JP6961902B2 - Component mounts and electronic devices - Google Patents

Description

The present invention relates to a component mount having a heat-generating electronic component and an electronic device including the component mount.

In recent years, as a control unit for electric power steering, an electronic control unit (ECU) including a power supply system board equipped with a power supply circuit, a control system board for generating a control signal, and the like has been used. The ECU generates a control signal for driving a motor for assisting the steering force of the driver, for example, based on the output from the steering torque sensor of the steering wheel, the vehicle speed sensor, or the like. As a component constituting the drive circuit of the motor, for example, a heat-generating switching element such as a power MOSFET is used. Therefore, a heat sink is installed in the ECU to efficiently dissipate the heat generated by the heat-generating electronic component.

For example, Patent Document 1 includes a printed circuit board on which a plurality of heat generating elements are mounted, and a metal case fixed to the printed circuit board via a plurality of screws. An electronic control device that comes into contact with the heat conductive member of the system is described. Further, Patent Document 2 describes a semiconductor device having a semiconductor layer, a connection electrode provided on one surface of the semiconductor layer, and a heat radiating portion provided on the other surface of the semiconductor layer.

JP-A-2002-134970 Japanese Unexamined Patent Publication No. 2011-249430

With the recent miniaturization of electronic devices and the high-density mounting of components, improvement of heat dissipation characteristics for heat-generating electronic components is required. As a countermeasure, electronic components on a substrate are required as described in Patent Document 1. A structure in which a heat sink such as a metal case is brought into contact with the upper surface of the metal case is widely adopted.

However, if the electronic component is mounted in an inclined posture with respect to the substrate surface, the clearance between the electronic component and the heat sink is widened, so that the heat dissipation efficiency of the electronic component is lowered, and as a result, the electronic device malfunctions. May lead to. Since such a problem may occur due to the structure of the land portion on the substrate surface, the terminal layout of the electronic component, or both of them, the parallelism of the electronic component to the substrate surface can be increased. Optimization is needed.

In view of the above circumstances, an object of the present invention is to provide a component mount and an electronic device capable of increasing the parallelism of electronic components with respect to the substrate surface.

In order to achieve the above object, the component mount according to one embodiment of the present invention includes an electronic component and a wiring board.
The electronic component has a first surface having a heat radiating portion and a second surface having an electrode terminal and opposite to the first surface.
The wiring board has an insulating base material, a conductor pattern, and an insulator pattern. The conductor pattern includes a first conductor portion extending uniaxially over a mounting area of the electronic component, is electrically connected to the electrode terminal, and is on the second surface side of the insulating base material. Formed on the surface . The insulator pattern includes an opening provided on the first conductor portion and facing the electrode terminal, supports both ends of the second surface in the uniaxial direction, and supports the insulating base material and the conductor. Cover the surface of the pattern .

In the component mount, the first conductor portion that is electrically connected to the terminal electrode of the electronic component and is formed on the surface of the insulating base material on the second surface side is uniaxially connected to the component mounting region on the wiring board. In addition to being formed so as to extend over the first conductor portion , both ends of the second surface of the electronic component in the uniaxial direction are supported on the first conductor portion of the insulating base material and the conductor pattern. Since the insulator pattern covering the surface is provided, the parallelism of the electronic component with respect to the substrate surface is improved. As a result, the heat dissipation efficiency from the electronic component to the heat sink is improved, and the desired heat dissipation characteristics can be stably obtained.

The electrode terminal is composed of a plurality of terminal portions including a first terminal portion that is electrically connected to the first conductor portion and a second terminal portion that is parallel to the first terminal portion. The conductor pattern may further have a second conductor portion that is electrically connected to the second terminal portion.
The second terminal portion may be composed of a single electrode or may be composed of a plurality of electrodes.

Of the plurality of terminal portions, the first terminal portion may have the largest area.
As a result, the area occupied by the first conductor portion becomes relatively large, so that the electronic component is supported more stably.

An electronic device according to an embodiment of the present invention includes the component mounting body and a heat sink which is arranged so as to face the wiring board and is connected to the heat radiating portion via a heat conductive member. Has a heat radiating terminal as the heat radiating unit.

