JP2013207289A - Electronic apparatus - Google Patents

Abstract

An electronic apparatus capable of ground connection without exposing a ground layer on a surface of a circuit board.
An insulating layer that covers a ground layer is provided on a surface of a circuit board. The screw 50 is made of a conductive material, and has a protrusion 54 on the flange 52 of the screw head 51. The screw 50 passes through the through hole 14 formed in the circuit board 10 and is screwed into the screw hole 34 formed in the case body 30, so that the protrusion 54 is in contact with the ground layer 12. 10 is fixed to the case body 30.
[Selection] Figure 2

Description

  The present invention relates to an electronic device, and more particularly to an electronic device in which a circuit board on which an electronic component is mounted is accommodated in a case body.

  2. Description of the Related Art There is known an electronic apparatus including a circuit board on which electronic components are mounted, a case main body that accommodates the circuit board, and a cover that covers an opening of the case main body. Such an electronic device needs to perform ground connection in order to operate the electronic component.

  For example, Patent Document 1 discloses an electronic control device in which a cover formed of a conductive material is fixed to a case (case body) with screws through which through holes formed at four corners of a printed circuit board (circuit board) are inserted. (Electronic equipment) is described. In this device, conductive members (ground layers) are exposed at the four corner surfaces of the printed circuit board, and ground connection is performed by bringing the conductive members into contact with the lower surface of the cover by tightening screws.

JP-A-8-148842

  However, in the electronic control device described in Patent Document 1, it is necessary to expose the conductive member on the four corner surfaces of the printed circuit board in order to ensure a contact area between the conductive member and the cover.

  In view of the above, an object of the present invention is to provide an electronic device that can perform ground connection without exposing a ground layer to the surface of a circuit board.

  The present invention includes a circuit board on which an electronic component is mounted and an insulating layer covering a ground layer electrically connected to the electronic component is provided on the surface, and a case main body made of a conductive material and containing the circuit board And the circuit board is fixed to the case body with a screw made of a conductive material, and the screw is on the side of the circuit board on a flange portion that abuts the surface of the circuit board at the screw head. Protruding protrusions are provided, and the circuit board is fixed to the case body in a state where the protrusions are in contact with a ground layer of the circuit board.

  According to the present invention, by tightening the screw, the circuit board is fixed to the case main body, and the protruding portion of the screw penetrates the insulating layer of the circuit board and contacts the ground layer. Thereby, the ground layer is electrically connected to the case body via the screw.

  Therefore, the ground layer and the case body can be electrically connected by simply tightening the screw, and the ground connection can be performed without exposing the ground layer in advance as described in Patent Document 1. . Furthermore, if a ground layer is provided below the flange portion of the screw without securing an extra portion of the ground layer to be brought into contact with the cover or the case body as described in Patent Document 1, the ground connection can be performed. It becomes possible.

  The present invention includes a circuit board on which an electronic component is mounted and an insulating layer covering a ground layer electrically connected to the electronic component is provided on the surface, and a case main body made of a conductive material and containing the circuit board An electronic device in which the circuit board is fixed to the case body by a screw made of a conductive material, made of a conductive material, and disposed between a screw head of the screw and the circuit board, A washer having a protrusion protruding toward the circuit board on a contact surface with the circuit board, and the circuit board is fixed to the case body in a state where the protrusion is in contact with a ground layer of the circuit board. It is characterized by.

  According to the present invention, by tightening the screw, the circuit board is fixed to the case body, and the protrusion of the washer breaks through the insulating layer of the circuit board and contacts the ground layer. Thereby, the ground layer is electrically connected to the case body via the washer and the screw.

  Therefore, the ground layer and the case body can be electrically connected by simply tightening the screws. Therefore, if a ground layer is provided below the washer, ground connection can be performed.

  By the way, when the screw provided with the protrusion on the flange is tightened, the insulating layer and the ground layer of the circuit board are scraped by the protrusion and a face is generated. For this reason, there is a risk that the number of useless man-hours such as the work for removing the facet may increase.

