DE102013203664A1 - Substrate for lighting device e.g. LED light module, has ceramic portion made of electrically insulating ceramic material and cermet portion which is formed as electrical strip conductor to which metal structure is attached - Google Patents

Abstract

The substrate (11) has a ceramic portion made of electrically insulating ceramic material and cermet portion. The cermet portion is configured to form a portion of surface of the substrate. The cermet portion is formed as electrical strip conductor. A metal structure formed as cooling structure, is attached to the cermet portion. An independent claim is included for method for manufacturing substrate.

Description

The invention relates to a substrate for a lighting device, wherein the substrate has at least one ceramic region of electrically insulating ceramic. The invention also relates to a method for producing such a substrate. The invention is particularly applicable to substrates for LEDs, in particular with cooling bodies arranged thereon.

There are known substrates for light-emitting diodes (LEDs), which consist of ceramic. Ceramic has the advantage that it is highly thermally conductive and is highly electrically insulating in most cases. However, there is a problem in attaching metallic bodies to the ceramic substrate, e.g. Tracks or heatsinks. To apply printed conductors on a ceramic substrate, this must be activated, usually with palladium, which is complicated and expensive. A heat sink is typically attached to the ceramic substrate by means of a primer (e.g., a thin double-sided adhesive tape, thermal grease, etc.). In this case, it is disadvantageous that the heat transfer resistance between the ceramic substrate and the heat sink is comparatively high due to the adhesive tape.

It is the object of the present invention to at least partially overcome the disadvantages of the prior art and in particular to provide a simplified possibility for attaching metallic bodies to a ceramic volume.

This object is achieved according to the features of the independent claims. Preferred embodiments are in particular the dependent claims.

The object is achieved by a substrate for a lighting device, wherein the substrate has at least one subregion made of electrically insulating ceramic (hereinafter referred to as "ceramic subregion") and at least one subregion made of cermet (hereinafter referred to as "cermet subregion") , Cermets are composites of ceramic materials in a metallic matrix. Cermets are typically sintered materials and thus can advantageously be manufactured in one piece by sintering with the ceramic subregion. Cermets have the further advantage that they can be connected like metal with other metal bodies, so that can be used in common bonding or manufacturing processes between metals. Elaborate bonding techniques between ceramic and metal such as activating or using the primer can be dispensed with. Metal-to-metal bonding methods such as soldering or welding allow a significantly lower heat transfer resistance between the substrate and an associated metal body.

The ceramic or the ceramic component of the cermet often consists of alumina and / or zirconia, while the metallic components often niobium, molybdenum, titanium, cobalt, zirconium or chromium are used. It is preferred that the ceramic of the cermet corresponds to the ceramic of the ceramic portion, since such a material mismatch is reducible.

Cermets may be electrically conductive or electrically nonconductive. This may be e.g. be dependent on a ratio of the proportions of ceramic to metal. A volume ratio of ceramic to metal of 40:60 is preferred.

It is an embodiment that the at least one cermet subregion forms part of a surface of the substrate. Thus, a metal body can be attached directly to this part.

It is still another embodiment that the substrate has a ceramic portion having a first side (hereinafter referred to as "front side" without limitation) and a second side (hereinafter referred to as "backside") At least one cermet subarea is connected to the front side and / or the rear side. This has the advantage that a metallic body can be easily attached to the front and / or back of the cermet portion.

It is a development that the substrate has a plate-shaped basic shape. The substrate may be full-surface in the plane of the largest extents (e.g., in an x-y plane) or may have recesses extending through the entire thickness (in z-extension).

The plate-shaped substrate need not be flat, but may be e.g. also be curved in one or in two directions. In general, the substrate is not limited to a plate-like basic shape, but may have any suitable shape.

It is a further embodiment that at least the front side has at least one, at least partially superficially extending, electrically conductive cermet portion as an electrical conductor track. The at least one cermet subarea can therefore serve as a conductor even if the cermet is sufficiently electrically conductive. Thus, no subsequent metallization is necessary.

It is a development which can be used for electrically conductive or electrically non-conductive cermet subareas that at least one cermet subregion has a form of an electrical conductor track and a metallic conductor track is applied thereon. Such interconnects are particularly easy to apply to the substrate, for example by conventional metallization, without a previous activation is necessary.

It is an embodiment of the fact that the existing of the electrically conductive cermet portion conductor track ("cermet track") is completely superficial. Such a configuration is particularly easy to produce. For example, such a cermet portion may be produced by powder pressing a green body by filling cermet powder into a correspondingly shaped female mold negative mold. In particular, this provides a raised cermet trace that is easily contactable, e.g. from an LED chip or a bonding wire.

