Electronic device and assembly method

Abstract

To provide a technique capable of preventing the deformation or the like of a substrate by reducing a load and a force to the substrate due to a heat sink, in the technique of an electronic apparatus including the heat sink.SOLUTION: An electronic apparatus 1 includes a case which has a first case 11 and a second case 12, a substrate 2 which is stored in the case, has a heat generating component 5, and is arranged so that a main surface extends in a first direction, and a heat sink 3 which is stored in the case, is arranged to contact the heat generating component 5 through a heat dissipation grease, and is for dissipating the heat of the heat generating component 5. The heat sink 3 is fixed to the substrate 2 through an elastic body in a second direction perpendicular to the first direction, so as to press the heat generating component 5, a heat generating component area in the substrate 2 is arranged with a space from the second case 12 in the second direction, and the case includes a support part 4 which is projected toward the heat sink 3 and supports the heat sink 3, so as to reduce the load acting on the substrate 2 by the weight of the heat sink 3.SELECTED DRAWING: Figure 3

Description

Technical Field

[0001] The present invention relates to the technology of electronic devices having heat sinks.

Background Art

[0002] Conventional various electronic devices are for the purpose of improving the cooling performance of heat-generating components (in other words, components that require heat dissipation) such as semiconductor devices mounted on an electronic circuit board (such as a printed circuit board, sometimes referred to as a substrate). A heat sink is attached to the heat-generating component and used.

[0003] Inside the case (in other words, the housing) of the electronic device, a substrate and a heat sink are housed. In the case of the natural air cooling method, the case is provided with ventilation holes for passing air. Conventionally, the heat sink is fixed to the substrate, for example, by screw fastening.

[0004] As a prior art example, International Publication No. 2008 / 139563 (Patent Document 1) can be cited. In Patent Document 1, for example, as shown in FIG. 2, in a cross section of the electronic device 100, a printed circuit board 120 and the like are mounted inside the housing 210. A heat sink 150 is provided for the semiconductor component 110 of the printed circuit board (wiring board) 120. The heat sink 150 is fixed to the printed circuit board 120 by screws 156, washers 157, and springs 158. Patent Document 1 describes that it has a load reduction part 130 that maintains the distance between the semiconductor component 110 and the printed circuit board 120 and reduces the load applied to the bumps 117 of the semiconductor component 110.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0006] In the above-mentioned electronic device, it is common for the heat sink to become larger in order to secure a surface area for heat dissipation as the amount of heat generated by the heat-generating component increases. The larger the heat sink becomes, the heavier it is. The heavier the heat sink becomes, the greater the load (in other words, the force applied to the substrate) on the substrate increases. As a result, there is a risk of leading to deformation or breakage of the substrate. When the substrate is deformed due to the weight of the heat sink, as an influence of this deformation, there is also a risk of, for example, cracks occurring in components (such as the solder of surface-mounted components) mounted in the vicinity of the heat sink.

[0007] In a conventionally common heat sink fixing structure, the heat sink is fixed so as to be pressed against the substrate with a pressing force equal to or greater than a certain level by screw fastening or the like. Thereby, the heat dissipation and cooling performance by the heat sink is enhanced. However, in the heat sink fixing structure in which a large heat sink is directly attached to the substrate as described above, it is necessary to fix it with a strong pressing force corresponding to the weight of the heat sink, and due to that pressing force, a large load is applied to the fixing portion of the substrate, which may cause deformation of the substrate.

[0008] Also, the above heat sink fixing structure needs to be mounted in a space as narrow as possible with respect to the mounting area of the heat-generating component in the space inside the case.

[0009] There is a need for a structure that can secure or improve the heat dissipation and cooling performance by the above heat sink, reduce the load and force on the substrate by the above heat sink, and prevent deformation of the substrate.

[0010] Also, as for the arrangement (in other words, the installation form) of the case of the electronic device, there are vertical placement and horizontal placement. There are also electronic devices that can be used in either the vertical placement or the horizontal placement installation form. Depending on the installation form, a structure that can reduce the load and force on the substrate by the above heat sink is required.

[0011] An object of the present invention is to provide a technology related to an electronic device having a heat sink, which can reduce the load and force on a substrate by the heat sink and prevent deformation of the substrate and the like.

Means for Solving the Problems

[0012] A typical embodiment of the present invention has the following configuration. The electronic device of the embodiment includes a case having a first case and a second case, a substrate housed in the case, having heat-generating components, and arranged such that a main surface extends in a first direction, and a heat sink housed in the case and arranged to be in contact with the heat-generating components via heat-dissipating grease for dissipating heat from the heat-generating components. The heat sink is fixed to the substrate via an elastic body in a second direction perpendicular to the first direction so as to press the heat-generating components. A heat-generating component region having the heat-generating components on the substrate is arranged with a space provided between the second case in the second direction. The case has a support portion that protrudes toward the heat sink and supports the heat sink so as to reduce the load acting on the substrate due to the load of the heat sink.

Effects of the Invention

[0013] According to a typical embodiment of the present invention, regarding the technology of an electronic device having a heat sink, it is possible to reduce the load and force on a substrate by the heat sink and prevent deformation of the substrate and the like. Other problems, configurations, effects, etc. than those described above are shown in the embodiments for carrying out the invention.

Brief Description of the Drawings

[0014]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Figure 6

Figure 7

Figure 8

Figure 9

Figure 10

Figure 11

Figure 12

Figure 13

Figure 14

Figure 15

Figure 16

Figure 17

Figure 18

Figure 19

Best Mode for Carrying Out the Invention

[0015] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In the drawings, the same components are generally denoted by the same reference numerals, and repeated descriptions are omitted. In the drawings, the representation of each component may not represent the actual position, size, shape, range, etc. in order to facilitate understanding of the invention.

[0016] <Embodiment 1> The electronic device 1 according to Embodiment 1 of the present invention will be described with reference to FIGS. 1 to 19.

[0017] The electronic device 1 according to Embodiment 1 is, for example, an optical network device, and the heat-generating component 5 on which the heat sink 3 is mounted is, for example, an optical module. Of course, the present invention is not limited to this and is applicable. The optical module is an ONU (Optical Network Unit) having a function of converting light and electricity, and is susceptible to heat, so it is a target for heat dissipation and cooling by the heat sink 3.

