Flexible circuit assembly, method of parameter determination thereof, and earphone

Abstract

The application provides a flexible circuit assembly, a parameter determination method thereof and an earphone. The flexible circuit assembly comprises a flexible circuit board, a piezoelectric element, a counterweight part and a groove part. The flexible circuit board comprises a first functional section, an intermediate section and a second functional section distributed along the length direction thereof. The piezoelectric element is arranged in the first functional section. The counterweight part and the groove part are arranged in at least one of the intermediate section and the second functional section respectively or jointly. The counterweight part is used for cooperating with the groove part to weaken the structural resonance generated by the piezoelectric element exciting the flexible circuit board.

Description

Technical Field

[0001] This application relates to the field of electronic equipment technology, and more specifically, to a flexible circuit assembly, a method for determining the parameters thereof, and headphones. Background Technology

[0002] In related technologies, the flexible circuit board of in-ear headphones is usually equipped with surface-mount capacitors (such as audio SOC capacitors). These capacitors will generate periodic micro mechanical vibrations due to the piezoelectric effect under the action of audio electrical signals. The vibrations are transmitted to the flexible circuit board structure through the pads, causing the flexible circuit board to generate coupled resonance in a specific frequency band of 4kHz to 8kHz, resulting in a significant increase in noise (which can exceed 20 dBA) and causing performance degradation phenomena such as acoustic abnormalities and howling.

[0003] To address the aforementioned issues, existing technologies typically employ methods such as increasing the thickness of the flexible circuit board to improve overall rigidity, or applying adhesive to fix the surface-mount capacitors and the flexible circuit board area. However, increasing the thickness affects the bending performance and assembly space of the flexible circuit board; while adhesive fixing methods suffer from poor process consistency and insufficient long-term reliability.

[0004] Therefore, a new technical solution is needed to solve the above-mentioned technical problems. Summary of the Invention

[0005] The purpose of this application is to provide a flexible circuit component, a method for determining its parameters, and a new technical solution for headphones.

[0006] According to a first aspect of this application, a flexible circuit assembly is provided, comprising: a flexible circuit board including a first functional segment, an intermediate segment, and a second functional segment distributed along its length; a piezoelectric element disposed in the first functional segment; a counterweight and a recessed portion, wherein the counterweight and the recessed portion are respectively or jointly arranged in at least one segment of the intermediate segment and the second functional segment; the counterweight is used to cooperate with the recessed portion to reduce structural resonance generated by the piezoelectric element exciting the flexible circuit board.

[0007] Optionally, both the counterweight and the groove are located in the middle section.

[0008] Optionally, the first functional segment is formed as a fixed segment, the second functional segment is formed as a free segment, and the counterweight is located on the side of the groove near the first functional segment.

[0009] Optionally, the first functional segment is formed as a free segment, the second functional segment is formed as a fixed segment, and the groove portion is located on the side of the counterweight portion close to the first functional segment.

[0010] Optionally, both the first functional segment and the second functional segment are formed as fixed segments, and the groove portion is located on the side of the counterweight portion near the first functional segment.

[0011] Optionally, the intermediate section is provided with a plurality of grooves spaced apart along the length direction, and the grooves are elongated slots extending along the width direction of the flexible circuit board.

[0012] Optionally, the piezoelectric element is a chip capacitor; and / or, the counterweight is a counterweight block or a counterweight coating; and / or, the groove is a through groove or a blind groove.

[0013] Optionally, the flexible circuit board includes a first copper layer, a flexible base layer, and a second copper layer stacked together; the groove portion is formed as a blind groove penetrating the first copper layer or the second copper layer, or the groove portion is formed as a blind groove penetrating the first copper layer or the second copper layer and extending into the flexible base layer.

