Electronic control device

Abstract

This electronic control device comprises a circuit board, a tall heat-producing component mounted on the circuit board, and a housing for accommodating the circuit board. The tall heat-producing component is disposed at an edge part of the circuit board. The housing has placement parts which are provided at both ends of the tall heat-producing component along the edge part of the circuit board, and which abut on fixing parts of the circuit board or on the circuit board. The placement parts are disposed around the tall heat-producing component so as to surround the central part side of the circuit board. Accordingly, it is possible, in an electronic control device that has a tall heat-producing component disposed at an edge part of a substrate of an electronic component, to reduce influence of vibration and of mechanical impact, and also to reduce the amount of heat, which is generated by the tall heat-producing component, to be transmitted to a low rated-temperature component.

Description

Electronic control unit

[0001] The present disclosure relates to electronic control devices.

[0002] Electronic control devices installed in the engine compartment are subject to many requirements, including waterproofing, heat resistance, corrosion resistance, vibration resistance, resistance to mechanical shock (shock resistance), and EMC (Electromagnetic Compatibility). Products also need to have a long life. Furthermore, they need to be able to operate even in harsh operating environments. Furthermore, while electronic control devices are becoming larger with the increasing sophistication and integration of functions in vehicles, there is a demand for inexpensive, high-quality products.

[0003] Among the various requirements mentioned above, there is also a need to ensure a degree of freedom in the layout and pattern design of components on the board.

[0004] Patent document 1 discloses an electronic control device in which computing elements, heat generating elements, etc. are provided on the mounting surface of a board fixed to a case, with the aim of improving heat dissipation from heat generating elements and suppressing vibration of the board, and a heat dissipation section is provided in contact with the back side opposite the mounting surface of the board at a position corresponding to the heat generating area, and the electronic control device has a plurality of first fixing sections that fix the board to the case along the outer peripheral edge of the board, and a second fixing section that is located closer to the center of the board than the first fixing sections and at the boundary between the heat generating area and the control area.

[0005] JP 2015-178330 A

[0006] As electronic control devices become larger, they are subjected to greater vibrations, so measures to improve vibration resistance are necessary. Similar measures are also required for shock resistance.

[0007] Furthermore, since high-heat-generating components and low-temperature-rated components are placed on the same board, there is a problem that the heat generated by the high-heat-generating components is transferred to the low-temperature-rated components via the board. To solve this problem, it is necessary to arrange the high-heat-generating components and low-temperature-rated components in a way that thermally separates them.

[0008] The electronic control device disclosed in Patent Document 1 does not take into consideration the problem that may arise when the heating element is tall.

[0009] The object of the present disclosure is to reduce the effects of vibration and mechanical shock in an electronic control device in which tall heat-generating components are arranged at the edge of a board, and to reduce the amount of heat generated by the tall heat-generating components that is transferred to low-rated temperature components.

[0010] The electronic control device of the present disclosure comprises a circuit board, a tall heat-generating component mounted on the circuit board, and a housing that houses the circuit board, wherein the tall heat-generating component is arranged on the edge portion of the circuit board, and the housing has a fixing portion for the circuit board or a mounting portion that abuts against the circuit board, which is provided at both ends along the edge portion of the circuit board of the tall heat-generating component, and the mounting portion is arranged around the tall heat-generating component so as to surround the central side of the circuit board.

[0011] According to the present disclosure, in an electronic control device in which tall heat-generating components are arranged on the edge of a board, the effects of vibration and mechanical shock can be reduced, and the amount of heat generated by the tall heat-generating components that is transferred to low-rated temperature components can be reduced. Other problems, configurations, and effects will become clear from the description of the following embodiments.

[0012] FIG. 1 is an exploded perspective view showing an electronic control device according to a first embodiment; FIG. 2 is a cross-sectional view showing a flange portion of the electronic control device according to the first embodiment; FIG. 3 is a top view showing the electronic control device according to the first embodiment; FIG. 4 is a top view showing a circuit board of the electronic control device according to the first embodiment; FIG. 5 is a plan view showing a mounting portion of the electronic control device according to the first embodiment; FIG. 6 is a cross-sectional view of a main part showing a screw fixing portion of the electronic control device according to the first embodiment; FIG. 7 is a cross-sectional view of a main part showing a heat dissipation adhesive and a pedestal of the electronic control device according to the first embodiment; FIG. 8 is a cross-sectional view of a main part showing an adhesive portion between the pedestal and the circuit board of the electronic control device according to the first embodiment; FIG. 9 is a cross-sectional view of an inductor of the electronic control device according to the first embodiment; FIG. 10 is a plan view showing a circuit board of the electronic control device according to the second embodiment; FIG. 11 is a plan view showing a circuit board of the electronic control device according to the third embodiment;

