Flexible circuit plate, circuit board assembly, temperature detection apparatus, and electronic device

Abstract

Embodiments of the present application relate to the field of electronics, and provide a flexible circuit plate, a circuit board assembly, a temperature detection apparatus, and an electronic device, used for accurately detecting in real time the temperature of a position to be detected. A thermistor is integrated inside the flexible circuit board, and the change in the temperature of the position where the thermistor is located is detected in light of the change in the resistance value of the thermistor with the temperature, so as to achieve the purpose of detecting the change in the temperature of a wiring inside the flexible circuit board, without the need for additional processing units. The thermistor can be flexibly arranged to detect in real time the temperature of various positions to be detected. The temperature can also be detected by using a temperature detection apparatus serving as an independent apparatus, a heat source to be detected is not directly connected to the temperature detection apparatus, and a thermistor in the temperature detection apparatus may be close to any heat source to be detected (an apparatus, a pad, a wiring, a component, etc.), so as to detect the temperature of said heat source, has flexible arrangement, and does not affect the power consumption of said heat source.

Description

Flexible circuit boards, circuit board assemblies, temperature sensing devices, electronic equipment

[0001] This application claims priority to Chinese patent application filed on July 22, 2024, with application number 202410992520.9 and title "Flexible Circuit Board, Circuit Board Assembly, Temperature Detection Device, Electronic Equipment", the entire contents of which are incorporated herein by reference. Technical Field

[0002] This application relates to the field of electronics, and more particularly to a flexible circuit board, a circuit board assembly, a temperature sensing device, and an electronic device. Background Technology

[0003] With the development of electronic technology, the functions of electronic devices are becoming increasingly rich and comprehensive. The processing power of functional modules such as chips and power devices in electronic devices is constantly improving, and power consumption is also increasing, leading to excessively high local temperatures in electronic devices. If not addressed in time, this may affect the performance of electronic devices, even causing damage or safety accidents.

[0004] Therefore, if the temperature of high-heat-generating locations that need to be monitored in electronic products can be detected in real time and accurately, reasonable thermal management and product thermal fatigue life prediction can be effectively carried out. Summary of the Invention

[0005] This application provides a flexible circuit board, a circuit board assembly, a temperature sensing device, and an electronic device for real-time and accurate detection of the temperature at the desired detection location.

[0006] A first aspect of this application provides a flexible circuit board, comprising a first flexible dielectric layer and a second flexible dielectric layer stacked together; a first pin, a second pin, a third pin, and a fourth pin, all of which are exposed on the surface of the flexible circuit board; a first trace and a first thermistor disposed between the first and second flexible dielectric layers; the first thermistor coupled between the first pin and the second pin, the first thermistor being spaced apart from the first trace, and the first thermistor being a thin-film resistor; and the first trace coupled between the third pin and the fourth pin.

[0007] The flexible circuit board provided in this application embodiment integrates a first thermistor inside the flexible circuit board. The first thermistor is spaced apart from the first trace. By observing the change in the resistance of the first thermistor with temperature, the temperature change at the location of the first thermistor is detected, thereby achieving the purpose of detecting the temperature change of the first trace inside the flexible circuit board, without the need for additional temperature detection devices. The first thermistor can be flexibly arranged to detect the temperature of the first trace under test in real time.

[0008] In one possible implementation, the flexible circuit board includes a second trace, on which the first thermistor is located, and the first thermistor is coupled between the first pin and the second pin via the second trace.

[0009] In one possible implementation, the flexible circuit board includes multiple first thermistors, which are connected in series between a first pin and a second pin. The multiple first thermistors are arranged at intervals, which improves the accuracy of test results and allows monitoring of temperature changes at the portion of the first trace adjacent to each first thermistor, facilitating the location of specific heat generation points on the first trace.

[0010] In one possible implementation, the spacing between adjacent first thermistors is d, where 0.05mm ≤ d ≤ 2mm. By setting the spacing between adjacent first thermistors within the range of 0.05mm-2mm, the processing error of the first thermistors can be reduced, and the accuracy of the first thermistors can be improved.

[0011] In one possible implementation, the first thermistor is directly coupled to the first and second pins. This allows for the detection of the temperature along the entire first trace that is spaced apart (e.g., adjacent) from the first thermistor, providing a wide detection range.

[0012] In one possible implementation, the first trace and the first thermistor are disposed on the same layer. This reduces the number of separator layers between the first trace and the first thermistor, decreases temperature loss during the transfer of temperature from the first trace to the first thermistor, and improves the detection accuracy of the first thermistor.

[0013] In one possible implementation, the flexible circuit board further includes a first resistor disposed on the side of the second flexible dielectric layer away from the first thermistor; the flexible circuit board also includes a fifth pin exposed on the surface of the flexible circuit board, and the first resistor is coupled between the fifth pin and the first pin, wherein the first resistor is a thin-film resistor. By setting the first resistor in series with the first thermistor, it is equivalent to setting a pull-up resistor, which can increase the series resistance of the first resistor and the first thermistor, thereby reducing the power consumption of the detection circuit.

[0014] In one possible implementation, the flexible circuit board also includes a capacitor, which is connected in parallel with the first thermistor between the first and second pins. By setting the capacitor in parallel with the first thermistor, a filter can be formed to improve the temperature detection accuracy.

[0015] In one possible implementation, the flexible circuit board further includes a sixth pin and a Wheatstone bridge; the sixth pin is exposed on the surface of the flexible circuit board; the Wheatstone bridge includes a first input terminal, a second input terminal, a first output terminal, a second output terminal, a first thermistor, and multiple second resistors; the first and second input terminals are coupled to the sixth pin, the first output terminal is coupled to the first pin, the second output terminal is coupled to the second pin, and the second resistors are thin-film resistors. By using a Wheatstone bridge to detect temperature changes, the change in resistance of the first thermistor caused by temperature changes can be amplified, thereby improving the accuracy of temperature detection with the same length of the first thermistor. At the same detection accuracy, the length of the first thermistor can be reduced.

[0016] In one possible implementation, the flexible circuit board further includes a third resistor and a seventh pin; the seventh pin is exposed on the surface of the flexible circuit board; the third resistor is coupled between the seventh pin and the first input terminal. The third resistor is connected in series with a Wheatstone bridge, acting as a pull-up resistor, which can reduce the overall power consumption of the temperature sensing device.

[0017] A second aspect of the embodiments of this application provides a circuit board assembly, the circuit board assembly including a rigid circuit board, a flexible circuit board and a processing unit, the flexible circuit board including any of the flexible circuit boards in the first aspect; a first pin is connected to the rigid circuit board, and the processing unit is coupled to the first pin.

[0018] In one possible implementation, the circuit board assembly also includes a first resistor coupled to a first pin. The first resistor, serving as a pull-up resistor, can also be externally connected to a rigid circuit board, eliminating the need for a separate pull-up resistor in the flexible circuit board, thus reducing the manufacturing complexity of the flexible circuit board.

[0019] In one possible implementation, the circuit board assembly also includes a capacitor, which is coupled in parallel with the first thermistor. The capacitor, serving as a filter capacitor, can also be externally connected to a rigid circuit board, eliminating the need to include it in the flexible circuit board and thus reducing the manufacturing complexity of the flexible circuit board.

[0020] In one possible implementation, the circuit board assembly also includes a third resistor coupled to the first input terminal. The third resistor, serving as a pull-up resistor, can also be externally connected to a rigid circuit board, eliminating the need for a separate pull-up resistor in the flexible circuit board and thus reducing the manufacturing complexity of the flexible circuit board.

[0021] A third aspect of the embodiments of this application provides an electronic device, the electronic device including a circuit board assembly and a housing, the circuit board assembly being disposed within the housing, and the circuit board assembly including any of the circuit board assemblies of the second aspect.

[0022] A fourth aspect of this application provides a temperature sensing device, comprising: a first dielectric layer and a second dielectric layer stacked together; a first pin and a second pin exposed on the surface of the temperature sensing device; a first conductor layer disposed between the first dielectric layer and the second dielectric layer; the first conductor layer including a first thermistor coupled between the first pin and the second pin, wherein the first thermistor is a thin-film resistor.

[0023] The temperature detection device provided in this application embodiment is an independent device. The heat source to be tested is not directly connected to the temperature detection device. The first thermistor in the temperature detection device can be close to any heat source to be tested (device, pad, trace, component, etc.) to detect the temperature of the heat source to be tested. The layout is flexible and does not affect the power consumption of the heat source to be tested.

[0024] In one possible implementation, the first conductor layer includes a plurality of first thermistors, which are connected in series between the first pin and the second pin. Connecting multiple first thermistors in series can improve the detection accuracy of the temperature sensing device.

[0025] In one possible implementation, the spacing between adjacent first thermistors is d, where 0.05mm ≤ d ≤ 2mm. By setting the spacing between adjacent first thermistors within the range of 0.05mm-2mm, the processing error of the first thermistors can be reduced, and the accuracy of the first thermistors can be improved.

[0026] In one possible implementation, the temperature sensing device further includes a second conductor layer disposed on the side of the second dielectric layer away from the first conductor layer; the second conductor layer includes a first resistor; the temperature sensing device also includes a fifth pin; the first resistor is coupled between the fifth pin and the first pin, and the first resistor is a thin-film resistor. By setting a first resistor in series with the first thermistor, it is equivalent to setting a pull-up resistor, which can increase the series resistance of the first resistor and the first thermistor, thereby reducing the power consumption of the sensing circuit.

[0027] In one possible implementation, the temperature sensing device further includes a capacitor, which is connected in parallel with the first thermistor between the first and second pins. By configuring the capacitor in parallel with the first thermistor, a filter can be formed to improve the accuracy of temperature sensing.

[0028] In one possible implementation, the temperature sensing device further includes a third conductor layer and a Wheatstone bridge. The third conductor layer is disposed on the side of the second dielectric layer away from the first conductor layer. The temperature sensing device also includes a sixth pin exposed on the surface of the temperature sensing device. The Wheatstone bridge includes a first input terminal, a second input terminal, a first output terminal, a second output terminal, a first thermistor, and multiple second resistors. The first and second input terminals are coupled to the sixth pin, the first output terminal is coupled to the first pin, and the second output terminal is coupled to the second pin. The second resistors are located in either the first or third conductor layer and are thin-film resistors. By using a Wheatstone bridge to detect temperature changes, the change in resistance of the first thermistor caused by temperature changes can be amplified. With the same length of the first thermistor, the accuracy of temperature detection can be improved. For the same detection accuracy, the length of the first thermistor can be reduced.

