Composite film, rigid flexible printed circuit board, and electronic device including same

Abstract

Disclosed are a composite film, a rigid flexible printed circuit board, and an electronic device including the same. The invention relates to a composite film, a rigid flexible printed circuit board using the composite film, and an electronic device. According to an embodiment, a composite film includes: a base film layer; the first metal thin film layer is formed on one surface of the base film layer; and a second metal thin film layer formed on the opposing surfaces, in which the first metal thin film layer and the second metal thin film layer include a soft etching treated region and an oxide surface treated region, and surface roughness of the soft etching treated region and the oxide surface treated region are different from each other. Various other embodiments are possible.

Description

Technical Field

[0001] Embodiments of the present disclosure relate to composite films, rigid flexible printed circuit boards, and electronic devices including the same. Background Art

[0002] Generally, an electronic device refers to a device that performs a specific function according to a loaded program, such as a household appliance, an electronic handbook, a portable multimedia player, a mobile communication terminal, a tablet personal computer (PC), a video / audio device, a desktop / laptop computer, a vehicle navigation system, etc. For example, such an electronic device can output stored information as sound or image. As electronic devices have become highly integrated and high-speed and high-capacity wireless communications have been more widely used, various functions have been installed in a single electronic device such as a mobile communication terminal. For example, entertainment functions such as games, multimedia functions such as music / video playback, communication and security functions for mobile banking, scheduling functions and electronic wallet functions, and communication functions have been integrated into a single electronic device.

[0003] Among electronic devices, a display device provides information to a user by displaying various images on a display screen. A display device generally displays information within an assigned screen. A flexible display device including a flexible display panel that can be folded, bent, or rolled up is being developed. Unlike a rigid display device, a flexible display device can be folded, rolled up, or bent. A flexible display device that can be changed in various shapes can be carried without being limited by the existing screen size, which can improve user convenience. Summary of the invention

[0004] Technical Solution An electronic device may include a rigid flexible printed circuit board (RF PCB) that makes electrical connections to components (eg, parts or circuits).

[0005] For RFPCBs with repeated bending life in the hinge part of a flexible electronic device, an oxide surface treatment is applied uniformly (e.g., over the entire surface) to the internal copper layer surface for bonding and preventing delamination. The oxide surface treatment can enhance the bonding between the components of the RFPCB (e.g., prepreg (PPG) and laser vias in the rigid area, or a cover film in the flexible area), however, it may lead to a reduction in bending life, cracks in the notches of the surface roughness during repeated bending, and product defects. This often occurs in the hinge part of a foldable electronic device (e.g., a foldable smart phone) having a structure that undergoes repeated bending, and there is a need to improve the repeated bending life of the hinge part.

[0006] According to various embodiments, a composite film capable of improving adhesion, flex life, and bendability through heterogeneous surface treatment of a metal film is provided.

[0007] According to various embodiments, there is provided an RF PCB which improves adhesion between components and improves bending life and bendability by applying a composite film having a metal film subjected to a heterogeneous surface treatment.

[0008] According to various embodiments, there is provided an electronic device which improves bending life and bendability of a hinge portion having a repeated bending structure.

[0009] The technical objectives to be achieved are not limited to those mentioned above, and other technical objectives not mentioned above will be clearly understood by ordinary technicians in the field from the following description.

[0010] According to one embodiment, a composite film includes: a base film layer; a first metal film layer formed on one surface of the base film layer; and a second metal film layer formed on an opposite surface. The first metal film layer and the second metal film layer may include a soft etching treated region and an oxide surface treated region, and the soft etching treated region and the oxide surface treated region may have different surface roughnesses.

[0011] According to an embodiment, an RFPCB includes: a composite film; a flexible region formed on at least a portion of at least one surface of the composite film; and a rigid region formed on at least a portion of at least one surface of the composite film. The composite film may include: a base film layer; a first metal film layer formed on one surface of the base film layer; and a second metal film layer formed on an opposite surface, wherein the first metal film layer and the second metal film layer may include a soft etching treated region and an oxide surface treated region, and the soft etching treated region and the oxide surface treated region may have different surface roughnesses.

[0012] According to an embodiment, an electronic device includes: a flexible display; and the composite film of the RFPCB or the RFPCB.

[0013] Advantageous Effects of the Invention According to an embodiment, a composite film that can be applied to an electronic device including a flexible display (e.g., a television (TV), a smart phone, a watch, a tablet personal computer (PC)) and can improve bending life and flexibility when applied to a hinge part of an electronic device that undergoes repeated bending, and a rigid flexible printed circuit board (RFPCB) to which the composite film is applied can be provided.

[0014] Effects to be achieved are not limited to those described above, and other effects not mentioned above will be clearly understood by those of ordinary skill in the art from the following description. BRIEF DESCRIPTION OF THE DRAWINGS

[0015] Figure 1 is a block diagram illustrating electronic devices in a network environment according to various embodiments.

[0016] Figure 2 is a diagram of an electronic device in an unfolded state according to various embodiments.

[0017] Figure 3 is a diagram of an electronic device in a folded state according to various embodiments.

[0018] Figure 4a and Figure 4b 2 is a perspective view illustrating examples of a fully unfolded state and a partially unfolded state (or an intermediate state) of an electronic device according to various embodiments.

[0019] Figure 5 are cross-sectional views illustrating configurations of composite films according to various embodiments.

[0020] Figure 6 is a cross-sectional view illustrating a configuration of a rigid flexible printed circuit board (RFPCB) including a composite film according to various embodiments.

[0021] Figure 7a is a perspective view illustrating a state in which an RFPCB is disposed between a hinge housing and a hinge assembly of a foldable electronic device according to various embodiments.

[0022] Figure 7b is a cross-sectional view schematically illustrating a state in which an RFPCB is disposed between a hinge housing and a hinge assembly of a foldable electronic device according to various embodiments.

[0023] Figure 8 is a flow chart of operations for making a composite membrane according to various embodiments.

[0024] Fig. 9 is a flow chart of operations for manufacturing an RF PCB according to various embodiments. DETAILED DESCRIPTION

[0025] Hereinafter, the embodiments will be described in detail with reference to the accompanying drawings. When describing the embodiments with reference to the accompanying drawings, the same reference numerals denote the same elements, and repeated descriptions thereof will be omitted.

[0026] Figure 1 is a block diagram illustrating an electronic device 101 in a network environment 100 according to various embodiments.

[0027] Reference Figure 1 , the electronic device 101 in the network environment 100 may communicate with the electronic device 102 via the first network 198 (e.g., a short-range wireless communication network), or communicate with the electronic device 104 or the server 108 via the second network 199 (e.g., a long-range wireless communication network). According to an embodiment, the electronic device 101 may communicate with the electronic device 104 via the server 108. According to an embodiment, the electronic device 101 may include a processor 120, a memory 130, an input module 150, a sound output module 155, a display module 160, an audio module 170, a sensor module 176, an interface 177, a connection terminal 178, a haptic module 179, a camera module 180, a power management module 188, a battery 189, a communication module 190, a user identification module (SIM) 196, or an antenna module 197. In some embodiments, at least one of the above components (e.g., the connection terminal 178) may be omitted from the electronic device 101, or one or more other components may be added to the electronic device 101. In some embodiments, some of the above-described components (eg, sensor module 176, camera module 180, or antenna module 197) may be integrated into a single component (eg, display module 160).

[0028] The processor 120 may run, for example, software (e.g., program 140) to control at least one other component (e.g., hardware component or software component) of the electronic device 101 connected to the processor 120, and may perform various data processing or calculations. According to an embodiment, as at least part of the data processing or calculation, the processor 120 may store a command or data received from another component (e.g., sensor module 176 or communication module 190) in the volatile memory 132, process the command or data stored in the volatile memory 132, and store the resultant data in the non-volatile memory 134. According to an embodiment, the processor 120 may include a main processor 121 (e.g., a central processing unit (CPU) or an application processor (AP)) or an auxiliary processor 123 (e.g., a graphics processing unit (GPU), a neural processing unit (NPU), an image signal processor (ISP), a sensor hub processor, or a communication processor (CP)) that operates independently or in conjunction with the main processor 121. For example, when the electronic device 101 includes a main processor 121 and an auxiliary processor 123, the auxiliary processor 123 may be adapted to consume less power than the main processor 121, or adapted to be dedicated to a specific function. The auxiliary processor 123 may be implemented separately from the main processor 121, or as part of the main processor 121.

[0029] When the main processor 121 is in an inactive (e.g., sleep) state, the auxiliary processor 123 (rather than the main processor 121) may control at least some of the functions or states related to at least one component among the components of the electronic device 101 (e.g., the display module 160, the sensor module 176, or the communication module 190), or when the main processor 121 is in an active state (e.g., running an application), the auxiliary processor 123 may control at least some of the functions or states related to at least one component among the components of the electronic device 101 (e.g., the display module 160, the sensor module 176, or the communication module 190) together with the main processor 121. According to an embodiment, the auxiliary processor 123 (e.g., ISP or CP) may be implemented as part of another component (e.g., camera module 180 or communication module 190) that is functionally related to the auxiliary processor 123. According to an embodiment, the auxiliary processor 123 (e.g., NPU) may include a hardware structure dedicated to artificial intelligence model processing. The artificial intelligence model may be generated through machine learning. For example, such learning may be performed by the electronic device 101 where the artificial intelligence is executed or via a separate server (e.g., server 108). The learning algorithm may include, but is not limited to, supervised learning, unsupervised learning, semi-supervised learning, or reinforcement learning, for example. The artificial intelligence model may include multiple artificial neural network layers. The artificial neural network may include, for example, a deep neural network (DNN), a convolutional neural network (CNN), a recurrent neural network (RNN), a restricted Boltzmann machine (RBM), a deep belief network (DBN), a bidirectional recurrent deep neural network (BRDNN), or a deep Q network or a combination of two or more thereof, but is not limited thereto. Additionally or optionally, the artificial intelligence model may include a software structure in addition to a hardware structure.

