Electronic control unit

Abstract

To provide an electronic control device that is easy to manage the compression force acting on a conductive member electrically connecting a circuit board and a housing, even when the housing is surface treated.SOLUTION: The electronic control device has a circuit board 2 on which electronic components 5 are mounted, a conductive member 3 mounted on the circuit board 2, a metal housing 4 that houses the circuit board 2 and has a thin-film insulation treatment applied to the metal substrate, a mounting surface 7g on which the circuit board 2 is mounted on the metal housing 4, and a contact surface 7h on which the conductive member 3 contacts on the metal housing 4, where the metal substrate is exposed on the mounting surface 7g and contact surface 7h.SELECTED DRAWING: Figure 2

Description

Technical Field

[0001] The present invention relates to an electronic control device.

Background Art

[0002] In an electronic control device used in a vehicle or the like, electromagnetic waves (noise) radiated from electronic components such as a CPU mounted on a circuit board have been a problem. For example, in Patent Document 1, in order to reduce electromagnetic waves, a plurality of connection portions connecting the front and back surfaces of a wiring board (circuit board) on which electronic components are mounted and a housing are provided, and a shielding structure of the housing sandwiching the wiring board by the connection portions is disclosed.

[0003] Further, in an electronic control device, the electronic components mounted on the circuit board include heat generating elements, and the heat generated from these heat generating elements has also been a problem. For example, in Patent Document 2, in order to promote heat transfer from a heat generating element to a housing, an electronic control device in which a surface treatment (for example, application or electrodeposition of an insulating material, anodizing treatment, etc.) for promoting heat absorption and radiation is applied to at least one of the inner and outer surfaces of the housing is disclosed.

Prior Art Documents

Patent Documents

[0004]

Patent Document 1

Patent Document 2

Summary of the Invention

Problems to be Solved by the Invention

[0005] In Patent Document 1, since the circuit board is fixed to the housing only with screws at the connection part, there is a possibility that large distortion may occur in the circuit board, and it becomes impossible to mount electronic components on the part where the screws are attached on the circuit board. As a method of improving these points, it is conceivable to reduce the number of screws by inserting a conductive member between the board and the housing and electrically connecting the board and the housing with the conductive member. However, in this method, it is important to manage the compressive force acting on the conductive member (the amount of compression of the conductive member). That is, for example, if the compressive force acting on the conductive member is insufficient due to variations in the dimensions and surface shape of each component, etc., the contact electrical resistance of the conductive material increases, and there is a possibility that the electrical connection between the board and the housing is insufficient and noise cannot be sufficiently reduced. Particularly when the housing is surface-treated as in Patent Document 2, since differences are likely to occur in the thickness of the film formed by the surface treatment and the flatness of the housing surface, the management of the compressive force acting on the conductive member can become even more difficult.

[0006] An object of the present invention is to provide an electronic control device in which, even when the housing is surface-treated, it is easy to manage the compressive force acting on the conductive member that electrically connects the circuit board and the housing.

Means for Solving the Problems

[0007] In order to achieve the above object, the electronic control device of the present invention includes a circuit board on which electronic components are mounted, a conductive member mounted on the circuit board, a metal housing that houses the circuit board and has a thin film insulation treatment applied to a metal substrate, a mounting surface on the metal housing on which the circuit board is mounted, and a contact surface on the metal housing where the conductive member contacts, and it is assumed that the metal substrate is exposed at the mounting surface and the contact surface.

Effects of the Invention

[0008] According to the present invention, since it becomes easy to manage the compressive force acting on the conductive member, electromagnetic waves radiated from the electronic control device can be reduced. Problems, configurations, and effects other than those described above will be clarified by the description of the following embodiments.

