Electronic device

Abstract

An electronic device includes: a circuit board on which an electronic component is mounted; and the shell is made of metal, and a circuit board is arranged in the shell. The housing has: an inner wall on which the circuit board is mounted and which surrounds the electronic component; and at least one protrusion disposed on a surface of the inner wall facing the circuit board and in metal-to-metal contact with the circuit board.

Description

Technical Field

[0001] This invention relates to an electronic device including a circuit board on which electronic components are mounted. Background Technology

[0002] Conventionally, techniques for reducing the impact of electromagnetic waves on circuit components have been proposed in electronic devices (for example, see Japanese Unexamined Patent Application No. 2008-79200 (Patent Document 1)). Patent Document 1 discloses that by providing an antenna element separate from the circuit board, the noise impact on circuit components due to radio wave radiation from the antenna element can be reduced. In Patent Document 1, the antenna element is provided on the inner bottom surface of the housing. Since the circuit board is fixed to ribs adhered to the inner bottom surface of the housing, the circuit board is configured to be separate from the antenna element in a direction orthogonal to the circuit board.

[0003] In another method besides the configuration in Patent Document 1, electromagnetic noise can be shielded using metal-to-metal contact between the circuit board and the housing on which the circuit board is disposed. In such a configuration, for example, consider a arrangement of leaf springs and a screw-fixed configuration, to reliably achieve metal-to-metal contact between the circuit board and the housing at the target location.

[0004] However, if leaf springs and screws are arranged one by one at the target locations to achieve metal-to-metal contact between the circuit board and the housing, there are concerns that the increased number of leaf springs or screws used would increase the manufacturing cost of the electronic device. Furthermore, the configuration using leaf springs or screws requires a larger area to arrange these materials, which could lead to an increase in dead zones on the circuit board. If dead zones increase, the efficiency of placing electronic components on the circuit board may decrease. Summary of the Invention

[0005] According to one aspect of the invention, an electronic device includes: a circuit board on which electronic components are mounted; and a housing made of metal having the circuit board disposed inside, the housing having: an inner wall on which the circuit board is mounted and surrounding the electronic components; and at least one protrusion disposed on a surface of the inner wall facing the circuit board and in metal-to-metal contact with the circuit board.

[0006] The purpose of this invention is to provide a technique for properly shielding electromagnetic noise using metal-to-metal contact between a circuit board and a housing.

[0007] These and other objects, features, aspects, and advantages of the invention will become more apparent from the following detailed description of the invention in conjunction with the accompanying drawings. Attached Figure Description

[0008] Figure 1This is a perspective view showing the schematic structure of an electronic device;

[0009] Figure 2 yes Figure 1 An exploded perspective view of the electronic device shown;

[0010] Figure 3 This is a perspective view showing a schematic structure of the housing included in an electronic device;

[0011] Figure 4 This is a plan view showing a schematic structure of the housing included in an electronic device;

[0012] Figure 5 It is along Figure 1 A schematic cross-sectional view of the electronic device with line VV in the diagram;

[0013] Figure 6 It is along Figure 1 A schematic cross-sectional view of the electronic device along line VI-VI;

[0014] Figure 7 It is along Figure 1 A schematic cross-sectional view of the electronic device of line VII-VII in the diagram;

[0015] Figure 8 This is a schematic cross-sectional view showing a pin mark formed on a partition wall, as a comparative example of a first partition wall according to this embodiment; and

[0016] Figure 9 This is a cross-sectional view showing a schematic structure of a protrusion provided on the inner wall. Detailed Implementation

[0017] In the following description, exemplary embodiments of the present invention will be described in detail with reference to the accompanying drawings. The drawings appropriately illustrate an XYZ coordinate system as a three-dimensional orthogonal coordinate system. In the following description, the X-axis direction is the front-back direction, the Y-axis direction is the left-right direction, and the Z-axis direction is the up-down direction. The positive X-axis side is the front side, the negative X-axis side is the back side, the positive Y-axis side is the right side, the negative Y-axis side is the left side, the positive Z-axis side is the top side, and the negative Z-axis side is the bottom side. However, these directions are for illustration only and do not limit actual positional relationships and orientations.

[0018] In the XYZ coordinate system, circuit board 2 (see reference 2) described later Figure 2 The main surface of circuit board 2 is oriented in the XY plane, and the thickness direction of circuit board 2 is oriented in the Z-axis direction. "Main surface" refers to one of the front and back surfaces of circuit board 2, excluding the side surfaces along the thickness direction of circuit board 2. "Main surface direction" refers to the direction parallel to the main surface.

