JP2013225581A - Heat radiation structure of circuit board - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a heat radiation structure of a circuit board which improves heat diffusion efficiency and shield effect.SOLUTION: A heat radiation structure of a circuit board includes: a circuit board 10; a heating component 20 mounted on the circuit board 10; and a heat sink 30 at least partially covering a component mounting surface of the circuit board 10 and grounded on the circuit board 10. The heat sink 30 includes: a plate body part 31 including a first surface 31a facing the heating component 20 and a second surface 31b located at the opposite side of the first surface 31a; and a dent part 34 that is formed so as to be recessed from the second surface 31b side of the plate body 31 and protrude toward the first surface 31a side. The heat sink 30 is fixed to the circuit board 10 with a facing surface of the dent part 34, which faces the heating component 20, placed in indirect or direct contact with the heating component 20.

Description

  The present invention relates to a heat dissipation structure for a circuit board.

  Conventionally, a circuit board, a heat generating component mounted on the circuit board, a heat sink that at least partially covers the component mounting surface of the circuit board and is grounded to the circuit board, and a notch is provided in the plate body portion of the heat sink A heat dissipation structure of a circuit board that heats a heat-generating component through a heat dissipation plate by bringing a cantilever-shaped contact piece formed by bending it into contact with the heat-generating component is known (see, for example, Patent Document 1). .

Japanese Utility Model Publication No. 61-27297

  However, in the conventional heat dissipation structure of a circuit board, the contact piece that contacts the heat-generating component is formed in a cantilever shape by providing a notch in the plate body, and the contact piece is part of the edge of the plate body. Since they are connected, the heat transfer path from the contact piece to the plate body is limited, and there is a problem that the heat diffusion efficiency is poor.

  In addition, since electromagnetic waves enter and radiate from a cut portion (gap) on the heat sink formed to provide the contact piece, there is a problem that the shielding effect of the heat sink is reduced.

  Therefore, the present invention solves the conventional problems, that is, an object of the present invention is to provide a heat dissipation structure for a circuit board that improves heat diffusion efficiency and shielding effect.

  A heat dissipation structure for a circuit board according to the present invention includes a circuit board, a heat-generating component mounted on the circuit board, and a heat sink that at least partially covers a component mounting surface of the circuit board and is grounded to the circuit board. The heat radiating plate includes a plate main body portion including a first surface facing the heat generating component and a second surface opposite to the first surface, and the second surface side of the plate main body portion. A recess portion that is recessed and protrudes toward the first surface side, and the heat dissipation plate causes the facing surface of the recess portion facing the heat generating component to contact the heat generating component indirectly or directly. In this state, the above-described problem is solved by being fixed to the circuit board.

  In this invention, the structure which heat-radiates a heat-emitting component is employ | adopted by making the hollow part formed by denting the 2nd surface side of a board main-body part and making it protrude in a 1st surface side contact a heat-generating component. By this, there is no notch (gap) in the plate body part, and all the edges of the dent part are connected to the plate body part, so the heat diffusion path from the dent part contacting the heat generating component to the plate body part increases, Thermal diffusion efficiency can be improved.

  Further, since there is no cut portion (gap) in the plate main body, electromagnetic waves can be prevented from entering and radiating from the cut portion (gap), and the shielding effect by the heat sink can be improved.

It is a top view which shows the thermal radiation structure of the circuit board which is one Example of this invention. It is the top view which shows the state which mounted the heat sink on the package, and sectional drawing seen in the arrow direction in the AA line position. It is a perspective view which shows a package and a heat sink.

  Hereinafter, an embodiment of a heat dissipation structure for a circuit board according to the present invention will be described with reference to the drawings.

  As shown in FIGS. 1 to 3, the circuit board heat dissipation structure according to an embodiment of the present invention includes a circuit board 10, a heating component 20 that is an electronic component mounted on the circuit board 10, and a circuit board 10. A heat radiating plate 30 that at least partially covers the component mounting surface, and a housing 40 that houses a package 70 composed of the circuit board 10, the heat generating component 20, and the like are provided.

  The heat radiating plate 30 is formed from a conductive metal having a high thermal conductivity such as aluminum and is grounded to the circuit board 10. As shown in FIG. 2 and FIG. 3, the heat radiating plate 30 is a flat plate main body portion including a first surface 31 a facing the heat generating component 20 and a second surface 31 b opposite to the first surface 31 a. 31, a plurality of standing portions 32 erected from the edge of the plate body portion 31 toward the circuit board 10 side, a plurality of screw holes 33 formed on the distal end side of the standing portion 32, and the plate body It has integrally the hollow part 34 which the 2nd surface 31b side of the part 31 was dented and protruded to the 1st surface 31a side.

  The heat radiating plate 30 is easily formed by bending a flat plate-shaped metal formed in a predetermined shape at a predetermined location and performing press processing for forming the recessed portion 34.

  As shown in FIGS. 1 to 3, a sheet-like heat conducting member 60 having elasticity is fixed to the facing surface of the recess 34 facing the heat generating component 20. The heat conducting member 60 may be any member such as a rubber sheet or a silicon sheet as long as it has high thermal conductivity and elasticity.