According to the present invention, the parallelism of the electronic component with respect to the substrate surface can be increased, and the heat dissipation property of the heat sink can be improved.

It is schematic cross-sectional view of the main part which shows the structure of the component mounting body which concerns on one Embodiment of this invention. It is the upper surface side perspective view and the lower surface side perspective view which show schematicly the whole structure of the electronic component in the said component mounting body. It is the schematic plan view of the main part of the wiring board in the said component mounting body. It is the schematic plan view of the main part of the wiring board which concerns on a comparative example. FIG. 4 is a schematic cross-sectional view taken along the line YY in FIG. It is a schematic plan view of the main part which shows one modification of the structure of the wiring board in the said component mounting body. It is a schematic plan view of the main part which shows the other modification of the structure of the wiring board in the said component mounting body.

Hereinafter, embodiments of the present invention will be described with reference to the drawings.

FIG. 1 is a schematic cross-sectional view of a main part showing a configuration of a component mounting body 100 according to an embodiment of the present invention.
In the figure, the X-axis, the Y-axis, and the Z-axis show three axial directions orthogonal to each other, and the Z-axis corresponds to the thickness direction (height direction) of the component mounting body 100.

The component mounting body 100 of the present embodiment includes an electronic component 10 and a wiring board 20 that supports the electronic component 10. The component mounting body 100 is configured as, for example, a power supply circuit board or a control circuit board of various electronic devices, and not only the electronic component 10 but also a plurality of circuit components (not shown) are mounted on the wiring board 20.

The electronic component 10 is composed of a heat-generating electronic component. Typical examples of such electronic components include switching elements such as power MOSFETs (Metal Oxide Semiconductor Field Effect Transistors). In addition, various electronic components such as an insulated gate bipolar transistor (IGBT) and a thyristor can be mentioned.

The electronic component 10 is surface-mounted on the wiring board 20 by a reflow soldering method. In the present embodiment, as shown in FIG. 1, the component mounting body 100 further includes a heat sink 30 that faces the wiring board 20 with the electronic component 10 interposed therebetween. The heat sink 30 is typically composed of a structure such as a metal plate or a case, and is thermally connected to the electronic component 10 to dissipate heat from the electronic component 10. The heat sink 30 may be fixed to the wiring board 20 or may be fixed to a housing portion (not shown) of an electronic device that supports the wiring board 20.

2A and 2B are a top perspective view and a bottom perspective view schematically showing the overall configuration of the electronic component 10.

As shown in the figure, the electronic component 10 is composed of a rectangular parallelepiped-shaped semiconductor package component. The size of the electronic component 10 is not particularly limited, and has, for example, a rectangular planar shape having a side length of 5 mm to 10 mm. The electronic component 10 has a front surface portion 11 (first surface) facing the heat sink 30 and a back surface portion 12 (second surface) on the opposite side (opposing the wiring board 20). The front surface portion 11 and the back surface portion 12 are formed of a plane parallel to the XY plane, the front surface portion 11 is provided with a heat dissipation terminal 110 as a heat dissipation portion, and the back surface portion 12 is provided with an electrode terminal 120. There is.

The heat radiating terminal 110 is thermally connected to the heat sink 30 via a heat conductive member 42 attached to the surface portion 11. The heat conductive member 42 has, for example, an insulating property, and a resin material such as a heat conductive adhesive or a heat conductive pressure-sensitive adhesive sheet is adopted. The heat radiating terminal 110 is composed of a single terminal having a rectangular planar shape, and is arranged at a substantially central portion of the surface portion 11. Of course, the heat dissipation terminal 110 is not limited to this example, and may be composed of a plurality of terminals arranged in a predetermined pattern on the surface portion 11. By forming the heat radiating terminal 110 with a metal material having high heat radiating property, the heat radiating property of the electronic component 10 can be further improved.

The electrode terminal 120 corresponds to an external terminal of the electronic component 10 and is electrically connected to a land portion on the wiring board 20. In the present embodiment, the electrode terminal 120 is composed of a plurality of terminal portions including a first terminal portion 121 and a second terminal portion 122.

