Circuit board and preparation method thereof, circuit board assembly and electronic equipment

Abstract

The embodiment of the invention provides a circuit board and a preparation method thereof, a circuit board assembly and electronic equipment, relates to the technical field of electronics, and is used for detecting the temperature of a position needing to be detected in real time. The thermistor is integrated in the circuit board, the temperature change at the position of the thermistor is detected according to the change condition of the resistance value of the thermistor along with the temperature, and an additional processing unit is not needed. The thermistors can be flexibly arranged so as to detect the temperature of various to-be-detected positions in real time. For example, if the temperature of the welding spot of the semiconductor device connected with the circuit board needs to be detected, the temperature of the welding spot of the semiconductor device can be directly tested by taking the first conductive part coupled with the thermistor as a bonding pad connected with the semiconductor device. For example, if the temperature of a certain position on the circuit board needs to be detected, the first conductive part coupled with the thermistor is coupled with a power supply on the circuit board, and the thermistor is arranged at a position to be subjected to temperature measurement, so that the temperature of a target position can be directly tested.

Description

[0001] The present application claims priority from the Chinese patent application No. 202410504788.3 filed on April 24, 2024 with the State Intellectual Property Office, and titled "Circuit board and preparation method thereof, circuit board assembly, and electronic device", the content of which is incorporated herein by reference in its entirety. TECHNICAL FIELD

[0002] The present application relates to the technical field of electronics, and in particular to a circuit board and a preparation method thereof, a circuit board assembly, and an electronic device. BACKGROUND

[0003] With the development of electronic technology, the functions of electronic devices are constantly enriched and comprehensive, and the processing capabilities of semiconductor devices such as chips and power devices in electronic devices are constantly improved.

[0004] The phenomenon of heat generation during the operation of semiconductor devices is currently unavoidable, which leads to an overall temperature rise around the semiconductor devices. On the one hand, the materials of the semiconductor devices, the materials of the circuit boards carrying the semiconductor devices, and the materials of the solder joints connecting the semiconductor devices and the PCBs are different, and the coefficients of thermal expansion (CTE) between the multiple materials usually do not match, which leads to the exacerbation of solder joint fatigue creep (crack formation). Long-term use will cause the crack to expand and eventually fail. On the other hand, for temperature-sensitive devices, if the temperature at the location is too high, it will directly affect the performance of the temperature-sensitive devices.

[0005] Therefore, if the temperature at the required detection position can be accurately detected in real time, reasonable thermal management and solder joint thermal fatigue life prediction can be effectively performed. SUMMARY

[0006] The present application provides a circuit board and a preparation method thereof, a circuit board assembly, and an electronic device, for accurately detecting the temperature at the required detection position in real time.

[0007] To achieve the above-mentioned purpose, the present application adopts the following technical solutions:

[0008] In a first aspect, the present application provides a circuit board, comprising: a first conductor layer, a first dielectric layer, at least one second conductor layer, at least one second dielectric layer, and a Wheatstone bridge integrated in the first conductor layer and the second conductor layer. The first conductor layer comprises a first conductive part, a second conductive part, and a third conductive part, and the first dielectric layer covers the first conductor layer, exposing the second conductive part and the third conductive part. The at least one second conductor layer and the at least one second dielectric layer are alternately arranged on a side of the first conductor layer away from the first dielectric layer. The Wheatstone bridge comprises a first input terminal, a second input terminal, a first output terminal, a second output terminal, and a plurality of resistors. The resistors are located in the first conductor layer or the second conductor layer, the plurality of resistors comprise one or more thermistors, the first input terminal and the second input terminal are coupled to the first conductive part, the first output terminal is coupled to the second conductive part, and the second output terminal is coupled to the third conductive part.

[0009] The circuit board provided by the present application integrates the Wheatstone bridge containing the thermistor inside the circuit board, detects the temperature change at the position of the thermistor through the change of the resistance value of the thermistor with temperature, and does not need an additional processing unit. The Wheatstone bridge can be flexibly arranged to detect the temperature of various to-be-detected positions in real time. Moreover, the first conductive part is used as a to-be-detected heat source directly or is used to be connected to a to-be-detected heat source, and the Wheatstone bridge is directly coupled to the first conductive part. Therefore, the temperature change on the first conductive part can be directly transmitted to the thermistor of the Wheatstone bridge, which is equivalent to that the thermistor can directly sense the temperature change of the to-be-detected heat source, thereby realizing close-range, rapid, and direct detection of the temperature of the to-be-detected heat source. For example, if the temperature of the solder joint of a semiconductor device connected to the circuit board needs to be detected, the first conductive part coupled to the Wheatstone bridge is used as a pad connected to the solder joint of the semiconductor device, and the temperature of the solder joint is directly transmitted to the thermistor, so that the temperature of the solder joint of the semiconductor device can be directly detected, and the detection precision can reach within ±0.5℃.

[0010] In a possible implementation, the thermistor is located in the first conductor layer. The thermistor is located in the first conductor layer, and the first conductive part is also located in the first conductor layer, so that the distance between the thermistor and the first conductive part can be shortened, and the thermistor can accurately feed back the temperature condition of the first conductive part, thereby improving the detection precision.

[0011] In a possible implementation, the plurality of resistors further comprise a plurality of non-thermistor resistors, and the plurality of non-thermistor resistors are located in the at least one second conductor layer. By layering the thermistors and the non-thermistor resistors, the preparation process of the Wheatstone bridge can be simplified.

[0012] In a possible implementation, at least one of the plurality of resistors in the Wheatstone bridge is a thin-film resistor. Compared with a Wheatstone bridge formed by soldering resistor components, a Wheatstone bridge formed by thin-film resistors can reduce the area occupied by the Wheatstone bridge.

[0013] In a possible implementation, the first conductor layer includes a first wire layer and a first resistor layer, and the first resistor layer includes a thermistor; the resistivity of the material of the first wire layer is less than the resistivity of the material of the first resistor layer. This is a simple structure implementation.

[0014] In a possible implementation, the first wire layer is arranged on the surface of the first resistor layer facing away from the second dielectric layer, and the first wire layer has a first opening, and the part of the first resistor layer corresponding to the first opening serves as the thermistor. In this way, in the process of manufacturing the first conductor layer, the first wire layer and the first resistor layer can be processed synchronously in some processes, simplifying the manufacturing process. Moreover, the first resistor layer is located below the first wire layer, and does not affect the transmission of signals in the first wire layer.

[0015] In a possible implementation, the thickness of the first resistor layer is 10 nm to 1000 nm. Because the space in the circuit board is limited, if the thickness of the first resistor layer is too thin, the resistance made in the limited space cannot meet the detection requirements. If the thickness of the first resistor layer is too thick, it will affect the punching quality, the thickness of the circuit board, and the like.

[0016] In a possible implementation, the at least one second conductor layer includes a second wire layer and a second resistor layer, and the second resistor layer includes a non-thermistor; the resistivity of the material of the second wire layer is less than the resistivity of the material of the second resistor layer. This is a simple structure implementation.

[0017] In a possible implementation, the second wire layer is arranged on the surface of the second resistor layer facing the first conductor layer, and the second wire layer has a second opening, and the part of the second resistor layer corresponding to the second opening serves as the non-thermistor. In this way, in the process of manufacturing the second conductor layer, the second wire layer and the second resistor layer can be processed synchronously in some processes, simplifying the manufacturing process. Moreover, the second resistor layer is located below the second wire layer, and does not affect the transmission of signals in the second wire layer.

[0018] In a possible implementation, the thickness of the second resistor layer is 10 nm to 1000 nm. Because the space in the circuit board is limited, if the thickness of the second resistor layer is too thin, the resistance made in the limited space cannot meet the detection requirements. If the thickness of the second resistor layer is too thick, it will affect the punching quality, the thickness of the circuit board, and the like.

[0019] In a possible implementation, the plurality of resistors includes a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor, and a sixth resistor, the fourth resistor and the sixth resistor are thermistors; one end of the first resistor is coupled to the first input terminal, and the other end of the first resistor is coupled to the first output terminal; one end of the second resistor is coupled to the first input terminal, and the other end of the second resistor is coupled to the second output terminal; one end of the third resistor is coupled to the first output terminal, and the other end of the third resistor is coupled to the second output terminal; one end of the fourth resistor is coupled to the first output terminal, and the other end of the fourth resistor is coupled to one end of the fifth resistor; the other end of the fifth resistor is coupled to one end of the sixth resistor, and the other end of the sixth resistor is coupled to the second output terminal. Due to the requirement of low power consumption, the center value of the thermistor in the Wheatstone bridge needs to be large. However, due to various factors, the center value of a thermistor cannot be made very large. However, by changing the topology design of the Wheatstone bridge and arranging two series-connected thermistors in the Wheatstone bridge, it can be equivalent to arranging a thermistor with a large center value in the Wheatstone bridge. Moreover, the two thermistors detect the temperatures at two positions, and compared with the Wheatstone bridge with two single thermistors, the Wheatstone bridge with two thermistors has a smaller total number of resistors and occupies a smaller area.

[0020] In a possible implementation, the plurality of resistors includes a seventh resistor, an eighth resistor, a ninth resistor, and a tenth resistor, one of the seventh resistor, the eighth resistor, the ninth resistor, and the tenth resistor is a thermistor; one end of the seventh resistor is coupled to the first input terminal, and the other end of the seventh resistor is coupled to the first output terminal; one end of the eighth resistor is coupled to the first input terminal, and the other end of the eighth resistor is coupled to the second output terminal; one end of the ninth resistor is coupled to the first output terminal, and the other end of the ninth resistor is coupled to the second input terminal; one end of the tenth resistor is coupled to the second output terminal, and the other end of the tenth resistor is coupled to the second input terminal. This is a simple implementation.

[0021] In a possible implementation, the temperature change rate of the thermistor is greater than or equal to 2Ω / ℃. By limiting the temperature change rate of the thermistor to be greater than or equal to 2Ω / ℃, the feedback voltage output by the Wheatstone bridge is easy to collect, the precision requirement of the collection device can be reduced, and the cost can be reduced.

