WO2012163655A1

WO2012163655A1 - Method for producing encapsulated light emitting diode with wavelength converters inside the encapsulation

Info

Publication number: WO2012163655A1
Application number: PCT/EP2012/058825
Authority: WO
Inventors: Harald JÄGER; Hans-Christoph Gallmeier; Herbert Brunner
Original assignee: Osram Opto Semiconductors Gmbh
Priority date: 2011-05-27
Filing date: 2012-05-11
Publication date: 2012-12-06
Also published as: DE102011102590A1

Abstract

A method is disclosed for producing a multiplicity of light emitting diode components of the same type, each comprising at least one light emitting diode chip (3) and a conversion means, to which an injection-moulding compound (2) that surrounds the light emitting diode chip (3) is added, and which wavelength converter converts the wavelength of at least part of a primary electromagnetic radiation emitted by the at least one light emitting diode chip (3).

Description

description

The invention relates to a method for producing light-emitting diode components, in which at least part of a light emitted by a light-emitting diode chip,

Primary radiation is wavelength converted. Nowadays, light-emitting diode components with different colors are possible. For this purpose, the light-emitting diode component has a light-emitting diode chip, also known as LED. In order to reach the desired color location, the primary radiation emitted by the LED is radiated onto a conversion medium. In this, the primary radiation of the LED becomes a

Secondary radiation of the desired color location converted.

At least in-house are manufacturing processes of

Light-emitting diode components, the at least a portion of, emitted by an LED, primary radiation

wavelength conversion, by so-called "CLC Layer

In this case, a flat converter plate is glued directly to the chip, the "wire bond päd" is thereby omitted, so that the chip can then be wire-contacted.

A central arrangement of the chip connections is here

unsuitable because of the risk of adhesive contamination and associated poor bondability.

Due to the flat converter plate in combination with special chip designs or also due to transparent adhesives, inhomogeneities of the color locus, for example the so-called "blue piping" in light-emitting diodes, occur blue primary radiation, over the beam angle of the

Light source. Particularly affected are the

Margins, where insufficient conversion

takes place.

Likewise, the method of volume conversion is known. In this case, the light-emitting diode chip is wrapped after wire contacting with a potting material to which the converter is already mixed. The wrapping of the chip happens by casting.

The disadvantage of this method is that it by the so-called "Stokes shift" to a heating of the

Potting material comes, which is determined by the potting height. Under "Stokes shift" is generally the effect

understood that the light emitted by fluorescent means is shifted towards longer wavelengths; So there is a "redshift". The heating can lead to a thermal overstressing of the

Potting materials come through cracks in the

Potting material and characterized by converter aging or converter quenching. As converter quenching, also known as converter quenching, processes are referred to, which result in a decrease in the intensity of the fluorescence of a fluorescence agent, without the

Fluorescent agent is destroyed. This is no longer adequate conversion and it comes to inhomogeneities of the color location. Particularly affected by this are

High current applications, so-called high-power designs.

In addition, light-emitting devices are characterized by

Volume conversion can be made due to their

Surface radiation produced not suitable for imaging systems. The object of the present invention is to develop a method for the production of light-emitting diode components with a conversion element which avoid inhomogeneities of the color locus or chromaticity variations and achieve improved color homogeneity over the emission angle.

This object is achieved by a method according to the independent claims. Advantageous developments are specified in the dependent claims.

In accordance with at least one embodiment of the method described here, a multiplicity of similar light-emitting diode components, each having one LED and one LED

Conversion, which wavelength-converted at least a portion of a radiation emitted by an LED produced by applying to the wafer by spraying technique radiation and thermally stable material, the

Conversion agent added is applied.

Here, the wafer is introduced with the light-emitting diode chips in a cavity of an injection mold, in which in a further step, a spray mass is driven. This spray mass is mixed with a conversion agent and is driven in such a way that the entire wafer surface

is uniformly covered. Subsequently, the injection mold is removed and the light-emitting diodes light sources from the

Wafer composite are isolated.

In accordance with at least one embodiment of one here

described method is the driving of the

Spritzmasse, which is mixed with conversion agents, in the cavity such that the light-emitting diode chips are surrounded by a uniform layer of injection molding compound.

In this case, "uniform" may in particular mean that the light-emitting diode chips are exposed along their entire length

Outside surface are covered with the spray mass, wherein the

Distance of the outer surface of the injection molding material from the exposed outer surface of a light-emitting diode chip is substantially constant. That is, even side surfaces of the LED chips, which run, for example, obliquely to the main surface of the LED chips, are covered with the spray mass. This reduces the risk of the so-called "blue piping", "blue piping" means that, for example, in a blue light emitting LED chip in which a part of the light is converted in such a way that a total of

LED chip and conversion white light

is emitted, an emission of bluish light from the region of the side surfaces of the LED chip is visible, if the LED chip is not surrounded with a uniform layer of injection molding compound.

