Electronic device

Abstract

To provide an electronic device capable of suppressing a decrease in connection reliability while reducing a thermal resistance.SOLUTION: A printed circuit board 20 has a through hole 23. An electronic component 30 is disposed on a one surface 21 of the printed circuit board 20. A cooler 50 is disposed to face the one surface 21. A TIM 60 is interposed between the electronic component 30 and the cooler 50, and thermally connects the electronic component 30 and the cooler 50. A back plate 70 is disposed on a back surface 22 of the printed circuit board 20 and is fixed to the cooler 50 through the through hole 23. The back plate is provided so as to overlap at least a part of the electronic component 30 in a plan view, and has a main body part 71 disposed in contact with the back surface 22, and a plurality of leg parts 72 provided away from the back surface 22. A fixing part 90 between each leg part 72 and the cooler 50 is inserted through the through hole 23 and is not in contact with the printed circuit board 20.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] TECHNICAL FIELD The disclosure herein relates to electronic devices. [Background technology]

[0002] Patent Document 1 discloses an electronic device including a cooler, a printed circuit board, electronic components, a heat-conducting member, and a backplate. The contents of the prior art document are incorporated by reference as explanations of the technical elements in this specification. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] International Publication No. 2022 / 192031 Summary of the Invention [Problem to be solved by the invention]

[0004] In Patent Document 1, a thermally conductive member is interposed between a cooler and electronic components arranged on one side of a printed circuit board. A backplate is also arranged on the backside of the printed circuit board. This configuration allows the backplate to apply a load to the printed circuit board from the backside, compressing the thermally conductive member and reducing thermal resistance. However, since the backplate is fixed to the cooler via the printed circuit board, distortion occurs around the fixed portion of the printed circuit board, which reduces the connection reliability of the electronic components. Further improvements are needed in electronic devices, both in terms of the above and other aspects not mentioned.

[0005] An object of the present disclosure is to provide an electronic device that can reduce thermal resistance while suppressing a decrease in connection reliability. [Means for solving the problem]

[0006] An electronic device according to one aspect of the disclosure includes: a printed circuit board (20) having one surface (21), a back surface (22) opposite to the one surface in the thickness direction, and through holes (23) opening in the one surface and the back surface; an electronic component (30) disposed on one surface at a position not overlapping with the through hole in a plan view in the plate thickness direction; a cooler (50) disposed opposite one surface; a heat conducting member (60) interposed between the electronic component and the cooler and thermally connecting the electronic component and the cooler; a back plate (70) disposed on the rear surface and fixed to the cooler through a through hole; Equipped with The back plate has a main body portion (71) arranged to overlap at least a part of the electronic component in a plan view and in contact with the rear surface, and a plurality of leg portions (72) connected to the main body portion and spaced apart from the rear surface, The fixing portion (90) between the leg portion of the back plate and the cooler passes through the through hole and does not contact the printed circuit board.

[0007] According to the disclosed electronic device, the main body of the backplate contacts the rear surface of the printed circuit board at a position overlapping at least a portion of the electronic component. This compresses the thermal conductive member and reduces thermal resistance. Furthermore, the legs of the backplate are spaced apart from the rear surface, and the fixing portions pass through the through holes and do not contact the printed circuit board. This prevents stress caused by fixing the legs to the cooler from acting on the mounting portion of the electronic component. This reduces thermal resistance while suppressing a decrease in connection reliability.

[0008] The various aspects disclosed in this specification employ different technical means to achieve their respective objectives. The reference numerals in parentheses in the claims and in this section are intended to exemplify correspondences with the following embodiments and are not intended to limit the technical scope. The objectives, features, and advantages disclosed in this specification will become more apparent by reference to the following detailed description and the accompanying drawings. [Brief explanation of the drawings]

[0009] [Figure 1] 1 is a cross-sectional view showing an electronic device according to a first embodiment. [Figure 2] FIG. 2 is a plan view seen from the Z1 direction shown in FIG. [Figure 3] FIG. 10 is a cross-sectional view showing a reference example. [Figure 4] FIG. 10 is a cross-sectional view showing a reference example. [Figure 5] FIG. 10 is a cross-sectional view showing a modified example. [Figure 6] FIG. 10 is a cross-sectional view showing a modified example. [Figure 7] FIG. 10 is a cross-sectional view showing a modified example. [Figure 8] FIG. 10 is a cross-sectional view showing a modified example. [Figure 9] FIG. 10 is a cross-sectional view showing an electronic device according to a second embodiment. [Figure 10] 10 is a plan view seen from the Z2 direction shown in FIG. 9. FIG. [Figure 11] FIG. 10 is a cross-sectional view showing an electronic device according to a third embodiment. [Figure 12] FIG. 10 is a cross-sectional view showing an electronic device according to a fourth embodiment. [Figure 13] FIG. 10 is a cross-sectional view showing an electronic device according to a fifth embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0010] Hereinafter, several embodiments will be described with reference to the drawings. Note that in each embodiment, corresponding components are designated by the same reference numerals, and redundant description may be omitted. When only a portion of the configuration is described in each embodiment, the configuration of another embodiment previously described may be applied to the remaining portion of the configuration. Furthermore, in addition to the combinations of configurations explicitly stated in the description of each embodiment, configurations of several embodiments may be partially combined together even if not explicitly stated, provided that there is no particular problem with the combination.

[0011] (First embodiment) First, a schematic configuration of the electronic device will be described. The electronic device is sometimes called an electronic control unit (ECU). ECU is an abbreviation for Electronic Control Unit. The electronic device may be mounted on, for example, a moving object. The moving object may be, for example, a vehicle, an aircraft, a ship, a construction machine, an agricultural machine, or the like. As an example, the electronic device of this embodiment is mounted on a vehicle.

