Electronic device and complex electronic device

DIMMs to be cooled are mounted in DIMM areas of a printed circuit board of a system board. An air intake port that introduces cooling air is arranged on a side plate of the system board, whereas an air discharge port that discharges the cooling air is arranged on another side plate. The cooling air flows in a direction that is oblique with respect to the side plate. The air intake port is arranged at a position that is offset in the direction in which the cooling air is supplied. Accordingly, cooling is possible by efficiently bringing the cooling air into contact with the DIMMs.

FIELD

The embodiments discussed herein are directed to an electronic device and a complex electronic device.

BACKGROUND

Components included in electronic devices include heat-generating components that generate heat. An increase in temperature of the electronic devices due to heat generated by the heat-generating components causes an operational abnormality in the electronic devices. Accordingly, a cooling mechanism is arranged in the conventional electronic devices. Cooling mechanisms of these electronic devices includes a liquid cooling method for circulating a liquid whose temperature is lower than that of the heat-generating components to be cooled and an air cooling method for cooling the components to be cooled by bringing cooling air into contact with them.

In the conventional air cooling method, in a casing (or a chassis) that includes a circuit boards having mounted thereon the heat-generating components, an opening is arranged at a position close to the heat-generating component and cooling air is introduced from the opening. This is because the components to be cooled are intensively cooled by locally introducing the cooling air in the vicinity of the components to be cooled.

In the conventional technology, it is assumed that the cooling air makes contact from the front with respect to the surface of the casing that includes a board having mounted thereon the heat-generating component, and thus an air intake opening is arranged at the center of the heat-generating component to be cooled.

Furthermore, the conventional technology also uses complex electronic devices in which a plurality of electronic devices are connected with each other and share the cooling air supplied to or discharged from each of the electronic devices.

However, the cooling air is not always supplied from the front with respect to the wall of the casing of the electronic device. With the conventional cooling structure that has an opening at the center of the electronic component, if the cooling air is supplied from a direction that is oblique with respect to the wall of the casing of the electronic device, the cooling air enters from the opening oblique with respect to the wall. If the cooling air enters obliquely from the opening, the cooling air effectively makes contact in the region on the downstream side of the heat-generating component to be cooled; however, the cooling air does not sufficiently make contact in the region on the upstream side. Accordingly, the cooling of the heat-generating component varies, thus reducing the cooling efficiency.

As described above, in the conventional technology, there is a problem in that the cooling efficiency is reduced when the cooling air is supplied from a direction that is oblique with respect to the wall of the casing of the electronic device.

SUMMARY

According to an aspect of an embodiment of the invention, an electronic device includes a circuit board having mounted thereon a component; a first side plate that includes an air intake port that introduces the cooling air over the circuit board; and a second side plate that includes an air discharge port that discharges the cooling air from the circuit board, wherein the first side plate includes the air intake port at a position shifted from a position closest to the component, and a direction in which the position of the air intake port is shifted corresponds to an angle of an intake stream of the cooling air with respect to the first side plate.

DESCRIPTION OF EMBODIMENTS

Preferred embodiments will be explained with reference to accompanying drawings. In the embodiments described below, a server device will be described as an example of the complex electronic device. The server device has a system board, as an electronic device, having mounted thereon at least an arithmetic processing unit and a storage device. The arithmetic processing unit mentioned here is represented by, for example, a central processing unit (CPU), a micro processing unit (MPU), or a micro control unit (MCU). The storage device mentioned here is represented by, for example, a semiconductor memory, such as a random access memory (RAM) or a read only memory (ROM).

Furthermore, the disclosed technology is not limited to the server device or the system board; however, it can be widely used for a complex electronic device that is configured by combining electronic devices each having mounted thereon heat-generating electronic components, such as an arithmetic processing unit, a storage device, a power supply device, or the like. For example, the disclosed technology can be used for a communication device represented by a switchboard or a router. Furthermore, the disclosed technology can also be used for a personal computer having mounted thereon a motherboard.