With the procedure it is possible completely covered

Produce light-emitting diode chips, resulting in a significant reduction or avoidance of inhomogeneities of the color location.

Preferably, silicone with attached converter is used as the sprayed material. The spray mass may contain at least one light source. For example, inorganic substances such as garnets doped with rare earths or nitrides are suitable for this purpose. Other suitable bulbs, such as

rare earth-doped aluminates or orthosilicates are known from WO 98/12757. In an extended embodiment, particles are added to the silicone-converter mixture SiO 2 ^_ to prevent the silicone from thermal damage and the converter from aging

or to protect quenching.

In alternative embodiments may be used as filler an epoxy-silicone hybrid or other radiation and thermally ^¬ stable materials. In addition, additional thermally conductive material can be added to these combinations of filler material and converter.

In an expedient development of the method, the injection mold is designed such that results in a smooth, even surface of the spray mass.

Alternatively, the injection mold is designed such that the cover of the chip is designed in three dimensions, for example in the form of a dome. As a result, an improvement in the color homogeneity over the emission angle is achieved at the same time.

In an advantageous embodiment of the method, the "wire bond päd" of the chip is kept free of injection molding compound in order to enable wire bonding of the chip. This is done suitably by removal of the mass, over the relevant electrical contacts, by means of laser.

In an alternative embodiment, the injection molding tool is designed such that it directly seals the bond contact and thus keeps it free of potting material.

In a further embodiment, the "wire bond päd" by means of a film applied thereto before potting

protected. In a particularly advantageous embodiment of the method, a connection contact, the so-called "bond päd", is protected by application of a photoactive layer, which in the

Connection can be removed again. This can be realized, for example, by wet-chemical methods.

Suitably, the light-emitting diode chips after wrapping, by means of sawing the wafer, isolated.

Due to the complete coverage of the chip including the mesa with converter-filled potting material, inhomogeneities of the color location are considerably reduced or avoided. According to alternative methods, a plurality of

pre-sorted light-emitting diode chips arranged to form an artificial wafer and this introduced into a cavity of an injection mold, in which in a further step a

Injected mass is injected. This spray mass is mixed with conversion means and is driven in such a way that the entire wafer surface is uniformly covered. Subsequently, the injection mold is removed and the

Light-emitting diode components from the artificial wafer composite are isolated.

In the present case, a placement of wavelength-predefined light-emitting diode chips into an artificial wafer takes place. For example, it can only light-emitting diode chips, the one

common class of LED chips (also Bin)

are assigned, are arranged to the artificial wafer. Since all light-emitting diode chips of the artificial wafer are surrounded with a uniform layer of injection molding compound in such a way that the thickness of the injection molding compound is above each light-emitting diode chip takes the same course, arise after the separation of light emitting diode components that emit, for example, white mixed light from a narrow Farbortbereich. Another one

Sorting of the light-emitting diode components with respect to

Color location can then be omitted. "Uniform" means, among other things, that the course of the spray mass over each LED chip is the same. That is, within the scope of the manufacturing tolerance, the spray mass has the same shape and extent over each of the light-emitting diode chips.

The arrangement of presorted light-emitting diode chips on an artificial wafer makes it possible, in particular color-homogeneous

Light-emitting diode components whose color distribution is restricted by the presorting to produce.

In various developments of the alternative method, the same injection molding materials and surface shapes can be used again, as described above. Also, the previously described methods for recessing the "wire bond pads" can be used.

In accordance with at least one embodiment of the method, the light-emitting diode chip comprises an active region in which the electromagnetic primary radiation, for example blue light, is generated during operation of the light-emitting diode chip. In which

LED chip remains a major surface of the

LED chips, through which a large part of the primary radiation leaves the LED chip, free of contact structures and current distribution paths. That is, this main surface, for example, a carrier for the epitaxial

deposited layers of the LED chip

is opposite, is free of, for example, a bonding pad and / or power distribution tracks for current expansion over the entire main surface. Rather, in this light-emitting diode chip, the current distribution below the

Main area and thus below a large part of

Radiation exit area. In this way, no light-absorbing structures are arranged on the first main surface and the efficiency of the LED chip is increased.

In this case, the light-emitting diode chip comprises at least one electrically conductive plated-through hole, in particular a multiplicity of electrically conductive plated-through holes, which penetrate the active region from the side facing away from the main surface of the light-emitting diode chip. For example, in this way the n-conducting side of the light-emitting diode chip can be connected in an electrically conductive manner. A contact surface, for example a bonding pad, for electrically connecting the n-side of the light-emitting diode chip can then be arranged laterally adjacent to the semiconductor body of the light-emitting diode chip.

