JP7372810B2 - electronic control unit - Google Patents

Description

The present invention relates to an electronic control device that can be mounted on a vehicle.

As in-vehicle electronic control devices become more sophisticated, the amount of heat generated by electronic components is increasing. Furthermore, in automatic driving systems and the like, it is necessary to arrange electronic components close to each other due to the need for high-speed transmission between electronic components. Heat-generating electronic components are generally thermally connected to a heat-radiating block provided in a housing or the like via a heat-radiating member to radiate heat. Furthermore, from the perspective of reducing the weight of in-vehicle electronic control devices, development of in-vehicle electronic control devices using materials such as high heat conductive resin for the housing is progressing. In an in-vehicle electronic control device that uses the above materials for the housing, when multiple heat-generating electronic components are placed in close proximity, the heat generated by the heat-generating electronic components placed in the heat radiation block that radiates the heat from the heat-generating electronic components may be reduced. The temperature of each heat generating electronic component increases due to interference. In order to suppress thermal interference between heat-generating electronic components, Patent Document 1 proposes a structure in which a single hole is formed in a substrate to suppress thermal interference.

Japanese Patent Application Publication No. 2006-173243

In order to reduce weight, in-vehicle electronic control units use materials such as high heat conductive resin for their housings, but thermal interference occurs between heat-generating electronic components that are placed close to each other, so metal housings have been used. The temperature of electronic components will rise compared to when

Therefore, there is a need to suppress the temperature rise of heat-generating components due to thermal interference on the board on which electronic components are mounted. In order to suppress such a temperature rise, when the structure disclosed in Patent Document 1 is adopted, thermal interference is suppressed by a single hole, so wiring routes between electronic components may become impossible. This can cause problems in high-speed signal transmission between heat-generating electronic components.

The present invention has been made in view of the above circumstances, and its purpose is to provide an electronic control device that can suppress thermal interference between electronic components while suppressing an increase in wiring length between adjacent electronic components. There is a particular thing.

To achieve the above object, an electronic control device according to a first aspect includes: a circuit board on which a first electronic component and a second electronic component are mounted adjacent to each other; a casing for fixing the circuit board; The circuit board includes a low heat conduction part having a lower thermal conductivity than the circuit board, and the low heat conduction part is between a mounting area of the first electronic component and a mounting area of the second electronic component. are arranged discretely in the middle region of .

According to the present invention, it is possible to suppress thermal interference between electronic components while suppressing an increase in wiring length between adjacent electronic components.

FIG. 1 is an exploded perspective view showing the configuration of a vehicle-mounted electronic control device according to a first embodiment. FIG. 2 is an exploded perspective view showing the configuration of the in-vehicle electronic control device without the through hole 12c of FIG. 1. FIG. 3 is a cross-sectional view showing the configuration of the in-vehicle electronic control device of FIG. 1 cut at the positions of electronic components 11a and 11b. FIG. 4 is a plan view showing the configuration of a circuit board on which the electronic components 11a and 11b of FIG. 3 are mounted. FIG. 5 is a cross-sectional view showing the direction of heat propagation in the thermal interference path between the electronic components 11a and 11b shown in FIG. FIG. 6 is a plan view showing a heat dissipation path on a circuit board on which the electronic components 11a and 11b of FIG. 3 are mounted. FIG. 7 is a plan view showing the configuration of a circuit board applied to the in-vehicle electronic control device according to the second embodiment. FIG. 8 is a plan view showing the configuration of a circuit board applied to the in-vehicle electronic control device according to the third embodiment. FIG. 9 is a cross-sectional view showing the configuration around electronic components 11a and 11b applied to the in-vehicle electronic control device according to the fourth embodiment. FIG. 10 is a sectional view showing the configuration around electronic components 11a and 11b applied to the on-vehicle electronic control device according to the fifth embodiment. FIG. 11 is a cross-sectional view showing the configuration around electronic components 11a and 11b applied to the in-vehicle electronic control device according to the sixth embodiment. FIG. 12 is a cross-sectional view showing the configuration around the electronic component 11 applied to the in-vehicle electronic control device according to the first comparative example. FIG. 13 is a cross-sectional view showing the configuration around electronic components 11a and 11b applied to a vehicle-mounted electronic control device according to a second comparative example. FIG. 14 is a plan view showing the configuration of a circuit board on which electronic components 11a and 11b of FIG. 13 are mounted. FIG. 15 is a cross-sectional view showing the direction of heat propagation in the thermal interference path between the electronic components 11a and 11b in FIG. 13. FIG. 16 is a cross-sectional view showing the configuration around electronic components 11a and 11b applied to a vehicle-mounted electronic control device according to a third comparative example. FIG. 17 is a plan view showing the configuration of a circuit board on which electronic components 11a and 11b of FIG. 16 are mounted. FIG. 18 is a diagram showing a comparison of the temperatures of electronic components when metal and high heat conductive resin are used as casing materials for fixing a circuit board on which electronic components are individually mounted. FIG. 19 is a diagram illustrating a comparison of the temperatures of electronic components when metal and high heat conductive resin are used as casing materials for fixing circuit boards on which electronic components are mounted adjacent to each other. FIG. 20 is a diagram comparing and illustrating numerical examples of temperature increases in the first, second, and third embodiments and the first, second, and third comparative examples. FIGS. 21A to 21C are plan views showing other examples of intermediate regions between mounting regions of electronic components.

