Cooling apparatus for electronic equipment

An electronic equipment has a cooling structure in which air discharged from heat sinks can be recovered without any leakage and compact blow ducts and discharge ducts are disposed in a narrow space. A supply opening and a discharge opening for cooling air are independently formed in a heat sink. A plurality of supply branched ducts and discharge branched ducts are combined in a comb-like shape along the axis of the ducts. Ejection openings for cooling air are formed on each of the supply branched ducts in positions corresponding to each of the heat sinks. Such ejection openings are closely connected to the supply openings for cooling air of the heat sinks. On the other hand, recovery openings for cooling air are formed on each of the refrigerant discharge ducts in a position corresponding to each of the heat sinks. Such recovery openings are closely connected to the discharge openings for gas refrigerant of the heat sinks.

BACKGROUND OF THE INVENTION 
1. Field of the Invention 
The present invention relates to an electronic equipment having a plurality 
of heat-emitting semiconductor parts in which a refrigerant such as air, 
or the like, flows to cool the semiconductor parts by means of heat sinks. 
More particularly, the invention relates to an electronic equipment having 
the feature of the cooling structure, such as the heat sinks. 
2. Description of the Related Art 
Conventionally, the following system is often employed in an electronic 
equipment as a means of cooling a plurality of heat-emitting semiconductor 
parts mounted on a circuit substrate such as a printed substrate, a 
ceramic substrate, or the like. A fin is mounted on each of the 
heat-emitting semiconductor parts, thereby supplying cooling air to the 
sides of the semiconductor parts which are then sequentially cooled. 
However, since the amount of heat emitted from the semiconductor parts 
continues to significantly increase, the above system presents a new 
problem in that the air temperature thus soars, and accordingly, in the 
further the position of the equipment in the downstream direction of the 
air, the more the cooling performance deteriorates. Thus, in order to 
solve the above problem, the following method has been proposed. A fin is 
mounted on each of the heat-emitting semiconductor parts and the cooling 
air supplied from a blower is blown into each of the fins through a plenum 
and a nozzle, or the like, disposed on each of the fins. Then, the air 
which has been made warm in each of the fins is recovered in a discharge 
duct and then discharged therefrom. Such a method is disclosed in, for 
example, Japanese Utility Model Unexamined Publication No. 1-73993. A 
cooling equipment of such a conventional electronic equipment will be 
described with reference to FIG. 13. 
A plurality of heat-emitting LSIs 102 are mounted on a substrate 101. A 
heat sink 103 is further disposed on each of the LSIs 102. The cooling air 
is then supplied to each of the LSIs 102 from an inlet opening 106, 
through a blow duct 104 and an ejection opening 105, thereby cooling the 
LSIs 102. After cooling the LSIs 102, the cooling air stream is inverted 
in each of the heat sinks 103 and drawn into by a fan from into feedback 
openings 108 provided for discharge ducts 107 so as to be discharged via 
outlet opening 10 to the exterior of the equipment. 
The ejection openings 105 and the feedback openings 108 are separated from 
the heat sinks 103. Further, the discharge ducts 107 and the flow ducts 
104 are mounted on the heat sinks 103 in two stages. 
In the above conventional electronic equipment, when the amount of heat 
emitted from the semiconductor parts and the mounting density thereof are 
relatively small, all the cooling air can be substantially transferred to 
the heat sinks without any leakage, and all the air discharged from the 
heat sinks can be substantially recovered from the feedback openings and 
discharged to the exterior of the equipment. However, recently, the 
processing speed of electronic equipment has become higher and the density 
thereof has become larger, thereby increasing the amount of heat emitted 
from the semiconductor parts and the mounting density thereof and further 
increasing the air flow rate, thus raising the ejection pressure thereof 
and the discharge pressure from the heat sinks. Hence, the air discharged 
from the heat sinks may be leaked from a gap between each of the heat 
sinks and the feedback openings, thus making it difficult to recover the 
discharge air from the feedback openings without any leakage. It makes the 
matter worse that the unrecovered air is warm and thus increases the 
temperature of the other semiconductor parts or makes the air stream 
complicated, thereby increasing the flow loss and thus hampering efficient 
air cooling performed on the electronic equipment. 
