Circuit unit

Abstract

Disclosed is a circuit unit capable of inhibiting or preventing deformation of a circuit substrate caused by molding pressure of a molding resin. The circuit unit (10) includes: a circuit substrate (12); a first electronic component (14) mounted on one surface (20) side of the circuit substrate (12); a first hollow housing (18) mounted on the one surface (20) side of the circuit substrate, the first hollow housing (18) covering the first electronic component (14) by forming a first hollow portion (21) around the first electronic component (14); a deformation inhibiting member (24) mounted on the other surface (22) side of the circuit substrate (12), the deformation inhibiting member (24) being arranged opposite to the first hollow portion (21) in a manner of sandwiching the circuit substrate (12) therebetween to inhibit deformation of the circuit substrate (12); and a molding resin (16) embedding the circuit substrate (12) and the first electronic component (14), the first hollow housing (18), and the deformation inhibiting member (24) mounted on the circuit substrate (12) in the inside.

Description

Technical Field

[0001] This disclosure relates to circuit units. Background Technology

[0002] Patent Document 1 discloses a structure in which a circuit unit in which an electronic component is embedded in molding resin is constructed, and a hollow shell with an internally hollow structure is disposed around the electronic component. In the structure of Patent Document 1, the top and side surfaces of the electronic component are covered by the hollow shell, which is disposed with gaps, thereby protecting the electronic component from adverse effects caused by the molding pressure and heat of the resin during the molding of the resin around the circuit board.

[0003] Existing technical documents

[0004] Patent documents

[0005] Patent Document 1: Japanese Patent Application Publication No. 2023-171548 Summary of the Invention

[0006] The problem that the invention aims to solve

[0007] However, in the circuit unit disclosed in Patent Document 1, the molding pressure of the resin acting on one side of the circuit board at the mounting location of the electronic components and its surrounding area is absorbed or buffered by the hollow portion of the hollow shell. In contrast, the molding pressure of the resin acts directly on the other side of the circuit board. Therefore, in the molding process of the molding resin, if the molding temperature exceeds the glass transition temperature of the circuit board, the rigidity of the circuit board decreases, and the circuit board may deform by being pressed towards the hollow shell side.

[0008] Therefore, a circuit unit capable of suppressing or preventing deformation of a circuit board caused by the molding pressure of a molding resin is disclosed.

[0009] Methods for solving problems

[0010] The circuit unit disclosed herein comprises: a circuit board; a first electronic component mounted on one side of the circuit board; a first hollow housing mounted on the same side of the circuit board, forming a first hollow portion around the first electronic component and covering the first electronic component; a deformation suppression member mounted on the other side of the circuit board, configured opposite to the first hollow portion to suppress deformation of the circuit board by sandwiching the circuit board in the middle; and a molding resin for embedding the circuit board, the first electronic component mounted on the circuit board, the first hollow housing, and the deformation suppression member inside.

[0011] Invention Effects

[0012] According to the circuit unit disclosed herein, deformation of the circuit board caused by the molding pressure of the molding resin can be suppressed or prevented. Attached Figure Description

[0013] Figure 1 This is a longitudinal sectional view showing the circuit unit of Embodiment 1.

[0014] Figure 2 It is shown in a state where the molding resin has been removed. Figure 1 The circuit unit shown is a three-dimensional view viewed from the top side.

[0015] Figure 3 yes Figure 2 The circuit unit shown is viewed from the bottom side in a three-dimensional perspective.

[0016] Figure 4 This is a longitudinal sectional view showing the circuit unit of Embodiment 2.

[0017] Figure 5 This is a longitudinal sectional view showing the circuit unit of Embodiment 3.

[0018] Figure 6 This is a longitudinal sectional view showing the circuit unit of Embodiment 4.

[0019] Figure 7 This is a longitudinal sectional view showing a circuit unit of another embodiment of this disclosure. Detailed Implementation

[0020] <Description of embodiments of this disclosure>

[0021] First, embodiments of this disclosure will be described.

[0022] (1) The circuit unit of the present disclosure comprises: a circuit board; a first electronic component mounted on one side of the circuit board; a first hollow shell mounted on the same side of the circuit board, forming a first hollow portion around the first electronic component and covering the first electronic component; a deformation suppression member mounted on the other side of the circuit board, configured opposite to the first hollow portion to suppress deformation of the circuit board by sandwiching the circuit board in the middle; and a molding resin for embedding the circuit board, the first electronic component mounted on the circuit board, the first hollow shell and the deformation suppression member inside.

[0023] According to the circuit unit of this disclosure, a first electronic component and a first hollow shell covering the periphery of the first electronic component are mounted on one side of a circuit board, and a first hollow portion formed between the first electronic component and the first hollow shell is provided around the first electronic component. Furthermore, a deformation suppression member is mounted on the other side of the circuit board, and this deformation suppression member is disposed opposite to the circuit board, sandwiching the first hollow portion. Thus, in the molding process of molding resin around the circuit board, which mounts the first electronic component, the first hollow shell, and the deformation suppression member, the molding pressure of the resin acting on one side of the circuit board is absorbed or buffered by the first hollow portion. Moreover, in this molding process, the deformation suppression member mounted on the other side of the circuit board can suppress the deformation of the circuit board caused by the molding pressure of the molding resin, which cannot be suppressed when the hollow shell is only provided on one side of the circuit board in a conventional configuration. As a result, even when the molding temperature in the molding process of the molding resin exceeds the glass transition temperature of the circuit board and the rigidity of the circuit board decreases, deformation of the circuit board caused by the molding pressure of the molding resin can be suppressed or prevented.

