Flexible circuit board for a terminal device and terminal device

Abstract

The application provides a flexible circuit board for a terminal device and the terminal device. The flexible circuit board comprises a substrate layer, a conductive layer and two protective layers. One of the conductive layers is arranged on one side of the substrate layer along the thickness direction of the substrate layer, and one of the protective layers covers the conductive layer. At least one of the protective layers comprises a body protection part and at least one heat conduction protection part, both of which cover the corresponding conductive layer. Each heat conduction protection part has heat conduction performance and electrical insulation. At least part of the heat conduction protection parts of the flexible circuit board is used to be thermally coupled with a heat source of the terminal device, so that the heat generated by the heat source can be conducted to the conductive layer covered by the heat conduction protection part. The flexible circuit board of the application can improve the overall heat dissipation capacity of the terminal device, has high reliability, and is conducive to the lightweight and miniaturized design of the terminal device.

Description

Technical Field

[0001] This application relates to the field of terminal equipment, and in particular to a flexible circuit board for terminal equipment and the terminal equipment itself. Background Technology

[0002] With the development of technology, various terminal devices have gradually become an indispensable part of life. To improve user experience and device performance, terminal devices are becoming increasingly thinner and lighter, integrating higher-performance electronic components. However, these electronic components and batteries generate a significant amount of heat during operation, leading to higher heat dissipation requirements for terminal devices. Generally, terminal devices primarily achieve overall heat dissipation through the installation of heat dissipation structures. Common heat dissipation structures are specifically positioned around electronic components that generate a large amount of heat, effectively transferring heat to other cooler areas (such as metal backplates).

[0003] However, to meet the high heat dissipation demands of terminal devices, increasing the heat dissipation structure of these devices is detrimental to the utilization of internal space and the overall lightweight design. Furthermore, under the design requirements of thinner and lighter terminal devices, it is impossible to further improve the heat dissipation efficiency of the heat dissipation structure to ensure the overall heat dissipation performance. Therefore, maximizing the system's and device's heat dissipation performance under limited space conditions is one of the urgent technical problems to be solved.

[0004] In summary, existing technologies cannot improve the heat dissipation performance of terminal devices while meeting the requirements of thinness and lightness, resulting in poor reliability. Summary of the Invention

[0005] The flexible circuit board and terminal device provided in this application embodiment solve the problem that the terminal device in the prior art cannot improve its heat dissipation performance and has poor reliability under the requirement of thinness and lightness.

[0006] A first aspect of this application provides a flexible circuit board for a terminal device, including at least one substrate layer. The flexible circuit board further includes a conductive layer and a protective layer. The conductive layer is disposed on one side of the substrate layer along its thickness direction, and the protective layer covers and contacts the conductive layer. Alternatively, the flexible circuit board further includes at least two conductive layers and two protective layers. The substrate layer is disposed on one or both sides along its thickness direction with conductive layers, and the two protective layers respectively cover and contact the uppermost and lowermost conductive layers of the at least two conductive layers.

[0007] The protective layer, or at least one of the two protective layers, includes a main body protective portion and at least one thermally conductive protective portion, both of which cover the corresponding conductive layer. Furthermore, each thermally conductive protective portion is thermally conductive and electrically insulating. At least a portion of the thermally conductive protective portion of the flexible circuit board is used for thermal coupling with a heat source of the terminal device, allowing heat generated by the heat source to be conducted through the thermally conductive protective portion to the conductive layer it covers.

[0008] The flexible circuit board provided in this application embodiment includes a substrate layer, a conductive layer, and a protective layer. The conductive layer is used to realize the electrical connection function of the flexible circuit board. The substrate layer can ensure the structural strength of the flexible circuit board and has good flexibility. The protective layer covers the contact conductive layer, so that the conductive layer is protected from the influence of the external environment and ensures the insulation between lines, thereby ensuring the reliable performance of the flexible circuit board.

[0009] The protective layer includes at least one thermally conductive protection part, which has thermal conductivity and electrical insulation, enabling a portion of the protective layer on the flexible circuit board to have thermal conductivity. This allows it to thermally couple with the heat source of the terminal device and transfer heat to the conductive layer in that portion. In other words, the flexible circuit board with the thermally conductive protection part can participate in the overall heat dissipation process of the terminal device to meet the high heat dissipation requirements of the terminal device. The flexible circuit board can also conduct heat from the high-temperature area to the low-temperature area inside the terminal device through the thermally conductive protection part, thereby improving the system's heat dissipation capability.

[0010] Furthermore, in response to the trend of thinner and lighter terminal devices, and to address the high heat dissipation requirements of these devices, flexible circuit boards can be used to participate in overall heat dissipation. This does not occupy the originally compact internal space of the terminal device. Instead, the layout of the flexible circuit board in the terminal device increases the additional heat dissipation space. Specifically, by placing the heat-conducting area (which can be understood as the area where the thermal protection part is located) on the flexible circuit board near the heat source, the heat conducted to the conductive layer can be increased, and the heat dissipation space can also be increased, which helps to improve the overall heat dissipation capacity of the terminal device.

[0011] On the other hand, flexible circuit boards can efficiently dissipate heat in areas with high temperatures, thus taking on some of the heat dissipation needs in terminal devices. In other words, while meeting the heat dissipation needs of terminal devices, the heat dissipation efficiency of flexible circuit boards can be increased (e.g., by changing the material of the thermal protection part), which can reduce other heat dissipation structures in terminal devices to a certain extent, thus facilitating the thinner and smaller design of terminal devices.

[0012] Furthermore, the protective layer includes a thermally conductive protection section and a body protection section. The thermally conductive protection section has thermal conductivity, while the body protection section maintains good flexibility. This allows the flexible circuit board to maintain stable bending capability while possessing thermal conductivity, enabling flexible layout within the terminal device. Considering the compact space layout of terminal devices, the flexibility of the flexible circuit board can be utilized for spatial arrangement while meeting the basic functional requirements, thereby improving the heat dissipation efficiency of the terminal device. In addition, in one example, for a foldable terminal device, the thermal conductivity and bending performance of the flexible circuit board can solve the heat dissipation problem between different parts of the terminal device casing.

[0013] In summary, the flexible circuit board provided in this application embodiment has a thermally conductive protective part on its protective layer with good thermal conductivity, which can not only ensure the reliability of its own structure, but also improve the overall heat dissipation capacity of the terminal device. It has high reliability and is conducive to the thinner and smaller design of the terminal device.

[0014] In one possible implementation, the thermally conductive protection section includes a cover layer that covers the conductive layer corresponding to the contact, and electrically insulating thermally conductive particles are added to the cover layer.

[0015] By adopting the above solution, a covering layer with electrically insulating and thermally conductive particles is added to wrap the corresponding conductive layer, which makes the thermally conductive protection part have good thermal conductivity and ensures isolation between the circuits within the conductive layer, avoiding short circuits and interference, and improving the performance and reliability of the flexible circuit board.

[0016] In one possible implementation, the thermally conductive particles are inorganic non-metallic thermally conductive particles.

[0017] Using the above solution, inorganic non-metallic thermally conductive particles have good thermal conductivity and electrical insulation properties. They can improve the thermal conductivity of the cover layer while avoiding electrical connections between the lines within the conductive layer, thus improving the reliability of the flexible circuit board.

[0018] In one possible implementation, the thermally conductive particles are made of at least one of boron nitride, aluminum nitride, and aluminum oxide.

[0019] In one possible implementation, the cover layer contains thermally conductive particles of various shapes.

[0020] Using the above method, the covering layer formed by stacking various thermally conductive particles of different shapes can have higher thermal conductivity, thereby improving the thermal conductivity of flexible circuit boards.

[0021] In one possible implementation, the cover layer is an adhesive layer with added thermally conductive particles, and the adhesive layer is made of an adhesive. Alternatively, the cover layer includes an adhesive layer and a cover film stacked along its thickness direction, with the adhesive layer covering the corresponding conductive layer, and the cover film covering the side of the adhesive layer away from the corresponding conductive layer. Both the adhesive layer and the cover film contain thermally conductive particles, with the adhesive layer made of an adhesive and the cover film made of a resin material.

[0022] Using the above solution, the cover layer can be a single adhesive layer or a combination of adhesive layers and a cover film stacked sequentially, and all of them contain thermally conductive particles, which can improve the thermal conductivity of the cover layer and better wrap the conductive layer of the flexible circuit board, ensuring the structural reliability of the flexible circuit board.

[0023] In one possible implementation, the resin material includes at least one of: polyimide, epoxy resin, acrylic acid, polyester resin, polyurethane resin, polyvinylidene chloride, polydimethylsiloxane, polystyrene, low-density polyethylene, high-density polyethylene, polypropylene, polyetheretherketone, and polyvinyl chloride.

[0024] In one possible implementation, the main body protection unit has a window at the position corresponding to each heat-conducting protection unit in the protective layer, and the heat-conducting protection unit is embedded in the corresponding window and connected to the main body protection unit.

[0025] Using the above solution, the window on the main body protection section can be used to house the thermally conductive protection section, making the heat dissipation area on the flexible circuit board more targeted, thereby achieving efficient heat dissipation. On the other hand, opening the window facilitates the processing of the thermally conductive protection section. In addition, the thermally conductive protection section is connected to the main body protection section, ensuring no gaps at adjacent positions, thus preventing the conductive layer at that location from being exposed and improving the reliability of the flexible circuit board.

[0026] In one possible implementation, the thickness of each thermally conductive protective element in the protective layer is equal to the thickness of the main protective element.

[0027] By adopting the above solution, on the one hand, the thermal protection section can ensure the intact filling between the lines within the conductive layer, ensuring inter-line insulation, and can also cover the outer surface of the conductive layer, preventing the conductive layer from being affected by the external environment. At the same time, it reduces thermal resistance with a relatively low thickness. On the other hand, it makes the overall thickness of the protective layer relatively uniform, which makes it easier to control the thickness of the flexible circuit board and does not occupy too much space in the terminal device, which is conducive to the overall thin and light design.

[0028] In one possible implementation, the protective layer includes a plurality of thermally conductive protective portions spaced apart along the length of the flexible circuit board.

[0029] The above solution includes multiple thermally conductive protection parts, which can conduct heat dissipation in a targeted manner for different areas, transferring heat from areas with higher temperatures to areas with lower temperatures. This helps to improve the thermal conductivity of the flexible circuit board, thereby improving the overall heat dissipation capacity.

[0030] In one possible implementation, each of the two protective layers includes a body protection section and at least one thermally conductive protection section.

[0031] By adopting the above scheme, heat can be transferred from the thermally conductive part of one protective layer to the thermally conductive part of another protective layer in the thickness direction. This allows the flexible circuit board to conduct heat not only in the length direction but also in the thickness direction, increasing the heat dissipation path in the flexible circuit board and greatly improving its heat dissipation performance.

[0032] In one possible implementation, the orthographic projection of all thermally conductive protective elements in one of the two protective layers onto the other protective layer overlaps with at least a portion of the thermally conductive protective elements in the other protective layer.

[0033] By adopting the above solution, the heat dissipation path of the flexible circuit board in the thickness direction is shortened, thereby improving the heat dissipation capacity.

[0034] In one possible implementation, one part of the thermally conductive protection section of the flexible circuit board is used for thermal coupling with the heat source of the terminal device, and the other part of the thermally conductive protection section is used to conduct heat out of the flexible circuit board. This allows the heat generated by the heat source to be conducted through one part of the thermally conductive protection section to the conductive layer it covers and contacts, and then through the conductive layer to the other part of the thermally conductive protection section, and finally conducted out of the flexible circuit board.

[0035] By adopting the above solution, the flexible circuit board has a complete heat conduction path. That is, a part of the thermal protection part of the flexible circuit board can be thermally coupled to the heat source, and the heat can be discharged to another part of the thermal protection part through the conductive layer. This makes the flexible circuit board have better heat conduction and heat dissipation functions, which is conducive to increasing the heat conduction channels between electronic components in the terminal device and improving the overall heat dissipation capacity.

[0036] In one possible implementation, at least a portion of the outer surface of another thermally conductive protection portion is covered with an additional heat dissipation structure, which extends to the outer periphery of the thermally conductive protection portion.

[0037] By adopting the above solution, the thermal protection unit can also contact the heat source through an additional heat dissipation structure, or transfer the heat conducted by the thermal protection unit to a wider area with lower temperature through an additional heat dissipation structure, which is beneficial to improving the heat dissipation efficiency of the flexible circuit board, thereby improving the overall heat dissipation capacity.

[0038] In one possible implementation, at least one thermally conductive structure is provided between the conductive layers of different layers to achieve heat conduction between the conductive layers of different layers through the thermally conductive structure, wherein the flexible circuit board has vias at the positions corresponding to each thermally conductive structure for the corresponding thermally conductive structure to pass through.

[0039] By adopting the above scheme, a heat-conducting structure is set between the conductive layers of different layers, which can improve the heat conduction efficiency between conductive layers, increase the diversity of heat conduction paths of flexible circuit boards, and thus improve the heat dissipation efficiency of flexible circuit boards.

[0040] In one possible implementation, the heat-conducting structure is configured as a single-piece heat-conducting pillar, which may be solid or hollow. Alternatively, the heat-conducting structure may be configured as a split structure, comprising a conductive pillar and a heat-conducting pillar, to make the heat-conducting structure conductive. The conductive pillar may be hollow, and its outer surface may contact the wall of the corresponding via and the corresponding conductive layer. The heat-conducting pillar may pass through the hollow portion of the conductive pillar and may be solid or hollow, with the heat-conducting pillar contacting the inner surface of the conductive pillar, or the heat-conducting pillar contacting the inner surface of the conductive pillar and the corresponding conductive layer.

[0041] The above-mentioned scheme allows for diverse heat conduction structures and flexible layouts, enabling reasonable design of the layout and structure of the conductive layer. Furthermore, the heat conduction pillars are easy to manufacture.

[0042] In one possible implementation, the heat-conducting pillar is either electrically conductive or electrically insulating.

[0043] In one possible implementation, the heat-conducting pillar is made of copper, tin, thermal adhesive, or thermal resin.

[0044] Using the above method, copper, tin, thermally conductive adhesive, and thermally conductive resin all have good thermal conductivity, which can improve the thermal conduction efficiency of flexible circuit boards.

[0045] In one possible implementation, each conductive layer includes at least one signal transmission line, and the conductive layers of different layers have signal transmission lines that transmit the same signal and overlap in at least a portion of their regions. A conductive heat-conducting structure is provided between the overlapping regions of the signal transmission lines that transmit the same signal in the conductive layers of different layers.

[0046] By adopting the above scheme, when a conductive heat-conducting structure is provided between the signal transmission lines that transmit the same signal in different conductive layers, the heat-conducting structure can also be reused as the structure for interlayer electrical connection. This not only improves the heat dissipation efficiency of the flexible circuit board, but also facilitates processing and saves costs.

[0047] In one possible implementation, the thermal conductivity of the thermally conductive protection part is greater than or equal to 1.5 W / m·K.

[0048] By adopting the above solution, the thermally conductive protection section has good thermal conductivity, which is beneficial to improving the thermal conductivity efficiency of the flexible circuit board.

[0049] In one possible implementation, the body protection unit includes a cover layer that covers the conductive layer corresponding to the contact. No thermally conductive particles are added to the cover layer, and the body protection unit is configured as an electrically insulating, bendable protective structure.

[0050] By adopting the above solution, the cover layer of the main body protection part can protect the conductive layer of the flexible circuit board and has good flexibility, ensuring the realization of the basic functions of the flexible circuit board, adapting to the compact layout of the internal space of the terminal device, and is especially suitable for the ultra-high flexibility requirements of foldable terminal devices.

[0051] In one possible implementation, the flexible circuit board has at least one thermally conductive area and at least one bendable area arranged along its length direction. The thermally conductive area is the region where the thermally conductive protection portion of the flexible circuit board is located along its length direction, and the bendable area is the region where the body protection portion of the flexible circuit board is located along its length direction. All regions of each protective layer in the bendable area are body protection portions.

[0052] By adopting the above solution, the heat conduction area meets the heat conduction and heat dissipation requirements of the flexible circuit board, and the bendable area adapts to the spatial layout within the terminal device, especially to the ultra-high bendability requirements of foldable terminal devices, making the layout of the flexible circuit board more flexible and conducive to the thinner and lighter design of the terminal device.

[0053] A second aspect of this application provides a terminal device, including a housing and a plurality of electronic units mounted on the housing, and at least one flexible circuit board. Different electronic units are electrically connected to each other via the flexible circuit board. At least a portion of the flexible circuit board employs the flexible circuit board provided in the first aspect and any possible implementation thereof, and the flexible circuit board with a thermally conductive protection portion is a thermally conductive flexible circuit board. The terminal device also includes a heat source, and at least a portion of the thermally conductive protection portion of each thermally conductive flexible circuit board is thermally coupled to the heat source.

[0054] The terminal device provided in this application embodiment has at least a portion of flexible circuit boards with good thermal conductivity. That is, at least a portion of the flexible circuit boards are set as thermally conductive flexible circuit boards, which can not only ensure the reliability of its own structure, but also improve the overall heat dissipation capacity of the terminal device, and is conducive to the thinner and smaller design of the terminal device.

[0055] In one possible implementation, the terminal device further includes at least one heat dissipation structure in contact with a heat source; the thermally conductive protective portion of the thermally conductive flexible circuit board is in contact with the heat source or the heat dissipation structure.

[0056] By adopting the above solution, the heat source in the terminal device can directly contact the thermal protection part of the thermally conductive flexible circuit board, or contact it through the heat dissipation structure. Therefore, heat can be conducted to areas with high temperature, thereby improving the heat dissipation efficiency of the terminal device.

