Electronic control unit

Abstract

This electronic control device comprises: a housing made up of a housing base and a housing cover; a first circuit board that is attached to the housing base and to which an electronic component is mounted; and a second circuit board that is attached to the housing base and that is electrically connected to the first circuit board via a board-to-board connector. The housing base has a first pedestal for attaching the first circuit board, a second pedestal for attaching the second circuit board, and a first wall part arranged with a predetermined step on the outside of the first pedestal, and a first heat conduction member is provided between the inner surface of the housing base and an electronic component facing the inner surface.

Description

Technical Field

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

Background Art

[0002] Generally, a plurality of electronic control units (ECUs) are mounted on vehicles such as automobiles. An electronic control device mounted on a vehicle (hereinafter also referred to as an "in-vehicle electronic control device") has a structure in which a circuit board on which electronic components are mounted is housed inside a housing. The housing is composed of a housing base to which the circuit board is attached and a housing cover that forms a space for housing the circuit board between the housing base.

[0003] In recent years, the functionality of in-vehicle electronic control devices, including those for autonomous driving, has advanced, and the heat generation of electronic components has increased. When the temperature of an electronic component rises above the rated temperature, it may lead to a failure and cause defects in the electronic control device. Therefore, in order to suppress the temperature rise due to the heat generation of electronic components, measures have been taken to release the heat of the electronic components to the housing base using a TIM (Thermal Interface Material) such as thermal conductive grease (see, for example, Patent Document 1). In this measure, the housing base functions as a heat sink.

[0004] Conventionally, in order to lower the temperature of an electronic component, for example, a TIM is disposed between the upper surface of the electronic component and the housing base facing the upper surface, and the heat of the electronic component is released to the housing base through the TIM. Furthermore, improvements have been made to enhance the heat dissipation performance, such as expanding the TIM to cover the entire side surface of the electronic component and the surrounding substrate. The heat dissipation structure using a TIM has become an effective heat dissipation structure in in-vehicle electronic control devices with significant advancements in functionality, such as control devices for autonomous driving.

Prior Art Documents

Patent Documents

[0005]

Patent Document 1

[0006] Incidentally, some in-vehicle electronic control devices have two circuit boards of different sizes, for example, a main circuit board (hereinafter also referred to as the "main board") and a sub-circuit board (hereinafter also referred to as the "sub-board"). In this type of in-vehicle electronic control device, the two circuit boards are electrically connected by a board-to-board connector (BtoB connector), and a spacer is placed between the two circuit boards.

[0007] In a scenario where two circuit boards are electrically connected via a board-to-board connector, and electronic components are mounted on a sub-board positioned between the enclosure base and a spacer, and heat from these electronic components is dissipated to the enclosure base using a TIM (Thermal Insulation Module), variations in the thickness of the sub-board and spacer can increase the TIM's thickness (heat dissipation distance), sometimes preventing sufficient heat from the electronic components from being dissipated to the enclosure base.

[0008] The object of the present invention is to provide an electronic control device that can efficiently dissipate heat from electronic components mounted on the circuit board on the housing base side of two circuit boards connected via a board-to-board connector to the housing base. [Means for solving the problem]

[0009] To address the above issues, for example, the configuration described in the claims may be adopted. The present invention includes multiple means for solving the above problems, but one example is an electronic control device comprising: a housing consisting of a housing base and a housing cover; a first circuit board mounted on the housing base and having electronic components mounted in a position facing the inner surface of the housing base; and a second circuit board mounted on the housing base, having larger external dimensions than the first circuit board, and electrically connected to the first circuit board via a board-to-board connector. The housing base has a first base for mounting the first circuit board, a second base for mounting the second circuit board, and a first wall portion arranged outside the first base with a predetermined step, and a first heat conductive member is provided between the inner surface of the housing base and the electronic components facing it. [Effects of the Invention]

[0010] According to the present invention, heat from electronic components mounted on the circuit board on the housing base side of two circuit boards connected via a board-to-board connector can be efficiently dissipated to the housing base. Other issues, configurations, and effects not mentioned above will be clarified by the following description of the embodiments. [Brief explanation of the drawing]

