JP2008140831A - Heat-sink structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a heat-sink structure capable of circulating a fluid without deteriorating an energy efficiency. <P>SOLUTION: The heat-dissipating structure has: a base section 1; a first heat-dissipating section A<SB>1</SB>being placed in the first region of the base section and dissipating a heat; and a second heat-dissipating section A<SB>2</SB>being placed in a second region adjacent to the first region and dissipating the heat. The quantity of heat dissipated per unit area of the base section in the first heat-dissipating section is made larger than that in the second heat-dissipating section. <P>COPYRIGHT: (C)2008,JPO&INPIT

Description

  The present invention relates to a heat dissipation structure, and more specifically to a heat dissipation structure for suppressing a temperature increase of a cooling target such as various semiconductor devices.

  Many semiconductor devices are used in high-speed data processing arithmetic devices, communication devices, automobiles, and the like, and a lot of heat is generated from these semiconductor devices due to power loss. In these apparatuses, the problem of temperature rise in semiconductor devices has become serious as the processing speed increases, the capacity of the apparatus increases (large current), and the size of the apparatus decreases. If sufficient heat dissipation is not performed, the temperature of the semiconductor device rises and normal operation cannot be performed.

The temperature rise of the semiconductor device has been a problem for a long time, and many efforts have been made. For example, in order to improve the heat dissipation performance of the parallel radiating fins used for radiating semiconductor devices, a structure in which a baffle plate for generating turbulence is attached so that the airflow does not pass straight through the radiating fin gap, Or the structure of the cylindrical fin of a staggered arrangement is disclosed (patent document 1). According to this structure, a turbulent flow is generated by the baffle plate or the staggered columnar fins attached obliquely, and the heat dissipation effect can be enhanced. In addition, when cooling multiple substrates vertically mounted with a large number of semiconductor devices, when cooling medium air flows from the lower part to the upper part, heat is dissipated by unheated air in the lower part. As a result of the replacement, the temperature rises, so that the cooling capacity is lowered, and a problem may occur in the operation of the upper semiconductor device. In order to solve this, the cross-sectional area of the flow path is narrowed at the upper part by arranging different slopes depending on the substrate position so that the space between the plurality of substrates becomes wider (and therefore narrower). By doing so, the proposal of the policy of raising the flow velocity in the upper part and ensuring the cooling capacity has been made (Patent Document 2). According to this measure, the flow velocity of air passing through the space between the substrates at the upper portion becomes large at the upper portion, and the heat dissipation capability at the upper portion can be ensured even if the temperature of the air rises. In the above heat dissipation structure, it is assumed that a fan or the like that forcibly circulates the fluid is disposed anywhere in the flow path through which the fluid of the heat medium flows. Although the upper narrow space increases the flow resistance, it is forcedly circulated by these fans or the like, so that the heat dissipation effect can be enhanced as described above.
JP 2001-345585 A Japanese Patent Laid-Open No. 3-85796

  In the above data processing arithmetic device, communication device, etc., when a fan or pump that forcibly circulates fluid is used, the power consumed by the fan or pump cannot be ignored and is added to the power lost in the semiconductor device. Energy efficiency is reduced. However, in a large-scale data processing arithmetic unit or the like, many semiconductor devices are arranged. Therefore, the temperature distribution becomes non-uniform unless the fluid is circulated, and the semiconductor device at a location where the temperature is locally high does not operate normally. This will cause trouble. For this reason, development of the heat radiating device which can circulate a fluid, without reducing energy efficiency has been desired.

  An object of this invention is to provide the thermal radiation structure which can circulate a fluid, without reducing energy efficiency.

  The heat dissipating structure of the present invention is located in the base, the first heat dissipating part located in the first region of the base and dissipating heat, and the base in the second region adjacent to the first region. And a second heat dissipating part that dissipates heat. The heat dissipation amount per base unit area in the first heat dissipating part is larger than the heat dissipating amount per base unit area in the second heat dissipating part.