[0057] In one possible implementation, a thermal interface material layer is filled between the thermally conductive protection part and the heat source or heat dissipation structure, so that the thermally conductive protection part contacts the heat source or heat dissipation structure through the thermal interface material layer.

[0058] By adopting the above solution, the thermal interface material layer can reduce thermal resistance, conduct heat more quickly, and improve the heat dissipation efficiency in the terminal device.

[0059] In one possible implementation, the thermal interface material layer is made of thermally conductive grease, thermally conductive gel, or thermally conductive tape.

[0060] In one possible implementation, the heat source includes a battery mounted in a housing, and at least one portion of a thermally conductive flexible circuit board has a thermally conductive protection section in contact with the battery, the portion of which is used to dissipate heat from inside the thermally conductive flexible circuit board.

[0061] By adopting the above solution, a thermally conductive flexible circuit board can be set with a thermal protection section in the battery area. The large amount of heat generated during battery charging and discharging can be quickly conducted away by the thermally conductive flexible circuit board, thereby helping to improve the charging rate of the battery, enhance the heat dissipation capacity of the terminal device, and ensure the safety and reliability of the terminal device.

[0062] In one possible implementation, the battery has a core heat-generating area, and a portion of a thermally conductive flexible circuit board is in contact with the core heat-generating area of ​​the battery, while another portion of the thermally conductive flexible circuit board is in contact with the housing for dissipating heat from inside the thermally conductive flexible circuit board through the housing.

[0063] By adopting the above solution, the thermal protection unit can be set for the core heat-generating area of ​​the battery, and the heat can be directly conducted to the casing through the thermally conductive flexible circuit board, which greatly improves the overall heat dissipation efficiency of the terminal device.

[0064] In one possible implementation, the housing has a top region, a battery compartment region, and a bottom region arranged sequentially along the length of the terminal device. A battery is installed in the battery compartment region. The terminal device also includes a main circuit board disposed in the top region and a sub-circuit board disposed in the bottom region.

[0065] In this circuit, at least one end of a thermally conductive flexible circuit board is electrically connected to a main circuit board along its length direction, and the other end is electrically connected to a sub-circuit board. The thermally conductive flexible circuit board has a first bendable area, a thermally conductive area, and a second bendable area arranged sequentially along its length direction. The thermally conductive area has a thermally conductive protection portion on one side along its thickness direction that contacts the battery, and a thermally conductive protection portion on the other side that contacts the middle plate or rear cover of the housing. The first bendable area extends from the top region to the battery compartment region, and the second bendable area extends from the battery compartment region to the bottom region.

[0066] By adopting the above solution, the thermally conductive flexible circuit board can conduct a large amount of heat generated by the main circuit board to the casing and the secondary circuit board, as well as a large amount of heat generated by the battery to the casing and the secondary circuit board. This increases the heat dissipation path and space in the terminal device, and greatly improves the overall heat dissipation efficiency of the terminal device.

[0067] In one possible implementation, the thermally conductive flexible circuit board also has another thermally conductive area located outside the end of the second bendable area away from the thermally conductive area in the length direction of the thermally conductive flexible circuit board, and the other thermally conductive area is located in the bottom region of the housing; when the thermally conductive flexible circuit board includes an additional heat dissipation structure, the additional heat dissipation structure contacts the thermally conductive protection portion of the other thermally conductive area.

[0068] In one possible implementation, the heat source includes a main circuit board and at least one heat-generating device mounted on the main circuit board. The terminal device includes at least one heat dissipation structure in contact with the heat source, and the at least one heat dissipation structure includes a first heat dissipation structure in contact with at least one heat-generating device of the heat source.

[0069] In this embodiment, at least one portion of the thermally conductive flexible circuit board has a thermally conductive protection part in contact with the main circuit board and / or the first heat dissipation structure, and the portion of the thermally conductive protection part is used to conduct heat out of the interior of the thermally conductive flexible circuit board.

[0070] By employing the above solution, the thermally conductive flexible circuit board can conduct a large amount of heat generated by the main circuit board and the heat-generating devices mounted on it (e.g., system-on-a-chip, image processor, etc.) to cooler areas (e.g., the casing and sub-circuit board). This prevents the localized temperature in the area where the main circuit board is located from becoming too high, which could affect the reliability of the heat-generating devices in that area. Therefore, within a limited space, this significantly improves the system heat dissipation efficiency of the terminal device, contributing to higher intelligence, higher computing power, higher functional integration, and overall miniaturization. Furthermore, the thermally conductive flexible circuit board can contact more areas with higher temperatures; it can directly contact the main circuit board or conduct heat through the heat dissipation structure, increasing the heat dissipation pathways within the terminal device and further improving the overall heat dissipation efficiency.

[0071] In one possible implementation, the terminal device is a foldable terminal device, comprising multiple housings rotatably connected to adjacent housings via a pivot mechanism. The housings include a first housing and a second housing. A main circuit board is disposed in the first housing, and a sub-circuit board is disposed in the second housing. At least one thermally conductive flexible circuit board passes through the pivot mechanism between the first and second housings. One end of the thermally conductive flexible circuit board passing through the pivot mechanism is electrically connected to the main circuit board, and the other end is electrically connected to the sub-circuit board in the second housing. The area of ​​the thermally conductive flexible circuit board passing through the pivot mechanism is designated as a bendable area. Furthermore, a portion of the thermally conductive flexible circuit board with thermal protection is located in the first housing and contacts the main circuit board and / or a first heat dissipation structure; another portion of the thermally conductive flexible circuit board with thermal protection is located in the second housing, and / or in other housings located between the first and second housings, for dissipating heat from the interior of the thermally conductive flexible circuit board.

[0072] The above solution involves placing the main circuit board and its heat-generating components in the first housing (which can be understood as the main shell), resulting in higher heat levels in the first housing and relatively lower temperatures in other housings (which can be understood as secondary housings). By utilizing the thermal conductivity and bending performance of the thermally conductive flexible circuit board, the area passing through the pivot mechanism is designated as a bendable zone, exhibiting high bending performance under long-term dynamic bending conditions. Multiple thermally conductive zones are positioned at specific locations, with some zones' thermal protection components contacting the main circuit board and / or the first heat dissipation structure in the first housing. Other thermal protection components are located in the second housing and / or other housings (located between the first and second housings). Combined with the conductive layers in the bendable zones, a thermally conductive path is formed across the bendable zones. This allows heat from the higher-temperature first housing to be conducted through the thermally conductive flexible circuit board to the lower-temperature second housing and / or other housings between the first and second housings. This prevents excessive heat in the area where the main circuit board is located in the first housing from affecting its performance, improving the system heat dissipation performance of the foldable terminal device and increasing its reliability. Attached Figure Description

[0073] Figure 1a This is a three-dimensional structural diagram of the terminal device according to a first embodiment of this application;

[0074] Figure 1b This is an exploded structural diagram of the first embodiment of the terminal device according to this application;

[0075] Figure 1c This is a cross-sectional schematic diagram of the first embodiment of the terminal device of this application;

[0076] Figure 1d This is a second cross-sectional schematic diagram of the first embodiment of the terminal device according to this application;

[0077] Figure 2a This is a schematic diagram of the rear structure of the terminal device according to the first embodiment of this application (the back cover has been removed from the figure);

[0078] Figure 2b for Figure 2a A cross-sectional view along the AA direction, with the rear cover added to the diagram;

[0079] Figure 3 This is a schematic diagram showing the connection relationship between various components of the terminal device in an embodiment of this application;

[0080] Figures 4a-4f This is a top view schematic diagram illustrating different implementation methods of the flexible circuit board in the embodiments of this application;

[0081] Figure 5a for Figure 4a Cross-sectional schematic diagram of the first implementation method in the BB direction;

[0082] Figure 5b for Figure 4a A cross-sectional schematic diagram of the first implementation method in the CC direction;

[0083] Figure 6a This is a schematic diagram of the structure of a flexible circuit board in a reference design.

[0084] Figure 6b for Figure 6a A cross-sectional view along the A'-A' direction;

[0085] Figure 6c for Figure 6a A cross-sectional view along the B'-B' direction;

[0086] Figure 7a for Figure 4a Schematic diagram of the first implementation method in the BB direction (II);

[0087] Figure 7b for Figure 4a Schematic diagram of the cross section of the first implementation method in the CC direction (II);

[0088] Figures 8a-8d This is a cross-sectional schematic diagram of the thermally conductive area of ​​the flexible circuit board in an embodiment of this application;

[0089] Figure 9a This is a cross-sectional view along the length of a second implementation of the flexible circuit board according to an embodiment of this application.

[0090] Figure 9b This is a cross-sectional view along the width direction of a second implementation of the flexible circuit board according to an embodiment of this application;

[0091] Figure 9c This is a partial cross-sectional view along the length of the second implementation of the flexible circuit board according to an embodiment of this application;

[0092] Figure 9d This is a partial cross-sectional view along the length of a second implementation of the flexible circuit board according to an embodiment of this application. Figure 3 ;

[0093] Figure 10 This is a schematic cross-sectional view of another possible structure under the second implementation of the flexible circuit board in the embodiments of this application;

[0094] Figure 11a This is a partial cross-sectional schematic diagram of a third implementation of the flexible circuit board according to an embodiment of this application;

[0095] Figure 11b This is a partial cross-sectional schematic diagram of the third implementation of the flexible circuit board in this application;

[0096] Figure 12a This is a top view schematic diagram of the flexible circuit board thermal conductive structure according to an embodiment of this application;

[0097] Figure 12b This is a three-dimensional structural diagram of the flexible circuit board thermal conductive structure according to an embodiment of this application;

[0098] Figure 12c This is a schematic diagram of the layout of the signal transmission lines on the flexible circuit board according to an embodiment of this application;

[0099] Figures 13a-13d This is a partial cross-sectional schematic diagram of the thermal conductive structure of the flexible circuit board according to an embodiment of this application;

[0100] Figure 14a This is a schematic diagram showing the positional relationship of the thermally conductive flexible circuit board in the first embodiment of the terminal device of this application.

[0101] Figure 14b This is a schematic diagram of the heat dissipation path of the thermally conductive flexible circuit board in the first embodiment of the terminal device of this application.

[0102] Figure 15 This is a cross-sectional schematic diagram of the thermally conductive flexible circuit board in the first embodiment of the terminal device of this application.

[0103] Figure 16 This is a top view of the thermally conductive flexible circuit board in the first embodiment of the terminal device of this application.

[0104] Figure 17a This is a three-dimensional structural diagram of the second embodiment of the terminal device in the unfolded state according to the present application.

[0105] Figure 17bThis is a three-dimensional structural diagram of the second embodiment of the terminal device in the folded state according to the present application.

[0106] Figure 17c This is a schematic diagram of the rear structure of the terminal device according to the second embodiment of this application (the back cover has been removed from the figure);

[0107] Figure 18a This is a three-dimensional structural diagram of the terminal device in the folded state according to a third embodiment of the present application.

[0108] Figure 18b This is a schematic diagram of the rear structure of the terminal device according to the third embodiment of this application (the back cover has been removed from the figure);

[0109] Figure 19a This is a simplified structural diagram of the thermally conductive flexible circuit board layout in the second embodiment of the terminal device of this application.

[0110] Figure 19b This is a simplified structural diagram of the thermally conductive flexible circuit board layout in the second embodiment of the terminal device of this application.

[0111] Figure 20a This is a partial cross-sectional schematic diagram of the thermally conductive flexible circuit board in the second embodiment of the terminal device of this application.

[0112] Figure 20b This is a partial cross-sectional schematic diagram of the thermally conductive flexible circuit board in the second embodiment of the terminal device of this application.

[0113] Figure 20c This is a schematic cross-sectional view of another possible structure of the thermally conductive flexible circuit board in the second embodiment of the terminal device of this application.

[0114] Figure 20d This is a second possible cross-sectional view of the thermally conductive flexible circuit board in the second embodiment of the terminal device of this application.

[0115] Explanation of reference numerals in the attached figures:

[0116] Reference technology:

[0117] 4' Flexible circuit board; 41' Substrate layer; 42' Conductive layer; 43' Protective layer; 4323' Adhesive layer; 4324' Covering film.

[0118] This application:

[0119] 100. Terminal equipment;

[0120] 1. Housing; 101. Top area; 102. Battery compartment area; 103. Bottom area;

[0121] 11. Mid-frame; 111. Frame; 112. Mid-plate; 12. Back cover;

[0122] 13. Battery; 131. First Battery; 132. Second Battery; 133. Third Battery; 134. Core Heat Generation Area; 1341. Central Region;

[0123] 141. Main circuit board; 1411. CCM; 1412. SOC; 1413. Wi-Fi; 1414. PMU; 142. Secondary circuit board;

[0124] 15. Display screen; 151. First part; 152. Second part; 153. Foldable part;

[0125] 16. Board-to-board connectors;

[0126] 200. Foldable terminal devices;

[0127] 21. First housing; 22. Second housing; 23. Third housing; 3. Rotating shaft mechanism; 31. First rotating shaft mechanism; 32. Second rotating shaft mechanism;

[0128] 4. Flexible circuit board; 401. Main flexible circuit board; 402. Charge / discharge flexible circuit board; 403. Thermally conductive flexible circuit board;

[0129] 41. Substrate layer; 42. Conductive layer; 421. Ground signal transmission line; 422. Communication signal transmission line; 423. Current signal transmission line;

[0130] 43. Protective layer; 431. Body protection section; 4311. Covering layer; 4312. Window;

[0131] 432. Thermally conductive protection layer; 4321. Thermally conductive particles; 4322. Covering layer; 4323. Adhesive layer; 4324. Covering film;

[0132] 433, Bendable area; 4331, First bendable area; 4332, Second bendable area; 434, Heat-conducting area;

[0133] 44. Thermally conductive structure; 441. Thermally conductive pillar; 442. Electrically conductive pillar; 443. Perforated plate;

[0134] 45. Adhesive layer;

[0135] 51. First electronic unit; 52. Second electronic unit;

[0136] 6. Heat source; 61. Heat-generating device; 62. Heat dissipation structure; 621. First heat dissipation structure; 63. Additional heat dissipation structure; 64. Thermal interface material layer;

[0137] X: Length direction of the terminal device; Y: Width direction of the terminal device; Z: Thickness direction of the terminal device;

[0138] x, length direction; y, width direction; z, thickness direction. Detailed Implementation

[0139] The following specific embodiments illustrate the implementation of this application. Those skilled in the art can easily understand other advantages and effects of this application from the content disclosed in this specification. Although the description of this application will be presented in conjunction with some embodiments, this does not mean that the features of this application are limited to this embodiment. On the contrary, the purpose of describing the application in conjunction with embodiments is to cover other options or modifications that may be derived based on the claims of this application. To provide a thorough understanding of this application, many specific details will be included in the following description. This application may also be implemented without using these details. Furthermore, to avoid confusion or obscuring the focus of this application, some specific details will be omitted in the description. It should be noted that, unless otherwise specified, the embodiments and features in the embodiments of this application can be combined with each other.

[0140] It should be noted that in this specification, similar reference numerals and letters in the following figures indicate similar items. Therefore, once an item is defined in one figure, it does not need to be further defined and explained in subsequent figures.

[0141] In the description of the embodiments of this application, it should be noted that the terms "center," "upper," "lower," "left," "right," "vertical," "horizontal," "inner," "outer," "top," and "bottom," etc., indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings. They are only for the convenience of describing the embodiments of this application and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation. Therefore, they should not be construed as limitations on the embodiments of this application. In addition, the terms "first" and "second" are used for descriptive purposes only and should not be construed as indicating or implying relative importance.

[0142] In the description of the embodiments of this application, it should be noted that, unless otherwise explicitly specified and limited, the terms "installation," "connection," and "linking" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a mechanical connection or an electrical connection; they can refer to a direct connection or an indirect connection through an intermediate medium; and they can refer to the internal connection of two components. Those skilled in the art can understand the specific meaning of the above terms in the embodiments of this application based on the specific circumstances.

[0143] In the description of the embodiments of this application, it should be understood that "electrical connection" in the embodiments of this application can be understood as physical contact and electrical conduction between components; it can also be understood as the form in which different components in the circuit structure are connected through physical lines that can transmit electrical signals, such as copper foil of printed circuit board (PCB) or wires.

[0144] In the description of the embodiments of this application, it should be noted that the mutual perpendicularity in the embodiments of this application is not absolute perpendicularity. Approximate perpendicularity due to processing errors and assembly errors (e.g., the included angle between two structural features is 89.9°) is also within the range of mutual perpendicularity in the embodiments of this application. Similarly, the mutual parallelism in the embodiments of this application is not absolute parallelism. Approximate parallelism due to processing errors and assembly errors (e.g., the included angle between two structural features is 0.1°) is also within the range of mutual parallelism in the embodiments of this application. The axial symmetry in the embodiments of this application is not absolute axial symmetry. Approximate axial symmetry due to processing errors and assembly errors (e.g., a portion of the structure is offset by a certain distance or angle relative to the axis of symmetry) is also within the range of axial symmetry in the embodiments of this application. The central symmetry in the embodiments of this application is not absolute central symmetry. Approximate central symmetry due to processing errors and assembly errors (e.g., a portion of the structure is offset by a certain distance or angle relative to the axis of symmetry) is also within the range of central symmetry in the embodiments of this application. The embodiments of this application do not impose specific limitations on this.

[0145] To make the objectives, technical solutions, and advantages of the embodiments of this application clearer, the implementation methods of the embodiments of this application will be further described in detail below with reference to the accompanying drawings.

[0146] Current trends in terminal devices push towards thinner and lighter designs, requiring the integration of high-performance electronic components within limited space. This leads to increased heat generation from these components, constantly raising the heat dissipation requirements of the terminal devices and impacting their reliability. However, considering the high heat dissipation demands of these internal components, adding more internal cooling structures would occupy more space, hindering the thinner and lighter design. Furthermore, the trend towards thinner and lighter terminal devices makes it difficult to improve the heat dissipation efficiency of the cooling structure to enhance the overall cooling performance of the device.