Embodiments will be described with reference to the drawings. The embodiments described below do not limit the claimed invention, and all of the elements and combinations thereof described in the embodiments are essential to the solution of the invention. Not necessarily.

In the following description, an on-vehicle electronic control device mounted on a vehicle will be taken as an example of the electronic control device.
FIG. 1 is an exploded perspective view showing the configuration of a vehicle-mounted electronic control device according to a first embodiment.
In FIG. 1 , an on-vehicle electronic control device 1 includes a circuit board 12 and a housing 10 . The housing 10 includes a base 13 and a cover 14.

Electronic components 11a to 11c are mounted on the circuit board 12. The electronic components 11a to 11c are, for example, heat generating electronic components such as semiconductor elements. The electronic components 11a to 11c can be mounted on the circuit board 12, for example, in the form of a package in which a semiconductor chip is sealed. This package is, for example, an SOP (Small Outline Package), a QFP (Quad Flat Package), or a BGA (Ball grid array).

Here, the electronic components 11a and 11b are mounted on the circuit board 12 adjacent to each other. Note that the electronic components 11a and 11b may have different calorific values. The electronic component 11a is, for example, a microcomputer, and the electronic component 11b is, for example, an ASIC (Application Specific Integrated Circuit).

On the circuit board 12, in addition to the electronic components 11a to 11c, passive components such as resistors and capacitors forming an electronic circuit are electrically connected to one or both sides of the circuit board 12 using a conductive connecting material such as solder. be done.

Further, a connector 15 is mounted on the circuit board 12. Connector 15 electrically connects circuit board 12 and the outside. Connector 15 may be placed at the end of circuit board 12 . A required number of pin terminals 15a are inserted into the main body of the connector 15 by press-fitting or the like. The connector 15 is electrically connected to the circuit board 12 by soldering or press-fitting the pin terminals 15a to the circuit board 12.

The circuit board 12 includes N (N is an integer of 2 or more) through holes 12c. The N through holes 12c are arranged in an intermediate region RM1 between the mounting region of the electronic component 11a and the mounting region of the electronic component 11b. At this time, the N through holes 12 can be arranged at positions that do not protrude from the intermediate region RM1. The planar shape of the through hole 12c is not necessarily limited to a round shape, and may be elliptical, rectangular, or polygonal.

The N through-holes 12c can be used as a low thermal conductivity portion having a lower thermal conductivity than the circuit board 12. At this time, the low thermal conductivity portions are discretely arranged in the intermediate region RM1 between the mounting region of the electronic component 11a and the mounting region of the electronic component 11b. Here, the N through holes 12c can be arranged at positions where the temperature decreasing effect due to suppression of thermal interference between the electronic components 11a and 11b exceeds the temperature increasing effect due to a decrease in heat dissipation of the circuit board 12. At this time, the N through holes 12c can be arranged so that the temperature of the electronic components 11a and 11b is 150° C. or lower.

The through hole 12c may be formed by punching, drilling, laser processing, chemical etching, or the like alone, or a combination of these methods. Note that as long as the through hole 12c is formed in the circuit board 12, the formation method is not limited to the above method.

Further, the circuit board 12 includes a screw hole 12d. A screw 22, which is an example of a fastening member, can be inserted into the screw hole 12d. The screw holes 12d can be arranged at the four corners of the circuit board 12.