[0030] The memory 130 may store various data used by at least one component of the electronic device 101 (e.g., the processor 120 or the sensor module 176). The various data may include, for example, software (e.g., the program 140) and input data or output data for commands related thereto. The memory 130 may include a volatile memory 132 or a nonvolatile memory 134.

[0031] The program 140 may be stored as software in the memory 130 , and may include, for example, an operating system (OS) 142 , middleware 144 , or applications 146 .

[0032] The input module 150 may receive a command or data to be used by another component (e.g., the processor 120) of the electronic device 101 from outside (e.g., a user) of the electronic device 101. The input module 150 may include, for example, a microphone, a mouse, a keyboard, a key (e.g., a button), or a digital pen (e.g., a stylus).

[0033] The sound output module 155 can output sound signals to the outside of the electronic device 101. The sound output module 155 may include, for example, a speaker or a receiver. The speaker can be used for general purposes such as playing multimedia or playing records. The receiver can be used to receive incoming calls. Depending on the embodiment, the receiver can be implemented as a separate part from the speaker, or as part of the speaker.

[0034] The display module 160 may visually provide information to the outside of the electronic device 101 (e.g., a user). The display module 160 may include, for example, a display, a holographic device, or a projector, and a control circuit for controlling a corresponding one of the display, the holographic device, and the projector. According to an embodiment, the display module 160 may include a touch sensor adapted to sense a touch or a pressure sensor adapted to measure the strength of a force caused by a touch.

[0035] The audio module 170 may convert sound into an electrical signal, or vice versa. According to an embodiment, the audio module 170 may obtain sound via the input module 150, or output sound via the sound output module 155 or an external electronic device (e.g., the electronic device 102, such as a speaker or earphone) directly or wirelessly connected to the electronic device 101.

[0036] The sensor module 176 may detect an operating state (e.g., power or temperature) of the electronic device 101 or an environmental state (e.g., a state of a user) outside the electronic device 101, and generate an electrical signal or data value corresponding to the detected state. According to an embodiment, the sensor module 176 may include, for example, a gesture sensor, a gyro sensor, an atmospheric pressure sensor, a magnetic sensor, an acceleration sensor, a grip sensor, a proximity sensor, a color sensor, an infrared (IR) sensor, a biometric sensor, a temperature sensor, a humidity sensor, or an illumination sensor.

[0037] The interface 177 may support one or more specific protocols to be used to directly (e.g., wired) or wirelessly couple the electronic device 101 to an external electronic device (e.g., the electronic device 102). According to an embodiment, the interface 177 may include, for example, a high-definition multimedia interface (HDMI), a universal serial bus (USB) interface, a secure digital (SD) card interface, or an audio interface.

[0038] The connection end 178 may include a connector, wherein the electronic device 101 can be physically connected to an external electronic device (e.g., the electronic device 102) via the connector. According to an embodiment, the connection end 178 may include, for example, an HDMI connector, a USB connector, an SD card connector, or an audio connector (e.g., a headphone connector).

[0039] The haptic module 179 may convert the electric signal into mechanical stimulation (eg, vibration or motion) or electric stimulation that can be recognized by the user via his or her sense of touch or kinesthetic sense. According to an embodiment, the haptic module 179 may include, for example, a motor, a piezoelectric element, or an electric stimulator.

[0040] The camera module 180 may capture still images or moving images. According to embodiments, the camera module 180 may include one or more lenses, image sensors, ISPs, or flashes.

[0041] The power management module 188 may manage power supply to the electronic device 101. According to an embodiment, the power management module 188 may be implemented as, for example, at least a part of a power management integrated circuit (PMIC).

[0042] The battery 189 may power at least one component of the electronic device 101. According to an embodiment, the battery 189 may include, for example, a non-rechargeable primary battery, a rechargeable secondary battery, or a fuel cell.

[0043] The communication module 190 may support establishing a direct (e.g., wired) communication channel or a wireless communication channel between the electronic device 101 and an external electronic device (e.g., electronic device 102, electronic device 104, or server 108), and perform communication via the established communication channel. The communication module 190 may include one or more CPs that can operate independently with the processor 120 (e.g., AP) and support direct (e.g., wired) communication or wireless communication. According to an embodiment, the communication module 190 may include a wireless communication module 192 (e.g., a cellular communication module, a short-range wireless communication module, or a global navigation satellite system (GNSS) communication module) or a wired communication module 194 (e.g., a local area network (LAN) communication module or a power line communication (PLC) module). A corresponding one of these communication modules may communicate with the external electronic device 104 via a first network 198 (e.g., a short-range communication network such as Bluetooth, Wireless Fidelity (Wi-Fi) Direct, or Infrared Data Association (IrDA)) or a second network 199 (e.g., a long-range communication network such as a traditional cellular network, a 5G network, a next-generation communication network, the Internet, or a computer network (e.g., a LAN or a Wide Area Network (WAN))). These various types of communication modules may be implemented as a single component (e.g., a single chip), or may be implemented as a plurality of components (e.g., a plurality of chips) separated from each other. The wireless communication module 192 may identify and authenticate the electronic device 101 in a communication network such as the first network 198 or the second network 199 using user information (e.g., an International Mobile Subscriber Identity (IMSI)) stored in the SIM 196.

[0044] The wireless communication module 192 can support 5G networks after 4G networks and next-generation communication technologies (e.g., new radio (NR) access technology). NR access technology can support enhanced mobile broadband (eMBB), massive machine type communication (mMTC), or ultra-reliable low-latency communication (URLLC). The wireless communication module 192 can support high-frequency bands (e.g., millimeter wave bands) to achieve, for example, high data transmission rates. The wireless communication module 192 can support various technologies for ensuring performance on high-frequency bands, such as, for example, beamforming, massive multiple-input multiple-output (massive MIMO), full-dimensional MIMO (FD-MIMO), array antennas, analog beamforming, or massive antennas. The wireless communication module 192 can support various requirements specified in the electronic device 101, an external electronic device (e.g., electronic device 104), or a network system (e.g., a second network 199). According to an embodiment, the wireless communication module 192 may support a peak data rate for implementing eMBB (e.g., 20 Gbps or greater), loss coverage for implementing mMTC (e.g., 164 dB or less), or U-plane delay for implementing URLLC (e.g., 0.5 ms or less for each of the downlink (DL) and uplink (UL), or 1 ms or less for a round trip).

[0045] The antenna module 197 may transmit or receive a signal or power to or from the outside of the electronic device 101 (e.g., an external electronic device). According to an embodiment, the antenna module 197 may include an antenna including a radiation element including a conductive material or a conductive pattern formed in or on a substrate (e.g., a printed circuit board (PCB)). According to an embodiment, the antenna module 197 may include a plurality of antennas (e.g., an array antenna). In this case, at least one antenna suitable for a communication scheme used in a communication network (such as the first network 198 or the second network 199) may be selected from the plurality of antennas by, for example, the communication module 190. A signal or power may be transmitted or received between the communication module 190 and the external electronic device via the selected at least one antenna. According to an embodiment, another component (e.g., a radio frequency integrated circuit (RFIC)) other than the radiation element may be additionally formed as a part of the antenna module 197.

[0046] According to an embodiment, the antenna module 197 may form a millimeter wave antenna module. According to an embodiment, the millimeter wave antenna module may include a PCB, an RFIC, and a plurality of antennas (e.g., an array antenna), wherein the RFIC is disposed on a first surface (e.g., a bottom surface) of the PCB, or is adjacent to the first surface and can support a specified high frequency band (e.g., a millimeter wave band), and the plurality of antennas are disposed on a second surface (e.g., a top surface or a side surface) of the PCB, or is adjacent to the second surface and can transmit or receive signals of the specified high frequency band.

[0047] At least some of the above components may be coupled to each other via an inter-peripheral communication scheme (e.g., a bus, a general purpose input output (GPIO), a serial peripheral interface (SPI), or a mobile industry processor interface (MIPI)) and communicatively transmit signals (e.g., commands or data) therebetween.

[0048] According to an embodiment, a command or data may be sent or received between the electronic device 101 and the external electronic device 104 via the server 108 connected to the second network 199. Each of the electronic device 102 or the electronic device 104 may be a device of the same type as the electronic device 101, or a device of a different type from the electronic device 101. According to an embodiment, all or some operations to be executed by the electronic device 101 may be executed on one or more external electronic devices (e.g., the external devices 102 and 104 and the server 108). For example, if the electronic device 101 needs to automatically execute a function or service or needs to execute a function or service in response to a request from a user or another device, the electronic device 101 may request the one or more external electronic devices to execute at least part of the function or service instead of executing the function or service, or the electronic device 101 may request the one or more external electronic devices to execute at least part of the function or service in addition to executing the function or service. The one or more external electronic devices receiving the request may execute at least part of the requested function or service, or execute another function or another service related to the request, and transmit the result of the execution to the electronic device 101. The electronic device 101 may provide the result as at least a partial reply to the request with or without further processing the result. To this end, cloud computing technology, distributed computing technology, mobile edge computing (MEC) technology, or client-server computing technology, for example, may be used. The electronic device 101 may use, for example, distributed computing or mobile edge computing to provide ultra-low latency services. In another embodiment, the external electronic device 104 may include an Internet of Things (IoT) device. The server 108 may be an intelligent server using machine learning and / or neural networks. According to an embodiment, the external electronic device 104 or the server 108 may be included in the second network 199. The electronic device 101 may be applied to intelligent services (e.g., smart homes, smart cities, smart cars, or healthcare) based on 5G communication technology or IoT-related technologies.