It is also an embodiment that the cermet conductor runs partially in the ceramic subregion, ie in particular is laterally completely surrounded by the ceramic subregion. As a result, the cermet track can also run in the depth (below the surface of the substrate) of the ceramic subregion. This, for example, allows electrical conduction below an electrically insulating surface, resulting in e.g. multi-layered line levels and / or touch-safe surfaces can be provided.

It is also an embodiment that connects at least one cermet portion at least one metallic body. Such a metallic body is particularly easy to connect, in particular by metal-metal compound types, metal-plastic compound types or a coating. This embodiment has the advantage that a primer, e.g. an adhesive tape can be dispensed with and thus sets a particularly low heat transfer resistance.

It is a development that the metallic body is a conductor track or a contact pad ("bonding pad"). In this case, the trace or contact area may be e.g. have been applied to the cermet portion without prior activation, e.g. by conventional coating methods or metallization.

It is also an embodiment that at least one metallic body is a separately produced body and then attached to at least one cermet portion. This can be done especially by a metal joining method, e.g. by soldering or welding.

It is still an embodiment that at least one metallic body is an integral with the cermet portion metallic body. An integral adjoining body is understood in particular to mean a body which is produced simultaneously with the production of the cermet subregion or of the cermet subregion and of the ceramic subregion and is not subsequently attached to an already finished cermet subregion. For example, the green body may also have metallic subregions, e.g. made of sinterable metal. Thus, during a common sintering process, at least one ceramic subregion, at least one cermet subregion and at least one metallic subregion of the substrate can be produced in a very general manner. This embodiment allows a reduction in the number of steps and thus may allow a particularly simple and inexpensive substrate.

It is a further embodiment that at least one metallic body is a heat sink. This may therefore be connected to the substrate with a particularly low heat transfer resistance, which enables particularly effective heat removal, e.g. of semiconductor light sources and / or electronic components attached to the substrate.

It is also an embodiment that at least one metallic body is at least partially buried in the ceramic subregion and is encompassed by at least one associated, in particular electrically conductive, cermet subregion. As a result, an effective mechanical fixation and / or electrical contacting of the metallic body can be achieved in a simple and reliable manner. Additionally or alternatively, the at least one metallic body may be at least partially buried in or surrounded by a cermet subregion.

The metallic body may for example be realized from a metallic powder trace introduced into the green body or by inserting a metallic insert into ceramic and / or cermet powder before a pressing process and / or a sintering process.

It is also an embodiment that at least one cermet subregion is a gradient region, that is to say that at least in one direction of extent (for example over its thickness) it has gradually changing ceramic-metal fractions. This enables an improved connection on the one hand to a ceramic subregion, e.g. with a particularly low mechanical mismatch, and on the other hand to a metal, e.g. with a very low heat transfer resistance.

It is a further development that the gradient region has two or more subregions or graduations which have a constant ceramic-metal component but different ceramic-metal components. This may be realized in particular in the form of a layer-like gradient region. This development is characterized by its particularly simple implementation, for example, by powder or other starting material with different ceramic-metal content layer by layer are entered into a green body shape.

It is also an embodiment that the substrate has been produced by means of a method comprising at least the following steps: producing a green body, the green body having regions of ceramic starting material and regions of cermet starting material; and sintering the green body to the substrate.

The sintering may for example be pressureless sintering, wherein the production of the green body and the sintering can be realized in particular as different working steps. However, sintering may also be a gas high pressure sintering, in particular a hot isostatic pressing (HIP). In this case, the production of the green body and sintering may take place in a common work step. In yet another variant, for example, a sintering process can be carried out under normal pressure until the open porosity in the sintered body is closed, followed by a HIP cycle. This process, referred to as sintering HIP or post-HIP, can be carried out in another apparatus than sintering under normal pressure or subsequently in the same apparatus. In general, the substrate may be made by any (any suitable) sintering process, e.g. also by means of spark plasma sintering, SPS.

The green body may have been made in any of a number of known ways, e.g. by powder pressing or wet-chemical.

For the integral production of at least one metallic subregion or body of the substrate, the green body may also have at least one metal region. The metal region may in particular consist of sinterable metal, but is not limited thereto.

It is still a development that the substrate is a substrate for a lighting device and is configured as a substrate or support for at least one light source. For this purpose, the substrate may, for example, have placement sites for at least one light source. This development has the advantage that it is possible to achieve a particularly effective heat dissipation from the at least one light source.

