Electronic apparatus

Abstract

To provide an electronic apparatus capable of more efficiently dissipating heat generated from electronic components.SOLUTION: An electronic apparatus 1 includes an electronic component 3, a printed wiring board 5, and a heat dissipation member 7. A band-shaped pressing portion 9 is formed in the printed wiring board 5 by a first slit-shaped notch 13a and a second slit-shaped notch 13b. The pressing portion 9 includes two fixing portions 9a and a pressing portion 9b. By an elastic force generated by bending the pressing portion 9b in contact with a second main surface 17b of the electronic component 3, one fixing portion 9a and the other fixing portion 9a are fixed to the heat dissipation member 7 by rivets 23 in a state where the first main surface 17a of the electronic component 3 is pressed against the heat dissipation member 7.SELECTED DRAWING: Figure 1

Description

[Technical Field]

[0001] The present disclosure relates to electronic devices. [Background technology]

[0002] Electronic circuits use many electronic components that generate heat during operation. If the temperature of the electronic components exceeds a certain level, it can cause problems in the operation of the electronic circuit and may also shorten the lifespan of the electronic components.

[0003] To avoid such problems, some electronic components are combined with a heat dissipation member to prevent the temperature of the electronic component from rising above a certain temperature. Various methods have been devised to closely attach the electronic component to the heat dissipation member in order to efficiently dissipate the heat generated in the electronic component.

[0004] For example, Patent Document 1 proposes a power semiconductor device that uses a curved heat dissipation member, sandwiches a power semiconductor element between the curved heat dissipation member and a fixing member, and fixes it with bolts and nuts. [Prior art documents] [Patent documents]

[0005] [Patent Document 1] Patent Publication No. 2021-72363 Summary of the Invention [Problem to be solved by the invention]

[0006] Electronic circuits are required to dissipate heat generated from electronic components more efficiently and easily.

[0007] The present disclosure has been made based on such developments, and its purpose is to provide an electronic device that can more efficiently dissipate heat generated from electronic components. [Means for solving the problem]

[0008] The electronic device according to the present disclosure includes a printed wiring board, one or more electronic components, and a heat dissipation member. The one or more electronic components are mounted on the printed wiring board and have first and second main surfaces facing each other. The heat dissipation member is in thermal contact with the first main surface of the electronic component. The printed wiring board includes a thickness direction deformation portion that allows deformation in the thickness direction of the printed wiring board. The first main surface of the electronic component is in thermal contact with the heat dissipation member via the thickness direction deformation portion. [Effects of the Invention]

[0009] In the electronic device according to the present disclosure, a printed wiring board on which one or more electronic components are mounted includes a thickness-direction deformation portion that allows deformation of the printed wiring board in the thickness direction, whereby a first main surface of the electronic component is in thermal contact with a heat dissipation member. [Brief explanation of the drawings]

[0010] [Figure 1] 1 is an exploded perspective view of an electronic device according to a first embodiment. [Figure 2] FIG. 2 is a perspective view of the electronic device in the embodiment. [Figure 3] FIG. 2 is a side view of the electronic device in the embodiment. [Figure 4] FIG. 2 is a top view of the electronic device in the embodiment. [Figure 5] FIG. 10 is a perspective view showing a structure of a printed wiring board in an electronic device according to a modified example of the embodiment. [Figure 6] FIG. 10 is an exploded perspective view of an electronic device according to a second embodiment. [Figure 7] FIG. 2 is a side view of the electronic device in the embodiment. [Figure 8] FIG. 10 is a perspective view showing the structure of a printed wiring board in an electronic device according to a first modified example of the embodiment. [Figure 9]FIG. 10 is a perspective view showing the structure of a printed wiring board in an electronic device according to a second modified example of the embodiment. [Figure 10] FIG. 11 is a perspective view showing the structure of a printed wiring board in an electronic device according to a third modified example of the embodiment. [Figure 11] FIG. 11 is a perspective view showing the structure of a printed wiring board in an electronic device according to a third modified example of the embodiment. [Figure 12] FIG. 11 is a perspective view showing the structure of a printed wiring board in an electronic device according to a fourth modified example of the embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0011] (Introduction) It is known that when electronic components use electrical energy to perform a desired function, the temperature of the electronic components rises due to heat generated by the conversion of a portion of the electrical energy. In particular, power conversion devices that consume high power and integrated circuits with high circuit integration and high operating frequencies generate a large amount of heat. Therefore, as the temperature rises, the performance of the power conversion devices and the like may deteriorate, or their lifespan may be shortened.

