JP5720443B2 - Electronics - Google Patents

Description

  The present invention relates to an electronic device having a plurality of electronic components therein. The present invention provides an electronic device with excellent cooling efficiency of electronic components.

  In recent years, in various product fields, electronic devices have been mounted with a large number of electronic components (typically semiconductor chips). In particular, an electronic device that controls a motor, generally called a “controller”, uses a large number of semiconductor chips and a motor that requires a large amount of power to be controlled. Large amount. Therefore, many electronic devices have a cooling structure in the housing. Also, recent computers (particularly supercomputers) have dramatically increased the amount of heat generated as the CPU performance has increased, and many computers have a cooling structure.

  For example, Patent Document 1 discloses an electronic device with a devised cooling structure. This technique gradually changes the volume of the refrigerant flow path from upstream to downstream. By adopting such a structure, the flow rate of the refrigerant is faster in the downstream than in the upstream, and the downstream cooling effect is improved.

International Publication WO 00/16397

  Usually, an electronic device including a cooling mechanism includes a pump for circulating a refrigerant or a fan (when the refrigerant is a gas). The technique disclosed in Patent Document 1 also circulates the refrigerant using a pump. The present invention provides a technique for circulating a refrigerant without requiring a pump (or a fan). Note that the technology disclosed in this specification does not exclude the use of a pump (or fan). When a pump (or fan) is combined with the technology disclosed in this specification, a force for circulating a refrigerant acts in addition to the pump, so that an electronic device with higher cooling efficiency than a conventional cooling structure can be provided. The present invention provides a technique for improving the cooling efficiency in a sense including the refrigerant circulation capability.

One embodiment of the technology disclosed in this specification can be embodied in the following electronic device. The electronic device includes a heat radiating plate disposed above the housing, a refrigerant cooling unit disposed above the housing and adjacent to the heat radiating plate, and a downflow path that guides the refrigerant from the refrigerant cooling unit to the lower portion of the housing. And an ascending channel that guides the refrigerant that has moved downward through the descending channel to the refrigerant cooling unit. In the refrigerant cooling section, the temperature of the refrigerant is lowered (cooled) by the heat radiation from the heat sink. In this electronic device, an electronic component (typically a semiconductor chip) to be cooled is arranged on the inner wall of the ascending channel, and the thermal conductivity of the wall member forming the descending channel is attached to the electronic component. It is smaller than the thermal conductivity of the rising channel wall member . In other words, the side wall of the ascending flow path is composed of a member (plate material) having a higher thermal conductivity than the member (plate material) constituting the descending flow path. In this electronic device, the casing forms part of the inner walls of the ascending flow path and the descending flow path, and the thermal conductivity of the plate material that forms the upper side of the casing forms the lower side of the casing. It is higher than the thermal conductivity of the plate material.

  Here, “upper case” and “lower case” mean a case internal part located vertically above and a case internal part located vertically below. Moreover, it is not necessary for all the members constituting the ascending flow path to satisfy the above relationship (that is, having a higher thermal conductivity than the members constituting the descending flow path). It is only necessary that a part of the descending channel and a part of the ascending channel satisfy the above relationship. Preferably, 50% of the descending channel and 50% of the ascending channel satisfy the above relationship. Further, when one member separates the descending channel and the ascending channel, such a member is handled as a member constituting the descending channel. This is to prevent heat exchange between the refrigerant passing through the ascending channel and the refrigerant passing through the descending channel.

In this electronic device, the refrigerant in the ascending channel takes heat away from the electronic component, and its own temperature rises. The refrigerant whose temperature has risen decreases in density due to thermal expansion and moves upward. The refrigerant that has reached the refrigerant cooling section above the casing is cooled by the heat radiating plate, moves toward the lower flow path so as to be pushed out by the high-temperature refrigerant that has gone up the upper flow path, and moves downward. That is, in this electric device, the refrigerant is circulated by the principle of thermal convection. By utilizing thermal convection, the refrigerant can be circulated without requiring a pump (fan). Further, the structure in which the upper side has a high thermal conductivity and the lower side has a low thermal conductivity promotes cooling of the refrigerant above the inside of the housing, and promotes the temperature rise of the refrigerant below. Therefore, the circulation of the refrigerant according to the principle of thermal convection is promoted. Or if the technique which this specification discloses is applied to a cooling mechanism with a pump (or fan), cooling efficiency can be improved rather than the conventional electronic device provided with an equivalent pump.

