A soldering method for earphone audio terminals and earphone

Abstract

This disclosure relates to a welding method for headphone audio terminals and a headphone. The welding method for headphone audio terminals includes fixing the audio terminals; irradiating the vacant terminal positions with a calibration laser at a level lower than the melting threshold of the vacant terminal positions and collecting the thermal radiation signal of the vacant terminal positions; extracting thermal response feature values ​​from the thermal radiation signals, correcting preset welding parameters based on the thermal response feature values ​​to obtain welding laser parameters for each terminal position to be welded; placing the exposed conductors of each single wire in their corresponding terminal positions to be welded; and applying welding laser to the connection area between each exposed conductor and the corresponding terminal position to be welded according to the welding laser parameters to form a laser welded joint. This technical solution can utilize the vacant terminal positions to reflect the heating state of the same audio terminal, thereby adjusting the laser heat input to the terminal positions to be welded, reducing the influence of differences in terminal surface condition, plating condition, and heat dissipation on welding quality, and improving welding consistency and conductivity reliability.

Description

Technical Field

[0001] This disclosure relates to the field of laser welding technology for connecting headphone audio terminals to wire harnesses, and more specifically, to a welding method for headphone audio terminals and a headphone. Background Technology

[0002] Headphones typically require electrical connection to an external audio interface via audio terminals. One side of the audio terminal is for plugging into the external interface, while the other side has terminals for connecting the cable. The 4-pin cable used internally in headphones generally refers to a cable harness structure with four independent conductive wires, each used to transmit different audio signals, control signals, or ground signals. (See attached image) Figure 1 As shown, in order to ensure that the headphones function properly, each wire needs to be connected to the corresponding terminal of the audio terminal according to the predetermined correspondence, so that the audio terminal can form a stable electrical connection with the internal circuit of the headphones.

[0003] In current assembly processes, the insulation of each individual wire of the 4-pin cable is typically stripped to expose the internal conductors. These exposed conductors are then placed or inserted into the corresponding terminals of the audio terminals, and soldered to connect them. With the miniaturization of headphone products, the soldering area of ​​the audio terminals is smaller, and the spacing between adjacent terminals is also smaller, requiring concentrated heat input to complete the connection during soldering. However, the surface condition, plating condition, and local heat dissipation conditions of audio terminals can vary between different batches. When using fixed soldering parameters, insufficient heat input at some terminals can lead to incomplete connections, while excessive heat input at others can cause overheating of the soldering area. This results in poor consistency of the solder joints across different terminals, affecting the conductivity stability and reliability of the headphone audio terminals after connection to the wiring harness.

[0004] It should be noted that the information disclosed in the background section above is only used to enhance the understanding of the background of this disclosure. Summary of the Invention

[0005] The purpose of this disclosure is to provide a welding method for headphone audio terminals and a headphone, in order to solve the technical problem that existing headphone audio terminal welding methods with multi-core wire harnesses have fixed welding parameters that are difficult to adapt to the surface condition and local heat dissipation differences of audio terminals, resulting in poor weld joint consistency.

[0006] Other features and advantages of this disclosure will become apparent from the following detailed description, or may be learned in part from practice of this disclosure.

[0007] According to one aspect of this disclosure, a soldering method for an audio terminal of an earphone is provided. The audio terminal has a plurality of terminal positions, including at least one unused terminal position and a plurality of terminal positions to be soldered. Each terminal position to be soldered is used to connect a single wire of a multi-core wire harness. The soldering method includes: Fix the audio terminal; The vacant terminal is irradiated with a calibration laser at a level lower than the melting threshold of the vacant terminal, and the thermal radiation signal of the vacant terminal is collected. Thermal response feature values ​​are extracted from the thermal radiation signal, and preset welding parameters are corrected based on the thermal response feature values ​​to obtain the welding laser parameters for each of the terminals to be welded. Place the exposed conductors of each of the single wires in their respective terminals to be soldered. According to the welding laser parameters, a welding laser is applied to the connection area between each of the exposed conductors and the corresponding terminal to be welded, forming a laser welded joint.

[0008] According to one aspect of this disclosure, an earphone is provided, the earphone including an audio terminal and a multi-core wire harness, the audio terminal having a plurality of terminal positions, the plurality of terminal positions including at least one unused terminal position and a plurality of terminal positions to be soldered, the multi-core wire harness including a plurality of single wires respectively connected to each of the terminal positions to be soldered, and a laser welding joint being formed between the exposed conductor of each single wire and the corresponding terminal position to be soldered, the laser welding joint being formed using the welding method for the earphone audio terminal of the above embodiment.

[0009] As can be seen from the above technical solutions, the soldering method for the audio terminal of the earphone and the earphone in the exemplary embodiments of this disclosure have at least the following advantages and positive effects: In some embodiments of this disclosure, when connecting the headphone audio terminal to a multi-core wire harness, the audio terminal is first fixed to maintain its positional stability during subsequent calibration and soldering. Since the audio terminal simultaneously has unused terminal positions and multiple terminal positions to be soldered, the unused terminal positions, although not involved in the wire harness connection, are part of the same audio terminal and typically have similar material conditions, surface conditions, and heat dissipation environments to the terminal positions to be soldered. Therefore, before formally soldering each terminal position, irradiating the unused terminal positions with a calibration laser below the melting threshold of the unused terminal positions will not cause melting or structural damage to the unused terminal positions, while simultaneously allowing the unused terminal positions to undergo thermal changes under the actual surface conditions and heat dissipation conditions of the current audio terminal. Collecting the thermal radiation signal during this heating process and extracting thermal response characteristic values ​​from the thermal radiation signal can reflect the absorption of laser energy and heat dissipation of the audio terminal under the current processing state.

