JPH1012781A - Forced cooling heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a forced cooling heat sink and a cooling construction using the heat sink capable of cooling so as to make the temperature of a heating member constant by efficiently radiating heat from a large heat generating member and capable of cooling a small heat generating member arranged in the downstream of the heat generating member in cooling a cabinet body such as electronic equipment. SOLUTION: A parallel flow type cooling structure blows a cooling medium 1 in parallel direction with the wiring circuit board to a wiring circuit board 50 where a sheet generating member is located, and a small heat generating member 40 is arranged in the downstream of a heat generating member 30 where a heat sink is arranged. To assure efficiently hitting cool air to the heat generating member 40, a guiding plate 10 is provided for changing the direction of air flow between fins to the surface in the downstream the heat sink 20.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an electronic device having a heat-generating member such as a semiconductor device, and more particularly to a semiconductor device and a multi-chip which are heat-generating members arranged on one or more wiring boards laminated in the housing of the electronic device. The present invention relates to a cooling structure for a module, and more particularly to a heat sink for forced cooling for efficiently cooling a plurality of heat generating members mounted on a wiring board at high density.

[0002]

2. Description of the Related Art In recent years, in electronic devices such as computers, there has been a strong demand for improvements in processing capability, miniaturization, cost reduction, and the like. Tend to. On the other hand, as the size of the housing is reduced, the heat generation density inside the housing is greatly increased. In addition, in order to reduce signal propagation delay time, a mounting form of a multi-chip module in which a large number of chips are mounted on a wiring board such as a ceramic and cooled collectively is often used for a semiconductor element for arithmetic processing. . The heat generation and heat density of the multi-chip module are both large, and cooling of the multi-chip module itself is also important. However, in the case of air cooling, the air heated by the multi-chip module greatly affects the surrounding heat generating members.

Heretofore, two large structures have been adopted as a blower structure for air-cooling a high-density mounting system in which a plurality of multi-chip modules, other semiconductor elements, and other heat-generating components that generate large heat are mixed. One is a parallel flow type cooling structure that blows cooling air to a heat generating member such as a semiconductor element mounted on the wiring board in a direction substantially parallel to the wiring board using a blower such as a blower or a fan. is there. The other is a jet-type cooling structure in which cooling air impinges on a multi-chip module or a specific heat-generating member that generates a large amount of heat in a substantially vertical direction toward a wiring board on which they are arranged.

[0004] Each heat generating member must be kept at a rated temperature or lower so as not to damage or malfunction the device due to an excessive rise in temperature. 2. Description of the Related Art In cooling electronic devices, there are many structures using a heat sink that increases a heat radiation area to improve cooling performance. In particular, a heat-generating member such as a semiconductor element or a multi-chip module that generates a large amount of heat is provided with forced cooling heat sinks having various shapes and sizes according to the heat generation density and the specification temperature.
The heat sink is made of a material having high thermal conductivity, such as aluminum or copper, and is generally a flat fin-type heat sink in which a plurality of parallel flat plates are stacked on a single metal flat plate at intervals of about 1 to 3 mm (FIG. 11A). ) Is often used. The flat fin is relatively easy and inexpensive to manufacture, and has the advantage of having a small pressure loss in spite of having a large heat dissipation area. Many are used.

[0005] In recent years, in addition to increasing the heat generation density, there has been an increasing tendency of mixed mounting in which semiconductor elements having different sizes are arranged adjacent to each other in the flow direction of the cooling medium inside the housing. One of the issues when air-cooling mixedly mounted electronic devices is that they are small and low in height, located downstream of large, high heat generating members, such as multi-chip modules. Deterioration of the cooling performance of the heat generating member is mentioned. On the downstream side of the large and high heat generating member, the flow velocity is low, and conversely, a region with a high wind temperature is formed in a wide range. If a small, low-height heat generating member is arranged in this area, its cooling performance will be significantly degraded.

As described above, a plurality of heat generating members having completely different sizes and heights are mixed on a wiring board, and a mounting form arranged downstream of the large heat generating member has recently been widely used. For this reason, sufficient cooling cannot be achieved simply by installing the flat fin type heat sink shown in FIG. 11A for each heat generating member. For this reason, as shown in FIG. 11B, an example of a structure for improving the cooling performance by changing the direction of the flow so that the cooling air flowing over the heat sink is collected in the fin portion (JP-A-6-188).
No. 340). In addition, JP-A-1-204498, JP-A-5-259325, and JP-A-6-163711 all disclose an upper or side portion of a heat sink provided on a heat generating member to be cooled. The structure is such that the flow of the passing cooling air is concentrated on the fins.