[0018] The electronic device 1 according to Embodiment 1 can be used in either a vertical or horizontal installation form as shown in the drawings (FIGS. 1 and 2) when used by a user. The user uses the electronic device 1 in a desired arrangement. The electronic device 1 according to Embodiment 1 has a structure that can reduce the load on the substrate 2 (FIG. 3, etc.) by the heat sink 3 in any installation form.

[0019] Specifically, as will be described later, this structure is a combination of a support structure in which the heat sink 3 is supported by a support portion 4 (FIG. 3, etc.) provided on the case and a fixing structure in which the heat sink 3 is fixed to the substrate 2 via an elastic body.

[0020] In the electronic device 1 of Embodiment 1, in a case that houses a substrate 2, a heat sink 3, etc., a support portion 4 for supporting the heat sink 3 is provided. The support portion 4 is a rib that extends toward the heat sink 3. The electronic device 1 has a support structure in which the heat sink 3 is supported by the support portion 4 of this case. Thereby, since the load of the heat sink 3 is received by the support portion 4, a structure is formed in which the load from the heat sink 3 is not directly applied to the substrate 2.

[0021] Further, as a fixing structure of the heat sink 3 to the substrate 2 in the electronic device 1 of Embodiment 1, the heat sink 3 (particularly the convex portion) is fixed to the substrate 2 by a fixing screw 7 via an elastic body (the wave washer 6 in FIG. 3). In this heat sink fixing structure, the contact surface between the heat generating component 5 and the heat sink 3 is brought into contact via the heat dissipation grease 9, and the heat sink 3 is fixed so as to be pressed against the substrate 2 with a pressing force within a predetermined range. Also, a space is provided on the other side of the substrate 2 with respect to the one side on which the heat sink 3 is mounted so that the substrate 2 (particularly the heat generating component region 22 in FIG. 7) does not contact the second case 12 (FIG. 16, etc.). With this heat sink fixing structure, the substrate 2 and the heat sink 3 can be fixed in a space-saving manner in the case, and a ventilation space is also secured in a wider space, thereby enhancing the cooling performance by the heat sink 3.

[0022] Then, due to the interaction between the heat sink fixing structure and the heat sink support structure in which the heat sink 3 is supported by the support portion 4 of the case in the electronic device 1 of Embodiment 1, in any installation form, the load / force on the substrate 2 due to the weight of the heat sink 3 can be reduced, and deformation of the substrate 2, etc. can be prevented.

[0023] In the electronic device 1 of Embodiment 1, as a structure capable of corresponding to both vertical and horizontal installation forms, support portions 4 are provided on the entire circumference of the region where the heat sink 3 is arranged in the case (the first case 11 and the second case 12). The support portions 4 are provided corresponding to at least one location on each of the four sides of the main surface of the heat sink 3 (the surface that appears to have the largest area when viewed in plan). The support portions 4 are provided so as to have a predetermined clearance from the heat sink 3. Thereby, the electronic device 1 can reduce the load and force on the substrate 2 by the heat sink 3 regardless of whether it is used in a vertical or horizontal installation form.

[0024] [Electronic device - Vertical placement] FIG. 1 shows a perspective view of the appearance of the electronic device 1 of Embodiment 1 in a vertically placed state as an arrangement (installation form). For the sake of explanation, the coordinate system and directions of the actual space where the electronic device 1 is installed may be (X, Y, Z). The X-axis is the first horizontal direction, the Y-axis is the second horizontal direction, and the Z-axis is the vertical direction. In the case of FIG. 1, the X-axis corresponds to the width direction, thickness direction, left-right direction of the case, the Y-axis corresponds to the depth direction, front-back direction, and the Z-axis corresponds to the height direction, up-down direction.

[0025] The case (in other words, the housing) of the electronic device 1 is roughly composed of a first case 11 and a second case 12. The first case 11 and the second case 12 are separated left and right in the X direction. The first case 11 is a main case with a large storage volume, and the second case 12 is a cover with a smaller storage volume than the first case 11. In FIG. 1, the first case 11 is on the left hand side and the second case 12 is on the right hand side. The first case 11 constitutes the left side surface of the case, and the second case 12 constitutes the right side surface.

[0026] The front portion 13 of the electronic device 1 and the case has an elongated region in the Z direction. Although simplified in the drawing, the front portion 13 is provided with input / output terminals, buttons, LEDs, etc. as a user interface according to the electronic device. On the rear portion, which is on the opposite side of the front portion 13 and not visible in FIG. 1, power terminals, buttons, etc. according to the electronic device are provided.

[0027] The outer peripheries of the four sides of the main surfaces (the surfaces that appear to have the largest area when viewed in plan view) of the first case 11 and the second case 12 are joined by the front portion 13, the rear portion, the upper surface portion 14, and the lower surface portion on the opposite side thereof, respectively. Note that a lower surface portion not visible in the drawings is disposed on the installation surface of the electronic device 1. Further, although not shown, a stand for stably arranging the electronic device 1 in a vertical position may be provided as an additional component on the lower surface portion of the electronic device 1.

[0028] In the drawings, the case is shown in a simplified manner. In the actual case, in order to air-cool the heat sink 3 by a natural air-cooling method, holes (vent holes) through which air passes and the like are provided. The configuration such as the shape of the vent holes is not particularly limited.

[0029] The region indicated by the dashed line in the case shows a schematic region where the heat sink 3 described later is disposed. In the case of the vertical arrangement in FIG. 1, the heat sink 3 and heat-generating components 5 of the substrate 2 described later (FIG. 3 etc.) are disposed at the lower part in the case. Considering that the metal heat sink 3 among the components of the electronic device 1 is the heaviest and the heat dissipation performance of the heat sink 3 by the natural air-cooling method, such an arrangement of the components is adopted.

[0030] [Electronic device - horizontal placement] FIG. 2 shows a perspective view of the appearance of the electronic device 1 according to Embodiment 1 in a horizontal placement state (installation form). In this horizontal placement state, the second case 12 in FIG. 1 becomes the lower surface portion and is disposed on the installation surface of the electronic device 1, and the first case 11 in FIG. 1 becomes the upper surface portion and is disposed. The upper surface portion 14 in FIG. 1 becomes the right side surface portion and is disposed in FIG. 2. Note that hereinafter, mainly the coordinate system and terms in the vertical arrangement in FIG. 1 will be used for description. In the case of horizontal placement, it is only necessary to consider that the relative relationship changes with respect to the vertical arrangement, and the same repetitive description will be omitted.