[0012] <Electronic equipment> FIG. 1 is a cross-sectional view showing an example of an electronic device. FIG. 1 shows a part of the electronic device, particularly the periphery of an electronic component with a heat conductive member interposed between it and a cooler. FIG. 1 is a cross-sectional view taken along line II in FIG. 2. FIG. 2 is a plan view seen from the Z1 direction shown in FIG. 1. FIG. 2 shows the shapes of the electronic component and backplate, and the positional relationship between the electronic component and the backplate. The printed circuit board and the electronic component on the back side are omitted from FIG. 2.

[0013] In the following, the thickness direction of a printed circuit board is referred to as the Z direction. The direction perpendicular to the Z direction is referred to as the X direction, and the direction perpendicular to both the Z direction and the X direction is referred to as the Y direction. Unless otherwise specified, the shape viewed from the Z direction, in other words, the shape along the XY plane defined by the X and Y directions, is referred to as the planar shape. The planar view from the Z direction is sometimes simply referred to as the planar view.

[0014] As shown in Figures 1 and 2, the electronic device 10 includes a printed circuit board 20, electronic components 30 and 40, a cooler 50, a TIM 60, a backplate 70, and screws 80. The printed circuit board 20 may also be referred to as a board, a wiring board, a printed wiring board, etc. The printed circuit board 20 has one surface 21 and a back surface 22. The back surface 22 is the surface opposite to the one surface 21 in the Z direction, which is the thickness direction of the printed circuit board 20. The planar shape of the printed circuit board 20 is not particularly limited. As an example, the printed circuit board 20 of this embodiment has a substantially rectangular planar shape. The printed circuit board 20 is fixed to a housing. The printed circuit board 20 may also be fixed to a cooler 50 that forms part of the housing.

[0015] The printed circuit board 20 has an insulating base material and a conductor. The insulating base material is formed using an electrically insulating material such as resin. The insulating base material may contain only resin, or may be a combination of glass cloth, nonwoven fabric, or resin. The conductor is formed using a metal material with good conductivity such as Cu. The conductor includes wiring. The wiring may be referred to as a wiring layer, wiring pattern, conductor pattern, or the like.

[0016] The wiring may be formed, for example, by patterning a metal foil or by printing. At least a portion of the conductors, together with electronic components mounted on the printed circuit board 20, constitute a circuit. For this reason, the printed circuit board 20 on which electronic components are mounted is sometimes called a circuit board.

[0017] The wiring includes at least surface wiring arranged on the surface layer on the one surface 21 side of the insulating substrate. The wiring may include surface wiring arranged on the surface layer on the back surface 22 side, or may include inner layer wiring arranged inside the insulating substrate. In other words, the printed circuit board 20 may be a single-layer board, a double-sided board, or a multilayer board. As an example, the printed circuit board 20 of this embodiment is a multilayer board including inner layer wiring. The printed circuit board 20 has lands (not shown) that are electrode portions of the wiring on the surface layers of the one surface 21 and the back surface 22.

[0018] The conductors may include via conductors or through-hole lands in addition to wiring. Via conductors are formed by arranging a conductor such as plating in a through-hole (via) formed in an insulating layer that constitutes an insulating substrate. The via conductors electrically connect, for example, wiring arranged on different layers. The through-hole lands are formed on the wall surfaces of through-holes that penetrate the printed circuit board 20 in the Z direction. The conductors may also include conductors that do not provide a circuit function (wiring function), for example, conductors for heat dissipation.

[0019] The printed circuit board 20 has a through hole 23. The through hole 23 penetrates the printed circuit board 20. The through hole 23 extends in the Z direction and is open to the one surface 21 and the back surface 22. The through hole 23 is a hole for fixing the back plate 70 to the cooler 50. The diameter of the through hole 23 is larger than the outer diameter of the screw receiving portion 52 of the cooler 50. The diameter of the through hole 23 is a length that ensures a non-contact state with the screw receiving portion 52 even if manufacturing variations and assembly variations occur.

[0020] A plurality of electronic components are mounted on the printed circuit board 20. The plurality of electronic components, together with the conductors of the printed circuit board 20, provide a circuit. The electronic components are soldered to corresponding lands. The electronic components include electronic components 30 and 40. Electronic component 30 is mounted on one surface 21 of the printed circuit board 20 facing the cooler 50. Electronic component 30 is a heat-generating component with TIM 60 interposed between it and the cooler 50. The heat-generating component is an electronic component that generates a large amount of heat among the plurality of electronic components mounted on the printed circuit board 20. Electronic component 30 is positioned so as not to overlap with through-hole 23 in a plan view.

[0021] The electronic component 30 is a surface-mount electronic component, such as a non-leaded package such as BGA, QFN, or SON. BGA is an abbreviation for Ball Grid Array. QFN is an abbreviation for Quad Flat Non-leaded package. SON is an abbreviation for Small Outline Non-leaded package. As an example, the electronic component 30 of this embodiment is a BGA-type electronic component. A BGA-type electronic component may be provided with a lid for heat dissipation, or may be configured without a lid.

[0022] The electronic component 30 includes a semiconductor chip 31, a rewiring substrate 32, a lid 33, solder 34, and a sealing resin body 35. The semiconductor chip 31 is sometimes called an IC chip. The semiconductor chip 31 is, for example, an SoC. SoC is an abbreviation for System on a Chip. The rewiring substrate 32 is sometimes called an interposer. The rewiring substrate 32 is formed by disposing rewiring on an insulating base material. The rewiring is electrically connected to the terminals of the semiconductor chip 31. The rewiring substrate 32 has a generally rectangular shape in plan view. The semiconductor chip 31 is disposed in the central region of the rewiring substrate 32.