  According to said structure, in each of the 1st and 2nd thermal radiation part, when fins are arrange | positioned, for example, heat transfer is performed between the fin surface (heat transfer surface) and the fluid, and the fluid is a natural convection. However, natural convection heat transfer occurs on the heat transfer surface. In addition, since the heat dissipation amount per base unit area in the first heat radiating portion is larger than that in the second heat radiating portion, the fluid temperature in the first heat radiating portion is higher than the fluid temperature in the second heat radiating portion. become. As a result, a driving force for fluid movement is generated between the areas of the heat dissipation structure due to the temperature difference, and circulation is performed within the range of the heat dissipation structure without arranging a fan or pump, thus reducing energy efficiency. Without this, the heat radiation amount in the heat radiation structure can be increased. How the fluid moves varies greatly depending on the surrounding boundary conditions, the direction of gravity, etc., but within the range of the heat dissipation structure for the above fluid without a pump or fan due to the above driving force. Therefore, a driving force for circulation is generated. When forced circulation is performed in the region of the heat dissipation structure, the amount of heat transfer is greatly improved, so that the amount of heat dissipation to the fluid can be increased without sacrificing energy efficiency.

  The first heat radiating part and the second heat radiating part may have any form as long as the heat radiating amount per substrate unit area is high in the first heat radiating part. A form with a continuous gradient of the heat radiation amount per area may be used, or a form in which the heat radiation amount per unit area of the substrate is changed stepwise. Further, within the range of the heat dissipation structure, the discharge per unit area of the substrate is intermediate between the first heat dissipation portion and the second heat dissipation portion, or higher than any of these, or lower than any of these. It goes without saying that there may be other regions having a calorific value.

  Another heat dissipating structure of the present invention has a base, a first heat dissipating part having a fin standing in the first region of the base, and a fin standing in the second region adjacent to the first region in the base. A second heat radiating section. And the surface area of the fin per base unit area in a 1st thermal radiation part and the surface area of the fin per base unit area in a 2nd thermal radiation part was made larger, It is characterized by the above-mentioned.

  According to said structure, it becomes possible to make the temperature of the fluid in a 1st thermal radiation part higher than the temperature of the fluid in a 2nd thermal radiation part. For this reason, as described above, a driving force for fluid movement within the range of the heat dissipation structure due to the temperature difference is generated, and forced circulation is performed in the region of the heat dissipation structure without arranging a fan or a pump. The amount of heat radiation can be increased without reducing the energy efficiency.

  The first heat radiating portion and the second heat radiating portion may have any form as long as the surface area is high in the first heat radiating portion, and a continuous gradient to the surface area in the first and second heat radiating portions. It may be a form with a mark, or a form in which the surface area changes stepwise. In addition, within the range of the heat dissipation structure, the intermediate surface between the first heat dissipating part and the second heat dissipating part, or higher than any of these, or lower than any of these, has the above surface area. It goes without saying that there may be areas.

  Moreover, it can comprise so that the fin height of said 1st thermal radiation part and the fin height of the 2nd thermal radiation part may be arrange | equalized. Thereby, the fluid temperature in the 1st heat radiating part can be reliably made higher than the fluid temperature in the 2nd heat radiating part, and manufacture of a heat radiating structure provided with a base and a fin can be facilitated.

  Moreover, it is good also as a structure where the fin height of all or one part of the fin of a 1st thermal radiation part is higher than the fin height of a 2nd thermal radiation part. Thereby, the structure which makes it possible to make the heat radiation amount per base unit area of the first heat radiation portion larger than that of the second heat radiation portion can be easily obtained.

  Another heat dissipating structure of the present invention is a structure that conducts heat in contact with a fluid, and includes a base, a first heat dissipating part that is located in a first region of the base and dissipates heat, and a base. And a second heat dissipating part located in a second region adjacent to the first region to dissipate the heat. And the temperature of the fluid in a 1st thermal radiation part was made to become higher than the temperature of the fluid in a 2nd thermal radiation part, It is characterized by the above-mentioned.

  According to said structure, in each of the 1st and 2nd thermal radiation part, when fins are arrange | positioned, for example, heat transfer is performed between the fin surface (heat transfer surface) and the fluid, and the fluid is a natural convection. However, natural convection heat transfer occurs on the heat transfer surface. In addition, since a temperature difference is generated between the fluid in the first heat radiating portion and the fluid in the second heat radiating portion, a driving force is generated that breaks the stationary balance of the fluid that is retained during natural convection at each position.

  According to the heat dissipation structure of the present invention, the fluid that is the cooling medium can be circulated without reducing the energy efficiency.

(Embodiment 1)
FIG. 1 is a perspective view showing a heat dissipation structure 10 according to Embodiment 1 of the present invention. FIG. 2 is a plan view of the heat dissipation structure 10 of FIG. The heat dissipation structure 10 includes a base 1 and standing wall-like fins 3 and 5 that stand on the base 1. The flow path through which the fluid in contact with the base 10 and the fins 3 and 5 flows may be formed in any way as long as the fluid contacts the base and the fins. Can be set.