It is a development that the at least one light source has at least one semiconductor light source. Preferably, the at least one semiconductor light source comprises at least one light-emitting diode. If several LEDs are present, they can be lit in the same color or in different colors. A color may be monochrome (e.g., red, green, blue, etc.) or multichrome (e.g., white). The light emitted by the at least one light-emitting diode can also be an infrared light (IR LED) or an ultraviolet light (UV LED). Several light emitting diodes can produce a mixed light; e.g. a white mixed light. The at least one light-emitting diode may contain at least one wavelength-converting phosphor (conversion LED). The phosphor may alternatively or additionally be arranged remotely from the light-emitting diode (often also referred to as "remote phosphor" arrangement). The at least one light-emitting diode can be in the form of at least one individually housed light-emitting diode or in the form of at least one LED chip. Several LED chips can be mounted on a common substrate ("submount"). The at least one light emitting diode may be equipped with at least one own and / or common optics for beam guidance, e.g. at least one Fresnel lens, collimator, and so on. Instead of or in addition to inorganic light emitting diodes, e.g. based on InGaN or AlInGaP, organic LEDs (OLEDs, for example polymer OLEDs) can generally also be used. Alternatively, the at least one semiconductor light source may be e.g. have at least one diode laser.

The substrate may additionally or alternatively be designed as a substrate or carrier for at least one electronic or electrical component.

For this purpose, the substrate may for example have placement locations for the at least one electronic or electrical component. This development has the advantage that it is possible to achieve a particularly effective heat dissipation from the at least one light source. The electronic or electrical component may for example be an SMD component.

The object is also achieved by a lighting device, comprising at least one substrate as described above, on which at least one light source, in particular semiconductor light source, is arranged.

The lighting device may be, for example, a light module (also referred to as a light engine), a lamp or a lamp.

The object is also achieved by a method for producing a substrate as described above, the method having at least the following steps: (a) producing at least one green body with at least one region, in particular layer, of ceramic starting material, in particular ceramic powder, and at least one Area, in particular layer, of cermet starting material, in particular cermet powder; and (b) sintering the green body.

The method can be designed analogously to the device and has the same advantages.

Thus, steps (a) and (b) may be carried out separately (e.g., in pressureless sintering), or they may be carried out simultaneously (e.g., by hot isostatic pressing).

The above-described characteristics, features, and advantages of this invention, as well as the manner in which they will be achieved, will become clearer and more clearly understood in connection with the following schematic description of exemplary embodiments which will be described in detail in conjunction with the drawings. In this case, the same or equivalent elements may be provided with the same reference numerals for clarity.

1 shows a sectional view in sectional view of a snapshot of a production of a substrate according to a first embodiment by hot isostatic pressing;

2 shows a sectional view in sectional view of a lighting device having the substrate according to the first embodiment; and

3 shows a sectional view in sectional view of a section of a further lighting device, which has a substrate according to a second embodiment;

4 shows a plan view of a section of yet another lighting device, which has a substrate according to a third embodiment;

5 shows a cross section of the lighting device 4 ; and

6 shows another cross section of the lighting device 4 ,

1 shows a sectional view in sectional view of a snapshot of a production of a substrate 11 by hot isostatic pressing, HIP (so-called "hip"). A corresponding HIP apparatus has a housing G or die which is open on the upper side and underside, into which first a lower-side first punch Su is introduced. The first stamp Su has on its free side F recesses or recesses P.

For producing the substrate 11 First, the recesses P are filled with cermet powder C1. Then, ceramic powder K is filled in the housing G. On the ceramic powder K, a layer of cermet powder C2 is applied. The cermet powder C1 and the cermet powder C2 may be the same or different powders, eg different in their starting materials and / or in their proportions.

Subsequently, a second punch So is introduced into the housing G on the upper side. To hip the two stamps Su and So are moved towards each other, as indicated by the arrows. Also, the powders K, C1 and C2 are heated to the extent that they can sinter. Overall, the powders K, C1 and C2 are thereby pressed together isostatically, whereby they form, for example, a green body, and at the same time or offset in time so far heated that they become a finished substrate 11 sinter.

2 shows a lighting device in the form of a first LED lighting module M1, which is the finished substrate 11 used. The substrate 11 has on its front surface or front side V a plurality of first cermet portions 12 resulting from the sintered cermet powder C1. The subareas 12 correspond in shape to the recesses P of the lower punch Su serving as negative patterns. The cermet sections 12 are integral on a ceramic section 13 made of sintered, electrically insulating ceramic, eg alumina. They run completely superficially, that is, that they are not completely over their length of the ceramic portion 13 but are exposed to the front.

On a back surface or back side R of the substrate 11 is located, integral with the ceramic section 13 connected, a sheet-shaped second cermet portion 14 formed from the sintered cermet powder C2.

