Electricity: electrical systems and devices – Housing or mounting assemblies with diverse electrical... – For electronic systems and devices
Reexamination Certificate
1999-01-22
2002-06-11
Picard, Leo P. (Department: 2835)
Electricity: electrical systems and devices
Housing or mounting assemblies with diverse electrical...
For electronic systems and devices
C361S688000, C361S689000, C361S698000, C361S699000, C361S701000, C361S719000, C174S015100, C165S080400
Reexamination Certificate
active
06404640
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to an electronic apparatus used in a computer system, or the like.
2. Description of the Related Art
A computer system comprises an arithmetic operation section with integrated arithmetic circuits, a cache section operating at a high speed, for processing instructions and data, so as not to reduce the processing capacity of the arithmetic operation section, a memory section for storing the instructions and data sent to the cache section, and peripheral units for reading programs and data from the memory. Also, a system having a plurality of arithmetic operation sections for concurrent operation comprises a common memory section accessible by a plurality of arithmetic operation sections. Especially, the arithmetic operation section and the cache section operate at a high clock frequency in order to improve the operating speed, and involve considerable data changes for large power consumption and heat generation.
Means for cooling these circuits include natural air cooling, forced air cooling, liquid cooling, immersion cooling, etc. Natural air cooling is low in cooling capacity and used for small computers which generate a small amount of heat. Forced air cooling and liquid cooling are used for computers having a high processing capacity. The main application of immersion cooling is to special computers, in test stages, using the Josephson device or the like.
The mainframe computer, as shown in
FIG. 47
, has a large arithmetic operation circuit, which is configured of a motherboard
201
having a plurality of LSIs
203
mounted thereon. This motherboard generates so much heat that it is cooled by a cooling plate which, in turn, is cooled by a cooling liquid. The cooling plate
206
includes bellows
207
on the portion thereof in opposed relation to the LSIs
203
which generate heat. These bellows
207
are brought into contact with the LSIs
203
to cool the latter. The refrigerant used for this cooling plate
206
is cooled down to about room temperature by a heat exchanger (not shown). The refrigerant absorbs the heat of the LSIs
203
and returns to a heat exchanger not shown. Also, the bellows
207
have a spring property to closely contact the LSIs
203
, so that the LSIs
203
and the bellows
207
can thermally contact each other simply by mounting the cooling plate
206
at a predetermined position on the motherboard
201
.
This apparatus has LSIs
203
mounted on the two sides of the motherboard
201
, though not shown, in order to improve the package density. In order to cool the LSIs
203
mounted on the two sides, two cooling plates
206
are arranged on both sides of the motherboard
201
. As a result, when the motherboard develops an abnormality or the requirement for replacement occurs due to the version up of hardware, it is necessary to remote the cooling plate
206
from the housing and then remove the motherboard
201
.
Also, with the improvement in the performance of this apparatus and with the increase in the processing capacity of the LSI
203
, more heat is generated. To increase the flow rate of the cooling water, however, a lower pressure resistance in the cooling plate, piping, etc. is required. However, the cooling plate, or the like, is arranged in a limited space and it is impossible to increase the size. If the temperature of the cooling water is decreased below room temperature, on the other hand, water drips attach to the motherboard, thereby causing a malfunction. The area at which the motherboard
201
and the cooling plate
206
are thermally connected to each other is limited to the contact area between the LSIs
203
and the bellows
207
. To increase this area, a total change of the apparatus structure is required and this is difficult. For improving the cooling performance, therefore, the thermal resistance at the contact surface must be decreased. If the bellows
207
is pressed against the LSIs
203
with a greater force, the LSIs
203
and the motherboard
201
would be damaged. Also, a larger force would be required for mounting the cooling plate
206
for deteriorated maintainability. In view of this, a metal of low melting point is held between the LSIs
203
and the bellows
207
and melted to mount and demount the cooling plate. In this way, the contacting force is increased for a reduced thermal resistance.
As a result, each time the motherboard is replaced or the cooling plate is mounted or demounted, the bothersome labor of spraying hot air higher in temperature than the melting point of the metal between the motherboard and the cooling plate is required for a very deteriorated maintenance efficiency.
With the advance in CMOS techniques, the present-day mainframe computer uses forced air cooling using radiation fins
204
, as shown in
FIG. 48. A
circuit as large as the arithmetic operation circuit mounted on the motherboard
201
in
FIG. 47
is formed of one chip by the recently-developed micromachining technology. Thus, the arithmetic operation circuit which has conventionally been configured of a plurality of motherboards is now formed of a single multi-chip module
202
. Further, the reduced size of the circuit has shortened the signal line and operation with higher clock frequency is made possible. At the same time, the power saving unique to the CMOS technique eliminates the need for liquid cooling. In this way, the operation capacity of each motherboard
201
has been remarkably improved while the conversion of the cooling method from liquid cooling to forced air cooling has improved the maintenance efficiency.
The change in cooling method from liquid cooling to forced air cooling has eliminated the need of installing the cooling plate and makes it possible to replace the motherboard directly. Also, since there is no need of piping work, the radiation fins can be divided into small units on the motherboard, and the radiation fin can be installed on each multi-chip module constituting a unit of parts on the motherboard. As a result, the multi-chip module can be handled with the radiation fin mounted thereon, and parts can be replaced without removing the cooling plate or the motherboard.
Even with the recent technological development, however, the reduction in circuit size and the operation at a high clock frequency due to the reduced circuit size have reached a limit. As disclosed in JP-A-1-318295, it is known that a semiconductor device can operate at a higher rate of reaction and a higher clock frequency, when the temperature thereof is lower. It is, therefore, unavoidable to introduce such a technique for meeting the prevailing requirement of the processing performance. The technique of cooling the semiconductor devices, which generally includes natural air cooling, forced air cooling and liquid cooling, is the one for preventing the thermal breakdown due to the heat generated in the semiconductor itself. Immersion cooling, on the other hand, which is used for cooling the Josephson device or the like, is realized as a cooling method for maintaining the operating temperature of the device, but the application of this technique to computers in general is difficult due to the maintenance problem.
SUMMARY OF THE INVENTION
The object of the present invention is to provide a practical cooling structure, taking maintainability into consideration, in which a semiconductor circuit is cooled to its operating temperature adapted for operation at a high clock frequency.
An electronic apparatus according to this invention comprises a motherboard, multi-chip modules mounted to the motherboard, cooling members for cooling the multi-chip modules, a refrigeration unit for cooling the cooling members to the room temperature or lower, and a connection structure provided for each multi-chip module for thermally and mechanically releasibly coupling each multi-chip module to the refrigeration unit.
The cooling members can be mounted and dismounted while the multi-chip modules are being mounted to the motherboard. As a result, the motherboard can be eas
Fujisaki Akihiko
Ishimine Junichi
Kawashima Hisashi
Miyo Masahiro
Mochizuki Masahiro
Armstrong Westerman Hattori McLeland & Naughton LLP
Fujitsu Limited
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