  Furthermore, in the above electronic device, electronic components are arranged on the inner wall of the ascending flow path. The heat of the electronic component spreads quickly on the wall surface of the ascending channel by the wall member having high thermal conductivity. Therefore, in the ascending flow path, heat exchange between the refrigerant and the electronic component is promoted, the electronic component is efficiently cooled, and the temperature of the refrigerant rises more. On the other hand, the wall member that forms the descending channel has a lower thermal conductivity than the wall member that forms the ascending channel, so that the temperature rise of the refrigerant is suppressed in the descending channel. This electronic device promotes thermal convection by using a material having a higher thermal conductivity than the latter for the member constituting the ascending flow path and the member constituting the descending flow path. Improve the cooling capacity.

  The refrigerant may be a gas but is preferably a liquid. Liquid has a higher cooling capacity than gas, and convection tends to occur. As the refrigerant, for example, a fluorine-based inert liquid is preferable.

  In another aspect of the technology disclosed in this specification, a plurality of plate members on which electronic components are mounted are arranged so as to overlap in the vertical direction, and a plurality of plate members adjacent in the vertical direction constitute upper and lower walls of the ascending flow path. The rising channel of the stage is formed, and the connection ports of the rising channel adjacent to the upper and lower sides may be alternately arranged from the lower stage to the upper stage so that the refrigerant meanders and flows in the upward path. . Furthermore, the descending flow path may be linear from the top to the bottom of the housing. By securing a long ascending channel, many electronic components can be cooled, and a low temperature coolant can be quickly supplied to the lower part of the housing by a short descending channel.

The typical cross section of the electronic device of 1st Example is shown. The typical cross section of the electronic device of 2nd Example is shown.

  FIG. 1 is a schematic cross-sectional view of an electronic device 100 according to the first embodiment. In the coordinate system shown in the figure, the X and Y axes indicate the horizontal direction, and the Z axis indicates the vertical direction. The electronic device 100 is a controller for an automobile or a robot, and has a large number of electronic components 22. Many of the electronic components 22 are semiconductor chips, and these electronic components 22 are mounted on an electronic substrate 24. In FIG. 1, three electronic boards 24 are depicted, but the reference numeral 22 is given only to the uppermost electronic board 22, and the reference numerals are omitted for the electronic components mounted on the middle and lower electronic boards 24. doing. Various electronic components included in the electronic device 100 can take various shapes and sizes. In FIG. 1, a plurality of electronic components 22 representing a large number of component groups are all schematically represented by the same simple rectangle. Please note that.

  First, the structure of the electronic device 100 will be outlined. In the electronic device 100, the interior of the housing 4 is filled with the refrigerant, and the refrigerant circulates through the flow path 12, thereby cooling the electronic component 22. The flow path 12 is configured to move the refrigerant between the upper side and the lower side of the housing. The heat sink 2 is provided on the upper surface of the upper wall of the housing 4, and the refrigerant flowing above the housing 4 is cooled by the action of the heat sink 2. Since the density of the cooled refrigerant increases, the refrigerant becomes heavier and moves through the descending flow path 12a to the lowermost flow path 12b of the housing. On the contrary, the refrigerant flowing through the rising channels 12c and 12d takes heat from the electronic component 22 and the temperature rises. The refrigerant whose temperature has increased decreases in density and moves to the flow path 12e at the top of the housing through the rising flow paths 12c and 12d. The flow path 12e at the top of the housing is adjacent to the heat radiating plate 2, where the refrigerant is cooled. Hereinafter, the flow path 12e at the top of the housing may be referred to as a refrigerant cooling unit 12e. With the above structure, in the electronic device 100, the refrigerant circulates due to thermal convection without requiring a driving force. The white arrows in FIG. 1 (and FIG. 2) indicate the flow of the refrigerant. Hereinafter, the internal structure of the electronic device 100 will be described in detail.

