JPH1098139A - Forcedly air cooled structure and electronic equipment thereof - Google Patents

Abstract

PROBLEM TO BE SOLVED: To hold all heat generative members at a specified temp. by cooling heat generating members having high heat-generating densities by a jet flow structure which utilizes a gas flow mixed with a gas flow approximately along a substrate and crosses it with a flow along the fin surface of a heat sink. SOLUTION: A multiple-chip module 30 has a high heat-generating density and hence needs a jet flow cooling structure to cool the individual members. It jets air 4 from both side fins, approximately perpendicularly to a gas flowing direction, while a cooling air 1 blown approximately parallel to a substrate is accelerated in a restricted passage at the module 30 being cooled with the jet flow. At a heat sink the air flow cooled with the jet flow is jetted, approximately perpendicularly to the gas flow approximately in parallel with the substrate, and hence both air flows are mixed to send the cooled air enough to small electronic elements 40 round the module so that electronic elements 45, 46 mounted on the heat sink 20 are well cooled with the low temp. air.

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a cooling structure for an electronic device having a heat generating member such as an electronic device, and more particularly to a cooling structure for an electronic device disposed on one or more substrates stacked in a housing of the electronic device. The present invention relates to a forced air cooling structure that efficiently cools a plurality of heat-generating members mounted on a high-density and complicated structure.

[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, and cost reduction.
In addition, the number of mounted devices tends to increase. 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 the signal propagation delay time, a mounting form of a multi-chip module in which a large number of chips are mounted on a substrate such as a ceramic and cooled collectively is used for the electronic 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.

[0003] Each heat generating member must be maintained at a rated temperature or lower so as not to damage or malfunction the element due to an excessive temperature rise. For this reason, in cooling electronic devices, there are many structures using a heat sink for increasing the heat radiation area and improving the cooling performance. In particular, various forced air cooling heat sinks are installed on the surface of an electronic element that generates a large amount of heat depending on the heat generation density and the specified temperature. The heat sink is made of a material having high thermal conductivity, for example, aluminum or copper. Generally, a flat fin type heat sink (FIG. 11) in which a plurality of parallel flat plates are arranged on a single metal flat plate at intervals of about 1 to 3 mm. (a)) and a pin fin-type heat sink (FIG. 11B) in which a large number of prisms or cylinders are arranged on a metal flat plate are often used. The flat fin-type heat sink has the advantages that it is relatively easy and inexpensive to manufacture, has a large heat dissipation area, and has a small pressure loss. Further, the pin fin type heat sink has an advantage of being non-directional with respect to the flow, and is used according to the purpose.

In the forced air cooling structure, cooling air is sent to each heat generating member mainly using a fan or a blower. There are two types of cooling systems: a parallel-flow cooling structure that blows air from the substrate in a substantially horizontal direction, and a jet-flow cooling structure that blows air from the substrate in a substantially vertical direction. A jet type cooling structure having a large heat exchange capacity is used.

In recent electronic devices, in addition to increasing the heat generation density, electronic elements having different sizes inside the housing tend to be arranged in the flow direction of the cooling air. For this reason, when air-cooling an electronic element mounted at a high density, there is a problem in that a small, high-height heating element such as a multi-chip module is disposed adjacent to a large and high heat generating member. Low cooling performance of the electronic element is deteriorated. big,
Cooling air is less likely to enter the downstream of the high heat generating member, and a region with a low flow velocity and a high wind temperature is formed in a wide area near the substrate. If a small, low-height heat-generating member is arranged in this area, its cooling performance will deteriorate significantly.

As described above, since the tendency of high-density mounting is progressing, it is not enough to install a heat sink shown in FIGS. 11A and 11B on a heat-generating member that generates high heat and simply blow cooling air. Insufficient cooling of all electronic elements on the substrate. In addition, jet cooling with a large amount of exchanged heat is effective for cooling a multichip module having a high heat generation density. Therefore, a method utilizing this cooling structure is required. However, in the conventional jet cooling structure example (Japanese Patent Laid-Open Publication No. Hei 5-2914747), as shown in FIG. 11C, the heat is intensively collided with a heat sink provided on a heat generating member, and only the heat generating member is cooled. Met. The structure focuses on a method of discharging warm air from a heat sink staying on a substrate, and in FIG. 11C, discharge is performed using an air flow parallel to the substrate. . In addition, JP-A-6-112382, JP-A-6-112383, and JP-A-6-112383
All of the jet cooling structures disclosed in JP-A-1220387 and the like are structures for centrally cooling only a heat-generating member to be cooled.

