JP2023127764A - Electronic control device - Google Patents

Abstract

The present invention provides an electronic control device that can reduce electromagnetic radiation while suppressing deformation of a circuit board that occurs when a conductive member is pressed by a circuit board.
[Solution] A first conductive case and a circuit board are electrically connected via a first conductive member, and a second conductive case and the circuit board are electrically connected via a second conductive member. be done. The first conductive member is arranged at a higher position than the board mounting surface of the first conductive casing. The circuit board is fixed to the first casing while pressing the first conductive member. The second conductive member presses the circuit board by contacting the circuit board on the opposite side of the first conductive member.
[Selection diagram] Figure 1

Description

The present invention relates to an electronic control device mounted on an automobile. The present invention relates to electronic control devices such as engine control units, automatic transmission control units, advanced driving support systems, and automatic driving control units.

In recent years, demand for advanced driver assistance systems (hereinafter referred to as "ADAS") and automatic driving (hereinafter referred to as "AD") systems has increased, and the development of automatic driving technology for automobiles is accelerating. Semiconductor components such as CPUs with high operating frequencies, which are installed in electronic control devices for ADAS or AD, are one of the sources of electromagnetic radiation. As an example of measures to reduce electromagnetic radiation radiated into the external environment, a circuit board assembly has a configuration in which a circuit board and a metal casing that protects the circuit board are electrically connected via a conductive gasket. known (see Patent Document 1).

Japanese Patent Application Publication No. 2000-312091

When realizing the electrical connection between the circuit board and the metal casing as described above through a conductive member such as a conductive gasket, it is conceivable to press the conductive member with the circuit board.
However, when a conductive member is pressed by a circuit board, the circuit board is deformed and large distortion occurs in the electronic components mounted on the circuit board. As a result, it may become impossible to ensure electrical connection between the electronic component and the circuit board, and in some cases, the electronic component may be damaged.

An object of the present invention is to provide an electronic control device that can reduce electromagnetic radiation while suppressing deformation of a circuit board that occurs when pressing a conductive member with a circuit board.

In order to solve the above problems, for example, the configurations described in the claims are adopted.
The present application includes a plurality of means for solving the above-mentioned problems, but to name one, it is composed of a circuit board on which electronic components are mounted, a first casing, and a second casing, and the circuit board is It is placed on the opposing surface of the protective housing and the circuit board in the first housing, and is interposed between the first housing and the circuit board to electrically connect the circuit board and the first housing. and a second conductive member that is disposed on a surface of the second housing facing the circuit board and electrically connects the second housing and the circuit board. The first conductive member is disposed at a higher position than the board mounting surface of the first casing, the circuit board is fixed to the first casing while pressing the first conductive member, and the second conductive member The circuit board is pressed by contacting the circuit board on the side opposite to the conductive member.

According to the present invention, electromagnetic radiation can be reduced while suppressing deformation of the circuit board that occurs when pressing a conductive member with the circuit board.

1 is a sectional view showing the structure of an electronic control device according to a first embodiment of the present invention. FIG. 3 is a cross-sectional view showing the structure of an electronic control device according to a second embodiment of the present invention. FIG. 3 is a cross-sectional view showing the structure of an electronic control device according to a third embodiment of the present invention. It is a sectional view showing the structure of an electronic control device concerning a fourth embodiment of the present invention.

Embodiments of the present invention will be described in detail below with reference to the drawings. In this specification and the drawings, elements having substantially the same functions or configurations are designated by the same reference numerals, and redundant description will be omitted.

[First embodiment]
FIG. 1 is a sectional view showing the structure of an electronic control device according to a first embodiment of the present invention.
As shown in FIG. 1, the electronic control device according to the first embodiment includes a first conductive case 1, a second conductive case 2, a circuit board 3, a first conductive member 50, and a second conductive case 1. A conductive member 51 is provided. The first conductive case 1 corresponds to a first case, and the second conductive case 2 corresponds to a second case. The first conductive case 1 and the second conductive case 2 constitute a case that protects the circuit board 3. The circuit board 3 is a rigid board, such as a printed wiring board on which a wiring pattern is formed on one or both sides.

A semiconductor component 4 is mounted on the circuit board 3. The semiconductor component 4 is, for example, an electronic component having a package structure in which a semiconductor chip such as a CPU with a high operating frequency mounted in an electronic control device for ADAS or AD is sealed with resin or the like. The electronic components mounted on the circuit board 3 also include electronic components (not shown) other than the semiconductor component 4.

