JP2018148187A - Heat sink - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat sink that can evenly cool down regardless of the position of a heat source on a substrate.SOLUTION: A heat sink 8 includes a base part 12 contacting an electronic element 10 and a fin part 13 composed of a plurality of fins 14 and 14a, and the fin distance on the downstream side is narrower than the fin distance on the upstream side in the flowing direction F with respect to an electronic element 10 (L)' which is a specific heat source. On the upstream side of the specific heat generation source, air passes between the fins arranged at a relatively large first interval and cools the heat generation source with a corresponding heat radiation power. On the downstream side of the specific heat source, the resistance of the circulating air is large and the heat radiation power is high. The temperature gradient occurring on the upstream side and the downstream side of the specific heat generation source becomes as small as possible and the temperature of the entire heat generation source can be made more uniform than the previous temperature, and the heat generation source hardly exceeds the allowable temperature at the time of use.SELECTED DRAWING: Figure 4

Description

  The present invention relates to a heat sink in which a base portion provided with a fin portion is brought into contact with a plurality of heat sources and heat is dissipated by air flowing through the fin portions to cool the heat source, and in particular, the heat source is upstream of the air. It is related with the heat sink which can cool equally regardless of whether it exists in the side or the downstream.

  An electronic device configured to have a plurality of electronic elements mounted on a substrate and exhibit a certain function is referred to as a module or a unit or the like, and is used alone or as a component in various electronic devices. Incorporated and used. In such a unit, since the electronic element generates heat during use, it is necessary to take care so that the temperature of the electronic element does not exceed the allowable temperature for use by effectively dissipating this heat. An invention for cooling a semiconductor module which is an example of such a unit is disclosed in Patent Document 1 below.

  The invention disclosed in Patent Document 1 below relates to a motor control device that cools a semiconductor module with a heat sink. The motor control device of the present invention is in close contact with the heat sink 1 and the heat sink 1 provided with the fin 12 provided on the base portion 11, the fin 12 of the heat sink 1, the fan 3 that cools the heat sink 1, and the heat sink 1. And a semiconductor module. According to the heat sink 1, the wide pitch portion 123 having a wide fin interval is provided in a portion of the fin 12 facing the fan 3.

  If the gap between the heat sink and the fan is made too small, there is a problem that the cooling air from the fan does not flow between the fins of the heat sink. However, according to the heat sink of the present invention, the pitch of the fins of the heat sink Therefore, the cooling air from the fan can flow smoothly between the fins. Thereby, the air volume of the cooling air flowing between the fins can be increased, the heat sink cooling performance can be improved, and the entire motor control device can be miniaturized.

JP 2008-177314 A

  When a unit having a plurality of electronic elements mounted on a substrate is cooled by a heat sink as described above, the base portion of the heat sink is brought into contact with the plurality of electronic elements on the substrate and air is circulated along the fins. Thus, the heat conducted from the plurality of electronic elements to the base portion is dissipated into the air by the fins.

  However, when the number of electronic elements mounted on the substrate of the unit is large and the calorific value is large, or a plurality of electronic elements having a large calorific value are arranged side by side from the upstream side to the downstream side along the air flow direction. In such a case, the upstream side in the air flow direction is easily cooled, but the downstream side is more difficult to cool because the air temperature rises, so the substrate temperature increases from upstream to downstream. An increasing temperature gradient is generated, and it is difficult to make the temperature of the entire substrate uniform.

  As described above, the heat sink in the invention described in Patent Document 1 is characterized in that the cooling air from the fan smoothly flows between the fins to improve the cooling performance of the heat sink. Cooling conditions on the downstream side compared to the upstream side, such as when there is a large number of and the overall heat generation amount is large, or when electronic elements with a large heat generation amount are arranged side by side from the upstream side to the downstream side However, an effective cooling effect could not be expected under severe conditions.

  FIG. 7 is a front view showing a heat sink 101 of a comparative example provided on the front side of the substrate 100 on which a plurality of electronic elements are mounted, and the temperature of the heat sink 101 when using the electronic elements is determined using software. It is calculated by simulation and is represented by a contour superimposed on the drawing of the heat sink 101. The unit of this comparative example is not covered with a duct.