Moreover, in the conventional electronic equipment, the discharge ducts are 
disposed on the top of the heat sinks provided for the semiconductor parts 
mounted on the substrate, and the blow ducts are further disposed on the 
top of discharge ducts. When the electronic equipment is constructed as 
described above, a considerably large space is required on top of the heat 
sinks. There is no problem when the semiconductor chips are arranged in a 
plane having a sufficiently large space on top of the heat sinks. However, 
when a plurality of substrates are three-dimensionally disposed closely 
parallel to each other, a sufficiently large space cannot be provided on 
top of the heat sinks, thus making it difficult to arrange the ducts 
constructed as described above. 
SUMMARY OF THE INVENTION 
Accordingly, in view of the above problems inherent in the related art, a 
first object of the present invention is to provide a cooling structure 
which is capable of recovering air discharged from heat sinks without any 
leakage even when the heat emitted from semiconductor parts and the 
mounting density thereof are increased and accordingly, the flow rate, 
ejection pressure and discharge pressure of air are increased. 
A second object of the present invention is to provide a cooling structure 
which is capable of providing compact blow ducts and discharge ducts in a 
narrow space when a large space for ducts cannot be ensured in the case 
where a plurality of substrates are disposed closely parallel to each 
other three-dimensionally. 
In order to achieve the first object, according to the present invention an 
electronic equipment is provided by constructing, a heat sink thermally 
connected to each of semiconductor parts and mounted thereon, the heat 
sink having a supply opening and a discharge and including a supply of 
branched duct for supply the gas refrigerant to the heat sink opening. The 
supply branched ducts are disposed on the extension along the arrangement 
of the heat-emitting semiconductor equipments. Each of the supply branched 
ducts includes ejection openings for the gas refrigerant in a position 
corresponding to each of the heat sinks. Such ejection openings are 
closely connected to the supply openings of the heat sinks. Then, the 
discharge branched ducts for recovering the refrigerant discharged from 
the heat sinks and discharging it to the exterior of the equipment are 
disposed on the extension along the arrangement of the semiconductor 
parts. Further, each of the discharge branched ducts has recovery openings 
in a position corresponding to each of the heat sinks. Such recovery 
openings are closely connected to the discharge openings of the heat 
sinks. 
In order to achieve the second object, the present invention provides an 
electronic equipment in which the refrigerant supply branched ducts and 
refrigerant discharge branched ducts are alternately disposed in the same 
plane substantially parallel to the substrates along gaps between 
heat-emitting semiconductor parts. 
Also, the refrigerant supply branched ducts may supply a refrigerant to two 
or more heat sinks in a cross section vertically taken along the axis of 
the ducts. 
Moreover, the refrigerant discharge branched ducts may recover a 
refrigerant from two or more heat sinks in a cross section vertically 
taken along the axis of the ducts. 
Further, the height of the heat sinks may become smaller toward the end 
thereof so that the refrigerant supply branched ducts and discharge 
branched ducts are alternately disposed to fill in the gaps between the 
adjacent heat sinks. 
The present invention also provides an electronic equipment in which a 
plurality of heat-emitting semiconductor parts are mounted on both 
surfaces of a substrate and a plurality of substrates are stacked 
substantially parallel to each other, wherein a quadrilateral portion is 
formed by two of the adjacent semiconductor parts mounted on one surface 
of the substrate and another two of the adjacent semiconductor parts 
mounted on another substrate facing the surface of the former substrate in 
the position facing the former semiconductor parts, a refrigerant supply 
branched duct for simultaneously supplying a gas refrigerant to the four 
semiconductor parts being disposed in the quadrilateral portion. 
