Electronic device

Abstract

To provide an electronic device that can achieve both heat dissipation and heat retention.SOLUTION: An electronic device according to an embodiment includes a first portion, a second portion, and a thermal conductivity variable portion provided between the first portion and the second portion, the thermal conductivity state of which changes depending on temperature.SELECTED DRAWING: Figure 4

Description

[Technical Field]

[0001] FIELD OF THE INVENTION Embodiments of the present invention relate to electronic devices. [Background technology]

[0002] Electronic devices installed in cold regions or on aircraft are exposed to low temperatures, so their startup time can be shortened by warming up. On the other hand, when the ambient temperature is high, heat dissipation to the outside of the device must be ensured. Therefore, there is a demand for electronic devices that can both retain heat and dissipate heat. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Publication No. 2022-7173 [Patent Document 2] Japanese Patent Application Publication No. 2019-102662 Summary of the Invention [Problem to be solved by the invention]

[0004] The problem to be solved by the present invention is to provide an electronic device that can achieve both heat retention and heat dissipation properties. [Means for solving the problem]

[0005] The electronic device according to the embodiment includes a first section, a second section, and a thermal conduction variable section that is provided between the first section and the second section and whose thermal conduction state changes depending on temperature. [Brief explanation of the drawings]

[0006] [Figure 1] FIG. 1 is an explanatory diagram of an electronic device according to a first embodiment. [Figure 2] FIG. [Figure 3] FIG. 2 is an explanatory diagram showing a partial configuration of the electronic device. [Figure 4] FIG. 2 is a cross-sectional view showing the configuration of a thermal conduction variable section of the electronic device. [Figure 5] FIG. 10 is a cross-sectional view showing the configuration of a thermal conduction variable section of an electronic device according to a first modified example. [Figure 6] FIG. 2 is an explanatory diagram showing the structural formula of a bimetal. [Figure 7] FIG. 10 is a cross-sectional view showing the configuration of a thermal conduction variable section of an electronic device according to a second modification. [Figure 8] FIG. [Figure 9] 4 is a graph showing a heat conduction mode by the heat conduction variable unit. [Figure 10] FIG. 10 is an explanatory diagram showing the configuration of a thermal conduction variable section of an electronic device according to a third modification. [Figure 11] FIG. 2 is an explanatory diagram showing the formula for thermal conductivity. [Figure 12] 4 is a graph showing a heat conduction mode by the heat conduction variable unit. [Figure 13] FIG. 4 is an explanatory diagram showing the configuration of the thermal conduction variable section. [Figure 14] FIG. 10 is a cross-sectional view showing the configuration of a thermal conduction variable section of an electronic device according to a fourth modification. [Figure 15] FIG. [Figure 16] FIG. 13 is a cross-sectional view showing the configuration of a thermal conduction variable section of an electronic device according to a fifth modified example. [Figure 17] FIG. 13 is a cross-sectional view showing the configuration of a thermal conduction variable part of an electronic device according to a sixth modification. [Figure 18] 4 is a graph showing a heat conduction mode by the heat conduction variable unit. DETAILED DESCRIPTION OF THE INVENTION

[0007] An electronic device 1 according to one embodiment of the present invention will be described below with reference to FIGS. 1 to 4. FIG. 1 is an explanatory diagram of the electronic device 1 according to the first embodiment, and FIG. 2 is a cross-sectional view showing the configuration of the electronic device 1. FIG. 3 is an explanatory diagram showing the configuration of an assembly portion of a part of the electronic device, where the chassis 10 and the edge 21a of the substrate 21 are assembled. FIG. 4 is an explanatory diagram showing the configuration of the thermal conduction variable unit 40. For ease of explanation, each figure shows a schematic representation, enlarged, reduced, or omitted as appropriate. In the figures, arrows X, Y, and Z indicate three mutually orthogonal directions. As an example, the X axis indicates a position in which the electronic device is arranged along the first direction, the Y axis indicates a second direction, and the Z axis indicates a third direction.