  The heat sink 101 includes a plate-like base portion 102 and fin portions 103 provided on the base portion 102. The fin portion 103 has a longitudinal shape along the left-right direction in the drawing, which is the air flow direction, and is composed of a plurality of fins arranged at predetermined intervals in the vertical direction perpendicular to the longitudinal direction. In the unit, an electronic element (not shown), which is a heat source, is disposed on a substrate 100 that is slightly larger than the base portion 102 of the heat sink 101, but the electronic element that generates particularly large heat is along the air flow direction. Are provided at three positions at substantially equal intervals. The heat sink 101 has the base portion 102 in contact with the electronic elements of the unit. When air flows through the fin portion 103 from the left side to the right side in the drawing, the heat is dissipated by the air and the unit is cooled.

  As can be seen from the contours in FIG. 7 and the temperature display in the figure, at three positions of the heat sink 101 along the air flow direction in the left-right direction in the figure, there are places A1, A2, A3 having higher temperatures than the surroundings. Appears. In FIG. 7, the approximate position is indicated by the intersection of two types of arrows in the vertical and horizontal directions. The temperatures of these portions A1, A2, and A3 are 74 to 75 ° C, 76 to 77 ° C, and 79 to 80 ° C, respectively. That is, the upstream side in the air flow direction is easy to cool, but the downstream side is more difficult to cool because the air temperature rises, so the temperature gradient in which the substrate temperature rises from upstream to downstream increases. As a result, the temperature of the entire heat sink cannot be lowered uniformly. In particular, the temperature at the most downstream position reaches 80 ° C., and there is a possibility that the allowable temperature at the time of use of the electronic element mounted on the unit may be exceeded.

  The present invention has been made in view of various problems in the conventional technology described above, and a base portion provided with a fin portion is brought into contact with a plurality of heat sources, and heat is dissipated by air flowing through the fin portion. Accordingly, an object of the present invention is to provide a heat sink that can cool evenly regardless of whether the heat source is on the upstream side or the downstream side of the air flow.

The heat sink 8 according to claim 1 is:
A base portion 12 that contacts a plurality of heat sources 10, 10 (L), 10 (L) ′ on an object to be attached, and a fin portion 13 that dissipates heat by air that is provided in the base portion 12 and circulates. , 13 (U), 13 (D),
The fin portions 13, 13 (U), 13 (D)
It is a longitudinal shape along the air flow direction F, and is composed of a plurality of fins 14 and 14a arranged at predetermined intervals in the width direction intersecting the longitudinal direction,
The first interval that is the interval between the fins 14 on the upstream side in the flow direction F is configured to be larger than the second interval that is the interval between the fins 14 and 14a on the downstream side in the flow direction F.
When the distance between the fins 14 and 14a is constant, the specific position where the specific heat source 10 (L) ′ that will exceed the allowable temperature at the time of attachment is disposed as a reference. The boundary between the first region S1 in which the interval is the first interval and the second region S2 in which the interval between the fins 14 and 14a is the second interval is set near the upstream side including immediately above the specific position. It is characterized by that.

The heat sink 8 according to claim 2 is the heat sink 8 according to claim 1,
The dimension in the width direction of the fin portions 13 and 13 (D) including the plurality of fins 14 and 14a disposed at the second interval is the plurality of fins 14 disposed at the first interval. It is characterized by being larger than the dimension in the width direction of the fin portions 13 and 13 (U).

  According to the heat sink described in claim 1, the air flowing around the heat sink along the predetermined flow direction is arranged at a relatively wide first interval upstream of the specific position of the specific heat source. Passes between the fins and cools the heat source with a suitable heat dissipation. And in the downstream rather than the specific position of a specific heat generation source, air enters between the fins arrange | positioned by the 2nd space | interval narrower than an upstream. Between fins arranged at narrower second intervals, compared to the upstream side of the specific heat source having a wide fin interval, the resistance of the flowing air is increased, and the fins are sufficiently exposed to air, and the heat dissipation power is increased. As a result, the temperature gradient generated on the upstream side and downstream side of the air with the specific position of the specific heat source as the boundary becomes as small as possible, and the temperature of the heat source as a whole can be made uniform compared to the conventional case. The risk that the heat source including the specific heat source will exceed the allowable temperature during use can be avoided.

