Conversion element, component and process for producing a component

Abstract

A conversion element, a component and a method for producing the component are disclosed. In an embodiment the conversion element includes a phosphor configured to convert electromagnetic primary radiation into electromagnetic secondary radiation and a glass composition as matrix material in which the phosphor is embedded. The glass composition has the following chemical composition: at least one tellurium oxide with a proportion of 65 mole % as a minimum and 90 mole % as a maximum, R.sup.1O with a proportion of between 0 mole % and 20 mole %, at least one M.sup.1.sub.2O with a proportion of between 5 mole % and 25 mole %, at least one R.sup.2.sub.2O.sub.3 with a proportion of between 1 mole % and 3 mole %, M.sup.2O.sub.2 with a proportion of between 0 mole % and 2 mole %, and R.sup.3.sub.2O.sub.5 with a proportion of between 0 mole % and 6 mole %.

Claims

1. A conversion element comprising: a phosphor configured to convert electromagnetic primary radiation into electromagnetic secondary radiation; and a glass composition as matrix material in which the phosphor is embedded, wherein the glass composition has the following chemical composition: at least one tellurium oxide with a proportion of 65 mole % as a minimum and 90 mole % as a maximum; R.sup.1O with a proportion of between 0 mole % and 20 mole %, wherein R.sup.1 is selected from Mg, Ca, Sr, Ba, Zn, Mn and combinations thereof; at least one M.sup.1.sub.2O with a proportion of between 5 mole % and 25 mole %, wherein M.sup.1 is selected from Li, Na, K and combinations thereof; at least one R.sup.2.sub.2O.sub.3 with a proportion of between 1 mole % and 3 mole %, wherein R.sup.2 is selected from Al, Ga, In, Bi, Sc, Y, La, rare earths and combinations thereof; M.sup.2O.sub.2 with a proportion of between 0 mole % and 2 mole %, wherein M.sup.2 is selected from Ti, Zr, Hf and combinations thereof; and R.sup.3.sub.2O.sub.5 with a proportion of between 0 mole % and 6 mole %, wherein R.sup.3 is Nb and/or Ta.

2. The conversion element according to claim 1, wherein the glass composition is free of boron trioxide, germanium oxide, phosphates, halides, P.sub.2O.sub.5 and SiO.sub.2, and wherein the glass composition has a glass transformation temperature of less than 320 C. and a dilatometric softening temperature of less than 400 C.

3. The conversion element according to claim 1, wherein the tellurium oxide in the glass composition is TeO.sub.2 and has a proportion of 67 mole % as a minimum and of 69 mole % as a maximum.

4. The conversion element according to claim 1, wherein R.sup.1O in the glass composition has a proportion of between 14 mole % and 18 mole %.

5. The conversion element according to claim 1, wherein M.sup.1.sub.2O in the glass composition has a proportion of between 8 mole % and 14 mole %.

6. The conversion element according to claim 1, wherein the glass composition is free of boron trioxide, germanium oxide, phosphates, halides, P.sub.2O.sub.5 and SiO.sub.2.

7. The conversion element according to claim 1, wherein R.sup.2 is selected from the group consisting of Al, La, Y and Bi, and wherein R.sup.2.sub.2O.sub.3 has a proportion of between 1.5 mole % and 2.5 mole %.

8. The conversion element according to claim 1, wherein the glass composition consists essentially of tellurium oxide, M.sup.1.sub.2O and R.sup.2.sub.2O.sub.3, and wherein R.sup.2.sub.2O.sub.3 has a proportion of between 1.5 mole % and 2 mole %.

9. The conversion element according to claim 1, wherein the glass composition has a glass transformation temperature of less than 320 C. and a dilatometric softening temperature of less than 400 C.

10. The conversion element according to claim 1, wherein the glass composition is radiolucent, and wherein at least 90% of an incidental electromagnetic radiation is transmitted from a wavelength range of 380 nm to 800 nm.

11. A component comprising the conversion element according to claim 1.

12. The component according to claim 11, wherein the component comprises a semiconductor chip configured to generate the electromagnetic primary radiation of at least a blue spectral range, and wherein the conversion element is arranged directly on the semiconductor chip.

13. The component according to claim 11, wherein the component comprises a semiconductor chip, and wherein the conversion element is spatially separated from the semiconductor chip.

14. The component according to claim 11, wherein the component comprises a semiconductor chip or a substrate, wherein the semiconductor chip is configured to generate the electromagnetic primary radiation of at least a blue spectral range, wherein the conversion element connects an additional layer with the semiconductor chip or the substrate, and wherein the additional layer is a ceramic conversion element.

