WO2017037010A1

WO2017037010A1 - Method for producing light-emitting diode filaments, and light-emitting diode filament

Info

Publication number: WO2017037010A1
Application number: PCT/EP2016/070302
Authority: WO
Inventors: Thomas Schlereth; Ivar TÅNGRING; Tony Albrecht
Original assignee: Osram Opto Semiconductors Gmbh
Priority date: 2015-09-04
Filing date: 2016-08-29
Publication date: 2017-03-09
Also published as: DE102015114849A1; DE102015114849B4

Abstract

In one embodiment, the method produces light-emitting diode filaments (10) and comprises the steps: A) fitting light-emitting diode chips (3) directly onto a first carrier (1), B) covering the light-emitting diode chips (3) with a second carrier (2), C) encapsulating the light-emitting diode chips (3) with a potting body (4) by injection moulding to form a cohesive filament composite (40), wherein the two carriers (1, 2) are used as moulds, and wherein the potting body (4) is integrally formed directly onto the light-emitting diode chips (3), D) removing the first carrier (1) or the second carrier (2) or both carriers (1, 2), E) fitting electrical connections (5) to the potting body (4) and between the light-emitting diode chips (3), so that the light-emitting diode chips (3) are electrically interconnected, and F) separating the filament composite (40) to form the light-emitting diode filaments (10), wherein each of the finished light-emitting diode filaments (10) is mechanically self-supporting, comprises at least eight of the light-emitting diode chips (3) and has a ratio of length to width of at least 15.

Description

description

Method for producing light-emitting diode filaments and light-emitting filament

It is a process for the production of

LED filaments specified. In addition, a light-emitting filament is specified.

The document US 2014/0369036 AI relates to an LED lamp and a filament with such a lamp.

An object to be solved is to provide a method with which LED filaments can be produced efficiently.

This object is achieved inter alia by a method having the features of patent claim 1. preferred

Further developments are the subject of the dependent claims.

In accordance with at least one embodiment, the method produces a light-emitting filament. In which

Light-emitting filament is in particular a luminaire component which is modeled on a filament of a conventional incandescent lamp. The light-emitting diode filament is, for example, a strip which is provided with a plurality of light-emitting diode chips and, in operation, white,

emitted visible light. The light-emitting diode filament is preferably set up in a replica of a

Incandescent lamp to be used and / or to simulate a glow wire.

In accordance with at least one embodiment, the method comprises the step of applying a plurality of LED chips on a first carrier. The

Light-emitting diode chips are preferably applied directly to the first carrier. The first carrier can be a temporary carrier or a permanent carrier for the LED chips. The LED chips can all be identical. Alternatively and preferably at least two or at least three different types of light-emitting diode chips are used. For example, find blue LED chips for excitation of a phosphor use in combination with red light emitting

LED chip. Likewise, first blue-emitting light-emitting diode chips for exciting a phosphor, second blue-emitting light-emitting diode chips for emitting blue light out of the light-emitting filament and additionally red light-emitting light-emitting diode chips can be applied to the carrier, in particular in an alternating sequence.

In accordance with at least one embodiment, the method comprises the step of covering the light-emitting diode chips with a second carrier. Preferably, the second carrier is a temporary carrier which is incorporated into the finished carrier

LED filaments no longer exists.

According to at least one embodiment, the

LED chips placed in a two-dimensional arrangement between the two carriers. The LED chips are preferred for a variety of

LED filaments provided and not just for a single LED filament.

According to at least one embodiment, the

Light-emitting diode chips encapsulated with a potting body. By the encapsulation of the LED chips is preferably formed a coherent filament composite. In the filament composite, all light-emitting diode chips are preferably mechanically integrated. In other words, under the

Manufacturing the LED chips then as a mechanical unit and also as an organizational

Unit to be handled. The filament composite can also be referred to as a synthetic wafer. In accordance with at least one embodiment, the two serve

Carrier, between which the LED chips are mounted, as a mold for the potting body. In other words, then an outer shape of the potting body by a

Determined interface between a potting compound for the potting body and the carriers. It is possible that the carrier, for example, lining inner walls of another, outer mold.

In accordance with at least one embodiment, the potting body is created directly on the light-emitting diode chips. In other words, the potting body encloses the LED chips

directly and is molded onto the LED chips.

In particular, the potting body is connected to the

Light-emitting diode chips attached that in the intended use of the finished light-emitting filaments no detachment of the potting body from the LED chips takes place.

