US20050263273A1 - Electroformed microchannel cooler and methods of making same - Google Patents

Abstract

An electroformed microchannel cooler for liquid cooling has an upper component and a lower component. Each component includes a sheet, a plurality of electroformed partition walls and a boundary wall electroformed outwardly of the plurality of partition walls. The partition and boundary walls of the upper component are attached to the boundary and partition walls of the lower part to provide a plurality of microchannels for flowing liquid through the cooler in a heat exchange relationship. One of the components has gates at each end opening into plenums inside the boundary walls. An alternate embodiment has a corrugated electroformed member attached to upper an lower sheets forming a plurality of parallel microchannels. Methods of making the electroformed microchannel coolers are also disclosed.

Description

FIELD OF THE INVENTION
• This invention relates to coolers and methods of making coolers.
BACKGROUND OF THE INVENTION
• The trend in integrated circuit (IC) design, particularly in central processing units (CPUs), is increased speed and circuit density. Increased speed and circuit density causes the IC or CPU to generate more heat. This raises a need for cooling because without sufficient cooling, the IC or CPU may run slower and degrade leading to a shortened life span. Moreover, such ICs and CPUs are being used in electronic devices, such as servers and portable computers, having housings that are getting smaller and smaller which exacerbates the cooling need.
• It is already known to use water or liquid cooling systems in such situations. See for instance, U.S. Pat. No. 6,674,642 B1 granted to Richard C. Chu et al. Jan. 6, 2004, disclosing a cooling system in which a heat generatingelectronic component16 is cooled by a low profilecold plate20. Thecold plate20, in turn transfers heat to liquid coolant flowing throughtube24 which is part of aheat exchange assembly30.
• See also U.S. Pat. No. 6,587,343 B2 granted to Shlomo Novotny et al. Jul. 1, 2003, disclosing a cooling system inFIGS. 6-8 in which an electronic component88 is cooled by acold plate64.Cold plate64, which typically includes tubes (not shown) through which liquid flows, is part of a heat exchange system that includes a heat exchanger65 and apump66.
• See also U.S. Pat. No. 6,337,794 B1 granted to Dereje Agonafer et al. Jan. 8, 2002, disclosing inFIGS. 1 and 2, aheat sink10 having multiple channels therethrough within which liquid coolant flows. Theheat sink22 shown inFIGS. 3 and 3A has counterflow channels22aand22bwith inlets24aand24brespectively andoutlets26aand26brespectively. Heat Sink20 includes aninlet plenum30 and anoutlet plenum34 as best shown inFIG. 3A.
SUMMARY OF THE INVENTION
• This invention provides a heat sink or cooler that is very compact and efficient. The cooler is characterized by a plurality of microchannels that are electroformed.
BRIEF DESCRIPTION OF THE DRAWINGS
• FIG. 1 is a side view of a device having an electroformed micro-channel cooler in accordance with the invention;
• FIG. 2 is a section taken substantially along the line2-2 ofFIG. 1 looking in the direction of the arrows and showing a top view of the manifold;
• FIG. 3 is a section taken substantially along the line3-3 ofFIG. 1 looking in the direction of the arrows and showing a top view of a gated part of the two piece electroformed micro-channel cooler shown inFIG. 1;
• FIG. 4 is a section taken substantially along the line4-4 ofFIG. 1 looking in the direction of the arrows and showing a bottom view of a non-gated part of the electroformed micro-channel cooler shown inFIG. 1;
• FIG. 5 is a section taken substantially along the line5-5 ofFIG. 3 in the direction of the arrows and showing details of the two piece electroformed micro-channel cooler shown inFIG. 1;
• FIGS. 6-9 are schematic sections similar toFIG. 5 showing a method of making the electroformed micro-channel cooler shown inFIG. 1;
• FIG. 10 is a schematic section similar toFIG. 5 showing an alternate electroformed micro-channel cooler in accordance with the invention;
• FIG. 11 is a plan view of a tooling plate for assembling electroformed micro-channel coolers of the invention;
• FIG. 12 is a plan view of the tooling plate ofFIG. 11 with a first workpiece mounted on it;
• FIG. 13 is a fragmentary plan view of a second workpiece;
• FIG. 14 is a plan view of the tooling plate and first workpiece ofFIG. 12 with the second workpiece ofFIG. 13 mounted upside down on the first work piece;
• FIG. 15 is a schematic section similar toFIG. 5 showing another alternate micro-channel cooler of the invention; and
• FIG. 16 is a perspective view of yet another alternate micro-channel cooler of the invention.
DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS OF THE INVENTION
• Referring now toFIGS. 1 through 4, adevice10 having an electroformedmicro-channel cooler12 in accordance with the invention is shown.Device10 comprises amanifold14 having aninlet16 communicating with an inlet slot18 and anoutlet20 communicating with anoutlet slot22. Inlet16 feeds a heat transfer medium, such as water into cooler12 via inlet slot18. The coolingmedium exiting cooler12 flows outoutlet20 after being collected byoutlet slot22.
