Electronic devices

Abstract

To provide an electronic device that facilitates the miniaturization of the entire device. [Solution] The electronic device 1 comprises a conductive housing 10 having an internal space S, a circuit board 20 housed in the internal space and on which electronic components are mounted, and an insulating resin sheet 50 disposed between the inner wall surface of the housing and the circuit board. The resin sheet is made of thermoplastic resin and is three-dimensionally molded to conform to the shape of the inner wall surface of the housing. The circuit board has a number of electronic components mounted on it, including heat-generating components 40 such as power semiconductors, and a heat dissipation member 60 is disposed between the heat-generating components and the inner wall surface of the housing.

Description

Technical Field

[0001] The present disclosure relates to an electronic device.

Background Art

[0002] Patent Document 1 discloses a solid molded article for electrical insulation. In this molded article, a sheet material having electrical insulation is bent so as to have a curved surface.

Prior Art Documents

Patent Documents

[0003]

Patent Document 1

Summary of the Invention

Problems to be Solved by the Invention

[0004] For example, in an in-vehicle electronic device, a circuit board may be disposed inside a housing. When the housing has conductivity, in order to ensure insulation, it is necessary to increase the distance between the circuit board and the housing, which may make it difficult to miniaturize the entire device.

[0005] An object of the present disclosure is to provide an electronic device that facilitates miniaturization of the entire device.

Means for Solving the Problems

[0006] The electronic device according to the present disclosure includes a conductive housing having an internal space, a circuit board accommodated in the internal space and on which electronic components are mounted, and an insulating resin sheet disposed between an inner wall surface of the housing and the circuit board. The resin sheet is made of a thermoplastic resin and is three-dimensionally molded along the shape of the inner wall surface of the housing.

[0007] In this configuration, the resin sheet is three-dimensionally molded to conform to the shape of the inner wall surface of the enclosure, thus forming a physical insulating layer that conforms to the shape of the enclosure between the inner wall surface of the enclosure and the circuit board. This reduces the distance required to ensure insulation between the enclosure and the circuit board compared to cases where insulation relies solely on spatial distance. As a result, dead space inside the enclosure is reduced, making it possible to miniaturize electronic devices.

[0008] An example of an electronic component may include a heat-generating component. The resin sheet may have openings at positions corresponding to where the heat-generating component is placed. Between the heat-generating component and the housing, a heat dissipation member may be interposed through the openings to conduct heat from the heat-generating component to the housing.

[0009] One example of a resin sheet may be fixed to the inner wall surface of the housing using double-sided tape.

[0010] One example of an electronic device may be an onboard charger or DC-DC converter mounted in the vehicle. [Effects of the Invention]

[0011] According to this disclosure, it is possible to provide an electronic device that facilitates miniaturization of the entire device. [Brief explanation of the drawing]

[0012] [Figure 1] Figure 1 is a schematic cross-sectional view showing an example of an electronic device. [Modes for carrying out the invention]

[0013] In the following description, the same reference numeral will be used for elements that are identical or have the same function, and redundant explanations will be omitted. Note that the electronic device in this embodiment may be, for example, a power conversion device such as an onboard charger or DC-DC converter mounted on a vehicle.

[0014] As shown in Figure 1, an example of an electronic device 1 comprises a conductive housing 10, a circuit board 20 housed in the internal space S of the housing 10, and a resin sheet 50 that insulates the housing 10 from the circuit board 20.

[0015] The enclosure 10 comprises a case 11 for housing electronic components and a lid 12 fixed to the case 11. The case 11 is made of a metal material. For example, the case 11 may be made of aluminum die-cast, which has excellent thermal conductivity. In this case, the case 11 can function as a heat sink for dissipating heat from the circuit board 20 housed in the internal space S.

[0016] The lid 12 closes the opening of the case 11. For example, the lid 12 may be a plate-like body that has the same shape as the opening of the case 11 in a plan view. The lid 12 may be fastened to the case 11 by fastening members such as screws while the opening of the case 11 is closed. The lid 12 may be made of a metal material so that it can function as a heat sink, similar to the case 11. In this embodiment, the lid 12 may be made of die-cast aluminum.

