Electronic device

Abstract

An electronic device (100) comprises: a main board (20) having a semiconductor chip (26); heat dissipating fins (40) serving as a heat dissipating member; a die-cast frame (30); and a vapor chamber (50). The heat dissipating fins (40) have a heat-transfer surface portion (41) having a larger area than a chip area of the semiconductor chip (26), and dissipate heat transferred to the heat-transfer surface portion (41). The die-cast frame (30) has a frame bottom wall portion (31) positioned between the semiconductor chip (26) and the heat-transfer surface portion (41). The vapor chamber (50) is formed in the shape of a thin plate, is positioned between the frame bottom wall portion (31) and the heat-transfer surface portion (41), and effects surface diffusion of heat. The vapor chamber (50) is thermally connected to the frame bottom wall portion (31) by means of a frame-side heat conductor (60), and is thermally connected to the heat-transfer surface portion (41) by means of a fin-side heat conductor (70).

Description

Electronic device Cross-reference to related applications

[0001] This application is based on Japanese Patent Application No. 2024-161323 filed in Japan on September 18, 2024, the content of the base application is hereby incorporated by reference in its entirety.

[0002] The disclosure according to this specification relates to an electronic device.

[0003] The electronic device disclosed in Patent Document 1 includes a printed circuit board having circuit components and a shield cover having heat radiating fins. The circuit board is directly connected to the shield cover or connected to the shield cover via a heat conductor. Heat of the circuit components is radiated from the shield cover.

[0004] Japanese Patent Application Laid-Open No. 2002-314286

[0005] In recent years, the heat generation amount of semiconductor chips and the like provided as circuit components has been increasing. Therefore, it may be necessary to increase the size of the heat radiating member such as the heat radiating fin of Patent Document 1. However, even if the heat radiating member is enlarged, the heat of the semiconductor chip with a small area is only locally transmitted to the heat radiating member. As a result, it may be difficult to effectively perform cooling by the heat radiating member.

[0006] An object of the present disclosure is to provide an electronic device capable of effectively cooling a semiconductor chip using a heat radiating member.

[0007] To achieve the above object, one disclosed aspect is a circuit board having a semiconductor chip, a heat transfer surface portion having a larger area than the chip area of the semiconductor chip, a heat radiating member that dissipates heat transmitted to the heat transfer surface portion, a heat absorbing plate portion located between the semiconductor chip and the heat transfer surface portion, a frame member through which heat of the semiconductor chip is transmitted to the heat absorbing plate portion, a vapor chamber formed in a thin plate shape and located between the heat absorbing plate portion and the heat transfer surface portion for diffusing heat in a plane, a first heat conductor thermally connecting the heat absorbing plate portion and the vapor chamber, and a second heat conductor thermally connecting the vapor chamber and the heat transfer surface portion.

[0008] In this embodiment, the heat from the semiconductor chip transferred to the heat absorption plate is further transferred to the vapor chamber by the first heat conductor. The vapor chamber diffuses the heat transferred from the first heat conductor and then conducts it to the heat transfer surface via the second heat conductor. Therefore, even if the heat transfer surface of the heat dissipation member has a larger surface area than the chip area of ​​the semiconductor chip, the heat from the semiconductor chip can be conducted over a wide area of ​​the heat transfer surface. As a result, it becomes possible to effectively cool the semiconductor chip using the heat dissipation member.

[0009] Furthermore, the reference numbers in parentheses in the claims are merely examples of correspondences with specific configurations in the embodiments described later, and do not in any way limit the technical scope. In addition, combinations of claims not explicitly stated in the claims are also possible, provided that they do not cause any particular problems with the combination.

[0010] This is an exploded view showing the detailed configuration of an electronic device according to one embodiment of the present disclosure. This is a diagram showing the configuration of a heat dissipation module. This is a perspective view showing the process of assembling the heat dissipation module to a die-cast frame. This is a cross-sectional view showing the process of assembling the heat dissipation module to a die-cast frame. This is a diagram for explaining the details of the heat dissipation function.

[0011] The electronic device 100 shown in Figure 1, according to one embodiment of the present disclosure, is an Electronic Control Unit (ECU) for use in a vehicle. The electronic device 100 is, for example, an autonomous driving ECU that performs autonomous driving control or driver assistance control based on the recognition results of a plurality of autonomous sensors mounted on the vehicle. The electronic device 100 may be, for example, a display system ECU, a communication system ECU, a body system ECU, and an engine control system ECU. Furthermore, the electronic device 100 may be a zone ECU that integrates and manages multiple functions of a specific zone in the vehicle.