The present invention further provides an electronic equipment in which a 
plurality of heat-emitting semiconductor parts are mounted on both 
surfaces of a substrate and a plurality of substrates are stacked 
substantially parallel to each other, wherein a quadrilateral portion is 
formed by two of the adjacent semiconductor parts mounted on one surface 
of the substrate and another two of the adjacent semiconductor parts 
mounted on another substrate facing the surface of the former substrate in 
the position facing the former semiconductor parts, a refrigerant 
discharge branched duct for simultaneously recovering a gas refrigerant 
from the four semiconductor parts being disposed in the quadrilateral 
portion. 
Also, the sectional area vertically taken along the axis of the refrigerant 
supply ducts may be made smaller toward the downstream direction in which 
the refrigerant flows. 
Further, the sectional area vertically taken along the axis of the 
refrigerant discharge ducts may be made larger toward the downstream 
direction in which the refrigerant flows. 
According to the above construction of the present invention, the following 
advantages can be obtained. 
Even when the amount of heat emitted from the semiconductor parts and the 
mounting density thereof are greater, and accordingly, the air flow rate 
for cooling the semiconductor parts and the ejection pressure are 
increased, the air ejection openings of the refrigerant supply branched 
ducts are closely connected to the supply openings of the heat sinks, thus 
supplying the air to the heat sinks without any leakage. On the other 
hand, the air recovery openings of the refrigerant discharge branched 
ducts are adjacent to the discharge openings of the heat sinks, thus 
recovering the discharge air from the heat sinks without any leakage and 
further discharging it to the exterior of the equipment. Consequently, the 
cooling air can be employed for heat exchange without any waste, and also 
the warming of the cooling air due to such leakage is prevented, thus 
avoiding an increase in the temperature of other semiconductor parts and 
further enabling uniform and highly-efficient air cooling. Also, a 
complicated air stream due to air leakage is not produced, thereby 
smoothly enhancing efficient air flowing and reducing a flow loss. 
Also, the refrigerant supply branched ducts and discharge branched ducts 
are alternately arranged on the same surface parallel to the substrates, 
thereby forming a compact duct system perpendicular to the substrates. 
Thus, even when a plurality of substrates are disposed closely parallel to 
each other three-dimensionally, a compact and efficient cooling structure 
can be realized. 
Further, when the branched ducts are formed, the refrigerant supply 
branched ducts are capable of simultaneously supplying the air to a 
plurality of heat sinks in a cross section vertically taken along the axis 
of the ducts in the air-flowing direction. On the other hand, the 
refrigerant discharge branched ducts are capable of simultaneously 
recovering the air from the plurality of heat sinks. As a result, the 
electronic equipment of the present invention can be constructed more 
simply and also the flow loss can be reduced more than an equipment in 
which each of the sets of refrigerant supply and discharge ducts is only 
allocated to one heat sink. 
Even when there is almost no space for disposing the refrigerant supply and 
discharge branched ducts above the heat sinks provided with the 
semiconductor parts mounted on the substrate, both ducts can be 
alternately disposed in the gaps between the adjacent heat sinks. 
Consequently, even when a plurality of substrates are very closely 
parallel to each other three-dimensionally, the air cooling can be 
realized in high efficiency. 
Moreover, even when a plurality of substrates having mounted on both 
surfaces thereof the semiconductor parts are disposed very closely 
parallel to each other, both ducts can be alternately arranged in a 
rhombic space surrounded by the four heat sinks adjacent to each other, 
thus enabling the air cooling in high efficiency. 
Still further, the sectional area taken along the axis of the ducts are 
changed, thereby achieving the uniform air flow velocity in the 
refrigerant supply branched ducts or the refrigerant discharge branched 
ducts, thus further reducing the pressure loss and enabling the uniform 
distribution of the flow rate into the respective heat sinks.

DESCRIPTION OF THE PREFERRED EMBODIMENTS 
The present invention will now be described with reference to FIGS. 1-11. 
A first embodiment of an electronic equipment according to the present 
invention is shown in FIGS. 1-6. FIG. 1 is a sectional view of the 
electronic equipment of this embodiment as viewed from the bottom to the 
top of the equipment. FIG. 2 is a sectional view of the electronic 
equipment of this embodiment as viewed from the side of the equipment. 