[0012] In order to avoid such problems, it is important to suppress the temperature rise of electronic components by actively releasing the heat generated in power conversion devices, etc. to the outside or by cooling the power conversion devices, etc.

[0013] In order to efficiently dissipate heat generated in electronic components, a heat dissipation member such as a heat sink is generally used. One example of a heat sink is a heat sink with multiple fins. The multiple fins are arranged parallel to each other and spaced apart.

[0014] This type of heat sink is formed by extruding a material that has good thermal conductivity and is easy to process, such as aluminum. By providing multiple fins, the surface area of ​​the heat sink can be increased, allowing heat generated by electronic components to be efficiently dissipated into the air.

[0015] In order to dissipate heat generated in an electronic component from a heat dissipation member such as a heat sink, it is necessary to efficiently conduct the heat generated in the electronic component to the heat dissipation member. To achieve this, it is desirable to increase the contact area between the electronic component and the heat dissipation member.

[0016] If the contact surface (heat dissipation surface) of the electronic component that comes into contact with the heat dissipation member and the contact surface of the heat dissipation member that comes into contact with the electronic component were both ideally flat, it would be possible to achieve perfect adhesion between the two. However, the contact surfaces of the electronic component and the heat dissipation member that come into contact with each other may have small irregularities during processing. Furthermore, warping may occur due to the characteristics of the materials of the electronic component or the heat dissipation member.

[0017] This makes it difficult to bring the contact surfaces of the electronic component and the heat dissipation member into close contact, resulting in gaps between the contact surfaces of the electronic component and the heat dissipation member.If there are many gaps and the contact area between the contact surfaces of the electronic component and the heat dissipation member is small, heat conduction from the electronic component to the heat dissipation member will not be efficient.

[0018] Therefore, a method is adopted in which a material (layer) with relatively high thermal conductivity, such as a thermally conductive sheet, a thermally conductive pad, or silicone grease, is sandwiched between the contact surfaces of the electronic component and the heat dissipation member to fill the gap, which allows for efficient heat conduction from the electronic component to the heat dissipation member.

[0019] Such highly thermally conductive materials are called thermal interface materials (hereinafter referred to as "TIM"). A material softer than the electronic component and the heat dissipation member is used as the TIM to absorb the unevenness of the surfaces of the electronic component and the heat dissipation member. For this reason, in order to absorb the unevenness of each surface and fill the gap, the electronic component and the heat dissipation member are joined by bonding the TIM itself. Alternatively, the TIM is sandwiched between the electronic component and the heat dissipation member and held in place under pressure.

[0020] Common methods for holding an electronic component and a heat dissipation member under pressure include using a spring to apply a constant pressure to hold the electronic component and heat dissipation member together with a TIM sandwiched between them, or using screws tightened with a constant torque to hold the electronic component and heat dissipation member together with a TIM sandwiched between them.

[0021] In particular, in the method of fastening an electronic component to a heat dissipation member with screws, the pressure acting on the electronic component varies greatly depending on the tightening torque, so it is necessary to manage the tightening torque. Managing the tightening torque is cumbersome. In addition, there is a concern that pressure may be concentrated around the screw when the screw is tightened.

[0022] When screws are tightened with a strong torque, pressure acts locally on the electronic components, heat dissipation material, and TIM, which can cause warping (deformation).As a result, the electronic components, TIM, and heat dissipation material are in close contact with each other around the screws, but in areas away from the screws, the pressure caused by tightening the screws is weak, raising concerns that the heat dissipation effect may be reduced.

[0023] Patent Document 1 proposes a heat dissipation member (heat sink) with a cross-sectional shape that is convex toward the electronic component in order to prevent pressure from concentrating around the screw. By using such a heat dissipation member, the center of the electronic component, which is far from the screw, is tightly attached to the heat dissipation member with strong pressure.