In accordance with at least one embodiment, the method comprises the step of removing the first carrier or the second carrier or both carriers. In the latter

In this case, it is possible that one of the carriers is removed first, and the second at a later stage of the process

Carrier. In accordance with at least one embodiment of the method, electrical connections are made to the potting body and between the light-emitting diode chips. Due to the electrical connections, the LED chips, at least

be electrically connected within one of the later, finished light-emitting filaments. The electrical connections can, for example, connection surfaces for external electrical contacting of the finished LED filaments and interconnects or electrical bridges between

neighboring LED chips as well as between

LED chips and the external electrical

Contain contact surfaces.

In accordance with at least one embodiment, the method comprises the step of uniting the filament composite to the

Light-emitting diode filaments. This process step is preferably a last process step of the production process. Before a singulation can

in particular a functional test of the light-emitting filaments still take place in the filament composite.

In accordance with at least one embodiment, each of the finished light-emitting diode filaments is mechanically self-supporting. In other words, it is not necessary for that to happen

LED filaments later be provided with a mechanical support substrate or applied to a mechanical support substrate. In particular, the LED filaments can thus be attached to two electrical and / or thermal contact points and a

Bridge gap between these contact points without further support or extend away from the contact points. In accordance with at least one embodiment, the light-emitting diode filament comprises at least eight or twelve or twenty of the light-emitting diode chips. Alternatively or additionally lies the

Number of LED chips at most 100 or 50 or 30 or 25.

According to at least one embodiment, the finished

LED filament an elongated shape. This may mean that a ratio of one length to one width of the finished LED filament is at least 10 or 15 or 25. Alternatively or additionally, this is

Ratio of length to width at most 80 or 60 or 40.

In at least one embodiment, the method for producing light-emitting diode filaments is set up and comprises at least the following steps, preferably in the order indicated:

A) applying a plurality of light-emitting diode chips directly to a first carrier,

B) covering the LED chips with a second carrier,

C) encapsulating the LED chips with a potting body to form a coherent filament composite, wherein the two carriers serve as molds or part of casting molds and wherein the potting body is molded directly onto the LED chips,

D) removing the first carrier or the second carrier or both carriers from the light-emitting diode chips and from the potting body,

E) Attaching electrical connections to the

Potting and between the LED chips, so that the LED chips are electrically connected, and F) Separating the filament composite to the

LED filaments, each of which is finished

Light-emitting filaments is mechanically self-supporting,

includes at least eight of the LED chips and a

Ratio of a length to a width of at least 15.

In general lighting, especially in the

Production of retrofits, ie the replication of

Incandescent, increasingly light-emitting filaments used. In this case, a plurality of light-emitting diode chips is arranged on a linear, common substrate and with a

Luminescent material wrapped. When switched on, such an arrangement acts as a classic, glowing filament of an incandescent lamp on a viewer and thus represents directly an important design component of a corresponding product.

However, the production of previously known LED filaments is associated with comparatively great effort. So far, light-emitting filaments are usually produced by sawing glass or sapphire into strips. Subsequently, a metal-glass connection is produced, so that an electrical connection between contact surfaces and the carrier strip is realized. In this case, in particular by mechanical bending or clasping a kind

Lead frame, if necessary with previous adhesive application made. Subsequently, the LED chips are applied to this metal-glass composite and the

LED chips are wired. Subsequently, the phosphor material is applied to each of the filaments. With the method described here, however, it is possible to process the LED filaments together in a filament composite. In particular, a fragile glass carrier or sapphire carrier can be dispensed with, and a

Efficiency of the manufacturing process can be increased, as well as a yield of the process.

According to at least one embodiment is in

Process step D) removes only one of the carriers. In a further method step E2) immediately before step F), the remaining carrier is removed. In the finished

Light emitting diode filaments is thus none of the carriers that are attached in the process steps A) and B),

available .

According to at least one embodiment, the step E) is followed by a step El). In this step, at least one phosphor body is applied to the filament composite. The phosphor body may be unitary and / or continuous and / or extend over at least some of the filaments. That is, the phosphor body can cover the filament composite and in particular the potting body largely or the entire surface, seen in plan view. It can the

Fluorescent body are applied as a film or as a plate or even by printing or spraying on the potting and on the filament composite from step E) are formed.

According to at least one embodiment, the finished LED filaments each exactly a linear arrangement of

LED chips on. In other words, all the LED chips of the LED filament are then located on a common straight line. Alternatively, it is possible that the LED chips are arranged in two straight lines and

For example, are U-shaped electrically connected.

In accordance with at least one embodiment, all

LED chips of the finished LED filament

electrically connected in series. Alternatively, it is also possible for a plurality of series circuits connected in parallel to be present within a finished light-emitting diode filament. In accordance with at least one embodiment, a continuous phosphor body is applied in step E1) on both main sides of the filament composite. In other words, then both main sides of the filament composite with a

Covered phosphor body. It is possible that the phosphor body or bodies completely cover the filament composite, with the exception of electrical contact surfaces for external electrical contacting of the finished

LED filaments. In accordance with at least one embodiment, the finished LED filaments emit the light on two opposite sides. The emitted light is preferably white light. As part of the

Manufacturing tolerances emit the finished

Light-emitting filaments preferably on both sides

same color light.

