Title:
Waterblock for cooling electrical and electronic circuitry
Kind Code:
A1


Abstract:
A waterblock and accompanying cooling tube for carrying away heat generated by electrical or electronic components mounted on a circuit board or other substrate are disclosed. The cooling tube is attached to the waterblock by means of an adhesive or other suitable material, and is not positioned in a groove machined into the surface of the waterblock as has been done in past. The unique design of the waterblock and cooling tube eliminates the need to machine expensive grooves in the waterblock, thereby reducing manufacturing costs.



Inventors:
Andberg, John W. (Santa Cruz, CA, US)
Sugihara, Noriyuki (Campbell, CA, US)
Application Number:
11/257669
Publication Date:
04/26/2007
Filing Date:
10/25/2005
Primary Class:
International Classes:
F28F7/00
View Patent Images:
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Primary Examiner:
ROSATI, BRANDON MICHAEL
Attorney, Agent or Firm:
Gregory W. Osterloth (Denver, CO, US)
Claims:
We claim:

1. A device for cooling at least one heat-generating electrical or electronic circuit in a circuit board, comprising: (a) at least a first waterblock comprising a first surface configured for engagement with or positioning adjacent the circuit board, the waterblock further comprising at least a second surface; (b) at least a first cooling tube comprising at least a first lumen and an outer surface, the at least first lumen being configured to carry a liquid therethrough such that the liquid does not leak from or through the tube to the outer surface thereof; wherein the at least first cooling tube operably engages and is attached to the second surface of the waterblock, the second surface of the waterblock containing no voids, recesses or grooves for accepting the at least first cooling tube therein, the first cooling tube being configured to carry away at least a portion of the heat generated by the electrical or electronic circuit when the liquid flows therethrough.

2. The device of claim 1, wherein the second surface is substantially flat.

3. The device of claim 1, wherein the first surface is configured for attachment to at least a portion of the circuit board.

4. The device of claim 1, wherein a portion of the outer surface of the cooling tube is configured for attachment to the second surface of the waterblock.

5. The device of claim 4, wherein the portion of the outer surface of the cooling tube is substantially flat and configured for engagement or positioning on the second surface of the waterblock.

6. The device of claim 1, wherein the at least first tube is one of circular, elliptical, rectangular, square, D-shaped and flattened in cross-section.

7. The device of claim 1, wherein at least a portion of the cooling tube is serpentine in shape.

8. The device of claim 1, wherein an adhesive-containing material is disposed between the second surface and the cooling tube.

9. The device of claim 8, wherein the adhesive-containing material is at least one of a thermally conductive material, foam, tape, glue, epoxy and thermally conductive epoxy.

10. The device of claim 1, wherein a solder or brazing material is disposed between the second surface and the cooling tube.

11. The device of claim 1, wherein a thermally conductive material is disposed between the second surface and the cooling tube.

12. The device of claim 1, wherein the waterblock is grooveless.

13. The device of claim 1, wherein the waterblock has no groove for accepting the cooling tube therein.

14. The device of claim 1, wherein the first surface is substantially planar.

15. The device of claim 1, wherein the waterblock comprises cooling fins or cooling grooves.

16. The device of claim 1, wherein the waterblock comprises a material selected from the group consisting of aluminum, a ceramic-containing material, stainless steel, copper, zinc, aluminum-silicon carbide, and alloys, combinations or mixtures of all the foregoing.

17. The device of claim 1, wherein the waterblock comprises a material selected from the group consisting of aluminum, stainless steel, copper, zinc, aluminum-silicon carbide and alloys, combinations or mixtures of all the foregoing.

18. The device of claim 1, wherein the first cooling tube comprises a material selected from the group consisting of aluminum, stainless steel, copper, zinc and alloys, combinations or mixtures of all the foregoing.

19. The device of claim 1, wherein the first cooling tube is attached to the waterblock by at least one of glue, epoxy, a thermally conductive adhesive, a fixture for attachment of the tube to the waterblock, at least one bolt, at least one screw, brazing, soldering, welding, crimping and combinations or mixtures of any of the foregoing.

