JP7567557B2 - Control unit structure - Google Patents

Description

The technology disclosed herein belongs to the technical field of control unit structure.

It has long been known that electromagnetic waves generated by electronic devices can become noise and affect the operation of peripheral devices. For this reason, methods for reducing the electromagnetic waves generated by electronic devices have been studied.

For example, the output noise reduction device described in Patent Document 1 includes a metal housing that houses an electronic device and the output noise reduction device, a conductive bar made of a conductive material, one end of which serves as a connection terminal for connecting to an output terminal of the electronic device and the other end as an output terminal, a magnetic core made of a magnetic material and having a through hole through which the conductive bar passes, a capacitive element located at least either between the magnetic core and the output terminal or between the magnetic core and the connection terminal, connecting the conductive bar and the metal housing, and a mounting board, one side of which serves as a mounting surface for mounting the capacitive element and the other side of which serves as a metal surface at the same potential as the metal housing and to which one terminal of the capacitive element is connected.

JP 2018-19512 A

Incidentally, some electromagnetic waves generated by electronic devices are caused by an electric charge building up between an integrated circuit and a conductive housing. This type of electromagnetic wave does not pass through the noise reduction device, but is emitted outside while traveling through the conductive housing, affecting peripheral devices.

One way to reduce the range in which electromagnetic waves are generated is to return (loop) the charge generated between the integrated circuit and the conductive housing back to the board via the shortest possible path from the housing through a conductive material. However, in recent years, the density of components mounted on boards has increased, making it difficult to mount new components to shorten the loop near the integrated circuit. For this reason, in order to implement this measure, the board size must be increased.

The technology disclosed here has been developed in light of these issues, and its purpose is to reduce as much as possible the electromagnetic waves emitted from the housing that houses the integrated circuit, without increasing the size of the board.

In order to solve the above problem, the technology disclosed herein is directed to a control unit structure, and includes a housing made of a conductive material and having at least a pair of flat plate portions facing each other, a board on which an integrated circuit is mounted and which is accommodated in the housing so as to be parallel to the flat plate portions, and a conductive board fixture that extends in a direction intersecting the direction in which the board extends and fixes the board to one of the flat plate portions, the board fixture being positioned in the vicinity of the integrated circuit when viewed from a direction perpendicular to the surface of the board, and the other flat plate portion and the board fixture being electrically connected.

With this configuration, the board fixture located near the integrated circuit is conductive and electrically connected to the housing, so that the current caused by the charge generated between the integrated circuit and the housing flows from the housing through the board fixture and back to the board. This makes it possible to narrow the area through which the current passes through the housing, and to reduce the electromagnetic waves emitted from the housing.

In addition, by using the board fixing device, there is no need to place additional conductive material on the board to protect against electromagnetic waves, which helps prevent the housing from becoming too large.

In one embodiment of the control unit structure, the substrate fixture is axially shaped and has one end fixed to one of the flat plate portions, and the other end of the substrate fixture and the other flat plate portion are electrically connected by a conductive connecting member.

With this configuration, because the board fixture is axially shaped, the area on the board where the board fixture is placed can be made as small as possible. This makes it easier to bring the integrated circuit and the board fixture closer together. As a result, the electromagnetic waves emitted from the housing can be more effectively reduced.

In one embodiment, the connecting member may be configured such that one end of the connecting member is an axial member that passes through the other flat plate portion and is attached to the other end of the substrate fixing device.

This configuration allows the housing and the board fixing device to be firmly connected, ensuring a current path. In addition, because the board is fixed to both of the pair of flat plate portions, the board can be firmly fixed to the housing.

In another embodiment of the control unit, the board fixing device is axially shaped, with one end penetrating the one flat plate portion and the board and attached to a conductive fixture provided in the housing, and the board fixing device and the other flat plate portion are electrically connected to each other by a conductive shaft-shaped member with one end penetrating the other flat plate portion and attached to the fixture.

Even with this configuration, the housing and the board fixing device can be firmly joined, and a current path can be secured. In addition, because the board is fixed to both of the pair of flat plate portions, the board can be firmly fixed to the housing.

As explained above, the technology disclosed herein can reduce as much as possible the electromagnetic waves emitted from the housing that houses the integrated circuit.

FIG. 1 is a plan view of a control unit having a unit structure according to a first embodiment. FIG. 2 is a cross-sectional view taken along line II-II of FIG. FIG. 3 is an enlarged cross-sectional view showing the periphery of the integrated circuit. FIG. 4 is a schematic diagram showing a current loop. FIG. 5 is a cross-sectional view corresponding to FIG. 2 of a control unit having a unit structure according to the second embodiment. FIG. 6 is a cross-sectional view corresponding to FIG. 2 of a control unit having a unit structure according to a third embodiment.