[0024] If the electronic component is relatively hard and does not easily deform when pressure is applied, tightening the screws will deform the heat dissipation member so that its ends approach the electronic component while its center abuts the electronic component, thereby flattening the contact surface of the heat dissipation member that comes into contact with the electronic component and increasing the contact area between the heat dissipation member and the electronic component.

[0025] Generally, electronic components have a structure in which electronic circuit elements are encapsulated in resin (molded), and electronic components are more susceptible to deformation when pressure is applied than heat dissipation members. Therefore, if the heat dissipation member deforms when its center is in contact with the electronic component, the pressure acting on the electronic component may deform the encapsulated electronic circuit elements, the wire bonding or solder joints that electrically connect the electronic circuit elements, etc. As a result, the electronic circuit elements may be destroyed, the electrical connections may be impaired, or the reliability of the electronic component may be reduced.

[0026] The electronic device according to the present disclosure has been made to solve these technical problems. Hereinafter, the electronic device according to the present disclosure will be specifically described in each embodiment.

[0027] Embodiment 1 An example of an electronic device according to embodiment 1 will be described. As shown in Fig. 1, Fig. 2, and Fig. 3, electronic device 1 includes electronic component 3, printed wiring board 5, and heat dissipation member 7. Printed wiring board 5 is formed with pressing portion 9 as a thickness direction deformation portion. Electronic component 3 is in thermal contact with heat dissipation member 7 by means of the pressing portion.

[0028] 4, electronic component 3 includes sealing body 17 that seals an electronic circuit element (not shown). Sealing body 17 has first and second main surfaces 17a and 17b that face each other. Sealing body 17 also has first and second side portions 17c and 17d that face each other and are spaced apart from each other.

[0029] Leads 19 protrude from each of first side portion 17c and second side portion 17d of electronic component 3 (sealant 17). First lead terminal 19a protrudes from first side portion 17c. Second lead terminal 19b protrudes from second side portion 17d. First lead terminal 19a and second lead terminal 19b are bonded to printed wiring board 5.

[0030] The electronic device 1 will be described in more detail. As shown in Figures 1 and 2, the pressing portion 9 is formed on the printed wiring board 5. The pressing portion 9 is defined in a band shape by a first slit-shaped notch 13a and a second slit-shaped notch 13b formed on the printed wiring board 5 so as to extend in one direction with a gap between them. The pressing portion 9 has two fixing portions 9a serving as a first fixing portion and a second fixing portion, and a pressing portion 9b.

[0031] One fixing portion 9a is formed on one side of the band-like extending pressing portion 9. The other fixing portion 9a is formed on the other side of the band-like extending pressing portion 9. The pressing portion 9b is located between the one fixing portion 9a and the other fixing portion 9a. The one fixing portion 9a and the other fixing portion 9a are fixed to the heat dissipation member 7 by rivets 23 in a state in which the first main surface 17a of the electronic component 3 is pressed against the heat dissipation member 7 by an elastic force generated by bending the pressing portion 9b that is in contact with the second main surface 17b of the electronic component 3.

[0032] Furthermore, a folded structure is formed on the printed wiring board 5 to relieve stress that occurs in the printed wiring board 5 as the pressing portion 9b bends. The folded structure includes folded connection portions 11 that serve as stress relief portions and connect the area where the pressing portion 9 is formed to its surrounding area. Four folded connection portions 11 are formed. The area where the pressing portion 9 is formed is connected to the surrounding area located around the area where the pressing portion 9 is formed by the four folded connection portions 11.

[0033] The folded structure is formed by a third notch 13c and a fourth notch 13d, each of which is slit-shaped. The third notch 13c is formed in a manner that surrounds one of the fixed portions 9a except in the direction in which the pressing portion 9b is located. The fourth notch 13d is formed in a manner that surrounds the other of the fixed portions 9a except in the direction in which the pressing portion 9b is located.

[0034] On one side of fixed portion 9a, one folded connection portion 11 is formed in a portion of printed wiring board 5 sandwiched between first notch 13a and third notch 13c. One folded connection portion 11 is formed in a portion of printed wiring board 5 sandwiched between second notch 13b and third notch 13c.

[0035] On the other fixed portion 9a side, one folded connection portion 11 is formed in a portion of the printed wiring board 5 sandwiched between the first notch 13a and the fourth notch 13d. Another folded connection portion 11 is formed in a portion of the printed wiring board 5 sandwiched between the second notch 13b and the fourth notch 13d.

