JP2022123971A - Heat sink case, printed circuit board and substrate structure - Google Patents

Abstract

To provide a heat sink case that can suppress electromagnetic radiation from a heat sink with a simple configuration when a heat sink is mounted on a printed wiring board.SOLUTION: A heat sink case covering electronic components mounted on a printed circuit board has a top plate part of a conductive body covering the electronic components, and a plurality of finger parts of a conductive body contacting a peripheral edge of the top plate part and projecting in a direction intersecting the top plate part and surrounding the electronic components. Each of the finger components has a spring portion provided at one end with a conductive portion contacting the top plate part and extending in a direction intersecting the conductive portion, and a clamping portion provided at the other end of the spring portion and clamping each of the plurality of jumper components of the conductive body fixed to the printed circuit board to surround the electronic component.SELECTED DRAWING: Figure 4

Description

The present invention relates to a heat sink case, a printed circuit board, and a substrate structure for suppressing electromagnetic wave radiation from a radiator when the radiator is mounted on the printed wiring board.

2. Description of the Related Art Heat-generating components such as integrated circuits (ICs) mounted on printed wiring boards sometimes use radiators (heat sinks) to facilitate their cooling. On the other hand, the use of a heat sink sometimes causes a problem that unwanted electromagnetic waves (EMI) from the printed wiring board are amplified by passing through the heat sink. One of the countermeasures is to connect the heat sink to the ground plane of the printed wiring board. Japanese Unexamined Patent Application Publication No. 2002-200002 describes an integrated circuit mounting structure with EMI countermeasures.

JP 2010-245342 A

In the conventional technology described above, when the heat sink is to be electrically connected to the ground plane of the printed wiring board, the printed wiring board must be provided in advance with conductor lands, through holes, or the like for electrically connecting the heat sink and the ground plane. In this case, depending on the shape of the heat sink and the positions of the conductor lands and through-holes, resonance may occur in the heat sink, and EMI may increase at a specific frequency. As countermeasures, to prevent resonance from occurring in the heat sink, prepare a large number of conductor lands and through holes on the printed wiring board, change the positions of the conductor lands and through holes, and change the shape of the heat sink. However, in any case, costs are unavoidable. In addition, it may be difficult to change the shape or design due to layout restrictions. There was a problem.

The present invention has been devised in view of the problems of the prior art described above. It is an object to provide a substrate structure.

A heat sink case according to the present invention is a heat sink case that covers an electronic component mounted on a printed circuit board, comprising: a conductive top plate component that covers the electronic component; a plurality of conductor finger parts surrounding the part and protruding in a direction intersecting with the top plate part, each of the plurality of finger parts having a conductive portion at one end thereof contacting the top plate part; a spring portion extending in a direction crossing the conducting portion; and a plurality of conductive jumper parts each provided at the other end of the spring portion and fixed to the printed circuit board so as to surround the electronic component. and a sandwiching portion for sandwiching.

The printed circuit board of the present invention is the printed circuit board for fixing the heat sink case, and has a ground plane and a plurality of ground lands connected to the ground plane, each of the ground lands being connected to the electronic device. The jumper component is fixed so as to surround the component, and has leg portions at least at both ends thereof and bench portions connecting the leg portions at both ends, and the leg portions of the jumper component are joined to the ground lands, respectively. fixed, the bench portion of the jumper component extending away from the mounting surface along the mounting surface of the printed circuit board, the bench portion being sandwiched between the clamping portions of the finger component; .

The substrate structure of the present invention includes: a substrate having a mounting area for mounting an electronic component on one surface and a ground land in an area outside the mounting area; and one surface on the area outside the mounting area. and a support portion that is joined to the ground land at both ends of the bench portion and supports the bench portion with respect to the substrate. a plurality of support parts for conductors, a top plate part extending so as to cover the mounting area on the first surface, and a conductive part in contact with the top plate part at one end, and at the other end and a conductive spring component having a holding portion that sandwiches the bench portion.

ADVANTAGE OF THE INVENTION According to this invention, when mounting a heat sink on a printed wiring board, the effect which can suppress electromagnetic wave radiation from a heat sink with a simple structure is acquired.

