JP2019075511A - Electronic device - Google Patents

Abstract

To provide a technology for reducing a size while performing heat dissipation of a circuit board.SOLUTION: An electronic device 1 includes a circuit board 20 and a housing 10. The circuit board has a mounting unit 21 on which an electronic component is mounted and a through hole 25. The housing accommodates the circuit board, and a vent 12 is attached to one side and a fan F is attached to the other across the through hole. Also, the circuit board has a heat transfer member 23a that connects the mounting unit and the through hole.SELECTED DRAWING: Figure 1

Description

  The present invention relates to electronic devices.

  Conventionally, for example, there is an electronic device provided with a circuit board that controls a vehicle. Such an electronic device is provided with a heat sink that dissipates the heat generated in the circuit board (see, for example, Patent Document 1).

Unexamined-Japanese-Patent No. 2006-210611

  However, in the prior art, it is difficult to miniaturize the electronic device by the provision of the heat sink. In particular, in the case where the electronic device is mounted on a vehicle, downsizing is required because the mounting space is limited.

  This invention is made in view of the above, Comprising: It aims at providing the electronic device which can be miniaturized, performing heat dissipation of a circuit board.

  In order to solve the problems described above and achieve the purpose, the electronic device according to the embodiment includes a circuit board and a housing. The circuit board has a mounting portion on which an electronic component is mounted, and a through hole. The housing accommodates the circuit board, and a fan is attached to the vent and the other on one side of the through hole. Further, the circuit board has a heat transfer member connecting the mounting portion and the through hole.

  According to the present invention, the circuit board can be miniaturized while radiating heat.

FIG. 1 is a schematic view of an electronic device. FIG. 2 is a schematic cross-sectional view of the electronic device. FIG. 3 is a diagram showing the relative positional relationship between the through holes and the through holes. FIG. 4 is a view showing the cross-sectional shape of the through hole. FIG. 5 is a diagram (part 1) illustrating an electronic device according to a modification. FIG. 6 is a second diagram showing the electronic device according to the modification.

  Hereinafter, the electronic device according to the embodiment will be described in detail with reference to the accompanying drawings. Note that the present invention is not limited by the embodiments described below.

  First, an outline of the electronic device 1 according to the embodiment will be described with reference to FIG. FIG. 1 is a diagram showing an outline of the electronic device 1. Note that FIG. 1 shows a three-dimensional orthogonal coordinate system including a Z-axis whose positive direction is upward in the vertical direction, in order to simplify the description. Such an orthogonal coordinate system may also be shown in other drawings used in the following description. FIG. 1 is a schematic cross-sectional view of the electronic device 1 along the X axis.

  The electronic device 1 is, for example, a control device that controls a navigation device or an audio of a vehicle. However, not limited to this, the electronic device 1 can be applied to other control devices.

  As shown in FIG. 1, the electronic device 1 includes a housing 10, a circuit board 20, and a fan F. The housing 10 accommodates the circuit board 20, and has an attachment portion 11 to which the fan F is attached on the upper surface, and a vent 12 on the lower surface.

  The fan F is an exhaust fan that exhausts air from the inside of the housing 10 to the outside of the housing 10, takes in air to the inside of the housing 10 through the vent 12, and exhausts the air to the outside of the housing 10. In FIG. 1, the flow of air is indicated by a white arrow. The fan F is not limited to the exhaust fan, and may be an intake fan that sucks air into the housing 10.

  The housing 10 is, for example, a conductive metal case, and also functions as a ground of a circuit board 20 described later. The housing 10 may be made of a plastic member such as resin.

  The circuit board 20 includes a mounting portion 21 on which the electronic component Ec is mounted, a resist 22, a first heat transfer member 23a, a second heat transfer member 23b, an insulating layer 24, and a through hole 25. In addition, as shown in FIG. 1, although this embodiment demonstrates the case where the circuit board 20 is a double-sided board in which the electronic component Ec is mounted in both surfaces, the circuit board 20 is a single-sided board or a multilayer board. May be

  The mounting unit 21 is a mounting pad, and the electronic component Ec is mounted on the mounting pad via the solder 21 b. The electronic component Ec includes, for example, an integrated circuit, a resistor, a capacitor, a transistor, and the like.

