Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2000-02-11
2001-10-09
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S699000, C361S700000, C361S711000, C165S170000, C165S165000, C062S259200, C257S714000
Reexamination Certificate
active
06301109
ABSTRACT:
TECHNICAL FIELD
The present invention is generally related to providing cooling systems for electronic devices requiring cooling. More particularly, the present invention is directed to an isothermal heat sink for uniformly cooling an electronics module.
BACKGROUND OF THE INVENTION
In recent years, the semiconductor industry has taken advantage of the fact that CMOS circuits dissipate less power than bipolar circuits. This has permitted more dense packaging and correspondingly, faster CMOS circuits. However, almost no matter how fast one wishes to run a given electronic circuit chip, there is always the possibility of running it faster if the chip is cooled to lower temperatures during operation. This is particularly true of computer processor chips and even more true of these chips when they are disposed within multichip modules (MCMs), which generate significant amounts of heat. Because there is great demand to run processor modules at higher speeds, the corresponding clock frequencies at which these devices must operate become higher. In this regard, it should be noted that it is known that power generation rises in direct proportion to the clock frequency. Accordingly, the desire for faster computers generates not only demand for computer systems but generates thermal demand in terms of energy which must be removed for faster, safer and more reliable circuit operation. In this regard, it is to be particularly noted that, in the long run, thermal energy is the single biggest impediment to semiconductor operation integrity.
Multichannel heat sinks have been developed for extraction of heat generated by, for example, integrated electronic circuits, multi-chip modules, diode laser arrays, or other electro-optic devices under conditions of high heat flux density. Coolant flow in the channels is conventionally unidirectional, i.e., the coolant enters the heat sink through an inlet at one end and flows through parallel channels to an outlet at the other end.
An enhanced heat sink is described in U.S. Pat. No. 5,099,910, entitled “Microchannel Heat Sink With Alternating Flow Directions,” the entirety of which is hereby incorporated herein by reference. Briefly summarized, this patent presents a heat sink wherein temperature rise along multiple parallel channels is addressed by providing alternating coolant flow directions through the channels of the heat sink. Although improving heat surface temperature distribution over the uniform flow direction approach, further enhancements are believed desirable to more closely achieve the goal of a truly isothermal heat sink for an electronic device.
DISCLOSURE OF THE INVENTION
Briefly described, the present invention comprises an apparatus for cooling an electronic device which includes a heat sink member with a surface for making thermal contact with the electronic device. The heat sink member has a plurality of channels for carrying coolant fluid. The plurality of channels comprise a first group of channels and a second group of channels, wherein the first group of channels and the second group of channels are positioned generally alternately across the member so that coolant fluid alternates direction across the member. At least one cross-flow opening is also provided between at least two adjacent channels of the plurality of channels such that coolant fluid can flow within the member between at least some channels of the first group of channels and the second group of channels.
To restate, provided herein are various embodiments for attaining an isothermal heat sink for use in a cooling system of an electronic device. Enhanced performance of the cooling system is attained by more uniformly dissipating heat across the thermal interface surface of the heat sink, thereby more uniformly cooling the electronic device to which the heat sink is coupled. By more uniformly dissipating heat across the thermal interface surface, thermal resistance between the heat sink and electronic device is lowered. Further, since timing (synchronization) and noise tolerances are a function of electronic device temperature, maintaining circuits as isothermal as possible minimizes the temperature effect resulting in improved noise margin and clock skew. This effect is more pronounced in multichip modules.
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Chu Richard C.
Ellsworth, Jr. Michael J.
Simons Robert E.
Datskovsky Michael
Esq. Lily Neff
Heslin & Rothenberg, P.C.
International Business Machines - Corporation
Picard Leo P.
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