WO2017085063A1

WO2017085063A1 - Led filaments, method for producing led filaments, and retrofitted lamp comprising an led filament

Info

Publication number: WO2017085063A1
Application number: PCT/EP2016/077743
Authority: WO
Inventors: Thomas Schlereth; Tamas Lamfalusi; Ivar TÅNGRING
Original assignee: Osram Opto Semiconductors Gmbh
Priority date: 2015-11-19
Filing date: 2016-11-15
Publication date: 2017-05-26
Also published as: DE102015120085A1

Abstract

Disclosed is an LED filament (14) comprising a substrate element (2) having a reflective first main surface (5) to which a plurality of LED chips (4) is applied in a row along a main direction of extension (3), and a first electric contact point (10) in a first end region (15) on the first main surface (5) of the substrate element (2). The LED chips (4) are electrically connected in series. Also disclosed are another LED filament, two methods for producing an LED filament, and a retrofitted lamp comprising an LED filament.

Description

description

LED filaments, process for producing LED filaments and retrofit lamp with LED filament

There are LED filaments, processes for the production of LED filaments and a retrofit lamp with a corresponding LED filament specified. LED filaments are, for example, the following

Publications known: US 2014/369036 AI, WO 2015/000288 AI.

An object of the present invention is to provide an LED filament with improved heat dissipation. Another task is to provide a simplified procedure for

Production of a LED filament with improved cooling and a retrofit lamp with a LED filament with

indicate improved heat dissipation. These tasks are performed by an LED filament with the

Features of the independent claims 1 and 4, by a method with the steps of claims 14 and 16 and by a retrofit lamp with the features of claim 19 solved.

Advantageous embodiments and further developments of the LED filament, the method for producing a LED filament and the retrofit lamp are the subject of each

dependent claims.

In one embodiment, an LED filament is included

Carrier element with a reflective first major surface. On the reflective first main surface of the Carrier element is applied a plurality of LED chips in a row along a main extension direction of the support element. The reflective first major surface is

preferably formed specular reflective. The

reflective first major surface contributes to that

Filament in operation gives the impression of a filament to an external observer.

The LED chips have an epitaxially grown

Semiconductor layer sequence with an active zone, which in operation electromagnetic radiation of a first

Wavelength range generated. The electromagnetic radiation generated during operation of the LED chip emits the LED chip from a light exit surface.

The LED chips may, for example, be so-called volume emitters. A volume-emitting LED chip has a substrate on which the semiconductor layer sequence has usually been grown epitaxially. The substrate may for example comprise one of the following materials or consist of one of the following materials: sapphire,

Silicon carbide. Volume-emitting LED chips usually emit the radiation generated in the active zone not only via the light exit surface, but also via their side surfaces.

Furthermore, the LED chips can also be thin-film LED chips. Thin-film LED chips have an epitaxially grown semiconductor layer sequence which is applied to a different carrier than the growth substrate for the semiconductor layer sequence. Particularly preferred is between the semiconductor layer sequence and the carrier a

Mirror layer arranged to the radiation of the active zone to Light exit surface directs. Thin film LED chips typically do not emit the electromagnetic radiation generated in operation in the active zone beyond the wearer's side surfaces, but essentially do so

Lambertian radiation characteristic.

According to one embodiment of the LED filament, the LED chips of a row are electrically connected to one another in series and / or in parallel. The LED chips can by means of

Bonding wires, tapes or even lithographically contacted electrically. For example, the LED chips are electrically connected in series with one another by front-side bonding wires. According to a further embodiment of the LED filament, the carrier element has a first electrical contact point on a first end region of the first main surface.

For example, the front side of the directly adjacent LED chip is electrically conductively connected to the contact point with a bonding wire. In this case, the first contact point is preferably insulated electrically against the carrier element.

According to a further embodiment of the LED filament, the LED chips are embedded in a conversion element, the electromagnetic radiation of the first wavelength range in electromagnetic radiation of a second

Wavelength range, that of the first

Wavelength range is different. Alternatively, it is also possible for the LED chips to be embedded in a protective layer which is free of wavelength-converting properties and serves only for the protection of the LED chips and / or the mechanical stabilization of the LED filament. Particularly preferably, the conversion element converts the

Radiation of the LED chips only partially around, leaving a

certain proportion of the radiation of the LED chips that

Conversion element passes unconverted. In this way, the LED filament emits mixed-color radiation consisting of converted and unconverted radiation

composed. More preferably, the LED filament emits mixed colored radiation having a color location in the white area of the CIE standard color chart.

Volume emitting LED chips are preferably in one

embedded common conversion element that the

Side surfaces and also the light exit surfaces of the LED chips completely enveloped. Particularly preferably, the conversion element fills the areas between the LED chips completely. Such a conversion element advantageously contributes to the mechanical stabilization of the LED filament. For example, the conversion element comprises a resin, in which phosphor particles are introduced, which are the

Conversion element the wavelength-converting

Lends properties. The resin may be a silicone or an epoxy or a mixture of these materials.

For example, one of the following materials is suitable for the phosphor particles: rare earth doped garnets, rare earth doped alkaline earth sulfides, rare earth doped thiogallates, rare earth doped aluminates, rare earth doped silicates, rare earth doped orthosilicates, rare earths doped chlorosilicates, doped with rare earths Alkaline earth silicon nitrides doped with rare earths

Oxynitrides, rare earth doped aluminum oxynitrides, rare earth doped silicon nitrides, rare earth doped sialons.

Is it the LED chips of the LED filament around

Thin-film LED chips, they may each have a separate conversion layer as a conversion element, which is placed on the light exit surface of each LED chip.