The circuit board 12 may be, for example, a laminated wiring board made of thermosetting resin, glass cloth, and metal wiring on which a circuit pattern is formed, a board made of ceramics and metal wiring, or a flexible board made of polyimide or the like.

The housing 10 fixes the circuit board 12. At this time, the circuit board 12 is fixed to the base 13. The base 13 includes a frame member 13a that supports the circuit board 12 on the base 13. Pedestals 13b are provided at the four corners of the frame member 13a. The base 13 has a generally rectangular flat plate shape as a whole so as to close the lower opening of the cover 14 . A screw hole 13d is provided in the base 13 and the pedestal portion 13b.

Furthermore, a rectangular convex portion 21 is provided on the base 13. The rectangular convex portion 21 is arranged so as to be located below the electronic components 11a and 11b when the circuit board 12 is assembled into the housing 10. The rectangular convex portion 21 comes into contact with or comes close to the circuit board 12 when the circuit board 12 is assembled into the housing 10, and can improve heat dissipation of the electronic components 11a and 11b. At this time, the frame member 13a supports the circuit board 12 on the base 13 so that the circuit board 12 contacts or approaches the rectangular convex portion 21.

Cover 14 protects circuit board 12 from impacts, dust, and the like. The cover 14 has a box-like or lid-like shape with an open bottom and is assembled to the base 13 so as to cover the circuit board 12 .

The base 13 and the cover 14 are assembled by sandwiching the circuit board 12 to which the connector 15 is attached, thereby forming a box-type vehicle-mounted electronic control device. For example, the circuit board 12 is fixed to the housing 10 by being held between the pedestal portion 13d and the cover 14 and being screwed into the cover 14 with the screws 22 inserted into the screw holes 13d and 12d. Ru.

The structure for fixing the cover 14 and the base 13 in combination is not limited to the structure in which they are screwed together using the screws 22. For example, a structure may be adopted in which an assembly hole provided in an upright portion rising from the base 13 and a protrusion provided in the cover 14 are fitted and fixed together or fixed by adhesive.

The base 13 is manufactured by casting, pressing, cutting, injection molding, or the like using a resin composite material. The thermal conductivity of the resin composite material is preferably 30 W/m·K or less.

The cover 14 is manufactured by casting, pressing, cutting, injection molding, or the like using a metal material or a resin composite material. For example, for metal materials, materials obtained by casting or rolling alloys whose main components are aluminum, magnesium, iron, etc. can be used, and for resin composite materials, materials consisting of resin and filler can be used. can.

This resin composite material is, for example, at least one kind selected from thermoplastic resins such as polybutylene terephthalate, polyamide, polyethylene terephthalate, or polyphenylene sulfide, or thermosetting resins such as epoxy resins, phenolic resins, polyimide resins, or unsaturated polyester resins. A mixture of the above resin and at least one of glass fiber, inorganic filler such as silica or alumina, or metal powder is molded using injection molding, compression molding, transfer molding, or the like.

This resin composite material can be used as a high heat conductive resin. Here, by using a resin composite material made of resin and filler for the base 13 and the cover 14, it is possible to reduce the weight of the in-vehicle electronic control device 1.

Further, by providing N through holes 12c in the circuit board 12, it becomes possible to arrange the through holes 12c at intervals. Therefore, it is possible to secure an area on the circuit board 12 for wiring between the electronic components 11a and 11b without having to bypass the through hole 12c, and it is also possible to provide wiring between the electronic components 11a and 11b in the horizontal direction on the circuit board 12. Can block heat. As a result, it is possible to reduce thermal interference between the electronic components 11a and 11b, to suppress the temperature rise of the electronic components 11a and 11b, and to suppress an increase in the wiring length of the wiring between the electronic components 11a and 11b. This makes it possible to achieve high-speed signal transmission between the electronic components 11a and 11b.

FIG. 2 is an exploded perspective view showing the configuration of the in-vehicle electronic control device without the through hole 12c of FIG. 1.
In FIG. 2, the in-vehicle electronic control device 2 includes a circuit board 20 instead of the circuit board 12 in FIG. In the circuit board 20, the through hole 12c shown in FIG. 1 has been removed. The rest of the configuration of the vehicle-mounted electronic control device 2 is similar to the configuration of the vehicle-mounted electronic control device 1 shown in FIG.