An exemplary embodiment will be described in detail below with reference to the drawings.

(Embodiment 1)
1 shows a control unit 1 having a unit structure according to the present embodiment 1. The control unit 1 is a control unit mounted on a moving body such as a vehicle.

The control unit 1 has a box-shaped housing 10 and a board 20 housed within the housing 10. The board 20 is fixed to the housing 10 by a plurality of (here, five) board fixing devices 30. The board fixing devices 30 are respectively arranged at the four corners and the center of the board 20. A connector 100 is provided in a part of the housing 10 and is electrically connected to an integrated circuit 21 and the like mounted on the board 20. The integrated circuit 21 communicates with an external device via the connector 100. The arrangement and number of the board fixing devices 30 are not particularly limited.

The housing 10 is made of a conductive material, specifically a metal, for example, aluminum. As shown in FIG. 2, the housing 10 has a pair of flat plate portions 11 that face each other. The flat plate portions 11 are arranged parallel to each other. The size of the housing 10 in a plan view, i.e., the area of the flat plate portions 11, is approximately 150 mm x 200 mm.

As shown in FIG. 2, the substrate 20 is a substrate on which an integrated circuit 21 is mounted. In addition to the integrated circuit 21, mounted components 22 such as a capacitor are also mounted on the substrate 20. The substrate 20 is, for example, a glass epoxy substrate, and copper wiring 23 is arranged in multiple layers within the substrate 20. The wiring 23 electrically connects the integrated circuit 21, the mounted components 22, and the connector 100 to each other. The wiring 23 is electrically connected to each other by vias. The integrated circuit 21 and the mounted components 22 are mounted on one side of the substrate 20. The integrated circuit 21 is electrically connected to the wiring 23 by multiple pins 21a (see FIG. 3). The substrate 20 is accommodated in the housing 10 so as to be parallel to each flat plate portion 11.

Of the pair of flat plate portions 11, the flat plate portion 11 facing the integrated circuit 21 (hereinafter referred to as the first flat plate portion 11a) has a protruding portion 12 that protrudes toward the integrated circuit 21 at the portion facing the integrated circuit 21. The protruding portion 12 protrudes up to near the surface of the integrated circuit 21. As shown in FIG. 3, an insulating heat dissipation sheet 13 is provided between the protruding portion 12 and the integrated circuit 21. This heat dissipation sheet 13 thermally connects the integrated circuit 21 and the first flat plate portion 11a, allowing heat to be dissipated from the integrated circuit 21 to the housing 10.

As shown in FIG. 2, the substrate fixing device 30 is axially shaped. Specifically, the substrate fixing device 30 is composed of a screw. The substrate fixing device 30 is composed of a conductive material with as low an electrical resistivity as possible, and is preferably composed of a conductive material with an electrical resistivity similar to that of the housing 10. This does not prevent the substrate fixing device 30 from being composed of a conductive material with an electrical resistivity higher than that of the housing 10.

The substrate fixture 30 extends in a direction intersecting the direction in which the substrate 20 spreads, more specifically, in a direction perpendicular to the surface of the substrate 20. One end of the substrate fixture 30 penetrates the substrate 20 and is fixed to the flat plate portion 11 (hereinafter referred to as the second flat plate portion 11b) facing the first flat plate portion 11a. The second flat plate portion 11b has a fixing portion 14 to which one end of the substrate fixture 30 is fixed. The fixing portion 14 has a shape that protrudes toward the inside of the housing 10. The substrate fixture 30 is passed through the substrate 20, one end of the substrate fixture 30 is fastened to the fixing portion 14, and the substrate 20 is sandwiched between the head portion 31 provided at the other end of the substrate fixture 30 and the fixing portion 14, thereby fixing the substrate 20 to the housing 10.

As shown in Figures 1 and 2, at least one is placed near the integrated circuit 21. The distance between the substrate fixture 30 closest to the integrated circuit 21 and the integrated circuit 21 is approximately 10 to 20 mm.

The first flat plate portion 11a is electrically connected to the substrate fixture 30. Specifically, the first flat plate portion 11a and the head portion 31 of the substrate fixture 30 are connected by a conductive gasket 40. The gasket 40 is columnar or axial, and the gasket 40 and the first flat plate portion 11a, and the gasket 40 and the head portion 31 are bonded by a conductive adhesive. The gasket 40 is preferably made of a material with the same electrical resistivity as the substrate fixture 30. The gasket 40 may be made of a conductive material with a lower electrical resistivity than the substrate fixture 30, or may be made of a conductive material with a higher electrical resistivity than the substrate fixture 30.