[0023] The lid 33 may also be referred to as a lid member, a cover, a heat dissipation member, etc. The lid 33 is formed using a metal material with excellent thermal conductivity, such as Cu. The lid 33 is interposed between the top surface of the semiconductor chip 31 and the cooler 50 in the Z direction. The lid 33, together with the TIM 60, transfers heat generated by the semiconductor chip 31 to the cooler 50.

[0024] The lid 33 is disposed on the mounting surface side of the rewiring substrate 32 on which the semiconductor chip 31 is mounted. The lid 33 is provided so as to overlap at least a portion of the semiconductor chip 31 in a plan view, for example, and preferably so as to enclose the semiconductor chip 31. The lid 33 covers the semiconductor chip 31. The lid 33 is solder-bonded to the rewiring substrate 32.

[0025] The solder 34 is ball-shaped. The solder 34 is sometimes referred to as a solder ball. The solder 34 is arranged on the surface of the rewiring substrate 32 opposite to the surface on which the semiconductor chip 31 is mounted. The solder 34 is electrically connected to the rewiring. The plurality of solders 34 are arranged in a matrix. The solder 34 is bonded to lands (not shown) provided on one surface 21 of the printed circuit board 20.

[0026] The electronic component 40 is mounted on the rear surface 22 of the printed circuit board 20. The electronic component 40 is arranged at a position overlapping the electronic component 30 in a plan view. The electronic component 40 is a component that stabilizes the operation of the electronic component 30. As an example, the electronic component 40 in this embodiment is a bypass capacitor. The bypass capacitor suppresses, for example, fluctuations in the power supply voltage supplied to the electronic component 30. The bypass capacitor suppresses, for example, the inflow of noise to the electronic component 30 and / or the outflow of noise from the electronic component 30. A plurality of electronic components 40 are mounted on the rear surface 22. The plurality of electronic components 40 are arranged within an area surrounded by a frame-shaped main body 71.

[0027] The cooler 50 cools at least some of the multiple electronic components mounted on the printed circuit board 20. The cooler 50 cools heat-generating components including the electronic components 30. The cooling method of the cooler 50 is not particularly limited. The electronic device 10 may be provided with a housing separate from the cooler 50, or the cooler 50 may form part of the housing. A part of the housing may form the cooler 50.

[0028] As an example, the cooler 50 of this embodiment is a water-cooled type. The cooler 50 forms part of a housing (case) that houses the printed circuit board 20 and the electronic components 30 and 40. For convenience, only a part of the housing is shown in FIG. 1. The cooler 50 is made of a metal material such as aluminum. The cooler 50 has a cooler main body 51 and a screw receiving portion 52.

[0029] The cooler body 51 is disposed opposite one surface 21 of the printed circuit board 20. A flow path 511 is formed in the cooler body 51. The flow path 511 is provided so as to overlap at least the heat-generating components in a plan view in order to effectively cool the heat-generating components. The flow path 511 extends in a predetermined direction perpendicular to the Z direction.

[0030] An inlet pipe and an outlet pipe (not shown) are connected to the flow path 511. The refrigerant 512 introduced from the inlet pipe flows through the flow path 511 and is discharged through the outlet pipe. As the refrigerant 512, for example, a refrigerant that changes phase, such as water or ammonia, or a refrigerant that does not change phase, such as an ethylene glycol-based refrigerant, can be used. The cooler main body 51 may have fins that protrude into the flow path 511. The presence of fins increases the contact area with the refrigerant 512, improving heat exchange with the refrigerant 512, i.e., cooling efficiency.

[0031] The screw receiving portion 52 is connected to the cooler body 51 and protrudes from the cooler body 51 toward the printed circuit board 20. The screw receiving portion 52 may be made of the same material as the cooler body 51 and be connected to it as an integral part. The screw receiving portion 52 may be, for example, a part of a molded body. The screw receiving portion 52 may be connected to the cooler body 51 by, for example, joining. The screw receiving portion 52 extends in the Z direction.

[0032] The cooler 50 has screw holes 53 that open at the protruding tips of the screw receiving portions 52. The screw holes 53 are provided to correspond to the screws 80 that fix the back plate 70 to the cooler 50. The screws 80 are threaded into the screw holes 53. The cooler 50 has a number of screw receiving portions 52 that corresponds to the number of leg portions 72 of the back plate 70.

[0033] As an example, the cooler 50 of this embodiment has four screw receiving portions 52. The screw receiving portions 52 are inserted through the through holes 23 of the printed circuit board 20 and protrude toward the rear surface 22. The screw receiving portions 52 are not in contact with the wall surfaces of the through holes 23.

[0034] The TIM 60 is a thermally conductive material such as a heat dissipation gel or a thermally conductive sheet. TIM is an abbreviation for Thermal Interface Material. The TIM 60 is interposed between the electronic component 30 and the cooler 50. The TIM 60 is provided at a position overlapping the electronic component 30, particularly the semiconductor chip 31, in a plan view. The TIM 60 thermally connects the electronic component 30 and the cooler 50.

[0035] As an example, the TIM 60 of this embodiment includes TIMs 61 and 62. The TIM 61 is interposed between the top surface of the semiconductor chip 31 and the lid 33, and thermally connects the semiconductor chip 31 and the lid 33. The TIM 62 is interposed between the lid 33 and the cooler 50 (cooler body 51), and thermally connects the lid 33 and the cooler 50. The TIM 62 is provided so as to enclose the TIM 61 in a plan view.