When the circuit board 20 is used, since the through hole 12c of FIG. 1 is not provided, heat is more easily transmitted horizontally through the circuit board 12 between the electronic components 11a and 11b than when the circuit board 12 is used. Therefore, when the circuit board 20 is used, thermal interference between the electronic components 11a and 11b increases, and the temperature rise of the electronic components 11a and 11b increases, compared to when the circuit board 12 is used.

FIG. 3 is a cross-sectional view showing the configuration of the in-vehicle electronic control device of FIG. 1 cut at the positions of electronic components 11a and 11b.
In FIG. 3, the circuit board 12 includes thermal vias 12a and 12b in addition to the configuration shown in FIG. Thermal vias 12a and 12b radiate heat generated in each electronic component 11a and 11b through the circuit board 12 in the vertical direction. A filler may be embedded in the thermal vias 12a and 12b to improve heat dissipation. Thermal vias 12a and 12b are arranged directly below each electronic component 11a and 11b. Further, the thermal vias 12a and 12b are arranged so as to be directly above the rectangular convex portion 21 when the circuit board 12 is assembled to the housing 10.

Each electronic component 11a, 11b includes a terminal 17a, 17b. Each electronic component 11a, 11b is electrically connected to the circuit board 12 by soldering the terminals 17a, 17b to the circuit board 12.

Heat radiating members 18a, 18b are provided between each electronic component 11a, 11b and the circuit board 12. Heat radiating members 19a and 19b are provided between the rectangular convex portion 21 and the circuit board 12, corresponding to each electronic component 11a and 11b.

The heat radiating members 18a, 18b, 19a, and 19b radiate the heat generated in each electronic component 11a, 11b to the rectangular convex portion 21 through thermal contact. Furthermore, the heat dissipation members 18a and 18b relieve stress applied to the circuit board 12 due to differences in thermal expansion coefficients between the electronic components 11a and 11b and the circuit board 12.

The heat dissipation member 20 is preferably a sheet-like material containing adhesive, grease, a thermoplastic resin and a highly thermally conductive filler, or a sheet-like material containing a highly thermosetting resin such as a silicone resin or an epoxy resin and a thermally conductive filler. It is. The highly thermally conductive filler is, for example, metal, alumina or carbon.

FIG. 4 is a plan view showing the configuration of a circuit board on which the electronic components 11a and 11b of FIG. 3 are mounted.
In FIG. 4, the circuit board 12 includes wiring 16a that electrically connects the electronic components 11a and 11b. Here, when connecting the terminals 17a and 17b on opposite sides with the intermediate region RM1 in between, the wiring 16a can be arranged in the intermediate region RM1 so as to avoid the position of the through hole 12c. At this time, the wiring 16a can be arranged between the through holes 12c or at a position adjacent to the through holes 12c in the intermediate region RM1. In this case, the through holes 12c can be arranged on both sides of the wiring 16a.

For example, the through holes 12c can be arranged in M (M is a positive integer) rows so that each row is lined up in a straight line. FIG. 4 shows an example in which two through holes 12c are arranged in four rows so that each row is lined up in a straight line. At this time, the wiring 16a can linearly connect the terminals 17a and 17b on opposite sides with the intermediate region RM1 in between. Therefore, the terminals 17a and 17b can be connected through the shortest path, and high-speed signal transmission between the terminals 17a and 17b can be realized.

Furthermore, the through hole 12c occupies an area that enables wiring in the intermediate region RM1 and suppresses thermal interference between the electronic components 11a and 11b. At this time, the through hole 12c can occupy an area of 10% or more and 90% or less of the intermediate region RM1. Therefore, even when a resin composite material is used as the material for the housing 10, it is possible to suppress the temperature rise of the electronic components 11a and 11b while achieving high-speed signal transmission between the electronic components 11a and 11b. .

Note that among the opposing sides of the electronic components 11a and 11b, if both ends of the electronic component 11a side are points A and B, and both ends of the electronic component 11ab side are points C and D, the intermediate region RM1 is the point A, It is set within the area surrounded by B, C, and D.

FIG. 5 is a cross-sectional view showing the direction of heat propagation in the thermal interference path between the electronic components 11a and 11b shown in FIG.
In FIG. 5, heat Ha and Hb transmitted horizontally through the circuit board 12 between the electronic components 11a and 11b are blocked by the through hole 12c. Therefore, thermal interference between the electronic components 11a and 11b can be reduced, and a rise in temperature of the electronic components 11a and 11b can be suppressed.

