U.S. patent application number 14/672196 was filed with the patent office on 2016-09-29 for cost-effective cooling method for computer system.
The applicant listed for this patent is Banqiu Wu, Ming Xu. Invention is credited to Banqiu Wu, Ming Xu.
Application Number | 20160286690 14/672196 |
Document ID | / |
Family ID | 56878418 |
Filed Date | 2016-09-29 |
United States Patent
Application |
20160286690 |
Kind Code |
A1 |
Wu; Banqiu ; et al. |
September 29, 2016 |
Cost-effective cooling method for computer system
Abstract
A computer system using regular IC or 3D IC is cooled by using
liquid coolants such as water, oil, and ionic liquid. Liquid
coolant flows in a closed coolant conduit which is configured to
thermally contact heat-generating components in a computer system
and a large water body such as river and reservoir. The heat
created in computer system is carried out by liquid coolant and
dissipated to large water body. The cooling system is simple and
cost-effective.
Inventors: |
Wu; Banqiu; (San Jose,
CA) ; Xu; Ming; (San Jose, CA) |
|
Applicant: |
Name |
City |
State |
Country |
Type |
Wu; Banqiu
Xu; Ming |
San Jose
San Jose |
CA
CA |
US
US |
|
|
Family ID: |
56878418 |
Appl. No.: |
14/672196 |
Filed: |
March 29, 2015 |
Current U.S.
Class: |
1/1 |
Current CPC
Class: |
H05K 7/20772 20130101;
H05K 7/2079 20130101 |
International
Class: |
H05K 7/20 20060101
H05K007/20 |
Claims
1. A cooling system for a plural of heat-generating components in a
computer system, comprising a. One or plural of heat-exchanging
channels configured to be placed in thermal contact with said
heat-generating components; b. A liquid-liquid heat exchanger
including an exchanger conduit and an external surface wherein a
liquid coolant flows in said exchanger conduit; said external
surface thermally contacts a large water body; heat is dissipated
from said liquid coolant in said exchanger conduit to said large
water body; c. A closed conduit including a supply conduit, said
heat-exchanging channels, a return conduit, and said exchanger
conduit of said liquid-liquid heat exchanger; wherein said liquid
coolant is configured to be circulated in said closed conduit; said
supply conduit is configured to flow said liquid coolant into said
heat-exchanging channels; a return conduit is configured to flow
said liquid coolant out of said heat-exchanging channels; said
supply conduit and said return conduit have larger cross-sectional
areas for flowing of said liquid coolant than sum of
cross-sectional areas of said heat-exchanging channels; d. A pump
configured to drive circulating of said liquid coolant in said
closed conduit; e. A means for controlling flow rate of said liquid
coolant in said closed conduit; f. A means for preventing said
external surface of said liquid-liquid heat exchanger from
contamination by said large water body;
2. The cooling system of claim 1, wherein said liquid coolant is
deionized water or ionic liquid or oil.
3. The cooling system of claim 1, wherein said pump is an
electromagnetic pump or a magnetic pump.
4. The cooling system of claim 1, wherein said means for
controlling flow rate of said liquid coolant in said closed conduit
includes a pump and valves;
5. The cooling system of claim 1, wherein said means for preventing
said external surface of said liquid-liquid heat exchanger from
contamination by said large water body is a grate.