[0036] In the peripheral region of printed wiring board 5, there may be mounted components, such as chip ceramic capacitors, that may be damaged by large distortion of printed wiring board 5. Since printed wiring board 5 has folded connection portion 11 (folded structure), tilting of the surface of the peripheral region is suppressed even if pressing portion 9 is displaced (bent) in the thickness direction.

[0037] This makes it possible to suppress distortion in the peripheral region. That is, when the pressing portion 9 is displaced in the thickness direction, the stress generated in the printed wiring board 5 is alleviated by the folded connection portion 11.

[0038] The above-mentioned first notch 13a, second notch 13b, third notch 13c and fourth notch 13d can be formed in the printed wiring board 5 without any additional process when processing the exterior shape of the printed wiring board 5, for example, by punching using a die press or cutting using a router bit.

[0039] A material that has both electrical insulation and mechanical strength is used for the printed wiring board 5. Generally, the printed wiring board 5 has a structure in which a glass fiber reinforced plastic (GFRP) is used as a base material and multiple sheets of this base material are stacked on top of each other. The glass fiber reinforced plastic is made by impregnating glass cloth with epoxy resin.

[0040] There is a region that elastically deforms in response to bending displacement in the thickness direction of the printed wiring board 5. The elastic force generated during elastic deformation varies depending on the thickness and width of the printed wiring board 5. Therefore, the required elastic force can be obtained by processing the printed wiring board 5 to the appropriate dimensions. The pressing portion 9 presses (biases) the electronic component 3 toward the heat dissipation member 7 with an appropriate pressing pressure (elastic force).

[0041] The pressing portion 9 is fixed to the heat dissipation member 7 by two fixing portions 9a. The heat dissipation member 7 has a step 15. The height of the step 15 is smaller than the height (thickness) of the electronic component 3. Therefore, when the pressing portion 9 is fixed to the heat dissipation member 7, the pressing portion 9 (pressing portion 9b) bends in accordance with the difference between the height of the electronic component 3 and the height of the step 15. The bending of the pressing portion 9 (pressing portion 9b) generates an elastic force in the pressing portion 9. This elastic force presses the electronic component 3 against the heat dissipation member 7.

[0042] As for this difference, in addition to providing a step 15 in the heat dissipation member 7, for example, a cylindrical spacer member may be interposed between the heat dissipation member without a step and the pressing portion 9. Alternatively, a step and a spacer member may be combined. By adjusting the height of the spacer member, etc., the difference can be easily adjusted, and the elastic force generated by bending the pressing portion 9 (pressing portion 9b) can be adjusted to any elastic force.

[0043] The pressing force that presses the electronic component 3 against the heat dissipation member is an elastic force that is generated by bending the pressing portion 9. As a result, even when the pressing portion 9 is fixed to the heat dissipation member 7 using a screw, the pressing force due to the tightening torque of the screw does not affect the electronic component 3 or the heat dissipation member 7. For this reason, as shown in FIG. 1, the pressing portion 9 can be fixed to the heat dissipation member 7 using a simple member such as a rivet 23.

[0044] Furthermore, by forming a part of the printed wiring board 5 as the retaining portion 9, it is possible to mount another circuit element such as a temperature sensor 21 on the retaining portion 9. As described above, an increase in the temperature of the electronic component 3 may degrade the performance of the electronic component 3. It may also shorten the lifespan of the electronic component 3. For this reason, the temperature increase of the electronic component 3 may be monitored. By monitoring the temperature increase of the electronic component 3, it is possible to suppress the output of the electronic component 3, for example. It is also possible to issue an alarm to notify that the temperature of the electronic component 3 has abnormally increased.

[0045] Conventionally, for example, a temperature sensor has been built into the electronic component itself. Alternatively, a temperature sensor has been placed near the lead terminal of the electronic component where it is soldered to the printed circuit board to indirectly measure the temperature of the electronic component. Furthermore, a temperature sensor has been attached to the electronic component or heat dissipation member as a separate structural component with a temperature sensor and lead wires.

