Illumination device comprising a substrate plate and a heat sink

1. An illumination device ( 1 ) comprising at least one substrate plate ( 2 ), at least one luminous element ( 3 ) arranged on a front side (A) of the substrate plate ( 2 ), and at least one heat sink ( 4 ) connected to a rear side (B) of the substrate plate ( 2 ) over a large area, wherein the coefficients of thermal expansion of substrate plate ( 2 ) and heat sink ( 4 ) differ at least by the factor 1.5, characterized in that the heat sink ( 4 ) has at least one recess ( 6 ) on its side facing the rear side (B) of the substrate plate ( 2 ).

2. The illumination device ( 1 ) as claimed in claim 1 , wherein at least two segments ( 8 ) of the heat sink ( 4 ) are provided which are completely separated from one another by at least one linear recess ( 6 ) in the connecting plane with respect to the substrate plate ( 2 ).

3. The illumination device ( 1 ) as claimed in claim 1 , characterized in that the heat sink ( 4 ) has at least two linear recesses ( 6 ).

4. The illumination device ( 1 ) as claimed in claim 1 , characterized in that at least two linear recesses ( 6 ) are parallel.

5. The illumination device ( 1 ) as claimed in claim 1 , characterized in that at least one linear recess ( 6 ) is formed in rectilinear fashion at least in sections.

6. The illumination device ( 1 ) as claimed in claim 3 , characterized in that at least two linear recesses ( 6 ) have at least one point of intersection.

7. The illumination device ( 1 ) as claimed in claim 2 , characterized in that the at least two segments ( 8 ) of the heat sink ( 4 ) which are completely separated from one another are connected to a common basic body ( 9 ).

8. The illumination device ( 1 ) as claimed in claim 2 , characterized in that at least one segment ( 8 ) of the heat sink ( 4 ) and the common basic body ( 9 ) are formed in one piece.

9. The illumination device ( 1 ) as claimed in claim 2 , characterized in that the linear dimensions of a segment ( 8 ) of the heat sink ( 4 ) in the connecting plane with respect to the substrate plate ( 2 ) independently of the measurement direction are less than 20 mm.

10. The illumination device ( 1 ) as claimed in claim 2 , characterized in that at least one of the segments ( 8 ) is connected to the basic body ( 9 ) by means of a mechanical connecting element.

11. The illumination device ( 1 ) as claimed in claim 2 , characterized in that at least one of the segments ( 8 ) is connected to the basic body ( 9 ) by means of an adhesive bonding connection ( 10 ).

12. The illumination device ( 1 ) as claimed in claim 2 , characterized in that at least one segment ( 8 ) of the heat sink ( 4 ) has a rectangular, in particular square, outer contour in the connecting plane with respect to the substrate plate ( 2 ).

13. The illumination device ( 1 ) as claimed in claim 2 , characterized in that at least one segment ( 8 ) of the heat sink ( 4 ) has an elliptical, outer contour in the connecting plane with respect to the substrate plate ( 2 ).

14. An illumination device ( 1 ) comprising at least one substrate plate ( 2 ), at least one luminous element ( 3 ) arranged on a front side (A) of the substrate plate ( 2 ), and at least one heat sink ( 4 ) connected, to a rear side (B) of the substrate plate ( 2 ) over a large area, wherein the coefficients of thermal expansion of substrate plate ( 2 ) and heat sink ( 4 ) differ at least by the factor 1.5, characterized in that at least one segment ( 6 ) of the heat sink ( 4 ) which is not connected to the substrate plate ( 2 ).

15. An illumination device ( 1 ) comprising at least one substrate plate ( 2 ), at least one luminous element ( 3 ) arranged on a front side (A) of the substrate plate ( 2 ), and at least one heat sink ( 4 ) connected to a rear side (B) of the substrate plate ( 2 ) over a large area, wherein the coefficients of thermal expansion of substrate plate ( 2 ) and heat sink ( 4 ) differ at least by the factor 1.5, characterized in that at least one segment ( 8 ) of the heat sink ( 4 ) is formed in approximately U-shaped fashion, wherein the opening ( 13 ) of the U is remote from the substrate plate ( 2 ).

16. An illumination device ( 1 ) comprising at least one substrate plate ( 2 ), at least one luminous element ( 3 ) arranged on a front side (A) of the substrate plate and at least one heat sink ( 4 ) connected, to a rear side (B) of the substrate plate ( 2 ) over a large area, wherein the coefficients of thermal expansion of substrate plate ( 2 ) and heat sink ( 4 ) differ at least by the factor 1.5, characterized in that the heat sink ( 4 ) is formed at least partly from bent sheet metal.

17. The illumination device ( 1 ) as claimed in claim 1 , characterized in that the heat sink ( 4 ) is formed substantially from aluminum and/or an aluminum alloy.

18. The illumination device ( 1 ) as claimed in claim 1 , characterized in that the heat sink ( 4 ) is formed substantially from copper and/or a copper alloy.

19. The illumination device ( 1 ) as claimed in claim 1 , characterized in that the substrate plate ( 2 ) is formed substantially from Al 2 O 3 and/or AIN.

20. The illumination device as claimed in claim 1 wherein

the substrate plate is a ceramic substrate plate;

the at least one luminous element is a light emitting diode(s);

the heat sink is metallic and is connected to the rear side by being adhesively bonded and/or soldered; and

the coefficient of thermal expansion differs by a factor greater than 2.

21. The illumination device ( 1 ) as claimed in claim 13 , characterized in that the elliptical outer contour in the connecting plane with respect to the substrate plate ( 2 ) is circular.