[a] First Embodiment

FIG. 1is a sectional view, in the horizontal direction, of a system board that is an electronic device according to a first embodiment. A system board201illustrated inFIG. 1includes, on a printed circuit board40, a dual inline memory module (DIMM) and a power supply board52. The DIMM is a type of RAM module in which a high integrated semiconductor memory elements are mounted on both sides of a rectangular-plate shaped circuit board and is arranged perpendicular to the printed circuit board40.

The DIMMs are heat-generating components to be cooled by cooling air and are arranged by being distributed in DIMM areas51-1to51-6. The system board201includes a first side plate41that includes an air intake port61for introducing cooling air over the printed circuit board40and a second side plate42that includes an air discharge port62for discharging the cooling air from the printed circuit board40. InFIG. 1, the power supply board52is arranged at the center portion of the printed circuit board40. The DIMM areas51-1to51-3are arranged on the side plate41side, and the DIMM areas51-4to51-6are arranged on the side plate42side. Then, the air intake port61is arranged in the vicinity of the DIMM area51-2and the air discharge port62is arranged in the vicinity of the DIMM area51-5.

The system board201is arranged oblique with respect to a casing (or a chassis) of a server100, i.e., the complex electronic device. The server100includes an air intake duct area DA1that supplies the cooling air to the air intake port61that is arranged on the side plate41of the system board201and an air discharge duct area DA3that discharges the cooling air discharged from the air discharge port62that is arranged on the side plate42of the system board201.

Furthermore, the server100also includes a cooling device113between the air discharge port62arranged on the side plate42and the air discharge duct area DA3. The cooling device113is typically a fan that generates the cooling air due to rotation. Furthermore, an intermediate duct area DA2is formed between the air discharge port62and the cooling device113.

The air intake duct area DA1supplies the cooling air at a predetermined angle that is greater than 0 degrees and less than 90 degrees with respect to the air intake port61. The system board201includes the air intake port61, on the side plate41, at the position shifted from the position closest to the DIMM area51-2to the air intake duct side.

As described above, for the cooling air that is introduced obliquely relative to the front of the printed circuit board40to be cooled, by offsetting the opening position of the air intake port61in the air flow direction instead of arranging it at the center of the electronic component group to be cooled, the cooling air uniformly makes contact with the electronic components and thus the cooling can be efficiently performed.

In the following, the server100will be described with reference toFIGS. 2A,2B,2C, and2D.FIG. 2Ais a perspective view, from the front, of the casing of the server100.FIG. 2Bis a perspective view, from the back, of the casing of the server100.FIG. 2Aillustrates the state in which a front surface plate that is an openable and closable door arranged on the front side of the server100is removed and the front surface plate is not illustrated. Furthermore, inFIG. 2B, a back surface plate is not illustrated.

As illustrated inFIGS. 2A and 2B, the server100includes a top plate101, a base plate102, a first side surface plate103, a second side surface plate104, a shelf108a, and a shelf108b.

The base plate102is arranged parallel to the arrangement surface of the server100. Furthermore, casters106that are used to move the server100and legs107that are used to fix the server100are arranged on the base plate102.

The first side surface plate103and the second side surface plate104are arranged perpendicular to the base plate102. The top plate101is arranged perpendicular to the first side surface plate103and the second side surface plate104, i.e., is arranged parallel to the base plate102.

The server100includes the front surface plate (not illustrated) and the back surface plate (not illustrated) that is arranged opposite the front surface plate. The front surface plate is an openable and closable door that is arranged to cover the rectangular opening, which is formed on the front surface of the server100and is formed by the top plate101, the base plate102, the first side surface plate103, and the second side surface plate104. The back surface plate is an openable and closable member that is arranged to cover the rectangular opening, which is formed on the back surface of the server100and is formed by the top plate101, the base plate102, the first side surface plate103, and the second side surface plate104.

As illustrated inFIG. 2A, the server100includes the shelf108aand the shelf108bin a space that is bounded by the first side surface plate103and the second side surface plate104. The system boards201are arranged on each of the shelf108aand the shelf108b.

The shelf108aincludes a guide panel109athat has the same number of combinations of guide rails that are arranged in parallel. Similarly, the shelf108bincludes a guide panel109bhas the same number of combinations of guide rails that are arranged in parallel.