In heat dissipation structure 10 in the present embodiment, while the standing wall-shaped fins 3 are arranged continuously over the first heat radiation member A ₁ and the second heat radiating portion A _2, vertical wall-like fins 5 It is limited only to the first heat radiation member a _1, the second heat radiating portion a ₂ does not extend. Therefore, the surface area of the (base + standing wall-shaped fins) per base unit area in the first heat radiation member A ₁ is per base unit area in the second heat radiating portion A ₂ of the (base + standing wall-shaped fins) It becomes larger than the surface area.

Assuming that the height of the standing wall-like fins 3 and 5 is H, the width is W, the length L ₁ of the fin 3 and the area of the base of the _first heat radiation part A ₁ are S ₁ , FIG. 1 and FIG. Referring to the surface area of the (base + standing wall-shaped fins) per base unit area in the first heat radiation member _{a 1 is, {(S 1 + 2 ×} H × L 1 × 9 + W × H × 9) / S 1} It becomes. H × L ₁ is the area of the side surfaces 3S and 5S of the fin, and is 2 because it is on both sides, and W × H is the area of the end surfaces 3E and 5E. Moreover, since nine fins 3 and 5 are arrange | positioned in the 1st thermal radiation part in total, 9 takes. If the area of the base of the second heat radiating part A ₂ is S ₂ and the length of the region is L ₂ , the same estimation is performed, {(S ₂ + 2 × H × L ₂ × 5 + W × H × 5) / S ₂ }. Since only the fins 3 are disposed, the number of fins 5 is applied to the area of the side surface and the end surface. For convenience of comparison, for example, the area S ₂ of the second base portion of the heat radiating portion _{A 2} equal to _S 1 (= _S), if taking equal length _{L 2} of the region in _L 1 (= _L) It becomes as follows. Needless to compare with formula, per base unit area, the surface area of the base and the fins, but rather the first heat radiation member A ₁ is greater than the second heat radiating portion A _2, how much greater the formula such as The degree of can be clarified.
<Surface area of (base + fin) per base unit area>
First radiating portion _{A 1: {1+ (18H ×} L + 9W × H) / S}
Second heat radiation part A ₂ : {1+ (10H × L + 5W × H) / S}
In the above description, the number of fins 3 is set to five and the number of fins 5 is set to four based on the illustration of FIG. 1, but the number of fins 3 or 5 is not limited to this.

The surface area of the base and the fin per unit area of the base is not strictly proportional to the temperature of the fluid in the heat radiating portion or the amount of heat radiated, but the temperature of the fluid in the heat radiating portion is high or low, or The amount of heat release can be used as a rough reference. In the heat dissipation structure 10 described above, the heights of the fins 3 and 5 are exemplified. However, the fins may be unevenly wide. In particular, when the heat radiation amount per base unit area of the first heat radiating portion A ₁ is made larger than that of the second heat radiating portion A ₂ , the fins of the _first heat radiating portion A ₁ are considered in terms of manufacturing ease. The height of all or part of the height may be higher than the height of the fins of the _second heat radiation part A2. When the heights of the fins are not uniform, the size of the surface area of the fins and the base and the amount of heat radiation of the heat radiating portion or the size of the fluid temperature may not agree with each other. Basically, the amount of heat radiation per unit area in the heat radiating part needs to be large or small, and the surface area of the fin and the base and the amount of heat radiation of the heat radiating part or the fluid temperature are normal (fin height It may be reversed from the case of the same size).

  The heat dissipation structure 10 can integrally form the base 1 and the fins 3 and 5 by extruding aluminum, aluminum alloy, copper, copper alloy, or the like. Further, the fins 3 and 5 may be attached on the base 1 by soldering, welding, welding, adhesion, or the like, or the fin length in the base parallel direction may be shortened by machining. In the present invention, ensuring surface contact between the base and the fin is important for ensuring good heat conduction.