[0049] Figure 2 is a diagram of the electronic device 200 in an unfolded state according to various embodiments. Figure 3 is a diagram of an electronic device 200 in a folded state according to various embodiments. Figure 4a and Figure 4b 2 is a perspective view illustrating examples of a fully unfolded state and a partially unfolded state (or an intermediate state) of the electronic device 200 according to various embodiments.

[0050] Figures 2 to 4a The electronic device 200 may be Figure 1An example of an electronic device 101 is shown, and may be a foldable or bendable electronic device.

[0051] exist Figure 4a and Figure 4b , a spatial coordinate system defined by mutually orthogonal X-axis, Y-axis, and Z-axis is shown. Here, the X-axis may represent the width direction of the electronic device, the Y-axis may represent the length direction of the electronic device, and the Z-axis may represent the height (or thickness) direction of the electronic device. In the following description, the "first direction" may refer to a direction parallel to the Z-axis.

[0052] Reference Figure 2 and Figure 3 In an embodiment, the electronic device 200 may include a foldable housing 201 and a flexible or foldable display 250 (hereinafter referred to as “display” 250 ) disposed in a space formed by the foldable housing 201 (e.g., Figure 1 According to an embodiment, a surface on which the display 250 is provided (or a surface on which the display 250 is viewed from outside the electronic device 200) may be defined as a front surface of the electronic device 200. In addition, a surface opposite to the front surface may be defined as a rear surface of the electronic device 200. Furthermore, a surface surrounding a space between the front surface and the rear surface may be defined as a side surface of the electronic device 200.

[0053] According to an embodiment, the foldable housing 201 may include a first housing structure 210, a second housing structure 220 including a sensor area 222, a first rear cover 215, a second rear cover 225, and a hinge structure 230. Here, the hinge structure 230 may include a hinge cover covering a foldable portion of the foldable housing 201. The foldable housing 201 of the electronic device 200 is not limited to Figure 2 and Figure 3 The shapes and combinations shown in , and can be implemented in different shapes or according to different combinations of components. For example, in another embodiment, the first housing structure 210 and the first back cover 215 can be formed integrally, and the second housing structure 220 and the second back cover 225 can be formed integrally.

[0054] According to various embodiments, the first housing structure 210 may be connected to the hinge structure 230 and may include a first surface facing a first direction and a second surface facing a second direction opposite to the first direction. The second housing structure 220 may be connected to the hinge structure 230 and may include a third surface facing a third direction and a fourth surface facing a fourth direction opposite to the third direction. The second housing structure 220 may rotate around the hinge structure 230 relative to the first housing structure 210. The state of the electronic device 200 may be changed to a folded state or an unfolded state.

[0055] According to an embodiment, in a state where the electronic device 200 is completely folded, the first surface may face the third surface, and in a state where the electronic device 200 is completely unfolded, the third direction may be the same as the first direction.

[0056] According to various embodiments, the first housing structure 210 and the second housing structure 220 are arranged on both sides relative to the folding axis A, and may generally be symmetrical relative to the folding axis A. As described below, the angle or distance between the first housing structure 210 and the second housing structure 220 may vary depending on whether the electronic device 200 is in an unfolded state, a folded state, or an intermediate state (e.g., a partially folded state or a partially unfolded state). According to an embodiment, unlike the first housing structure 210, the second housing structure 220 may additionally include a sensor area 222 in which various sensors are arranged. However, the first housing structure 210 and the second housing structure 220 may be symmetrical to each other in an area other than the sensor area 222. In another embodiment, the sensor area 222 may be additionally arranged in at least a portion of the second housing structure 220 or replaced by at least a portion of the second housing structure 220. The sensor area 222 may include, for example, a camera hole area, a sensor hole area, an under-screen camera (UDC) area, and / or an under-screen sensor (UDS) area.

[0057] According to various embodiments, Figure 2 As shown, the first housing structure 210 and the second housing structure 220 may together form a recess for accommodating the display 250. In an embodiment, due to the sensor area 222, the recess may have at least two different widths in a direction perpendicular to the folding axis A. For example, the recess may have a first width W between a first portion 210a of the first housing structure 210 parallel to the folding axis A and a first portion 220a of the second housing structure 220 formed on the periphery of the sensor area 222. 1 , and has a second width W formed by a second portion 210 b of the first housing structure 210 that does not correspond to the sensor area 222 and is parallel to the folding axis A and a second portion 220 b of the second housing structure 220 2 In this example, the second width W 2 Can be larger than the first width W 1. In an embodiment, the first portion 220a and the second portion 220b of the second housing structure 220 may be at different distances from the folding axis A. The width of the recess is not limited to the example shown. In another embodiment, the recess may have multiple widths due to the shape of the sensor area 222 or the asymmetric portions of the first housing structure 210 and the second housing structure 220. According to various embodiments, the sensor area 222 may be formed to have a predetermined area adjacent to one corner of the second housing structure 220. However, the arrangement, shape and size of the sensor area 222 are not limited to the example shown. For example, in another embodiment, the sensor area 222 may be disposed at another corner of the second housing structure 220 or in a predetermined area between the upper corner and the lower corner. In an embodiment, a component embedded in the electronic device 200 to perform various functions may be exposed to the front surface of the electronic device 200 through the sensor area 222 or through one or more openings disposed in the sensor area 222. In various embodiments, the component may include various types of sensors. The sensor may include, for example, at least one of a front camera, a receiver, or a proximity sensor. According to various embodiments, the sensor region 222 may not be included in the second housing structure 220 , or may be formed at a position different from that shown in the drawings.

[0058] According to various embodiments, at least a portion of the first housing structure 210 and the second housing structure 220 may be formed of a metal material or a non-metal material having a selected stiffness to support the display 250. At least a portion formed of a metal material may provide a ground plane for the electronic device 200 and may be electrically connected to a ground line formed on a printed circuit board (PCB) disposed inside the foldable housing 201.

[0059] According to various embodiments, the first back cover 215 may be disposed on the rear surface of the electronic device 200 on one side of the folding axis A, and may have, for example, a substantially rectangular perimeter that may be surrounded by the first housing structure 210. Similarly, the second back cover 225 may be disposed on the rear surface of the electronic device 200 on the other side of the folding axis A, and may have a perimeter that may be surrounded by the second housing structure 220.

[0060] According to various embodiments, the first rear cover 215 and the second rear cover 225 may be substantially symmetrical with respect to the folding axis A. However, the first rear cover 215 and the second rear cover 225 are not necessarily symmetrical with each other, and in another embodiment, the electronic device 200 may include various shapes of the first rear cover 215 and the second rear cover 225. In another embodiment, the first rear cover 215 may be integrally formed with the first housing structure 210, and the second rear cover 225 may be integrally formed with the second housing structure 220.

[0061] According to various embodiments, the first back cover 215, the second back cover 225, the first housing structure 210, and the second housing structure 220 may form a space in which various components of the electronic device 200 (e.g., a PCB, an antenna module, a sensor module, or a battery) are arranged. In an embodiment, one or more components may be disposed or visually exposed on the rear surface of the electronic device 200. For example, at least a portion of the sub-display may be visually exposed through the first rear area 216 of the first back cover 215. In another embodiment, one or more components or sensors may be visually exposed through the second rear area 226 of the second back cover 225. In various embodiments, the sensor may include a proximity sensor and / or a rear camera module.

[0062] According to various embodiments, the front camera exposed to the front surface of the electronic device 200 through one or more openings provided in the sensor area 222 or the rear camera exposed through the second rear area 226 of the second rear cover 225 may include one or more lenses, image sensors and / or ISPs. The flash may include, for example, a light emitting diode (LED) or a xenon lamp. In some embodiments, two or more lenses (e.g., an infrared camera lens, a wide-angle lens, and a telephoto lens) and an image sensor may be provided on one surface of the electronic device 200.

[0063] refer to Figure 3 , a hinge cover may be provided between the first housing structure 210 and the second housing structure 220 to cover internal components (e.g., hinge structure 230). According to an embodiment, according to a state of the electronic device 200 (e.g., an unfolded state, an intermediate state, or a folded state), the hinge structure 230 may be covered by a portion of the first housing structure 210 and a portion of the second housing structure 220, or may be exposed to the outside.

[0064] According to an embodiment, when the electronic device 200 is in a state such as Figure 2 In the unfolded state (e.g., fully unfolded state) shown in FIG. 1 , the hinge structure 230 may be covered by the first shell structure 210 and the second shell structure 220 and not be exposed. In another example, when the electronic device 200 is in a folded state (e.g., fully folded state), as shown in FIG. Figure 3 As shown, the hinge structure 230 can be exposed to the outside and located between the first housing structure 210 and the second housing structure 220. In another example, when the first housing structure 210 and the second housing structure 220 are in an intermediate state where the first housing structure 210 and the second housing structure 220 are folded at a certain angle, a portion of the hinge structure 230 can be exposed to the outside between the first housing structure 210 and the second housing structure 220. In this example, the exposed area can be smaller than the area exposed in the fully folded state. In an embodiment, the hinge cover 230 can have a curved surface.