1 is a schematic perspective view showing the appearance of a board assembly in which a heat sink case, which is a first embodiment according to the present invention, is mounted on a printed wiring board; FIG. FIG. 2 is a top view showing jumper components, finger components, and the like arranged on a printed wiring board in which the heat sink main body of the first embodiment is seen through; 1 is a schematic exploded perspective view showing a board assembly in which a heat sink case of the first embodiment is mounted on a printed wiring board; FIG. 2 is a schematic cross-sectional view showing a cross-section of the substrate assembly along line xx of FIG. 1; FIG. 4 is a schematic perspective view showing one jumper component mounted on the printed wiring board in the first embodiment; FIG. 1 is a schematic perspective view showing an electronic component mounted on a printed wiring board and four jumper components therearound in the first embodiment; FIG. FIG. 4 is a schematic perspective view showing one finger component mounted on the printed wiring board in the first embodiment; FIG. 4 is a schematic perspective view showing how four jumper parts are attached around the electronic parts mounted on the printed wiring board in the first embodiment; 2 is a graph showing changes in the frequency and intensity of electromagnetic waves radiated when a heat sink body arranged on a printed wiring board is not connected to a ground plane on the printed wiring board, which serves as a reference. 5 is a graph showing changes in the frequency and intensity of electromagnetic waves radiated when only conductor pads and through-holes provided on a printed wiring board are connected to a heat sink body as in the prior art as a comparative example. 5 is a graph showing changes in the frequency and intensity of electromagnetic waves radiated from the heat sink case of the embodiment. FIG. 11 is a schematic perspective view showing a plurality of narrow finger components mounted on a printed wiring board in the second embodiment; FIG. 11 is a schematic perspective view showing an annular jumper component used in modifications of the first and second embodiments;

Electronic devices according to embodiments of the present invention will be described below with reference to the drawings. In addition, the present invention is not limited to the following examples. In addition, in the embodiments, components having substantially the same functions and configurations are denoted by the same reference numerals, thereby omitting redundant description.

(Description of configuration)
FIG. 1 is a schematic perspective view showing the external appearance of a substrate assembly in which a heat sink case 11 according to the first embodiment covers an electronic component 15 mounted on a printed wiring board 13 (hereinafter also referred to as a substrate) (inside the heat sink case 11). is indicated by a dashed line). FIG. 2 is a top view showing the jumper component 17, the finger component 19 and the like arranged on the substrate 13 with the heat sink main body (broken line) seen through. FIG. 3 is a schematic exploded perspective view showing such a substrate assembly. 4 is a schematic cross-sectional view showing a cross-section of the substrate assembly along line xx of FIG. 1. FIG. Various electronic components are mounted on the upper mounting surface of the substrate 13 in the figure to form an electronic circuit. Only the component 15 is shown, and other electronic components are omitted.

(heat sink case)
The heat sink case 11 is in contact with a conductive heat sink main body 11a (top plate component) which is a main body covering the electronic component 15, and a peripheral portion of the lower surface of the heat sink main body, surrounds the electronic component 15, and extends in a direction intersecting the heat sink main body 11a. and four finger parts 19 of protruding conductors. The heatsink case 11 provides electrical continuity between the heatsink body 11a and the ground plane GP of the substrate 13 using metallic or conductive jumper parts 17 and finger parts 19 .

(Heat sink body)
As shown in FIGS. 1 to 4, a heat sink main body 11a, which is a radiator plate made of metal or the like, is provided so as to sandwich an electronic component 15 on a substrate 13 so as to face it. A thermally conductive sheet TIM having flexibility is provided so as to face 15 . The thermally conductive sheet TIM sandwiched between the heat sink main body 11a and the electronic component 15 fills small gaps and irregularities between the upper surface of the heat sink main body and the upper surface of the heat sink main body, and serves as a thermal interface material that efficiently conducts heat. Interface Material) It is a thin film member, but it is not limited to a sheet form, and may be arranged in a viscous form.

The heat sink main body 11 a has a plurality of heat radiation fins 11 b protruding from the upper surface on the opposite side of the substrate 13 .

