COUNTERFLOW MICROCHANNEL COOLER FOR INTEGRATED CIRCUITS
A plurality of channels are formed in a base, e.g., a substrate of an integrated circuit, each channel extending between edges of the base. Two pairs of manifolds are provided, the first pair communicating with a first group of channels and the second pair communicating with a second group of channels, the first group of channels and the first pair of plena isolated from the second group of channels and the second pair of plena. Each of the pairs of manifolds includes multiple branches coupled to the channels and a common plenum. Cooling fluid is injected into the channels from different sides of the base, causing fluid to flow in different directions in the two groups of channels, the channels in thermal contact with the integrated circuit.
1. Field of the Invention
This invention relates to cooling integrated circuits and more particularly to microchannel coolers for integrated circuits.
2. Description of the Related Art
Much of the power consumed by a modern integrated circuit (IC) during operation is dissipated as heat, increasing the temperature of the IC and altering its properties. For example, silicon switching speed is slower when hot. Additionally, reliability is reduced as temperature increases. If the temperature is sufficiently high, irreversible damage occurs. To remove heat as quickly as possible, several approaches have been used in the art. These generally involve mounting heat dissipaters, such as heat sinks, near the IC package.
As can be seen, this integrated circuit assembly relies on conduction through the thermal interface materials and the package to remove heat from ICs. Since many ICs typically have hotspots, i.e., they are not uniformly heated, that non-uniformity may be transferred largely unchanged through the package to the heat exchanger.
Referring to
One approach to address that problem, shown in
A vertical section close to the edge of side 208, and looking into the IC, is shown in
The stacked channel approach shown in
In view of the approaches described above, improved cooling approaches are desirable to improve reliability and performance.
SUMMARYIn one embodiment, an apparatus includes a plurality of channels formed in a base, each channel having first and second ends. The channels are substantially parallel to a surface of the base and run from a first to a second edge of the base. The apparatus includes a first pair of manifolds, each manifold of the first pair having a plurality of branches and a plenum connected to the branches. A first manifold of the first pair is disposed at the first edge and a second manifold of the first pair disposed at the second edge of the base. The first pair of manifolds are in fluid communication with a first group of the channels. The apparatus includes a second pair of manifolds, each manifold of the second pair having a plurality of branches and a plenum connected to the branches. A first manifold of the second pair is disposed at the first edge and a second manifold of the second pair is disposed at the second edge of the base. The second pair of manifolds are in fluid communication with a second group of channels and isolated from the first pair of manifolds and the first group of channels. The one or more channels of the first group are substantially thermally non-blocking with respect to the one or more channels of the second group of channels in a direction towards a heat source.
In an embodiment, the channels in the first and second group are configured to carry fluid in opposite directions. In an embodiment, the channels of the first group are interleaved with channels of the second group.
In another embodiment, a method is provided that includes causing fluid to flow in a first direction from an inlet end to an outlet end in a first plurality of channels formed in a base, the channels being substantially parallel to a surface of the base and running from a first to a second edge of the base, the first direction being from the first to the second edge of the base; and causing fluid to flow in a second direction from an inlet end to an outlet end in a second plurality of channels formed in the base, the second plurality of channels substantially parallel to the surface of the base and running from the first to the second edge of the base, the second direction being from the second to the first edge of the base, and wherein the one or more channels of the first group are substantially thermally non-blocking with respect to the one or more channels of the second group in a direction towards a heat source.
In still another embodiment, a process for making an apparatus is provided. The process includes disposing one manifold of a first pair of manifolds and one manifold of a second pair of manifolds along a first edge of a base, the base having a first and second group of channels extending from a first to a second edge of the base. A second manifold of the first pair and a second manifold of the second pair are disposed along a second edge of the base, the pairs of manifolds in fluid communication with respective groups of channels. The manifolds are hermetically sealed to the edges of the base along which they are disposed, maintaining fluid communication between first and second pairs of manifolds and respective groups of channels.
The present invention may be better understood, and its numerous objects, features, and advantages made apparent to those skilled in the art by referencing the accompanying drawings. As is customary in the art, sketches such as those shown in the figures are not to scale, with some features exaggerated to better point out relevant relationships between them.
The use of the same reference symbols in different drawings indicates similar or identical items.
DESCRIPTION OF THE PREFERRED EMBODIMENT(S)In order to address the limitations of the stacked channel arrangement shown in
In the embodiment of
As stated before, in order to address the limitations of the stacked channel arrangement, a counterflow microchannel approach is utilized in various embodiments of the invention described herein.