[0014] According to a second aspect of this application, a method for determining parameters of a flexible circuit assembly is provided, applied to the flexible circuit assembly described in any of the preceding claims, the method comprising: Obtain the initial vibration mode parameters of a flexible circuit board equipped with piezoelectric elements; A counterweight and a groove are provided in the middle section and / or the second functional section of the flexible circuit board; The current vibration mode parameters of the flexible circuit board are obtained again; The current vibration modal parameters are compared with the preset modal parameters; Adjust the design parameters of the groove and the counterweight based on the comparison results; The step of obtaining the current vibration mode parameters of the flexible circuit board is executed iteratively until the current vibration mode parameters of the flexible circuit board match the preset mode parameters. The design parameters of the groove and the counterweight corresponding to the matching of the preset modal parameters are used as the target design parameters.

[0015] According to a third aspect of this application, an earphone is provided, including the flexible circuit assembly described in any of the preceding claims.

[0016] According to the flexible circuit assembly of this application, the structural resonance generated by the piezoelectric element excitation of the flexible circuit board can be reduced through the synergistic effect of the counterweight and the groove. There is no need to thicken the circuit board or use glue for curing. It can effectively reduce working noise while maintaining the bending performance and assembly space of the flexible circuit board, and at the same time improve the consistency of product process and long-term reliability.

[0017] Other features and advantages of this application will become clear from the following detailed description of exemplary embodiments with reference to the accompanying drawings. Attached Figure Description

[0018] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments of the present application and, together with their description, serve to explain the principles of the present application.

[0019] Figure 1 This is a schematic diagram of the structure of a flexible circuit assembly according to an embodiment of this application; Figure 2 This is a schematic cross-sectional view of a flexible circuit board portion according to an embodiment of this application; Figure 3 This is a cross-sectional structural diagram of a flexible circuit board portion according to another embodiment provided in this application.

[0020] Figure Labels 10. Flexible circuit board; 101. First copper layer; 102. Flexible base layer; 103. Second copper layer; 11. First functional segment; 12. Middle segment; 121. Groove portion; 13. Second functional segment; 20. Piezoelectric element; 30. Counterweight portion. Detailed Implementation

[0021] Various exemplary embodiments of the present application will now be described in detail with reference to the accompanying drawings. It should be noted that, unless otherwise specifically stated, the relative arrangement, numerical expressions, and values ​​of the components and steps set forth in these embodiments do not limit the scope of the present application.

[0022] The following description of at least one exemplary embodiment is merely illustrative and is in no way intended to limit the scope of this application and its application or use.

[0023] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, such techniques, methods, and equipment should be considered part of the specification.

[0024] In all the examples shown and discussed herein, any specific values ​​should be interpreted as merely exemplary and not as limitations. Therefore, other examples of exemplary embodiments may have different values.

[0025] It should be noted that similar labels and letters in the following figures indicate similar items; therefore, once an item is defined in one figure, it does not need to be discussed further in subsequent figures.

[0026] The flexible circuit assembly according to embodiments of this application will now be described in detail with reference to the accompanying drawings.

[0027] like Figure 1 As shown, the flexible circuit assembly according to an embodiment of this application includes: a flexible circuit board 10, a piezoelectric element 20, a counterweight portion 30, and a recess portion 121.

[0028] Specifically, the flexible circuit board 10 includes a first functional segment 11, an intermediate segment 12, and a second functional segment 13 distributed along its length; the piezoelectric element 20 is disposed in the first functional segment 11; the counterweight 30 and the groove 121 are respectively or jointly arranged in at least one segment of the intermediate segment 12 and the second functional segment 13; the counterweight 30 is used to cooperate with the groove 121 to reduce the structural resonance generated by the piezoelectric element 20 exciting the flexible circuit board 10.

[0029] In some embodiments, the flexible circuit assembly of this application mainly includes a flexible circuit board 10 and a piezoelectric element 20. The flexible circuit board 10 is divided along its length into a first functional segment 11, an intermediate segment 12, and a second functional segment 13 connected in sequence. Multiple electronic components are mounted on the first functional segment 11, including the piezoelectric element 20. When the piezoelectric element 20 is working, it will generate periodic micro-vibrations. As a vibration excitation source, it can cause the flexible circuit board 10 to undergo coupled resonance, thereby leading to a significant increase in noise and causing performance degradation phenomena such as acoustic abnormalities and howling.