Also, the heat sink body 11 a is connected to the ground plane GP mounted on the substrate 13 via four pairs of jumper parts 17 and finger parts 19 surrounding the electronic parts 15 . By surrounding or shielding electronic component 15 with heat sink body 11a and jumper component 17 and finger component 19, EMI from electronic component 15 and its surroundings can be reduced.

(Jumper part)
FIG. 5 is a schematic perspective view showing one jumper component 17 out of four.

Each jumper component 17 has a shelf shape, and has leg portions FT at both ends and shelf plate portions BSF connecting the leg portions FT at both ends. The shelf portion BSF of the jumper component 17 extends away from the mounting surface along the mounting surface of the substrate 13, and the finger component 19 sandwiching the leg portion FT is fixed to the shelf portion BSF. The legs FT at both ends of the jumper part 17 are respectively joined and fixed to the ground lands GL. A plurality of ground lands GL are each connected to a ground plane GP. The ground land GL and ground plane GP are provided in advance on the mounting surface of the substrate 13 . Therefore, each ground land GL is also fixed so as to surround the electronic component 15 .

Thus, the four jumper parts 17 shown in FIG. 6 are fixed in advance on the mounting surface of the substrate 13 so as to surround the electronic parts 15 by being connected to the ground plane GP.

(finger parts)
FIG. 7 is a schematic partial perspective view showing a portion of one of the four finger pieces 19. FIG.

Each of the finger parts 19 has a conductive portion CNT at one end that contacts the heat sink main body 11a (see FIG. 4) and a spring portion 19a that extends in a direction crossing the conductive portion, and the other end of the spring portion 19a. and clamping portions CLP that sandwich each of the shelf plate portions BSF (see FIG. 5) of the jumper component 17 . A general jumper is a conductor structure that connects distant electric circuits, but the jumper part of this embodiment is a member that is connected to the ground plane GP and serves as the base of the finger parts.

As shown in FIG. 7, the conducting portion CNT and the spring portion 19a of the finger component 19 are provided with a plurality of slits SLT extending from the conducting portion CNT to the clamping portion CLP to divide the conducting portion CNT. The slit SLT can suppress the rigidity of the spring portion 19a and ensure its flexibility.

The spring portion 19a of the finger component 19 is inclined with respect to the heat sink main body 11a at an angle that is not perpendicular to the substrate 13 between the conducting portion CNT and the clamping portion CLP. The inclination of the spring portion 19a can ensure the elasticity of the spring portion 19a. That is, the spring portion 19a is a leaf spring having a Z-shaped cross section.

(Description of operation)
First, a ground land GL for mounting the jumper component 17 (see FIG. 5) is provided on the board 13 . In the case of the jumper component 17 shaped as shown in FIG. 5, two ground lands GL are required for each jumper component 17 . In order to suppress resonance in the heatsink body 11a as much as possible, it is desirable that the heatsink body 11a and the ground plane GP of the substrate 13 are uniformly conductive over the entire surface of the heatsink body 11a. are evenly arranged on the substrate 13 excluding electronic components (not shown) to be mounted.

Next, a procedure after manufacturing the substrate 13 will be described. It is assumed that the substrate 13 is manufactured as a general laminated substrate, but a multi-layered substrate, a build-up substrate, or the like may also be used. After the substrate 13 is manufactured, components (not shown) such as electronic components such as ICs are mounted and soldered to the substrate 13 . At that time, the jumper component 17 is also mounted (see FIG. 6). In many cases, an automatic mounting machine can be used for the jumper component 17 having the shape shown in FIG. 5, and soldering can be performed in the existing mounting process.

Next, the heat sink main body 11a is attached to the substrate 13 on which each component is mounted.

As shown in FIG. 8, the purpose of the heat sink main body 11a is to efficiently cool the high-heat-generating components among the components mounted on the substrate 13. A thermally conductive sheet TIM (or grease or the like) of thermal interface materials is placed on the electronic component 15 for contact.