The guide panel109aand the guide panel109bare arranged such that the positions of a bottom surface of the guide panel and a horizontal surface of each of the guide rails are the same and such that the guide rails are arranged perpendicular to the base plate102.

Then, in the server100, the shelf108aand the shelf108bare arranged such that the guide panel109aand the guide panel109bare arranged to have the angle of α° (0°<α<90°) with respect to the first side surface plate103in the horizontal direction. By arranging the system boards201on the plurality of guide rails that face each other, it is possible to arrange a plurality of system boards201on each of the shelf108aand the shelf108bin a layered manner.

Furthermore, on the front surface of the server100, an air intake duct opening is arranged in the space bounded by the shelf108aand the first side surface plate103. Similarly, on the front surface of the server100, an air intake duct opening is arranged in the space bounded by the shelf108band the first side surface plate103.

Furthermore, a power supply device110and a shelf111are arranged, in the vertical direction of the server100, between the shelf108aand the shelf108b. The power supply device110is arranged on the first side surface plate103side, whereas the shelf111is arranged on the second side surface plate104side.

The power supply device110controls the power supply supplied to the electronic device arranged in the server100in which electronic components are mounted on a plurality of printed circuit boards. An interface board that is used by an electronic device in order to transmit and receive data to/from an external unit is arranged on the shelf111.

The shelf111includes a guide panel112that has guide rails arranged in parallel. By arranging the interface boards on the guide rails arranged on the guide panel112, it is possible to arrange a plurality of interface boards on the shelf111in a layered manner.

As illustrated inFIG. 2B, the server100includes connecting circuit boards114referred to as a back plane are arranged on the back surfaces of the shelf108aand the shelf108b. Each of the connecting circuit boards114is arranged perpendicular to the guide panel109a. Furthermore, on the back surfaces of the shelf108aand the shelf108b, the connecting circuit boards114are arranged to cover the rectangular openings that are formed using the guide panel109.

Each of the connecting circuit boards114electrically connects the system boards201arranged on the shelf108aand the shelf108b. By connecting a plurality of connecting terminals arranged on the back surface of the plurality of system boards to each of the connecting circuit boards114, the system boards201are electrically connected.

Because the first side plate41of the system board201is arranged to have an angle of α° with respect to the first side surface plate103in the server100in the horizontal direction, each of the connecting circuit boards114is arranged to have an angle of 90°+α° with respect to the first side surface plate103in the horizontal direction.

On the back surface of the server100, an air discharge duct opening is arranged in the space bounded by the second side surface plate104and the guide panels109aand109b. In the server100, the cooling device113is arranged in the space formed between the second side surface plate104and the guide panels109aand109b. The cooling device113is formed by arranging, in the vertical and the horizontal directions, a plurality of fans having the same structure. The fans are typically axial fan. The cooling device113is arrange to have a second angle of β° (0°≦β≦90°) with respect to the first side surface plate103.

Furthermore, in the server100, a cooling device116and a connecting circuit board117are arranged side by side on the back surface of the shelf111. The cooling device116cools electronic components mounted on the plurality of interface boards that are arranged on the shelf111. The connecting circuit board117is a back plane that electrically connects a plurality of interface boards that are arranged on the shelf111. The power supply device110is arranged between the connecting circuit board117and the first side surface plate103.

FIG. 2Cis a perspective view, from the front, of the system board201mounted on the server100. As illustrated inFIG. 2C, the plurality of system boards201are arranged, on the shelf108a, in the space formed by the top plate101, the first side surface plate103, and the second side surface plate104. On the shelf108a, the system boards201are arranged such that the front surfaces of the system boards201are aligned in the same plane. The system boards201are arranged in the shelf108bin a similar manner to the shelf108a.

FIG. 2Dis a schematic diagram illustrating a state in which the top plate101is removed from the state illustrated inFIG. 2C. As illustrated inFIG. 2D, the system boards201arranged on the shelf108aare arranged such that the side plate41is arranged to have an angle with respect to the first side surface plate103in the horizontal direction and are electrically connected to each of the connecting circuit boards114. The space bounded by the first side surface plate103and the guide panel109aon the shelf108ais an air intake duct area DA1. An air intake duct opening is arranged in the air intake duct area DA1on the front surface of the server100.