[0036] The backplate 70 presses the printed circuit board 20 against the cooler body 51 of the cooler 50. The backplate 70 presses the electronic component 30 against the cooler 50. The backplate 70 has spring properties, and presses the printed circuit board 20 against the cooler 50 by the reaction force caused by spring deformation. The backplate 70 is disposed on the rear surface 22 side of the printed circuit board 20.

[0037] The backplate 70 has a main body 71 and a plurality of leg portions 72. The main body 71 is provided so as to overlap at least a portion of the electronic component 30 in a plan view. The main body 71 is arranged in contact with the rear surface 22 when the backplate 70 is fixed to the cooler 50. The leg portions 72 are continuous with the main body 71. When the backplate 70 is fixed to the cooler 50, at least a portion of the leg portions 72 is arranged away from the rear surface 22. For stable fixation, it is preferable that the number of leg portions 72 is three or more.

[0038] As an example, the main body 71 of this embodiment has a frame shape. The main body 71 has a substantially rectangular ring shape in a plan view. The main body 71 is provided so as to overlap the outer peripheral region of the rewiring substrate 32 in a plan view. The main body 71 is provided so as to surround the semiconductor chip 31 in a plan view. The leg portions 72 extend from the four corners of the main body 71. The backplate 70 has four leg portions 72. The backplate 70 has bending portions at the boundary position between the main body 71 and the leg portions 72 and at intermediate positions of the leg portions 72. The leg portions 72 are provided so as to be spring-deformable in the Z direction. The leg portions 72 are arranged away from the rear surface 22 over almost their entire length.

[0039] The end of the leg portion 72 is provided with a hole 73 for fixing the screw 80 to the screw receiving portion 52. The distance between the end of two adjacent leg portions 72 along the outer periphery of the rewiring board 32 is wider than the distance between the connecting ends with the main body portion 71. The leg portions 72 extend obliquely from the main body portion 71. When fastened with the screws, the spring reaction force of the leg portions 72 causes the main body portion 71 to press the printed circuit board 20, and therefore the electronic component 30, against the cooler 50. In the example shown in FIG. 1 , the leg portions 72 are not in contact with the screw receiving portion 52 when fastened with the screws, but the leg portions 72 may also be configured to contact the protruding tip surface of the screw receiving portion 52.

[0040] The fixing portion 90 between the leg portion 72 and the cooler 50 is inserted through the through hole 23 of the printed circuit board 20. The fixing portion 90 is not in contact with the printed circuit board 20. As an example, the fixing portion 90 in this embodiment includes a screw 80 and a screw receiving portion 52. The screw 80 is inserted through a hole 73 provided in the leg portion 72 and is screwed into the corresponding screw hole 53.

[0041] <Summary of the First Embodiment> 3 and 4 are cross-sectional views showing a reference example. In the reference example, the reference symbols of elements related to this embodiment are given the suffix "r." FIGS. 3 and 4 correspond to FIG. 1. In FIGS. 3 and 4, components equivalent to electronic component 40 are omitted.

[0042] The electronic device 10r shown in FIG. 3 does not include a backplate. A cooler 50r has a support portion 52r extending from a cooler main body 51r toward a printed circuit board 20r. The support portion 52r supports the printed circuit board 20r. A screw hole (not shown) is formed in the support portion 52r. A screw 80r is inserted through a through hole 23r in the printed circuit board 20r and threaded into the screw hole. The head of the screw 80r and the support portion 52r hold the printed circuit board 20r between them.

[0043] In the configuration shown in Figure 3, the printed circuit board 20r is pressed against the cooler 50r by the screws 80r. Because the printed circuit board 20r is pressed against the cooler 50r at a position outside the electronic component 30r in a plan view, the TIM 60r cannot be sufficiently compressed. In other words, the thermal resistance cannot be reduced. Furthermore, the printed circuit board 20r bends as shown by the dashed line.

[0044] The electronic device 10r shown in FIG. 4 includes a backplate 70r. The backplate 70r has a frame-shaped main body and four legs. The legs extend from the main body in the same plane. Screws 80r are inserted through holes in the legs and through holes 23r and are threaded into screw holes in a support portion 52r. The heads of the screws 80r and the support portion 52r hold the backplate 70r and the printed circuit board 20r in a sandwiched position.

[0045] In the configuration shown in FIG. 4, the backplate 70r is positioned so as to overlap the electronic component 30r in a plan view. This compresses the TIM 60r and reduces thermal resistance. The backplate 70r suppresses deflection of the printed circuit board 20r. However, because the heads of the screws 80r sandwich the printed circuit board 20r between the legs of the backplate 70r and the support parts 52r, tightening the screws causes distortion in the printed circuit board 20r. In other words, stress caused by tightening the screws acts on the solder joints of the electronic component 30r, reducing connection reliability.

[0046] According to the electronic device 10 of this embodiment, the main body 71 of the backplate 70 contacts the rear surface 22 of the printed circuit board 20 at a position overlapping at least a portion of the electronic component 30. Therefore, the load of the backplate 70 compresses the TIM 60 (thermal conductive material), reducing thermal resistance. Furthermore, the legs 72 of the backplate 70 are spaced apart from the rear surface 22, and the fixing portions 90 pass through the through holes 23 and are not in contact with the printed circuit board 20. As a result, stress caused by fixing the legs 72 of the backplate 70 to the cooler 50 does not act on the solder joints (mounting portions) of the electronic component 30. Therefore, it is possible to reduce thermal resistance while suppressing a decrease in connection reliability.