In at least one embodiment, the first carrier is a permanent carrier still present in the final light emitting diode filaments. With others

Words is then removed in the context of the manufacturing process, then only the second carrier in the course of the manufacturing process. The first, permanent carrier is for example, a heat sink, a phosphor layer or an optical disk, for example with lenses.

In accordance with at least one embodiment, the first, preferably permanent, carrier extends into the finished one

Light-emitting filaments completely over a

Filamentunterseite. Further preferred is one of

Filament underside opposite filament top only partially covered by a phosphor body. In particular, of the phosphor body, only the external ones

electrical contact surfaces released.

In accordance with at least one embodiment, the finished ones are

LED filaments mechanically flexible. This is

achievable in particular by the potting body. The fact that the finished light-emitting filaments are mechanically flexible may mean that they can be bent in the intended use once or several times with a radius of curvature of less than or equal to the length of the finished light-emitting filaments. In this case, the potting body is preferably made of a mechanically flexible plastic and a mechanical connection between the individual

LED chips takes place at least partially over the

Potting body.

As an alternative or in addition to a bending, it is also possible for the finished light-emitting diode filaments to be twisted. For example, then there is a rotation angle along a longitudinal axis along which the finished

Light-emitting filaments can be twisted once or several times temporarily or permanently nondestructively, at least 45 ° or 90 ° or 120 °. By such

twistable light-emitting filaments it is possible in one Replica of a light bulb a particularly uniform

Radiation towards all sides. The twisting of the light-emitting filaments is in particular made possible by the use of the potting body, as compared to a rigid support, such as glass or sapphire.

According to at least one embodiment are in the

Light emitting diode filaments integrated one or more heat sinks. Heat sink means, for example, that a thermal conductivity of a material of the heat sink is at least 50 W / m-K or at least 100 W / m-K or 120 W / m-K. In particular, the heat sink is made of a

thermally conductive metal such as aluminum and / or copper formed or consists predominantly thereof.

In accordance with at least one embodiment, the heat sink is electrically isolated from the electrical connections. This makes it possible, a thermal bonding of the finished LED filaments independent of an electrical

Make contact. In particular, that can

LED filament then have a large area designed thermal contact surfaces, for example, with an area of at least 5 mm ² .

According to at least one embodiment, the

Heat sink and / or thermal contact surfaces on the one hand and the electrical contact surfaces for external electrical contacting on the other hand in the finished

LED filaments on opposite sides

Main pages. In particular, the electrical

Contact surfaces on the top of the filament and the heat sink and / or the thermal contact surfaces on the

Filament base. In accordance with at least one embodiment, the heat sink is formed by a coherent layer, which lies in a plane below the potting body and the

LED chips is located. In other words, that is

Heat sink then approximately in the form of the first carrier to the

LED chips mounted and the LED chips are then on the heat sink. In accordance with at least one embodiment, the heat sink comprises or consists of a shadow mask. In this case, one or more of the light-emitting diode chips is preferably placed in each hole of the shadow mask in step A). In other words, the light-emitting diode chips and the heat sink or at least the shadow mask lie in a common plane.

In accordance with at least one embodiment, in step C), a strong mechanical connection is established between the light-emitting diode chips and the shadow mask by creating the potting body. That is, in each hole of the shadow mask with a light-emitting diode chip then a material of the potting body can be filled, so that the LED chips over the

Potting body to be fitted and fixed in the holes. According to at least one embodiment, the

Potting the heat sink and in particular the shadow mask, seen in plan view, completely. That is, a thickness of the potting body then preferably exceeds a thickness of

Shadow mask. In particular, the potting extends beyond the

Hole mask only on one side and closes on another side, preferably on the filament underside, flush with the shadow mask. In accordance with at least one embodiment, the heat sink comprises a bottom plate in addition to the shadow mask. The shadow mask is preferably mounted directly on the bottom plate. It is possible that the bottom plate and the shadow mask are formed integrally. The bottom plate is preferably free of recesses or openings through the bottom plate

through, so that the bottom plate can form a coherent, massive and uninterrupted layer. Here, the potting completely cover the bottom plate, seen in plan view.

