JP2023177300A - On-vehicle electronic device - Google Patents

Abstract

To efficiently ensure, at the same time, vibration resistance of a heavy component and heat dissipation of a heating component, in a configuration where the heavy component and the heating component are mounted on a substrate.SOLUTION: An on-vehicle electronic device includes: a housing having a heat dissipation property; and a substrate which is bonded to the housing via a heat-conductive adhesive layer, and on which a plurality of components are mounted. The plurality of components include: a heating component; and a heavy component which is heavier than the heating component. The substrate has: the heavy component disposed on a first surface; and the heating component disposed on a second surface opposite to the first surface. The heat-conductive adhesive layer is bonded to the second surface of the substrate in a manner thermally connected to the heating component and also in a manner overlapping the heavy component when viewed in a direction perpendicular to the substrate.SELECTED DRAWING: Figure 2B

Description

The present disclosure relates to in-vehicle electronic devices.

A technology in which a metal heat sink is placed parallel to the board on which heat-generating components are mounted, and a heat-dissipating sheet is placed between the heat-generating components on the board and the metal heat sink screws that are screwed onto the heat sink. It has been known.

Japanese Patent Application Publication No. 2004-296878

However, as mentioned above, in the conventional technology, when heavy components and heat-generating components are mounted on a board, it is difficult to efficiently ensure the vibration resistance of the heavy components and the heat dissipation of the heat-generating components at the same time. is difficult.

Therefore, in one aspect, the present disclosure efficiently realizes simultaneously ensuring vibration resistance of heavy components and heat dissipation of heat generating components in a configuration in which heavy components and heat generating components are mounted on a board. The purpose is to

In one aspect, a casing having heat dissipation properties,
a board bonded to the casing via a heat conductive adhesive layer and on which a plurality of components are mounted;
The plurality of components include a heat generating component and a heavy component that is heavier than the heat generating component,
The heavy component is disposed on a first surface of the substrate, and the heat generating component is disposed on a second surface opposite to the first surface,
The in-vehicle electronic device is bonded to the second surface of the substrate in such a manner that the heat conductive adhesive layer is thermally connected to the heat generating component and overlaps the heavy component when viewed in a direction perpendicular to the substrate. is provided.

In one aspect, according to the present disclosure, in a configuration in which heavy components and heat generating components are mounted on a board, it is possible to efficiently ensure the vibration resistance of the heavy components and the heat dissipation of the heat generating components at the same time. becomes possible.

FIG. 1 is a perspective view schematically showing an in-vehicle electronic device according to the present embodiment. FIG. 2 is a plan view schematically showing the front side of a board portion of the in-vehicle electronic device. FIG. 2 is a plan view schematically showing the back side of a board portion of the in-vehicle electronic device. FIG. 3 is a plan view schematically showing the back side of the substrate portion and a part of the wiring structure of the inner layer. FIG. 2 is a plan view schematically showing the casing of the in-vehicle electronic device when viewed from the front side of the board portion. FIG. 2 is a perspective view showing a housing of an on-vehicle electronic device. FIG. 2 is a cross-sectional view of an on-vehicle electronic device.

Hereinafter, each embodiment will be described in detail with reference to the accompanying drawings. Note that the dimensional ratios in the drawings are merely examples, and are not limited thereto, and shapes, etc. in the drawings may be partially exaggerated for convenience of explanation.

FIG. 1 is a perspective view schematically showing an in-vehicle electronic device 1 of this embodiment. FIG. 2A is a plan view schematically showing the front side of the board portion 2 of the in-vehicle electronic device 1. FIG. FIG. 2B is a plan view schematically showing the back side of the board portion 2 of the in-vehicle electronic device 1. FIG. Note that in FIG. 2B (as well as FIG. 2C, which will be described later), the heat conductive adhesive layer 50 is schematically shown as a hatched area. FIG. 2C is a plan view schematically showing the back side of the substrate portion 2 and a part of the wiring structure of the inner layer 201. In FIG. 2C, the inner layer 201 of the substrate 20 is partially shown. FIG. 3 is a plan view schematically showing the housing 3 of the in-vehicle electronic device 1 when viewed from the front side of the board portion 2. As shown in FIG. FIG. 3A is a perspective view showing the housing 3 of the in-vehicle electronic device 1. FIG. 4 is a sectional view of the in-vehicle electronic device 1. Note that in FIG. 4, the cover member 4, which is not shown in FIGS. 1, 2A, etc., is also shown.