[0065] According to various embodiments, the display 250 may be disposed in a space formed by the foldable housing 201. For example, the display 250 may be placed on a recess formed by the foldable housing 201 and may be viewed from the outside through the front surface of the electronic device 200. For example, the display 250 may constitute a large portion of the front surface of the electronic device 200. Therefore, the front surface of the electronic device 200 may include the display 250, and a partial area of ​​the first housing structure 210 adjacent to the display 250, and a partial area of ​​the second housing structure 220. In addition, the rear surface of the electronic device 200 may include the first rear cover 215, a partial area of ​​the first housing structure 210 adjacent to the first rear cover 215, the second rear cover 225, and a partial area of ​​the second housing structure 220 adjacent to the second rear cover 225.

[0066] According to various embodiments, the display 250 may refer to a display having at least a partial area that can be deformed into a flat surface or a curved surface. In an embodiment, the display 250 may include a folding area 253, a folding area 254 disposed on one side of the folding area 253 (for example, Figure 2 The first area 251 is provided on the left side of the folding area 253 shown in FIG. 1 , and the first area 251 is provided on the other side of the folding area 253 (for example, on the left side of the folding area 253 shown in FIG. 1 ). Figure 2 The second area 252 is on the right side of the folding area 253 shown in FIG.

[0067] However, Figure 2 Such area division of the display 250 shown in FIG. 1 is merely an example, and the display 250 may be divided into a plurality of areas (eg, four or more areas or two areas) according to its structure or function. Figure 2 In the illustrated embodiment, the display 250 can be divided into multiple regions based on a folding region 253 extending parallel to the folding axis A. In another embodiment, the display 250 can be divided into multiple regions based on another folding axis (e.g., a folding axis parallel to the width direction of the electronic device).

[0068] According to various embodiments, the display 250 may be coupled to a touch panel or arranged adjacent to the touch panel, the touch panel including a touch sensing circuit and a pressure sensor for measuring the intensity (pressure) of the touch. For example, as an example of a touch panel, the display 250 may be coupled to a touch panel for detecting an electromagnetic resonance (EMR) type stylus or arranged adjacent to the touch panel.

[0069] According to various embodiments, the first region 251 and the second region 252 may have a globally symmetrical shape around the folding region 253. However, unlike the first region 251, the second region 252 may include a notch cut according to the presence of the sensor region 222, but may be symmetrical with the first region 251 in other regions. In other words, the first region 251 and the second region 252 may include mutually symmetrical portions and mutually asymmetrical portions.

[0070] According to various embodiments, the edge thickness of each of the first region 251 and the second region 252 may be different from the edge thickness of the folding region 253. The edge thickness of the folding region 253 may be less than the edge thickness of the first region 251 and the second region 252. For example, when viewed in a cross section of the first region 251 and the second region 252, the first region 251 and the second region 252 may be asymmetric in thickness. For example, the edge of the first region 251 may be formed to have a first radius of curvature, and the edge of the second region 252 may be formed to have a second radius of curvature different from the first radius of curvature. In another embodiment, when viewed in a cross section of the first region 251 and the second region 252, the first region 251 and the second region 252 may be symmetric in thickness.

[0071] Hereinafter, each region of the display 250 and operations of the first case structure 210 and the second case structure 220 according to a state (eg, a folded state, an unfolded state, or an intermediate state) of the electronic device 200 will be described.

[0072] According to various embodiments, when the electronic device 200 is in the unfolded state (eg, Figure 2 ), the first housing structure 210 and the second housing structure 220 may be arranged to face substantially the same direction while forming an angle of 180 degrees. The surface of the first area 251 of the display 250 and the surface of the second area 252 of the display 250 may face the same direction (e.g., the front direction of the electronic device) while forming 180 degrees. The folding area 253 may be combined with the first area 251 and the second area 252 to form substantially the same plane. In another embodiment, when the electronic device 200 is in a flat state, the first housing structure 210 and the second housing structure 220 may be relatively folded while rotating a predetermined angle (e.g., about 360 degrees) relative to each other, so that the first back cover 215 and the second back cover 225 face each other. In other words, the first area 251 and the second area 252 of the display may be arranged to face opposite directions relative to each other.

[0073] According to various embodiments, when the electronic device 200 is in a folded state (eg, Figure 3), the first housing structure 210 and the second housing structure 220 may be arranged to face each other. The surface of the first area 251 and the surface of the second area 252 of the display 250 may face each other while forming a narrow angle (e.g., an angle between about 0 degrees and about 10 degrees). For example, at least a portion of the folding area 253 may form a curved surface having a predetermined curvature.

[0074] According to various embodiments, when the electronic device 200 is in the intermediate state, the first housing structure 210 and the second housing structure 220 may be arranged to form a certain angle (e.g., about 90 degrees) therebetween. The surface of the first region 251 and the surface of the second region 252 of the display 250 may form an angle that is larger than the angle in the folded state and smaller than the angle in the unfolded state. At least a portion of the folded region 253 may include a curved surface having a predetermined curvature, and the curvature may be smaller than the curvature in the folded state.

[0075] Figure 4a The electronic device 200 is shown in a fully unfolded state, and Figure 4b 2 shows an intermediate state where the electronic device 200 is partially unfolded. As described above, the state of the electronic device 200 can be changed to a folded state or an unfolded state. According to an embodiment, when the electronic device 200 is unfolded along a folding axis (e.g., Figure 2 When viewed in the direction of the axis A of the electronic device 200, the electronic device 200 can be folded in two types, namely, an "inward folding" type in which the front surface of the electronic device 200 is folded to form an acute angle and an "outward folding" type in which the front surface of the electronic device 200 is folded to form an obtuse angle. In an example, in a state where the electronic device 200 is folded in the inward folding type, the first surface of the first shell structure 210 can face the third surface of the second shell structure 220. In a fully unfolded state, the first surface of the first shell structure 210 and the third surface of the second shell structure 220 can face the same direction (e.g., a direction parallel to the z-axis).

[0076] In another example, when the electronic device 200 is folded in an outward folding type, the second surface of the first housing structure 210 may face the fourth surface of the second housing structure 220 .

[0077] In addition, although not shown in the drawings, the electronic device 200 may include a plurality of hinge axes (eg, including Figure 2 In the embodiment, the electronic device 200 may be folded in a "multi-fold" type that combines an inner folding type and an outer folding type. In addition, although not shown, when the electronic device 200 is viewed from the top, the hinge axes may be formed longitudinally or transversely. In the example, all of the multiple hinge axes may be arranged in the same direction. In another example, some of the multiple hinge axes may be arranged in different directions and folded.

[0078] The inner folding type may refer to a state in which the display 250 is not exposed to the outside in a completely folded state. The outer folding type may refer to a state in which the display 250 is exposed to the outside in a completely folded state. Figure 4b The electronic device 200 is shown in an intermediate state where it is partially unfolded during the inward folding process.

[0079] Although a state in which the electronic device 200 is folded in an inner folding type will be described below for convenience, it should be noted that the description can be similarly applied to a state in which the electronic device 200 is folded in an outer folding type.

[0080] Figure 5 is a cross-sectional view of a composite membrane according to various embodiments, and Figure 5 Will be applied to Figure 6 4 is a cross-sectional view of a composite film 300 of a composite film layer 410 of a rigid flexible printed circuit board (RFPCB) 400.

[0081] Reference Figure 5 According to various embodiments, the composite film 300 may include a base film layer 310 , and metal thin film layers 320 and 330 on both surfaces of the base film layer 310 .

[0082] According to various embodiments, the base film layer 310 is a flexible base substrate including an insulating polymer, and may be, for example, polyimide (PI), polycarbonate (PC), polypropylene (PP), polyethylene terephthalate (PET), or polymethyl methacrylate (PMMA), but is not limited thereto. According to various embodiments, the thickness of the base film layer 310 is about 7.5 μm to about 25 μm; about 7.5 μm to about 20 μm; about 7.5 μm to about 15 μm; about 7.5 μm to about 12 μm; about 7.5 μm to about 10 μm; about 8 μm to about 20 μm; about 9 μm to about 20 μm; about 11 μm to about 20 μm; about 13 μm to about 20 μm; about 16 μm to about 20 μm; or about 18 μm to about 20 μm, so as to support the metal film layer and when applied to the hinge portion (e.g., Figure 3 The hinge structure 230 of the electronic device 200, or Figure 7a and Figure 7b Provides bendability between the hinge housing 583 and the hinge assembly 584 of the electronic device 580.

[0083] According to various embodiments, a conductive pattern may be further formed on at least a portion of at least one of the metal film layers 320 and 330, and this may be formed by patterning the metal film layers 320 and 330 or forming a conductive pattern layer on the metal film layers 320 and 330. For example, the conductive pattern may be formed by patterning the copper foil of the flexible copper clad laminate (FCCL) to form a pattern (e.g., an internal circuit pattern). For example, the conductive pattern layer (e.g., an internal circuit pattern) may be formed by performing printing with a material containing a conductive metal (e.g., copper or copper alloy) component used in the PCB field.

[0084] According to various embodiments, an adhesive layer (not shown) may be further included between the metal film layers 320 and 330 and the base film layer 310, and the adhesive layer may be an insulating material. According to various embodiments, the metal film layers 320 and 330 may be a single layer or a plurality of layers. According to various embodiments, the thickness of each of the metal film layers 320 and 330 may be about 6 μm to about 36 μm; about 6 μm to about 34 μm; about 6 μm to about 32 μm; about 6 μm to about 30 μm; about 6 μm to about 28 μm; about 6 μm to about 25 μm; about 6 μm to about 10 μm; about 6 μm to about 8 μm; about 7 μm to about 36 μm; about 9 μm to about 36 μm; about 12 μm to about 36 μm; about 15 μm to about 36 μm; about 18 μm to about 36 μm; about 20 μm to about 36 μm; or about 25 μm to about 36 μm.

