Heat dissipation device for wiring board and electronic device using the same

Abstract

To provide a heat dissipation device for wiring boards and electronic devices using the same circuit boards, which has versatility without requiring changes to the heat transfer material configuration for each electronic component mounted on the circuit board.SOLUTION: A heat sink 3 has a heat receiving surface 1 on one side and a heat dissipating surface 2 on the other side, and a flexible heat transfer body 4 arranged on the heat receiving surface side of the heat sink 3. A plurality of grooves 5 are provided in the heat receiving surface 1 of the heat sink 3 so as to be generally parallel to each other. Each groove 5 has first and second rising surfaces 5a, 5b on both sides of its bottom, rising from the bottom toward the opening edge of the groove. A first inclined surface 5c is provided in the middle to upper part of the first rising surface 5a, inclined in the opposite direction to the second rising surface 5b, and a second inclined surface 5d is provided in the middle to upper part of the second rising surface 5b, inclined in the opposite direction to the first rising surface 5a. The inclination angle α of the first inclined surface 5c in the direction opposite to the second rising surface 5b is larger than the inclination angle β of the second inclined surface 5d in the direction opposite to the first rising surface 5a.SELECTED DRAWING: Figure 7

Description

[Technical Field]

[0001] The present invention relates to a heat dissipation device for a wiring board and an electronic device using the same. [Background technology]

[0002] 2. Description of the Related Art Electronic components mounted on wiring boards, such as semiconductor elements, generate a large amount of heat as their information processing speed increases. If such semiconductor elements are left to heat up, the semiconductor elements and other electronic components mounted nearby will thermally deteriorate, so a heat dissipation device for wiring boards is used to actively dissipate the heat from the semiconductor elements.

[0003] Specifically, a heat dissipation device for a wiring board generally comprises a heat sink having a heat receiving surface on one side and a heat dissipating surface on the other side, and a flexible heat transfer body arranged on the heat receiving surface side of the heat sink.The heat transfer body is pressed against the top surface of the semiconductor element (the surface opposite to the mounting surface on the wiring board), and the heat from the semiconductor element is transferred to the heat sink via the heat transfer body, and dissipated from the heat sink. When the heat transfer body is pressed against the upper surface of the semiconductor element, the heat transfer body is recessed due to its flexibility, and the semiconductor element protrudes into this recess.

[0004] However, at this time, a repulsive force is generated in the heat transfer body due to being pressed by the semiconductor element, and this force is applied to the semiconductor element, resulting in mechanical stress for the semiconductor element. Therefore, it has been proposed to provide a recess in a portion of the heat transfer body corresponding to the semiconductor element, into which the semiconductor element can be inserted (see, for example, Patent Document 1 below). [Prior art documents] [Patent documents]

[0005] [Patent Document 1] International Publication No. 2016 / 42739 Summary of the Invention [Problem to be solved by the invention]

[0006] In the above-mentioned prior art document, the heat transfer body must be provided with a recess into which the semiconductor element is inserted, depending on the size of the semiconductor element to be mounted on the circuit board, which makes it non-versatile and ultimately results in an expensive heat dissipation device for wiring boards. Therefore, an object of the present invention is to provide versatility that does not require changing the heat transfer body configuration for each electronic component mounted on the circuit board. [Means for solving the problem]

[0007] To achieve this object, the heat dissipation device for a wiring board of the present invention comprises a heat dissipation body having a heat receiving surface on one side and a heat dissipation surface on the other side, and a flexible heat transfer body arranged on the heat receiving surface side of the heat dissipation body, and the heat receiving surface of the heat dissipation body has a plurality of grooves that continue from one part of the outer periphery of the heat receiving surface to the other part, with adjacent grooves being approximately parallel, and each groove has first and second upright surfaces on both sides of its bottom that rise from the bottom toward the opening edge of the groove, and at least a middle to upper part of the first upright surface has a first inclined surface that is inclined in the opposite direction to the second upright surface, and at least a middle to upper part of the second upright surface has a second inclined surface that is inclined in the opposite direction to the first upright surface, and the inclination angle of the first inclined surface in the direction opposite to the second upright surface is greater than the inclination angle of the second inclined surface in the direction opposite to the first upright surface.