[0031] Note that the direction in which the main surface (the surface that appears to have the largest area in plan view) of the substrate 2 (FIG. 3) extends (particularly the longitudinal direction) is defined as the first direction, and the direction perpendicular to the first direction is defined as the second direction. In the case of the vertical orientation in FIG. 1, the first direction is the vertical direction and the second direction is the horizontal direction. In the case of the horizontal orientation in FIG. 2, the first direction is the horizontal direction and the second direction is the vertical direction.

[0032] [Electronic device - disassembly] FIG. 3 shows a perspective view of the vertically oriented electronic device 1 of Embodiment 1 in a state where it is disassembled into main components, with the same coordinate system (X, Y, Z) as in FIG. 1. In FIG. 3, the components of the electronic device 1, in order from the left, include a first case 11, a heat sink 3, a substrate 2, and a second case 12. On the inner surface of the first case 11, support portions 4 (a plurality of ribs) and the like are provided. A heat dissipation grease 9 is applied to the heat sink 3. The substrate 2 is an electronic circuit board, and heat generating components 5 are mounted in a part of the lower region (the left side surface). Support portions 4 are also provided on the inner surface of the second case 11 that is not visible (FIG. 15 described later).

[0033] [Assembly method] FIG. 4 is a flowchart schematically showing the assembly method of the electronic device 1 of Embodiment 1. The flowchart of FIG. 4 corresponds to the assembly work flow of the electronic device 1 by an operator and has steps S1, S2, and S3. Step S1 is the first step of attaching the heat sink 3 to the support portion 4 of the first case 11. Step S2 is the second step of fixing the substrate 2 to the first case 11 and the heat sink 3. Step S3 is the third step of attaching the second case 12 to the first case 11.

[0034] In step S1, the operator attaches the heat sink 3 by placing it in the region formed by the plurality of support portions 4 in the space on the inner surface of the first case 11 (FIGS. 3, 5, 6, 8, 9, etc.). The heat sink 3 has a predetermined clearance (a distance with a margin) from the support portion 4.

[0035] In step S2, the operator attaches the substrate 2 to the first case 11 and the heat sink 3 (see FIGS. 7, 11, 13, etc.). At this time, heat dissipation grease 9 is applied to a predetermined location of the heat sink 3. The substrate 2 is arranged so that the heat generating component 5 contacts the area of the heat dissipation grease 9 of the heat sink 3. The substrate 2 is aligned and arranged with respect to the positioning pins 8 of the first case 11. The heat dissipation grease 9 is a member that promotes heat conduction of the contact surface. Also, at this time, the holes 25 of the substrate 2 are aligned with the screw holes 33 of the convex portions (see FIG. 10, etc.) of the heat sink 3, and through the wave washer 6, they are screwed and fastened with the fixing screw 7 (see FIG. 19, etc.). Thereby, the heat sink 3 is fixed to the substrate 2 in a state where it is pressed against the heat generating component 5 with a pressing force equal to or greater than a predetermined value.

[0036] In step S3, the operator fixes the second case 12 to the first case 11 in which each part including the heat sink 3 and the substrate 2 is housed and attached, by screw fastening (see FIG. 14, etc.). Specifically, through the screw holes of the four corner positioning pins 111 of the first case 11, the three corner holes 26 of the substrate 2, and the four corner holes 121 of the second case 12, it is fixed with the screw 122 (see FIG. 3, etc.). In Embodiment 1, the fixing of the first case 11 and the second case 12 is by snap fitting on the four sides (front and rear surfaces and upper and lower surfaces) and screw fastening at the corners.

[0037] At the lower part of FIG. 4, as a comparative example for Embodiment 1, the flow of a conventionally general assembly method is shown, which has steps S11, S12, and S13. In step S11, the operator attaches the heat sink to the substrate. The heat sink is fixed to the heat generating component of the substrate by screw fastening. The operator holds the substrate with the heat sink attached (also referred to as a substrate with a heat sink) and performs subsequent operations. In step S12, the operator attaches the substrate with the heat sink to the first case. In step S13, the operator fixes the second case to the first case with the substrate with the heat sink attached. Note that in other methods, the substrate may be attached to the second case in step S12, and the first case may be fixed to the second case in step S13.

[0038] In the flow of the comparative example, there is a time when an operator performs work while holding a substrate with a heat sink. In the whole work, this time becomes relatively long. During this time, a load / force due to the load of the heat sink acts on the substrate. As a result, deformation of the substrate or the like may occur.

[0039] On the other hand, according to the flow of the assembly method of Embodiment 1, after the heat sink 3 is attached to the support portion 4 of the first case 11 in step S1, the substrate 2 is attached to the heat sink 3 in step S2. As a result, there is no time when an operator performs work while holding a substrate with a heat sink. Or, even if that time occurs, it is shorter than the time of the comparative example. Further, in Embodiment 1, the heat sink 3 is stably arranged with respect to the substrate 2 by a structure combining a support structure by the support portion 4 and a fixing structure by fixing screws 7 or the like. As a result, in Embodiment 1, the influence of the load / force applied to the substrate 2 due to the load of the heat sink 3 is reduced. By the assembly method of Embodiment 1, the load on the substrate 2 by the heat sink 3 can be suppressed even during the manufacturing work, and deformation of the substrate 2 or the like can be prevented.

[0040] [First case, support portion] FIG. 5 shows a structural example of the support portion 4 and the like on the inner surface of the first case 11 in a plan view of the Y-Z plane. In the space on the inner surface of the first case 11, a plurality of support portions 4 are provided at the lower part in the Z direction, and a region 400 surrounded by these plurality of support portions 4 is provided as a region for arranging the heat sink 3. The region 400 is roughly rectangular. The support portion 4 projects in the X direction from the inner surface of the first case 11 toward the heat sink 3.

[0041] Around the region 400, positioning pins 8 and 111 are also provided at predetermined positions. In this example, it has three positioning pins (8, 111). The positioning pin 8 also has a rib portion protruding around from the shaft portion, and the rib portion also functions as the support portion 4 as will be described later (FIG. 12).