[0022] In a possible implementation, the square resistance of the thermistor is 200Ω-3000Ω. If the square resistance of the resistor is too small, more wiring resources are needed to obtain the target thin-film resistor center value. If the center value of the thermistor is too small, the resistance change caused by the temperature change of the thermistor will be small, the current change on the thermistor will not be obvious, and the temperature detection accuracy will be affected. If the square resistance of the resistor is too large, it is not easy to achieve a high resistance temperature coefficient. Similarly, the ratio of the resistance change caused by the temperature change to the total resistance decreases, and the detectable change voltage is smaller, which is not conducive to obtaining an accurate temperature change value.

[0023] In a possible implementation, the center resistance of the thermistor is 200Ω-3000Ω. The voltage output by the first output end and the second output end of the Wheatstone bridge can reflect the change of the resistance of the thermistor, and the output voltage is positively correlated with the center resistance of the resistance. Therefore, when the center resistance of the resistance is too small, the temperature change of the thermistor is relatively small, the current change on the thermistor is not obvious, the output voltage is too small, and the temperature detection accuracy is affected. When the center resistance of the resistance is too large, the area of the resistance needs to be increased, which occupies too many wiring resources and is not conducive to the integration of the Wheatstone bridge on the circuit board.

[0024] In a possible implementation, the distance from the thermistor to the first conductive part is 5μm-1mm. In some technologies, a thermistor is attached beside a device to be measured on a circuit board to detect the temperature of the device to be measured through the thermistor. Because of the characteristics of the thermistor itself, the thermistor needs to be at least 3mm-5mm away from the device to be measured to measure the accurate temperature. The thin-film resistance used in the present application can read the instantaneous temperature change and will not deviate from the result due to the dramatic change of the temperature, so the distance from the thermistor to the first conductive part can be 5μm-1mm. Therefore, the scheme of the present application can improve the detection accuracy and also achieve the purpose of product miniaturization.

[0025] In a possible implementation, the circuit board further includes an eleventh resistance coupled with the first input end. By setting the eleventh resistance in series with the Wheatstone bridge, an upper pull resistance is set, and the series resistance value of the eleventh resistance and the Wheatstone bridge can be increased to reduce the power consumption of the detection circuit.

[0026] In a second aspect of the present application, a circuit board assembly is provided, which includes a processing unit, a circuit board, and a heat source to be measured. The circuit board includes the circuit board of any one of the first aspect. The processing unit is coupled with the second conductive part and the third conductive part, respectively. The heat source to be measured is connected with the first conductive part, or the first conductive part serves as the heat source to be measured.

[0027] In a possible implementation, the circuit board assembly further includes a backend circuit coupled with the first conductive part. The backend circuit is coupled with the Wheatstone bridge in parallel, which can reduce the influence of the Wheatstone bridge on the power consumption of the backend circuit.

[0028] In a possible implementation, the circuit board assembly further includes a backend circuit coupled with the Wheatstone bridge of the circuit board. The backend circuit is coupled with the Wheatstone bridge in series, and the temperature at the position to be measured can still be obtained.

[0029] In a possible implementation, the circuit board assembly further includes an excitation source, and the excitation source is coupled with the first conductive part. By coupling the first conductive part with the excitation source, the Wheatstone bridge can be placed at any position where the temperature needs to be detected, and the temperature at the position where the Wheatstone bridge is arranged can be directly and accurately measured.

[0030] In a third aspect, the embodiment of the present application provides a circuit board assembly, including a processing unit, a circuit board, and a heat source to be detected; the circuit board includes a first conductive part, a second conductive part, and a first dielectric layer, a first conductor layer, and a second dielectric layer arranged in sequence; the first conductor layer includes a thermistor, the thermistor is coupled between the first conductive part and the second conductive part, and the thermistor is a thin-film resistor; the processing unit is coupled with the first conductive part or the second conductive part; the first conductive part is connected with the heat source to be detected; or the first conductive part serves as the heat source to be detected.

[0031] The circuit board assembly provided by the embodiment of the present application integrates the thermistor in the circuit board, detects the temperature change at the position of the thermistor by the change of the resistance value of the thermistor with the temperature, and does not need an additional processing unit. The thermistor can be flexibly arranged to detect the temperature of various positions to be detected in real time. Moreover, the first conductive part is directly used as the heat source to be detected or the first conductive part is connected with the heat source to be detected, and the thermistor is directly coupled with the first conductive part. Therefore, the temperature change on the first conductive part can be directly transmitted to the thermistor, and the thermistor can directly sense the temperature change of the heat source to be detected, so that the temperature of the heat source to be detected can be detected in a close distance, quickly and directly.

[0032] In a possible implementation, the circuit board further includes a first resistor and a second conductor layer, the second conductor layer is arranged on a side of the second dielectric layer away from the first conductor layer, the first resistor is located in the second conductor layer, and the first resistor and the processing unit are coupled with a same conductive part of the first conductive part and the second conductive part. By arranging the first resistor in series with the thermistor, an upper pull resistor is arranged, and the series resistance value of the first resistor and the thermistor can be increased to reduce the power consumption of the detection circuit.

[0033] In a possible implementation, the circuit board assembly further includes a capacitor, and the capacitor is coupled in parallel with the thermistor. By arranging the capacitor in parallel with the thermistor, a filter can be formed to improve the temperature sensing accuracy.

[0034] In a fourth aspect, the embodiment of the present application provides an electronic device, including a circuit board assembly and a middle frame, and the circuit board assembly is arranged on the middle frame; the circuit board assembly includes the circuit board assembly of the second aspect.

[0035] In a fifth aspect, the present application provides a method for manufacturing a circuit board, the circuit board comprising a Wheatstone bridge; the method comprising: forming at least one second conductor layer and at least one second dielectric layer; the at least one second conductor layer and the at least one second dielectric layer being arranged alternately; forming a first conductor layer, the first conductor layer being located on a side of the second dielectric layer away from the second conductor layer; the first conductor layer comprising a first conductive part, a second conductive part, and a third conductive part; forming a first dielectric layer, the first dielectric layer covering the first conductor layer, and exposing the second conductive part and the third conductive part; wherein the Wheatstone bridge comprises a first input terminal, a second input terminal, a first output terminal, a second output terminal, and a plurality of resistors; the resistors being located on the first conductor layer or the second conductor layer; the plurality of resistors comprising one or more thermistors; the first input terminal and the second input terminal being coupled to the first conductive part; the first output terminal being coupled to the second conductive part; and the second output terminal being coupled to the third conductive part.

[0036] In a possible implementation, forming the first conductor layer comprises: sequentially forming a first resistor film and a first wire film on a surface of the second dielectric layer away from the second conductor layer; patterning the first wire film and the first resistor film to form a first wire film pattern and a first resistor layer; and patterning the first wire film pattern to expose part of the first resistor layer, thereby forming a first wire layer. This is a simple implementation.

[0037] In a possible implementation, patterning the first wire film and the first resistor film comprises: patterning the first wire film and the first resistor film by using an exposure, development, and acid etching process.

[0038] In a possible implementation, patterning the first wire film pattern comprises: patterning the first wire film pattern by using an exposure, development, and alkaline etching process. BRIEF DESCRIPTION OF DRAWINGS

[0039] Figure 1 A schematic diagram of an electronic device according to an embodiment of the present application is shown in FIG. 1;

[0040] Figure 2 A schematic diagram of a temperature detection scheme according to an embodiment of the present application is shown in FIG. 2;

[0041] Figure 3 A schematic diagram of a PCB according to an embodiment of the present application is shown in FIG. 3;

[0042] Figure 4A and Figure 4B A schematic diagram of a Wheatstone bridge according to an embodiment of the present application is shown in FIG. 4;

[0043] Figure 5A and Figure 5B A schematic diagram of a PCB according to an embodiment of the present application is shown in FIG. 3;

[0044] Figure 5C and Figure 5D A disassembled view of a PCB provided for an embodiment of the present application;

[0045] Figure 6A A topological schematic diagram of a detection circuit in a circuit board provided for an embodiment of the present application;

[0046] Figure 6B A structural schematic diagram of a PCB provided for an embodiment of the present application;

[0047] Figure 7 A flowchart of a preparation method of a circuit board provided for an embodiment of the present application;

[0048] Figures 8A-10 A preparation process schematic diagram of a circuit board provided for an embodiment of the present application;

[0049] Figure 11 A structural schematic diagram of a circuit board assembly provided for an embodiment of the present application;

[0050] Figure 12 A structural schematic diagram of a circuit board assembly provided for an embodiment of the present application;

[0051] Figure 13 A structural schematic diagram of a circuit board assembly provided for an embodiment of the present application;

[0052] Figure 14 A structural schematic diagram of a circuit board assembly provided for an embodiment of the present application;

[0053] Figure 15 A layout schematic diagram of a first conductor layer provided for an embodiment of the present application;

[0054] Figure 16A and Figure 16B A structural schematic diagram of a circuit board assembly provided for an embodiment of the present application;

[0055] Figure 17A A topological schematic diagram of a detection circuit provided for an embodiment of the present application;

[0056] Figure 17B A structural schematic diagram of a circuit board assembly provided for an embodiment of the present application;

[0057] Figure 18A A topological schematic diagram of a detection circuit provided for an embodiment of the present application;

[0058] Figure 18B A structural schematic diagram of a circuit board assembly provided for an embodiment of the present application;

[0059] Figure 19A and Figure 19B A schematic structural diagram of a circuit board assembly provided in an embodiment of the present application;

[0060] Figure 20A A topological diagram of a detection circuit provided in an embodiment of the present application;

[0061] Figure 20B A schematic structural diagram of a circuit board assembly provided in an embodiment of the present application;

[0062] Figure 21A A topological diagram of a detection circuit provided in an embodiment of the present application;

[0063] Figure 21B A schematic structural diagram of a circuit board assembly provided in an embodiment of the present application. DETAILED DESCRIPTION

[0064] The technical solutions in the embodiments of the present application will be described below in conjunction with the drawings in the embodiments of the present application. Obviously, the described embodiments are only part of the embodiments of the present application, rather than all the embodiments.

[0065] 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 the technical features being referred to. Thus, a feature qualified as "second," "first," etc., may explicitly or implicitly include one or more of such features. In the description of this application, unless otherwise specified, "plurality" means two or more.

[0066] In addition, in the embodiments of the present application, directional terms such as "up", "down", "left", and "right" may be defined including but not limited to the orientation relative to the schematic placement of the components in the drawings. It should be understood that these directional terms may be relative concepts, which are used for relative descriptions and clarifications, and may change accordingly according to changes in the orientation of the components in the drawings.