6. A cooling system for a plural of integrated circuits in a
computer system, comprising a. A first integrate circuit having
first bonding side and first non-bonding side; b. A second
integrated circuit having second bonding side and second
non-bonding side, wherein said first bonding side of said first
integrated circuit is bonded with said second bonding side of said
second integrated circuit using through silicon via interconnect
for mechanical bonding and electric interconnection between said
first integrated circuit and said second integrated circuit; c. One
or plural of first heat-exchanging channels configured to be placed
in thermal contact with said first non-bonding side of said first
integrated circuit; d. One or plural of second heat-exchanging
channels configured to be placed in thermal contact with said
second non-bonding side of said second integrated circuit; e. A
liquid-liquid heat exchanger including an exchanger conduit and an
external surface wherein a liquid coolant flows in said exchanger
conduit; said external surface thermally contacts a large water
body; heat is dissipated from said liquid coolant in said exchanger
conduit to said large water body; f. A closed conduit including a
supply conduit, said first heat-exchanging channels, said second
heat-exchanging channels, a return conduit, and said exchanger
conduit of said liquid-liquid heat exchanger; wherein said liquid
coolant is configured to be circulated in said closed conduit; said
supply conduit is configured to flow said liquid coolant into said
first heat-exchanging channels and said second heat-exchanging
channels; a return conduit is configured to flow said liquid
coolant out of said first heat-exchanging channels and said second
heat-exchanging channels; said supply conduit and said return
conduit have larger cross-sectional areas for flowing of said
liquid coolant than sum of cross-sectional areas of said first
heat-exchanging channels and second heat-exchanging channels; g. A
pump configured to drive circulating of said liquid coolant in said
closed conduit; h. A means for controlling flow rate of said liquid
coolant in said closed conduit; i. A means for preventing said
external surface of said liquid-liquid heat exchanger from
contamination by said large water body;
7. The cooling system of claim 6, wherein said liquid coolant is
deionized water or ionic liquid or oil.
8. The cooling system of claim 6, wherein said pump is an
electromagnetic pump or a magnetic pump.
9. The cooling system of claim 6, wherein said first integrated
circuit is a microprocessor unit and said second integrated circuit
is a dynamic random access memory.
10. The cooling system of claim 6, wherein said second integrated
circuit is a non-volatile memory chip.
11. The cooling system of claim 6, wherein said large water body is
a river or a reservoir or an ocean.
12. The cooling system of claim 6, wherein said computer system is
a server.
13. A cooling method for a plural of integrated circuits in a
computer system, comprising a. Providing a first integrated circuit
and a second integrated circuit; b. Providing a first component
liquid conduit configured for a liquid coolant having thermal
contact with said first integrated circuit; c. Providing a second
component liquid conduit configured for said liquid coolant having
thermal contact with said second integrated circuit; d. Providing a
liquid-liquid heat exchanger having a heat-exchanging conduit and
an external surface configured to thermally contact the a water in
a large water body; wherein said liquid coolant dissipates heat to
said water in said large water body; e. Circulating said liquid
coolant in said first component liquid conduit, said second
component liquid conduit, and said heat-exchanging conduit for
carrying out heat from said first integrated circuit and said
second integrated circuit, and dissipating heat to said large water
body; f. Providing a means for said liquid coolant having a
controllable flow rate on said first component liquid conduit and
said second component liquid conduit; g. Dissipating heat from said
liquid coolant in said heat-exchanging conduit to said water
flowing in said large water body; h. Providing a means adjusting
flow rates in said first component liquid conduit and in said
second component liquid conduit;
14. The cooling system of claim 13, wherein said large water body
is a river, or a reservoir, or an ocean.
15. The cooling system of claim 13, where said liquid coolant is a
deionized water, or oil, or ionic liquid.
16. The cooling system of claim 13, wherein said computer system is
a server.
17. The cooling system of claim 13, wherein said first integrated
circuit is a microprocessor unit.
18. The cooling system of claim 13, wherein said second integrated
circuit is a dynamic random access memory.
19. The cooling system of claim 13, wherein said second integrated
circuit is a non-volatile memory chip.
20. The cooling system of claim 13, wherein said means adjusting
flow rates in said first component liquid conduit and in said
second component liquid conduit include one or plural of
electromagnetic pump and one or plural of valves.
Description
FIELD
[0001] The embodiment of present invention is generally related to
liquid cooling system for heat-generating components of computers.
More specifically, the present invention relates a cost-effective
liquid cooling system in computer systems for regular integrated
circuit and stacked three-dimensional (3D) integrated circuit (IC)
used in data center.
BACKGROUND
[0002] Since it was invented in 1958, IC has been scaled to improve
the performance. However, after the turn of the century, scaling
resulted in short-channel effect and memory wall, which requires
other approach to improve the IC performance more effectively.