In accordance with at least one embodiment, the carriers or covers at least one of the carriers in step C) only partially cover the main sides of the light-emitting diode chips. In other words, the main sides of the LED chips are then partially free. This makes it possible that the potting body is also formed in places on the main sides of the LED chips. That way you can

Anchoring structures are formed, by means of which the light-emitting diode chips are mechanically better integrated into the potting and / or the filament composite.

According to at least one embodiment, the

LED chips in step H) applied alternately on the first carrier. This may mean that at the

LED chips alternately an n-side and a p-side is above. The LED chips are thus applied alternately rotated by 180 ° from each other. Alternatively, it is possible that there is also a rotation of only 90 ° between adjacent light-emitting diode chips, for example in order to achieve an all-round emission of the finished light-emitting diode filaments. In accordance with at least one embodiment, the finished light-emitting filaments have a length of at least 15 mm or 20 mm or 30 mm. Alternatively or additionally, the length of the finished light-emitting filaments is at most 100 mm or 60 mm or 45 mm.

In accordance with at least one embodiment, a width or average width of the LED filaments is at least 0.5 mm or 0.8 mm or 1.1 mm. Alternatively or additionally, the width is at most 5 mm or 3 mm or 2 mm or 1.8 mm. The width is preferably determined in the direction parallel to the main sides of the carrier. The width of the finished light-emitting filaments is thus determined in particular by the separation in step F).

According to at least one embodiment, the

Light-emitting filaments have a thickness of at least 0.6 mm or 0.8 mm or 1.2 mm. Alternatively or additionally, the thickness is at most 3 mm or 2 mm or 1.6 mm. The thickness is preferably not or not in step F)

significantly influenced.

In accordance with at least one embodiment, the heat sink has a thickness of at least 0.15 mm or 0.2 mm or 0.3 mm. Alternatively or additionally, the thickness of the

Heat sink not more than 1 mm or 0.8 mm or 0.5 mm. Here, a main component of the heat sink is preferably a metal such as copper or aluminum. Main component means that a weight proportion of the corresponding substance at the

Total heat sink is at least 60% or 80% or 95%. In accordance with at least one embodiment, the finished ones are

Light-emitting filaments free from a glass carrier or a sapphire carrier. This does not exclude that the individual light-emitting diode chips have about a sapphire carrier, however, such a sapphire carrier does not extend over the entire LED filament and is about for a

mechanical stabilization of the LED filament

overall not or not significantly significant.

In accordance with at least one embodiment, the finished ones are

LED filaments adapted to be plugged or clamped in an external fixture. In this way, the LED filaments are electric

and / or thermally externally contacted.

According to at least one embodiment, the

Casting particles or admixtures to improve thermal conductivity. For example, the potting body then contains particles of a metal oxide such as titanium dioxide or zirconium dioxide or tantalum oxide. Likewise, the potting body metal particles or coated

Have metal particles. The particles may be spherical or polyhedral shaped or in the form of

elongated threads present.

In accordance with at least one embodiment, the potting body is reflective to visible light. In particular, the potting body appears white to a viewer.

According to at least one embodiment, the

Potting body at least one phosphor. It is possible that the potting body contains the same phosphor as the phosphor body and / or the phosphor layer. Thereby For example, it is possible for radiation emerging laterally from the light-emitting diode chips not to be reflected at the potting body, but instead to be converted in the phosphor body and / or in the phosphor layer. For the light generated by the phosphor, the potting body is preferably made clear or scattering.

In accordance with at least one embodiment, the potting body is permeable to visible light, in particular clear-vision and transparent. Alternatively, the potting may appear milky cloudy.

In addition, a light-emitting filament is specified. The LED filament is preferably made by a method as recited in connection with one or more of the above-identified embodiments. Features of the method are therefore also disclosed for the LED filament and vice versa. In at least one embodiment, this is

LED filament adapted to, in one

Bulb replacement to be used as a replica of a filament. A proper operating voltage of

LED filaments is preferably at least 30 V or 45 V or 60 V and / or at most 400 V or 240 V or 115 V or 90 V or 80 V.

Hereinafter, a method described herein and an LED filament described herein with reference to the drawings by means of embodiments closer

explained. The same reference numerals indicate the same elements in the individual figures. However, there are no scale relationships shown, but rather individual Elements for oversimplification may be exaggerated.

Show it:

Figures 1 to 8 are schematic representations of here

described method for the production of light-emitting diode filaments described here. FIG. 1A shows, in a schematic sectional view, a method step of a method for producing light-emitting diode filaments 10 described here. On a first carrier 1, a plurality of light-emitting diode chips 3

appropriate. The carrier 1 is, for example, a mechanically flexible film or else a rigid one

Substrate. The light-emitting diode chips 3 each have a chip substrate 33 on which a semiconductor layer sequence 30 is mounted. According to FIG. 1A, all n-sides 31 point towards the first carrier 1 and all p-sides 32 away from the first one

Carrier 1.