Brief Description of the Drawings

[0009]

Figure 1

Figure 2

Figure 3

Figure 4

Figure 5

Embodiments for Carrying Out the Invention

[0010] In order to achieve the above object, the electronic control device of the present invention includes a circuit board on which electronic components are mounted, a plurality of conductive members mounted on the circuit board, a metal housing that houses the circuit board and is subjected to a thin-film insulation treatment on a metal base, a mounting surface on the metal housing on which the circuit board is mounted, and a plurality of contact surfaces on the metal housing where the plurality of conductive members come into contact. The metal base is exposed on the mounting surface and the plurality of contact surfaces, and the plurality of contact surfaces are located below the mounting surface. The plurality of conductive members are arranged along a first direction, and the mounting surface is disposed opposite to the plurality of conductive members with a space therebetween in a second direction orthogonal to the first direction. In order to make the values of the contact electrical resistances generated in each of the plurality of conductive members closer to each other, the distances in the height direction of each of the mounting surface and the plurality of contact surfaces are made uniform.

[0011] (First Embodiment) FIG. 2 is a sectional view taken along line A-A shown in FIG. 1 of the electronic control device 1 according to the first embodiment of the present invention. The electronic control device 1 includes a circuit board 2, a conductive member 3, and a metal housing 4.

[0012] The circuit board 2 is a board having printed wiring (not shown), and a plurality of electronic components 5 are mounted thereon. Further, a connector 6 for connecting to a ground circuit (not shown) is provided on the circuit board 2 so as to be connected to the printed wiring.

[0013] The conductive member 3 is a substance with high electrical conductivity mounted on the circuit board 2 to release the electromagnetic radiation generated on the circuit board 2 to the metal housing 4. The conductive member 3 is electrically connected to the circuit ground portion (not shown) of the circuit board 2. As the conductive member 3, for example, a component having conductivity that can be mounted on the circuit board 2 by soldering or the like (for example, chip resistor, ceramic capacitor, etc.), or a material containing a conductive filler (silver filler, copper filler, or graphite filler treated with metal plating, etc.) in a silicone adhesive can be used. The contact electrical resistance of the conductive member 3 can change depending on the magnitude of the compressive force acting from the outside. The conductive member 3 of the present embodiment is in contact with the contact surface 7h while receiving a predetermined compressive force from the contact surface 7h (described later).

[0014] The metal housing 4 is a housing that houses the circuit board 2 and has a thin film insulation treatment applied to the metal substrate. The metal housing 4 includes a base portion 7 on which the circuit board 2 is placed, and a cover portion 8 attached to the upper portion of the base portion 7 to cover the circuit board 2.

[0015] When a thin film insulation treatment is applied to the metal housing 4, electromagnetic waves are easily radiated as thermal energy from the surface of the metal housing 4, the surface emissivity of the metal housing 4 is improved, and the heat generated from the electronic component 5 mounted on the circuit board 2 can be efficiently released to the outside of the metal housing 4. Note that, from the viewpoint of reducing manufacturing costs, anodizing treatment is preferable for the thin film insulation treatment. Note that the film thickness of the anodizing treatment can vary depending on the treatment time. If the film thickness of the anodizing treatment is excessively thin, sufficient surface emissivity cannot be ensured. On the other hand, if the film thickness of the anodizing treatment is excessively thick, heat conduction decreases. Therefore, the treatment time of the anodizing treatment is set to a predetermined time so that the film thickness of the anodizing treatment on the surface of the metal housing 4 becomes an appropriate film thickness.

[0016] The base portion 7 includes a recess 7a in which the circuit board 2 is housed. Fins 7b for cooling are provided on the bottom surface of the base portion 7, and bolt holes 7c (see FIG. 1) used for fixing to, for example, a vehicle or the like are provided on the side surface of the base portion 7. Further, the base portion 7 can be formed by casting, for example, an aluminum alloy.

[0017] In the recessed portion 7a, a first protrusion 7e and a second protrusion 7f that protrude upward (+Y direction) from the lower surface 7d are provided.