[0147] To address the aforementioned issues, this application provides a flexible circuit board that not only ensures the reliability of its own structure but also enhances the overall heat dissipation capacity of the terminal device. It boasts high reliability and facilitates the lightweight and miniaturized design of the terminal device.

[0148] This application also provides a terminal device, which includes at least one flexible circuit board, wherein at least a portion of the flexible circuit board uses the flexible circuit board provided in this application.

[0149] It should be noted that the specific type of terminal device is not limited; the terminal device can be a mobile phone, tablet computer, wearable smartwatch, or other terminal devices. It should also be noted that the terminal device can be a non-foldable terminal device or a foldable terminal device; this application provides corresponding drawings and descriptions for both types of terminal devices. For ease of explanation and understanding, the structure and function of the terminal device will be specifically described below using a mobile phone as an example.

[0150] The following description will first use a non-foldable terminal device (e.g., a mobile phone) as the first embodiment.

[0151] Please see Figures 1a-2b , Figure 1a This is a three-dimensional structural diagram of the terminal device according to the first embodiment of this application. Figure 1b This is an exploded structural diagram of the first embodiment of the terminal device according to this application. Figure 1c This is a cross-sectional schematic diagram of the first embodiment of the terminal device according to this application. Figure 1d This is a second cross-sectional schematic diagram of the first embodiment of the terminal device according to this application. Figure 2a This is a schematic diagram of the rear structure of the terminal device according to the first embodiment of this application (the back cover has been removed from the figure). Figure 2b for Figure 2a A cross-sectional view along the AA direction. It should be noted that the accompanying drawings of this application embodiment are for illustrative purposes only, and the size and positional relationship of the components in the drawings do not represent the size and positional relationship of the components in the actual product. The terminal device may also include more or fewer components than shown in the drawings, and this application embodiment does not impose any limitations on this.

[0152] like Figures 1a-1c As shown, the terminal device 100 includes a housing 1 and a display screen 15. The housing 1 serves to protect the terminal device 100 and support the entire device. It has an internal space for housing the electronic components within the terminal device 100. The display screen 15 is disposed within the housing space and connected to the housing 1. The specific structure of the housing 1 will be described later in conjunction with the accompanying drawings.

[0153] Specifically, the display screen 15 is used to display images. The display screen 15 may be, but is not limited to, an organic light-emitting diode (OLED) display screen, an active-matrix organic light-emitting diode (AMOLED) display screen, or a quantum dot light-emitting diode (QLED) display screen, etc. The embodiments of this application do not limit the type and specific structure of the display screen 15.

[0154] like Figure 1b As shown, the terminal device 100 also includes a battery 13 and a circuit board installed within the housing 1. The battery 13 is a functional device that supplies power to the various electronic components in the terminal device 100, and it is typically connected to the circuit board. The battery 13 can be, for example, a lithium-ion battery, a nickel-cadmium battery, or a nickel-metal hydride battery; the specific type is not limited in this embodiment.

[0155] like Figure 1b As shown, the circuit board is the carrier for mounting and connecting electronic components in the terminal device 100. For example, the circuit board may have multiple functional modules to achieve corresponding functions, such as a charging management module, a power management module, a wireless communication module, an audio module, etc. This application embodiment does not limit this. The type of circuit board may be, for example, a PCB (printed circuit board), a flexible printed circuit board (FPC), etc., and this application embodiment does not limit this. Furthermore, one or more electronic components may be mounted on the circuit board, or electrically connected to other electronic components within the housing 1 via additional traces.

[0156] In one possible implementation, such as Figure 1b , Figure 2a and Figure 2b As shown, the housing 1 has a top region 101, a battery compartment region 102, and a bottom region 103 arranged sequentially along the length X of the terminal device. A battery 13 is installed in the battery compartment region 102. The terminal device 100 also includes a main circuit board 141 disposed in the top region 101 and a sub-circuit board 142 disposed in the bottom region 103. Both the main circuit board 141 and the sub-circuit board 142 are PCB boards.

[0157] Specifically, such as Figure 2aAs shown, the main circuit board 141 is the motherboard, primarily responsible for the computation of most system functions. In one example, the main circuit board 141 houses a Camera Compact Module (CCM) 1411, a System on Chip (SOC) 1412, a Wireless Fidelity (Wi-Fi) module 1413, and a Power Management Unit (PMU) 1414. The secondary circuit board 142 is the auxiliary board, primarily responsible for auxiliary functions such as audio signal transmission and signal connection processing. In one example, the secondary circuit board 142 houses a speaker, signal receiving components, etc. (not shown in the figure).

[0158] It should be noted that the main circuit board 141 can be located in the bottom region 103 of the housing 1, and the sub-circuit board 142 can be located in the top region 101 of the housing 1. This application embodiment does not limit this. Those skilled in the art will understand that when the terminal device is a foldable terminal device, there are multiple housings 1. The main circuit board 141 and the sub-circuit board 142 can be provided on the same housing 1, or the main circuit board 141 and the sub-circuit board 142 can be provided on a part of the housing 1, and other sub-circuit boards 142 can be provided on other parts of the housing 1, or the main circuit board 141 can be provided on a part of the housing 1, and the sub-circuit board 142 can be provided on other parts of the housing 1. The sub-circuit boards 142 located on different housings 1 are electrically connected to the main circuit board 141 through a rotating mechanism through which a flexible circuit board passes between different housings 1. The details will be described in detail below with reference to the accompanying drawings of the foldable terminal device.

[0159] The above mainly introduced the possible structures of the terminal device 100. The following text will elaborate on the specific structure of the housing 1.

[0160] It will be understood by those skilled in the art that the specific structure of the housing 1 is not limited. For example... Figure 1c and Figure 1d As shown, in one possible implementation, the housing 1 includes a middle frame 11, which includes a middle plate 112 and a frame 111. The frame 111 surrounds and connects to the outer periphery of the middle plate 112. The middle plate 112 supports the display screen 15 and the internal components of the terminal device 100. The frame 111 is a frame structure surrounding the outer periphery of the terminal device 100, and may include four sides surrounding the display screen 15 to help fix the display screen 15. In other possible implementations, the frame 111 may also include only three sides, two sides, etc., and this embodiment does not limit this.

[0161] Furthermore, the housing 1 may also include a back cover 12, also known as a battery cover, which is located on the back of the terminal device 100. The back cover 12, the mid-frame 11, and the display screen 15 can together form a closed enclosure to enclose the electronic components inside the terminal device 100, while also protecting against dust, impacts, and hardware scratches.

[0162] It should be noted that the back of the terminal device 100 can be understood as the side facing away from the user when the user uses the terminal device 100, that is, the surface of the terminal device facing away from the display screen in the thickness direction Z. The top area 101 of the housing 1 is the area where the top of the housing 1 is located when the user uses the terminal device 100, and the bottom area 103 of the housing 1 is the area where the bottom of the housing 1 is located when the user uses the terminal device 100.

[0163] In one possible implementation, such as Figure 1c As shown, the middle plate 112 of the middle frame 11 is reused as the back cover 12. Specifically, in the thickness direction Z of the terminal device, the display screen 15 is mounted on one side of the frame 111, and the middle plate 112 is connected to the other side of the frame 111 and serves as the back cover 12 of the terminal device 100. Alternatively, the entire middle frame 11 can be understood as having a "U-shaped structure" in cross-section. In this way, the middle plate 112 simultaneously performs the functions of both the middle plate 112 and the back cover 12, eliminating the need for an additional back cover 12, which helps save space and reduce the overall thickness and weight of the device.

[0164] It should be noted that the middle frame 11 can be a separate structure or a one-piece structure, and this application embodiment does not limit this. In one example, the middle frame 11 is a separate structure, that is, the middle plate 112 and the frame 111 are two different parts, which can be assembled together by snap-fit, fastening, or other means, and can be separated when disassembly is required. In another example, the middle frame 11 is a one-piece structure. Specifically, the middle plate 112 and the frame 111 of the middle frame 11 can be manufactured by one-piece molding or assembled by permanent connection methods such as welding, and this application embodiment does not limit this.

[0165] In other possible implementations, such as Figure 1d As shown, the middle plate 112 can also be spaced apart from the rear cover 12, i.e., the rear cover 12 can be set separately. Specifically, in the thickness direction Z of the terminal device, the middle plate 112 can be located in the middle of the frame 111, and the display screen 15 and the rear cover 12 are respectively mounted on both sides of the middle plate 112. In this way, both the middle plate 112 and the rear cover 12 can be used to mount devices, providing more mounting space for electronic components.

[0166] It should be noted that the connection method between the middle frame 11 and the back cover 12 is not limited in the embodiments of this application. In one example, the middle frame 11 and the back cover 12 are manufactured by integral molding or assembled by permanent connection methods such as welding.

[0167] like Figure 2a and Figure 2b In one possible implementation, the middle plate 112 has multiple regions, where different regions of the middle plate 112 are used to install different components. These different regions can be separated by structures such as stiffeners, which not only rationally divides the internal space of the terminal device 100 but also uses stiffeners and other structures to support and fix the components. It should be noted that this application embodiment does not limit the relative positions of the components within the terminal device 100.

[0168] The above mainly provides an exemplary description of the structure of housing 1. The following section will provide a detailed description of the function and possible location of the flexible circuit board in conjunction with the accompanying drawings.

[0169] Please see Figures 3-5b , Figure 3 This is a schematic diagram showing the connection relationship between various components of the terminal device in an embodiment of this application. Figures 4a-4f This is a top view of the flexible circuit board according to an embodiment of this application. Figure 5a for Figure 4a A cross-sectional schematic diagram of the first implementation method in the BB direction. Figure 5b for Figure 4a A cross-sectional schematic diagram of the first implementation method in the CC direction.

[0170] like Figure 2a and Figure 2b As shown, the terminal device 100 also includes a flexible circuit board 4. The flexible circuit board 4 is an important connection unit in the terminal device 100, enabling electrical connections between different electronic components and different circuit boards. Furthermore, the flexible circuit board 4 possesses excellent flexibility and bendability, allowing it to adapt to various complex spatial layouts and contributing to the miniaturization of the terminal device 100. The specific structure of the flexible circuit board 4 will be explained in detail later with reference to the accompanying drawings.

[0171] It should be noted that the number of flexible circuit boards 4 in the terminal device 100 is not limited, and the functions performed by each flexible circuit board 4 can be the same or different. Furthermore, the structures of each flexible circuit board 4 in the terminal device 100 can be the same or different, and their shapes and sizes can be the same or different. This application embodiment does not impose any restrictions on this.

[0172] The type of flexible circuit board 4 in the terminal device 100 is not limited. For example, it may include, but is not limited to, the main flexible circuit board 401, the charging and discharging flexible circuit board 402, the screen flexible circuit board, and the antenna flexible circuit board.

[0173] In one possible implementation, the main circuit board 141 and the secondary circuit board 142 are electrically connected via a flexible circuit board 4. This allows the flexible circuit board 4, with its good flexibility and bendability, to adapt to the compact internal space of the mobile phone while providing a stable electrical connection.

[0174] Specifically, such as Figure 2a and Figure 2b As shown, the main circuit board 141 and the secondary circuit board 142 are connected by a main flexible circuit board 401. The main circuit board 141 and the secondary circuit board 142 are connected by a charging and discharging flexible circuit board 402, which is used to connect the battery 13 to the main circuit board 141 and the secondary circuit board 142 and provide a power connection so that the battery 13 can be charged and discharged.

[0175] Furthermore, the display screen can be electrically connected to the main circuit board 141 via a flexible screen circuit board. The flexible screen circuit board is responsible for transmitting the display signals from the main circuit board 141 to the display screen, ensuring that images and videos can be clearly displayed on the display screen. In addition, the flexible screen circuit board can also transmit the control signals of the touch screen and feed back the user's touch operation to the motherboard to realize human-computer interaction.

[0176] It should be noted that the embodiments of this application do not limit the specific structure and position of the flexible circuit board for the screen, and those skilled in the art can set it reasonably according to design needs.

[0177] Those skilled in the art will understand that the terminal device 100 may also include various antennas, such as satellite communication antennas and cellular antennas. The main circuit board 141 is equipped with a radio frequency module (e.g., a radio frequency chip) corresponding to each antenna to transmit radio frequency signals to each antenna. Each antenna can also be connected to the main circuit board 141 via a flexible antenna circuit board (not shown in the figure), thereby establishing a connection with the corresponding radio frequency module.

[0178] It should be noted that the connection method of the flexible circuit board 4 is not limited. One possible implementation is as follows: Figure 2a and Figure 2bAs shown, the main circuit board 141 and the flexible circuit board 4, as well as the secondary circuit board 142 and the flexible circuit board 4, are electrically connected via board-to-board connectors 16 to ensure signal and power transmission and enhance the reliability and stability of the terminal device 100. In other possible implementations, the main circuit board 141, the secondary circuit board 142, and the flexible circuit board 4 can also employ surface mount technology (SMT). The flexible circuit board 4 can be directly soldered onto the surface of the circuit board without drilling holes. This allows for the integration of more electronic components within a smaller space, thereby achieving a miniaturized and thinner design for the terminal device 100.

[0179] It should be noted that the extension path and position of the flexible circuit board 4 are not limited and can be reasonably set according to the internal space of the terminal device 100. In one possible implementation, such as... Figure 2b As shown, the back cover of the housing 1 of the terminal device 100, the flexible circuit board 4, and the battery 13 are stacked sequentially in the thickness direction Z of the terminal device. The flexible circuit board 4 enables the electrical connection between the main circuit board 141 and the sub-circuit board 142. In other possible implementations, the flexible circuit board 4 can be inserted between the battery 13 and the middle frame 11 (see [reference]). Figure 14a The flexible circuit board 4 can be laid out more flexibly by utilizing its good bending properties.

[0180] like Figures 3-4a As shown, the terminal device 100 includes multiple electronic units mounted on a housing, and the different electronic units are electrically connected to each other via a flexible circuit board 4. It should be noted that this application embodiment does not limit the electronic devices of the multiple electronic units; the electronic devices of each electronic unit can be the same or different. In one possible implementation, the terminal device 100 includes a first electronic unit 51, a second electronic unit 52, and a third electronic unit (not shown in the figure). For example, the first electronic unit 51 includes, but is not limited to, a main circuit board 141 and first electronic devices integrated on the main circuit board 141 (CCM1411, SOC1412, Wi-Fi 1413, PMU1414, etc.); the second electronic unit 52 includes, but is not limited to, a sub-circuit board 142 and second electronic devices integrated on the sub-circuit board 142 (not shown in the figure); and the third electronic unit includes, but is not limited to, a display screen.

[0181] The preceding text primarily provided an illustrative description of the basic structure of the terminal device 100. It is understood that the terminal device generates a significant amount of heat during use. To prevent overheating and damage, which could affect reliability, the terminal device typically incorporates a heat dissipation structure. This structure transfers the heat generated by the heat source to cooler areas within the terminal device. The following text will explain the heat dissipation pathways within the terminal device 100 in conjunction with the accompanying drawings.

[0182] like Figure 2a and Figure 2b As shown, the terminal device 100 also includes a heat source 6, the specific type of which is not limited. In one possible implementation, the heat source 6 may include a main circuit board 141 and at least one heat-generating device 61 mounted on the main circuit board 141. The specific type of the heat-generating device 61 is not limited. In one possible implementation, at least one heat-generating device 61 may include at least one of a system-on-a-chip (i.e., SOC1412), a central processing unit, a charging chip, a general-purpose flash memory chip, an image processor, and a radio frequency chip. These heat-generating devices 61 generate a large amount of heat during operation, placing high demands on the heat dissipation performance of the main circuit board 141. In another possible implementation, the heat source 6 may also include a CCM1411 electrically connected to the main circuit board 141, the heat generated by which will also be concentrated in the area of ​​the main circuit board 141, affecting the reliability of the main circuit board 141 and surrounding devices.

[0183] In other possible implementations, the heat source 6 may include the battery 13, which also releases a large amount of heat during charging and use. This heat needs to be dissipated in a timely manner to ensure the stable and reliable operation of the terminal device 100.

[0184] like Figure 2a and Figure 2b As shown, the terminal device 100 may further include at least one heat dissipation structure 62 in contact with the heat source 6, wherein the at least one heat dissipation structure 62 includes a first heat dissipation structure 621 in contact with at least one heat-generating device 61 of the heat source 6. It is understood that the heat dissipation structure 62 can specifically dissipate the large amount of heat generated by the heat source 6 within the terminal device 100. In one possible implementation, such as... Figure 2b As shown, the SOC1412 (heat-generating device 61) on the main circuit board 141 can be in direct contact or thermally coupled with the first heat dissipation structure 621 to quickly dissipate the large amount of heat generated by the operation of the SOC1412 through the first heat dissipation structure 621 and conduct it to the back cover 12, or to a lower temperature area, such as the bottom area 103 where the sub-circuit board 142 is located.

[0185] It should be noted that the specific form of the heat dissipation structure 62 is not limited. In one possible implementation, the heat dissipation structure 62 may include at least one of a heat pipe, a graphene heat sink, a VC (vapor chamber) heat exchanger, and a ceramic heat sink. A graphene heat sink, due to the extremely high thermal conductivity of graphene, can quickly conduct heat from the heat source 6 to other parts of the terminal device, thereby achieving uniform heat dissipation of the terminal device 100. A VC (vapor chamber) heat dissipation structure 62 can evenly distribute heat on its surface, preventing the formation of hot spots, and can also be in direct contact or thermally coupled with the heat source 6, reducing thermal resistance and improving heat dissipation efficiency. It is understandable that increasing the area of ​​the heat dissipation structure 62 is beneficial to improving its heat dissipation efficiency, thereby improving the heat dissipation performance of the terminal device 100 and ensuring reliability.