  According to the heat sink described in claim 2, in the fin portion on the upstream side where the fin interval is wide and in the vicinity thereof, the resistance of the air flowing between the fins is larger than the resistance of the air flowing along the outer space of the fin portion. Since the resistance is smaller, a lot of air enters the space. And the heat which the air which distribute | circulates along the said space receives from the fin which exists only on one side is less than the heat which the air which distribute | circulates between the fins of an upstream fin part receives from the fin on both sides. In this way, air from the space having a low temperature and a high flow rate as compared with the air coming out from the upstream fins having a wide interval enters between the fins having a narrow interval downstream. For this reason, air having a relatively low temperature flows between the fins with a large resistance and sufficiently hits the fins to obtain a high heat radiating power. Therefore, a particularly strong cooling effect is obtained at both end portions in the width direction of the downstream fin portion.

It is a perspective view which shows the state which removed the top plate of the housing | casing so that the inside of the electronic device which concerns on 1st Embodiment can be seen. It is a perspective view of the unit with which the electronic device concerning a 1st embodiment is equipped. It is a front view which shows the state which removed the duct from the unit in 1st Embodiment. It is a diffusion exploded perspective view of a unit with which an electronic device concerning a 1st embodiment is equipped. It is a front view of the unit with which the electronic device concerning a 1st embodiment is equipped, and is the figure which expressed the temperature of the heat sink at the time of use of the unit especially on the heat sink in the contour. When the electronic apparatus according to the first embodiment is used, a graph showing the relationship of the junction temperature (vertical axis) with respect to the positions (horizontal axis) of a plurality of heat sources provided in the unit, and the gap between the fins under the same conditions It is the table | surface which showed the graph which shows the same relationship by the heat sink of the comparative example which is constant in the same figure. It is a front view of the unit of the comparative example with which an electronic device is mounted | worn, Comprising: The temperature at the time of use of the heat sink of the comparative example with the constant space | interval of a fin is a figure which accumulated on the heat sink and represented with the contour.

  The electronic device 1 according to the first embodiment will be described with reference to FIGS. The type of the electronic device 1 to which the heat sink of the present invention is applied is not limited to a specific type, but in this embodiment, as an example of the electronic device 1, as shown in FIG. 1, a radio that is an inspection device for a mobile terminal A communication analyzer was cited. A radio communication analyzer is a device that demonstrates the functions of a base station for each standard of a variety of mobile terminal communication methods. By inserting a unit created according to the required function into a slot, Perform an inspection.

  As shown in FIG. 1, a frame 4 that is a frame-like structure for attaching a unit 3 that is an electronic device is attached to the inside of a housing 2 of the electronic apparatus 1. A plurality of thin plate-like units 3 and 3a can be inserted into the inside of the frame 4 from the upper opening of the frame 4, and the units 3 and 3a are mutually spaced apart from each other within the frame 4. It is configured to be arranged side by side in a substantially parallel state. In the example shown in FIG. 1, seven slots in which the units 3 and 3a are inserted are provided in the frame 4, and two of the seven units 3 and 3a mounted have the heat sink of the present invention. 3 (see FIG. 2), and the other five are other types of units 3a.

  As shown in FIG. 1, two suction fans 5 are provided on the right side surface of the housing 2 of the electronic device, and along the surface of the thin unit 3 provided inside the frame 4, In the figure, cooling air is circulated along the flow direction F from the upstream on the left side toward the downstream side on the right side. Further, the left side surface of the housing 2 that hits the upstream side of the circulating air has an air permeable structure so that the air drawn by the suction fan 5 enters the housing 2. In addition, on the front surface of the housing 2, an operation unit and a display device of a radio communication analyzer which is an electronic device are provided.

  FIG. 2 is a perspective view of the unit 3 according to the embodiment having the heat sink of the present invention. As will be described later, the unit 3 according to the embodiment includes a substrate 6 on which an electronic element is mounted and a cooling device 7 that cools the electronic element. The cooling device 7 includes a heat sink 8 and a duct 9. ing. FIG. 3 is a front view showing the heat sink 8 inside after removing the duct 9 on the front side of FIG. Then, the heat sink 8 on the front side in FIG. 3 is removed from the back substrate 6 and the duct 9 is shown in the diffusion exploded perspective view of FIG.

