JP6221868B2 - Electronic module heat dissipation device - Google Patents

Description

  The present invention relates to an electronic module, and more particularly to a heat dissipation device for an electronic module that can be inserted into and removed from a circuit board.

  Various electronic circuits are used in industrial equipment such as communication equipment, and the electronic circuits are composed of various electronic modules. In general, since an electronic module generates heat when used (energized), it is necessary to consider a heat dissipation structure when designing the electronic module. In particular, in an electronic module that can be inserted into and removed from a circuit board, such as an optical transceiver, for example, it is necessary to consider the insertion and removal method when examining the heat dissipation structure.

  In Patent Document 1, a contact surface between the heat sink and the transceiver housing is formed as an inclined surface, and a heat conductive sheet is attached to any one of the contact surfaces, and the contact surface at the final insertion position of the transceiver housing. An optical transceiver heat dissipating device is disclosed.

Patent No.4998249

  In order to efficiently dissipate the heat generated from the electronic module, it is desirable that there is no portion with low thermal conductivity in the middle of the heat dissipation path. For example, when an air layer exists between an electronic module that is a heat source and a heat sink that is a heat dissipation member, the heat dissipation path from the electronic module to the heat sink is blocked by the air layer, and heat cannot be radiated with high efficiency. .

  Moreover, when making a heat sink and an electronic module contact, it is desirable that the area where a heat sink and an electronic module contact is large. Specifically, a heat sink and an electronic module are not strictly flat surfaces. Therefore, even if both are brought into direct contact, strictly speaking, they are not in surface contact but in contact with a large number of points. In order to increase the contact area between the two, for example, it is conceivable to place a soft heat conductive sheet on the contact surface.

  However, the heat conductive sheet slides when the electronic module is inserted and removed due to its soft characteristics, and is damaged and dropped off. Therefore, it is difficult to use the heat conductive sheet for the contact surface in consideration of the insertion / extraction. Also, it is difficult to achieve good surface contact by direct contact between the module and the heat sink.

  Moreover, in patent document 1, since the upper surface of a transceiver housing | casing is inclined, the component mounting volume of a transceiver is restrict | limited, For example, the height of a component will be restrict | limited.

  The present invention has been made in view of the above points, and an object of the present invention is to provide an electronic module heat dissipation device capable of easily securing a heat dissipation path of an electronic module that can be inserted and removed. It is another object of the present invention to provide an electronic module heat dissipation device capable of forming a good heat dissipation path without sacrificing the mounting area of the module and without directly contacting the module and the heat dissipation member.

  The heat dissipating device for an electronic module according to the present invention includes a substrate, a cage provided on the substrate, having an opening at the top, and accommodating the electronic module from the side so that the electronic module can be inserted and removed, and fixed to the top of the cage. A heat sink having a bottom exposed in the cage, a fixed end fixed to the bottom of the heat sink via a heat conductive sheet, and a free end bent inward in the cage by the bent portion. It is characterized in that it sometimes has a leaf spring whose free end abuts against the upper surface of the electronic module via a heat conductive sheet.

(A) is a perspective view of the heat dissipation apparatus of the electronic module which concerns on Example 1, (b) is a top view of the heat dissipation apparatus of the electronic module which concerns on Example 1. FIG. (A) is sectional drawing of the thermal radiation apparatus of the electronic module which concerns on Example 1, (b) is a figure which shows the thermal radiation path | route in the thermal radiation apparatus of the electronic module which concerns on Example 1. FIG. It is sectional drawing which shows the structure of the leaf | plate spring and heat conductive sheet in the thermal radiation apparatus of the electronic module which concerns on Example 1. FIG. (A), (b) and (c) are sectional views showing the state of the heat dissipation device when the electronic module is not inserted, when it is inserted and removed, and when it is housed, respectively.

  Examples of the present invention will be described in detail below.

  FIG. 1A is a perspective view of a heat dissipation device (hereinafter simply referred to as a heat dissipation device) 10 for an electronic module according to the first embodiment. FIG. 1B is a top view of the heat dissipation device 10. 1A and 1B show the heat dissipation device 10 in a state where an electronic module (hereinafter simply referred to as a module) 20 is inserted. The module 20 is, for example, an optical transceiver.

  The heat dissipation device 10 includes a substrate 11 on which wiring (not shown) is provided, and a metal cage 12 provided on the substrate 11. The cage 12 accommodates the module 20 so that it can be inserted and removed from its side. A heat sink 13 having heat radiating fins is provided on the upper surface of the cage 12. In FIG. 1B, illustration of the radiation fins of the heat sink 13 is omitted for clarity of illustration. The heat sink 13 is made of a metal material having a high thermal conductivity such as aluminum or copper. The heat sink 13 is fixed to the upper surface of the cage by, for example, a thermally conductive tape or clip (not shown).

  The cage 12 has an opening 12AP at the top thereof (see FIG. 1B). The heat sink 13 has a bottom portion (hereinafter also referred to as an exposed bottom portion) 13BP exposed in the cage 12 from the opening 12AP of the cage 12.