[0067] In the embodiments of this application, unless otherwise specified or limited, the term "connection" should be understood in a broad sense. For example, "connection" can mean fixed connection, detachable connection, or integration; it can mean direct connection or indirect connection through an intermediate medium. In addition, the term "coupling" can mean direct electrical connection or indirect electrical connection through an intermediate medium. The term "contact" can mean direct contact or indirect contact through an intermediate medium.

[0068] In the embodiments of the present application, "and / or" describes the relationship between associated objects, indicating that three possible relationships exist. For example, "A and / or B" can represent: A exists alone, A and B exist simultaneously, and B exists alone. A and B can be singular or plural. The character " / " generally indicates that the associated objects are in an "or" relationship.

[0069] An embodiment of the present application provides an electronic device, which may be, for example, a foldable electronic device. The electronic device may be, for example, a consumer electronic product, a home electronic product, a vehicle-mounted electronic product, or a financial electronic product. Among them, consumer electronic products include mobile phones, tablet computers, laptop computers, e-readers, personal computers (PCs), personal digital assistants (PDAs), desktop displays, smart wearable products (for example, smart watches, smart bracelets), virtual reality (VR) electronic devices, augmented reality (AR) electronic devices, drones, etc. Home electronic products include smart door locks, televisions, refrigerators, rechargeable small household appliances (for example, soymilk machines, sweeping robots), etc. Vehicle-mounted electronic products include car navigation systems, car DVDs, etc. Financial electronic products include ATM machines, electronic devices for self-service transactions, etc.

[0070] The embodiments of the present application do not impose any special restrictions on the specific form of the above-mentioned electronic device. For the convenience of explanation, the following embodiments are all illustrated by taking the electronic device as a mobile phone.

[0071] Figure 1 This is an architectural diagram of an electronic device provided in an embodiment of the present application.

[0072] Taking the electronic device provided in the embodiment of the present application as a mobile phone as an example, for example, Figure 1 As shown, the electronic device 1 mainly includes a display module 2, a middle frame 3, a housing (or battery cover, rear housing) 4 and a cover plate 5.

[0073] The display module 2 has a light-emitting side through which a display image can be seen and a back side arranged 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 arranged on the light-emitting side of the display module 2 .

[0074] The display module 2 includes a display panel (DP). In a possible embodiment of the present 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 further includes a back light unit (BLU) located at the back of the liquid crystal display (away from the side of the LCD used for displaying images). The back light unit can provide a light source for the liquid crystal display, so that each sub pixel in the liquid crystal display can emit light to realize image display.

[0075] In another possible embodiment of the present application, the display module 2 is an organic light emitting diode display module. In this case, the display panel is an organic light emitting diode (OLED) display panel. Since an electroluminescent layer is arranged in each sub pixel of the OLED display panel, the OLED display panel can realize self-emission after receiving a working voltage. In this case, the display module 2 with the OLED display panel does not need to be provided with the back light unit.

[0076] 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 a cover glass (CG) for example, which can have a certain toughness.

[0077] The middle frame 3 is located between the display module 2 and the shell 4. The surface of the middle frame 3 away from the display module 2 is used to mount internal components such as a battery, a printed circuit board (PCB), a camera, an antenna and the like. After the shell 4 is covered with the middle frame 3, the internal components are located between the shell 4 and the middle frame 3.

[0078] The electronic device 1 further includes semiconductor devices such as a main board, a system on chip (SOC), a power management unit (PMU), a radio frequency integrated circuit (RFIC) and the like arranged on the PCB. The PCB is used to carry the semiconductor devices and complete signal interaction with the semiconductor devices.

[0079] The phenomenon of heat generation during the operation of a semiconductor device is currently unavoidable, resulting in an overall temperature rise around the semiconductor device. On the one hand, the materials of the semiconductor device, the materials of the circuit board carrying the semiconductor device, and the materials of the solder joints connecting the semiconductor device and the PCB are different, and the coefficients of thermal expansion (CTE) between multiple materials usually do not match, resulting in the exacerbation of solder joint fatigue creep (crack formation). Long-term use can cause the crack to expand and eventually fail. On the other hand, for temperature-sensitive devices, if the temperature at the location is too high, it will directly affect the performance of the temperature-sensitive device. Therefore, if the temperature at the required detection location can be accurately monitored in real time, reasonable thermal management and solder joint thermal fatigue life estimation can be effectively performed.

[0080] Figure 2 A schematic diagram of a temperature detection scheme provided by an embodiment of the present application.

[0081] In some technologies, as shown in Figure 2 for a SOC chip, by setting a negative temperature coefficient (NTC) circuit inside the SOC, the temperatures of different regions of the silicon wafer are detected, and the temperatures of the corresponding solder joint regions are calculated through steady-state thermal simulation. However, only the temperature of the region where the NTC circuit is provided inside the chip can be obtained, and the temperature of the solder joint region is calculated through software, and the temperature detection of the precise position of the solder joint cannot be realized.

[0082] In some technologies, as shown in Figure 2 for a high-power device (such as a PMU, RFIC), by welding an NTC resistor next to the circuit on the surface of the PCB, the temperature of the region next to the high-power device is obtained. The solder joint temperature cannot be directly transmitted to the NTC resistor, and only the region temperature can be indirectly tested.

[0083] Based on this, the current temperature detection technology can obtain the temperature of the region near the solder joint, but cannot directly measure the temperature at the solder joint.

[0084] An embodiment of the present application provides a temperature detection technology, which can directly measure the real-time temperature at the solder joint.

[0085] Figure 3 A structure schematic diagram of a PCB provided by an embodiment of the present application.

[0086] An embodiment of the present application provides a circuit board, for example, a PCB. As shown in Figure 3 the PCB includes a first conductor layer 10, a first dielectric layer 20, at least one second conductor layer 30, at least one second dielectric layer 40, and a Wheatstone bridge 50.

[0087] The first conductor layer 10 includes a first conductive part 11, a second conductive part 12, and a third conductive part 13, which are used to couple with external devices. The embodiments of the present application do not limit the shape and arrangement position of the first conductive part 11, the second conductive part 12, and the third conductive part 13, Figure 3 The material of the first conductor layer 10 includes copper (Cu) for example. Of course, the embodiments of the present application do not limit that the first conductor layer 10 only includes the first conductive part 11, the second conductive part 12, and the third conductive part 13. The first conductor layer 10 can also include other conductive parts.

[0088] For example, the PCB is a hard circuit board, and the first conductive part 11, the second conductive part 12, and the third conductive part 13 can all be pads. The Wheatstone bridge 50 is used to detect the heat generation of the pads at the pad positions.

[0089] For another example, the PCB is a soft circuit board, the first conductive part 11 can be a trace, and the second conductive part 12 and the third conductive part 13 can be pads. The Wheatstone bridge 50 is used to detect the heat generation of the trace at a certain position of the trace.

[0090] The first dielectric layer 20 covers the first conductor layer 10, and the first dielectric layer 20 exposes the second conductive part 12 and the third conductive part 13. For example, the first dielectric layer 20 is a surface layer of the PCB. The first dielectric layer 20 can expose the first conductive part 11, or the first dielectric layer 20 can not expose the first conductive part 11, Figure 3 The first dielectric layer 20 exposes the first conductive part 11 is taken as an example for illustration.

[0091] For example, the PCB is a hard circuit board, and the material of the first dielectric layer 20 is solder resist ink.

[0092] For another example, the PCB is a soft circuit board, and the material of the first dielectric layer 20 is a coverlay.

[0093] At least one second conductor layer 30 and at least one second dielectric layer 40 are arranged alternately on the side of the first conductor layer 10 away from the first dielectric layer 20. For example, the side of the first conductor layer 10 away from the first dielectric layer 20 is sequentially provided with a second dielectric layer 40, a second conductor layer 30, a second dielectric layer 40, a second conductor layer 30, and a second dielectric layer 40. The second dielectric layer 40 farthest away from the first dielectric layer 20 is another surface layer of the PCB. The embodiments of the present application do not limit the number of the second conductor layer 30 and the second dielectric layer 40 included in the PCB, Figure 3 The above is only one example for illustration.

[0094] For example, the PCB is a hard circuit board, and the material of the second dielectric layer 40 is a prepreg.

[0095] Or in an example, the PCB is a flexible printed circuit board, and the material of the second dielectric layer 40 is polyimide (PI).

[0096] The Wheatstone bridge 50 includes a first input terminal I1, a second input terminal I2, a first output terminal O1, and a second output terminal O2. The first input terminal I1 and the second input terminal I2 are coupled to the first conductive part 11, the first output terminal O1 is coupled to the second conductive part 12, and the second output terminal O2 is coupled to the third conductive part 13. The first input terminal I1, the second input terminal I2, the first output terminal O1, and the second output terminal O2 can be located in the first conductor layer 10 or the second conductor layer 30, for example.

[0097] The embodiments of the present application do not limit the structure of the Wheatstone bridge 50, and the Wheatstone bridge 50 in the related art is applicable to the embodiments of the present application.

[0098] In some embodiments, the Wheatstone bridge 50 further includes a plurality of resistors, and the resistors are located in the first conductor layer 10 or the second conductor layer 30. For example, part of the plurality of resistors are located in the first conductor layer 10, and part of the plurality of resistors are located in the second conductor layer 30. Alternatively, all of the plurality of resistors are located in the first conductor layer 10, or all of the plurality of resistors are located in the second conductor layer 30.

[0099] The plurality of resistors include one or more thermistors.

[0100] A thermistor is a sensor resistor whose resistance value changes with temperature. According to different temperature coefficients, it is divided into a positive temperature coefficient thermistor (PTC thermistor) and a negative temperature coefficient thermistor (NTC thermistor). The resistance value of the positive temperature coefficient thermistor increases with the increase of temperature, and the resistance value of the negative temperature coefficient thermistor decreases with the increase of temperature. The thermistors included in the Wheatstone bridge 50 in the embodiments of the present application can be positive temperature coefficient thermistors or negative temperature coefficient thermistors.

[0101] The Wheatstone bridge 50 is used to find an unknown resistance very accurately by comparing the unknown resistance with a known resistance value. In the Wheatstone bridge 50, a null or balanced condition is used to find the unknown resistance.

