DE102013219335A1 - Lighting device with substrate body - Google Patents

Abstract

The present invention relates to a lighting device (1) with a substrate body (2) made of plastic material, wherein the substrate body (2) is electrically conductive and thus improved in its thermal conductivity; On the substrate body (2), an optoelectronic component (5) is arranged at a distance therefrom via an electrically insulating coating (4), wherein the coating thickness is not more than 0.5 mm, so that the heat dissipation into the substrate body (2) is not blocked.

Description

Technical area

The present invention relates to a lighting device with a substrate body and an optoelectronic component thereon.

State of the art

Currently developed optoelectronic light sources can be distinguished from conventional incandescent or fluorescent lamps by improved energy efficiency. The terms "optoelectronic component" and "LED" in the context of this disclosure refer to a radiation-emitting optoelectronic component made of a semiconducting material, for. B. on an inorganic or organic light emitting diode.

The present invention is based on the technical problem of specifying a particularly advantageous lighting device with optoelectronic component.

Presentation of the invention

According to the invention, this object is achieved by a lighting apparatus having a primary substrate body with a surface, wherein the substrate body is provided with a coating in a coating surface area, and with an optoelectronic component, which is arranged in the coating surface area, wherein the substrate body comprises a substrate body. Plastic material is provided and is electrically conductive and has a thermal conductivity of at least 5 W / mK, and wherein the coating is provided from a coating plastic material and is electrically insulating and has a coating thickness of at most 0.5 mm, to a heat dissipation of not to block the device in the substrate body.

The substrate body of the lighting device according to the invention is "urgeformt" of a plastic material (see below in detail), so it may for example be an extrusion or injection molded part. The use of plastic material can have the advantage, in comparison to a metallic material, that it can be easier to shape in a simplified way. For example, it may be less energy to spend than for the production of a molten metal or a larger variety of shapes accessible. Incidentally, the plastic material can also offer advantages in terms of cost.

In the operation of the lighting device, however, it may lead to the dissipation of power loss, so that heats up the device. In that regard, a disadvantage of the plastic material may be its comparatively low thermal conductivity. Initial attempts by the inventors were therefore to increase the thermal conductivity of the substrate body by a filler, which should leave the electrically insulating properties of the substrate body unimpaired.

In this respect, z. B. hexagonal boron nitride conceivable as an additive; However, its production can be costly and its use as a filler so be costly, which would mean in particular in mass production not portable additional costs.

The inventors have found that overall, therefore, a different approach offers advantages, even though ultimately it requires the additional insulating coating. It is therefore an electrically conductive filler, for example, electrically conductive filler particles of z. As carbon, embedded in the plastic material of the substrate body. The thus electrically conductive substrate body is (compared to the matrix material) improved in its thermal properties and should have a thermal conductivity of at least 1 W / mK, in this order increasingly preferred at least 3 W / mK, 5 W / mK, 7 W / mK, 9 W / mK, 10 W / mK, 11 W / mK, 12 W / mK, 13 W / mK, 14 W / mK, 15 W / mK.

There are various electrically conductive fillers which, for example, can be produced in a simple and / or wide and therefore inexpensive manner, in particular carbon-based structures.

The coating provided on the substrate body (at least regionally) serves for the electrical insulation of the component, so that, for example, a conductor track structure for electrical contacting of the component can be provided on the coating. The coating thickness is chosen to be comparatively thin, so that the heat dissipation into the substrate body is not blocked (completely interrupted), but in the ideal case only slightly deteriorated. Accordingly, the coating thickness is at most 0.5 mm, more preferably at most 0.45 mm, 0.4 mm, 0.35 mm, 0.3 mm, 0.25 mm, 0.2 mm and 0.15 in this order mm.

The coating thickness is taken along a normal to the substrate body surface (in the thickness direction) and is preferably constant over the coating surface area; otherwise, "coating thickness" refers to an average of the layer thicknesses of the coating over the coating surface area. In the direction perpendicular to the thickness direction Surface directions are determined by the surface area of the coating.