[0003] 3D IC offers a reasonable route to further improve IC
performance. It improves IC performance by increasing device
density, reducing the interconnect delay, and breaking memory wall
with the application of 3D stacking using through silicon via
(TSV). 3D IC also makes one chip package have more functional
diversification than those enhanced only by shrinking the size of
the features.
[0004] The main advantages of 3D IC are the smaller form factor,
low energy consumption, high speed, and functional diversification.
The biggest challenge in 3D IC stacking technology using TSV is
thermal management owing to the high heat flux up to about 200
watts per square centimeter.
[0005] Data centers for internet and mobile devices are the most
critical components in our information age. They serve industries,
civil communications, military and defense applications, and
transportations. Data centers consist of multiple computers usually
called servers and switches. Both of them use many ICs. When a
computer works, ICs will change status, or change the on-and-off
status, which consumes electricity and generates significant heat.
Even when computer system is at idle condition, it still consumes
electricity due to the current leakage and circuit requirement.
[0006] It is predicted that 3D ICs will be an enabler for
improvement of data center performance and efficiency with positive
consequences for global energy consumption and environment.
Disclosure of this invention will provide a cost-effective solution
of 3D IC thermal management.
[0007] Multiple servers are accommodated in a server rack at data
center. Each computer consumes significant electricity. It is
common for a server (computer) to consume over a hundred watts. In
a server rack, i.e. a module of servers, there are multiple
computers. Similarly, there are many server racks in a data center.
Therefore, a data center consumes large amount of electricity and a
large data center consumes the same amount of electricity as a
small or medium size town. Among the energy used in data centers,
most electricity is consumed by servers and their cooling systems.
It is quite often that cooling system uses the same amount of
electricity as the server computers. It is estimated that the date
centers consume about two percent of total electricity generated
worldwide.
[0008] Power usage effectiveness (PUE) is usually used to measure
the efficiency of a data center. It is defined as a ratio of total
energy used by facility to that used by information technology (IT)
equipment. An ideal PUE is 1.0, but average PUE worldwide now is
about 2.0 although some data center claims their PUE is
significantly below 2.0. The average PUE value of 2.0 indicates the
necessity to improve the data center cooling effectiveness. One
approach to improve the cooling efficiency is to use water cooling
to replace current air cooling. In the past, water cooling was used
for large scale computers, but did not obtain large scale
application for personal computers or servers in data center
because of its limitation by the shape of heat-generating
components and thus the complexity.
[0009] As the dimensions of integrated circuit components decrease,
more components are compacted in a given area of a semiconductor
integrated circuit. Accordingly, more transistors are held on a
given area and thus more heat is generated in the same area. In
order to keep the IC temperature in allowed range for proper
performance, heat generated has to be transferred out of integrated
circuit effectively and economically. With the internet devices
getting popular, more and more servers are installed and in service
to support the internet function. The trend of applications of more
mobile devices and cloud technology will drive more electricity
consumption at data centers in the future.
[0010] Current servers are located in an air-conditioned
environment, usually in a specially designed building. The heat
generated by microprocessors, memory chips, and power supply chips
is released locally, which is like a large heater in a room cooled
by air conditioner. Due to the low efficiency of air conditioner,
the cooling system uses lots of electricity, occupies large
footprints, and causes high costs.
[0011] Accordingly, it is very significant to provide an effective
method to reduce cooling power and improve cooling efficiency for
computer system, especially for the system with large number of
computers such as data center. Cooling technology now becomes an
enabler to improve data center efficiency.
[0012] Improving cooling system in data center not only saves
energy consumption, but also benefits ecological and environmental
systems. Reduction of electricity consumption in data center
cooling system will significantly decrease the emission of carbon
dioxide amount, which equivalents to shut down multiple coal power
plants with environmental benefit in addition to the cost
reduction.
[0013] The heat generated in electronic devices in a data center
has to be transferred outside the accommodating construction and
dissipated to environment. In order to prevent the overheat of ICs,
the surface of the ICs should be kept not very high, which means
the temperature difference between high temperature source (IC
surface) and low temperature environment is very low, resulting in
the challenge in engineering realization and high costs in cooling
system.