[0042] In the region of the inner surface of the first case 11, positioning pins 111 for positioning and fixing the substrate 2 and the second case 12 are provided at predetermined positions near the four corners. In particular, the positioning pins 111 are provided with screw holes.

[0043] For each of the four sides of the heat sink 3 (Fig. 6) arranged in the region 400, at least one support portion 4 (including positioning pins 8 etc.) is provided on each side. Thereby, the electronic device 1 of the first embodiment can cope with both vertical and horizontal installation forms. That is, no matter in which arrangement it is used, the load on the substrate 2 by the heat sink 3 can be supported and reduced by at least one of the support portions 4.

[0044] Fig. 6 shows a state in which the heat sink 3 is arranged in the region 400 by the support portion 4 of the first case 11 in Fig. 5. In the Y-Z plane, the heat sink 3 has a rectangular main surface as shown in the figure, and for each of the four sides of the main surface (the upper and lower sides in the Z direction and the front and rear sides in the Y direction), at least one location is supported by the support portion 4. In this example, the upper side is supported by three support portions 4. The lower side is supported by three support portions 4. The right side (the rear side in the Y direction) is supported by the rib portions of the positioning pins 8, 111. The left side (the front side in the Y direction) is supported by the rib portions of the support portion 4 and the positioning pin 111. The heat sink 3 is arranged with a predetermined clearance from the support portion 4.

[0045] [Substrate] Fig. 7 shows a state in which the substrate 2 is attached to the first case 11 in which the heat sink 3 of Fig. 6 is arranged. The holes 26 at the corners of the substrate 2 are aligned with the positioning pins 111 at the corners of the first case 11. Also, the holes 25 (Fig. 3) in the heat generating component region 22 of the substrate 2 are aligned with the screw holes 33 of the convex portions of the heat sink 3. Screw fastening is performed with the fixing screw 7 through the wave washer 6 to the screw holes 33.

[0046] The substrate 2, in terms of its Y-Z plane configuration, has a heat-generating component region 22 that extends from the main substrate region with the largest area to about the lower left half region. A light module, which is a heat-generating component 5, is mounted on the heat-generating component region 22 (left side surface). A part of the heat-generating component region 22 is notched, and a part of the heat-generating component 5 is exposed.

[0047] The right side (about the right half region) of the heat-generating component region 22 is a notch region 23, and the heat sink 3 is exposed. This notch region 23 is a region through which air passes in the natural air cooling method.

[0048] The lower part of FIG. 7 shows an enlarged view of the heat-generating component region 22 of the substrate 2. The heat-generating component region 22 is connected to the main substrate region via a bridge-shaped connection region 24. An opening region 27 is provided near the connection region 24. The opening region 27 is provided by making a hole in a part of the substrate 2. In this way, the heat-generating component region 22 is provided in a shape that extends outward (downward in the Z direction) from the main substrate region via the connection region 24 and the opening region 27. The heat conducted through the substrate 2 can be blocked (in other words, heat conduction can be reduced) by the connection region 24 and the opening region 27. Thus, the heat transferred from the main substrate region to the heat-generating component region 22 or the heat transferred from the heat-generating component region 22 to the main substrate region can be blocked.

[0049] Also, the opening region 27, together with the notch region 23, serves as a passage for air in the X direction, so the cooling efficiency of the heat sink 3 can be increased. In particular, when the electronic device 1 is installed horizontally (FIG. 2), this opening region 27, together with the notch region 23, serves as a passage for air, so the cooling efficiency of the heat sink 3 can be increased.

[0050] In addition, due to the load of the heat sink 3, a load and force may act on the heat-generating component region 22 in the X direction. In this case, in the first embodiment, since the heat-generating component region 22 has the connection region 24 and the opening region 27, and there is a gap (FIG. 16 described later) between the heat-generating component region 22 and the second case 12, it can move to a certain extent in the X direction. As a result, the load and force on the substrate 2 caused by the heat sink 3 can be released, and in particular, deformation near the heat-generating component region 22 can be prevented or reduced.

[0051] [Attachment of Heat Sink to Support Portion] FIG. 8 shows details of the attachment of the heat sink 3 to the region 400 (FIG. 5) of the support portion 4 of the first case 11. The heat sink 3 is arranged along a plurality of support portions 4 provided on the inner surface of the first case 11. Since there is a predetermined clearance between the support portion 4 and the four sides of the heat sink 3, the arrangement and attachment of the heat sink 3 to the region 400 are not completely fixed, and the heat sink 3 becomes semi-fixed with a certain movable distance corresponding to the clearance.

[0052] The support portion 4 is arranged with a predetermined clearance with respect to each surface of the four sides (upper and lower sides, front and rear sides) of the main surface of the heat sink 3 (specifically, FIGS. 16 and 17 described later). When in the vertically placed state, due to gravity, the degree to which the lower surface of the heat sink 3 in the Z direction is supported by the support portion 4 increases.

[0053] FIG. 9 shows a state in which the heat sink 3 is attached to the region 400 (FIG. 5) of the support portion 4 of the first case 11. As shown in the figure, the four sides (outer periphery) of the main surface of the heat sink 3 are supported so as to be surrounded from the outside by the support portion 4.

[0054] After the heat sink 3 is attached to the region 400, heat dissipation grease 9 (FIG. 3) is applied to a part of the region of the heat sink 3, the region 360 in FIG. 9. In the assembly method of the first embodiment, the heat dissipation grease 9 is applied to the heat sink 3 side, but it is not limited to this, and in other methods, the heat dissipation grease 9 may be applied to the contact surface of the heat-generating component 5.

[0055] [Heat sink] Figure 10 shows a perspective view of the heat sink 3. As shown in the figure, the heat sink 3 has irregularities (concave and convex portions) in the Z direction. In other words, the heat sink 3 has a shape in which a flat metal plate (the flat plate constituting the main surface) is bent into an uneven shape. The right side in the X direction is convex and the left side is concave. The heat sink 3 has convex portions 301 and 302 as two convex portions in the vertical direction, and has concave portions 311, 312, and 313 as three concave portions with the two convex portions interposed therebetween.