[0017] Multiple flow channels 13 may be formed inside the wall of the housing 10 in the illustrated example. As described above, when the housing 10 is used as a heat sink, a heat exchange medium may flow through the flow channels 13. For example, the heat exchange medium may be a cooling medium such as cooling water. One example of a flow channel 13 may be formed inside the wall (bottom wall) that forms the bottom of the case 11.

[0018] In Figure 1, the housing 10 is depicted as having a rectangular shape in cross-section, but the housing 10 can take on various shapes depending on various conditions such as the location where it is placed, the shape of the components it houses, and the required strength. For example, the inner walls of the case 11 and lid 12 may be provided with various uneven shapes, as well as bent sections such as inward and outward corners. In addition, ribs may be formed on the inner walls of the case 11 and lid 12 to increase strength.

[0019] Numerous electronic components, including heat-generating components 40 such as power semiconductors, are mounted on the circuit board 20. The circuit board 20 in this example may be a printed circuit board (PCB). In the example in Figure 1, only the heat-generating components 40 mounted on both the top and bottom surfaces of the circuit board 20 are depicted, but other electronic components such as transformers, coils, and capacitors may also be mounted on the circuit board 20. A high voltage (e.g., 400V or more) from the battery is applied to these electronic components and the wiring patterns on the board. In this case, the circuit board 20 becomes highly potential relative to the housing 10 (case 11 and lid 12).

[0020] In one example, a thermal interface material (TIM) is placed between the heat-generating component 40 and the inner wall surface of the housing 10. The thermal interface material 60 is, for example, a gap filler containing a thermally conductive filler, a thermal gel, etc., and has the function of dissipating the heat generated by the heat-generating component 40 to the housing 10, which functions as a heat sink. The thermal interface material 60 also has the function of supporting the heat-generating component 40 within the housing 10, thereby positioning the circuit board 20 in a predetermined location. If the package of the heat-generating component 40 is not insulated, the thermal interface material 60 may have insulating properties. Conversely, if the package of the heat-generating component 40 is insulated, the thermal interface material 60 does not need to have insulating properties.

[0021] In the illustrated example, heat dissipation members 60 are placed between the heat-generating component 40 mounted on the upper surface of the circuit board 20 and the lid 12, and between the heat-generating component 40 mounted on the lower surface of the circuit board 20 and the case 11. As a result, heat from the heat-generating component 40 on the upper surface of the circuit board 20 is conducted to the lid 12, and heat from the heat-generating component 40 on the lower surface of the circuit board 20 is conducted to the case 11.

[0022] The resin sheet 50 is configured to insulate between the housing 10 and the circuit board 20. An example of the resin sheet 50 is formed of a thermoplastic resin having excellent electrical insulation properties such as polyethylene terephthalate (PET). The thickness of the resin sheet 50 is not particularly limited as long as three-dimensional molding is possible. As an example, the thickness of the resin sheet 50 may be about 0.05 mm to 1 mm. The resin sheet 50 according to the present embodiment is pre-formed three-dimensionally (three-dimensional molding) so as to have a shape along the shape of the inner wall surface of the housing 10. That is, by three-dimensionally molding the resin sheet 50, the shape of the surface of the resin sheet 50 facing the inner wall surface of the housing 10 can have substantially the same shape as the shape of the inner wall surface of the housing 10. Thereby, the resin sheet 50 is housed in the internal space S of the housing 10 in a state of being in full or partial contact with the inner wall surface. In the present embodiment, since the resin sheet 50 is formed along the inner surface of the housing 10, as will be described later, the resin sheet 50 and the housing 10 can be fixed with a double-sided tape 70.

[0023] The resin sheet 50 in the illustrated example is composed of a first resin sheet 51 having a shape along the inner wall surface of the case 11 and a second resin sheet 52 having a shape along the inner wall surface (lower surface) of the lid 12. The first resin sheet 51 and the second resin sheet 52 may each be composed of a single resin sheet.