FIG. 6 is a plan view showing a heat dissipation path on a circuit board on which the electronic components 11a and 11b of FIG. 3 are mounted.
In FIG. 6, the through hole 12c can be arranged at a position where heat dissipation outside the intermediate region RM1 is not reduced and thermal interference between the electronic components 11a and 11b can be suppressed. At this time, the through hole 12c can be arranged at a position that does not protrude from the intermediate region RM1 between the mounting region of the electronic component 11a and the mounting region of the electronic component 11b. This can prevent the heat dissipation paths ka and kb of the heat generated from each electronic component 11a and 11b from being cut off by the through hole 12c, and ensure the heat dissipation performance of the heat generated from each electronic component 11a and 11b. At the same time, thermal interference between the electronic components 11a and 11b can be reduced.

FIG. 7 is a plan view showing the configuration of a circuit board applied to the in-vehicle electronic control device according to the second embodiment.
In FIG. 7, the circuit board 32 includes a through hole 32c and a wiring 16b instead of the through hole 12c and wiring 16a of the circuit board 12 in FIG. The wiring 16b includes a bent portion. The bending portion can bend the wiring 16b so that the wiring 16b is not folded back. At this time, the through hole 32c can be arranged on the circuit board 32 along the wiring 16b so as to avoid the position of the wiring 16b.

As a result, even when the terminals 17a and 17b on opposite sides with the middle region RM1 in between do not face each other, the increase in the wiring length between the terminals 17a and 17b can be suppressed, and the distance between the electronic components 11a and 11b can be reduced. thermal interference can be reduced.

FIG. 8 is a plan view showing the configuration of a circuit board applied to the in-vehicle electronic control device according to the third embodiment.
In FIG. 8, the circuit board 42 includes a through hole 42c and a wiring 16c instead of the through hole 12c and wiring 16a of the circuit board 12 in FIG. The through hole 42c is arranged in an intermediate region RM1 between the mounting region of the electronic component 11a and the mounting region of the electronic component 11b so as to sandwich the wiring region of the wiring 16c. At this time, the wiring 16c can connect the terminals 17a and 17b in a straight line, and can connect the terminals 17a and 17b through the shortest route. Further, the through hole 42c can be arranged so as to leave only the wiring area between the electronic components 11a and 11b, allowing the terminals 17a and 17b to be connected through the shortest route, while preventing thermal interference between the electronic components 11a and 11b. Can be suppressed.

FIG. 9 is a cross-sectional view showing the configuration around electronic components 11a and 11b applied to the in-vehicle electronic control device according to the fourth embodiment.
In the configuration of FIG. 9, the heat dissipating members 18a, 18b of FIG. 3 are removed, and a gap is provided between each electronic component 11a, 11b and the circuit board 12. Thereby, each electronic component 11a, 11b can be prevented from coming into contact with the circuit board 12, and the stress applied to each electronic component 11a, 11b can be alleviated.

FIG. 10 is a sectional view showing the configuration around electronic components 11a and 11b applied to the on-vehicle electronic control device according to the fifth embodiment.
In the configurations of FIGS. 1 to 9, the circuit board 12 is arranged between the electronic components 11a and 11b and the rectangular convex part 21, but in the configuration of FIG. Electronic components 11a and 11b are arranged.

At this time, the electronic components 11a, 11b can be brought into contact with the rectangular convex portion 21 via the heat dissipation members 19a, 19b, and the heat generated in the electronic components 11a, 11b can be transferred to the rectangular convex portion without passing through the circuit board 12. You can escape to 21. Furthermore, heat transmitted horizontally across the circuit board 12 between the electronic components 11a and 11b can be blocked by the through hole 12c, and thermal interference between the electronic components 11a and 11b can be reduced.

FIG. 11 is a cross-sectional view showing the configuration around electronic components 11a and 11b applied to the in-vehicle electronic control device according to the sixth embodiment.
In FIG. 11, the circuit board 52 includes a recess 12f instead of the through hole 12c of the circuit board 12 in FIG. The recess 12f can be formed on the mounting surface side of the electronic components 11a and 11b. The number and arrangement positions of the recesses 12f can be set in the same manner as the through holes 12c. The recessed portion 12f can be used as a low thermal conductivity portion having a lower thermal conductivity than the circuit board 52.

Here, by providing N recesses 12f in the circuit board 52, it is possible to reduce thermal interference between the electronic components 11a and 11b, suppress the temperature rise of the electronic components 11a and 11b, and It is possible to suppress an increase in the length of the wiring between the electronic components 11a and 11b, and achieve high-speed signal transmission between the electronic components 11a and 11b.