[0047] As illustrated, the fixing portion 90 may include a screw 80 and a screw receiving portion 52. The screw receiving portion 52 protrudes from the cooler main body 51 toward the printed circuit board 20 and has a screw hole 53 into which the screw 80 is screwed. The screw 80 is inserted through a hole 73 provided in the leg portion 72 and screwed into the screw hole 53. The fixing portion 90 fixes the backplate 70 to the cooler 50 without contacting the printed circuit board 20. Therefore, it is possible to reduce thermal resistance and prevent stress caused by screw fastening from acting on the solder joints of the electronic component 30.

[0048] As shown in the example, the screw receiving portion 52 may be configured to pass through the through hole 23 and protrude toward the rear surface 22. The screw receiving portion 52 passes through the through hole 23 without contacting the printed circuit board 20. This makes it possible to reduce thermal resistance and prevent a decrease in connection reliability. Furthermore, because the screw receiving portion 52 protrudes toward the rear surface 22, the length of the screw 80 can be shortened, allowing for more stable fastening.

[0049] As illustrated, the main body 71 may be frame-shaped so as to overlap the outer peripheral region of the electronic component 30 in a plan view. This allows the TIM 60 to be compressed while suppressing deformation (warping) of the printed circuit board 20 with a small load. In particular, a bypass capacitor may be mounted as the electronic component 40 within the region surrounded by the frame-shaped main body 71 on the rear surface 22. By employing the frame-shaped main body 71 and intentionally providing a mountable region, the electronic component 40 (bypass capacitor) can be mounted near the electronic component 30. For example, fluctuations in the power supply voltage supplied to the electronic component 30 can be suppressed. For example, the inflow of noise to the electronic component 30 and / or the outflow of noise from the electronic component 30 can be suppressed.

[0050] As illustrated, a BGA-type electronic component having a heat dissipation lid 33 may be used as the electronic component 30. According to the above configuration, the TIM 61 interposed between the semiconductor chip 31 and the lid 33 and the TIM 62 acting as a base material between the lid 33 and the cooler 50 can be compressed.

[0051] <Modification> Although the electronic component 30 has been exemplified as having a single semiconductor chip 31, this is not limiting. The electronic component 30 may have multiple semiconductor chips. For example, as shown in FIG. 5, a multi-chip module may be adopted as the electronic component 30. The electronic component 30 has multiple semiconductor chips 31. The semiconductor chip 31 includes semiconductor chips 31A and 31B. The rewiring substrate 32 includes a main substrate 321 and multiple sub-substrates 322. The solder 34 includes solder 341 provided on the surface of the main substrate 321 facing the printed circuit board 20 and solder 342 provided on the surface of the sub-substrate 322 facing the printed circuit board 20.

[0052] A semiconductor chip 31A is mounted on one of the sub-substrates 322, and a semiconductor chip 31B is mounted on the other of the sub-substrates 322. The sub-substrates 322 are mounted on the main substrate 321. A lid 33 is mounted on each of the sub-substrates 322 so as to cover the corresponding semiconductor chip 31A, 31B. TIMs 61 are individually disposed between the semiconductor chip 31A and the lid 33, and between the semiconductor chip 31B and the lid 33. TIMs 62 are individually disposed between the lid 33 on the semiconductor chip 31A side and the cooler 50, and between the lid 33 on the semiconductor chip 31B side and the cooler 50.

[0053] 5, two BGA-type electronic components each having a lid 33 are mounted on the main substrate 321, but this is not limiting. The number of BGA-type electronic components each having a lid 33 mounted on the main substrate 321 may be one, or may be three or more. The electronic component 30 may include electronic components of other structures in addition to the BGA-type electronic component each having a lid 33.

[0054] As shown in Fig. 6, a chiplet may be adopted as the electronic component 30. The electronic component 30 has a plurality of semiconductor chips 31. The plurality of semiconductor chips 31 are mounted on a common (single) rewiring substrate 32. The plurality of semiconductor chips 31 are encapsulated by an encapsulating resin body 35. A TIM 60 is interposed between the top surface of the electronic component 30 and the cooler 50, and thermally connects the top surface of the electronic component 30 and the cooler 50.

[0055] The structure of the cooler 50 is not limited to the example shown in Fig. 1. For example, as shown in Fig. 7, a heat sink may be used as the cooler body 51. A heat sink may also be called a heat sink or a cooling plate. As shown in Fig. 7, the cooler 50 may have a plurality of fins 54. The fins 54 are connected to the surface of the cooler body 51 opposite to the surface that contacts the TIM 60.

[0056] The structure of the leg portion 72 is not limited to the example shown in FIG. 1. The leg portion 72 may have a structure that allows spring deformation in the Z direction. For example, as shown in FIG. 8, the leg portion 72 may have a substantially S-shaped leaf spring structure. The leg portion 72 has a folded structure that extends in the Z direction. Furthermore, the leg portion 72 may be spaced apart from the rear surface 22 over its entire length. The base portion of the leg portion 72 that connects to the main body portion 71 may be in contact with the rear surface 22, and the portion beyond the base may be spaced apart from the rear surface 22.

[0057] (Second embodiment) This embodiment is a modification based on the previous embodiment, and the description of the previous embodiment can be used. In the previous embodiment, the main body 71 of the back plate 70 is frame-shaped. Alternatively, the main body 71 may have a shape other than the frame shape.