In FIG. 1 and the like, an X direction and a Y direction are defined as two directions orthogonal to each other. The X direction and the Y direction correspond to the horizontal and vertical directions of the substrate 20, which will be described later, and a plane including the X direction and the Y direction is parallel to the substrate 20. Further, regarding the X direction, an X1 side and an X2 side are defined. Further, regarding the Y direction, a Y1 side and a Y2 side are defined.

In the following description, for convenience of explanation, the vertical direction corresponds to the direction perpendicular to the substrate 20 (described later), the upper side corresponds to the front side of the substrate 20, and the lower side corresponds to the back side of the substrate 20. shall correspond to However, the vertical direction when the in-vehicle electronic device 1 is mounted in the vehicle may be different from the vertical direction in the following description.

The in-vehicle electronic device 1 may be, for example, in the form of an ECU (Electronic Control Unit). In this embodiment, as an example, the in-vehicle electronic device 1 forms a control device that controls a relatively small motor. A relatively small motor may be, for example, a motor smaller than a motor for driving a vehicle, such as a motor that drives gears forming a vehicle drive device, a motor that drives an oil pump, etc. good.

The in-vehicle electronic device 1 includes a board portion 2 and a housing 3.

The board portion 2 includes a board 20 and a connector section 22 for electrically connecting the board 20 to the outside. Note that illustration of the connector portion 22 is omitted in FIG. 1.

The substrate 20 may be in the form of a printed circuit board, for example a multilayer structure with one or more intermediate layers. The substrate 20 is housed or supported in the housing 3. The substrate 20 may be completely housed in the housing 3, or may be housed in the housing 3 with a portion exposed. The substrate 20 may be directly supported by the housing 3 or may be supported via another member.

A plurality of components are mounted on the board 20. All of the plurality of components may be electronic components, or may include components other than electronic components. In this embodiment, as an example, the plurality of electronic components 40 mounted on the board 20 include various electronic components for controlling a relatively small motor. Note that a plurality of components may be mounted on the board 20 with high density in order to reduce the size of the in-vehicle electronic device 1.

In this embodiment, the plurality of electronic components 40 include a heat generating component 410 (hereinafter also simply referred to as "heat generating component 410") to which cooling measures are to be taken, and a heavy component 420 (hereinafter simply referred to as "heat generating component 410") to which vibration damping measures are to be taken. (also referred to as "heavy parts 420").

The heat generating component 410 may be a component that generates heat itself during operation, or a component that generates heat due to heat conducted from other components. The heat-generating component 410 may be a component that has a relatively large power consumption and tends to operate continuously, for example, a component that becomes hot enough to require cooling. The heat generating component 410 may include, for example, a power semiconductor element, a resistor, a microcomputer, a power supply IC (Integrated Circuit), and the like. In FIG. 2A, areas where heat generating components 410 are arranged are indicated by SC10 to SC12. Further, in FIG. 2B, a region where the heat generating component 410 is arranged is indicated by SC13, and in perspective, it is indicated by regions SC10 to SC12 on the front side shown in FIG. 2A.

In this embodiment, as an example, the heat generating component 410 includes switching elements Q1 to Q4 forming an H-bridge circuit 411 and switching elements Q11 to Q16 forming a three-phase bridge rectifier circuit 412. Further, in this embodiment, as an example, the heat generating component 410 includes a shunt resistor R1 (see region S13 in FIG. 2B).

In the illustrated example, the switching elements Q1 and Q2 form upper and lower arms in the H-bridge circuit 411, and are arranged side by side in the Y direction. Switching elements Q3 and Q4 form upper and lower arms in the H-bridge circuit 411, and are arranged side by side in the Y direction. A set of switching elements Q1 and Q2 and a set of switching elements Q3 and Q4 are arranged side by side in the X direction.

Furthermore, in the illustrated example, switching elements Q11, Q13, and Q15 form an upper arm in the three-phase bridge rectifier circuit 412, and are arranged side by side in the X direction. Furthermore, switching elements Q12, Q14, and Q16 form a lower arm in the three-phase bridge rectifier circuit 412, and are arranged side by side in the X direction. A set of switching elements Q11 and Q12 arranged in the Y direction, a set of switching elements Q13 and Q14 arranged in the Y direction, and a set of switching elements Q15 and Q16 arranged in the Y direction are arranged in the X direction. has been done.