Here, as in the present embodiment 1, when a part of the housing 10 (particularly the protruding portion 12) and the integrated circuit 21 are close to each other, as shown in FIG. 3, the area between the housing 10 and the integrated circuit 21 behaves like a capacitor. In particular, when an insulating heat dissipation sheet 13 is provided as in the present embodiment 1, a capacitance is generated between the housing 10 and the integrated circuit 21. When a capacitance is generated in this way, charge moves between the integrated circuit 21 and the housing 10 through this capacitance. When a current flows through the housing 10 due to this charge movement, an electromagnetic wave is generated from the housing 10. When an electronic device arranged around the control unit 1 receives this electromagnetic wave, noise is generated in the electronic device. In particular, in the case of the control unit 1 mounted on a moving body as in the present embodiment 1, the radar installed on the moving body may receive the electromagnetic wave, which may reduce the sensing accuracy of the radar. Note that the capacitor shown in FIG. 3 is shown virtually for the purpose of explanation, and the capacitor is not arranged on the heat dissipation sheet 13.

In contrast, in this embodiment 1, the first flat plate portion 11a and the board fixing tool 30 arranged near the integrated circuit 21 are electrically connected, so that the electromagnetic waves can be reduced as much as possible. As shown in FIG. 4, if a conductive member CM (shown by a dashed line in FIG. 4) is arranged to return the current that is the source of the electromagnetic waves to the board 20, the conductive member CM needs to be arranged in a part of the board 20 where there are no mounted components 22, such as the end of the board 20. In this case, as shown by a dashed line in FIG. 4, the current passes through a wide range of the first flat plate portion 11a, and then passes through the conductive member CM and the wiring 23 and returns to the integrated circuit 21. Therefore, the area in which electromagnetic waves that become noise can be emitted is widened. If the conductive member CM is arranged near the integrated circuit 21 in order to narrow the range in which the current passes through the first flat plate portion 11a, the board 20 needs to be made larger, which leads to an increase in the size of the control unit 1. On the other hand, in this embodiment 1, as shown by the solid line in FIG. 4, the current passes from the first flat plate portion 11a through the gasket 40 and the board fixing device 30, then passes through the wiring 23 and returns to the integrated circuit 21. This makes it possible to significantly narrow the range through which the current passes through the first flat plate portion 11a, thereby narrowing the area in which electromagnetic waves can be emitted. As a result, it is possible to reduce the electromagnetic waves emitted from the housing 10 as much as possible. In addition, since there is no need to provide a separate conductive member CM, there is no need to enlarge the board 20, and the size of the control unit 1 can also be suppressed.

In addition, in this embodiment 1, since the substrate fixing device 30 is axially shaped, the area on the substrate 20 where the substrate fixing device 30 is arranged can be made as small as possible. This makes it easier to bring the integrated circuit 21 and the substrate fixing device 30 closer together. As a result, the electromagnetic waves emitted from the housing 10 can be more effectively reduced.

(Embodiment 2)
Hereinafter, the second embodiment will be described in detail with reference to the drawings. In the following description, the same reference numerals will be used to designate the same parts as those in the first embodiment, and detailed description thereof will be omitted.

In this embodiment 2, the configuration of the connecting member that electrically connects the first flat plate portion 11a and the substrate fixture 30 is different from that of the above-mentioned embodiment 1. Specifically, in this embodiment 2, the connecting member is configured with a screw 240 (shaft-shaped fastening member) whose one end penetrates the first flat plate portion 11a and is fastened to the other end of the substrate fixture 30. A screw hole into which one end of the screw 240 is fastened is formed in the head portion 31 of the substrate fixture 30. The other end of the screw 240 is in contact with the first flat plate portion 11a and is electrically connected. Conductive grease may be provided between the screw 240 and the first flat plate portion 11a. The screw 240 is configured with a conductive material with as low an electrical resistivity as possible, and is preferably configured with the same material as the substrate fixture 30. This does not prevent the screw 240 from being configured with a conductive material different from that of the substrate fixture 30.

Even in the configuration of this embodiment 2, the board fixing device 30 arranged near the integrated circuit 21 and the first flat plate portion 11a are electrically connected by the screw 240, so that the electromagnetic waves emitted from the housing 10 that houses the integrated circuit 21 can be reduced as much as possible.

In addition, since the substrate 20 is fixed to both of the pair of flat plate portions 11, the substrate 20 can be firmly fixed to the housing 10.

(Embodiment 3)
Hereinafter, the third embodiment will be described in detail with reference to the drawings. In the following description, the same reference numerals will be used to designate the same parts as those in the first and second embodiments, and detailed description thereof will be omitted.

In this embodiment 3, the method of fixing the substrate 20 using the substrate fixture 30 and the configuration of the connecting member that electrically connects the first flat plate portion 11a and the substrate fixture 30 are different from those in the above-described embodiments 1 and 2.