[0085] According to various embodiments, the surfaces of the metal film layers 320 and 330 may include two or more regions having different surface properties. For example, the surfaces of the metal film layers 320 and 330 may include two or more regions having different surface roughness. This may be applied to components requiring flexibility (e.g., RF PCB) or hinge parts of electronic devices (e.g., Figure 3 The hinge structure 230 of the electronic device 200, or Figure 7a and Figure 7b The invention provides an electronic device 580 of the present invention, wherein the hinge housing 583 and the hinge assembly 584 are provided to improve adhesion and bendability. For example, the bending life and bendability in the repeated bending area of ​​the hinge part having a bending structure can be improved, and an RFPCB with improved adhesion between components can be provided.

[0086] According to various embodiments, each of the two or more regions having different surface characteristics (eg, surface roughness) of the metal thin film layers 320 and 330 may be formed in a single region or in a plurality of regions (eg, Figure 5 322, 332, 321a, 321b, 331a and 331b). Multiple regions (e.g., Figure 5 322, 332, 321a, 321b, 331a and 331b).

[0087] According to various embodiments, the metal thin film layers 320 and 330 may include two or more regions (eg, Figure 5 For example, the surface treatment process may be selected from a soft etching process and an oxide surface treatment process, the surfaces of the metal film layers 320 and 330 may be etched by the surface treatment process to form surface roughness, and the degree of surface roughness (e.g., an average value of the surface roughness or an etching depth) may be controlled according to the etching amount.

[0088] According to various embodiments, a portion of the surface of the metal thin film layers 320 and 330 may be surface treated by a soft etching process, and wet etching, flash etching, or a rapid etching method may be used for the soft etching process. In some examples, in wet etching, a soft etchant containing an inorganic acid or an organic acid may be used. For example, a soft etchant such as a persulfate / sulfuric acid type (e.g., H 2 O 2 and H 2 SO 4 ), sodium persulfate / sulfuric acid type (e.g., Na 2 S 2 O 8 and H 2 SO 4 ) to perform the soft etching process, but is not limited thereto. According to various embodiments, the surfaces of the metal film layers 320 and 330 other than the areas subjected to the surface treatment by the soft etching process may be optionally subjected to an oxide treatment, and the oxide surface treatment may be a brown oxide process or a black oxide process. In some examples, a brown oxide reactant may be used, for example, the brown oxide reactant may include peroxide (H 2 O 2 In some examples, a black oxide reactant may be used. For example, the black oxide reactant may include an oxidant and an alkali. The oxidant may include NaClO, NaClO 2 、NaClO 3 、KClO、KClO 2 and KClO 3 , and the base may include sodium hydroxide, potassium hydroxide, barium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, or tetraethylammonium hydroxide as a hydroxide, but is not limited thereto.

[0089] According to various embodiments, the surface roughness of the soft etched area and the oxide surface treated area may be different from each other. For example, the soft etched area may have a lower etching amount than the oxide surface treated area, resulting in a lower surface roughness, which can improve bendability. The oxide surface treated area may form a large surface roughness to improve adhesion.

[0090] According to various embodiments, reference Figure 5 , the metal film layers 320 and 330 may include a first metal film layer 320 formed on one surface of the base film layer 310 and a second metal film layer 330 formed on the opposite surface. The surfaces of the first metal film layer 320 and the second metal film layer 330 may include two or more regions with different surface characteristics (e.g., surface roughness) according to the surface treatment method. For example, the surfaces of the first metal film layer 320 and the second metal film layer 330 may include first oxide surface-treated regions 321a and 331a and second oxide surface-treated regions 321b and 331b, and the soft etching-treated regions 322 and 332 may be included between the first oxide surface-treated regions 321a and 331a and the second oxide surface-treated regions 321b and 331b. According to various embodiments, the soft etching-treated regions 322 and 332 and the oxide surface-treated regions 321a, 321b, 331a, and 331b may have different surface roughnesses. According to various embodiments, the soft etch processed regions 322 and 332 may include two or more regions having the same or different surface properties (eg, surface roughness). In some examples, the regions 322 and 332 may have the same or different surface properties.

[0091] According to various embodiments, the oxide surface treated regions 321a, 321b, 331a, and 331b may include two or more regions having the same or different surface properties (e.g., surface roughness). In some examples, the regions 321a, 321b, 331a, and 331b may have the same or different surface properties.

[0092] According to various embodiments, the surface roughness of the soft etch treated regions 322 and 332 may be lower than the surface roughness of the oxide surface treated regions 321 a , 321 b , 331 a , and 331 b .

[0093] According to various embodiments, the metal film layers 320 and 330 may include at least one metal or alloy of Cu, Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr. In some examples, the metal film layers 320 and 330 may include copper foil or copper alloy foil. For example, the copper alloy foils 320 and 330 may include Cu; and at least one or more of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr or a mixture thereof (e.g., 0.01 mass % to 1 mass % of the alloy).

[0094] Figure 6 is a cross-sectional view of an RFPCB according to various embodiments. According to various embodiments, Figure 6 The hinge portion of the electronic device (eg, Figure 3 The hinge structure 230 of the electronic device 200, or Figure 7a and Figure 7b A cross-sectional view of the RFPCB 400 to be applied between a hinge housing 583 and a hinge assembly 584 of an electronic device 580.

[0095] Reference Figure 6 According to various embodiments, the RFPCB 400 may include a composite film layer 410 , and rigid regions R and R′ and a flexible region F formed on the composite film layer 410 .

[0096] According to various embodiments, the composite film layer 410 (eg, Figure 5 The composite film 300 may include a base film layer 411 and metal thin film layers 412 and 413 on both surfaces of the base film layer 411.

[0097] According to various embodiments, the base film layer 411 is a flexible base substrate including an insulating polymer, and may be, for example, PI, PC, PP, PET, or PMMA, but is not limited thereto. According to various embodiments, the thickness of the base film layer 310 may be about 7.5 μm to about 25 μm; about 7.5 μm to about 20 μm; about 7.5 μm to about 15 μm; about 7.5 μm to about 12 μm; about 7.5 μm to about 10 μm; about 8 μm to about 25 μm; about 9 μm to about 25 μm; about 10 μm to about 25 μm; about 13 μm to about 25 μm; about 16 μm to about 25 μm; or about 18 μm to about 25 μm. When applied to a hinge portion (e.g., Figure 3 The hinge structure 230 of the electronic device 200, or Figure 7a and Figure 7b When the hinge housing 583 and the hinge assembly 584 of the electronic device 580 are connected, the metal film layer can be supported and bendability can be provided.

[0098] According to various embodiments, a conductive pattern may be further formed on at least a portion of at least one of the metal film layers 412 and 413, and this may be formed by patterning the metal film layers 412 and 413 or forming a conductive pattern layer on the metal film layers 412 and 413. For example, the conductive pattern may be formed by patterning the copper foil of the FCCL to form a pattern (e.g., an internal circuit pattern). For example, the conductive pattern layer (e.g., an internal circuit pattern) may be formed by performing printing with a material containing a conductive metal component (e.g., copper or a copper alloy) used in the PCB field.

[0099] According to various embodiments, an adhesive layer (not shown) may be further included between the metal thin film layers 412 and 413 and the base film layer 411 , and the adhesive layer may be an insulating material.

[0100] According to various embodiments, each of the metal thin film layers 412 and 413 may be a single layer or a plurality of layers. According to various embodiments, each thickness of the metal thin film layers 412 and 413 may be about 6 μm to about 36 μm; about 6 μm to about 34 μm; about 6 μm to about 32 μm; about 6 μm to about 30 μm; about 6 μm to about 28 μm; about 6 μm to about 25 μm; about 6 μm to about 10 μm; about 6 μm to about 8 μm; about 7 μm to about 36 μm; about 9 μm to about 36 μm; about 12 μm to about 36 μm; about 15 μm to about 36 μm; about 18 μm to about 36 μm; about 20 μm to about 36 μm; or about 25 μm to about 36 μm.

[0101] According to various embodiments, the surfaces of the metal film layers 412 and 413 may include two or more regions having different surface properties, and for example, the surfaces of the metal film layers 412 and 413 may include two or more regions having different surface roughness. This may be applied to a portion requiring flexibility (e.g., RF PCB) or a hinge portion of an electronic device (e.g., Figure 3 The hinge structure 230 of the electronic device 200, or Figure 7a and Figure 7b The invention provides an electronic device 580 of the present invention, wherein the hinge housing 583 and the hinge assembly 584 are provided to improve adhesion and bendability. For example, the bending life and bendability in the repeated bending area of ​​the hinge part having a bending structure can be improved, and an RFPCB with improved adhesion between components can be provided.

[0102] According to various embodiments, each of the two or more regions having different surface characteristics (eg, surface roughness) of the metal thin film layers 412 and 413 may be formed in a single region or in a plurality of regions (eg, Figure 6 422, 432, 421a, 421b, 431a and 431b). Multiple areas (for example, Figure 6 422, 432, 421a, 421b, 431a and 431b) can be distinguished by the surface treatment method, but can have different surface roughness.

[0103] According to various embodiments, the metal thin film layers 412 and 413 may include two or more regions (eg, Figure 6 For example, the surface treatment process may be selected from a soft etching process and an oxide surface treatment process, the surfaces of the metal film layers 412 and 413 may be etched by the surface treatment process to form surface roughness, and the degree of surface roughness (e.g., an average value of the surface roughness or an etching depth) may be controlled according to the etching amount.