[0010] After obtaining the thermal response characteristic values, the preset welding parameters are corrected to obtain the welding laser parameters for each terminal to be welded, making the welding process applicable to intelligent welding systems with adaptive parameter adjustment capabilities. Thus, the laser parameters used during actual welding no longer rely solely on fixed empirical values ​​but are correlated with the actual heating performance of the same audio terminal. Subsequently, the exposed conductors of each individual wire in the multi-core harness are placed at their corresponding terminal positions, and welding lasers are applied to the connection areas between each exposed conductor and its corresponding terminal position according to the corrected welding laser parameters. Since the welding laser parameters have been adjusted based on the thermal response of the unused terminal positions, insufficient heat in the connection area can be avoided when the audio terminal surface has strong reflection, slow heating, or rapid heat dissipation; conversely, excessive heat input can be avoided when the audio terminal heats up rapidly or has significant heat retention. Therefore, each terminal position can obtain a heat input closer to the actual requirements during welding, forming a stable laser welding joint between the exposed conductor and the terminal position, and improving the conductivity stability and welding consistency after the audio terminal is connected to the multi-core harness.

[0011] It should be understood that the foregoing general description and the following detailed description are exemplary and explanatory only, and are not intended to limit this disclosure. Attached Figure Description

[0012] The accompanying drawings, which are incorporated in and form part of this specification, illustrate embodiments consistent with this disclosure and, together with the description, serve to explain the principles of this disclosure. It is obvious that the drawings described below are merely some embodiments of this disclosure, and those skilled in the art can obtain other drawings based on these drawings without any inventive effort. In the drawings: Figure 1 This is a schematic diagram of the structure after the audio terminal is connected to the 4-pin cable; Figure 2 This diagram illustrates the changes in thermal radiation and reflected light intensity signals during the calibration of an unused terminal. Figure 3 This is a schematic diagram of an embodiment of the welding method for headphone audio terminals according to the present invention.

[0013] Explanation of icon numbers: 1. Audio terminal; 11. Unused terminal; 12. Terminal to be soldered; 2. Single wire. Detailed Implementation

[0014] The technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative effort are within the scope of protection of the present invention.

[0015] It should be noted that if the embodiments of the present invention involve directional indicators (such as up, down, left, right, front, back, etc.), the directional indicators are only used to explain the relative positional relationship and movement of the components in a specific posture. If the specific posture changes, the directional indicators will also change accordingly.

[0016] Furthermore, the use of terms such as "first" and "second" in this invention is for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of those features. Additionally, the term "and / or" throughout the text includes three solutions; taking A and / or B as an example, it includes technical solution A, technical solution B, and a technical solution that simultaneously satisfies A and B. Furthermore, the technical solutions of various embodiments can be combined with each other, provided that they are feasible for those skilled in the art. When the combination of technical solutions is contradictory or impossible to implement, it should be considered that such a combination of technical solutions does not exist and is not within the scope of protection claimed by this invention.

[0017] This disclosure discloses a soldering method for headphone audio terminals.

[0018] In this embodiment of the invention, the audio terminal has multiple terminal positions, including at least one unused terminal position and multiple terminal positions to be soldered. Each terminal position to be soldered is used to connect a single wire of a multi-core wire harness. Please refer to [link to relevant documentation]. Figure 3 Welding methods include: Fix the audio terminal; The vacant terminal is irradiated with a calibration laser at a level lower than the melting threshold of the vacant terminal, and the thermal radiation signal of the vacant terminal is collected. Thermal response feature values ​​are extracted from the thermal radiation signal, and preset welding parameters are corrected based on the thermal response feature values ​​to obtain the welding laser parameters for each of the terminals to be welded. Place the exposed conductors of each of the single wires in their respective terminals to be soldered. According to the welding laser parameters, a welding laser is applied to the connection area between each of the exposed conductors and the corresponding terminal to be welded, forming a laser welded joint.

[0019] Specifically, in this embodiment, after the audio terminal is fixed, a terminal position on the audio terminal that is not connected to a single wire of the multi-core wire harness is selected as an unused terminal position, and this unused terminal position is irradiated with a calibration laser. Although the unused terminal position does not participate in the final electrical connection, it still belongs to the metal terminal structure of the same audio terminal and can reflect the thermal changes under the current batch material, current surface condition, current clamping state, and current heat dissipation conditions along with the audio terminal. The energy of the calibration laser is lower than the melting threshold of the unused terminal position, so that the unused terminal position only produces detectable temperature rise and cooling changes, without melting, collapse, plating damage, or surface morphology changes. The melting threshold can be determined according to the terminal material, surface treatment layer, laser wavelength, spot size, and irradiation time, or it can be determined by pre-testing similar terminal samples.

[0020] When calibrating an unused terminal block with a laser, the thermal radiation signal of the unused terminal block changing over time can be collected using an infrared detector, a thermal radiation sensor, or a coaxial temperature measurement component. From this thermal radiation signal, at least one of the following can be extracted as thermal response characteristic values: heating slope, peak thermal radiation value, heating time required to reach a preset thermal radiation intensity, and cooling decay characteristics after irradiation stops. The heating slope and heating time reflect the rate at which the unused terminal block heats up under the calibration laser, the peak thermal radiation value reflects the degree of heating reached, and the cooling decay characteristics reflect the rate at which heat dissipates to the surrounding structure after irradiation stops. Through these collectable and comparable characteristic values, the difference in heating of the current audio terminal block under calibration laser conditions relative to a reference state can be determined.

[0021] Preset welding parameters can include basic parameters corresponding to each terminal to be welded. These basic parameters can be predetermined based on the structural dimensions, material, surface treatment layer, and connection method to the exposed conductor of each terminal. For example, when the terminals to be welded have different surface treatment layers or different welding areas, each terminal can correspond to different basic pulse energy, basic pulse number, basic laser peak power, or basic scanning dwell time. In this way, the differences between the terminals to be welded due to differences in structure or surface treatment layer are reflected by their respective basic parameters, rather than being directly replaced by the thermal response of unused terminals.

