Heat sink and light emitting diode lamp

1. A heat sink used for dissipating heat generated by a light emitting diode (LED) module, comprising:

an inner piece having a side surface and having a body that from a round, flat base narrows to a round, flat tip, wherein the LED module comprising a current control circuit and a LED light source is disposed on the round, flat base; and

a hollow outer piece disposed around the inner piece and having an inner side surface, wherein the side surface of the inner piece tightly fits the inner side surface of the outer piece so as to rivet together the outer piece and form an interface, and an area ratio of the interface and the side surface of the inner piece is between 0.6 and 0.95.

2. The heat sink as claimed in claim 1 , wherein a material constituting the inner piece comprises copper, aluminium, ceramic or aluminum nitride (AlN).

3. The heat sink as claimed in claim 1 , wherein a material constituting the outer piece comprises aluminium.

4. The heat sink as claimed in claim 1 , wherein a thickness of the inner piece is between 1 millimeter and 10 millimeters.

5. The heat sink as claimed in claim 1 , wherein a longitudinal length of the interface is between 0.6 millimeters and 9.5 millimeters.

6. A light emitting diode (LED) lamp, comprising:

a heat sink, comprises:

an inner piece having an upper surface, a lower surface opposite to the upper surface and a side surface connected to the upper surface and the lower surface; and

an outer piece disposed around the inner piece and having an inner side surface, wherein the side surface of the inner piece is riveted to the inner side surface of the outer piece to form an interface, an area ratio of the interface and the side surface of the inner piece is between 0.6 and 0.95;

a current control circuit disposed on the inner piece of the heat sink and located in the upper surface;

a LED light source disposed on the current control circuit and electrically connected to the current control circuit; and

a connecting portion disposed on inner piece of the heat sink and located in the lower surfaces;

wherein the upper surface of the inner piece and an upper portion of the inner side surface of the outer piece form a first accommodating space, and the current control circuit and the LED light source are disposed inside the first accommodating space, and wherein the lower surface of the inner piece and a lower portion of the inner side surface of the outer piece form a second accommodating space, and the connecting portion is disposed inside the second accommodating space.

7. The LED lamp as claimed in claim 6 , wherein a material constituting the inner piece comprises copper, aluminium, ceramic or aluminum nitride (AlN).

8. The LED lamp as claimed in claim 6 , wherein a material constituting the outer piece comprises aluminium.

9. The LED lamp as claimed in claim 6 , wherein a thickness of the inner piece is between 1 millimeter and 10 millimeters.

10. The LED lamp as claimed in claim 6 , wherein a longitudinal length of the interface is between 0.6 millimeters and 9.5 millimeters.

11. The LED lamp as claimed in claim 6 , wherein the inner piece of the heat sink has a round shape.

12. The LED lamp as claimed in claim 6 , wherein the outer piece of the heat sink comprises a hollow structure.

13. The LED lamp as claimed in claim 6 , wherein the current control circuit comprises a printed circuit board.

14. The LED lamp as claimed in claim 6 , wherein the LED light source comprises an LED package.

15. The LED lamp as claimed in claim 6 , further comprises a lampshade, connected to the heat sink.