[0029] In one possible implementation, the temperature sensing device further includes a third resistor and a seventh pin; the seventh pin is exposed on the surface of the temperature sensing device; the third resistor is coupled between the seventh pin and the first input terminal. The third resistor is connected in series with a Wheatstone bridge, acting as a pull-up resistor, which can reduce the overall power consumption of the temperature sensing device.

[0030] In one possible implementation, the first dielectric layer includes a first opening, which is offset from the first thermistor. By providing the first opening in the first dielectric layer, the thermal barrier effect of the dielectric layer can be reduced, improving the temperature sensitivity of the first thermistor and thus enhancing the temperature detection performance.

[0031] In one possible implementation, the second dielectric layer includes a second opening, which is offset from the first thermistor. By providing a second opening on the second dielectric layer, the thermal barrier effect of the dielectric layer can be reduced, improving the temperature sensitivity of the first thermistor and thus enhancing the temperature detection performance.

[0032] In one possible implementation, the first conductor layer further includes a second thermistor, an eighth pin, and a ninth pin; the second thermistor is spaced apart from the first thermistor, the eighth and ninth pins are exposed on the surface of the temperature sensing device, and the second thermistor is coupled between the eighth and ninth pins; the second thermistor is a thin-film resistor. This is equivalent to setting multiple detection circuits in the temperature sensing device, which operate independently, thereby improving the accuracy of the temperature sensing device.

[0033] A fifth aspect of the present application provides an electronic device, which includes: a temperature detection device, a heat source to be measured, and a processing unit. The temperature detection device and the heat source to be measured are arranged adjacent to each other, and the processing unit is coupled to a first pin and a second pin. The temperature detection device includes any one of the temperature detection devices in the fourth aspect.

[0034] In the electronic device provided in this application embodiment, the temperature detection device can be disposed adjacent to any heat source to be measured in the electronic device (e.g., in direct contact or contact). The heat source to be measured can be a heat source under test; it can also be an assembly assembled with the heat source under test. After assembling the heat source under test, the temperature detection device is placed adjacent to the heat source under test. When the temperature of the heat source under test changes, it causes a change in the resistance of the temperature detection device, thereby obtaining a change in circuit voltage, and ultimately obtaining the temperature change. This enables real-time detection of temperature changes in the structure under test, offering flexible settings and a wide range of applications.

[0035] In one possible implementation, the temperature sensing device is in contact with the heat source to be measured.

[0036] In one possible implementation, the electronic device also includes a circuit board connected to the first pin and the second pin.

[0037] A sixth aspect of this application provides a method for fabricating a flexible circuit board. The method includes: forming a second flexible dielectric layer; forming a first trace, a first thermistor, a first pin, a second pin, a third pin, and a fourth pin on one side of the second flexible dielectric layer; the first trace and the first thermistor are spaced apart, the first thermistor is coupled between the first pin and the second pin, and the first thermistor is a thin-film resistor; the first trace is coupled between the third pin and the fourth pin. The first flexible dielectric layer is formed on the side of the first trace and the first thermistor away from the second flexible dielectric layer; the first pin and the second pin are exposed on the surface of the flexible circuit board.

[0038] In one possible implementation, forming the first trace and the first thermistor includes: sequentially forming a thermistor film and a conductive film on one side of the second flexible dielectric layer; patterning the conductive film and the thermistor film to form a first stacked pattern and a second stacked pattern; the stacked pattern of the first conductive film and the thermistor film serves as the first trace; and patterning the conductive film in the second stacked pattern to expose a portion of the thermistor film as the first thermistor.

[0039] In one possible implementation, patterning the conductive film and the thermistor film includes: patterning the conductive film and the thermistor film using exposure, development, and acid etching processes.

[0040] In one possible implementation, patterning the conductive film in the second stack pattern includes: patterning the conductive film in the second stack pattern using an exposure, development, and alkaline etching process.

[0041] A seventh aspect of this application provides a method for fabricating a temperature sensing device. The method includes: forming a second dielectric layer; forming a first conductor layer, a first pin, and a second pin on one side of the second dielectric layer, wherein the first conductor layer includes a first thermistor coupled between the first pin and the second pin, and the first thermistor is a thin-film resistor; forming the first dielectric layer on the side of the first conductor layer away from the second dielectric layer; and exposing the first pin and the second pin on the surface of the temperature sensing device.

[0042] In one possible implementation, forming the first conductor layer includes: sequentially forming a thermistor film and a conductive film on one side of the second dielectric layer; patterning the conductive film and the thermistor film to form a stacked pattern; and patterning the conductive film in the stacked pattern to expose a portion of the thermistor film as the first thermistor.

[0043] In one possible implementation, patterning the conductive film and the thermistor film includes: patterning the conductive film and the thermistor film using exposure, development, and acid etching processes.

[0044] In one possible implementation, patterning the conductive film in the stacked pattern includes: patterning the conductive film in the stacked pattern using exposure, development, and alkaline etching processes. Attached Figure Description

[0045] Figure 1 is an architectural diagram of an electronic device provided in an embodiment of this application;

[0046] Figure 2 is a schematic diagram of a temperature detection scheme provided in an embodiment of this application;

[0047] Figures 3A-5 are schematic diagrams of the structure of a flexible circuit board provided in an embodiment of this application;

[0048] Figure 6A is a topological schematic diagram of a detection circuit provided in an embodiment of this application;

[0049] Figure 6B is a cross-sectional view of a flexible circuit board provided in an embodiment of this application;

[0050] Figure 6C is a topological schematic diagram of a detection circuit provided in an embodiment of this application;

[0051] Figure 7A is a topological schematic diagram of a detection circuit provided in an embodiment of this application;

[0052] Figure 7B is a cross-sectional view of a flexible circuit board provided in an embodiment of this application;

[0053] Figure 7C is a topological schematic diagram of a detection circuit provided in an embodiment of this application;

[0054] Figure 7D is a cross-sectional view of a flexible circuit board provided in an embodiment of this application;

[0055] Figures 8A and 8B are schematic diagrams of a circuit board assembly provided in an embodiment of this application;

[0056] Figures 8C and 8D are schematic diagrams of another circuit board assembly provided in an embodiment of this application;

[0057] Figures 9A-9C are schematic diagrams of the topology of a detection circuit provided in an embodiment of this application;

[0058] Figure 10A is a schematic diagram of another circuit board assembly provided in an embodiment of this application;

[0059] Figure 10B is a schematic diagram of the topology of another detection circuit provided in an embodiment of this application;

[0060] Figure 11 is a schematic diagram of the structure of an electronic device provided in an embodiment of this application;

[0061] Figure 12 is a schematic diagram of the display interface of an electronic device provided in an embodiment of this application;

[0062] Figure 13 is a flowchart illustrating the fabrication process of a flexible circuit board according to an embodiment of this application;

[0063] Figures 14A-14D are schematic diagrams illustrating the fabrication process of a flexible circuit board according to an embodiment of this application;

[0064] Figure 15 is a schematic diagram of the structure of a temperature detection device provided in an embodiment of this application;

[0065] Figure 16 is a schematic diagram of another temperature detection device provided in an embodiment of this application;

[0066] Figures 17A and 17B are schematic diagrams of another temperature detection device provided in the embodiments of this application;

[0067] Figure 18 is a schematic diagram of another temperature detection device provided in an embodiment of this application;

[0068] Figure 19 is a schematic diagram of another temperature detection device provided in an embodiment of this application;

[0069] Figures 20A and 20B are schematic diagrams of another temperature detection device provided in the embodiments of this application;

[0070] Figure 21 is a schematic diagram of another temperature detection device provided in an embodiment of this application;

[0071] Figure 22 is a partial schematic diagram of an electronic device provided in an embodiment of this application;

[0072] Figure 23 is a partial schematic diagram of another electronic device provided in an embodiment of this application;

[0073] Figure 24 is a partial schematic diagram of another electronic device provided in an embodiment of this application;

[0074] Figure 25 is a schematic diagram of the fabrication process of a temperature detection device provided in an embodiment of this application. Detailed Implementation

[0075] The technical solutions of the embodiments of this application will be described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments.

[0076] Hereinafter, the terms "second," "first," etc., are used for descriptive convenience only and should not be construed as indicating or implying relative importance or implicitly specifying the number of indicated technical features. Therefore, a feature defined with "second," "first," etc., may explicitly or implicitly include one or more of that feature. In the description of this application, unless otherwise stated, "a plurality of" means two or more.

[0077] Furthermore, in the embodiments of this application, directional terms such as "upper," "lower," "left," and "right" may be defined relative to the orientation in which the components are schematically placed in the accompanying drawings. It should be understood that these directional terms can be relative concepts, used for relative description and clarification, and can change accordingly based on the orientation of the components in the accompanying drawings.

[0078] In the embodiments of this application, unless otherwise explicitly specified and limited, the term "connection" should be interpreted broadly. For example, "connection" can be a fixed connection, a detachable connection, or an integral part; it can be a direct connection or an indirect connection through an intermediate medium. Furthermore, the term "coupled connection" can be a direct electrical connection or an indirect electrical connection through an intermediate medium. The term "contact" can be direct contact or indirect contact through an intermediate medium.

[0079] In this embodiment of the application, "and / or" describes the relationship between associated objects, indicating that three relationships can exist. For example, A and / or B can represent: A existing alone, A and B existing simultaneously, or B existing alone, where A and B can be singular or plural. The character " / " generally indicates that the preceding and following associated objects have an "or" relationship.

[0080] This application provides an electronic device, which may be, for example, a foldable electronic device. The electronic device may be, for example, a consumer electronics product, a home electronics product, an in-vehicle electronics product, or a financial electronics product. Consumer electronics products include mobile phones, tablets, laptops, e-readers, personal computers (PCs), personal digital assistants (PDAs), desktop monitors, smart wearable products (e.g., smartwatches, smart bracelets), virtual reality (VR) electronic devices, augmented reality (AR) electronic devices, drones, etc. Home electronics products include smart door locks, televisions, refrigerators, and rechargeable small household appliances (e.g., soymilk makers, robot vacuum cleaners), etc. In-vehicle electronics products include in-vehicle navigation systems, in-vehicle DVDs, etc. Financial electronics products include ATMs, self-service electronic devices, etc.