[0022] After obtaining the thermal response characteristic value of the vacant terminal, this value is compared with the reference thermal response range. Based on the comparison result, the basic parameters corresponding to each terminal to be welded are corrected to obtain the welding laser parameters. The reference thermal response range can be obtained by collecting thermal radiation signals from the vacant terminal of a qualified sample under the same calibrated laser conditions, or by performing trial welding on samples that meet the welding strength and conductivity requirements. When the heating slope of the vacant terminal is lower than the reference range, the peak thermal radiation value is lower than the reference range, the heating time is higher than the reference range, or the cooling attenuation characteristic is higher than the reference range, it indicates that the effective heat input obtained by the current audio terminal under the same laser conditions is too low. In this case, the basic parameters of each terminal to be welded are incrementally corrected, for example, by increasing the pulse energy, increasing the number of pulses, or extending the scanning dwell time. When the heating slope of the unused terminal is higher than the reference range, the peak heat radiation is higher than the reference range, the heating time is lower than the reference range, or the cooling attenuation characteristic is lower than the reference range, it indicates that the current audio terminal is easier to heat up or has a longer heat retention time. In this case, the basic parameters of each terminal to be soldered should be reduced, such as reducing pulse energy, reducing the number of pulses, or shortening the scanning dwell time.

[0023] In one embodiment, the vacant terminal and each terminal to be soldered have the same or similar surface treatment layer. In this case, the thermal response characteristic value of the vacant terminal can directly reflect the photothermal response state of the terminal to be soldered, and the correction of the preset welding parameters can be applied to the basic parameters of each terminal to be soldered according to the same correction rule. In another embodiment, the vacant terminal and at least one terminal to be soldered have different surface treatment layers. In this case, the basic parameters of each terminal to be soldered are predetermined according to its own surface treatment layer. The thermal response characteristic value of the vacant terminal is used to determine the overall heating deviation of the current audio terminal relative to the reference state, and incremental or subtractive corrections are made based on the basic parameters of each terminal to be soldered. Thus, even if the surface treatment layers of the vacant terminal and the terminal to be soldered are different, the welding laser parameters can be determined by the basic parameters of the terminal to be soldered and the thermal response correction of the vacant terminal, without simply considering their thermal responses to be exactly the same.

[0024] After the welding laser parameters are determined, the exposed conductors of each individual wire in the multi-core wire harness are placed at their corresponding welding terminals. A welding laser is then applied to the connection area between the exposed conductor and the welding terminal, forming a laser-welded joint. The welding terminal can be a pad, solder hole, solder foot, or other metal connection area capable of forming a laser-welded joint with the exposed conductor. Because the welding laser parameters are obtained by modifying the basic parameters of each welding terminal by incorporating the thermal response characteristics of unused terminals, the welding process can simultaneously consider the structural differences of the welding terminals and the actual heating state of the audio terminals, thereby reducing thermal input deviations caused by fixed welding parameters.

[0025] In some embodiments of this disclosure, based on the foregoing scheme, the plurality of terminal positions include a first terminal position, a second terminal position, a third terminal position, a fourth terminal position, and a fifth terminal position arranged sequentially in the same direction, wherein the third terminal position is the unused terminal position, and the first terminal position, the second terminal position, the fourth terminal position, and the fifth terminal position are the terminal positions to be soldered, and the multi-core wire harness is a 4-pin wire.

[0026] Specifically, in the above embodiments, the same direction can be the arrangement direction of multiple terminal positions on the audio terminal. The first to fifth terminal positions are used to indicate the relative order of each terminal position in this arrangement direction, without limiting the absolute direction of the audio terminal in the use state. The terminal position can be a pad, solder hole, solder foot, or other metal connection area that can form a solder joint with the wire harness conductor.

[0027] In this embodiment, the multi-core wire harness is a 4-pin wire, which includes four insulated individual wires. The insulation layer of each individual wire is stripped to expose the conductor. The first, second, fourth, and fifth terminals are designated as soldering terminals, used to connect to the exposed conductors of the four individual wires in the 4-pin wire. The third terminal is not connected to any of the individual wires in the 4-pin wire and is considered an unused terminal. Therefore, although the third terminal does not participate in the electrical connection of the wire harness, it still belongs to the terminal structure of the audio terminal itself and can be used for calibrating laser irradiation and thermal radiation signal acquisition before the formal soldering of the first, second, fourth, and fifth terminals.

[0028] In some embodiments of this disclosure, based on the foregoing scheme, the vacant terminal positions and each of the terminal positions to be soldered have the same surface treatment layer.

[0029] It should be noted that the surface treatment layer can be a tin plating layer, nickel plating layer, gold plating layer, nickel-gold plating layer, or other surface layer formed on the surface of the terminal metal substrate to improve the conductivity, oxidation resistance, or solderability of the terminal. The same surface treatment layer can be understood as the treatment layer on the surface of the vacant terminal and each terminal to be soldered having the same material system and layered structure, allowing for thickness differences within manufacturing tolerances. Because the vacant terminal and each terminal to be soldered have the same surface treatment layer, under the action of the calibration laser, the absorption, reflection, and thermal radiation of laser energy by the vacant terminal and the terminal to be soldered are more similar. Therefore, the thermal response characteristic value of the vacant terminal can be used more directly as a reference for correcting the soldering laser parameters of each terminal to be soldered, allowing the soldering laser parameters to be more accurately adapted to the actual surface condition and heat dissipation condition of the same audio terminal.

[0030] In some embodiments of this disclosure, based on the foregoing scheme, the process of extracting thermal response feature values ​​from the thermal radiation signal includes: Based on the thermal radiation signal, at least one of the following is obtained as the thermal response characteristic value: the heating slope of the vacant terminal, the peak value of thermal radiation, the heating time required to reach the preset thermal radiation intensity, and the cooling attenuation characteristic after the irradiation stops.