The first conductive case 1 and the second conductive case 2 are each conductive cases. There are various forms of conductive casings, such as metal casings made of metal materials, conductive resin casings made of conductive resin materials, and resin casings with metal members inserted. Conceivable. By constructing the first conductive housing 1 and the second conductive housing 2 from a metal material or a conductive resin material, respectively, it is possible to impart an electromagnetic shielding function to the housing.

The first conductive case 1 and the circuit board 3 are electrically connected via the first conductive member 50. The electrical connection state between the first conductive case 1 and the circuit board 3 is achieved by sandwiching the first conductive member 50 between the first conductive case 1 and the circuit board 3. This can be obtained by contacting both the first conductive casing 1 and the circuit board 3.

On the other hand, the second conductive casing 2 and the circuit board 3 are electrically connected via the second conductive member 51. The electrical connection state between the second conductive case 2 and the circuit board 3 is achieved by sandwiching the second conductive member 51 between the first conductive case 2 and the circuit board 3. This can be obtained by contacting both the first conductive casing 2 and the circuit board 3.

In this way, the first conductive case 1 and the circuit board 3 are electrically connected via the first conductive member 50, and the second conductive case 2 and the circuit board 3 are connected by the second conductive member 51. By electrically connecting the semiconductor components 4 and the like through the electrical connection, it is possible to reduce electromagnetic radiation emitted to the external environment from the semiconductor component 4 and the like as a source.

The first conductive case 1 and the second conductive case 2 protect the circuit board 3, the semiconductor component 4, the first conductive member 50, the second conductive member 51, a connector (not shown), etc. from the external environment. There is. The connector is a component mounted on the circuit board 3 in a state where it is electrically connected to a wiring pattern (not shown) on the circuit board 3.

The first conductive housing 1 has a plurality of board mounting surfaces 10. The board mounting surface 10 is formed on the first conductive housing 1 in order to mount the circuit board 3 on the first conductive housing 1 . The plurality of board mounting surfaces 10 are formed, for example, to be located at the four corners of the circuit board 3.

The circuit board 3 is placed on the board mounting surface 10, and in this state is fixed to the first conductive casing 1 using, for example, screws (not shown). In that case, the circuit board 3 is provided with a through hole for inserting a screw, and the first conductive casing 1 is provided with a screw hole that engages with the screw.

The first conductive member 50 is a surface of the first conductive casing 1 (the top surface in FIG. 1), and a surface where the first conductive casing 1 and the circuit board 3 face each other (the surface with which the circuit board 3 faces). located on the opposite side). The upper surface of the first conductive member 50 is arranged at a higher position than the board mounting surface 10 of the first conductive housing 1 . That is, a portion of the first conductive member 50 is arranged to protrude beyond the board mounting surface 10. In other words, the first conductive member 50 is arranged so as to be pressed by the circuit board 3 when the circuit board 3 is mounted and fixed on the board mounting surface 10 .

The second conductive member 51 is one surface (lower surface in FIG. 1) of the second conductive case 2, and the surface where the second conductive case 2 and the circuit board 3 face each other (the surface opposite to the circuit board 3). located on the opposite side). The second conductive member 51 is in contact with the second conductive housing 2 in advance, for example, by applying a conductive material to the second conductive housing 2 to form the second conductive member 51 . The second conductive member 51 is placed at the position of the second conductive housing 2 . In the left-right direction in FIG. 1, the dimensions of the second conductive member 51 are smaller than the dimensions of the first conductive member 50. Further, in the left-right direction in FIG. 1, the second conductive member 51 is disposed at or near the center of the first conductive member 50. The second conductive member 51 is arranged at a position where it presses the circuit board 3 when fixing the second conductive case 2 to the first conductive case 1. In other words, the second conductive member 51 presses the circuit board 3 so as to reduce deformation of the circuit board 3 caused by pressing the first conductive member 50 . This leads to suppression of deformation of the circuit board 3 and, in turn, to a reduction in the amount of distortion occurring in electronic components such as the semiconductor components 4 mounted on the circuit board 3.

The first conductive member 50 and the second conductive member 51 may be formed of a shield adhesive, a conductive gasket, or the like. Further, as the shielding adhesive, a cured in place gasket that adheres to only one side can be considered. Furthermore, as the base material for the constituent materials of the first conductive member 50 and the second conductive member 51, various materials such as silicone, epoxy, acrylic, etc. can be selected depending on the environment in which the electronic control device is installed. . Furthermore, various materials can be selected as the conductive filler contained in the first conductive member 50 and the second conductive member 51, such as silver, copper, aluminum, nickel, and graphite. Further, the conductive filler may be subjected to surface treatment such as nickel plating or copper plating. Further, the first conductive member 50 and the second conductive member 51 may be made of different materials or the same material.