[0011] [Figure 1] This is an exploded perspective view of the electronic control device according to the first embodiment, viewed from an oblique angle above. [Figure 2] This is an exploded perspective view of the electronic control device according to the first embodiment, viewed from a diagonal downward angle. [Figure 3] This is a cross-sectional view illustrating the configuration of an electronic control device according to the first embodiment. [Figure 4] This is a cross-sectional view illustrating the configuration of an electronic control device according to the second embodiment. [Figure 5] This is a cross-sectional view illustrating the configuration of an electronic control device according to the third embodiment. [Figure 6] This is a cross-sectional view illustrating the configuration of an electronic control device according to the fourth embodiment. [Figure 7]It is a cross-sectional view for explaining the configuration of the electronic control device according to the fifth embodiment. [Figure 8] It is a cross-sectional view for explaining the configuration of the electronic control device according to the sixth embodiment. [Figure 9] It is a cross-sectional view for explaining the configuration of the electronic control device according to the seventh embodiment. [Figure 10] It is a cross-sectional view for explaining the configuration of the electronic control device according to the eighth embodiment. [Figure 11] It is a cross-sectional view for explaining the configuration of the electronic control device according to the ninth embodiment. [Figure 12] It is a cross-sectional view for explaining the configuration of the electronic control device according to the tenth embodiment. [Figure 13] It is a cross-sectional view for explaining the configuration of the electronic control device according to the eleventh embodiment. [Figure 14] It is a cross-sectional view for explaining the configuration of the electronic control device according to the twelfth embodiment.

Embodiments for Carrying Out the Invention

[0012] Hereinafter, embodiments of the present invention will be described in detail with reference to the drawings. In this specification and the drawings, elements having substantially the same function or configuration are denoted by the same reference numerals, and redundant explanations are omitted.

[0013] <First Embodiment> FIG. 1 is an exploded perspective view of the electronic control device according to the first embodiment as viewed obliquely from above. FIG. 2 is an exploded perspective view of the electronic control device according to the first embodiment as viewed obliquely from below. FIG. 3 is a cross-sectional view for explaining the configuration of the electronic control device according to the first embodiment. In the cross-sectional view of FIG. 3, the cross-sectional position is appropriately shifted so that the structural features of the electronic control device appear, and the notation of the cover is omitted. This is the same for the cross-sectional views for explaining the configurations of the electronic control devices according to other embodiments described later.

[0014] As shown in FIGS. 1 to 3, the electronic control device 10 includes a housing composed of a housing base 11 and a housing cover 12, a first circuit board 14, and a second circuit board 15. The electronic control device 10 is preferably applied to an in-vehicle electronic control device and is used for an automatic driving control device that controls or supports the operation of a vehicle, a control device that performs high-frequency communication, and the like. Further, the electronic control device 10 can be widely applied to, for example, electronic control devices such as millimeter-wave radars and in-vehicle cameras. However, the object controlled by the electronic control device 10 is not limited to a specific object.

[0015] The housing base 11 is made of copper (including copper alloys), aluminum (including aluminum alloys), etc., which are metals with high thermal conductivity, and functions as a heat sink. In that case, a flow path (not shown) may be formed in the housing base 11, and a so-called liquid-cooled heat sink in which a refrigerant is flowed through this flow path may be adopted. The housing base 11 is, for example, a casting obtained by aluminum die casting. However, since it is difficult to obtain high dimensional accuracy for castings, it is preferable to enhance the dimensional accuracy of a part of the housing base 11 by machining. The housing base 11 has a flat plate portion 21 that is square in plan view and side plate portions 22 that extend along the outer periphery of the flat plate portion 21. Recesses 22a are formed in the side plate portions 22 to avoid interference with connectors (31, 32) described later.

[0016] As shown in FIGS. 2 and 3, the housing base 11 integrally has a first pedestal​​​As shown in Figures 2 and 3, the first wall portion 18 is formed in the shape of a square frame. The first wall portion 18 is arranged to surround the first circuit board 14. The first base 16 is provided at the four corners within the frame of the first wall portion 18. Screw holes are provided in the first base 16. The first wall portion 18 is formed to protrude from the inner surface 11a of the flat plate portion 21 of the housing base 11 in the thickness direction of the housing base 11. A predetermined step D is provided between the protruding end portion 18a of the first wall portion 18 and the first base 16. The predetermined step D is set according to the height dimension of the board-to-board connectors (26, 30) which will be described later. As shown in Figure 3, the protruding end portion 18a of the first wall portion 18 is positioned in contact with or close to the board surface of the second circuit board 15 in order to maintain the distance between the first circuit board 14 and the second circuit board 15 at a distance suitable for the height dimension of the board-to-board connectors. The first wall portion 18 is positioned outside the first base 16 and inside the second base 17. Preferably, the first wall portion 18 is formed with frame dimensions slightly larger than the outer dimensions of the first circuit board 14.

[0018] The second base 17 is positioned further outward than the first base 16. Specifically, the second base 17 is positioned at the four corners of the housing base 11 together with the cover mounting base 19. The second base 17 is also positioned slightly inward than the cover mounting base 19. Screw holes are provided in both the second base 17 and the cover mounting base 19. In the thickness direction of the housing base 11, the cover mounting base 19 is positioned further away from the inner surface 11a of the flat plate portion 21 (at the lower end of the side plate portion 22) than the second base 17.

