EP2351462B1 - Method for producing a luminescence conversion element, particularly an optoelectronic component - Google Patents

Description

This patent application claims the priority of the German patent application 102008052751.3 .

The present application relates to a method for producing a luminescence conversion element. Further, a luminescence conversion element and an optoelectronic device will be described.

Optoelectronic components with luminescence conversion element usually have a radiation-emitting semiconductor chip. The luminescence conversion element contains at least one phosphor. The radiation-emitting semiconductor chip emits electromagnetic radiation of a first wavelength range during operation of the component. The phosphor converts at least a portion of this radiation into electromagnetic radiation of a second wavelength range different from the first wavelength range. Such components are for example from the document WO 97/50132 known.

The luminescence conversion element in such components usually contains particles of the phosphor in a matrix of epoxy resin or of a silicone material. The thermal conductivity of the epoxy or silicone matrix material is often insufficient for satisfactory dissipation of the heat loss from the semiconductor chip of the device.

In the publication WO 01/50540 A1 For example, there is provided a surface mount light emitting diode light source and a method of manufacturing a light emitting diode light source.

It is an object of the present application to provide a versatile method for producing a luminescence conversion element.

This object is achieved by a method for producing a luminescence conversion element.

There is described a luminescence conversion element comprising a ceramic material. Expediently, the luminescence conversion element largely comprises the ceramic material. "For the most part" means that the ceramic material occupies a volume fraction of more than 50%, in particular more than 75%, preferably more than 90% of the volume of the luminescence conversion element. Particularly preferably, the luminescence conversion element consists of the ceramic material. The luminescence conversion element is provided in particular for an optoelectronic component.

The ceramic material contains phosphor particles which are connected to one another and / or with other particles to the ceramic material. The compound of the phosphor particles with one another and / or with further particles of the ceramic material is at least partially of the so-called Formed sintered necks. Alternatively or additionally, grain boundaries can also be formed between adjacent particles, in particular adjacent to each other.

The ceramic material may for example consist of the phosphor particles. Alternatively, it can contain, in addition to the phosphor particles, further particles which, in particular, have no wavelength-converting properties. The further particles comprise, for example, at least one of the following materials or consist of at least one of the following materials: aluminum oxide, aluminum nitride, boron nitride, titanium dioxide, zirconium dioxide, silicon dioxide.

In an advantageous embodiment, the phosphor particles have a mean grain diameter of less than or equal to 10 microns. In another embodiment, they have a mean grain diameter of less than or equal to 5 microns, in particular of less than or equal to 1 micron. Such phosphor particles are particularly advantageous for the wavelength conversion of the electromagnetic radiation emitted by a semiconductor chip.

In one embodiment, the further particles have an average particle diameter of less than or equal to 1 μm, in particular less than or equal to 500 nm. The average particle diameter of the further particles is preferably greater than or equal to 300 nm. Further particles having such a particle diameter can be used For example, particularly good diffusion properties can be achieved in the luminescence conversion element.

In the present case, the term "particle diameter" refers to the diameter of the smallest sphere which completely contains the phosphor particle or the further particle. Under the "Mean particle diameter" is understood in the present case to be the median of the particle diameter defined in this way, based on the number of particles. In other words, half of the phosphor particles / the further particles have a grain diameter which is larger than the mean grain diameter, and one half of the phosphor particles / the other particles have a grain diameter which is smaller than the mean grain diameter. The average grain diameter can be determined, for example, on the basis of a micrograph of a section through the luminescence conversion element. The mean grain diameter is also referred to as "d ₅₀ ".

In one embodiment, the outer surface of the luminescence conversion element has a concavely curved partial region and / or a convexly curved partial region. In particular, at least a portion of the luminescence conversion element is designed as a lens, for example as a convex lens or concave lens, in particular as a plano-convex lens or plano-concave lens.

In another embodiment, the luminescence conversion element has the form of a dome or a cap with a lid portion and at least one side wall. The sidewall or a plurality of sidewalls laterally surround the lid portion or a central area of the lid portion, such that the lid portion and the sidewall / sidewalls define an interior space. In particular, the main plane of extent of the lid portion extends obliquely or perpendicular to the / the main extension plane (s) of the side wall or the side walls. The lid portion and the at least one side wall are formed integrally in one embodiment. The interior is open in particular on the side opposite the lid section.

Furthermore, an optoelectronic component will be described. The component has a luminescence conversion element, which consists of a ceramic material. The luminescence conversion element is designed in particular according to one of the embodiments described above. Furthermore, the optoelectronic component has a radiation-emitting semiconductor chip.