[0031] In this embodiment, the thermal radiation signal can be a signal showing the change in thermal radiation intensity of the vacant terminal during and after calibration laser irradiation. When the calibration laser begins irradiation, the vacant terminal absorbs laser energy and heats up, causing the thermal radiation signal to rise. After the calibration laser stops irradiation, the heat from the vacant terminal is transferred to other metal structures of the audio terminal, welding fixtures, or the surrounding environment, causing the thermal radiation signal to decrease. Therefore, by processing the changes in the thermal radiation signal during the heating, peak, and cooling phases, thermal response characteristic values ​​characterizing the heated state of the vacant terminal can be obtained.

[0032] Specifically, the heating slope can be determined by the ratio of the rise in thermal radiation signal within a preset time period after the calibration laser begins irradiation to that preset time period, indicating how quickly the vacant terminal block heats up under the calibration laser. The thermal radiation peak value can be the maximum value reached by the thermal radiation signal during or around the end of the calibration laser irradiation, indicating the degree of heating achieved by the vacant terminal block during this calibration process. The heating time required to reach the preset thermal radiation intensity can be the time elapsed from the start of the calibration laser irradiation until the thermal radiation signal reaches the preset thermal radiation intensity, indicating how quickly the vacant terminal block reaches the target heating state. The preset thermal radiation intensity can be determined based on the thermal radiation data of a qualified sample under calibration laser irradiation, or it can be determined based on the safe heating range that will not cause melting or changes in the surface morphology of the vacant terminal block.

[0033] The cooling attenuation characteristics after irradiation stops can be determined based on the decrease in thermal radiation signal after the calibration laser stops irradiation. For example, the cooling attenuation characteristics can be the decrease in thermal radiation signal within a preset time period after irradiation stops, the time required for the thermal radiation signal to decrease from its peak value to a preset percentage, or the slope of the thermal radiation signal decrease during the cooling phase. The cooling attenuation characteristics reflect the rate of heat dissipation from unoccupied terminals after calibration. Faster cooling attenuation indicates that heat from unoccupied terminals is more easily transferred to the surrounding structure; slower cooling attenuation indicates that heat from unoccupied terminals is retained for a relatively longer period.

[0034] The aforementioned heating slope, peak thermal radiation, heating time, and cooling attenuation characteristics can be used individually as thermal response characteristic values, or two or more of them can be used together as thermal response characteristic values. Using at least one thermal response characteristic value allows for the acquisition of the current audio terminal's response to the calibration laser from the actual heating changes of the vacant terminal position; using multiple thermal response characteristic values ​​simultaneously reflects the heating rate, degree of heating, and heat dissipation rate, making subsequent corrections to the preset welding parameters more stable.

[0035] In some embodiments of this disclosure, the process of correcting the preset welding parameters based on the aforementioned scheme and the thermal response characteristic values ​​includes: The thermal response characteristic value is compared with the corresponding preset thermal response range; When the heating slope is less than the lower limit of the corresponding preset heating slope range, the peak thermal radiation is less than the lower limit of the corresponding preset peak range, the heating time is greater than the upper limit of the corresponding preset heating time range, or the cooling attenuation characteristic is greater than the upper limit of the corresponding preset cooling attenuation range, the pulse energy, pulse number, or scanning dwell time in the preset welding parameters are increased. When the heating slope is greater than the upper limit of the corresponding preset heating slope range, the peak thermal radiation is greater than the upper limit of the corresponding preset peak range, the heating time is less than the lower limit of the corresponding preset heating time range, or the cooling attenuation characteristic is less than the lower limit of the corresponding preset cooling attenuation range, the pulse energy, pulse number, or scanning dwell time in the preset welding parameters are reduced.

[0036] It should be noted that, in this embodiment, the preset thermal response range can be determined based on calibration data of similar audio terminals under qualified welding conditions. For example, several audio terminal samples that have been confirmed to form stable laser welded joints can be selected, and their empty terminal positions can be irradiated under the same calibration laser conditions, and the corresponding thermal radiation signals can be collected. Subsequently, the heating slope, thermal radiation peak value, heating time, and cooling attenuation characteristics are extracted from the thermal radiation signals, and the corresponding preset heating slope range, preset peak value range, preset heating time range, and preset cooling attenuation range are determined based on the characteristic value distribution of these samples. Therefore, the preset thermal response range is not an arbitrarily set fixed value, but corresponds to the heating state of the terminal that can obtain a qualified welded joint.

[0037] Before actual welding, the thermal response characteristic value of the unused terminal of the current audio terminal under calibration laser irradiation is compared with the corresponding preset thermal response range. When the heating slope is less than the lower limit of the preset heating slope range, it indicates that the thermal radiation signal of the unused terminal rises slowly per unit time; when the thermal radiation peak value is less than the lower limit of the preset peak value range, it indicates that the degree of heating reached by the unused terminal during calibration is low; when the heating time is greater than the upper limit of the preset heating time range, it indicates that the time required for the unused terminal to reach the preset thermal radiation intensity is long; when the cooling attenuation characteristic is greater than the upper limit of the preset cooling attenuation range, it indicates that the thermal radiation signal drops rapidly after irradiation stops, and the heat of the unused terminal is more easily dissipated to the surrounding structure. Any of the above situations indicates that the current audio terminal is not likely to obtain sufficient heat or has weak heat retention capacity under the same laser conditions. If the original preset welding parameters are continued, the connection area between the terminal to be welded and the exposed conductor may have insufficient fusion. Therefore, the pulse energy, pulse number, or scanning dwell time in the preset welding parameters can be increased to provide more effective heat input to the connection area by the welding laser.

[0038] Correspondingly, when the heating slope is greater than the upper limit of the preset heating slope range, it indicates that the vacant terminal is heated up relatively quickly; when the peak heat radiation value is greater than the upper limit of the preset peak value range, it indicates that the vacant terminal has reached a relatively high degree of heating; when the heating time is less than the lower limit of the preset heating time range, it indicates that the vacant terminal reaches the preset heat radiation intensity relatively quickly; when the cooling attenuation characteristic is less than the lower limit of the preset cooling attenuation range, it indicates that the heat radiation signal decreases slowly after irradiation stops, and the heat retention time of the vacant terminal is relatively long. Any of the above situations indicates that the current audio terminal is more likely to heat up or accumulate heat under the same laser conditions. If the original preset welding parameters are continued, the connection area may be overheated, the welding area may expand, or the surface condition of the terminal may be damaged. Therefore, the pulse energy, pulse number, or scanning dwell time in the preset welding parameters can be reduced to match the heat input during the welding process with the actual heating state of the current audio terminal.