[0019] The housing cover 12 is made of, for example, sheet metal. The housing cover 12 is formed in a rectangular, flat shape when viewed from above. The housing cover 12 forms a circuit board storage space between itself and the housing base 11. The first circuit board 14 and the second circuit board 15 are housed in the circuit board storage space formed by the housing base 11 and the housing cover 12. Through holes 23 are provided at the four corners of the housing cover 12. The housing cover 12 is fixed to the cover mounting base 19 of the housing base 11 using screws 24 as cover fasteners. The screws 24 engage with the screw holes of the cover mounting base 19 through the through holes 23 of the housing cover 12. The housing cover 12 is fixed to the housing base 11 by the tightening force of the screws 24 with its four corners abutting against the cover mounting base 19.

[0020] The first circuit board 14 is, for example, a printed wiring board with glass epoxy as the substrate. An electronic component 25 is mounted on one substrate surface of the first circuit board 14. The electronic component 25 is mounted in a position facing the inner surface 11a of the flat plate portion 21 of the housing base 11. The electronic component 25 is an electronic component that generates a large amount of heat per unit time, such as a semiconductor element such as a CPU, MPU, or GPU with a high operating frequency, or a power semiconductor. Specifically, the electronic component 25 is preferably an electronic component that generates more than 30W of heat per unit time, more preferably more than 50W, and even more preferably more than 100W.

[0021] A first heat conductive member 20 is provided between the inner surface 11a of the housing base 11 and the electronic component 25 facing it. The first heat conductive member 20 is in contact with both the housing base 11 and the electronic component 25. The first heat conductive member 20 is made of, for example, a heat conductive adhesive, heat conductive grease, or heat conductive sheet. As a result, the electronic component 25 is thermally connected to the housing base 11 via the first heat conductive member 20. The number of electronic components 25 thermally connected to the housing base 11 via the first heat conductive member 20 is not limited to one, but may be multiple.

[0022] On the other hand, a board-to-board connector 26 is mounted on the other board surface of the first circuit board 14. The board-to-board connector 26 is mounted in a position opposite to the second circuit board 15. In addition to the electronic components 25 and board-to-board connector 26 mentioned above, other electronic components and connectors are also mounted on the first circuit board 14, but their explanation is omitted here.

[0023] Through holes 27 are provided at the four corners of the first circuit board 14. The first circuit board 14 is fixed to the first base 16 of the housing base 11 using screws 28, which serve as first fasteners. The screws 28 engage with the screw holes of the first base 16 through the through holes 27 of the first circuit board 14. The first circuit board 14 is fixed to the housing base 11 by the tightening force of the screws 28, with its four corners abutting against the first base 16.

[0024] In the first embodiment, the first circuit board 14 is directly fixed to the first base 16 of the housing base 11 using screws 28. However, there should be at least one such direct fixing point, and it is preferable to have two or more points to account for displacement of the first circuit board 14 due to vibration, mechanical shock, etc.

[0025] The second circuit board 15 is, for example, a printed wiring board with glass epoxy as the base material. As shown in Figure 1, an electronic component 29, a board-to-board connector 30, a first connector 31 for external connection, and a second connector 32 for external connection are mounted on one side of the second circuit board 15. The board-to-board connector 30 is a connector that has a male-to-female relationship with the board-to-board connector 26 (in other words, a connector that can be mated with the board-to-board connector 26), and is mounted in a position opposite the first circuit board 14. The board-to-board connector 30 electrically connects the first circuit board 14 and the second circuit board 15 by mating with the board-to-board connector 26. The first connector 31 is, for example, a connector for electrically connecting the electronic control device 10 with other in-vehicle electronic control devices (not shown). The second connector 32 is, for example, a connector for connecting a vehicle wire harness (not shown). In addition to the electronic components 29, board-to-board connector 30, first connector 31, and second connector 32 mentioned above, the second circuit board 15 also has other electronic components and connectors mounted on it, but these will not be explained here.

[0026] The second circuit board 15 is provided with through holes 33. The second circuit board 15 is fixed to the second base 17 of the housing base 11 using screws 34, which serve as second fasteners. The screws 34 engage with the screw holes of the second base 17 through the through holes 33 of the second circuit board 15. The second circuit board 15 is fixed to the housing base 11 by the tightening force of the screws 34, with its four corners abutting against the second base 17.

[0027] In the first embodiment, the second circuit board 15 is directly fixed to the second base 17 of the housing base 11 using screws 24. However, there should be at least one such point of direct fixing, and it is preferable to have two or more points of direct fixing to account for displacement of the second circuit board 15 due to vibration, mechanical shock, etc.