  A plurality of electronic elements 10 serving as heat generation sources are mounted on the upper surface of the substrate 6 shown in FIGS. 2 to 4 as shown in FIG. Although the kind and function of the electronic element 10 are not ask | required, all generate | occur | produce heat at the time of use. In particular, at the three positions set at equal intervals on the substrate 6 along the air flow direction F, the same type of electronic element 10 (L) having a larger calorific value than the other electronic elements 10 is respectively provided. It is attached. A connector 11 for connecting the unit 3 to the electronic device 1 when the unit 3 is mounted in the slot is provided on the lower edge of the substrate 6.

  As shown in FIGS. 2 to 4, a heat sink 8 is provided so as to contact the electronic element 10 on the substrate 6. The heat sink 8 is a member that constitutes the cooling device 7 for the electronic element 10 together with the duct 9 described later. As shown in FIGS. 3 and 4, the heat sink 8 has a rectangular base portion 12 that is substantially the same shape as the substrate 6 and slightly smaller than the substrate 6, and a fin portion 13 provided on the front side of the base portion 12. . Although not shown, a shallow concave portion corresponding to the outer shape of the electronic element 10 (L) is formed in a portion corresponding to the tallest electronic element 10 on the back side (substrate 6 side) of the base portion 12. . This is to unify the thickness of the electronic element 10 (L) and the base portion 12 to a value as thin as possible when they are bonded together with a heat conduction putty. Further, the fin portion 13 is a plate material having a longitudinal shape along the air flow direction F, and includes a plurality of fins 14 arranged at predetermined intervals (also referred to as pitch) in a direction intersecting the longitudinal direction. Has been. The fins 14 are parallel to the longitudinal direction of the base portion 12 and the air flow direction F. In the present embodiment, the direction in the plane of the base portion 12 and perpendicular to the longitudinal direction of the base portion 12 or the fin 14 (the short direction of the base portion 12) is referred to as the width direction of the fin portion 13. .

  As shown in FIGS. 3 and 4, if the interval between the fins 14 on the upstream side in the flow direction F is called a first interval and the interval between the fins 14 on the downstream side in the flow direction F is called a second interval, The first interval is approximately twice the second interval. That is, on the downstream side in the flow direction F, the fins 14 are also provided at positions between the fins 14 on the upstream side in the flow direction F, and the number of fins 14 on the upstream side in the flow direction F is upstream. This is approximately twice the number of fins 14 on the side.

  As shown in FIG. 4, the heat generation amount is particularly large among the electron sources 10, and among the three electronic elements 10 (L) arranged on the substrate 6 along the flow direction F, the flow direction F The most downstream electronic element 10 (L) is called a specific heat source, and its position is called a specific position. The electronic element 10 (L), which is a specific heat source, is particularly indicated by reference numeral 10 (L) ′. When this specific position is used as a reference, the upstream side of the specific position in the flow direction F is the first region S1 in which the interval between the fins 14 is the first interval. Similarly, the downstream side of the specific position in the flow direction F is the second region S2 in which the interval between the fins 14 is the second interval. In other words, the boundary between the upstream first region S1 in which the gap between the fins 14 is wide and the downstream second region S2 in which the gap between the fins 14 is narrow is an edge 15 on the upstream side of the specific electronic element 10 (L) ′. It becomes.

  The specific position of the specific heat source that becomes the boundary between the intervals of the fins 14 is determined as follows. That is, if the interval between the fins 14 is constant over the entire length (for example, the first interval), as described in “Problems to be solved by the invention”, the upstream side in the air flow direction F is easily cooled. The downstream side is more difficult to be cooled because the air temperature rises. Therefore, as in the example described above with reference to FIG. 7, when the temperature of the heat sink 8 is measured when the electronic element 10 is used, the temperature increases as it goes downstream along the flow direction F. At any position, a high-temperature region that is extremely different from the surroundings appears. That is, a large temperature gradient is generated in which the temperature of the substrate 6 rapidly increases from upstream to downstream. In this way, the heat source corresponding to the position on the heat sink 8 where a region having a unique high temperature as compared with the surroundings is called a specific heat source, and in the present embodiment, the three electronic elements 10 (L ), The electronic element 10 (L) ′ located on the most downstream side corresponds to a specific heat source.