[0186] However, terminal devices are trending towards thinner and smaller designs, while integrating higher-performance electronic components, leading to higher heat dissipation requirements. To address this, a heat dissipation structure 62 could be added inside the terminal device, or the thickness and contact area of ​​the heat dissipation structure 62 could be increased. However, this would inevitably occupy space, hindering the thinner and lighter design of the terminal device. Therefore, it is considered to create additional heat dissipation pathways within the terminal device, allowing more paths for heat to be transferred out, thereby improving the heat dissipation performance of the terminal device. The following section provides a brief introduction to a flexible circuit board 4 of a reference design, with reference to the accompanying drawings.

[0187] Please see Figures 6a-6c , Figure 6a This is a schematic diagram of the structure of a flexible circuit board in a reference design. Figure 6b for Figure 6a A cross-sectional view along the A'-A' direction. Figure 6c for Figure 6a A cross-sectional view along the B'-B' direction.

[0188] like Figures 6a-6c As shown, the flexible circuit board 4' includes a substrate layer 41', a conductive layer 42', and a protective layer 43'. The substrate layer 41' is the most basic structural layer of the flexible circuit board 4', typically made of polyimide (PI) or polyester (PET) material, possessing excellent flexibility, heat resistance, and mechanical strength. The protective layer 43' includes an adhesive layer 4323' and a cover film 4324'. Common materials for the cover film 4324' are PI or PET film, while the adhesive layer 4323' is made of epoxy resin and acrylic adhesives, etc. In other words, the outermost protective layer 43' or substrate layer 41' of the flexible circuit board 4' has low thermal conductivity, almost being thermally insulating. This means that the flexible circuit board 4' cannot effectively transfer most of the heat from electronic components and cannot meet the heat dissipation requirements of the functional components inside the terminal device.

[0189] Based on this, the present application provides a flexible circuit board with a thermally conductive protective part on its protective layer having good thermal conductivity, which can not only ensure the reliability of its own structure, but also improve the overall heat dissipation capacity of the terminal device. It has high reliability and is conducive to the thinner and smaller design of the terminal device.

[0190] The basic structure of the flexible circuit board 4 (which can be understood as the thermally conductive flexible circuit board 403) with thermally conductive protection part 432 is first introduced below. It should be noted that at least some of the flexible circuit boards 4 in the terminal device 100 mentioned above (e.g., the main flexible circuit board 401, the charging and discharging flexible circuit board 402, the screen flexible circuit board, the antenna flexible circuit board, etc.) can adopt the flexible circuit board 4 with thermally conductive protection part 432.

[0191] Please see Figures 7a-11b , Figure 7a for Figure 4a Schematic diagram of the cross section of the first implementation method in the BB direction, Part 2. Figure 7b for Figure 4a Schematic diagram of the cross section of the first implementation method in the CC direction, Part 2. Figures 8a-8d This is a cross-sectional schematic diagram of the thermally conductive area of ​​the flexible circuit board according to an embodiment of this application. Figure 9a This is a cross-sectional view along the length of a second implementation of the flexible circuit board according to an embodiment of this application. Figure 9b This is a cross-sectional view along the width of a second implementation of the flexible circuit board according to an embodiment of this application. Figure 9c This is a partial cross-sectional view along the length of the second implementation of the flexible circuit board according to an embodiment of this application. Figure 9d This is a partial cross-sectional view along the length of a second implementation of the flexible circuit board according to an embodiment of this application. Figure 3 , Figure 10 This is a schematic cross-sectional view of another possible structure in the second implementation of the flexible circuit board according to the embodiments of this application. Figure 11a This is a partial cross-sectional schematic diagram of the third implementation of the flexible circuit board in this application. Figure 11b This is a partial cross-sectional schematic diagram of the third implementation of the flexible circuit board in this application.

[0192] like Figure 5a , Figure 5b , Figures 9a-11bAs shown, the flexible circuit board 4 includes at least one substrate layer 41, a conductive layer 42, and a protective layer 43. The conductive layer 42 is disposed on one side of the substrate layer 41 along its thickness direction z, and the protective layer 43 covers and contacts the conductive layer 42. Alternatively, the flexible circuit board 4 may include at least two conductive layers 42 and two protective layers 43. The substrate layer 41 is disposed on one or both sides along its thickness direction z with conductive layers 42, and the two protective layers 43 respectively cover and contact the uppermost conductive layer 42 and the lowermost conductive layer 42 of the at least two conductive layers 42.

[0193] In other words, the flexible circuit board 4 includes a substrate layer 41, a conductive layer 42, and a protective layer 43. The conductive layer 42, composed of copper foil or other conductive metal materials, is used to realize the electrical connection function of the flexible circuit board 4 and is used to achieve electrical connections between electronic components. It should be noted that the embodiments of this application do not limit the interlayer structure or the number of layers of the conductive layer 42. In one possible implementation, the conductive layer 42 includes multiple conductive paths between its layers, which can transmit different electrical signals (e.g., data signals). The interlayer structure of the conductive layer 42 will be described later in conjunction with specific scenarios.

[0194] The substrate layer 41 is the foundation of the entire circuit board, ensuring the structural strength of the flexible circuit board 4 and providing good flexibility. It also possesses excellent electrical insulation properties and high-temperature resistance, capable of withstanding the heat generated by electronic components during operation. It should be noted that the thickness and material of the substrate layer 41 are not limited. In one possible implementation, the substrate layer 41 is made of flexible insulating materials such as polyimide (PI) or polyester (PET).

[0195] The protective layer 43 covers the contact conductive layer 42 and mainly serves to protect and insulate it. It is tightly bonded to the surface of the conductive layer 42 through a lamination process, so that the conductive layer 42 is protected from the influence of the external environment, such as dust and moisture, and ensures the insulation between lines, preventing the conductive layer 42 from short-circuiting with other conductors, thereby ensuring the reliable performance of the flexible circuit board 4.

[0196] Furthermore, in one possible implementation, such as Figure 9d , Figure 10 and Figure 11b As shown, the flexible circuit board 4 also includes an adhesive layer 45, which can tightly bond the substrate layer 41, the conductive layer 42, and the protective layer 43 together, ensuring the overall structural stability and reliability of the flexible circuit board 4. It should be noted that the position and structure of the adhesive layer 45 in the flexible circuit board 4 are not limited. In one example, such as... Figure 9d and Figure 10As shown, the flexible circuit board 4 includes two conductive layers 42. Each conductive layer 42 has a protective layer 43 and a substrate layer 41 disposed opposite to each other in the thickness direction z. The two substrate layers 41 disposed opposite to each other in the thickness direction z are bonded together by an adhesive layer 45, thereby improving the structural stability of the flexible circuit board 4. In another example, as... Figure 11b As shown, the flexible circuit board 4 includes three conductive layers 42. The adhesive layer 45 can be disposed between the substrate layer 41 and the protective layer 43, or it can be disposed between the substrate layer 41 and the protective layer 43. It is understood that those skilled in the art can reasonably set the adhesive layer 45 according to the requirements to ensure the structural stability of the flexible circuit board 4.

[0197] It should be noted that the material of adhesive layer 45 is not limited. In one example, adhesive layer 45 includes materials such as acrylic esters and epoxy resins, which can be cured at high temperatures to form a strong adhesive layer 45, so that the materials of each layer are tightly bonded together and jointly withstand external mechanical and electrical stresses.

[0198] It should be noted that this application does not limit the specific structure of the flexible circuit board 4. In one possible implementation, such as... Figure 5a and Figure 5b As shown, the flexible circuit board 4 includes a substrate layer 41, a conductive layer 42 and a protective layer 43 stacked sequentially in the thickness direction z. The protective layer 43 covers the conductive layer 42 on the side close to the substrate layer 41. That is, the protective layer 43 and the substrate layer 41 together completely wrap the conductive layer 42 to provide better protection and electrical insulation between the conductive layers 42.

[0199] It should be noted that, in one possible implementation, the thickness direction z can be the thickness direction z of the flexible circuit board 4, the thickness direction z of the substrate layer 41, or the thickness direction z of the conductive layer 42. This application embodiment does not limit this.

[0200] In another possible implementation, such as Figure 9a and Figure 9c As shown, the flexible circuit board 4 includes a protective layer 43, a conductive layer 42, a substrate layer 41, another conductive layer 42, and a protective layer 43 sequentially stacked in the thickness direction z. That is, the flexible circuit board 4 includes two conductive layers 42, and the substrate layer 41 has a conductive layer 42 disposed on both sides along its thickness direction z. The protective layer 43 covers the conductive layers 42 on both sides of the substrate layer 41 in the thickness direction z. In another example, as... Figure 10As shown, the flexible circuit board 4 includes two substrate layers 41, which are directly fixed by an adhesive layer 45. A conductive layer 42 is provided on one side of the substrate layer 41 along its thickness direction z (the side away from the other substrate layer 41). Two protective layers 43 respectively cover the uppermost conductive layer 42 and the lowermost conductive layer 42 in contact with the two conductive layers 42.

[0201] In another possible implementation, such as Figure 11a As shown, the flexible circuit board 4 includes two substrate layers 41, and conductive layers 42 are disposed on both sides of the substrate layers 41 in the thickness direction z. That is, the flexible circuit board 4 includes three conductive layers 42 and two protective layers 43, which respectively cover the uppermost and lowermost conductive layers 42 in contact with the two conductive layers 42. In another example, as... Figure 11b As shown, the flexible circuit board 4 includes three conductive layers 42 and three substrate layers 41, that is, one conductive layer 42 is provided for one substrate layer 41. Specifically, the substrate layers 41 and the protective layer 43 can be fixed and supported by adhesive layers 45. This application embodiment does not limit this.

[0202] It should be noted that, as Figures 9a-9d As shown, the two conductive layers 42 may or may not be electrically connected (see...). Figure 10 This application does not limit the scope of the embodiments.

[0203] Among them, such as Figure 5a , Figure 5b , Figure 9a and Figure 9bAs shown, at least one of the one or two protective layers 43 includes a main body protection portion 431 and at least one thermally conductive protection portion 432, both of which cover and contact the corresponding conductive layer 42. Furthermore, each thermally conductive protection portion 432 is thermally conductive and electrically insulating. At least a portion of the thermally conductive protection portion 432 of the flexible circuit board 4 is used for thermal coupling with the heat source 6 of the terminal device 100, allowing the heat generated by the heat source 6 to be conducted through the thermally conductive protection portion 432 to the conductive layer 42 it covers and contacts. In other words, the protective layer 43 of the flexible circuit board 4 includes at least one thermally conductive protection part 432. The thermally conductive protection part 432 has thermal conductivity and electrical insulation, so that a part of the protective layer 43 on the flexible circuit board 4 has thermal conductivity and can be thermally coupled with the heat source 6 of the terminal device 100, and transfer heat to the conductive layer 42 in that part of the region. Alternatively, the heat generated by the heat source 6 can be conducted through the thermally conductive protection part 432 to the conductive layer 42 inside the flexible circuit board 4, and then the heat can be conducted to the outside of the flexible circuit board 4 through the conductive layer 42 inside the flexible circuit board 4. In this way, the flexible circuit board 4 can participate in the overall heat dissipation process of the terminal device 100 to meet the high heat dissipation requirements of the terminal device 100. The flexible circuit board 4 can also conduct heat inside the terminal device 100 from the area with a higher temperature to the area with a lower temperature through the thermally conductive protection part 432, thereby improving the heat dissipation capability of the system.

[0204] It should be noted that thermal coupling refers to the ability to transfer heat between two components. For example, two components can directly contact each other to transfer heat and achieve thermal coupling, or they can transfer heat through an intermediate component (e.g., heat dissipation structure 62) to achieve thermal coupling.

[0205] Furthermore, in response to the trend of thinner and lighter terminal device 100 and to meet the high heat dissipation requirements of terminal device 100, the flexible circuit board 4 is used to participate in the overall heat dissipation. This does not occupy the original compact internal space of terminal device 100. Instead, the layout of the flexible circuit board 4 in terminal device 100 increases the additional heat dissipation space. That is, by setting the heat conduction area 434 (which can be understood as the area where the heat conduction protection part 432 is located) on the flexible circuit board 4 in the vicinity of the heat source 6, the heat conducted to the conductive layer 42 can be increased, and the heat dissipation space for heat conduction can also be increased, which is beneficial to improving the overall heat dissipation capacity of terminal device 100.

[0206] On the other hand, the flexible circuit board 4 can efficiently dissipate heat in areas with high temperatures, and it undertakes part of the heat dissipation needs in the terminal device 100. In other words, under the premise of meeting the heat dissipation needs of the terminal device 100, the heat dissipation efficiency of the flexible circuit board 4 can be increased (for example, by changing the material of the thermal protection part 432), which can reduce the number of other heat dissipation structures 62 in the terminal device 100 to a certain extent, which is conducive to the thinner and smaller design of the terminal device 100.

[0207] Furthermore, the protective layer 43 includes a thermally conductive protection part 432 and a main body protection part 431. The thermally conductive protection part 432 has thermal conductivity, while the main body protection part 431 maintains good flexibility. This ensures that the flexible circuit board 4 has both thermal conductivity and stable bending capability, allowing for flexible layout within the terminal device 100. This can be understood as, for example... Figure 4a , Figures 4c-4f As shown, the flexible circuit board 4 has at least one heat-conducting area 434 and at least one bendable area 433 arranged along its length direction x. The heat-conducting area 434 is the area where the heat-conducting protection part 432 of the flexible circuit board 4 is located along its length direction x, which can meet the heat conduction and heat dissipation requirements of the flexible circuit board 4. The bendable area 433 is the area where the body protection part 431 of the flexible circuit board 4 is located along its length direction x, and all areas of each protective layer 43 in the bendable area 433 are the body protection part 431. In this way, the flexible circuit board 4 can adapt to the spatial layout within the terminal device 100, especially to the ultra-high bendability requirements of foldable terminal devices, making the layout of the flexible circuit board 4 more flexible and conducive to the thin and light design of the terminal device 100. The specific structure of the bendable area 433 will be described in detail later in conjunction with the body protection part 431.

[0208] Therefore, considering the compact spatial layout of the terminal device 100, its flexibility can be utilized to improve the heat dissipation efficiency of the terminal device 100, while still fulfilling the basic functional requirements of the flexible circuit board 4. Furthermore, in one example, for the foldable terminal device 200, the heat dissipation problem between different casings within the foldable terminal device 200's housing can be solved through the thermal conductivity and bending performance of the flexible circuit board 4.

[0209] In summary, the flexible circuit board 4 provided in this application embodiment has a thermally conductive protection part 432 on its protective layer 43, which has good thermal conductivity. It can not only ensure the reliability of its own structure, but also improve the overall heat dissipation capacity of the terminal device 100. It has high reliability and is conducive to the thinner and smaller design of the terminal device 100.

[0210] It should be noted that, in one possible implementation, the length direction x can be the length direction x of the flexible circuit board 4, the length direction x of the substrate layer 41, or the length direction x of the conductive layer 42. This application embodiment does not limit this.

[0211] It should be noted that the heat dissipation path in the flexible circuit board 4 is not limited. In one possible implementation, such as... Figure 4a , Figure 9a and Figure 9c As shown, one portion of the thermally conductive protection section 432 of the flexible circuit board 4 is used for thermal coupling with the heat source 6 of the terminal device 100, while the other portion of the thermally conductive protection section 432 is used to conduct heat out of the flexible circuit board 4. This allows heat generated by the heat source 6 to be conducted through one portion of the thermally conductive protection section 432 to the conductive layer 42 it covers, and then through the conductive layer 42 to the other portion of the thermally conductive protection section 432, ultimately exiting the flexible circuit board 4. Alternatively, the heat generated by the heat source 6 can be understood as being conducted through one portion of the thermally conductive protection section 432 to the conductive layer 42 inside the flexible circuit board 4, and then through the conductive layer 42 to the other portion of the thermally conductive protection section 432, ultimately exiting the flexible circuit board 4 through the other portion of the thermally conductive protection section 432. In this way, the flexible circuit board 4 has a complete heat conduction path. That is, a part of the thermal protection part 432 of the flexible circuit board 4 can be thermally coupled to the heat source 6, and the heat can be discharged through the conductive layer 42 to another part of the thermal protection part 432. This makes the flexible circuit board 4 have better heat conduction and heat dissipation functions, which is beneficial to increase the heat conduction path between electronic devices in the terminal device 100 and improve the overall heat dissipation capacity.

[0212] Specifically, this application does not limit the specific location of the thermal protection part 432; those skilled in the art can configure it according to the heat dissipation requirements of the terminal device 100. In one possible implementation, the first electronic unit 51 and the second electronic unit 52 are electrically connected through the flexible circuit board 4, and, in addition to the areas where the first electronic unit 51 and the second electronic unit 52 are located, other areas on the flexible circuit board 4 are also provided with thermal protection parts 432. In one example, such as... Figure 4aAs shown, a thermally conductive protection part 432 can be provided in the area where the flexible circuit board 4 is electrically connected to the first electronic unit 51 (e.g., the main circuit board), so that heat can be quickly conducted into the flexible circuit board 4. The flexible circuit board 4 is also provided with a thermally conductive protection part 432 that is in direct contact with the heat source 6 (e.g., the battery) to achieve heat conduction. The first electronic unit 51 allows heat to be conducted through the flexible circuit board 4 to a lower temperature area, such as the area where the second electronic unit 52 is located. Furthermore, a thermally conductive protection part 432 can also be provided in the area where the flexible circuit board 4 is electrically connected to the second electronic unit 52, thereby improving the heat conduction efficiency.