What kind of fluid driving force is generated when the heat dissipation structure 10 is used will be described later. In FIG. 3, the fluid flow path 21 is disposed between the casing 23 and the base 1 so as to intersect in the direction of gravity, and the heat dissipation structure 10 is placed flat along the flow path 21. FIG. In FIG. 3, an object to be cooled, for example, a semiconductor device 15 is arranged over the back surface of the base 1. The semiconductor device 15 generates heat, and the heat is radiated from the fins 3 and 5 to the fluid through the base 1. In the portion of the first boundary of the heat radiating portion A ₁ and the second heat radiating unit A _2, the fluid temperatures T ₁ in the first heat radiating unit A ₁ is higher than the fluid temperature T ₂ in the second heat radiating portion A ₂ . Since the flow path 21 that is bounded by the housing wall 23, the fluid in the first heat radiation member A ₁ that is a high temperature, pressure than the fluid in the second heat radiating portion A ₂ is increased, the relative fluid driving force directed from the first heat radiating portion a ₁ in the second heat radiating portion a ₂ acts.

  The driving force naturally occurs between the fluid in the heat dissipation structure close to the flow path inlet and the fluid in the flow path, but the area of the base 1 or the area of the heat dissipation structure is to some extent as compared to the cross section of the flow path. In the case where the width is wide, when the temperature distribution is almost uniform within the range of the base portion 1, the driving force for circulating the fluid in the base portion 1 of the heat dissipation structure 10 is only small. However, as described above, when a region with a small heat dissipation amount and a large region are located next to each other within the range of the base 1 of the wide heat dissipation structure 10, a pressure level is generated between them, and a driving force is exerted on the fluid. Is generated. As a result, it is possible to obtain a driving force for circulating the fluid within the range of the base portion 1 of the heat dissipation structure 10 without disposing a forced circulation fan, and to increase the energy efficiency in heat dissipation.

4, the heat dissipating structure 10 is horizontally arranged in the same manner as in FIG. 3, but the fluid flow path 21 is open or a space with a height corresponding to the distance from the surface of the base 1 is large. It is explanatory drawing of the driving force produced in the case of a flow path. In this case, the first from the heat radiating portion A ₁ and the direction of gravity upward flow occurs in the opposite, second of the upward flow from the heat radiating portion A ₂ is a low-temperature portion of the temperature T ₂ is a high temperature portion of the temperature T ₁ of A flow occurs along the surface of the base where the fluid is replenished. For this reason, even if it does not operate a fan or a pump, circulation occurs naturally within the range of the heat dissipation structure 10, the heat dissipation amount can be improved, and the heat dissipation amount can be improved efficiently.

5, the base 1 of the heat dissipation structure 10 along the direction of gravity, is an explanatory diagram in the case of vertically arranged first heat radiating portion A ₁ above. When the heat dissipating structure 10 is vertically arranged as shown in FIG. 5, the first and second heat dissipating parts A ₁ and A ₂ do not require a difference in the heat dissipating amount per base unit area. The fluid that has reached the upper heat radiating part (first heat radiating part A ₁ ) via the heat radiating part (second heat radiating part A ₂ ) has already exchanged heat in the lower heat radiating part and transfers heat. Therefore, a temperature difference of high temperature on the upper side and lower temperature on the lower side naturally occurs. For this reason, like the subject in patent document 2, the amount of heat radiation in the upper heat radiating portion may be reduced, and the operation of the upper semiconductor device 15 may be hindered. In order to solve such a problem, for example, in Patent Document 2, a plurality of base portions having fins are arranged so that the interval between the lower base portions is wider than the upper portion, that is, the base gap in the upper portion is made smaller. Thus, measures are taken to increase the heat dissipation per unit area of the base at the top.

  The heat dissipation structure 10 shown in FIG. 5 is not a base composed of a plurality of layers but a heat dissipation structure including a single base and a fin standing on the base, so that the heat dissipation amount is increased at the top of the fin structure. As a result, similar to the contents disclosed in Patent Document 2, the same amount of heat radiation can be secured at the upper part as at the lower part. That is, in FIG. 5, since the heat dissipation amount per base unit area in the upper heat dissipation portion is larger than that in the lower heat dissipation portion, the heat dissipation amount in the upper heat dissipation portion is greatly reduced compared to the lower portion. Instead, the semiconductor device 15 located on the back surface of the upper heat radiating portion can dissipate its heat at the same rate as the lower heat radiating portion, and thus prevent an increase in temperature.

  The above description of the configuration shown in FIG. 5 is valid even when the flow path is open and wide, or when the flow path is narrowly defined by a housing (not shown). However, when the flow path is open, in the arrangement shown in FIG. 5, a replenishment flow driving force f is further generated, and the fluid is drawn into the upper heat radiating portion from the flow path having a relatively small temperature rise. . For this reason, a relatively low-temperature fluid is added to the upper heat radiating section, and the amount of heat radiated can be more reliably ensured.