[0104] According to various embodiments, a portion of the surface of the metal thin film layers 412 and 413 may be surface treated by a soft etching process, and wet etching, flash etching, or a fast etching method may be used for the soft etching process. In some examples, in wet etching, a soft etchant containing an inorganic acid or an organic acid may be used. For example, a soft etchant such as a persulfate / sulfuric acid type (e.g., H 2 O 2 and H 2 SO 4 ), sodium persulfate / sulfuric acid type (e.g., Na 2 S 2 O 8 and H 2 SO 4 ) to perform the soft etching process, but is not limited thereto. According to various embodiments, the surfaces of the metal film layers 412 and 413 other than the areas subjected to the surface treatment by the soft etching process may be optionally subjected to an oxide treatment, and the oxide surface treatment may be a brown oxide process or a black oxide process. In some examples, a brown oxide reactant may be used, for example, the brown oxide reactant may include peroxide (H 2 O 2 In some examples, a black oxide reactant may be used. For example, the black oxide reactant may include an oxidant and an alkali. The oxidant may include NaClO, NaClO 2 、NaClO 3 、KClO、KClO 2 and KClO 3 , and the base may include sodium hydroxide, potassium hydroxide, barium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, or tetraethylammonium hydroxide as a hydroxide, but is not limited thereto.

[0105] According to various embodiments, the surface roughness of the soft etched area and the oxide surface treated area may be different from each other. For example, the soft etched area may have a lower etching amount than the oxide surface treated area, resulting in a lower surface roughness, which can improve bendability. The oxide surface treated area may form a large surface roughness to improve adhesion.

[0106] According to various embodiments, reference Figure 6 , the metal film layers 412 and 413 may include a first metal film layer 412 formed on one surface of the base film layer 411 and a second metal film layer 413 formed on the opposite surface. The surfaces of the first metal film layer 412 and the second metal film layer 413 may include two or more regions with different surface characteristics (e.g., surface roughness) according to the surface treatment method. For example, the surfaces of the first metal film layer 412 and the second metal film layer 413 may include first oxide surface-treated regions 421a and 431a and second oxide surface-treated regions 421b and 431b, and the soft etching treated regions 422 and 432 may be included between the first oxide surface-treated regions 421a and 431a and the second oxide surface-treated regions 421b and 431b. According to various embodiments, the soft etching treated regions 422 and 432 and the oxide surface-treated regions 421a, 421b, 431a, and 431b may have different surface roughnesses.

[0107] According to various embodiments, the surface roughness of the soft etch treated regions 422 and 432 may be lower than the surface roughness of the oxide surface treated regions 421 a , 421 b , 431 a , and 431 b .

[0108] According to various embodiments, the first oxide surface-treated regions 421a and 431a and the second oxide surface-treated regions 421b and 431b may improve the components of the rigid regions R and R′ (eg, Figure 6 The adhesion between the insulating layer 441 and the composite film layer 410 (eg, the metal film layers 412 and 413) and the soft etching treated areas 422 and 432 can improve the components of the flexible area F (eg, Figure 6The adhesion and repeated bending life between the covering adhesive layer 451 and the composite film layer (e.g., the metal film layers 412 and 413) can be improved. For example, compared with the first oxide surface-treated regions 421a and 431a and the second oxide surface-treated regions 421b and 431b, the soft-etched regions 422 and 432 can have a low surface roughness due to a lower etching amount, and therefore, a lower degree of notches, which can improve the repeated bending life. For example, deformation (flow) can occur in the soft-etched regions 422 and 432 (e.g., at or near the boundaries of the rigid regions R and R' and the flexible region F) to reduce the occurrence of cracks.

[0109] According to various embodiments, the metal film layers 412 and 413 may include at least one metal or alloy of Cu, Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr. In some examples, the metal film layers 412 and 413 may each include a copper foil or a copper alloy foil. For example, the copper alloy foil may include Cu; and at least one or more of Ag, Cr, Fe, In, Ni, P, Si, Sn, Te, Ti, Zn, and Zr or a mixture thereof (e.g., 0.01 mass % to 1 mass % of the alloy). According to various embodiments, each thickness of the metal film layers 412 and 413 can be about 6μm to about 36μm; about 6μm to about 34μm; about 6μm to about 32μm; about 6μm to about 30μm; about 6μm to about 28μm; about 6μm to about 25μm; about 6μm to about 10μm; about 6μm to about 8μm; about 7μm to about 36μm; about 9μm to about 36μm; about 12μm to about 36μm; about 15μm to about 36μm; about 18μm to about 36μm; about 20μm to about 36μm; or about 25μm to about 36μm.

[0110] According to various embodiments, the rigid regions R and R' may be formed on at least a portion of at least one surface of the composite film 410, and in some examples, may be formed on at least a portion of both surfaces (e.g., metal thin film layers 412 and 413) of the composite film 410. In some examples, the rigid regions R may be formed on oxide surface-treated regions of the metal thin film layers 412 and 413 in order to improve adhesion between the surfaces of the metal thin film layers 412 and 413 and components (e.g., insulating layer 441) on the lower end of the rigid regions R and reduce the occurrence of via cracks. For example, the rigid regions R and R' may be formed on the first oxide surface-treated regions 421a and 431a and the second oxide surface-treated regions 421b and 431b.

[0111] According to various embodiments, each of the rigid regions R and R' may include a laminate structure 440 including an insulating layer 441, a pattern layer 442, and a photosensitive solder resist (PSR) layer 444. The rigid regions R and R' may be rigid portions having less flexibility or less flexibility than the flexible region F.

[0112] According to various embodiments, the insulating layer 441 may be formed on the oxide surface-treated regions 421a, 431a, 421b, and 431b, and may include a thermosetting resin or a prepreg material (PPG). For example, PPG may be a material in which a liquid synthetic resin is impregnated into a fiber reinforcement (e.g., a reinforcing matrix material), such as carbon fiber or glass fiber. PPG may include, for example, a thermosetting resin (such as a phenol resin or an epoxy resin) and a thermoplastic resin (such as polyether ketone). PPG may include, for example, a unidirectional PPG and a cross PPG. In some examples, the PPG may include a low-flow type PPG or a flowable semi-cured state (B-stage) PPG, and may be cured by a pressurization and heating process in a semi-cured state.

[0113] According to various embodiments, the pattern layer 442 is formed with a via 443 and a conductor pattern layer, the via 443 may be formed in the insulating layer 441 by laser drilling, etc., and electroplating may be performed to form the pattern layer 442 by forming an electroless plating layer 442 on the inner wall surface of the via 443 and / or forming a plating resist pattern on the insulating layer 441. The PSR layer 444 may be a protective layer for protecting components (e.g., the pattern layer 442) of the rigid regions R and R'.

[0114] According to various embodiments, the rigid regions R and R' may be formed in a single region or in a plurality of regions. In some examples, a first rigid region R and a second rigid region R' may be included, and the flexible region F may be located between the first rigid region R and the second rigid region R'. In some examples, the first rigid region R, the flexible region F, the second rigid region R', and the flexible region F may be arranged sequentially.

[0115] According to various embodiments, the flexible region F may be formed on at least a portion of at least one surface of the composite film 410, and in some examples, may be formed on at least a portion of both surfaces of the composite film 410 (e.g., the metal film layers 412 and 413). In some examples, the flexible region F may be formed on the soft-etched regions 422 and 432 with a smaller etching amount than the oxide surface-treated regions of the metal film layers 412 and 413, so as to improve not only the adhesion between the surfaces of the metal film layers 412 and 413 and the components at the lower end of the flexible region F (e.g., the covering adhesive layer 451) but also the bendability. This can stably improve the hinge portion having a repeated bending structure (e.g., Figure 3 The hinge structure 230 of the electronic device 200, or Figure 7a and Figure 7b The repeated bending life of the hinge housing 583 and the hinge assembly 584 of the electronic device 580).

[0116] According to various embodiments, the flexible region F may include a laminate structure 450 including a cover adhesive layer 451 and a cover layer 452. The cover adhesive layer 451 may be formed on the soft etching processed regions 422 and 432, and the cover layer 452 may be formed on the cover adhesive layer 451. The cover layer 452 may be a protective layer to prevent the metal thin film layers 412 and 413 from being damaged due to corrosion or external impact, and the cover layer 452 may include a cover film (e.g., a PI film) including the same component as the base film layer 411, and may be fixed by the cover adhesive layer 451.

[0117] According to various embodiments, some components of the flexible region F may extend to a portion of the rigid regions R and R'. For example, a portion (e.g., an end region) of the adhesive layer 451 and the cover layer 452 of the flexible F may extend to a portion of the rigid regions R and R'. For example, a portion (e.g., an end region) of the adhesive layer 451 and the cover layer 452 of the flexible F may extend to a portion of the rigid regions R and R', and the extended portion may be disposed to be in contact with or spaced apart from some components (e.g., the electroless plating layer 442) of the first rigid region R and the second rigid region R'.

[0118] According to various embodiments, the thickness of each of the cover adhesive layer 451 and the cover layer 452 may be about 7.5 μm to 30 μm; about 7.5 μm to about 25 μm; about 7.5 μm to about 20 μm; about 7.5 μm to about 15 μm; about 7.5 μm to about 12 μm; about 7.5 μm to about 10 μm; about 8 μm to about 30 μm; about 10 μm to about 30 μm; about 13 μm to about 30 μm; about 16 μm to about 30 μm; about 18 μm to about 30 μm; or about 20 μm to about 30 μm. In some examples, the thickness of the cover adhesive layer 451 may be about 10 μm to 30 μm, and the thickness of the cover layer 452 may be about 7.5 μm to 25 μm. For example, the thickness of the cover adhesive layer 451 and the cover layer 452 may be applied to improve the protection function and flexibility.