[0008] The electronic device 1 includes, for example, a chassis 10 provided in a housing, a module 20, and a thermal conduction variable unit 40. For example, the electronic device 1 is a communication control device for an aircraft. In this embodiment, the substrate 21 of the module 20 is an example of a first part, and the chassis 10 is an example of a second part.

[0009] The chassis 10 has an opening for inserting, for example, the module 20, and is a housing that houses the module 20. For example, the chassis 10 includes a pair of rail portions 11 and an end frame 12 that connects the pair of rail portions 11, and is configured in a U-shape that opens to one side in the direction in which the module 20 is inserted.

[0010] The pair of rail portions 11 are arranged at both ends in a first direction along the width direction of the module 20. Each rail portion 11 extends in a second direction, which is the insertion direction. The pair of rail portions 11 have slit-shaped rail grooves 11a that face each other and open inward in the first direction. The rail grooves 11a of the rail portions 11 engage with edge portions 20a provided on both sides of the module 20, and guide the module 20 in the insertion direction.

[0011] The end frame 12 is provided with a connector 121. For example, the connector 121 is connected to and engaged with a connector 211 of the module 20.

[0012] The module 20 includes a substrate 21, a front cover 23 which is a cover member, a rear cover 24 which is also a cover member, and a retainer 25. For example, the electronic device 1 may have a plurality of modules 20 arranged therein.

[0013] The substrate 21 is, for example, a circuit board, and is configured in the shape of a plate having a pair of main surfaces. The front and back surfaces of the substrate 21 extend along a first direction and a second direction. For example, the substrate 21 has a substrate connector 211 on one end side. The substrate connector 211 is connected to a connector 121 on the chassis 10 side.

[0014] Furthermore, module components 212 such as various terminals and wiring, various electronic components, and heat dissipation components are mounted on the substrate 21. In this embodiment, sub-substrates may be arranged on the front and back of the substrate 21, respectively.

[0015] The module component 212 is a package component such as a BGA or LGA. The module component 212 is an electronic component having elements such as a processor or FPGA. The module component 212 may also include a heat dissipation component such as a heat dissipation plate or heat dissipation sheet that contacts both the electronic component and the covers 23 and 24.

[0016] The front cover 23 is a case member that covers one side in the third direction of the substrate 21. For example, the front cover 23 is made of a metal material and integrally includes a front wall portion that is arranged to face one side in the third direction of the substrate 21, and a front peripheral wall portion that surrounds the outer periphery.

[0017] The rear cover 24 is a case member that covers the other side in the third direction of the substrate 21. It is a case member that covers the outer periphery. For example, the rear cover 24 is made of a metal material and integrally includes a rear wall portion that faces the other side in the third direction of the substrate 21 and a rear peripheral wall portion that surrounds the outer periphery.

[0018] The retainer 25 is a rail body that protrudes laterally from the side edge of the module 20 .

[0019] The heat conduction variable unit 40 is provided between the module 20 side and the chassis 10 side, and changes its heat conduction characteristics (heat conduction state) by switching its contact state depending on the temperature. For example, the heat conduction variable unit 40 includes a first contact member 41 mounted on or connected to the module 20 side, and a second contact member 42 mounted on or connected to the chassis 10 side. As a specific example, the heat conduction variable unit 40 is provided, for example, at the edge portion 20a of the module 20, between the edges 21a on both sides of the substrate 21 and the chassis 10. For example, as shown in FIG. 3, a plurality of first contact members 41 are provided on the edges of the substrate 21, and a plurality of second contact members 42 are provided on the rail portion 11 at portions facing the substrate 21.

[0020] The contact members 41 and 42 are plate-shaped members made of a conductive material such as metal. The first contact member 41 and the second contact member 42 are thermally connected to each other, or thermally and mechanically, to form a heat path. The multiple contact members 41 and 42 may be in direct contact with each other, or may be indirectly connected via another member. The first contact member 41 and the second contact member 42 are arranged opposite each other in the width direction, and by deforming under thermal conditions, the contact state can be changed from a first state in which they are spaced apart to a second state in which they are in contact with each other.