The cooling device113illustrated inFIG. 2Dis arranged, in the space bounded by the shelf108aand the second side surface plate104, at an angle of β° with respect to the first side surface plate103in the horizontal direction. The space bounded by the shelf108a,the guide panel109aof the shelf108a, and the cooling device113is an intermediate duct area DA2.

Furthermore, the space bounded by the cooling device113and the second side surface plate104illustrated inFIG. 2Dis an air discharge duct area DA3. An air discharge duct opening is arranged in the air discharge duct area DA3on the back surface of the server100.

InFIG. 2D, by operating the cooling device113, the cooling air flowing from the air intake duct opening into the server100changes its flow direction, in the air intake duct area DA1, toward the system boards201. Then, the cooling air that has changed its flow direction toward the system boards201cools inside the system boards201and flows over the system boards201.

The cooling air flowing over the system board201changes its flow direction, in the intermediate duct area DA2, toward the cooling device113. Then, the cooling air that has changed its flow direction toward the cooling device113flows through the cooling device113and is discharged outside of the server100from the air discharge duct opening via the air discharge duct area DA3.

To simplify the explanation,FIG. 1illustrates a case in which the air intake port61is arranged near the DIMM area51-2and the air discharge port62is arranged near the DIMM area51-5. However, to improve the cooling efficiency, air intake ports associated with the DIMM areas51-1to51-3and air discharge ports associated with the DIMM areas51-4to51-6are preferably arranged.

FIG. 3is a perspective view of the system board201that includes air intake ports61-1to61-3associated with the DIMM areas51-1to51-3, respectively. As described above, the cooling air enters obliquely relative to the front of the side plate41of the system board201.

FIG. 4is a schematic diagram illustrating, in outline, the configuration of the system board201.FIG. 5is a top view of the system board201. Electronic components, such as an arithmetic element53, a communication element54, the power supply board52, and the like are mounted, by soldering, on the printed circuit board40on the system boards201. Furthermore, a connector44that is connected to the connecting circuit board114, that electrically connects to other printed circuit boards40, and that supplies the power supply is arranged on one end of the printed circuit board40. The side plates41and42, which are formed from a sheet metal, reinforce and protect the printed circuit board40and are fixed using a screw or the like.

In the first embodiment, a liquid cooling method is used to cool some of the electronic components. Water cooling jackets81that cool heat generated by some of the electronic components, i.e., the arithmetic element53and the communication element54in the examples illustrated inFIGS. 4 and 5, are arranged. Each of the water cooling jackets81is in close contact with each component and is typically a water cooling tube that allows a liquid refrigerant to flow between the water cooling jackets81. The water cooling jackets81are connected by water cooling tubes.

The side plate41on the air intake side includes the air intake port61-1associated with the DIMM area51-1, the air intake port61-2associated with the DIMM area51-2, and the air intake port61-3associated with the DIMM area51-3. These air intake ports61-1to61-3are arranged by offsetting from the front of the DIMM area, i.e., from the position closest to the DIMM area, to the front side of the system board201, i.e., from the upstream side of the cooling air stream.

The side plate42on the air discharge side includes an air discharge port62-1associated with the DIMM area51-4, an air discharge port62-2associated with the DIMM area51-5, and an air discharge port62-3associated with the DIMM area51-6. These air discharge ports62-1to62-3is arranged on the front of the DIMM area, i.e., at the position closest to the DIMM area, without being offset.

FIG. 5illustrates the differences of the positions of the air intake ports by comparing the system board201in which an air intake port is offset and a system board200in which an air intake port is arranged, without being offset, at the front of the DIMM area, i.e., at the position closest to the DIMM area.