[0056] At predetermined positions in the convex portions 301 and 302, screw holes 33 for the fixing screws 7 (Figure 3) are provided. Near the left end of the convex portion 301, there is a screw hole 33. At a position at a predetermined distance from the left end of the convex portion 302, there is a screw hole 33. In the concave portion 312, the region having a diagonal line connecting the two screw holes 33 is the region where the heat-generating component 5 is arranged, and has a region 360 where the heat-dissipating grease 9 is applied.

[0057] The heat sink 3 mainly has a plurality of heat-radiating fins 32 on the left side surface of the uneven flat plate (the surface facing the first case 11). The left side surfaces of the concave portions 311, 312, and 313 have heat-radiating fins 32. Also, the lower concave portion 313 has heat-radiating fins 32 on its right side surface. The heat-radiating fins 32 have a long plate shape extending in the Y direction in this example, and a plurality of heat-radiating fins 32 are arranged in the Z direction. The shape of the heat-radiating fins 32 is not limited to the shape of this example, and may be a pin shape or the like.

[0058] In the first embodiment, the shape of the heat sink 3 is an uneven shape in which the region of the heat-generating component 5 can be surrounded by the convex portions 301 and 302 in the Z direction as shown in the figure. Not limited to this, in a modification, the shape of the heat sink 3 may be a shape provided with unevenness in the Y direction so that the region of the heat-generating component 5 can also be surrounded in the Y direction.

[0059] [Attachment of the substrate to the heat sink] FIG. 11 shows the details of the attachment of the substrate 2 to the heat sink 3 in the first case 11 of FIG. 9. For the positioning pins in the first case 11, for example, the upper right positioning pin 8 and the lower left positioning pin 111 with respect to the heat sink 3, the holes 28 at two corresponding positions on the substrate 2 are aligned. Also, for the two screw holes 33 at the upper left and lower right with respect to the area of the heat dissipation grease 9 of the heat sink 3, the holes 25 at two corresponding positions in the heat generating component area 22 are aligned. Thereby, the heat generating component 5 in the heat generating component area 22 is arranged to contact the heat dissipation grease 9 in the recess 312 of the heat sink 3.

[0060] FIG. 12 shows an example of the detailed structure of the positioning pin 8 in the first case 11. The positioning pin 8 has a cylindrical shaft portion extending in the X direction, and rib portions 84 protrude around the shaft portion in the respective directions of, for example, up and down in the Z direction and front and back in the Y direction. These rib portions 84 each function as a support portion 4. For example, among the four rib portions 84, at least any one of the rib portions 84 may be used as a portion for supporting the heat sink 3. In the example of FIG. 11, the rib portion 84 on the left side of FIG. 12 in the upper right positioning pin 8 supports the right side (the rear side in the Y direction) of the heat sink 3 with a predetermined clearance.

[0061] FIG. 13 shows a state where the substrate 2 is attached to the heat sink 3 in FIG. 11. For the two screw holes 33 on the diagonal of the convex portion 312 (FIG. 10) of the heat sink 3, through the two corresponding holes 25 in the heat generating component area 22, respectively, with a wave washer 6, which is an elastic body, sandwiched therebetween, it is screwed and fastened by a fixing screw 7 (specifically, see FIG. 19 described later). Thereby, the heat sink 3 is fixed to the substrate 2 in a state where a pressing force equal to or greater than a predetermined pressing force is applied to the heat generating component 5. Since this fixing is semi-fixed through an elastic body, the load / force applied to the substrate 2 by the heat sink 3 is suppressed to be within a predetermined range of load / force.

[0062] [Attachment of the Second Case to the First Case] FIG. 14 shows the details of the attachment of the second case 12 to the first case 11 to which the substrate 2 of FIG. 13 is attached. At a position near a corner of the first case 11, a hole 121 at a corresponding position of the second case 12 is aligned with a positioning pin 111 having a screw hole, and is screwed with a screw 122 (FIG. 3). Thereby, the second case 12 is fixed to the first case 11. The side portion (a part constituting the front surface 13 etc.) of the second case 12 is shorter in length in the X direction than the side portion (a part constituting the front surface 13 etc.) of the first case 11.

[0063] In the cutout region 23 (FIG. 7) of the substrate 2, a part of the heat sink 3 is exposed, and this cutout region 23 forms a space for ventilation between the second case 12. Further, corresponding to this ventilation space, ventilation holes (not shown) are provided on the surface of the second case 12. Also, a gap is provided between the heat generating component region 22 and the second case 12 so as not to come into contact (FIG. 16 described later).

[0064] [Support portion of the second case] FIG. 15 shows an example of the structure of the support portion 4 on the inner surface of the second case 12. FIG. 15 is a perspective view of the lower part of the inner surface of the second case 12 seen from the opposite direction in the X direction (from left to right in FIG. 3). In the first embodiment, a plurality of support portions 4 (particularly referred to as support portion 4B) on the second case 12 side are formed at predetermined positions and shapes so as to support not only the vicinity of the four sides of the main surface of the heat sink 3 but also the convex portions 301, 302 (FIG. 10) in the main surface. The support portion 4B protrudes in the X direction from the inner surface of the second case 12 toward the heat sink 3. For example, a certain support portion 4B has a concave shape as shown in the figure so as to support the upper surface, lower surface, and right side surface of the convex portion 301 (FIG. 10) with a predetermined clearance.

[0065] The heat sink 3 disposed within the region 400 of the support portion 4 of the first case 11 is sandwiched by the support portion 4B from the side of the second case 12. As a result, the heat sink 3 is generally disposed at a predetermined position. Strictly speaking, since there is a clearance between each support portion 4 and each surface of the heat sink 3, the heat sink 3 is movable by gravity according to the installation form, and accordingly, the placement position within the placement region is determined.

[0066] [Electronic device - Cross-sectional view] FIG. 16 shows a cross-sectional view in the vertical X-Z plane of the electronic device 1 after assembly. FIG. 16 shows a partial cross-section at the position where the heat-generating component 5 (heat-generating component region 22) is located. In FIG. 16, the cross-sections of two screwing portions of the heat sink 3 are shown together.