[0021] For example, the first contact member 41 and the second contact member 42 are bimetal members formed by combining multiple members with different thermal properties. For example, the first contact member 41 and the second contact member 42 each have a deforming portion formed by bonding two different metal plates 411, 412, 421, 422 (e.g., alloys of iron, nickel, etc.) together in the thickness direction. The deforming portion deforms due to the different thermal expansion coefficients of the two types of metal plates 411, 412, 421, 422. The contact members 41, 42 are each supported in a cantilevered manner. That is, for example, in this embodiment, one end of the first contact member 41 in the width direction is a fixed end joined to a member on the board 21 side, and the other end is a free end. Similarly, the second contact member 42 has one end of the width direction that is a free end, and the other end is joined to a member on the chassis 10 side, such as the retainer 25. That is, the contact members 41, 42 are arranged opposite each other in the stacking direction, with the base end side serving as the support part and the tip end side serving as the free end being arranged on opposite sides. Of the two layers of these contact members 41, 42, the member with the higher thermal expansion coefficient is arranged on the outside in the opposing direction, so that when the temperature rises, the tip end portion serving as the free end is displaced toward the opposing contact members 42, 41 and bends and deforms so as to move closer, and when the temperature drops, the tip end portion moves in a direction away from each other.

[0022] The thermal conductivity of the thermal conductivity variable unit 40 changes depending on the deformation of these contact members 41, 42. That is, at low temperatures as shown in FIG. 4(a), there is no metallic contact and the space is sealed, so if the space is filled with a gas such as air, it functions as a heat insulator. Furthermore, if this space is a complete vacuum (absolute vacuum), thermal conduction cannot occur, and the thermal conductivity is extremely low in a low-pressure state. As shown in FIG. 4(b), as the temperature rises, the contact members 41, 42 deform and come into contact with the other contact members 42, 41. Furthermore, as the temperature rises, both contact members 41, 42 deform, increasing the contact area, and changing the thermal conductivity, as shown in FIG. 4(c). That is, for example, the contact state of multiple contact members 41, 42 changes depending on their deformation.

[0023] In the heat conduction variable section 40 configured as above, the heat conductivity of the edge 21a of the substrate 21 is low due to warm-up at low temperatures, and the heat conductivity of the edge 21a of the substrate 21 is high due to warm-up at high temperatures.

[0024] For example, FIG. 1(a) shows a plan view of the chassis 10, and FIG. 1(b) shows a plan view of the module 20. Also, FIG. 1(c) shows a plan view of the electronic device 1 in an assembled state with the module 20 inserted into the chassis 10. The assembly process for the electronic device 1 begins with covering the board 21, on which module components 212 such as electronic components are mounted, with the front cover 23 and the back cover 24, and then attaching a retainer 25 to the edge portion 20a to assemble the module 20. A heat conduction variable unit 40 is provided in one of the heat dissipation paths of the module 20. For example, a contact member 41 is bonded to the edge of the board 21, and a contact member 42 is bonded to the chassis 10 side. The heat conduction variable unit 40 is provided by assembling the edge of the board 21 to the chassis 10. The assembled module 20 is then inserted into the opening of the chassis 10. At this time, the outer widthwise portion of the retainer 25 is inserted into the groove 11a of the chassis 10 and guided along the insertion direction. Then, the module 20 is inserted deep into the chassis 10, and a connector 211 provided on the edge of the board 21 is inserted into a connector 121 of the chassis 10, thereby electrically connecting the module 20 and the chassis 10.

[0025] In the electronic device 1 configured as described above, the heat from the heat-generating components included in the module components 212 on the substrate 21 is exchanged through the connectors 121, 211, but most of the heat is dissipated from the edge 21a of the substrate 21 by the part that comes into contact with the retainer 25 when it is tightened (mainly a frame made of metal or the like).

[0026] The heat-generating component can be considered to be an assembly of composite materials as an electrical component including electronic components and substrate 21 (base material, resin, copper foil, laminate), etc. Generally, heat conduction in the planar direction is low, so heat propagates outward via front cover 23, back cover 24, and retainer 25, which form the machine frame. Generally, when retainer 25 is tightened, it is pressed firmly against rail portion 11 on the chassis 10 side, thereby ensuring thermal conductivity.