[0081] This application does not impose any special restrictions on the specific form of the above-mentioned electronic device. For the sake of convenience, the following embodiments all use mobile phones as an example for illustration.

[0082] Figure 1 is an architecture diagram of an electronic device provided in an embodiment of this application.

[0083] Taking a mobile phone as an example of the electronic device provided in this application embodiment, as exemplarily shown in FIG1, the electronic device 1 mainly includes a display module 2, a middle frame 3, a shell (or battery cover, back cover) 4 and a cover plate 5.

[0084] The display module 2 has a light-emitting side from which the display image can be seen and a back side opposite to the light-emitting side. The back side of the display module 2 is close to the middle frame 3, and the cover plate 5 is disposed on the light-emitting side of the display module 2.

[0085] The aforementioned display module 2 includes a display panel (DP). In one possible embodiment of this application, the display module 2 is a liquid crystal display module. In this case, the display panel is a liquid crystal display (LCD). Based on this, the display module 2 also includes a backlight unit (BLU) located on the back of the LCD (away from the side of the LCD used to display images). The backlight unit can provide a light source to the LCD so that each sub-pixel in the LCD can emit light to achieve image display.

[0086] In another possible embodiment of this application, the display module 2 is an organic light-emitting diode (OLED) display module. In this case, the display screen is an organic light-emitting diode (OLED) display screen. Since each subpixel in an OLED display screen has an electroluminescent layer, the OLED display screen can achieve self-illumination after receiving an operating voltage. In this case, the display module 2 with an OLED display screen does not need to include the aforementioned backlight module.

[0087] The cover plate 5 is located on the side of the display module 2 away from the middle frame 3. The cover plate 5 can be, for example, a cover glass (CG), which can have a certain degree of toughness.

[0088] The middle frame 3 is located between the display module 2 and the housing 4. The surface of the middle frame 3 away from the display module 2 is used to mount internal components such as batteries, printed circuit boards (PCBs), cameras, and antennas. After the housing 4 is closed with the middle frame 3, the aforementioned internal components are located between the housing 4 and the middle frame 3.

[0089] The aforementioned electronic device 1 also includes semiconductor devices such as a motherboard, system on chip (SOC), power management unit (PMU), and radio frequency integrated circuit (RFIC) disposed on the PCB. The PCB is used to carry the aforementioned semiconductor devices and to complete signal interaction with the aforementioned semiconductor devices.

[0090] With the development of electronic technology, the functions of electronic device 1 are becoming increasingly rich and comprehensive. The processing power of functional modules such as chips and power devices in electronic devices is constantly improving, and power consumption is also increasing, leading to excessively high local temperatures in the electronic device. If not addressed in time, this may affect the performance of electronic device 1, or even cause damage to electronic device 1, or trigger a safety accident.

[0091] Figure 2 is a schematic diagram of a temperature detection scheme provided in an embodiment of this application.

[0092] In some technologies, as shown in Figure 2, a negative temperature coefficient (NTC) circuit is set inside the SOC to detect the temperature of different areas of the silicon wafer, and the solder joint temperature of the corresponding area is calculated through steady-state thermal simulation. However, this method can only obtain the temperature of the internal area of ​​the silicon wafer where the NTC circuit is set, and the temperature of the solder joint area is calculated by software. It cannot obtain the temperature of devices and modules in the chip area.

[0093] In some technologies, as shown in Figure 2, the temperature of the area next to high-power devices (such as PMUs and RFICs) is obtained by soldering NTC resistors onto the PCB surface. The temperature of the device module cannot be directly conducted to the NTC resistor; it can only be indirectly conducted to the temperature of the test area through the air.

[0094] In some technologies, a temperature sensing chip is embedded within the location where the temperature to be measured. However, temperature sensing chips occupy a large area, which is not conducive to miniaturization and integration.

[0095] While the aforementioned temperature detection technologies all possess certain temperature detection capabilities, they cannot directly measure the temperature of the heat source under test, nor are they suitable for implementation in highly integrated structures. This application provides a temperature detection technology that can directly measure the real-time temperature of the heat source under test.

[0096] Figures 3A-5 are schematic diagrams of the structure of a flexible circuit board provided in the embodiments of this application.

[0097] This application provides a flexible printed circuit (FPC), as shown in FIG3A. The flexible printed circuit FPC includes a first flexible dielectric layer 10, a second flexible dielectric layer 20, a first trace 31, and a first thermistor NTC1.

[0098] The first flexible dielectric layer 10 and the second flexible dielectric layer 20 are stacked, and the first trace 31 and the first thermistor NTC1 are disposed between the first flexible dielectric layer 10 and the second flexible dielectric layer 20.

[0099] For example, the first flexible dielectric layer 10 serves as the surface layer of the flexible printed circuit board (FPC), and the material of the first flexible dielectric layer 10 includes a coverlay. The material of the second flexible dielectric layer 20 includes polyimide (PI).

[0100] The first trace 31 and the first thermistor NTC1 are spaced apart. In this embodiment, the method of spaced arrangement between the first trace 31 and the first thermistor NTC1 is not limited, as long as electrical isolation between the two can be achieved.

[0101] As shown in Figure 3A, the flexible printed circuit board (FPC) includes a first conductor layer 30, which is disposed between a first flexible dielectric layer 10 and a second flexible dielectric layer 20. A first trace 31 and a first thermistor NTC1 are disposed on the same layer. The first conductor layer 30 includes the first trace 31 and the first thermistor NTC1, and the first thermistor NTC1 and the first trace 31 are spaced apart (e.g., adjacent or non-adjacent) along a direction parallel to the first flexible dielectric layer 10. For example, the first trace 31 may be disposed on one side of the first thermistor NTC1, or the first trace 31 may be disposed on opposite sides of the first thermistor NTC1.

[0102] This reduces the spacer layer between the first trace 31 and the first thermistor NTC1, reduces temperature loss during the transfer of temperature from the first trace 31 to the first thermistor NTC1, and improves the detection accuracy of the first thermistor NTC1.

[0103] The spacing between the first trace 31 and the first thermistor NTC1 can be set by taking into account the process and performance requirements of the flexible printed circuit board (FPC). The smaller the spacing between the first trace 31 and the first thermistor NTC1, the more accurate the temperature detection result.

[0104] For example, the spacing between the first trace 31 and the first thermistor NTC1 is 5μm to 100μm. Optionally, the spacing between the first trace 31 and the first thermistor NTC1 is 5μm, 10μm, 20μm, 30μm, 40μm, 50μm, 60μm, 70μm, 80μm, 90μm, or 100μm.

[0105] This approach avoids situations where the first trace 31 and the first thermistor NTC1 are too far apart, resulting in lower detection accuracy and larger space requirements. Conversely, it prevents the first trace 31 and the first thermistor NTC1 from being too close, which could negatively impact the circuit performance of the flexible printed circuit board (FPC).

[0106] It should be noted that the spacing between the first trace and the first thermistor can be set in two ways, as shown in Figure 3A and Figure 3B.

[0107] The first conductor layer 30 may include multiple sets of alternately arranged first traces 31 and first thermistors NTC1. The structure in Figure 3A is a schematic diagram of one such arrangement. Alternatively, Figure 3A illustrates a flexible printed circuit board (FPC) comprising a single conductor layer, where the first traces and the first thermistors are spaced apart within the same layer. The flexible printed circuit board (FPC) may also include multiple conductor layers, with dielectric layers disposed between adjacent conductor layers.

[0108] Alternatively, as an example, Figure 3B illustrates another type of spacing arrangement. As shown in Figure 3B, the flexible printed circuit board (FPC) includes multiple conductor layers, with the first thermistor NTC1 and the first trace 31 disposed on different layers, i.e., the first thermistor NTC1 and the first trace 31 are located on different layers. The first trace 31 can be located above the first thermistor NTC1, or it can be located below the first trace 31; this embodiment of the application does not limit this.

[0109] A thermistor is a type of sensor resistor whose resistance changes with temperature. Based on their temperature coefficient, they are classified into positive temperature coefficient thermistors (PTC thermistors) and negative temperature coefficient thermistors (NTC thermistors). The resistance of a PTC thermistor increases with increasing temperature, while the resistance of a NTC thermistor decreases with increasing temperature. In the embodiments of this application, the first thermistor NTC1 can be either a PTC or a NTC thermistor.

[0110] As shown in Figure 3A, the flexible printed circuit board (FPC) also includes a first pin P1, a second pin P2, a third pin P3, and a fourth pin P4, all of which are exposed on the surface of the FPC. For example, either the first flexible dielectric layer 10 or the second flexible dielectric layer 20 can expose the first pin P1, the second pin P2, the third pin P3, and the fourth pin P4. Figure 3A is only one illustration.

[0111] The first thermistor NTC1 is coupled between the first pin P1 and the second pin P2, and the first trace 31 is coupled between the third pin P3 and the fourth pin P4.

[0112] For example, the first pin P1, the second pin P2, the third pin P3, and the fourth pin P4 are all located at the ends of the flexible circuit board (FPC). Along the extension direction of the first trace 31, the first pin P1 and the second pin P2 are located at opposite ends of the flexible circuit board (FPC), and the third pin P3 and the fourth pin P4 are respectively provided at the two ends of the first trace 31.

[0113] Alternatively, one or more of the first pin P1, the second pin P2, the third pin P3, and the fourth pin P4 may be located at a non-end position of the flexible circuit board (FPC), but this application embodiment does not limit this.

[0114] In some embodiments, the first conductor layer 30 includes a first thermistor NTC1.

[0115] For example, as shown in Figure 3A, the flexible circuit board (FPC) also includes a second trace 32. A first thermistor NTC1 is located on the second trace 32. The first thermistor is coupled between the first pin and the second pin through the second trace. For example, the two ends of the second trace 32 are coupled to the first pin P1 and the second pin P2, respectively.

[0116] The second routing line 32 can be parallel to the first routing line 31, or they can be non-parallel, as long as they do not intersect.

[0117] Alternatively, as shown in Figure 4, the two ends of the first thermistor NTC1 are directly coupled to the first pin P1 and the second pin P2.

