JP2005252175A - Cooling mechanism of circuit device - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a cooling mechanism of a circuit device, capable of lowering an increase in the temperature of an electronic component arranged on the upper side of a heat generating component. <P>SOLUTION: Semiconductor elements 2a, 2b are mounted on circuit boards 1a, 1b vertically arranged. The semiconductor element having a large heat value is arranged on the circuit board 1a closer to a cooling member 4. For instance, as for an electric power converting circuit, a large power IGBT is mounted on the circuit board 1a as the semiconductor element 2a, and a control IC is mounted on the circuit board 1b as the semiconductor element 2b. A heat-shielding member 5 is arranged between the circuit boards 1a, 1b. The air, heated by the heat of the semiconductor element 2a, convects as shown by the curve L1 and lets the heat out to the heat radiating fin 53. The convection is blocked by a partition plate 52 and the air will not reach the circuit board 1b. This can suppress increase in the temperature of the semiconductor element 2b. <P>COPYRIGHT: (C)2005,JPO&NCIPI

Description

  The present invention relates to a cooling mechanism for a circuit device in which electronic components are arranged with a space above heating components.

  A semiconductor element used as a switching element of an inverter which is a power conversion device generates a large amount of heat because a large current flows. For this reason, a cooling device is often provided to suppress an increase in element temperature. As an example of the cooling device, there is an apparatus including a flat plate-like heat radiating board portion to which a semiconductor element is attached and a large number of heat radiating fins protruding from the lower surface side of the heat radiating board portion. The heat of the semiconductor element is transmitted to the heat radiating fins via the heat radiating substrate portion, and is radiated from the surface of the heat radiating fins to the atmosphere (for example, see Patent Document 1).

  Further, when there are a plurality of circuit boards on which semiconductor elements are mounted, these circuit boards may be arranged one above the other in order to make the space compact (see, for example, Patent Document 2).

JP-A-7-226466 JP 2003-69270 A

  However, when the circuit boards are arranged one above the other, the temperature of the circuit board provided on the upper side is likely to increase due to the heat released from the semiconductor elements mounted on the lower circuit board, and the semiconductor elements on the circuit board are overheated. There was a risk of a situation. Further, even if the above-described cooling device having the radiation fins is attached to the upper circuit board, a sufficient heat radiation effect cannot be obtained due to the heat from the lower circuit board.

  The present invention relates to a cooling mechanism of a circuit device in which an electronic component is disposed above a heat generating component, and a shielding member that is thermally connected to a cooling means is disposed between the heat generating component and the electronic component. On the surface of the shielding member facing the heat-generating component, a plurality of fins are formed so as to protrude. The wall portion is formed so as to surround the region where the fin protrudes, and the wall portion prevents air convection from the heating component placement space to the electronic component placement space.

  According to the present invention, the wall portion prevents air convection from the heat generating component disposition space to the electronic component disposition space, thereby reducing the temperature rise of the electronic component.

  Hereinafter, the best mode for carrying out the present invention will be described with reference to the drawings. FIG. 1 is a diagram showing an embodiment of a cooling mechanism according to the present invention. Reference numerals 1a and 1b denote circuit boards on which semiconductor elements 2a and 2b are mounted, which are supported on the cooling unit 4 by heat conductive support members 3a and 3b, respectively. The cooling unit 4 may be cooled by a cooling device using Peltier effect, cooling water, or the like, or may be constituted by a metal heat sink and cooled by air cooling.

  For example, in the case of an inverter circuit, an IGBT, a MOSFET, or the like that generates a large amount of heat is mounted on the circuit board 1a close to the cooling unit 4, and a control IC is mounted on the circuit board 1b. In general, these circuit boards 1a and 1b are covered on the sides and above by a casing (not shown). In some cases, the semiconductor element 2a having a large calorific value is directly mounted on the cooling unit 4 via an insulating heat conductive sheet or the like.

  Heat generated in the semiconductor elements 2a and 2b is transferred from the circuit boards 1a and 1b to the cooling unit 4 through the support members 3a and 3b. Between the circuit board 1a and the circuit board 1b, a heat shielding member 5 including a heat shielding plate 51 and a partition plate 52 provided on the back side of the heat shielding plate 51 is disposed with a gap therebetween. ing. The heat shielding plate 51 is attached to an intermediate portion of the support member 3b.