  The resist 22 is a protective film for protecting the surface of the circuit board 20 and a wiring pattern (not shown), and is formed of, for example, an insulating material such as a photosensitive resin or a thermosetting resin.

  The first heat transfer member 23 a is formed, for example, of copper plating by a sputter deposition method or a plating method. The first heat transfer member 23a may be a signal wiring for the electronic component Ec or a printed wiring such as a ground wiring or may be provided separately from the printed wiring.

  The first heat transfer member 23 a extends to the through hole 25 and covers the through hole 25. That is, the through holes 25 are plated through holes coated by copper plating.

  The second heat transfer member 23 b is, for example, a heat transfer sheet having an insulating property, and is formed of ceramic, silicon or the like. The first heat transfer member 23 a and the second heat transfer member 23 b thermally connect the mounting portion 21 and the through hole 25.

  The insulating layer 24 is, for example, a resin having an insulating property. As described above, since the circuit board 20 is a double-sided board, the first heat transfer member 23 a and the second heat transfer member 23 b are disposed on both sides of the main surface of the insulating layer 24. In addition, it is also possible to use a member with high heat conductivity as the insulating layer 24 itself, and in this way it is possible to conduct heat more efficiently.

  The through holes 25 are provided through the circuit board 20 and, for example, conduct each layer of the circuit board 20.

  By the way, since the electronic component Ec generates heat during operation, it is necessary to dissipate heat in order to operate properly. For example, in the prior art, the heat dissipation of the electronic component is performed using a heat sink. However, when a heat sink is used, the increase in the number of parts makes it difficult to increase the cost and to miniaturize the electronic device.

  Therefore, in the electronic device 1 according to the embodiment, focusing on the fact that approximately 90% of the heat released from the electronic component Ec is transmitted to the printed wiring, the electronic device 1 is miniaturized.

  Specifically, in the electronic device 1 according to the embodiment, the fan F is provided on one side of the through hole 25 and the vent 12 is provided on the other side. Thus, the air flow can be forced to pass through the through holes 25.

  Then, the heat of the electronic component Ec is collected into the through hole 25 via the first heat transfer member 23a and the second heat transfer member 23b, and the through hole 25 is cooled by the air flow.

  When the through hole 25 is cooled, the temperature gradient between the through hole 25 and the electronic component Ec causes the heat to be conducted from the electronic component Ec to the through hole 25 again via the first heat transfer member 23a and the second heat transfer member 23b. It is eaten.

  That is, the electronic device 1 according to the embodiment can efficiently cool the electronic component Ec by concentrating the heat of the electronic component Ec in the through hole 25 and locally cooling the through hole 25.

  At this time, since the electronic device 1 according to the embodiment does not require a heat sink as in the prior art, the number of parts does not have to be increased. Further, in the electronic device 1 according to the embodiment, since the fan F may generate the air flow locally to the through holes 25, use of the fan F smaller than that in the case of cooling the entire circuit board 20 is required. Is possible.

  From these, the electronic device 1 according to the embodiment can be miniaturized while performing heat dissipation of the circuit board 20.

  Next, the case where the electronic device 1 includes a plurality of circuit boards 20 will be described with reference to FIG. FIG. 2 is a schematic cross-sectional view of the electronic device 1. In the following description, parts that are the same as the parts that have already been described will be assigned the same reference numerals as the parts that have already been described, and redundant descriptions will be omitted. Further, in the following description, the circuit board 20 is simplified, and the mounting portion 11 and the like are omitted.