Figure 6 is a case where the vertically arranged heat dissipation structure 10 similar to FIG. 5, the first heat radiation member A ₁ is larger heat radiation at the bottom, also heat dissipation it is smaller than the second radiating portion A ₂ is different in that it is arranged at the top. In this case, the heat radiation amount per base unit area in the lower part of the heat radiating portion A ₁ is greater than that in the upper portion of the heat radiating portion A _2, acts a force F pushing up the fluid from below. For this reason, the upward flow velocity of the fluid in the upper heat radiating portion A ₂ is accelerated, and in the upper heat radiating portion A ₂ , compared to the case where there is no difference in the heat radiating amount per base unit area (when the heat radiating amount is uniform), Heat dissipation per base unit area is accelerated. As a result, as shown in FIG. 6, even when the amount of heat radiation per base unit area of greater arranged at the lower side, the temperature rise of the semiconductor device 15 located on the back surface of the upper portion of the heat radiating portion A ₂ are uniform heat radiation amount distribution It is suppressed more than the case.

  In the case of the vertical arrangement of the heat dissipating structure in FIGS. 5 and 6, the above-described operational effect obtained by the presence of a region having a difference in the amount of heat radiation is the operational effect obtained in the horizontal arrangement of FIGS. 3 and 4. Is based on the same reason. That is, both are caused by the fact that a driving force for driving a fluid is generated within the range of the heat dissipation structure 10 due to the adjacent regions having different heat dissipation density.

  As described above, due to the difference in the density of the heat dissipation amount of the heat dissipation structure 10, a driving force is generated for the fluid, and in addition to the action of naturally generating a circulation force, The effect that the flow is easily turbulent can be obtained. That is, in the heat dissipating structure 10 shown in FIGS. 1 and 2, since the fins 3 and 5 are sparsely arranged, the fluid flows between the high density arrangement area of the fins and the low density arrangement area. When passing through, what has been in a laminar flow state is likely to be turbulent. It is the same whether the fluid moves from the sparse fin arrangement area to the fin sparse arrangement area or from the fin dense arrangement area to the sparse fin arrangement area. Easy to convert. As is well known, heat removal from a heat radiating part due to fluid (heat radiation) is much larger than laminar flow because turbulent flow separates the flow that forms a low-velocity layer on the solid surface and replaces it with new fluid. It is.

In summary, the driving force generated in the base region by the heat radiating structure 10 shown in FIG. 1 and FIG. 2 determines the heat radiation amount per unit unit area of the first heat radiating portion A ₁ and the second heat radiating portion A. _In order to make it different from _2, it is obtained as a result of changing the arrangement density of the fins. Furthermore, in addition to the factor of the density difference of the said heat dissipation amount, said heat dissipation structure 10 can contribute to the improvement of an effective heat dissipation from a turbulent flow generation factor.

(Embodiment 2)
FIG. 7 is a perspective view showing the heat dissipation structure 10 according to Embodiment 2 of the present invention. The heat dissipation structure 10 includes a base 1 and rod-like fins 7 standing on the base 1. The flow path through which the fluid in contact with the base 10 and the fins 7 may be formed in any manner as long as the fluid contacts the base and the fins, and is appropriately set according to the device in which the heat dissipation structure 10 is disposed. can do.

In the heat dissipation structure 10 of this embodiment, the fins 7 of the rod-shaped in the first heat radiation member A _1, densely than the second heat radiating portion A _2, are arranged at a density of approximately doubled. Therefore, the surface area of the (base + rod-like fins) per base unit area in the first heat radiation member A _1, from the surface area of the (base + rod-like fins) per base unit area in the second heat radiating portion A ₂ growing.

  The surface area of the base and the fin per unit area of the base is not strictly proportional to the temperature of the fluid in the heat radiating portion or the amount of heat radiated, but the temperature of the fluid in the heat radiating portion is high or low, or The amount of heat release can be used as a rough reference. In the heat dissipation structure 10 described above, the fins 7 have the same height. However, the fins may be unevenly wide. When the heights of the fins are uneven, the size of the surface area of the fin and the base and the amount of heat radiation of the heat radiating portion or the size of the fluid temperature may not be consistent, but the technical idea of the present invention Basically, the amount of heat radiation per unit area in the heat radiating part may be large or small, and the size of the surface area of the fin and the base and the amount of heat radiation of the heat radiating part or the size of the fluid temperature are normal (fin height It ’s okay if the trend is reversed.