[0028] In the electronic control device 10 according to the first embodiment described above, the first circuit board 14 is mounted on the first base 16 of the housing base 11. Furthermore, a first wall portion 18 is arranged on the outside of the first base 16 of the housing base 11 with a predetermined step D. As a result, the distance between the first circuit board 14 and the second circuit board 15 is maintained at a distance suitable for the height dimensions of the board-to-board connectors 26 and 30. Therefore, there is no need to place a spacer between the first circuit board 14 and the second circuit board 15. Consequently, the distance between the inner surface 11a of the housing base 11 and the board surface of the first circuit board 14 facing it is determined mainly by the dimensions of the housing base 11 itself, without being affected by variations in the thickness of the circuit boards or the thickness variations of the spacers. As a result, the thickness dimension of the first heat conductive member 20 can be kept small, and the heat of the electronic components 25 can be efficiently dissipated to the housing base 11. Furthermore, the heat generated by the electronic components 25 and other electronic components mounted on the first circuit board 14 can be dissipated to the housing base 11 through the first base 16. This improves the cooling efficiency of the electronic components 25 and the first circuit board 14. In particular, by machining the inner surface 11a of the housing base 11 that contacts the first heat conductive member 20 and the first base 16 to which the first circuit board 14 is attached, the relative positional accuracy between the housing base 11 and the first circuit board 14 can be improved, enabling further thinning of the first heat conductive member 20 and increasing cooling efficiency. In addition, the gap between the first circuit board 14 and the second circuit board 15 is maintained by the step D between the first base 16 and the first wall portion 18, thus maintaining a good mating state of the board-to-board connectors 26 and 30. This improves the reliability of the connection of the board-to-board connectors 26 and 30.

[0029] Furthermore, the first wall portion 18 is positioned to surround the first circuit board 14. This allows the first wall portion 18 to shield electromagnetic waves radiated from the pattern wiring of the first circuit board 14 and the pattern wiring of the second circuit board 15. Thus, malfunctions of other electronic control devices mounted on the vehicle, or electronic control devices brought into the vehicle, can be prevented.

[0030] In the first embodiment, a preferred example is a configuration in which the first circuit board 14 is surrounded all around by a first wall portion 18. However, the configuration is not limited to this, and even if the first wall portion 18 is provided only on a part of the perimeter of the first circuit board 14, the cooling efficiency and electromagnetic shielding performance will be higher compared to when the first wall portion 18 is not provided.

[0031] Furthermore, in the first embodiment, a screw 28 is used as the first fastener and a screw 34 is used as the second fastener, but the fastener is not limited to a screw, and may be a rivet, crimp, adhesive, etc. If an adhesive is used as the fastener, the electromagnetic shielding performance can be enhanced by using a conductive adhesive to electrically connect the circuit ground of the first circuit board 14 to the housing base 11, and the circuit ground of the second circuit board 15 to the housing base 11, via the conductive adhesive. Similarly, if a screw, rivet, or crimp is used as the fastener, the electromagnetic shielding performance can be enhanced by electrically connecting the circuit ground of the first circuit board 14 to the housing base 11, and the circuit ground of the second circuit board 15 to the housing base 11, via the fastener.

[0032] <Second Embodiment> Figure 4 is a cross-sectional view illustrating the configuration of an electronic control device according to the second embodiment. The electronic control device 10A according to the second embodiment differs from the first embodiment (Figure 3) in that two protrusions 36 are provided at the tip of the first wall portion 18, and two positioning holes 37 are provided in the second circuit board 15 corresponding to these protrusions 36. The protrusions 36 are formed, for example, in a conical shape, and the positioning holes 37 are formed, for example, in a circular shape.

[0033] When attaching the second circuit board 15 to the second base 17 of the housing base 11 using screws 34, the projection 36 of the first wall portion 18 is inserted through the positioning hole 37 of the second circuit board 15. This positions the second circuit board 15 relative to the housing base 11 and defines the relative position of the first circuit board 14 and the second circuit board 15. As a result, the alignment accuracy of the board-to-board connector 26 and the board-to-board connector 30 is improved, making it easier to mate the connectors together.

[0034] In the second embodiment, there are two projections 36 and two positioning holes 37, but the number of each may be three or more.

[0035] <Third Embodiment> Figure 5 is a cross-sectional view illustrating the configuration of an electronic control device according to the third embodiment. The electronic control device 10B according to the third embodiment differs from the first embodiment described above (Figure 3) in that the second circuit board 15 is fixed to the protruding end 18a of the first wall portion 18 by a screw 38. In this case, the protruding end 18a of the first wall portion 18 constitutes a "third base" for attaching the second circuit board 15, and the screw 38 corresponds to a "third fastener" for fixing the second circuit board 15 to the first wall portion 18 having the third base.