[0046] In the electronic device 1 described above, the elastic force generated in the pressing portion 9b abutting against the electronic component 3 causes the electronic component 3 to adhere tightly to the heat dissipation member 7. Therefore, by mounting the temperature sensor 21 on the pressing portion 9, it is possible to efficiently measure the temperature rise of the heat-generating portion of the electronic component 3. Furthermore, the temperature sensor 21 can be mounted by soldering in the same process in which other components are mounted on the printed wiring board 5. Furthermore, the copper foil circuit pattern formed on the printed wiring board 5 can electrically connect the temperature sensor 21 to other electronic components mounted on other portions of the printed wiring board 5, allowing the temperature of the electronic component 3 to be measured simply and efficiently.

[0047] As described above, the pressing portion 9 and its surrounding area are connected by the folded connection portion 11. The folded connection portion 11 is not limited to being formed in a manner that allows elastic deformation, but may also be formed in a manner that allows plastic deformation. For example, by narrowing the width of the folded connection portion 11, it becomes easier to cause large plastic deformation. This allows for a larger displacement in the thickness direction that occurs between the pressing portion 9 and the printed wiring board 5, and can be applied to thicker electronic components 3.

[0048] Further, the case where four folded connection portions 11 are formed as connection portions connecting the pressing portion 9 and its surrounding area has been described. The number of connection portions is not limited to four (four locations). As shown in FIG. 5, there may be only one connection portion 12 connecting the pressing portion 9 and its surrounding area. The pressing portion 9 is formed in a band shape by the fifth notch 13e. One end of the pressing portion 9 is connected to the printed wiring board 5, and the other end of the pressing portion is separated from the printed wiring board 5.

[0049] In this case, in order to stably arrange the printed wiring board 5 and the heat dissipation member 7 (see FIG. 1), for example, the printed wiring board 5 and the heat dissipation member 7 need to be fixed to a housing (not shown) that houses them. Furthermore, by providing two or more connection points, the printed wiring board 5 and the heat dissipation member 7 can be arranged parallel to each other and stably.

[0050] Embodiment 2 An example of an electronic device according to a second embodiment will be described. Here, a case will be described in which two types of electronic components with different heights are mounted as electronic components. When multiple electronic components are mounted, electronic components with different design dimensions may be mounted. Furthermore, even for electronic components with the same design dimensions, the height from the surface of the printed wiring board to the heat-generating surface of the electronic component may differ slightly due to manufacturing tolerances of the electronic components or mounting tolerances when mounted on the printed wiring board.

[0051] When electronic components of different heights are attached to a flat portion of a heat dissipation member, even if the first main surface (heat-generating surface) of each electronic component is flat, a gap will be created between the relatively low-height electronic component and the heat dissipation member, making it impossible to bring them into close contact. If a gap is created between the two, heat generated in the electronic component cannot be effectively transferred to the heat dissipation member, and a rise in the temperature of the electronic component will be unavoidable.

[0052] The electronic device according to the second embodiment has a structure that allows the first main surfaces of electronic components of different heights to be closely attached to a heat dissipation member. As shown in Figures 6 and 7, the electronic device 1 includes a first electronic component 3a and a second electronic component 3b as electronic components 3, a printed wiring board 5, and a heat dissipation member 7.

[0053] The height of the first electronic component 3a from the surface of the printed wiring board 5 to the first main surface 17a of the first electronic component 3a is height H1. The height of the second electronic component 3b from the surface of the printed wiring board 5 to the first main surface 17a of the second electronic component 3b is height H2. Height H1 is shorter than height H2.

[0054] The printed wiring board 5 includes a first mounting portion 31 on which the first electronic component 3a is mounted and a second mounting portion 33 on which the second electronic component 3b is mounted. The first mounting portion 31 is defined by a sixth notch 41a. The first mounting portion 31 and the second mounting portion 33 are connected by a connecting portion 35 which serves as a thickness direction deformation portion.

[0055] In the electronic device 1, the first mounting portion 31, on which the first electronic component 3a having a height H1 is mounted, is positioned closer to the heat dissipation member 7 than the second mounting portion 33 by the connecting portion 35, so that the first main surface 17a of the first electronic component 3a is in thermal contact with the heat dissipation member 7. When the first electronic component 3a and the second electronic component 3b are separated by a sufficient distance, it is relatively easy to increase the displacement in the thickness direction. However, when the distance between them is short, it becomes difficult to increase the displacement in the thickness direction.