[0030] Based on this, in this embodiment of the application, a counterweight 30 and a groove 121 are provided on the flexible circuit board 10. The counterweight 30 and the groove 121 can be set on the intermediate section 12 and / or the second functional section 13 according to the actual situation. The counterweight 30 is configured to change the local mass distribution of the flexible circuit board 10, and the groove 121 is configured to adjust the local structural stiffness of the flexible circuit board 10. The counterweight 30 can change the local mass distribution of the circuit board, and the groove 121 can adjust the local structural stiffness of the circuit board. The counterweight 30 and the groove 121 are configured to cooperate to actively regulate the modal frequency and mode shape distribution of the flexible circuit board 10, break the original frequency band resonance conditions, and thereby reduce the structural resonance generated by the piezoelectric element 20 exciting the flexible circuit board 10.

[0031] Therefore, according to the flexible circuit assembly provided in this embodiment, the structural resonance generated by the piezoelectric element 20 exciting the flexible circuit board 10 can be reduced through the synergistic effect of the counterweight 30 and the groove 121. Without the need to thicken the circuit board or use glue for curing, the working noise can be effectively reduced while maintaining the bending performance and assembly space of the flexible circuit board 10, and the consistency of product process and long-term reliability can be improved.

[0032] In some specific embodiments of this application, both the counterweight 30 and the groove 121 are located in the middle section 12.

[0033] Specifically, the intermediate section 12 is the transition area between the functional sections at both ends of the flexible circuit board 10, and it is closer to the first functional section 11, where the piezoelectric element 20 is located, than the second functional section 13. Because the intermediate section 12 is closer to the piezoelectric element 20, the vibration energy generated by the piezoelectric element 20 has not yet fully diffused along the flexible circuit board 10 when it reaches the intermediate section 12, resulting in a more concentrated vibration response at the intermediate section 12. By concentrating the counterweight 30 and the groove 121 in the intermediate section 12, the local mass and stiffness distribution can be directly adjusted in the area of ​​concentrated vibration energy, allowing the adjustment effect to coincide with the area of ​​concentrated vibration energy. This achieves effective shift of the modal frequency with minimal structural modification, reduces structural resonance, lowers operating noise, saves assembly space, and adapts to the miniaturization design requirements of headphones.

[0034] According to one embodiment of this application, the first functional segment 11 is formed as a fixed segment, the second functional segment 13 is formed as a free segment, and the counterweight 30 is located on the side of the groove 121 close to the first functional segment 11.

[0035] The fixed section is a structural section that is fixedly assembled with the earphone shell. The fixed section has a through-hole for connection, and the fixed section is fastened to the earphone shell through the hole by a connector. The free section is a structural section without assembly constraints and can be freely deformed. That is to say, in the actual assembly state, the flexible circuit board 10 of this embodiment forms a cantilever structure with one end fixed and the other end free. The vibration of the piezoelectric element 20 is transmitted to the intermediate section 12 and the second functional section 13 through the first functional section 11. In the cantilever structure, the piezoelectric element 20 acts as a vibration excitation source, and its vibration energy is transmitted from the fixed end to the free end. The vibration energy is more concentrated closer to the excitation source. In this embodiment, the counterweight 30 is arranged on the side of the groove 121 near the first functional section 11, so that the counterweight 30 acts directly on the area where the vibration energy is concentrated as an additional mass load, changing the local modal frequency near the fixed section so that the excitation frequency is offset from the natural frequency. Thus, the source suppression can be achieved before the vibration energy is transmitted and amplified by the structure, thereby simplifying the vibration suppression structure and saving assembly space.

[0036] In some specific embodiments of this application, the first functional segment 11 is formed as a free segment, the second functional segment 13 is formed as a fixed segment, and the groove portion 121 is located on the side of the counterweight portion 30 close to the first functional segment 11.