[0039] In this context, pulse energy can be understood as the energy input to the connection area by a single laser pulse; the number of pulses can be understood as the number of laser pulses acting on the same connection area during a single welding process; and the scanning dwell time can be understood as the time the welding laser remains in effect within the connection area. Increasing the pulse energy, pulse number, or scanning dwell time can increase the total heat input received by the connection area; decreasing the pulse energy, pulse number, or scanning dwell time can reduce the total heat input borne by the connection area. In practice, only one parameter can be adjusted, or two or more parameters can be adjusted simultaneously. For example, when the thermal response characteristic value deviates only slightly from the preset thermal response range, the scanning dwell time can be adjusted first; when the thermal response characteristic value deviates significantly from the preset thermal response range, the pulse energy and pulse number can be adjusted simultaneously to make the welding laser parameters more quickly approach the processing state suitable for the current audio terminal.

[0040] When using multiple thermal response characteristic values ​​for joint judgment, parameter correction can be made based on any thermal response characteristic value exceeding its corresponding preset range, or the correction magnitude can be determined by comprehensively considering the deviation directions of multiple thermal response characteristic values. When the correction directions corresponding to different thermal response characteristic values ​​are consistent, the preset welding parameters can be increased or decreased in that consistent direction; when the correction directions corresponding to different thermal response characteristic values ​​are inconsistent, the thermal response characteristic value with higher correlation to the actual weld joint quality can be prioritized for correction, or a smaller correction can be used and the final welding laser parameters can be determined through trial welding data. In this way, there is a clear correspondence between thermal response characteristic values ​​and preset welding parameters, which can avoid the problem that fixed welding parameters cannot adapt to the actual heating differences of different audio terminals.

[0041] In some embodiments of this disclosure, based on the foregoing scheme, during the process of irradiating the vacant terminal with a calibration laser, the reflected light intensity signal of the vacant terminal is also collected, and a photothermal calibration coefficient is determined based on the reflected light intensity signal and the thermal radiation signal, and the preset welding parameters are corrected based on the photothermal calibration coefficient.

[0042] In this embodiment, the reflected light intensity signal can be acquired by a photodetector coaxially arranged with the laser processing head, or by a light intensity collector located in the direction of the calibration laser reflection. This reflected light intensity signal is used to represent the degree of reflection of the calibration laser by the surface of the vacant terminal. To reduce the influence of the calibration laser's own output fluctuations on the judgment result, the reflected light intensity signal can be a normalized signal, for example, by comparing the light intensity reflected back from the vacant terminal with the real-time output light intensity of the calibration laser to obtain the reflection intensity characterization value.

[0043] The thermal radiation signal indicates the temperature change of the vacant terminal during and after calibration laser irradiation, while the reflected light intensity signal indicates the degree to which the calibration laser is reflected back from the vacant terminal. These two signals have different meanings. Judging solely from the thermal radiation signal, a slow temperature rise or low peak thermal radiation at the vacant terminal only indicates insufficient heating, but it's difficult to determine whether the insufficient heating stems from strong surface reflection or rapid heat dissipation from the terminal structure. By simultaneously acquiring the reflected light intensity signal, the effective absorption of the calibration laser by the vacant terminal can be further identified, thus providing a clearer direction for subsequent welding parameter adjustments.

[0044] The photothermal calibration coefficient can be determined jointly based on the reflected light intensity signal and the thermal radiation signal. Specifically, the reference reflected light intensity range and the reference thermal response range can be determined first using qualified samples. The reference reflected light intensity range can be determined by the distribution of reflected light intensity signals at the vacant terminals of the qualified sample under the same calibration laser conditions. The reference thermal response range can be determined by the heating slope, thermal radiation peak, heating time, or cooling attenuation characteristics of the vacant terminals of the qualified sample under the same calibration laser conditions. During actual processing, the reflected light intensity signal of the current vacant terminal is compared with the reference reflected light intensity range, and the thermal response characteristic value of the current vacant terminal is compared with the reference thermal response range. The photothermal calibration coefficient is determined based on the deviation between the two.

[0045] In one specific implementation, when the reflected light intensity signal is higher than the reference reflected light intensity range, and the thermal radiation signal shows that the heating slope of the vacant terminal is low, the thermal radiation peak is low, or the heating time is long, it can be determined that the reflection of the calibration laser by the current vacant terminal is too strong, and the actual absorbed laser energy is too low. At this time, the photothermal calibration coefficient can be determined as a coefficient to increase the laser energy input, and the laser peak power or pulse energy in the preset welding parameters can be increased accordingly. When the reflected light intensity signal is within or below the reference reflected light intensity range, but the thermal radiation signal still shows that the heating is slow or the cooling is fast, it can be determined that the insufficient heating is more likely related to the rapid heat dissipation of the terminal and the insufficient heat retention time in the connection area. At this time, the photothermal calibration coefficient can be determined as a coefficient to extend the thermal action time, and the number of pulses can be increased or the scanning dwell time can be extended accordingly.

[0046] In another specific implementation, when the reflected light intensity signal is lower than the reference reflected light intensity range, and the thermal radiation signal shows that the heating slope of the vacant terminal is too high, the thermal radiation peak is too high, or the heating time is too short, it can be determined that the current vacant terminal absorbs the calibration laser strongly, and the connection area is at risk of overheating during the actual welding. At this time, the photothermal calibration coefficient can be determined as a coefficient to reduce the laser heat input, and accordingly the pulse energy, pulse number, or scanning dwell time in the preset welding parameters are reduced. Therefore, the photothermal calibration coefficient is not used to directly detect the thickness or composition of the surface treatment layer, but rather to represent the correspondence between the reflection state and the heating state of the current vacant terminal under the action of the calibration laser.