20. The device of claim 9, further comprising a plurality of waterblocks.

21. The device of claim 9, further comprising a plurality of cooling tubes.

22. The device of claim 1, wherein the liquid is selected from the group consisting of water, COOLANOL, Polyalpha Olefin (PAO) dielectric coolant fluid, synthetic hydrocarbon oils ethylene glycol and ethylene glycol/water mixture.

23. A means for cooling at least one heat-generating electrical or electronic circuit in a circuit board, comprising: (a) at least a first means for conducting thermal energy comprising a first surface configured for engagement with or positioning adjacent the circuit board, the thermal energy conducting means further comprising at least a second surface; (b) at least a first means for carrying a fluid within a lumen comprising an outer surface, the lumen being configured to carry the fluid therethrough such that the fluid does not leak from or through the fluid carrying means to the outer surface thereof; wherein the fluid carrying means operably engages and is attached to the second surface of the thermal energy conducting means, the second surface of the thermal energy conducting means containing no voids, recesses or grooves for accepting the fluid carrying means therein, the fluid carrying means being configured to carry away at least a portion of the heat generated by the electrical or electronic circuit when the fluid flows therethrough.

24. The device of claim 22, wherein the second surface is substantially flat.

25. The device of claim 22, wherein the first surface is configured for attachment to at least a portion of the circuit board.

26. The device of claim 1, wherein a portion of the outer surface of the fluid carrying means is configured for attachment to the second surface of the thermal energy conducting means.

27. A method of making a device for cooling at least one heat-generating electrical or electronic circuit in a circuit board, the device comprising at least a first waterblock comprising a first surface configured for engagement with or positioning adjacent the circuit board, the waterblock further comprising at least a second surface, at least a first cooling tube comprising at least a first lumen and an outer surface, the at least first lumen being configured to carry a liquid therethrough such that the liquid does not leak from or through the tube to the outer surface thereof, the at least first cooling tube operably engaging and being attached to the second surface of the waterblock, the second surface of the waterblock containing no voids, recesses or grooves for accepting the at least first cooling tube therein, the first cooling tube being configured to carry away at least a portion of the heat generated by the electrical or electronic circuit when the liquid flows therethrough, the method comprising: (a) providing the waterblock; (b) providing the cooling tube; and (c) attaching the cooling tube to the waterblock.

Description:

FIELD OF THE INVENTION

This invention relates to the field of devices for cooling electrical and electronic circuitry, and more particularly to devices, systems and methods for cooling such circuits using waterblocks and associated tubing.

BACKGROUND

To ensure proper functionality and reliability, manufacturers typically test flash memory chips before shipping them to customers. One system commonly employed to test flash memory chips is the Agilent V5400 Apache Tester.

As illustrated in FIG. 1, one version of the V5400 Apache Tester 100 comprises test head 110, support rack 120 for supplying test head 110 with electrical power, cooling water and compressed air (not shown in the Figures) and computer workstation 130, which serves as the user interface to Tester 100. Manipulator 140 supports and positions test head 110. Support rack 120 is attached to manipulator 140 and serves as the interface between test head 110 and AC power, cooling water and compressed air. Tester 100 may also comprise additional support racks. Agilent's V5400 tester 100 shown in FIG. 1 has the ability to test Flash, DRAM, SRAM and stacked memory devices.

Test head 110 is an important component in the system and comprises tester electronics. In one configuration, tester 100 shown in FIG. 1 offers up to 4,608 channels and 144 independent test sites and is capable of asynchronously testing up to 144 independent devices. Test head electronic components supply power to various devices under test (DUTs) and perform measurements thereon.

As test electronics are forced to ever-greater speeds and densities, a major problem becomes removal of the internal heat generated by test head 110 and the circuitry being tested thereon. In prior generations of tester 100, air cooling was sufficient. As clock speeds have increased, however, signal path length has become a critical issue. Minimizing path length has led to miniaturization by a factor of over thousand in the last five years, to such an extent that it is no longer practical to air-cool current-generation automated test equipment. Greater speed compounds the problem, as heat generation increases with clock speed. Higher pin count testers are becoming the norm as well, further increasing the total thermal power dissipation required in a tester.