According to a further embodiment of the LED filament, a further multiplicity of LED chips are applied in a row along the main extension direction of the carrier element on the first main surface of the carrier element. With others

Words are on the first main surface of the support member two juxtaposed rows of LED chips

applied. The two rows are particularly preferably arranged parallel to one another along the main extension direction.

If the carrier element has two rows of LED chips arranged next to one another, a second electrical contact point is particularly preferably arranged on the first end region of the first main surface. In other words, the first electrical contact point and the second are

electrical contact point on the same end of the

Support element. Preferably, the opposite is

End region of the carrier element in this case free from a

Contact point. Preferably, the second electrical contact point is also electrically insulated from the carrier element.

Particularly preferred in this embodiment, two directly adjacent rows of LED chips are completely serial interconnected with each other. In this case, the external electrical contacting of the LED filament particularly preferably takes place via the first electrical contact point and the second electrical contact point on the first end region.

The two rows of LED chips can in turn be embedded in a common conversion element. Alternatively, it is also possible that every LED chip on its

Light exit surface is provided with a separate conversion layer.

According to another embodiment of the LED filament, on a second major surface of the support member facing the first major surface, another plurality of LED chips are arranged in a row along the

Applied main direction. In other words, in this embodiment, both main surfaces of the carrier element are each equipped with at least one row of LED chips along the main extension direction. Such an LED filament advantageously has two

opposite main emission directions.

Also the LED chips on the second main face of the

Carrier element can be embedded in a common conversion element. Alternatively, it is again possible that each LED chip is provided on its light exit surface with a separate conversion layer.

Indicates the LED filament on both major surfaces of the

Carrier element in each case at least one row of LED chips, so in a second end region of the first

Main surface of the support member particularly preferably a second electrical contact point arranged, wherein the second end portion of the first main surface opposite to the first end portion. On one end region of the second main surface of the carrier element, a third electrical contact point is preferably applied. Here, the end region of the first main surface on which the second contact surface

is arranged, and the end portion of the second main surface, on which the third contact point is arranged, preferably arranged at a common end of the support element. In other words, the second electrical contact point and the first electrical contact point are arranged at a common end of the carrier element.

Particularly preferably, the second electrical contact point and the third electrical contact point are further provided by an electrically conductive element perpendicular to the

Main extension direction of the support member extends, electrically connected to each other. For example, the electrically conductive element runs along one

Side surface of the support element. The electrically conductive element may be, for example, an electrodeposited metallic layer. Alternatively, the electrically conductive element can also be produced by a dipping process.

Particularly preferably, the first electrical

Contact point and the third electrical contact point and the electrically conductive element embedded in a potting. The potting can be clear or reflective. For example, the potting compound comprises a silicone or an epoxide or a mixture of these two materials. If the potting formed reflective, so are preferred in introduced the otherwise clear potting titanium oxide particles.

According to a further embodiment of the LED filament this may have a clear envelope as the outermost layer. For example, this clear envelope silicone or is formed of silicone. The clear coating serves both to protect the components of the LED filament and the mechanical stabilization of the LED filament.

According to a further embodiment of the LED filament, the carrier element is provided with an electrical

Contacting layer is covered, which is separated by an electrically insulating layer of the support element.

For example, the electrically insulating layer is applied in direct contact with the carrier element and the electrical contacting layer in direct contact with the electrically insulating layer. The electrically insulating layer and the electrical

The contacting layer preferably extends from the first main surface of the carrier element to the second main surface of the carrier element via a side surface of the carrier element. Particularly preferred here are the first main surface of the carrier element, the second main surface of the carrier element and the side surface of the carrier element continuous with the electrically insulating layer and the electrical

Contacting layer covered. Such an arrangement makes it possible to equip each of the first main surface of the carrier element and the second main surface of the carrier element with at least one row of LED chips and all LED chips serially with the aid of electrical

Contacting contact layer. With the help of electrical contacting layer and the electrical

Insulating layer is an electrical contact via the front sides of the LED chips, for example by

Wire bonding, superfluous.

Another LED filament also has a multiplicity of LED chips which emit electromagnetic radiation of a first wavelength range from a light exit surface and are arranged in a row along a main direction of extent. Furthermore, the LED filament comprises a mechanically stabilizing material, which fills areas between the LED chips up to the light exit surfaces of the LED chips, so that the light exit surfaces of the LED chips and the mechanically stabilizing material form a first plane surface. The mechanically stabilizing material may be clear or transparent. For example, the mechanically stabilizing material is a resin, such as a silicone or an epoxy. Titanium oxide particles which impart reflective properties to the mechanically stabilizing material can be introduced into the silicone or the epoxide. Particularly preferably, the two end regions of the LED filament are each formed by the mechanically stabilizing material. Preferably, the LED filament is a mechanical

stabilizing material, free of one

Carrying member. For example, the LED filament is mechanically stabilized solely by the mechanically stabilizing material.

According to one embodiment of this LED filament, a first electrical contact point is arranged on a first end region of the first planar surface and a second electrical contact point electrical contact point arranged on a second end region of the first planar surface, wherein the first end region opposite to the second end region.

Also this LED filament can be a conversion element

have, the electromagnetic radiation of the first

Wavelength range of the LED chips converts into electromagnetic radiation of a second wavelength range. The conversion element is preferably arranged on the first planar surface. For example, this extends

Conversion element along all the LED chips over the entire first plane surface. Alternatively, each individual LED chip with a conversion layer as

Be covered conversion element. Alternatively, it is possible for a protective layer to be applied to the first plane surface

is applied, which serves to protect the LED chips and / or the mechanical stabilization of the LED filament.