[0013] The electronic control unit is larger than conventional units, measuring approximately 250 mm x 230 mm, and weighing approximately 1.8 kg. The electronic control unit is installed in the engine compartment of the vehicle via brackets, but there are only a few locations where the electronic control unit is fixed by the brackets, and the electronic control unit is subjected to very large vibrations and shocks while the vehicle is in operation.

[0014] Furthermore, since high-heat-generating components and low-temperature-rated components are placed on the same board, there is a problem that the heat generated by the high-heat-generating components is transferred to the low-temperature-rated components via the board. To solve this problem, it is possible to attach a heat sink to the high-heat-generating components themselves or between the high-heat-generating components and the low-temperature-rated components. Here, a high-heat-generating component refers to a component placed on the board that generates a relatively large amount of heat. A low-temperature-rated component refers to a component placed on the board that can tolerate a relatively low temperature.

[0015] The configuration and effects of an electronic control device according to an embodiment of the present disclosure will be described below with reference to the drawings. The electronic control device controls, for example, an engine, a transmission, etc. Note that the same reference numerals in each drawing indicate the same parts.

[0016] 1 is an exploded perspective view showing an electronic control device according to a first embodiment. Note that, for clarity of the drawing, some of the electronic components mounted on a board are omitted.

[0017] 1, the electronic control device 1 mainly includes a circuit board 3, a first housing 2, a second housing 4, a sealing material 5, and three connectors 6. The first housing 2 and the second housing 4 are collectively referred to as simply the "housing."

[0018] Electronic components and the like are mounted on the circuit board 3. The circuit board 3 is disposed between the first housing 2 and the second housing 4. The first housing 2 has at least three openings through which connectors 6 are inserted. A sealant 5 is sandwiched between the peripheral edge of the first housing 2 and the peripheral edge of the second housing 4, thereby waterproofing the space formed between the first housing 2 and the second housing 4. A connector sealant 5a is sandwiched between the inserted connector 6 and the peripheral edge of the opening of the first housing 2, thereby eliminating any gaps between the connector 6 and the first housing 2 and ensuring waterproofing. In this way, the circuit board 3 is protected by the first housing 2 and the second housing 4. The sealant 5 and the connector sealant 5a also prevent the intrusion of foreign matter.

[0019] The connector 6 is electrically connected to the circuit board 3. The circuit board 3 is fixed to the first housing 2 by a board fixing screw 81. The second housing 4 is fixed to the first housing 2 by a housing fixing screw 82.

[0020] An inductor 21 is disposed near one side of the substantially rectangular edge of the circuit board 3. A heat dissipating adhesive 7 is disposed at a predetermined position on the edge of the circuit board 3. The heat dissipating adhesive 7 is disposed so as to adhere closely to a pedestal (not shown) disposed on the underside of the first housing 2. In other words, the heat dissipating adhesive 7 is interposed between the pedestal and the circuit board 3, and the circuit board 3 and the pedestal are fixed via the heat dissipating adhesive 7. The pedestal is indicated by the reference numerals 11, 12, and 13 in FIG. 7 and other figures, which will be described later.

[0021] Note that the "edge portion" refers to the peripheral portion of the circuit board 3, i.e., the portion close to the edge (side) of the circuit board 3 when viewed from the center of the circuit board 3, regardless of the shape of the circuit board 3.

[0022] The first housing 2, together with the second housing 4, houses the circuit board 3 therein and protects the circuit board 3, on which electronic components are mounted, from water, foreign matter, etc. From the viewpoints of dissipating heat generated by the electronic components and shielding noise, the first housing 2 and the second housing 4 are preferably made of metal, with lightweight and low-cost aluminum being preferred. The first housing 2 and the second housing 4 are manufactured by aluminum die-casting using a mold.