[0047] When correcting preset welding parameters based on photothermal calibration coefficients, adjustments can be made based on the fundamental parameters of each terminal to be welded. For example, each terminal can have pre-defined fundamental pulse energy, fundamental pulse count, fundamental laser peak power, or fundamental scan dwell time; the photothermal calibration coefficients are used to determine the correction direction and magnitude of these fundamental parameters. When the photothermal calibration coefficients indicate insufficient effective absorption, the laser peak power or pulse energy is increased first; when the photothermal calibration coefficients indicate insufficient heat retention, the pulse count or scan dwell time is increased first; when the photothermal calibration coefficients indicate strong absorption or significant heat accumulation, the corresponding thermal input parameters are decreased. In this way, both reflected light intensity signals and thermal radiation signals participate in the welding parameter correction, reducing the problem of unclear determination of the cause of insufficient heating when relying solely on thermal radiation signals.

[0048] In some embodiments of this disclosure, the process of correcting the preset welding parameters based on the aforementioned scheme and the photothermal calibration coefficient includes: When the reflected light intensity signal is greater than the reference reflection intensity and the thermal response characteristic value is lower than the reference thermal response range, the laser peak power in the preset welding parameters is increased. When the reflected light intensity signal is not greater than the reference reflection intensity and the thermal response characteristic value is lower than the reference thermal response range, the number of pulses or the scanning dwell time in the preset welding parameters are increased.

[0049] In this embodiment, the reference reflection intensity can be determined based on the reflected light intensity signal collected from the unused terminal of the qualified sample under the same calibration laser conditions, or it can be determined based on the reflection ratio after normalization of the real-time output light intensity of the calibration laser. The reference thermal response range can be determined based on the thermal response characteristic value formed by the unused terminal of the qualified sample under the same calibration laser conditions. A thermal response characteristic value lower than the reference thermal response range can be understood as insufficient heating of the unused terminal, for example, a temperature rise slope lower than the reference range, a thermal radiation peak lower than the reference range, or a time required to reach the preset thermal radiation intensity longer than the reference range.

[0050] When the reflected light intensity signal is greater than the reference reflection intensity, and the thermal response characteristic value is lower than the reference thermal response range, it indicates that a significant amount of energy is reflected by the surface after the calibration laser is applied to the unused terminal, resulting in insufficient laser energy actually absorbed by the unused terminal. In this case, simply extending the scanning dwell time or increasing the number of pulses may increase the total input energy, but it easily expands the heat-affected zone. Increasing the laser peak power can increase the instantaneous energy density per unit pulse, allowing the irradiated area to receive a stronger effective energy input, thus better compensating for insufficient absorption caused by excessive surface reflection. Therefore, in this situation, the laser peak power in the preset welding parameters can be increased.

[0051] When the reflected light intensity signal is not greater than the reference reflection intensity, and the thermal response characteristic value is lower than the reference thermal response range, it indicates that the surface reflection of the unused terminal is not significantly higher. Insufficient heating is more likely related to the large heat capacity of the terminal itself, rapid heat dissipation between the terminal and the surrounding metal structure or fixture, and insufficient heat retention time. In this case, directly increasing the laser peak power will cause localized instantaneous excessive temperature, while the overall heat accumulation in the connection area will still be insufficient. Therefore, the number of pulses or the scanning dwell time in the preset welding parameters can be increased to allow the welding laser to form more sufficient heat accumulation in the connection area, thereby compensating for the low heating caused by rapid heat dissipation or insufficient heat retention.

[0052] In some embodiments of this disclosure, based on the foregoing scheme, the exposed conductor is composed of multiple filaments. Before placing the exposed conductors of each single wire at the corresponding terminal to be soldered, the exposed conductors are bundled to ensure that the width of the loose filament envelope of the exposed conductor is not greater than the effective soldering width of the corresponding terminal to be soldered.

[0053] In this embodiment, the exposed conductor of a single wire in a multi-core harness can be composed of multiple fine filaments, such as multiple copper wires, tinned copper wires, or other conductive filaments twisted together. After the insulation layer is stripped from the end of the single wire, the multiple fine filaments lose the constraint of the insulation layer and are prone to loosening, turning outward, or locally lifting at the end or middle. If the exposed conductor is placed directly on the terminal to be soldered in this state, some fine filaments may deviate from the laser welding area of ​​the terminal to be soldered, causing the welding laser to only act on some fine filaments, or causing the outward-turned fine filaments to approach adjacent terminals, affecting the connection stability and the safe insulation distance between terminals after welding.

[0054] The filament envelope width can be understood as the maximum lateral width of the multiple filaments in the exposed conductor projected onto the surface of the terminal block to be welded. Specifically, before the exposed conductor is placed onto the terminal block, the maximum distance between the outermost filaments can be measured along a direction perpendicular to the single-wire entry direction, and this maximum distance can be used as the filament envelope width. The effective weld width can be understood as the width range on the corresponding terminal block that allows the exposed conductor to participate in laser welding. This width range can be determined by the width of the metal connection area of ​​the terminal block, the width of the welding laser spot, the safe distance between the terminals, and the area where a weld joint is allowed to form. The effective weld width is not necessarily the same as the overall width of the terminal block, but rather refers to the width of the welding area that allows the exposed conductor to reliably connect to the terminal block without easily affecting adjacent terminals.