[0008] In addition, in the heat dissipation device for wiring boards of the present invention, the first rising surface of the groove rises approximately vertically from the bottom of the groove to the middle of the groove and has a shape that becomes a first inclined surface from the middle to the top, and the second rising surface of the groove rises approximately vertically from the bottom of the groove to the middle of the groove and has a shape that becomes a second inclined surface from the middle to the top.

[0009] Furthermore, the heat dissipation device for a wiring board of the present invention is provided with heat dissipation fins arranged on the heat dissipation surface side of the heat sink. The heat dissipation device for a wiring board of the present invention further includes a refrigerant pipe disposed on the heat dissipation surface side of the heat dissipation body.

[0010] Furthermore, an electronic device that also uses the heat dissipation device for wiring boards of the present invention comprises a heat dissipation device for wiring boards and a circuit board arranged on the side of the heat transfer body of the heat dissipation device for wiring boards opposite the heat dissipation body, and first and second electronic components are mounted on the heat transfer body side of the circuit board, and the dimension of the second electronic component from the circuit board to the heat transfer body side is larger than the dimension of the first electronic component from the circuit board to the heat transfer body side, and the heat transfer body side surfaces of these first and second electronic components are each in a state where the heat transfer body is pressed toward the heat dissipation body.

[0011] In the electronic device of the present invention, the heat dissipating surface of the heat sink is in surface contact with the heat dissipating member. Furthermore, in the electronic device of the present invention, the heat dissipation member is configured by the inner surface of a main body case that houses the wiring board heat dissipation device and the circuit board.

[0012] In addition, the electronic device of the present invention comprises a heat dissipation device for a wiring board, a circuit board arranged on the surface of a heat transfer body of the heat dissipation device for a wiring board opposite the heat dissipation body, and a biasing means for biasing the circuit board toward the heat transfer body, wherein first and second electronic components are mounted on the heat transfer body side of the circuit board, and the dimension of the second electronic component from the circuit board toward the heat transfer body is larger than the dimension of the first electronic component from the circuit board toward the heat transfer body, and the biasing means causes the heat transfer body side surfaces of the first and second electronic components to press the heat transfer body toward the heat dissipation body.

[0013] Furthermore, in the electronic device of the present invention, the heat dissipating surface of the heat sink is in surface contact with the heat dissipating member. In the electronic device of the present invention, the heat dissipation member is formed by the inner surface of a main body case that houses the wiring board heat dissipation device and the circuit board. [Effects of the Invention]

[0014] As described above, the heat dissipation device for a wiring board of the present invention comprises a heat dissipation body having a heat receiving surface on one side and a heat dissipation surface on the other side, and a flexible heat transfer body arranged on the heat receiving surface side of the heat dissipation body. The heat receiving surface of the heat dissipation body has a plurality of grooves extending from one part of the periphery of the heat receiving surface to the other part, with adjacent grooves being approximately parallel to each other. Each groove has first and second upright surfaces on both sides of its bottom that rise from the bottom toward the opening edge of the groove. At least a middle to upper part of the first upright surface has a first inclined surface that is inclined in the opposite direction to the second upright surface, and at least a middle to upper part of the second upright surface has a second inclined surface that is inclined in the opposite direction to the first upright surface. The inclination angle of the first inclined surface in the direction opposite to the second upright surface is larger than the inclination angle of the second inclined surface in the direction opposite to the first upright surface. Therefore, the heat transfer body can be versatile and does not need to be changed for each electronic component mounted on the circuit board.