  In the heat dissipation structure 10, the base 1 and the fins 7 can be integrally formed by using a friction press that is a kind of cold forging of aluminum, aluminum alloy, copper, copper alloy, or the like. According to this flexure press, apart from the flat type fins, the heat radiation of the base and the fins, usually with a pin diameter of 1 mm to 5 mm, a pin height of 5 mm to 10 mm, a pin pitch of 1 mm to 5 mm, and a base thickness of 2 mm to 4 mm. The structure can be integrally molded in the cold.

In FIG. 8, the fluid flow path 21 is disposed between the casing 23 and the base portion 1 so as to intersect in the direction of gravity, and the heat dissipation structure 10 is laid flat along the flow path 21. FIG. In FIG. 8, an object to be cooled, for example, a semiconductor device 15 is arranged over the back surface of the base 1. The semiconductor device 15 generates heat, and the heat is radiated from the fins 7 to the fluid through the base 1. In the portion of the first border of the heat radiating portion A ₁ and the second heat radiating unit A _2, the fluid temperatures T ₁ in the first heat radiating unit A ₁ is higher than the fluid temperature T ₂ in the second heat radiating portion A ₂ . Since the flow path 21 that is bounded by the housing wall 23, the fluid in the first heat radiation member A ₁ that is a high temperature, pressure than the fluid in the second heat radiating portion A ₂ is increased, the relative fluid driving force directed from the first heat radiating portion a ₁ in the second heat radiating portion a ₂ acts.

  The driving force naturally occurs between the fluid in the heat dissipation structure close to the flow path inlet and the fluid in the flow path, but the area of the base 1 or the area of the heat dissipation structure is to some extent as compared to the cross section of the flow path. In the case where the width is wide, if the temperature distribution is almost uniform within the range of the base 1, the driving force for circulating the fluid within the range of the base 1 of the heat dissipation structure 10 is limited and only small. However, as described above, when a region with a small amount of heat dissipation and a large region are located next to each other within the range of the base portion 1 of the wide heat dissipation structure 10, a pressure level is generated between them. A driving force is generated for the fluid. As a result, it is possible to obtain a driving force for circulating the fluid within the range of the base portion 1 of the heat dissipation structure 10 without disposing a forced circulation fan, and to increase the energy efficiency in heat dissipation.

9, the heat dissipating structure 10 is horizontally arranged in the same manner as in FIG. 8, but the fluid flow path 21 is open, or a space having a height corresponding to the distance from the surface of the base 1 is large. It is explanatory drawing of the driving force produced in the case of a flow path. In such a case, the first from the heat radiating portion A ₁ and the direction of gravity upward flow occurs in the opposite, second of the upward flow from the heat radiating portion A ₂ is a low-temperature portion of the temperature T ₂ is a high temperature portion of the temperature T ₁ of A horizontal flow is created that replenishes the fluid. For this reason, even if it does not operate a fan or a pump, circulation occurs naturally within the range of the heat dissipation structure 10, the heat dissipation amount can be improved, and the heat dissipation amount can be improved efficiently.

10, a base 1 of the heat dissipation structure 10 along the direction of gravity, is an explanatory diagram in the case of vertically arranged first heat radiating portion A ₁ above. When the heat dissipating structure 10 is arranged vertically as shown in FIG. 10, the first and second heat dissipating parts A ₁ and A ₂ do not require a difference in the amount of heat dissipated per base unit area. The fluid that has reached the upper heat radiating part (first heat radiating part A ₁ ) via the heat radiating part (second heat radiating part A ₂ ) has already exchanged heat in the lower heat radiating part and transfers heat. Therefore, a temperature difference of high temperature on the upper side and lower temperature on the lower side naturally occurs. For this reason, the heat radiation amount in the upper heat radiation portion may be reduced, which may hinder the operation of the upper semiconductor device 15. In order to solve such a problem, for example, in Patent Document 2, a plurality of base portions having fins are arranged so that the interval between the lower base portions is wider than the upper portion, that is, the base gap in the upper portion is made smaller. Thus, measures are taken to increase the heat dissipation per unit area of the base at the top.