[0024] The first resin sheet 51 and the second resin sheet 52 each have openings 51a and 52a at positions corresponding to the positions where the heat dissipation member 60 is disposed. The heat dissipation member 60 connects the heat generating component 40 and the housing 10 through the openings 51a and 52a. The outer periphery of the heat dissipation member 60 connecting the heat generating component 40 and the case 11 through the opening 51a and the inner periphery of the opening 51a may be in close contact with each other. Also, the outer periphery of the heat dissipation member 60 connecting the heat generating component 40 and the lid 12 through the opening 52a and the inner periphery of the opening 52a may be in close contact with each other.

[0025] In one example, the resin sheet 50 may be formed by vacuum forming using a mold corresponding to the inner surface shape of the case 11. By using vacuum forming, the resin sheet 50 can be molded inexpensively and with high precision to match the complex inner surface shape of the case 11. The first resin sheet 51 is positioned to cover the inner wall surface of the case 11 and insulates the case 11 from the circuit board 20. The second resin sheet 52 is positioned to cover the inner wall surface of the lid 12 and insulates the lid 12 from the circuit board 20.

[0026] The resin sheet 50 may be fixed to the inside of the housing 10 by an adhesive member. In one example, the resin sheet 50 is fixed to the inner wall surface of the housing 10 by double-sided tape 70. In the illustrated example, the double-sided tape 70 is placed between the first resin sheet 51 and the case 11 to fix the first resin sheet 51 to the case 11. The double-sided tape 70 is also placed between the second resin sheet 52 and the lid 12 to fix the second resin sheet 52 to the lid 12. The double-sided tape 70 may be attached to multiple spaced positions on the resin sheet 50.

[0027] As described above, the electronic device 1 comprises a conductive housing 10 having an internal space S, a circuit board 20 housed in the internal space S and on which electronic components 40 are mounted, and an insulating resin sheet 50 placed between the inner wall surface of the housing 10 and the circuit board 20. The resin sheet 50 is made of thermoplastic resin and is three-dimensionally molded to conform to the shape of the inner wall surface of the housing 10.

[0028] In this configuration, the resin sheet 50 is three-dimensionally molded to conform to the shape of the inner wall surface of the housing 10, thereby forming a physical insulating layer between the inner wall surface of the housing 10 and the circuit board 20 that conforms to the shape of the housing 10. This reduces the distance required to ensure insulation between the housing 10 and the circuit board 20 compared to when insulation between the housing 10 and the circuit board 20 depends solely on spatial distance. As a result, dead space inside the housing 10 can be reduced, making it possible to miniaturize the electronic device 1.

[0029] An example of an electronic component may include a heat-generating component 40. The resin sheet 50 may have openings 51a and 52a at positions corresponding to where the heat dissipation member 60 is placed. Between the heat-generating component 40 and the housing 10, a heat dissipation member 60 may be interposed through the openings 51a and 52a to conduct heat from the heat-generating component 40 to the housing 10. In this configuration, it is possible to achieve both insulation by the resin sheet 50 and cooling of the heat-generating component 40 by the heat dissipation member 60. That is, by having the resin sheet 50 completely cover the inner wall surface of the housing 10, a wide-area insulation is ensured, while openings 51a and 52a are provided where heat conduction is necessary, and the heat dissipation member 60 is interposed, thereby securing a heat dissipation path from the heat-generating component 40 to the housing 10.

[0030] One example of a resin sheet 50 may be fixed to the inner wall surface of the housing 10 using double-sided tape 70. In this configuration, since the resin sheet 50 is three-dimensionally molded to conform to the shape of the inner wall surface of the housing 10, the position of the resin sheet 50 is determined by the uneven shape of the housing 10 when the resin sheet 50 is placed inside the housing 10. Therefore, the resin sheet 50 can be sufficiently held in place by simple fixing means such as double-sided tape 70 without using strong fixing means such as screws. This reduces the number of parts and assembly man-hours, contributing to reduced manufacturing costs and improved productivity. The heat resistance temperature of the double-sided tape 70 may be around 100°C to 150°C.

[0031] One example of electronic device 1 may be an onboard charger or DC-DC converter mounted on a vehicle. This configuration allows for miniaturization of high-voltage equipment while being constrained by the vehicle's mounting space. Specifically, onboard chargers and DC-DC converters handle high voltage from the battery, which would normally require a large insulation distance, making the housing size prone to becoming large. In this disclosure, by using a three-dimensionally molded resin sheet 50, insulation can be ensured within a limited housing size. Furthermore, even in environments where vibrations occur during vehicle operation, the resin sheet 50 is less likely to shift within the housing 10, thus maintaining high reliability.