Referring to FIG. 1, a plurality of heat-emitting semiconductor parts 2 
representative of electronic circuit modules, LSIs, or the like, are 
arranged close to each other on both surfaces of each of substrates 1, 
such as printed wiring substrates or ceramic substrates. The plurality of 
substrates 1 are disposed parallel to each other at predetermined spacing 
to be three-dimensionally mounted thereon. A heat sink 3 is mounted on 
each of the heat-emitting semiconductor parts 2 to effectively conduct the 
heat emitted from each of the semiconductor parts 2 to cooling air. Each 
of the heat sinks 3 is constructed in the form of a fin, for example, a 
plane-parallel plate fin, pin fin, fibrous fin, corrugate fin, or in the 
form of a heat pipe or a thermo-syphon including a built-in operation 
fluid for transferring heat by utilizing the transformation of phases. 
Further, each heat sink 3 is shaped such that its width is narrower toward 
the top (the triangular shape in FIG. 1). Further, an air supply opening 
and a discharge opening are formed in the heat sink 3 independently of 
each other. It is desirable that the heat sink 3 be formed of a material 
having good heat conductivity, such as copper, aluminium, or highly 
heat-conductive ceramic. The heat-emitting semiconductor parts 2 and the 
heat sinks 3 are each constructed to thermally contact each other via a 
heat-conductive grease, a heat-conductive sheet or a heat-conductive 
adhesive, or to simply contact by pressing against each other by means of 
a screw. A gap between two of the adjacent heat sinks 3 on the same 
substrate 1 and another gap between two of the adjacent heat sinks 3 on 
the facing substrate form a rhombic space. Air supply branched ducts 4 and 
air discharge branched ducts 5 having the same rhombic cross sections are 
alternately disposed to be accommodated in such rhombic spaces. 
Referring to FIG. 2, the supply branched ducts 4 and the discharge branched 
ducts 5 are extended from a supply chamber 7 and a discharge chamber 11, 
respectively, in a comb-like form in such a way that the comb teeth are 
engaged with each other. Supply blowers 8 for supplying cooling air are 
connected to the supply chamber 7, and discharge blowers 12 for 
discharging the discharge air are connected to the discharge chamber 11. 
The cooling air in the form of an air stream 9 is drawn into each of the 
supply blowers 8 from the exterior of a casing of the electronic equipment 
and pressurized therein so as to be fed into the supply chamber 7. The 
cooling air in the form of an air stream 10 is then split into the 
respective supply branched ducts 4 in which part of the air in the form of 
an air stream 6 flows into four of the heat sinks 3, two each on the right 
and left sides, and the rest of the air flows upward. This operation is 
repeated in the respective air flowing directions. On the other hand, the 
cooling air in the discharge branched ducts 5 flows upwardly while 
recovering the discharged air from the above four heat sinks 3. It is fed 
into the discharge chamber 11 in the form of an air stream 13 and drawn 
into each of the discharge blowers 12 in the form of an air stream 14 so 
as to be finally discharged to the exterior of the casing of the 
electronic equipment in the form of discharged air 15. 
FIG. 3 is a detailed sectional view of the electronic equipment of the 
embodiment shown in FIG. 1 as viewed from the bottom to the top of the 
equipment. FIG. 4 is a detailed perspective view of the heat sinks 3. As 
shown in FIG. 3, four ejection openings 18 and four recovery openings 19 
are provided for the air supply branched duct 4 and the air discharge 
branched duct 5, respectively. Each of the widths of the ejection openings 
18 may be narrowed in order to supply a high-speed air jet 16 into the 
heat sinks 3, thereby increasing heat conductivity due to the air jet and 
thus improving cooling performance. Each of the heat sinks 3 is provided 
with, for example, a row of triangular flat plate fins 20 and a base plate 
21, as illustrated in FIG. 5. As shown in FIG. 4, an air supply opening 23 
is formed on the end surface adjacent to the air supply branched duct of 
each of the heat sinks 3 by two covering plates 22. The supply opening 23 
and the ejection opening 18 of each of the air supply branched ducts 4 are 
closely connected to each other in order to avoid leakage of the cooling 
air. 