[0102] The PCB provided by the embodiments of the present application has a Wheatstone bridge 50 integrated inside the PCB and containing a thermistor. The Wheatstone bridge 50 detects the temperature change at the position of the thermistor by the change of the resistance value of the thermistor with temperature, and does not need an additional processing unit. The Wheatstone bridge 50 can be flexibly arranged to detect the temperature of various to-be-detected positions in real time. Moreover, the first conductive part 11 is directly used as a to-be-detected heat source or the first conductive part 11 is used in connection with a to-be-detected heat source, and the Wheatstone bridge 50 is directly coupled with the first conductive part 11. Therefore, the temperature change on the first conductive part 11 can be directly transmitted to the thermistor of the Wheatstone bridge 50, which is equivalent to that the thermistor can directly sense the temperature change of the to-be-detected heat source, thereby realizing close-range, rapid and direct detection of the temperature of the to-be-detected heat source. For example, if the temperature of a solder joint of a semiconductor device connected with the PCB needs to be detected, the first conductive part 11 coupled with the Wheatstone bridge 50 is used as a pad connected with the solder joint of the semiconductor device, and the temperature of the solder joint is directly transmitted to the thermistor, so that the temperature of the solder joint of the semiconductor device can be directly detected, and the detection accuracy can reach within ±0.5℃. Alternatively, for example, if the temperature at a certain position on the circuit board needs to be detected, the first conductive part 11 is placed at the to-be-detected position and used as a to-be-detected heat source, and the temperature of the first conductive part 11 is directly transmitted to the thermistor, so that the temperature at the target position can be directly detected.

[0103] In some embodiments, the temperature change rate of the thermistor is greater than or equal to 2Ω / ℃. For example, the temperature change rate of the thermistor is 2Ω / ℃, 3Ω / ℃, 5Ω / ℃, 7Ω / ℃, 10Ω / ℃, 13Ω / ℃, 15Ω / ℃, 17Ω / ℃ or 20Ω / ℃, etc.

[0104] For example, the resistance change range of the thermistor is one order of magnitude at 0℃-150℃.

[0105] The temperature change rate of the thermistor is limited to be greater than or equal to 2Ω / ℃, the feedback voltage output by the Wheatstone bridge 50 is easy to collect, the accuracy requirement of the collection equipment can be reduced, and the cost can be reduced. Of course, the temperature change rate of the thermistor can also be less than 2Ω / ℃.

[0106] In some embodiments, the center resistance value of the thermistor in the Wheatstone bridge 50 is 200Ω-3000Ω. For example, the center resistance value of the thermistor is 200Ω, 300Ω, 500Ω, 700Ω, 1000Ω, 1300Ω, 1500Ω, 1700Ω, 2000Ω, 2300Ω, 2500Ω, 2700Ω or 3000Ω, etc.

[0107] In some embodiments, the non-thermistor resistor in Wheatstone bridge 50 has a center resistance value of 200Ω-3000Ω. For example, the non-thermistor resistor has a center resistance value of 200Ω, 300Ω, 500Ω, 700Ω, 1000Ω, 1300Ω, 1500Ω, 1700Ω, 2000Ω, 2300Ω, 2500Ω, 2700Ω, or 3000Ω, etc.

[0108] The voltage output by first output O1 and second output O2 of Wheatstone bridge 50 can be fed back to the resistance value change of the thermistor, and the output voltage is positively correlated with the center resistance value of the resistance. Therefore, when the center resistance value of the resistance is too small, the thermistor has a small temperature change value, the current change on the thermistor is not obvious, the output voltage is too small, and the temperature detection accuracy is affected. When the center resistance value of the resistance is too large, the area of the resistance needs to be increased, which occupies too many wiring resources, and is not conducive to the integration of Wheatstone bridge 50 in the PCB.

[0109] In some embodiments, the thermistor in Wheatstone bridge 50 has a square resistance of 200Ω-3000Ω. For example, the thermistor has a square resistance of 200Ω, 300Ω, 500Ω, 700Ω, 1000Ω, 1300Ω, 1500Ω, 1700Ω, 2000Ω, 2300Ω, 2500Ω, 2700Ω, or 3000Ω, etc.

[0110] In some embodiments, the non-thermistor resistor in Wheatstone bridge 50 has a square resistance of 200Ω-3000Ω. For example, the non-thermistor resistor has a square resistance of 200Ω, 300Ω, 500Ω, 700Ω, 1000Ω, 1300Ω, 1500Ω, 1700Ω, 2000Ω, 2300Ω, 2500Ω, 2700Ω, or 3000Ω, etc.

[0111] The square resistance is the square resistance, which refers to the resistance between the edges of a square thin-film conductive material. The product of the square resistance and L / W (L: length, W: width) is the center resistance value of the resistance.

[0112] When the square resistance of the resistance is too small, more wiring resources are needed to obtain the target thin-film resistance center value. When the center value of the thermistor is too small, the resistance value change caused by the temperature change of the thermistor is small, the current change on the thermistor is not obvious, and the temperature detection accuracy is affected. When the square resistance of the resistance is too large, it is not easy to achieve a high temperature coefficient of resistance (TCR), and the change in resistance value caused by temperature change accounts for a small proportion of the total resistance value, and the detectable change in voltage is smaller, which is not conducive to obtaining an accurate temperature change value.

[0113] For example, taking the solder joint temperature for testing the SOC as an example, the SOC is soldered to the first conductive part 11 through the solder joint. The line width and line spacing on the PCB are conventional 20 μm / 20 μm, the width of the resistors in the Wheatstone bridge 50 is also 20 μm, a resistor with a center resistance of 2000 Ω is designed, the square resistance is 200 Ω, and a resistor segment with a length of 200 um needs to be obtained.

[0114] Figure 4A and Figure 4B A topological schematic diagram of a Wheatstone bridge provided by an embodiment of the present application.

[0115] In some embodiments, as shown in Figure 4A The Wheatstone bridge 50 includes four resistors, which are a seventh resistor R7, an eighth resistor R8, a ninth resistor R9, and a tenth resistor R10.

[0116] One end of the seventh resistor R7 is coupled to the first input terminal I1, and the other end of the seventh resistor R7 is coupled to the first output terminal O1. One end of the eighth resistor R8 is coupled to the first input terminal I1, and the other end of the eighth resistor R8 is coupled to the second output terminal O2. One end of the ninth resistor R9 is coupled to the first output terminal O1, and the other end of the ninth resistor R9 is coupled to the second input terminal I2. One end of the tenth resistor R10 is coupled to the second output terminal O2, and the other end of the tenth resistor R10 is coupled to the second input terminal I2.

[0117] For example, the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10 include thermistors.

[0118] For example, one of the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10 is a thermistor. That is, the seventh resistor R7 can be a thermistor, and the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10 can be non-thermistor resistors. Alternatively, the eighth resistor R8 can be a thermistor, and the seventh resistor R7, the ninth resistor R9, and the tenth resistor R10 can be non-thermistor resistors. Alternatively, the ninth resistor R9 can be a thermistor, and the seventh resistor R7, the eighth resistor R8, and the tenth resistor R10 can be non-thermistor resistors. Alternatively, the tenth resistor R10 can be a thermistor, and the seventh resistor R7, the eighth resistor R8, and the ninth resistor R9 can be non-thermistor resistors.

[0119] Alternatively, for example, a plurality of the seventh resistor R7, the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10 are thermistors. That is, the seventh resistor R7 and the eighth resistor R8 can be thermistors, and the ninth resistor R9 and the tenth resistor R10 can be non-thermistor resistors. Alternatively, the ninth resistor R9 and the tenth resistor R10 can be thermistors, and the seventh resistor R7 and the eighth resistor R8 can be non-thermistor resistors, and so on.

[0120] In some embodiments, the central resistance of the seventh resistor R7 is equal to the central resistance of the eighth resistor R8, the central resistance of the ninth resistor R9 is equal to the central resistance of the tenth resistor R10, and the central resistance of the seventh resistor R7 is not equal to the central resistance of the ninth resistor R9.

[0121] exist Figure 4A In the Wheatstone bridge 50 shown, null or balanced conditions are used to find unknown resistances. The seventh resistor R7 is a thermistor. 10 =R9*R8, therefore, when there is no temperature change, R7*R 10 -R9*R8=0,U 12-13 / U 11 =(R7*R 10 -R9*R8) / [(R7+R9)*(R 10 +R8)], Wheatstone bridge 50 output U 12-13 = 0. When the temperature changes, the resistance of the thermistor changes, R7′*R 10 -R9*R8≠0U 12-13 / U 11 =(R7′*R 10 -R9*R8) / [(R7′+R9)*(R 10 +R8)], Wheatstone bridge 50 output U 12-13 ≠0. When the resistance values ​​of the eighth resistor R8, the ninth resistor R9 and the tenth resistor R10 are fixed, 12-13 The change in the resistance value (R7′) of the thermistor R7 can be obtained. Furthermore, the temperature change can be obtained through the temperature change rate of the thermistor.

[0122] Wherein, R7 is the resistance value of the seventh resistor R7 when there is no temperature change, R7′ is the resistance value of the seventh resistor R7 when the temperature changes, R8 is the resistance value of the eighth resistor R8, R9 is the resistance value of the ninth resistor R9, R 10 is the resistance of the tenth resistor R10, U 11 is the voltage at the first conductive part 11, U 12-13 is the output voltage of the Wheatstone bridge 50.

[0123] In other embodiments, the central resistance of the seventh resistor R7, the central resistance of the eighth resistor R8, the central resistance of the ninth resistor R9, and the central resistance of the tenth resistor R10 are equal, which can simplify the design and manufacturing difficulty.

[0124] Regarding the structure of the Wheatstone bridge 50, in other embodiments, such as Figure 4BAs shown, the Wheatstone bridge 50 includes six resistors, which are a first resistor R1, a second resistor R2, a third resistor R3, a fourth resistor R4, a fifth resistor R5, and a sixth resistor R6.

[0125] One end of the first resistor R1 is coupled to the first input terminal I1, and the other end of the first resistor R1 is coupled to the first output terminal O1. One end of the second resistor R2 is coupled to the first input terminal I1, and the other end of the second resistor R2 is coupled to the second output terminal O2. One end of the third resistor R3 is coupled to the first output terminal O1, and the other end of the third resistor R3 is coupled to the second output terminal O2. One end of the fourth resistor R4 is coupled to the first output terminal O1, and the other end of the fourth resistor R4 is coupled to one end of the fifth resistor R5. The other end of the fifth resistor R5 is coupled to one end of the sixth resistor R6, and the other end of the sixth resistor R6 is coupled to the second output terminal O2.

