Base plate

Abstract

To provide a lightweight base plate of a circuit board used as the ground of a board.SOLUTION: A base plate 100 is used as a ground by being superimposed on a substrate 20, and includes a metal plate 10 having an opening provided on the substrate opposite an electronic component (MOSFET) 21 protruding from the substrate toward the base plate 100, the opening being arranged to follow the outline of the electronic component when viewed in plan, one or more frame bodies 13 having an opening of the same shape as the opening opposite the opening and having a predetermined thickness, and a bottom 14 covering the opening provided in the frame body 13, with the metal plate 10, the one or more frame bodies 13, and the bottom 14 being superimposed in this order.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] The present invention relates to a base plate for a circuit board. [Background technology]

[0002] In recent years, since placing wireless communication base stations at high altitudes widens the communication area per base station, communication systems using HAPS (High Altitude Platform Station), known as a high-altitude platform that mounts wireless stations on aircraft that fly at high altitudes, have been developed.Aircraft used in HAPS are desirably as lightweight as possible in order to stay in the air, and it is preferable that this weight reduction be achieved in, for example, circuit boards and heat sinks.

[0003] Patent Document 1 discloses a technique for achieving miniaturization by providing a base plate inside a heat sink. [Prior art documents] [Patent documents]

[0004] [Patent Document 1] International Publication No. 2014 / 132425 Summary of the Invention [Problem to be solved by the invention]

[0005] Incidentally, recesses must be formed in locations facing electronic circuit components mounted on circuit boards. One possible method for achieving this is to machine a metal block used as a base plate. However, the weight and processing costs of machined base plates have long been a concern. Another method that can be considered is to form recesses by pressing thin metal sheets. However, this method has the problem of creating gaps between the recesses and the electronic circuit components due to the nature of press processing.

[0006] SUMMARY OF THE INVENTION The present invention has been made in view of the above problems, and has an object to provide a base plate that is lighter than conventional ones and has no gap between the recess and the electronic circuit component. [Means for solving the problem]

[0007] In order to solve the above problems, the base plate of the present invention is a base plate that is superimposed on a substrate and used as a ground, and comprises a metal plate that is provided on the substrate and has an opening that is positioned opposite an electronic component that protrudes from the substrate toward the base plate and that follows the outline of the electronic component when viewed in a plane, one or more frame bodies that have an opening of the same shape as the opening opposite the opening and have a predetermined thickness, and a base portion that covers the opening provided in the frame body, and is formed by superimposing the metal plate, the one or more frame bodies, and the base portion in that order.

[0008] In addition, the base plate may have one or more frame bodies superimposed thereon such that the length by which the electronic components protrude from the substrate is less than or equal to a length based on the thickness of the metal plate and a predetermined thickness of the frame body.

[0009] The base plate may be made of aluminum.

[0010] In addition, in the base plate, the board may be a communication board.

[0011] In addition, in the above-mentioned base plate, the communication board and the base plate may be mounted on an unmanned aircraft of a HAPS (High Altitude Platform Station). [Effects of the Invention]

[0012] The base plate according to the present invention can be provided with no components around the frame and bottom, making it possible to provide a base plate that is lighter than a base plate formed by machining. Furthermore, the base plate according to the present invention can provide a base plate that can suppress the intrusion of ground current more effectively than a base plate formed by pressing, because no gap is formed between the frame and the substrate. [Brief explanation of the drawings]

[0013] [Figure 1] 1A is a perspective view showing the appearance of a base plate as seen from above, and FIG. 1B is a perspective view showing the appearance of a base plate as seen from below. [Figure 2] FIG. [Figure 3] 1A is a top view of a base plate, FIG. 1B is a front view of a base plate, FIG. 1C is a side view of a base plate, and FIG. 1D is a bottom view of a base plate. [Figure 4] 1A is a perspective view showing a state in which the communication board and the base plate are joined together, and FIG. 1B is a cross-sectional view taken along line AA of the state in which the communication board and the base plate are joined together. [Figure 5] 1A is a cross-sectional view showing a state in which a heat sink is joined to a base plate, and FIG. [Figure 6] 1A is a cross-sectional view showing a state in which the communication board and the base plate are joined together, (b) is a cross-sectional view showing a state in which the communication board and the machined base plate are joined together, and (c) is a cross-sectional view showing a state in which the communication board and the press-formed base plate are joined together. DETAILED DESCRIPTION OF THE INVENTION

[0014] Hereinafter, a base plate according to the present invention will be described with reference to the drawings.

[0015] <Configuration> <Configuration of base plate 100> Fig. 1(a) is a perspective view of the base plate 100 seen from above, and Fig. 1(b) is a perspective view of the base plate 100 seen from below. Fig. 2 is an exploded perspective view of the base plate 100 shown in Fig. 1(a). Fig. 3(a) is a top view of the base plate 100, Fig. 3(b) is a front view of the base plate 100, Fig. 3(c) is a side view of the base plate 100, and Fig. 3(d) is a bottom view of the base plate 100.