[0007]

In the conventional example of the structure of jet cooling, a multi-chip module having a high heat generation density is a structure for individual cooling when it is regularly arranged on one substrate. In many cases, cooling of a mounting system in which heat generating members of various sizes are irregularly arranged on one substrate is not considered. In other words, in a structure in which only heat generating members having a high heat generation density are jet-cooled on a board mounted with high density, sufficient cooling air is not blown to other small heat generating members mounted on the same board, resulting in malfunction or the like. It is easy to cause trouble. Therefore, a means for guiding sufficient cooling air is required for those electronic elements. Here, the complexity of the air guiding structure and the shape of the heat sink affects the increase in pressure loss, so that sufficient consideration is required in cooling design.

SUMMARY OF THE INVENTION An object of the present invention is to provide a forced air cooling structure for electronic equipment mounted at high density, by simultaneously introducing a parallel flow type and a jet type air blowing structure to various heat generating members on one substrate, thereby achieving a pressure loss. An object of the present invention is to provide a forced air cooling structure capable of keeping all the heat generating member temperatures at a predetermined temperature without greatly increasing the temperature.

[0009]

In order to achieve the above object, according to the present invention, a large heat generating member having a high heat generation density is cooled by a jet structure, and other heat generating members having a low height are provided on a substrate. The airflow generated by the airflow and the jet flow flowing along the outline is cooled using the mixed airflow. At this time, the height of the jet part of the jet is set to be 1.4 times or less the sum of the height of the heat-generating member for individually cooling and the height of the heat sink, and the fin surface of the heat sink installed on the heat-generating member intersects the flow. With this structure, a high flow velocity region of the airflow along the substrate is formed near the substrate. Further, since a baffle plate in which the high flow velocity region of the airflow along the substrate is formed near the substrate is provided upstream of the airflow substantially along the substrate, a main flow region of the airflow is formed near the substrate.

A heat sink provided on the heat-generating member for individual cooling and a plate for controlling airflow are provided around the heat-generating member, so that warm air used for individual cooling flows through the upper part of the airflow channel.

[0011]

1 and 2 show a perspective view and a sectional view of a first embodiment of a forced air cooling structure according to the present invention. The inside of the housing of the electronic device has a mounting form in which a plurality of substrates are stacked. Each of the substrates 50 includes a card array 95 on which a large number of memories 90 are mounted and a multi-chip module 30.
And other electronic elements 40 are alternately mounted in several rows. These multi-chip modules 3 mounted on a substrate
0 and the electronic element 40 are mounted irregularly in the airflow direction 3 of the cooling air. In the multi-chip module 30 having a high heat generation density, the flat fin type heat sink 20 is installed so that the fin surface substantially intersects the air flow direction.
A jet nozzle 80 is provided on the upper part thereof, and the air blown from the air duct 85 directly collides with the heat sink base surface.

The flat fin type heat sink 20 is made of a material having high thermal conductivity, for example, aluminum or copper, and is formed by stacking a plurality of parallel flat plates on a single metal flat plate at an interval of about 1 to 3 mm. . Therefore, there is an advantage that manufacture is easy and a large heat radiation area can be obtained. In addition, since it has directivity with respect to the flow, the air flowing between the fins can be discharged in a predetermined direction.