[0024] It should be noted that the first electronic component mounted on one side of the circuit board can be directly mounted on the conductive path of the circuit board, or it can be mounted on another circuit such as a busbar or flexible printed circuit board placed on one side of the circuit board. Furthermore, the first hollow shell mounted on one side of the circuit board and the second hollow shell mounted on the other side of the circuit board can be directly placed on the circuit board, or they can be mounted on the circuit board via other circuits.

[0025] (2) In (1) above, preferably, the deformation suppression member includes a second hollow shell, which is mounted on the other side of the circuit board and is configured to sandwich the circuit board in the middle, facing the first hollow portion. The second hollow shell, serving as a deformation suppression member, is mounted on the other side of the circuit board and is configured to sandwich the circuit board in the middle, facing the first hollow portion. Therefore, in the molding process of molding resin around the circuit board on which the first electronic component, the first hollow shell, and the second hollow shell are mounted, the molding pressure of the resin acting on one side of the circuit board can be absorbed or buffered by the first hollow portion, and similarly, the molding pressure of the resin acting on the other side of the circuit board can be absorbed or buffered by the second hollow portion, which sandwiches the circuit board in the same way. Therefore, compared to the conventional configuration where a hollow shell is only provided on one side of the circuit board, it is possible to suppress the uneven application of resin molding pressure to one side and the other side of the circuit board. As a result, even when the molding temperature in the molding process of the molding resin exceeds the glass transition temperature of the circuit board and the rigidity of the circuit board decreases, deformation of the circuit board caused by the molding pressure of the molding resin can be suppressed or prevented.

[0026] (3) In (2) above, it is preferable that the first hollow portion and the second hollow portion coincide in the projection of the circuit board in the thickness direction. Since the first hollow portion and the second hollow portion coincide in the projection of the circuit board in the thickness direction, the forming pressure applied to the circuit board can be absorbed or buffered by the hollow portion in the same way, and the deformation of the circuit board can be more effectively prevented or suppressed.

[0027] (4) In (2) or (3) above, preferably, a second electronic component is further provided, which is mounted on the other side of the circuit board and is covered by the second hollow shell via the second hollow portion. The second electronic component mounted on the other side of the circuit board can be covered by the second hollow shell via the second hollow portion, and the second hollow shell can not only absorb the molding pressure of the resin, but also protect the second electronic component.

[0028] (5) In any of (2) to (4) above, preferably, the protrusion dimension of the second hollow housing protruding from the other side of the circuit board is smaller than the protrusion dimension of the first hollow housing protruding from one side of the circuit board. When the purpose of providing the second hollow housing is only to provide a second hollow portion opposite to the first hollow portion, and the second hollow housing also functions to cover electronic components and the electronic components are smaller than those surrounded by the first hollow housing, making the protrusion height of the second hollow housing smaller than the protrusion height of the first hollow housing enables miniaturization of the circuit unit.

[0029] (6) In any of (2) to (5) above, it is preferred that the first hollow shell and the second hollow shell are formed of a material having a glass transition temperature above the molding temperature of the molding resin. Since the first hollow shell and the second hollow shell are formed of a material having a glass transition temperature above the molding temperature of the molding resin, deformation of the first hollow shell and the second hollow shell during molding of the molding resin can be advantageously prevented, and the first hollow portion and the second hollow portion can be reliably maintained, thereby more advantageously suppressing or preventing deformation of the substrate.

[0030] (7) In any of (2) to (5) above, it is preferred that at least one of the first hollow shell and the second hollow shell is formed of metal. The first hollow shell or the second hollow shell formed of metal is less prone to deformation under the influence of the molding temperature of the molding resin, thus advantageously preventing deformation of the hollow shell. Therefore, the first hollow portion of the first hollow shell formed of metal or the second hollow portion of the second hollow shell formed of metal can be reliably maintained, thereby more advantageously suppressing or preventing deformation of the substrate.

[0031] (8) In (1) above, preferably, the deformation suppression member includes a plate member mounted on the other side of the circuit board, arranged opposite to the first hollow portion in such a way that the circuit board is sandwiched in the middle, and the plate member is formed of a material having a glass transition temperature above the molding temperature of the molding resin. Since the plate member constituting the deformation suppression member is formed of a material having a glass transition temperature above the molding temperature of the molding resin, deformation of the plate member during molding of the molding resin can be advantageously prevented. Furthermore, since the plate member is arranged opposite to the first hollow portion in such a way that the circuit board is sandwiched in the middle, the molding pressure of the molding resin from the other side relative to the portion of the circuit board on one side where the first hollow portion is disposed can be borne by the plate member, thereby preventing the molding pressure of the molding resin from being directly transmitted to the circuit board. As a result, deformation of the circuit board toward the first hollow portion side, which is a problem in conventional structures, can be advantageously suppressed or prevented.