[0067] As shown in the figure, the first case 11 has a support portion 4 (specifically, support portion 4A) extending in the X direction (right direction in the drawing) from the base flat plate toward the heat sink 3. In the cross-section of FIG. 16, the upper and lower sides of the heat sink 3 are supported by the support portion 4A. In particular, in the case of vertical placement, corresponding to the gravity in the Z direction, the support portion 4A disposed below the portion that becomes the lower side of the heat sink 3 (for example, the lower side of the recess 313) supports the lower side portion of the heat sink 3 on top of the support portion 4A to receive the load from the heat sink 3.

[0068] As shown in the figure, the second case 12 has a support portion 4 (specifically, support portion 4B) extending in the X direction (left direction in the drawing) from the base flat plate toward the heat sink 3. In the cross-section of FIG. 16, the convex portion 301 of the heat sink 3 is supported by the support portion 4B. Although not shown, similar to the support portion 4A, the support portion 4B disposed below the portion that becomes the lower side of the heat sink 3 supports the lower side portion of the heat sink 3 on top of the support portion 4B to receive the load from the heat sink 3.

[0069] A space 1501 is provided above the heat sink 3 in the Z direction, serving as an air passage for natural air cooling. This space 1501 is also connected to the rear space in the Y direction (such as the notch region 23 in Fig. 7).

[0070] A space 1502 is provided between the substrate 2 and the second case 12 (including the support portion 4B) on the right side in the X direction so as not to come into contact. Even when a load / force acts on the substrate 2 in the X direction by the heat sink 3, due to the presence of the space 1502, the heat generating component region 22 of the substrate 2 does not contact the second case 12. Thereby, deformation etc. of the substrate 2 (especially in the vicinity of the heat generating component region 22) are prevented or reduced.

[0071] Note that the support portions 4 (4A, 4B) may be formed integrally with the base plane of the cases (11, 12), or may be attached as separate components. The support portion 4 may be a portion extending out in the X direction from the main surface of the first case 11 (support portion 4A), or a portion extending out in the X direction from the main surface of the second case 12 (support portion 4B). The support portion 4 may be a portion extending upward in the Z direction from the bottom surface of the case (for example, the lower surface 1640 in Fig. 17), or a portion extending out in the Y direction from the front and rear side surfaces of the case (for example, the front surface 13 in Fig. 1).

[0072] [Structural examples of support portions] Fig. 17 shows a schematic explanatory diagram regarding a structural example of supporting the heat sink 3 by the support portion 4 of the case, which simplifies the cross-sectional view of Fig. 16. The entire circumference of the heat sink 3 is fixed so as to be sandwiched by the support portion 4A on the first case 11 side and the support portion 4B on the second case 12 side. In the vertical orientation of Fig. 17, the gravity in the Z direction acts in the longitudinal direction (the first direction) of the electronic device 1. The weight of the heat sink 3 is received by the case through the support portion 4. Thereby, the load on the substrate 2 by the heat sink 3 is reduced. Note that the dash-dot lines indicate the positions of the axes J1, J2 where the fixing screws 7 etc. are arranged. The heat generating component 5 is arranged in the region 1605 of the dashed frame.

[0073] The portions indicated by the dashed lines in the support part 4 (for example, portions 1601 and 1602) are examples of the locations where the heat sink 3 is sandwiched by the cases (11 and 12), and are examples of the locations where the surface of the support part 4 and the surface of the heat sink 3 are in contact with a predetermined clearance. In the example of FIG. 17, the support part 4B extending from the second case 12 side supports the convex portions 301 and 302 of the heat sink 3. In such portions indicated by the dashed lines (for example, portions 1601 and 1602), a predetermined clearance is provided between the support part 4 and the heat sink 3 in terms of design. The predetermined clearance is, for example, 0.5 mm.

[0074] With respect to the heat sink 3, the first case 11 and the second case 12 on the left and right are arranged such that the heat sink 3 is sandwiched by the support part 4 with a predetermined clearance from both sides. This support part 4 does not press and hold the heat sink 3, and the heat sink 3 is movable to a certain extent using the clearance.

[0075] Also, in the heat sink 3, the portions indicated by the dotted lines (for example, the lower surfaces 1631 and 1632) are examples of the locations that become the lower surfaces in the vertically placed state. The locations that become the lower surfaces in the heat sink 3 are not limited to the lower sides of the main surfaces, and exist at various positions as shown in the figure. For example, the convex portion 301 in the main surface also has the lower surfaces 1632 and 1633. The lower surfaces of the heat sink 3 in the vertically placed state, for example, the lower surface 1631 of the concave portion 313 and the lower surface 1632 of the convex portion 301, are supported by the support part 4, and in particular, the load due to gravity in the Z direction is supported. Thereby, the load and force exerted on the substrate 2 by the heat sink 3 can be reduced.

[0076] Not limited to the lower surface of the heat sink 3 and the support portion 4 as shown in Embodiment 1, the support portion 4 may be provided at other locations. Not limited to the vicinity of the four sides of the main surface of the heat sink 3, the support portion 4 may be provided at other locations. As an example of other locations, the support portion 4 may be provided on the lower surface 1633 on the left side of the convex portion 301. In that case, a protruding portion as shown by the dashed line may be provided as the support portion 4C in the space of the depression on the left side due to the convex portion 301. The support portion 4C may be a portion extending in the X direction from the main surface of the first case 11, or a portion extending from the side surface of the first case 11 or the like.

[0077] FIG. 18 shows a schematic cross-sectional view in the case where the electronic device 1 of FIGS. 16 and 17 is placed horizontally, similar to FIG. 17. In FIG. 18, an example of a location that becomes the lower surface of the heat sink 3, which is different from FIG. 17, is indicated by a dotted line. In the horizontal placement of FIG. 18, the gravity in the Z direction acts in the thickness direction of the electronic device 1. The locations that become the lower surface of the heat sink 3 in the horizontal placement, particularly the lower surfaces 1701 and 1702 of the convex portions 301 and 302, are supported by the support portion 4B (particularly the recess) on the side of the second case 12. Thereby, the load due to the gravity in the Z direction is supported, and the load / force acting on the substrate 2 by the heat sink 3 can be reduced.

[0078] The locations that become the lower surface of the heat sink 3 in the horizontal placement are not limited to the locations of the lower surfaces 1701 and 1702 shown in the figure, but exist at each position as shown in the figure. The support portion 4 may be provided at other locations. As an example of other locations, the support portion 4 may be provided on the lower surfaces of the recesses 311, 312, and 313. The support portion 4 may be provided for some of the heat radiation fins. For example, the support portion 4 may be added to the lower surface 1703 of the recess 311. In that case, for example, a protruding portion extending in the Y direction from the front surface 13 (FIG. 1) of the case may be provided as the support portion 4D in the space below the recess 311.