As described above, the position of the specific heat source that generates a large temperature gradient when the fin interval is constant (that is, the above-described specific position) may be determined, and the interval between the fins 14 may be narrower downstream. If it does in this way, the resistance of the air which distribute | circulates between fins will become large downstream from a specific heat generation source, air will fully hit the fin 14, and heat dissipation power will become high. As a result, the temperature gradient generated on the upstream side and downstream side of the air with the specific position of the specific heat source as a boundary becomes as small as possible, and the overall temperature of the substrate 6 having a plurality of heat sources is higher than the conventional temperature. It can be made uniform. As a result, it is possible to avoid the risk that the heat source including the specific heat source will exceed the allowable temperature during use. As the allowable temperature at which the electronic elements 10, 10 (L), 10 (L) ′ can be used without problems under predetermined conditions, various temperatures defined from various indices can be employed. Temperature (junction temperature) can be used.
The boundary between the first region S1 and the second region S2 is a position that matches the edge 15 of the specific electronic element 10 (L) ′, but is not limited thereto. Even if the boundary is set in the vicinity of the upstream side of the edge 15, an equivalent effect can be obtained.

  As shown in FIGS. 3 and 4, the widthwise dimension of the entire downstream fin portion 13 (D) arranged at the second interval is equal to the upstream fin portion 13 (U) arranged at the first interval. It is larger than the overall width dimension. That is, the downstream fin portion 13 (D) has two fins 14 a at two positions that are further outward than the outermost fin 14 in the width direction of the upstream fin portion 13 (U). It has further. In addition, as shown in FIG. 3, the two fins 14a on the upper side in the drawing are slightly longer than the two fins 14a on the lower side in the drawing in the fin portion 13 (D) on the downstream side.

  In addition, although the heat sink 8 demonstrated above is a product made from aluminum, in order to improve heat dissipation capability, it is preferable to employ | adopt the construction method which attaches the fin part 13 to the base part 12 by crimping rather than producing by aluminum material extrusion molding.

  1 to 4, a copper heat conduction member 16 is attached to the upper edge of the base portion 12 of the heat sink 8. As shown in FIG. 1, after inserting the unit 3a into each slot inside the housing 2, the opening on the top surface of the housing 2 is closed with an aluminum cover (lid body) 17 indicated by a two-dot chain line. If the bolt 18 is inserted from the hole formed at a predetermined position 17 and screwed into the screw hole of the heat conducting member 16 and fixed, the housing 2, the cover 17 and the unit 3 are fixed together. Accordingly, the heat absorbed by the heat sink 8 is dissipated by the fin portion 13 and is conducted from the heat conducting member 16 to the cover 17 to be dissipated.

  As shown in FIGS. 2 and 4, the unit 3 has a duct 9 that covers the heat sink 8. The duct 9 is a member that constitutes the cooling device 7 for the electronic element 10 together with the heat sink 8 described above. The duct 9 is a rectangular plate that is substantially the same shape as the base portion 12 of the heat sink 8 and is slightly larger than the base portion 12. An upper flange 9 a and a lower flange 9 b that surround the base portion 12 of the heat sink 8 are respectively provided on the upper edge and the lower edge of the duct 9. The lower flange 9 b covers the entire base portion 12. The upper flange 9 a covers substantially half of the downstream side of the base portion 12 except for the portion of the heat conducting member 16. The upstream side of the duct 9 in the flow direction F is an inlet 20, and air that is drawn by the suction fan 5 and flows into the duct 9. In the flow direction F, the downstream side of the duct 9 is an outlet 21, and the air circulated along the heat sink 8 flows out of the duct 9.