[0032] <Details of the embodiments of this disclosure>

[0033] Hereinafter, specific examples of the resin sealing unit of this disclosure will be described with reference to the accompanying drawings. It should be noted that this disclosure is not limited to these examples, and as shown in the claims, it is intended to include all modifications within the meaning and scope equivalent to the claims.

[0034] <Implementation Method 1>

[0035] The following uses Figures 1 to 3 The circuit unit 10 of Embodiment 1 of this disclosure will be described. This circuit unit 10 has a structure in which a circuit board 12 and a first electronic component (specifically, a capacitor 14) are encapsulated within a molding resin 16. The molding resin 16 prevents the circuit board 12 and capacitor 14 from getting wet or being subjected to external forces, and improves heat dissipation when the circuit board 12 and capacitor 14 generate heat. Within the molding resin 16, the capacitor 14 is covered by a first hollow shell 18, preventing heat and pressure from the molding of the molding resin 16 from acting on the capacitor 14. It should be noted that the circuit unit 10 can be arranged in any orientation, but below, "above" refers to... Figure 1 Above and below refer to Figure 1 The bottom and left side refer to Figure 1 The left and right sides refer to Figure 1 The right side and the front side refer to the middle. Figure 1 The front side of the paper in the middle, the back side refers to Figure 1 The description will be provided on the inside of the paper. Furthermore, in the following description, for multiple identical components, sometimes only some components will be labeled with reference numerals, while reference numerals for other components will be omitted.

[0036] <Circuit Unit 10>

[0037] The circuit unit 10 includes: a circuit board 12; a capacitor 14, serving as a first electronic component, mounted on one side of the circuit board 12, namely the upper surface 20 side; and a first hollow housing 18, mounted on the upper surface 20 side of the circuit board 12, forming a first hollow portion 21 around the capacitor 14 and covering the capacitor 14. Additionally, the circuit unit 10 includes a deformation suppression member mounted on the lower surface 22, which is another side of the circuit board 12, and is arranged opposite to the first hollow portion 21 such that the circuit board 12 is sandwiched in the middle, suppressing deformation of the circuit board 12. Furthermore, the circuit unit 10 includes a molding resin 16 in which the circuit board 12, the capacitor 14 mounted on the circuit board 12, the first hollow housing 18, and the deformation suppression member are embedded. In Embodiment 1, the deformation suppression member is composed of a second hollow housing 24 having a second hollow portion 23, and inside the second hollow housing 24 (second hollow portion 23), a field-effect transistor (FET) 26, serving as a second electronic component, is mounted on the lower surface 22 of the circuit board 12.

[0038] <Circuit substrate 12>

[0039] The circuit board 12 of Embodiment 1 is, for example, a known rigid printed circuit board (PCB) that extends in the horizontal direction (orthogonal to the vertical direction). A circuit (not shown) is printed on at least one side of the circuit board 12 (e.g., the upper surface 20). In Embodiment 1, circuits are printed on both sides of the circuit board 12 (the upper surface 20 and the lower surface 22).

[0040] The base plate portion constituting the circuit board 12 is formed, for example, from a known synthetic resin. The glass transition temperature (Tg) of the base plate portion is determined by the material of the synthetic resin constituting the base plate portion and is not limited, but when a general synthetic resin is used as the material of the base plate portion, the glass transition temperature of the base plate portion is, for example, around 140 degrees.

[0041] The first electronic component mounted on the upper surface 20 of the circuit board 12 is not limited, but in Embodiment 1 it is provided as a capacitor 14. As the capacitor 14, a known capacitor is used, so detailed description is omitted.

[0042] <Molding Resin 16>

[0043] As described above, the circuit board 12, which has a first hollow shell 18 on its upper surface 20 and a second hollow shell 24 on its lower surface 22, is covered by molding resin 16. The shape of the molding resin 16 is not limited, but in Embodiment 1, as shown... Figure 1As shown, it has a roughly rectangular longitudinal section and is generally rectangular in shape as a whole. The molding resin 16 is, for example, made of a thermosetting resin. The temperature at which the heat applied to cure the thermosetting resin is determined by the type of thermosetting resin and is not limited, but in Embodiment 1, the temperature applied to cure the thermosetting resin constituting the molding resin 16 is about 170 degrees Celsius. Therefore, the molding temperature at which the molding resin 16 is cured is higher than the glass transition temperature of the circuit board 12 (base plate portion).

[0044] <First Hollow Shell 18>

[0045] The first hollow shell 18 is generally box-shaped with an opening to the bottom or generally cylindrical with an opening to the bottom. In Embodiment 1, the first hollow shell 18 is a generally cylindrical shape with a bottom. It should be noted that... Figure 2 In the diagram, the first hollow shell 18 is shown in a transparent state. The first hollow shell 18 is formed, for example, from a thermosetting resin or a thermoplastic resin with a high glass transition temperature. The resin material constituting the first hollow shell 18 is a material whose glass transition temperature is higher than the temperature at which the molding resin 16 is formed.