[0079] [Fixing Structure between Heat Sink and Substrate] FIG. 19 shows a schematic cross-sectional view in the X-Z plane in the case of vertical placement regarding the detailed fixing structure between the heat sink 3 and the substrate 2. The components include, from left to right, the heat sink 3, heat dissipation grease 9, heat-generating component 5, heat-generating component area 22 of the substrate 2, wave washer 6, fixing screw 7, etc. The holes 25 of the substrate 2 are aligned with the screw holes 33 at the positions of the axes J1 and J2 in the two convex portions 301 and 302 of the heat sink 3, and the fixing screw 7 is fastened with the wave washer 6 interposed therebetween. The hole 25 is an opening that is not a screw hole.

[0080] The fixing screw 7 is a stepped screw and has, as components, a screw head 71, a stepped portion (or an incomplete screw portion) 72, and a screw portion (or a complete screw portion) 73. The stepped portion 72 has a predetermined length greater than the thickness of the substrate 2 in the X direction and is inserted into the hole 25 of the substrate 2. The stepped portion 72 has a predetermined diameter smaller than the diameter of the hole 25, creating a gap between the substrate 2. The screw portion 73 has a smaller diameter than the stepped portion 72 and fits into the screw hole 33.

[0081] When fixing with the fixing screw 7, as shown in the figure, the stepped portion 72 passes through the hole 25 of the substrate 2, and one end of the stepped portion 72 abuts against the surface of, for example, the convex portion 301 of the heat sink 3. Also, the screw portion 73 fits into the screw hole 33 of the convex portion 301. Further, the wave washer 6, which is an elastic body, is sandwiched in the gap 1002 between the right-side surface near the hole 25 of the substrate 2 and the screw head 71, and the fixing screw 7 is fastened. Also, a gap 1001 is provided between the left-side surface near the hole 25 of the substrate 2 and the surface of the convex portion 301 of the heat sink 3 by the stepped portion 72, and the convex portion 301 of the heat sink 3 does not contact the surface of the substrate 2.

[0082] Since the fixing screw 7 is a stepped screw and has a structure in which the elastic wave washer 6 is interposed for fixing, in the state where the fixing screw 7 is fastened, the heat sink 3 is not directly fixed to the substrate 2 (or not completely fixed), and is movable with elasticity in the X direction (or semi-fixed). The elasticity of the wave washer 6, which is an elastic body, generates a force to move the fixing screw 7 to the right in the X direction with respect to the substrate 2, that is, a force to bring the heat sink 3 connected by the fixing screw 7 closer to the substrate 2.

[0083] After fixation, the heat sink 3 (especially the recess 312) is constantly pressed against the heat-generating component 5 with a pressing force equal to or greater than a predetermined pressing force due to the elasticity of the wave washer 6, and is in contact via the heat dissipation grease 9.

[0084] With such a fixed structure combined with the support structure by the aforementioned support portion 4, the load and force applied from the heat sink 3 to the substrate 2 are suppressed to within a predetermined range of load and force.

[0085] [Heat dissipation performance] As a comparative example with respect to Embodiment 1, when the structure is such that the heat-generating component region 22 and the notch region 23 (FIG. 7 etc.) that project in an island shape on the substrate 2 are not provided, the air flowing in from the vent hole of the second case 12 is blocked by the substrate 2, so it is difficult to flow into the space where the heat sink 3 etc. are located. Therefore, it is difficult to enhance the heat dissipation performance by the heat sink 3. On the other hand, in Embodiment 1, as described above (FIG. 7 etc.), since the notch region 23 etc. are provided, the air flowing in from the vent hole of the second case 12 easily flows into the space where the heat sink 3 etc. are located via the notch region 23 of the substrate 2. The air that has flowed near the heat sink 3 etc. flows out to the outside through the vent hole of the first case 11. Thereby, in Embodiment 1, the heat dissipation performance by the heat sink 3 can be enhanced compared to the comparative example.

[0086] [Effects, etc.] As described above, according to the electronic device 1 of Embodiment 1, the load and force on the substrate 2 by the heat sink 3 can be reduced, and deformation of the substrate 2 can be prevented and reduced. Since the electronic device 1 of Embodiment 1 is provided with a support structure for supporting the heat sink 3 by the support portion 4 of the case, the load and force on the substrate 2 due to the load of the heat sink 3 can be reduced. The electronic device 1 of Embodiment 1 has a structure in which the case (the first case 11 and the second case 12) and the heat sink 3 can be basically separated. As the support structure, the heat sink 3 is disposed within the region 400 of the support portion 4 of the case with a predetermined clearance, and the heat sink 3 is supported by the support portion 4 in the direction of gravity according to the installation form. Thereby, the load and force on the substrate 2 due to the load of the heat sink 3 can be reduced.

[0087] In addition, in the electronic device 1 of Embodiment 1, as a fixing structure of the heat sink 3 to the substrate 2, a structure is provided in which it is pressed and fixed by a fixing screw 7 (stepped screw) via a wave washer 6 (elastic body). Therefore, the load and force on the substrate 2 by the heat sink 3 can be reduced. Further, this fixing structure can be mounted with less space than the conventional fixing structure, and the space for air-cooling the heat sink 3 can be widely secured in the vicinity by the amount of space saved.

[0088] The electronic device 1 of Embodiment 1 has a structure in which the above fixing structure and support structure are combined, so that the heat sink 3 can be arranged and mounted in the case with less space, the load and force on the substrate 2 by the heat sink 3 can be suppressed, and the pressing force on the heat generating component 5 can be sufficiently ensured. Thereby, the heat dissipation performance by the heat sink 3 can be highly ensured. This structure is a structure in which a space is provided between the substrate 2 and the case, and the substrate 2 and the heat sink 3 are not directly fixed to the case, in other words, a structure fixed via the support portion 4. Thereby, while making the pressing force of the heat sink 3 on the heat generating component 5 a suitable pressing force equal to or greater than a predetermined pressing force, the load of the heat sink 3 on the substrate 2 is suppressed to be a load within a predetermined range. Thereby, cracks in the solder of, for example, the surface-mounted components on the substrate 2 can be prevented.