The semiconductor chip is intended to emit electromagnetic radiation of a first wavelength range. The luminescence conversion element is provided to convert at least a portion of the electromagnetic radiation emitted by the semiconductor chip in the first wavelength range into a second wavelength range which is at least partially different from the first wavelength range.

If the luminescence conversion element has the form of a cap with a cover section and at least one side wall, the semiconductor chip is at least partially disposed in the cap in one embodiment of the component. In particular, the radiation-emitting semiconductor chip is arranged wholly or partly in the interior of the cap. The dimensions of the interior are chosen, for example, such that it is only suitable for receiving the semiconductor chip. The interior is in this case at most slightly larger than the semiconductor chip. In an alternative embodiment, the luminescence conversion element is spaced from the semiconductor chip. For example, it is attached to a housing of the component.

1. a) Bereitstellen eines Rohmaterials, das zur Weiterverarbeitung zu einem keramischen Material vorgesehen ist, und das Leuchtstoffpartikel und ein Bindermaterial enthält,
2. b) Formen eines Rohlings mittels Einspritzen des Rohmaterials in eine geschlossene Form,
3. c) Lösen des Rohlings aus der Form,
4. d) Entfernen des Bindermaterials aus dem Rohling, und
5. e) Sintern des Rohlings zu dem Lumineszenzkonversionselement, wobei sich die Leuchtstoffpartikel miteinander und/oder mit weiteren Partikeln des Rohmaterials zu den keramischen Materialien verbinden.

Furthermore, a method for producing the luminescence conversion element is specified. The method comprises the following steps, preferably in the order given:

1. a) providing a raw material, which is intended for further processing into a ceramic material, and contains the phosphor particle and a binder material,
2. b) forming a blank by injecting the raw material into a closed mold,
3. c) releasing the blank from the mold,
4. d) removing the binder material from the blank, and
5. e) sintering of the blank to the luminescence conversion element, wherein the phosphor particles combine with each other and / or with other particles of the raw material to the ceramic materials.

In the present context, a closed form is to be understood in particular to mean a shape which, with the exception of an injection opening and, if appropriate, of ventilation openings, is completely closed. Preferably, the mold consists of at least two sections, which can be assembled into the mold. The injection of the raw material is expediently carried out in the assembled state of the sections. The release of the blank from the mold expediently involves opening the mold, which comprises, for example, removal of at least one first portion. In particular, the blank is removed after removing at least the first portion from the other or one of the other portions.

The mold expediently encloses an interior which has the shape of the luminescence conversion element to be produced. The molding of the blank is advantageously carried out by injection into the mold, which has a correspondingly shaped interior. Thus, luminescence conversion elements of various shapes can be produced in a simple manner using the method.

For example, by injecting the raw material into the correspondingly shaped interior of the mold, a blank is formed which has the shape of a dome or cap having a lid portion and at least one side wall. In another embodiment, the mold is designed such that by means of the injection of the raw material, a blank is formed whose outer surface has a convexly curved partial region and / or a concavely curved partial region. Thus, a luminescence conversion element is produced which has a convex or concave lens, for example a plano-convex or plano-concave lens.

In a further embodiment, a raw material is provided which contains, in addition to the phosphor particles, additional particles without wavelength-converting properties. By way of example, the additional particles are aluminum oxide particles, aluminum nitride particles and / or boron nitride particles. The additional particles expediently remain as part of the ceramic material in the finished luminescence conversion element. In particular, they combine with each other and / or with the phosphor particles to form the ceramic material.

In one embodiment of the method, the raw material has phosphor particles which have an average particle diameter of less than or equal to 5 μm and in particular less than or equal to 1 μm. In another development, the average particle diameter is greater than or equal to 500 nm. In another development, the phosphor particles combine with one another and / or with further particles of the raw material during sintering to form particles having an average particle diameter of greater than or equal to 1 .mu.m, in particular greater than or equal to 5 μm.

In a further embodiment, the additional particles have an average particle diameter of less than or equal to 1 .mu.m, in particular of less than or equal to 500 nm. In a further development, the average particle diameter of the additional particles, which have no wavelength-converting properties, is greater than or equal to 200 nm.

In an expedient embodiment of the method, the binder material contains an acrylate, a polyolefin, a polyol and / or silicone or consists of at least one of these materials. Such binder materials are suitable for being removed from the blank by means of a solvent, by means of catalytic decomposition and / or by means of thermal decomposition. When removing the binder material from the blank, the binder material is preferably completely removed from the blank. But it is also possible that residues of the binder material remain in the blank.