[0023] In the case of the electronic control device 1 that is configured with electronic components that do not require heat dissipation or shielding, the first housing 2 and the second housing 4 may be made of resin. In the case of resin, the first housing 2 and the second housing 4 are manufactured by injection molding.

[0024] The electronic control device 1 shown in FIG. 1 is an example, but its external dimensions are 250 mm x 230 mm, which is relatively large among electronic control devices arranged in an engine room, and the shape of its top surface is approximately rectangular.

[0025] FIG. 2 is a cross-sectional view showing a flange portion of the electronic control unit according to this embodiment.

[0026] As shown in the figure, the first housing 2 has a flange portion 22 and a first housing protrusion 111. Meanwhile, a first groove 41 is provided on the outer periphery of the second housing 4. The first housing protrusion 111 is provided at a position corresponding to the first groove 41. A sealant 5 is filled between the first groove 41 and the first housing protrusion 111, and the first housing 2 and the second housing 4 are fixed together with the first housing protrusion 111 buried in the sealant 5. By sealing with the sealant 5, electronic components on the circuit board 3 installed inside the first housing 2 and the second housing 4 can be protected from foreign matter such as salt water.

[0027] The first groove 41 of the first housing 2 is provided around the outer periphery of the first housing 2, providing a completely sealed structure. In addition, assuming mounting to a vehicle using a bracket, a second groove 42 is provided outside the first groove 41 to prevent the sealing material 5 from leaking out.

[0028] The first housing 2 and the second housing 4 are configured to be in physical contact with each other at screw fastening portions or flange portions to transfer heat. The material of the second housing 4 is preferably a metal, and aluminum is preferable. The second housing 4 is preferably formed by aluminum die-casting using a mold.

[0029] A silicone adhesive is suitable for the sealant 5. In particular, the electronic control unit 1 is expected to be installed in the engine compartment and has a completely sealed structure. Therefore, pressure changes and thermal expansion occur due to temperature changes inside the electronic control unit 1, causing the centers of the first housing 2 and the second housing 4 to bend outward. As a result, the centers of the long sides of the first housing 2 and the second housing 4 deform the most. The sealant 5 used should have adhesive strength that can withstand such deformation. Note that the sealant 5 generates outgassing when hardened, and this gas must be vented to the outside of the electronic control unit 1.

[0030] The electronic control device 1 of this embodiment is approximately twice as large as conventional electronic control devices, so a metal material is selected for the second housing 4, and a thickness that prevents plastic deformation is used to ensure strength. The circuit board 3 is also approximately twice as large as the circuit boards mounted on conventional electronic control devices, measuring 196 mm x 213 mm. Furthermore, with its increased functionality, it is equipped with three connectors 6 and has approximately 300 terminals. Furthermore, the circuit board 3 has eight layers, which results in a higher heat generation per volume compared to conventional six-layer circuit boards.

[0031] FIG. 3 is a top view showing the electronic control device according to this embodiment.

[0032] This figure shows the first housing 2 of the electronic control device. The dimensions of the first housing 2 are 250 mm (L1) × 230 mm (L2), and a flange portion 22 is provided around the entire periphery of the edge portion. The flange portion 22 is provided with a bracket mounting surface 31 or 32. A bracket (not shown) is attached to one of the bracket mounting surfaces 31, 32, i.e., two opposing edges of the edge portion of the flange portion 22, and the electronic control device is fixed by the bracket. Note that the bracket may be configured so as not to come into contact with the bottom surface of the second housing 4.

[0033] Therefore, the brackets are used to secure the electronic control unit to the brackets, with beams supported at both ends with a distance of 250 mm (L1) or 230 mm (L2). This is a severe configuration in which vibrations and mechanical shocks applied to the electronic control unit have a significant impact on the circuit board installed inside the electronic control unit.

[0034] FIG. 4 is a top view showing the circuit board of the electronic control device according to this embodiment.

[0035] The top surface of the circuit board 3 shown in this figure is the surface facing the first housing 2 (see FIG. 1). Inductors 21a, 21b, 21c, 21d, and 21e, which are tall heat-generating components, are arranged in a straight line along the edge of the circuit board 3. First and second fixing holes 51 and 52 are provided at both ends of the linearly arranged inductors 21a, 21b, 21c, 21d, and 21e, allowing the first housing 2 and the circuit board 3 to be fixed with screws. Heat-dissipating adhesives 7a, 7b, 7c, 7d, 7e, and 7f are arranged between the inductors 21a, 21b, 21c, 21d, and 21e arranged along the edge of the circuit board 3 and the central portion of the circuit board 3, adjacent to the inductors 21a, 21b, 21c, 21d, and 21e. The heat dissipation adhesives 7a, 7b, 7c, 7d, 7e, and 7f are configured to contact a pedestal (not shown) arranged on the underside of the first housing 2. Here, the tall heat-generating components refer to electronic components that make up the circuit board 3 and that are relatively tall and generate a large amount of heat.