[0015] In other words, in the present invention, when the heat transfer body is pressed against an electronic component mounted on a circuit board, the surface of the flexible heat transfer body opposite the electronic component enters the groove provided on the heat-receiving surface side of the heat sink, so the repulsive force from the heat transfer body pressed against the electronic component to the electronic component is small, thereby reducing the mechanical stress on the electronic component.

[0016] Furthermore, the groove of the present invention has first and second rising surfaces on both sides of its bottom that rise from the bottom toward the opening edge of the groove, and a first inclined surface that is inclined in the opposite direction to the second rising surface is provided at least in the middle to upper part of the first rising surface, and a second inclined surface that is inclined in the opposite direction to the first rising surface is provided at least in the middle to upper part of the second rising surface, and the inclination angle of the first inclined surface in the opposite direction to the second rising surface is larger than the inclination angle of the second inclined surface in the opposite direction to the first rising surface.

[0017] Therefore, the heat transfer material pushed into the groove by the electronic component will flow into the groove from the second inclined surface side, and as a result, the heat transfer material pushed by the electronic component will flow smoothly into the groove, thereby further reducing the repulsive force from the heat transfer material pushed by the electronic component to the electronic component, and further reducing the mechanical stress on the electronic component. As a result, the heat transfer body can be provided with versatility without having to be changed for each electronic component mounted on the circuit board.

[0018] Furthermore, in the present invention, a plurality of grooves are provided on the heat receiving surface of the heat dissipating body, continuing from one part of the outer periphery of the heat receiving surface to another part, with adjacent grooves being approximately parallel to each other, and each groove has first and second rising surfaces on both sides of its bottom that rise from the bottom toward the opening edge of the groove, and at least a middle to upper part of the first rising surface is provided with a first inclined surface that is inclined in the opposite direction to the second rising surface, and at least a middle to upper part of the second rising surface is provided with a second inclined surface that is inclined in the opposite direction to the first rising surface, and the inclination angle of the first inclined surface in the direction opposite to the second rising surface is larger than the inclination angle of the second inclined surface in the direction opposite to the first rising surface. Therefore, compared to a heat-receiving surface of a heat radiator that is flat, the heat-receiving surface of the heat radiator has a plurality of grooves formed thereon, which increases the creepage distance and increases the heat-receiving area.

[0019] Furthermore, as described above, the heat transfer material pushed into the groove by the electronic component will flow into the groove from the second inclined surface side of the heat sink. Therefore, the heat transfer material pushed by the electronic component will flow smoothly into the groove, and no air pockets will form between the heat transfer material and the inner surface of the groove of the heat sink, resulting in close contact. As a result, the heat from the electronic component will be effectively dissipated to the heat sink via the heat transfer material, suppressing thermal degradation of the electronic component and nearby components. [Brief explanation of the drawings]

[0020] [Figure 1]1A to 1C are cross-sectional views showing a procedure for applying a heat dissipation device for a wiring board according to one embodiment of the present invention to an electronic device. [Figure 2] FIG. [Figure 3] FIG. [Figure 4] FIG. [Figure 5] FIG. [Figure 6] FIG. [Figure 7] 3 is a cross-sectional view showing the relationship between a heat sink and a heat transfer body of the heat dissipation device for a wiring board according to the first embodiment; FIG. [Figure 8] FIG. [Figure 9] FIG. [Figure 10] FIG. [Figure 11] FIG. [Figure 12] FIG. [Figure 13] FIG. 10 is a cross-sectional view showing a heat dissipation device for a wiring board according to another embodiment of the present invention applied to an electronic device. [Figure 14] FIG. [Figure 15] FIG. 10 is a cross-sectional view showing a heat dissipation device for a wiring board according to still another embodiment of the present invention, applied to an electronic device. DETAILED DESCRIPTION OF THE INVENTION

[0021] (Embodiment 1) 1 to 12 show a state in which a heat dissipation device for a wiring board according to one embodiment of the present invention is applied to an electronic device.