[0014] Traditionally, heat-generating components in computers are
cooled by cold air supplied by air-conditioners. The air exchanges
heat with heat generating components and dissipates it on chiller's
cold surface. Lots of chillers and fans have to be used and thus
cooling process consumes significant electricity and results in
high costs. Lots of power is used by fans in the server rack to
dissipate heat from component surface to air by blowing air through
the server rack, consuming energy and making noise.
[0015] In order to lower the cost of using air conditioner, cold
air is used to directly cool the heat generating components in
winter at north areas. However, the air humanity has to be
controlled well and the application is also limited by weather and
season.
[0016] Now, cooling water is becoming popular for cooling the
heat-generating components for computers. Current heat-generating
components are mainly microprocessor unit (MPU), dynamic
random-access memory (DRAM), and power chips. MPU has a flat shape
and it is relatively easy to use liquid cooling on a flat surface.
However, it is difficult to use liquid cooling on DRAM dual in-line
memory module (DIMM) due to the irregular shape although some
attempts were tried.
[0017] In order to overcome the intrinsic problem mentioned above,
liquid cooling was used by circulating liquid coolant on the
surface of ICs to improve the efficiency. However, this method has
to use chillers to cool the liquid, resulting in a low cooling
efficiency.
[0018] Therefore, natural water body was used for data center
cooling. Air cooling of server rack was combined with heat
dissipation to large natural water bodies such as ocean, river, and
lake. However, there are lots of challenges for the realization of
this method. In this invention, a cost-effective method is
disclosed for improving server cooling and data center
efficiency.
SUMMARY
[0019] Methods for cost-effective regular ICs or 3D ICs in a
computer system are provided herein. In an embodiment, a cooling
method includes: (a) circulating a liquid coolant to dissipate heat
from regular of 3D IC heat-generating components such as MPU,
memory chips, and power chips to the liquid coolant; (b)
heat-dissipating from the liquid coolant directly to a large water
body such as river, reservoir, and ocean.
[0020] In one embodiment, there are a coolant supply conduit and a
coolant return conduit connecting liquid conduit on heat-generating
components of regular ICs or on both sides of the IC package for 3D
IC, the former supplies the coolant to heat-generating components
in servers, and the latter carries the heated coolant out of
heat-generating components for dissipating heat directly to a river
or other large water body while the coolant is reused by
circulation in a closed loop.
[0021] The most important thing for a reliable cooling performance
is to keep the flow rate controllable in the cooling conduit on the
heat-generating components. This is enabled by controlling the
pressure in the supply conduit by using pumps and valves, large
ratio of cross-sectional area of supply conduit to the sum of
cooling conduit cross-sectional areas on the heat-generating
components. The large cross-sectional area of supply conduit
determines the constant pressure of liquid coolant and then the
controllable flow rates in cooling conduit on each heat-generating
component with reliable cooling performance.
[0022] It is very important that the coolant is all weatherproof
liquid and pump maintenance is easy and reliable. In one embodiment
of the invention, ionic liquid is used as a liquid coolant. It has
a wide temperature range for liquid phase such as -100.degree. C.
to 400.degree. C. with very stable properties. It has no visible
vapor pressure, enabling high quality pumping performance.
[0023] In one embodiment, electromagnetic pump is used to drive the
ionic liquid coolant to circulate in the closed loop. The
electromagnetic pump is suitable for pumping ionic liquid coolant
without direct contacting. Other advantages include high
reliability and easy maintenance.
[0024] The liquid coolant conduit is directly merged into a river
or a conduit of river water or other large water bodies for a
simple structure and thus a low cost. Because natural water or
other large water bodies may have mud, particles, and other solid
impurities, a grate may be used to prevent dirty things attached on
the outer surface of the coolant conduit merged into water.
[0025] Cooling conduit merged into river will cause temperature
rise, but it is very limited, for example, three degrees, so that
this cooling method is environmentally benign.
[0026] In winter season of north area, temperature is so low in
north area that water in the large water body may freeze. In order
to avoid possible damage on conduits caused by freezing, the
conduits of the liquid coolant should have good protection such as
underground arrangement. Such ideas are also applicable to other
related parts like pumps.