Finger parts 19 are attached to jumper parts 17 as shown in FIG. The finger part 19 is a conductor, and is composed of a clamping part CLP (fixed part) fixed to the jumper part 17 and a conductive part CNT in contact with the heat sink main body 11a to ensure conduction. The clamping part CLP at the bottom of the jumper part 17 has a clip shape, and by clamping it to the jumper part 17, the finger part 19 is fixed to the jumper part 17 while securing the conduction between the jumper part 17 and the finger part 19. becomes possible (see FIG. 7). The conducting part CNT on the upper part of the jumper part 17 is one end of the spring part 19a of the plate spring. By pressing the heat sink main body 11a against the finger part 19, the conducting part CNT is deformed so as to come into wide contact with the lower surface of the heat sink main body 11a. , it is possible to ensure electrical connection between the heat sink main body 11a and the finger parts 19 (see FIG. 7).

Then, the heat sink main body 11a shown in FIG. 3 is placed on the heat conductive sheet TIM on the electronic component 15 and the finger component 19 on the jumper component 17, and through holes (not shown) provided on the diagonal lines of the heat sink main body 11a ) and screw holes SCH provided in the substrate 13, two male screws SC are passed through and screwed into female screws (not shown) on the back of the substrate 13 to attach the heat sink body 11a to the substrate. 13 (see FIG. 1).

(Description of operation)
Electromagnetic waves are radiated from wiring and components (not shown) connected to the electronic component 15 due to the operation of the circuit on the substrate 13 . A part of the radiated electromagnetic wave enters the heat sink main body 11a. Depending on the size and shape of the heat sink main body 11a, the incident electromagnetic wave may resonate and be strongly radiated into space. It is possible to The heatsink case of the present embodiment makes it possible to secure many connections between the heatsink body 11a and the ground plane GP, thereby suppressing radiation of electromagnetic waves from the heatsink body 11a.

(Explanation of effect)
As described above, according to the first embodiment, by using the jumper component 17 and the finger component 19, it is possible to obtain the effect of reducing EMI.

As a comparison of the EMI reduction effect, the radiation of electromagnetic waves from the heat sink main body 11a was measured.

FIG. 9 is a graph showing EMI (frequency/electromagnetic wave intensity) when the heat sink main body 11a arranged on the substrate 13 is not connected to the ground plane GP on the substrate 13. As shown in FIG. X in the graph indicates the peak of the electromagnetic wave intensity at each frequency. Each such peak is used as a reference for comparison.

FIG. 10 is a graph showing EMI (frequency/electromagnetic wave intensity) when only the conductor pads and through holes provided on the substrate 13 are connected to the heat sink main body 11a as in the prior art as a comparative example. In the graph, ◯ indicates the peak of the electromagnetic wave intensity at each frequency. In the comparative example, while the peak is reduced compared to the reference, there is also a frequency where the peak is hardly reduced. This is because there are few connections between the heat sink main body 11a and the ground plane GP, and especially in a high frequency range with a short wavelength, connection with the ground plane GP could not be provided at a resonance point.

FIG. 11 is a graph showing EMI (frequency/electromagnetic wave intensity) in the case of the heat sink case of this embodiment. In the graph, ▽ indicates the peak of the electromagnetic wave intensity at each frequency. As is clear from FIG. 11, it can be confirmed that in this embodiment, EMI is reduced with respect to the reference (FIG. 9) regardless of the frequency. This EMI reduction effect is presumed to be due to the fact that the connection with the ground plane GP could be effectively provided at the resonance part of the heat sink main body 11a compared to the prior art, which is a comparative example.

(Description of configuration)
In this embodiment, instead of the four wide finger parts 19 of the first embodiment, as shown in FIG. It is the same as the first embodiment except that it consists of a single row of narrow finger members 191 . In the first embodiment, it was assumed that the finger part 19 used for each jumper part 17 had a width corresponding to the length of the jumper part 17. A part 191 is selected and a plurality of finger parts 191 are attached to each one jumper part 17 .

(Description of operation)
The operation in the second embodiment is the same as that in the first embodiment.

