JP5640616B2 - Heat dissipation structure for electronic components - Google Patents

Description

  The present invention relates to a heat dissipation structure for an electronic component having, as components, a substrate to which the electronic component is soldered, a case for holding the substrate, and the like.

  In recent years, with the development of electronic technology, electronic devices are becoming smaller in size, and electronic devices that generate heat to prevent deterioration of the characteristics of electronic components when using electronic components that generate a large amount of heat for a long time. Efficient heat dissipation from components is required. As the heat dissipation structure, for example, as shown in Patent Document 1, a heat-generating electronic component is soldered to one surface of the substrate, and a heat transfer sheet is provided between the heat dissipation member disposed to face the other surface of the substrate. There is a sandwiched heat dissipation structure. The heat transfer sheet is in contact with the other surface of the substrate and the flat portion of the heat dissipation member, and transfers heat generated by the heat generating electronic component from the substrate to the heat dissipation member.

  However, in the heat dissipation structure of Patent Document 1, since the heat transfer sheet is in pressure contact with the other surface of the substrate and the flat portion of the heat dissipation member without any gap, the reaction force that the substrate receives from the heat transfer sheet increases as the area of the substrate increases. May increase and the substrate may be distorted. When the substrate is distorted, stress may act on the joint portion (soldering portion) between the substrate and the heat generating electronic component, leading to a decrease in strength at the joint portion.

  Therefore, there is Patent Document 2 as an example for solving the above problem. In Patent Document 2, a heat transfer sheet is sandwiched between a substrate having a circuit element soldered on the front surface and a flat portion of a case (heat radiating member) disposed to face the back surface of the substrate. There is an electronic component mounting body in which a groove is provided in a flat portion. Since no stress acts on the substrate from the portion of the heat transfer sheet facing the groove provided in the case, the strain generated on the substrate can be reduced.

  As another heat dissipation structure, for example, as disclosed in Patent Document 3, the upper surface of an electronic component mounted on the surface of a printed wiring board is covered with a heat dissipation sheet, a heat dissipation plate is disposed on the back surface of the printed wiring board, and the heat dissipation sheet is dissipated. There is a heat dissipation structure of an electronic device fixed to a board or a printed wiring board (see FIG. 4).

JP-A-11-354696 JP 2008-112839 A JP 2001-257490 A

  However, in the electronic component mounting body of Patent Document 2, when a board on which a large number of heat generating electronic parts are mounted is fixed to the case by screwing in several places, depending on the distance from the place where the board is distorted and the screw is tightened, There may be variations in the adhesion between the back surface of the substrate and the heat transfer sheet. For this reason, the heat dissipation performance as expected may not be ensured.

  Further, in the heat dissipation structure of Patent Document 3, when a plurality of electronic components are covered with a heat dissipation sheet, the adhesion between the electronic component and the heat dissipation sheet varies due to distortion of the heat dissipation sheet. For this reason, especially the heat dissipation performance of the electronic component mounted in the position away from the place where the heat dissipation sheet is fixed may not be ensured. Further, since the heat sink is in pressure contact with the back surface of the printed wiring board without any gap, the reaction force that the board receives from the heat sink increases as the area of the board increases. For this reason, a distortion | strain arises in a board | substrate, the intensity | strength of a junction part falls by the stress which acts on the junction part of a board | substrate and an electronic component, and peeling of a junction part may generate | occur | produce.

  The present invention has been made to solve the above-described problems, and provides a heat dissipation structure that can efficiently dissipate heat generated by an electronic component mounted on a substrate.

According to a first aspect of the present invention, there is provided a substrate on which a plurality of electronic components are soldered to at least one surface, a first heat dissipating member having a first groove provided in a flat portion, and the substrate. Between the electronic component and the first heat transfer sheet that is provided between the first heat radiating member and transmits heat generated in the electronic component from the substrate to the first heat radiating member via the flat portion. A second groove having a second groove at the position of the first heat radiating member and the second heat radiating member fixed to the first heat radiating member, and is sandwiched between the electronic component and the second heat radiating member, and is generated in the electronic component. A second heat transfer sheet that transmits heat to the second heat radiating member, and a first slack shape portion on the first heat transfer sheet and a slack shape portion on the second heat transfer sheet. And the first groove is provided with the first slack shape portion of the first heat transfer sheet. Both wherein the said second groove provided in the first groove and overlapping position, in which the second slack shaped portion of the second heat transfer sheet is provided.