[0027] The water level of the large water body changes with season
or time, especially when the large water body is a river. Special
attention should be paid for adjustment of the relative conduit
location.
BRIEF DESCRIPTION OF THE DRAWINGS
[0028] So that the manner in which the above recited features of
the present invention can be understood in detail, a more
particular description of the invention, briefly summarized above,
may be had by reference to embodiments, some of which are
illustrated in the appended drawings. It is to be noted, however,
that the appended drawings illustrate only typical embodiments of
this invention and are therefore not to be considered limiting of
its scope, for the invention may admit to other equally effective
embodiments.
[0029] FIG. 1 depicts one embodiment of computer cooling system
having regular ICs or 3D ICs in accordance with one embodiment of
the invention;
[0030] FIG. 2 depicts a schematic view of a regular IC cooling
method that may be utilized to cool the computer in accordance with
one embodiment of the present invention.
[0031] FIG. 3 depicts a schematic view of a 3D IC cooling method
that may be used for cooling computer in accordance with one
embodiment of the present invention.
DETAILED DESCRIPTION
[0032] Embodiments of the present invention generally provide
apparatus and methods for removing heat from a regular IC or 3D IC
computer system. Particularly, embodiments of the present invention
provide a simple and cost-effective method and apparatus for
removing heat from regular IC or 3D IC packages in computer system.
In one embodiment, a liquid coolant is disposed contacting to the
heat-generating IC components. The heat is carried out of the
electronic devices by liquid coolant and dissipated to a large
water body such as river, reservoir, or ocean.
[0033] FIG. 1 schematically illustrates a cooling system 100 in
accordance with one embodiment of the present invention. The
cooling system 100 generally comprises a building 102 configured to
accommodate computers. The cooling system 100 further comprises a
river 130 in connection with the building 102 via a supply conduit
148 and a return conduit 150.
[0034] The building 102 generally comprises a left sidewall 104, a
front sidewall 106, a right sidewall 108, a back sidewall 110, and
a roof 140. In one embodiment, the building 102 comprises first
floor 134 and second floor 136.
[0035] The cooling system 100 comprises a server rack 116 and a
server rack 118 on the first floor 134. The cooling system 100 also
includes a server rack 112 and a server rack 114 on the second
floor 136. A server rack usually accommodates multiple servers. In
one embodiment, the server rack 114 accommodates a server 120 and a
server 122.
[0036] The cooling system 100 is configured to position a liquid
coolant supply conduit 148 to flow a liquid coolant 138 into the
server 120 and carry heat out of the server 120 by flowing the
liquid coolant 138 out of the server 120 in the return conduit 150.
The liquid coolant supply conduit 148 and the return conduit 150
are connected to a merged conduit 160 to dissipate heat in the
liquid coolant 138 to the river stream 128 in the river 130. The
chip contact details will be further described below with
references in FIG. 2 and FIG. 3.
[0037] During cooling process, the supply conduit 148 has a higher
pressure compared with return conduit 150 to ensure the flow rate
for cooling performance. The liquid coolant 138 in the supply
conduit 148 has a lower temperature than the liquid coolant 138 in
the return conduit 150. The liquid coolant 138 in the return
conduit 150 transfers heat out of the server 120 to the water
stream 128 in the river 130. During the cooling liquid 138 flowing
through the emerged conduit 160, the temperature of the liquid
coolant 138 decreases and attains such a low temperature when
flowing out of the merged conduit 160 that the temperature meets
the requirement for flowing into heat-generating components in the
server 120.
[0038] The heat dissipation in the river 130 can be configured for
cooling of one server, or one server rack, or multiple server
racks. When heat dissipation is for cooling of multiple servers,
the constant pressures in the supply conduit 148 and the return
conduit 150 should be kept well. The liquid coolant 138 should be
stable and flow-rate controllable without bubbles to ensure the
quality of cooling and heat exchanging.
[0039] The heat exchange of the emerged conduit 160 in the river
130 may have high heat exchange efficiency due to the high density
of liquid. The temperature difference between the supply conduit
148 and the return conduit 150 is low to avoid high temperature
variation in heat-generating components in computer system. Typical
temperature difference between these two conduits is 10-30.degree.