[0055] Before placing the exposed conductors of each individual wire onto their respective terminals, a bundled treatment is performed on the exposed conductors to ensure that the multiple filaments maintain a relatively concentrated shape when entering the terminal. This bundled treatment can employ mechanical clamping, guiding and gathering, pressing and shaping, or other methods that reduce the lateral spread of the multiple filaments. After the bundled treatment, the envelope width of the exposed conductor's filaments is no greater than the effective welding width of the corresponding terminal, allowing the multiple filaments to be uniformly within the laser welding range of the terminal. This allows the welding laser to be applied more concentratedly to the connection area between the exposed conductor and the terminal, reducing the likelihood of some filaments not participating in the welding, filaments overlapping adjacent terminals, or uncontrolled weld joint width.

[0056] In some embodiments of this disclosure, the process of converging the exposed conductor based on the foregoing scheme includes: The exposed conductor is passed through a convergence channel that gradually narrows along the direction of entry to gather together the multiple filaments; After the exposed conductor passes through the convergence channel, the end of the exposed conductor away from the insulation layer is subjected to a bundle end forming process, so that multiple filaments form a bundle end forming part at the end of the exposed conductor, and the length of the bundle end forming part is less than the exposed length of the exposed conductor.

[0057] Specifically, the incoming direction can be understood as the direction in which the end of a single wire is fed into the convergence channel. The convergence channel gradually narrows along this direction, meaning the entrance width of the convergence channel is greater than the exit width. After the exposed conductor enters the convergence channel, multiple filaments first enter a relatively wide entrance area. Then, as the exposed conductor continues to advance, they are guided and constrained by the sidewalls of the channel, causing the originally loose, outward-curving, or laterally spread filaments to gradually converge towards the center. The width at the exit of the convergence channel can be determined based on the effective welding width of the corresponding terminal to be soldered, ensuring that after the exposed conductor leaves the convergence channel, the envelope width of the multiple filaments is limited to within the effective welding width of the terminal to be soldered.

[0058] After the exposed conductor passes through the convergence channel, end-forming treatment can be performed on the end of the exposed conductor furthest from the insulation layer. This furthest end refers to the free end of the exposed conductor, which is the outermost end region after the insulation layer has been removed and is most prone to loosening or warping. End-forming treatment can employ methods such as pressing, rolling, clamping and shaping, micro-thermal pressing, or low-energy spot fixing to form a relatively stable end-forming portion at the end of the exposed conductor from multiple filaments. This end-forming portion helps maintain the convergence of the multiple filament ends, reducing the likelihood of secondary scattering of the exposed conductor during transfer, placement at the welding terminal, and before exposure to the welding laser.

[0059] The length of the bundled end forming section is less than the exposed length of the exposed conductor. This means that only a portion of the exposed conductor near its free end is shaped, rather than the entire exposed portion being compacted or fixed. This design allows the exposed conductor end to remain closed by the bundled end forming section, while the section near the insulation layer retains some flexibility, facilitating the contact or placement of the exposed conductor into the connection area of ​​the terminal to be soldered. If the bundled end forming section is too long, the exposed conductor may become too rigid overall or its local thickness may increase, which would hinder sufficient contact with the terminal to be soldered. If no bundled end forming section is formed at all, the free end of the filaments can easily unravel again. Therefore, making the length of the bundled end forming section less than the exposed length of the exposed conductor achieves a balance between preventing the ends from unraveling and ensuring the exposed conductor can be soldered and fitted.

[0060] According to one aspect of this disclosure, an earphone is provided, the earphone including an audio terminal and a multi-core wire harness, the audio terminal having a plurality of terminal positions, the plurality of terminal positions including at least one unused terminal position and a plurality of terminal positions to be soldered, the multi-core wire harness including a plurality of single wires respectively connected to each of the terminal positions to be soldered, and a laser welding joint being formed between the exposed conductor of each single wire and the corresponding terminal position to be soldered, the laser welding joint being formed using the welding method for the earphone audio terminal of the above embodiment.

[0061] like Figure 1As shown, in a specific product structure, the multi-core wire harness can be a 4-pin wire. The 4-pin wire includes multiple single wires 2 that are insulated from each other. After the insulation layer is stripped from the end of each single wire 2, an exposed conductor is formed, and it is connected to the corresponding terminal on the wire harness connection side of the audio terminal 1. Figure 1 The audio terminal 1 has a plug for mating with an external audio interface and a wire harness connection side for connecting 4-pin wires. Each single wire 2 is arranged along the wire harness connection side of the audio terminal 1 and forms a connection with the corresponding terminal position 12 to be soldered. For an exposed conductor composed of multiple filaments, before it is placed to the corresponding terminal position 12 to be soldered, the multiple filaments are first gathered together by a gathering channel and a bundle end forming process. This allows the exposed conductor to enter the effective soldering area of ​​the terminal position 12 to be soldered in a more concentrated form, reducing the possibility of filaments turning outward, lifting, or deviating from the terminal position 12 to be soldered. This facilitates the subsequent concentrated action of the soldering laser on the connection area between the exposed conductor and the terminal position 12 to be soldered.

[0062] In the above product structure, the terminal not connected to the single wire 2 in the 4-pin line can be used as an unused terminal 11. Although this unused terminal 11 does not participate in the electrical connection of the wire harness, it still belongs to the metal terminal structure of the same audio terminal 1, and therefore can be used as the irradiation position for calibration laser before the formal soldering of each terminal 12 to be soldered.

[0063] like Figure 2 As shown, the horizontal axis t represents time, and the vertical axis I represents the normalized signal intensity. S1 represents the thermal radiation signal of the idle terminal during and after calibration laser irradiation; S2 represents the reflected light intensity signal of the idle terminal during calibration laser irradiation; T1 represents the moment when calibration laser irradiation begins; T2 represents the moment when calibration laser irradiation stops; R1 represents the preset thermal radiation intensity; and R2 represents the reference reflected intensity. A represents the temperature rise slope obtained based on the thermal radiation signal S1 during the heating phase; B represents the peak thermal radiation value reached by the thermal radiation signal S1; C represents the heating time required for the thermal radiation signal S1 to reach the preset thermal radiation intensity R1; and D represents the cooling attenuation characteristics of the thermal radiation signal S1 after calibration laser irradiation stops. Figure 2 The signal curve in the figure is used to illustrate the relative trend of the signal change over time during the calibration process. The vertical axis I can be represented by the normalized signal intensity, and is not limited to a specific temperature value, absolute value of radiation intensity or absolute value of reflected light intensity.