[0058] Fig. 9 is a cross-sectional view showing an example of an electronic device according to a second embodiment. Fig. 9 corresponds to Fig. 1. Fig. 9 is a cross-sectional view taken along line IX-IX in Fig. 10. Fig. 10 is a plan view seen from the Z2 direction shown in Fig. 9. Fig. 10 corresponds to Fig. 2. Fig. 10 shows the shapes of the electronic components and the backplate, and the positional relationship between the electronic components and the backplate.

[0059] 9 and 10, the backplate 70 has a main body portion 71 and leg portions 72. The main body portion 71 is solid in plan view. The main body portion 71 is provided so as to encompass the entire area where the solder 34 is to be disposed. The main body portion 71 may be provided so as to overlap most of the electronic component 30 in plan view, or may be provided so as to encompass the entire electronic component 30.

[0060] As an example, the main body 71 of this embodiment has a generally rectangular shape in plan view. The main body 71 encompasses the entire area of the rewiring substrate 32 where the solder 34 is arranged. The main body 71 is provided so as to overlap most of the electronic component 30 in a plan view. The leg portions 72 are connected to the four corners of the main body 71. The other configurations are the same as those described in the preceding embodiment.

[0061] <Summary of the second embodiment> As shown in the example, the main body 71 may be provided so as to encompass the entire area where the solder 34 is arranged in a plan view. The main body 71 may also be provided so as to overlap most of the electronic component 30. As with the configurations shown in the preceding embodiments, this configuration can reduce thermal resistance while suppressing a decrease in connection reliability. In particular, it can reduce unevenness in the load applied to the TIM 60 within the plane, effectively compressing the entire TIM 60.

[0062] (Third embodiment) This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be used. In the preceding embodiment, the screw receiving portion 52 is inserted through the through hole 23 and protrudes toward the rear surface 22. Alternatively, the screw receiving portion 52 may be configured not to be inserted into the through hole 23.

[0063] Fig. 11 is a cross-sectional view showing an example of an electronic device according to the third embodiment. Fig. 11 corresponds to Fig. 1. As shown in Fig. 11, the cooler 50 has a cooler main body 51 and a screw receiving portion 52. The screw receiving portion 52 extends in the Z direction from the cooler main body 51. When the back plate 70 is fixed to the cooler 50, the protruding tip of the screw receiving portion 52 is located above the one surface 21, that is, on the cooler main body 51 side. The screw receiving portion 52 is not inserted into the through hole 23.

[0064] The screw 80 is inserted through the hole 73 located above the rear surface 22. The screw 80 is inserted through the through hole 23 without contacting the wall surface of the through hole 23. The diameter of the through hole 23 is larger than the outer diameter of the screw 80. The diameter of the through hole 23 is long enough to ensure a non-contact state with the screw 80 even if manufacturing variations or assembly variations occur. The screw 80 is inserted through the hole 73 and the through hole 23 and protrudes toward the one surface 21. The screw 80 is threaded into the threaded hole 53 of the screw receiving portion 52 located on the one surface 21 side. The other configurations are the same as those described in the preceding embodiment.

[0065] <Summary of the third embodiment> As illustrated, the screw receiving portion 52 may not be inserted into the through hole 23, but the screw 80 may pass through the through hole 23 and protrude toward the one surface 21. As with the configuration shown in the preceding embodiment, it is possible to reduce thermal resistance while suppressing a decrease in connection reliability. In particular, it is possible to reduce the protruding height of the screw receiving portion 52 relative to the cooler body 51. Therefore, in a configuration in which the cooler body 51 and the screw receiving portion 52 are molded integrally, it is possible to simplify the structure of the molding die, for example. It is also possible to reduce manufacturing costs. Note that in the configuration shown in FIG. 11, the back plate 70 having the structure shown in the second embodiment may be employed.

[0066] (Fourth embodiment) This embodiment is a modification based on the preceding embodiment, and the description of the preceding embodiment can be used. In the preceding embodiment, the cooler 50 has the screw receiving portion 52. Alternatively, the cooler 50 may be configured without the screw receiving portion 52.

[0067] Fig. 12 is a cross-sectional view showing an example of an electronic device according to the fourth embodiment. Fig. 12 corresponds to Fig. 1. As shown in Fig. 12, a cooler 50 has a cooler main body 51. The cooler 50 does not have a screw receiving portion 52. The cooler main body 51 is provided with a screw hole 53 that opens into a surface facing the printed circuit board 20.

[0068] The screw 80 is inserted through the hole 73 located above the rear surface 22. The screw 80 is inserted through the through hole 23 without contacting the wall surface of the through hole 23. The diameter of the through hole 23 is larger than the outer diameter of the screw 80. The diameter of the through hole 23 is long enough to ensure a non-contact state with the screw 80 even if manufacturing variations or assembly variations occur. The screw 80 is inserted through the hole 73 and the through hole 23 and protrudes toward the one surface 21. The screw 80 is threaded into the threaded hole 53 of the cooler body 51. The other configurations are the same as those described in the preceding embodiment.

[0069] <Summary of the Fourth Embodiment> As illustrated, the screw 80 may be inserted through the hole 73 and the through-hole 23 and screwed into the screw hole 53 of the cooler body 51. As with the configuration shown in the preceding embodiment, it is possible to reduce thermal resistance while suppressing a decrease in connection reliability. In particular, since the screw receiving portion 52 can be eliminated, it is possible to simplify the configuration of the cooler 50. For example, it is possible to reduce manufacturing costs. Note that in the configuration shown in FIG. 12, the back plate 70 having the structure shown in the second embodiment may be adopted.

