JP2017017147A - Heat sink and circuit board having the same - Google Patents

Abstract

PROBLEM TO BE SOLVED: To enable cutoff of electromagnetic noise and cooling of electronic components with a simple configuration without maximally preventing interruption of an air stream formed by a cooling fan at maximum.SOLUTION: A heat sink mounted on a circuit board including a plurality of electronic components comprises a conductive rectangular plate member, and mounted under an electrically grounded state at a position where the main surface thereof blocks an air stream formed on a circuit board. Out of a contact portion in contact with the circuit board on the main surface and a separate portion spaced from the circuit board on the main surface, the separate portion is divided into two areas by a straight line extending in a direction away from the circuit board, and any one of the two areas is bent toward the downstream side of the air stream with the straight line as a fulcrum.SELECTED DRAWING: Figure 1

Description

  The present invention relates to a heat sink installed on a circuit board including a plurality of electronic components and a circuit board including the heat sink.

  In an electronic device such as a copying machine, various electronic components are arranged on a circuit board. The electronic component generates heat as the electronic device operates. If the electronic component becomes hot, malfunction or deterioration may occur, and some measures against heat are required. As heat countermeasures, for example, forced air cooling using a cooling fan or heat sink made of a member having high thermal conductivity is attached to an electronic component to dissipate heat.

  Further, electromagnetic noise is radiated from the electronic components as the electronic device operates. Since electronic components may malfunction due to the influence of electromagnetic noise, countermeasures against electromagnetic noise are required in addition to the thermal countermeasures described above. For example, Patent Document 1 below discloses a technique for blocking electromagnetic noise radiated from an electronic component and cooling the electronic component by covering the electronic component and its periphery with a heat sink.

JP-A-10-70383 JP 2007-59731 A

  The technique disclosed in Patent Document 1 requires a part that covers an electronic component and a part that receives air blown by a cooling fan, so that there is a problem that the structure of the heat sink becomes complicated.

  In the above-mentioned Patent Document 2, electromagnetic noise is cut off and electronic components are cooled using a simple configuration of an L-shaped plate-shaped heat sink. There is a problem that the blocking performance is lowered.

  The present invention has been made in view of the above circumstances, and an object thereof is to enable electromagnetic noise blocking and electronic component cooling with a simple configuration without blocking air flow formed by a cooling fan as much as possible. To do.

  A heat sink according to one aspect of the present invention is a heat sink installed on a circuit board including a plurality of electronic components, and the heat sink is composed of a conductive rectangular plate-like member, the main surface of which is the circuit board. Among the contact portions that are in contact with the circuit board on the main surface and spaced apart from the circuit board, in the state of being electrically grounded to a position that blocks the airflow formed in the The separated portion is divided into two regions by a straight line extending in a direction away from the circuit board, and one of the two regions is bent toward the downstream side of the air flow with the straight line as a fulcrum. It is a heat sink.

  In addition, a circuit board according to another aspect of the present invention includes a plurality of electronic components disposed on the circuit board and the heat sink, and at least some of the plurality of electronic components include: The circuit board is disposed on the air flow, and the heat sink is disposed on an upstream side of an electronic component disposed on the air flow.

  According to the present invention described above, it is possible to block electromagnetic noise and cool electronic components with a simple configuration without blocking the air flow formed by the cooling fan as much as possible.

It is a perspective view which shows the circuit board with which the heat sink concerning one Embodiment of this invention was installed. It is a top view which shows the circuit board with which the heat sink concerning one Embodiment of this invention was installed. It is a figure which shows the manufacture process of the heat sink concerning one Embodiment of this invention. (A) And (B) is a figure which shows the flow of the air in the circuit board with which the heat sink concerning one Embodiment of this invention was installed, and the flow of electromagnetic noise. (A) shows the heat sink and cooling fan concerning one embodiment of the present invention, and (B) thru / or (D) show the heat sink and cooling fan concerning a comparative example.

  Hereinafter, a heat sink according to an embodiment of the present invention will be described with reference to the drawings.

  FIG. 1 is a perspective view showing a circuit board on which a heat sink according to an embodiment of the present invention is installed. FIG. 2 is a top view showing a circuit board on which a heat sink according to an embodiment of the present invention is installed.

  The circuit board 10 is composed of an insulating or low-conductivity member such as a glass epoxy material, a resin material, or a ceramic material, and various electronic components for realizing the functions of an electronic device such as a copying machine are provided on the upper surface thereof. Is arranged. The circuit board 10 is formed with a wiring pattern for connecting the arranged electronic components.