The foregoing factors result in liquid cooling being one of the few if not only practical methods for removing heat generated by modern test electronics. The magnitude of the problem becomes fully apparent by noting that high pin count testers having volumes less than 20 ft.3 are now capable of generating between about 40 kW and about 80 kW of heat.

In general the most reliable methods of liquid cooling seek to isolate the cooling fluid from the electronics of tester 100 and test head 110, as opposed to immersion cooling. This is accomplished using waterblocks (sometimes referred to as ‘cold plates’). The active circuitry is mounted to a PC board, which in turn is mounted to a waterblock. In some cases certain components may be directly mounted to the waterblock for enhanced cooling. Various methods of mounting may be used, so the top or the bottom of a PC board may be contacting the waterblock. In many machines, circuits are mounted to both sides of a waterblock, to either minimize space or more fully utilize an expensive component (i.e., a waterblock). The working fluid may be water or some other liquid. Water has the highest cooling performance of the common chosen working fluids, but a variety of considerations may preclude its use in some applications.

Waterblocks are generally constructed of an easily machined metal having high thermal conductivity such as aluminum or copper. Water or another fluid is routed through passages formed in the metal, and thereby removes heat. While this may seem to be a relatively straightforward process, many considerations come into play. For instance, some waterblocks have large internal passages, while others have small cross section passages. Heat transfer considerations generally favor small passages with very high liquid velocities to most effectively remove heat. This aids heat removal, at the expense of greater power required to pump the liquid. It should be noted that the ability to tailor the location of the water passage also can be used to aid the cooling of certain regions or devices that may have higher power dissipation requirements or more stringent temperature requirements.

Most waterblocks are of a style where the working fluid contacts the metal block directly. In one such waterblock, an aluminum plate has long holes drilled through its midplane. Inlet and outlet tubes are glued into two such holes, with the inlet and outlet tubes forming a u-shaped return tube. Other styles of this type of waterblock may also be fabricated by milling corresponding serpentine passages into two plates, gluing the two halves together and adding inlet and outlet tubes in a manner similar to a clamshell.

It has been discovered that waterblocks having inlet and outlet tubes formed therein can spring leaks at any of the glued joints. An alternative might be to braze the inlet and outlet joints, but doing so would introduce the potential for corrosion due to the presence of the brazing alloy.

Another means of providing liquid cooling to a waterblock is to employ a style of waterblock referred to as “tube-in-slab.” To preclude the possibility of leaks occurring at joints, the fluid passage is one continuous piece of tubing. In such a style of waterblock, a serpentine passage is routed into the waterblock. A tube is formed to follow the contour routed in the plate. The whole length of tube is then forced into the plate, resulting in a waterblock with no joints in the fluid path. The cross section of the passage and that of the tube is such that a tight fit exists when the tube is forced into the groove. In some styles, the tube is deformed after insertion to further enhance contact between the tube and block. In addition to the physical contact, a material to aid heat transfer is often placed between the tube and the block. Thermal filled epoxy is often employed in such an application, although the tube may also be brazed in place or even surrounded by a thermal grease. The purpose of the epoxy, glue, brazing material or grease is to enhance heat conduction between the block and the outer surface of the tube, since without their presence a microscopic air gap would otherwise exist.

Although the tube-in-a-slab design has many advantages, barriers to implementing such a construction exist owing to high manufacturing costs. The blocks must be machined to size and shape and then have a suitable groove routed in them. Tubing must be bent to precisely the same shape as the groove. Filler material must be dispensed into the groove, the tubing laboriously forced in, and finally the surface re-cut to remove the filler material that has been squeezed out. For next-generation testers to be economically built, cooling cost on a per unit area basis must decrease considerably.

Some typical prior art waterblocks are illustrated in cross-section in FIGS. 2 and 3. FIG. 2 illustrates a cross section of one type of tube-in-slab waterblock 200, where cross-sectional groove 300 is routed in the relatively thick plate from which waterblock 200 is formed. Groove 300 is sized to accept cooling tube 230 therewithin easily, cooling tube 230 having inner lumen 240, inner surface 2650 and outer surface 250. Thermally conductive epoxy or other suitable material 290 is dispensed in groove 300, cooling tube 230 is inserted in groove 300 and cooling tube 230 is swaged downwardly (and thus outwardly) into groove 300, thereby serving to push outer surface 250 of cooling tube 230 tightly against inner surface 310 of groove 300. Such a tight fit ensures a thin glue line and facilitates heat transfer. Top surface 210 of waterblock 200 is then fly cut for planarity.