According to one embodiment of the LED filament, a carrier element having a first reflective main surface is applied on a second planar surface of the LED chip composite, which is opposite the first planar surface. In this case, the reflective main surface particularly preferably points to the LED chip interconnection.

According to a further embodiment of the LED filament, on a second major surface of the carrier element, which is opposite the first main surface, a further plurality of LED chips in a row along the

Main extension direction arranged. Particularly preferably, these LED chips are also arranged in an LED chip composite, in which the LED chips are connected to a mechanically stabilizing material, wherein the mechanically stabilizing material fills the areas between the LED chips preferably up to the light exit surfaces of the LED chips.

According to a particularly preferred embodiment, the carrier element comprises a metal substrate or is made of a

Metal substrate formed. Particularly preferably, the first reflecting main surface of the carrier element is formed from silver or comprises silver. For example, that is

Support member formed of an aluminum substrate, which is provided on both major surfaces with a silver layer. It is also possible to use a pure aluminum substrate as

Carrier element to use. Such a carrier element has an improved heat dissipation due to

Aluminum substrate and a very high reflectivity due to the silver layer.

According to one embodiment of the LED filament, the support element comprises glass or ceramic or is made of glass or

Ceramics formed.

The reflectivity of the main reflective surface of the

Carrier element is particularly preferably at least 95%. Particularly preferably, the reflectivity of the first main surface or the second main surface of the carrier element is 98%. In particular, particularly preferred is the above

described silver layer such values for the

Reflectivity on.

An idea of the present application is to

To use carrier element for the LED filament with a particularly good thermal conductivity and very well reflecting major surfaces. Such a carrier element is given for example by a silver-coated aluminum substrate. According to a further embodiment, the carrier element comprises cooling ribs. For example, this indicates

Carrier element has a base body with a rod-shaped

Geometry, from the side surfaces, fingers as

Extend cooling fins. According to one embodiment, the fingers extend laterally out of the main body along the main extension direction of the carrier element at regular intervals.

Furthermore, it is also possible that the cooling ribs are formed as fingers, which are arranged in bundles, wherein the fingers of a bundle radiate from a common base point away.

The cooling fins have the advantage that they

Further improve heat dissipation from the LED filament.

In particular, radially arranged fingers have a particularly good heat dissipation.

The cooling fins are preferably made of the same material as the main body. In particular, the surface of the cooling fins is preferably also designed to be highly reflective. This also makes the cooling fins visually attractive.

According to a further embodiment, the LED filament is formed twisted along a longitudinal axis. The longitudinal axis in this case particularly preferably runs along the

Main extension direction of the support element. This improves the radiation behavior of the LED filament. For example, the carrier element is rotated along the longitudinal axis in such a way that the first main surface and the second main surface of the carrier element rotate helically along the longitudinal axis are. In other words, the rotation preferably takes place about the longitudinal axis.

In a method for producing at least one LED filament is first a carrier element with a

provided reflective first major surface. A plurality of LED chips are then applied to the first major surface of the carrier in a row along a main direction of extent of the carrier element.

At least one first electrical contact point is applied in one end region of the carrier element. Finally, the LED chips, particularly preferably in series, are electrically connected, for example by wire bonding.

The electrical contact point can, for example, by

Gluing a contact foil are applied. The

Contact foil comprises, for example, a layer composite of a dielectric layer, a copper layer and a gold layer. Furthermore, the electrical contact point by a paste printing, such as screen printing or

Inkjet printing, are generated.

This method is preferred as a batch process

performed in which several LED filaments are produced. Here, a plurality of carrier elements is provided in a carrier, wherein on each carrier element at least one row is applied with LED chips. By separating the carrier eventually creates a variety of LED filaments. The separation can be done for example by means of sawing or punching. A batch process offers the advantage of being able to generate several components in parallel. For example, in such a batch process directly adjacent rows on the carrier may be connected in series in parallel and the carrier may be singulated such that each LED filament is at least two on the first

Has main surface of each support member arranged rows of LED chips.

According to a further embodiment of the method, a further plurality of LED chips are applied in a row along the main direction of extent to a second reflective main surface of the carrier element, wherein the second

Main surface of the first major surface opposite.

In accordance with a further embodiment of the method, the LED chips are embedded in a wavelength-converting layer, which converts electromagnetic radiation of the first wavelength range, which is emitted by a light exit surface of the LED chips, into electromagnetic radiation of a second wavelength range. The wavelength-converting layer can be produced for example by means of dispensing, molding or die-casting.

Furthermore, it is also possible that as

wavelength converting layer is laminated on a converter film. From the wavelength-converting

Layer are made by separating conversion elements

educated .

In a further method for producing at least one LED filament, a subcarrier is provided on which a plurality of LED chips in a row along a

Main extension direction is applied. The LED chips are then embedded in a mechanically stabilizing material. This is particularly preferred mechanically stabilizing material filled up to the light exit surfaces of the LED chips. For example, for this purpose, a film may be applied to the light exit surfaces of the LED chips prior to the application of the mechanically stabilizing material, so that the areas between the LED chips are sealed by the auxiliary carrier on one side and by the film on the other side. The mechanical

stabilizing material is then preferably introduced by means of spraying in the areas between the LED chips (Foil Assisted Molding). Before further processing, the film is removed again.