[0036] With this configuration, heat generated in inductors 21a, 21b, 21c, 21d, and 21e is transferred to first housing 2 via heat dissipation adhesives 7a, 7b, 7c, 7d, 7e, and 7f and the pedestal, and heat transfer from inductors 21a, 21b, 21c, 21d, and 21e to the center side of circuit board 3 is suppressed. This prevents electronic components on circuit board 3 from reaching a temperature higher than the rated temperature, and suppresses deformation of circuit board 3 due to thermal expansion.

[0037] Here, a tall heat-generating component refers to a tall component that generates a large amount of heat. A tall component refers to a component that is taller than an integrated circuit (IC) or other component. A tall component has a resonance frequency of 2000 Hz or less as a standalone electronic component, making it vulnerable to vibration and mechanical shock. The standard for vibration resistance required of electronic control devices is random vibration of 10 Hz to 2000 Hz. The standard for impact resistance is 25 G, 800 times per axis, for a total of 2300 times. Both are extremely harsh.

[0038] Furthermore, a high heat generating component refers to a component that generates a large amount of heat among the electronic components arranged on the circuit board 3. If a high heat generating component is arranged near a low temperature rated component, the heat from the high heat generating component will be transferred to the low temperature rated component, causing the temperature of the low temperature rated component to exceed the rated temperature, which may cause the low temperature rated component to stop functioning.

[0039] In the case of the circuit board 3 of the electronic control device shown in the figure, the electronic components that generate the most heat are the inductors 21a, 21b, 21c, 21d, and 21e, and if the heat is not removed, the inductors may heat up to around the rated temperature of 175°C. The inductors 21a, 21b, 21c, 21d, and 21e are also tall components.

[0040] When arranging multiple high heat generating components, if they are arranged in multiple rows or a square rather than in a straight line, the heat from the high heat generating components is less likely to be released to the outside and is more likely to accumulate, which may result in the rated temperature being exceeded. For this reason, arranging them in a straight line is preferable.

[0041] FIG. 5 is a plan view showing a mounting portion for the electronic control unit according to this embodiment.

[0042] In the figure, mounting portions 11a, 11b, 12a, 12b, and 13a provided on the first housing 2 are arranged between the inductors 21a, 21b, 21c, 21d, and 21e arranged on the edge portions of the circuit board 3 and the central portion of the circuit board 3, adjacent to the inductors 21a, 21b, 21c, 21d, and 21e. The mounting portions 11a, 11b, 12a, 12b, and 13a are fixed to the circuit board 3 via heat dissipation adhesives 7a, 7b, 7c, 7d, 7e, and 7f. Furthermore, mounting portions 51a and 52a provided on the first housing 2 are arranged at both ends of the linearly arranged inductors 21a, 21b, 21c, 21d, and 21e. The mounting portions 51a and 52a are fixed to the circuit board 3 with screws.

[0043] The mounting portions 11a, 11b, 12a, 12b, 13a, 51a, and 52a are columnar portions extending from the housing (first housing 2) toward the circuit board 3.

[0044] With this configuration, the amount of deformation of the circuit board 3 can be reduced by approximately 72% compared to a configuration having only the screw mounting portions 51a, 52a. As a result, vibration resistance and shock resistance can be imparted to components such as the inductors 21a, 21b, 21c, 21d, and 21e, which are disposed on the edges of the circuit board 3 and are vulnerable to vibration and mechanical shock, without the need to provide additional earthquake-resistant bases or the like.