  The electronic board 24 on which the electronic component 22 is mounted is placed on partition walls (plate members) 8 a to 8 c that spread in the horizontal direction, and the horizontal partition walls 8 a to 8 c are fixed in the housing 4. The horizontal partition walls 8 a to 8 c and the vertical partition wall 6 are walls that partition the space in the housing 4. A refrigerant flow path is formed in the housing 4 by the partition walls. The horizontal partition walls 8a to 8c and the vertical partition wall 6 are directly fixed to the inner wall of the housing 4 (horizontal partition wall 8b), or fixed to the housing 4 via support spacers 28a and 28b (horizontal partition wall 8a, vertical). Septum 6). The horizontal partition wall 8 a is fixed to the vertical partition wall 6. The horizontal partition 8c is fixed to the vertical partition 6 and the support spacer 28b.

  The three horizontal partition walls 8a to 8c are arranged so as to overlap in the vertical direction, and a refrigerant flow path is formed above and below each horizontal partition wall. That is, the upper and lower horizontal partition walls constitute the upper and lower walls of the ascending channel to form a plurality of stages of channels. The lowermost flow path 12 b is formed by the lowermost horizontal partition wall 8 a and the lower wall of the housing 4. The lowermost horizontal partition wall 8a and the middle horizontal partition wall 8b form a second-stage flow path 12c. A third-stage flow path 12d is formed by the middle horizontal partition wall 8b and the uppermost horizontal partition wall 8c. The uppermost horizontal partition wall 8c and the upper wall of the housing 4 form a refrigerant cooling unit 12e (uppermost channel 12e).

  A communication port 14a between the lowermost flow channel 12b and the second-stage flow channel 12c is provided on the left side of the housing in FIG. A communication port 14b between the second-stage flow path 12c and the third-stage flow path 12d is provided on the right side of the housing in FIG. A communication port 14c between the third-stage flow path 12d and the refrigerant cooling section 12e is provided on the left side of the housing in FIG. That is, the communication ports 14a to 14c of the upper and lower adjacent flow paths are staggered from the bottom to the top in the housing 4 as viewed from the horizontal direction, such as the left end-right end-left end of the flow path end. Has been placed.

  The vertical partition wall 6 is positioned on the right side inside the housing 4 in FIG. 1 and separates the ascending flow paths 12c and 12d from the descending flow path 12a. A descending flow path 12 a is formed by the vertical partition wall 6 and the right side wall of the housing 4. The downward flow path 12a extends linearly from the upper part to the lower part inside the housing.

  The entire electronic substrate 24 including the electronic component 22 is covered with an insulating film. As described above, the inside of the housing 4 is filled with the refrigerant liquid (fluorine-based inert liquid). However, the insulation of the electronic component 22 is not broken by the refrigerant due to the presence of the insulating film.

  As described above, the refrigerant naturally convects inside the housing by thermal convection. In the electronic device 100, in order to promote thermal convection, the material of the horizontal partition walls 8a and 8b that form the ascending flow path 12c, the material of the partition wall 6 that forms the descending flow path, and the partition wall 8c that forms the uppermost flow path 12e. Is different. The thermal conductivity of the partition wall 6 forming the descending flow path 12a is smaller than the thermal conductivity of the horizontal partition walls 8a and 8b forming the ascending flow path 12c to which the electronic component 22 is attached. Specifically, the partition walls 6 are made of carbon fiber reinforced plastic (CFRP), and the horizontal partition walls 8a and 8b are made of aluminum. The thermal conductivity of the carbon fiber reinforced plastic is approximately 50 [W / mK], and the thermal conductivity (thermal conductivity) of aluminum is approximately 200 [W / mK].