After application of the mechanically stabilizing material, the auxiliary carrier is removed again. Then at least one electrical contact point is applied in an edge region of the LED chip composite. Finally, the LED chips are connected in series with each other, for example by means of

Wire bonding. This method can also be carried out in a batch process in which a plurality of rows of LED chips are applied to the subcarrier and the LED chip group is singulated, so that a multiplicity of LED filaments is formed. The resulting composite of interconnected LED chips, which are mechanically stable connected by the mechanically stabilizing material, can already be used as an LED filament. Furthermore, it is also possible for a carrier element or carrier having a plurality of carrier elements to be applied to the LED chip composite, wherein the carrier element or the carrier has a first reflective main area. The LED Chip composite is in this case particularly preferably on the first reflective main surface of the support element or the

Carrier applied. Furthermore, it is possible in this method that a further LED chip composite on a second reflective main surface of the support element or the

Support opposite the first major surface,

is applied.

If the carrier element has at least one LED chip composite on its two main surfaces, the opposing contact points at one end of the

Carrier element with an electrically conductive element

be electrically connected, so that the LED chips are connected in series on the first main surface of the support member with the LED chips on the second main surface of the support member.

The LED filaments described herein are particularly suitable for use as a light source in a retrofit lamp. Particularly preferably, the LED filaments in

Operate the appearance of a filament of a conventional light bulb.

The retrofit lamp preferably comprises a piston which has the shape of the bulb of an incandescent lamp. The piston is usually mounted in a socket that is threaded

has, which corresponds to that of a light bulb.

According to a preferred embodiment of the retrofit lamp, the LED filament is connected with its carrier element to the base heat-conducting. This improves the heat dissipation of the LED filament during operation of the retrofit lamp. According to a preferred embodiment of the retrofit lamp, the piston is filled with a gas, for example with air or helium, in order to further improve the heat removal from the LED filament.

Further advantageous embodiments and developments of the invention will become apparent from the embodiments described below in conjunction with the figures. A first exemplary embodiment of a method for producing an LED filament will be described with reference to the schematic representations of FIGS. 1 to 9.

FIG. 10 shows a schematic sectional representation of an LED filament according to one exemplary embodiment.

FIG. 11 shows a schematic representation of a

Retrofit lamp with LED filaments according to the

Embodiment of Figure 10.

Reference to the schematic representations of Figures 12 to 20, a further embodiment of a method for producing an LED filament is explained in detail. FIG. 21 shows a schematic sectional illustration of an LED filament according to a further exemplary embodiment.

FIG. 22 schematically shows an exemplary embodiment of a retrofit lamp with LED filaments in accordance with FIG

Embodiment of Figure 21.

With reference to the schematic sectional views of Figures 23 to 30 is another embodiment of a method for producing an LED filament described in more detail. FIG. 29 shows a schematic sectional illustration of a finished LED filament. A further method for producing an LED filament will be described in more detail with reference to the schematic sectional views of FIGS. 31 to 42.

FIG. 42 schematically shows a finished LED filament according to a further exemplary embodiment.

FIG. 43 shows schematically another embodiment of a retrofit lamp with an LED filament in accordance with FIG

Embodiment of Figure 42.

FIG. 44 shows a schematic plan view of a carrier with a multiplicity of carrier elements according to FIG

Embodiment. A further exemplary embodiment of a method for producing LED filaments will be described with reference to the schematic representations of FIGS. 45 to 52.

Figures 53 and 54 show schematic representations of the finished LED filament.

A further exemplary embodiment of a method for producing LED filaments will be described with reference to the schematic representations of FIGS. 55 to 58.

Figures 59 to 61 show schematic representations of the finished LED filament. Figure 62 shows a schematic plan view of a carrier with a plurality of carrier elements according to a further embodiment. Figures 63 and 64 show schematic representations of an LED filament according to another embodiment.

A further embodiment of an LED filament will be described with reference to the schematic representations of FIGS. 65 to 67.

The same, similar or equivalent elements are provided in the figures with the same reference numerals. The figures and the proportions of the elements shown in the figures with each other are not to scale

consider. Rather, individual elements, in particular layer thicknesses, can be shown exaggeratedly large for better representability and / or better understanding. In the method according to the embodiment of Figures 1 to 9, first a carrier 1 with a plurality of

Carrier elements 2 provided (schematic plan view of Figure 2). Along a main extension direction 3 of each carrier element 2, a multiplicity of LED chips 4 are applied in a row to a first highly reflective main surface 5 of the carrier 1.

The LED chips 4 are in the present case

Volume emitter with a sapphire substrate 6, on the one

Semiconductor layer sequence 7 is epitaxially grown with an active zone. The active zone generates during operation

electromagnetic radiation of a first

Wavelength range, preferably blue light. In the present case, the carrier 1 has an aluminum substrate which has a highly reflective surface on both main surfaces

Silver layer is provided (not shown).

In a further step, as shown schematically in FIGS. 3 and 4, a first electrical contact layer 8 and a second electrical contact layer 9 are applied to edge regions of the carrier elements 2. The first

electrical contact layer 8 forms after separation of the

Carrier elements 2 each have a first electrical contact point 10 and the second electrical contact layer 9, a second electrical contact point 11 from. The electrical

Contact points 10, 11 are electrically insulated from the carrier element 2 by a dielectric layer.

In a next step, the LED chips 4 of a row are electrically connected in series along the main extension direction 3 of a carrier element 2, in the present case by means of

Bonding wires 12. Furthermore, the two LED chips 4, each directly adjacent to the contact layer 8, 9

are arranged, also electrically connected to a respective bonding wire 12 with the electrical contact layer 8, 9 (Figures 5 and 6).