Likewise, an air discharge opening 26 is formed on the end surface adjacent 
to the air discharge branched duct of each of the heat sinks 3 by two 
covering plates 25. The discharge opening 26 and the recovery opening 19 
of each of the air discharge branched ducts 5 are closely connected to 
each other so that discharge gas 17 from the heat sink 3 can be recovered 
without any leakage. 
FIGS. 6 and 7 are perspective views of the electronic equipment of the 
embodiment shown in FIG. 1 for illustrating the manner of assembling the 
equipment. As illustrated in FIG. 6, the semiconductor parts 2, each 
having mounted thereon a heat sink 3, are mounted on both surfaces of the 
mounting substrates 28 in a grid-like form. The air supply branched ducts 
4 and the air discharge branched ducts 5 are alternately disposed between 
the surfaces of the mounting substrates 28. As shown in FIG. 7, two of the 
mounting substrates 28 are combined in order to closely connect the air 
supply branched ducts 4 with the heat sinks 3 and the air discharge 
branched ducts 5 therewith. When three or more of the mounting substrates 
28 are provided parallel to each other, the electronic equipment can also 
be similarly assembled. 
In this embodiment, since the air recovery openings of the refrigerant 
discharge ducts and the air discharge openings of the heat sinks 3 are 
closely connected to each other, the discharged air from the heat sinks 3 
can be recovered without any leakage and discharged to the exterior of the 
equipment. Consequently, the cooling air can be employed for heat exchange 
without any waste, and also warming of the cooling air due to such leakage 
is prevented, thus avoiding an increase in the temperature of other 
semiconductor parts, and further enabling uniform and highly-efficient air 
cooling. Also, a complicated air stream due to air leakage is not 
produced, thereby enhancing smoothly air flowing and reducing flow loss. 
Moreover, even if there is almost no space for accommodating the supply 
branched ducts 4 and the discharge branched ducts 5 above the heat sinks 3 
provided for the semiconductor parts mounted on the substrate 1, both 
ducts can be disposed alternately in the gaps between the heat sinks 3. 
Hence, even-when a plurality of substrates 1 are provided very closely 
parallel to each other three-dimensionally, the air cooling can be 
realized in high efficiency. 
Further, the supply branched duct 4 is capable of simultaneously supplying 
the air to a plurality of heat sinks 3 in a cross section vertically taken 
along the axis of the duct, and the discharge branched duct 5 is capable 
of simultaneously recovering the air from the plurality of heat sinks 3. 
As a result, the electronic equipment of the present invention can be 
constructed more simply, and also the flow loss can be reduced more than 
on equipment in which each of the sets of supply and discharge ducts is 
allocated to only one heat sink. 
A second embodiment of the electronic equipment will now be described with 
reference to FIG. 8. FIG. 8 is a detailed sectional view of the electronic 
equipment of this embodiment as viewed from the bottom to the top of the 
equipment. In this embodiment, a base plate for a plurality of heat sinks 
3 is commonly used. Each of the common base plates 31 is thermally brought 
into contact with a plurality of semiconductor parts 2 and mounted 
thereon. The heat sinks 3 are each disposed on the top surface of the 
common plate 31 in a position corresponding to one of the semiconductor 
parts 2. Thus, the plurality of heat sinks 3 can be replaced by a single 
part, thereby reducing the number of parts and further enabling a 
reduction in cost and the number of assembly processes. Although each of 
the heat sinks 3 is disposed in a position corresponding to one of the 
semiconductor parts 2 in this embodiment, the heat sinks 3 are not 
restricted to this position in this embodiment. Also, according to the 
amount of heat of the equipment and the space thereof, a plurality of heat 
sinks may be provided for one semiconductor part, or conversely, a 
plurality of semiconductor parts may be provided with one heat sink. 