  FIG. 2 is a cross-sectional view taken along the line AA of FIG. 1, and illustration of the cooling unit 4 and the supporting members 3a and 3b is omitted. A plurality of heat radiating fins 53 project from the back surface of the heat shielding plate 51. The partition plate 52 is formed so as to surround a region where the heat radiating fins 53 are provided. The height h1 of the partition plate 52 is set to be larger than the height h2 of the radiation fins 53. For example, the lower end of the partition plate 52 is extended to the vicinity of the circuit board 1a.

  FIG. 3 is a diagram of the back side of the heat shielding member 5 as viewed from the circuit board 1a side, and three types of examples regarding the cross-sectional shape of the radiating fins 53 and their arrangement are shown in (a) to (b). In any case, the shape and arrangement of the radiating fins 53 are such that convection air is effectively applied to the radiating fins 53 to absorb heat, and the convection is not hindered.

  In the first example shown in FIG. 3A, the cross-sectional shape of the radiating fin 53A is rectangular, and the radiating fin 53A provided in the regions S1 and S2 is provided with the longitudinal direction aligned in the vertical direction in the figure. The radiating fins 53A provided in the regions S3 and S4 and in the center are provided with the longitudinal direction aligned in the horizontal direction in the figure. When arranged in this way, the long side of the cross section of the radiating fin 53A is directed in the central direction.

  Further, the radiating fins 53 </ b> A in rows arranged in the front-rear direction (regions S <b> 3, S <b> 4) or the left-right direction (regions S <b> 1, S <b> 2) are alternately arranged. For example, when comparing the first row of radiating fins 53A and the second row of radiating fins from the right of the region S1, the vertical positions in the figure are shifted and are staggered. By adopting such a fin structure, the air flow is not hindered and heat exchange with the radiating fins 53A is performed efficiently. In addition, you may arrange | position the radiation fin 53A circularly so that the cross-sectional long side of each radiation fin 53A may face the center. Also in this case, the inner rows and the outer rows of radiating fins 53A are alternately arranged to facilitate air flow in the peripheral direction.

  In the second example shown in FIG. 3B, the columnar radiating fins 53B are regularly arranged in the vertical direction and the horizontal direction in the drawing. Also in this case, when the upper and lower rows and the left and right rows are compared, the radiation fins 53B are alternately arranged. By making the radiation fins 53B cylindrical, convection can easily flow and the contact area can be made relatively large, so that effective heat radiation can be performed. The shape of the radiating fin 53B may be a cylinder instead of a column, and the cross-sectional shape may be an ellipse or the like. In addition, the arrangement thereof may be concentric.

  In the third example shown in FIG. 3C, each of the radiating fins 53C is formed so as to extend radially around the center of the heat shielding plate 51 and has a structure in which convection air easily flows. . In the case of the radiating fin 53C shown in FIG. 3C, the area of the radiating fin 53C is large, and when it is manufactured by casting, the air from the mold can easily escape, and it is easy to improve the yield in casting.

  In FIG. 2, a streamline L1 schematically shows a convection state of air heated by the circuit board 1a. The heat generated in the semiconductor element 2a mounted on the circuit board 1a warms the air near the circuit board, particularly the air near the center, and flows upward as indicated by the streamline L1. And after colliding with the radiation fin 53, as shown to Fig.3 (a), it convects in the direction of the partition plate 52 so that it may pass between the radiation fins 53A. As described above, the height h1 of the partition plate 52 is set such that h1> h2 with respect to the height h2 of the heat radiating fins 53, so that air falls along the partition plate 52 in the direction of the circuit board 1a.

  In FIGS. 3A to 3C, the streamline L1 is shown only in the upper left area of the figure. In the case of the radiating fins 53B shown in FIG. 3B, the streamline L1 is the same as that in the case of FIG. 3A, but in the case of FIG. 3C, the radiating fins 53C are formed radially. Therefore, the warmed air flows radially from the central region of the heat shielding plate 51. In this way, while the heated air flows between the radiation fins 53, heat is transmitted to the radiation fins 53 and the air is cooled. The heat transmitted to the radiating fins 53 is released to the cooling unit 4 via the heat shielding plate 51 and the support member 3b (see FIG. 1).