Notwithstanding Figure 1A can also from each other

various LED chips 3 are used. The light-emitting diode chips 3 shown in FIG. 1A preferably each have a light-permeable chip substrate 33 made of sapphire and can therefore emit radiation on all sides. The semiconductor layer sequence 30 is preferably based on AlInGaN, so that the light-emitting diode chips 3 are set up, for example, to produce blue light.

In the method step, as shown in FIG. 1B, a second carrier 2 is applied to the light-emitting diode chips 3. By the second carrier 2, which is for example a If the film is a sealing of a volume, so that a potting body 4 can be generated in the subsequent process step. In FIG. 1C1, in a sectional representation and in FIG. 1C2, in a schematic plan view, the creation of the

Potting 4 illustrated. The potting body 4 is made for example of a silicone, epoxy or silicone-epoxy hybrid material. The potting 4 may be an admixture, for example, for setting a

Thermal conductivity or for adjustment of optical

Have properties. In the example of FIG. 1, the potting body 4 appears white to a viewer and is

reflective for visible light. Alternatively, the

Potting body 4 provided with a phosphor and otherwise be transparent. Through a fluorescent in the

Potting 4 is a lateral emission of

LED chips 3, so an emission, in particular along the longitudinal axis of the LED filament 10, directly convertible into light of another wavelength.

It can be seen in FIG. 1C2 that the light-emitting diode chips 3 are arranged two-dimensionally. All light-emitting diode chips 3 are mechanically connected via the potting body 4. The LED chips 3 are for a variety of

LED filaments 10 set up. Thus, a filament composite 40 is produced by the potting 4. The filament composite 40 is a synthetic wafer, with which the later light-emitting filaments 10 to be separated can be handled together.

According to the sectional illustration in FIG. 1D1 and the plan view in FIG. 1D2, the two carriers 1, 2 are removed. To the Ends of the later, finished light-emitting filaments 10, an external electrical contact surface 55 is generated in each case in strip form. The contact surface 55 is produced, for example, by adhering a printed circuit board film, by screen printing, by paste printing, by jetting or by electroplating.

Unlike what is shown, it is not necessary for the contact surface 55 to be a continuous strip across a plurality of the later light-emitting filaments 10

extends. In the process step, as shown in Figures 1E1 and 1E2, the LED chips 3 are towards the contact surfaces 55 and each other via electrical

Connections 5 electrically connected. The electrical connections 5 are bonding wires. Instead of bonding wires can also planar connections such as

Printed conductors, such as by photo technology or screen printing or jetting, are applied. Also a vaporization of

corresponding electrical connections 5 is possible.

As in the sectional view in Figure 1F1 and in the

Top view shown in Figure 1F2, both on a filament base 11 and on a filament top 12, at which the electrical connections 5 and the

Contact surfaces 55 are located, each phosphor body 8 applied. The phosphor bodies 8 preferably leave free an edge region on the contact surfaces 55, both on the filament underside 11 and on the filament upper side 12.

The phosphor body 8 on the lower side of the filament 11 is, for example, a silicone film or else a glass plate which contains a phosphor or a phosphor Phosphor mixture is added. This can also apply to the phosphor body 8 on the upper side of the filament 12.

Alternatively, the phosphor body 8 at the

Filament top 12 by imprinting or

Injection molding or injection molding produced analogous to

Potting body 4.

Furthermore, it is possible that the two phosphor bodies 8 are replaced by a single, not shown phosphor coating. Such a phosphor coating, the alternative or in all other embodiments

in addition to the phosphor body 8 or to the

Phosphor layer 7 may be present, for example, by immersing the filament in a bath

Converter material or produced by dispensing. With such a phosphor coating can be cylindrical or nearly cylindrical LED filaments 10, in particular with a uniform radiation in all directions transverse to a longitudinal axis of the LED filament 10 realize.

As in all other embodiments, it is possible to provide one or more transparent protective layers in place of the phosphor body or bodies 8, which then have no wavelength-changing properties.

The separation towards the finished light-emitting diode filaments 10 is illustrated in the sectional representation in FIG. 1G1 and in the plan view in FIG. 1G2. The resulting LED filaments 10 are mechanically self-supporting and can be mechanically flexible or rigid. The

Separation to the LED filaments 10 takes place

for example, by sawing, by a scoring together with breaking, by punching or by a laser cutting process. With this method, the light-emitting diode chips 3 can be integrated into the filament composite 40, the filament composite 40 being a synthetic wafer in which the processing can be carried out efficiently at the panel level. Such a potting body 4 for the filament composite 40 is cost-effectively manufacturable and adjustable in terms of mechanical properties by suitable choice of the material for the potting 4.