[0032] Examples of each form of this disclosure have been described above with reference to the drawings, but this disclosure is not limited to the above forms.

[0033] For example, in the above embodiment, vacuum forming was exemplified as a method for forming the resin sheet 50, but the invention is not limited to this. The resin sheet 50 may be three-dimensionally formed by other well-known forming methods such as blow forming or press forming.

[0034] Furthermore, the material of the resin sheet 50 is not limited to PET, but can be various thermoplastic resins with insulating properties and moldability, such as polypropylene (PP), polycarbonate (PC), polyethylene (PE), polyphthalamide (PPA), polybutylene terephthalate (PBT), polyphenylene sulfide (PPS), and ABS resin.

[0035] Furthermore, although double-sided tape 70 was exemplified as a means for fixing the resin sheet 50 in the above embodiment, the means are not limited to this. For example, the resin sheet 50 may be adhered to the inner wall surface of the housing 10 with an adhesive. Alternatively, the resin sheet 50 may be fixed by being sandwiched between the case 11 and the lid 12 when the housing 10 is assembled.

[0036] Furthermore, although the above embodiment shows an example in which the resin sheet 50 is divided into a first resin sheet 51 on the case 11 side and a second resin sheet 52 on the lid 12 side, the embodiment is not limited to this. For example, the resin sheet 50 may be configured as an integrated member in which the first resin sheet 51 and the second resin sheet 52 are connected. Also, the first resin sheet 51 and the second resin sheet 52 may be further divided.

[0037] Furthermore, although an example was shown in which the resin sheet 50 completely covers the inner wall surface of the housing, if the area requiring insulation is localized, the resin sheet may be arranged to cover only a portion of the inner wall surface of the housing.

[0038] Embodiments relating to this disclosure may be shown as follows: [1] A conductive housing having an internal space, A circuit board, on which electronic components are mounted, is housed in the aforementioned internal space, The enclosure comprises an insulating resin sheet disposed between the inner wall surface of the enclosure and the circuit board, The aforementioned resin sheet is made of thermoplastic resin and is three-dimensionally molded to conform to the shape of the inner wall surface of the housing, in an electronic device. [2] The aforementioned electronic component includes a heat-generating component. The resin sheet has an opening at a position corresponding to the position where the heat-generating component is placed. The electronic device according to [1], wherein a heat dissipation member is interposed between the heat-generating component and the housing through the opening to conduct heat from the heat-generating component to the housing. [3] The electronic device according to [1] or [2], wherein the resin sheet is fixed to the inner wall surface of the housing by double-sided tape. [4] The electronic device is an onboard charger or DC-DC converter mounted on a vehicle, as described in any of [1] to [3]. [Explanation of Symbols]

[0039] 1...Electronic device, 10...Housing, 20...Circuit board, 40...Heat-generating component, 50...Resin sheet, 51a...Opening, 52a...Opening, 60...Heat dissipation member, 70...Double-sided tape, S...Internal space.

Claims

1. A conductive housing having an internal space, A circuit board, on which electronic components are mounted, is housed in the aforementioned internal space, The enclosure comprises an insulating resin sheet disposed between the inner wall surface of the enclosure and the circuit board, The aforementioned resin sheet is made of thermoplastic resin and is three-dimensionally molded to conform to the shape of the inner wall surface of the housing, in an electronic device.

2. The aforementioned electronic component includes a heat-generating component. The resin sheet has an opening at a position corresponding to the position where the heat-generating component is placed. The electronic device according to claim 1, wherein a heat dissipation member is interposed between the heat-generating component and the housing through the opening, thereby conducting heat from the heat-generating component to the housing.

3. The electronic device according to claim 1, wherein the resin sheet is fixed to the inner wall surface of the housing by double-sided tape.

4. The electronic device according to any one of claims 1 to 3, wherein the electronic device is an onboard charger or DC-DC converter mounted on a vehicle.

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