During the ceramic section 13 has a high mechanical strength and the front side V and the back side R of the substrate 11 electrically insulated from each other, can at the cermet sections 12 and 14 simply metallic bodies are attached.

For example, here are the first cermet sections 12 electrically conductive and thus serve as tracks for LEDs L, of which a single LED L is shown here. The LED L has two lower-side contact surfaces B, which directly on the two electrically separate first cermet portions 12 can be applied, for example by soldering, for example in a reflow oven. It is advantageous that the sintering temperatures, which the substrate 11 is usually far higher than temperatures for soldering, leaving the substrate 11 Soldering can easily withstand. Thus, the substrate can 11 also be used for surface mounting.

The second cermet portion C2, which may be electrically conductive or non-conductive, is connected in a planar manner to a metallic body in the form of a heat sink H, by means of soldering, welding or other metal-metal connection methods. The heat sink H has been prefabricated here as a separate component. This allows a low heat transfer resistance between the substrate 11 and the heat sink H and thus also a high heat output from the LED L on the heat sink H. The heat sink H may for example consist of aluminum.

3 shows a section of a further lighting device in the form of a second LED lighting module M2, which is a substrate 21 according to a second embodiment. The substrate 21 has a plate-like basic shape, with a plate-shaped cermet portion on the back 24 integral with a plate-shaped ceramic section 23 connected is. The back cermet section 24 is used to attach a heat sink H2.

At the front V of the substrate 21 LEDs L are attached, but which are not like the substrate 11 are connected via superficially running conductor tracks. Rather, now run as a conductor tracks or connecting conductors, electrically conductive cermet portions 22 from the front side V of the substrate 21 which also a front of the ceramic section 23 corresponds, perpendicular to the ceramic section 23 into it, to the point of contact with an associated metal line 25 , The electrically conductive cermet sections 22 So now serve an electrical connection between the front side V and in the ceramic part 23 buried metal lines 25 , As a result, the front side V of the second LED lighting module M2 can, after the LEDs L have been placed, be placed on associated front end faces of the cermet sections 22 designed to be safe to touch.

The metal pipes 25 For example, metal bodies inserted in the ceramic powder K (eg, a metal wire, a metal strip, or another insert) or by incorporating traces of sinterable metal powder into the ceramic powder K can be produced. The electrically conductive cermet sections 22 can the metal lines 25 encompass in particular encompass, in particular encircling, which allows a particularly secure electrical contact and mechanical fixation.

4 shows a plan view of a section of yet another lighting device in the form of a third LED lighting module M3, which is a substrate 31 according to a third embodiment.

The substrate 31 is now honeycomb configured with arranged in a regular pattern hexagonal recesses W. The shown front side V consists predominantly of an electrically conductive cermet section 32 which, however, has several open separation points 35 having. The separation points 35 can as simple gaps 36 be formed, which up to the underlying, electrically non-conductive or electrically insulating ceramic portion 33 rich, as well as on average AA in 5 shown. Additionally or alternatively, the separation points 35 by an electrically insulating insulator element 37 be filled, which is a preparation of the separation points 35 like on average BB in 6 shown. On the separation points 35 or to the subsequent cermet sections 32 like LEDs L be applied contacting. The honeycomb cermet section 32 serves as a track system, in particular not bridged by LEDs L separation points 35 can serve a control or expression of a current flow.

As in 5 and 6 shown at the back of the substrate 31 More precisely, on the back cermet section 34 , a honeycomb radiator in plan view 39 at. The heat sink 39 However, now is not as a separately produced and subsequently to the cermet section 34 mounted heat sink formed, but as integral to the substrate 31 subsequent heat sink. For this purpose, for example, in the production of metal powder, for example comprising aluminum or copper, on or below that for the production of the back cermet portion 34 existing cermet powder C2 are arranged to be filled eg in a corresponding die or housing G.

In particular for this case, it may be advantageous for a cermet subarea, here: the backside cermet subarea 34 is a gradient range. The cermet section 34 has two sub-areas stacked on top of each other 34a and 34b which differ in their proportions of metal and ceramic. And that points to the ceramic section 33 adjacent cermet subrange 34a a higher ceramic content than the integral to the heat sink 39 subsequent cermet subrange 34b ,

Although the invention has been further illustrated and described in detail by the illustrated embodiments, the invention is not so limited and other variations can be derived therefrom by those skilled in the art without departing from the scope of the invention.

Thus, instead of or in addition to the LEDs, electronic and / or electrical components can also be fastened to the substrate.

In general, features of the various embodiments may be used additively or alternatively. For example, the cermet portion contacting the LEDs may also be raised for the lighting device M2 from the ceramic subregion.