[0045] However, if the entire periphery of the inductors 21a, 21b, 21c, 21d, and 21e is surrounded by mounting portions without any gaps, it is not possible to form a wiring pattern (hereinafter simply referred to as a "pattern") on the surface of the circuit board 3 on which the inductors 21a, 21b, 21c, 21d, and 21e are mounted. Furthermore, if a pattern is formed to avoid mounting portions without gaps, the path of the pattern becomes longer, resulting in higher impedance. Therefore, in consideration of the degree of freedom in pattern design, the mounting portions provided around the inductors 21a, 21b, 21c, 21d, and 21e must have at least one gap to allow the pattern from the inductors 21a, 21b, 21c, 21d, and 21e to pass through. In this case, it is desirable to provide gaps in multiple locations so that the pattern can sufficiently reduce impedance.

[0046] FIG. 6 is a cross-sectional view of a main part showing a screw fixing portion of the electronic control unit according to this embodiment.

[0047] This figure shows cross sections of inductors 21a, 21b, 21c, 21d, and 21e arranged on the upper surface of the circuit board 3. A first screw boss 53 and a second screw boss 54 are provided on the lower surface of the first housing 2. The circuit board 3 is arranged between the first housing 2 and the second housing 4. Screws 81 pass through the first fixing holes 51 and the second fixing holes 52 (see FIG. 4) of the circuit board 3 and are screwed into the first screw boss 53 and the second screw boss 54. In this way, the circuit board 3 is fixed to the first housing 2. Note that the screw 81 to be screwed may be a tapping screw.

[0048] FIG. 7 is a cross-sectional view of a main part showing a heat dissipation adhesive and a pedestal of the electronic control device according to this embodiment.

[0049] This figure shows a cross section of pedestals 11, 12, and 13 (mounting portions) provided on the underside of the first housing 2. Heat dissipation adhesives 7a, 7b, 7c, 7d, 7e, and 7f are provided on the upper surface of the circuit board 3. The heat dissipation adhesives 7a, 7b, 7c, 7d, 7e, and 7f are fixed to the pedestals 11, 12, and 13 by adhesive. Note that, in consideration of castability, the three pedestals 11, 12, and 13 may be integrated without providing steps between them, or additional steps may be provided to reduce material.

[0050] FIG. 8 is a cross-sectional view of a main part showing the adhesive portion between the pedestal and the circuit board of the electronic control unit according to this embodiment.

[0051] In this figure, a heat dissipating adhesive 7 is sandwiched between the pedestal 11 and the circuit board 3, thereby fixing the first housing 2 and the circuit board 3 together. The thickness D of the heat dissipating adhesive 7 must be approximately 0.3 mm, taking into account distortion and assembly tolerances of the circuit board 3 and the first housing 2. It is preferable to minimize the gap D between the pedestal 11 and the circuit board 3 to reduce thermal resistance, but it must be at least 0.2 mm to ensure sufficient strength of the heat dissipating adhesive 7. Furthermore, it is preferable to machine the bonding surface between the pedestal 11 and the heat dissipating adhesive 7 to ensure dimensional accuracy. However, by setting the gap between the pedestal 11 and the circuit board 3 to 0.3 mm or more, machining costs can be reduced.

[0052] Here, the heat dissipating adhesive 7 is applied to a thickness equal to or greater than the gap between the circuit board 3 and the first housing 2 in order to reliably connect the circuit board 3 and the first housing 2. Furthermore, if it takes a long time from the application of the heat dissipating adhesive 7 to the assembly with the first housing 2, the height of the heat dissipating adhesive 7 may become too low, potentially making it impossible to connect with the pedestal 11. For this reason, it is necessary to select a heat dissipating adhesive 7 that has high thixotropy. The thixotropy of the heat dissipating adhesive 7 is preferably 2.6 Pa·s or more.

[0053] FIG. 9 is a cross-sectional view showing an inductor of the electronic control device according to this embodiment.

[0054] The inductor 21 shown in this figure has a package 91 and a terminal 92. The terminal 92 and the circuit board 3 are joined and electrically connected by solder 101. The inductor 21 is preferably disposed on the upper surface of the circuit board 3.

[0055] In the solder reflow process, after the upper surface of the circuit board 3 is reflowed, the circuit board 3 is flipped over so that the lower surface faces up, and reflow is performed again. To prevent the inductor 21 fixed by solder to the upper surface of the circuit board 3 from falling during the lower surface reflow, a fall prevention adhesive 102 is provided between the inductor 21 and the circuit board 3. A material that thermally hardens during the upper surface reflow is selected for the fall prevention adhesive 102. Furthermore, to prevent the inductor 21 from falling during the lower surface reflow, the fall prevention adhesive 102 must be bonded over a sufficient area. This area depends on the weight of the inductor 21. The fall prevention adhesive 102 is cheaper than the heat dissipation adhesive 7, and the amount required to be applied is smaller.