The first terminal portion 121 is composed of a single terminal having a rectangular planar shape, and is arranged at a substantially central portion of a back surface portion 12. On the other hand, the second terminal portion 122 is composed of a plurality of terminals (four in this example) having a rectangular planar shape, and is arranged at intervals along one side portion of the back surface portion 12. Of the first terminal portion 121 and the second terminal portion 122, the first terminal portion 121 has the largest area, and extends from the substantially central portion of the back surface portion 12 to the peripheral portion on one side in the Y-axis direction. Occupies the area. The first terminal portion 121 and the second terminal portion 122 are arranged so as to face each other in the Y-axis direction on the back surface portion 12, and one end of each protrudes outward (sideways) from the back surface portion 12. It is configured to do.

The shapes and layouts of the terminal portions 121 and 122 shown in the drawings are examples, and it goes without saying that they can be appropriately changed according to the type and size of the parts.

The wiring board 20 is typically composed of a multilayer wiring board in which an insulating base material made of synthetic resin or the like and a conductor layer made of copper foil or the like are alternately laminated. One surface of the wiring board 20 is configured as a mounting surface 21 on which the electronic component 10 is mounted.

As shown in FIG. 1, the mounting surface 21 of the wiring board 20 has a conductor pattern 22 and an insulator pattern 23. The conductor pattern 22 is typically composed of a copper foil having a predetermined pattern shape formed on the surface of the insulating base material 24. The insulator pattern 23 is typically composed of a conductor pattern 22 and a solder resist having a predetermined thickness that covers the surface of the insulating base material 24.

FIG. 3 is a schematic plan view of a main part for explaining the configuration of the mounting surface 21.

As shown in FIG. 3, the conductor pattern 22 has a first conductor portion 221 and a second conductor portion 222. The first conductor portion 221 is electrically connected to the first terminal portion 121 of the electronic component 10 (see FIGS. 1 and 2B), and the second conductor portion 222 is the second terminal portion of the electronic component 10. Each is electrically connected to 122 (see FIG. 2B).

The first conductor portion 221 is formed in a band shape extending over the mounting region 20A of the electronic component 10 on the mounting surface 21 in the uniaxial direction (X-axis direction). The first conductor portion 221 has a width dimension equal to or larger than the length of the first terminal portion 121 along the Y-axis direction, and a length dimension across the first terminal portion 121 in the X-axis direction. The tip portion 221a is configured to be located outside the component mounting area 20A. On the other hand, the second conductor portions 222 are arranged in the X-axis direction at predetermined intervals so as to correspond to each of the second terminal portions 122.

The insulator pattern 23 covers the conductor pattern 22 and the insulating base material 24 on the mounting surface 21 as described above, while the land portion connected to the electrode terminals 120 (first and second terminal portions 121, 122). It has openings 23a and 23b for forming 51 and 52. The openings 23a and 23b are typically formed at predetermined positions on the mounting surface 21 using photolithography techniques.

The opening 23a is provided on the first conductor portion 221 facing the first terminal portion 121. The opening 23a has a substantially rectangular planar shape, and is formed in the same area as or slightly larger than the land portion 51 (first terminal portion 121). In particular, in the present embodiment, the length of the side of the opening 23a along the Y-axis direction is formed to be slightly larger than the width dimension of the land portion 51 (first conductor portion 221) along the Y-axis direction. ..

The opening 23b is provided on the end of the second conductor 222 facing each of the second terminals 122. The opening 23b has a substantially rectangular planar shape, and is formed in the same area as or slightly larger than the land portion 52 (second terminal portion 122). In particular, in the present embodiment, the length of the side of the opening 23b along the X-axis direction is formed to be slightly larger than the width dimension of the land portion 52 (second conductor portion 222) along the X-axis direction. The length of the side of the opening 23b along the Y-axis direction is formed to be slightly larger than the length dimension of the land portion 52 along the Y-axis direction.