[0118] This allows for the detection of the temperature of the entire first trace 31 that is spaced apart from (e.g., adjacent to) the first thermistor NTC1, providing a wide detection range.

[0119] In some other embodiments, as shown in FIG5, the first conductor layer 30 includes a plurality of first thermistors NTC1, which are connected in series between the first pin P1 and the second pin P2, and are arranged along the extension direction of the first trace 31.

[0120] The multiple first thermistors NTC1 are arranged at intervals, which can improve the accuracy of the test results and monitor the temperature change of the part of the first trace 31 adjacent to each first thermistor NTC1, making it easier to locate the specific heat-generating location of the first trace 31.

[0121] For example, the spacing between adjacent first thermistors NTC1 is d, 0.05mm≤d≤2mm. For example, the value of d is 0.5mm, 0.1mm, 0.3mm, 0.5mm, 0.7mm, 0.9mm, 1mm, 1.1mm, 1.3mm, 1.5mm, 1.7mm, 1.9mm or 2mm.

[0122] By setting the spacing between adjacent first thermistors NTC1 within the range of 0.05mm-2mm, the processing error of the first thermistors NTC1 can be reduced and the accuracy improved.

[0123] In this embodiment, the first thermistor NTC1 and the first pin P1 and the second pin P2 may be located on the same side or on different layers. This embodiment does not limit this.

[0124] The flexible printed circuit board (FPC) provided in this application integrates a first thermistor NTC1 inside the FPC. The first thermistor NTC1 is spaced apart from the first trace 31. By observing the change in the resistance of the first thermistor NTC1 with temperature, the temperature change at the location of the first thermistor NTC1 is detected, thereby achieving the purpose of detecting the temperature change of the first trace 31 inside the flexible printed circuit board (FPC), without the need for additional temperature detection devices. The first thermistor NTC1 can be flexibly arranged to detect the temperature of various first traces 31 in real time.

[0125] In some embodiments, the temperature change rate of the first thermistor NTC1 is greater than or equal to 2Ω / ℃. For example, the temperature change rate of the first thermistor NTC1 is 2Ω / ℃, 3Ω / ℃, 5Ω / ℃, 7Ω / ℃, 10Ω / ℃, 13Ω / ℃, 15Ω / ℃, 17Ω / ℃, or 20Ω / ℃, etc.

[0126] For example, the resistance of the first thermistor NTC1 varies by one order of magnitude between 0°C and 150°C.

[0127] By limiting the temperature change rate of the first thermistor NTC1 to greater than or equal to 2Ω / ℃, the feedback voltage output by the first thermistor NTC1 is easy to acquire, which can reduce the accuracy requirements of the acquisition equipment and reduce costs. Of course, the temperature change rate of the thermistor can also be less than 2Ω / ℃.

[0128] In some embodiments, the center resistance of the first thermistor NTC1 is 200Ω to 3000Ω. For example, the center resistance of the first thermistor NTC1 is 200Ω, 300Ω, 500Ω, 700Ω, 1000Ω, 1300Ω, 1500Ω, 1700Ω, 2000Ω, 2300Ω, 2500Ω, 2700Ω, or 3000Ω, etc.

[0129] The voltage output from pins P1 and P2 reflects the resistance change of the first thermistor NTC1, and the output voltage is directly proportional to the center resistance value. Therefore, if the center resistance value of the first thermistor NTC1 is too small, its temperature change will be small, the current change across it will be insignificant, and the output voltage will be too low to be easily detected, affecting the accuracy of temperature detection. Conversely, if the center resistance value of the first thermistor NTC1 is too large, the resistor area needs to be increased, resulting in excessive trace resources and hindering its integration into the PCB. The ideal center resistance value for the first thermistor NTC1 can be obtained through circuit design.

[0130] In some embodiments, the sheet resistance of the first thermistor NTC1 is 50Ω to 3000Ω. For example, the sheet resistance of the first thermistor NTC1 is 50Ω, 5100Ω, 200Ω, 300Ω, 500Ω, 700Ω, 1000Ω, 1300Ω, 1500Ω, 1700Ω, 2000Ω, 2300Ω, 2500Ω, 2700Ω, or 3000Ω, etc.

[0131] Sheet resistance is the resistance between edges of a square thin-film conductive material. The product of sheet resistance and L / W (L: length, W: width) is the center resistance value.

[0132] If the sheet resistance of the first thermistor NTC1 is too small, more wiring resources are needed to obtain the target thin-film resistance center value. If the center value of the first thermistor NTC1 is too small, the resistance change of the first thermistor NTC1 with temperature changes will be relatively small, and the current change on the first thermistor NTC1 will not be obvious, making it difficult to detect and affecting the accuracy of temperature detection. If the sheet resistance of the first thermistor NTC1 is too large, it is difficult to achieve a high temperature coefficient of resistance (TCR). Similarly, the ratio of the resistance change caused by temperature change to the total resistance is reduced, and the detectable voltage change is smaller, which is not conducive to obtaining accurate temperature change values.

[0133] In some embodiments, the first thermistor NTC1 is a thin-film resistor. This reduces the area occupied by the first thermistor NTC1, which is beneficial for the integration of the thermistor into the flexible printed circuit board (FPC).

[0134] The flexible printed circuit board (FPC) provided in this application integrates a first thermistor NTC1. The first thermistor NTC1 is disposed adjacent to the first trace 31. Temperature changes at the location of the first thermistor NTC1 are detected by observing the change in its resistance with temperature, eliminating the need for additional processing components. The first thermistor NTC1 is a thin-film resistor, facilitating its integration into the FPC. Furthermore, the first thermistor NTC1 can be flexibly arranged within the FPC according to temperature measurement requirements, enabling real-time temperature detection at various measurement locations.

[0135] Figure 6A is a topological schematic diagram of a detection circuit provided in an embodiment of this application. Figure 6B is a cross-sectional view of a flexible circuit board provided in an embodiment of this application.

[0136] In some embodiments, as shown in FIG6A, the flexible circuit board FPC further includes a first resistor R1 and a fifth pin P5, wherein the first resistor R1 is coupled between the fifth pin P5 and the first pin P1.

[0137] For example, as shown in Figure 6B, the first resistor R1 is disposed on the side of the second flexible dielectric layer 20 away from the first thermistor NTC1. The flexible printed circuit board (FPC) also includes a second conductor layer 40 and a third flexible dielectric layer 50. The second conductor layer 40 is disposed on the side of the second flexible dielectric layer 20 away from the first conductor layer 30, and the third flexible dielectric layer 50 is disposed on the side of the second conductor layer 40 away from the first conductor layer 30. The second conductor layer 40 includes the first resistor R1. For example, the first resistor R1 passes through the second flexible dielectric layer 20 and is coupled to the first pin P1 to realize the series connection between the first resistor R1 and the first thermistor NTC1.

[0138] The second conductor layer 40 and the first conductor layer 30 can be two adjacent conductor layers on a flexible circuit board (FPC), or they can be two non-adjacent conductor layers on a flexible circuit board (FPC). Figure 6B is only one illustration.

[0139] Alternatively, for example, the first resistor R1 and the first thermistor NTC1 are disposed on the same layer.

[0140] In some embodiments, the first resistor R1 is a thin-film resistor. This reduces the area occupied by the first resistor R1 and enables its integration on the flexible printed circuit board (FPC).

[0141] Alternatively, for example, the first resistor R1 and the first thermistor NTC1 are disposed on the same layer.

[0142] The fifth pin P5 is exposed on the surface of the flexible circuit board (FPC). For example, the fifth pin P5 can be set on the same layer as the first pin P1, the second pin P2, the third pin P3, and the fourth pin P4.

[0143] By setting a first resistor R1 connected in series with the first thermistor NTC1, it is equivalent to setting a pull-up resistor, which can increase the series resistance of the first resistor R1 and the first thermistor NTC1, thereby reducing the power consumption of the detection circuit.

[0144] Figure 6C is a topology diagram of a detection circuit provided in an embodiment of this application.

[0145] In some embodiments, as shown in FIG6C, the flexible circuit board FPC further includes a capacitor C, which is connected in parallel with a first thermistor NTC1 between the first pin P1 and the second pin P2.

[0146] The embodiments of this application do not limit the integration method of capacitor C in flexible circuit board (FPC). For example, the first electrode of capacitor C can be formed in the first conductor layer 30 and the second electrode of capacitor C can be formed in the second conductor layer 40.

[0147] A filter can be constructed by setting a capacitor C in parallel with the first thermistor NTC1 to improve the accuracy of temperature detection.

[0148] Figure 7A is a topological schematic diagram of a detection circuit provided in an embodiment of this application. Figure 7B is a cross-sectional view of a flexible circuit board provided in an embodiment of this application.

[0149] In some embodiments, as shown in FIG7A, the flexible circuit board FPC further includes a sixth pin P6 and a Wheatstone bridge, with the sixth pin P6 exposed on the surface of the flexible circuit board FPC.

[0150] The Wheatstone bridge includes a first input terminal I1, a second input terminal I2, a first output terminal O1, a second output terminal O2, a first thermistor NTC1, and multiple second resistors R2. The first input terminal I1 and the second input terminal I2 are coupled to the sixth pin P6, the first output terminal O1 is coupled to the first pin P1, the second output terminal O2 is coupled to the second pin P2, and the second resistors R2 are thin-film resistors.

[0151] The embodiments of this application do not limit the structure of the Wheatstone bridge, and the structures of Wheatstone bridges in related technologies are applicable to the embodiments of this application. For example, as shown in FIG7A, the Wheatstone bridge includes four resistors, three of which are non-thermostats and one is a thermistor. The plurality of second resistors R2 include second resistor R2-1, second resistor R2-2, and second resistor R2-3.

[0152] One end of the first thermistor NTC1 is coupled to the first input terminal I1, and the other end of the first thermistor NTC1 is coupled to the first output terminal O1. One end of the second resistor R2-1 is coupled to the first input terminal I1, and the other end of the second resistor R2-1 is coupled to the second output terminal O2. One end of the second resistor R2-2 is coupled to the first output terminal O1, and the other end of the second resistor R2-2 is coupled to the second input terminal I2. One end of the second resistor R2-3 is coupled to the second output terminal O2, and the other end of the second resistor R2-3 is coupled to the second input terminal I2.