[0036] A screw hole is provided at the protruding end 18a of the first wall portion 18. The second circuit board 15 is also provided with a through hole for inserting a screw 38. The screw 38 engages with the screw hole of the first wall portion 18 through the through hole of the second circuit board 15. The second circuit board 15 is fixed to the first wall portion 18 by the tightening force of the screw 38, with the protruding end 18a of the first wall portion 18 abutting against it.

[0037] By fixing the second circuit board 15 to the first wall portion 18 with screws 38 in this manner, movement of the mating portions of the board-to-board connectors 26 and 30 due to mechanical shocks, vibrations, temperature changes, etc., can be suppressed, thereby improving the reliability of the connection between the connectors.

[0038] Furthermore, the second circuit board 15 is directly fixed to the first wall portion 18 with screws 38 at least one location, and it is desirable to have two or more locations to further improve the reliability of the connection between the connectors.

[0039] Furthermore, in the third embodiment, a screw 34 is used as the third fastener, but the third fastener is not limited to a screw, and may be a rivet, crimp, adhesive, etc. Also, when an adhesive is used as the third fastener, by using a conductive adhesive, the electromagnetic shielding performance can be enhanced by electrically connecting the circuit ground of the first circuit board 14 to the housing base 11 and the circuit ground of the second circuit board 15 to the housing base 11 via the conductive adhesive. Similarly, when a screw, rivet, or crimp is used as the third fastener, the electromagnetic shielding performance can be enhanced by electrically connecting the circuit ground of the first circuit board 14 to the housing base 11 and the circuit ground of the second circuit board 15 to the housing base 11 via the fastener.

[0040] <Fourth Embodiment> Figure 6 is a cross-sectional view illustrating the configuration of the electronic control device according to the fourth embodiment. The electronic control device 10C according to the fourth embodiment differs from the first embodiment described above (Figures 1 to 3) in that a first notch 39 is provided in the first wall portion 18 which is arranged to surround the first circuit board 14, and the second circuit board 15 is fixed to the first wall portion 18 by screws 38. Of these, the fact that the second circuit board 15 is fixed to the first wall portion 18 by screws 38 is the same as in the third embodiment described above (Figure 5).

[0041] The first notch 39 is provided in the first wall portion 18 in such a way that it forms a gap between it and the second circuit board 15. The width W and height H of the first notch 39 are set to be less than or equal to the wavelength of the electrical signal flowing through the board-to-board connectors 26, 30 (Figure 3), more preferably half a wavelength or less. Furthermore, the width W and height H of the first notch 39 are set to dimensions that avoid integer fractions of the wavelength of the electrical signal flowing through the board-to-board connectors 26, 30. For example, if the wavelength of the electrical signal flowing through the board-to-board connectors 26, 30 is 18.7 mm, then the width W and height H of the first notch 39 are both set to 18.7 mm or less, and the width W and height H of the first notch 39 are set to values ​​that avoid 18.7 mm / integer. This makes it possible to enhance the electromagnetic shielding effect of the first wall portion 18 even when the first notch 39 is provided in the first wall portion 18.

[0042] Furthermore, by providing a first notch 39 in the first wall portion 18, the pattern wiring of the second circuit board 15 can be laid out below the first notch 39. This makes it easier to lay out the pattern wiring of the second circuit board 15. If the first notch 39 is not provided in the first wall portion 18, the pattern wiring of the second circuit board 15 cannot be laid out below the first notch 39, so it is necessary to provide through holes in multiple locations on the second circuit board 15 to lay out the pattern wiring. Therefore, if the first notch 39 is not provided in the first wall portion 18, the length of the pattern wiring will be long and there is a risk of signal quality deterioration, but if the first notch 39 is provided in the first wall portion 18, the length of the pattern wiring can be kept short and signal quality can be improved.

[0043] <Fifth Embodiment> Figure 7 is a cross-sectional view illustrating the configuration of the electronic control device according to the fifth embodiment. The electronic control unit 10D according to the fifth embodiment differs from the fourth embodiment described above (Figure 6) in that a high-speed transmission line 40 is formed on the second circuit board 15, and this high-speed transmission line 40 is positioned to correspond to the first notch 39. The high-speed transmission line 40 is formed as part of the pattern wiring of the second circuit board 15. Specific examples of the high-speed transmission line 40 include high-speed transmission lines such as PCIe, HSGMII, MIPI C-PHY, USB, and DisplayPort. The high-speed transmission line 40 is formed on the second circuit board 15 so as to pass under the first notch 39.