At this time, the upper layer of the circuit board 52 cuts off the thermal interference path between the electronic components 11a and 11b, and the lower layer of the circuit board 52 allows heat generated from the electronic components 11a and 11b to escape to the rectangular convex portion 21. In addition, the depth of the recess 12f can be adjusted.

In addition, in the embodiment described above, an example was shown in which a through hole or a recess is arranged in the intermediate region RM1 between the mounting region of the electronic component 11a and the mounting region of the electronic component 11b. A mixture of through holes and recesses may be arranged in the intermediate region RM1 between the mounting region of the component 11b and the mounting region of the component 11b. At this time, in the intermediate region RM1 between the mounting area of the electronic component 11a and the mounting area of the electronic component 11b, for example, a recess is arranged at a position close to the electronic components 11a, 11b, and a recess is placed at a position far from the electronic components 11a, 11b. A through hole may be arranged in the.

FIG. 12 is a cross-sectional view showing the configuration around the electronic component 11 applied to the in-vehicle electronic control device according to the first comparative example.
In FIG. 12, the electronic component 11 is individually mounted on the circuit board 62 instead of the electronic components 11a and 11b in FIG. In the circuit board 62, the through hole 12c shown in FIG. 3 has been removed. The circuit board 62 includes a thermal via 62a instead of the thermal vias 12a and 12b in FIG.

The electronic component 11 includes terminals 17 . A heat dissipation member 18 is provided between the electronic component 11 and the circuit board 62, and a heat dissipation member 19 is provided between the rectangular convex portion 21 and the circuit board 62.

When the electronic component 11 is mounted alone on the circuit board 62, thermal interference does not occur between the electronic components, and the temperature of the electronic component 11 does not rise due to thermal interference.

FIG. 13 is a cross-sectional view showing the configuration around electronic components 11a and 11b applied to a vehicle-mounted electronic control device according to a second comparative example.
In FIG. 13, in the circuit board 72, the through hole 12c of FIG. 3 has been removed. The other configuration of the on-vehicle electronic control device in FIG. 13 is the same as the configuration in FIG. 3.

FIG. 14 is a plan view showing the configuration of a circuit board on which electronic components 11a and 11b of FIG. 13 are mounted.
In FIG. 14, the circuit board 72 does not have a through hole in the intermediate region RM1 between the mounting regions of the electronic components 11a and 11b. Therefore, there is no restriction on the placement position of the wiring 72a formed in the intermediate region RM1 between the mounting areas of the electronic components 11a and 11b, and the electronic components 11a and 11b can be connected through the shortest route.

FIG. 15 is a cross-sectional view showing the direction of heat propagation in the thermal interference path between the electronic components 11a and 11b in FIG. 13.
In FIG. 15, since the circuit board 72 does not have a through hole in the intermediate region RM1 between the mounting areas of the electronic components 11a and 11b, the heat Ha and Hb generated in each of the electronic components 11a and 11b is transferred horizontally to the circuit board 12. transmitted in the direction. Therefore, thermal interference occurs between the electronic components 11a and 11b, resulting in an increase in the temperature of each electronic component 11a and 11b due to the thermal interference.

FIG. 16 is a cross-sectional view showing the configuration around electronic components 11a and 11b applied to a vehicle-mounted electronic control device according to a third comparative example.
In FIG. 16, the circuit board 82 includes a single hole 82a instead of the N through holes 12c in FIG. The rest of the configuration of the on-vehicle electronic control device in FIG. 16 is the same as the configuration in FIG. 3.

FIG. 17 is a plan view showing the configuration of a circuit board on which electronic components 11a and 11b of FIG. 16 are mounted.
In FIG. 17, the single hole 82a is formed in the circuit board 82 so as to protrude from the intermediate region RM1 between the mounting regions of the electronic components 11a and 11b.

By providing the single hole 82a in the circuit board 82, it is possible to suppress thermal interference between the electronic components 11a and 11b, and it is possible to suppress a rise in temperature of each electronic component 11a and 11b due to thermal interference. On the other hand, since the single hole 82a protrudes from the intermediate region RM1 between the mounting areas of the electronic components 11a and 11b, the heat radiation paths ka and kb in FIG. Sexuality decreases. Therefore, in the configuration in which the circuit board 82 is provided with a single hole 82a, the temperature reduction effect due to the suppression of thermal interference between the electronic components 11a and 11b may be lower than the temperature increase effect due to the reduction in heat dissipation of the circuit board 82. The temperature rise of parts 11a and 11b may increase.