[0007]

In the conventional cooling structure using a heat sink (FIG. 11), when heat-generating members having different sizes are mounted at a high density, the small heat-generating members on which the heat sink is not installed are not cooled and malfunction. And so on. For this reason, it is necessary to install a heat sink on each of the heat generating members, and to suppress the trouble due to insufficient cooling. The heat sink of FIG. 11 has a structure in which a semiconductor element or a multi-chip module which is a heat generating member of an electronic device or the like is cooled independently. It does not contribute to the cooling of the smaller heating member installed on the side (exit side). For this reason, it is necessary to install a heat sink on other small heat generating members, and to design a cooling structure in consideration of the specification temperature.

SUMMARY OF THE INVENTION It is an object of the present invention to provide a cooling structure for electronic equipment including electronic equipment and various other heat generating members mounted thereon in a mixed manner. To the other heat generating members, efficiently radiate the heat generated from the other small heat generating members, and maintain the heat generating member temperature at a predetermined temperature, while maintaining a small temperature (low height) The object of the present invention is to provide a heat sink for forced cooling capable of sufficiently cooling a heat generating member and a cooling structure using the heat sink.

[0009]

In order to achieve the above object, according to the present invention, a small, low-height heat-generating member disposed downstream of a large heat-generating member or a heat sink mounted on the heat-generating member is provided. Generates a flat or curved guide plate that arbitrarily changes the flow direction of the cooling air that flows between the fins on the downstream side of the heat sink installed on the large heat generating member so that sufficient cooling air flows in. It was provided so as to have an inclination on the surface of the wiring board on which the members were arranged.

Further, for the small heat generating member disposed downstream of the large heat generating member, the fin portion of the heat sink installed on the large heat generating member is extended to the upper portion of the small (low height) heat generating member, and the fin is extended. A flat or curved guide plate for changing the flow direction is provided on the downstream surface so that the cooling medium collides with the small heat generating member. Further, the guide plate can be freely positioned at an inclination angle and an installation height according to a mounting pattern of the heat generating member and a flow rate of the cooling medium.

In a jet type cooling structure in which a cooling medium is blown in a direction perpendicular to the wiring board, after the cooling air collides with the target heat generating member, the air flows between the fins in parallel with the wiring board. . Therefore, the same guide plate as described above is provided on the two cooling air outflow surfaces so as to arbitrarily change the flow direction of the cooling air flowing out between the fins.

[0012]

1A and 1B are a perspective view and a sectional view, respectively, of a first embodiment of a cooling structure using a heat sink for forced cooling according to the present invention. On a wiring board 50 used for an electronic device or the like, a large heat generating member such as a multi-chip module 30 which generates high heat and a small heat generating member such as a semiconductor element 40 are mounted in the direction of flow of a cooling medium such as air. As for the heat generating members, the multi-chip module 30 is mounted on the upstream side of the flow, and the forced air cooling heat sink 20 of the present invention is provided on the surface of the multi-chip module 30.
Is installed. The heat sink is made of a material having high thermal conductivity, such as aluminum or copper, and a plurality of parallel plane plates are stacked on a single metal plane plate at intervals of about 1 to 3 mm.
The guide plate 10 is attached to the downstream side surface. Therefore, the heat sink is relatively easy and inexpensive to manufacture, and has a large heat radiation area.

The air blowing means of the present embodiment has a structure (parallel flow cooling structure) which blows air to the heat generating members 30 and 40 by a fan or a blower, which is the most common and widely used cooling method. The cooling air 1 is blown in a direction parallel to the wiring board 50, cools the two heating members arranged in the flow direction, and is discharged as warm air 2 in the same direction. The guide plate 10 made of, for example, the same material as the heat sink is attached to the heat sink 20 on the multi-chip module 30 with a downward inclination with respect to the wiring board 50. The mounting portion has a structure to be fitted into the fin, and both of them are bonded by, for example, a heat conductive adhesive. Here, the material of the guide plate 10 may not be the same as the material of the heat sink.