FIG. 3 shows another style of waterblock 200 having no bonding material 290 for cooling tube 230, which is swaged into groove 300 (which has a different shape from groove 300 shown in FIG. 2). In FIG. 3, sharp corners in groove 300 and inner surface 310 thereof firmly engage outer surface 250 of cooling tube 230. Such a design permits sufficient deformation of cooling tube 230 tube against inner surface 310 to provide excellent heat transfer. Note that in the design of waterblock 200 shown in FIG. 3, the upper portion of outer surface 250 of cooling tube 230 is positioned below substantially planar first surface 210 of waterblock 200.

Note that the two constructions of waterblock 200 shown in FIGS. 2 and 3 share the disadvantage of being relatively thick, which is necessary to resist the spreading forces applied thereto when cooling tube 230 is placed or forced therein. Waterblock 200 must, of course, be thicker than groove 300 to be milled. Thickness in addition to the groove 310 must therefore be added to waterblock 200 to maintain planarity of waterblock 200 during and after the swaging process.

As will be seen by referring to FIGS. 2 and 3, waterblock 200, groove 300 and cooling tube 230 have rather elaborate and complicated forms and shapes, which those skilled in the art will understand increase considerably the cost of manufacturing and assembling waterblock 200. The elaborate shapes and forms of such waterblocks, grooves and cooling tubes are necessary owing to the significant thermal and mechanical stresses to which waterblock 200 and cooling tube 230 are subjected during use. Moreover, most of the cost of a tube-in-slab waterblock may be ascribed to machining operations for placing the cooling tube in the waterblock and to the subsequent cleanup of adhesive.

It will now be seen that forming the complicated shapes and forms of, and employing the expensive methods and materials used to manufacture, waterblocks 200, grooves 300 and cooling tubes 230 shown in FIGS. 2 and 3 increase manufacturing costs. What is needed is a simpler means of attaching cooling tubes to a waterblock that eliminates the need to machine expensive grooves in the waterblock.

SUMMARY OF THE INVENTION

In accordance with one aspect of the present invention, a device for cooling at least one heat-generating electrical or electronic circuit in a circuit board is provided. In such an embodiment, the device comprises at least a first waterblock comprising a first surface configured for engagement with or positioning adjacent the circuit board, the waterblock comprising at least a second surface, at least a first cooling tube comprising at least a first lumen and an outer surface, the at least first lumen being configured to carry a liquid therethrough such that the liquid does not leak from or through the tube to the outer surface thereof. The at least first cooling tube operably engages and is attached to the second surface of the waterblock, the second surface of the waterblock containing no voids, recesses or grooves for accepting the at least first cooling tube therein, the first cooling tube being configured to carry away at least a portion of the heat generated by the electrical or electronic circuit when the liquid flows therethrough.

In another embodiment of the present invention, a method of making a device for cooling at least one heat-generating electrical or electronic circuit in a circuit board, the device comprising at least a first waterblock comprising a first surface configured for engagement with or positioning adjacent the circuit board, the waterblock further comprising at least a second surface, at least a first cooling tube comprising at least a first lumen and an outer surface, the at least first lumen being configured to carry a liquid therethrough such that the liquid does not leak from or through the tube to the outer surface thereof, the at least first cooling tube operably engaging and being attached to the second surface of the waterblock, the second surface of the waterblock containing no voids, recesses or grooves for accepting the at least first cooling tube therein, the first cooling tube being configured to carry away at least a portion of the heat generated by the electrical or electronic circuit when the liquid flows therethrough, the method comprising providing the waterblock; providing the cooling tube; and attaching the cooling tube to the waterblock.

The present invention further includes within its scope various methods making and using the foregoing components, devices and systems.