[0153] In a Wheatstone bridge, any one of the following resistors can be a thermistor: the first thermistor NTC1, the second resistors R2-1, R2-2, and R2-3. That is, the resistor coupled between the first input terminal I1 and the first output terminal O1 can be a thermistor, and the second resistors R2-1, R2-2, and R2-3 can be non-thermal resistors. Alternatively, the second resistor R2-1 can be a thermistor, and the resistors coupled between the first input terminal I1 and the first output terminal O1, as well as the second resistors R2-2 and R2-3, can be non-thermal resistors. Or, the second resistor R2-2 can be a thermistor, and the resistors coupled between the first input terminal I1 and the first output terminal O1, as well as the second resistors R2-1 and R2-3, can be non-thermal resistors. Alternatively, the second resistor R2-3 can be a thermistor, and the resistors coupled between the first input terminal I1 and the first output terminal O1, the second resistor R2-1, and the second resistor R2-2 can be non-thermostats.

[0154] Alternatively, for example, multiple, but not all, of the first thermistor NTC1, the second resistors R2-1, R2-2, and R2-3 may be thermistors. That is, the resistor coupled between the first input terminal I1 and the first output terminal O1 and the second resistor R2-1 may be thermistors, while the second resistors R2-2 and R2-3 may be non-thermistors. Alternatively, the second resistors R2-2 and R2-3 may be thermistors, while the resistor coupled between the first input terminal I1 and the first output terminal O1 and the second resistor R2-1 may be non-thermistors, and so on.

[0155] In some embodiments, the center resistance of the first thermistor NTC1 is equal to the center resistance of the second resistor R2-1, the center resistance of the second resistor R2-2 is equal to the center resistance of the second resistor R2-3, and the center resistance of the first thermistor NTC1 is not equal to the center resistance of the second resistor R2-2.

[0156] In the Wheatstone bridge shown in Figure 7A, the null or balanced conditions are used to locate the unknown resistor. The resistor coupled between the first input terminal I1 and the first output terminal O1 is a thermistor. Since R in the Wheatstone bridge... NTC1 *R 2-3 =R 2-2 *R 2-1 Therefore, when there is no temperature change, R NTC1 *R 2-3 -R 2-2 *R 2-1 =0, U P1-P2 / U P3 =(R NTC1 *R 2-3 -R2-2 *R 2-1 ) / [(R NTC1 +R 2-2 )*(R 2-3 +R 2-1 Wheatstone bridge output U P1-P2 =0. When the temperature changes, the resistance of the thermistor changes, R NTC1 ′*R 2-3 -R 2-2 *R 2-1 ≠0U P1-P2 / U P3 =(R NTC1 ′*R 2-3 -R 2-2 *R 2-1 ) / [(R NTC1 ′+R 2-2 )*(R 2-3 +R 2-1 Wheatstone bridge output U P1-P2 ≠0. With the resistance values ​​of the second resistors R2-1, R2-2, and R2-3 fixed, through U... P1-P2 The resistance value (R) of the first thermistor NTC1 can be obtained. NTC1 The temperature change can be obtained further by analyzing the temperature change rate of the thermistor.

[0157] Among them, R NTC1 R is the resistance of the first thermistor NTC1 when there is no temperature change. NTC1 R' represents the resistance of the first thermistor NTC1 when the temperature changes. 2-1 Let R be the resistance value of the second resistor R2-1. 2-2 Let R be the resistance value of the second resistor R2-2. 2-3 U is the resistance value of the second resistor R2-3. P3 U is the voltage at pin 5 P5. P1-P2 This is the output voltage of the Wheatstone bridge.

[0158] In other embodiments, the center resistance values ​​of the first thermistor NTC1, the second resistor R2-1, the second resistor R2-2, and the second resistor R2-3 are equal. This simplifies the design and fabrication process.

[0159] In some embodiments, the sheet resistance of the second resistor R2 in the Wheatstone bridge is 200Ω to 3000Ω. For example, the sheet resistance of the second resistor R2 is 200Ω, 300Ω, 500Ω, 700Ω, 1000Ω, 1300Ω, 1500Ω, 1700Ω, 2000Ω, 2300Ω, 2500Ω, 2700Ω, or 3000Ω, etc.

[0160] In some embodiments, the center resistance of the second resistor R2 is 200Ω to 3000Ω. For example, the center resistance of the second resistor R2 is 200Ω, 300Ω, 500Ω, 700Ω, 1000Ω, 1300Ω, 1500Ω, 1700Ω, 2000Ω, 2300Ω, 2500Ω, 2700Ω, or 3000Ω, etc.

[0161] In some embodiments, the second resistor R2 is located in the first conductor layer 30.

[0162] In some other embodiments, as shown in FIG7B, the flexible circuit board FPC further includes a third conductor layer 60 and a fourth flexible dielectric layer 70, the third conductor layer 60 and the fourth flexible dielectric layer 70 being disposed sequentially on the side of the first conductor layer 30 away from the first flexible dielectric layer 10, and the second resistor R2 being located on the third conductor layer 60.

[0163] By employing a Wheatstone bridge to detect temperature changes, the resulting change in resistance of the first thermistor NTC1 can be amplified. This improves the accuracy of temperature detection while maintaining the same length of the first thermistor NTC1. Furthermore, the length of the first thermistor NTC1 can be reduced while maintaining the same detection accuracy.

[0164] Figure 7C is a topological schematic diagram of a detection circuit provided in an embodiment of this application. Figure 7D is a cross-sectional view of a flexible circuit board provided in an embodiment of this application.

[0165] In some embodiments, as shown in FIG7C, the flexible circuit board FPC further includes a third resistor R3 and a seventh pin P7, the seventh pin P7 being exposed on the surface of the flexible circuit board FPC, and the third resistor R3 being coupled between the seventh pin P7 and the first input terminal I1.

[0166] The third resistor R3 can be installed in the same layer or in a different layer than the second resistor R2. Figure 7D illustrates an example where the third resistor R3 and the second resistor R2 are installed in the same layer.

[0167] The third resistor R3 is connected in series with the Wheatstone bridge and acts as a pull-up resistor, which can reduce the overall power consumption of the flexible printed circuit board (FPC). Figures 8A and 8B are schematic diagrams of a circuit board assembly provided in an embodiment of this application.

[0168] This application also provides a circuit board assembly (PCBA), as shown in FIG8A. The PCBA includes a rigid circuit board (PCB), any of the aforementioned flexible circuit boards (FPC), and a processing unit. A first pin P1 is connected to the rigid circuit board (PCB), and the processing unit is coupled to the first pin P1. The processing unit may, for example, be disposed on the rigid circuit board (PCB).

[0169] The voltage measured by the first thermistor NTC1 in the flexible printed circuit board (FPC) for temperature feedback is transmitted to the processing unit, which processes the voltage to obtain the temperature at the location of the first thermistor NTC1. The temperature at the location of the first thermistor NTC1 can be used to feed back the temperature of the adjacent first trace 31. For example, Rt = R T0 +α(T-T0), where Rt is the resistance of the first thermistor NTC1 after temperature change, R T0 The resistance of the first thermistor NTC1 at room temperature is given by α, where α is the temperature change coefficient, T0 is the room temperature, and T is the current temperature. The processing unit obtains the resistance of the first thermistor NTC1 after the temperature change, and thus determines the current temperature at the location of the first thermistor NTC1.

[0170] The processing unit may include, for example, a microcontroller unit (MCU), which uses the redundant channels of the existing MCU on the circuit board to detect the voltage change of the first thermistor NTC1, thereby obtaining the resistance change and ultimately the temperature change.

[0171] As shown in Figure 8A, the first resistor R1 may not be provided in the flexible circuit board FPC included in the circuit board assembly PCBA.

[0172] As shown in Figure 8B, a first resistor R1 can also be provided in the flexible circuit board FPC included in the circuit board assembly PCBA.

[0173] Figures 8C and 8D are schematic diagrams of another circuit board assembly provided in the embodiments of this application.

[0174] In some embodiments, as shown in FIG8C, the circuit board assembly PCBA further includes a first resistor R1, which is, for example, a device resistor and can be disposed on a rigid circuit board PCB. The first resistor R1 is coupled to the rigid circuit board PCB to couple the first resistor R1 to the first pin P1, thereby realizing the series connection of the first resistor R1 and the first thermistor NTC1.

[0175] By setting a first resistor R1 in series with the first thermistor NTC1, it is equivalent to setting a pull-up resistor, which increases the series resistance of the first resistor R1 and the first thermistor NTC1, thereby reducing the power consumption of the detection circuit. When it is inconvenient to integrate thin-film resistors in a flexible printed circuit board (FPC), the first resistor R1 can be set by using an external resistor.

[0176] In some embodiments, as shown in FIG8D, the circuit board assembly PCBA further includes a capacitor C disposed on a rigid circuit board PCB and coupled to the rigid circuit board PCB to realize parallel coupling between the capacitor C and the first thermistor NTC1.

[0177] Figures 9A-9C are schematic diagrams of the topology of a detection circuit provided in an embodiment of this application.

[0178] As shown in Figures 9A-9C, the resistance of the first thermistor NTC1 changes with temperature. The change in the resistance of the first thermistor NTC1 is transmitted to the MCU in the form of a voltage change. The MCU obtains the change in the resistance of the first thermistor NTC1 based on the voltage change, and thus infers the temperature change.

[0179] Figure 10A is a schematic diagram of the structure of another circuit board assembly provided in an embodiment of this application, and Figure 10B is a schematic diagram of the topology of a detection circuit provided in an embodiment of this application.

[0180] In some embodiments, as shown in FIG10A, the circuit board assembly PCBA further includes a third resistor R3, which is coupled to the first input terminal I1.

[0181] By adding a third resistor R3 in series with the Wheatstone bridge, a pull-up resistor is essentially added, increasing the series resistance between R3 and the Wheatstone bridge to reduce power consumption in the detection circuit. When it's inconvenient to integrate thin-film resistors in a flexible printed circuit (FPC), the third resistor R3 can be set using an external resistor.

[0182] As shown in Figure 10B, the resistance of the first thermistor NTC1 changes with temperature. The change in the resistance of the first thermistor NTC1 is transmitted to the MCU in the form of a voltage change. The MCU obtains the change in the resistance of the first thermistor NTC1 based on the voltage change, and thus infers the temperature change.