In the cooling structure of this embodiment, first, the wiring substrate 5
The cooling air 1 flowing along 0 flows into the inter-fin flow path of the heat sink 20. The cooling air 1 is supplied to the wiring board 5 by the guide plate 10 joined to the downstream side of the heat sink 20.
The air flow direction is controlled so as to go to the zero side, and the semiconductor element 40 installed downstream of the multi-chip module 30
It has a structure in which a lot of cooling air flows. And
The air flows in the same direction as the cooling air 1 and is discharged as warm air 2. In the heat sink 20 installed in the multi-chip module 30, heat generated from the multi-chip module is transmitted to the metal plate at the base of the fin, the fin, and the air, and is radiated. In the fin portion, heat exchange with air is best performed at the fin inlet end, and the amount of heat exchanged decreases as the wind temperature increases toward the downstream side of the inter-fin flow path. In this embodiment, since the heat guide area provided on the downstream side has the effect of expanding the heat transfer area, a relatively large amount of heat exchange can be ensured even at the downstream side of the fin. For this reason, the temperature distribution in the flow direction in the heat sink 20 is reduced, and the multi-chip module 30 can be cooled uniformly.

On the other hand, with respect to the semiconductor element 40 hidden on the downstream side of the multi-chip module 30, the cooling plate 1 is provided by the guide plate 10 as compared with the conventional heat sink (FIG. 11).
Flows in large quantities near the semiconductor element 40. Therefore, the vortex formed downstream of the semiconductor element 30 is reduced, and the circulation area of the cooling air is reduced. As a result, the cooling air flowing at a relatively low temperature and flowing quickly contacts the surface of the semiconductor element 40 and conducts heat with a high heat transfer rate on the surface. it can.

Here, a comparison will be made with the cooling structure using a conventional heat sink (FIG. 11). When the heat sink 20 of the present invention is changed to the parallel plate heat sink of FIG. 11A in FIG. 1, the cooling air 1 enters between the fins as in the case of the heat sink 20, but escapes substantially linearly downstream.
The semiconductor element 40 is not cooled. In the heat sink of FIG. 11B, the flow rate between the fins is increased by the flat plate on the fins, and the heat generating member 30 can be cooled well. However, it cannot contribute to the cooling of the semiconductor element 40 downstream. Therefore, when these heat sinks are used, the heat generating member 40
It is necessary to install a heat sink also on the upper side, and it can be seen that this embodiment can simply cool the heat generating member 40.

That is, in the present embodiment, by using the heat sink 20 of the present invention on the multi-chip module 30, it is not necessary to provide a heat sink on the semiconductor element 40 having a low heat generation density located downstream of the multi-chip module 30. By providing the guide plate 10 attached to the heat sink 20 at an inclination, air sufficient for cooling can be guided also to the semiconductor element 40, so that unnecessary cooling means can be eliminated more than necessary. Here, in the embodiment shown in FIG. 1, the semiconductor element 40 is not mounted with a heat sink, but if a heat sink is mounted, more excellent cooling is performed.

FIGS. 2A and 2B show another embodiment using the heat sink for forced cooling of the present invention. Wiring board 5
Heating members 30 and 40 are mounted on the wiring board 0, and the cooling air 1 is blown in a direction substantially parallel to the wiring board 50. The mounting structure of the heat generating member is the same as that of FIG. 1, and a large heat generating member, for example, a small semiconductor element 40 is mounted downstream of the multichip module 30 in the flow direction. There is a heat sink 29 of the present invention in thermal contact with the multi-chip module 30 and a flat fin-type heat sink 41 on the semiconductor element 40. The guide plate 18 is attached to a downstream side surface of the heat sink 29. The guide plate 19 extends from the base of the fin to the wiring board 50 side, and has a shape covering the circulation area. For this reason, the cooling air 3 that has flowed out between the fins smoothly enters the heat sink 41, so that the semiconductor element 40 is cooled and a function of reducing the circulation area is activated, thereby enabling effective heat exchange. Also, this heat sink 2
In No. 9, since there is almost no increase in pressure due to the guide plate 19, cooling with small pressure loss and high thermal efficiency can be performed.