[0022] As shown in Figures 1 to 6, the heat dissipation device for a wiring board in this embodiment comprises a plate-shaped heat dissipation body 3 having a heat receiving surface 1 on one side and a heat dissipation surface 2 on the other side, and a flexible, sheet-shaped heat transfer body 4 arranged on the heat receiving surface 1 side of the heat dissipation body 3.

[0023] The heat sink 3 is made of, for example, copper or aluminum. The heat transfer body 4 is a sheet-shaped material made by filling a gel resin with a high thermal conductivity filler, and has both thermal conductivity and flexibility (for example, "Tathaga" manufactured by Kyodo Giken Chemical Co., Ltd.).

[0024] In this embodiment, both the heat sink 3 and the heat transfer body 4 are rectangular, and the heat receiving surface 1 of the heat sink 3 has a plurality of grooves 5 that continue from one side (part) of the outer periphery of the heat receiving surface 1 to the opposite side (other part) so that adjacent grooves 5 are approximately parallel to each other.

[0025] Each groove 5 continues from one side (part) of the outer periphery of the heat receiving surface 1 to the opposite other side (other part), and the ends of the groove 5 are exposed on both sides of the outer periphery of the heat receiving surface 1. Continuing to explain the grooves 5, in this embodiment, as shown in FIG. 7, each groove 5 has first and second upright surfaces 5a, 5b on both sides of its bottom, which rise from the bottom toward the opening edge of the groove, and a first inclined surface 5c inclined in the opposite direction to the second upright surface 5b is provided at least in the middle to upper part of the first upright surface 5a, and a second inclined surface 5d inclined in the opposite direction to the first upright surface 5a is provided at least in the middle to upper part of the second upright surface 5b.

[0026] In other words, the first rising surface 5a of the groove 5 rises almost vertically from the bottom of the groove 5 to the middle of the groove 5, and becomes a first inclined surface 5c from the middle to the top, and the second rising surface 5b of the groove 5 rises almost vertically from the bottom of the groove 5 to the middle of the groove 5, and becomes a second inclined surface 5d from the middle to the top.

[0027] Further, the inclination angle α of the first inclined surface 5c in the direction opposite to the second rising surface 5b is set larger than the inclination angle β of the second inclined surface 5d in the direction opposite to the first rising surface 5a.

[0028] An example of the case where the heat dissipation device for a wiring board according to this embodiment having the above-described configuration is applied to an electronic device is shown in FIGS. 1 to 6, reference numeral 6 denotes a box-shaped main body case of an electronic device, and first, as shown in Figures 1 and 2, a heat sink 3 is placed on the upper surface (the inner side surface of the main body case 6) of a metal bottom plate 7 of the main body case 6, and then, as shown in Figures 2 and 3, the heat sink 3 is fixed to the upper surface of the metal bottom plate 7 of the main body case 6 with screws 8. In this embodiment, the metal bottom plate 7 of the main body case 6 serves as a heat sink member.

[0029] Since the heat dissipation surface 2 of the heat sink 3 is flat, the heat sink 3 is fixed in surface contact with the upper surface of the metal bottom plate 7 of the main body case 6, which is also flat, so that the heat from the heat sink 3 is dissipated to the bottom plate 7 of the main body case 6 via its heat dissipation surface 2.

[0030] Next, as shown in FIG. 3, a sheet-like heat transfer body 4 is placed on the heat receiving surface 1 of the heat dissipation body 3. Thereafter, a circuit board 9 is placed on the heat transfer body 4 as shown in FIG. At least two semiconductor elements 10 and 11, which are examples of electronic components, are mounted on the lower surface side (heat transfer body 4 side) of this circuit board 9 at a predetermined interval in the horizontal direction.