The coating is "electrically insulating", that is, for example, a resistivity of at least 10 ¹⁰ Ω · mm ² / m, in this order increasingly preferably at least 10 ¹¹ Ω · mm ² / m, 10 ¹² Ω · mm ² / m, 10 ¹³ Ω · mm ² / m or 10 ¹⁴ Ω · mm ² / m; independently of this, possible upper limits may for example be at most 10 ²⁵ Ω · mm ² / m, in this order increasingly preferably at most 10 ²⁴ Ω · mm ² / m, 10 ²³ Ω · mm ² / m, 10 ²² Ω · mm ² / m , 10 ²¹ Ω · mm ² / m or 10 ²⁰ Ω · mm ² / m.

On the other hand, in the case of the substrate body, "electrically conductive" may have a resistivity of, for example, at most 10 ⁶ Ω · mm ² / m, 10 ⁵ Ω · mm ² / m, 10 ⁴ Ω · mm ² / m, 10 ³ Ω · mm ² / m, 10 ² Ω · mm ² / m or 10 ¹ Ω · mm ² / m mean (possible lower limits: 5 · 10 ^-2 Ω · mm ² / m or 10 ^-1 Ω · mm ² / m). The "electrical conductivity" of the substrate body refers to this in its entirety, that is, on the bulk material.

Because of the substrate / coating combination according to the invention, it is possible to dispense with a cost-intensive, electrically insulating and at the same time highly thermally conductive filler; Due to the electrically insulating coating, this does not restrict the arrangement / contacting of the device.

In general, a plurality of components may also be provided on the substrate body, for example at least 2, 3, 4, 5, 6, 7, 8, 9 or 10 components. Such a plurality of components is then preferably provided on a continuous with respect to the surface directions, so not interrupted, coating. The component or components are "arranged" in the coating surface area, ie, a projection of the component in the thickness direction onto the substrate body surface should therefore be completely covered by the coating. With regard to the thickness direction, the component is not necessarily arranged directly on the coating, but it is also possible for an additional surface layer serving for mounting the component and / or a printed conductor structure (see below) to be arranged between the component and the coating.

As a "plastic material" (of the substrate body and / or the coating), for example, polypropylene (PP, in particular radiation crosslinked), polyamide (for example PA6, PA66, PA10, PA11, PA12), in particular high temperature resistant polyamide such as PPA or PA46, polyester (for example PBT, PET, PBT / PET, PCT, ABS, ABS / PC), polyphenylene sulfide, LCP and / or PEEK. The plastic material may be provided in particular in the case of the substrate body as a matrix material, in which a filler is embedded (so that the substrate body is electrically conductive).

As far as reference is made in the context of this disclosure to the propagation of radiation or light, this is of course not to imply that for the fulfillment of the object also a corresponding spread must take place; the lighting device should be designed only for a corresponding spread. The terms "radiation" and "light" are used synonymously throughout this disclosure and may generally include, for example, ultraviolet or infrared light; preferably, they relate to the visible region of the spectrum.

Further preferred embodiments can be found in the dependent claims and the description below, while still not being distinguished in detail between the various categories of claims and the disclosure is to be read regarding both the lighting device as well as their manufacture or use concerning.

A preferred embodiment relates to the degree of coverage of the substrate body surface by the coating, ie the area ratio of substrate body surface (total surface area) and coating surface area. Here, the surface area of the coating surface area should be at least 30% in this order increasingly preferably at least 40%, 50%, 60%, 70%, 80% and 90% of the total surface area; more preferably, the substrate body surface is completely covered with the coating, which may possibly facilitate the application of the coating, such as when immersing in a bath (see below).

In a further preferred embodiment, the coating thickness is at least 5 μm, in this order increasingly preferably at least 7.5 μm, 10 μm, 12.5 μm, 15 μm, 17.5 μm, 20 μm, 22.5 μm, 25 μm, 27.5 μm or 30 μm. As far as the coating thickness is limited for thermal reasons up, a minimum thickness for reasons of electrical insulation is preferred.

Also of interest in this respect is the dielectric strength of the coating material, which should preferably be at least 30 kV / mm, in this order increasingly preferably at least 40 kV / mm, 50 kV / mm 60 kV / mm, 70 kV / mm, 80 kV / mm, 90 kV / mm or 95 kV / mm. As a coating material with a corresponding dielectric strength, for example, one of the above-disclosed "plastic materials" may be provided.