[0018] The first protrusion 7e is a protrusion having at its upper end a mounting surface 7g on which the circuit board 2 is mounted. On the mounting surface 7g, the metal substrate of the metal housing 4 is exposed (hereinafter, the portion of the metal housing 4 where the metal substrate is exposed may be referred to as the "substrate portion"). When the circuit board 2 is placed on this mounting surface 7g, the circuit board 2 and the base portion 7 (metal housing 4) are electrically connected. Note that the mounting surface 7g may expose the metal substrate at least in the portion where the circuit board 2 is mounted, or may expose the metal substrate over the entire surface. The mounting surface 7g may be provided with screw holes (not shown) for screwing the screws 9 for fixing the circuit board 2 to the base portion 7.

[0019] The second protrusion 7f is a protrusion having at its upper end a contact surface 7h with which the conductive member 3 comes into contact. On the contact surface 7h, the metal substrate of the metal housing 4 is exposed. Since the conductive member 3 is brought into contact with this contact surface 7h, the circuit ground portion of the circuit board 2 and the base portion 7 (metal housing 4) are electrically connected via the conductive member 3. Note that the contact surface 7h may expose the metal substrate at least in the portion where the conductive member 3 comes into contact, or may expose the metal substrate over the entire surface.

[0020] As a result of the circuit board 2 being electrically connected to the metal housing 4 at two points, namely the mounting surface 7g and the contact surface 7h, as described above, the circuit board 2 and the metal housing 4 are connected at the same potential (GND).

[0021] In order to expose the metal substrate on the mounting surface 7g and the contact surface 7h, for example, masking processing on the mounting surface 7g and the contact surface 7h before the thin-film insulation processing, or cutting processing (for example, milling) on the mounting surface 7g and the contact surface 7h covered with the insulating thin film after the thin-film insulation processing may be performed.

[0022] The conductive members 3 can be arranged at a predetermined interval in the front-rear direction (Z-axis direction) of the electronic control device 1. In this case (that is, when a plurality of conductive members 3 are arranged), it is preferable to set the mounting surface 7g at a position facing each conductive member 3 in the left-right direction (X-axis direction) of the electronic control device 1. Note that the second protrusions 7f (contact surfaces 7h) may be provided according to the number of the conductive members 3, or a plurality of conductive members 3 may be placed on one second protrusion 7f (contact surface 7h). The same applies to the mounting surface 7g.

[0023] The contact surface 7h is located below the mounting surface 7g. The distance in the height direction between the contact surface 7h and the mounting surface 7g (the height difference between the contact surface 7h and the mounting surface 7g) affects the compression force exerted on the circuit board 2 in contact with the conductive member 3 by the contact surface 7h, and thus affects the contact electrical resistance generated by the conductive member 3. Therefore, the distance in the height direction between the contact surface 7h and the mounting surface 7g is determined based on the value of the contact electrical resistance that the conductive member 3 should generate. By the way, when a plurality of conductive members 3 are arranged as described above, it is preferable to align the height of the contact surface 7h in contact with each conductive member 3 and the height of each mounting surface 7g corresponding to each contact surface 7h. That is, it is preferable to make the variation in the distance in the height direction between the mounting surface 7g and the contact surface 7h fall within a predetermined range.

[0024] The bolt hole 7c (see FIG. 1) is a screw hole for fixing the electronic control device 1 to, for example, a vehicle body with a bolt (not shown). The base portion 7 is grounded by assembling a bolt into the bolt hole 7c and fixing it to the vehicle body.

[0025] The cover portion 8 is a component attached to the upper part of the base portion 7 and covering the circuit board 2, and is fixed to the base portion 7 by a fixture such as a screw 10. For example, an aluminum plate can be used as the cover portion 8.

[0026] The circuit board 2 is mounted on the mounting surface 7g of the base portion 7 and fixed to the base portion 7 with screws 9. The conductive member 3 mounted on the circuit board 2 is pressed against the contact surface 7h where the metal substrate is exposed, electrically connecting the circuit GND portion of the circuit board 2 and the base portion 7 (metal housing 4).