[0027] Here, the multiple contact members 41, 42 of the thermal conduction variable unit 40 are arranged facing each other at a distance, as shown in FIG. 4(a), under a first temperature condition, for example. Then, as the temperature rises, the contact members 41, 42 deform, moving closer to each other and coming into contact, as shown in FIG. 4(b). As the temperature rises further, the contact area increases, as shown in FIG. 4(c). At this time, the contact members 41, 42 are pressed against each other at their opposing surfaces, and are thermally connected. Therefore, at low temperatures, the warm-up time can be shortened due to the heat retention properties, and at high temperatures, the heat dissipation properties can be improved, and the amount of heat dissipation can be adjusted according to the temperature conditions.

[0028] The electronic device 1 and electronic module 20 according to the above-described embodiment include a heat conduction variable unit 40 having contact members 41 and 42 that deform relative to each other, thereby enabling variable thermal conductivity characteristics and achieving both heat dissipation and heat retention. Specifically, when electronic devices are installed in cold regions or on aircraft, they may be exposed to low temperatures. For example, the frequency of a crystal oscillator may drift depending on the temperature. Therefore, warming up (warming air) is required to shorten startup time. On the other hand, when the ambient temperature is high, heat dissipation to the outside of the device must be ensured. If the thermal conductivity is fixed, the design must consider the trade-off between heat retention and heat dissipation, but an optimal solution for this trade-off does not necessarily exist. In contrast, according to the above-described embodiment, the heat conduction variable unit 40 allows the thermal conductivity to be varied according to temperature. This allows for shorter warm-up time at low temperatures through heat retention, and at high temperatures, the heat dissipation can be adjusted by improving heat dissipation, even for highly integrated electronic components.

[0029] The present invention is not limited to the above-described embodiment, and various modifications can be made without departing from the spirit of the present invention.

[0030] For example, the specific configuration of the contact members 41, 42 in the heat conduction variable section 40, that is, the shape, dimensions, material, number and other conditions of the contact members 41, 42 are not limited to those in the above embodiment, and various shapes can be applied.

[0031] [Variation 1] 5 is a cross-sectional view showing a heat conduction variable unit 40A according to Modification 1. The heat conduction variable unit 40A has curved surfaces 41a, 42a formed on the surfaces of contact members 41, 42. The heat conduction variable unit 40A has curved surfaces 41a, 42a formed at the tip end, which is the free end of one of the pair of plate-shaped contact members 41, 42, and at the opposing portion of the other member that faces the tip end when in contact. As an example, the curved surface 41a is formed by a chamfer at the corner of the contact member 41 on the side opposing contact member 42. Furthermore, a recess having a curved surface 42a that contacts the curved surface 41a is formed at the middle of the opposing surface of contact member 42.

[0032] FIG. 6 is an explanatory diagram showing the structural formula of a bimetal.

[0033]

number

[0034]

number

[0035] According to the structural formula shown in FIG. 6, when initial contact begins, only the corners come into contact, resulting in a low amount of heat conduction. On the other hand, if one point of contact is used, it is possible to increase the contact area as shown in FIG. 6, but this would require an additional metal lamination process. According to this embodiment, the curved surfaces 41a and 42a allow the contact area of ​​the contact portion to be set, so that, for example, the initial conductivity can be determined arbitrarily. Furthermore, by forming the curved surfaces 41a and 42a, the contact area can be increased and alignment can be achieved. Note that the arrangement of the curved portions is not limited to this, and they may be arranged in multiple locations.

[0036] [Variation 2] For example, although the contact members 41 and 42 have a bimetal structure in the above embodiment, this is not limiting. Fig. 7 is a side view of a thermal conduction variable part 40B according to Modification 2, and Fig. 8 is a plan view of the thermal conduction variable part 40B.