  The heat dissipation structure 10 shown in FIG. 10 is not a base composed of a plurality of layers but a heat dissipation structure including a single base and fins 7 standing on the base, so that the heat dissipation amount is increased at the top of the fin structure. As a result, similarly to the content disclosed in Patent Document 2, the same amount of heat radiation can be secured at the upper part as at the lower part. That is, in FIG. 10, since the heat dissipation amount per base unit area in the upper heat dissipation portion is larger than that in the lower heat dissipation portion, the heat dissipation amount in the upper heat dissipation portion is greatly reduced compared to the lower portion. Instead, the semiconductor device 15 located on the back surface of the upper heat radiating portion can dissipate its heat at the same rate as the lower heat radiating portion, and thus prevent an increase in temperature.

  The above description of the configuration of FIG. 10 is valid even when the flow path is open and wide, or when the flow path is narrowly defined by a housing (not shown). However, when the flow path is open, in the arrangement shown in FIG. 10, a replenishment flow driving force f is further generated, and the fluid is drawn into the upper heat radiating portion from the flow path in a range where the temperature rise is relatively small. . For this reason, a relatively low-temperature fluid is added to the upper heat radiating section, and the amount of heat radiated can be more reliably ensured.

Figure 11 is a case where the vertically arranged heat dissipation structure 10 similar to FIG. 10, the first heat radiation member A ₁ is larger heat radiation at the bottom, also the heat radiation amount is smaller than it the second heat radiating portion A ₂ is different in that it is arranged at the top. In this case, the heat radiation amount per base unit area in the lower part of the heat radiating portion A ₁ is greater than that in the upper portion of the heat radiating portion A _2, acts a force F pushing up the fluid from below. For this reason, the upward flow velocity of the fluid in the upper heat radiating portion A ₂ is accelerated, and in the upper heat radiating portion A ₂ , compared to the case where there is no difference in the heat radiating amount per base unit area (when the heat radiating amount is uniform), Heat dissipation per base unit area is accelerated. As a result, as shown in FIG. 11, even when the amount of heat radiation per base unit area of greater arranged at the lower side, the temperature rise of the semiconductor device 15 located on the back surface of the upper portion of the heat radiating portion A ₂ are uniform heat radiation amount distribution It is suppressed more than the case.

  In the case of the vertical arrangement of the heat dissipating structure of FIGS. 10 and 11, the above-described operational effect obtained by the presence of a region having a difference in the amount of heat radiation is the operational effect obtained in the horizontal arrangement of FIGS. Is based on the same reason. That is, both are caused by the fact that a driving force for driving a fluid is generated within the range of the heat dissipation structure 10 due to the adjacent regions having different heat dissipation density.

  As described above, due to the difference in the density of the heat dissipation amount of the heat dissipation structure 10, a driving force is generated for the fluid, and in addition to the action of naturally generating a circulation force, the fluid flow is likely to be turbulent. An effect can be obtained. That is, in the heat dissipating structure 10 shown in FIG. 7, since the fins 7 are densely arranged, the fluid passes between the high density arrangement area of the fins and the low density arrangement area. What was previously in a laminar flow state is likely to be turbulent. It is the same whether the fluid moves from a sparse arrangement to a dense arrangement or from a dense arrangement to a sparse arrangement, and in either case, the fluid tends to be turbulent. It is known that the heat removal from the heat dissipation part (heat dissipation) by the fluid is much larger than the laminar flow because the turbulent flow separates the flow that forms a layer with a low flow velocity on the solid surface and replaces it with a new fluid. . Even if the rod-like fins 7 are arranged in parallel along the flow direction of the fluid, even if they are arranged in a zigzag manner that is much easier to turbulent than the parallel arrangement, the turbulent flow caused by the dense arrangement of the fins The effect of promoting generation remains unchanged.

In summary, the driving amount in the base region by heat dissipation structure 10 shown in FIG. 7, the heat radiation amount per base unit area the first heat radiation member A ₁ and the second heat radiating portion A ₂ in a different manner In order to achieve this, it is obtained as a result of varying the fin arrangement density. Furthermore, in addition to the factor of the density difference of the said heat dissipation amount, said heat dissipation structure 10 can contribute to the improvement of an effective heat dissipation from a turbulent flow generation factor.