[0012] The electronic device 100 consists of a main unit 110, a sub-board 85, and a housing 90, etc., that houses them. The main unit 110 consists of a main board 20, a die-cast frame 30, heat dissipation fins 40, an electric fan 81, a fan duct 82, a vapor chamber 50, a frame-side heat conductor 60, and a fin-side heat conductor 70, etc.

[0013] Here, the vertical direction, width direction Hb, and depth direction OK in this disclosure are defined with respect to the main substrate 20. Specifically, the vertical direction (upward Ue and downward Si) is defined along the thickness direction of the main substrate 20 and is perpendicular to the main substrate 20. The width direction Hb and depth direction OK are defined along the surface direction of the main substrate 20. As an example, the width direction Hb is defined along the longitudinal direction of the main substrate 20. In contrast, the depth direction OK is defined along the short direction of the main substrate 20.

[0014] The main board 20 has the main processing circuits of the electronic device 100 formed on it. The main board 20 has a board body 21 and a plurality of semiconductor chips 26. The board body 21 is a multilayer printed wiring board made by laminating a composite insulating material that combines glass fiber and epoxy resin. The board body 21 is formed in the shape of a rectangular plate. The board body 21 is sandwiched between the die-cast frame 30 and the housing 90 (lower case 91). Of the two sides of the board body 21, one facing upwards Ue is the mounting surface 22, and the other facing downwards Si is the back surface 23. A number of electronic components, including at least one semiconductor chip 26, are mounted on the mounting surface 22. Electronic components include, for example, resistors, capacitors, inductors, diodes, transistors, and connectors. Some of the electronic components may be mounted on the back surface 23.

[0015] The semiconductor chip 26 is formed in a flat rectangular parallelepiped shape. Multiple semiconductor chips 26 are arranged on the same mounting surface 22. At least one of the multiple semiconductor chips 26 is an arithmetic processing unit such as a CPU (Central Processing Unit) and an MPU (Micro Processor Unit). The CPU or MPU has arithmetic functions for processing digital data and executes instructions based on a program. The semiconductor chip 26 may be a semiconductor element different from the CPU and MPU. For example, a GPU, FPGA, ASIC, SoC, chiplet integrator, DRAM, flash memory, communication IC, and power supply IC may be mounted on the mounting surface 22 as a semiconductor chip 26. Furthermore, the semiconductor chip 26 may be mounted on the mounting surface 22 as a semiconductor package such as a BGA (Ball Grid Array) or LGA (Land Grid Array), integrated with a package substrate.

[0016] The semiconductor chip 26 is thermally connected to the die-cast frame 30 by a chip-side thermal conductor 28 (see also Figures 3 to 6). The chip-side thermal conductor 28 is a thermal interface material (TIM) used to efficiently transfer heat. As an example, a heat dissipation sheet is used as the chip-side thermal conductor 28. The heat dissipation sheet is formed in a sheet or pad shape from a material such as silicone. The heat dissipation sheet has high thermal conductivity, flexibility, and electrical insulation properties. The chip-side thermal conductor 28 is positioned between the top surface of the semiconductor chip 26, which faces upward Ue, and the die-cast frame 30 (the bottom wall portion 31 of the frame, described later), in a state of being compressed in the vertical direction. Both sides of the chip-side thermal conductor 28 are in close contact with the semiconductor chip 26 and the die-cast frame 30, respectively. The chip-side thermal conductor 28 conducts the heat generated in the semiconductor chip 26, which is the heat source, to the die-cast frame 30.

[0017] The die-cast frame 30 (see also Figure 3) is a cast part made of a metal material (e.g., aluminum and copper) having high electrical and thermal conductivity. The die-cast frame 30 has a rectangular plate shape overall. The die-cast frame 30 is positioned above the main substrate 20 Ue. The die-cast frame 30 transfers the heat generated by each semiconductor chip 26, transmitted via each chip-side heat conductor 28, to the frame-side heat conductor 60. The die-cast frame 30 functions as a heat sink in cooperation with the heat dissipation fins 40. The die-cast frame 30 has a frame bottom wall portion 31, a frame peripheral wall portion 33, a support portion 36, and a fan mounting portion 39.

[0018] The frame bottom wall portion 31 is located between the plurality of semiconductor chips 26 and the heat dissipation fins 40 (heat transfer surface portion 41 described later). The frame bottom wall portion 31 is formed to cover the plurality of semiconductor chips 26 and is thermally connected to each of the plurality of semiconductor chips 26 via the chip-side heat conductor 28. The lower surface of the frame bottom wall portion 31 that faces each semiconductor chip 26 in the vertical direction may have irregularities formed thereon corresponding to the height and top surface shape of each semiconductor chip 26.

