shows a SEM image of a porous matrix following a moisture test in a “pressure cooker”

[0159] FIG. 8 shows a SEM image of a conversion element according to the invention including infiltration matrix prior to the moisture test in the “pressure cooker”

[0160] FIG. 9 shows a SEM image of a conversion element according to the invention including infiltration matrix following the moisture test in the “pressure cooker”

[0161] FIG. 10 shows a cutout of FIG. 9 in higher magnification

[0162] FIG. 11 shows an SEM image of the porous matrix in cross-section

[0163] FIG. 12 shows an SEM image of a conversion element according to the invention including infiltration matrix in cross-section

[0164] FIG. 13 shows the performance of a porous matrix after bonding to a chip and glob topping with TiO.sub.2-filled silicone in an aging test.

[0165] FIG. 14 shows the performance of the conversion element according to the invention including infiltration matrix after bonding to a chip and glob topping with TiO.sub.2-filled silicone in the aging test.

[0166] FIG. 1 shows a conversion element 1 in panel A. The conversion element 1 comprises a matrix 2, phosphors 3 and a substrate 4. Panel B shows a conversion element 1 according to the invention comprising a matrix 2, phosphors 3, a substrate 4 and an infiltration matrix 5. The infiltration matrix 5 penetrates into and fills the pores of the matrix 2. The substrate 4 may optionally be present.

[0167] FIG. 2 shows an SEM image of a matrix 2 after grinding. The composition and production of the conversion element KE1 will be described in the following examples.

[0168] FIG. 3 shows an SEM image of a matrix 2 including an infiltration matrix 5. The composition and production of the conversion element KE3 will be described in the examples below.

[0169] FIG. 4 shows microscope images of conversion elements 1 after sawing in comparison. On the left side, a conversion element including porous matrix 2 is shown and on the right a conversion element according to the invention including infiltration matrix 5 is shown. Herein, it may be seen that the conversion element 1 according to the invention including infiltration matrix 5 behaves more advantageously when performing sawing and is less prone to chipping at the edges. An intact edge is important both for good radiation characteristics and for glob topping with TiO.sub.2-filled silicone. The size of the conversion elements shown is approximately 1 mm×1 mm.

[0170] FIGS. 5a and 5b show SEM images (transverse section) of a porous matrix 2 (with substrate 4 (glass substrate is not shown in the image)) after bonding to a chip 9 and glob topping 6 with TiO.sub.2-filled silicone. Due to the porosity and thus also more uneven surface, a lot of adhesive 7 (silicone in this case) is required for bonding to the chip 9, making the adhesive layer very thick. As a result, the distance from the conversion element 1 to the chip surface increases accordingly resulting in the so-called TiO.sub.2 underflow 8, as may be seen in FIG. 5a. In FIG. 5b strong converter breakouts are visible resulting from lower mechanical stability caused by the pores. The composition and production of the conversion element KE1 will be described in the following examples.

[0171] FIGS. 6a and 6b show an SEM image (cross sectional micrographs) (FIG. 6a) and a cutout (FIG. 6b) thereof of the conversion element 1 according to the invention including infiltration matrix 5 and substrate 4 after bonding to a chip 9 and glob topping 6 with TiO.sub.2-filled silicone. The composition and production of the conversion element KE3 will be described in the following examples. It may be seen from the cross sectional micrograph that there is almost no porosity left in the conversion element 1 and that the infiltration matrix 5 has sufficiently been wetted and bonded. The lower porosity prevents TiO.sub.2-filled silicone from being drawn through the pores into the conversion element 1 and into the adhesive layer 7 (so called TiO.sub.2 underflow 8).

[0172] FIG. 7 shows a SEM image of a porous matrix 2 after a humidity test in the “pressure cooker”. Herein, the conversion element 1 was aged in a closed system at 121° C. and 100% rel. humidity for 288h. The strong crystal growth indicates some corrosion. The composition and production of conversion element KE1 will be described in the examples below.

[0173] FIG. 8 shows an SEM image of a conversion element 1 according to the invention including infiltration matrix 5 before the humidity test in the “pressure cooker” as a comparison with FIG. 9. The composition as well as the production of the conversion element KE3 will be described in the following examples.