  In the example shown in FIGS. 1 and 2, a transformer 21, integrated circuits 22A, 22B, 22C, capacitors 23A, 23B, 23C, and other electronic components 24A, 24B, 24C, 24D, etc. are arranged on the upper surface of the circuit board 10. It is installed. The transformer 21 converts an AC voltage supplied from a power source (not shown) into a DC voltage. The integrated circuits 22A, 22B, and 22C are SoCs (System-on-Chips) in which various electronic elements such as transistors are integrated on one chip, and include a plurality of input terminals and output terminals. Capacitors 23A, 23B, and 23C are electrolytic capacitors, ceramic capacitors, and the like. Note that some of the electronic components disposed on the upper surface of the circuit board 10 are not denoted by reference numerals in order to ensure the visibility of the drawings.

  These electronic components generate heat with the operation of an electronic device such as a copying machine. Since the malfunction and deterioration may occur when the electronic component becomes high temperature, the cooling fan 30 is disposed on the circuit board 10 in order to cool the electronic component. The cooling fan 30 includes a plurality of blades (not shown) and a motor that rotates the blades. In the example shown in FIGS. 1 and 2, the cooling fan 30 forms an air flow toward the minus X direction above the circuit board 10.

  The electronic components disposed on the upper surface of the circuit board 10 are forcibly air-cooled by the air flow. In particular, the electronic components disposed on the air flow are efficiently cooled. Since the transformer 21 is a member that generates a relatively large amount of heat among the electronic components disposed on the upper surface of the circuit board 10, the transformer 21 is located on the air flow formed by the cooling fan 30 and close to the cooling fan 30. It is arranged.

  Here, in the air flow formed by the cooling fan 30, the heat sink 40 is disposed on the downstream side of the transformer 21. The heat sink 40 is disposed so that its main surface is orthogonal to the upper surface of the circuit board 10. For this reason, a part of the air flow formed by the cooling fan 30 is blocked by the main surface of the heat sink 40.

  The heat sink 40 is composed of a single rectangular plate-like member having excellent heat conductivity and conductivity such as aluminum and copper, and is thermally connected to the integrated circuit 22A through a heat path 50 such as a heat pipe. Yes. The heat generated in the integrated circuit 22 </ b> A is transferred to the heat sink 40 via the heat path 50 and is forcedly cooled by the heat sink 40.

  Here, the main surface of the heat sink 40 is divided into a contact portion 41 in contact with the circuit board 10 and a separation portion 42 located above the contact portion 41 and separated from the circuit board 10. A part of the separation portion 42 is bent by approximately 90 degrees toward the downstream side of the air flow formed by the cooling fan 30. Specifically, the separation portion 42 is divided into two regions (left portion 43 and right portion 44) by a straight line 45 extending in a direction away from the circuit board 10, and one of the two regions is a straight line 45. Is bent toward the downstream side of the airflow. In the present embodiment, the right portion 44 is bent toward the downstream side of the air flow. Thereby, the separation part 42 of the heat sink 40 becomes L-shaped, and an opening is formed in a part of the separation part 42. On the other hand, the contact portion 41 of the heat sink 40 is not bent. That is, the contact portion 41 is in contact with the linear region on the circuit board 10.

  The heat sink 40 is electrically grounded. Since the heat sink 40 is composed of a member having excellent conductivity such as aluminum or copper, it functions as a shield for electromagnetic noise radiated from electronic components such as the transformer 21 and is radiated from electronic components such as the transformer 21. Electromagnetic noise can be blocked.

  FIG. 3 is a diagram showing a manufacturing process of a heat sink according to an embodiment of the present invention. As shown in this figure, the heat sink 40 is prepared with a single plate-like member (see the upper part of FIG. 3), determines a region to be bent in the plate-like member (see the middle part of FIG. 3), and It can be manufactured by bending the region (see the lower part of FIG. 3). Thus, the heat sink 40 has a simple structure and can be manufactured by a simple process. Although details will be described later, the range of the bending area is set in accordance with the arrangement area of the electronic component arranged on the downstream side of the air flow from the heat sink 40. For this reason, the heat sink 40 suitable for the arrangement (type, number, position, etc. of electronic components) of the electronic components on the circuit board 10 can be manufactured by adjusting the bending area in the plate member. Usually, in order to manufacture a heat sink suitable for the arrangement of electronic components, it is necessary to design a heat sink exclusively for the heat sink, which is very laborious. On the other hand, in the heat sink according to the embodiment of the present invention, a heat sink suitable for the arrangement of electronic components can be manufactured by a simple operation of adjusting a bending area in one plate-like member. .