In conjunction with a minimum thickness mentioned above, the coating may then for example be at least 0.5 kV, 0.6 kV, 0.7 kV, 0.8 kV, 0.9 kV or 1 kV impact resistant.

In a preferred embodiment, the coating has a thermal conductivity of not more than 2 W / mK, in this order increasingly preferably not more than 1.8 W / mK, 1.6 W / mK, 1.4 W / mK, 1.2 W / mK or 1.1 W / mK. In this case, it is not necessary to set an increased thermal conductivity for the coating, but rather to determine it according to the properties of the coating plastic material itself. In other words, an additional filler for increasing the thermal conductivity can be dispensed with, which offers advantages in terms of cost (And due to the small coating thickness, the heat dissipation does not deteriorate significantly).

The inventively provided substrate body is or is "urgeformt", ie is a solid body, which was formed from a previously usually at least temporarily shapeless material and in the course of molding was substantially brought into its final form / is, for example as an extrusion part or preferably as an injection molded part. For example, the "final shape" is not changed by removing a ridge; "Essentially" means, for example, that the shape remains unchanged at 90%, 95% and 98%, respectively.

In a preferred embodiment, the coating is provided as a circuit carrier, that is, a conductor track structure is arranged on the coating.

The conductor track structure can be applied, for example, in the context of a multi-component injection molding, wherein as a component the coating and as another component about a metallizable plastic is injection molded, which is then coated electronically and / or de-energized in a bath. In an injection molding tool and a carrier with the conductor track structure can be inserted and back-injected with coating and preferably substrate body in a two- or preferably three-component injection molding process.

The conductor track structure can be introduced in such an in-mold technique, for example, by stamping or spraying in the injection mold. In general, preferably not only the coating but also the substrate body is injection-molded, so that the two are molded together.

The conductor track structure can also be embossed, for example, in a hot embossing process onto the coating previously applied to the substrate body (see below) / injection-molded, starting, for example, from a metal foil which is also punched in the embossing press.

It is also possible to apply the conductor track structure by laser direct structuring, wherein a laser beam "writes" the conductor track structure on the surface of the coating, thereby exposing embedded microorganisms in the coating for subsequent metallization.

On the other hand, the conductor track structure can also be applied with methods known from semiconductor manufacturing, ie by appropriate masking, wherein in exposed areas of a large-area applied (paint) mask, for example, the wiring structure can grow or a previously deposited metal layer (under the (paint) mask) are removed can, for example, by etching. Also possible is a plasma deposition, again in conjunction with a mask.

In any case, the conductor track structure is or is preferably applied directly to the coating, that is, for example, directly deposited or grown. So there should be no further material previously applied to the coating, which can simplify the production and reduce costs.

The conductor track structure can, for example, be a thickness of conductor track of at least 1 μm, in this order increasingly preferably 2 μm, 3 μm, 4 μm, 5 μm, 6 μm, 7 μm, 8 μm, 9 μm, 10 μm, 11 μm , or 12 microns have; Possible (independent of the lower limits) upper limits can be, for example, at 100 microns, 80 microns, 60 microns, 40 microns, 30 microns and 20 microns.

In a preferred embodiment, the substrate body has an outer surface area that opposes the device, that is, on the other side of the substrate body; in the case of a plurality of components, these are preferably arranged on one side of the substrate body and the other is a corresponding outer surface area. In any case, a corresponding outer surface area is provided in a preferred embodiment as the outer surface of a luminaire. The lighting device according to the invention must then so back (back related to the Lichtabstrahlrichtungen) are not covered with a housing element of the lamp, but is exposed. It increases the integration depth.

Of course, the outer surface area may also be coated, so part of the coating surface area may at the same time also be outer surface area. in the Generally also independent of the configuration as a luminaire outer surface, preferably in combination therewith, a filler can also be embedded in the plastic material of the coating and / or the substrate body, which serves to adapt the color appearance of the illumination device.

In addition, a filler can also be embedded in the plastic material of the substrate body and / or the coating, for example, in order to impart to the surface diffuse and / or directionally reflecting or specifically absorbing properties; For this purpose, a color pigment is particularly preferably embedded in the plastic material of the substrate body, for example titanium dioxide particles. The reflectivity in the visible region of the spectrum can be, for example, in this order increasingly preferably at least 30%, 40%, 50%, 60%, 70%, 80% and 90%, particularly preferably based on a uniform diffuse reflection.