[0119] Figure 7a is a perspective view illustrating a state in which an RFPCB is disposed between a hinge housing and a hinge assembly of a foldable electronic device according to various embodiments.

[0120] Figure 7bis a cross-sectional view schematically illustrating a state in which an RFPCB is disposed between a hinge housing and a hinge assembly of a foldable electronic device according to various embodiments.

[0121] Reference Figure 7a and Figure 7b According to various embodiments, a foldable electronic device 580 (eg, Figures 2 to 4a and Figure 4b The electronic device 200 may include a composite film (eg, Figure 5 Composite film 300) or RFPCB (e.g., Figure 6 RFPCB400). A foldable electronic device 580 (e.g., Figures 2 to 4a and Figure 4b The electronic device 200 may include a foldable display (eg, Figures 2 to 4a and Figure 4b Foldable display 250).

[0122] According to various embodiments, a foldable electronic device 580 (eg, Figures 2 to 4a and Figure 4b The electronic device 200 may include a first component, a second component, and a composite film electrically connecting the first component and the second component (eg, Figure 5 Composite film 300) or RFPCB (e.g., Figure 6 RFPCB 400).

[0123] According to various embodiments, a foldable electronic device 580 (eg, Figures 2 to 4a and Figure 4b The electronic device 200 may include a first housing 581 (eg, Figures 2 to 4a and Figure 4b The first shell structure 210), the second shell 582 (for example, Figures 2 to 4a and Figure 4b The second housing structure 220 of the present invention includes a hinge housing 583, a hinge assembly 584, and an RFPCB 585. According to various embodiments, the RFPCB 585 may include Figure 5 Composite membrane 300 or Figure 6 RFPCB 400.

[0124] According to various embodiments, the hinge assembly 584 may connect the first housing 581 and the second housing 582 to be foldable and expandable, and the RFPCB 585 (eg, including Figure 5 Composite membrane 300 or Figure 6The RFPCB 400 of the foldable electronic device 580 may be a connection device for electrically connecting a first component provided in the first housing 581 and a second component provided in the second housing 582. According to various embodiments, during the folding and unfolding operation of the foldable electronic device 580, the RFPCB 585 may transmit signals between the first component and the second component and may be accommodated in the hinge housing 583.

[0125] Figure 8 is a flow chart of operations for making a composite membrane according to various embodiments.

[0126] refer to Figure 8 According to various embodiments, a composite film (e.g., Figure 5 The method of the composite film 300) may include: an operation 610 of preparing a composite film base material having a base material and a metal thin film layer formed on the base material; and an operation 620 of processing a surface of the metal thin film layer.

[0127] According to various embodiments, in operation 610 of preparing a composite film base material, the composite film base material may include a base film layer (eg, Figure 5 The base film layer 310) and the base film layer at least partially formed on the base film layer (for example, Figure 5 The metal thin film layers (eg, Figure 5 In some examples, the composite film base material may be FCCL.

[0128] According to various embodiments, operation 620 of treating the surface of the metal thin film layer includes forming a region having two or more surface characteristics by surface treatment, and for example, a soft etching process and an oxide treatment process may be used. Wet etching, flash etching, or a fast etching method may be used for the soft etching process. According to various embodiments, in wet etching, a soft etchant containing an inorganic acid or an organic acid may be used. For example, a persulfate / sulfuric acid type (e.g., H 2 O 2 and H 2 SO 4 ), sodium persulfate / sulfuric acid type (e.g., Na 2 S 2 O 8 and H 2 SO 4) to perform the soft etching process, but is not limited thereto. According to various embodiments, the surfaces of the metal film layers 320 and 330 other than the areas subjected to the surface treatment by the soft etching process may be optionally subjected to an oxide treatment, and may be subjected to the oxide surface treatment using a brown oxide reactant or a black oxide reactant. In some examples, a brown oxide reactant may be used, for example, a brown oxide reactant may include peroxide (H 2 O 2 In some examples, a black oxide reactant may be used. For example, the black oxide reactant may include an oxidant and an alkali. The oxidant may include NaClO, NaClO 2 、NaClO 3 、KClO、KClO 2 and KClO 3 , and the base may include sodium hydroxide, potassium hydroxide, barium hydroxide, ammonium hydroxide, tetramethylammonium hydroxide, or tetraethylammonium hydroxide as a hydroxide, but is not limited thereto.

[0129] According to various embodiments, the method may further include an operation of patterning the metal film layer of the composite film substrate material or an operation of forming a pattern layer on the metal film layer of the composite film substrate material. This may be performed before and / or after operation 620 of processing the surface of the metal film layer. In some examples, this may be performed before operation 620 of processing the surface of the metal film layer, and the characteristics of the pattern surface (e.g., surface roughness) may be controlled by surface treatment.

[0130] Fig. 9 is a flow chart of operations for manufacturing an RF PCB according to various embodiments.

[0131] Reference Fig. 9 According to various embodiments, manufacturing an RFPCB (e.g., Figure 6 The method of RFPCB 400) may include: operation 710 of preparing a composite film base material; operation 720 of patterning a metal film layer; operation 730 of forming a soft etched area on at least a portion of the patterned metal film layer; operation 740 of forming a flexible area in the soft etched area; operation 750 of forming an oxide surface treated area on at least a portion of the metal film layer; and operation 760 of forming a rigid area in the oxide surface treated area.

[0132] According to various embodiments, the operation 710 of preparing the composite film substrate material can be the same as described above with reference to Figure 8 The operation 610 of preparing a composite membrane base material is the same or similar to that described in the flowchart of the composite membrane.

[0133] According to various embodiments, in operation 720 of patterning the metal thin film layer, a patterning process of a metal thin film known in the technical field of the present disclosure may be used and will not be described in detail herein.

[0134] According to various embodiments, the operation 730 of forming the soft-etched region and the operation 750 of forming the oxide surface-treated region may be respectively the same as those described above with reference to Figure 8 The soft etching process described in the flow chart of the composite film is the same or similar to the oxide surface treatment process.

[0135] According to various embodiments, operation 740 of forming the flexible region may include laminating and roll-coating an adhesive layer (e.g., Figure 6 of the covering adhesive layer 451) and the covering layer (e.g., Figure 6 covering layer 452).

[0136] According to various embodiments, operation 760 of forming a rigid region may include the following operations: forming an insulating layer (eg, Figure 6 Insulating layer 441); in the insulating layer (for example, Figure 6 A via hole (eg, Figure 6 forming a conductor pattern (eg, Figure 6 and forming a protective layer (eg, Figure 6 Each operation may be performed using methods such as coating, printing, drilling, patterning, etching, and plating (eg, electroless plating), which are not specifically described herein.

[0137] According to various embodiments, an RFPCB (e.g., Figure 6 The bending level of the RFPCB 400) is evaluated. For example, sample 1 is obtained by performing an oxide surface treatment (e.g., brown oxide treatment, etc.) on the entire surface, and sample 2 is obtained by performing an oxide surface treatment (e.g., brown oxide treatment, etc.) and a soft etching treatment. Sample 1 and sample 2 each include an FCCL having a base PI film and a copper foil of about 12 μm. Each of sample 1 and sample 2 is used to manufacture an RFPCB (e.g., Figure 6 RFPCB 400). The following [Table 1] shows the bending life evaluation results of the RFPCB to which the FCCL of Sample 1 and Sample 2 are applied. Referring to [Table 1], it can be confirmed that the RFPCB (Sample 2-1) according to the embodiment of the present disclosure has a bending life increased by about 2 times or more compared with the PCB (Sample 1-1) according to the comparative example in which the entire surface is subjected to oxide treatment during the heterogeneous pretreatment of the inner layer copper foil.

[0138] [Table 1]

[0139] Process conditions for evaluating bending life: ±90 degrees (º) and performed 30,000 times (0.38R, load of 300G, 60 times / min).

[0140] According to various embodiments, the composite film (300) may include a base film layer (310); a first metal film layer (320) formed on one surface of the base film layer (310); and a second metal film layer (330) formed on an opposite surface. The first metal film layer (320) and the second metal film layer (330) may include soft etching treated regions (322, 332) and oxide surface treated regions (321a, 321b, 331a, 331b), and the soft etching treated regions (322, 332) and the oxide surface treated regions (321a, 321b, 331a, 331b) may have different surface roughnesses.

[0141] According to various embodiments, the surface roughness of the soft etch treated region ( 322 , 332 ) may be lower than the surface roughness of the oxide surface treated region ( 321 a , 321 b , 331 a , 331 b ).

[0142] According to various embodiments, the oxide surface treated regions ( 321 a , 321 b , 331 a , 331 b ) may be formed by a brown oxide operation or a black oxide operation.

[0143] According to various embodiments, the soft etch processed region ( 322 , 332 ) may be formed by wet etching, flash etching, or rapid etching operations.

[0144] According to various embodiments, the first metal thin film layer (320) and the second metal thin film layer (330) may each include a copper foil or a copper alloy foil.

[0145] According to various embodiments, the base film layer ( 310 ) may have a thickness of about 7.5 μm to about 25 μm, and the first metal thin film layer ( 320 ) and the second metal thin film layer ( 330 ) may have a thickness of about 6 μm to about 36 μm, respectively.

[0146] According to various embodiments, a first oxide surface-treated region (321a, 331a) and a second oxide surface-treated region (321b, 331b) may be included, and a soft-etched region (322, 332) may be included between the first oxide surface-treated region (321a, 331a) and the second oxide surface-treated region (321b, 331b).