[0019] The frame peripheral wall portion 33 is erected from the frame bottom wall portion 31 upward towards Ue. The frame peripheral wall portion 33 is formed in a continuous rectangular ring shape that surrounds the vapor chamber 50. The frame peripheral wall portion 33 demarcates a filling area 34 that houses the vapor chamber 50 and the like above Ue above the frame bottom wall portion 31.

[0020] Multiple support portions 36 are provided on the outside of the frame peripheral wall portion 33 in the circumferential direction. The support portions 36 are configured to support the heat dissipation fins 40 from the frame bottom wall portion 31 side (lower side). The top surface of the support portion 36 facing upward Ue (hereinafter referred to as the support top surface 37) is formed to be substantially parallel to the frame bottom wall portion 31. The support top surface 37 is located slightly above Ue than the upper end surface of the frame peripheral wall portion 33. The support top surface 37 supports the heat dissipation fins 40 (mounting portion 44 described later) at multiple locations so that the lower surface of the heat dissipation fins 40 does not come into contact with the frame peripheral wall portion 33.

[0021] The fan mounting section 39 is provided in a position aligned with the frame bottom wall section 31 in the depth direction OK. An electric fan 81 is installed in the fan mounting section 39. A guide wall 39a is formed in the fan mounting section 39 to define the mounting position and orientation of the electric fan 81.

[0022] The heat dissipation fins 40 (see also Figures 3 and 6) are made of a metal material (e.g., aluminum and copper) having high electrical and thermal conductivity. The heat dissipation fins 40 are positioned above the die-cast frame 30 Ue. The heat dissipation fins 40 are arranged in the same position as the electric fan 81 in the depth direction OK. The heat dissipation fins 40 have a heat transfer surface portion 41, a fin body 43, and a mounting portion 44.

[0023] The heat transfer surface portion 41 is located in the central part of the base material of the heat dissipation fin 40, which is formed in a thin plate shape. The heat transfer surface portion 41 is the bottom surface of the heat dissipation fin 40 facing downward Si. The heat transfer surface portion 41 is formed to have a larger area than the chip area of ​​the semiconductor chip 26. The heat transfer surface portion 41 is located above Ue of the filling region 34. The heat transfer surface portion 41 transfers heat transmitted from the downward Si to the fin body 43.

[0024] The fin body 43 is a corrugated fin or pressed fin, etc., made by processing a thin metal sheet into a fin shape. The fin body 43 has a large number of fins arranged on it to increase the contact area with the air. The fin body 43 is provided above the heat transfer surface 41 Ue. The fin body 43 dissipates the heat transferred to the heat transfer surface 41 into the air.

[0025] The mounting portion 44 is provided on the edge of the base material of the heat dissipation fin 40. Multiple mounting holes are formed in the mounting portion 44. The mounting portion 44 is fixed at multiple points to each support portion 36 of the die-cast frame 30 by multiple fastening members 46 (screws, etc.) inserted through each mounting hole (see Figure 5). The mounting portion 44 is pressed against each support top surface 37 by the axial force of each fastening member 46. By fixing the mounting portion 44 to the support portion 36, the heat dissipation fin 40 is held in place by the die-cast frame 30.

[0026] The electric fan 81 consists of a motor, blades, housing, and power supply circuit, etc. The electric fan 81 is, for example, a centrifugal fan, and it draws in air along the rotation axis of the motor and discharges it outwards. The electric fan 81 is mounted on the fan mounting section 39 in a position where the rotation axis of the motor is aligned in the vertical direction. The electric fan 81 draws in air from above Ue and discharges it toward the fin body 43. Due to the forced convection by the electric fan 81, the heat dissipation fins 40 can efficiently release heat into the air.

[0027] The fan duct 82 is formed from a resin material or the like into a flat, bottomed container shape. The fan duct 82 is positioned above the die-cast frame 30 Ue so as to integrally cover the electric fan 81 and the heat dissipation fins 40. The fan duct 82 defines a flow path (hereinafter referred to as the cooling flow path) that controls the airflow generated by the electric fan 81. The fin body 43 is positioned within the cooling flow path.

[0028] The vapor chamber 50 is a heat dissipation device that utilizes boiling cooling. The vapor chamber 50 is formed in the shape of a thin plate. The thickness of the vapor chamber 50 is preferably 1 mm or less, for example, about 0.5 to 0.7 mm. The vapor chamber 50 has a higher thermal conductivity than the frame bottom wall portion 31 and the heat transfer surface portion 41, for example, a thermal conductivity of about 1000 W / mK. The vapor chamber 50 may have an even higher thermal conductivity.