[0044] By arranging the high-speed transmission line 40 on the second circuit board 15 in this way, the length of the high-speed transmission line 40 can be shortened and the quality of the electrical signals flowing through the high-speed transmission line 40 can be improved compared to the case where through-holes are provided at multiple locations on the second circuit board 15 to lay out the high-speed transmission line.

[0045] <Sixth Embodiment> Figure 8 is a cross-sectional view illustrating the configuration of the electronic control device according to the sixth embodiment. The electronic control device 10E according to the sixth embodiment differs from the fourth embodiment described above (Figure 6) in that a first electrical connection point 41 is provided in a part of the gap formed by the first notch 39. The first electrical connection point 41 is provided so as to be in contact with the housing base 11 and the second circuit board 15. Furthermore, the widths w1, w2 and height H of the first notch 39, excluding the first electrical connection point 41, are set to be less than or equal to the wavelength of the electrical signal flowing through the board-to-board connectors 26, 30 (Figure 3), more preferably half a wavelength or less. In addition, the widths w1, w2 and height H of the first notch 39 are set to dimensions that avoid integer fractions of the wavelength of the electrical signal flowing through the board-to-board connectors 26, 30.

[0046] The first electrical connection point 41 can have any configuration as long as it can electrically connect the housing base 11 and a part of the second circuit board 15 (for example, the circuit ground). For example, the first electrical contact point 41 can be made of a screw, conductive adhesive, electromagnetic shielding material, etc. An electrical connection refers to a connection that satisfies conditions such as low resistance or low impedance, either DC or AC.

[0047] By providing a first electrical connection point 41 in a portion of the gap formed by the first notch 39, for example, even if the total width W of the first notch 39 exceeds the wavelength of the electrical signal flowing through the board-to-board connectors 26 and 30, the widths w1 and w2 of the first notch 39 can be kept below the wavelength of the electrical signal. Therefore, the first notch 39 can be formed with a wider width on the second circuit board 15, increasing the freedom of the pattern wiring layout.

[0048] <Seventh Embodiment> Figure 9 is a cross-sectional view illustrating the configuration of the electronic control device according to the seventh embodiment. The electronic control unit 10F according to the seventh embodiment differs from the third embodiment described above (Figure 5) in that multiple heat-generating components 42 are arranged near the screw 38, which serves as the third fastener. The multiple heat-generating components 42 are mounted on both sides of the second circuit board 15. Furthermore, of the multiple heat-generating components 42, one heat-generating component 42 is positioned inside the first wall portion 18, while the other heat-generating components 42 are positioned outside the first wall portion 18.

[0049] Here, at the fixing point by the screw 38, the second circuit board 15 is in contact (tightly attached) to the first wall portion 18, so the temperature of the second circuit board 15 near the screw 38 is lower than other parts of the board. Therefore, by placing the heat-generating component 42 near the screw 38, the heat from the heat-generating component 42 can be efficiently dissipated to the housing base 11 through the first wall portion 18. Thus, even if the heat-generating component 42 is an electronic component with a low rated temperature, for example, the temperature of this electronic component can be kept low. Note that the number of heat-generating components 42 placed near the screw 38 can be one or multiple.

[0050] <Eighth Embodiment> Figure 10 is a cross-sectional view illustrating the configuration of an electronic control device according to the eighth embodiment. The electronic control device 10G according to the eighth embodiment differs from the fourth embodiment described above (Figure 6) in that a second heat conductive member 45 is provided in a part of the gap formed by the first notch 39, and a plurality of heat-generating components 46 are mounted on the second circuit board 15 so as to be located near the second heat conductive member 45.

[0051] The second heat conductive member 45 is made of, for example, a heat conductive adhesive, heat conductive grease, or heat conductive sheet. The second heat conductive member 45 is in contact with both the housing base 11 and the second circuit board 15. As a result, the second circuit board 15 is thermally connected to the housing base 11 via the second heat conductive member 45. Multiple heat-generating components 46 are mounted on both sides of the second circuit board 15. Of the multiple heat-generating components 46, one heat-generating component 46 is mounted next to the second heat conductive member 45, while the other heat-generating components 46 are mounted on the opposite side of the second circuit board 15 from the second heat conductive member 45.

[0052] Here, where the second heat conductive member 45 is provided, the second circuit board 15 is in contact with the second heat conductive member 45, so the temperature of the second circuit board 15 in the vicinity of the second heat conductive member 45 is lower than that of other parts of the board. Therefore, by placing the heat-generating component 46 in the vicinity of the second heat conductive member 45, the heat from the heat-generating component 46 can be efficiently dissipated to the housing base 11 via the second heat conductive member 45. Thus, even if the heat-generating component 46 is an electronic component with a low rated temperature, for example, the temperature of this electronic component can be kept low. Note that the number of heat-generating components 46 placed in the vicinity of the second heat conductive member 45 may be one or more.