[0046] Specifically, the first hollow housing 18 has a circular upper bottom wall portion 28 and an upper surrounding wall portion 30 protruding downward from the outer periphery of the upper bottom wall portion 28. These upper bottom wall portions 28 and upper surrounding wall portions 30 each have a predetermined thickness, although not limited, but are formed, for example, with a substantially constant thickness. The area surrounded by these upper bottom wall portions 28 and upper surrounding wall portions 30 is the first hollow portion 21, within which the first electronic component (capacitor 14) is housed. In other words, the first hollow portion 21 is formed inside the first hollow housing 18, around the capacitor 14. Therefore, the size and shape of the first hollow housing 18 can be appropriately varied depending on the size and shape of the electronic component housed in the first hollow portion 21.

[0047] In Embodiment 1, a flange-shaped portion 34 extending outward in a flange-like manner is provided at the lower opening of the lower end of the upper wall portion 30. That is, the flange-shaped portion 34 extends in a ring shape in the horizontal direction, and in Embodiment 1, the outer shape of the flange-shaped portion 34 is approximately rectangular when viewed from above. The lower surface of the flange-shaped portion 34 extends flatly, and the lower surface of the flange-shaped portion 34 overlaps with the portion around the capacitor 14 in the upper surface 20 of the circuit board 12, thereby fixing the circuit board 12 and the first hollow housing 18 to each other. In Embodiment 1, the circuit board 12 and the first hollow housing 18 are fixed by adhesive bonding, and the overlapping surface of the flange-shaped portion 34 and the circuit board 12 is airtightly sealed. By fixing the circuit board 12 and the first hollow housing 18 in this way, air is sealed inside the first hollow housing 18 (first hollow portion 21).

[0048] <Deformation suppression component (second hollow shell 24)>

[0049] In Embodiment 1, the deformation suppression member includes a second hollow shell 24, which is mounted on the lower surface 22 side of the circuit board 12, forming a second hollow portion 23 opposite to the first hollow portion 21 in a manner that sandwiches the circuit board 12 in the middle. The second hollow shell 24 is generally a box shape with an upward opening or a generally cylindrical shape with a bottom and an upward opening. In Embodiment 1, the second hollow shell 24 is a generally cylindrical shape with a bottom. It should be noted that... Figure 3 The second hollow shell 24 is shown in a transparent state. The second hollow shell 24 is made of the same material as the first hollow shell 18, for example, and the synthetic resin constituting the second hollow shell 24 is made of a material whose glass transition temperature is higher than the temperature at which the molding resin 16 is formed.

[0050] Specifically, the second hollow housing 24 has a circular bottom wall portion 36 and a lower peripheral wall portion 38 protruding upward from the outer periphery of the bottom wall portion 36. These bottom wall portions 36 and lower peripheral wall portions 38 each have a predetermined thickness, although not limited, but are formed, for example, with a substantially constant thickness. The area surrounded by these bottom wall portions 36 and lower peripheral wall portions 38 is the second hollow portion 23, in Embodiment 1, where a second electronic component (FET 26) mounted on the lower surface 22 of the circuit board 12 is housed. In other words, the circuit unit 10 includes the FET 26 as a second electronic component mounted on the lower surface 22 side of the circuit board 12. Furthermore, inside the second hollow housing 24, the second hollow portion 23 is formed around the FET 26, and the FET 26 is covered by the second hollow housing 24 via the second hollow portion 23. It should be noted that a known FET is used as the FET 26, therefore detailed description is omitted. The size and shape of the second hollow housing 24 can be appropriately changed according to the size and shape of the electronic components housed in the second hollow section 23.

[0051] In Embodiment 1, as described above, the first electronic component mounted on the upper surface 20 of the circuit board 12 is a capacitor 14, and the second electronic component mounted on the lower surface 22 of the circuit board 12 is a FET 26. Typically, the height dimension of the FET 26 is smaller than that of the capacitor 14. Therefore, in Embodiment 1, the height dimension (vertical dimension) of the second hollow housing 24 is smaller than the height dimension (vertical dimension) of the first hollow housing 18. Specifically, the protrusion dimension of the second hollow housing 24 from the lower surface 22 of the circuit board 12 is smaller than the protrusion dimension of the first hollow housing 18 from the upper surface 20 of the circuit board 12.

[0052] Furthermore, in Embodiment 1, a flange-shaped portion 42, similar to that of the first hollow housing 18, is also provided at the upper opening of the upper end of the lower peripheral wall portion 38. The flange-shaped portion 42 of the second hollow housing 24 also overlaps with the portion surrounding the FET 26 in the lower surface 22 of the circuit board 12, and the circuit board 12 and the second hollow housing 24 are fixed by adhesive bonding. Thus, in Embodiment 1, the overlapping surface of the flange-shaped portion 42 and the circuit board 12 is hermetically sealed. Moreover, by fixing the circuit board 12 and the second hollow housing 24 in this way, air is sealed inside the second hollow housing 24 (second hollow portion 23).