15. A method for producing a component, the method comprising: providing at least one semiconductor chip, which has a radiation exit surface, or a substrate; attaching the conversion element pursuant to claim 1 on the radiation exit surface or on the substrate; and heating the component to a maximum of 400 C., so that a composite is generated between the radiation exit surface or the substrate and the conversion element.

16. The method according to claim 15, wherein attaching the conversion element on the radiation exit surface or the substrate comprising the conversion element as powder or as prefabricated body.

17. The method according to claim 15, wherein the conversion element is generated by a glass composition designed as a layer, the glass composition being coated with at least one phosphor, and wherein the phosphor subsequently sinks into the glass composition.

18. The method according to claim 15, wherein the conversion element is generated by introducing a phosphor into the glass composition and subsequently attaching such phosphor-glass composition mixture on the radiation exit surface or to the substrate.

Description

BRIEF DESCRIPTION OF THE DRAWINGS

(1) A glass composition, a component as well as a method for producing a component are described in more detail in the following with reference to the drawing on the basis of embodiments. Identical reference signs indicate identical elements in the individual illustrations. However, no true-to-scale references are made. Instead, individual elements can be shown in an exaggeratedly large manner for the sake of better understanding.

(2) Shown in:

(3) FIG. 1 are embodiments A1 to A7 of a matrix material as well as comparative examples V1 to V4,

(4) FIG. 2 is a transmission spectrum of an embodiment,

(5) FIG. 3 is an x-ray diffraction diagram of an embodiment,

(6) FIG. 4 is a transmission spectrum of an embodiment,

(7) FIG. 5 is a transmission spectrum of an embodiment,

(8) FIG. 6 is a comparison of x-ray diffraction diagrams of three embodiments, and

(9) FIG. 7 to 12 are a schematic side view of a component pursuant to an embodiment in each case.

DETAILED DESCRIPTION OF ILLUSTRATIVE EMBODIMENTS

(10) FIG. 1 shows embodiments A1 to A7 of the matrix material in tabular form. The table also shows comparative examples V1 to V4 of conventional matrix materials. The values stated in the table indicate a maximum error of 5%. No phosphor is embedded in this matrix material. The matrix material of the embodiments A1 to A7 comprises tellurium oxide, in particular tellurium oxide TeO.sub.2. The proportion of tellurium oxide in A1 to A7 equals between 67 mole % and 69 mole %. In particular, the proportion of tellurium oxide equals between 67.5 mole % and 68.5 mole % inclusively.

(11) The matrix material further comprises R.sup.1O as zinc oxide. The proportion of zinc oxide equals between 18 mole % and 20 mole % inclusively.

(12) The matrix material further comprises M.sup.1.sub.2O in the form of disodium oxide. The proportion of disodium oxide in the matrix material equals between 10 mole % and 12 mole % inclusively.

(13) The matrix material further comprises an oxide of a trivalent metal, such as, for example, aluminum trioxide, lanthanum trioxide, bismuth trioxide and/or yttrium trioxide. The proportion of the oxide of the trivalent metal equals between 1.5 mole % and 2.5 mole %.

(14) Furthermore, FIG. 1 shows the glass transformation temperatures T.sub.g relating to the embodiments A1 to A7 and determined by means of dilatometry in C. The glass transformation temperatures equal between 283 C. and 294 C. In particular, the glass transformation temperatures of the matrix material equal <295%.

(15) Furthermore, FIG. 1 shows the associated thermal expansion coefficients x and the softening temperatures T.sub.e of the embodiments A1 to A7 in C. T.sub.e equals between 308 C. and 323 C. and was determined by means of dilatometry.

(16) Furthermore, FIG. 1 shows a refractive index n for the embodiments A2, A5 and A6 of approximately 2, which was determined at a wavelength of 546.06 nm.

(17) The comparative examples V1 to V4 are shown in comparison. The comparative examples A1 to A7 differ from the embodiments A1 to A7 in particular due to the face that the matrix material of V1 to V4 has no oxides of trivalent metals. Accordingly, the comparative examples have higher softening temperatures T.sub.e of 329 C. (V2, V4) and/or a high crystallization tendency (V1, V3), in particular during production. The comparative examples are thus not very suitable in a conversion element in which temperature-sensitive phosphors are also embedded, for example.