The invention also relates to a luminaire with a lighting device according to the invention, in particular with a just described lighting device providing an outer surface of the luminaire. For example, "lamp" may mean a device connected directly to the power supply via a socket or a clamping / screwing / soldering contact, in which one or more lighting device (s) may be arranged and held (and electrically contacted via the lamp) ,

The invention also relates, as already mentioned, to the production of a corresponding lighting device, and in particular the possibilities mentioned above for applying the printed conductor structure should also be disclosed in this regard.

The substrate body is in any case urgeformt, so for example injection molded or extruded.

The "injection molding" refers to a substrate body, which is released from a cavity, which was previously supplied at least within certain limits flowable material that is at least partially hardened in the cavity. Preferably, it is supplied under elevated pressure, for example at least 100 bar, 500 bar, or 1000 bar; Possible upper limits may be around 3000 bar, 2500 bar or 2250 bar. The hardening can be carried out, for example, at a hardening temperature which is different from the feed temperature, for example at lower temperatures in the case of a thermoplastic material and at higher temperatures in the case of a thermosetting material.

In general, independently of the specific production of the substrate body, the coating may be applied, for example, by (at least partial) immersing the substrate body in a bath of the coating plastic material; Furthermore, the coating plastic material z. B. also be sprayed. The coating plastic material may also be applied to the substrate body as a powder coating.

In a preferred embodiment, the coating is injection molded, and it should be the above disclosed for the injection molding of the substrate body information also disclosed in this regard. Particularly preferably, the substrate body and the coating are integrally formed in a multi-component injection molding process.

Thus, for example, at least partially flowable plastic material can be supplied to a first cavity and at least partially hardened therein, the part formed in the cavity then delimiting a second cavity, which in turn is at least partially flowable plastic material which at least partially cures therein. For example, the substrate body plastic material can be supplied to the first cavity so that the first cavity releases the substrate body; the surface of the substrate body (or a corresponding part thereof) then delimits the second cavity to which the coating plastic material is fed in order to cure it to the coating formed on the substrate body, in any case in part (removal from the mold is already complete before complete solidification) Networking possible).

Particularly preferred is the production of substrate body and coating in the multi-component injection molding process combined with one of the abovementioned possibilities for applying the conductor track structure.

The invention also relates to the use of a lighting device or a luminaire with such a lighting device for general lighting, in particular for lighting with a fixed lamp, preferably for illuminating a building, such as its immediate environment or preferably its interior.

Brief description of the drawings

In the following, the invention will be explained in more detail with reference to exemplary embodiments, wherein the individual features may also be essential to the invention in another combination and should be disclosed in this form.

In detail shows:

1 a lighting device according to the invention in a sectional view;

2 the heat dissipation of a device in a schematic representation.

1 shows a lighting device according to the invention 1 with an injection molded substrate body 2 , A surface coating area 3 of the substrate body 2 is with a coating 4 made of an electrically insulating coating plastic material (PA6). On the coating 4 are LEDs 5 arranged, and that is finished housed, so before each covered with potting compound LED chips. The LEDs 5 are provided as so-called surface mounted devices, so as SMD components.

At her the coating surface 6 facing undersides have the LEDs 5 flat contact elements, over which they with one on the coating surface 6 arranged (not shown) conductor track structure are electrically connected. The electrically conductive connection between the contact surface and interconnect structure is made via a conductive adhesive.

Per LED 5 provides the trace structure an anode and a cathode contact available, so that the LEDs 5 So can be operated alone on the interconnect structure. On the substrate body 2 or the coating 4 can for the operation of the LEDs 5 Furthermore, a driver / control electronics provided and equally on the interconnect structure with the LEDs 5 be wired.

For the production of the lighting device 1 according to 1 First, the conductor track structure is inserted into a mold, so that during the subsequent injection molding of the coating 4 this is formed on the conductor track structure. In a further injection molding step, the substrate body is then shaped, namely to the surface of the coating facing away from the conductor track structure 4 formed. With a corresponding manufacturing method, a high throughput may be possible, which offers advantages, especially in mass production.