[0147] According to various embodiments, an RFPCB may include a composite film (410); a flexible region (F) formed on at least a portion of at least one surface of the composite film (410); and a rigid region (R, R') formed on at least a portion of at least one surface of the composite film (410). The composite film (410) may include a base film layer (411); and a first metal film layer (412) formed on one surface of the base film layer (411); and a second metal film layer (413) formed on an opposite surface, the first metal film layer (412) and the second metal film layer (413) may include soft etching treated regions (422, 432) and oxide surface treated regions, and the soft etching treated regions (422, 432) and the oxide surface treated regions (421a, 431a, 421b, 431b) may have different surface roughnesses.

[0148] According to various embodiments, the flexible region (F) may be formed on the soft etch treated region ( 422 , 432 ), and the rigid region (R, R′) may be formed on the oxide surface treated region ( 421 a , 431 a , 421 b , 431 b ).

[0149] According to various embodiments, a portion of the component formed on the flexible region (F) may extend to a portion of the rigid region (R, R′).

[0150] According to various embodiments, the flexible region (F) may include a cover adhesive layer (451) formed on the soft etch processed region (422, 432); and a cover layer (452) formed on the cover adhesive layer (451).

[0151] According to various embodiments, the cover adhesive layer (451), the cover layer (452), or a portion of the cover adhesive layer and the cover layer may extend to a portion of the rigid region (R, R').

[0152] According to various embodiments, the cover layer ( 452 ) and the cover adhesive layer ( 451 ) may have a thickness of about 7.5 μm to about 30 μm, respectively.

[0153] According to various embodiments, the surface roughness of the soft etch treated region ( 422 , 432 ) may be lower than the surface roughness of the oxide surface treated region ( 421 a , 431 a , 421 b , 431 b ).

[0154] According to various embodiments, the oxide surface treated regions ( 421 a , 431 a , 421 b , 431 b ) may be formed by a brown oxide operation or a black oxide operation.

[0155] According to various embodiments, the soft etch processed region ( 422 , 432 ) may be formed by wet etching, flash etching, or a rapid etching operation.

[0156] According to various embodiments, circuit patterns may be formed on the first metal thin film layer 412 and the second metal thin film layer 413 .

[0157] According to various embodiments, an electronic device may include: a flexible display; and the composite film (300) of the present disclosure or the RFPCB (400) of the present disclosure.

[0158] According to various embodiments, the composite film 300 or the RFPCB 400 may be applied to a hinge portion of an electronic device.

[0159] According to various embodiments, an electronic device may include a foldable display.

[0160] The electronic device according to various embodiments may be one of various types of electronic devices. The electronic device may include, for example, a portable communication device (e.g., a smart phone), a computer device, a portable multimedia device, a portable medical device, a camera, a wearable device, or a household appliance device. According to an embodiment of the present disclosure, the electronic device is not limited to those described above.

[0161] It should be understood that the various embodiments of the present disclosure and the terms used therein are not intended to limit the technical features set forth herein to specific embodiments, and include various changes, equivalents or replacements of the corresponding embodiments. In conjunction with the description of the accompanying drawings, the same reference numerals may be used for similar or related parts. It should be understood that, unless otherwise clearly stated in the relevant context, the singular form of the noun corresponding to the project may include one or more things. As used herein, each of "A or B", "at least one of A and B", "at least one of A or B", "A, B or C", "at least one of A, B and C" and "at least one of A, B or C" may include any one of the items listed together in a corresponding phrase, or all possible combinations thereof. Terms such as "1st", "2nd" or "first" or "second" may be used simply to distinguish components from other components discussed, and do not limit components in other aspects (e.g., importance or order). It should be understood that if a component (e.g., a first component) is referred to as being "coupled with another component (e.g., a second component)", "coupled to" another component (e.g., the second component), "connected with" or "connected to" another component (e.g., the second component), with or without the term "operably" or "communicatively", the component may be coupled to the other component directly (e.g., by wire), wirelessly, or via a third component.

[0162] As used in conjunction with embodiments of the present disclosure, the term "module" may include units implemented in hardware, software, or firmware, and may be used interchangeably with other terms, such as "logic," "logic block," "portion," or "circuit." A module may be a single integrated component, or a minimum unit or portion thereof, suitable for performing one or more functions. For example, according to an embodiment, a module may be implemented in the form of an application specific integrated circuit (ASIC).

[0163] The various embodiments described herein may be implemented as software (e.g., program 140) including one or more instructions stored in a storage medium (e.g., internal memory 136 or external memory 138) readable by a machine (e.g., electronic device 101). For example, a processor (e.g., processor 120) of a machine (e.g., electronic device 101) may call at least one of the one or more instructions stored in the storage medium and execute it. This allows the machine to be operated to perform at least one function according to at least one instruction called. One or more instructions may include code generated by a compiler or code executable by an interpreter. The machine-readable storage medium may be provided in the form of a non-transitory storage medium. Here, the term "non-transitory" simply means that the storage medium is a tangible device and does not include signals (e.g., electromagnetic waves), but the term does not distinguish between data being semi-permanently stored in the storage medium and data being temporarily stored in the storage medium.

[0164] According to an embodiment, the method according to various embodiments of the present disclosure may be included and provided in a computer program product. The computer program product may be traded between a seller and a buyer as a commodity. The computer program product may be distributed in the form of a machine-readable storage medium (e.g., a compact disc read-only memory (CD-ROM)), or via an application store (e.g., PlayStore). TM ) online distribution (e.g., download or upload), or directly between two user devices (e.g., smartphones). If distributed online, at least a portion of the computer program product may be temporarily generated or at least temporarily stored in a machine-readable storage medium (such as a memory of a manufacturer's server, an application store's server, or a relay server).

[0165] According to various embodiments, each component (e.g., module or program) in the above-mentioned components may include a single entity or multiple entities, and some of the multiple entities may be individually arranged in different components. According to an embodiment, one or more of the above-mentioned components may be omitted, or one or more other components may be added. Alternatively or additionally, multiple components (e.g., module or program) may be integrated into a single component. In this case, the integrated component may perform one or more functions of a corresponding component in the multiple components in the same or similar manner as performed by each component in the multiple components before integration. According to an embodiment, the operations performed by a module, program or another component may be performed sequentially, in parallel, repeatedly or heuristically, or one or more operations may be performed or omitted in different orders, or one or more other operations may be added.

Claims

1. A composite film comprising: Base film layer; A first metal film layer is formed on one surface of the base film layer; as well as A second metal film layer is formed on the opposite surface, The first metal film layer and the second metal film layer include a soft etching treated area and an oxide surface treated area, and The soft etching treated region and the oxide surface treated region have different surface roughnesses.

2. The composite film according to claim 1, wherein The surface roughness of the soft-etching treated region is lower than the surface roughness of the oxide-surface treated region.

3. The composite membrane according to claim 1 , wherein: The oxide surface treated area is formed by a brown oxide operation or a black oxide operation, and The soft etched area is formed by wet etching, flash etching or flash etching operation.

4. The composite membrane according to claim 1, wherein The first metal thin film layer and the second metal thin film layer each include copper foil or copper alloy foil.

5. The composite membrane according to claim 1, wherein The base film layer has a thickness of 7.5 μm to 25 μm, and The first metal thin film layer and the second metal thin film layer have a thickness of 6 μm to 36 μm respectively.

6. The composite membrane according to claim 1, wherein A first oxide surface treated region and a second oxide surface treated region are included, and The soft etching treated region is included between the first oxide surface treated region and the second oxide surface treated region.

7. A rigid flexible printed circuit board (RFPCB), comprising: Composite membrane; a flexible region formed on at least a portion of at least one surface of the composite film; as well as a rigid region formed on at least a portion of at least one surface of the composite film, Wherein, the composite film comprises: Base film layer; A first metal thin film layer is formed on one surface of the base film layer; and A second metal film layer is formed on the opposite surface, The first metal film layer and the second metal film layer include a soft etching treated area and an oxide surface treated area The soft etching treated region and the oxide surface treated region have different surface roughnesses.

8. The RFPCB according to claim 7, wherein: The flexible region is formed on the soft etching processed region, and The rigid region is formed on the oxide surface treated region.

9. The RFPCB according to one of claims 7 and 8, wherein: A portion of the member formed on the flexible region extends to a portion of the rigid region.

10. The RFPCB according to one of claims 7 to 9, wherein: The flexible region comprises: a covering adhesive layer formed on the soft etching processed area; and a covering layer formed on the covering adhesive layer, The cover adhesive layer, the cover layer, or a portion of the cover adhesive layer and the cover layer extends to a portion of the rigid region.

11. The RFPCB according to one of claims 7 to 10, wherein: The cover layer and the cover adhesive layer each have a thickness of 7.5 μm to 30 μm.

12. The RFPCB according to one of claims 7 to 11, wherein: The surface roughness of the soft-etching treated region is lower than the surface roughness of the oxide-surface treated region.

13. The RFPCB according to one of claims 7 to 12, wherein: The oxide surface treated area is formed by a brown oxide operation or a black oxide operation, and The soft etched area is formed by wet etching, flash etching or flash etching operation.

14. The RFPCB according to one of claims 7 to 13, wherein: A circuit pattern is formed on the first metal thin film layer and the second metal thin film layer.

15. An electronic device comprising: Flexible displays; as well as A composite film according to one of claims 1 to 6 or a rigid flexible printed circuit board (RFPCB) according to one of claims 7 to 14.

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