  As shown in FIG. 2, the housing 10 includes a column 15 a and a beam 15 b. The column portion 15 a fixes the two circuit boards 20 and supports the housing 10 in the vertical direction from the inside.

  Further, the column portion 15 a divides the space between the electronic component Ec and the through hole 25 in a direction intersecting the main surface of the circuit board 20. In other words, the pillars 15 a play a role of limiting the flow path of the air flow between the vent 12 and the fan F.

  If the above-described flow path is not limited by the column portion 15a, the air flow may stagnate inside the housing 10 after passing through the vent 12, and the through hole 25 may not be cooled sufficiently.

  That is, by limiting the flow path of the air flow by the column portion 15 a, it is possible to efficiently collect the air flow after passing through the vent 12 in the through hole 25. Thereby, the through holes 25 can be efficiently cooled by the collected air flow.

  The beam portion 15 b is a planar member that supports the column portion 15 a from the direction along the main surface of the circuit board 20. That is, the electronic component Ec and the through hole 25 are arranged in the space divided by the column portion 15a and the beam portion 15b.

  Further, the beam portion 15 b has a through hole 16 in a space on the through hole 25 side separated by the column portion 15 a. That is, the air flow that has passed through the vent 12 is guided to the fan F through the through holes 25 and the through holes 16.

  Here, the details of the through holes 16 will be described with reference to FIGS. 3 and 4. FIG. 3 is a diagram showing the relative positional relationship between the through holes 25 and the through holes 16.

  As shown in FIG. 3, the through holes 16 are, for example, disposed on a substantially straight line along the axial direction of the through holes 25. Preferably, as shown in FIG. 3, for example, the center 25 a of the through hole 25 and the center 16 a of the through hole 16 are preferably disposed on the axis (on the Z axis) of the through hole 25.

  As a result, the air flow can be guided from the through hole 16 to the through hole 25 without impairing the flow velocity. That is, the through holes 25 can be cooled efficiently.

  The center 16 a of the through hole 16 does not necessarily have to coincide with the center 25 a in the axial direction, and the center 16 a may be positioned within a predetermined range L (for example, a radius of 5 mm). In addition, in the case where there are a plurality of through holes 16 and a plurality of through holes 25, at least one through hole 16 may be disposed on a substantially straight line with respect to the center 25a.

  Next, the shape of the through hole 16 will be described with reference to FIG. FIG. 4 is a view showing the cross-sectional shape of the through hole 16. As shown in FIG. 4, the through hole 16 is formed in a tapered shape that is tapered in the direction of passing the air flow.

  In the present embodiment, since the fan F is an exhaust fan, the air flow passes through the through hole 16 from the Z-axis negative direction side to the positive direction side. For this reason, the through hole 16 has a shape tapered from the lower surface opening d2 to the upper surface opening d1.

  By doing this, the air flow passing through the through hole 16 has its flow passage gradually limited from the lower surface opening d2 to the upper surface opening d1. This makes it possible to accelerate the flow velocity of the air flow when passing through the through hole 16.

  Therefore, the flow rate per unit time of the air flow passing through the through hole 25 is increased, so that the through hole 25 can be cooled efficiently. At this time, the through holes 25 may be formed in a tapered shape in the same manner as the through holes 16.

  Thus, by providing the through holes 16 in the beam portion 15b, it is possible to control the amount of air flow passing through the through holes 25 per unit time.

  As described above, the electronic device 1 according to the embodiment includes the circuit board 20 and the housing 10. The circuit board 20 has a mounting portion 21 on which the electronic component Ec is mounted, and a through hole 25. The housing 10 accommodates the circuit board 20, and the fan F is attached to the vent hole 12 and the other on one side of the through hole 25. Further, the circuit board 20 has heat transfer members (a first heat transfer member 23 a and a second heat transfer member 23 b) which connect the mounting portion 21 and the through holes 25. Therefore, according to the electronic device 1 according to the embodiment, it is possible to miniaturize the circuit board 20 while performing heat dissipation.