[0183] Figure 11 is a schematic diagram of the structure of an electronic device provided in an embodiment of this application.

[0184] The circuit board assembly provided in this application embodiment can be applied to the electronic device provided in this application embodiment. For example, as shown in FIG11, the electronic device is a folding electronic device, and the flexible circuit board FPC is a flexible circuit board passing through the pivot. The two ends of the flexible circuit board FPC are respectively coupled to a PCB.

[0185] During the use of electronic device 1, metal shavings may fall into the trace layer of the flexible printed circuit board (FPC). When the metal shavings come into contact with the first trace 31, the first trace 31 will short-circuit, causing the temperature of the first trace 31 at the location of the metal shavings to rise. At this time, the temperature change is transmitted to the MCU in the form of a change in the resistance value of the first thermistor NTC1.

[0186] Figure 12 is a schematic diagram of the display interface of an electronic device provided in an embodiment of this application.

[0187] When the temperature change exceeds the set temperature, the MCU feeds back the temperature rise of the first trace 31 to the processor of the electronic device, as shown in Figure 12. The processor controls the electronic device to pop up an interface reminder to repair the flexible circuit board (FPC). Of course, this embodiment does not limit the specific method of the reminder interface; Figure 12 is only one illustration. Alternatively, the processor controls the electronic device 1 to automatically shut down and restart. Alternatively, the processor controls the electronic device 1 to activate a backup path.

[0188] Figure 13 is a flowchart of the fabrication process of a flexible circuit board provided in an embodiment of this application, and Figures 14A-14D are schematic diagrams of the fabrication process of a flexible circuit board provided in an embodiment of this application.

[0189] This application embodiment also provides a method for fabricating a flexible circuit board, as shown in Figure 13. The method for fabricating a flexible circuit board includes:

[0190] S10, Forming the second flexible dielectric layer 20.

[0191] The embodiments of this application do not limit the method of forming the second flexible dielectric layer 20. For example, the second flexible dielectric layer 20 can be formed by a vapor deposition process.

[0192] S20. A first trace 31, a first thermistor NTC1, a first pin P1, a second pin P2, a third pin P3, and a fourth pin P4 are formed on one side of the second flexible dielectric layer 20. The first trace 31 and the first thermistor NTC1 are spaced apart. The first thermistor NTC1 is coupled between the first pin P1 and the second pin P2. The first thermistor NTC1 is a thin-film resistor. The first trace 31 is coupled between the third pin P3 and the fourth pin P4.

[0193] The first trace 31 and the first thermistor NTC1 can be spaced apart along a direction parallel to the thickness of the flexible circuit board (FPC), or they can be spaced apart along a direction perpendicular to the thickness of the FPC (parallel to the second dielectric layer 20). Regardless of the method, the fabrication process of the first thermistor NTC1 is the same. Below, we will illustrate the fabrication method of the first thermistor NTC1 using the example of the first trace 31 and the first thermistor NTC1 being spaced apart along a direction perpendicular to the thickness of the FPC (parallel to the second dielectric layer 20).

[0194] For example, step S20 includes:

[0195] S21. As shown in Figure 14A, a thermistor film NTC' and a wire film 31' are sequentially formed on one side of the second flexible dielectric layer 20.

[0196] For example, a thermistor film NTC' can be formed using a sputtering process. The material of the thermistor film NTC' may include, for example, a mixed metal, into which a temperature-sensitive semiconductor compound is incorporated to form a temperature-sensitive thin-film resistor layer on the surface of the second flexible dielectric layer 20. The material of the thermistor film NTC' may include, for example, a nickel-chromium mixed metal. Then, a conductive film 31' is formed using a vapor deposition process, a lamination process, or an electroplating process. The material of the conductive film 31' may include, for example, copper (Cu).

[0197] The thickness of the thermistor film NTC' is, for example, 5nm to 100nm, to improve the robustness of the thermistor film NTC'. For example, the thickness of the thermistor film NTC' is, for example, 5nm, 10nm, 20nm, 30nm, 40nm, 50nm, 60nm, 70nm, 80nm, 90nm, or 100nm.

[0198] S22. As shown in Figure 14B, the conductive film 31' and the thermistor film NTC' are patterned to form a first stacked pattern 311 and a second stacked pattern 312. The first conductive film and the thermistor film stacked pattern 311 serves as the first trace 31.

[0199] For example, a wet etching process is used to pattern the conductive film 31' and the thermistor film NTC'.

[0200] For example, a photoresist is formed on the surface of the conductive film 31', covering the conductive film 31'. The thermistor film NTC' and the conductive film 31' are patterned using an exposure, development, and acid etching process. The photoresist is retained where the circuitry needs to be preserved, and removed where it is not needed, revealing the thermistor film NTC' and the conductive film 31' to be etched. An acid etching solution is used to remove the portions of the thermistor film NTC' and the conductive film 31' not covered by the photoresistor, leaving the portions covered by the photoresistor. An organic or alkaline stripping solution is used to remove the photoresistor, exposing the remaining thermistor film NTC' and the conductive film 31'. The remaining thermistor film NTC' and the conductive film 31' serve as the first layer pattern 311 and the second layer pattern 312. The first conductive film and thermistor film stacked pattern 311 serves as the first trace 31, while the second stacked pattern 312 requires further processing.

[0201] S23. As shown in Figure 14C, the conductive film 31' in the second stacked pattern 312 is patterned to expose part of the thermistor film NTC' as the first thermistor NTC1.

[0202] For example, a wet etching process is used to pattern the conductive film 31' in the second stacked pattern 312.

[0203] For example, a dry film is formed on the surface of the second stacked pattern 312, covering the second stacked pattern 312 and the first conductive film and thermistor film stacked pattern 311. The conductive film 31' in the second stacked pattern 312 is patterned using an exposure, development, and alkaline etching process. The dry film at the location where the thermistor film NTC' is to be formed is removed, while the dry film at other locations is retained, revealing the conductive film 31' to be etched. An alkaline etching solution is used to remove the portion of the conductive film 31' not covered by the dry film, leaving the portion covered by the dry film. The retained portion of the conductive film 31' serves as the wiring for interconnecting the first thermistor NTC1 with the first pin P1 and the second pin P2. The thermistor film NTC' will not be etched by the alkaline etching solution. The portion of the thermistor film NTC' covered by the conductor film 31' is used as a conductor, and the portion of the thermistor film NTC' exposed by the conductor film 31' serves as the first thermistor NTC1. The alkaline etching solution can be, for example, a composition of copper chloride (CuCl2) + hydrochloride (HCl) + hydrogen peroxide (H2O2) + water (H2O).

[0204] The resistance value of the first thermistor NTC1 is determined by the length and width of the exposed thermistor film NTC'. For example, if the width of the first thermistor NTC1 is 50μm, and the design of a first thermistor NTC1 with a center resistance value of 1500 to 2500Ω and a sheet resistance of 50Ω to 3000Ω (e.g., 500Ω) requires differential etching to expose a single resistance segment with a length of 100μm to 200μm.

[0205] For example, while fabricating the first thermistor NTC1 and the first trace 31, the first pin P1, the second pin P2, the third pin P3 and the fourth pin P4 are also fabricated.

[0206] S30, a first flexible dielectric layer 10 is formed on the side of the first trace 31 and the first thermistor NTC1 away from the second flexible dielectric layer 20.

[0207] The first pin P1 and the second pin P2 are exposed on the surface of the flexible circuit board (FPC). The illustrations in this application are merely schematic and do not constitute a limitation on the structure of the embodiments of this application.

[0208] When the flexible printed circuit board (FPC) also includes a non-thermostat, the preparation process of the non-thermostat can be the same as that of the thermistor, except that the thermistor film is replaced with an ordinary resistor film.

[0209] Figure 15 is a schematic diagram of the structure of a temperature detection device provided in an embodiment of this application.

[0210] This application embodiment also provides a temperature detection device, as shown in FIG15. The temperature detection device 100 includes a first dielectric layer 110, a first conductor layer 130 and a second dielectric layer 120 stacked together.

[0211] A first conductor layer 130 is disposed between a first dielectric layer 110 and a second dielectric layer 120, and the first conductor layer 130 includes a first thermistor NTC1. The temperature sensing device 100 also includes a first pin P1 and a second pin P2, which are exposed on the surface of the temperature sensing device 100.

[0212] The first thermistor NTC1 is coupled between the first pin P1 and the second pin P2. The first thermistor NTC1 is a thin film resistor.

[0213] This application does not limit the specific location of the first pin P1 and the second pin P2 in the temperature sensing device 100; Figure 15 is merely an illustration. For example, the first pin P1 and the second pin P2 are located on the first conductor layer 130, and the first pin P1 and the second pin P2 are coupled to the first thermistor NTC1 via wires located on the first conductor layer 130. In this application embodiment, the first thermistor NTC1 and the first pin P1 and the second pin P2 may be located on the same side or not on the same layer; this application embodiment does not limit this.

[0214] The first pin P1 and the second pin P2 are exposed on the surface of the temperature sensing device 100. This can be achieved by the first dielectric layer 110 exposing the first pin P1 or the second pin P2, or by the second dielectric layer 120 exposing the first pin P1 or the second pin P2. This application embodiment does not limit this, and the figure is only an illustration.

[0215] The temperature detection device 100 provided in this application embodiment is an independent device. The heat source to be tested is not directly connected to the temperature detection device 100. The first thermistor NTC1 in the temperature detection device 100 is close to the heat source to be tested (device, pad, trace, component, etc.) to detect the temperature of the heat source to be tested. The layout is flexible and does not affect the power consumption of the heat source to be tested.

[0216] In some embodiments, as shown in FIG15, the temperature sensing device 100 includes a first thermistor NTC1.

[0217] Figure 16 is a schematic diagram of another temperature detection device provided in an embodiment of this application.

[0218] Alternatively, as shown in Figure 16, the first conductor layer 130 includes a plurality of first thermistors NTC1, which are connected in series between the first pin P1 and the second pin P2.

[0219] For example, the spacing between adjacent first thermistors NTC1 is d, where 0.05mm ≤ d ≤ 2mm. For example, the value of d can be 0.05mm, 0.1mm, 0.3mm, 0.5mm, 0.7mm, 0.9mm, 1mm, 1.1mm, 1.3mm, 1.5mm, 1.7mm, 1.9mm, or 2mm.