  As shown in FIGS. 2 and 4, the duct 9 is provided with an opening 30. The opening 30 is a vertically long rectangle, and its long side substantially matches the vertical dimension of the electronic element 10 (L) ′, which is a specific heat source, and its short side is substantially half of the horizontal dimension of the electronic element 10 (L) ′. It has become. The opening 30 is formed at a position corresponding to a specific position of the specific heat source. More specifically, the opening 30 is formed at a position where the upstream vertical edge 30a substantially coincides with the upstream edge 15 of the electronic element 10 (L) '. Therefore, when the air flowing outside the duct 9 enters the inside of the duct 9 through the opening 30, the air is supplied to the upstream side of the fins 14 having the narrow second interval, and the electronic element 10 (L) ′ as the specific heat source is efficiently used. Can be cooled.

  As shown in FIGS. 2 and 4, the inlet 20 of the duct 9 is wider than the outlet 21 by the enlarged portion 22. As shown in FIG. 2, the air flowing in the vicinity of and behind the heat conducting member 16 does not contribute to the cooling of the electronic elements 10, 10 (L), 10 (L) ′ by the heat sink 8. An enlarged portion 22 is provided on the upstream side, and air flowing through this position is guided into the duct 9 by the enlarged portion 22 and used for cooling.

  As shown in FIG. 3, in the fin portion 13 of the first region S1 having a wide interval, the space S3 between the upper and lower two fins 14 and the duct 9 in the outermost side in the width direction is the first region. It is wider than the interval between the fins 14 of S1. Accordingly, a large amount of air that has entered the duct 9 enters the space S3 having a low air resistance. Moreover, the heat which the air which distribute | circulates along the said space S3 receives from the fin 14 which exists only in one side is the fin 14 which the air which distribute | circulates between the fins 14 and 14 of the upstream fin part 13 (U) exists in both sides. , 14 less heat. Therefore, the cooling effect by the air entering the fins 14a and 14 having a narrow interval from the space S3 to the second region S2 is particularly great. That is, in the fins 14a, 14 having a narrow interval between the second regions S2, the resistance of the flowing air increases, the air sufficiently hits the fins 14a, 14, and the heat dissipation power increases, so that the width direction of the second region S2 increases. A particularly strong cooling effect is obtained at both ends (the upper and lower ends of the second region S2 in FIG. 3).

Next, effects of the above configuration will be described.
When the electronic apparatus 1 is used, the unit 3 housed therein generates heat, and therefore the suction fan 5 is driven to cool it. In FIG. 1, the air sucked by the suction fan 5 enters the housing 2 from the left side surface (left side in the figure) of the housing 2, passes between the units 3 and 3 a in the housing 2, and After cooling, the air is exhausted from the suction fan 5 on the right side surface (right side in the figure) of the housing 2 to the outside of the housing 2.

  Since air that has entered the housing 2 generally circulates in a place with a low resistance, if there is a slot in which the unit 3 is not inserted in FIG. Will flow into the slot. However, as shown in FIG. 1, when the unit 3 a having the duct 9 of the present embodiment and the other unit 3 without the duct 9 are arranged in the housing 2 without a gap, the unit 3 a is more than the other unit 3. The unit 3a of the embodiment in which the duct 9 forms a cylindrical air passage is easier to take in air.

  As shown in FIGS. 2 and 4, a sufficient amount of air taken in from the inlet 20 of the unit 3 having the enlarged portion 22 is upstream (first) from the electronic element 10 (L) ′ that is the specific heat source. In one region S1), the heat sources (electronic elements 10, 10 (L)) can be cooled by passing between the fins 14 arranged at a relatively wide first interval and exhibiting a corresponding heat radiation force. .

  On the downstream side (second region S2) from the specific position of the electronic element 10 (L) ′ that is the specific heat generation source, the air enters between the fins 14 arranged at the second interval narrower than the upstream side. The air supplied to the second region S2 is air that has been subjected to cooling in the first region S1 and has risen in temperature, but between the fins 14 arranged at a relatively narrow second interval, the upstream side Since the resistance of the flowing air is larger than that of the first region S1, the air sufficiently hits the fins 14, and a relatively high heat radiation force is obtained.