According to such an arrangement, each switching element Q1 to Q4 forming the H-bridge circuit 411 and each switching element Q11 to Q16 forming the three-phase bridge rectifier circuit 412 are adjacent to each other in the X direction and the Y direction. They can be arranged in a high density manner. This makes it possible to realize an efficient wiring configuration. Furthermore, the switching elements Q1, Q3, Q11, Q13, and Q15 on the upper arm and the switching elements Q2, Q4, Q12, Q14, and Q16 on the lower arm are arranged side by side in the X direction while being separated in the Y direction. be done. Thereby, in both the H-bridge circuit 411 and the three-phase bridge rectifier circuit 412, the high potential side and the low potential side are spaced apart in the same manner in the Y direction, so an efficient wiring configuration can be realized.

The heavy component 420 is a relatively heavy component, and may include, for example, the heaviest component among all the components mounted on the board 20. For example, the heavy component 420 may have a weight that requires vibration damping measures. Note that a plurality of heavy components 420 may be provided on one substrate 20. The heavy component 420 is a component that generates significantly less heat than the heat generating component 410, but may be a component that does not substantially generate heat. In this embodiment, the heavy component 420 includes an inductor L, as an example. Note that the inductor L may be electrically connected between the connector section 22 and the H-bridge circuit 411.

In this embodiment, as an example, the heavy component 420 is mounted on the front surface of the board 20 together with the switching elements Q1 to Q4 and Q11 to Q16, whereas the shunt resistor R1 is mounted on the back side of the board 20. It is mounted on the surface (the surface facing the bottom surface of the casing 3).

The board 20 includes a wiring pattern 430 that electrically connects the shunt resistor R1 and the connector section 22. The wiring pattern 430 may be formed on the inner layer 201 of the substrate 20, for example, as shown in FIG. 2C.

The housing 3 has heat dissipation properties. The housing 3 may be made of, for example, a material with relatively high heat conductivity (eg, aluminum). The housing 3 may have a heat dissipation structure such as fins (not shown), or may have a coolant flow path such as a cooling water channel.

In this embodiment, the housing 3 is, for example, in the form of a box with an open top. The housing 3 is provided with a substrate portion 2 . Note that a portion of the connector portion 22 of the board portion 2 may be exposed to the outside of the housing 3. The housing 3 supports the substrate portion 2 from below, and the opening at the top may be covered by a cover member 4 (see FIG. 4). Note that, at this time, the back surface of the substrate 20 is oriented to face the bottom surface of the casing 3.

Furthermore, in this embodiment, the housing 3 has a plurality of pedestals 310 that protrude upward on the bottom surface 30. Each pedestal part 310 is formed in a part of the bottom surface 30, and may be solid inside so that it can function as a heat spreader. In this case, the heat capacity of the casing 3 locally becomes relatively large in the region where each pedestal 310 is arranged. In this embodiment, each pedestal section 310 is provided so as to overlap the heat generating component 410 when viewed in the vertical direction (direction perpendicular to the substrate 20). The pedestal section 310 may be provided for each heat generating component 410, and/or one pedestal section 310 may be provided in a manner corresponding to two or more heat generating components 410.

The casing 3 is bonded to the substrate 20 via a heat conductive adhesive layer 50 on a pedestal 310. That is, the heat conductive adhesive layer 50 joins the substrate 20 and the pedestal part 310 (and the casing 3 accordingly) by bonding the back surface of the substrate 20 and the upper surface of the pedestal part 310. .

The thermally conductive adhesive layer 50 may be formed by curing any adhesive that has relatively high thermal conductivity. In this case, the adhesive may contain a filler or the like to improve heat conductivity. The adhesive may have the property of being cured by applying heat, mixing with other materials, or the like. Note that the heat conductive adhesive layer 50 is preferably formed over substantially the entire upper surface of the pedestal portion 310, but may be formed only on a portion. The heat conductive adhesive layer 50 may be formed by applying an adhesive to the upper surface of the pedestal portion 310. In this case, the heat conductive adhesive layer 50 may be formed by curing the applied adhesive while being held (pressed) between the substrate 20 and the pedestal 310.