[0031] The semiconductor elements 10 and 11 have different thicknesses from the circuit board 9 toward the heat conductor 4, with the semiconductor element 11 protruding more toward the heat conductor 4 than the semiconductor element 10. That is, the dimension of the semiconductor element 11 from the circuit board 9 to the heat conductor 4 side is made larger than the dimension of the semiconductor element 10 from the circuit board 9 to the heat conductor 4 side.

[0032] 1 to 6 are boss screws for fixing the circuit board 9 in place, which are fixed on the top surface of the bottom plate 7 of the main body case 6 on both sides of the portion where the heat dissipation surface 2 is provided. Therefore, next, as shown in FIG. 5, screws 13 are threaded into the boss screws 12 from above the circuit board 9 while passing through the through holes 9a on both sides of the circuit board 9.

[0033] 6, when the screw 13 is screwed into the boss screw 12 to the final position, the semiconductor elements 10 and 11 are pressed into the heat transfer body 4. In this embodiment, the circuit board 9, the screw 13, and the boss screw 12 function as the biasing means. As shown in Figures 5 and 6, when the screw 13 is screwed into the boss screw 12 to the final position, the semiconductor elements 10 and 11 are pressed into the heat transfer body 4, and the heat transfer body 4 then moves as shown in Figures 7 to 12.

[0034] 7 to 12 show the bottom surface of the semiconductor element 11. FIG. FIG. 7 shows the state of FIG. 4, with the lower surface of the sheet-like heat transfer body 4 maintained horizontally. As the screw 13 is tightened from the state shown in Figure 5, the heat transfer body 4 is pressed against the underside of the semiconductor element 11, and the part corresponding to the underside of the semiconductor element 11 flows (elastically deforms) into the groove 5 of the heat sink 3 as shown in Figures 8 and 9.

[0035] In the groove 5 of the heat dissipation body 3, the inclination angle α of the first inclined surface 5c in the direction opposite to the second upright surface 5b is larger than the inclination angle β of the second inclined surface 5d in the direction opposite to the first upright surface 5a. Therefore, the flow state (elastic deformation) of the heat transfer body 4 into the groove 5 is such that the heat transfer body 4 flows into the groove 5 faster on the side of the second inclined surface 5d than on the side of the first upright surface 5a, as shown in Figures 8 to 12. This can be explained by decomposing the reaction force that the heat transfer body 4 receives from the first inclined surface 5c and the second inclined surface 5d when it is pushed from above into the upward and horizontal directions at the first inclined surface 5c and the second inclined surface 5d.

[0036] Specifically, since the first inclined surface 5c is closer to a horizontal state than the second inclined surface 5d, as shown in Figure 7, the upward vector R1v obtained by decomposing the reaction force ap of the first inclined surface 5c portion is larger than the upward vector R2v obtained by decomposing the reaction force bp of the second inclined surface 5d portion. Furthermore, since the first inclined surface 5c is closer to a horizontal state than the second inclined surface 5d, as shown in Figure 7, the horizontal vector R1h obtained by decomposing the reaction force ap of the first inclined surface 5c portion is smaller than the horizontal vector R2h obtained by decomposing the reaction force bp of the second inclined surface 5d portion. As a result, the flow state of the heat transfer body 4 into the groove 5 is such that the heat transfer body 4 flows into the groove 5 on the second inclined surface 5d side faster than on the first upright surface 5a side, as shown in Figures 8 to 12.

[0037] In this way, as shown in Figures 8 to 12, if the heat transfer material 4 is made to flow into the groove 5 faster on the side of the second inclined surface 5d than on the side of the first upright surface 5a, the heat transfer material 4 will flow smoothly into the groove 5, and ultimately, the heat transfer material 4 pressed by the semiconductor element 11 will flow smoothly into the groove 5, thereby reducing stress on the semiconductor element 11.