Further advantages and advantageous refinements and developments of the method, the luminescence conversion element and the component will become apparent from the following, in conjunction with the FIGS. 1 to 4 illustrated embodiments.

Figur 1

ein Verfahren zum Herstellen eines Lumineszenzkonversionselements gemäß einem Ausführungsbeispiel in einer schematische Schnittdarstellung bei einem Stadium des Verfahrens,

Figur 2

eine schematische perspektivische Darstellung des mit dem Verfahren der Figur 1 hergestellten Lumineszenzkonversionselements,

Figur 3

eine schematische Schnittdarstellung eines Lumineszenzkonversionselements gemäß einem weiteren Ausführungsbeispiel, und

Figur 4

eine schematische perspektivische Darstellung eines optoelektronischen Bauteils mit dem Lumineszenzkonversionselement gemäß dem Ausführungsbeispiel der Figur 2.

Show it:

FIG. 1

a method for producing a luminescence conversion element according to an embodiment in a schematic sectional view at a stage of the method,

FIG. 2

a schematic perspective view of the with the method of FIG. 1 produced luminescence conversion element,

FIG. 3

a schematic sectional view of a luminescence conversion element according to another embodiment, and

FIG. 4

a schematic perspective view of an optoelectronic device with the luminescence conversion element according to the embodiment of the FIG. 2 ,

In the exemplary embodiments and figures, similar or similar elements are provided with the same reference numerals. The figures and the elements shown in the figures are not to be considered to scale. Rather, individual elements may be exaggerated in size for better representability and / or better understanding.

FIG. 1 shows a stage of a method for producing a luminescence conversion element in a schematic sectional view.

In the method, a raw material 1 is provided. The raw material in the present case consists of phosphor particles which are mixed with a binder material such as an acrylate or silicone. The raw material is provided, for example, in the form of granules.

For example, a content of the phosphor particles in the volume of the raw material 1 is 50% or more. Contains the raw material additional particles, such as alumina particles or aluminum nitride particles, for example, the proportion of the phosphor particles and the additional particles together is 50% or more, especially 70% or more, of the volume of the raw material 1.

The provided raw material 1 is transported by means of a tool 2, to a mold 3. In this case, the raw material 1 is heated, so that the binder material melts and the raw material passes into a flowable state. The tool 2 has, for example, a storage container for the raw material, a heated tube with a screw conveyor and a die 3 facing nozzle. The raw material 1 is transported from the reservoir through the heated tube where the binder material is melted to the nozzle. The raw material is heated, for example, to a temperature between 100 ° C and 200 ° C. Preferably, the mold 3 is also heated to a temperature between 100 ° C and 200 ° C.

By means of the nozzle, the flowable raw material 1 is injected through an injection channel 300 of the mold 3 into an interior 30 of the heated mold 3. The injection pressure with which the raw material 1 is injected from the tool 2 into the mold 3 is, for example, between 500 bar and 1000 bar.

The mold 3 is presently completely closed except for the injection channel 300. In other words, the internal space 30 of the mold is connected to the environment of the mold 3 only through the injection channel 300.

For example, to reduce the risk of trapped air in the interior 30 of the mold 3 during injection of the raw material 1, the interior of the injection prior to a Embodiment of the method to be evacuated. In an alternative variant (in FIG. 1 not shown), the mold 3 has at least one vent passage through which air or another gas contained in the inner space 30 before injection can escape during the injection of the raw material 1 into the inner space 30.

By injecting the raw material, a blank is produced which has the shape of the interior 30 of the mold 3. The blank is subsequently released from the mold 3. For this purpose, the portions 31 and 32, from which the mold 3 is composed, separated from each other, so that the blank is exposed and can be removed from one of the sections 31 or 32. Prior to loosening the blank from the mold 3, cooling of the mold 3 with the blank to a lower temperature than intended for injection can be expedient, for example to increase the stability of the blank.

Subsequently, the binder material of the raw material 1 is removed from the blank. For example, it is washed out of the blank with a solvent process.

Subsequently, the blank is sintered at a high temperature, for example, 1000 ° C or more, whereby the phosphor particles combine with each other and / or with the additional particles of the raw material to the ceramic material.

FIG. 2 shows a schematic perspective view of the method with reference to the exemplary embodiment of FIG. 1 produced luminescence conversion element 4th

In the present embodiment, the luminescence conversion element 4 has the shape of a cap. The cap has a lid portion 41 with a central region 400 laterally surrounded by four outer walls 42. The lid portion 41 and the side walls 42 extending perpendicular to the lid portion 41 define an interior of the cap 4.