In that regard, the injection molding is advantageous; However, if only plastic were provided as a carrier material, this would have disadvantages in terms of thermal properties. During operation of the lighting device 1 falls on the LEDs 5 namely loss of heat as heat.

Therefore, according to the invention for the substrate body 2 a plastic material with embedded carbon particles 7 intended. The electrically conductive carbon particles 7 increase the thermal conductivity of the substrate body so that it is more than 15 W / mK.

The electrically insulating coating 4 made of PA6 is provided without filler and therefore has only a thermal conductivity of about 1 W / mK. However, since the coating thickness is only 10 μm, the heat dissipation into the substrate body 2 hardly hindered. Assuming an LED area of 1 mm ² , the temperature difference across the coating can be estimated 4 established. In the case of a thermal power of 1 W, they would be in the lighting device according to the invention 1 at about 10 ° C.

Would, however, the substrate body 2 completely out of the for the coating 4 provided plastic material taken without filler, a temperature difference of about 1000 ° C would be set at a substrate body thickness of 1 mm.

With the lighting device according to the invention 1 So is a good thermal connection of the LEDs 5 realized and at the same time ensures their electrical insulation, without the use of a complex thermally conductive and thereby electrically insulating filler.

2 illustrates the comparison just mentioned, that is, in the right half of the picture shows a lighting device according to the invention 1 with electrically (and thus good thermal) conductive substrate body 2 and electrically insulating coating 4 thereon. In the left half of the picture, for comparison, a substrate of the same total thickness is shown, which is made up of the electrically and thermally insulating plastic material of the coating 4 is provided. In the substrate body according to the invention 2 In contrast, the heat is spread well to the side and thus dissipated more efficiently.

Claims (14)

Lighting device ( 1 ) with a urgeformten substrate body ( 2 ) with a surface, wherein the substrate body in a coating surface area ( 3 ) with a coating ( 4 ), and an optoelectronic component ( 5 ) present in the coating surface area ( 3 ), wherein the substrate body ( 2 ) is provided from a substrate body plastic material and is electrically conductive and has a thermal conductivity of at least 5 W / mK, and wherein the coating ( 4 ) is provided from a coating plastic material and is electrically insulating and has a coating thickness of at most 0.5 mm, to heat dissipation from the device ( 5 ) in the substrate body ( 2 ) not to block. Lighting device ( 1 ) according to claim 1, wherein the substrate body surface has a total surface area and the coating surface area ( 3 ) has a coating surface area area, wherein the surface area area of the coating measures at least 30% of the total surface area. Lighting device ( 1 ) according to claim 1 or 2, wherein the coating thickness is at least 5 μm. Lighting device ( 1 ) according to any one of the preceding claims, wherein the coating material has a dielectric strength of at least 30 kV / mm. Lighting device ( 1 ) according to one of the preceding claims, in which the coating has a thermal conductivity of not more than 2 W / mK. Lighting device ( 1 ) according to one of the preceding claims, in which the coating ( 4 ) is provided as a circuit carrier, that is arranged on the coating a conductor track structure. Lighting device ( 1 ) according to one of the preceding claims, in which the substrate body ( 2 ) and the coating ( 4 ) are molded together in a multi-component injection molding process. Lighting device ( 1 ) according to one of the preceding claims, in which the substrate body ( 2 ) has an outer surface area corresponding to the component ( 5 ) is opposite, wherein the outer surface area is provided as the outer surface of a lamp. Luminaire with a lighting device ( 1 ) according to any one of the preceding claims. Method for producing a lighting device ( 1 ) according to one of the preceding claims, in which the substrate body ( 2 ) is uroformed from the substrate body plastic material. The method of claim 10, wherein the coating is applied by at least one of dipping, spraying and powder coating. The method of claim 10 or 11, wherein the coating is injection molded. The method of claim 12, wherein the substrate body ( 2 ) an injection-molded substrate body ( 2 ), wherein the substrate body ( 2 ) and the coating ( 4 ) are molded together in a multi-component injection molding process. Use of a lighting device ( 1 ) according to one of claims 1 to 8 for a lamp, in particular for general lighting, in particular for illumination with a stationary lamp, in particular for illuminating a building, in particular for the interior lighting of a building.

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