[0038] Furthermore, when the heat transfer body 4 flows into the groove 5 of the heat sink 3 from the second inclined surface 5d side, the air in the groove 5 is also smoothly expelled out of the groove 5, thereby improving adhesion with the heat transfer body 4 within the groove 5. As a result, the heat of the semiconductor element 11 is efficiently dissipated to the heat transfer body 4, the heat sink 3, and the bottom plate 7 of the main body case 6, preventing thermal degradation of the semiconductor element 11 and other electronic components in the vicinity.

[0039] Another feature of this embodiment is that even if a semiconductor element 10 that is shorter than the semiconductor element 11 is mounted on the circuit board 9 in the vicinity of the semiconductor element 11, the semiconductor element 10 can also be mounted smoothly. In other words, even if a tall semiconductor element 11 is present, the heat transfer body 4 facing it can be smoothly pushed into the groove 5, allowing the circuit board 9 to move smoothly toward the heat sink 3. As a result, the short semiconductor element 10 can also be brought into contact with the heat transfer body 4, and the heat from the semiconductor element 10 can be efficiently dissipated to the heat transfer body 4, the heat sink 3, and the bottom plate 7 of the main body case 6, preventing thermal degradation of the semiconductor element 10 and other electronic components in the vicinity. 7 to 12, arrow A indicates the pushing force from the circuit board 9 side, and arrow B indicates the flow direction of the heat transfer body 4.

[0040] In addition, in this embodiment, the heat receiving surface 1 of the heat dissipator 3 is provided with a plurality of grooves 5 that continue from one part of the outer periphery of the heat receiving surface 1 to another part, with adjacent grooves 5 being approximately parallel to each other. Each groove 5 has first and second rising surfaces 5a, 5b on both sides of the bottom thereof, which rise from the bottom toward the opening edge of the groove.

[0041] Furthermore, at least in the middle to upper part of the first rising surface 5a, a first inclined surface 5c is provided which is inclined in the opposite direction to the second rising surface 5b, and at least in the middle to upper part of the second rising surface 5b, a second inclined surface 5d is provided which is inclined in the opposite direction to the first rising surface 5a, and the inclination angle of the first inclined surface 5c in the opposite direction to the second rising surface 5b is larger than the inclination angle of the second inclined surface 5d in the opposite direction to the first rising surface 5a. Therefore, compared to a heat receiving surface 1 of the heat dissipation body 3 that is flat, the surface distance is longer and the heat receiving area is wider because multiple grooves 5 are formed on the heat receiving surface 1 of the heat dissipation body 3.

[0042] Furthermore, the heat transfer body 4 pressed into the groove 5 by the semiconductor elements 10 and 11, which are provided as an example of electronic components, will behave as described above by flowing into the groove 5 from the second inclined surface 5d of the heat sink 3. Therefore, the heat transfer body 4 pressed by the semiconductor elements 10 and 11 flows smoothly into the groove 5, and no air pockets are created between the heat transfer body 4 and the inner surface of the groove 5 of the heat sink 3, resulting in close contact. As a result, the heat from the semiconductor elements 10 and 11 is effectively dissipated to the heat sink 3 via the heat transfer body 4, thereby suppressing thermal degradation of the semiconductor elements 10 and 11 and the components in their vicinity.

[0043] (Embodiment 2) 13, 14 and 15 show another embodiment of the present invention, and to avoid complication of explanation, the same components as those in the above embodiment are given the same reference numerals.

[0044] In this embodiment, a heat sink 14 is provided inside a box-shaped main body case 6 of an electronic device. On the upper surface of the heat sink 14 (the side opposite to the heat sink 3), for example, as shown in FIG. 15, heat sink fins 15 and refrigerant pipes (not shown) are provided.