  Therefore, in the present invention, the cover includes a cover that is mounted on the case main body and is disposed between the screw head and the circuit board, the protruding portion is in contact with the ground layer of the circuit board, and the protruding portion It is preferable that the circuit board and the cover are fixed to the case body in a state where a gap is provided between the cover and the cover.

  In this case, the facets are all accommodated in a space surrounded by the circuit board, the through hole of the cover, and the flange portion of the screw, and the facets are not scattered outside. Therefore, it is possible to reduce useless man-hours such as the work for removing the facets.

  When the washer is provided with a protrusion, the washer hardly rotates even when the screw is tightened, so that there is little possibility of generating facets. However, even in this case, it is preferable to provide a cover attached to the case, and the circuit board and the cover can be simultaneously fixed to the case body by tightening screws.

1 is a perspective view showing an electronic apparatus according to an embodiment of the present invention. II-II sectional view taken on the line of FIG. The corner top view of an electronic device. The perspective view of a case main body.

  An electronic apparatus according to an embodiment of the present invention will be described with reference to the drawings. As shown in FIG. 1, an electronic device 100 according to the present embodiment is an electronic control unit (ECU), for example, and includes a housing case 20 that is a housing that houses a circuit board 10 (see FIG. 2). Yes. The housing case 20 includes a case body 30 and a cover 40 that covers the opening of the case body 30. The circuit board 10 positioned and supported by the case body 30 is fastened together with the cover 40 by screws 50 and fixed to the case body 30.

  In the description of the present embodiment, for the sake of convenience, the direction along the front and back surfaces of the circuit board 10 accommodated in the case main body 30 will be described as the horizontal direction, and the direction orthogonal to the front and back surfaces of the circuit board 10 will be described as the vertical direction. However, the posture in which electronic device 100 is actually attached varies depending on the installation location.

  In addition to the connector 11, electronic components (not shown) are mounted on the circuit board 10 and a wiring pattern is formed. Examples of the electronic component include an IC chip, a transistor, a diode, and a capacitor. The electronic component is mounted on the front surface, the back surface, or the front and back surfaces of the circuit board 10.

  As shown in FIGS. 2 and 3, a ground layer 12 made of a material having excellent conductivity such as copper, which is electrically connected to an electronic component, is formed inside the circuit board 10. The front and back surfaces of the circuit board 10 are coated with an insulating layer 13 made of an insulator, and the surface of the ground layer 12 is covered with the insulating layer 13 and is not exposed. The insulating layer 13 is formed, for example, by applying a solder resist to the front and back surfaces of the circuit board 10.

  Further, the circuit board 10 has through holes 14 at four corners. And the ground layer 12 (two-dot chain line part of FIG. 3) is located in the vicinity of at least one through hole 14.

  As shown in FIG. 1, the case main body 30 and the cover 40 are made of a metal having heat conductivity, preferably a metal having high heat conductivity such as aluminum, copper, stainless steel, iron, and the like by pressing, cutting, welding. It is formed by using an appropriate processing method such as processing or die casting. The cover 40 is preferably formed by pressing a sheet metal.

  As shown in FIGS. 1 and 4, the case main body 30 includes a bottom wall 31 having a substantially rectangular shape (rectangular shape) in a plan view, and upward from each peripheral portion of the bottom wall 31 (in a direction toward the cover 40). It has a substantially rectangular parallelepiped box shape having an extended side wall 32 and opened upward as a whole. However, a cutout is formed in the side wall 32 of the case body 30 at a portion corresponding to the connector 11. Thereby, the connector 11 is exposed from the electronic device 100, and the connector 11 and an external harness (not shown) can be connected.

  A horizontal flange portion 33 is formed over the upper portion of each side wall 32, and the upper surface of the flange portion 33 serves as a substrate support surface for placing and supporting the circuit board 10. Screw holes 34 corresponding to the through holes 14 of the circuit board 10 are formed at the four corners of the flange portion 33. Further, a flange peripheral wall 35 rises upward from the outer peripheral end of the flange portion 33. The inner peripheral surface of the flange peripheral wall 35 is formed to be substantially the same as the outer surface of the cover 40, whereby the cover 40 is positioned by the flange peripheral wall 35.