  Further, in FIG. 2, a part of the air flowing along the outer surface of the duct 9 flows into the inside of the duct 9 from the opening 30 formed in the duct 9. The air that has flowed from the opening 30 enters the second region S2 where the interval between the fins 14 is narrow. Flowing outside the duct 9 and entering the second region S2 from the opening 30 rather than the temperature of the air flowing in the duct 9 from the first region S1 to the second region S2 while taking heat from the fins 14. Since the temperature of the air is lower, the lower temperature air intensively cools the heat generated by the electronic element 10 (L) ′, which is the specific heat source, so that the cooling effect in the second region S2 is particularly high.

  As a result, the temperature gradient generated on the upstream side and the downstream side of the air with the specific position of the electronic element 10 (L) ′, which is the specific heat generation source, as a boundary becomes as small as possible, and the heat generation source (electronic elements 10, 10 ( L) and 10 (L) ′) as a whole can be made uniform in temperature as compared with the prior art.

  The effect of intensively cooling the heat generation of the electronic element 10 (L) ′, which is a specific heat source, varies depending on the size and shape of the opening 30 formed in the duct 9. In order to intensively cool the heat generated by the electronic element 10 (L) ′, which is the specific heat source, the opening 30 having an area corresponding to a part of the region of the electronic element 10 (L) ′ is formed in the electronic element 10 ( L) ′ is preferably provided upstream of the region. If the opening 30 having a half area of the region of the electronic element 10 (L) ′ is provided on the upstream side of the region of the electronic element 10 (L) ′ as in the embodiment, it flows outside the duct 9. Air having a relatively low temperature can be introduced into the duct 9 efficiently and at a high flow rate, and pinpointed to the portion of the fin 14 corresponding to the electronic element 10 (L) ′, which is a specific heat source. Can do. At this time, it is more preferable that the boundary between the first region S1 and the second region S2 of the fin 14 is also set on the upstream side of the electronic element 10 (L) ′ (upstream side immediately above the edge 15). Setting the area of the opening 30 to be equal to or larger than the area of the electronic element 10 (L) ′ is not preferable because the flow velocity of air flowing from the opening 30 becomes small. Further, making the shape of the opening 30 so as to exceed the region of the electronic element 10 (L) ′ allows air from the opening 30 to be moved to a position other than the position corresponding to the electronic element 10 (L) ′. This is not preferable because it will be applied.

  FIG. 5 is a front view showing the heat sink 8 of the unit 3 of the present embodiment. The temperature of the heat sink 8 when the electronic element 10 (L) is used is calculated by simulation using software. It is expressed in contour on top of the drawing.

  As can be seen from the contour in FIG. 5 and the temperature display in the figure, the three positions of the heat sink 8 along the air flow direction F in the left-right direction in the figure have locations H1, H2, slightly higher in temperature than the surroundings. H3 appears. In FIG. 7, the approximate position is indicated by the intersection of two types of arrows in the vertical and horizontal directions. The temperatures of these portions H1, H2, and H3 are approximately 74 to 75 ° C, 73 to 74 ° C, and 76 to 77 ° C, respectively, in order from the left side (upstream side). Thus, the simple temperature gradient in which the temperature of the heat sink 8 rises from upstream to downstream is eliminated, and the difference in temperature from the surroundings at each location is also small. That is, as compared with the heat sink 103 of the comparative example shown in FIG. 7, the temperature of the heat sink 8 as a whole is uniformly reduced, and the electronic elements 10, 10 (L), 10 (L) ′ mounted on the unit 3 The possibility of exceeding the allowable temperature during use is small.

  FIG. 6 is a graph showing the relationship between the position of the heat source (electronic component) provided in the unit 3 (shown on the horizontal axis) and the junction temperature (shown on the vertical axis) when the electronic apparatus 1 is used. The embodiment and the comparative example in which the distance between the fins is constant (for example, the distance between the fins 14 in the first region S1 of the embodiment) are shown in the same drawing.

  The data of the embodiment shown in FIG. 6 is obtained as a general tendency of this embodiment by acquiring and combining a plurality of simulation results as shown in FIG. As understood from this figure, according to the heat sink 8 of this embodiment and the cooling device 7 using the heat sink 8, the temperature gradient with respect to the flow direction F of the cooling air is relaxed, and the temperature of the entire electronic component is reduced. It can be made uniform compared to the conventional case. For this reason, the danger that the temperature of an electronic component will exceed allowable temperature at the time of use can be avoided.