The blowing means blows a part of the cooling air blown by a fan, a blower or the like to the multi-chip module 30 which generates a large amount of heat through the air duct 85, and blows other cooling air substantially parallel to the substrate. It is. Moreover, each may be an individual blowing system. The airflow at this time will be described.
Because of the high heat generation density, individual cooling is required by a jet cooling structure. Therefore, the air 4 subjected to heat exchange therefrom flows out of the fin portions on both sides in a direction substantially perpendicular to the airflow direction. On the other hand, the flow of the cooling air flow 1 blown substantially parallel to the substrate is reduced and accelerated in the multi-chip module portion to be jet-cooled. Furthermore, in the heat sink portion, since the airflow jet-cooled against the airflow substantially parallel to the substrate is ejected at a substantially right angle, the two airflows are mixed to form a high-speed flow region near the substrate, and the module is formed. You will pass through the side. Therefore, sufficient cooling air mixed with the small electronic elements 40 around the module is sent to the electronic elements 40 and the electronic elements 45 and 46 provided with the conventional heat sinks of FIGS. 11 (a) and 11 (b). Low-temperature air blowing is possible. In each electronic element, the heat transfer coefficient on the surface and the fin surface is increased, so that the electronic element temperature can be cooled to a predetermined temperature.

FIG. 9 shows the flow velocity distribution of the cooling air by the combination of the parallel flow and the jet shown in the present embodiment. Heating member (height Hd / 2) mounted in a rectangular section duct (height Hd, width Wd) and fins (height Hd) on its surface
/ 2). The flow of the cooling air into the duct is a cross section of the inflow area B or a cross section of the inflow area B or C that differs depending on the installation direction of the heat sink. In the cooling structure of the present embodiment (in the case of the inflow regions A and B), it can be seen that the high flow velocity region continues near the substrate to the rear of the airflow. The air flowing from A mixes with the flow of B orthogonal to A and flows toward the substrate. Therefore, the high-speed region formed near the substrate remains downstream even after passing through the narrow side surface of the heat-generating member. On the other hand, it can be seen that only by jet cooling (in the case of the inflow area B), the airflow is rapidly diffused behind the heating member. With the jet flow alone, the airflow that has flowed out of the heat sink is less likely to flow downstream, so that the flow velocity component that diffuses upward in the duct becomes stronger. Therefore, it is difficult to cool a small downstream electronic element mounted on the substrate. In addition, when the installation direction of the heat sink is changed by 90 degrees with respect to the present embodiment (in the case of the inflow areas A and C), it can be seen that the main flow of the air current is biased toward the corner of the duct. Also in this case, it is unsuitable for cooling a small electronic element in the vicinity near the center of the duct.

FIG. 3 is a sectional view of a second embodiment of the forced air cooling structure according to the present invention. This is a mounting form similar to FIG. 2, in which the multi-chip module 30 and the electronic elements 40 are irregularly arranged on the substrate 50 in the airflow direction. The heat-generating members having a high heat-generating density on the substrate are individually supplied from the air duct 85 to the cooling air 5.
Is blown, and the air 2 flows into the heat sink 20 provided on the heat generating member 30 from the direction substantially perpendicular to the substrate 50 via the jet nozzle 80. The air flow 4 heat-exchanged in the heat sink 20 installed so as to intersect with the air flow substantially parallel to the substrate 50 is divided into two directions, flows out between the fins, and is mixed with the air flow and discharged. On the other hand, small air 1 for cooling the electronic element is blown in a direction substantially parallel to the substrate 50. The flow of the parallel air flow 1 is suppressed in the individual cooling section, and the high flow velocity region is maintained near the substrate.
Is provided on the upstream side of the parallel flow, a high flow velocity region of the parallel flow upstream of the substrate can be maintained on the substrate side. For this reason, the high flow velocity region after the individual cooling unit can be further brought closer to the substrate side, so that a large amount of cooling air can be sent to the small electronic elements 40 on the substrate. Therefore, heat transfer on the electronic element surface increases, and the cooling effect can be enhanced.