C. The circulation of the liquid coolant 138 is driven by a pump
156 in order to have an acceptable heat exchanging rate on the
surface of heat-exchanging components.
[0040] During cooling processing of one embodiment for data center
located in north cold area, the supply conduit 148 and the return
conduit 150 are laid underground to avoid freezing in winter.
Similarly, the pump 156 should be protected well during winter for
data center located in north area.
[0041] According to one embodiment of the invention, a regulating
valve 154 is used to adjust the flow rate of the liquid coolant 138
by varying the opening.
[0042] In one embodiment, a grate and filter is used close to the
emerged conduit 160 to keep the contaminants out of the cooling
system. In addition, the elevation of the emerged conduit 160 for
heat exchanging in the river 130 may be adjusted according to the
level of river, especially in the north area where river water
level changes with season significantly.
[0043] For convenience of operation, the building 102 should be
located close to the river 130 to reduce the length of the
conduits. To ensure the performance of the cooling system 100, the
river current 128 should be high enough for cooling of a data
center. Generally, the river stream 128 should have a discharge of
40 m.sup.3/s or higher for cooling of a large data center.
[0044] In one embodiment, the liquid coolant 138 is deionized
water. In another embodiment, the liquid coolant 138 is oil or
ionic liquid.
[0045] FIG. 2 schematically illustrates an enlarged view of the
server 220 disposed in the server rack 114 of FIG. 1. The server
220 includes the board 201 configured to accommodate components.
The board 201 supplies mechanical holding to components and
electrical interconnection among the devices. The board 201 can be
a printed circuit board (PCB) or silicon interposer. In one
embodiment, the board 201 holds a MPU 203, a memory package 205, a
power-supply chip 207, and a memory storage 209. The server 220
also accommodates a supply conduit 248, a return conduit 250, a MPU
cooling conduit 213, a memory cooling conduit 215, a power cooling
conduit 217, and a store cooling conduit 219, wherein the liquid
coolant 238 flows for heat exchanging.
[0046] The cross-sectional areas of liquid conduits may vary for
cooling effectiveness. In one embodiment, the cross-sectional areas
of the supply conduit 248 and the return conduit 250 are
significantly larger than those of the MPU cooling conduit 213, the
memory cooling conduit 215, the power cooling conduit 217, and the
store cooling conduit 219.
[0047] During cooling processing, the liquid coolant 238 is
circulated in a closed loop shown in FIG. 1. Liquid conduits shown
in FIG. 2 are part of the total closed loop. In order to have
effective heat exchanges between devices and the liquid coolant
238, moderate flow rate in heat-generating components should be
kept. Generally, the turbulent flow in the MPU conduit 213, the
memory conduit 215, the power conduit 217, and the storage conduit
219 should be maintained. The pump 156 shown in FIG. 1 drives the
flow rate and ensures the effectiveness of heat dissipation.
[0048] Heat dissipation makes temperature in the return conduit 250
higher than that in the supply conduit 248. The higher temperature
difference between these two conduits means more energy carried out
at a same flow rate. However, low temperature difference should be
kept in order to have a more uniform temperature on the
heat-generating components. The non-uniformity of temperature may
introduce extra stress, resulting in reliability issues. Typical
temperature difference between the supply conduit 248 and return
conduit 250 is about 20.degree. C.
[0049] MPUs consume most power in a computer system. Effective
contact between the MPU conduit 213 and the MPU 203 is the key to
cool the MPU. The plane ship of the MPU 203 generally makes the
realization of thermal contact easy. However, common memory chips
are packaged in single in-line memory module (SIMM) or dual in-line
memory module (DIMM), which has a non-plane shape, resulting in
challenges in thermal contact effectiveness.
[0050] Recently, 3D ICs stacked by using through silicon via (TSV)
provide an effective way to make DRAM package have a plane
geometry. In one embodiment of this disclosure, stacked DRAM as the
memory package 205 is used for the server 220. Therefore, the
memory package 205 has a plane for obtaining effective thermal
contact between the liquid coolant 238 and the memory package
205.
