Heat spreaders fabricated from metal nanoparticles

Patent metadata

Field	Value
Publication number	US-2016265858-A1
Application number	US-201615065760-A
Country	US
Kind code	A1
Filing date	Mar 9, 2016
Priority date	Mar 11, 2015
Publication date	Sep 15, 2016
Grant date	—

Abstract

Heat spreaders can help promote heat distribution at the surface of a heat sink. However, overly isotropic or anisotropic heat conduction through heat spreaders can limit their effectiveness. Heat spreaders providing for lateral distribution of heat can include a tapered structure containing a metal-diamond composite. The metal-diamond composite includes a continuous metallic phase and a plurality of micron-scale diamond particles located in spaced apart regions of the continuous metallic phase. An interlayer containing the continuous metallic phase but lacking micron-scale diamond particles is disposed between each of the spaced apart regions, and the metal-diamond composite increases in lateral size in a direction of increased tapering. Heat spreaders can be formed by disposing a first mixture containing micron-scale diamond particles and metal nanoparticles in first regions that are vertically spaced apart from each other, and at least partially fusing the metal nanoparticles to form a tapered structure.

First claim

What is claimed is the following:

1 . A heat spreader comprising:
a tapered structure comprising a metal-diamond composite;
wherein the metal-diamond composite comprises a continuous metallic phase and a plurality of micron-scale diamond particles located in spaced apart regions of the continuous metallic phase;
wherein an interlayer comprising the continuous metallic phase but lacking micron-scale diamond particles is disposed between each of the spaced apart regions; and
wherein the metal-diamond composite increases in lateral size in a direction of increased tapering.

2 . The heat spreader of claim 1 , wherein the plurality of micron-scale diamond particles range between about 200 microns and about 250 microns in size.

3 . The heat spreader of claim 1 , wherein the metal-diamond composite comprises about 40% to about 70% micron-scale diamond particles by volume.

4 . The heat spreader of claim 1 , wherein the tapered structure comprises a plurality of stepped tiers.

5 . The heat spreader of claim 1 , wherein the continuous metallic phase has a grain size of about 250 nm or less.

6 . The heat spreader of claim 1 , wherein the continuous metallic phase comprises copper.

7 . The heat spreader of claim 1 , wherein the continuous metallic phase further comprises a carbide-forming additive.

8 . The heat spreader of claim 1 , wherein the interlayers further comprise nanodiamond particles, a plurality of fibers, or any combination thereof disposed in the continuous metallic phase.

9 . The heat spreader of claim 8 , wherein the plurality of fibers are oriented laterally in the interlayers.

10 . The heat spreader of claim 8 , wherein the interlayers range between about 20 microns and about 500 microns in thickness.

11 . A system comprising:
a heat source; a heat sink; and a heat spreader extending between the heat source and the heat sink and bonded thereto;
wherein the heat spreader comprises:
a tapered structure comprising a metal-diamond composite;
wherein the metal-diamond composite comprises a continuous metallic phase and a plurality of micron-scale diamond particles located in spaced apart regions of the continuous metallic phase;
wherein an interlayer comprising the continuous metallic phase but lacking micron-scale diamond particles is disposed between each of the spaced apart regions; and
wherein the metal-diamond composite increases in lateral size from the heat source to the heat sink.

12 . The system of claim 11 , wherein the plurality of micron-scale diamond particles range between about 200 microns and about 250 microns in size.

13 . The system of claim 11 , wherein the metal-diamond composite comprises about 40% to about 70% micron-scale diamond particles by volume.

14 . The system of claim 11 , wherein the tapered structure comprises a plurality of stepped tiers.

15 . The system of claim 11 , wherein the continuous metallic phase comprises copper.

16 . The system of claim 11 , wherein the interlayers further comprise nanodiamond particles, a plurality of fibers, or any combination thereof disposed in the continuous metallic phase.

17 . The system of claim 16 , wherein the interlayers range between about 20 microns and about 500 microns in thickness.

18 . A method comprising:
disposing a first mixture comprising micron-scale diamond particles and metal nanoparticles in first regions that are vertically spaced apart from each other; disposing a second mixture comprising metal nanoparticles but lacking micron-scale diamond particles in second regions located between each of the first regions;
wherein the first regions increase progressively in lateral size; and
at least partially fusing the metal nanoparticles to form a tapered structure comprising a metal-diamond composite;
wherein the metal-diamond composite comprises a continuous metallic phase within the first regions and the second regions.

19 . The method of claim 18 , wherein disposing the first mixture and the second mixture comprises sequentially casting the first mixture and the second mixture into a mold in layers, and at least partially fusing the metal nanoparticles comprises hot pressing the layers in the mold.

20 . The method of claim 18 , further comprising:
bonding the tapered structure to a heat source and a heat sink.

Assignees

• Lockheed Corp

Inventors

• Zinn Alfred A
• Iyer Jyotsna
• Hsu Ike C

Classifications

• C22C26/00

  Alloys containing diamond {or cubic or wurtzitic boron nitride, fullerenes or carbon nanotubes} · CPC title

• B23K2103/50

  Inorganic materials other than metals or composite materials · CPC title

• B23K31/02 Primary

  relating to soldering or welding · CPC title

• B23K1/0012

  Brazing of heat exchangers · CPC title

• B23K2101/14

  Heat exchangers · CPC title