  The heat dissipation device 10 includes a leaf spring 14 that physically connects the heat sink 13 and the module 20 when the module 20 is accommodated. The leaf spring 14 is fixed to the bottom 13BP exposed in the cage 12 of the heat sink 13 at one end thereof. Further, the other end of the leaf spring 14 is bent in the cage 12 and abuts against the upper surface of the module 20 when the module 20 is accommodated. The leaf spring 14 functions as a heat conducting member that transfers heat generated from the module 20 to the heat sink 13. The leaf spring 14 is made of a metal material having a large thermal conductivity, such as copper or a copper alloy.

  As shown in FIG. 1B, the leaf spring 14 includes a cage inner region 14IR that is a region provided in the cage 12, and a protruding region 14PJ that is a region protruding from the cage 12 toward the insertion region of the module 20. And have. The protruding region 14PJ of the leaf spring 14 functions as a portion that applies a force that bends the leaf spring 14 toward the heat sink 13 when the module 20 is inserted and removed. Further, the exposed bottom portion 13BP of the heat sink 13 (that is, the opening portion 12AP of the cage 12) is formed so as to surround the cage inner region 14IR of the leaf spring 14 when viewed from the direction perpendicular to the substrate 11.

  FIG. 2A is a cross-sectional view taken along line VV in FIG. 1B and is a cross-sectional view showing the structure of the heat dissipation device 10. FIG. 2B is a diagram illustrating a heat dissipation path in the heat dissipation device 10. 2A and 2B show the heat dissipation device 10 in a state where the module 20 is inserted. Note that FIG. 2B is a cross-sectional view similar to FIG. 2A, but some hatching is omitted for clarity of illustration, and some components are indicated by broken lines. Show.

  As shown in FIG. 2A, a connector CN connected to the wiring of the substrate 11 is provided in the cage 12. The connector CN has a function of fixing the module 20 in the cage 12 when the module 20 is accommodated. Also, the module 20 is energized by connecting a plug (not shown) of the module 20 to the connector CN. For example, when the module 20 is an optical transceiver, communication (signal transmission / reception) is established between the optical transceiver and a host device (not shown).

  The leaf spring 14 has a fixed end portion 14A fixed to the exposed bottom portion 13BP of the heat sink 13 via a heat conductive sheet 15, and a free end portion 14B bent inward in the cage 12 by a bent portion. The free end portion 14 </ b> B of the leaf spring 14 abuts on the upper surface of the module 20 via the heat conductive sheet 16 when the module 20 is accommodated. The heat conductive sheets 15 and 16 can be formed using, for example, silicon or an acrylic material. Accordingly, as shown in FIG. 2B, a heat dissipation path TP from the module 20 to the heat sink 13 is formed via the heat conductive sheet 16, the leaf spring 14, and the heat conductive sheet 15. All the heat radiation paths TP are formed of a heat conductive member, and for example, no air layer is interposed. Therefore, it is possible to ensure a good heat dissipation path.

  In the present embodiment, the exposed bottom portion 13BP of the heat sink 13 is provided so as to surround the cage inner region 14IR of the leaf spring 14 in a top view. That is, in the cage 12, the heat sink 13 is exposed over the entire plate spring 14. In other words, the entire in-cage region 14IR of the leaf spring 14 faces the exposed bottom portion 13BP of the heat sink 13. Accordingly, not only the fixed end portion 14A of the leaf spring 14, that is, the heat dissipation path TP to the heat sink 13 via the heat conductive sheet 15, but also assistance to the heat sink 13 via the free end portion 14B in some cage internal regions 14IR. A typical heat dissipation path STP is formed. Therefore, heat can be radiated with higher efficiency.

  Further, the portion of the fixed end portion 14A that contacts the heat sink 13 and the portion of the free end portion 14B that contacts the module 20 are formed as a flat surface, and are preferably in contact with each other with uniform pressure in the contact surface. . For example, if the contact pressure varies within the contact surface of the fixed end 14 </ b> A with the heat sink 13, the surface contact is partially lost, or a gap is partially formed at the contact interface between the heat conductive sheet, the leaf spring 14, and the heat sink 13. This is because there is a possibility that the heat radiation path may be hindered.

  FIG. 3 is a cross-sectional view showing the detailed structure of the leaf spring 14 and the heat conductive sheets 15 and 16. The leaf spring 14 can be formed, for example, by bending or pressing a thin plate metal material. The free end portion 14B of the leaf spring 14 is bent from the fixed end portion 14A toward the inside of the cage 12, that is, toward the substrate 11 by the bent portion BP. The bent portion BP can be configured as, for example, an R-shaped curved portion or an L-shaped refracting portion. Considering the suppression of stress concentration due to repeated raising and lowering operations or elastic motion of the leaf spring 14, it is desirable that the bent portion BP is configured as a curved portion.