[0037] The heat conduction variable unit 40B is provided between the module 20 side and the chassis 10 side, and changes its heat conduction characteristics depending on the temperature. For example, the heat conduction variable unit 40B includes a first contact member 41B mounted on or connected to the module 20 side, a second contact member 42B mounted on or connected to the chassis 10 side, and a guide member 43 that guides the movement direction. As a specific example, the heat conduction variable unit 40B is provided, for example, at the edge portion 20a of the module 20, between the edges 21a on both sides of the substrate 21 and the retainer 25. For example, the first contact member 41B is provided on the edge of the substrate 21, and the second contact member 42B is provided on the retainer 25 at a portion facing the substrate 21.

[0038] The contact member 41B includes a metal plate 413 having guide holes 413a formed at three or more points, and a coil spring 414 that is an elastic member connected to the metal plate 413.

[0039] The contact member 42B includes a metal plate 413 having guide holes 423a formed at three or more points, and a coil spring 424 connected to the metal plate 423. That is, the heat conduction variable part 40B includes coil springs 414 and 424 as deformation parts. The metal plates 413 and 423 are plate-like members made of a conductive material, and have guide holes 413a and 423a formed in three or more locations. The shaft-shaped guide member 43 is arranged to pass through the guide holes 413a and 423a of the metal plates 413 and 423 that are arranged opposite each other, thereby guiding the movement direction.

[0040] Of the metal plates 413 and 423, metal plate 413 of first contact member 41B is joined to a member on the board 21 side via coil spring 414. Second contact member 42B is joined to a member on the chassis 10 side, such as retainer 25, via coil spring 414. Metal plates 413 and 423 are arranged opposite each other, and move toward and away from each other as the coil springs expand and contract due to temperature changes. Note that, in order to control thermal conductivity with high precision, at least the regions where coil springs 414 and 424 are arranged may be placed under reduced pressure.

[0041] The heat conduction variable part 40B changes its heat conduction as the coil springs 414, 424 deform according to the temperature characteristics. That is, at low temperatures as shown in FIG. 7(a), there is no metal contact and the space is sealed, so if the space is a gas such as air, it functions as a heat insulator. Furthermore, if this space is a vacuum, heat conduction cannot occur. As shown in FIG. 7(b), as the temperature rises, the coil springs deform, and come into contact with the other contact members 42B, 41B, which changes the heat conductivity. That is, for example, the contact state of the multiple contact members 41, 42 changes as they deform with each other.

[0042] If springs with linear characteristics are used as the coil springs 414 and 424, the load is proportional to the deflection, so The spring load P [N], spring constant k [N / mm], and spring deflection σ [mm] are as follows: P=kσ (1) Transverse elastic modulus G [N / mm 2], material diameter d [mm], coil mean diameter D [mm], N α For a compression spring, the effective number of turns is: k=Gd 4 / 8N α D 3 It is generally known that (2) Here, G [N / mm 2 The coefficient of [ ] is temperature dependent and the constant changes, so the position is variable. Therefore, according to this embodiment, the thermal conductivity in the variable structure can be shown as a characteristic as shown in FIG. 9, and a heat dissipation path can be secured, so that warm air can be passed to adjacent modules during warm-up.

[0043] [Variation 3] It should be noted that a plurality of modules 20 and a plurality of thermal conductivity variable units 40 may be arranged. FIG. 10 is an explanatory diagram of an electronic device 1C according to Modification 3. As shown in FIG. 10, the electronic device 1C according to this embodiment includes a plurality of thermal conductivity variable units 40C. The plurality of thermal conductivity variable units 40C are joined to a common thermal diffusion spread 61 inside the substrate 21. Furthermore, the plurality of thermal conductivity variable units 40C are joined to a common thermal diffusion spread 62 outside the substrate 21. It should be noted that the arrangement of the plurality of thermal conductivity variable units 40C is not limited to parallel connection. For example, the plurality of thermal conductivity variable units 40C may be arranged in series. Alternatively, a plurality of units each having a plurality of thermal conductivity variable units 40C connected in series may be arranged in parallel.