  Since the horizontal barrier ribs 8a and 8b have high thermal conductivity, the heat of the electronic component 22 on the electronic substrate 24 fixed to the barrier ribs is easily transmitted to the horizontal barrier ribs 8a and 8b. Therefore, the electronic components fixed to the horizontal partition walls 8a and 8b are quickly cooled, and the temperature of the refrigerant rises faster accordingly. If the temperature of the refrigerant in the ascending channel rises quickly, the rising speed of the refrigerant temperature increases. On the other hand, the vertical partition 6 constituting the descending flow path 12a has a low thermal conductivity. The refrigerant in the refrigerant cooling part 12e adjacent to the heat sink 2 is cooled by the action of the heat sink. The refrigerant whose temperature has decreased is directed to the descending flow path 12a so as to be pushed out by the refrigerant flowing up the ascending flow paths 12c and 12d. Since the side wall (vertical partition wall) of the descending flow path 12a has low thermal conductivity, the refrigerant in the low temperature state moves toward the flow path 12b at the bottom of the casing while maintaining the temperature. Then, the low-temperature refrigerant goes to the ascending flow path and cools the electronic component again. The electronic substrate 24 on which electronic components are mounted is also made of a material having high thermal conductivity.

  As described above, in the electronic device 100, the plate material (horizontal partition walls 8a and 8b) that defines the ascending flow paths 12c and 12d is made of a material having higher thermal conductivity than the plate material (vertical partition wall 6) that defines the descending flow path 12a. Making it promotes thermal convection. The electronic device 100 can cool the electronic component by efficiently circulating the refrigerant without requiring power from a pump or the like.

  An electronic apparatus 200 according to the second embodiment will be described with reference to FIG. The electronic device 200 in FIG. 2 has the same structure as the electronic device 100 in FIG. 1 except that the form of the housing 204 is different from the electronic device 100 in FIG. It should be noted that in FIG. 2, some of the same parts as those shown in FIG. 1 are omitted.

  The housing 204 of the electronic device 200 is composed of two parts, a housing upper part 204a and a housing lower part 204b. The boundary between the case upper part 204a and the case lower part 204b is above half the height of the entire case. More precisely, the boundary between the case upper part 204a and the case lower part 204b is higher than the position of the uppermost horizontal partition wall 8c. The heat sink 2 is provided in the housing | casing upper part 203a. Therefore, in other words, the housing part corresponding to the coolant cooling unit 12e corresponds to the housing upper part 204a. The plate material constituting the housing upper portion 204a is made of a material whose thermal conductivity is higher than the thermal conductivity of the plate material constituting the housing lower portion 204b. In the present embodiment, the housing upper part 204a is made of aluminum, like the horizontal partition walls 8a, 8b, and the housing lower part 204b is made of carbon fiber reinforced plastic, like the vertical partition walls 8c.

  Since the heat conductivity of the housing upper part 204a is high, heat radiation by the heat radiating plate 2 is promoted, and cooling of the refrigerant in the refrigerant cooling unit 12e is promoted. On the other hand, since the heat conductivity of the housing lower portion 204b is low, the heat released by the electronic component 22 is not dissipated outside the housing, and most of it contributes to raising the temperature of the refrigerant. That is, due to the structure of the housing 204 in which the upper portion has high thermal conductivity and the lower portion has low thermal conductivity, cooling of the refrigerant is promoted above the inside of the housing, and temperature rise of the refrigerant is promoted below. In the electronic device 200, the housing 204 having the above structure promotes natural convection of the refrigerant. This improves the cooling efficiency of the electronic component.

  In other words, in the case lower part 204b, the heat dissipated to the outside of the case is reduced, and the heat released by the electronic component 22 is absorbed by the refrigerant as much as possible, thereby raising the temperature of the refrigerant and promoting thermal convection. . On the other hand, the housing upper part 204a is designed to release as much heat as possible to the outside of the housing.