Finally, a wavelength-converting layer 13 is applied by compression molding over the LED chips 4 (FIGS. 7 and 8). The wavelength-converting layer 13 is formed, for example, from a resin such as silicone or epoxy, are incorporated in the phosphor particles. In a next step, the carrier 1 is separated, so that a multiplicity of individual LED filaments 14 are produced (FIG. 9). FIG. 10 shows a schematic sectional illustration of an LED filament 14, as can be produced by the method according to FIGS. 1 to 9.

The LED filament 14 according to the exemplary embodiment of FIG. 10 has a carrier element 2 with a highly reflective first main surface 5, on which a multiplicity of LED chips 4 are applied in a row along a main extension direction 3 of the carrier element. The LED chips 4 are

front side by bonding wires 12 electrically serially

connected. On a first end portion 15 of the first

Main surface 5 is here a first electrical

Pad 10 is applied, which is electrically connected by means of a bonding wire 12 with the directly adjacent LED chip 4. On a second end portion 16 of the first main surface 5, which is opposite to the first end portion 15, a second contact point 11 is applied, which is also electrically connected to a bonding wire 12 with the directly adjacent LED chip 4. The LED chips 4 of the LED filament 14 according to the

Embodiment of Figure 10 are embedded in a common conversion element 17, the radiation of the LED chips 4 from the first wavelength range partially in

Radiation of a second wavelength range converts.

The first wavelength range preferably consists of blue

Light and the second wavelength range of yellow light, so that the LED filament 14 particularly preferably emits white light. Figure 11 shows a schematic representation of a retrofit lamp with a plurality of LED filaments 14 according to the

Embodiment of Figure 9 as a light source. The retrofit lamp preferably has four LED filaments 14.

The retrofit lamp in this case comprises a piston 18, which has the shape of a bulb of a light bulb. The piston 18 is fixed in a socket 19 with a thread corresponding to the thread of an incandescent lamp. The LED filaments 14 are mounted upright in the base 19. Here, the carrier element 2 of the LED filaments 14 is thermally conductively connected to the base 19.

For this purpose, first an LED filament 14, as it

is shown for example in Figure 9, with a

Heat sink or a printed circuit board (PCB) 20

soldered together. The LED filament 14 on the PCB 20 is then inserted into the base 19 of the retrofit lamp. The LED filaments 14 according to FIG. 9 radiate in this case

Essentially only after one side. For this reason, the LED filaments 14 are positioned in the bulb 18 of the retrofit lamp such that the main radiating surfaces of the LED filaments 14 face outward. Furthermore, the

Contact points 9 of the LED filaments 14 facing away from the base 19, electrically contacted with the corresponding contact point 9 of the directly adjacent LED filament 14, for example by means of a bonding wire 12. In the method according to the embodiment of Figures 12 to 20 are on the first major surface 5 each

Carrier element 2 of the carrier 1 more, preferably two,

Rows of LED chips 4 set. The LED chips 4 are here each aligned in rows along a main extension direction 3 of the support member 2 (Figures 12 and 13).

Finally, a structured contact layer 21 is applied to edge regions of the carrier 1, from which later by separation of the carrier 1 electrically conductive

Contact points 8, 9 arise on each support element 2

(Figures 14 and 15). In a next step, directly adjacent rows of LED chips 4 are connected in series, for example by bonding wires 12 (FIGS. 16 and 17).

Then the LED chips 4 in a common

Wavelength-converting layer 13 embedded (Figures 18 and 19). Finally, the LED filaments 14 are singulated (Figure 20).

Figure 21 shows a schematic plan view of a

Embodiment of a finished LED filament 14, as it can be produced by the method according to the embodiment of Figures 12 to 20. In this LED filament 14 are different from the LED filament 14 according to the

Embodiment of Figure 10 two mutually parallel rows of LED chips 4 along a

Main extension direction 3 of the support member 2 on a highly reflective first major surface 5 of the support member 2 is arranged. The LED chips 4 of the LED filament 14 are connected in series by bonding wires 12. In a first end region 15 of the first main surface 5 of the carrier element 2 are two electrically conductive contact points 10, 11th

applied, which are each electrically connected to the directly adjacent LED chip 4 with a bonding wire 12. The second end region 16 of the first main surface 5, which is opposite the first end region 15, is free of an electrical contact point. FIG. 22 shows a schematic representation of a retrofit lamp with a plurality, preferably four, LED filaments 14, as already described with reference to FIG. These LED filaments 14 are for insertion into the

Retrofit lamp with a heat sink or a PCB 20 soldered and arranged in the piston 18 of the retrofit lamp that they radiate outward. In the method according to the embodiment of the figures

23 to 30, first the steps are carried out as already described with reference to FIGS. 1 to 8

(Figures 23 to 26). Finally, the process steps of FIGS. 1 to 8 and FIGS. 23 to 26 are repeated on a second main surface 22 of the carrier 1, the second main surface 22 being opposite the first main surface 5. The result is a carrier 1, in which each carrier element 2 is provided with a series of serially interconnected LED chips 4 on a first main surface 5 and a second row of LED chips 4, which are also connected in series (Figure 27). The LED chips 4 on the first main surface 5 are in this case compared to the LED chips 4 on the second

Main surface 22 anti-parallel with each other electrically

interconnected.

Finally, a second wavelength-converting

Layer 13 on the first main surface 5 of the carrier 1 and a third contact layer 23 on the second main surface 22 of the carrier 1, which are arranged at a common end of the carrier 1, electrically conductively connected to an electrically conductive element 24. The electrically conductive element

24 runs perpendicular to the main extension direction 3 of the LED filament. In the electrically conductive element 24th it may, for example, be an electrodeposited layer.