[0044] Here, if the thermal resistance per unit is as shown in Figure 11, Q=A*λ(T h -T c ) / Li Then, the overall thermal conductivity Q total is the effective cross-sectional area (contact area) A i、 Thermal conductivity is λ i、 The temperature inside the board is T hi、 The temperature outside the board is T ci。 If the height of the heat conduction variable part 40C is Li,

[0045]

number

[0046] Here, i is the number of variable structures, ranging from 1 to N. L is the distance between the media, and if the mounting surfaces are parallel, Li = L. The temperature is constant due to the heat diffusion effect at the mounting part, and the distance L in the structure of Figure 11 can be considered to be almost constant.

[0047]

number

[0048] If the mounting surface is not parallel and L changes depending on the position, the values ​​can be calculated by adding them together as ΣLi for a parallel structure.

[0049] Fig. 12 is a graph showing the thermal conduction modes according to this embodiment, with the horizontal axis representing temperature and the vertical axis representing thermal conductivity. According to the structure shown in Fig. 10, by changing the coefficient, a heat dissipation mode, as shown in Fig. 12, can also be provided to prevent element damage in module 20 that has reached an unexpectedly high temperature. That is, by combining multiple heat conduction variable units 40, multiple transition regions can be set, and heat dissipation modes can be set between them.

[0050] For example, in a configuration with multiple modules 20, when an adjacent module 20 switches to heat dissipation mode to prevent element breakdown, the module does not immediately switch to heat dissipation mode, so the priority of conducted heat can be changed within the chassis 10.

[0051] FIG. 13 shows an example of the modes when multiple modules 20 are arranged in parallel in the chassis 10. According to this embodiment, each module 20 can operate in a different heat conduction mode when the temperature changes. Therefore, it is possible to provide a function that prioritizes heat dissipation from modules that are considered to be more susceptible to damage, and its heat retention at low temperatures contributes to a warm-up start. That is, for example, it is possible to dissipate heat from a high-temperature module 20 to warm up a low-temperature module 20.

[0052] According to this embodiment, a heat dissipation mode can be provided to prevent element breakdown, and multiple modules 20 can be flexibly switched between heat retention and heat dissipation.

[0053] [Variation 4] In the first embodiment, the orientation of the plate-shaped contact members 41, 42 is such that the surface direction of the contact members 41, 42 is along a plane perpendicular to the inward and outward direction of the substrate 21, but this is not limited to this. FIGS. 14 and 15 show a side view and a plan view, respectively, of a thermal conduction variable unit 40D according to Modification 4. For example, as another embodiment, as shown in FIGS. 14 and 15, the surface direction of the plate-shaped members may be raised by 90 degrees so as to be along the inward and outward direction of the substrate 21. According to this embodiment, the contact area can be increased, and thermal conduction performance can be improved.

[0054] [Variation 5] Furthermore, in the third embodiment, the heat conduction variable unit 40B has been configured such that a pair of flat metal plates 413, 423 are in contact with each other, but this is not limiting. For example, the heat conduction variable unit 40B may be connected via another member. Fig. 16 is an explanatory diagram showing a heat conduction variable unit 40E according to Modification 5. The metal plates 413, 423 according to this embodiment have link members 416, 426 on their opposing surfaces, and are arranged opposite each other via these link members 416, 426.

[0055] The outer surfaces of the link members 416, 426 have uneven portions. For example, the link member 426 on the second contact member 42E side has a convex portion 426a that protrudes toward the tip end, for example, at the center in the width direction, and the link member 416 on the first contact member 41E side has a concave portion 416a that recedes toward the base end, for example, at the center in the width direction, to receive the convex portion 426a. In other words, for example, the multiple contact members 41E, 42E each have an uneven portion having a concave or convex portion, and each include link members 416, 426 that engage with each other.

[0056] According to this embodiment, it is possible to ensure the contact area and improve the vibration resistance in the width direction, that is, it is possible to prevent misalignment in the width direction and improve robustness against vibration.