[0037] Specifically, in the actual assembly state, the flexible circuit board 10 forms a cantilever structure with one end free and the other end fixed. The vibration of the piezoelectric element 20 is still transmitted to the intermediate section 12 and the second functional section 13 through the first functional section 11. Since the piezoelectric element 20 is arranged in the first functional section 11, the vibration energy is more concentrated closer to the excitation source during the transmission of vibration from the free section to the fixed section. In this embodiment, the counterweight 30 is arranged on the side of the groove 121 near the first functional section 11, so that the counterweight 30 acts directly on the area where the vibration energy is concentrated as an additional mass load. This changes the local modal frequency near the fixed end so that the excitation frequency is offset from the natural frequency. Thus, the source suppression can be achieved before the vibration energy is amplified by the structure, thereby simplifying the vibration suppression structure and saving assembly space.

[0038] According to one embodiment of this application, both the first functional segment 11 and the second functional segment 13 are formed as fixed segments, and the counterweight 30 is located on the side of the groove 121 close to the first functional segment 11.

[0039] In other words, the flexible circuit board 10 forms a double-fixed structure with both ends fixed in the actual assembly state. The first functional segment 11 and the second functional segment 13 are fixedly connected to different assembly points of the earphone shell, and the middle segment 12 is the bridging area between the fixed constraints at both ends. The piezoelectric element 20 is located in the first functional segment 11, and its vibration is transmitted to the middle segment 12 through the first functional segment 11 and further propagates to the second functional segment 13. In the double-fixed structure, the fixed constraints at both ends restrict the boundary displacement, and the middle segment 12 becomes the bridging area where the vibration energy is most concentrated and the structure is most prone to resonance. When the vibration wave generated by the piezoelectric element 20 propagates in the middle segment 12, it forms a standing wave due to boundary reflection, which significantly amplifies the amplitude at a specific position in the middle segment 12.

[0040] In this embodiment, the counterweight 30 is arranged on the side of the groove 121 near the first functional section 11, so that the counterweight 30 is located on the upstream path of the vibration energy transmission from the excitation source to the intermediate section 12. As an additional mass load, it directly acts on the area where the vibration energy is concentrated, changing the local modal frequency of the transition area between the first functional section 11 and the intermediate section 12 so that the excitation frequency is offset from the natural frequency. Thus, source suppression can be achieved before the vibration energy forms a standing wave amplification in the intermediate section 12, reducing the resonance response of the intermediate section 12 and reducing the operating noise.

[0041] In some specific embodiments of this application, the intermediate section 12 is provided with a plurality of grooves 121 spaced apart along the length direction, and the grooves 121 are elongated slots extending along the width direction of the flexible circuit board 10.

[0042] Specifically, multiple grooves 121 are arranged sequentially at intervals along the length of the flexible circuit board 10, and each groove 121 extends along the width of the flexible circuit board 10, with its extension direction perpendicular to the main vibration propagation direction, thereby maximizing the lateral blocking effect on the vibration propagation path. It should be noted that the number of grooves 121 can be flexibly selected according to the geometric dimensions of the vibration control area and the target modal frequency offset, so as to achieve the optimal balance between vibration suppression effect and structural integrity.

[0043] In this embodiment, the width of a single groove 121 does not need to be too large, which helps to ensure the structural strength of the flexible circuit board 10, and multiple grooves 121 help to adjust the vibration mode of the flexible circuit board 10 to the target range.

[0044] According to one embodiment of this application, the piezoelectric element 20 is a surface-mount capacitor.

[0045] In related technologies, surface-mount capacitors (such as audio SOC capacitors) are typically mounted on the flexible circuit board 10 of in-ear headphone products. Under the influence of audio electrical signals, these surface-mount capacitors undergo minute deformation due to the piezoelectric effect, resulting in periodic mechanical vibrations. These vibrations are transmitted to the flexible circuit board 10 via solder pads, causing coupled vibrations in a specific frequency band and resonance near its natural mode frequency. Specifically, this manifests as significant vibration amplification in the 4kHz–8kHz frequency band, a marked increase in electronic noise, and deterioration of acoustic performance (risk of abnormal noise and feedback).