  Next, electronic devices 1A and 1B according to the modification will be described with reference to FIGS. 5 and 6. 5 and 6 are diagrams showing electronic devices 1A and 1B according to the modification, respectively.

  First, an electronic device 1A according to a first modification will be described with reference to FIG. As shown in FIG. 5, the electronic device 1A is provided with one fan F as opposed to the case where the electronic device 1 shown in FIG.

  The fan F illustrated in FIG. 5 collects the air flows that have passed through the two flow paths and discharges the air to the outside of the housing 10. As described above, in the electronic device 1 (electronic device 1A), the through holes 25 may be cooled locally, and each flow path is limited by the column portion 15a. It is possible to cool the through hole 25. Further, in the electronic device 1A, cost reduction and downsizing can be achieved by the omission of the number of fans F compared to the electronic device 1.

  Next, an electronic device 1B according to a second modification will be described with reference to FIG. The electronic device 1B shown in FIG. 6 differs from the electronic devices 1 and 1A in that the electronic device 1B shown in FIG.

  As shown in FIG. 6, in the electronic device 1 </ b> B, the airflow path from the intake fan Fb to the fan F is formed in one connection. That is, in the electronic device 1B, air is taken in from the intake fan Fb to the inside of the housing 10 by the intake fan Fb and the fan F, and the air is exhausted from the fan F.

  That is, in the electronic device 1B, the air flow is allowed to pass through the through hole 25 by both the intake fan Fb and the fan F. Thus, the air flow is accelerated by both the intake fan Fb and the fan F, so that the through hole 25 can be cooled efficiently. As shown in the figure, the intake fan Fb also functions as the vent 12.

  By the way, although the case where vent hole 12 is formed in the upper surface or the undersurface of case 10 was explained by the embodiment mentioned above, it is not limited to this. That is, for example, as long as the vent 12 is formed on the side surface of the housing 10 or the like, as long as it is disposed on the other side of the fan F with the through hole 25 interposed therebetween, the position does not matter.

  In the embodiment described above, the case where the through holes 25 are through holes for conduction of the circuit board 20 has been described, but the through holes 25 may be provided for cooling. In such a case, the diameter of the through hole 25 may be made larger than the diameter of the through hole for conduction. As a result, the area to be cooled by the through holes 25 is increased, which makes it possible to cool more efficiently.

  Further effects and modifications can be easily derived by those skilled in the art. Thus, the broader aspects of the invention are not limited to the specific details and representative embodiments represented and described above. Accordingly, various modifications may be made without departing from the spirit or scope of the general inventive concept as defined by the appended claims and their equivalents.

DESCRIPTION OF SYMBOLS 1, 1A, 1B Electronic apparatus 10 Housing | casing 11 Mounting part 12 Ventilation hole 15a Column part 15b Beam part 16 Through hole 20 Circuit board 21 Mounting part 23a 1st heat-transfer member 23b 2nd heat-transfer member 25 Through hole

Claims (5)

A mounting part on which an electronic component is mounted, and a circuit board having through holes;
The circuit board is accommodated, and an air vent is provided on one side of the through hole, and a housing is provided on the other side of the through hole.
The circuit board is
An electronic device comprising a heat transfer member connecting the mounting portion and the through hole. The housing is
The electronic device according to claim 1, further comprising: a pillar portion that divides a space between the mounting portion and the through hole in a direction intersecting the main surface of the circuit board. The housing is
It further comprises a planar beam portion supporting the column portion from the direction along the main surface of the circuit board,
The beam portion is
The electronic device according to claim 2, wherein a through hole is provided in a space on the side of the through hole partitioned by the pillar portion. The through hole is
The electronic device according to claim 3, wherein when the fan is an exhaust fan, the fan is tapered toward the fan. The through hole is
It arrange | positions on the substantially straight line along the axial direction of the said through hole. The electronic device of Claim 3 or 4 characterized by these.

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