The various embodiments of the cooling tube and waterblock of the present invention reduce manufacturing and materials costs, and therefore reduce costs associated with prior art means and methods of cooling electrical or electronic circuitry employing liquid-cooling techniques. For example, many of the various embodiments of the present invention eliminate machining of waterblocks and attendant costs, eliminate time otherwise spent inserting and swaging tubes into grooves, eliminate cleanup after swaging, and use low cost “featureless” cooling tubes attached to one or more sides of one or more waterblocks.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing and other aspects of the invention will become apparent after having read the detailed description of a preferred embodiment of the invention set forth below and after having referred to the following drawings, in which like reference numerals refer to like parts:

FIG. 1 shows a prior art Agilent V5400 Apache memory chip tester;

FIG. 2 shows a schematic cross-sectional representation of a first embodiment of a prior art waterblock and accompanying groove and cooling tube;

FIG. 3 shows a schematic cross-sectional representation of a second embodiment of a prior art waterblock and accompanying groove and cooling tube;

FIG. 4 shows a first embodiment of a waterblock and accompanying cooling tube of the present invention;

FIG. 5 shows a second embodiment of a waterblock and accompanying cooling tube of the present invention;

FIG. 6 shows a third embodiment of a waterblock and accompanying cooling tube of the present invention, and

FIG. 7 shows a fourth embodiment of a waterblock and accompanying cooling tube of the present invention.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS

As employed in the specification and claims hereof, the term “waterblock” means a plate-shaped member formed of a material having thermal characteristics which favor the transfer of thermal energy therethrough; the term “cooling tube” means a member capable of carrying a fluid in at least one lumen thereof, the fluid transporting thermal energy away through the tube from an external source of thermal energy; the term “substantially planar first surface” means a surface of a waterblock to which a cooling tube is attached, the first surface forming a substantially flat surface that may be interrupted by ridges or cooling fins disposed thereon or machined or stamped therein.

Many of the various embodiments of the present invention relate to components, devices, systems and methods of providing waterblocks that reduce manufacturing costs by eliminating machining operations. In such embodiments, a relatively featureless plate or waterblock 200 formed of sheet metal or another suitable thermally conductive material replaces highly machined prior art plates or tube-in-slab waterblocks described above. Although many embodiments of waterblock 200 of the present invention have features such as tapped holes or threaded inserts for mounting a PCB to waterblock 200, such features are very low cost features in comparison to the prior art practice of precision-milling grooves.

Many of the various embodiments of the present invention may further reduce machining costs by permitting waterblock 200 to comprise sheet metal that may be sheared to size at relatively low cost. As shown in FIG. 4, in one embodiment of the present invention, instead of placing cooling tube 230 in routed groove 300, cooling tube 230 one portion of outer surface 250 may be flattened slightly and affixed to sheet metal waterblock 200. In some embodiments of the present invention, cooling tube 230 is flattened to a D- or O-shaped cross section after serpentine bends are formed in cooling tube 230, although other cross-sectional shapes are also contemplated such as circular, elliptical, rectangular and square cross-sections.

Referring now to FIGS. 4 and 5, flattening at least one side of cooling tube 230 increases the surface area over which outer surface 250 of cooling tube 230 engage substantially planar first surface 210 of waterblock 200, thereby promoting adhesion and heat transfer. If the bonding material employed to secure cooling tube 230 to first surface 210 has relatively low thermal conductivity (as is the case with some thermally conductive epoxies), the relatively large surface area of outer surface 250 over which a bond may develop between cooling tube 230 and first surface 210 reduces thermal resistance arising from water flowing through lumen 240 of cooling tube 230. Thermal flux is also promoted by cooling tube 230 having a wide contact area with first surface 210, which reduces the fin effect (the resistance of heat flowing around the tube periphery).

In some embodiments of the present invention, waterblock 200 is formed of sheet metal comprising an aluminum alloy, which has low weight and high thermal conductivity. It is not necessary that cooling tubes 230 be formed of the same alloy or material as waterblock 200. In most applications where use of the present invention is practical and economic, under typical operating conditions no significant thermally-induced stresses will arise from differential expansion of cooling tube 230 and waterblock 200. In some cases it is desired that the sheet metal employed to form waterblock 200 be copper owing to its high thermal conductivity. Note, however, that materials other than aluminum and copper may be used to form waterblock 200, including, but not limited to a ceramic-containing materials, stainless steel, zinc, nickel, thermally-conductive plastic, aluminum-silicon carbide composites, and alloys, combinations or mixtures of all the foregoing, as well as thermally conductive plastics and composites.