In particular, it is possible that all

LED chips that are provided in the process with the spray mass are carried out in this way.

According to at least one embodiment of the method, the thickness of the spray mass at its thickest point is at most 100 ym. Preferably, the thickness of the spray mass at its thinnest point does not fall below 60 ym. In this way, it is possible to cover the LED chip with a sufficiently thick layer of conversion agents, so that the "blue piping" described above does not occur. On the other hand, with such a thin layer too much heating of the

Conversion and thus the above-described "stock shift" can be avoided. After wrapping the light-emitting diode chips, these are separated by sawing the artificial wafer. The so isolated chip is coated on all side flanks and the surface with converter-filled potting material, resulting in a significant reduction of inhomogeneities of the color location, especially at the edges.

In alternative embodiments of the method, the individual light-emitting diode chips are separated by water jet cutting, lasers or punching.

In a particularly advantageous embodiment of the method, the light-emitting diode chips are separated by means of a specially designed saw, which generates a structure on the side edges, along the parting line. This achieves a further improvement of the color homogeneity over the emission angle.

Embodiments will be explained with reference to the figures.

Show it:

FIG. 1A shows an exemplary embodiment of an intermediate product which is produced according to an embodiment of the method according to the invention.

FIG. 1B shows an alternative embodiment of the invention

Intermediate of Figure la.

Figure 2A third embodiment of a

Intermediate, which after a Embodiment of the method according to the invention is made.

FIG. 2B shows an alternative embodiment of the invention

Intermediate product of Figure 2a.

FIG. 3 shows a schematic sectional view of a light-emitting diode component produced by means of a method described here.

In the embodiments are the same or the same

acting components each provided with the same reference characters. The intermediate product in FIG. 1A includes a chip carrier 1, which has light-emitting diode chips 3 and with a

Layer of spray mass 2 is covered. The chip carrier 1 with applied light-emitting diode chips 3 was introduced into the cavity of an injection mold and by driving a

Spray mass 2, which is mixed with a conversion agent, uniformly formed with a layer

Surrounded sprayed 2. The cavity is so

shaped so that a smooth, flat surface 5a is formed. Subsequently, the light-emitting diode chips 3 on the

Chip carrier 1 separated by sawing along a parting line 4.

In FIG. 1B, the intermediate product of one embodiment of the method according to the invention has a chip carrier 1 with applied light-emitting diode chips 3, which is covered by a layer of sprayed material 2. For this purpose, the chip carrier 1 was introduced with the applied light-emitting diode chips 3 in a cavity of an injection mold and by driving a spray mass 2, the conversion agent are attached, uniformly surrounded with a layer of spray mass 2. The cavity of the injection mold is designed so that a structured

Surface 5b is created. The carried by the chip carrier 1

Light-emitting diode chips 3 are subsequently separated by sawing along a dividing line 4.

The intermediate product in FIG. 2A includes chip carrier 1, with light-emitting diode chips 3 applied thereto, which are produced by

Spray mass 2 are surrounded. According to the proposed

Procedure were the individual and, for example, after

Color location pre-sorted chip carrier 1, arranged thereon with light-emitting diode chips 3, arranged to form an artificial wafer and then introduced into a cavity of an injection mold. Then, a spray mass 2 was driven in such a way that the chip carriers 1, each having an LED 3, are surrounded by a uniform layer of spray mass 2. The spray mass are conversion agents

attached. The cavity of the injection mold is in this case shaped such that a smooth, flat surface 5a is formed. The light-emitting diode chips 3 each applied to a chip carrier 1 are singulated by means of sawing along a parting line 4. The intermediate product shown in Figure 2B again

Chip carrier 1 with applied light-emitting diode chips 3, which are enveloped by a spray mass. For this purpose, the

arranged individual chip carrier 1 to an artificial wafer and introduced into a cavity of an injection mold. By

Driving a spray mass 2 was the arrangement

uniformly surrounded by a layer of spray mass 2. The cavity of the injection mold is designed such that a structured surface 5b is formed. The individual, up the chip carriers 1 arranged, light-emitting diode chips 3 are separated by sawing along a parting line 4.

In alternative forms, the intermediates in Figures 2A and 2B can also be singulated by water cutting, punching or laser separation.