[0064] Other embodiments of this disclosure will readily occur to those skilled in the art upon consideration of the specification and practice of the invention disclosed herein. This application is intended to cover any variations, uses, or adaptations of this disclosure that follow the general principles of this disclosure and include common knowledge or customary techniques in the art not disclosed herein. The specification and examples are to be considered exemplary only, and the true scope and spirit of this disclosure are indicated by the following claims.

[0065] It should be understood that this disclosure is not limited to the precise structures described above and shown in the accompanying drawings, and various modifications and changes can be made without departing from its scope. The scope of this disclosure is limited only by the appended claims.

Claims

1. A soldering method for headphone audio terminals, characterized in that, The audio terminal has multiple terminal positions, including at least one unused terminal position and multiple terminal positions to be soldered. Each terminal position to be soldered is used to connect a single wire of a multi-core wire harness. The soldering method includes: Fix the audio terminal; The vacant terminal is irradiated with a calibration laser at a level lower than the melting threshold of the vacant terminal, and the thermal radiation signal of the vacant terminal is collected. Thermal response feature values ​​are extracted from the thermal radiation signal, and preset welding parameters are corrected based on the thermal response feature values ​​to obtain the welding laser parameters for each of the terminals to be welded. Place the exposed conductors of each of the single wires in their respective terminals to be soldered. According to the welding laser parameters, a welding laser is applied to the connection area between each of the exposed conductors and the corresponding terminal to be welded, forming a laser welded joint.

2. The soldering method for headphone audio terminals according to claim 1, characterized in that, The plurality of terminal positions include a first terminal position, a second terminal position, a third terminal position, a fourth terminal position, and a fifth terminal position arranged sequentially in the same direction. The third terminal position is the unused terminal position. The first terminal position, the second terminal position, the fourth terminal position, and the fifth terminal position are the terminals to be soldered. The multi-core wire harness is a 4-pin wire.

3. The soldering method for headphone audio terminals according to claim 1, characterized in that, The unused terminal blocks and each of the terminal blocks to be soldered have the same surface treatment layer.

4. The soldering method for headphone audio terminals according to claim 1, characterized in that, The process of extracting thermal response feature values ​​from the thermal radiation signal includes: Based on the thermal radiation signal, at least one of the following is obtained as the thermal response characteristic value: the heating slope of the vacant terminal, the peak value of thermal radiation, the heating time required to reach the preset thermal radiation intensity, and the cooling attenuation characteristic after the irradiation stops.

5. The soldering method for headphone audio terminals according to claim 4, characterized in that, The process of correcting the preset welding parameters based on the thermal response characteristic values ​​includes: The thermal response characteristic value is compared with the corresponding preset thermal response range; When the heating slope is less than the lower limit of the corresponding preset heating slope range, the peak thermal radiation is less than the lower limit of the corresponding preset peak range, the heating time is greater than the upper limit of the corresponding preset heating time range, or the cooling attenuation characteristic is greater than the upper limit of the corresponding preset cooling attenuation range, the pulse energy, pulse number, or scanning dwell time in the preset welding parameters are increased. When the heating slope is greater than the upper limit of the corresponding preset heating slope range, the peak thermal radiation is greater than the upper limit of the corresponding preset peak range, the heating time is less than the lower limit of the corresponding preset heating time range, or the cooling attenuation characteristic is less than the lower limit of the corresponding preset cooling attenuation range, the pulse energy, pulse number, or scanning dwell time in the preset welding parameters are reduced.

6. The soldering method for headphone audio terminals according to claim 1, characterized in that, During the process of irradiating the vacant terminal with a calibration laser, the reflected light intensity signal of the vacant terminal is also collected, and the photothermal calibration coefficient is determined based on the reflected light intensity signal and the thermal radiation signal. The preset welding parameters are then corrected based on the photothermal calibration coefficient.

7. The soldering method for headphone audio terminals according to claim 6, characterized in that, The process of correcting the preset welding parameters based on the photothermal calibration coefficient includes: When the reflected light intensity signal is greater than the reference reflection intensity and the thermal response characteristic value is lower than the reference thermal response range, the laser peak power in the preset welding parameters is increased. When the reflected light intensity signal is not greater than the reference reflection intensity and the thermal response characteristic value is lower than the reference thermal response range, the number of pulses or the scanning dwell time in the preset welding parameters are increased.

8. The soldering method for headphone audio terminals according to claim 1, characterized in that, The exposed conductor is composed of multiple fine wires. Before placing each of the single wires of the exposed conductor into the corresponding terminal position to be soldered, the exposed conductor is bundled to ensure that the width of the loose wire envelope of the exposed conductor is not greater than the effective welding width of the corresponding terminal position to be soldered.

9. The soldering method for headphone audio terminals according to claim 8, characterized in that, The process of converging the exposed conductor includes: The exposed conductor is passed through a convergence channel that gradually narrows along the direction of entry to gather together the multiple filaments; After the exposed conductor passes through the convergence channel, the end of the exposed conductor away from the insulation layer is subjected to a bundle end forming process, so that multiple filaments form a bundle end forming part at the end of the exposed conductor, and the length of the bundle end forming part is less than the exposed length of the exposed conductor.

10. An earphone, characterized in that, The device includes an audio terminal and a multi-core wire harness. The audio terminal has multiple terminal positions, including at least one unused terminal position and multiple terminal positions to be soldered. The multi-core wire harness includes multiple single wires that are respectively connected to each of the terminal positions to be soldered. A laser welding joint is formed between the exposed conductor of each single wire and the corresponding terminal position to be soldered. The laser welding joint is formed using the welding method for headphone audio terminals as described in any one of claims 1 to 9.

Images