In this way, the heat conductive adhesive layer 50 can thermally connect each heat generating component 410 and the pedestal 310, so that the heat from the heat generating component 410 can be transferred between the heat conductive adhesive layer 50 and the casing 3. can be efficiently released to the outside through

In this embodiment, a specific pedestal part 310 (hereinafter also referred to as "specific pedestal part 310A" to distinguish it from other pedestal parts 310) among the plurality of pedestal parts 310 and a heat conductive material on it The adhesive layer 50 has a function of increasing the earthquake resistance of the heavy component 420 described above. Specifically, the pedestal portion 310A is arranged so as to overlap the inductor L when viewed in the vertical direction. In addition, in this specification, a mode in which a certain component A overlaps another component B when viewed in a specific direction includes a mode in which one includes the other, a mode in which both completely overlap, and a mode in which both overlap. This is a concept that includes both partially overlapping aspects. It is bonded to the back surface of the substrate 20.

Further, the specific pedestal part 310A has a heat-conductive adhesive layer 50 (hereinafter also referred to as "specific adhesive layer 50A" to distinguish it from other adhesive layers 50) like the other pedestal parts 310. ) is provided. The specific adhesive layer 50A has a function of increasing the bonding strength between the specific pedestal portion 310A and the substrate 20, and also has a function of transmitting heat from the specific heat generating component 410 to the housing 3 (hereinafter referred to as "transfer"). (also referred to as "thermal function"). In this embodiment, the specific heat generating component 410 is, for example, a shunt resistor R1 mounted on the back surface of the substrate 20. In this case, the specific pedestal portion 310A (and the specific adhesive layer 50A accordingly) may overlap the shunt resistor R1 or may overlap the wiring pattern 430 from the shunt resistor R1 when viewed in the vertical direction. . In either case, the heat generated by the shunt resistor R1 can be transmitted to the housing 3 via the specific adhesive layer 50A and released to the outside. In addition, in order to make it easier for the specific pedestal portion 310A (and the specific adhesive layer 50A accordingly) to overlap the shunt resistor R1 or the wiring pattern 430 when viewed in the vertical direction, the shunt resistor R1 is , may overlap with the heavy component 420, or may overlap with the peripheral region of the heavy component 420 (region near the heavy component 420).

In this embodiment, the specific adhesive layer 50A overlaps the wiring pattern 430 from the shunt resistor R1 when viewed in the vertical direction. In this case, the specific adhesive layer 50A can efficiently transfer not only the heat from the shunt resistor R1 but also the heat of the wiring pattern 430 itself to the housing 3. Note that when the wiring pattern 430 is formed on the inner layer 201 of the board 20, the specific adhesive layer 50A may be bonded to a non-component mounting area (flat area) on the back surface of the board 20. In this case, the reliability of the bonded portion can be improved compared to the case of bonding to a region of the substrate 20 with relatively large irregularities (for example, a region where components are arranged).

In this manner, according to this embodiment, the specific pedestal portion 310A (and the specific adhesive layer 50A) is thermally connected to the specific heat generating component 410 and is connected to the heavy component 420 when viewed in the vertical direction. It is bonded to the substrate 20 in an overlapping manner. Thereby, the heat from the specific heat generating component 410 can be efficiently transferred to the housing 3, and the vibration of the heavy component 420 can be efficiently reduced. That is, in a configuration in which the heavy component 420 and the heat generating component 410 are mounted on the substrate 20, it is possible to efficiently ensure the vibration resistance of the heavy component 420 and the heat dissipation performance of the heat generating component 410 at the same time.

More specifically, the heavy component 420 is the inductor L, which is an electronic component that does not substantially generate heat. In this embodiment, even such an electronic component that does not generate substantially heat is intentionally supported by a specific pedestal section 310A via a specific adhesive layer 50A, and the substrate 20 is attached to the specific adhesive layer 50A. A heat generating component 410 mounted on the back surface of the is thermally connected. This allows the specific pedestal portion 310A (and accompanying specific adhesive layer 50A) to have two functions at the same time (ensuring the vibration resistance of the heavy component 420 and ensuring heat dissipation of the heat generating component 410). configuration can be realized. As a result, compared to a configuration in which a pedestal section for ensuring vibration resistance of the heavy component 420 and a pedestal section for ensuring heat dissipation of the heat generating component 410 are provided separately, the board 20 and the in-vehicle electronic device 1 can be made smaller. In particular, when the pedestal part 310 is formed solid, the weight of the casing 3 tends to increase as the area in which the pedestal part 310 is arranged increases. The weight of the casing 3 can be reduced compared to a configuration in which a pedestal section for the holder is provided separately.