[0070] (Fifth embodiment) This embodiment is a modification based on the previous embodiment, and the description of the previous embodiment can be used. In the previous embodiment, the back plate 70 is fixed to the cooler 50 by screw fastening. Instead of this, a fixing means other than screw fastening may be used.

[0071] FIG. 13 is a cross-sectional view showing an example of an electronic device according to the fifth embodiment. FIG. 13 corresponds to FIG. 1. As shown in FIG. 13, a cooler 50 has a cooler main body 51 and a protruding portion 55. The protruding portion 55 is connected to the cooler main body 51 and protrudes from the cooler main body 51 toward the printed circuit board 20. The protruding portion 55 may be made of the same material as the cooler main body 51 and be integrally connected thereto. The protruding portion 55 may be, for example, a part of a molded body. The protruding portion 55 may be connected to the cooler main body 51 by, for example, joining. The protruding portion 55 extends in the Z direction.

[0072] The protrusion 55 passes through the through hole 23 and protrudes toward the back surface 22. The diameter of the through hole 23 is larger than the outer diameter of the protrusion 55. The diameter of the through hole 23 is long enough to ensure a non-contact state with the protrusion 55 even if manufacturing variations or assembly variations occur. The protrusion 55 is engaged with the back plate 70 while passing through the hole 73 of the leg 72. The protruding tip of the protrusion 55 is engaged with the surrounding portion of the hole 73 by a snap fit structure, a crimping structure, or the like. The fixing portion 90 includes the protrusion 55. The other configurations are the same as those described in the preceding embodiment.

[0073] <Summary of the Fifth Embodiment> As illustrated, the cooler 50 may be provided with a protrusion 55 that protrudes from the cooler body 51 toward the printed circuit board 20 and engages with the back plate 70 while passing through the hole 73. The fixing portion 90 may also be configured to include the protrusion 55. As with the configuration shown in the preceding embodiment, this can reduce thermal resistance while suppressing a decrease in connection reliability. In particular, since the screws 80, which are separate components, can be eliminated, the number of parts can be reduced. Note that the back plate 70 having the structure shown in the second embodiment may be adopted in the configuration shown in FIG. 13.

[0074] (Other embodiments) The disclosure in this specification and drawings, etc. is not limited to the exemplified embodiments. The disclosure encompasses the exemplified embodiments and modifications thereto by those skilled in the art. For example, the disclosure is not limited to the combinations of parts and / or elements shown in the embodiments. The disclosure can be implemented in various combinations. The disclosure can have additional parts that can be added to the embodiments. The disclosure encompasses the omission of parts and / or elements from the embodiments. The disclosure encompasses the substitution or combination of parts and / or elements between one embodiment and another embodiment. The disclosed technical scope is not limited to the description of the embodiments. Some disclosed technical scopes are defined by the claims, and should be interpreted as including all modifications within the meaning and scope equivalent to the claims.

[0075] The disclosure in the specification, drawings, etc. is not limited by the claims. The disclosure in the specification, drawings, etc. encompasses the technical ideas described in the claims, and extends to more diverse and broader technical ideas than the technical ideas described in the claims. Therefore, various technical ideas can be extracted from the disclosure in the specification, drawings, etc. without being bound by the claims.

[0076] When an element or layer is referred to as being "on," "coupled," "connected," or "bonded," it may be directly on, coupled, connected, or bonded to another element or layer, and intervening elements or layers may be present. In contrast, when an element is referred to as being "directly on," "directly coupled," "directly connected," or "directly bonded" to another element or layer, no intervening elements or layers are present. Other terms used to describe relationships between elements should be construed in a similar manner (e.g., "between" vs. "directly between," "adjacent" vs. "directly adjacent," etc.). As used in this specification, the term "and / or" includes any and all combinations of one or more of the associated listed items. That is, reference to A and / or B means at least one of A and B.

[0077] Spatially relative terms such as "inside," "outside," "back," "below," "low," "top," "top," and the like are used herein to facilitate the description of one element or feature's relationship to other elements or features, as illustrated. Spatially relative terms may be intended to encompass different orientations of the device during use or operation in addition to the orientation depicted in the figures. For example, if the device in the figures were turned over, elements described as "below" or "directly below" other elements or features would then be oriented "above" the other elements or features. Thus, the term "bottom" can encompass both an orientation of top and bottom. The device may be otherwise oriented (rotated 90 degrees or at other orientations), and the spatially relative descriptors used in this specification would be interpreted accordingly.

[0078] (Disclosure of technical ideas) This specification discloses multiple technical ideas described in the following multiple clauses. Some clauses may be written in a multiple dependent form, with the subsequent clause referring to the preceding clause as an alternative. Furthermore, some clauses may be written in a multiple dependent form, referring to another multiple dependent clause. These multiple dependent clauses define multiple technical ideas.

[0079] <Technical philosophy 1> a printed circuit board (20) having one surface (21), a back surface (22) opposite to the one surface in the thickness direction, and through holes (23) opening in the one surface and the back surface; an electronic component (30) disposed on the one surface at a position not overlapping with the through hole in a plan view in the plate thickness direction; a cooler (50) disposed opposite to the one surface; a heat conduction member (60) interposed between the electronic component and the cooler and thermally connecting the electronic component and the cooler; a back plate (70) disposed on the rear surface and fixed to the cooler through the through hole; Equipped with the back plate has a main body portion (71) arranged to overlap at least a portion of the electronic component in the plan view and in contact with the back surface, and a plurality of leg portions (72) connected to the main body portion and spaced apart from the back surface, The electronic device has a fixing portion (90) for fixing the leg portion of the back plate to the cooler, the fixing portion (90) passing through the through hole and not in contact with the printed circuit board.