[0220] The embodiments of this application do not limit the trajectory shape of the first conductor layer 130; Figures 15 and 16 are merely schematic representations.

[0221] In some embodiments, the first dielectric layer 110 and the second dielectric layer 120 may be rigid dielectric layers or flexible dielectric layers; the embodiments of this application do not limit this.

[0222] Figures 17A and 17B are schematic diagrams of another temperature detection device provided in the embodiments of this application.

[0223] In some embodiments, the temperature sensing device 100 includes the detection circuit shown in FIG. 6A. For example, as shown in FIG. 17A, the temperature sensing device 100 further includes a second conductor layer 140 disposed on the side of the second dielectric layer 120 away from the first conductor layer 130. The second conductor layer 140 includes a first resistor R1, which is a thin-film resistor.

[0224] The temperature sensing device 100 also includes a fifth pin P5, and a first resistor R1 is coupled between the fifth pin P5 and the first pin P1.

[0225] The first thermistor NTC1 and the first pin P1 can be located on the same layer, or the first resistor R1 and the first pin P1 can be located on the same layer. This application does not limit this.

[0226] For example, the fifth pin P5 is located on the same layer as the first pin P1 and the second pin P2, and the first dielectric layer 110 exposes the fifth pin P5.

[0227] For example, the temperature sensing device 100 also includes a third dielectric layer 150 disposed on the side of the second conductor layer 140 away from the first conductor layer 130.

[0228] In some embodiments, the temperature sensing device 100 includes the detection circuit shown in FIG. 6B. For example, as shown in FIG. 17B, the temperature sensing device 100 further includes a capacitor C, which is coupled in parallel with a first thermistor NTC1 between a first pin P1 and a second pin P2.

[0229] The integration method of capacitor C in temperature sensing device 100 is not limited in this application embodiment. For example, a part of the structure in the first conductor layer 130 can be used as the first electrode of capacitor C, and a part of the structure in the second conductor layer 140 can be used as the second electrode of capacitor C.

[0230] Figure 18 is a schematic diagram of another temperature detection device provided in an embodiment of this application.

[0231] In some embodiments, as shown in FIG18, the temperature sensing device 100 further includes a third conductor layer 160 and a Wheatstone bridge, wherein the third conductor layer is disposed on the side of the second dielectric layer 120 away from the first conductor layer 130.

[0232] The temperature sensing device 100 also includes a sixth pin P6, which is exposed on the surface of the temperature sensing device 100.

[0233] The Wheatstone bridge includes a first input terminal I1, a second input terminal I2, a first output terminal O1, a second output terminal O2, a first thermistor NTC1, and multiple second resistors R2. The first input terminal I1 and the second input terminal I2 are coupled to a sixth pin P6, the first output terminal O1 is coupled to a first pin P1, the second output terminal O2 is coupled to a second pin P2, and the second resistors R2 are located on either the first conductor layer 130 or the third conductor layer 160. The second resistors R2 are thin-film resistors.

[0234] The embodiments of this application do not limit the structure of the Wheatstone bridge, and the structures of Wheatstone bridges in related technologies are applicable to the embodiments of this application. For example, as shown in Figure 18, the Wheatstone bridge includes four resistors, three of which are non-thermostats and one is a thermistor. The plurality of second resistors R2 include second resistor R2-1, second resistor R2-2, and second resistor R2-3.

[0235] One end of the first thermistor NTC1 is coupled to the first input terminal I1, and the other end of the first thermistor NTC1 is coupled to the first output terminal O1. One end of the second resistor R2-1 is coupled to the first input terminal I1, and the other end of the second resistor R2-1 is coupled to the second output terminal O2. One end of the second resistor R2-2 is coupled to the first output terminal O1, and the other end of the second resistor R2-2 is coupled to the second input terminal I2. One end of the second resistor R2-3 is coupled to the second output terminal O2, and the other end of the second resistor R2-3 is coupled to the second input terminal I2.

[0236] For example, as shown in Figure 18, the temperature sensing device 100 also includes a fourth dielectric layer 170, which is disposed on the side of the third conductor layer 160 away from the first conductor layer 130.

[0237] By employing a Wheatstone bridge to detect temperature changes, the resulting change in resistance of the first thermistor NTC1 can be amplified. This improves the accuracy of temperature detection while maintaining the same length of the first thermistor NTC1. Furthermore, the length of the first thermistor NTC1 can be reduced while maintaining the same detection accuracy.

[0238] Figure 19 is a schematic diagram of another temperature detection device provided in an embodiment of this application.

[0239] In some embodiments, as shown in FIG19, the temperature sensing device 100 further includes a third resistor R3 and a seventh pin P7, the seventh pin P7 being exposed on the surface of the temperature sensing device 100. The third resistor R3 is disposed on the same layer or on a different layer than the second resistor R2. FIG19 illustrates an example where the third resistor R3 and the second resistor R2 are disposed on the same layer. The third resistor R3 is coupled between the seventh pin P7 and the first input terminal I1.

[0240] The third resistor R3 is connected in series with the Wheatstone bridge and acts as a pull-up resistor, which can reduce the overall power consumption of the temperature sensing device 100.

[0241] Figures 20A and 20B are schematic diagrams of another temperature detection device provided in the embodiments of this application.

[0242] In some embodiments, as shown in FIG20A, the first conductor layer 130 further includes a second thermistor NTC2, an eighth pin P8, and a ninth pin P9. The second thermistor NTC2 is spaced apart from the first thermistor NTC1. The eighth pin P8 and the ninth pin P9 are exposed on the surface of the temperature sensing device 100. The second thermistor NTC2 is coupled between the eighth pin P8 and the ninth pin P9. The second thermistor NTC2 is a thin film resistor.

[0243] In other words, the temperature sensing device 100 can integrate multiple sensing circuits, which can be any of the sensing circuits illustrated above. The multiple sensing circuits can have the same structure or different structures.

[0244] As shown in Figure 20B, the sheet resistance of the first thermistor NTC1 and the second thermistor NTC2 can be adjusted by adjusting the winding method. Furthermore, this embodiment does not limit the layout of the first thermistor NTC1 and the second thermistor NTC2; they only need to be electrically isolated from each other. The windings of the first thermistor NTC1 and the second thermistor NTC2 can be straight or curved. This embodiment is merely illustrative and does not impose any limitations.

[0245] By setting multiple adjacent detection circuits in the temperature detection device 100, and having multiple detection circuits work independently, the accuracy of the temperature detection device 100 can be improved.

[0246] Figure 21 is a schematic diagram of another temperature detection device provided in an embodiment of this application.

[0247] In some embodiments, as shown in FIG21, the first dielectric layer 110 includes a first opening 111, and the first opening 111 is offset from (does not overlap with) the first thermistor NTC1.

[0248] The first dielectric layer 110 may include one or more first openings 111, wherein the first opening 111 does not expose the first thermistor NTC1.

[0249] In some other embodiments, as shown in FIG21, the second dielectric layer 120 includes a second opening 121, which is offset from (does not overlap with) the first thermistor NTC1.

[0250] The second dielectric layer 120 may include one or more second openings 121, wherein the second openings 121 do not expose the first thermistor NTC1.

[0251] In the temperature sensing device 100, the first opening 111 may be provided only in the first dielectric layer 110, the second opening 121 may be provided only in the second dielectric layer 120, or the first opening 111 may be provided in the first dielectric layer 110 and the second opening 121 may also be provided in the second dielectric layer 120.

[0252] By providing a first opening 111 on the first dielectric layer 110 or a second opening 121 on the second dielectric layer 120, the thermal barrier of the dielectric layer can be reduced, the temperature sensitivity of the first thermistor NTC1 can be improved, and the temperature detection effect can be enhanced.

[0253] The temperature detection device 100 provided in this embodiment is an independent device, independent of the heat source to be measured, independent of the PCB, and independent of the processing unit. The application of the temperature detection device 100 in the electronic device 1 will be illustrated below.

[0254] Figure 22 is a partial schematic diagram of an electronic device provided in an embodiment of this application.

[0255] This application embodiment also provides an electronic device 1, as shown in FIG22. The electronic device 1 includes a temperature detection device 100 and a heat source 200 to be measured. The temperature detection device 100 and the heat source 200 to be measured are arranged adjacent to each other. The temperature detection device 100 includes any of the above-mentioned temperature detection devices.

[0256] When assembling the temperature sensing device 100 with the heat source 200 to be measured, the first dielectric layer 110 may face the heat source 200 to be measured, or the second dielectric layer 120 may face the heat source 200 to be measured. The embodiments of this application are only illustrated by the example of the first dielectric layer 110 facing the heat source 200 to be measured, and do not constitute a limitation on this application.

[0257] The temperature sensing device 100 and the heat source 200 to be measured are arranged adjacent to each other, as shown in Figure 22, where the temperature sensing device 100 is in contact with the heat source 200. For example, the temperature sensing device 100 is in direct contact with the heat source 200. Alternatively, for example, the temperature sensing device 100 is in indirect contact with the heat source 200. Optionally, the temperature sensing device 100 and the heat source 200 are bonded together with adhesive.

[0258] The temperature sensing device 100 and the heat source 200 to be measured are arranged adjacent to each other, or there may be an air gap between the temperature sensing device 100 and the heat source 200 to be measured.

[0259] The temperature sensing device 100 and the heat source to be measured 200 can be fixedly connected, for example by bonding, abutting, snapping, threaded connection, etc.

[0260] This application embodiment does not limit the specific structure of the heat source 200 to be tested in the electronic device 1. The heat source 200 to be tested can be any structure in the electronic device 1 whose temperature needs to be detected. For example, the heat source 200 to be tested can be a location on the display screen that is prone to heat generation, or a power device, solder pad, etc. in the electronic device 1. The heat source 200 to be tested can also be an assembly component assembled with the heat source to be tested. After assembling the heat source 200 to be tested with the heat source to be tested, the temperature detection device 100 is adjacent to the heat source to be tested. For example, as shown in FIG23, the heat source 200 to be tested can be a battery cover. The temperature detection device 100 is placed directly above the projection of the heat source to be tested (e.g., SOC). After assembling the battery cover with the heat source to be tested, the temperature detection device 100 is adjacent to the heat source to be tested.