[0213] In another example, such as Figure 4f As shown, the flexible circuit board 4 has a thermally conductive protection section 432 that is in direct contact with the heat source 6. This section can directly conduct the heat generated by the heat source 6 to another thermally conductive protection section 432, i.e., the area with a lower temperature, thereby improving heat transfer efficiency. At this time, the area between the two thermally conductive protection sections 432 is the area where the main body protection section 431 is located.

[0214] Furthermore, copper exposure can be applied at the location where the flexible circuit board 4 is electrically connected to the first electronic unit 51 (e.g., the main circuit board 141), or an additional heat dissipation structure 63 can be added (see...). Figure 3 This is to improve the heat dissipation capacity of the flexible circuit board 4, but this embodiment does not limit this. It is understood that the second electronic unit 52 can also perform corresponding processing, which will not be elaborated upon in this embodiment.

[0215] Furthermore, such as Figure 4a and Figure 4f As shown, the area where the thermal protection part 432 is located is the thermally conductive area 434. The flexible circuit board 4, in its length direction x, besides the thermally conductive area 434, mainly consists of the bendable area 433. It can be understood that the flexible circuit board 4 corresponding to the bendable area 433 has good flexibility, allowing it to adapt to the internal space of the terminal device 100 for flexible layout, especially in the application of the foldable terminal device 200. For example, as... Figure 4f As shown, the bendable area 433 can pass through the pivot mechanism of the foldable terminal device 200, and the flexible circuit board 4 can dissipate heat by setting multiple heat conduction areas 434, which can greatly improve its heat dissipation performance. The following text will also provide a detailed explanation in conjunction with the attached drawings.

[0216] It should be noted that, as Figure 4c As shown, the area where the flexible circuit board 4 is electrically connected to the first electronic unit 51 and the second electronic unit 52 may not have a thermal protection part 432, or, as... Figure 4dAs shown, the area where the flexible circuit board 4 is electrically connected to the first electronic unit 51 is not provided with a thermal protection part 432, while the area where the flexible circuit board 4 is electrically connected to the second electronic unit 52 is provided with a thermal protection part 432. This application embodiment does not limit this.

[0217] It is understandable that the first electronic unit 51 and the second electronic unit 52 can establish an electrical connection with the flexible circuit board 4 through the board-to-board connector 16. At this time, part of the heat generated by the first electronic unit 51 can be partially conducted into the flexible circuit board 4 through the board-to-board connector 16, and then conducted to the flexible circuit board 4 through the board-to-board connector 16. This is also one of the heat dissipation paths of the flexible circuit board 4. By setting the thermal protection part 432 in the area where the first electronic unit 51 and the second electronic unit 52 are located, the heat dissipation efficiency of the flexible circuit board 4 can be greatly improved, thereby improving the heat dissipation performance of the terminal device 100.

[0218] It is understandable that the flexible circuit board 4 does not have bending capability at the locations where the first electronic unit 51 and the second electronic unit 52 are electrically connected to the board-to-board connector 16.

[0219] In other possible implementations, such as Figure 4e As shown, the first electronic unit 51 and the second electronic unit 52 can be electrically connected to the flexible circuit board 4 through the board-to-board connector 16. At the same time, the large amount of heat generated by the first electronic unit 51 can also be conducted into the flexible circuit board 4 through the board-to-board connector 16. Furthermore, the flexible circuit board 4 is provided with a thermally conductive protection part 432 corresponding to the area where the first electronic unit 51 and the second electronic unit 52 are located, while other areas are not provided with thermally conductive protection parts 432. This allows the heat to be quickly conducted to the area where the second electronic unit 52 is located, which has a lower temperature.

[0220] The specific structure of the protective layer 43 will be described in detail below.

[0221] It should be noted that the structure of the protective layer 43 is not limited; in one possible implementation, such as... Figures 9a-9d As shown, each of the two protective layers 43 includes a body protection portion 431 and at least one thermally conductive protection portion 432. In this way, heat can be transferred from the thermally conductive protection portion 432 of one protective layer 43 to the thermally conductive protection portion 432 of the other protective layer 43 in the thickness direction z. This allows the flexible circuit board 4 to conduct heat not only in the length direction x, but also in its thickness direction z, increasing the heat dissipation path in the flexible circuit board 4 and greatly improving its heat dissipation performance.

[0222] It is understood that the number of thermally conductive protection portions 432 in the protective layer 43 is not limited in the embodiments of this application. In one possible implementation, the protective layer 43 includes a plurality of thermally conductive protection portions 432 spaced apart along the longitudinal direction x of the flexible circuit board 4. In one example, such as Figure 9c and Figure 9d As shown, the protective layer 43 is provided with two thermally conductive protection parts 432. In this way, each thermally conductive protection part 432 can conduct heat dissipation specifically for different areas (i.e., areas with higher temperatures), transferring heat from areas with higher temperatures to areas with lower temperatures. This helps improve the thermal conductivity of the flexible circuit board 4, thereby improving the overall heat dissipation capacity. In other possible implementations, the protective layer 43 may also include one thermally conductive protection part 432.

[0223] Furthermore, in one possible implementation, such as Figure 9a As shown, the orthographic projection of all thermally conductive protective portions 432 in one of the two protective layers 43 onto the other protective layer 43 overlaps with at least a portion of the thermally conductive protective portions 432 in the other protective layer 43. In this case, the heat dissipation path of the flexible circuit board 4 in the thickness direction z becomes shorter, improving heat dissipation capacity. In other possible implementations, the projections of the thermally conductive protective portions 432 disposed between different layers in the thickness direction z may not overlap; this embodiment does not impose such limitations.

[0224] The above text mainly describes the specific structure of the flexible circuit board 4 and the implementation of its heat dissipation function. The following text will introduce the specific structure of the thermal protection part 432.

[0225] It should be noted that this application does not limit the specific structure of the thermal protection part 432. For example... Figures 8a-8d As shown, the thermal protection part 432 includes a cover layer 4322, which covers the conductive layer 42 corresponding to the contact. Electrically insulating thermally conductive particles 4321 are added to the cover layer 4322, so that the thermal protection part 432 has good thermal conductivity and isolates the circuits within the conductive layer 42, avoiding short circuits and interference, and improving the performance reliability of the flexible circuit board 4.

[0226] It should be noted that the number of layers of the cover layer 4322 is not limited. The cover layer 4322 can be a single adhesive layer 4323, or it can be an adhesive layer 4323 and a cover film 4324 stacked sequentially. All of them contain thermally conductive particles 4321, which can improve the thermal conductivity of the cover layer 4322 and better wrap the conductive layer 42 of the flexible circuit board 4, ensuring the structural reliability of the flexible circuit board 4.

[0227] In one possible implementation, such as Figure 8a and Figure 8cAs shown, the cover layer 4322 is an adhesive layer 4323 with added thermally conductive particles 4321, and the material of the adhesive layer 4323 is an adhesive. The adhesive with added thermally conductive particles 4321 can be understood as a thermally conductive adhesive; that is, the thermally conductive protection part 432 is made of thermally conductive adhesive. Thermally conductive adhesive is an adhesive with thermal conductivity and is widely used in electronic devices, electronic heat dissipation, optoelectronic devices, and other fields. It improves its thermal conductivity by filling it with thermally conductive materials (such as ceramic particles).

[0228] In other possible implementations, such as Figure 8b and Figure 8d As shown, the cover layer 4322 includes an adhesive layer 4323 and a cover film 4324 stacked along its thickness direction z. The adhesive layer 4323 covers and contacts the corresponding conductive layer 42, and the cover film 4324 is disposed on the side of the adhesive layer 4323 away from the corresponding conductive layer 42. Both the adhesive layer 4323 and the cover film 4324 contain thermally conductive particles 4321. The adhesive layer 4323 is made of an adhesive, and the cover film 4324 is made of a resin material. The resin containing the thermally conductive particles 4321 can be understood as a thermally conductive resin.

[0229] Thermally conductive resin is a resin material with high thermal conductivity. Its thermal conductivity is typically achieved by adding thermally conductive fillers (i.e., thermally conductive particles 4321) to the resin matrix. Thermally conductive resins are manufactured by adding thermally conductive fillers to the resin. These fillers form thermally conductive pathways within the resin, allowing the resin to effectively conduct internally generated heat to the outside.

[0230] The thermal conductivity of thermally conductive resins depends primarily on the type, shape, distribution, and interfacial interaction with the resin matrix of the filler. For example, boron nitride / graphene composite fillers can significantly improve the thermal conductivity of epoxy resins while maintaining good electrical insulation properties. Furthermore, the performance of thermally conductive resins can be further improved by optimizing the amount and dispersibility of the filler.

[0231] Furthermore, the resin material is not limited. Specifically, the resin material may include at least one of the following: polyimide (PI), epoxy resin (EP), acrylic acid (AA), polyester resin (PET), polyurethane resin (PES), polyvinylidene chloride (PVDF), polydimethylsiloxane (PDMS), polystyrene (PS), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polyetheretherketone (PEEK), and polyvinyl chloride (PVC).

[0232] Those skilled in the art will understand that the material of the thermally conductive particles 4321 is not limited. In one possible implementation, the thermally conductive particles 4321 are inorganic non-metallic thermally conductive particles 4321. Because inorganic non-metallic thermally conductive particles 4321 have good thermal conductivity and electrical insulation properties, they can improve the thermal conductivity of the cover layer 4322 while avoiding electrical connections between the intralayer lines of the conductive layer 42, thereby improving the reliability of the flexible circuit board 4. In one example, the material of the thermally conductive particles 4321 includes at least one of boron nitride, aluminum nitride, and aluminum oxide.

[0233] Furthermore, the shape of the thermally conductive particles 4321 is not limited. In one possible implementation, such as Figure 8a and Figure 8d As shown, the cover layer 4322 contains various shapes of thermally conductive particles 4321, such as spherical, rod-shaped, irregularly shaped, or sheet-like particles. This allows the cover layer 4322, formed by stacking various shapes of thermally conductive particles 4321, to have higher thermal conductivity, thus improving the thermal conductivity of the flexible circuit board 4. Specifically, the thermally conductive particles 4321 are sheet-shaped or angular, giving them a higher thermal conductivity coefficient and improving the thermal conductivity of the flexible circuit board 4. In other possible implementations, the thermally conductive particles 4321 in the cover layer 4322 can also be particles of a single shape, as long as they are thermally conductive; this embodiment does not limit this.

[0234] It should be noted that the size of the thermally conductive particles 4321 is not limited. In one possible implementation, such as... Figure 8a and Figure 8d As shown, when the line width and line spacing of each line in the conductive layer 42 are both 50μm, the diameter of the heat-conducting particle 4321 (which can be understood as the maximum size of the heat-conducting particle 4321) should be less than 25μm, so that the heat-conducting particle 4321 will not interfere with or wear the lines between the conductive layers 42, thus ensuring the structural reliability of the flexible circuit board 4.

[0235] It should be noted that when the interlayer lines of conductive layer 42 are filled with a cover layer 4322 or an adhesive layer 4323 containing thermally conductive particles 4321, it is still necessary to ensure that the inter-line insulation between the interlayer lines of conductive layer 42 is greater than or equal to 10. 8 Ω ensures the stability of signal transmission in the conductive layer 42, thereby improving the reliability of the flexible circuit board 4.

[0236] It is understood that the thermally conductive protection part 432 acquires thermal conductivity by filling it with different thermally conductive particles 4321. Both the thermal conductivity of the thermally conductive particles 4321 themselves and their shape can improve thermal conductivity. In one possible implementation, the thermal conductivity of the thermally conductive protection part 432 is greater than or equal to 1.5 W / m·K. In this case, the thermally conductive protection part 432 has good thermal conductivity, which is beneficial to improving the thermal conductivity efficiency of the flexible circuit board 4. It should be noted that the thermal conductivity of the thermally conductive protection part 432 can also be less than 1.5 W / m·K. For example, the thermal conductivity of thermally conductive adhesives has a wide range, typically between 0.8 and 3.6 W / m·K. Therefore, thermally conductive adhesives with high thermal conductivity can be selected. Through the combined effect of the thermally conductive protection part 432 in the flexible circuit board 4 and other heat dissipation structures 62 in the terminal device 100, the heat dissipation performance of the terminal device can also be improved. This application embodiment does not limit this.

[0237] In one possible implementation, the thermally conductive protection portion 432 is in contact with the heat source 6 (e.g., battery 13) or the heat dissipation structure 62. Those skilled in the art will understand that, in the case of a flexible circuit board 4 having multiple thermally conductive protection portions 432, some of the thermally conductive protection portions 432 may be in contact with the heat source 6, and some of the thermally conductive protection portions 432 may be in contact with the heat dissipation structure 62.

[0238] It should be noted that the thermally conductive protection part 432 can directly contact the heat source 6 (e.g., battery 13) or the heat dissipation structure 62, or it can contact the heat source 6 or the heat dissipation structure 62 through the thermal interface material layer 64. This application embodiment does not limit this.

[0239] In one possible implementation, such as Figure 7a and Figure 7bAs shown, a thermal interface material layer 64 is filled between the thermally conductive protection part 432 and the heat source 6, so that the thermally conductive protection part 432 contacts the heat source 6 through the thermal interface material layer 64. In this way, the thermal interface material layer 64 can reduce thermal resistance, conduct heat more quickly, and improve the heat dissipation efficiency within the terminal device 100. Furthermore, the type of thermal interface material is not limited. In one example, the thermal interface material layer 64 is made of thermally conductive tape. During the processing of the flexible circuit board 4, the thermally conductive tape can be used for shape fixing and has self-adhesive fixing ability, which is most conducive to processing and installation. However, to ensure heat dissipation efficiency, the thermal conductivity of the thermal interface material must be greater than that of the thermally conductive protection part 432. In another example, the thermal interface material layer 64 is made of thermally conductive gel. In this case, the structural bonding strength is high and the thermal conductivity is good. In yet another example, the thermal interface material layer 64 is made of thermally conductive silicone grease. The thermal conductivity of thermally conductive silicone grease is better than that of tape. Therefore, those skilled in the art need to choose according to the specific application. In other possible implementations, a thermal interface material layer 64 may be filled between the thermally conductive protection part 432 and the heat dissipation structure 62 so that the thermally conductive protection part 432 contacts the heat dissipation structure 62 through the thermal interface material layer 64.

[0240] The following section describes the heat-conducting structure 44 in the flexible circuit board 4.

[0241] Please see Figures 12a-13d , Figure 12a This is a top view schematic diagram of the flexible circuit board thermal conductive structure according to an embodiment of this application. Figure 12b This is a three-dimensional structural diagram of the flexible circuit board thermal conductive structure according to an embodiment of this application. Figure 12c This is a schematic diagram of the layout of the signal transmission lines on the flexible circuit board according to an embodiment of this application. Figures 13a-13d This is a partial cross-sectional schematic diagram of the thermal conductive structure of the flexible circuit board according to an embodiment of this application.

[0242] like Figures 9a-9d , Figure 11a and Figure 12b As shown, in one possible implementation, at least one heat-conducting structure 44 is provided between the conductive layers 42 of different layers to achieve heat conduction between the conductive layers 42. The flexible circuit board 4 has vias at the positions corresponding to each heat-conducting structure 44 for the corresponding structure to pass through. In other words, according to the heat conduction requirements of the terminal device 100, different conductive layers 42 in the flexible circuit board 4 can form interlayer heat conduction paths through the heat-conducting structures 44. This improves the heat conduction efficiency between the conductive layers 42, increases the diversity of heat conduction paths in the flexible circuit board 4, and thus enhances the heat dissipation efficiency of the flexible circuit board 4.

[0243] It should be noted that the number of heat-conducting structures 44 is not limited; it can be one, two, or three. Alternatively, the flexible circuit board 4 may not have heat-conducting structures 44. Those skilled in the art can set them reasonably according to design needs.

[0244] It should be noted that the heat-conducting structure 44 can be disposed between two conductive layers 42 to achieve heat conduction, or it can be disposed between three or four conductive layers 42 to achieve heat conduction. This application embodiment does not limit this.

[0245] In one example, the heat-conducting structure 44 is configured as a one-piece heat-conducting pillar 441, such as... Figure 13a As shown, the heat-conducting pillar 441 has a solid structure, and the heat-conducting structure 44 has better heat transfer efficiency. Or, as... Figure 13b As shown, the heat-conducting column 441 adopts a hollow structure, which is not a limitation of this application. The integral structure of the heat-conducting column 441 can be understood as the heat-conducting structure 44 being conductive or electrically insulating, which is not a limitation of this embodiment.

[0246] In another example, such as Figure 13c and Figure 13d As shown, the heat-conducting structure 44 is configured as a split structure, including a conductive pillar 442 and a heat-conducting pillar 441, so that the heat-conducting structure 44 is conductive. The conductive pillar 442 adopts a hollow structure, and the outer surface of the conductive pillar 442 contacts the wall surface of the corresponding through hole and the corresponding conductive layer 42. The heat-conducting pillar 441 passes through the hollow part of the conductive pillar 442 and adopts a solid structure (see...). Figure 13c ) or hollow structure (see Figure 13d Furthermore, the heat-conducting pillar 441 is in contact with the inner surface of the conductive pillar 442, or the heat-conducting pillar 441 is in contact with the inner surface of the conductive pillar 442 and the corresponding conductive layer 42. In this way, the conductive pillars 442 are in complete contact with each other, which can improve the heat conduction efficiency.

[0247] The specific form of the heat-conducting structure 44 is not limited. For example, when the lines of the conductive layer 42 are narrow, i.e., the line width cannot meet the processing requirements of the heat-conducting structure 44 (line width - hole diameter < 0.1 mm), a perforated plate 443 can be provided at the heat-conducting structure 44. The perforated plate 443 can be inserted between different conductive layers 42 to provide a fixing function, ensuring the structural reliability of each line of the conductive layer 42. Preferably, the difference between the diameter of the perforated plate 443 and the diameter of the heat-conducting structure 44 should be greater than or equal to 0.1 mm.