  Further, the case main body 30 has a bulging portion 36 in which a through hole is formed in order to attach the electronic device 100 to another device (not shown) with a bolt or the like.

  As shown in FIG. 1, the cover 40 has a substantially quadrangular shape (rectangular shape) in plan view, and the four corners are recessed to form flange portions 41, and one through hole 42 is formed in each flange portion 41. Has been. These through holes 42 correspond to the screw holes 34 of the case body 30. Since the four corners of the cover 40 are recessed, and the screw head 51 of the screw 50 is positioned in the recessed flange portion 41, the screw head 51 does not protrude from the upper surface of the cover 40.

  As shown in FIGS. 2 and 3, the screw 50 is made of a conductive material, preferably a metal such as stainless steel or iron. The screw 50 has a screw head (bolt head) 51, and a flange portion 52 is integrally formed at a lower portion (screw tip direction) of the screw head 51.

  The lower surface of the flange portion 52 is provided with a screw shaft portion 53 in which an external thread is formed on the outer peripheral surface, and a projection portion 54 positioned outside the screw shaft portion 53. Here, a plurality of protrusions 54 are provided at equal intervals on the same circumference around the axis of the screw shaft portion 53. Each of the protrusions 54 protrudes downward and has a substantially conical shape.

  When the screw 50 is screwed into the screw hole 34, the projecting portion 54 breaks through the insulating layer 13 formed on the surface of the circuit board 10, and the projecting portion 54 so that the tip of the projecting portion 54 reaches at least the ground layer 12. The projecting height of the circuit board 10 exceeds at least the total thickness of the insulating layer 13 and the cover 40 of the circuit board 10.

  Hereinafter, a method for assembling the electronic device 100 will be described.

  First, the circuit board 10 and the cover 40 are temporarily supported on the case body 30. Specifically, the circuit board 10 is placed on the upper surface of the flange portion 33 of the case body 30, and the cover 40 is placed on the circuit board 10. At this time, the cover 40 is positioned by the flange peripheral wall 35 of the case body 30.

  Next, the screw 50 is inserted through the through hole 14 of the circuit board 10 and the through hole 42 of the cover 40 and is screwed into the screw hole 34 of the case body 30. Here, the diameter of the through hole 14 of the circuit board 10 is formed so as to be larger than the outer diameter of the screw shaft portion 53 of the screw 50 and smaller than the diameter of the circumference where the protrusions 54 are continuous. On the other hand, the diameter of the through hole 42 of the cover 40 is formed so as to be larger than the diameter of the circumference where the protrusions 54 are continuous and smaller than the diameter of the flange portion 52 of the screw 50.

  Therefore, by tightening the screw 50, the circuit board 10 and the cover 40 are fixed to a predetermined position of the case main body 30, and the protrusion 54 of the screw 50 breaks through the insulating layer 13 of the circuit board 10 and the ground layer 12. I bite into and touch. Thereby, the ground layer 12 is electrically connected to the case body 30 and the cover 40 via the screw 50.

  As described above, the ground layer 12 can be electrically connected to the case body 30 and the cover 40 simply by tightening the screw 50, and the ground layer is exposed in advance as described in Patent Document 1. In addition, a ground connection can be made. Further, as described in Patent Document 1, it is possible to connect the ground by simply providing the ground layer 12 below the flange portion 52 of the screw 50 without securing an extra portion of the ground layer to be brought into contact with the cover or the case body. Can be performed. And since the projection part 54 of the screw 50 bites into the circuit board 10, the screw 50 is hard to loosen.