When comparing, used as comparative example, the positions of air intake ports61-1ato61-3aon the system board200with the positions of the air intake ports61-1to61-3on the system board201, the air intake ports61-1to61-3are shifted to the front side of the system board201. Accordingly, when viewed from the front side of the side plate41, instead of being arranged at the front of the DIMM that corresponds to the heat-generating component to be cooled, the air intake ports61-1to61-3are shifted in the direction in which the cooling air is taken in; therefore, the air intake ports61-1to61-3are located at the offset position.

In the following, results of the thermal hydraulic analysis performed on the cooling air on the system board201will be described.FIG. 6is a schematic diagram illustrating the target portion for the thermal hydraulic analysis. The region surrounded by the broken line illustrated inFIG. 6is assumed to be the target portion of the thermal hydraulic analysis. Specifically, the DIMM areas51-1to51-6and the power supply board52are the target of the thermal hydraulic analysis. The thermal hydraulic analysis is performed in the state in which the cooling air is taken in obliquely relative to the front, passes over the printed circuit board40, and flows in a direction oblique to the back surface.

FIG. 7is a schematic diagram illustrating the results of the thermal hydraulic analysis.FIG. 7illustrates the flow of the cooling air is indicated by lines. As illustrated inFIG. 7, with the system board200in which an air intake port is not offset, a part of the cooling air flowing in the DIMM area51-2flows toward the DIMM area51-1during the flowing, and thus the DIMM area51-2is not effectively used in terms of the cooling.

In contrast, with the system board200in which an air intake port is offset, there is no cooling air that deviates from the DIMM area51-2into the DIMM area51-1, and thus the cooling air is uniformly flowing in the DIMM area.

In the following, the improvement of the cooling effect of the DIMMs due to the offsetting of the air intake port will be described.FIG. 8is a schematic diagram illustrating DIMMs installed in the DIMM areas51-1to51-6. In the DIMM area51-1, four DIMMs1to4are mounted; in the DIMM area51-2, eight DIMMs5to12are mounted; and in the DIMM area51-3, four DIMMs13to16are mounted. Similarly, in the DIMM area51-4, four DIMMs17to20are mounted; in the DIMM area51-5, eight DIMMs21to28are mounted; and in the DIMM area51-6, four DIMMs29to32are mounted.

FIG. 9is a schematic diagram illustrating the differences between cooling effects obtained when an air intake port is offset and when the air intake port is not offset. InFIG. 9, the temperatures of the DIMMs1to32are compared between the system board201in which the position of the air intake port is offset and the system board200in which the position of the air intake port is not offset. The variation (ΔT) in the temperatures between all of the DIMMs mounted on the system board200is 20° C., whereas the variation in the temperatures between all of the DIMMs mounted on the system board201is 16° C. Accordingly, the variation in the temperatures can be reduced by offsetting the air intake port.

As described above, when the server100and the system boards201according to the first embodiment introduce cooling air over the printed circuit board having mounted thereon the heat-generating components, the server100and the system boards201uses an air intake port arranged, by being offset, in the direction from the front of the heat-generating components to the cooling air stream.

Accordingly, if the cooling air is supplied from a direction that is oblique with respect to the side plate that is the wall of the system board201, the server100and the system board201can efficiently cool the heat-generating components.

[b] Second Embodiment

FIG. 10is a schematic diagram illustrating the configuration of a system board that is an electronic device according to a second embodiment. The system board202illustrated inFIG. 10includes ducts71each of which are arranged near each of the air discharge ports62-1to62-3. Furthermore, a duct72that has an air guiding duct is arranged between the DIMM areas51-1to51-3and the DIMM areas51-4to51-6on the power supply board52. Because the configuration of the system board202is the same as that of the system board201described in the first embodiment, components that are the same as those in the first embodiment are assigned the same reference numerals; therefore, a description thereof is omitted.

In the second embodiment, the system board202includes both the ducts71and the duct72; however, the system board202may also include either one of the ducts71or the duct72. First, the ducts71will be described.

FIG. 11is a schematic diagram illustrating the system board202that includes the ducts71, compared with the system board201that does not include the duct71. The system board202has the structure in which the ducts71are arranged on the downstream side of the cooling air, i.e., on the air discharge port side.