  As described above, in this embodiment, since the heat shielding member 5 provided with the partition plate 52 is disposed between the circuit board 1a and the circuit board 1b, the influence of heat generated by the semiconductor element 2a on the circuit board 1b, that is, In addition, the influence of radiant heat and the influence of convection heat can be prevented. For example, when there is no partition plate 52, the warmed air spreads around the heat shield plate 51 and then flows around the edge of the heat shield plate 51 to the circuit board 1 b side. As a result, the temperature of the circuit board 1b may rise and the semiconductor element 2b may overheat. However, in this embodiment, the partition plate 52 can prevent such convection escaping to the circuit board 1b side, and can prevent overheating of the semiconductor element 2b.

  In the above-described embodiment, the support members 3a and 3b and the heat shielding member 5 use aluminum or copper metal having high thermal conductivity so that heat conduction or heat dissipation from the warmed air is effectively performed. Is preferred. For example, the heat shield member 5 and the support members 3a and 3b may be integrally formed by aluminum casting, or the integrally formed heat shield member 5 may be screwed or welded to the support member 3b. In addition to the heat transfer function, the support members 3a and 3b also function as grounds for the circuit boards 1a and 1b. However, these are not limited to the cylindrical shape as shown in FIG. can do.

  FIG. 4 is a view showing a first modification of the cooling mechanism, and is a cross-sectional view similar to FIG. Here, the convex part 54 different from the radiation fin 53 was formed in the back surface of the heat shielding board 5. The tip (lower end) of the convex portion 54 is in thermal contact with the semiconductor element 2a of the circuit board 1a via an inclusion 55 such as a heat dissipation sheet or an adhesive. The inclusion 55 may be omitted.

  As described above, the heat of the semiconductor element 2a is transmitted to the cooling unit 4 through the circuit board 1a and the support member 3a, but here, in addition to this, the heat is released to the heat shielding plate 1 through the convex part 54. Can do. Therefore, it is effective for a semiconductor element 1a having a large heat dissipation amount such as an IGBT. In the above-described example, the convex portion 54 is different from the heat radiating fins 53. However, the length of some of the heat radiating fins 53 may be increased to replace the convex portion 54.

  FIG. 5 is a view showing a second modification of the cooling mechanism. It is sectional drawing similar to the case of FIG. The above-described heat shielding plate 51 in FIG. 2 has a higher temperature at the center due to the heat generated by the semiconductor element 2a. Therefore, in the heat shielding plate 51A of FIG. 5, a convex shape is formed on the lower side centering on the portion facing the semiconductor element 2a, which is a heating element. By adopting such a shape, the convection of the warmed air to the periphery is smoothly performed, and the heat is efficiently dispersed. Moreover, since the central part where the temperature of the heat shielding plate 51A is high is moved away from the circuit board 1b, the influence of radiant heat on the circuit board 1b can be reduced. As a result, the temperature rise of the circuit board 1b and the semiconductor element 2b can be suppressed.

  Further, the heat shielding plate 51A shown in FIG. 5 has the same thickness at both the peripheral portion and the central portion, but the thickness of the convex central portion as in the heat shielding plate 51B shown in FIG. 6 is increased. May be. When the thickness of the central portion is increased in this way, the heat capacity of the heat shielding plate 51B is increased, the amount of heat that can be absorbed by the heat shielding plate 51B is increased, and the temperature rise of the heat shielding plate 51B can be suppressed. As a result, the temperature rise of the circuit board 1b can also be suppressed.

  Furthermore, as shown in FIG. 7, a low thermal conductivity member 56 such as a rubber sheet may be disposed on the upper surface of the heat shielding plate 51B. For example, when the amount of heat generated by the semiconductor element 2a is large, the temperature rise of the heat shielding plate 51B tends to be large, and convective heat and radiant heat on the upper surface of the heat shielding plate 51B become large, leading to a temperature rise of the circuit board 1b. However, by providing the low thermal conductivity member 56 as shown in FIG. 7, the heat transfer to the circuit board 1b can be reduced. As a material of the low thermal conductivity member 56, a resin or the like can be used in addition to a rubber material, and they are attached to the upper surface of the heat shielding plate 51B.