[0057] [Variation 6] Furthermore, the features of the above-described embodiments may be combined. Fig. 17 is an explanatory diagram showing the configuration of a thermal conduction variable unit 40F according to Modification 6. The thermal conduction variable unit 40F according to this embodiment includes contact members 41 and 42, which are bimetal members that undergo bending deformation depending on temperature conditions, and coil springs 414 and 424 that expand and contract depending on temperature conditions. In other words, the thermal conduction variable unit 40F is configured by combining the thermal conduction variable unit 40 according to the first embodiment with the coil springs 414 and 424 of the thermal conduction variable unit 40B of Modification 2.

[0058] By combining multiple structures in this way, the number of physical constants increases, making it possible to modify the curve of the transition region. According to this embodiment, the order of the transition region can be increased, and the amount of thermal conduction that is thermally dependent can be manipulated as shown in FIG. 18. That is, for example, when a complex characteristic with a large order is exhibited based on the relationship between temperature and frequency drift, the order can be increased by using multiple types of thermal conduction variable parts 40, 40B in combination, and a thermal conductivity that is suitable for the temperature characteristics of the electronic device 1 can be achieved.

[0059] Furthermore, the module 20 and the heat conduction variable units 40, 40A to 40F may be arranged in different directions, or multiple heat conduction variable units with different heat conduction conditions may be used in combination. The arrangement of the heat conduction variable units 40, 40A to 40F is not limited to the above embodiment and can be changed as appropriate. For example, the contact members 41, 42 may be arranged as appropriate on other components such as the front cover 23, the rear cover 24, the retainer 25, and the rail portion 11.

[0060] According to at least one of the embodiments described above, by providing the heat conduction variable parts 40, 40A to 40F that change the thermal conductivity, it is possible to achieve both heat retention and heat dissipation. can.

[0061] Although several embodiments of the present invention have been described, these embodiments are presented as examples and are not intended to limit the scope of the invention. These novel embodiments can be embodied in various other forms, and various omissions, substitutions, and modifications can be made without departing from the spirit of the invention. These embodiments and their modifications are included within the scope and spirit of the invention, and are also included in the scope of the invention and its equivalents as defined in the claims. [Explanation of symbols]

[0062] 1, 1C...electronic device, 10...chassis, 11...rail portion, 11a...rail groove, 121...connector, 12...end frame, 20...electronic module, 20a...edge portion, 21...board, 21a...edge, 23...front cover, 24...back cover, 25...retainer, 40, 40A to 40F...heat conduction variable portion, 41, 41B, 41E...contact member, 41a...curved surface, 42, 42B, 42E...contact member, 42a...curved surface 43...guide member, 61, 62...heat diffusion spread, 211...connector, 212...module component, 411...metal plate, 412...metal plate, 413...metal plate, 413a...guide hole, 414...coil spring, 416...link member, 416a...recess, 421...metal plate, 422...metal plate, 423...metal plate, 423a...guide hole, 424...coil spring, 426...link member, 426a...convex portion.

Claims

1. Part 1 and Part 2 and a thermal conduction variable section provided between the first section and the second section, the thermal conduction state of which changes depending on temperature.

2. The electronic device according to claim 1 , wherein the thermal conductivity variable section has a contact member whose contact state changes depending on temperature.

3. The electronic device according to claim 2 , wherein the contact member has a deformation portion that is deformed by temperature.

4. The electronic device according to claim 3 , wherein the deforming portion is a bimetallic member formed by bonding together a plurality of metal members having different thermal characteristics.

5. The electronic device according to claim 3 , wherein the deformation portion includes an elastic member that expands and contracts due to heat.

6. The electronic device according to claim 5 , wherein the elastic member is a coil spring.

7. the first part is a substrate on which electronic components are mounted, The electronic device of claim 2 , wherein the second part is a chassis that houses a module.

8. a retainer disposed between the edge of the substrate and the chassis; The electronic device of claim 7 , wherein the first portion is connected to an edge of the substrate and the second portion is connected to a retainer.

9. The module comprises: A substrate; an electronic component mounted on the substrate; a cover member that covers the substrate; The electronic device of claim 8 , comprising:

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