In an embodiment of the invention, the base 332 is a substrate of a semiconductor device with the active area of the semiconductor displaced from the location of the microchannels. Thus, the microchannels are formed on the backside of the substrate. In one embodiment, the substrate is silicon and the integrated circuit may be formed by any of a number of well known integrated circuit manufacturing techniques. In the embodiment of the microchannels shown in
Referring to
Referring now to
Referring now to
Referring again to
The channels may be formed monolithically in the base 332 by scribing, etching techniques such as those used for micro-electro-mechanical structures (MEMS), use of a sacrificial filler material such as in lost wax casting, growing layers over embedded channels or other methods. Capping with a separate material may also form the channels 330, 350. Channels 330 and 350 need not alternate in a one-to-one fashion as shown. For example, two channels 330 may be interleaved between two channels 350, or some other arrangement. However, in a preferred embodiment, the channels 330 and 350 are interleaved. Further, the pitch (and depth) of the channels is much less than the distance to the heat source. In a typical high power microprocessor, the distance from the microchannels to the heat source on the active side of the semiconductor is determined by semiconductor thickness, approximately 0.8 mm. More generally, the substrate may have a thickness, e.g., of 0.5 to 1.5 mm, while the pitch of the channels may range, e.g., from several micrometers to tens of micrometers. Pitch is defined as the lateral size of the channels plus the gap between them. Channel depth may have similar or smaller dimensions than pitch. Having the pitch (and depth) of the channels be much less than the distance to the heat source allows the heat source to see the warm and cold adjacent channels as a dipole and provides better heat management for the integrated circuit.
The housings 334 and 354 shown in
Full circles in
In the example depicted in FIGS. 4B and 6A-6C, with alternating shallow 350 and deep 330 channels, vias 356 and 336 may be separated by depth. In the more general case, vias 336, 356 may be separated, and so channels 330, 350 isolated by placement of the branches 372, 378. Note that in
Referring back to
Referring to
Manifold configurations may be modified or constructed differently to accommodate alternate fluid flow patterns.
While the preferred embodiments of the invention have been illustrated and described, it will be clear that the invention is not limited to these embodiments only. Numerous modifications, changes, variations, substitutions and equivalents will be apparent to those skilled in the art without departing from the spirit and scope of the invention as described in the claims. Various embodiments of techniques for managing thermal loads in integrated circuits have been described. The description of the invention set forth herein is illustrative, and is not intended to limit the scope of the invention as set forth in the following claims. For example, although the present invention has been described primarily with reference to cooling an IC, it also may be used to heat or maintain a constant temperature in an IC used at cryogenic temperatures. Other variations and modifications of the embodiments disclosed herein may be made based on the description set forth herein, without departing from the scope of the invention as set forth in the following claims.
Claims
1. An apparatus comprising:
- a plurality of channels formed in a base, each channel having first and second ends, the channels substantially parallel to a surface of the base and running from a first to a second edge of the base;
- a first pair of manifolds, each manifold of the first pair having a plurality of branches and a plenum connected to the branches, a first manifold of the first pair disposed at the first edge and a second manifold of the first pair disposed at the second edge of the base, the first pair of manifolds in fluid communication with a first group of the channels;
- a second pair of manifolds, each manifold of the second pair having a plurality of branches and a plenum connected to the branches, a first manifold of the second pair disposed at the first edge and a second manifold of the second pair disposed at the second edge of the base, the second pair of manifolds in fluid communication with a second group of channels and isolated from the first pair of manifolds and the first group of channels; and
- wherein the one or more channels of the first group are substantially thermally non-blocking with respect to the one or more channels of the second group of channels in a direction towards a heat source.
2. The apparatus as recited in claim 1 wherein at least a portion of each of the channels in the first group and at least a portion of each of the channels in the second group are in a plane parallel to the surface of the base.
3. The apparatus as recited in claim 1 wherein the channels in the first and second group are configured to carry fluid in opposite directions.
4. The apparatus as recited in claim 1 wherein the channels of the first group are interleaved with channels of the second group.
5. The apparatus as recited in claim 1 wherein the base is a substrate of an integrated circuit and the channels are formed in a backside of the substrate.
6. The apparatus of claim 1, wherein the base is attached to a substrate of the integrated circuit.
7. The apparatus as recited in claim 5 wherein channel pitch in the base is between approximately 1 and 30 micrometers and a thickness of the substrate is approximately 0.5 to 1.5 mm.
8. The apparatus as recited in claim 1, wherein channels of the first and second groups have equal aspect ratios.
9. The apparatus as recited in claim 1, wherein channels of the first and second groups have equal cross-sectional areas.