• The electroformedmicro-channel cooler12 is a two-piece structure comprising agated component24 and anon-gated component26.Gated component24 comprises athin sheet28 which serves as a base, a generallyrectangular boundary wall30, and a plurality ofpartition walls32 forming micro-channels34 as best seen inFIGS. 3 and 5. The ends ofpartition walls32 are spaced from the two shorter sides ofboundary wall30 to form aninlet plenum36 at one end and anoutlet plenum38 at an opposite end.Sheet28 has a first series ofgates40 providing passages from inlet slot18 to inletplenum36 and a second series ofgates42 providing passages fromoutlet plenum38 tooutlet slot22.Gates40 and42 are formed by punching holes throughsheet28. While square holes are shown, other shapes may be used.Gated component24 is made of a material that is a good conductor of heat and electricity. Preferably,gated component24 is made of copper which is an excellent conductor of heat and electricity.
• Non-gatedcomponent26 is substantially identical togated component24, the significant exception being that thebase sheet28 does not have the series ofgates40 and42 as best shown inFIG. 4. Non-gatedcomponent26 is placed upside down ongated component24 so that the tops of theboundary walls30 and thepartition walls32 are attached to each other by asuitable layer44 of adhesive, preferably solder as best shown inFIG. 5 which is a substantial enlargement of the section taken along the line5-5 ofFIG. 3 looking in the direction of the arrows. When the gated and non-gatedcomponents24 and26 are attached together, the resulting cooler has a closed chamber with aninlet plenum36 at one end fed throughgates40 inbottom sheet28, anoutlet plenum38 at the opposite end exiting throughgates42 and a plurality of closedmicro channels34 extending from theinlet plenum36 to theoutlet plenum38.
• Referring now toFIGS. 6-9,cooler12 is made as follows. A patterned layer ofphotoresist46 is applied to the top of thethin sheet28 of copper or the like. The photoresist has voids48 exposing thesheet28 where theboundary wall30 andpartition walls32 are desired as best shown inFIG. 6. Theboundary wall30 andpartition walls32 are then electroplated onto thesheet28 in voids48. Voids48 are not filled to the top, leaving room for applying a solder or otheradhesive layer44 to the tops of theboundary wall30 and thepartition walls32 as best shown inFIG. 7. Theadhesive layer44 is then applied after which thephotoresist46 is then stripped as best shown inFIG. 8. Gates40 and42 are punched throughsheet28 before thephotoresist46 is applied or after the photoresist is stripped to provide thegated component24 as best shown inFIGS. 8 and 9. Thenon-gated component26 is made in the same way except thatgates40 and42 are not punched throughsheet28 as best shown inFIG. 9.
• Thenon-gated component26 is then turned upside down and placed on thegated component24 with thelayers44 of solder on the respective tops of the boundary walls and the partition walls engaging each other as shown inFIG. 9, or vice-versa. Thelayers44 of solder are then reflowed to attachcomponents24 and26 together to form themicro-channel cooler12. Using such a technique it is possible to provide a very efficient cooler that is about 1 inch square and 0.012 inch tall with copper sheets about 0.002 inches thick, walls about 0.004 inches thick and the channels about 0.008 inches wide and tall. Such a cooler we found to have a heat transfer coefficient of about 1.5 W/cmcm/degree Centigrade.
• FIG. 10 shows analternate micro-channel cooler112 comprising severalgated components24 and onenon-gated component26 in a stacked arrangement. In this particular arrangement there are six layers with gated component24aserving as the base. Gated component24ais attached to an upside down gated component24bwhich in turn is attached to another upside down gated component24c. Gated component24cis attached to a third upside down gated component24dwhich in turn is attached to another upside down gatedcomponent24e.Gated component24eis attached to an upside downnon-gated component26a. It should be understood that the number of stacked arrangements is virtually unlimited so long as the first layer is a gated component and the last layer is a non-gated component and upside down with respect to the base layer, or vice-versa. With such an arrangement any number of intermediate gated and/or non-gated components can be used, right side up or upside down depending on the flow patterns and manifolding desired.
• The gated andnon-gated components24 and26 can be made singly or in gangs. When thecomponents24 and26 are made in gangs, thecomponents24 and26 can be assembled as explained below.
• Referring now toFIG. 11, atooling plate50 for assembling a gangs of the components of the electroformed multichannel cooler of the invention is shown.Tooling plate50 has aflat surface52 and fouralignment pins54 that protrude upwardly fromflat surface52 in a rectangular array.FIG. 12 is a plan view oftooling plate50 with a first work-piece56 mounted on it. Work-piece56 comprises aflat sheet58 having fouralignment holes59 that receive the respective four alignment pins54.Sheet58 is stamped withseveral slots60 that outline eightbase plates62 of cooler components. Each corner of eachbase plate62 is attached to corners ofother base plates62 and/or to the remainder of thesheet58 by around connector64. Before being assembled totooling50, work-piece56 is processed as described above so that eachbase plate62 is part of a non-gated component such ascomponent26 shown inFIG. 4.
