Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-12-07
2002-06-25
Thompson, Gregory (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C174S016300, C165S080200, C165S185000, C257S707000, C257S713000, C257S722000, C361S710000, C361S715000
Reexamination Certificate
active
06411513
ABSTRACT:
CROSS-REFERENCE TO RELATED APPLICATIONS
Not Applicable
FEDERALLY SPONSORED RESEARCH OR DEVELOPMENT
Not Applicable
BACKGROUND OF THE INVENTION
The invention relates in general to conduction cooling of surfaces and in particular to conduction cooling of heat generating components, such as high power semiconductors and integrated circuits (IC's), where variations in gap distance and/or angular misalignment (tilt) between its surface and a cooling surface must also be accommodated. The invention may produce embodiments to interface between surfaces with various shapes, including, but not limited to: flat, two-dimensionally curved, three-dimensionally curved, cylindrical and tubular surfaces. The invention also relates to simple methods of making the devices.
Continuing demands in electronic technology of greater integration, faster operating speeds, greater output power, and reduced package size have increased the density of heat generation and magnified cooling requirements. Further, electronic components are often sealed in modules to protect them from liquid cooling systems or harsh environments. Manufacturing tolerances and thermal expansion properties of the various items along the thermal path, however, can combine to create conflicting thermal effects. Ignoring these effects can result in large mechanical stresses, inconsistent thermal contact, erratic functioning of the component, and premature component failure. A compliant, thermally conductive interface device is often needed between a heat generating component and a module cover plate or heat sink to accommodate manufacturing tolerances and thermal effects, reduce mechanical stresses, and provide consistent cooling performance. In addition, similar interface devices are often needed with components having curved or cylindrical surfaces, such as traveling wave tubes and heat pipes. Many designs have been developed to address these needs. A few of the more relevant designs are briefly described below.
U.S. Pat. No. 4,485,429, describes a plurality of thin wires anchored to a cover plate that press down onto a heat generating component causing the individual wires to bow in a springlike action to accommodate component height and tilt. Although each thin wire has high thermal resistance, filling the space above the component with a plurality of wires reduces the overall thermal resistance to a low level. Bowing of the wires, however, must be limited (approximately 0.13 mm compression) to retain elastic springback capability and prevent excessive spreading of the wire bundle in a fan-like (or broom-like) manner. Excessive fan-like spreading can reduce thermal contact efficiency between the ends of the wires and the component surface, and reduce wire density over the component. U.S. Pat. No. 4,156,458 describes a similar system using foils instead of wires. Straight foils are stacked against each other (without gaps) and bonded to a cover plate at an acute angle (45). Soldering the foils to a component surface (after fan-like spreading of the foil bundle) is also described to complement thermal contact. Soldering, however, stiffens the foils, increases resistance to further compression, and can impose lateral forces on the component due to the angular alignment of the foil bundle.
U.S. Pat. No. 4,993,482 describes the use of highly conductive springs laid on their sides. Every loop of the springs represents two wires thermally linking the component to the cover plate. Thermal performance is dependent on good thermal contact with the springs and the ability to fill the void between the component and the cover plate with thermal links. U.S. Pat. No. 4,156,458 also describes a similar system using a tubular roll of foil instead of a spring.
IBM Technical Disclosure Bulletin article entitled “LSI Cooling and Packaging Design” dated February, 1994, pages 99-100, and U.S. Pat. No. 5,528,456 describe other designs using corrugated sheets of highly conductive materials to interface between the component and the cover plate. The corrugations deform to accommodate height and tilt variations.
U.S. Pat. Nos. 5,557,501 and 5,650,914 describe a system where a plurality of foil cantilevers are fabricated on thermally conductive plates using conventional photolithography and etching techniques. The cantilevers are bonded between the plates to produce a plurality of short thermal links similar to the corrugations described previously. Half of the cantilevers are made in opposite lateral directions to substantially neutralize lateral forces on the component. Multi-layered cantilevers are also described. Their ability to fill the void between the component and the cover plate, however, remains lower than U.S. Pat. Nos. 4,485,429 and 4,156,458 described previously.
Similar interface devices for use between curved or cylindrical surfaces, such as traveling wave tubes and heat pipes, are described in U.S. Pat. Nos. 3,746,087 and 3,823,772. Cone-shaped structures, anchored circumferentially to the inside surface of a cylindrical cavity, are metallurgically bonded to a coaxially aligned cylindrical component producing a permanent installation. A design is also described that uses thin fins bonded tangentially to a cylindrical component. U.S. Pat. No. 4,358,707 describes a plurality of angled cantilevers machined into the outer surface of a cylindrical heat generating component.
Despite the wide variety of existing designs, a need continues for improved interface devices that provide high conduction cooling capabilities between two generally flat surfaces while accommodating a range of gap distances and angular misalignment (tilt) between the surfaces. A need also exists for similar devices to interface between curved or variously-shaped surfaces to provide similar benefits.
The present invention sets out to address these needs.
BRIEF SUMMARY OF THE INVENTION
According to one aspect of the invention there is provided an interface device, comprising:
at least one foil assembly, with each foil assembly comprised of a plurality of flexible foils, the foils extending between a first surface and a second surface and in a length direction along the surfaces, with each foil comprised of a proximal edge near the first surface, a flexing section, and a distal edge near the second surface, the foils within the foil assembly are stacked in a densely-packed, nested fashion with the proximal edges of adjacent foils distributed with a proximal edge spacing factor and the distal edges of adjacent foils distributed with a distal edge spacing factor so that interstitial separation distances are provided between the flexing sections of adjacent foils to accommodate flexing and compression of the distance between the first and second surfaces to a desired minimum for the foil assembly.
This invention also considers the interface device as defined above wherein the interstitial separation distances are generally depleted and the flexing sections of adjacent foils are generally against each other when the distance between the first and second surfaces is at the desired minimum for the foil assembly. This invention also considers the interface device as defined above wherein the relative spacing between adjacent proximal edges and the relative spacing between adjacent distal edges remains generally fixed during device operation. This invention also considers the interface device as defined above wherein the proximal edges of the foils are fixed by bonding the proximal edges of adjacent foils together, and/or by bonding the proximal edges to a common bonding surface such as a first member. The first member may be, for example, a heat generating component, a heat sink, a cover plate, or a collector plate. The bonded plurality of adjacent proximal edges, and/or the first member (with its bonds to the proximal edges of the foils) may also be flexible and deformable in a direction perpendicular to the foil length direction. This provides a capacity for the first surface of the foil assembly to bend and conform to a range of curved surfaces. This invention also considers
LandOfFree
Compliant thermal interface devices and method of making the... does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Compliant thermal interface devices and method of making the..., we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Compliant thermal interface devices and method of making the... will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2962249