[0046] In this embodiment, the synergistic effect of the counterweight 30 and the groove 121 can reduce the structural resonance generated by the patch capacitor excitation of the flexible circuit board 10, which can meet the product space constraints of the thin and light design of in-ear headphones. While preserving the bending performance and assembly space of the flexible circuit board 10, it can effectively suppress the resonance amplification in the 4kHz to 8kHz frequency band, reduce the risk of abnormal noise and howling, and improve the acoustic performance and product process consistency.

[0047] In some embodiments of this application, the counterweight 30 is a counterweight block or a counterweight coating.

[0048] Specifically, the counterweight can be made of high-density materials such as Cu, Ni, or stainless steel, providing a significant increase in mass within a small volume, thus meeting the tight assembly space requirements of headphones. The counterweight can be fixed to a preset position on the flexible circuit board 10 by welding or assembled using a surface mount technology (SMT). The assembly process is mature and can meet the standardization and high efficiency requirements of mass production. The counterweight coating can be achieved through a coating process, eliminating the need for additional mechanical assembly steps. Moreover, during product changeovers, only coating parameters (such as coating thickness, coating area, or coating material ratio) need to be adjusted, which can significantly shorten the product changeover cycle and reduce the manufacturing cost of molds or special tooling.

[0049] In some optional examples of this application, the groove 121 is a through groove or a blind groove.

[0050] When the groove 121 is a through groove, the structural stiffness of the flexible circuit board 10 at the groove 121 is reduced to the minimum value under through-hole conditions, and the stiffness adjustment range is large. This is suitable for situations where the local stiffness of the flexible circuit board 10 needs to be significantly reduced to shift the modal frequency. When the groove 121 is a blind groove, the flexible circuit board 10 retains uncut substrate material at the groove 121. Compared with a through groove, a blind groove can maintain the interlayer structural continuity of the flexible circuit board 10 while reducing local stiffness, thereby maintaining the overall structural strength of the flexible circuit board 10. In addition, the circuit traces of the flexible circuit board 10 can be set on the side without a blind groove, so that the circuit traces are isolated from the groove 121 in the layer thickness direction, which can meet the requirements of complex circuit trace layout.

[0051] In some specific embodiments of this application, the flexible circuit board 10 includes a first copper layer 101, a flexible base layer 102, and a second copper layer 103 stacked together; the groove portion 121 is formed as a blind groove penetrating the first copper layer 101 or the second copper layer 103, or the groove portion 121 is formed as a blind groove penetrating the first copper layer 101 or the second copper layer 103 and extending into the flexible base layer 102.

[0052] Specifically, the flexible circuit board 10 is composed of a first copper layer 101, a flexible base layer 102, and a second copper layer 103 stacked together. The first copper layer 101 and the second copper layer 103 are located on both sides of the flexible base layer 102 and form circuit traces. When the groove portion 121 is formed as a blind groove penetrating the first copper layer 101 or the second copper layer 103, only the copper layer material on the corresponding side needs to be removed, which makes it easy to precisely control the groove depth and width through the etching process and has good production compatibility. When the groove portion 121 is formed as a blind groove penetrating the copper layer and extending into the flexible base layer 102, the flexible circuit board 10 can be further thinned, the rigidity weakening is more significant, and the flexible base layer 102 retained at the bottom of the groove can prevent damage to the copper layer and its traces on the other side.

[0053] Embodiments of this application also provide a method for determining parameters of a flexible circuit assembly. This method is applied to the flexible circuit assembly described in any of the above embodiments, and the method includes: S1. Obtain the initial vibration mode parameters of the flexible circuit board 10 equipped with piezoelectric element 20; Specifically, modal simulation or an LDV laser Doppler vibrator is used to collect the initial vibration modal parameters of the original flexible circuit board 10, clarifying the resonance defects of the original structure in the predetermined frequency band, and providing a basis for parameter optimization. The vibration modal parameters include vibration amplitude, resonant frequency, and mode shape distribution.