[0019] <1. Overview of Electronic Devices>

[0020] Figure 1 This is a perspective view showing a schematic configuration of the electronic device 100 according to this embodiment. Figure 2 yes Figure 1 The diagram shows an exploded perspective view of the electronic device 100. The electronic device 100 is an ECU (Electronic Control Unit) installed in a vehicle (not shown). The ECU controls the electronic device installed in the vehicle. However, the electronic device of the present invention is not limited to an ECU and can be other electronic devices. The electronic device of the present invention can be an electronic device installed in a device other than a vehicle.

[0021] like Figure 1 and Figure 2 As shown, the electronic device 100 includes a housing 1, a circuit board 2, and a cover 3. The housing 1 is a box with an opening 1a on its top surface. The circuit board 2 is disposed inside the housing 1. In other words, the housing 1 houses the circuit board 2. The cover 3 is disposed above the circuit board 2 disposed inside the housing 1 and covers the circuit board 2. The cover 3 is made of metal, specifically a pressed material obtained by pressing metal sheets. The circuit board 2 and the cover 3, arranged vertically overlapping each other, are secured to the housing 1 using a plurality of fastening members 4. Specifically, the plurality of fastening members 4 are screws. The circuit board 2 and the cover 3 are jointly fastened to the housing 1 using the plurality of fastening members 4.

[0022] Circuit board 2 is a board material extending along the XY plane. Electronic component 21 (see description below) is mounted on circuit board 2. Figure 5 Examples of electronic components 21 include various electronic components containing IC (integrated circuit) chips. A connector 22 is mounted on the circuit board 2. That is, the electronic device 100 includes a connector 22 mounted on the circuit board 2. The connector 22 is electrically connected to an external device.

[0023] Specifically, connector 22 includes a power connector 221 and a signal connector 222. The power connector 221 connects to a power cord (not shown) that provides power. The power cord is, for example, a power supply cable electrically connected to a power supply device. Because of the power connector 221, power is supplied to the circuit board 2.

[0024] Signal connector 222 is connected to a signal line (not shown) through which signals are transmitted. Examples of signal lines include a signal transmitter located outside the electronic device 100 for transmitting signals, and a signal cable connected to a signal receiver for receiving signals. The signal transmitter and signal receiver can be configured as a single device for transmitting and receiving signals. Because of the signal connector 222, signal input from outside the electronic device 100 to the circuit board 2 and signal output from the circuit board 2 to outside the electronic device 100 can be performed.

[0025] <2. Shielding Structure for Electromagnetic Wave Noise>

[0026] Next, the electromagnetic noise shielding structure in the electronic device 100 configured as described above will be described.

[0027] [2-1. Overview]

[0028] Figure 3 This is a perspective view showing a schematic configuration of the housing 1 included in the electronic device 100. Figure 4 This is a plan view showing a schematic configuration of the housing 1 included in the electronic device 100. The housing 1 is made of metal. The housing 1 is a molded part. Specifically, the housing 1 is a die-cast molded part. More specifically, the housing 1 is an aluminum die-cast molded part configured using an aluminum alloy.

[0029] like Figure 3 and Figure 4 As shown, the shell 1 has a rectangular shape in the plan view. The shell 1 has a rectangular bottom wall 11 and a rectangular outer peripheral wall 12 in the plan view. The outer peripheral wall 12 extends upward from the upper circumference of the bottom wall 11. Specifically, the outer peripheral wall 12 includes a front outer wall 12a, a rear outer wall 12b, a left outer wall 12c, and a right outer wall 12d. The front outer wall 12a extends upward from the upper front end of the bottom wall 11. The rear outer wall 12b extends upward from the upper rear end of the bottom wall 11. The left outer wall 12c extends upward from the upper left end of the bottom wall 11. The right outer wall 12d extends upward from the upper right end of the bottom wall 11.

[0030] The front outer wall 12a is provided with two connector openings 121 through which the power connector 221 and the signal connector 222 are exposed to the outside of the electronic device 100. The two connector openings 121 are spaced apart in a row in the left-right direction. Specifically, each of the two connector openings 121 is formed by cutting out a specific rectangular area including the upper edge of the front outer wall 12a in the front view, and the cut-out area (specific area) varies accordingly according to the size of the connector 22. In this embodiment, since the size of the power connector 221 is different from the size of the signal connector 222, the sizes of the two connector openings 121 are also different.