[0261] In the electronic device 1 provided in this application embodiment, the temperature detection device 100 can be arranged adjacent to (e.g., in direct contact or contact with) any heat source 200 to be tested in the electronic device 1. The heat source 200 to be tested can be a heat source under test; the heat source 200 to be tested can also be an assembly assembled with the heat source under test. After assembling the heat source 200 to be tested with the heat source under test, the temperature detection device 100 is placed adjacent to the heat source under test. When the temperature of the heat source under test changes, it causes a change in the resistance of the temperature detection device 100, thereby obtaining a change in circuit voltage. Finally, the system reads the temperature change, realizing real-time detection of the temperature change of the structure under test. It is flexible in setting and has a wide range of applications.

[0262] Figure 24 is a partial schematic diagram of another electronic device provided in an embodiment of this application.

[0263] In some embodiments, as shown in FIG24, the electronic device 1 further includes a circuit board and a processing unit. The circuit board is connected to a first pin P1 and a second pin P2, and the processing unit is coupled to the first pin P1 and the second pin P2. For example, the processing unit is coupled to the circuit board, and the processing unit is coupled to the first pin P1 and the second pin P2 through the circuit board.

[0264] For example, a circuit board could be a PCB, a small board, or a power supply circuit board in electronic device 1.

[0265] The temperature detection device 100 in electronic device 1 can be set at any location in electronic device 1. It completes signal transmission through the circuit board and the processing unit, accurately detects real-time temperature changes, manages power consumption in the background, has flexible settings, and has a wide range of application scenarios.

[0266] Figure 25 is a schematic diagram of the fabrication process of a temperature detection device provided in an embodiment of this application.

[0267] This application also provides a method for fabricating a temperature sensing device, as shown in Figure 25. The method for fabricating the temperature sensing device includes:

[0268] S1, Forming the second dielectric layer 120.

[0269] S2. A first conductor layer 130, a first pin P1, and a second pin P2 are formed on one side of the second dielectric layer 120. The first conductor layer 130 includes a first thermistor NTC1, which is coupled between the first pin P1 and the second pin P2.

[0270] For example, step S2 includes:

[0271] S201, a thermistor film and a wire film are sequentially formed on one side of the second dielectric layer 120.

[0272] S202. Pattern the conductive film and the thermistor film to form a stacked pattern.

[0273] For example, exposure, development, and acid etching processes are used to pattern conductive films and thermistor films.

[0274] S203. Pattern the conductive film in the stacked pattern to expose part of the thermistor film as the first thermistor NTC1, and the first thermistor NTC1 is a thin film resistor.

[0275] For example, exposure, development, and alkaline etching processes are used to pattern the conductive film in the stacked pattern.

[0276] The fabrication process of the first thermistor NTC1 can be referred to the relevant description of the fabrication process of the first thermistor NTC1 in the flexible circuit board FPC in the above embodiments, and will not be repeated here.

[0277] S3. A first dielectric layer 110 is formed on the side of the first conductor layer 130 away from the second dielectric layer 120.

[0278] In this embodiment, the first pin P1 and the second pin P2 are exposed on the surface of the temperature sensing device 100. The first pin P1 and the second pin P2 may be located on the first conductor layer 130, or they may not be located on the first conductor layer 130. When the first pin P1 and the second pin P2 are not located on the first conductor layer 130, they can be obtained using methods described in related technologies. When the first pin P1 and the second pin P2 are located on the first conductor layer 30, they can be prepared using the same method as the first trace 31 described in the above embodiment.

[0279] The above are merely specific embodiments of this application, but the scope of protection of this application is not limited thereto. Any variations or substitutions within the technical scope disclosed in this application should be included within the scope of protection of this application. Therefore, the scope of protection of this application should be determined by the scope of the claims.

Claims

1. A flexible circuit board, characterized by, The flexible circuit board includes: A first flexible dielectric layer and a second flexible dielectric layer are stacked together; The first pin, the second pin, the third pin, and the fourth pin are all exposed on the surface of the flexible circuit board. The first trace and the first thermistor are both disposed between the first flexible dielectric layer and the second flexible dielectric layer; the first thermistor is coupled between the first pin and the second pin, and the first thermistor is a thin film resistor; the first trace and the first thermistor are disposed at intervals, and the first trace is coupled between the third pin and the fourth pin.

2. The flexible circuit board of claim 1, wherein, The flexible circuit board includes a second trace, and the first thermistor is located on the second trace. The first thermistor is coupled between the first pin and the second pin through the second trace.

3. The flexible circuit board of claim 2, wherein, The flexible circuit board includes a plurality of first thermistors, which are connected in series between the first pin and the second pin.

4. The flexible circuit board of claim 3, wherein, The spacing between adjacent first thermistors is d, where 0.05mm ≤ d ≤ 2mm.

5. The flexible circuit board according to claim 3 or 4, characterized in that, The first thermistor is directly coupled to the first pin and the second pin.

6. The flexible circuit board according to any one of claims 1 to 5, wherein, The first trace and the first thermistor are arranged on the same layer.

7. The flexible circuit board according to any one of claims 1 to 6, wherein, The flexible circuit board further includes a first resistor, which is disposed on the side of the second flexible dielectric layer away from the first thermistor. The flexible circuit board further includes a fifth pin exposed on the surface of the flexible circuit board, and a first resistor is coupled between the fifth pin and the first pin, wherein the first resistor is a thin-film resistor.

8. The flexible circuit board of claim 7, wherein, The flexible circuit board also includes a capacitor, which is connected in parallel with the first thermistor between the first pin and the second pin.

9. The flexible circuit board according to any one of claims 1 to 6, wherein, The flexible circuit board also includes a sixth pin and a Wheatstone bridge; The sixth pin is exposed on the surface of the flexible circuit board; The Wheatstone bridge includes a first input terminal, a second input terminal, a first output terminal, a second output terminal, a first thermistor, and a plurality of second resistors; the first input terminal and the second input terminal are coupled to the sixth pin, the first output terminal is coupled to the first pin, the second output terminal is coupled to the second pin, and the second resistors are thin-film resistors.

10. The flexible circuit board of claim 9, wherein, The flexible circuit board also includes a third resistor and a seventh pin; The seventh pin is exposed on the surface of the flexible circuit board; the third resistor is coupled between the seventh pin and the first input terminal.

11. A circuit board assembly, characterized by The circuit board assembly includes a rigid circuit board, a flexible circuit board, and a processing unit. The flexible circuit board includes the flexible circuit board according to any one of claims 1-5 or 8. The first pin is connected to the rigid circuit board, and the processing unit is coupled to the first pin.

12. The circuit board assembly of claim 11, wherein, The circuit board assembly also includes a first resistor, which is coupled to the first pin.

13. The circuit board assembly of claim 12, wherein, The circuit board assembly also includes a capacitor, which is coupled in parallel with the first thermistor.

14. The circuit board assembly of claim 13, wherein, The circuit board assembly also includes a third resistor, which is coupled to the first input terminal.

15. An electronic device, comprising: The electronic device includes a circuit board assembly and a housing, the circuit board assembly being disposed within the housing, and the circuit board assembly comprising the circuit board assembly according to any one of claims 11-14.

16. A temperature detecting device, characterized by comprising: The temperature sensing device includes: A first dielectric layer and a second dielectric layer are stacked together; A first pin and a second pin, the first pin and the second pin being exposed on the surface of the temperature sensing device; A first conductor layer is disposed between the first dielectric layer and the second dielectric layer; the first conductor layer includes a first thermistor, which is coupled between the first pin and the second pin, and the first thermistor is a thin-film resistor.

17. The temperature detecting device according to claim 16, wherein The first conductor layer includes a plurality of first thermistors, which are connected in series between the first pin and the second pin.

18. The temperature detecting device according to claim 17, wherein The spacing between adjacent first thermistors is d, where 0.1mm ≤ d ≤ 2mm.

19. The temperature detecting device according to claim 16, wherein The temperature sensing device further includes a second conductor layer, which is disposed on the side of the second dielectric layer away from the first conductor layer; the second conductor layer includes a first resistor. The temperature sensing device further includes a fifth pin; the first resistor is coupled between the fifth pin and the first pin, and the first resistor is a thin-film resistor.

20. The temperature detecting device according to claim 19, wherein The temperature sensing device further includes a capacitor, which is connected in parallel with the first thermistor between the first pin and the second pin.

21. The temperature detecting device according to claim 16, wherein The temperature sensing device further includes a third conductor layer and a Wheatstone bridge, the third conductor layer being disposed on the side of the second dielectric layer away from the first conductor layer; the temperature sensing device further includes a sixth pin, the sixth pin being exposed on the surface of the temperature sensing device; The Wheatstone bridge includes a first input terminal, a second input terminal, a first output terminal, a second output terminal, a first thermistor, and a plurality of second resistors; the first input terminal and the second input terminal are coupled to the sixth pin, the first output terminal is coupled to the first pin, the second output terminal is coupled to the second pin, and the second resistors are located in the first conductor layer or the third conductor layer, and the second resistors are thin-film resistors.

22. The temperature detecting device according to claim 21, wherein The temperature sensing device also includes a third resistor and a seventh pin; The seventh pin is exposed on the surface of the temperature sensing device; the third resistor is coupled between the seventh pin and the first input terminal.

23. The temperature sensing device according to any one of claims 16-22, characterized in that, The first dielectric layer includes a first opening, which is offset from the first thermistor; or, The second dielectric layer includes a second opening, which is offset from the first thermistor.

24. The temperature detecting device according to any one of claims 16 to 23, wherein The first conductor layer also includes a second thermistor, an eighth pin, and a ninth pin; The second thermistor is spaced apart from the first thermistor, the eighth pin and the ninth pin are exposed on the surface of the temperature sensing device, the second thermistor is coupled between the eighth pin and the ninth pin, and the second thermistor is a thin film resistor.

25. An electronic device, comprising: The electronic device comprises a temperature detecting device, a heat source to be measured and a processing unit, the temperature detecting device and the heat source to be measured are arranged adjacently, the processing unit is coupled with the first pin and the second pin, and the temperature detecting device comprises the temperature detecting device according to any one of claims 16-24.

26. The electronic device of claim 25, wherein, The temperature detecting device is in contact with the heat source to be measured.

27. The electronic device of claim 25 or 26, wherein, The electronic device further comprises a circuit board, and the circuit board is keyed with the first pin and the second pin.

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