A third embodiment of the electronic equipment is shown in FIG. 9. FIG. 9 
is a detailed sectional view of the electronic equipment as viewed from 
the bottom to the top of the equipment. In this embodiment, the 
semiconductor parts 2 are mounted on only one surface of the substrate 1, 
and in such a case, each of the air supply branched ducts 4 and the 
discharge branched ducts 5 has an inverted triangular section. However, 
advantages of this embodiment similar to those in the first embodiment can 
be obtained. 
A fourth embodiment of the electronic equipment is shown in FIG. 10. FIG. 
10 is a view combining a sectional view of the electronic equipment of 
this embodiment as viewed from the side of the equipment with sectional 
views of the same equipment as viewed from the bottom and the top thereof. 
In this embodiment, the air supply branched ducts 4 are constructed to be 
tapered in such a way that each sectional area of the ducts in a cross 
section vertically taken along the axis of the duct is reduced toward the 
downstream thereof in the air flowing direction. On the other hand, the 
air discharge branched ducts 5 are constructed to be diverged in such a 
way that each sectional area of the ducts in a cross section vertically 
taken along the axis of the duct is enlarged toward the downstream thereof 
in the air flowing direction. The apex of each of the triangular heat 
sinks 3 is displaced along the axis of the duct, along with the shape of 
the tapered supply ducts and that of the diverged discharge ducts. Since 
the electronic equipment is constructed as described above, the air flow 
velocity in the supply and discharge ducts can be uniform and the pressure 
loss in the ducts can thus be reduced. Also, the air flow can be uniformly 
distributed into the vertically-disposed heat sinks. 
A fifth embodiment of the electronic equipment is shown in FIGS. 11 and 12. 
FIG. 11 is a sectional view of the electronic equipment of this embodiment 
as viewed from the bottom to the top of the equipment. FIG. 12 is a 
detailed perspective view of the heat sink of this embodiment. This 
embodiment is effective when gaps between a plurality of substrates 1 are 
relatively large, in which case, the air supply branched ducts 4 and the 
discharge branched ducts 5 are disposed only on the heat sinks 3. For 
example, large rectangular heat sinks shown in FIG. 11 can be accommodated 
in the relatively large gaps between the plurality of substrates 1. A 
space is also secured between the facing heat sinks 3, the supply and 
discharge ducts 4 and 5 being disposed alternately therein. As illustrated 
in FIG. 12, each of the rectangular heat sinks 3 comprises, for example, 
flat plate fins 34. Supply openings 23 and discharge openings 26 are 
arranged only on top of the flat plate fins 34. Partitions 32 of the heat 
sink 3 are disposed around the flat plate fins 34 in order to avoid the 
leakage of air. The supply openings 23 and the discharge openings 26 are 
separated by another partition 33 between the supply and discharge ducts. 
Since the electronic equipment is constructed as described above, in 
addition to the advantages obtained in the previous embodiments, cooling 
performance is advantageously improved because of the large heat sinks, 
and the supply and discharge ducts can be made larger, thus reducing the 
pressure loss. Further, since the air supply and discharge ducts can be 
built integrally with each .other, the number of parts can be decreased, 
thus reducing the number of processes. 
As will be clearly understood from the foregoing description, the present 
invention offers the following advantages. 
Since the air recovery openings of the refrigerant discharge ducts and the 
air discharge openings of the heat sinks are closely connected to each 
other, the discharged air from the heat sinks can be recovered without any 
leakage and discharged to the exterior of the equipment. Consequently, the 
cooling air can be employed for heat exchange without any waste, and also 
warming of the cooling air due to such leakage is prevented, thus avoiding 
an increase in the temperature of other semiconductor parts and further 
enabling uniform and highly-efficient air cooling. Also, a complicated air 
stream due to air leakage is not produced, thereby smoothly enhancing 
efficient air flowing and reducing flow loss. 
Moreover, even if there is almost no space for accommodating the supply and 
discharge branched ducts above the heat sinks provided for the 
semiconductor parts mounted on the substrate, both ducts can be disposed 
alternately in the gaps between the heat sinks. Hence, even when a 
plurality of substrates are provided very closely parallel to each other 
three-dimensionally, the air cooling can be realized in high efficiency.