[0031] like Figure 3 and Figure 4 As shown, the housing 1 has an inner wall 13. The circuit board 2 is mounted on the inner wall 13. Like the outer peripheral wall 12, the inner wall 13 extends upward from the upper surface of the bottom wall 11. However, the upper surface of the inner wall 13 is positioned lower (below) than the upper surface of the outer peripheral wall 12. Figure 4 In the diagram, the shaded area with diagonal lines corresponds to the upper surface of the inner wall 13. Since the upper surface of the inner wall 13 is positioned lower than the upper surface of the outer peripheral wall 12, the circuit board 2 mounted on the inner wall 13 is located inside the housing 1.

[0032] A portion of the inner wall 13 is configured to protrude from the outer peripheral wall 12 toward the inside of the housing 1. The inner wall 13 includes a front inner wall 13a, a rear inner wall 13b, a left inner wall 13c, and a right inner wall 13d. The front inner wall 13a is configured to protrude rearward from the front outer wall 12a. The front inner wall 13a is not located in the portion of the front outer wall 12a where each connector opening 121 is provided. The rear inner wall 13b is configured to protrude forward from the rear outer wall 12b. The left inner wall 13c is configured to protrude to the right from the left outer wall 12c. The right inner wall 13d is configured to protrude to the left from the right outer wall 12d.

[0033] The left end of the front inner wall 13a connects to the front end of the left inner wall 13c to form a first inner wall angle 131. The right end of the front inner wall 13a connects to the front end of the right inner wall 13d to form a second inner wall angle 132. The left end of the rear inner wall 13b connects to the rear end of the left inner wall 13c to form a third inner wall angle 133. The right end of the rear inner wall 13b connects to the rear end of the right inner wall 13d to form a fourth inner wall angle 134.

[0034] The inner wall 13 also includes a first partition wall 13e and a second partition wall 13f. The first partition wall 13e and the second partition wall 13f divide the space inside the housing 1 into multiple spaces. The first partition wall 13e extends in the left-right direction. The first partition wall 13e connects the position between the front end and the rear end of the left inner wall 13c to the position between the front end and the rear end of the right inner wall 13d. The second partition wall 13f extends in the front-back direction. The second partition wall 13f connects the position between the left end and the right end of the front inner wall 13a to the position between the left end and the right end of the first partition wall 13e.

[0035] Figure 5 It is along Figure 1 A schematic cross-sectional view of the electronic device 100 with line VV in the middle. Figure 6 It is along Figure 1 A schematic cross-sectional view of the electronic device 100 along line VI-VI. Figure 7 It is along Figure 1 A schematic cross-sectional view of the electronic device 100 along line VII-VII. (See diagram below.) Figures 5 to 7 As shown, circuit board 2 is mounted on inner wall 13.

[0036] Specifically, the upper surfaces of the front inner wall 13a, rear inner wall 13b, left inner wall 13c, right inner wall 13d, first partition wall 13e, and second partition wall 13f are at the same height in the vertical direction. The circuit board 2 is mounted on the upper surfaces of the front inner wall 13a, rear inner wall 13b, left inner wall 13c, right inner wall 13d, first partition wall 13e, and second partition wall 13f.

[0037] A grounding portion (not shown) is provided on the lower surface of circuit board 2, facing the upper surface of the front inner wall 13a, rear inner wall 13b, left inner wall 13c, right inner wall 13d, first partition wall 13e, and second partition wall 13f. Therefore, the front inner wall 13a, rear inner wall 13b, left inner wall 13c, right inner wall 13d, first partition wall 13e, and second partition wall 13f are in metal-to-metal contact with circuit board 2. In other words, the inner wall 13 is in metal-to-metal contact with circuit board 2.

[0038] like Figures 3 to 7 As shown, in the electronic device 100, the electronic component 21, mounted on the lower surface of the circuit board 2, is disposed in a space surrounded by the inner wall 13. Specifically, the electronic component 21 is disposed in a first space S1 surrounded by the rear inner wall 13b, the left inner wall 13c, the right inner wall 13d, and the first partition wall 13e.

[0039] A power connector 221, mounted on the lower surface of circuit board 2, is disposed in a second space S2 surrounded by a front inner wall 13a, a left inner wall 13c, a first partition wall 13e, and a second partition wall 13f. However, the power connector 221 is exposed to the outside of the electronic device 100 through a connector opening 121.