Then the LED filaments 14 are separated by sawing

(not shown) .

In a next step, the second contact point 11, a third contact point 25 and the electrically conductive element 24 are embedded in a common encapsulation 26. The potting 26 is particularly preferably formed diffusely reflective. For example, the potting 26 is a silicone with titanium oxide particles.

Then the finished LED filament 14 is provided on its outer side with a clear envelope 27, for example made of silicone. The clear envelope 27 is on both the

Main surfaces of the conversion elements 17 and on the reflective potting 26 in the end region of the LED filament 14 are arranged (Figures 29 and 30).

In the method according to the exemplary embodiment of FIGS. 31 to 41, a plurality of LED chips 4 are placed on a subcarrier 28, for example a foil, in a row along a main extension direction 3 (FIG. 31). In a next step, a further film 30 is applied to light exit surfaces 29 of the LED chips 4, so that the areas between the individual LED chips 4 are sealed (FIG. 32). Then, as shown schematically in Figure 33, the LED chips 4 with a mechanical

stabilizing material 31 overmoulded (Foil Assisted

Molding). The mechanically stabilizing material 31 is particularly preferably highly reflective or else

transparent. It is in the mechanical stabilizing material 31, for example, a silicone or an epoxy. If the mechanically stabilizing material 31 is intended to be reflective, then it preferably contains

Titanium oxide particles.

In this case, the mechanically stabilizing material 31 completely fills the gaps between the LED chips 4 up to the light exit surfaces 29. The mechanically stabilizing material 31 and the light exit surfaces 29 of the LED chips 4 form a continuous first planar surface. In each case laterally of the outermost LED chip 4 also mechanically stabilizing material 31 is also arranged.

Finally, the film 30 and the subcarrier 28 are removed again and it is in the edge regions of the continuous first planar surface on the mechanically stabilizing

Material 31 a first electrical contact point 10 and a second electrical contact point 11 applied (Figure 34). In a next step, the LED chips 4 are electrically contacted on the front side by means of bonding wires 12, so that they are connected in series. Furthermore, in each case the outermost LED chip 4 is electrically conductively connected to the adjacent electrical contact point 10, 11 via a bonding wire 12 (FIG. 35). Already the device according to the

Embodiment of Figure 35 can be used as LED filament 14.

In a next step, which is shown schematically in FIG. 36, a conversion element 17 is applied to the first continuous plane surface. The conversion element 17 extends in this case starting from the first Contact point 10 over all light exit surfaces 29 of the LED chips 4 to the second contact point 11th

In a next step is on a second flat surface of the LED chip composite, the first flat surface

opposite, a support member 2 with a first

Main surface 5 is applied, which particularly preferably has a metal core, for example made of aluminum, which is provided on both sides with a silver layer (Figure 37).

In a next step, as schematically illustrated in FIG. 38, a further LED chip composite is applied to the second main surface 22 of the carrier element 2, the latter of which is applied to the second main surface 22 of the carrier element 2

Production has already been described with reference to Figures 31 to 36.

Finally, as shown schematically in FIG. 39, the second contact point 11 on the first LED chip composite and a third contact point 25 on the second LED chip group are replaced by an electrically conductive element 24

electrically connected to each other.

The method just described can also be carried out as a batch process. In a batch process, a plurality of LED filaments 14 are produced in a common bond, which is finally singulated.

As already described with reference to FIGS. 29 and 30, the second electrical contact point 11, the third one

electrical contact point 25 and the electrically conductive

Element 24 by a reflective encapsulation 26 wrapped. Finally, a further clear envelope 27 is applied over the entire filament (FIGS. 40 and 41). As shown schematically in FIG. 42, the resulting LED filament 14 is soldered to a heat sink or PCB 20 as shown in FIG.

Figure 43 shows a schematic representation of a

Retrofit lamp with an LED filament 14 on a PCB 20 according to the figure 42. Since the LED filament 14 in this case has two main emission directions, it is sufficient to use a single LED filament 14 as the light source. These

Retrofit lamp radiates in particular to all sides, wherein the soldered metal core of the support member 2 provides good heat dissipation. FIG. 44 shows a schematic plan view of a carrier

1 with a plurality of support elements 2. The support elements

2 have a rod-shaped base body 32 with a main extension direction 3 and a longitudinal axis L, which runs parallel to the main extension direction 3. Furthermore, each carrier element 2 has a multiplicity of cooling ribs 33, which extend laterally out of the main body 32. The cooling fins 33 are formed as fingers, wherein a plurality of fingers are always arranged in a bundle and

extending from a common base point P in different directions in space.

A schematic plan view of a single carrier element 2 shows, for example, FIG. 45, while FIG. 46 shows a side view of the carrier element 2 of FIG.

In the method according to the embodiment of Figures 45 to 52 is on the two opposite

End portions 15, 16 of the first main surface 5 of the Carrier element 2 according to the figure 45, a first contact point 10 and a second contact point 11 applied (Figures 47 and 48). Finally, a row of LED chips 4 is placed along the main extension direction 3 of the rod-shaped base body 32 of the support element 2 and by means of

Bonding wires 12 connected in series with each other and electrically connected to the first contact point 10 and the second contact point 11 (Figure 49).

The method as shown in FIGS. 47 to 49

is now repeated on the second major surface 22 of the support member 2 (Figure 50).