[0248] It should be noted that the conductive layer 42 may or may not have a perforated plate 443 in the area of ​​the heat-conducting structure 44 (i.e., line width - hole diameter ≥ 0.1 mm), and this embodiment does not impose any restrictions on this. The heat-conducting structure 44 has various forms and flexible layouts, and can be reasonably set according to the layout and structure of the conductive layer 42. Furthermore, the heat-conducting pillars 441 are easy to process and implement.

[0249] It should be noted that when there are multiple heat-conducting structures 44 in the flexible circuit board 4, the specific structures of the heat-conducting structures 44 at different locations can be the same or different. For example, all heat-conducting structures 44 can adopt an integrated structure or a split structure, or some heat-conducting structures 44 can adopt an integrated structure and some heat-conducting structures 44 can adopt a split structure. This application embodiment does not limit this.

[0250] It should be noted that the heat-conducting pillar 441 can be conductive or electrically insulating, and this application embodiment does not limit this. In one possible implementation, such as Figure 13a and Figure 13b As shown, the heat-conducting pillar 441 is conductive. In this case, the metal vias between the conductive layers 42 in the FPC can be reused as the heat-conducting structure 44, thereby saving costs.

[0251] Furthermore, the material of the heat-conducting pillar 441 is not limited. For example, when the heat-conducting pillar 441 is conductive, the material of the heat-conducting pillar 441 is copper or tin; when the heat-conducting pillar 441 is conductive, the material of the heat-conducting pillar 441 is thermally conductive adhesive or thermally conductive resin. In this way, copper, tin, thermally conductive adhesive, and thermally conductive resin all have good thermal conductivity, which can improve the heat conduction efficiency of the flexible circuit board 4.

[0252] It should be noted that the specific location of the heat-conducting structure 44 is not limited.

[0253] It is understandable that, such as Figure 12c As shown, the flexible circuit board 4 has at least one conductive layer 42, and the lines within the layer can transmit different signals. That is, each conductive layer 42 includes at least one signal transmission line, including some or all of the following: ground signal transmission line 421, communication signal transmission line 422, and current signal transmission line 423. When there are multiple conductive layers 42, electrical signal connections can also be achieved between different conductive layers 42 through metal vias. That is, different conductive layers 42 have signal transmission lines that transmit the same signal and at least partially overlap.

[0254] In one possible implementation, a conductive thermally conductive structure 44 is provided between the overlapping areas of signal transmission lines transmitting the same signal in different conductive layers 42. For example, the thermally conductive structure 44 can be provided by openings in the substrate layer 41 between current signal transmission lines 423 transmitting the same current signal or ground signal transmission lines 421 transmitting the same ground signal, and the thermally conductive structure 44 is conductive. With this approach, when a conductive thermally conductive structure 44 is provided between signal transmission lines transmitting the same signal in different conductive layers 42, the thermally conductive structure 44 can also be reused as a structure for interlayer electrical connections. This improves the heat dissipation efficiency of the flexible circuit board 4, facilitates manufacturing, and saves costs.

[0255] For example, such as Figure 12c As shown, a conductive heat-conducting structure 44 can be provided between the communication signal transmission line 422 in the first conductive layer 42 and the communication signal transmission line 422 in the second conductive layer 42 that transmits the same communication signal. A conductive heat-conducting structure 44 can be provided between the ground signal transmission line 421 in the first conductive layer 42 and the ground signal transmission line 421 in the second conductive layer 42 that transmits the same ground signal. A conductive heat-conducting structure 44 can be provided between the current signal transmission line 423 in the first conductive layer 42 and the current signal transmission line 423 in the second conductive layer 42 that transmits the same current signal.

[0256] It should be noted that, in one possible implementation, the overlapping area of ​​the signal transmission lines transmitting the same signal is greater than or equal to 0.3 mm, and the maximum aperture density is 11 apertures / mm. 2 While improving heat dissipation performance, structural reliability is also taken into account.

[0257] In other possible implementations, the electrically insulating heat-conducting structure 44 can be disposed between different conductive layers 42, evenly spaced, or interspersed around the heat-conducting structure 44 which has conductivity in different conductive layers 42. This application embodiment does not limit this.

[0258] The above mainly describes the heat-conducting structure 44 in the flexible circuit board 4 by way of example. The following will describe the body protection part 431 in the flexible circuit board 4.

[0259] like Figure 4a and Figure 4b As shown, the protective layer 43 also includes a body protection section 431. It can be understood that, apart from the thermally conductive protection section 432 provided for the heat dissipation requirements of the terminal device 100, the remaining areas of the protective layer 43 are all body protection sections 431.

[0260] In one possible implementation, such as Figure 4a and Figure 4bAs shown, in the protective layer 43, the main body protection part 431 has windows 4312 at the positions corresponding to each thermally conductive protection part 432. The thermally conductive protection part 432 is embedded in the corresponding window 4312 and is connected to the main body protection part 431. That is to say, the window 4312 on the main body protection part 431 can be used to set the thermally conductive protection part 432, making the heat dissipation area on the flexible circuit board 4 more targeted, thereby achieving efficient heat dissipation. On the other hand, opening the window 4312 is beneficial to the processing of the thermally conductive protection part 432. In addition, the thermally conductive protection part 432 is connected to the main body protection part 431, so that there is no gap between the two adjacent positions, thereby preventing the conductive layer 42 at that position from being exposed, improving the reliability of the flexible circuit board 4.

[0261] It should be noted that the size and shape of the window 4312 are not limited in this embodiment. In one possible implementation, such as... Figure 4a As shown, the main body protection section 431 can make a window of an appropriate size for the local area where the heat source 6 is located, and then fill the window 4312 of the main body protection section 431 to form a thermally conductive protection section 432. At this time, the main body protection section 431 can be left around the thermally conductive protection section 432, so that the projection of the heat source 6 in the thickness direction z is exactly located in the area of ​​the main body protection section 431, which can conduct the heat generated by the heat source 6 through the flexible circuit board 4 in a timely manner, thereby improving the heat dissipation efficiency of the terminal device 100.

[0262] In other possible implementations, such as Figure 4b As shown, the thermal protection part 432 does not have a main body protection part 431 on both sides in the width direction y, that is, the main body protection part 431 is interrupted. At this time, the flexible circuit board 4 has a larger thermal conduction area and the processing is simple, which is conducive to saving costs.

[0263] In this context, the width direction y is perpendicular to the length direction x and the thickness direction z.

[0264] Furthermore, the thickness of the main body protection portion 431 is not limited. In one possible implementation, the thickness of each thermally conductive protection portion 432 in the protective layer 43 is equal to the thickness of the main body protection portion 431. That is, in the protective layer 43, the outer surface of each thermally conductive protection portion 432 is aligned with the outer surface of the adjacent main body protection portion 431. It should be noted that the outer surfaces of the thermally conductive protection portions 432 and the main body protection portions 431 can be understood as surfaces exposed to the outside of the flexible circuit board 4. They can also be understood as surfaces away from the corresponding conductive layer 42 in the thickness direction z. With this structure, on the one hand, the thermally conductive protection portion 432 can ensure the complete filling between the lines within the conductive layer 42, ensuring inter-line insulation, and can also cover the outer surface of the conductive layer 42, preventing the conductive layer 42 from being affected by the external environment. At the same time, it reduces thermal resistance with a lower thickness. On the other hand, it makes the overall thickness of the protective layer 43 relatively uniform, which makes it easier to control the thickness of the flexible circuit board 4, and will not occupy too much space in the terminal device 100, which is beneficial to the overall thin and light design.

[0265] In one possible implementation, such as Figure 5a As shown, the main body protection unit 431 includes a cover layer 4311 that covers the conductive layer 42 corresponding to the contact. No thermally conductive particles 4321 are added to the cover layer 4311, and the main body protection unit 431 is configured as an electrically insulating, bendable protective structure. In this way, the cover layer 4311 of the main body protection unit 431 can protect the conductive layer 42 of the flexible circuit board 4 and has good bendability, ensuring the realization of the basic functions of the flexible circuit board 4, adapting to the compact layout of the internal space of the terminal device, and is especially suitable for the ultra-high bendability requirements of foldable terminal devices.

[0266] Furthermore, the specific structure of the main body protection part 431 is not limited. In one possible implementation, the covering layer 4311 of the main body protection part 431 is an adhesive layer (not shown in the figure). In other possible implementations, the covering layer 4311 of the main body protection part 431 includes an adhesive layer and a cover film 4324, which can uniformly wrap the conductive layer 42 and play a good protective and insulating role. This application embodiment does not limit this. The material of the cover film 4324 is not limited. In one possible implementation, the cover film 4324 is made of PI-based or PET-based material, which has good bending ability. In other possible implementations, the cover film 4324 may also be made of at least one of the following: epoxy resin (EP), acrylic acid (AA), polyurethane resin (PES), polyvinylidene chloride (PVDF), polydimethylsiloxane (PDMS), polystyrene (PS), low-density polyethylene (LDPE), high-density polyethylene (HDPE), polypropylene (PP), polyetheretherketone (PEEK), and polyvinyl chloride (PVC).

[0267] The above mainly describes the specific structure of the flexible circuit board 4. The following text will introduce the fabrication method of the flexible circuit board 4.

[0268] 1. Prepare the substrate: Select a suitable substrate and copper foil, and clean and treat the substrate to remove surface impurities.

[0269] 2. Drilling: Drilling through holes or positioning holes into the substrate to facilitate subsequent wiring and assembly. Drilling methods include, but are not limited to, mechanical drilling and laser drilling.

[0270] 3. Copper plating: Increases the thickness of the copper foil, improves conductivity and mechanical strength, and ensures the reliability and stability of the circuit.

[0271] 4. Etching: Remove unwanted metal layers to expose the substrate. After a stripping process, the desired circuit pattern is formed.

[0272] 5. Press-bonded protective layer: The thermosetting adhesive between the protective layer and the board is cured by high temperature and high pressure pressing to achieve a tight bond. In addition, windows are preset on the protective layer for setting up thermally conductive protection parts.

[0273] 6. Press-fit thermal protection part: First, the thermal protection part is shaped and then the semi-cured thermal protection part is pressed onto the window of the main body protection part. In one possible implementation, the outer dimensions of the thermal protection part are ≥ the size of the window on the protective layer + 0.2mm, which can reduce the risk of copper leakage in the conductive layer and improve the reliability of the flexible circuit board.

[0274] The thermal protection component includes, but is not limited to, the following processing methods:

[0275] 1) The thermally conductive protection part adopts the form of a semi-cured film, which is pressed into the window of the main body protection part by high temperature;

[0276] The following conditions must be met:

[0277] fake temperature ≤110℃ Pressing conditions Temperature 160–200℃, pressure 60–150 kgf, time 30–300 s Curing conditions Temperature 120–180℃, 60–120 min

[0278] The temporary bonding temperature refers to the temperature used during the flexible circuit board manufacturing process when temporarily bonding the cover film or pure adhesive film (in this case, the thermally conductive protective part in the form of a semi-cured film) to the flexible circuit board substrate. The purpose of temporary bonding is to ensure that the cover film or pure adhesive film can be firmly bonded to the flexible circuit board substrate during subsequent fast pressing and curing processes, preventing displacement or detachment before the next pressing process.

[0279] 2) The thermally conductive protection part is made of liquid adhesive and is covered to the window of the main body protection part by screen printing;

[0280] Printing accuracy ≤±0.2mm Curing conditions Temperature 120–180℃, 60–120 min

[0281] Screen printing, a type of stencil printing, uses a screen as a printing plate and employs a photosensitive method to create a screen printing plate with images and text. During the printing process, ink is transferred to the substrate through the mesh openings of the image area by a squeegee, forming an image and text identical to the original artwork. Therefore, a protective layer material containing thermally conductive particles can be printed onto the windows of the protective section of the main body using a screen printing stencil.

[0282] 3) The thermally conductive protection part is applied by spraying liquid adhesive onto the window of the main body protection part;

[0283] Spraying precision ≤±0.2mm Thickness uniformity ±10％

[0284] 7. Immersion Gold: Immersion gold treatment is performed on the surface of the flexible circuit board after copper plating. Metal ions are reduced to elemental metals through chemical deposition and deposited on the copper layer. This can improve the conductivity, corrosion resistance and wear resistance of the flexible circuit board.

[0285] 8. Surface Mount Technology (SMT): Precisely mount electronic components onto flexible circuit boards.

[0286] The above text provides a detailed description of the flexible circuit board 4. The following text will elaborate on the specific application of the flexible circuit board 4 in the heat dissipation of the terminal device 100. It should be noted that the terminal device 100 is provided with multiple flexible circuit boards 4, of which at least some flexible circuit boards 4 adopt the flexible circuit board 4 provided in the embodiments of this application described above. Therefore, the flexible circuit board 4 with the thermally conductive protection part 432 will be referred to as the thermally conductive flexible circuit board 403 in the following text.

[0287] Understandably, the flexible circuit board 4 can be used in both non-foldable and foldable terminal devices.

[0288] Please see Figures 14a-16 , Figure 14a This is a schematic diagram showing the positional relationship of the thermally conductive flexible circuit board in the first embodiment of the terminal device of this application. Figure 14b This is a schematic diagram of the heat dissipation path of the thermally conductive flexible circuit board in the first embodiment of the terminal device of this application. Figure 15 This is a cross-sectional schematic diagram of the thermally conductive flexible circuit board in the first embodiment of the terminal device of this application. Figure 16 This is a top view of the thermally conductive flexible circuit board in the first embodiment of the terminal device of this application.

[0289] It is understandable that, such as Figure 4a As shown, the top area 101 where the main circuit board 141 is located and the battery compartment area 102 where the battery 13 is located in the terminal device 100 will generate more heat, while the bottom area 103 where the sub-circuit board 142 is located and the housing 1 are areas with lower temperatures, so the heat can be conducted to the bottom area 103 and the housing 1.

[0290] like Figure 14a and Figure 16 As shown, in one possible implementation, at least one thermally conductive flexible circuit board 403 is electrically connected to a main circuit board 141 at one end along its length direction x, and electrically connected to a sub-circuit board 142 at the other end. The thermally conductive flexible circuit board 403 has a first bendable area 4331, a thermally conductive area 434, and a second bendable area 4332 arranged sequentially along its length direction x. The thermally conductive protection portion 432 of the thermally conductive area 434 along its thickness direction z contacts the battery 13, and the other thermally conductive area 434 contacts the middle frame 11 of the housing 1. The first bendable area 4331 extends from the top region 101 to the battery compartment region 102, and the second bendable area 4332 extends from the battery compartment region 102 to the bottom region 103.

[0291] In this design, a portion of the thermally conductive flexible circuit board 403 has a thermally conductive protection section 432 that contacts the battery 13, while another portion of the thermally conductive protection section 432 is used to conduct heat out of the flexible circuit board 4. In other words, the thermally conductive flexible circuit board 403 can be inserted between the battery 13 and the middle frame 11, and a thermally conductive protection section 432 is provided in the area where the battery 13 and the middle frame 11 are positioned opposite each other, forming a thermally conductive area 434. This allows for the rapid conduction of the large amount of heat generated during the charging and discharging process of the battery 13, thereby helping to improve the charging rate of the battery 13, enhance the heat dissipation capacity of the terminal device 100, and ensure the safety and reliability of the terminal device 100.

[0292] In one example, such as Figure 14b and Figure 15 As shown, the thermally conductive protection portion 432 on one side of the thermally conductive area 434 along its thickness direction z contacts the battery 13, and the thermally conductive protection portion 432 on the other side contacts the middle frame 11 of the housing 1. The large amount of heat generated by the battery 13 is quickly conducted through the thermally conductive protection portion 432 of the flexible circuit board 4 and the middle frame 11, achieving heat dissipation. In another example, the thermally conductive protection portion 432 on one side of the thermally conductive area 434 along its thickness direction z contacts the battery 13, and the thermally conductive protection portion 432 on the other side contacts the back cover of the housing. This embodiment of the application does not limit this.

[0293] It should be noted that the size of the thermal protection part 432 is not limited. For example... Figure 14b As shown, the battery 13 has a core heat-generating area 134. In one possible implementation, a portion of the thermally conductive protective part 432 of at least one thermally conductive flexible circuit board 403 contacts the core heat-generating area 134 of the battery 13, and a portion of the thermally conductive protective part 432 contacts the housing 1, for dissipating heat from inside the flexible circuit board 4 through the housing 1. That is, the thermally conductive protective part 432 is disposed on two opposite sides in its thickness direction z, and is specifically designed for the core heat-generating area 134 of the battery 13, so that a large amount of heat generated by the battery 13 can be directly conducted to the housing 1 through the thermally conductive flexible circuit board 403, greatly improving the overall heat dissipation efficiency of the terminal device 100. In one example, in the length direction x of the terminal device 100, the core heat-generating area 134 includes the central region 1341 of the battery cell inside the battery, and a portion of the thermally conductive protective part 432 of at least one thermally conductive flexible circuit board 403 contacts the central region 1341 of the battery cell.

[0294] The core heat-generating area of ​​a battery refers to the region where the temperature rises during the charging and discharging process due to factors such as electrochemical reactions and current flow. In mobile phone batteries, the core heat-generating area is typically located in the central region 1341 of the battery cell, as well as around the tabs and battery protection board.

[0295] Understandably, under the condition of controlling the battery temperature at a certain level, the battery that directly contacts the thermal protection part 432 on the thermally conductive flexible circuit board 403 to dissipate heat will have a shorter time required to reach full charge, i.e., the charging rate will be improved. This is because the thermal protection part 432 of the thermally conductive flexible circuit board 403 can increase the heat dissipation path of the battery 13 in the terminal device 100, improve the heat dissipation efficiency of the battery 13, and thus improve the performance of the battery 13.