  As shown in FIG. 2, the heat radiating plate 30 is fixed to the circuit board 10 with the facing surface of the recess 34 facing the heat generating component 20 in contact with the heat generating component 20 via a heat conducting member 60. .

  The circuit board 10, the heat sink 30, and the housing 40 are fixed to each other by a common fixing screw 50. Reference numeral 11 shown in FIG. 3 is a screw hole formed in the circuit board 10.

  In the present embodiment thus obtained, by bringing the heat sink 30 that also functions as a shield of the package 70 into contact with the heat-generating component 20, a sheet sink, a blower fan, or the like that is restricted in terms of cost or product life can be obtained. Without use, efficient heat dissipation of the heat generating component 20 can be realized easily and at low cost.

  Further, the heat generating component 20 is radiated by bringing the recessed portion 34 formed by denting the second surface 31b side of the plate main body portion 31 and projecting it toward the first surface 31a into contact with the heat generating component 20. By adopting the configuration, there is no cut portion (gap) in the plate main body portion 31 and all the edge portions of the hollow portion 34 are connected to the plate main body portion 31, so that the plate main body from the hollow portion 34 that contacts the heat generating component 20. The number of heat diffusion paths to the portion 31 is increased, and the heat diffusion efficiency can be improved.

  In addition, since there is no cut portion (gap) in the plate body portion 31, electromagnetic waves can be prevented from entering and radiating from the cut portion (gap), and the shielding effect of the heat radiating plate 30 can be improved.

  Further, the elastic heat conducting member 60 is fixed to the opposing surface of the depression 34, and the depression 34 is brought into contact with the heat generating component 20 through the heat conducting member 60. The heat generating component 20 and the recess 34 can be reliably brought into contact without being affected by the outer shape and the like.

  Further, since the heat conductive member 60 is elastically deformed by being sandwiched between the recess 34 and the heat generating component 20, even if there are irregularities or steps on the outer surface of the heat generating component 20, the heat conductive member 60 is interposed therebetween. A large contact area between the heat generating component 20 and the recessed portion 34 can be ensured, and the heat dissipation efficiency can be improved.

  In the above-described embodiment, the description has been given assuming that one heat generating component is mounted on the circuit board. However, the number of heat generating components mounted on the circuit board may be any number.

  Further, in the above-described embodiment, the heat sink is described as having one recess, but a plurality of recesses may be formed in the heat sink.

  Further, regarding the correspondence between the depression and the heat generating component, the depression may be brought into contact with the heat generating component in a one-to-one relationship depending on the quantity and position of the heat generating component. For this reason, the recessed portion may be brought into contact with the heat generating component.

  In the above-described embodiment, the heat generating component and the heat radiating plate are indirectly contacted via the heat conductive member. However, the heat generating component and the heat radiating plate are directly connected without using the heat conductive member. You may make it contact.

  In the above-described embodiment, the fixing screw is used as the fixing means between the constituent members. However, the specific fixing means between the constituent members may be anything such as fitting and fixing. However, when a fixing screw is employed as a fixing means between the constituent members, the fixing relationship between the constituent members is stabilized, which is more preferable.

  In the above-described embodiment, the circuit board, the heat radiating plate, and the housing are fixed together by a common fixing screw. However, the components may be fixed individually. However, when the circuit board, the heat radiating plate, and the housing are fixed together by using a common fixing screw, it is more preferable because the number of screwing points can be suppressed and assembly work and the like are facilitated.

DESCRIPTION OF SYMBOLS 10 ... Circuit board 11 ... Screw hole 20 ... Heat-generating component 30 ... Heat sink 31 ... Plate main-body part 31a ... 1st surface 31b ... 2nd surface 32 ... · Standing portion 33 ··· Screw hole 34 ··· Depressed portion 40 · · · Case 50 · · · Fixing screw 60 · · · Heat conducting member 70 · · · Package

Claims (4)

A circuit board, a heat generating component mounted on the circuit board, and a heat sink that at least partially covers a component mounting surface of the circuit board and is grounded to the circuit board,
The heat radiating plate includes a plate main body portion including a first surface facing the heat-generating component and a second surface opposite to the first surface, and a concave portion on the second surface side of the plate main body portion. And having a recess projecting toward the first surface,
The heat radiating plate is fixed to the circuit board in a state where the facing surface of the recess facing the heat generating component is in contact with the heat generating component indirectly or directly. Heat dissipation structure. An elastic heat conducting member is fixed to the facing surface of the recess,
2. The heat dissipation structure for a circuit board according to claim 1, wherein the recess is in contact with the heat generating component via the heat conducting member.   3. The circuit board heat dissipation structure according to claim 1, wherein the circuit board and the heat radiating plate are fixed to each other by a fixing screw. 4. A housing for housing the circuit board;
4. The circuit board heat dissipation structure according to claim 1, wherein the casing, the circuit board, and the heat sink are fixed to each other by a common fixing screw. 5.

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