Further, in the embodiment described above, the specific adhesive layer 50A is formed by curing the adhesive applied on the specific pedestal portion 310A. In this case, the fixing strength between the substrate 20 and the specific pedestal portion 310A is increased, and a high vibration damping effect on the heavy component 420 placed on the substrate 20 can be realized. That is, a higher vibration damping effect can be achieved than when a heat conductive sheet material such as a thermal sheet is brought into close contact between the pedestal section 310 and the substrate 20 instead of the specific adhesive layer 50A.

The specific pedestal portion 310A (and the specific adhesive layer 50A accordingly) is preferably arranged near the shunt resistor R1 from the viewpoint of enhancing the heat transfer function described above. For example, the position in the wiring pattern 430 overlapping the specific adhesive layer 50A may be closer to the shunt resistor R1 than the intermediate position in the length direction of the wiring pattern 430. Note that the intermediate position in the length direction of the wiring pattern 430 may be an intermediate position based on the wiring length from the shunt resistor R1 to the connector portion 22.

Further, the specific pedestal portion 310A (and the specific adhesive layer 50A accordingly) is preferably used in the wiring pattern from the viewpoint of enhancing the above-mentioned heat transfer function and the function of transmitting the heat of the wiring pattern 430 itself to the casing 3. It has a size corresponding to a wiring width of 430mm. For example, the specific adhesive layer 50A may have a substantially circular shape having a diameter corresponding to the wiring width of the wiring pattern 430, and the wiring pattern 430 may be formed so that the center is located near the widthwise center of the wiring pattern 430. It may be positioned against. In this case, the specific adhesive layer 50A may be inscribed in both widthwise edges of the wiring pattern 430, or may partially protrude. In this case, in the wiring direction of the wiring pattern 430, the minimum error in the width of the specific adhesive layer 50A with respect to the wiring width of the wiring pattern 430 may be, for example, ±20% or less. Further, the specific adhesive layer 50A may have a non-circular shape when viewed in the vertical direction.

Although each embodiment has been described in detail above, it is not limited to a specific embodiment, and various modifications and changes can be made within the scope of the claims. It is also possible to combine all or a plurality of the components of the embodiments described above.

For example, in the embodiment described above, the pedestal part 310 is a part that is formed integrally with the casing 3, but it is a separate piece from the casing 3, and is integrated by being combined with the casing 3. It may also be formed from a member.

Further, in the embodiment described above, the heat conductive adhesive layer 50 is formed by curing the adhesive applied on the pedestal portion 310. However, of the heat conductive adhesive layers 50, the ones other than the specific adhesive layer 50A are formed by bringing a heat conductive sheet material such as a thermal sheet into close contact between the pedestal portion 310 and the substrate 20. You can.

DESCRIPTION OF SYMBOLS 1... Vehicle electronic device, 3... Housing, 20... Board, 50... Heat conductive adhesive layer, 410... Heat generating component, 420... Heavy component, R1... Shunt resistance (resistance), 430...wiring pattern

Claims (5)

a casing with heat dissipation;
a board bonded to the casing via a heat conductive adhesive layer and on which a plurality of components are mounted;
The plurality of components include a heat generating component and a heavy component that is heavier than the heat generating component,
The heavy component is disposed on a first surface of the substrate, and the heat generating component is disposed on a second surface opposite to the first surface,
The in-vehicle electronic device is bonded to the second surface of the substrate in such a manner that the heat conductive adhesive layer is thermally connected to the heat generating component and overlaps the heavy component when viewed in a direction perpendicular to the substrate. . The in-vehicle electronic device according to claim 1, wherein the casing has a pedestal portion that protrudes toward the substrate and is bonded to the heat conductive adhesive layer. The heat generating component includes a resistor,
The in-vehicle electronic device according to claim 1, wherein the heat conductive adhesive layer overlaps a wiring pattern from the resistor when viewed in a direction perpendicular to the substrate. 4. The in-vehicle electronic device according to claim 3, wherein a position in the wiring pattern overlapping the heat conductive adhesive layer is closer to the resistor than a longitudinally intermediate position in the wiring pattern. The in-vehicle electronic device according to claim 3 or 4, wherein the heat conductive adhesive layer has a size corresponding to the wiring width of the wiring pattern.

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