[0027] In addition, in this embodiment, an embodiment in which the circuit board 2 is fixed to the base portion 7 with screws 9 is shown. However, it is not limited to this, and the circuit board 2 may be fixed to the base portion 7 by other methods, for example, an adhesive or a resin fixture.

[0028] Also, in this embodiment, an embodiment in which the circuit board 2 is connected to the ground line via the connector 6 and the base portion 7 of the metal housing 4 is grounded via the vehicle body is shown. However, it is not limited to this, and either one of the circuit board 2 and the metal housing 4 may be grounded.

[0029] [Effect] In the electronic control device 1 of this embodiment, the metal substrate of the metal housing 4 is exposed at the mounting surface 7g on which the circuit board 2 is mounted and the contact surface 7h with which the conductive member 3 contacts on the metal housing 4, and the circuit board 2 is electrically connected to the metal housing 4 at two points, the mounting surface 7g and the contact surface 7h. Moreover, the compressive force acting on the conductive member 3 can be managed by the distance in the height direction between the contact surface 7h and the mounting surface 7g, and the distance can be managed with relatively high accuracy during the manufacture of the metal housing 4. That is, according to this embodiment, even when the surface treatment is performed on the metal housing 4, it becomes easy to manage the compressive force acting on the conductive member 3, and the electromagnetic waves (noise) radiated from the electronic control device 1 can be reduced.

[0030] Also, in this embodiment, the distance in the height direction between the contact surface 7h and the mounting surface 7g is determined based on the value of the contact electrical resistance that the conductive member 3 should generate. Thereby, the contact electrical resistance generated by the conductive member 3 can be adjusted to a desired value, so that the noise radiated from the electronic control device 1 can be easily reduced.

[0031] In addition, when a plurality of conductive members 3 are arranged, it is preferable to align the height of the contact surface 7h with which each conductive member 3 comes into contact and the height of each mounting surface 7g corresponding to each contact surface 7h. That is, it is preferable that the variation in the distance in the height direction of each of the mounting surface 7g and the contact surface 7h falls within a "predetermined range". By managing the heights of each contact surface 7h and each mounting surface 7g in this way, the contact electrical resistance generated by each conductive member 3 can be made closer, so that the generation of noise can be reduced. The "predetermined range" is determined based on the value of the contact electrical resistance that each conductive member 3 should generate, and it is preferable to set it so that the compressive force exerted on the plurality of conductive members 3 by the circuit board 2 and the plurality of contact surfaces 7h approaches an equal value.

[0032] (Second Embodiment) FIG. 3 is a cross-sectional view taken along line A-A shown in FIG. 1 of the electronic control device 1 according to the second embodiment of the present invention. The differences between the electronic control device 1 according to the present embodiment and the electronic control device 1 according to the first embodiment are as follows.

[0033] That is, the conductive member 3 is mounted not only on the base portion 7 side (first conductive member 3a) of the circuit board 2 but also on the cover portion 8 side (second conductive member 3b), and the cover portion 8 is also provided with a contact surface 8b where the metal substrate is exposed.

[0034] In addition, a plurality of first conductive members 3a are mounted on the circuit ground portion on the base portion 7 side of the circuit board 2, and the plurality of first conductive members 3a are in contact with the contact surface 7h of the base portion 7.

[0035] Hereinafter, the differences between the electronic control device 1 according to the present embodiment and the electronic control device 1 according to the first embodiment will be shown in detail.

[0036] In the circuit board 2 of the present embodiment, two first conductive members 3a are mounted on the circuit ground portion on the base portion 7 side, and one second conductive member 3b is mounted on the circuit ground portion on the cover portion 8 side.

[0037] The cover portion 8 of the present embodiment includes a protruding portion 8a that protrudes downward (-Y direction). A contact surface 8b where the metal substrate is exposed is provided at the lower end of the protruding portion 8a.

[0038] By mounting the circuit board 2 on the mounting surface 7g, each of the two first conductive members 3a is pressed against the contact surface 7h of the base portion, and the circuit board 2 and the base portion 7 are electrically connected via the two first conductive members 3a.