As described above, according to the present embodiment, the same effects as those of the first embodiment can be obtained, and it is possible to select a less expensive finger component 191, and the finger component 191 can be positioned freely. spreads.

(Explanation of effect)
Also in the second embodiment, the same effect as in the first embodiment can be expected. However, since the contact between the small finger parts 191 and the heat sink main body 11a is less than in the first embodiment, the effect of suppressing electromagnetic waves is limited unless the finger parts 191 are appropriately arranged at the resonance part of the heat sink main body 11a. There is a risk that In that case, since the positions of the plurality of finger components 191 can be freely adjusted on the jumper component 17, the plurality of finger components 191 can be arranged on the jumper component 17 at positions where electromagnetic waves are most suppressed. This embodiment is superior to the first embodiment from the viewpoint of adjustment.

(Modification)
In this example, instead of the four wide jumper parts 17 of the first embodiment, as shown in FIG. is the same as the embodiment of

In the first and second embodiments, two ground lands GL were required for each finger part 19 used. , four ground lands GL. As a result, the number of ground lands GL required for the substrate 13 can be suppressed, and the ratio of the ground lands GL in the substrate 13 can be reduced as compared with the first and second embodiments. In this case, either of the finger parts 19, 191 described in the first and second embodiments may be used.

11 Heat sink case 11a Heat sink body 11b Radiation fin 13 Substrate, printed circuit board 15 Electronic component 17, 171 Jumper component 19, 191 Finger component 19a Spring portion BSF Shelf plate portion CNT Conductive portion CLP Clamping portion FT Leg portion GL Ground land GP Ground plane TIM thermal conductive sheet

Claims (9)

A heat sink case covering an electronic component mounted on a printed circuit board,
a conductive top plate component covering the electronic component;
a plurality of conductor finger parts that are in contact with the periphery of the top plate component, surround the electronic component, and protrude in a direction crossing the top plate component;
has
Each of the plurality of finger parts includes a spring part provided at one end with a conducting part that contacts the top plate part and extending in a direction intersecting the conducting part, and a spring part provided at the other end of the spring part and serving as the electronic and a sandwiching portion sandwiching each of a plurality of conductive jumper components fixed to the printed circuit board so as to surround the components. 2. The heat sink case according to claim 1, wherein the spring portion is inclined with respect to the top plate component at an angle that is not perpendicular to the printed circuit board between the conduction portion and the clamping portion. 3. The heat sink case according to claim 1, further comprising a thermally conductive material sandwiched between said electronic component and said top plate component. 4. The heat sink case according to any one of claims 1 to 3, wherein the top plate component has heat radiation fins formed so as to protrude from the back surface on the opposite side of the printed circuit board. 2. The conducting portion and the spring portion of each of the plurality of finger parts are provided with at least one slit extending from the conducting portion to the clamping portion and dividing the conducting portion. 5. The heat sink case according to any one of 1 to 4. 5. The heat sink case according to any one of claims 1 to 4, wherein each of said plurality of finger parts is composed of a row of a plurality of narrow finger parts. The printed circuit board for fixing the heat sink case according to claim 1,
a ground plane and a plurality of ground lands each connected to the ground plane;
each of the ground lands is secured to surround the electronic component;
The jumper component has at least leg portions at both ends thereof and bench portions connecting the leg portions at both ends,
the legs of the jumper component are joined and fixed to each of the ground lands;
the bench portion of the jumper component extends along and away from the mounting surface of the printed circuit board;
A printed circuit board according to claim 1, wherein said bench portion is sandwiched between said clamping portions of said finger components. 8. The printed circuit board of claim 7, wherein the plurality of jumper components are interconnected to form a ring. a substrate having a mounting area for mounting an electronic component on one surface and having a ground land in an area outside the mounting area;
a bench portion extending along the surface 1 on a region outside the mounting region so as to surround the mounting region while being spaced apart from the surface 1; a plurality of conductor support components having supports for supporting the bench with respect to the substrate;
a top plate part extending to cover the mounting area on the first surface;
a conductive spring component having a conductive part at one end that contacts the top plate component and a clamping part that sandwiches the bench part at the other end;
A substrate structure comprising:

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