Continuing to refer to FIGS. 5 and 6, in many embodiments of the present method thermally conductive epoxy provides the best choice for bonding material 290, although a wide variety of other materials and methods may be used to attach cooling tube 230 to waterblock 200. Among such materials and methods are adhesive-containing materials, suitable thermally conductive materials, foam, caulk, tape, glue, epoxy, soldering and brazing.

Cooling tube 230 may further be secured to waterblock 200 by means of brackets or clips (not shown in the Figures) for holding cooling tube 230 against upper surface 210, either as a means of primary attachment or to provide strain relief. The brackets or clips may have legs or portions that are secured to waterblock 200 by means of bolts, screws or adhesive. In such cases, thermally-filled grease or thermal interface pads may be disposed between outer surface 250 and first surface 210 to facilitate thermal conduction. An electrically nonconductive or electrically insulative, but thermally conductive, material may also be disposed between outer surface 250 and first surface 210 to electrically isolate cooling tube 230 from waterblock 200.

The liquid employed in cooling tube 230 is preferably water, but may also be one or more of COOLANOL (a speciality coiling fluid manufactured by EXXON), polyalpha olefin (PAO) dielectric coolant fluid, synthetic hydrocarbon oil, ethylene glycol, an ethylene glycol/water mixture, or any other suitable cooling fluid.

In preferred embodiments of the present invention, few or no post-attachment steps are required to clean up waterblock 200 after cooling tube 230 has been secured thereto. For example, in preferred embodiments of the present invention no material squeeze-out into critical areas results from attachment of cooling tube 230 to waterblock 200, and thus no cleanup is generally required.

Also in preferred embodiments of the present invention, and unlike in the prior art where high-precision bending of cooling tube 230 was required for tube 230 to fit machined groove 300 in tube-in-slab waterblock 200, relatively featureless and substantially planar first surface 210 of waterblock 200 permits minor imperfections in cooling tube 230 bending or cross section or surface 210 planarity, typically have no impact on proper operation of cooling tube 230 or waterblock 200. The present invention's tube-on-plate construction may also be employed in applications where a single seamless piece of cooling tube 230 eliminates or reduces the possibility of leaks.

In one embodiment of the tube-on-plate method and device of the present invention, a suitable sheet metal plate is sheared from a larger plate to form waterblock 200. Cooling tube 230 is bent into an appropriate serpentine shape, the shape being configured to meet predetermined heat transfer goals. Accordingly, uniform loops may or may not be formed in cooling tube 230, depending on anticipated heat flux and temperature conditions. Cooling tube 230 may further be configured to be routed adjacent critical heat-emitting components. In some applications, cooling tube 230 may also be configured such that tube 230 crosses over itself out-of-plane. Such out-of-plane “jumps” are preferably not left dangling but instead are secured to waterblock 200 by some appropriate means such as brackets, clamps or clips.

In some methods and devices of the present invention, cooling tube 230 is first bent into a preferred serpentine configuration, followed by flattening a portion of outer surface 250 to yield an oval or D-shaped cross-sectional shape by any one of a variety of suitable means. It is preferred that flattening of cooling tube 230 occur after tube 230 has been bent into an appropriate contour so as to minimize the possibility of undesirable out-of-plane flattening of cooling tube 230. Thermal epoxy is then dispensed along flattened portions of cooling tube 230, preferably by a dispensing robot that mixes and accurately dispenses epoxy on such flattened portions. Finally, cooling tube 230 is pressed and held against first surface 210 of waterblock 200 with moderate and uniform force until the epoxy has cured and hardened. Waterblock 200 is then inspected and appropriate holes are drilled to mount one or more PCBs thereon. All of the foregoing steps are carried out with little to no machining or hand work, thereby reducing costs.