Further, since the single hole 82a is arranged at a position crossing the intermediate region RM1, a wiring region for electrically connecting the electronic components 11a and 11b cannot be secured in the intermediate region RM1. Therefore, in order to connect the electronic components 11a and 11b with wiring, it is necessary to bypass the single hole 82a, which increases the length of the wiring that connects the electronic components 11a and 11b. The transmission speed of signals between the terminals 11b and 11b decreases.

FIG. 18 is a diagram showing a comparison of the temperatures of electronic components when metal and high heat conductive resin are used as casing materials for fixing a circuit board on which electronic components are individually mounted.
In Figure 18, 3.5W electrons are generated when a metal with a thermal conductivity of 90 W/m K and a high thermal conductive resin with a thermal conductivity of 10, 20, and 30 W/m K are used as housing materials. Component temperatures of components and 10W electronic components are shown.

When a high heat conductive resin is used as the housing material, the temperature of the 3.5W electronic component and the 10W electronic component increases compared to when metal is used. However, if high thermal conductivity resins with thermal conductivities of 10, 20, and 30 W/m・K are used as the housing material, the component temperature of 3.5W electronic components and 1.0W electronic components can be kept below 150℃. be able to.

FIG. 19 is a diagram illustrating a comparison of the temperatures of electronic components when metal and high heat conductive resin are used as casing materials for fixing circuit boards on which electronic components are mounted adjacent to each other.
In FIG. 19, when metal is used as the housing material, even when the electronic components are mounted adjacent to each other on the circuit board, the temperature rise is equal to the temperature increase when the electronic components are mounted singly. This is thought to be because when metal is used as the housing material, heat generated by the electronic components is quickly dissipated before thermal interference occurs between the electronic components.

On the other hand, when a high heat conductive resin is used as the housing material, the temperature of the 3.5W electronic component and the 10W electronic component increases compared to when the electronic component is mounted singly. This is because when a highly thermally conductive resin is used as the housing material, the heat dissipation performance of the heat generated by the electronic components decreases, and a temperature rise occurs due to thermal interference between the electronic components.

For this reason, when a high thermal conductivity resin is used as the housing material, thermal interference between electronic components can be suppressed by providing a low thermal conductivity section on the circuit board located in the middle area between the mounting areas of the electronic components. It is possible to reduce the temperature rise of electronic components. At this time, by discretely arranging the low thermal conductivity portions in the intermediate region, a wiring region between electronic components can be provided in the intermediate region, and the length of wiring between electronic components can be shortened.

FIG. 20 is a diagram comparing and illustrating numerical examples of temperature increases in the first, second, and third embodiments and the first, second, and third comparative examples.
In the first comparative example, FIG. 20 shows the component temperature when a 3.5W electronic component is used as the electronic component 11 in FIG. 12, and the component temperature when a 1.0W electronic component is used. In the first, second and third embodiments and the second and third comparative examples, 3.5W electronic components and 1 The temperature of each component when using .0W electronic components is shown. Furthermore, a high heat conductive resin with a thermal conductivity of 10 W/m·K was used as the housing material.

In the second comparative example, as shown in FIG. 15, thermal interference occurs between the electronic components 11a and 11b, resulting in a temperature increase of 3° C. compared to the first comparative example. In the third comparative example, since there is a single hole 82a in the intermediate region RM1 between the mounting areas of the electronic components 11a and 11b, thermal interference can be suppressed between the electronic components 11a and 11b, compared to the first comparative example. The temperature rise is suppressed to 1.5°C for 3.5W electronic components and 2.5°C for 1.0W electronic components.

In the first, second, and third embodiments, there are N through holes in the intermediate region RM1 between the mounting areas of the electronic components 11a and 11b, so compared to the first comparative example, the 3.5W electronic component has only one through hole. For 1.0W electronic components at .5°C, the temperature rise is suppressed to 2.5°C. At this time, the N through holes are arranged at positions where the component temperatures of the 3.5W electronic component and the 1.0W electronic component are 150° C. or lower.

Here, even in the configuration in which N through holes are provided in the intermediate region RM1 between the mounting regions of the electronic components 11a and 11b, a single hole is provided across the intermediate region RM1 between the mounting regions of the electronic components 11a and 11b in FIG. It is possible to obtain the same effect of suppressing temperature rise as in the configuration in which 82a is provided.