[0089] In the heat sink fixing structure of a conventional electronic device, as in the example of Patent Document 1, the heat sink is directly fixed to the substrate by screw fastening. In this fixing structure, since it is necessary to fix with a large pressing force according to the weight of the heat sink, the load / force on the substrate by the heat sink is large, and deformation of the substrate is likely to occur. On the other hand, since the electronic device 1 of Embodiment 1 is provided with a support structure together with the above fixing structure, the load / force on the substrate 2 by the heat sink 3 can be reduced, and deformation of the substrate 2 can be prevented.

[0090] [Modification Example (1)] In the above Embodiment 1, the heat sink 3 is arranged and housed in the region 400 (FIG. 5) by the support portion 4 with a predetermined clearance, but the present invention is not limited to this, and the heat sink 3 may be fixed by pressing in the region 400 by the support portion 4. For example, the four sides of the main surface of the heat sink 3 may be fixed so as to be pressed toward the inside of the heat sink 3 in the vertical and front-rear directions by the support portion 4, respectively. In the case of this modification example, the clearance distance is smaller than that in Embodiment 1, and the pressing between the support portion 4 and the heat sink 3 is a pressing force within a predetermined range. Also in this modification example, the load on the substrate 2 by the heat sink 3 can be reduced.

[0091] [Modification Example (2)] In the above-described Embodiment 1, the structure is designed to be compatible with both vertical and horizontal installation forms. As a modification, when the electronic device is a product that is used only in the vertical installation form or only in the horizontal installation form, dedicated heat sinks 3 and support parts 4 can be structured to correspond to the installation form. Specifically, it is as follows. In the case of an electronic device dedicated to vertical installation, the case is arranged vertically with the first direction being the vertical direction and the second direction being the horizontal direction, and the support part 4 supports the portion that becomes the lower surface of the heat sink 3 in the vertical position with a predetermined clearance (similar to FIG. 17 described above). In the case of an electronic device dedicated to horizontal installation, the case is arranged horizontally with the first direction being the horizontal direction and the second direction being the vertical direction, and the support part 4 supports the portion that becomes the lower surface of the heat sink 3 in the horizontal position with a predetermined clearance (similar to FIG. 18 described above).

[0092] As described above, the present invention has been specifically described based on the embodiments. However, the present invention is not limited to the above-described embodiments and can be variously modified without departing from the gist. Unless otherwise specified, each component may be singular or plural. Combinations of various configuration examples are also possible. In various configuration examples, except for the essential components, addition, deletion, replacement, etc. of components are possible.

Explanation of Reference Numerals

[0093] 1... Electronic device, 2... Substrate, 3... Heat sink, 4... Support part, 5... Heat-generating component, 6... Wave washer, 7... Fixing screw, 8... Positioning pin, 9... Heat-dissipating grease, 11... First case, 12... Second case.

Claims

1. A case having a first case and a second case, a substrate housed in the case, having a heat-generating component, and arranged such that a main surface extends in a first direction, a heat sink housed in the case, arranged to be in contact with the heat-generating component via heat-dissipating grease, and for dissipating heat from the heat-generating component, comprising: the heat sink is fixed to the substrate via a wave washer in a second direction perpendicular to the first direction so as to press the heat-generating component, a heat-generating component region having the heat-generating component on the substrate is arranged with a space provided in the second direction between it and the second case, the case has a support portion that projects toward the heat sink and supports the heat sink so as to reduce a load acting on the substrate due to the load of the heat sink, the substrate is fixed to the heat sink by screwing a stepped screw via the wave washer in the second direction, an electronic device.

2. In the electronic device according to Claim 1, the case can be arranged in either a vertical installation form with the first direction as the vertical direction and the second direction as the horizontal direction, or a horizontal installation form with the first direction as the horizontal direction and the second direction as the vertical direction, the support portion supports each of the four sides of the main surface of the heat sink at at least one location for each side with a predetermined clearance therebetween, an electronic device.

3. In the electronic device according to Claim 1, the case is arranged in a vertical installation form with the first direction as the vertical direction and the second direction as the horizontal direction, the support portion supports a location that becomes the lower surface of the heat sink in the vertical arrangement with a predetermined clearance therebetween, an electronic device.

4. In the electronic device according to Claim 1, the case is arranged in a horizontal installation form with the first direction as the horizontal direction and the second direction as the vertical direction, the support portion supports a location that becomes the lower surface of the heat sink in the horizontal arrangement with a predetermined clearance therebetween, an electronic device.

5. In the electronic device according to Claim 1, when the main surface of the substrate is viewed in plan in the second direction, the heat-generating component region has a shape in which it protrudes outward from a main substrate region having no heat-generating component via an opening region and a connection region, and a notch region where the heat sink is exposed is provided adjacent to the heat-generating component region, an electronic device.

6. In the electronic device according to Claim 1, The heat sink has irregularities at least in the first direction. The support portion includes a first support portion provided on the inner surface of the first case for supporting a predetermined portion of the heat sink, and a second support portion provided on the inner surface of the second case for supporting a predetermined portion of the heat sink. The convex portion of the heat sink is fixed by screwing the stepped screw. Electronic device.

7. An assembling method for assembling an electronic device, wherein the electronic device includes a case having a first case and a second case, a substrate housed in the case, having heat-generating components, and arranged such that a main surface extends in a first direction, a heat sink housed in the case, arranged to be in contact with the heat-generating components via heat dissipation grease for dissipating heat from the heat-generating components, and is provided with the heat sink is fixed to the substrate via a wave washer in a second direction perpendicular to the first direction so as to press the heat-generating components with a pressing force within a predetermined range, a heat-generating component region having the heat-generating components on the substrate is arranged with a space provided in the second direction between the second case, the case has a support portion that projects toward the heat sink to support the heat sink so as to reduce a load acting on the substrate due to the load of the heat sink, the assembling method includes a step of arranging the heat sink in a region surrounded by the support portion of the first case, a step of fixing the substrate to the first case and the heat sink by screwing a stepped screw via the wave washer in the second direction, a step of fixing the second case to the first case, and is an assembling method.

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