[0040] Although detailed illustrations are omitted, the signal connector 222, mounted on the lower surface of the circuit board 2, is disposed in a third space S3 surrounded by the front inner wall 13a, the right inner wall 13d, the first partition wall 13e, and the second partition wall 13f. However, the signal connector 222 is exposed to the outside of the electronic device 100 through a connector opening 121.

[0041] like Figures 5 to 7 As shown, the circuit board 2 is secured to the housing 1 together with a cover 3 using multiple fastening members 4. The cover 3 is disposed on one side of the first surface (upper surface) 2b of the circuit board 2, which is the opposite surface of the second surface (lower surface) 2a of the circuit board 2 facing the inner wall 13. Specifically, the circuit board 2 is covered from above by a metal cover 3 and is secured to the housing 1 together with the metal cover 3 by multiple fastening members 4 including metal screws. Thus, the circuit board 2, disposed inside the housing 1 and covered by the cover 3, is disposed in a space surrounded by metal material.

[0042] As described above, in the electronic device 100 according to this embodiment, the electronic component 21 to be mounted on the circuit board 2 is surrounded by an inner wall 13 included in the housing 1 made of metal. The inner wall 13 is in metal-to-metal contact with the grounding portion provided on the circuit board 2. Therefore, in the configuration according to this embodiment, grounding is strengthened by using the metal-to-metal contact between the circuit board 2 and the housing 1. As a result, an electromagnetic noise shielding structure can be applied to the electronic component 21 mounted on the circuit board 2. That is, in the electronic device 100 according to this embodiment, the electronic component 21 can be prevented from being affected by electromagnetic noise entering from the outside, and electromagnetic noise can be prevented from radiating from the electronic component 21 to the outside.

[0043] In this embodiment, there is a concern that electromagnetic noise generated by the connector 22 (specifically, the power connector 221) included in the electronic device 100 may affect the electronic component 22. However, the inner wall 13 surrounding the electronic component 21 includes a partition wall (first partition wall) 13e that separates the connector 22 from the electronic component 21. In other words, the first space S1 where the electronic component 21 is disposed, and the second space S2 and the third space S3 where the connector 22 is disposed, are separated by the first partition wall 13e. In this configuration, electromagnetic noise generated by the connector 22 can be prevented from affecting the electronic component 21.

[0044] [2-2. Details]

[0045] As described above, housing 1 is a die-cast molded part. Therefore, housing 1 is manufactured by the following steps: pressing molten metal (aluminum alloy in this example) into a mold; and demolding the solid molded part from the mold after pressing the molten metal into the mold. In the demolding step, the molded part (housing 1) is removed from the mold by pressing it with an extrusion pin (not shown). When assuming housing 1 as a molded part... Figure 4 When the orientation shown is set in the mold, the housing 1 is extruded by extrusion pins along the negative Z direction (in the depth direction of this page). The extrusion pins are, for example, columnar, and multiple extraction pins are typically used in the demolding step.

[0046] In this embodiment, when the housing 1 has a thin and long partition wall (specifically, the first partition wall 13e), the partition wall is prone to deformation when the housing 1 is removed from the mold. To address this, during the demolding step, the molded part (housing 1) is removed such that the first partition wall 13e is pressed by some of the extrusion pins of the extrusion molded part (housing 1). This configuration prevents deformation of the first partition wall 13e.

[0047] In this embodiment, among the plurality of extrusion pins, the extrusion pins that extrude the portion of the housing 1 other than the first partition wall 13e extrude the portion of the housing 1 other than the inner wall 13. However, the extraction pins that extrude the portion of the housing 1 other than the first partition wall 13e can be used to extrude the inner wall 13 other than the first partition wall 13e (such as the second partition wall 13f). In this embodiment, there are a plurality of extrusion pins for extruding the first partition wall 13e.

[0048] Incidentally, when extrusion is performed by multiple extrusion pins during the demolding process, pin marks are usually left on the housing 1 due to the extrusion by multiple extrusion pins. Figure 8 This is a schematic cross-sectional view showing a pin mark 14 formed on a partition wall 13eA, which is shown as a comparative example of a first partition wall 13e according to this embodiment. Figure 8 As shown, the pin mark 14 typically has a concave shape.