• FIG. 13 is a fragmentary plan view of a second work-piece66. Work-piece66 also comprises aflat sheet68 having fouralignment holes69 for receiving respective fouralignment pins54 oftooling plate50.Sheet68 is also stamped withseveral slots70 that outline eightbase plates72. Each corner of eachbase plate72 is attached to corners ofother base plates72 and/or to the remainder ofsheet68 by around connector74. Work-piece66 is processed as described above so that eachbase plate72 is part of a gated component such ascomponent24 shown inFIG. 2. The second work-piece66 is then mounted upside down on first work-piece56 withalignment pins54 protruding through alignment holes69 as shown inFIG. 14. If two layer electroformed multichannel coolers, such as the cooler12 shown inFIGS. 1-9 are desired, the work-pieces56 and66 stacked on the tooling plate200 are simply heated to reflow the solder so that the two work-pieces are attached to each other to form several two layer coolers. The individual coolers are then separated from each other and the remainder ofsheets58 and68 by removing the attached work-pieces and punching out theround connectors64 and74.
• On the other hand if multi-layer electroformed multichannel coolers, such as the cooler112 shown inFIG. 10, are desired, additional work-pieces, such as work-piece66 are simply stacked upside down on thetooling plate50 until the desired number of layers is reached. The stacked work-pieces are then heated to reflow the solder so that the stacked work-pieces are attached to each other to form several multi-layer coolers. The individual coolers are then separated from each other and the remainder ofsheets58 and68 by removing the attached work-pieces and punching outround connectors64 and74.
• FIG. 15 is a schematic section similar toFIG. 5 showing another alternate arrangement of amicro-channel cooler212 in accordance with the invention.Cooler212 comprises acorrugated skin214 that is electroplated onto a corrugated mandrel (not shown).Skin214 is removed from the mandrel and placed between twoparallel sheets216 and218.Skin214 is attached tosheets216 and218 by sheets reflowing solder layers219 to form a plurality ofparallel micro-channels220 in cooperation withsheet216 and a plurality ofparallel channels222 in cooperation withsheet218.Channels220 and222 alternate.
• Plenums are formed at the opposite longitudinal ends ofchannels220 and222 and eithersheet216 or218 is punched to provide gates opening into the plenums.
• FIG. 16 is a perspective view of yet another alternate arrangement of amicro-channel cooler312.Cooler312 comprises two components—agated component314 and a non-gated component (not shown).Gated component314 comprises athin sheet316 which serves as a base, a generallyrectangular boundary wall318 and a plurality of partition walls320 forming micro-channels322. The micro-channels322 radiate from a central inlet plenum324 to aperipheral outlet plenum326. Inlet plenum324 has agate328 that provides an inlet into plenum324.Outlet plenum326 has a plurality ofgates330 that provide outlets forplenum326.Gates328 and330 are provided by punching holes throughsheet316. While round holes are shown, other shapes may be used.
• Gated component314 is made in the same way asgated component24 by electroplating boundary andpartition walls318 and320 in the voids of a photoresist pattern on the top ofsheet316 and then applying a solder or other adhesive to the tops of the walls. The photoresist is then stripped away.Gates328 and330 are punched throughsheet316 before or after the photoresist is stripped away.
• A non-gated component (not shown) is made in the same way except that gates are not punched throughbase sheet316. The non-gated component is turned upside down and attached togated component314 by reflowing the solder or activating the adhesive to provide themicro-channel cooler312.Cooler312 can be made with just two components as in the case of cooler12 or with several components as in the case of cooler112.
• Many embodiments and adaptations of the present invention other than those described above, as well as many variations, modifications and equivalent arrangements, will be apparent from or reasonably suggested by the present invention and the foregoing description, without departing from the substance or scope of the present invention. Accordingly, while the present invention has been described herein in detail in relation to preferred embodiments, it is to be understood that this disclosure is only illustrative and exemplary of the present invention and is made merely for purposes of providing a full and enabling disclosure of the invention. The foregoing disclosure is not intended or to be construed to limit the present invention or otherwise to exclude any such other embodiments, adaptations, variations, modifications and equivalent arrangements, the present invention being limited only by the following claims and the equivalents thereof.