[0029] The vapor chamber 50 consists of two outer shells and a working fluid confined in a sealed space partitioned by these outer shells. The outer shells are formed in the shape of thin plates from metal materials such as copper and aluminum. Fine protrusions are provided on the inner surfaces of the outer shells. A wick structure may be provided in the sealed space. The wick structure is a fine mesh structure that circulates the working fluid within the sealed space. The working fluid is, for example, water, alcohol, and fluorinated liquid. The working fluid has the characteristic of easily evaporating at low pressure and vaporizes due to the heat transmitted through the outer shells. The vaporized working fluid diffuses within the sealed space and returns to a liquid state by releasing heat to the low-temperature outer shell portion. The liquefied working fluid returns to the high-temperature outer shell portion and vaporizes again. Through this circulation process, the vapor chamber 50 continuously absorbs heat, diffuses the absorbed heat over a wide area, and then releases it.

[0030] The vapor chamber 50 is formed to have a larger area than the chip area of ​​the semiconductor chip 26 and has an area roughly the same as that of the heat transfer surface 41. The vapor chamber 50 is located between the frame bottom wall 31 and the heat transfer surface 41. The vapor chamber 50 diffuses heat across the surface in the width direction Hb and the depth direction Ok. Both sides of the vapor chamber 50 are sandwiched between the frame-side heat conductor 60 and the fin-side heat conductor 70, which are TIMs. The vapor chamber 50 is held to the heat transfer surface 41 via the fin-side heat conductor 70 (see Figure 2). The vapor chamber 50 is held by the heat dissipation fins 40 and housed in the packing region 34 while embedded in the frame-side heat conductor 60 (see Figure 6). A circumferential gap (hereinafter referred to as the packing gap 35) is formed between the vapor chamber 50 and the frame peripheral wall 33. The packing gap 35 is formed around the entire circumference of the vapor chamber 50. The filling gap 35 is ensured to be at least the thickness of the vapor chamber 50.

[0031] The frame-side heat conductor 60 thermally connects the frame bottom wall 31 and the vapor chamber 50. The frame-side heat conductor 60 conducts the heat transferred to the frame bottom wall 31 to the lower surface 52 of the vapor chamber 50 located above Ue. As an example, a heat dissipation gel 61 made of a non-metallic silicone gel or the like is used as the frame-side heat conductor 60. The heat dissipation gel 61 has insulating properties. The heat dissipation gel 61 may have fillers (thermal conductive fillers) added to enhance its thermal conductivity. The heat dissipation gel 61 is a fluid gel and is filled into the filling area 34 so that it reaches every corner of the filling area 34 (see Figure 6). The heat dissipation gel 61 is provided between the frame bottom wall 31 and the lower surface 52 of the vapor chamber 50 with a thickness of about 0.3 mm. The thickness of the heat dissipation gel 61 is thinner than that of the vapor chamber 50. The heat dissipation gel 61 is in close contact with the upper surface (bottom surface) of the frame bottom wall portion 31, the inner circumferential wall surface of the frame peripheral wall portion 33, and the lower surface 52 and each end surface 53 of the vapor chamber 50.

[0032] The fin-side heat conductor 70 thermally connects the vapor chamber 50 and the heat transfer surface 41. The fin-side heat conductor 70 conducts heat transferred to the upper surface 51 of the vapor chamber 50 to the heat transfer surface 41. The fin-side heat conductor 70 includes a phase-change material 71. The phase-change material 71 is a heat dissipation sheet that is flexible and electrically insulating. The phase-change material 71 is formed mainly from paraffin and fatty acids. The phase-change material 71 stores and releases thermal energy by utilizing phase change. The phase-change material 71 is provided between the upper surface 51 of the vapor chamber 50 and the heat transfer surface 41 with a thickness of about 0.3 mm. The thickness of the phase-change material 71 is thinner than that of the vapor chamber 50. The phase-change material 71 holds the vapor chamber 50 to the heat transfer surface 41. The phase-change material 71 softens with heat, thereby improving its adhesion to the upper surface 51 and the heat transfer surface 41, and reducing contact thermal resistance. In the following description, the assembly in which the vapor chamber 50 is held on the heat dissipation fins 40 by the fin-side heat conductor 70 will be referred to as the "heat dissipation module 140" (see Figure 2).

[0033] The sub-board 85 is mainly composed of a multilayer printed circuit board made by laminating a composite insulating material combining glass fiber and epoxy resin. The sub-board 85 has auxiliary electrical circuits that are electrically connected to the arithmetic processing circuits of the main board 20. The sub-board 85 is formed in a rectangular plate shape, similar to the main board 20. The sub-board 85 is positioned above the main unit 110 (Ue). The sub-board 85 is assembled to the die-cast frame 30 by fastening members such as screws.