[0039] Then, by attaching the cover portion 8 to the upper part of the base portion 7 and fixing it with the screw 10, the second conductive member 3b is pressed against the contact surface 8b, and the second conductive member 3b and the cover portion 8 are electrically connected. [Effect] In the electronic control device of the present embodiment, the contact surface 7h of the base portion 7 is in contact with the first conductive member 3a, and the contact surface 8b of the cover portion 8 is in contact with the second conductive member 3b. Therefore, the electromagnetic radiation generated by the circuit board 2 can be released to both the base portion 7 and the cover portion 8, and the electromagnetic radiation (noise) can be further reduced.

[0040] Also, in the electronic control device of the present embodiment, the first conductive member 3a mounted on the lower surface of the circuit board 2 is pressed against the contact surface 7h of the base portion 7, and the second conductive member 3b mounted on the upper surface of the circuit board 2 is pressed against the contact surface 8b of the cover portion 8. Therefore, even if the electronic control device 1 moves up and down, the possibility of the electrical connection between the circuit board 2 and the metal housing 4 being disconnected can be reduced.

[0041] (Third Embodiment) FIG. 4 is a cross-sectional view taken along line A-A shown in FIG. 1 of the electronic control device 1 according to the third embodiment of the present invention. The electronic control device 1 according to the present embodiment is characterized in that a conductive gasket 3c is used as the conductive member.

[0042] The conductive gasket 3c is a component in which a conductive sheet is attached to a gasket such as a polyurethane foam, and is soldered to the circuit ground portion of the circuit board 2. Note that the portion denoted by reference numeral 11 in the figure indicates solder. [Effect] Since the electronic control device 1 of the present embodiment uses the conductive gasket 3c with a defined shape as the conductive member, a plurality of conductive members can be mounted in the same state like electronic components. As a result, for example, compared with the case where an adhesive is used as the conductive member, it becomes easier to manage the connection electrical resistance generated by the conductive gasket 3c, and noise can be easily reduced. Note that the height of the conductive gasket 3c is determined, and if an excessive compressive force acts, there is a possibility that the solder 11 may crack. However, as already described, in the present embodiment, since it is easy to manage the distance in the height direction between the contact surface 7h and the mounting surface 7g, such a situation can be avoided.

[0043] (Fourth Embodiment) FIG. 5 is a cross-sectional view taken along the line A-A shown in FIG. 1 of the electronic control device 1 according to the fourth embodiment of the present invention. The feature of the electronic control device 1 according to the present embodiment is that a conductive sealing material 3d is used as the conductive member.

[0044] The conductive sealing material 3d is, for example, a material in which a conductive filler is contained in a silicon adhesive, and is adhered to the circuit ground portion of the circuit board 2. The conductive sealing material 3d adhered to the circuit ground portion on the lower surface of the circuit board 2 adheres to the contact surface 7h by placing the circuit board 2 on the mounting surface 7g, and electrically connects the circuit board 2 and the base portion 7.

[0045] In addition, the conductive sealing material 3d adhered to the circuit ground portion on the upper surface of the circuit board 2 adheres to the contact surface 8b of the cover portion 8 by attaching and fixing the cover portion 8 to the upper part of the base portion 7, and electrically connects the circuit board 2 and the cover portion 8. [Effect] Even when the conductive sealing material 3d is used as the conductive member as in the present embodiment, noise can be reduced. In addition, since the conductive sealing material 3d is fixed by adhering to the circuit board 2, there is no need for soldering like the conductive gasket 3c, and the working efficiency can be improved. However, from the viewpoint of equalizing the amount of the conductive sealing material 3d in each part, it is preferable to use a coater.