[0174] FIG. 9 shows a SEM image of a conversion element 1 according to the invention including infiltration matrix 5 (FIG. 8) after the moisture test in the “pressure cooker” at 121° C. and 100% relative humidity for 288 hours. In comparison with FIG. 7, virtually no difference will be revealed indicating good moisture resistance.

[0175] FIG. 10 shows a cutout of FIG. 9 at 30× higher magnification. On the surface, not more than weak crystal growth is visible, although the magnification is 3× as high as that of FIG. 7. This demonstrates the improved moisture resistance of the conversion element 1 including infiltration matrix 5 according to the invention.

[0176] FIG. 11 shows an SEM image of the porous matrix 2 (with substrate 4 ) in cross-section (of the sample from FIG. 7). The thickness d of the conversion element 1 is about 40 μm. The composition and production of the conversion element KE1 will be described in the following examples.

[0177] FIG. 12 shows an SEM image of a conversion element 1 according to the invention including infiltration matrix 5 and glass substrate 4 in cross-section (of the sample from FIG. 8). The thickness d of the conversion element 1 is about 40 μm. Compared with FIG. 11, this shows that the porosity has also been significantly reduced in volume (not only at the surface) by the infiltration matrix 5. The composition and production of the conversion element KE3 will be described in the following examples.

[0178] FIG. 13 shows the performance of a porous matrix 2 (with substrate 4 ) after bonding to a chip 9 and glob topping 6 with TiO.sub.2-filled silicone in an aging test. Herein, the LEDs were operated in an environment of 85° C. and 85% rel. humidity at 1.5 A. In addition, the LEDs were switched on and off recurrently at a specified interval. Herein, the course of the Cy coordinate of the color location over a test duration of 1200h is shown. In the graph one line corresponds to one LED. After 1000h, a change of the Cy value by more than 10 points may already be observed for most LEDs indicating changes in the conversion element 1.

[0179] FIG. 14 shows the performance of a conversion element 1 according to the invention including infiltration matrix 5 (and substrate 4 ) after bonding to a chip 9 and glob topping 6 with TiO.sub.2-filled silicone in the aging test. The test conditions are comparable to those in FIG. 13, wherein it is readily apparent that the Cy value is clearly more stable over time and has changed by significantly less than 10 points even after 2000h, indicating better stability of the conversion element 1 of the invention (compared to the porous matrix 2).

[0180] Table 1 shows the measured thermal conductivity of two conversion elements KE1 and KE2 described in the following examples. The two conversion elements are comparable in terms of “basic composition” and similar in thickness, but differ in porosity, which has been reduced in conversion element KE2 by an infiltration matrix. Consequently, due to the higher thermal conductivity of the infiltration matrix compared to the gas-filled pores, the thermal conductivity of the entire conversion element is also increased.

TABLE-US-00001 TABLE 1 Thermal conductivity with and without infiltration matrix Conversion Thermal conductivity Infiltration element [λ/Wm.sup.−1K.sup.−1] matrix KE1 0.876 none KE2 1.202 includes infitration matrix

EXAMPLES

[0181] Production of a Conversion Element

[0182] Warm and cool white phosphor mixture for high CRI and R9 applications: [0183] Garnet phosphor (e.g. (Lu,Y,Gd,Tb,Ce)3(A1,Ga).sub.5O.sub.12, especially [0184] (Y,Lu,Ce).sub.3(Al, Ga).sub.5O.sub.12, especially (Lu,Ce).sub.3(Al.sub.1-xGax).sub.5O.sub.12 having a Ga content of 0% <=x<=60%) having at least one [0185] “258”: M.sub.2(Al,Si).sub.5(N,O).sub.8-type phosphor doped with Eu (M=Ca, Sr, Ba, Mg) [0186] or phosphor derived therefrom and/or [0187] “(S)CASN”: phosphor as described in EP1696016 Al or WO 2005052087 Al, the disclosure contents of which is hereby incorporated by reference, for example (Sr,Ca)AlSi(N,O).sub.3:Eu and/or [0188] a “226” phosphor having an activator content of >=0.5%, especially >=2%, especially >=3% with divalent metals such as especially Sr and/or Ca, for example Sr(Sr,Ca)Si.sub.2Al.sub.2N.sub.6:Eu

[0189] Garnet phosphor as a cool white phosphor mixture having lower CRI:

[0190] Garnet phosphor (e.g. (Lu,Y,Gd,Tb,Ce).sub.3(Al,Ga).sub.5O.sub.12, especially (Y,Lu,Ce).sub.3(Al,Ga).sub.5O.sub.12, especially (Lu,Ce).sub.3(Al .sub.1-xGa.sub.x).sub.5O.sub.12 having a Ga content of 0% <=x<=60%), especially preferably (Y, Ce).sub.3Al.sub.5O.sub.12

Example 1

Water Glass as a Matrix for a Warm White Converter (3200 K) with high CRI and R9

[0191] (Conversion Element KE1)

[0192] A suspension of water glass and aluminum phosphate as chemical curing agent, if required, is prepared with a warm white phosphor mixture (see above). Optionally, the suspension can be diluted with distilled water to adjust the viscosity. The solid to liquid mass ratio should be between 1:2 and 1:0.3 especially between 1:1.6 and 1:0.4. The suspension is applied to a substrate, for example, using a doctor blade. The doctor blade gap may be between 10-200 μm, in particular between 30-100 μm and ideally between 40-80 μm. Application rate is typically set between 1-99 mm/sec. Optionally, the conversion coating can be applied several times. Following the coating process, the freshly coated substrate is pre-dried in normal air, in a clean room or a drying oven. The room temperature and humidity can be kept constant between 18-50° C. and 0-80 g/m.sup.3, in particular between 18-30° C. and 0-50 g/m.sup.3, and ideally between 19-23° C. and 0-30 g/m.sup.3. After pre-drying, the substrate is typically scored with a diamond cutter, broken into smaller pieces for further processing and baked at temperatures between RT—450° C. for 10 to 120 min.

[0193] After hardening, any side products may optionally be removed from the conversion element in an intermediate step.

[0194] Production using a matrix of condensed monoaluminum phosphate is also possible. Infiltration with silazane

Example 2

Infiltrated with Silazane 1 (Conversion Element KE2)

[0195] A sample is prepared according to example 1 and ground after curing to match the color location. After grinding, the sample is dripped with silazane (Merck KGaA Durazene® 1500 Slow cure), and the supernatant is removed using a glass doctor knife. Curing is performed in two steps of:

[0196] 1. predrying at RT at 40-50% humidity and 2. curing at <350° C. for 4 h.

Example 3

Infiltrated with Silazane 2 (Conversion Element KE3)

[0197] A sample is prepared according to Example 1 and ground towards the color location after curing. After grinding, the sample was infiltrated with silazane 2 (type: Merck KGaA Durazene® 1500 Rapid Cure by doctoring. Curing was performed in two steps:

[0198] 1. pre-drying at RT at 40-50% humidity and

[0199] 2. curing at <350° C. for 4 h.

[0200] Optionally, multiple infiltrations may be performed to completely fill the microstructure.

[0201] Infiltrated with silicone

Example 4

Infiltrated with Silicone 1 (type: Shin-Etsu Co., Ltd. KJR9022-E-2-2L-2C) (Conversion Element KE4 )

[0202] Similar to example 3, but infiltrated with silicone.

[0203] Optionally, infiltrate multiple times and adjust viscosity using solvent to completely fill the microstructure.

Example 5

Infiltrated with Silicone 2 (type: Shin-Etsu Co., Ltd. LPS3412) (Conversion Element KE5)

[0204] Similar to example 3, except using a cold white mixture (6500 K) (see above) and infiltrated with silicone.

[0205] Optionally, infiltrate several times and adjust viscosity using solvent to completely fill the microstructure.

Example 6

Infiltrated with Silicone 2 (type: Shin-Etsu Co., Ltd. LPS3412) (Conversion Element KE6)

[0206] Similar to example 5, except using warm white mixture (3200 K) (see above) and infiltrated with silicone.

[0207] Optionally, infiltrate several times and adjust viscosity using solvent to completely fill the microstructure.

Example 7

Infiltrated with Silicone 3 (type: Shin-Etsu Co., Ltd. LPS5400) (Conversion Element KE 7)

[0208] Similar to example 3, except using cold white mixture (6500 K) (see above) and infiltrated with silicone.

[0209] Optionally, infiltrate several times and adjust viscosity using solvent to completely fill the microstructure.

[0210] Infiltration with polysiloxane is also possible.

[0211] Infiltration with water glass or monoaluminum phosphate or another aluminum phosphate is also possible.