  In the embodiment described above, the fin portion 13 composed of the plurality of fins 14 is divided into two areas, that is, the first area S1 in the upstream where the gap between the fins 14 is wide and the second area S2 in the downstream where the gap between the fins 14 is narrow. The start point of the specific heat source in the air flow direction F is made to coincide with the start point of the second region S2. However, two or more specific heat sources with different positions in the flow direction F are set in the range in accordance with the gist of the present invention that the cooling power is increased by narrowing the interval between the fins 14 at the position of the specific heat source, and the distance between the fins 14 Three or more areas having different values may be set. That is, you may comprise so that the space | interval of the fin 14 may become narrow in steps toward the downstream of the distribution direction F for every specific position of two or more specific heat sources along the distribution direction F.

  In the embodiment described above, there is one specific heat source, and there is also one opening 30 formed in the duct 9. However, if two or more specific heat sources are set, the opening 30 is provided for each specific position. It may be provided.

DESCRIPTION OF SYMBOLS 1 ... Electronic device 3 ... Unit 6 ... Board | substrate 7 ... Cooling device 8 ... Heat sink 9 ... Duct 10, 10 (L) ... Electronic element as a heat generation source 10 (L) '... Electronic element as a specific heat generation source 12 ... Heat sink 8 Base part 13 ... Fin part of heat sink 8 (U) ... Fin part on the upstream side 13 (D) ... Fin part on the downstream side 14, 14a ... Fin 20 ... Inlet of duct 21 ... Outlet of duct 30 ... Formed in duct Opened portion S1... First region upstream of a specific position where the fin interval is wide S2... Second region downstream of the specific position where the fin interval is narrow

The heat sink 8 according to claim 1 is:
A base portion 12 that contacts a plurality of heat sources 10, 10 (L), 10 (L) ′ on an object to be attached, and a fin portion 13 that dissipates heat by air that is provided in the base portion 12 and circulates. , 13 (U), 13 (D),
The fin portions 13, 13 (U), 13 (D)
It is a longitudinal shape along the air flow direction F, and is composed of a plurality of fins 14 and 14a arranged at predetermined intervals in the width direction intersecting the longitudinal direction,
The first interval that is the interval between the fins 14 on the upstream side in the flow direction F is configured to be larger than the second interval that is the interval between the fins 14 and 14a on the downstream side in the flow direction F.
The fin has a relatively large size in the longitudinal direction, a plurality of first fins arranged at the first interval, and a relatively small size in the longitudinal direction. A plurality of second fins arranged at least partially between the first fin and the first fin so that the interval between the first fin and the second interval is the second interval;
When the distance between the fins 14 and 14a is constant, the specific position where the specific heat source 10 (L) ′ that will exceed the allowable temperature at the time of attachment is disposed as a reference. The boundary between the first region S1 in which the interval is the first interval and the second region S2 in which the interval between the fins 14 and 14a is the second interval is set near the upstream side including immediately above the specific position. It is characterized by that.

Claims (2)

Heat is dissipated by a base part (12) that contacts a plurality of heat sources (10, 10 (L), 10 (L) ′) on an object to be attached, and air that is provided in the base part and circulates. With fins (13, 13 (U), 13 (D)),
The fin portion is
It is a longitudinal shape along the air flow direction (F), and is composed of a plurality of fins (14, 14a) arranged at predetermined intervals in the width direction intersecting the longitudinal direction,
The first interval that is the interval between the fins on the upstream side in the flow direction is configured to be larger than the second interval that is the interval between the fins on the downstream side in the flow direction,
When the interval between the fins is constant, the fin is used as a reference at a specific position where the specific heat source (10 (L) ′), which is the heat source that exceeds the allowable temperature at the time of attachment, is disposed. An upstream vicinity including a boundary between the first region (S1) in which the interval is the first interval and the second region (S2) in which the interval between the fins is the second interval, including immediately above the specific position A heat sink (8), characterized in that   The plurality of fins arranged in the width direction of the fin portions (13, 13 (D)) including the plurality of fins (14, 14a) arranged at the second interval are arranged at the first interval. The heat sink (8) according to claim 1, wherein the fin portion (13, 13 (U)) made of (14) is larger than a dimension in the width direction.