[0080] <Technical philosophy 2> The leg has a hole (73) through which a fixing screw (80) is inserted, The cooler has a cooler body (51) and a screw receiving portion (52) that protrudes from the cooler body toward the printed circuit board and has a screw hole into which the screw is screwed, The electronic device described in Technical Idea 1, wherein the fixing portion includes the screw and the screw receiving portion.

[0081] <Technical philosophy 3> The electronic device according to Technical Idea 2, wherein the screw receiving portion is inserted through the through hole and protrudes toward the back surface side.

[0082] <Technical philosophy 4> The screw receiving portion is not inserted into the through hole, The electronic device according to Technical Idea 2, wherein the screw passes through the through hole and protrudes toward the one surface side.

[0083] <Technical philosophy 5> The leg has a hole (73) through which a fixing screw (80) is inserted, The cooler has a screw hole (53) into which the screw is screwed, The electronic device described in Technical Idea 1, wherein the fixing portion includes the screw and the screw hole.

[0084] <Technical philosophy 6> The leg has a hole (73), The cooler has a cooler body (51) and a protrusion (55) that protrudes from the cooler body toward the printed circuit board and is engaged with the back plate while passing through the hole, The electronic device according to Technical Idea 1, wherein the fixing portion includes the protrusion.

[0085] <Technical philosophy 7> The electronic device according to any one of Technical Concepts 1 to 6, wherein the main body portion has a frame shape so as to overlap an outer peripheral region of the electronic component in the plan view.

[0086] <Technical philosophy 8> The electronic device according to Technical Idea 7, wherein a bypass capacitor (40) for the electronic component is mounted within an area surrounded by the frame-shaped main body on the rear surface.

[0087] <Technical philosophy 9> The electronic device according to any one of Technical Concepts 1 to 6, wherein the main body portion encompasses the entire solder placement area of the electronic component in the plan view.

[0088] <Technical Thought 10> The electronic device according to any one of Technical Ideas 1 to 9, wherein the electronic component is a BGA type electronic component equipped with a lid for heat dissipation.

[0089] <Technical Thought 11> The electronic device according to any one of Technical Ideas 1 to 10, wherein the electronic component includes a plurality of semiconductor chips. [Explanation of symbols]

[0090] 10...electronic device, 20...printed circuit board, 21...one side, 22...rear side, 23...through hole, 30...electronic component, 31, 31A, 31B...semiconductor chip, 32...rewiring board, 321...main board, 322...sub-board, 33...lid, 34, 341, 342...solder, 35...encapsulating resin body, 40...electronic component, 50...cooler, 51...cooler body, 511...flow path, 512...refrigerant, 52...screw receiving portion, 53...screw hole, 54...fin, 55...protrusion, 60, 61, 62...TIM, 70...back plate, 71...main body, 72...leg, 73...hole, 80...screw, 90...fixing portion

Claims

1. a printed circuit board (20) having one surface (21), a back surface (22) opposite to the one surface in the thickness direction, and through holes (23) opening in the one surface and the back surface; an electronic component (30) disposed on the one surface at a position not overlapping with the through hole in a plan view in the plate thickness direction; A cooler (50) disposed opposite to the one surface; a heat conduction member (60) interposed between the electronic component and the cooler and thermally connecting the electronic component and the cooler; a back plate (70) disposed on the rear surface and fixed to the cooler through the through hole; Equipped with The back plate has a main body portion (71) arranged so as to overlap at least a part of the electronic component in the plan view and in contact with the back surface, and a plurality of leg portions (72) connected to the main body portion and spaced apart from the back surface, The electronic device has a fixing portion (90) for fixing the leg portion of the back plate to the cooler, the fixing portion (90) passing through the through hole and not in contact with the printed circuit board.

2. The leg has a hole (73) through which a fixing screw (80) is inserted, The cooler has a cooler body (51) and a screw receiving portion (52) that protrudes from the cooler body toward the printed circuit board and has a screw hole into which the screw is screwed, The electronic device according to claim 1 , wherein the fixing portion includes the screw and the screw receiving portion.

3. The electronic device according to claim 2 , wherein the screw receiving portion is inserted through the through hole and protrudes toward the rear surface side.

4. The screw receiving portion is not inserted into the through hole, The electronic device according to claim 2 , wherein the screw passes through the through hole and protrudes toward the one surface side.

5. The leg has a hole (73) through which a fixing screw (80) is inserted, The cooler has a screw hole (53) into which the screw is screwed, The electronic device according to claim 1 , wherein the fixing portion includes the screw and the screw hole.

6. The legs have holes (73), The cooler has a cooler body (51) and a protrusion (55) that protrudes from the cooler body toward the printed circuit board and engages with the back plate while passing through the hole, The electronic device according to claim 1 , wherein the fixing portion includes the protrusion.

7. 7. The electronic device according to claim 1, wherein the main body is frame-shaped so as to overlap an outer peripheral region of the electronic component in the plan view.

8. 8. The electronic device according to claim 7, wherein a bypass capacitor (40) for the electronic components is mounted within an area surrounded by the frame-shaped main body on the rear surface.

9. 7. The electronic device according to claim 1, wherein the main body portion includes an entire solder placement area of the electronic component in the plan view.

10. 7. The electronic device according to claim 1, wherein the electronic component is a BGA type electronic component equipped with a lid for heat dissipation.

11. 7. The electronic device according to claim 1, wherein the electronic component includes a plurality of semiconductor chips.

Images