In the electronic control device according to the first embodiment described above, the circuit board 3 is placed on the board mounting surface 10 of the first conductive case 1, and the circuit board 3 is attached to the first conductive case 1 using screws (not shown) or the like. 1, the circuit board 3 is fixed by receiving a downward force in FIG. Therefore, the direction in which the circuit board 3 is fixed is downward in FIG. Further, the circuit board 3 receives a downward force in FIG. 1 and presses the first conductive member 50. At this time, the first conductive member 50 is compressed and deformed by being pressed by the circuit board 3, and a reaction force due to this compressive deformation is applied to the circuit board 3. Therefore, the circuit board 3 is warped in a direction opposite to the fixing direction, that is, in an upward direction. Although the warpage of the circuit board 3 is extremely small and does not pose a problem during the manufacturing (assembly) stage of the electronic control device, as the electronic control device is used for a long period of time, it becomes affected by the installation environment (e.g. temperature and humidity). There is a risk that it will gradually become larger.

On the other hand, when fixing the second conductive case 2 to the first conductive case 1, the second conductive member 51 presses the circuit board 3 from the side opposite to the first conductive member 50. At this time, the second conductive member 51 is compressed and deformed by being sandwiched between the second conductive casing 2 and the circuit board 3 , and a reaction force due to this compressive deformation is applied to the circuit board 3 . Further, the second conductive member 51 presses the circuit board 3 downward in FIG. 1, which is the direction in which the warp is reversed in the direction in which the circuit board 3 is warped by the pressure of the first conductive member 50. Thereby, deformation of the circuit board 3 can be suppressed. Therefore, electromagnetic radiation can be reduced while suppressing deformation of the circuit board 3 that occurs when the circuit board 3 presses the conductive member.

[Second embodiment]
FIG. 2 is a sectional view showing the structure of an electronic control device according to a second embodiment of the present invention.
As shown in FIG. 1, the first conductive case 1 and the second conductive case 2 form a first conductive contact P1 outside the first conductive member 50. The first conductive contact P1 is a conductive contact that electrically connects the first conductive case 1 and the second conductive case 2.

On the other hand, the second conductive member 51 is arranged in a part of the second conductive housing 2 as described above. The second conductive member 51 forms a second conductive contact P2 by contacting the circuit board 3. The second conductive contact P2 is a conductive contact that electrically connects the second conductive member 51 and the circuit board 3.

The distance between the first conductive contact P1 and the second conductive contact P2 is less than or equal to half a wavelength of the frequency of electromagnetic radiation generated from the circuit board 3 and/or the semiconductor component 4. Thereby, electromagnetic radiation leaking to the outside of the electronic control device can be effectively reduced.

The method of fixing the circuit board 3 to the first conductive housing 1 is not limited to the fixing method using screws, and various methods can be considered. For example, as fixing devices other than screws, although not shown, there are various fixing methods such as fixing by pressing through a rubber material, fixing by press fit, fixing by sandwiching between the first conductive casing 1 and the second conductive casing 2, etc. You can choose the method.

[Third embodiment]
FIG. 3 is a sectional view showing the structure of an electronic control device according to a third embodiment of the present invention.
As shown in FIG. 3, a portion of the first conductive member 50 has a convex shape 52. As shown in FIG. The convex shape 52 is formed on one surface (the upper surface in FIG. 3) of the first conductive member 50 and on the surface facing the circuit board 3. The convex shape 52 is formed in a portion of the first conductive member 50 before being pressed, and is formed in a state of protruding toward the second conductive housing 2 side. Therefore, the thickness of the first conductive member 50 is greater in the portion where the convex shape 52 is formed than in the other portions. Further, the convex shape 52 is arranged at a position facing the second conductive member 51 with the circuit board 3 interposed therebetween.

In such a configuration, when pressing the first conductive member 50 with the circuit board 3, the convex shape 52 of the first conductive member 50 comes into contact with the circuit board 3 before other parts, and in that state, the first conductive member 50 contacts the circuit board 3. One conductive member 50 is pressed by the circuit board 3 . Therefore, when the circuit board 3 is in contact with the board mounting surface 10 of the first conductive housing 1, the portion where the convex shape 52 is formed is pressed with a stronger force than other portions and compressively deforms. Therefore, in the first conductive member 50, the portion where the convex shape 52 is formed locally becomes a highly compressed region. By providing a highly compressed region in the first conductive member 50 by the convex shape 52 in this way, the distance between the conductive fillers contained in the first conductive member 50 is relatively narrowed, and the impedance is reduced. Therefore, electromagnetic radiation emitted to the outside of the electronic control device can be further reduced.