[0054] S2. A counterweight 30 and a groove 121 are provided in the middle section 12 and / or the second functional section 13 of the flexible circuit board 10; In detail, based on the location of the initial modal defects, a counterweight structure and a slotted structure of the initial specifications are arranged in the vibration concentration area to build a preliminary optimized structure.

[0055] S3. Obtain the current vibration mode parameters of the flexible circuit board 10 again; Specifically, the same measurement method as in step S1 is used to test the optimized circuit board under the same working conditions and collect the vibration modal parameters of the current structure.

[0056] S4. Compare the current vibration modal parameters with the preset modal parameters; In detail, the preset modal parameters are vibration modal parameters that, compared to the initial vibration modal parameters, can effectively mitigate structural resonance and reduce acoustic noise of the flexible circuit board 10. These parameters can be adjusted according to design requirements. By comparing and determining whether the current vibration modal parameters match the preset modal parameters, if the current vibration modal parameters do not match the preset modal parameters, proceed to step S5.

[0057] S5. Adjust the design parameters of the groove 121 and the counterweight 30 according to the comparison results; Specifically, at least one of the opening position, size, and quantity of the groove portion 121 can be adjusted, and / or at least one of the installation position, counterweight mass, and coverage range of the counterweight portion 30 can be adjusted, in order to specifically correct the deviation between the current vibration mode and the preset modal parameters.

[0058] S6. Iteratively execute the step of obtaining the current vibration mode parameters of the flexible circuit board 10 until the current vibration mode parameters of the flexible circuit board 10 match the preset mode parameters. In detail, each iteration updates the current structural model with the design parameters adjusted in step S5, and repeats the modal parameter acquisition in step S3 and the comparison and judgment in step S4 to form a closed-loop optimization of "detection-comparison-correction" until the current vibration modal parameters match the preset modal parameters, and then the iteration terminates.

[0059] S7. The design parameters of the groove portion 121 and the counterweight portion 30 corresponding to the matching preset modal parameters are taken as the target design parameters.

[0060] Specifically, the target design parameters include the opening position, groove depth, groove width, number and arrangement spacing of the groove portion 121, as well as the installation position, counterweight mass and coverage of the counterweight portion 30. These target design parameters serve as the final shaping parameters of the vibration suppression structure of the flexible circuit board 10 and are used to prepare the flexible circuit assembly described in any of the above embodiments.

[0061] Therefore, according to the parameter determination method of the flexible circuit assembly of this application, the design parameters of the groove 121 and the counterweight 30 are determined by iterative optimization. The synergistic effect of the counterweight 30 and the groove 121 can effectively suppress the structural resonance generated by the piezoelectric element 20 exciting the flexible circuit board 10, so that the vibration mode of the flexible circuit board 10 reaches the preset requirements and the acoustic noise is reduced.

[0062] This application further illustrates the technical solutions of the embodiments of this application through the following examples and comparative examples.

[0063] Example 1 The flexible circuit assembly is prepared using the target design parameters determined by the above parameter determination method, and the first functional segment 11 and the second functional segment 13 are formed as fixed segments.

[0064] Under 8kHz testing conditions, the flexible circuit board 10 of this embodiment exhibits a first-order mode with a resonant frequency of 9.2kHz, a vibration displacement of 45nm, and a noise level of 17dBA.

[0065] Comparative Example 1 The only difference from Embodiment 1 is that the flexible circuit board 10 has a configuration portion and a recess portion 121.

[0066] Under the 8kHz test condition, the flexible circuit board 10 of this comparative example exhibits a first-order mode with a resonant frequency of 6.5kHz, a vibration displacement of 120nm, and a noise of 22dBA.

[0067] As can be seen from the comparison between Example 1 and Comparative Example 1, compared with Comparative Example 1 which does not have a counterweight 30 and a groove 121, the flexible circuit assembly of Example 1 of this application has a significant vibration reduction and noise reduction effect, wherein the vibration amplitude is reduced by about 62%, the noise is reduced by about 5 dBA, and the resonance peak is significantly weakened.

