Devices Having Anisotropic Conductivity Heatsinks, and Methods of Making Thereof

• US 20120206882A1
• Filed: 03/24/2011
• Published: 08/16/2012
• Est. Priority Date: 02/14/2011
• Status: Active Grant

• Current Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Original Assignee: Futurewei Technologies Incorporated (Huawei Investment & Holding Co., Ltd.)
• Inventors: Mohammed, Anwar, Zhao, Renzhe
• Granted Patent: US 8,537,553 B2
• Time in Patent Office: Days
• US Class Current: 361/710
• CPC Class Codes: H01L 23/3675 characterised by the shape of the housing
• CPC Class Codes: H01L 23/3677 Wire-like or pin-like cooling fins or heat sinks
• CPC Class Codes: H01L 23/373 Cooling facilitated by selection of materials for the device or materials for thermal expansion adaptation, e.g. carbon
• CPC Class Codes: H01L 23/3735 Laminates or multilayers, e.g. direct bond copper ceramic substrates
• CPC Class Codes: H01L 2924/00 Indexing scheme for arrangements or methods for connecting or disconnecting semiconductor or solid-state bodies as covered by H01L24/00
• CPC Class Codes: H01L 2924/0002 Not covered by any one of groups H01L24/00, H01L24/00 and H01L2224/00

Abstract

In accordance with an embodiment of the present invention, a device includes a circuit board with a thermally conductive core layer and a chip disposed over the circuit board. The device further includes a heat sink disposed over the chip. The thermal conductivity of the heat sink along a first direction is larger than a thermal conductivity along a second direction. The first direction is perpendicular to the second direction. The heat sink is thermally coupled to the thermally conductive core layer.

Claims

1. A device comprising:

a circuit board having a thermally conductive core layer;

a chip disposed over the circuit board; and

a heat sink disposed over the chip, wherein a thermal conductivity of the heat sink along a first direction is larger than a thermal conductivity along a second direction, the first direction being perpendicular to the second direction, and wherein the heat sink is thermally coupled to the thermally conductive core layer.

2. The device of claim 1, further comprising:

a first heat transferring block disposed on a bottom surface of the heat sink, the first heat transferring block disposed between an edge of the heat sink and the circuit board; and

a first connecting member disposed in the circuit board and thermally coupled between the first heat transferring block and the thermally conductive core layer, wherein the heat sink is thermally coupled to the thermally conductive core layer through the first heat transferring block and the first connecting member.

3. The device of claim 2, further comprising:

a second heat transferring block disposed on the bottom surface of the heat sink, the second heat transferring block disposed between the first heat transferring block and the chip; and

a second connecting member disposed in the circuit board and thermally coupled between the second heat transferring block and the thermally conductive core layer.

4. The device of claim 2, further comprising a second connecting member thermally coupled between the first heat transferring block and the thermally conductive core layer.

5. The device of claim 1, wherein the heat sink comprises graphene fibers oriented along the first direction.

6. The device of claim 1, wherein the heat sink comprises through substrate structures.

7. The device of claim 1, further comprising a plurality of bottom fins disposed on a bottom surface of the heat sink, the bottom surface of the heat sink being closer to the chip than an opposite top surface of the heat sink.

8. The device of claim 7, further comprising a plurality of auxiliary fins coupled to the plurality of bottom fins, the plurality of auxiliary fins oriented in a different direction than the plurality of bottom fins.

9. The device of claim 1, further comprising a plurality of top fins disposed on a top surface of the heat sink, the top surface of the heat sink being farther from the chip than an opposite bottom surface of the heat sink.

10. The device of claim 1, further comprising a thermal interface material layer disposed between the chip and the heat sink.

11. The device of claim 1, wherein the thermally conductive core layer is disposed around a central portion of the circuit board.

12. The device of claim 1, wherein the heat sink is curved.

13. The device of claim 1, wherein the heat sink is coupled to the thermally conductive core layer through at least two conductive thermal paths.

14. The device of claim 1, further comprising

an isotropic heat sink disposed over the heat sink;

and

a plurality of top fins disposed over the isotropic heat sink.

15. The device of claim 14, wherein the isotropic heat sink comprises aluminum.

16. The device of claim 1, wherein the thermal conductivity of the heat sink along a first direction is about 400 W/mK to about 1200 W/mK, and wherein the thermal conductivity of the heat sink along the second direction is about 20 W/mK to about 100 W/mK.

17. A printed circuit board assembly comprising:

a substrate having a thermally conductive core layer;

a semiconductor device disposed over the substrate; and

a heat sink having an anisotropic thermal conductivity disposed over the semiconductor device, wherein a bottom surface of the heat sink is thermally coupled to the thermally conductive core layer, the bottom surface of the heat sink being closer to the semiconductor device than an opposite top surface of the heat sink.

18. The printed circuit board assembly of claim 17, further comprising:

a heat transferring block disposed between an edge of the heat sink and the substrate on the bottom surface of the heat sink; and

a connecting member disposed in the substrate and thermally coupled between the heat transferring block and the thermally conductive core layer.

19. The printed circuit board assembly of claim 17, wherein the heat sink comprises graphene fibers.

20. The printed circuit board assembly of claim 17, further comprising a plurality of bottom fins disposed on the bottom surface of the heat sink.

21. The printed circuit board assembly of claim 20, further comprising a plurality of auxiliary fins coupled to the plurality of bottom fins, the plurality of auxiliary fins oriented in a different direction than the plurality of bottom fins.

22. A method for forming a printed circuit board assembly, the method comprising:

placing a semiconductor device over a substrate, the substrate having a thermally conductive core layer;

placing a heat sink having an anisotropic thermal conductivity over the semiconductor device; and

thermally coupling a bottom surface of the heat sink to the thermally conductive core layer, the bottom surface of the heat sink being closer to the semiconductor device than an opposite top surface of the heat sink.

23. The method of claim 22, wherein thermally coupling a bottom surface of the heat sink to the thermally conductive core layer comprises:

attaching a top surface of a heat transferring block to an edge of the heat sink; and

attaching an opposite bottom surface of the heat transferring block to a connecting member in the substrate, the connecting member being thermally coupled to the thermally conductive core layer.

24. The method of claim 22, wherein the heat sink comprises graphene fibers.

25. The method of claim 22, further comprising thermally coupling a plurality of bottom fins to the bottom surface of the heat sink.