In the second problem-solving means of the present invention, the first slack shape portion does not contact the substrate and enters the space inside the first groove .

Further, according to a third problem solving means of the present invention, the second slack shape portion is not in contact with the substrate, and the second heat transfer sheet enters the space inside the second groove. Is.

According to a fourth problem solving means of the present invention, the first groove has a V-shaped cross-sectional shape.

In the fifth problem-solving means of the present invention, the second groove has a V-shaped cross-sectional shape.

  According to the first solving means of the present invention, the first and second heat dissipating members are arranged so as to sandwich the electronic component and the substrate on which the electronic component is mounted from both sides via the first and second heat transfer sheets. Fixed. For this reason, the adhesiveness of a 1st heat-transfer sheet | seat and a board | substrate and the adhesiveness of a 2nd heat-transfer sheet | seat and an electronic component can be ensured equally. Thereby, heat can be efficiently transmitted to each of the first and second heat radiating members, and characteristic deterioration due to heat generation of the electronic component can be reduced.

  In addition, by providing the first groove in the flat surface portion of the first heat radiating member, when the heat generated from the electronic component is radiated or when the substrate and the first and second heat radiating members are fixed by screws or the like, The stress of one heat transfer sheet can be released at the first groove portion, and the stress applied to the substrate can be reduced. For this reason, the intensity | strength of the junction part of an electronic component and a board | substrate is securable.

In the above configuration, a plurality of electronic components are provided on the substrate , and the first groove is provided between the electronic components, whereby the first groove is provided in the lower part of the electronic component of the first heat dissipation member. Therefore, heat transfer from the electronic component to the first heat radiating member is not hindered.

In addition , by providing the second groove on the second heat radiating member , the stress of the second heat transfer sheet can be released to the second groove portion in addition to the space around the electronic component, and the stress applied to the substrate Can be reduced more effectively.

Moreover , since the 1st slack shape part of a 1st heat transfer sheet does not contact a board | substrate , the stress added to a 1st heat transfer sheet can be absorbed in this part, and the stress added to a board | substrate can be reduced.

In addition , since the second slack shape portion of the second heat transfer sheet does not contact the substrate , the stress applied to the second heat transfer sheet can be absorbed by this portion, and the stress applied to the electronic component can be reduced. .

Moreover , under the condition that the width and depth of the groove are the same, the cross-sectional area of the groove is smaller, and the strength of the heat radiating member is more easily secured.

It is a disassembled perspective view of the heat dissipation structure of the electronic component which concerns on this invention. It is sectional drawing of the heat dissipation structure of the electronic component which concerns on this invention. It is a figure which shows other embodiment of the groove | channels 22 and 25. FIG. (A) is a perspective view which shows the heat dissipation structure of the conventional electronic device, (b) is sectional drawing of the structure of (a).

  Embodiments of the present invention will be described below with reference to the drawings.

FIG. 1 is an exploded perspective view of a heat dissipation structure for an electronic component according to the present invention. In FIG. 1, the heat dissipation structure for electronic components includes a plurality of electronic components 11, a substrate 10, two cases (a first heat dissipation member 20 and a second heat dissipation member 23), and two heat transfer sheets (first It consists of a heat transfer sheet 30 and a second heat transfer sheet 31). The substrate 10 has a plurality of electronic components 11 (heat generating components such as FETs and transistors) for constituting a circuit joined to the surface 10a by soldering. The case 20 (first heat radiating member) is formed of a metal having high thermal conductivity or the like, and has a flat portion 21 for installing the substrate 10. In the present embodiment, the planar portion 21 is provided with grooves 22 (first grooves) in a grid pattern. However, depending on the shape and arrangement of the electronic component 11 mounted on the substrate 10, the planar portion 21 may be provided only in one direction. The groove to be formed can also be applied, and it is sufficient if the contact area where the substrate 10 receives the repulsive force from the heat transfer sheet 30 can be reduced. The heat transfer sheet 30 is made of a material having good adhesion, high thermal conductivity, and high elasticity. As the heat transfer sheet 30, for example, a sheet (silicon sheet) formed of silicon rubber can be applied. The heat transfer sheet 30 is disposed so as to be sandwiched between the back surface 10 b of the substrate 10 and the flat portion 21 of the case 20. The case 23 (second heat radiating member) is formed of a metal having high thermal conductivity, like the case 20, and has a flat portion 24 for installation on the electronic component 11. In the present embodiment, the planar portion 24 is provided with grooves 25 (second grooves) in a grid pattern, but depending on the shape and arrangement of the electronic component 11, a groove formed only in one direction is also applicable. it can. Similar to the heat transfer sheet 30, the heat transfer sheet 31 is made of a material having good adhesion, high thermal conductivity, and high elasticity. The heat transfer sheet 31 is disposed so as to be sandwiched between the electronic component 11 mounted on the surface 10 a of the substrate 10 and the flat portion 24 of the case 23.