FIGS. 3A and 3B show another embodiment using the heat sink for forced cooling of the present invention. Wiring board 5
Mounting of the heating members 30 and 40 on the cooling air 0 and the cooling air 1 thereof
1 is the same as that shown in FIG. 1, and another semiconductor element 40 is mounted downstream of the multi-chip module 30 in the flow direction. Multi-chip module 3
There is a heat sink 21 of the present invention in thermal contact with the heat sink 21. The fin portion of the heat sink 21 protrudes largely downstream (in the flow direction), and a part or the whole of the fin has a shape covering the rear semiconductor element 40. A guide plate 10 for controlling the flow direction of the cooling air flowing between the fins is provided on the downstream side surface (fin portion protruding in the flow direction) of the heat sink 21 as in FIG. The cooling air 1 entering from the front surface of the heat sink 21 (upstream of the flow) is accelerated by the area reduction when entering the fin, and flows.
It hits the guide plate 10 in the fin portion protruding downstream.
The guide plate 10 changes the direction of the cooling air flowing between the fins and causes the cooling air to collide with the surface of the semiconductor element 40. Therefore, the surface of the semiconductor element 40 collides with air perpendicular to the surface, so that the surface heat transfer coefficient is improved as compared with the case where cooling air is flown in parallel. As described above, the heat sink 21 of the present invention provided with the guide plate facilitates the flow of the cooling air from the front of the heat sink to the other semiconductor elements 40, thereby efficiently cooling not only the multi-chip module 30 but also the semiconductor elements 40. it can.

FIGS. 4A and 4B show another embodiment using the heat sink for forced cooling of the present invention. Another heat sink is mounted on another semiconductor element 40 mounted on the downstream side of the large multi-chip module 30 as in the case shown in FIG.
For example, the heat sink 41 of FIG. 11A is mounted in thermal contact. The heat sink 22 is mounted on the semiconductor element 30, and the fin protrudes downstream.
A guide plate is provided on the downstream side of the heat sink so as to be substantially perpendicular to the wiring board, and changes the horizontal flow between the fins to a right angle. The flow of the cooling air at this time is almost the same as in the second embodiment. The cooling air whose flow direction has been changed at right angles to the wiring board 50 by the guide plate 11 enters the heat sink 41 on the semiconductor element 40 from the upper surface side, splits vertically with respect to the main flow directions 1 and 2, and exits between the fins ( Some flow in the heat sink is opposite to the overall flow direction). Since the air flowing backward flows from the semiconductor element 40 toward the multi-chip module 30, the circulating flow formed on the rear surface of the semiconductor element 30 which is normally formed is expelled to the side. Therefore, the circulation area formed on the downstream side of the multi-chip module 30 where heat easily accumulates is reduced, and heat on the wiring board 50 can be efficiently discharged. In this embodiment, the example in which the guide plate 11 is installed substantially perpendicular to the substrate has been described, but the guide plate 11 may be installed to be inclined with respect to the substrate.

FIGS. 5A and 5B show an embodiment of a cooling structure by a parallel flow system in which cooling air 1 is blown in a horizontal direction to a wiring board 50 on which semiconductor elements are arranged. In this embodiment,
The flow direction can be changed smoothly by making the guide plate 12 installed on the downstream side of the heat sink 23 on the multi-chip module 30 smooth, and the heat-generating member on the wiring board 50 can be efficiently reduced by the same cooling effect as described above. Can cool well. In particular, with the configuration of the present embodiment, the flow direction can be changed smoothly, so that the ventilation resistance can be reduced and the noise can be reduced.

FIG. 6 shows a wiring board 5 on which semiconductor elements are installed.
This is an embodiment of a cooling structure by a jet system in which cooling air 1 is blown from a direction perpendicular to 0. In the cooling by the jet flow method, the cooling air 1 enters from the upper surface side of the heat sink by the nozzle 55 and is discharged from the heat sink in two directions. Also in this case, by installing the guide plate 11 that changes the flow direction at the two cooling air outlets in the heat sink, efficient cooling can be performed regardless of the installation position of the other adjacent semiconductor element 40.

FIGS. 7 and 8 show another embodiment. 7 and 8 show a cooling structure similar to that of FIG. 3, in which the cooling air 1 flows parallel to the wiring board and flows into the heat sinks 25 and 26. In FIG. 7, since the plate 13 installed on the downstream side of the heat sink can be rotated about the pin 14 serving as an axis, the guide plate can be adjusted to an angle at which air can be blown most efficiently regardless of the installation position of the semiconductor element 40. . Also, as shown in FIG.
And a structure in which the position of the guide plate 13 is changed up and down, the cooling performance can be arbitrarily controlled by adjusting the position of the guide plate 13 irrespective of the position of the other heat generating members.