[0049] In this embodiment, as described above, to prevent electromagnetic noise from affecting the electronic component 21, a metal-to-metal contact is formed between the inner wall 13 and the circuit board 2. If a metal-to-metal contact is formed on the upper surface of the first partition wall 13e... Figure 8 As shown, the recessed pin mark 14 may result in insufficient metal-to-metal contact between the first partition wall 13e and the circuit board 2. Consequently, for example, electromagnetic noise generated in the power connector 221 may enter the first space S1 where the electronic component 21 is located, which could affect the electronic component 21.

[0050] With this in mind, in this embodiment, as Figure 9 As shown, the housing 1 has a protrusion 15, which is disposed on the surface (upper surface) of the inner wall 13 facing the circuit board 2 and is in metal-to-metal contact with the circuit board 2. Figure 9 This is a cross-sectional view showing a schematic configuration of the protrusion 15 provided on the inner wall 13. Specifically, the protrusion 15 is in metal-to-metal contact with the ground portion provided on the circuit board 2. The protrusion 15 preferably protrudes slightly relative to the upper surface of the inner wall 13.

[0051] Thus, when the protrusion 15 is provided on the upper surface of the inner wall 13, the protrusion 15 can be used to facilitate metal-to-metal contact between the inner wall 13 and the circuit board 2 mounted on the inner wall 13 at the target location. Even in this configuration, such as when a pin mark 14 with a recessed shape is formed, the metal-to-metal contact between the inner wall 13 and the circuit board 2 may become insufficient. However, it is difficult to ensure a surface parallel to the main surface of the circuit board 2 over a large area of ​​the upper surface of the inner wall 13. Therefore, as in this embodiment, by providing the protrusion 15, metal-to-metal contact is preferably reliably obtained at the target location. When metal-to-metal contact is obtained at the target location, other measures for shielding electromagnetic noise, as described later, are easily implemented. Furthermore, when the protrusion 15 is provided on the upper surface of the inner wall 13, the number of leaf springs and screws used, which are arranged to obtain metal-to-metal contact between the housing 1 and the circuit board 2 at the target location, can be minimized as much as possible. Therefore, dead zones caused by the arrangement of leaf springs and screws can be suppressed as much as possible.

[0052] Figure 4 The circle 16, indicated by a dashed line, shows the position of the extrusion pin that pushes against the inner wall 13. (As shown...) Figure 4 As shown, the protrusion 15 is positioned at the location of the extrusion pin that pushes the housing 1 when it is removed from the mold. This configuration suppresses the formation of pin marks 14 on the inner wall 13 that are recessed relative to the upper surface of the inner wall 13 as described above. With this configuration, the tolerance of the amount of protrusion of the protrusion 15 relative to the upper surface of the inner wall 13 after being extruded by the extrusion pin can be controlled. Tolerance control can be implemented, for example, ensuring that the amount of protrusion is 0 mm or more and 0.2 mm or less.

[0053] In this embodiment, the protrusion 15 is provided on the first partition wall 13e that separates the connector 22 from the electronic component 21. With this configuration, an electromagnetic noise shielding structure can be appropriately applied to the portion of the inner wall 13 that is pressed by the extrusion pin when the housing 1 is removed from the mold. According to this configuration, an electromagnetic noise shielding structure can be appropriately applied to portions where electromagnetic noise is easily generated due to the presence of the power connector 221, etc.

[0054] The protrusion 15 may be provided on the portion of the inner wall 13 other than the first partition wall 13e. The protrusion 15 is not necessarily provided on the portion of the inner wall 13 that is pressed by the compression pin, and may also be provided on the portion of the inner wall 13 that is not pressed by the compression pin.

[0055] like Figure 4As shown, in this embodiment, a plurality of protrusions 15 are provided at intervals on the inner wall 13 (specifically, the first partition wall 13e). Thus, the electromagnetic noise shielding structure can also be appropriately applied to long extension walls (such as the first partition wall 13e) with multiple locations where they are pushed by compression pins.

[0056] In this embodiment, when a plurality of protrusions 15 are spaced apart on the inner wall 13, each interval between adjacent protrusions 15 preferably corresponds to a spacing for shielding electromagnetic noise at at least one location. The spacing for shielding electromagnetic noise is determined by the wavelength of the electromagnetic noise that should be shielded. The electromagnetic noise that should be shielded is appropriately determined, for example, by the design of the electronic device 100.

[0057] When the position of the protrusion 15 matches the spacing required to shield electromagnetic noise, the following effect is achieved. When metal-to-metal contact occurs between the circuit board 2 and the inner wall 13, even if a gap is generated between the circuit board 2 and the inner wall 13 (in the vertical direction) due to the presence of the protrusion 15, electromagnetic noise can be prevented from entering the space where the electronic components 21 are provided (the first space S1 in this embodiment).