[0045] In this example, the heat sink 3 is fixed to the heat sink 14 with the screws 8, and then the heat transfer body 4 and the circuit board 9 are attached from below with the screws 13. In this case, first, the heat transfer body 4 is placed on the semiconductor elements 10 and 11 on the circuit board 9 as shown in FIG. 14, and then the circuit board 9 is moved toward the heat sink 14 using the screws 13. In this example, as in the above embodiment, an extremely large heat dissipation effect and stress relief effect on the semiconductor elements 10 and 11 are achieved. [Explanation of symbols]

[0046] 1 Heat receiving surface 2 Heat radiation surface 3 Heat sink 4 Heat Transfer Material 5 grooves 5a First rising surface 5b Second rising surface 5c First inclined plane 5d Second inclined plane 6 Main unit case 7 Bottom plate 8 screws 9 Circuit Board 10 Semiconductor elements 11 Semiconductor elements 12 Boss screws 13 screws 14 Heat sink 15 Heat dissipation fin

Claims

1. a heat sink having a heat receiving surface on one side and a heat radiating surface on the other side, and a flexible heat transfer body disposed on the heat receiving surface side of the heat sink; a plurality of grooves are provided on the heat receiving surface of the heat radiator, the grooves extending from one part of the periphery of the heat receiving surface to another part, so that adjacent grooves are substantially parallel to each other; Each groove has first and second rising surfaces on both sides of a bottom thereof, the rising surfaces rising from the bottom toward an opening edge of the groove; a first inclined surface inclined in an opposite direction to the second inclined surface is provided at least in a middle to upper portion of the first inclined surface; a second inclined surface inclined in an opposite direction to the first inclined surface is provided at least in a middle to upper portion of the second inclined surface; The heat dissipation device for a wiring board, wherein the inclination angle of the first inclined surface in the direction opposite to the second rising surface is larger than the inclination angle of the second inclined surface in the direction opposite to the first rising surface.

2. the first rising surface of the groove rises substantially vertically from the bottom of the groove to the middle of the groove, and forms a first inclined surface from the middle to the upper part, 2. The heat dissipation device for a wiring board according to claim 1, wherein the second raised surface of the groove rises substantially vertically from the bottom of the groove to the middle of the groove, and forms a second inclined surface from the middle to the top.

3. 2. The heat dissipation device for a wiring board according to claim 1, further comprising heat dissipation fins disposed on the heat dissipation surface of said heat sink.

4. 2. The heat dissipation device for a wiring board according to claim 1, further comprising a refrigerant pipe disposed on the heat dissipation surface side of said heat sink.

5. a circuit board disposed on a surface of a heat transfer body of the heat dissipation device for a wiring board opposite to the heat dissipation body, An electronic device in which first and second electronic components are mounted on the heat transfer body side of the circuit board, the dimension of the second electronic component from the circuit board to the heat transfer body side is larger than the dimension of the first electronic component from the circuit board to the heat transfer body side, and the heat transfer body side surfaces of these first and second electronic components are each in a state where the heat transfer body is pressed toward the heat sink side.

6. The electronic device according to claim 5 , wherein the heat dissipating surface of the heat sink is in surface contact with a heat dissipating member.

7. 7. The electronic device according to claim 6, wherein the heat dissipation member is formed by an inner surface of a main body case that houses the wiring board heat dissipation device and the circuit board.

8. a heat dissipation device for a wiring board according to any one of claims 1 to 4, a circuit board arranged on a surface of a heat transfer body of the heat dissipation device for a wiring board opposite to the heat dissipation body, and a biasing means for biasing the circuit board toward the heat transfer body, An electronic device in which first and second electronic components are mounted on the heat transfer body side of the circuit board, the dimension of the second electronic component from the circuit board to the heat transfer body side is larger than the dimension of the first electronic component from the circuit board to the heat transfer body side, and the biasing means causes the heat transfer body side surfaces of the first and second electronic components to press the heat transfer body toward the heat sink side.

9. The electronic device according to claim 8 , wherein the heat dissipating surface of the heat sink is in surface contact with a heat dissipating member.

10. 10. The electronic device according to claim 9, wherein the heat dissipation member is formed by an inner surface of a main body case that houses the wiring board heat dissipation device and the circuit board.

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