[0126] For example, in the Wheatstone bridge 50 shown, Figure 4B In the Wheatstone bridge 50 shown, the fourth resistor R4 and the sixth resistor R6 are thermistors, and the other resistors are non-thermistor resistors. The fourth resistor R4 and the sixth resistor R6 are coupled to the reference ground terminal to form a return loop.

[0127] Due to the requirement of low power consumption, the center value of the thermistor in the Wheatstone bridge 50 needs to be large. However, due to various factors, the center value of a thermistor cannot be made very large, but by Figure 4B In the topology design in the Wheatstone bridge 50, two thermistors are arranged, which can be equivalent to a thermistor with a large center value in the Wheatstone bridge 50. Moreover, the two thermistors detect the temperatures at two positions, which is better than arranging two Figure 4A In the Wheatstone bridge 50 shown, Figure 4B The Wheatstone bridge shown has fewer resistors and occupies less area. By arranging the fifth resistor R5, the voltage drop in the Wheatstone bridge 50 can be avoided from being too low. By arranging the third resistor R3, the temperature change rate of the fourth resistor R4 and the sixth resistor R6 can be amplified, thereby improving the detection accuracy.

[0128] In some embodiments, the Wheatstone bridge 50 can also not include the fifth resistor R5, and the fourth resistor R4 and the sixth resistor R6 are directly coupled in series.

[0129] In some embodiments, the Wheatstone bridge 50 can also not include the third resistor R3, and the third resistor R3 is not coupled between the first output terminal O1 and the second output terminal O2.

[0130] Of course, the above is only an exemplary enumeration of the structure of the Wheatstone bridge 50 provided by the embodiments of the present application, and does not constitute a limitation on the embodiments of the present application.

[0131] Figure 5A A schematic diagram of a structure of a PCB is provided for an embodiment of the present application.

[0132] In some embodiments, as shown in FIG. 1, the Wheatstone bridge 50 includes a plurality of resistors, and the thermistor is located in the first conductor layer 10. Figure 5A Figure 5A In some embodiments, as shown in FIG. 1, the Wheatstone bridge 50 includes a plurality of resistors, and the thermistor is located in the first conductor layer 10. Figure 4A

[0133] The thermistor is located in the first conductor layer 10, and the first conductive part 11 is also located in the first conductor layer 10. The distance between the thermistor and the first conductive part 11 can be shortened, so that the thermistor can accurately feedback the temperature of the first conductive part 11, thereby improving the detection accuracy.

[0134] For example, the distance between the end of the thermistor (the seventh resistor R7) close to the first conductive part 11 and the end of the first conductive part 11 close to the thermistor is 5 μm, 10 μm, 50 μm, 100 μm, 200 μm, 300 μm, 400 μm, 500 μm, 600 μm, 700 μm, 800 μm, 900 μm, 1 mm, etc.

[0135] In some technologies, a thermistor is attached to a device to be detected on a circuit board, and the temperature of the device to be detected is detected through the thermistor. Because of the characteristics of the thermistor itself, the thermistor needs to be at least 3 mm to 5 mm away from the device to be detected to accurately measure the temperature. The thin film resistor used in the present application can read the instantaneous temperature change and will not cause deviation in the result due to the drastic change in temperature. Therefore, the distance between the thermistor and the first conductive part 11 can be 5 μm to 1 mm, so that the scheme of the present application can improve the detection accuracy and also achieve the purpose of product miniaturization.

[0136] In some embodiments, as shown in FIG. 1, the Wheatstone bridge 50 includes a plurality of resistors, and the thermistor is located in the first conductor layer 10. Figure 5B

[0137] Of course, the thermistor can be located in any one of the second conductor layers 30. The thermistor can be arranged in the same layer as the non-thermistor, or the thermistor can be arranged in a different layer from the non-thermistor. The present embodiment does not limit the arrangement position of the thermistor and the non-thermistor in the Wheatstone bridge 50, and the arrangement mode described herein is only an example.

[0138] In some embodiments, as shown in FIG. 1, the Wheatstone bridge 50 includes a plurality of resistors, and the thermistor is located in the first conductor layer 10. Figure 5A In some embodiments, as shown in FIG. 1, the Wheatstone bridge 50 includes a plurality of resistors, and the thermistor is located in the first conductor layer 10.​​​

[0139] The plurality of non-thermistors may be located in the same second conductor layer 30 , or in different second conductor layers 30 . In this case, the PCB includes multiple second conductor layers 30 .

[0140] Since the material of the thermistor is different from that of the non-thermistor, the process difficulty can be reduced by arranging the non-thermistor and the thermistor in layers.

[0141] Figure 5C and Figure 5D A disassembly diagram of a PCB provided in an embodiment of the present application.

[0142] by Figure 4A As an example of the Wheatstone bridge shown in FIG. 1 , the layout of the seventh resistor R7, the first conductive portion 11, the second conductive portion 12, and the third conductive portion 13 in the first conductor layer 10 can be as follows: Figure 5C In some embodiments, the second input terminal I2 is further coupled to the reference ground terminal GND to form a return loop. The layout of the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10 on the second conductor layer 30 can be as follows: Figure 5D As shown. The first via in the first conductor layer 10 and the first via in the second conductor layer 30 are connected via a first via, the second via in the first conductor layer 10 and the second via in the second conductor layer 30 are connected via a second via, the third via in the first conductor layer 10 and the third via in the second conductor layer 30 are connected via a third via, and the fourth via in the first conductor layer 10 and the fourth via in the second conductor layer 30 are connected via a fourth via. The first, second, third, and fourth vias extend through the second dielectric layer 40 between the first conductor layer 10 and the second conductor layer 30.

[0143] The embodiment of the present application does not limit the placement of multiple resistors in the Wheatstone bridge 50. Figure 4A and Figure 4B The connection relationship shown is sufficient.

[0144] Figure 6A A topological diagram of a detection circuit in a circuit board provided in an embodiment of the present application is shown. Figure 6B A schematic diagram of the structure of a PCB provided in an embodiment of the present application.

[0145] In some embodiments, as Figure 6A As shown, the PCB further includes an eleventh resistor R11, which is coupled to the first input terminal I1 of the Wheatstone bridge 50. For example, the PCB further includes a fourth conductive portion 14, and the eleventh resistor R11 is coupled between the fourth conductive portion 14 and the first input terminal I1.

[0146] For example, Figure 6BAs shown, the eleventh resistor R11 is a thin film resistor. For example, the eleventh resistor R11 can be disposed in the same layer as the non-thermally sensitive resistor in the Wheatstone bridge 50. Of course, the eleventh resistor R11 can also be disposed in the same layer as the non-thermally sensitive resistor in the Wheatstone bridge 50, Figure 6B It is only a schematic.

[0147] By setting the eleventh resistor R11 in series with the Wheatstone bridge 50, it is equivalent to setting a pull-up resistor, and the series resistance value of the eleventh resistor R11 and the Wheatstone bridge 50 can be increased to reduce the power consumption of the detection circuit.

[0148] Next, the structure of the first conductor layer 10 and the second conductor layer 30 in the PCB will be described schematically in conjunction with the PCB preparation method provided by the embodiments of the present application.

[0149] Figure 7 A flowchart of a PCB preparation method provided by the embodiments of the present application is shown in Figures 8A-10 A schematic diagram of a PCB preparation process provided by the embodiments of the present application is shown in

[0150] The embodiments of the present application also provide a PCB preparation method, as shown in Figure 7 The PCB preparation method comprises the following steps.

[0151] S10, as shown in Figures 8A-8D At least one second conductor layer 30 and at least one second dielectric layer 40 are formed. The at least one second conductor layer 30 and the at least one second dielectric layer 40 are arranged alternately.

[0152] For example, step S10 comprises:

[0153] S11, forming a second dielectric layer 40. The embodiments of the present application do not limit the way of forming the second dielectric layer 40. For example, the second dielectric layer 40 can be formed by a vapor deposition process.

[0154] S12, forming a second conductor layer 30.

[0155] According to the structure of the PCB, steps S11 and S12 can be executed one or more times cyclically.

[0156] For example, when steps S11 and S12 are executed cyclically for multiple times, step S12 comprises the following at least once:

[0157] S121, as shown in Figure 8A A second resistor film 31' and a second conductive film 32' are formed on the surface of the second dielectric layer 40 in sequence.

[0158] For example, the second resistance film 31' can be formed by a sputtering process. The material of the second resistance film 31' includes, for example, a mixed metal to form a firm resistance film on the surface of the second dielectric layer 40. The material of the second resistance film 31' includes, for example, a nickel-chromium mixed metal or the like. The second conductor film 32' can be formed by a vapor deposition process. The material of the second conductor film 32' includes, for example, copper (Cu) or the like.

[0159] S122, as shown in Figure 8B The second resistance film 31' and the second conductor film 32' are patterned to form the second conductor film pattern 32" and the second resistance layer 31.

[0160] For example, the second resistance film 31' and the second conductor film 32' can be patterned by a wet etching process.

[0161] For example, a photoresist is formed on the surface of the second conductor film 32'. The photoresist covers the second conductor film 32'. The second resistance film 31' and the second conductor film 32' are patterned by an exposure, development, and acid etching process. The photoresist is retained at a position where the circuit is required to be retained, and removed at a position where the circuit is not required to be retained. The second resistance film 31' and the second conductor film 32' to be etched are developed. The second resistance film 31' and the second conductor film 32' not covered by the photoresist are removed by an acid etching solution, and the second resistance film 31' and the second conductor film 32' covered by the photoresist are retained. The photoresist is removed by an organic or alkaline stripping solution, and the retained second resistance film 31' and the second conductor film 32' are exposed. The retained second resistance film 31' serves as the second resistance layer 31 in the second conductor layer 30, and the retained second conductor film 32' serves as the second conductor film pattern 32". The second conductor film pattern 32" requires further processing.

[0162] S123, as shown in Figure 8C The second conductor film pattern 32" is patterned to expose part of the second resistance layer 31, and form the second conductor layer 32.