To allow the cooling air to intensively flow, on the downstream side, in the DIMM areas51-4to51-6, walls are arranged in accordance with the arrangements of the DIMM areas51-4to51-6in each of the ducts71and positions corresponding to the air discharge ports of the DIMM areas other than the DIMM areas51-4to51-6are covered.

With these ducts71, the cooling air flowing on the downstream side of the printed circuit board40can be concentrated in the DIMM areas51-4to51-6, thereby it is possible to efficiently cools the DIMMs arranged on the downstream side where the temperature is higher than the upstream side.

Furthermore, by arranging a duct that efficiently allows the cooling air to make contact on the upstream side, i.e., make contact along some of the DIMM area on the air intake port side, the cooling effect can be further improved.

FIG. 12is a schematic diagram illustrating a system board in which ducts are arranged on the air discharge port side and the air intake port side. The system board203illustrated inFIG. 12includes ducts73on the downstream side of the DIMM area51-1and the DIMM area51-3. The cooling air that is introduced in a direction that is oblique with respect to the system board203changes its flow direction when the cooling air makes contact with the ducts73and cools the DIMMs, and thus the cooling effect is improved.

FIG. 13is a schematic diagram illustrating the duct72in which an air guiding duct is arranged.FIG. 14is a sectional view of a system board204taken along line A-A′ inFIG. 13.FIG. 15is a sectional view of the system board204taken along line B-B′ inFIG. 13.

The system board204illustrated inFIGS. 13 to 15includes the duct72for cooling the power supply board52between the DIMM areas51-1to51-3arranged on the upstream side and the DIMM areas51-4to51-6arranged on the downstream side. Then, an air guiding duct74, i.e., a local tunnel, is arranged near each of the center of the DIMM areas51-4and51-5in which the duct72is arranged. This air guiding duct74can allow the cooling air that is not affected by heat generated from the power supply board52to be supplied in the DIMM area on the downstream side.

In the following, as a comparative example of the system board204, a case will be described in which the duct72that does not have an air guiding duct is arranged on the system board201.FIG. 16is a schematic diagram illustrating the system board201in which the duct72that does not have an air guiding duct is arranged.FIG. 17is a sectional view of the system board201taken along line A-A′ inFIG. 16.FIG. 18is a sectional view of the system board201taken along line B-B′ inFIG. 16.

With the duct72that does not have an air guiding duct, the cooling air is supplied to the DIMM area on the downstream side via the vicinity of the power supply board52. Accordingly, the temperature of the cooling air rises due to the heat generated from the power supply board52.

In the following, a modification of the shape of the air guiding duct will be described.FIGS. 19 and 20illustrate specific examples of the structure in which the air guiding ducts have an angle (taper). Each of air guiding ducts75illustrated inFIG. 19has an air intake opening that is greater than an air discharge opening. Specifically, each of the air guiding ducts75has an angle on one end. The angle preferably has an angle on the upstream side in the direction in which the cooling air flows.

The configuration of air guiding ducts76illustrated inFIG. 20is the same as that of each of the air guiding ducts75in that the air intake opening is greater than the air discharge opening; however, each of the air guiding ducts76has an angle on both sides of the air guiding duct. Accordingly, the cooling air can be supplied to the air discharge port by collecting the cooling air from all of the corresponding DIMM areas.

By making the air intake opening greater than the air discharge opening as with the air guiding ducts75and the air guiding ducts76, the flow velocity of the cooling air supplied on the air discharge side increases, thus improving the cooling efficiency.

As described above, the system board202according to the second embodiment includes the ducts71functioning as straightening vanes of the cooling air in the vicinity of the electronic components arranged on the downstream side. The duct71can reduce a temperature rise of the electronic components arranged on the air discharge side where the temperature tends to rise compared with the temperature on the air intake side, and thus it is possible to efficiently and uniformly cool all of the electronic components mounted on the system board202.

Furthermore, the system board202according to the second embodiment includes the ducts73functioning as straightening vanes of the cooling air in the vicinity of the electronic components arranged on the upstream side. With the ducts73, it is possible to control the cooling air on the air intake side and thus is possible to reduce the temperature rise of the electronic components arranged on the air discharge side, thus efficiently and uniformly cooling all of the electronic components mounted on the system board203.