[0296] Furthermore, in one possible implementation, such as Figure 14a and Figure 16 As shown, the thermally conductive flexible circuit board 403 also has another thermally conductive area 434, which is located outside the end of the second bendable area 4332 away from the thermally conductive area 434 in the length direction x of the thermally conductive flexible circuit board 403. The other thermally conductive area 434 is located in the bottom region 103 of the housing.

[0297] Furthermore, in one possible implementation, such as Figure 15 and Figure 16 As shown, the thermally conductive flexible circuit board 403 includes an additional heat dissipation structure 63, which extends to the outer periphery of the thermally conductive protection portion 432. The additional heat dissipation structure 63 can contact the thermally conductive protection portion 432 of another thermally conductive area 434, and has a larger contact area with the lower-temperature region, which is beneficial to improving the heat dissipation performance of the thermally conductive flexible circuit board 403. Specifically, the additional heat dissipation structure 63 can be any of the heat dissipation structures 62 mentioned above, which will not be further described in this embodiment.

[0298] Simply put, such as Figure 14a and Figure 14bAs shown, the heat generated by the main circuit board 141 can be conducted into the thermally conductive flexible circuit board 403 through the board-to-board connector 16, and along its traces at the corresponding thermally conductive area 434 in the battery compartment area 102, part of it is conducted to the housing 1 for heat dissipation, and part of it is conducted to the bottom area 103, that is, conducted to the lower-temperature sub-circuit board 142 through the board-to-board connector 16 for heat dissipation; while part of the heat generated by the battery can be directly conducted to the housing 1 through the thermally conductive area 434 for heat dissipation, and part of it can be conducted to the bottom area 103, that is, conducted to the lower-temperature sub-circuit board 142 through the board-to-board connector 16 for heat dissipation. Meanwhile, in order to improve the efficiency of heat conduction, a portion of the thermally conductive flexible circuit board 403 located outside the end of the second bendable area 4332 away from the heat conduction area 434 in the x-direction of the length direction can also be provided with a thermally conductive protection part 432 to form another heat conduction area 434, thereby increasing the heat dissipation area. In this way, the thermally conductive flexible circuit board 403 can conduct a large amount of heat generated by the main circuit board 141 to the housing 1 and the sub-circuit board 142, as well as conduct a large amount of heat generated by the battery 13 to the housing 1 and the sub-circuit board 142, thereby increasing the heat dissipation path and heat dissipation space in the terminal device 100 and greatly improving the overall heat dissipation efficiency of the terminal device 100.

[0299] It should be noted that in other possible implementations, a portion of the thermally conductive flexible circuit board 403, the thermally conductive protection part 432, can also directly participate in the conduction of heat generated by the main circuit board 141. That is, a thermally conductive protection part 432 can also be provided at the end of the first bendable area 4331 away from the thermally conductive area 434 in the length direction x of the thermally conductive flexible circuit board 403, so that the heat generated by the main circuit board 141 can be quickly introduced into the thermally conductive flexible circuit board 403 to achieve heat dissipation.

[0300] Furthermore, such as Figure 14a and Figure 14b As shown, at least one heat dissipation structure 62 in the terminal device 100 includes a first heat dissipation structure 621 that contacts at least one heat-generating device 61 (e.g., SOC) of the heat source 6. That is, a portion of the thermally conductive protective part 432 of at least one thermally conductive flexible circuit board 403 contacts the first heat dissipation structure 621. Alternatively, a portion of the thermally conductive protective part 432 of the thermally conductive flexible circuit board 403 may simultaneously contact the main circuit board 141 and the first heat dissipation structure 621 to achieve heat dissipation.

[0301] In summary, the thermally conductive flexible circuit board 403 can conduct a large amount of heat generated by the main circuit board 141 and the heat-generating devices 61 mounted on the main circuit board 141 (e.g., system-on-a-chip, image processor, etc.) to areas with lower temperatures (e.g., the housing 1 and the secondary circuit board 142). This prevents the local temperature in the area where the main circuit board 141 is located from becoming too high and affecting the reliability of the heat-generating devices 61 in that area. Thus, within a limited space, the system heat dissipation efficiency of the terminal device 100 is greatly improved, which helps the terminal device 100 achieve higher intelligence, higher computing power, higher functional integration, and overall miniaturization. In addition, the thermally conductive flexible circuit board 403 can contact more areas with higher temperatures. It can directly contact the main circuit board 141 or conduct heat through the heat dissipation structure 62, increasing the heat dissipation pathways within the terminal device 100 and improving the overall heat dissipation efficiency of the terminal device 100.

[0302] The foregoing is an exemplary description of the heat dissipation application of the thermally conductive flexible circuit board 403 in a non-foldable terminal device. Those skilled in the art will understand that the structure mentioned above, which utilizes the flexible circuit board 4 with thermally conductive protection 432 to conduct heat to the battery 13, the main circuit board 141, and the heat-generating device 61 on the main circuit board 141, is also applicable to the foldable terminal device 200. The foldable terminal device 200 can be folded only once, or twice (i.e., a three-fold terminal device), or folded more than once; this application does not limit this. The following will describe the heat dissipation application of the flexible circuit board in a foldable terminal device.

[0303] First, with reference to the accompanying drawings, the second embodiment will be described using the terminal device 100 as a foldable terminal device 200 that can be folded once.

[0304] Please see Figures 17a-17c , Figure 17a This is a three-dimensional structural diagram of the second embodiment of the terminal device in the unfolded state according to the present application. Figure 17b This is a three-dimensional structural diagram of the second embodiment of the terminal device according to the present application in a folded state. Figure 17c This is a schematic diagram of the rear structure of the terminal device according to a second embodiment of this application (the back cover has been removed). It should be noted that the accompanying drawings of this application embodiment are for illustrative purposes only, and the size and positional relationship of the components in the drawings do not represent the size and positional relationship of the components in the actual product. The foldable terminal device may also include more or fewer components than shown in the drawings, and this application embodiment does not impose any limitations on this.

[0305] like Figures 17a-17cAs shown, in one possible implementation, the terminal device 100 is a foldable terminal device 200, for example, a foldable mobile phone. The foldable terminal device 200 can be folded and unfolded to switch forms in different usage scenarios. It should be noted that the foldable terminal device 200 can be a vertically foldable terminal device 200 or a horizontally foldable terminal device 200, and this application embodiment does not limit this.

[0306] In one possible implementation, such as Figures 17a-17c As shown, the foldable terminal device 200 includes multiple housings 1 and a display screen 15 laid on the multiple housings 1. The multiple housings 1 include a first housing 21 and a second housing 22. Two adjacent housings 1 are rotatably connected by a pivot mechanism 3, that is, the first housing 21 and the second housing 22 are rotatably connected by the pivot mechanism 3, so that the foldable terminal device 200 can switch between a folded state and an unfolded state.

[0307] It should be noted that there may be one or more rotating shaft mechanisms 3, and this application embodiment does not limit this.

[0308] In one possible implementation, such as Figure 17a As shown, the display screen 15 includes a first part 151, a second part 152, and a foldable part 153. The first part 151 is fixedly connected to the first housing 21, the second part 152 is fixedly connected to the second housing 22, and the foldable part 153 is located between the first part 151 and the second part 152, and is stacked with the pivot mechanism 3. During use, the first part 151 and the second part 152 remain in a flat state, while the foldable part 153 can be bent to change the angle between the first part 151 and the second part 152, so that the display screen 15 folds or unfolds with the movement of the housing. For example, the foldable part 153 can be made of a flexible material to make it bendable.

[0309] like Figure 17c As shown, in one possible implementation, the first housing 21 houses the main circuit board 141 and the first battery 131, while the second housing 22 houses the sub-circuit board 142 and the second battery 132. It should be noted that the number of circuit boards and batteries in the foldable terminal device 200 is not limited. In other possible implementations, the foldable terminal device 200 may also have only one battery, that is, powering all the electronic components within the housing with a single battery.

[0310] In one possible implementation, such as Figure 17cAs shown, the secondary circuit board 142 is electrically connected to the main circuit board 141 via the flexible circuit board 4. In other words, the flexible circuit board 4 passes through the pivot mechanism 3, thereby ensuring the communication and electrical connections between electronic components in different housings of the foldable terminal device 200.

[0311] It should be noted that at least one flexible circuit board 4 in the foldable terminal device 200 that can be folded once adopts the thermally conductive flexible circuit board 403 with thermally conductive protection part 432 provided in the embodiments of this application. The specific arrangement of the thermally conductive flexible circuit board 403 in the area where the battery 13 is located can be referred to the application of the thermally conductive flexible circuit board 403 in the non-foldable terminal device above. The specific application of the thermally conductive flexible circuit board 403 at the pivot mechanism 3 in the foldable terminal device 200 will be uniformly explained in the following text in conjunction with the accompanying drawings.

[0312] The following description, in conjunction with the accompanying drawings, will use a three-fold foldable terminal device 200 as an example of a third embodiment for illustrative purposes.

[0313] Please see Figure 18a and Figure 18b , Figure 18a This is a three-dimensional structural diagram of the terminal device in the folded state according to the third embodiment of this application. Figure 18b This is a schematic diagram of the rear structure of the terminal device according to a third embodiment of this application (the back cover has been removed). It should be noted that the accompanying drawings of this application embodiment are for illustrative purposes only, and the size and positional relationship of the components in the drawings do not represent the size and positional relationship of the components in the actual product. The terminal device may also include more or fewer components than shown in the drawings, and this application embodiment does not impose any limitations on this.

[0314] like Figure 18a and Figure 18b As shown, the foldable terminal device 200 comprises multiple housings, including a first housing 21, a second housing 22, and a third housing 23. The pivot mechanism 3 includes a first pivot mechanism 31 and a second pivot mechanism 32. The first housing 21 and the second housing 22 are rotatably connected via the first pivot mechanism 31, and the second housing 22 and the third housing 23 are rotatably connected via the second pivot mechanism 32, allowing the foldable terminal device 200 to switch between a folded state and an unfolded state. In one possible implementation, such as... Figure 18a As shown, the first rotating shaft mechanism 31 is an inward folding mechanism, and the second rotating shaft mechanism 32 is an outward folding mechanism. In other possible implementations, the first rotating shaft mechanism 31 can also be an outward folding mechanism, and the second rotating shaft mechanism 32 can also be an inward folding mechanism, etc., and this application embodiment does not limit this. Those skilled in the art will understand that the rotating shaft mechanism 3 is used to rotatably connect the two housings connected to it, and the specific structure of each rotating shaft mechanism 3 is not limited in this application embodiment.

[0315] In one possible implementation, a main circuit board 141 and a first battery 131 are disposed in the first housing 21, a secondary circuit board 142 and a second battery 132 are disposed in the second housing 22, and a secondary circuit board 142 and a third battery 133 are disposed in the third housing 23.

[0316] It should be noted that the number of circuit boards and batteries in the foldable terminal device 200 is not limited. In other alternative embodiments, only one battery may be provided to power all electronic components within the housing. Alternatively, two batteries may be provided, for example, the second housing 22 and the third housing 23 may share one battery. Four, five, or more batteries may also be provided, for example, multiple batteries may be provided within the same housing. Similarly, the foldable terminal device 200 may also have only one circuit board, for example, only a main circuit board 141, with wiring connecting the electronic components within the second housing 22 and the third housing 23 to the main circuit board 141. Alternatively, the foldable terminal device 200 may also have two, three, four, or five circuit boards, for example, multiple circuit boards may be provided within the same housing; these will not be listed individually in this application.

[0317] In one possible implementation, such as Figure 8b As shown, the secondary circuit board 142 is electrically connected to the main circuit board 141 via a flexible circuit board 4. The flexible circuit board 4 passes through the first pivot mechanism 31, and another flexible circuit board 4 passes through the first pivot mechanism 31, the second housing 22, and the second pivot mechanism 32. Therefore, both flexible circuit boards 4 are through-axis flexible circuit boards. As the foldable terminal device 200 opens and closes, the through-axis flexible circuit boards also bend or extend to adapt to the shape of the device.

[0318] It should be noted that the foldable terminal device 200 integrates high-performance electronic components. A heat dissipation structure 62 can be used to specifically dissipate the large amount of heat generated by the heat source 6 within the foldable terminal device 200. One possible implementation is as follows: Figure 17c As shown, a heat dissipation structure 62 can be provided for the area where the SOC1412 is located and the area where the battery (e.g., the first battery 131) is located, which can quickly conduct heat to the area with a lower temperature (e.g., the bottom area of ​​the first housing).

[0319] It should be noted that at least one flexible circuit board 4 in the foldable terminal device 200 that folds twice adopts the thermally conductive flexible circuit board 403 with a thermally conductive protection part 432 provided in the embodiments of this application. The specific arrangement of the thermally conductive flexible circuit board 403 in the area where the battery is located can be found in the application of the thermally conductive flexible circuit board 403 in non-foldable terminal devices described above, and will not be repeated in this embodiment. The following will describe the specific application of the thermally conductive flexible circuit board 403 at the hinge mechanism 3 in the foldable terminal device 200.

[0320] Please see Figures 19a-20d , Figure 19a This is a simplified structural diagram of the thermally conductive flexible circuit board layout in the second embodiment of the terminal device according to this application. Figure 19b This is a simplified structural diagram of the thermally conductive flexible circuit board layout in the second embodiment of the terminal device of this application. Figure 20a This is a partial cross-sectional schematic diagram of the thermally conductive flexible circuit board in the second embodiment of the terminal device of this application. Figure 20b This is a second partial cross-sectional schematic diagram of the thermally conductive flexible circuit board in the second embodiment of the terminal device of this application. Figure 20c This is a schematic cross-sectional view of another possible structure of the thermally conductive flexible circuit board in the second embodiment of the terminal device of this application. Figure 20d This is a second possible cross-sectional view of the thermally conductive flexible circuit board in the second embodiment of the terminal device of this application.

[0321] It is understandable that, such as Figures 19a-20d As shown, and in combination Figure 17cIt is understood that at least one thermally conductive flexible circuit board 403 passes through the pivot mechanism 3 between the first housing 21 and the second housing 22. In one possible implementation, one end of the thermally conductive flexible circuit board 403 passing through the pivot mechanism 3 is electrically connected to the main circuit board 141, and the other end is electrically connected to the sub-circuit board 142 in the second housing 22. Furthermore, a portion of the thermally conductive flexible circuit board 403 with thermal protection 432 is located in the first housing 21 and in contact with the main circuit board 141, while a portion of the thermally conductive protection 432 is located in the second housing 22, for dissipating heat from inside the thermally conductive flexible circuit board 403. In this way, the main circuit board 141 and the heat-generating device 61 on the main circuit board 141 are located in the first housing 21, resulting in higher heat levels in the first housing 21 and relatively lower temperatures in the other housings (second housing 22). Therefore, by utilizing the thermal conductivity and bending performance of the thermally conductive flexible circuit board 403, the area passing through the pivot mechanism 3 in the thermally conductive flexible circuit board 403 can be designated as a bendable area 433, enabling it to maintain high bending performance under long-term dynamic bending conditions. Multiple thermally conductive areas 434 are also positioned at specific locations. The thermal protection parts 432 of some thermally conductive areas 434 are in contact with the main circuit board 141 in the first housing 21, while the thermal protection parts 432 of some thermally conductive areas 434 are located in the second housing 22. Combined with the lines in the conductive layer 42 of the bendable area 433, a thermally conductive path is formed across the bendable area 433. This allows heat from the higher-temperature first housing 21 to be conducted to the lower-temperature second housing 22 through the thermally conductive flexible circuit board 403, preventing excessive heat in the area where the main circuit board 141 is located in the first housing 21 from affecting its performance. This improves the system heat dissipation performance of the foldable terminal device 200 and increases its reliability.

[0322] In other possible implementations, such as Figures 19a-20d As shown, and in combination Figure 18bIt is understood that a portion of the thermally conductive protective portion 432 of the thermally conductive flexible circuit board 403 passing through the rotating shaft mechanism 3 is located in the first housing 21 and in contact with the first heat dissipation structure (not shown in the figure). Another portion of the thermally conductive protective portion 432 is located in another housing (third housing 23) between the first housing 21 and the second housing 22, for dissipating heat from inside the thermally conductive flexible circuit board 403. Alternatively, a portion of the thermally conductive protective portion 432 of the thermally conductive flexible circuit board 403 passing through the rotating shaft mechanism 3 is located in the first housing 21 and in contact with the main circuit board 141 and the first heat dissipation structure. A portion of the thermally conductive protective portion 432 is located in the second housing 22 and another housing (third housing 23) between the first housing 21 and the second housing 22, for dissipating heat from inside the thermally conductive flexible circuit board 403. Those skilled in the art will understand that the embodiments of this application do not limit the specific orientation and structure of the thermally conductive flexible circuit board 403. The partitioning of the thermally conductive protective portion 432 and the main body protection portion 431 in the thermally conductive flexible circuit board 403 can be reasonably arranged according to the heat conduction requirements and the position of the rotating shaft mechanism 3.

[0323] It should be noted that the portion of the thermally conductive flexible circuit board 403 passing through the rotating shaft mechanism 3 within the first housing 21, which has a higher temperature, may or may not have a thermally conductive protection part 432. This application embodiment does not impose any restrictions on this.

[0324] It should be noted that the thermally conductive flexible circuit board 403 passing through the rotating shaft mechanism 3 may or may not be in contact with the first heat dissipation structure. This application embodiment does not impose any restrictions on this, and those skilled in the art can make reasonable settings according to their needs.