[0163] For example, the second conductor film pattern 32" can be patterned by a wet etching process to form the second conductor layer 32. The second conductor layer 32 includes a second opening. The second opening exposes the second resistance layer 31. The part of the second resistance layer 31 corresponding to the second opening (exposed) serves as a non-thermistor, and the part of the second resistance layer 31 covered by the second conductor layer 32 does not serve as a resistance in the Wheatstone bridge 50.

[0164] For example, a dry film is formed on the surface of the second conductive film pattern 32", and the dry film covers the second conductive film pattern 32". The second conductive film pattern 32" is patterned by using an exposure, development, and alkaline etching process. The dry film at the positions where the resistors (e.g., the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10) are to be formed is removed, and the dry film at other positions is retained, and the second conductive film pattern 32" to be etched is developed. The portions of the second conductive film pattern 32" that are not covered by the dry film are removed by using an alkaline etching solution, and the portions covered by the dry film are left. The portions of the second conductive film pattern 32" that are left serve as the second conductive layer 32 in the second conductor layer 30. The second resistor layer 31 is not etched by the alkaline etching solution, and the portions of the second resistor layer 31 covered by the second conductive layer 32 serve as conductive lines, and the portions of the second resistor layer 31 exposed by the second conductive layer 32 serve as resistors in the Wheatstone bridge 50. The alkaline etching solution can be, for example, a combination of copper chloride (CuCl2), hydrochloric acid (HCI), hydrogen peroxide (H2O2), and water (H2O).

[0165] The PCB provided by the embodiments of the present application is shown in FIG. 1. The PCB includes a first conductor layer 10, a second conductor layer 30, and a first dielectric layer 40. The first conductor layer 10 includes a first conductive layer 101 and a first resistor layer 102. The first conductive layer 101 includes a first conductive line 1011 and a first resistor 1012. The first resistor layer 102 is located below the first conductive line 1011. The first resistor layer 102 includes a first thermistor 1021 and a first non-thermistor resistor 1022. The first thermistor 1021 is located below the first conductive line 1011, and the first non-thermistor resistor 1022 is located above the first conductive line 1011. Figure 8C The structure of at least one second conductor layer 30 includes a second conductive layer 32 and a second resistor layer 31. The second resistor layer 31 includes a non-thermistor resistor (e.g., the eighth resistor R8, the ninth resistor R9, and the tenth resistor R10). The materials of the thermistor and the non-thermistor resistor are different, and therefore, the thermistor and the non-thermistor resistor are layered, which simplifies the manufacturing process.

[0166] In some embodiments, the second conductive layer 32 is located on the surface of the second resistor layer 31 facing away from the second dielectric layer 40 (the surface facing the first conductor layer 10). The second conductive layer 32 has a second opening, and the portions of the second resistor layer 31 corresponding to the second opening serve as non-thermistor resistors. The portions of the second conductive layer 32 and the first resistor layer 101 are layered, and the portions serve as conductive lines of the second conductor layer 30. In this way, in the process of manufacturing the second conductor layer 30, the second conductive layer 32 and the second resistor layer 31 can be processed synchronously in some processes, which simplifies the manufacturing process.

[0167] In some embodiments, the resistivity of the material of the second conductive layer 32 is less than the resistivity of the material of the second resistor layer 31. Then, the conductivity of the material of the first conductive layer 102 is greater than the resistivity of the material of the first resistor layer 101. Therefore, the first resistor layer 101 is located below the first conductive layer 102, and does not affect the transmission of signals in the first conductive layer 102.

[0168] In some embodiments, the second resistance layer 31 has a thickness of 10 nm to 1000 nm. For example, the second resistance layer 31 has a thickness of 10 nm, 30 nm, 50 nm, 70 nm, 100 nm, 130 nm, 150 nm, 170 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, etc.

[0169] Due to the limited space in the PCB, the thickness of the second resistance layer 31 is too thin, and the resistance made in the limited space cannot meet the detection requirements. If the thickness of the second resistance layer 31 is too thick, it will affect the punching quality, the thickness of the circuit board, etc.

[0170] Alternatively, for example, when steps S11 and S12 are repeatedly performed multiple times, step S12 at least once includes:

[0171] S121, forming a second conductive film 32' on the surface of the second dielectric layer 40.

[0172] S122, patterning the second conductive film 32' to form a second conductive layer (with a wiring pattern). That is, the second conductive layer 30 only includes the second conductive layer 32 and no longer includes the second resistance layer 31.

[0173] The PCB provided by the embodiments of the present application, as shown in Figure 8C may have at least one second conductive layer 30 structure that only includes the second conductive layer 32 and does not include the second resistance layer 31, that is, the second conductive layer 30 does not integrate the resistance in the Wheatstone bridge 50.

[0174] S13, as shown in Figure 8D , forming a second dielectric layer 40, the second dielectric layer 40 covering the second conductive layer 30.

[0175] S20, as shown in Figures 9A-9C , forming a first conductive layer 10, the first conductive layer 10 being located on the side of the second dielectric layer 40 away from the second conductive layer 30; the first conductive layer 10 including a first conductive part 11, a second conductive part 12, and a third conductive part 13.

[0176] For example, step S20 includes:

[0177] S21, as shown in Figure 9A , sequentially forming a first resistance film 101' and a first conductive film 102' on the surface of the second dielectric layer 40 away from the second conductive layer 30 formed in the last step of step S10.

[0178] For example, a temperature-sensitive semiconductor compound is incorporated into the material used in a conventional thin-film resistor to obtain a temperature-sensitive thin-film resistor film layer.

[0179] S22, as shown, the first resistance film 101'and the first wire film 102'are patterned to form the first wire film pattern 102 " and the first resistance layer 101. Figure 9B

[0180] For example, a wet etching process is used to pattern the first wire film 102'and the first resistance film 101'to form the first wire layer 102, which includes a first opening that exposes the first resistance layer 101. The part of the first resistance layer 101 corresponding to (exposed by) the first opening serves as a thermistor, and the part of the first resistance layer 101 covered by the first wire layer 102 is not used as a resistor in the Wheatstone bridge 50.

[0181] For example, an exposure, development, and acid etching process is used to pattern the first wire film 102'and the first resistance film 101 '.

[0182] First, a dry film is formed on the surface of the first wire film 102 ', covering the first wire film 102 '. An exposure, development, and acid etching process is used to pattern the first wire film 102'and the first resistance film 101 '. Then, the dry film at the positions where the circuit needs to be retained is retained, and the dry film at the positions where it is not needed is removed, and the first wire film 102'and the first resistance film 101'to be etched are developed. Then, the parts of the first wire film 102'and the first resistance film 101'that are not covered by the dry film are removed using an acid etching solution, leaving the parts covered by the dry film. The remaining part of the first resistance film 101'serves as the first resistance layer 101 in the first conductor layer 10, and the remaining part of the first wire film 102'serves as the first wire film pattern 102 ", which needs to be further processed.

[0183] S23, as shown, the first wire film pattern 102 " is patterned to expose part of the first resistance layer 101 to form the first wire layer 102. Figure 9C

[0184] For example, a wet etching process is used to pattern the first wire film pattern 102 ".

[0185] For example, an exposure, development, and alkaline etching process is used to pattern the first wire film pattern 102 ".

[0186] ​​For example, after step S22 is performed, the dry film covering the surface of the first conductive film pattern 102" is removed, and a dry film covering the first conductive film pattern 102" and the second dielectric layer 40 is reformed. The dry film at the position where the resistor (e.g., the seventh resistor R7) is to be formed is removed, and the dry film at other positions is retained, and the first conductive film pattern 102" to be etched is developed. Then, the portions of the first conductive film pattern 102" not covered by the dry film are removed using an alkaline etching solution, leaving the portions covered by the dry film. The remaining portions of the first conductive film pattern 102" serve as the first conductive layer 102 in the first conductor layer 10. The first resistor layer 101 is not etched by the alkaline etching solution, and the portions of the first resistor layer 101 covered by the first conductive layer 102 serve as conductive lines, and the portions of the first resistor layer 101 exposed by the first conductive layer 102 serve as resistors in the Wheatstone bridge 50. Finally, the dry film is removed using an organic or alkaline stripping solution, exposing the remaining first conductive layer 102 and the first resistor layer 101.

[0187] In some embodiments, the thickness of the first resistor layer 101 is 10 nm to 1000 nm. For example, the thickness of the first resistor layer 101 is 10 nm, 30 nm, 50 nm, 70 nm, 100 nm, 130 nm, 150 nm, 170 nm, 200 nm, 250 nm, 300 nm, 350 nm, 400 nm, 450 nm, 500 nm, 550 nm, 600 nm, 650 nm, 700 nm, 750 nm, 800 nm, 850 nm, 900 nm, 950 nm, 1000 nm, etc.

[0188] Because of the limited space in the PCB, if the thickness of the first resistor layer 101 is too thin, the resistors formed in the limited space cannot meet the detection requirements. If the thickness of the first resistor layer 101 is too thick, it will affect the punching quality, the thickness of the circuit board, etc.

[0189] The PCB provided by the embodiments of the present application includes the first conductive layer 10 including the first conductive layer 102 and the first resistor layer 101, and the first resistor layer 101 includes a thermistor. By placing the thermistor in the Wheatstone bridge 50 and the first conductive part 11 in the PCB in the same layer, the thermistor can be placed close to the first conductive part 11, so as to improve the accuracy of the temperature feedback of the thermistor.

[0190] In some embodiments, first conductive layer 102 is disposed on the surface of first resistive layer 101 facing away from second dielectric layer 40 (facing first dielectric layer 20). First conductive layer 102 has a first opening, and the portion of first resistive layer 101 corresponding to the first opening functions as a thermistor. The portion of first resistive layer 101 exposed by first conductive layer 102 functions as a resistor, while the portion of second conductive layer 32 overlapping first resistive layer 101 functions as the conductive wire of second conductive layer 30. Thus, during the fabrication of first conductive layer 10, first conductive layer 102 and first resistive layer 101 can be processed simultaneously in some processes, simplifying the fabrication process.

[0191] In some embodiments, the resistivity of the material of first conductive layer 102 is lower than the resistivity of the material of first resistive layer 101. Therefore, the conductivity of the material of first conductive layer 102 is higher than the resistivity of the material of first resistive layer 101. Therefore, even if first resistive layer 101 is located below first conductive layer 102, it will not affect signal transmission in first conductive layer 102.