  In the above-described embodiment, the case where the semiconductor elements 2a and 2b are mounted on the circuit boards 1a and 1b has been described as an example. However, the present invention is not limited to such a case. For example, the semiconductor element 2a is cooled as described above. The cooling mechanism of the present invention can also be applied when mounted on the plate 4. That is, when the semiconductor elements 2a and 2b are arranged up and down, by disposing the heat shielding member 5 provided with the partition plate 52 between them, the semiconductor element 2b can be separated from the lower semiconductor element 2a. Thermal effects can be reduced. Furthermore, the same effect is exhibited not only for semiconductor elements but also for general electronic components.

  In the correspondence between the embodiment described above and the elements of the claims, the semiconductor element 2a is a heat generating component, the semiconductor element 2b is an electronic component, the cooling member 4 is a cooling means, and the partition plate 52 is a wall portion. Constitute. In addition, the present invention is not limited to the above embodiment as long as the characteristics of the present invention are not impaired.

It is a figure which shows one Embodiment of the cooling mechanism by this invention. It is sectional drawing of AA of FIG. It is a figure which shows the cross-sectional shape and arrangement | positioning form of a radiation fin, (a) is a 1st example, (b) is a 2nd example, (c) is a 3rd example. It is sectional drawing which shows a 1st modification. It is a figure which shows the 2nd modification of a cooling mechanism. It is a figure which shows the 3rd modification of a cooling mechanism. It is a figure which shows the 4th modification of a cooling mechanism.

Explanation of symbols

DESCRIPTION OF SYMBOLS 1a, 1b Circuit board 2a, 2b Semiconductor element 3a, 3b Support member 4 Cooling part 5 Thermal shielding member 51, 51A, 51B Thermal shielding board 52 Partition board 53, 53A-53C Radiation fin 54 Protrusion part 56 Low heat conductive member

Claims (8)

A cooling mechanism for a circuit device in which an electronic component is disposed above a heat generating component,
A shielding member disposed between the heat generating component and the electronic component and thermally connected to the cooling means;
A plurality of fins projecting from the surface on a surface of the shielding member facing the heat generating component, and a space in which the electronic component is disposed from a space in which the heat generating component projects so as to surround a region in which the fin projects. A cooling mechanism for a circuit device, characterized in that a wall portion for preventing convection of air is formed. In the cooling mechanism of the circuit device according to claim 1,
A cooling mechanism for a circuit device, wherein a part of the shielding member is brought into contact with the heat generating component. In the cooling mechanism of the circuit device according to claim 1 or 2,
A cooling mechanism for a circuit device, wherein a portion of the shielding member facing the heat generating component has a shape that is convex toward the heat generating component and a shape that is concave toward the electronic component. In the cooling mechanism of the circuit device according to claim 1 or 2,
A cooling mechanism for a circuit device, characterized in that a portion of the shielding member facing the heat generating component is thickened so as to protrude toward the heat generating component. In the cooling mechanism of the circuit device according to any one of claims 1 to 4,
A cooling mechanism for a circuit device, wherein a low thermal conductivity member having a thermal conductivity smaller than that of the shielding member is disposed on a surface of the shielding member facing the electronic component. In the cooling mechanism of the circuit device according to any one of claims 1 to 5,
The fins are plate-shaped fins having a substantially rectangular cross section, and the fins are arranged so that the long side of the cross section faces the convection direction of the air in the arrangement space of the heat generating component, and the convection direction is A cooling mechanism for a circuit device, wherein the fins arranged on the front and rear sides are arranged shifted in a direction perpendicular to the convection direction. In the cooling mechanism of the circuit device according to any one of claims 1 to 5,
The fins are cylindrical or columnar fins, and the fins arranged at the front and rear with respect to the air convection direction in the space where the heat generating components are arranged are shifted in a direction perpendicular to the convection direction. A cooling mechanism for a circuit device. In the cooling mechanism of the circuit device according to any one of claims 1 to 5,
The fins are plate-shaped fins having a substantially rectangular cross section, and the fins are respectively arranged so that the long side of the cross section is radial with respect to a portion of the shielding member facing the heat generating component. Circuit device cooling mechanism.

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