[0325] like Figure 19b As shown, in one possible implementation, at least a portion of the outer surface of the thermally conductive protection portion 432 is covered with an additional heat dissipation structure 63, which extends to the outer periphery of the thermally conductive protection portion 432. That is, the additional heat dissipation structure 63 can be provided on the sub-shell (which can be understood as the second shell 22, or another shell located between the first shell 21 and the second shell 22, i.e., the third shell 23). In this way, when most of the heat in the first shell 21 is conducted to the sub-shell for heat dissipation, the thermally conductive protection portion 432 of the sub-shell can also contact the heat source 6 through the additional heat dissipation structure 63, increasing the contact area. The heat dissipated by the thermally conductive protection portion 432 is then transferred to a wider, lower-temperature area through the additional heat dissipation structure 63, which helps improve the heat dissipation efficiency of the thermally conductive flexible circuit board 403, thereby improving the overall heat dissipation capacity.

[0326] It should be noted that the specific structure of the thermally conductive flexible circuit board 403 passing through the rotating shaft mechanism 3 is not limited. In one possible implementation, such as... Figure 20aAs shown, the thermally conductive flexible circuit board 403 achieves electrical connection between circuit boards of different housings through a board-to-board connector 16. The thermally conductive flexible circuit board 403 includes two conductive layers 42, one of which is a protective layer 43 comprising multiple thermally conductive protection sections 432. Specifically, the area where the thermally conductive protection sections 432 are located is the thermally conductive area 434, and the other areas are the bendable areas 433. It can be understood that the hinge mechanism 3 is located in the area where the bendable area 433 is located, thereby realizing the folding function of the foldable terminal device 200. The thermally conductive areas 434 are located on both sides of the hinge mechanism 3, thereby realizing heat conduction across the axis of the foldable terminal device 200 and improving the overall heat dissipation efficiency.

[0327] In another possible implementation, such as Figure 20c As shown, the thermally conductive flexible circuit board 403 includes two conductive layers 42, wherein each of the two protective layers 43 disposed opposite to each other in the thickness direction z includes multiple thermally conductive protective parts 432, so that the thermally conductive flexible circuit board 403 can contact more heat sources or areas with lower temperatures, thereby improving the heat dissipation efficiency of the device.

[0328] It should be noted that, as Figure 20a As shown, in one example, all thermally conductive protection parts 432 may be disposed on the same side of the thermally conductive flexible circuit board 403 in the thickness direction with the board-to-board connector 16, and some of the thermally conductive protection parts 432 may be in contact with the main circuit board. In another example, some of the thermally conductive protection parts 432 may be disposed on the same side of the thermally conductive flexible circuit board 403 with the board-to-board connector 16, while other portions of the thermally conductive protection parts 432 and the board-to-board connector 16 may be disposed on different sides of the thermally conductive flexible circuit board 403.

[0329] In yet another example, such as Figure 20c As shown, and in combination Figure 17c It is understood that all thermally conductive protection parts 432 can be disposed on different sides of the thermally conductive flexible circuit board 403 in the thickness direction z with the board-to-board connector 16. At this time, the thermally conductive flexible circuit board 403 is electrically connected on one side of the thickness direction z through the board-to-board connector 16, so that the heat on the main circuit board 141 can be conducted into the thermally conductive flexible circuit board 403, and the thermally conductive flexible circuit board 403 is provided with a thermally conductive protection part on the other side of the thickness direction z, which can contact the heat source or the heat dissipation structure 62 (the heat dissipation structure 62 is in contact with the heat-generating device of the heat source, which can be a SOC). It can conduct some of the heat through the thermally conductive flexible circuit board 403 to a lower temperature area (e.g., the second housing 22) to achieve heat dissipation, or add an additional heat dissipation structure to further improve the heat dissipation efficiency. This application embodiment does not limit this.

[0330] In other possible implementations, the thermally conductive flexible circuit board 403 achieves electrical connection between circuit boards in different housings via a board-to-board connector 16, and the thermally conductive flexible circuit board 403 includes three conductive layers 42. Specifically, in the two protective layers 43 disposed opposite each other in the thickness direction z of the thermally conductive flexible circuit board 403, such as... Figure 20b and Figure 20d As shown, the thermal protection part 432 can be provided on one layer or on both layers. This application embodiment does not limit this.

[0331] Furthermore, the number of thermally conductive flexible circuit boards 403 passing through the rotating shaft mechanism 3 is unlimited. In one possible implementation, one thermally conductive flexible circuit board 403 including two conductive layers 42 and another thermally conductive flexible circuit board 403 including two conductive layers 42 can be provided on the same rotating shaft mechanism 3. This application embodiment does not limit this.

[0332] When the thermal conductivity of the thermal protection part 432 is constant, the heat dissipation of the foldable terminal device 200 is achieved by the thermally conductive flexible circuit board 403 passing through the pivot mechanism 3. Through measurement, it was found that the temperature of the display screen, the hot spot A on the back cover, and the hot spot B on the back cover in the foldable terminal device 200 decreased. In one example, the temperature of the display screen decreased by 0.05℃, the temperature of the hot spot A on the back cover decreased by 0.09℃, and the temperature of the hot spot B on the back cover decreased by 0.07℃. The heat dissipation capacity was improved in all places. Therefore, the thermally conductive flexible circuit board 403 can improve the heat dissipation efficiency of the foldable terminal device 200.

[0333] It should be noted that the back cover hotspot A and back cover hotspot B are the main detection points in the foldable terminal device 200, which ensures the reliability of the foldable terminal device 200 when it is affected by a lot of heat during operation. Generally speaking, back cover hotspot A refers to the area where the CCM is located, and back cover hotspot B refers to the area where the SOC is located.

[0334] Furthermore, an additional heat dissipation structure 63 is added in areas with lower temperatures (such as the area where the secondary circuit board 142 is located in the second housing 22). The heat dissipation of the foldable terminal device 200 is achieved by using the thermally conductive flexible circuit board 403 passing through the pivot mechanism 3. The temperatures at the display screen, back cover hotspot A, and back cover hotspot B in the foldable terminal device 200 can be reduced by 0.1℃, 0.15℃, and 0.12℃, respectively. Its heat dissipation capacity is also improved at the display screen, back cover hotspot A, and back cover hotspot B.

[0335] Furthermore, comparing the temperatures before and after adding the additional heat dissipation structure 63, it can be seen that the heat dissipation efficiency of the foldable terminal device 200 can be improved by using the thermally conductive flexible circuit board 403 passing through the pivot mechanism 3, and the heat dissipation efficiency of the foldable terminal device 200 can be further improved by setting the additional heat dissipation structure 63 in the area with lower temperature.

[0336] Obviously, those skilled in the art can make various modifications and variations to the embodiments of this application without departing from the scope of the embodiments of this application. Therefore, if these modifications and variations to the embodiments of this application fall within the scope of the claims of the embodiments of this application and their equivalents, then the embodiments of this application are also intended to include these modifications and variations.

Claims

1. A flexible circuit board for terminal devices, comprising at least one substrate layer, characterized in that, The flexible circuit board further includes a conductive layer and a protective layer. The conductive layer is disposed on one side of the substrate layer along its thickness direction, and the protective layer covers and contacts the conductive layer. Alternatively, the flexible circuit board further includes at least two conductive layers and two protective layers. The conductive layer is disposed on one or both sides of the substrate layer along its thickness direction, and the two protective layers respectively cover and contact the uppermost and lowermost conductive layers of the at least two conductive layers. Wherein, the protective layer or at least one of the two protective layers includes a body protection part and at least one thermally conductive protection part, wherein the body protection part and the at least one thermally conductive protection part both cover and contact the corresponding conductive layer; Furthermore, each of the thermally conductive protection portions has thermal conductivity and electrical insulation properties, and at least a portion of the thermally conductive protection portions of the flexible circuit board is used for thermal coupling with the heat source of the terminal device, so that the heat generated by the heat source can be conducted through the thermally conductive protection portion to the conductive layer it covers and contacts.

2. The flexible circuit board as described in claim 1, characterized in that, The thermally conductive protection part includes a cover layer that covers the conductive layer corresponding to the contact, and electrically insulating thermally conductive particles are added to the cover layer.

3. The flexible circuit board as described in claim 2, characterized in that, The heat-conducting particles are inorganic non-metallic heat-conducting particles.

4. The flexible circuit board as described in claim 3, characterized in that, The thermally conductive particles are made of at least one of boron nitride, aluminum nitride, and aluminum oxide.

5. The flexible circuit board as described in any one of claims 2-4, characterized in that, The covering layer contains thermally conductive particles of various shapes.

6. The flexible circuit board according to any one of claims 2-5, characterized in that, The covering layer is an adhesive layer with added thermally conductive particles, and the adhesive layer is made of an adhesive. Alternatively, the covering layer includes an adhesive layer and a cover film stacked along its thickness direction, the adhesive layer covering the corresponding conductive layer, the cover film covering the side of the adhesive layer away from the corresponding conductive layer, the thermally conductive particles added to both the adhesive layer and the cover film, the adhesive layer being made of an adhesive, and the cover film being made of a resin material.

7. The flexible circuit board as described in claim 6, characterized in that, The resin material includes at least one of the following: polyimide, epoxy resin, acrylic acid, polyester resin, polyurethane resin, polyvinylidene chloride, polydimethylsiloxane, polystyrene, low-density polyethylene, high-density polyethylene, polypropylene, polyetheretherketone, and polyvinyl chloride.

8. The flexible circuit board according to any one of claims 1-7, characterized in that, In the protective layer, the main body protection part is provided with a window at the position corresponding to each of the thermally conductive protection parts, and the thermally conductive protection part is embedded in the corresponding window and connected to the main body protection part.

9. The flexible circuit board according to any one of claims 1-8, characterized in that, In the protective layer, the thickness of each of the thermally conductive protective parts is equal to the thickness of the main protective part.

10. The flexible circuit board according to any one of claims 1-9, characterized in that, The protective layer includes a plurality of thermally conductive protective portions spaced apart along the length of the flexible circuit board.

11. The flexible circuit board according to any one of claims 1-10, characterized in that, Each of the two protective layers includes the main body protection part and at least one of the thermally conductive protection parts.

12. The flexible circuit board as described in claim 11, characterized in that, The orthographic projection of all the thermally conductive protective elements in one of the two protective layers onto the other protective layer overlaps with at least a portion of the thermally conductive protective elements in the other protective layer.

13. The flexible circuit board according to any one of claims 1-12, characterized in that, One portion of the thermally conductive protection part of the flexible circuit board is used for thermal coupling with the heat source of the terminal device, and another portion of the thermally conductive protection part is used to conduct heat out of the flexible circuit board, so that the heat generated by the heat source can be conducted through one portion of the thermally conductive protection part to the conductive layer it covers and contacts, and then through the conductive layer to the other portion of the thermally conductive protection part and finally conducted out of the flexible circuit board.

14. The flexible circuit board as described in claim 13, characterized in that, At least a portion of the outer surface of the other thermally conductive protection portion is covered with an additional heat dissipation structure, which extends to the outer periphery of the thermally conductive protection portion.

15. The flexible circuit board according to any one of claims 1-14, characterized in that, At least one thermally conductive structure is provided between the conductive layers of different layers to achieve heat conduction between the conductive layers of different layers through the thermally conductive structure, wherein the flexible circuit board has a via for the corresponding thermally conductive structure to pass through at the position of each thermally conductive structure.

16. The flexible circuit board as described in claim 15, characterized in that, The heat-conducting structure is configured as: an integral heat-conducting column, which can be solid or hollow. Alternatively, the heat-conducting structure can be configured as a split structure, including conductive pillars and heat-conducting pillars, so that the heat-conducting structure is conductive. The conductive pillars are hollow, and the outer surface of the conductive pillars is in contact with the wall of the corresponding via and the corresponding conductive layer. The heat-conducting pillars pass through the hollow part of the conductive pillars and are solid or hollow, and the heat-conducting pillars are in contact with the inner surface of the conductive pillars, or the heat-conducting pillars are in contact with the inner surface of the conductive pillars and the corresponding conductive layer. The heat-conducting column is either electrically conductive or electrically insulating.

17. The flexible circuit board as described in claim 16, characterized in that, The heat-conducting pillar is made of copper, tin, thermally conductive adhesive, or thermally conductive resin.

18. The flexible circuit board according to any one of claims 15-17, characterized in that, Each of the conductive layers includes at least one signal transmission line. The conductive layers of different layers have signal transmission lines that transmit the same signal and overlap in at least a portion of their regions. A conductive heat-conducting structure is provided between the overlapping regions of the signal transmission lines that transmit the same signal in the conductive layers of different layers.

19. The flexible circuit board according to any one of claims 1-18, characterized in that, The thermal conductivity of the thermally conductive protection part is greater than or equal to 1.5 W / m·K; The body protection part includes a cover layer that covers the conductive layer corresponding to the contact. No thermally conductive particles are added to the cover layer, and the body protection part is configured as an electrically insulating, bendable protective structure. The flexible circuit board has at least one thermally conductive area and at least one bendable area arranged along its length direction. The thermally conductive area is the region where the thermally conductive protection portion of the flexible circuit board is located along its length direction. The bendable area is the region where the main body protection portion of the flexible circuit board is located along its length direction. All regions of each protective layer in the bendable area are the main body protection portion.

20. A terminal device, comprising a housing and a plurality of electronic units mounted on the housing, further comprising at least one flexible circuit board, wherein different electronic units are electrically connected through the flexible circuit board, characterized in that, At least a portion of the flexible circuit board is a flexible circuit board as described in any one of claims 1-19, and the flexible circuit board having the thermally conductive protection portion is a thermally conductive flexible circuit board; The terminal device further includes a heat source, and at least a portion of the thermally conductive protective portion of each of the thermally conductive flexible circuit boards is thermally coupled to the heat source.

21. The terminal device as described in claim 20, characterized in that, The terminal device further includes at least one heat dissipation structure in contact with the heat source; the thermally conductive protective part of the thermally conductive flexible circuit board is in contact with the heat source or the heat dissipation structure.

22. The terminal device as described in claim 21, characterized in that, A thermal interface material layer is filled between the thermally conductive protection part and the heat source or the heat dissipation structure, so that the thermally conductive protection part can contact the heat source or the heat dissipation structure through the thermal interface material layer. The thermal interface material layer is made of thermally conductive silicone grease, thermally conductive gel, or thermally conductive tape.

23. The terminal device according to any one of claims 20-22, characterized in that, The heat source includes a battery, which is mounted on the housing. At least one portion of the thermally conductive flexible circuit board has a thermally conductive protection section in contact with the battery, and the portion of the thermally conductive protection section is used to dissipate heat from inside the thermally conductive flexible circuit board.

24. The terminal device as described in claim 23, characterized in that, The battery has a core heat-generating area, and at least one portion of the thermally conductive flexible circuit board has a thermally conductive protection part in contact with the core heat-generating area of ​​the battery, and a portion of the thermally conductive protection part is in contact with the housing, for dissipating heat from inside the thermally conductive flexible circuit board through the housing.

25. The terminal device as described in claim 23 or 24, characterized in that, The housing has a top region, a battery compartment region, and a bottom region arranged sequentially along the length of the terminal device. The battery is installed in the battery compartment region. The terminal device also includes a main circuit board disposed in the top region and a sub-circuit board disposed in the bottom region. At least one of the thermally conductive flexible circuit boards is electrically connected to the main circuit board at one end along its length direction and electrically connected to the sub-circuit board at the other end. The thermally conductive flexible circuit board has a first bendable area, a thermally conductive area and a second bendable area arranged sequentially along its length direction. The thermally conductive protective portion on one side of the thermally conductive area along its thickness direction contacts the battery, and the thermally conductive protective portion on the other side contacts the middle plate or rear cover of the housing. The first bendable area extends from the top region to the battery compartment region, and the second bendable area extends from the battery compartment region to the bottom region. The thermally conductive flexible circuit board also has another thermally conductive area, which is located outside the end of the second bendable area away from the thermally conductive area in the length direction of the thermally conductive flexible circuit board, and the other thermally conductive area is located in the bottom region of the housing; When the thermally conductive flexible circuit board includes an additional heat dissipation structure, the additional heat dissipation structure contacts the thermally conductive protection portion of the other thermally conductive area.

26. The terminal device according to any one of claims 20-25, characterized in that, The heat source includes a main circuit board and at least one heating device mounted on the main circuit board; When the terminal device includes at least one heat dissipation structure in contact with the heat source, the at least one heat dissipation structure includes a first heat dissipation structure in contact with the at least one heat-generating device of the heat source; In this embodiment, at least one portion of the thermally conductive flexible circuit board has a thermally conductive protection part in contact with the main circuit board and / or the first heat dissipation structure, and the portion of the thermally conductive protection part is used to dissipate heat from inside the thermally conductive flexible circuit board.

27. The terminal device as described in claim 26, characterized in that, The terminal device is a foldable terminal device, and the housing has multiple housings, with adjacent housings being rotatably connected by a rotating shaft mechanism. The plurality of housings include a first housing and a second housing. The main circuit board is disposed in the first housing, and the second housing is provided with a sub-circuit board. At least one thermally conductive flexible circuit board passes through the pivot mechanism between the first housing and the second housing. One end of the thermally conductive flexible circuit board passing through the pivot mechanism is electrically connected to the main circuit board, and the other end is electrically connected to the sub-circuit board in the second housing. The area of ​​the thermally conductive flexible circuit board passing through the pivot mechanism is set as a bendable area. Furthermore, a portion of the thermally conductive flexible circuit board passing through the rotating shaft mechanism has its thermally conductive protection portion located in the first housing and in contact with the main circuit board and / or the first heat dissipation structure; a portion of the thermally conductive protection portion is located in the second housing; and / or other housings located between the first housing and the second housing, for dissipating heat from inside the thermally conductive flexible circuit board.

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