[0053] In particular, in Embodiment 1, the first hollow portion 21 and the second hollow portion 23 are aligned in the projection of the circuit board 12 along its thickness direction (vertical direction). Specifically, the second hollow shell 24 (including the flange-like portion 42) is formed with the same shape and size as the first hollow shell 18 in plan view, and the thickness dimension (left-right dimension) of the upper peripheral wall portion 30 of the first hollow shell 18 is approximately equal to the thickness dimension (left-right dimension) of the lower peripheral wall portion 38 of the second hollow shell 24. Furthermore, the first hollow shell 18 and the second hollow shell 24 are fixed at a position where they are completely overlapped in plan view, sandwiching the upper and lower sides of the circuit board 12. Thus, the first hollow portion 21 formed on the inner peripheral side of the upper peripheral wall portion 30 in the first hollow shell 18 and the second hollow portion 23 formed on the inner peripheral side of the lower peripheral wall portion 38 in the second hollow shell 24 are positioned in the same position in the vertical projection.

[0054] The circuit unit 10, which is formed in the shape described above, can be manufactured, for example, by the following method. First, a capacitor 14 is mounted on the upper surface 20 of the circuit substrate 12, and a FET 26 is mounted on the lower surface 22 of the circuit substrate 12. Then, on the upper surface 20 of the circuit substrate 12, the flange-like portion 34 of the first hollow housing 18 is overlapped and bonded around the capacitor 14, and on the lower surface 22 of the circuit substrate 12, the flange-like portion 42 of the second hollow housing 24 is overlapped and bonded around the FET 26.

[0055] Then, a circuit board 12, in which the first hollow shell 18 and the second hollow shell 24 are fixed, is placed inside a mold for molding the molding resin 16. Resin material for molding the resin 16 is filled into the mold, and the molding resin 16 is formed by heating and pressurizing. It should be noted that, for example, conductive members (not shown) such as wires or busbars for supplying power to the circuit board 12 are connected to the circuit board 12. During the molding of the molding resin 16, these conductive members are exposed on the outer surface of the molding resin 16. Thus, the circuit unit 10 of Embodiment 1 is completed.

[0056] In the circuit unit 10 thus formed, the circuit board 12, to which the first hollow housing 18 and the second hollow housing 24 are fixed on the upper and lower surfaces 20 and 21, is covered by molding resin 16, thus preventing the circuit board 12 from getting wet or being subjected to external forces. In addition, the capacitor 14 and FET 26 mounted on the circuit board 12 are heated by energizing them, but by using a material with good thermal conductivity as the molding resin 16, the heat generated in the capacitor 14 and FET 26 can be stably dissipated through the molding resin 16.

[0057] According to the circuit unit 10 of Embodiment 1 with the above-described structure, deformation suppression members (second hollow housing 24) are provided on opposite sides in the vertical direction relative to the first hollow housing 18 (first hollow portion 21) surrounding the covering capacitor 14, clamping the circuit board 12. This allows deformation of the circuit board 12 to be suppressed even when heating and pressurizing occur during the molding of the molding resin 16. That is, normally, apart from the glass transition temperature of the circuit board 12 (base plate portion) being lower than the molding temperature of the molding resin 16, air is simply sealed inside the first hollow housing. Therefore, in the case where no deformation suppression member is provided on the lower surface of the circuit board as in the conventional structure, when heating and pressurizing occur during the molding of the molding resin, the molding pressure acts from below, easily causing deformation such as the portion of the circuit board located below the first hollow housing entering the first hollow housing.

[0058] In contrast, by providing a second hollow shell 24 as a deformation-suppressing member on the lower surface 22 side, which is opposite in the vertical direction to the first hollow shell 18 and separated from the circuit board 12, as in Embodiment 1, the molding resin 16 will not directly contact the portion of the circuit board 12 located below the first hollow shell 18, thus avoiding adverse effects on the circuit board 12 caused by heat and pressure during the molding of the molding resin 16. As a result, deformation of the circuit board 12 during the molding of the molding resin 16 can be suppressed.

[0059] In Embodiment 1, as described above, the deformation suppression member is composed of a second hollow shell 24 having a second hollow portion 23. That is, the heat and pressure during the molding of the molding resin 16 act on the circuit board 12 via the deformation suppression member, but the aforementioned heat and pressure act not only through the second hollow shell 24 made of synthetic resin, but also through the second hollow portion 23, which is formed by air sealed inside the second hollow shell 24. Therefore, the influence of the heat and pressure during the molding of the molding resin 16 on the circuit board 12 can be further reduced, and deformation of the circuit board 12 can be more reliably prevented.

[0060] The first hollow portion 21 and the second hollow portion 23 are aligned in the projection along the thickness direction (vertical direction) of the circuit board 12. Specifically, in Embodiment 1, the first hollow shell 18 and the second hollow shell 24, which respectively constitute the first hollow portion 21 and the second hollow portion 23, are positioned to overlap in the vertical projection. This prevents deformation of the non-overlapping portions in the vertical projection due to heat and pressure during molding of the molding resin 16, for example, when one of the first hollow portion (first hollow shell) and the second hollow portion (second hollow shell) is larger than the other in the vertical projection. In summary, by positioning the first hollow portion 21 (first hollow shell 18) and the second hollow portion 23 (second hollow shell 24) to overlap in the vertical projection, deformation of the portion of the circuit board 12 sandwiched between the first hollow shell 18 and the second hollow shell 24 can be further reliably suppressed.