[0034] The housing 90 is formed as a flat rectangular parallelepiped using metal and resin materials. The housing 90 is composed of a lower case 91 and an upper case 96, etc. The lower case 91 and the upper case 96 partition the housing space for the main unit 110 and the sub-board 85. The lower case 91 is formed as a container with a bottom. An air intake port 92 is opened on one of the four sides of the lower case 91. An exhaust port 93 is opened on another side adjacent to the side where the air intake port 92 is provided. When the electric fan 81 is operated, the air drawn into the housing space from the air intake port 92 cools the heat dissipation fins 40 and is discharged from the exhaust port 93. The upper case 96 is formed as a cover with a flange. The upper case 96 is attached to the lower case 91 from above Ue and closes the opening of the lower case 91.

[0035] <Explanation of the assembly method of the electronic device> Next, the assembly method (manufacturing method) of the electronic device 100 described above, specifically the assembly process of attaching the heat dissipation module 140 to the die-cast frame 30, will be explained in detail based on Figures 3 to 5, with reference to Figures 1 and 2.

[0036] In the assembly process, a heat dissipation gel 61, which serves as the frame-side heat conductor 60, is applied to the center of the filling area 34 (see Figure 3). The amount of heat dissipation gel 61 applied is pre-adjusted so that it does not protrude from the frame peripheral wall portion 33. After the application of the heat dissipation gel 61, the heat dissipation module 140 is positioned on the die-cast frame 30 such that the lower surface 52 of the vapor chamber 50 evenly compresses the heat dissipation gel 61 downwards toward Si. The heat dissipation gel 61 is spread outwards from the center of the filling area 34 toward the circumferential direction by being pressed by the vapor chamber 50 (see Figure 4).

[0037] The heat dissipation module 140 is fixed to the support portion 36 at multiple points by fastening members 46 (see Figure 5). The axial force of each fastening member 46 presses the mounting portion 44 against the support top surface 37. At this time, the upper end surface of the frame peripheral wall portion 33 does not come into contact with the lower surface of the heat dissipation fin 40. The heat dissipation gel 61 is further compressed by the vapor chamber 50 and protrudes into the filling gap 35 from between the lower surface 52 and the frame bottom wall portion 31. The filling gap 35 functions as a space to release the heat dissipation gel 61, so that the heat dissipation gel 61 adheres not only to the lower surface 52 but also to the end surface 53. The heat dissipation module 140 is assembled to the die-cast frame 30 with the vapor chamber 50 submerged in the heat dissipation gel 61.

[0038] <Explanation of Heat Dissipation Function> Next, the details of the heat dissipation function of the electronic device 100 will be further explained based on Figure 6.

[0039] The heat generated by the semiconductor chip 26, which acts as a heat source, is conducted to the frame bottom wall 31 by the chip-side heat conductor 28. The frame bottom wall 31 absorbs heat from the multiple semiconductor chips 26 via the chip-side heat conductor 28. The heat transferred from each semiconductor chip 26 to the frame bottom wall 31 is then conducted to the vapor chamber 50 by the frame-side heat conductor 60. The frame-side heat conductor 60 also conducts heat from the frame peripheral wall 33 to the vapor chamber 50.

[0040] The vapor chamber 50 diffuses the heat transferred to the lower surface 52 and the end surface 53. Due to the surface diffusion effect of the vapor chamber 50, the heat locally transferred to the lower surface 52 is transferred to almost the entire upper surface 51. As a result, the variation in surface temperature on the upper surface 51 is significantly smaller than on the lower surface 52. The heat diffused on the upper surface 51 is conducted to the entire heat transfer surface 41 by the fin-side heat conductor 70, and further conducted from the heat transfer surface 41 to the entire fin body 43.

[0041] As described above, even if heat is generated locally at each semiconductor chip 26, it becomes possible to raise the overall surface temperature of the fin body 43 in a generally uniform manner. As a result, heat dissipation is made by effectively utilizing the entire fin body 43, and the heat dissipation efficiency of the heat dissipation fin 40 is improved.