Generally, "on", "an", etc. may be taken to mean a singular or a plurality, in particular in the sense of "at least one" or "one or more" etc., unless this is explicitly excluded, e.g. by the expression "exactly one", etc.

Also, a number may include exactly the specified number as well as a usual tolerance range, as long as this is not explicitly excluded.

LIST OF REFERENCE NUMBERS

11

substratum

12

first cermet subarea

13

Ceramic portion

14

second cermet subarea

21

substratum

22

Cermet portion

23

plate-shaped ceramic section

24

plate-shaped cermet portion

25

metal line

31

substratum

32

Cermet portion

33

Ceramic portion

34

Cermet portion

34a

Cermet subregion

34b

Cermet subregion

35

separation point

36

gap

39

heatsink

37

insulator element

C1, C2

cermet

B

contact area

F

free page

G

casing

H

heatsink

H2

heatsink

K

ceramic powder

L

LED

M1

first LED light module

M2

second LED light module

M3

third LED light module

P

return

R

back

Su

first stamp

So

second stamp

V

front

W

recess

Claims (15)

Substrate ( 11 ; 21 ; 31 ) for a lighting device (M1; M2; M3), wherein the substrate ( 11 ; 21 ; 31 ) at least one ceramic subregion ( 13 ; 23 ; 33 ) of electrically insulating ceramics and at least one cermet subregion ( 12 . 14 ; 22 . 24 ; 32 . 34 . 34a . 34b ) having. Substrate ( 11 ; 21 ; 31 ) according to claim 1, wherein the at least one cermet subregion ( 12 . 14 ; 22 . 24 ; 32 . 34 . 34a . 34b ) a part of a surface of the substrate ( 11 ; 21 ; 31 ). Substrate ( 11 ; 21 ; 31 ) according to claim 2, wherein the substrate ( 11 ; 21 ; 31 ) a ceramic subregion ( 13 ; 23 ; 33 ) has a front side and a rear side, and at least one cermet subregion (at the front side and / or at the rear side) 12 . 14 ; 24 ; 32 . 34 . 34a . 34b ). Substrate ( 11 ; 21 ; 31 ) according to claim 3, wherein at least its front side (V) has at least one electrically conductive cermet subregion (at least partially superficial) ( 12 ; 22 ; 32 Has) as an electrical conductor. Substrate ( 11 ; 31 ) according to claim 4, wherein the track ( 12 ; 32 ) is completely superficial. Substrate ( 21 ) according to claim 4, wherein the track ( 22 ) partially in the ceramic portion ( 23 ) runs. Substrate ( 11 ; 21 ; 31 ) according to one of the preceding claims, wherein at least one cermet subregion ( 12 . 14 ; 22 . 24 ; 32 . 34 . 34b ) at least one metallic body (B, L, H; 25 , H2; 39 ). Substrate ( 11 ; 21 ) according to claim 7, wherein at least one metallic body (B, L, H; H2) is manufactured separately and thereafter by means of a metal joining process on at least one cermet subregion (B, L, H; 12 . 14 ; 22 . 24 ; 32 ) is attached body. Substrate ( 31 ) according to one of claims 7 to 8, wherein at least one metallic body ( 39 ) to the cermet subsection ( 34 . 34b ) is an integral subsequent metallic body. Substrate ( 11 ; 21 ; 31 ) according to any one of claims 7 to 9, wherein at least one metallic body (H; H2; 39 ) is a heat sink. Substrate ( 11 ; 21 ) according to one of claims 7 to 10, wherein at least one metallic body ( 25 ) at least partially in the ceramic subregion ( 23 ) and at least one associated cermet subregion ( 22 ) is encompassed. Substrate ( 31 ) according to one of the preceding claims, wherein at least one cermet subregion ( 34 ) a gradient region ( 34a . 34b ). Substrate ( 11 ; 21 ; 31 ) according to any one of the preceding claims, wherein the substrate ( 11 ; 21 ; 31 ) has been produced by means of a method which comprises at least the following steps: - producing a green body (C1, C2, K), wherein the green body (C1, C2, K) comprises at least one area of ceramic starting material (K) and at least one area made of cermet starting material (C1, C2); and sintering the green body to the substrate ( 11 ; 21 ; 31 ). Substrate ( 31 ) according to claim 13, wherein the green body also has at least one metal region, in particular sinterable metal. Method for producing a substrate ( 11 ; 21 ; 31 ) according to claim 14, wherein the method comprises at least: - producing at least one green body (C1, C2, K) with at least one region of ceramic starting material (K) and at least one region of cermet starting material (C1, C2); and sintering the green body (C1, C2, K).

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