Claims (24)

1. An electroformed microchannel cooler for liquid cooling comprising:

an upper sheet a lower sheet and a plurality of electroformed partition walls disposed between the upper sheet and the lower sheet to provide a plurality of microchannels for flowing liquid through the cooler.

2. An electroformed microchannel cooler for liquid cooling comprising:

an upper component and a lower component,

each component comprising a sheet and a plurality of electroformed partition walls,

the partition walls of the upper part engaging the partition walls of the lower part to provide a plurality of microchannels for flowing liquid through the cooler in a heat exchange relationship.

3. The electroformed microchannel cooler as defined inclaim 2 wherein the partition walls of each component have ends engaging the ends of the other component.

4. The electroformed microchannel cooler as defined inclaim 3 wherein the ends of the partition walls of one component are soldered to the partition walls of the other component.

5. The electroformed microchannel cooler as defined inclaim 3 wherein each component has a boundary wall outwardly of the plurality of partition walls forming plenums at each end of the cooler and wherein one of the components has gates at each and opening into the plenums.

6. The electroformed microchannel cooler as defined inclaim 5 wherein the components are made of copper.

7. The electroformed microchannel cooler as defined inclaim 6 wherein the sheets have a thickness of about 0.002 inches, the boundary and partition walls have a thickness of about0.004 inches, and the microchannels are about 0.008 inches wide and 0.008 inches tall.

8. (canceled)

9. (canceled)

10. (canceled)

11. (canceled)

12. (canceled)

13. (canceled)

14. (canceled)

15. (canceled)

16. A microchannel cooler for liquid cooling comprising:

an upper component and a lower component,

each component comprising a sheet and a plurality of partition walls,

the partition walls of the upper part engaging the partition walls of the lower part to provide a plurality of microchannels for flowing liquid through the cooler in a heat exchange relationship,

the plurality of partition walls of each component having ends engaging the ends of the plurality of partition walls of the other component.

17. The microchannel cooler as defined inclaim 16 wherein the ends of the partition walls of one component are attached to the ends of the partition walls of the other component.

18. The microchannel cooler as defined inclaim 16 wherein the ends of the partition walls of one component are soldered to the ends of the partition walls of the other component.

19. The microchannel cooler as defined inclaim 16 wherein each component has a boundary wall outwardly of the plurality of partition walls forming plenums at each end of the cooler and wherein one of the components has gates at each end opening into the plenums.

20. The microchannel cooler as defined inclaim 19 wherein the components are made of copper.

21. The microchannel cooler as defined inclaim 19 wherein the sheets have a thickness of about 0.002 inches, the boundary and partition walls have a thickness of about 0.004 inches, and the microchannels are about 0.008 inches wide and 0.008 inches tall.

22. A microchannel cooler for liquid cooling comprising:

an upper component and a lower component,

each component comprising a sheet and a plurality of partition walls,

the partition walls of the upper part engaging the partition walls of the lower part to provide a plurality of microchannels for flowing liquid through the cooler in a heat exchange relationship,

the plurality of partition walls of each component having ends attached to the ends of the plurality of partition walls of the other component,

each component having a boundary wall outwardly of the plurality of partition walls forming plenums at each end of the cooler, and

one of the components having gates at each end opening into the plenums.

23. The microchannel cooler as defined inclaim 22 wherein the components are made of copper.

24. The microchannel cooler as defined inclaim 22 wherein the sheets have a thickness of about 0.002 inches, the boundary and partition walls have a thickness of about 0.004 inches, and the microchannels are about 0.008 inches wide and 0.008 inches tall.

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