[0053] <Ninth Embodiment> Figure 11 is a cross-sectional view illustrating the configuration of an electronic control device according to the ninth embodiment. The electronic control device 10H according to the ninth embodiment differs from the sixth embodiment described above (Figure 8) in that multiple heat-generating components 50 are mounted on the second circuit board 15 so as to be located near the first electrical connection point 41. The multiple heat-generating components 50 are mounted on both sides of the second circuit board 15. Furthermore, of the multiple heat-generating components 50, one heat-generating component 46 is mounted next to the first electrical connection point 41, and the heat-generating components 50 are mounted on the opposite side of the first electrical connection point 41, with the second circuit board 15 in between.

[0054] The first electrical connection point 41 is composed of, for example, a screw, conductive adhesive, or electromagnetic shielding material, which has high electrical and thermal conductivity. Therefore, by bringing the first electrical connection point 41 into contact with both the housing base 11 and the second circuit board 15, the housing base 11 and the second circuit board 15 are electrically and thermally connected via the first electrical connection point 41. Consequently, the temperature of the second circuit board 15 near the first electrical connection point 41 is lower than that of other parts of the board. Therefore, by placing a heat-generating component 50 near the first electrical connection point 41, the heat from the heat-generating component 50 can be efficiently dissipated to the housing base 11 via the first electrical connection point 41. Consequently, even if the heat-generating component 50 is an electronic component with a low rated temperature, the temperature of this electronic component can be kept low. The number of heat-generating components 50 placed near the first electrical connection point 41 may be one or multiple.

[0055] <Tenth Embodiment> Figure 12 is a cross-sectional view illustrating the configuration of an electronic control device according to the 10th embodiment. The electronic control device 10J according to the tenth embodiment differs from the first embodiment described above (Figures 1 to 3) in that a second wall portion 52 is provided on the housing base 11. The second wall portion 52 is provided further inward than the first wall portion 18. The second wall portion 52 is also formed in a rectangular frame shape so as to surround the electronic components (Figures 1 and 3) mounted on the first circuit board 14. Furthermore, the end portion 52a of the second wall portion 52 in the thickness direction of the housing base 11 is arranged to form a coplanar plane with the first base 16.

[0056] By providing the second wall portion 52 on the housing base 11 in this manner, electromagnetic waves radiated from the pattern wiring of the first circuit board 14 can be shielded by the second wall portion 52. Therefore, malfunctions of other electronic control devices mounted on the vehicle, or electronic control devices brought into the vehicle, can be prevented.

[0057] <Embodiment 11> Figure 13 is a cross-sectional view illustrating the configuration of an electronic control device according to the 11th embodiment. The electronic control device 10K according to the 11th embodiment differs from the case of the 10th embodiment described above (Figure 12) in that a second notch 53 is provided in the second wall portion 52, and a third heat conductive member 54 is provided in a part of the gap formed by the second notch portion 53. The second notch portion 53 is provided in such a way that it forms a gap between the second wall portion 52 and the first circuit board 14.

[0058] The third heat conductive member 54 is provided so as to be in contact with the housing base 11 (second wall portion 52) and the first circuit board 14. The third heat conductive member 54 is made of, for example, a thermal conductive adhesive, thermal conductive grease, thermal conductive sheet, etc. As a result, the first circuit board 14 is thermally connected to the housing base 11 via the third heat conductive member 54.

[0059] By providing a second notch 53 in the second wall portion 52 and a third heat conductive member 54 in this second notch portion 53, the heat generated in the first circuit board 14 can be efficiently dissipated to the housing base 11 via the third heat conductive member 54.

[0060] <Twelfth Embodiment> Figure 14 is a cross-sectional view illustrating the configuration of an electronic control device according to the 12th embodiment. The electronic control device 10L according to the 12th embodiment differs from the 10th embodiment described above (Figure 12) in that a second notch 53 is provided in the second wall portion 52, and a second electrical connection point 55 is provided in a part of the gap formed by the second notch portion 53. The second notch portion 53 is provided in such a way that it forms a gap between the second wall portion 52 and the first circuit board 14.

[0061] The second electrical connection point 55 is provided so as to be in contact with the housing base 11 (second wall portion 52) and the first circuit board 14. Furthermore, the width and height of the second notch 53, excluding the second electrical connection point 55, are set to be less than or equal to the wavelength of the electrical signal flowing through the pattern wiring of the first circuit board 14, more preferably half a wavelength or less. In addition, the width and height of the second notch 53 described above are set to dimensions that avoid integer fractions of the wavelength of the electrical signal flowing through the pattern wiring of the first circuit board 14.