10. The apparatus as recited in claim 1, wherein at least one of the channels has different cross-sectional areas at respective different locations in the at least one channel.
11. The apparatus as recited in claim 1, wherein channels of the first and second groups have cross-sectional areas that range between approximately 30 square microns to 3000 square microns.
12. The apparatus as recited in claim 1, further comprising:
- first and second housings disposed at respective edges of the base, each housing hermetically sealing the manifolds disposed at respective edges of the base.
13. The apparatus as recited in claim 12, wherein the first housing has a first group of vias at a first height to fluidly connect the first manifold of the first pair of manifolds to the first group of channels and a second group of vias at a second height to fluidly connect the first manifold of the second pair of manifolds to the second group of channels.
14. The apparatus as recited in claim 13, wherein the second housing has a first group of vias at the first height to fluidly connect the second manifold of the first pair of manifolds to the first group of channels and a second group of vias at the second height to fluidly connect the second manifold of the second pair of manifolds to the second group of channels.
15. The apparatus as recited in claim 1, further comprising first and second fluid conduits connected to the first and second pair of manifolds.
16. The apparatus as recited in claim 15, further comprising a pump operable to flow a fluid through one or more of the conduits.
17. The apparatus as recited in claim 16, further comprising first and second housings disposed at respective edges of the base, each housing hermetically sealing the manifolds disposed at respective edges of the base.
18. The apparatus of claim 16, further comprising a heat exchanger, at least a portion of each of the first and second conduits in thermal contact with the heat exchanger.
19. A method of managing heat in an integrated circuit comprising:
- causing fluid to flow in a first direction from an inlet end to an outlet end in a first plurality of channels formed in a base, the channels being substantially parallel to a surface of the base and running from a first to a second edge of the base, the first direction being from the first to the second edge of the base; and
- causing fluid to flow in a second direction from an inlet end to an outlet end in a second plurality of channels formed in the base, the second plurality of channels substantially parallel to the surface of the base and running from the first to the second edge of the base, the second direction being from the second to the first edge of the base, and wherein the one or more channels of the first group are substantially thermally non-blocking with respect to the one or more channels of the second group in a direction towards a heat source.
20. The method as recited in claim 19 further comprising,
- feeding cold fluid from a first manifold disposed at the first edge of the base to the inlet ends of the first plurality of channels; and
- exhausting warmed fluid to a second manifold disposed at the second edge of the base from the outlet ends of the first plurality of channels;
- feeding cold fluid from a third manifold disposed at the second edge of the base to the inlet ends of the second plurality of channels; and
- exhausting warmed fluid to a fourth manifold disposed at the first edge of the base from the outlet ends of the second plurality of channel.
21. The method as recited in claim 19 wherein the base is a substrate of the integrated circuit.
22. The method of claim 19, further comprising isolating the fluid in the first plurality of channels from the fluid in the second plurality of channels.
23. The method of claim 19, further comprising:
- causing the fluid from the first plurality of channels to flow from the second manifold into a first fluid conduit; and
- causing the fluid from the second plurality of channels to flow from the fourth manifold into a second fluid conduit.
24. The method of claim 23, further comprising:
- transferring heat between the fluid in at least one of the first and second conduits and a heat exchanger along the path of the at least one of the conduits.
25. A process for making an apparatus, the process comprising:
- disposing one manifold of a first pair of manifolds and one manifold of a second pair of manifolds along a first edge of a base, the base having a first and second group of channels extending from a first to a second edge of the base;
- disposing a second manifold of the first pair and a second manifold of the second pair along a second edge of the base, the pairs of manifolds in fluid communication with respective groups of channels; and
- hermetically sealing the manifolds to the edges of the base along which they are disposed, maintaining fluid communication between first and second pairs of manifolds and respective groups of channels.
26. The process as recited in claim 25, wherein the base is a back side of a substrate of an integrated circuit.
27. The process as recited in claim 25, wherein the channels of the first and second groups have equal aspect ratios.
28. The process as recited in claim 25, wherein the channels of the first and second groups have equal cross-sectional areas.
29. The process as recited in claim 25, wherein
- channels of the first and second groups have cross-sectional areas that range between approximately 30 square microns to 3000 square microns.
Type: Application
Filed: Jun 1, 2007
Publication Date: Dec 4, 2008
Inventor: Richard C. Blish, II (Saratoga, CA)
Application Number: 11/756,749
International Classification: H05K 7/20 (20060101); H05K 3/00 (20060101);