[0042] (Summary of Embodiment) In the present embodiment described so far, the heat of the semiconductor chip 26 transmitted to the frame bottom wall portion 31 is further transmitted to the vapor chamber 50 by the frame-side heat conductor 60. The vapor chamber 50 diffuses the heat transmitted from the frame-side heat conductor 60 in terms of area, and then conducts the heat to the heat transfer surface portion 41 from the fin-side heat conductor 70. Therefore, even if the heat transfer surface portion 41 of the radiation fin 40 has a larger area than the chip area of the semiconductor chip 26, the heat of the semiconductor chip 26 can be conducted to a wide range of the heat transfer surface portion 41. As a result, it becomes possible to effectively cool the semiconductor chip 26 using the radiation fin 40.

[0043] Also in the present embodiment, the radiation fin 40 is not directly joined to the die-cast frame 30, but is indirectly joined to the die-cast frame 30 through the vapor chamber 50 and the heat conductors 60 and 70 on both sides thereof. In a configuration using metal joining such as brazing and soldering, an increase in processing cost and deterioration of repairability may be caused. On the other hand, in a configuration that avoids such metal joining and sandwiches the vapor chamber 50 between the heat conductors 60 and 70, simplification of the structure is realized. As a result, it becomes possible to suppress the processing cost and ensure the repairability.

[0044] Further in the present embodiment, a configuration is adopted in which the vapor chamber 50 is sandwiched between the die-cast frame 30 and the radiation fin 40 instead of a copper plate or the like. When attempting to obtain a surface diffusion effect equivalent to that of the vapor chamber 50 with a copper plate or the like, the required plate thickness becomes significantly thicker than that of the vapor chamber 50 (for example, about 5 mm). Therefore, in a configuration adopting a copper plate, a structure for securely fixing the copper plate to the radiation fin 40 or the like with screws or the like is required, making it difficult to reduce the weight and thickness. On the other hand, in a configuration where the vapor chamber 50 is sandwiched instead of the copper plate, the vapor chamber 50 itself can be formed thinner, and the structure for mechanically joining can also be simplified. As a result, it becomes easy to reduce the weight and thickness.

[0045] In addition, in the present embodiment, the die-cast frame 30 has a frame peripheral wall portion 33 that surrounds the periphery of the vapor chamber 50. The frame peripheral wall portion 33 forms a circumferential filling gap 35 between it and the vapor chamber 50. Further, the frame-side heat conductor 60 has fluidity and is filled in the filling region 34 partitioned by the frame peripheral wall portion 33. According to such a configuration in which the fluid frame-side heat conductor 60 is spread, it becomes easy to control the dimension of the distance between the frame bottom wall portion 31 and the vapor chamber 50. Furthermore, since a circumferential filling gap 35 is secured between the vapor chamber 50 and the frame peripheral wall portion 33, the excess frame-side heat conductor 60 between the frame bottom wall portion 31 and the vapor chamber 50 can be discharged into the filling gap 35. As a result, the frame-side heat conductor 60 can be closely adhered to the lower surface 52 and the end surface 53 of the vapor chamber 50 without unevenness.

[0046] Also, the vapor chamber 50 of the present embodiment is housed in the filling region 34 in a state of being buried in the frame-side heat conductor 60. Therefore, a wide contact area between the vapor chamber 50 and the frame-side heat conductor 60 can be secured. As a result, heat transfer from the die-cast frame 30 to the vapor chamber 50 via the frame-side heat conductor 60 can be more effectively performed.

[0047] Furthermore, the die-cast frame 30 of the present embodiment further has a support portion 36 that supports the heat dissipation fins 40 from the side of the frame bottom wall portion 31. The support portion 36 is located outside the frame peripheral wall portion 33 in the circumferential direction. According to such a support structure, it becomes possible to appropriately control the distance between the lower surface 52 of the vapor chamber 50 and the upper surface of the frame bottom wall portion 31, in other words, the thickness of the frame-side heat conductor 60. As a result, even in a configuration employing the fluid frame-side heat conductor 60, it becomes difficult to cause deterioration of the thermal resistance due to an increase in the thickness of the frame-side heat conductor 60.

[0048] In addition, the heat dissipation fins 40 of this embodiment are fixed to the support portion 36 at multiple points by a plurality of fastening members 46. Therefore, the heat dissipation fins 40 are reliably brought into close contact with the support top surface 37 of the support portion 36 by the axial force of each fastening member 46. As a result, the thickness of the frame-side heat conductor 60 can be controlled more appropriately, and deterioration of thermal resistance caused by an increase in the thickness of the frame-side heat conductor 60 becomes less likely.