[0061] A FET 26, serving as a second electronic component, is mounted on the lower surface 22 of the circuit board 12. The FET 26 is covered by a second hollow housing 24 via a second hollow portion 23. That is, the FET 26, serving as a second electronic component, can be cleverly configured within the internal space (second hollow portion 23) of the second hollow housing 24, which functions as a deformation suppression member. As a result, not only the first electronic component (capacitor 14) but also the second electronic component (FET 26) can be mounted on the circuit board 12, providing a circuit unit 10 capable of performing more functions.

[0062] In particular, the protruding dimension of the first hollow housing 18 protruding from the upper surface 20 of the circuit board 12 is larger than the protruding dimension of the second hollow housing 24 protruding from the lower surface 22 of the circuit board 12. Therefore, a first electrical component (e.g., capacitor 14) with a vertical dimension larger than that of a second electronic component (e.g., FET 26) disposed in the second hollow housing 24 (second hollow housing 23) can be disposed inside the first hollow housing 18 (first hollow portion 21).

[0063] The first hollow housing 18 and the second hollow housing 24 are formed of a material having a glass transition temperature above the molding temperature of the molding resin 16. As a result, the heat and pressure during the molding of the molding resin 16 can be prevented from acting on the circuit board 12 through the first hollow housing 18 and the second hollow housing 24, and deformation of the circuit board 12 between the first hollow housing 18 and the second hollow housing 24 can be prevented more reliably.

[0064] <Implementation Method 2>

[0065] The following uses Figure 4The circuit unit 50 of Embodiment 2 of this disclosure will be described. The basic structure of the circuit unit 50 of Embodiment 2 is the same as that of the circuit unit 10 of Embodiment 1, but it is configured to also include a busbar 52. In Embodiment 2, for components and parts that are the same as those in Embodiment 1, detailed descriptions are omitted in the figures using the same reference numerals as in Embodiment 1.

[0066] like Figure 4 As shown, in Embodiment 2, capacitor 14 is mounted on busbar 52, and FET 26 is mounted on circuit board 12. Specifically, busbar 52 overlaps with the upper surface 20 of circuit board 12 via insulating sheet 54, and capacitor 14 is mounted on the upper surface of busbar 52. Thus, capacitor 14, serving as a first electronic component, is mounted on one side (upper surface 20) of circuit board 12. Furthermore, a first hollow housing 18 is overlapped and fixed (e.g., bonded) around capacitor 14 on the upper surface of busbar 52. Figure 4 In the image, the thickness of the FET26 is exaggerated for ease of understanding.

[0067] It should be noted that the busbar 52, for example, is a roughly rectangular flat plate shape when viewed from above. In Embodiment 2, the busbar 52 is formed to a size smaller than the circuit board 12. Additionally, the insulating sheet 54 is roughly rectangular when viewed from above and is formed to a size larger than the busbar 52. Therefore, the busbar 52 overlaps with the circuit board 12 through the insulating sheet 54, resulting in the circuit board 12 and the busbar 52 overlapping in a non-conductive state. Thus, conductive members (not shown) for individually supplying power extend from the circuit board 12 and the busbar 52. With the circuit unit 50 formed by molding the molding resin 16, the conductive members extending from the circuit board 12 and the busbar 52 are exposed on the outer surface of the molding resin 16.

[0068] Furthermore, the FET26 is mounted on the lower surface 22 of the circuit board 12 in the same manner as in Embodiment 1, and a second hollow housing 24, serving as a deformation suppression member, is fixed around the FET26 on the lower surface 22 of the circuit board 12. The first hollow housing 18 and the second hollow housing 24 have the same shape as in Embodiment 1, and are fixed at a position where they overlap when viewed from above, sandwiching the busbar 52 and the circuit board 12 on the upper and lower sides.

[0069] In Embodiment 2, with the structure described above, the basic structure is the same as in Embodiment 1, thus achieving the same effects as in Embodiment 1. Furthermore, in Embodiment 2, the capacitor 14 is mounted on the busbar 52. Therefore, when the capacitor 14 is energized and heats up, this heat is dissipated to the outside via the busbar 52, which is made of metal and has good thermal conductivity, and the molding resin 16 surrounding the busbar 52. Therefore, in Embodiment 2, the busbar 52 can also function as a heat sink. In particular, in Embodiment 2, since the insulating sheet 54 is thermally conductive, the heat generated when the FET 26 is energized is transferred to the busbar 52 via the circuit board 12 and the insulating sheet 54, thus dissipating heat not only from the capacitor 14 but also from the FET 26. Moreover, the melting point of the metal busbar 52 is higher than the molding temperature of the molding resin 16, so by overlapping with the circuit board 12, deformation of the circuit board 12 can be prevented, and it can also function as a deformation suppression member.

[0070] <Implementation Method 3>

[0071] The following uses Figure 5 The circuit unit 60 of Embodiment 3 of this disclosure will be described. The basic structure of the circuit unit 60 of Embodiment 3 is the same as that of the circuit unit 10 of Embodiment 1, but it is configured to further include a flexible printed circuit board (FPC) 62. A known flexible printed circuit board can be used as the FPC 62. In Embodiment 3, circuits (not shown) are printed on both the top and bottom surfaces of the FPC 62. It should be noted that... Figure 5 In the image, the thickness of FPC62 is exaggerated for ease of understanding.