[0016] The base plate 100 may be used as a ground (ground layer) for a circuit board. As shown in Fig. 2, the base plate 100 is formed by laminating a metal plate 10, one or more frame bodies 13, and a bottom 14 in this order.

[0017] The metal plate 10 has openings 16 at positions facing electronic components that are to be mounted on the circuit board and that protrude toward the base plate 100 when the metal plate 10 is superimposed on the circuit board.

[0018] Opening 16 conforms to the outline of the electronic component provided on the opposing circuit board (printed circuit board, semiconductor board, dielectric board) in plan view, i.e., has the same shape as the outline of the electronic component. Opening 16 also has approximately the same size as the outline of the electronic component in plan view (opening 16 may be larger than the electronic component as long as the electronic component can be inserted into opening 16). In other words, the size of the electronic component is equal to or smaller than the size of opening 16. However, it is preferable to minimize the gap between opening 16 and the inserted electronic component.

[0019] The frame body 13 is a plate material in which an opening 17 of the same shape and size is provided at a position opposite to the opening 16 of the metal sheet 10. The overall size (area) of the frame body 13 is preferably smaller (narrower) than the metal sheet 10, and the weight of the entire base plate 100 can be reduced accordingly. The number of frame bodies 13 to be used is determined according to the height of the electronic component to be inserted. In other words, the number of frame bodies 13 to be stacked is determined so that the length of the electronic component protruding toward the base plate 100 is equal to or less than the thickness of the metal sheet 10 + the thickness of each frame body 13 x the number of frame bodies 13.

[0020] The bottom 14 is a plate material that covers the opening 17 of the opposing frame body 13. The size (area) of the bottom 14 may be smaller (narrower) than the metal plate 10 and may be the same as the size of the entire frame body 13.

[0021] A recess 11 is formed by the opening of the metal plate 10, the opening of the frame 13, and the bottom 14. Into the recess 11, an electronic component of an opposing circuit board is inserted.

[0022] The metal plate 10, one or more frame bodies 13, and bottom 14 are provided respectively, and are locked by locking members 12 through openings 15 facing each other so that no gaps are formed between them in the stacking direction.

[0023] As an example, the locking member 12 may be realized by a bolt and a nut. Note that instead of the locking member 12, an adhesive or the like may be used to bond the metal plate 10 and the frame 13, and the frame 13 and the bottom 14 to each other.

[0024] The base plate 100, i.e., the metal sheet 10, the frame 13, and the bottom 14, may be made of a metal that is lightweight and can be used as a ground, and is basically made of aluminum. However, the base plate may be made of a material other than aluminum. For example, copper, which has high thermal conductivity, or titanium, which is lightweight, may be used. Aluminum has a lower specific gravity than copper and can be made at low cost. Aluminum also has higher thermal conductivity than titanium and can be made at low cost. The metal sheet 10, the frame 13, and the bottom 14 may each be formed by cutting out a single thin aluminum sheet to form the shape shown in the figure. In addition to serving as a ground, the base plate 100 may also function as a heat sink.

[0025] The above is an example of the configuration of the base plate 100.

[0026] <Usage of the base plate 100> 4A and 4B are diagrams showing one form of use of the base plate 100, in which FIG. 4A is a perspective view showing a state in which a circuit board is superimposed on the base plate, and FIG. 4B is a cross-sectional view taken along line AA shown in FIG. 4B.

[0027] As shown in Fig. 4(a), a circuit board 20 is superimposed on the base plate 100. An electronic component 21 is provided on the circuit board 20. The electronic component 21 protrudes from the circuit board 20 toward the base plate 100 by the height of the electronic component 21, and this protruding portion fits into a recess 11 formed in the base plate 100 as shown in Fig. 4(b).

[0028] As an example, the circuit board may be a communication circuit board, and the electronic component 21 may be a communication circuit, but these are not limited thereto. Components formed in this manner can be used, for example, in unmanned aircraft used in HAPS (High Altitude Platform Station). Unmanned aircraft used in HAPS remain in the air at extremely high altitudes (stratosphere) for long periods of time and function as airborne wireless base stations, so lightweight is essential. Therefore, the base plate 100 according to this embodiment can be realized to be lighter than conventional ones, thereby contributing to weight reduction of unmanned aircraft.

[0029] 5A and 5B are diagrams showing another use of the base plate 100. Fig. 5A shows a cross-sectional view of the base plate 100 to which a heat sink 50 is joined, and Fig. 5B is a perspective view of the heat sink 50.

[0030] 5(a) shows an example in which a heat sink 50 is provided on the underside of the base plate 100. By providing the heat sink 50 on the underside of the base plate 100, heat generated in the electronic component 21 can be dissipated, thereby reducing the possibility of thermal runaway occurring in the electronic component 21.

[0031] FIG. 5(b) is a perspective view showing an example of the heat sink 50. For the purpose of weight reduction, the heat sink 50 may be made of aluminum, similar to the base plate 100. As shown in FIG. 5(b), the heat sink 50 may be formed by, for example, cutting out three sides of an aluminum sheet metal and pressing down the cutouts to form a plurality of heat dissipation fins 51. This allows the lightweight heat sink 50 to dissipate heat from the electronic component 21. Note that FIG. 5(b) shows an example in which the positions of the heat dissipation fins 51 on the heat sink 50 are varied depending on the row. This is because heat dissipation efficiency may be improved by varying the positions of the heat dissipation fins 51 rather than by aligning them.