In particular, due to the potting 4 are

comparatively time-consuming, expensive and susceptible to breakage

Sawing process steps such as glass and eliminating the need to make metal-glass contacts with conventional light-emitting diode filaments. Furthermore, a high mechanical stability and a high dimensional accuracy can be achieved during processing, in comparison to previously customary, fragile metal-glass-conductor frame assemblies. Also, the application of the phosphor body 8 is still possible in the filament composite 40.

In Figure 2 is in sectional views another

Illustrated embodiment of the manufacturing method. Notwithstanding Figure 1, the LED chips 3

alternately with an n-side 31 and a p-side 32 mounted on the first carrier 1. As a result, bidirectional or omnidirectional radiation similar to a glow wire in an incandescent lamp can be realized in the later, finished light-emitting diode filaments 10. According to FIG. 2B, the second carrier 2 is attached and, according to FIG. 2C, the potting body 4 and the filament composite 40 are produced. FIGS. 2D and 2E show the electrical connection of the LED chips 3. In this case, two series circuits are realized, see Figure 2E. In a series circuit are all the LED chips 3 with the p-side 32nd up and in a second series circuit all LED chips 3 with the p-side 32 down. In each case not addressed in a series circuit, intervening LED chips 3 are connected to the electrical connections 5a, which can be configured as interconnects

bridged. This is possible because the chip substrates 33 are formed from an electrically insulating material or are coated in an electrically insulating manner. In this case, the electrical connections 5a cover the associated

LED chips 3 preferably completely, seen in plan view.

Unlike in FIG. 2E, it is possible that at one end of the light-emitting diode filament 10 a

Through-hole through the potting 4 through

is provided. As a result, the series connection on the upper side of the filament 12 with the series circuit at the

Filament bottom 11 are electrically connected in series, so that then the contact surfaces 55 may be located at a single end of the LED filament 10, wherein one of the only in this case two external electrical contact surfaces then on the lower side of the filament 11 and another

Contact surfaces 55 is attached to the filament top 12. Analogously to FIG. 1, the light-emitting diode chips 3 are each provided with a single, coherent phosphor body 8 on the lower side of the filament 11 as well as on the upper side of the filament 12. As in all other embodiments, the at least one phosphor body 8 preferably has a homogeneous material composition and a uniform thickness.

Deviating, it is possible that the phosphor body 8 in alternating thicknesses is applied, so that

For example, thinner areas of the phosphor body 8 are located between adjacent light-emitting diode chips 3.

Alternatively, at least one of the phosphor bodies 8 or both phosphor bodies 8 can be designed in a lenticular fashion in some areas, wherein then preferably each of the

LED chips 3 is associated with a lens section.

FIG. 3 shows a further exemplary embodiment. The method steps of FIGS. 3A to 3D are analogous to FIG. 1. In the method step of FIG. 3F, a heat sink 6 is applied over the entire surface of the filament underside 11. The heat sink 6 is for example off

Formed aluminum and preferably has a thickness of at least 150 ym. Likewise, the heat sink 6 can act as a mirror for radiation generated in the LED chips 3. In this case, the finished emits

LED filament 10 radiation only at the

Filament top 12 and not on the filament underside 11. The further process steps of Figures 3F and 3G are analogous to Figure 1.

By such a heat sink 6 is an improved

Heat dissipation and cooling of the LED chips 3 can be realized. Furthermore, such a heat sink 6 can be thermally connected at least pointwise to an external cooling plate.

According to FIG. 3, the heat sink 6 is located below the potting body 4. In the exemplary embodiment, as illustrated in FIG. 4, the heat sink 6 is in the form of a shadow mask 61

educated. According to FIG. 4A, one of the light-emitting diode chips 3 is placed in each region of the light-emitting diode filaments 10 in each hole of the shadow mask 61. In the next step, see Figure 4B, the holes are filled with the potting body 4, so that the filament composite 40 is formed. The heat sink 6 closes at the

Filament base 11, not drawn, flush with the

Shadow mask 61 from. At the top of the filament 12, the potting body 4 closes, as well as in the other

Embodiments, flush with a main side of the

This applies preferably not at an edge of the later, finished LED filaments 10, so that at this edge the finished LED filaments 10 are thermally contacted via the shadow mask 6. In the next method step, see FIG. 4C, the electrical contact surfaces 55 are attached. In this case, the contact surfaces 55 are preferably each between two adjacent regions of the heat sink 6 at the edge. The contact surfaces 55 can continue toward the

LED chips 3 protrude as the exposed areas of the heat sink 6.