  FIG. 2 is a sectional view of a heat dissipation structure for an electronic component according to the present invention. The substrate 10 is formed of an insulating material such as glass epoxy, and patterns 12 and 13 made of copper foil are provided on the front surface 10a and the back surface 10b, respectively. The through hole 14 penetrates the pattern 12, the substrate 10, and the pattern 13 in the thickness direction of the substrate 10 (the vertical direction in FIG. 2). The inner peripheral surface of the through hole 14 is plated with a material having good conductivity such as copper, and the pattern 12 and the pattern 13 are electrically connected through the through hole 14. The electronic component 11 is a surface mounting type whose surface of the electrode or packaging is metallized, and is soldered to a predetermined position of the pattern 12. The heat generated by the electronic component 11 is transferred from the pattern 12 on the front surface 10a of the substrate 10 to the pattern 13 on the back surface 10b through the through hole 14. The substrate 10 is installed on the flat portion 21 of the case 20 via the heat transfer sheet 30, and is fixed to the case 20 using the screws 16 together with the case 23 installed on the electronic component 11 via the heat transfer sheet 31. .

  The heat transfer sheet 30 is sandwiched between the back surface 10b (pattern 13) of the substrate 10 and the flat portion 21 of the case 20, and is in contact (pressure contact) with the back surface 10b of the substrate 10 and the flat portion 21 of the case 20. . Thus, the heat generated by the electronic component 11 is efficiently transferred from the pattern 12 of the substrate 10 to the through hole 14, the pattern 13, the heat transfer sheet 30, and the flat surface portion 21 of the case 20. To the outside. Further, the heat transfer sheet 31 is sandwiched between the upper surface 15 of the electronic component 11 mounted on the surface 10 a of the substrate 10 and the flat portion 24 of the case 23, and the upper surface 15 of the electronic component 11 and the flat portion of the case 23. 24 is in contact (pressure contact). Thus, the heat generated by the electronic component 11 is efficiently transmitted from the heat transfer sheet 31 to the flat portion 24 of the case 23 and is released to the outside from the case 23 that is a heat radiating member.

  In the present embodiment, the plurality of electronic components 11 have the same height from the surface 10 a of the substrate 10 to the upper surface 15 of the electronic component 11, but electronic components having different package heights are mounted on the substrate 10. In the case, the adhesiveness between the upper surfaces 15 of all the electronic components 11 and the heat transfer sheets 31 can be improved by making the height of the flat portion 24 of the case 23 match the height of the electronic components to be mounted. It can be ensured evenly. As another method, the thickness of the heat transfer sheet 31 is changed according to the electronic components 11 having different heights, for example, within the range of the heat transfer sheet 31 in contact with the upper surface 15 of one electronic component 11. By sticking the separate heat transfer sheets, the adhesion between the upper surfaces 15 of all the electronic components 11 and the heat transfer sheets 31 can be ensured evenly. It is obvious that the heat dissipation structure of the present invention can be applied even when one electronic component 11 is mounted on the substrate 10 instead of a plurality, or when it is mounted on both surfaces of the substrate 10.

