Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
2003-02-07
2004-05-25
Chervinsky, Boris (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S698000, C361S699000, C257S714000, C174S015100, C174S015200, C165S080400, C165S104260
Reexamination Certificate
active
06741469
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention is directed to the field of microelectronics, and more particularly, to heat dissipation in microelectronics.
2. Description of Related Art
Currently, demand for higher performing microprocessing devices is resulting in microelectronic components having increasing levels of power density and heat dissipation. As the reliability and lifespan of a microelectronic component is dependent on the operating temperature, removal of heat from microelectronic components has become one of the most important issues facing computer systems designers today.
Conventional thermal control schemes, such as heat sinks, air cooling with fans, thermoelectric cooling, heat pipes, and vapor chambers have either reached their practical application limit or are soon to become impractical for recently emerged microelectronic components. Current heat dissipation of values of 20 W to 50 W are estimated to increase to 100 W and even 200 W in the next five to ten years. Thus, the reliability of these microelectronic component systems will suffer if high temperatures are permitted to exist.
In an attempt to address the need for greater heat dissipation, one prior art technique utilized a microelectromechanical system (MEMS)-based-micro-channel cooling system embedded in the substrate of the microelectronic component as further described herein with reference to FIG.
1
.
FIG. 1
illustrates a functional diagram of an integrated circuit (IC) chip package
100
including a voltage-controlled, electrokinetic (EK) microcooler system
110
embedded in a substrate
114
on which an IC
112
is formed. EK microcooler system
110
removed dissipated heat from integrated circuit (IC)
112
utilizing a two-phase cooling loop having an electrokinetic (EK) pump
116
.
In this prior art technique, liquid was circulated under high pressure (for example, 5 atm) in a closed loop at least part of which was in thermal contact with underlying IC
112
. Heat exchangers, such as microchannels or microjets, transferred heat from IC
112
to an evaporator region
120
of the closed loop above IC
112
by thermally conductive contact with evaporator region
120
. An example of a microchannel heat exchanger is described in U.S. Pat. No. 4,573,067 to Tuckerman et al. entitled “Method and Means for Improved Heat Removal in Compact Semiconductor Integrated Circuits” and hereby incorporated by reference in its entirety.
The circulated liquid absorbed the heat and evaporated in evaporator region
120
. The vapor then traveled through the closed loop to a condenser region
118
of the closed loop that was lower in temperature than evaporator region
120
. The vapor then condensed to liquid releasing the heat. The liquid was then pumped back to evaporator region
120
by EK pump
116
and the cooling cycle repeated.
Advantageously, EK microcooler system
110
had no solid moving parts and was implemented as part of the fabrication process of substrate
114
of IC
112
, and was therefore expected to be more compact and reliable. The high liquid pressure enabled two-phase micro heat exchangers for greater heat dissipation, utilized very small amounts of voltage to control EK pump
116
and, therefore, had reduced power consumption.
Unfortunately, MEMS-based micro-channel heat exchanger systems that were embedded in the substrate of a central processor unit (CPU) or an application specific integrate circuit (ASIC) using the fabrication process for cooling of microelectronic components had thermal inertia, heat removal inefficiency and very large heat rejection to heat absorption areas. Consequently, these systems provided little more heat dissipation than earlier, less costly heat dissipation techniques preventing their widespread application in the electronic industry.
SUMMARY OF THE INVENTION
According to the invention, a refrigeration cooling assisted MEMS-based micro-channel cooling system removes high heat densities by direct spot-cooling of electronic components using a primary cooling system thermally coupled with a secondary chip embedded cooling system. The invention maintains low levels of energy consumption with acceptable component sizes. The invention provides highly efficient chip embedded cooling with continuous or intermittent operation of the primary cooling system.
In one embodiment, the refrigeration cooling assisted MEMS-based micro-channel cooling system includes: a primary cooling system, such as a multiple compressor refrigeration heat sink module; at least one integrated circuit (IC) chip embedded secondary cooling system, such as a MEMS-based micro-channel cooling system; and at least one socket thermally coupling the primary and secondary cooling systems.
In one embodiment, a portion of an evaporator line from the primary cooling system is extended to the socket and is positioned in thermally conductive contact with the socket. When the IC chip embedded secondary cooling system is positioned in thermally conductive contact with the socket, heat generated by the integrated circuit is initially removed by the IC chip embedded secondary cooling system, and dissipated into the socket. The heat is then transferred from the socket to the evaporator line. The evaporator line, e.g., refrigerant circulating within the evaporator line, transfers the dissipated heat away from the socket to the primary cooling system for further dissipation.
By continually, or intermittently, removing heat transferred from the IC chip embedded secondary cooling system through the socket to the primary cooling system, the thermal inertia and heat rejection areas experienced in the prior art MEMS-based micro-channel cooling systems are significantly reduced allowing for higher heat dissipation levels.
It is to be understood that both the foregoing general description and following detailed description are intended only to exemplify and explain the invention as claimed.
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Goodson, K. “Herectic Current Projects Current Projects Index Electrokinetic Micro Coolers”, pp. 1-2 [online]. Retrieved on Jun. 13, 2003. Retrieved from the Internet: <URL:http://www.darpa.mil/mto/heretic/projects/7.html>.
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Chervinsky Boris
Gunnison McKay & Hodgson, L.L.P.
Norris Lisa A.
Sun Microsystems Inc.
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