[0058] The housing 1 preferably has a fixing portion 17, which uses a plurality of fastening members 4 between at least one set of adjacent protrusions 15 to fix the circuit board 2 to the inner wall 13. As described above, in this embodiment, the plurality of fastening members 4 are screws. Therefore, according to this embodiment, screw holes 171 are provided in the fixing portion 17. In other words, the fixing portion 17 is a screw fixing portion.

[0059] Thus, when a fixing part 17 is provided in addition to the protrusion 15, the area of ​​metal-to-metal contact between the inner wall 13 and the circuit board 2 at the target position is increased. Furthermore, it prevents the circuit board 2 from floating relative to the inner wall 13 between adjacent protrusions 15.

[0060] In this embodiment, in addition to the spaces between adjacent protrusions 15, multiple locations are provided where the circuit board 2 is fixed to the inner wall 13 using multiple fastening members 4, while simultaneously creating metal-to-metal contact between the circuit board 2 and the inner wall 13. For example, such fixing locations include positions corresponding to the four corners of the circuit board 2. The positions corresponding to the four corners of the circuit board 2 are the aforementioned first inner wall corner 131, second inner wall corner 132, third inner wall corner 133, and fourth inner wall corner 134 (see reference). Figure 4Because multiple fixing positions using multiple fastening members 4 are provided, even if the circuit board 2 bends, metal-to-metal contact between the circuit board 2 and the inner wall 13 can be achieved at the target location. Metal-to-metal contact is easily achieved at the location where the protrusion 15 is provided, eliminating the need for fixing with multiple fastening members 4. Therefore, in this embodiment, providing an excessive number of fixing parts 17 can be prevented.

[0061] In this embodiment, such as Figure 4 As shown, the fixing part 17 is provided at the intersection (intersection) where the first partition wall 13e and the second partition wall 13f connect to each other. By providing the fixing part 17 at this location, a strong metal-to-metal contact between the inner wall 13 and the circuit board 2 can be obtained between the two spaces S2 and S3 where the connector 22 is located. For example, electromagnetic noise generated by the power connector 221 can be suppressed from entering the space S3 where the signal connector 222 is located. Furthermore, since the fixing part 17 is provided at the intersection of these two walls, it is located in a position with high rigidity.

[0062] <4. Focus>

[0063] In addition to the embodiments described above, the various technical features disclosed in this specification can be modified in various ways without departing from the spirit of the inventive art. The features of the preferred embodiments described above and their modifications can be appropriately combined, as long as no conflict occurs.

[0064] Although the invention has been shown and described in detail, the foregoing description is illustrative in all respects and not restrictive. Therefore, it is understood that many other modifications and variations can be devised without departing from the scope of the invention.

Claims

1.An electronic device comprising: a circuit board on which an electronic component is mounted; and a case made of metal, inside of which the circuit board is disposed, the case having: an inner wall on which the circuit board is mounted and which surrounds the electronic component; and at least one protrusion disposed on a surface of the inner wall facing the circuit board and in metal-to-metal contact with the circuit board. 2.The electronic device of claim 1, wherein, the case is a molded part, and the at least one protrusion is disposed at a position where a press pin that pushes the case when the case is taken out of a mold. 3.The electronic device of claim 2, wherein, the at least one protrusion includes a plurality of protrusions, and the plurality of protrusions are disposed at intervals on the inner wall. 4.The electronic device of claim 3, wherein, at least one interval between adjacent protrusions among the plurality of protrusions corresponds to a pitch that shields electromagnetic wave noise. 5.The electronic device of claim 3, wherein, the case has at least one fixing portion that fixes the circuit board to the inner wall using a fastening member between adjacent protrusions among the plurality of protrusions. 6.The electronic device of claim 5, wherein, the circuit board has a first surface and a second surface that is an opposite surface of the first surface and faces the inner wall, and the circuit board is fixed to the case using a plurality of fastening members together with a cover disposed on one side of the first surface. 7.The electronic device of any one of claims 1 to 6, further comprising: a connector mounted on the circuit board, wherein, the inner wall includes a partition wall that separates the connector from the electronic component, and the at least one protrusion is disposed on the partition wall. 8.The electronic device of claim 7, further comprising: a power connector connected to a power cord that provides power.

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