[0056] The electronic device 1 described above employs a structure in which the width of the connecting portion 35 is narrowed and a V-shaped groove 37a is formed on the surface of the connecting portion 35, making it easier to bend the connecting portion 35 in the thickness direction. The width of the connecting portion 35 is narrowed by forming a sixth notch 41a in the printed wiring board 5. The V-shaped groove 37a is formed in a direction intersecting (substantially perpendicular to) the direction connecting the first mounting portion 31 and the second mounting portion 33. By bending the connecting portion 35 in the thickness direction, the first main surface 17a of each of the first electronic component 3a and the second electronic component 3b, which are different in height, can be brought into thermal contact with the heat dissipation member 7.

[0057] A typical method for dividing a continuously processed printed wiring board into multiple printed wiring boards is to machine V-grooves on both sides of the printed wiring board. For example, if a discarded board area for board transportation is provided around the periphery of the printed wiring board during the manufacturing process, the discarded board area that becomes unnecessary after processing is divided at the V-groove. In this case, the V-groove area is broken by applying a large bending force, and the discarded board area is divided.

[0058] In the electronic device 1 described above, the V-groove 37a is formed only on one surface of the printed wiring board 5. The V-groove 37a is formed in the connecting portion 35 so that the connecting portion 35 has a thickness that will not break within a range of displacement in the thickness direction. A copper foil pattern can be disposed on the other surface of the printed wiring board 5 where the V-groove 37a is not formed, enabling electrical connection between the first mounting portion 31 and the second mounting portion 33.

[0059] In this way, by making a part of the connecting portion 35 have a structure that makes it easy to bend, it is possible to easily displace the connecting portion 35 in the thickness direction. The structure that makes the connecting portion 35 easy to bend is not limited to the structure in which the V-shaped groove 37a is formed in the connecting portion 35.

[0060] 8, the connecting portion 35 may have perforated openings 37b. The openings 37b may be formed as through-holes using a drill or the like. By forming the openings 37b, the effective widths of the portions connected to the first mounting portion 31 and the second mounting portion 33 are shortened, making it easier to displace the connecting portion 35 in the thickness direction.

[0061] 9, a structure in which a thin-walled portion 37c is formed in the connecting portion 35 may also be used. The thin-walled portion 37c can be formed, for example, by performing mechanical processing using an end mill or the like on the surface of the printed wiring board 5. By grinding the surface of the printed wiring board 5, the thickness of the thin-walled portion 37c becomes thinner than the thicknesses of the first mounting portion 31 and the second mounting portion 33, making it easier to displace the connecting portion 35 in the thickness direction.

[0062] Furthermore, in addition to the structure that shortens the effective width of the connecting portion 35 or the structure that reduces the thickness of the connecting portion 35, a folded structure may be formed as described above. As shown in FIG. 10 , the folded structure includes a folded connection portion 39 that serves as a stress relief portion and connects the first mounting portion 31 and the second mounting portion 33. Two folded connection portions 39 are formed. The first mounting portion 31 and the second mounting portion 33 are connected by the two folded connection portions 39.

[0063] The first mounting portion 31 is formed by the seventh notch 41b. The folded structure is formed by the slit-shaped eighth notch 41c. The eighth notch 41c is formed in a manner that surrounds the connecting portion 35 except in the direction in which the first mounting portion 31 is located. Two folded connection portions 39 are formed in the portion of the printed wiring board 5 sandwiched between the seventh notch 41b and the eighth notch 41c. When the first mounting portion 31 is displaced in the thickness direction relative to the second mounting portion 33, stress generated in the printed wiring board 5 is alleviated by the two folded connection portions 39.

[0064] Furthermore, in order to displace the connecting portion 35 in the thickness direction, the connecting portion 35 may be temporarily heated to soften the resin of the connecting portion 35 (printed wiring board 5), thereby displacing the connecting portion 35 in the thickness direction. Alternatively, the connecting portion 35 may be heated to expand the resin, thereby displacing the connecting portion 35 in the thickness direction. The above-mentioned methods (or structures) may be combined as a method for displacing the connecting portion 35 in the thickness direction.

[0065] The folded structure may be a structure in which two folded connection portions 39 are formed by one folded structure, or a structure in which four folded connection portions 39 are formed by two folded structures.