  Grooves 22 and 25 are provided in the flat portion 21 of the case 20 and the flat portion 24 of the case 23, respectively. The grooves 22 and 25 are formed in a concave shape with respect to the thickness direction of the substrate 10, and their cross-sectional shapes are rectangular. The grooves 22 and 25 may be formed in a concave shape with respect to the thickness direction of the substrate 10. For example, the cross-sectional shape may be V-shaped (see FIG. 3) or a semicircular shape. If the cross-sectional shape of the grooves 22 and 25 is V-shaped with respect to the rectangle, the cross-sectional area of the grooves 22 and 25 can be smaller under the condition that the width and depth of the grooves 22 and 25 are the same. The strength of the flat portion 24 of the portion 21 and the case 23 is more easily secured. Furthermore, since the cross-sectional areas of the cases 20 and 23 increase, the heat dissipation performance to the outside of the heat transmitted from the heat transfer sheets 30 and 31 is improved.

  The groove 22 has a lower portion of the pattern 13 in the vicinity of the electronic component 11 on the substrate 10 in the planar portion 21 so as not to prevent heat from being transferred from the substrate 10 (pattern 13) to the planar portion 21 of the case 20. It is formed in other parts. That is, the groove 22 is disposed between the electronic components 11, and the groove 22 is not provided in the lower portion of the electronic component 11 in the flat portion 21 of the case 20. Therefore, heat transfer from the electronic component 11 to the case 20 (planar portion 21) is not hindered. Similarly, the groove 25 has a portion other than the upper portion of the upper surface 15 in the vicinity of the electronic component 11 in the flat portion 24 so as not to prevent heat from being transferred from the upper surface 15 of the electronic component 11 to the flat portion 24 of the case 23. It is formed in the part. That is, the groove 25 is disposed between the electronic components 11, and the groove 25 is not provided in the upper portion of the electronic component 11 in the flat portion 24 of the case 23. Accordingly, heat transfer from the electronic component 11 to the case 23 (planar portion 24) is not hindered.

  Further, at the position where the heat transfer sheet 30 overlaps the groove 22, at least a part of the surface of the heat transfer sheet 30 facing the back surface 10 b of the substrate 10 is not in contact with the back surface 10 b and enters a space inside the groove 22. A slack shape portion 32 is provided. By providing the slack shape portion 32, the stress applied to the heat transfer sheet 30 generated when the substrate 10 or the case 20 expands or contracts due to heat or when the substrate 10 and the cases 20 and 23 are screwed is relaxed. 32 can absorb. Similarly, at the position where the heat transfer sheet 31 overlaps the groove 25, at least a part of the surface of the heat transfer sheet 31 facing the surface 10 a of the substrate 10 does not contact the substrate 10, and the heat transfer sheet 31 is not in the groove 25. A slack shape portion 33 is provided as a portion entering the inner space. Alternatively, at a position where the heat transfer sheet 31 overlaps the space between the electronic components 11, at least a part of the surface of the heat transfer sheet 31 facing the flat portion of the case 23 does not contact the case 23, A slack shape portion 33 as a portion that enters the space may be provided. Similar to the slack shape portion 32, the slack shape portion 33 can absorb the stress applied to the heat transfer sheet 31.

  As described above, according to the heat dissipation structure for an electronic component according to the present invention, the groove 22 is provided in the flat portion 21 in contact with the heat transfer sheet 30 in the case 20. Stress does not act on the facing part. For this reason, compared with the case where the flat surface portion 21 of the case 20 does not have the groove 22, the contact area where the heat transfer sheet 30 is pressed against the back surface 10 b of the substrate 10 is reduced, and the back surface 10 b of the substrate 10 receives from the heat transfer sheet 30. The power is reduced. In addition, since the heat transfer sheet 30 is provided with the slack shape portion 32 as a portion entering the space inside the groove 22, the slack shape portion 32 can absorb the stress applied to the heat transfer sheet 30. Thereby, when the case 20 is fixed to the substrate 10 with the screws 16 or when heat generated by the electronic component 11 is radiated, distortion generated in the substrate 10 can be reduced, and a plurality of electronic components are formed on the surface 10a of the substrate 10. It is possible to prevent the solder joining 11 from cracking and the pattern 12 (13) from being peeled off from the substrate 10.