Finally, the LED chips 4 are embedded on the first main surface 5 of the carrier element 2 and on the second main surface 22 of the carrier element 2 in a common conversion element 17 (FIGS. 51, 52 and 53). The first electrical contact point 10 and the second electrical contact point 11 protrude laterally out of the conversion element 17.

FIG. 54 shows a schematic perspective illustration of a finished LED filament 14, as with the method according to the exemplary embodiment of FIGS. 45 to 53

can be produced.

The LED filament 14 according to the embodiment of FIG. 54 has a carrier element 2 with a rod-shaped one

Main body 32, on the first main surface 5 a

Row of LED chips 4 along a main extension direction 3 of the body 32 is applied to. On a second main surface 22 of the support element 2, the first Main surface 5 is opposite, is also a plurality of LED chips 4 in a row along a

Main extension direction 3 of the main body 32 is arranged. Laterally from the support member 2 extend fingers, which serve as cooling fins 33. The fingers are from the same

Material manufactured, as the main body 32. The fingers are further arranged in bundles, which have a common

Have base point 9 on a side surface of the base body 32.

The LED chips 4 of the LED filament 14 according to FIG. 54 are encased in a common conversion element 17, the radiation of the LED chips 4 from a first

Wavelength range partially converts radiation of a second wavelength range.

In the method according to the exemplary embodiment of FIGS. 55 to 58, initially again a carrier element 2

provided (Figure 55). In contrast to that

Carrier element 2, which has already been described with reference to Figure 45, the carrier element 2 according to Figure 55 in its main body 32 individual chip areas, which by

Bulges are separated, with the individual chip areas remain connected by webs.

As shown schematically in FIG. 56, an LED chip 4 is then applied to each chip area. The LED chips 4 are electrically connected in series with one another by bonding wires 12 and electrically conductively connected to contact points 10, 11 which are arranged on a first end region 15 of the carrier element 2 and on a second end region 16 of the carrier element 2. These steps will be on the second main surface 22 of the support member 2 is repeated, so that a plurality of LED chips 4 is applied to both main surfaces 5, 22. In a next step, the carrier element 2 is rotated along its longitudinal axis 1 (FIG. 57).

After that, the LED chips 4 are embedded in a conversion element 17 (FIG. 58).

Figures 59 to 61 show schematic representations of the LED filament 14, as can be prepared for example with the method according to Figures 55 to 58. The LED filament 14 has a carrier element 2, on the first main surface 5 and on the second main surface 22 of which a multiplicity of LED chips 14 are applied in a row along a main extension direction 3 of the carrier element 2. Laterally extend as fingers

formed cooling fins 33 from a rod-shaped base body 32 of the support element 2. The fingers are in bundles

arranged extending from a base point P in different spatial directions. Furthermore, the LED filament 14 has a conversion element 17 into which

all LED chips 4 are embedded. The

Conversion element 17 is cylindrical in this case and surrounds the rod-shaped base body 32 except for the

Side surfaces completely. Laterally out of the

Conversion element 17, the first electrical contact point 10 and the second electrical contact point 11 extend.

Figure 62 shows a schematic plan view of a carrier 1 with a plurality of support elements 2 according to a another embodiment. In contrast to the carrier element 2 according to FIG. 45, the carrier elements 2

Cooling ribs 33 which are formed as fingers and extend at regular intervals from a rod-shaped base body 32 of the support member 2 out. The cooling fins 33 are regularly spaced and extend perpendicular to a longitudinal axis L of the base body 32.

Figures 63 and 64 show schematic representations of an LED filament 14 with a support member 2 of the carrier 1 according to the embodiment of Figure 62. The LED filament 14 differs from the LED filament 4 according to the

Figures 59 to 61 in particular by the support member 2 and further in that the support member 2 is not rotated about its longitudinal axis L.

With reference to the schematic sectional views of Figures 65 to 67 is an LED filament 14 with an alternative

Contacting possible described. FIG. 66 shows detail A of FIG. 65 in a detail view, while FIG. 67 shows detail B from FIG. 65 in a detail view

Detail view represents. In the areas A and B, these are the end regions of the LED filament 14 according to FIG. 65.

The support member 2 of the LED filament 14 according to the

Embodiment of Figures 65 to 67 has a

electrical contacting layer 34 and an insulating layer 35, wherein the insulating layer 35 is applied in direct contact with the carrier element 2 and the electrical contacting layer 34 again in direct contact with the insulating layer 35. As shown in Figure 67, extend the insulating layer 35 and the electrical contacting layer 34 in this case over the

Side surface of the support member 2 at one of the ends of the support member 2. With the aid of the insulating layer 35 and the electrical contact layer 34, the LED chips 4, which are applied to the first main surface 5 of the support member 2 and the second major surface 22 of the support member 2 , all together in series. Furthermore, one can do without a bonding wire 12 in this embodiment.

The present application claims the priority of the German application DE 102015120085.6, whose

The disclosure is hereby incorporated by reference. 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.