[0066] 11, the first mounting portion 31 is formed (defined) by a slit-shaped ninth notch 41d and a tenth notch 41e. The first mounting portion 31 and the second mounting portion 33 are connected by two connecting portions 35.

[0067] The folded structure is formed by an eleventh notch 41f and a twelfth notch 41g. The eleventh notch 41f is formed relative to one connecting portion 35 in a manner surrounding the one connecting portion 35 except in the direction in which the first mounting portion 31 is located. The twelfth notch 41g is formed relative to the other connecting portion in a manner surrounding the other connecting portion 35 except in the direction in which the first mounting portion 31 is located.

[0068] On one side of the connecting portion 35, one folded connection portion 39 is formed in a portion of the printed wiring board 5 sandwiched between the ninth notch 41d and the eleventh notch 41f. Another folded connection portion 39 is formed in a portion of the printed wiring board 5 sandwiched between the tenth notch 41e and the eleventh notch 41f.

[0069] On the other connecting portion 35 side, one folded connection portion 39 is formed in a portion of the printed wiring board 5 sandwiched between the ninth notch 41d and the twelfth notch 41g. One folded connection portion 39 is formed in a portion of the printed wiring board 5 sandwiched between the tenth notch 41e and the twelfth notch 41g. When the first mounting portion 31 is displaced in the thickness direction relative to the second mounting portion 33, the stress generated in the printed wiring board 5 is alleviated by the four folded connection portions 39.

[0070] The electronic component 3 of the electronic device 1 according to the second embodiment can be attached to the heat dissipation member 7 in any manner that brings the electronic component 3 into thermal contact with the heat dissipation member 7 so that heat generated in the electronic component 3 can be effectively transferred to the heat dissipation member 7. For example, the electronic component 3 can be attached to the heat dissipation member 7 using an adhesive, screws, or the like.

[0071] In the electronic device 1 described above, the electronic component 3 and the heat dissipation member 7 are in thermal contact with each other via a thermally conductive adhesive sheet 43 acting as a TIM. The thermally conductive adhesive sheet 43 has a sticky or adhesive material applied to both sides of the sheet. The electronic component 3 is fixed to the heat dissipation member 7 by the thermally conductive adhesive sheet 43.

[0072] If a pressing pressure (biasing force) is required to secure the electronic component 3 to the heat dissipation member 7, a rivet 23 (see FIG. 1) or a spring may be used. Screws or the like may also be used as needed. When screws are used, the tightening pressure (tightening torque) must be adjusted to a level that does not cause damage or other effects to the electronic circuit components sealed in the sealing body 17 due to the tightening pressure.

[0073] As described above, in the electronic device 1, the first electronic component 3a and the second electronic component 3b, which are different in height, are mounted on the printed wiring board 5. The first electronic component 3a, which is relatively short in height from the printed wiring board 5, is mounted on the first mounting portion 31 on the printed wiring board 5. The second electronic component 3b, which is relatively tall in height from the printed wiring board 5, is mounted on the second mounting portion 33 on the printed wiring board 5.

[0074] The first mounting portion 31 and the second mounting portion 33 are connected via a connecting portion 35 that is deformable in the thickness direction. This allows the first mounting portion 31, on which the first electronic component 3a, which has a relatively small height, is mounted, to be closer to the heat dissipation member 7 than the second mounting portion 33, on which the second electronic component 3b, which has a relatively large height, is mounted. As a result, both the first electronic component 3a and the second electronic component 3b, which have different heights, can be in effective thermal contact with the heat dissipation member 7.

[0075] The electronic devices described in each embodiment can be combined in various ways as needed.