FIG. 3 shows a schematic sectional view of a light-emitting diode component produced by means of a method described here. The light-emitting diode component has a chip carrier 1. The chip carrier 1 can, for example, with an electrically conductive material such as germanium,

Silicon or copper may be formed. At the top of the chip carrier 1, the LED chip 3 is arranged. In the present case, the light-emitting diode chip 3 consists, for example, of an epitaxially grown semiconductor body. Of the

LED chip 3 can be free from a growth substrate. That is, for example, the chip carrier 1

Originally opposite growth substrate is removed and the LED chip 3 consists of epitaxial

grown layers.

The light-emitting diode chip 3 comprises an active region 30. In the active region 30, primary radiation is generated during operation of the light-emitting diode chip 3. A large part of the primary radiation leaves the LED chip through the main surface 31. However, part of the primary radiation also exits through the lateral surfaces of the chip extending transversely to the main surface 31. Through the active region 30 extends

at least one electrical feedthrough 32, the

in this case, for example, the n-type region of

Semiconductor body of the LED chip 3 connects. In the present case, the contacting is carried out laterally on the light-emitting diode chip 3, and a contact surface 33 is exposed there. Above the contact surface 33, the spray mass 2, which otherwise surrounds the light-emitting diode chip 3, is removed. To the

Contact surfaces 33, for example, a wire contacting of the LED chip 3 done, for example, in the contact surface 33 is then a so-called bond pad. The invention is not by the description based on the

Embodiments limited to these. Rather, the invention encompasses every new feature as well as every combination of features, which in particular includes any combination of features in the patent claims, even if this feature or combination itself is not explicitly described in the claims

Claims or embodiments is given.

This patent application claims the priority of German Patent Application 102011102590.5, the disclosure of which is hereby incorporated by reference.

Claims

claims

1. A method for simultaneously producing a plurality of similar light emitting diode components, each having at least one light emitting diode chip and a

Conversion element, which at least a part of one of the at least one light-emitting diode chip (3) emitted

Wavelength-converted electromagnetic radiation, with the steps:

- Arrange wavelength pre-sorted light-emitting diode chip (3) to an artificial wafer

- introducing the wafer into a cavity of an injection mold

- Driving a spray mass (2), which with

Conversion agent is added to the cavity, so that the light-emitting diode chips (3) are surrounded with a uniform layer of spray mass,

Removing the injection mold,

- Separating the light emitting diode devices on the wafer.

2. A method for simultaneously producing a plurality of similar light-emitting diode components, each having at least one light-emitting diode chip and a

Conversion means, which at least a part of one of the at least one light-emitting diode chip emitted

Electromagnetic primary radiation wavelength-converted, with the steps:

- Providing a wafer with it applied

Light-emitting diode chips (3),

- introducing the wafer into a cavity of an injection mold, - driving a spray mass (2), which with

Conversion agent is added to the cavity, leaving the light-emitting diode chips with a uniform layer

Surrounded by spray mass, - Remove the mold

- Separating the light-emitting diode components on the wafer.

3. The method according to claim 1 or 2,

wherein at least one of the light-emitting diode chips (3) comprises an active region (30), in which in the operation of the

Light-emitting diode chips (3) the electromagnetic

Primary radiation is generated, wherein

a main surface (31) of the light-emitting diode chip (3) is free of contact structures and current distribution paths, and

- The light-emitting diode chip (3) at least one electrically

conductive via (32) which penetrates the active region (30) from the main surface (31) of the LED chip (3) facing away from side.

4. Method according to one of the preceding claims,

wherein the thickness of the spray mass at its thickest point is at most 100 ym.

5. Method according to one of the preceding claims,

wherein the surface of the cover by injection molding compound (2) gives a smooth, flat surface (5a).

6. The method according to any one of the preceding claims,

wherein the surface (5b) of the cover by injection molding compound (2) has a structure.

7. The method according to any one of the preceding claims,

in which the light-emitting diode chips (3) have electrical contact surfaces (33).

8. Method according to the preceding claim, in which on the electrical contact surfaces (33) mounted spray mass (2) is removed by means of laser radiation.

9. Method according to one of the preceding claims,

in the electrical contact surfaces (33) of the LED chip (3) are covered before introduction into the cavity and exposed again before singulating.

10. Method according to the preceding claim,

in which the covering of the electrical contact surfaces (33) of the light-emitting diode chip (3) takes place by means of foils which act on the front-side surface of the light-emitting diode chip

be applied.

11. The method according to any one of the preceding claims,

in which the covering of the electrical contact surfaces (33) of the light-emitting diode chip (3) takes place through a front-side inner wall of the injection mold.

12. The method according to any one of the preceding claims,

in which the covering of the electrical contact surfaces (33) of the light-emitting diode chip (3) by a photoactive layer

he follows .

13. The method according to any one of the preceding claims,

in which the separation of the light-emitting diode light sources

or light-emitting diode chips (3) by sawing or by water jet cutting or by laser separation or punching done.