Specifically, as in the first and second embodiments, the board fixture 30 is made of a screw, but in this third embodiment, one end of the board fixture 30 penetrates the second flat plate portion 11b from the second flat plate portion 11b side and enters the housing 10. One end of the board fixture 30 further penetrates the board 20 and is attached to the mounting fixture 50 provided between the board 20 and the first flat plate portion 11a. The hole in the board 20 through which the one end of the board fixture 30 passes is a screw hole, and one end of the board fixture 30 is fastened. The mounting fixture 50 also has a screw hole through which the one end of the board fixture 30 is fastened, and the part of the one end of the board fixture 30 that penetrates the board 20 is fastened to the mounting fixture 50. The mounting fixture 50 is made of a conductive material with as low an electrical resistivity as possible, and is preferably made of the same material as the board fixture 30. This does not prevent the mounting fixture 50 from being made of a conductive material different from the board fixture 30.

The connecting member is composed of a screw 340, as in the second embodiment. One end of the screw 340 penetrates the first flat plate portion 11a and is fastened to the mounting fixture 50. The connecting member is also composed of a screw 340. A screw hole is formed in the mounting fixture 50 to which one end of the screw 340 is fastened. The other end of the screw 340 is in contact with the first flat plate portion 11a and is electrically connected. Conductive grease may be provided between the screw 340 and the first flat plate portion 11a. The screw 340 is composed of a conductive material with as low an electrical resistivity as possible, and is preferably composed of the same material as the substrate fixing fixture 30. This does not prevent the screw 340 from being composed of a conductive material different from that of the substrate fixing fixture 30.

Even in the configuration of this embodiment 3, the board fixing device 30 arranged near the integrated circuit 21 and the first flat plate portion 11a are electrically connected by the screw 340 and the mounting fixture 50, so that the electromagnetic waves emitted from the housing 10 that houses the integrated circuit 21 can be reduced as much as possible.

In addition, since the substrate 20 is fixed to both of the pair of flat plate portions 11, the substrate 20 can be firmly fixed to the housing 10.

Other Embodiments
The technology disclosed herein is not limited to the above-described embodiment, and may be substituted without departing from the spirit and scope of the claims.

For example, in the above-mentioned embodiments 1 to 3, the first flat plate portion 11a and the board fixture 30 are electrically connected by the gasket 40 extending perpendicular to the surface of the first flat plate portion 11a and the screws 240 and 340. However, this is not limited to the above, and the first flat plate portion 11a and the board fixture 30 may be electrically connected by providing a conductive member extending laterally from the protrusion 12 toward the board fixture 30, for example.

In addition, in the above-described first to third embodiments, the first flat plate portion 11a and the board fixture 30 are electrically connected by columnar or axial members such as the gasket 40 and the screws 240 and 340. However, the first flat plate portion 11a and the board fixture 30 may be electrically connected by a linear member such as a harness or a plate-like member such as a copper plate.

The above-described embodiments are merely examples and should not be interpreted as limiting the scope of the present disclosure. The scope of the present disclosure is defined by the claims, and all modifications and variations that fall within the scope of equivalence of the claims are within the scope of the present disclosure.

The technology disclosed here is useful as a control unit structure for minimizing electromagnetic waves emitted from the housing.

1 Control unit 10 Housing 11 Flat plate portion 11a First flat plate portion (other flat plate portion)
11b Second flat plate portion (one flat plate portion)
20 Substrate 21 Integrated circuit 30 Substrate fixture 40 Gasket (connecting member)
50 Mounting tool 240 Screw (connecting member)
340 Screw (shaft-shaped member)

Claims (1)

A control unit structure, comprising:
a housing made of a conductive material and having at least a pair of flat plate portions facing each other;
a substrate on which an integrated circuit is mounted, the substrate being accommodated in the housing so as to be parallel to the flat plate portion;
a conductive substrate fixing member extending in a direction intersecting a direction in which the substrate extends and fixing the substrate to one of the flat plate portions;
the substrate fixing device is disposed in the vicinity of the integrated circuit when viewed from a direction perpendicular to a surface of the substrate,
The other flat plate portion and the substrate fixing tool are electrically connected to each other,
the board fixing tool is a screw, and one end of the board fixing tool penetrates one of the flat plate parts from one of the flat plate parts side through the one of the flat plate parts and the board, and is attached to a conductive mounting tool provided between the other of the flat plate parts and the board inside the housing,
A control unit structure characterized in that the substrate fixing device and the other flat plate portion are electrically connected by a conductive screw attached to the mounting device, with one end penetrating from the other flat plate portion side through the other flat plate portion .

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