Example 8

Water Glass Matrix Infiltrated with Silicate-Based Sol-Gel Solution (Conversion Element KE 8)

[0212] A mixture of potassium water glass (solution), aluminum phosphate as a chemical curing agent and garnet phosphor particles (YAG:Ce) is prepared. Optionally, the mixture is diluted with water. The mass ratio of solid components to liquid components in the mixture is between 1:2 and 1:0.3. The mixture is applied to flipchip wafer segments using a doctor knife to a thickness of between 10 μm and 150 μm, preferably between 15 μm and 100 μm, more preferably between 20 μm and 90 μm. Subsquently, the coated flipchip wafer segment is dried and cured at 150° C. for 2 h.

[0213] The conversion layer is subsequently coated using a silicate based sol-gel solution to infiltrate the porous structure of the water glass matrix with the silicate based sol. After drying, another infiltration step, or a curing step at 150 ° C. may be added. After curing, the pores will be filled with SiO2, which has a refractive index similar to water glass.

[0214] The silicate-based sol-gel for the infiltration matrix may be a mixture of different metal precursors or a single metal precursor, both including additives, if required. Hydrolysis may be catalyzed by acid or base.

Example 9

Water Glass Matrix Infiltrated with Silicate-Based Sol-Gel Solution (Conversion Element KE 9)

[0215] Similar to example 8, except using a warm white phosphor mixture (e.g. LuAG and CaAlSiN).

Example 10

Water Glass Matrix Infiltrated With Titanium-Based Sol-Gel Solution (Conversion Element KE10)

[0216] A mixture from potassium water glass (solution), aluminum phosphate as a chemical curing agent and garnet phosphor particles (YAG:Ce) is prepared. Optionally, the mixture is diluted with water. The mass ratio of solid components to liquid components in the mixture is between 1:2 and 1:0.3. The mixture is applied to a 6″ UX:3 chip wafer using a doctor knife, to a liquid components thickness between 10 μm and 150 μm, preferably between 15 μm and 100 μm, more preferably between 20 μm and 90 μm. The coated UX:3 chip wafer is subsequently dried and cured at temperatures between 70 ° C. and 350 ° C.

[0217] The conversion layer is subsequently re-coated with a titanium-based sol-gel solution, so that the porous structure of the water glass matrix is infiltrated with the titanium-based sol. After drying, another infiltration step, or a curing step at 300 ° C. for 1 h may be added. After curing, the pores will be filled with TiO.sub.2, which has a much higher refractive index than water glass.

[0218] Example 11:

Mixed Water Glass Matrix Infiltrated with Zirconium-Based Sol-Gel Solution (Conversion Element K11)

[0219] Similar to example 10, except using a white phosphor mixture (e.g. LuAG and CaAlSiN) and a matrix of a mixture of 50 vol.% potassium water glass and 50 15 vol.% lithium water glass. After deposition and curing of the water glass based conversion layer, the pores/channels are infiltrated with zirconium sol and cured at a temperature of 350° C.

Example 12:

Phosphor-in-Glass

[0220] A conversion solution based on a liquid inorganic glassy binder man be applied to a transparent substrate by doctor blade coating or spin coating. The substrate may be glass or sapphire. Phosphors may be oxygen-based phosphors (e.g., YAG, LuAG) or nitride- and oxynitride-based phosphors (α-SiAlON, 62-SiAlON, SCASN, CASN) or combinations thereof.

[0221] Inorganic glassy binders may be phosphate- or silicate-based, such as aluminum phosphate, potassium silicate, sodium silicate, lithium silicate, or combinations thereof. During sintering, the glassy binders form interbranched pores. The sintering conditions for the first coating of the conversion material based on inorganic glassy binder is usually >300° C. due to the required stability. Such temperatures result in certain porous structures, while the heating rate influences the degree of pore formation. After sintering, the conversion layer on the transparent substrate may be coated with a sol-gel solution by using a doctor knife or spin coating to fill the pores. The drying performance of the sol-gel solution may be adjusted by changing the base solvent, as the sol solution is to fill all pores before drying and converting to a gel. In this example, an inorganic glass binder is used as a silicate glass, such as potassium silicate glass, while a TEOS-based sol-gel solution with ethanol/water as the solvent is used as the silicate-based sol-gel solution. The phosphors are a mixture of YAG and CASN. Coating from an inorganic glass binder is performed by using a doctor knife on a glass substrate. Sintering is performed at >350° C., resulting in a porous structure. Subsequently, the conversion layer is coated with silicate-based sol-gel solution at room temperature. Drying is performed at >60° C., while sintering is performed at a temperature of >100° C. but below 200° C. The infiltrated conversion layer may subsequently be separated into the desired platelet size.