(18) FIG. 2 shows a transmission spectrum for the embodiment A2, which is shown in the table of FIG. 1. Shown is the transmission T in % in dependency upon the wavelength in nm. The curve 1 shows the matrix material before a weathering test, wherein the wall thickness WD of the sample WE=0.89 nm. The curve 2 shows the transmission curve of the matrix material of A2 after conducting the weathering test. Said weathering test ensued in such a way that the matrix material was exposed to a temperature of 85 C. with a relative humidity of 85% and over 1000 hours. A comparison of the matrix material before (curve 1) and after (curve 2) the weathering test essentially shows no difference in transmission. It can thus be concluded that the matrix material did not change during the test. The material matrix of embodiment A2 is thus particularly weather-resistant and corrosion-resistant and very suitable for a conversion element.

(19) FIG. 3 shows an x-ray diffraction diagram of embodiment A2 pursuant to the table in FIG. 1. The intensity I in a.U. (arbitrary units) in dependency upon 2 is shown in . It is evident from the graphic that the matrix material is present in a purely amorphous and non-crystalline state. This is advantageous, as this in particular means that the matrix material scatters no electromagnetic radiation from the visible range.

(20) FIG. 4 shows a transmission spectrum of embodiment A6 in the table in FIG. 1. The transmission T in % in dependency upon the wavelength is shown in nm. The curve 1 shows the transmission of the matrix material with a wall thickness of 0.98 nm before the weathering test, the curve 2 shows the transmission of the matrix material after the weathering test. The transmission does not change due to the influence of temperature, relative humidity and over time (1000 hours) in the total wavelength range of 200 nm to 1000 nm.

(21) FIG. 5 shows a transmission spectrum of embodiment A7 in the table in FIG. 1. The transmission T in % in dependency upon the wavelength is shown in nm and measured against a wall thickness of 0.96 nm. The transmission curves are shown before (curve 1) and after (curve 2) the weathering test. A comparison of the matrix material before (curve 1) and after (curve 2) the weathering test essentially shows no difference in transmission. It can thus be concluded that the matrix material did not change during the test. The embodiment A7 is also weather-resistant.

(22) FIG. 6 shows an x-ray diffraction diagram of embodiment A2, A5 and A6 pursuant to the table in FIG. 1. The intensity I in a.U. (arbitrary units) in dependency upon 2 is shown in . It is evident from the graphic that the matrix material in A2, A5 and A6 is purely amorphous and contains no crystals. This is advantageous, as this in particular means that the matrix material scatters no electromagnetic radiation from the visible range.

(23) FIG. 7 shows a component 10 pursuant to an embodiment. In particular, said component 10 is an optoelectronic component. In other words, the component 10 is set up to emit electromagnetic radiation, particularly in the visible range. The component 10 has a semiconductor chip 1. A conversion element 2 is arranged in direct contact on this semiconductor chip 1. Said conversion element 2 comprises a glass composition 2a as matrix material and at least one phosphor 2b. Said phosphor 2b is set up for absorbing the primary radiation emitted by the semiconductor chip 1, wherein said primary radiation is converted at least partially into electromagnetic secondary radiation. The conversion element 2 is attached directly on the radiation exit surface 11 of the semiconductor chip 1. The glass composition 2a serves here to embed the phosphor 2b. Furthermore, the glass composition 2a demonstrates higher heat conductivity as matrix material than silicone, and therefore the heat generated in the conversion element 2 is easier to dissipate from the glass composition 2a and the phosphor suffers less damage, which increases the efficiency of the optoelectronic component. Simultaneously, the direct connection of conversion element and radiation exit surface increases the efficiency of the semiconductor chip, as the higher refractive index and the higher heat conductivity of the glass composition allow both the light outcoupling and the efficiency to be improved.

(24) A garnet phosphor, for example, a yellow garnet phosphor, a nitridic phosphor, for example, a red-emitting nitridic phosphor, aluminates, orthosolicates, sulphides or Calsine can be used as phosphor. In principle, however, all phosphors can be used that are set up for converting electromagnetic primary radiation into electromagnetic secondary radiation.

(25) The conversion element 2 in FIG. 7 is designed in a platelet form. The conversion element 2 preferably has a thickness of 1 m to 200 m, in particular between 5 m and 100 m, for example, 30 m. The platelet-shaped conversion element advantageously covers at least 80% of the radiation exit surface 11 of the semiconductor chip 1. The basal area of the conversion element 2 is preferably congruent or almost congruent with the basal area of the semiconductor chip 1 in a top view of the component 10. In a particular embodiment the basal area of the conversion element 2 can also be greater than the basal area of the semiconductor chip 1.