In the event cooling tube 230 is attached to first surface 210 of waterblock 200 by means of brazing, a brazing alloy is applied as a paste or plated on flattened portions of tube 230. If cooling tube 230 is secured to waterblock 200 by means of clamps, brackets or clips, a dispensing or screening process may be employed to accurately dispense and spread thermal grease onto appropriate portions of tube 230 or first surface 210. Note that although a sheet metal plate may be employed to form waterblock 200, thicker plates may be employed to form waterblock 200 and indeed may be preferred in some applications.

In addition to lower manufacturing costs, the present invention possesses mechanical advantages. In currently-practiced methods of tube-in-slab construction, some distortion of waterblock 200 results which may range between minor and severe and that that varies with the techniques and materials used. Such distortion presents difficulties with flatness and feature placement, since all major machining has been finished before cooling tube 230 is pressed into routed groove 300. The present invention presents no such difficulties since cooling tube 230 is not pressed or swaged into a groove.

Various embodiments of the present invention are characterized in having relatively slim or low profiles. In such embodiments, waterblock 200 has a relatively small thickness 270, 270a or 270b, which in turn permits the total thickness 280 of waterblock/PCB assembly 295 to be relatively small. See FIGS. 5, 6 and 7.

As illustrated in FIGS. 6 and 7, circuit board 320 may require cooling but does not afford sufficient space and volume to permit the use of a large waterblock. Accordingly, in alternative embodiments of the present invention, typically although not necessarily where circuit board 320 is characterized in having relatively low heat dissipation, cooling tube 230 is routed around the periphery of board 320. See FIGS. 6 and 7. In another alternative embodiment of the present invention, a sheet metal plate or other suitable material having a recess disposed in a portion thereof for accepting circuit board 320 therein and forming a periphery thereabout is employed to form waterblock 200, more about which we say below.

The material from which waterblock 200 of FIG. 6 is preferably formed is copper owing to its low thermal resistance, but other suitable metals, alloys and materials may be used. Cooling tube 230 is mounted along the periphery of circuit board 320 and preferably on the same side of the PCB as electrical/electronic circuitry mounted thereon to permit double use of space above the plane of the board bottom (see FIG. 6). Note that some areas of sheet metal in waterblock 200 of FIG. 6 could be punched out relatively easily to permit back side components to be mounted thereon.

Yet another means of providing a space- and volume-saving construction in the present invention is illustrated in FIG. 6, where circuit board 320 has electrical/electronic circuitry and components 330 mounted on both sides thereof. In such an embodiment of the present invention, surfaces 220a and 220b may be configured to engage the surfaces of components 330 mounted on circuit board 320, such components being optimized for top-side cooling (as is usually the case for components designed for air cooling). Cooling tube 230 is preferably although not necessarily located at the periphery of circuit board 320 and is bonded to waterblocks 200a and 200b by means of adhesives 290a and 290b. Waterblocks 200a and 200b dissipate heat generated by components 330 on both sides of circuit board 320.

Small gaps between components 330 and waterblocks 200a and 200b arising from non-planarity of components or waterblocks may be filled by a thermal interface material disposed in such gaps to enhance thermal conductivity. In another embodiment of the present invention, mechanical pressure generated by appropriately positioned bolts, screws, glue or other means of fastening cause surfaces 220a and 220b to engage the bottom and top surfaces, respectively, of components 330 to enhance thermal conductivity. Cooling tube 230 may encircle circuit board 320 or be positioned on one, two or three sides thereof, depending on heat flux and size requirements.

The present invention includes within its scope various methods of making and using waterblock 200 and cooling tube 230 of the present invention.

As will now become apparent, while specific embodiments of waterblock 200 and cooling tube 230 of are described and disclosed herein, many variations and alternative embodiments of the present invention may be constructed or implemented without departing from the spirit and scope of the present invention. It is to be understood, therefore, that the scope of the present invention is not to be limited to the specific embodiments disclosed herein, but is to be determined by looking to the appended claims and their equivalents. Consequently, changes and modifications may be made to the particular embodiments of the present invention disclosed herein without departing from the spirit and scope of the present invention as defined in the appended claims.