[0072] like Figure 5 As shown, in Embodiment 3, capacitor 14 is mounted on FPC 62, and FET 26 is mounted on circuit board 12. Specifically, FPC 62 overlaps with the upper surface 20 of circuit board 12, and capacitor 14 is mounted on the upper surface of FPC 62. Thus, capacitor 14, serving as a first electronic component, is mounted on one side (upper surface 20) of circuit board 12. Furthermore, a first hollow housing 18 is overlapped and fixed (e.g., bonded) around capacitor 14 on the upper surface of FPC 62.

[0073] Furthermore, the FET26 is mounted on the lower surface 22 of the circuit board 12 in the same manner as in Embodiment 1, and a second hollow housing 24 serving as a deformation suppression member is fixed around the FET26 on the lower surface 22 of the circuit board 12. The FPC62, which overlaps each other in the vertical direction, is electrically connected to the circuit board 12 through circuits provided on their respective overlapping surfaces. A conductive member (not shown) for supplying power to the circuit board 12 and the FPC62 extends from at least one of the circuit board 12 and the FPC62. When the circuit unit 60 is formed by molding the molding resin 16, the conductive member is exposed on the outer surface of the molding resin 16. It should be noted that the FPC62 and the circuit board 12 may overlap with the insulating sheet 54 described in Embodiment 2, or they may not be electrically connected.

[0074] In addition, the first hollow housing 18 and the second hollow housing 24 have the same shape as in Embodiment 1. The first hollow housing 18 and the second hollow housing 24 are fixed on the upper and lower sides of the busbar 52 and the circuit board 12 at a position where they overlap when viewed from above.

[0075] In Embodiment 3, which has the same structure as Embodiment 1, the basic structure is the same, and thus the same effect as Embodiment 1 can be achieved. The second hollow housing 24, which serves as a deformation suppression member, can prevent the deformation of the circuit board 12 and the FPC 62.

[0076] <Implementation Method 4>

[0077] The following uses Figure 6 The circuit unit 70 of Embodiment 4 of this disclosure will be described. The basic structure of the circuit unit 70 of Embodiment 4 is the same as that of the circuit unit 10 of Embodiment 1, but as a deformation suppression member, it includes a plate member 72, which is mounted on the lower surface 22 side of the circuit board 12 and is arranged opposite to the first hollow portion 21 (first hollow shell 18) in such a way that the circuit board 12 is sandwiched in the middle.

[0078] The board member 72 can be formed from synthetic resin or metal, but if it is made of synthetic resin, it is preferable to form it from a material having a glass transition temperature above the molding temperature of the molding resin 16. Furthermore, the board member 72 is formed as a polygonal member including a circle, rectangle, etc., having an area equal to or larger than the first hollow shell 18 in a top view (projection in the vertical direction). The board member 72 is fixed (e.g., bonded) to the lower surface 22 of the circuit board 12 in such a way that the board member 72 completely overlaps with the first hollow shell 18 in the vertical projection, or that the interior of the first hollow shell 18 overlaps with the interior of the board member 72.

[0079] In Embodiment 4, which is configured as described above, the basic structure is the same as in Embodiment 1, and thus the same effect as in Embodiment 1 can be achieved. By using the plate member 72 as a deformation suppression member, deformation of the circuit board 12 can be prevented.

[0080] <Variation Example>

[0081] The above descriptions of embodiments 1 to 4 are specific examples of this disclosure, but this disclosure is not limited to these specific descriptions. Modifications and improvements within the scope of achieving the purpose of this disclosure are included in this disclosure. For example, the following modifications of the embodiments are also included in the technical scope of this disclosure.

[0082] (1) In Embodiment 1 described above, capacitor 14 and FET 26 are described as the first and second electronic components mounted on the circuit board 12. However, these are only examples, and the type and shape of the first and second electronic components are not limited. Known electronic components can be mounted. That is, in Embodiment 1, the vertical dimension of the first electronic component (capacitor 14) is larger than that of the second electronic component (FET 26), but the second electronic component can also be made larger, and the vertical dimension of the second hollow housing can be larger than that of the first hollow housing. The same applies to Embodiments 2 and 3, in which the first electronic component is mounted on the busbar and FPC.

[0083] (2) In the above embodiments, one electronic component is housed in a hollow housing (hollow portion), but multiple electronic components may also be housed in a hollow housing (hollow portion). Furthermore, when multiple electronic components are mounted on one side (e.g., the upper surface) of the circuit board, the multiple electronic components may be housed in a hollow housing as described above, or multiple electronic components may be housed individually in the same number of hollow housings. It should be noted that when multiple hollow housings (first hollow housings) are provided on one side (e.g., the upper surface) of the circuit board, hollow housings (second hollow housings) may also be provided on the other side (e.g., the lower surface) of the circuit board at the same position as the hollow housings (first hollow housings) on one side, or the board member described in Embodiment 4 may be configured as a whole of hollow housings (first hollow housings) covering one side.