[0192] When the circuit board further includes an eleventh resistor R11, the manufacturing process of the eleventh resistor R11 can be the same as the manufacturing process of the thermosensitive electron in the Wheatstone bridge 50. The only difference is that the eleventh resistor R11 is made of a non-thermistor film.

[0193] S30, such as Figure 10 As shown, a first dielectric layer 20 is formed, and the first dielectric layer 20 covers the first conductor layer 10 , exposing the first conductive portion 11 , the second conductive portion 12 and the third conductive portion 13 .

[0194] A Wheatstone bridge 50 is integrated in the first conductor layer 10 and the second conductor layer 30. The structure of the resistors in the Wheatstone bridge 50 is designed by designing the shape of the first resistor layer 101 exposed by the first wire layer 102 and the shape of the second resistor layer 31 exposed by the second wire layer 32. The connection between the resistors and the connection between the resistors and the first conductive portion 11, the second conductive portion 12, and the third conductive portion 13 are achieved through the patterns of the first wire layer 102 and the second wire layer 32.

[0195] In some embodiments, at least one of the multiple resistors included in the Wheatstone bridge 50 is a thin film resistor, which can reduce the occupied area of ​​the Wheatstone bridge 50 .

[0196] Figure 11 A schematic structural diagram of a circuit board assembly provided in an embodiment of the present application.

[0197] The present application also provides a circuit board assembly, which can be provided on the middle frame of the electronic device provided in the present application. Figure 11As shown, the circuit board assembly includes a processing unit and a PCB. The PCB includes any of the above-described PCBs, and the processing unit is coupled to the second conductive part 12 and the third conductive part 13 in the PCB, respectively.

[0198] The voltage measured by the Wheatstone bridge 50 for temperature feedback is transmitted to the processing unit, which processes the voltage to obtain the temperature at the position of the first conductive part 11. The processing unit, for example, includes a microcontroller unit (MCU), and the MCU has a spare channel on the circuit board to detect the voltage change of the Wheatstone bridge 50, thereby obtaining the resistance change and finally obtaining the temperature change.

[0199] The circuit board assembly further includes a heat source to be measured, which can be connected to the first conductive part 11 or directly use the first conductive part 11 as the heat source to be measured. In this way, the Wheatstone bridge 50 is directly connected to the heat source to be measured, and the temperature change can be quickly and accurately measured.

[0200] Figure 12 A structural schematic diagram of a circuit board assembly provided by an embodiment of the present application.

[0201] In some embodiments, for example, the first dielectric layer 20 exposes the first conductive part 11, and the heat source to be measured can be connected to the first conductive part 11, and the Wheatstone bridge 50 measures the temperature change of the heat source to be measured through the first conductive part 11.

[0202] For example, as Figure 12 shown, the circuit board assembly further includes a semiconductor device connected to the first conductive part 11. The solder joint of the semiconductor device is directly connected to the first conductive part 11 as the heat source to be measured. The semiconductor device, for example, includes a chip such as a SOC, an RFIC, a PMU, a power device, or a battery protection board, etc.

[0203] In some embodiments, the circuit board assembly further includes a back-end circuit coupled to the Wheatstone bridge 50 of the circuit board.

[0204] The back-end circuit, for example, can be a reference ground voltage terminal or other semiconductor devices. It is equivalent to that the Wheatstone bridge 50 is coupled between the semiconductor device and the normal back-end circuit, so that the temperature at the solder joint corresponding to the first conductive part 11 can be measured. Alternatively, it is understood that the Wheatstone bridge 50 is coupled in series with the back-end circuit.

[0205] Figure 13 A structural schematic diagram of a circuit board assembly provided by an embodiment of the present application.

[0206] In some embodiments, as Figure 13 shown, the circuit board assembly further includes a back-end circuit coupled to the first conductive part 11.

[0207] The semiconductor device and the normal back-end circuit are both coupled with the first conductive part 11, that is, the temperature at the corresponding solder point of the first conductive part 11 can be measured. Alternatively, it is understood that the Wheatstone bridge 50 is coupled in parallel with the back-end circuit, which can reduce the power loss of the Wheatstone bridge 50 to the back-end circuit.

[0208] Figure 14 A structural schematic diagram of a circuit board assembly provided by an embodiment of the present application.

[0209] In some embodiments, the first conductive part 11 is a heat source to be measured, and the Wheatstone bridge 50 measures the temperature change of the first conductive part 11. At this time, the first conductive part 11 may, for example, be a section of signal line, a solder pad, etc.

[0210] For example, as shown in Figure 14 The first medium layer 20 exposes the first conductive part 11, and the circuit board assembly further includes an excitation source coupled with the first conductive part 11. The excitation source may, for example, be an input power source on the circuit board, etc., and the excitation source is used to provide a signal source for the Wheatstone bridge 50. The circuit board assembly further includes a back-end circuit and a semiconductor device, and the semiconductor device and the back-end circuit are both not coupled with the first conductive part 11.

[0211] In this way, it is equivalent to integrating the Wheatstone bridge 50 as a temperature detection circuit on the circuit board. By placing the Wheatstone bridge 50 at the position to be measured, the temperature at the position to be measured can be obtained.

[0212] For example, the Wheatstone bridge 50 is arranged beside the chip or the heat generating device to be measured, at this time, the Wheatstone bridge 50 is not directly electrically connected with the solder pad to be measured, and the temperature is conducted to the thermistor through the medium to realize temperature monitoring. Since the Wheatstone bridge 50 itself has a certain resistance, there will be a series voltage division effect. Therefore, the Wheatstone bridge 50 is not electrically connected with the solder pad to be measured, and will not consume the power consumption of the back-end circuit normally coupled with the solder pad to be measured.

[0213] Alternatively, for example, a temperature sensitive device is arranged on the circuit board, and the temperature sensitive device will be damaged when the temperature is too high. The Wheatstone bridge 50 is arranged near the temperature sensitive device, which can detect the temperature at this position in time and make adaptive adjustment to ensure that the temperature sensitive device is not damaged.

[0214] Alternatively, for example, the first medium layer 20 does not expose the first conductive part 11, and the first conductive part 11 is a section of signal line, and the temperature of the signal line is directly measured.

[0215] Figure 15 A layout diagram of a first conductor layer provided by an embodiment of the present application.

[0216] For example, as shown inFigure 15 As shown, the first conductor layer 10 further comprises a semiconductor device pad for coupling with a semiconductor device. The semiconductor device pad serves as a to-be-tested pad, and the first conductive part 11 is placed beside the semiconductor device pad.

[0217] Figure 16A And Figure 16B A structural schematic diagram of a circuit board assembly provided by an embodiment of the present application is shown in FIG. 1.

[0218] An embodiment of the present application further provides a circuit board assembly, as shown in Figure 16A As shown, the circuit board assembly comprises a processing unit, a circuit board, and a to-be-tested heat source.

[0219] The circuit board comprises a first conductive part 11 and a second conductive part 12, and a first dielectric layer 20, a first conductor layer 10, and a second dielectric layer 40 which are sequentially stacked.

[0220] The first conductor layer 10 comprises a thermistor NTC, which is coupled between the first conductive part 11 and the second conductive part 12, and the thermistor NTC is a thin-film resistor.

[0221] The processing unit is coupled with the second conductive part 12, as shown in Figure 16A As shown, the first dielectric layer 20 exposes the first conductive part 11, and the to-be-tested heat source is coupled with the first conductive part 11. Alternatively, as shown in Figure 16B The first conductive part 11 serves as the to-be-tested heat source, and the first dielectric layer 20 can not expose the first conductive part 11.

[0222] The circuit board assembly provided by the embodiment of the present application integrates the thermistor NTC inside the circuit board, detects the temperature change at the position of the thermistor NTC through the change of the resistance value of the thermistor NTC with temperature, and does not need an additional processing unit. The thermistor NTC can be flexibly arranged to detect the temperature of various to-be-tested positions in real time. Moreover, the first conductive part 11 is used as the to-be-tested heat source directly or the first conductive part 11 is used to connect with the to-be-tested heat source, and the thermistor NTC is directly coupled with the first conductive part 11. Therefore, the temperature change on the first conductive part 11 can be directly transmitted to the thermistor NTC, which is equivalent to that the thermistor NTC can directly sense the temperature change of the to-be-tested heat source, thereby realizing close-range, rapid, and direct detection of the temperature of the to-be-tested heat source.

[0223] Figure 17A A topological schematic diagram of a detection circuit provided by an embodiment of the present application is shown in FIG. 2. Figure 17B A structural schematic diagram of a circuit board assembly provided by an embodiment of the present application is shown in FIG. 1.

[0224] In some embodiments, as shown in Figure 17AAs shown, the PCB further comprises a first resistor R1. The first resistor R1 is coupled with the processing unit and the same one of the first conductive part 11 and the second conductive part 12. Then, the first resistor R1 is coupled with the second conductive part 12 to realize the series connection of the first resistor R1 and the thermistor NTC. For example, the PCB further comprises a third conductive part 13, and the first resistor R1 is coupled between the third conductive part 13 and the second conductive part 12. The processing unit may, for example, be an MCU.

[0225] As shown in the example, Figure 17B As shown, the PCB comprises a plurality of second dielectric layers 40 and a second conductor layer 30, the second conductor layer 30 is arranged between adjacent second dielectric layers 40 (the side of the second dielectric layer 40 away from the first conductor layer 10), and the second conductor layer 30 comprises the first resistor R1. The second conductor layer 30 can be arranged close to the processing unit relative to the first conductor layer 10, or the second conductor layer 30 can be arranged away from the processing unit relative to the first conductor layer 10, and the embodiment of the present application is only a schematic.

[0226] By arranging the first resistor R1 in series with the thermistor NTC, a pull-up resistor is equivalent, and the series resistance value of the first resistor R1 and the thermistor NTC can be increased to reduce the power consumption of the detection circuit.

[0227] Figure 18A A topological schematic diagram of a detection circuit provided by an embodiment of the present application is shown in Figure 18B A structural schematic diagram of a circuit board assembly provided by an embodiment of the present application is shown in

[0228] In some embodiments, as shown in the example, Figure 18A As shown, the circuit board assembly further comprises a capacitor C, and the capacitor C is coupled in parallel with the thermistor NTC. The embodiment of the present application does not limit the integration manner of the capacitor C in the PCB. The capacitor C can be a chip capacitor, and the capacitor C can also be a film capacitor.