[0062] The second electrical connection point 55 can have any configuration as long as it can electrically connect the housing base 11 and a part of the first circuit board 14 (for example, the circuit ground). For example, the second electrical connection point 55 can be made of a screw, conductive adhesive, electromagnetic shielding material, etc.

[0063] By providing a second electrical connection point 55 in a portion of the gap formed by the second notch 53, the electromagnetic shielding effect of the second wall 52 can be enhanced, for example, even if the total width of the second notch 53 exceeds the wavelength of the electrical signal flowing through the pattern wiring of the first circuit board 14.

[0064] It should be noted that the present invention is not limited to the embodiments described above, but includes various modifications. For example, although the embodiments described above are explained in detail to make the content of the present invention easier to understand, the present invention is not necessarily limited to having all the configurations described in the embodiments described above. Furthermore, it is possible to replace a part of the configuration of one embodiment with the configuration of another embodiment. It is also possible to add the configuration of another embodiment to the configuration of one embodiment. Furthermore, it is possible to delete, add, or replace a part of the configuration of each embodiment. [Explanation of Symbols]

[0065] 10, 10A, 10B, 10C, 10D, 10E, 10F, 10G, 10H, 10J, 10K, 10L…Electronic control unit, 11…Enclosure base, 11a…Inner surface, 12…Enclosure cover, 14…First circuit board, 15…Second circuit board, 16…First base, 17…Second base, 18…First wall, 25…Electronic component, 26, 30…Board-to-board connector, 36…Protrusion, 37…Position 28…Screw (first fastener), 34…Screw (second fastener), 38…Screw (third fastener), 39…First notch, 40…High-speed transmission line, 41…First electrical connection point, 42…Heat-generating component, 45…Second heat-conducting member, 46…Heat-generating component, 50…Heat-generating component, 52…Second wall, 53…Second notch, 54…Third heat-conducting member, 55…Second electrical connection point

Claims

1. The enclosure consists of an enclosure base and an enclosure cover, A first circuit board is attached to the housing base and has electronic components mounted on it at a position facing the inner surface of the housing base, The second circuit board is mounted on the housing base, has larger external dimensions than the first circuit board, and is electrically connected to the first circuit board via a board-to-board connector, The housing base includes a first base for mounting the first circuit board, a second base for mounting the second circuit board, and a first wall portion arranged outside the first base with a predetermined step. A first heat conductive member is provided between the inner surface of the housing base and the electronic component facing it. Electronic control unit.

2. The first wall portion is arranged to surround the first circuit board. The electronic control device according to claim 1.

3. The second circuit board has at least two positioning holes, The first wall portion is provided with a projection that passes through the positioning hole. The electronic control device according to claim 1.

4. The first circuit board is fixed to the first base by a first fastener. The second circuit board is fixed to the second base by a second fastener and to the first wall by a third fastener. The electronic control device according to claim 1.

5. The first wall portion is provided with a first notch portion such that it forms a gap between it and the second circuit board. The width and height of the first notch are less than or equal to the wavelength of the electrical signal flowing through the board-to-board connector. The electronic control device according to claim 1.

6. The second circuit board has a high-speed transmission line positioned at a location corresponding to the first notch. The electronic control device according to claim 5.

7. A first electrical connection point is provided in a portion of the gap formed by the first notch so as to be in contact with the housing base and the second circuit board, and the width and height of the first notch, excluding the electrical connection point, are less than or equal to the wavelength of the electrical signal flowing through the board-to-board connector. The electronic control device according to claim 5.

8. The second circuit board has heat-generating components mounted on it so as to be located near the third fixing device. The electronic control device according to claim 4.

9. A second heat conductive member is provided in a part of the gap formed by the first notch so as to be in contact with the housing base and the second circuit board. The second circuit board has heat-generating components mounted on it so as to be located near the second heat-conducting member. The electronic control device according to claim 5.

10. The second circuit board has a heat-generating component mounted on it so as to be located near the first electrical connection point. The electronic control device according to claim 7.

11. The housing base has a second wall portion located inside the first wall portion. The electronic control device according to claim 1.

12. The second wall portion is provided with a second notch that forms a gap between it and the first circuit board, and a third heat conductive member is provided in a part of the gap formed by the second notch so as to be in contact with the housing base and the first circuit board. The electronic control device according to claim 11.

13. The second wall portion is provided with a second notch that forms a gap between it and the first circuit board, and a second electrical connection point is provided in a part of the gap formed by the second notch portion so as to be in contact with the housing base and the first circuit board. The electronic control device according to claim 11.

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