  Further, a gripping portion GP that is bent in the direction of the substrate 11 is provided at the protruding region 14PJ of the leaf spring 14, in the present embodiment, at the end opposite to the bent portion BP of the free end portion 14B. The gripping part GP is used to push up the free end part 14B of the leaf spring 14 toward the heat sink 13 when the module 20 is inserted and removed, thereby securing a module 20 insertion / extraction region. The gripping part GP is bent in the direction of the substrate 11 so that it easily engages with a finger when the leaf spring 14 is lifted, and has a function of preventing the module 20 from falling off when it is unintentionally detached from the connector. It is possible to have it.

  The heat conductive sheet 15 provided at the fixed end of the leaf spring 14 has a structure in which a base material 15B is sandwiched between adhesive materials 15A and 15C. Therefore, the leaf spring 14 and the heat sink 13 are fixed by the adhesive materials 15A and 15C. The heat conductive sheet 16 provided at the free end 14 of the leaf spring 14 has a structure in which an adhesive material 16A and a base material 16B are laminated from the leaf spring 14 side. The heat conductive sheet 16 is affixed to the leaf spring 14. Therefore, the heat conductive sheet 16 is not provided with an adhesive on the side in contact with the module 20, and the free end portion 14 </ b> B can be easily separated (detached) from the module 20 together with the heat conductive sheet 16. It has become.

  Next, the insertion / extraction procedure of the module 20 is demonstrated using FIG. 4 (a) thru | or (c). FIG. 4A shows the heat dissipation device 10 when the module 20 is not accommodated. In a state where the module 20 is not housed in the cage 12, the fixed end portion 14 </ b> A of the leaf spring 14 is fixed to the heat sink 13 via the heat conductive sheet 15, and the free end portion 14 </ b> B is between the cage 12 and the substrate 11. And no-load state (the state where the elastic force is not working) is maintained. When inserting the module 20, an upward force is applied to the free end portion 14 </ b> B using the grip portion GP to lift the free end portion 14 </ b> B to a height equal to or higher than the height of the module 20.

  FIG. 4B shows a state in which the module 20 is inserted with the free end portion 14B lifted. When lifting the free end portion 14B, the free end portion 14B performs an elastic motion with the bent portion BP as a fulcrum. As shown in FIG. 4B, the leaf spring 14 does not contact the module 20 during insertion. When the force applied to the free end portion 14B is released in this state, as shown in FIG. 4C, the free end portion 14B comes into contact with the upper surface of the module 20 via the heat conductive sheet 16 and enters a housed state. . When the module 20 is housed, the elastic force remaining in the free end portion 14B works in the direction of the module 20. Therefore, the contact area between the free end portion 14B and the module 20 can be secured (maintained).

  When the module 20 is removed from the cage 12, first, the free end portion 14B is lifted to separate the free end portion 14B from the module 20, as shown in FIG. Then, the module 20 is removed, the force applied to the free end portion 14B is released, and the state shown in FIG. Therefore, the heat conductive sheet 16 does not slide on the upper surface of the module 20 even when it is removed.

  As described above, in this embodiment, the plate spring is used as a heat conduction member and an insertion / extraction member, and the function as the heat conduction member is reinforced by the heat conduction sheet. Therefore, the heat radiation path can be formed reliably, and the heat radiation efficiency is greatly improved. In addition, taking advantage of the increased contact area, which is an advantage of the heat conductive sheet, and breakage during sliding, which is a drawback of the heat conductive sheet, can be eliminated. Further, the module mounting volume and height are not limited by the heat dissipation device, and the module can be designed with the upper limit of the standard.

DESCRIPTION OF SYMBOLS 10 Heat radiation apparatus 11 Board | substrate 12 Cage 13 Heat sink 14 Leaf spring 14A Fixed end part 14B Free end part 14IR Cage in area | region 14PJ Protrusion area | region 15 Thermal conductive sheet 16 Thermal conductive sheet BP Bending part GP Gripping part

Claims (6)

A substrate,
A cage that is provided on the substrate, has an opening at the top, and accommodates an electronic module in a freely insertable / removable manner from the side;
A heat sink having a bottom fixed to the top of the cage and exposed from the opening into the cage;
The heat sink has a fixed end fixed to the bottom of the heat sink via a heat conductive sheet and a free end bent to the inside of the cage by a bent portion, and the free end is thermally conductive when the electronic module is accommodated. And a leaf spring that abuts against the upper surface of the electronic module via a sheet. The leaf spring has a cage inner region that is a region provided in the cage, and a protruding region that is a region protruding from the cage,
The heat dissipation device according to claim 1, wherein a grip portion bent toward the substrate is provided in the protruding region.   The heat radiating device according to claim 1, wherein a connector for fixing the electronic module when the electronic module is accommodated is provided in the cage.   The heat radiating device according to claim 1, wherein the leaf spring is made of copper or a copper alloy.   The heat dissipating device according to claim 1, wherein the electronic module is an optical transceiver.   6. The exposed bottom portion of the heat sink is formed so as to surround the cage inner region of the leaf spring as a whole when viewed from a direction perpendicular to the substrate. The heat dissipation apparatus as described in any one.

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