[0229] As shown in the example, Figure 18B The embodiment of the present application does not limit the integration manner of the capacitor C in the PCB, and the parallel connection of the capacitor C and the thermistor NTC can be realized.

[0230] By arranging the capacitor C in parallel with the thermistor NTC, a filter can be formed to improve the temperature-sensitive detection accuracy.

[0231] Figure 19A And Figure 19B A structural schematic diagram of a circuit board assembly provided by an embodiment of the present application is shown in

[0232] The embodiment further provides a circuit board assembly, as shown in the example, Figure 19A And Figure 19B The circuit board assembly comprises a processing unit, a circuit board, and a heat source to be detected.

[0233] The circuit board comprises a first conductive part 11' and a second conductive part 12', and a first dielectric layer 20, a first conductor layer 10 and a second dielectric layer 40 which are sequentially stacked. The processing unit is coupled to the first conductive part 11' and the second conductive part 12'. Figure 16A and Figure 16B The main difference is that the processing unit is coupled to the first conductive part 11' instead of the second conductive part 12'. The effect is the same as that of the circuit board assembly shown in Figure 16A and Figure 16B The effect is the same as that of the circuit board assembly shown in

[0234] Figure 20A A topological diagram of a detection circuit provided by an embodiment of the present application is shown in Figure 20B A structural diagram of a circuit board assembly provided by an embodiment of the present application is shown in

[0235] In some embodiments, as shown in Figure 20A the PCB further comprises a first resistor R1. The first resistor R1 and the processing unit are coupled to the same one of the first conductive part 11' and the second conductive part 12'. Then, the processing unit is coupled to the first conductive part 11', and the first resistor R1 is coupled to the first conductive part 11' to realize the series connection of the first resistor R1 and the thermistor NTC.

[0236] For example, as shown in Figure 20B the PCB comprises a plurality of second dielectric layers 40 and a plurality of second conductor layers 30, the second conductor layers 30 are arranged between adjacent second dielectric layers 40 (the side of the second dielectric layer 40 away from the first conductor layer 10), and the second conductor layers 30 comprise the first resistor R1, the first resistor R1 being coupled between the second conductive part 12' and a third conductive part 13'.

[0237] Figure 21A A topological diagram of a detection circuit provided by an embodiment of the present application is shown in Figure 21B A structural diagram of a circuit board assembly provided by an embodiment of the present application is shown in

[0238] In some embodiments, as shown in Figure 21A the circuit board assembly further comprises a capacitor C, the capacitor C being coupled in parallel with the thermistor NTC.

[0239] As shown in Figure 21B the present application does not limit the integration manner of the capacitor C in the PCB, and the capacitor C can be connected in parallel with the thermistor NTC.

[0240] The above merely provides the specific implementation of the present application, but the protection scope of the present application is not limited to this. Any change or replacement within the technical scope disclosed by the present application should be covered in the protection scope of the present application. Therefore, the protection scope of the present application should be subject to the protection scope of the claims.

Claims

1. A circuit board, characterized by, The application relates to a Wheatstone bridge, comprising a first conductor layer, a first dielectric layer, at least one second conductor layer and at least one second dielectric layer, and a Wheatstone bridge. The first conductor layer comprises a first conductive part, a second conductive part and a third conductive part. The first dielectric layer covers the first conductor layer and exposes the second conductive part and the third conductive part. The at least one second conductor layer and the at least one second dielectric layer are alternately arranged on a side of the first conductor layer away from the first dielectric layer. The Wheatstone bridge comprises a first input end, a second input end, a first output end, a second output end and a plurality of resistors. The resistors are located on the first conductor layer or the second conductor layer, the plurality of resistors comprises one or more thermistors, the first input end and the second input end are coupled to the first conductive part, the first output end is coupled to the second conductive part, and the second output end is coupled to the third conductive part.

2. The circuit board of claim 1, wherein The thermistor is located on the first conductor layer.

3. The circuit board according to claim 1 or 2, characterized by The plurality of resistors further comprises a plurality of non-thermistor resistors, and the non-thermistor resistors are located on the second conductor layer.

4. The circuit board according to any one of claims 1 to 3, characterized in that, At least one of the plurality of resistors is a thin-film resistor.

5. The circuit board according to any one of claims 1 to 4, characterized in that, The first conductor layer comprises a first wire layer and a first resistor layer, and the first resistor layer comprises the thermistor. The resistivity of the material of the first wire layer is smaller than the resistivity of the material of the first resistor layer.

6. The circuit board of claim 5, wherein, The first wire layer is arranged on a surface of the first resistor layer away from the second dielectric layer, the first wire layer has a first opening, and a part of the first resistor layer corresponding to the first opening serves as the thermistor.

7. The circuit board according to claim 5 or 6, characterized in that, The thickness of the first resistor layer is 10-1000 nm.

8. The circuit board according to any one of claims 3 to 7, characterized in that At least one of the second conductor layers comprises a second wire layer and a second resistor layer, and the second resistor layer comprises the non-thermistor resistor. The resistivity of the material of the second wire layer is smaller than the resistivity of the material of the second resistor layer.

9. The circuit board of claim 8, wherein, The second wire layer is arranged on a surface of the second resistor layer facing the first conductor layer, the second wire layer has a second opening, and a part of the second resistor layer corresponding to the second opening serves as the non-thermistor resistor.

10. The circuit board according to any one of claims 1 to 9, characterized in that, The plurality of resistors comprises a first resistor, a second resistor, a third resistor, a fourth resistor, a fifth resistor and a sixth resistor, the fourth resistor and the sixth resistor are the thermistors. One end of the first resistor is coupled to the first input end, and the other end of the first resistor is coupled to the first output end. One end of the second resistor is coupled to the first input end, and the other end of the second resistor is coupled to the second output end. One end of the third resistor is coupled to the first output end, and the other end of the third resistor is coupled to the second output end. One end of the fourth resistor is coupled to the first output end, and the other end of the fourth resistor is coupled to one end of the fifth resistor. The other end of the fifth resistor is coupled to one end of the sixth resistor, and the other end of the sixth resistor is coupled to the second output end.

11. The circuit board according to any one of claims 1 to 9, characterized in that, The plurality of resistors comprises a seventh resistor, an eighth resistor, a ninth resistor and a tenth resistor, one of the seventh resistor, the eighth resistor, the ninth resistor and the tenth resistor is the thermistor. One end of the seventh resistor is coupled with the first input end, and the other end of the seventh resistor is coupled with the first output end. One end of the eighth resistor is coupled with the first input end, and the other end of the eighth resistor is coupled with the second output end. One end of the ninth resistor is coupled with the first output end, and the other end of the ninth resistor is coupled with the second input end. One end of the tenth resistor is coupled with the second output end, and the other end of the tenth resistor is coupled with the second input end.

12. The circuit board of any of claims 1-11, wherein, The temperature change rate of the thermistor is greater than or equal to 2Ω / ℃.

13. The circuit board of any of claims 1-12, wherein, The sheet resistance of the thermistor is 200Ω-3000Ω, or the central resistance value of the thermistor is 200Ω-3000Ω.

14. The circuit board of any of claims 5-12, wherein, The distance from the thermistor to the first conductive part is 5μm-1mm.

15. The circuit board of any of claims 1-14, wherein, The circuit board further comprises an eleventh resistor, which is coupled with the first input end.

16. A circuit board assembly, characterized by The circuit board assembly further comprises a backend circuit, which is coupled with the first conductive part.

17. The circuit board assembly of claim 16, wherein, The circuit board assembly further comprises a backend circuit, which is coupled with the Wheatstone bridge of the circuit board.

18. The circuit board assembly of claim 16, wherein, The circuit board assembly further comprises an excitation source, which is coupled with the first conductive part.

19. The circuit board assembly of claim 16, wherein, The circuit board assembly further comprises a backend circuit, which is coupled with the first conductive part.

20. A circuit board assembly, characterized by The circuit board assembly further comprises an excitation source, which is coupled with the first conductive part. The circuit board assembly further comprises a backend circuit, which is coupled with the first conductive part. The circuit board assembly further comprises an excitation source, which is coupled with the first conductive part.

21. The circuit board assembly of claim 20, wherein, The circuit board assembly further comprises a backend circuit, which is coupled with the first conductive part.

22. The circuit board assembly of claim 21, wherein, The circuit board assembly further comprises an excitation source, which is coupled with the first conductive part.

23. An electronic device, comprising: The circuit board assembly further comprises a backend circuit, which is coupled with the first conductive part.

24. A method of manufacturing a circuit board, characterized by, The circuit board assembly further comprises an excitation source, which is coupled with the first conductive part. The circuit board assembly further comprises a backend circuit, which is coupled with the first conductive part. The circuit board assembly further comprises an excitation source, which is coupled with the first conductive part. The circuit board assembly further comprises a backend circuit, which is coupled with the first conductive part. The circuit board assembly further comprises an excitation source, which is coupled with the first conductive part. The circuit board assembly further comprises a backend circuit, which is coupled with the first conductive part. The circuit board assembly further comprises an excitation source, which is coupled with the first conductive part. The circuit board assembly further comprises a backend circuit, which is coupled with the first conductive part. 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The circuit board assembly further comprises a forming a first dielectric layer covering the first conductor layer, exposing the second conductive part and the third conductive part; The Wheatstone bridge includes a plurality of resistors, a first input terminal, a second input terminal, a first output terminal and a second output terminal, the resistors are located in the first conductor layer or the second conductor layer; the plurality of resistors includes one or more thermistors, the first input terminal and the second input terminal are coupled with the first conductive part, the first output terminal is coupled with the second conductive part, and the second output terminal is coupled with the third conductive part.

25. The method of manufacturing a circuit board according to claim 24, wherein The forming of the first conductor layer comprises: forming a first resistor film and a first conductor film on the surface of the second dielectric layer away from the second conductor layer in sequence; patterning the first conductor film and the first resistor film to form a first conductor film pattern and a first resistor layer; patterning the first conductor film pattern to expose part of the first resistor layer to form a first conductor layer.

26. The method of manufacturing a circuit board according to claim 24, wherein The patterning of the first conductor film and the first resistor film comprises: The first conductor film and the first resistor film are patterned by an exposure, development and acid etching process.

27. The method of manufacturing a circuit board according to claim 25 or 26, wherein, The patterning of the first conductor film pattern comprises: The first conductor film pattern is patterned by an exposure, development and alkaline etching process.

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