  The above is the description of the configuration of the heat sink according to the embodiment of the present invention. Then, the effect by the said heat sink is demonstrated.

  4 (A) and 4 (B) are views showing the flow of air and the flow of electromagnetic noise on the circuit board on which the heat sink according to one embodiment of the present invention is installed.

  First, the flow of air will be described. As shown in FIG. 4A, the air flows F <b> 1 to F <b> 4 generated by the cooling fan 30 pass over the transformer 21 and reach the heat sink 40. Of the air flows F1 to F4 that have reached the heat sink 40, the air flows F1 and F2 are blocked by the contact portion 41 of the heat sink 40 and the left portion 43 of the separation portion 42. On the other hand, some of the air flows F3 and F4 are blocked by the contact portion 41 of the heat sink 40, but the air flowing upward passes through the opening formed in the separation portion 42. As a result, the air flows F3 and F4 reach the electronic components such as the capacitors 23A, 23B, and 23C disposed on the downstream side of the air flow from the heat sink 40, and the electronic components can be forcibly cooled.

  Here, as in the heat sink according to the embodiment of the present invention, a single plate-like member is not bent to form an opening through which air passes, but a single plate-like member is notched. It is conceivable to form an opening through which air passes by forming. However, when a notch is formed in one plate-like member, the area in contact with the air blown by the cooling fan 30 is reduced by the amount of the notch and the cooling performance is lowered. On the other hand, in the heat sink according to one embodiment of the present invention, an opening through which air passes is formed by bending a single plate-like member, so the area in contact with the air blown by the cooling fan 30 changes. Absent. That is, it is possible to forcibly cool the electronic components disposed on the downstream side of the air flow with respect to the heat sink 40 while maintaining the cooling performance before bending one plate-like member to some extent.

  Next, the flow of electromagnetic noise will be described. As shown in FIG. 4A, electromagnetic noises N1 and N2 are radiated from a transformer 21 in accordance with the operation of an electronic device such as a copying machine. In this case, since the contact portion 41 of the heat sink 40 is not bent and no opening is formed unlike the separation portion 42, electromagnetic noises N1 and N2 radiated from the transformer 21 are not leaked by the contact portion 41 of the heat sink 40. Blocked. As a result, it is possible to reduce the amount of electromagnetic noise N1 and N2 that propagates to electronic components such as capacitors 23A, 23B, and 23C disposed on the downstream side of the airflow from the heat sink 40.

  Here, unlike the heat sink according to the embodiment of the present invention, it is conceivable that not only the separated portion 42 is L-shaped but both the separated portion 42 and the contact portion 41 of the heat sink 40 are L-shaped. . However, in this case, although the effect of forcibly cooling the electronic component by causing the air flow by the cooling fan 30 to reach the electronic component disposed on the downstream side of the air flow with respect to the heat sink 40 is radiated from the transformer 21. Since a part of the electromagnetic noise leaked from the contact portion 41, the effect of blocking the electromagnetic noise is reduced. On the other hand, in the heat sink according to the embodiment of the present invention, it is possible to effectively block electromagnetic noise in addition to cooling electronic components with a simple configuration.

  FIG. 4B shows the flow of air and the flow of electromagnetic noise when the area to be bent is expanded compared to the heat sink shown in FIG. 4B, electronic components 25A and 25B are newly provided in addition to the capacitors 23A, 23B, and 23C on the downstream side of the airflow from the heat sink 40. As shown in FIG. 4 (B), the air flow F2 blocked by the heat sink 40 in FIG. The electronic parts such as the electronic parts 25A and 25B are reached without being blocked by the light. As a result, in addition to the capacitors 23A, 23B, and 23C, electronic components such as the electronic components 25A and 25B can be forcibly cooled. Thus, the range of the air passing through the heat sink 40 can be adjusted by changing the range of the right portion 44 that bends in the heat sink 40. That is, the range of the right portion 44 that bends in the heat sink 40 is set so that the air blowing by the cooling fan 30 to the electronic components disposed on the downstream side of the air flow from the heat sink 40 is not hindered. More electronic components disposed downstream of the flow can be forced air cooled.

(Supplement 1)
The heat sink 40 is an electronic component (a transformer in the embodiment described above) having a noise amount generated during operation of an electronic device such as a copier among a plurality of electronic components disposed on the upper surface of the circuit board 10. 21). Thereby, electromagnetic noise generated from the entire circuit board 10 can be effectively suppressed.