[0049] Furthermore, the fin-side heat conductor 70 of this embodiment includes a phase-change material 71 that holds the vapor chamber 50 to the heat transfer surface 41. The phase-change material 71 used in the fin-side heat conductor 70 has a very thin structure and can improve adhesion with the upper surface 51 and the heat transfer surface 41 by softening due to heat. As a result, the thermal resistance of the fin-side heat conductor 70 can be reduced. Moreover, the phase-change material 71 can maintain a predetermined hardness even when softened by heat. Therefore, the phase-change material 71 can hold the vapor chamber 50, eliminating the need for a configuration in which the vapor chamber 50 is mechanically joined to the heat dissipation fin 40.

[0050] Furthermore, in the main substrate 20 of this embodiment, multiple semiconductor chips 26 are arranged on the same mounting surface 22. The frame bottom wall 31 is thermally connected to each of the multiple semiconductor chips 26. As described above, with the miniaturization and increased functionality of electronic devices 100, the main substrate 20 tends to become denser. In addition, the miniaturization and increased performance of the semiconductor chips 26 mounted on the main substrate 20 increase the thermal density of each semiconductor chip 26, resulting in a dense concentration of heat sources on the mounting surface 22. However, by thermally connecting each semiconductor chip 26 to the frame bottom wall 31 and diffusing the heat of each semiconductor chip 26 across the surface using the vapor chamber 50, it becomes possible to efficiently dissipate the densely generated heat while avoiding structural complexity.

[0051] In the above embodiment, the main board 20 corresponds to the "circuit board," the die-cast frame 30 corresponds to the "frame member," the frame bottom wall portion 31 corresponds to the "heat absorption plate portion," the frame peripheral wall portion 33 corresponds to the "frame wall," and the filling gap 35 corresponds to the "circumferential gap." Furthermore, the heat dissipation fin 40 corresponds to the "heat dissipation member," the frame-side heat conductor 60 corresponds to the "first heat conductor," and the fin-side heat conductor 70 corresponds to the "second heat conductor."

[0052] (Other Embodiments) Although one embodiment of the present disclosure has been described above, the present disclosure is not to be construed as being limited to the above embodiment, and can be applied to various embodiments and combinations without departing from the gist of the present disclosure.

[0053] In the above embodiment, the specific configurations of the TIM used as the chip-side heat conductor 28, the frame-side heat conductor 60, and the fin-side heat conductor 70 may be modified as appropriate. For example, a heat dissipation gel may be used for the chip-side heat conductor 28. A heat dissipation sheet or heat dissipation grease may be used for the frame-side heat conductor 60. Furthermore, a heat dissipation sheet may be used for the fin-side heat conductor 70.

[0054] In the above embodiment, the frame peripheral wall portion 33 was configured to block the heat dissipation gel 61, causing it to flow around the vapor chamber 50. However, this frame peripheral wall portion 33 may be omitted. That is, the excess heat dissipation gel 61 may simply protrude outwards from between the frame bottom wall portion 31 and the vapor chamber 50. Furthermore, the amount of heat dissipation gel 61 applied may be limited to such an extent that it does not protrude from between the frame bottom wall portion 31 and the vapor chamber 50.

[0055] In the above embodiment, a support portion 36 was provided on the outside of the frame peripheral wall portion 33. Such a support portion 36 may be integrally formed with the frame peripheral wall portion 33. In addition, the method of fixing the heat dissipation fin 40 to the die-cast frame 30 is not limited to screw fixing by fastening member 46. The heat dissipation fin 40 may be fixed to the die-cast frame 30 by rivets or clips, or by crimping or the like.

[0056] The semiconductor chip 26 provided on the main substrate 20 may be just one. Even with a single semiconductor chip 26 configuration, the surface diffusion effect of the vapor chamber 50 can improve the heat dissipation efficiency of the heat dissipation fins 40.

[0057] The heat dissipation member that dissipates the heat transferred from the vapor chamber 50 is not limited to the heat dissipation fins 40 of the above embodiment. For example, a heat pipe that moves the heat from the heat transfer surface 41 to another location, another vapor chamber, or a heat exchanger of a liquid cooling system may be provided as a heat dissipation member. Furthermore, the electric fan 81 that supplies forced convection to the heat dissipation fins 40 may be omitted.

[0058] In this disclosure, the phrase "thermally connected" means physical contact or connection between two or more elements for the efficient transfer of thermal energy. This connection allows heat from one element to be transferred to the other. That is, one element may be directly connected to the other, or indirectly connected via an intervening element, provided that efficient heat transfer is possible.