[0056] When the dimensions of the circuit board are large, the edge portions of the circuit board 3 are susceptible to vibration and mechanical shock, and are prone to large deformation.

[0057] In the circuit board 3 of this embodiment, the inductor 21, which is a tall component that is vulnerable to vibration and mechanical shock, is arranged in a straight line at its edge, and the periphery is supported by mounting portions 11a, 11b, 12a, 12b, 13a, 51a, and 52a, thereby reducing the effects of vibration and mechanical shock and suppressing deformation.

[0058] Furthermore, by thermally connecting the circuit board 3 and the pedestal 11 via the heat dissipation adhesive 7, heat generated from the inductors 21a, 21b, 21c, 21d, and 21e arranged on the edges of the circuit board 3 is transferred to the pedestals 11, 12, and 13 via the heat dissipation adhesive 7 as it diffuses toward the center of the circuit board 3, and is ultimately removed by heat transfer with the outside air and heat radiation from the outer surface of the first housing 2. This reduces the heat transferred to low-rated temperature components arranged in the center of the circuit board 3, preventing the low-rated temperature components from becoming too hot and losing their functionality.

[0059] FIG. 10 is a plan view illustrating a circuit board of an electronic control device according to the second embodiment.

[0060] In this figure, inductors 21a, 21b, 21c, 21d, and 21e are linearly arranged on the edge of circuit board 3, and heat dissipation adhesive 7g is arranged on both ends of the linearly arranged inductors 21a, 21b, 21c, 21d, and 21e and on the central side of circuit board 3. The pedestal is fixed to circuit board 3 via heat dissipation adhesive 7g. Heat dissipation adhesive 7g has a continuous shape without any gaps and is arranged in a U-shape to surround inductors 21a, 21b, 21c, 21d, and 21e. In this case, the patterns provided on the central side of circuit board 3 from inductors 21a, 21b, 21c, 21d, and 21e must be arranged to bypass the surface of circuit board 3 on which inductors 21a, 21b, 21c, 21d, and 21e are arranged. In order to connect the pedestal and the circuit board 3 with sufficient strength, it is preferable to select a heat dissipating adhesive 7g having a Young's modulus of 20 GPa or more or a tensile shear strength of 0.25 MPa or more.

[0061] The other configurations are the same as those of the electronic control unit 1 of the first embodiment.

[0062] According to this embodiment, there is no need to use screws to fasten the circuit board 3, which enables a reduction in cycle time and cost. Furthermore, by providing the heat dissipation adhesive 7g continuously without any gaps and fastening it to the pedestal, it is possible to more effectively suppress vibrations at the edge portions of the circuit board 3. Furthermore, since heat generated from the inductors 21a, 21b, 21c, 21d, and 21e can be more effectively dissipated to the first housing 2 via the heat dissipation adhesive 7g, it is possible to reduce the propagation of heat to low-rated temperature components arranged around the inductors 21a, 21b, 21c, 21d, and 21e.

[0063] FIG. 11 is a plan view illustrating a circuit board of an electronic control device according to a third embodiment.

[0064] In this figure, electrolytic capacitors 61 and 62 are arranged near inductors 21a, 21b, 21c, 21d, and 21e that are arranged in a straight line on an edge portion of circuit board 3. Electrolytic capacitors 61 and 62 are electrically connected to inductor 21e by pattern 121.

[0065] In order to reduce impedance, it is not desirable to place electrolytic capacitors 61 and 62 at positions far away from inductor 21e. On the other hand, inductors 21a, 21b, 21c, 21d, and 21e are the components that generate the most heat among the electronic components arranged on circuit board 3, and can generate heat up to approximately 175°C.

[0066] Although the heat generation of the electrolytic capacitors 61 and 62 themselves is not large, in order to ensure a long life, it is necessary to keep the temperature of the electrolytic capacitors 61 and 62 below 135°C, which is the rated temperature of the electrolytic capacitors 61 and 62, and it is therefore necessary to suppress heat transfer from the inductors 21a, 21b, 21c, 21d, and 21e.