Reference sign list

1 carrier

2 carrier element

3 main direction of extension

4 LED chip

5 first major area

6 Sapphire substrate

7 semiconductor layer sequence

8 first electrical contact layer

9 second electrical contact layer

10 first electrical contact point

11 second electrical contact point

12 bonding wire

13 wavelength-converting layer

14 LED filament

15 first end area

16 second end region

17 conversion element

18 pistons

19 sockets

20 PCBs

21 structured contact layer

22 second main area

23 third contact layer

24 electrically conductive element

25 third contact point

26 potting

27 serving

28 subcarriers

29 light exit surface

30 foil

31 mechanically stabilizing material 32 basic body

L longitudinal axis

33 cooling rib

P base point

34 electrical contacting layer

35 electrically insulating layer

Claims

claims

1. LED filament (14) with:

- A support member (2) having a reflective first major surface (5) on which a plurality of LED chips (4) in a row along a main extension direction (3) is applied, wherein the LED chips (4) serially and / or are electrically connected in parallel,

- A further plurality of LED chips (4) on a second major surface (22) of the support element (2), which is the first major surface (5) opposite, in a row along the main extension direction (3) is applied, and

a first electrical contact point (10) on a first end region (15) of the first main surface (5) of the

Carrier element (2), wherein

- on the first main surface (5) of the support element (2) in a second end region (16), which is opposite the first end region (15), a second electrical contact point (11) and on the second main surface (22) of the support element (2) in one end region, a third electrical contact point (25) is applied, and

- The second electrical contact point (11) and the third electrical contact point (25) by an electrically conductive element (24) which is perpendicular to the main extension direction (3), are electrically conductively connected to each other.

2. LED filament (14) according to the preceding claim, wherein

- The LED chips (4) emit electromagnetic radiation of a first wavelength range of a light exit surface (29), and

- The LED chips (4) in a conversion element (17)

are embedded, the electromagnetic radiation of the first Wavelength range into electromagnetic radiation of a second wavelength range converts.

3. LED filament (14) according to one of the above claims, wherein a further plurality of LED chips (4) in a row along the main extension direction (3) on the first main surface (5) of the carrier element (2) is applied, and

on the first end portion (5) has a second electrical

Contact point (11) is arranged.

4. LED filament (14) with:

- A plurality of LED chips (4), the electromagnetic radiation of a first wavelength range of a

Emitting light exit surface (29) and arranged in a row along a main extension direction (3),

- A mechanically stabilizing material (31), the

Areas between the LED chips (4) up to the

Light exit surfaces (29) of the LED chips (4) fills, so that the light exit surfaces (29) of the LED chips (4) and the mechanically stabilizing material (31) a first plane

Form surface, wherein the mechanically stabilizing material (31) is a silicone or an epoxy, in the

Titanium oxide particles are introduced,

- A first electrical contact point (10) which is arranged on a first end portion (15) of the first planar surface, and

- A second electrical contact point (11) which is arranged on a second end portion (16) of the first planar surface, wherein the first end portion (15) opposite the second end portion (16).

5. LED filament (14) according to the preceding claim, which is free of a carrier element.

6. LED filament (14) according to any one of claims 4 to 5, wherein

on the first planar surface, a conversion element (17) is arranged, which converts electromagnetic radiation of the first wavelength range into electromagnetic radiation of a second wavelength range.

7. LED filament (14) according to one of claims 4 to 6, wherein on a second planar surface of the LED chip composite, which is the first planar continuous surface opposite, a support element (2) having a first reflective

Main surface (5) is applied.

8. LED filament (14) according to any one of claims 4 to 7, wherein on a second major surface (22) of the carrier element (2) which is opposite the first main surface (5), a further plurality of LED chips (4 ) are arranged in a row along the main extension direction (3).

9. LED filament (14) according to any one of the above claims, wherein the carrier element (2) comprises a metal substrate and the first main reflective surface (5) of the carrier element (2) comprises silver.

10. LED filament (14) according to one of the above claims, wherein

the carrier element (2) along its

Main extension direction (3) cooling fins (33), which are formed as fingers and in regular

Extend laterally out of the carrier element (2).

11. LED filament (14) according to any one of the above claims, wherein

the carrier element (2) along its

Main extension direction (3) cooling fins (33) formed as fingers, which are arranged in bundles, wherein the fingers of a bundle radiate away from a common base point (P).

12. LED filament (14) according to any one of the above claims, wherein the carrier element (2) along a longitudinal axis (L) is formed twisted.

13. LED filament (14) according to the preceding claim, wherein the carrier element is rotated such that the first

Main surface and the second major surface of the support member (2) are spirally twisted along the longitudinal axis.

14. A method for producing at least one LED filament (14) according to any one of claims 1 to 3 with the following

steps:

- Providing a support element (2) with a

reflective first major surface (5),

Depositing a plurality of LED chips (4) on the first main surface (5) of the carrier element (2) in a row along a main extension direction (3),

- applying at least one electrical contact point (10, 11) in an end region of the carrier element (2), and

- Serial and / or parallel interconnection of the LED chips (4).

15. The method according to the previous claim, wherein

on a second reflecting main surface (22) of the

Carrier element (2) a further plurality of LED chips (4) in a row along the main extension direction (3)

is applied, wherein the second main surface (22) of the first main surface (5) opposite.

16. A method for producing at least one LED filament (14) comprising the following steps:

Providing a subcarrier (28),

- Applying a plurality of LED chips (4) in a row along a main extension direction (3) on the

Subcarrier (28),

- Embedding the LED chips (4) in a mechanical

stabilizing material (31),

- Remove the subcarrier (28), and

- Applying at least one electrical contact point (10, 11) in an edge region of the LED chip composite.

17. Method according to the preceding claim, with the further steps:

- Applying the LED chip composite to a first

reflecting main surface (5) of a carrier element (2), and

- Applying another LED chip composite on a second reflective main surface (22) of the support member (2), which is the first major surface (5) opposite.

18. The method according to any one of claims 14 to 17, comprising the steps:

Providing a plurality of carrier elements (2) in a carrier (1),

Processing the carrier element (2), and

Separating the carrier (2), so that a plurality of LED filaments (14) is formed.

19. retrofit lamp with an LED filament (14) according to any one of claims 1 to 13.