FIGS. 21A to 21C are plan views showing other examples of intermediate regions between mounting regions of electronic components.
In FIG. 21(a), it is assumed that mutually adjacent electronic components 11d and 11e are shifted and arranged on the circuit board. At this time, the intermediate region RM2 between the mounting regions of the electronic components 11d and 11e can be set within a region that includes all straight paths that cause thermal interference between the electronic components 11a and 11b. As a result, by discretely providing through holes or recesses in the intermediate region RM2 of the circuit board, the wiring area between adjacent electronic components can be secured in the intermediate region RM2, while thermal interference between electronic components can be effectively prevented. Can be suppressed.

In FIG. 21(b), it is assumed that electronic components 11f and 11g having different sizes are arranged adjacent to each other on a circuit board. At this time, the intermediate region RM3 between the mounting regions of the electronic components 11f and 11g can be set within a region that includes all linear paths that cause thermal interference between the electronic components 11f and 11g. As a result, by discretely providing through holes or recesses in the intermediate region RM3 of the circuit board, the wiring area between adjacent electronic components can be secured in the intermediate region RM3, while thermal interference between electronic components can be effectively prevented. Can be suppressed.

In FIG. 21(c), it is assumed that three electronic components 11h, 11i, and 11j are arranged adjacent to each other on a circuit board. At this time, the intermediate region RM4 between the mounting regions of the three electronic components 11h, 11i, and 11j must be set within a region that includes all linear paths that cause thermal interference between any of the electronic components 11h, 11i, and 11j. I can do it. At this time, the intermediate region RM4 can be set continuously for the three electronic components 11h, 11i, and 11j. As a result, by discretely providing through holes or recesses in the intermediate region RM4 of the circuit board, the wiring area between adjacent electronic components can be secured in the intermediate region RM4, while thermal interference between electronic components can be effectively prevented. Can be suppressed.

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

1 in-vehicle electronic control device, 11a to 11c electronic component, 12 circuit board, 13 base, 14 cover, 15 connector, 15a pin terminal, 16a to 16c wiring, 17a, 17b terminal, 12a, 12b thermal via, 12c through hole, 18a , 18b, 19a, 19b heat dissipation member, 21 rectangular convex portion, 22 screw

Claims (11)

a circuit board on which a first electronic component and a second electronic component are mounted adjacent to each other;
a casing for fixing the circuit board;
a low thermal conductivity portion provided on the circuit board and having a lower thermal conductivity than the circuit board;
The low thermal conductivity parts are discretely arranged in a plurality of rows at positions that do not protrude from an intermediate area between the first electronic component mounting area and the second electronic component mounting area. Electronic control unit. The electronic control device according to claim 1, wherein the low thermal conductivity portion is a through hole or a recess provided in the circuit board. The circuit board includes wiring that electrically connects the first electronic component and the second electronic component,
The electronic control device according to claim 1, wherein the wiring is arranged in the intermediate region so as to avoid a position of the low thermal conductivity part. The electronic control device according to claim 3, wherein the wiring is disposed in the intermediate region between the low heat conduction parts or at a position adjacent to the low heat conduction parts. The electronic control according to claim 3, wherein the low thermal conductivity section occupies an area in the intermediate region that allows the wiring and suppresses thermal interference between the first electronic component and the second electronic component. Device. The electronic control device according to claim 5, wherein the low thermal conductivity portion occupies an area of 10% or more and 90% or less of the intermediate region. The electronic control device according to claim 1, wherein the thermal conductivity of the casing is 30 W/m·K or less. The electronic control device according to claim 1, wherein a calorific value of the first electronic component and a calorific value of the second electronic component are different from each other. The electronic control device according to claim 1, wherein the low thermal conductivity section is arranged at a position where a component temperature of the first electronic component and a component temperature of the second electronic component are 150 degrees Celsius or less. The low thermal conductivity section is arranged at a position where a temperature decreasing effect due to suppression of thermal interference between the first electronic component and the second electronic component exceeds a temperature increasing effect due to a decrease in heat dissipation of the circuit board. Item 1. The electronic control device according to item 1. 2. The low thermal conductivity section is arranged at a position where heat dissipation outside the intermediate region is not reduced and thermal interference between the first electronic component and the second electronic component can be suppressed. Electronic control unit.

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