[0051] Generally, power chip 207 is attached to a large radiator
for dissipating heat into air. In one embodiment of this invention,
the power conduit 217 will be attached to the power chip 207 for
effective heat dissipation.
[0052] Sometime, a server includes the storage 209. In one
embodiment, the storage 209 is a solid-state storage. In another
embodiment, the storage 209 is a hard driver. In any case, the
storage conduit 219 will provide effective heat dissipation.
[0053] In one embodiment, heat-generating components are modules,
but there are some passive components which release small amount of
heat. For releasing this heat, a cooling conduit may be thermally
contacted with the motherboard or interposer to dissipate heat.
[0054] FIG. 3 schematically illustrates an enlarged view of a
stacked 3D IC 321 of the server 120 disposed in the server rack 114
of FIG. 1. The 3D IC 321 includes a microprocessor 322, a memory
324, a microprocessor liquid conduit 354 configured to flow a
liquid coolant 338 thermally contacting with the microprocessor
322, a memory liquid conduit 352 configured to flow the liquid
coolant 338 thermally contacting the memory 324.
[0055] The microprocessor 322 has a front side 346, a back side
344, a device layer 332, a silicon layer 330, and a plural of TSV
334. Electricity is mostly consumed at the device layer 332, so
that this layer becomes the main heat-generating component. In one
embodiment, the liquid coolant 338 flows in the microprocessor
conduit 354 for carry out heat from the microprocessor 322.
[0056] In one embodiment, the memory 324 has a memory front side
340, a memory back side 342, a memory device layer 326, a memory
silicon layer 328, and a plural of memory TSV 336. The memory back
side 342 is bonded with the microprocessor back side 344 for
mechanical and electric interconnection between the microprocessor
322 and the memory 324.
[0057] The cross-sectional areas of liquid conduits impact cooling
effectiveness. In one embodiment, the cross-sectional areas of the
supply conduit 348 and the return conduit 350 are significantly
larger than those of the MPU liquid conduit 354 and the memory
liquid conduit 352.
[0058] During cooling processing, the liquid coolant 338 is
circulated in a closed loop shown in FIG. 1. Liquid conduits shown
in FIG. 3 are part of the total closed loop. In order to have
effective heat exchanges between heat-generating components and the
liquid coolant 338, moderate flow rate in liquid conduits of
heat-generating components should be kept. Generally, the turbulent
flow in MPU liquid conduit 354 and the memory liquid conduit 352
should be maintained. The pump 156 shown in FIG. 1 drives the flow
rate and the valve 154 controls the flow rate to ensure the
effectiveness of heat dissipation.
[0059] Heat dissipation makes temperature in the return conduit 350
higher than that in the supply conduit 348. The higher temperature
difference between these two conduits means more energy carried out
at a same flow rate. However, low temperature difference should be
kept in order to have a more uniform temperature on the
heat-generating components. The non-uniformity of temperature may
introduce extra stress, resulting in reliability issues. Typical
temperature difference between the supply conduit 348 and return
conduit 350 is about 20.degree. C.
[0060] MPUs consume most power in a computer system. Effective
contact between the MPU liquid conduit 354 and the MPU 322 is the
key to cool the MPU. The plane ship of the MPU 322 generally makes
the realization of thermal contact easy. However, common memory is
packaged in single in-line memory module (SIMM) or dual in-line
memory module (DIMM), which has a non-plane shape, resulting in
challenges in thermal contact effectiveness.
[0061] Recently, 3D ICs stacked by using TSV provide effective way
to make DRAM package have a plane geometry. In one embodiment of
this invention, stacked DRAM as the memory 324 is used for the
stacked 3D IC 321. Therefore, the memory 324 has a plane for
obtaining effective thermal contact with the liquid coolant
338.
[0062] In one embodiment, heat-generating components are modules,
but there are some passive components which release small amount of
heat. For dissipating this heat, a cooling conduit may be thermally
contacted with the motherboard or interposer to dissipate heat.
[0063] While the foregoing is directed to embodiments of the
present invention, other and further embodiments of the invention
may be devised without departing from the basic scope thereof, and
the scope thereof is determined by the claims that follow.
* * * * *