[0084] (3) In embodiments 1 to 3 described above, the second electronic component (FET26) is disposed within the second hollow housing 24 (second hollow portion 23) and mounted on the lower surface 22 of the circuit board 12, but this is not a limitation. That is, the second electronic component may not be housed in the second hollow housing. It should be noted that when hollow housings are provided on both the upper and lower surfaces of the circuit board, the electronic component can be housed in at least one of the hollow housings. For example, the electronic component may be housed in the lower second hollow housing and not housed in the upper first hollow housing. In addition, in this case, the board member described in embodiment 4 may also be stacked on the upper surface of the circuit board.

[0085] (4) In the above embodiment, a busbar 52 smaller than the circuit board 12 is superimposed on the circuit board 12 with an insulating sheet 54 between them. However, the circuit boards and busbars can also be opposite, and a circuit board smaller than the busbar can be superimposed on the busbar with an insulating sheet between them.

[0086] (5) In Embodiment 1 described above, the first hollow shell 18 is formed of synthetic resin. However, as... Figure 7 As shown in the circuit unit 80, the first hollow housing 82 can also be formed of metal. In this case, the first hollow housing 82 can be fixed to the circuit board 12 by adhesive bonding or by soldering. When the first hollow housing 82 is fixed to the circuit board 12 by soldering, the first hollow housing 82 can be fixed to the circuit board 12 at the same time as the first electronic component (e.g., a capacitor) is mounted on the circuit board 12. Therefore, the bonding process required when the first hollow housing 82 is bonded to the circuit board 12 can be omitted, and the circuit unit 80 can be easily manufactured. The same applies in embodiments 2 to 4.

[0087] (6) In Embodiment 1 described above, the second hollow shell 24 is formed of synthetic resin. However, as... Figure 7 As shown in the circuit unit 80, the second hollow housing 84 can also be formed of metal. In this way, as described above, the same effect can be achieved as when the first hollow housing 82 is formed of metal. The same applies in Embodiment 2 or Embodiment 3. It should be noted that both the first hollow housing 82 and the second hollow housing 84 can be formed of metal, or only the first hollow housing 82 or only the second hollow housing 84 can be formed of metal.

[0088] Explanation of reference numerals in the attached figures

[0089] 10 circuit units (Implementation Method 1)

[0090] 12 circuit boards

[0091] 14. Capacitor (First Electronic Component)

[0092] 16 molding resin

[0093] 18. First hollow shell (shell)

[0094] 20. Top surface (one face)

[0095] 21 First Hollow Section

[0096] 22. Lower surface (the other surface)

[0097] 23 Second Hollow Section

[0098] 24 Second hollow shell (deformation suppression component)

[0099] 26 FET (Second Electronic Component)

[0100] 28 Upper bottom wall

[0101] 30 Last week's wall section

[0102] 34 flange-like portion

[0103] 36 bottom wall

[0104] 38 Next week wall section

[0105] 42 Flange-like portion

[0106] 50 circuit units (Implementation Method 2)

[0107] 52 Busbars (Deformation Suppression Components)

[0108] 54 insulating sheet

[0109] 60 circuit units (Implementation Method 3)

[0110] 62 FPC

[0111] 70 circuit units (Implementation Method 4)

[0112] 72 plate components

[0113] 80 circuit units ( Figure 7 )

[0114] 82 First Hollow Shell

[0115] 84 Second hollow shell.

Claims

1. A circuit unit comprising: Circuit board; A first electronic component is mounted on one side of the circuit board; A first hollow housing is mounted on one side of the circuit board, forming a first hollow portion around the first electronic component and covering the first electronic component; A deformation suppression member is mounted on the other side of the circuit board, and is configured opposite to the first hollow portion to suppress deformation of the circuit board by sandwiching the circuit board in the middle; and The circuit board, the first electronic component mounted on the circuit board, the first hollow shell and the deformation suppression member are embedded in the molding resin.

2. The circuit unit according to claim 1, wherein, The deformation suppression member includes a second hollow shell, which is mounted on the other side of the circuit board and is configured to sandwich the circuit board in the middle, thus being opposite to the first hollow portion.

3. The circuit unit according to claim 2, wherein, The first hollow portion and the second hollow portion are aligned in the projection of the circuit board along its thickness direction.

4. The circuit unit according to claim 2 or 3, wherein, The circuit unit further includes a second electronic component, which is mounted on the other side of the circuit substrate. The second electronic component is covered by the second hollow shell via the second hollow portion.

5. The circuit unit according to claim 2 or 3, wherein, The protrusion of the second hollow housing from the other side of the circuit board is smaller than the protrusion of the first hollow housing from one side of the circuit board.

6. The circuit unit according to claim 2 or 3, wherein, The first hollow shell and the second hollow shell are formed of a material having a glass transition temperature above the molding temperature of the molding resin.

7. The circuit unit according to claim 2 or 3, wherein, At least one of the first hollow shell and the second hollow shell is formed of metal.

8. The circuit unit according to claim 1, wherein, The deformation suppression member includes a plate member mounted on the other side of the circuit board, arranged opposite to the first hollow portion in a manner that sandwiches the circuit board in the middle. The plate component is formed of a material having a glass transition temperature above the molding temperature of the molding resin.

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