[0067] Therefore, heat dissipation adhesives 7a, 7b, 7c, 7d, 7e, and 7f are placed between the inductors 21a, 21b, 21c, 21d, and 21e and the electrolytic capacitors 61 and 62, providing contact points between the pedestal and the circuit board 3.

[0068] The other configurations are the same as those of the electronic control unit 1 of the first embodiment.

[0069] According to this embodiment, it is possible to arrange the electrolytic capacitors 61 and 62, which have a low rated temperature and need to be arranged near the inductors 21a, 21b, 21c, 21d, and 21e, without applying a heat-dissipating adhesive to the upper surfaces of the inductors 21a, 21b, 21c, 21d, and 21e to facilitate heat dissipation from the upper surfaces of the inductors 21a, 21b, 21c, 21d, and 21e to the lower surface (inner surface) of the first housing 2. Furthermore, if a heat-dissipating adhesive is applied to the upper surfaces of the inductors 21a, 21b, 21c, 21d, and 21e, stress may be applied to the inductor solder due to differences in thermal expansion coefficients, which may cause solder cracks. However, because it is not necessary to apply a heat-dissipating adhesive, it is possible to prevent cracks from occurring in the inductor solder.

[0070] From the viewpoint of heat dissipation of the inductors 21a, 21b, 21c, 21d, and 21e, it is desirable to apply a heat dissipation adhesive to the upper surfaces of the inductors 21a, 21b, 21c, 21d, and 21e and the lower surface (inner surface) of the first housing 2, as long as the problem of solder cracks does not occur.

[0071] The effects of the present disclosure will be summarized below.

[0072] According to the present disclosure, it is possible to reduce the effects of vibration and mechanical shock at the edge of the board, and to prevent cracks in the solder joining electronic components placed at the edge of the board and breakage of the leads of the electronic components.

[0073] Furthermore, according to the present disclosure, by arranging high heat generating components at the edge of the board, it is possible to limit the direction of heat transmitted from the high heat generating components, thereby preventing low rated temperature components arranged around the high heat generating components from being exposed to the heat from the high heat generating components, thereby preventing their functionality from being reduced and their lifespan from being shortened.

[0074] 1: Electronic control device, 2: First housing, 3: Circuit board, 4: Second housing, 5: Sealing material, 5a: Connector sealing material, 6: Connector, 7, 7a, 7b, 7c, 7d, 7e, 7f, 7g: Heat dissipation adhesive material, 11, 12, 13: Pedestal, 11a, 11b, 12a, 12b, 13a: Mounting portion, 111: First housing protrusion, 21:, 21a, 21b, 21c, 21d, 21e: Inductor, 22: Flange portion, 31:, 32: bracket mounting surface, 41: first groove portion, 42: second groove portion, 51: first fixing hole, 52: second fixing hole, 51a, 52a: mounting portion, 53: first screw boss, 54: second screw boss, 61, 62: electrolytic capacitor, 81: board fixing screw, 82: housing fixing screw, 91: package, 92: terminal, 101: solder, 102: fall prevention adhesive, 121: pattern.

Claims

1. An electronic control device having a circuit board, a tall heat-generating component mounted on the circuit board, and a housing that houses the circuit board, wherein the tall heat-generating component is arranged on an edge portion of the circuit board, the housing has a fixing portion for the circuit board or a mounting portion that abuts the circuit board, the mounting portion being provided on both ends along the edge portion of the circuit board of the tall heat-generating component, and the mounting portion is arranged around the tall heat-generating component and surrounding the central side of the circuit board.

2. The electronic control device according to claim 1, characterized in that a plurality of said tall heat-generating components are arranged in a straight line on said edge portion of said circuit board, and said fixing portion is arranged at both ends of the row of said plurality of said tall heat-generating components.

3. The electronic control device according to claim 1, characterized in that the fixing portion is a screw fixing portion, and the mounting portion is a columnar portion extending from the housing toward the circuit board.

4. The electronic control device according to claim 1, further comprising a heat dissipating adhesive provided between said mounting portion and said circuit board.

5. The electronic control device according to claim 1, characterized in that a plurality of said mounting sections are provided.

6. An electronic control device as claimed in any one of claims 1 to 5, characterized in that a heat dissipating adhesive is provided between the upper surface of the tall heat-generating component and the inner surface of the housing.

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