(Supplement 2)
As described above, in the heat sink according to the embodiment of the present invention, the right portion 44 of the left portion 43 and the right portion 44 of the separation portion 42 is bent toward the downstream side of the air flow with the straight line 45 as a fulcrum. doing. In this state, the positional relationship between the cooling fan 30 and the heat sink 40 is as shown in FIG.

  Here, as shown in FIG. 5B, the right portion 44 is not bent at the straight line 45 as a fulcrum, but the right portion 44 is bent at a straight line 46 parallel to the upper surface of the circuit board 10 as a fulcrum. think of. Even in this case, it is possible to block electromagnetic noise and cool electronic components arranged on the downstream side of the air flow. However, the air that has passed through the opening of the separation portion 42 is blocked by the right portion 44 and thus the circuit board 10 side. There is a problem of not flowing. Therefore, the heat sink according to the embodiment of the present invention is superior in the cooling performance of the electronic component disposed on the downstream side of the air flow as compared with the case shown in FIG.

(Supplement 3)
As described above, in the heat sink according to the embodiment of the present invention, the angle at which the right portion 44 of the separation portion 42 is bent is set to approximately 90 degrees. This angle is set so that the bent right portion 44 is parallel to the main flow direction of the air flow. Here, the angle at which the right portion 44 is bent as shown in FIG. 5C is larger than 90 degrees, and the angle at which the right portion 44 is bent as shown in FIG. 5D is smaller than 90 degrees. Think about the case.

  When the angle at which the right portion 44 bends as shown in FIG. 5C is larger than 90 degrees, the air that has passed through the opening of the separation portion 42 does not flow along the right portion 44 and is away from the right portion 44. Flowing. For this reason, there exists a problem that the efficiency of the heat exchange between the air which passed the opening of the separation part 42, and the right part 44 is bad. Therefore, the heat sink according to one embodiment of the present invention is superior in cooling performance as compared to the case shown in FIG.

  Further, when the angle at which the right portion 44 bends as shown in FIG. 5D is smaller than 90 degrees, the air that has passed through the opening of the separated portion 42 is likely to be blocked by the right portion 44. For this reason, there arises a problem that it is difficult for the air flow to reach the electronic components arranged on the downstream side of the air flow. Therefore, the heat sink according to the embodiment of the present invention is superior in the cooling performance of the electronic component disposed on the downstream side of the air flow as compared with the case shown in FIG.

(Modification)
The present invention is not limited to the configuration of the above embodiment, and various modifications can be made. The configuration and processing shown in the above embodiment using FIGS. 1 to 5 are only one embodiment of the present invention, and are not intended to limit the present invention to the configuration and processing.

  For example, although the case where the electronic component is arrange | positioned in the downstream of the airflow rather than the heat sink 40 was demonstrated, this invention is not necessarily limited to this case. A heat sink similar to the heat sink 40 may be disposed downstream of the heat sink 40 in the air flow.

DESCRIPTION OF SYMBOLS 10 Circuit board 21 Transformer 22A Integrated circuit 23A Capacitor 24A Electronic component 30 Cooling fan 40 Heat sink

Claims (6)

A heat sink installed on a circuit board including a plurality of electronic components,
The heat sink is composed of a conductive rectangular plate-like member, and is installed on the circuit board in a state where its main surface is electrically grounded at a position that blocks the air flow formed on the circuit board.
Of the contact portion in contact with the circuit board on the main surface and the separated portion separated from the circuit board, the separated portion is divided into two regions by a straight line extending in a direction away from the circuit board,
A heat sink, wherein one of the two regions is bent toward the downstream side of the air flow with the straight line as a fulcrum.   2. The heat sink according to claim 1, wherein a range of the region to be bent at the main surface is set according to a region where the electronic component is disposed downstream of the air flow from the heat sink. .   The heat sink according to claim 1 or 2, wherein the heat sink is installed at a position close to an electronic component having a predetermined amount or more of noise generated during operation.   The heat sink according to any one of claims 1 to 3, wherein an angle at which the region is bent is set so that the region to be bent is parallel to a main flow direction of the air flow.   The heat sink according to any one of claims 1 to 4, wherein the contact portion is not bent and is in contact with a linear region in the circuit board. A plurality of electronic components disposed on the circuit board;
A heat sink according to any one of claims 1 to 5,
At least some of the plurality of electronic components are disposed on the airflow;
The said heat sink is a circuit board arrange | positioned in the upstream of the electronic component arrange | positioned on the said air flow.