  Points to note about the electronic device of the embodiment will be described. In all the wall members constituting the ascending flow path, the thermal conductivity does not need to be higher than that of the wall member constituting the descending flow path. The wall member that constitutes the descending channel in the part of the wall member that constitutes the ascending channel, preferably 50% or more, or the wall member that constitutes the ascending channel in the lower half region of the casing It should be higher than the thermal conductivity of. By increasing the thermal conductivity of the wall member upstream of the ascending channel, convection can be caused efficiently.

  The technology disclosed in this specification can be applied to various types of electronic devices, but can be applied to electronic devices that generate a large amount of heat, for example, motor controllers and inverters including a plurality of power IGBTs or supercomputers including a large number of high-speed CPUs. It is preferable to do.

  The plate material with low thermal conductivity is not limited to carbon fiber reinforced plastic. A ceramic material having a lower thermal conductivity than carbon fiber reinforced plastic may be used. Similarly, the plate material having high thermal conductivity is not limited to aluminum. It is even better if the horizontal partition walls (horizontal partition walls forming the ascending flow path), the upper part of the housing, and the heat sink are made of copper having a higher thermal conductivity than aluminum. In this specification, the expressions “high thermal conductivity” and “low thermal conductivity” are relative when comparing the plate material constituting the upflow channel and the plate material constituting the downflow channel. Please note that. “High thermal conductivity” means that the thermal conductivity is higher than that of the plate material forming the descending flow path, or higher than that of the plate material constituting the lower part of the housing. “The rate is low” means that the thermal conductivity is lower than the plate material forming the ascending flow path, or the thermal conductivity is lower than the plate material forming the upper part of the housing.

  The technology disclosed in this specification relates to an electronic device, but can be expressed as being related to a cooling structure of an electronic device if expressed more purpose-oriented.

  Specific examples of the present invention have been described in detail above, but these are merely examples and do not limit the scope of the claims. The technology described in the claims includes various modifications and changes of the specific examples illustrated above. The technical elements described in this specification or the drawings exhibit technical usefulness alone or in various combinations, and are not limited to the combinations described in the claims at the time of filing. In addition, the technology exemplified in this specification or the drawings can achieve a plurality of objects at the same time, and has technical usefulness by achieving one of the objects.

2: Heat radiation plate 4: Housing 204a: Upper housing portion 204b: Lower housing portion 6: Vertical partition walls 8a, 8b, 8c: Horizontal partition walls 12a: Flow path (downward flow path)
12b: channel (lowermost channel)
12c, 12d: channel (ascending channel)
12e: Flow path (refrigerant cooling part)
14a, 14b, 14c: Contact port 22: Electronic component 24: Electronic board 28a, 28b: Support spacer 100, 200: Electronic device 204: Housing 204a: Upper housing 204b: Lower housing

Claims (2)

An electronic device having a plurality of electronic components in a housing,
A heat sink disposed above the housing;
A refrigerant cooling part disposed above the housing and adjacent to the heat sink;
A descending flow path for guiding the refrigerant from the refrigerant cooling part to the lower part of the housing;
An ascending channel that guides the refrigerant that has moved down the casing through the descending channel to the refrigerant cooling unit, and
With
Electronic components to be cooled are arranged on the inner wall of the ascending flow path,
The thermal conductivity of the wall members forming the downward flow path, and smaller Kuna' than the thermal conductivity of the wall member forming a rising flow path in which the electronic component is mounted,
The housing forms part of the inner walls of the ascending channel and the descending channel, and the thermal conductivity of the plate material constituting the upper side of the housing is higher than the thermal conductivity of the plate material constituting the lower side of the housing Electronic equipment characterized by high price.   A plurality of plate members on which electronic components are mounted are arranged so as to overlap in the vertical direction, and the plate materials adjacent to each other in the vertical direction constitute the upper and lower walls of the ascending channel to form a plurality of rising channels, The electronic device according to claim 1, wherein communication ports of the upward and downward adjacent upward flow paths are alternately arranged from the lower stage toward the upper stage so as to meander and flow in the upward flow path.

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