(26) Alternatively, a vitreous, ceramic or metallic substrate can also be used in place of the semiconductor chip 1, on which the conversion element 2 is attached and, for example, used for transmitting or reflecting laser applications. The laser can have an optical performance of 1 watt as a minimum and/or 20 watts as a maximum. The substrate can also have functional oxidic coatings that act, for example, as passivation, as protective film or as optical element. Such layers as well as layer stacks can be amorphous, crystalline or semi-crystalline and connected with the vitreous conversion element 2. In a particular embodiment the conversion element 2 can be produced on a transmitting substrate and then secured on a semiconductor chip 1. In such case, the substrate is preferably facing away from the semiconductor chip 1.

(27) The embedding of the phosphor 2b in the glass composition 2a preferably ensues by means of a softening, sinking into, sinking onto, melting into and/or sinter process. For example, the phosphor 2b is mixed with the pulverized glass of the glass composition 2a and a paste produced therefrom, which is subsequently screen printed or dispensed onto a substrate and then vitrified. If need be, this can also ensue subject to negative pressure and/or with weight application.

(28) Alternatively, the surface of the prefabricated body of the glass composition 2a can be coated with a phosphor 2a. The coating can, for example, ensue by printing, screen printing, spraying, knife-coating, dispensing or spin-coating. The component 10 can subsequently be treated at a temperature of 350 C. for 30 minutes, for example. This causes the phosphor 2b to sink into the glass composition 2a. If need be, this can ensue with weight application. This allows a conversion element 2 to be generated, which comprises the glass composition 2a as matrix material and a phosphor 2b. The conversion element 2 demonstrates high quantum efficiency (QE) of 90% as a minimum compared with a conventional conversion element containing silicone as matrix material with the same phosphor.

(29) The following table shows the relative quantum efficiency when using the glass composition of the embodiment A8 in conjunction with a phosphor, for example, a yellow garnet phosphor or a red nitridic or a warm white mixture. A conversion element with the same phosphor powder in the silicone matrix was used as reference.

(30) TABLE-US-00001 Conversion element 2 comprising one of the following phosphors 2b and the glass composition 2a of the embodiment A8 Relative QE/% Yellow garnet phosphor 90 Red nitridic phosphor 90 Warm white mixture 90

(31) FIG. 8 shows a schematic side view of a component pursuant to an embodiment. FIG. 8 differs from the embodiment of FIG. 7 in that the conversion element is designed as beam-shaped element. In particular, the conversion element 2 has a convex lens shape. Said conversion element 2 is thus already designed as an integrated lens, wherein said lens can be created, for example, by a specific shaping or by the surface tension of the glass when heating the conversion element 2.

(32) The primary radiation emitted by the semiconductor chip 1 can be specifically guided through a conversion element 2 designed in such a way as lens or as beam-shaped element. In particular, this allows the radiation emitting angle of the primary radiation emitted by semiconductor chip 1 to be specifically changed and/or corrected. The conversion element 2 thus influences, inter alia, the radiation emitting characteristic and the directionality as well as the color location of the radiation emitted by the component.

(33) Furthermore, the embodiment in FIG. 8 has an additional element compared with the embodiment in FIG. 7. The additional element 2c is also embedded in the glass composition 2a. In particular, the additional element 2c is distributed homogeneously in the glass composition 2a. The additional element 2c preferably increases the refractive index of the glass composition 2a. A refractive-index-increasing additional element is, for example, La.sub.2O.sub.3. For the rest, the embodiment in FIG. 8 corresponds to the embodiment in FIG. 7. This additional element 2c can additionally or alternatively specifically influence the light scattering and thus serve to better outcouple and homogenize the light. The additional element 2c can be a scattering particle, for example, TiO.sub.2, A1.sub.2O.sub.3, SiO.sub.2. The scattering particles can be distributed non-homogeneously in the glass composition 2a or be designed as separate layer. Said separate layer can be arranged above or below the matrix material or the glass composition 2a. Alternatively, the specific scattering can also ensue via roughening of the surface.

(34) FIG. 9 shows a schematic side view of a component 10 pursuant to an embodiment. The component 10 comprises a semiconductor 1, which is completely enclosed by a conversion element 2 on the radiation exit surface 11 and on the lateral surfaces thereof. The conversion element 2 comprises a phosphor 2b and the glass composition 2a as matrix material. An additional layer 3 is directly attached to the conversion element 2. The additional layer 3 can in turn comprise a phosphor. Said phosphor of the additional layer 3 can be embedded in a matrix material. The above-described glass composition, silicone, another glass or a ceramic is suitable as a matrix material. The component 10 has two conversion layers, preferably with different phosphors. The additional layer 3 can be firmly connected with the semiconductor chip 1 via the conversion element 2. In the event of silicone, the latter cannot be attached until after the temperature treatment.