  By the way, when the screw 50 is tightened, the insulating layer 13 and the ground layer 12 of the circuit board 10 are scraped by the protrusions 54 to generate facets. However, the facets are all accommodated in a space S surrounded by the upper surface of the circuit board 10, the inner peripheral surface of the through hole 42 of the cover 40, and the lower surface of the flange portion 52 of the screw 50. Since the space S becomes a face receiving portion and the face does not scatter to the outside, it is possible to reduce useless man-hours such as face removal work.

  In the present embodiment, the ground layer 12 (two-dot chain line portion in FIG. 3) is formed in a part of the circuit board 10 in the vicinity of the periphery of the through hole 14. Therefore, multiple (8) protrusions 54 are provided on the screw 50 so that the ground layer 12 and the protrusions 54 are in contact with each other. However, when the ground layer 12 is formed over the entire periphery of the circuit board 10 in the vicinity of the through hole 14, the number of the protrusions 54 of the screw 50 may be one.

  As mentioned above, although embodiment of this invention was described with reference to drawings, this invention is not limited to this. For example, the case where the protrusion part 54 was provided in the lower surface of the flange part 52 integral with the screw head 51 of the screw 50 was demonstrated. However, the protrusion may be provided on a washer that is separate from the screw and is disposed between the screw head of the screw and the circuit board 10 and made of a conductive material.

  Also in this case, as in the embodiment of the present invention, the circuit board 10 and the cover 40 are fixed at predetermined positions of the case body 30 by tightening the screws, and the protrusion of the washer is insulated from the circuit board 10. Break through layer 13 and bite into contact with ground layer 12. Thereby, the ground layer 12 is electrically connected to the case body 30 and the cover 40 via the washer and the screw.

  Therefore, the ground layer 12, the case body 30, and the cover 40 can be electrically connected by simply tightening the screws. The ground connection can be made only by providing the ground layer 12 below the washer. And since a washer is used, a screw is hard to loosen.

  Furthermore, even if the screw is tightened, the washer hardly rotates, so that there is little possibility that the insulating layer 13 and the ground layer 12 of the circuit board 10 are scraped by the protrusions and a face is generated. Therefore, since it is not necessary to provide the facet accommodating part, it is not necessary to have the cover 40 in order to provide the facet accommodating part.

  DESCRIPTION OF SYMBOLS 10 ... Circuit board 11 ... Connector (electronic component) 12 ... Ground layer 13 ... Insulating layer 14 ... Through-hole 20 ... Housing case 30 ... Case main body 31 ... Bottom wall 32 ... Side wall 33 ... Flange 34 ... Screw hole, 35 ... Flange peripheral wall, 40 ... Cover, 41 ... Flange part, 42 ... Through hole, 50 ... Screw, 51 ... Screw head, 52 ... Flange part, 53 ... Screw shaft part, 54 ... Projection Part, 100 ... electronic equipment.

Claims (3)

A circuit board on which an electronic component is mounted and an insulating layer covering a ground layer electrically connected to the electronic component is provided on the surface;
A case body made of a conductive material and containing the circuit board,
An electronic device in which the circuit board is fixed to the case body with a screw made of a conductive material,
The screw includes a protrusion that protrudes toward the circuit board on a flange portion that contacts the surface of the circuit board at a screw head,
An electronic apparatus, wherein the circuit board is fixed to the case body in a state in which the protrusion is in contact with a ground layer of the circuit board. A circuit board on which an electronic component is mounted and an insulating layer covering a ground layer electrically connected to the electronic component is provided on the surface;
A case body made of a conductive material and containing the circuit board,
An electronic device in which the circuit board is fixed to the case body with a screw made of a conductive material,
A washer made of a conductive material, disposed between a screw head of the screw and the circuit board, and provided with a washer having a protrusion protruding toward the circuit board on a contact surface with the circuit board;
An electronic apparatus, wherein the circuit board is fixed to the case body in a state in which the protrusion is in contact with a ground layer of the circuit board. A cover mounted on the case body and disposed between the screw head and the circuit board;
The circuit board and the cover are fixed to the case body in a state in which the protrusion is in contact with the ground layer of the circuit board and a gap is provided between the protrusion and the cover. The electronic device according to claim 1 or 2.

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