FIGS. 9 and 10 show another embodiment. FIGS. 9 and 10 show a case where a plurality of the embodiments of FIGS. 1 and 3 to 8 are mixed in an electronic device.
The mounting form inside the electronic device housing is, for example, a stack of a plurality of wiring boards 50, each of which has a card row 58 on which a large number of memories 59 are installed and a multi-chip module 3.
Heating members such as zeros and semiconductor elements 40 are alternately arranged in several rows. Here, the blowing method is a parallel flow method (FIG. 9).
The cooling air 1 is sent to the heat-generating member on the wiring board 50 by a jet flow method (FIG. 10). 9 and 10, the heat sink 27 of the present invention in which the guide plate 11 is provided on the heat sink mounted on the multi-chip module is used.
Sufficient cooling air can be blown to the small (low height) semiconductor element 40 located downstream of the multi-chip module 30, and all the heat-generating members mounted on the wiring board 50 can be easily heated to a predetermined temperature. Can be cooled. Further, in the jet cooling structure shown in FIG. 10, the cooling air can be blown to the heat-generating members installed on all surfaces of the wiring board 50 by installing the heat sinks at different angles every 90 degrees. .

[0025]

According to the present invention, for a cooling structure of a high-density mounting system in which various heat generating members of various sizes are mixed, an appropriate amount of cooling air is applied to a heat sink or a heat generating member installed on each heat generating member. On the other hand, sufficient cooling air is blown to large and small heat-generating members mounted close to each other, so that heat generated from each heat-generating member is efficiently radiated and each heat-generating member temperature is maintained at a predetermined temperature. Can be.

[Brief description of the drawings]

FIG. 1 is an explanatory diagram of a first embodiment of the present invention.

FIG. 2 is an explanatory view of a second embodiment of the present invention.

FIG. 3 is an explanatory view of a third embodiment of the present invention.

FIG. 4 is an explanatory view of a fourth embodiment of the present invention.

FIG. 5 is an explanatory diagram of a fifth embodiment of the present invention.

FIG. 6 is an explanatory view of a sixth embodiment of the present invention.

FIG. 7 is a perspective view of a seventh embodiment of the present invention.

FIG. 8 is a perspective view of an eighth embodiment of the present invention.

FIG. 9 is a perspective view of a ninth embodiment of the present invention.

FIG. 10 is a perspective view of a tenth embodiment of the present invention.

FIG. 11 is a perspective view of a conventional heat sink for forced cooling.

[Explanation of symbols]

DESCRIPTION OF SYMBOLS 1 ... Cooling air, 10 ... Guide plate, 30 ... Multichip module, 40 ... Semiconductor element, 50 ... Wiring board, 55 ... Nozzle, 58 ... Memory card.

 ──────────────────────────────────────────────────続 き Continuing on the front page (72) Inventor Takayuki Shin 1st Horiyamashita, Hadano-shi, Kanagawa, General-purpose Computer Division, Hitachi, Ltd.

Claims (7)

[Claims] 1. A plurality of fins standing substantially in parallel on a metal flat plate in contact with a semiconductor element surface, and a cooling medium is blown in a direction substantially parallel or perpendicular to the metal flat plate. In the heat sink for forced cooling
A heat sink for forced cooling, wherein a plate for guiding a flow to another semiconductor element located downstream of the semiconductor element is provided at a part of an outlet of the cooling medium of the heat sink. 2. A heat sink for forced cooling according to claim 1, wherein said fins protrude from said flat metal plate in at least one flow direction. 3. A heat sink for forced cooling according to claim 2, wherein said fins protruding at least in one flow direction from said metal flat plate with said heat sink protrude above another heat generating member having a low height in the flow direction. . 4. The heat sink for forced cooling according to claim 1, wherein the flow guiding plate provided at a part of the cooling medium outlet of the heat sink is a curved plate. 5. A flat plate or a curved plate for guiding a flow, which is provided at a part of the cooling medium outlet of the heat sink, is inclined with respect to the metal flat plate. Heat sink for forced cooling installed on fins. 6. The cooling plate according to claim 1, 2 or 3, wherein the flow guide plate provided at a part of the cooling medium outlet of the heat sink has an inclination angle of the guide plate with respect to the flat metal plate. A heat sink for forced cooling provided with means that can be arbitrarily changed. 7. The heat guide plate according to claim 1, wherein the flow guide plate provided at a part of the cooling medium outlet of the heat sink is higher than the metal flat plate by a height of the guide plate. A heat sink for forced cooling provided with means for changing the position arbitrarily.