[0032] <Comparison between Base Plate 100 and conventional base plates> The base plate 100 according to this embodiment will be compared with a conventional base plate using FIG.

[0033] Fig. 6(a) is a cross-sectional view of the base plate 100 according to this embodiment, Fig. 6(b) is a cross-sectional view of a conventional base plate produced by machining, and Fig. 6(c) is a cross-sectional view of a conventional base plate produced by pressing. All of Figs. 6(a) to (c) show examples in which a circuit board 20 is mounted.

[0034] 6(b), when the base plate 60 is produced by cutting, a block material having a thickness corresponding to the required depth of the recess is prepared, and the recess is formed by cutting out the block material. As a result, compared to the base plate 100 according to this embodiment shown in FIG. 6(a), there is a problem in that the base plate 60 is heavier by the amount of the material shown in the region 61.

[0035] Furthermore, when the base plate 62 is produced by press working as shown in FIG. 6(c), the recessed portion is formed by pressing, which inevitably results in an inclined wall surface of the recessed portion, as shown in the figure. As a result, compared to the base plate 100 according to this embodiment shown in FIG. 6(a), a gap 63 is generated between the electronic component 21 and the base plate 62 as shown in FIG. 6(c). In this case, the presence of the gap 63 causes sneaking of ground current. Here, if the electronic component 21 is a communication circuit, this sneaking of ground current can cause a problem of degrading the quality of the wireless signal, particularly a degradation in the signal modulation accuracy (EVM: Error Vector Magnitude).

[0036] The base plate 100 according to this embodiment shown in FIG. 6(a) can solve these problems.

[0037] <Summary> The base plate 100 according to this embodiment can reduce its weight and processing costs compared to a base plate manufactured by machining. Specifically, the weight of the base plate 100 can be reduced by the area 61 shown in FIG. 6(b), and the metal plate 10, frame 13, and bottom 14 can all be manufactured by simply cutting out a single piece of thin aluminum plate, reducing processing costs. Furthermore, the base plate 100 does not form the gap 63 shown in FIG. 6(c), as compared to a base plate manufactured by press processing. This prevents ground current from leaking, which prevents degradation of communication quality.

[0038] <Modification> The base plate according to the above embodiment is not limited to the above embodiment, and may be realized by other methods. Various modifications will be described below.

[0039] (1) In the above embodiment, an example in which one recess is provided in the base plate 100 has been described, but the number of recesses is not limited to one. The number of recesses may be equal to the number of electronic components provided on the opposing circuit board and protruding toward the base plate 100. The shape of the opening may be created according to the shape and size of each electronic component, and the number of frame bodies 13 to be provided may be determined according to the degree of protrusion of the electronic components. In this way, the number of stacked frame bodies 13 can be determined appropriately according to the degree of protrusion of the electronic components.

[0040] (2) In the above embodiment, an example of a rectangular prism-shaped opening was described. However, as mentioned above, this shape must correspond to the shape of the electronic component. For example, if the electronic component is circular in plan view, the opening will also be circular.

[0041] (3) The above-described embodiments and modifications may be combined as appropriate.

[0042] (4) According to each aspect of the present disclosure described above, it is possible to provide a lightweight base plate that does not allow ground current to flow around. This in turn makes it possible to reduce the weight of unmanned aerial vehicles in HAPS and improve communication performance, thereby contributing to the achievement of Goal 9 of the Sustainable Development Goals (SDGs), “Build resilient infrastructure, promote inclusive and sustainable industrialization, and promote inclusive and sustainable industrialization.” [Explanation of symbols]

[0043] 100 base plate 10 Sheet Metal 11 Recess 12 Locking member 13 Frame 14 Bottom 15 Aperture 16 Opening 17 Opening 20 Substrate 21 Electronic Components (MOSFET) 50 Heatsink 51 Heat dissipation fin

Claims

1. A base plate superimposed on a substrate and used as a ground, a metal plate provided on the substrate, the metal plate having an opening provided at a position facing an electronic component protruding from the substrate toward the base plate, the opening being along an outline of the electronic component in a plan view; one or more frames each having an opening facing the opening and having the same shape as the opening, and each having a predetermined thickness; a bottom portion that covers the opening provided in the frame body, A base plate is formed by stacking the metal plate, the one or more frame bodies, and the bottom portion in this order.

2. The one or more frame bodies are stacked in such a number that the length by which the electronic components protrude from the board is equal to or less than a length based on the thickness of the metal plate and the predetermined thickness of the frame body.

2. The base plate according to claim 1.

3. The base plate is made of aluminum 3. The base plate according to claim 1 or 2.

4. The board is a communication board.

3. The base plate according to claim 1 or 2.

5. The communication board and base plate are mounted on a HAPS (High Altitude Platform Station) unmanned aircraft.

5. The base plate according to claim 4.

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