[Fourth embodiment]
FIG. 4 is a sectional view showing the structure of an electronic control device according to a fourth embodiment of the present invention.
As shown in FIG. 4, the second conductive case 2 and the circuit board 3 are fixed together to the first conductive case 1. Specifically, through holes are formed in the second conductive housing 2 and the circuit board 3 so as to have the same positional relationship as the screw holes formed in the board mounting surface 10 of the first conductive housing 1, A screw 5 is passed through this through hole, and the screw 5 is engaged with the screw hole. Then, by tightening the screws 5 with a predetermined torque, the second conductive housing 2 and the circuit board 3 are jointly fixed to the first conductive housing 1. Thereby, the second conductive housing 2 and the circuit board 3 can be attached to the first conductive housing 1 at the same time. Therefore, the number of man-hours required for assembling the electronic control device can be reduced.

The first conductive member 50 is disposed on one surface of the first conductive casing 1 (the surface facing the circuit board 3) higher than the board mounting surface 10, similarly to the embodiment described above. In other words, the first conductive member 50 is arranged so as to be pressed by the circuit board 3 when the circuit board 3 is mounted on the board mounting surface 10 and fixed by tightening the screws 5 . When the first conductive member 50 is pressed, the circuit board 3 deforms in the direction of the second conductive member 51 in response to a reaction force due to compressive deformation of the first conductive member 50 . On the other hand, the second conductive member 51 is sandwiched between the second conductive casing 2 and the circuit board 3. Further, the second conductive member 51 is arranged at a position to suppress deformation of the circuit board 3 when the first conductive member 50 is pressed.

The second conductive member 51 has a smaller volume than the first conductive member 50. For the same compressibility, the smaller the volume, the greater the compressive stress. Therefore, by arranging the first conductive member 50 and the second conductive member 51 so that the compressibility of the conductive member with a small volume is smaller than that of the conductive member with a large volume, the compressive stress can be balanced. can also be considered.

Note that the present invention is not limited to the above-described embodiments, and includes various modifications. For example, the embodiments described above are described in detail to explain the present invention in an easy-to-understand manner, and the present invention is not necessarily limited to having all the configurations described. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment, and it is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to add, delete, or replace some of the configurations of other embodiments.

DESCRIPTION OF SYMBOLS 1...First conductive housing, 2...Second conductive housing, 3...Circuit board, 4...Semiconductor component (electronic component), 10...Board mounting surface, 50...First conductive member, 51...Second conductive Member, 52...convex shape

Claims (9)

A circuit board equipped with electronic components,
a casing configured by a first casing and a second casing and protects the circuit board;
The circuit board is disposed on a surface of the first casing facing the circuit board, and is interposed between the first casing and the circuit board to electrically connect the circuit board and the first casing. a first conductive member,
a second conductive member disposed on a surface of the second casing facing the circuit board and electrically connecting the second casing and the circuit board;
The first conductive member is arranged at a higher position than the board mounting surface of the first casing,
The circuit board is fixed to the first casing while pressing the first conductive member,
The second conductive member is an electronic control device that presses the circuit board by contacting the circuit board on a side opposite to the first conductive member. The electronic control device according to claim 1,
The first casing and the second casing are electronic control devices made of a metal material or a conductive resin material. The electronic control device according to claim 1 or 2,
The first electrically conductive member and the second electrically conductive member are electrically conductive gaskets. The electronic control device according to claim 1 or 2,
The first electrically conductive member and the second electrically conductive member are shield adhesives. The electronic control device according to claim 4,
The shielding adhesive is CIPG (Cured In Placed Gasket). The electronic control device according to any one of claims 1 to 5,
When the circuit board is warped in a direction opposite to the direction in which the circuit board is fixed, the second conductive member is pressed in a direction to unwarp the circuit board, with respect to a direction in which the circuit board is warped. The electronic control device according to any one of claims 1 to 6,
The first housing and the second housing form a first conductive contact outside the first conductive member,
The second conductive member is disposed in a part of the second casing and forms a second conductive contact by contacting the circuit board,
In the electronic control device, the distance between the first conductive contact and the second conductive contact is equal to or less than a half wavelength of the frequency of electromagnetic radiation generated from the circuit board and/or the electronic component. The electronic control device according to any one of claims 1 to 7,
An electronic control device in which a portion of the first conductive member has a convex shape. The electronic control device according to any one of claims 1 to 8,
The second casing and the circuit board are both fixed to the first casing by fastening.

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