FIG. 4 shows a third embodiment of the forced air cooling structure of the present invention. 2 and FIG. 3 in which the multi-chip module 30 and the electronic elements 40 are irregularly arranged on the substrate 50 in the airflow direction. In this embodiment, a flat plate 77 having substantially the same height as the space above the heat sink 20 is provided at the jet nozzle 80. Since the amount of air passing above the heat sink 20 due to the height of the jet nozzle becomes substantially zero and the flow velocity near the substrate increases, cooling of the small electronic element 40 can be promoted. FIG. 10 shows the structure of the inflow areas A and C in FIG.
In the case where only the duct height Hd was increased, the flow velocity was described with respect to the ratio of Hd to the increased duct height Hd *. The flow velocity is 0.2 Wd, 0.4 in the y direction at a position Z = 3 mm near the substrate.
Two locations of Wd are shown. Here, the vertical axis in FIG. FIG. 10 shows that when the flow velocity near the substrate is 1.4 times or more the duct height, the flow velocity ratio of the airflow flowing near the substrate decreases to 1 or less. Therefore, by setting the height of the jet duct 80 to be 1.4 times or less the sum of the heights of the heat generating member 30 and the heat sink 20,
An air flow sufficient for cooling can be sent to a small electronic element when mounted at high density.

FIG. 5 is a perspective view of another embodiment of the forced air cooling structure of the present invention. FIG. 1 shows a card array on which a large number of memories 90 are mounted, and a board 50 on which 95 multi-chip modules 30 and electronic elements 40 are arranged irregularly in the airflow direction.
This is a mounting form similar to. The multi-chip module 30 that generates high heat is cooled individually from the cooling air 2 by a jet flow method, and the air flow 1 parallel to the substrate 50 is used for cooling other electronic elements.
To blow. In this embodiment, the guide plate 73 is provided at the air outlet of the individual cooling unit, and the guide plate 72 is provided on another substrate. The guide plate 73 has substantially the same height as the heat-generating member 30, and the installation portion with the substrate is supported by a flat plate. The guide plates 72 are similarly installed on the substrate, and these guide plates constitute an airflow channel near the substrate. By installing the guide plate and the flat plate at the installation part of the board at an angle to the flow direction, sufficient air can be sent to a position where cooling air does not easily enter, so that all electronic elements can be cooled even in high-density mounting . Here, the guide plate may be inclined with respect to the substrate. Further, if the installation portion with the substrate is not a flat plate but a curved plate, the flow direction can be smoothly changed.

FIG. 6 is a perspective view of a fifth embodiment of the forced air cooling structure according to the present invention. This is a mounting form in which a card row on which a large number of memories 90 are mounted, a board 50 on which a multi-chip module 30 and electronic elements 40 are randomly arranged in the airflow direction are arranged, and a guide plate 75 is formed on the entire surface of the board. . The guide plate 75 is provided with a through-hole in the individual cooling unit, and the heat sink 20 installed in the multi-chip module 30 projects upward. For this reason, the flows of the air flow 2 and the parallel flow 1 by the individual cooling are roughly separated. In addition, since the guide plate 75 is a support portion 79 formed by bending several notches on the plate surface toward the substrate, the flow near the substrate is guided to the entire substrate by the notch shape and the notch angle, and all heat is generated. The component can be cooled. Further, as shown in FIG. 7, the flat plate 76 can be easily manufactured by pressing from one side.

FIGS. 8A and 8B show an embodiment relating to the structure of the heat sink for individual cooling in the forced air cooling structure of the present invention. In the heat sink 21 of (a), the base portion is extended, and an inclination θ is provided with respect to the base surface. Therefore, the cooling air 2 flows between the fins via the jet duct 80, exchanges heat with the heat sink, and flows out. At this time, since the air flows in the direction opposite to the base surface due to the inclination of the outflow portion, the cooling air by the parallel flow easily enters the substrate side. Therefore, the temperature of the mixed gas flow near the substrate can be reduced. Similarly, in the heat sink 22 of (b), the fin surface of the heat sink is inclined to direct the relatively low-temperature air flow on the upstream side to the substrate side, so that the temperature of the mixed air flow can be lowered. Therefore, by using these heat sinks, the cooling effect of electronic elements other than the heat-generating member to be jet-cooled can be promoted.

[0020]

According to the present invention, in a cooling structure of a high-density mounting system in which various heat-generating members of various sizes are arranged in a complicated manner, while the heat-generating members having a high heat-generating density are individually cooled, other cooling is not performed. Sufficient cooling air is also sent to the heat generating members, so the heat generated from each heat generating member is efficiently radiated,
Each heating member temperature can be maintained at a predetermined temperature.