Furthermore, for the electronic components arranged on the downstream side where the temperature becomes relatively high due to the temperature rise of the electronic components arranged on the upstream side, the system board202according to the second embodiment increases the flow velocity of the cooling air by focusing the flow of the cooling air to the midpoint between the upstream side and the downstream side. Accordingly, even when the cooling air whose temperature rises due to the heat generated from the electronic components arranged on the upstream side makes contact with the electronic components arranged on the downstream side, it is possible to remove the heat generated from the electronic components arranged on the downstream side as much as possible.

Furthermore, by installing the system boards202and203according to the second embodiment in a server, it is possible to reduce the heat generated from the entire server.

FIG. 21is a schematic diagram illustrating the configuration of a system board that is an electronic device according to a third embodiment. The system board204illustrated inFIG. 21has the structure in which fins82are arranged in the water cooling jackets81and the water cooling pipes. Because the configuration of the system boards according to the third embodiment is the same as that of the system boards201to203described in the first and second embodiments, components that are the same as those in the first and second embodiments are assigned the same reference numerals; therefore, a description thereof is omitted.

The temperature of the water cooling jackets81and the water cooling pipe is lower than that of the DIMMs. Accordingly, with the system board204, the cooling air introduced from the air intake port is cooled by making contact with the fin82. Accordingly, the cooling air can efficiently cools the DIMM.

FIG. 22is a schematic diagram illustrating of the structure of fins that have an angle corresponding to the inflow angle of cooling air. With a system board205illustrated inFIG. 22, fins83have an angle corresponding to an inflow angle of the cooling air. Accordingly, it is possible to reduce the flow velocity of the cooling air when the cooling air makes contact with the fins83, thus cooling the DIMMs with cooling air having the high velocity and low temperature.

As described above, for the electronic components arranged on the downstream side where the temperature becomes relatively high due to the temperature rise of the electronic components arranged on the upstream side, the system boards204and205according to the third embodiment decreases the temperature of the cooling air by allowing the water cooling jackets81, i.e., a cooling structure part, arranged on the upstream side of the electronic components that are arranged on the downstream to efficiently cool and by passing the cooling air flowing therein through the cooling structure part.

By cooling the temperature of the cooling air using the water cooling jackets or the cooling tubes in this way and by causing the cooling air having a lower temperature to make contact with the electronic components arranged on the downstream side of the water cooling jackets or the cooling tubes, it is possible to improve the cooling efficiency of the components to be cooled.

Furthermore, by installing the system boards202and203according to the second embodiment in a server, it is possible to reduce the heat generated from the entire server.

As described in the above embodiments, with the electronic device and the complex electronic device disclosed in the present invention, by offsetting the inlet of the cooling air, the inflow of the cooling air is performed smoothly, and thus it is possible to more efficiently and more uniformly bring the cooling air into contact with the electronic components to be cooled.

Furthermore, by controlling the direction or the velocity of the cooling air in accordance with the arrangement of the ducts and by using the cooling of the cooling air itself generated by using the cooling structure parts, the effect of the cooling is further improved, and thus cooling is efficiently performed.

Accordingly, because the heat-generating components mounted on the electronic device can be uniformly cooled, the variation in the temperature of the components can be reduced, and thus the reliability of the components is improved. Furthermore, by efficiently performing the cooling, an amount of inefficient cooling air can be reduced. Accordingly, the number of fans that send the cooling air can be reduced, thus saving electrical power, reducing noises, and reducing the size of the structure.

The first, second, and third embodiments are only for an example; therefore, the disclosed technology can be used by appropriately being changed. For example, in the first, second, and third embodiments, a case has been described in which an amount of offset of the air intake port is fixed. However, the amount of offset of the air intake port can be changed by arranging a sliding window member at the air intake port.

According to one aspect of the electronic device and the complex electronic device disclosed by this application, the electronic device and the complex electronic device efficiently cool a heat-generating component by supplying cooling air at an angle that is oblique with respect to a wall of a casing of the electronic device.