[0076] The embodiments disclosed herein are examples and are not intended to be limiting. The scope of the present disclosure is defined by the claims, not the scope described above, and is intended to include all modifications within the meaning and scope equivalent to the claims. [Industrial Applicability]

[0077] The present disclosure is effectively applied to electronic devices including electronic components and heat dissipation members. [Explanation of symbols]

[0078] 1 electronic device, 3 electronic component, 5 printed wiring board, 7 heat dissipation member, 9 pressing portion, 9a fixing portion, 9b pressing portion, 11 folded connection portion, 12 connection portion, 13a first notch, 13b second notch, 13c third notch, 13d fourth notch, 13e fifth notch, 15 step, 17 sealing body, 17a first main surface, 17b second main surface, 17c first side portion, 17d second side portion, 19 lead terminal, 19a first lead terminal, 19b second lead terminal, 21 temperature sensor, 23 rivet, 3a first electronic component, 3b second electronic component, 31 first mounting portion, 33 second mounting portion, 35 connecting portion, 37a V-groove, 37b opening, 37c thin portion, 39 folded connection portion, 41a 6th notch, 41b 7th notch, 41c 8th notch, 41d 9th notch, 41e 10th notch, 41f 11th notch, 41g 12th notch, 41h 13th notch, 43 Thermal conductive adhesive sheet, H1, H2 height.

Claims

1. A printed wiring board; one or more electronic components mounted on the printed wiring board, each having a first main surface and a second main surface facing each other; a heat dissipation member in thermal contact with the first main surface of the electronic component; and the printed wiring board includes a thickness direction deformation portion that allows deformation of the printed wiring board in a thickness direction, The electronic device, wherein the first main surface of the electronic component is in thermal contact with the heat dissipation member by the thickness direction deformation portion.

2. The electronic device according to claim 1 , wherein the thickness direction deformation portion includes a pressing portion that presses the first main surface of the electronic component against the heat dissipation member by an elastic force of the printed wiring board.

3. the pressing portion is defined in a band shape by a first notch and a second notch that are spaced apart from each other and extend in one direction, The pressing portion is a first fixing portion formed on one side of the band-shaped pressing portion and fixed to the heat dissipation member; a second fixing portion formed on the other side of the band-shaped pressing portion and fixed to the heat dissipation member; a pressing portion located between the first fixing portion and the second fixing portion; Including, 3. The electronic device of claim 2, wherein the first fixing portion and the second fixing portion are fixed to the heat dissipation member in a state in which the first main surface of the electronic component is pressed against the heat dissipation member by the elastic force generated by bending the pressing portion abutting the second main surface of the electronic component.

4. 4. The electronic device according to claim 3, wherein a spacer member is interposed between each of the first fixing portion and the second fixing portion and the heat dissipation member to adjust the distance between each of the first fixing portion and the second fixing portion and the heat dissipation member.

5. The electronic device according to claim 4 , wherein the spacer member includes a step portion formed on the heat dissipation member.

6. 6. The electronic device according to claim 3, wherein the printed wiring board is formed with a stress relief portion that relieves stress generated in the printed wiring board when the pressing portion is bent.

7. 7. The electronic device of claim 6, wherein the stress release portion includes a slit-shaped third notch formed to surround at least one of the corresponding first fixing portion and second fixing portion, except in the direction in which the pressing portion is located, relative to at least one of the first fixing portion and second fixing portion.

8. 4. The electronic device according to claim 3, wherein a temperature measuring circuit element is mounted on the pressing portion on a side opposite to the side facing the electronic component.

9. The electronic component is a first electronic component; a second electronic component; Including, The printed wiring board is a first mounting portion on which the first electronic component is mounted; a second mounting portion on which the second electronic component is mounted; and Including, the thickness-direction deformation portion includes a connection portion that connects the first mounting portion and the second mounting portion, the first mounting portion and the heat dissipation member are disposed at a first distance from each other, and the first main surface of the first electronic component is in thermal contact with the heat dissipation member; 2. The electronic device according to claim 1, wherein the second mounting portion and the heat dissipation member are arranged at a second distance apart, the second distance being different from the first distance, and the first main surface of the second electronic component is in thermal contact with the heat dissipation member.

10. The electronic device according to claim 9 , wherein the connecting portion has a groove formed therein, the groove extending in a direction intersecting a direction from the second mounting portion to the first mounting portion.

11. The electronic device according to claim 9 , wherein the connecting portion has perforated openings formed along a direction intersecting a direction from the second mounting portion to the first mounting portion.

12. The electronic device according to claim 9 , wherein the connecting portion has a thin portion formed therein that is thinner than the thickness of each of the first mounting portion and the second mounting portion.

13. 13. The electronic device according to claim 9, further comprising a stress relief portion formed thereon that relieves stress generated in the printed wiring board due to deformation of the connecting portion in the thickness direction.

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