Example 13

Phosphor-in-Glass

[0222] A similar conversion solution based on liquid inorganic glassy binder may be coated on a non-transparent substrate, such as Teflon or silicone. Regardless of the phosphor used, the slight hydrophobicity of the surface of the non-transparent substrate may induce peeling of the phosphor layer after sintering. In this example, a conversion solution of alkali-containing potassium silicate mixed with YAG and CASN is coated on a slightly hydrophobic silicone wafer by using a doctor knife, spin coating, slot die coating or wire coating. The slight hydrophobicity is induced by cleaning the silicone wafer with acetone or toluene. The coated conversion layer is sintered at temperatures between 150 and 350° C., which induces formation of interconnected pores. In addition, the sintering process may induce delamination of the conversion layer from the substrate, resulting in a stand-alone phosphor-in-glass layer having a thickness of about 150 to 200 μm. The pores of the layer are filled with TEOS-based sol-gel solution by using a doctor knife or spin coating. Drying and sintering of the sol-gel material is performed at temperatures >60° C. and >100° C., respectively, but lower than 200° C. The infiltrated conversion layer may be separated into the desired platelet size.

[0223] Conversion elements according to the invention may be highly filled with phosphor, the phosphor being embedded in an inorganic matrix that initially has porosity in the form of interconnected channels, which are subsequently filled by infiltration with an infiltration material, resulting in a compact conversion element having high thermal conductivity.

[0224] The present invention is suitable for applications with high current densities (>1 A/mm.sup.2) as well as for cool white and warm white applications with high CRI (CRI≥80).

[0225] Infiltration, which may be done with the same or a different matrix-forming infiltration matrix material, fills most of the pores/channels created during curing/drying, which may result in a compact conversion element having one or more of the following advantages. For example, the low porosity of the conversion material may reduce scattering, allowing for higher efficiency of the semiconductor optoelectronic device. The amount of adhesive (e.g., silicone adhesive) that is previously required to be applied between the light source and the conversion element may significantly be reduced, or the adhesive may be avoided at all. Resorption of the adhesive may thus be avoided and, in addition, better thermal connection to the light source (e.g., the light-emitting chip) may be enabled. By reducing or avoiding the adhesive, the component size may also be reduced.

[0226] In subsequent glob topping, for example, silicone and/or silicone filled with TiO.sub.2 it may be ruled out for the potting material to penetrate into the matrix, as the pores are already and at least largely filled with the infiltration matrix. In a particular embodiment, the pores filled with the infiltration matrix may also be present only on the surfaces of the conversion element.

[0227] Subsequent processing may also be very advantageous. As the matrix is generally less elastic than, for example, a silicone matrix of prior art conversion elements, the conversion element may readily be sawn. By filling the pores with the infiltration matrix, the matrix is supported and less or no chipping occurs when sawing the conversion elements. Furthermore, due to the presence of the infiltration matrix, impurities generally do not penetrate the matrix during sawing.

[0228] In addition, conversion elements according to the invention can exhibit good grindability, improved moisture stability and improved stability at high operating currents.

[0229] By selecting the appropriate infiltration matrix having a specific refractive index, scattering properties of the conversion element may be improved.

[0230] Consequently, optoelectronic semiconductor devices, such as LEDs, may be produced with higher efficiency.

[0231] The invention is not limited thereto by the specification and the embodiments set forth therein. The invention rather encompasses any new feature as well as any combination of features, especially including any combination of features in the patent claims, even if that feature or combination itself is not explicitly stated in the patent claims or embodiments.

[0232] This patent application claims priority of German patent application 102018128536.1, the disclosure of which is hereby fully incorporated by reference.

LIST OF REFERENCE NUMBERS

[0233] 1 Conversion element

[0234] 2 Matrix

[0235] 3 Phosphor

[0236] 4 Substrate

[0237] 5 Infiltration matrix

[0238] 6 Glob top

[0239] 7 Adhesive, adhesive layer

[0240] 8 TiO.sub.2 underflow

[0241] 9 Chip