[0068] This application also provides an earphone, including the flexible circuit assembly described in any of the above embodiments. Since the flexible circuit assembly and its parameter determination method according to the embodiments of this application have the above-described technical effects, the earphone according to the embodiments of this application also has corresponding technical effects, which will not be repeated in this embodiment.

[0069] While specific embodiments of this application have been described in detail by way of examples, those skilled in the art should understand that the above examples are for illustrative purposes only and are not intended to limit the scope of this application. Those skilled in the art should understand that modifications can be made to the above embodiments without departing from the scope and spirit of this application. The scope of this application is defined by the appended claims.

Claims

1. A flexible circuit assembly, characterized in that, include: A flexible circuit board (10) includes a first functional segment (11), an intermediate segment (12) and a second functional segment (13) distributed along its length. A piezoelectric element (20) is disposed in the first functional segment (11); The counterweight (30) and the groove (121) are respectively or jointly arranged in at least one segment of the intermediate section (12) and the second functional section (13); The counterweight (30) is used to cooperate with the groove (121) to reduce the structural resonance generated by the piezoelectric element (20) exciting the flexible circuit board (10).

2. The flexible circuit assembly according to claim 1, characterized in that, The counterweight (30) and the groove (121) are both located in the middle section (12).

3. The flexible circuit assembly according to claim 1, characterized in that, The first functional segment (11) is formed as a fixed segment, the second functional segment (13) is formed as a free segment, and the counterweight (30) is located on the side of the groove (121) close to the first functional segment (11).

4. The flexible circuit assembly according to claim 1, characterized in that, The first functional segment (11) is formed as a free segment, the second functional segment (13) is formed as a fixed segment, and the groove (121) is located on the side of the counterweight (30) close to the first functional segment (11).

5. The flexible circuit assembly according to claim 2, characterized in that, Both the first functional segment (11) and the second functional segment (13) are formed as fixed segments, and the groove (121) is located on the side of the counterweight (30) close to the first functional segment (11).

6. The flexible circuit assembly according to claim 1, characterized in that, The middle section (12) is provided with a plurality of grooves (121) spaced apart along the length direction, and the grooves (121) are elongated grooves extending along the width direction of the flexible circuit board (10).

7. The flexible circuit assembly according to claim 1, characterized in that, The piezoelectric element (20) is a chip capacitor; and / or, the counterweight (30) is a counterweight block or a counterweight coating; and / or, the groove (121) is a through groove or a blind groove.

8. The flexible circuit assembly according to claim 1, characterized in that, The flexible circuit board (10) includes a first copper layer (101), a flexible base layer (102), and a second copper layer (103) stacked together. The groove portion (121) is formed as a blind groove penetrating the first copper layer (101) or the second copper layer (103), or the groove portion (121) is formed as a blind groove penetrating the first copper layer (101) or the second copper layer (103) and extending into the flexible base layer (102).

9. A method for determining the parameters of a flexible circuit component, characterized in that, Applied to the flexible circuit assembly as described in any one of claims 1-8, the parameter determination method includes: Obtain the initial vibration mode parameters of the flexible circuit board (10) equipped with piezoelectric element (20); A counterweight (30) and a recess (121) are provided in the middle section (12) and / or the second functional section (13) of the flexible circuit board (10). Obtain the current vibration mode parameters of the flexible circuit board (10); The current vibration modal parameters are compared with the preset modal parameters; Adjust the design parameters of the groove (121) and the counterweight (30) according to the comparison results; The step of obtaining the current vibration mode parameters of the flexible circuit board (10) is executed iteratively until the current vibration mode parameters of the flexible circuit board (10) match the preset mode parameters. The design parameters of the groove (121) and the counterweight (30) corresponding to the matching of the preset modal parameters are taken as the target design parameters.

10. An earphone, characterized in that, Includes the flexible circuit assembly as described in any one of claims 1-8.

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