[0046] Note that the conductive sealing material 3d may be a material containing a conductive filler in an acrylic adhesive. Further, as the conductive sealing material 3d, a Form-In-Place Gasket that can bond each of the contact surface 7h between the lower surface of the circuit board 2 and the base portion 7 and the contact surface 7h between the upper surface of the circuit board 2 and the cover portion 8 may be used. Also, a Cured-In-Place Gasket that bonds the conductive sealing material 3d to each of the lower surface and the upper surface of the circuit board 2 but not to the contact surface 7h of the base portion 7 and the contact surface 7h of the cover portion 8 may be used.

[0047] Note that the present invention is not limited to the above-described embodiments and includes various modifications. For example, the above-described embodiments have been described in detail for easy understanding of the present invention and are not necessarily limited to those having all the configurations described. Also, a part of the configuration of one embodiment can be replaced with the configuration of another embodiment, and the configuration of another embodiment can be added to the configuration of one embodiment. Further, for a part of the configuration of each embodiment, addition, deletion, or replacement with other configurations is possible.

[0048] Note that the embodiments of the present invention may also be as follows. The thin film insulation treatment on the surface of the metal housing 4 may be not only anodizing treatment but also other oxidation treatments, heat dissipation paints, cationic electrodeposition coating, anionic electrodeposition coating, etc. The thin film insulation treatment can exhibit a heat dissipation effect in any case of both the inner and outer surfaces of the metal housing 4, only the inner surface, or only the outer surface, but the heat dissipation effect is most excellent when both the inner and outer surfaces are treated. Also, the material of the metal housing 4 is not limited to aluminum or aluminum alloy, and other metals may be used.

Description of Reference Numerals

[0049] 1... Electronic control device, 2... Circuit board, 3, 3a, 3b... Conductive members, 3c... Conductive gasket, 3d... Conductive sealing material, 4... Metal housing, 5... Electronic components, 6... Connector, 7... Base portion, 7a... Recess, 7b... Fin, 7c... Bolt hole, 7d... Lower surface, 7e... First protrusion, 7f... Second protrusion, 7g... Mounting surface, 7h... Contact surface, 8... Cover portion, 8a... Protrusion, 8b... Contact surface

Claims

1. A circuit board on which electronic components are mounted, a plurality of conductive members mounted on the circuit board, a metal housing that houses the circuit board and has a thin-film insulation treatment applied to a metal base, a mounting surface on the metal housing on which the circuit board is mounted, and a plurality of contact surfaces on the metal housing where the plurality of conductive members come into contact, wherein the metal base is exposed at the mounting surface and the plurality of contact surfaces, the plurality of contact surfaces are located below the mounting surface, the plurality of conductive members are arranged along a first direction, and the mounting surface is disposed opposite the plurality of conductive members with a gap therebetween in a second direction orthogonal to the first direction, An electronic control device, characterized in that distances in the height direction of each of the mounting surface and the plurality of contact surfaces are made uniform in order to approximate values of contact electrical resistance generated in each of the plurality of conductive members.

2. The electronic control device according to claim 1, wherein the metal housing includes a base portion on which the circuit board is placed and a cover portion attached to an upper portion of the base portion and covering the circuit board, and the mounting surface and the contact surfaces are provided on the base portion.

3. The electronic control device according to claim 1, wherein the metal housing includes a base portion on which the circuit board is placed and a cover portion attached to an upper portion of the base portion and covering the circuit board, the plurality of conductive members are mounted on a lower surface of the circuit board, and the plurality of contact surfaces are located on the base portion, and further includes other conductive members that are mounted on an upper surface of the circuit board and are in contact with contact surfaces located on the cover portion.

4. The electronic control device according to claim 1, characterized in that at least one of the circuit board and the metal housing is grounded.

5. The electronic control device according to claim 1, characterized in that the thin-film insulation treatment is an alumite treatment.

6. The electronic control device according to claim 1, characterized in that the plurality of conductive members are conductive gaskets soldered to the circuit board.

7. The electronic control device according to claim 1, characterized in that the plurality of conductive members are conductive sealing materials.

8. The electronic control device according to claim 7, An electronic control device, characterized in that the conductive sealing material is a material containing a conductive filler in a silicon adhesive.

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