(35) Alternatively, the additional layer 3 can be designed as casting compound (not shown here). In particular, the semiconductor chip 1 is advantageously completely enclosed by the conversion element 2 and the additional layer 3.

(36) FIG. 10 shows a schematic side view of a component 10 pursuant to an embodiment. Unlike the embodiment in FIG. 9, the component 10 shows a conversion element, which is designed as a casting compound, wherein said casting compound is additionally formed as beam-shaped element. In particular, the casting compound 2 or the conversion element 2 has a convex lens shape. This allows the radiation emitting characteristic and directionality of the primary radiation emitted by the semiconductor chip 1 to be specifically changed or corrected.

(37) The conversion element 2 further comprises a phosphor 2b, a glass composition 2a and an additional element 2c. The components embedded in the glass composition 2a, such as phosphor 2b and additional element 2c, are preferably substantially evenly distributed in the glass composition 2a. Alternatively or additionally, the conversion element 2 can have an additional subordinate layer 3, which can comprise a component with radiation-absorbing properties. Said component preferably absorbs radiation in the wavelength range of 400 nm, preferably in the wavelength range of 380 nm. This allows organic components of the component 10, such as a plastic housing, for example, to be protected against short-wave radiation and any damage caused by implication, such as discolorations, for example.

(38) FIG. 11 shows a schematic side view of a component 10 pursuant to an embodiment. The semiconductor chip 1 is arranged on the carrier 5. Said semiconductor chip has a subordinate conversion element 2, which comprises the glass composition 2a as matrix material and the phosphor 2b. An intermediate chamber is designed between the conversion element 2 and the semiconductor chip 1. A gas, for example, air, is preferably arranged in the intermediate chamber 8. The conversion element 2 is not directly attached to the radiation exit surface 11 of the semiconductor chip 1.

(39) FIG. 12 shows a schematic view of a component 10, for example, of an optoelectronic component, pursuant to an embodiment. The semiconductor chip 1 is arranged on a carrier 5. A conversion layer 2 is subsequently arranged. An additional layer 3 is subordinate to the conversion layer 2. Said additional layer 3 can in turn comprise a phosphor. The additional layer 3 is in particular designed in ceramic, preferably an oxidic garnet ceramic (YAG:Ce, LuAG:Ce, etc.). The component 10 can be produced by providing a carrier 5 and attaching a semiconductor chip 1. The conversion element 2 can subsequently be attached to the radiation exit surface 11 of the semiconductor chip 1. The conversion element 2 can thereby be attached as prefabricated body, for example, as platelet, or as powder. Said prefabricated body in particular comprises at least one phosphor 2a, the color location of which preferably differs from the additional layer 3. That means that the color location of the prefabricated additional layer 3 is specifically changed by the conversion layer 2, with a red-emitting phosphor preferably being introduced. The attachment of the conversion element 2 and/or the additional layer 3 as platelet can ensue in a so-called pick-and-place process on the radiation exit surface 11 of the semiconductor layer sequence 1.

(40) The connection of the additional layer 3 with the semiconductor chip 1 ensues via the conversion layer 2 by heating to 350 C. as a maximum, subject to weight application and/or negative pressure, if need be.

(41) Such a structure has the advantage that ceramic conversion elements, which can only be produced in certain colors, can cover an extended color range in this way, as the phosphor 2b in the vitreous matrix material 2a, for example, also allows a warm white radiation emitting characteristic of the component to be generated.

(42) Alternatively, a metallic, vitreous or ceramic substrate can also be used instead of the semiconductor 1. In particular, the substrate is suitable for laser applications or remote phosphor applications, for example. The substrate can also comprise functional oxidic coatings that, for example, act as passivation, protective film or as optical element. Such layers as well as layer stacks can also be amorphous, crystalline or semi-crystalline and connected with the vitreous conversion element 2.

(43) In addition, in a further step, the ridge of the conversion element 2 is removed and/or straightened. In particular, after removing and/or straightening the ridge, the lateral sides of the additional layer 3, of the conversion element 2 and of the semiconductor chip 1 end flush.

(44) The description on the basis of the embodiments does not limit the invention to such; instead said invention comprises every feature as well as every combination of features, which in particular includes every combination of features in the claims, even if such feature or such combination is not itself explicitly stated in the claims or embodiments.