[0059] The vehicles equipped with the electronic devices described in this disclosure are not limited to Personally Owned Vehicles (POVs) that are generally assumed to be privately owned. The electronic devices may be installed in rental cars, manned taxis, ride-sharing vehicles, freight vehicles, and buses, etc. Furthermore, the electronic devices may be installed in driverless vehicles used in mobility services, construction machinery, agricultural machinery, railway vehicles, trams, and Dual Mode Vehicles (DMVs), etc. In addition, the electronic devices may be installed in ships and electric aircraft such as drones and eVTOLs. Moreover, the electronic devices may be mobile terminals, personal computers, and household electrical appliances, etc. Furthermore, the electronic devices may be stationary server equipment and network equipment installed in data centers and server rooms, etc.

[0060] (Disclosure of Technical Ideas) This specification discloses several technical ideas as described in the following paragraphs. Some paragraphs may be written in a multiple dependent form, where subsequent paragraphs optionally refer to preceding paragraphs. Furthermore, some paragraphs may be written in a multiple dependent form, where they refer to other multiple dependent forms. These paragraphs written in multiple dependent forms define several technical ideas.

[0061] (Technical Concept 1) An electronic device comprising: a circuit board (20) having a semiconductor chip (26); a heat dissipation member (40) having a heat transfer surface portion (41) with a larger surface area than the chip area of ​​the semiconductor chip, and dissipating heat transferred to the heat transfer surface portion; a frame member (30) having a heat absorption plate portion (31) located between the semiconductor chip and the heat transfer surface portion, to which heat from the semiconductor chip is transferred; a vapor chamber (50) formed in the shape of a thin plate, located between the heat absorption plate portion and the heat transfer surface portion, and diffusing heat across the surface; a first heat conductor (60) thermally connecting the heat absorption plate portion and the vapor chamber; and a second heat conductor (70) thermally connecting the vapor chamber and the heat transfer surface portion. (Technical Idea 2) The electronic device according to Technical Idea 1, wherein the frame member further comprises a frame wall (33) that surrounds the vapor chamber and forms a circumferential gap (35) between itself and the vapor chamber, and the first heat conductor is fluid and fills a filling region (34) partitioned by the frame wall. (Technical Idea 3) The electronic device according to Technical Idea 2, wherein the vapor chamber is housed in the filling region embedded in the first heat conductor. (Technical Idea 4) The electronic device according to Technical Idea 2 or 3, wherein the frame member further comprises a support portion (36) located outside the frame wall in the circumferential direction and supporting the heat dissipation member from the heat absorption plate side. (Technical Idea 5) The electronic device according to Technical Idea 4, wherein the heat dissipation member is fixed to the support portion at multiple locations by a plurality of fastening members (46). (Technical Idea 6) The electronic device according to any one of Technical Ideas 1 to 5, wherein the second heat conductor comprises a phase change material (71) that holds the vapor chamber to the heat transfer surface. (Technical Concept 7) The circuit board has a plurality of semiconductor chips arranged on the same mounting surface (22), and the heat absorption plate portion is thermally connected to each of the plurality of semiconductor chips, as described in any one of Technical Concepts 1 to 6.

Claims

1. An electronic device comprising: a circuit board (20) having a semiconductor chip (26); a heat dissipation member (40) having a heat transfer surface portion (41) with a larger surface area than the chip area of ​​the semiconductor chip, which dissipates heat transferred to the heat transfer surface portion; a frame member (30) having a heat absorption plate portion (31) located between the semiconductor chip and the heat transfer surface portion, to which heat from the semiconductor chip is transferred; a vapor chamber (50) formed in the shape of a thin plate, located between the heat absorption plate portion and the heat transfer surface portion, which diffuses heat across the surface; a first heat conductor (60) which thermally connects the heat absorption plate portion and the vapor chamber; and a second heat conductor (70) which thermally connects the vapor chamber and the heat transfer surface portion.

2. The electronic device according to claim 1, wherein the frame member further comprises a frame wall (33) that surrounds the vapor chamber and forms a circumferential gap (35) between itself and the vapor chamber, and the first heat conductor is fluid and fills a filling region (34) partitioned by the frame wall.

3. The electronic device according to claim 2, wherein the vapor chamber is housed in the packed region while embedded in the first heat conductor.

4. The electronic device according to claim 2 or 3, wherein the frame member further comprises a support portion (36) located outside the frame wall in the circumferential direction, which supports the heat dissipation member from the heat absorption plate portion side.

5. The electronic device according to claim 4, wherein the heat dissipation member is fixed to the support portion at multiple locations by a plurality of fastening members (46).

6. The electronic device according to claim 1, wherein the second heat conductor includes a phase-change material (71) that holds the vapor chamber to the heat transfer surface.

7. The electronic device according to claim 1, wherein the circuit board has a plurality of semiconductor chips arranged on the same mounting surface (22), and the heat absorption plate portion is thermally connected to each of the plurality of semiconductor chips.

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