In the present case, the cap 4 has a recess 43. For example, in plan view of the lid portion 41, apart from the recess 43, rectangular or square cap, a corner is missing.

The luminescence conversion element 4 may, for example, have a circumferential ridge 44 or a plurality of ridges which is due to the production in the two-part mold 3. At the junction between the first portion 31 and the second portion 32 of the mold 3, for example, the raw material 1 when injecting into the inner space 30 pass in a small amount between the sections 31 and 32, whereby the finished luminescence conversion element 4 or - depending on the composition of Form - several burrs 44 can remain. Alternatively or additionally, as shown in FIG. 3, a projection or depression 45 may remain at the location of the luminescence conversion element 4, where the injection of the raw material has taken place through the injection channel 300 of the mold. Any existing burrs 44 or residues 45 from the injection channel may also be removed in the finished luminescence conversion element 4.

The FIG. 3 shows a further exemplary embodiment of a luminescence conversion element 4 in a schematic cross section. The luminescence conversion element 4 is according to the embodiment of the FIG. 3 in contrast to the embodiment of FIG. 2 not shaped as a cap but as a plate. A central region 400-seen in plan view on the main extension plane of the plate-is designed as a plano-convex lens 5.

FIG. 4 shows a schematic perspective view of an optoelectronic device with the luminescence conversion element 4 according to the embodiment of the FIG. 2 ,

The optoelectronic component has a lead frame 7. On a first portion of the lead frame 7, a radiation-emitting semiconductor chip 6 is attached. The luminescence conversion element 4 is slipped over the semiconductor chip 6 as a cap. In the present case, the semiconductor chip is arranged completely in the interior of the cap-shaped luminescence conversion element 4 except for a corner area which is left free by the luminescence conversion element 4 by means of the recess 43. In particular, the cover portion 41 of the cap 4 covers the major surface of the semiconductor chip 6 remote from the lead frame 7, apart from the corner region. The side walls 42 of the cap 4 extend laterally around the semiconductor chip 6 and cover its side edges.

The exposed corner region of the semiconductor chip 6 has an electrical connection surface 60, in particular a bond pad, on its surface facing away from the leadframe 7. A bonding wire 8 connects the bonding pad 60 to a second portion of the electrical lead frame 7, which is electrically isolated from the first portion. Advantageously, the assembly of the provided with the recess 43 Lumineszenzkonversionselements 4 before or after the electric Contacting the semiconductor chip 6 by means of the bonding wire 8 done.

The optoelectronic component, which is, for example, a light-emitting diode component, in one embodiment has a reflector trough, which is formed, for example, from a plastic material, with which the lead frame is encapsulated. The reflector tray is omitted in the present case for simplified illustration.

Claims (9)

1. Method for producing a luminescence conversion element (4), in particular for an optoelectronic component, comprising the following steps:

   a) Providing a raw material (1), which is provided for further processing to form a ceramic material and contains phosphor particles and a binder material,

   b) moulding a blank by means of injecting the raw material (1) into a closed mould (3),

   c) releasing the blank from the mould (3),

   d) removing the binder material from the blank, and

   e) sintering the blank to form the luminescence conversion element (4), wherein the phosphor particles combine with one another and/or with further particles of the raw material to form the ceramic material.
2. Method according to Claim 1, wherein the mould is embodied in such a way that a blank whose outer surface has a convexly curved partial region and/or a concavely curved partial region is moulded by means of the raw material (1) being injected.
3. Method according to either of Claims 1 and 2, wherein a blank is moulded which has the shape of a dome or the shape of a cap having a cover section and at least one side wall.
4. Method according to any of the preceding claims, wherein a raw material is provided which additionally contains particles without wavelength-converting properties.
5. Method according to Claim 4, wherein the particles without wavelength-converting properties comprise aluminium oxide, aluminium nitride, boron nitride, titanium dioxide, zirconium dioxide and/or silicon dioxide.
6. Method according to either of Claims 4 and 5, wherein the particles without wavelength-converting properties have an average grain diameter of less than or equal to 1 µm, in particular of less than or equal to 500 nm.
7. Method according to any of the preceding claims, wherein the phosphor particles in the raw material have an average grain diameter of less than or equal to 5 µm, in particular of less than or equal to 1 µm.
8. Method according to any of the preceding claims, wherein the binder material contains an acrylate, a polyolefin, a polyol and/or silicone.
9. Method according to any of the preceding claims, wherein the binder material is removed by means of a solvent, by means of catalytic decomposition and/or by means of thermal decomposition.

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