[Brief description of the drawings]

FIG. 1 is a perspective view of a first embodiment of the present invention.

FIG. 2 is a sectional view of a first embodiment of the present invention.

FIG. 3 is a sectional view of a second embodiment of the present invention.

FIG. 4 is a sectional view of a third embodiment of the present invention.

FIG. 5 is a perspective view of a fourth embodiment of the present invention.

FIG. 6 is a perspective view of a fifth embodiment of the present invention.

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

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

FIG. 9 is an explanatory diagram of a calculation result representing a flow velocity distribution according to the present invention.

FIG. 10 is an explanatory diagram of a calculation result representing a change in flow velocity according to the present invention.

FIG. 11 is an explanatory view of a conventional example.

[Explanation of symbols]

1, 2, cooling air, 20, heat sink, 30, multi-chip module, 40, electronic element, 50, substrate, 70
... guide plate, 80 ... jet nozzle, 85 ... air duct, 90
... memory, 95 ... card row.

 ──────────────────────────────────────────────────続 き Continuing from the front page (72) Inventor Takahiro Oguro 1st Horiyamashita, Hadano-shi, Kanagawa Prefecture Nichi Works, Ltd. General-purpose Computer Business Division (72) Inventor Takayuki Shin 1st Horiyamashita, Hadano-shi, Kanagawa 1st Hitachi, Ltd. General Computer Division of Manufacturing

Claims (12)

[Claims] 1. A cooling air is blown to a heat generating member on a substrate on which a plurality of heat generating members are mounted in a flow direction of the cooling air. In the forced air-cooling structure of electronic equipment in which a heat sink in which a plurality of other metal plates are vertically arranged on a flat metal plate is installed on a heat generating member that individually sends cooling air to a part of A forced air cooling structure, wherein a metal flat plate of the heat sink provided on the heat-generating member to be cooled is installed so as to intersect with an air flow direction flowing substantially along a substrate. 2. A forced air cooling structure according to claim 1, wherein a flow guide member is provided at the bottom of the fin on the cooling air upstream side of the heat sink provided on the heat-generating member to be individually cooled. . 3. A forced air cooling structure according to claim 1, wherein the heat sink base metal plate provided on the heat-generating member to be individually cooled is projected with an inclination in the longitudinal direction of the fin. 4. A forced air cooling structure according to claim 1, wherein at least one plate having substantially the same height as the heat-generating member to be individually cooled is installed on the substrate on which the heat-generating member is mounted. 5. A flat plate according to claim 4, wherein a supporting portion of the plate, which is provided on the substrate surface at substantially the same height as the heat-generating member to be individually cooled, is inclined with respect to the flow direction on the substrate. Forced air cooling structure, which is a flat or curved plate. 6. A forced air cooling structure according to claim 4, wherein a plate provided on the surface of the substrate at substantially the same height as the heat-generating member to be individually cooled is installed obliquely with respect to the substrate. 7. A forced air cooling structure according to claim 4, wherein at least one notch is provided on a surface of a plate provided on the substrate surface at substantially the same height as said heat-generating member to be individually cooled. . 8. A forced air cooling structure according to claim 7, wherein the notch is formed by local pressurization from one side. 9. A forced air cooling structure according to claim 1, wherein a flat plate or a curved plate having substantially the same height as an introduction portion for introducing cooling air is provided above a heat sink provided on the heat-generating member to be individually cooled. 10. A forced air cooling structure according to claim 9, wherein the plate provided above the heat sink has a slope with respect to an air flow substantially parallel to the substrate. 11. The cooling structure according to claim 1, wherein a height of a duct portion for introducing cooling air to a heat sink provided on the heat-generating member to be individually cooled is equal to the height of the heat-generating member and the heat sink. Forced air cooling structure that is less than 1.4 times the sum of heights. 12. An electronic device comprising a heating member mounted on at least one of a single or a plurality of wiring boards, and a blower means provided thereon, and the forced cooling structure according to any one of claims 1 to 11 provided alone or in plurality.