  Further, since the groove 25 is provided in the flat portion 24 in contact with the heat transfer sheet 31 in the case 23, no stress acts on the portion of the heat transfer sheet 31 that faces the groove 25. For this reason, compared with the case where the flat part 24 of the case 23 does not have the groove | channel 25, the reaction force which the upper surface 15 of the electronic component 11 receives from the heat-transfer sheet 31 becomes small. In addition, since the heat transfer sheet 31 is provided with the slack shape portion 33 as a portion entering the space inside the groove 25, the slack shape portion 33 can absorb the stress applied to the heat transfer sheet 31. Thereby, when the case 23 is fixed to the substrate 10 with the screw 16, the stress received by the electronic component 11 can be reduced, the electronic component 11 is cracked, and the pattern 12 of the electronic component 11 and the substrate 10 is soldered. Therefore, it is possible to prevent the bonded solder from being broken or the pattern 12 from being peeled off from the substrate 10. The stress of the heat transfer sheet 31 can be released to the space around the electronic component 11.

  Further, the heat generated by the electronic component 11 is transmitted from the pattern 13 of the substrate 10 to the heat transfer sheet 30 and the case 20 (first heat radiating member), and the heat transfer sheet 31 and the case from the upper surface 15 of the electronic component 11. 23 (second heat dissipating member) is emitted to the outside from two routes of the route of transmission. In addition, since the cases 20 and 23 are fixed via the heat transfer sheets 30 and 31 so as to sandwich the electronic component 11 and the board on which the electronic component 11 is mounted from both sides, the adhesion between the components of the two routes described above. Is secured. For this reason, the heat accumulated in the circuit due to the heat generated by the electronic component 11 can be efficiently released to the outside, and the deterioration of characteristics of the electronic component or circuit can be reduced.

  In order to reduce the reaction force that the substrate 10 receives from the heat transfer sheets 30 and 31, for example, a single heat transfer sheet 30 corresponding to the heat radiation of the electronic component 11 is disposed between the flat portion 21 of the case 20 and the substrate 10. The single heat transfer sheet 31 may be sandwiched between the flat portion 24 of the case 23 and the upper surface 15 of the electronic component 11. In this case, the heat transfer sheets 30 and 31 can be easily arranged without being fixed by screwing or the like, and the assembly of the heat transfer sheets 30 and 31 is also ensured.

10 surface of substrate 10a (one surface)
10b Back side (the other side)
11 Electronic component 20 Case (first heat dissipation member)
23 Case (second heat dissipation member)
21, 24 Plane portion 22 Groove (first groove)
25 groove (second groove)
30 Heat transfer sheet (first heat transfer sheet)
31 Heat transfer sheet (second heat transfer sheet)
32, 33 Slack shape part (first slack shape part, second slack shape part)

Claims (5)

A substrate on which a plurality of electronic components are soldered to at least one surface;
A first heat dissipating member having a first groove provided in the planar portion;
A first heat transfer sheet that is provided between the substrate and the first heat dissipation member, and transmits heat generated in the electronic component from the substrate to the first heat dissipation member via the flat portion;
A second heat dissipating member having a second groove at a position between the electronic components and fixed to the first heat dissipating member;
A second heat transfer sheet that is sandwiched between the electronic component and the second heat dissipation member and transmits heat generated in the electronic component to the second heat dissipation member, and
The first heat transfer sheet has a first slack shape portion and the second heat transfer sheet has a slack shape portion,
In the first groove, the first slack shape portion of the first heat transfer sheet is provided,
A heat dissipation structure for an electronic component, wherein the second slack shape portion of the second heat transfer sheet is provided in the second groove provided at a position overlapping with the first groove . 2. The heat dissipation structure for an electronic component according to claim 1, wherein the first slack shape portion is not in contact with the substrate and enters a space inside the first groove . 2. The heat dissipation structure for an electronic component according to claim 1 , wherein the second slack shape portion is not in contact with the substrate, and the second heat transfer sheet enters a space inside the second groove . The heat dissipation structure for an electronic component according to claim 1 , wherein the first groove has a V-shaped cross-sectional shape . The heat dissipation structure for an electronic component according to claim 1 , wherein the second groove has a V-shaped cross-sectional shape .

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