The conductor pattern 22 (first and second conductor portions 221 and 222) is formed by the electrode terminals 120 (first and second) of the electronic component 10 via the conductive bonding material 41 filled in the land portions 51 and 52. It is electrically connected to the terminal portions 121 and 122) of the above (see FIG. 1). As the joining material 41, a brazing material such as lead-free solder is typically used. The bonding material 41 is previously applied and filled on the land portions 51 and 52 by a screen printing method or the like, and then undergoes a mounting process, a reflow process, or the like, and the electronic component 10 is placed on the mounting surface 21 in the component mounting area 20A (FIG. 2). See). As a result, the component mounting body 100 is manufactured. The bonding material 41 is not limited to the solder material, and may be a conductive paste or an anisotropic conductive paste containing metal particles.

At this time, the openings 23a and 23b of the insulator pattern 23 have a function of preventing the bonding material 41 from flowing out to regions other than the land portions 51 and 52. That is, since the opening areas of the openings 23a and 23b are limited, a sufficient amount of joining material 41 for joining is secured on the land portions 51 and 52. Further, since the openings 23a and 23b are individually formed corresponding to the individual land portions 51 and 52, a short circuit between the land portions is prevented.

Further, the insulator pattern 23 is formed on the insulating base material 24 and the conductor pattern 22 with a predetermined thickness by a printing method, a spin coating method, or the like, and the conductor pattern 22 is formed on the insulating base material 24 with a predetermined thickness. Is formed by. Then, the insulator pattern 23 is provided on each surface so as to follow the step between the conductor pattern 22 and the insulating base material 24. Therefore, the insulator pattern 23 includes a first region 231 covering the conductor pattern 22 (a region shown by shading and diagonal lines in FIG. 3) and a second region 232 covering the insulating base material 24 (net in FIG. 3). The first region 231 and the second region 232 typically have a height difference corresponding to the thickness of the conductor pattern 22.

In the component mounting body of the present embodiment, the first terminal portion 121 of the electrode terminals 120 of the electronic component 10 occupies the main area of the back surface portion 12 of the electronic component 10, and is mounted on the mounting surface 21 of the wiring board 20. Of the conductor patterns 22 provided, the first conductor portion 221 connected to the first terminal portion 121 is formed so as to straddle (or cross) the component mounting area 20A in the uniaxial direction (X-axis direction in FIG. 3). ing. Therefore, as shown in FIG. 1 (corresponding to the cross-sectional view in the X-ray direction in FIG. 3), the back surface portion 12 of the electronic component 10 extends over the uniaxial direction with the land portion 51 (opening 23a) interposed therebetween. It is supported by the first region 231 of the insulator pattern 23 that covers the conductor portion 221 of 1. That is, both ends of the back surface portion 12 of the electronic component 10 in the X-axis direction are supported by the first region 231 of the insulator pattern 23. As a result, the electronic component 10 can be mounted with high parallelism to the surface (mounting surface 21) of the wiring board 20.

On the other hand, as shown in FIG. 4, the first conductor portion 221 does not straddle (do not cross) the component mounting region 20A in the X-axis direction, for example, its tip portion 221a is located within the region of the opening 23a. In the formed wiring board 200 according to the comparative example, the first region 231 of the insulator pattern 23 covering the first conductor portion 221 is unevenly distributed on one side (right side in FIG. 4) of the component mounting region 20A. become. Then, as shown in FIG. 5, which corresponds to the cross section in the YY line direction in FIG. 4, the electronic components 10 mounted in the component mounting area 20A have different heights across the land portion 51 (opening 23a). Since it is supported by the first region 231 and the second region 232 of the insulator pattern 23, the posture is inclined obliquely with respect to the surface of the wiring board 200.

When the electronic component 10 is mounted in an inclined posture with respect to the surface of the wiring board 200, the surface portion 11 of the electronic component 10 is also inclined, so that the thickness of the heat conductive member 42 is made uniform by the inclination of the electronic component 10. The clearance between the heat sink 30 and the surface portion 11 cannot be narrowed. For this reason, a uniform heat dissipation effect cannot be obtained in the surface of the surface portion 11, which may lead to malfunction of the electronic device. Such a problem becomes more remarkable as the size of the electronic component 10 increases.