FIG. 4D shows that the light-emitting diode chips 3 are electrically connected to the connection means 5. According to FIG. 4E, the phosphor body 8 is produced. According to FIG. 4F1, singulation takes place. The resulting

Light-emitting filament 10 is shown in Figure 1F2 in a plan view. In the heat sink of Figure 4 is both a good

Heat dissipation as well as a two-sided or omnidirectional radiation achievable. Furthermore, the electrical contacts and the thermal external contacts are separated from each other. Various embodiments of the shadow mask 61 are shown schematically in FIG. 5, as in connection with FIG. 4

usable. According to the sectional view in FIG. 5A, the shadow mask 61 has a smaller thickness than the one

LED chips 3 and, in the context of

Manufacturing tolerances, the shadow mask 61 is provided with vertical side walls. The potting body 4 is preferably reflective and white in this case.

In the embodiment of the sectional view in Figure 5B, the side walls of the shadow mask 61 are inclined to

Side surfaces of the LED chips 3 arranged. In the case of a radiation-transmissive, transparent Vergusskörpers 4, the side walls of the shadow mask 61 can serve as reflectors to allow a more directional radiation of the light.

In the sectional view according to FIG. 5C, it is shown that the heat sink 6 contains the shadow mask 61 and, in addition, a

Bottom plate 62 has. The LED chips 3 sit on the bottom plate 62. This is a special

Efficient heat dissipation feasible. The mechanical

Properties of the LED filament 10 are then in

Essentially determined by the heat sink 6. For example, in the case of a mechanically flexible, self-supporting film for the heat sink 6 and the associated LED filament 10 is mechanically flexible realized. The top view in FIG. 5D shows that in FIG

Areas between adjacent LED filaments 10 singling slots 69 may be present. Along this separation slots 69 is then preferably a Dicing and singulation to the LED filaments 10. The dicing slots 69 may have various shapes as seen in plan view as in FIG. 5D

illustrated.

In FIGS. 4 and 5, the holes in the shadow mask 61, viewed in plan view, are each shaped in a square or rectangular manner. Deviating from this can also round holes

used, seen in plan view. This is

in particular in reflector-like configurations analogous to Figure 5B advantageous.

In the embodiment of the method, as in the

Sectional views of Figure 6, the heat sink 6 is used as the first carrier 1. Thus, the first carrier 1 remains permanently in the LED filament 10. The remaining process steps are performed, for example, analogously to FIG. In the exemplary embodiment of FIG. 7, the first carrier 1 used is the phosphor body 8, which is also permanently attached to the

LED chips 3 remains. The phosphor body 8 in this case is, for example, a glass plate or plastic plate offset with the phosphor. Also in the process according to FIG. 7 the remaining ones are used

Process steps preferably carried out analogously to Figure 1.

In this method, as illustrated in Figures 6 and 7, a temporary intermediate carrier can be dispensed with and only a total of a temporary support 2 for sealing in the

Generation of the potting 4 required. In particular, a better optical and / or thermal coupling of the first carrier 1 to the LED chips 3 can be realized. In the method, as shown in the sectional views of Figure 8, a mold 9 is used. By this mold 9, the two carriers 1, 2 are not applied over the entire surface of the LED chips 3. This will, see

FIG. 8C, the main sides of the LED chips 3 partially covered by the potting body 4. As a result, anchoring structures 43 are formed on edges of the LED chips 3. About these anchoring structures 43 is an improved mechanical anchoring of the LED chips 3 in comparison to the embodiments of Figures 1 to 7

realizable. Corresponding anchoring structures 43 may also be present in all other exemplary embodiments.

The invention described here is not by the

Description limited to the embodiments.

Rather, the invention encompasses any novel feature as well as any combination of features, including in particular any combination of features in the claims, even if this feature or combination itself is not explicitly stated in the patent claims or exemplary embodiments. This patent application claims the priority of German Patent Application 10 2015 114 849.8, the disclosure of which is hereby incorporated by reference. Reference sign list

1 first carrier

2 second carrier

3 LED chip

30 semiconductor layer sequence

31 n page

32 p-side

33 chip substrate

4 potting bodies

40 filament composite

43 anchoring structure

5 electrical connection

55 electrical contact surface 6 heat sink

61 shadow mask

62 base plate

69 singling slot

7 phosphor layer

8 phosphor bodies

9 casting mold

10 light-emitting diode filament

11 filament base

12 filament top

Claims

claims

Method for producing light-emitting diode filaments (10) with the steps:

A) applying a plurality of light-emitting diode chips (3) directly to a first carrier (1),

B) covering the LED chips (3) with a second carrier (2),

C) encapsulating the LED chips (3) with a

Potting body (4) to a coherent

Filament composite (40), wherein the two carriers (1, 2) serve as molds and wherein the potting body (4) is molded directly to the LED chips (3),

D) removing the first carrier (1) or the second carrier (2) or both carriers (1, 2),

E) attaching electrical connections (5) to the potting body (4) and between the light-emitting diode chips (3), so that the light-emitting diode chips (3) electrically

be interconnected, and

F) singulating the filament composite (40) to the

Light-emitting diode filaments (10),

wherein each of the finished LED filaments (10) is mechanically self-supporting, at least 8 of

Comprising light emitting diode chips (3) and having a length to width ratio of at least 15.