(Embodiment 3) -Distribution of heat dissipation amount (surface area of fin and base) per base unit area-
The heat dissipation amount per base unit area, or the distribution of the fin and base surface area per base unit area may be any form, for example, as shown in FIG. It may be a form that changes stepwise. As can be seen from the way of the first heat radiation member A ₁ and the second heat radiation member A ₂ set at 12, the heat radiation amount per base unit area of the first heat radiation member A ₁ and the second heat radiation member greater than that of a _2, it may be divided how these heat radiating portion. In addition, within the range of the heat dissipation structure, a heat dissipation amount per unit area of the substrate that is intermediate between the first heat dissipation portion and the second heat dissipation portion, or higher than any of these, or lower than any of these. There may be other areas to have.

In the first and second embodiments of the present invention, the area of the heat dissipation structure is illustrated an embodiment which is divided into two by the first heat radiation member A ₁ and the second and the heat radiating portion A _2. However, in the present invention, as shown in FIG. 13, for example, a pattern in which the first heat radiating portion A ₁ and the second heat radiating portion A ₂ are alternately arranged may be used. Or, although not shown, in the present invention, the first heat radiation member A ₁ of the rectangle and the second heat radiating portion A ₂ may be a pattern arrayed in a checkered pattern.

  Although the embodiments and examples of the present invention have been described above, the embodiments and examples of the present invention disclosed above are merely examples, and the scope of the present invention is the implementation of these inventions. It is not limited to the form. The scope of the present invention is indicated by the description of the scope of claims, and further includes meanings equivalent to the description of the scope of claims and all modifications within the scope.

  In the cooling structure of the present invention, it is possible to apply a driving force to the fluid located in the heat dissipation structure by making a difference in heat dissipation density between adjacent heat dissipation portions, and without using a fan or the like, Therefore, a high level of heat dissipation can be realized with high energy efficiency.

It is a perspective view of the thermal radiation structure in Embodiment 1 of this invention. It is a top view of the thermal radiation structure of FIG. It is sectional drawing which shows the state which has arrange | positioned the thermal radiation structure of FIG. 1 in the horizontal narrow flow path. It is sectional drawing which shows the state which has arrange | positioned the thermal radiation structure of FIG. 1 to the horizontal open flow path or the flow path of large height space. It is sectional drawing which shows the state which has arrange | positioned the thermal radiation structure of FIG. It is sectional drawing which shows the state which has arrange | positioned the thermal radiation structure of FIG. 1 in the vertical flow path with the high thermal radiation part as the lower part. It is a perspective view of the thermal radiation structure in Embodiment 2 of this invention. It is sectional drawing which shows the state which has arrange | positioned the thermal radiation structure of FIG. 7 to the horizontal narrow flow path. It is sectional drawing which shows the state which has arrange | positioned the thermal radiation structure of FIG. 7 in the horizontal open flow path or the flow path of large height space. It is sectional drawing which shows the state which has arrange | positioned the thermal radiation structure of FIG. It is sectional drawing which shows the state which has arrange | positioned the thermal radiation structure of FIG. It is a figure which illustrates the heat dissipation amount per base unit area in Embodiment 3 of this invention, or the distribution form of the said surface area. It is a figure which illustrates the heat dissipation amount per base unit area, or the distribution pattern of the said surface area.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Base part, 3, 5 Standing-wall-like fin, 7 Rod-like fin, 10 Heat dissipation structure, 15 Semiconductor device, 21 Flow path, 26 Case, A ₁ 1st heat dissipation part (high heat dissipation part), A ₂ 2nd Heat dissipation part (low heat dissipation part).

Claims (4)

The base,
A first heat dissipating part located in the first region of the base and dissipating heat;
A second heat dissipating part located in a second region adjacent to the first region to dissipate heat;
A heat dissipation structure characterized in that a heat dissipation amount per base unit area in the first heat dissipation portion is larger than a heat dissipation amount per base unit area in the second heat dissipation portion. The base,
A first heat dissipating part having fins standing in the first region of the base part;
A second heat dissipating part having fins standing in a second region adjacent to the first region in the base;
A heat radiating structure characterized in that the surface area of the fins and the base portion per base unit area in the first heat radiating portion is larger than the surface area of the fins and the base portion per base unit area in the second heat radiating portion.   The heat dissipation structure according to claim 2, wherein a fin height of the first heat dissipation portion and a fin height of the second heat dissipation portion are aligned.   3. The heat dissipation structure according to claim 2, wherein a fin height of all and a part of the fins of the first heat dissipation portion is higher than a fin height of the second heat dissipation portion.

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