On the other hand, according to the present embodiment, since the electronic component 10 is mounted with high parallelism to the surface (mounting surface 21) of the wiring board 20, the surface portion 11 of the electronic component 10 and the heat sink 30 The clearance between the two can be narrowed, and a uniform heat dissipation effect can be stably obtained in the surface of the surface portion 11 without causing variation in heat transfer characteristics. As a result, a high heat dissipation effect can be obtained for the electronic component 10 having a large heat generation amount, and stable operating characteristics of the electronic device can be ensured.

Further, even when a plurality of heat-generating electronic components are mounted on the wiring board 20, the component mounting area of each electronic component is configured in the same manner as described above, so that each electronic component with respect to the wiring board 20 is desired. Parallelism can be ensured. As a result, a single heat sink 30 enables proper thermal connection with each electronic component, and the desired heat dissipation characteristics of each of these electronic components can be obtained.

Although the embodiments of the present invention have been described above, the present invention is not limited to the above-described embodiments, and it goes without saying that various modifications can be made.

For example, in the above embodiment, the first terminal portion 121 of the electronic component 10 is configured as a part of the electrode terminal 120, but the first terminal portion 121 is a heat dissipation terminal like the heat dissipation terminal 110. It may have a function as.

Further, in the above embodiment, the second terminal portion 122 constituting the electrode terminal 120 of the electronic component 10 is composed of a plurality of terminal portions, but the present invention is not limited to this, and the second terminal portion 122 may be composed of a single terminal portion. good. In this case, as in the wiring board 210 shown in FIG. 6, a single land portion 53 is formed in the second conductor portion 223 connected to the terminal portion via the opening portion 23c.

Similarly, the first terminal portion 121 constituting the electrode terminal 120 of the electronic component 10 may be composed of a plurality of terminal portions. In this case, as in the wiring board 220 shown in FIG. 7, the conductor portions 224 connected to the terminal portions are also composed of a plurality of conductor portions 224, and each conductor portion 224 has a plurality of land portions 54 via the openings 23d. Is formed. By forming each conductor portion 224 so as to straddle the component mounting region 20A in the uniaxial direction, it is possible to support the back surface portion of the electronic component 10 in parallel with the substrate surface.

10 ... Electronic components 20, 210, 220 ... Wiring board 20A ... Parts mounting area 22 ... Conductor pattern 23 ... Insulator patterns 23a to 23d ... Openings 24 ... Insulating base material 30 ... Heat sink 41 ... Bonding material 42 ... Heat conductive member 51 ~ 54 ... Land part 100 ... Component mount 110 ... Heat dissipation terminal (heat dissipation part)
120 ... Electrode terminal 121 ... First terminal portion 122 ... Second terminal portion 221 ... First conductor portion 222 ... Second conductor portion 231 ... First region 232 ... Second region

Claims (3)

An electronic component having a first surface having a heat radiating portion and a second surface having an electrode terminal and opposite to the first surface.
An insulating base material and a first conductor portion extending uniaxially over a mounting area of the electronic component, electrically connected to the electrode terminal, and on the second surface side of the insulating base material. The insulating base material includes a conductor pattern formed on the surface and an opening provided on the first conductor portion and facing the electrode terminal to support both ends of the second surface in the uniaxial direction. A component mount body including an insulator pattern that covers the surface of the conductor pattern , and a wiring board having the same. The component mount according to claim 1.
The electrode terminal is composed of a plurality of terminal portions including a first terminal portion that is electrically connected to the first conductor portion and a second terminal portion that is parallel to the first terminal portion.
Of the plurality of terminal portions, the first terminal portion has the largest area and has the largest area.
The conductor pattern is a component mounting body further having a second conductor portion that is electrically connected to the second terminal portion. The component mount according to claim 1 or 2,
A heat sink, which is arranged to face the wiring board and is connected to the heat radiating portion via a heat conductive member, is provided.
The electronic component is an electronic device having a heat radiating terminal as the heat radiating portion.

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