Method according to the preceding claim,

wherein the method steps A) to F) in the

specified order,

wherein in method step D) only one of the carriers (1, 2) is removed and in a method step E2) immediately before step F) the remaining carrier (1, 2) is removed, wherein the step E) is followed by a step El), in which at least one phosphor body (8) on the

Filament composite (40) is applied, and

wherein the finished LED filaments (10) each exactly a linear arrangement of the LED chips (3)

and each of all light-emitting diode chips (3) of the finished light-emitting filaments (10) electrically in series

are switched.

Method according to the preceding claim,

in step El) on both main sides of the

Filament composite (40) at least one phosphor body (8) is applied so that the finished

Light-emitting filaments (10) at two each other

emit light on opposite sides and this light is white light.

Method according to claim 1,

in which the first carrier (1) is a permanent carrier which is still present in the finished light-emitting diode filaments (10), so that only the second carrier (2) in the

Removed course of the manufacturing process, wherein the first carrier (1) is a heat sink (6) or a phosphor layer (7), and

wherein the first carrier (1) in the finished

Light-emitting diode filaments (10) completely over a

Filament underside (11) and one of the

Filament bottom (11) opposite

Filament top (12) partly from one

Phosphor body (8) is covered.

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

in which the finished light-emitting filaments (10)

non-destructive with a radius of curvature smaller or the length of the finished light-emitting filaments (10) can be bent,

wherein the potting body (4) consists of a mechanical

flexible plastic is produced.

Method according to one of the preceding claims, in which in each of the light-emitting diode filaments (10)

Heat sink (6) is integrated,

wherein the heat sink (6) from the electrical

Compounds (5) is electrically isolated, and

wherein the heat sink (6) and electrical

Contact surfaces (55) for external electrical

Contacting the finished light-emitting filaments (10) are located on opposite main sides.

Heat sink (6) is integrated,

wherein the heat sink (6) comprises or consists of a shadow mask (61),

wherein in each hole of the shadow mask (61) in step A) at least one of the light-emitting diode chips (3) is placed, and

wherein in step C) by the potting body (4) has a fixed mechanical connection between the

LED chip (2) and the shadow mask (61) is produced and the potting body (4), the shadow mask (61), seen in plan view, completely covered.

Method according to the preceding claim,

in which the heat sink (6) comprises a bottom plate (62) in addition to the shadow mask (61),

wherein the shadow mask (61) is mounted on the bottom plate (62) and the potting body (4) and the Bottom plate (62), seen in plan view, completely covered.

Method according to one of the preceding claims, in which the carriers (1, 2) in step C) only partially cover main sides of the light-emitting diode chips (3) so that the potting body (4) is also formed in places on the main sides of the light-emitting diode chips (3) and thus Anchoring structures (43) are formed.

Method according to one of the preceding claims, in which in step A) the light-emitting diode chips (3)

alternately with an n-side (31) and a p-side (32) are applied overhead on the first carrier (1).

Method according to one of the preceding claims, in which the finished light-emitting filaments (10) have a length of between 20 mm and 60 mm inclusive, a width between 0.8 mm and 3 mm inclusive and a thickness between 0.8 mm and 2 mm inclusive, wherein a thickness of the heat sink (6) between

including 0.2 mm and 0.8 mm and a

Main component of the heat sink (6) copper or

Aluminum is.

Method according to one of the preceding claims, wherein the finished LED filaments (10) are free of a glass carrier or a sapphire carrier, wherein the finished LED filaments (10) are adapted to be inserted or clamped in an external holding device to a

electrical and thermal external contact

to produce.

13. The method according to any one of the preceding claims, wherein the potting body (4) comprises particles for improving the thermal conductivity of the potting body (4),

wherein the potting body (4) is reflective or translucent to visible light.

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

in which the potting body (4) at least one

Includes phosphor.

15. A light-emitting diode filament (10) produced by a method according to any one of the preceding claims, wherein the light-emitting filament (10) is adapted to be used in a replacement bulb as a replica of a filament,

wherein a proper operating voltage of the LED filament (10) is between 30 V and 400 V inclusive.